JPS63271275A - Multiple image forming device - Google Patents

Abstract

PURPOSE:To simply remove a positional deviation between plural images on a transfer material by providing the titled device with a detecting means for detecting a positional deviation detecting mark and a correcting means for correcting plural positional deviation elements based on a detected result. CONSTITUTION:Image register marks 34, 35 for detecting image positions on a transfer belt 6a are formed in each color a fixed interval by an electrophotographing process. Two CCDs 14, 15 are used as sensors for reading out these marks 34, 35. The color shift of the register marks 34, 35 formed on the transfer belt 6a is read out by the CCDs 14, 15 through lamps 16, 17 arranged on the downstream side from a final station and condenser lenses 18, 19 and correction is executed by feedback control. Thus, a stable image free from positional deviation can be formed by detecting a positional deviation and correcting image formation based on the detected result.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multiple image forming apparatus that forms images on a plurality of image carriers to obtain multiple images on the same transfer material.

[Conventional technology]

2. Description of the Related Art Conventionally, as a multiplex image forming apparatus having a plurality of optical scanning means, one shown in FIG. 11, for example, is known. FIG. 11 is a schematic diagram showing an image forming apparatus with a full set of four drums, and in the same figure, 101c, IOIM,
10IY and 10IBK are image forming stations that form images of cyan, magenta, yellow, and black, respectively, and the image forming station 10
IC, IOIM, l0IY.

101BK are photosensitive drums 102C and 102M, respectively.

102Y, 102BK, optical scanning means 103C, 10
3M.

Transfer material S includes 103Y, 103BK, a developer, and a cleaner, and moves in the direction of arrow A by a transfer belt 106.
Image 31 of cyan, magenta, yellow, and black on top
A color image is formed by sequentially transferring C, 31M, 31Y, and 3113K.

In this way, in an apparatus having a plurality of image forming stations, images of different colors are sequentially transferred onto the same surface of the same transfer material S, so if the transferred image position at each image forming station deviates from the ideal position, for example, In the case of color images, this results in deviations or overlap between images of different colors, and in the case of color images, differences in color tone, and in severe cases, blurring of colors, which significantly deteriorates the quality of the image. .

By the way, the first type of positional deviation of the transferred image is
As shown in Figure 2 (a), (b), (c), and (d), the positional deviation (top margin) in the transfer material S transport direction (A direction in the figure) (Figure 2 (a)), and the scanning direction (A in the diagram
B direction perpendicular to the direction) (left margin)
((b) in the same figure), tilt shift in the diagonal direction ((C) in the same figure),
There is a shift in magnification error ((d) in the same figure), and in reality, the above 4.
A combination of different types appears.

The main cause of the above-mentioned image deviation is the difference in the image writing timing of each image forming station in the case of the top margin in FIG. This is a deviation in the writing timing of each image, that is, the scanning start timing in one scanning line.In the case of a tilt deviation in the diagonal direction shown in Fig. 13(c), the mounting of the scanning optical system is caused by an angular deviation θ1 (Fig. 13(a)
), (b).

(formed in the order of (c)) or the angular deviation θ2 of the rotation axis of the photosensitive drum (formed in the order of (a), (b), and (c) in Fig. 14), and the deviation due to the magnification error in Fig. 12 (d). In the case of , this is due to the deviation 2×δS in the scanning line length due to the error ΔL in the optical path length from the optical scanning optical system of each image forming station to the photosensitive drum (FIGS. 15 and 16).

Therefore, in order to eliminate the above four types of deviations, we electrically adjust the timing of light beam scanning for the top margin and left margin to correct the deviations, and to correct the deviations due to the tilt deviation and magnification error. When the optical scanning means and the photosensitive drum are assembled into the apparatus, the mounting positions and mounting positions are carefully adjusted so that there is no deviation in angle.

