JP2000122472A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device which is capable of obtaining sure, stable contact of an image carrier, a developing roller, and a cleaning blade, is excellent in durability and handling, and is capable of sure driving. SOLUTION: An image carrier 140, which has flexibility, and a cylindrical shape with thin wall, is supported by a pair of disk-shaped members rotatably attached to a shaft 110 that does not rotate by itself. A backup drum 150, which is attached to the shaft 110 inside it and supports the image carrier 140 from inside in the position where a cleaning blade 210 is made to abut against the image carrier 140 from the outside of it, is rotatably provided on the shaft 110 by means of an eccentric bearing 154. The image carrier and backup drum are made to abut against each other at both ends 210a of the cleaning blade.

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), transfer means for transferring the toner image developed by the developing means to a transfer medium such as paper, and a cleaning blade for removing the 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.

Further, as the developing means, a roller-shaped one which is brought into contact with the surface of the photoreceptor is known, and as the roller, a hard roller and a roller made of soft rubber are known.

[0005] A hard photoconductor drum is used as the photoconductor,
If a hard roller is used as the developing 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. It is difficult. If the two do not contact uniformly, there is a problem that a gap is locally formed to cause uneven development, or the photosensitive drum and the developing roller are damaged by being pressed more than necessary.

Therefore, it is not usually practiced that both the photosensitive member and the developing roller to be brought into contact with the photosensitive member are made of a hard material. Is made of soft rubber, and when a hard developing roller is used, a photosensitive belt having flexibility is used as a photosensitive member.

However, when the developing roller to be brought into contact with the photoreceptor is made of a soft rubber, conductive particles such as carbon are dispersed to impart conductivity to the developing roller. There is a problem that the rubber hardness changes due to the unevenness and variation of the roller, the hardness on the roller surface varies, and a good adhesion state to the photoreceptor cannot be obtained. Conversely, if the dispersion amount of carbon is reduced to obtain a good adhesion state to the photoconductor,
There is a problem that the conductivity is varied and causes uneven development.

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

However, when a photoreceptor belt is used as the photoreceptor, at least two belts are required to support the photoreceptor belt.
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. 5 is a diagram showing the photoconductor driving device.
(A) is a side view, (b) 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. A friction coefficient between the drive roller 21 and the photoreceptor belt 20 which is inside and rotates the photoreceptor belt 20 is set smaller than a friction coefficient between the drive roller 21 and the photoreceptor belt 20. A pressing member 22 that slidably presses the photosensitive belt 20 while keeping the photosensitive belt 20 in close contact with the drive roller 21 within a predetermined range in the circumferential direction is provided. In FIG. 5, 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 the pressing member 22 is not provided. 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 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 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.

However, Japanese Patent Application Laid-Open No. 4-188 described above
In the photoconductor driving device described in Japanese Patent Application Publication No. 164 (FIG. 5), the pressing member 2 partially provided on the periphery of the photoconductor belt 20 is used.
2, the photoreceptor belt 20 is guided at the entrance portion 22a when the photoreceptor belt 20 enters the pressing member 22.
Bending stress is likely to be generated at the peripheral portion (edge portion) of the photoconductor belt 20, thereby causing a problem that the edge 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 assembled 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.

Therefore, it is possible to solve the above-mentioned various problems and to obtain a reliable and stable contact state between the image carrier and the developing roller and the cleaning blade, and to improve the durability and handleability of the image carrier. An image carrier unit (and an image forming apparatus) that is excellent and can reliably drive the image carrier has already been proposed in Japanese Patent Application Laid-Open No. H10-239934.

FIG. 6 is a partially omitted front sectional view showing the image carrier unit, and FIG. 7 is a partial side view showing a state where the image carrier unit is incorporated in an image forming apparatus.

As shown in FIG. 6, the image carrier unit 1 has a shaft 2 which does not rotate by itself, and a pair of disk-shaped members 3, 3 rotatably mounted on the shaft 2.
A thin cylindrical image carrier 4 having flexibility, both ends of which are supported and fixed by the pair of disk members 3, 3, and driven to rotate together with the disk members 3, 3; The image carrier 4 is attached to the shaft 2 by side plates 17 and 17 inside the image carrier 4 and the cleaning blade 11 (see FIG. 7) abuts against the image carrier 4 from outside. And a backup roller 5 for supporting the roller from inside.

