Color image forming apparatus, color image forming method, color image forming program and recording medium

The present invention relates to a color image forming apparatus, a color image forming method, a color image forming program, and a recording medium.

Generally, a color image forming apparatus has an image forming means and an environmental state detecting means for detecting an environmental state including temperature and humidity in the vicinity of the image forming means. In this device, when the detected value of the environmental state including the temperature and humidity of the environmental state detecting means exceeds a predetermined value in the middle of continuously forming a plurality of images, and when the detected value exceeds the predetermined value. When a predetermined number of images are not formed and a predetermined number of images are formed, a predetermined pattern image is formed by the alignment pattern image forming means between the images, and the formed predetermined pattern image is used as the pattern reading means. The image is read and the alignment is controlled by the control means (see, for example, Patent Document 1). The image forming process of the image forming apparatus (color image forming apparatus) using the above-mentioned prior art is as follows.

FIG. 8 shows the configuration of a color image forming apparatus called a tandem type in which image forming portions are arranged along a transport belt. This device is a direct transfer type device that does not use an intermediate transfer body. Four image forming parts, each forming an image of a different color (magenta: M, cyan: C, yellow: Y, black: K), are arranged in a row along a transport belt 2 for transporting the transfer paper 1 as recording paper. Have been placed. The transport belt 2 is erected by a drive roller 3 that is driven and rotated and a driven roller 4 that is driven and rotated, and is rotationally driven in the direction of an arrow by the rotation of the conveyor roller 3. A paper feed tray 5 in which the transfer paper 1 is stored is provided in the lower part of the transport belt 2. The transfer paper at the uppermost position of the stored transfer paper 1 is fed at the time of image formation and is adsorbed on the transport belt 2 by electrostatic adsorption.

The adsorbed transfer paper 1 is conveyed to a first image forming unit (magenta), where magenta image forming is performed. The first image forming unit (magenta) is composed of a photoconductor drum 6M, a charger 7M arranged around the photoconductor drum 6M, an exposure device 8, a developer 9M, and a photoconductor cleaner 10M. The surface of the photoconductor drum 6M is uniformly charged by the charger 7M and then exposed by the exposure device 8 with the laser beam 11M corresponding to the magenta image to form an electrostatic latent image. The laser beam 11M is emitted from a laser light source 5 equipped with an LD (laser diode) corresponding to each color of magenta, cyan, and yellow. The formed electrostatic latent image is developed by the developing device 9M, and a toner image is formed on the photoconductor drum 6M. This toner image is transferred by the transfer device 12M at a position (transfer position) where the photoconductor drum 6M and the transfer paper 1 on the transport belt 2 are in contact with each other, and a single color (magenta) image is formed on the transfer paper 1.

In the photoconductor drum 6M after transfer, unnecessary toner remaining on the drum surface is cleaned by the photoconductor cleaner 10M to prepare for the next image formation. In this way, the transfer paper 1 to which the single color (magenta) is transferred by the first image forming portion (magenta) is conveyed to the second image forming portion (cyan) by the conveying belt 2. Also in this second image forming portion, the toner image (cyan) formed on the photoconductor drum 6C is transferred on the transfer paper 1 in the same manner as described above. The transfer paper 1 is further conveyed to a third image forming unit (yellow) and a fourth image forming unit (black), and the similarly formed toner image is transferred to form a color image. The transfer paper 1 on which the color image is formed after passing through the fourth image forming portion is peeled off from the transport belt 2, fixed by the fixing device 13, and then discharged from the color image forming apparatus.

Further, above the transport belt 2 of the main body of the color image forming apparatus, detection sensors 14, 15 and 16 for detecting the pattern of the mark row for detecting misalignment are attached. Reference numeral 100 denotes a paper feed roller, and the central shaft is connected to an output shaft of a drive motor (not shown) via an electromagnetic clutch 110 (see FIG. 2) described later. Reference numeral 101 denotes a pair of resist rollers, the central axis of one of the rollers is connected to the output shaft of the drive motor, and the pair of resist rollers 101 are arranged in a substantially close contact state. The transfer paper 1 is separately fed by the paper feed roller 100 and the resist roller pair 101.

FIG. 9 shows a part of the position shift detection toner mark row 17 formed on the transport belt 2 shown in the color image forming apparatus of FIG. FIG. 10 is a diagram showing position fluctuations due to driving of the transport belt shown in the color image forming apparatus of FIG. 8, where the horizontal axis is the time axis and the vertical axis is the fluctuation amount axis. A set of marks consisting of four horizontal lines (lines in the direction orthogonal to the transport direction of the transport belt) and four diagonal lines of each color K, Y, C, and M shown in Fig. 9 is used as one set. Eight sets Mark rows 17 are formed along the transport direction. Each of the eight sets of mark rows 17 is adjusted to the position fluctuation phase caused by the drive speed fluctuation such as belt running in the sub-scanning direction (arrow 90 direction), and as shown in FIG. 10, the error in pattern formation and detection is as small as possible. It is formed in consideration of the phase so as to reduce the number. By determining the correction amount from the result of calculating the average of these detection results, it is possible to form a high-quality image with little misalignment of each color.

Eight sets of K, Y, C, and M horizontal and diagonal lines are formed, respectively, and by detecting with sensors 14, 15, and 16 arranged in the main scanning direction, skew and sub-scanning with respect to the reference color (BK in this case) are performed. It is possible to measure resist misalignment, main scanning resist misalignment, and main scanning magnification error. By shifting the image in the direction opposite to the misalignment direction by 1/2 of the maximum misalignment amount detected by each sensor, It is possible to correct the amount of deviation due to the magnification deviation in the main scanning direction so as not to be noticeable. Various deviation amounts, correction amounts are calculated, and correction execution commands are executed by the main CPU. The detected pattern is cleaned by the cleaning means 18. Such misalignment correction was executed according to an instruction from the user menu, service menu, or printer driver of the device (the timing of this misalignment correction is set to timing B, and the misalignment correction automatically performed by the color image forming apparatus side). Let the timing be timing A. For example, refer to Patent Document 2).<patcit num="1"><text>Japanese Patent No. 3540402</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 2003-186278</text></patcit>

<p> However, in the above-mentioned conventional technique, in order to increase productivity during continuous printing, the distance between the recording papers is made as small as possible. Therefore, when it becomes necessary to correct the misalignment, the execution timing B is used. Since it is not possible to form a pattern in which the total length of the pattern is long and the pattern must be detected with a short pattern length, the detection accuracy is lowered and the image is deteriorated due to the misalignment. Therefore, an object of the present invention is to provide a color image forming apparatus, a color image forming method, a color image forming program, and a recording medium capable of accurately correcting misalignment even during continuous printing.</p>

