JPH08305108A - Image forming device and registration correcting method thereof - Google Patents

Abstract

PURPOSE: To always form a high-quality image not having color smear, without futily interrupting the formation of an image by making the number of the execution times of a registration correcting mode extremely little and executing the registration correcting mode with proper timing. CONSTITUTION: This image forming device is constituted so that a deciding means successively decides whether the execution of the registration correcting mode is required or not from the execution history of the registration correcting mode by a controller 1 for executing the registration correcting mode for mechanically or electrically correcting the registration of each image forming station, based on the results of the detections of sensors 21 and 22 and the execution of the registration correcting mode is suspended with the result of the decision.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus having a plurality of image carriers and capable of multiple-transferring each image formed on each image carrier onto a recording medium, and a registration correction method for the image forming apparatus. It is a thing.

[0002]

2. Description of the Related Art FIG. 5 is a schematic perspective view illustrating the structure of an image forming apparatus of this type.

In the figure, a laser beam emitted from a laser light source (not shown) is bidirectionally scanned by a rotary polygon mirror 103 rotating in the direction of arrow B in the figure, and cyan (C), magenta (M), and yellow (Y). ), Fθ lens (not shown) corresponding to black (BK)
Scanning line 102C passing through the fθ lens,
Photosensitive drums 101C, 101M, 101 that rotate in the direction of arrow A in the figure by 102M, 102Y, 102BK
An image is formed on the Y and 101BK, and a multiple image is formed by performing multiple transfer on the transfer material 105 conveyed in the arrow X direction in the drawing.

Reference numeral 13 is a transfer belt, and 31 is a transfer belt driving roller. 6C-8C, 6M-8M, 6Y-
8Y and 6BK to 8BK are reflection mirrors (mirrors).

As described above, 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 105, so that the transfer image position in each image forming station deviates from the ideal position. For example, in the case of a multicolor image, the image intervals of different colors are shifted or overlapped, and in the case of a color image, the difference in color tint, and when the degree is more severe, the color shift appears and the image quality is improved. It had deteriorated significantly.

FIG. 6 is a diagram for explaining the types of positional deviation of the transferred image of the image forming apparatus shown in FIG.

By the way, as the kind of positional deviation of the transferred image, as shown in FIGS. 6A to 6D, the positional deviation (top margin) in the scanning line writing direction (direction A in the drawing) (FIG. 6 (a)), positional deviation (left margin) in the scanning direction (B direction orthogonal to A direction in the drawing) (see (b) in FIG. 6), tilt deviation in diagonal direction ((c) in FIG. 6) ), A magnification error shift (see FIG. 6D), etc., and in reality, the above four types of shifts are superimposed. The cause of the above-mentioned deviation is shown below.

FIG. 7 is a plan view of the exposure unit of the multiplex image forming apparatus shown in FIG. 5, which shows the photosensitive drums 101M and 101Y.
The upper scanning lines 102M and 102Y are shown developed in the same plane. The scanning lines 102C and 102BK are omitted because they are the same as the scanning lines 102M and 102Y on a plane.

In FIG. 7, reference numeral 401 denotes a lens stand as an optical stand on which one of the bidirectional optical systems is arranged. The cyan and magenta laser light sources 402C, 402M and f.theta.
A lens 403 and the like are attached. Reference numeral 404 denotes a lens base as an optical base on which the other optical system of the two directions is arranged. The yellow and black laser light sources 402Y, 402
02BK, fθ lens 405 and the like are attached.
These lens mounts 401 and 404 are used for the rotary polygon mirror 103.
Is held on a base 406 serving as a support together with the motor housing 415 in which the base is housed. The base 406 is positioned on the apparatus main body 407 and attached with three screws 410.

Then, a bidirectional two-system optical system, that is, an optical central axis 41 of each of the fθ lenses 403 and 405.
1, 412 are arranged so as to coincide with the optical centers 413, 414 of each of the two directions on the reflecting surface of the rotary polygon mirror 103. Further, the lens bases 401 and 404 can rotate in the same plane with the optical centers 413 and 414 in the direction of the center a, and after adjusting one-side magnification of the scanning lines 422M and 422Y, respectively, by three screws 409C and 409Y, respectively. It is fixed to the base 406 at an arbitrary position.

