JPH10333527A - Image carrier unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image carrier unit capable of obtaining sure and stable contact states with abutting members and surely driving and excellent in durability and operability. SOLUTION: A thin cylindrical image carrier 140 having flexibility is supported by a pair of disk like members 120 and 130 rotatably attached to a shaft 110 not rotating by itself and fitted to the shaft 110 in the inside of the image carrier 140. A cleaning member 210, an electrifying roller 220 and a transfer roller 230 are brought into contact with the image carrier 140 from the outside. Backup members 151-153 for supporting the image carrier 140 from the inside are provided in the abutting positions and energized by an energizing means 160.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image carrier unit used in 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 The image forming apparatus includes a developing unit that forms a (toner image), and a transfer unit that transfers the toner image developed by the developing unit to a transfer medium such as paper.

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.

Further, as the charging means, the developing means, and the transfer means, there are known roller-shaped members each of which comes into contact with the surface of the photoreceptor.
Hard and soft rubber are known.

[0005] A hard photoconductor drum is used as the photoconductor,
In addition, if a hard roller is used as the roller to be brought into contact with the roller, there is naturally a limit in manufacturing the photosensitive drum and the hard roller with high accuracy, and an error always occurs. Have difficulty. If the two do not contact uniformly, there is a gap locally and uneven charging,
There is a problem that uneven development and uneven transfer occur, and the photosensitive drum and the hard roller are damaged by being pressed more than necessary.

Therefore, it is not usually practiced that both the photosensitive member and the roller that comes into contact with the photosensitive member are made of a hard material. When a hard photosensitive drum is used as the photosensitive member, the roller is made of a soft material. When a hard roller is used as a roller made of rubber, a flexible photoconductor belt is used as a photoconductor.

[0007] However, when the roller to be brought into contact with the surface of the photoreceptor is made of soft rubber, there are the following problems.

When a charging roller or the like to be brought into contact with the surface of the photoreceptor is formed of a rubber roller, conductive particles such as carbon are dispersed in order to impart conductivity to the roller. The rubber hardness changes due to unevenness and variation in the degree, and the hardness on the roller surface varies, so that there has been a problem that a good adhesion state to the photoreceptor cannot be obtained.

Conversely, when the dispersion amount of carbon is reduced in order to obtain a good adhesion state to the photoreceptor, there has been a problem that the conductivity is varied to cause uneven charging.

Further, if a plasticizer to which a plasticizer is added is used in order to enhance flexibility, the plasticizer may seep out to the surface depending on long-term use or use environment. However, there is a problem that the photoconductive material in the photoconductor is denatured by adhering to the surface of the photoconductor, or the surface of the photoconductor is peeled off by sticking the photoconductor to the roller.

Such a problem can be solved by using a hard roller as the roller and using a flexible photosensitive belt as the photosensitive member.

However, when a photoreceptor belt is used as the photoreceptor, at least two
The necessity of the book supporting rollers not only complicates the structure, but also increases the size of the apparatus.

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

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

FIGS. 10A and 10B show the photoconductor driving device, wherein FIG. 10A is a side view and FIG. 10B is a perspective view.

The photoconductor driving device has a photoconductor belt 20 formed as a cylindrical thin film sheet, and an outer diameter circumference shorter than the inner diameter circumference of the photoconductor 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. 10, 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 photoconductor driving device, the photoconductor belt 20 is driven by the pressing member 22 in a state of being partially adhered to the surface of the driving roller 21, and the pressing member 2 is driven.
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 device, 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 between the developing roller 26 and the developing roller 26 can be stably performed with a sufficient nip width and a very low pressure contact force even when the developing roller 26 is made of a hard material because the flexure 23 acts as an elastic body. Done.

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 size of the apparatus can be prevented.

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

[0023]

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 broken from the edge or may not be broken, but may cause a serious image defect.

The photoreceptor belt 20 must be handled as a single unit until the photoreceptor belt 20 is incorporated into the apparatus in a state 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 carrier unit which is excellent in image quality and can be driven reliably.

