GB2231842A

GB2231842A - Cleaning elements in electrophotographic copiers

Info

Publication number: GB2231842A
Application number: GB9013560A
Authority: GB
Inventors: Mitsuru Ogura; Takeshi Yoshida; Shoichiro Yoshiura
Original assignee: Sharp Corp
Current assignee: Sharp Corp
Priority date: 1986-05-16
Filing date: 1990-06-18
Publication date: 1990-11-28
Anticipated expiration: 2007-05-15
Also published as: GB9013560D0; GB2231842B

Abstract

An electrophotographic copier has a removable process module including at least the photosensitive drum 7, a corona discharge wire 3 for charging the drum and pads 1a, 1b which may be moved along the wire to clean it. When cleaning the wire 3, the pads are forced into contact therewith by projections 16a, 16b engaging the charger housing 4, but when inoperative the projections move into recesses 4b to allow the pads to come out of contact with the wire. <IMAGE>

Description

TITLE OF THE INVENTION: ELECTROGRAPHIC IMAGE RECORDING APPARATUS BACKGROUND OF THE INVENTION: Field of the Invention: The present invention relates to an electrographic image recording apparatus . such as a copying machine and, more particularly, to a mechanism for cleaning both a charging wire disposed in a charger to charge the surface of a photosensitive drum and a convergent optical system which forms a focused image of an original on the drum surface.

Description of the Prior Art: In the known electrophotographic copying machine using a photosensitive drum and a toner, there are provided a developing unit for depositing the toner from a developer tank onto the drum surface and a cleaning unit for removing the remaining toner from the drum surface after transfer of the developed toner image to a copy paper. In this structure, however, the toner is prone to scatter from such units during the copying process and thereby suspends throughout the space in the copying machine.Consequently, during long-term use of the copying machine, such suspending toner is deposited on a charging wire of a charger furnished to charge the drum surface and also on the surface of a convergent optical system employed to form a focused image of an original on the drum surface, hence deteriorating the charging efficiency of the charger and reducing the amount of light of an optical image obtained by the convergent optical system. For the purpose of preventing deterioration of the copy image, it has been customary heretofore to periodically clean the charging wire of the charger and the surface of the convergent optical system.

However, in the conventional copying machine, generally the charger needs to be taken out therefrom for cleaning, while the convergent optical system-ls cleaned at the time of maintenance service executed for other components in the machine. Consequently some labor and time are required for cleaning such two components to eventually impede quick periodic maintenance service.

SUMMARY OF THE INVENTION: It is an object of the present invention to provide an improved copying machine which realizes simultaneous cleaning of both a charging wire of a charger and a convergent optical system in a simplified procedure.

In a copying machine equipped with a charger for charging the surface of a photosensitive drum and a convergent optical system for forming a focused image of an original on the drum surface, the feature of the present invention resides in the provision of a cleaning unit which consists of first cleaner members holding therebetween a charging wire stretched with tension in the charger and a second cleaner member kept in contact with the surface of the convergent optical system, wherein such cleaner members are so supported as to be movable in the longitudinal direction of the charging wire and the convergent optical system.

Due to the structure mentioned above, the charging wire stretched in the charger is held between the first cleaner members, while the convergent optical system is retained in contact with the second cleaner member. Since such first and second cleaner members are so supported as to be movable in the longitudinal direction of the charging wire and the convergent optical system, all the cleaner members are moved together to execute simultaneous cleaning of the charging wire and the convergent optical system.

Furthermore, because of the advantage that desired cleaning is executable with both the charger and the optical system anchored in the copying machine, the whole mechanism can be shaped in smaller dimensions with facility by uniting the charger with the photosensitive drum and incorporating the cleaner unit therein.

BRIEF DESCRIPTION OF THE DRAWINGS: The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention and wherein: Fig. 1 illustrates the structure of a principal mechanism in an exemplary copying machine embodying the present invention; Fig. 2 is a perspective view of an image forming unit shown in Fig. 1; Fig. 3 is a perspective view illustrating the relationship between a charger and a first cleaner unit; and Fig. 4 (A), (B) are top views each illustrating the relationship of Fig. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT: Fig. 1 illustrates the structure of a principal mechanism in an exemplary copying machine embodying the present invention.

