JP4297422B2 - Color image forming apparatus and program thereof - Google Patents

Description

  The present invention relates to a color image forming apparatus such as a copying machine or a printer, and more particularly to a color image forming apparatus for correcting a positional deviation of a color image and a program thereof.

  A conventional color image forming apparatus is a so-called tandem method that obtains a color image by sequentially superimposing and transferring an image formed by an electrophotographic process onto a transfer sheet conveyed by a transfer sheet conveyance belt. is there. In this type of color image forming apparatus, in order to correct misregistration of each color, the printing operation is interrupted, and a misregistration detection pattern for detecting misregistration is formed on the conveyance belt. The pattern for use is detected by a sensor, and the positional deviation of each color is corrected. However, due to environmental changes such as temperature and humidity, changes with time, etc., the misregistration detection pattern formed on the transport belt may cause a decrease in density or density unevenness, and the misregistration detection pattern may not be formed correctly. If the misregistration detection pattern is not correctly formed, the misregistration detection pattern cannot be detected accurately, and the misregistration correction cannot be performed accurately.

  As a device that corrects the density drop and density unevenness of this misregistration detection pattern, a density detection pattern is formed on the conveyor, and this density detection pattern is detected by the density detection sensor to calculate density data. However, when the calculated density data is outside the appropriate range, a misregistration detection pattern with a corrected density is formed to perform accurate misalignment correction (see Patent Document 1).

JP-A-10-260567

  However, in the apparatus of Patent Document 1, it is necessary to always perform processing for calculating density data by detecting the density detection pattern with the density detection sensor when detecting the position deviation detection pattern. There was a problem that it took time.

The present invention has been made in view of the above-described problems of the prior art. The purpose of the present invention is to perform in advance the formation of the density detection pattern and the detection of the density of the pattern, which have been performed at the time of detecting the positional deviation detection pattern. By doing so, the positional deviation correction is performed quickly .

According to the first aspect of the present invention, a conveying unit that conveys transfer paper, a plurality of image forming units that are arranged along the conveying unit to form images of different colors, and images of each color formed by the image forming unit are provided. A transfer unit that sequentially superimposes and transfers the image onto the transfer paper, and a position at which a misregistration detection pattern for detecting a shift in the transfer position of each color image on the transfer paper is formed on the transport unit at a predetermined density. A color image forming apparatus comprising: a misalignment detection pattern forming unit; a misregistration detection unit that detects the misregistration detection pattern; and a misregistration correction unit that corrects misregistration of an image from a detection result of the misregistration detection unit. In this case, a density detection pattern for detecting the density of the image is formed between the transfer sheets on the conveying means, the density of the density detection pattern is detected, and the position deviation detection is performed from the density detection result. The process of adjusting the concentration of at use pattern formation, have lines during normal printing operation, when correcting the positional deviation, formation of the density detecting pattern, density detection of the pattern, and for the positional deviation detection without adjusting the concentration of the pattern formation, a color image forming apparatus having means for controlling the so that to form a pre-normal printing operation misregistration detection pattern by adjusting concentrations in.

According to a second aspect of the present invention, a conveying unit that conveys transfer paper, a plurality of image forming units that are arranged along the conveying unit to form images of different colors, and an image of each color formed by the image forming unit. A transfer unit that sequentially superimposes and transfers the image onto the transfer paper, and a misalignment detection pattern that forms on the transport unit a misalignment detection pattern for detecting a shift in the transfer position of each color image onto the transfer paper. A color having a forming unit, a misregistration detecting unit for detecting a misregistration detection pattern of a predetermined misregistration detection reference value, and a misregistration correcting unit for correcting the misregistration of an image from the detection result of the misregistration detection unit. In the image forming apparatus, a density detection pattern for detecting the density of the image is formed between transfer sheets on the conveying means, the density of the density detection pattern is detected, and the density detection result is The process of correcting the positional shift detection reference value of the serial position displacement detection means, have lines during normal printing operation, when correcting the positional deviation, formation of the density detecting pattern, density detection of the pattern, and without modification of the position displacement detection reference value, the color image forming having means for controlling the so that to form a misregistration detection pattern by pre-corrected positional deviation detection reference value during normal printing operation Device.

According to a third aspect of the present invention, there is provided a conveying unit that conveys transfer paper, an image forming unit that is arranged along the conveying unit to form images of different colors, and an image of each color formed by the image forming unit. A transfer unit that sequentially superimposes and transfers the image onto the transfer sheet, and a misregistration detection pattern for detecting a shift in the transfer position of each color image on the transfer sheet are formed on the transport unit under predetermined image forming conditions. A positional deviation detecting pattern forming means for detecting the positional deviation, a positional deviation detecting means for detecting the positional deviation detection pattern, and a positional deviation correcting means for correcting the positional deviation of the image from the detection result of the positional deviation detection means. In the forming apparatus, a density detection pattern for detecting the density of the image is formed between the transfer sheets on the conveyance means, the density of the density detection pattern is detected, and the detection result of the density detection means The process of calculating the image forming conditions for forming a positional deviation detection pattern, have lines during normal printing operation, when correcting the positional deviation, formation of the density detection pattern, the concentration of said pattern detection , and without performing computation of the image forming condition, a color image forming apparatus having means for controlling the so that to form a misregistration detection pattern by pre-forming condition calculated during normal printing operation is there.

