JP2000275555A - Position adjusting method for optical scanner of image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely detect the position shift of a formed image without forming a toner image as a pattern image for adjustment by providing an area sensor which detects positions optically scanned with irradiating lights from respective optical scanners. SOLUTION: A position detecting device 40a has area sensors 41a-1 to 41a-3 arranged in a scanning direction corresponding to the positions irradiated with the laser lights. Position detecting devices 40b to 40d are also constituted similarly. The position detecting devices 40a to 40d have their respective area sensors 41a to 41d provided in the relation of the positions corresponding to irradiation positions on the photoreceptor of an image formation station. The body formed by integrating the position detecting devices 40a to 40d is inserted into the main body of the image forming device. The position detecting devices 40a to 40d are arranged opposite corresponding to optical scanners 28a to 28d. The optical scanners 28a to 28d are driven to perform irradiation with the laser lights. The respective area sensors 41a to 41d detect photodetection states of the scans with the laser lights and output signals indicating the scanning positions.

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 capable of reproducing and outputting input image data as a visible image and providing a plurality of optical scanning devices for scanning optical information corresponding to the image data. The present invention relates to a position adjustment of an optical scanning device capable of stably maintaining a clear image quality by appropriately adjusting a positional relationship of the optical scanning device.

[0002]

2. Description of the Related Art Conventionally, an image of a document or the like is read, and the read data is used as an input image, and the image is reproduced and output by using a printer for reproducing the image, for example, a laser printer. As this printer, that is, an image forming apparatus, an apparatus employing an electrophotographic method is widely used.

In a printer using this electrophotographic method, for example, a photosensitive member, which is a drum-shaped (or belt-shaped) image carrier, is uniformly charged, and a laser beam modulated on the surface thereof in accordance with image data. , An electrostatic latent image corresponding to the image data is formed. This electrostatic latent image is not visible, is developed with a colorant such as toner to make it visible, and the developed image (toner image) is transferred to a sheet-like transfer material and fixed. It is configured to perform discharge processing to the outside of the device via the device.

Therefore, it is necessary to maintain a constant positional relationship between the above-described scanning optical system for scanning the above-mentioned optical information and the photosensitive member. Therefore, the scanning optical system is unitized to maintain the positional relationship with the photosensitive member. An adjusting mechanism for adjusting is provided.

On the other hand, in order to form a color image, conventionally, a photoreceptor is irradiated with light of each color obtained by color separation, and the formed electrostatic latent image is developed with toner of each color corresponding to the irradiated light. Is transferred to a sheet or the like, and a toner image of a color formed according to each color separation light is sequentially transferred to form a color image. In this case, if the toner of each color to be transferred onto the sheet is superimposed, that is, if the alignment is not performed accurately, color shift, blur, reproduction with different colors, etc. may occur, and clear and faithful colors will be reproduced. Can not.

In order to increase the speed of forming a color image, the above-described scanning optical system, photosensitive member, developing device and the like are formed as one process means (image forming station), for example, for each of yellow, magenta, cyan and black. There is a system in which the process units are arranged side by side and the transfer position of each process unit is set so that the sheet is conveyed, so that the toner images are sequentially superimposed and transferred. According to this method, the sheet is conveyed only in one direction, and the toner images of the respective colors are sequentially transferred, so that the conveying system is simplified and the color image forming speed can be further increased.

On the other hand, if the transfer position of the sheet passing through the above-described process means for each color is shifted, a clear image cannot be formed as described above. In order to adjust the deviation, for example, there is one disclosed in Japanese Patent No. 2765626. This is because a conveyance belt that adsorbs and conveys the sheet is provided so that the sheet passes through the transfer position opposite to the photoconductor of the process means of each color, and the position of the conveyance belt is measured on the photoconductor of each color. The transfer pattern image is transferred to the conveyor belt, the position where the transferred image is formed is detected by an arranged sensor, and the shift amount is measured. The image forming timing of each color is adjusted and controlled in accordance with the measured shift amount so that the above-described measurement pattern images can be formed on the transport belt at predetermined intervals. This prevents a shift of each color image transferred to the conveyed sheet, thereby forming a clear and faithful color image.

[0008]

By adjusting the shift of the process means for each color as described above, the shift of the transfer position of the toner image of each color transferred onto the sheet can be eliminated. However, according to the conventional adjusting mechanism, in order to detect the deviation of the toner image formed by the process means of each color in the sheet conveying direction, an adjusting pattern image is formed on the conveying belt many times, and this is detected. I am trying to do it. As a result, wasteful consumption of toner is caused, and the inside of the image forming apparatus is stained with toner before shipping, and it takes time to remove the toner after adjustment. In addition, there is a risk that the process means may be mechanically displaced when the toner is cleaned and removed.

Further, the sensor for detecting the formed adjustment pattern image needs to detect the toner of each color by itself, and there is a concern that a detection error may occur due to a difference in color. Therefore, even if signal processing for eliminating an output change due to a difference in color is performed and output as a pattern detection signal is considered, it is easily affected by noise and the like, and there is a limit in accuracy.

Further, the pattern image for measurement is formed on one edge of the conveyor belt. Therefore, it is possible to detect the positional deviation in the sheet conveying direction.
That is, it is not possible to detect a shift in the main scanning direction by the scanning optical system in the width direction of the sheet, a tilt of a scanning line by the optical scanning device, and the like. Therefore, in order to perform the detection, it is necessary to provide separate detection means and adjust the inclination and the like. For this reason, it is difficult to detect the respective shift amounts with a single detection sensor and to adjust them.

According to the present invention, particularly, in an image forming apparatus capable of forming a color image, it is possible to accurately correct a shift of an image formed by a plurality of image forming process means without forming a toner image as a pattern image for adjustment. It is an object of the present invention to provide an adjustment method of an optical scanning device that enables detection of a displacement or the like and enables each adjustment based on the detection.

It is another object of the present invention to detect not only a shift in a sheet conveying direction but also a shift in a scanning direction by an optical scanning device and to recognize a shift in a conveying direction and a direction orthogonal thereto. The purpose of the present invention is to enable adjustment control.

[0013]

According to the first aspect of the present invention, there is provided a method for adjusting a position of an optical scanning device in an image forming apparatus, the method comprising: In an image forming apparatus in which a plurality of optical scanning devices for scanning light in the direction of a rotation axis are arranged in a fixed relationship, an image carrier to which light from each of the optical scanning devices is irradiated is provided. A position detection device including an area sensor that is arranged in place of a position and detects a scanning position to be optically scanned, and based on a position detection signal from the position detection device, a shift amount between the optical scanning devices and a scanning line. The method is characterized in that the shift amount in the direction is recognized, and adjustment is performed based on the recognition result so as to eliminate the shift amount, so that the shift between the respective optical scanning devices and the shift between the respective optical scanning lines are eliminated.

