JP2005292760A - Color image forming apparatus, color image forming method, color image forming program and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color image forming apparatus with which displacement can accurately be corrected even in the course of consecutive printing, and to provide a color image forming method, a color image forming program and a recording medium. <P>SOLUTION: A conveyance interval between sheets of recording paper is made longer than a prescribed interval. At least one line of marks is formed in an area of a conveying means or intermediate transfer body, by which the interval is made longer. This eliminates the need to stop the apparatus. Detecting the line of marks formed in the area between the sheets of recording paper (calculating the average of the results of the detection of the lines of marks) makes it possible to nullify the adverse effect of the speed change of the conveying means or intermediate transfer body in the conveyance direction. Accordingly, accuracy in correcting displacement can be improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

In general, a color image forming apparatus includes an image forming unit and an environmental state detecting unit that detects an environmental state including temperature and humidity in the vicinity of the image forming unit. In this apparatus, when the detected value of the environmental condition including the temperature and humidity of the environmental condition detecting means exceeds a predetermined value during the continuous formation of a plurality of images, and the detected value exceeds the predetermined value. If a predetermined number of images are formed, a pattern image forming unit for alignment is formed between the images, and a predetermined pattern image is formed on the pattern reading unit. It is read and the alignment control is performed by the control means (for example, see Patent Document 1).
As an image forming process of the image forming apparatus (color image forming apparatus) using the above conventional technique, there is the following.

FIG. 8 shows a configuration of a color image forming apparatus called a tandem type in which image forming units are arranged along a conveying belt. This apparatus is a direct transfer type apparatus that does not use an intermediate transfer member.
Four image forming units that form images of different colors (magenta: M, cyan: C, yellow: Y, black: K) are arranged in a line along a conveying belt 2 that conveys a transfer sheet 1 as a recording sheet. Has been placed. The transport belt 2 is constructed by a drive roller 3 that rotates and a driven roller 4 that rotates and is driven to rotate in the direction of the arrow by the rotation of the transport roller 3. A paper feed tray 5 in which the transfer paper 1 is stored is provided below the conveyance belt 2. The transfer sheet at the uppermost position among the stored transfer sheets 1 is fed at the time of image formation and is attracted onto the transport belt 2 by electrostatic attraction.

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

After the transfer, the photoreceptor drum 6M is cleaned with unnecessary toner remaining on the drum surface by the photoreceptor cleaner 10M to prepare for the next image formation.
As described above, the transfer paper 1 on which the single color (magenta) is transferred by the first image forming unit (magenta) is transported by the transport belt 2 to the second image forming unit (cyan). Also in the second image forming unit, the toner image (cyan) formed on the photosensitive drum 6C is transferred onto 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 similarly formed toner images are transferred to form a color image.
The transfer paper 1 on which a color image has been formed by passing through the fourth image forming section is peeled off from the conveying belt 2, fixed by a fixing device 13, and then discharged from the color image forming apparatus.

Further, detection sensors 14, 15 and 16 for detecting the pattern of the misalignment detection mark row are attached above the conveyance belt 2 of the color image forming apparatus main body.
Reference numeral 100 denotes a paper feed roller, and a central axis 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 registration roller pair, and the central axis of one of the rollers is connected to the output shaft of the drive motor, and the registration roller pair 101 is disposed in a substantially intimate contact state. The transfer paper 1 is separated and fed by the paper feed roller 100 and the registration roller pair 101.

FIG. 9 shows a part of the misregistration detection toner mark row 17 formed on the conveyance belt 2 shown in the color image forming apparatus of FIG. FIG. 10 is a diagram showing the position variation due to the driving of the conveying 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 variation amount axis.
Each mark K, Y, C, M shown in FIG. 9 is composed of a set of four horizontal lines (lines perpendicular to the transport direction of the transport belt) and four diagonal lines. Mark rows 17 are formed along the eight sets of conveying directions. Each of the eight sets of mark rows 17 is adjusted to a position fluctuation phase caused by fluctuations in driving speed such as belt running in the sub-scanning direction (arrow 90 direction), and errors in pattern formation and detection are minimized as shown in FIG. It is formed in consideration of the phase so as to decrease. 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 lines and diagonal lines are formed and detected by sensors 14, 15, and 16 arranged in the main scanning direction, and skew and sub-scanning with respect to the reference color (in this case, BK) Registration deviation, main scanning registration deviation, and main scanning magnification error can be measured, and by shifting the image in the direction opposite to the position deviation direction by 1/2 of the maximum position deviation amount detected by each sensor, It is possible to correct the shift amount due to the magnification deviation in the main scanning direction so as to be inconspicuous. Various deviation amounts, correction amount calculation and correction execution instructions are executed by the main CPU. The detected pattern is cleaned by the cleaning means 18.
Such misregistration correction was executed by an instruction from the user menu, service menu, or printer driver of the apparatus (this misregistration correction timing is timing B, and the misregistration correction automatically performed by the color image forming apparatus side) Is the timing A. For example, see Patent Document 2).
Japanese Patent No. 3450402 JP 2003-186278 A

However, in the above-described prior art, the interval between the recording sheets is made as small as possible in order to increase the productivity during continuous printing. In this case, it is impossible to form a pattern having a long total pattern length, and it is necessary to detect the pattern with a short pattern length, so that the detection accuracy is lowered, and a positional shift occurs, resulting in image degradation.
SUMMARY OF THE INVENTION 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 that can accurately perform misregistration correction even during continuous printing.

In order to solve the above-mentioned problems, the invention described in claim 1 is a plurality of images that are arranged along the conveyance direction of the recording paper and that develop a latent image formed on the photosensitive member by exposure to form an unfixed color image. An unfixed color image forming portion; and transfer means for transferring the unfixed color image to the recording sheet after transferring the unfixed color image to an intermediate transfer member, or transferring the unfixed color image directly to the recording sheet; A color image forming apparatus including a conveyance unit configured to convey a recording sheet to the transfer unit, wherein a conveyance interval between the recording sheets is wider than a predetermined interval, and the conveyance unit or the intermediate transfer member is widened. The image processing apparatus is characterized in that at least one mark row is formed in the area, and the correction means for detecting the mark row and correcting the misalignment during continuous printing is provided.
According to the first aspect of the present invention, the conveying interval between the recording sheets is made wider than a predetermined interval, and the apparatus is stopped by forming at least one mark row in the widened area of the conveying means or the intermediate transfer member. There is no need to do it. By detecting the mark rows formed in the area between the recording sheets, the influence of the speed fluctuation in the carrying direction of the conveying means or the intermediate transfer member can be canceled (by taking the average of the detection results of the mark rows). Therefore, the accuracy of positional deviation correction can be improved.

