JPH10333499A - Photoreceptor unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoreceptor unit where a sure and stable abutting state with a hard developing roller is obtained and also which is surely driven. SOLUTION: A thin cylindrical photoreceptor 140 having flexibility is supported by a pair of disk-like members rotatably attached to a shaft 110 that does not rotate by itself, and a backup member 190 attached at the shaft 110 at the inside of the photoreceptor and constituted of an elastic body supporting the photoreceptor 140 from the inside near an abutting position where a developing roller 300 abuts on the photoreceptor 140 from outside is provided. The backup member 190 is biased by a biasing means 160. The positioning part of the backup member is provided at the disk-like member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoreceptor unit used in an image forming apparatus such as a printer, a facsimile, a copying machine, etc. 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.

FIG. 8 is a diagram showing the photoconductor driving device.
(A) is a side view, (b) 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. 8, reference numeral 24 denotes a charger, 25 denotes an exposure device, 26 denotes a developing roller, 27 denotes a transfer charger, and 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 of the developing roller 26 is performed with a sufficient nip width and a very low pressure even when the developing roller 26 is made of a hard material because the flexure 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 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 developing roller 26 is brought into contact with the bending portion 23 where the pressing member 22 is not provided, so that the driving roller 21 and other vibration sources contact the developing roller 26. In the contact portion, there is a problem that the photoreceptor belt 20 vibrates, particularly in the radial direction. When the photoreceptor belt 20 vibrates,
The state of contact with the developing roller 26 becomes unstable, and jitter and density unevenness occur in the formed image.

Further, the above-mentioned conventional apparatus comprises a photosensitive belt 2
Since the photoreceptor belt 20 is not necessarily driven reliably, there is a problem that the photoreceptor belt 20 is not necessarily driven.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to obtain a reliable and stable contact state with a hard developing roller and to drive it reliably. It is an object of the present invention to provide a photosensitive unit which can be used.

[0026]

In order to achieve the above object, a photoreceptor unit according to claim 1 has a shaft that does not rotate by itself, and a pair of disk-shaped members rotatably mounted on the shaft. A member, a thin-walled cylindrical photosensitive member having flexibility, both ends of which are supported and fixed by the pair of disk-shaped members and rotating together with the disk-shaped member, and attached to the shaft inside the photosensitive member; A photoreceptor unit comprising: a backup member made of an elastic body that supports the photoreceptor from the inside near a contact position where the developing roller contacts the photoreceptor from the outside.

According to a second aspect of the present invention, in the photoconductor unit of the first aspect, the developing roller has a plurality of contact positions, and the backup member is disposed between the contact positions. It is characterized by being.

According to a third aspect of the present invention, in the photoreceptor unit according to the first or second aspect, an urging means for urging the backup member in the supporting direction is provided on the disc-shaped member. And a positioning portion for positioning the backup member in the supporting direction.

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

[0030]

According to the photoconductor unit of the first aspect,
The following operation and effect can be obtained. (A) Since both ends of the thin cylindrical photoreceptor are supported and fixed by a pair of disc-shaped members rotatably attached to a shaft, when the disc-shaped member is driven to rotate, the photosensitive The body is reliably driven to rotate.

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

(B) The photoconductor is a flexible thin-walled cylindrical shape and both ends thereof are supported by the disc-shaped members, so that the photoconductor is supported by the disc-shaped members. The central portion that is not deformed can be deformed inward.

Therefore, the central portion of the photoreceptor can be used as a pseudo soft material, so to speak.
Even if the member to be brought into contact with this is a hard developing roller or the like, it can be reliably brought into contact.

In the vicinity of the contact position where the developing roller comes into contact with the photoreceptor from the outside, the photoreceptor is supported from the inside by the backup member made of an elastic material. Is suppressed, and a stable contact state with the developing roller is obtained. As a result, the occurrence of jitter and density unevenness is suppressed.

When the photosensitive member is supported from the inside by the backup member made of an elastic material, it is conceivable to dispose the backup member at a position where the developing roller comes into contact with the photosensitive member. Is not properly arranged parallel to the axis of the photoconductor, or the softness (hardness) of the backup member is not uniform, the contact force between the developing roller and the photoconductor becomes uneven. Therefore, image unevenness may occur.

