US20110203902A1

US20110203902A1 - Sheet feeding/separation apparatus and recording apparatus

Info

Publication number: US20110203902A1
Application number: US13/033,487
Authority: US
Inventors: Masayoshi Sakuyama
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 2010-02-24
Filing date: 2011-02-23
Publication date: 2011-08-25
Also published as: JP5578878B2; JP2011173693A

Abstract

A feeding/separation apparatus includes a feeding mechanism configured to feed a recording medium stacked on a sheet feeding unit, and a separation mechanism having a feeding member driven in a sheet feeding direction and a separation member driven in a direction opposite to the sheet feeding direction, a drawing member driven in the sheet feeding direction is disposed downstream of a nip portion formed by the separation member, and wherein the distance between the nip portion by the drawing member and the nip portion by the separation member in the sheet feeding direction is x/2 or less, where x denotes a minimum length of the recording medium.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a sheet feeding/separation apparatus and a recording apparatus which uses the sheet feeding/separation apparatus.
2. Description of the Related Art
Some of printers, facsimile apparatuses, copying machines, and other recording apparatuses have a sheet feeding/separation apparatus including a feeding mechanism for feeding a recording medium stacked on a sheet feeding unit and a separation mechanism for separating the fed recording medium and sending it into a conveyance unit. With a thus-configured sheet feeding/separation apparatus, a difference in friction coefficient between separation members, sheet feeding members, and a recording medium is utilized when feeding and separating envelopes as a recording medium. With this method, since the separation members may apply a frictional force in a direction opposite to the sheet feeding direction, the upper and lower surfaces of the envelope are displaced and the envelope bends, possibly resulting in paper jam.
Japanese Patent Application Laid-Open No. 05-024664 discusses a sheet feeding apparatus based on another sheet feeding method. Specifically, pressing members disposed upstream of a feed roller in the sheet feeding direction convexly deform an envelope stacked in a cassette and, at the same time, a pickup roller presses the envelope's leading end having a high stiffness. The thus-configured sheet feeding apparatus increases the apparent stiffness of the envelope to restrain a displacement between the upper and lower surfaces of the envelope, thus preventing paper jam.
However, with the above-mentioned conventional method, a long distance from a reverse roller (separation member) to a conveyance roller disposed downstream thereof may cause paper jam. Specifically, when a low-stiffness portion (middle portion) of the envelope being conveyed reaches the reverse roller, a displacement occurs between the upper and lower surfaces of the envelope and it bends, possibly resulting in paper jam.

SUMMARY OF THE INVENTION

The present invention is directed to a feeding separation apparatus and a recording apparatus capable of preventing, when feeding and separating an envelope as a recording medium, paper jam caused by a displacement between the upper and lower surfaces of the envelope.
According to an aspect of the present invention, a feeding/separation apparatus includes a feeding mechanism configured to feed a recording medium stacked on a sheet feeding unit, and a separation mechanism having a feeding member driven in a sheet feeding direction and a separation member driven in a direction opposite to the sheet feeding direction, a drawing member driven in the sheet feeding direction is disposed downstream of a nip portion formed by the separation member, and wherein the distance between the nip portion by the drawing member and the nip portion by the separation member in the sheet feeding direction is x/2 or less, where x denotes a minimum length of the recording medium.
Further features and aspects of the present invention will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments, features, and aspects of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1 is a side view illustrating a recording apparatus having a sheet feeding/separation apparatus according to a first exemplary embodiment.

FIG. 2 illustrates the orientation of a flap on the lower surface of an envelope with respect to the sheet feeding direction.

FIG. 3 is a perspective view illustrating the sheet feeding/separation apparatus according to the first exemplary embodiment.

FIG. 4 is an elevational view illustrating nip portions formed by drawing rollers.

FIG. 5 is a plan view illustrating separation belts and drawing rollers.

FIG. 6 is a block diagram illustrating a control system of the recording apparatus.

FIG. 7 is a flow chart illustrating a feeding start operation by the sheet feeding/separation apparatus.

FIG. 8 is a graph illustrating a relation between an appropriate position of the drawing rollers, the stiffness of the envelope, and the frictional force of the separation belts.

FIG. 9 is a side view illustrating a bend of the envelope caused by the separation belts.

