JP2000039809A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an excellent image by surely driving the image carrier being excellent in durability and operability and surely obtaining a stable contact state with respect to a contact member, and preventing twist deformation of the image carrier. SOLUTION: This image forming device is constituted so that the image carrier 140 in a flexible thin cylindrical shape is supported by a pair of disk shape members that itself is not rotated. It is driven from one side being attached to the shaft 110 in the inner side supporting at the contact position that the cleaning blade and a charge roller are held in contact with regard to the image carrier 140 from the outside thereof. The image carrier 140 is disposed in rotatably with regard to the back up drum supporting the image carrier 140 from inward with regard to the shaft 110 across an eccentric bush 154, and moreover, the coefficient of friction μ2 between the image carrier 140 and the back up drum 150 is made larger than the coefficient of friction μ1 between the cleaning blade and the image carrier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a printer, a facsimile, and a copying machine for forming an image by using an electrophotographic technique.

[0002]

2. Description of the Related Art Generally, an image forming apparatus using an electrophotographic technique includes a photosensitive member having a photosensitive layer on an outer peripheral surface, a charging device for uniformly charging the outer peripheral surface of the photosensitive member, and one charging device. Exposure means for selectively exposing the charged outer peripheral surface to form an electrostatic latent image, and applying a toner as a developer to the electrostatic latent image formed by the exposure means to form a visible image Developing means for forming a toner image, a transferring means for transferring the toner image developed by the developing means to a transfer medium such as paper, and a cleaning member for removing a developer remaining on the outer peripheral surface of the photoreceptor after the transfer. have.

As the photoreceptor, a hard photoreceptor drum having a photosensitive layer formed on the outer peripheral surface and a flexible photoreceptor belt having a photosensitive layer formed on the surface are generally known.

As means for applying toner to the electrostatic latent image on the surface of the photoreceptor, toner is carried on the surface of a developing roller, and the developing roller is brought into contact with the surface of the photoreceptor, Means of approaching in a spaced state are generally known, and as the developing roller,
A hard material and an elastic material are known.

[0005] A hard photoconductor drum is used as the photoconductor,
Also, when a hard developing roller is used,
There is naturally a limit in manufacturing the photoreceptor drum and the developing roller with high precision, and errors always occur. Therefore, it is difficult to bring the both into uniform contact or close to each other at a uniform minute interval. In particular, it is extremely difficult to uniformly contact the photosensitive drum and the developing roller, which are hard members, and there is a gap locally, which causes uneven development, or the photosensitive drum and the developing roller are pressed more strongly than necessary. There is a problem that the roller is damaged.

Therefore, it is not usually practiced that both the photosensitive member and the developing roller are made of a hard material. When a hard photosensitive drum is used as the photosensitive member, the developing roller is made of an elastic material. In the case where a hard developing roller is used, a photosensitive belt having flexibility is used as a photosensitive member.

However, when the developing roller is made of an elastic material, there is a problem that the toner is easily scattered with the rotation of the developing roller.

When a photoreceptor belt is used as the photoreceptor, at least two rollers are required to support the photoreceptor belt, which not only complicates the structure but also increases the size of the apparatus. There was a problem.

Therefore, it is desired to solve such a problem at the same time.

As a device that meets such a demand, a photoconductor driving device described in Japanese Patent Application Laid-Open No. 4-188164 has been conventionally known.

FIGS. 15A and 15B are views showing the photoconductor driving device. FIG. 15A is a side view and FIG. 15B is a perspective view.

The photosensitive member driving device has a photosensitive member belt 20 formed as a cylindrical thin film sheet and an outer peripheral length shorter than the inner peripheral length of the photosensitive belt 20. Driving roller 21 which is inside and is driven to rotate
And the coefficient of friction between the photoconductive belt 20 and the driving roller 2
1 and the coefficient of friction between the photosensitive belt 20 and the photosensitive belt 20. The photosensitive belt 20 is slidable while the photosensitive belt 20 is in close contact with the drive roller 21 within a predetermined range in the circumferential direction of the drive roller 21. And a pressing member 22 for pressing. In FIG. 15, 24 is a charger, 25 is an exposure device, 26 is a developing roller, 27 is a transfer charger, 28
Denotes a cleaning roller.

According to such a photosensitive member driving device, the photosensitive member belt 20 is driven by the pressing member 22 in a state of being partially adhered to the surface of the drive roller 21, and the pressing member 2
In a portion where there is no 2, a bend 23 is formed due to a difference in circumferential length from the drive roller 21.

For this reason, the photoreceptor belt 20 can be used as a hard material because the hardness of the photoreceptor belt 20 is simulated by the hardness of the driving roller 21 at the contact portion with the pressing member 22, and there is no pressing member 22. Since the flexure 23 is formed in the portion, it can be used as an elastic body.

Therefore, according to this apparatus, the cleaning roller 28 made of an elastic material can be brought into contact with the contact portion of the photosensitive belt 20 with the pressing portion 22, and the bending portion 23 is made of a hard material. The developing roller 26 can be brought into contact.

The contact of the developing roller 26 is stably performed with a sufficient nip width and a low pressure contact force even when the developing roller 26 is made of a hard material because the bending 23 acts as an elastic body. .

That is, according to this apparatus, even if a hard developing roller is used, the photosensitive member and the developing roller are not damaged, and the apparatus can be prevented from being enlarged.

An apparatus similar to this apparatus is disclosed in
No. 27859, JP-A-6-258989, and the like.

[0019]

SUMMARY OF THE INVENTION The above-mentioned JP-A-4-14-1
In the photoconductor driving device described in JP-A-88164, the photoconductor belt 20 is guided by the pressing member 22 provided partially on the peripheral portion of the photoconductor belt 20. When approaching 22,
At the entrance portion 22a, bending stress is likely to be generated at the peripheral portion (edge portion) of the photoreceptor belt 22, whereby the end portion of the photoreceptor belt 20 is likely to be broken, cracked, or peeled of the photosensitive layer. (Poor in durability). As a result, there is a problem that the photoreceptor belt 20 may be destroyed from the edge portion, or may cause a serious image defect although it does not lead to the destruction.

The photoreceptor belt 20 must be handled as a single unit until the photoreceptor belt 20 is incorporated in the apparatus as shown in FIG. However, since the photoreceptor belt 20 is formed as a cylindrical thin film sheet as described above and does not have sufficient rigidity, there is a problem that it is difficult to handle the photoreceptor belt 20.

Further, in the above apparatus, the photosensitive belt 20
Since the flexure 23 is formed at a portion where the pressing member 22 that presses both ends of the photoconductor belt 20 is not formed, the photosensitive belt 20 and the driving roller 21 are formed at both ends of the portion where the flexure 23 is formed. Opening 2 between
9 is formed.

For this reason, the toner floating in the apparatus,
Foreign substances such as toner external additives and paper powder easily enter between the photoreceptor belt 20 and the drive roller 21 through the openings 29 and 29, and the friction between the photoreceptor belt 20 and the drive roller 21 due to the entry of these foreign substances. There is a problem that the force is reduced and the photosensitive belt 20 may not be driven.

An object of the present invention is to solve the above-mentioned various problems, and an object of the present invention is to obtain a reliable and stable contact state with a contact member, and to improve durability and handleability. An object of the present invention is to provide an image forming apparatus which can drive an image carrier (for example, a photoconductor) without fail.

[0024]

According to a first aspect of the present invention, there is provided an image forming apparatus comprising: a shaft which does not rotate by itself; and a pair of disk-shaped members rotatably mounted on the shaft. A member, a flexible thin-walled cylindrical image carrier that is supported and fixed at both ends by the pair of disk members, and is rotationally driven together with the disk member; and the shaft inside the image carrier. The abutting member is attached to the shaft so as to be rotatable about an axis parallel to the abutting member, and abuts against an image carrier from outside thereof and abuts against the image carrier as a load against the rotation of the image carrier. An image carrier unit provided with a backup drum for supporting the image carrier from the inside at a position, and an image carrier rotational driving means provided at one end of the image carrier unit; Than the coefficient of friction between Wherein the direction of the friction coefficient between the backup drum and the image bearing member is constructed larger.

According to the second aspect of the present invention, there is provided the image forming apparatus of the first aspect.
In the above image forming apparatus, the backup drum is configured to be longer than the contact member in the axial direction of the shaft.