On the other hand, according to the photoconductor unit of the first aspect, the backup member made of the elastic body is
Since the photoconductor and the developing roller are arranged not close to the contact position but also close to the photoconductor and the developing roller, the backup member is arranged correctly parallel to the axis of the photoconductor. And the backing member has a non-uniform softness (hardness). Therefore, the contact force between the developing roller and the photoconductor is low at the contact position between the photoconductor and the developing roller. It is easy to be uniform.

Therefore, according to the photoreceptor unit of the first aspect, image unevenness is more unlikely to occur.

As described above, according to the photoreceptor unit of the first aspect, it is possible to obtain a reliable and stable contact state with the hard developing roller, and it is possible to obtain an effect that the drive can be reliably performed. .

According to the photoreceptor unit of the second aspect,
2. In a case where the photosensitive member unit according to claim 1 has a plurality of contact positions of the developing roller, the backup member is disposed between the contact positions, so that the backup member is disposed at the contact position. Compared with the case, the number of backup members can be reduced by one.

According to the photoreceptor unit of the third aspect,
3. The photoconductor unit according to claim 1, wherein a biasing unit that biases the backup member in the support direction is provided on the disc-shaped member, and the backup member is positioned in the support direction. 4. Since the positioning portion is provided, the positional accuracy between the photoconductor and the backup member is improved.

That is, the disc-shaped member is provided with a positioning portion for positioning the backup member in the supporting direction, and the urging force of the urging means is received by the positioning portion. Unnecessary force is prevented from acting.

Therefore, according to the photoreceptor unit of the third aspect, the driving torque of the photoreceptor can be reduced while suppressing the vibration of the photoreceptor.

According to the photoreceptor unit of the fourth aspect,
4. The photoconductor unit according to claim 1, wherein the backup member is configured by a rotatable roller, so that a smooth rotation state of the photoconductor can be obtained and a load on the photoconductor can be reduced. Can be smaller.

Therefore, according to the photoconductor unit of the fourth aspect, the driving torque of the photoconductor can be further reduced while suppressing the vibration of the photoconductor.

[0045]

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

FIG. 1 is a front sectional view (II in FIG. 3) mainly showing one embodiment of the photoreceptor unit according to the present invention.
FIG. 2 is a left side view, and FIG. 3 is a partial side view showing a state in which the photoconductor unit is incorporated in an image forming apparatus.

As shown in these figures, the photoreceptor unit 100 has a shaft 110 which does not rotate by itself, a pair of disc-shaped members 120 and 130 which are rotatably mounted on the shaft 110, and These pair of disc-shaped members 1
A flexible thin-walled photosensitive member 140 having both ends supported and fixed by the disk members 20 and 130 and rotating together with the disk-shaped members 120 and 130. The photosensitive member 140 is attached to the shaft 110 inside the photosensitive member 140. A backup roller 1 serving as a backup member for supporting the photosensitive member 140 from the inside near the contact position where the developing roller 300 (see FIG. 3) contacts the body 140 from the outside.
90.

In this embodiment, as shown in FIG.
Four developing rollers 300 (Y,
M, C, K), and the backup roller 1
Three 90s are arranged between the contact positions 301 of the developing roller 300. Each developing roller 300 is configured to be able to contact and separate from the photoconductor 140 as described later.

Further, the photoconductor unit 1 of this embodiment
00 includes backup rollers 151, 152 and 153 different from the backup roller 190. These backup rollers 151, 152, and 153 correspond to the cleaning member 210 (see FIG. 3), the charging roller 220 (see FIG. 3), and the transfer roller 230 (see FIG. 3) that contact the photoconductor 140 from outside. This is for supporting the photoconductor 140 from inside at the contact position.

Further, in the photosensitive member unit 100 of this embodiment, the urging means 1 for urging the backup rollers 190, 151 and the like in the supporting direction (radially outward).
60, and positioning portions 121b and 131b provided on the disk-shaped members 120 and 130 for positioning the backup roller in the supporting direction.

As shown in FIG. 1, the shaft 110 is
40, a large-diameter portion 111 disposed inside the
11 are provided with small-diameter portions 112 and 113 penetrating through the disc-shaped members 120 and 130. Side plates 181 and 182 for attaching the photoconductor 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. A ring-shaped concave groove 112a is formed in one of the small-diameter portions 112. When the photoconductor unit 100 is incorporated into the image forming apparatus, the concave groove 112a is engaged with the frame F of the image forming apparatus. By doing so, positioning with respect to the frame F is performed.

