JP2000227736A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the cause of run out caused by the fitting or driving of a photoreceptor in an image forming device adopting an electrophotographic method. SOLUTION: This device is provided with a driving shaft 430 to be rotary- driven on a rear side of a rear side supporting blade 410 in freely rotationally, projecting front ward from the rear side supporting blade 410 in piercing through the photoreceptor 100 and projecting the front side of the photoreceptor 100, and a coupling member in the inside position of the photoreceptor 100 of this driving shaft 430. Moreover, the device is provided with a front side tapered frame member 353 and the rear side tapered frame member 460 respectively having tapered surfaces 353a and 460a being symmetrically rotated on the periphery of the rotary axis of the driving shaft 430 while being in contact with a front side flange 102 and the rear side flange 101 constituting the photoreceptor 100.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a copying machine or a printer.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic system, that is, an electrostatic latent image is formed on a photoreceptor, the electrostatic latent image is developed with toner to obtain a toner image, and the toner image is finally formed into a predetermined image 2. Description of the Related Art Image forming apparatuses such as copying machines and printers that transfer and fix onto paper have become widespread. In recent years, color image forming apparatuses that form a color image by applying the electrophotographic method have appeared. I have.

In this electrophotographic image forming apparatus, a drum-shaped photosensitive member is usually used as a photosensitive member on which an electrostatic latent image is formed, and the photosensitive member is rotated while rotating the drum-shaped photosensitive member. A method of forming an electrostatic latent image thereon is employed. In this case, it is known that unevenness of rotation or misalignment of the drum-shaped photoreceptor affects the accuracy of the electrostatic latent image, that is, the quality of an image finally formed on paper. I have. In particular, in the case of a color image forming apparatus that has recently appeared, such rotation unevenness and misalignment greatly affect color misregistration on a color image, and how to reduce those errors is a major problem. .

[0004] In constructing an image forming apparatus, it is general to assemble such that support plates are respectively provided at the back and front of the apparatus, and various elements constituting the image forming apparatus are supported by the support plates. It is a target. The drum-shaped photoconductor is also supported by these support plates. Error factors such as uneven rotation and centering when rotating the drum-shaped photoreceptor also exist in the photoreceptor itself, but the method of supporting the support plate and the rotational driving force to the photoreceptor Will be greatly affected by the way in which it is transmitted.

[0005] Here, how to support the drum-shaped photoreceptor on the support plate and how to transmit the rotational driving force to the photoreceptor will be considered here.

FIG. 9 is an explanatory view of a conventional mounting structure for a drum-shaped photosensitive member. FIG. 9 shows a mounting structure generally used in the related art. The photoconductor 10 includes a rear flange 11, a front flange 12, and a cylindrical photosensitive sheet 13 supported by the flanges 11, 12.
The rear flange 11 has a hole 111 at its center.
, And the drive shaft 22 is inserted therein. The drive shaft 111 is rotatably supported by the rear support plate 31, and is driven to rotate further behind the rear support plate 31 (the right side of the rear support plate 31 in FIG. 9). The drive shaft 111 supports the coupling member 222 with the coil spring 221 interposed. The coupling member 222 is prevented from rotating with respect to the drive shaft 22, and only linear motion is allowed. The coupling member 222 is fitted in a hole 112 a provided in the fitting portion 112 of the rear flange 11 of the photoconductor 10, and when the drive shaft 22 rotates, the rotational force is transmitted via a coil spring 221. Coupling member 222
To the rear side flange 11 to rotate the photoconductor 10. A front shaft 21 is provided integrally with the front flange 12 at the center of the front flange 12 of the photoreceptor 10, and the front shaft 21 is rotatably supported by a front support plate 32.

[0007]

In the case of the photoreceptor mounting drive mechanism shown in FIG. 9, the shaft supporting the photoreceptor 10 is separated into a drive shaft 21 and a front shaft 22, and the photoreceptor 1
There is a problem that it is difficult to obtain a zero axis.

Further, there is some play between the hole 111 at the center of the rear flange 11 of the photoreceptor 10 and the drive shaft 22, and there is a problem that it is difficult to completely eliminate the play.