In other words, the tilt deviation and the magnification error, which vary depending on the mounting position and angle between the optical scanning means (scanner, etc.) and the photosensitive drum, can be calculated by adjusting the angle between the optical scanning means (scanner), the photosensitive drum, or the reflecting mirror in the light beam optical path. Adjustments were made by changing the mounting position and angle.

[Problem to be solved]

However, in such conventional examples, the electrically adjustable top margin and left margin are almost completely (
However, it is difficult to adjust the tilt deviation and magnification error due to adjustment of the mounting position of the optical scanning means (scanner), the photosensitive drum, or the reflecting mirror in the optical beam path, and it is difficult and requires a lot of effort. There was a problem that it was a thing.

Another extremely important issue is the stability of image positional shift.

In other words, the position may vary due to minute fluctuations due to the running stability of the transfer belt as a moving body (meandering 5 deviation), position repeatability when attaching and detaching the photosensitive drum, and instability of the top margin and left margin in the case of laser beam printers. Misalignment occurs, which greatly affects image quality.

Additionally, the relationship between the main unit, optical system, photosensitive drum, etc., which has been adjusted once when the main unit is installed, may require complicated and difficult readjustments due to slight distortions that may occur when moving the main unit to another floor, for example. Put it away.

In addition, in a device that performs image formation with a high degree of precision that is incomparable to conventional electrophotographic devices, there is a risk of positional displacement due to thermal expansion and thermal contraction of the main body frame due to the ambient temperature.
Misalignment due to changes over time was also a major problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and its purpose is to detect positional deviation in a multiplex image forming apparatus having a plurality of image carriers. It is an object of the present invention to provide a multiplex image forming apparatus that can form stable images without positional deviation by correcting image formation based on the results.

[Means for Solving the Problems 1 Effect] In order to achieve the above object, the multiple image forming apparatus according to the present invention includes image forming means for forming different images on a plurality of image carriers;
A transfer means for transferring the images on the plurality of image carriers onto the same transfer material, a conveying means for conveying the transfer material, and a mark for positioning each image to be formed on the plurality of image carriers. A control means for controlling the image forming means, a detection means for detecting the recording position of the mark, and a positional deviation of each image in the direction of movement of the transfer material and a direction perpendicular to the direction of movement based on the detection output of the detection means. It consists of a correction means for correcting at least two of positional deviation, image magnification, and image inclination, and obtains high-quality multiple images.

[Example 1] The present invention will be explained below based on the illustrated embodiment. 1st
The figure is a configuration diagram showing a four-drum full-power image forming apparatus according to an embodiment, and in the same figure, IC, LM, IY, IB
K is a photosensitive drum in each image forming station, which is provided with developers (toner) of cyan, magenta, yellow, and black colors, respectively. These photosensitive drum ICs,
1M, IY.

The IBK rotates in the direction of the arrow in the figure, and around the photosensitive drums IC, LM, IY, and IBK, there is a primary charger for uniform charging, and a scanning device as an image writing means (latent image forming means). Optical device 3C.

3M, 3Y, 3BK, a developing device that visualizes the latent image with toner, a cleaner, and a transfer charger are respectively provided.

Further, the transfer material S is supported on a transfer bell (6a) and conveyed in the direction of arrow A, and at each of the image forming stations, toner images of each color are sequentially transferred to form a color image,
After this transfer process is completed, the image is fixed by a fixing device 8 and discharged onto a tray 9.

On the other hand, on the transfer belt 6a, apart from the image formed on the transfer material S, image register marks 34 and 35 for detecting the image position are formed by an electrophotographic process.
They are formed at regular intervals for each color. In this embodiment, a cross-shaped register mark as shown in the figure is used. Further, 14 and 15 are sensors for reading these register marks, and COD is usually used.

A COD is a linear sensor that converts an optical signal into an electrical signal, and is similar to a well-known image reading sensor that is commonly used in facsimiles and the like. Transfer belt 6
Register mark 34 formed on a. 35 is a ramp 16 located downstream of the final station.
17. Condensing lens 18. CCD14,1 through 19
5, color misregistration is read 1, and correction is performed by feedback control, which will be described later.