<p> In order to solve the above problems, the invention according to claim 1 is a plurality of inventions that are arranged along the transport direction of the recording paper and develop a latent image formed on the photoconductor by exposure to form an unfixed color image. An unfixed color image forming unit, a transfer means for transferring the unfixed color image to the intermediate transfer body and then retransferring to the recording paper, or a transfer means for directly transferring the unfixed color image to the recording paper, and the above. A color image forming apparatus including a transporting means for transporting recording paper to the transfer means, in which the transport interval between the recording papers is made wider than a predetermined interval, and the transporting means or the intermediate transfer body is widened. It is characterized in that at least one row of mark rows is formed in the area, and a correction means for detecting the mark rows and performing misalignment correction during continuous printing is provided. According to the invention of claim 1, the apparatus is stopped by making the transport interval between the recording sheets wider than a predetermined interval and forming at least one row of mark rows in the widened area of the transport means or the intermediate transfer body. You don't have to. By detecting the mark rows formed in the area between the recording sheets, it is possible to cancel the influence of the speed fluctuation in the transport direction of the transport means or the intermediate transfer material (by averaging the detection results of the mark rows). , The accuracy of misalignment correction can be improved.</p><p> The invention according to claim 2 includes a plurality of unfixed color image forming portions arranged along the transport direction of the recording paper and developing a latent image formed on the photoconductor by exposure to form an unfixed color image. A transfer means for transferring the unfixed color image to the intermediate transfer body and then retransferring it to the recording paper, or a transfer means for directly transferring the unfixed color image to the recording paper, and the recording paper to the transfer means. A color image forming apparatus including a transporting means for transporting, in which the transporting interval between the recording sheets is made wider than a predetermined interval, and at least one row of mark rows is provided in the widened region of the transporting means or the intermediate transfer body. Is formed, the mark string is detected and the misalignment correction is performed during continuous printing, and when the misalignment correction is automatically performed, the length is shorter than the length of the mark string used when the correction is performed according to the instruction from the user. It is characterized by using a mark sequence of length. According to the invention of claim 2, since the alignment mark length formed between the papers can be shortened as much as possible, the decrease in productivity can be minimized.</p><p> The invention according to claim 3 is the invention according to claim 1 or 2, wherein the correction means makes the transfer interval between the recording sheets wider than the interval during normal printing and narrower than the outer peripheral length of the photoconductor. Based on the interval adjusting means, the mark row forming means for forming the mark row in the widened region of the transporting means or the intermediate transfer body, the alignment sensor for detecting the mark row, and the output from the sensor. It is characterized in that it is provided with a control means for correcting the misalignment of the unfixed color image during continuous printing by performing the calculation. According to the invention of claim 3, the transfer interval between the recording sheets is made wider than the interval during normal printing and narrower than the outer peripheral length of the photoconductor to correct the misalignment. The length along the line can be set to a length that can detect the misalignment with high accuracy, and the image quality of the recording paper can be improved.</p><p> The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the transport means transfers the unfixed image to each of the unfixed color image forming portions of the recording paper. It is characterized in that it is provided with a loop-shaped transport belt for transporting the transport belt and a rotary drive means for rotationally driving the transport belt.</p><p> The invention according to claim 5 is the invention according to any one of claims 1 to 3, wherein the unfixed image and the mark string from each of the unfixed color image forming portions are transferred to the intermediate transfer body. It is characterized by including a loop-shaped transfer belt and a rotation driving means for rotationally driving the transfer belt.</p><p> The invention according to claim 6 is the invention according to any one of claims 1 to 3, wherein the unfixed color image and the mark string from each of the unfixed color image forming portions are transferred to the intermediate transfer body. A transfer drum and a rotating means for rotating the transfer drum are provided.</p><p> The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the mark row forming means forms an unfixed pattern of the mark row between forming the unfixed image. The control means also serves as the unfixed color image forming unit, and the control means delays the timing of forming the unfixed color image in order to form the mark sequence in the unfixed color image forming unit, and also delays the timing of forming the unfixed color image. The transfer interval adjusting means delays the transfer timing of the recording paper by the length of the mark row in the transfer direction.</p><p> The invention according to claim 8 is the invention according to any one of claims 1 to 7, wherein the length of the mark row along the transport direction of the recording paper can detect the misalignment with high accuracy. It is characterized by being as long as possible. According to the invention of claim 8, the length of the mark row along the transport direction of the recording paper is a length that can detect the misalignment with high accuracy. Therefore, (the average of the detection results of the mark row). It is possible to cancel the influence of the transporting means or the transporting direction of the intermediate transfer body (by taking), and it is possible to improve the accuracy of the misalignment correction.</p><p> The invention according to claim 9 is the invention according to any one of claims 1 to 8, wherein the correction means automatically corrects each predetermined number of prints, or is instructed by a user. It is characterized by making corrections from time to time. According to the invention of claim 9, maintenance is facilitated when the correction is automatically performed for each predetermined number of prints, and when the correction is made when instructed by the user, the transport system is used. It can be adjusted when replacing parts, and high image quality can be maintained.</p><p> The invention according to claim 10 is the invention according to any one of claims 1 to 9, wherein the mark sequence has all the image-forming colors. According to the invention of claim 10, since the mark sequence consisting of all the image-forming colors is formed in one area, the number of times to widen the interval between the recording sheets is only once, and the productivity (number of prints). The decrease in the number of sheets can be suppressed to the minimum of 1 or less.</p><p> The invention according to claim 11 is the invention according to any one of claims 1 to 9, wherein the mark sequence forms two unfixed color images having the farthest positional relationship among the unfixed color image forming portions. It is characterized by having the color of the part. According to the invention of claim 11, since the mark row has the colors of the two unfixed color image forming portions having the farthest positional relationship among the unfixed color image forming portions, (the average of the detection results of the mark row). It is possible to cancel the influence of the speed fluctuation in the transport direction of the transport means or the intermediate transfer plate (by taking), it becomes easier to detect the misalignment, and the consumption of toner required for image formation is suppressed as much as possible. Can be done.</p><p> The invention according to claim 12 is the invention according to any one of claims 1 to 9, wherein the mark sequence is a combination of two unfixed color image forming portions having the largest misalignment among combinations of unfixed color images. It is characterized by having a color. According to the invention of claim 12, since the mark sequence has the colors of the two unfixed color image forming portions having the largest misalignment among the combinations of the unfixed color images, it is easy to grasp the detection of the misalignment. At the same time, the amount of toner consumed for image formation can be suppressed as much as possible.</p><p> The invention according to claim 13 is the invention according to any one of claims 10 to 12, at least one of a main scanning resist component, a main scanning magnification component, a sub-scanning resist component, and a skew component according to the mark string. It is characterized by detecting a component. According to the invention of claim 13, at least one of the main scanning resist component, the main scanning magnification component, the sub-scanning resist component, and the skew component is detected by the mark sequence, and therefore, it is a detection target between recording sheets. A pattern in which the deviation component can be detected can be formed, and high image quality can be achieved.</p><p> The invention according to claim 14 is characterized in that, in the invention according to claim 13, only the main scanning magnification component is detected by the mark string. According to the invention of claim 14, since only the main scanning magnification component is detected by the mark sequence, the arithmetic processing can be saved, the misalignment can be corrected quickly, and the decrease in productivity can be minimized. ..</p><p> The invention according to claim 15 is characterized in that, in the invention according to claim 13, only the sub-scanning resist component is detected by the mark string. According to the invention of claim 15, since only the sub-scanning resist component is detected by the mark sequence, the arithmetic processing can be saved and the decrease in productivity can be minimized.