JP4439663B2 - Image forming apparatus - Google Patents

Description

[0001]
The present invention relates to a recording material for forming images on a plurality of image carriers using toners of respective colors included in each of a plurality of image forming units and transporting the images of the respective colors formed on the plurality of image carriers. BACKGROUND OF THE INVENTION 1. Field of the Invention
[0002]
[Prior art]
In conventional color image forming apparatuses such as copiers and printers, there is an intermediate transfer method in which toner images formed by a plurality of image forming units are sequentially superimposed on an intermediate transfer member and then transferred to a recording material in a batch. Are known.
[0003]
[Problems to be solved by the invention]
However, in order to obtain a full-color image, the images formed by the plurality of image forming units must be superimposed.
[0004]
Therefore, adjustment for overlapping images is performed in advance before image formation.
[0005]
At this time, a registration pattern is formed on the intermediate transfer member by each image forming unit, and a registration pattern on the intermediate transfer member formed by each image forming unit is detected by a registration sensor which is a detection unit such as a CCD. It was necessary to perform image matching.
[0006]
Image correction (hereinafter referred to as auto-registration) is performed by adjusting image shifts in the main scanning and sub-scanning image writing positions due to temperature changes in the image forming section, changes in magnification, image inclinations due to unit assembly accuracy, and the like.
[0007]
This image alignment (hereinafter referred to as auto-registration mode) is performed when the image forming apparatus is powered on, restarted after jam processing, or after a predetermined time has elapsed since the power was turned on. It takes a long time to detect and provide feedback, which causes a long wait time after the power supply of the image forming apparatus is turned on and a restart time.
[0008]
In particular, when a predetermined number of continuous images have elapsed to correct image displacement due to image writing sections such as laser scanners and distortion to optical components due to temperature rise during continuous image formation, the image correction mode is entered and image correction is performed. It was over.
[0009]
As a result, there is a problem in that the image forming operation is frequently interrupted and the productivity is significantly reduced.
[0010]
The present invention has been made to solve the above-described problems, and an object of the present invention is to reduce the processing time required for image correction during continuous image formation and to achieve a good color image without reducing productivity. It is to provide a mechanism that can be obtained.
[0011]
[Means for Solving the Problems]
The present invention A toner image is formed on each of a plurality of image carriers using toner of each color included in each of a plurality of image forming units, and the toner images formed on each of the plurality of image carriers are transferred onto a recording medium via an intermediate transfer member. In the image forming apparatus that forms a color image by transferring the toner image to the image forming unit, the predetermined toner pattern is formed on the intermediate transfer body in order to form a predetermined toner pattern corresponding to each of a plurality of color toners. Based on pattern detection means formed on each of the plurality of image carriers, detection means for detecting the formation position of the predetermined toner pattern transferred on the intermediate transfer body, and detection results of the detection means, The formation positions of the toner images of the plurality of colors in the conveyance direction of the recording medium and the direction orthogonal to the conveyance direction, the conveyance direction Inclination of the toner image with respect to a direction perpendicular to, and a first correction for correcting the magnification of the toner image, In the transport direction of the recording medium and in the direction perpendicular to the transport direction And a correction unit that executes a second correction for correcting the formation positions of the toner images of the plurality of colors, and the correction unit is configured when the power of the image forming apparatus is turned on or when the power is When a predetermined time has elapsed without image formation after being turned on In Executing the first correction, the image forming unit; By Continuous image formation Has started When an image is formed on a specified number of recording media In When performing the first correction, the correction unit performs the first correction until the formation position of the predetermined toner pattern detected by the detection unit falls within a predetermined range. When the correction is repeated and the second correction is executed, the second correction is not repeated.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
FIG. 1 is a cross-sectional view illustrating the configuration of an intermediate transfer type image forming apparatus to which the image forming apparatus according to the first embodiment of the present invention can be applied.
[0021]
The configuration and operation will be described below.
[0022]
In the figure, reference numeral 1R denotes an image reading unit which reads image data from a document placed on a document reading table. An image output unit 1P forms an image on a recording medium (transfer material P) based on image data input from an external device or a network via an image reading unit 1R or an external interface (not shown).
[0023]
The image output unit 1P is roughly divided into an image forming unit 10 (four stations a, b, c, and d are arranged in parallel, and the configuration is the same), a paper feeding unit 20, an intermediate transfer unit 30, and a fixing unit. 40 and a control unit (not shown) (consisting of a control board 170, a motor drive board (not shown), an external interface (not shown), etc.).
[0024]
Further, each unit will be described in detail.
[0025]
The image forming unit 10 is configured as described below.
[0026]
Reference numerals 11a, 11b, 11c, and 11d denote photosensitive drums as image carriers, which are pivotally supported at the centers and are driven to rotate in the direction of the arrows. The primary chargers 12a, 12b, 12c, 12d, the optical systems 13a, 13b, 13c, 13d, the developing devices 14a, 14b, 14c, in the rotational direction facing the outer peripheral surface of the photosensitive drums 11a, 11b, 11c, 11d, 14d is arranged. In the primary chargers 12a to 12d, charges of a uniform charge amount are given to the surfaces of the photosensitive drums 11a to 11d.