According to the third aspect of the present invention, there is provided the image forming apparatus according to the first aspect.
3. The image forming apparatus according to 2, wherein the backup drum has an outer diameter slightly smaller than the inner diameter of the image carrier, and is rotatably supported on the shaft via an eccentric bearing member. It is characterized by.

[0027]

According to the image forming apparatus of the first aspect, the following effects can be obtained.

(A) In the image carrier unit of this image forming apparatus, both ends of a thin-walled cylindrical image carrier are supported and fixed by a pair of disk-shaped members rotatably mounted on an axis. When the disk-shaped member is driven to rotate,
The image carrier is reliably driven to rotate.

Further, since both ends of the image carrier are supported and fixed by a pair of disk members, the durability is excellent.

(B) The image carrier is a thin cylindrical member having flexibility and both ends are supported by a disk-shaped member. The central portion, which is not supported by, is inwardly deformable.

Therefore, a portion of the central portion of the image carrier that is not supported from the inside by the backup drum can be used as a so-called pseudo soft material, so that the member to be brought into contact with the soft material is hard. Even with rollers, etc., a reliable and stable contact state can be obtained,
The image can be reliably formed on the image carrier, or the image can be carried.

On the other hand, a contact member such as a cleaner blade is brought into contact with the outer peripheral surface of the image carrier, and at the contact position, the image carrier is supported from the inside by a backup drum. Therefore, the contact member can be reliably brought into contact.

Further, if the contact member is brought into contact with the image carrier for a long period of time without the backup drum, the thin cylindrical image carrier may be creep-deformed. According to the unit, such a fear is eliminated.

(C) In the image carrier unit, both ends of the image carrier are supported and fixed by a pair of disk-shaped members rotatably mounted on a shaft, and the image carrier unit is provided inside the image carrier. Since the backup drum is unitized by being attached to the shaft, handling of the image carrier unit itself becomes easy.

(D) This image forming apparatus has a structure in which a contact member acting as a load is disposed on an image carrier which is driven to rotate from one end side. A torsional force acts on a portion between the contact portion with the member and the drive-side end.

Since the image carrier is in the form of a thin, flexible cylinder, there is a possibility that the above-mentioned portion is deformed by the above-mentioned twisting force. The contact between the carrier and the contact member becomes inappropriate. Therefore, when the contact member is a cleaner blade, poor cleaning occurs, and when the contact member is a charging member, poor charging occurs. Further, since the deformation occurs over the entire circumference of the image carrier in the circumferential direction, the contact with another process member (not limited to a member serving as a load), for example, a developing roller becomes inappropriate. Development failure and the like will occur.

On the other hand, according to the image forming apparatus of the first aspect, the backup drum is configured to be rotatably supported around an axis parallel to the shaft. In the supporting portion for the image carrier, power from the image carrier is transmitted by contacting the outer peripheral surface with the inner peripheral surface of the image carrier, and as a result, the backup drum follows the image carrier. It will rotate. Therefore, the load on the image carrier can be reduced, and the driving torque of the image carrier can be reduced.

Therefore, the backup drum plays a role as a transmission member for transmitting the driving force acting from one end of the image carrier to the image carrier at a support portion for the image carrier. The torsional force is reduced, and as a result, the above-described deformation of the image carrier is suppressed, and image defects are less likely to occur.

In addition, since the friction coefficient between the image carrier and the backup drum is configured to be larger than the friction coefficient between the contact member and the image carrier, the backup drum with respect to the image carrier is formed. The driven rotation and the function as the power transmission member are reliably obtained, and as a result, the above-described deformation of the image carrier is reliably suppressed, and image defects are more unlikely to occur.

As described above, according to the image forming apparatus of the first aspect, a reliable and stable contact state with the contact member can be obtained, the durability and the handleability are excellent, and the image carrier is provided. Can be reliably driven.

In addition, the above-described deformation of the image carrier is suppressed, and an effect of preventing image defects from occurring is obtained.

According to the image forming apparatus of the second aspect, in the image forming apparatus of the first aspect, the backup drum is configured to be longer than the contact member in the axial direction of the shaft. By supporting the above-mentioned portion of the image carrier, that is, the portion where the deformation is likely to occur, by the backup drum, the deformation is further suppressed.

Therefore, the situation in which the contact state between the image carrier and the contact member becomes inappropriate is less likely to occur, and as a result, image defects are more unlikely to occur.

According to a third aspect of the present invention, in the image forming apparatus of the first or second aspect, the backup drum has an outer diameter slightly smaller than an inner diameter of the image carrier. Since it is configured to be rotatably supported on the shaft via an eccentric bearing member, the following operation and effect can be further obtained.

(E) Since the backup drum is rotatably supported on the shaft via an eccentric bearing member, the structure is simple and the assembly can be easily performed. Therefore, it can be produced with high accuracy.

(F) The backup drum has an outer diameter slightly smaller than the inner diameter of the image carrier, and is rotatably supported on the shaft via an eccentric bearing member. On the other hand, the image carrier can be supported over a wide range from the inside at the contact position where the contact member contacts from the outside. Therefore, the function as the power transmission member described above can be obtained more favorably, and image defects can be more reliably prevented.

[0047]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view showing an embodiment of an image forming apparatus according to the present invention, FIG. 2 is an enlarged view of an image carrier unit and a part of the periphery thereof, and FIG.
FIG. 3 is an enlarged partial sectional view taken along the line III.

First, the outline of the image forming apparatus will be described, and then the image carrier unit will be described in detail.

This image forming apparatus is an apparatus capable of forming a full-color image using a developing device using four color toners of yellow (Y), cyan (C), magenta (M) and black (K). .

In FIG. 1, reference numeral 100 denotes an image carrier cartridge in which an image carrier unit (see 101 in FIG. 2) is incorporated. In this embodiment, the photosensitive member 140 is configured as a photosensitive member cartridge, and the photosensitive member 140 is rotationally driven in a direction indicated by an arrow in FIG.

The photoreceptor 140 has a thin cylindrical conductive substrate 140b (see FIG. 3) which will be described in detail later, and a photosensitive layer 140c formed on the surface thereof.

Around the photoreceptor 140, along the direction of rotation thereof, a charging roller 160 as charging means, which is one of the contact members, and a developing device 10 (Y, C,
M, K), the intermediate transfer device 30, and the cleaning unit 170 are arranged.

The charging roller 160 contacts the outer peripheral surface of the photosensitive member 140 to uniformly charge the outer peripheral surface. On the outer peripheral surface of the uniformly charged photoconductor 140, a selective exposure L1 according to desired image information is performed by the exposure unit 40,
By the exposure L1, an electrostatic latent image is formed on the photoconductor 140.

This electrostatic latent image is developed by applying toner in the developing device 10 and becomes a visible image.

As a developing device, a developing device 10 for yellow is used.
Developing device 10C for Y and cyan, developing device 10 for magenta
A developing device 10K for M and black is provided. These developing units 10Y, 10C, 10M, and 10K are:
Each is configured to be swingable, so that only the developing roller 11 of one developing unit can selectively contact the photoconductor 140. Therefore, these developing devices 10
Develops an electrostatic latent image on the photoconductor 140 by applying any one of yellow, cyan, magenta, and black toners to the surface of the photoconductor 140. The developing roller 11
Is constituted by a hard roller, for example, a metal roller having a roughened surface, or a hard resin roller.

The developed toner image (visible image) is transferred onto the intermediate transfer belt 36 in the intermediate transfer device.

The cleaning means 170 includes a cleaner blade 171 as a contact member for scraping off the toner T (see FIG. 9) remaining and adhering to the outer peripheral surface of the photosensitive member 140 after the transfer, and the cleaning blade 171. A receiving portion 172 for receiving the scraped toner;

The intermediate transfer device 30 includes a driving roller 31 and
Four driven rollers 32, 33, 34, 35 and an endless intermediate transfer belt 36 stretched around these rollers.
And

The drive roller 31 has a gear (not shown) fixed to the end thereof and a drive gear 190 for the photosensitive member 140.
(See FIG. 4), the photosensitive member 1
The intermediate transfer belt 36 is driven to rotate at substantially the same peripheral speed as the photosensitive member 140 in the direction indicated by the arrow in FIG.

The driven roller 35 is disposed at a position where the intermediate transfer belt 36 is pressed against the photosensitive member 140 by its own tension between the driven roller 35 and the driven roller 31.
A primary transfer portion T1 is formed at a pressure contact portion between the intermediate transfer belt 36 and the intermediate transfer belt 36. The driven roller 35 is disposed near the primary transfer portion T1 on the upstream side in the circulation direction of the intermediate transfer belt 36.

