JP3451513B2 - Color image forming equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a plurality of charging, image exposing and developing means on the peripheral surface of a drum-shaped or belt-shaped image forming body so that the toner is imaged during one rotation of the image forming body. The present invention relates to an electrophotographic color image forming apparatus that is formed by superimposing it on top of one another.

[0002]

2. Description of the Related Art As a method for forming a multicolor image, a monochromatic toner image formed on each photoconductor is intermediately transferred by equipping the photoconductor with the same number of images as necessary, a charger and a developing device. A device that creates a color image by overlaying it on the body (A)
An apparatus (B) for forming a color image by repeating charging, image exposure and development for each color by rotating one photoreceptor a plurality of times, or similarly, charging and image exposure for each color within one rotation of one photoreceptor. An apparatus (C) and the like for forming a color image by sequentially performing development are known.

However, the above-mentioned device (A) has a drawback that the volume of the device is increased because a plurality of photoconductors and intermediate transfer members are required, while the device (B) has a charging means, an image exposing means and a photoconductor. However, there is a restriction that the size of the formed image is limited to the surface area of the photoconductor or less.

On the other hand, the device (C) is excellent in that it has no restriction on the image size and can realize high-speed image formation.

[0005]

However, in the apparatus (C), even if the gear on the driving side for transmitting the driving force of the motor to the image forming body has uneven pitch, variation in the meshing depth, etc., the motor is fixed. Even if it rotates at high speed, the transmission speed changes periodically and the peripheral speed of the image forming body becomes uneven, so that the registration of the superimposed images fluctuates,
There is a problem that the color shift occurs and the image quality is remarkably deteriorated.

As a result of solving and improving this point, the present invention provides
An object of the present invention is to provide a color image forming apparatus capable of recording a high-quality image with high accuracy without causing color misregistration even if the transmission speed by the drive-side gear may periodically change. It was done.

[0007]

The above object is to provide a charging means for performing a plurality of charges on the peripheral surface of an image forming body rotated by driving a gear, an image exposing means for forming a latent image, and A developing means for visualizing the latent image is provided, and charging, image exposure, and development are repeated during one rotation of the image forming body to form toner images in a superimposed manner, and then the toner image is transferred. In a color image forming apparatus that transfers the image to the image forming body at once, the large gear integrally fixed to the image forming body is
The image shape is formed by meshing with a drive gear for driving the large gear.
It is configured to rotate the adult body, and
The number of teeth of the large gear between the plurality of image exposure positions on the surface is
Note that there is an integer multiple of the number of teeth of the drive gear, and each image exposure
The present invention is achieved by a color image forming apparatus, which is characterized in that the number of teeth of the large gear between positions is the same .

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to the description of the embodiments, the structure and function of a color image forming apparatus which is the object of the present invention will be described.

FIG. 1 shows a color image forming apparatus in which image exposing means is arranged so as to face the outer peripheral surface of an image forming body, and image exposure is performed from the outside of the image forming body to a photoreceptor on the peripheral surface. It is shown.

Reference numeral 10 denotes a photosensitive drum which is an image forming body, and
The PC photoconductor is applied on the drum, and is rotated clockwise while being grounded.

Reference numeral 11 denotes a scorotron charger, which is a charging means, which performs a charging action on the above-described organic photosensitive layer of the photosensitive drum 10 by a grid held at a predetermined potential and corona discharge by a discharge wire, and the photosensitive drum. A uniform potential is applied to 10.

Reference numeral 12 denotes an exposure optical system which is an image exposure means composed of light emitting elements such as LEDs, FL, EL, PL arranged in the axial direction of the photoconductor drum 10 and a SELFOC lens, which is a separate image reading. The image signals of the respective colors read by the apparatus are sequentially taken out from the memory and input to the respective exposure optical systems 12 as electric signals. The emission wavelength of the light emitting device used in this example is 600-80.
It is in the range of 0 nm.

The exposure optical system 12 includes an L
It may be composed of a combination of optical shutter members such as CD, LISA, PLZT and an image forming lens such as a SELFOC lens as an equal magnification image forming element.

Reference numerals 13Y, 13M, 13C, and 13K denote developing units which are developing means for containing yellow (Y), magenta (M), cyan (C), and black (K) developers, respectively.
The developing sleeves 130 rotate in the same direction while maintaining a predetermined gap with respect to the peripheral surface of the photoconductor drum 10.