According to a second aspect of the present invention, there are provided a plurality of unfixed color image forming units that are arranged along the recording sheet conveyance direction and that develop a latent image formed on a photoconductor by exposure to form an unfixed color image. A transfer means for transferring the unfixed color image to the recording paper after being transferred to an intermediate transfer member, or transferring the unfixed color image directly to the recording paper; and the recording paper to the transfer means. A color image forming apparatus including a conveying unit configured to convey, wherein a conveyance interval between the recording sheets is wider than a predetermined interval, and at least one mark row is formed in a widened area of the conveying unit or the intermediate transfer member. If the mark row is detected and misalignment correction is performed during continuous printing, and the misalignment correction is automatically performed, the length of the mark row used when the correction is performed according to an instruction from the user Characterized by using the mark row of shorter length.
According to the second aspect of the present invention, since the alignment mark length formed between the sheets can be shortened as much as possible, the decrease in productivity can be minimized.

According to a third aspect of the present invention, in the invention according to the first or second aspect, the correction unit makes the conveyance interval between the recording sheets wider than the interval during normal printing and narrower than the outer peripheral length of the photoconductor. Based on an interval adjusting means, a mark line forming means for forming a mark line in a widened area of the conveying means or the intermediate transfer member, a positioning sensor for detecting the mark line, and an output from the sensor And a control means for performing misregistration correction of the unfixed color image during continuous printing.
According to the third aspect of the present invention, since the conveyance interval between the recording sheets is larger than the interval during normal printing and narrower than the outer peripheral length of the photosensitive member, the positional deviation is corrected. The length of the recording paper can be set to a length with which the positional deviation can be detected with high accuracy, and the image quality of the recording paper can be improved.

  According to a fourth aspect of the invention, in the invention according to any one of the first to third aspects of the invention, the conveying unit is configured to transfer the unfixed image onto the recording sheet at each unfixed color image forming unit. A loop-shaped transport belt that transports the transport belt and a rotation drive unit that rotationally drives the transport belt.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to third aspects, an unfixed image and the mark row from the respective unfixed color image forming portions are transferred to the intermediate transfer member. It is characterized by comprising a loop-shaped transfer belt and rotation driving means for rotating the transfer belt.

  According to a sixth aspect of the present invention, in the invention according to any one of the first to third aspects, the intermediate transfer member is configured to transfer the unfixed color image and the mark row from the unfixed color image forming unit. And a rotating means for rotating the transfer drum.

  According to a seventh aspect of the present invention, in the invention according to any one of the first to sixth aspects, the mark row forming unit forms an unfixed pattern of the mark row between formations of the unfixed image. And the control means delays the timing for forming the unfixed color image so as to form the mark row in the unfixed color image forming unit. The conveyance interval adjusting means delays the conveyance timing of the recording paper by the length of the mark row in the conveyance direction.

The invention according to an eighth aspect is the invention according to any one of the first to seventh aspects, wherein the length of the mark row along the conveyance direction of the recording paper can detect a positional deviation with high accuracy. It is a length that can be made.
According to the eighth aspect of the present invention, since the length of the mark row along the recording sheet conveyance direction is a length that can detect misalignment with high accuracy, (the average of the detection results of the mark row) Therefore, the influence of the conveying direction of the conveying means or the intermediate transfer member can be canceled, and the accuracy of the positional deviation correction can be improved.

The invention according to claim 9 is the invention according to any one of claims 1 to 8, wherein the correction means automatically corrects every predetermined number of prints or receives an instruction from a user. Sometimes correction is performed.
According to the ninth aspect of the present invention, when the correction is automatically made every predetermined number of printed sheets, the maintenance becomes easy, and when the correction is made when an instruction from the user is given, the conveyance system It can be adjusted when replacing parts, and high image quality can be maintained.

According to a tenth aspect of the present invention, in the invention according to any one of the first to ninth aspects, the mark row has all colors of image forming colors.
According to the tenth aspect of the present invention, since the mark row composed of all the colors of the image forming color is formed in one area, the number of times of widening the interval between the recording papers is only one, and the productivity (number of prints) is achieved. Can be suppressed to a minimum of 1 sheet or less.

According to an eleventh aspect of the present invention, in the invention according to any one of the first to ninth aspects, the two unfixed color image formations in which the mark row is farthest among the unfixed color image forming portions. It has the color of a part.
According to the eleventh aspect of the invention, since the mark row has the colors of the two unfixed color image forming portions that are the farthest among the unfixed color image forming portions, (the average of the detection results of the mark row) The effect of speed fluctuations in the transport direction of the transport means or intermediate transfer plate can be canceled, making it easier to detect misalignment and minimizing the consumption of toner required for image formation. Can do.

According to a twelfth aspect of the present invention, in the invention according to any one of the first to ninth aspects, the mark row is formed of two unfixed color image forming portions having the largest positional deviation among combinations of unfixed color images. It has a color.
According to the twelfth aspect of the present invention, since the mark row has the colors of the two unfixed color image forming portions having the largest positional deviation among the combinations of the unfixed color images, the detection of the positional deviation is easily grasped. At the same time, it is possible to minimize the consumption of toner necessary for image formation.

According to a thirteenth aspect of the present invention, in the invention according to any one of the tenth to twelfth aspects, at least one of a main scanning resist component, a main scanning magnification component, a sub-scanning resist component, and a skew component depending on the mark row. A component is detected.
According to the thirteenth aspect of the present invention, 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 row. A pattern capable of detecting a shift component can be formed, and high image quality can be achieved.

The invention according to claim 14 is the invention according to claim 13, wherein only the main scanning magnification component is detected by the mark row.
According to the fourteenth aspect of the present invention, since only the main scanning magnification component is detected by the mark row, the calculation process can be saved, the positional deviation can be corrected quickly, and the reduction in productivity can be minimized. .

According to a fifteenth aspect of the invention, in the thirteenth aspect of the invention, only the sub-scanning resist component is detected by the mark row.
According to the fifteenth aspect of the present invention, since only the sub-scanning resist component is detected by the mark row, the calculation processing is saved, and the reduction in productivity can be minimized.