The driving roller 31 has an intermediate transfer belt 36
A primary transfer voltage is applied to a conductive layer 36a (see FIG. 3) of the intermediate transfer belt 36, which will be described later, via the electrode roller.

The driven roller 32 is a tension roller, and urges the intermediate transfer belt 36 in the direction of its tension by urging means (not shown).

The driven roller 33 is a backup roller that forms the secondary transfer portion T2. A secondary transfer roller 38 is opposed to the backup roller 33 via an intermediate transfer belt 36. The secondary transfer roller 38
It can be moved toward and away from the intermediate transfer belt 36 by a contacting / separating mechanism (not shown). A secondary transfer voltage is applied to the secondary transfer roller 38.

The driven roller 34 is a backup roller for the belt cleaner 39. Belt cleaner 39
Is a cleaner blade 39 which comes into contact with the intermediate transfer belt 36 and scrapes off the toner remaining and adhering to the outer peripheral surface thereof.
a, and a receiving portion 39b for receiving the toner scraped off by the cleaner blade 39a. The belt cleaner 39 can be moved toward and away from the intermediate transfer belt 36 by a contact / separation mechanism (not shown).

As shown in FIG. 3, the intermediate transfer belt 36 is a multilayer belt having a conductive layer 36a and a resistance layer 36b formed on the conductive layer 36a and pressed against the photosensitive member 140. ing. The conductive layer 36a is formed on an insulating substrate 36c made of a synthetic resin, and a primary transfer voltage is applied to the conductive layer 36a via the above-described electrode roller. The conductive layer 36a is exposed in the form of a strip by removing the resistance layer 36b in the form of a strip at the side edge of the belt 36, and the electrode roller comes into contact with this exposed portion.

In the process of circulating the intermediate transfer belt 36, the toner image on the photosensitive member 140 is transferred onto the intermediate transfer belt 36 in the primary transfer section T1, and the toner image transferred onto the intermediate transfer belt 36 is Is transferred to a sheet (recording material) S, such as a sheet, supplied between the secondary transfer roller 38 and the secondary transfer unit T2.

The sheet S is fed from the sheet feeding device 50,
The toner is supplied to the secondary transfer portion T2 at a predetermined timing by the gate roller pair G. 51 is a paper feed cassette, and 52 is a pickup roller.

The sheet S to which the toner image has been transferred in the secondary transfer portion T2 passes through the fixing device 60, where the toner image is fixed, passes through the paper discharge path 70, and is formed on the case 80 of the apparatus main body. The sheet is discharged onto the received sheet receiving portion 81. In this image forming apparatus, as a paper discharge path 70,
It has two paper discharge paths 71 and 72 independent of each other, and the sheet that has passed through the fixing device 60 is discharged through one of the paper discharge paths (71 or 72). The paper discharge paths 71 and 72 also constitute a switchback path. When an image is formed on both sides of the sheet, the sheet once entering the paper discharge path 71 or 72 passes through the return path 73. Then, the sheet is fed again to the secondary transfer portion T2.

The outline of the operation of the entire image forming apparatus as described above is as follows.

(I) When a print command signal (image forming signal) from a host computer (not shown) (personal computer or the like) (not shown) is input to the control section 90 of the image forming apparatus, the photosensitive member 140 and each roller of the developing device 10 11 and the intermediate transfer belt 36 are driven to rotate.

(Ii) The outer peripheral surface of the photosensitive member 140 is uniformly charged by the charging roller 160.

(Iii) The exposure unit 40 selectively exposes the outer peripheral surface of the uniformly charged photoreceptor 140 in accordance with the image information of the first color (for example, yellow). An image is formed.

(Iv) Only the developing roller of the developing device 10Y for the first color (for example, yellow) comes into contact with the photoconductor 140, whereby the electrostatic latent image is developed, and the first color (for example, yellow) is developed. Is formed on the photoconductor 140.

(V) A primary transfer voltage having a polarity opposite to the charging polarity of the toner is applied to the intermediate transfer belt 36, and the toner image formed on the photosensitive member 140 is transferred to the intermediate transfer belt 36 at the primary transfer portion T1. Is transferred to At this time, the secondary transfer roller 38 and the belt cleaner 39 are separated from the intermediate transfer belt 36.

(Vi) After the toner remaining on the photosensitive member 140 is removed by the cleaning means 170,
The photoconductor 140 is neutralized by the neutralization light L2 from the neutralization unit 41 (see FIG. 2).

(Vii) The above operations (ii) to (vi) are repeated as necessary. That is, the second color, the third color, the fourth color,
Is repeated on the intermediate transfer belt 36 to form a toner image corresponding to the content of the print command signal.

(Viii) The sheet S is supplied from the sheet feeding device 50 at a predetermined timing, and immediately before or after the leading end of the sheet S reaches the secondary transfer portion T2 (in short, at a desired position on the sheet S, Secondary transfer roller 38) (at the timing when the toner image on intermediate transfer belt 36 is transferred)
Is pressed against the intermediate transfer belt 36 and a secondary transfer voltage is applied, so that the toner image on the intermediate transfer belt 36 (basically, a full-color image in which four color toner images are superimposed) is transferred onto the sheet S. Is done. Further, the belt cleaner 39 comes into contact with the intermediate transfer belt 36, and the toner remaining on the intermediate transfer belt 36 after the secondary transfer is removed.

(Ix) The toner image is fixed on the sheet S by passing the sheet S through the fixing device 60, and thereafter, the sheet S is directed to a predetermined position (or to the sheet receiving portion 81 in the case of not double-sided printing). In the case of double-sided printing, the sheet is conveyed to the return path 73 via the switchback path 71 or 72).

Next, the image carrier cartridge 100 will be described.

FIG. 4 is an exploded perspective view of the image carrier cartridge, and FIG. 5 is a partially omitted exploded perspective view as viewed from another angle.

As shown in FIG. 4, the image carrier cartridge 100 includes an image carrier unit 101 and a charging roller 16.
0, a cleaner blade 171, and a cartridge case 200 in which the image carrier unit 101, the charging roller 160, the cleaner blade 171 and the like are incorporated.

The image carrier unit 101 will be described first.

FIG. 6 is a sectional view of the image carrier unit 101.

As shown in FIG. 6, the image carrier unit 101 has a shaft 110 which does not rotate by itself, a pair of disk-shaped members 120 and 130 which are rotatably mounted on the shaft 110, and These pair of disc-shaped members 12
Disc-shaped member 1 having both ends supported and fixed by 0, 130
A thin cylindrical image carrier 140 having flexibility that rotates together with the image carriers 20 and 130, an abutting member attached to the shaft 110 inside the image carrier 140, and abutting against the image carrier 140 from outside. Blade 171 as a
(See FIG. 8), and a backup drum 150 that supports the image carrier 140 from the inside at the contact position where the charging roller 160 contacts.

Each of the pair of disk-shaped members 120 and 130 is rotatably provided on the shaft 110 via a bearing 114, and the outer peripheral surfaces 121 and 131 of these disk-shaped members 120 and 130 are used to hold the image carrier. 140 at both ends 14
1 is supported and fixed.

FIG. 7 shows the fixing structure. FIG. 7 shows an end portion 14 of the image carrier 140 with respect to one disc-shaped member 120.
1 shows the fixing structure, but the other disc-shaped member 130
The same applies to the fixing structure of the end 141 of the image carrier 140 with respect to.

As shown in the figure, the outer diameter D 3 of the outer peripheral surface 121 of the disc-shaped member 120 is formed to be slightly larger than the inner diameter D 2 of the image carrier 140, and The disk-shaped member 120 is press-fitted. A tapered surface 121a is formed inside the disc-shaped member 120 so that the press-fitting is performed smoothly. By this press-fitting, the image carrier 140 and the disc-shaped member 120 are connected substantially satisfactorily, but a fixing ring 180 is provided to further secure the connection between the two.

The fixing ring 180 has a ring-shaped disk portion 181 and a short cylindrical portion 182 integrated therewith. The disk portion 181 is provided with a plurality of (for example, eight (only one is shown)) screw insertion holes 183 at equal intervals in the circumferential direction. The end part 141 of the image carrier 140 and the outer part of the disk-shaped member 120 are press-fitted into the cylindrical part 182. In order to facilitate this press-fitting, the inner peripheral surface of the cylindrical portion 182 has a tapered surface 18.
4 are formed, and a tapered surface 121b is also formed on the outer portion of the disc-shaped member 120.

