JPH01250970A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent color slippage by limiting correction processing to each image carrier based on color used information, performing correcting only the image carrier corresponding to used color, stopping the correction to the image carrier corresponding to unused color, and stopping the overall correction to the image carrier when the used color information specifies monochrome usage. CONSTITUTION:A controller 13 serves as a correcting means and a correction limiting means. For example, when any two specified colors out of four colors are inputted as the information, only an image on an image forming station corresponding to the information is corrected, and correction of image forming stations corresponding to unused color is stopped. When the inputted information specifies monochrome, correction is overall stopped. Thus the time for adjusting color slippage can be shortened, and simultaneously images of required color can be overlapped at high accuracy.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an image forming apparatus that forms an image by exposing an image carrier to light using an electrophotographic method, such as a laser beam copying machine or a facsimile machine. In particular, the present invention relates to an apparatus that forms multiple, multicolor, or color images by disposing a plurality of optical scanning means.

(Prior Art) Conventionally, as an image forming apparatus having a plurality of optical scanning means, for example, the one shown in FIG. 11 is known.

FIG. 11 is a schematic diagram illustrating the configuration of a four-drum full-color image forming apparatus, 101C.

101M, 101y, and 1018 are image forming stations that form images of cyan, magenta, yellow, and black, respectively, and each image forming station 1
01C, 101M, 101Y, and 1018 each have a photosensitive drum 102C.

102M, 102Y, +02BK and optical scanning means 10
3c, 103M, 103Y, 1038K, and further includes a developing device, a cleaner, etc., and is placed on the transfer material S conveyed in the direction of arrow A by the transfer heald 112 (described later in FIG.
A color image is formed by sequentially transferring cyan, magenta, yellow, and black images 104c, 104M, 104Y, and 104BK. In this way, a plurality of image forming stations 101c, IOIM, 101Y,
In an apparatus having 1018K, each image forming station 1oic, 104M, 10IY, 104B sequentially transfers images of different colors onto the same surface of the same transfer material S.
If the transferred image position in K deviates from the ideal position, for example, in the case of a multi-color image, the image intervals of different colors may become misaligned or overlap, or in the case of a color image, there may be a difference in color tone, and if the degree is severe, the color may change. This caused the image quality to deteriorate significantly.

By the way, the first type of positional deviation of the transferred image is
Misalignment (top margin misalignment) of the transfer material S in the transport direction (direction in the figure) as shown in Fig. 2(a), Fig. 12(a)
Positional deviation (left margin deviation) in the scanning direction (direction B in the figure) as shown in b), tilt deviation in the diagonal direction as shown in Fig. 12(c), and as shown in Fig. 12(d). In actuality, each of the above-mentioned positional deviations does not occur individually, but a combination of these positional deviations, that is, a superposition of four types of positional deviations appears.

In the case of the top margin (see FIG. 12(a)), the main cause of the image position shift is each image forming station 101C, IOIM.

This occurs due to the difference in the timing of writing each image of 101Y and 10IBK, and the left margin (Fig. 12 (b)
), each image forming station 101c,
This occurs due to a shift in the writing timing of each image to the IOIM, 101Y, and 1018, that is, the scanning start timing for one scanning line, and the tilt shift in the diagonal direction (
(see FIG. 12(c)), the scanning optical system is attached with an angular deviation θ1 (see FIGS. 13(a) to (c)) or the photosensitive drums 102C, 102M, and 102Y.

Angular deviation θ2 of the rotation axis of 102BK (Fig. 14 (a)
-(C)), and the deviation due to magnification error (see FIG. 12(d)) is caused by the difference between each image forming station 1.
From the light scanning optical system of 01C, 101M, 101Y, 101BK to the photosensitive drums 102C, 102M, 102Y, 10
This occurs due to the error ΔL in the optical path length up to 28K, that is, due to the scanning line length deviation 2×δS (see FIGS. 15 and 16).

Therefore, in order to eliminate the above four types of deviations, the top margin and left margin are corrected by electrically adjusting the timing of light beam scanning, and the deviations due to the tilt and magnification errors are corrected by the optical scanning means. (103C
, 103M, 103Y, 1038K) and photosensitive drum 10
When attaching 2c, 102M, 102Y, and 1028 to the main body of the device, sufficient positional adjustment has been made to ensure that the positions and attachments do not shift angularly.

In other words, the mounting position of the optical scanning means (scanner, etc.) and the photosensitive drum is such that the above-mentioned tilt deviations and magnification errors, which vary depending on the mounting position and angle, are detected in the optical scanning means (scanner), the photosensitive drum, or in the light beam optical path. The installation of reflective mirrors has been adjusted by changing the position and angle.

[Problem to be solved by the invention]

However, deviations due to the above-mentioned top margin, left margin, and tilt 1 magnification errors that occur as the image forming apparatus changes over time are caused by electrical or optical scanning means (
scanner), photosensitive drum.

Alternatively, correction is performed by adjusting reflective mirrors, etc., but for example, during the adjustment process before the start of the normal image forming sequence, registration marks for positional deviation detection are transferred to the conveying body to be conveyed. Irradiation of a light beam to each remaining image bearing member based on the relative difference between the detection timing of a predetermined one registration mark image among the plurality of registration mark images and the detection timing of each remaining registration mark image for each transferred image bearing member. Color shift is corrected by individually correcting the starting position, the angle of light beam irradiation to each remaining image carrier, and the optical path length of the light beam to each remaining image carrier. Therefore, there is a problem in that the time required for this adjustment process becomes long.

