JPH08194347A - Driving device for recorder - Google Patents

Abstract

PURPOSE: To reduce the cost of the driving device (especially, photoreceptor driving part) of a recorder and to obtain high accuracy required. CONSTITUTION: This driving device is a driving device for a recorder where a color image is formed by forming every color of image on plural photoreceptors 2 and successively transferring the respective color images on transfer paper by an electrophotographic system. In order to eliminate color slurring caused by the eccentricity of a drum gear 14-1 directly driving the shaft 2-1 of each photoreceptor, the drum gear 14-1 is constituted by plurally combining the same gears so that the eccentricity may be accurately eliminated, and the respective gears 15-1 to 15-3 are combined and assembled so as to cancel the direction of the eccentricity. Since the drum gear 14-1 is constituted by plurally combining the same gears and the respective gears are combined and assembled so as to cancel the direction of the eccentricity, the drum gear realizing accurate rotation by combining the inexpensive gears whose accuracy is low instead of the conventional gear whose accuracy is high is produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device for an electrophotographic recording device applied to a color copying machine, a color facsimile, a color printer, a color printing device and the like.

[0002]

2. Description of the Related Art A plurality of photoconductors are provided, and an image for each color is formed on each photoconductor according to image information for each color separation (for example,
Cyan, yellow, magenta, and black toner images), the toner images on each photoconductor are sequentially superimposed and transferred onto the transfer paper, and after transfer, the image is fixed by the electrophotographic recording device that forms a color image on the transfer paper. It is known and applied to color copiers, color facsimiles, color printers, color printers, and the like. In a recording apparatus that forms a color image by using such a plurality of photoconductors, color misregistration may occur due to eccentricity of the photoconductor drive gear, and in order to prevent this color misregistration, gear misalignment may occur. A technique for matching the core phase between adjacent photoconductors has been put into practical use (a color copying machine manufactured by Ricoh Co., Ltd .: Pretail 750, etc.). This is because even if the gear is manufactured with high precision, it must be covered by the phase matching technology.

[0003]

A major cause of image quality deterioration in color images is color misregistration due to uneven rotation of the photoconductor, which is caused by eccentricity of a drum gear that directly drives the photoconductor. Is. For this reason, an ultra-high precision gear without eccentricity is required. However, the ultra-high precision gear is considerably more expensive than general gear production, and cost reduction is a major technical issue.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to achieve a reduction in the cost of a driving device for a recording apparatus and obtain the required high accuracy.

[0005]

In order to achieve the above object, the invention according to claim 1 provides a plurality of photoconductors arranged in parallel, a charging device and an optical writing device arranged around each photoconductor. , A developing device, a transfer device, a cleaning device, a static eliminator, a transfer paper transport device for transporting the transfer paper, a fixing device, and a drive device for driving the photoconductor, and the like. In a driving device of a recording apparatus that forms an image for each color and sequentially transfers each color image on a transfer paper to form a color image, a photoconductor driven gear (hereinafter referred to as a drum gear) that directly drives each photoconductor shaft. In order to eliminate color deviation due to eccentricity, the drum gear is configured by combining a plurality of the same gears to remove the eccentricity with high precision, and each gear is assembled so as to cancel the direction of the eccentricity. Special To.

According to a second aspect of the present invention, in the driving device for the recording apparatus according to the first aspect, when the drum gear is composed of N gears, the direction of eccentricity of each gear is 360 ÷
It is characterized by being rotated by N degrees and assembled.

According to a third aspect of the present invention, in the driving device of the recording apparatus according to the first and second aspects, each drum gear is integrally cut with the base material before gear cutting before manufacturing. It is characterized by being constituted by a plurality of gears having the same eccentricity amount.

According to a fourth aspect of the present invention, in the driving device for the recording apparatus according to the second aspect, a position mark such as a hole or a screw hole penetrating a part of each gear so that each drum gear can be easily assembled. Is characterized in that it is configured (processed).

