JPH10142932A - Electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an operation system where the mark of the toner image of each color is formed on a carrying belt as the alignment control of a color image, and also the life of each renewal part is used at most by eliminating consumption by working only a part necessary for forming a black image and stopping the part necessary only for forming a color image when a black monochromatic image is formed. SOLUTION: At the time of forming the color image, transfer paper is pulled out from a paper feeding cassette 40, and is guided on the side of an upper resist roller 42 by a passage switching can 3, and is electrostatically attracted to the carrying belt 35, and receives the toner image from each photoreceptor, and is guided to a fixing unit. At the time of forming the black image, the carrying belt 35 is retreated at the position of a broken line, and is moved to the position (the position of the broken line) where a transfer roller 4, a pair of second resist rollers 5, guide plates 13, 14, 15 and 16 actuate on the photoreceptor for black. In this state, the transfer paper is pulled out from the paper feeding cassette 40, and passes carrying rollers 2b, 2c and 2d and is fed out by the second resist roller 5, and is fed in between the transfer roller and the photorecepter for black.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus, and more specifically, to form a full-color image by arranging image forming units including photoreceptors for respective colors in series and sequentially superimposing the obtained toner images. The present invention relates to an electrophotographic apparatus such as a printer and a copying machine.

[0002]

2. Description of the Related Art A so-called tandem type color electrophotographic system in which a plurality of image forming units are arranged in series is one of the following.
There is a great feature that a color image can be generated at high speed as compared with the method using one photoconductor. On the other hand, in many cases, a color electrophotographic apparatus outputs a black image at the same time as outputting a color image. This is because documents generally used in offices are overwhelmingly monochromatic black documents.
In particular, a printer connected to a personal computer sometimes outputs a black image and a color image in a mixed manner.

Here, the conventional color apparatus has a drawback in that even when an image of only black is formed, the same mechanical operation as that of forming a color image is performed, and unnecessary parts are operated and consumed during black formation. Was. A photoreceptor, a conveyor belt, a charging device, a developing device, a cleaning device, and the like disposed around the photoreceptor are the life components. On the other hand, as a tandem-type issue,
There is a difficulty in the alignment of the image between the colors, and as a control means for the alignment, a position mark of each color is formed on the conveyor belt with a toner image, the amount of positional deviation is detected by a detector, and the position of the image writing position is detected. There has been proposed a method of correcting a position shift by performing correction and rotation control of a drive motor.

In Japanese Patent Application Laid-Open No. Hei 5-341617 (color image forming apparatus), a color image forming section is composed of an intermediate transfer member for superimposing a three-color image forming section and a toner image, and a separate black image forming section is provided. When forming a color image,
An image transfer method is described in which an image is transferred at two transfer sections and only a black image is transferred by bypassing a conveyance path when a black image is formed.

[0005]

As described above, an electrophotographic apparatus for forming a full-color image often prints only a black image. At this time, a unit which is not necessary for forming a black image also operates. It hasten the replacement of life components.

Further, in the invention described in Japanese Patent Application Laid-Open No. 5-34167, a mechanism for evacuating the transfer section and the like can be configured without necessity. However, it is difficult to prevent image displacement between the color unit and the black unit. In addition, the use of an intermediate transfer member causes a problem that image sharpness is poor.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances. As a color image alignment control, a toner image mark of each color can be formed on a conveyor belt, and a black monochrome image can be formed. When forming an image, only the parts necessary for black image formation are activated, and the parts necessary only for color image formation are stopped, eliminating wear and providing an operation method that maximizes the life of each replacement part. It was made for the purpose of.

[0008]

According to a first aspect of the present invention, a plurality of image forming units including a photoreceptor and having different colors are arranged in series, and a toner image is sequentially transferred onto transfer paper conveyed by a conveyor belt. An electrophotographic apparatus for forming a full-color image, wherein a toner image mark for detecting a color shift is formed on the transport belt in order to detect and correct a color shift at the time of forming the full-color image. In the case of forming a full-color image, the transfer of the toner color is performed by adsorbing a transfer belt that spans a plurality of image forming units, and the transfer belt is evacuated and formed with the transfer belt when forming a single black image. Is characterized in that an image is transferred by another transfer device.