[0028]

According to another aspect of the present invention, there is provided an image carrier unit comprising: a shaft which does not rotate by itself; and a pair of disks which are rotatably mounted on the shaft. -Shaped member, a thin cylindrical image carrier having both ends supported and fixed by the pair of disc-shaped members and having flexibility rotating with the disc-shaped member, and the shaft inside the image carrier. A backup member that is attached and supports the image carrier from the inside at the contact position where the contact member contacts the image carrier from the outside, and attaches the backup member in the support direction. And a biasing means for biasing.

According to a second aspect of the present invention, in the image carrier unit of the first aspect, the contact member is a cleaning member for removing a developer remaining on an outer peripheral surface of the image carrier. It is characterized by the following.

According to a third aspect of the present invention, in the image carrier unit of the first or second aspect, the backup member is a rotatable roller.

[0031]

According to the image carrier unit of the first aspect, the following effects can be obtained. (A) Since both ends of the thin cylindrical image carrier are supported and fixed by a pair of disk-shaped members rotatably attached to 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 the disc-shaped members. The central portion, which is not supported by, is inwardly deformable.

Therefore, the portion of the central portion of the image carrier where the backup member is not provided can be used as a so-called pseudo soft material. Even so, a reliable and stable contact state can be obtained, and an image can be reliably formed on an image carrier or an image can be carried.

On the other hand, a contact member such as a so-called process member (a charging member, a cleaning member, etc.) is brought into contact with the outer peripheral surface of the image bearing member. Since the body is supported from the inside by the backup member, the contact member can be reliably brought into contact.

Furthermore, if the contact member is brought into contact with the image carrier without the backup member, the thin cylindrical image carrier may be creep-deformed. According to the carrier unit, such a fear is eliminated.

Further, since the backup member supports the image carrier from inside while being urged by the urging means, the positional accuracy between the image carrier and the backup member is improved.

(C) Both ends of the image carrier are supported and fixed by a pair of disc-shaped members rotatably attached to the shaft, and a backup member is attached to the shaft inside the image carrier. Since the unit is formed as a unit, the handling becomes easy.

As described above, according to the image carrier unit of the first aspect, it is possible to obtain a reliable and stable contact state with the contact member, and it is excellent in durability and handleability, and it is reliable. The effect of being able to drive is obtained.

According to the image carrier unit of the second aspect, in the image carrier unit of the first aspect, the contact member removes the developer remaining on the outer peripheral surface of the image carrier. Therefore, the developer (for example, toner) remaining on the outer peripheral surface of the image bearing member can be reliably removed by bringing the cleaning member into contact with the cleaning member.

According to the image carrier unit of the third aspect, in the image carrier unit of the first or second aspect, since the backup member is constituted by a rotatable roller, the load on the image carrier is reduced. Can be reduced, and the driving torque of the image carrier can be reduced.

[0042]

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

<First Embodiment> FIG. 1 is a front sectional view (corresponding to the II section in FIG. 3) and a view mainly showing an image carrier unit according to a first embodiment of the present invention. 2
FIG. 3 is a left side view, and FIG. 3 is a partial side view showing a state where the image carrier unit is incorporated in an image forming apparatus.

As shown in these figures, the image carrier unit 100 has a shaft 110 which does not rotate by itself,
A pair of disk-shaped members 120 and 130 rotatably attached to the shaft 110, and both ends are supported and fixed by the pair of disk-shaped members 120 and 130 and rotate together with the disk-shaped members 120 and 130. A thin cylindrical image carrier 140 having flexibility, and a cleaning member 2 attached to the shaft 110 inside the image carrier 140 and serving as a contact member against the image carrier 140 from outside.
10 (see FIG. 3), the first, second, and third supports the image carrier 140 from the inside at the contact position where the charging roller 220 (see FIG. 3) and the transfer roller 230 (see FIG. 3) contact. A first backup roller 151, a second backup roller 152, a third backup roller 153 as a third backup member, and an urging means 160 for urging these backup rollers in the supporting direction (radially outward). And

In this embodiment, the first, second, and third backup rollers 151, 152, and 153 are provided as backup members. However, at least one backup member is provided at a necessary position. It may be. In this case, it is desirable to provide the cleaning member 210 at the contact position where the cleaning member 210 contacts.