As shown in FIG. 7, the image forming apparatus includes the image carrier unit 1, a charging roller 6 for uniformly charging the outer peripheral surface of the image carrier 4, and a charging roller 6. Is selectively exposed to the outer peripheral surface.
And an exposure unit (not shown) for forming an electrostatic latent image by applying a toner as a developer to the electrostatic latent image formed by the exposure L to form a visible image (toner image). A developing device 8 (Y, M, CK), a transfer roller 10 for transferring the toner image developed by the developing roller 7 to the intermediate transfer belt 9, and a transfer contacting the image carrier 4 from outside; A cleaning blade 11 for removing toner remaining on the outer peripheral surface of the image carrier 4 later.

Reference numeral 12 denotes a backup roller for the charging roller 6, and reference numeral 13 denotes a backup roller for the transfer roller 10.

In FIG. 6, reference numeral 14 denotes one disk-shaped member 3.
A driving gear 15 fixed to the first member is an interlocking means for transmitting the driving force to the other disk-shaped member and interlocking the disk-shaped members 3 and 3.

In this conventional apparatus, each of the backup rollers 5, 12, and 13 has a side plate 17 such that the outer peripheral surface thereof is in light contact with the inner peripheral surface of the image carrier 4 or is extremely close thereto. , 17.

According to the image forming apparatus described in JP-A-10-239934, the following operation and effect can be obtained.

(A) In the image carrier unit 1, both ends of a thin cylindrical image carrier 4 are supported and fixed by a pair of disk-shaped members 3, 3 rotatably mounted on a shaft 2. Therefore, when the disk members 3 and 3 are driven to rotate, the image carrier 4 is reliably driven to rotate.

Further, since both ends of the image carrier 4 are supported and fixed by the pair of disk-shaped members 3, the durability is excellent.

(B) The image carrier 4 is a flexible thin-walled cylindrical shape and both ends are supported by the disk-shaped members 3, 3. The central portion 4a not supported by the disk-shaped members 3, 3 can be deformed inward.

Therefore, the central portion 4 of the image carrier 4
Since the part of a that is not supported from the inside by the backup roller can be used as a so-called pseudo soft material, even if the developing roller 7 to be brought into contact with the part is a hard roller or the like, it is reliable. A stable contact state can be obtained, and an image can be reliably formed on the image carrier 4 or the image can be carried.

On the other hand, a cleaning blade 11 for removing the developer remaining on the outer peripheral surface of the image carrier 4 is provided.
Are brought into contact with each other.
Is supported from the inside by the backup roller 5, so that the cleaning blade 11 can be reliably contacted.

(C) In the image carrier unit 1, both ends of the image carrier 4 are supported and fixed by a pair of disk-shaped members 3, 3 rotatably mounted on the shaft 2. Since the backup roller is attached to the shaft 2 by the side plates 17 and 17 inside the carrier 4, the backup roller is unitized, so that the image carrier unit 1 itself can be easily handled.

That is, the method disclosed in Japanese Unexamined Patent Application Publication No.
According to the image forming apparatus described in Japanese Patent Application Laid-Open Publication No. H10-209, it is possible to obtain a reliable and stable contact state between the image carrier and the developing roller and the cleaning blade, and the image carrier has excellent durability and handleability. Can be reliably driven.

[0039]

There is naturally a limit in manufacturing the components of the image carrier unit 1 with high accuracy, and an error always occurs. Therefore, the inner peripheral surface of the image carrier 4 is opposed to the inner peripheral surface. The distance between the backup roller and the outer surface of the backup roller also varies for each image carrier unit.

For this reason, the above-mentioned Japanese Patent Application Laid-Open No. H10-2399
The image forming apparatus described in Japanese Patent Application Publication No. 34-34 has the following problem.