According to a second aspect of the present invention, in the first aspect of the present invention, when a black single-color image is formed, only the black image forming section operates, and the image forming sections stop for other colors. It is.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a transport belt for transporting a sheet during color formation and transferring a toner image to the sheet has a length extending over the entire image forming portion of each color, and a toner image for alignment is provided. When a color image is to be formed, transfer paper is adsorbed onto a transfer belt to transfer and transfer the image.When forming a black image, the transfer unit is evacuated from the image forming unit. The toner image is provided to the black image forming unit, and the toner image is transferred to transfer paper. Also,
At the time of black image formation, the photoreceptor of the image forming unit other than black and components around the photoreceptor are stopped to prevent abrasion and deterioration.

FIG. 2 is a view showing the entire configuration of a conventional tandem type full-color electrophotographic apparatus on which the present apparatus is mounted. Are arranged. The four color forming units are yellow (symbol Y), magenta (symbol M), cyan (symbol C), and black (symbol K), each having the same configuration, and differing only in toner color. . The configuration is such that the photosensitive drum 1 (Y,
A uniform charging potential is applied to the surface of the M, C, K) by a charger 30 (Y, M, C, K), and a latent image is formed by a writing unit 31 (Y, M, C, K) using laser optics. Then, a toner image is formed by the developing device 32 (Y, M, C, K), and a toner image is formed on a sheet by the transfer device 33 (Y, M, C, K). The toner remaining on the surface of the photoconductor after the transfer is cleaned and collected by the cleaning 34 (Y, M, C, K). The paper is sent out one by one from a paper feed cassette 40 by a paper feed roller 41, and a pair of registration rollers 42.
Are supplied to the transport belt unit at the same time. The transport belt 35 includes a driving roller 36 and a driven roller 37.
Is driven and transported at a constant tension. The transfer paper adsorbed on the conveyor belt 35 by the static electricity is Y, M, C,
After the four color toners are transferred by the transfer of the K color, a full color image is formed, the toner is separated from the conveyance belt, and passes through the fixing roller 43 and the pressure roller 44 to be fixed. In addition, the charge remaining on the surface of the transport belt 35 is removed by the static eliminator 38 and the surface is cleaned by the cleaning 39 in preparation for the next image formation. Reference numeral 45 denotes a position shift sensor, which forms a pattern of each color on the conveyor belt 35 when detecting the amount of position shift, detects these positions with a reflection type photosensor or a transmission type photosensor, and detects a color shift between the colors. Read.

FIG. 1 is a diagram showing the construction of a main part of an embodiment of the present invention. In FIG. 1, a conveyor belt 35, a transfer roller 4, a second registration roller pair 5, and a guide are shown. Regarding the plates 13, 14, 15, and 16, solid lines indicate positions when a color image is created, and broken lines indicate positions when a black image is created. When forming a color image, the transfer paper
As shown in FIG. 1, the toner is pulled out from the photosensitive member by a transfer switch (not shown). The image is received and guided to a fuser. When forming a black image, the transport belt
In the figure, at a position away from the photoconductor in the right direction (the position indicated by the broken line)
Then, the transfer roller 4, the second pair of registration rollers 5, and the guide plates 13, 14, 15, and 16 move to the positions (the positions indicated by broken lines) where they act on the black photoconductor (1K). In this state, the transfer paper is pulled out by the paper supply cassette 40, and is guided to the left in the figure by rotating the passage switching cam 3 in the direction of arrow A, and passes through the transport rollers 2b, 2c, and 2d. The paper is fed between the transfer roller and the black photoconductor 1K at the timing of sending by the two register rollers 5. By applying a bias potential to the transfer roller 4, a black image is transferred and guided to a fixing device.

FIG. 3 is a diagram showing marks and detection sensors used for the alignment of each color image. In the alignment mode, each image forming unit causes the positional shift detection marks 18a, 18b, which are toner marks of a fixed pattern, to be formed. Is formed on the conveyor belt 35, and its position is detected by the position detection sensors 19a and 19b provided at both ends facing the conveyor belt 35, and the vertical direction of the image is calculated by arithmetic processing.
The shift amount such as the lateral direction and the inclination is obtained, and the start timing of the image writing, the inclination correction of the writing scanning system, the control of the rotation speed of the drive motor, and the like are performed so that the image of each color is formed at the corresponding position. I do. For this purpose, all four color marks need to be formed on the same belt, and the transport belt must extend over all the photoconductors.

