JP2000112240A - Developing cartridge, image forming device and driven- side driving force transmission member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the rotational irregularity of a developing roller and to obtain high image quality without enhancing the accuracy of a driving force transmission member as for the driving force transmission member transmitting driving force to the developing roller of a developing cartridge from an image forming device main body side. SOLUTION: The driving force transmission member is the gear train consisting of a stepped driving gear 23a, a developing roller gear 23b, a stepped idler gear 23c, a stirring gear 23d and the like. The gear 23a is constituted of a coupling part 23a3 to which the driving force is transmitted from the device main body and a large gear 23a1 and a small gear 23a2 branching the driving force and transmitting it to the gear train. Besides, the gear 23a is freely rotatably fitted to the end part of a cartridge frame. The gear 23b is fitted to the rotary shaft 12c of the developing roller so that it is not rotated. Then, polyacetal is used for the driving-side gear 23a and polyamide or aliphatic polyketone whose modulus of bending elasticity is lower than that of polyacetal and which absorbs vibration more than polyacetal is used for the driven-side gear 23b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing cartridge and an image forming apparatus having the same, and more particularly to a driving force transmitting member for a developing roller.

[0002] In the present invention, an image forming apparatus refers to an apparatus which forms an image on a recording medium by using an electrophotographic image forming process, such as an electrophotographic copying machine, an electrophotographic printer (for example, a laser beam printer, an LED printer, etc. ), A facsimile machine and a word processor. The developing cartridge is one in which the developing means is integrally formed as a cartridge, and this cartridge is made detachable from the main body of the image forming apparatus.

[0003]

2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic process, a process in which an electrophotographic photosensitive member and a process means acting on the electrophotographic photosensitive member are integrally formed into a cartridge and the cartridge is detachably mountable to the image forming apparatus main body. A cartridge system is known.

According to this process cartridge system,
Since the maintenance of the device can be performed by the user himself without relying on a service person, the operability can be remarkably improved. Therefore, this process cartridge system is widely used in image forming apparatuses.

When the life of the electrophotographic photosensitive member is prolonged and the number of printable sheets is increased, a developing unit for developing a latent image on the electrophotographic photosensitive member is provided as an independent unit using developing means having a limited supply capacity of a developer. And a toner cartridge containing toner, and a developing cartridge integrated with an electrophotographic photoreceptor, a charging unit and a cleaning unit. In addition, they are being used in accordance with the life of each main component.

The developing cartridge drives a developing roller, a toner application roller, a toner stirring means, and the like by a driving force transmitted from the image forming apparatus main body, and the driving force is transmitted by a driving force transmitting member such as a gear train. Is done.

[0007]

As described above, since the developing means uses the gear mechanism as the driving force transmitting member, if there is vibration of the gear pitch or the like, uneven rotation of the developing roller or the like due to vibration of the gear pitch or the like is caused. Is transmitted to the electrophotographic photosensitive member,
As a result, line unevenness corresponding to the gear pitch occurs in an image output on a recording medium such as paper, and the image quality deteriorates, which is visually recognized as shading.

Conventionally, in order to suppress such unevenness in image density, vibration of the gear pitch and uneven rotation have been suppressed by improving the accuracy of the gear. However, there is a limit to the suppression of vibration and uneven rotation due to the improvement in accuracy, and there is a problem that the manufacturing cost of parts including gears increases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a developing cartridge capable of reducing uneven rotation of a developing roller and providing high image quality without increasing the accuracy of a driving force transmitting member, an image forming apparatus having the same, and a driven apparatus. The object is to provide a side drive force transmitting member.

