JP2005202284A - Color image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color image forming apparatus carrying out appropriate compensation for color smearing by corresponding to shortening of printing time and higher quality of the printed quality. <P>SOLUTION: The color image forming apparatus 1 forms a compensation pattern to compensate misregistration of each color in a color image formation on a transfer belt 4 by each image forming process parts 5Bk, 5M, 5C and 5Y. The compensation pattern is detected by detection sensors 8a to 8c and based on the detection result, compensation values for the compensation subject driven matters, including the image process parts 5Bk to 5Y are calculated at a control part 9. When the compensation subject driven matters are driven and controlled based on the compensation value and compensated, one of the compensation patterns in compensation levels of two stages are formed, which are horizontal scanning fine compensation pattern and vertical scanning fine compensation pattern or the horizontal rough compensation pattern and the vertical rough compensation pattern. A compensation value is calculated according to the formed compensation patterns. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a color image forming apparatus, and more particularly, to a color image forming apparatus that appropriately performs color misregistration correction that appropriately responds to demands for shortening printing time and improving print quality.

  Conventionally, as a so-called tandem-type color image forming apparatus that forms a full-color image by arranging a plurality of electrophotographic writing units and image forming units in parallel, for example, a full-color copying machine or the like is used. is there. Such a full-color copying machine includes an image forming station that forms an image of each color of cyan, magenta, yellow, and black. The image forming station of each color includes a writing unit and an image forming unit, and image data of each color. The latent image is formed by irradiating the laser modulated by the writing unit to the photoconductor of the image forming unit, and each color image forming unit supplies toner of each color to the photoconductor on which the latent image is formed. The toner image of each color is developed. Each color image forming unit sequentially transfers the toner image on the photoconductor onto the transfer paper or transfer belt conveyed on the conveyance belt, and finally forms a color image obtained by superimposing the toner images of the respective colors on the transfer paper. Form.

  As described above, in a color image forming apparatus having a plurality of image forming stations, each image forming station is compared with a color image forming apparatus in which only one photoconductor called a one-drum system is provided to form a color image. Since color images are formed by sequentially superimposing toner images of different colors on the same surface of the same transfer paper or transfer belt, if the transfer image position to the transfer paper or transfer belt in each image forming station is shifted, The interval between images formed at each image forming station is shifted or overlapped. In the case of a color image, the color quality is different or the color shift is deteriorated.

  This misalignment includes the inclination of the scanning line for each color due to an assembly error inside the writing optical system, an attachment error of each unit to the color image forming apparatus main body, and an attachment error of the photosensitive member to the color image forming apparatus main body. There is a positional deviation of the tilt that occurs, and a parallel positional deviation that occurs when the position of the scanning line is shifted in parallel to the reference position and the four color images are shifted in the vertical or horizontal direction as a whole. Among these misalignments, the misalignment is corrected by finely adjusting the position of the reflection mirror of the writing unit, and the parallel misalignment is adjusted for the write start timing in the main scanning direction or the sub scanning direction. By doing so, correction can be performed. In addition, the length of the image in the main scanning direction can be adjusted by changing the frequency of the writing pixel, that is, by adjusting the magnification error.

  And even if the color image forming apparatus is initially adjusted, such misregistration is not only caused by replacement of the image forming unit, maintenance of the color image forming apparatus, transportation of the color image forming apparatus, etc. Also due to the temperature expansion of the mechanism after the formation of a plurality of images, the error fluctuates over time.

  On the other hand, a user of a color image forming apparatus may have different requests for a formed image depending on the occasion when forming a color image. For example, a high-quality image with high accuracy may be requested while accepting that it takes some time, or a printout in a shorter time may be requested without requiring so much accuracy.

  Therefore, the present applicant first drives and controls the correction target driving object including the image processing unit, forms a correction pattern for correcting misregistration of each color on the transfer belt, and detects the presence or absence of the correction pattern. Based on the recognition value of the correction pattern formation position based on the output value of the detection sensor, and based on the recognition result of the correction pattern formation position, correction to be performed during the drive control of the correction target drive object When a color image is formed on a transfer medium by calculating a value, a correction pattern is formed and recognized, a correction value is calculated, and a color registration process for driving and controlling a correction target driven object is different based on the correction value. A color image forming apparatus has been proposed in which an execution mode for executing a plurality of processes is provided and each of the execution modes can be selected (see Patent Document 1).

JP 2002-244387 A

  However, in the color image forming apparatus described in the above publication, a plurality of different alignment processes for each color for driving and controlling the correction target driven object based on the correction value calculated based on the recognition result of the formed correction pattern. Since multiple execution modes for executing processing were selected, it was possible to correct misalignment more easily and with higher accuracy, and at the same time, shortened the printing time of the user and improved print quality. There was a need for improvement in order to respond appropriately according to the demands of the development.