When the apparatus is operated in such a structure, the rotary polygon mirror 103 in the motor housing 415 is rotated at a high speed by a motor (not shown).

Further, laser light sources 402C, 402M,
Laser drivers 408C, 408M, 408Y, 4 which are electric boards for blinking 402Y, 402BK
A current flows through 08BK. These motors and laser drivers are heat sources and serve as lens bases 401, 404 and base 4
06 will be overheated and each will be heated.

However, since there is a temperature gradient near and away from the heat source, the exposed portion does not extend uniformly, so that the lens stands 401, 404 and the base stand 406 are displaced vertically.
That is, warpage occurs. When such warpage occurs, the scanning position of the scanning line on the photosensitive drum changes and the scanning accuracy deteriorates. Hereinafter, the process of the reduction will be described with reference to FIG.

FIG. 8 is a cross-sectional view of essential parts for explaining the structure of the rotary polygon mirror 103 shown in FIG.

Note that the base 406 is provided for simplification of description.
Does not change, and only the lens base 401 changes.

In FIG. 8A, as described above, the lens base 401 does not move at the fixed position of the screw 409, and the central portion is curved in the vertical direction, that is, the Z direction. Lens stand 40
When 1 is curved, the laser mounting portion around it is also deformed to change the irradiation direction of the laser light, and the reflection position of the laser light on the rotary polygon mirror 103 is changed from the position (1) to the position (2). When the reflection position on the rotary polygon mirror 103 is changed to the position (2), the scanning position is changed to the position (3) as shown in FIG. 8B.
It changes from (4) to.

When the scanning position changes in this way, the image writing position also changes, and the scan line curve also increases. In a color printer that obtains a color image by superimposing a plurality of laser beams, these changes appear in the image as color misregistration and tint change, and significantly deteriorate the image quality.

FIG. 9 is a schematic sectional view for explaining the laser scanning system of the image forming apparatus shown in FIG. 5, and FIG.
Photosensitive drums 101C, 101M, 101Y, 1 shown in
FIG. 11 is a cross-sectional view of a main portion showing 01BK and an image transfer position shift.

In the image forming apparatus constructed as shown in FIG. 9, when the temperature of each part inside the apparatus rises as the apparatus is used, the transfer belt drive roller 31 causes the transfer belt drive roller 31 to respond to the linear expansion coefficient of the material, the diameter, and the temperature rise amount. The diameter increases. Since the transfer belt drive roller 31 is rotating at a constant angular velocity, the moving speed v of the transfer belt 13 is increased by Δv. That is, the transfer belt 13 moves by v + Δv. Then, the top margin changes as shown in FIG.

As shown in FIG. 10, the photosensitive drum 101
C, 101M, 101Y and 101BK are arranged at a constant interval. In this case, the transfer belt 1
If the moving speed of 3 is a normal moving speed, the photosensitive drum 1
Position C where the image is transferred to the transfer material 105 at 01C
However, since the speed of the transfer belt 13 is high, the image is transferred to the position M which is delayed from the position C on the photosensitive drum 101M.

Similarly, the photosensitive drums 101Y and 101BK
The images of Y and BK at are also transferred to the delayed positions Y and BK as shown. In other words, a delay level (plus level) top margin shift occurs. Next, when the temperature of each part rises as the apparatus is used, the position of the side plate supporting the photosensitive drum shaft also changes according to the linear expansion coefficient and size of the material and the amount of temperature rise, as shown in FIG.

FIG. 11 shows the photosensitive drum 101 shown in FIG.
FIG. 6 is a cross-sectional view of relevant parts showing C, 101M, 101Y, and 101BK and image transfer position shifts.

As shown in this figure, when the temperature of each part rises as the apparatus is used, the position of the side plate supporting the photosensitive drum shaft also changes according to the linear expansion coefficient of the material and the size and the amount of temperature rise. For example, considering the photosensitive drum 101C as a reference,
Photosensitive drums 101C, 101M, 101Y, 101BK
The position change amount (ΔL, 2ΔL, 3ΔL) increases in the order of. Then, since the transfer material 105 moves at a constant speed v, the transferred image has the transfer positions M, Y, and BK advanced with respect to the position C, and as a result, the top margin shift of the advanced level (minus level) occurs. Occurs.