Each of the developing devices 13 is a charger 1 as described above.
The electrostatic latent image formed on the photosensitive drum 10 by the charging by 1 and the image exposure by the exposure optical system 12 is reversely developed in a non-contact state by applying a developing bias voltage.

Next, the process of the color image forming apparatus in this apparatus will be described.

The original image is temporarily read as an image signal for each color of Y, M, C and K from an image read by an image pickup device or an image edited by a computer in an image reading apparatus separate from this apparatus. Stored and stored in memory.

When the image recording is started, the photoconductor drive motor is rotated to rotate the photoconductor drum 10 clockwise.
At the same time, application of electric potential to the photoconductor drum 10 is started by the charging action of the charger 11 (Y).

After a potential is applied to the photosensitive drum 10, the exposure optical system 12 (Y) starts image exposure with an electric signal corresponding to a first color signal, that is, a yellow (Y) image signal, and the drum is started. An electrostatic latent image corresponding to the yellow (Y) image of the original image is formed on the photosensitive layer on the surface by the rotational scanning of.

The latent image is reversely developed by the developing device 13 (Y) with the developer on the developing sleeve in a non-contact state, and a yellow (Y) toner image is formed according to the rotation of the photosensitive drum 10.

Next, the photosensitive drum 10 is further given a potential on the yellow (Y) toner image by the charging action of the charger 11 (M), and the second color signal of the exposure optical system 12 (M), that is, Image exposure is performed by an electric signal corresponding to the magenta (M) image signal, and non-contact reversal development by the developing device 13 (M) causes the magenta (M) toner on the yellow (Y) toner image. The images are sequentially superimposed and formed.

By the same process, the charger 11 (C),
The cyan (C) toner image corresponding to the third color signal is further generated by the exposure optical system 12 (C) and the developing device 13 (C), and finally, the charger 11 (K) and the exposure optical system 12 are used.
(K) and the developing device 13 (K) sequentially form a black (K) toner image corresponding to the fourth color signal, and the color image is formed on the peripheral surface of the photosensitive drum 10 within one rotation. A toner image is formed.

Thus, the color toner image formed on the peripheral surface of the photoconductor drum 10 is a transfer material which is a transfer material which is conveyed from the paper feed cassette 15A in the transfer device 14A and is synchronously fed by the driving of the timing roller 16A. Transferred to paper.

In the case of the one-sided copy, the transfer paper having the transferred toner image is separated from the drum peripheral surface by being removed of the charge in the static eliminator 14B and is fused with the toner in the fixing device 17 via the conveyor belt 20. The discharge roller 18
It is discharged onto the tray on the upper part of the device via the.

In the case of double-sided copying, the transfer paper which has once passed through the fixing device 17 moves to the positions indicated by the chain double-dashed line with the conveyor belt 20 and the fixing guide plate 21, and at the same time, the fixing roller 17A and the respective conveying rollers R1 , R
By reversing the rotation directions of 2 and R3, the paper is fed back from the fixing device 17 and fed into the reversing paper feed path 22. The transfer paper is reversed through the reverse paper feed path 22 and merges with the paper feed path from the paper feed cassette 15 again, and then the transfer paper is reversed again through the timing roller 16A to receive the image on the back surface, and the transfer belt 20 and the fixing guide are transferred. Returning plate 21 to the initial position and fixing roller 17
The image on the back side is fixed by switching A and the transport rollers R1 and R2 to the normal rotation, and the image is recorded on both sides and then discharged.

On the other hand, the photosensitive drum 10 from which the transfer paper is separated
The cleaning device 19 removes and cleans residual toner to continue forming the toner image of the original image, or temporarily stops and waits for formation of a new toner image of the original image.

In FIG. 2, the base of the photoconductor drum 10 is formed of a transparent member, and each exposure optical system 12 is arranged so as to face the inner peripheral surface of the base. A color image forming apparatus configured to perform image exposure is shown, and members having the same function are indicated by the same reference numerals as those of the above-described apparatus.

The photosensitive drum 10 used in this apparatus is
An organic photosensitive layer (OPC) made of a transparent conductive layer is applied to the outer periphery of a substrate formed of a transparent member such as optical glass or transparent acrylic resin, and is rotated clockwise in a state where the transparent conductive layer is grounded. .

Reference numeral 11 denotes a scorotron charger, which is a charging means. The scorotron charger 11 performs a charging operation on the above-described organic photosensitive layer of the photosensitive drum 10 by a grid held at a predetermined potential and corona discharge by a discharge wire. A uniform electric potential is applied to the drum 10.