That is, the backup roller 5 in the above-mentioned conventional apparatus should be arranged such that the outer peripheral surface thereof is in light contact with the inner peripheral surface of the image carrier 4 or is extremely close to it. Due to the variation, as shown in FIG. 8, at the position where the cleaning blade 11 is to be brought into contact, the inner surface 4a of the image carrier 4
The gap g between the backup roller 5 and the outer surface 5a may be too large. FIG. 8 illustrates a state in which the cleaning blade 11 is abutted and the image carrier 4 is supported from the inside by the backup roller 5 at the abutting position. The outer surface 5a of the roller 5 is in contact with the outer surface 5a.
Denotes the inner surface 4a of the image carrier 4 and the outer surface 5 of the backup roller 5 before the cleaning blade 11 is brought into contact with the cleaning roller 11.
3 shows an interval from the position a.

If the distance g is too large, the both ends 11 of the cleaning blade 11
At the position a (only one is shown), the end 11a of the cleaning blade 11 is greatly deformed into a curved shape along the shape of the image carrier 4 as compared with the central portion 11b. The contact force becomes too large, and as a result, the cleaning blade 11
I was turned over.

An object of the present invention is to solve the above problem and prevent the cleaning blade from being turned up.

[0044]

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. An image carrier unit having a backup member attached to the image carrier and supporting the image carrier from the inside at a contact position where the cleaning blade abuts against the image carrier from the outside; A cleaning blade for abutting against the image carrier of the body unit from outside thereof to remove the developer remaining on the outer peripheral surface of the image carrier, the cleaning blade comprising: At both ends positions, wherein said image bearing member and said backup member is in contact.

According to a second aspect of the present invention, there is provided the image forming apparatus according to the first aspect.
In the image forming apparatus described above, the backup member has an outer diameter slightly smaller than the inner diameter of the image carrier, and includes a backup drum rotatably supported on the shaft via an eccentric bearing. It is characterized by having.

[0046]

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

A shaft that does not rotate by itself, a pair of disk-shaped members rotatably mounted on the shaft,
A thin cylindrical image carrier having flexibility, both ends of which are supported and fixed by the pair of disc-shaped members, and which is rotationally driven together with the disc-shaped members, and which is attached to the shaft inside the image carrier. An image carrier unit having a backup member for supporting the image carrier from the inside at the contact position where the cleaning blade contacts the image carrier from the outside; A cleaning blade for contacting the image carrier from the outside to remove the developer remaining on the outer peripheral surface of the image carrier; and the same operation and effects as those of the above-described (a) to (c). That is, a reliable and stable contact state between the image carrier and the developing roller and the cleaning blade can be obtained, the durability and handleability of the image carrier are excellent, and the image carrier is reliably driven. Effect that bets can be obtained.

Further, according to the image forming apparatus of the first aspect, since the image carrier and the backup member are in contact with each other at the ends of the cleaning blade, the end of the cleaning blade is located at the center. As a result, it is not greatly deformed in a curved shape along the shape of the image carrier, and the contact force between the cleaning blade and the image carrier at both end positions of the cleaning blade does not become too large, as a result,
The effect of preventing the cleaning blade from being turned up is obtained.

According to the image forming apparatus of the second aspect, in the image forming apparatus of the first aspect, the backup member has an outer diameter slightly smaller than the inner diameter of the image carrier, and On the other hand, since the backup drum is rotatably supported via an eccentric bearing, the following operation and effect can be further obtained.

That is, since the backup drum is rotatably supported on the shaft via the eccentric bearing, the structure is simple and the assembly can be easily performed. Therefore, it can be produced with high accuracy.

Further, 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. The image carrier can be supported over a wide range from the inside at the contact position where the cleaning blade contacts from the outside. Accordingly, the developer is more reliably removed by the cleaning blade.

[0052]

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

FIG. 1 is a cross-sectional view showing an image carrier unit in an embodiment of the image forming apparatus according to the present invention (FIG. 3).
2 is a schematic partial side view of an image forming apparatus incorporating the image carrier unit, and FIG. 3 is a partially enlarged view of FIG.

As shown in FIGS. 1 and 3, the image carrier unit 100 has a shaft 110 which does not rotate by itself,
A pair of disk-shaped members 120, 120 rotatably attached to the shaft 110, and both ends supported and fixed by the pair of disk-shaped members 120, 120, rotate together with the disk-shaped members 120, 120. A thin cylindrical image carrier 140 having flexibility, and a cleaning blade 210 attached to the shaft 110 inside the image carrier 140 and contacting the image carrier 140 from the outside. Backup drum 1 as a backup member for supporting image carrier 140 from the inside at the contact position
50.