On the other hand, when the side plate of the housing is thermally expanded in the same manner as above, the position of the reflection mirror supported by the side plate is also as shown in FIG.
It changes as shown in.

FIG. 12 and FIG. 13 are cross-sectional views of the essential parts showing the image transfer position shift with the photosensitive drums 101C, 101M, 101Y and 101BK shown in FIG.

As shown in this figure, when the side plate of the apparatus housing is thermally expanded in the same manner as described above, considering the photosensitive drum 101C as a reference, for example, in the x direction (paper transport direction).
The optical path length changes as the mirror positions of all stations change. Note that the amount of change is the photosensitive drum 10
It depends on the distance from 1C and is not constant.

Further, when the side plate of the apparatus casing is thermally expanded in the same manner as described above, the position of the mirror changes when the position changes in the y direction, for example, so that the optical path length and each photosensitive drum 101.
The laser light irradiation position on C, 101M, 101Y, 101BK changes, resulting in magnification deviation and top margin deviation. Further, in reality, the top margin and front margin of the apparatus are not equal to each other, so that an inclination deviation and a left margin deviation also occur.

There are the following correction means for correcting the four types of deviations described above.

FIG. 14 is a schematic perspective view of a main part for explaining a resist correction mechanism of this type of image forming apparatus, and FIG.
It is a schematic diagram explaining the registration correction state corrected by the registration correction mechanism shown in FIG.

Regarding the top margin left margin, the shift amount is corrected by electrically adjusting the scan timing of the scan lines 102C, 102M, 102Y, 102BK. As for the magnification error deviation and the inclination deviation, a substantially C-shaped mirror pair is formed by forming the mirrors 6 and 7 as a pair at right angles among the folding mirrors in the optical path of each station.
As shown in, the amount of deviation can be corrected by independently adjusting the apparatus main body in the arrow E direction and the arrow F direction.

Actuators 27 to 29 such as linear step actuators having a step motor, which is a drive source for linearly moving in stages, are provided as adjusting means for performing these adjustments. Here, the actuator 27 is moved substantially parallel to the arrow E1 direction of FIG.
Photosensitive drums 101C, 101M, 101Y, 101BK
By shortening the optical path length to the upper side and driving the actuator 27 in the direction of arrow E2 in FIG. 14, the optical path length can be adjusted to be long.

By thus adjusting the optical path length, the scanning lines 102C and 102 having a predetermined spread angle.
M, 102Y, 102BK photosensitive drums 101C, 10
The length on the surface of 1M, 101Y, 101BK can be changed from the scanning line m0 to the scanning line m1 as shown in (a) of FIG. 15, for example.

By driving the actuators 28 and 29 in the same direction at the same time, for example, in the direction of arrow F2 in FIG. 15, the pair of mirrors 6 and 7 are parallel to the F direction which is a direction substantially perpendicular to the E direction. Has been moved, which results in FIG.
The scanning line m0 shown in (b) can be moved to the position of the scanning line m2.

Further, when either one of the actuators 28 and 29 is moved, or when the actuators 28 are driven in the directions of the arrow F1 and the actuator 29 in the directions of the arrow F2, the opposite directions are applied. The inclination angle of the scanning line m0 in FIG. 15C can be changed like the scanning line m3.

As described above, the mirrors 6 and 7 in which a pair of mirrors are assembled at substantially right angles are provided in the optical path of the scanning lines 102C, 102M, 102Y and 102BK from the scanning optical device to the photosensitive drums 101C, 101M, 101Y and 101BK. By adjusting the positions of the pair of mirrors 6 and 7 with the actuator 27 or the actuators 28 and 29.
The scanning positions of M, 102Y, and 102BK can be adjusted independently.

That is, by moving the pair of mirrors 6 and 7 arranged in a V shape in the E direction, the photosensitive drum 1
01C, 101M, 101Y, 101BK without changing the positions of the scanning lines 102C, 102M, 102Y, 102BK imaged on the scanning lines 102C, 102M, 1
Only the optical path length of 02Y, 102BK can be corrected, and the scanning lines 102C, 102M, 102Y, 102 can be moved by moving the pair of mirrors 6, 7 in the F direction.
The photosensitive drum 101C, without changing the optical path length of BK,
It is possible to correct the imaging position (top margin) and the angle on 101M, 101Y, and 101BK.

