CN110658703A

CN110658703A - Method of attaching regulating blade and developing apparatus

Info

Publication number: CN110658703A
Application number: CN201910570724.2A
Authority: CN
Inventors: 津留崎辉明; 古贺俊一; 潮见友洋
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 2018-06-29
Filing date: 2019-06-28
Publication date: 2020-01-07
Anticipated expiration: 2039-06-28
Also published as: JP2020008839A; KR102353590B1; PH12019000225A1; JP7254615B2; CN110658703B; KR20200002674A

Abstract

The present disclosure relates to a method of attaching a regulating blade made of resin to an attachment portion of a developing frame made of resin and including an attachment portion for attaching the regulating blade, the method including: applying an adhesive to the attachment portion; applying a hardening accelerator to a management blade; and attaching the regulating blade to the attachment portion via the adhesive applied to the attachment portion and the hardening accelerator applied to the regulating blade. The regulating blade is disposed opposite to and not in contact with a developing rotary member configured to carry and convey a developer toward a position where an electrostatic latent image formed on an image bearing member is developed, and is configured to regulate an amount of the developer carried on the developing rotary member. The present disclosure also relates to a developing apparatus.

Description

Method of attaching regulating blade and developing apparatus

Technical Field

The present disclosure relates to a method of incorporating a regulating blade made of resin.

Background

The developing device includes a developing frame, a developer carrying member, and a regulating blade. The developer carrying member carries a developer for developing an electrostatic latent image formed on the image bearing member. The regulating blade is a developer regulating member that regulates an amount of developer (coating amount) carried on the developer carrying member. The regulating blade is disposed opposite to the developer carrying member in a longer side direction of the developer carrying member with a predetermined gap, that is, a sleeve-blade gap (hereinafter referred to as "SB gap") between the regulating blade and the developer carrying member (developing sleeve). The SB gap means the shortest distance between the developer carrying member and the regulating blade. The amount of developer conveyed toward the position where the electrostatic latent image formed on the image bearing member is developed (the developing region where the developer bearing member faces the image bearing member) is adjusted by adjusting the size of the SB gap.

In recent years, there has been known a developing apparatus including a developer regulating member molded of a resin and made of a resin and a developing frame molded of a resin and made of a resin (see japanese patent application laid-open No. 2014-197175).

As the width of the sheet on which the image is to be formed increases, the length of the maximum image area (in which the image can be formed on the image bearing member) in the longer-side direction thereof increases, so that the length of the surface of the regulating blade in the longer-side direction (coating amount regulating surface) that regulates the amount of the developer carried on the developer bearing member increases. Therefore, as the width of the sheet on which an image is to be formed increases, the length of the region of the regulating blade in the longer-side direction corresponding to the maximum image area of the image bearing member (hereinafter referred to as "the maximum image area of the regulating blade") increases. In the case of a resin molding regulating blade (long in the longer side direction), the thermal shrinkage rate of the resin after thermal expansion generally varies in the longer side direction of the regulating blade. Therefore, in the case where the resin molding is performed with the usual accuracy of the resin molded article with the regulating blade long in the longer side direction, it is difficult to ensure the flatness of the coating amount regulating surface of the resin molding regulating blade.

Therefore, in the case of the regulating blade made of resin, the longer the coating amount regulating surface is in the longer side direction, the more likely the SB gap is to vary significantly in the longer side direction of the developer carrying member due to the flatness of the coating amount regulating surface. If the SB gap varies in the longer side direction of the developer carrying member, the coating amount of the developer may vary in the longer side direction of the developer carrying member. Therefore, in the developing device including the regulating blade made of resin, regardless of the flatness of the coating amount regulating surface, the SB gap needs to be in a predetermined range along the longer side direction of the developer carrying member, and a force for warping the regulating blade needs to be exerted on the regulating blade.

Therefore, the resin regulating blade is warped such that the SB gap is within a predetermined range in the longer side direction of the developer carrying member, and the regulating blade in the warped state is fixed to a portion of the developing frame to which the regulating blade is to be fixed (hereinafter referred to as "blade attachment portion"). At this time, in order to prevent the regulating blade from returning to the original state from the warped state, it is desirable to fix the regulating blade in the warped state over the entire area of the blade attachment portion corresponding to the maximum image area of the image bearing member (hereinafter referred to as "the maximum image area of the blade attachment portion"). This is because, if the regulating blade in the warped state is fixed to the blade attachment portion and then returns from the warped state to the original state, the SB gap varies in the longer side direction of the developer carrying member regardless of whether the SB gap is adjusted to be within a predetermined range in the longer side direction of the developer carrying member.

Therefore, in the developing device including the regulating blade made of resin and the developing frame made of resin, it is desirable to fix the regulating blade in a warped state over the entire maximum image area of the blade attachment portion. A possible method for fixing the regulating blade in a warped state over the entire maximum image area of the blade attachment portion is to use an adhesive. For example, an adhesive having a predetermined layer thickness is applied to a surface of the blade attachment portion (blade attachment surface) to which the regulating blade is to be attached. In order to fix the regulating blade in a warped state over the entire maximum image area of the blade attachment portion using the adhesive, the adhesive needs to be applied over the entire maximum image area of the blade attachment surface.

With the usual precision of the adhesive application apparatus, the layer thickness of the adhesive applied to the blade attachment surface by the adhesive application apparatus configured to apply the adhesive to the blade attachment surface by moving the adhesive application unit in the longer-side direction varies in the longer-side direction of the blade attachment surface.

As described above, as the width of the sheet on which the image is to be formed increases, the length of the regulating blade in the longer-side direction of the maximum image area increases, so that the length of the blade attachment surface (to which the regulating blade extending in the longer-side direction is to be attached) in the longer-side direction of the maximum image area also increases. Further, the longer the length of the blade attachment surface in the direction of the longer side of the maximum image area, the more likely the layer thickness of the adhesive applied to the blade attachment surface by the adhesive application device will vary significantly in the direction of the longer side of the blade attachment surface.

The length of time required for the adhesive to harden to obtain sufficient bonding strength of the regulating blade with respect to the blade attachment surface (hereinafter simply referred to as "adhesive hardening time") is proportional to the layer thickness of the adhesive. Specifically, the thicker the layer thickness of the adhesive, the longer the adhesive hardening time becomes, and the thinner the layer thickness of the adhesive, the shorter the adhesive hardening time becomes. Thus, if the layer thickness of the adhesive applied to the blade attachment surface varies in the longer side direction of the blade attachment surface, the hardening time of the adhesive applied to the blade attachment surface also varies in the longer side direction of the blade attachment surface. Especially in the case where the adhesive application apparatus applies adhesive to the entire maximum image area to which the regulating blade extending in the longer-side direction is to be attached, the degree of variation in the adhesive hardening time is more likely to be significant in the longer-side direction of the blade attachment surface.

If the adhesive hardening time varies significantly in the longer-side direction of the blade attachment surface, when a predetermined time elapses after the adhesive is applied, the adhesive is sufficiently hardened at some portions and not at some other portions in the longer-side direction of the blade attachment surface. In the case where the adhesive is sufficiently hardened at some portions and not sufficiently hardened at some other portions in the longer-side direction of the blade attachment surface, the length of time spent in the bonding step in the developing device manufacturing process needs to be set according to the portions at which the adhesive is not sufficiently hardened. Specifically, when a predetermined time elapses after the adhesive is applied, even if the adhesive is sufficiently hardened at a certain portion in the longer side direction of the blade attachment surface, as long as there is another portion at which the adhesive is not sufficiently hardened, it is necessary to wait until the adhesive at the portion at which the adhesive is not sufficiently hardened is sufficiently hardened. Therefore, a possible variation in the layer thickness of the adhesive to be applied to the blade attachment surface by the adhesive applying apparatus is estimated in advance, and the length of time spent in bonding in the process of manufacturing the developing apparatus is set.

From the viewpoint of mass production, it is desirable that the time taken in the bonding step in the developing device manufacturing process is short, and it is also desirable that the adhesive hardening time in the bonding step is short. This is because if the adhesive hardening time is reduced, the tact time can be shortened, which is advantageous from the viewpoint of mass production. As described above, the adhesive hardening time is determined based on the layer thickness of the applied adhesive (specifically, the amount of the applied adhesive). Therefore, the amount of adhesive to be applied to the blade attachment surface by the adhesive applying apparatus during the bonding step is set as described below. Specifically, in order to prevent the regulating blade from being deformed by the application of the reagent pressure to the regulating blade generated by the flow of the developer during the image forming operation, the bonding force of the regulating blade with respect to the blade attachment surface needs to be sufficiently higher than the reagent pressure. Therefore, the force that regulates the peeling of the blade from the blade attachment surface due to the reagent pressure and the bonding force of the adhesive using a common adhesive material are considered, and the amount of the adhesive to be applied to the blade attachment surface by the adhesive applying apparatus is set to an appropriate amount.

Then, in the case of using a common adhesive material as the adhesive and setting the amount of the adhesive to be applied to the blade attachment surface to an appropriate amount, consideration is given to how to prevent such a change in the adhesive hardening time caused by a change in the layer thickness of the adhesive applied to the blade attachment surface. Regarding the change in the adhesive hardening time, the longer the adhesive hardening time, the more significant the change in the adhesive hardening time becomes, and the shorter the adhesive hardening time, the less significant the change in the adhesive hardening time becomes. Therefore, in order to reduce the degree of variation in the hardening time of the adhesive, a hardening accelerator for accelerating the hardening of the adhesive may be applied to accelerate the hardening of the adhesive applied to fix the resin doctor blade extending in the longer-side direction thereof to the blade attachment portion.

Disclosure of Invention

The present disclosure relates to a technique for reducing the length of time required to bond a regulating blade made of resin to a developing frame made of resin.

According to an aspect of the present disclosure, the present disclosure relates to a method of attaching a regulating blade to an attachment portion of a developing frame, the regulating blade being made of resin, the developing frame being made of resin and including an attachment portion for attaching the regulating blade, the method including: a first application step of applying an adhesive to the attachment portion; a second application step of applying a hardening accelerator to the regulating blade; and an attaching step of attaching the regulating blade to the attaching portion via the adhesive applied to the attaching portion in the first applying step and the hardening accelerator applied to the regulating blade in the second applying step. The regulating blade is disposed opposite to and not in contact with a developing rotary member configured to carry and convey a developer toward a position where an electrostatic latent image formed on an image bearing member is developed, and is configured to regulate an amount of the developer carried on the developing rotary member.

According to another aspect of the present disclosure, the present disclosure relates to a method of attaching a regulating blade to an attachment portion of a developing frame, the regulating blade being made of resin, the developing frame being made of resin and including an attachment portion for attaching the regulating blade, the method including: a first application step of applying an adhesive to the regulating blade; a second application step of applying a hardening accelerator to the attachment portion; and an attaching step of attaching the regulating blade to the attaching portion via the adhesive applied to the regulating blade in the first applying step and the hardening accelerator applied to the attaching portion in the second applying step. The regulating blade is disposed opposite to and not in contact with a developing rotary member configured to carry and convey a developer toward a position where an electrostatic latent image formed on an image bearing member is developed, and is configured to regulate an amount of the developer carried on the developing rotary member.

According to still another aspect of the present disclosure, the present disclosure relates to a developing apparatus including: a developing rotary member configured to carry a developer and convey the developer toward a position where an electrostatic latent image formed on an image bearing member is developed; a regulating blade made of resin, disposed opposite to the developing rotary member, and not in contact with the developing rotary member; and a developing frame made of resin and including an attaching portion for attaching the regulating blade. The regulating blade is configured to regulate an amount of the developer carried on the developing rotary member. The regulating blade is bonded to the attachment portion by an adhesive and a hardening accelerator.

Other features of the present disclosure will become apparent from the following description of exemplary embodiments, which refers to the accompanying drawings.

Drawings

Fig. 1 is a sectional view showing the structure of an image forming apparatus.

Fig. 2 is a perspective view illustrating the structure of a developing apparatus according to the first exemplary embodiment.

Fig. 3 is a perspective view illustrating the structure of the developing device according to the first exemplary embodiment.

Fig. 4 is a sectional view showing the structure of the developing device according to the first exemplary embodiment.

