JP2002341674A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of mitigating an impact when an electrophotographic process comes into contact with a photoreceptor with a simple constitution. SOLUTION: As for the image forming device with a transfer belt unit 12 which is arranged around the photoreceptor 1 and which can be attached/ separated to/from the photoreceptor 1, the device is provided with a transfer separation cam 25 for attaching/separating the transfer belt unit 12 to/from the photoreceptor 1, and provided that the rotating angle of the cam 25 from a position where the transfer belt unit 12 comes into contact with the photoreceptor 1 to a position where the unit 12 is separated furthest away from the photoreceptor 1 is expressed by α and the rotating angle of the cam 25 from the position where the transfer belt unit 12 is separated furthest away from the photoreceptor 1 to the position where the unit 12 comes in contact with the photoreceptor 1 is expressed by β, the relation of α<β is established.

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 copying machine, a facsimile, a printer, and the like. The present invention relates to a technique for mitigating a shock at the time.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus having a transfer means having a contact / separation mechanism for approaching / separating from / to a photoreceptor, vibration is applied to a machine main body by an impact at the time of the contact / separation operation. There is a problem that the image is adversely affected, and the waste toner in the transfer unit stains the main body of the machine. Further, in an image forming apparatus having an intermediate transfer unit such as a charging unit or a color printer which performs a contact / separation operation in the same manner as the above-mentioned transfer unit, there is a problem that an impact during the contact / separation operation adversely affects an image. For such defects,
Japanese Patent Application Laid-Open No. 5-158356 discloses a transfer mechanism for transferring a toner image from an intermediate transfer member of an image forming apparatus such as a color copying machine to transfer paper by using a spring and a cam to transfer a transfer roller to the intermediate transfer member. A mechanism for alleviating the impact at the time of pressing is disclosed. In JP-A-9-166947,
There is disclosed a technique in which a blade contacting / separating means is constituted by an eccentric cam, a half-rotation clutch and an arm in order to reduce an impact applied to the toner image carrier during a contacting / separating operation of the cleaning member.

[0003]

However, many of the above-mentioned prior arts have complicated components. That is, in Japanese Patent Application Laid-Open No. 5-158356, not the impact mitigation by controlling the rotation speed of the cam in combination with the control signal,
It involves manufacturing complexity. Japanese Patent Application Laid-Open No. 9-166947 is a technique relating to the contact / separation of the cleaning means, and is a driving control of the contact / separation by a signal, but is mechanically very complicated. SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus having a simple configuration and capable of reducing an impact when an electrophotographic process unit contacts a photosensitive member.

[0004]

According to a first aspect of the present invention, there is provided an image forming apparatus having an electrophotographic process means disposed around a photosensitive member and capable of moving toward and away from the photosensitive member. An eccentric contact / separation cam for bringing the electrophotographic process means into and out of contact with the photoreceptor, and adjusting the rotation angle of the contact / separation cam from the position where the electrophotographic process means is in contact with the photoreceptor to the maximum position. α <β, where α is the rotation angle of the contact / separation cam from the position where the electrophotographic process means is maximally separated from the photosensitive member to the position in contact with the photosensitive member. It is assumed that. According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, 1.2α <β is satisfied. The invention according to claim 3 is the same as the claim 1.
3. The image forming apparatus according to claim 2, wherein the electrophotographic process unit that comes into contact with or separates from the photoconductor is a transfer unit.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a main part of an image forming apparatus using a transfer belt. Around the photoreceptor 1, a charging roller 2, an optical writing system 3,
The electrophotographic process means of the developing unit 4, the transfer belt 6, the photosensitive member cleaning blade 8, and the static elimination light system 9 are arranged. A registration roller pair 5 is provided on the downstream side of the developing unit 4 and on the upstream side of the transfer belt 6 in the rotation direction of the photoconductor 1. Further, a fixing unit 7 is provided downstream of the transfer belt 6 in the transfer paper transport direction. The photosensitive member 1, the charging roller 2, and the photosensitive member cleaning blade 8
The photoconductor unit 10 is formed as one cartridge. Transfer belt 6 and belt cleaning blade 1
The transfer belt unit 12 is constituted by 1, and other members shown in FIGS. Other members will be described together with the following operation. An optical writing system 3 optically forms a latent image on the photoconductor 1 uniformly charged by the charging roller 2, and a visualized image (toner image) of toner is formed by the developing unit 4. The toner image formed on the photoreceptor 1 is transferred to the transfer paper conveyed through the registration roller pair 5 by the action of the transfer belt 6.
The transfer paper onto which the toner image has been transferred is conveyed by a transfer belt 6, and after the toner image is fixed by a fixing unit 7, is discharged outside the machine.

