JPH10104903A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an image with a constant density without uneven distribution of dots, and eliminate unevenness in color by providing driving means for rotating an electrostatic latent image carrier comprising a power source and a pair of gears, and setting the rotating quantity of the electrostatic latent image carrier per tooth of the gears to a specified range. SOLUTION: A rotating quantity of an electrostatic latent image carrier per teeth of a pair of gears is set to 1/(150×N1) inch or 1/(180×N2) inch (N1 and N2 are integers of 1 or more). Namely, the number of teeth of a gear 43 integrated with a roller 2 is set to 300 so that the rotating quantity of a belt 1 per tooth of the gear is 1/150 inch, while the rotating quantity of the belt 1 every rotation of the roller is 2 inches. Although the belt 1 is fluctuated in speed by the transmission fluctuation of gears 13, 43, the fluctuating period of the belt 1 is equal to the pitch between dots since the reduction ratio of the gears 13, 43 is set to a rotating quantity per tooth of 1/150 inch in one period of the speed fluctuation, and no uneven distribution of dots is caused.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus to which electrophotography is applied, such as a copying machine, a printer, and a facsimile.

[0002]

2. Description of the Related Art In recent years, a photosensitive member in an image forming apparatus is generally driven to rotate by a power source such as a motor via a gear. FIG. 1 is a structural diagram of a general color image forming apparatus. 4 and 5 are configuration diagrams of a driving unit of a conventional image forming apparatus. Reference numeral 1 denotes a photosensitive belt as an electrostatic latent image carrier on which a photosensitive receiving layer such as an organic photoconductor (OPC) is applied in a thin film shape. The photoreceptor belt 1 is tuned and supported by three rollers of a photoreceptor belt drive roller 2 and photoreceptor belt support / conveyance rollers 3 and 4. The photoreceptor belt drive roller 2 has a coaxial gear 5
6 is formed.

Reference numeral 7 denotes an intermediate transfer member belt made of a conductive resin or the like. The intermediate transfer member belt 7 includes an intermediate transfer member belt driving roller 8 and an intermediate transfer member belt supporting / conveying roller 9.
It is supported by tuning. A gear 11 is integrally formed with the intermediate transfer belt driving roller 8. In FIG. 4, reference numeral 12 denotes a drive motor for driving the photosensitive belt and the intermediate transfer belt, and a small gear 13 is integrally formed on the output shaft. The small gear 13 is a gear 5 and a gear 6
Is configured to transmit the rotation of the drive motor 12 meshing with the gear 11. The photoreceptor belt 1 is rotated by a drive motor 12 in the direction of arrow A along the photoreceptor belt drive roller 2 and the photoreceptor belt support / conveyance rollers 3 and 4 (FIG. 1). Further, the intermediate transfer belt 7 is rotated by a drive motor 12 in the direction of arrow B along the intermediate transfer belt drive roller 8 and the intermediate transfer belt support and transport rollers 9 and 10.

[0004] Developing devices 14B, 14 for storing developers of respective colors of black (B), yellow (Y), magenta (M), and cyan (C) along the outer peripheral surface of the photoreceptor belt 1
Y, 14M, and 14C are provided. Photoreceptor belt 1
In the lower part of the photoconductor cleaning device 15, the static eliminator 16,
A charger 17 is provided, and a laser beam generator 18 is provided above the photoconductor supporting roller 2. The charger 17 includes a charging wire 19 made of a tungsten wire or the like, a shield plate 20 made of a metal plate, and a grid plate 21. When a high voltage is applied to the charging line 19, the charging line 19 causes a corona discharge to uniformly charge the photosensitive belt 1 via the grid plate 21.