Fig. 5 is a perspective view showing the structure of a doctor blade (single piece) made of resin.

Fig. 6 is a perspective view showing the structure of a developing frame (single article) made of resin.

Fig. 7 is a schematic view showing the rigidity of a doctor blade (single piece) made of resin.

Fig. 8 is a schematic view showing the rigidity of a developing frame (single article) made of resin.

Fig. 9 is a schematic view showing the flatness of a doctor blade (single article) made of resin.

Fig. 10 is a perspective view showing a deformation of the ink scraping blade made of resin caused by a temperature change.

Fig. 11 is a sectional view showing deformation of the ink scraping blade made of resin caused by the reagent pressure.

Fig. 12 shows the chemical formula of the adhesive.

Fig. 13 shows the chemical formula of the hardening accelerator.

Fig. 14 is a schematic view showing steps of a method of incorporating the ink scraping blade made of resin according to the first exemplary embodiment.

Fig. 15 is a schematic view showing steps of a method of incorporating the ink scraping blade made of resin according to the second exemplary embodiment.

Fig. 16 is a schematic view showing the orientation of the developing frame and the doctor blade during the application of the adhesive and the hardening accelerator.

Fig. 17 is a schematic view showing the orientation of the developing frame and the doctor blade during the joining of the developing frame and the doctor blade.

Detailed Description

Various exemplary embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. It should be noted that the exemplary embodiments described below are not intended to limit the scope of the claimed disclosure, and not every combination of features described in the first exemplary embodiment is always indispensable to the technical solution of the present disclosure. The present disclosure is applicable to various uses, such as printers, various printing machines, copying machines, facsimile machines, and multifunction peripherals.

(Structure of image Forming apparatus)

First, the structure of an image forming apparatus according to a first exemplary embodiment of the present disclosure will be described below with reference to a sectional view shown in fig. 1. As shown in fig. 1, the image forming apparatus 60 includes an endless Intermediate Transfer Belt (ITB)61 as an intermediate transfer member and four image forming units 600 disposed from an upstream side to a downstream side in a rotational direction of the ITB 61 (a direction of an arrow C in fig. 1). The four image forming units 600 form yellow (Y), magenta (M), cyan (C), and black (Bk) toner images, respectively.

Each of the image forming units 600 includes a photosensitive drum 1 as a rotatable image bearing member. Further, the image forming unit 600 includes a charging roller 2 as a charging unit, a developing device 3 as a developing unit, a primary transfer roller 4 as a primary transfer unit, and a photosensitive member cleaner 5 as a photosensitive member cleaning unit. The charging roller 2, the developing device 3, the primary transfer roller 4, and the photosensitive member cleaner 5 are disposed along the rotational direction of the photosensitive drum 1.

Each developing device 3 is removable from the image forming device 60 and attachable to the image forming device 60. Each developing device 3 includes a developing container 50, and the developing container 50 stores a two-component developer (hereinafter, simply referred to as "developer") containing a nonmagnetic toner (hereinafter, simply referred to as "toner") and a magnetic carrier. Further, the toner cartridges storing Y, M, C and Bk toner, respectively, are both removable from and attachable to the image forming apparatus 60. Y, M, C and Bk toner are supplied to the respective developing containers 50 through toner conveying paths. Details of the developing device 3 will be described below with reference to fig. 2 to 4, and details of the developing container 50 will be described below with reference to fig. 5.

The ITB 61 is stretched by the tension roller 6, the driven roller 7a, the primary transfer roller 4, the driven roller 7b, and the inner secondary transfer roller 66, and is driven and conveyed in the direction of arrow C in fig. 1. The inner secondary transfer roller 66 also serves as a drive roller that drives the ITB 61. When the inner secondary transfer roller 66 rotates, the ITB 61 rotates in the direction of arrow C in fig. 1.

The ITB 61 is pressed by the primary transfer roller 4 from the rear surface side of the ITB 61. Further, the ITB 61 is in contact with the photosensitive drum 1, thereby forming a primary transfer nip as a primary transfer portion between the photosensitive drum 1 and the ITB 61.

An intermediate transfer member cleaner 8 as a belt cleaning unit is in contact with the ITB 61 at a position opposed to the tension roller 6 via the ITB 61. Further, an outer secondary transfer roller 67 as a secondary transfer unit is provided at a position opposed to the inner secondary transfer roller 66 via the ITB 61. The ITB 61 is sandwiched between an inner secondary transfer roller 66 and an outer secondary transfer roller 67. In this way, a secondary transfer nip as a secondary transfer portion is formed between the outer secondary transfer roller 67 and the ITB 61. In the secondary transfer nip, a predetermined pressing force and a transfer bias (electrostatic load bias) are applied so that the toner image is adsorbed onto the surface of a sheet S (e.g., paper, film).

The sheets S are stored in a stacked state in a sheet storage unit 62 (e.g., a sheet feeding cassette, a sheet feeding deck). The sheet feeding unit 63 feeds the sheet S in synchronization with the image forming time using, for example, a friction separation method using a sheet feeding roller. The sheet S fed by the sheet feeding unit 63 is conveyed to registration rollers 65 provided at positions on the conveying path 64. After skew correction and time correction are performed on the sheet S at the registration rollers 65, the sheet S is conveyed to the secondary transfer nip. In the secondary transfer nip, the timing of the sheet S and the timing of the toner image are synchronized, and secondary transfer is performed.

The fixing device 9 is disposed downstream of the secondary transfer nip in the conveying direction of the sheet S. A predetermined pressure and a predetermined heat are applied from the fixing device 9 to the sheet S conveyed to the fixing device 9, so that the toner image is melted and fixed onto the surface of the sheet S. The sheet S having the image fixed as described above is directly discharged onto the sheet discharge tray 601 by forward rotation of the sheet discharge roller 69.

In the case of performing the duplex image formation, after the trailing edge of the sheet S passes through the switching member 602 by the forward rotation of the sheet discharging roller 69, the sheet discharging roller 69 rotates backward. In this way, the sheet S is conveyed to the double-sided conveyance path 603 with the leading edge and the trailing edge being interchanged. After that, the sheet S is conveyed again to the conveying path 64 by the sheet re-feeding roller 604 in temporal synchronization with the next image formation.

(image formation Process)

In image formation, the photosensitive drum 1 is driven and rotated by a motor. The charging roller 2 uniformly charges the surface of the photosensitive drum 1 driven and rotated in advance. The exposure device 68 forms an electrostatic latent image on the surface of the photosensitive drum 1 charged by the charging roller 2 based on a signal of image information input to the image forming device 60. The photosensitive drum 1 forms electrostatic latent images of various sizes.

The developing device 3 includes a developing sleeve 70 (developing rotary member) as a developer carrying member, the developing sleeve 70 being rotatable and carrying the developer. The developing device 3 develops the electrostatic latent image formed on the surface of the photosensitive drum 1 with the developer carried on the developing sleeve 70. In this way, the toner adheres to the exposed portion on the surface of the photosensitive drum 1, thereby visualizing the image. A transfer bias (electrostatic load bias) is applied to the primary transfer roller 4, and the toner image formed on the surface of the photosensitive drum 1 is transferred onto the ITB 61. The toner (untransferred toner) remaining on the surface of the photosensitive drum 1 by a small amount after the primary transfer is collected by the photosensitive member cleaner 5 to be ready for the next image forming process.

The processes of forming Y, M, C and Bk images are performed in parallel by the respective image forming units 600 at respective timings at which each image is sequentially superimposed on the upstream color toner image primarily transferred onto ITB 61. Thus, a full-color toner image is formed on the ITB 61, and the toner image is conveyed to the secondary transfer nip. A transfer bias is applied to the outer secondary transfer roller 67, and the toner image formed on the ITB 61 is transferred onto the sheet S conveyed to the secondary transfer nip. A toner (untransferred toner) remaining on the ITB 61 in a small amount after the sheet S passes through the secondary transfer nip is collected by the intermediate transfer member cleaner 8. The fixing device 9 fixes the transferred toner image to the sheet S. The sheet S to which the toner image is fixed by the fixing device 9 is discharged onto a sheet discharge tray 601.

The above-described series of image forming processes is ended, and the image forming apparatus 60 is ready for the next image forming operation.

(Structure of developing device)

Next, the structure of the developing device 3 according to the first exemplary embodiment of the present disclosure will be described below with reference to the perspective views in fig. 2 and 3 and the sectional view in fig. 4. Fig. 4 is a sectional view showing the developing device 3 along a cross section H designated in fig. 2.

The developing device 3 includes a developing container 50, and the developing container 50 includes a developing frame (hereinafter simply referred to as "developing frame 30") molded of resin and made of resin, and a cover frame (hereinafter simply referred to as "cover frame 40") formed separately from the developing frame 30 and molded of resin and made of resin. Fig. 2 and 4 show a state in which the cover frame 40 is attached to the developing frame 30, and fig. 3 shows a state in which the cover frame 40 is not attached to the developing frame 30. Details of the structure of the developing frame 30 (single article) will be described below with reference to fig. 6.

The developing container 50 includes an opening formed at a position corresponding to a developing region in which the developing sleeve 70 faces the photosensitive drum 1. The developing sleeve 70 is rotatably provided with respect to the developing container 50 so as to expose a part of the developing sleeve 70 from the opening of the developing container 50. Each end portion of the developing sleeve 70 is provided with a bearing 71, and the bearing 71 is a bearing member.

The interior of the developing container 50 is divided (partitioned) into a developing chamber 31 as a first chamber and an agitating chamber 32 as a second chamber by a partition wall 38 extending in the vertical direction. The developing chamber 31 and the stirring chamber 32 are connected to each other at respective ends in the longer-side direction by two communicating portions 39 of the partition wall 38. Therefore, the developer can be transferred between the developing chamber 31 and the stirring chamber 32 through the communication portion 39. The developing chamber 31 and the stirring chamber 32 are arranged adjacent to each other in the horizontal direction.

A magnetic roller as a magnetic field generating unit that includes a plurality of magnetic poles along the rotational direction of the developing sleeve 70 and generates a magnetic field for causing the developer to be carried on the surface of the developing sleeve 70 is provided and fixed in the developing sleeve 70. The developer in the developing chamber 31 is sucked out and supplied to the developing sleeve 70 due to the influence of the magnetic field generated by the magnetic poles of the magnetic roller. In this way, the developer is supplied from the developing chamber 31 to the developing sleeve 70, so that the developing chamber 31 is also referred to as a supply chamber.

In the developing chamber 31, the first conveyance screw 33 is disposed opposite to the developing sleeve 70. The first conveying screw 33 is a conveying unit, and the first conveying screw 33 agitates and conveys the developer in the developing chamber 31. The first conveyance screw 33 includes a rotation shaft 33a and a blade portion 33b, and is rotatably supported with respect to the developing container 50. The rotation shaft 33a is a rotatable shaft portion, and the blade portion 33b is a spiral developer conveying portion provided along the outer periphery of the rotation shaft 33 a. Each end portion of the rotating shaft 33a is provided with a bearing member.

Further, a second conveyance screw 34 as a conveyance unit is provided in the stirring chamber 32. The second conveyance screw 34 agitates the developer in the agitation chamber 32 and conveys the developer in the direction opposite to the first conveyance screw 33. The second conveyance screw 34 includes a rotary shaft 34a and a blade portion 34b, and is rotatably supported with respect to the developing container 50. The rotation shaft 34a is a rotatable shaft portion, and the blade portion 34b is a spiral developer conveying portion provided along the outer periphery of the rotation shaft 34 a. Each end portion of the rotating shaft 34a is provided with a bearing member. Further, the first conveying screw 33 and the second conveying screw 34 are driven and rotated, so that a circulation path through which the developer is circulated through the communication part 39 is formed between the developing chamber 31 and the agitating chamber 32.

A regulating blade (hereinafter referred to as "the ink scraping blade 36") as a developer regulating member is attached in the developing container 50 opposite to the surface of the developing sleeve 70, and is not in contact with the surface of the developing sleeve 70. The doctor blade 36 regulates an amount of developer (also referred to as "developer coating amount") carried on the surface of the developing sleeve 70. The doctor blade 36 includes a coating amount regulating surface 36r as a regulating portion, the coating amount regulating surface 36r regulating the amount of the developer carried on the surface of the developing sleeve 70. The doctor blade 36 is molded from resin and made of resin. The structure of the doctor blade 36 (single article) will be described below with reference to fig. 5.