Each of the pair of disk-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.

A short cylindrical supporting portion 121, 131 is formed on the inner surface of each of the pair of disk-shaped members 120, 130, and the photosensitive member 1 is formed by the supporting portions 121, 131.
40 are supported at both ends 141. Both end portions 141 of the photoconductor 140 can be fixed to the support portions 121 and 131 by an appropriate means, for example, adhesion 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 FIGS. 1 and 4, the fixing structure is such that a ring-shaped member 133 (123) disposed inside the disk-shaped member 130 (120) and on the outer peripheral side 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. 4, the ring 133
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 photoconductor 14
0 end 141 can be inserted into 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.

Accordingly, in such a structure, when the screw 136 is rotated, the tip 136a of the screw 136 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 itself 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 phantom line in FIG. 4 (this state is conceptually drawn), but in fact, this bulge is caused by the support 131 and the photosensitive member. The end 141 of the photoconductor is blocked by the end 141 of the body 140. As a result, the end 141 of the photoconductor is pressed 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 (125) by rotating the ring 36, the elastic ring 13
4 (124) between the inner peripheral surface 134a and the support portion 131 to press the end 141 of the photoreceptor 140 and press the end portion 141 to the support portion 131.
(121).

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

The photosensitive member 140 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 light interference, the OPC and the OPC are used.
It is desirable to form an undercoat layer between the substrate and the PC. 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 is the cleaning member 210 (FIG. 3) as described above.
Charging roller 220 (see FIG. 3), transfer roller 2
30 (see FIG. 3) at its contact position.
Is used to support the photoconductor 140 from inside, and is used to prevent creep deformation of the photoconductor 140 as described later. Therefore, a material that can prevent the photoconductor 140 from deforming inward can be used. For example, it is made of metal, synthetic resin, hard rubber, or the like.

On the other hand, as described above, the backup roller 190 as a backup member is
0 (see FIG. 3) is for supporting the photosensitive member 140 from the inside in the vicinity of the contact position where the photosensitive member 140 is in contact with the photosensitive member 140 and suppressing the vibration of the photosensitive member 140.
Even when 00 is a hard roller, it is necessary to prevent the photosensitive member 140 from being deformed inward near the contact position thereof. Therefore, an elastic body that is easily deformed, such as a foamed elastic body (for example, a sponge). ) Etc.

Each backup roller has a metal shaft.

Backup rollers 151, 152, 15
3, 3 and 190 are a pair of mounting plates 170, 170 and the urging means 1 as shown in FIGS.
It is attached to the shaft 110 via 60. These backup rollers 151, 152, 153, and 19
Since the mounting structure of No. 0 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 (see FIG. 5) 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.

As shown in FIGS. 1 and 4, positioning rollers 163 and 163 are provided at the shaft end 151a of the backup roller 151.
3, 163 are disk-shaped members 120,
Inner peripheral surfaces 121b, 13 of support portions 121, 131 of 130
1b, the backup roller 15
Positioning 1 is performed.

The backup rollers 151 and 151 as described above
152, 153, and 190 are the compression springs 162
Is arranged inside the photoconductor 140 so as to contract,
In the arranged state, the biasing force of the compression spring 162 is applied to the inner peripheral surfaces 121 of the support portions 121 and 131 forming the positioning portion.
The photoreceptor 140 is supported from the inside in the state received by b and 131b.

Then, the photosensitive unit 10 as described above
0 is incorporated in the image forming apparatus as shown in FIG.
When a driving gear (not shown) of the image forming apparatus main body meshes with the driving gear 122, the photosensitive member 140 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 transfer roller described above. 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 exposure 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 driven to circulate between the transfer roller 230 and the photosensitive member 140. A secondary transfer roller (not shown) is disposed opposite 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 photoreceptor 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 host computer (personal computer or the like) not shown, 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 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 photoconductor unit 100 described above, the following operation and effect can be obtained.

(A) Both ends 141 of the thin-walled cylindrical photoconductor 140 are supported and fixed by a pair of disk-shaped members 120 and 130 rotatably mounted on the shaft 110. When the members 120 and 130 are rotationally driven, the photoconductor 140 is surely rotationally driven.

Further, since both ends 141 of the photosensitive member 140 are supported and fixed by the pair of disk-shaped members 120 and 130, the durability is excellent.