According to such a configuration, by arranging the position detecting device having the area sensor capable of detecting the optical scanning position of the optical scanning device at the position of the image carrier of the image forming apparatus, the light scanning position can be adjusted. Is detected. The difference between the scanning positions of the respective optical scanning devices can be recognized as a shift amount. for that reason,
Adjustment of the scanning start timing and the like is performed in accordance with the deviation between the optical scanning positions. For example, the deviation in the sheet conveyance direction is eliminated, and the adjustment can be easily performed so that the leading lines of the images coincide. Further, the shift amount due to the optical scanning line can be recognized as the inclination of the scanning line, whereby the inclination of each optical scanning line can be matched. The inclination of the scanning line is naturally adjusted so as to coincide with the rotation axis of the image carrier. Therefore, in image formation by a single area sensor, the amount of shift for performing each adjustment for matching images can be easily recognized. In addition, it is not necessary to form a toner image using an adjustment pattern, and an image carrier or the like may be mounted after the adjustment, which eliminates the trouble of removing and cleaning the toner and the occurrence of a displacement at that time.

In the method of adjusting the position of the optical scanning device in the image forming apparatus having the above-mentioned configuration, according to the invention described in claim 2, the position detecting device keeps the positional relationship of each area sensor constant. It is integrated, and at the time of position adjustment, by mounting the integrated position detection device instead of the image carrier of the image forming apparatus main body, the position detection indicating the positional relationship of each optical scanning device is performed, It is characterized in that the position is adjusted based on the displacement amount in the position detection result. Therefore, the positional relationship between the area sensors of the position detecting device can be stably secured, and accurate detection can be performed. Further, since the image carrier and the like are conventionally provided in the image forming apparatus in a detachable manner, the position adjusting device can be easily mounted at a predetermined position using the image carrier.
After completing the position adjustment, take out the position adjustment device,
An image carrier or the like may be mounted.

According to a third aspect of the present invention, in the method for adjusting the position of the optical scanning device in the image forming apparatus, the area sensor of the position detecting device includes at least writing by the optical scanning device. It is characterized in that the write start position at the start timing can be detected, the amount of deviation due to the difference between the write start position signals detected by each area sensor is recognized, and adjustment is made so that they are at the same position. In this manner, the shift amount of the write start position can be easily recognized, and the write start position can be matched in all the optical scanning devices based on the shift amount. It can be easily resolved.

In the method for adjusting the position of the optical scanning device in the image forming apparatus having the above-mentioned configuration, according to the invention described in claim 4, the area sensor of the position detecting device is configured to end writing by the optical scanning device. The end position at the timing can be detected, and the difference between the position detection and the position detection from the area sensor for detecting the writing start position is recognized as a shift amount of the magnification in the optical scanning direction. The present invention is characterized in that the scan driving clock frequency is adjusted and controlled. By matching the start positions of the scan lines and eliminating the shift of the end positions of the scan lines, the widths of the scan lines can be matched in all cases.

Further, in the method of adjusting the position of the optical scanning device in the image forming apparatus having the above-described configuration, according to the invention described in claim 5, the light is adjusted with reference to one of the plurality of optical scanning devices. After adjusting the inclination of the optical scanning line by the scanning device, the optical scanning lines of the other optical scanning devices are adjusted so as to match, and thereafter, the deviation amount between the optical scanning devices is adjusted. Features. The inclination of the scanning line is adjusted with reference to one of the optical scanning devices so that the scanning line is parallel to the reference line. The reference line is, for example, a line parallel to the rotation axis of the image carrier. Therefore, by first adjusting the scanning line of one optical scanning device to the reference line and adjusting the other optical scanning device based on the reference line, the procedure can be simplified and the deviation amount can be easily adjusted. .

According to a sixth aspect of the present invention, there is provided a method for adjusting the position of an optical scanning device in an image forming apparatus having the above-described configuration, wherein each optical scanning is performed by detecting a position of each area sensor by the position detecting device. The apparatus is characterized in that the respective shift amounts of the apparatus are displayed, and the adjustment can be performed according to the display. With this display, the deviation amount can be easily recognized, and appropriate adjustment can be performed based on the deviation amount. Further, the shift amount is input, and automatic adjustment control for eliminating the position shift of each formed image based on the shift amount can be enabled.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image output apparatus according to the present invention will be described below with reference to the drawings.

FIG. 1 shows the positional relationship between each optical scanning device held in a fixed relationship for explaining the first embodiment of the present invention and a position detecting device for performing position adjustment according to the present invention. FIG. 3 is a perspective view illustrating a relationship for detecting a timing of starting image formation by the optical scanning device, a tilt of the optical scanning device, and the like. FIG. 2 is a perspective view showing a configuration in which a position detecting device for detecting a shift or the like of optical scanning by the optical scanning device according to the present invention is integrated with the main body of the image forming apparatus, and is attached to and detached from the main body of the image forming apparatus. is there.
FIG. 3 is a configuration diagram illustrating an example of an image forming apparatus including the optical scanning device illustrated in FIG. 1, that is, a color image forming apparatus.

First, the general configuration of the image forming apparatus according to the present invention will be described with reference to FIG.

The image forming apparatus shown in FIG. 3 shows the structure of a digital color copying machine. The present invention is not limited to such a digital copying machine, but inputs image data from the outside and reproduces and outputs the image. The present invention can be directly applied to a color image forming apparatus such as a printer.

Therefore, a transparent platen 2 on which a document is placed and an operation panel to be described later are provided on the upper part of the main body of the digital copying machine 1 shown in FIG. Supported in an openable and closable manner with respect to the platen 2;
An automatic document feeder (ADF) 3 is mounted on the document table 2 with a predetermined positional relationship. Inside the main body of the digital copying machine 1, there are provided a reading device 4 for reading an image of a document placed on the document table 2, and an image forming section 10 below the reading device 4.

The automatic document feeder 3 feeds the documents placed on the placing table 3a one by one to the document table 2, and when the reading by the reading device 4 is completed, the document is discharged to the discharge tray 3b and the next time. The conveyance of the document is started, and the document is automatically sent to the document table 2. In the case of a document having images formed on both sides, the automatic document feeder 3 first conveys one side to the document table 2 and discharges the document when reading of that side is completed. Without reversing the front and back sides, the document is sent to the document table 2 again, and after reading the image on the opposite side of the document, the document is discharged and one side of the next document is fed to the document table 2. ing.

A reading device 4 for reading an image of a document sent to the document table 2 by the automatic document feeder 3 comprises:
A first scanning unit 5 and a second scanning unit 6 that are reciprocated in parallel with the document table 2 are provided. First
The scanning unit 5 supports an exposure lamp that illuminates the original, a mirror that reflects light reflected from the original to a target position, and the like. Further, the second scanning unit 6 includes a pair of reflecting mirrors for reflecting the reflected light image reflected by the above-mentioned mirror to the CCD 8 which is a reading element via the imaging lens 7 constituting the reading device 4. Supported.

The first scanning unit 5 runs at a predetermined scanning speed from a home position (left side in FIG. 3) when reading an image of a document. Then, the second scanning unit 6 travels in the same direction at half the scanning speed. As a result, the image of the document is sequentially formed on the CCD 8 via the image forming lens 7, and the CCD 8 outputs read data that has been photoelectrically converted. The CCD 8 is provided with R, G, and B CCDs for color-separating the image if the original is color, or a color separation filter or the like is arranged in the optical path to read the color-separated image. Output data. CC
The read data output from D8 is converted into image data by the image forming unit 1 through a processing circuit that performs image processing for forming a color image or the like in the image forming unit 10 as described later.
Transferred to 0.

