JPH08234530A - Driving device for developing unit - Google Patents

Abstract

PURPOSE: To control plural developing units with a small number of electrical control objects by controlling the positions of the developing units with the driving of a solenoid and a spring clutch for stopping at two positions by the presence of energization through the use of one driving device and driving the developing rollers of the developing units by the same driving device. CONSTITUTION: The position of a developing unit 20 is controlled with a solenoid 23 and a two-position stop type spring clutch A24 and at this time, a lever 25 controls the movement of another spring clutch A26 connected to a developing roller, interlocking with the movement of the developing unit 20. In other words, a driving module is composed of the solenoid 23, the spring clutch A24 having two pawls 24a and 24b, the lever 25 and the spring clutch B26. Two cams 22 and 27 are attached to the spring clutch A24 and the first cam 27 rocks the lever 25, to control the rotation of the spring clutch B26. The second cam 22 moves the developing unit 20 back and forth. Thus, the rotation and contact/uncontact of four developing units 20 can be controlled by the ON and OFF control of the solenoid 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color electrophotographic apparatus such as a color laser printer or a color copying machine, and more particularly to a driving device for a developing device.

[0002]

2. Description of the Related Art A conventional drive device for a developing device in a color electrophotographic apparatus uses a clutch to control a developing roller and the like, as disclosed in Japanese Patent Laid-Open No. 61-172174. Further, Japanese Patent Laid-Open No. 4-280272 discloses a structure in which a developing device is brought close to or retracted by using an electromagnetic clutch and a cam. In a monochrome printer, the developing roller, which should have been in constant contact with the photoconductor and rotating together, must be separated from the photoconductor in order to prevent color mixing in a color printer. is increasing. Compared to the two-component development, the one-component development has less objects to be controlled, but nonetheless, electric control means such as a clutch and a solenoid for rotating the developing roller and pressing the developing device against the photosensitive member is required.

On the other hand, there is also a method of rotating the developing device like a ferris wheel to switch the developing device. This is because the power needs to be transmitted only to the developing device in the predetermined position, so the number of clutches and solenoids may be small, but the developing device can be rotated in a very short time between the first color and the second color to set the predetermined position. Therefore, there is a drawback that the drive stopping device becomes large.

[0004]

When a developing device and a photoconductor are separated from each other, or when a clutch or a solenoid is used, in a color printer, it is complicated to provide eight electrical control means for a four-color developing device. It will be larger.

Further, the rotary switching system has a problem in that a driving device capable of performing high-speed and highly-accurate position control is required, and therefore the driving device becomes large.

It is an object of the present invention to provide a developing device driving device for controlling a plurality of developing devices with a small number of electrically controlled objects.

[0007]

SUMMARY OF THE INVENTION The above-mentioned problem is that a single drive unit drives a solenoid and a spring clutch that stops at two locations depending on the presence or absence of energization to control the position of the developing device and at the same time drive the same drive unit. This is achieved by controlling the drive of the developing roller of the developing device by the device.

[0008]

[Action] With a solenoid and a two-stop spring clutch,
The position of the developing device is controlled. At this time, the lever controls the movement of another spring clutch connected to the developing roller in conjunction with the movement of the developing device.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of a color laser printer which is a color image electrophotographic apparatus according to the present invention will be described below with reference to the drawings.

FIG. 3 is a vertical sectional side view of the color laser printer.

The photosensitive belt 1 provided obliquely rotates around the drive guide rollers 2a to 2c at a constant speed.
The photosensitive belt 1 is uniformly charged by the charger 3, and then sequentially exposed by color by the laser beam 4a emitted from the exposure device 4 according to the image signal for each color, and electrostatic latent images corresponding to the respective colors are sequentially formed. It is formed. The position where the photosensitive belt is irradiated with the laser light is the drive guide roller 2 with little displacement.
It is supposed to be in contact with a. Four developing devices 20Y, 20M, 20C, 20K having developers of respective colors
Is biased to the photosensitive belt 1 by the spring 21, but its position is regulated by the cams 22Y, 22M, 22C and 22K.