(B) The photoreceptor 140 is a thin cylindrical member having flexibility, and both ends 141 thereof are
Because it is a configuration supported by 0,130,
In the photoconductor 140, a central portion 142 (see FIG. 1) that is not supported by the disk-shaped members 120 and 130 can be deformed inward.

Therefore, of the central portion 142 of the photosensitive member 140, the backup rollers 151, 152, 1
Since the portion without 53 can be used as a so-called pseudo soft material, a reliable contact state can be obtained even if the member to be brought into contact with the portion is a hard roller such as the developing roller 300 or the like. And the photoreceptor 1
An image can be formed on or carry the image.

In the vicinity of the contact position 301 where the developing roller 300 comes into contact with the photosensitive member 140 from the outside, a backup member 190 made of an elastic material is provided.
Because the photoconductor 140 is supported from the inside by
Vibration of the photoconductor 140 is suppressed, and a stable contact state with the developing roller 300 is obtained. As a result, occurrence of jitter and density unevenness is suppressed.

The backup member 1 made of an elastic material
In supporting the photoconductor 140 from inside by 90,
It is conceivable that the backup member 190 is disposed at the contact position 301 of the developing roller 300. However, in such a configuration, the backup member 190 is
Not aligned correctly with the axis of
If the softness (hardness) of the backup member 190 is non-uniform, the contact force between the developing roller 300 and the photoconductor 140 becomes non-uniform, which may cause image unevenness.

On the other hand, according to the photoconductor unit 100 of this embodiment, the backup member 190 made of an elastic material is disposed not at the contact position 301 between the photoconductor 140 and the developing roller 300 but near it. Therefore, regarding the contact position 301 between the photoconductor 140 and the developing roller 300, the case where the backup member 190 is not correctly arranged parallel to the axis of the photoconductor 140, or the softness (hardness) of the backup member 190 ) Is not easily affected, and therefore, at the contact position 301 between the photosensitive member 140 and the developing roller 300, the developing roller 3
00 and the photoconductor 140 are likely to have a uniform contact force.

Therefore, according to the photoreceptor unit 100, image unevenness is more unlikely to occur.

As described above, according to the photoreceptor unit 100 of this embodiment, it is possible to obtain a reliable and stable contact state with the hard developing roller 300 and to drive the photoreceptor unit reliably. can get.

Further, (c) a plurality of contact positions 301 of the developing roller 300
In contrast, since the backup member 190 is arranged between the contact positions 301, the backup member 1
The number of backup members 190 can be reduced by one as compared to the case where 90 is disposed at the contact position 301.

(D) The urging means 160 for urging the backup member 190 in the supporting direction, and the disk-shaped member 1
20, 130, and positioning portions 121 b, which position the backup member 190 in the supporting direction.
131b, the positional accuracy between the photoconductor 140 and the backup member 190 is improved.

That is, the disk-shaped members 120, 130 are provided with positioning portions 121b, 131b for positioning the backup member 190 in the supporting direction, and the urging force of the urging means 160 is applied to the positioning portions 121.
b, 131b, it is possible to prevent unnecessary force from acting on the photoconductor 140.

Therefore, according to the photoconductor unit 100, the vibration of the photoconductor 140 is suppressed while the vibration of the photoconductor 140 is suppressed.
Can be reduced. In addition, it is not necessary to increase the fixing strength of the photoconductor 140 to the support portions 121 and 131, and the cost can be reduced.

(E) The cleaning member 210, the charging roller 220, and the transfer roller 230, which are contact members, are brought into contact with the outer peripheral surface of the photosensitive member 140. Since the body 140 is supported from inside by the backup rollers 151, 152, and 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 photosensitive member 140,
The toner remaining on the outer peripheral surface of the photoreceptor 140 can be reliably removed and charged reliably. Also, at the transfer position, the photoconductor 140 can be reliably brought into contact with the intermediate transfer belt 400 at the transfer roller 230 portion.

Further, if the cleaning member 210 or the like is brought into contact with the photosensitive member 140 without the backup roller 151 or the like, the photosensitive member 140 having a thin cylindrical shape may be creep-deformed. According to the photoreceptor unit 100 of the embodiment, such a fear is also eliminated.