A sixteenth aspect of the invention is characterized in that, in the thirteenth aspect of the invention, a main scanning resist component, a main scanning magnification component, and a sub-scanning resist component are detected by the mark row.
According to the sixteenth aspect of the present invention, since the main scanning resist component, the main scanning magnification component, and the sub-scanning resist component are detected from the mark row, there is no detection of the skew component that does not actually exist, and the calculation processing is accordingly performed. Labor saving can be achieved.

The invention according to claim 17 is the invention according to claim 13, wherein the pattern of the mark row includes a line shape perpendicular to the conveyance direction of the recording paper.
According to the seventeenth aspect of the present invention, since the pattern of the mark row includes a line shape perpendicular to the conveyance direction of the recording paper, it is possible to detect at least a deviation component in the sub-scanning direction and to improve image quality. Can do.

The invention according to claim 18 is the invention according to claim 13, wherein the detection sensor for detecting the mark row comprises an optical element, and utilizes a change in specular reflection light or transmitted light amount. The pattern includes an oblique line shape having a predetermined angle in the conveyance direction of the recording paper.
According to the eighteenth aspect of the present invention, the detection sensor for detecting the mark row is composed of an optical element, and utilizes a change in specular reflection light or transmitted light amount, and the pattern of the mark row is in the conveyance direction of the recording paper. Since it includes an oblique line shape having a predetermined angle, it is possible to detect at least a shift in the main scanning direction and to improve image quality.

According to a nineteenth aspect of the invention, in the thirteenth aspect of the invention, the detection sensor for detecting the mark row comprises an optical element and utilizes a change in the amount of diffused light, and the pattern of the mark row is the record. It includes a line shape that is parallel to or orthogonal to the sheet conveyance direction.
According to the nineteenth aspect of the present invention, the detection sensor for detecting the mark row is made of an optical element and utilizes a change in the amount of diffused light, and the pattern of the mark row is a line shape parallel to the conveyance direction of the recording paper. Therefore, at least a shift in the main scanning direction can be detected, and high image quality can be achieved.

According to a twentieth aspect of the present invention, a latent image is formed on a photosensitive member by exposure, the latent image is developed to form an unfixed color image on a recording sheet, and a mark row for unfixed alignment is formed on the recording sheet. A color image forming method for correcting the positional deviation of the unfixed color image by detecting and calculating the amount of positional deviation of the mark row, which is formed on the conveying means or intermediate transfer member, and outputting from the sensor Based on the above, the conveyance interval between the recording sheets is made wider than a predetermined interval, a plurality of mark rows are formed in the conveyance direction in the widened area of the conveyance means or the intermediate transfer member, and the mark rows are detected. The positional deviation correction is performed during continuous printing.
According to the invention of claim 20, the apparatus is stopped by making the conveyance interval between recording sheets wider than a predetermined interval and forming at least one mark row in the widened area of the conveyance means or the intermediate transfer member. There is no need to do it. By detecting the mark rows formed in the area between the recording sheets, the influence of the speed fluctuation in the carrying direction of the conveying means or the intermediate transfer member can be canceled (by taking the average of the detection results of the mark rows). Therefore, the accuracy of positional deviation correction can be improved.

According to a twenty-first aspect of the present invention, a latent image is formed on a photoreceptor by exposure, the latent image is developed to form an unfixed color image on a recording sheet, and a mark row for unfixed alignment is formed on the recording sheet. A color image forming method for correcting the positional deviation of the unfixed color image by detecting and calculating the amount of positional deviation of the mark row, which is formed on the conveying means or intermediate transfer member, and outputting from the sensor Based on the above, the conveyance interval between the recording sheets is made wider than the normal print interval, a plurality of mark rows are formed in the conveyance direction in the widened area of the conveyance means or the intermediate transfer member, and the mark rows are formed. When detecting and performing misregistration correction during continuous printing and automatically performing misregistration correction, a mark string having a length shorter than that of the mark string used when the correction is performed by an instruction from the user is used. It is characterized in.
According to the twenty-first aspect of the present invention, since the alignment mark length formed between the sheets can be made as short as possible, the reduction in productivity can be minimized.

According to a twenty-second aspect of the present invention, in the control means of the color image forming apparatus, the latent image formed on the photoconductor by exposure is developed to form an unfixed color image, and the unfixed color image is After transferring to the transfer body, transfer again to the recording paper or transfer the unfixed color image directly to the recording paper, Procedure C for transporting the recording paper to the transfer means, between the recording paper Procedure D for forming the at least one mark row in the widened area of the transport means or the intermediate transfer body by making the transport interval wider than a predetermined interval, and detecting the mark row and performing positional deviation correction during continuous printing The procedure E is performed.
According to the invention of claim 22, the apparatus is stopped by making the conveyance interval between the recording sheets wider than a predetermined interval and forming at least one mark row in the widened area of the conveyance means or the intermediate transfer member. There is no need to do it. By detecting the mark rows formed in the area between the recording sheets, the influence of the speed fluctuation in the carrying direction of the conveying means or the intermediate transfer member can be canceled (by taking the average of the detection results of the mark rows). Therefore, the accuracy of positional deviation correction can be improved.

According to a twenty-third aspect of the present invention, in the control means of the color image forming apparatus, the latent image formed on the photoreceptor by exposure is developed to form an unfixed color image, and the unfixed color image is After transferring to the transfer body, transfer again to the recording paper or transfer the unfixed color image directly to the recording paper, Procedure C for transporting the recording paper to the transfer means, between the recording paper Procedure D for forming the at least one mark row in the widened area of the transport means or the intermediate transfer body by making the transport interval wider than a predetermined interval, and detecting the mark row and performing positional deviation correction during continuous printing In addition, when the position deviation correction is automatically performed, the procedure F using the mark row having a length shorter than the length of the mark row used when the correction is performed by an instruction from the user is executed. And butterflies.
According to the twenty-third aspect of the present invention, the length of the alignment mark formed between the sheets can be shortened as much as possible, so that the reduction in productivity can be minimized.

