JPH09131920A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust a position of light beam at a high precision by providing a light beam position adjusting prism for finely adjusting a light beam deviation in the vertical scanning direction which orthogonally intersects the horizontal scanning direction, in a device wherein a plurality of light beams are made to simultaneously scan in the horizontal scanning direction so as to simultaneously record a plurality of lines. SOLUTION: In a plural-light beam scanning device, light beams which are projected from semiconductor lasers 130A and 130B arranged orthogonally are made to be parallel by collimator lenses 131A and 131B and made to enter a beam synthetic prism 132. Both beam lights enter a polygon mirror 135 through an aperture 133 and a cylindrical lens 134. Next, a reflected light scans two lines simultaneously on a peripheral face of a photosensitive drum 10 through an fθ lens 136 and a cylindrical lens 137. At this time, a prism set 143 which comprises two sheets of prisms and adjusts a pitch in the vertical scanning direction is provided, which is rocked by a stepping motor so as to finely adjust a fine deflection angle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical writing device such as a laser printer, and more specifically, an image in which a plurality of light beams simultaneously scan a recording medium in parallel in a main scanning direction to record a plurality of lines simultaneously. The present invention relates to a technique for finely adjusting a deviation amount of a scanning position in the sub-scanning direction of the plurality of light beams in the forming apparatus.

[0002]

2. Description of the Related Art In a conventional optical scanning optical system for performing laser beam recording, in order to achieve high-speed scanning, it is necessary to increase the rotation speed of a deflection mirror (polygon mirror or the like), which results in high speed of an air bearing or the like. There is a problem in that high-precision manufacturing technology becomes indispensable and cost increases.

On the other hand, as disclosed in Japanese Laid-Open Patent Publication No. 54-158251, there is also known a system in which a plurality of light emitting portions of a semiconductor laser are used and a plurality of scanning lines are simultaneously scanned. However, in order to control the pitch of the scanning lines, it is necessary to precisely adjust the distance between the light emitting units and arrange them.
Furthermore, it is necessary to precisely control the angle of these light emitting portions in the arrangement direction, and therefore a highly accurate adjusting mechanism is indispensable.

Further, the scanning optical system disclosed in Japanese Patent Laid-Open No. 58-68016 has a variable scanning line pitch in the sub-scanning direction, which is disclosed in Japanese Patent Laid-Open No. 63-50809. The writing device adjusts the scanning optical path in the sub-scanning direction using two adjusting screws.

Further, the one disclosed in Japanese Patent Laid-Open No. 62-86324 relates to a two-beam laser printer for adjusting the position of the collimator unit itself.

Japanese Unexamined Patent Publication No. 7-228000 discloses a device for detecting a scanning position shift in the sub-scanning direction of two light beams of an image forming apparatus. JP-A-7-2
The image forming apparatus described in Japanese Patent No. 48458 is a technique that detects a scanning position shift amount between a plurality of light beams and corrects image recording based on the detected shift amount.

[0007]

A multi-beam optical scanning device for scanning a recording medium by deflecting a laser beam (light beam) modulated based on an image signal by a rotating polygon mirror or the like to record image information. In the case of the configuration in which multiple lines are simultaneously recorded by using multiple sets of laser beams, the scanning positions of the multiple laser beams are adjusted to match the specified position, but this scanning position changes due to changes in the environment. However, there is a problem that faithful image formation cannot be stably performed.

For this reason, while monitoring the change in the environment, when the change is out of the specified range, fine adjustment is performed again and the method has been implemented as a countermeasure. Generally, since a recording system that scans a laser beam is easily affected by temperature fluctuations, a temperature sensor that detects this temperature is provided, and the voltage output from this temperature sensor according to the temperature is A /
It is A / D converted by the D converter and output to the CPU.
The CPU obtains the temperature variation by comparing the most recently input temperature data with the temperature at the time of the last fine adjustment. For example, when it is detected that the temperature variation is ± 10 ° C. or more, the temperature is finely adjusted again. Make adjustments. By this fine adjustment, the scanning positions of the plurality of laser beams are set within the specified values.