The scanning optical devices 3C, 3M, 3Y, and 3BK, as shown in FIG. The light beam L emitted from the light source 22 is reflected and scanned by the polygon mirror 21, passes through the fθ lens 20, and is emitted from the opening 23a of the optical box 23. On the other hand, above the optical box 23, a reflector 24 as a light reflecting means is provided with a first reflecting mirror 24a and a second reflecting mirror 24b facing each other at a substantially right angle.
The reflecting mirror 24a is fixed to the device main body (not shown) so as to be located above the opening 23a, and the light beam L emitted from the optical box 23 passes through the first reflecting mirror 24a and the second reflecting mirror 24b in order. It is configured to reach above the drum 1.

The mounting position of this reflector 24 can be adjusted independently in the directions of arrows a and 2 with respect to the main body of the device, and as an adjustment means for making these adjustments, a drive source that moves linearly in stages is used. An actuator 27, 2 such as a linear step actuator equipped with a step motor that is
8.29 is equipped.

What is the linear step actuator used here?
It is a stepping motor that causes the output shaft of the stepping motor to move linearly, and has a trapezoidal screw structure inside the motor rotor and the output shaft, and is often used mainly for moving the head of floppy disks and the like. In addition, as a similar method, the same actuator function can be achieved by using a lead screw shaft (threaded shaft) as the shaft of a stepping motor, and using a movable member with threads formed on it. .

For example, the thread formed on the lead screw is 4P0.
5 (nominal diameter 4 mm, pitch 0, 5 mm
), if the step angle of the stepping motor is 48 steps/one revolution, then the advance amount S of the output section is S = 0.
．． The feed amount can be controlled with an accuracy of 5/48=10.42 μm/step.

In this specification, these will also be referred to as actuators. Here, by driving the actuator 27 in the a1 direction, which is the emission direction of the light beam L from the scanning optical device, the reflector 24 is moved approximately in parallel in the a direction,
The optical path length can be lengthened (adjusted) by shortening the optical path length up to the photosensitive drum 1 and driving the actuator 27 in the a2 direction.

By adjusting the optical path length in this way, the length of the scanning line on the photosensitive drum of the light beam L having a predetermined spread angle can be changed to m(, for example, as shown in FIG. 3(a)).

It can be changed from ml to ml.

Further, by simultaneously driving the actuators 28 and 29 in the same direction, for example, in the b1 direction, the reflector 24 is
The scan line m in FIG.

can be translated in parallel to the position of scanning line m2.

Furthermore, if either one of the actuators 28 and 29 is moved, or if the actuators 28 and 29 are driven in opposite directions, such as driving in the b1 direction and actuator 29 in the b2 direction, as shown in FIG. 3(C). scanning line m. The inclination angle can be changed like scanning line m3.

As described above, the reflector 24 incorporating a pair of reflecting mirrors at a substantially right angle is disposed in the optical beam path from the scanning optical device to the photosensitive drum, and the position of the reflector 24 is adjusted to the position of the actuator 2.
7 or actuators 28, 29, the optical path length or the light beam scanning position can be adjusted independently.

That is, by moving the reflector 24 having a pair of reflecting mirrors arranged in a V-shape in the direction a, the light beam L can be adjusted without changing the position of the scanning line imaged on the photosensitive drum. Only the optical path length can be corrected, and the reflector 2
4 in the b direction, the image formation position and angle on the photosensitive drum can be corrected without changing the optical path length of the light beam L.

In this embodiment, a 4-drum color printer includes the above reflector,
The reflector position adjustment means is provided, and each image forming means independently corrects the inclination of the scanning line on the photosensitive drum, the magnification error based on the optical path length, the top margin, and the left margin, and sequentially adjusts the transfer material SJ. This is to eliminate color misregistration between each toner that is transferred.

Above, the actual register mark reading method and feedback method will be explained in detail using a cyan image as an example.