Each of the pair of disk-shaped members 120, 120 is rotatably provided on a shaft 110 via a bearing 114, and the outer peripheral surfaces 121, 121 of the disk-shaped members 120, 120 enable the image carrier. 140 at both ends 14
1 is supported. Both ends 141 of the image carrier 140 are formed on the outer peripheral surfaces 121 and 12 by appropriate means, for example, by bonding.
Fixed to 1. A driving gear (not shown) is fixed to at least one of the disc-shaped members 120 on an outer surface thereof.

In this embodiment, the image carrier 140 is configured as a photosensitive member, and is formed by forming a photosensitive layer on the surface (outer peripheral surface) of a flexible thin cylindrical base material. I have. 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 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 base material thickness of 20 to 200 μm and the base material diameter of 10 to 300 mm. OPC is mainly made of resin, and therefore is excellent in flexibility. However, in order to secure adhesion to the base material and to take measures against laser light interference, the OPC is made of OPC.
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.

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 formed slightly smaller than the inner diameter D2 of the image carrier 140. Side plate 15
1 is provided with a bearing hole 153, and an eccentric bearing 154 is interposed between the bearing hole 153 and the shaft 110. Therefore, the backup drum 150 is rotatably supported on the shaft 110 via the eccentric bearing 154. As shown in FIG. 3, the eccentric bearing 154 has an eccentric amount E on the contact position side (the right side in FIG. 3) where the cleaning blade 210 and the charging roller 220 contact.
As a result, a part of the outer peripheral surface of the backup drum 150 (the outer peripheral surface of the cylindrical member 152) is relatively eccentric at the contact position.
40 is supported from the inside.

Since the backup drum 150 is rotatably supported on the shaft 110 via the eccentric bearing 154, as shown in FIG. 3, at least at the contact position of the cleaning blade 210 and the charging roller 220, When the outer peripheral surface 152 a of the cylindrical member 152 contacts the inner peripheral surface 140 a of the photoconductor 140, the cylindrical member 152 rotates following the photoconductor 140.

The image carrier unit 100 as described above is
As shown in FIG. 2, a driving gear (not shown) of the main body of the image forming apparatus is engaged with a driving gear (not shown) provided on the disc-shaped member 120, which is incorporated in the image forming apparatus. The body (photoconductor) 140 is driven to rotate in the direction of the arrow.

In FIG. 2, L is a laser beam for selectively exposing the surface of the photosensitive member 140, and 300 (Y, M, C, K)
Denotes a developing device, 210 denotes the cleaning blade described above, 2
Reference numeral 20 denotes the charging roller 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 charging roller 220 is incorporated in the sub case 240, and is driven by a compression spring 221 (see FIG. 3).
The photosensitive member 140 is rotated by being pressed against the photosensitive member 140.

The laser beam L is emitted from an exposing unit (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 of the developing devices 300 (Y, M, C, K) has a built-in yellow, magenta, cyan, and black toner. Each of the developing devices 300 is configured to be able to come into contact with and separate from the photoconductor 140, and only one of the developing devices can come into contact with the photoconductor 140 during image formation. Reference numeral 310 (Y, M, C, K) denotes a developing roller that comes into contact with the photoconductor 140, and is constituted by a metal roller having a roughened surface or a hard resin roller.

The intermediate transfer belt 400 is brought into contact with the photosensitive member 140, and this contact position forms a primary transfer portion T1. The intermediate transfer belt 400 includes a drive roller 410, a tension roller 420, a backup roller 430 for the secondary transfer roller 460, and a cleaning blade 470.
Are wound around a backup roller 440 and a positioning roller 450 for forming the primary transfer portion T1, and are circulated by a drive roller 410 in the direction of the arrow shown in the figure. In a process in which the intermediate transfer belt 400 is driven to circulate, in the primary transfer portion T1, the photosensitive member 1
40 is transferred onto the intermediate transfer belt 400, and the toner image transferred onto the intermediate transfer belt 400 is
The image is transferred onto a recording medium (not shown) such as a sheet supplied between the secondary transfer roller 460 and the intermediate transfer belt 400.

