JP2010210800A - Image forming apparatus, alignment correction method, and alignment correction control program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To output a high quality image without any misalignment without incurring toner consumption due to creation of an unnecessary pattern and execution of an unnecessary aligning action. <P>SOLUTION: Main scanning magnification correction and sub scanning magnification correction are carried out between pages that are continuously printed and when a correction result by the main scanning magnification correction exceeds a preset threshold (step S104-Yes) and at the same time the correction result by the sub scanning magnification correction exceeds a preset threshold (step S105-Yes), the continuous printing is interrupted and the correction for alignment is executed by the main scanning magnification correction and the sub scanning magnification correction (step S106) when the misalignment in the image is corrected based on the amount of misalignment detected by a misalignment detection means. At that time, the main scanning magnification correction is executed based on detection results by a first and a second synchronizing detection sensors and the sub scanning magnification correction is executed based on the detection results of the first synchronizing detection sensor and a non-parallel PD. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a copying machine, a printer, a facsimile having a function of detecting and correcting a positional deviation of each color image of a color image created by superimposing a plurality of color images, and a digital having these functions combined. The present invention relates to an image forming apparatus such as a multifunction machine, an alignment correction method performed in accordance with the positional deviation correction performed in the image forming apparatus, and a computer program for executing the alignment correction method by a computer.

  In a color image forming apparatus that forms a multi-color image, unlike a black and white image, the images of each color are overlapped. Therefore, if the image position of each color is shifted, the color of the line drawing or character changes, or the color shift or image unevenness occurs. (Color unevenness) occurs. The occurrence of such deviation and unevenness leads to a decrease in image quality. Therefore, it is necessary to match the image positions of the respective colors as much as possible. For this reason, in an image forming apparatus that forms a color image using a plurality of photoconductors, there is a technique for correcting a positional shift between colors caused by various factors, such as a change in environmental temperature and a change in internal temperature. It is disclosed in Patent Documents 1 to 3.

  Among them, Patent Document 1 (Japanese Patent Laid-Open No. 2004-295083) discloses an LD unit that is controlled to be turned on according to image data and a pixel clock that variably controls the phase of a lighting control clock (hereinafter referred to as a pixel clock) of the LD unit. In a light beam writing apparatus that has a generation unit and performs writing by scanning a light beam output from an LD unit on an image carrier that rotates or moves in the sub-scanning direction, the pixel clock generation unit includes a pixel clock The image magnification in the main scanning direction on the image carrier is corrected by changing the phase of the image at one or a plurality of positions in the main scanning direction in units of 1 / n of one pixel clock cycle (n is an integer of 2 or more). Is disclosed.

  Patent Document 2 (Japanese Patent Application Laid-Open No. 2003-149905) includes a plurality of image forming units that form images having different colors, and images having different colors formed by the plurality of image forming units. In a color image forming apparatus that forms a color image by transferring it onto a recording medium directly or via an intermediate transfer member, the registration error detection pattern formed by each image forming unit is the same pattern detection member. A registration error correction operation executing means for detecting a registration error detection pattern transferred onto the pattern detection member and executing a registration error correction operation; and a registration error by the registration error correction operation executing means. Start condition setting means that can arbitrarily set the start condition of the correction operation.The registration deviation correction operation execution condition is set to low power when the power is turned on. The amount of change from the temperature of the return from the mode, or is disclosed to be determined by the number of printed sheets after the correction operation performed last.

  Further, in Patent Document 3 (Japanese Patent Application Laid-Open No. 2007-212873), an image formed by a plurality of image forming units installed along a conveyance body is sequentially superimposed and transferred onto a recording medium. In a color image forming apparatus that obtains an image, a first light detection unit and a second light detection unit that perform alignment in the main scanning direction are provided, and an operation between the first light detection unit and the second light detection unit is performed. Counting means for counting time is provided, the count value from the counting means is taken in, the count value acquired at the start of printing is compared with the count value acquired between pages, and when the comparison result exceeds a predetermined threshold value It is disclosed that alignment can be executed in an optimal state by sending an alignment request and detecting an optimal alignment time.

  By the way, as for the timing for executing misregistration correction during printing, since the timing that requires correction was predicted by using the number of printed sheets and the amount of change in temperature, actual misregistration correction is not required. Even in such a case, the correction is performed, or the situation in which the correction cannot be executed even at a necessary timing has occurred.

  Therefore, in the invention described in Patent Document 3, a misregistration pattern for detecting a misregistration correction amount is created outside the image area, and the misregistration amount is detected and corrected by measuring the misregistration pattern. Although a method has been proposed, there is a problem that toner is consumed in addition to image output.

  On the other hand, in the invention described in Patent Document 1, the time between the first light detection means and the second light detection means is counted between continuously printed sheets, and the phase of the writing frequency is changed to change the main frequency. Although it is disclosed that the scanning magnification is corrected, and the invention described in Patent Document 2 describes that the execution condition of the registration error correction operation is set, the setting of the position error correction timing is not particularly mentioned. In addition, depending on the frequency of correction timing, unnecessary consumption of toner becomes a problem as in the invention described in Patent Document 3.