This problem is especially serious in the case of monochrome one-color, two-color, three-color copying, etc., that is, when unused colors are generated. , there are useless operations such as reading,
As a result, the time required for color misregistration adjustment during monochrome copying is about the same as that for full color copying, which significantly impairs printing processing efficiency and reduces the lifespan of each process component, including the image carrier, which is originally unused. There are serious problems such as shortening the lifespan.

The present invention was made to solve the above problems, and in a multi-image forming apparatus having a plurality of image carriers, the color misregistration adjustment process is limited to the colors to be used. To obtain an image forming apparatus that can form optimal color images without positional deviation at all times while greatly shortening the adjustment processing time for color and i-color and greatly extending the life of image forming parts that are not used for development. The purpose is to

[Means to solve the problem]

The image forming apparatus according to the present invention detects a predetermined one registration mark image detection timing among a plurality of registration mark images for each image bearing member transferred to a conveying member sequentially by a detection means, and detects each remaining registration mark image. The light beam irradiation start position on each remaining image carrier and the irradiation angle of the light beam on each remaining image carrier based on the relative difference with the timing.

A correction means for individually correcting the optical path length of the light beam to each of the remaining image carriers, and a correction processing restriction means for restricting execution of correction processing by the correction means to each image carrier based on the input color information to be used. It was established.

[Effect]

In this invention, when the color information to be used is input, the correction processing limiting means limits execution of the correction processing to each image carrier by the correction means based on the color information to be used, and images corresponding to the color to be used are Executes only the correction process on the image carrier, suspends the correction process on the image carrier corresponding to unused colors, and stops all correction processes on the image carrier, especially when the color information to be used specifies a single color. do.

〔Example〕

FIG. 1 is a perspective view illustrating the configuration of a four-drum full-power single-type image forming apparatus showing an embodiment of the present invention;
C, IM, IY, and IBK are photosensitive drums, and are cyan, magenta, and yellow, respectively.

One is provided for each image forming station provided with a developer (toner) for each color of black. 2C.

2M, 2Y, 28 are scanning mirrors, and optical scanning systems 3C13M, 3Y, 3 are provided for each image forming station.
The light emitted from 8K is transmitted to each photosensitive drum IC, IM, IY.
, to form an image on IBK. 4 is a conveyor belt serving as a conveyor, and each photosensitive drum IC.

Registration marks 11 and 12 for each color formed with 1M, IY, and IBK are transferred. Registration mark 11.12
are transferred in parallel on a straight line orthogonal to the conveyance direction of the conveyor belt 4. Photosensitive drums 1C11M, IY, IBK, and scanning mirror 2C that constitute each image forming station
, 2M, 2Y, 28, optical scanning systems 3C, 3M, 3Y,
38 can be moved in a predetermined direction by an actuator mechanism which will be described later.

Reference numeral 5.6 denotes a mark detector composed of a charge imaging device such as a COD, and the mark detector 5 receives reflected light from the lamp 7 exposed to the conveyor belt 4 via a condenser lens 9. , outputs image data of the registration marks 11 detected in synchronization with the detection timing signal output from the controller 13 (each registration mark 11 is composed of, for example, four raw mark images) to the controller 13, and performs mark detection. The device 6 receives the reflected light from the lamp 7 exposed to the conveyor belt 4 via the condensing lens 10.
Image data of the registration marks 12 (each registration mark 12 is composed of, for example, four green mark images) detected in synchronization with a detection timing signal output from the controller 13 is output to the controller 13.

A cleaner member 8 collects toner images corresponding to the registration marks 11 and 12 transferred to the conveyor belt 4.

Note that the controller 13 also serves as a correction means and a correction processing restriction means of the present invention. For example, when full color mode is specified as the color information to be used by an external controller (not shown) or a color specification key provided on the main body of the image forming apparatus, The mark detection timing detected in the registration mark image of the cyan image forming station output from the mark detector 5.6 and the sequential mark detector 5.6#
), the optical scanning system 3
Light beams are emitted from M, 3Y, and 38K from each photosensitive drum 1M, +Y.

By individually adjusting the optical path length, scanning length, and scanning direction (with respect to the axial direction of photosensitive tram IM, IY, and IBK) for IBK in image forming stations other than cyan, all image formation is possible. Forcibly adjust the positional deviation at the station to the positional deviation state for cyan.

On the other hand, if any two of the above four colors are specified and input as the color information to be used, the above correction process is executed only to the image forming station corresponding to the color information to be used, and the remaining unused colors are The correction processing for the image forming station corresponding to is suspended. In this case, especially if the input color information to be used specifies a single color, the above correction process is completely suspended.

For example, if two-color copying of cyan and magenta is specified, the mark detection timing detected in the registration mark image data of the image forming station for cyan, which is the reference color output from the mark detector 5.6, Depending on the difference between the detection timing of the registration mark image data formed at the subsequent magenta image forming station detected by the mark detector 5.6, that is, the image shift state of the cyan image forming station is prioritized. In this case, the optical path length, scanning length, and scanning direction (with respect to the axial direction of the photosensitive drum 1M) of the light beam L emitted from the magenta optical scanning system 3M with respect to the photosensitive drum 1M are controlled by an actuator provided at the magenta image forming station. By adjusting the drive, the positional deviation at the magenta image forming station is forcibly adjusted to the positional deviation state for cyan, which is the reference color. At this time, writing and reading of registration marks in the unused image forming stations, yellow and black image forming stations, and driving of actuators are stopped, and they are not involved in the positional deviation adjustment process. In this manner, in the case of two-color mode based on the color information to be used, positional deviation adjustment processing is executed only for the two image forming stations for magenta and cyan.