By using the method as described above, it is possible to match the magnification error deviation, inclination deviation, top margin and left margin of the other three scanning lines with the reference scanning line 102C. Becomes

The following proposals have been made as a method of detecting each deviation amount of the image forming apparatus having the above-mentioned scanning line deviation correction means.

In each image station, registration marks serving as misregistration detection marks are formed at predetermined intervals, the registration marks are transferred onto the transfer belt 13, and the registration marks transferred onto the transfer belt are read. Based on the reading result, the above four types of deviation amounts are calculated.

[0040]

However, in the above method, a correction mode different from the normal image forming mode must be executed. The correction mode is a series of sequence of "formation, reading, calculation of the registration mark, and correction of the above-mentioned four kinds of deviations". That is, during that time, there is a problem that normal image formation is performed.

The present invention has been made in order to solve the above problems, and an object of the first to fourth inventions of the present invention is to determine the next registration from the execution history contents of the registration correction mode. By executing the registration correction mode by controlling whether registration correction mode execution is unnecessary and controlling unnecessary registration correction mode execution, the registration correction mode can be executed at appropriate timing. An object of the present invention is to provide an image forming apparatus and a registration correction method for the image forming apparatus that can always form a high-quality image without color misregistration without interrupting formation unnecessarily.

[0042]

According to a first aspect of the present invention, in an image forming apparatus having a plurality of image forming stations of different colors, a conveying means for conveying a transfer material,
Detecting means for detecting a predetermined image formed at each image forming station and transferred to the conveying means, and mechanically or electrically correcting the registration of each image forming station based on the detection result of the detecting means. Correction means for executing the registration correction mode; determination means for sequentially determining whether or not to execute the registration correction mode based on the execution history of the registration correction mode by the correction means; and the determination means based on the determination result of the determination means. And a control means for suspending execution of the registration correction mode.

According to a second aspect of the present invention, the correction means is
The registration correction mode is executed every predetermined time after the power of the apparatus main body is turned on.

According to a third aspect of the present invention, a temperature sensor for detecting the temperature inside the apparatus main body is provided, and the correction means executes the registration correction mode based on the temperature detected by the temperature sensor.

According to a fourth aspect of the present invention, a plurality of temperature sensors for detecting the temperature inside the apparatus main body are provided, and the correction means is
The registration correction mode is executed based on the temperature difference between the detected temperatures detected by the temperature sensors.

According to a fifth aspect of the present invention, latent image forming means for forming a latent image by scanning an optical scanning system on a photoconductor with modulated laser light, and a latent image formed on the photoconductor. Image forming stations having developing means for making an image visible with a developer are juxtaposed for the number of development colors, and further, conveying means for conveying a transfer material and transfer means formed at each image forming station and transferred to the conveying means. An image forming apparatus having a detection unit that detects a predetermined image and a correction unit that executes a registration correction mode that mechanically or electrically corrects the registration of each image forming station based on the detection result of the detection unit. In the registration correction method, the necessity of executing the registration correction mode is sequentially determined from the execution history of the registration correction mode by the correction unit. A determining step, and has a resting step of resting the execution of the registration correction mode based on the determination result.

[0047]

According to the first aspect of the invention, the registration correction is performed by the correction means for executing the registration correction mode in which the determination means mechanically or electrically corrects the registration of each image forming station based on the detection result of the detection means. Whether or not the registration correction mode should be executed is sequentially determined from the execution history of the modes, and the control means suspends the execution of the registration correction mode based on the result of the determination, and makes any correction by executing the previous registration correction mode. If the above is not performed, it is not necessary to intentionally execute the registration correction mode, and it is possible to avoid the interruption of image formation during that period.

In the second aspect of the invention, the correction means executes the registration correction mode every time a predetermined time elapses after the power of the apparatus main body is turned on, and corrects the registration deviation of each station due to the image forming process every predetermined time. It is possible to do.