In the periphery of a photosensitive drum 7, there are disposed components required for a copying process. A lamp 20 serves to remove electric charge by irradiating light to the surface of the photosensitive drum 7, and a charging wire 3 stretched substantially in the center of a charger case 4 causes corona discharge upon application of a DC high voltage thereto to charge the surface of the photosensitive drum 7.

A convergent optical system 5 is disposed between an original table 6 and the photosensitive drum 7 so as to form on the drum 7 a focused image of an original placed on the table 6.

As a result, a latent image of the original is formed on the drum 7, and a toner is deposited thereon by an unshown developing unit. Subsequently the toner image thus obtained is transferred to a copy paper by a transfer charger. A waste toner collector 21 scrapes and collects the remaining toner from the surface of the drum 7 by the use of a blade 22. When the toner collector 21 is fully loaded with the waste toner, a pin 23 projects to turn on or off a full-load sensing microswitch disposed above.

First cleanser members la, lb are, attached to a support member 11 and are disposed in the charger case 4 to hold the charging wire 3 therebetween. Meanwhile, a second cleaner member 2 is attached to another support member 10 and is disposed in contact with one surface of the convergent optical system 5 opposite to the photosensitive drum. The support members 10, 11 are connected with each other by means of a guide plate 17 and are retained to be movable in the longitudinal direction (vertical to the drawing paper face) of the charging wire 3 and the convergent optical system 5 along the guide plate 17.

In Fig. 1, all the components except the charge removing lamp 20, convergent optical system 5 and original table 6 are integrated with one another to constitute an image forming unit.

Fig. 2 is a perspective view of such image forming unit seen from above.

A connecting rod 12 extends through a hole 14 formed in a frame, and a knob 15 is attached thereto.

When the support member 10 is pulled in the direction of an arrow A by the knob 15, the first and second cleaner members are moved on a straight line along an opening 13 and the guide plate 17 shown in Fig. 1, thereby cleaning the charging wire and the surface of the convergent optical system.

Fig. 3 is a perspective view illustrating the relationship between the charger and the first cleaner members.

The support members lla, llb are kept in contact with inner walls of the charger case 4 in such a manner as to slide therealong in accordance with the movement of the cleaner unit. The first cleaner members la, lb are attached to projections 18a, 18b of the support member 11 respectively so that, when the cleaner unit is moved, the first cleaner members la, lb holding the charging wire 3 therebetween serve to remove the toner and so forth from the surface of the wire 3.

Fig. 4 (A), (B) are top views of Fig. 3 illustrating the relationship between the charger and the first cleaner members.

Two raised portions 4a, 4b are formed on the two sides of the charger case 4. Meanwhile, projections 16a, 16b kept in contact with inner walls of the charger case 4 are attached to the fore ends of the projections 18a, 18b besides the first cleaner members la, lb. In the estate shown in Fig. 4 (A), the first cleaner members la, lb are spaced apart from the charging wire 3. However, when the state of Fig. 4 (B) is caused with movement of the cleaner unit, the projections 16a, 16b are disengaged from the raised portions 4a, 4b respectively so that the outer width thereof is narrowed to be equal to the inner width of the case 4. Consequently the first cleaner members la, lb come to hold the charging wire 3 therebetween.Thus, if the mechanism is so contrived that the cleaner unit is fixed at the position in Fig. 4 (A) under normal condition of use, then it becomes possible to charge the drum surface properly while keeping the first cleaner members la, lb away from the charging wire 3 without affecting its corona discharge.

In this embodiment where the cleaner unit is integrated with the charger and the photosensitive drum, there is attained an advantage that no excessive force is applied from the first cleaner members tithe charging wire during the cleaning operation, hence eliminating the trouble of breakage of the wire.

while only certain embodiments of the present invention have been described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the present invention as claimed.

Claims

CLAIMS:

1. An electrographic image recording apparatus in which an electrostatic latent image is formed on a photosensitive image recording member by a process involving electrostatically charging the surface of said member using a charger having a discharge element, and in which a developed image corresponding to the latent image is formed, the apparatus comprising cleaning means which is moveable relative to the discharge element to clean said discharge element.

2. Apparatus according to claim 1 wherein said discharge element comprises an elongate discharge wire.

3. Apparatus according to claim 1 or claim 2 wherein said cleaning means is displaceable between a first position relative to the discharge element in which it contacts said discharge element, said relative movement being effected with said cleaning means in said first relative position, and a second relative position in which it does not contact said discharge element.