FIG. 2 is a perspective view illustrating the arrangement of the scanning mirror and the optical front thread shown in FIG. 1, and the same parts as in FIG. 1 are given the same reference numerals.

Note that the same configuration as this is provided for each image forming station, and the case of the cyan station is particularly shown.

In this figure, 20 is an fθ lens, and a laser light source 22
A polygon mirror 21 that is fired from and rotates at a constant speed.
The laser beam (light beam) L deflected by the laser beam L is imaged, for example, on the photosensitive drum 1C at a constant speed. 23 is an optical box which integrally accommodates the above-mentioned 20 to 22. Note that the laser beam emitted from the laser light source 22 is emitted from the aperture 23a via the fθ lens 20. Reference numeral 24a designates a first reflective mirror, and a second reflective mirror 24b provided substantially perpendicularly to the first reflective mirror 24a allows the reflectors 24 corresponding to the scanning mirrors 2M, 2Y, and 28K shown in FIG. configured.

Note that the laser beam emitted from the laser light source 22 is configured to form an image on, for example, the photosensitive drums 1M, 1Y, and IBK via a first reflecting mirror 24a and a second reflecting mirror 24b.

Reference numeral 25 denotes a linear step actuator (actuator) composed of, for example, a stepping motor, and a reflector 24 in which a first reflecting mirror 24a and a second reflecting mirror 24b are integrally supported according to the step amount output from the controller 13 is shown in the figure. vertically up and down in the a direction.

Reference numeral 26 and 27 are linear step actuators (actuators) composed of, for example, stepping motors, and the reflector 24 integrally supports the first reflecting mirror 24a and the second reflecting mirror 24b according to the step amount output from the controller 13. are independently horizontally moved in the b direction in the figure. In addition, the above linear step actuator 2
5 to 27 move the output shaft of a stepping motor linearly, and the structure is such that a trapezoidal screw is formed inside the motor rotor and the output shaft, and is usually used mainly for moving the head of floppy disks etc. It is suitable for what is there. In place of the linear step actuators 25 to 27, a movable member may be used in which a lead screw (threaded shaft) is formed on the shaft of a normal stepping motor, and a thread corresponding to the lead screw is formed on the shaft of a normal stepping motor. It is possible to function in the same way using . Specifically, when the screw formed in the lead screw is 4PO05 (nominal diameter 4 mm, pitch 0.5 mm) and the step angle of the stepping motor is 48 steps/one revolution, the advance amount SS of the output section is 5S. =0.5/
48=10.42μm/step, and this 10.4
The reflector 24 can be driven and controlled at a feed rate of 2 μm/step.

Next, the driving operation of the actuators 25 to 27 shown in FIG. 2 will be explained with reference to FIGS. 3(a) to 3(C).

FIGS. 3(a) to 3(c) are schematic diagrams illustrating image shift on the image carrier, where S indicates a transfer material, and this transfer material S is conveyed in the six directions of arrows (the conveyance direction of the conveyor belt 4). be done.

Here, by driving the actuator 25 in the a1 direction (shown in FIG. 2), which is the emission direction of the light beam L from the scanning optical device, the reflector 24 is moved approximately parallel to the a direction, and the photosensitive drum 1c By shortening the optical path length up to the top and driving the actuator 25 in 82 directions, the optical path length can be adjusted to be longer. In this way, by adjusting the optical path length, the length of the scanning line on the photosensitive drum 1C of the light beam L having a predetermined spread angle can be adjusted as shown in FIG.
) as shown in m. (solid line) to mi (broken line).

Furthermore, by simultaneously driving the actuators 26 and 27 in the same direction, for example, in the b1 direction, the reflector 24 is moved in parallel in the a and b directions, which are substantially perpendicular to the force direction.
As a result, scanning line m0 in FIG. 3(b) is changed to scanning line m2 (
It can be moved in parallel to the position indicated by the broken line).

Furthermore, when either one of the actuators 26 and 27 is driven, or when the actuators 26 and 27 are driven in opposite directions, such as driving the actuator 26 in the b1 direction and the actuator 27 in the b2 direction, as shown in FIG. ) can have a variable slope like scanning line m3 (broken line).

In this way, the reflector 24, which has a pair of reflecting mirrors installed at approximately right angles, is disposed in the optical beam path from the scanning optical device to the photosensitive drum 1C, and the position of the reflector 24 is adjusted by the actuator 25.
Alternatively, the optical path length or the light beam scanning position can be adjusted independently by adjusting the actuators 26 and 27. In other words, by moving the reflector 24 having a pair of mirrors arranged in the shape of a square in the direction a, the light beam L can be adjusted without changing the position of the scanning line imaged on the photosensitive drum 1C. Only the optical path length can be corrected, and the imaging position and angle on the photosensitive drum 1C can be corrected without changing the optical path length of the light beam L by moving the reflector 24 in the direction b. Can be done.

