JPH0561315A - Image forming device - Google Patents

Abstract

PURPOSE:To miniaturize a device by providing a device main body with a developing unit driving source, a developing unit driving and connecting member and a developing unit selective driving device. CONSTITUTION:When an image forming process is started, a motor 12 rotates simultaneously with the rotation of an image carrier 9. An end-face cam 11 rotates on a center shaft 21, and the motor 12 is stopped in the position where a recessed part 11a is matched with the shift member 15 of the developing unit driving/connecting member 40 corresponding to a developing sleeve 6. The shift member 15 pressed against the end face cam 11 by a compression spring 17 is inserted into the recessed part 11, so that a driving and connecting member 13 is engaged with the driving and connecting member 10. In the case where the crests of the lugs are collided with each other and are not engaged, the rotation of a motor 20 rotating simultaneously is transmitted to a gear 16 with the rotations of a gear train 19, center shaft 21, and a center gear 18. Since a shaft 14 for driving a developing unit rotates the driving/connecting member 13, the connecting member 13 and the member 10 are engaged with each other and the developing sleeve 6 is rotated to carry out development. Simultaneously with the end of the development, the motor 20 is stopped and indexing rotation is carried out in the motor 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided with a drive unit provided in the apparatus main body for selectively driving a developing unit suitable for a multicolor image forming apparatus, and is provided with a process cartridge image carrier and a plurality of developing units. Image forming apparatus.

[0002]

2. Description of the Related Art A conventional example will be described with reference to FIG. The figure shows a laser beam printer. Laser optical device 3
The laser light separated and sent from 3 is imaged on the image carrier 9 uniformly charged by the primary charger 34 to form an electrostatic latent image. According to the rotation of the image carrier 9, first, the developing sleeve 6 which is the driven member of the developing device 3 rotates, and the developing sleeves 7 and 8 which are the driven members of the developing devices 4 and 5 are stopped. Therefore, the color toner in the developing device 3 is applied onto the image carrier 9 so that the latent image is developed into the first color. Then, the toner image by the development is transferred onto the transfer material fed from the paper feeding device 35 and wound around the transfer device 36. The residual toner on the image carrier 9 after transfer is removed by the cleaning device 37,
In the repeated image forming process, the next development is performed by rotating only the developing sleeve 7 of the developing device 4. The transfer device 36 repeatedly moves the above-mentioned transfer material to the transfer position, and transfers the next second color in an overlapping manner. Similarly, the third image formation is performed. At that time, only the developing sleeve 8 of the developing device 5 is rotated, the development is performed, and the final transfer is performed. The transfer material on which the toner images of the three colors are superposed and transferred on the same surface is sent to the fixing device 37, and is discharged outside the device after fixing. In the above, the image carrier 9, the primary charging device 34, the developing devices 3, 4, 5,
The cleaning device 37 is detachably attached to the apparatus main body 1 as an integrated process cartridge 2.

[0003]

First, if the process cartridge 2 is provided with the drive switching mechanism for the developing device, the number of drive connection points with the apparatus main body 1 can be smaller than that in the case where the drive switching mechanism is provided on the apparatus main body side. .. There is also a degree of freedom in the drive connection location. However, since the process cartridge 2 has the drive switching mechanism, there is a problem that the cost of the process cartridge 2 which is a replacement part is increased, the external shape is increased, and the weight is increased.

Therefore, when a drive switching mechanism is provided in the apparatus main body 1, the driven members of the process cartridge 2 are brought close to each other in order to connect the drive with each developing device provided on the outer periphery of the image carrier 9. Therefore, the gear of the process cartridge 2 is simply attached to the gear of the main body 1 of the apparatus.
You cannot use a simple mechanism that connects from the mounting direction. In addition to this, a drive switching mechanism for the developing device is also required, which raises a problem of increasing the cost of the entire apparatus and increasing the size of the apparatus due to the volume occupied by both drive switching mechanisms.

[0005]

A first aspect of the present invention is a process cartridge which includes at least a plurality of developing devices arranged on the outer periphery of an image carrier and an image carrier and which is detachably attached to an apparatus main body. And a developing device drive connecting member according to the number of developing devices of the process cartridge, to which a driving force is transmitted from the developing device driving source, and the connecting member and the developing device of the process cartridge. The image forming apparatus includes a developing device selection driving device that selectively connects and disconnects with a driven connection member.