FIG. 11 is a flow chart showing a process of adjusting the deviation by the above-mentioned temperature measurement. By the output signal from the temperature sensor and A / D converter (not shown),
The CPU performs temperature measurement calculation, and calculates the temperature fluctuation by comparing the latest measurement data and the previous measurement data.
The temperature difference due to the temperature fluctuation detected here is compared with whether it is within the range of the specified value, and if it is within the specified value, the temperature is measured again by the temperature sensor. However, if the temperature fluctuation is above the specified value, after performing fine adjustment,
Enter the temperature measurement.

However, with the circuit configuration as described above,
With the configuration for performing the fine adjustment, the temperature sensor and the A / D converter are required, and the circuit configuration becomes complicated, and
Since it becomes necessary to perform calculation to determine temperature fluctuations, CP
There is a problem that the calculation load of U increases.

An object of the present invention is to realize high speed by a simple structure and method without requiring high design technology, high precision manufacturing technology or adjusting mechanism unlike the above-mentioned conventional example, and An object of the present invention is to provide an image forming apparatus including a multiple beam light scanning device capable of adjusting the scanning line dot pitch in the scanning direction.

[0012]

An image forming apparatus of the present invention which achieves the above object is an image forming apparatus which simultaneously scans a recording medium in parallel in a main scanning direction by a plurality of light beams to record a plurality of lines at the same time. In the above, a light beam position adjusting prism for finely adjusting the amount of light beam deviation in the sub-scanning direction orthogonal to the main scanning direction and a fine adjusting means for finely adjusting the light beam position adjusting prism are provided, and the deviation by the fine adjusting means is provided. The amount fine adjustment is performed immediately before the page image is formed by the shift amount detection signal and the control unit.

Further, the image forming apparatus of the present invention is characterized in that when the image to be recorded is set to a monochrome image, the page image is formed after the light beam deviation amount fine adjustment is performed. is there.

Further, in the image forming apparatus of the present invention, when the image to be recorded is set to a color image, after the light beam deviation amount fine adjustment is performed, the page image of the first color is formed, and the second and subsequent colors are formed. The page image formation is characterized in that the image is formed based on the deviation amount correction performed before the image formation of the first color without performing the deviation amount fine adjustment for each color.

Furthermore, the image forming apparatus of the present invention is characterized in that, when the image to be recorded is a plurality of pages, the page image is formed after performing the fine adjustment of the light beam deviation amount for each page. Although it does.

Further, for the above-mentioned purpose, the fine adjustment of the light beam shift amount in the sub-scanning direction is performed by finely adjusting each beam position in the writing sub-scanning direction provided between the beam shaping optical system and the beam synthesizing prism. It is achieved by an image forming apparatus characterized in that it is performed by a prism.

As described above, according to the present invention, a plurality of sets of laser beams (light beams) modulated based on image signals are deflected by a rotating polygon mirror or the like to scan on a recording medium,
In an image forming apparatus equipped with a multi-beam optical scanning device for recording image information, when a plurality of sets of laser beams are used to simultaneously record a plurality of lines, the scanning positions of the plurality of sets of laser beams are set to a specified value. The operation of performing fine adjustment within the range is executed by the control circuit that is performed before image formation based on the page area signal indicating the image formation area.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to the description of the embodiments of the present invention, the structure and operation of a color printer which is an example of the image forming apparatus of the present invention will be described with reference to the sectional structure diagram of FIG.

In this color printer, toner images of respective colors sequentially formed on an image carrier are superposed, and then transferred at one time on a recording paper at a transfer portion to form a color image, and thereafter, an image is separated by a separating means. It is a color image forming apparatus of the type that is peeled from the surface of a carrier.

In FIG. 1, 10 is an image carrier (recording medium).
Is a photosensitive drum in which an OPC photosensitive member (organic photosensitive member) is formed by coating on a drum base, and is grounded and driven and rotated in the clockwise direction shown in the drawing. Reference numeral 12 denotes a scorotron charger, which applies uniform charge of high potential V _H to the peripheral surface of the photosensitive drum 10 by corona discharge by a grid held at a grid potential V _G and a corona discharge wire. Prior to the charging by the scorotron charger 12, exposure is performed by a PCL (pre-charging static eliminator) 11 using a light emitting diode or the like to eliminate the history of the photoconductor until the previous printing, and the peripheral surface of the photoconductor is neutralized. deep.

