JP2006243022A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that can surely prevent a phase shift between gears of a developing roller and a photoreceptor during engagement and can easily adjust the parallelism between the developing roller and photoreceptor with simple constitution. <P>SOLUTION: In the image forming apparatus so configured that a developing cartridge is moved toward a photoreceptor to bring a developer carrier into contact with the photoreceptor for development, and then the developer carrier leaves the photoreceptor when image formation is not performed, an abutting portion is provided to a portion of a guide member guiding a positioning cap provided coaxially with a couple of driven gears. Driving gears provided at both ends of the developing cartridge engages the driven gears through a stage of correcting the parallelism between the developing cartridge and photoreceptor at the abutting portion right before the driving gears and driven gears engage each other at regular positions when the developing cartridge is loaded in a primary apparatus body. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile machine. More specifically, a developing cartridge including a developing device is detachable from the apparatus main body, and a pair of drive gears are provided on the apparatus main body side. The present invention relates to an image forming apparatus having a pair of driven gears on the developing cartridge side, and capable of contacting and separating the developing cartridge with respect to a photosensitive member by meshing between a driving gear and a driven gear.

2. Description of the Related Art Conventionally, an image forming apparatus is known in which a developing device is made into a cartridge and is detachable from an apparatus main body. In such an image forming apparatus, a pair of drive gears on the apparatus main body side and a pair of driven gears on the developer cartridge side are provided, and the developer cartridge and the photosensitive member can be brought into contact with and separated from each other by meshing these gears. It is common.
In order to smoothly perform such a contact operation of the developing cartridge, a slight backlash is required between the developing cartridge and the apparatus main body. There is a problem that it is swung and phase shift occurs.
Therefore, a technique for matching the tooth surface phases of the driving gear and the driven gear has been proposed as a conventional technique (see, for example, Patent Document 1).
The technique disclosed in Patent Document 1 is intended to prevent a phase shift in mounting and holding a developing cartridge by restricting the width in the longitudinal (thrust) direction of a developing roller as a developer carrying member.
JP 2001-83801 A

However, in the regulation with only the thrust width as in Patent Document 1, for example, the diameter of the flange of the positioning cap is 12 mm, the gap with the guide member is 0.1 mm, and the distance between the positioning caps at both ends of the developing roller is about 350 mm. As a result, a deviation of about 3 mm occurs at both ends of the developing roller.
Therefore, for example, if the gap between the positioning cap and the guide member is reduced, variations in component dimensions (tolerance) cannot be absorbed, and the sliding resistance between the components hinders the movement of the developing cartridge.
Accordingly, the present invention has been made in consideration of the above-described circumstances, and the object thereof is to reliably prevent the gear phase shift between the developing roller and the photosensitive member when the gear is engaged, and to prevent the developing roller and the photosensitive member from being parallel. An object of the present invention is to provide an image forming apparatus capable of easily adjusting the degree by a simple configuration.

In order to solve the above-mentioned problems, the present invention described in claim 1 is provided with a developing cartridge that is detachable from the apparatus main body, and forms an image by the drive tangential force of a pair of driven gears provided at both ends of the developing cartridge. Sometimes the developing cartridge is moved to the photosensitive member side, and development is performed by a developer carrying member rotatably provided in the developing cartridge, and the image forming apparatus is separated from the photosensitive member for non-image formation. An image forming apparatus that obtains parallelism between the developing cartridge and the photosensitive member by matching the tooth surface phases of the pair of driven gears and the pair of drive gears provided in the apparatus main body meshing with the pair of driven gears. And a pair of guide members for guiding a positioning cap provided coaxially with the pair of driven gears. When the mounting body is mounted, the parallelism between the developing cartridge and the photosensitive member is corrected at the abutting portion immediately before the tooth tips of the driving gear and the driven gear mesh at a regular position. The drive gear and the driven gear provided on both sides of the developing cartridge are meshed with each other.
The image forming apparatus according to claim 1, wherein the guide member is provided with a step, and the step is longer than a radius of a positioning cap engaged with the guide member. To do.