The ink scraping blade 36 is disposed opposite the developing sleeve 70 in a longer side direction of the developing sleeve 70 (specifically, a direction parallel to the rotational axis of the developing sleeve 70) with a predetermined gap, i.e., a sleeve-blade gap G (hereinafter referred to as "SB gap G") between the ink scraping blade 36 and the developing sleeve 70. In the present exemplary embodiment, the SB gap G refers to the shortest distance between the maximum image area of the developing sleeve 70 and the maximum image area of the doctor blade 36. The maximum image area of the developing sleeve 70 refers to an area of the developing sleeve 70 with respect to the direction of the rotational axis of the developing sleeve 70 corresponding to the maximum image area in which an image can be formed on the surface of the photosensitive drum 1 (i.e., the maximum image area of the developing sleeve 70). Further, the maximum image area of the doctor blade 36 refers to an area of the doctor blade 36 corresponding to the maximum image area of the photosensitive drum 1 with respect to a direction parallel to the rotational axis of the developing sleeve 70 (i.e., the maximum image area of the doctor blade 36). In the first exemplary embodiment, the photosensitive drum 1 forms electrostatic latent images having a plurality of sizes such that the maximum image area refers to an image area corresponding to the maximum size (for example, a3 size) among the image areas of a plurality of sizes that can be formed on the photosensitive drum 1. On the other hand, in the modified example in which the photosensitive drum 1 forms only an electrostatic latent image of a single size, the maximum image area refers to an image area of a single size that can be formed on the photosensitive drum 1.

The doctor blade 36 is disposed substantially opposite to the peak position of the magnetic flux density of the magnetic pole of the magnet roller. The developer supplied to the developing sleeve 70 is influenced by the magnetic field generated by the magnetic pole of the magnetic roller. Further, the developer regulated and removed by the doctor blade 36 may accumulate in an upstream portion of the SB gap G. Therefore, a developer pool is formed upstream of the doctor blade 36 in the rotational direction of the developing sleeve 70. Then, as the developing sleeve 70 rotates, a part of the developer in the developer pool is conveyed so as to pass through the SB gap G. At this time, the layer thickness of the developer passing through the SB gap G is regulated by the coating amount regulating surface 36r of the doctor blade 36. In this way, a thin developer layer is formed on the surface of the developing sleeve 70.

Then, as the developing sleeve 70 rotates, a predetermined amount of the developer carried on the surface of the developing sleeve 70 is conveyed to the developing area. Therefore, the amount of developer conveyed to the development area is adjusted by adjusting the size of the SB gap G. In the first exemplary embodiment, the target size of the SB gap G (i.e., the target value of the SB gap G) is set to about 300 μm in the adjustment of the size of the SB gap G.

The developer conveyed to the development area is magnetically raised in the development area, thereby forming a magnetic brush. The magnetic brush is in contact with the photosensitive drum 1, thereby supplying toner contained in the developer to the photosensitive drum 1. Then, the electrostatic latent image formed on the surface of the photosensitive drum 1 is developed as a toner image. The developer on the surface of the developing sleeve 70 after the developer passes through the developing region and the toner is supplied to the photosensitive drum 1 (hereinafter referred to as "developer after the developing step") is removed from the surface of the developing sleeve 70 by a repulsive magnetic field formed between the magnetic poles of the magnet rollers having the same polarity. The developer after the developing step removed from the surface of the developing sleeve 70 falls into the developing chamber 31, and is thereby collected in the developing chamber 31.

As shown in fig. 4, the developing frame 30 is provided with a developer guiding portion 35 for guiding the developer so as to convey the developer toward the SB gap G. The developer guide portion 35 and the developing frame 30 are integrally formed, and the developer guide portion 35 and the doctor blade 36 are separately formed. The developer guiding portion 35 is formed in the developing frame 30, and is arranged upstream of the coating amount regulating surface 36r of the doctor blade 36 in the rotational direction of the developing sleeve 70. The flow of the developer is stabilized and adjusted to a predetermined developer concentration by the developer guiding portion 35 so that the weight of the developer at a position where the distance of the coating amount metering surface 36r of the doctor blade 36 from the surface of the developing sleeve 70 is minimized is determined.

Further, as shown in fig. 4, the cover frame 40 is formed separately from the developing frame 30, and is attached to the developing frame 30. Further, the cover frame 40 covers a part of the opening of the developing frame 30 so as to cover a part of the outer peripheral surface of the developing sleeve 70 over the entire area of the developing sleeve 70 in the longer side direction of the developing sleeve 70. At this time, the cover frame 40 covers a part of the opening of the developing frame 30 so as to expose the developing area of the developing sleeve 70 facing the photosensitive drum 1. The cover frame 40 is fixed to the developing frame 30 by ultrasonic bonding. Alternatively, the cover frame 40 may be fixed to the developing frame 30 by screw fastening, snap fitting, bonding, or welding.

(Structure of ink scraping blade made of resin)

The structure of the doctor blade 36 (single article) will be described below with reference to the perspective view shown in fig. 5.

During the image forming operation (developing operation), a pressure of the developer (hereinafter referred to as "reagent pressure") generated by the flow of the developer is applied to the doctor blade 36. Since the rigidity of the doctor blade 36 is low, the doctor blade 36 is more likely to be deformed when the reagent pressure is applied to the doctor blade 36 during the image forming operation, and the size of the SB gap G is more likely to fluctuate. During the image forming operation, the reagent pressure is applied in the shorter side direction (the direction of arrow M in fig. 5) of the doctor blade 36. Therefore, in order to prevent fluctuations in the size of the SB gap G during the image forming operation, it is desirable to increase the rigidity of the ink scraping blade 36 in the shorter side direction so that the ink scraping blade 36 is reinforced against deformation in the shorter side direction.

As shown in fig. 5, the shape of the doctor blade 36 is plate-shaped from the viewpoint of mass production and cost. Further, as shown in fig. 5, the cross-sectional area of the side surface 36t of the doctor blade 36 is set small, and the length t of the doctor blade 36 in the thickness direction of the doctor blade 36₂Is set to be longer than the length t of the doctor blade 36 in the shorter side direction of the doctor blade 36₁Is small. This enables the doctor blade 36 (single piece) to be opposed to the direction (fig. 5) orthogonal to the longer-side direction (the direction of arrow N in fig. 5) of the doctor blade 36In the direction of arrow M). Therefore, in order to correct the flatness of the coating amount metering surface 36r, the doctor blade 36 is fixed to the blade attachment portion 41 of the developing frame 30 in a state where at least a part of the doctor blade 36 is warped in the direction of the arrow M in fig. 5. Details of the correction of the straightness of the doctor blade 36 will be described below with reference to fig. 9.

(Structure of developing frame made of resin)

The structure of the developing frame 30 (single article) will be described below with reference to the perspective view shown in fig. 6. Fig. 6 shows a state in which the cover frame 40 is not attached to the developing frame 30.

The developing frame 30 includes a developing chamber 31 and an agitating chamber 32 separated from the developing chamber 31 by a partition wall 38. The partition wall 38 is resin-molded, and may be formed separately from the developing frame 30 or integrally with the developing frame 30.

The developing frame 30 includes a sleeve supporting portion 42 for rotatably supporting the developing sleeve 70 by supporting bearings 71 provided at respective end portions of the developing sleeve 70. Further, the developing frame 30 includes a blade attachment portion 41 for attaching the ink scraping blade 36, and the blade attachment portion 41 is integrally formed with the sleeve support portion 42. Fig. 6 shows a virtual state in which the ink scraping blade 36 is separated from the blade attachment portion 41 and suspended.

In a state where the ink scraping blade 36 is attached to the blade attachment portion 41, the adhesive a applied to the blade attachment surface 41s of the blade attachment portion 41 is hardened, so that the ink scraping blade 36 is fixed to the blade attachment portion 41. Details of steps of a method of incorporating the doctor blade 36 according to the first exemplary embodiment will be described below with reference to fig. 14, 16, and 17.

(rigidity of ink scraping blade made of resin)

The rigidity of the doctor blade 36 (single piece) will be described below with reference to the schematic diagram shown in fig. 7. The rigidity of the doctor blade 36 (single piece) is measured in a state where the doctor blade 36 is not fixed to the blade attachment portion 41 of the developing frame 30.

As shown in fig. 7, a concentrated load F1 is applied in the shorter side direction of the ink scraping blade 36 with respect to the central portion 36z of the ink scraping blade 36 in the longer side direction of the ink scraping blade 36. At this time, the rigidity of the doctor blade 36 (single piece) is measured based on the amount of warp at the central portion 36z of the doctor blade 36 in the shorter side direction of the doctor blade 36.

For example, a concentrated load F1 of 300gf is applied in the shorter side direction of the ink scraping blade 36 with respect to the center portion 36z of the ink scraping blade 36 in the longer side direction of the ink scraping blade 36. At this time, the amount of warp at the central portion 36z of the ink scraping blade 36 in the shorter side direction of the ink scraping blade 36 is 700 μm or more, and the amount of deformation of the central portion 36z of the ink scraping blade 36 in the cross section is 5 μm or less.

(rigidity of developing frame made of resin)

The rigidity of the developing frame 30 (single article) will be described below with reference to the schematic view shown in fig. 8. The rigidity of the developing frame 30 (single article) was measured in a state where the doctor blade 36 was not fixed to the blade attachment portion 41 of the developing frame 30.

As shown in fig. 8, a concentrated load F1 is applied in the shorter side direction of the blade attachment portion 41 at the center portion 41z in the longer side direction of the blade attachment portion 41 with respect to the blade attachment portion 41. At this time, the rigidity of the developing frame 30 (single article) is measured based on the amount of warping at the center portion 41z of the blade attachment portion 41 in the shorter side direction of the blade attachment portion 41.

For example, a concentrated load F1 of 300gf is applied in the shorter side direction of the blade attachment portion 41 at the center portion 41z of the blade attachment portion 41 in the longer side direction of the blade attachment portion 41 with respect to the blade attachment portion 41. At this time, the amount of warping at the center portion 41z of the blade attachment portion 41 in the shorter side direction of the blade attachment portion 41 is 60 μm or less.

The same concentrated load F1 is applied to the central portion 36z of the doctor blade 36 and to the central portion 41z of the blade attachment portion 41 of the developing frame 30. At this time, the amount of warp at the central portion 36z of the ink scraping blade 36 is ten times or more the amount of warp at the central portion 41z of the blade attachment portion 41. Therefore, the rigidity of the developing frame 30 (single piece) is ten times or more the rigidity of the doctor blade 36 (single piece). Therefore, in a state where the ink scraping blade 36 is attached and fixed to the blade attachment portion 41 of the developing frame 30, the rigidity of the developing frame 30 becomes dominant with respect to the rigidity of the ink scraping blade 36. Further, the rigidity of the ink scraping blade 36 fixed to the developing frame 30 is higher in the case where the ink scraping blade 36 is fixed to the developing frame 30 over the entire maximum image area thereof than in the case where the ink scraping blade 36 is fixed to the developing frame 30 only in the longer-side direction thereof at the respective end portions of the ink scraping blade 36.

Further, the rigidity of the developing frame 30 (single piece) is higher than that of the cover frame 40 (single piece). Therefore, in a state where the cover frame 40 is attached and fixed to the developing frame 30, the rigidity of the developing frame 30 becomes dominant with respect to the rigidity of the cover frame 40.

(correction of flatness of the doctor blade made of resin)

As the width of the sheet S on which an image is to be formed (for example, the width of the sheet S is a3 size) increases, the length of the maximum image area in which an image can be formed on the surface of the photosensitive drum 1 increases in a direction parallel to the rotational axis of the developing sleeve 70. Therefore, as the width of the sheet S on which an image is to be formed increases, the length of the maximum image area of the doctor blade 36 increases. In the case of resin molding a doctor blade extending in the longer-side direction, it is difficult to ensure the flatness of the coating amount regulating surface of the resin-molded doctor blade made of resin. This is because in the case of resin molding a doctor blade extending in the longer-side direction, when the resin after thermal expansion thermally contracts, the thermal contraction progresses faster at some positions in the longer-side direction of the doctor blade, and the thermal contraction progresses slower at some other positions in the longer-side direction of the doctor blade.