FIG. 4 is an exploded view showing the structure of the transport belt and the transfer roller. The transport belt 35 is stretched between a driving roller 36 and a driven roller 37, and is assembled by transfer belt supporting side plates 21a and 21b. It becomes three-dimensional. Inside this,
The bracket 20 to which the transfer units 33Y, 33M, 33C, and 33K and the displacement detection sensors 19a and 19b are attached is also assembled. The driven roller 37 is supported by the elongated hole 24, and tension is applied to the belt by a spring (not shown). The transfer belt assembly is provided on the transfer unit side plate 2.
The guide holes 2a and 2b support the guide holes 27 and 28 so that the guide holes 27a and 28b can move obliquely. Transfer unit side plate 22a,
22b is fixed to the apparatus main body. On the other hand, transfer roller 4, second registration roller 5, guide plates 13, 14, 1
Reference numerals 5, 16 form an assembly by transfer roller side plates 29a, 29b, and support shafts 50a, 50b provided on both outer sides of the side plates.
Can be rotatably supported by a circular hole 5 of the transfer unit side plate.
2 supported.

The drive roller input gear 25 is mounted on the shaft of the transport belt drive roller, and engages with a drive gear (not shown) provided on the main body structure only when outputting a color image to obtain a driving force. Further, the registration roller input gear 51 engages with the registration roller driving gear 26 when a black image is output, and conveys the transfer paper. The registration roller drive gear 26 is driven by the main body structure. The transfer roller 4 is rotated by being driven by the photoreceptor or rotated by being driven by a gear by the photoreceptor (a gear on the left side of the transfer roller is engaged with a gear provided on the photoreceptor. Do).

The boss 55 of the swing arm 53 is connected to the support shaft 50.
b, the swing arm 53 is driven to swing by a motor 58, a worm 57 and a gear 56. A guide hole 54 is provided in the swing arm, and the guide hole 54 is engaged with the shaft of the transport belt driving roller 36 to move the transfer belt assembly along the guide holes 27 and 28. With this configuration, the movement of the transfer belt assembly and the swinging of the transfer roller assembly can be simultaneously performed by the motor 58, so that the transfer device can be switched between color image formation and black image formation, and paper conveyance can be performed. Road switching can be easily performed.

FIG. 5 is a view for explaining an embodiment of a drive section of an image forming section. In this embodiment, an independent drive motor is provided for each photosensitive member. In this case, each photoreceptor is driven by a drive motor 61 (Y, M, C, K) via a coupling 60 (Y, M, C, K) for absorbing axis deviation. In this case, all the motors are driven at the time of forming a color image, and only the black motor is driven at the time of forming a black image, so that the image forming units for other colors can be stopped.

FIG. 6 is a diagram for explaining another embodiment of the driving section of the image forming section. In this embodiment, all the photosensitive members are driven by one driving motor 69. The rotation of the motor 69 is controlled by the driving pulley 68, the toothed belts 65, 66, 67 and the pulley 64 (Y, M, C, K).
And the continuous clutches 62Y, 62M, 62C
Is transmitted to the photoreceptor via the coupling 63.

FIG. 7 is a view for explaining an example of the construction of the continuous clutch. In this example, a receiving portion 72 having a groove formed in a conical-shaped oval portion is provided on the photoreceptor shaft 70 side, and a pulley shaft 71 is provided.
On the side, a driving portion 73 having a groove formed in the conical toe portion is provided, and the driving portion 73 is slidable in the direction of arrow B with respect to the shaft 71, and in the rotating direction, a pin provided on the shaft and a driving portion are provided. The rotation is regulated by the groove provided. The drive unit is urged leftward in the figure by a spring 75 against a stopper 76. The drive unit 73 is provided with a groove 74, in which a U-shaped arm 77 provided on a rotatable control shaft 78 is provided.
And the rotation of the control shaft 78 enables the continuation of the clutch. This type of continuous clutch is shown in FIG.
It is used for driving C, and the coupling for the black photosensitive member does not need to be able to be continued.

[0020]

【The invention's effect】

According to the first aspect of the invention, in a full-color device of a type in which a plurality of photoconductors are arranged (tandem type), a mark for detecting a positional shift is formed on a transport belt in order to correct a positional shift of an image between respective colors. However, it is effective to detect the shift amount. For this reason, the transport belt needs to extend over all the photoconductors. On the other hand, the conveyor belt also needs image transfer performance and is a part that needs to be replaced depending on its life.If the conveyor belt is operated even when creating a black image, it will cause the same damage as when creating a color image. The belt needs to be replaced early. According to this configuration, when forming a black image, the transfer belt is retracted and the transfer roller is used instead, so that the frequency of replacing an expensive and large transfer belt can be reduced.