In this embodiment, a four-drum full-color printer is provided with the reflector 24 and an actuator mechanism for adjusting the position of the reflector 24, respectively.
A photosensitive drum IC, IM is provided independently for each image carrier serving as each image forming means.

In 1Y and 18K, the magnification error based on the inclination of the scanning line and the difference in optical path length, the top margin, and the left margin are individually corrected to eliminate color misregistration between the toners of each color sequentially transferred to the transfer material S. has been done.

The reading operation of the registration marks 11 and 12 for color misregistration detection and the color misregistration correction feedback control operation executed based on this reading will be described below in sequence without reference to FIG. 4.

FIG. 4 is a control block diagram illustrating the internal configuration of the controller 13 shown in FIG. 1, and the same components as in FIG. 1 are given the same reference numerals.

In this figure, 318 is an amplifier that amplifies the mark image signal output from the mark detector 5. A binarization circuit 32a outputs image data CC02P obtained by converting the analog signal output from the amplifier 31a into digital data to the exclusive logic gate 35b and the third counter circuit 42.

32b is a binarization circuit that converts the analog signal output from the amplifier 31b into digital data, which is the image data C.
0DIP is output to exclusive logic gate 35a and second counter circuit 39. 33 is a clock generator,
Generates one main scanning period signal CDH3YNC, outputs this one main scanning period signal CDH3YNC as a reading synchronization signal for mark detectors 5 and 6, and outputs it to clock input CLK to VSYNC counters 37C, 37M, 37Y, and 378. . Note that, for example, the mark detectors 5 and 6
are placed at preset positions corresponding to standards 1 and 2, respectively, and registration marks 11 and 12 are accurately written starting from the reference position. The center of the registration mark 11, 12 is precisely adjusted to a position where it can be read by the center pixel of the pixels of the mark detectors 5, 6 when the registration mark 11, 12 is formed at a normal position. That is, in order to be able to read the center of the registration mark image formed by the first image forming station (cyan), which is the reference station, with the center element of the mark detector 5.6, the cyan image is formed at an early stage. The position of the reflector 24 of the station or the optical scanning system 3C is controlled by driving actuators 25-27. This drive control makes it possible to always detect the center of the registration mark image developed and transferred with cyan toner, which is the reference color, using the center pixel of the mark detector 5.6. , accurately detects the center deviation from the registration mark image formed at the second image forming station (image forming station for magenta) that is detected next, and adjusts the image for magenta according to the amount of positional deviation detected. The actuators 25 to 27 of the forming station are driven and controlled.

34 is a first counter circuit, which receives one main scanning period signal CDH3.
Image data CCDI for the registration mark image for cyan, which is the reference color constituting the registration mark 12, detected by the mark detector 6 at the YNC sending timing ■
P is obtained, and one main scanning period signal CDH is generated in synchronization with a start signal 5TARTI which is an exclusive OR output of this image data CCDIP and one main scanning period signal CD15YNC.
Start counting 3YNC, 1 main scanning period signal CDH
Image data CCD for the registration mark image for cyan, which is the reference color constituting the registration mark 11 detected by the mark detector 5 at the time of 3YNC sending timing ■
Counting of one main scanning period signal CDH3YNC is completed in synchronization with stop signal 5TOP2 which is an exclusive OR output of 2P and one main scanning period signal CDH3YNC. The count data counted from the start to the end of this count is the scanning line inclination amount N of the reference color cyan. obtained by binding,
This scanning line inclination amount N. That is, using the tilt amount of the reference color cyan as a reference value, the image shift amount is calculated by comparing the scan line tilt amount NM corresponding to the second image forming station (image forming station for magenta) which is sequentially detected. The image shift amount for the second image forming station is output as a selection signal to the first ROM 35 (in which control values for moving each actuator 26, 27 of the M2 image forming station in a designated direction are stored). Ru. Note that the first counter circuit 34 is enabled based on an image forming station select signal output from a CPU (not shown).

36 is a selector circuit, and each control value ADM, ADY, ADBK read from the first ROM 35 is outputted to an actuator 26, 27 that drives the reflector 24 of the second image forming station (image forming station for magenta). Ru.

37C is a VSYNC counter, which receives a registration mark write signal output at the timing when a cyan registration mark (a cyan registration mark image serving as a reference color constituting registration marks 11 and 12) is written at the first image station. Synchronized with one main scanning period signal CDl
5YNC starts counting, and the mark detector 6 detects the registration mark image for cyan, which is the reference color constituting the registration mark 12, and outputs the image data C.
1 when the start signal 5TARTI is output from the exclusive OR gate 35a in synchronization with CD 1.
The count of the main scanning period signal CDHSYNC is finished, and the count value, that is, the top margin correction reference value CO of the reference color cyan is obtained. Then, the top margin value MO of the subsequent second image forming station is obtained by the same counting process by the VSYNC counter 37M, and the top margin correction reference value co and the top margin value MO are compared, and the top margin value MO between cyan and magenta is The controller 13 calculates the amount of image shift due to margin shift. Then, according to the calculated image shift amount, the third ROM 3 in the latter stage
B (in which a control value for correcting the top margin is stored in advance) as a selection signal. 3rd RO
M38 is a delay signal DE for correcting the top margin
LAYM is output to the actuator 26,27 of each second imaging station.