[0027]
Next, the optical systems 13a to 13d expose the photosensitive drums 11a to 11d with light beams such as laser beams modulated according to the recording image signal, thereby forming electrostatic latent images thereon. Further, the electrostatic latent images are visualized by developing devices 14a to 14d that respectively store four color developers (toners) such as yellow (Y), magenta (M), cyan (C), and black (BK). .
[0028]
The visualized visible image is transferred to an intermediate transfer member (intermediate transfer belt 31). On the downstream side of the image transfer areas Ta, Tb, Tc, and Td, the toner remaining on the photosensitive drums 11a to 11d without being transferred to the transfer material by the cleaning devices 15a, 15b, 15c, and 15d is scraped off to form the surface of the drum. Clean.
[0029]
Through the process described above, image formation is sequentially performed using yellow (Y), magenta (M), cyan (C), and black (BK) toners.
[0030]
The paper feeding unit 20 includes cassettes 21a and 21b and a manual feed tray 27 for storing the recording material P, pickup rollers 22a, 22b and 26 for feeding the recording material P one by one from the cassette or the manual feed tray, and each pickup roller. A pair of paper feed rollers 23 and a paper feed guide 24 for conveying the recording material P sent out from the recording roller to the registration rollers, and for feeding the recording material P to the secondary transfer region Te in accordance with the image forming timing of the image forming unit. It consists of registration rollers 25a and 25b.
[0031]
Hereinafter, the intermediate transfer unit 30 will be described.
[0032]
The intermediate transfer belt 31 includes a driving roller 32 that transmits driving to the intermediate transfer belt 31, a tension roller 33 that applies appropriate tension to the intermediate transfer belt 31 by urging of a spring (not shown), and a secondary transfer region across the belt. It is wound around a driven roller 34 facing Te. Among these, a primary transfer plane A is formed between the driving roller 32 and the tension roller 33. The drive roller 32 is coated with rubber (urethane or chloroprene) having a thickness of several millimeters on the surface of the metal roller to prevent slippage with the belt. The drive roller 32 is rotationally driven by a pulse motor (not shown). Primary transfer blades 35 a to 35 d are arranged behind the intermediate transfer belt 31 in primary transfer regions Ta to Td where the photosensitive drums 11 a to 11 d and the intermediate transfer belt 31 face each other.
[0033]
A secondary transfer roller 36 is disposed so as to face the driven roller 34, and a secondary transfer region Te is formed by a nip with the intermediate transfer belt 31. The secondary transfer roller 36 is pressed with an appropriate pressure against the intermediate transfer member. A cleaning device 50 for cleaning the image forming surface of the intermediate transfer belt 31 is disposed on the intermediate transfer belt 31 and downstream of the secondary transfer region Te. The cleaning device 50 includes a cleaner blade 51 (as a material). And a waste toner box 52 for storing waste toner.
[0034]
The fixing unit 40 includes a fixing roller 41a having a heat source such as a halogen heater therein, a fixing roller 41b to which the roller is pressed (the fixing roller 41b may also have a heat source), and a nip of the roller pair. It comprises a guide 43 for guiding the transfer material P to the part, and an inner discharge roller 44 and an outer discharge roller 45 for further guiding the transfer material P discharged from the roller pair to the outside of the apparatus.
[0035]
The control unit includes a control board 170 for controlling the operation of the mechanism in each unit, a motor drive board (not shown), and the like.
[0036]
Next, a description will be added in accordance with the operation of the apparatus.
[0037]
When an image forming operation start signal is issued, first, the transfer material P is sent out one by one from the cassette 21a by the pickup roller 22a. The transfer material P is guided between the paper feed guides 24 by the paper feed roller pair 23 and is conveyed to the registration rollers 25a and 25b. At that time, the registration rollers 25a and 25b are stopped, and the leading edge of the paper hits the nip portion. Thereafter, the registration rollers 25a and 25b start rotating in accordance with the timing at which the image forming unit starts to form an image. The rotation timing is set so that the transfer material P and the toner image primary-transferred onto the intermediate transfer belt 31 from the image forming unit exactly coincide with each other in the secondary transfer region Te.
[0038]
On the other hand, in the image forming unit, when an image forming operation start signal is issued, a high voltage is applied to the toner image formed on the photosensitive drum 11d that is the most upstream in the rotation direction of the intermediate transfer belt 31 by the process described above. Further, primary transfer is performed on the intermediate transfer belt 31 in the primary transfer region Td by the primary transfer charger 35d. The primarily transferred toner image is conveyed to the next primary transfer region Tc. In this case, image formation is delayed by a time during which the toner image is conveyed between the image forming portions, and the next toner image is transferred with the resist aligned on the previous image. Thereafter, the same process is repeated, and eventually, four color toner images are primarily transferred onto the intermediate transfer belt 31.
