JP2002296872A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving device constituted so that uneven rotation is surely prevented with simple constitution and without requiring large-sized constitution. SOLUTION: This image forming device is equipped with a photoreceptor 2 on which an image of every separated color is formed, a primary transfer device 6 equipped with an intermediate transfer body 6C on which the image of every color formed on the photoreceptor 2 is superposed and transferred and a bias device 6D actuated when the image is transferred from the photoreceptor 2, a secondary transfer device constituted of a transfer roller 9 capable of contacting with/separating from the transfer body 6C and collectively transferring the image superposed and transferred on the transfer body 6C to a recording medium such as transfer paper by abutting on the transfer body 6C, and a cleaning device 6E capable of contacting with/separating from the transfer body 6C. In the device, the driving part 6A of the transfer body 6C is provided with constitution 20 for making load different from that at the transferring operation time act in accordance with the contacting/separating operation of the roller 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus, and more particularly, to a configuration for preventing an image combining position shift in an image forming apparatus capable of forming an image of a plurality of colors.

[0002]

2. Description of the Related Art In general, a photoconductor constituting a latent image carrier is used in an image forming apparatus such as a copying machine or a printer. In an image forming apparatus, for example, taking a copying machine as an example,
After the photosensitive member is uniformly charged, light is written on the latent image carrier using a laser beam or the like to form a latent image corresponding to a document, and then the latent image is processed with a developer to form a visible image. An image is obtained by transferring a visible image to a transfer paper or the like.

In recent years, color image forming apparatuses for forming images of not only a single color but also a plurality of colors including a full color have been proposed and put into practical use. In a color image forming apparatus, a latent image is formed on a photoreceptor by reflected light obtained by performing color separation of reflected light from a document, and in a printer, irradiation images corresponding to color information form latent images. The visible image is processed with a developer of a color that is complementary to the color-separated reflected light or irradiation light, and the process of primary transferring the visible image to the intermediate transfer member is repeated. The corresponding visible images are collectively transferred to a transfer paper or the like by a secondary transfer process.

In a transfer step performed by a color image forming apparatus, for example, as disclosed in Japanese Patent Application Laid-Open No. Hei 8-190239, a structure in which a transfer roller that can be brought into contact with and separated from a photosensitive member is used. . In this configuration, a cleaning device is provided in addition to the transfer roller as a member that contacts and separates from the photoconductor.

[0005]

Generally, when another member comes into contact with a member rotating at a constant linear velocity, the contact pressure becomes a load, and the on-axis torque of the rotating member is reduced. And the linear velocity of the rotating member changes. For this reason,
As disclosed in the above-mentioned publication, when the transfer roller is brought into contact with the photoconductor and batch transfer is performed, if the next latent image formation is performed at this time, the latent image formation on the photoconductor is performed. There is a possibility that the start position is shifted, and if the start position is shifted, a color shift or banding occurs, resulting in a loss of image quality.

If the latent image formation is started after the load fluctuation has converged, the above-described problem does not occur. However, if the standby is continued until the load fluctuation is converged, the image forming time becomes longer, and the demand for high-speed operation has recently been increasing. Can not be achieved.

SUMMARY OF THE INVENTION An object of the present invention is to provide a simple configuration and a reliable configuration without requiring a large configuration in view of the problems of color misregistration and banding in the above-described conventional image forming apparatus, particularly an apparatus capable of forming a plurality of color images. An object of the present invention is to provide a driving device and an image forming apparatus having a configuration capable of preventing rotation unevenness.

[0008]

According to the first aspect of the present invention,
A photoreceptor capable of forming an image for each color separation, an intermediate transfer member capable of superimposing and transferring an image of each color formed on the photoreceptor, and a bias device operating when transferring an image from the photoreceptor; A secondary transfer device, and a transfer roller capable of coming into contact with and separating from the intermediate transfer body and capable of transferring an image superimposed and transferred on the intermediate transfer body to a recording medium such as transfer paper by contact with the transfer roller. An image forming apparatus provided with a secondary transfer device, and a cleaning device capable of moving toward and away from the intermediate transfer body, wherein the drive unit of the intermediate transfer body performs a transfer operation in accordance with the movement of the transfer roller. It is characterized in that a configuration for applying a load different from the time is provided.

