JP2000155473A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration of image quality by providing a damper means moderating the moving speed of one end of a rocking member when one end of the rocking member is moved toward an image carrier (intermediate transfer body). SOLUTION: A transfer unit 7 is constituted of a secondary transfer roller 19 for transferring a toner image on the intermediate transfer body 15 to transfer paper P and a contacting/separating mechanism 21 making the roller 19 contact with/separate from the transfer body 15. The mechanism 21 is provided with a rocking plate (rocking member) 23 rocking centering around a rotary shaft 27, a spring 25 energizing the plate 23 toward the transfer body 15 (shown by an arrow (a)), a cam 29 abutting on the plate 23, and the damper means 31. The damper means 31 has a rack 33 and a rotary type damper 35 and moderates the moving speed of one end 23b of the plate 23 when one end 23b of the plate 23 is moved toward the transfer body 15. Thus, the transfer member is gently brought into contact with the transfer body 15, so that toner scattering is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as a color copying machine and a printer.

[0002]

2. Description of the Related Art Conventionally, as a contact / separation mechanism of a transfer roller provided so as to be able to freely contact / separate from an intermediate transfer member, Japanese Patent Laid-Open No. 5-15 / 1993
A technique using a cam and a spring as shown in JP-A-8356 and FIG. 5 is known. This contact / separation mechanism will be described with reference to FIG. 5. An intermediate transfer member 101 on which a toner image developed on the photoconductor 100 is transferred, a transfer roller 104 for transferring the toner image on the intermediate transfer member 101 to transfer paper 103, A swing member 106 that holds the transfer roller 104 and swings about a shaft 105;
Spring 107 biasing in the direction of
And a cam 108 that comes into contact with the cam 108.

In such a configuration, the swinging member 106 swings in accordance with the biasing force 107 of the spring and the rotation of the cam 108, so that the transfer roller 104 can freely contact and separate from the intermediate transfer body 101. Become.

As disclosed in Japanese Patent Application Laid-Open No. 9-43999, a rack is provided on a swing member that holds a transfer roller and swings about an axis, and a driving force from a drive source is mounted on the rack. A technique is known in which a gear for transmitting the transfer is meshed, and a swing member is swung by rotation of the gear to move the transfer roller toward and away from the intermediate transfer body.

[0005]

However, in the former technique, when the rotation speed of the cam 108 is high, the transfer roller 104 is not used.
However, there is a problem that a large impact is caused when the toner comes into contact with the intermediate transfer member 101, the toner image on the intermediate transfer member 101 is scattered, and image quality is deteriorated such as jitter (image distortion) and image shift. For this reason, it is necessary to reduce the rotation speed of the cam 108. However, in order to reduce the rotation speed of the cam 108, for example, a stepping motor or the like is required, and the configuration becomes complicated.

Also, in the latter technique, similarly to the above-described technique, there is a problem that a mechanism for driving the gear is complicated in order to rotate the gear slowly.

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 preventing a deterioration in image quality.

[0008]

According to a first aspect of the present invention, there is provided an image transfer device for transferring a toner image onto a transfer material by pressing a transfer material against the image support with the image support carrying the toner image. In an image forming apparatus provided with a member and a contact / separation mechanism for bringing a transfer member into and out of contact with an image carrier, the contact / separation mechanism has a rotating shaft at one end and a swinging shaft holding the transfer member at the other end. A moving member, a spring for urging the other end of the oscillating member toward the image carrier, and a cam for moving the other end of the oscillating member away from the image carrier against the urging force of the spring And damper means for reducing the moving speed of the other end of the swing member when the other end of the swing member moves toward the image carrier.

According to the first aspect of the invention, when the toner image on the image carrier is transferred to the transfer material, the other end of the swing member is directed toward the image carrier by the rotation of the cam and the urging force of the spring. The transfer member moves and comes into pressure contact with the image carrier. At this time, since the moving speed of the other end of the swinging member is reduced by the damper means, the other end moves slowly to the image carrier, and the transfer member comes into gentle contact with the image carrier. Therefore, the impact when the transfer member contacts the image carrier is small.

For example, when the cam rotates rapidly, the impact when the transfer member comes into contact with the image carrier increases, but even in such a case, the moving speed of the other end of the swinging member is controlled by the damper means. Is alleviated, the swinging member slowly moves toward the image carrier, and the transfer member comes into gentle contact with the image carrier. The transfer member gently in contact with the image carrier presses the transfer paper against the image carrier by the urging force of the spring, and transfers the toner image on the image carrier to the transfer paper.