After the photosensitive drum 10 is uniformly charged, the image exposing means 13 performs image exposure based on the image signal. The image exposure means 13 is a means for performing a main scan in which an optical path is bent by a reflection mirror 138 after passing through a polygon mirror 131, an fθ lens 136, and a cylindrical lens 137 which rotate using a laser diode (not shown) as a light emitting source.
A latent image is formed by rotation (sub-scanning) of the photosensitive drum 10. In this embodiment, the character portion is exposed to form an inverted latent image in which the character portion has a lower potential V _L.

Around the periphery of the photosensitive drum 10, a developing device 14 (14Y) containing a developer containing toner such as yellow (Y), magenta (M), cyan (C), black (K), and a carrier, respectively. , 14M, 14C, 14K), and first, the development of yellow of the first color is performed by a developing sleeve which contains a magnet and holds the developer and rotates. The developer is a carrier coated with an insulating resin around a ferrite core, a pigment and a charge control agent according to the color with polyester as the main material,
The toner is a toner to which silica, titanium oxide, etc. are added. The developer is formed on the developing sleeve by a layer forming means.
The layer is regulated to a layer thickness (developer) of 0 to 600 μm and conveyed to the developing area.

The gap between the developing sleeve and the photosensitive drum 10 in the developing area is 0.2 to larger than the layer thickness (developer).
As 1.0mm, AC bias and V _DC of V _AC during this time
Are applied in a superimposed manner. V _DC and V _H, for charging the toner are the same polarity, the toner given the opportunity to leave from the carrier by V _AC is not adhere to a portion of the high V _H of potential than V _DC, potential than V _DC Adhered to the low V _L portion, and visualization (reversal development) is performed.

After the visualization of the first color is completed, the process proceeds to the magenta image forming process for the second color, and the scorotron charger 1 is again used.
The uniform charging by 2 is performed, and the latent image based on the image data of the second color is formed by the image exposure unit 13. At this time 1
The charge elimination by the PCL 11 performed in the color image forming process is not performed because the toner attached to the image portion of the first color scatters due to the rapid decrease in the potential around the image portion.

Again, a latent image similar to that of the first color is formed and developed on the portion of the photoconductor having the potential of V _H all over the peripheral surface of the photoconductor drum 10 without the image of the first color. However, in the portion where the first-color image is developed again, the latent image of V _M ′ is formed by the light-shielding toner of the first color and the electric charge of the toner itself.
Developing in response to the potential difference between the _DC and V _M 'is performed. In the overlapping portion of the first color image and the second color image, development of the first color is performed by V
_When the latent image of _L is formed, the balance between the first color and the second color is lost, so that the exposure amount of the first color is reduced and V _H > V _M >
In some cases, the intermediate potential may be V _L.

An image forming process similar to that for the magenta of the second color is performed for the cyan of the third color and the black of the fourth color, and a visible image of four colors is formed on the peripheral surface of the photosensitive drum 10.

Reference numeral 15 is each of the developing devices 14Y, 14M, 14
A toner replenishing device that replenishes C and 14K with new color toners.

On the other hand, the half-moon roller 1 from the paper feeding cassette 16
One sheet of the transfer material (transfer sheet or the like) P conveyed through 71 is temporarily stopped, and when the transfer timing is adjusted, it is fed to the transfer area by the rotation operation of the registration roller pair 172 of the sheet feeding section. It

In the transfer area, the transfer means 18 is pressed against the peripheral surface of the photosensitive drum 10 in synchronism with the transfer timing, and the transferred transfer material P is nipped and a multicolor image is transferred at once. It

Next, the transfer material P is destaticized by the separating means 19, separated from the peripheral surface of the photosensitive drum 10 and conveyed to the fixing device 22, where the heat roller (upper roller) 221 and the pressure roller (lower roller) 222 are separated. After the toner is fused by heating and pressurization, the toner is discharged onto a discharge tray 24 outside the apparatus via a discharge roller 23. Incidentally, the above-mentioned transfer means 1
After the transfer material P has passed through, 8 is retracted and separated from the peripheral surface of the photosensitive drum 10 to prepare for the next toner image formation.