  Therefore, the problem to be solved by the present invention is to output a high-quality image without misalignment without executing toner consumption due to unnecessary pattern generation and unnecessary alignment operation.

  The problems include an image forming unit that forms a multicolor image by superimposing a plurality of single color images, a pattern forming unit that forms a misregistration correction pattern between adjacent single color image forming sections, and the formed position. A misregistration detection unit that optically reads a misregistration correction pattern and detects a misregistration amount; and a correction unit that corrects the misregistration of the image based on the misregistration amount detected by the misregistration detection unit. In the image forming apparatus, the correction unit includes a main scanning magnification correction unit that performs main scanning magnification correction between pages during continuous printing, and a sub scanning magnification correction unit that performs sub scanning magnification correction, and the correction unit includes: When the correction result of the main scanning magnification correction means or the sub scanning magnification correction means exceeds a preset threshold value, continuous printing is interrupted and the main scanning magnification correction means and the sub scanning magnification correction means And executes alignment correction.

  The second means further comprises holding means for holding the correction result in the first means, and the main scanning magnification correction means is located outside the image forming area on the front end side and the rear end side of the image forming area. A first and a second light detecting means for detecting a scanned light beam and outputting a synchronization detection signal, respectively, and a first synchronization detection signal output of the first light detection means for outputting the second light detection means; First counting means for counting a first time until the second synchronization detection signal is output from the light detecting means, and obtaining an alignment correction amount for main scanning based on the counted first time. The main scanning magnification is corrected, and the sub-scanning magnification correcting means is provided on the downstream side in the light scanning direction of the first light detecting means in a non-parallel manner with respect to the first light detecting means and scanned light. Third optical detection that detects the beam and outputs a synchronization detection signal And a second counting means for counting a second time from the synchronization detection signal output of the first light detection means to the synchronization detection signal output of the third light detection means. A sub-scanning alignment correction amount is obtained based on the second time to correct a sub-scanning magnification, and the holding unit holds the main-scan and sub-scan alignment correction amounts.

  The third means is the second means, wherein the holding means holds the alignment correction amount in the main scanning direction from the start of correction, and the main scanning correction amount is the correction amount from the start of alignment correction. It is characterized by that.

  The fourth means further comprises third counting means for counting the number of continuous prints in any of the first to third means, and the number of continuous prints is preset according to the count result of the third count means. If the measured threshold value is exceeded, continuous printing is interrupted and alignment is executed.

  The fifth means includes a temperature detecting means for detecting the ambient temperature in any one of the first to fourth means, and a comparing means for comparing the temperature at the start of continuous printing and the temperature at the time of obtaining the inter-page count value. , And when the temperature difference exceeds a preset threshold value according to the comparison result of the comparison means, the continuous printing is interrupted and the alignment is executed.

  The sixth means includes the image forming means for forming a multicolor image by superimposing a plurality of single color images, the pattern forming means for forming a misregistration correction pattern between adjacent single color image forming sections, and the above-described formation. A misregistration detection unit that optically reads the misregistration correction pattern and detects a misregistration amount; a correction unit that corrects misregistration of an image based on the misregistration amount detected by the misregistration detection unit; An alignment correction method of an image forming apparatus that performs alignment correction for main scanning and sub-scanning at a predetermined timing, and executes main-scanning magnification correction and sub-scanning magnification correction between pages during continuous printing, When the main scanning magnification correction result or the sub-scanning magnification correction result exceeds a preset threshold value, continuous printing is interrupted and alignment correction by the main scanning magnification correction and the sub-scanning magnification correction is performed. Characterized in that it.

  The seventh means includes the image forming means for forming a multicolor image by superimposing a plurality of single color images, the pattern forming means for forming a misregistration correction pattern between adjacent single color image forming sections, A misregistration detection unit that optically reads the misregistration correction pattern and detects a misregistration amount; a correction unit that corrects misregistration of an image based on the misregistration amount detected by the misregistration detection unit; And an alignment correction control program for an image forming apparatus for executing alignment correction control for main scanning and sub-scanning at a predetermined timing by a computer. When the scanning magnification correction is executed and the main scanning magnification correction result or the sub-scanning magnification correction result exceeds a preset threshold, continuous printing is interrupted and the main running Characterized in that it comprises a step of performing a position alignment correction according to magnification correction and subscanning magnification correction, the.

  In the embodiments described later, the image forming unit is the image forming unit 1, the pattern forming unit is the image forming unit 1 and the system controller 201, the misregistration correction patterns are denoted by reference numerals 21 and 22, and the misregistration detecting unit is the first. The first and second misregistration detection sensors 14 and 15 and the alignment controller 203, the correction means to the alignment controller 203 and the system controller 201, the holding means to the RAM 20, and the first and second counting means to the alignment. The counter in the controller 203, the third counting means corresponds to the printed sheet counter 17, the temperature detecting means corresponds to the temperature sensor 18, and the comparing means corresponds to the system controller 201.