For these reasons, the structure shown in FIG. 9 has a high possibility that a large amount of misalignment will occur when the photosensitive member is driven to rotate, and is a structure that is difficult to employ in an image forming apparatus aiming at higher quality. is there.

The present invention has been made in view of the above circumstances, and has as its object to provide an image forming apparatus having a structure suitable for forming a high-quality image by suppressing a cause of occurrence of misalignment due to mounting and driving of a photoconductor. Aim.

[0011]

An image forming apparatus according to the present invention for achieving the above object forms an electrostatic latent image on a rotating drum-shaped photoreceptor, and develops the electrostatic latent image with toner. In an image forming apparatus that obtains a toner image and finally transfers and fixes the toner image on a predetermined sheet to form an image on the sheet, the photoconductor includes a rear flange, a front flange, A cylindrical photosensitive sheet supported by these flanges, and the image forming apparatus is rotatable on a rear support plate and a front support plate for mounting the photoconductor, and a rear support plate. Is supported by the rear support plate, projects forward from the rear support plate, further penetrates through the rear flange and front flange of the photoconductor, protrudes forward of the photoconductor, and is rotatably supported by the front support plate. Drive driven by rotation The drive shaft is attached to the drive shaft via a spring at a position inside the photoreceptor of the drive shaft and the drive shaft, is linearly movable with respect to the drive shaft, and is spring-biased forward with respect to the drive shaft. A coupling member for transmitting rotation to the photoreceptor, wherein a front flange constituting the photoreceptor is fitted to the coupling member at a portion located inside the photoreceptor, and the rotational force of the drive shaft is And a fitting portion for receiving the same.

In the image forming apparatus of the present invention, the image forming apparatus further includes a front plate supported by the front support plate and rotatably supporting a portion of the drive shaft protruding forward of the photoreceptor. , The drive shaft may be rotatably supported by the front support plate.

In the image forming apparatus of the present invention, since the drive shaft penetrates the photoconductor, the axis of the photoconductor is properly determined, and it is possible to prevent the occurrence of misalignment during rotation.

Further, the image forming apparatus of the present invention includes a coupling member attached via a spring to a portion of the drive shaft corresponding to the inside of the photoreceptor, and connects the photoreceptor via the coupling member. Since the rotary member is driven to rotate, the coupling member may be smaller than a coupling member provided behind the photosensitive member.

In the image forming apparatus of the present invention, a front taper frame member and a rear taper frame having a tapered surface rotationally symmetric about a rotation axis of a drive shaft, which contact the front flange and the rear flange constituting the photosensitive member, respectively. Preferably, a member is provided.

By doing so, the play between the drive shaft and the photoreceptor can be eliminated, and rotation unevenness and centering can be suppressed more reliably.

Further, in the image forming apparatus of the present invention, the coupling member has a cylindrical shape having a drive shaft penetrating therein, and the drive shaft includes
Preferably, the photosensitive member has an outer diameter smaller than the outer diameter of a portion penetrating the rear flange.

The photoreceptor usually has a limited life and is usually replaced periodically. For this reason, the photoconductor is often configured to be able to be pulled out to the front of the image forming apparatus.

In the present invention, since the coupling member is disposed at the position inside the photoconductor, the photoconductor can be drawn forward with the drive shaft remaining by setting the above-mentioned dimensional restriction.

[0020]

Embodiments of the present invention will be described below.

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

A drum-shaped photoconductor 110 is disposed inside the image forming apparatus 100.
Are driven to rotate at a constant speed in the direction of arrow A.

The photosensitive member 110 is a charged scorotron 1
The surface of the laser light source 13 is uniformly charged by the laser light source 13.
Scanning is performed by the laser beam 131 emitted from 0 and modulated according to image information, and an electrostatic latent image is formed on the surface.

The electrostatic latent image formed on the surface of the photoconductor 110 is developed by the developing device 140. The developing device 140 includes four developing devices 141, 142, 143, and 144 that perform development with toners of Y (yellow), M (magenta), C (cyan), and K (black). This is a rotary developing device, and the electrostatic latent image formed on the photoconductor 110 is developed with any one color toner at a time.