39 is a second counter circuit, which receives one main scanning period signal CDHS.
YNC&: Start counting XICLOCK input synchronously, and when the mark detector 6 detects the registration mark image for cyan, which is the reference color constituting the registration mark 12, and outputs the image data ccDIP, the XIC
The LOCK count ends, the count value to+ is held in a register (not shown), and XICLOCK is input in synchronization with one main scanning period signal CDHSYNCkm.
starts counting, and when the mark detector 6 detects the registration mark image for the second image forming station (image forming station for magenta) constituting the registration mark 12 and outputs the image data CCDIP,
The ICLOCK count ends and the count value tl is output to the comparator 40 at the subsequent stage. A comparator 4o receives the count value t held in the register. 1 and the count value 1, and output the difference Δt1 to the second ROM 41 as a selection signal. The difference Δt is stored in the second ROM41.
1, optimal control values A2 to A4 for driving the actuator 25 of the second image forming station are output, respectively.

42 is a third counter circuit, which receives one main scanning period signal CDH3.
YNCk: Starts counting of XICLOCK that is input synchronously, and when the mark detector 5 detects the registration mark image for cyan, which is the reference color constituting the registration mark 11, and outputs the image data C0D2P, the XICLOCK starts counting.
LOCK count is finished, the count value to2 is held in a register (not shown), and one main scanning period signal CDHSYNCk: XICLOCK input synchronously.
starts counting XICLOCK, and when the mark detector 5 detects the registration mark image for the second image forming station constituted by the registration mark 11 and outputs the image data CCD2P, the counting of XICLOCK ends and the count value t2 is output to the comparator 43 at the subsequent stage.

The comparator 43 receives the count value t held in the register. 2 and the count value t2 counted by the third counter circuit 42, and the difference Δt2 is stored in the second ROM 4.
1 as a selection signal. The second ROM 41 contains optimal delay control values DMI and D for driving the actuators 26 and 27 of the second image forming station according to the difference Δt2.
Either output Y1 and DBKI respectively, or output the difference Δt
2, the vertical synchronization signal output timing that determines the image writing timing is adjusted.

Note that the mark detectors 5 and 6 are positioned so as to start reading in the main scanning direction from a reference 1.2 shown in FIG.

Next, the operation shown in FIG. 4 will be explained with reference to FIGS. 5 and 6.

FIG. 5 is a diagram for explaining the reading operation of the registration marks 11.12 by the mark detector 5.6 shown in FIG. 4, and the same parts as in FIG. 1 are given the same reference numerals.

In this figure, IA indicates the write output for cyan, and IB indicates the write output corresponding to the second imaging station. 3A is mark reading data, registration mark 1 formed at the cyan station, which is the reference color.
1.12 corresponds to the binary output for the write output IA for the cyan registration mark image.

3B is mark reading data, which corresponds to the binary output for the write output IB for the registration mark image formed at the second image forming station.

When the registration marks 11 and 12 transferred to predetermined positions at both ends of the conveyor belt 4 are detected by the mark detectors 5 and 6,
First, the center pixels of the image data CCD2P and CCDIP for the cyan registration mark image are each set at time t from one main scanning period signal CDH5YNC. +, to, (
Count value t. A resist image signal for cyan is obtained at a time position of 1°tQ2). However, if the writing position shifts as shown in the writing output IB for the registration mark image formed at the second image forming station,
Count value t. Even if 1 and count value t1 match, count value t. 2 and count value t2 no longer match, for example, t. At 2>t2, the mark image formed at the second image forming station becomes smaller than the reference color cyan image, and this reduction magnification error causes the comparator 40 to drive and control the actuator 25 provided at the second image forming station. A selection signal for selecting the magnification control value is output to the second ROM 41.

FIG. 6 is a timing chart explaining the operation of FIG. 4, and the same parts as in FIG. 4 are given the same reference numerals.

The magnification error and left margin shift amount detection operations will be described below.

The mark detectors 5 and 6 receive one main scanning period signal C outputted from the clock generator 33 at sending timings ■ to ■.
The cyan registration mark image corresponding to the reference color constituting the registration mark 11.12 conveyed in synchronization with DH3YNC (Fig. 4) is read, and image data CCD IP and CCD2P shown in Fig. 6 are sequentially output. However, at the sending timing (2), the mark detector 5.6 has not sold 8 of the registration marks 11.12), so the cyan image signal is not output. Then, at the sending timing ■, 1 main scanning period signal CDHSYNC to 11
At the time (equal to t.1 shown in FIG. 5), image data CCDPI is obtained by binarizing the detection signal for the cyan registration mark image constituting the registration mark 12 detected by the mark detector 6. . Then, at transmission timing (3), time t starts from one main scanning period signal CDH3YNC. Image data CCD obtained by binarizing the detection signal for the cyan registration mark image constituting the registration mark 11 detected by the mark detector 5 at time point 2.
2P is obtained.

In this way, when the image data CCDIP and CCD2P are obtained from the binarization circuits 32a and 32b, the second counter circuit 39. The counting process by the third counter circuit 42 is started as described above, and the count value t01.
t02 is temporarily saved in a register and sent to one of the comparators 40 and 43. Therefore, first, the comparator 40 receives the input count value t. 1 (based on the writing position of the reference color cyan) and a count value t1 obtained by counting the detection timing of each registration mark image formed at the second image forming station that is subsequently inputted by the second counter circuit 39. Compare the reference color difference Δ
1+ (content 0) is output to the second ROM 41 as a selection signal. In response, the second ROM 41 outputs a magnification correction control signal to each actuator 26, 27 of the second image forming station.