According to a fourth aspect of the present invention, there is provided a conveying unit that conveys a transfer sheet, a plurality of image forming units that are arranged along the conveying unit and that form images of different colors, and images of each color formed by the image forming unit. A transfer unit that sequentially superimposes and transfers the image onto the transfer sheet, and a misregistration detection pattern for detecting a shift in the transfer position of each color image on the transfer sheet are formed on the transport unit under predetermined image forming conditions. A positional deviation detecting pattern forming means for detecting the positional deviation, a positional deviation detecting means for detecting the positional deviation detection pattern, and a positional deviation correcting means for correcting the positional deviation of the image from the detection result of the positional deviation detection means. In the forming apparatus, a density detection pattern for detecting the density of the image is formed between the transfer sheets on the conveyance means, the density of the density detection pattern is detected, and the detection result of the density detection means The processing for correcting the image forming conditions for forming a positional deviation detection pattern, have lines during normal printing operation, when correcting the positional deviation, formation of the density detection pattern, the concentration of said pattern detection , and without carrying out correction of the image forming condition, a color image forming apparatus having means for controlling the so that to form a misregistration detection pattern by the corrected image forming condition during advance of normal printing operation is there.

According to a fifth aspect of the present invention, there is provided a conveying unit that conveys the transfer paper, an image forming unit that is arranged along the conveying unit to form images of different colors, and an image of each color formed by the image forming unit. A transfer unit that sequentially superimposes and transfers the image onto the transfer paper, and a position at which a misregistration detection pattern for detecting a shift in the transfer position of each color image on the transfer paper is formed on the transport unit at a predetermined density. A color image forming apparatus comprising: a misalignment detection pattern forming unit; a misregistration detection unit that detects the misregistration detection pattern; and a misregistration correction unit that corrects misregistration of an image from a detection result of the misregistration detection unit. A density detection pattern for detecting the density of the image is formed between the transfer sheets on the conveying means, the density of the density detection pattern is detected, and the density detection result is detected. The processing for adjusting the density at the time of forming the misregistration detection pattern is performed during a normal printing operation, and when correcting the misregistration, the density detection pattern formation, the density detection of the pattern, and the position are performed. This is a control program for controlling to form a position deviation detection pattern with the density adjusted during the normal printing operation in advance without adjusting the density when forming the deviation detection pattern .
According to a sixth aspect of the present invention, a conveying unit that conveys transfer paper, a plurality of image forming units that are arranged along the conveying unit to form images of different colors, and an image of each color formed by the image forming unit. A transfer unit that sequentially superimposes and transfers the image onto the transfer paper, and a misalignment detection pattern that forms on the transport unit a misalignment detection pattern for detecting a shift in the transfer position of each color image onto the transfer paper. A color having a forming unit, a misregistration detecting unit for detecting a misregistration detection pattern of a predetermined misregistration detection reference value, and a misregistration correcting unit for correcting the misregistration of an image from the detection result of the misregistration detection unit. A control program for an image forming apparatus, wherein a density detection pattern for detecting the density of an image is formed between transfer sheets on a conveying means, the density of the density detection pattern is detected, and the density is detected. The processing for correcting the misregistration detection reference value of the misregistration detection means from the detection result is performed during normal printing operation, and when correcting the misregistration, the formation of the density detection pattern, the density of the pattern It is a control program for performing control so as to form a misregistration detection pattern based on a misregistration detection reference value corrected during a normal printing operation in advance without performing detection and correction of the misregistration detection reference value.
According to a seventh aspect of the present invention, there is provided a conveying unit that conveys a transfer sheet, a plurality of image forming units that are arranged along the conveying unit to form images of different colors, and an image of each color formed by the image forming unit. A transfer unit that sequentially superimposes and transfers the image onto the transfer sheet, and a misregistration detection pattern for detecting a shift in the transfer position of each color image on the transfer sheet are formed on the transport unit under predetermined image forming conditions. A positional deviation detecting pattern forming means for detecting the positional deviation, a positional deviation detecting means for detecting the positional deviation detection pattern, and a positional deviation correcting means for correcting the positional deviation of the image from the detection result of the positional deviation detection means. A control program for a forming apparatus, wherein a density detection pattern for detecting the density of an image is formed between transfer sheets on a conveying means, the density of the density detection pattern is detected, and the density detection A process of calculating an image forming condition when forming a misregistration detection pattern from the detection result of the stage is performed during a normal printing operation, and when correcting the misregistration, the formation of the density detection pattern, This is a control program for controlling to form a pattern for detecting misregistration according to the image forming conditions calculated during the normal printing operation in advance without performing pattern density detection and calculation of the image forming conditions.
According to an eighth aspect of the present invention, a conveying unit that conveys transfer paper, a plurality of image forming units that are arranged along the conveying unit to form images of different colors, and an image of each color formed by the image forming unit. A transfer unit that sequentially superimposes and transfers the image onto the transfer sheet, and a misregistration detection pattern for detecting a shift in the transfer position of each color image on the transfer sheet are formed on the transport unit under predetermined image forming conditions. A positional deviation detecting pattern forming means for detecting the positional deviation, a positional deviation detecting means for detecting the positional deviation detection pattern, and a positional deviation correcting means for correcting the positional deviation of the image from the detection result of the positional deviation detection means. A control program for a forming apparatus, wherein a density detection pattern for detecting the density of an image is formed between transfer sheets on a conveying means, the density of the density detection pattern is detected, and the density detection The processing for correcting the image forming condition when forming the misregistration detection pattern from the detection result of the stage is performed during a normal printing operation, and when the misregistration is corrected, the formation of the density detection pattern, the pattern This is a control program that controls to form a misregistration detection pattern according to the image forming conditions corrected during the normal printing operation in advance without performing the density detection and correction of the image forming conditions.

Effects corresponding to claims 1 and 5 : When performing positional deviation correction by performing density detection pattern formation, density detection of the pattern, and density adjustment of the positional deviation detection pattern during normal printing in advance, The formation of the density detection pattern, the density detection of the pattern, and the density adjustment of the position deviation detection pattern are not required, and the position deviation correction time can be shortened.
The effects corresponding to claims 2 and 6 are: misregistration by forming a density detection pattern, detecting the density of the pattern, and correcting the misregistration detection reference value of the misregistration detection pattern during normal printing in advance. When correction is performed, it is not necessary to form a density detection pattern, to detect the density of the pattern, and to correct the positional deviation detection reference value of the positional deviation detection pattern, thereby shortening the positional deviation correction time .
Effects corresponding to Claims 3 and 7: The positional deviation correction is performed by performing the density detection pattern formation, the density detection of the pattern, and the calculation of the image forming condition of the positional deviation detection pattern at the time of normal printing in advance. When performing this, it is not necessary to form a density detection pattern, to detect the density of the pattern, and to calculate an image forming condition for the position shift detection pattern, thereby shortening the position shift correction time.
Effects corresponding to Claims 4 and 8: Forming a density detection pattern, detecting the density of the pattern, and correcting the image forming condition of the position deviation detection pattern at the time of normal printing in advance, thereby correcting the position deviation. When performing, it is unnecessary to form a density detection pattern, to detect the density of the pattern, and to correct the image forming conditions of the position shift detection pattern, and to shorten the position shift correction time.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an embodiment of a color image forming apparatus of the present invention, and shows an example applied to a color copying machine. Y, M, C, and K after the reference numerals in the figure correspond to yellow, magenta, cyan, and black, respectively. As shown in FIG. 1, the four image forming units 1Y, 1M, 1C, and 1K that form different colors are arranged on a straight line along the conveyance belt 8 that conveys the transfer paper 10. Each of the image forming units 1Y, 1M, 1C, and 1K includes photosensitive drums 2Y, 2M, 2C, and 2K that function as image forming media, and charging units disposed around the photosensitive drums 2Y, 2M, 2C, and 2K. The apparatuses 3Y, 3M, 3C, and 3K, the exposure apparatuses 4Y, 4M, 4C, and 4K, the developing apparatuses 5Y, 5M, 5C, and 5K, and the cleaning apparatuses 6Y, 6M, 6C, and 6K are configured.

  The conveyor belt 8 suspended between the driving roller 9A and the driven roller 9B is rotationally driven in the direction of arrow A by the driving roller 9A. Then, after the surfaces of the photosensitive drums 2Y, 2M, 2C, and 2K are uniformly charged by the charging devices 3Y, 3M, 3C, and 3K, the images are to be output by the exposure devices 4Y, 4M, 4C, and 4K. Exposure is performed with a corresponding pattern, and electrostatic latent images are formed on the surfaces of the photosensitive drums 2Y, 2M, 2C, and 2K. The electrostatic latent images formed on the photosensitive drums 2Y, 2M, 2C, and 2K are developed by the developing devices 5Y, 5M, 5C, and 5K to form toner images of the respective colors. Then, the transfer paper 10 is sent out from the paper feed tray 11 and sequentially passes through the image forming units 1Y, 1M, 1C, and 1K by the conveyor belt 8, and the photosensitive drums 2Y are transferred at the transfer positions 7Y, 7M, 7C, and 7K. The toner images of the respective colors formed on 2M, 2C, and 2K are sequentially transferred and superimposed on the transfer paper 10 by the transfer devices 13Y, 13M, 13C, and 13K, thereby obtaining one color image. The transfer paper 10 onto which the four color toner images have been transferred is separated from the conveying belt 8 and fixed by the fixing device 12. The toner remaining on the surface of each of the photosensitive drums 2Y, 2M, 2C, and 2K after the transfer of the toner images of the respective colors formed on the photosensitive drums 2Y, 2M, 2C, and 2K is thereafter cleaned by the cleaning devices 6Y, 6M, It is removed by 6C and 6K to prepare for the next image forming cycle.

FIG. 2 is a perspective view of the conveyance belt 8 and the photosensitive drums 2Y, 2M, 2C, and 2K for each color of the color image forming apparatus. In FIG. 2, an arrow X indicates the main scanning direction in a direction perpendicular to the moving direction of the conveyor belt 8. An arrow Y indicates the sub-scanning direction in a direction parallel to the moving direction of the conveyor belt 8.
FIG. 3 is a perspective view of the conveyance belt 8 on which a misregistration detection pattern is formed and the misregistration detection device. In FIG. 3, misregistration detection patterns 201 and 203 transferred to both ends in the width direction (main scanning direction) on the conveyor belt 8 are detection devices 14 and 15 each having a light reflection type sensor including a light emitting portion and a light receiving portion. Is detected.

  FIG. 4 is a control block diagram of the color image forming apparatus. The block diagram of FIG. 4 includes a system controller 46, an alignment controller 45, a ROM 43, a RAM 44, an A / D converter 41, a print number counter 47, a temperature sensor 48, and the like. The ROM 43 stores a system program for the color image forming apparatus and various data necessary for executing the system program, in particular, a misregistration correction processing program and a prior density detection processing program incorporated in the system program. For example, data necessary for executing the operation, such as a positional deviation detection reference voltage and a reference density are stored. The system controller 46, the alignment controller 45, the ROM 43, and the RAM 44 constitute a computer of the color image forming apparatus.

  The RAM 44 is used as a working memory or the like by the system controller 46 and stores various data. The system controller 46 uses the RAM 44 as a working memory based on a system program in the ROM 43, controls each part of the color image forming apparatus, executes a sequence as the color image forming apparatus, and performs misregistration correction processing. And prior concentration detection processing is performed. The A / D converter 41 converts the analog signals of the misregistration detection patterns 201 and 203 detected by the detection devices 14 and 15 into digital signals and outputs them to the alignment controller 45.

  The printed sheet counter 47 operates under the control of the system controller 46 and counts the number of printed sheets. That is, the system controller 46 increments the count value of the print number counter 47 by one each time one transfer sheet 10 is conveyed from the paper feed tray 11. The temperature sensor 48 detects the temperature of the color image forming apparatus and outputs the detection result to the alignment controller 45.

  When the printing number counter 47 exceeds the reference number set in advance in the ROM 43 and the temperature detected by the temperature sensor 48 exceeds the reference temperature set in the ROM 43 during printing, the alignment controller 45 determines that the system controller 46 A misalignment correction execution request is transmitted to. The system controller 46 interrupts printing in the color image forming apparatus and controls each of the image forming units 1Y, 1M, 1C, and 1K (FIG. 1) to detect misregistration detection patterns 201 and 203 (see FIG. 1). 3), and the formed misalignment detection patterns 201 and 203 are detected by the detection devices 14 and 15.

  The alignment controller 45 uses the voltage values acquired via the A / D converter 41 based on the data stored in the RAM 44 in accordance with the calculation method stored in the ROM 43, and the positional shifts of the misalignment detection patterns 201 and 203. The amount of skew is calculated, the amount of skew deviation, the amount of main scanning registration deviation, the amount of main scanning magnification deviation, the amount of sub-scanning registration deviation, and the amount of correction are calculated, and the exposure apparatuses 4Y to 4K of the image forming units 1Y, 1M, 1C, 1K The setting values of the control signals such as the write clock and the write timing are output to the system controller 46. Based on the set values of the control signals such as the write clock and the write timing input from the alignment controller 45, the system controller 46 changes the set values of the write clock and the write timing to change the color of each color. A misalignment correction process is executed.

  FIG. 5 is a plan view showing details of misregistration detection patterns 201 and 203 formed on the conveyor belt 8. As shown in FIG. 5, the detection pattern 203 formed on the conveying belt 8 on the rear side of the image forming apparatus has a start mark Msr of black K as the head and 4d of 4 pitches of the pitch d between the marks. After the interval, eight sets of marks are sequentially formed with a set pitch (constant pitch) 7d + A + c within one circumference of the conveyor belt 8. In this embodiment, this set pitch is 3/4 of the circumference of the photosensitive drums 2Y to 2K having the same diameter, and 8 sets including the start mark Msr, a total of 65 marks are formed on the conveyor belt 8. It is formed within one circumference.

  The first mark set includes an orthogonal mark group parallel to the main scanning direction X and an oblique mark group forming an angle of 45 ° with the main scanning direction X. The orthogonal mark group includes a first orthogonal mark Akr for black K, a second orthogonal mark Ayr for yellow Y, a third orthogonal mark Acr for cyan C, and a fourth orthogonal mark Amr for magenta M. The oblique mark group is composed of a first oblique mark Bkr for K, a second oblique mark Byr for Y, a third oblique mark Bcr for C, and a fourth oblique mark Bmr for M. . The contents of the second to eighth mark sets are the same as the first mark set. On the front side, the same pattern as the rear side pattern is formed at the same time. Of the symbols attached to the marks included in these patterns, the suffix r indicates the rear side, and f indicates the front side.

  6A is an enlarged time chart showing a part of the time chart of the detection signals of the detection devices 14 and 15 (FIG. 5), and FIG. 6B is an alignment controller in which the A / D conversion data of the detection signals is aligned. It is a time chart which extracts and shows only the range written in 45 (FIG. 4). In FIG. 6A, the position of 5V is the output value of the conveyor belt 8 only, and the marks of the respective colors of the misregistration detection patterns 201 and 203 (FIG. 5) pass through the detection devices 14 and 15 so that the vicinity is 0V. The output level changes. When the output values of the detection devices 14 and 15 are continuously output for a certain time or more after the output level equal to or lower than the detection reference voltage X [V], it is assumed that the misregistration detection marks 201 and 202 have passed, Start detection.

  When the detection signals of the detection devices 14 and 15 change between high and low as shown in FIG. 6 (a), the alignment controller 45 has a range of 2V to 3V shown in FIG. 6 (b). Only digital data is stored with the sampling number value Nos. As shown in FIG. 6B, the midpoint between the center position “a” of the descending region where the level of the detection signal is falling and the center position “b” of the ascending region that is rising next is within the range of 2V to 3V. Akrp is detected as the center position of one mark Akr in the Y direction, and similarly, the center position c of the descending region where the level of the detection signal that appears next to the mark Akr is lowered, and the next rising ascent An intermediate point Ayrp of the center position d of the area is detected as the center position of the other mark Ayr in the Y direction.

  FIG. 7 is a plan view showing the prior density detection patterns 50A and 50B formed between the transfer sheets 10A and 10B conveyed on the conveyance belt 8. FIG. The prior density detection pattern 50A is separated from the rear end of the transfer paper 10A on the front side in the transport direction of the transport belt 8 by a distance d and is formed between the subsequent transfer paper 10B. The prior density detection pattern 50B is formed at a distance d from the rear end of the subsequent transfer paper 10B. As described above, the misregistration correction is performed by interrupting the normal printing operation when the number of printed sheets exceeds the reference number and the temperature of the image forming apparatus exceeds the reference value. The above-described misregistration detection patterns 201 and 203 and density detection patterns (not shown) for adjusting the density of the misregistration detection patterns 201 and 203 are formed on the transport conveyor 8. By using this density detection pattern creation function of the system controller 46, during normal printing on the transfer papers 10A, 10B, the transfer belts 10A, 10B that are transported on the transport belt 8 are conveyed in advance on the transport belt 8. Density detection patterns 50A and 50B are formed. Then, during normal printing, the densities of the prior density detection patterns 50A and 50B are detected by the detection device 14, and based on the detection results, the positional deviation detection patterns 201 and 203 are normal before executing the positional deviation correction operation. Preparation for forming with a high density or preparation on the side of the detection devices 14 and 15 for correctly detecting the misregistration detection patterns 201 and 203 are made ready.

  FIG. 8 is a flowchart of the first embodiment showing the detection process of the prior density detection pattern. The alignment controller 45 determines whether or not there is a density detection pattern creation request. If there is a density detection pattern creation request (YES in S101), the printing operation is interrupted and the density detection pattern is placed on the transport conveyor 8. A pattern is formed (S102), and its density is detected by the detection device 14 (S103). If it is necessary to adjust the density, misregistration detection patterns 201 and 203 with adjusted density are formed on the conveyor 8. Then, the positional deviation of the positional deviation detection patterns 201 and 20 is detected, and if there is a positional deviation, the positional deviation is corrected.

  If there is no request for density detection pattern creation (NO in S101), prior density detection patterns 50A and 50B are formed on the conveyance belt 8 between the transfer sheets 10 on which the printing operation is performed during a normal printing operation. Is formed (S104). The detection device 14 detects the densities of the prior density detection patterns 50A and 50B (S105), and transmits the detection values D (V) of the densities of the prior density detection patterns 50A and 50B to the system controller 46 (S106). If the system controller 46 determines from the detection value D (V) that the density of the prior density detection patterns 50A and 50B needs to be adjusted (S107, YES), it sets a density adjustment execution flag (S108). If it is determined that the density adjustment of the prior density detection patterns 50A and 50B is unnecessary (S107, NO), the density adjustment execution flag is reset (S109). Thereafter, the printing operation in the image forming apparatus proceeds, and when the number of printed sheets exceeds the reference number and the temperature of the image forming apparatus exceeds the reference temperature, the printing operation is interrupted to perform misalignment correction. If the density adjustment execution flag is set, the misregistration detection patterns 201 and 203 with the density adjusted are formed on the conveyor 8 and the misalignment correction operation is executed. Therefore, it is not necessary to perform a process of calculating density data by forming a density detection pattern during the positional deviation correction operation, so that the positional deviation correction operation can be performed quickly.

  FIG. 9 is a flowchart of the second embodiment showing the detection process of the prior density detection pattern. The alignment controller 45 determines whether or not there is a density detection pattern creation request. If there is a density detection pattern creation request (YES in S201), the printing operation is interrupted and the density detection pattern is placed on the transport conveyor 8. A pattern is formed (S202), the density is detected by the detection device 14 (S203), and if it is necessary to adjust the density, misregistration detection patterns 201 and 203 with adjusted density are formed on the conveyor 8. Then, the positional deviation of the positional deviation detection patterns 201 and 20 is detected, and if there is a positional deviation, the positional deviation is corrected.