Therefore, in the resin doctor blade, as the length of the doctor blade in the longer side direction becomes longer, the SB gap is more likely to vary in the longer side direction of the developer carrying member due to the flatness of the coating amount regulating surface of the doctor blade. If the SB gap varies in the longer side direction of the developer carrying member, the amount of developer carried on the surface of the developer carrying member in the longer side direction of the developer carrying member may also vary.

For example, in the case of manufacturing a resin doctor blade having a length capable of supporting an A3 size in a longer side direction (hereinafter referred to as "A3-size-supported resin doctor blade") with the usual accuracy of a resin molded article, the flatness of the coating burette control surface is about 300 μm to 500 μm. Further, even if the resin doctor blade supporting the a3 size is manufactured with high accuracy using a high-accuracy resin material, the flatness of the coating amount regulating surface is about 100 μm to 200 μm.

In the first exemplary embodiment, the size of the SB gap G is set to about 300 μm, and the tolerance of the SB gap G (specifically, the tolerance of the SB gap G with respect to a target value) is set to ± 10% or less. This shows that in the first exemplary embodiment, the adjustment range of the SB gap G is 300 μm ± 30 μm, and the maximum allowable tolerance of the SB gap G is as high as 60 μm. Therefore, regardless of whether the resin doctor blade supporting the a3 size is manufactured with the usual precision of resin molded articles or with high precision using high-precision resin materials, the precision of the flatness of the single-coating-amount regulating surface exceeds the allowable tolerance range of the SB gap G.

A developing device including a doctor blade made of resin is expected to satisfy the following conditions. Specifically, in a state where the doctor blade is fixed to the attachment portion of the developing frame, the SB gap G is desirably in a predetermined range in a direction parallel to the rotation axis of the developer carrying member, regardless of the flatness of the coating amount regulating surface of the resin doctor blade. Therefore, in the first exemplary embodiment, if the flatness is low, the flatness of the coating amount regulating surface of the resin doctor blade is corrected. In this way, even if the doctor blade made of resin and including the coating amount regulating surface having low flatness is used, the SB gap G is adjusted to be within a predetermined range in a direction parallel to the rotational axis of the developing sleeve 70 in a state where the doctor blade is fixed to the attachment portion of the developing frame.

The flatness of the coating amount regulating surface 36r of the doctor blade 36 will be described below with reference to a schematic view shown in fig. 9. The flatness of the coating amount regulating surface 36r is specified by an absolute value of a difference between a maximum value and a minimum value of the outer shape of the coating amount regulating surface 36r using a predetermined portion of the coating amount regulating surface 36r in the longer side direction of the coating amount regulating surface 36r as a reference. For example, the central portion of the coating quantity metering surface 36r in the longer side direction of the coating quantity metering surface 36r is determined as the origin of the orthogonal coordinate system, and a predetermined straight line passing through the origin is determined as the X-axis, and a straight line drawn perpendicularly to the X-axis from the origin is determined as the Y-axis. On the orthogonal coordinate system, the flatness of the coating metering tube controlling surface 36r is specified by the absolute value of the difference between the maximum value and the minimum value of the profile of the coating metering tube controlling surface 36 r.

As shown in fig. 9, the coating quantity metering surface 36r of the resin doctor blade 36 (single article) is warped significantly at the central portion of the coating quantity metering surface 36r in the longer side direction of the doctor blade 36. Therefore, it is necessary to correct the straightness of the coating quantity metering surface 36r by reducing the difference between the positions of the leading edge portions 36e (36e1 to 36e5) of the doctor blade 36 in fig. 5. In view of the allowable value of the tolerance of the SB gap G and the attachment accuracy of the doctor blade 36 with respect to the developing frame 30, it is necessary to correct the flatness of the coating amount regulating surface 36r of the doctor blade 36 to 50 μm or less. Since the accuracy of the flatness of the doctor blade made of metal by the secondary cutting is 20 μm or less, it is more desirable to correct the flatness of the coating amount regulating surface 36r of the resin doctor blade 36 to 20 μm or less. The corrected setting value of the flatness of the coating amount regulating surface 36r of the doctor blade 36 is set to about 20 μm to 50 μm in view of an actual mass production process.

For this reason, a force for warping at least a part of the maximum image area of the doctor blade 36 (also referred to as "flatness correction force") is applied to the doctor blade 36 so that at least a part of the maximum image area of the doctor blade 36 is warped. In this way, the flatness of the coating amount regulating surface 36r of the doctor blade 36 is corrected to 50 μm or less.

In the example shown in fig. 9, the profiles of the leading edge portions 36e1 and 36e5 of the doctor blade 36 are determined as references, and the straightness correcting force is applied in the direction of arrow I in fig. 9 with respect to the leading edge portions 36e2, 36e3, and 36e4 in such a manner that the profiles of the leading edge portions 36e2, 36e3, and 36e4 are adjusted to the references. Therefore, the shape of the coating amount regulating surface 36r of the doctor blade 36 is corrected from the coating amount regulating surface 36r1 to the coating amount regulating surface 36r2, so that the flatness of the coating amount regulating surface 36r of the doctor blade 36 is corrected to 50 μm or less. Although the profiles of the leading edge portions 36e1 and 36e5 (the respective end portions of the coating quantity metering surface 36r in the longer-side direction of the coating quantity metering surface 36 r) are determined as references for adjustment of the profile of the leading edge portion 36e of the doctor blade 36 in the example shown in fig. 9, the profile of the leading edge portion 36e3 (the central portion of the coating quantity metering surface 36r in the longer-side direction of the coating quantity metering surface 36 r) may also be determined as a reference. In this case, the profile of the leading edge portion 36e3 of the doctor blade 36 is used as a reference, and the straightness correcting force is applied to the doctor blade 36 in such a manner that the profiles of the leading edge portions 36e1, 36e2, 36e4, and 36e5 are adjusted to the reference.

As described above, in order to correct the flatness of the doctor blade 36, it is necessary to reduce the rigidity of the doctor blade 36 (single article) in such a manner that at least a part of the maximum image area of the coating metering tube surface 36r warps when the flatness correction force is applied to the doctor blade 36.

(method of adjusting SB gap)

The SB gap G is adjusted by moving the position of the ink scraping blade 36 relative to the developing frame 30 so as to adjust the relative position of the ink scraping blade 36 attached to the blade attachment portion 41 relative to the developing sleeve 70 supported by the sleeve supporting portion 42. The doctor blade 36 (in which at least a part of the maximum image area of the doctor blade 36 is warped) is fixed to a predetermined position of the blade attachment portion 41 determined by the adjustment of the SB gap G using the adhesive a applied to the entire maximum image area of the blade attachment surface 41s in advance.

The maximum image area of the blade attachment surface 41s refers to an area of the blade attachment surface 41s corresponding to a maximum image area in which an image can be formed on the surface of the photosensitive drum 1 in a direction parallel to the rotational axis of the developing sleeve 70. At this time, a region of the doctor blade 36 warped to correct the straightness of the coating quantity metering surface 36r in the maximum image region of the doctor blade 36 is fixed to the blade attachment portion 41.

In the case where the area on which the force for warping at least a part of the maximum image area of the doctor blade 36 is applied is fixed to the blade attachment portion 41 using the adhesive a, the adhesive a need not be applied to a part of the blade attachment surface 41 s. Therefore, the state where the adhesive a is applied on the entire maximum image area of the blade attachment surface 41s is a state where the following condition is satisfied. Specifically, the adhesive a is applied to 95% or more of the maximum image area of the blade attachment surface 41s (including an area warped to correct the flatness of the coating amount metering surface 36r in the area corresponding to the maximum image area of the doctor blade 36) when the doctor blade 36 is attached to the blade attachment portion 41.

In this way, the region warped in the maximum image region of the doctor blade 36 to correct the straightness of the coating amount metering surface 36r is prevented from returning from the warped state to the original state before the warping. In this way, the doctor blade 36 is fixed to the blade attachment portion 41 in a state where the flatness of the coating amount metering surface 36r is corrected to 50 μm or less.

The size of SB gap G was measured (calculated) using the method described below. The size of the SB gap G is measured in a state where the developing sleeve 70 is supported by the sleeve supporting portion 42 of the developing frame 30 and the doctor blade 36 is attached to the blade attaching portion 41 of the developing frame 30 while the cover frame 40 is fixed to the developing frame 30.

Before measuring the SB gap G, a light source (e.g., a light emitting unit such as a Light Emitting Diode (LED) array and a light guide) is inserted into the developing chamber 31 in a longer side direction of the developing chamber 31. The light source inserted into the developing chamber 31 emits light from the inside of the developing chamber 31 toward the SB gap G. Further, a camera (light receiving unit) is provided at each of five positions corresponding to the leading edge portion 36e (36e1 to 36e5) of the doctor blade 36. The camera captures a light beam emitted to the outside of the development frame 30 through the SB gap G.

The cameras provided at five positions capture light beams emitted to the outside of the developing frame 30 through the SB gap G to measure the positions of the leading edge portions 36e (36e1 to 36e5) of the doctor blade 36. At this time, the camera reads the position on the surface of the developing sleeve 70 where the distance of the developing sleeve 70 from the doctor blade 36 is minimized and the positions of the leading edge portions 36e (36e1 to 36e5) of the doctor blade 36. Then, the pixel values of the image data read and generated by the camera are converted into distances, and the size of the SB gap G is calculated. In the case where the calculated dimension of the SB gap G is not within the predetermined range, the SB gap G is adjusted. Then, if the calculated size of the SB gap G is within a predetermined range, the position is determined as the position at which the doctor blade 36 (in which at least a part of the maximum image area of the doctor blade 36 is warped) is to be fixed to the blade attachment portion 41 of the developing frame 30.

Whether the SB gap G is within a predetermined range in a direction parallel to the rotational axis of the developing sleeve 70 is determined using the following method. First, the maximum image area of the ink scraping blade 36 is equally divided into four or more, and the SB gap G is measured at five or more positions in each divided portion of the ink scraping blade 36 (including the respective end portions and the central portion of the maximum image area of the ink scraping blade 36). Then, the maximum value, the minimum value, and the median value of the SB gap G are extracted from a sample of the measured values of the SB gap G measured at five or more positions.

At this time, the absolute value of the difference between the maximum value of the SB gap G and the median value of the SB gap G is desirably 10% or less of the median value of the SB gap G, and the absolute value of the difference between the minimum value of the SB gap G and the median value of the SB gap G is desirably 10% or less of the median value of the SB gap G. In this case, the tolerance of the SB gap G is ± 10% or less, and the condition that the SB gap G is within a predetermined range in the direction parallel to the rotational axis of the developing sleeve 70 is satisfied. For example, in the case where the median value of SB gaps G extracted from a sample of measured values of SB gaps G measured at five or more positions is 300 μm, the maximum value of SB gaps G is desirably 330 μm or less, and the minimum value of SB gaps G is desirably 270 μm or more. Specifically, in this case, the adjustment range of the SB gap G is 300 μm ± 30 μm, and the maximum allowable tolerance of the SB gap G is 60 μm.

(coefficient of Linear expansion)

Next, the deformation of the doctor blade 36 and the developing frame 30 due to a temperature change caused by heat generated during an image forming operation will be described below with reference to a perspective view shown in fig. 10. Examples of the heat generated during the developing operation include heat generated during rotation of the rotary shaft of the developing sleeve 70 and the bearing 71, heat generated during rotation of the rotary shaft 33a of the first conveyance screw 33 and the bearing member, and heat generated when the developer passes through the SB gap G. The temperature around the developing device 3 is changed by the heat generated during the image forming operation, and the temperatures of the doctor blade 36, the developing frame 30, and the cover frame 40 are also changed.