  Accordingly, the invention according to claim 1 forms an electrostatic latent image by irradiating a rotationally driven photoconductor with writing light modulated by image data, and the photoconductor on which the electrostatic latent image is formed. A toner of a predetermined color is supplied and developed, and a toner image formed on the photoconductor is transferred onto a transfer belt or transferred onto a transfer paper conveyed on the transfer belt, A plurality of image process units that form toner images are arranged along the transfer belt, and each image process unit sequentially transfers toner images of different colors onto the transfer belt or transfer paper to form a color image. In addition, a correction pattern for correcting the color misregistration at the time of color image formation by a plurality of image processing units is formed on the transfer belt by each image processing unit, and the correction pattern is detected by the detection unit, Detection hand When the correction value calculation means calculates the correction value of the correction target driving object including the image process unit based on the detection result of the correction, and corrects the correction target driving object by driving the correction target based on the correction value. As a correction pattern, one of two correction level correction patterns, a fine adjustment pattern for finely adjusting color misregistration and a coarse adjustment pattern larger than the fine adjustment pattern and having a wide pattern interval, is formed. By calculating and correcting the correction value according to the formed fine adjustment pattern or coarse adjustment pattern, stepwise correction is performed according to the amount of color misregistration, and the print time is shortened while image quality is reduced. An object of the present invention is to provide a color image processing apparatus that improves the image quality.

  The invention according to claim 2 provides a plurality of stepwise correction levels, sets the correction level based on the detection result of the correction pattern by the detecting means, selects a correction pattern to be formed according to the correction level, and By calculating correction values and performing stepwise color misregistration correction, stepwise correction corresponding to the amount of color misregistration is performed more appropriately, and the print time is further shortened and image quality is improved. An object is to provide a color image processing apparatus.

  According to the third aspect of the present invention, three correction levels of a low accuracy level, a medium accuracy level, and a high accuracy level are provided as a plurality of correction levels, and the correction processing of the three correction levels is performed according to the degree of color misregistration. Is intended to provide a color image processing apparatus that performs stepwise correction more appropriately according to the amount of color misregistration and further improves the image quality while further shortening the printing time.

  According to a fourth aspect of the present invention, when the fine adjustment pattern is formed as the correction pattern and the detection result obtained by detecting the fine adjustment pattern by the detecting means is at a low accuracy level, the coarse adjustment pattern is formed as the correction pattern. The coarse tone correction pattern is detected by the detection unit, and correction processing having a large correction width is performed based on the correction value calculated by the correction value calculation unit based on the detection result, so that when the color misregistration is large, the coarse correction is performed. An object of the present invention is to provide a color image processing apparatus that can quickly reduce the amount of misalignment and further improve the image quality while further shortening the printing time.

  According to the fifth aspect of the present invention, when the detection result obtained by forming the fine adjustment pattern as the correction pattern and detecting the fine adjustment pattern by the detection means is a medium accuracy level, the correction value calculation means calculates based on the detection result. The correction process is performed based on the corrected value, and the fine adjustment pattern is formed again as the correction pattern, and the correction process is performed, so that stepwise correction corresponding to the amount of color misregistration is performed more appropriately, and the printing time is further reduced. It is an object of the present invention to provide a color image processing apparatus that improves image quality while improving the image quality.

  According to the sixth aspect of the present invention, when the detection result obtained by forming the fine adjustment pattern as the correction pattern and detecting the fine adjustment pattern by the detection unit is a high accuracy level, the correction value calculation unit calculates based on the detection result. If the color misregistration amount is reduced by performing the correction processing based on the corrected value and finishing the correction processing, the small color misregistration amount is corrected and the processing is terminated, and the printing time is further shortened. An object of the present invention is to provide a color image processing apparatus that improves image quality.

  According to the seventh aspect of the present invention, a low-precision level, a medium-precision level, and a high-precision level are formed until a detection result obtained by forming a fine-correction pattern as a correction pattern and detecting the fine-correction correction pattern by the detection unit reaches a high-precision level. It is an object of the present invention to provide a color image processing apparatus that improves the image quality while reducing the amount of color misregistration step by step by repeating the correction processing of the three levels of correction levels to shorten the print time. Yes.

  According to the eighth aspect of the present invention, a low-precision level, a medium-precision level, and a high-precision level are formed until a detection result obtained by forming a fine-correction correction pattern as a correction pattern and detecting the fine-correction correction pattern by the detection means reaches a high-accuracy level. By repeatedly performing the correction process of the three stages of correction levels within a specified number of times, the amount of color misregistration is corrected stepwise within the time according to the usage situation of the user, and the usability is improved. An object of the present invention is to provide a color image processing apparatus that improves image quality.

  The color image processing apparatus according to the first aspect of the invention forms an electrostatic latent image by irradiating a rotationally driven photoconductor with writing light modulated by image data, and the electrostatic latent image is formed. The toner of a predetermined color is supplied to the photosensitive member and developed, and the toner image formed on the photosensitive member is transferred onto the transfer belt or transferred onto the transfer paper conveyed on the transfer belt. A plurality of image processing units for forming toner images are provided along the transfer belt, and toner images of different colors are sequentially superimposed on the transfer belt or the transfer paper in each of the image processing units. A color image is formed by transfer, and a correction pattern for correcting a positional shift of each color at the time of forming the color image by the plurality of image processing units is formed on the transfer belt in each image processing unit, This A correction value is detected by a detection means, and a correction value calculation means for calculating a correction value of a correction target driving object including the image process unit based on the detection result of the detection means; and on the transfer belt or the transfer paper A correction unit that drives and controls the correction target driven object based on the correction value when forming a color image, wherein the color image forming apparatus performs fine adjustment to finely adjust the color shift as the correction pattern. One of the two correction levels of the correction pattern and the coarse adjustment pattern that is larger than the fine adjustment pattern and has a wide pattern interval is formed, and the fine adjustment pattern or coarse adjustment thus formed is formed. The above object is achieved by calculating and correcting the correction value according to the pattern.