According to a twenty-fourth aspect of the present invention, in the control means of the color image forming apparatus, the latent image formed on the photoconductor by exposure is developed to form an unfixed color image. After transferring to the transfer body, transfer again to the recording paper or transfer the unfixed color image directly to the recording paper, Procedure C for transporting the recording paper to the transfer means, between the recording paper Procedure D for forming the at least one mark row in the widened area of the transport means or the intermediate transfer body by making the transport interval wider than a predetermined interval, and detecting the mark row and performing positional deviation correction during continuous printing A program for executing the procedure E to be performed is recorded.
According to the twenty-fourth aspect of the invention, the apparatus is stopped by making the conveyance interval between the recording sheets wider than a predetermined interval and forming at least one mark row in the widened area of the conveyance means or the intermediate transfer member. There is no need to do it. By detecting the mark rows formed in the area between the recording sheets, the influence of the speed fluctuation in the carrying direction of the carrying means or the intermediate transfer member can be canceled (by taking the average of the detection results of the mark rows). Therefore, the accuracy of positional deviation correction can be improved.

According to the 25th aspect of the present invention, in the control means of the color image forming apparatus, the latent image formed on the photoconductor by exposure is developed to form an unfixed color image, and the unfixed color image is After transferring to the transfer body, transfer again to the recording paper or transfer the unfixed color image directly to the recording paper, Procedure C for transporting the recording paper to the transfer means, between the recording paper Procedure D for forming the at least one mark row in the widened area of the transport means or the intermediate transfer body by making the transport interval wider than a predetermined interval, and detecting the mark row and performing positional deviation correction during continuous printing In addition, when performing the misalignment correction automatically, a program for executing the procedure F that uses a mark string shorter than the mark string used when the correction is performed according to an instruction from the user. And characterized by recording the beam.
According to the invention described in claim 25, the length of the alignment mark formed between the sheets can be shortened as much as possible, so that the decrease in productivity can be minimized.

  By making the conveyance interval between the recording sheets wider than a predetermined interval and forming at least one mark row in the widened area of the conveyance means or the intermediate transfer member, it is not necessary to stop the apparatus. By detecting the mark rows formed in the area between the recording sheets, the influence of speed fluctuations in the carrying direction of the conveying means or intermediate transfer member can be canceled (by taking the average of the detection results of the mark rows). Since the accuracy of misregistration 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 that can perform misregistration correction even during continuous printing. be able to.

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

Image data is input to the writing control board 31 and a control signal is input from an I / O (input / output port) 24. Each unfixed color image forming unit forms an unfixed color image based on these image data and control signals.
The sensor 14 (15, 16) connected to the light emission amount control unit 30 includes a light emitting unit (for example, a light emitting diode) and a light receiving unit (for example, a phototransistor). The light emission amount control unit 30 has a function of controlling the light emission amount of the light emitting unit. The light receiving part of the sensor 14 (15, 16) is connected to an amplifier AMP19, and a filter 20, an A / D (analog / digital converter) 21 and a 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 sensors 14 (15, 16) reflect the reflected light of the light applied to the misregistration detection toner mark row (position misalignment detection mark row or mark row) 17 formed on the transport belt (or transfer belt). Convert to electrical signal. In the color image forming apparatus main body, at least one sensor 14 (15, 16) for detecting misalignment in a direction (main scanning direction) perpendicular to the conveying direction of the conveying belt 2 (or intermediate transfer member) as a conveying member. The position deviation amount of the position detection mark is detected, calculated, and the position of the unfixed color image is corrected.

Here, for the arithmetic processing, for example, arithmetic processing described in JP-A-11-65208, JP-A-2002-160398, and JP-A-2002-207337 is used. A signal obtained by the sensor 14 (15, 16) is amplified by an amplifier AMP19, and a frequency component of a frequency (for example, several hundred Hz) or more required by a filter (low-pass filter) 20 is cut.
The signal is converted from analog data to digital data by the A / D 21. 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. Although only the configuration of one sensor 14 is shown here, the other sensors 15 and 16 have the same configuration and are omitted.
After the detection of the pattern of the misalignment detection mark row 17 is completed, the data stored in the ROM 28 is loaded into the CPU 26 and the RAM 27 via the I / O port 24 by the data bus line 25, and the CPU 26 performs various operations. An arithmetic process for calculating the deviation amount and an arithmetic process for optimizing the image forming conditions are performed.

On the other hand, the ROM 28 stores various programs including a program for calculating various deviation amounts and a program for performing calculation processing for optimizing image forming conditions. The address bus line 29 designates a ROM address, a RAM address, and various input / output devices. Further, the CPU 26 monitors the detection signal from the detection sensor 14 (15, 16) at an appropriate timing, and the light emitting portions of the conveyor belt 2 (see FIG. 8) and the sensor 14 (15, 16) are deteriorated. However, the light emission amount control unit 30 controls the light emission amount so that detection can be performed reliably, and the level of the light reception signal from the light receiving unit is controlled to be always constant.
Based on the correction amount obtained from the detection result of the pattern of the misalignment detection mark row 17, the CPU 26 changes the frequency based on the change of the main and sub-registration, the correction of the skew, and the magnification error. For that, set it. The write control board 31 is provided with a device capable of setting the output frequency very finely, for example, a clock generator using a voltage controlled oscillator (VCO) for each color including the reference color. This output is used as an image clock.

(Embodiments of claims 1, 3 to 15)
The first, third, and fifteenth embodiments are characterized in that misregistration is detected with high accuracy even during continuous printing.
First, the photosensitive drums 6M, 6C, 6Y, and 6K are charged by the chargers 7M, 7C, 7Y, and 7K while rotating in the direction of the arrow, and the laser light sources 5 are applied to the charged photosensitive drums 6M, 6C, 6Y, and 6K. The latent images are formed on the photosensitive drums 6M, 6C, 6Y, and 6K by the exposure from, and the latent images are developed by the developing units 9M, 9C, 9Y, and 9K to form unfixed color images, respectively. When 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 conveyed to the fixing device 13 by the conveyor belt 2, the unfixed color image is unfixed by the fixing device 13. A color image is formed on the transfer paper 1 by fixing the image. When an unfixed color image is transferred from the photosensitive drums 6M, 6C, 6Y, and 6K to the transfer sheet 1, excess toner is transferred to the photosensitive drums 6M, 6C, and 6Y by the photosensitive cleaners 10M, 10C, 10Y, and 10K. , 6K, and the next latent image is formed.
The above is the normal color image forming operation.