As shown in FIG. 1, the shaft 110 has a large-diameter portion 111 disposed inside the image carrier 140, and protrudes from both ends of the large-diameter portion 111, and has disk-like members 120 and 130.
And small-diameter portions 112 and 113 penetrating therethrough. Side plates 181 and 182 for attaching the image carrier unit 100 to a frame F (only a part is shown) of the image forming apparatus are attached to the small diameter portions 112 and 113. The positioning of these side plates 181 and 182 and the shaft 110 in the circumferential direction is performed by pins 183. Also,
A ring-shaped concave groove 112a is formed in one small-diameter portion 112. When the image carrier unit 100 is incorporated into the image forming apparatus, the concave groove 112a engages with the frame F of the image forming apparatus. Thereby, positioning with respect to the frame F is performed.

Each of the pair of disc-shaped members 120 and 130 is rotatably provided on the shaft 110 via a bearing 114. These pair of disk-shaped members 120, 130
The sliding of the bearing 110 in the axial direction of the shaft 110 is restricted by retaining rings 115 and 116. A compression coil spring 117 for preventing backlash is provided between the left bearing 114 and the side plate 182.

The pair of disk-shaped members 120 and 130 have short cylindrical support portions 121 and 131 formed on the inner surfaces thereof, and the support portions 121 and 131 form both end portions 141 of the image carrier 140. Supported. Image carrier 14
0 can be fixed to the support portions 121 and 131 by appropriate means, for example, by bonding or the like.
In this embodiment, the following fixing structure is employed.

FIG. 4 is a view showing the fixing structure, and FIG.
FIG. Since this fixing structure is symmetrical, the left disk-shaped member 130 will be described.
Corresponding members on the right side are indicated by their reference numbers in parentheses.

As shown in FIG. 1 and FIG. 4, this fixing structure comprises a ring-shaped member 133 (123) arranged inside the disc-shaped member 130 (120) and on the outer periphery of the support portion 131 (121). And this ring-shaped member 133 (1
23) and an elastic ring 134 (124) made of an elastic material such as rubber disposed between the support portion 131 (121).
, The ring-shaped member 133 (123) and the support portion 131
(121) ring-shaped slider 135 disposed between
(125) and the ring-shaped slider 135 (125).
And a screw 136 (126) for sliding the

As shown in FIG.
Is a cylindrical portion 133a and a flange 133b integrated therewith.
And a stopper portion 133c integrally formed in a ring shape inside at the tip of the cylindrical portion 133a,
The flange 133b is fixed to the disc-shaped member 130 by an appropriate fixing means (for example, a screw) not shown.

The elastic ring 134 has a stopper 133c.
In the state before the ring-shaped slider 135 is slid in the direction of the arrow X2 as described later, as shown by a solid line in FIG. A gap C is formed between the surface 131a. Therefore, in this state, the image carrier 1
The end 141 of the forty can be inserted into the gap C.

The ring-shaped slider 135 is provided with the elastic ring 1.
It is arranged between 34 and the disc-shaped member 130.

The screw 136 is screwed into the disk-shaped member 130, and the tip 136 a of the screw 136 can contact the ring-shaped slider 135. A plurality of screws 136 (six as shown in FIG. 2 in this embodiment) are provided at equal intervals in the circumferential direction.

Therefore, in such a structure, when the screw 136 is rotated, its tip 136a comes into contact with the ring-shaped slider 135 and slides in the direction of arrow X2.

When the ring-shaped slider 135 slides in the direction of the arrow X2, the ring-shaped tip surface 135a presses the elastic ring 134 between the ring-shaped slider 135 and the stopper 133c of the ring-shaped member 133.

The inner peripheral surface 13 of the pressed elastic ring 134
4a tends to bulge inward as indicated by the imaginary line in FIG. 4 (this state is conceptually drawn), but in fact, this bulge is caused by the support 131 and the image. As a result, the end 141 of the image carrier is sandwiched between the support 131 and the inner peripheral surface 134a of the elastic ring.