In the third invention, a temperature sensor for detecting the temperature inside the apparatus main body is provided, and the correction means executes the registration correction mode based on the temperature detected by the temperature sensor to raise the temperature inside the apparatus main body. It is possible to execute the registration correction mode each time a predetermined temperature is detected based on the temperature characteristic, detect the predetermined temperature, and correct the registration deviation of each station due to the image forming process.

In the fourth aspect of the invention, the registration correction mode is executed based on the temperature difference between the detected temperatures detected by the temperature sensors, and each time the predetermined temperature difference is detected based on the temperature rise characteristic in the apparatus main body. It is possible to execute the registration correction mode to detect the temperature difference and correct the registration deviation of each station due to the warp of each part.

In the fifth aspect, whether or not the registration correction mode should be executed is sequentially determined from the execution history of the registration correction mode by the correction means.
When the execution of the registration correction mode is suspended based on the determination result and no correction is performed by the previous execution of the registration correction mode, it is not necessary to execute the registration correction mode intentionally. It is possible to automate the process for avoiding the interruption of the image formation.

[0052]

1 is a perspective view for explaining the structure of an image forming apparatus showing an embodiment of the present invention, and the same parts as those in FIG. 5 are designated by the same reference numerals. Note that the basic image forming operation in this figure has been described in FIG. 5, and is omitted here.

In the figure, 1 is a CPU, RAM, ROM
Is a controller for registration correction, which executes registration correction processing (correction mode processing) as shown in FIG.

Correspondence between the present embodiment and each means of the first to fourth inventions and their functions will be described below with reference to FIG.

According to a first aspect of the invention, in an image forming apparatus having a plurality of image forming stations of different colors, a conveying means (conveying belt 113) for conveying a transfer material, and the conveying means formed at each image forming station. A detection unit (sensors 21 and 22) for detecting a predetermined image transferred to the image forming apparatus, and a registration correction mode for mechanically or electrically correcting the registration of each image forming station based on the detection result of the detection unit. Correction means to execute (the CPU of the controller 1 controls the drive of the actuators 27 to 29 to perform mechanical correction, and also controls the image writing timing by the light beam of each image forming station to electrically correct). From the registration correction mode execution history by the correction unit, the registration correction mode The sensor is provided with a determination unit (CPU of the controller 1) for sequentially determining the necessity of rows and a control unit (CPU of the controller 1) for suspending execution of the registration correction mode based on the determination result of the determination unit. The registration correction is performed from the execution history of the registration correction mode by the controller 1 that executes the registration correction mode in which the determination unit mechanically or electrically corrects the registration of each image forming station based on the detection results of 21 and 22. Whether or not the mode execution is required is sequentially determined, the execution of the registration correction mode is suspended based on the determination result, and if no correction is performed by the previous execution of the registration correction mode, the registration is dared. You do n’t have to run the correction mode It is possible to avoid that during the image formation is interrupted.

A second aspect of the present invention is a correction means (controller 1
The CPU controls the drive of the actuators 27 to 29 to perform mechanical correction, and also controls the image writing timing by the light beam of each image forming station to electrically correct) for a predetermined time after the power of the apparatus main body is turned on. It is possible to execute the registration correction mode every time the time elapses, and to correct the registration deviation of each station associated with the image forming process every predetermined time.

In a third aspect of the present invention, a temperature sensor (composed of a thermistor or the like (not shown), one of which is provided in the vicinity of the polygon mirror drive motor and the other of which is provided at a predetermined position in the apparatus) for detecting the temperature in the apparatus main body, is provided. The correction means (the CPU of the controller 1 controls the drive of the actuators 27 to 29 to perform mechanical correction and also controls the image writing timing by the light beam of each image forming station to electrically correct). It is possible to execute the registration correction mode based on the temperature detected by the temperature sensor, detect a predetermined temperature, and correct the registration deviation of each station due to the image forming process.

A fourth aspect of the present invention is a correction means (controller 1
CPU controls the drive of the actuators 27 to 29 for mechanical correction, and also controls the image writing timing by the light beam of each image forming station for electrical correction). Run the registration correction mode based on the temperature difference,
It is possible to execute the registration correction mode each time a predetermined temperature difference is detected based on the temperature rise characteristics inside the device body, detect the temperature difference and correct the registration deviation of each station due to the warp of each part. And

FIG. 2 is a flow chart showing an example of the registration correction processing procedure of the image forming apparatus according to the present invention. Note that (1) to (4) indicate each step.