Fig. 10 shows an expansion amount H [ μm ] of the ink scraping blade 36 caused by a temperature change and an expansion amount I [ μm ] of the blade attaching surface 41s of the blade attaching portion 41 of the developing frame 30 caused by a temperature change. Further, it is assumed that the linear expansion coefficient α 1 of the resin forming the doctor blade 36 and the linear expansion coefficient α 2 of the resin forming the developing frame 30 are different from each other. In this case, the deformation amount of the developing frame 30 due to the temperature change and the deformation amount of the doctor blade 36 due to the temperature change are different from each other due to the difference in the linear expansion coefficient, and in order to reduce the difference between the expansion amounts H [ μm ] and I [ μm ], the doctor blade 36 is deformed in the direction of the arrow J in fig. 10. Hereinafter, the deformation of the doctor blade 36 in the direction of the arrow J in fig. 10 will be referred to as "deformation of the doctor blade 36 in the warping direction". Further, the deformation of the doctor blade 36 in the warp direction causes fluctuation in the size of the SB gap G. In order to prevent fluctuation in the size of the SB gap G caused by heat, the linear expansion coefficient α 2 of the resin forming the sleeve supporting portion 42 and the blade attaching portion 41 of the developing frame 30 (single piece) and the linear expansion coefficient α 1 of the resin forming the ink scraping blade 36 (single piece) are associated with each other. Specifically, in the case where the linear expansion coefficient α 1 of the resin forming the doctor blade 36 and the linear expansion coefficient α 2 of the resin forming the developing frame 30 are different, the deformation amounts caused by the temperature change are different from each other due to the difference in the linear expansion coefficients α 1 and α 2.

In general, the linear expansion coefficient of the resin material is larger than that of the metal material. In the case where the ink scraping blade 36 is made of resin, a temperature change caused by heat generated during an image forming operation causes the ink scraping blade 36 to warp or deform, and a central portion in a longer side direction of the ink scraping blade 36 is likely to warp. Therefore, during an image forming operation in a developing device in which the resin doctor blade 36 is fixed to the resin developing frame 30, the size of the SB gap G is likely to fluctuate due to temperature changes.

In order to correct the flatness of the coating amount metering surface 36r to 50 μm or less, at least a part of the maximum image area of the doctor blade 36 is warped. Further, the doctor blade 36 (in which at least a part of the maximum image area of the doctor blade 36 is warped) is fixed to the blade attachment portion 41 of the developing frame 30 using the adhesive a over the entire maximum image area of the doctor blade 36.

At this time, if the linear expansion coefficient α 2 of the resin forming the developing frame 30 and the linear expansion coefficient α 1 of the resin forming the doctor blade 36 are significantly different, the following occurs when a temperature change occurs. Specifically, when a temperature change occurs, the deformation amount (expansion/contraction amount) of the doctor blade 36 caused by the temperature change and the deformation amount (expansion/contraction amount) of the developing frame 30 caused by the temperature change are different from each other. Therefore, even if the SB gap G is adjusted with high accuracy when determining the position at which the doctor blade 36 is to be attached to the blade attachment surface 41s of the developing frame 30, temperature variations during the image forming operation cause fluctuations in the size of the SB gap G.

The ink scraping blade 36 is fixed to the blade attachment surface 41s over the entire maximum image area, so that it is necessary to prevent fluctuations in the size of the SB gap G caused by temperature changes during image forming operations. The fluctuation amount of the SB gap G caused by heat generally needs to be reduced to ± 20 μm or less in order to prevent variation in the amount of the developer carried on the surface of the developing sleeve 70 in the longer side direction of the developing sleeve 70.

Hereinafter, the difference between the linear expansion coefficient α 2 of the resin forming the developing frame 30 including the sleeve supporting portion 42 and the blade attaching portion 41 and the linear expansion coefficient α 1 of the resin forming the doctor blade 36 will be referred to as "linear expansion coefficient difference α 2- α 1". The change in the maximum amount of the warp of the doctor blade 36 due to the difference in the linear expansion coefficients α 2- α 1 will be described below with reference to table 1. In a state where the doctor blade 36 is fixed to the blade attachment portion 41 of the developing frame 30 over the entire maximum image area of the doctor blade 36, the maximum amount of warpage of the doctor blade 36 is measured when the temperature changes from room temperature (23 ℃) to high temperature (40 ℃).

The linear expansion coefficient of the resin forming the developing frame 30 including the sleeve supporting portion 42 and the blade attaching portion 41 is represented by α 2[ m/° c ], and the linear expansion coefficient of the resin forming the ink scraping blade 36 is represented by α 1[ m/° c ]. Table 1 indicates the results of measuring the maximum amount of warpage of the doctor blade 36 using the variation parameter of the difference in linear expansion coefficient α 2- α 1. In table 1, in the case where the absolute value of the maximum amount of warpage of the doctor blade 36 is 20 μm or less, the maximum amount of warpage is "good", whereas in the case where the absolute value of the maximum amount of warpage of the doctor blade 36 exceeds 20 μm, the maximum amount of warpage is "bad".

TABLE 1

As can be understood from table 1, in order to reduce the fluctuation amount of the SB gap G caused by heat to ± 20 μm or less, the linear expansion coefficient difference α 2 — α 1 needs to satisfy the following relational expression.

-0.45×10^-5[m/℃]≤α2-α1≤0.55×10^-5[m/℃](formula 1)

Therefore, the resin forming the developing frame 30 and the resin forming the doctor blade 36 may be selected so that the difference in linear expansion coefficient α 2- α 1 is-0.45 × 10^-5[m/℃]Above and 0.55X 10^-5[m/℃]The following. In selecting the same resin as the resin forming the developing frame 30 and the resin forming the doctor blade 36In the case of fat, the difference in linear expansion coefficient α 2- α 1 becomes zero.

If the adhesive a is applied to the developing frame 30, the linear expansion coefficient of the developing frame 30 to which the adhesive a is applied is changed. However, the volume of the adhesive a applied to the developing frame 30 is small enough to ignore the influence of temperature change on dimensional fluctuation in the thickness direction of the adhesive a. Therefore, the deformation in the warping direction of the doctor blade 36 caused by the variation in the difference in the linear expansion coefficients α 2- α 1 in the case where the adhesive a is applied to the developing frame 30 can be ignored.

Similarly, the cover frame 40 is fixed to the developing frame 30 such that if the amount of deformation of the developing frame 30 caused by the temperature change and the amount of deformation of the cover frame 40 caused by the temperature change are different from each other, the deformation in the warping direction of the cover frame 40 thereby causes the fluctuation in the size of the SB gap G. The linear expansion coefficient of the resin forming the developing frame 30 including the sleeve supporting portion 42 and the blade attaching portion 41 is represented by α 2[ m/° c ], and the linear expansion coefficient of the resin of the cover frame 40 is represented by α 3[ m/° c ]. Hereinafter, the difference between the linear expansion coefficient α 2 of the resin forming the developing frame 30 including the sleeve supporting portion 42 and the blade attaching portion 41 and the linear expansion coefficient α 3 of the resin forming the cover frame 40 will be referred to as "linear expansion coefficient difference α 3- α 2". At this time, the linear expansion coefficient difference α 3 — α 2 needs to satisfy the following relational expression (expression 2) as in table 1.

-0.45×10^-5[m/℃]≤α3-α2≤0.55×10^-5[m/℃](formula 2)

Therefore, the resin forming the developing frame 30 and the resin forming the cover frame 40 may be selected such that the difference in linear expansion coefficient α 3- α 2 is-0.45 × 10^-5[m/℃]Above and 0.55X 10^-5[m/℃]The following. In the case where the same resin is selected as the resin forming the developing frame 30 and the resin forming the cover frame 40, the difference in linear expansion coefficient α 3- α 2 becomes zero.

(pressure of reagent)

Next, deformation of the doctor blade 36 caused by application of a reagent pressure generated by flow of the developer to the doctor blade 36 during an image forming operation will be described below with reference to a sectional view shown in fig. 11. Fig. 11 is a sectional view showing the developing device 3 along a cross section (cross section H in fig. 2) orthogonal to the rotation axis of the developing sleeve 70. Further, fig. 11 shows a structure in the vicinity of the ink scraping blade 36 fixed to the blade attachment portion 41 of the developing frame 30 with the adhesive a.

As shown in fig. 11, a line connecting the closest position of the doctor blade 36 to the coating quantity metering surface 36r with respect to the developing sleeve 70 and the rotation center of the developing sleeve 70 is determined as the X-axis. At this time, the doctor blade 36 extends in the X-axis direction, and has high rigidity of the cross section in the X-axis direction. Further, as shown in fig. 11, the cross-sectional area T1 of the doctor blade 36 is small in proportion to the cross-sectional area T2 of the wall portion 30a of the developing frame 30 positioned in the vicinity of the developer guiding portion 35.

As described above, the rigidity of the developing frame 30 (single article) is ten times or more the rigidity of the doctor blade 36 (single article). Therefore, in a state where the ink scraping blade 36 is fixed to the blade attachment portion 41 of the developing frame 30, the rigidity of the developing frame 30 becomes dominant with respect to the rigidity of the ink scraping blade 36. Therefore, the displacement amount (the maximum amount of warp) of the coating amount regulating surface 36r of the doctor blade 36 when the reagent pressure is applied to the doctor blade 36 during the image forming operation is substantially equal to the displacement amount (the maximum amount of warp) of the developing frame 30.

During an image forming operation, the developer drawn from the first conveyance screw 33 passes through the developer guide portion 35, and is conveyed to the surface of the developing sleeve 70. After that, when the layer thickness of the developer is regulated by the doctor blade 36 in accordance with the size of the SB gap G, the doctor blade 36 receives the reagent pressure from each direction. As shown in fig. 11, when the direction orthogonal to the X-axis direction (the direction defining the SB gap G) is the Y-axis direction, the reagent pressure in the Y-axis direction is perpendicular to the blade attachment surface 41s of the developing frame 30. Specifically, the reagent pressure in the Y-axis direction is a force in a direction of peeling the ink scraping blade 36 from the blade attachment surface 41 s. Therefore, the bonding force of the adhesive a needs to be sufficiently stronger than the reagent pressure in the Y-axis direction. Therefore, in optimizing the area and thickness of the adhesive a to be bonded and applied to the blade attachment surface 41s, the force of the bonding force of the adhesive a and the pressure of the reagent that peels the ink-scraping blade 36 from the blade attachment surface 41s are taken into consideration.

(method of incorporating a doctor blade made of resin)

As described above, as the width of the sheet S on which an image is to be formed increases, the length of the maximum image area of the doctor blade 36 in the longer-side direction increases. In the case where the resin molds the ink blade 36 extending in the longer-side direction, the thermal shrinkage rate of the resin after thermal expansion generally varies in the longer-side direction of the ink blade 36. Therefore, in the case where the doctor blade 36 extending in the longer-side direction is resin-molded with the usual accuracy of resin-molded articles, it is difficult to ensure the flatness of the coating amount regulating surface 36r of the resin-molded doctor blade 36.

Therefore, in the first exemplary embodiment, at least a part of the maximum image area of the doctor blade 36 is warped so as to correct the flatness of the coating amount regulating surface 36r of the doctor blade 36 extending in the longer-side direction to 50 μm or less. Then, the doctor blade 36 (in which at least a part of the maximum image area of the doctor blade 36 is warped) is attached and fixed to the blade attachment portion 41 using the adhesive a. In this way, the region warped in the maximum image region of the doctor blade 36 to correct the straightness of the coating amount metering surface 36r is prevented from returning from the warped state to the original state before the warping. In order to prevent the ink scraping blade 36 from returning to the original state from the warped state, it is desirable to fix the ink scraping blade 36 to the blade attachment portion 41 using the adhesive a over the entire maximum image area of the ink scraping blade 36. In order to fix the ink blade 36 in a warped state using the adhesive a over the entire maximum image area of the blade attachment portion 41, the adhesive a needs to be applied over the entire maximum image area of the blade attachment surface 41 s.

In the first exemplary embodiment, the ink scraping blade 36 is attached and fixed to the blade attachment portion 41 using the adhesive a. In such a configuration, the adhesive a having a predetermined layer thickness is applied to the blade attachment surface 41 s. There is an adhesive applying apparatus configured to apply the adhesive a to the blade attaching surface 41s by moving an adhesive applying unit (e.g., a dispenser having a nozzle) in the longer-side direction. In the case of using such an adhesive applying apparatus, the layer thickness of the adhesive a applied to the blade attaching surface 41s by the adhesive applying apparatus varies in the longer-side direction of the blade attaching surface 41s with the usual accuracy of the adhesive applying apparatus.