4. Apparatus according to claim 3 when dependent on claim 2 wherein said cleaning means comprises cleaner members for pinching the discharge wire therebetween in said first relative position.

5. Apparatus according to any of claims 1 to 4, including optical focusing means for focusing upon said recording member an image which is to be recorded, and further cleaning means moveable relative to the optical means for cleaning said optical means.

6. Apparatus according to claim 5 wherein said first-mentioned and further cleaning means are coupled together so as to move simultaneously for cleaning said discharge element and said optical focusing means, respectively.

7. An image forming unit for an electrographic image recording apparatus according to any of claims 1 to 6, the unit having a casing which is removably located or locatable within a main body of the apparatus, and said discharge element and the cleaning means therefor being mounted to said casing.

8. An apparatus according to claim 7 wherein said further cleaning means is mounted for movement in a direction along said discharge wire.

8. An image forming unit according to claim 7 for an apparatus according to claim 5 or claim 6 wherein said further cleaning means is mounted to said casing.

9. An electrographic image recording apparatus in which a latent image is formed on a photosensitive image recording member by a process involving focusing upon said image recording member an image which is to be recorded, using an optical focusing means, and in which a developed image corresponding to the latent image is formed, the apparatus comprising cleaning means which is moveable relative to the optical focusing means to clean said optical focusing means.

10. An image forming unit for an electrographic image recording apparatus according to claim 9, said unit having a casing which is removably located or locatable within a main body of the apparatus, and said cleaning means for said optical focusing means being mounted to said casing.

11. A copying machine comprising a charger for charging the surface of a photosensitive drum and a convergent optical system for forming a focused image of an original on the surface of said drum, said copying machine further including a cleaner unit which consists of first cleaner members holding therebetween a charging wire stretched in said charger, and a second cleaner member kept in contact with the surface of said convergent optical system, wherein said cleaner members are so supported as to be moveable in the longitudinal direction of said charging wire and said convergent optical system.

12. A copying machine substantially as hereinbefore described with reference to the accompanying drawings.

13. An image forming unit for a copying machine, substantially as hereinbefore described with reference to the accompanying drawings.

CLAIMS:

1. An electrographic image recording apparatus comprising a photosensitive image recording member, means for forming an electrostatic latent image on said recording member by a process involving electrostatically charging the surface of said recording member using a charger having a discharge element, means for forming a developed image corresponding to said latent image, and cleaning means which is moveable relative to the discharge element to clean said discharge element, wherein said photosensitive image recording member, said charger and said cleaning means are incorporated in a replaceable image forming unit which is removably located within the main body of the apparatus.

2. Apparatus according to claim 1 wherein said discharge element comprises an elongate discharge wire, and said cleaning means is mounted for movement in a direction along said discharge wire.

3. Apparatus according to claim 1 or claim 2 wherein said cleaning means is displaceable between a first position relative to the discharge element in which it contacts said discharge element, said relative movement between said first cleaning means and said discharge element being effected with said first cleaning means in said first relative position, and a second relative position in which it does not contact said discharge element.

4. Apparatus according to claim 3 when dependent on claim 2 wherein said first cleaning means comprises first and second cleaner members for pinching the discharge wire therebetween in said first relative position.

5. Apparatus according to claim 4 wherein said charger further comprises an elongate charger case having mutually opposed parallel side walls, said discharge wire being disposed between said side walls and extending along and within said charger case, wherein said cleaner means includes first and second support members disposed on respective sides of the discharge wire, which have portions in sliding engagement with the inside surfaces of the respective said side walls and which carry the respective first and second cleaner members, said side walls having respective ones of a pair of recessed portions at a given longi3tudinal position of the case and the said portions of said first and second support members being engageable in said respective recessed portions when the cleaning means reaches said given longitudinal position to effect displacement of the cleaning means to said second position by moving said cleaner members so as to release their pinch of the discharge wire.

6. An image forming unit for an electrographic image recording apparatus according to any of claims 1 to 5, the unit having a casing which is removably located or locatable within a main body of the apparatus, and said photosensitive image recording member, charger and cleaning means being mounted to said casing.

7. An apparatus according to any preceding claim, and further including an optical focusing means for focusing on the surface of said image recording member an image which is to be recorded, and a further cleaning means for cleaning a surface of said optical focusing means, said further cleaning means being incorporated in said image forming unit and being mounted for movement relative to said optical focusing means for cleaning said optical focusing means.