  In this case, for example, as described in claim 2, the color image forming apparatus includes a plurality of stepwise correction levels, and sets the correction level based on the detection result of the correction pattern by the detection unit. The correction of the color shift stepwise may be performed by selecting the correction pattern to be formed and calculating the correction value according to the correction level.

  For example, as described in claim 3, the color image forming apparatus includes three correction levels, a low accuracy level, a medium accuracy level, and a high accuracy level, as the plurality of correction levels. Depending on the degree, the three levels of correction level correction processing may be executed.

  Furthermore, for example, as described in claim 4, the color image forming apparatus forms the fine adjustment pattern as the correction pattern, and the detection result obtained by detecting the fine adjustment pattern with the detection unit is the low accuracy level. The coarse adjustment pattern is formed as the correction pattern, the coarse adjustment pattern is detected by the detection unit, and based on the correction value calculated by the correction value calculation unit based on the detection result A correction process having a large correction width may be performed.

  For example, as described in claim 5, the color image forming apparatus forms the fine adjustment pattern as the correction pattern, and a detection result obtained by detecting the fine adjustment pattern with the detection unit is the medium accuracy level. If it is, the correction processing is performed based on the correction value calculated by the correction value calculation means based on the detection result, and the correction processing is performed again by forming the fine adjustment pattern as the correction pattern. Good.

  Further, for example, the color image forming apparatus forms the fine adjustment pattern as the correction pattern, and a detection result obtained by detecting the fine adjustment pattern with the detection unit is the high accuracy level. If so, the correction processing may be performed based on the correction value calculated by the correction value calculation means based on the detection result, and the correction processing may be terminated.

  For example, as described in claim 7, the color image forming apparatus forms the fine adjustment pattern as the correction pattern, and a detection result obtained by detecting the fine adjustment pattern with the detection unit is the high accuracy level. Until this time, the correction processing of the three correction levels of the low accuracy level, the medium accuracy level, and the high accuracy level may be repeatedly performed.

  Furthermore, for example, as described in claim 8, the color image forming apparatus forms the fine adjustment pattern as the correction pattern, and a detection result obtained by detecting the fine adjustment pattern with the detection unit is the high accuracy level. Until this time, the correction processing of the three correction levels of the low accuracy level, the medium accuracy level, and the high accuracy level may be repeated within a specified number of times.

  According to the color image processing apparatus of the first aspect, the electrostatic latent image is formed by irradiating the rotationally driven photoconductor with the writing light modulated by the image data. Transfer paper on which the toner of a predetermined color is supplied and developed on the formed photoconductor, and the toner image formed on the photoconductor is transferred onto the transfer belt or conveyed on the transfer belt A plurality of image process units are formed along the transfer belt to transfer toner images of different colors, and each image process unit sequentially transfers toner images of different colors onto the transfer belt or transfer paper. In addition to forming a color image, a correction pattern for correcting misregistration of each color at the time of color image formation by a plurality of image processing units is formed on the transfer belt in each image processing unit, and the correction pattern is detected so Based on the detection result of the detection means, the correction value calculation means calculates the correction value of the correction target drive object including the image process unit, and the correction means drives the correction target drive object based on the correction value. When the correction is performed, the correction pattern is either a fine adjustment pattern for finely adjusting color misregistration and a correction pattern having two correction levels, a coarse adjustment pattern larger than the fine adjustment pattern and having a wide pattern interval. Since a correction pattern is formed and a correction value is calculated and corrected according to the formed fine adjustment pattern or coarse adjustment pattern, correction can be performed step by step according to the amount of color misregistration, and printing time can be reduced. It can be shortened and the image quality can be improved.

  According to the color image processing apparatus of the second aspect of the present invention, a plurality of stepwise correction levels are provided, the correction level is set based on the detection result of the correction pattern by the detection means, and the correction level is set according to the correction level. By selecting the correction pattern to be formed and calculating the correction value, the color misregistration is corrected step by step, so that it is possible to perform more appropriate stepwise correction according to the amount of color misregistration, further reducing the printing time. Image quality can be improved.

  According to the color image processing apparatus of the third aspect of the present invention, the three correction levels of the low accuracy level, the medium accuracy level, and the high accuracy level are provided as the plurality of correction levels, and the three correction levels are set according to the degree of color misregistration. Since the correction processing of the step correction level is executed, step-by-step correction corresponding to the amount of color misregistration can be performed more appropriately, the print time can be further shortened, and the image quality can be improved. it can.

  According to the color image processing apparatus of the fourth aspect of the invention, if the detection result obtained by forming the fine adjustment pattern as the correction pattern and detecting the fine adjustment pattern by the detecting means is at a low accuracy level, Since the tone correction pattern is formed, the coarse correction pattern is detected by the detection unit, and the correction process having a large correction width is performed based on the correction value calculated by the correction value calculation unit based on the detection result. When it is large, it can be corrected roughly and the amount of misalignment can be quickly reduced, the printing time can be further shortened, and the image quality can be improved.