The image forming section 10 for reproducing the image data obtained through the reading device 4 as a visible image on a sheet has a paper feeding device 11 at a lower portion. The sheet feeding device 11 is provided with a sheet feeding unit that stores the sheets S in a sheet feeding cassette or a tray and separates and feeds the sheets one by one. The sheet sent out by the sheet feeding device 11 includes a registration roller 1 disposed in front of an image forming position.
It is sent to 2. The registration roller 12 is a well-known one, and is configured to convey a sheet to an image forming position in a timely manner.

An image forming unit 10 is provided above the sheet feeding device 11.
A transport belt mechanism 14 for movably holding a transfer belt 13 as a sheet holding member constituting the image forming apparatus is provided. The transport belt mechanism 14 includes a drive roller 15 that stretches the transfer transport belt 13 formed in an endless shape, and a driven roller 16. The transfer transport belt 13 is configured to transport the sheet P by electrostatically attracting the sheet P. Therefore, the driven roller 16 is moved to the registration roller 12 side.
The charging roller 17 is disposed so as to be in contact with the driven roller 16 and is pressed against the driven roller 16 via the transfer / conveying belt 13.

Further, a fixing device 18 for transferring a toner image transferred onto the sheet S, which will be described later, to the sheet is disposed on the drive roller 15 side of the transport belt mechanism 14. As the sheet S passes between the fixing roller nips of the fixing device 18, the toner on the surface is melted and fused and fixed on the sheet surface. The sheet S is transferred to the fixing device 18.
Is fixed and transported in the transport direction switching gate 1
The paper is then discharged by a discharge roller 20 to a paper discharge tray 21 provided so as to protrude out of the main body of the copying machine 1.

The switching gate 19 selectively switches between discharging the fixed sheet to the discharge tray 21 as described above and re-supplying the sheet to the image forming position of the image forming section 10 again. The conveyance path of the sheet S is switched. If image formation on both sides of the sheet S is selected, the switching gate 19 is controlled so as to guide the sheet S to the switchback transport path 22. As a result, the sheet S is again conveyed to the registration roller 12 just before the image forming position in the image forming unit 10 after the sheet S is turned upside down via the switchback conveyance path 22.

On the other hand, the image forming section 10 is arranged above the above-mentioned transport belt mechanism 14, in particular, on the linear portion (horizontal portion) of the transfer transport belt 13, in the order from the upstream in the transport direction in the vicinity of the transfer transport belt 13. The first, second, third and fourth image forming stations (process means) Pa, Pb, Pc and Pd are arranged side by side. The transfer conveyance belt 13 is stretched between the driving roller 15 and the driven roller 16 as described above, and is driven to run in the arrow Z direction by the rotation of the driving roller 16. Then, the sheet conveyed via the registration roller 12 is held so as to be electrostatically attracted to the transfer conveyance belt 13 by the action of the charging roller 17. The sheet S is transferred to the image forming stations Pa, Pb, Pc, P
d.

Each image forming station Pa, Pb, P
c and Pd have substantially the same configuration, and are a photosensitive member 23 which is a drum-shaped image carrier that is driven to rotate in the direction of arrow F in the figure.
a, 23b, 23c, and 23d. Chargers 24a, 24b, 24 for uniformly charging the photosensitive members are provided around the respective photosensitive members 23a, 23b, 23c, 23d.
c and 24d, and a developing device 25a according to the present invention for visualizing the electrostatic latent image formed on the photoconductor with toner of each color.
Transfer means 25b, 25c, 25d and a transfer means 2 for transferring the developed toner image to a sheet, which are provided in contact with the back surface of the transfer / transport belt 13 to constitute the transfer device of the present invention.
6a, 26b, 26c, 26d, and a cleaning device 27a, which removes toner remaining on the photoreceptor surface after transfer.
27b, 27c and 27d are sequentially arranged along the rotation direction of the photoconductor.

Each of the photoconductors 23a, 23b, 23c,
A semiconductor laser device that emits dot light (information light) modulated according to image data according to the present invention, a deflecting device that deflects light from the semiconductor laser device in the main scanning direction, and a deflection device that deflects the light from the semiconductor laser device in the upper portion of 23d. Optical scanning devices 28a, 28b, 28b, which irradiate a laser beam which constitutes a scanning optical system (optical scanning device) including an f-θ lens and the like for forming (exposing) the laser beam on the photoreceptor surface. 28c,
28d are provided for each. The above-mentioned deflecting device is generally a polygon mirror which is a rotating polygon mirror.
Mirror motors 31a to 31d for rotating the polygon mirror at a predetermined speed at a high speed.
Is incorporated.

The optical scanning device 28a receives image data corresponding to a color component image of a color original image corresponding to the color of the mounted developing device 25a. For example, the developing device 2
When the toner 5a contains the toner corresponding to yellow (Y), the optical scanning device 28a receives the R input from the reading device 4 into the image processing device (not shown) as described above.
Data conversion for reproducing yellow is performed from the color image data of (red), G (green), and B (blue), the converted yellow image data is input, and image exposure is performed by the input. Become.

The optical scanning device 28b is provided with a developing device 25.
Image data corresponding to the color component image of the color original image corresponding to the color b is input. When the developing device 25b contains magenta (M) toner, the light scanning device 28b
Is subjected to data conversion in order to reproduce magenta from the R, G, B components of the input color image data, the magenta image data is input, and image exposure is performed.

Further, the optical scanning device 28c includes the developing device 25
Image data corresponding to the color component image of the color original image corresponding to the color c is input. When the developing device 25c contains cyan (C) toner, the optical scanning device 28c converts the R, G, and B components of the input color image data into data for reproducing cyan, and converts the data to cyan. Cyan image data is input, and image exposure is performed accordingly.

Then, the leftmost optical scanning device 28d in FIG.
Inputs image data corresponding to a color component image of a color original image corresponding to the color of the developing device 25d. When the developing device 25d contains black (BK) toner, black image data converted corresponding to black is input to the optical scanning device 28d, thereby performing image exposure. In particular, with respect to the black image data, the components of the input R, G, and B are substantially the same, and are input to the laser irradiation device 28d in order to perform the development using black.

As a result, an electrostatic latent image corresponding to the color of the color-converted original is formed on the photoconductors 23a, 23b, 23c and 23d of each image forming station. And
Each of the image forming stations Pa, Pb, Pc, and Pd is developed with the toner of each color by the developing devices 25a, 25b, 25c, and 25d, and is reproduced as a toner image corresponding to the color image of the document.

The first image forming station Pa
And a registration roller 12 for adsorbing the sheet to the transfer belt 13 as described above.
7, the sheet S sent through the registration roller 12 is reliably electrostatically attracted to the transfer / conveyance belt 13, and in this state, the conveyance belt mechanism 14 is used.
, The paper is sequentially conveyed to the first to fourth image forming stations Pa, Pb, Pc, and Pd without shifting. Therefore, the sheet S is formed by the photoconductors 23 formed at the image forming stations Pa, Pb, Pc, and Pd.
The toner images of the respective colors on a, 23b, 23c, and 23d are transferred so as to be sequentially superimposed, and a color image is reproduced.

Then, the fourth image forming station Pd
Between the fixing device 18 and the fixing device 18, a neutralizer 29 is provided almost directly above the drive roller 15 of the transport belt mechanism 14. Therefore, the sheet S that has passed through the fourth image forming station Pd has three colors of yellow, magenta, and cyan.
The toner images of four colors including color or black are superposed and transferred, and the electrostatic attraction state with the transfer belt 13 is released by the operation of the charge eliminator 29. 13 and sent to the fixing device 18. The static eliminator 29 is supplied with an AC voltage and performs an AC corona discharge to remove the charged charges.