A toner image obtained by developing the electrostatic latent image on the photoconductor 110 with toner is transferred onto the intermediate transfer belt 160 by the action of the primary transfer roll 150. The intermediate transfer belt 160 is an endless belt stretched by a plurality of rolls and circulating in the direction of arrow B.

After the toner image is transferred to the intermediate transfer belt 160, the photosensitive member 110 is neutralized by a pre-cleaning corotron 170, cleaned by a fur brush 181 and a cleaning blade 182 constituting a cleaner 180, and cleaned by a charging scorotron 120. Charging for forming the next electrostatic latent image is performed.

On the photoconductor 110, electrostatic latent images corresponding to the respective colors of Y, M, C, and K are sequentially formed, and the respective electrostatic latent images are formed of the respective colors of Y, M, C, and K. The toner images of the respective colors are sequentially transferred so as to be stacked on the intermediate transfer belt 160, and color toner images of four colors of Y, M, C, and K are formed on the intermediate transfer belt 160. It is formed. During that time, the secondary transfer roll 190 and the cleaner 200 are kept separated from the intermediate transfer belt 160.

The image forming apparatus is provided with three sheet trays 211, 212, and 213, and the sheet trays 211, 212, and 213 store, for example, sheets of different sizes. Which one of the plurality of paper trays 211, 212, and 213 forms an image on the paper stored in the paper tray is determined as follows.
It is specified by the user or automatically determined according to the size of the image to be formed.

When the fourth color toner image is transferred onto the intermediate transfer belt 160 to form a color toner image of four colors of Y, M, C, and K, the color image formed on the intermediate transfer belt 160 is formed. In synchronization with the transfer of the toner image to the secondary transfer position where the secondary transfer roll 190 is provided, the sheet 220 taken out from one of the three sheet trays 211, 212, and 213 is removed. The sheet is conveyed to a secondary transfer position via a predetermined sheet conveyance path 230, and the secondary transfer roll 190 contacts the back surface of the sheet 220, and the intermediate transfer belt 160
The upper color toner image is transferred to the sheet 220. The paper 220 to which the color toner image has been transferred is further conveyed and sent to the heat fixing device 240, where the heat fixing rolls 241,
242 heats and pressurizes, thereby melting the toner and forming a color image on the paper,
The image is sent out of the image forming apparatus.

On the other hand, the intermediate transfer belt 160
After the color toner image is transferred thereon, the surface is cleaned by the cleaner 200 before receiving the next toner image transfer. Further, the secondary transfer roll 190 is also a cleaner 250.
Is cleaned by

FIG. 2 is a perspective view of the photosensitive member unit incorporated in the image forming apparatus shown in FIG.
FIG. 3 is a perspective view of the photoreceptor unit shown in FIG.

In the photoconductor unit 300, in addition to the drum-shaped photoconductor 110, a charging scorotron 120 and a pre-cleaning corotron 170 shown in FIG. The front cover 310 is provided on the front side, and the rear cover 320 is provided on the rear side. Further, this unit is provided with a handle 330 to be held by hand and a rail 340 for sliding when the unit is pulled out or pushed inside the image forming apparatus. That is, the photoconductor unit 300 is configured to be able to be pulled forward from the image forming apparatus when the operation of the image forming apparatus is stopped.

As shown in FIG. 3, the rear cover 320 is formed with a hole 321 into which a drive shaft to be described later is inserted. When the photoconductor unit 300 is pulled out to the front of the image forming apparatus, the drive shaft is Is pulled out while remaining inside the image forming apparatus. Also, holes 32
The front end of the drive shaft inserted from 1 is rotatably supported by the front plate 350. The front plate 350 is provided with a hole 351. When the photoconductor unit 300 is pushed into the inside of the image forming apparatus, a forwardly protruding pin 421 provided on the front support plate 420 (see FIG. 4) is formed. 351 so that the photosensitive member unit is positioned with respect to the front support plate.