  Here, the transfer paper 1 is transported by a transport belt 2 as a transport body (in the case of an intermediate transfer type, an intermediate transfer body is provided, and an unfixed color image of each color is overlaid on the intermediate transfer body and then onto 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 (inter-paper space) between the transfer sheets 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 is performed every time a predetermined number of prints (for example, 5000) of color images are formed, or when a user replaces a component. Therefore, when a misregistration correction instruction is input to the CPU 26, the CPU 26 waits for the conveyance of the transfer paper 1 on the conveyance belt 2 by the length of the misalignment detection mark row 17 and also transfers the transfer paper. During the waiting time 1, a latent image of the misregistration detection mark row 17 is formed on each of the photosensitive drums 6M, 6C, 6Y, and 6K. The misalignment detection mark row 17 is stored in the 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 conveying belt 2 by the transfer devices 12M, 12C, 12Y, and 12K. However, unlike the color image, each pattern of the misregistration detection mark row 17 is formed so as not to overlap. The misalignment detection mark row 17 transferred to the conveyor belt 2 is read by the sensors 14, 15, and 16. The CPU 26 performs position correction based on signals from the sensors 14-16. The misalignment detection mark row 17 used for misalignment correction is removed by the cleaning means 18. After the positional deviation correction, the normal color image forming operation is restored.

  That is, when the sheet spacing control shown in FIG. 1 is started, the CPU 26 determines whether or not a condition for forming an alignment mark (a misalignment detection mark row) has been satisfied (step S1). If it is determined (step S1 / Y), the paper feeding roller 100 and the registration roller pair 101 are driven to feed paper (transfer paper 1) to the conveying belt 2 at time t1 (step S2). If it is determined that it is not (step S1 / N), the transfer paper 1 is sent to the transport belt 2 at the normal time t0 (t1> t0) (step S3).

Here, the color image forming apparatus has at least two execution timings A and B related to the alignment control. The execution timing A is a timing at which the color image forming apparatus automatically performs correction every predetermined number of prints (mode A), and the execution timing B is a timing at which correction is performed when an instruction is given from the user (mode). B). Mode A is a mode for performing correction during continuous printing.
Further, the correction means includes a conveyance interval adjusting means for making the conveyance interval between the transfer sheets 1 wider than the interval during normal printing and smaller than the outer peripheral length of the photosensitive drums 6M, 6C, 6Y, 6K, and the conveyance belt 2. (Or an intermediate transfer member) A mark row forming means for forming the misalignment detection mark row 17 in a widened area, a positioning sensor for detecting the mark row, and an operation based on an output from the sensor And a control means for performing misregistration correction of unfixed color images during continuous printing.
The conveyance interval adjusting means includes a CPU 26, an electromagnetic clutch 110, a paper feed roller 100, and a registration roller pair 101. For example, the sheet feeding control described in Japanese Patent Application Laid-Open No. 2000-305337 may be used as the conveyance interval adjusting unit. The mark row forming unit includes each unfixed color image forming unit, the conveyance belt 2, the CPU 26, and the ROM 28. The control means is constituted by a CPU 26.

  The transport unit includes a loop-shaped transport belt 2 that transports the transfer paper 1 so that an unfixed image is transferred at each unfixed color image forming unit, and a rotation drive unit that rotationally drives the transport belt 2. . The rotation drive means is composed of a drive roller 3 (see FIG. 2), a motor 32, and a motor drive circuit 33 (Claim 4).

The intermediate transfer member includes a loop-shaped transfer belt to which an unfixed image and a mark from each unfixed color image forming unit are transferred, and a rotation drive unit (none of which is shown) that drives the transfer belt to rotate. (Claim 5).
The intermediate transfer member includes a transfer drum to which the unfixed color image and the mark from each unfixed color image forming unit are transferred, and a rotating unit (none of which is shown) that rotates the transfer drum. 6).

The mark row forming unit also serves as an unfixed color image forming unit so as to form an unfixed pattern of the mark row between formations of unfixed images as described above. In order to form a mark row in the forming unit, the timing for forming an unfixed color image is delayed, and the conveyance interval adjusting means delays the timing for carrying the transfer paper by the length of the mark row in the carrying direction. And the CPU 26 (Claim 7).
The length of the misregistration detection mark row along the conveyance direction of the transfer paper 1 is a length that can detect misregistration with high accuracy (for example, a set of four horizontal lines and four oblique lines as one set 8. It is preferable that the length of the pair).

In the above configuration, during continuous printing at a predetermined page interval, the page interval (inter-paper) of the transfer sheet 1 is made wider than the page interval in the normal printing operation, and the position is shifted in the widened area. By forming and detecting a detection mark row, it is possible to form a misalignment detection mark row extending along the transport direction, so that it is possible to detect misalignment with high accuracy and to improve image quality. Can be planned.
Here, FIG. 3 shows a timing chart when the pattern of the misalignment detection mark row is formed 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 the image area of each color in the sub-scanning direction. The color image forming unit forms an image on the transfer paper (transfer of an unfixed image) at the L level. The gate signal XFGATE for 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 connected to the write control board 31. The unfixed color image forming apparatus forms an unfixed color image with a time difference approximately equal to the photoreceptor pitch (the length of the outer circumference of the photoreceptor), and an electromagnetic clutch in synchronization with any one of the gate signals. The transfer paper 1 is fed by operating. Note that the L level time of the gate signal XFGATE for each color is shifted in the order of M, C, Y, K. The positions of the unfixed color image forming units are arranged in the order of M, C, Y, K. Because.

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

(Embodiment of Claim 9)
The embodiment of claim 9 is characterized in that the positional deviation is detected with high accuracy even during continuous printing.
The difference from the first, second, and eighth embodiments is that the color image forming apparatus automatically corrects for every predetermined number of prints, or corrects when a user gives an instruction. This is the point.
In other words, when the color image forming apparatus performs correction, the mark having the same pattern is used regardless of whether the apparatus itself automatically performs (execution timing A) or in response to an instruction from the user (execution timing B). Since it is performed at the timing shown in FIG. 3 using a row, it is possible to correct the misalignment with high accuracy and to expect high image quality (the mark row that can be detected with high accuracy is the total length in the transport direction). This is because the length becomes longer, and the gap between the papers must be extended).
Here, the pattern of the misalignment detection mark row formed at the execution timing A is the same as the pattern formed at the execution timing B. That is, the pattern described in FIGS. Therefore, highly accurate alignment is possible without deteriorating detection accuracy. In addition, since the misregistration of all colors is detected at one time, the number of times that the gap between the sheets is extended can be reduced as much as possible, so that the reduction in productivity can be minimized.