[0039]
Thereafter, when the recording material P enters the secondary transfer region Te and contacts the intermediate transfer belt 31, a high voltage is applied to the secondary transfer roller 36 in accordance with the passing timing of the recording material P. Then, the four color toner images formed on the intermediate transfer belt 31 by the process described above are transferred onto the surface of the recording material P. Thereafter, the recording material P is accurately guided to the fixing roller nip portion by the conveyance guide 43. The toner image is fixed on the surface of the recording material by the heat of the pair of fixing rollers 41a and 41b and the pressure of the nip. Thereafter, the recording material P is conveyed by the inner and outer discharge rollers 44 and 45, and the recording material P is discharged outside the apparatus.
[0040]
When obtaining a monochromatic image, a monochromatic visible image is primarily transferred onto the intermediate transfer member from a specific image forming unit (for example, the image forming unit d located at the most downstream in the traveling direction of the intermediate transfer member). A monochromatic image is obtained through the same process as that for forming the image.
[0041]
Reference numeral 60 denotes a pair of registration sensors (CCD or an optical sensor composed of an LED light-emitting unit and a photosensor light-receiving unit, etc.). The formed registration pattern (color shift detection pattern shown in FIG. 3 described later) is detected.
[0042]
In the image forming apparatus of the present invention, when entering the auto registration mode, a controller 1000 (described later) controls the registration of each image forming unit by feeding back the read image to the read image by the registration sensor 60 as a detection unit. (Shown in FIG. 2) in the control board 170.
[0043]
FIG. 2 is a block diagram for explaining the configuration of the controller 1000 provided in the control board 170 shown in FIG. 1, and the same components as those in FIG. 1 are denoted by the same reference numerals.
[0044]
In the figure, reference numeral 1021 denotes an A / D unit (analog / digital conversion unit) which digitizes an analog signal (registration pattern detection signal) output from the registration sensor 60.
[0045]
An arithmetic unit 1022 performs arithmetic processing on the data from the registration sensor 60 digitized by the A / D unit 1021, and calculates a displacement amount (main scanning width) and a correction value in the main scanning direction. The image forming unit 10 forms an image according to the calculation result of the calculation unit 1022. A CPU 1018 performs overall control of the entire image forming apparatus based on a program stored in the ROM 1024 or other storage medium (not shown), and performs timing adjustment and various settings of each unit.
[0046]
Reference numeral 1025 denotes a RAM which is used as a work area for the CPU 1018 and includes a non-volatile memory therein to store various settings of the image forming apparatus. A timer 1019 counts the timing at which the registration sensor 60 detects a registration pattern under the control of the CPU 1018.
[0047]
Further, the CPU 1018 controls the image forming unit 10 based on registration pattern data stored in the ROM 1024 or other storage medium (not shown) to form a registration pattern shown in FIG. 3 to be described later on the intermediate transfer belt 31. Further, the CPU 1018 performs image correction (auto registration) by controlling adjustment of the writing timing, magnification, and image inclination of the image forming unit 10 based on the calculation result of the calculation unit 1022.
[0048]
FIG. 3 is a schematic diagram for explaining an auto registration pattern of the image forming apparatus according to the present invention. The same components as those in FIG. 1 are denoted by the same reference numerals.
[0049]
In the figure, 90Y, 90M, 90C, and 90BK are registration patterns of yellow (Y), magenta (M), cyan (C), and black (BK), and are formed on the left and right sides of the intermediate transfer belt 31 in the moving direction. It is comprised by a pair of pattern.
[0050]
The registration patterns 90Y, 90M, 90C, and 90BK are formed on the intermediate transfer belt 31 by the CPU 1018 shown in FIG. 2 controlling the image forming unit 10 (configured by each color image forming unit).
[0051]
The registration patterns 90Y, 90M, 90C, and 90BK are written on the intermediate transfer belt 31 by each color image forming unit, and the position of the registration pattern is detected by the registration sensor 60. Thus, auto registration (automatic registration correction processing) is performed by adjusting the timing of image writing, the magnification, and the inclination of the image.
[0052]
FIG. 4 is a schematic diagram of a registration pattern for explaining the auto registration processing of the image forming apparatus of the present invention. The same reference numerals are given to the same components as those in FIG.
[0053]
In the drawing, L1 is a distance between a pair of patterns constituting a registration pattern 90BK of a reference image forming unit, for example, a black (BK) image forming unit, and L2 is a color other than the black (BK) image forming unit (yellow). (Y), magenta (M), and cyan (C)) are distances between a pair of patterns constituting the registration pattern of the image forming unit.
ΔH is a distance between patterns in the main scanning direction of colors other than black (BK) and black (BK) (yellow (Y), magenta (M), cyan (C)), and corresponds to a deviation amount of the image writing position. To do.
[0054]
ΔV1 and ΔV2 are distances between patterns in the sub-scanning direction of colors other than black (BK) and black (BK) (yellow (Y), magenta (M), cyan (C)).
