JPH05119572A - Color image forming device - Google Patents

Abstract

PURPOSE:To attain an image formation of high definition by carrying out positioning of each color dot in a sub scanning direction in the color image forming device simply and with high precision and preventing color slippage. CONSTITUTION:In the color image forming device obtaining a multi color or a full color image by placing a multiple number of main scanning exposure devices 120, 220, 320, and 420 carrying out scanning and exposure in a multiple number of positions on an image forming body 11 concerning the sub scanning movement direction of one image forming body, a multiple number of electrifying devices corresponding to positions irradiated by each scanning beam by this exposure device, and a multiple number of developing devices 130..., forming a superposed toner image on the image forming body, and then, transferring, and fixing this, writing of each image of the sub scanning direction is matched by forming a developing pattern in a non image forming part in the vicinity of an edge of the image forming body by an electrifying device which is most upstream in the sub scanning direction of the non image range on the surface side edge of the image forming body, the main scanning exposure device, and the developing device, having the developing pattern irradiated by the main scanning beams of the multiple number of main scanning exposure devices downstream, receiving the reflected beam at a beam receiving sensor, having the developing pattern detection signal generated in the sub scanning direction, and starting writing of the image after a specified timing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus in which a toner image is formed on an image forming body by an electrophotographic method and is transferred onto a transfer material to obtain an image.

[0002]

2. Description of the Related Art As an image forming method for obtaining a color image by using an electrophotographic method, for example, JP-A-60-75850 and 60-767.
As disclosed in No. 66, No. 60-95456, No. 60-95458, No. 60-158475, etc., latent image formation and development according to the number of separated colors of the original image on the image forming body are performed. There is a method in which a color toner image is repeatedly formed on the image forming body and then transferred to obtain a color image.

A color image forming apparatus to which an image forming method in which latent images are formed and developed according to the number of separated colors of a document image read by a color scanner on the image forming body is applied is a belt-shaped image as a first example. An exposure device and a development device corresponding to the number of separated colors (for example, three colors of yellow, magenta, and cyan or four colors including black) are arranged around the formed body, and a drum-shaped image formed body as a second example. There is an apparatus in which an exposing device and a developing device according to the number of colors are arranged around the.
Next, of these, a color image forming apparatus including a belt-shaped image forming body will be described.

In a color image forming apparatus, a tension roller is attached to a belt-shaped image forming body in which a photoconductor is applied or vapor-deposited on a flexible belt, and a tension roller is used to slide a tension roller against a reference guide member. By rotating while keeping the contact state, the surface of the belt-shaped image forming body is always kept at a constant position and conveyed, and a charger, an exposure device, and color toners of different colors are provided around the belt-shaped image forming body. An image forming unit composed of a plurality of developing devices accommodating (yellow, magenta, cyan, black) is arranged, and these image forming units are arranged at regular intervals on a belt-shaped image forming body which rotates.

[0005]

In a color image forming apparatus, as a measure for preventing color misregistration in the sub-scanning direction, for example, a resist mark is formed on an image forming body, the resist mark is detected by a photo coupler, and the detection signal is detected. By sequentially starting exposure from a plurality of exposure devices arranged based on
It is conceivable to start latent image formation at the same point on the image forming body.

However, in the color image forming apparatus, the timing for starting exposure from each exposure device by reading the registration mark formed on the belt-shaped image forming body with a single photocoupler or a plurality of photocouplers is used. Even if it is decided, in this method, the positional relationship between the photocoupler and the exposure device and the arrangement interval of the plurality of exposure devices need to be positioned with strict accuracy (± 0.01 to 0.1 mm or so). It was difficult to position the array interval of the exposure apparatus and the exposure apparatus with mechanical accuracy (the limit is about ± 0.3 to 0.5 mm at the time of filing of the present application). Furthermore, when the exposure apparatus is removed for maintenance or the like, it is extremely difficult to set the exposure apparatus at the same position again.

Further, in the color image forming apparatus for forming a color toner image by superposing a plurality of toner images (Y, M, C, K) on the image forming body as described above, a plurality of exposure apparatuses are used. If the exposure start position on the belt-shaped image forming body cannot be set to a pixel unit, for example, a deviation of about 80 μm or less, there is a problem that the image quality of the color toner image is deteriorated. In particular, when the belt-shaped image forming body is used, it is difficult to perform the alignment control as compared with the drum-shaped image forming body.