[0005] Reference numeral 22 denotes a laser beam of image data emitted from the laser beam generator 18. In the case of a laser printer, the laser beam 22 is controlled by a signal from a host computer (not shown), and a plurality of laser beams corresponding to a specific component among a plurality of predetermined color components are formed on the photoreceptor belt 1. Is formed. The developing units 14B, 14Y, 14M, and 14C of the respective colors are vertically arranged at equal intervals in a predetermined storage portion provided in the body of the apparatus and are detachably arranged in a line in a vertical direction. Is configured. 23B / 23Y / 23M
Reference numeral 23C denotes a contact cam for contacting the developing devices 14B, 14Y, 14M, and 14C with the photoreceptor belt 1 when developing a predetermined color electrostatic latent image.
4Y / 24M / 24C are developing units 14B / 14Y / 14M
A separation spring that separates 14C to the standby position. The contact cams 23B, 23Y, 23M, and 23C are provided on a developing device attaching / detaching cover 25 on a side surface of the apparatus main body. The developing unit detachable cover 25 is supported by a fixed developing unit detachable cover shaft 26 so as to be freely opened and closed. Reference numeral 27, which is disposed to face the photosensitive belt 1 with the intermediate transfer belt 7 interposed therebetween, is an intermediate transfer roller for transferring the toner image on the photosensitive belt 1 onto the intermediate transfer belt 7. Here, the surface circumference of the intermediate transfer belt 7 is set to be equal to the surface circumference of the photoreceptor belt 1.

Reference numeral 28 denotes an intermediate transfer belt cleaning device for scraping off residual toner on the intermediate transfer belt 6, and is separated from the intermediate transfer belt 7 while a synthetic image is formed on the intermediate transfer belt 7. Contact only when it is used for cleaning. Reference numeral 29 denotes a paper cassette that stores the paper 30, and is provided below the intermediate transfer body belt 6. The sheets 30 are sent out one by one from a sheet cassette 29 to a sheet conveying path 33 by a sheet feeding roller 31 and a separation unit 32. Reference numeral 34 denotes a registration roller for temporarily stopping and stopping the sheet 30 in order to match the position of the sheet 26 with the composite image formed on the intermediate transfer belt 6, and is in pressure contact with the driven roller 35. Reference numeral 36 denotes a paper transfer roller for transferring the composite image formed on the intermediate transfer belt 7 to the paper 30, and rotates in contact with the intermediate transfer belt 7 only when the composite image is transferred to the paper 30. Reference numeral 37 denotes a fixing device including a heat roller 38 having a heat source therein and a pressure roller 39. 30 to form a color image.
Reference numerals 40 and 41 are paper discharge roller pairs provided downstream of the fixing device 36. Reference numeral 42 denotes a paper discharge tray provided on the upper part of the machine, and stores the paper 30.

The operation of the conventional image forming apparatus configured as described above will be described below. In FIG.
First, the drive motor 12 is rotated, and the photosensitive belt 1 is moved in the direction of arrow A and the intermediate transfer belt 7 is moved in the direction of arrow B by the photosensitive belt driving roller 2 and the intermediate transfer belt driving roller 8 connected by the small gear 13 and the like. Is rotated around.
Next, a high voltage is applied to the charging line 19 in the charger 17 connected to the high-voltage power supply to cause corona discharge, thereby uniformly charging the surface of the photoreceptor belt 1 to about -500v to -650v. When a laser beam 22 corresponding to a predetermined color of a plurality of color components, for example, a black (B) image, is radiated on the uniformly charged surface of the photoreceptor belt 1, the irradiation on the photoreceptor belt 1 is performed. The charge disappears in the portion where the electrostatic latent image is formed. On the other hand, in the developing device 14B in which the black developer contributing to the development is stored, the contact cam 23B makes a half turn according to a color selection signal from a host computer (not shown), and thereby comes into contact with the photosensitive belt 1. . In the developing device 14B in which the development is completed, the contact cam 23B further rotates a half turn,
It moves from the contact position with the photosensitive belt 1 to the standby position by the spring force of the separation spring 24B. While the developing device 14B is developing, the other developing devices 14Y, 14M, and 14C are separated from the photoconductor 1.

Next, when, for example, the color of cyan (C) is selected, the developing device 14C is brought into contact with the photosensitive belt 1 to start developing cyan. In the case of a copier or printer using four colors, the developing operation is sequentially repeated four times to superimpose the four color B, C, M, Y toner images on the intermediate transfer belt 7 to form a composite image. The composite image formed in this manner is applied to the paper transfer roller 36 with a high voltage of the opposite polarity to the toner and is collectively transferred onto the paper 30 sent from the paper cassette 29 along the paper transport path 33 by the pressure. Subsequently, the toner is sent to the fixing device 37 where the heat and the heat roller 38
Is fixed by the clamping force of the pressure roller 39 to form a color image. The paper 30 that has passed through the fixing device 37 passes through a pair of paper discharge rollers and is discharged to a paper discharge tray 42.