According to a second aspect of the present invention, in the configuration for applying the load, a friction generating member which can be brought into contact with and separated from a rotating member disposed in a driving section of the intermediate transfer body is used.

According to a third aspect of the present invention, the friction generating member used in the structure for applying the load is brought into a non-contact state when the transfer roller contacts the intermediate transfer member.
It is characterized in that the transfer roller is in a contact state when the transfer roller is separated from the intermediate transfer member.

According to a fourth aspect of the present invention, in the configuration in which the load is applied, a load equivalent to an on-axis torque of the transfer roller generated when the transfer roller is in contact with the intermediate transfer member is applied. It is characterized by:

The invention according to claim 5 is characterized in that the friction generating member has a configuration for monitoring a change in load on the transfer roller.

According to a sixth aspect of the present invention, as a configuration for monitoring a change in load on the transfer roller, a control capable of counting the number of copies is connected to an input side, and an alarm unit is connected to an output side. Unit is used, the control unit,
It is characterized in that the number of copies to be considered as the deterioration of the friction generating member is registered in advance, and the time when the load changes is warned by comparing the number of copies with the actual number of copies.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram for explaining a main configuration of a color image forming apparatus, which is one of the image forming apparatuses using the developing device according to the present embodiment. In FIG. 1, a color image forming apparatus 1 includes a photosensitive member 2 as a latent image carrier in a housing. The photoconductor 2 is a belt (hereinafter, referred to as a belt) wound around a pair of pulleys 2A and 2B.
Photoreceptor belt), and each pulley 2A, 2B
Is rotated in the clockwise direction indicated by the arrow and moves in the direction indicated by the arrow. In FIG. 1, reference numeral 2C denotes a tension roller disposed inside the photoreceptor belt 2. Around the photoreceptor belt 2, a charging device 3, an optical writing device 4, a developing device 5, a primary transfer device 6, and a cleaning device 7 for executing an image forming process along the moving direction are arranged, respectively. .

The developing device 5 has a configuration in which developing units accommodating developers for a plurality of colors are arranged along the circumferential direction around the rotation axis O, and each developing unit is sequentially exposed to light. The developer is supplied so as to face the body belt 2 to form a visible image.

The primary transfer device 6 is a member for superimposing and transferring the image for each color separation formed on the photosensitive belt 2. For this reason, the primary transfer device 6 is wound around a pair of rollers 6A and 6B provided in a process cartridge 30 that can be inserted into and removed from the apparatus main body, and
And a transfer device 6D for setting a transfer bias is disposed at a position facing the photoreceptor belt 2 at a position facing the photosensitive belt 2. The transfer belt 6C has a cleaning device 6E provided with a cleaning blade that can be contacted during the non-transfer process.
The developer removed from the transfer belt 6C is disposed in the cleaning device 7 for the photoreceptor belt 2 via a conveying member 6F using a screw auger or the like and a collecting member (not shown) communicating therewith. Collection section 7
A.

The cleaning device 7 for the photosensitive belt 2 includes:
A cleaning member capable of contacting the photosensitive belt 2;
The developer removed from the photoreceptor belt 2 is introduced into the collecting section 7A together with the developer collected from the cleaning device 6E of the transfer belt 6C. The collection unit 7A includes a transfer belt 6C, a photoreceptor belt 2, a charging device 3, and a cleaning device 6E for the transfer belt 6C.
Are provided so as to be detachable from the process cartridges 30 that are collectively arranged, and when the developer is filled with waste developer, the developer can be taken out of the process cartridge 30 and the developer can be discarded. Has become. A part of the shape of the process cartridge 30 forms a guide surface of a recording medium fed from the sheet feeding device 8.