On the other hand, the photosensitive drum 1 from which the transfer material P is separated
In No. 0, the residual toner is removed and cleaned by the pressure contact of the blade 201 of the cleaning device 20, and again the PCL 11
After the charge is removed by and the charger 12 is charged, the next image forming process starts. The blade 201 immediately moves after cleaning the surface of the photoconductor and retracts from the peripheral surface of the photoconductor drum 10. The waste toner scraped off by the blade 201 into the cleaning device 20 is discharged by the screw 202 and then stored in a waste toner collecting container (not shown).

Next, a multi-beam optical scanning device of the present invention will be described with reference to the accompanying drawings.

FIG. 2 is an overall configuration diagram showing an embodiment of the multi-beam optical scanning device of the present invention.

In the figure, 130A and 130B are semiconductor lasers, 131A and 131B are collimating lenses (beam shaping optical systems), 132 is a beam combining prism, and 13
3 is an aperture, 134 is a first cylindrical lens, 135 is a polygon mirror, 136 is an fθ lens, 1
37 is a second cylindrical lens, 138 is a mirror, 1
Reference numeral 0 indicates a photoconductor drum. 139
Is a timing detection mirror, 140 is a synchronization detector, 14
Reference numeral 1 is a drive motor for the polygon mirror 135. Further, 142 is a set of prism sets for adjusting the main scanning direction, and 143 is a set of prisms for adjusting the pitch in the sub-scanning direction.

The beam light emitted from the semiconductor laser 130A is collimated by the collimator lens 131A,
Then, it enters the beam combining prism 132. Similarly, the beam light emitted from the semiconductor laser 130B arranged orthogonally to the semiconductor laser 130A becomes parallel light by the collimator lens 131B, and then enters the beam combining prism 132. In addition, this semiconductor laser 1
The beam light emitted from 30B is arranged so as to be offset from the beam light emitted from the semiconductor laser 130A by a predetermined pitch in the sub-scanning direction. Both of the light beams pass through the aperture 133 and enter the polygon mirror 135 via the first cylindrical lens 134 of the first image forming optical system. The reflected light passes through the second imaging optical system including the fθ lens 136 and the second cylindrical lens 137, passes through the mirror 138, and is formed on the peripheral surface of the photoconductor drum 10 with a predetermined spot diameter in the sub-scanning direction. Two lines are simultaneously scanned with a predetermined pitch shift. The main scanning direction has already been finely adjusted by an adjusting mechanism (not shown). 1
The line-by-line synchronization detection is performed by using the mirror 13
It is led to the second imaging optical system via 9 and is made incident on the synchronization detector 140.

FIG. 3 is a view for explaining the beam angle adjustment of the one prism set 143. In the conventional method shown in FIG. 3A, since the collimator lens 131B is directly swung by the angle θ in order to obtain the deflection angle θ of the optical path, it is difficult to accurately adjust the angle of the collimator lens 131B. FIG. 3B shows an optical path deflecting method according to the present invention, in which a pair of prism sets 143 composed of two prisms 143A and 143B is arranged near the emitting portion of the collimator lens 131B, and the prism set 143 is arranged at an angle α. By rotating the optical path, the optical path is swung by a desired deflection angle θ of the optical path.

FIG. 4 shows the above-mentioned pair of prisms 143.
It is an optical path figure explaining the relationship of the exit deflection angle with respect to the incident angle of the prism set 143 which consists of A and 143B.

The entrance surface of the prism 143A (first
The beam incident at an angle θ1 with the normal direction of
The light is emitted from the emission surface (second surface) of the prism 143A to form a deflection angle X. The general equation of the deflection angle X is obtained by the simultaneous equations of the following equations (1), (2), (3) and (4).

Θ2 = Sin ⁻¹ (n / N · Sin θ1) ··· (1) θ3 = A1 −θ2 ··· (2) θ4 = Sin ⁻¹ (N / n · Sin θ3) ··· (3) X = (θ1−θ2) + (θ4−θ3) (4) When the two prisms 143A and 143B are used as a set, the general formula of the deflection angle Y is as follows: ), (6),
It is obtained by the simultaneous equations of (7), (8), and (9).