Further, the above-described method of detecting the position of a pattern image (resist mark) previously provided on the image forming body (photoreceptor) or the transfer body by a photocoupler, or the toner image on the photoreceptor or the transfer body is detected. The method of forming and detecting this using a dedicated photocoupler for position detection is disadvantageous in terms of space and cost because a dedicated photocoupler is provided and controlled, and the image quality is significantly deteriorated. ..

Further, in the sub-scanning direction, that is, the rotating direction of the image forming body, the surface speed is caused by the speed fluctuation of the driving source, the eccentricity of the intermediate driving force transmitting means, and the expansion and contraction of the belt-shaped image forming body due to the temperature and humidity changes. Each image writing position in the sub-scanning direction fluctuates due to fluctuations and the like, registration accuracy in the sub-scanning direction deteriorates, accurate position superposition of the color images cannot be obtained, and image quality deteriorates.

[0010]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present invention provides a variation in the mounting position of an image forming body in a writing unit of a color image forming apparatus, a shift in the writing position due to a temperature change, and an image formation. Corrects the positional deviation of the laser beam in the sub-scanning direction due to the speed fluctuation when the body rotates,
A color image whose purpose is to prevent color misregistration by preventing the exposure start point that forms the latent image from shifting when repeatedly performing the latent image formation multiple times without positioning with strict mechanical precision. It is to provide a forming apparatus.

The color image forming apparatus of the present invention which achieves the above-mentioned object relates to the sub-scanning moving direction of one image forming body,
A plurality of main-scanning exposure devices that perform main-scanning exposure to a plurality of positions on the image forming body, a plurality of charging devices corresponding to the irradiation positions of each scanning light by the exposure device, and a plurality of developing devices are arranged. In a color image forming apparatus that forms a superimposed toner image on an image forming body and obtains a multi-color or full-color image by transfer and fixing, in a sub-scanning direction of a non-image area of a surface side edge of the image forming body. A developing pattern is formed in the non-image forming portion near the side edge on the image forming body by the charging device, the main scanning exposure device and the developing device on the most upstream side,
The development pattern is irradiated with main scanning light from a plurality of main scanning exposure devices on the downstream side, the reflected light is received by a light receiving sensor, a development pattern position detection signal in the sub-scanning direction is issued, and an image is written after a predetermined timing. It is characterized in that the writing of each image in the sub-scanning direction is made to coincide with the start of.

The color image forming apparatus of the present invention is
With respect to the moving direction of the image forming body, the main-scanning exposure device and the developing device on the most upstream side of the image forming body are used to develop a non-image forming portion near the side edge of the image forming body with a transparent toner. A pattern is formed, the development pattern is irradiated with main scanning light of a plurality of main scanning exposure devices on the downstream side, the transmitted light is received by a light receiving sensor, a development pattern position detection signal is issued, and after a predetermined timing, the image It is characterized in that the writing of each image in the sub-scanning direction is matched by starting the writing.

Further, in the color image forming apparatus of the present invention, a part of the non-image area of the image forming body is spot-irradiated by using scanning exposure light from at least one of the plurality of exposing apparatuses, A change in the surface potential of the spot irradiation portion of the image forming body is detected by using a potential sensor provided in the vicinity of the image forming body to generate a spot irradiation position detection signal,
It is characterized in that the writing start position of each image in the sub-scanning direction is matched by starting writing the image after a predetermined timing has elapsed.

[0014]

Embodiments of the present invention will now be described with reference to the accompanying drawings.

FIG. 1 is an overall configuration diagram of a color printer as an example of a color image forming apparatus having a belt-shaped image forming body as an embodiment of the present invention.

In FIG. 1, the color image forming apparatus of this embodiment has a plurality of chargers 11 around the belt-shaped image forming body 1.
0, 210, 310, 410, exposure scanning lines L1, L2, L3
L4 and developing device 13 loaded with four different color toners
Image forming means consisting of 0, 230, 330, and 430 are arranged, and the yellow, magenta, cyan, and black toner images are superposed by one rotation of the image forming body 1 to form a color image.