FIG. 4 is a diagram showing the internal structure of the photoconductor unit 300.

The photosensitive member 100 includes a rear flange 101,
Front flanges 102 and their flanges 101, 10
2 is provided with a cylindrical photosensitive sheet 103 supported by the second photosensitive sheet.

FIG. 4 shows a rear support plate 410 and a front support plate 420 fixed to the image forming apparatus main body for mounting the photoreceptor 100 and the like. Drive shaft 430 extends to connect 420. The drive shaft 430 is rotatably supported by the rear support plate 410 and protrudes forward of the rear support plate 410. The drive shaft 430 further extends through the central openings 101 a and 102 a of the rear flange 101 and the front flange 102 of the photoconductor 100. The photoconductor 100 passes through the photoconductor 100, projects forward of the photoconductor 100, and is rotatably supported by the front plate 350. As described above, the front plate 350 is provided with the holes 351, and the pins 421 provided on the front support plate 420 enter the holes 351, so that the front plate 350 is formed.
Are positioned with respect to the front support plate 420, so that the drive shaft 430 is rotatably supported by the rear support plate 410, and is also rotatable with respect to the front support plate 420 by the interposition of the front plate 350. It is supported by. The drive shaft 430 is rotationally driven by a drive mechanism (not shown) behind the rear support plate 410.

As described above, in the present embodiment, the drive shaft 430 penetrating the cylindrical photosensitive member 100 and rotatably supported by the front and rear support plates 410 and 420 is provided.
Alignment during rotation of the photoconductor is suppressed to a low level.

The drive shaft 430 has a coil spring 440 surrounding the drive shaft 430 at an internal position of the photoconductor 100 when the photoconductor 100 is arranged at a fixed position inside the image forming apparatus. The rear end 440a of the coil spring 440 is restricted in position by the drive shaft 430, and the front end 440b is restricted in position by the coupling member 450. The coupling member 450 has a cylindrical shape through which the drive shaft 430 penetrates, and a pin 451 fixed to the coupling member 450 enters into a vertically extending elongated hole 431 provided in the drive shaft 430. , And can linearly move in the front-rear direction with respect to the drive shaft while being urged forward by the coil spring 440. The coupling member 450 is fitted to the rear end fitting portion 102 c of the front flange 102 of the photoconductor 100, which is located inside the photoconductor, and
It has a role of transmitting the rotation driving force of 0 to the photoconductor 100. The shape and the like of the fitting portion will be described later. The outer diameter d ₁ of the coupling member 450 is equal to the outer diameter d of a portion of the drive shaft 430 penetrating the rear flange 101.
_The coupling member 450 has an outer diameter smaller than ₂ so that the coupling member 450 does not get caught on the photoconductor 100 when the photoconductor unit is pulled out forward or pushed into a fixed position.

A cylindrical rear tapered piece member 460 is fixed to the drive shaft 430 with the drive shaft 430 penetrating therethrough. The rear taper piece 460 has a front end portion which is rotationally symmetric about the rotation axis of the drive shaft and has a tapered surface 460 inclined forward.
a.

The front plate 350 supports a front taper piece 353 urged rearward by a coil spring 352 surrounding the drive shaft 430. The front taper top member 353 also has an opening through which the drive shaft penetrates in the center, has a rotationally symmetrical shape around the rotation axis of the drive shaft, and has a tapered surface 353a inclined backward. .

The tapered surface 35 of the front taper piece 353
3a is in contact with the front end 102b of the opening 102a of the front flange 102 of the photoconductor 100, and the tapered surface 460a of the rear taper piece 460 described above is the rear end 101 of the opening 101a of the rear flange 101 of the photoconductor 100.
b contacts the drive shaft 430 and the photoconductor 10
The axis of 0 is aligned exactly. In the present embodiment, with such a configuration, misalignment during rotation is further suppressed.

FIG. 5 is a cutaway perspective view showing the inside of the photosensitive member.