That is, according to this fixing structure, the screw 1
By rotating the ring-shaped slider 135 by rotating the ring 36, the inner peripheral surface 134 a of the swelling elastic ring 134 and the supporting portion 131 form the end portion 14 of the image carrier 140.
1 can be clamped and fixed to the support 131.

As shown in FIG. 1, the other disk-shaped member 12
0, a driving gear 122 is fixed to the outer surface thereof.

In this embodiment, the image carrier 140 is formed as a photosensitive member, and is formed by forming a photosensitive layer on the surface (outer peripheral surface) of a flexible base material. As the substrate, for example, a nickel seamless tube produced by an electroforming method can be used. The photosensitive layer can be formed by so-called OPC (organic photoreceptor) by dipping. Since the flexibility, that is, the flexibility of the photoconductor 140 can be determined by adjusting the thickness and the diameter of the base material, the flexibility can be appropriately set according to the image forming apparatus to be used. It is possible. For example, the thickness is appropriately set within the range of the substrate thickness of 20 to 200 μm and the substrate diameter of 10 to 300 mm. OPC is mainly composed of resin, and therefore is excellent in flexibility. However, in order to secure adhesion to the substrate and to take measures against laser beam interference, the OPC and the OPC are used.
It is desirable to form an undercoating layer between C and C. 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.

Backup rollers 151, 152, 15
3, 3 is attached to the shaft 110 via a pair of attachment plates 170, 170 and a biasing means 160, as shown in FIGS. Backup roller 15
Since the mounting structure of 1, 152 and 153 is basically the same, the backup roller 151 will be described as a representative.

Flanges 175 and 175 are fixed to both sides of the large diameter portion 111 of the shaft 110, and a mounting plate 170 is fixed to the flange 175.

As shown in FIG. 5, in the center of the mounting plate 170, the insertion hole 1 of the small diameter portion 112 or 113 of the shaft 110 is provided.
A small-diameter portion of the shaft is inserted through the insertion hole 171, and the mounting plate 170 is fixed to the flange 175 with screws (not shown) or the like. The mounting plate 170 has a mounting space 172 for the urging means 160.

The urging means 160 includes the backup roller 1
Bearing member 16 rotatably supporting the shaft end 151a of the shaft 51
1, 161 and the bearing members 161, 161
Compression springs 162, 16 for urging radially outward
2 is provided.

The guide groove 1 is provided on both sides of the bearing member 161.
61a and 161a are provided.
The side edges 172a, 172a forming the mounting space 172 of the mounting plate 170 are engaged with the shafts 61a, 161a as shown in FIG.
It is attached to the attachment plate 170 so as to be slidable in the radial direction of 0 (the direction of arrow Y in FIG. 6B).

The compression spring 162 is provided between the bearing member 161 and the cylindrical portion 176 of the flange 175.

The backup rollers 151 and 151 as described above
The image bearing members 152 and 153 are arranged inside the image carrier 140 so as to contract the compression spring 162, and in the arranged state, as shown in FIGS. The body 140 will be supported from inside.

The image carrier unit 1 as described above
As shown in FIG. 3, the image carrier (photoconductor) 140 is incorporated in the image forming apparatus, and the driving gear 122 engages with a driving gear (not shown) of the image forming apparatus main body. It is driven to rotate in the direction of arrow a.

In FIG. 3, reference numeral 220 denotes the above-described charging roller, L denotes a laser beam for selectively exposing the surface of the photoconductor 140, 300 (Y, M, C, K) denotes a developing roller, and 230 denotes the above-described transfer roller. 210 is the cleaning member described above.

The charging roller 220 comes into contact with the outer peripheral surface of the photoconductor 140 to uniformly charge the outer peripheral surface.

The laser beam L is emitted from an exposing means (not shown), and selectively exposes the surface of the photoconductor 140 to form an electrostatic latent image on the surface of the photoconductor 140.