</p><p> The invention according to claim 16 is characterized in that, in the invention according to claim 13, a main scanning resist component, a main scanning magnification component, and a sub-scanning resist component are detected by the mark string. According to the invention of claim 16, since the main scanning resist component, the main scanning magnification component, and the sub-scanning resist component are detected by the mark sequence, there is no detection of the skew component which is hardly present in reality, and the calculation process is performed accordingly. Labor saving can be achieved.</p><p> The invention according to claim 17 is characterized in that, in the invention according to claim 13, the pattern of the mark sequence includes a line shape perpendicular to the transport direction of the recording paper. According to the invention of claim 17, since the mark row pattern includes a line shape perpendicular to the transport direction of the recording paper, at least a deviation component in the sub-scanning direction can be detected, and high image quality can be achieved. Can be done.</p><p> The invention according to claim 18 is the invention according to claim 13, wherein the detection sensor for detecting the mark string includes an optical element and utilizes a change in the amount of specularly reflected light or transmitted light. The pattern is characterized by including an oblique line shape having a predetermined angle in the transport direction of the recording paper. According to the invention of claim 18, the detection sensor for detecting the mark row includes an optical element and utilizes a change in the amount of specularly reflected light or transmitted light, and the pattern of the mark row is in the transport direction of the recording paper. Since the oblique line shape having a predetermined angle is included, at least the deviation in the main scanning direction can be detected, and the image quality can be improved.</p><p> The invention according to claim 19 is the invention according to claim 13, wherein the detection sensor for detecting the mark sequence includes an optical element and utilizes a change in the amount of diffused light, and the pattern of the mark sequence is recorded. It is characterized by including a line shape parallel to or orthogonal to the paper conveying direction. According to the invention of claim 19, the detection sensor for detecting the mark sequence includes an optical element and utilizes a change in the amount of diffused light, and the pattern of the mark sequence has a line shape parallel to the transport direction of the recording paper. Therefore, at least the deviation in the main scanning direction can be detected, and the image quality can be improved.</p><p> According to the invention of claim 20, a latent image is formed on a photoconductor by exposure, the latent image is developed to form an unfixed color image on a recording paper, and a mark string for unfixed alignment is formed on the recording paper. This is a color image forming method for correcting the misalignment of the unfixed color image by forming it on the transport means or the intermediate transfer body, detecting the amount of misalignment of the mark string, and calculating the amount, and is an output from the sensor. Based on the above, the transport interval between the recording sheets is made wider than a predetermined interval, and a plurality of mark rows are formed in the widened region of the transport means or the intermediate transfer body in the transport direction, and the mark rows are detected. The feature is that the misalignment correction is performed during continuous printing. According to the invention of claim 20, the apparatus is stopped by making the transport interval between the recording sheets wider than a predetermined interval and forming at least one row of mark rows in the widened area of the transport means or the intermediate transfer body. You don't have to. By detecting the mark rows formed in the area between the recording sheets, it is possible to cancel the influence of the speed fluctuation in the transport direction of the transport means or the intermediate transfer material (by averaging the detection results of the mark rows). , The accuracy of misalignment correction can be improved.</p><p> According to the invention of claim 21, a latent image is formed on a photoconductor by exposure, the latent image is developed to form an unfixed color image on a recording paper, and a mark string for unfixed alignment is formed on the recording paper. This is a color image forming method for correcting the misalignment of the unfixed color image by forming it on the transport means or the intermediate transfer body, detecting the amount of misalignment of the mark string, and calculating the amount, and is an output from the sensor. Based on the above, the transport interval between the recording sheets is made wider than the normal print interval, and a plurality of mark rows are formed in the widened region of the transport means or the intermediate transfer body in the transport direction, and the mark rows are formed. When detecting and performing misalignment correction during continuous printing and automatically performing misalignment correction, use a mark string with a length shorter than the length of the mark string used when correcting according to the instruction from the user. It is characterized by. According to the invention of claim 21, since the alignment mark length formed between the papers can be shortened as much as possible, the decrease in productivity can be minimized.</p><p> The invention according to claim 22 is an intermediate step A of developing an latent image formed on a photoconductor by exposure to form an unfixed color image and the unfixed color image in a control means of a color image forming apparatus. Step B of transferring to the transfer body and then retransferring to the recording paper, or transferring the unfixed color image directly to the recording paper, procedure C of transporting the recording paper to the transfer means, between the recording papers. Procedure D in which the transport interval is made wider than a predetermined interval to form at least one row of mark rows in the widened area of the transport means or the intermediate transfer body, and the mark rows are detected to correct the misalignment during continuous printing. It is characterized in that the procedure E to be performed is executed. According to the invention of claim 22, the apparatus is stopped by making the transport interval between the recording sheets wider than a predetermined interval and forming at least one row of mark rows in the widened area of the transport means or the intermediate transfer body. You don't have to. By detecting the mark rows formed in the area between the recording sheets, it is possible to cancel the influence of the speed fluctuation in the transport direction of the transport means or the intermediate transfer material (by averaging the detection results of the mark rows). , The accuracy of misalignment correction can be improved.</p><p> The invention according to claim 23 is an intermediate step A of developing an latent image formed on a photoconductor by exposure to form an unfixed color image and the unfixed color image in a control means of a color image forming apparatus. Step B of transferring to the transfer body and then retransferring to the recording paper, or transferring the unfixed color image directly to the recording paper, procedure C of transporting the recording paper to the transfer means, between the recording papers. Procedure D in which the transport interval is made wider than a predetermined interval to form at least one row of mark rows in the widened area of the transport means or the intermediate transfer body, and the mark rows are detected to correct the misalignment during continuous printing. At the same time, when the misalignment correction is automatically performed, the procedure F is executed using a mark string having a length shorter than the length of the mark string used when the correction is performed according to an instruction from the user. According to the invention of claim 23, since the alignment mark length formed between the papers can be shortened as much as possible, the decrease in productivity can be minimized.</p><p> The invention according to claim 24 is an intermediate step A of developing an latent image formed on a photoconductor by exposure to form an unfixed color image and the unfixed color image in a control means of a color image forming apparatus. Step B of transferring to the transfer body and then retransferring to the recording paper, or transferring the unfixed color image directly to the recording paper, procedure C of transporting the recording paper to the transfer means, between the recording papers. Procedure D in which the transport interval is made wider than a predetermined interval to form at least one row of mark rows in the widened area of the transport means or the intermediate transfer body, and the mark rows are detected to correct the misalignment during continuous printing. It is characterized in that the program to execute the procedure E to be performed is recorded. According to the invention of claim 24, the apparatus is stopped by making the transport interval between the recording sheets wider than a predetermined interval and forming at least one row of mark rows in the widened area of the transport means or the intermediate transfer body. You don't have to. By detecting the mark rows formed in the area between the recording sheets, it is possible to cancel the influence of the speed fluctuation in the transport direction of the transport means or the intermediate transfer material (by averaging the detection results of the mark rows). , The accuracy of misalignment correction can be improved.</p><p> The invention according to claim 25 is an intermediate step A of developing an latent image formed on a photoconductor by exposure to form an unfixed color image and the unfixed color image in a control means of a color image forming apparatus. Step B of transferring to the transfer body and then retransferring to the recording paper, or transferring the unfixed color image directly to the recording paper, procedure C of transporting the recording paper to the transfer means, between the recording papers. Procedure D in which the transport interval is made wider than a predetermined interval to form at least one row of mark rows in the widened area of the transport means or the intermediate transfer body, and the mark rows are detected to correct the misalignment during continuous printing. In addition to performing this, when automatically correcting the misalignment, it is characterized by recording a program that executes step F using a mark string with a length shorter than the length of the mark string used when correcting according to the instruction from the user. And. According to the invention of claim 25, since the alignment mark length formed between the papers can be shortened as much as possible, the decrease in productivity can be minimized.</p>