FIG. 10 is a graph illustrating a relation between the position of the drawing rollers and the amount of bend of the envelope.

FIG. 11 is tables illustrating the characteristics of the separation belts and the drawing rollers for comparison.

FIG. 12 is a side view illustrating a sheet feeding/separation apparatus according to a second exemplary embodiment.

FIG. 13 is a side view illustrating a sheet feeding/separation apparatus according to a third exemplary embodiment.

DESCRIPTION OF THE EMBODIMENTS

Various exemplary embodiments, features, and aspects of the invention will be described in detail below with reference to the drawings. In the accompanying drawings, the same reference numerals denote identical or equivalent parts.
FIG. 1 is a side view illustrating a recording apparatus having a sheet feeding/separation apparatus 100A. FIG. 2 illustrates the orientation of a flap 41 on the lower surface of an envelope 3 with respect to the sheet feeding direction. FIG. 3 is a perspective view illustrating the sheet feeding/separation apparatus 100A according to a first exemplary embodiment.
The feeding/separation apparatus 100A includes a feeding mechanism 50 disposed on the upstream side of the conveyance path, and a separation mechanism 70A disposed downstream of the feeding mechanism 50. The feeding mechanism 50 feeds envelopes 3 stacked on a sheet feeding unit 51 one by one to the separation mechanism 70A.
As illustrated in FIGS. 2 and 3, a bundle of envelopes 3 is stacked on the sheet feeding unit 51 of the feeding mechanism 50, with an opening portion of the flap 41 of the envelope 3 turned down perpendicularly to the sheet feeding direction. Each envelope 3 can be conveyed with a folding edge 42 of the flap 41 aligned on the side of a conveyance reference plane 52 during feeding.
The envelopes 3 stacked on the sheet feeding unit 51 are fed one by one onto feeding belts 2 of the separation mechanism 70A by feed roller pairs 55 disposed on the sheet feeding unit 51.
The separation mechanism 70A includes separation belts 1 (separation members) driven by a DC motor (not illustrated), the feeding belts 2 (feeding members), and drawing rollers 4 (drawing members). The feeding belts 2 driven in the sheet feeding direction are disposed under the conveyance path and fixed by two shafts. The separation belts 1 driven in a direction opposite to the sheet feeding direction are disposed above the feeding belts 2 (above the conveyance path).
The upstream-side ends of the separation belts 1 are fixed by a shaft. The downstream portions of the separation belts 1 overlap the leading ends of the feeding belts 2 so that the separation belts 1 are inclined to enable nip portions to be formed. The separation belts 1 are rotatable centering on the fixing shaft, and movable in both directions denoted by arrows in FIG. 1 (opening and closing movement) so as to open and close the nip portions by the feeding belts 2. The opening and closing movement of the separation belts 1 enable conveyance of both thin and thick paper sheets.
Each separation belt 1 and each feeding belt 2 relatively come closer to each other on the more downstream side in the sheet feeding direction, and overlap each other at their downstream-side ends. In this overlap area, as illustrated in FIGS. 1 and 3, a plurality of separation belts 1 arranged like comb teeth and a plurality of feeding belts 2 arranged like comb teeth are interleaved to form a separation portion 6. The leading end of each separation belt 1 is biased by a spring (not illustrated) to give a nip pressure to the separation portion 6.
FIG. 4 is an elevational view illustrating nip portions formed by the drawing rollers 4 and a platen 7 when viewed from the upstream side in the sheet feeding direction. FIG. 5 is a plan view illustrating arrangements of the separation belts 1 and the drawing rollers 4.
The drawing rollers 4 are disposed above the conveyance path, downstream of the separation portion 6 in the sheet feeding direction. The platen 7 is disposed under the conveyance path, downstream of the separation portion 6 in the sheet feeding direction. The platen 7 is provided with concave portions 53. The drawing rollers 4 overlap the concave portions 53 to form nip portions.
With the sheet feeding/separation apparatus 100A, as illustrated in FIGS. 2 to 4, the separation belts 1 include a plurality of (four) separation belts 1 a, 1 b, 1 c, and 1 d, the feeding belts 2 include a plurality of (four) feeding belts 2 a, 2 b, 2 c, and 2 d, and the drawing rollers 4 include a plurality of (four) drawing rollers 4 a, 4 b, 4 c, and 4 d. The drawing rollers 4 a, 4 b, 4 c, and 4 d are disposed at extended portions of the separation belts 1 a, 1 b, 1 c, and 1 d, respectively, in the sheet feeding direction.
Referring to FIG. 4, the concave portions 53 include a plurality of (four) concave portions 53 a, 53 b, 53 c, and 53 d corresponding to the drawing rollers 4 a, 4 b, 4 c, and 4 d, respectively. The above-mentioned feeding mechanism 50A and separation mechanism 70A are driven by a motor which is also the drive source of the drawing rollers 4.