According to the present invention, the structure is simple because only the damper means is provided, and the impact at the time of contact is small, so that scattering of toner is prevented, and image quality such as jitter (image distortion) and image misalignment is reduced. To prevent a drop.

According to a second aspect of the present invention, in the first aspect, the damper means includes a rack provided at the other end of the swinging member, and a rotating member meshing with the rack. And a rotary damper.

In the invention according to claim 2, for example,
Even when the cam rotates quickly, the rotating member rotates slowly, so that the other end of the swinging member moves slowly toward the image carrier. As the damper means, only a rotary damper having a rotary member meshing with the rack is provided, and the configuration is simple.

According to a third aspect of the present invention, in the first aspect of the invention, the damper means is provided at the other end of the swing member, and expands and contracts with the movement of the other end of the swing member. And a telescopic damper.

In the invention according to claim 3, for example,
Even when the cam rotates rapidly, the telescopic damper extends slowly, so that the other end of the swing member moves slowly toward the image carrier. The damper means is simply provided with a telescopic damper, and has a simple configuration.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment will be described below with reference to FIGS. 1 and 2 of the accompanying drawings. FIG.
FIG. 2 is a configuration diagram schematically showing an image forming unit 1 of a color copying machine to which the present invention is applied, and FIG.
FIG. 9 is a configuration diagram illustrating a state in which the reference numeral 9 is separated from the intermediate transfer member 15.

The image forming section 1 has a photoreceptor unit 3, an intermediate transfer unit 5, and a transfer unit 7.
In addition, in addition to the above-described color copiers, for example,
A paper feed unit for feeding the transfer paper P to the image forming unit 1; an exposure device for forming an electrostatic latent image on the photoconductor 9 by exposure; a developing device for developing the electrostatic latent image on the photoconductor 9 as a toner image; Although a fixing device and the like for fixing the toner image transferred to the paper P are arranged, illustration and description thereof are omitted in the present embodiment.

The photoreceptor unit 3 has a photoreceptor 11 stretched over a plurality of rollers 9, and the photoreceptor 11 carries a first color toner image developed by a developing device. This first color toner image is transferred to the intermediate transfer body 15 of the intermediate transfer unit 5.

The intermediate transfer unit 5 includes a plurality of rollers 13
An intermediate transfer member (image carrier) 15 stretched over the first transfer roller 17 and a primary transfer roller 17 are provided. The primary transfer roller 17 transfers the first color toner image of the photoconductor 11 to the intermediate transfer body 15,
Thus, the intermediate transfer body 15 carries the first color toner image.

Next, the second color toner image developed on the photoconductor 11 is transferred to the intermediate transfer body 15. in this way,
In the color copying machine, the above steps are repeated to transfer a plurality of color toner images on the intermediate transfer body 15 in a superimposed manner, and the intermediate transfer body 15 carries the plurality of color toner images. The plurality of color toner images are collectively transferred to the transfer paper P by the transfer unit 7, and the plurality of color toner images on the transfer paper P are fixed by the fixing device.

The transfer unit 7 is a secondary transfer roller (transfer member) for transferring the toner image on the intermediate transfer body 15 to the transfer paper P.
19, and a contact / separation mechanism 21 for moving the secondary transfer roller 19 toward and away from the intermediate transfer member 15.

The secondary transfer roller 19 presses the transfer material P against the intermediate transfer member 15 by a spring 25 to be described later, Transfer paper (transfer material) for color toner images
Transfer to P.

The contact / separation mechanism 21 includes a swinging plate (swinging member) 23 swinging about a rotation shaft 27 and a spring for urging the swinging plate 23 in the direction of the intermediate transfer member 15 (see arrow a). 25
, A cam 29 abutting on the rocking plate 23, and the damper means 3
And 1.

The swinging plate 23 has a rotating shaft 27 at one end 23a.
And a secondary transfer roller 29 is held at the other end 23b. Reference numeral 30 in the figure denotes a guide plate for guiding the transfer paper P to the fixing device. The guide plate 30 is provided at one end 23a of the swing plate 23 in the present embodiment. The guide plate 30 may be provided separately from the swinging plate 23, and may be any as long as it can guide the transfer paper P to the fixing device.