First, the controller 1 forms a registration mark of each color on each photosensitive drum 101 via a laser driver (not shown) (1) and further transfers it onto the transfer belt 13. The registration marks are formed in the back and front of the transfer belt 13 in the conveying direction X, and the registration marks are formed by the registration mark reading means (sensor) 2
1, 2 (2). The registration mark read data is sent to the controller 1, and within the controller 1, magnification error deviation, inclination deviation, top margin deviation, left margin deviation, and four deviation amounts are calculated (3). Then, the correction of these four deviation amounts is executed (4).

Specifically, regarding the top margin deviation and the left margin deviation, the scanning lines 102C and 102
The scanning timings of M, 102Y, and 102BK are electrically corrected.

On the other hand, with respect to the magnification shift and the tilt shift, as described with reference to FIG.
Mirror 6, mirror 7 by driving 8, 29
Is corrected by moving.

As a result, the registration of the image formed at each image station is the same on the transfer material, and an image without color misregistration can be obtained.

In this embodiment, the mode for executing the correction process shown in FIG. 2 is called "registration correction mode". In this registration correction mode, in the present embodiment, a program that is periodically executed after the power of the apparatus main body is turned on is stored in the ROM.

For example, if the registration correction mode is set to be executed every 30 minutes after the power is turned on, the misregistration due to the temperature rise after the power is turned on can be corrected every 30 minutes.
However, executing the registration correction mode every 30 minutes means that there is a time zone in which normal image formation cannot be performed every 30 minutes, and if 8 hours a day,
16 times a day, normal image forming activities will be interrupted.

Therefore, in this embodiment, "history judgment processing"
In order to reduce the number of executions of the registration correction mode, it is determined whether or not it is necessary to execute the registration correction mode based on the history so far.

The "history determination process" is, for example, the registration correction mode executed at the same time last time (time after power-on), and when the registration correction amount is "0" (see the flowchart of FIG. 2). In the calculation of the registration correction amount, when the correction amounts of the magnification, the inclination, the top, and the left are all “0”), it is determined that “registration correction mode is not necessary to be executed at that time on that day”, The registration correction mode is not performed.

FIG. 3 is a flowchart showing an example of a first registration correction processing procedure in the image forming apparatus according to the present invention. Note that (1) to (5) indicate each step.

When the power is turned on (1), the time from the power on is started by the internal timer of the controller 1 (2), and it is judged whether or not the set time tk has been reached (3). In this embodiment, the set time tk is set, for example, every 30 minutes after the power is turned on, but it can be set arbitrarily.

When it is determined in step (3) that the set time tk has been reached, whether or not it is necessary to execute the registration correction mode is determined based on the history so far (4).

In this embodiment, for example, when the registration correction amount is "0" in the registration correction mode executed under the same set time condition of the previous day, "execution of the registration correction mode under the set time condition of the day" is executed. Is unnecessary ", the process returns to step (3) without performing the registration correction mode, and if NO, the registration correction mode process shown in FIG. 2 is executed (5) and the process proceeds to step (1). Return.

In the above embodiment, the necessity of execution of the registration correction mode is determined using time as a parameter, but as shown in FIG. 4, the necessity of execution of the registration correction mode is determined using temperature as a parameter. Good.

FIG. 4 is a flow chart showing an example of the second registration correction processing procedure in the image forming apparatus according to the present invention. Note that (1) to (5) indicate each step.

When the power is turned on (1), the controller 1 starts monitoring the temperature rising state after the power is turned on from the output from a sensor (a temperature sensor composed of a thermistor or the like) not shown (2), and the setting is made. It is judged whether the temperature Tk has been reached (3). The set temperature Tk in this embodiment can be arbitrarily set according to the temperature rising characteristics.

When it is determined in step (3) that the set temperature Tk has been reached, whether or not it is necessary to execute the registration correction mode is determined based on the history so far (4).

