JP3319226B2 - Drive unit for process cartridge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in an electrophotographic image forming apparatus such as a copying machine or a printer, and is applied to an image carrier and a developing device of a process cartridge detachably mounted to an apparatus main body. The present invention relates to a process cartridge driving device that transmits a driving force from a driving source.

[0002]

2. Description of the Related Art Heretofore, there has been known an electrophotographic image forming apparatus such as a copying machine using a process cartridge. As shown in FIG. 4, the process cartridge integrally includes an image carrier 121 and a charging device 123, a developing device 124, a cleaning device 125, and the like disposed around the image carrier 121, and forms an image. It is detachably attached to the device body. When such a process cartridge 120 is used, replacement of the image carrier 121 and replenishment of the developer in the developing device 124 can be easily performed by replacing the process cartridge 120. There is an advantage that the cartridges can be arranged in a small space by being integrally supported as a cartridge, and the mutual positions can be accurately set. In an image forming apparatus using such a process cartridge, the rotational driving force from a drive motor disposed in the image forming apparatus main body is transmitted with the rotational speed reduced to several tenths and transmitted to each device of the process cartridge. Is driven.

FIG. 5 is a block diagram showing a driving force transmission path of a driving device which transmits driving force from a driving motor to each device in a process cartridge. In this process cartridge driving device,
Drive motor 171 arranged in image forming apparatus main body 100
After the driving force of the process cartridge 120 is reduced by the speed reduction mechanism 174, the driving force is transmitted through the driving force transmission gear 175.
The image carrier 121 is transmitted to the image carrier driving gear 176 supported by the image carrier. Image carrier driving gear 176
The driving force transmitted to the image forming apparatus is further transmitted to the developing roller 126, the charging roller 127, the cleaning brush 128, and a transfer roller (not shown) provided on the image forming apparatus main body side. The transmission of the driving force is provided via a gear 177 meshed with the image carrier driving gear 176 or at an end of the support shaft of the image carrier opposite to the image carrier driving gear. Through the gear 179 that is present.

In the above-described process cartridge driving device, the load of the developing roller driving gear 177 and the charging roller driving gear 178 on the downstream side in the driving force transmission direction acts on the image carrier driving gear 176. I do. When such a load becomes large, the rotation of the image carrier becomes uneven due to the backlash of the meshed gear. Further, in recent years, the gears are plastic gears, and the peripheral speed of the image carrier fluctuates due to fluctuations in the force acting between the gears meshed with each other. As a result, there is a drawback that a formed image has banding (banding) and expansion and contraction of the image. Particularly, in an image forming apparatus in which a laser beam is scanned and a latent image is sequentially formed in a direction perpendicular to the scanning direction, stripe-shaped shading is conspicuous, and when a color image is formed, color unevenness may be caused. Becomes As shown in FIG. 6A, such stripe-like shading occurs in the direction of progress of the process, and is caused by unevenness in the rotation speed of the image carrier at about 15 Hz to 100 Hz. When the unevenness of 20 Hz occurs at a speed of 50 mm / sec, the pitch becomes about 2.5 mm on the image. Further, as shown in FIG. 6B, when a halftone image having a uniform image area ratio of 50% is formed in the progress direction of the process, FIG.
The image density fluctuates by about 1% as shown in FIG.

[0005] As a drive device for a process cartridge which avoids such a problem, Japanese Patent Laid-Open Publication No.
There is one described in Japanese Patent No. 1576. In the apparatus described in this publication, a path for transmitting the driving force from the driving source 181 to the image carrier 121 is provided separately from a path for transmitting the driving force to another apparatus (FIG. 7). There is also disclosed a technique in which a driving source dedicated to an image carrier is provided and driven by a driving force different from that of another device. In each of these technologies, the path for transmitting the driving force to the image carrier is different from the path for transmitting the driving force to the other device, so that a load for driving the other device may cause uneven rotation. However, it is possible to avoid affecting the rotation of the image carrier. Accordingly, it is possible to suppress the occurrence of the circumferential vibration of the image carrier, that is, the unevenness of the circumferential speed.