The untransferred toner on the photoconductor 1 that has not been transferred onto the transfer paper is scraped off the photoconductor 1 by the photoconductor cleaning blade 8. The residual charges on the photoreceptor 1 are neutralized by the neutralizing light system 9 to prepare for the next image forming operation.
The untransferred toner scraped off by the photoconductor cleaning blade 8 is sent to the toner conveying member 14 by the toner collecting blade 13, and is further sent to the near side by the toner conveying member 14. The toner sent to the near side is returned to the near side of the developing unit 4 through the collected toner conveying path, and is reused. The toner between the non-image area on the photoreceptor 1 and the transfer sheet adhered to the transfer belt 6 is scraped off from the transfer belt 6 by the belt cleaning blade 11, and a waste toner storage unit (not shown) of the transfer belt unit 12. Is stored in The toner stored in the transfer belt unit 12 is not reused and is discarded at the time of the periodic inspection. The developing unit 4 includes a developing sleeve 15 and a paddle 16, and the untransferred toner collected on the front side of the developing unit and the new toner dropped on the front side through the collected toner conveying path from the toner replenishing unit 17 are also separated. It is taken into the transport screw section inside the paddle 16 and transported to the back side. Then, the developer and the toner are sent from the back side to the front side and circulated by the spiral on the outer periphery of the paddle 16.

FIG. 2 is a front view showing a transfer belt contact / separation mechanism of the image forming apparatus, and FIG. 3 is a perspective view of the same. The transfer belt contact / separation operation will be described with reference to FIGS. The transfer belt 6 is stretched by a transfer drive roller 21, a transfer driven roller 22, and a bias roller 23, and the position of each roller is determined by a transfer belt frame (not shown). The frame, the rollers 21, 22, and 23 and the transfer belt 6 constitute a transfer belt unit 12, and the transfer belt unit 12 is in contact with and separated from the photoconductor 1. The contact / separation operation of the transfer belt unit 12 is performed by the transfer contact / separation clutch 2.
4, the transfer is performed by the transfer contact / separation cam 25 and the contact / separation lever 26. When the main motor is off and the P (photo) sensor pattern image is formed, the transfer contact / separation clutch 24 is turned on, and the transfer contact / separation cam 25 rotates by 回 転. And the contact / separation lever 26
Is pressed down (arrow 29 in FIG. 3), and the transfer belt unit 12
The (transfer belt 6) is separated from the photoconductor 1 (arrow 30 in FIG. 3).
Conversely, during a copy operation, the transfer contact / separation clutch 24 is turned on after a lapse of a predetermined time from the main motor ON, and the transfer contact / separation cam 25 is rotated by half, so that the contact / separation lever 26 is raised, and the transfer belt unit 12 is Contact 1 Further, a filler 28 provided coaxially with the transfer contact / separation cam 25 and a transfer home position sensor 27 detect whether the transfer belt unit 12 is in contact with the photosensitive member 1 or is separated therefrom. The present invention relates to rotation angle control of the transfer contact / separation cam 25 for bringing the transfer belt 6 into and out of contact with the photoreceptor 1. FIG. 4 is a diagram showing the relationship between the rotation angle and the position of the transfer contact / separation cam for explaining the first embodiment, and FIG.
FIG. 7 is a diagram illustrating a relationship between a rotation angle and a displacement amount of a transfer contact / separation cam for describing the embodiment. FIG. 8 is a diagram showing the relationship between the rotation angle and the position of the transfer contact / separation cam shown in comparison with the present invention, and FIG. 9 is a diagram showing the relationship between the rotation angle of the transfer contact / separation cam and the displacement amount.

In the examples shown in FIGS. 8 and 9, the rotation angle (α) required for the operation of separating from the photosensitive member 1 and the rotation angle (β) required for the contact operation with the photosensitive member 1 are equalized. 4 and 5
In the example of the cam 25 shown in FIG. 1 (in this example, one reciprocating operation is performed with one rotation), the rotation angle (α) required for the operation of separating from the photoconductor 1 is 135 ° smaller than half a rotation. Also,
The rotation angle (β) required for the contact operation with the photoconductor 1 is set to 225 °, which is larger than half a rotation, and the ratio of the displacement amount to the rotation angle is reduced. The rotation angle α is the rotation angle of the contact / separation cam from the position where the electrophotographic process unit is in contact with the photoconductor to the position farthest away from the photoconductor, and the rotation angle β is the maximum This is the rotation angle of the contact / separation cam from the position farthest from the end to the position contacting the photoconductor. As is apparent from FIG. 5, the transfer belt 6 is
The transfer contact / separation cam 25 with respect to the rotation angle at the time of contact comes from the displacement amount of the transfer contact / separation cam 25 with respect to the rotation angle at the time of separation from the cam.
Is small. In the present invention, the relationship between α and β is α <β, more specifically, 1.2α <β. By adopting such a configuration of the transfer contact / separation cam 25 and the transfer contact / separation clutch 24, even when the driving speed of the main body is restricted to a relatively high speed, the angle of β can be increased. , Transfer belt 6
Can be weakened, the toner can be prevented from scattering from the transfer belt unit 12, the abnormal image due to the impact can be eliminated, and the freedom of the layout of the main body drive system can be increased.