[0010]

The above object is achieved by a developing cartridge, an image forming apparatus, and a driven-side driving force transmitting member according to the present invention. In summary, at least the present invention is rotatably supported on the developing means support frame,
A developing roller that carries a developer that develops a latent image formed on the electrophotographic photosensitive member; a driven-side driving force transmitting member that is non-rotatably mounted on the developing roller; A driving-side driving force transmitting member for transmitting a driving force for driving the developing roller, wherein the developing cartridge is detachable from the electrophotographic image forming apparatus main body.
A developing cartridge wherein the driven-side driving force transmitting member is formed of a material having a lower bending elastic modulus than the driving-side driving force transmitting member. Further, the present invention is an image forming apparatus in which the developing cartridge is detachable from an image forming apparatus main body.

According to the present invention, each of the driven-side driving force transmitting member and the driving-side driving force transmitting member is a set of gear trains. The material of the driven-side driving force transmitting member is polyamide or aliphatic polyketone, and the material of the driven-side driving force transmitting member is polyacetal.

Further, the present invention provides at least a developing roller rotatably supported by a developing means support frame and carrying a developer for developing a latent image formed on an electrophotographic photosensitive member, and driving the developing roller. A drive-side driving force transmitting member for transmitting a driving force to be applied to the developing roller, and is used for a developing cartridge detachable from the electrophotographic image forming apparatus main body. In the driven-side driving force transmitting member attached to the rotation, the driven-side driving force transmitting member is formed of a material having a lower bending elastic modulus than the driving-side driving force transmitting member. It is a force transmission member. According to the present invention,
The material of the driven-side driving force transmitting member is polyamide or aliphatic polyketone.

[0013]

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

FIG. 1 is an overall configuration diagram showing an embodiment of the image forming apparatus of the present invention. This image forming apparatus is configured as a color laser printer.

First, the overall configuration of the image forming apparatus according to the present embodiment will be described.

[Overall Description of Image Forming Apparatus] As shown in FIG. 1, a color laser printer comprises an electrophotographic photosensitive member (photosensitive drum) 1 rotating at a constant speed, and four rotary developing cartridges D, that is, The image forming section includes a yellow developing cartridge Dy, a magenta developing cartridge Dm, a cyan developing cartridge Dc, and a black developing cartridge Db.

Below the image forming section, an intermediate for holding the multi-transferred color toner image formed in the image forming section and further transferring the color toner image to the transfer material P fed from the sheet feeding section by the conveying means 5. A transfer belt (intermediate transfer member) 4 is provided.

The transfer material P on which the toner image has been transferred from the intermediate transfer belt 4 is conveyed to a fixing unit 7, where the toner image is fixed on the transfer material P, and then discharged to a discharge unit 8 on the upper surface of the apparatus by a discharge roller 5f. .

Next, the configuration of each part of the image forming apparatus will be described in detail.

[Drum Unit] A photosensitive drum 1 and a container 9 of a cleaning device also serving as a holder for the photosensitive drum 1
a is integrally formed with the drum unit U. The drum unit U is detachably supported by the printer main body 30 so that the photosensitive drum 1 can be easily replaced according to the life.

In this embodiment, the photosensitive drum 1 has an organic photoconductor layer applied to the outside of an aluminum cylinder having a diameter of about 50 mm, and is rotatably supported by the container 9a of the cleaning device as described above. Have been. By transmitting the driving force of a drive motor (not shown) to one end of the photosensitive drum 1, the photosensitive drum 1 is rotated counterclockwise in the figure according to the image forming operation.

On the periphery of the photosensitive drum 1, there are disposed a cleaner blade 9b for removing transfer residual toner remaining on the surface of the photosensitive drum 1, and a primary charging means 2 for uniformly charging the surface of the photosensitive drum 1. .

[Primary Charging Means] The primary charging means 2 is a conductive roller using a contact charging method. The conductive roller 2 is brought into contact with the photosensitive drum 1 and a voltage is applied to the conductive roller 2. Thereby, the surface of the photosensitive drum 1 is uniformly charged.

[Exposure Means] Exposure to the photosensitive drum 1 is performed from the scanner unit 3. The image signal is sent to the scanner unit 3
When the laser diode is applied to the polygon mirror 3, the laser diode outputs an image corresponding to the image signal.
Irradiate a.