When printing starts and an electrostatic latent image corresponding to the color of the developing device comes, for example, when an electrostatic latent image of yellow Y comes, the developing device of 20Y moves to a position where it contacts the photosensitive belt 1. At the same time, the developing roller of the 20Y developing device rotates to form a yellow toner image on the photosensitive belt 1. The formed yellow toner image is transferred to the surface of the transfer drum 6 that rotates in synchronization with the surface of the photosensitive belt 1. Similarly, the magenta electrostatic latent image is developed by a developing device of 20M, and the magenta toner image is transferred to the position of the transfer drum 6 to which the previous yellow toner image has been transferred. By repeating this in sequence for cyan and black, a color toner image is formed on the surface of the transfer drum 6. The paper 8 which is a recording medium accumulated in the paper feed cassette 7 is extracted and conveyed by the paper feed roller 9 and is sent to the registration roller 10, where the paper is aligned and the color toner image on the surface of the transfer drum 6 is conveyed with the conveyance timing. After alignment control, it is sent out toward the transfer roller 11.

The transfer roller 11 applies a mechanical pressing force and a transfer electric field from the rear surface of the transfer roller 6 while bringing the fed paper 8 into contact with the transfer drum 6, thereby forming a color toner image on the surface of the transfer drum 6. Transfer to the sheet 8. The transfer roller 11 does not operate in the process of transferring the toner images of the respective colors on the photosensitive belt 1 onto the surface of the transfer drum 6 to form a color toner image. Are separated from each other, and are pushed toward the transfer drum 6 so as to act in the process of completing the color toner image and transferring it to the sheet 8.

The AC static eliminator 14, which is supplied with an AC voltage from the AC static erasing power source to generate an AC corona, neutralizes the electric charge remaining on the back surface of the paper 8 on which the color toner image has been transferred to eliminate the electric charge. The paper 8 is easily separated from the transfer drum 6.

The sheet 8 separated from the transfer drum 6 is sent to a fixing device 15, and a color toner image is thermally fixed on the surface of the sheet 8 while passing through the fixing device 15. The paper 8 on which the color toner image is thermally fixed is discharged onto the paper discharge tray 17 via the paper discharge rollers 16. The belt cleaner 18 cleans the toner remaining on the surface of the photosensitive belt 1, and a blade is used in this figure. The toner scraped off by the blade falls into a waste toner reservoir provided below and is transported to a waste toner container by a transport roller. Further, the drum cleaner 19 cleans the toner remaining on the surface of the transfer drum 6. The drum cleaner 19 is pulled up so that the cleaning action does not work in the process of repeatedly transferring the monochromatic toner image to the surface of the transfer drum 6 to form a color toner image, and after transferring the completed color toner image to the paper 8. It is pressed so as to act on the surface of the transfer drum 6.

FIG. 1 shows a drive module of the developing device 20. 4 drive modules for each developer
As one set, the operation of one drive module will be described here, but other drive modules also perform the same operation. The drive module is a solenoid 23,
A spring clutch A24 having two claws 24a and 24b, a lever 25, and a spring clutch B26. The spring clutch A24 and the spring clutch B26 are connected to a developing motor (not shown) by a gear train to obtain rotational power.

The spring clutch A24 has two cams 22,
27 is attached, the first cam 27 swings the lever 25, and controls the rotation of the spring clutch B26. The second cam 22 moves the developing device 20 back and forth. A developing drive gear 26 is attached to the spring clutch B26, and the developing device 2
It meshes with the gear 20b of 0.

When printing starts, the developing motor starts rotating. However, since the solenoid 23 and the lever 25 are caught by the claws 24a and 26a of the spring clutch, the spring clutch A24 and the spring clutch B26 do not rotate. Only the drive gear of the spring clutch is idle.