In the color digital copying machine 1 having the above-described configuration, in order to form an image on a sheet, the sheet S is accommodated in a sheet feeding cassette or tray constituting the sheet feeding mechanism 11, and the cassette S Are sent one by one. The fed sheet S is fed via a transport roller or the like provided in a transport path to the registration roller 12 in order to feed the toner image to each transfer position of the toner image in each of the image forming stations Pa, Pb, Pc, and Pd. . The leading edge of the fed sheet P is detected by a sensor (not shown) or the like, and is temporarily stopped at the position of the registration roller 12 by a signal output from the sensor. Then, at a timing with each of the image forming stations Pa, Pb, Pc, and Pd, the sheet is fed to the transfer / conveying belt 13 rotating in the arrow Z direction shown in FIG.

At this time, the transfer / conveying belt 13 is given a predetermined charge by the action of the charging roller 17, and the sheet S is electrostatically attracted to the transfer belt 13. Thereby, while passing through the image forming stations Pa, Pb, Pc, and Pd, stable conveyance is performed in a sucked state,
The toner images of each color formed in each station are sequentially transferred and superimposed.

That is, each image forming station Pa, P
b, Pc, and Pd, the toner image of each color is
3a, 23b, 23c, and 23d, which are sequentially superimposed and transferred onto the surface of the conveyed sheet P electrostatically attracted by the transfer / conveyance belt 13. Then, finally, the fourth image forming station Pd
When the transfer of the toner image is completed, the sheet S is separated from the transfer and conveyance belt 13 by the action of the charge remover 29 from the leading end of the sheet S. Then, the peeled sheet S is guided to the fixing device 18, and the color toner image superimposed and transferred on the sheet S is melted and fixed, and is output to the paper discharge tray 21.

(First Embodiment of the Present Invention) In the color digital copying machine 1 as shown in FIG. 3, the read data read by the reading device 4 as described above is transferred to the image forming stations Pa, An image processing circuit (not shown) is provided to reproduce Pb, Pc, and Pd as a toner image. Normally, the read data from the reading device 4 is R
(Red), G (green), and B (blue) color-separated read data that can be processed by the image forming unit 10 is Y
(Yellow), M (magenta), C (cyan), BK
(Black) color image data. Therefore, in order to perform the color conversion processing and the like, the digital copying machine 1 is provided with a well-known image processing circuit (not shown).

As described above, in the image processing circuit, each of the image forming stations Pa, Pb, Pc, P
d, and the processed image data is sent to each of the target optical scanning devices 28a to 28d as the above-described Y, M, C, and BK color image data for each color.

Therefore, the optical scanning device 2 according to the present invention
A polygon mirror 30 of 8a to 28d (hereinafter, one laser irradiation device is described as 28) has its center of rotation directly connected to the rotation axis of a mirror motor 31 rotated at a predetermined speed, and is modulated according to image data. In particular, the surface of the photoreceptor 23 is deflected in the direction of the rotation axis and scanned by using a laser beam from a semiconductor laser which is driven ON-OFF as information light. In particular, the semiconductor laser is driven ON-OFF according to image data based on a preset basic clock signal. Then, the frequency of the clock signal, the driving voltage, and the like are output from a voltage controlled oscillator (VCO) and driven based on the output.

The optical scanning device 28 according to the present invention has the same structure in all cases and is unitized. In the unit, a semiconductor laser and the polygon mirror 3 described above are provided.
0, a mirror motor 31 for rotating the mirror, an f-θ lens 32 for imaging the laser beam deflected by the polygon mirror on the surface of the photoreceptor 23, and mirrors 33, 3
4 and the like are provided as respective units a to d. These polygon mirrors 30 and the like are incorporated in the same support, are unitized, and are respectively positioned and supported by a support 37 having a housing configuration as shown in FIG. 4, for example, and constitute an optical scanning device 28.

In the optical scanning device 28, a positioning shaft 36 is attached to the support 37 in parallel with the scanning lines in order to adjust the scanning lines for scanning the respective optical information so as to be aligned in parallel. . One end of the shaft 36 is attached to the support 37, and the other end is provided so as to be able to adjust the position thereof so as to pass through a long hole 37 a formed on one frame 37-1 side of the support 37. .

As shown in FIG. 4, the support member 37 includes front and rear frames 37-1 for mounting and supporting the shaft 36.
37-2 and side frames 37-3 and 37-4 for providing a housing configuration with a predetermined distance between the front and rear frames 37-1 and 37-2. Slot 3 above
7 a is formed on the front frame 37-1 of the support 37.

On the front and rear frames 37-1 side of the support 37, corresponding to the respective optical scanning devices 28a to 28d,
An adjusting member 38 is provided corresponding to the elongated hole 37a. The adjusting member 38 is fixed to the outside of the front frame 37-1 of the support housing 37, including the elongated hole 37a.
It comprises an angle 38-1 having a U-shape, and an adjusting screw 38-2 having one end provided on a shaft 36 which is screwed to the angle 38-1 and penetrates a long hole. This makes it possible to adjust the inclination (inclination) of the optical scanning device 28 in the scanning line direction or the like within the range of the elongated hole 37a with the adjustment screw 38-2, and all the optical scanning devices 28a to 28d. Can be adjusted so that the scanning lines are parallel.

Therefore, as described above, the optical scanning device 28a
A position detecting device according to the present invention, which detects inclinations in the scanning line direction of .about.28d and misregistration between the optical scanning devices 28a to 28d, will be described below with reference to FIG.

In FIG. 1, each of the optical scanning devices 28a-28
Position detection devices 40a to 40d that can detect the scanning position by the laser beam are provided in correspondence with the positions d. These position detecting devices 40a to 40d
Is configured by integrating individual units or by integrating them. The position detection device 40a is an area sensor (plane sensor) corresponding to the position where the laser beam is irradiated.
41a-1, 41a-2, and 41a-3 are arranged corresponding to both ends and the center in the scanning direction.

The position detectors 40b, 40c, 40
d is the area sensors 41b-1 to 41b, respectively.
b-3, 41c-1 to 41d-3, 41d-1 to 41d
-3 is provided. In particular, the position detection devices 40a-4
Reference numeral 0d indicates that the area sensors 41 are provided in a positional relationship corresponding to the irradiation positions of the image forming stations Pa to Pd on the photoconductors 23a to 23d. Therefore, the laser beams from the light irradiation devices 28a to 28d are imaged on the light receiving surfaces of the area sensors 41 described above.

The area sensor 41 detects the scanning position by receiving the laser beam, and outputs a signal indicating the scanning position. The area sensor 41 is configured by, for example, an area sensor such as a CCD. Further, it may be configured by providing a photodiode in a planar shape.

The position detecting devices 40a to 40d are accurately integrated in a positional relationship corresponding to the optical scanning devices 28a to 28d, and the integrated object is mounted on the main body of the image forming apparatus. For this reason, as shown in FIG.
The front door 39 is opened so that the support 42 can be pulled out. Usually, the image forming stations Pa to Pd described with reference to FIG.