The polygon mirror 3a is a scanner motor 3
b, the image light reflected by the polygon mirror 3a selectively exposes the surface of the photosensitive drum 1 rotating at a constant speed via the imaging lens 3c and the reflection mirror 3d, and is exposed to the surface of the photosensitive drum 1 An electrostatic latent image is formed.

[Developing Unit] In this embodiment, the photosensitive drum 1
In order to develop the above electrostatic latent image, as a developing means, as described above, four rotary developing cartridges Dy, Dm, Dc, and Db capable of developing each color of yellow, magenta, cyan, and black are used. It has.

These developing cartridges D (Dy to Db)
As shown in FIGS. 1 to 3, each is detachably held by a developing rotary 11 that rotates around a shaft 10.

At the time of image formation, each developing cartridge D is rotated around the shaft 10 while being held by the developing rotary 11, and a predetermined developing cartridge is stopped at a position facing the photosensitive drum 1, and further described later. The developing roller is positioned so as to face the photosensitive drum 1 with a small gap (about 300 μm).
Used for developing the latent image.

When forming a color image, the intermediate transfer belt 4
The rotation of the developing rotary unit 11 is performed for each rotation of the developing device, and the developing is performed in the order of the yellow developing cartridge Dy, the magenta developing cartridge Dm, the cyan developing cartridge Dc, and the black developing cartridge Db.

In FIG. 4, the yellow developing cartridge Dy
Is positioned at a position facing the photosensitive drum 1 and is stationary. The developing cartridge Dy feeds the yellow toner in the toner container 63a with the toner feeding mechanism 1
5, the toner is thinned on the outer peripheral surface of the developing roller 12 which rotates clockwise in the figure by the applying roller 19 which rotates clockwise in the figure and the blade 16 which is pressed against the outer periphery of the developing roller 12. Layer applied,
In addition, a triboelectric charge is applied to the toner.

Then, by applying a developing bias to the developing roller 12 facing the photosensitive drum 1, the latent image on the photosensitive drum 1 is developed to form a yellow toner image corresponding to the latent image.

The magenta developing cartridge Dm, cyan developing cartridge Dc, and black developing cartridge Db are also developed by the same mechanism as described above.

Each developing roller 12 of each developing cartridge D
When each developing cartridge is rotationally moved to the developing position, the developing cartridge is connected to a high-voltage power source and a driving source for developing each color provided in the printer main body 30, and a developing voltage is sequentially and selectively applied to each developing cartridge. Drive is transmitted.

The magenta developing cartridge Dm and the cyan developing cartridge Dc have the same configuration as the yellow developing cartridge Dy shown in detail in FIG.
The developing roller 63A of the cartridge frame 63 is provided with a coating roller 19 having a circumferential surface that moves in the opposite direction to the circumferential surface of the developing roller 63A.

The black developing cartridge Db has no coating roller as shown in FIG. The toner of the black developing cartridge Db adheres to the peripheral surface of the developing roller 12 by magnetic force, and the toner layer thickness is regulated by the developing blade 16 which is in contact with the peripheral surface of the developing roller 12, and the triboelectric charge is applied to the toner. You.

[Intermediate Transfer Body] The intermediate transfer belt 4 is a belt device in which an endless dielectric belt is wrapped around a pulley, and the toner on the photosensitive drum 1 visualized by each developing cartridge during a color image forming operation. Since the image is subjected to multiple transfer four times (images of four colors of Y, M, C, and B), the image is rotated clockwise in FIG. In addition, the intermediate transfer belt 4 that has undergone the multiple transfer simultaneously transfers the toner images of the respective colors on the intermediate transfer belt 4 onto the transfer material P by nipping and transferring the transfer material P by the transfer roller 6 to which a voltage is applied. .