[0055]
The auto registration routine (normal registration correction processing) of the image forming apparatus of the present invention will be described below. Note that this normal registration correction processing is performed when the image forming apparatus is powered on and then left for a predetermined time.
[0056]
First, the registration patterns 90Y, 90M, 90C, and 90BK are written on the intermediate transfer belt 31 by each color image forming unit, the registration pattern position is detected by the registration sensor 60, and the distance L1 of the reference black (BK) registration pattern 90BK is set. The distance L2 of the registration pattern (90Y, 90M, 90C) of the next image forming unit (yellow (Y), magenta (M), cyan (C)) is calculated, L1 and L2 are compared, and L1 = L2. In this way, the L2 image data (yellow (Y) image data, magenta (M) image data, cyan (C) image data) is controlled to adjust the magnification of the image.
[0057]
Next, in order to perform the image writing position (main scanning writing, left correction), the writing position in the main scanning direction is moved so that ΔH becomes “0”.
[0058]
Thereafter, an image of the registration pattern corrected for magnification and image writing is written on the intermediate transfer belt 31 by each image forming unit.
[0059]
Next, the inclination of the image is corrected.
[0060]
This is achieved by matching the distance ΔV1 with the distance ΔV1 and the registration pattern (black registration pattern 90BK) of the image forming unit serving as a reference.
[0061]
Finally, in order to align the leading edge position of the image, ΔV1 is adjusted to be a predetermined distance X, for example, the interval between the image forming portions.
[0062]
Further, registration patterns 90Y, 90M, 90C, and 90BK are written on the intermediate transfer belt 31 and checked by the registration sensor 60.
[0063]
If the registration (registration) is not correct, this routine is repeated several times to perform image alignment and increase the accuracy.
[0064]
Next, registration correction processing when a predetermined number of images have elapsed in continuous image formation will be described.
[0065]
Due to the temperature rise in the apparatus due to the continuous image formation, the image shift occurs due to the influence of the distortion on the optical components of the image writing unit such as a laser scanner. In order to prevent this, image correction is performed when a predetermined number of images are continuously formed. The image correction performed at this time is dominated by a temperature rise and has a large amount of deviation, leading edge deviation (image writing position deviation in the sub-scanning direction) and image writing position deviation (image writing position deviation in the main scanning direction). Only the correction is performed.
[0066]
The interval between the registration patterns in this mode is set to “1 / n” (n: integer) of the predetermined distance X adjusted when aligning the image leading end position in the normal registration correction process.
[0067]
The registration pattern in this mode is performed in one image frame during the above-described continuous image formation, and the writing position is set so that ΔH becomes “0” in order to perform the image writing position (main scanning writing, left correction). To move.
[0068]
Next, ΔV1 is adjusted to be “1 / n” of the predetermined distance X in order to align the front end position of the image, and the correction process is terminated.
[0069]
Thus, registration can be performed simply, images can be aligned, and the auto registration mode can be set in a short time (automatic registration correction is performed).
[0070]
It should be noted that the registration correction process when a predetermined number of sheets have elapsed in this continuous image formation is also performed at the restart after the jam process.
[0071]
Hereinafter, the registration correction processing of the image forming apparatus of the present invention will be described with reference to the flowchart of FIG.
[0072]
FIG. 5 is a flowchart showing an example of registration correction processing of the image forming apparatus of the present invention, which is executed by the CPU 1018 shown in FIG. 2 based on a program stored in the ROM 1024 or other storage medium (not shown). S101 to S104 indicate each step.
[0073]
First, in step S101, it is determined whether or not a predetermined time has elapsed after the power is turned on or for a predetermined time, and a predetermined time has elapsed after the power is turned on or for a predetermined time. If it is determined that the image is in the state, in step S103, registration correction (shown in FIG. 6 described later) is executed in the first image alignment mode (image alignment mode in which correction items are fully executed), and step S101 is performed. Return to the process.
[0074]
On the other hand, if it is determined in step S101 that the power has been turned on or that the predetermined time has not elapsed after the power is turned on for a predetermined time, in step S102, a state in which a predetermined number of sheets have elapsed during continuous image formation or after jam processing. It is determined whether the image is in the restarted state. If it is determined that the predetermined number of images have elapsed during continuous image formation or the restarted state after the jam processing, the second image alignment mode (execution) is executed in step S104. Registration correction (shown in FIG. 7 to be described later) is executed in the image alignment mode in which correction items to be limited are limited), and the process returns to step S101.
[0075]
On the other hand, if it is determined in step S102 that the predetermined number of sheets have not elapsed during the continuous image formation or the restart state after the jam processing is not completed, the process directly returns to step S101.
[0076]
The registration correction processing operation of the image forming apparatus of the present invention will be described below with reference to the flowcharts of FIGS.