The image forming stations Pa to Pd are configured such that, for example, a process unit in which the photosensitive member 23, the charger 24, and the cleaning device 27 are integrated, and a developing unit including the developing device 25 can be individually attached and detached. It is configured to be detachably supported by the pull-out support 42 described above. Such a configuration can be achieved by a known configuration and is not a unique configuration according to the present invention.

Therefore, according to the present invention, the above-described process unit and developing unit of each color including the photoreceptor are removed from the support 42 in order to adjust the position between the optical scanning devices 28a to 28d and to adjust other deviations. The supporter 42 is mounted with the position detecting devices 40a to 40d described with reference to FIG. Then, by inserting the support 42 into the main body of the image forming apparatus 1, the optical scanning devices 28 a to 28
The position detection devices 40a to 40d are arranged to face each other corresponding to the position d.

The intervals between the area sensors 41a to 41d of the position detection devices 40a to 40d (the intervals in the direction in which they are arranged in FIG. 1, for example) are set to predetermined intervals. Also, the area sensors 41a-1 to 41a-3, 41b of the position detection devices 40a to 40d, respectively.
-1 to 41b-3, 41c-1 to 41c-3, and 41
The positional relationship between d-1 to 41d-3 in the scanning line direction is kept constant. In particular, the area sensor 41a
41a-3 are provided in parallel with the reference scanning line. The reference scanning line is parallel to, for example, the rotation axis direction of the photoconductor 23. The same applies to the other area sensors 41b, 41c, 41d.

Therefore, when there is no shift in the light irradiation position by the light scanning devices 28a to 28d, the same position of the area sensors 41a to 41d is irradiated with laser light, and this is detected. .

(Position Detection and Adjustment Method of the Present Invention) Hereinafter, the detection of the position shift and the like and the adjustment control thereof according to the present invention will be described. Therefore, first, the optical scanning device 2
8a to 28d are driven to emit laser light. This driving is performed by scanning each area sensor 41a-41 by scanning one line.
“d” detects a light receiving state by scanning with a laser beam. In particular, in the area sensors 41a to 41d, the optical scanning device 28
In the scanning of the laser beams a to 28d, if all the lines match in the scanning line direction of the area sensor, it can be confirmed that there is no shift in the scanning line direction of the optical scanning devices 28a to 28d.

However, the area sensors 41a-1 to 41a
If a line in a direction perpendicular to the scanning line is detected instead of the same scanning line in -3, it can be determined that the scanning line is scanned in an inclined state. Therefore, in order to adjust the inclination of the scanning line, as described with reference to FIG. 4, the adjustment shaft 36a is finely adjusted in any direction by the adjustment screw 38-2 so that the inclination is parallel. I do.
This is because each of the position adjusting devices 40b, 40c, 40
The shift amount is detected in accordance with the output state of each area sensor of d, and the inclination can be adjusted based on the detection.

In this case, the laser beam irradiation by the optical scanning devices 28a to 28d scans the line, but the semiconductor laser is not driven on all the scanned lines, for example, the area sensors 41a-1 and 41a-2. , 41
It is also possible to drive to emit one point at a position corresponding to each of a-3. In order to achieve such a configuration, a time point at which the scanning of the laser beam is started as conventionally known is detected by providing a beam detecting means (BD sensor) (not shown), and a clock signal determined from the detection time point is detected. It is controlled to instruct the start of writing after counting, which is well known.

For this reason, the semiconductor laser is driven (turned on) once at the timing of the write start point after the predetermined count from the time when the BD sensor detects, and at the timing from the start of scanning to the end of scanning. The laser is similarly driven one point. When the detection is performed at the center of the scanning line, the semiconductor laser is similarly driven by one point at the center of the start and end.
Thereby, the area sensors 41a-1, 41a-2, 4
One point is irradiated with laser light corresponding to 1a-3.

For this adjustment, the optical scanning device 28a
In the driving of .about.28d, the driving is performed by selecting a driving voltage or the like that can be received by the area sensor 41 and output a signal thereof, without actually using the amount of light to be written on the photoconductor. In this adjustment driving, if the area sensor 41 itself has the same sensitivity as that of the photoconductor, the driving is naturally controlled by the same voltage or the like.

The detection of the displacement and the adjustment for the displacement according to the present invention will be described with reference to examples.

Referring to FIG. 5A, the irradiation point of the laser beam at the scanning start timing (indicated by a black circle)
Is detected at, for example, the center (reference cell O) of the area sensor 41a-1, it is determined that the timing of the start of scanning writing is normal. Then, the shift amount is 0, and the adjustment is not performed.

The area sensor 4 detects the irradiation point of the laser beam at the timing of the end of the scanning writing.
1a-3 detects a state where the center cell O is shifted in the main scanning direction and the sub scanning direction. Therefore, it is detected that a tilt in the laser scanning direction, that is, a shift of one dot has occurred. This is determined by the difference between the position detected by the area sensor 41a-1 at the start timing and the position detected by the area sensor 41a-3 at the end timing.

In the case where the position is similarly detected by the area sensor 41a-2 at the center part of the scanning, one point of laser light irradiation is performed. Then, by detecting the scanning position, it can be confirmed that a slight shift occurs in the main scanning direction and the sub-scanning direction due to a difference from the detection position of the area sensor 41a-1 at the start.

Therefore, when the shift as shown in FIG. 5A is detected, the tilt of the scanning line of the optical scanning device 28a and the magnification shift in the main scanning direction, particularly the shift of the frequency of the scanning clock can be detected. According to such a detection result, the inclination of the scanning line is reduced as described with reference to FIG.
a is adjusted by adjusting the adjusting screw 38-2 of the adjusting device 38 along the direction of inclination. Further, the frequency shift in the scanning direction described above is caused by the clock oscillator (the voltage-controlled oscillator V).
(CO) adjustment. The detection and adjustment of such a positional shift are performed in the same manner in each of the optical scanning devices 28b, 28c, and 28d.

Next, a description will be given with reference to FIG. This is a case where a timing deviation of the start of writing occurs. Therefore, the reference cell O by the area sensor 41b-1 is used.
Is detected as a start timing shift in the main scanning direction. This is the optical scanning device 28 according to FIG.
The shift amount is detected based on the difference between the detection position of the area sensor 41a-1 which has detected the timing of the start of the scanning writing by a and the position detection by the area sensor 41b-1.

According to FIG. 5B, the timing of the start of writing by scanning is delayed by, for example, one pixel (one dot).
By making the D sensor subtract from the determined count number of the clock from the point of detection of the laser beam, it is possible to adjust the writing start point faster. In FIG. 5B, there is no shift due to the position detection between the start and the end, and if the start timing is adjusted, the end timing is adjusted accordingly.

FIG. 5C shows, for example, the optical scanning device 28.
5A and 5B, the timing of the start and the end of the writing of the scanning are described in FIG.
This coincides with the write start timing of the optical scanning device 28a according to (a), and no inclination in the main scanning direction is detected.
However, this is a state in which a shift in the sub-scanning direction orthogonal to the scanning line direction has been detected. That is, the shift amount in the sub-scanning direction corresponding to two dots from the reference cell O is detected. The amount of displacement is determined by the area sensor 41 that has detected the write start timing of the optical scanning device 28a described above.
It is also the difference from the detection position of a-1.