[0006]

However, the above-mentioned prior art has the following problems. That is, since the path for transmitting the driving force to the image carrier is provided separately from the path for transmitting the driving force to another device, a member for transmitting the driving force and a speed reduction mechanism for each are required, and the The number of components increases significantly, leading to a rise in production costs and an increase in the size of the apparatus. Further, when a drive motor dedicated to the image carrier is used, the problems of increased production cost and an increase in the size of the apparatus become significant.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to minimize an increase in the number of members, to avoid a rise in production costs and an increase in the size of the apparatus, and to provide an image carrier. An object of the present invention is to provide a process cartridge driving device that can rotate at a uniform speed.

[0008]

According to a first aspect of the present invention, there is provided an image carrier of a process cartridge detachably mounted on a main body of an image forming apparatus. A developing device for visualizing the electrostatic latent image formed thereon; and a process cartridge driving device for transmitting a driving force from a driving motor provided in the image forming apparatus main body. Portion of the path for transmitting the driving force supported by the image forming apparatus main body
To have a speed reduction mechanism for transmitting while decelerating the driving force, and one of the driving force transmitting member for transmitting engagement with the driving force and the support portion in said process cartridge, pro
The driving force is transmitted to the portion supported by the process cartridge.
One transmitted member detachably engaged with the first member,
The driving force transmitted to the transmitted member is divided and
Branching means for transmitting the driving force to the drive unit of the process cartridge
And

[0009] According to a second aspect of the invention, in the driving device of the process cartridge according to claim 1, wherein
The branching unit is configured to control the driving force transmitted to the image carrier and the developing force.
It divides the driving force into the driving force transmitted to the device.
You.

The drive motor according to the first aspect of the present invention drives an image carrier and a device included in another process cartridge such as a developing device or a device supported by an image forming apparatus main body. . In addition, the “path for transmitting the driving force” may be constituted by a combination of a plurality of gears, or may use other means such as a pulley and a belt. However, it is desirable to use a combination of gears as described above. In the case of a combination of gears, helical gears, bevel gears, worm gears, and the like can be appropriately combined in addition to spur gears.

The branching means according to claim 1 or 2 branches a path from the middle of the "path for transmitting a driving force" and divides the driving force from a driving source to transmit the divided driving force to a plurality of devices. Things. The branching means meshes a plurality of gears with one of gears constituting a `` path for transmitting driving force '', or fixes a plurality of gears to one rotating shaft in a `` path for transmitting driving force '', and A configuration in which other gears are engaged with each other can be adopted.

In the driving device according to claim 1 or 2, the driving force divided by the branching means is transmitted to two or more devices by being further divided, or after being transmitted to one device. Further, the information may be transmitted to another device.

[0013]

In the driving device for a process cartridge according to the present invention, the driving force from the driving motor is transmitted to the branching means by one path and then divided. One of the divided driving forces is transmitted to the image carrier, and the other driving force is transmitted to a developing device or a charging device. Therefore, a load for driving other devices such as a developing roller does not act on the rotational driving force transmitted to the image carrier, and vibrations due to backlash and fluctuations of the force acting between the meshed gears, that is, The occurrence of rotation unevenness is reduced. Further, since the developing roller, the charging roller, and the like are driven by the driving force branched in the transmission path, even if a slight rotation unevenness occurs due to these loads, the rotation unevenness is transmitted to the upstream branching unit. The vibration component is attenuated while being transmitted to the image carrier side, and has little effect on the rotation of the image carrier. For this reason, the image carrier does not generate rotation unevenness,
It is driven to rotate at a substantially constant speed, and the occurrence of density unevenness and color tone unevenness in the image formed on this surface is avoided.

In this process cartridge driving device, the driving force from the driving motor is transmitted from the driving force transmitting member to the transmitted member supported by the process cartridge via the speed reduction mechanism. After that, the data is divided by the branching means and transmitted through a plurality of routes. Therefore,
A single path is used to transmit the driving force from the drive motor supported by the image forming apparatus main body to the process cartridge, and the process cartridge can be easily attached and detached.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a process cartridge driving device according to the present invention will be specifically described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a laser printer using a process cartridge driving device according to the present invention. The laser printer 1 forms an electrostatic latent image on a photoconductor drum 21 (image carrier) and a laser exposure device 10 that generates image light (laser beam) based on an external signal. A process cartridge 20 on which means for attaching a toner image to a toner image, a paper transport device 30 for feeding a recording medium to a position facing the toner image, and a toner image formed on the photosensitive drum 21 on the recording medium. And a fixing device 50 for fixing the toner image to the recording medium on which the toner image has been transferred. Further, the laser printer 1 has an opening on the upper surface, and an opening / closing lid 60 is hinged to this opening. When the opening / closing lid 60 is opened, the process cartridge 20 is guided by a guide rail (not shown). ) Can be attached and detached.