The image carrier 140 first has its end 141
Into the cylindrical portion 182 of the fixing ring 180 (the fixing ring 180).
To the end 141 of the image carrier 140 and the disc-shaped member 120.
Then, the fixing ring 180 is completely fixed to the disk-shaped member 120 by fixing the fixing ring 180 to the disk-shaped member 120 with the screw 185.

Disc-shaped member 120 and fixing ring 18
0 is the outer surface of the disc-shaped member 120 and the fixing ring 180
Is formed so that a interference C is formed between the inner surface and the inner surface. Therefore, by tightening the screw 185, the edge 141a of the image carrier 140 is
20 and the cylindrical portion 18 of the fixing ring 180
2 and the inner peripheral surface (184) is securely pressed and securely fixed. Reference numeral 122 denotes a screw hole for the screw 185.

As shown in FIG. 6, the other disc-shaped member 13
A drive gear 190 is fixed to the outer side of the drive unit 0 as a rotation drive unit of the image carrier. This gear 190
Is formed separately from the disk-shaped member 130, and is fixed to the disk-shaped member 130 with a plurality of (for example, three (only one is shown)) screws 191. The gear 190 is formed integrally with a tubular portion 192, and the tubular portion 192 is
Cylindrical part 1 integrally formed outside disc-shaped member 130
33 and is supported by a shaft 110 via a bearing 114.

Therefore, the disk-shaped member 130 is rotatably supported by the shaft 110 via the bearing 114 and the cylindrical portion 192 of the gear 190.

In this embodiment, the image carrier 140 is configured as a photosensitive member, and the photosensitive layer 140 is formed on the surface (outer peripheral surface) of a flexible conductive base material 140b (see FIG. 3).
It is constituted by forming c. As the base material, for example, a nickel seamless tube manufactured by an electroforming method, an aluminum tube manufactured by impact processing, or the like can be used. The photosensitive layer is a so-called OPC (organic photoreceptor)
Can be formed by a dipping method. The flexibility, that is, the flexibility of the photoconductor 140 is such that the base material 140b
Can be determined by adjusting the thickness and diameter of the image forming apparatus, and can be appropriately set according to the image forming apparatus to be used. For example, substrate thickness 20 to 200
The thickness is appropriately set in a range of μm and a diameter of the base material of 10 to 300 mm. OPC is mainly composed of resin, and therefore is excellent in terms of flexibility. However, in order to secure adhesion to the substrate and take measures against laser light interference, an undercoat layer is formed between the substrate and the OPC. It is desirable to form As the undercoat layer, a layer in which particles capable of absorbing laser light such as zinc oxide and titanium oxide are dispersed in a resin such as a nylon resin is preferable.

The backup drum 150 is composed of a pair of side plates 151, 151 and a cylindrical member 152 whose both ends are fixed by the outer peripheral surfaces of these side plates 151, 151. The outer diameter D1 of the cylindrical member 152 is slightly smaller than the inner diameter D2 of the photoconductor 140 (for example, about 1 mm smaller).
Is formed. A bearing hole 153 is provided in the side plate 151, and an eccentric bush 154 and a bearing 155 are provided between the bearing hole 153 and the shaft 110. The eccentric bearing member according to this embodiment includes the eccentric bush 154 and the bearing 155.

The backup drum 150 is rotatably supported on the shaft 110 via an eccentric bearing member, that is, an eccentric bush 154 and a bearing 155.

The eccentric bush 154 has an eccentric amount E on the side of the cleaner blade 171 (see FIG. 8) as a contact member and the contact position where the charging roller 160 contacts (in the direction of arrow e in FIG. 8). As a result, the outer peripheral surface of the backup drum 150 (the cylindrical member 15
A portion of the outer peripheral surface 2 supports the image carrier 140 from the inside over a relatively wide range at the contact position.

[0098] The shaft 110 of the eccentric bush 154 is attached to the shaft 110.
A pin 111 for determining an eccentric direction with respect to 10 is fixed, and a groove 156 having a shape compatible with the pin 111 is formed on the inner surface of the eccentric bush 154. In this embodiment, the pin 111 and the groove 156
Thus, a positioning means for determining the position of the backup drum 150 around the shaft 110 is configured. Pin 111
Since the protruding length of the eccentric bush 154 from the shaft 110 is different between the one end side and the other end side, the eccentric bush 154 is surely fitted in the direction of arrow e in FIG. Mounted eccentrically. The pin 111 may be fixed to the shaft 110 by press-fitting into a through hole provided in the shaft 110,
It may be configured integrally with the shaft 110.

Since the backup drum 150 is rotatably supported on the shaft 110 via the eccentric bush 154 and the bearing 155, the image carrier unit 101 is incorporated in the cartridge case 200 as shown in FIG. When the image carrier 140 is driven to rotate, the outer peripheral surface 152 a of the cylindrical member 152 abuts on the inner peripheral surface 140 a of the image carrier 140 at the contact position of the cleaning blade 171 and the like, thereby following the image carrier 140. And rotate.

As shown in FIG. 6, a compression coil spring 102 for preventing backlash is provided between one eccentric bush 154 and the bearing 114.

The image carrier unit 101 as described above is
In a state as shown in FIG.

FIG. 4 and FIG.
As shown in FIG. 8 and FIG.
A case main body A having a main connecting portion 230 connecting the back sides of the side portions 210 and 220, and a sub connecting portion 240 connecting the front lower portions of the side portions 210 and 220;
The case body A includes side covers 250 and 260 that cover the outside of the side portions 210 and 220, and a roller cover 270 that covers the charging roller 160 incorporated in the case body A.

The case body A is an integrally molded product made of a synthetic resin.

In the case body A, first, the cleaning means 170 is incorporated, then the charging roller 160 is incorporated, and thereafter, the image carrier unit 101 is incorporated.

As shown in detail in FIG. 9, the cleaning means 170 includes a cleaner blade 171 for scraping off the toner T remaining on and adhering to the outer peripheral surface of the photosensitive member 140.
Receiving portion 172 for receiving toner T scraped off by cleaner blade 171; and receiving portion 172
And a toner conveying screw 173 as conveying means for conveying the scraped-off toner.

The upper part of the cleaner blade 171 is fixed to the blade holder 174. The blade holder 174 has arms 174a, 17 provided at both ends thereof.
4a (only one is shown) is swingably attached to the side portions 210 and 220 by shafts 211 and 221 (only 211 is shown). A blade urging spring (compression coil spring) 175 is provided between the main connecting portion 230 and the blade holder 174. When the image carrier unit 101 is incorporated into the cartridge case 200 as shown in FIG. The tip (edge) of the cleaner blade 171 is moved by the urging force of the blade urging spring 175 to the photosensitive member 14.
0 surface.

According to such a structure, the blade 171
The blade 171 can be pressed against the photoreceptor 140 at a constant pressure regardless of the shape accuracy and the rubber hardness. Further, filming of the photoconductor 140 can be prevented by reducing pressure fluctuation.

The receiving portion 172 is formed integrally with the main connecting portion 230 by a lower portion of the main connecting portion 230.

A sealing member 1 made of a foam material is provided between the rear edge of the blade holder 174 and the main connecting portion 230.
76 are provided. In addition, the cleaner blade 171
A rake sheet 177 is provided below the tip. The base of the rake sheet 177 is
, The leading edge of which is in slidable contact with the surface of the photoconductor 140 to prevent leakage of the toner T.

As shown in the plan view of FIG. 10, the both ends of the screw shaft 173a of the toner conveying screw 173 are rotatably supported by the side wall 172a of the receiving portion 172. A gear 173b is fixed to one end of the shaft 173a, and the gear 173b meshes with a gear 190 of the image carrier unit 101 via a reduction gear 173c. Therefore, when the image carrier unit 101 is rotationally driven, the toner conveying screw 173 is also rotationally driven, and the toner T in the receiving portion 172 is conveyed rightward in FIG. The transported toner T is stored in the waste toner bottle 1
Collected at 78.