When the shift amount in the sub-scanning direction is detected,
It is necessary to make an adjustment to correct the deviation. The adjustment is performed at the beginning of the scanning line by the optical scanning device 28c.
Since the image forming timing is shifted in the sheet conveying direction and the inclination is not adjusted, and the image forming timing is fast, the image forming start control is performed so that the start timing of the head is delayed by two dots. adjust. That is, the start of the first line of image formation by the optical scanning device 28c is
Adjustment control is performed so as to be later than the regular reference timing.

As described above, the optical scanning devices 28a to 28a-2
8c, the amount of deviation due to the difference is detected by detecting the scanning position at the start or end timing of each other, and by adjusting so as to eliminate this deviation, all the scanning lines are parallel and the The write start position and the end position can be matched. As a result, it is possible to eliminate a difference in magnification (difference in scanning width) of an image actually formed in the main scanning direction and a shift of an image head. Therefore, the formed images match in all cases, and it is possible to eliminate the deterioration in image quality due to the shift.

The detection of the displacement between the optical scanning devices 28a to 28d is performed, for example, by detecting the light receiving cells by the area sensors 41a-1 to 41c-1 as described with reference to FIGS. It can be detected by the difference in position. That is, the light receiving cell positions in the area sensors 41a-1 and 41b-1,
For example, if it is detected on the same line as the reference cell C (main scanning direction), it can be detected that there is no displacement between the optical scanning devices 28a and 28b. However, FIG.
If the area sensor 41c-1 is detected in a cell other than the same line as the reference cell O as described in the above, this appears as a positional deviation of the distance between the optical scanning devices 28b and 28c in the sub-scanning direction. Thus, as described above, it is possible to match the start timing of image formation by adjusting and controlling the start timing. Further, also in the optical scanning device 28d, the positional deviations from each other and the various types of deviations described above are detected, and the correction based thereon is, of course, performed.

Next, with reference to FIG. 5 (d), a description will be given of the curved state of the scanning line by the optical scanning device 28. FIG. This will be described using the optical scanning device 28d as an example.
This is because there is no shift between the writing start point and the writing end point in the scanning with the laser light. Therefore, the inclination of the scanning line by the optical scanning device 28d is not detected. However, since the laser beam is not detected in the cells on the same line where the start and end of writing are detected by the area sensor 41d-2 at the center, it is detected that the scanning line is curved.

Such a curve is considered to be a curve on a reflection surface by a polygon mirror constituting the optical scanning device 28d, a curve by another mirror, or the like. In such a case, since compatibility with other optical scanning devices 28 cannot be obtained, replacement is performed as unit replacement. Although not described, each optical scanning device 28 is provided detachably with respect to the shaft 26 for tilt adjustment. Therefore, in the replacement, if the curvature of the scanning line is detected, the optical scanning device 2
8 is removed and a new optical scanning device is mounted.

On the other hand, in the case shown in FIG. 5E, the write start and end points are detected in the same cell in the same scan line, so that the width of the scan line, that is, the magnification is normal. Has been detected as. But,
The detection position of the area sensor 41-2 at the center is shifted in the main scanning direction. When such detection is performed, adjustment is partially performed. For example, since a shift has occurred in the main scanning direction at the center from the start of writing, frequency correction should be performed at that portion, and correction should not be performed at the end point from the center.

FIGS. 5D and 5E can be detected by providing an area sensor 41-2 at the center, and such a curve or a partial displacement is detected before assembly. In the case where the adjustment is performed, it is not necessary to provide the area sensor 41-2 in the position detection device 40.

The optical scanning device 28 uses a rotating polygon mirror (polygon mirror), and it is also an important problem that the scanning lines on each surface coincide with each other. Therefore, when a six-surface mirror is used, the writing start position, the ending position, and the like on all surfaces are detected by cells at the same position on the same line in six scanning lines after one rotation or integer rotation. In such a case, there is no problem. However, if a shift is detected in the scanning line even on one surface, the optical scanning device 28 can be replaced with a new one.

In the case of a deviation within the error range in this detection, it is also possible to obtain an average for each scanning line and perform mutual position adjustment using this position average.

(Another Specific Example for Misregistration Detection and Adjustment) In FIG. 6, the image forming stations Pa to Pd are taken out of the digital copying machine 1 shown in FIG. Position detecting devices 40a to 40d
Attach. Then, the position detection devices 40a to 40d
The signals from the area sensors 41 a-1 to 41 d-3 are input to the adjustment control circuit 45 via the signal line 43. The adjustment control circuit 45 is connected to a keyboard 46 for inputting numerical values, an adjustment start instruction, and other adjustment data, and a display device 47 for displaying necessary information.

For example, detection signals from the area sensors 41a-1, 41a-2, and 41a-3 of the position detection device 40a serially output photoelectrically converted data from each cell of the top line as conventionally known. In this case, the signal can be input to the adjustment control circuit 45 using one signal line 43. Therefore, the other position detection devices 40b to 40b
If the detection signal from d is sent to the adjustment control circuit 45, it becomes possible with a minimum of one. However, since the processing becomes slow, each position detection device 40a is connected by four signal lines 43.
If a detection signal of ~ 40d is input, the processing time can be reduced.

The adjustment control circuit 45 controls the start of driving of the optical scanning devices 28a to 28d via another signal line (not shown). By this driving, the adjustment control circuit 45 inputs the detection signals from the above-described position detection devices 40a to 40d, calculates the input result, and displays the contents thereof on the display device 4.
7 is displayed. The keyboard 46 and the display device 4
Reference numeral 7 denotes an operation panel 48 of the copying machine 1 as shown in FIG.
The adjustment control circuit 45 can be replaced by a CPU for controlling the copying machine 1 without being provided as a separate component.
The PU can achieve the function of the adjustment control circuit 45.

An example of the adjustment procedure will be described below. First, the positional relationship of the first optical scanning device, for example, the optical scanning device 28a corresponding to yellow in FIG. It detects, recognizes the amount of deviation, and performs adjustment based on it.

For this purpose, a command for driving the optical scanning device 28a is output from the adjustment control circuit 45. This driving start instruction can be given via the keyboard 46 or the like. When the optical scanning device 28a is driven, the semiconductor laser is driven to start irradiating the laser beam, and the polygon mirror 30 determines the start of scanning writing.
The detection by the sensor is performed. From this detection point, the driving of the semiconductor laser is stopped, and the counting of the clock signal corresponding to the formation of one pixel is started. When the count reaches a predetermined reference count value, the semiconductor laser is turned on for a time corresponding to one clock, and irradiation for one dot (one point) is performed.

Then, at least at the timing of the end point in the scanning line, the semiconductor laser is similarly turned on corresponding to one clock, and one dot is irradiated. At this time, if necessary, the semiconductor laser may be similarly turned on in the central portion. By this driving, at least the area sensors 41a-1, 41a of the position detecting device 40a are
The position signal detected at a-3 is input to the adjustment control circuit 45. As shown in FIG. 5A, for example, as shown in FIG. 5A, the position detection signals of the area sensors 41a-1 and 41a-3 have not detected the shift amount at the writing start point, and the area sensors 41a-1 and 41a-3 have not been detected. The adjustment control circuit 45 calculates the shift amount in the sub-scanning direction, ie, the position detection signal to which the inclination is input. That is, the area sensor 41a-1
Then, the position signal of the area sensor 41a-3 is compared with the position signal of the end area sensor 41a-3, and the line shift in the sub-scanning direction, that is, the difference is calculated. The calculation result is displayed on the display device 47.