The coupling member 450 has a fitting projection 452 protruding forward, while the fitting portion 102c of the front flange 102 of the photoreceptor 100 has a plurality of fitting grooves 102d. Is inserted into the fitting groove 102d of the fitting portion 102c.
The fitting part 402c of the coupling member 450 and the front flange 102 is fitted. When the drive shaft 430 rotates in this state, the rotational driving force is applied to the coupling member 45.
The rotation of the drive shaft 430 is transmitted to the photosensitive member 100 via the fitting portion 102c of the front flange 102 and the front flange 102, so that the photosensitive member 100 rotates.

Here, when the photosensitive member unit is pushed into a fixed position from the state of being pulled out to the front of the image forming apparatus, the fitting projection 452 of the coupling member 451 is inserted into the groove 102d of the fitting portion 102c of the front flange 102. Without getting in
Even when the coil spring 440 is contracted and the tip of the fitting protrusion 452 and the tip of the protrusion between the two grooves 102d of the fitting part 102c remain in contact with each other, the drive shaft 430 rotates. Is started, the fitting protrusion 452 is
There is no problem because it enters d. That is, in the case of the configuration shown in FIG. 5, the operator who handles the photoconductor unit can push the photoconductor unit without worrying about whether or not the fitting has been performed correctly, and the operation is facilitated. ing.

FIG. 6 is a view showing a structure in which a coupling mechanism is provided at a rear portion of the photosensitive member. This structure is not an embodiment of the present invention but a comparative example to be compared with the embodiment.

Here, a coupling member 820 urged forward by a coil spring 810 and a fitting member 830 integrally fixed to the rear flange 101 constituting the photosensitive member 100 are shown. The rotational driving force of the drive shaft is transmitted to the photoconductor 100 via the coupling member 820 and the fitting member 830.

In this case, since the coupling member 820 needs to straddle the rear tapered top member 460, it becomes a large member, and the structure becomes complicated, which leads to an increase in the size of the entire image forming apparatus and disadvantages in cost. Becomes

On the other hand, in the present embodiment, FIGS.
Since the coupling mechanism is provided inside the photoreceptor 100 as shown in (1), a small-sized member is required, and the structure is advantageous in terms of space.

FIG. 7 shows the rear flange 102 shown in FIG.
It is a figure which shows the groove shape of the fitting part 102c.

As shown in FIG. 7A, the groove has a linear portion 1021 parallel to the rotation axis and a tapered portion 1022 at a portion on the back side following the linear portion 1021.

The fitting protrusion 452 of the coupling member 450 shown in FIG. 5 has a straight portion 1021 as shown in FIG.
7 (C), when the coupling member is provided with an engagement pin 453, as shown in FIG. It is configured to be able to receive at.

As described above, the fitting groove 102c has a shape that allows a plurality of structures on the coupling member side, and the fitting protrusion 452 as shown in this embodiment (FIG. 5).
And a mechanism provided with a coupling member having an engagement pin as shown in FIG. 7C.

As shown in FIG. 7A, the protrusion 1023 between the two fitting grooves is formed at an acute angle, and the fitting protrusion 452 of the coupling member 450 or the engaging pin 4 is formed.
53 easily enters the fitting groove 102c.

FIG. 8 shows the fitting portion 10 of the rear flange 102.
It is a figure which shows another example of the shape of the groove of 2c, and the shape of the fitting protrusion of the coupling member 450.

FIG. 8A shows the shape of the groove on the flange side. One side of this groove is formed only with a straight portion 1024, the other side is a tapered portion 1025 near the entrance, and a straight line on the far side. A portion 1026 is formed.

On the other hand, FIG. 8B shows the fitting projection of the coupling member, and the straight portion 102 of the fitting groove of the flange.
A straight portion 4501 is formed on the side corresponding to No. 4 and a tapered portion 4502 is formed on the other side. The tapered portion 4502 of the fitting protrusion is formed in the tapered portion 10 of the fitting groove shown in FIG.
8 is formed at an acute angle than that of FIG.
As shown in (C), the fitting protrusion 4502 is provided at the contact point 10 between the tapered portion 1025 of the fitting groove and the straight portion 1026 behind the fitting groove.
27, thereby preventing backlash of the fitting projection that has entered the fitting groove.