[0009]

In the drive unit of the present invention, in order to eliminate color deviation due to eccentricity of the drum gears that directly drive the respective photoconductor shafts, the drum gear is formed by combining a plurality of the same gears in order to remove the eccentricity with high accuracy. And, because each gear is assembled so as to cancel the direction of eccentricity,
Instead of the conventional high-precision single gear, it is possible to manufacture a drum gear capable of high-precision rotation by combining low-precision gears that are less accurate.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the illustrated embodiments. FIG. 1 shows a structural example of a color printer for carrying out the present invention. This printer is a color printer using electrophotographic technology, and is provided with four photoconductors 2 arranged in parallel, and a charging device that uniformly applies a charge to the photoconductors 2 around each photoconductor 2 ( In this embodiment, the charging roller method) 3
An optical writing device (LED array in this embodiment) 4 for writing writing data on the uniformly charged photoconductor, and an electric image (electrostatic latent image) formed on the photoconductor for each color. A dry developing device 5 that visualizes with toner, and a transfer device (transfer roller in this embodiment) that transfers the toner image formed on the photoconductor onto a transfer paper.
6, a cleaning device (a blade cleaning method in this embodiment) 7 for cleaning the toner remaining on the photoconductor after the transfer, and a static eliminator (in this embodiment, a charge removal device for removing the electric charge remaining on the photoconductor after the cleaning). An LED light static eliminator) 8 is provided. That is, in the color printer having the configuration shown in FIG. 1, four color image forming devices arranged side by side form, for example, each color image of black toner, magenta toner, yellow toner, and cyan toner on each photoconductor. ing. Further, in the color printer, there is a sheet feeding device 1 for storing transfer paper (1-1 indicates a manual feed table), and the transfer paper is conveyed from right to left in FIG. Conveyance belt 10 for passing each color image on each photoconductor onto a transfer sheet, passing between devices 6, drive roller 10-1 for rotating conveyance belt 10, and timing of image formation process. The registration roller 10-2 that feeds the transfer paper to the conveyor belt, the fixing device 9 that fixes the toner image transferred onto the transfer paper, the electric power supply device 12 of the printer engine, and the above-mentioned devices of the printer are controlled. The control device 13 and the like are arranged.

The color printer shown in FIG.
An image forming apparatus for recording images of respective colors of black toner, magenta toner, yellow toner, and cyan toner is arranged in order from the right to the left in the figure, and when the recording operation is started, the image is formed on each photoconductor 2. Is charged by the charging device 3, and the optical writing device 4
A toner image of each color is formed at a predetermined timing through a process of optical writing by the developer and a development of each color toner of the developing device 5, and the toner image is conveyed by the conveying belt 10 between each photoconductor 2 and each transfer device 6 at a predetermined timing. On the transfer paper that came
Toner images of black toner, magenta toner, yellow toner, and cyan toner are sequentially superposed and transferred from the right side of the drawing, and a color image is transferred to a transfer paper. The transfer sheet after the transfer is separated from the conveyor belt 10 by a separation charger or the like, is sent to the fixing device 9, the toner image is fixed by the fixing device 9, and is then discharged to the paper discharge tray.

A full-color image is formed on the transfer paper as described above. In this method, it is known that color unevenness occurs in the color image due to the uneven rotation of each photoconductor 2 when the uneven rotation occurs. ing. Each photoreceptor 2 has a structure shown in FIG.
Drive shaft (photosensitive member shaft) 2-1 of each photosensitive member 2 as shown in FIG.
A photoreceptor driven gear (hereinafter, referred to as a drum gear) 14-1 for directly driving the drum is fixed to its shaft, and each drum gear 14-1 is connected by drive gears 14-4 and 14-6. In the examples of FIGS. 2 and 3, the center drive gear 14-4 is directly connected to the drive motor 14-5 in the center drive system, and the drive gear 14-4 is rotated by the drive motor 14-5. The four drum gears 14-1 rotate together.