FIG. 4 shows a block diagram of a part that detects a register mark and performs feedback control to each station after detection.

FIG. 4 shows an example of reading a register mark written in a state where the above-mentioned scanning line inclination and magnification error occur.

Sensor 14゜15 to read register mark 34.35
is CCDI,2. Since the output of CCDI, 2 converted into an electric signal is at a very low signal level, it is amplified by each amplifier A, and then converted into an electric signal CCDIP corresponding to the exact position of the register mark by the binarization circuits 50 and 51.

Obtain CCD2P. CCDI, 2 are standards 1 and 2 respectively
When the register mark starts writing accurately and is formed at a regular position with no scanning line inclination or magnification error from the reference position, the center of the mark will be CCDI, pixel 2. The position is such that the center pixel of the image is read. Also, each CCD
The main scanning start position (left margin) is also based on standard 1. The direction of CCDI and 2 is also set to start from 2.

Figure 5 shows examples of cases where magnification errors and left margin deviations occur, and cases where normal writing is performed on the CCD.
An example will be shown along with the positional relationship of I and 2.

In the figure, the output is when IA is written at the normal position, but IB is deviated.

IA the register marks 34 and 35 on both sides.

3A and 3B show the output waveforms after binary conversion of CCDI and 2 when reading from IB after writing. The 3A output obtained by IA is CCDI because it is in the normal position.

The output No. 2 is obtained as an image signal of a register mark at a time position to from the main scanning start position (hereinafter referred to as CDHSYNC). However, as shown in 3B, register marks written at shifted positions, such as IB, are
The register mark image signal is obtained on the 1 side at the regular position, and on the C0D2 side at the time t2, which is inside the regular position and shorter than to. Therefore, like this 10>12
In such cases, the magnification is small, and if you try to adjust the magnification normally, the left margin will also change from the reference position 2A to 2B.
It can be predicted that the position will shift to .

In FIG. 4, the detection method and correction method for the magnification error and the left margin shift amount will be described in more detail with reference to the timing chart in FIG. 6.

CDH3YNC generator 7 for CCDI and CCD2
It is possible to give the main scanning period signal CDH8YNC from 0 to 1 and convert it into an image signal with this period.

Register marks 34 and 35 with CCDI and CCD2 with C
The signal outputs obtained by reading DH5YNC in this order are CCDIP and CCD2P in FIG.

At the time of (2) CDH5YNC, neither cCD has read the register mark yet, so no image signal can be obtained. Next, at the CDH5YNC cycle of ■, CC
As an output on the D1 side, a CCDIP image signal is obtained at the position t. 1. As described in the example of FIG. 5, the time of is equal to the time of to at the predetermined position.

Furthermore, at the time of the CDH8YNC cycle of ■, the CCD
2, a C0D2P image signal is obtained at the position t2. As mentioned in the example of FIG. 5, this is shorter than to. The counters that measure the tl and to times are counter 2 (62) and counter 3 (63), respectively.
). Each counter 62°63d is CLO
There is a CK terminal, and input terminal 1: XI CLOCK. Since the CLOCK frequency of Xl is used to check the amount of deviation, a higher frequency is more advantageous. 5TA of counter 1 (54), counter 2 (62)
The RT signal terminal is connected to the C of the CDH5YNC generator 70.
The DH3YNC signal is input. Also, the 5 TOP
The output signal of CCDIP is input to the counter 2, and the output signal of C0D2P is input to the counter 3, respectively, to the signal terminals. Therefore, at counter 2, CDH3YNC
Start counting the clock frequency of Xi, and C0D
It stops when the IP image signal is input, and the count number is output t.
It can be obtained as an engineering job. Also, at counter 3, CDH3YN
Start counting the clock frequency of Xl from C, and
It stops when the D2P image signal is input, and the count number is obtained as the output t2. The obtained values of 1, , 12 are compared with the value of the center value t0 by comparators CPI and CP2, and the difference Δt1. As △t2, △11=0゜△t2=
The value will be -1. In accordance with each value of △t, select the optimal movement control value of the magnification error control actuator 27, which is the first control amount in the ROM 2 in which the magnification movement amount and left margin movement amount are set in advance. Output. Furthermore, the movement amount of the left margin, which is the second control amount, is also selected and output as DE[, AY (CH).