(Embodiment of claim 10)
The embodiment of claim 10 is characterized in that the mark row has all colors of image formation.
In the embodiment of the tenth aspect, the mark row has all the colors of the image formation, and the misalignment detection for all the colors of the image formation color is performed at once between the spread papers. This is only necessary once, and the decrease in productivity associated with the correction process can be minimized.

(Embodiment of claim 11)
The embodiment of claim 11 is characterized in that the mark row is formed with the colors of the two unfixed color image forming portions having the farthest positional relationship.
If a mark row is formed with a color pattern with a large positional deviation and a mark row is formed with a color pattern with a small positional deviation, the correction is made with a color pattern with a large positional deviation, and wasteful toner is consumed. It will be.
Therefore, the mark row has the color of the two unfixed color image forming portions having the farthest positional relationship among the unfixed color image forming portions, thereby forming the mark row with a color pattern with little misalignment. Therefore, toner consumption can be suppressed as much as possible.

(Embodiment of claim 12)
The embodiment of claim 12 is characterized in that the mark row is formed with the colors of the two unfixed color image forming portions where the positional deviation becomes large.
By providing the mark row with the colors of the two unfixed color image forming portions that have the largest positional deviation among the combinations of unfixed color images, the mark row is not formed with a color pattern with little positional deviation. As a result, toner consumption can be minimized.
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 continuous number of sheets (number of printed sheets), and the vertical axis indicates the amount of deviation from the black BK.
From the figure, it can be seen that the positional deviation is large in the order of MK (magenta for black)> CK (cyan for black)> YK (yellow for black). Also, the amount of deviation with respect to environmental temperature fluctuations has the same tendency. Here, if the patterns as shown in FIGS. 9 and 10 are formed for all colors, the toner consumption also increases. For example, Y with a small amount of deviation divides the positional deviation, Detection and correction are not performed. Furthermore, it is conceivable that C is divisible. In this way, the formation, detection, and correction of the pattern of the misregistration detection mark row may be performed only for a part of the colors having a large deviation change.

(Embodiment of Claim 13)
An embodiment of the thirteenth aspect is characterized in that at least one component among components causing a positional shift is detected.
By detecting at least one of the main scanning resist component, main scanning magnification component, sub-scanning resist component, and skew component from the mark row, a pattern capable of detecting a shift component to be detected between transfer sheets is formed. Image quality can be improved.

(Embodiment of Claim 14)
The embodiment of the fourteenth aspect is characterized in that only the main scanning magnification component is detected by the mark row.
By detecting only the main scanning magnification component from the mark row, it is possible to detect only components with large positional deviation fluctuations, reduce the processing load, and reduce the productivity by minimizing the calculation. it can.
Here, in the embodiments of the thirteenth and fourteenth aspects, the change in the main scanning magnification is abrupt and large among various misalignment components. This is because the lenses and mirrors in the exposure unit 8 are easily affected by temperature changes, causing changes in lens refractive index and mirror attitudes. Therefore, it is assumed that only magnification deviation is detected by a pattern formed between sheets. Thereby, it is possible to save the calculation processing by the CPU performed between the papers, and the print operation is not interrupted, so that the decrease in productivity can be minimized.

(Embodiment of Claim 15)
The embodiment of the fifteenth aspect is characterized in that only the sub-scanning resist component is detected by the mark row.
By detecting only the sub-scanning resist component from the mark row, it is possible to save the calculation and minimize the decrease in productivity.
In the embodiments of the fourteenth and fifteenth aspects, among various misalignment components, the change in the sub-scanning resist is abrupt and large as shown in FIG. This is because the lenses and mirrors in the exposure unit 8 are easily affected by temperature changes, causing changes in lens refractive index and mirror attitudes. Another reason is that the diameter of the driving roller 4 for driving the conveyor belt 2 changes depending on the temperature, the transfer speed changes, and the position shifts. Therefore, it is assumed that only the sub-scanning resist deviation is detected by the pattern formed between the sheets. In the case of the patterns in FIGS. 9 and 10, detection is possible only with the horizontal line. Thereby, it is possible to save the calculation processing by the CPU performed between the papers, and the print operation is not interrupted, so that the decrease in productivity can be minimized.

(Embodiment of claim 16)
The embodiment of the sixteenth aspect is characterized in that a main scanning resist component, a main scanning magnification component, and a sub-scanning resist component are detected from a mark row.
By detecting the main scanning resist component, the main scanning magnification component, and the sub-scanning resist component from the mark row, there is no detection of a skew component that does not actually exist, and the calculation processing can be saved by that amount.
Further, in the embodiment of the sixteenth aspect, among the various misalignment components, the skew misalignment has little change. This is because once the skew deviation is corrected, it occurs due to an inclination or the like when the photosensitive member 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 sheets. 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.

(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 transfer sheet conveyance direction.
Since the mark row pattern includes a line shape perpendicular to the transfer sheet conveyance direction, at least a shift component in the sub-scanning direction can be detected, and high image quality can be achieved.
In the embodiment of the seventeenth aspect, when detecting a shift in the sub-scanning direction, a line shape perpendicular to the transport direction must be included. 9 and 10 also include a line shape perpendicular to the transport direction.

(Embodiment of Claim 18)
According to an embodiment of the present invention, the detection sensor for detecting the mark row is made of an optical element and uses a change in specular reflection light or transmitted light amount. The pattern of the mark row is predetermined in the transfer direction of the transfer paper. An oblique line shape having an angle of
The detection sensor for detecting the mark row is composed of an optical element and uses a change in specular reflection light or transmitted light amount. The mark row pattern has an oblique line shape having a predetermined angle in the transfer paper transport direction. Therefore, at least a shift in the main scanning direction can be detected, and high image quality can be achieved.
In the embodiment of claim 18, when the detection sensors 14, 15, and 16 utilize changes in the amount of specularly reflected light or transmitted light from the belt surface, the magnification in the main scanning direction and the resist displacement are changed. In order to detect, the pattern to be formed must include an oblique line segment having a predetermined angle with respect to the transport direction as shown in FIGS. In the patterns in FIGS. 9 and 10, an oblique line having an angle of 45 ° with respect to the transport direction is used.