Since each of the drum gears 14-1 has a larger diameter than the other gears, the meshing circle of the teeth with respect to the center of rotation has an eccentricity of about 10 to 50 μm within the processing limit. Therefore, the drive motor 14-5 and the drive gears 14-4, 14-6
Even with high accuracy, the photosensitive member 2 will have uneven rotation due to the eccentricity of the drum gear 14-1. The uneven rotation of the photoconductor 2 causes the writing device 4 to optically write image data on the photoconductor.
Image is unevenly formed on the photoconductor. In addition, the image transferred when the transfer paper is conveyed to the transfer position by the conveyor belt 10 also naturally has an uneven image. Similarly, since the same thing occurs with the second, third, and fourth photoconductors, the superposed images of the color images on the transfer paper do not completely overlap with each other, and a shifted color misregistration image is caused.

The present invention is particularly directed to a photosensitive member 2 for preventing color misregistration.
In the present invention, in order to eliminate color misalignment due to eccentricity of the drum gear 14-1 that directly drives each photoconductor shaft 2-1, the drum gear 14-1 removes the eccentricity with high accuracy. Therefore, a plurality of the same gears (gear) are combined, and each gear is assembled so as to cancel the eccentric direction. Hereinafter, it will be described more specifically.

FIG. 4 shows an example of assembling the drum gear according to the present invention. The drum gear 14 is attached to the drive shaft 2-1 of each photoconductor 2.
-1 is fixed, and the drum gear 14-1 includes a plurality of (three in this embodiment) gears 15-1, 1 as shown in FIG.
5-2 and 15-3, and the plurality of gears 15-
It is fixed with three screws A, B and C to a drive boss 15-4 which is assembled by bundling 1, 15-2 and 15-3. The gears 15-1, 15-2, and 15-3 are gears having the same shape, and when the three-piece structure as shown in FIG. 4 is used, the three base materials before gear cutting of each gear are integrally formed during manufacturing. Overlapping and gear cutting are performed at the same time. Then, gears having substantially the same eccentricity can be manufactured. And when assembling three layers as shown in Fig. 4, the relationship between the three gears when they were manufactured
Assemble 360 ° / 3 = 120 °, shifting the eccentricity by 120 °. This can cancel the eccentricity of each gear. In the example of FIG. 4, three gears 15-1 and 15- are provided so that the drum gear 14-1 can be easily assembled.
When manufacturing 2, 15-3, through holes (or screw holes) which are also used as position marks and which are shifted by 120 ° in three places on each gear.
A, B, C are processed.

Here, FIG. 5 (a) is a diagram showing a state of meshing pitch circles when the three gears are assembled by shifting the eccentric phase by 120 °, and FIG. 5 (b) shows the three gears. It is a figure which shows the position variation (namely, width of eccentricity amplitude) of the meshing point with the drive gear from the rotation center of the drum gear at the time of assembling in an eccentricity offset state like (a). Further, FIG. 6A is a diagram showing a meshing pitch circle of a single eccentric gear, and FIG. 6B is a position variation of a meshing point with a drive gear from a rotation center of a single drum gear (that is, It is a figure which shows the width | variety of eccentricity amplitude. As shown in FIG. 5A, if the three gears are assembled by shifting the eccentric directions by 120 °,
As shown in (b), the position variation (width of eccentricity amplitude) of the substantial pitch circle of the meshing circle when meshing with the drive gear is the position variation of the pitch circle in the single gear shown in FIG. The width of the eccentricity amplitude can be reduced to about 1/3 or less, and the width of the eccentricity amplitude can be reduced. Even if the single gear has an eccentricity of 30 μm, it is possible to obtain 1 by combining 3 pieces as described above.
This corresponds to an ultra-high precision gear with an eccentricity amount of 0 μm.

As described above, in the combination gear according to the present invention, since the eccentricity of the gear unit can be canceled by the combination of a plurality of sheets, the total eccentricity can be reduced. This is a good method for reducing unevenness, and it is possible to use a gear that has been machined with reduced precision with high precision. Therefore, it is possible to manufacture gears with reduced accuracy compared to the case of using an ultra-high accuracy single gear, and if the accuracy when manufacturing gears is reduced, the processing cost can naturally be reduced, so a highly accurate and inexpensive drive device is provided. can do.