When the solenoid 23 is attracted by a signal from the control device, the claw 24a of the spring clutch A24 is disengaged,
The two cams 22 and 27 start rotating. With the rotation of the cam 22, the developing device 20 is pushed out by the spring 21 and comes into contact with the photosensitive belt 1. At the same time, the developing drive gear 26b and the gear 2
0b mesh. Further, the lever 25 is the spring clutch B.
26, the spring clutch B26 rotates, and the developing roller 20a of the developing device 20 starts rotating to develop the electrostatic latent image. The developing drive gear 26b and the gear 20
If the shape of the cam 27 is determined such that the claw 26a of the spring clutch B26 is disengaged after b is engaged, it is possible to prevent abnormal noise such as tooth jump when gears are engaged. When the spring clutch A24 rotates 180 °, the second claw 24b is caught by the solenoid 23 and stops rotating (see FIG. 2).

When the development is completed, the solenoid 23 is opened, disengaged from the second claw 24b, and again the cams 22, 2 are released.
7 starts to rotate. The lever 25 is caught by the claw 26a of the spring clutch B26, the rotation of the spring clutch B26 stops, the rotation of the developing roller 20a also stops, and the developing device 20 separates from the photosensitive belt 1.

As described above, according to the present embodiment, since the rotation and contact / separation of the four developing devices can be controlled by controlling the solenoid on / off, there is an effect that the cost required for the apparatus can be reduced. .

The second embodiment of the present invention will be described with reference to FIG.

In this embodiment, the developing devices 20Y, 20M, 2
0C is a spring clutch A24 that rotates 180 °, and in conjunction with this, shafts 29Y, 29M and 2 with cams 22 and 27 that rotate at a gear ratio of 1/2 with spring clutch A24.
9C, 3 levers 25Y, 25M, 25C, and 3 spring clutches B26Y, 26M, 26C are controlled by a developing drive module. Cams 22Y, 22M, 22C
Are 90 ° offset from each other. A switch 30 is provided on the cam 27M, and the three developing devices 20Y, 20
The switches 30 are turned on at positions where all the M and 20C are separated from the photosensitive belt 1 (see FIG. 5A).

It is assumed that the developing device K is constructed so as to operate as a single module similar to the first embodiment.
This is because the developing device K develops black and is used most frequently, and therefore it is effective to control the developing device K independently.

When printing is started in the 4-color mode, a yellow Y latent image is formed on the photosensitive belt 1. At this time, the solenoid 23 is turned on and the spring clutch A24 rotates 180 °. The cams 22Y and 27Y rotate 90 ° to press the Y developing device 20Y against the photosensitive belt 1. At the same time, the claw of the spring clutch B26Y is disengaged, the developing roller 20b starts rotating, and the latent image is developed (see FIG. 5B). Next, when developing magenta M, the solenoid 23 is turned off. As a result, the cams 22Y, 22M, 22C rotate 90 ° (see FIG. 5C), the developing device 20Y is separated from the photosensitive belt 1, and the developing device 20M is pressed against the photosensitive belt 1. When developing cyan C, the solenoid 23 is turned on again to rotate the cams 22Y, 22M and 22C by 90 ° (see FIG. 5D), separate the developing device 20M from the photosensitive belt 1, and remove the developing device 20C. Press on the photosensitive belt 1. Then, when developing black, the solenoid 23 is turned off again, the cam rotates 90 ° (returning to FIG. 5A), the developing device 20C moves away from the photosensitive belt 1, and the developing device 20K moves. A solenoid (not shown) provided in the drive module is turned on, and the developing device 20K is pressed against the photosensitive belt 1.

When the solenoid 23 is off, the three developing devices 20Y, 20M and 20C are separated from the photosensitive belt 1 and the developing device 20M is exposed depending on the positions of the cams 22Y, 22M and 22C. There is a state where the belt 1 is in contact with the belt 1. This can be determined by whether or not the switch 30 is turned on.