In the vicinity of the transfer device 6, a secondary transfer capable of collective transfer is carried out on the roller 6A side by opposing the expansion surface of the transfer belt 6C opposite to the surface facing the photosensitive belt 2 among the expansion surfaces of the transfer belt 6C. An apparatus 9 is provided so as to be able to approach and separate from the transfer belt 6C. The secondary transfer device 9 is configured by a transfer roller, and transfers the full-color image superimposedly transferred onto the transfer belt 6C onto a recording medium such as a transfer sheet fed from the sheet feeding device 8 at a time. To apply a bias.

The paper feeding device 8 includes a paper feeding cassette 8A for storing a recording medium such as transfer paper, a feeding roller 8B for feeding out the recording medium from the paper feeding cassette 8A, a conveying roller 8B1, and a registration roller 8B2. Provided.
In this embodiment, a part of the housing of the color image forming apparatus 1 (for convenience, indicated by reference numeral 1A) is provided as an openable and closable cover, and a manual paper feed tray 1B is provided therein. A conveyance path switching claw 8B3 for setting a conveyance path between the recording medium from the sheet feeding tray 8A and the recording medium from the manual sheet feeding tray 1B is provided in front of the registration roller 8B2. The route can be switched to be guided to the collective transfer device 9.

Behind the batch transfer device 9, a fixing device 1 for fixing an image transferred onto a recording medium such as transfer paper is provided.
The fixing device 10 is provided with a heating roller 10A having a built-in heater, and a pressure roller 10B which is brought into contact with and interlocks with the heating roller 10A. The recording medium fixed by the fixing device 10 is discharged onto a discharge tray 12 by a discharge roller 11. In FIG. 1, reference numeral 10C denotes an oil application device for preventing transfer of the developer.

In the color image forming apparatus 1 using the photoreceptor belt 2, when the electrostatic latent image for each color is processed by the developing device 5 into a visible image, the visible image is transferred to the transfer belt 6C of the transfer device 6.
To form a full-color image, and the full-color image is collectively transferred to a recording medium.

The transfer belt 6C serving as an intermediate transfer member is provided with a structure for preventing movement unevenness during the rotation movement of the transfer belt 6C. FIG. 2 is a schematic diagram for explaining an arrangement configuration of members related to the transfer belt 6C. In FIG. 2, the transfer belt 6C is a pair of rollers 6
A, 6B and is driven by
One of them, that is, a rotating shaft 6A1 of the roller 6A located on the driving side is for applying a load separately from a load generated when the transfer roller 9 constituting the secondary transfer device comes into contact with the transfer belt 6C. As a configuration, a friction generating member 21 attached to the swinging end of the swinging lever 20 is arranged to face the swinging end. Although not shown in detail, the swing lever 20 has a base supported by a support shaft 20A and can swing. The swinging end has a biasing spring and a semicircle at positions opposing the swinging end. A cam member having a shape is provided. The biasing spring connects the swing end of the swing lever to the transfer belt 6C.
The cam member is a member that swings the swing lever 20 toward the transfer belt 6C against the habit of the biasing spring.

The rotation of the cam member is controlled via a clutch member (not shown). When the transfer roller 9 is separated from the transfer belt 6C, that is, batch transfer as a secondary transfer process is not performed. Sometimes, the friction generating member 21 is brought into contact with the rotating shaft 6A1 of the roller 6A. In this embodiment, the roller 6A by the friction generating member 21 is used.
Is set to a frictional force that applies a load equivalent to the on-axis torque generated when the transfer roller 9 is in contact with the transfer belt 6C, and the rotation shaft 6A1 of the roller 6A is set.
, The movement unevenness of the transfer belt 6C does not occur or the load fluctuation is reduced as much as possible.