FIG. 6 is a block diagram of a control system of the recording apparatus. FIG. 7 is a flow chart illustrating a feeding start operation by the sheet feeding/separation apparatus 100.
A motor 25 drives the separation belts 1 (separation members), the feeding belts 2 (feeding members), and the drawing rollers 4 (drawing members). The feeding belts 2 and the drawing rollers 4 are driven constantly in the sheet feeding direction during sheet feeding. The separation belts 1 are driven constantly to a direction opposite to the sheet feeding direction even after an envelope is separated from the bundle.
In step S1, a control apparatus 21 determines the presence of an envelope based on information input from an envelope presence sensor 22. When the control apparatus 21 determines the presence of an envelope (YES in step S1), the processing proceeds to step S2. In step S2, the motor 25 drives the separation belts 1, the feeding belts 2, and the drawing rollers 4.
In step S3, based on information from a jam sensor 23, the control apparatus 21 determines the presence of paper jam from a blank time between papers while an envelope is being fed. When the control apparatus 21 determines that paper jam is not present (NO in step S3), the processing proceeds to step S4. In step S4, the control apparatus 21 drives the separation belts 1, the feeding belts 2, and the drawing rollers 4 by using the motor 25.
Referring to FIG. 6, the control apparatus 21 includes a central processing unit CPU 31 connected to a read-only memory (ROM), an electrically erasable programmable ROM (EEPROM), and a random access memory (RAM) storing various programs and various data. The control apparatus 21 is connected to a host apparatus such as a personal computer via a host interfaces such as a USB interface, a network, etc.
Referring to FIG. 1, a recording unit 20 for performing recording on a recording medium (envelope) 3 using recording heads 29 based on image information is provided above the platen 7 (above the conveyance path).
In the recording unit 20, the recording heads 29 are mounted on a carriage 82 that can make a reciprocating motion (main scan) along a guide shaft 81 disposed in the width direction of the recording apparatus. The recording heads 29 are ink jet recording heads which discharge ink from nozzles based on image information to perform recording.
The recording heads 29 include a plurality of (four) recording heads 29 a, 29 b, 29 c, and 29 d using ink of a plurality of (four) colors for performing color recording.
The envelope 3 is fed onto the platen 7 via the nip portions (separation portion) 6 formed by the separation belts 1 and the feeding belts 2, and the nip portions formed by the drawing rollers 4 and the concave portions 53 of the platen 7 (FIG. 4). The envelope 3 is further conveyed by a conveyance roller pair 5 disposed downstream of the platen 7.
The recording heads 29 perform image formation (recording) onto the envelope 3 conveyed onto the platen 7 by the conveyance roller pair 5. The recording medium (envelope) 3 that has undergone image formation is further conveyed by the conveyance roller pair 5, and then discharged onto a discharge tray 83 provided outside the recording apparatus.
The nip portions for nipping the recording medium 3 are formed between the drawing rollers 4 and the concave portions 53 of the platen 7, as illustrated in FIG. 4. Referring to FIG. 1, the nip portions by the separation belts 1 are disposed downstream of the separation portion 6 (nip portions by the drawing rollers 4) at a distance of x/2 or less therefrom, where x denotes the length of the recording medium 3 in the sheet feeding direction having a minimum length determined for the recording apparatus. The length x in this case may be the minimum length of the recording medium 3 to be used.
The drawing rollers 4 are disposed above the platen 7 and above the conveyance path of the recording medium 3, and driven in the sheet feeding direction by the DC motor commonly used for the feeding mechanism 50 and the separation mechanism 70A. The drawing rollers 4 are disposed on the same side as the separation belts 1 in terms of the upper and lower surfaces of the envelope 3 (above the conveyance path in FIG. 1), and driven in the sheet feeding direction.
With the recording apparatus in FIG. 1, conveyance members (conveyance rollers) 5 for conveying the recording medium (envelope) 3 in the sheet feeding direction are disposed downstream of the separation belts 1, and the drawing rollers 4 are disposed between the nip portions (separation portion) 6 by the separation belts 1 and nip portions by the conveyance members 5.
FIG. 8 is a graph illustrating a relation between an appropriate position of the drawing rollers 4, the stiffness of the envelope 3, and the frictional force of the separation belts 1. FIG. 9 is a side view illustrating a bend of the envelope 3 by the separation belts 1. FIG. 10 is a graph illustrating a relation between the position of the drawing rollers 4 and the amount of bend of the envelope 3. FIG. 11 illustrates tables of the characteristics of the separation belts 1 and the drawing rollers 4 for comparison.