If the solenoid 23 is off and the switch 30 is not on when the power is turned on, it is determined that the magenta developing device 20M is in contact with the photosensitive belt 1 and the developing motor is rotated, The solenoid 23 is turned on and off once, and the magenta developing device 20M is separated from the photosensitive belt 1 to enter the standby state. At this time, the solenoid 23
If the switch 30 does not turn on after being turned on and off once, it is determined that there is some failure and an abnormality such as a serviceman call is displayed.

In the modes other than the four-color mode, for example, in the case of two-color printing of yellow and cyan, the magenta developing device 20M is pressed against the photosensitive belt 1 at a portion where there is no image between the yellow and cyan latent images. Control to skip magenta.

Although the shape of the cam is described as a circle, the same effect can be obtained by cutting a part of the circle.

As described above, according to this embodiment, the rotation and contact / separation of the four developing units can be controlled by the two solenoids and the one switch, so that the cost required for the apparatus can be reduced and the control is simple. There is an effect that an electrophotographic apparatus of various colors can be provided.

Although the black developing device is controlled independently, it is also possible to set the black operating state when the state of the clutch and the cam is as shown in FIG. 5 (a). in this case,
Further, there is an effect that the number of parts can be reduced.

Although the embodiment in which the spring clutch and the cam are used to move the developing device has been described, there is also a method of directly moving the developing device by using the attraction force of the solenoid. But,
A solenoid is large and expensive for moving a developing device having a large mass, which is contrary to the "inexpensive driving device" which is the gist of the present invention.

Although the color printer has been described above, it goes without saying that the present invention can be applied to a color copying machine.

[0034]

As described above, according to the present invention,
It is possible to control contact and separation and rotation of a plurality of developing devices with a small number of control means, and further it is possible to reduce the cost of the electrophotographic apparatus.

[Brief description of drawings]

FIG. 1 is a perspective view of a developing drive module of a color laser printer according to the present invention.

FIG. 2 is a perspective view of a developing drive module of the color laser printer according to the present invention.

FIG. 3 is a vertical sectional view of a color laser printer according to the present invention.

FIG. 4 is a perspective view of another embodiment of the developing drive module of the color laser printer according to the present invention.

FIG. 5 is an operation diagram showing the operation of the cam of the color laser printer according to the present invention.

[Explanation of symbols]

1 ... Photosensitive belt, 6 ... Transfer drum, 11 ... Transfer roller,
13 ... Transfer power source, 14 ... AC static eliminator, 20, 20Y,
20M, 20C, 20K ... Developing device, 22 ... Cam, 23 ...
Solenoid, 24 ... Spring clutch A, 25, 25Y, 2
5M, 25C ... Lever, 26, 26Y, 26M, 26C
... Spring clutch B, 30 ... Switch.

Claims (5)

[Claims] 1. A rotating toner image carrier, an exposure device for forming a latent image according to image information of a color to be printed on the toner image carrier, and a toner image for each color on the latent image. An electrophotographic apparatus having a plurality of developing devices to be formed, a moving means for moving the developing devices in a direction toward and away from the toner image carrier, and a driving means for operating the developing devices, the driving force of the driving means. A driving device for a developing device, characterized in that a connecting device for driving the moving device to bring a desired developing device into contact with and separate from the toner image carrier is provided. 2. A drive unit for a developing device according to claim 1, wherein the connecting means is a cam, a link or the like. 3. The state detecting means for detecting the state of the connecting means according to claim 1, wherein the driving means drives and controls the moving means by detecting color information to be developed and the state detecting means. And the driving device of the developing device. 4. A toner image carrier that rotates, an exposure device that forms a latent image on the toner image carrier, a plurality of developing devices that form a toner image from the latent images, and the developing device that uses the toner. In an electrophotographic apparatus having a moving means for moving the image bearing member in the contacting / separating direction and a driving means for operating the developing device, two or more developing devices are cyclically moved, and the operation of the driving means is performed. A driving device for a developing device, characterized in that it is provided with a connecting means for interlocking with the operation of the moving means. 5. A drive unit for a developing device according to claim 4, further comprising position detecting means for the developing device that moves in a circulating manner.