(Embodiment of Claim 19)
According to an embodiment of the present invention, the detection sensor for detecting the mark row is made of an optical element and uses a change in the amount of diffused light, and the pattern of the mark row is a line that is parallel or orthogonal to the transfer sheet conveyance direction. It includes a shape.
The detection sensor for detecting the mark row is composed of an optical element and uses a change in the amount of diffused light. Since the pattern of the mark row includes a line shape parallel to the transfer paper conveyance direction, at least a deviation in the main scanning direction is required. Can be detected, and image quality can be improved.
In the embodiment of claim 19, when the detection sensors 14, 15, and 16 utilize changes in the amount of diffused light on the belt surface, in order to detect the magnification in the main scanning direction and the registration deviation, 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 a misregistration detection mark row to which the color image forming method of the present invention is applied.
The misalignment detection mark rows are a plurality of rectangular reference patterns (five but not limited in the figure) formed on the conveying belt along the conveying direction and parallel to the conveying direction at a predetermined interval. And a comparison pattern that has the same shape as each reference pattern, has a different color, and is gradually shifted by a certain length in a direction perpendicular to the transport direction with respect to each reference pattern. ing.
For example, in the case of detecting a main scanning deviation of (C-BK) for a comparison pattern with a color C with respect to a reference pattern with a color BK, as shown in FIG. A shifted pattern is created (the first, second, third, fourth, and fifth stages from the top to the bottom of the figure). That is, in the first row, a comparison pattern having a size substantially equal to the reference pattern is arranged on the left side of the reference pattern, and in the second row, a comparison pattern having a width approximately half the width of the reference pattern is arranged on the left side of the reference pattern. In the fourth row, only the reference pattern is provided. In the fourth row, a 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 steps when the position deviation detection mark row shown in FIG. 5 is detected by a sensor. In FIG. 6, the horizontal axis indicates the number of pattern steps, and the vertical axis indicates the amount of diffused light (voltage value).
When these reference patterns and comparison patterns are formed on the transport belt, the diffused light reception amount (voltage value) changes as shown by the wavy line in the graph of FIG. This is because BK has a property of absorbing light, while the other colors C (Y, M) have a property of reflecting light.
However, when the misregistration detection mark row is formed on the transport belt, for example, the change in the diffused light reception amount (voltage value) when C is deviated in the negative direction becomes a solid line. In this case, the misregistration detection is performed. At the fourth stage of the mark row for use, the amount of received light is almost zero, that is, the most suitable state. In this way, if it is possible to know what stage the pattern having the smallest received light amount is, the correction amount can be determined.

FIG. 7 is a view showing a modification of the misalignment detection mark row to which the color image forming method of the present invention is applied.
The difference from the misalignment detection mark row shown in FIG. 5 is that both the reference pattern and the comparison pattern are in a direction orthogonal to the transport direction.
A plurality of misalignment detection mark rows shown in FIG. 7 are formed on the conveyor belt at a predetermined interval in the direction perpendicular to the conveyance direction along the conveyance direction (the number is five but is not limited in the figure). A rectangular reference pattern and a comparison pattern that has the same shape as each reference pattern, has a different color, and is gradually shifted by a certain length parallel to the transport direction with respect to each reference pattern. It consists of
Even if such a misregistration detection mark row is used, the same effect as the misregistration detection mark row shown in FIG. 5 can be obtained.

(Embodiment of claim 20)
According to an embodiment of the present invention, a latent image is formed on a photoreceptor by exposure, the latent image is developed to form an unfixed color image on a recording sheet, and a mark row for unfixed alignment is transferred to a transfer sheet. A color image forming method for correcting a misalignment of an unfixed color image by detecting and calculating a misregistration amount of a mark row, which is formed on an intermediate transfer member or an intermediate transfer member, based on an output from a sensor The transfer interval between transfer sheets is wider than a predetermined interval, and a plurality of mark rows are formed in the carry direction in the widened area of the transfer means or intermediate transfer member, and the mark rows are detected and the positional deviation correction is continuously printed. It is characterized by being performed inside.
By making the conveyance interval between transfer sheets wider than a predetermined interval and forming at least one mark row in the widened area of the conveyance means or the intermediate transfer member, 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 speed fluctuations in the carrying direction of the conveying means or intermediate transfer member (by taking the average of the mark row detection results). Therefore, the accuracy of positional deviation correction can be improved.

(Embodiment of Claim 22)
In the embodiment of the twenty-second aspect, the control means develops the latent image formed on the photosensitive member by exposure to form an unfixed color image, and transfers the unfixed color image to the intermediate transfer member. Then, transfer again to the transfer paper or transfer the unfixed color image directly to the transfer paper, Procedure C for transporting the recording paper to the transfer means, and make the transport interval between the transfer paper wider than a predetermined interval, It is characterized in that a procedure D for forming at least one mark row in a widened area of the conveying means or the intermediate transfer member, and a procedure E for detecting a mark row and performing positional deviation correction during continuous printing are executed.
By making the conveyance interval between transfer sheets wider than a predetermined interval and forming at least one mark row in the widened area of the conveyance means or the intermediate transfer member, 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 speed fluctuations in the carrying direction of the conveying means or intermediate transfer member (by taking the average of the mark row detection results). Therefore, the accuracy of positional deviation correction can be improved.

(Embodiment of Claim 24)
The embodiment of claim 24 is a recording medium, wherein the controller A develops the latent image formed on the photosensitive member by exposure to form an unfixed color image, After transferring to the intermediate transfer body, transfer again to the transfer paper or transfer the unfixed color image directly to the transfer paper, Procedure C for transferring the transfer paper to the transfer means, and the transfer interval between the transfer papers to a predetermined interval A program for executing the procedure D for forming at least one mark row in the widened area of the conveying means or the intermediate transfer member and the procedure E for detecting the mark row and correcting the misalignment during continuous printing. Characterized by recording.
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 conveyance interval between transfer sheets wider than a predetermined interval and forming at least one mark row in the widened area of the conveyance means or the intermediate transfer member, it is not necessary to stop the apparatus. By detecting the mark rows formed in the area between the transfer sheets, the influence of speed fluctuations in the transport direction of the transport means or intermediate transfer body can be canceled (by taking the average of the mark row detection results). Therefore, the accuracy of positional deviation correction can be improved.

(Other examples of the conveyor belt)
Up to this point, a method of forming a pattern and a patch on the conveying belt 2 and performing alignment has been described. However, the belt is not limited to this, and for example, an intermediate transfer belt can be similarly implemented. Further, the belt 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.