[Cleaning means] Cleaning means 9
Is to clean the transfer residual toner remaining on the photosensitive drum 1 after the toner image developed on the photosensitive drum 1 by the developing means is transferred to the intermediate transfer belt 4. The removed removed toner T 'is stored in the cleaner container 9c.

This container 9c can hold the removed toner T 'for the life of the photosensitive drum 1 or more, and therefore, the cleaner container 9c
Is replaced as a unit when the photosensitive drum 1 reaches the end of its life.

[Sheet Feeding Unit] The sheet feeding unit feeds the transfer material P to the image forming unit by the conveying unit 5.
Is mainly composed of a paper feed cassette 5a containing a plurality of transfer materials P, a paper feed roller 5b, a feed roller 5c1, a retard roller 5c2 for preventing double feed, a paper feed guide 5g, and a registration roller 5e.

During image formation, the paper feed roller 5b is driven and rotated in accordance with the image forming operation, and the transfer material P in the cassette 5a is rotated.
Are separated and fed one by one, guided by a paper feed guide 5g, and reach a registration roller 5e via a feed roller 5c1.

During the image forming operation, the registration rollers 5e
A non-rotational operation of causing the transfer material P to stand still and a rotation operation of transporting the transfer material P toward the intermediate transfer belt 4 are performed in a predetermined sequence. Align with P.

[Transfer Section] The transfer section includes a transfer roller 6 as a transfer member. The transfer roller 6 is formed by winding a medium-resistance foam elastic body around a metal shaft, and can swing up and down and rotate in the figure.

While forming the four-color toner image on the intermediate transfer belt 4, that is, while the intermediate transfer belt 4 is rotated a plurality of times, the transfer roller 6 is indicated by a solid line in FIG. And is separated from the intermediate transfer belt 4.

After the formation of the four color toner images on the intermediate transfer belt 4, the transfer roller 6 is indicated by a dotted line in the figure by a cam member (not shown) in accordance with the timing of transferring the toner image to the transfer material P. In the upper position, the transfer material P
Is pressed against the intermediate transfer belt 4 with a predetermined pressure.
At this time, a bias is applied to the transfer roller 6 at the same time, and the toner image on the intermediate transfer belt 4 is transferred to the transfer material P.

Here, the intermediate transfer belt 4 and the transfer roller 6
Means that the transfer material P is sandwiched between the two, and at the same time as the transfer process is performed, the transfer material P is conveyed at a predetermined speed to the left in FIG.
Sent to

[Fixing Unit] The fixing unit 7 fixes the toner image transferred onto the transfer material P. As shown in FIG. 1, as shown in FIG.
b. The fixing roller 7a and the pressure roller 7b are formed as hollow rollers, and each has a heater inside.

The fixing roller 7a and the pressure roller 7b are driven to rotate to heat and press the transfer material P sandwiched therebetween to fix the toner image and to convey the transfer material P.

[Attaching the Developing Cartridge to the Image Forming Apparatus Main Body] First, by pressing a button (not shown) of the printer main body 30, the rotary unit 11 is moved to a predetermined position where the developing cartridge D of a desired color can be installed.
Rotates around the shaft 10 and stops.

Next, the cover 17 of the developing cartridge insertion slot 18 provided in a part of the printer main body 30 is opened.
Normally, the insertion port 18 is closed by the cover 17.

As shown in FIG. 2, the guide rib 70 provided on the side surface of the shutter 64 (details will be described later) of the developing cartridge D is aligned with the cartridge guide 59f on the inner wall of the rotary unit 11 of the printer main body 30, and the developing is performed. Push and insert the cartridge D. Then, the shutter 64 is fixed to the rotary unit 11 by pressing the concave portion 63f (see FIG. 7) provided integrally with the cartridge frame 63A of the developing cartridge D in the direction of arrow A in FIG. Only the developing unit d rotates, and the developing roller 12 appears to be ready for development (see FIG. 5).

[Shutter] The shutter 64 of the developing cartridge D will be described with reference to FIGS.