The housing 2 of the process cartridge 20
A photosensitive drum 21 is rotatably supported in the housing 2 with a part thereof being exposed to the outside of the housing 22. The photoreceptor drum 21 has a photoreceptor layer on the outer peripheral surface, and can form an electrostatic latent image on the peripheral surface by irradiating image light from the laser exposure device 10 after being uniformly charged. Around the photoreceptor drum 21, a charging roller 23 for transferring charges to the photoreceptor layer of the photoreceptor drum 21 to uniformly charge the photoreceptor layer, carries toner on an outer peripheral surface thereof, and rotates to expose the toner. Developing roller 2 attached to the electrostatic latent image on body drum 21
4. A cleaning brush 25 for cleaning the toner remaining on the outer peripheral surface of the photosensitive drum 21 after the transfer of the toner image is provided.

FIG. 2 is a schematic diagram showing a process cartridge driving device according to an embodiment of the present invention. In the process cartridge driving device 80 , the driving force is transmitted to the main body of the laser printer 1 from the driving motor 81 and the rotating shaft gear 83 fixed to the rotating shaft 82 of the driving motor, and the driving force is transmitted while being reduced. a reduction mechanism 84 for the driving force transmission gear (driving force transmitting member) 85 is supported to the decelerated driving force is transmitted. The driving force transmission gear 85 has a process car
The transmitted gear 89 (the transmitted portion
Material) is engaged with the transmission gear 89,
Body driving gear 86 and developing roller driving gear 87 (branch
) Are engaged.

As the drive motor 81 , a servo motor, a stepping motor, or the like, which is controlled to keep the number of rotations constant, is used. The speed reduction mechanism 84 is constituted by a plurality of gears. The rotation speed is reduced by the ratio of gears meshed with each other, and the photosensitive drum 21 and the developing roller 24 are driven to rotate at a predetermined speed. I have.

In the above-described laser printer, when a digital image signal is input from an external device, the photosensitive drum 21 and the charging roller 23 are driven, and the photosensitive drum 2 is driven.
1 is uniformly charged. Then, a blinking laser beam is irradiated based on the image signal, and an electrostatic latent image is formed on the photosensitive drum 21. This electrostatic latent image is conveyed to a position facing the developing roller 24 by the rotation of the photosensitive drum 21, and the toner is transferred from the developing roller 24 to become a toner image. The toner image is transferred onto the recording paper by the transfer device 40, and is fused to the recording paper by being heated and pressed by the fixing device 50.

While such an image forming operation is being performed, the photosensitive drum 21, the developing roller 24, the charging roller 2
3. The cleaning brush 25, the developer stirring member (not shown), and the like are driven to rotate. These members are driven by a drive motor 81 supported by the main body of the laser printer 1 by a driving device 80 of the process cartridge. Done through

In this process cartridge driving device, the driving force from the driving motor 81 is transmitted to the driving force transmitting gear 85 via the speed reduction mechanism 84 and is input to the transmitted gear 89 supported by the process cartridge 20 . Then, the transmission gear 89 is divided and transmitted from the transmitted gear 89 to the photoconductor driving gear 86 and the developing roll driving gear 87. Therefore, when the process cartridge 20 is attached or detached, only one pair of the driving force transmission gear 85 and the transmitted gear 89 may be connected or disconnected, and the process cartridge can be attached and detached easily and easily. Further, even if a slight rotation unevenness occurs due to the load caused by the rotation driving of the developing roller 24 and the charging roller 23, the influence on the rotation of the photosensitive drum 21 is small, and the rotation of the photosensitive drum at a uniform speed can be achieved. it can.