Therefore, by this correction, the magnification error and left margin shift can be corrected by moving them to their normal positions. Following these example operations, magenta, yellow,
By repeating this for the black register marks, all stations are corrected. counter 2,
The station select signal to the E terminal of ROM 3 and the S terminal of ROM 2 is for this selection.

Next, correction of the scanning line tilt amount will be described.

When C0DIP is obtained by reading the register mark 34 when CCD1 is CDHSYNC of ■, the CDHSYNC signal is erased by EXI's exclusive OR to obtain the 5TARTI signal. This signal is counted as 5 of counter 1.
By inputting it to the TART signal terminal, counting of the CDH5YNC signal inputted to the CLOCK terminal is started. Next, the register mark 35 is read by the CCD 2 at the time of CDHSYNC of ①, and since it becomes a signal of C0D2P, the 5TOP2 signal is obtained by the EX2 in the same manner as above. By inputting this signal to the 5TOP terminal of counter 1, counting of DCH3YNC is stopped. Therefore, the value of CDl5YNC, that is, the scanning line inclination amount N, is obtained as the output of the counter l, and in this example, N=1. In accordance with this amount of deviation, the control value of the actuator 28°29 that moves the scanning line in the designated direction is adjusted to a preset R.
Select from OMI, specify station using selector, and move actuators 28 and 29. Therefore,
Through this correction, the scanning line inclination amount is corrected and the scanning line is moved to the normal position. By repeating this operation for the subsequent magenta, yellow, and black register marks, all stations are corrected. counter 1
The station select signal to the E terminal of is for that selection.

Next, correction of the top margin shift will be described.

The VSYNC-C counter detects the position of the first register mark written by the first station, and the timing signal for writing the register mark is 5TAR.
CD inserted into the CLK terminal by inputting it to the T terminal
Start counting HSYNC. This signal is CDHSY
The resolution is not limited to NC, and the resolution can be further improved by using a completely different higher frequency. Then, the register mark 5T read by CCDI first.
By stopping with the ART signal, the count of CD15YNC is stopped. This value C' is compared with the value obtained when writing a register mark at a predetermined position, and is led to ROM3, which selects and outputs the difference amount.
(7) Output j: DELAY (CV) (7)) "7B margin control output is obtained. Therefore, this correction corrects the top margin shift and moves it to the normal position. .

All stations are corrected by repeating for the yellow and black register marks. Note that since the register marks are successive in the operation of each VSYNC counter, it goes without saying that a control signal is required, although not shown, so as not to stop at a register mark signal at an unnecessary position. Furthermore, the top margin shift can be corrected in the same way by using the control value selected from the ROM 3 as the control value for the actuators 28 and 29.

By combining the operations described above, images with various color shifts can be corrected automatically and quickly.

In addition, the register marks formed on the transfer belt are
After passing through the CCD reading section, the belt is cleaned by a belt cleaning device, such as the cleaning blade 7 shown in FIG. 1, in preparation for writing the next register mark.

[Embodiment 2] FIG. 7 shows a second embodiment of the present invention. In this embodiment, the optical box 23 (fθ
Lens 20. The polygon mirror 21 (a box in which the laser light source 22 is integrated) is provided so that its mounting position can be corrected by a position moving means that is adjustable with respect to the main body of the apparatus. The mechanism will be described below.

In FIG. 7, reference numerals 40 and 41 are stepping motors or actuators such as the linear step actuator described in the first embodiment.