<p> By making the transport interval between the recording sheets wider than the predetermined interval and forming at least one row of mark rows in the widened area of the transport means or the intermediate transfer body, it is not necessary to stop the apparatus. By detecting the mark rows formed in the area between the recording sheets, it is possible to cancel the influence of the speed fluctuation in the transport direction of the transport means or the intermediate transfer material (by averaging the detection results of the mark rows). Since the accuracy of misalignment correction can be improved, it is possible to provide a color image forming apparatus, a color image forming method, a color image forming program, and a recording medium capable of performing misalignment correction with high accuracy even during continuous printing. be able to.</p>

FIG. 1 is a flowchart showing an embodiment of the color image forming method of the present invention, and FIG. 2 is a block diagram showing an embodiment of a color image forming apparatus to which the color image forming method of the present invention is applied. In FIG. 2, the CPU 26, RAM 27, ROM 28, and I / O port 24 are connected by bus lines 25 and 29. A rotation control board 33 that controls the motor 32 that rotationally drives the drive roller 3 (see FIG. 2) is connected to the I / O port 24, a write control board 31 that drives the laser light source 5 is connected, and a clutch drive circuit. 34 is connected, and further, a light emitting amount control unit 30, a FIFO (First In First Out memory) 23, and a sampling control unit 22 are connected. The CPU 26 has a function of controlling the color image forming apparatus in an integrated manner, and for example, a microcomputer is used.

Image data is input to the write control board 31, and control signals are input from the I / O (input / output port) 24. Based on these image data and control signals, each unfixed color image forming unit forms an unfixed color image. The sensors 14 (15, 16) connected to the light emitting amount control unit 30 are composed of a light emitting unit (for example, a light emitting diode) and a light receiving unit (for example, a phototransistor). The light emitting amount control unit 30 has a function of controlling the light emitting amount of the light emitting unit. The light receiving part of the sensor 14 (15, 16) is connected to the amplifier AMP19, and the filter 20, the A / D (analog / digital converter) 21 and the FIFO 23 are connected to the amplifier AMP19. The output of the sampling control unit 22 is connected to the A / D 21.

Next, the function of each member of the color image forming apparatus shown in FIG. 2 will be described. The sensor 14 (15, 16) transmits the reflected light of the light applied to the misalignment detection toner mark row (position misalignment detection mark row or mark row) 17 formed on the transport belt (or transfer belt, etc.) 2. Convert to an electrical signal. At least one misalignment detection sensor 14 (15, 16) in the main body of the color image forming apparatus in a direction (main scanning direction) orthogonal to the transport direction of the transport belt 2 (or intermediate transfer body) as a transport body. Is provided, the amount of misalignment of the mark for detecting misalignment is detected, calculated, and the position of the unfixed color image is corrected.

Here, as the arithmetic processing, for example, the arithmetic processing described in JP-A-11-65208, JP-A-2002-160398, and JP-A-2002-207337 is used. The signal obtained by the sensor 14 (15, 16) is amplified by the amplifier AMP 19, and the frequency component above the frequency (for example, several hundred Hz) required by the filter (low-pass filter) 20 is cut. The signal is converted from analog data to digital data by A / D21. Data sampling is controlled by the sampling control unit 22 (in this embodiment, the sampling rate is, for example, 100 KHz). The sampled data is sequentially stored in the FIFO memory 23. Here, only the configuration of one sensor 14 is shown, but since the same configuration is used for the other sensors 15 and 16, they are omitted. After the detection of the pattern of the misalignment detection mark string 17 is completed, the data stored in the ROM 28 is loaded into the CPU 26 and RAM 27 by the data bus line 25 via the I / O port 24, and various types are loaded by the CPU 26. Arithmetic processing for calculating the amount of deviation and arithmetic processing for optimizing the image formation conditions are performed.

On the other hand, various programs are stored in the ROM 28, including a program for calculating various deviation amounts and a program for performing arithmetic processing for optimizing image formation conditions. The ROM address, RAM address, and various input / output devices are specified by the address bus line 29. In addition, the CPU 26 monitors the detection signal from the detection sensor 14 (15, 16) at an appropriate timing, causing deterioration of the light emitting part of the transport belt 2 (see FIG. 8) and the sensor 14 (15, 16). However, the amount of light emitted is controlled by the light emitting amount control unit 30 so that the detection can be performed reliably, and the level of the received signal from the light receiving unit is controlled to be always constant. The CPU 26 is applied to the write control board 31 in order to change each frequency based on the correction amount obtained from the detection result of the pattern of the misalignment detection mark string 17 and the change of the main and sub resists, the skew correction and the magnification error. On the other hand, make the setting. On the write control board 31, a device that can set the output frequency very finely, for example, VCO (voltage controlled) A clock generator using oscillator) is provided for each color including the standard color. This output is used as an image clock.

(Embodiments of Claims 1, 3 to 15) The embodiments of claims 1, 3 to 15 are characterized in that misalignment is detected with high accuracy even during continuous printing. First, each photoconductor drum 6M, 6C, 6Y, 6K is charged by the chargers 7M, 7C, 7Y, 7K while rotating in the direction of the arrow, and each charged photoconductor drum 6M, 6C, 6Y, 6K is charged with a laser light source 5 Latent images are formed on each photoconductor drum 6M, 6C, 6Y, 6K by exposure from, and each latent image is developed by each developer 9M, 9C, 9Y, 9K to form an unfixed color image, respectively. Each unfixed color image is sequentially transferred by the transfer devices 12M, 12C, 12Y, and 12K so as to overlap one sheet of transfer paper 1, and when it is transferred to the fixing device 13 by the transport belt 2, the unfixed color is transferred by the fixing device 13. When the image is fixed, a color image is formed on the transfer paper 1. When the unfixed color image is transferred from each photoconductor drum 6M, 6C, 6Y, 6K to the transfer paper 1, excess toner is added to each photoconductor drum 6M, 6C, 6Y by the photoconductor cleaners 10M, 10C, 10Y, 10K. , Removed from 6K, the next latent image is formed. The above is the normal operation of color image formation.

Here, the transfer paper 1 is conveyed by the transfer belt 2 as the transfer body (in the case of the intermediate transfer type, the intermediate transfer body is provided, and the unfixed color images of each color are superimposed on the intermediate transfer body and then on the transfer paper. Batch transfer).

Next, the formation and detection of the misalignment detection mark row 17 (see FIG. 9) will be described. When the misalignment detection mark row 17 is formed in the transport direction of the transport belt 2, it is necessary to widen the interval (between papers) of the transfer paper 1 by the length of the misalignment detection mark row 17 in the transport direction. The formation, detection, and misalignment correction of the misalignment detection mark row 17 are performed every time a predetermined number of prints (for example, 5000) of color images are formed, or when a user replaces a part or the like. Since it is performed according to the instruction, when the misalignment correction instruction is input to the CPU 26, the CPU 26 waits for the transfer of the transfer paper 1 on the transfer belt 2 by the length of the misalignment detection mark row 17 and the transfer paper. While waiting for 1, a latent image of the misalignment detection mark row 17 is formed on each of the photoconductor drums 6M, 6C, 6Y, and 6K. The misalignment detection mark sequence 17 is stored in ROM 28 in advance. Each latent image is developed by the developing devices 9M, 9C, 9Y, and 9K in the same manner as described above, and then directly transferred to the transfer belt 2 by the transfer devices 12M, 12C, 12Y, and 12K. However, unlike the color image, each pattern of the misalignment detection mark row 17 is formed so as not to overlap. The misalignment detection mark row 17 transferred to the transport belt 2 is read by the sensors 14, 15 and 16. The CPU 26 corrects the position based on the signals from the sensors 14 to 16. The misalignment detection mark row 17 used for misalignment correction is removed by the cleaning means 18. After the misalignment correction, the normal color image forming operation is restored.