[0022] The drive device for a process cartridge of this embodiment, a from the drive motor 81 to the photosensitive drum 21, among the path for transmitting the driving force to the developing roller 24 from the drive motor 81, the from the drive motor 81 Transmission gear
By using a common value of 89 , the photosensitive drum 21 can be rotated at a constant speed while suppressing an increase in the gear. Note that the developing roller driving gear 87
A gear for transmitting a driving force to the cleaning brush 25 or the like may be meshed with the driving roller 87 to transmit the driving force further downstream from the developing roller driving gear 87.

Further, the above examples are intended to drive one of a process cartridge provided in all monochromatic image forming apparatus, the invention described in claim 1 or claim 2, respectively, Figure 3 A plurality of process cartridges 320 provided in the color image forming apparatus 301 as shown in FIG.
Can also be applied to the driving device of each process cartridge that drives.

[0024]

As described above, the process cartridge driving apparatus according to the present invention has the branching means in the path for transmitting the driving force from the driving motor to the image carrier, and the drive divided by the branching means. Since the developing device or the cleaning device is driven to rotate by the force, the influence of the rotation unevenness due to the load on the developing device or the cleaning device hardly affects the image carrier, and the image carrier is driven at a constant speed. For this reason, the image formed on the image carrier is good without density unevenness or color tone unevenness. Further, since the driving force from the driving motor is transmitted to the branching means by a single path, it is possible to avoid duplication of members constituting the driving force transmission path to the branching means and to make the driving device a simple structure. it can.

Furthermore, in this process cartridge driving device, the driving force from the driving motor is transmitted into the process cartridge through a single path. Connection and disconnection parts are minimized,
The process cartridge can be easily and easily attached and detached.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a laser printer using a process cartridge driving device according to the first or second aspect of the present invention.

FIG. 2 is a schematic configuration diagram showing a driving device for a process cartridge according to an embodiment of the invention described in claim 1 or 2;

FIG. 3 is a schematic configuration diagram showing another example of an image forming apparatus using the process cartridge driving device according to the first or second aspect of the present invention.

FIG. 4 is a schematic configuration diagram illustrating an example of a conventionally known process cartridge.

FIG. 5 is a block diagram illustrating a transmission path of a driving force from a driving motor in a conventional process cartridge driving device.

FIG. 6 is a diagram illustrating a problem in an image forming apparatus using a conventional process cartridge driving device.

FIG. 7 is a block diagram illustrating a transmission path of a driving force from a driving motor in another example of a conventionally known process cartridge driving device.

[Explanation of symbols]

REFERENCE SIGNS LIST 20 process cartridge 21 photosensitive drum 22 housing 23 charging roller 24 developing roller 25 cleaning brush 80 process cartridge driving device 81 drive motor 82 rotating shaft 83 rotating shaft gear 84 reduction mechanism 85 driving force transmission gear 86 photosensitive member driving gear 87 developing Roller drive gear 89 Transmitted gear

Continuation of front page (56) References JP-A-7-112547 (JP, A) JP-A-7-114322 (JP, A) JP-A-5-80651 (JP, A) JP-A-7-304233 (JP) JP-A-6-148966 (JP, A) JP-A-6-51576 (JP, A) JP-A-2-306256 (JP, A) JP-A-3-117241 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 15/00 550 G03G 21/18

Claims (2)

(57) [Claims] An image carrier of a process cartridge detachably mounted on the image forming apparatus main body and a developing device for visualizing an electrostatic latent image formed on the image carrier; in the driving device of a process cartridge to transmit a driving force from a driving motor provided in, after transmitting the driving force to the image bearing member from said driving motor
A speed reduction mechanism for transmitting the driving force while reducing the driving force to a portion of the road supported by the image forming apparatus main body, and engaging with a portion supported by the process cartridge.
A driving force transmitting member for transmitting a driving force, and a driven member detachably engaged with the driving force transmitting member at a portion supported by the process cartridge.
And the driving force transmitted to the transmitted member is divided into
Branching means for transmitting the driving force to the drive unit of the process cartridge
And a driving device for a process cartridge. 2. The driving device for a process cartridge according to claim 1, wherein the branching unit includes a driving force transmitted to the image carrier and the driving force.
The driving force is divided into the driving force transmitted to the developing device.
A drive unit for a process cartridge,
Place.