  According to the color image processing apparatus of the fifth aspect of the present invention, if the detection result obtained by forming the fine adjustment pattern as the correction pattern and detecting the fine adjustment pattern by the detecting means is the medium accuracy level, the detection result is based on the detection result. The correction processing is performed based on the correction value calculated by the correction value calculation means, and the fine adjustment pattern is formed again as the correction pattern to perform the correction processing. Therefore, stepwise correction corresponding to the amount of color misregistration is performed more appropriately. As a result, the printing time can be further shortened and the image quality can be improved.

  According to the color image processing apparatus of the sixth aspect of the present invention, if the detection result obtained by forming the fine adjustment pattern as the correction pattern and detecting the fine adjustment pattern by the detecting means is a high accuracy level, the detection result is based on the detection result. Correction processing is performed based on the correction value calculated by the correction value calculation means, and the correction processing is completed.If the color misregistration amount is small, the small color misregistration amount can be corrected and the processing can be terminated. The print time can be further shortened and the image quality can be improved.

  According to the color image processing apparatus of the seventh aspect of the present invention, a low accuracy level, a medium level are obtained until a detection result obtained by forming a fine adjustment pattern as a correction pattern and detecting the fine adjustment pattern by the detecting means becomes a high accuracy level. Since the correction process of the three correction levels of the accuracy level and the high accuracy level is repeatedly performed, the amount of color misregistration can be corrected stepwise, the print time can be shortened, and the image quality can be improved. Can be made.

  According to the color image processing apparatus of the eighth aspect of the present invention, a low accuracy level, a medium accuracy level, until a detection result obtained by forming a fine adjustment pattern as a correction pattern and detecting the fine adjustment pattern by the detecting means reaches a high accuracy level. Since the correction processing of the three correction levels of the accuracy level and the high accuracy level is repeatedly performed within a specified number of times, the color misregistration amount can be corrected in a stepwise manner within a time corresponding to the use situation of the user. In addition, the usability can be improved and the image quality can be improved.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, since the Example described below is a suitable Example of this invention, various technically preferable restrictions are attached | subjected, However, The scope of the present invention limits this invention especially in the following description. As long as there is no description of the effect, it is not restricted to these aspects.

  1 to 6 are diagrams showing an embodiment of a color image forming apparatus according to the present invention, and FIG. 1 is a main portion of the color image forming apparatus 1 to which an embodiment of the color image forming apparatus according to the present invention is applied. It is a front schematic block diagram.

  In FIG. 1, in the color image forming apparatus 1, an endless belt-like transfer belt 4 is stretched between two drive rollers 2a and 2b and a driven roller 3 arranged at substantially parallel positions. The drive rollers 2a, 2b are rotated counterclockwise by being driven to rotate by a drive motor (not shown).

  The color image processing apparatus 1 includes an image processing unit 5Bk for each color of black (Bk), magenta (M), cyan (C), and yellow (Y) along the transfer belt 4 between the driving roller 2a and the driving roller 2b. 5M, 5C, and 5Y are arranged side by side, and the writing unit 6 is disposed above the image processing units 5Bk, 5M, 5C, and 5Y.

  In the color image processing apparatus 1, a waste toner portion 7 for removing toner on the transfer belt 4 is disposed between the driven roller 3 and the driving roller 2 a, and between the driving roller 2 b and the driven roller 3. In the meantime, as shown in FIG. 2, three color misregistration detection sensors (detecting means) 8a, 8b, and 8c arranged side by side in the sub-scanning direction of the transfer belt 4 are arranged. Each color misregistration detection sensor 8 a, 8 b, 8 c outputs the detection signal to the control unit 9.

  Each of the image processing units 5Bk, 5M, 5C, and 5Y includes a photosensitive drum 10Bk, 10M, 10C, and 10Y, a sub hopper 11Bk, 11M, 11C, and 11Y, a developing bias roller 12Bk, 12M, 12C, and 12Y, and the like. The bias rollers 12Bk, 12M, 12C, and 12Y are disposed at positions facing the corresponding photosensitive drums 10Bk, 10M, 10C, and 10Y with the transfer belt 4 interposed therebetween.

  Each of the image processing units 5Bk, 5M, 5C, and 5Y irradiates each photosensitive drum 10Bk, 10M, 10C, and 10Y with a laser beam for each color that is modulated by the image data of each color from the writing unit 6. An electrostatic latent image for each color is formed on the surface of each of the photosensitive drums 10Bk, 10M, 10C, and 10Y, and the respective photosensitive drums 10Bk, 10M, and 10D are transferred from the sub hoppers 11Bk, 11M, 11C, and 11Y that store the toners of the respective colors. By supplying toner to 10C and 10Y, the electrostatic latent images on the photoconductive drums 10Bk, 10M, 10C, and 10Y are developed to form toner images of the respective colors. The image processing units 5Bk, 5M, 5C, and 5Y transfer the toner images on the photosensitive drums 10Bk, 10M, 10C, and 10Y onto the transfer belt 4 directly or on the transfer belt 4, respectively. In addition, a color image is formed by sequentially superimposing and transferring with the developing bias rollers 12Bk, 12M, 12C, and 12Y, and the waste toner portion 7 removes the toner remaining on the transfer belt 4. The color image processing apparatus 1 forms a color image by fixing a transfer sheet on which a color image is transferred and fixed by a fixing unit (not shown).

  As shown in FIG. 2, the color image processing apparatus 1 corrects the color misregistration during the color image formation by using the image processing units 5Bk, 5M, 5C, and 5Y on the transfer belt 4 as a correction pattern. Three main scanning color misregistration detection patterns 20 and three sub scanning color misregistration detection patterns 21 are formed side by side in the main scanning direction. In the main scanning color misregistration detection pattern 20, detection patterns 20M, 20C, 20Y are sequentially arranged, and in the sub-scanning color misregistration detection pattern 21, the cyan pattern is used as the reference sub-scanning color misregistration detection pattern 21G, and the yellow (Y), magenta (M), and cyan (C) sub-scans are sequentially performed. The color misregistration detection patterns 21Y, 21M, and 21C are sequentially arranged in the sub-scanning direction.

  The main scanning color misregistration detection pattern 20 is a black (Bk) reference patch line (Bk) extending at a predetermined angle in the sub-scanning direction as shown in FIG. 3 with respect to the magenta (M) main scanning color misregistration detection pattern 20M. Bk line) and a magenta line (M line) extending in the sub-scanning direction are formed by lines intersecting at a predetermined angle.

  Further, as shown in FIG. 4, the sub-scanning color misregistration detection pattern 21 uses a rectangular cyan (C) patch having a predetermined width in the sub-scanning direction and a predetermined length in the main scanning direction as a reference patch 21G. A black rectangular patch and yellow (Y), magenta (M), and cyan (C) patches are adjacent to each other in a sub-scanning color shift yellow detection pattern 21Y, a sub-scanning color shift magenta detection pattern 21M, and a sub-scanning color shift cyan detection. The patterns 21C are arranged at predetermined intervals in the sub-scanning direction, and three rows are formed at predetermined intervals in the main scanning direction.

  The color misregistration detection sensors 8a, 8b, and 8c detect the main scanning color misregistration detection pattern 20 and the sub-scanning color misregistration detection pattern 21 formed on the transfer belt 4 and send the detection signals to the control unit 9. However, the detection signal is not output for the black (Bk) color, and the detection signal is output for the other colors. Therefore, by shifting the position of each color pattern of the main scanning color misregistration detection pattern 20 and the sub-scanning color misregistration detection pattern 21, the overlapping area with the black (Bk) color is changed, and the arrangement position of each pattern is changed. It is possible to detect a shift in image formation.

  The control unit (correction value calculation unit, correction unit) 9 controls each unit of the color image forming apparatus 1 to execute the process as the color image forming apparatus 1 and the color misregistration detection sensors 8a, 8b, and 8c. Based on the detection result, driven parts such as the image processing parts 5Bk, 5M, 5C, and 5Y are driven to correct color misregistration. Specifically, the control unit 9 compares the detection results of the color misregistration detection sensors 8a, 8b, and 8c with theoretical values estimated from the arrangement positions of the main scanning color misregistration detection pattern 20 and the sub-scanning color misregistration detection pattern 21. In order to correct the color misregistration amount, the misregistration amount of the detection result of the color misregistration detection sensors 8a, 8b, and 8c from the theoretical value is used as a color misregistration amount. A correction process for calculating the correction amount of the drive system and feeding back the correction amount to the correction target drive system is performed. Then, the control unit 9 controls the image processing units 5Bk, 5M, 5C, and 5Y, and the types of the main-scanning color misregistration detection pattern 20 and the sub-scanning color misregistration detection pattern 21 corresponding to the color misregistration amount and the pattern 20 21, the color misregistration is corrected step by step, and the amount of color misregistration is also detected when correction is not possible due to the failure of correction when the color misregistration occurs and the state of the color image forming apparatus 1. The color misregistration can be reduced by performing correction processing in a range corresponding to.

  Next, the operation of this embodiment will be described. The color image forming apparatus 1 uses the image processing units 5Bk, 5M, 5C, and 5Y to detect the types of the main-scanning color misregistration detection pattern 20 and the sub-scanning color misregistration detection pattern 21 on the transfer belt 4 and the detection processing of the patterns 20 and 21. To correct the color shift step by step.

  Prior to image formation, the color image forming apparatus 1 first executes color misregistration correction processing under the control of the control unit 9. That is, as shown in FIG. 5, the control unit 9 executes a fine adjustment correction process. In the fine adjustment correction process, first, the drive roller 2a and the drive roller 2b are rotated and the transfer belt 4 is rotated. The writing unit 6 and the image processing units 5Bk, 5M, 5C, and 5Y are driven to form a main scanning correction fine adjustment pattern as the main scanning color misregistration detection pattern 20 (step S101), and the formed main scanning correction is performed. The fine adjustment pattern is detected by the color misregistration detection sensors 8a, 8b, and 8c (step S102). The main scanning correction fine adjustment pattern is the main scanning color misregistration detection pattern 20 shown in FIGS. 2 and 3, and as described above, yellow (Y) and cyan (C) with reference to the black (Bk) color. , Magenta (M) color patterns are formed.

  Next, the control unit 9 forms a sub-scanning correction fine adjustment pattern as the sub-scanning color misregistration detection pattern 21 (step S103), and uses the formed sub-scanning correction fine adjustment pattern as the color misregistration detection sensors 8a, 8b, and 8c. (Step S104). This sub-scanning correction fine adjustment pattern is the sub-scanning color misregistration detection pattern 21 shown in FIGS. 2 and 4, and as described above, yellow (Y), cyan (C) with reference to the black (Bk) color. , Magenta (M) color patterns are formed.

  When the control unit 9 causes the color misregistration detection sensors 8a, 8b, and 8c to detect the main scanning correction fine adjustment pattern and the sub-scanning correction fine adjustment pattern, the control unit 9 detects the main scanning correction fine adjustment pattern. The detection result of the fine adjustment pattern and the fine adjustment pattern for sub-scanning correction is compared with the theoretical value calculated from the arrangement position of the fine adjustment pattern for main scanning correction and the fine adjustment pattern for sub-scan correction, and the amount of deviation is compared with the amount of color deviation. Color misregistration amount calculation processing is performed (step S105). In this case, the theoretical minimum output position is used as the theoretical value calculated from the arrangement position of the fine adjustment pattern for main scanning correction and the fine adjustment pattern for sub scanning correction.

  When calculating the color misregistration amount, the control unit 9 calculates the correction amount by converting the color misregistration amount into a set value for each correction target drive system (step S106), and whether the accuracy is high or medium accuracy. Or low accuracy is determined (step S107). The controller 9 determines this accuracy according to how much the minimum output position deviates from the theoretical value.

  In step S107, if the accuracy is medium accuracy or high accuracy, the control unit 9 performs correction by setting the obtained correction amount in each correction target drive system (step S108), and the accuracy is medium accuracy again. Or high accuracy is checked (step S109). Note that the control unit 9 determines the accuracy in this case according to how much the minimum output position deviates from the theoretical value, as in the case of step S107.

  If the accuracy is high in step S109, the control unit 9 determines that the correction has been completed and ends the process. If the accuracy is medium accuracy in step S109, the control unit 9 returns to step S101, and The same processing is performed (steps S101 to S109).

  If the accuracy determined in step S107 is low, the control unit 9 executes the coarse adjustment correction process shown in FIG.

  In the coarse adjustment correction process, as shown in FIG. 6, the controller 9 first rotates the transfer belt 4 by rotating the drive roller 2a and the drive roller 2b as in the case of the fine adjustment correction process. The writing unit 6 and the image processing units 5Bk, 5M, 5C, and 5Y are driven to form a main scanning correction coarse adjustment pattern as the main scanning color misregistration detection pattern 20 (step S201). The coarse adjustment pattern for correction is detected by the color misregistration detection sensors 8a, 8b, and 8c (step S202). The coarse adjustment pattern for main scanning correction is the same as the main scanning color misregistration detection pattern 20 shown in FIGS. 2 and 3, but the pattern size and pattern interval are widened.

  Next, the control unit 9 forms a sub-scanning correction coarse adjustment pattern as the sub-scanning color misregistration detection pattern 21 (step S203), and uses the formed sub-scanning correction coarse adjustment pattern as the color misregistration detection sensors 8a and 8b. 8c (step S204). This coarse pattern for sub-scanning correction is the same as the sub-scanning color misregistration detection pattern 20 shown in FIGS. 2 and 4, but the pattern size and pattern interval are widened.

  When the control unit 9 causes the color misregistration detection sensors 8a, 8b, and 8c to detect the main scanning correction fine adjustment pattern and the sub-scanning correction fine adjustment pattern, the control unit 9 detects the main scanning correction fine adjustment pattern. The detection result of the coarse adjustment pattern and the coarse adjustment pattern for sub-scanning correction is compared with the theoretical value calculated from the arrangement position of the coarse adjustment pattern for main scanning correction and the coarse adjustment pattern for sub-scan correction, and the deviation amount is calculated. Color misregistration amount calculation processing is performed (step S205). In this case, a theoretical minimum output position is used as a theoretical value calculated from the arrangement positions of the main scanning correction coarse adjustment pattern and the sub-scan correction coarse adjustment pattern.

  When calculating the color misregistration amount, the control unit 9 converts the color misregistration amount into a set value for each correction target drive system to calculate the correction amount (step S206), and the calculated correction amount is used as the main and sub correction amounts. The correction is performed by setting each correction target drive system, and the process returns to the fine adjustment correction process (step S207).

  As described above, the color image forming apparatus 1 according to the present exemplary embodiment includes the main scanning color misregistration detection pattern 20 for correcting the misregistration of each color during color image formation by the plurality of image processing units 5Bk, 5M, 5C, and 5Y. A sub-scanning color misregistration detection pattern 21 is formed on the transfer belt 4 by the image processing units 5Bk, 5M, 5C, and 5Y, and the main-scanning color misregistration detection pattern 20 and the sub-scanning color misregistration detection pattern 21 are color misregistration detection sensors. Based on the detection results of the color misregistration detection sensors 8a, 8b, and 8c detected by 8a, 8b, and 8c, the correction value of the correction target driving object including the image processing units 5Bk, 5M, 5C, and 5Y is detected by the control unit 9. When calculating and correcting the driving object to be corrected based on the correction value, the color misregistration is determined as the main scanning color misregistration detection pattern 20 and the sub-scanning color misregistration detection pattern 21. The main scanning correction fine adjustment pattern and the sub scanning correction fine adjustment pattern, and the main scanning correction coarse adjustment pattern and the sub scanning correction larger than the main scanning correction fine adjustment pattern and the sub scanning correction fine adjustment pattern. Either one of the correction patterns of the two correction levels of the coarse adjustment pattern is formed, and the formed main scan correction fine adjustment pattern and sub-scan correction fine adjustment pattern or main scan correction coarse adjustment pattern and sub-scan are formed. Correction coarse adjustment pattern A correction value is calculated and corrected according to the coarse adjustment pattern.