The belt-shaped image forming member 1 is a belt-shaped photosensitive member (hereinafter referred to as a photosensitive member belt) in which a photoconductor is applied or vapor-deposited on a flexible belt, and the rotating roller 2 is used.
3 and a guide member 4 having a curvature, and a tension roller 5 is attached to the photosensitive belt 1, and the tension due to the pressure contact keeps the sliding contact state with respect to the reference guide member 4. By rotating, the surface of the photoreceptor belt 1 is always kept at a constant position for conveyance. With the above-described structure, the photosensitive member on the outer peripheral surface of the photosensitive belt 1 is always kept in a constant relation position with respect to the surface of the guide member 4 even during conveyance, and a stable image forming surface having a large curvature is formed with a long width. Therefore, a large number of image forming means having the same shape can be arranged in parallel at regular intervals.

Further, in this embodiment, the photoconductor belt 1 is used as the image forming body, but the present invention is not limited to this, and can be applied to an existing image forming body having a photosensitive layer such as a photoconductor drum. Applicable.

Around the photosensitive belt 1, a plurality of charging means, a plurality of exposing means, four developing means loaded with toners of different colors, a transferring means and a cleaning means are arranged.

The charging means is provided to uniformly charge the photosensitive layer on the surface of the photosensitive belt 1 with a predetermined polarity, and the existing charging devices 110, 210, 310, such as a corona charging device and a scorotron charging device are used. It is 410.

The exposure means is a semiconductor laser writing unit (laser scanning exposure device) 120, 220, 320, 420,
The surface of the photosensitive belt 1 charged by the chargers 110, 210, 310, 410 is exposed to form an electrostatic latent image.

The developing means is composed of four developing devices 130 each containing a different color developer, for example, a yellow (Y), magenta (M), cyan (C) and black (K) color toner (developer). , 230, 330, 430. Each of the developing devices 130 to 430 has a function of developing the electrostatic latent image on the photosensitive belt 1 into a toner image by a non-contact developing method.
Unlike the contact development method, this non-contact development method does not impair the previous toner image formed on the photosensitive belt 1, and
Since the movement of the photosensitive belt 1 is not hindered, a good color image can be obtained.

The transfer means transfers the toner image formed on the photosensitive belt 1 onto the transfer material by the transfer device 14 such as a transfer corona discharger. As this transfer means, an existing transfer member such as a transfer drum may be used instead of the transfer device 14.

The cleaning means 15 has a cleaning blade 151 and a cleaning roller 152.
It is provided so as to be pressed against the surface of the photoconductor belt 1 to clean the photoconductor belt 1.

The color image forming process by the image forming apparatus having the above-mentioned structure is performed as follows.

First, when the image signal of the first color output from the image reading device separate from the main body of the device is input to the laser scanning exposure device 120, the laser scanning exposure device 120.
A laser beam is generated by the semiconductor laser 121 (see FIG. 2) in FIG. The laser beam is rotationally scanned by the polygon mirror 124 rotated by the drive motor 123 via the collimation lens 122, passes through the fθ lens 125 and the cylindrical lens 126, and is uniformly charged to a predetermined charge by the chargers 110 to 410 in advance. The bright lines are formed by being projected on the peripheral surface of the photosensitive belt 1 thus made.

On the other hand, the sub-scanning direction will be described in detail later, but after the image forming start signal is issued from the machine body, the semiconductor laser 121 is started to be modulated by the image signal after a lapse of a predetermined time. , The image start position in the sub-scanning direction is determined. When the scanning is started, with respect to the main scanning direction, the fixed position of the laser beam of the first semiconductor laser 121 in the main scanning direction is detected by the PS 1, and a predetermined time elapses based on the detected signal, and the first position is detected. The modulation of the semiconductor laser 121 by the image signal of the color is started, and the modulated laser beam scans the surface of the photosensitive belt 1.
Therefore, a latent image corresponding to the first color is formed on the surface of the photosensitive belt 1 which is uniformly charged by the main scanning by the laser light and the sub scanning by the conveyance of the photosensitive belt 1. At this time,
With the start of the image, the semiconductor laser 121 forms a latent image serving as a registration mark immediately before the image start position and at a specific position on the photosensitive belt 1. These latent images are developed by the developing device 230 containing the yellow toner, and a yellow toner image is formed on the surface of the photosensitive belt 1.
Thereafter, the photosensitive belt 1 is conveyed while holding the yellow toner image on the surface thereof, and then the image formation of the second color is started.