Although the envelope 3 may be fed with the flap 41 pasted, a case is described below where the envelope 3 is fed without pasting the flap 41 where the stiffness is low, and feeding and separation are difficult.
FIG. 8 illustrates that the bend of the envelope 3 does not occur under a condition of b>a, where a denotes the frictional force generated by the separation belts 1 to upwardly bend the upper surface of the envelope 3, and b denotes the resistance of the envelope 3 to the bend, which decreases as a middle portion of the envelope 3 being conveyed comes closer to the separation portion 6.
Referring to FIG. 8, the condition b>a is satisfied when the distance from the leading edge of the envelope 3 to the separation portion 6 downstream of the envelope 3 is 32 mm or less. Accordingly, disposing the drawing rollers 4 in this range makes it possible to nip the envelope 3 at the nip portions by the drawing rollers 4 and the concave portions 53 of the platen 7 before a low-stiffness portion of the envelope 3 being conveyed reaches the separation portion 6, thus preventing the bend of the envelope 3.
The bend of the envelope 3 occurs because conveyance forces in opposite directions are applied to the separation side on the upper surface of the envelope 3 and the feeding side on the lower surface thereof, as illustrated in FIG. 9. In other words, the bend of the envelope 3 is caused by a displacement between its upper and lower surfaces.
FIG. 9 illustrates the envelope 3 bending upwardly when it is fed by the separation mechanism 70A according to the first exemplary embodiment, i.e., it bends upwardly toward the separation side.
On the other hand, when the separation side (separation belts 1) is provided under the conveyance path, and the feeding side (feeding belts 2) is provided above the conveyance path, the envelope 3 bends in a direction opposite to the bending direction in FIG. 9, i.e., it bends downwardly toward the separation side.
FIG. 10 is a graph illustrating a relation between the amount of bend (mm) of the envelope 3 and the distance (mm) from the nip portions by the separation portion 6 to the nip portions by the drawing rollers 4. FIG. 10 also illustrates the characteristics of the amount of bend of the envelope 3 when the drawing rollers 4 are disposed downstream of the separation portion 6 at a distance exceeding 32 mm therefrom i.e., when the envelope 3 is nipped by the nip portions by the drawing rollers 4 after the leading edge of the envelope 3 has been fed to a position downstream of the separation portion 6 at a distance exceeding 32 mm therefrom.
FIG. 10 illustrates that, when the distance from the separation portion 6 to the drawing rollers is x/2 or less, where x denotes the length of the recording medium having the determined minimum length, or the minimum length of the recording medium used), the amount of bend of the envelope 3 can be maintained to 10 mm or less. In this case, to prevent paper jam occurring when the envelope 3 enters the drawing rollers 4, the radius of the drawing rollers 4 is preferably set to 15 mm or more.
As illustrated in tables in FIG. 11, almost the same pressure (load) as the one applied to the separation belts 1 is also applied to the drawing rollers 4. The drawing rollers 4 are made of a material having a higher friction coefficient μ than that of the separation belts 1. Therefore, the frictional force produced between the drawing rollers 4 and the envelope 3 is larger than the frictional force produced between the separation belts 1 and the envelope 3.
The diameter of the drawing rollers 4 is almost the same as twice the curvature radius of the end of the separation belts 1 (corresponding to the diameter of the rollers). However, since the conveyance speed (feeding speed) of the drawing rollers 4 is larger than the conveyance speed of the separation belts 1, the conveyance amount of the drawing rollers 4 is larger than the conveyance amount of the separation belts 1. Specifically, the drawing rollers 4 generate a higher frictional force and a larger conveyance amount than the separation belts 1 do.
When the relation illustrated in FIG. 11 is satisfied, the drawing rollers 4 are set to a position 32 mm or more downstream of the separation portion 6. In this case, even when the upper surface of the envelope 3 is slightly bent by the drive of the separation belts 1, the envelope 3 can be further conveyed while the bend being pulled back in the sheet feeding direction.
Thus, the drawing members (drawing rollers) 4 driven in the sheet feeding direction enable nipping the envelope 3 before a low-stiffness portion of the envelope 3 reaches the nip portions (separation portion) 6 by the separation members (separation belts) 1, and a displacement between the upper and lower surfaces of the envelope 3 bends the envelope 3.
