JPH07301980A - Image forming device - Google Patents

Abstract

PURPOSE:To surely perform the side erasing of transfer paper and to accurately form an image only in an specified area on the transfer paper by detecting the positional deviation of the transfer paper on a carrying path in a direction orthogonal to the carrying direction thereof and shifting the light emitting position of an eraser in the direction orthogonal to the carrying direction corresponding to the detected positional deviation. CONSTITUTION:The position detection signal of a CCD 29 being a lateral resist detecting device is given to a CPU 38 through an I/O interface 41, and the CPU 38 calculates the position of the transfer paper on the carrying path based on the signal and calculated required erasing width from the reference line of a mechanical system corresponding to the calculated position. When the erasing width is secured by the eraser 24 at a current position, the erasing width equal to the secured amount on the eraser 24 is calculated and given to a lighting control circuit 40. When the required erasing width from the reference line of the mechanical system can not be secured by the eraser 24 at the current position, eraser shift quantity by which the erasing width can be secured is calculated. A controller 39 is instructed to drive and rotate a stepping motor 32 by as much as the calculated eraser deviation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus, and more particularly to control of an image forming position on a transfer sheet.

[0002]

2. Description of the Related Art For example, in a copying machine that projects an image of an original onto a photosensitive member through an optical system, the original is misaligned on a contact glass plate, the projection position of the optical system is misaligned, and the transfer paper is transferred to a transfer device. Image misregistration occurs on the transfer paper due to misalignment of the sheet feeding. In a conventional copying machine, by providing side erase of the transfer paper, it is possible to prevent the document from being scratched or the image outside the document from appearing on the copy, and the untransferred toner other than the transfer paper is left on the drum. However, the excessive load on the cleaning and the wasteful discharge of the toner are prevented. However, in an actual machine, there are variations in the projection position of the original image, variations in the transfer paper position, variations in the erase position, etc. Therefore, even though the original variations were to be erased as narrowly as possible, To allow for extra space, I applied wider erase than necessary. In addition, in order to deal with these problems, JP-A-60-
In Japanese Patent No. 186451, an eraser is provided so as to be movable in a direction parallel to the axis of the photosensitive drum, that is, a direction orthogonal to the transport direction of the transfer paper, and the electrostatic latent image before transfer is based on the exposure optical axis. A static eliminator that adjusts the position of the eraser so as to limit it to a predetermined area has been proposed. Japanese Patent Laid-Open No. 60-1613
Japanese Patent Publication No. 67 proposes a copying machine that detects the position of a document and adjusts the eraser position in accordance with the position of the document.

[0003]

However, in recent copying machines, it is always the case that a plurality of trays for stacking transfer paper are also provided, and the deviation of the paper feeding position differs for each tray, and the original or the exposure optical axis reference. With the erase position adjustment, the adjustment of the image area on the transfer paper is no longer sufficient.

Therefore, the first object of the present invention is to ensure the side erase of the transfer paper, and the second object is to accurately form an image only in a predetermined area on the transfer paper.

[0005]

According to the present invention, a photoconductor, a charger for charging the photoconductor, an exposure device for exposing the charged surface of the photoconductor with image light, and an electrostatic latent image formed by the exposure are visualized. In the image forming apparatus, a developing device, a transfer unit for transferring a visible image to a transfer sheet, a transfer unit for transferring the transfer sheet to the transfer unit, and an eraser for erasing unnecessary portions of the electrostatic latent image are provided. A lateral registration detecting device for detecting a positional deviation of a transfer sheet on a conveying path of the conveying means in a direction orthogonal to the conveying direction, and a position of the eraser corresponding to the detected positional deviation in a direction orthogonal to the conveying direction. An erasing position adjusting means for shifting the light emitting position is provided.