If the length of the maximum image area of the ink scraping blade 36 in the longer-side direction increases as the width of the sheet S on which an image is to be formed increases, the length of the maximum image area of the blade attachment surface 41S to which the ink scraping blade 36 is attached in the longer-side direction also increases. Further, as the length of the maximum image area of the blade attachment surface 41s in the longer side direction becomes longer, the layer thickness of the adhesive a applied to the blade attachment surface 41s by the adhesive applying apparatus is more likely to vary in the longer side direction of the blade attachment surface 41 s.

The length of time required for the adhesive to harden so as to obtain sufficient bonding strength of the doctor blade 36 with respect to the blade attachment surface 41s (hereinafter simply referred to as "adhesive hardening time") is proportional to the layer thickness of the adhesive a. In other words, the adhesive hardening time becomes longer as the layer thickness of the adhesive a is thicker, and the adhesive hardening time becomes shorter as the layer thickness of the adhesive a is thinner. Therefore, if the layer thickness of the adhesive a applied to the blade attachment surface 41s varies in the longer-side direction of the blade attachment surface 41s, the adhesive hardening time of the adhesive a applied to the blade attachment surface 41s varies in the longer-side direction of the blade attachment surface 41 s. The case where the adhesive applying apparatus applies the adhesive a to the blade attachment surface 41s to which the ink blade 36 extending in the longer-side direction is to be attached, over the entire maximum image area of the blade attachment surface 41s will be discussed below. In this case in particular, the adhesive hardening time of the adhesive a is likely to vary significantly in the longer-side direction of the blade attachment surface 41 s.

Further, in the case of using a common adhesive (e.g., a cyanoacrylate-based adhesive), it may take about one minute or only about one second to sufficiently harden the adhesive to obtain sufficient bonding strength, so that there is also a factor of variation in the precision of the adhesive material.

In the case where the adhesive hardening time significantly varies in the longer side direction of the blade attachment surface 41s, when a predetermined time elapses after the adhesive a is applied, the adhesive a is sufficiently hardened at some portions in the longer side direction of the blade attachment surface 41s, but is not sufficiently hardened at some other portions. The apparatus applies a predetermined pressure to the ink scraping blade 36 when bonding the ink scraping blade 36 to the blade attachment surface 41s to which the adhesive a is applied. In the case where the adhesive is sufficiently hardened at some portions and not sufficiently hardened at some other portions in the longer side direction of the blade attachment surface 41s, it is necessary to set the length of time taken in the bonding step according to the portion where the adhesive a is not sufficiently hardened. Specifically, even if the adhesive a is sufficiently hardened at some portions, the apparatus continuously applies a predetermined pressure to the doctor blade 36 as long as there are some other portions where the adhesive a is not sufficiently hardened until the adhesive a at the portions where the adhesive a is not sufficiently hardened is also sufficiently hardened. Therefore, the possible variation in the layer thickness of the adhesive a applied to the blade attachment surface 41s by the adhesive applying apparatus is estimated in advance, and the length of time that will be taken in the bonding step in the process of manufacturing the developing apparatus 3 is set based on this.

From the viewpoint of mass production, it is desirable that the time taken in the bonding step in the process of manufacturing the developing device 3 is short, and it is also desirable that the adhesive hardening time in the bonding step is short. This is because if the adhesive hardening time is reduced, the tact time is shortened, which is advantageous from the viewpoint of mass production. As described above, the adhesive hardening time is determined based on the layer thickness of the applied adhesive a (specifically, the amount of the applied adhesive a).

Therefore, the amount of the adhesive to be applied to the blade attachment surface 41s by the adhesive applying device during the bonding step is set as described below. Specifically, as described above, in optimizing the bonding area and thickness of the adhesive a to be bonded and applied to the blade attachment surface 41s, the force of the bonding force of the adhesive a and the pressure of the reagent that peels the doctor blade 36 from the blade attachment surface 41s are taken into consideration. How to prevent the variation in the adhesive hardening time due to the variation in the layer thickness of the adhesive a applied to the blade attachment surface 41s in the case where a common adhesive material is used as the adhesive a and the amount of the adhesive a to be applied to the blade attachment surface 41s is set to an appropriate amount will be discussed below. Regarding the change in the adhesive hardening time, the longer the adhesive hardening time, the more the adhesive hardening time changes, and the shorter the adhesive hardening time, the less the adhesive hardening time changes. Therefore, in order to reduce variation in the adhesive hardening time in the case where the resin doctor blade 36 extending in the longer-side direction is fixed to the blade attachment portion 41 using the adhesive a, hardening of the adhesive may be accelerated using a hardening accelerator for accelerating the hardening of the adhesive. More specifically, the hardening accelerator is applied to the bonding surface of the doctor blade 36, and the adhesive a is applied to the blade attachment surface 41 s. In this way, when the ink scraping blade 36 is bonded to the blade attachment surface 41s, the adhesive a applied to the blade attachment surface 41s and the hardening accelerator applied to the bonding surface of the ink scraping blade 36 chemically react with each other to accelerate the hardening of the adhesive a.

In the first exemplary embodiment as described above, the SB gap is adjusted to be within a predetermined range in the longer side direction of the developer carrying member while preventing variation in adhesive hardening time when the resin doctor blade extending in the longer side direction is bonded to the developing frame made of resin. The details of this case will be described below.

(Binder)

In the first exemplary embodiment, in a state where the ink scraping blade 36 in a warped state is attached to the blade attachment portion 41, the adhesive a applied to the blade attachment surface 41s is hardened, so that the ink scraping blade 36 is fixed to the blade attachment portion 41 via the adhesive a. It is necessary to select the adhesive a having a sufficient bonding strength so that the doctor blade 36 is not detached from the blade attachment surface 41s of the developing frame 30 during the image forming operation (developing operation). The load applied to the ink scraping blade 36 during the image forming operation (developing operation) was about 2kgf in the drop test, and the ink scraping blade 36 was satisfactory if the ink scraping blade 36 was not separated from the blade attachment surface 41s of the developing frame 30 under a load equal to the above load. It is known that sufficient bonding strength can be obtained with the conventional adhesive a, and from the viewpoint of mass production, the shorter the hardening time of the adhesive, the better.

The layer thickness of the adhesive a applied to the blade attachment surface 41s of the developing frame 30 will be described below. Since the doctor blade 36 and the blade attachment surface 41s of the developing frame 30 are bonded together using the adhesive a, the adhesive a is located between the doctor blade 36 and the blade attachment surface 41s of the developing frame 30. Therefore, in order to prevent the adhesive a located between the doctor blade 36 and the blade attachment surface 41s of the developing frame 30 from affecting the size of the SB gap G, the layer thickness of the adhesive a to be applied to the blade attachment surface 41s needs to be carefully considered.

In the relationship between the layer thickness of the adhesive a and the breaking load of the portion bonded with the adhesive a, the larger the amount of the adhesive a, the higher the bonding strength of the adhesive a becomes. As described above, the load applied to the doctor blade 36 during the image forming operation (developing operation) was about 2kgf, and the required bonding strength of the adhesive a in the first exemplary embodiment was set to 10kgf or more (with a certain margin). In order to obtain a bonding strength of 10kgf or more as the bonding strength of the adhesive a, the layer thickness of the adhesive a applied to the blade attachment surface 41s of the developing frame 30 is desirably set to 20 μm or more.

Next, the relationship between the thickness of the adhesive a to be applied and dimensional fluctuation in the thickness direction of the adhesive a will be described below. In general, as the layer thickness of the adhesive a increases, dimensional fluctuation in the thickness direction of the adhesive a caused by shrinkage of the adhesive a during hardening of the adhesive a occurs. Meanwhile, the dimensional fluctuation in the thickness direction of the adhesive a in the case where the layer thickness of the adhesive a is 150 μm is only about 8 μm larger than that in the case where the layer thickness of the adhesive a is 30 μm. If the difference in dimensional fluctuation in the thickness direction of the adhesive a is about 8 μm, the influence of dimensional fluctuation in the direction orthogonal to the thickness direction of the adhesive a (specifically, the direction defining the SB gap G) can be ignored. Therefore, the upper limit of the layer thickness of the adhesive a to be applied to the blade attachment surface 41s of the developing frame 30 may be determined not based on the influence of the shrinkage of the adhesive a but based on individual production conditions (such as adhesive hardening time and cost).

The adhesive a must be selected to have sufficient bonding strength so that the doctor blade 36 is not peeled off during use. The load applied to the doctor blade 36 in the drop test was about 2kgf, and if the doctor blade 36 did not peel off under the load, the adhesive a was satisfactory. It is known that sufficient bonding strength is obtained with a conventional cyanoacrylate-based adhesive. Therefore, in the first exemplary embodiment, a description is given using an example in which a general cyanoacrylate-based adhesive is used as the adhesive a. The cyanoacrylate-based adhesive initiates a chain polymerization reaction using an alkaline material as a catalyst, and thus the cyanoacrylate-based adhesive is hardened by polymerization. The mechanism of hardening the cyanoacrylate-based adhesive will be described below.

Fig. 12 shows the chemical formula of the cyanoacrylate-based adhesive. As shown in fig. 12, the liquid cyanoacrylate-based adhesive is generally present in the form of a monomer. The hardening of cyanoacrylate-based adhesives indicates that the monomers cause chain polymerization and polymerization. In order for the monomer to cause chain polymerization, a catalyst for initiating the chain polymerization is required, and a basic material acts as the catalyst. Generally, the moisture content in the air functions as a catalyst. More specifically, although pure water (H)₂O) is neutral, but the moisture content in the air is weakly alkaline, since impurities are usually contained in the moisture content. Thus, the moisture content in air acts as a catalyst for the cyanoacrylate-based adhesive. Therefore, humidity in the environment in which the adhesive is used affects the adhesive hardening time. In order to accelerate the adhesive hardening time while preventing the variation of the adhesive hardening time caused by the difference in humidity in the environment where the adhesive is used, it is general thatA method of accelerating the hardening of the binder using a hardening accelerator is used.

Many instant adhesives are generally available on the market under the designation "cyanoacrylate 100%", but some of them contain a small amount of acidic substances added to cyanoacrylate-based adhesives to prevent the adhesives from hardening due to chain polymerization in the preserved state. In the case of using a general cyanoacrylate-based adhesive, it may take about one minute or only about one second, and the adhesive can be sufficiently hardened to obtain sufficient bonding strength, so that there is also a factor of variation in the precision of the material of the adhesive.

(hardening accelerator)

In the first exemplary embodiment, an example will be described in which a hardening accelerator for a cyanoacrylate-based adhesive is used as the hardening accelerator (i.e., a solvent containing a basic amine compound and acetone or alcohol as a solvent). Fig. 13 shows the chemical formula of a hardening accelerator for a cyanoacrylate-based adhesive. The hardening accelerator in the preserved state is present in a liquid state. The term "amine compound" is obtained by replacing ammonia (NH) with a hydrocarbon group or an aromatic radical₃) The hydrogen atom of (2) is a generic term for compounds derived from the hydrogen atom of (1). Although one hydrogen atom is replaced with a hydrocarbon group in the example shown in fig. 13, the number of hydrogen atoms to be replaced may be two or three. Amine compounds derived by replacement of one hydrogen atom are referred to as "primary amines". Amine compounds derived by replacing two hydrogen atoms are referred to as "secondary amines". Amine compounds derived by replacing three hydrogen atoms are referred to as "tertiary amines". The solvents (acetone, alcohol) of the hardeners containing the amine compounds are volatile.

As shown in fig. 13, when the hardening accelerator for a cyanoacrylate-based adhesive is applied, the solvent (acetone, alcohol) is evaporated within 2 seconds to 3 seconds, and the amine compound contained therein remains on the surface to which the hardening accelerator is applied. Then, the amine compound remaining on the surface and the cyanoacrylate-based adhesive are brought into contact with each other, thereby initiating a chain polymerization reaction, so that hardening of the adhesive is accelerated. The acceleration level of hardening of a cyanoacrylate-based adhesive by a hardening accelerator for the cyanoacrylate-based adhesive (specifically, the length of time before the cyanoacrylate-based adhesive is hardened) can be controlled by controlling the amount of the amine compound dissolved in a solvent of the hardening accelerator.