That is, when the inter-paper control shown in FIG. 1 is started, the CPU 26 determines whether or not the condition for forming the alignment mark (positional deviation detection mark sequence) is met (step S1), and the above condition is met. If it is determined that the result has occurred (step S1 / Y), the paper feed roller 100 and the resist roller pair 101 are driven to feed the paper (transfer paper 1) to the transport belt 2 at time t1 (step S2), and the above conditions are met. If it is determined that is not the case (step S1 / N), the transfer paper 1 is sent to the transport belt 2 in the normal time t0 (t1&gt; t0) (step S3).

Here, the color image forming apparatus has at least two execution timings A and B relating to the alignment control. The execution timing A is the timing at which the color image forming apparatus automatically corrects each predetermined number of prints (mode A), and the execution timing B is the timing at which the correction is performed when instructed by the user (mode). B). Mode A is a mode for performing correction during continuous printing. Further, the correction means include a transfer interval adjusting means for making the transfer interval between the transfer sheets 1 wider than the interval during normal printing and narrower than the outer peripheral length of the photoconductor drums 6M, 6C, 6Y, and 6K, and a transfer belt 2. Calculation is performed based on the mark string forming means for forming the misalignment detection mark sequence 17 in the widened area of (or the intermediate transfer body), the alignment sensor for detecting the mark sequence, and the output from the sensor. It is provided with a control means for correcting the misalignment of the unfixed color image during continuous printing. The transport interval adjusting means includes a CPU 26, an electromagnetic clutch 110, a paper feed roller 100, and a resist roller pair 101. For this transfer interval adjusting means, for example, the paper feed control described in JP-A-2000-305337 may be used. The mark row forming means includes each unfixed color image forming portion, a transport belt 2, a CPU 26, and a ROM 28. The control means is composed of CPU26.

The transporting means includes a loop-shaped transport belt 2 for transporting the transfer paper 1 so that the unfixed image is transferred at each unfixed color image forming portion, and a rotary driving means for rotationally driving the transport belt 2. .. The rotary drive means includes a drive roller 3 (see FIG. 2), a motor 32, and a motor drive circuit 33 (claim 4).

The intermediate transfer body includes a loop-shaped transfer belt on which the unfixed image and the mark from each unfixed color image forming unit are transferred, and a rotation driving means (neither shown) for rotationally driving the transfer belt. (Claim 5). The intermediate transfer body includes a transfer drum on which the unfixed color image and the mark from each unfixed color image forming unit are transferred, and a rotating means (neither shown) for rotating the transfer drum (claim). 6).

As described above, the mark row forming means also serves as an unfixed color image forming unit so as to form an unfixed pattern of the mark rows between the formations of the unfixed image, and the control means is an unfixed color image. In order to form the mark row at the forming portion, the timing of forming the unfixed color image is delayed, and the transfer interval adjusting means delays the transfer timing of the transfer paper by the length of the mark row in the transport direction. , CPU26 (claim 7). The length of the transfer paper 1 of the misalignment detection mark row along the transport direction is a length that can detect the misalignment with high accuracy (for example, 4 horizontal lines and 4 diagonal lines are set as a set 8). The length of the set) is preferable (claim 8).

In the above configuration, during continuous printing at predetermined page intervals, the page spacing (paper spacing) of the transfer paper 1 is wider than the page spacing in normal printing operation, and the position shifts to the widened area. By forming a mark row for detection and detecting it, it is possible to form a mark row for detecting misalignment extending along the transport direction, so that misalignment can be detected with high accuracy and high image quality can be improved. Can be planned. Here, FIG. 3 shows a timing chart when forming a pattern of mark rows for detecting misalignment during continuous printing. In the figure, the horizontal axis represents time and the vertical axis represents the voltage of the gate signal. Each gate signal XFGATE M, XFGATE C, XFGATE Y, XFGATE K is a signal indicating an image area in the sub-scanning direction of each color, and these gate signals XFGATE M, XFGATE C, XFGATE Y, XFGATE The unfixed color image forming unit to which K is sent forms an image on the transfer paper (transfer of the unfixed image) at the L level. The gate signal XFGATE of each color is sent from the CPU 26 (see FIG. 2) to the write control board 31 (see FIG. 2) via the bus lines 25 and 29 and the I / O port 24, and is connected to the write control board 31. The unfixed color image forming apparatus forms an unfixed color image with a time difference of approximately the photoconductor pitch (the length of the outer periphery of the photoconductor), and activates an electromagnetic clutch in synchronization with any one of the gate signals. The transfer paper 1 is fed by operating it. The L level time of the gate signal XFGATE of each color is shifted in the order of M, C, Y, and K because the positions of the unfixed color image forming portions are arranged in the order of M, C, Y, and K. Because.

In FIG. 3, the space between the papers between the pages N + 1 and the page N + 2 is made wider than the space in the normal printing operation, and the pattern of the mark row for detecting the misalignment is formed at the widened L level. .. The formed pattern of the misalignment detection mark sequence passes directly above the sensors 14, 15 and 16 fixed in the main body of the color image forming apparatus, and the detection is performed. At this time, for example, when the sensor 14 detects the misalignment between the horizontal line of K in the first set and the horizontal line of K in the second set (not shown) in the pattern of the mark row 17 for misalignment detection, , It means that the misalignment in the sub-scanning direction (arrow 90 direction) has been detected. In addition, when the misalignment between the diagonal line of K in the first set and the diagonal line of K in the second set (not shown) is detected in the pattern of the mark row 17 for misalignment detection, the main scanning direction is detected. This means that a misalignment (direction orthogonal to the arrow 90 direction) has been detected (see Fig. 2, execution timing A).

(Embodiment of Claim 9) The embodiment of claim 9 is characterized in that misalignment is detected with high accuracy even during continuous printing. The difference from the embodiments of claims 1, 2 to 8 is that the color image forming apparatus automatically corrects each predetermined number of prints, or corrects when instructed by the user. This is the point I made. That is, when the color image forming apparatus performs correction, the mark having the same pattern is used regardless of whether the device itself automatically performs the correction (execution timing A) or an instruction from the user (execution timing B). Since the columns are used at the timing shown in Fig. 3, the position shift correction can be performed with high accuracy and high image quality can be expected (the mark array that can be detected with high accuracy is the total length in the transport direction. Because the length is long, there is no choice but to extend the space between the papers). Here, the pattern of the position shift detection mark string formed at the execution timing A is the same as the pattern formed at the execution timing B. That is, it is the pattern described in FIGS. 2 and 3. Therefore, highly accurate positioning is possible without deteriorating the detection accuracy. In addition, since the misalignment of all colors is detected at once, the number of times the paper is stretched can be reduced as much as possible, and therefore the decrease in productivity can be minimized.

