JPH0690548B2 - Image forming device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus having a plurality of developing devices,
In particular, the present invention relates to an image forming apparatus which can be suitably used as a color electrophotographic copying apparatus or a color recording apparatus for a computer output section. In the following description, a copying machine will be described, but the present invention is not limited to this.

2. Description of the Related Art Conventionally, in a color electrophotographic copying apparatus, in particular, a plurality of developing devices are arranged around one image carrier, that is, a photosensitive member (photosensitive drum) which is usually cylindrical, and selected. It is common to obtain a multi-color or full-color copy by making one developing device operable and the other developing device inoperative.

At this time, in order to prevent the color mixture between the developing devices and the developed image on the photosensitive drum developed by one developing device from being contaminated with the developer of another developing device, each developing device is It is preferable that the developing unit is movable between the developing operation position and the developing non-operation position, and is retracted to the developing non-operation position separated from the photosensitive drum except for the developing device located in the developing operation position adjacent to the photosensitive drum.

Even in such a color copying apparatus, it is preferable that the number of times of movement of each developing device is as small as possible so that the developer (toner) in the developing device is not scattered by the vibration generated by the movement of the developing device.

Considering the above points, regarding the movement of the developing device, one selected developing device is arranged at the developing position, and all the other developing devices are retracted to the developing inoperative position separated from the photosensitive drum. When one developing device existing in the developing inoperative position is selected, the selected developing device is first moved to the developing operating position, and then the developing device currently in the developing position is moved to the developing inoperative position. It is preferable to evacuate. Further, the movement of each developing device is usually automatically performed by a driving means provided with a driving source. In particular, it is preferable that the movement of each developing device is mechanically linked so that only one developing device can be reliably positioned at the developing position with a simple mechanism.

However, according to such an electrophotographic copying apparatus,
Since one developing device is always placed in the developing position,
There was a problem when the photosensitive drum was scratched when the photosensitive drum was pulled out from the main body of the apparatus for maintenance of the machine in the axial direction or when the developing device at the developing position was taken out of the main body of the apparatus.

Accordingly, the object of the present invention is to have a structure in which one developing device is always arranged in the developing position, but to move all the developing devices to the developing inoperative position as needed. If the image carrier is damaged when the image carrier is pulled out axially from the machine body for maintenance management of the machine or when the developing device at the developing position is taken out from the machine body A forming device is provided.

Means for Solving the Problems The above object is achieved by the image forming apparatus according to the present invention. In summary, the present invention relates to an image bearing member carrying an electrostatic image, first and second developing units for developing the electrostatic image on the image bearing member, and a mechanical structure for the first and second developing units. And a moving means for moving the developing device mechanically interlocked with movement of one developing device from the developing position to the developing inoperative position and moving the other developing device from the developing inoperative position to the developing position. And a manual operation means for manually moving the developing device at the developing position to the developing inoperative position, wherein the interlocking device is configured so that the moving force of one developing device by the moving device is the other. To the developer of
The image forming apparatus is characterized by having a one-way drive transmission member that does not transmit the moving force of one developing device by the manual operation means to the other developing device.

Next, an embodiment of the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

FIG. 2 is a schematic partial sectional view of an electrophotographic copying machine embodying the present invention, and particularly shows a multi-color electrophotographic copying machine equipped with two developing devices.

In this embodiment, the latent image carrier having a cylindrical shape, that is,
The electrophotographic photosensitive drum 1 is rotatably provided, and a device for an electrophotographic process is arranged around it. Briefly described, the primary charger D is located almost directly above the photosensitive drum 1, the developing device 2 is located on the right side of the photosensitive drum 1 in FIG.
3. A cleaning device C on the left side portion of the transfer discharger T and the photosensitive drum 1 in FIG.
Are placed. An optical system (not shown) is arranged above the electrophotographic copying machine, and the original image is exposed on the photosensitive drum 1 at the exposure section E located between the primary charger T and the developing device 2. Configured to project onto. Further, a light source L for erasing the residual charge on the photosensitive drum 1 is provided between the primary charger D and the cleaning device C.

The operation of the color electrophotographic copying machine configured as described above will be briefly described.

The photosensitive drum 1 starts rotating in the direction of the arrow when the operation starts, and is charged by the primary charger D. The charged photosensitive drum 1 further rotates, and the exposed portion E is moved by the action of the optical system.
The light image is slit-exposed to form an electrostatic latent image of each color on the photosensitive drum 1. The latent image on the photosensitive drum 1 is then brought into rotation by the rotation of the photosensitive drum 1 to a developing area where the developing devices 2 and 3 are arranged. The electrostatic latent image on the photosensitive drum 1 is visualized as a toner image by any one of the developing devices 2 and 3.