  According to the present invention, since the alignment correction control is executed when the correction result of the main scanning magnification correction or the sub scanning magnification correction exceeds a preset threshold value, toner consumption due to unnecessary pattern creation and unnecessary Therefore, it is possible to output a high-quality image without a position shift without executing a proper alignment operation.

1 is a schematic configuration diagram illustrating a configuration of a main part of a color image forming apparatus of Example 1 according to an embodiment of the present invention. FIG. 2 is a perspective view showing a main part in FIG. 1, here a conveying belt and a photosensitive drum. 6 is a diagram illustrating a detection configuration of a misregistration detection pattern in Embodiment 1. FIG. FIG. 2 is a diagram illustrating a schematic configuration of an image formation control unit in the image forming apparatus according to the first exemplary embodiment. It is a figure which shows roughly the structure of the synchronous detection part in Example 1, and the output timing of a detection output. FIG. 3 is a block diagram illustrating a circuit configuration of a misalignment correction circuit according to the first exemplary embodiment. 6 is a flowchart illustrating a processing procedure in the first to third embodiments. 10 is a flowchart illustrating a processing procedure in the fourth embodiment. 14 is a flowchart illustrating a processing procedure when a positioning execution request is received in the fifth embodiment. 15 is a flowchart illustrating a processing procedure when user selection is performed in the sixth embodiment.

  The present invention determines whether or not alignment is necessary based on the main scanning magnification correction amount during printing and the sub-scan correction amount at the synchronization position, and enables alignment to be executed at an appropriate timing. As a result, unnecessary consumption of toner due to unnecessary pattern generation and unnecessary alignment operation can be avoided, and a high-quality image free from misalignment can be output.

  Hereinafter, examples according to embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram illustrating a configuration of a main part of a color image forming apparatus according to Example 1 of the present embodiment. This color image forming apparatus is a so-called direct transfer tandem color image forming apparatus. In the following description, Y, M, C, and K added after the reference numerals shown in the figure correspond to the colors yellow, magenta, cyan, and black, respectively. The subscript indicating is omitted.

  The image forming apparatus PR includes four image forming units 1 that form different colors, that is, a first station (Y) 1Y, a second station (M) 1M, a third station (C) 1C, and a fourth station ( K) 1K is provided, and each of these stations 1Y, 1M, 1C, and 1K is arranged along a straight line along the conveying belt 8. Each image forming unit 1 is arranged around a photosensitive drum 2 that functions as an image forming medium, the photosensitive drum 2, and includes a charging device 3, an exposure device 4, a developing device 5, and a cleaning device 6. .

  The conveyor belt 8 is rotationally driven in the direction of arrow A by a roller 9 provided as one drive roller and the other as a driven roller. The surface of the photosensitive drum 2 is uniformly charged by the charging device 3 and then exposed by a pattern corresponding to an image to be output by the exposure device 4, and an electrostatic latent image is formed on the surface of the photosensitive drum 2. The The electrostatic latent image formed on each photoconductor drum 2 is developed by the developing device 5, and a toner image of each color is formed on each photoconductor drum 2.

  The recording paper 10 is fed out from the paper feed tray 11 and is conveyed by the conveyor belt 8 to the first station (Y) 1Y, the second station (M) 1M, the third station (C) 1C, and the fourth station (K). 1K is sequentially passed, and the respective color toner images formed on the respective photosensitive drums 2 at the respective transfer positions 7 are sequentially transferred and superimposed on the same position of the recording paper 10. In this way, one full-color image is obtained by superimposing four-color images. The recording paper 10 to which the four color toner images have been transferred is peeled off from the conveying belt 8, fixed by the fixing device 12, and discharged outside the apparatus.

  The toner remaining on the surface of the photosensitive drum 2 after the transfer of the color toner images formed on the photosensitive drums 2 is removed by the cleaning device 6 to prepare for the next image forming cycle. This type of image forming apparatus is referred to as a direct transfer type tandem type image forming apparatus because the image on the photosensitive drum 2 is directly transferred to the recording paper 10.

  FIG. 2 is a perspective view showing the main part in FIG. 1, here the conveying belt 8 and the photosensitive drum 2. 2, the arrow B indicates the main scanning direction orthogonal to the moving direction of the conveying belt 8, and the arrow C indicates the sub-scanning direction parallel to the moving direction of the conveying belt 8. ing.

  FIG. 3 is a diagram showing a detection configuration of a misregistration detection pattern. FIG. 3 is obtained by adding a configuration in which a detection pattern is formed on the conveyor belt 8 and the detection pattern is optically detected by a detection device. A first and second light-reflective sensor composed of a light-emitting part and a light-receiving part is formed on each of the photosensitive drums 2 on the conveying belt 8 by forming misregistration detection patterns 21 and 22 at two places in the main scanning direction. The position deviation detection sensors 14 and 15 detect the analog signals, and convert the detected analog signals into digital signals by an A / D converter to obtain voltage values. An alignment controller 203 (to be described later) calculates the position of the position shift detection pattern from the acquired voltage value, and calculates a position shift correction amount. The image after the positional deviation correction amount calculation is formed by reflecting the newly calculated correction amount. The misregistration detection patterns 21 and 22 are formed when the image forming unit 1 writes a pattern composed of a single single color line between sheets according to an instruction from the system controller 201. The length and width of the pattern are arbitrary, and are determined in consideration of the resolution of the position shift detection sensors 14 and 15 and the amount of consumed toner.