That is, when the photosensitive belt 1 on which the yellow toner image is formed is conveyed to the next position of the charger 210, it is charged again by the charger 210. Then second
The specific position (registration mark position) of the photoconductor belt 1 is detected by the laser beam of the semiconductor laser, and the modulation of the semiconductor laser of the laser scanning exposure device 220 is started by the second image signal based on this detection signal. The laser light generated by the semiconductor laser is rotationally scanned by the polygon mirror rotated by the drive motor through the collimation lens, and is uniformly charged to a predetermined electric charge by the charger 210 through the fθ lens and the cylindrical lens. A latent image is formed by being projected on the peripheral surface of the photosensitive belt 1. The latent image is developed by the developing device 230 containing magenta toner as the second color. The magenta toner image is formed in the presence of the already formed yellow toner image.

Similarly, the photosensitive belt 1 on which the magenta toner image of the second color has been formed is further conveyed, and as in the case of the image signal of the second color, the charger 310 continues to remove the image. Developing device 330 that is charged in the same manner, forms a latent image by the laser scanning exposure device 320, and contains cyan toner.
To develop a cyan toner image. Further, the photosensitive belt 1 on which the cyan toner image of the third color is formed is further conveyed and is uniformly charged by the charger 410 as in the case of the image signals of the second and third colors. A latent image is formed by the laser scanning exposure device 420, a developing device 430 containing black toner develops the latent image, and the black toner images are superposed to form a color toner image on the surface of the photosensitive belt 1. That is, a color toner image is formed during one rotation of the photosensitive belt 1.

A DC or further AC bias is applied to each of the developing devices 130 to 430, and reversal development (jumping development) is performed in a non-contact manner on the photosensitive belt 1 whose base is grounded. .. For this non-contact development, either one-component developer or two-component developer can be used. When a one-component developer is used, it is not necessary to provide a toner concentration control means, and downsizing can be achieved. However, the development method using a two-component developer is superior in terms of development stability, so that color reproduction is improved. preferable.

The color toner image formed on the surface of the photosensitive belt 1 as described above is supplied from the paper feed cassette 161 by the paper feed roller 162, and the timing roller 163 transfers the color toner image in timing with the transfer material. Is transcribed to. The transfer device 14 applies a high voltage power source having a polarity opposite to that of the toner to transfer the toner.

Thus, the transfer material on which the color toner image has been transferred is reliably separated along the rotating roller 2 by the photosensitive belt 1 which rapidly changes its direction (small diameter curvature).
After the toner is melted and fixed by the fixing means 17, the paper is ejected from the apparatus main body by the paper ejection roller 18.

On the other hand, after the transfer of the color toner image onto the transfer material, the photosensitive belt 1 is further conveyed in the clockwise direction,
Cleaning blade 151 and cleaning roller 152
The residual toner is removed and cleaned by the cleaning means 15 in the pressure contact state. After the cleaning is completed, a new image forming process is started again.

The color image forming apparatus of this embodiment is
An image forming means including a plurality of chargers 110 to 410, exposure devices 120 to 420, and developing devices 130 to 430 loaded with toners of four different colors is arranged around the photoconductor belt 1. This is a so-called one-pass method in which the yellow, magenta, cyan, and black toner images are superposed in one rotation to form a color image. Needless to say, the present invention is not limited to the one-pass method, and may be a multi-rotation method in which a latent image is formed and developed each time the image forming body makes one rotation.

Further, the color printer of FIG. 1 has a compact design with a refracting optical system using a plurality of mirrors in order to arrange four series of exposure devices.

Next, a first embodiment will be described in which the position of the photosensitive belt 1 provided in the color image forming apparatus according to the present invention in the sub-scanning direction is detected, and the misregistration is corrected to register the registration of a plurality of images. This will be described in more detail.