FIG. 6 is a view showing the relationship between the rotation angle and the position of the transfer contact / separation cam for explaining the second embodiment, and FIG. 7 is a transfer contact / separation cam for explaining the second embodiment. FIG. 6 is a diagram showing a relationship between a rotation angle and a displacement amount of the first embodiment. In this embodiment, the transfer belt 6 is moved twice by one rotation of the transfer contact / separation cam. Also in this embodiment, it can be seen that the rotation angle (β) required for the contact operation is larger than the rotation angle (α) required for the separating operation. This transfer contact / separation cam 2
In the case of 5, the same operation and effect as described above can be obtained. In the first and second embodiments, the transfer belt 6 has been described as an example of the electrophotographic process unit that comes into contact with and separates from the photoreceptor 1. Belts and the like are also targeted.

[0010]

According to the first and second aspects of the present invention, there is provided an eccentric contact / separation cam for bringing the electrophotographic process means into and out of contact with the photosensitive member, and the position where the electrophotographic process means is in contact with the photosensitive member. Α is the rotation angle of the contact / separation cam from the position farthest from the photosensitive member, and the rotation angle of the contact / separation cam from the position where the electrophotographic process means is farthest from the photosensitive member to the position in contact with the photosensitive member. When β is set, the relationship is set as α <β,
The ratio of the amount of displacement of the contact / separation cam to the rotation angle when the electrophotographic process means is in contact with the rotation angle when the electrophotographic process means separates from the photoreceptor is made smaller. It is possible to reduce the impact force at the time of contact with the photoreceptor and eliminate abnormal images due to the impact. According to the third aspect of the present invention, it is possible to reduce the impact force when the transfer unit comes into contact with the photoconductor, prevent the toner from scattering from the transfer unit, and eliminate an abnormal image due to the impact.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a main part of an image forming apparatus using a transfer belt.

FIG. 2 is a front view illustrating a transfer belt contact / separation mechanism of the image forming apparatus.

FIG. 3 is a perspective view of the contact / separation mechanism of FIG. 2;

FIG. 4 is a diagram illustrating a relationship between a rotation angle and a position of a transfer contact / separation cam for explaining the first embodiment of the present invention.

FIG. 5 is a diagram illustrating a relationship between a rotation angle and a displacement amount of a transfer contact / separation cam for explaining the first embodiment of the present invention.

FIG. 6 is a diagram illustrating a relationship between a rotation angle and a position of a transfer contact / separation cam for describing a second embodiment of the present invention.

FIG. 7 is a diagram illustrating a relationship between a rotation angle and a displacement amount of a transfer contact / separation cam for explaining a second embodiment of the present invention.

FIG. 8 is a diagram showing a relationship between a rotation angle and a position of a transfer contact / separation cam shown in comparison with the present invention.

FIG. 9 is a diagram illustrating a relationship between a rotation angle and a displacement amount of a transfer contact / separation cam shown in comparison with the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging roller 6 Transfer belt 12 Transfer belt unit 24 Transfer contact / separation clutch 25 Transfer contact / separation cam 26 Contact / separation lever 27 Transfer home position sensor

Claims (3)

[Claims] 1. An image forming apparatus having an electrophotographic process means disposed around a photoreceptor and capable of moving toward and away from the photoreceptor, an eccentric contact / separation cam for moving the electrophotographic process means toward and away from the photoreceptor. And the rotation angle of the contact / separation cam from the position where the electrophotographic process means is in contact with the photoconductor to the maximum position is α, from the position where the electrophotographic process means is maximally separated from the photoconductor. When the rotation angle of the contact / separation cam up to the position in contact with the photoconductor is β, α <
An image forming apparatus having a relationship of β. 2. The image forming apparatus according to claim 1, wherein
The relationship between the rotation angles α and β is such that 1.2α <β. 3. The image forming apparatus according to claim 1, wherein the electrophotographic process unit that comes into contact with and separates from the photosensitive member is a transfer unit.