(Embodiment of Claim 10) The embodiment of claim 10 is characterized in that the mark sequence has all the colors of the image. In the embodiment of claim 10, since the mark row has all the colors of the image and the position shift detection for all the colors of the image is performed at once in the spread paper, the number of times to extend the space between the papers is increased. It only needs to be done once, and the decrease in productivity due to the correction process can be minimized.

(Embodiment of Claim 11) The embodiment of claim 11 is characterized in that a mark sequence is formed by the colors of two unfixed color image forming portions having the farthest positional relationship. If a mark row is formed with a color pattern having a large misalignment and a mark row is formed with a color pattern with a small misalignment, the color pattern with a large misalignment will be used for correction, which consumes wasteful toner. It will be. Therefore, the mark sequence has the colors of the two unfixed color image forming portions having the farthest positional relationship among the unfixed color image forming portions, so that the mark sequence is formed with a color pattern having less misalignment. This means that toner consumption can be suppressed as much as possible.

(Embodiment of Claim 12) The embodiment of claim 12 is characterized in that a mark sequence is formed by the colors of two unfixed color image forming portions having a large misalignment. By making the mark sequence have the colors of the two unfixed color image forming portions having the largest misalignment among the combinations of the unfixed color images, the mark sequence is not formed with the color pattern with less misalignment. The consumption of toner can be suppressed as much as possible. Here, FIG. 4 shows the relationship between the number of continuous prints and the amount of sub-scanning deviation with respect to BK. In the figure, the horizontal axis indicates the number of continuous sheets (number of prints), and the vertical axis indicates the amount of deviation with respect to black BK. From the figure, it can be seen that the misalignment is large in the order of MK (magenta for black)&gt; CK (cyan for black)&gt; YK (yellow for black). In addition, the amount of deviation with respect to environmental temperature fluctuations tends to be the same. Here, if the patterns shown in FIGS. 9 and 10 are formed for all the colors, the toner consumption also increases. Therefore, for example, Y with a small amount of deviation divides the positional deviation to form the pattern. No detection or correction will be performed. Furthermore, it is possible to divide it into C as well. In this way, the pattern of the position shift detection mark string may be formed, detected, and corrected only for a part of the colors having a large shift change.

(Embodiment of Claim 13) The embodiment of claim 13 is characterized in that at least one component among the components causing the misalignment is detected. By detecting at least one of the main scanning resist component, the main scanning magnification component, the sub-scanning resist component, and the skew component by the mark sequence, a pattern is formed in which the displacement component to be detected between the transfer papers can be detected. It is possible to improve the image quality.

(Embodiment of Claim 14) The embodiment of claim 14 is characterized in that only the main scanning magnification component is detected by the mark sequence. By detecting only the main scanning magnification component by the mark sequence, it is possible to detect only the component with large misalignment fluctuation and reduce the calculation processing load, which saves the calculation and minimizes the decrease in productivity. it can. Here, in the embodiments of claims 13 and 14, the change in the main scanning magnification is abrupt and large among various misalignment components. This is because the lens and the mirror in the exposure device 8 are easily affected by the temperature change, and the lens refractive index changes and the mirror posture changes. Therefore, it is assumed that only the magnification deviation is detected by the pattern formed between the papers. As a result, it is possible to save labor in the arithmetic processing performed by the CPU between papers, and since the printing operation is not interrupted, the decrease in productivity can be minimized.

(Embodiment of Claim 15) The embodiment of claim 15 is characterized in that only the sub-scanning resist component is detected by the mark sequence. By detecting only the sub-scanning resist component by the mark sequence, the calculation can be saved and the decrease in productivity can be minimized. Further, in the embodiments of claims 14 and 15, among the various misalignment components, the change of the sub-scanning resist is rapid and large as shown in FIG. This is because the lens and the mirror in the exposure device 8 are easily affected by the temperature change, and the lens refractive index changes and the mirror posture changes. Another cause is that the diameter of the drive roller 4 for driving the transport belt 2 changes depending on the temperature, the transport speed changes, and the position shifts. Therefore, it is assumed that only the sub-scanning resist misalignment is detected by the pattern formed between the papers. In the case of the patterns in FIGS. 9 and 10, detection is possible only with horizontal lines. As a result, it is possible to save labor in the arithmetic processing performed by the CPU between papers, and since the printing operation is not interrupted, the decrease in productivity can be minimized.

(Embodiment of Claim 16) The embodiment of claim 16 is characterized in that a main scanning resist component, a main scanning magnification component, and a sub-scanning resist component are detected by a mark sequence. By detecting the main scanning resist component, the main scanning magnification component, and the sub-scanning resist component from the mark sequence, the skew component that hardly exists in reality is not detected, and the calculation process can be reduced accordingly. Further, in the embodiment of claim 16, among various misalignment components, the skew misalignment has little change. This is because once the skew deviation is corrected, it occurs due to tilting when the photoconductor is replaced. Therefore, the main scanning resist, the main scanning magnification, and the sub-scanning resist are detected and corrected by the pattern formed between the papers. That is, since all the deviation components other than the skew deviation can be detected and corrected, a high-quality image can be formed. The pattern at this time may be the one shown in FIGS. 9 and 10.

(Embodiment of Claim 17) The embodiment of claim 17 is characterized in that the pattern of the mark row includes a line shape perpendicular to the transport direction of the transfer paper. Since the mark row pattern includes a line shape perpendicular to the transfer direction of the transfer paper, at least a deviation component in the sub-scanning direction can be detected, and high image quality can be achieved. Further, in the embodiment of claim 17, when detecting the deviation in the sub-scanning direction, the line shape perpendicular to the transport direction must be included. The patterns shown in FIGS. 9 and 10 also include a line shape perpendicular to the transport direction.

(Embodiment of Claim 18) In the embodiment of claim 18, the detection sensor for detecting the mark sequence is composed of an optical element and utilizes a change in the amount of specularly reflected light or transmitted light, and the mark sequence The pattern is characterized by including an oblique line shape having a predetermined angle in the transport direction of the transfer paper. The detection sensor that detects the mark sequence consists of an optical element and utilizes a change in the amount of specularly reflected light or transmitted light, and the pattern of the mark sequence has an oblique line shape with a predetermined angle in the transfer direction of the transfer paper. Since it is included, at least the deviation in the main scanning direction can be detected, and the image quality can be improved. Further, in the embodiment of claim 18, when the detection sensors 14, 15 and 16 utilize the change in the amount of specularly reflected light or transmitted light from the belt surface, the magnification and the registration deviation in the main scanning direction are obtained. In order to detect, the pattern to be formed must include diagonal line segments having a predetermined angle with respect to the transport direction as shown in FIGS. 9 and 10. In the patterns in FIGS. 9 and 10, diagonal lines at an angle of 45 ° with respect to the transport direction are used.