[0018]

As described above, in the drive unit of the present invention, color misregistration due to eccentricity of the drum gear that directly drives each photoconductor shaft is eliminated, so that the drum gear is the same in order to remove the eccentricity with high accuracy. It is composed by combining multiple gears, and each gear is assembled so as to cancel the direction of eccentricity, so instead of the conventional high precision single gear By combining them, it is possible to manufacture a drum gear that can rotate with high precision. Therefore, according to the present invention, it is possible to provide an inexpensive drive device equipped with a drum gear that enables highly accurate rotation, and it is possible to realize a low-cost color recording device that is free from color misregistration.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration example of a color printer embodying the present invention.

FIG. 2 is a diagram showing a configuration example of a gear unit of a photoconductor driving device of the color printer having the configuration shown in FIG.

FIG. 3 is a diagram of a photoconductor of the color printer having the configuration shown in FIG. 1 and a gear unit of a drive unit thereof when viewed from above.

FIG. 4 is an explanatory diagram of a drum gear used in the drive device according to the present invention, in which (a) is a sectional view of the drum gear;
(B) is a perspective view schematically showing a state before the assembly of the drum gear.

FIG. 5 is an explanatory view of the eccentricity of the drum gear according to the present invention, FIG. 5A is a view showing a state of meshing pitch circles when the eccentricity phases of three gears are shifted by 120 ° and assembled;
FIG. 6B is a diagram showing a positional variation (width of eccentricity amplitude) of the meshing point with the drive gear from the rotation center of the drum gear when the three gears are assembled in the eccentricity canceling state as shown in FIG. Is.

6A and 6B are explanatory views of eccentricity of a conventional single drum gear, in which FIG. 6A shows a meshing pitch circle of a single gear with eccentricity, and FIG. FIG. 6 is a diagram showing a positional variation (width of eccentricity amplitude) of a meshing point with the drive gear of FIG.

[Explanation of symbols]

1: Paper feeding device 2: Photoconductor 2-1: Drive shaft of photoconductor (photoconductor shaft) 3: Charging device 4: Optical writing device 5: Developing device 6: Transfer device 7: Cleaning device 8: Static eliminator 9 : Fixing device 10: Conveying belt 10-1: Driving roller 10-2: Registration roller 11: Toner replenishing part 12: Power supply device 13: Control device 14-1: Drum gear (photosensitive drum driven gear) 14-4, 14- 6: Drive gear 14-5: Drive motor 15-1, 15-2, 15-3: Gear constituting the drum gear 15-4: Drive boss

Claims (4)

[Claims] 1. A plurality of photoconductors arranged in parallel, a charging device, an optical writing device, a developing device, a transfer device, a cleaning device, a charge eliminating device, which are arranged around each of the photoconductors, and transfer paper. A transfer paper transport device, a fixing device, and a drive device that drives the photoconductor, and forms an image for each color on each photoconductor by an electrophotographic method, and sequentially transfers each color image on the transfer paper. In a driving device of a recording device that forms a color image, the drum gear is highly accurately eccentric because it eliminates color misalignment due to eccentricity of a photoconductor driven gear (hereinafter referred to as a drum gear) that directly drives each photoconductor shaft. A drive device for a recording apparatus, characterized in that a plurality of the same gears are combined in order to remove the above, and each gear is assembled so as to cancel the direction of eccentricity. 2. The recording apparatus drive according to claim 1, wherein when the drum gear is composed of N gears, the gears are assembled by rotating the respective eccentric directions by 360 / N degrees. apparatus. 3. Each of the drum gears is composed of a plurality of gears having the same eccentricity amount, which are obtained by integrally cutting the base materials before gear cutting of the respective gears during production and gear cutting. The driving device for the recording apparatus according to claim 1. 4. A drive device for a recording apparatus according to claim 2, wherein a position mark such as a hole or a screw hole penetrating a part of each gear is formed (working) so that each drum gear can be easily assembled. A drive device for a recording apparatus characterized by the above.