Θ5 = A1 + B−θ4 (5) θ6 = Sin ⁻¹ (n / N · Sin θ5) (6) θ7 = A2 + θ6 (7) θ8 = Sin ⁻¹ ( N / n · Sin θ7) (8) Y = X + (θ5-θ6)-(θ8-θ7) (9) In the above formula, A1 and A2 are prisms 143A and 143B, respectively.
Angle, B is the angle formed by the first surfaces of both prisms 143A and 143B, n is the refractive index in air (= 1.0), and N is the refractive index of the prism (FK7, 1.5107 at 780 nm).
2),

Here, the apex angles A1 and A2 of the prisms 143A and 143B are respectively 4 °, and both prisms 143A and 143A are
When the angle B formed by each first surface of 143B is set to 2.05 ° and the rotation angle α of the prism set 143 is set to 10 °, the deflection angle θ of the optical path becomes 0.065 °. That is, the angle magnification is θ / α = 0.065 / 10 = 0.0065
Therefore, the ratio of the adjustment rotation angle θ of the collimator lens 131B to the adjustment angle α of the prism set 143, θ /
Since α can be set to 1/100 or less, fine adjustment of the optical path in the sub-scanning direction can be performed by the prism set 14 having a two-element configuration.
3 can be easily performed. Similarly, the optical path adjustment in the main scanning direction is performed by one prism set 14
By rotating 3, the pitch can be easily adjusted.

FIG. 5 is a plan view of a main part of a two-beam optical scanning device according to the present invention, FIG. 6 shows a main scanning and sub-scanning beam adjusting prism unit, and FIG. 6 (A) is a plan view.
6B is a left side view and FIG. 6C is a rear view. FIG. 7 is a partial perspective view of the sub-scanning prism unit.

A prism set 143 for adjusting the pitch in the sub-scanning direction, which includes the two prisms 143A and 143B.
Are contained in a holder 144. The holder 14
Reference numeral 4 is swingably and rotatably supported by a support shaft 145.
A wheel 146 is fixed to the shaft end of the support shaft 145,
The rotation of the worm 147 causes deceleration driven rotation. The achievement ratio of the wheel 146 to the worm 147 is 1 /
It is set to 10 to 1/20. A knob 148 for manual fine adjustment is fixed to the shaft end of the worm 147. By manually rotating the knob 148, the rotation angle β of the knob 148 is adjusted to the worm 147 and the wheel 146.
The supporting shaft 145 is rotated at the reduced deceleration rotation angle α by being decelerated by the reduction ratio. Accordingly, the holder 144 integrated with the support shaft 145 and the built-in prism set 1
The reference numeral 43 oscillates in the vertical direction and is moved by a slight deflection angle θ. Therefore, the rotation angle of the knob 20 is reduced to 1/20 to 1/30 by the first-stage worm wheel reduction means, and is further reduced to about 1/100 by the swinging of the second-stage prism set 143. / 2000 to 1/300
The formation of a deceleration deflection angle θ of 0 is achieved. As a result, the knob 148 can be rotated slowly and largely to perform fine adjustment of the shake angle with high accuracy.

The worm 147 and the wheel 14
6 is a one-way drive transmission, so that the holder 144
Even if a rotational force is applied from the side, the rotation is prevented by the worm wheel means, and the knob 148 is prevented from rotating after the adjustment is completed by the knob 148 and does not move. Further, one end of a spring 149 is hooked on the holder 144, so that play such as backlash of the worm wheel means or other transmission means can be removed.

FIG. 8 is a drive control block diagram of the stepping motor 150 for swinging the prism set 143 for adjusting the light beam pitch deviation in the sub-scanning direction. A stepping motor 150 is connected to the other shaft end of the worm 147, and the worm 147 is electrically driven to rotate to swing the prism set 143 for pitch adjustment in the sub-scanning direction via the wheel 146. It is possible to perform fine adjustment of the minute shake angle θ with high accuracy. That is, when a page image area signal, a monochrome image or color image determination signal, and a sub-scanning direction deviation amount detection signal are input to the CPU from an image processing unit (not shown), the CPU based on these signals. 2 at the timing just before the image is formed.
In order to finely adjust the scanning position of the pair of laser beams, CP
U performs signal processing and arithmetic processing, and the stepping motor drive control circuit 151 controls the number of steps,
Driving the stepping motor 150, prism set 1
43 is deflected by a predetermined angle.