The toner image on the photosensitive drum is transferred onto the transfer material P fed from a paper feeding device (not shown) in the transfer area where the transfer discharger T is arranged. The transfer material P carrying the toner image is then conveyed to a fixing device (not shown) and fixed.

The photosensitive drum 1 is subjected to the actions of the cleaning device C and the light source L and then performs the next image forming process again.

Next, the operation of the developing devices 2 and 3 will be described in more detail. In the present embodiment, it is assumed that the first developing device 2 contains a color toner developer such as red and the second developing device 3 contains a black developer.

The developing devices 2 and 3 are respectively separated by the developing device moving means 4 and 5 into a developing position in which the developing device is in close proximity to the photosensitive drum 1 to perform a developing operation and a developing inactive position in which the developing device is separated from the photosensitive drum 1 and does not perform a developing operation. It is configured to be movable between. In this embodiment, the developing device moving means is cam means 4 and 5, which will be described later in detail. In FIG. 2, the first developing device 2 is in the non-developing position and the second developing device 3 is in the developing operating position. In this embodiment, the arrangement state of the developing device is set as a reference state. That is, black development is possible in the reference state.

The state of the developing device shown by the broken line in FIG. 2 shows a state in which the first developing device 2 containing the color toner is selected.
The developing device 2 moves to the developing position, the second developing device 3 moves to the retracted position,
That is, it moves to the non-developing position.

FIG. 3 shows one embodiment of the first cam means 4 and the second cam means 5.

The first cam means 4 extends between the body side plates 6 and 7, and
Cam shaft 4 rotatably supported on the side plates 6 and 7 by 3, 43
Having one. A cam member 42 is fixed to the center of the cam shaft 41, and a gear 44 is provided with a set screw 45 at the shaft end protruding from the side plate 7.
Can be installed at.

Similarly, the second cam means 5 has a cam shaft 51 extending between the body side plates 6 and 7 and rotatably supported on the side plates 6 and 7 by bearings 53 and 53. A cam member 52 is provided at the center of the cam shaft 51.
Is fixed, and the gear 54 is attached to the shaft end protruding from the side plate 7.
It is attached via a one-way rotating clutch 55 which constitutes a manual operation means which will be described in detail later. The gears 44 and 54 have the same number of teeth and are meshed with each other via the idler gear 8.
Further, a handle 56 is attached to the other end of the cam shaft 51 protruding from the side plate 6.
Is provided.

A driving force from a driving source (not shown) is transmitted to the driving gear 54 of the second cam means 5 via the clutch means 9.

The clutch means 9 includes a shaft 71 implanted in the side plate 7 and the shaft 71.
And an input sprocket 92 and a gear 91 rotatably supported by bearings 93 and 94. Input sprocket
A driving force is transmitted to the 92 from a driving source through a chain (not shown), and the gear 91 meshes with the gear 54 of the second cam means. For reasons that will be described later, the number of teeth of the gear 91 is the same as that of the gear 54.

The gear 91 and the sprocket 92 are arranged adjacent to each other on the bearings 93 and 94, and the clutch spring 95 is wound around the body of the gear 91 and the sprocket 92 so as to straddle each other. Furthermore,
On the outside of the clutch spring 95, there is a control ring with a claw on the outer circumference.
96 is installed and the input sprocket 92 of the clutch spring 95
One end on the side is connected to a part of the control ring 96, and the other end is connected to the gear 91.
It is integrally attached to. Therefore, when rotation in a predetermined rotation direction is transmitted to the sprocket 92, if the control ring 96 is constrained to be unable to rotate, the clutch spring 95 is fitted loosely in the body of the gear 91 and the body of the sprocket 92. Therefore, the rotational force of the sprocket 92 is not transmitted to the gear 91. On the other hand, if the restraint of the control ring 96 is released and the control ring 96 is made rotatable, the clutch spring 95 is fitted tightly and tightly to the body portions of the gear 91 and the sprocket 92, and the rotational force of the sprocket 92 is transmitted to the gear 91. .