Reference numeral 12 denotes an exposure optical system which is an image exposure means, and includes LEDs, FL, E arranged in the axial direction of the photosensitive drum 10.
It is composed of light emitting elements such as L and PL and a SELFOC lens as a unity magnification imaging element. The image signals of the respective colors read by the separate image reading device are sequentially taken out from the memory and input as electric signals to the respective exposure optical systems 12. The emission wavelength of the light emitting device used in this example is 680 nm.

Each of the exposure optical systems 12 is mounted on a columnar support member 40 and accommodated inside the base of the photosensitive drum 10. The exposure optical system 12 may be composed of a combination of an optical shutter member such as LCD, LISA, PLZT and the like, and an image forming lens such as a SELFOC lens, in addition to the above light emitting element.

13 is yellow (Y), magenta (M),
A developing device, which is a developing unit that contains cyan (C) and black (K) developers, is provided with a developing sleeve 130 that rotates in the same direction with a predetermined gap from the peripheral surface of the photosensitive drum 10. ing.

Each of the developing devices 13 is the charging device 1 described above.
The electrostatic latent image formed on the photosensitive drum 10 by the charging by 1 and the image exposure by the exposure optical system 12 is reversely developed in a non-contact state by applying a developing bias voltage.

The formation and recording of images by this apparatus are performed by the same process as that of the above-mentioned apparatus.

The photosensitive drum 10 of the apparatus shown in FIG. 1 is a cylindrical member which is longer in the axial direction than the width of the recording paper to be transferred, and the flange members 10 are provided on both side ends thereof as shown in FIG.
A and 10B are engaged and integrated with each other, and are rotatably supported and supported by a drum shaft 110 provided between the substrates of the apparatus.

The flange member 10B is integrally formed with a large gear G2 that meshes with a drive gear G1 on the main body side of the apparatus, and is driven and rotated in a predetermined direction by the power of the main body side.

On the other hand, in the case of the photosensitive drum 10 of the apparatus shown in FIG. 2, the above-mentioned flange members 10A and 10B have a structure in which they are directly supported by bearings on the substrate of the apparatus because of the relationship of including the exposure optical system 12. Similarly, in the photoconductor drum 10, the large gear G2 of the flange member 10B is driven and rotated by the rotation of the drive gear G1.

An embodiment of the present invention will be described below with reference to a color image forming apparatus shown in FIG. 2 in which each exposure optical system 12 is arranged inside a photosensitive drum 10.

(Embodiment 1) In the color image forming apparatus of the present invention, as shown in FIG. 4, the developing device 13 (Y) and the cleaning device 19 are provided on the right peripheral surface facing the left peripheral surface of the photosensitive drum 10. Facing the developing units 13 (M), 13 (C) and 1
It is also possible to dispose 3 (K), whereby the feeding direction of the recording paper from the image transfer area to the fixing device 17 can be configured to be substantially horizontal, and the transport condition can be improved.

As shown in FIG. 6, the number of teeth of the drive gear G1 is Z1, and the large gear G corresponding to the central angle formed by each exposure optical system.
The number of teeth is set to be the same or an integral multiple of the number of teeth Z1 of the drive gear G1, and the central angle of each exposure optical system with respect to the drum is set.

Therefore, the drive gear G1 has pitch unevenness or eccentricity in a part of the tooth profile which constitutes the drive gear G1 and causes uneven feeding in the photosensitive drum 10 during image exposure in the rotational direction, that is, the sub-scanning direction in image scanning, and each latent image formed. Even if the image has periodic image distortion or pitch unevenness on the scanning line, since such distortion and pitch unevenness are generated at the same position on each latent image screen, each latent image is accurately superimposed. To be done.

As a result, in each toner image formed by development, color registration is accurately performed even in a portion where image distortion or pitch unevenness on the scanning line is normal, so that color misregistration or color difference occurs. It is possible to provide a high-quality color image without unevenness.

In this case, the exposure optical systems 12 (M) and 12 (C) and 12 (C) and 1 (C) correspond to the position of the developing device with respect to the rotation center of the photosensitive drum 10.
2 (K) have the same central angle θ and the exposure optical system 12
(Y) and 12 (M) are arranged at a position forming a central angle 2θ that is twice as large as that. In the embodiment, the central angle between the exposure optical systems is 1: 2, but it is also possible to set a proportional relationship such as 2: 3 or 3: 4.