Here, by driving the actuator 40 in the direction a, which is the emission direction of the light beam L from the scanning optical device,
The optical box 23 is configured to be moved substantially parallel to the direction a along the axis l. Thereby, by shortening the optical path length up to the photosensitive drum 1 and driving the actuator 40 in the a2 direction, the optical path length can be adjusted to be longer. In this way, similarly to the first embodiment, magnification errors can be corrected.

Furthermore, by driving the actuator 41, the optical box 23 is moved around the axis l as the rotation center, and thereby,
The amount of inclination of the scanning line can be adjusted.

As described above, the amount of color shift described above can also be corrected by correcting the position of the scanning optical device itself. Read the register marks below this and register these actuators 40. Feedback control of the amount of correction to 41,
The reading method etc. are all the same as the method described in the first embodiment.

[Embodiment 3] FIG. 8 shows a third embodiment of the present invention. This embodiment is configured so that the scanning line inclination, magnification error, etc. due to color misregistration described above can be corrected by means for moving the position of the image carrier (that is, the photosensitive drum). The mechanism will be explained below.

In FIG. 8(a), IOC, IOM, IOY,
10BK is a flange fixed to both ends of the photosensitive drums IC, IM, IY, IBK, and each of the flanges is attached to a shaft supporting device 11C, IIM, IIY, I shown in FIG. 8(b).
Pivotally supported by IBK, the pivot device 11c, II
M, IIY.

11BK is fixed to a support member corresponding to each photosensitive drum. Further, the photosensitive drum is driven by a drive transmission mechanism (not shown).

8(b) and 8(C) are detailed views of the pivot device 11. In this figure, the shaft 10a of each flange 10 is supported by a bearing 601. The bearing 601 is supported by an inner case 604 so as to be movable in the direction of arrow A by a guide groove (not shown), and is biased by a spring 602 by an actuator 603. In addition, the inner case 60
4 is also supported by an outer case 607 by a guide groove (not shown) so as to be movable in the direction of arrow B, which is perpendicular to arrow A, and is biased by a spring 605 by an actuator 606. Note that the actuator 603 in this case
, 606 are preferably linear step actuators as explained in the previous embodiment.

For example, as shown in FIG. 8(a), this pivot device 11 is
When installed with the A direction aligned with the horizontal direction and the B direction aligned with the vertical direction, the front and rear actuators 606a,
When the photosensitive drums 606b are simultaneously driven in the same direction, that is, in the B direction, the photosensitive drum l is moved substantially parallel to the direction in which the light beam L is emitted from the scanning optical device, and the optical path length changes. This allows correction of magnification errors.

Moreover, when either one of the actuators 603a and 603b is moved, or the actuator 603a.

By driving 603b in opposite directions,
The amount of scanning line inclination can be corrected.

Furthermore, if the actuators 603a and 603b are simultaneously driven in the same direction, this is the same as moving the scanning line in parallel, that is, it is also possible to adjust the top margin.

As described above, the above-mentioned amount of color misregistration can also be corrected by correcting the position of the photosensitive drum itself. Feedback control of correction amounts to these actuators 603 and 606 by reading register marks below this,
The reading method etc. are all the same as the method described in the first embodiment.

The method described above can also be applied to other image forming apparatuses, such as the image forming apparatus shown in FIG. 9 equipped with the intermediate transfer member 10 and the image forming apparatus shown in FIG. 10 using roll paper 11 as a transfer material. can. In the case of FIG. 9, the register mark is the intermediate transfer body 1
0 or on the transfer material S, and in the case of FIG. 10, it is formed on the roll paper 11.

Further, the present invention is applicable not only to a four-drum color printer, but also to, for example, a two-color or three-color multicolor image forming apparatus or a multiplex image forming apparatus.

Furthermore, in the first embodiment, a case has been described in which a reflector equipped with a V-shaped reflecting mirror is used as the optical system that defines the optical path of the light beam L, but the invention is not limited to this. When mounting the reflecting mirrors, the position, angle, and number of reflecting mirrors may be freely selected, or a pair of reflecting mirrors may be integrally formed in an L-shape.