At the same time, when a displacement occurs between the upper and lower surfaces of the envelope 3, the displacement is pulled back in the sheet feeding direction. The above-mentioned configuration enables the drawing members 4 to nip the envelope 3 before a low-stiffness portion of the envelope 3 being conveyed in the sheet feeding direction reaches the separation portion 6, thus preventing the envelope 3 from being bent by a displacement between its upper and lower surfaces.
At the same time, the drawing members 4 driven in the sheet feeding direction enable pulling back the displacement on the upper or lower surface of the envelope 3 in the sheet feeding direction. Preventing in this way the envelope 3 from being bent by a displacement between its upper and lower surfaces can prevent paper jam.
FIG. 12 is a side view illustrating a separation portion 72 of a separation mechanism 70B in a sheet feeding/separation apparatus 100B according to a second exemplary embodiment. The present exemplary embodiment differs from the first exemplary embodiment in that separation rollers 8 are used instead of the separation belts 1 and drawing rollers 9 driven via the separation rollers 8 are used instead of the drawing rollers 4. Also in FIG. 12, parts identical or equivalent to those in the first exemplary embodiment are assigned the same reference numerals.
Referring to FIG. 12, the separation rollers 8 (separation members) are pressed onto drive rollers 71 for the feeding belts 2 via the feeding belts 2 from above the conveyance path to form the separation portion 72 including nip portions. The separation rollers 8 and the drawing rollers 9 disposed downstream of the separation rollers 8 in the sheet feeding direction are provided as a unit. Concentric gears 10 a provided on the side faces of the separation rollers 8 are engaged with concentric gears 10 b provided on the side faces of the drawing rollers 9.
When the motor 25 (FIG. 6), a drive source, drives the separation rollers 8 to a direction opposite to the sheet feeding direction, the drawing rollers 9 are driven in the sheet feeding direction in synchronization with the separation rollers 8. The separation portion 72 formed by nip portions by the separation rollers 8 and the feeding belts 2 corresponds to the separation portion 6 in the first exemplary embodiment. Other configurations and operations of the present exemplary embodiment are similar to those in the first exemplary embodiment.
The present exemplary embodiment enables obtaining similar functions and effects to those in the first exemplary embodiment by disposing the drawing rollers 9 close to the separation portion 72. Specifically, the above-mentioned configuration enables the drawing members 9 to nip the envelope 3 before a low-stiffness portion of the envelope 3 being conveyed in the sheet feeding direction reaches the separation portion 72, thus preventing the envelope 3 from being bent by a displacement between its upper and lower surfaces.
At the same time, the drawing members 9 driven in the sheet feeding direction enable pulling back the displacement on the upper or lower surface of the envelope 3 in the sheet feeding direction. Preventing in this way the envelope 3 from being bent by a displacement between its upper and lower surfaces can prevent paper jam.
FIG. 13 is a side view illustrating a sheet feeding/separation apparatus 100C according to a third exemplary embodiment. The feeding/separation apparatus 100C includes a feeding mechanism 50C and a separation mechanism 70C. With the feeding mechanism 70C, a bundle of envelopes 3 is stacked on a sheet feeding unit cassette 15, with an opening portion of the flap 41 turned up perpendicularly to the sheet feeding direction. Each envelope 3 can be conveyed with a folding edge of the flap 41 aligned on the side of a conveyance reference plane (not illustrated) which is equivalent to the conveyance reference plane 52 in FIG. 3.
The envelopes 3 on the sheet feeding unit cassette 15 are fed one by one from the top downward by built-in pickup rollers 13. A separation portion 14 is provided downstream of the feeding mechanism 70C. Feed rollers 12 (feeding members) are pressed onto a separation pad 11 (separation member) at the separation portion 14. The separation pad 11 is disposed below the conveyance path, and the feed rollers 12 are disposed above the conveyance path.
In the example in FIG. 13, the separation pad 11 is pressed from an oblique direction with respect to the feed rollers 12. The separation pad 11 is made of a material having a comparatively large friction coefficient. Nip portions of the separation portion 14 are formed at press-contact portions between the feed rollers 12 and the separation pad 11. These nip portions separate an uppermost envelope 3.
Drawing roller pairs composed of drawing rollers 73 and driven rollers 17 are disposed downstream of the separation portion 14 at a distance of x/2 or less therefrom, where, similar to the first exemplary embodiment, x denotes a minimum length of the recording medium determined for the recording apparatus or the minimum length of the recording medium to be used.