In the present embodiment, for example, when the registration correction amount is "0" in the registration correction mode executed under the same temperature condition of the previous day, "the registration correction mode under the temperature condition of the day needs to be executed. If there is none, the registration correction mode is not performed, and the process returns to step (3) and NO.
If so, the registration correction mode process shown in FIG. 2 is executed (5), and the process returns to step (1). In this way, the internal temperature monitor is used, and when the temperature reaches a certain set temperature Tk, the registration correction is performed. As a monitor of the temperature inside the machine, one closely related to the change in the cash register due to temperature rise,
For example, a temperature sensor such as a thermistor may be provided near the scanner motor 103M and the output of the temperature sensor may be used.

In addition to the temperature sensor near the scanner motor 103M, another temperature sensor for monitoring the temperature inside the machine is provided, and the output difference between the two sensors, that is, the temperature difference is used as a parameter to determine the temperature difference. The registration correction mode may be executed when a certain value is reached.

The “history judgment” shown in step (4) in FIGS. 3 and 4 is for judging whether or not there is a necessity of executing the registration correction mode from the past execution history of the registration correction mode. However, the purpose is to reduce the number of executions of the registration correction mode and reduce the downtime of the apparatus, and therefore the criterion for determination is not limited to the above example.

In the above-described embodiment, whether or not the registration correction mode is necessary is determined based on the data of the previous day, but other than that example, it may be based on data of several days.
Further, the registration correction amount is not limited to “0”, but may be determined based on a certain threshold value.

Correspondence between the present embodiment and each step of the fifth invention and its action will be described below with reference to FIGS.

A fifth aspect of the invention is a latent image forming means (reflection mirrors 106C, 107C, 108) for forming a latent image by scanning the photosensitive member with an optical scanning system by means of modulated laser light.
C, 106M, 107M, 108M, 106Y, 107
Y, 108Y, 106BK, 107BK, 108BK)
And a developing unit that visualizes the latent image formed on the photoconductor with a developer, the image forming stations are arranged side by side for the number of development colors, and further, a conveying unit (conveying belt 113) that conveys the transfer material. And detection means (sensors 21 and 22) for detecting a predetermined image formed at each image forming station and transferred to the conveying means, and registration of each image forming station based on the detection result of the detecting means. A registration correction method for an image forming apparatus having a correction unit (by the CPU of the controller unit 1) for executing a registration correction mode for mechanically or electrically correcting a registration correction mode executed by the correction unit. Judgment step (step (4) in FIG. 3 and FIG. 4) for sequentially judging whether or not to execute the registration correction mode. And a step of stopping the execution of the registration correction mode based on the determination result (step of returning from step (4) to step (3) in FIGS. 3 and 4) to execute the previous registration. When no correction is performed by executing the registration correction mode, it is not necessary to intentionally execute the registration correction mode, and it is possible to automate the process of avoiding the interruption of image formation during that period.

[0082]

As described above, the first aspect of the present invention
According to the invention, the determining means drives the adjusting means on the basis of the detection result of the detecting means to execute the registration correcting mode for mechanically or electrically correcting the registration of each image forming station. Whether or not to execute the registration correction mode is sequentially determined from the execution history of the registration correction mode, and the control means suspends the execution of the registration correction mode based on the determination result. Thus, if no correction is performed, it is not necessary to intentionally execute the registration correction mode, and it is possible to avoid interruption of image formation during that time.

According to the second aspect of the present invention, the correction means executes the registration correction mode every time a predetermined time elapses after the power of the apparatus main body is turned on. It is possible to correct.

According to the third invention, a temperature sensor for detecting the temperature in the main body of the apparatus is provided, and the correction means executes the registration correction mode based on the temperature detected by the temperature sensor, and Since the registration correction mode is executed every time when the predetermined temperature is detected based on the temperature rise characteristic, it is possible to detect the predetermined temperature and correct the registration deviation of each station due to the image forming process.

According to the fourth aspect of the invention, the registration correction mode is executed based on the temperature difference between the detected temperatures detected by the temperature sensors, so that the predetermined temperature difference is detected based on the temperature rise characteristic in the apparatus main body. It is possible to execute the registration correction mode for each time and detect the temperature difference to correct the registration deviation of each station due to the warp of each portion.