  If there is no request for density detection pattern creation (NO in S201), prior density detection patterns 50A and 50B are formed on the conveyance belt 8 between the transfer sheets 10 on which the printing operation is being performed during a normal printing operation. Is formed (S204). The detection device 14 detects the densities of the prior density detection patterns 50A and 50B (S205), and the system controller 46 detects the detection value D (V) of the prior density detection patterns 50A and 50B and the positional deviation detection reference voltage X (V). (S206), and if the difference is greater than or equal to S (V) (S206, YES), the detection reference voltage X (V) is not changed. If the difference is less than or equal to S (V) (S206), a value at which the difference from the detected value D (V) is S (V) is calculated as the new detected reference voltage Xs (V), and the detected reference voltage X (V) is replaced with the new detection reference voltage Xs (V) (S207). Thereafter, the printing operation in the image forming apparatus proceeds, and when the number of printed sheets exceeds the reference number and the temperature of the image forming apparatus exceeds the reference temperature, the printing operation is interrupted to perform misalignment correction. Since the misregistration detection reference voltage is replaced with the new detection reference voltage Xs (V), the misregistration detection patterns 201 and 203 are correctly detected without adjusting the density of the misregistration detection patterns 201 and 203. It can be carried out.

  FIG. 10 is a flowchart of the third embodiment showing the detection process of the prior density detection pattern. The alignment controller 45 determines whether or not there is a density detection pattern creation request. If there is a density detection pattern creation request (YES in S301), the printing operation is interrupted and the density detection pattern is placed on the transport conveyor 8. A pattern is formed (S302), the density is detected by the detection device 14 (S303), and if it is necessary to adjust the density, misregistration detection patterns 201 and 203 with adjusted density are formed on the conveyor 8. Then, the positional deviation of the positional deviation detection patterns 201 and 20 is detected, and if there is a positional deviation, the positional deviation is corrected.

  If there is no request for density detection pattern creation (NO in S301), prior density detection patterns 50A and 50B are formed on the conveyance belt 8 between the transfer sheets 10 on which the printing operation is performed during a normal printing operation. Is formed (S304). The detection device 14 detects the densities of the prior density detection patterns 50A and 50B (S305), and transmits the detection values D (V) of the densities of the prior density detection patterns 50A and 50B to the system controller 46 (S306). The system controller 46 calculates the optimum value of the image forming condition including the charging bias, the developing bias, the transfer bias, and the writing light amount for forming the misregistration detection patterns 201 and 203 from the detection value D (V) (S307). ). Thereafter, the printing operation in the image forming apparatus proceeds, and when the number of printed sheets exceeds the reference number and the temperature of the image forming apparatus exceeds the reference temperature, the printing operation is interrupted to perform misalignment correction. Since the misregistration detection patterns 201 and 203 are formed under the optimum image forming conditions calculated during normal printing, the misregistration detection patterns 201 and 203 can be correctly detected.

  FIG. 11 is a flowchart of the fourth embodiment showing the detection process of the prior density detection pattern. The alignment controller 45 determines whether or not there is a density detection pattern creation request. If there is a density detection pattern creation request (YES in S401), the printing operation is interrupted and the density detection pattern is placed on the transport conveyor 8. A pattern is formed (S402), its density is detected by the detection device 14 (S403), and if it is necessary to adjust the density, misregistration detection patterns 201 and 203 with adjusted density are formed on the conveyor 8. Then, the positional deviation of the positional deviation detection patterns 201 and 20 is detected, and if there is a positional deviation, the positional deviation is corrected.

  If there is no request for density detection pattern creation (NO in S401), prior density detection patterns 50A and 50B are formed on the conveyance belt 8 between the transfer sheets 10 on which the printing operation is performed during a normal printing operation. Is formed (S404). The detection device 14 detects the prior density detection patterns 50A and 50B (S405), and transmits the detection values D (V) of the prior density detection patterns 50A and 50B to the system controller 46 (S406). When the detected value D (V) is equal to or less than a predetermined threshold value Dt (V) (S407, YES), the system controller 46 determines the position deviation detection patterns 201 and 203 that have already been set. The image forming conditions are corrected (S408). Thereafter, the printing operation in the image forming apparatus proceeds, and when the number of printed sheets exceeds the reference number and the temperature of the image forming apparatus exceeds the reference temperature, the printing operation is interrupted to perform misalignment correction. Since the misregistration detection patterns 201 and 203 are formed under the optimum image forming conditions corrected at the time of normal printing, the misregistration detection patterns 201 and 203 can be correctly detected.

  Although the color image forming apparatus according to the embodiment of the present invention has been described above, a series of procedures for executing the prior density detection process, that is, the image density during the transfer operation to the transfer paper on the computer of the color image forming apparatus is described. The procedure for forming a density detection pattern for detecting the density between transfer sheets on the conveying means, the procedure for detecting the density of the density detection pattern, and the density at the time of forming the misregistration detection pattern from the density detection result. By recording a program for executing the adjustment procedure on a computer-readable recording medium such as a flexible disk, a CD-ROM, a DVD-ROM, and an MO, and causing the computer of the color image forming apparatus to read the program, The prior concentration detection process according to the present invention can be easily performed. In addition to recording the program on a recording medium, the program can be directly read by a computer of a color image forming apparatus via an arbitrary network such as the Internet or an intranet.

FIG. 1 is a schematic configuration diagram showing an embodiment of a color image forming apparatus of the present invention. FIG. 2 is a perspective view of the conveyance belt and the photosensitive drums of the respective colors. FIG. 3 is a perspective view of the conveyance belt on which the misregistration detection pattern is formed and the misregistration detection device. FIG. 4 is a control block diagram of the color image forming apparatus. FIG. 5 is a plan view showing details of a misregistration detection pattern formed on the conveyor belt. FIG. 6A is a time chart of a detection signal of the detection device, and FIG. 6B is a time chart showing only a range in which A / D conversion data of the detection signal is written in the alignment controller 45. FIG. FIG. 7 is a plan view of a prior density detection pattern formed on the transport belt. FIG. 8 is a flowchart of the first embodiment showing the detection process of the prior density detection pattern. FIG. 9 is a flowchart of the second embodiment showing the detection process of the prior density detection pattern. FIG. 10 is a flowchart of the third embodiment showing the detection process of the prior density detection pattern. FIG. 11 is a flowchart of the fourth embodiment showing the detection process of the prior density detection pattern.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1Y, 1M, 1C, 1K ... Image formation part, 2Y, 2M, 2C, 2K ... Photosensitive drum, 8 ... Conveyor belt, 10 ... Transfer paper, 14, 15 ... Detection apparatus , 43... ROM, 44... RAM, 45... Alignment controller, 46... System controller, 50A, 50B .. pre-density detection pattern, 201, 203. pattern.

Claims (8)