[0009]

In recent years, the demand for higher image quality of image forming apparatuses has been increasing year by year. This is due to an increase in opportunities for outputting photographic images from a computer due to the spread of CD-ROMs, and the fact that digital copiers configured by combining an image forming apparatus with an image reading apparatus have become popular.

It has been found that density unevenness has occurred in the latent image formed on the photosensitive member by the conventional method. It depends on the following reasons. Normally, a gear has a slight variation in transmission speed due to a shape error or a pitch error of each tooth or a meshing state, and is inevitable.

In the image forming apparatus, the above-described series of operations, that is, driving a series (rotational) motion at a constant speed without speed fluctuation is an important factor for achieving high image quality. Above all, even if a slight speed fluctuation occurs in the photoreceptor belt 1, it directly affects the image quality. If the photosensitive belt 1 fluctuates in speed, when an electrostatic latent image is formed, the distance between the pixels varies, and the density of the image is changed. is important. However, in the above-described conventional configuration, the photoconductor is driven by a plurality of gears, and drive unevenness occurs due to meshing of the gears, and the OPC belt causes speed vibration to form a coarse and dense electrostatic latent image, thereby causing image density unevenness. This has been a major obstacle in pursuing high image quality.

This will be described in more detail. FIG. 6 shows a speed waveform of a photosensitive belt of a conventional image forming apparatus and a diagram of a dot latent image formed on the photosensitive member. The resolution of the image forming apparatus is 15
0 DPI (DOT PAR INCH). The pitch between dots is of course 1/150 inch. The photoreceptor belt 1 every time the photoreceptor belt drive roller 2 rotates once
Is 2 inches and the number of teeth of the gear 5 is 70, the photosensitive belt 1 shows a speed waveform as shown in FIG. 6A due to the fluctuation of the drive transmission speed of the small gear 13 and the gear 5. The speed waveform has a period S2 (S2 is a feed amount of one tooth of the gear, that is, 2/7).
0 inches). FIG. 6B shows the photoreceptor belt 1.
Shows the dots formed by irradiating a laser beam on the dot. Black dots indicate the actually formed dots, and dotted lines indicate the positions where they should be formed. As described above, since the laser beam is irradiated while rotating the photoreceptor belt 1, if the dots are irradiated at a fixed time interval (timing), the rotation amount of the photoreceptor belt 1 fluctuates due to the fluctuation of the rotation speed, and FIG. As shown in ()), the density of the dots occurs, and the density of the image becomes uneven.

An object of the present invention is to solve the above-mentioned conventional problems and to provide an image forming apparatus capable of realizing high image quality.

[0014]

According to a first aspect of the present invention, an electrostatic latent image carrier having an electrostatic latent image formed on its surface is developed by a developing device, and toner is transferred from the electrostatic latent image carrier to a sheet. An image forming apparatus that forms an image by transferring an image, the image forming apparatus having a driving unit that rotationally drives the electrostatic latent image carrier including a power source and at least a pair of gears, wherein at least one pair of the gears The amount of rotation of the electrostatic latent image carrier per tooth of the gear is 1 / (150 × N1) inch or 1 / (180 ×
N2) inches (however, N1 and N2 are integers of 1 or more)
And

According to a second aspect of the present invention, a developing device develops an electrostatic latent image carrier having an electrostatic latent image formed on a surface thereof, and a toner image is transferred from the electrostatic latent image carrier to a sheet. An image forming apparatus for forming an image, comprising: driving means for rotationally driving the electrostatic latent image carrier including a power source; a gear integrally provided on an output shaft of the power source; The amount of rotation of the electrostatic latent image carrier per tooth is 1 / (150 × N1)
Inch or 1 / (180 × N2) inch (N1
And N2 is an integer of 1 or more).

According to a third aspect of the present invention, there is provided an electrostatic latent image carrier for holding an electrostatic latent image, an exposure unit for performing line scanning on the electrostatic latent image carrier to perform exposure to form a latent image, An image forming apparatus having a developing device for developing toner on the electrostatic latent image carrier, and forming an image by transferring a toner image from the electrostatic latent image carrier to a sheet, wherein at least one pair of a power source and A driving unit for driving the electrostatic latent image carrier including the gears, wherein the rotation amount of the electrostatic latent image carrier per tooth of at least a pair of gears among the gears is determined by an electrostatic latent image carrier. The pitch was set to be the same as one line pitch of scanning by the exposure means on the outer periphery of the body.