A toner outlet 172b is opened at the bottom of the right end of the receiving portion 172, and a toner collecting port 178a of the waste toner bottle 178 is disposed below and below the toner outlet 172b. At the right end of the receiving portion 172, a shutter 172c slidable in the axial direction of the toner conveying screw 173 is provided. When the exterior cover (not shown) of the image forming apparatus is closed, the shutter 172c slides rightward in FIG. 10 to open the toner outlet 172b, and when the exterior cover is opened, the shutter 172c opens as shown in FIG.
, Slides to the left to close the toner outlet 172b. The waste toner bottle 178 is detachably attached to a case 80 (see FIG. 1) or a frame of the apparatus main body.

As shown in FIGS. 4, 8, and 11, both ends of the shaft 161 of the charging roller 160 are connected to the cartridge case 200 via bearing members 162, 162 (only one of which is shown in FIGS. 4 and 8). It is rotatable with respect to the side portions 210 and 220 and is supported so as to be slidable toward the center of the mounted photoconductor 140 (see FIG. 8). The side parts 210 and 220 are provided with cutout parts 212 and 222, and the opposite edge parts 212a and 212 are provided.
The guide members 162a, 162a formed on the upper and lower surfaces of the bearing member 162 are slidably fitted in the bearing members 162a, 222a, 222a.
0, 220 so as to be slidable. The notches 212 and 222 have spring receiving portions 212 b and 22.
2b are formed, and the spring receiving portion and the bearing member 16 are formed.
2, a compression coil spring 163 as an urging means is provided.
Are interposed respectively. Therefore, FIGS.
As shown in (2), when the image carrier unit 101 is incorporated in the cartridge case 200, the charging roller 160 comes into contact with the surface of the photoconductor 140 by the urging force of the spring 163.

As shown in FIGS. 4, 5, and 6, the fixed shaft 110 of the image carrier unit 101 has a protruding portion 112 protruding outwardly from the disk-shaped members 120 and 130.
The pins 113 and 113 are provided, and the side portions 210 and 220 of the cartridge case 200 are provided with pin receiving portions 213 and 223 for receiving the pins 113. The pins 113, 113 and the pin receiving portions 213,
223 constitutes a positioning means for determining the position of the fixed shaft 110 around the axis of the image carrier unit 101. The pin 113 may be fixed to the shaft 110 by being pressed into a through hole provided in the shaft 110, or may be configured integrally with the shaft 110. One end (right end in FIG. 4) 112a of the shaft 110 has a D-shaped cross section.

The side portions 210 and 220 are formed with slits 214 and 224 for guiding the shaft 110 when the image carrier unit 101 is assembled, and the pin receiving portions 213 and 223 are formed at the ends of the slits. It is formed integrally with the parts 210 and 220. The widths of the slits 214 and 224 are each slightly larger than the outer diameter of the shaft 110, and the starting ends of the slits 214 and 224 are formed to have an inclined wide width.

When the image carrier unit 101 is assembled, the protrusions 112, 112 of the shaft 110 are inserted into the pins 113 to the ends thereof in accordance with the slits 214, 224. Are in contact with the pin receiving portions 213 and 223, and the position around the fixed shaft 110 is determined. When inserting both the protruding portions 112 and 112 of the shaft 110 into the slits 214 and 224, the pin 113 abuts or slides on the outer surfaces of the side portions 210 and 220 to serve as a guide. Therefore, the pins 113 and 113, together with the side portions 210 and 220, also constitute a means for positioning the image carrier unit 101 in the axial direction.

The directions of the slits 214 and 224 are shown in FIG.
As shown in (2), the tip of the cleaner blade 171 is substantially in the same direction as the direction F in which the cleaner blade 171 is pressed against the photoconductor 140 of the image carrier unit 101. For this reason, the image carrier unit 1
When the image carrier unit 101 is mounted, it is possible to prevent the image carrier unit 101 from contacting the cleaner blade 171 from an undesired direction.
However, turning over and scratching are prevented. Note that this effect
This can be obtained if the directions of the slits 214 and 224 with respect to the pressing direction F are within a range of about ± 45 °.

As described above, the image carrier unit 10
1 is placed in the case body A,
Outside the side covers 250 and 26 shown in FIGS.
0 is attached. The side covers 250 and 260
A suitable fixing means, for example, a screw (not shown)
It is fixed to 10,220.

The side covers 250 and 260 have the shaft 11
Holes 251 and 261 are formed through the end of the zero. The hole 251 of the side cover 250 is D-shaped so as to fit with the D-shaped shaft end. Therefore, when the mounting direction of the image carrier unit 101 is not appropriate, the shaft end does not match the D-shaped hole 251, thereby preventing the mounting error of the image carrier unit 101.

Further, on the inner surfaces of the side covers 250 and 260, the pin 1 is located between the pin receiving portions 213 and 223.
Protrusions 252, 252, 262, 262 for fixing the pin 113, that is, the shaft 110, sandwiching the pin 13 are provided. Since the fixing structure is the same on the left and right, one side 2
Only 10 will be described. When the side cover 250 is attached to the side portion 210, as shown in FIG. 13, the pin 113 is sandwiched between the pin receiving portion 213 and the protruding pieces 252, 252, thereby fixing the pin 113. In addition, as shown in FIG.
When the pin receiving portion 213 and the pin 113 are sandwiched between the projecting piece 252a and the projecting piece 252 by further providing 52a and 252a, the pin 113 can be more securely fixed.

Further, rectangular holes 253, 263 are formed in the side covers 250, 260. Guide blocks 215 and 225 integrally formed outside the side portions 210 and 220 pass through the holes 253 and 263. The side cover 250 has an escape hole 254 for the toner conveying means.

A roller cover 270 is detachably mounted on the case body A. The mounted state is shown in FIG. As shown in FIG.
Is a slit-like window 271 for passing the exposure L1.
And a shielding plate 272 that shields between the static elimination light L2 and the charging roller 160 (charging unit).

The image carrier cartridge 100 assembled as described above is detachably mounted on the frame 82 of the image forming apparatus as shown in FIG.

A pair of the frame 82 and a lever 84 described later are provided in parallel with each other, but only one of them is shown in FIG.

A guide groove 83 is formed in the frame 82, and a lever 84 for detaching operation is provided.

The width of the guide groove 83 is the same as the outer diameter of the shaft 110 of the image carrier cartridge 100 and the thickness (height) h of the rear end 215a of the guide block 215. The starting end is formed to be wide and inclined.

The guide block 215 (and 22)
5) The height h of the rear end 215a is the same as the outer diameter of the shaft 110, but the height h 'of the front 215b is slightly smaller.

The lever 84 is rotatably attached to the frame 82 by a shaft 85, and includes a knob 84a,
Holding portion 84b of shaft 110 and contact portion 84c of shaft 110
And

When the lever 84 is rotated as indicated by the imaginary line, the holding portion 84b retreats from the movement path of the shaft 110 (projection 112) guided by the guide groove 83, and the contact portion 84c It faces near the end of the movement path.

Therefore, the image carrier cartridge 100
Is pushed in such a manner that the protrusions 112, 112 of the shaft 110 and the guide blocks 215, 225 are aligned with the guide grooves 83, and the protrusion 112 of the shaft 110 is
4c by pressing it against the lever 84c.
Rotates counterclockwise in the figure by the amount by which the contact portion 84c is pushed by the protrusion 112 of the shaft 110 (this state is not shown). Since the height h ′ of the front portion 215b of the guide block 215 (and 225) is slightly smaller than the width of the guide groove 83, the guide blocks 215 and 225 are easily inserted into the guide grooves 83. can do.

Thereafter, when the lever 84 is further rotated in the counterclockwise direction, as shown by the solid line in the figure, the shaft 110 is clamped and held between the end portion of the guide groove 83 and the holding portion 84b, and is fixed. Since the guide blocks 215 and 225 are fitted into the guide grooves 83, 83, the positioning of the image carrier cartridge 100 around the axis 110 is performed, and the mounting of the image carrier cartridge 100 on the frame 82 is completed. Guide block 215 (and 22)
5) The height h of the rear end 215a is formed to be the same as the width of the guide groove 83, and is fitted into the guide groove 83 without any gap, so that positioning is performed with high precision. When the lever 84 is rotated as shown by a solid line, the contact portion 84c is separated from the shaft 110.

When the image carrier cartridge 100 is removed, the lever 84 is rotated as shown by a virtual line.
Since the contact portion 84c acts to push the shaft 110, the image carrier cartridge 100 can be easily taken out.

A tension spring 86 is provided between the lever 84 and the frame 82.
The line of action of the force 6 is such that the lever 84 pivots over the shaft 85 that is the pivot center of the lever 84 when the lever 84 is pivoted as shown by the imaginary line and when the lever 84 is pivoted as shown by the solid line. Is configured.