According to a second aspect of the present invention, in a developing device selecting drive device, a center gear having a center axis having a shaft center coinciding with the rotation center of an image carrier as a rotation center, and a developing device connected to the center gear. The drive source and the center gear are engaged with each other so that the rotation center and the center of the driven connection member of each developing device are the same, and the drive gear for driving each developing device connected to the developing device drive connection member and the same axis as the center gear An end face cam rotatably provided at the center, a stop position control means for the end face cam,
The image forming apparatus according to the first aspect of the present invention, which has a cam follower that is arranged coaxially with the drive gear and that engages with the end surface cam and that advances and retracts the developing device drive connecting member to the driven connecting member of the developing device. It is a device.

According to a third aspect of the present invention, the center gear and the end surface cam are provided with one-way clutches having mutually opposite rotational actions on the coaxial center shaft, and the center shaft is connected to a developing device drive source capable of forward and reverse rotation. A developing device selection drive device in which the developing device is driven through a sender gear by one direction rotation of the developing device drive source, and the cam stop position is controlled by the rotation in the other direction to switch the connection of the developing device. The image forming apparatus according to the first aspect of the invention is characterized in that.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIGS. 1 and 2 are horizontal sectional views, and FIG. 3 is a sectional view taken along line AA of FIG. 1 showing a part of FIG. 1 in a perspective view.

An image carrier 9 is arranged in the process cartridge 2, and the developing sleeves 6, 7 of driven members are arranged around the image carrier 9.
8 are provided. The shafts of the developing sleeves 6, 7, and 8 project to the outside of the process cartridge 2 and are provided with driven coupling members 10 at their ends. The driven coupling member 10 is, for example, one member of a dog clutch.

Corresponding to each of the driven connecting members 10 of the process cartridge 2, the apparatus main body 1 also has a drive connecting member 13 which is another member of a clutch that meshes with the driven connecting member 10 so as to be able to come into contact with and separate from the driven connecting member 10. It is provided concentrically.

A developing device selection driving device for selectively connecting the driving connecting member 13 corresponding to each developing device 3, 4, 5 to and from the driven connecting member 10 of each developing device 3, 4, 5 is as follows. It is as follows. A shift member 15 and a gear 16 which are cam followers of an end surface cam described later are fixed to a developing device driving shaft 14 to which the drive connecting member 13 is fixed. The shaft 14 is rotatably supported by the frame plates 1a and 1b of the apparatus body 1 so as to be axially movable and rotatable. The drive connecting member 13, the developing device driving shaft 14, the shift member 15, and the gear 16 constitute a developing device drive connecting unit 40. A compression coil spring 17 is inserted between the frame plate 1b of the apparatus main body 1 and the gear 16 so as to be inserted in the developing device drive shaft 14. Therefore,
The developing device drive connection unit 40 is the process cartridge 2
Is pressed by the spring 17 toward the driven connecting member 10.

A center shaft 21 is provided on the same center as the image carrier 9.
Is rotatably supported, and the end face cam 11 is connected to the shaft 21.
The center gear 18 is fixed to the shaft 21. The end surface cam 11 has a cylindrical outer circumference, and an end surface along the outer circumference is perpendicular to the center shaft 21, and a recess 11a into which the shift member 15 moves and fits is provided at one position of the end surface. A gear 39 is fixed to the end surface cam 11, and a gear train (not shown) meshing with the gear 39 is connected to an output shaft of a motor 12 fixed to the frame plate 1a. As shown in FIG. 3, the center gear 18 meshes with each gear 16,
The tooth width is wide so that meshing is always maintained in the axial movement range of No. 6. A gear train 19 connects between a motor 20 of a developing device drive source mounted between the frame plates 1a and 1b of the apparatus main body 1 and a center shaft 21. The gear train between the motor 12 and the gear 39 includes a notched gear pair.
End face cam 1 which can be freely rotated on the center shaft 21 via the gear train
When 1 is rotated, the concave portion 11a of the end face cam 11 has a position where it coincides with each shift member 15 and a position where it does not coincide with the shift member 15.