[0077]
FIG. 6 is a flowchart for explaining a registration correction processing procedure in the first image alignment mode (image alignment mode in which correction items are fully executed) of the image forming apparatus according to the present invention. Executed when a predetermined time has elapsed after the power is turned on.
[0078]
This process is executed by the CPU 1018 shown in FIG. 2 based on a program stored in the ROM 1024 or other storage medium (not shown). S201 to S207 indicate each step.
[0079]
First, in step S201, when the registration correction process in the first image alignment mode is started, the registration patterns 90Y, 90M, 90C, and 90BK shown in FIG. 3 are formed and transferred onto the intermediate transfer belt 31, The registration sensor 60 reads and detects the registration displacement amount (detects the position of each registration pattern and calculates L1, L2, ΔH, ΔV1, and ΔV2).
[0080]
Next, in step S202, it is necessary to correct from each registration pattern position detected in step S201 (difference between L1 and L2, ΔH, ΔV1, and difference between ΔV1 and ΔV2 are within a predetermined range). If there is no need, the registration correction processing is returned without performing correction.
[0081]
On the other hand, if it is determined in step S202 that correction is necessary, magnification correction is performed in step S203 (L2 is set to L1), and in step S204, ΔH is set to “0” in the main scanning direction. In step S205, the registration patterns 90Y, 90M, 90C, and 90BK are formed again, transferred onto the intermediate transfer belt 31, and read by the registration sensor 60 to detect the amount of registration deviation (each registration pattern). Is detected, and ΔV1 and ΔV2 are calculated).
[0082]
Next, in step S206, image inclination correction is performed (ΔV2 is adjusted to ΔV1), and in step S207, image leading edge position correction, that is, image writing position correction in the sub-scanning direction is performed (ΔV1 is the interval between photosensitive drums or And the process returns to step S201.
[0083]
FIG. 7 is a flowchart for explaining the registration correction processing procedure in the second image alignment mode (image alignment mode in which the correction items to be executed are limited) of the image forming apparatus of the present invention. It is executed in the restarted state after jamming or jam processing.
[0084]
This process is executed by the CPU 1018 shown in FIG. 2 based on a program stored in the ROM 1024 or other storage medium (not shown). S301 to S304 indicate each step.
[0085]
First, when registration correction processing in the second image alignment mode is started in step S301, the registration patterns 90Y, 90M, 90C, and 90BK shown in FIG. 3 are formed and transferred onto the intermediate transfer belt 31, The registration sensor 60 reads and detects the registration displacement amount (detects the position of each registration pattern and calculates ΔH and ΔV1).
[0086]
Next, in step S302, it is determined whether or not correction is necessary from each registration pattern position detected in step S301 (ΔH and ΔV1 are within a predetermined range). If not, correction is not performed. Return to the registration correction process.
[0087]
On the other hand, if it is determined in step S302 that correction is necessary, image writing position correction in the main scanning direction is performed so that ΔH is “0” in step S303, and image leading edge position correction is performed in step S304. That is, the image writing position correction in the sub-scanning direction is performed (matching so that ΔV1 becomes “1 / n” (n is an integer) of the predetermined distance X (for example, the interval between the photosensitive drums) described above, and the process returns. To do.
[0088]
With the above processing, during continuous image formation, only the registration correction for the main scanning and sub-scanning writing is simply executed, thereby shortening the time required for image correction during continuous image formation and shortening the down mode. , Productivity can be improved and good image quality can be provided.
[0089]
[Second Embodiment]
In the first embodiment, a registration pattern is formed on the intermediate transfer belt 31 that re-transfers each image formed and temporarily transferred by a plurality of image stations a to d to a recording medium, and a registration amount is detected. As described above, the registration pattern is transferred onto the transfer belt for directly transferring the images formed by the plurality of image stations a to d to the recording medium while conveying the recording medium such as paper. May be configured to detect a registration amount. The embodiment will be described below.
[0090]
FIG. 8 is a cross-sectional view for explaining the configuration of the image forming apparatus showing the second embodiment of the present invention, and the same components as those in FIG.
[0091]
The image output unit 1P is roughly divided into an image forming unit 10, a paper feeding unit 20, a transfer unit 70, a fixing unit 40, and a control unit (not shown).
[0092]
Further, each unit will be described in detail. The image forming unit 10 is configured as described below.
[0093]
Hereinafter, the transfer unit 70 will be described.
[0094]
A transfer belt 71 is visible on the photosensitive drums 11a to 11d visualized by the developing devices 14a to 14d in the image transfer regions Ta, Tb, Tc, and Td with respect to the transfer material P while the transfer material P is conveyed. Transfer the image.
[0095]
Reference numeral 72 denotes a driving roller that transmits driving force to the transfer belt 71. The driving roller 72 is coated with rubber (urethane or chloroprene) having a thickness of several millimeters on the surface of the metal roller to prevent slippage with the transfer belt 71. The drive roller 72 is rotationally driven by a pulse motor (not shown).
[0096]
Reference numeral 74 denotes a tensicon roller which applies an appropriate tension to the transfer belt 71 by urging a spring (not shown).