The upper portion of the cleaning blade 210 is fixed to the blade holder 211 as shown in FIG. The blade holder 211 is a plate-like body extending in a direction orthogonal to the paper surface of FIG. 3, and arms 212 (only one is shown) provided at both ends of the blade holder 211 are swung with respect to a side 241 of the sub case 240 by a shaft 213. Mounted as possible. A blade urging spring (compression coil spring) 242 is provided between the sub case 240 and the blade holder 211.
The tip (edge) of the cleaning blade 210 is pressed against the surface of the photoconductor 140 by the urging force of the blade urging spring 242 and the elastic force of the blade 210 itself.

The sub case 240 has a receiving portion 243 for receiving the toner scraped off by the blade 210.

A rake sheet 244 is provided below the tip of the cleaning blade 210. The base of the rake sheet 244 is fixed to the sub case 240, and the leading edge of the rake sheet 244 is pressed against the surface of the photoconductor 140 by the elastic force of the sheet 244 itself, and
And prevents the toner scraped off by the cleaning blade 210 from leaking downward.

A toner conveying screw 245 is provided in the sub case 240, and the toner is conveyed by the toner conveying screw 245 toward a waste toner tank (not shown).

The sub-case 240 incorporating the cleaning blade 210 and the like is
0 can be combined with a single unit.

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

(I) When a print command signal (image forming signal) is inputted from a host computer (not shown) 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 image information of the first color (for example, yellow) by an exposing means (not shown). A latent image is formed.

(Iv) The developing roller 310 of the developing device 300Y for the first color (for example, yellow) is provided on the photosensitive member 140.
Only the Y contacts, the electrostatic latent image is developed, and the toner image of the first color (for example, yellow) is
Formed on 40.

(V) The toner image formed on the photosensitive member 140 is transferred onto the intermediate transfer belt 400 at the primary transfer portion T1, ie, between the photosensitive member 140 and the primary transfer roller 230. At this time, the secondary transfer roller 460 is separated from the intermediate transfer belt 400.

(Vi) After the toner remaining on the photoreceptor 140 is removed by the cleaning blade 210, the photoreceptor 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, the secondary transfer unit T2 (the intermediate transfer belt 400 and the secondary transfer roller 460)
The recording medium such as paper is supplied to the contact portion with the recording medium, and the toner image (basically a full-color image) on the intermediate transfer belt 400 is transferred onto the recording medium.

In the above-described image forming apparatus, for example, the shaft 110, the disc-shaped member 120, the image carrier 140, and the backup drum 150, which are components of the image carrier unit 100, are manufactured with high precision. Has its own limitations and errors always occur. In particular, the image carrier 1
When a nickel seamless tube manufactured by an electroforming method is used as the base material of the base 40, it is necessary to refresh the electroforming master in order to form the base material normally. Is smaller, the inner diameter (D2) of the base material is gradually reduced, so that the inner diameter of each image carrier 140 tends to vary.

Therefore, the inner peripheral surface of the image carrier 140
The space between the outer surface of the backup member and the outer surface of the backup member also varies depending on each image carrier unit.

In such a situation, if no measures are taken, the problem described above with reference to FIG. 8, that is, the cleaning blade may be turned up from its end. The problem arises.

Therefore, in this embodiment, even if there are some manufacturing errors in the components of the image carrier unit 100,
As shown in FIG. 4, the image carrier 140 and the backup drum 150 are brought into contact with each other at a position A at both ends 210a (only one is shown in FIG. 4) of the cleaning blade 210.

Specifically, the distance L from the support end of the image carrier 140 by the disk-shaped member 120 to the end 210a of the cleaning blade 210 is set relatively large, or the distance L is set relatively short. Also, by improving the flexibility of the image carrier 140, the image carrier 14 is positioned at the position A of the end 210 a of the cleaning blade 210.
0 and the backup drum 150 can be brought into contact with each other.

According to the above-described image forming apparatus, the following operation and effect can be further obtained as compared with the image forming apparatus described in JP-A-10-239934.