On the other hand, the comparator 43 receives the input count value to2.
(Writing position reference for the reference color cyan) is compared with the count value t2 obtained by counting the detection timing of each registration mark image formed at the second image forming station that is inputted next by the third counter circuit 42, and The difference Δt2 (content -1) with respect to the color is outputted to the second ROM 41 as a selection signal.

As a result, the optimum movement control values (control values A2 to A4) for driving the actuator 25 of each image forming station are output from the table in which the magnification movement amount and left margin movement amount are set, which are stored in advance in the second ROM 41. At the same time, the delay control value DMI, which is the amount of movement of the left margin, is stored in the selection boat S of the second ROM 41.
Accordingly, by this correction, the magnification error and left margin deviation of the magenta color are moved and corrected without image deviation from the cyan image which is the reference color.

Next, the correction process for the amount of scanning line inclination will be explained.

Similarly to the above, the cyan registration mark image constituting the registration mark 12 is read by the mark detector 6 in synchronization with the 1 main scanning period signal CDl5YNC sent out at the sending timing ■, and the image data is sent out from the binarization circuit 32b. When C0DIR is obtained, the subsequent exclusive OR gate 3
5a, one main scanning period signal CDH5YNC which is one input is erased, and the start signal 5TART
1 is generated, and this start signal 5TARTI is applied to the 5TART signal terminal of the first counter circuit 34 and VSYNC.
It is input to the clock input CLK of counters 37C and 37M. In response to this, the first counter circuit 34 starts counting the one main scanning period signal CD15YNC.

Next, at sending timing (3), the mark detector 5 reads the cyan registration mark image constituting the registration mark 11, and converts the image data C from the binarization circuit 32a.
Outputs 0D2P. Next, by inputting the stop signal 5TOP2 from the exclusive OR gate 35b at the subsequent stage to the 5TOP terminal of the first counter circuit 34, the counting process of one main scanning period signal CDHSYNC is stopped, and the count number counted so far is That is, the scan line tilt amount N of the reference color cyan. is obtained, and this scanning line inclination amount N. Then, by the time the stop signal 5TOP2 is inputted from the exclusive OR gate 35b corresponding to the registration mark image corresponding to the second image forming station (magenta color) detected by the mark detector 11, The scanning line tilt amount NM corresponding to the second image forming station counted by the first counter circuit 34 is compared to calculate the difference of each image shift, and the second ROM 35 (actuator 26.
7 in a designated direction is stored).

Each actuator 26, 27 of the second image forming station positions the reflector 24 at an appropriate position in accordance with this scanning line tilt correction control value. By performing this operation for the magenta registration mark image, each control value ADM is output to the actuator 26, 27 of the magenta image forming station in accordance with the station select signal input to the selector circuit 36, and the reflector 24 is positioned at an appropriate position, and the amount of scanning line inclination is corrected.

Next, a top margin shift correction process will be described.

The second image forming station (for magenta color) top margin correction control for the top margin for cyan, which is the reference station, is performed at the time when registration marks 41.12 are started to be written on the photosensitive drum 1C, that is, by the C registration mark writing signal or VSYNC. 5TA of counter 37C
This C registration mark write signal starts from the time it is sent to the RT terminal, and the S of the VSYNC counter 37C
After being sent to the TART terminal, VSYNC counter 3
Start counting operation by 7C.

Next, when the mark detector 6 detects the first mark of the cyan registration mark image constituting the registration mark 12, the image data C is output from the binarization circuit 32b.
Start signal 5TARTI output according to CDIR
is output, the value of one main scanning period signal CDHSYNC counted by the VSYNC counter 37C, that is, the difference amount C1 is obtained. This difference amount C1 becomes the reference value for top margin correction for the second image forming station.

Therefore, the mark detector 6 detects the registration mark 1 in the same way.
Upon detecting the first mark of the registration mark image for the second image forming station constituting the second image forming station
While the start signal 5TARTI is output in response to the image data CCDIP output from b, VSY
1 main scanning period signal C counted by NC counter 37M
The value of DN5YNC, that is, the difference amount M1 and the above difference amount C
1, etc., and the relative difference is calculated.

Then, each relative difference value is calculated by each VSYNC counter 37.
It is output from M to the third ROM 3B. In response to this, a delay signal DELA which becomes the top margin correction value (a difference value compared with the value output when writing the cyan registration mark) is preliminarily stored in the third ROM 38.
YM is the actuator 26 of the second image forming station
．． The top margin correction is executed by outputting the top margin to 27 or by adjusting the vertical synchronization signal output timing specified for each image forming station. This allows the top margin of the second image forming station to be corrected dependently on the top margin of the cyan image forming station.

Note that each VSYNC counter 37C, 37M receives image data CCD output from the registration mark image of each image forming station sequentially detected by the mark detector 6.
The counting operation ends with the start signal 5TARTI based on IP, but since registration mark images are detected continuously, image data CC at unnecessary positions is
It is necessary to monitor accurately so that the counting operation does not end due to DIP.

Note that the registration mark 11. is detected by the mark detector 5.6.
When the detection of step 12 is completed, the registration mark image transferred to the conveyor belt 4 is cleaned by the cleaner member 8 in preparation for writing the next registration mark.