The movement of the control ring 96 is controlled by the solenoid 97 and the swing lever 98. Two claws (96a, 96b) on the outer periphery of the control ring are provided, and when the solenoid 97 is not energized, the swing lever 98 is brought into contact with the first claw 96a by the return spring 99.
The rotational force of the input sprocket 92 is not transmitted to the gear 91, and the first and second cams 4 and 5 are stopped and held at the positions indicated by the solid line in FIG. 2 (reference state).

In order to obtain a color copy of the first developing device 2, the solenoid 97 is activated only when the color copy command is issued and the copying operation starts, and the swing lever 98 is the first pawl of the control ring 96. The position deviates from 96a and becomes the position of the broken line. As a result, the clutch spring 95 is in a tightened state, the rotational force from the input sprocket 92 is transmitted to the gear 91, and rotation is started. The second pawl 96b of the control ring 96 comes into contact with the swing lever 98 when the gear 91 has rotated about 1/2. As a result, the clutch spring 95 is fitted in the body portions of the gear 91 and the sprocket 92 in the loosely attached state, and the rotational force of the sprocket 92 is not transmitted to the gear 91. Therefore, the gear 91 is stopped, and the first and second cams and the first and second cams are stopped.
The developing units 2 and 3 are located at the positions indicated by broken lines in FIG.

The drive source is stopped with the end of the copy operation, but the solenoid 97 is de-energized before that. Therefore, swing lever 98
Is released from the second pawl 96b by the force of the return spring 99. As a result, the clutch spring 95 is again fitted into the body of the sprocket 92 and the gear 91 in a tightly tightened state, the rotational force of the sprocket 92 is transmitted to the gear 91, and the gear 91 moves to the first position.
The pawl 96a rotates until it comes into contact with the swing lever 98 and returns to the original position (the state shown in FIG. 3).

As described above, when the spring clutch means 9 is used and the number of teeth of the gear 91, the gear 54, and the gear 44 is made equal, the relative relationship between the control ring 96 and the first and second cams 4, 5 does not always change. , You can get convenient results.

However, at the reference position (solid line position in FIG. 2), for example, when the photosensitive drum 1 is pulled out to the front side of the drawing for maintenance, or when the developing device 3 is pulled out to the front side of the drawing, The developing device 3 and the drum are so close to each other that the photosensitive drum 1 may be damaged. Further, in order to make the size of the gap between the developing rollers 2a, 3a provided in each developing unit 2, 3 and the surface of the photosensitive drum 1 a predetermined value, a contact roller with a guaranteed gap is attached to both ends of the developing roller. If
There is no gap between the photosensitive drum 1 and the abutting roller, and the surface of the photosensitive drum 1 is extremely easily damaged.

According to the invention, a handle 56 is provided on the other end of the shaft 51 of the second cam means 5.
By operating the grip 56, only the second cam means is driven, and the second developing device 5 is temporarily moved to the developing inoperative position where it is separated from the photosensitive drum 1, that is, the position indicated by the broken line in FIG. It is constructed to be vulnerable.

In order to facilitate such manual operation, a manual operation means is provided according to the present invention. In the embodiment shown in FIGS. 1 and 3, the manual operating means is a gear 54 as shown in FIG.
A one-way rotating clutch 55 is provided between the cam shaft 51 and the cam shaft 51. Drive (rotational force in the direction of arrow A) from the input sprocket 92 side is transmitted to the camshaft 51 by the clutch 55, while
When the gear 54 is stopped, move the handle 56 at the tip to the arrow A in the same direction.
Even if it is rotated to the side, the rotational force is not transmitted to the gear 54 side via the shaft 51.

Therefore, when the second developing device 3 is stopped close to the photosensitive drum 1, the handle 56 can be rotated in the direction A of FIG. 1 to retract the second developing device 3 to the non-developing position. . handle
56 is the position in which the developing device 3 is most retracted after about 1/2 rotation.

Next, if the retracted second developing device is left as it is,
The relationship between the first developing device 2 and the second developing device 3 starts to move from the development non-operating position, and the developing devices are not arranged in different operating positions as shown in FIG.
Therefore, after the photosensitive drum or the developing device is taken out and a predetermined procedure is performed and the photosensitive drum or the developing device is mounted at the initial position, the second developing device 3 needs to be returned to the original developing operation position. That is, it is necessary to manually rotate the handle 56 in the direction of the arrow A by about 1/2 turn to rotate the cam to the cam position shown by the solid line in FIG. Of course, the direction opposite to the arrow A direction is a one-way rotating clutch.
Since it has 55, it cannot be turned.