Therefore, when the lever 84 is rotated as shown by the imaginary line, the action of the tension spring 86 causes
The lever 84 is held at a position indicated by a virtual line. On the other hand, when rotated as shown by the solid line, the lever 84 is held at the position shown by the solid line, and the image carrier cartridge 100 is securely held by the frame 82 by the action of the tension spring 86.

The image carrier cartridge 100 is mounted on the frame 82 from the left in FIG. 14 and FIG. 1, but the frame 82 and the case 80 of the image forming apparatus are taken along line BB in FIG. Since the image carrier cartridge 100 and the exposure unit 40 can be separated (for example, the exposure unit 40 is slidable to the left), the image carrier cartridge 100 can be easily attached and detached. be able to. FIG.
And the image carrier cartridge 100 as shown in FIG.
Knobs 231 and 231 for easy attachment and detachment
Are provided on the case body A.

When the above-described image carrier cartridge is incorporated in an image forming apparatus as shown in FIG. 1, the photosensitive member 140 and the intermediate transfer belt 36 come into contact with each other to form the primary transfer portion T1. When the drive gear 190 (not shown) of the image forming apparatus main body meshes with the drive gear 190, the photosensitive member 140 and the intermediate transfer belt 36 are driven to rotate in the direction of the arrow.

In this image forming apparatus, as shown in FIG. 6, a contact member such as a cleaner blade 171 which acts as a load on the photosensitive member 140 which is driven to rotate from one end (the left end in FIG. 6). Are arranged, so that the cleaning blade 1
A torsional force acts on the portion 140e between the contact portion 140d with the contact member such as 71 and the drive-side end.

Since the photosensitive member 140 has a thin cylindrical shape having flexibility, the photosensitive member 140 is formed by the twisting force.
0e may be deformed, and if it is deformed,
At the deformed portion 140e, the contact between the photosensitive member 140 and the contact member becomes inappropriate. Therefore, when the contact member is the cleaner blade 171, cleaning failure occurs, and when the contact member is the charging member 160, charging failure occurs. Further, since the deformation occurs over the entire circumference of the photoconductor 140 in the circumferential direction, the contact with another process member (not limited to a member serving as a load), for example, the developing roller 11 is also inappropriate. As a result, defective development may occur.

Accordingly, in this embodiment, the photosensitive member 14
The cleaning blade 171 (the charging roller 160 in this embodiment is driven by the rotation of the photosensitive member 140 so that the load is not large) and the photosensitive member 140 is a contact member that becomes a main load with respect to the rotation of zero. Friction coefficient μ1
The friction coefficient μ2 between the photoconductor 140 and the backup drum 150 is larger than that of the photoconductor 140 (that is, μ1 <μ2). Desirably, it is configured such that 3 × μ1 <μ2.

In the axial direction of the shaft 110, the backup drum 150 is longer than the contact member such as the cleaner blade 171.

According to the image forming apparatus described above, the following operation and effect can be obtained.

(A) The image carrier unit 101 of this image forming apparatus has a pair of circles in which both end portions 141 of a thin cylindrical image carrier (photoreceptor) 140 are rotatably mounted on a shaft 110. Since the plate-like members 120 and 130 are supported and fixed, when the disk-like members 120 or 130 are rotationally driven, the image carrier 140 is surely rotationally driven.

Further, both ends 141 of the image carrier 140 are
Since it is configured to be supported and fixed by the pair of disk-shaped members 120 and 130, it has excellent durability.

(B) The image carrier 140 is a thin cylindrical member having flexibility, and both ends 141 of the image carrier 140 are disc-shaped members 12.
Because it is a configuration supported by 0,130,
In the image carrier 140, a central portion 142 (see FIG. 6) that is not supported by the disk-shaped members 120 and 130 can be deformed inward.

Therefore, the portion 142a (see FIGS. 6 and 8) of the central portion 142 of the image carrier 140 which is not supported from the inside by the backup drum 150 can be used as a pseudo soft material. Therefore, even if the member to be brought into contact with the developing roller 11 is a hard roller or the like, a reliable and stable contact state can be obtained, and an image can be reliably formed on the image carrier 140 or Can be carried.

On the other hand, the cleaning member 171 as a contact member and the charging roller 160 are brought into contact with the outer peripheral surface of the image carrier 140. At the contact position, the image carrier 140 is not in contact. Since they are supported from the inside by the backup drum 150, these contact members can be reliably brought into contact.

That is, the cleaning member 171 and the charging roller 160 are reliably brought into contact with the image carrier 140, so that the toner remaining on the outer peripheral surface of the image carrier 140 can be reliably removed, and the toner can be reliably charged.

Moreover, if the backup drum 15
If the contact member is kept in contact with the image carrier 140 for a long time in a state where there is no zero, the image carrier 140 having a thin cylindrical shape may undergo creep deformation. According to this, such a fear is also eliminated.

(C) The image carrier unit 101 has the shaft 11
The two end portions 141 of the image carrier 140 are provided by a pair of disk-shaped members 120 and 130 rotatably attached to the image carrier 140.
Are supported and fixed, and the backup drum 150 is attached to the shaft 110 inside the image carrier 140 to form a unit.
The handling of the image carrier unit 101 itself becomes easy.

Further, the image carrier unit 101 is
Since it is held in the cartridge case 200, its handling is further facilitated.

(D) In this image forming apparatus, as described above, the contact member such as the cleaner blade 171 which acts as a load on the photosensitive member 140 which is driven to rotate from one end (the left end in FIG. 6) is used. Because of the arrangement, the cleaner blade 171 in the photoconductor 140 is provided.
A torsional force acts on a portion 140e between a contact portion 140d with a contact member such as the above and the drive-side end.

Since the photosensitive member 140 has a thin cylindrical shape having flexibility, the portion 140e may be deformed by the torsional force. If the deformation occurs, the deformed portion 140e is deformed. In this case, the contact between the photosensitive member 140 and the contact member becomes inappropriate. Therefore, when the contact member is the cleaner blade 171, a cleaning failure occurs, and the contact member becomes the charging member 16.
If it is 0, poor charging will occur. Further, since the deformation occurs over the entire circumference of the photoconductor 140 in the circumferential direction, the contact with another process member (not limited to a member serving as a load), for example, the developing roller 11 is also inappropriate. As a result, defective development may occur.

On the other hand, according to the image forming apparatus of this embodiment, the backup drum 150 is supported so as to be rotatable about an axis parallel to the shaft 110. As shown in FIG. 3, the outer peripheral surface 152 a of the backup drum 150 is
The power from the photoconductor 140 is transmitted by contact with the photoconductor 140 a, and as a result, the backup drum 150 rotates following the photoconductor 140. Therefore, the load on the photoconductor 140 can be reduced, and the driving torque of the photoconductor 140 can be reduced.

Therefore, the backup drum 150 serves as a transmitting member for transmitting the driving force acting from one end of the photosensitive member 140 to the photosensitive member 140 at the supporting portion for the photosensitive member 140.
The aforementioned torsional force is reduced, and as a result, the aforementioned deformation of the photoconductor 140 is suppressed, and image defects are less likely to occur.

Furthermore, the friction coefficient μ1 between the cleaner blade 171 and the photosensitive member 140, which are the main contact members, is smaller than the friction coefficient μ1.
Since the friction coefficient μ2 between the photoconductor 140 and the backup drum 150 is configured to be larger, the frictional force between the cleaner blade 171 and the photoconductor 140 is larger than the frictional force between the cleaner blade 171 and the photoconductor 140.
And the backup drum 150 has a greater frictional force. Therefore, for example, the torsional force received from the cleaner blade 171 when the photoconductor 140 is driven on one side is completely transmitted to the backup drum 150, and the torsional force does not act on the area of the photoconductor 140 where the backup drum 150 contacts. Thus, the torsional deformation of the photoconductor is suppressed. In other words, the driven rotation of the backup drum 150 with respect to the photoconductor 140 and the function as a power transmission member are reliably obtained.
0 is reliably suppressed, and image defects are more unlikely to occur.

As described above, according to the image forming apparatus of this embodiment, a reliable and stable contact state with the contact member can be obtained, the durability and handleability are excellent, and the image bearing member can be used. The effect of being able to drive reliably is obtained.

In addition, the above-described deformation of the image carrier is suppressed, and the effect of preventing image defects from occurring is obtained.