(Embodiment of Claim 19) In the embodiment of claim 19, the detection sensor for detecting the mark sequence is composed of an optical element and uses a change in the amount of diffused light, and the pattern of the mark sequence is a transfer paper. It is characterized by including a line shape parallel to or orthogonal to the transport direction of. The detection sensor for detecting the mark sequence is composed of an optical element and utilizes a change in the amount of diffused light. Since the pattern of the mark sequence includes a line shape parallel to the transport direction of the transfer paper, at least a deviation in the main scanning direction Can be detected, and high image quality can be achieved. Further, in the embodiment of claim 19, when the detection sensors 14, 15 and 16 utilize the change in the amount of diffused light on the belt surface, in order to detect the magnification and the resist deviation in the main scanning direction, It is assumed that the pattern to be formed includes a line segment parallel to the transport direction as shown in FIG. FIG. 5 is a diagram showing another embodiment of the mark sequence for detecting misalignment to which the color image forming method of the present invention is applied. This misalignment detection mark row is a plurality of (but not limited to five in the figure) rectangular reference patterns formed on the transport belt in parallel with the transport direction and at predetermined intervals. And a comparison pattern that has the same shape as each reference pattern, has a different color, and is formed so as to gradually shift by a certain length in a direction orthogonal to the transport direction with respect to each reference pattern. ing. For example, taking the case of detecting the main scan deviation of (C-BK) for the comparison pattern of color C with respect to the reference pattern of color BK as an example, C is gradually added to BK as shown in FIG. Create a staggered pattern (to the extent that the sensor can be identified) (1st, 2nd, 3rd, 4th, and 5th steps from the top to the bottom of the figure). That is, in the first row, comparison patterns of approximately the same size as the reference pattern are lined up on the left side of the reference pattern, and in the second row, comparison patterns with a width approximately half the width of the reference pattern are lined up on the left side of the reference pattern, and the third row. In the eyes, only the reference pattern is used, in the fourth row, the comparison pattern having a width half the width of the reference pattern is arranged on the right side of the reference pattern, and in the fifth row, the comparison pattern is arranged on the right side of the reference pattern.

FIG. 6 is a diagram showing the relationship between the amount of diffused light and the number of pattern stages when the position shift detection mark sequence shown in FIG. 5 is detected by the sensor. In FIG. 6, the horizontal axis shows the number of pattern stages, and the vertical axis shows the amount of diffused light (voltage value). When these reference patterns and comparison patterns are formed on the transport belt, the change in the diffused light receiving amount (voltage value) as shown by the wavy line in the graph shown in FIG. 6 is shown, and the light receiving amount becomes almost zero in the third stage. This is because BK has the property of absorbing light, while the other colors C (Y, M) have the property of reflecting light. However, when a position shift detection mark row is formed on the conveyor belt, the change in the diffused light receiving amount (voltage value) when C is shifted in the negative direction becomes as shown by the solid line, and in this case, the position shift detection is performed. At the 4th stage of the mark row, the amount of received light is almost zero, that is, the most suitable state is obtained. In this way, if it is possible to know the number of stages of the pattern with the smallest light receiving amount, the correction amount can be determined.

FIG. 7 is a diagram showing a modified example of the mark sequence for detecting misalignment to which the color image forming method of the present invention is applied. The difference from the misalignment detection mark sequence shown in FIG. 5 is that both the reference pattern and the comparison pattern are orthogonal to the transport direction. The misalignment detection mark rows shown in FIG. 7 are a plurality (but not limited to five in the figure) formed on the transport belt in a direction orthogonal to the transport direction along the transport direction at predetermined intervals. A rectangular reference pattern and a comparison pattern that has the same shape as each reference pattern, has a different color, and is formed so as to be gradually displaced by a certain length in parallel with the transport direction with respect to each reference pattern. It is composed of. Even if such a misalignment detection mark sequence is used, the same effect as that of the misalignment detection mark sequence shown in FIG. 5 can be obtained.

(Embodiment of Claim 20) In the embodiment of claim 20, a latent image is formed on a photoconductor by exposure, and the latent image is developed to form an unfixed color image on recording paper, which is unfixed. It is a color image forming method that corrects the misalignment of an unfixed color image by forming a mark row for alignment on a transfer paper transport means or an intermediate transfer body, detecting the misalignment amount of the mark row, and calculating the misalignment amount. Therefore, based on the output from the sensor, the transfer interval between the transfer sheets is made wider than a predetermined interval, and a plurality of mark rows are formed in the transfer direction in the widened area of the transfer means or the intermediate transfer body to form the mark rows. It is characterized in that it detects and corrects misalignment during continuous printing. By making the transfer interval between the transfer sheets wider than the predetermined interval and forming at least one row of mark rows in the widened region of the transfer means or the intermediate transfer body, it is not necessary to stop the apparatus. By detecting the mark rows formed in the area between the transfer sheets, it is possible to cancel the influence of the speed fluctuation in the transport direction of the transport means or the intermediate transfer body (by averaging the detection results of the mark rows). , The accuracy of misalignment correction can be improved.

(Embodiment of Claim 22) In the embodiment of claim 22, the procedure A for forming an unfixed color image by developing a latent image formed on the photoconductor by exposure to a control means, unfixed. Step B of transferring the color image to the intermediate transfer body and then retransferring it to the transfer paper, or transferring the unfixed color image directly to the transfer paper, procedure C of transferring the recording paper to the transfer means, transfer between the transfer papers. Step D to make the interval wider than the predetermined interval and form at least one row of mark rows in the widened area of the transport means or intermediate transfer material, and step E to detect the mark rows and correct the misalignment during continuous printing. It is characterized by being executed. By making the transfer interval between the transfer sheets wider than the predetermined interval and forming at least one row of mark rows in the widened region of the transfer means or the intermediate transfer body, it is not necessary to stop the apparatus. By detecting the mark rows formed in the area between the transfer sheets, it is possible to cancel the influence of the speed fluctuation in the transport direction of the transport means or the intermediate transfer body (by averaging the detection results of the mark rows). , The accuracy of misalignment correction can be improved.

(Embodiment of Claim 24) The embodiment of claim 24 is a recording medium, and a control means develops a latent image formed on a photoconductor by exposure to form an unfixed color image. Step A, transfer the unfixed color image to the intermediate transfer body and then retransfer it to the transfer paper, or transfer the unfixed color image directly to the transfer paper B, transfer the transfer paper to the transfer means C, The transfer interval between the transfer sheets is made wider than the predetermined interval, and at least one row of mark rows is formed in the widened area of the transport means or the intermediate transfer body. Step D and the mark rows are detected during continuous printing of misalignment correction. It is characterized in that a program for executing step E to be executed is recorded. Here, examples of the recording medium include a magnetic recording device such as an HDD (hard disk driver), a flexible disk, a CDROM, and an MO, and a semiconductor memory. By making the transfer interval between the transfer sheets wider than a predetermined interval and forming at least one row of mark rows in the widened region of the transfer means or the intermediate transfer body, it is not necessary to stop the apparatus. By detecting the mark rows formed in the area between the transfer sheets, it is possible to cancel the influence of the speed fluctuation in the transport direction of the transport means or the intermediate transfer body (by averaging the detection results of the mark rows). , The accuracy of misalignment correction can be improved.

(Other Examples of Conveyance Belt) So far, a method of forming a pattern and a patch on the transport belt 2 to perform alignment has been shown, but the belt is not limited to this, and the same applies to, for example, an intermediate transfer belt. Can be carried out. Further, the present invention is not limited to the belt, and for example, a transfer drum, an intermediate transfer drum, an intermediate transfer roller, or the like may be used.