  FIG. 4 is a schematic configuration diagram of an image formation control unit in the image forming apparatus, and shows a light beam scanning device and an optical unit in addition to the image formation control unit. The light beam scanning device is the exposure device 4 shown in FIG. 1, and in this embodiment, the surface of the photosensitive drum 2 is scanned and written with laser light.

  The light beam scanning device 4 includes a front-end synchronization detection plate 44F and a rear-end synchronization detection plate 44B that detect a light beam at both ends in the main scanning direction, and the light beam transmitted through the fθ lens 43 is the first and second mirrors 46−. 1, 46-2 and condensed by the first and second lenses 45-1 and 45-2, and is incident on the front-end synchronization detection plate 44F and the rear-end synchronization detection plate 44B.

  The image formation control unit includes a system controller 201, a pixel clock generation unit 202, an alignment controller 203, a synchronization detection lighting control unit 204, an LD control unit 205, and a polygon motor drive control unit 206. There is one system controller 201 for a plurality of colors, but the other system controller 201 has the same one for each of the plurality of colors. The pixel clock generator 202 further includes a reference clock generator 2021, a VCO (Voltage Controlled Oscillator) clock generator 2022, and a phase-synchronized clock generator 2023. Further, as described above, the tip synchronization detection plate 44F that detects the light beam on the image writing side at the end portion in the main scanning direction of the light beam scanning device 4 detects the light beam on the end side of the image writing at the end portion in the main scanning direction. A rear end synchronization detection plate 44B is provided, and when the light beam transmitted through the fθ lens 123 passes through the front end synchronization detection plate 44F and the rear end synchronization detection plate 44B as described above, the first end as described later. The light enters the synchronization detection sensor 44-1, the non-parallel PD 44-3, and the second synchronization detection sensor 44-2, and the alignment controller 203 starts from the first synchronization sensor 44-1 and the non-parallel PD 44-3. The synchronization detection signal XDETP and the end-side synchronization detection signal XEDETP are input from the second synchronization sensor 44-2, respectively.

  The synchronization detection signal XDETP output from the first synchronization detection sensor 44-1 and the non-parallel PD 44-3 is input to the pixel clock generation unit 202, the synchronization detection lighting control unit 204, and the alignment controller 203, respectively. The pixel clock generation unit 202 generates a pixel clock PCLK that is synchronized with the synchronization detection signal XDETP, and sends it to the LD control unit 205 and the synchronization detection lighting control unit 204.

  The pixel clock generation unit 202 includes a reference clock generation unit 2021, a VCO (Voltage Controlled Oscillator) clock generation unit 2022, and a phase synchronization clock generation unit 2023.

  A VCO clock generation unit (PLL circuit: Phase Locked Loop) 2022 inputs a reference clock signal FREF from the reference clock generation unit 2021 and a signal obtained by dividing VCLK by N by a 1 / N divider 20221 to a phase comparator 20222. The phase comparator 20222 compares the falling edges of both signals and outputs an error component at a constant current. Then, unnecessary high-frequency components and noise are removed by an LPF (low-pass filter) and sent to the VCO. The VCO outputs an oscillation frequency that depends on the output of the LPF. Accordingly, the frequency of VCLK can be changed by variably controlling the frequency of FREF and the frequency division ratio N from the printer control unit 201. The phase synchronization clock generation unit 2023 generates a pixel clock PCLK synchronized with the synchronization detection signal XDETP from the VCLK generated by the VCO clock generation unit 2022.

  Further, the end-side synchronization detection signal XEDETP output from the second synchronization detection sensor 44-2 is input to the alignment controller 203. The alignment controller 203 measures the time from the falling edge of the start side synchronization detection signal XDETP to the falling edge of the end side synchronization detection signal XEDETP, compares it with the reference time difference, and changes the pixel clock frequency by the difference. Correct the image magnification.

  The synchronization detection lighting control unit 204 first turns on the LD forced lighting signal BD to forcibly light the LD in order to detect the synchronization detection signal XDETP. However, after detecting the synchronization detection signal XDETP, the synchronization detection signal XDETP is detected. Using the XDETP and the pixel clock PCLK, the LD is turned on at a timing at which the synchronization detection signal XDETP can be reliably detected without causing flare light, and the LD is turned off when the synchronization detection signal XDETP is detected. A signal BD is generated and sent to the LD control unit 205.

  The LD control unit 205 controls the lighting of the LD according to the image data synchronized with the synchronous detection forced lighting signal BD and the pixel clock PCLK. Then, a laser beam is emitted from the LD unit 42, reflected and deflected by the mirror surface of the polygon mirror 41, passes through the fθ lens 43, and scans on the photoreceptor 40.

  The polygon motor control unit 206 controls rotation of the polygon motor that rotationally drives the polygon mirror 41 at a specified number of rotations based on a control signal from the printer control unit 201.