  Accordingly, stepwise correction according to the color misregistration amount can be performed, the printing time can be shortened, and the image quality can be improved.

  Further, the color image processing apparatus 1 according to the present embodiment provides a plurality of stepwise correction levels, sets the correction level based on the detection results of the correction patterns by the color misregistration detection sensors 8a, 8b, and 8c, and By selecting a correction pattern to be formed and calculating a correction value according to the correction level, the color misregistration is corrected stepwise.

  Therefore, stepwise correction corresponding to the amount of color misregistration can be performed more appropriately, the print time can be further shortened, and the image quality can be improved.

  Further, the color image processing apparatus 1 according to the present embodiment provides three correction levels of a low accuracy level, a medium accuracy level, and a high accuracy level as a plurality of correction levels, and the three steps according to the degree of color misregistration. Correction level correction processing is executed.

  Therefore, stepwise correction corresponding to the amount of color misregistration can be performed more appropriately, the print time can be further shortened, and the image quality can be improved.

  The color image processing apparatus 1 according to the present embodiment forms a fine adjustment pattern as a correction pattern, and the detection result obtained by detecting the fine adjustment pattern with the color misregistration detection sensors 8a, 8b, and 8c is at a low accuracy level. As the correction pattern, a main scanning correction fine adjustment pattern and a sub-scanning correction fine adjustment pattern are formed, and the main scanning correction fine adjustment pattern and the sub-scanning correction fine adjustment pattern are detected by the detection means, and color misregistration is performed based on the detection result. Correction processing with a large correction width is performed based on the correction values calculated by the detection sensors 8a, 8b, and 8c.

  Therefore, when the color misregistration is large, it can be corrected roughly and the amount of misregistration can be quickly reduced, the printing time can be further shortened, and the image quality can be improved.

  Further, the color image processing apparatus 1 according to the present embodiment forms a main scanning correction fine adjustment pattern and a sub-scanning correction fine adjustment pattern as correction patterns, and the main scanning correction fine adjustment pattern and the sub-scan correction fine adjustment pattern are color-shifted. If the detection results detected by the detection sensors 8a, 8b, and 8c are at the medium accuracy level, the correction processing is performed based on the correction value calculated by the control unit 9 based on the detection result, and the correction pattern is again used as a correction pattern. Correction processing is performed by forming a fine adjustment pattern and a sub-scanning correction fine adjustment pattern.

  Therefore, stepwise correction corresponding to the amount of color misregistration can be performed more appropriately, the print time can be further shortened, and the image quality can be improved.

  In addition, the color image processing apparatus 1 according to the present embodiment forms a main scanning correction fine adjustment pattern and a sub-scanning correction fine adjustment pattern as correction patterns, and the main scanning correction fine adjustment pattern and the sub-scan correction fine adjustment pattern are color-shifted. When the detection results detected by the detection sensors 8a, 8b, and 8c are at a high accuracy level, the correction process is performed based on the correction value calculated by the control unit 9 based on the detection result, and the correction process is terminated. .

  Therefore, when the color misregistration amount is small, the process can be completed by correcting the small color misregistration amount, the print time can be further shortened, and the image quality can be improved.

  Further, the color image processing apparatus 1 according to the present embodiment forms a main scanning correction fine adjustment pattern and a sub-scanning correction fine adjustment pattern as correction patterns, and the main scanning correction fine adjustment pattern and the sub-scan correction fine adjustment pattern are color-shifted. Until the detection results detected by the detection sensors 8a, 8b, and 8c reach the high accuracy level, the correction processing of the three correction levels of the low accuracy level, the medium accuracy level, and the high accuracy level is repeatedly performed.

  Accordingly, the color misregistration amount can be corrected in a stepwise manner, the printing time can be shortened, and the image quality can be improved.

  In the color image processing apparatus 1 of the present embodiment, the main scanning correction fine adjustment pattern and the sub scanning correction fine adjustment pattern are formed as the correction patterns, and the main scanning correction fine adjustment pattern and the sub scanning correction fine adjustment pattern are color-shifted. Until the detection results detected by the detection sensors 8a, 8b, and 8c reach a high accuracy level, the correction processing of the three correction levels of the low accuracy level, the medium accuracy level, and the high accuracy level is repeated within a specified number of times. You may make it perform.

  In this way, the amount of color misregistration can be corrected stepwise within the time according to the user's usage status, and the usability can be improved and the image quality can be improved.

  The invention made by the present inventor has been specifically described based on the preferred embodiments. However, the present invention is not limited to the above, and various modifications can be made without departing from the scope of the invention. Needless to say.