As a result, as shown in FIG. 6, the number of teeth of the drive gear G1 is Z1, the number of teeth of the large gear G2 is Z2, and the large gear G2 corresponding to the central angle θ formed by each exposure optical system described above.
When the number of teeth of the drive gear G1 is Z3, the number of teeth Z2 of the large gear G2 is set to an integral multiple (k times) of the number of teeth Z1 of the drive gear G1, and the number of teeth Z3 is further set to the number of teeth Z1 of the drive gear G1. It is possible to set the values of the central angle θ and the central angle 2θ with respect to the drum of each tooth number configuration and each exposure optical system so as to be the same or an integral multiple (m times).

Therefore, the drive gear G1 is formed by causing unevenness in pitch or eccentricity in a part of the tooth profile that constitutes the drive gear G1 and causing unevenness in feed in the rotational direction of the photosensitive drum 10 during image exposure, that is, in the sub-scanning direction in image scanning. Even if the latent image has periodic image distortion or uneven pitch on the scanning line,
Since such distortion and pitch unevenness are generated at the same position on each latent image screen, the latent images are accurately superimposed.

As a result, in each toner image formed by development, color registration is accurately performed even in a portion where image distortion and pitch irregularity on the scanning line are the same as in a normal portion. It is possible to provide a high-quality color image without unevenness.

Further, since the number of teeth Z2 is an integral multiple of the number of teeth Z1, even if there is uneven feeding, the position where the unevenness occurs is specified at a position where the phase of the rotation cycle of the photosensitive drum 10 is the same. The effect does not appear as a superposed image.

In FIG. 8, after the initial position d0 of occurrence of uneven feeding is specified by the rotation phase of the drum, the number of teeth Z3 is changed to the number of teeth Z1.
By the same or more integer times (k times), the same position d1 of occurrence of the feed unevenness for each image exposure cycle, and each toner of Y, M, C, and K formed by each image exposure. It shows an example in which any image can be accurately superimposed on the image such as image distortion or pitch unevenness on the scanning line.

(Second Embodiment) The color image forming apparatus of the present invention temporarily transfers the toner image formed on the photosensitive drum 10 to the intermediate transfer belt 14 as shown in FIG. It is also possible to adopt an intermediate transfer system in which the image is transferred onto a recording paper sandwiched between the transfer roller 15 and thereby, the developing devices 13 (Y) and 13 (M) are provided on the left peripheral surface of the photosensitive drum 10. Developing device 13 on the right side
By arranging (C) and 13 (K) in symmetrical positions with respect to each other with good balance, it is possible to improve the conditions of operation and maintenance.

As shown in FIG. 7, the number of teeth of the drive gear G1 is Z1, and the large gear G corresponding to the central angle formed by each exposure optical system.
The number of teeth is set to be the same or an integral multiple of the number of teeth Z1 of the drive gear G1, and the central angle of each exposure optical system with respect to the drum is set.

Therefore, the drive gear G1 has pitch unevenness or eccentricity in a part of the tooth profile which constitutes the drive gear G1 and causes unevenness in feed in the rotational direction of the photosensitive drum 10 during image exposure, that is, in the sub-scanning direction in image scanning. Even if the image has periodic image distortion or pitch unevenness on the scanning line, since such distortion and pitch unevenness are generated at the same position on each latent image screen, each latent image is accurately superimposed. To be done.

As a result, in each toner image formed by development, color registration is accurately performed even in a portion where image distortion or pitch unevenness on the scanning line is normal, so that color misregistration or color difference occurs. It is possible to provide a high-quality color image without unevenness.

In this case, each exposure optical system corresponds to the arrangement position of the developing device and the exposure optical systems 12 (Y) and 12 (M) and 12 (C) and 1 with respect to the rotation center of the photosensitive drum 10.
2 (K) have the same central angle φ and the exposure optical system 12
(M) and 12 (C) are arranged at a position forming a central angle 2φ twice that. In the embodiment, the central angle between the exposure optical systems is 1: 2, but it is also possible to set a proportional relationship such as 2: 3 or 3: 4.