  The first and second misregistration detection sensors 14 and 15 for detecting the image misregistration correction pattern are light reflection type optical sensors, and image pattern information detected by the sensors 14 and 15 is sent to the system controller 201. Sent. The system controller 201 calculates a positional deviation amount based on the image pattern information 21 and 22, generates correction data, and stores it in a correction data storage unit (not shown). The correction data storage unit stores correction data for correcting image position deviation and magnification deviation, that is, data for determining the timing of the XLGATE and XFGATE signals, and data for determining the frequency of the pixel clock PCLK. In accordance with an instruction from 201, correction data is set in each control unit.

  FIG. 5 is a diagram schematically showing the configuration of the synchronization detection unit and the output timing of the detection output. The synchronization detection unit includes a front-end synchronization detection plate 44F and a rear-end synchronization detection plate 44B. A first synchronization detection sensor 44-1 and a non-parallel PD 44-3 installed non-parallel to the first synchronization detection sensor 44-1 are mounted on the tip synchronization detection plate 44F. When the light beam passes through the first synchronization detection sensor 44-1 and the non-parallel PD 44-3, the synchronization detection signal (XDETP) is output twice. Therefore, at the timing shown in FIG. 5, by measuring the interval between the fall timing of the first synchronization detection sensor 44-1 and the fall timing of the second synchronization detection sensor 44-2, the main scanning magnification, and The variation between the polygonal faces can be detected, and the difference between the falling timing of the detection signal of the first synchronization detection sensor 44-1 of the tip synchronization detection plate 44F and the falling timing of the detection signal of the non-parallel PD 44-3 is measured. Accordingly, the shift of the sub-scanning resist can be detected. That is, if the light beam is scanning a certain position, the time that is output twice from the tip synchronization detection plate 44F is constant, but this time interval changes means that the scanning position of the light beam is shifted. Therefore, since the deviation of the scanning position appears as a sub-scanning registration deviation amount, the sub-scanning image formation timing is changed according to the detected sub-scanning deviation amount.

  FIG. 6 is a block diagram showing a circuit configuration of the positional deviation correction circuit. In the figure, the misregistration correction circuit is mainly composed of the alignment controller 203 and the system controller 201 also shown in FIG. The alignment controller 203 is supplied with an output from the converter 16 that performs A / D conversion on outputs from the misalignment detection sensors (detectors) 14 and 15 and a write start signal for each page. A printing sheet counter 17 is connected to the alignment controller 203 and the system controller 201 so that signals can be transmitted and received between them, and the detection output of the temperature sensor 18 is input to the alignment controller 203. As a result, the count value of the printed sheet counter 17 and the temperature detected by the temperature sensor 18 are input to the alignment controller 208.

  The alignment controller 203 is connected to the ROM 19 and the RAM 20, and the ROM 19 stores a program used by a CPU (not shown) of the alignment controller 203. The CPU stores the RAM 20 in a work area and a work area for executing the program. Used as a data buffer to execute alignment correction control (magnification correction). Therefore, the alignment controller 203 executes alignment correction and positional deviation correction according to the program. Similarly to the alignment controller 203, the system controller 201 also includes a CPU (not shown). The CPU reads a program stored in a ROM (not shown) and uses a RAM (not shown) as a work area and a data buffer for executing the program. Then, an instruction related to alignment and an instruction related to image formation are given to the alignment controller 203, and in cooperation with each other, positional deviation correction control, alignment correction control, and control of each part of the engine are executed.

FIG. 7 is a flowchart illustrating a processing procedure (correction procedure for magnification correction) in the first embodiment.
In the figure, the alignment controller 203 clears the main scanning magnification correction amount Xs to 0 when executing correction at the start of printing (step S101-Yes), and the first synchronization detection sensor 44 of the synchronization detection signal (XDETP) at that time. −1, the output interval Yds of the non-parallel PD 44-3 is stored (step S102).

  The system controller 201 requests the alignment controller 203 to execute inter-page correction between pages during continuous printing (No in step S101). Upon receiving the inter-page correction execution request, the alignment controller 203 executes main scanning magnification correction and sub-scanning position correction, adds the main scanning magnification correction amount to Xs, and outputs the print start output interval Yds and the current output interval. The difference between Ydd and Ydd is stored (step S103), the added main scanning magnification correction amount Xs is greater than or equal to a preset threshold value Xt (step S104-Yes), and the output interval difference Ydd is greater than or equal to Ydt (step If (S105-Yes), the system controller 201 is requested to execute alignment (step S106).

  Upon receiving the alignment execution request, the system controller 201 temporarily stops printing, executes alignment, and resumes printing after completion of alignment.

  In the flowchart of FIG. 7, the alignment execution request is transmitted in step S106 when the main scanning magnification correction amount is greater than or equal to the threshold value Xt and the sub-scanning magnification correction amount is greater than or equal to the threshold value Ydt in steps S104 and S105. The positioning execution request may be transmitted when any one of the correction amounts exceeds a threshold value.