[0097]
75a to 75d are transfer blades, which are arranged behind the transfer areas Ta to Td on the transfer belt 71 where the photosensitive drums 11a to 11d and the transfer belt 71 face each other.
[0098]
A cleaning device 50 is disposed downstream of the transfer area Ta on the transfer belt 71 and cleans the image forming surface of the transfer belt 71. The cleaning device 50 includes a cleaner blade 51 and a waste toner box 52 that stores waste toner.
[0099]
Hereinafter, a description will be added according to the operation.
[0100]
When an image forming operation start signal is issued, first, the transfer material P is sent out one by one from the cassette 21a by the pickup roller 22a. The transfer material P is guided between the paper feed guides 24 by the paper feed roller pair 23 and conveyed to the registration rollers 25a and 25b.
[0101]
At that time, the registration rollers 25a and 25b are stopped, and the leading edge of the paper hits the nip portion. Thereafter, the registration rollers 25a and 25b start rotating in accordance with the timing at which the image forming unit starts to form an image. The rotation timing is set so that the transfer material P and the toner image of the image forming portion exactly coincide with each other at the transfer portion.
[0102]
On the other hand, when the image forming operation start signal is issued, the image forming unit 10 applies a high voltage to the toner image formed on the photosensitive drum 11d that is the most upstream in the rotation direction of the transfer belt 71 by the process described above. The transfer blade 75d is transferred onto the transfer material P in the transfer region Td.
[0103]
The transferred transfer material P is conveyed to the next transfer area Tc. In this case, image formation is performed with a delay by the time during which the toner image is conveyed between the image forming units, and the next toner image is transferred with the resist aligned on the previous image.
[0104]
The same process is repeated thereafter, and eventually, four color toner images are transferred onto the transfer material P.
[0105]
Thereafter, the recording material P is accurately guided to the fixing roller nip portion by the conveyance guide 43. The toner image is fixed on the surface of the recording material by the heat of the roller pair 41a and 41b and the pressure of the nip. Thereafter, the recording material P is conveyed by the inner and outer discharge rollers 44 and 45, and the recording material P is discharged outside the apparatus.
[0106]
When obtaining a monochromatic image, a monochromatic visible image is transferred onto a transfer material from a specific image forming unit (for example, the image forming unit d located at the most downstream in the moving direction of the transfer belt), and a full color image is formed below. A monochromatic image is obtained through the same process as in the case.
A pair of registration sensors (CCD or an optical sensor composed of an LED light emitting part and a photosensor light receiving part) 60 is provided on both sides of the transfer belt 71 and formed on the transfer belt 71 by each image forming part. A registration pattern (color misregistration detection pattern shown in FIG. 3) is detected.
[0107]
When the image forming apparatus of the present invention enters the auto registration mode, the controller 1000 (the above-described control unit) performs registration correction by feeding back the image of the registration pattern of each image forming unit to the read image by the registration sensor 60 serving as a detection unit. Like the first embodiment, the controller shown in FIG.
[0108]
The auto registration pattern of the present embodiment is as shown in FIG. 3 as in the first embodiment. The registration pattern is written on the transfer belt 71 in each image forming unit, and the position of the registration pattern is registered with the registration sensor. Detect by 60.
[0109]
Thus, auto registration (automatic registration correction processing) is performed by adjusting the timing of image writing, the magnification, and the inclination of the image.
[0110]
Hereinafter, an auto registration routine (normal registration correction processing) of the image forming apparatus according to the present embodiment will be described with reference to FIG. Note that this normal registration correction processing is performed when the image forming apparatus is powered on and then left for a predetermined time.
[0111]
The normal registration correction processing is completely the same as that of the first embodiment except that the registration deviation detection performed on the intermediate transfer belt 31 in the first embodiment is performed on the transfer belt 71. It is the same.
[0112]
First, the registration patterns 90Y, 90M, 90C, and 90BK are transferred onto the transfer belt 71 by each color image forming unit, the position of the registration pattern transferred onto the transfer belt 71 is detected by the registration sensor 60, and the reference black ( (BK) A distance L1 of the registration pattern 90BK and a distance L2 of the registration pattern (90Y, 90M, 90C) of the next image forming unit (yellow (Y), magenta (M), cyan (C)) are calculated, and L1, L2 , And L2 image data (yellow (Y) image data, magenta (M) image data, cyan (C) image data) are controlled so that L1 = L2 and the magnification of the image is adjusted.
[0113]
Next, in order to perform the image writing position (writing in the main scanning direction, left correction), the writing position in the main scanning direction is moved so that ΔH becomes “0”.
[0114]
Thereafter, the image of the registration pattern corrected for magnification and image writing is written on the transfer belt 71 by each image forming unit.
[0115]
Next, the inclination of the image is corrected.
[0116]
This is achieved by matching the distance ΔV1 with the distance ΔV1 and the registration pattern (black registration pattern 90BK) of the image forming unit serving as a reference.