As described above, the pitch of the beam emitted from the semiconductor laser 130B in the sub-scanning direction can be easily and precisely adjusted by the stepping motor 150.

Further, in order to adjust the deflection angle in the main scanning direction, by providing a worm wheel means having the same structure as described above, the deflection angle of the optical path can be easily and accurately performed manually or electrically. it can. In the main scanning beam adjusting prism unit shown in FIG. 6, parts having the same functions as those of the sub-scanning beam adjusting prism unit are designated by the same reference numerals.

FIG. 9 is a flow chart showing the process of adjusting the light beam pitch deviation in the sub-scanning direction by the multiple beam light scanning device provided in the image forming apparatus of the present invention. When the image recording start signal is generated, first, fine adjustment is performed to adjust the beam positions of the plurality of laser beams to a predetermined position. After the fine adjustment, if the image to be recorded is a monochrome image, a page image is formed. If the image to be recorded is a color image, a color image is formed by the image forming process shown in FIG. 1. In this case, the page images of the first to fourth colors are not corrected for each color, and
An image is formed based on the fine adjustment performed before the image formation of the first color. If there are a plurality of pages of images, fine adjustment is performed again for each page, and image formation is performed in the same manner as the processing described above.

The image forming apparatus provided with the multi-beam optical scanning apparatus according to the present invention can be applied to a system other than the color image forming apparatus shown in FIG. That is, a method of sequentially transferring a toner image of a single color onto the image bearing member while forming a single color toner image on the photosensitive drum 10 (referred to as a sequential transfer method and shown in FIG. 10), or a single color toner image is formed on the photosensitive drum 10 a plurality of times. Any of the methods of developing the toner images and then transferring them all at once onto the transfer paper (referred to as a batch transfer method) is applicable.

An image forming method by the color image forming apparatus of the successive transfer type shown in FIG. 10 will be described. A scorotron charger 1 for applying a charge to the surface of the photoconductor drum 10 by corona discharge in the vicinity of the peripheral surface of the photoconductor drum 10 having a photosensitive layer for forming an electrostatic latent image on a conductive substrate.
2, an exposure optical system 13, developing devices 14Y, 14M, 14C, 14K in which a plurality of developing devices storing a monochromatic developer are arranged,
A cleaning device 20 for cleaning the toner remaining on the photosensitive drum 10 is arranged. On the other hand, a transfer unit 31 that supplies the transfer paper P to the transfer drum 30 is disposed on the transfer drum 30 side including the conductive substrate, the conductive elastic layer, and the insulating layer, and the transfer paper supplied from the transfer unit 31. P is conveyed to a transfer portion where the transfer pole 32 is arranged, and the toner image of the photosensitive drum 10 developed with toner of different colors is transferred onto the transfer paper P, and this is repeated several times to transfer a multicolor image to the transfer paper. The transfer paper P is formed on the surface of P, transferred to a peeling portion, the charge of the transfer drum 30 is removed by the peeling electrode 33, and the transfer paper P is peeled from the transfer drum 30 and discharged. A multicolor image is formed by fixing the transfer paper P with a melt pressure type fixing device.

[0051]

As described above, according to the image forming apparatus of the present invention, the fine adjustment of the scanning position of two sets of laser beams (light beams) is performed based on the page image area signal indicating the image forming area. Since it is performed before the image formation, the scanning position of the laser beam is finely adjusted for each image formation. That is, the fine adjustment function is activated in advance for each image formation regardless of detection of temperature fluctuations, which makes it possible to finely adjust the scanning positions of a plurality of laser beams with a simple circuit configuration. By the fine adjustment for each image formation, the image can be always formed in a stable state. The fine adjustment can be performed in a light beam scanning device including two or more sets of semiconductor lasers.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram of a color printer as an example of an image forming apparatus of the present invention.