(E) As shown in FIG. 6, the backup drum 150 is longer than the abutting member such as the cleaner blade 171 in the axial direction of the shaft 110. That is, the portion 140e where deformation is likely to occur is supported by the backup drum 150, so that the deformation is further suppressed.

Therefore, the situation where the contact state between the photosensitive member 140 and the contact member becomes improper is more unlikely to occur, and as a result, an image defect is further less likely to occur.

The backup drum 150 has an outer diameter D1 slightly smaller than the inner diameter D2 of the image carrier 140, and is rotatably supported on the shaft 110 via an eccentric bearing member 155. Therefore, the following operation and effect can be further obtained.

(F) The backup drum 150 is
Since it is configured to be rotatably supported via the eccentric bearing members 154 and 155 with respect to 10, the structure is simple, and it is possible to easily assemble. Therefore, it can be produced with high accuracy.

(G) The backup drum 150 has an outer diameter D1 slightly smaller than the inner diameter D2 of the image carrier 140, and is rotatably supported on the shaft 110 via an eccentric bearing member 155. The image carrier 140 can be supported over a wide range from the inside at the contact position where the contact member contacts the image carrier 140 from the outside (see FIG. 8). Therefore, the function as the power transmission member described above can be obtained more favorably,
Image defects are more reliably prevented.

[0162]

<Regarding the Photoconductor Cartridge 100> Regarding the Photoconductor 140 (1) A nickel seamless tube manufactured by an electroforming method is used as the base 140 b of the photoconductor 140, and the thickness thereof is as follows.
It is about 40 μm.

If the thickness of the base material is too small, the rigidity (strength of maintaining the shape of the base material) becomes weak, resulting in poor cylindricity and poor contact with a contact member such as a developing roller. Therefore,
The thickness of the substrate is desirably 0.04 mm or more.

On the other hand, if the thickness of the base material is too large, it is difficult to obtain good flexibility, and the stress generated by the contact with the contact member also increases. In addition, since the electroforming time becomes longer, the manufacturing cost also increases.
Therefore, the thickness of the substrate is desirably 0.05 mm or less.

Therefore, in this embodiment, the thickness of the base material is
It is about 40 μm.

(2) The photosensitive layer 140c is an undercoat layer (UC
L), a charge generation layer (CGL), and a charge transport layer (CT
L), and the thickness of each layer is as follows.

The undercoat layer is about 1 to 2 μm, the charge generation layer is about 0.5 μm, and the charge transport layer is about 15 to 30 μm.

Since the photosensitive layer is worn by contact with a contact member such as the cleaner blade 171 or the like, if the thickness of the photosensitive layer is too thin, the life is shortened. Therefore, the thickness of the photosensitive layer is desirably 0.015 mm or more.

On the other hand, when the photosensitive layer is thick, the charge is easily dispersed, and high resolution cannot be obtained. In this embodiment, a resolution of 600 dpi or more can be obtained.
It is desirable that it is 25 mm or less.

Thus, in this embodiment, the thickness of the photosensitive layer is set as described above.

(3) The diameter (outer diameter) of the photosensitive member 140 is φ
It is about 85.5 mm.

The image forming apparatus shown in FIG. 1 is capable of forming an image on A3-sized paper.
Therefore, in order to continuously form an image on a continuously supplied sheet, the intermediate transfer belt is considered in consideration of the interval between the sheets (the distance between the trailing edge of the preceding sheet and the leading edge of the succeeding sheet). The diameter of the outer circumference of 36 is φ171m
m or more is required.

On the other hand, in order to reduce the relative positional error of the Y, C, M, and K toner images formed on the intermediate transfer belt 36 in the belt traveling direction and to loosen the tolerances of the components, the intermediate transfer It is desirable that the diameter of the belt 36 and the diameter of the photoconductor 140 be an integer ratio, and that the position of the image formed on the photoconductor 140 with respect to the photoconductor 140 be the same for each color.

On the other hand, the four developing means 10 (Y, C, M,
Although it is desirable that the diameter of the photoconductor 140 be φ60 mm or more in order to enable K) to be arranged around the photoconductor 140, it is preferable that the diameter of the photoconductor 140 be as small as possible in order to reduce the size of the apparatus. desirable.

Therefore, in this embodiment, the diameter (outer diameter) of the photosensitive member 140 is set to about φ5.5 mm.

However, the diameter of the photoreceptor 140 can be in the range of φ80 to 90 mm by reducing or increasing the interval between continuously supplied sheets.

(4) The length of the photosensitive member 140 in the axial direction is 4
It is about 10 ± 0.2 mm.

In order to prevent permanent deformation of the photosensitive member 140 which is bent by contact with the charging roller 160 and the like,
The distance between the supported portion of the photoconductor 140 and the end of the charging roller 160 or the distance between the end of the developing roller 11 and
mm is desirable.

Thus, in this embodiment, the length of the photosensitive member 140 is set to about 410 ± 0.3 mm.

The length of the charging roller 160 and the like will be described later.

(5) Cleaner blade 1 of photoconductor 140
The coefficient of friction with respect to 71 is set to 1.0 or less. Specifically, it is about 0.5 to 1.

If the friction coefficient exceeds 1.0, the photosensitive member 14
This is because the drive torque of 0 increases and the torsional force also increases.

(6) The cylindricity of the photoconductor 140 in the state where it is incorporated in the photoconductor unit 101 is set to 0.05 mm or less.

The reason for this is that the depth at which the developing roller 11 bites into the photosensitive member 140 is set to about 0.15 mm to obtain a stable contact state.

(7) The grounding structure of the photoconductor 140 is as follows.

In FIG. 6, the backup drum 150
Made of a conductive material (for example, aluminum)
The shaft 110 is also made of a conductive material (for example, stainless steel), and a conductive member 157 for electrically connecting the cylindrical member 152 and the shaft 110 to the inner surface of the side plate 151.
Is provided. The conducting member 157 is made of, for example, a stainless steel leaf spring whose both ends contact the cylindrical member 152 and the shaft 110.

An end of the shaft 110 is brought into contact with a conductive member 87 also made of a stainless steel leaf spring or the like. This conductive member 87 is attached to the frame of the image forming apparatus which is grounded.

Therefore, the photosensitive member 140 has an inner peripheral surface of the conductive substrate 140b → a cylindrical member 152 of the backup drum 150 → a conductive member 157 → a shaft 110 → a conductive member 8
7 → grounded via frame.

Regarding the shaft 110, the shaft 110 is constituted by a metal shaft. For example, it is constituted by a stainless steel shaft.

The diameter is about φ12 mm and the length is 490 mm
Degree.

Regarding the backup drum 150, the coefficient of friction between the backup drum 150 and the photosensitive member 140 is set to 1.0 or more. Specifically, it is set to about 1.5.

When the friction coefficient is 1.0 or less, the photosensitive member 1
This is because the follow rotation of the photosensitive member 140 decreases, and the torsional force acting on the photosensitive member 140 increases.

The side plate 151 of the backup drum 150 is made of a synthetic resin, and the cylindrical member 152 is made of an aluminum pipe.

The axial length of the backup drum is 3
It is about 75 mm.

It is desirable that the positional accuracy of the backup drum 150 in the radial direction be approximately ± 100 μm. Further, it is desirable that the positional accuracy in the circumferential direction (the rotation direction of the image carrier 140) be within ± 1 °.

The eccentric bush 154 is made of synthetic resin.

Regarding the Charging Roller 160 (1) The charging roller 160 is a two-layer rubber roller having a surface layer.

The reason why the surface layer is provided is to prevent bleed-out of a substance that attacks the photosensitive member 140. Also, this is for controlling the resistance value of the charging roller 160.

The layer on the center side is an ion conductive rubber (NBR) in which a metal salt (lithium perchlorate) is dispersed in urethane or nylon resin. This is to reduce the voltage and current dependence of the resistance value.

The surface layer is formed of SN on urethane or nylon resin.
A material in which O ₂ and carbon black are dispersed is used.

(2) The diameter of the charging roller 160 is φ14 m
m, and the diameter of the shaft 161 is about φ10 mm.

In order to prevent deformation of a shaft having a length of 371 mm, a diameter of about φ10 mm is required.

Therefore, in this embodiment, the diameter of the shaft 161 is about 10 mm, the rubber thickness is about 2 mm, and the diameter of the charging roller 160 is about 14 mm.