FIG. 4 shows another embodiment of the manual operation means that can simplify the manual operation of the developing device 3.

According to the present embodiment, the one-way rotating clutch 55 is not provided between the cam shaft 51 and the gear 54 as in the above embodiment, but a pin 57 is provided instead, and the gear 54 has a substantially anti-circular shape. Groove 58 is formed. The pin 57 is set in the groove 58 of the gear 54 described above. The pin groove 58 is sized to allow the pin 57 to rotate freely, and the pin 57 is configured to rotate 1/2.

If the gear 54 rotates in the direction of arrow A and then stops, the pin 57 on the camshaft 51 is in contact with one wall a of the pin groove 58 as shown in the figure. At this time, the cam 52 is at the position indicated by the solid line (that is, the developing device 3 is at the developing operation position),
When the handle 56 is rotated in the direction of arrow A, the pin 57 moves into the pin groove 58.
To the position of the broken line, and rotates to the position of the broken line which hits the wall b of the pin groove. Accordingly, the cam 52 rotates to the position indicated by the broken line, and the developing device 3 is retracted to the non-developing position. Next, when returning to the original position, the handle 56 can be returned to the original position by rotating it in the opposite direction (arrow B direction). Further, in the present embodiment, it is not necessary to operate the handle 56, and once the other developing device, that is, the first developing device 2 in the present embodiment, is selected, the gear 54 is rotated by the drive source and the pin groove 58 The wall a comes into contact with the pin 57.
Then, when the second developing device 3 is selected, both the first and second developing devices are returned to their original reference positions.

In the above embodiment, since the developing device 2 is separated from the photosensitive drum 1 in the reference state, no manual operation means is provided in the first cam means 4, but when it is not in the reference position, that is, the broken line state in FIG. In order to enable the development 2 or the removal of the photosensitive drum 1 in step 1, the first operation means 4 can also be provided with a manual operation means.

As described above, according to the present invention, the one-way rotating clutch is interposed between the cam shaft and the drive gear, or the play is always provided between the cam shaft and the drive gear. One is that the developing device at the developing position can be manually moved to a retracted position away from the drum.

In the above embodiment, since two developing devices are used, only one spring clutch means 9 is used for explanation. However, each cam shaft is provided with a spring clutch means, and one spring clutch means is used as a developing device. May be set as the reference position while the other spring clutch means is set as the reference position when it is in the developing device retracted position. The reference position here means the state of the output side, that is, the state of the developing device when the rotational force of the rotary drive source is input to the spring clutch when the solenoid of the spring clutch means is not energized. Even when the number of developing devices is three or more, the spring clutch means is provided corresponding to each developing device, and the reference position of one specific developing device can be set to the developing position.

The image forming apparatus according to the present invention mechanically interlocks the movements of the first and second developing devices by the interlocking device, so that only one developing device can be reliably developed with a simple mechanism. It is possible to position the first position and the second position by providing the interlocking device with a one-way drive transmission member.
It is possible to position both the first and second developing devices to the non-developing position without particularly releasing the mechanical interlocking of the developing devices. It has an effect that the image carrier is not damaged when the image carrier is taken out in the axial direction or when the developing device at the developing position is taken out from the apparatus main body.

[Brief description of drawings]

FIG. 1 is a perspective view of a drive portion of an embodiment of a cam means for contacting and separating a developing device. FIG. 2 is a schematic sectional view of an embodiment of the image forming apparatus. FIG. 3 is a cross-sectional view of the drive portion of the cam means of FIG. 1 for contacting and separating the developing device. FIG. 4 is a perspective view of a drive unit of another embodiment of the cam means for bringing the developing device into and out of contact. 1: photosensitive drum 2, 3: developing device 4, 5: cam means 9: clutch means 41, 51: cam shaft 42, 52: cam 44, 54: drive gear 55: one-way rotation clutch 57: pin 58: pin groove

Claims (1)

[Claims] 1. An image carrier for carrying an electrostatic image, first and second developing devices for developing the electrostatic image on the image carrier, and mechanically connected to the first and second developing devices. Then, an interlocking unit that mechanically interlocks with the movement of one developing unit from the developing position to the developing inoperative position to move the other developing unit from the developing inoperative position to the developing position, and a moving unit that moves the developing unit. In the image forming apparatus having the: Tell the vessel,
An image forming apparatus comprising a one-way drive transmission member that does not transmit the moving force of one developing device by the manual operation means to the other developing device.