(bonding Process)

Next, details of a bonding step of bonding the doctor blade 36 according to the first exemplary embodiment will be described below with reference to a schematic diagram shown in fig. 14. In the first exemplary embodiment, as shown in fig. 14, a cyanoacrylate-based adhesive (hereinafter simply referred to as "adhesive 101") is applied to the blade attachment surface 41s of the developing frame 30. Further, a hardening accelerator as a volatile hardening accelerator (hereinafter also simply referred to as "hardening accelerator 102") for a cyanoacrylate-based adhesive is applied to the joining surface 36s of the doctor blade 36.

In the first exemplary embodiment, the ink scraping blade 36 is warped such that the SB gap G is within a predetermined range in the longer-side direction of the developing sleeve 70, and the ink scraping blade 36 in the warped state is fixed to the blade attachment portion 41 using the adhesive 101. At this time, in order to prevent the ink scraping blade 36 from returning from the warped state to the original state, it is necessary to bond the ink scraping blade 36 in the warped state to the entire maximum image area of the blade attachment portion 41. Therefore, in the first exemplary embodiment, the adhesive 101 is applied to the entire maximum image area of the blade attachment surface 41s of the developing frame 30, and the hardening accelerator 102 is applied to the entire maximum image area of the bonding surface 36s of the doctor blade 36.

As described above, the state in which the adhesive 101 is applied on the entire maximum image area of the blade attachment surface 41s of the developing frame 30 is a state in which the following condition is satisfied. Specifically, when the doctor blade 36 is attached to the blade attachment portion 41, the adhesive 101 is applied to 95% or more of the maximum image area of the blade attachment surface 41s of the developing frame 30 (including an area warped in a region corresponding to the maximum image area of the doctor blade 36 to correct the flatness of the coating quantity metering surface 36 r).

Similarly, the state in which the hardening accelerator 102 is applied to the entire maximum image area of the bonding surface 36s of the doctor blade 36 is a state in which the following condition is satisfied. Specifically, when the wiper blade 36 is attached to the blade attachment portion 41, the hardening accelerator 102 is applied to 95% or more of the maximum image area of the bonding surface 36s of the wiper blade 36 (including an area warped in a region corresponding to the maximum image area of the bonding surface 36s of the wiper blade 36 to correct the flatness of the coating tube control surface 36 r).

As described above, the solvent of the hardening accelerator 102 containing the amine compound is volatile, and after the solvent is volatilized within 2 seconds to 3 seconds, the amine compound remains on the surface to which the amine compound is applied, so that an effect of accelerating the hardening of the adhesive is produced. In other words, the hardening accelerator 102 is applied to the ink scraping blade 36, and after the solvent of the hardening accelerator 102 is volatilized, a force for warping the ink scraping blade 36 is applied to the ink scraping blade 36 in such a manner that the SB gap G is within a predetermined range in the longer side direction of the developing sleeve 70. Although the force for warping the ink scraping blade 36 is applied to the ink scraping blade 36 in this manner, the solvent of the hardening accelerator 102 applied to the ink scraping blade 36 is volatilized, so that the hardening accelerator 102 applied to the ink scraping blade 36 is less likely to drip from the ink scraping blade 36. Similarly, the hardening accelerator 102 is applied to the doctor blade 36, and after the solvent is volatilized, the orientation of the doctor blade 36 is changed so as to be attached to the blade attachment portion 41. Although the orientation of the ink-scraping blade 36 is changed as described above, the solvent applied to the hardening accelerator 102 of the ink-scraping blade 36 is volatilized, so that the hardening accelerator 102 applied to the ink-scraping blade 36 is less likely to drip from the ink-scraping blade 36.

Further, as described above, in the case of using a cyanoacrylate-based adhesive which is a commonly used adhesive, the length of time required for the adhesive to harden to obtain sufficient bonding strength varies from several seconds to about one minute. Longer setting time of the binder means lower productivity, and in order to increase productivity, it is necessary to use the hardening accelerator 102 to reduce the setting time of the binder. Therefore, the level of acceleration of the hardening of the adhesive 101 is controlled by controlling the amount of the amine compound contained in the hardening accelerator 102. In the first exemplary embodiment, the amount of the hardening accelerator 102 and the concentration of the amine compound to be applied to the bonding surface 36s of the doctor blade 36 are optimized to achieve an appropriate hardening time by adjusting the hardening using the hardening accelerator 102 so that the adhesive 101 is hardened in about five seconds.

A method of applying the adhesive 101 to the blade attachment surface 41s of the developing frame 30 and a method of applying the hardening accelerator 102 to the bonding surface 36s of the ink scraping blade 36 will be described below. Since the binder 101 and the hardening accelerator 102 are both liquid, the binder 101 and the hardening accelerator 102 are stored in different tanks, respectively.

The adhesive 101 stored in the tank is pumped, and a substantially fixed amount of the adhesive 101 is applied to the blade attachment surface 41s in the longer side direction of the blade attachment surface 41s by a dispenser equipped with a needle-like nozzle provided at the leading edge while the dispenser is moving. At this time, the moving speed of the dispenser is managed by the adhesive applying apparatus, and the dispenser is moved at a constant speed. In this way, the amount of adhesive 101 applied per unit area is stable.

Similarly, the hardening accelerator 102 stored in a different tank is pumped and a substantially fixed amount of the hardening accelerator 102 is applied to the bonding surface 36s of the ink-scraping blade 36 in the longer-side direction of the ink-scraping blade 36 by a dispenser equipped with a needle-like nozzle provided at the leading edge while the dispenser is moving. At this time, the moving speed of the dispenser is managed by the adhesive applying apparatus, and the dispenser is moved at a constant speed. In this manner, the amount of hardening accelerator 102 applied per unit area is stable.

As described above, in the first exemplary embodiment, the adhesive 101 is applied on the entire maximum image area of the blade attachment portion 41 of the developing frame 30. Further, the hardening accelerator 102 is applied over the entire maximum image area of the bonding surface 36s of the doctor blade 36.

Further, a force for warping the ink scraping blade 36 is applied to the ink scraping blade 36 in such a manner that the SB gap G is within a predetermined range in the longer side direction of the developing sleeve 70. At this time, the ink scraping blade 36 is warped by the force exerted on the ink scraping blade 36, and the SB gap G is in a predetermined range in the longer side direction of the developing sleeve 70. In this state, the doctor blade 36 applied with the hardening accelerator 102 is bonded to the blade attachment portion 41 applied with the adhesive 101. In this way, the SB gap G can be in a predetermined range in the longer side direction of the developing sleeve 70 while preventing variation in the curing time of the adhesive 101 when the resin doctor blade 36 extending in the longer side direction is bonded to the developing frame 30 made of resin.

Second exemplary embodiment

The second exemplary embodiment will be described below. In the first exemplary embodiment described above, an example is described in which the adhesive 101 is applied to the entire maximum image area of the blade attachment surface 41s of the developing frame 30, and the hardening accelerator 102 is applied to the entire maximum image area of the bonding surface 36s of the doctor blade 36. In the second exemplary embodiment, the hardening accelerator 102 is applied to the entire maximum image area of the blade attachment surface 41s of the developing frame 30, and the adhesive 101 is applied to the entire maximum image area of the bonding surface 36s of the doctor blade 36. Only the differences of the second exemplary embodiment from the first exemplary embodiment are described below, and descriptions similar to those in the first exemplary embodiment in the second exemplary embodiment are omitted. Details of a bonding step of bonding the doctor blade 36 according to the second exemplary embodiment will be described below with reference to a schematic diagram shown in fig. 15.

The state where the hardening accelerator 102 is applied over the entire maximum image area of the blade attachment surface 41s is a state where the following condition is satisfied. Specifically, when the doctor blade 36 is attached to the blade attachment portion 41, the hardening accelerator 102 is applied to 95% or more of the maximum image area of the blade attachment surface 41s (including the area warped in the area corresponding to the maximum image area of the doctor blade 36 to correct the flatness of the coating quantity metering surface 36 r).

Similarly, the state where the adhesive 101 is applied over the entire maximum image area of the bonding surface 36s of the doctor blade 36 is a state where the following condition is satisfied. Specifically, when the doctor blade 36 is attached to the blade attachment portion 41, the adhesive 101 is applied to 95% or more of the maximum image area of the bonding surface 36s of the doctor blade 36 (including an area warped in a region corresponding to the maximum image area of the doctor blade 36 to correct the flatness of the coating quantity metering surface 36 r).

The example according to the second exemplary embodiment is similar to the example according to the first exemplary embodiment in terms of an effect of preventing variation in the hardening time of the adhesive 101 when the resin doctor blade 36 extending in the longer-side direction is bonded to the developing frame 30 made of resin. However, since the developing device 3 is an industrial product to be mass-produced, the example according to the first exemplary embodiment is more desirable than the example according to the second exemplary embodiment from the viewpoint of productivity of mass production. The reason is as follows.

The process for manufacturing the developing device 3 includes sequentially assembling (combining) various components such as the developing sleeve 70, the doctor blade 36, and the cover frame 40 to the developing frame 30, which is a main component of the developing device 3, and thereby completing the developing device 3. Specifically, the orientation of the developing frame 30 is not substantially changed during the manufacturing process of the developing device 3. The change in the orientation of the developing frame 30 during the manufacturing process of the developing device 3 involves an operation of inverting or holding and rotating the developing frame 30 by an operator or a manufacturing device. These operations are generally to be avoided because the components attached to the developing frame 30 may be detached from the developing frame 30 due to gravity and centrifugal force.

Further, when it is necessary to change the orientation of a component, it is easy and common to change the orientation of a component which has a small volume and is light. Therefore, in the first exemplary embodiment described above, the orientation of the doctor blade 36, which has a smaller volume and is lighter than the developing frame 30, is changed, instead of changing the orientation of the developing frame 30, which is a main component of the developing device 3.

Returning to the description of the first exemplary embodiment, the orientation of the developing frame 30 and the doctor blade 36 when the adhesive 101 and the hardening accelerator 102 are applied according to the first exemplary embodiment will be described below with reference to the schematic view shown in fig. 16. Further, the orientation of the developing frame 30 and the ink blade 36 when the developing frame 30 and the ink blade 36 are combined will be described below with reference to a schematic diagram shown in fig. 17.

As shown in fig. 16, in a state where the developing frame 30 is placed substantially horizontally in the apparatus, the adhesive 101 is applied to the blade attachment surface 41s of the developing frame 30 by the adhesive applying apparatus. Similarly, as shown in fig. 16, the hardening accelerator 102 is applied to the bonding surface 36s of the ink scraping blade 36 by the hardening accelerator applying device in a state where the ink scraping blade 36 is placed substantially horizontally in the device.

In a state where the adhesive 101 (cyanoacrylate-based adhesive) is applied to the blade attachment surface 41s of the developing frame 30, the adhesive 101 maintains a dome-like cross-sectional shape (dome shape) due to viscosity and surface tension. However, if the developing frame 30 is shaken or tilted, the dome-like shape of the adhesive 101 may change due to the viscosity and the movability of the cyanoacrylate-based adhesive, and the adhesive 101 may drip from the blade attachment surface 41s by gravity. In other words, changing the orientation of the part to which the adhesive 101 is applied may cause the applied adhesive 101 to drip from the blade attachment surface 41 s.

Meanwhile, the hardening accelerator 102 (hardening accelerator for cyanoacrylate-based adhesives) is present in the form of a liquid. When the hardening accelerator 102 is applied, the solvent, which is acetone or alcohol, is volatilized within 2 seconds to 3 seconds, so that the amine compound 103 is held in a dry state on the bonding surface 36s of the doctor blade 36 to which the hardening accelerator 102 is applied. The amine compound 103 held in a dry state turns white, so that the operator can visually recognize the color changed to a whitish color. For verification, the ink scraping blade 36 was peeled off from the blade attaching portion 41 in a state where the bonding surface 36s of the ink scraping blade 36 and the blade attaching surface 41s of the developing frame 30 were bonded together. The bonded doctor blade 36 was peeled off from the blade attachment portion 41, and it was checked whether a color change to a whitish color (specifically, the color of the amine compound 103) was observable on the bonding surface 36s of the doctor blade 36 or on the blade attachment surface 41s of the developing frame 30. In this way, it is possible to check whether the adhesive 101 is applied to the bonding surface 36s of the ink blade 36 or the blade attachment surface 41s of the developing frame 30 and whether the hardening accelerator 102 is applied to the bonding surface 36s of the ink blade 36 or the blade attachment surface 41s of the developing frame 30.