By the way, there is a demand from the industrial world to minimize downtime due to misalignment detection during continuous printing. Therefore, the present inventor has proposed a color image forming apparatus, a color image forming program, and a recording medium that can accurately correct misalignment even during continuous printing and minimize downtime due to misalignment detection. .. (Embodiment of claim 2) In this image forming method, a latent image is formed on a photoconductor by exposure, the latent image is developed to form an unfixed color image on a recording paper, and a mark row for unfixed alignment is formed by a means for transporting the recording paper. It is a color image forming method that corrects the misalignment of an unfixed color image by forming it on an intermediate transfer body, detecting the amount of misalignment of the mark sequence, and calculating it. The transfer interval is wider than the normal print interval, and multiple mark rows are formed in the transfer direction in the widened area of the transfer means or intermediate transfer body, and the mark rows are detected to correct the misalignment during continuous printing. At the same time, when the misalignment correction is automatically performed, a mark string having a length shorter than the length of the mark string used when the correction is performed according to an instruction from the user is used. FIG. 11 is a diagram showing position fluctuations due to driving of the transport belt shown in the color image forming apparatus of FIG. 8, where the horizontal axis is the time axis and the vertical axis is the fluctuation amount axis. It can be seen that the mark row 170 shown in FIG. 11 is shorter than the length of the mark row 17 shown in FIG. The mark row 170 shown in FIG. 11 consists of four horizontal lines (lines in the direction orthogonal to the transport direction of the transport belt) and four diagonal lines of each color K, Y, C, and M shown in FIG. The mark is one set, and four sets are formed along the transport direction. Each of the four sets of mark rows 170 is adjusted to the position fluctuation phase caused by the drive speed fluctuation such as belt running in the sub-scanning direction (arrow 90 direction), and as shown in FIG. 11, the error in pattern formation and detection is as small as possible. It is formed in consideration of the phase so as to reduce the number. By determining the correction amount from the result of calculating the average of these detection results, it is possible to form a high-quality image with little misalignment of each color and to minimize the downtime due to misalignment detection. In the present embodiment, the case where the length of the mark row 170 is the length of four sets of marks has been described, but the present invention is not limited to this, and the length of the mark row 170 is the length of the mark row 17 It should be shorter than the length of. Further, in the present embodiment, the case where the shape of the mark of the mark row 170 is composed of a line in a direction orthogonal to the transport direction of the transport belt and an oblique line has been described, but the present invention is not limited to this. If the misalignment can be detected, a diagonal line rising to the right and a diagonal line rising to the left may be combined, and the line orthogonal to the transport direction of the transport belt and parallel to the transport direction of the transport belt. It may be combined with a line, and the shape of the pattern constituting the mark itself is not limited to a straight line, and may be a wavy line, an ellipse, an oval, a polygon, or a circle.

(Embodiment of Claim 21) In the embodiment of claim 21, a latent image is formed on the photoconductor by exposure, the latent image is developed to form an unfixed color image on a recording paper, and an unfixed position is formed. It is a color image forming method that corrects the misalignment of an unfixed color image by forming a alignment mark row on a recording paper transport means or an intermediate transfer body, detecting the misalignment amount of the mark row, and calculating the misalignment amount. , Based on the output from the sensor, the transport interval between the recording sheets is made wider than the normal print interval, and a plurality of mark rows are formed in the transport direction in the widened area of the transport means or the intermediate transfer body, and the mark rows are formed. Is detected and the misalignment correction is performed during continuous printing, and when the misalignment correction is automatically performed, a mark string having a length shorter than the length of the mark string used when the correction is performed according to the instruction from the user is used. It is characterized by that. With this configuration, a high-quality image with little misalignment of each color can be formed, and downtime due to misalignment detection can be minimized.

(Embodiment of Claim 23) The embodiment of claim 23 is a procedure for forming an unfixed color image by developing a latent image formed on a photoconductor by exposure to a control means of a color image forming apparatus. A, Step B of transferring the unfixed color image to the intermediate transfer body and then retransferring it to the recording paper, or transferring the unfixed color image directly to the recording paper B, Procedure C of transporting the recording paper to the transfer means, Recording Step D to make the transport interval between papers wider than the predetermined interval and form at least one row of mark rows in the widened area of the transport means or intermediate transfer body and detect the mark rows to correct the misalignment during continuous printing. At the same time, when the misalignment correction is automatically performed, the procedure F is executed using a mark string having a length shorter than the length of the mark string used when the correction is performed according to an instruction from the user. With this configuration, a high-quality image with little misalignment of each color can be formed, and downtime due to misalignment detection can be minimized.

(Embodiment of Claim 25) The embodiment of claim 25 is a procedure for forming an unfixed color image by developing a latent image formed on a photoconductor by exposure to a control means of a color image forming apparatus. A, Step B of transferring the unfixed color image to the intermediate transfer body and then retransferring it to the recording paper, or transferring the unfixed color image directly to the recording paper B, Procedure C of transporting the recording paper to the transfer means, Recording Step D to make the transport interval between papers wider than the predetermined interval and form at least one row of mark rows in the widened area of the transport means or intermediate transfer body and detect the mark rows to correct the misalignment during continuous printing. In addition to performing this, when automatically correcting the misalignment, it is characterized by recording a program that executes step F using a mark string whose length is shorter than the length of the mark string used when correcting according to the instruction from the user. And. With this configuration, a high-quality image with little misalignment of each color can be formed, and downtime due to misalignment detection can be minimized. Here, examples of the recording medium include a magnetic recording device such as an HDD (hard disk driver), a flexible disk, a CDROM, and an MO, and a semiconductor memory.

<figref num="1">It is a flowchart which shows one Embodiment of the color image formation method of this invention.</figref><figref num="2">It is a block diagram which shows one Embodiment of the color image forming apparatus to which the color image forming method of this invention is applied.</figref><figref num="3">It is a timing chart at the time of forming the pattern of the mark string for position deviation detection during continuous printing.</figref><figref num="4">It is a figure which showed the relationship between the number of continuous prints and the amount of sub-scanning deviation with respect to BK.</figref><figref num="5">It is a figure which shows the other embodiment of the mark string for displacement detection to which the color image forming method of this invention is applied.</figref><figref num="6">It is a figure which shows the relationship between the amount of diffused light and the number of pattern steps when the position shift detection mark string shown in FIG. 5 is detected by a sensor.</figref><figref num="7">It is a figure which shows the modification of the mark string for position displacement detection to which the color image forming method of this invention was applied.</figref><figref num="8">It is a block diagram of a color image forming apparatus called a tandem type in which an image forming part is arranged along a transport belt.</figref><figref num="9">It is a figure which shows a part of the toner mark row 17 for position displacement detection formed on the transport belt 2 shown in the color image forming apparatus of FIG.</figref><figref num="10">It is a figure which shows the position variation by driving of the transport belt shown in the color image forming apparatus of FIG.</figref><figref num="11">It is a figure which shows the position variation by driving of the transport belt shown in the color image forming apparatus of FIG.</figref>

Code description

14, 15, 16 Sensors 17, 170 Toner mark row for misalignment detection (mark row for misalignment detection, mark row) 19 AMP (amplifier) 20 Filter 21 A / D (analog / digital converter) 22 Sampling control unit 23 FIFO 24 I / O 25 Data bus line 26 CPU 27 RAM 28 ROM 29 Address bus line 30 Light emission control unit 31 Write control board 32 Motor 33 Motor drive circuit 34 Clutch drive circuit 100 Feed roller 110 Electromagnetic clutch