(F) Both ends 141 of the photosensitive member 140 are supported and fixed by a pair of disk-shaped members 120 and 130 rotatably attached to the shaft 110, and are backed up inside the photosensitive member 140. Roller 1
Since the units 51, 190 and the like are unitized by being attached to the shaft 110, handling becomes easy.

(G) Like the backup roller 190, the backup roller 151 and the like support the photosensitive member 140 from inside while being urged by the urging means 160, so that the photosensitive member 140 and the backup roller The position accuracy with respect to 151 etc. is improved.

Further, the disk-shaped members 120 and 130 have
Positioning portions 121b and 131b for positioning the backup roller 151 and the like in the supporting direction are provided, and the urging force of the urging means 160 is received by the positioning portions 121b and 131b. Such a force is prevented from acting, so that the inner surface of the photoconductor 140 is reduced in abrasion. Further, the photosensitive member 140 with respect to the support portions 121 and 131
It is not necessary to make the fixing strength excessive, and the cost can be reduced.

(H) Since the backup member 190 is constituted by a rotatable roller, a smooth rotation state of the photosensitive member 140 can be obtained, and the photosensitive member 140 can be rotated smoothly.
Can be reduced.

Therefore, according to the photoconductor unit 100, the vibration of the photoconductor 140 is suppressed while the vibration of the photoconductor 140 is suppressed.
Can be further reduced.

[0115]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The positional accuracy of the backup roller in the radial direction is desirably about ± 100 μm. The positional accuracy in the circumferential direction (the rotation direction of the photoconductor 140) is ± 1.
It is desirable to keep it within ゜.

The charge roller 22 with respect to the photosensitive member 140
0, the contact amount of the developing roller 310 and the transfer roller 230 (the concave amount of the photoconductor 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. 7, 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 may be provided between 7c and the spring hook portion 178 of the mounting plate to urge the backup roller 151 and the like outward in the radial direction. Although the backup roller 151 and the like are illustrated in FIG. 7, this urging means may be employed for the backup roller 190.

The backup rollers 151, 152, 153 for contact members other than the developing roller 300 need not always be provided.

[0120]

According to any one of the photoreceptor units according to the first to fourth aspects, it is possible to obtain a stable and stable contact state with the hard developing roller, and it is possible to reliably drive the photoreceptor unit. Can be

Further, according to the photoreceptor unit of the present invention, when there are a plurality of contact positions of the developing roller, the number of backup members is reduced by one as compared with the case where the backup member is arranged at the contact position. Can be reduced.

According to the photoreceptor unit of the third aspect,
The positional accuracy between the photoconductor and the backup member is improved, and unnecessary force is prevented from acting on the photoconductor.
The drive torque of the photoconductor can be reduced while suppressing the vibration of the photoconductor.

According to the photoreceptor unit of the fourth aspect,
A smooth rotation state of the photoconductor can be obtained,
The load on the photoconductor can be reduced, so that the driving torque of the photoconductor can be further reduced while suppressing the vibration of the photoconductor.

[0124]

[Brief description of the drawings]

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

FIG. 2 is a left side view of the photoconductor unit.

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

FIG. 4 is a diagram showing a fixing structure of an end portion of a photoconductor, 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 side view showing a modification of the urging means.

FIGS. 8A and 8B are explanatory diagrams of a conventional technique.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 photoconductor unit 110 shaft 120 disc-shaped member 121 b positioning unit 130 disc-shaped member 131 b positioning unit 140 photoconductor 190 backup roller (backup member) 160 urging means 300 developing roller 301 contact position

Claims (4)

[Claims] 1. A shaft that does not rotate by itself, a pair of disk-shaped members rotatably mounted on the shaft, and a disk-shaped member having both ends supported and fixed by the pair of disk-shaped members. A thin cylindrical photoreceptor having flexibility that rotates together with the photoreceptor, attached to the shaft inside the photoreceptor, and near a contact position where the developing roller contacts the photoreceptor from outside. And a backup member made of an elastic body for supporting the photoconductor from inside. 2. The photoconductor unit according to claim 1, wherein there are a plurality of contact positions of the developing roller, and the backup member is disposed between the contact positions. And a positioning portion provided on the disk-shaped member for positioning the backup member in the supporting direction. 3. A biasing device for biasing the backup member in the supporting direction The photoconductor unit according to claim 1, wherein: 4. The photoconductor unit according to claim 1, wherein the backup member is a rotatable roller.