In this case, the drawing rollers 73 driven in the sheet feeding direction are disposed below the conveyance path, on which side the separation pad 11 is located, and the driven rollers 17 are disposed above the conveyance path, on which side the feed rollers 12 are located. The drawing rollers 73 are made of a material having almost the same friction coefficient p as the material of the separation pad 11.
A nip pressure (pressing force) higher than the nip pressure applied to the separation portion 14 is applied to the nip portions by the drawing roller pairs (pairs of drawing rollers 73 and 17). The drawing rollers 73 are rotated at a speed higher than the feed rollers 12 to provide a conveyance amount larger than the conveyance amount at the separation portion 14. Conveyance rollers 16 for conveying the recording medium (envelope) 3 via an image forming portion facing recording heads 29 are disposed downstream of the drawing roller pairs (pairs of drawing rollers 73 and 17).
With the above-mentioned configuration, even when the lower surface of the envelope 3 is slightly bent on the separation pad 11 at the separation portion 14, the envelope 3 can be further conveyed while pulling back the bend in the sheet feeding direction by using the drawing rollers 73. Therefore, the present exemplary embodiment enables obtaining similar functions and effects to those in the first exemplary embodiment by disposing the drawing rollers 73 close to the separation portion 14.
Specifically, the above-mentioned configuration enables the drawing members 73 to nip the envelope 3 before a low-stiffness portion of the envelope 3 being conveyed in the sheet feeding direction reaches the separation portion 14, thus preventing the envelope 3 from being bent by a displacement between its upper and lower surfaces. At the same time, the drawing members 73 driven in the sheet feeding direction enable pulling back the displacement on the upper or lower surface of the envelope 3 in the sheet feeding direction. Preventing in this way the envelope 3 from being bent by a displacement between its upper and lower surfaces can prevent paper jam.
A fourth exemplary embodiment has drawing belts instead of the drawing rollers 4 in the first exemplary embodiment. Specifically, the drawing belts driven in the sheet feeding direction are used as drawing members.
The drawing belts are disposed downstream of the separation portion 6 so that their upstream-side ends are at a distance of x/2 or less therefrom. The drawing belts are disposed above the conveyance path, on which side the separation belts 1 are located. Since the drawing belts can be configured to convey a recording medium through a position facing the recording heads 29, they can be also used as conveyance members for conveying the recording medium in the sheet feeding direction.
A relation between the separation belts 1 and the drawing belts in terms of the rotational direction, frictional force, and the conveyance amount is similar to the relation between the separation belts 1 and the drawing rollers 4 in the first exemplary embodiment illustrated in FIG. 11. Other configurations of the present exemplary embodiment are similar to those in the first exemplary embodiment. The above-mentioned configuration also enables obtaining similar functions and effects to those in the first exemplary embodiment.
The present invention is not limited to the above-mentioned exemplary embodiments. In addition to using, for example, the drawing rollers 4, 9, and 73 and drawing belts as drawing members, other methods such as a sliding mechanism can be used as long as an envelope can be conveyed in the sheet feeding direction.
The separation portions 6, 72, and 14 disposed upstream of the drawing rollers 4 may be configured in diverse ways other than the above on the premise that a recording medium is separated by utilizing a difference in frictional force.
Although the above exemplary embodiments have specifically been described based on an ink jet recording apparatus which performs recording by discharging ink from recording heads, the present invention is also applicable to recording apparatuses of thermal transfer, laser beam, heating, wire dot, and other types.
The present invention is also applicable to any scanning method such as the serial method with which recording is made by alternately repeating main scan by recording heads and subscan by conveyance operation, and the line method with which recording is continuously made only through subscan by conveyance operation.
The present invention is also applicable to any number of recording heads, any ink types, and any number of ink aspects. The present invention is also applicable to recording media (envelopes and sheets) made of different materials such as paper, plastic film, printing paper, nonwoven fabric, and so on.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention 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 modifications, equivalent structures, and functions.
This application claims priority from Japanese Patent Application No. 2010-039385 filed Feb. 24, 2010, which is hereby incorporated by reference herein in its entirety.