The inclination of the optical scanning device 28a is detected.
When the tilt amount is displayed, the operator or serviceman adjusts the tilt according to the display. This is as described with reference to FIG. 4. The adjustment direction may be adjusted according to the displayed content.
It is delicately performed at 2. With this adjustment, the scanning line can be made parallel to the reference scanning line, that is, parallel to the reference scanning line of the position detection device 40a.

In this case, as shown in FIG. 7A, if the area sensors 41a-1 and 41a-3 detect the same scanning line, it is determined that the optical scanning device 28a has no inclination. The deviation amount is displayed on the display device 47 as 0. With this display, the position adjustment by the operator or the serviceman is not performed.

On the other hand, at the same time as the above-described detection of the inclination, the amount of deviation in the main scanning direction between the area sensor 41a-1 and the end area sensor 41a-3 is compared with the start and end position detection signals. The difference is calculated as a shift amount. If there is no difference, it is not necessary to perform the correction with the shift amount being 0, but if the shift amount corresponding to, for example, two dots in the main scanning direction is calculated as shown in FIG. 47 is displayed. In accordance with this display, the content is input via the keyboard 46 or the like, and is stored in the storage unit of the CPU which is the control circuit of the main body of the digital copying machine 1.
According to the stored contents, the clock frequency and the like of the laser drive timing in the optical scanning device 28a are adjusted and controlled.
This is performed as a magnification correction for making the scanning line width shift in the main scanning direction, that is, the start and end points of writing coincide.

Here, the central area sensor 41a-2
When the control is performed so as to perform the position detection, the difference from the position detection signal at the center, for example, as shown in FIG. However, in the present invention, by irradiating at least two points, the inclination of the scanning line, the amount of deviation in the main scanning direction, and the like can be reliably detected, and the contents can be displayed and adjusted.

By performing the above adjustment, the inclination with respect to the reference line of the specific optical scanning device 28a can be adjusted, can be made parallel thereto, and the magnification can be corrected. The reference line is as described above, and the area sensors 41a-1 and 41a
a-3 is parallel to the same line of the reference cell C, which is set, for example, parallel to the rotation axis of the photoconductor 23.

Then, the inclination and magnification of the optical scanning device 28b corresponding to the magenta adjacent to the optical scanning device 28a are corrected, and the detection and adjustment of the positional deviation between the optical scanning devices 28a which have been adjusted earlier are performed. Therefore, the optical scanning device 2
8b, the drive control of the semiconductor laser is similarly performed, and the position detection signals of the area sensors 41b-1 and 41b-3 are input to the adjustment control circuit 45.

By inputting the position detection signal, the inclination of the optical scanning device 28b and the shift amount in the main scanning direction are detected, the shift amount is displayed, and adjustment according to the shift is performed in the same manner. With this adjustment, for example, the scanning lines of yellow and magenta become parallel to the reference line.

Then, as shown in FIGS. 7A and 7B, the detection positions A1 and B1 of the yellow and magenta area sensors 41a-1 and 41b-1 are compared, and the deviation amount in the main scanning direction is determined. And the shift amount in the sub-scanning direction are calculated by the adjustment control circuit 45. In this case, the detection position A of the area sensor 41a-1 of the optical scanning device 28a for yellow is used.
1, the area sensor 41b of magenta
The shift amount between the main scanning direction and the sub-scanning direction is calculated based on the difference from the first detection position B1. In this case, the timing of starting writing by magenta is shifted by one dot, which is also a difference for matching the timing of starting writing of yellow.

Therefore, in the actual example of FIG.
A shift by a dot occurs, and a shift by one line also occurs in the sub-scanning direction. For this reason, the content of the shift amount in the main scanning direction is displayed, and input is performed according to the display, so that the adjustment control is executed in the main body of the digital copying machine 1 according to the shift amount. This is as described above. The timing adjustment of the writing start of the optical scanning device 28b by magenta is performed by correcting the count number of the clock from the time when the laser beam is detected by the BD sensor to the start of the writing. This correction is performed according to the above-described input shift amount.

The adjustment of the shift amount in the sub-scanning direction is performed with respect to the yellow and magenta optical scanning devices 28a, 28a.
Since a deviation from the designed distance L1 between the exposure scanning lines in b is set, a predetermined time from the writing from the yellow scanning line to the writing of the cyan scanning line is set as a delay time, It is possible to adjust the amount of displacement between the two in the sub-scanning direction.

The amount of deviation in the main scanning line direction, that is, the inclination, is determined by the area sensor 4 as described above.
The difference is detected by the difference between the position detections 1b-1 and 41b-3 in the main scanning direction (position detections B1 and B3), the display is performed, and the adjustment is performed. Separately from this, the yellow area sensor 41a-3 and the magenta area sensor 41a
From the amount of deviation from b-3 in the main scanning direction (difference between position detections A3 and B3), the amount of deviation was calculated in order to adjust the timing of the start of the previous writing. As a shift amount (correction value) in the scanning direction, a clock frequency for driving the laser of the magenta optical scanning device 28c is adjusted by a voltage controlled oscillator (VCD). These correction values, that is, the amounts of deviation are displayed on the display device 47, input via the keyboard 46 or the like, and are automatically adjusted based on the input values.

In the same manner, similarly, the position of the laser beam for line scanning is similarly detected for each of the cyan and magenta optical scanning devices 28c and 28d, and their respective tilts are adjusted. Similarly, the shift amount in the main scanning direction and the sub-scanning direction can be detected as a reference, and the correction amount can be used as a correction value so that the laser writing start timing and the head scan line start timing can be adjusted and controlled.

In particular, the displacement in the sub-scanning direction is adjusted so that the distance L1 between the exposure lines of the optical scanning devices 28a and 28b matches the reference as shown in FIG. And
In accordance with this, the optical scanning device 28 is
The distance L2 between the exposure lines b and 28c and the distance L3 between the exposure lines between the optical scanning devices 28c and 28d are made to match the distance L1. Thus, the scanning lines of each color can be matched in the main scanning direction and the sub-scanning direction, and a good color image can be obtained without displacement in the main and sub-directions during transfer.

As described with reference to FIGS. 7 (a) and 7 (b), based on the yellow optical scanning device 28a, the positional deviation of each of the yellow optical scanning devices 28b to 28d is detected. Although the adjustment has been described based on the detected result, the present invention is not limited to this. For example, based on the black optical scanning device 28d, this and another optical scanning device 28a
28c may be detected, and adjustment may be performed based on this. In addition, it is needless to say that the same operation can be performed based on any one of the middle optical scanning devices 28b and 28c without using the optical scanning devices 28a or 28d disposed at both ends as a reference. is there.

Also, one is based on the optical scanning device 28d.
The other optical scanning devices 28c, 28b, and 28a are sequentially driven to perform the respective adjustments. However, they are simultaneously driven to start the area sensors 41a-1, 41b-1, and 41b-1 for the start detection.
Of the 41c-1 and 41d-1, the one detected in the reference cell O may be used as a reference, and the position shift amount with respect to the reference may be calculated. In this case, the reference optical scanning device is displayed on the display device 47 and the amount of deviation from the reference optical scanning device is displayed, and the adjustment can be similarly performed according to the displayed content.