Since the present embodiment has the above configuration,
When the image for each color formed on the photoreceptor belt 2 is superimposed and transferred onto the transfer belt 6C, a secondary transfer process is performed using the transfer roller 9, but the transfer roller 9 is transferred to the transfer belt 6C. Until the contact, as shown in FIG. 2, the swing lever 20 maintains the swing state toward the rotation shaft 6A1 of the roller 6A. As a result, an axial torque equivalent to that when the transfer roller 9 contacts the transfer belt 6C by the friction generating member 21 acts on the roller 6A as a load.

On the other hand, when the secondary transfer process is performed,
As shown in FIG. 3, the swing lever 20 swings away from the rotation shaft 6A1 of the roller 6A. For this reason, the friction load from the friction generating member 21 does not act on the rotating shaft 6A1 of the roller 6A, but the contact of the transfer roller 9 causes an on-axis torque equivalent to the friction load by the friction generating member 21 to act. Become. Therefore, the rotating shaft 6A1 of the roller 6A
In this case, the same on-axis torque is generated at both the time when the transfer roller 9 is in contact with and the time when the transfer roller 9 is separated from the transfer roller 9, and the state where the load is hardly changed is maintained. As a result, the transfer belt 6C does not generate uneven rotation of the roller 6A, so that the image transfer timing from the photosensitive belt 2 does not shift. As a result, the images of the respective colors transferred to the transfer belt 6C do not shift each other, and the occurrence of the color shift and the banding can be prevented. In the present embodiment, not only the contact / separation of the transfer roller 9 but also the contact / separation operation of the swing lever 20 with respect to the rotating shaft 6A1 is set in consideration of the contact / separation operation timing of the cleaning device 6E. Next, which is possible
Another example according to the embodiment of the present invention will be described with reference to FIG. FIG. 4 is a block diagram illustrating a configuration for monitoring a change in load due to a deterioration state when the friction generating member 21 illustrated in FIG. 2 is used. In FIG. The number of contact / separation operations is monitored to determine deterioration.

In FIG. 4, the number of contacting and separating operations of the transfer roller 9 is monitored by a counter 22 capable of counting the number of copies.
The counter 22 is connected to the input side of the control unit 23.

The main part of the control unit 23 is constituted by a microcomputer. The above-mentioned counter 22 is connected to the input side via an I / O interface (not shown), and the alarm unit 24 is connected to the output side. .

The control unit 23 registers in advance the number of copies that can be regarded as deterioration of the friction generating member 21, and issues an alarm when the actual number of copies reaches the registered number. As a result, it is possible to prevent the frictional generating member 21 from being deteriorated due to abrasion or the like so that the frictional load on the rotating shaft 6A1 of the roller 6A cannot be properly applied, thereby preventing the load fluctuation of the transfer belt 6C from occurring. I have.

The controller 23 detects, for example, the density at the leading end of the batch-transferred image, instead of using the number of copies as a parameter to determine the degree of deterioration of the friction generating member 21 so that the density is appropriately superimposed. The difference from the density at the time may be determined. In this case, density information at the leading end position is attached to image information at the time of forming a latent image, and the like.
The determination process may be performed by the control unit 23 based on the density information.

[0030]

According to the first aspect of the present invention, there is provided a structure in which a different load is applied to the intermediate transfer body in conjunction with the operation of the transfer roller coming and going, so that the intermediate transfer body has a different load from that during the transfer operation. The rotational load on the drive unit of the intermediate transfer member can be made the same between when the transfer roller is in contact with the body and when it is not. As a result, it is possible to prevent the occurrence of operation unevenness in the drive unit of the intermediate transfer body, and to prevent the occurrence of color shift and banding due to a shift in image forming timing.

According to the second and third aspects of the present invention, as a structure for applying a load, a friction generating member which can be brought into contact with and separated from a rotating member provided in a driving portion of the intermediate transfer member is provided, and the transfer roller is provided with respect to the intermediate transfer member. The rotation load is applied due to friction when not in contact, so it is possible to prevent uneven operation of the intermediate transfer body with a simple configuration, and to prevent color misregistration and banding when transferring images of multiple colors. Occurrence can be prevented.