  The stepwise correction can be applied to a color image forming apparatus such as a color composite apparatus, a color copying apparatus, a color facsimile apparatus, and a color printer that appropriately perform color misregistration correction according to a printing time and image quality desired by the user. .

1 is a schematic front view of a main part of a color image forming apparatus to which an embodiment of a color image forming apparatus of the present invention is applied. FIG. 2 is a plan view of a main part of the transfer belt in FIG. 1 in which a main scanning color misregistration detection pattern and a sub scanning color misregistration detection pattern are formed. FIG. 3 is an enlarged explanatory diagram of a magenta main scanning color misregistration detection pattern of FIG. 2. FIG. 3 is an enlarged explanatory diagram of a sub-scanning color misregistration detection pattern in FIG. 2. 3 is a flowchart showing fine adjustment correction processing by the color image forming apparatus of FIG. 1. FIG. 6 is a flowchart showing a coarse adjustment process following the fine adjustment process of FIG. 5. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Color image forming apparatus 2a, 2b Drive roller 3 Driven roller 4 Transfer belt 5Bk, 5M, 5C, 5Y Image process part 6 Writing part 7 Waste toner part 8a, 8b, 8c Color shift detection sensor 9 Control part 10Bk, 10M, 10C, 10Y Photosensitive drums 11Bk, 11M, 11C, 11Y Sub hoppers 12Bk, 12M, 12C, 12Y Development bias roller 20 Main scanning color misregistration detection pattern 20M, 20C, 20Y Detection pattern 21 Sub scanning color misregistration detection pattern 21G Reference sub scanning color Deviation detection pattern 21Y, 21M, 21C Sub-scanning color deviation detection pattern

Claims (8)

  An electrostatic latent image is formed by irradiating a rotationally driven photoconductor with writing light modulated by image data, and toner of a predetermined color is supplied onto the photoconductor on which the electrostatic latent image is formed. An image processing unit that develops and transfers a toner image formed on the photoconductor onto a transfer belt or transfers it onto a transfer sheet conveyed on the transfer belt to form a toner image. A plurality of toner images are arranged along the transfer belt, and each of the image processing units forms a color image by sequentially superimposing and transferring toner images of different colors on the transfer belt or the transfer paper, and A correction pattern for correcting the color misregistration at the time of color image formation by the image processing unit is formed on the transfer belt by the image processing unit, and the correction pattern is detected by the detecting means, and the detection is performed. Correction value calculation means for calculating a correction value of a correction target driving object including the image processing unit based on the detection result of the step; and when forming a color image on the transfer belt or the transfer paper, the correction value A color image forming apparatus including: a correction unit that drives and controls the correction target driving object, and the correction pattern includes a fine adjustment pattern that finely adjusts the color misregistration, and is larger than the fine adjustment pattern. One of the two correction level correction patterns of the coarse adjustment pattern having a wide pattern interval is formed, and the correction value is calculated according to the fine adjustment pattern or coarse adjustment pattern formed. A color image forming apparatus, wherein correction is performed.   The color image forming apparatus includes a plurality of stepwise correction levels, sets the correction level based on the detection result of the correction pattern by the detection unit, and selects the correction pattern to be formed according to the correction level The color image forming apparatus according to claim 1, wherein correction of a color value is performed to perform stepwise color misregistration correction.   The color image forming apparatus includes three correction levels, a low accuracy level, a medium accuracy level, and a high accuracy level, as the plurality of correction levels, and correction processing of the three correction levels according to the degree of color misregistration. The color image forming apparatus according to claim 2, wherein:   The color image forming apparatus forms the fine adjustment pattern as the correction pattern and detects the fine adjustment pattern by the detection means. If the detection result is the low accuracy level, the coarse adjustment is used as the correction pattern. A pattern is formed, the coarse correction pattern is detected by the detection means, and a correction process having a large correction width is performed based on the correction value calculated by the correction value calculation means based on the detection result. The color image forming apparatus according to claim 3.   When the color image forming apparatus forms the fine adjustment pattern as the correction pattern and the detection result of the fine adjustment pattern detected by the detection unit is the medium accuracy level, the correction value is based on the detection result. 4. The color image forming apparatus according to claim 3, wherein correction processing is performed based on the correction value calculated by the calculation means, and the fine adjustment pattern is formed again as the correction pattern to perform correction processing.   When the color image forming apparatus forms the fine adjustment pattern as the correction pattern and the detection result obtained by detecting the fine adjustment pattern by the detection unit is the high accuracy level, the correction value is based on the detection result. 4. The color image forming apparatus according to claim 3, wherein a correction process is performed based on the correction value calculated by the calculation unit, and the correction process is terminated.   The color image forming apparatus forms the fine correction pattern as the correction pattern, and until the detection result obtained by detecting the fine adjustment pattern with the detection unit reaches the high accuracy level, the low accuracy level, the medium accuracy level, and 4. The color image forming apparatus according to claim 3, wherein the correction process of the three correction levels of the high accuracy level is repeatedly performed. The color image forming apparatus forms the fine correction pattern as the correction pattern, and until the detection result obtained by detecting the fine adjustment pattern by the detecting unit reaches the high accuracy level, the low accuracy level, the medium accuracy level, and 4. The color image forming apparatus according to claim 3, wherein the correction processing of the three high-accuracy level correction levels is repeatedly performed within a specified number of times.

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