[0117]
Finally, in order to align the leading edge position of the image, ΔV1 is adjusted to be a predetermined distance X, for example, the interval between the image forming portions.
[0118]
Also, registration patterns 90Y, 90M, 90C, and 90BK are written on the transfer belt 71 and checked by the registration sensor 60.
[0119]
If the registration (registration) is not correct, this routine is repeated several times to perform image alignment and increase the accuracy.
[0120]
Next, registration correction processing when a predetermined number of images have elapsed in continuous image formation will be described. Note that the registration correction processing when a predetermined number of sheets have elapsed in this continuous image formation is also performed except that the registration deviation detection performed on the intermediate transfer belt 31 in the first embodiment is performed on the transfer belt 71. This is exactly the same as in the first embodiment.
[0121]
Due to the temperature rise in the apparatus due to the continuous image formation, the image shift occurs due to the influence of the distortion on the optical components of the image writing unit such as a laser scanner. In order to prevent this, image correction is performed when a predetermined number of images are continuously formed. The image correction performed at this time is dominated by a temperature rise and has a large amount of deviation, leading edge deviation (image writing position deviation in the sub-scanning direction) and image writing position deviation (image writing position deviation in the main scanning direction). Only the correction is performed.
[0122]
The interval between the registration patterns in this mode is set to “1 / n” (n: integer) of the predetermined distance X adjusted when aligning the image leading end position in the normal registration correction process.
[0123]
The registration pattern in this mode is performed in one image frame during the above-described continuous image formation, and is written so that ΔH becomes “0” in order to perform the image writing position (writing in the main scanning direction, left correction). Move position.
[0124]
Next, ΔV1 is adjusted to be “1 / n” of the predetermined distance X in order to align the front end position of the image, and the correction process is terminated.
[0125]
Thus, registration can be performed simply, images can be aligned, and the auto registration mode can be set in a short time (automatic registration correction is performed).
[0126]
It should be noted that the registration correction process when a predetermined number of sheets have elapsed in this continuous image formation is also performed at the restart after the jam process.
[0127]
Through the above processing, during continuous image formation, only the registration correction for the main scanning and sub-scanning writing is simply applied to shorten the time for image correction that occurs during continuous image formation, shorten the down mode, and increase productivity. As the image quality increases, it is possible to provide good image quality.
[0128]
In the first and second embodiments, the example of detecting the registration deviation on the intermediate transfer belt and the transfer belt has been described. However, the present invention is not limited to the intermediate transfer belt and the transfer belt. The present invention can be implemented in any configuration as long as it is possible to detect a deviation in the alignment.
[0129]
As described above, during continuous image formation, by simply performing only registration correction for writing in the main scanning direction and sub-scanning direction, the time required for image correction that occurs during continuous image formation can be shortened and the down mode can be shortened. .
[0130]
The configuration of a data processing program that can be read by the image forming apparatus according to the present invention will be described below with reference to the memory map shown in FIG.
[0131]
FIG. 9 is a diagram illustrating a memory map of a storage medium that stores various data processing programs that can be read by the image forming apparatus according to the present invention.
[0132]
Although not particularly illustrated, information for managing a program group stored in the storage medium, for example, version information, creator, etc. is also stored, and information depending on the OS on the program reading side, for example, a program is identified and displayed. Icons may also be stored.
[0133]
Further, data depending on various programs is also managed in the directory. In addition, when a program or data to be installed is compressed, a program to be decompressed may be stored.
[0134]
The functions shown in FIGS. 5, 6, and 7 in this embodiment may be performed by a host computer by a program installed from the outside. In this case, the present invention is applied even when an information group including a program is supplied to the output device from a storage medium such as a CD-ROM, flash memory, or FD, or from an external storage medium via a network. Is.
[0135]
As described above, a storage medium storing software program codes for realizing the functions of the above-described embodiments is supplied to the system or apparatus, and the computer (or CPU or MPU) of the system or apparatus stores the storage medium in the storage medium. It goes without saying that the object of the present invention can also be achieved by reading and executing the programmed program code.
[0136]
In this case, the program code itself read from the storage medium realizes the novel function of the present invention, and the storage medium storing the program code constitutes the present invention.
[0137]
Examples of the storage medium for supplying the program code include a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, DVD-ROM, magnetic tape, nonvolatile memory card, ROM, EEPROM, A silicon disk or the like can be used.
[0138]
Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (operating system) or the like running on the computer based on the instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included.
[0139]
Further, after the program code read from the storage medium is written to a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. It goes without saying that the case where the CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.
[0140]
Further, the present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device. Needless to say, the present invention can be applied to a case where the present invention is achieved by supplying a program to a system or apparatus. In this case, by reading the storage medium storing the program represented by the software for achieving the present invention into the system or apparatus, the system or apparatus can enjoy the effects of the present invention. .
[0141]
Furthermore, by downloading and reading a program represented by software for achieving the present invention from a database on a network by a communication program, the system or apparatus can enjoy the effects of the present invention. .