[0006]

The lateral registration detecting device detects the positional deviation of the transfer paper on the conveying path for feeding the transfer paper to the transfer means in the direction orthogonal to the conveying direction, and the erasing position adjusting means responds to the detected positional deviation. The light emitting position of the eraser in the direction orthogonal to the carrying direction is shifted. As a result, a side erase having a predetermined width is performed on the transfer paper, and an image is accurately formed only in a predetermined area.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0008]

FIG. 1 shows an embodiment of the present invention. The original 2 on the contact glass 1 is illuminated by the exposure lamp 3,
The image of the original document 2 includes the first to sixth mirrors 4 to 9 and the lens 10.
Is projected onto the photoconductor 11. Photoconductor drum 11
Is charged by the charging charger 12 and an image (optical image) is projected by the above-described optical system, and then developed by the developing device 13. As a result, an image (toner image) appears on the photosensitive drum 11. On the other hand, the transfer papers 15 are sent out one by one from a paper feed tray (two stages in this embodiment) 14 by a calling roller 16 and a separating unit 17, and are transferred via a registration roller 18 to a transfer charger 19 and a photosensitive drum. It is fed during 11, and by the transfer charger 19,
The toner image on the photosensitive drum 11 is transferred to the transfer paper 15. The transfer paper on which the toner image is placed is the separation charger 20.
Then, the toner image is separated from the photosensitive drum 11 and sent to the fixing unit 21, where the toner image is fixed. The transfer paper on which the fixing process is completed is discharged to the paper discharge tray 22. An eraser 24 erases the charging potential in the non-image area on the photosensitive drum 11.

Transfer charger from the registration roller 17
A horizontal registration detecting device 25 for detecting the end (transverse registration) position of the transfer paper (position in the direction perpendicular to the paper surface of FIG. 1) is provided in the transfer path of the transfer paper 15 up to 19. It is advantageous to detect the lateral registration at a position as close to the transfer charger 19 as possible in order to accurately perform side erase on the transfer paper. (In the clockwise direction), the eraser 24 is considerably upstream of the transfer charger 19, and the length from the eraser 24 to the transfer charger 19 along the peripheral surface of the photosensitive drum 11 is measured. Minutes or more, transfer charger-1
It is necessary to detect the lateral resist at a position farther than 9.

FIG. 2 shows the configuration of the lateral registration detecting device 25. In this embodiment, the lever 2 that contacts the end of the transfer paper
6 is used. The lever 26 is rotatable around a fulcrum 27 and is pressed against the end of the transfer paper by a spring 28. Reference numeral 29 denotes a CCD, and a part of light emitted from a light source (not shown) above the paper surface to the CCD 29 is blocked by the lever 26. Therefore, the rotation position of the lever 26 is detected by the CCD 29, and this is converted into the transfer paper edge.

FIG. 3A shows the appearance of the eraser 24, and FIG. 3B shows a part of the light emitting end face of the eraser 24 in an enlarged manner. The eraser 24 includes a large number of partitions 30 and LEDs.
31 and selectively turn on their LEDs 31
By turning on / off, it is possible to finely switch the irradiation width.

FIGS. 4 and 5 show a mechanism for driving the eraser 24 in the direction along the drum axis (direction orthogonal to the transfer paper conveyance direction). 32 is a stepping motor,
The lever 34 is rotationally driven via the gear 33 fixed to the shaft. In FIGS. 4 and 5, when the lever 34 rotates clockwise, the eraser 24 moves the compression coil spring 3
5 is driven to the left by the repulsive force of FIG. 5, and when the lever 34 rotates counterclockwise, the eraser 24 is driven to the right in FIG. 5 and the coil spring 35 is compressed. Therefore, by driving the motor 32 forward and backward, the lever 34 rotates clockwise and counterclockwise, and the eraser 24
Moves forward (left in FIG. 5) and backward (right in FIG. 5) in the drum axis direction.

FIG. 6 shows the electrical system of the copying machine shown in FIG.
An outline of parts related to the implementation of the present invention will be shown. Based on the data in ROM36 and RAM37, CPU3
Controlled by 8. The stepping motor 32 is driven by a driver controller 39, and the eraser 24 is driven by a lighting control circuit 40.
9 and the control circuit 40, the 1/0 interface 41
The CPU 38 provides control data via the. CPU3
A position detection signal of the CCD 29 of the lateral registration detection device 25 is given to 8 via the 1/0 interface. The CPU 38 calculates the position of the transfer sheet from the position detection signal, and first calculates the required erase width from the reference line of the mechanical system corresponding to the position of the transfer sheet. When this eraser width can be secured by the eraser 24 at the current position, the eraser width (the number of LEDs to be turned on) on the eraser 24 is calculated and the lighting control is performed. It is given to the circuit 40. The required erase width from the mechanical system reference line is
When it cannot be secured by the server 24, an eraser shift amount that can secure it is calculated, and the controller 39 is instructed to rotate the stepping motor 32 accordingly, and the shift amount of the eraser 24 is calculated. At, the required erase width on the eraser is calculated and given to the lighting control circuit 40. That is, the CPU 38 causes the required shift amount of the eraser 24 and the required eraser on the eraser to correspond to the transfer sheet position.
Controller 39 and lighting control circuit 4
The position and erase width of the eraser 24 are controlled via 0.

According to the embodiment of the present invention described above,
Since the erase width of the eraser 24 is controlled according to the position of the transfer paper, proper erase can be achieved at low cost. Further, since the erase width is controlled by adjusting the position of the eraser 24, it is possible to change the erase position minutely, so that more appropriate erase can be achieved.

[0015]

EFFECTS OF THE INVENTION Since the lateral registration position of the transfer paper is detected and the erase position is changed correspondingly, the latent image potential is erased at the proper position, and the visible image area is accurately positioned with respect to the transfer paper. become.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a mechanical element according to an embodiment of the present invention.

FIG. 2 is an enlarged plan view showing the configuration of a lateral registration detection device 25 shown in FIG.

3A is an enlarged perspective view of the eraser 24 shown in FIG. 1, and FIG. 3B is an enlarged front view of a part of a light irradiation end surface of the eraser 24.

FIG. 4 is a perspective view showing a mechanism for driving the eraser 24 shown in FIG. 1 for displacement adjustment.

5 is a plan view showing a mechanism for driving the eraser 24 shown in FIG. 1 for displacement adjustment.

FIG. 6 is a block diagram showing an electric system related to the implementation of the present invention in the copying machine shown in FIG.

[Explanation of symbols]

1: Contact glass 2: Original 3: Exposure lamp 4-9: 1st-6th
Mirror 10: Lens 11: Photosensitive drum 12: Charger charger 13: Development 14: Paper feed tray 15: Transfer paper 16: Calling roller 17: Separation part 18: Registration roller 19: Transfer charger 20: Separation charger 21: Fixing unit 22 : Paper ejection tray 24: Eraser 25: Lateral registration detector 26: Lever 27: Support 28: Spring 29: CCD 30: Partition 31: LED 32: Stepping motor 33: Gear 34: Lever 35: Spring 36: ROM 37: RAM 38: CPU 39: Driver controller 40: Lighting control circuit

Claims (3)

[Claims] 1. A photoconductor, a charger for charging the photoconductor, an exposure device for exposing the charged surface of the photoconductor with image light, a developing device for visualizing an electrostatic latent image formed by the exposure, and a transfer of the visual image. In an image forming apparatus having a transfer unit for transferring to a paper, a transfer unit for transferring the transfer sheet to the transfer unit, and an eraser for erasing unnecessary portions of the electrostatic latent image, transfer of a transfer path of the transfer unit. A lateral registration detecting device for detecting a positional deviation of the paper in a direction orthogonal to the carrying direction, and an erasing position adjusting means for shifting the light emitting position of the eraser in a direction orthogonal to the carrying direction corresponding to the detected positional deviation. An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, wherein the erasing position adjusting means is a lighting control means for adjusting the number of lights of a plurality of light emitting elements arranged in a direction orthogonal to the transport direction of the eraser. 3. The erasing position adjusting means comprises drive means for driving the eraser in a direction orthogonal to the carrying direction and drive control means for controlling drive of the eraser by the drive means. Image forming device.