In addition, in the above embodiment, as shown in FIG.
We have explained the case where the input color information is a two-color copy mode of cyan and magenta, but even if the input color information is three colors, a single color, or a combination with other colors, the colors to be used can be changed in the same way as above. The positional deviation adjustment process is executed as a target, and the reference image forming station can be set arbitrarily.

In addition, especially when the single color mode is specified and input, either the above-mentioned misregistration adjustment is completely prohibited, that is, the misregistration adjustment processing is prohibited at all image forming stations, or the color corresponding to the specified monochrome color is It is sufficient to execute the above-mentioned positional deviation adjustment process only for the image forming station.

Next, an image forming apparatus to which the present invention can be applied will be described with reference to FIGS. 7 to 10.

7(a) and 7(b) are a perspective view and an enlarged perspective view of main parts for explaining an example of an image forming apparatus to which the present invention is applied, and the same parts as in FIGS. 1 and 2 are the same. The symbol is attached.

In these figures, reference numerals 51 and 52 are actuators constituted by, for example, stepping motors, and the actuator 51 moves the optical box 23 with reference to the center °C of a rotating shaft (not shown) inserted into the free through hole of the optical box 23. arrow a
the photosensitive drum 1 from the laser light source 22.
The optical path length of the light beam L emitted to C is adjusted to correct the magnification error.

The actuator 52 rotates the optical box 23 with reference to the center °C of the rotating shaft inserted into the free through hole of the optical box 23, thereby correcting the inclination of the scanning line drawn on the photosensitive drum 1C.

As can be seen from these figures, the reflector 2 shown in FIG.
The present invention can also be applied to an image forming apparatus configured to move the optical box 23 instead of moving the optical box 4, and the scanning line inclination and magnification correction can be performed in the same manner as described above.

8(a) to 8(c) are a perspective view, an enlarged perspective view of a main part, and a cross-sectional view of a main part, illustrating an example of an image forming apparatus to which the present invention is applied, and are the same as FIGS. 1 and 2. Objects are given the same reference numerals.

In these figures, 61C, 61M, 61Y, 61B
K is a flange, photosensitive drum 10.1M, 1Y, I
Fixed to both ends of BK, flanges 61C, 61M, 6
Axis 62C262M, 62Y, 628K to 1Y, 618
However, the bearings are rotatably supported by bearings 64C, 64M, 64Y, and 648K in devices 630°, 63M, 63Y, and 638.

The inner case 6 is attached to the bearings 64C, 64M, 64Y, and 648 so as to be movable in the AA force direction by guide grooves (not shown).
It is supported by 5. Bearing 64C inside each inner case 65
, 64M, 64Y, and 64BK are biased by respective springs 66 and abut on protrusions of an actuator 67 constituted by, for example, a stepping motor.
Move 48K in the AA force direction. A spring 68 biases the inner case 65 housed in the outer case 70.

Reference numeral 69 denotes an actuator constituted by, for example, a stepping motor, which moves the inner case 65 urged by the spring 68 in the BB force direction (which is perpendicular to the AA force direction). Note that the inner case 65 is supported by the outer case 70 by a guide groove (not shown) so as to be movable in the BB force direction, which is perpendicular to the AA force direction.

As shown in FIG. 8(a), the bearings are connected to devices 63C and 63M.
, 63Y, and 638K in the horizontal direction of the AA force direction and the vertical direction of the BB force direction, respectively.
When a pair of actuators provided at both ends of the IBK are simultaneously driven in the same direction, that is, in the BB force direction, the photosensitive drum, for example, the photosensitive drum 1C, is moved approximately parallel to the direction in which the light beam L is emitted from the scanning optical device, and the optical path is The length can be varied to make it possible to correct magnification errors.

Furthermore, when either one of the pair of actuators 67 is moved, each actuator 67 is driven in opposite directions, so that the scanning line inclination can be corrected. Further, by driving the pair of actuators 67 simultaneously, it becomes possible to move the scanning line drawn on the photosensitive drum 1C by the light beam L in parallel, and top margin correction becomes possible.

In this way, the reflector 24 shown in FIG. Figure 7(b)
In addition to individually driving the optical boxes 23 shown in FIG.
Each photosensitive drum IC, IM, IY.

The color misregistration amount correction process according to the present invention can also be applied to an image forming apparatus that serves as a mechanism for individually moving IBKs in a predetermined direction.

Furthermore, as shown in FIG. 9, the present invention can be easily applied to a four-drum color printer having an intermediate transfer material 81, and as shown in FIG. The present invention can be easily applied to a four-drum type color printer that uses one sheet of paper 82, and color misregistration that occurs in each image forming process can be optimally corrected. Note that the above application example was explained for a 4-drum color printer, but for example, a 2-drum color printer is used.
By applying the present invention to color or three-color image forming apparatuses and multiple image forming apparatuses, clear images without image shift can be formed.

In addition, in the above embodiment, a case has been described in which the reflector 24 is integrally formed in a U-shape and a mirror surface is disposed on the opposing surface to scan the light beam L onto the photoreceptor. The angle and the number of mirror surfaces can be freely set without being limited to the above embodiments. For example, the reflector 24 may be formed in an L-shape.

Further, in each of the above embodiments, the actuator mechanism is constructed of, for example, a linear step actuator, but it may also be a normal stepping motor with a screw threaded on the shaft, a cam fixed to the shaft, or a linear motor, etc. It is also possible to provide the same function as the actuator mechanism of the present invention.