FIG. 2 is an overall configuration diagram of a two-beam optical scanning device according to the present invention.

FIG. 3 is a diagram for explaining beam angle adjustment of one prism set.

FIG. 4 is an optical path diagram of one prism set.

FIG. 5 is a plan view of a main part of a two-beam optical scanning device according to the present invention.

6A and 6B are a plan view, a left side view and a rear view of a main scanning and sub scanning beam adjusting prism unit.

FIG. 7 is a partial perspective view of a sub-scanning prism unit.

FIG. 8 is a drive control block diagram of a stepping motor for adjusting a light beam in the sub-scanning direction.

FIG. 9 is a flowchart showing a process of finely adjusting the light beam in the sub-scanning direction by the multi-beam light scanning device.

FIG. 10 is a configuration diagram of a sequential transfer type color image forming apparatus.

FIG. 11 is a flowchart showing a process of performing fine adjustment by conventional temperature measurement.

[Explanation of symbols]

 10 Photoconductor drums (recording medium, image carrier) 130A, 130B Semiconductor lasers 131A, 131B Collimating lens 132 Beam combining prism 134 First cylindrical lens 135 Polygon mirror (deflector) 136 fθ lens 137 Second cylindrical lens 141 Drive motor 142 Prism set for main scanning direction adjustment 142A, 142B, 143A, 143B Prism 143 Prism set for vertical scanning direction pitch adjustment 144 Holder 150 Stepping motor 151 Stepping motor drive control circuit θ, X, Y Optical path deflection angle

Claims (7)

[Claims] 1. An image forming apparatus that simultaneously scans a recording medium in parallel with a main scanning direction by a plurality of light beams to simultaneously record a plurality of lines, wherein a light beam deviation amount in a sub-scanning direction orthogonal to the main scanning direction is provided. Is provided with a light beam position adjusting prism and fine adjusting means for finely adjusting the light beam position adjusting prism, and fine adjustment of the deviation amount by the fine adjusting means forms a page image by the deviation amount detection signal and control means. An image forming apparatus, which is carried out immediately before. 2. The image forming apparatus according to claim 1, wherein when the image to be recorded is set to a monochrome image, the page image is formed after the fine adjustment of the light beam deviation amount is performed. 3. When the image to be recorded is set to a color image, after performing the light beam deviation amount fine adjustment, a page image of the first color is formed, and in the page image formation of the second and subsequent colors, each color image is formed. The image forming apparatus according to claim 1, wherein the image is formed based on the deviation amount fine adjustment performed before the image formation of the first color without performing the deviation amount fine adjustment. 4. When the image to be recorded has a plurality of pages, the page image is formed after performing the light beam deviation amount fine adjustment for each page. The image forming apparatus according to item 1. 5. The fine adjustment of the light beam shift amount in the sub-scanning direction is performed by a prism for finely adjusting each beam position in the writing sub-scanning direction provided between the beam shaping optical system and the beam combining prism. 5. A method according to any one of claims 1 to 4, characterized in that
The image forming apparatus according to claim 1. 6. The sub-scanning direction fine adjustment means of the plurality of light beams comprises four sets of image forming means including a corona discharge device, an image exposure means, and a developing device, and a transfer device in the circumferential direction of a rotating image carrier. Means and a cleaning device are arranged, and during one rotation of the image carrier, charging, image exposure and development are repeated on the peripheral surface of the image carrier to superimpose toner images of different colors to form a color toner image. The image forming apparatus according to claim 1, wherein the image forming apparatus is mounted on a color image forming apparatus that forms and transfers the color toner image onto a transfer material by a transfer unit. 7. The sub-scanning direction fine adjustment means for the plurality of light beams includes an image forming means including a corona discharge device, an image exposure means, and a plurality of developing devices, and a transfer means in a circumferential direction of a rotating image carrier. And a cleaning device are arranged, and while the image carrier is rotated a plurality of times, a toner image of a different color is superposed on the peripheral surface of the image carrier by repeating charging, image exposure and development to form a color toner image. The image forming apparatus according to claim 1, wherein the image forming apparatus is mounted on a color image forming apparatus that forms and transfers the color toner image onto a transfer material by a transfer unit.