According to a fourth aspect of the present invention, there is provided an electrostatic latent image carrier for holding an electrostatic latent image, an exposure unit for performing line scanning on the electrostatic latent image carrier to perform exposure to form a latent image, An image forming apparatus having a developing device for developing a toner on the electrostatic latent image carrier, and forming an image by transferring a toner image from the electrostatic latent image carrier to a sheet, including a power source. A gear is integrally provided on the output shaft of the power source of the driving means for rotating and driving the electrostatic latent image carrier, and the amount of rotation of the electrostatic latent image carrier per tooth of the gear is determined by the electrostatic latent image carrier. The pitch was set to be the same as one line pitch of scanning by the exposure means on the outer periphery of the body.

According to a fifth aspect of the present invention, the electrostatic latent image carrier is sequentially superimposed and developed by a plurality of different color developing units, and a multi-color toner composite image is formed on the sheet from the electrostatic latent image carrier. A color image forming apparatus for obtaining a multi-color or full-color image by transferring is provided.

According to a sixth aspect of the present invention, the electrostatic latent image carrier is successively developed by a plurality of developing devices of different colors, the toner image is sequentially superimposed on a transfer body, and toner is synthesized from the transfer body onto paper. A color image forming apparatus for obtaining a multi-color or full-color image by transferring an image.

According to a seventh aspect of the present invention, there are provided a plurality of electrostatic latent image carriers and a plurality of developing devices of different colors, the electrostatic latent image carrier is developed by the developing devices, and a toner image is formed on paper. A color image forming apparatus for obtaining a multi-color or full-color image by superimposing and transferring images.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, an electrostatic latent image carrier is driven by a gear, and its reduction ratio is determined by the amount of advance of the electrostatic latent image carrier by one tooth of the gear. And the same resolution as one line pitch, it is possible to obtain a good image without density unevenness without being affected by speed fluctuation of the electrostatic latent image carrier due to drive unevenness generated by gear driving. .

Hereinafter, embodiments of the present invention will be described. FIG. 1 is a configuration diagram of an image forming apparatus according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a driving unit of the image forming apparatus, and FIG. FIG. 9 is a diagram of a dot latent image formed on the image. Here, a detailed description of the same components as those of the image forming apparatus described in the section of the related art will be omitted. The structure of the image forming apparatus is the same except for the drive unit, and the operation is not different from the conventional example.
The resolution of the image forming apparatus is 150 DPI as in the conventional example.
(DOT PAR INCH), and the pitch between dots is 1/150 inch. Photoreceptor belt drive roller 2
The amount of rotation of the photoreceptor belt 1 per rotation is 2 inches, but the gear 43 (FIG. 2) formed integrally with the photoreceptor belt drive roller 2 is a photoreceptor belt 1 per tooth of the gear.
The number of teeth is 300 so that the rotation of
Is set. As shown in FIG. 3A, the photoreceptor belt 1 according to the present embodiment causes a speed change as in the conventional example due to a change in the drive transmission speed of the small gear 13 and the gear 43. However, unlike the conventional example, one cycle S1 of the speed fluctuation is set to 1
The reduction ratio between the gear 3 and the gear 43 is set such that the rotation amount of the photoconductor per tooth of the gear is 1/150 inch. When the photosensitive belt 1 is irradiated with a laser beam to form dots, the speed fluctuation period S 'of the photosensitive belt 1 and the pitch between dots are both equal to 1/150 inch. As shown in FIG. 3B, dot density does not occur.

[0023]

As described above, according to the present invention, it is possible to record the pitch between dots constantly irrespective of the speed fluctuation of the electrostatic latent image carrier, and to form an image at a constant density without density of dots. High image quality without color unevenness can be achieved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a driving unit of the image forming apparatus according to the embodiment of the present invention;

FIG. 3 is a diagram showing a speed waveform of a photoreceptor belt and a dot latent image formed on the photoreceptor of the image forming apparatus according to the embodiment of the present invention;

FIG. 4 is a configuration diagram of a driving unit of a conventional image forming apparatus.