Each developing roller 300 (Y, M, C, K)
Are configured to be able to contact and separate from the photoconductor 140, respectively, and only one of the developing rollers is
Can come into contact with Developing roller 300
(Y) is yellow toner, 300 (M) is magenta toner, 300 (C) is cyan toner, 300 (K)
Supplies black toner onto the photoconductor 140. These developing rollers are constituted by a metal roller having a roughened surface or a hard resin roller.

An intermediate transfer belt 400 is circulated between the transfer roller 230 and the photosensitive member 140, and a secondary transfer roller (not shown) is arranged opposite to the intermediate transfer belt 400. ing. While the intermediate transfer belt 400 is driven to circulate, the transfer roller 230
Between the (primary transfer roller) and the photosensitive member 140, the toner image on the photosensitive member 140 is transferred onto the intermediate transfer belt 400, and the toner image transferred onto the intermediate transfer belt 400 is transferred to the secondary transfer roller. The image is transferred to a recording medium such as a sheet supplied between them.

The cleaning member 210 is constituted by a cleaning blade. The cleaning blade 210 and the charging roller 220
Built in. The sub case 240 can be combined with the image carrier unit 100 using the above-described side plates 181 and 182 (see FIG. 1) to form a single unit.

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

(I) When a print command signal (image forming signal) is input from a not-shown host computer (such as a personal computer), the photosensitive member 140 and the intermediate transfer belt 400 are driven to rotate.

(Ii) The outer peripheral surface of the photosensitive member 140 is uniformly charged by the charging roller 220.

(Iii) The outer peripheral surface of the uniformly charged photoreceptor 140 is selectively exposed L in accordance with the image information of the first color (for example, yellow) by an exposing means (not shown). A latent image is formed.

(Iv) Only the developing roller 300Y for the first color (for example, yellow) contacts the photosensitive member 140,
As a result, the electrostatic latent image is developed, and a first color (for example, yellow) toner image is formed on the photoconductor 140.

(V) The toner image formed on the photoconductor 140 is transferred onto the intermediate transfer belt 400 at the primary transfer section, that is, between the photoconductor 140 and the primary transfer roller 230. At this time, the secondary transfer roller is separated from the intermediate transfer belt 400.

(Vi) After the toner remaining on the photosensitive member 140 is removed by the cleaning member 210,
The photoconductor 140 is neutralized by a neutralization unit (not shown).

(Vii) The above operations (ii) to (vi) are repeated as necessary. That is, the second color, the third color, the fourth color,
Are repeated on the intermediate transfer belt 400 to form a toner image corresponding to the content of the print command signal.

(Viii) At a predetermined timing, a recording medium such as paper is supplied to a secondary transfer portion (a contact portion between the intermediate transfer belt 400 and the secondary transfer roller), and the intermediate transfer belt 4
The toner image (basically, a full-color image) is transferred onto the recording medium.

According to the image carrier unit 100 as described above, the following operational effects can be obtained.

(A) Since both ends 141 of the thin cylindrical image carrier 140 are supported and fixed by a pair of disk members 120 and 130 rotatably attached to the shaft 110, the disk is When the members 120 and 130 are driven to rotate, the image carrier 140 is reliably driven to rotate.

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 flexible thin-walled cylinder, 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. 1) that is not supported by the disk-shaped members 120 and 130 can be deformed inward.

Accordingly, of the central portion 142 of the image carrier 140, the backup members 151, 152, 1
Since the portion without 53 can be used as a so-called pseudo soft material, even if the member to be brought into contact therewith is a hard roller such as the developing roller 300, a reliable and stable contact state is obtained. Can be obtained, and an image can be reliably formed on the image carrier 140 or the image can be carried.

On the other hand, the cleaning member 210 as a contact member, the charging roller 220 and the transfer roller 230 are brought into contact with the outer peripheral surface of the image carrier 140. Since the carrier 140 is supported from the inside by the backup members 151, 152, 153, these contact members can be reliably brought into contact.