  According to the present invention, when the developer cartridge is mounted on the apparatus main body, a driving gear and a driven gear are provided on a part of a guide member that guides a positioning cap provided coaxially with a pair of driven gears. Immediately before the tip of the tooth meshes at a regular position, the abutting portion corrects the parallelism between the developing cartridge and the photosensitive member, and a driven gear provided on both sides in the mounting direction of the developing cartridge; It is possible to provide an image forming apparatus capable of reliably preventing a phase shift at the time of meshing with a drive gear provided in the apparatus main body and obtaining a good image.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an image forming apparatus according to the present embodiment.
The image forming apparatus shown in this embodiment is a color laser printer, and includes a photoconductor portion, a writing portion, a developing portion, an intermediate transfer portion, a paper feeding portion, a paper transfer portion, and a fixing portion.
The photoconductor unit includes a photoconductor belt 1a. Around the photoconductor belt 1a, a charger 1b, four developing cartridges 1c having different toner colors, and a photoconductor cleaning device 1d are arranged. An organic photosensitive layer is formed on the surface of the photoreceptor belt 1a.
First, the photosensitive belt 1a is uniformly charged by applying a high voltage to the charger 1b. Next, color image information, for example, a color image signal from a computer is converted into an optical signal, and black (hereinafter referred to as Bk), cyan (hereinafter referred to as C), magenta (hereinafter referred to as M), yellow (hereinafter referred to as Y). The optical writing by the laser corresponding to the image signal is performed via the polygon mirror 1e, the f / θ lens 1f, and the reflection mirror 1g, and an electrostatic latent image is formed on the photosensitive belt 1a.
The electrostatic latent image is developed by electrostatically adsorbing charged toner for each of Bk, C, M, and Y colors by the developing cartridge 1c having toner charged with the opposite charge. At the contact portion between the intermediate transfer belt 1h and the photoreceptor belt 1a, the toner image is transferred onto the intermediate transfer belt 1h by applying a charge opposite to the toner to the intermediate transfer belt 1h. By performing this operation for each of Bk, C, M, and Y colors, a four-color superimposed image is formed on the intermediate transfer belt 1h, and then these four-color superimposed images are transferred to the transfer paper P that has been sent by the transport roller 1i. Then, the toner is transferred by the paper transfer roller 1j to which a charge opposite to that of the toner is applied.
The transfer paper P is stored in a paper feed cassette P1 and fed by a paper feed roller P2. The transfer paper P onto which the toner image has been transferred is conveyed to the fixing device 1k and melts and fixes the toner image.
In the image forming apparatus 100 of this embodiment shown in FIG. 1, the developing cartridge 1c is attached to and detached from the apparatus main body from the developing cartridge mounting operation surface 100A side.

FIG. 2 is a cross-sectional view of the developing drive unit at the Y portion of the schematic configuration diagram of the image forming apparatus shown in FIG.
As shown in FIG. 2, the developing cartridge 1c maintains a positional relationship with the guide member 2d fixed to the housing 2c on the apparatus main body side by positioning caps 2b provided on both ends of the developing roller 2a. ing. The positioning cap 2b has a flange portion that can freely rotate, and is configured such that when the developer cartridge 1c is moved in the attaching / detaching direction, the flange moves along the end portion of the guide member 2d.
The housing 2c on the apparatus body side is provided with a drive shaft 2e for driving the developing roller 2a and a drive gear 2f and a bearing 2g at both ends, and the force from the motor 2h is turned on / off via the clutch 2i. It is turned off and finally transmitted to the driven gear 2j on the axis of the developing roller 2a. Two drive gears 2f are fixed to the drive shaft 2e in a state in which both gears are in phase. That is, the teeth are fixed in a state where the teeth are the same in both gears.
FIG. 3 is a schematic diagram showing the contact / separation mechanism of the developing cartridge of this embodiment.
The state when the developing cartridge 1c is separated and during development is shown.
Here, the Bk, C, M, and Y developing cartridges are each provided with a stopper provided on the housing 2c on the apparatus main body side during development, as shown in FIG. 3A, by an elastic member such as a separation spring 3a. It is spaced apart from the photoreceptor 1a up to the position 3b.
Next, when a driving force is applied in the rotational direction shown in FIG. 3B, the force acts in the tangential direction by the load torque of the developing roller 2a itself, and the developing cartridge 1c moves in the direction of the arrow in the figure.