  In this embodiment, the direct transfer type tandem image forming apparatus is illustrated in FIG. 1, but a YMCK full-color image is once transferred to an intermediate transfer belt, and then an image superimposed with four colors on a recording sheet is displayed. The same applies to an indirect transfer tandem type image forming apparatus that performs batch transfer.

  As described above, according to the present embodiment, since the execution condition of the positional deviation correction is determined based on the main scanning magnification correction amount and the sub-scanning positional deviation amount of the synchronization position, the positional deviation detection pattern is set between the sheets. No need to create. As a result, toner consumption other than image output can be reduced, and it is possible to perform alignment during continuous printing before a significant shift, and a high-quality printed image without misalignment can be output.

  In the first exemplary embodiment, the synchronization detection detection time of the first synchronization detection sensor 44-1 and the second synchronization detection sensor 44-2 is counted between pages for continuous printing, and correction of misalignment in main scanning (hereinafter, “ In the second embodiment, the print number counter 17 is incremented every time printing is completed, and main-scanning positional deviation correction is executed based on the counted number of sheets. The mechanical configuration of the color image forming apparatus and the electrical configuration including the control configuration are the same as those in the first embodiment, and a duplicate description is omitted. Further, the processing procedure in the second embodiment is also the same as that in the first embodiment.

  In the second embodiment, the system controller 201 counts up the print number counter 17 every time printing is completed. The alignment controller 203 clears the main scanning magnification correction amount Xs to 0 when correction is performed at the start of printing (step S101—Yes), and the first synchronization detection sensor 44-1 of the synchronization detection signal (XDETP) at that time, non- The parallel PD output interval Yds is stored, and at the same time, the count value Ps of the printed sheet counter 17 is stored (step S102).

  The system controller 201 requests the alignment controller 45 to execute inter-page correction between pages during continuous printing (step S101—No). In response to the inter-page correction execution request, the alignment controller 203 executes main scanning magnification correction and sub-scanning position correction, adds the main scanning magnification correction amount to Xs, and outputs the print start output interval Yds and the current output interval. The difference between Ydd and Ydd is stored (step S103), the added main scanning magnification correction amount Xs is greater than or equal to a preset threshold value Xt (step S104-Yes), and the output interval difference Ydd is greater than or equal to Ydt (step (S105-Yes), the count value Pp of the printed sheet counter 17 is acquired, and when the difference between Pp and Ps is greater than or equal to a preset threshold value Pt, the system controller 201 is requested to execute alignment. (Step S106).

  Upon receiving the alignment execution request, the system controller 201 temporarily stops printing, executes alignment, and resumes printing after completion of alignment.

  Other parts not specifically described are configured in the same manner as in the first embodiment and function in the same manner.

  According to the present embodiment, the condition for performing misalignment correction is determined by combining the main scanning magnification correction amount and the sub-scanning position misalignment amount of the synchronization position with the number of continuous prints, so that the number of alignment executions can be reduced. Thus, productivity can be improved while maintaining print quality.

  In the first embodiment, the main scanning misalignment correction is executed based on the detection time of synchronization detection between pages in continuous printing. In the second embodiment, the main scanning misalignment correction is executed based on the count value of the number of printed sheets. However, the third embodiment is an example in which main-scanning positional deviation correction is executed based on the detected ambient temperature. The mechanical configuration of the color image forming apparatus and the electrical configuration including the control configuration are the same as those in the first embodiment, and a duplicate description is omitted. Further, the processing procedure in the third embodiment is also the same as that in the first embodiment.

  In the third embodiment, the alignment controller 203 clears the main scanning magnification correction amount Xs to 0 when executing correction at the start of printing (step S101—Yes), and the synchronization detection sensor 1 of the synchronization detection signal (XDETP) at that time. The output interval Yds of the non-parallel PD 44-3 is stored, and the temperature Ts of the temperature sensor 48 is stored (step S102).

  The system controller 201 requests the alignment controller 203 to execute inter-page correction between pages during continuous printing (No in step S101). In response to the inter-page correction execution request, the alignment controller 203 executes main scanning magnification correction and sub-scanning position correction, adds the main scanning magnification correction amount to Xs, and outputs the print start output interval Yds and the current output interval. The difference between Ydd and Ydd is stored (step S103), and the added main scanning magnification correction amount Xs is greater than or equal to a preset threshold value Xt (step S105-Yes), and the output interval difference Ydd is greater than or equal to Ydt (step (S106-Yes), the temperature Tp of the temperature sensor 18 is acquired, and when the difference between Tp and Ts is equal to or greater than a preset threshold value Tt, a positioning execution request is output to the system controller 46 ( Step S106).

  Upon receiving the alignment execution request, the system controller 201 temporarily stops printing, executes alignment, and resumes printing after completion of alignment.

  Other parts not specifically described are configured in the same manner as in the first embodiment and function in the same manner.

  According to the present embodiment, since the execution condition of the positional deviation correction is determined by combining the temperature condition with the main scanning magnification correction amount and the sub-scanning positional deviation amount of the synchronization position, it is possible to reduce the number of times of alignment execution. The productivity can be improved while maintaining the printing quality.