That is, the cleaning member 210 and the charging roller 220 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. . Also, at the transfer position, the image carrier 140 can be reliably brought into contact with the intermediate transfer belt 400 at the transfer roller 230 portion.

Moreover, if these backup members 1
If the cleaning member 210 or the like is brought into contact with the image carrier 140 without the 51 or the like, the image carrier 140 having a thin cylindrical shape may undergo creep deformation. According to this, such a fear is also eliminated.

Further, the backup member 151 and the like are urged by the urging means 160 to keep the image carrier 140
Is supported from the inside, so that the positional accuracy between the image carrier 140 and the backup member 151 is improved.

(C) Both ends 141 of the image carrier 140 are supported and fixed by a pair of disk-shaped members 120 and 130 rotatably attached to the shaft 110. Backup member 1
Since the unit 51 and the like are unitized by being attached to the shaft 110, handling becomes easy.

As described above, according to the image carrier unit 100 of this embodiment, it is possible to obtain a reliable and stable contact state with the abutting member, and it is excellent in durability and handleability and surely. The effect of being able to drive is obtained.

(D) Since the backup members 151, 152 and 153 are constituted by rotatable rollers, the image carrier 140
, The driving torque of the image carrier 140 can be reduced.

<Second Embodiment> FIG. 7 is a front sectional view (corresponding to a II section in FIG. 3) mainly showing an image carrier unit according to a second embodiment of the present invention. . In this figure, parts that are the same as those shown in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted.

The difference between the second embodiment and the first embodiment is that the backup rollers 151 and
Shaft ends 151 of 152 and 153 (only 151 is shown in the figure)
a, 151 a are provided with positioning rollers 163, 163.
Inner peripheral surfaces 121b, 13 of support portions 121, 131 of 130
1b, the backup roller 1
This is in that the positioning of 51, 152, and 153 is performed, and the other points remain unchanged.

According to such a configuration, the above (a)
(B) In addition to the effects of (c) and (d), the following effects (e) are further obtained.

(E) The rollers 163 and 163 are mounted on the inner peripheral surface 12 of the support portions 121 and 131 of the disk-shaped members 120 and 130.
1b, 131b, the backup rollers 151, 152, 153 are positioned.
That is, the urging force of the compression spring 162 is applied to the support portions 121, 1
31, the image carrier 14
It is possible to prevent unnecessary force from acting on zero.
Therefore, abrasion of the inner surface of the image carrier 140 can be reduced. Further, it is not necessary to increase the fixing strength of the image carrier 140 to the support portions 121 and 131, and the cost can be reduced.

<Third Embodiment> FIG. 8 is a front sectional view (corresponding to the II section in FIG. 3) mainly showing an image carrier unit according to a third embodiment of the present invention. . In this figure, parts that are the same as those shown in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted.

The difference between the third embodiment and the first embodiment is that the disc-like members 120 'and 130' are different from the first embodiment.
Are relatively long in the axial direction of the support portions 121 ', 131', and backup rollers 151, 152, 153 (151 in FIG.
(Shown only) are brought into contact with each other via the image carrier 140, so that the backup rollers 151, 15
2,153.

Along with this, a ring-shaped member 133 '(123'), an elastic ring 134 (124) and a ring for fixing both ends 141 of the image carrier 140 to the supporting parts 121 'and 131'. Slider 135 (1
25) is disposed inside the support portions 121 ′ and 131 ′.

Therefore, in this embodiment,
The flange 133'b of the ring-shaped member 133 'is inward,
The stopper 133'c is formed on the outside, and the screw 1
When the ring-shaped slider 135 is slid by rotating the ring 36, the outer peripheral surface 134b of the elastic ring 134 swells outward, and an image is formed between the outer peripheral surface 134b and the inner peripheral surface 131'b of the support portion 131 '. The end 141 of the carrier 140 is clamped and fixed.

In FIG. 8, reference numeral 123d denotes a ring-shaped member 123 '(133') which is a disc-shaped member 120 '(13').
This is a screw hole for a screw to be fixed to 0 ′).

According to such a configuration, the above-mentioned (a)
In addition to the effects of (b), (c), (d), and (e), the following effects (f) and (g) are obtained.