(3) The resistance value of the charging roller 160 is 1 × 1
0 ^{5 to} 5 × 10 ⁶ Ω.

If the resistance value is 1 × 10 ⁵ Ω or less, it becomes impossible to cope with pinholes, and if the resistance value is 5 × 10 ⁶ Ω or more, the charging ability is reduced.

(4) The voltage applied to the charging roller 160 is
Approximately -1 to 1.5 kV. This voltage is optimally controlled by the control unit 90 of the image forming apparatus main body.

(5) The driving method of the charging roller 160 is a method of being driven by the photosensitive member 140, that is, a method of being driven by the photosensitive member 140.

This is to prevent the photosensitive member 140 and the charging roller 160 from sliding relative to each other (sliding) to prevent the occurrence of uneven charging due to charge injection.

[0209] Another reason is that the structure can be made simple and inexpensive.

(6) The pressing force of the charging coil 160 against the photosensitive member 140 by the compression coil springs 163 and 163 is set to about 1.4 gf / mm.

[0211] If the pressing force is too large, the stress applied to the photoconductor 140 becomes too large. If the pressing force is too small, a stable contact state with the photoconductor 140 and follow-up cannot be obtained.

Therefore, in this embodiment, the pressing force is set to 1.4.
gf / mm.

(7) The electrode structure is as shown in FIG.
One end 161a of the shaft 161 is formed in a hemispherical shape, and a leaf spring 164 made of a conductive member (for example, stainless steel or phosphor bronze) is pressed against the end. The leaf spring 164 is attached to the side portion 220 of the cartridge case main body A, and has one end 164a.
To the electrode member 88 made of a leaf spring of the image forming apparatus main body.
Pressure contact. The voltage is applied to the charging roller 160 via the electrode member 88.

(8) The length of the charging roller 160 is 371 ±
It is about 0.5 mm.

[0215] For cleaning unit 170 (1) the length of the cleaning blade 171 is 370 ± 0.5
mm.

(2) The material of the blade 171 is urethane rubber.

This is because it has excellent wear resistance and is inexpensive.

(3) The hardness of the blade 171 is 60 °-
80 ° (JIS A).

[0219] If the photoconductor 140 is too hard, the photoreceptor 140 wears excessively. If it is too soft, the blade wears excessively.

(4) The thickness of the blade 171 is 2 to 3 mm
And the free length (the length of the portion not indicated by the blade holder 174) is about 8 to 10 mm.

(5) The used ridge roughness of the blade 171 is as follows:
Rmax is set to 10 μm or less.

This is for ensuring the cleaning property.

(6) The contact pressure of the blade 171 against the photosensitive member 140 is set to 20 to 40 g / cm.

[0224] If the contact pressure is too large, the photosensitive member 140 is easily worn by friction with the blade 171 and the life of the photosensitive member 140 is shortened. Also, the photoconductor 14
This is because the torsional force on the photoconductor 140 increases as the driving torque of 0 increases.

On the other hand, if the contact pressure is too small, the cleaning property is reduced, and it becomes difficult to prevent filming of the photosensitive member.

(7) The contact angle θ1 of the blade 171 with respect to the photosensitive member 140 (see FIG. 9; the photosensitive member 1 at the contact portion)
The angle between the tangent to 40 and the cleaner blade 171) is 15 to 30 °.

[0227] If the contact angle θ1 is too large, the cleaning performance is degraded, and in order to improve this, the contact pressure must be increased.

Conversely, if the contact angle θ1 is too small, the abdominal contact state is not achieved within the range of the positional accuracy of the blade 171. That is, it is prevented that the ridge line of the blade 171 does not reliably contact the photosensitive member 140. This is because the position accuracy of the blade must be strict.

(8) The angle θ2 of the rotation fulcrum position of the blade holder 174 (see FIG. 9).
(The angle formed by the line connecting the contact portion and the contact portion) is 30 to 40 °.

(9) The seal member 176 is made of a foam sheet.

(10) The rake sheet 177 is made of a PET film.

The thickness is about 100 μm, and the free length is 6.6 m
m, the amount of deflection is about 1 mm, and the contact angle with the photoconductor 140 is 0 °.

<Regarding Holding Force of Image Carrier Cartridge 100 See FIG. 14> The holding force of the image carrier cartridge 100 by the pair of tension springs 86 is
4 kgf on the side and 2-3 kgf on the opposite side.

The reason for increasing the holding force on the gear 190 side is as follows.
This is to prevent the image carrier cartridge 100 from coming off due to the reaction force received by the gear 190.

In addition, the above-mentioned spring force provides a click feeling at the time of an attaching / detaching operation, and enables a smooth attaching / detaching.

The embodiments and examples of the present invention have been described above. However, the present invention is not limited to the above-described embodiments or examples, and can be appropriately modified within the scope of the present invention. It is.

For example, in the above embodiment, the image carrier unit was described as a photosensitive unit, but the image carrier unit of the present invention is not limited to this, and may be configured as an intermediate transfer medium unit. In this case, the image carrier is a thin cylindrical intermediate transfer medium.

[0238]

According to any one of the first to third aspects of the present invention, a reliable and stable contact state with the contact member can be obtained, the durability and handleability are excellent, and the image bearing member can be used. The effect of being able to drive reliably is obtained.

In addition, the effect of suppressing the torsional deformation of the image carrier and suppressing the occurrence of image defects can be obtained.

Further, according to the image forming apparatus of the second aspect, the torsional deformation of the image carrier is further suppressed, and the image defect is more unlikely to occur.

According to the image forming apparatus of the third aspect, the structure is simple, can be easily assembled, can be manufactured with high accuracy, and the load on the image carrier can be reduced. The drive torque of the image carrier can be reduced, and the effect of the backup drum as a power transmission member can be obtained more favorably, so that image defects are less likely to occur.

[0242]

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is an enlarged partial cutaway view of an image carrier unit and its periphery.

FIG. 3 is an enlarged partial sectional view taken along the line III-III in FIG. 2;

FIG. 4 is an exploded perspective view of the image carrier cartridge.

FIG. 5 is a partially omitted exploded perspective view seen from another angle.

FIG. 6 is a cross-sectional view of the image carrier unit 101.

FIG. 7 is a partially enlarged view of FIG. 6;

FIG. 8 is a cross-sectional view of the image carrier cartridge 100.

FIG. 9 is a partially enlarged view of FIG. 8;

FIG. 10 is a plan view mainly showing a toner conveying screw 173.

11 is a plan view mainly showing a charging roller 160. FIG.

FIG. 12 is a partial cross-sectional view mainly showing a direction in which the image carrier unit 101 is incorporated into the main body A of the cartridge case 200.

FIG. 13 is a partial sectional view mainly showing a fixing structure of a pin 113;

FIG. 14 is a partially omitted side view showing a structure for attaching and detaching the image carrier cartridge 100 to and from the frame 82 of the image forming apparatus.

FIGS. 15A and 15B are explanatory diagrams of a conventional technique.

[Explanation of symbols]

 101 Image Carrier Unit 110 Axis 120, 130 Disk Member 140 Image Carrier (Photoconductor) 150 Backup Drum 154 Eccentric Bush (Eccentric Bearing Member) 155 Bearing (Eccentric Bearing Member) 160 Charging Roller (Contact Member) 171 Cleaner Blade (contact member) 190 Drive gear (rotation drive means)

Claims (3)

[Claims] 1. A shaft that does not rotate by itself, a pair of disk members rotatably attached to the shaft, and a disk member having both ends supported and fixed by the pair of disk members. A flexible thin-walled cylindrical image carrier that is rotationally driven together with the image carrier, and is mounted on the shaft so as to be rotatable about an axis parallel to the axis inside the image carrier, and An image carrier unit including a backup drum that supports the image carrier from the inside at the abutting position where the abutting member abutting from the outside and acting as a load on the rotation of the image carrier abuts And an image carrier rotation driving means provided at one end of the image carrier unit, wherein the image carrier and the backup drum are arranged to have a smaller friction coefficient than the contact member and the image carrier. Larger coefficient of friction The image forming apparatus characterized by being. 2. The image forming apparatus according to claim 1, wherein the backup drum is configured to be longer than the contact member in the axial direction of the shaft. 3. The image forming apparatus according to claim 2, wherein the backup drum has an outer diameter slightly smaller than an inner diameter of the image carrier, and is rotatably supported on the shaft via an eccentric bearing member. The image forming apparatus according to claim 1.