According to the fifth aspect, whether or not the registration correction mode should be executed is sequentially judged from the execution history of the registration correction mode by the correction means, and the registration correction mode is executed based on the judgment result. Since there is no correction by the previous execution of registration correction mode,
It is not necessary to dare to execute the registration correction mode, and it is possible to automate the process of avoiding the interruption of image formation during that period.

Therefore, by simply reducing the number of executions of the registration correction mode and executing the registration correction mode at an appropriate timing, a high-quality image with no color misregistration is always provided without meaningless interruption of image formation. And the like.

[Brief description of drawings]

FIG. 1 is a perspective view illustrating a configuration of an image forming apparatus according to an exemplary embodiment of the present invention.

FIG. 2 is a flowchart showing an example of a registration correction processing procedure of the image forming apparatus according to the present invention.

FIG. 3 is a flowchart showing an example of a first registration correction processing procedure in the image forming apparatus according to the present invention.

FIG. 4 is a flowchart showing an example of a second registration correction processing procedure in the image forming apparatus according to the present invention.

FIG. 5 is a schematic perspective view illustrating the configuration of this type of image forming apparatus.

6A and 6B are diagrams illustrating types of positional deviation of a transfer image of the image forming apparatus illustrated in FIG.

7 is a plan view of an exposure unit of the multiplex image forming apparatus shown in FIG.

8 is a cross-sectional view of a main part for explaining a configuration around a rotary polygon mirror shown in FIG.

9 is a schematic cross-sectional view illustrating a laser scanning meter of the image forming apparatus illustrated in FIG.

FIG. 10 is a cross-sectional view of a relevant part showing the displacement of an image transfer position between each photosensitive drum shown in FIG.

FIG. 11 is a cross-sectional view of relevant parts showing the displacement of image transfer positions between the photosensitive drums shown in FIG. 9;

FIG. 12 is a cross-sectional view of a relevant part showing the displacement of an image transfer position between each photosensitive drum shown in FIG. 9;

FIG. 13 is a cross-sectional view of relevant parts showing the displacement of image transfer positions between the photosensitive drums shown in FIG. 9;

FIG. 14 is a schematic perspective view of a main part for explaining a resist correction mechanism of this type of image forming apparatus.

15 is a schematic diagram illustrating a registration correction state corrected by the registration correction mechanism illustrated in FIG.

[Explanation of symbols]

 1 Controller 27 Actuator 28 Actuator 29 Actuator

Claims (5)

[Claims] 1. In an image forming apparatus having a plurality of image forming stations of different colors, a conveying means for conveying a transfer material and a predetermined image formed at each image forming station and transferred to the conveying means are detected. Detecting means for performing the registration correction mode for mechanically or electrically correcting the registration of each image forming station based on the detection result of the detecting means, and the registration correction mode by the correcting means. It is characterized by further comprising: determination means for sequentially determining whether or not to execute the registration correction mode from an execution history, and control means for suspending execution of the registration correction mode based on a determination result of the determination means. Image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the correction unit executes the registration correction mode every time a predetermined time elapses after the power of the apparatus main body is turned on. 3. An image forming apparatus according to claim 1, further comprising a temperature sensor for detecting a temperature inside the apparatus main body, wherein the correction unit executes a registration correction mode based on a temperature detected by the temperature sensor. apparatus. 4. A plurality of temperature sensors for detecting the temperature inside the apparatus main body are provided, and the correction means executes the registration correction mode based on the temperature difference between the detected temperatures detected by the temperature sensors. The image forming apparatus according to claim 1. 5. A latent image forming means for forming a latent image by scanning the photoconductor with a modulated laser beam by an optical scanning system and a latent image formed on the photoconductor with a developer. Image forming stations provided with developing means for arranging them in parallel for the number of developing colors, and further, conveying means for conveying the transfer material and detection for detecting a predetermined image formed at each image forming station and transferred to the conveying means. A registration correction method for an image forming apparatus, the correction correction method executing a registration correction mode for mechanically or electrically correcting the registration of each image forming station based on the detection result of the detection means, A determination step of sequentially determining whether or not to execute the registration correction mode from the execution history of the registration correction mode by the correction means; A registration correction method for an image forming apparatus, comprising: a suspension step of suspending execution of the registration correction mode based on a determined result.