(F) Backup rollers 151 and 15
2, 153 are support portions 1 of the disc-shaped members 120 ', 130'.
Since the image carrier 140 is positioned by the inner peripheral surfaces 121'b and 131'b of the image bearing members 21 'and 131' and the image carrier 140 is also positioned by the inner peripheral surfaces, the backup rollers 151, 152 and 153 and the image carrier are consequently obtained. The positioning accuracy with respect to 140 is further improved.

(G) Outer peripheral surface 134b of elastic ring 134
The image carrier 140 is fixed by bulging outward, so that it is possible to relatively easily prevent a situation such as wrinkling at the end of the image carrier 140 at the time of fixing.

[0108]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The positional accuracy of the backup member in the radial direction is as follows.
It is desirable to set it to about ± 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 charging roller 22 with respect to the image carrier 140
0, the contact amount of the developing roller 310 and the transfer roller 230 (the concave amount of the image carrier 140) is desirably 0.5 mm or less.

Although the embodiments and examples of the present invention have been described above, the present invention is not limited to the above embodiments, and can be appropriately modified and implemented within the scope of the present invention.

For example, the structure of the biasing means can be appropriately adopted.
As shown in FIG. 9, the mounting space 172 'of the mounting plate 170'.
The bearing member 161 is slidably attached to the lever 177, and the lever 177 is swingably attached to the shaft 177a.
One end 177b is connected to the bearing member 161 and the other end 177b is connected thereto.
A tension spring 179 is provided between the backing roller 151, 152, 1.
53 may be biased radially outward.

In the above embodiment, the image carrier unit is described as a photoreceptor unit. However, 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.

[0113]

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

In addition, there is no fear that the thin cylindrical image carrier is creeped, and the positional accuracy between the image carrier and the backup member is improved.

Further, according to the image carrier unit of the present invention, the developer remaining on the outer peripheral surface of the image carrier can be reliably removed by reliably bringing the cleaning member into contact.

According to the image carrier unit of the third aspect, the driving torque of the image carrier can be reduced.

[0117]

[Brief description of the drawings]

FIG. 1 is a front sectional view mainly showing a first embodiment of an image carrier unit according to the present invention (a view corresponding to a II section in FIG. 3).

FIG. 2 is a left side view of the image carrier unit.

FIG. 3 is a partial side view showing a state where the image carrier unit is incorporated in an image forming apparatus.

FIG. 4 is a diagram showing a fixing structure of an end portion of the image carrier, and is a partially enlarged view of FIG. 1;

FIG. 5 is a view showing a mounting structure of a backup roller;
(A) is an exploded partial front view, (b) is a side view.

FIG. 6 is a view showing a mounting structure of a backup roller;
(A) is a cross-sectional view (a-a cross-sectional view in FIG.
(B) is a partial side view.

FIG. 7 is a front cross-sectional view (corresponding to the II section in FIG. 3) mainly showing the second embodiment of the image carrier unit according to the present invention;

FIG. 8 is a front sectional view (corresponding to a II section in FIG. 3) mainly showing an image carrier unit according to a third embodiment of the present invention;

FIG. 9 is a side view showing a modification of the urging means.

FIGS. 10A and 10B are explanatory diagrams of a conventional technique.

[Explanation of symbols]

REFERENCE SIGNS LIST 100 image carrier unit 110 shaft 120 disc member 130 disc member 140 image carrier 151 to 153 backup roller (backup member) 160 urging means 210 cleaning member 300 developing roller

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 thin cylindrical image carrier having flexibility that rotates together with the image carrier, mounted on the shaft inside the image carrier, and a contact member abutting against the image carrier from outside. An image carrier unit comprising: a backup member that supports the image carrier from the inside at a contact position; and a biasing unit that biases the backup member in the support direction. 2. The image carrier unit according to claim 1, wherein said contact member is a cleaning member for removing a developer remaining on an outer peripheral surface of said image carrier. 3. The image carrier unit according to claim 1, wherein the backup member is a rotatable roller.