FIG. 5 is a configuration diagram of a driving unit of a conventional image forming apparatus.

FIG. 6 is a diagram showing a velocity waveform of a photoreceptor belt and a dot latent image formed on a photoreceptor of a conventional image forming apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoreceptor belt 2 photoreceptor belt drive roller 3.4 photoreceptor belt support / conveyance roller 7 intermediate transfer member belt 8 intermediate transfer member belt drive roller 9/10 intermediate transfer member belt support / conveyance roller 12 drive motor 13 small gear 16 static eliminator 17 Charger 18 Laser beam generator 30 Paper 37 Fixer

Claims (7)

[Claims] An image forming an image by developing the electrostatic latent image carrier having an electrostatic latent image formed on its surface with a developing device and transferring a toner image from the electrostatic latent image carrier to a sheet. A forming apparatus, comprising: a driving unit that rotationally drives the electrostatic latent image carrier including a power source and at least a pair of gears, wherein the electrostatic latent image carrier per tooth of at least a pair of the gears among the gears is provided. The amount of body rotation is 1 / (150 × N1) inch or 1 / (180 × N2) inch (where N1 and N2
Is an integer of 1 or more). 2. An image forming an image by developing with a developing device on an electrostatic latent image carrier having an electrostatic latent image formed on its surface, and transferring a toner image from the electrostatic latent image carrier to a sheet. A driving device for rotating the electrostatic latent image carrier including a power source, wherein a gear is integrally provided on an output shaft of the power source, and an electrostatic force per tooth of the gear is provided. The rotation amount of the latent image carrier is set to 1 / (150 × N1) inch or 1 / (150 × N1) inch.
(180 × N2) inches (where N1 and N2 are integers of 1 or more). 3. An electrostatic latent image carrier for holding an electrostatic latent image, an exposure unit for performing line scanning on the electrostatic latent image carrier to perform exposure to form a latent image, and the electrostatic latent image. An image forming apparatus having a developing device for developing toner on a carrier, and forming an image by transferring a toner image from an electrostatic latent image carrier to a sheet, comprising: a power source and at least one pair of gears. Driving means for driving the electrostatic latent image carrier to rotate, wherein the amount of rotation of the electrostatic latent image carrier per tooth of at least one of the pair of gears is set to the outer periphery of the electrostatic latent image carrier, An image forming apparatus, wherein the pitch is equal to one line pitch of scanning by an exposure unit. 4. An electrostatic latent image carrier for holding an electrostatic latent image, an exposure unit for performing line scanning on the electrostatic latent image carrier to perform exposure to form a latent image, and the electrostatic latent image. An image forming apparatus having a developing device for developing toner on a carrier, and forming an image by transferring a toner image from the electrostatic latent image carrier to a sheet, wherein the electrostatic latent image carrier including a power source is provided. A gear is integrally provided on the output shaft of the power source of the driving means for rotating and driving the body, and the rotation amount of the electrostatic latent image carrier per tooth of the gear is set to the outer periphery of the electrostatic latent image carrier. An image forming apparatus, wherein the pitch is equal to one line pitch of scanning by an exposure unit. 5. A multi-color toner image is developed by superimposing the electrostatic latent image carrier on a plurality of different color developing devices sequentially, and transferring a multi-color toner composite image from the electrostatic latent image carrier to a sheet. The image forming apparatus according to claim 1, wherein the image forming apparatus is a color image forming apparatus that obtains a color or full-color image. 6. A method for developing a latent image on an electrostatic latent image carrier sequentially with a plurality of developing devices of different colors, superimposing the toner image on a transfer body, and transferring a toner composite image from the transfer body to a sheet. 5. A color image forming apparatus which obtains a multi-color or full-color image by using a color image forming apparatus.
The image forming apparatus according to any one of the above. 7. A developing device having a plurality of electrostatic latent image carriers and a plurality of developing devices of different colors, developing the electrostatic latent image carriers with the developing devices, and transferring the toner image by superimposing the toner image on paper. 5. The image forming apparatus according to claim 1, wherein the image forming apparatus is a color image forming apparatus that obtains a multi-color or full-color image.