According to the second aspect of the invention, the photosensitive member, the charger, the developing device, and the cleaning unit in the image forming unit are replacement parts having the same life as the transport belt. When forming a black image, an image of another color is formed. The operation of the unit increases the replacement frequency, which is not preferable. When an independent drive motor is provided for each image forming unit, a black-only motor is driven.When a single motor is used to drive each image forming unit, a non-black motor is driven via a continuous clutch. By shutting off the drive of the unit, it is possible to prevent consumption by operations other than the black image forming unit, and to reduce the frequency of replacement of replacement parts.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram for explaining an embodiment of an electrophotographic apparatus according to the present invention.

FIG. 2 is a diagram showing an overall configuration of a conventional tandem type full-color electrophotographic apparatus to which the present invention is applied.

FIG. 3 is a diagram illustrating a mark and a detection sensor used for alignment of each color image.

FIG. 4 is an exploded view showing a configuration of a transport belt unit and a transfer roller unit.

FIG. 5 is a diagram illustrating an example of a driving unit of the image forming unit.

FIG. 6 is a diagram illustrating another embodiment of the driving unit of the image forming unit.

FIG. 7 is a diagram for explaining a configuration example of a continuation clutch.

[Explanation of symbols]

1 (Y, M, C, K) photosensitive drums, 2a to 2d transport rollers, 3 path switching cams, 4 transfer rollers, 5 second registration roller pairs, 7 to 16 paper guide plates, 17 …
Transfer roller rotation fulcrum, 18a, 18b: misalignment detection mark, 19a, 19b: misalignment detection sensor, 20
... Detection sensor brackets, 21a, 21b ... transfer belt support side plate, 22a, 22b ... transfer unit side plate, 23
... Round hole, 24 ... Long hole, 25 ... Drive roller input gear, 26
… Registration roller drive gear, 27, 28… guide holes, 2
9a, 29b: Transfer roller side plate, 30 (Y, M, C,
K): charger, 31 (Y, M, C, K): optical writing unit, 32 (Y, M, C, K): developing device, 33 (Y, M, K)
C, K) transfer device, 34 (Y, M, C, K) cleaning, 35 transport belt, 36 drive roller, 37 driven roller, 38 static eliminator, 39 cleaning, 40
Paper feed cassette, 41: paper feed roller, 42: registration roller pair, 43: fixing roller, 44: pressure roller, 45: displacement sensor, 50a, 50b: support shaft, 51: registration roller input gear, 52: round Hole, 53 ... swing arm, 5
4 Guide hole, 55 boss, 56 gear, 57 worm, 58 motor, 60 (Y, M, C, K) coupling, 61 (Y, M, C, K) drive motor, 62
(Y, M, C) ... continuation clutch, 63 ... coupling,
64 (Y, M, C, K): pulley, 65 to 67: toothed belt, 68: drive pulley, 69: drive motor, 70
... Photoconductor shaft, 71 ... Pulley shaft, 72 ... Receiving part, 73 ...
Drive unit, 74: groove, 75: spring, 76: stopper, 77: U-shaped arm, 78: control shaft.

Continued on the front page (72) Inventor Toshiya Sato 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. Person Tomonori Yabuta 10-3 Kitamura, Tottori City, Tottori Prefecture Ricoh Microelectronics

Claims (2)

[Claims] 1. An electrophotographic apparatus in which a plurality of image forming units having different colors including a photoreceptor are arranged in series and a toner image is sequentially transferred onto transfer paper conveyed by a conveyor belt to form a full-color image. In an electrophotographic apparatus in which a toner image mark for detecting a color shift is formed on the transport belt in order to detect and correct a color shift at the time of forming a full-color image, when a full-color image is formed, a plurality of The transfer of the toner color is performed by adsorbing the transfer belt extending over the entire image forming unit, and when forming an image of a single black color, the transfer belt is retracted, and the image is transferred by a transfer device different from the transfer belt. An electrophotographic apparatus, characterized in that: 2. The electrophotographic apparatus according to claim 1, wherein only a black image forming section operates while a black single color image is formed, and the other color image forming sections are stopped.