When the laser beam printer is in a standby state, the end surface cam 11 is in a position where the recess 11a is not connected to each developing device drive connecting unit 40 as shown in FIG. When the image forming process is started, the motor 12 is rotated in synchronization with the rotation of the image carrier 9 to rotate the end cam 11
3 rotates in the direction of the arrow shown in FIG. 3, and the motor 12 stops at the position where the concave portion 11a coincides with the shift member 15 of the developing device drive coupling unit 40 corresponding to the developing sleeve 6, and the end surface cam 11 also remains stationary. Then, the shift member 15 is pressed against the end surface cam 11 by the compression coil spring 17.
Fits into the recess 11a of the end cam 11, the developing device drive connection unit 40 advances toward the driven connection member 10 coaxial with the developer sleeve 6, and the drive connection member 13 meshes with the driven connection member 10. When the claws of the claws are not in contact with each other due to collision, the rotation of the motor 20 rotating simultaneously or subsequently rotates with the gear train 19, the center shaft 21, and the center gear 18,
Since the rotation is transmitted to the gear 16, the developing device drive shaft 14 rotates the drive connecting member 13, so that when the peaks and the valleys are next matched, the drive connecting member 13 and the driven connecting member 10 mesh with each other, and the developing sleeve 6 rotates. , Development is performed. When the development of the toner of the developing device 3 is completed, the motor 20 is cut off,
The motor 12 is rotated for indexing, and the end cam 11 is connected to the driven connecting member 10 that connects the recess 11a to the developing sleeve 7 of the next developing device 4 and the corresponding developing device driving connecting unit unit 4.
It rotates to a position corresponding to the position of the shift member 15 of 0 and stops. As a result, the drive connecting member 13 facing the driven connecting member 10 of the developing device 6 is disengaged, these members 10, 13 corresponding to the developing device 7 are engaged, and the motor 20 is driven in time with the development of the next color. , Developing sleeve 7
Rotates. Similarly, the developing sleeve 8 of the developing device 5 for the third color rotates.

When the image formation is continued, the recess 11a of the end cam 11 rotates to the position of the developing device drive connecting unit 40 which drives the developing device 3, and the shift member 15 causes the end member cam 11 to move with respect to the subsequent transfer material. It is fitted in the concave portion 11a.

In the present embodiment, the opening / closing mechanism of the opening / closing cover for attaching / detaching the process cartridge of the apparatus main body is operated by the above-mentioned selective drive device and the developing device in a part of the opening / closing operation so that the end face cam 11 is provided with a notch gear. The cam 11 is stopped by the notch when the driving of all the developing devices 3, 4, 5 is released (not shown).

[Second Embodiment] FIGS. 4 and 5 show a second embodiment.
In the first embodiment, one-way clutches are provided on the end cam 11 and the center gear 18 provided on the center shaft 21, respectively, and the rotation of the center shaft 21 is transmitted to the end cam 11 by the rotation of the motor 20 in one direction to control the stop position. A selection is made to connect. In addition, the rotation of the other direction causes the center shaft 2
The rotation of 1 drives the center gear 18 and the gear 16 to drive the developing device connected by the drive connecting member 13 and the driven connecting member 10. In FIG. 4, the concave portion 11 a is the shift member 15
5, the recess 11a is aligned with the shift member 15 in FIG.
The state which the shift member 15 advanced is shown.

According to this embodiment, the motor 12 of the previous embodiment and the gear train including the cutout gear connected to the motor 12 are not required, and the structure is simplified.

[Third Embodiment] FIGS. 6 and 7 show a third embodiment.
In this embodiment, the positions of the end surface cam 11 and the center gear 18 are replaced with those in the previous embodiment, the end surface cam 11 is formed with a convex portion 11b instead of the concave portion 11a, and the compression coil spring 22 is shifted with the gear 16. The shaft 14 between the members 15
The shift member 15 is fitted to the shaft 14 so as to be movable in the axial direction. A compression coil spring 23 for retracting the shaft 14 is provided between the frame plate 1b of the apparatus body and the spring seat 14a fixed to the end of the shaft 14. The shift member 15 in which the convex portions 11b coincide with each other moves forward to compress the spring 22, and the gear 16 is pressed by the spring 22, so that the connecting unit 4
0 is pushed toward the driven connecting member 10 of the process cartridge 2, and the state shown in FIG. 7 is obtained. Convex portion 1 of end face cam 11
The developing device drive connection unit 40 located at a position other than 1b is disconnected by the force of the spring 23 pulling the shaft 14 as shown in FIG. Here, the springs 22 and 23 have a strong force in the extended state, and the spring 22 having a spring constant larger than the spring 23 becomes stronger than the spring 23 when compressed. By using the spring 22, the pressing force is limited when the top of the clutch claw at the tip of the driven connecting member 10 and the drive connecting member 13 collides during the connecting operation.