(1) As shown in FIG. 4, at the position A at both ends of the cleaning blade 210, the image carrier 14
0 and the backup drum 150 are in contact,
The contact force between the cleaning blade 210 and the image carrier 140 at both end positions A of the cleaning blade 210 becomes too large (the end portion 210a of the cleaning blade 210 is more curved than the central portion along the shape of the image carrier 140). The contact force does not increase due to the deformation (see FIG. 8), and as a result, the turning of the cleaning blade 210 is prevented.

That is, according to the image forming apparatus of this embodiment, a reliable and stable contact state between the image carrier 140 and the developing roller 310 and the cleaning blade 210 can be obtained. In addition to the effect of being able to reliably drive the image carrier 140 with excellent durability and handleability, the effect of preventing the cleaning blade 210 from being turned up can be obtained.

(2) The backup drum 150 is
Since the image carrier unit 100 is rotatably supported via the eccentric bearing 154, the structure of the image carrier unit 100 is simple and can be easily assembled. Therefore, it can be produced with high accuracy.

(3) 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 the eccentric bearing 154. At a contact position where the cleaning blade 210 contacts the image carrier 140 from the outside, the image carrier 140 can be supported over a wide range from the inside (see FIGS. 2 and 3). ). Therefore, the removal of the toner by the cleaning blade 210 is performed more reliably.

Further, since the backup drum 150 is in contact with the image carrier 140 over a wide range and is reliably driven and rotated with respect to the image carrier 140, the backup drum 150
In a case where the image carrier 140 is driven from one end by a driving gear provided on the image carrier 140, the backup drum 150 supports the driving force applied from one end of the image carrier 140 to the image carrier 140. The portion reliably functions as a transmission member for transmitting the image to the image carrier 140, and the image carrier 140 is driven satisfactorily.

[0090]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The shaft 110 is constituted by a metal shaft.

The side plate 151 of the backup drum 150,
The cylindrical member 152 is made of aluminum.

The positional accuracy of the backup drum 150 in the radial direction is desirably 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 (the concave amount of the image carrier 140) is desirably 0.5 mm or less.

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.

[0096]

According to any one of the first and second image forming apparatuses, a reliable and stable contact state between the image carrier and the developing roller and the cleaning blade can be obtained, and the durability of the image carrier can be improved. In addition to the effect of being able to reliably drive the image bearing member, it is possible to obtain the effect of preventing the turning of the cleaning blade.

Further, according to the image forming apparatus of the second aspect, the structure is simple and easy to assemble, and it is possible to produce with high accuracy, and the developer is more reliably removed by the cleaning blade. It will be.

[0098]

[Brief description of the drawings]

FIG. 1 is a cross-sectional view (a partly omitted II cross-sectional view in FIG. 3) showing an image carrier unit in an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a schematic partial side view of an image forming apparatus incorporating the image carrier unit.

FIG. 3 is a partially enlarged view of FIG. 2;

FIG. 4 is a schematic view showing a state where an image carrier and a backup member are in contact with each other at an end position of a cleaning blade, and is a view corresponding to a partially enlarged view of FIG. 1;

FIGS. 5A and 5B are explanatory diagrams of a conventional technique.

FIG. 6 is an explanatory diagram of a conventional technique.

FIG. 7 is an explanatory diagram of a conventional technique.

FIG. 8 is a conceptual diagram for explaining a problem.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 image carrier unit 110 shaft 120 disk member 140 photoreceptor (image carrier) 150 backup drum (backup member) 154 eccentric bearing 210 cleaning blade 310 developing roller

Claims (2)

[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 flexible thin cylindrical image carrier that is driven to rotate together with the image carrier; an inner portion of the image carrier, which is attached to the shaft, and a cleaning blade that contacts the image carrier from outside; An image carrier unit having a backup member for supporting the image carrier from the inside at the contact position, and an outer periphery of the image carrier which abuts against the image carrier of the image carrier unit from the outside. An image forming apparatus comprising: a cleaning blade that removes a developer remaining on a surface; wherein at both end positions of the cleaning blade, the image carrier and the backup member come into contact with each other. An image forming apparatus comprising Rukoto. 2. The backup member has an outer diameter slightly smaller than the inner diameter of the image carrier, and includes a backup drum rotatably supported on the shaft via an eccentric bearing. The image forming apparatus according to claim 1, wherein: