JP2003307900A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect the soiling of a registration sensor. <P>SOLUTION: The image forming apparatus is provided with a means in which a slit is provided in the non-image area of an intermediate transfer body and a reflector is installed on the extension of the registration sensor and the slit, and by which the soiling of the registration sensor is discriminated according to the output of the registration sensor at the slit part, a means for postponing registration correction control until the registration sensor is cleaned when the registration sensor is soiled, and a means for preserving a correction value calculated by the registration correction control in a non-volatile memory. <P>COPYRIGHT: (C)2004,JPO

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 such as a copying machine such as an electrophotographic system or an electrostatic storage system, a printer, and the like, and more particularly, to each image formed by a plurality of image forming units arranged side by side. It is useful when applied to a color image forming apparatus that forms a superimposed image by sequentially transferring onto an intermediate transfer member.

[0002]

2. Description of the Related Art A plurality of image forming portions for irradiating a photosensitive drum with a laser to develop an electrostatic latent image on a photosensitive body by an electrophotographic process and transfer the electrostatic latent image onto the intermediate transfer body are provided. 2. Description of the Related Art There is known a device that superimposes and transfers images to obtain a color image. When using this type of image forming apparatus, the electrostatic latent image formed on each photosensitive drum is transferred onto the intermediate transfer body due to mechanical attachment error of each photosensitive drum, optical path length error of each laser beam, optical path length change, etc. There is a problem that the registration of each color will not match when transferred to. For this reason, conventionally, the registration correction pattern image formed on the intermediate transfer member from each photosensitive drum is read by a photo sensor, a CCD sensor, or the like, and a registration deviation on the photosensitive drum corresponding to each color is detected and recorded. The image signal to be processed is mechanically or electrically corrected.

[0003]

However, an optical sensor for detecting a registration correction pattern image on the surface of an intermediate transfer member is contaminated with a developer or the like in proportion to the number of printed sheets, or is subjected to JAM processing or the like. There is a possibility that the optical sensor may be soiled by mistake.

If the optical sensor is soiled, there is a problem that the registration correction cannot be performed accurately and the registration deviation of each color cannot be corrected.

The present invention has been made in view of the above-mentioned prior art. When the dirt of the optical sensor is detected and it is determined that the optical sensor is dirty, the registration correction control is not executed and the The purpose is to defer registration correction control until the optical sensor is cleaned.

[0006]

In order to solve this problem, the present invention provides a latent image forming means for forming a latent image by scanning a photosensitive member with a modulated laser beam by an optical scanning system.
Developing means for developing a latent image formed on the photoconductor with a developer, an intermediate transfer body for transferring the developer image formed at each image forming station, and toner transferred to the intermediate transfer body. A transfer unit configured to transfer an image to a transfer material, the detection unit detecting an image transferred on the intermediate transfer member with an optical sensor (hereinafter referred to as a "registration sensor"); Correction means for correcting the registration of each image forming station based on the detection result of the detection means (hereinafter referred to as "registration correction control"); means for storing the detection result of the detection means in a non-volatile memory; If the registration sensor is judged to be dirty, and if the registration sensor is judged to be dirty, the registration correction control is postponed and Acquires the previous detection result from sexual memory, the image forming apparatus characterized by comprising means for forming an image.

The present invention can be summarized in the following configurations if it is summarized and summarized above.

(1) A latent image forming means for forming a latent image by scanning the photoconductor with a modulated laser beam by an optical scanning system, and a latent image formed on the photoconductor with a developer. In an image forming apparatus in which image forming stations having developing means for converting the image forming stations are arranged side by side for developing colors, an intermediate transfer body for transferring the developer image formed at each image forming station is provided, and the image is transferred onto the intermediate transfer body. Detection means for detecting a predetermined image, correction means for correcting the registration of each image forming station based on the detection result of the detection means,
A registration including a slit on the surface of the intermediate transfer member, a reflection plate inside the intermediate transfer member, and a light emitting unit for irradiating the surface of the intermediate transfer member with light and a light receiving unit for receiving the light reflected by the intermediate transfer member. An image forming apparatus comprising: a sensor unit; and a registration sensor stain detection unit that detects that the registration sensor is soiled by the output of the registration sensor unit.

(2) If the registration sensor dirt detection means determines that the registration sensor is dirty, the registration sensor dirt reporting means is provided with a reporting means for reporting to the user that the registration sensor is dirty. The image forming apparatus according to (1) above.

(3) Means for storing the correction value calculated by the correction means for correcting the registration of each image forming station in a non-volatile memory, and the registration sensor dirt detection means for soiling the registration sensor. The image forming apparatus according to (1) or (2) above, further comprising: a unit that obtains a correction value from the non-volatile memory and forms an image when it is determined that the image is formed.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) An embodiment of the present invention will be described with reference to the following drawings.

Referring to FIG. 1, an outline of the overall configuration of a laser printer as a multicolor image forming apparatus according to an embodiment of the present invention will be described.

As shown in FIG. 1, the laser blinter forms an electrostatic latent image with image light formed based on an image signal obtained by scanning an original in an image forming section, and develops the electrostatic latent image to develop a visible image. Are superimposed and transferred to form a color visible image, the color visible image is transferred to the transfer material 2, and the color visible image on the transfer material 2 is fixed. The image forming unit is a station arranged in parallel for developing colors. Each photoconductor (5
Y, 5M, 5C, 5K), injection charging means (7Y, 7M, 7C, 7K) as primary charging means, developing means (8Y,
8M, 8C, 8K), toner cartridge (11Y, 1
1M, 11C, 11K), an intermediate transfer body 12, a sheet feeding section, a transfer section, and a fixing section 13.

Photosensitive drums (photosensitive members) 5Y, 5M, 5
C and 5K are configured by applying an organic photoconductive layer on the outer periphery of an aluminum cylinder, and are rotated by transmitting the driving force of a drive motor (not shown).
M, 5C, and 5K are rotated counterclockwise according to the image forming operation. The exposure light to the photosensitive drums 5Y, 5M, 5C, and 5K is sent from the scanner units 10Y, 10M, 10C, and 10K, and the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K are selectively exposed to electrostatic latent images. The image is configured to be formed.

As the primary charging means, four injection chargers 7Y, 7M and 7C for charging yellow (Y), magenta (M), cyan (C) and black (K) photoconductors for each station. , 7K, and each injection charger is provided with a sleeve 7YS, 7MS, 7CS, 7KS.

As developing means, four developing devices for developing yellow (Y), magenta (M), cyan (C), and black (K) at each station in order to visualize the electrostatic latent image. 8Y, 8M, 8C, 8K, and each developing device has a sleeve 8YS, 8MS, 8CS,
8CK is provided. Each developing device is detachably attached.

The intermediate transfer member 12 includes the photosensitive drums 5Y and 5Y.
The photosensitive drums 5Y, 5M, 5C, and 5K are in contact with M, 5C, and 5K and rotate clockwise when forming a color image.
It rotates with the rotation of K and receives the transfer of a visible image. Further, the intermediate transfer body 12 is brought into contact with a transfer roller 9a, which will be described later, at the time of image formation, and nips and conveys the transfer materials 2 and 4, so that a color visible image is simultaneously superimposed and transferred onto the transfer materials 2 and 4 on the intermediate transfer body 12. To do.

The transfer roller 9a is brought into contact with the intermediate transfer member while the color visible image is being transferred on the intermediate transfer member 12 in a superimposed manner, but is separated to the position 9b when the printing process is completed.

The fixing unit 13 is for fixing the transferred color visible image while the transfer material 2 is being conveyed. The fixing roller 1 heats the transfer material 2 as shown in FIG.
4 and a pressure roller 15 for bringing the transfer material 2 into pressure contact with the fixing roller 14. The fixing roller 14 and the pressure roller 15 are formed in a hollow shape, and the heater 1 is provided inside thereof.
6 and 17 are built in. That is, the transfer material 2 holding the color visible image is the fixing roller 14 and the pressure roller 15.
And the toner is fixed on the surface by applying heat and pressure.

The transfer material 2 on which the visible image has been fixed is then discharged to a paper discharge unit (not shown) by a discharge roller (not shown) to complete the image forming operation.

The cleaning means 21 is a photosensitive drum 5.
Y, 5M, 5C, 5K and the toner remaining on the intermediate transfer body 12 are cleaned by the photosensitive drum 5Y,
After the visible image formed by the toners formed on 5M, 5C, and 5K is transferred to the intermediate transfer body 12, the waste toner or the four-color visible image formed on the transfer roller 9 is transferred to the transfer material 2. The waste toner is stored in the cleaner container.

FIG. 2 is a schematic view of the intermediate transfer body 12.
The intermediate transfer body 12 is formed of a rubber belt or a resin belt, and the photosensitive drums 5 of the respective colors are formed around the intermediate transfer body 12.
Registration sensors 6A and 6B for reading registration correction pattern images formed on the intermediate transfer member 12 from Y, 5M, 5C, and 5K are provided.

Lasers 10Y, 10M, 10C, and 10K are irradiated onto the photosensitive drums 5Y, 5M, 5C, and 5K, and electrostatic latent images on the photosensitive members 5Y, 5M, 5C, and 5K are developed by an electrophotographic process, and intermediate transfer is performed. In the case of an image forming apparatus that has a plurality of image forming portions to be transferred onto the body 12 and obtains a color image by superimposing and transferring the images of the respective colors onto the intermediate transfer body 12, the mechanical mounting error of each photosensitive drum and the laser beam Each photosensitive drum 5Y, 5M, 5 due to an optical path length error, an optical path length change, etc.
When an electrostatic latent image is formed on C and 5K and transferred onto the intermediate transfer body 12, there is a problem that the registration of each color will not match. Therefore, the photosensitive drums 5Y, 5M, 5
The registration correction pattern image formed on the intermediate transfer body 12 from C and 5K is a registration sensor 6A which is a pin photo sensor or a CCD sensor.
6B, the registration deviation on the photosensitive drum corresponding to each color is detected, and the image signal to be recorded is subjected to mechanical correction and electric correction.

A block diagram of a registration unit using a registration sensor is shown in FIG.

In this embodiment, the registration sensor is a pin photo sensor. The registration sensor unit 300A includes a light emitting unit 300, a light receiving unit 301, and a composite plastic lens 302. Light (hereinafter abbreviated as light source light) Io emitted from the light emitting unit 300 is reflected on the surface of the intermediate transfer body 12, and reflected light Ir is measured by the light receiving unit 301. The reflected light measured by the light receiving unit 301 is monitored by the LED light amount control unit 304 and sent to the CPU 305. CP
U305 is based on the measured values of the light source light Io and the reflected light Ir.
The mechanical attachment error of each photosensitive drum, the optical path length error of each laser beam, the optical path length change, etc. are calculated, and the image signal is subjected to mechanical correction and electrical correction.

FIG. 4 shows a flowchart of registration correction control. First, a registration correction pattern image is formed with the developer 1 on the surface of the intermediate transfer member (401). Subsequently, the correction pattern image (402) with the developer 2 and the correction pattern image (40 with the developer 3
3), a correction pattern image (404) of the developer 4 is formed (here, the developer 1, the developer 2, the developer 3, the developer 4).
Is one of yellow, magenta, cyan, and black).

After the color developer images are formed on the surface of the intermediate transfer member, the reflection density of each color developed image is measured by the registration sensors 6A and 6B (405). If it is determined from the measurement results that there is a main scanning width error (406),
If the image frequency is finely adjusted (407) and it is determined that there is a writing position error in the main scanning direction (408), the horizontal synchronization timing is finely adjusted (409). Further, when it is determined that there is a writing position error in the sub-scanning direction (410),
Finely adjust the phase of the polygon motor.

However, if the registration correction control is executed in a state where the registration sensors 6A and 6B are contaminated with a developer or the like, the output of the sensor is lowered and the registration correction pattern image cannot be read. It becomes impossible to detect the registration deviation for forming the original color image. Therefore, "registration sensor is not dirty" is a prerequisite for normally performing registration correction control.

The present invention has been made in view of the above-mentioned prior art. A slit portion is provided in the intermediate transfer member 12, a registration sensor 6A, 6B and a reflection plate are installed on the extension of the slit portion to perform registration. The purpose is to detect stains on the registration sensor by receiving the reflected light from the reflection plate by the sensor.

In order to achieve the above-mentioned target, a slit 501 (FIG. 5) is provided on the intermediate transfer body 12, and a reflection plate 502 (FIG. 5) is provided on the extension of the slit and inside the intermediate transfer.
The reflected light from the reflection plate 502 is measured by the registration sensor, and the contamination of the registration sensor is judged from the result.

FIGS. 6-1, 6-2, and 6-3 show the intermediate transfer member 12 in the case where the slit and the reflecting plate are provided. Figure 6-
1 is the intermediate transfer body 12 as seen from the direction of 204 (FIG. 2), and FIGS. 6-2 and 6-3 are the intermediate transfer body 12 as seen from the direction of 205 (FIG. 2).

The slits are provided in the non-image areas 201 and 202 of the intermediate transfer body 12. Slits 601A, 602A, 603A, 604A are provided on the non-image area 201 side, and slits 601B, 602B, 6 are provided on the non-image area 202 side.
03B and 604B are provided. A, B of each non-image area
The slit is located at a position orthogonal to the traveling direction of the intermediate transfer member (600).

The reflection plate is located inside the intermediate transfer body 12 on the extension of each slit (FIG. 6-2) or in the non-image areas 201, 20.
By being provided inside the intermediate transfer body 12 on the extension of the second registration sensors 6A and 6B (FIG. 6C), it is possible to prevent the reflection plate from being soiled by a developer or the like.

Intermediate transfer 1 in which the reflection plate is an extension of each slit 1
2 (FIG. 6-2), the reflection plate has a structure in which it is always on the extension of the slit as the intermediate transfer member rotates, and the registration sensors 6A in the non-image areas 201 and 202 are When it is provided inside the intermediate transfer body 12 on the extension of 6B, it does not depend on the rotation of the intermediate transfer body.
It is fixed and has a structure in which a reflection plate is always provided on the extension of the registration sensors 6A and 6B.

The registration sensors 6A and 6B are
It is determined whether the registration sensor is dirty or not based on the result of measuring the reflected light from the reflecting plate.

Considering the distance required to form a registration correction pattern image formed on the intermediate transfer body 12 by one registration correction control, slits are provided so that the intervals between the slits are equal. (Fig. 6
-2, Fig. 6-3).

FIG. 7 shows the relationship between the degree of contamination of the registration sensor and the sensor output of the reflected light from the reflector.
The horizontal axis shows the degree of contamination of the registration sensor.
From 01 to 702, the degree of contamination of the registration sensor is increasing. The vertical axis represents the sensor output when the reflected light from the reflection plate is received by the registration sensor, and indicates that the reflected light received by the registration sensor is stronger from 703 to 704.

The sensor output 700 decreases as the degree of contamination of the registration sensor increases, and eventually the registration correction pattern image cannot be detected.

The CPU 305 cannot recognize the registration correction pattern image due to the sensor output because the registration sensor becomes dirty (705).
At the border, the registration sensor is judged to be dirty (7
09). When it is determined that the registration sensor is dirty, the registration correction control is postponed, the user is notified that the registration sensor is dirty, and the cleaning of the registration sensor is prompted. CPU3
When 05 detects the opening and closing of the door that must be opened to clean the registration sensor, it checks whether the registration sensor has been cleaned, and if it determines that the registration sensor has been cleaned, it delays the registration correction. Execute control.

FIG. 8 shows a flow chart for detecting dirt on the registration sensor.

At the registration correction control timing, the registration sensor is turned on (801),
Monitor the output of the registration sensor (80
2). At this time, the intermediate transfer member is driven by the drive roller 18. When the slit portion can be detected from the sensor output (803), the registration sensor stain flag is cleared and registration correction control is executed (804, 805). When the slit portion cannot be detected while the intermediate transfer member is moving by the slit interval after turning on the registration sensor (80
In 6), the registration sensor determines that the sensor is dirty, postpones the registration correction control,
Set the registration sensor dirt flag (80
7) The user is notified that the registration sensor is dirty, and the user is prompted to clean the registration sensor (808).

When the registration sensor dirt flag is set and the opening / closing of the door that needs to be opened / closed to clean the registration sensor is detected regardless of whether the registration correction control timing is reached or not. The registration sensor stain detection is performed, and it is determined whether the registration sensor stain is removed, that is, whether the registration sensor is cleaned by the user. If it is determined that the registration sensor is cleaned, the registration correction is performed. The control is executed to apply the mechanical correction and the electrical correction calculated by the registration correction control to the image signal to be recorded.

As described above, it becomes possible to detect the contamination of the registration sensor, and it is possible to determine whether or not to execute the registration sensor correction control.

(Example 2) In Example 1, the intermediate transfer member 12 was used.
A slit and a reflector are provided in the non-image area, and it is judged whether the registration sensor is dirty or not by the output of the registration sensor. If it is judged that it is dirty, the registration correction control is postponed. Is to do.

When it is determined that the registration sensor is dirty, if the registration has been performed even once in the past, the image is formed with the correction value calculated by the registration correction control immediately before, so that the image is accurately formed. Even if the registration shift cannot be corrected, the image quality can be guaranteed to some extent. However, if it is determined that the sensor is soiled by the first registration sensor soiling detection after the power is turned on, the deviation of the registration is not corrected, and the expected image cannot be obtained.

In the second embodiment, means for correcting the registration deviation even when it is determined that the sensor is dirty in the first registration correction control after the power is turned on will be described.

FIG. 9 shows a block diagram of an embodiment of the present invention. The registration sensor unit 300A includes a light emitting unit 300, a light receiving unit 301, and a composite plastic lens 302. Light (hereinafter abbreviated as light source light) Io emitted from the light emitting unit 300 is reflected on the surface of the intermediate transfer body 12, and reflected light Ir is measured by the light receiving unit 301. The reflected light measured by the light receiving unit 301 is monitored by the LED light amount control unit 304,
It is sent to the CPU 305. The CPU 305 uses the light source light Io
And the measured value of the reflected light Ir, the mechanical installation error of each photosensitive drum, the optical path length error of each laser beam, the optical path length change, etc. are calculated, and the image signal is subjected to mechanical correction and electrical correction, and the correction value is obtained. Is stored in the non-volatile memory 901.

If it is determined that the registration sensor is dirty at the registration correction control timing, the power is turned on by acquiring the correction value from the non-volatile memory 901 used when the registration correction control was previously performed and performing image formation. Even if the registration is not performed even once, the image quality can be guaranteed to some extent.

[0049]

As described above, according to the present invention, a slit is provided on the intermediate transfer member, and a reflection plate is provided on the extension of the registration sensor and the slit portion to detect the dirt of the registration sensor. Is possible.

Further, when the registration sensor is detected to be dirty, the user is prompted to clean the registration sensor, and the registration correction control is postponed until the registration sensor is cleaned. It is possible to avoid applying appropriate mechanical and electrical corrections.

Further, when the registration correction control is normally completed, the calculated correction value is stored in the non-volatile memory, and when it is determined that the registration sensor is dirty, the previous registration sensor correction control is performed. By taking out the calculated correction value from the non-volatile memory and forming an image on the basis of the correction value, the image can be guaranteed to some extent.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a laser printer as a color image forming apparatus.

FIG. 2 is a schematic diagram of an intermediate transfer member.

FIG. 3 is a block diagram of a registration sensor.

FIG. 4 is a flowchart of registration correction control.

FIG. 5 is a block diagram of a registration sensor (No. 2)

FIG. 6A is a schematic view of an intermediate transfer member (2).

FIG. 6-2 is a schematic view of an intermediate transfer member (3).

FIG. 6-3 is a schematic view of an intermediate transfer member (4).

FIG. 7: Correlation diagram between registration sensor dirt and sensor output

FIG. 8 is a flow chart of registration sensor stain detection.

FIG. 9 is a block diagram of a registration sensor.

[Explanation of symbols]

1 cassette 3 Manual feed unit 4 transfer body 6 Registration sensor 18 Drive roller 19 Sensor before cash register 20 Fixing paper ejection sensor

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 21/00 510 G03G 21/00 510 F term (reference) 2H027 DA09 DE02 DE07 DE10 EA18 EB04 EC03 EC06 EC20 EE02 GB07 HA02 HA10 HA13 HA14 HB05 HB09 2H200 FA02 FA08 FA12 GA12 GA23 GA34 GA47 GB25 GB33 HA03 HB12 JA02 JB13 JC04 JC10 JC12 JC20 LB13 PB12 PB15 PB17 PB22 PB39 2H300 EA02 EK16 EC02 EC01 EC02 EC15 EC02 EC15 EC01 EC02 EC15 EC01 EC02 EC15 EC01 EC02 EC15 EC01 EC01 EC01 EC02 EC15 EC01 EC02 EC15 EC01 EC02 EC15 EC01 EC02 EC15 EC02 EC15 EC01 EC02 EC15 EC01 EC02 EC15 EC02 EC15 EC01 EC02 EC15 EC01 EC02 EC15 EC01 EC02 EC15 EC01 GG37 QQ10 QQ35 RR13 RR19 RR23 RR26 RR38 RR50 TT03

Claims (3)

[Claims] 1. A latent image forming means for forming a latent image by scanning a photoreceptor with an optical scanning system by a modulated laser beam, and a latent image formed on the photoreceptor is visualized by a developer. In an image forming apparatus in which image forming stations having developing means arranged in parallel for developing colors are provided, an intermediate transfer member for transferring the developer image formed at each image forming station is provided, and a predetermined image transferred on the intermediate transfer member is provided. A detection means for detecting the image of the image, a correction means for correcting the registration of each image forming station based on the detection result of the detection means, a slit on the surface of the intermediate transfer member, and a reflection plate inside the intermediate transfer member. A registration sensor unit including a light emitting unit that irradiates the surface of the intermediate transfer member with light and a light receiving unit that receives the light reflected by the intermediate transfer member. An image forming apparatus comprising: a registration sensor stain detection unit that detects that the registration sensor is soiled based on the output of the satellite unit. 2. When the registration sensor stain detection unit determines that the registration sensor is dirty, the registration sensor stain detection unit includes a reporting unit that reports to the user that the registration sensor is soiled. The image forming apparatus according to item 1. 3. A means for storing the correction value calculated by the correcting means for correcting the registration of each image forming station in a non-volatile memory, and the registration sensor dirt detecting means dirty the registration sensor. The image forming apparatus according to claim 1, further comprising: a unit that acquires a correction value from the non-volatile memory and forms an image when the determination is made.