In FIGS. 7A and 7B, in order to adjust the shift amount of the first scanning line in the sub-scanning direction, for example, the scanning of the optical scanning device 28b is started by the optical scanning device 28b. It has been described that the delay adjustment for one dot is performed for the adjustment. However, in FIG. 7A, the start of line scanning by the optical scanning device 28a with respect to the reference cell O is shifted by one dot with respect to the reference line (the line of the reference cell O). To adjust this, delay adjustment for one dot may be performed in the same manner. In this case, since the optical scanning device 28b is shifted by two dots from the reference line, the delay adjustment for two dots may be performed.

Such an adjustment is that, when a reference is determined, the amount of deviation from the reference may be obtained.
Either method may be selected. In particular, when the state shown in FIG. 7A is determined as a reference, a deviation from the sheet occurs. Therefore, the driving start timing of the registration roller 12 for adjusting the timing of starting the conveyance of the sheet may be adjusted.

[0106]

According to the image forming apparatus of the present invention, by scanning light corresponding to image data for image formation,
In an apparatus for forming a target image, an area sensor for detecting a position of optical scanning is provided in order to adjust a positional relationship between the optical scanning apparatus and the image forming medium. Can be easily detected as a shift amount, and adjustment based on the detection can be easily performed.

Therefore, without forming a toner image or the like for detecting the shift amount, adjustment according to the shift amount can be performed, wasteful toner consumption is eliminated, and the inside of the apparatus is contaminated with toner, and labor for cleaning it is reduced. Can also be omitted.

As for the amount of shift, the amount of shift in the main scanning and sub-scanning directions can be detected and the shift can be adjusted. Therefore, there is no need to provide another means for detecting the amount of shift, which is advantageous in terms of cost. .

Further, when the optical scanning devices are arranged side by side corresponding to each color, the adjustment for matching the inclination of the scanning line in each scanning device, the adjustment between the optical scanning devices, and the like can be performed in the same manner. There is no need to provide any means or detecting means.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state in which an optical scanning device for each color for explaining a first embodiment of the present invention and a position detecting device for detecting an optical scanning position by the optical scanning device are provided. is there.

FIG. 2 is a perspective view for explaining an embodiment in which the position detecting device according to the present invention shown in FIG. 1 is provided so as to be attachable to a digital copying machine main body.

FIG. 3 is a configuration diagram for explaining the entire internal configuration of the digital copying machine shown in FIG. 2;

FIG. 4 is a perspective view showing an example of enabling adjustment of the inclination of a scanning line of the optical scanning device according to the present invention.

FIG. 5 is an explanatory diagram for explaining a shift state and a shift amount by a scanning line by each optical scanning device according to the first embodiment of the present invention.

FIG. 6 is a diagram for explaining a control circuit configuration for detecting a shift amount by each optical scanning device according to the present invention.

FIG. 7 is a diagram showing an explanatory example for detecting a shift amount in FIG. 6;

FIG. 8 is an explanatory diagram for explaining a state of a positional deviation between optical scanning devices adjacent to each other and an adjustment thereof according to the present invention;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 digital copying machine (image forming apparatus) 4 reading apparatus (image input section) 10 image forming section 13 transfer / conveying belt 23 photoconductor 24 charger 25 developing device 26 transfer means 28 optical scanning device 30 polygon mirror (polyhedral mirror) 39 support Body 40 Position detection device 41 Area sensor 43 Signal line 45 Adjustment control circuit 46 Keyboard 47 Display device 48 Operation panel

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 21/14 G03G 21/00 372 2H076 9A001 (72) Inventor Shoichi Fukudome 22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka No. 22 Inside Sharp Corporation (72) Inventor Kyosuke Taka 22-22, Nagaike-cho, Abeno-ku, Osaka City, Osaka Prefecture Inside Sharp Corporation (72) Toshio Yamanaka 22-22 Nagaike-cho, Abeno-ku, Osaka City, Osaka Prefecture Within Sharp Corporation (72) Inventor Seo Manabe 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka F-term within Sharp Corporation (reference) 2C362 BA52 BA68 BA69 BA70 BA71 BA90 BB30 BB32 BB34 BB37 BB42 BB46 CA22 CA39 DA02 DA43 2G086 EE12 2H027 DA23 DA50 DE02 DE09 EA18 EB04 EB06 EC04 EC07 ED04 EF10 GA50 GB02 HA02 HA11 HB07 2H030 AA01 AB02 BB02 BB16 2H045 A A01 CA82 CA88 CA92 CA98 2H076 AB02 AB11 AB16 AB18 AB67 AB68 CA17 DA41 EA01 EA24 9A001 BB01 BB03 BB04 DD13 HH23 HH28 HH31 HH34 JJ35 KK16 KK29 KK31 KK37 KK42 LL09

Claims (6)

[Claims] 1. An image forming apparatus comprising: a plurality of optical scanning devices for scanning a rotating image carrier with light corresponding to image data in a rotation axis direction; A position detection device including an area sensor that is arranged in place of the image carrier irradiated with light from each of the optical scanning devices and detects a scanning position to be optically scanned; and a position detection from the position detection device. Based on the signal, the shift amount between the respective optical scanning devices and the shift amount of the scanning line are recognized. Based on the recognition result, the shift amount is adjusted so as to eliminate the shift amount. A position adjustment method for an optical scanning device in an image forming apparatus, wherein a shift of a scanning line is eliminated. 2. The position detecting device according to claim 1, wherein the position relationship between the area sensors is kept constant, and the position detecting device is integrated. When the position is adjusted, the integrated position detecting device is mounted on the image carrier of the image forming apparatus main body. 2. The optical scanning apparatus according to claim 1, wherein the optical scanning device is mounted in place of the optical scanning device to detect a position indicating an arrangement relationship between the optical scanning devices, and to perform position adjustment based on a shift amount in the position detection result. How to adjust the position of the device. 3. An area sensor of the position detecting device is capable of detecting at least a write start position at a write start timing by the optical scanning device, and detects an amount of deviation due to a difference between write start position signals detected by each area sensor. 3. The position adjusting method for an optical scanning device in an image forming apparatus according to claim 1, wherein the position is recognized and adjusted to be at the same position. 4. An area sensor of the position detection device is capable of detecting an end position at a write end timing by the optical scanning device, and a difference between the position detection and a position detection from the area sensor detecting the write start position. 4. The position adjustment of the optical scanning device in the image forming apparatus according to claim 3, wherein the position of the optical scanning device in the image forming apparatus is recognized and recognized as a deviation amount of the magnification in the optical scanning direction, and the clock frequency for optical scanning drive is controlled based on the deviation amount. Method. 5. After adjusting the inclination of an optical scanning line of the plurality of optical scanning devices with reference to one of the plurality of optical scanning devices, adjusting the optical scanning lines of the other optical scanning devices so as to match with each other; 3. The method for adjusting the position of an optical scanning device in an image forming apparatus according to claim 1, wherein the amount of deviation between the optical scanning devices is adjusted thereafter. 6. The apparatus according to claim 1, wherein the amount of deviation of each optical scanning device based on the position detection by each area sensor by the position detection device is displayed, and adjustment can be performed according to the display. 3. The position adjusting method of the optical scanning device in the image forming apparatus according to 2.