As a result, as shown in FIG. 7, the number of teeth of the driving gear G1 is Z1, the number of teeth of the large gear G2 is Z2, and the large gear G corresponding to the central angle φ formed by each exposure optical system described above.
When the number of teeth of 2 is Z3, the number of teeth Z2 of the large gear G2 is set to an integral multiple (k times) of the number of teeth Z1 of the drive gear G1, and the number of teeth Z3 is further set to the number of teeth of the drive gear G1. It is possible to set the values of the central angle φ and the central angle 2φ with respect to the drum of each tooth configuration and each exposure optical system so that they are the same as or an integral multiple (n times) of Z1.

As a result, also in the present embodiment, as in the case of the first embodiment described above, a high-quality color image without color misregistration or color unevenness is provided, and even if uneven feeding occurs, the occurrence position is exposed. It is possible to specify the positions where the phases of the rotation cycles of the body drums 10 are the same, and the effect does not appear as a superimposed image.

In FIG. 9, the number of teeth Z2 is an integer multiple of the number of teeth Z1 (k
By setting the number of teeth Z3 to an integer multiple (n times) of the number of teeth Z1 to specify the initial position d2 of the occurrence of uneven feeding with respect to the rotation period of the photosensitive drum 10, An example is shown in which, at the same position d3 where unevenness occurs, any color image formed by this image forming apparatus can record image distortion or deformation at a specified common position on the image. Is.

Further, in the first and second embodiments, the number of teeth Z2
Is preferably an integral multiple of the number of teeth Z3.

The drive gear G1 in the first and second embodiments
However, if it is configured to be rotated by the drive motor through a reduction gear, a combination of gears with an integer number of teeth is used as the reduction gear in order to prevent long cycle pitch unevenness and eccentricity. Is preferred.

[0059]

According to the present invention, it is possible to specify the cycle in which fluctuations in the rotational speed of the image forming body due to pitch unevenness and eccentricity of the drive gear occur, and the resulting distortion and scanning of each image. Since the pitch unevenness on the line is restricted to the same specified portion on the image, a color image forming apparatus capable of forming a high-quality image by guaranteeing the registration accuracy of image superposition is provided. It became a thing.

[Brief description of drawings]

FIG. 1 is a sectional configuration diagram of a color image forming apparatus (No. 1) of the invention.

FIG. 2 is a sectional configuration diagram of a color image forming apparatus (No. 2) of the invention.

FIG. 3 is a cross-sectional configuration diagram of a photosensitive drum.

FIG. 4 is a configuration example (1) of an image forming unit.

FIG. 5 is a configuration example (2) of the image forming unit.

FIG. 6 is a layout example (1) of the exposure optical system.

FIG. 7 is a layout example (2) of the exposure optical system.

FIG. 8 is a diagram showing a position where uneven feeding occurs in the first embodiment.

FIG. 9 is a diagram showing a position where uneven feeding occurs in the second embodiment.

[Explanation of symbols]

10 Photosensitive drum 10A, 10B Flange member 11 charger 12 Exposure optical system 13 Developer 14 Intermediate transfer belt 14A transfer device 14B static eliminator 15 Transfer roller 15A paper feed cassette 16A timing roller 17 Fixing device 18 Paper ejection roller 19 Cleaning device 110 drum shaft G1 drive gear G2 gear

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masayasu Onodera 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica Co., Ltd. (72) Inventor Toshihide Miura 5-14-14 Midorimachi, Koganei-shi, Tokyo (56) References JP-A-6-35285 (JP, A) JP-A-5-307307 (JP, A) JP-A-9 -174922 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03G 15/00 550 G03G 21/16-21/18 G03G 15/01-15/01 117

Claims (2)

(57) [Claims] 1. A charging means for performing a plurality of chargings, an image exposing means for forming a latent image, and the latent image being visualized on a peripheral surface of an image forming body rotated by driving a gear. A color image in which a developing unit is provided and the toner image is formed by superposing the toner image by repeating charging, image exposure and development during one rotation of the image forming body, and then collectively transferring the toner image to a transfer material. In the forming apparatus, the large gear integrally fixed to the image forming body is the large gear.
To rotate the image forming body by engaging with a drive gear for driving the
The large tooth between the plurality of image exposure positions on the peripheral surface of the image forming body is configured to be rotated.
The number of teeth on the car is an integer multiple of the number of teeth on the drive gear.
And the number of teeth of the large gear between the image exposure positions is the same.
The color image forming apparatus is characterized by excluding the case . 2. The number of teeth of the large gear is the number of teeth of the drive gear.
2. The color image forming apparatus according to claim 1 , wherein the color image forming apparatus is a multiple of.