FIG. 2 is a perspective view showing the optical paths of the belt-shaped image forming body and the laser scanning exposure device. The latent image of the exposure scanning line L1 is formed on the surface of the photoreceptor belt 1 which is charged in advance by the laser light of the laser scanning exposure device 120, and prior to this, the reference line (registration mark) 1A is formed near the side edge of the non-image area. And a 1B latent image is formed. The reference line 1A,
1B is developed by the first developing device 130 to form visible image reference lines 1A and 1B. PS1 is a beam detector (light receiving sensor), which receives the laser light incident from the rotary polygon mirror 124 via the fθ lens 125 and outputs an output signal,
The beam detect detection circuit outputs a rectangular wave beam detect signal based on an arbitrary set value.

The reference lines 1A and 1B are formed with latent images by exposure to laser light after the time set by the reference line count setting unit after the beam detect signal is generated.

FIG. 3 is a block diagram of scanning exposure correction for preventing deviation of the laser beam in the main scanning direction and the sub scanning direction. Here, the sub-area counter is a counter that shifts the sub-scanning direction, and the sub-count setting unit is the second image to the fourth image after the writing of the reference line 1B for the first image exposure (laser scanning exposure device 120). Exposure (laser scanning exposure device 220, 3
20, 420), a portion for setting the timing from the reference detection value of the reference line 1B to the start of image writing in the sub-scanning direction, the main area counter for moving the main scanning direction, and the main count setting unit for the first Regarding the image exposure (laser scanning exposure device 120), after writing the reference line 1A, the second to fourth image exposures (laser scanning exposures 220, 320, 42) are performed.
Regarding 0), it is a part for setting the timing from the reference detection value of the reference line 1A to the start of image writing in the main scanning direction.

A plurality (usually three) of main-scanning exposure beams downstream from the main-scanning line L1 illuminate the visualized reference lines 1A and 1B during scanning, and the reflected light thereof is received by a light-receiving sensor. The main scanning direction and sub-scanning direction start positions of the photoconductor belt 1 are detected and controlled by receiving light from PS2, PS3, and PS4.

That is, the first main scanning line L1 is detected by the light receiving sensor PS1 in the sub-scanning direction of position detection by the well-known method, after dT _V ′ is counted by the sub-area counter section.
In the main scanning direction performs image exposure after dT _H 'counted by the main area counter unit, to form a first image by the developing device 130 (e.g., yellow image).

Next, the writing laser light on the main scanning line L2 irradiates the reference lines 1A and 1B developed and formed on the rotating photosensitive belt 1, and the reflected light is received by the light receiving sensor PS2. reference line 1A, 1B after the detection signal generated in the sub-scanning direction, a predetermined timing dT _v after the main after a certain lapse of main scanning timing dT _H in the scanning direction, the second image by the main scanning line L2 (e.g., magenta Start writing the color image).

Similarly, the reference lines 1A and 1B made of the developing toner visualized on the photosensitive belt 1 are formed.
Each time the main scanning lines L3, L4 pass through, the reference lines 1A, 1B are illuminated by the exposure of the main scanning lines L3, L4 themselves, and a position detection signal is emitted by the light receiving sensor PS2, so that each color (cyan, black) The images of the respective colors are written at fixed positions on the photosensitive belt 1, and the images are superimposed.

In the present embodiment, the arrangement order of the toner colors of the developing devices 130 to 430 is not limited to Y, M, C and K, and for example, the first development reference line 1A can be easily detected. Therefore, the first developing device 130 may be loaded with black (K) toner.

Since the light receiving sensors PS1 to PS4 can be installed at a position close to the surface of the photosensitive belt 1, the writing start control detection accuracy in the sub-scanning direction is high, and the light receiving sensors PS1 to PS4 can be installed only on one end surface side of the photosensitive belt 1. Therefore, the space for the light receiving sensor can be minimized. Also, unlike using a dedicated photocoupler, since the laser light itself that uses the light source for image formation is used, the light receiving sensor can be at a low-cost phototransistor level, and the reflected light of the laser light can be emitted from the light receiving unit. It is sufficient if the position is set so that it goes inside, and the mechanical alignment accuracy is sufficient. The reference lines 1A and 1B and the light receiving sensor PS
2, PS3 and PS4 are not limited to the detection of reflected light of laser light, but can be applied to detection of reflected light in main scanning exposure using an LED array.