Furthermore, in the above embodiment, the case where the registration marks 11 and 12 are transferred using the transport heald 4 as a transport body has been described, or if a known electrophotographic process is used, the transfer material to be transported is The upper position and shape are not limited to the registration marks 11° and 12. For example, marks such as "r" or "-J,!" may be individually transferred to detect image position deviation. You can expect the same effect even if you configure it.

Furthermore, in the above embodiment, the registration marks 11 and 12 transferred to the conveyance heald 4 are cleaned by the cleaner member B such as the cleaning plate 1, for example, or the fur brush method or air suction method is used. By using this, it is possible to collect the toner that has been transferred and landed on the conveyance heald 4, and to prevent errors from forming and reading registration marks 11 and 12 for detecting image position deviation. Alternatively, the image may be reversely transferred to the photosensitive drum using the transfer +I' device and collected by the photosensitive drum cleaner member 8.

In addition, in the above embodiment, the case where the registration mark 11.12 is read by the mark detector 5.6 has been explained, but the number of mark detectors arranged is not limited to two, and more mark detectors can be arranged simultaneously. By arranging multiple registration marks 11, 12 or similar marks on one straight line or on different straight lines and reading them, the image position shift of each photosensitive drum IC, IM, 1Y, 1BK can be detected with high precision. Ru.

[Effects of the Invention] As explained above, the present invention can detect a predetermined one registration mark image among a plurality of resist mark images on each image bearing member transferred to a conveying member sequentially detected by a detection means. The optical beam irradiation start position to each remaining image carrier and the irradiation angle of the optical beam to each remaining image carrier based on the relative difference with the image detection timing of each remaining resist mark.

A correction means for individually correcting the optical beam path length to each of the remaining image carriers, and a correction processing restriction means for limiting execution of correction processing to each image carrier by the correction means based on the input color information to be used. With this arrangement, the image carrier corresponding to the color used can be limited to the object of color shift adjustment, so that the color shift adjustment time can be significantly shortened, and images of the required colors can be overlapped with high precision.

In addition, while the image forming process corresponding to the used color information is being executed, the positional shift adjustment process of each image forming station corresponding to the unused color can be stopped, so the image forming process of each image forming station corresponding to the unused color can be stopped. This has many excellent effects, such as prolonging the life of an engaging member fixed to a driving member used for the purpose, such as a drum motor or a sleeve motor.

[Brief explanation of the drawing]

FIG. 1 is a perspective view illustrating the configuration of a four-drum, full-power, single-type image forming apparatus without showing an embodiment of the present invention, and FIG. 2 shows a structure of the scanning mirror and optical scanning system shown in FIG. 3(a) to 3(C) are schematic diagrams illustrating image shift of the image carrier, and FIG. 4 shows the internal configuration of the controller 1-roller shown in FIG. 1. Control block diagram to explain,
5 is a diagram explaining the registration mark reading operation by the mark detector shown in FIG. 4, FIG. 6 is a timing chart explaining the operation of FIG. 4, and FIG. 7(a),
8(b) is a perspective view and an enlarged perspective view of essential parts illustrating an example of an image forming apparatus to which the present invention is applied, and FIGS. 8(a) to 8(C) are
) are a perspective view, an enlarged perspective view of a main part, a sectional view of a main part, and FIGS. 9 and 10 for explaining an example of an image forming apparatus to which this invention is applied.
Figure 11 is a cross-sectional view illustrating an example of an image forming apparatus to which the present invention is applied, Figure 11 is a schematic diagram illustrating the configuration of a four-tram full-force type image forming apparatus, and Figure 12 illustrates types of image shift. FIG. 13 is a schematic diagram illustrating image deviation caused by positional deviation of the optical scanning system. FIG. 14 is a schematic diagram illustrating image blurring caused by positional deviation of the photosensitive drum axis. FIG. 16 is a schematic diagram illustrating an image shift caused by an error in the optical path length of a light beam. FIG. 16 is a schematic diagram illustrating a magnification error caused by an error in the optical path length of a light beam. In the figure, 1C, 1M, 1Y, iBK are photosensitive trams, 2C,
2M, 2Y, 2BK are scanning mirrors, 3C, 3M, 3Y,
3BK is an optical scanning system, 4 is a conveyance hell 1~. 5.6 is a mark detector, 11.12 is a registration mark, and 13 is a controller. 4-Kikuichi 12 (b) ゛guko

Claims (2)

[Claims] (1) a plurality of image carriers arranged at predetermined intervals;
In an image forming apparatus having a detection means for detecting each registration mark image formed on each image carrier and sequentially transferred to a conveyance body, each image carrier transferred to the conveyance body is sequentially detected by the detection means. A light beam irradiation start position for each remaining image carrier based on a relative difference between a predetermined one registration mark image detection timing and each remaining registration mark image detection timing in a plurality of registration mark images, and a light beam irradiation start position for each remaining image carrier. a correction means for individually correcting the irradiation angle of the light beam and the optical path length of the light beam to each of the remaining image carriers, and execution of correction processing on each image carrier by the correction means based on the input color information to be used. An image forming apparatus comprising: correction processing limiting means for limiting correction processing. (2) An image forming apparatus characterized in that the correction processing limiting means suspends the correction processing of each image carrier by the correction means when the input color information to be used specifies a single color.