The coupling member rotates in the direction of the arrow shown in FIG. 8C, and transmits the rotational driving force to the flange.

[0058]

As described above, according to the present invention,
When the drum-shaped photoreceptor rotates, misalignment can be suppressed to an extremely low level, and a high-quality image can be formed.

[Brief description of the drawings]

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

FIG. 2 is a perspective view of a photoreceptor unit incorporated in the image forming apparatus shown in FIG.

FIG. 3 is a perspective view of the photoconductor unit shown in FIG.

FIG. 4 is a diagram showing an internal structure of a photoconductor unit 300.

FIG. 5 is a perspective view showing the inside of the photoconductor in a cutaway manner.

FIG. 6 is a diagram illustrating a structure in which a coupling mechanism is provided at a rear portion of a photoconductor.

FIG. 7 is a view showing a groove shape of a fitting portion of a rear flange.

FIG. 8 is a diagram showing another example of the shape of the groove of the fitting portion of the rear flange and the shape of the fitting protrusion of the coupling member.

FIG. 9 is an explanatory view of a conventional mounting structure for a drum-shaped photoconductor.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 image forming apparatus 101 photoreceptor 101 a central opening 101 b rear end 102 front flange 102 a central opening 102 b front end 102 c fitting portion 102 d fitting groove 110 photoreceptor 120 charged scorotron 130 laser light source 131 laser light 140 developing devices 141, 142, 143, 144 Developing device 150 Primary transfer roll 160 Intermediate transfer belt 170 Pre-cleaning corotron 180 Cleaner 190 Secondary transfer roll 200 Cleaner 211, 212, 213 Paper tray 220 Paper 230 Paper transport path 240 Thermal fixing device 250 Cleaner 300 Photoconductor unit 310 Front cover 320 Rear cover 321 hole 330 Handle 340 Rail for slide 350 Front plate 351 hole 430 Drive shaft 440 Rubane 450 cup after the ring member 460 side Tepakoma 460a tapered surface 352 coil spring 353 front Tepakoma member 353a tapered surface

Claims (4)

[Claims] An electrostatic latent image is formed on a rotating drum-shaped photoconductor, and the electrostatic latent image is developed with toner to obtain a toner image. The toner image is finally formed on a predetermined sheet of paper. An image forming apparatus that forms an image on the sheet by transferring and fixing, wherein the photoconductor includes a rear flange, a front flange, and a cylindrical photosensitive sheet supported by these flanges. A back support plate and a front support plate for attaching the photoreceptor, rotatably supported by the back support plate, and projecting forward from the back support plate. A drive shaft that penetrates a rear flange and a front flange of the photoconductor, protrudes forward of the photoconductor, and is rotatably supported by the front support plate; the drive shaft is rotatably driven on the rear surface of the rear support plate; Of the shaft, Inside position of the light body,
A cup attached to the drive shaft via a spring, which is directly movable with respect to the drive shaft and is spring-biased forward with respect to the drive shaft, for transmitting rotation of the drive shaft to the photoconductor. A ring member, and a front flange constituting the photoreceptor has a fitting portion that receives the rotational force of the drive shaft by being fitted to the coupling member at a portion located inside the photoreceptor. An image forming apparatus comprising: 2. While being supported by the front support plate,
A front plate that rotatably supports a portion of the drive shaft that protrudes forward of the photoreceptor, wherein the drive shaft is rotatably supported by the front support plate by interposition of the front plate. The image forming apparatus according to claim 1, wherein 3. A front taper top member and a rear taper top member having a taper surface rotationally symmetrical around a rotation axis of the drive shaft, the front taper top member and the rear taper top member being in contact with a front flange and a rear flange constituting the photoreceptor, respectively. The image forming apparatus according to claim 1, wherein: 4. The coupling member has a cylindrical shape with the drive shaft penetrating therethrough, and the coupling member has an outer diameter smaller than an outer diameter of a portion penetrating a rear flange forming the photoconductor. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus has a small outer diameter.