Next, FIG. 4 shows a laser scanning exposure apparatus of the color image forming apparatus of the second embodiment.

In this embodiment, a transparent zone is provided in the vicinity of the reference line 1A, which is provided near the side edge of the non-image area of the photosensitive belt 1, and the transparent zone.
That is, the first developing device 13 corresponding to the first main scanning light L1
The toner color of the developer housed in 0 can be transmitted by the main scanning laser light. The reference line (development pattern) 1A visualized by the developing device 130 is transmitted by being irradiated with the main scanning light L2, and the transmitted light is detected by the light receiving sensor PS12, as in the first embodiment. After a predetermined timing dT has elapsed according to the detection signal, the image signal serves as a reference in the main scanning direction.

The main scanning lights L3 and L4 are similarly written by the detection signal of the reference line 1A visualized.

FIG. 5 shows a third embodiment according to the present invention.
FIG. 6 is an overall configuration diagram of a color copying machine having a photoconductor belt 11 for forming a potential change and having an image reading system A on an upper portion thereof.
FIG. 3 is a perspective view showing an optical path of a photoconductor belt and an exposure device.

The photosensitive belt 11 whose entire surface is charged in advance by the charger 110 is a linear latent image pattern 11 which is short in the main scanning direction at a predetermined position in the non-image forming area by the main scanning light L1.
B is formed instantly. The latent image pattern 11B causes a change in the surface potential of the photosensitive belt 11.

Each exposure apparatus has sensors PS11, PS22, PS3 for controlling the position of each laser beam in the main scanning direction.
3, PS44 is provided.

Each main scanning light L2, L in the traveling direction of the photoconductor
Surface potential sensors SS2 and SS are provided on the upstream sides of L3 and L4.
3 and SS4 are fixed respectively. Photoconductor belt 11
By the sub-scanning movement (X direction) of the latent image pattern 11B
When passing through the surface potential sensor SS2 immediately before the main scanning light L2, the potential change of the latent image pattern 11B is detected by the surface sensor SS.
2 detects, generates the reference position signal, after a predetermined time dT _v elapsed, and in the main scanning direction, after the timing dT _H constant after detection of the beam detector PS22, start writing second image To do. Main scanning lines L3, L
Similarly, in the case of 4, the surface potential sensors SS3 and SS4 perform image writing after the reference position of the latent image pattern 11B is detected.

As described in each of the above embodiments, each laser scanning exposure device 120, 2 is first provided with ordinary mechanical accuracy.
After arranging 20,320,420, the focus of the laser beam is adjusted, and the photosensitive belt 1, which rotates during the image writing operation,
Even if the conveyance speed fluctuation occurs at 11, the sub-scanning line has a delicate one scan width unit or one dot width unit by the reference position setting by the sensor detection of the reference line 1B and the latent image pattern 11B and the predetermined count. The image is formed by correcting the color shift with high accuracy, and particularly in the color image formation in which the images are superposed, an excellent effect is exhibited and the color image quality is significantly improved.

[0054]

As described above, the laser scanning exposure apparatus in the color image forming apparatus of the present invention has a plurality of colors in the sub-scanning direction which is one of the most important factors for determining the recording image quality at the time of color image formation. It is possible to realize the position alignment of the dots easily and with high accuracy, prevent color misregistration, and form an excellent image. In particular, it provides an extremely effective means in the scanning exposure apparatus of the color image forming apparatus of the superposition method including the electrophotographic method.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing a first embodiment of a laser scanning exposure device of a color image forming apparatus of the present invention.

FIG. 3 is a control block diagram of the laser scanning exposure apparatus.

FIG. 4 is a perspective view of a laser scanning exposure apparatus according to a second embodiment of the present invention.

FIG. 5 is an overall configuration diagram of a third embodiment of a color image forming apparatus according to the present invention.

FIG. 6 is a perspective view of a laser scanning exposure apparatus according to the third embodiment.