The other end 23b of the oscillating plate 23 is urged by the spring 25 in the direction of the intermediate transfer member 15 (see the arrow a). As is apparent from FIG. , The secondary transfer roller 29 presses the transfer material P against the intermediate transfer body 15.

A cam 29 is in contact with the other end 23b of the swinging plate 23. The cam 29 moves the other end 23b of the swinging plate 23 in the middle against the urging force of the spring 25. It is moved in a direction away from the transfer body 15. That is, the other end 23 b of the swinging plate 23 is moved by the rotation of the cam 29 to the intermediate transfer body 1.
5 (see FIG. 2) or approach the intermediate transfer member 15.

The damper means 31 has a rack 33 and a rotary damper 35, and the other end 2 of the rocking plate 23.
3b is moderated. The rack 33 includes the swing plate 23
And moves integrally with the swinging plate 23. The rotating member 34 of the rotary damper 35 meshes with the rack 33.

The rotary damper 35 is formed by applying a high-viscosity oil (oil) to a rotary member 34 meshing with the rack 33 and a sliding portion 39 between the rotary member 34 and a shaft 37.
Due to the friction of the oil applied to the sliding portion 39, the rotating member 34 rotates slowly (slowly). The damper means 31 includes a rack and a rotating member 3 meshing with the rack 31.
4, the configuration is simple.

Next, the operation of the first embodiment will be described based on the above configuration. When the intermediate transfer body 15 sequentially transfers the toner images of each color from the photoconductor 11, FIG.
As shown in (2), the secondary transfer roller 19 is separated from the intermediate transfer body 15 by the rotation of the cam 29. This is because before the toner image of the intermediate transfer body 15 is transferred to the transfer paper P,
This is to prevent the toner image from adhering to the secondary transfer roller 19.

After transferring the toner images of a plurality of colors to the intermediate transfer member 15 and then transferring the toner images of the colors to the transfer paper P at once, the cam 29 rotates and the other end 2 of the rocking plate 23 is rotated.
3b is the intermediate transfer member 15 by the urging force of the spring 25.
Move towards. At this time, the other end 23 of the swing plate 23
Since the moving speed b is moderated by the damper means 31, the b moves slowly to the intermediate transfer member 15, and the secondary transfer roller 19 comes into gentle contact with the intermediate transfer member 15.
Therefore, the impact when the secondary transfer roller 19 contacts the intermediate transfer body 15 is small.

For example, when the cam 29 rotates rapidly, the impact when the secondary transfer roller 19 comes into contact with the intermediate transfer member 15 increases. However, even in such a case, the rotating member 34 rotates slowly. The other end 23 of the rocking plate 23
b moves slowly toward the intermediate transfer member 15, and the secondary transfer roller 19 comes into contact with the intermediate transfer member 15 gently.

The secondary transfer roller 19 gently in contact with the intermediate transfer member 15 presses the transfer paper P against the intermediate transfer member 15 by the urging force of the spring 25, and
Are transferred to the transfer paper P.

By providing the damper means 31, the secondary transfer roller 19 can be gently brought into contact with the intermediate transfer member 15, and the impact upon contact can be reduced. Further, since the impact at the time of contact is small, scattering of toner is prevented, and deterioration of image quality such as jitter (distortion of image) and image shift is prevented.

Next, a second embodiment will be described with reference to FIGS. 2 and 3 of the accompanying drawings. In the description, portions having the same functions and effects as described above are denoted by the same reference numerals. The description is omitted. FIG. 3 is a configuration diagram schematically illustrating the image forming unit 1 of the image forming apparatus according to the second embodiment. FIG. 4 illustrates a state in which the secondary transfer roller 19 in FIG. FIG. 3 is a configuration diagram showing a state in which

In the second embodiment, the other end 2 of the rocking plate 23 is used.
3B is different from the above-described embodiment in that a telescopic damper 41 is provided as damper means in 3b.

The telescopic damper 41 has a cylindrical body 43 fixed to the main body, and a sliding body 45 that slides inside the cylindrical body 43. Part 2
3b is moderated. Tip 45a of sliding body 45
Is fixed to the other end 23 b of the swing plate 23, and the sliding body 45 expands and contracts with the movement of the other end 23 b of the swing plate 23. The telescopic damper 41 is provided with a sliding member 45 by hydraulic pressure.
The movement speed of the other end 23b of the rocking plate 23 is moderated by relaxing the movement of the swinging plate 23 to the intermediate transfer body 15 (when the sliding body 45 extends from the cylindrical body 43, it slowly extends).