In addition, in each embodiment, a linear step actuator was used as an example of the actuator, but other actuators with similar functions such as a threaded shaft of a normal stepping motor, gum, and a linear motor may also be used. Anything that fulfills this purpose is fine.

Further, the position of the register mark to be formed may be any position on the moving object as long as it can be formed by electrophotography, and the shape of the register mark may also be
The shape is not limited to the one used in this embodiment, but any shape may be used as long as it is possible to detect the image shift as described above.

Further, as described above, cleaning the belt after register marks are written is more effective by using a fur brush method or an air suction method in addition to the cleaning blade method.

Furthermore, as for the number of sensors such as CCDs used for reading, in the present invention, images are read at two places, one on the front side and the other on the back side, but if this number is increased to, for example, three or four places, It goes without saying that it is possible to read image shifts with even higher precision.

〔Effect of the invention〕

The present invention has the above-described configuration and operation, and by having a detection means for detecting a mark for detecting positional deviation and a correction means for correcting a plurality of positional deviation elements based on the detection means, the present invention can be applied to a transfer material very easily. It is possible to eliminate positional deviations between a plurality of images, and as a result, it is possible to form an image of extremely high quality.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a first embodiment of an image forming apparatus according to the present invention, FIG. 2 is a perspective view of essential parts of the first embodiment, and FIGS. 3(a), (b), and (c) are FIG. 4 is a block diagram showing the feedback control of this embodiment. FIG. 5 is an illustration of the COD reading unit. FIG. 6 is a timing diagram showing the feedback control of this embodiment. Chart, FIG. 7(a) is a perspective view of the second embodiment, FIG. 7(b) is a perspective view of the main part of the second embodiment, and FIG. 8(a) is a perspective view of the second embodiment.
) is a perspective view of the third embodiment, FIG. 8(b) is a perspective view of the main part of the third embodiment, and FIG. 8(c) is a perspective view of the third embodiment.
) is a sectional view of the main part of the third embodiment, FIGS. 9 to 11 are other embodiments, and FIGS. 12(a), (b), (C), (d)
' are explanatory diagrams showing image displacement, respectively; Figures 13(a), (b), and (C) are explanatory diagrams of image displacement due to positional displacement of the optical scanning device; Figures 14(a), (b), (C) is an explanatory diagram of image shift due to misalignment of the axis of the photosensitive drum, FIG. 15 is an explanatory diagram of optical path length error, and FIG. 16 is an explanatory diagram of magnification error due to optical path length error. CD) (b)
ζC) C2 , B - m1 square ゝ Yuyu 11117
-A

Claims (7)

[Claims] (1) An image forming unit that forms different images on a plurality of image carriers, a transfer unit that transfers the images on the plurality of image carriers onto the same transfer material, a transport unit that transports the transfer material, and A control means for controlling the image forming means to form marks for alignment of each image on a plurality of image carriers, a detecting means for detecting the recording position of the mark, and a detecting means based on the detection output of the detecting means. 1. A multiplex image forming apparatus comprising a correction means for correcting a plurality of positional deviation elements between each image. (2) The multiple image forming apparatus according to claim 1, wherein the detection means detects the mark transferred onto a conveyor belt constituting the conveyor means. (3) The multiple image forming apparatus according to claim 1, wherein the detection means detects the mark transferred onto the transfer material. (4) The multiple image forming apparatus according to claim 1, wherein one of the plurality of misalignment factors is misalignment of the transfer material in the conveyance direction. (5) The multiple image forming apparatus according to claim 1, wherein one of the plurality of misalignment elements is misalignment in a direction approximately perpendicular to the conveying direction of the transfer material. (6) The multiple image forming apparatus according to claim 1, wherein one of the plurality of misalignment elements is an image tilt. (7) The multiplex image forming apparatus according to claim 1, wherein one of the plurality of misalignment elements is an image magnification.