According to the fourth aspect of the present invention, the structure for applying the load applies a load equivalent to the on-axis torque when the transfer roller contacts the intermediate transfer member. The load acting on the intermediate transfer member hardly changes regardless of the contact state and the non-contact state. Thereby, it is possible to prevent the operation unevenness of the intermediate transfer member due to the load fluctuation and to prevent the color shift and the banding at the time of forming the images of a plurality of colors.

According to the fifth and sixth aspects of the present invention, it is possible to monitor a change in load when a friction generating member is used, thereby preventing a load fluctuation of the intermediate transfer member due to deterioration of the friction generating member. As a result, it is possible to maintain a state in which color misregistration does not occur.

[Brief description of the drawings]

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

FIG. 2 is a schematic diagram for explaining a configuration of a transfer device used in the image forming apparatus shown in FIG.

FIG. 3 is a schematic diagram illustrating one embodiment of the transfer device illustrated in FIG. 2;

FIG. 4 is a block diagram for explaining another example according to the embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Color image forming apparatus which is one of image forming apparatuses 2 Photoreceptor belt 6 Primary transfer apparatus 6A, 6B Roller 6A1 Rotation shaft of drive side roller 6C Transfer belt which forms an intermediate transfer body 6E Cleaning apparatus for transfer belt 9 2 Transfer roller 20 as a secondary transfer device 20 Swinging lever 21 which is one of the members that apply a load 21 Friction generating member that is another one of the members that apply a load 22 Number of copy sheets used for deterioration of a friction generating member Counter 23 Control unit 24 Alarm unit

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2H027 DA42 DA45 DE01 DE07 EA03 EC06 EC09 ED24 EE02 GA30 GB10 HB02 HB07 HB16 2H030 AA01 AA05 AD16 BB42 BB46 BB53 BB54 BB71 2H200 FA04 GA24 GA47 GA50 HA02 HB12 HB12 JA03 JA01 LA24 LA27 LB02 LB09 LB13 PA02 PA10 PA12 PA14 PA27 PB32

Claims (6)

[Claims] 1. A photoreceptor capable of forming an image for each color separation, an intermediate transfer member capable of superimposing and transferring an image for each color formed on the photoreceptor, and a bias device operating at the time of image transfer from the photoreceptor A primary transfer device comprising: a primary transfer device, which is capable of coming into contact with and separating from the intermediate transfer member, and collectively transferring an image superimposed and transferred on the intermediate transfer member to a recording medium such as transfer paper by being in contact with the primary transfer device An image forming apparatus comprising: a secondary transfer device including a transfer roller; and a cleaning device capable of contacting / separating the intermediate transfer member. An image forming apparatus is provided with a configuration for applying a load different from that during the transfer operation in accordance with the image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the load is applied by using a friction generating member that can be brought into contact with and separated from a rotating member disposed in a driving section of the intermediate transfer body. Characteristic image forming apparatus. 3. The image forming apparatus according to claim 1, wherein the friction generating member used for applying the load is brought into a non-contact state when the transfer roller comes into contact with the intermediate transfer body. An image forming apparatus, which is brought into a contact state when the transfer roller is separated from an intermediate transfer member. 4. The image forming apparatus according to claim 1, wherein the load is applied to the image forming apparatus, wherein the transfer is generated when the transfer roller is in contact with the intermediate transfer body. An image forming apparatus, wherein a load equivalent to an on-axis torque of a roller is applied. 5. An image forming apparatus according to claim 2, wherein said friction generating member has a configuration for monitoring a change in load on said transfer roller. 6. The image forming apparatus according to claim 5, wherein a counter capable of counting the number of copies is connected to an input side and a warning unit is connected to an output side as a configuration for monitoring a change in load on the transfer roller. The control unit registers the number of copies to be considered as the deterioration of the friction generating member in advance, and warns the time when the load changes by comparing with the actual number of copies. An image forming apparatus comprising: