JP2005165220A - Color image forming apparatus and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color image forming apparatus and an image forming method capable of drastically shortening an operation time related to correction processing upon image formation and reducing the number of times of execution of color slippage correction mode. <P>SOLUTION: The color image forming apparatus which executes the color slippage correction mode and a color slippage confirmation mode is provided with an image forming means 60 which has a photoreceptor drum and an intermediate transfer belt and forms a color image on the intermediate transfer belt, a color slippage detection section 64 which detects the color image formed by the image forming means 60 and a system control section 15 which executes other correction modes related to image formation processing other than the color slippage correction mode, controls the image forming means 60 so as to execute the color slippage confirmation mode succeeding to the other correction mode and discriminates whether the color slippage correction mode is executed or not based on the detection result of the image for color slippage confirmation detected by the color slippage detection section 64. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus and an image forming method suitable for application to a tandem type color printer or color copying machine having an intermediate transfer belt or a transfer material conveying belt, a color complex machine thereof, or the like.

  In recent years, tandem type color printers, copiers, and complex machines of these are often used. In these color image forming apparatuses, yellow (Y), magenta (M), cyan (C), and black (BK) exposure means, developing means, photosensitive drums, and intermediate transfer belts or conveying material transfer belts are used. And a fixing device.

  For example, the Y-color exposure means draws an electrostatic latent image on the photosensitive drum based on arbitrary image information. In the developing device, a color toner image is formed by attaching a Y-color toner to the electrostatic latent image drawn on the photosensitive drum. The photosensitive drum transfers the toner image to the intermediate transfer belt. Similar processing is performed for the other M, C, and BK colors. The color toner image transferred to the intermediate transfer belt is transferred to a sheet and then fixed by a fixing device.

  According to this image forming apparatus, in order to maintain optimum color image formation quality, yellow (Y), magenta (M), cyan (C), and black that reproduce the R, G, and B colors of the original image. (Bk) It is essential to correct the image forming means so as not to cause color misregistration between colors (hereinafter referred to as color misregistration correction mode). Color misregistration generally occurs due to assembly tolerances of the writing unit, the photosensitive drum, and the intermediate transfer belt. Also, due to changes in the outside air temperature and the temperature inside the machine due to continuous use, the support means such as the exposure means, the photosensitive drum, and the intermediate transfer belt expands and contracts over time, and this occurs due to this. I think that.

  Regarding the above-described color misregistration correction mode, a registration mark formed on the intermediate transfer belt or the conveyance material transfer belt is detected by a detection unit (hereinafter referred to as a color misregistration detection sensor) for detecting color misregistration such as a reflection type sensor. Deviation amounts of main scanning, sub-scanning, lateral magnification, and skew relating to registration marks of other colors with respect to the reference color are calculated, and color deviation is corrected by adjusting image formation timing and the like.

  In relation to this type of color misregistration correction function, Patent Document 1 discloses an image forming apparatus and an image color misregistration adjustment method. According to this image forming apparatus, the temperature sensor, the image forming unit, and the system control unit are provided, and the system control unit that has input the temperature detection data from the temperature sensor determines when to perform the color misregistration adjustment. When it arrives, color misregistration adjustment is executed through the image forming unit. In this way, color misalignment adjustment is not performed more than necessary, and an optimal image can always be formed.

  Patent Document 2 discloses an image forming apparatus. According to this image forming apparatus, the temperature detection unit and the plurality of correction control units are provided, and the temperature detection unit detects the temperature inside or near the scanning optical device and outputs the detected temperature to the correction control unit. The correction control means compares a preset threshold value with a temperature difference, and when the temperature difference becomes equal to or less than the threshold value, it predicts a positional deviation on the scanning surface and corrects the color deviation. With this configuration, the throughput can be maintained at a reasonable value.

Japanese Patent Application Laid-Open No. 08-286656 (page 4, FIG. 6) JP 2000-218860 A (3rd page, Fig. 4)

  However, the conventional tandem type color image forming apparatus has the following problems.

  i. According to Japanese Patent Laid-Open No. 2004-260260, the timing for executing the color misregistration adjustment is determined based on the detected temperature, but since it is executed independently for the process correction operation, A fall-down process after the color misregistration adjustment is required. For this reason, the correction operation time becomes long, and the state where the apparatus cannot be used becomes long.

  ii. According to Patent Document 2, every time the temperature difference becomes equal to or less than the threshold value, the color shift correction is performed by predicting the position shift on the scanning plane. Therefore, depending on the use situation, the color shift adjustment is frequently performed. There is a possibility that the user may not use the toner member and the toner member may be wasted.

  iii. According to Patent Documents 1 and 2, a temperature sensor is arranged in a writing unit, and the temperature in the unit is detected to correct color misregistration. In general, it is known that the color misregistration is caused by the temperature rise of the member that supports the image forming unit and the intermediate transfer member. Therefore, it is difficult to predict the color misregistration correction amount only by detecting the temperature of the writing unit.

  Accordingly, the present invention solves the above-described problems, and it is possible to greatly reduce the operation time related to the correction processing at the time of image formation and to reduce the number of executions of the color misregistration correction mode. An object is to provide an image forming apparatus and an image forming method.

  In order to solve the above problems, a first color image forming apparatus according to the present invention is a color image forming apparatus that forms an arbitrary color image on an image forming body. An image of each color is formed, the passing timing of the color misregistration correction image is read, the misregistration amount of other color images with respect to the reference color image is calculated, and the image formation position is corrected based on the misregistration amount The color shift correction mode is set to the color misregistration correction mode, and a color misregistration confirmation image for confirming whether or not to execute the color misregistration correction mode is formed on the image forming body, and the color misregistration confirmation formed on the image forming body is performed. When the operation for determining whether or not to execute the color misregistration correction mode based on the detection result of the color misregistration confirmation image is set to the color misregistration confirmation mode, the image forming body is included and Image forming hand for forming a color image on an image forming body And a detecting means for detecting a color image formed by the image forming means, and another correction mode related to the image forming process other than the color misregistration correction mode, and a color misregistration confirmation mode following the other correction mode. Control means for controlling the image forming means to execute the color misregistration correction mode based on the detection result of the color misregistration confirmation image detected by the detecting means. It is a feature.

  According to the first color image forming apparatus of the present invention, when an arbitrary color image is formed on the image forming body, the control unit performs image formation so as to execute a correction mode other than the color misregistration correction mode. Control means. For example, the control unit executes another correction mode related to the image forming process including the surface potential correction process, the maximum density correction process, and the gradation correction process of the image forming body of the image forming unit. The image forming unit forms a color image on the image forming body based on control by the control unit. The detecting means detects the color image formed by the image forming means. On the premise of this, the control means executes the color misregistration confirmation mode following the other correction modes. For example, the control unit controls the image forming unit to execute the color misregistration confirmation mode as a series of operations at the end of the other correction modes. The image forming means creates an image for checking color misregistration based on a process correction process for correcting the density condition of the color image. The control means determines whether or not to execute the color misregistration correction mode based on the detection result of the color misregistration confirmation image detected by the detecting means.

  Therefore, since the necessity of the execution can be determined before the execution of the color misregistration correction mode, it is possible to avoid a situation in which the mode is forcibly shifted to the color misregistration correction mode without the necessity of the execution. In addition, it is not necessary to execute the start-up process dedicated to the color misregistration correction mode and the fall-down process. As a result, the number of executions of the color misregistration correction mode can be greatly reduced, and the operation time related to the correction processing can be greatly shortened. In addition, the toner member is not wasted.

  A second color image forming apparatus according to the present invention is a color image forming apparatus that forms an arbitrary color image on an image forming body, forms an image of each color including a reference color for color misregistration correction on the image forming body, The color misregistration correction mode is an operation that reads the timing of passing the image for color misregistration correction, calculates the misregistration amount of another color image with respect to the reference color image, and corrects the image forming position based on the misregistration amount. When the temperature detection result is equal to or lower than a predetermined temperature, the first color misregistration correction mode is executed when the temperature detection result in the machine at the start of warm-up is compared with a predetermined temperature set in advance. The first temperature detection result and the first correction value at the time of executing the color misregistration correction mode are acquired, and a temperature at which the color misregistration error is outside the allowable range with respect to the first temperature detection result acquired here is obtained. Further detected temperature that is outside the allowable range If detected, the second color misregistration correction mode is executed, and the second temperature detection result and the second correction value at the time of executing the second color misregistration correction mode are acquired. An operation for estimating the position shift amount of another color image with respect to the reference color image using the temperature detection result 2 and the first and second correction values, and correcting the image forming position based on the position shift estimated amount. Is a color misregistration estimation correction mode, an image forming unit that has an image forming body and forms a color image on the image forming body, a temperature detecting unit that detects temperature inside the apparatus and outputs temperature detection information, and A control unit that determines whether or not to correct color misregistration based on temperature detection information output by the temperature detection unit and that corrects an image forming position in the image forming unit based on a color misregistration estimation correction mode is provided. It is a feature.

  According to the second color image forming apparatus of the present invention, when an arbitrary color image is formed on the image forming body, the temperature detecting means detects the in-machine temperature and outputs temperature detection information to the control means. The control means determines whether or not to correct the color misregistration based on the temperature detection information output by the temperature detection means. For example, the control means executes the first color misregistration correction mode when the temperature detection result in the apparatus at the start of warm-up is equal to or lower than a predetermined temperature set in advance. The image forming unit having the image forming body forms a color image on the image forming body based on the first color misregistration correction mode.

  For example, the control means further detects an in-machine temperature at which the color misregistration error is outside the allowable range with respect to the maximum value of the in-machine temperature at the time of execution of the first color misregistration correction mode updated and stored in the memory. When the in-machine temperature is detected, the second color misregistration correction mode is executed, the temperature detection result and the correction value at the time of executing the second color misregistration correction mode are stored in the memory, and thereafter stored in the memory. Using all the temperature detection results and correction values, the amount of misregistration of the other color image with respect to the reference color image is estimated, and the image forming position in the image forming unit is corrected based on the estimated amount of misregistration. .

  Therefore, when the in-machine temperature rises, the color misregistration correction mode is executed only once for the first time when the temperature exceeds the allowable temperature, and the correction value and in-machine temperature are stored when the color misregistration correction mode is executed. Since color misregistration can be corrected by data processing using the in-machine temperature and correction value acquired in advance without executing the mode, the number of execution processes of the color misregistration correction mode can be greatly reduced, which is wasteful. Thus, the toner member is not consumed.

  An image forming method according to the present invention is an image forming method in which an arbitrary color image is formed on an image forming body, an image of each color including a reference color for color misalignment correction is formed on the image forming body, and the color misalignment correcting The operation of correcting the image forming position based on the amount of misregistration is set as the color misregistration correction mode by reading the image passing timing, calculating the amount of misregistration of the other color image with respect to the reference color image, and starting the warm-up. When the temperature detection result is equal to or lower than the predetermined temperature, the first color misregistration correction mode is executed, and the first color misregistration correction mode is executed. The first temperature detection result and the first correction value at the time of execution are acquired, and the temperature at which the color misregistration error is outside the allowable range with respect to the acquired first temperature detection result is further detected, When a temperature outside the range is detected The second color misregistration correction mode is executed, the second temperature detection result and the second correction value at the time of executing the second color misregistration correction mode are acquired, and thereafter the first and second temperature detection results and the first The operation of estimating the position shift amount of another color image with respect to the reference color image using the first and second correction values and correcting the image forming position based on the position shift estimated amount is referred to as a color shift estimation correction mode. The temperature inside the machine is detected, and whether or not to correct the color misregistration is determined based on the detected result of the temperature inside the machine, and the image forming position is corrected based on the color misregistration estimation correction mode. It is characterized by.

  According to the image forming method of the present invention, when an arbitrary color image is formed on the image forming body, the color misregistration correction mode is executed only once for the first time after the allowable temperature is exceeded when the in-machine temperature rises. The correction value and in-machine temperature at the time of execution of the misregistration correction mode are stored, and thereafter, the color misregistration is corrected by data processing using the in-machine temperature and the correction value acquired in advance without executing the color misregistration correction mode. become able to. Therefore, the number of execution processes of the color misregistration correction mode can be greatly reduced, and the toner member is not wasted.

  According to the first color image forming apparatus of the present invention, the image forming unit includes a control unit that controls the image forming unit when an arbitrary color image is formed on the image forming body. Based on the detection result of the color misregistration confirmation image detected here by executing another correction mode related to the image forming process and performing the color misregistration confirmation mode following the correction mode. Whether or not to execute the color misregistration correction mode is determined.

  With this configuration, since it is possible to determine whether or not the color misregistration correction mode is necessary before the execution of the color misregistration correction mode, it is possible to avoid a situation in which the mode is forcibly shifted to the color misregistration correction mode without the necessity for the execution. . Therefore, it is not necessary to execute the start-up process dedicated to the color misregistration correction mode and the fall-down process. As a result, the number of executions of the color misregistration correction mode can be greatly reduced, and the operation time related to the correction processing can be greatly shortened. In addition, the toner member is not wasted.

  According to the second color image forming apparatus and the image forming method of the present invention, the image forming apparatus includes a control unit that controls the image forming unit when an arbitrary color image is formed on the image forming body. Whether or not to correct the color misregistration is determined based on the information, and the image forming position in the image forming unit is corrected based on the color misregistration estimation correction mode.

  With this configuration, when the internal temperature rises, the color misregistration correction mode is executed only once for the first time after exceeding the allowable temperature, and the correction value and temperature at the time of executing the color misregistration correction mode are stored. The color shift can be corrected by data processing using the correction value acquired in advance without executing the shift correction mode. As a result, the number of executions of the color misregistration correction mode can be greatly reduced, and the operation time related to the correction processing can be greatly shortened. In addition, the toner member is not wasted.

  A color image forming apparatus and an image forming method according to embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a conceptual diagram showing a configuration example of a color image forming apparatus 100 as each embodiment of the present invention.
The first embodiment includes a control unit that controls image formation when an arbitrary color image is formed on the image forming body, executes another correction mode related to image formation processing other than the color misregistration correction mode, and The image forming unit is controlled to execute the color misregistration confirmation mode following the correction mode, and it is determined whether or not to execute the color misregistration correction mode based on the detection result of the color misregistration confirmation image detected here. In this way, it is possible to determine whether or not the color misregistration correction mode is necessary before executing the color misregistration correction mode, and to greatly shorten the operation time related to the correction processing at the time of image formation.

  A color image forming apparatus 100 illustrated in FIG. 1 is an apparatus that forms a color image by superimposing colors on an image forming body based on arbitrary image information. When the color misregistration correction time is reached, a color misregistration confirmation mode is illustrated. Whether or not to execute the color misregistration correction mode is determined based on the execution of the above. Here, the color misregistration correction mode is a method of forming an image of each color including a reference color for color misregistration correction on an image forming body, reading the passing timing of the image for correcting color misregistration, and then selecting another color for the reference color image. This is an operation for calculating the amount of image displacement and correcting the image forming position based on the amount of displacement.

  The color misregistration confirmation mode is a color misregistration confirmation pattern (image) for confirming whether or not to execute the color misregistration correction mode is formed on the image forming body, and the color formed on the image forming body. An operation for detecting a misregistration confirmation pattern and determining whether or not to execute a misregistration correction mode based on the detection result of the misregistration confirmation pattern.

  The color image forming apparatus 100 includes an apparatus main body 101 and an image reading apparatus 102. An image reading device 102 including an automatic document feeder 201 and a document image scanning exposure device 202 is installed on the upper part of the apparatus main body 101. The document 30 placed on the document table of the automatic document feeder 201 is conveyed by a conveying means, and one or both sides of the document are scanned and exposed by the optical system of the document image scanning exposure device 202 to reflect the document image. Incident light is read by the line image sensor CCD.

  The analog image signal photoelectrically converted by the line image sensor CCD is subjected to analog processing, A / D conversion, shading correction, image compression processing, and the like in an image processing unit (not shown) to become digital image data. The image data is sent to image writing units (exposure means) 3Y, 3M, 3C and 3K constituting the image forming means 60.

  The automatic document feeder 201 described above is provided with automatic double-sided document conveying means. The automatic document feeder 201 continuously reads the contents of a large number of documents 30 fed from the document placement table at once, and stores the document contents in a storage means (electronic RDH function). This electronic RDH function is conveniently used when copying the contents of a large number of documents by the copying function or when transmitting a large number of documents 30 by the facsimile function.

  The apparatus main body 101 is called a tandem type color image forming apparatus. The image forming means 60 includes a plurality of sets of image forming units (image forming systems) 10Y, 10M, 10C, and 10K each having an image forming body for each color, and an endless intermediate transfer belt (image transfer) as an example of an intermediate transfer body. System) 6, a paper feeding / conveying means including a re-feeding mechanism (ADU mechanism), and a fixing device 17 for fixing the toner image.

  The image forming unit 10Y that forms a yellow (Y) image includes a photosensitive drum 1Y as an image forming body that forms a Y-color toner image, and a Y-color charging disposed around the photosensitive drum 1Y. Means 2Y, exposure means 3Y, developing device 4Y, and image forming body cleaning means 8Y. An image forming unit 10M for forming a magenta (M) color image includes a photosensitive drum 1M as an image forming body for forming an M color toner image, an M color charging unit 2M, an exposure unit 3M, and a developing device 4M. And an image forming member cleaning means 8M.

  An image forming unit 10C for forming a cyan (C) color image includes a photosensitive drum 1C as an image forming body for forming a C toner image, a charging unit 2C for C color, an exposure unit 3C, and a developing device 4C. And an image forming member cleaning means 8C. An image forming unit 10K that forms a black (BK) color image includes a photosensitive drum 1K as an image forming body that forms a BK color toner image, a charging unit 2K for BK color, an exposure unit 3K, and a developing device 4K. And an image forming member cleaning means 8K.

  The charging unit 2Y and the exposure unit 3Y, the charging unit 2M and the exposure unit 3M, the charging unit 2C and the exposure unit 3C, and the charging unit 2K and the exposure unit 3K constitute a latent image forming unit. Development by the developing devices 4Y, 4M, 4C, and 4K is performed by reversal development in which a development bias in which an AC voltage is superimposed on a DC voltage having the same polarity (negative polarity in this embodiment) as the polarity of the toner to be used is applied. . The intermediate transfer belt 6 is wound around a plurality of rollers and is rotatably supported. Each of the Y, M, C, and BK colors formed on each of the photosensitive drums 1Y, 1M, 1C, and 1K. A toner image is transferred.

  Here, an outline of the image forming process will be described below. Each color image formed by the image forming units 10 </ b> Y, 10 </ b> M, 10 </ b> C, and 10 </ b> K is subjected to primary transfer bias (not shown) having a polarity (positive polarity in this embodiment) opposite to the toner to be used. The rollers 7Y, 7M, 7C, and 7K are sequentially transferred (primary transfer) onto the rotating intermediate transfer belt 6 to form a synthesized color image (color image: color toner image). The color image is transferred from the intermediate transfer belt 6 to the paper P.

  The paper P accommodated in the paper cassettes 20A, 20B, and 20C is fed by the feed roller 21 and the paper feed roller 22A provided in the paper cassettes 20A, 20B, and 20C, respectively, and the transport rollers 22B, 22C, 22D, After passing through the registration roller 23 and the like, the sheet is conveyed to the secondary transfer roller 7A, and the color image is collectively transferred to one surface (front surface) on the paper P (secondary transfer).

  The paper P on which the color image has been transferred is fixed by the fixing device 17, is sandwiched between the paper discharge rollers 24, and is placed on a paper discharge tray 25 outside the apparatus. The transfer residual toner remaining on the peripheral surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K after the transfer is cleaned by the image forming body cleaning means 8Y, 8M, 8C, and 8K, and enters the next image forming cycle.

  At the time of double-sided image formation, the paper P formed on one side (front surface) and discharged from the fixing device 17 is branched off from the sheet discharge path by the branching unit 26, and constitutes a sheet feeding and conveying unit. After passing through the circulation sheet passing path 27A, the front and back are reversed by a reversing conveyance path 27B which is a refeed mechanism (ADU mechanism), passes through the refeed conveyance section 27C, and merges at the sheet feeding roller 22D. The reversely conveyed sheet P is conveyed again to the secondary transfer roller 7A through the registration roller 23, and a color image (color toner image) is collectively transferred onto the other side (back side) of the sheet P. The paper P on which the color image has been transferred is fixed by the fixing device 17, is sandwiched between the paper discharge rollers 24, and is placed on a paper discharge tray 25 outside the apparatus. On the other hand, after the color image is transferred to the paper P by the secondary transfer roller 7A, the residual toner is removed by the intermediate transfer belt cleaning means 8A from the intermediate transfer belt 6 that has separated the curvature of the paper P. A temperature sensor 11C is provided in the fixing device 17 so as to detect the fixing temperature.

The time of forming these images, 52.3~63.9kg / m ² (1000 sheets) as the paper P about thin and 64.0~81.4kg / m ² (1000 sheets) of approximately plain paper, 83 .0~130.0kg / m ² (1000 sheets) about cardboard and 150.0kg / m ² (1000 sheets) about super thick paper is used. The thickness of the paper P (paper thickness) is about 0.05 to 0.15 mm.

  Inside the apparatus main body 101, temperature sensors 11A and 11B constituting temperature detecting means are attached. The temperature sensor 11 </ b> A is an example of a first temperature detection unit, and is installed in the vicinity of the intermediate transfer belt 6. The temperature sensor 11A detects an in-machine temperature such as the temperature of the intermediate transfer belt 6 and outputs a temperature detection signal S1.

  The temperature sensor 11B is an example of a second temperature detection unit, and is installed, for example, in the vicinity of or in the image writing unit 3K for the BK color. Of course, the image writing units 3Y, 3M, and 3C for the other Y, M, and C colors may be similarly provided. The temperature sensor 11B detects the temperature in the image writing unit and outputs a temperature detection signal. Thermocouple structures, thermistor structures, and IC thermocouple structures are used for the temperature sensors 11A, 11B, and 11C.

  A color misregistration detection sensor 12 as an example of a detection unit is provided on the upstream side of the cleaning unit 8A and on the left side of the intermediate transfer belt 6, and the image forming units 10Y, 10M, and 10C described above. A position detection signal is generated by detecting the position of a color image (hereinafter referred to as a registration mark CR) including a reference color for color misregistration correction formed on the intermediate transfer belt 6 by 10K.

  The apparatus main body 101 is provided with a system control unit 15 as an example of a control unit, and adjusts the image writing start position of the laser beam to the photosensitive drums 1Y, 1M, 1C, and 1K when the color misregistration correction mode is executed. Made. For example, in the color misregistration correction mode, a registration mark CR for color misregistration correction is formed on the intermediate transfer belt 6, the passage timing of the registration mark CR is read, and the position (edge, center of gravity, etc.) of the reference color registration mark CR is read. The amount of misregistration of other color registration marks is calculated, and the image forming position at the time of color superposition is corrected based on the amount of misregistration. Here, the image forming position at the time of color superposition refers to toner images of Y color, M color, C color, BK color, etc., when an arbitrary color image based on color image data is reproduced on the intermediate transfer belt 6. Is the position to overlap. This image forming position is corrected by adjusting the image writing start position for the photosensitive drums 1Y, 1M, 1C, and 1K.

  The system control unit 15 executes the other correction modes related to the image forming process other than the color misregistration correction mode, and executes the color misregistration confirmation mode following the other correction modes, so that the image forming units 10Y, 10M, 10C and 10K are controlled so as to determine whether or not to execute the color misregistration correction mode based on the detection result of the color misregistration confirmation pattern detected by the color misregistration detection sensor 12.

  In this example, other correction modes related to the image forming process include a surface potential correction process, a maximum density correction process, and a gradation correction process as a process correction mode (operation). In the surface potential correction process, a correction operation is performed to keep the surface potential of the photosensitive drums 1Y, 1M, 1C, and 1K constant. In the maximum density correction process, a correction operation is performed to keep the maximum density constant in the developing devices 4Y, 4M, 4C, and 4K. In the gradation correction processing, the image processing means 70 performs a correction operation for keeping the gradation constant from highlight to maximum density. In the process correction operation, the photoreceptor surface potential correction, the maximum density correction, and the gradation correction are executed as one set. For example, the process correction operation is executed after the end of the print job when the accumulated number of prints reaches 1000 prints or when it reaches more than 1000 prints.

  In addition, the system control unit 15 controls the image forming units 10Y, 10M, 10C, and 10K so that the color misregistration confirmation mode is executed as a series of operations at the end of the other correction modes. The image forming units 10Y, 10M, 10C, and 10K are configured to form a color misregistration confirmation pattern based on a process correction process that corrects the density condition of the color image.

  For example, in the color misregistration confirmation mode, a color misregistration confirmation pattern for confirming whether or not to execute the above-described color misregistration correction mode is formed on the photosensitive drums 1Y, 1M, 1C, and 1K, and the intermediate transfer belt 6 is used. The color misregistration confirmation pattern transferred to the color misregistration is detected, and it is determined whether or not to execute the color misregistration correction mode based on the detection result of the color misregistration confirmation pattern.

  In this color misregistration confirmation mode, the preset permissible misregistration value is compared with the misregistration amount obtained from the detection result of the color misregistration confirmation pattern. If the color misregistration amount is within the allowable range, the color misregistration correction mode is set. If the process ends without executing and exceeds the allowable range, the color misregistration correction mode is executed after the color misregistration confirmation mode.

  In this example, when the width direction of the intermediate transfer belt 6 is the main scanning direction, the color image for color misregistration correction has a line segment parallel to the main scanning direction and a predetermined angle with respect to the main scanning direction (for example, 45 °). For example, a color image constitutes a “F” character. For the color misregistration confirmation pattern, a reference patch or the like formed in the process correction process is used.

  FIG. 2 is an image diagram showing a configuration example of the Y color image writing unit 3Y and its skew adjusting means 9Y. The Y-color image writing unit 3Y shown in FIG. 2 includes a semiconductor laser light source 31, a collimator lens 32, an auxiliary lens 33, a polygon mirror 34, a polygon motor 35, an f (θ) lens 36, and a CY1 lens for mirror surface imaging. 37, a drum surface imaging CY2 lens 38, a reflecting plate 39, a polygon motor drive substrate 45, and an LD drive substrate 46.

  The semiconductor laser light source 31 is connected to a Y-color LD drive substrate 46. Write data Wy from the image writing unit 3Y is supplied to the LD drive substrate 46. Write data Wy is PWM-modulated on the LD drive substrate 46, and a laser drive signal SLy having a predetermined pulse width after PWM modulation is output to the semiconductor laser light source 31. The semiconductor laser light source 31 generates laser light based on the Y color laser drive signal SLy. Laser light emitted from the semiconductor laser light source 31 is shaped into a predetermined beam light by the collimator lens 32, the auxiliary lens 33, and the CY1 lens 37.

  This light beam is deflected in the main scanning direction by the polygon mirror 34. For example, a polygon motor 35 is attached to the polygon mirror 34. A polygon driving substrate 45 is connected to the polygon motor 35. The Y polygon CLK is supplied to the polygon drive board 45 from the system controller 15 described above. The polygon drive board 45 rotates the polygon motor 35 at a predetermined rotation speed based on the Y polygon CLK. The beam light deflected by the polygon mirror 34 is imaged toward the photosensitive drum 1Y by the f (θ) lens 36 and the CY2 lens 38. By this operation, an electrostatic latent image such as a registration mark CR is formed on the photosensitive drum 1Y.

  The image writing unit 3Y is provided with skew adjusting means 9Y. The skew adjusting means 9Y is attached to the main body. A reflection plate 39 is provided in the main body, and a laser index sensor 49 is attached at a position facing the reflection plate 39. The laser index sensor 49 detects the light beam deflected by the polygon mirror 34 and outputs a Y-INDEX signal to the system control unit 15. The skew adjustment means 9Y has an adjustment gear unit 41 and an adjustment motor 42. A CY2 lens 38 is attached to the adjustment gear unit 41. The adjustment gear unit 41 is movably attached to the CY2 lens 38. The adjustment motor 42 moves and adjusts the adjustment gear unit 41 in the horizontal direction based on the skew adjustment signal SSy.

  In this example, the calculation of the color misregistration amount in the color misregistration correction mode is based on the registration mark CR of BK color. This is for adjusting the writing position of the Y, M, and C color images to match the BK color. There are, for example, the following five i to v in the color misregistration correction mode. Among the correction processing contents, i to iii are realized by correcting the image data, and iv and v drive the motor 42 and actually adjust by driving the image writing units 3Y, 3M, 3C, and 3K. To be made.

i. Main Scanning Correction Processing This processing is correction for aligning the writing position in the main scanning direction of Y, M, C, and BK color images. For example, regarding the Y color writing position correction, the position detection data Dp of the BK registration mark CR and the position shift amount of the Y color in the main scanning direction with respect to the Bk color from the position detection data Dp of the Y registration mark CR are calculated. The correction amount is calculated from the position shift amount obtained here. Based on this correction amount, the writing timing of the Y, M, and C colors in the main scanning direction is adjusted to align the Bk color with the writing positions of the other Y, M, and C colors. For example, the image writing position in the main scanning direction is adjusted by changing the start position of the main scanning effective signal.

ii. Sub-scanning correction processing This processing is correction for aligning the writing position in the sub-scanning direction of Y, M, C, and BK color images. For example, regarding the Y color writing position adjustment, the position detection data Dp of the BK registration mark CR and the positional deviation amount of the Y color in the sub-scanning direction with respect to the Bk color from the position detection data Dp of the Y registration mark CR are calculated. The correction amount is calculated from the position shift amount obtained here. Based on this correction amount, the writing timing of the Y, M, and C colors in the sub-scanning direction is adjusted to align the Bk color with the writing positions of the other Y, M, and C colors. For example, the image writing position in the sub-scanning direction is adjusted by changing the start position of the sub-scanning effective signal.

iii. Overall Horizontal Magnification Correction Processing This processing is correction for aligning the image forming positions in the entire Y, M, C, and BK color images. For example, the main scanning magnification is adjusted by changing the frequency of the image clock signal (main scanning clock signal), thereby adjusting the laser emission timing, and correcting the total lateral magnification deviation based on this adjustment. It is made like. The sub-scanning magnification is adjusted by changing the speed of the photoreceptors 1Y, 1M, 1C, 1K and the intermediate transfer belt 6.

iv. Partial lateral magnification correction processing This processing is correction for adjusting the inclination (bending) of the horizontal position of each of the image writing units 3Y, 3M, 3C, 3K, and the like. For example, one of the image writing units 3Y in the horizontal direction is fixed to the main body, and the other is movable, and a Y color correction unit 5Y shown in FIG. 2 rotates a motor (not shown) based on the position correction signal Sy. Then, the adjustment gear unit is driven to adjust the inclination of the image writing unit 3Y in the XY (horizontal) direction. This is for adjusting the inclination of the horizontal position of the writing unit 3Y with respect to the photosensitive drum 1Y. Similar processing is performed in the other image forming units 10M and 10C.

v. Skew Correction Processing This processing is correction for adjusting the inclination of the vertical position of the CY2 lens 38 in each of the image writing units 3Y, 3M, 3C, 3K. For example, one side of the CY2 lens 38 is supported and fixed to the image writing unit 3Y, and the other side is movable up and down. The Y-color skew adjusting means 9Y shown in FIG. The adjustment gear unit 41 is driven based on the adjustment signal SSy, and the CY2 lens 38 is moved and adjusted in the vertical direction. This is to adjust the inclination of the vertical position of the CY2 lens 38 with respect to the photosensitive drum 1Y. Similar processing is performed in the other image forming units 10M and 10C.

  FIG. 3 is a block diagram illustrating a configuration example of a control system of the color image forming apparatus 100. A color image forming apparatus 100 shown in FIG. 3 includes a system control unit 15, an operation panel 48, an image forming unit 60, and an image reading apparatus 102.

  The image reading apparatus 102 is connected to the system control unit 15 through a control line 81. The image reading device 102 is provided with an image reading unit 40, which reads an image from the original 30 shown in FIG. 1 and outputs digital image data Din to the system control unit 15 through a control line 81.

  The operation panel 48 is connected to the system control unit 15 through the control line 81 together with the image reading apparatus 102 described above. The operation panel 48 uses GUI (Graphic User Interface) type operation means. The operation panel 48 includes, for example, an input unit 16 configured with a touch panel and a display unit 18 configured with a liquid crystal display panel. The power switch is provided on the operation panel 48. The input unit 16 is connected to the CPU 57 through a control line 81, and is operated when selecting image forming conditions and the paper cassettes 20A to 20C. The image forming conditions, paper feed cassette selection information, and the like set by the input unit 16 are output to the CPU 57 as operation data D3. In addition to the input unit 16, the display unit 18 is connected to the CPU 57, and operates to display a menu selection screen (not shown), image forming conditions, and the like.

  The system control unit 15 includes an image memory 13, a nonvolatile memory 14, a correction amount calculation unit 51, a CPU (Central Processing Unit) 57, a ROM (Read Only Memory) 58, a work RAM (Random Access Memory) 59, an image A processing unit 70 and a system bus 82 are included. The system bus 82 is connected to the control lines 81 and 82 through an interface (not shown), and in the system control unit 15, the image memory 13, the nonvolatile memory 14, the correction amount calculation unit 51, the CPU 57, the ROM 58, the work RAM 59, and the image processing unit 70. Connected to.

  The image memory 13 stores the image data Din input from the image reading device 102. The non-volatile memory 14 records position detection data Dp after the A / D conversion and binarization of the position detection signal output from the color shift detection sensor 12 in the color shift correction mode. In addition to the position detection data Dp, the nonvolatile memory 14 stores data related to the positional shift amount ε and the color shift amount.

  The correction amount calculation unit 51 executes main scanning correction amount calculation processing, sub-scanning correction amount calculation processing, overall horizontal magnification correction amount calculation processing, partial horizontal magnification correction amount calculation processing, and skew correction amount calculation processing. For example, the correction amount calculation unit 51 reads the position detection data Dp from the nonvolatile memory 14 in the color misregistration correction mode, and shifts of error factors (main scanning, overall magnification, partial horizontal magnification, skew) from the position detection data Dp. An amount is calculated, and a correction amount for each error factor is obtained from the calculated shift amount.

  In the main scanning correction amount calculation process, the position detection data Dp is read from the non-volatile memory 14 to calculate the positional deviation amount in the main scanning direction, and the timing for adjusting the writing timing in the main scanning direction so as to eliminate this positional deviation amount. Control data D11 is generated. The timing control data D11 is used to correct the misalignment in the main scanning direction.

  In the sub-scanning correction amount calculation process, the position detection data Dp is read from the nonvolatile memory 14 to calculate the position deviation amount in the sub-scanning direction, and the timing for adjusting the writing timing in the sub-scanning direction so as to eliminate this position deviation amount. Control data D12 is generated. The position control in the sub-scanning direction is corrected by the timing control data D12.

  In the overall lateral magnification correction amount calculation process, the position detection data Dp is read from the nonvolatile memory 14 to calculate the overall lateral magnification displacement amount, and a clock for adjusting the frequency of the pixel clock signal so as to eliminate the overall lateral magnification displacement amount. Control data D13 is generated. With this clock control data D13, it is possible to correct the overall lateral double shift amount.

  In the partial lateral magnification correction amount calculation process, the position detection data Dp is read from the nonvolatile memory 14 to calculate the partial lateral magnification deviation amount, and the horizontal inclination of the image writing unit 3Y or the like is set so as to eliminate the partial lateral magnification deviation amount. Unit control data D14 for adjustment is generated. With this unit control data D14, the partial lateral magnification shift amount can be corrected.

  In the skew correction amount calculation process, the position detection data Dp is read from the nonvolatile memory 14 to calculate the skew displacement amount, and the skew control for adjusting the vertical inclination of the image writing unit 3Y or the like so as to eliminate this skew displacement amount. Data D15 is generated. The skew deviation amount can be corrected by the skew control data D15.

  The ROM 58 stores system program data for controlling the entire image forming apparatus. The work RAM 59 temporarily stores control commands when various modes are executed. When the power is turned on, the CPU 57 reads the system program data from the ROM 58, starts up the system, and controls the entire image forming apparatus. The CPU 57 adjusts the Y color, M color, and C color writing timing, the CLK frequency, the horizontal and vertical inclinations, and the like according to the correction amount of each error factor.

  The image processing means 70 performs image processing on the image data Din stored in the image memory 13 and transfers the image data Dout after the image processing to the image forming means 60. The image data Dout is sent to image writing units (exposure means) 3Y, 3M, 3C and 3K constituting the image forming means 60.

  In this example, the image forming unit 60 includes an apparatus internal temperature detection unit 61, a writing unit temperature detection unit 62, a fixing drive & temperature detection unit 63, a color shift detection unit 64, a color shift correction unit 65, a laser drive unit 66, and a drum drive. A unit 67, a process driving unit 68, and a paper conveying unit 69.

  The apparatus internal temperature detection unit 61 is connected to the temperature sensor 11A shown in FIG. 1 and A / D converts the temperature detection signal S1 to output temperature detection data D1 to the system control unit 15. The temperature detection data D1 is information indicating the in-machine temperature near the intermediate transfer belt.

  The writing unit temperature detection unit 62 is connected to the temperature sensor 11B shown in FIG. 1 and outputs temperature detection data D2 obtained by A / D converting the temperature detection signal to the system control unit 15. The temperature detection data D2 is information indicating the temperature in the BK color image writing unit 1K, for example.

  The fixing drive & temperature detection unit 63 is connected to the fixing device 17 shown in FIG. 1 and drives a heat source in the fixing device based on the fixing drive signal S11. The temperature sensor 11C provided in the fixing device measures the fixing temperature and outputs a temperature detection signal S41 to the fixing drive & temperature detection unit 63. The fixing drive & temperature detection unit 63 outputs to the system control unit 15 fixing temperature data D4 obtained by A / D converting the temperature detection signal S41.

  The color misregistration detection unit 64 is connected to the color misregistration detection sensor 12 shown in FIG. 1, A / D converts the position detection signal, and outputs the position detection data Dp to the system control unit 15. The position detection data Dp is information indicating the position of the registration mark CR formed on the intermediate transfer belt 6 by the above-described image forming units 10Y, 10M, 10C, and 10K. In the color misregistration confirmation mode, the color misregistration detection unit 64 receives a position detection signal obtained by detecting a color misregistration confirmation pattern from the color misregistration detection sensor 12, and A / D converts this signal to detect the position. Data Dp ′ is output to the system control unit 15.

  The color misregistration correction unit 65 constitutes a plurality of types of automatic correction means and is connected to the correction amount calculation unit 51. For example, timing control data D11 and D12, clock control data D13, unit control data D14, and skew control data D15 for stabilizing an image are input from the correction amount calculation unit 51 to the color misregistration correction unit 65.

  The color misregistration correction unit 65 operates so as to adjust the writing timing in the main scanning direction so as to eliminate the positional deviation amount in the main scanning direction based on the timing control data D11 generated based on the main scanning correction amount calculation processing. In addition, the color misregistration correction unit 65 operates to adjust the writing timing in the sub-scanning direction so as to eliminate the positional deviation amount in the sub-scanning direction, based on the timing control data D12 generated based on the sub-scanning correction amount calculation processing. To do.

  Further, the color misregistration correction unit 65 corrects the total lateral magnification deviation amount by the clock control data D13 generated based on the overall lateral magnification correction amount calculation processing. In addition, the color misregistration correction unit 65 corrects the partial lateral magnification deviation amount by the unit control data D14 generated based on the partial lateral magnification correction amount calculation processing. Further, the color misregistration correction unit 65 corrects the skew misregistration amount based on the skew control data D15 generated based on the skew correction amount calculation processing.

  The laser drive unit 66 is connected to the laser drive substrate 46 and supplies write data Wy to the LD drive substrate 46 through, for example, the Y-color image writing unit 3Y shown in FIG. 2 to control the output of the semiconductor laser light source 31. To do. The other M, C, and K color semiconductor laser light sources 31 are similarly controlled. Write data Wy and the like are supplied from the image processing means 70 to the laser driving unit 66.

  The drum driving unit 67 is connected to a motor (not shown) for rotating the photosensitive drums 1Y, 1M, 1C, 1K and the like, and controls the rotation of the motor based on the motor control signal S12. The motor control signal S12 is supplied from the system control unit 15 to the drum driving unit 67.

  The process driving unit 68 is connected to the charging units 2Y, 2M, 2C, and 2K and the developing devices 4Y, 4M, 4C, and 4K. For example, the process driving unit 68 applies a predetermined voltage to the charging unit 2Y based on the charging control signal S13, and operates so as to keep the surface potential of the photosensitive drum 1Y constant. The other charging means 2M, 2C, 2K and the like are similarly controlled. Further, the process driving unit 68 operates to apply a predetermined voltage to the developing device 4Y based on the development control signal S14 and to keep the maximum density of the toner member constant. The other developing devices 4M, 4C, 4K and the like are similarly controlled. The charging control signal S13 and the development control signal S14 are supplied from the system control unit 15 to the process driving unit 68.

  The paper transport unit 69 is connected to a motor (not shown) for driving the paper feed cassette, controls the rotation of the motor based on the paper feed control signal S15, and feeds the paper P fed from the paper feed cassette to the image forming system. Operate to transport. The paper feed control signal S15 is supplied from the system control unit 15 to the paper transport unit 69.

  FIG. 4 is a perspective view illustrating an example of registration mark CR detection by the two color misregistration detection sensors 12A and 12B. FIG. 5 is a diagram showing an example of forming a registration mark CR for color misregistration correction. The registration mark CR shown in FIG. 5 is formed when the color misregistration correction mode is executed. The image forming units 10Y, 10M, 10C, and 10K are controlled by the CPU 57 shown in FIG. 3 so that the registration marks CR for color misregistration are formed on the intermediate transfer belt 6.

  In this example, in the sub-scanning direction, which is the moving direction of the intermediate transfer belt 6, four BK-shaped registration marks CR for correcting color misregistration are formed in succession on the left and right ends. Subsequently, four C-color registration marks CR are formed continuously on the left and right ends, and four M-color registration marks CR are formed on the left and right ends. Subsequently, a Y-color registration mark CR is formed. Four marks CR are continuously formed on the left and right ends, respectively. The reason why the four registration marks CR of each color are formed at the left and right ends is to detect the image forming position of the registration mark CR of each color and correct it accurately.

  These color misregistration correction registration marks CR are detected by the color misregistration detection sensor 12, the color misregistration amount with respect to the image formation position of each color registration mark CR is calculated, and the Y, M, and C color image formation positions are corrected. . This correction is for accurately superimposing color images based on arbitrary image data in the image forming system after execution of the color misregistration correction mode.

6A and 6B are diagrams illustrating binarization examples of the position detection signal S2 by the color misregistration detection sensor 12A and the like.
In FIG. 6A, the position detection signal S2 obtained by the color misregistration detection sensor 12A or the like is binarized based on a preset threshold value Lth. In this example, the passing timing pulse signal Sp rises at the time ta when the point a at which the position detection signal S2 falls crosses the threshold value Lth, and the passing timing pulse at the time tb when the point b at which the position detection signal S2 rises crosses the threshold value Lth. The signal Sp falls. The passage timing pulse signal Sp is binarized and becomes position detection data Dp. The position detection data Dp is used to calculate the shift amount of the Y, M, and C color writing positions with respect to the writing position of the BK registration mark CR.

FIG. 7 is a diagram showing an example of the relationship between the registration mark CR for color misregistration correction and the color misregistration detection sensor 12.
The registration mark CR for color misregistration correction shown in FIG. 7 includes a line segment parallel to the main scanning direction and a line segment having an angle of θ = 45 ° with respect to the main scanning direction. In this example, an auxiliary line parallel to the sub-scanning direction is drawn from the center point c of the line segment parallel to the main scanning direction, and a point where this auxiliary line intersects with this 45 ° angle line segment. When d, the length of the line segment between the points cd is defined as Lb. In this example, the color misregistration detection of the registration mark CR for color misregistration correction is performed by calculating the length Lb of the line segment between the points cd from the detection time difference between the points c and d of the registration mark CR. The positional relationship in the main scanning direction with respect to the detection point of the sensor 12 can be detected.

  FIG. 8 is a diagram illustrating a calculation example of the color misregistration correction amount in the color misregistration correction mode. In this example, the color misregistration correction amount is calculated on the basis of the BK color registration mark CR in order to adjust the writing position of the Y, M, and C color registration marks CR to match the BK color registration mark CR. The For example, for the C color writing position adjustment, the writing position of the BK registration mark CR and the writing position of the C registration mark CR are detected, and the deviation amount of the C color writing position from the Bk color is calculated. The correction amount is obtained.

Here, T11 is the time when the color misregistration detection sensor 12A shown in FIG. 8 detects the linear portion in the main scanning direction of the BK registration mark CR at the left end, and the sensor 12A detects the inclined portion of the registration mark CR. Let the time be T12, the jumping distance from the detection locus line Lo of the sensor 12A to one end of the leftmost BK registration mark CR is A1, and the detection locus line Lo of the sensor 12A and the leftmost C registration mark CR. The main scanning coarse adjustment value [1] is expressed by the following equation (1), that is, when the jump distance to one end of A2 is A2.
[1] = A2-A1 = T12-T11 (1)
Is calculated by

Further, the time when the color misregistration detection sensor 12A detects the straight line portion in the main scanning direction of the left C registration mark CR is T13, and the left BK registration mark CR and the left C registration mark CR in the sub scanning direction. When the separation distance (reference value) B1 from the mark CR is set, the sub-scanning fine adjustment value [2] is an expression (2), that is,
[2] = 2240−B1 = 2240 (T13−T11) (2)
Is calculated by However, the numerical value “2240” is a design value of the separation distance between the Bk color and the C color. The actual distance varies depending on how to shift.

Further, the time when the color misregistration detection sensor 12A detects the inclined portion of the left C color registration mark CR is T14, and the color misregistration detection sensor 12B shown in FIG. The time when the linear portion in the scanning direction is detected is T21, the time when the sensor 12B detects the inclined portion of the registration mark CR is T22, and the straight line in the main scanning direction of the right C registration mark CR is detected by the sensor 12B. T23 is the time when the image is detected, and T24 is the time when the sensor 12B detects the inclined portion of the registration mark CR. The detection locus line Lo of the color misregistration detection sensor 12B and one end of the right BK registration mark CR The jumping distance to reach is A3, and the jumping distance to one end of the detection locus line Lo of the sensor 12B and the right side C-color registration mark CR is A. The separation distance (reference value) between the detection locus line Lo of the color misregistration detection sensor 12A and the detection locus line Lo of the color misregistration detection sensor 12B is C1, and the detection locus line Lo of the color misregistration detection sensor 12A and the color misregistration. When the separation distance (reference value) from the detection locus line Lo of the detection sensor 12B is C2, the overall lateral magnification adjustment value [3] in the main scanning direction is expressed by Equation (3), that is,
[3] = C2-C1
= (2360-A3 + A1)-(2360-A4 + A2)
= (A1-A3)-(A2-A4)
= [(T12-T11)-(T22-T21)]-[(T14-T13)-
(T24-T23)] (3)
Is calculated by However, the design value of the separation distance between the left and right BK registration marks CR is, for example, 2360 dots.

Further, the amount of misregistration (unknown) between the left BK registration mark CR and the right BK registration mark CR in the sub-scanning direction is D1, and the left C-color registration mark CR in the sub-scanning direction is When the amount of misalignment (unknown) between the C-color registration mark CR on the right side is D2, the skew adjustment value [4] is expressed by equation (4), that is,
[4] = D2-D1
= (T13-T23)-(T11-T21) (4)
Is calculated by

  Similarly, regarding the other M and Y color writing position adjustments, the amount of deviation between the writing position of the BK color registration mark CR and the writing position of the M or Y color registration mark CR is detected. Each correction amount is calculated from the amount. Thereafter, the C, M, and Y color image forming positions other than the BK color image forming unit 10K are adjusted.

  FIG. 9 is a diagram illustrating an example of formation of a color misregistration confirmation pattern PR by the color misregistration detection sensor 12B. The color misregistration confirmation pattern PR shown in FIG. 9 is formed when the color misregistration confirmation mode is executed. The image forming units 10Y, 10M, 10C, and 10K are controlled by the CPU 57 shown in FIG. 3 so that the color misregistration confirmation pattern PR is formed on the intermediate transfer belt 6.

  In this example, the color misregistration confirmation pattern PR includes a reference patch based on the C, M, and Y colors and a reference patch that combines the C, M, and Y colors. For example, in the color misregistration confirmation pattern PR, a Y-color reference patch is formed in a rectangular shape at the left end in the sub-scanning direction, which is the moving direction of the intermediate transfer belt 6. Subsequently, a green (hereinafter referred to as G color) reference patch is formed. The G reference patch is obtained by superimposing the Y color and the C color. The order of color superposition may be the case where the Y color is the lower layer and the C color is the upper layer, or vice versa.

  Further, a red (hereinafter referred to as “R”) reference patch is formed in succession to the G reference patch. The R reference patch is a superposition of the Y and M colors. The order of color superposition may be the case where the Y color is the lower layer and the M color is the upper layer, or the reverse order. A C reference patch is formed continuously with the R reference patch, a M reference patch is formed successively, and a BK reference patch is formed continuously.

  The reference patches for each color are formed with the writing positions aligned. The reason for aligning the writing position is to detect the image forming position of the pattern PR of each color and determine the necessity of the color misregistration correction mode at the present time. The color misregistration confirmation pattern PR is detected by the color misregistration detection sensor 12B, the color misregistration amount with respect to the image forming position of the reference patch of each color is calculated, and compared with a preset permissible misregistration value. The color misregistration detection sensor 12B outputs a position detection signal S2 to the color misregistration detection unit 64.

Next, the first image forming method according to the present invention will be described. FIG. 10 is a flowchart illustrating an example of color misregistration correction in the color image forming apparatus 100.
In this example, when the color misregistration correction time comes, and when correcting other than the color misregistration correction mode, the color misregistration confirmation mode is executed only for color misregistration confirmation, and the necessity of executing the color misregistration correction mode is determined. It is assumed that the color misregistration correction mode is executed in the image forming units 10Y, 10M, 10C, and 10K when it is determined that the color misregistration correction mode needs to be executed. In this example, it is assumed that the color misregistration correction time has arrived while the apparatus 100 is executing an image forming job. The process correction mode (operation) is executed when the total number of prints reaches 1000 prints or when it reaches more than that, and is executed after the print job ends. In addition, it is assumed that an allowable shift value applied in the color shift confirmation mode is set in advance.

  With this as a color misregistration correction condition, in step E1 of the flowchart shown in FIG. 10, the system control unit 15 determines whether the process correction execution condition is satisfied in step E1. The process correction execution condition includes an integrated value of the number of formed images from the time of the previous correction process to the present. For example, the counter in the system control unit 15 integrates the number of image formations from the time of the previous correction process to the present. This integrated value is detected by the CPU 57. For example, 1000 is set in advance as a reference value for the number of image formations in the CPU 57, and the CPU 57 monitors whether the number of image formations has reached the reference value = 1000.

  If the CPU 57 detects that the number of formed images has reached the reference value = 1000 and satisfies the process correction execution condition and determines that “the correction time has been reached”, step E2 is executed to execute the process correction. Then, the start-up operation in the image forming units 10Y, 10M, 10C, and 10K is executed.

  At this time, the process driving unit 68 outputs a charging control signal S13 to the charging units 2Y, 2M, 2C, and 2K. The charging unit 2Y applies a predetermined voltage to the photosensitive drum 1Y based on the charging control signal S13. The other charging means 2M, 2C, 2K, etc. are similarly controlled. In the developing device 4Y, a predetermined voltage is applied based on the development control signal S14. The other developing devices 4M, 4C, 4K and the like are similarly controlled.

  In step E3, the CPU 57 controls the image forming units 10Y, 10M, 10C, and 10K to execute a process correction operation. This process correction operation does not include a color misregistration correction mode, and the CPU 57 executes a process correction mode related to image forming processing other than the mode. In the process correction mode, surface potential correction processing, maximum density correction processing, and gradation correction processing are performed. In the surface potential correction process, a correction operation is performed to keep the surface potential of the photosensitive drums 1Y, 1M, 1C, 1K, etc. constant. In the maximum density correction process, a correction operation is performed to keep the maximum density constant in the developing devices 4Y, 4M, 4C, and 4K. In the gradation correction processing, the image processing means 70 performs a correction operation for keeping the gradation constant from highlight to maximum density. In the process correction mode, the photoreceptor surface potential correction, the maximum density correction, and the gradation correction are executed as one set.

  Thereafter, following the process correction mode described above, a color misregistration confirmation pattern PR is formed on the photosensitive drums 1Y, 1M1C, and 1K and transferred to the intermediate transfer belt 6 in step E4. The color misregistration confirmation pattern PR is a patch image or the like as shown in FIG. 9 for confirming whether or not to execute the color misregistration correction mode.

  In step E5, the color misregistration detection sensor 12 detects the color misregistration confirmation pattern PR transferred to the intermediate transfer belt 6. The color misregistration detection sensor 12 detects the position of the color misregistration confirmation pattern PR formed on the intermediate transfer belt 6 by the image forming units 10Y, 10M, 10C, and 10K, and generates a position detection signal S2. . The color misregistration detection sensor 12 outputs the position detection signal S2 to the color misregistration detection unit 64. The color misregistration detection unit 64 performs A / D conversion on the position detection signal S <b> 2 and outputs position detection data Dp ′ to the system control unit 15.

  Thereafter, the CPU 57 checks whether or not the color misregistration amount is within an allowable range in step E6 in order to determine whether or not to execute the color misregistration correction mode based on the detection result of the color misregistration confirmation pattern PR. If the color misregistration amount is within the allowable range, the process proceeds to step E8 without executing the color misregistration correction mode.

  If the color misregistration amount is outside the allowable range, the color misregistration correction mode is executed in step E7 following this color misregistration confirmation mode. At this time, as shown in FIGS. 4 and 5, registration marks CR of respective colors including a reference color for color misregistration correction are formed on the intermediate transfer belt 6. Then, as shown in FIG. 6, the passing timing of each color registration mark CR is read, and Y, M and C color registration marks for the BK registration mark CR as shown in FIGS. A CR misregistration amount is calculated, and an image forming position is corrected based on the misregistration amount.

  Thereafter, the process proceeds to step E8, and the falling operation in the image forming units 10Y, 10M, 10C, and 10K is executed. At this time, the process driving unit 68 outputs a charging control signal S13 to the charging units 2Y, 2M, 2C, and 2K, and outputs a developing control signal S14 to the developing devices 4Y, 4M, 4C, and 4K, and performs a falling operation. Execute. If the process correction execution condition is not satisfied in step E1 and the correction time has not been reached, the control is terminated without shifting to the correction process.

  As described above, according to the color image forming apparatus and the image forming method as the first embodiment of the present invention, when the color misregistration correction time comes, the system control unit 15 corrects the density condition of the color image. The color misregistration confirmation mode is executed after the correction mode. At this time, the system control unit 15 controls the image forming unit 60 to execute the color misregistration confirmation mode as a series of operations at the end of the process correction mode. The image forming unit 60 creates a color misregistration confirmation pattern PR based on the process correction mode. The system control unit 15 determines whether or not to execute the color misregistration correction mode based on the detection result of the color misregistration confirmation pattern PR detected by the color misregistration detection sensor 12.

  Therefore, since it is possible to determine whether or not the color misregistration correction mode is necessary before the execution of the color misregistration correction mode, it is possible to avoid a situation where the color misregistration correction mode is forcibly shifted to the color misregistration correction mode. be able to. In addition, the startup and shutdown operations in the process correction mode can be used together, and the startup process dedicated to the color misregistration correction mode and the shutdown process thereof need not be executed. As a result, the number of executions (frequency) of the color misregistration correction mode can be greatly reduced, and the operation time related to the correction processing can be greatly shortened. In addition, the toner member is not wasted. In addition, the accuracy in execution determination can be improved.

FIG. 11 is a block diagram illustrating a configuration example of the image transfer system I and the image forming system II of the color image forming apparatus 200 according to the second embodiment.
The second embodiment includes a system control unit 15 that controls the image forming units 10Y, 10M, 10C, and 10K when an arbitrary color image is formed on the intermediate transfer belt 6, and performs color misregistration based on temperature detection information. In addition to determining whether or not to correct, the image forming position in the image forming units 10Y, 10M, 10C, and 10K is corrected based on the color misregistration estimation correction mode. The color misregistration correction mode is executed only once for the first time, and the correction value and temperature at the time of executing the color misregistration correction mode are stored. Thereafter, the correction value acquired in advance is not executed without executing the color misregistration correction mode. In addition to being able to correct color misregistration by data processing, the operation time related to the correction processing can be greatly shortened.

  A color image forming apparatus 200 shown in FIG. 11 forms color toner images on the photosensitive drums 1Y, 1M, 1C, and 1K whose image forming positions are defined in advance, and transfers the color toner images to the intermediate transfer belt 6. An apparatus that superimposes colors and forms a color image. A processing system including the temperature sensors 11A, 11B, and 11C and the color misregistration detection sensor 12 shown in FIG. 1 is an image transfer system I, and the image forming units 10Y and 10M. , 10C, 10K are extracted as the image forming system II. The color image forming apparatus 200 operates to correct the color misregistration based on the color misregistration estimation correction mode.

  Here, the color misregistration estimation correction mode compares the temperature detection result in the machine at the start of warm-up with a predetermined temperature, and the first is when the temperature detection result is equal to or lower than the predetermined temperature. The color misregistration correction mode is executed, the first temperature detection result and the first correction value at the time of execution of the first color misregistration correction mode are acquired, and the color is obtained with respect to the first temperature detection result acquired here. When the temperature at which the deviation error is outside the allowable range is further detected, and the temperature at which the deviation error is outside the allowable range is detected, the second color registration correction mode is executed, and the second color registration correction mode is executed. The temperature detection result of 2 and the second correction value are acquired, and thereafter, the position of the other color image with respect to the reference color image using the first and second temperature detection results and the first and second correction values. Estimate the amount of deviation and correct the image forming position based on the estimated amount of positional deviation. It refers to the work.

  11, the color image forming apparatus 100 includes an image forming unit 10Y, 10M, 10C, 10K, a temperature sensor 11A, a nonvolatile memory 14, a system control unit 15, an input unit 16, a display unit 18, an apparatus internal temperature detection unit 61, A writing unit temperature detector 62 and an image processing means 70 are provided.

  An input unit 16 and a display unit 18 are connected to the system control unit 15, and operation data D3 such as image forming conditions is input by the user in a normal print mode. The input unit 16 is provided with a power switch (not shown). For example, power-on information is generated by pressing the power switch of the device 200 in the sleeping state. The power-on information becomes operation data D3 and is output from the input unit 16 to the system control unit 15.

  A temperature sensor 11A shown in FIG. 11 detects an in-machine temperature such as the temperature of the intermediate transfer belt 6 and outputs a temperature detection signal S1. The temperature sensor 11 </ b> A is connected to the apparatus internal temperature detection unit 61. The apparatus internal temperature detection unit 61 is configured to output temperature detection data Dtp obtained by A / D converting the temperature detection signal S1 to the system control unit 15.

  In this example, the image writing unit 3Y is provided with a temperature sensor 11y, which detects the temperature in the unit and outputs a temperature detection signal S2y. The image writing unit 3M is provided with a temperature sensor 11m, which detects the temperature in the unit and outputs a temperature detection signal S2m. The image writing unit 3C is provided with a temperature sensor 11c, which detects the temperature in the unit and outputs a temperature detection signal S2c. The image writing unit 3K is provided with a temperature sensor 11K (= 11B), which detects the temperature in the unit and outputs a temperature detection signal S2k.

  Each temperature sensor 11y, 11m, 11c, 11k is connected to a writing unit temperature detection unit 62, and temperature detection data (temperature detection information) Dty obtained by A / D converting the temperature detection signals S2y, S2m, S2c, S2k, respectively. , Dtm, Dtc, and Dtk are output to the system control unit 15.

  A temperature sensor 11C provided in the fixing device measures the fixing temperature and outputs a temperature detection signal S41. The temperature sensor 11C is connected to the fixing drive & temperature detection unit 63. The fixing drive & temperature detection unit 63 outputs fixing temperature data D4 obtained by A / D converting the temperature detection signal S41 to the system control unit 15. The system control unit 15 compares the temperature detection result at the start of warm-up with a predetermined reference temperature set in advance. Based on this comparison result, the color misregistration correction mode is executed. The system control unit 15 executes the first color misregistration correction mode when the temperature detection result in the apparatus at the start of warm-up is equal to or lower than a preset reference temperature.

  In the color misregistration correction mode, the system control unit 15 operates to correct the image forming positions in the image forming units 10Y, 10M, 10C, and 10K. When the color misregistration correction mode is executed, the position detection signal S2 is output from the color misregistration detection sensor 12 to the system control unit 15. For details, refer to the first embodiment.

  In this example, both temperature detection in the image writing units 3Y, 3M, 3C, 3K and the like and temperature detection inside the apparatus such as in the vicinity of the intermediate transfer belt are executed. In this case, temperature detection in the image writing units 3Y, 3M, 3C, 3K, etc. is performed when the temperature rises by 5 ° C. in the color misregistration correction mode. The temperature inside the apparatus such as the vicinity of the intermediate transfer belt is detected when the temperature rises 7 ° C. in the color misregistration correction mode. As described above, the execution temperature condition that is the relationship between the temperature detection and the execution condition is appropriately determined based on the temperature increase ΔT that causes the color misregistration to be outside the allowable range.

  In this example, the system control unit 15 detects the temperature detection data Dtp output from the device internal temperature detection unit 61 and the temperature detection data Dty, Dtm, Dtc, Dtk output from the writing unit temperature detection unit 62 when the temperature rises. In addition, it is determined whether or not to correct the color misregistration based on the temperature detection data D4 output from the fixing drive & temperature detection unit 63, and the image forming units 10Y, 10M, 10C, and 10K based on the color misregistration estimation correction mode. The image forming position at is corrected.

  For example, when the power is turned on, the system control unit 15 compares the fixing temperature with a predetermined reference temperature set in advance, and executes the first color misregistration correction mode when the fixing temperature is equal to or lower than the reference temperature. In this example, the detected temperature inside the apparatus when the color misregistration correction mode is executed is (A), and the correction value when the first color misregistration correction mode is executed is (B). As described in the first embodiment, the correction value (B) is obtained through the calculation process of FIG.

  A nonvolatile memory 14 is further connected to the system control unit 15, and a data table for reference when executing the color misregistration estimation correction mode is constructed. The data table associates the temperature detection data D (A) acquired at the time of executing the first color misregistration correction mode with the correction value (B) and the temperature detection data acquired at the time of executing the second color misregistration correction mode. D (A) ′ and the correction value (B) ′ are related to each other. In addition to the above-described data table being built, the nonvolatile memory 14 stores position detection data Dp and data relating to the amount of positional deviation and the amount of color deviation.

  For example, the system control unit 15 detects whether or not the idling state of the device exceeds a predetermined time, and executes the first color misregistration correction mode when the idling state exceeds the predetermined time, thereby correcting the color misregistration. The temperature detection result D (A) and correction value (B) when the mode is executed are stored in the nonvolatile memory 14 as the first value. The system control unit 15 deletes the temperature detection result D (A) and the correction value (B) already stored in the nonvolatile memory 14 at the start of warm-up, and then enters the first color misregistration correction mode. Control for execution is started (reset operation).

  In this example, the temperature detection results obtained when the first color misregistration correction mode is obtained from the temperature sensors 11A, 11C, 11y, 11m, 11c, and 11k are stored in the nonvolatile memory 14, and each set predetermined temperature threshold is set. And the respective temperature detection results stored in the nonvolatile memory 14 are compared, and when a temperature exceeding the temperature threshold is detected, the second color misregistration correction mode is executed.

For example, the system control unit 15 determines whether there is a temperature rise exceeding a predetermined temperature threshold. As a discrimination criterion at this time, when the temperature detection data at the time t is D (t) and the temperature detection data including the temperature rise ΔT is D (A + ΔT), the equation (1), that is,
D (t)> D (A + ΔT) (1)
A temperature relational expression is defined.

  When this temperature relational expression D (t)> D (A + ΔT) is not satisfied, that is, when D (t) ≦ D (A + ΔT), the temperature inside the apparatus at the time t is continuously monitored. When the temperature relational expression D (t)> D (A + ΔT) is satisfied, the system control unit 15 executes the second color misregistration correction mode.

  The system control unit 15 further detects an in-machine temperature at which the color misregistration error is outside the allowable range with respect to the maximum value of the in-machine temperature at the time of execution of the first color misregistration correction mode updated and stored in the nonvolatile memory 14, and the allowable range When an outside temperature inside the apparatus is detected, the second color misregistration correction mode is executed, and the temperature detection result and the correction value when the second color misregistration correction mode is executed are stored in the nonvolatile memory 14 as the second value. Thereafter, all temperature detection results and correction values stored in the nonvolatile memory 14 are used to estimate the position shift amount of the other color image with respect to the reference color image, and image formation is performed based on the position shift estimated amount. The image forming positions in the units 10Y, 10M, 10C, and 10K are corrected.

  For example, when the system controller 15 executes the color misregistration estimation correction mode, the temperature detection data D (t) at the time t and the temperature detection data D (A) ′ when the second color misregistration correction mode is executed. And the correction value (B) obtained when the first color misregistration correction mode is executed or the correction value (B) ′ obtained when the second color misregistration correction mode is executed is set. Decide what to do.

As a determination criterion at this time, when the temperature detection data at the time t is D (t) and the temperature detection data at the time of executing the second color misregistration correction mode is D (A) ′, D (t) <D (A) 'is determined. In this example,
If D (t) <D (A) ′, use the correction value (B),
When D (t) ≧ D (A) ′, the correction value (B) ′ is used.

The correction value at the time of execution of the color misregistration estimation correction mode may be calculated by introducing the ratio expression shown in Expression (2).
Correction value = (D (t−A) / D (A′−A)) × (B′−B) + B (2)
However, when the value of D (t−A) becomes negative, D (t−A) = 0.

  In this way, the color misregistration amount can be estimated and corrected from the temperature detection result without executing a new correction operation. The system control unit 15 refers to the data table when executing the color misregistration estimation correction mode, and the photosensitive drums 1Y, 1M, and Dc of the image data Dy, Dm, and Dc based on the correction amount obtained by referring to the data table. The timing for writing to 1C is adjusted.

  The system control unit 15 executes the first color misregistration correction mode when the power-on information is detected again and the fixing temperature is equal to or lower than a predetermined reference temperature. In this case, the nonvolatile memory 14, the detected temperature (A) and the correction value (B) are updated, and the detected temperature (A) ′ and the correction value (B) ′ are deleted.

  The image processing means 70 includes an image processing circuit 71, a Y-signal switching unit 72Y, an M-signal switching unit 72M, a C-signal switching unit 72C, and a K-signal switching unit 72K. The image processing circuit 71 includes R, G, B signals related to R, G, B color components of a color image read from an arbitrary document, and Y, M related to an arbitrary print output from an external device such as a printer. , C, K signals are input.

  In the image processing circuit 71, the R, G, B signals are color-converted based on the image processing control signal S4, and the image data Dy is output to the Y-signal switching unit 72Y. Similarly, the R, G, B signals are color-converted and the image data Dm is output to the M-signal switching unit 72M. The R, G, B signals are color-converted and the image data Dc is converted to the C-signal switching unit 72C. The R, G, B signals are color-converted and the image data Dk is output to the K-signal switching unit 72K.

  In this example, when Y, M, C, K signals relating to arbitrary printing are input to the image processing circuit 71 from an external printer or the like, the Y signal is subjected to, for example, screen processing based on the image processing control signal S4. Is output to the Y-signal switching unit 72Y. Similarly, the image data Dm ′ after screen processing of the M signal is output to the M-signal switching unit 72M, and the image data Dc ′ after screen processing of the C signal is output to the C-signal switching unit 72C. The image data Dk ′ after the screen processing of the K signal is output to the K-signal switching unit 72K. The image processing control signal S4 is output from the system control unit 15 to the image processing circuit 71.

  The Y-signal switching unit 72Y selects either the image data Dy or the image data Dy 'based on the write selection signal S5, and outputs the image data Dy or Dy' to the image writing unit 3Y. The M-signal switching unit 72M selects either the image data Dm or the image data Dm ′ based on the write selection signal S5, and outputs the image data Dm or Dm ′ to the image writing unit 3M.

  The C-signal switching unit 72C selects either the image data Dc or the image data Dc 'based on the write selection signal S5, and outputs the image data Dc or Dc' to the image writing unit 3C. The K-signal switching unit 72K selects either the image data Dk or the image data Dk ′ based on the write selection signal S5, and outputs the image data Dk or Dk ′ to the image writing unit 3K. The write selection signal S5 is output from the system control unit 15 to each of the Y to K-signal switching units 72Y to 72K.

  In this example, a Y color image writing unit (exposure means) 3Y is provided with a correcting means 5Y, and writing in the main scanning direction of the photosensitive drum 1Y is performed based on a writing position correction signal Sy from the system control unit 15. The position is adjusted. Similarly, a correction unit 5M is attached to the M color image writing unit 3M, and the writing position of the photosensitive drum 1M in the main scanning direction is adjusted based on a writing position correction signal Sm from the system control unit 15. To be made. The C-color image writing unit 3C is provided with a correcting means 5C, which adjusts the writing position of the photosensitive drum 1C in the main scanning direction based on the writing position correction signal Sc from the system control unit 15. The

  In this example, the calculation of the color misregistration amount in the color misregistration correction mode is based on the registration mark CR1 of BK color. This is for adjusting the writing position of the Y, M, and C color images to match the BK color. For example, regarding the Y color writing position adjustment, the writing position of the BK color registration mark CR and the writing position of the Y color registration mark CR are detected, and the writing position of the Y color registration mark CR and the BK color registration position are detected. The amount of correction is calculated from the amount of deviation from the writing position of the mark CR. Similarly, with regard to the M and C color writing position adjustment, a deviation amount between the writing position of the BK color registration mark CR and the writing position of the M or C color registration mark CR is detected, and from this deviation amount. Each correction amount is calculated. Thereafter, the Y, M, and C color image forming positions are adjusted.

  Next, the second image forming method according to the present invention will be described. 12 and 13 are flowcharts showing examples of color misregistration correction (parts 1 and 2) in the color image forming apparatus 200. FIG.

  In this example, the power-on information is detected, the in-machine temperature at the time of temperature rise is detected, and it is determined whether or not to correct the color shift based on the detected in-machine temperature detection result. It is assumed that the image forming position is corrected based on the shift estimation correction mode. As for temperature detection information, a case where temperature detection data Dtp and D4 obtained from the temperature sensor 11A and the temperature sensor 11C are used is taken as an example.

  Using these as color misregistration correction conditions, the system control unit 15 detects power-on information in step F1 of the flowchart shown in FIG. The power-on information is generated, for example, when the user or the like presses the power switch of the input unit 16 of the device 200 in the sleeping state. The power-on information is output from the input unit 16 to the system control unit 15.

  Thereafter, in step F2, the system control unit 15 inputs the temperature detection data D4 through the fixing drive & temperature detection unit 63, and reads the fixing temperature in the fixing device 17 shown in FIG.

  In step F3, the system control unit 15 detects whether or not the fixing temperature exceeds a predetermined reference temperature set in advance, and determines whether or not the fixing temperature is equal to or lower than the reference temperature. When the fixing temperature is equal to or lower than the reference temperature, the system control unit 15 proceeds to step F4 and executes the first color misregistration correction mode (operation). The correction value (B) obtained in this color misregistration correction mode is set (set) in the correction means 5Y, 5M, 5C, etc. through the color misregistration correction unit 65 shown in FIG. As described in the first embodiment, the correction value (B) is obtained through the calculation process of FIG.

  In step F5, the system control unit 15 further reads the temperature detection data Dtp through the apparatus internal temperature detection unit 61 and also reads the temperature detection data D4 through the fixing drive & temperature detection unit 63. Thereafter, in step F6, the system control unit 15 initializes the nonvolatile memory 14. The detected temperature obtained from the temperature detection data Dtp and the temperature detection data D4 at this time is displayed as (A). In step F <b> 7, the system control unit 15 stores the detected temperature (A) and the correction value (B) in the nonvolatile memory 14. This is for use in the color misregistration estimation correction mode for correcting the subsequent image forming position.

  If the fixing temperature exceeds the reference temperature in step F3 described above, the process proceeds to step F8, and temperature detection data D (t) at the time t is read. The temperature detection data D (t) includes temperature detection data Dtp and temperature detection data D4. Of course, temperature detection data D2y, D2m, D2c, and D2k by the temperature sensors 11y, 11m, 11c, and 11k may be included.

  Next, in step F9, the system control unit 15 determines whether there is a temperature rise. As a discrimination criterion at this time, when the temperature detection data at the time t is D (t) and the temperature detection data including the temperature rise ΔT is D (A + ΔT), D (t)> D (A + ΔT) A temperature relational expression is defined. When this temperature relational expression D (t)> D (A + ΔT) is not satisfied, that is, when D (t) ≦ D (A + ΔT), the process returns to step F8 to continue monitoring the in-machine temperature at the time t. To be made.

  When the temperature relational expression D (t)> D (A + ΔT) is satisfied in Step F9, the system control unit 15 proceeds to Step F10 in the flowchart shown in FIG. 13 and executes the second color misregistration correction mode. The correction value (B) ′ obtained in the color misregistration correction mode is set in the correction means 5Y, 5M, 5C, etc. through the color misregistration correction unit 65 shown in FIG. The correction value (B) ′ is obtained through the calculation process of FIG. 8 as described in the first embodiment.

  Thereafter, the process proceeds to step F11, and the system control unit 15 further reads the temperature detection data D (t) at the time. The detected temperature obtained from the temperature detection data Dtp and the temperature detection data D4 at this time is displayed as (A) '. In step F <b> 12, the system control unit 15 stores the detected temperature (A) ′ and the correction value (B) ′ in the nonvolatile memory 14. This is for use in subsequent color misregistration estimation correction modes.

  Thereafter, the process proceeds to step F13, and the system control unit 15 further reads the temperature detection data D (t) at the time t in order to execute the color misregistration estimation correction mode. Next, in step F14, the system control unit 15 compares the temperature detection data D (t) at the time t with the temperature detection data D (A) ′ at the time of executing the second color misregistration correction mode. It is determined whether to set the correction value (B) obtained when the first color misregistration correction mode is executed or the correction value (B) ′ obtained when the second color misregistration correction mode is executed. As a discrimination criterion at this time, when the temperature detection data at the time t is D (t) and the temperature detection data at the time of executing the second color misregistration correction mode is D (A) ′, D (t) < A temperature magnitude determination formula D (A) ′ is defined.

  When the temperature detection data D (t) at the time t satisfies D (t) <D (A) ′ in step F14, the process proceeds to step F15 and the correction value (B) is corrected to the correction means 5Y, 5M, 5C, etc. To be set to Thereafter, the process proceeds to step F17. When the temperature detection data D (t) at the time t does not satisfy D (t) <D (A) ′, that is, when D (t) ≧ D (A) ′, the process proceeds to step F16. The correction value (B) ′ is set in the correction means 5Y, 5M, 5C, etc. (color misregistration estimation correction mode).

  Thereafter, the process proceeds to step F17, and the system control unit 15 determines the end. For example, the system control unit 15 detects power-off information and shifts to a sleeping state. The power off information is generated by turning off the power switch of the input unit 16 of the device 200. If the power-off information is not detected, the process returns to step F13 to repeat the above-described processing.

  As described above, according to the color image forming apparatus and the image forming method as the second embodiment of the present invention, the system control unit 15 is configured to form an arbitrary color image on the intermediate transfer belt 6 in an overlapping manner. The first color misregistration correction mode is executed when the temperature detection result in the machine at the start of warm-up is equal to or lower than a predetermined reference temperature set in advance. The image forming units 10Y, 10M, 10C, and 10K form color images on the photosensitive drums 1Y, 1M, 1C, and 1K based on the first color misregistration correction mode.