  In the fourth embodiment, the temperature at the start of continuous printing is compared with the temperature at the time of obtaining the inter-page count value, and the main scanning alignment correction amount, the sub-scanning alignment correction amount, the number of continuous prints, and the temperature comparison result In this example, when all exceed a preset threshold, continuous printing is interrupted and alignment is executed.

  FIG. 8 is a flowchart illustrating a processing procedure according to the fourth embodiment. In this processing procedure, the alignment controller 203 clears the main scanning magnification correction amount Xs to 0 when the printing start correction is executed (step S201-Yes), and the first synchronization detection of the synchronization detection signal (XDETP) at that time. The output interval Yds of the sensor 44-1 and the non-parallel PD 44-3 is stored, and the count value Ps of the printed sheet counter 17 and the temperature Ts of the temperature sensor 18 are stored (step S202).

  The system controller 201 requests the alignment controller 203 to execute inter-page correction between pages during continuous printing (No in step S201). In response to the inter-page correction execution request, the alignment controller 203 executes main scanning magnification correction and sub-scanning position correction, adds the main scanning magnification correction amount to Xs, and outputs the print start output interval Yds and the current output interval. The difference between Ydd and Ydd is stored (step S203), the added main scanning magnification correction amount Xs is equal to or greater than a preset threshold value Xt (step S204-Yes), and the output interval difference Ydd is equal to or greater than Ydt (step (S205-Yes), the count value Pp of the printed sheet counter 47 is acquired, and if the difference between the count values Pp and Ps is greater than or equal to a preset threshold value Pt (step S206-Yes), the temperature sensor 48 is reached. Temperature Tp is acquired, and when the difference between Tp and Ts is equal to or greater than a preset threshold value Tt (step S207—Yes), And it outputs a positioning execution request to the controller 46 (step S208).

  Upon receiving the alignment execution request, the system controller 201 temporarily stops printing, executes alignment, and resumes printing after completion of alignment.

  Other parts not specifically described are configured in the same manner as in the first embodiment and function in the same manner.

  According to the present embodiment, since the execution condition of the misalignment correction is determined by combining the main scanning magnification correction amount and the sub-scanning position misalignment amount of the synchronization position with the continuous printing number and the temperature condition, the number of times of alignment is reduced. Therefore, productivity can be improved while maintaining print quality.

  In the first to fourth embodiments, when the system controller 201 receives an alignment execution request, the system controller 201 temporarily stops printing, executes alignment, and resumes printing after the alignment is completed. However, if the execution condition is satisfied during continuous printing (when an alignment execution request is received), if printing is temporarily interrupted, the end time of the job being executed is delayed by the amount of the interruption. That is, it takes time to print the job. Therefore, in this embodiment, the fact that the alignment execution condition has been reached is stored, and the alignment is executed after the end of continuous printing.

  FIG. 9 is a flowchart illustrating a processing procedure when a positioning execution request is received according to the fifth embodiment. In the figure, when receiving an alignment execution request, the system controller 201 stores that the alignment execution request has been received (step S301). At the end of printing, the system controller 201 checks whether or not an alignment execution request has been received (step S302). If the alignment execution request has been received (step S302-Yes), the alignment is executed. (Step S303), the stored registration execution request reception information is erased (Step S304).

  Other parts not specifically described are configured in the same manner as in the first to fourth embodiments and function in the same manner.

  According to this embodiment, since alignment is not performed during continuous printing, it is possible to print out without reducing productivity during continuous printing, and alignment is performed after continuous printing. Printing quality that is not inconvenient in practice can also be maintained.

  In the fifth embodiment, when the registration execution request is received during the continuous printing, the alignment control is executed after the continuous printing is finished. However, the printing is interrupted as in the first to fourth embodiments. In some cases, it is desired to perform alignment correction control. In other words, whether the image quality is emphasized even if the work efficiency is lowered, or whether the work efficiency is emphasized even if the image quality is slightly lowered depends on the print object and the user's request.

  Therefore, in this embodiment, the execution time of the alignment correction control can be set according to the user's request. In this embodiment, when a registration execution request is received, whether printing is interrupted and alignment correction control is executed, whether printing is continued during continuous printing, and alignment correction control is executed when continuous printing ends. Selection can be made in advance from an operation panel (not shown), and alignment correction control is executed in accordance with the selection contents.

  FIG. 10 is a flowchart showing a processing procedure when this user selection is performed. In this processing procedure, the user sets whether or not alignment is executed during continuous printing from an operation panel (not shown). When receiving the alignment execution request, the system controller 201 acquires the set alignment execution condition (step S401). If the alignment execution condition is execution during continuous printing (step S402—Yes), the system controller 201 temporarily stops printing (step S403) and executes alignment (step S404), and after the alignment is completed. Printing is resumed (step S405). When the alignment execution condition is after the end of continuous printing (step S402-No), it is stored that the alignment execution request has been received (step S406).

  At the end of printing, if the system controller 201 has received an alignment execution request, the system controller 201 executes alignment and erases the stored alignment execution request reception information.

  Other parts not specifically described are configured in the same manner as in the first to fourth embodiments and function in the same manner.