When a plurality of color toner images of the intermediate transfer member 15 are transferred onto the transfer paper P, the secondary transfer roller 19 (see FIG. 4) separated from the intermediate transfer member 15
9 and the urging force of the spring 25, the swing plate 2
3 moves toward the intermediate transfer body 15 together with the other end 23a.

At this time, the other end 23b of the rocking plate 23 is
Since the movable speed is reduced by the telescopic damper 41, the movable member slowly moves to the intermediate transfer member 15, so that the secondary transfer roller 19 comes into gentle contact with the intermediate transfer member 15. Therefore, the impact when the secondary transfer roller 19 contacts the intermediate transfer body 15 is small.

For example, when the cam 29 rotates rapidly, the impact when the secondary transfer roller 19 comes into contact with the intermediate transfer member 15 increases, but even in such a case, the sliding member 45 extends slowly. As a result, the other end 23b of the swinging plate 23 moves slowly toward the intermediate transfer body 15, and the secondary transfer roller 19 comes into gentle contact with the intermediate transfer body 15. With a simple configuration in which the telescopic damper 41 is provided at the other end 23b of the rocking plate 23, the same operation and effect as those of the first embodiment are exerted.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

For example, in the present embodiment, the secondary transfer roller 19 is used as a transfer member (transfer electrode). However, the present invention is not limited to this.
A transfer member of another shape such as a blade may be used. Further, the image bearing member with which the transfer member contacts is not limited to the intermediate transfer member, but also includes a transfer member that contacts the photosensitive member.

Further, although the telescopic damper 41 is of the hydraulic type, it may be of a type such as a pneumatic one or a spring. The sliding member 45 moves slowly toward the intermediate transfer member 15. I just want it. Although the present invention is applied to a color copying machine, the same operation and effect can be obtained by applying the present invention to a printer, a facsimile, a monochrome copying machine, or the like.

[0043]

According to the first aspect of the present invention, the transfer member can be gently brought into contact with the image carrier with a simple structure having damper means, and the impact at the time of contact is small.
It prevents scattering of toner and prevents deterioration of image quality such as jitter (image distortion) and image shift.

According to the second aspect of the invention, in addition to the effect of the first aspect, the rotary damper having a rotary member meshing with the rack is merely provided as the damper means, and the configuration is simple. .

According to the third aspect of the present invention, the effect of the first aspect is achieved, and the damper means is simply provided with a telescopic damper, so that the structure is simple. .

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing an image forming unit of an image forming apparatus according to a first embodiment.

FIG. 2 is a configuration diagram illustrating a state in which a secondary transfer roller in FIG. 1 is separated from an intermediate transfer member.

FIG. 3 is a configuration diagram schematically illustrating an image forming unit of an image forming apparatus according to a second embodiment.

FIG. 4 is a configuration diagram illustrating a state where the secondary transfer roller of FIG. 3 is separated from an intermediate transfer member.

FIG. 5 is a configuration diagram schematically showing the vicinity of a conventional contact / separation mechanism.

[Explanation of symbols]

 Reference Signs List 15 intermediate transfer member (image carrier) 19 secondary transfer roller (transfer member) 21 separation / contact mechanism 23 rocking plate (rocking member) 25 spring 27 rotation shaft 29 cam 31 damper means 33 rack 34 rotation member 35 rotary damper 41 Telescopic damper P Transfer paper

Claims (3)

[Claims] An image carrier that carries the toner image; a transfer member that presses the transfer material toward the image carrier to transfer the toner image onto the transfer material; and a transfer member that contacts the image carrier. An image forming apparatus comprising: a contacting / separating mechanism configured to separate a swinging member having a rotation shaft at one end and a transfer member at the other end; A spring for urging the carrier toward the carrier, a cam for moving the other end of the rocking member away from the image carrier against the urging force of the spring, and a cam for moving the other end of the rocking member to the image carrier. An image forming apparatus comprising: a damper for reducing a moving speed of the other end of the swing member when moving toward the image forming apparatus. 2. The damper means according to claim 1, further comprising a rotary damper having a rack provided at the other end of the swing member and a rotary member meshing with the rack. Image forming apparatus. 3. The device according to claim 1, wherein the damper means includes a telescopic damper which is provided at the other end of the swing member and expands and contracts with movement of the other end of the swing member. Image forming apparatus.