FIG. 4 is a plan view for explaining the phase shift of the developing roller when the developing cartridge is mounted. FIG. 5 is a side view for explaining a phase shift between the drive gear and the driven gear on the left and right.
As shown in the figure, for example, when the developing roller 2a attached to the developing cartridge 1c is inserted into the apparatus main body with the L side leading in the figure, as shown in FIGS. The engagement (phase) between the pair of drive gears 2f and the driven gear 2j on the side may be shifted by one tooth. In this case, the developing roller 2a is diagonally opposed to the surface of the photosensitive belt 1a on the L side and the R side. In this example, the developing roller 2a on the R side and the surface of the photosensitive belt 1a are in contact with each other. Sufficient contact cannot be obtained, and the image will be white.
Further, since the meshing between the driving gear 2f and the driven gear 2j is also inclined with respect to the tooth surface, horizontal streak density unevenness (banding, jitter) corresponding to the number of teeth and the number of rotations occurs. The L and R mean left (L) and right (R) as viewed from the developing cartridge operation surface 100A side in FIG.

FIG. 6 is a side view showing meshing of the drive gear and the driven gear according to the present embodiment. In the present embodiment, as shown in FIG. 6A, the abutting portion 3d is positioned at the positioning cap abutting position on a part of the guide member 2d on both sides just before the pair of driving gears 2f and the driven gear 2j mesh. (Alternatively, they are arranged to be equidistant from the photosensitive member surface).
Here, when the developing cartridge 1c and the developing roller 2a are inserted and moved obliquely, the leading side (L side in FIG. 4) positioning cap 2b comes into contact with the abutting portion 3d, and the forward movement is temporarily inhibited. . During this time, the developing cap 2b on the trailing side (R side in FIG. 4) also contacts the abutting portion 3d, and the parallelism of the developing cartridge 1c and the developing roller 2a with the surface of the photoreceptor 1a is corrected.
When the developing cartridge 1c is further pressed in the direction of the photosensitive member, the positioning caps 2b on both sides fall below the abutting portion 3d as shown in FIG. 6B, and the driven gear 2j meshes with the driving gear 2f. The pair of gears is on standby in a state where the phase is surely synchronized.
Furthermore, in order to ensure the parallelism correction, as shown in FIG. 6C, by making the step of the guide member longer than the positioning cap radius, the insertion is surely stopped once, and further in parallel. The degree is adjusted.
As described above, according to the present invention, the degree of parallelism is corrected immediately before the pair of gears mesh with each other, and both gears mesh with each other without causing a phase shift. Thus, the contact / separation operation with respect to the photosensitive member 1a during image formation is smoothly performed.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a development driving unit at a Y part of the schematic configuration diagram of the image forming apparatus illustrated in FIG. 1. FIG. 3 is a schematic diagram illustrating a contact / separation mechanism of the developing cartridge according to the exemplary embodiment. FIG. 7 is a plan view for explaining a phase shift of the developing roller when the developing cartridge is mounted. It is a side view for demonstrating the phase shift in the right and left of the drive gear to which this invention is applied, and a driven gear. It is a side view which shows meshing | engagement with the drive gear and driven gear which concern on this embodiment.

Explanation of symbols

  1a photoconductor belt, 1b charger, 1c developing cartridge, 1d photoconductor cleaning device, 1e polygon mirror, 1f f / θ lens, 1g reflection mirror, 1h intermediate transfer belt, 1i transport roller, 1j paper transfer roller, 1k fixing device 2a developing roller, 2b positioning cap, 2c housing, 2d guide member, 2e drive shaft, 2f drive gear, 2g bearing, 2h motor, 2i clutch, 2j driven gear, 3a separation spring, 3b stopper, 3c drive force, 3d Abutting section, 100 image forming apparatus, 100A cartridge mounting operation surface, Y cross section

Claims (2)

  A developing cartridge detachably attached to the apparatus main body is provided, and the developing cartridge is moved toward the photosensitive member and rotated into the developing cartridge during image formation by a driving tangential force of a pair of driven gears provided at both ends of the developing cartridge. An image forming apparatus that performs development with a developer carrier that is freely provided and is separated from the photoconductor for non-image formation, and is provided in the pair of driven gears and the main body of the apparatus that meshes with the driven gears. In the image forming apparatus in which the parallelism between the developing cartridge and the photosensitive member is obtained by matching the tooth surface phases of the pair of drive gears, a positioning cap provided coaxially with the pair of driven gears is guided. When the developing cartridge is mounted on the apparatus main body, the driving gear and the driven gear Immediately before the tip meshes at the normal position, the drive gear and the driven gear provided on both sides of the developer cartridge mesh with each other by correcting the parallelism between the developer cartridge and the photosensitive member at the abutting portion. An image forming apparatus characterized by being configured as described above.   The image forming apparatus according to claim 1, wherein a step is provided on the guide member, and the step is set to be longer than a radius of a positioning cap that engages with the guide member.

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