[0142]
【The invention's effect】
As described above, according to the present invention, the processing time required for image correction during continuous image formation can be shortened, and a good color image can be obtained without reducing the productivity.
[0144]
Therefore, it is possible to simply perform correction only on correction items affected by the operation state of the image forming unit, prevent delay due to image correction due to image correction, and always provide a high-quality image at high speed. There are effects such as being able to.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a configuration of an intermediate transfer type image forming apparatus to which an image forming apparatus according to a first embodiment of the present invention can be applied.
FIG. 2 is a block diagram illustrating a configuration of a controller provided in the control board shown in FIG.
FIG. 3 is a schematic diagram illustrating an auto registration pattern of the image forming apparatus of the present invention.
FIG. 4 is a schematic diagram of a registration pattern for explaining an auto registration process of the image forming apparatus of the present invention.
FIG. 5 is a flowchart illustrating an example of registration correction processing of the image forming apparatus of the present invention.
FIG. 6 is a flowchart illustrating a registration correction processing procedure in a first image alignment mode (an image alignment mode in which correction items are fully executed) of the image forming apparatus of the present invention.
FIG. 7 is a flowchart illustrating a registration correction processing procedure in a second image alignment mode (image alignment mode in which correction items to be executed are limited) of the image forming apparatus of the present invention.
FIG. 8 is a cross-sectional view illustrating the configuration of an image forming apparatus showing a second embodiment of the invention.
FIG. 9 is a diagram illustrating a memory map of a storage medium that stores various data processing programs that can be read by the image forming apparatus according to the present invention.
[Explanation of symbols]
ad station
10 Image forming unit
11a to 11d Photosensitive drum
31 Intermediate transfer belt
60 cash register sensor
71 Transfer belt
1018 CPU
1024 ROM
1025 RAM

Claims (3)

A toner image is formed on each of a plurality of image carriers using toner of each color included in each of a plurality of image forming units, and the toner images formed on each of the plurality of image carriers are transferred onto a recording medium via an intermediate transfer member. In an image forming apparatus that forms a color image by transferring to
Pattern forming means for causing the image forming unit to form the predetermined toner pattern on each of the plurality of image carriers in order to form a predetermined toner pattern corresponding to each of a plurality of colors of toner on the intermediate transfer member; ,
Detecting means for detecting a formation position of the predetermined toner pattern transferred onto the intermediate transfer member;
Based on the detection result of the detection unit, the toner image formation position of each of the plurality of colors in the conveyance direction of the recording medium and the direction orthogonal to the conveyance direction, the inclination of the toner image with respect to the direction orthogonal to the conveyance direction, And a first correction for correcting the magnification of the toner image, and a second correction for correcting the formation positions of the toner images of the plurality of colors in the transport direction of the recording medium and in the direction orthogonal to the transport direction. Correction means to perform,
Wherein the correction means, when the power of the image forming apparatus is turned on, or executes the first correction when the lapse of a predetermined time with no be imaged from the power supply is turned on, a continuous by the image forming section executing the second correction when the image forming the image from the start to a predetermined number of recording media are formed,
When performing the first correction, the correction unit repeats the first correction until the formation position of the predetermined toner pattern detected by the detection unit falls within a predetermined range, and the second correction The image forming apparatus is characterized in that the second correction is not repeated when performing the above. A toner image is formed on each of a plurality of image carriers using toner of each color included in each of a plurality of image forming units, and the toner images formed on each of the plurality of image carriers are conveyed on a recording medium conveyed by a transfer belt. In an image forming apparatus for forming a color image by directly transferring to
Pattern forming means for forming the predetermined toner pattern on each of the plurality of image carriers on the image forming unit in order to form a predetermined toner pattern corresponding to each of a plurality of colors of toner on the transfer belt;
Detecting means for detecting a formation position of the predetermined toner pattern transferred onto the transfer belt;
Based on the detection result of the detection unit, the toner image formation position of each of the plurality of colors in the conveyance direction of the recording medium and the direction orthogonal to the conveyance direction, the inclination of the toner image with respect to the direction orthogonal to the conveyance direction, And a first correction for correcting the magnification of the toner image, and a second correction for correcting the formation positions of the toner images of the plurality of colors in the transport direction of the recording medium and in the direction orthogonal to the transport direction. Correction means to perform,
Wherein the correction means, when the power of the image forming apparatus is turned on, or executes the first correction when the lapse of a predetermined time with no be imaged from the power supply is turned on, a continuous by the image forming section executing the second correction when the image forming the image from the start to a predetermined number of recording media are formed,
When performing the first correction, the correction unit repeats the first correction until the formation position of the predetermined toner pattern detected by the detection unit falls within a predetermined range, and the second correction The image forming apparatus is characterized in that the second correction is not repeated when performing the above.   3. The image forming apparatus according to claim 1, wherein the correction unit performs the second correction prior to image formation after jam processing of the recording medium. 4.

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