Claims

1. A feeding/separation apparatus comprising:

a feeding mechanism configured to feed a recording medium stacked on a sheet feeding unit; and

a separation mechanism having a feeding member driven in a sheet feeding direction and a separation member driven in a direction opposite to the sheet feeding direction,

a drawing member driven in the sheet feeding direction is disposed downstream of a nip portion formed by the separation member, and

wherein the distance between the nip portion by the drawing member and the nip portion by the separation member in the sheet feeding direction is x/2 or less, where x denotes a minimum length of the recording medium.

2. The feeding/separation apparatus according to claim 1, wherein the recording medium is an envelope.

3. The feeding/separation apparatus according to claim 2, wherein the drawing member is a drawing roller, drawing belt, or drawing slider for conveying the envelope in the sheet feeding direction.

4. The feeding/separation apparatus according to claim 2, wherein the drawing member driven in the sheet feeding direction nips the envelope before a low-stiffness portion of the envelope being conveyed reaches the nip portion by the separation member and the envelope is bent by a displacement between its upper and lower surfaces, and, at the same time, pull back a displacement on the upper or lower surface of the envelope in the sheet feeding direction.

5. The feeding/separation apparatus according to claim 2, wherein the drawing member is disposed on the same side as the separation member in terms of the upper and lower surfaces of the envelope, and driven in the sheet feeding direction to generate a higher frictional force and a larger conveyance amount than the separation members.

6. The feeding/separation apparatus according to claim 1, wherein a conveyance member for conveying the recording medium in the sheet feeding direction is disposed downstream of the separation member, and

wherein the drawing member is disposed between the nip portions by the separation member and the nip portion by the conveyance member.

7. The feeding/separation apparatus according to claim 1, wherein the drawing member can be used also as conveyance member for conveying the recording medium in the sheet feeding direction.

8. The feeding/separation apparatus according to claim 1, wherein the feeding mechanism and the separation mechanism are driven by a common motor for driving the drawing members.

9. A recording apparatus for recording an image on a recording medium by using recording heads based on image information, the recording apparatus comprising the sheet feeding/separation apparatus according to claim 1.

10. An envelope conveyance apparatus comprising:

a plurality of conveyance belts disposed in a direction intersecting the conveyance direction and configured to apply a conveyance force in the conveyance direction to the lower surface of an envelope;

a plurality of separation belts disposed in a direction intersecting the conveyance direction and configured to apply a conveyance force in a direction opposite to the conveyance direction to the upper surface of the envelope; and

a conveyance rotating body disposed downstream of the conveyance belts and configured to apply a conveyance force in the conveyance direction to the second surface,

wherein each separation belt comes closer to each conveyance belt on the more downstream side,

wherein the downstream-side end of each separation belt partly enters between one of the conveyance belts and another one adjacent thereto, and

wherein the downstream-side end of each separation belt is supported so as to be movable in a direction of separation from each conveyance belt.

11. The envelope conveyance apparatus according to claim 10, wherein the separation belts are downwardly biased.

12. The envelope conveyance apparatus according to claim 10, further comprising:

a platen facing the conveyance rotating body; and

a plurality of conveyance rotating bodies disposed in a direction intersecting the conveyance direction so that each conveyance rotating body partly enters each of a plurality of concave portions formed on the platen.

13. The envelope conveyance apparatus according to claim 12, wherein each conveyance rotating body is disposed in line with any one of the plurality of separation belts in the conveyance direction.