Conveying means for conveying the transfer paper, a plurality of image forming means arranged along the conveying means for forming images of different colors, and images of the respective colors formed by the image forming means are sequentially superimposed on the transfer paper A transfer means for transferring the image, and a misregistration detection pattern forming means for forming a misregistration detection pattern for detecting a shift in the transfer position of each color image on the transfer paper at a predetermined density on the conveying means; In a color image forming apparatus comprising: a position deviation detection unit that detects the position deviation detection pattern; and a position deviation correction unit that corrects an image position deviation from a detection result of the position deviation detection unit.
A density detection pattern for detecting the density of the image is formed between the transfer sheets on the conveying means, the density of the density detection pattern is detected, and the density at the time of forming the misregistration detection pattern from the density detection result the process of adjusting the, have lines during normal printing operation, when correcting the positional deviation, the formation of the density detection pattern, the density detection of the pattern, and the concentration at the position shift detecting pattern formed adjusted without performing the color image forming apparatus having means for controlling the so that to form a pre-normal printing operation misregistration detection pattern by adjusting concentrations in. Conveying means for conveying the transfer paper, a plurality of image forming means arranged along the conveying means for forming images of different colors, and images of the respective colors formed by the image forming means are sequentially superimposed on the transfer paper A transfer means for transferring the image, a misregistration detection pattern forming means for forming a misregistration detection pattern on the conveying means for detecting a deviation of the transfer position of each color image on the transfer paper, and a predetermined position. In a color image forming apparatus having a positional deviation detection unit for detecting a positional deviation detection pattern of a deviation detection reference value and a positional deviation correction unit for correcting a positional deviation of an image from a detection result of the positional deviation detection unit.
A density detection pattern for detecting the density of the image is formed between the transfer sheets on the conveying means, the density of the density detection pattern is detected, and the positional deviation detection of the positional deviation detection means is detected from the density detection result. the processing for correcting the reference value, have lines during normal printing operation, when correcting the positional deviation, formation of the density detecting pattern, density detection of the pattern, and the correction of the positional shift detection reference value color image forming apparatus having no, means for controlling the so that to form a misregistration detection pattern by pre-corrected positional deviation detection reference value during normal printing operations be performed. Conveying means for conveying the transfer paper, a plurality of image forming means arranged along the conveying means for forming images of different colors, and images of the respective colors formed by the image forming means are sequentially superimposed on the transfer paper A transfer means for transferring the image and a misregistration detection pattern formation for forming a misregistration detection pattern for detecting a shift in the transfer position of each color image on the transfer paper on the conveying means under a predetermined image forming condition. In a color image forming apparatus, comprising: a positional deviation detection unit that detects the positional deviation detection pattern; and a positional deviation correction unit that corrects the positional deviation of the image from the detection result of the positional deviation detection unit.
A density detection pattern for detecting the density of the image is formed between the transfer sheets on the conveyance means, the density of the density detection pattern is detected, and a position deviation detection pattern is formed from the detection result of the density detection means. the process of calculating the image forming conditions for, have rows during normal printing operation, when correcting the positional deviation, formation of the density detecting pattern, density detection of the pattern, and the imaging condition calculated without performing the color image forming apparatus having means for controlling the so that to form a misregistration detection pattern by pre-forming condition calculated during normal printing operations. Conveying means for conveying the transfer paper, a plurality of image forming means arranged along the conveying means for forming images of different colors, and images of the respective colors formed by the image forming means are sequentially superimposed on the transfer paper A transfer means for transferring the image and a misregistration detection pattern formation for forming a misregistration detection pattern for detecting a shift in the transfer position of each color image on the transfer paper on the conveying means under a predetermined image forming condition. In a color image forming apparatus, comprising: a positional deviation detection unit that detects the positional deviation detection pattern; and a positional deviation correction unit that corrects the positional deviation of the image from the detection result of the positional deviation detection unit.
A density detection pattern for detecting the density of the image is formed between the transfer sheets on the conveyance means, the density of the density detection pattern is detected, and a position deviation detection pattern is formed from the detection result of the density detection means. the processing for correcting the image forming conditions for, have rows during normal printing operation, when correcting the positional deviation, formation of the density detecting pattern, density detection of the pattern, and the imaging condition correction without performing the color image forming apparatus having means for controlling the so that to form a misregistration detection pattern by the corrected image forming condition during advance of normal printing operation. Conveying means for conveying the transfer paper, a plurality of image forming means arranged along the conveying means for forming images of different colors, and images of the respective colors formed by the image forming means are sequentially superimposed on the transfer paper A transfer means for transferring the image, and a misregistration detection pattern forming means for forming a misregistration detection pattern for detecting a shift in the transfer position of each color image on the transfer paper at a predetermined density on the conveying means; A control program for a color image forming apparatus , comprising: a misregistration detection unit that detects the misregistration detection pattern; and a misregistration correction unit that corrects misregistration of an image from a detection result of the misregistration detection unit .
A density detection pattern for detecting the density of the image is formed between the transfer sheets on the conveying means, the density of the density detection pattern is detected, and the density at the time of forming the misregistration detection pattern from the density detection result Is performed during a normal printing operation, and when correcting the positional deviation, the density detection pattern is formed, the density of the pattern is detected, and the density is adjusted when the positional deviation detection pattern is formed. A control program for performing control so as to form a misregistration detection pattern with a density adjusted during a normal printing operation in advance . Conveying means for conveying the transfer paper, a plurality of image forming means arranged along the conveying means for forming images of different colors, and images of the respective colors formed by the image forming means are sequentially superimposed on the transfer paper A transfer means for transferring the image, a misregistration detection pattern forming means for forming a misregistration detection pattern on the conveying means for detecting a deviation of the transfer position of each color image on the transfer paper, and a predetermined position. A control program for a color image forming apparatus, comprising: a misregistration detection unit that detects a misregistration detection pattern of a misregistration detection reference value; and a misregistration correction unit that corrects an image misregistration from a detection result of the misregistration detection unit. There,
A density detection pattern for detecting the density of the image is formed between the transfer sheets on the conveying means, the density of the density detection pattern is detected, and the positional deviation detection of the positional deviation detection means is detected from the density detection result. The process of correcting the reference value is performed during a normal printing operation, and when correcting the positional deviation, the density detection pattern is formed, the density of the pattern is detected, and the positional deviation detection reference value is corrected. And a control program for performing control so as to form a misregistration detection pattern based on a misregistration detection reference value corrected during a normal printing operation in advance. Conveying means for conveying the transfer paper, a plurality of image forming means arranged along the conveying means for forming images of different colors, and images of the respective colors formed by the image forming means are sequentially superimposed on the transfer paper A transfer means for transferring the image and a misregistration detection pattern formation for forming a misregistration detection pattern for detecting a shift in the transfer position of each color image on the transfer paper on the conveying means under a predetermined image forming condition. A control program for a color image forming apparatus, comprising: a position detection means for detecting a position shift detection pattern; and a position shift correction means for correcting a position shift of an image from a detection result of the position shift detection means. And
A density detection pattern for detecting the density of the image is formed between the transfer sheets on the conveyance means, the density of the density detection pattern is detected, and a position deviation detection pattern is formed from the detection result of the density detection means. The processing for calculating the image forming conditions at the time of performing is performed during a normal printing operation, and when correcting the displacement, the formation of the density detection pattern, the density detection of the pattern, and the calculation of the image forming conditions are performed. A control program for performing control so as to form a misregistration detection pattern according to image forming conditions calculated during a normal printing operation in advance. Conveying means for conveying the transfer paper, a plurality of image forming means arranged along the conveying means for forming images of different colors, and images of the respective colors formed by the image forming means are sequentially superimposed on the transfer paper A transfer means for transferring the image and a misregistration detection pattern formation for forming a misregistration detection pattern for detecting a shift in the transfer position of each color image on the transfer paper on the conveying means under a predetermined image forming condition. A control program for a color image forming apparatus, comprising: a position detection means for detecting a position shift detection pattern; and a position shift correction means for correcting a position shift of an image from a detection result of the position shift detection means. And
A density detection pattern for detecting the density of the image is formed between the transfer sheets on the conveyance means, the density of the density detection pattern is detected, and a position deviation detection pattern is formed from the detection result of the density detection means. The processing for correcting the image forming conditions at the time of performing is performed during a normal printing operation, and when correcting the positional deviation, formation of the density detection pattern, density detection of the pattern, and correction of the image forming conditions are performed. A control program for performing control so that a misregistration detection pattern is formed according to an image forming condition corrected during a normal printing operation in advance.

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