As shown in FIG. 8, the shutter 64 of the developing cartridge D has side walls 64e at both longitudinal ends thereof.
A round hole 64a is provided in 64f, and the shutter 64 is rotatably attached to the cartridge frame 63 by fitting the round hole 64a into the protruding portions 63c and 63g.

As shown in FIGS. 6 and 7, the shutter 64 is movable between a cover position where the developing roller 12 is covered and a retracted position where the shutter 64 is exposed. In a state where the developing cartridge D is removed from the main body 30, it is in a closed state. Therefore, when the developing cartridge D is in an unused state, dust and the like do not adhere to the developing roller 12 and the developing roller 12 is not damaged.

As shown in FIG. 8, a lock member 71 for locking the shutter 64 in a closed state is provided near the protrusion 63c of the cartridge frame 63. The lock member 71 is provided with an arm portion 71 having elasticity.
a and the engaging portion 71b are formed. On the other hand, shutter 6
At a predetermined position of the side wall 64e, an engagement recess 64t serving as an engagement portion is provided. Thus, when the shutter 64 is in the closed state, the engaging portion 71b is engaged with the engaging concave portion 64t, so that the shutter 64 is locked in the closed state and will not be opened carelessly. I have.

The side wall 64e of the shutter 64 is provided with a round hole 64u, and the developing unit side wall 63h is also provided with a hemispherical projection 63d at a corresponding position.
Therefore, when the shutter 64 is closed, the round hole 64
Since u is fitted to the hemispherical projection 63d, even if the shutter 64 is unlocked as described above, the developing cartridge D does not rotate to an unstable position with respect to the shutter 64. .

[Developing Cartridge Driving Force Transmitting Means] The driving force transmitting means of the developing cartridge D is shown in FIGS.
This will be described with reference to FIG.

FIG. 9 shows color developing cartridges Dy, Dm,
Dc shows a driving force transmission device. The driving force transmission device is a gear train including a stepped driving gear 23a, a developing roller gear 23b, a stepped idler gear 23c, a stirring gear 23d, and an application roller gear 23e. On the other hand, since the black developing cartridge Db does not have the application roller 19, it does not have the application roller gear 23e.

The stepped gear 23a includes a coupling portion 23a3 to which the drive from the image forming apparatus main body is transmitted, a large gear 23a1, and a small gear 2 to branch and transmit the driving force to the gear train.
3a2, the projecting shaft 6 of the coupling frame 63F at the end of the cartridge frame 63A shown in FIG.
It is rotatably attached to 3Fb. The developing roller driving gear 23b is non-rotatably fitted on the rotating shaft 12c of the developing roller having a two-way shape.

The driving force of the developing cartridge is transmitted from a coupling (not shown) provided in the main body of the image forming apparatus to the coupling 23a3 of the stepped gear 23a. The driving force transmitted to the stepped gear 23a is branched from the large gear 23a1 to the developing roller gear 23b, transmitted from the small gear 23a2 via the application roller gear 23e and the stepped idler gear 23c to the stirring gear 23d, and transmitted. The application roller 19 and the toner feed mechanism 15 are driven.

The present invention is characterized in that polyacetal is used as the material of the stepped drive gear 23a on the driving side, and polyamide or aliphatic polyketone is used as the material of the developing roller gear 23b on the driven side.

As shown in FIG. 11, the bending elastic moduli of polyacetal, polyamide and aliphatic polyketone are 1.6 to 3.0 in the normal temperature range of 20 ° C. to 80 ° C., respectively.
GP, 0.4-1.3 GPa and 0.7-1.6 GP
a. That is, since the polyamide and the aliphatic polyketone have a lower flexural modulus than the polyacetal, the logarithmic decay rate is large, and therefore, the developing roller gear 23b made of the polyamide and the aliphatic ketone absorbs a large amount of vibration.