[Explanation of symbols]

1,11 Belt-shaped image forming body (photosensitive belt) 1A, 1B Reference line (registration mark) 2,3 Rotating roller 4 Guide member 11A, 11B Latent image pattern (registration mark) 110, 210, 310, 410 Charger 120, 220, 320, 420 Laser scanning exposure device (laser writing unit) 121 Laser light source (semiconductor laser) 124 Polygon mirror (rotary polygon mirror) 125 fθ lens 130, 230, 330, 430 Developer L1, L2, L3, L4 Main exposure scanning line PS1, PS2, PS3, PS4, PS11 Light receiving sensor
(Beam detector) SS2, SS3, SS4 Surface potential sensor W Image area width

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location G03G 15/04 116 9122-2H H04N 1/29 G 9186-5C (72) Inventor Jun Ogane Tokyo Konica Co., Ltd., 2970 Ishikawacho, Hachioji, Tokyo (72) Inventor Isao Matsuoka Konica Co., Ltd., 2970 Ishikawacho, Hachioji, Tokyo (72) Tadayoshi Ikeda Tachiyoshi Ikeda, 2970 Ishikawacho, Hachioji, Tokyo

Claims (6)

[Claims] 1. Corresponding to a plurality of scanning exposure devices that perform main scanning exposure to a plurality of positions on the image forming body in the sub-scanning movement direction of one image forming body, and irradiation positions of each scanning light by the exposing device. In the color image forming apparatus, a plurality of charging devices and a plurality of developing devices are arranged to form a superimposed toner image on the image forming body, and transfer and fixing are performed to obtain a multi-color or full-color image. A non-image forming portion near the side edge on the image forming body is developed by a charger, a main-scanning exposure device, and a developing device, which are on the most upstream side in the sub-scanning direction of the non-image area on the side edge of the image forming body. A pattern is formed, the development pattern is irradiated with main scanning light from a plurality of main scanning exposure devices downstream, the reflected light is received by a light receiving sensor, a development pattern position detection signal in the sub-scanning direction is issued, and a predetermined timing elapses. After the image book By starting a write, the color image forming apparatus characterized by match the writing in the sub-scanning direction of each image. 2. A plurality of main-scanning exposure devices that perform main-scanning exposure to a plurality of positions on the image-forming body in the sub-scanning moving direction of one image-forming body, and irradiation positions of each scanning light by the exposure device. In a color image forming apparatus in which a plurality of corresponding charging units and a plurality of developing units are arranged to form a superposed toner image on an image forming body, and transfer and fixing are performed to obtain a multi-color or full-color image, With respect to the moving direction of the image forming body, the main-scanning exposure device and the developing device on the most upstream side of the image forming body are used to develop a non-image forming portion near the side edge of the image forming body with a transparent toner. A pattern is formed, the development pattern is irradiated with main scanning light of a plurality of downstream main scanning exposure devices, the transmitted light is received by a light receiving sensor, a development pattern position detection signal is issued, and after a predetermined timing elapses, By initiating the writing of an image, a color image forming apparatus characterized by match the writing in the sub-scanning direction of each image. 3. A plurality of main-scanning exposure devices that perform main-scanning exposure to a plurality of positions on the image forming body in the sub-scanning movement direction of one image forming body, and an irradiation position of each scanning light by the exposing device. A color image forming apparatus in which a plurality of corresponding charging units and a plurality of developing units are arranged to form a superposed toner image on an image forming body, and transfer and fixing are performed to obtain a multi-color or full-color image. Changing the surface potential of a spot irradiation unit of the image forming body by spot-irradiating a part of a non-image area of the image forming body with scanning exposure light from at least one of the plurality of exposing apparatuses. Is detected using a potential sensor provided in the vicinity of the image forming body to generate a spot irradiation position detection signal, and after a predetermined timing has elapsed, image writing is started, thereby Color image forming apparatus, characterized in that to match the writing of the image. 4. The color image forming apparatus according to claim 1, wherein the scanning exposure device is a laser beam scanning exposure device. 5. The color image forming apparatus according to claim 1, wherein the main scanning light of the scanning exposure device corresponds to four colors of yellow, magenta, cyan and black. .. 6. The color image forming apparatus according to claim 1, wherein the image forming member that moves in the sub-scanning direction is an endless belt-shaped photosensitive member.