[Fourth Embodiment] FIGS. 8, 9 and 10 show a fourth embodiment. In the third embodiment, the developing device drive connection unit 40 shown in FIG. 10 is provided on the fixed shaft 26. The shift gear 24 integrated with the shift member 15 is moved toward the process cartridge 2 by the convex portion 11b of the end cam 11 (FIG. 8). A plate-like drive connecting member 27 provided so as to be movable in the vertical direction of the drawing is stopped by a cylinder 28 integrally fixed to the gear 24 and a pin 30 fixed to the cylinder 28 and inserted into the guide hole 29. The connecting member 27 is pushed by a spring 32 inside the cylinder. The connecting member 27 fits into a one-character concave portion 25a provided at the center of the end face of the driven connecting member 25 of the process cartridge 2. It fits by rotation without fitting at the time of connection. A compression coil spring 31 is contracted between the thrust collar 1c in contact with the frame plate 1a and the shift gear 24. Then, except for the convex portion 11b of the end surface cam 11, as shown in FIG.
0 is saved.

[0021]

As described above, according to the present invention, the developing device selecting drive device is provided in the apparatus main body, and the developing device driving connecting member is connected to the driven connecting member of the developing device as a member for performing the selective driving by the selecting driving device. Since they are separated from each other, it is possible to switch and release the plurality of developing devices provided in the process cartridge with one device, and it is not necessary to release the drive connection of the developing devices when the process cartridge is attached and detached. Therefore, the process cartridge has good operability when attached and detached,
The developing device is driven reliably and is reliable.

According to the present invention, a shaft provided with a drive gear with a center gear and a developing device drive gear constantly meshing as a selective drive device is moved by a cam follower engaging with an end face cam coaxial with the center gear to drive the shaft. Since the connecting member is moved back and forth to be brought into contact with and separated from the driven connecting member of the developing device, the structure is simple and the manufacturing cost is low. Further, since the drive gear is meshed around the sender gear, the end cam is provided coaxially with the center gear, and the cam follower is provided coaxially with the drive gear, it is effective in downsizing the device.

According to the present invention, the center gear and the end surface cam are provided with a one-way clutch having a mutually opposite rotational action on a coaxial center shaft, and the center shaft is connected to a developing device drive source capable of forward and reverse rotation. It is equipped with a developing device selection drive device that drives the developing device via the center gear by one-way rotation of the power source and controls the stop position of the cam to switch the connection of the developing device by rotating in the other direction. Since the image forming apparatus according to the first aspect of the invention is adopted, engagement with the developing device to be driven by one driving source and driving of the developing device can be performed. Therefore, the cost is reduced, the number of members is reduced, and the device is downsized.

[Brief description of drawings]

FIG. 1 is a plan view of a first embodiment of the present invention.

FIG. 2 is a plan view of the first embodiment of the present invention.

FIG. 3 is a view taken along the line AA of FIG.

FIG. 4 is a plan view of the second embodiment of the present invention.

FIG. 5 is a plan view of the second embodiment of the present invention.

FIG. 6 is a plan view of the third embodiment of the present invention.

FIG. 7 is a plan view of the third embodiment of the present invention.

FIG. 8 is a plan view of the fourth embodiment of the present invention.

FIG. 9 is a plan view of the fourth embodiment of the present invention.

10 is a partially enlarged view of FIG.

FIG. 11 is a vertical sectional view showing the overall configuration.

[Explanation of symbols]

 10 Driven Connection Member 11 End Face Cam 13 Drive Connection Member

Claims (3)

[Claims] 1. A developing device drive source, which includes a process cartridge that includes at least a plurality of developing devices arranged on the outer periphery of an image bearing member and an image bearing member and is detachably attached to the device body. And the driving force is transmitted from the driving source,
A developing device driving connecting member according to the number of developing devices of the process cartridge, and a developing device selecting driving device for selectively contacting and separating the connecting member and the driven connecting member of the developing device of the process cartridge. Image forming apparatus. 2. A developing device selecting drive device, wherein a center gear having a center axis having a shaft center coinciding with a rotation center of the image carrier as a rotation center, a developing device drive source connected to the center gear, The center of rotation is the same as the center of rotation of the driven connecting member of each developing device that meshes with the center gear, and the drive gear for driving each developing device connected to the developing device driving connecting member and the center gear can rotate about the same axis. A cam follower that is provided coaxially with the end surface cam, stop position control means for the end surface cam, and the drive gear, engages with the end surface cam, and advances and retracts the developing device drive connecting member to the driven connecting member of the developing device. The image forming apparatus according to claim 1, further comprising: 3. The center gear and the end surface cam are each provided with a one-way clutch having a mutually opposite rotational action on a coaxial center shaft, and the center shaft is connected to a forward and backward reversible developing device drive source. It is equipped with a developing device selection drive device that drives the developing device through the center gear by rotating in one direction and controls the stop position of the cam to switch the connection of the developing device by rotating in the other direction. The image forming apparatus according to claim 1.