Accordingly, the driving force from the stepped driving gear 23a is applied to the developing roller gear 23b, and these gears 23a, 23
The vibration can be transmitted without depending on the precision of b. As a result, the uneven rotation of the developing roller 12 is reduced, and the uneven density corresponding to the gear pitch is generated in the image on the transfer material P. Can be prevented.

[0063]

As described above, according to the present invention,
For a driving force transmitting member for transmitting a driving force from the apparatus main body to a developing roller of a developing cartridge detachably installed in the image forming apparatus main body, a developing roller gear of a driven side member non-rotatably attached to the developing roller. As a material of the developing roller, a material having a lower bending elastic modulus than the stepped driving gear of the driving side member that transmits the driving force by contacting the developing roller gear is used. As a result, it is possible to prevent the occurrence of density unevenness due to uneven rotation of the developing roller in the image on the transfer material.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing a main part of an embodiment of an image forming apparatus of the present invention.

FIG. 2 is a front view showing a rotary unit installed in the image forming apparatus of FIG. 1;

FIG. 3 is a front view showing a state where a developing roller is mounted on the rotary unit of FIG. 2;

FIG. 4 is a main longitudinal sectional view showing a color developing cartridge installed in the image forming apparatus of FIG. 1;

FIG. 5 is a main vertical sectional view showing a black developing cartridge installed in the image forming apparatus of FIG. 1;

6 is a perspective view of the developing cartridge shown in FIGS. 4 and 5. FIG.

FIG. 7 is a perspective view showing the developing cartridge of FIG. 6 in an inverted manner.

FIG. 8 is an exploded perspective view of the developing cartridge of FIG.

FIG. 9 is a cross-sectional view showing a right end portion of the developing cartridge of FIG. 6 exposed.

10 is a perspective view showing a right side portion of the developing cartridge shown in FIG. 6 in an exposed manner.

FIG. 11 is a graph showing the temperature characteristics of the flexural modulus of the polyacetal used for the stepped drive gear on the developing roller driving side of the developing cartridge and the polyamide and aliphatic polyketone used for the developing roller gear on the developing roller driven side in the present invention. is there.

[Explanation of symbols]

 Reference Signs List 1 photosensitive drum 11 rotary unit 12 developing roller 17 developing cartridge insertion opening 23a stepped drive gear 23a1 large gear 23a2 small gear 23a3 coupling part 23b developing roller gear D, Dy to Db developing cartridge

Claims (6)

[Claims] At least a developing roller for supporting a developer for developing a latent image formed on an electrophotographic photosensitive member rotatably supported by a developing means support frame, and a non-rotatably attached to the developing roller. A driven-side driving force transmitting member, and a driving-side driving force transmitting member that contacts the driven-side driving force transmitting member and transmits a driving force for driving the developing roller. In the detachable developing cartridge, the driven-side driving force transmitting member may include:
A developing cartridge formed of a material having a lower bending elastic modulus than the driving-side driving force transmitting member. 2. The developing cartridge according to claim 1, wherein each of the driven-side driving force transmitting member and the driving-side driving force transmitting member is a set of gear trains. 3. The developing cartridge according to claim 1, wherein a material of the driven-side driving force transmitting member is polyamide or aliphatic polyketone, and a material of the driven-side driving force transmitting member is polyacetal. 4. An image forming apparatus in which the developing cartridge according to claim 1 is detachable. 5. A developing roller, which is rotatably supported by a developing means support frame and carries a developer for developing a latent image formed on the electrophotographic photosensitive member, and a driving force for driving the developing roller. A driving-side driving force transmitting member for transmitting the driving-side driving force transmitting member, the developing-side driving force transmitting member being used for a developing cartridge detachably mountable to the main body of the electrophotographic image forming apparatus; In the driven-side driving force transmitting member, the driven-side driving force transmitting member is formed of a material having a lower bending elastic modulus than the driving-side driving force transmitting member. 6. The driven-side driving force transmitting member according to claim 5, wherein a material of the driven-side driving force transmitting member is polyamide or aliphatic polyketone.