As mentioned above, the hardening accelerator 102 (hardening accelerator for cyanoacrylate-based adhesives) is present in the form of a liquid. When the hardening accelerator 102 is applied, the solvent (i.e., acetone or alcohol) evaporates within two to three seconds. Thus, the orientation of the component to which the hardening accelerator 102 is applied can be easily changed even immediately after the hardening accelerator 102 is applied. As shown in fig. 17, after the solvent of the hardening accelerator 102 is volatilized, the orientation of the doctor blade 36 may be changed upside down by 180 degrees, or the doctor blade 36 may be moved in the direction of an arrow H in fig. 17 (from the upper side in the vertical direction toward the lower side in the vertical direction) so as to bond the doctor blade 36 to the blade attachment portion 41.

As described above, in the first exemplary embodiment, the ink scraping blade 36 having the bonding surface 36s to which the hardening accelerator 102 is applied is moved from the upper side in the vertical direction toward the lower side in the vertical direction. After that, the doctor blade 36 is attached to the blade attachment surface 41s of the developing frame 30 to which the adhesive 101 is applied. In this way, the doctor blade 36 is bonded to the blade attachment surface 41s of the developing frame 30 via the adhesive 101 and the hardening accelerator 102.

As described above in the first exemplary embodiment, the blade 36 applied with the hardening accelerator 102 is attached to the blade attachment surface 41s applied with the adhesive 101 of the developing frame 30, so that the blade 36 is bonded to the blade attachment surface 41s of the developing frame 30 via the adhesive 101 and the hardening accelerator 102.

Although the example shown in fig. 17 is described in which the position of the developing frame 30 having the blade attachment surface 41s to which the adhesive 101 is applied is fixed and the ink scraping blade 36 having the bonding surface 36s to which the hardening accelerator 102 is applied is moved from the upper side in the vertical direction toward the lower side in the vertical direction, the configuration is not limited to the above-described example.

In the modified example, the position of the doctor blade 36 having the bonding surface 36s to which the hardening accelerator 102 is applied is fixed, and the developing frame 30 having the blade attachment surface 41s to which the adhesive 101 is applied is moved from the lower side in the vertical direction toward the upper side in the vertical direction.

In another modified example, the position of the doctor blade 36 having the bonding surface 36s to which the hardening accelerator 102 is applied is moved from the upper side in the vertical direction toward the lower side in the vertical direction, and the developing frame 30 having the blade attachment surface 41s to which the adhesive 101 is applied is moved from the lower side in the vertical direction toward the upper side in the vertical direction.

Further, as described above, in the second exemplary embodiment, the ink scraping blade 36 applied with the adhesive 101 is attached to the blade attaching surface 41s applied with the hardening accelerator 102 of the developing frame 30, so that the ink scraping blade 36 is bonded to the blade attaching surface 41s of the developing frame 30 via the adhesive 101 and the hardening accelerator 102.

For example, the position of the doctor blade 36 having the bonding surface 36s to which the adhesive 101 is applied is fixed, and the developing frame 30 having the blade attachment surface 41s to which the hardening accelerator 102 is applied is moved from the upper side in the vertical direction toward the lower side in the vertical direction.

In the modified example, the position of the developing frame 30 having the blade attachment surface 41s to which the hardening accelerator 102 is applied is fixed, while the ink scraping blade 36 having the bonding surface 36s to which the adhesive 101 is applied is moved from the lower side in the vertical direction toward the upper side in the vertical direction.

In another modified example, the developing frame 30 having the blade attachment surface 41s to which the hardening accelerator 102 is applied is moved from the upper side in the vertical direction toward the lower side in the vertical direction, and the doctor blade 36 having the bonding surface 36s to which the adhesive 101 is applied is moved from the lower side in the vertical direction toward the upper side in the vertical direction.

(other exemplary embodiments)

The above-described exemplary embodiments are not intended to limit the scope of the claimed disclosure, and various modifications (including various combinations of the exemplary embodiments) may be made based on the spirit of the present disclosure, and these modifications are not excluded from the scope of the claimed disclosure.

Although the image forming apparatus 60 using the ITB 61 as the intermediate transfer member as shown in fig. 1 is described as an example in the above-described exemplary embodiment, the structure is not limited to the above-described structure. The present disclosure can also be applied to an image forming apparatus configured to sequentially bring a recording material into direct contact with the photosensitive drum 1 to perform a transfer process.

Further, although the developing device 3 is described as a single unit in the above-described exemplary embodiment, the image forming unit 600 (refer to fig. 1) including the developing device 3 may be integrated into the unit in the form of a process cartridge that is removable from the image forming device 60 and attachable to the image forming device 60. The process cartridge can also produce similar advantages. Further, the present disclosure is applicable to any image forming apparatus 60 including the developing apparatus 3 or the process cartridge, regardless of whether the image forming apparatus 60 is a monochrome image forming apparatus or a color image forming apparatus.

While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. A method of attaching a regulating blade to an attachment portion of a developing frame made of resin and including the attachment portion for attaching the regulating blade, the regulating blade being disposed opposite to and not in contact with a developing rotary member configured to carry and convey a developer toward a position where an electrostatic latent image formed on an image bearing member is developed, the regulating blade being configured to regulate an amount of the developer carried on the developing rotary member, the method of attaching the regulating blade comprising:

a first application step of applying an adhesive to the attachment portion;

a second application step of applying a hardening accelerator to the regulating blade; and

an attaching step of attaching the regulating blade to the attaching portion via the adhesive applied to the attaching portion in the first applying step and the hardening accelerator applied to the regulating blade in the second applying step.

2. The method of attaching the regulating blade of claim 1, further comprising:

a moving step of moving the regulating blade to which the hardening accelerator is applied in the second applying step from an upper side to a lower side in a vertical direction,

wherein in the attaching step, the regulating blade that is moved from an upper side to a lower side in the vertical direction in the moving step is attached to the attaching portion via the adhesive applied to the attaching portion in the first applying step and the hardening accelerator applied to the regulating blade in the second applying step.

3. The method of attaching the regulating blade of claim 1, further comprising:

a moving step of moving the attachment portion to which the adhesive is applied in the first applying step from a lower side to an upper side in a vertical direction,

wherein in the attaching step, the regulating blade is attached to the attaching portion that moves from a lower side to an upper side in the vertical direction via the adhesive applied to the attaching portion in the first applying step and the hardening accelerator applied to the regulating blade in the second applying step.

4. The method of attaching the regulating blade of claim 1, further comprising:

a first moving step of moving the attachment portion to which the adhesive is applied in the first applying step from a lower side to an upper side in a vertical direction; and

a second moving step of moving the regulating blade to which the hardening accelerator is applied in the second applying step from an upper side to a lower side in the vertical direction,

wherein, in the attaching step, the regulating blade that is moved from an upper side to a lower side in the vertical direction in the second moving step is attached to the attaching portion that is moved from a lower side to an upper side in the vertical direction in the first moving step via the adhesive applied to the attaching portion in the first applying step and the hardening accelerator applied to the regulating blade in the second applying step.

5. The method of attaching the regulating blade of claim 1 or 2, further comprising:

a force applying step of applying a force for warping the regulating blade on the regulating blade,

wherein in the attaching step, the regulating blade is attached to the attaching portion in a state where the regulating blade is kept warped by the force applied to the regulating blade in the force applying step.

6. The method of attaching the regulating blade according to claim 5, wherein in the force application step, a force for warping the regulating blade is applied to the regulating blade to which the hardening accelerator is applied in the second application step.

7. The method of attaching the regulating blade according to claim 1 or 2, wherein in the first applying step, the adhesive is applied to the attachment portion over substantially an entire area of the attachment portion corresponding to a maximum image area of the image bearing member at which an image can be formed on the image bearing member.

8. The method of attaching the regulating blade according to claim 1 or 2, wherein in the second applying step, the hardening accelerator is applied to the regulating blade over substantially an entire area of the regulating blade corresponding to a maximum image area of the image bearing member at which an image can be formed on the image bearing member.

9. A method of attaching a regulating blade to an attachment portion of a developing frame made of resin and including the attachment portion for attaching the regulating blade, the regulating blade being disposed opposite to and not in contact with a developing rotary member configured to carry and convey a developer toward a position where an electrostatic latent image formed on an image bearing member is developed, the regulating blade being configured to regulate an amount of the developer carried on the developing rotary member, the method of attaching the regulating blade comprising:

a first application step of applying an adhesive to the regulating blade;

a second application step of applying a hardening accelerator to the attachment portion; and

an attaching step of attaching the regulating blade to the attaching portion via the adhesive applied to the regulating blade in the first applying step and the hardening accelerator applied to the attaching portion in the second applying step.

10. The method of attaching the regulating blade of claim 9, further comprising:

a moving step of moving the attachment portion to which the hardening accelerator is applied in the second applying step from an upper side to a lower side in a vertical direction,

wherein in the attaching step, the regulating blade is attached to the attaching portion that moves from an upper side to a lower side in the vertical direction in the moving step via the adhesive applied to the regulating blade in the first applying step and the hardening accelerator applied to the attaching portion in the second applying step.

11. The method of attaching the regulating blade of claim 9, further comprising:

a moving step of moving the regulating blade to which the adhesive is applied in the first applying step from a lower side to an upper side in a vertical direction,

wherein in the attaching step, the regulating blade that is moved from a lower side to an upper side in the vertical direction in the moving step is attached to the attaching portion via the adhesive applied to the regulating blade in the first applying step and the hardening accelerator applied to the attaching portion in the second applying step.

12. The method of attaching the regulating blade of claim 9, further comprising:

a first moving step of moving the regulating blade to which the adhesive is applied in the first applying step from a lower side to an upper side in a vertical direction,

a second moving step of moving the attachment portion to which the hardening accelerator is applied in the second applying step from an upper side to a lower side in the vertical direction,

wherein, in the attaching step, the regulating blade that is moved from a lower side to an upper side in the vertical direction in the first moving step is attached to the attaching portion that is moved from an upper side to a lower side in the vertical direction in the second moving step via the adhesive applied to the regulating blade in the first applying step and the hardening accelerator applied to the attaching portion in the second applying step.

13. The method of attaching the regulating blade of claim 9 or 10, further comprising:

14. The method of attaching the regulating blade according to claim 13, wherein in the force application step, a force for warping the regulating blade is applied to the regulating blade to which the adhesive is applied in the first application step.

15. The method of attaching the regulating blade according to claim 9 or 10, wherein in the first applying step, the adhesive is applied to the regulating blade over substantially an entire area of the regulating blade corresponding to a maximum image area of the image bearing member at which an image can be formed on the image bearing member.

16. The method of attaching the regulating blade according to claim 9 or 10, wherein in the second applying step, the hardening accelerator is applied to the attaching portion over substantially an entire area of the attaching portion corresponding to a maximum image area of the image bearing member where an image can be formed on the image bearing member.

17. A developing apparatus, comprising:

a developing rotary member configured to carry a developer and convey the developer toward a position where an electrostatic latent image formed on an image bearing member is developed;

a regulating blade made of resin, disposed opposite to the developing rotary member, and not in contact with the developing rotary member, the regulating blade being configured to regulate an amount of the developer carried on the developing rotary member; and

a developing frame made of resin and including an attaching portion for attaching the regulating blade,

wherein the regulating blade is bonded to the attachment portion via an adhesive and a hardening accelerator.

18. A developing apparatus according to claim 17, wherein the regulating blade is bonded to the attachment portion over substantially an entire area of the regulating blade corresponding to a maximum image area of the image bearing member at which an image can be formed on the image bearing member.

19. A developing device according to claim 17 or 18, wherein said regulating blade is bonded to said attachment portion via said adhesive agent provided to said attachment portion and said hardening accelerator provided to said regulating blade.

20. The developing device according to claim 17 or 18, wherein the regulating blade is bonded to the attaching portion via the adhesive provided to the regulating blade and the hardening accelerator provided to the attaching portion.