  According to the present embodiment, since it is possible to select to perform alignment during continuous printing, the user can select whether to place importance on image quality or on productivity, and user operability. Can be increased.

In addition, this invention is not limited to this embodiment, All the technical matters contained in the technical idea of the invention described in the claim are objects of this invention.

DESCRIPTION OF SYMBOLS 1 Image formation part 4 Exposure apparatus (light beam scanning device)
8 Conveyor belts 14 and 15 Position shift detection sensor 16 A / D converter 17 Printed sheet counter 18 Temperature sensor 19 ROM
20 RAM
21, 22 Misalignment detection pattern 201 System controller 202 Pixel clock generation unit 203 Positioning controller

JP 2004-295083 A JP 2003-149905 A JP 2007-212873 A

Claims (7)

Image forming means for forming a multicolor image by superimposing a plurality of single color images;
Pattern forming means for forming a misregistration correction pattern between adjacent monochrome image forming sections;
A displacement detection means for optically reading the formed displacement correction pattern and detecting a displacement amount;
Correction means for correcting the positional deviation of the image based on the positional deviation amount detected by the positional deviation detection means;
An image forming apparatus having
The correction unit includes a main scanning magnification correction unit that performs main scanning magnification correction between pages being continuously printed, and a sub scanning magnification correction unit that performs sub scanning magnification correction,
When the correction result of the main scanning magnification correction means or the sub scanning magnification correction means exceeds a preset threshold value, the correction means interrupts continuous printing and uses the main scanning magnification correction means and the sub scanning magnification correction means. An image forming apparatus that executes alignment correction. The image forming apparatus according to claim 1,
It further comprises holding means for holding the correction result,
The main scanning magnification correction means is provided outside the image forming areas on the leading end side and the trailing end side of the image forming area, and detects the scanned light beam and outputs a synchronization detection signal respectively. And a first count for counting a first time from the output of the first synchronization detection signal of the first light detection means to the output of the second synchronization detection signal of the second light detection means. Means for correcting the main scanning magnification by obtaining an alignment correction amount for main scanning based on the counted first time,
The sub-scanning magnification correction means is provided non-parallel to the first light detection means on the downstream side in the light scanning direction of the first light detection means, detects a scanned light beam, and detects a synchronization detection signal. And a second counting means for counting a second time from the synchronization detection signal output of the first light detection means to the synchronization detection signal output of the third light detection means. And correcting a sub-scanning magnification by obtaining a sub-scan alignment correction amount based on the counted second time,
The image forming apparatus according to claim 1, wherein the holding unit holds an alignment correction amount for the main scanning and the sub scanning. The image forming apparatus according to claim 2,
The holding unit holds an alignment correction amount in the main scanning direction from the start of correction, and the main scanning correction amount is a correction amount from the start of alignment correction. The image forming apparatus according to any one of claims 1 to 3,
A third counting means for counting the number of continuously printed sheets;
An image forming apparatus characterized in that if the number of continuous prints exceeds a preset threshold value as a result of counting by the third counting means, continuous printing is interrupted and alignment is executed. The image forming apparatus according to any one of claims 1 to 4, wherein
Temperature detecting means for detecting the ambient temperature;
Comparison means for comparing the temperature at the start of continuous printing and the temperature at the time of obtaining the count value between pages,
Further comprising
According to a comparison result of the comparison unit, when the temperature difference exceeds a preset threshold, continuous printing is interrupted and alignment is executed. Image forming means for forming a multicolor image by superimposing a plurality of single color images;
Pattern forming means for forming a misregistration correction pattern between adjacent monochrome image forming sections;
A displacement detection means for optically reading the formed displacement correction pattern and detecting a displacement amount;
Correction means for correcting the positional deviation of the image based on the positional deviation amount detected by the positional deviation detection means;
And an alignment correction method for an image forming apparatus that performs alignment correction for main scanning and sub-scanning at a predetermined timing,
Execute main scanning magnification correction and sub scanning magnification correction between pages during continuous printing,
When the main scanning magnification correction result or the sub scanning magnification correction result exceeds a preset threshold value, continuous printing is interrupted and alignment correction by the main scanning magnification correction and the sub scanning magnification correction is executed. Alignment correction method to be performed. Image forming means for forming a multicolor image by superimposing a plurality of single color images;
Pattern forming means for forming a misregistration correction pattern between adjacent monochrome image forming sections;
A displacement detection means for optically reading the formed displacement correction pattern and detecting a displacement amount;
Correction means for correcting the positional deviation of the image based on the positional deviation amount detected by the positional deviation detection means;
An alignment correction control program for an image forming apparatus for executing alignment correction control for main scanning and sub-scanning at a predetermined timing by a computer,
A procedure for performing main scanning magnification correction and sub-scanning magnification correction between pages during continuous printing;
When the main scanning magnification correction result or the sub scanning magnification correction result exceeds a preset threshold value, a procedure for interrupting continuous printing and performing alignment correction by the main scanning magnification correction and the sub scanning magnification correction;
An alignment correction control program comprising:

Images