  The system controller 15 updates the in-machine temperature D (A + ΔT) at which the color misregistration error is outside the allowable range with respect to the maximum value of the in-machine temperature D (A) when the first color misregistration correction mode is updated and stored in the nonvolatile memory 14. ) Is further detected, and the in-machine temperature D (A + ΔT) that is outside the allowable range is detected, the second color misregistration correction mode is executed, and the temperature detection result D (2) when the second color misregistration correction mode is executed. A) 'and the correction value (B)' are stored in the nonvolatile memory 14, and thereafter, all the temperature detection results (A) (A) 'stored in the nonvolatile memory 14 and the correction values (B), (B)'. Are used to estimate the positional deviation amount of the other color image with respect to the reference color image, and the image forming positions in the image forming units 10Y, 10M, 10C, and 10K are corrected based on the estimated positional deviation amount. .

  Accordingly, when the temperature inside the machine rises, the second color misregistration correction mode is executed only once for the first time after exceeding the allowable temperature, and the machine temperature (A) ′ and the correction value (B) ′ when the color misregistration correction mode is executed. Thereafter, the in-machine temperature (A), (A) ′ and the correction values (B), (B) ′ acquired in advance without executing any of the first and second color misregistration correction modes are stored. Therefore, the color misregistration can be corrected by data processing, so that the number of execution times of the color misregistration correction mode can be greatly reduced, and the toner member is not wasted.

  In this embodiment, the temperature inside the fixing device 17 and the vicinity of the intermediate transfer belt is monitored, and the color misregistration correction mode is executed corresponding to the temperature detection result obtained from each temperature sensor 11A and 11C. As described above, the color misregistration correction mode may be executed corresponding to the temperature detection result obtained from the temperature sensors 11y, 11m, 11C, and 11k (11B) in the image writing units 3Y, 3M, 3C, and 3K. . It is possible to make a correction execution determination with higher accuracy.

  In each embodiment, with respect to the image forming units 10Y, 10M, 10C, and 10K, image forming units that form toner images of Y, M, C, and BK colors on the photosensitive drums 1Y, 1M, 1C, and 1K. The case of having 10Y, 10M, 10C, and 10K and the image transfer belt 6 that transfers the toner images formed on the photosensitive drums 1Y, 1M, 1C, and 1K for the respective colors has been described. In other words, the present invention can also be applied to a color image forming apparatus that forms a color image by superimposing colors on one transfer material conveying belt.

  The present invention is extremely suitable when applied to a tandem type color printer or copying machine having an intermediate transfer belt or a transfer material conveying belt, a complex machine of these, and the like.

1 is a conceptual diagram illustrating a configuration example of a color image forming apparatus 100 as each embodiment of the present invention. It is an image figure which shows the structural example of the image writing unit 3Y for Y color, and its skew adjustment means 9Y. 2 is a block diagram illustrating a configuration example of a control system of the color image forming apparatus 100. FIG. It is a perspective view which shows the example of detection of the registration mark CR by two color misregistration detection sensors 12A and 12B. It is a figure which shows the example of formation of the registration mark CR for color misregistration correction. (A) And (B) is a figure which shows the binarization example of position detection signal S2 by 12 A of color misregistration detection sensors. 6 is a diagram illustrating an example of a relationship between a registration mark CR for color misregistration correction and a color misregistration detection sensor 12. FIG. It is a figure which shows the example of calculation of the color shift correction amount in the color shift correction mode. It is a figure which shows the example of formation of the pattern PR for the color misregistration confirmation by the color misregistration detection sensor 12B. 5 is a flowchart illustrating an example of color misregistration correction in the color image forming apparatus 100. FIG. 6 is a block diagram illustrating a configuration example of an image transfer system I and an image forming system II of a color image forming apparatus 200 according to a second embodiment. 5 is a flowchart illustrating an example (part 1) of color misregistration correction in the color image forming apparatus 200. 5 is a flowchart illustrating an example (part 2) of color misregistration correction in the color image forming apparatus 200.

Explanation of symbols

1Y, 1M, 1C, 1K Photosensitive drum (image forming body)
3Y, 3M, 3C, 3K Image writing unit (image forming means)
4Y, 4M, 4C, 4K Developing device 5Y, 5M, 5C Correction means 6 Intermediate transfer member (image forming member)
10Y, 10M, 10C, 10K Image forming unit (image forming means)
11A, 11B, 11C, 11y, 11m, 11c, 11k Temperature sensor (temperature detection means)
12, 12A, 12B Color shift detection sensor (detection means)
14 Nonvolatile memory 15 System control unit (control means)
16 Input section
DESCRIPTION OF SYMBOLS 17 Fixing device 18 Display part 48 Operation panel 100 Color image forming apparatus 101 Main body 102 Image reading apparatus 201 Automatic document feeder 202 Document image scanning exposure apparatus

Claims (13)

In a color image forming apparatus for forming an arbitrary color image on an image forming body,
An image of each color including a reference color for color misregistration correction is formed on the image forming body, the passing timing of the image for color misregistration correction is read, and the amount of misregistration of another color image with respect to the reference color image is calculated. The operation for correcting the image forming position based on the amount of misregistration is a color misregistration correction mode,
Forming an image for color misregistration confirmation for confirming whether or not to execute the color misregistration correction mode on the image forming body, detecting an image for color misregistration confirmation formed on the image forming body, When the operation for determining whether or not to execute the color misregistration correction mode based on the detection result of the image for color misregistration confirmation is the color misregistration confirmation mode,
An image forming unit having the image forming body and forming a color image on the image forming body;
Detecting means for detecting a color image formed by the image forming means;
The image forming unit is controlled to execute another correction mode related to the image forming process other than the color misregistration correction mode, and to execute the color misregistration confirmation mode following the other correction mode. A color image forming apparatus comprising: control means for determining whether or not to execute the color misregistration correction mode based on the detected result of the color misregistration confirmation image. The control means includes
The color image forming apparatus according to claim 1, wherein the image forming unit is controlled to execute a color misregistration confirmation mode as a series of operations at the end of the other correction mode. The image forming unit includes:
The color image forming apparatus according to claim 1, wherein the color misregistration confirmation image is generated based on a process correction process for correcting a density condition of the color image. Other correction modes related to the image forming process include
The color image forming apparatus according to claim 1, further comprising a surface potential correction process, a maximum density correction process, and a gradation correction process of the image forming body. In a color image forming apparatus for forming an arbitrary color image on an image forming body,
An image of each color including a reference color for color misregistration correction is formed on the image forming body, the passing timing of the image for color misregistration correction is read, and the amount of misregistration of another color image with respect to the reference color image is calculated. The operation for correcting the image forming position based on the amount of misregistration is a color misregistration correction mode,
Comparing the temperature detection result in the machine at the start of warm-up with a predetermined temperature set in advance, if the temperature detection result is below a predetermined temperature, the first color misregistration correction mode is executed,
Obtaining a first temperature detection result and a first correction value when executing the first color misregistration correction mode;
If the temperature at which the color misregistration error is outside the allowable range is further detected with respect to the acquired first temperature detection result, and the temperature at which the color misregistration error is outside the allowable range is detected, the second color misregistration correction mode is detected. Run
A second temperature detection result and a second correction value at the time of executing the second color misregistration correction mode are acquired, and thereafter, the first and second temperature detection results and the first and second correction values are obtained. When using the color misregistration estimation correction mode to estimate the position shift amount of the other color image with respect to the reference color image and correct the image forming position based on the position shift estimated amount,
An image forming unit having the image forming body and forming a color image on the image forming body;
Temperature detecting means for detecting temperature inside the machine and outputting temperature detection information;
Control for determining whether to correct the color misregistration based on the temperature detection information output by the temperature detecting means, and correcting the image forming position in the image forming means based on the color misregistration estimation correction mode A color image forming apparatus comprising: means. The control means includes
6. The color image formation according to claim 5, wherein the first color misregistration correction mode is executed when a temperature detection result in the apparatus at the start of the warm-up is equal to or lower than a predetermined temperature set in advance. apparatus. The control means includes
Detecting whether the idling state of the device exceeds a predetermined time,
When the idling state exceeds a predetermined time, the first color misregistration correction mode is executed,
6. The color image forming apparatus according to claim 5, wherein a temperature detection result and a correction value at the time of executing the first color misregistration correction mode are stored in a memory as a first value, and the stored contents are sequentially updated. . The control means includes
An internal temperature at which the color misregistration error is outside the allowable range with respect to the maximum value of the internal temperature at the time of execution of the first color misregistration correction mode updated and stored in the memory is further detected, and the internal temperature outside the allowable range When the second color misregistration correction mode is executed,
The temperature detection result and correction value at the time of executing the second color misregistration correction mode are stored in the memory as a second value, and thereafter, all the temperature detection results and correction values stored in the memory are used. The color image formation according to claim 7, wherein a positional deviation amount of another color image with respect to the reference color image is estimated, and an image forming position in the image forming unit is corrected based on the positional deviation estimation amount. apparatus. The control means includes
The temperature detection result and the correction value that are already stored in the memory are deleted at the start of the warm-up, and then control for executing the first color misregistration correction mode is started. Item 9. The color image forming apparatus according to Item 5 to 8. The image forming means includes a writing unit and an intermediate transfer member,
The temperature detecting means includes
A first temperature detecting means for detecting the temperature of the intermediate transfer member; and a second temperature detecting means for detecting the temperature of the writing unit;
6. The color image forming apparatus according to claim 5, wherein a color misregistration correction mode is executed in accordance with a temperature detection result obtained from each of the first and second temperature detecting means. Storing each temperature detection result at the time of execution of the first color misregistration correction mode obtained from the first and second temperature detection means in the memory;
Comparing each set predetermined temperature threshold value with each temperature detection result stored in the memory, and executing a second color misregistration correction mode when a temperature exceeding the temperature threshold value is detected. The color image forming apparatus according to claim 10. The first temperature detection means is installed in the vicinity of the intermediate transfer member,
The color image forming apparatus according to claim 10, wherein the second temperature detection unit is installed in the vicinity of the writing unit or in the writing unit. In an image forming method for forming an arbitrary color image on an image forming body,
An image of each color including a reference color for color misregistration correction is formed on the image forming body, the passing timing of the image for color misregistration correction is read, and the amount of misregistration of another color image with respect to the reference color image is calculated. The operation for correcting the image forming position based on the amount of misregistration is a color misregistration correction mode,
Comparing the temperature detection result in the machine at the start of warm-up with a predetermined temperature set in advance, if the temperature detection result is below a predetermined temperature, the first color misregistration correction mode is executed,
Obtaining a first temperature detection result and a first correction value when executing the first color misregistration correction mode;
If the temperature at which the color misregistration error is outside the allowable range is further detected with respect to the acquired first temperature detection result, and the temperature at which the color misregistration error is outside the allowable range is detected, the second color misregistration correction mode is detected. Run
A second temperature detection result and a second correction value at the time of executing the second color misregistration correction mode are acquired, and thereafter, the first and second temperature detection results and the first and second correction values are obtained. When using the color misregistration estimation correction mode to estimate the position shift amount of the other color image with respect to the reference color image and correct the image forming position based on the position shift estimated amount,
Detecting the temperature inside the machine,
An image forming method comprising: determining whether to correct color misregistration based on the detected detection result of the in-machine temperature; and correcting the image forming position based on the color misregistration estimation correction mode.

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