Incidentally, there is a demand from the industry to minimize the downtime due to the detection of misalignment during continuous printing.
In view of this, the present inventor has proposed a color image forming apparatus, a color image forming program, and a recording medium that can accurately perform misregistration correction even during continuous printing and can minimize downtime due to misregistration detection. .
(Embodiment of claim 2)
In this image forming method, a latent image is formed on a photosensitive member by exposure, the latent image is developed to form an unfixed color image on a recording sheet, and a mark row for unfixed alignment is recorded on a recording sheet conveying unit or A color image forming method for correcting misalignment of an unfixed color image by detecting and calculating the misregistration amount of a mark row formed on an intermediate transfer body, and based on the output from a sensor, During the continuous printing, a plurality of mark rows are formed in the carrying direction in the widened area of the conveying means or intermediate transfer member in the conveying direction, and the mark rows are detected and the positional deviation correction is performed. In addition, when the positional deviation correction is automatically performed, a mark row having a length shorter than the length of the mark row used when the correction is performed by an instruction from the user is used.
FIG. 11 is a diagram showing the position variation due to the driving of the conveyor 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 variation 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 includes four horizontal lines (lines in a direction perpendicular to the conveyance direction of the conveyance belt) of four colors K, Y, C, and M shown in FIG. 9 and four diagonal lines. The mark is a set, and the four sets are formed along the conveyance direction. Each of the four sets of mark rows 170 is adjusted to a position fluctuation phase caused by fluctuations in driving speed such as belt running in the sub-scanning direction (arrow 90 direction), and errors in pattern formation and detection are minimized as shown in FIG. It is formed in consideration of the phase so as to decrease. 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 misregistration of each color and to minimize downtime due to misregistration detection.
In the present embodiment, the length of the mark row 170 has been described as being four sets of marks. However, the present invention is not limited to this, and the length of the mark row 170 is equal to the length of the mark row 17. It should be shorter than the length of. Further, in the present embodiment, the case has been described where the mark shape of the mark row 170 is composed of a line in a direction orthogonal to the conveyance direction of the conveyance belt and an oblique line, but the present invention is not limited to this. However, if it is possible to detect misalignment, a diagonal line that rises to the right and a diagonal line that rises to the left may be combined, and a line perpendicular to the conveyance direction of the conveyance belt is parallel to the conveyance direction of the conveyance belt. A line may be combined, and the shape of the pattern constituting the mark itself is not limited to a straight line, and may be any of a wavy line, an ellipse, an ellipse, a polygon, and a circle.

(Embodiment of Claim 21)
According to an embodiment of the present invention, a latent image is formed on a photosensitive member by exposure, the latent image is developed to form an unfixed color image on a recording sheet, and an unfixed alignment mark row is formed on the recording sheet. A color image forming method for correcting a positional deviation of an unfixed color image by detecting and calculating a positional deviation amount of a mark row formed on a conveying unit or an intermediate transfer member, and based on an output from a sensor, The conveyance interval between recording papers is wider than the normal printing interval, multiple mark rows are formed in the conveyance direction on the widened area of the conveyance means or intermediate transfer member, and the mark rows are detected and positional deviation correction is performed continuously. When performing the correction of misalignment automatically during printing, a mark row having a length shorter than the length of the mark row used when the correction is performed according to an instruction from the user is used.
With this configuration, it is possible to form a high-quality image with little misregistration of each color and to minimize downtime due to misregistration detection.

(Embodiment of Claim 23)
According to an embodiment of the present invention, the control unit of the color image forming apparatus has a procedure A for developing the latent image formed on the photosensitive member by exposure to form an unfixed color image, After transferring to the transfer body, transfer again to the recording paper, or to transfer the unfixed color image directly to the recording paper, Procedure C for transferring the recording paper to the transfer means, and the transfer interval between the recording papers to a predetermined interval The procedure D for forming at least one mark row in a wider area of the conveying means or the intermediate transfer member and the mark row are detected and the misregistration correction is performed during continuous printing, and the misalignment correction is automatically performed. Is performed, the procedure F using a mark string having a shorter length than the mark string used when correction is performed in accordance with an instruction from the user is performed.
With this configuration, it is possible to form a high-quality image with little misregistration of each color and to minimize downtime due to misregistration detection.

(Embodiment of Claim 25)
According to an embodiment of the present invention, the control unit of the color image forming apparatus has a procedure A for developing the latent image formed on the photosensitive member by exposure to form an unfixed color image, After transferring to the transfer body, transfer again to the recording paper, or to transfer the unfixed color image directly to the recording paper, Procedure C for transferring the recording paper to the transfer means, and the transfer interval between the recording papers to a predetermined interval The procedure D for forming at least one mark row in a wider area of the conveying means or the intermediate transfer member and the mark row are detected and the misregistration correction is performed during continuous printing, and the misalignment correction is automatically performed. Is performed, a program for executing the procedure F using a mark string having a shorter length than the mark string used when correction is performed according to an instruction from the user is recorded.
With this configuration, it is possible to form a high-quality image with little misregistration of each color and to minimize downtime due to misregistration detection.
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.

3 is a flowchart showing an embodiment of a color image forming method of the present invention. 1 is a block diagram showing an embodiment of a color image forming apparatus to which a color image forming method of the present invention is applied. 6 is a timing chart when forming a pattern of a mark row for detecting misalignment during continuous printing. It is a figure showing the relation between the number of continuous prints and the amount of sub-scanning deviation with respect to BK. It is a figure which shows other embodiment of the mark row | line | column for position shift detection to which the color image forming method of this invention is applied. FIG. 6 is a diagram showing a relationship between the amount of diffused light and the number of pattern steps when the position deviation detection mark row shown in FIG. 5 is detected by a sensor. It is a figure which shows the modification of the misalignment detection mark row | line | column to which the color image forming method of this invention is applied. 1 is a configuration diagram of a color image forming apparatus called a tandem type in which image forming units are arranged along a conveyance belt. FIG. 9 is a diagram illustrating a part of a misregistration detection toner mark row 17 formed on the conveyance belt 2 illustrated in the color image forming apparatus of FIG. 8. FIG. 9 is a diagram illustrating a positional variation due to driving of the conveyance belt illustrated in the color image forming apparatus of FIG. 8. FIG. 9 is a diagram illustrating a positional variation due to driving of the conveyance belt illustrated in the color image forming apparatus of FIG. 8.

Explanation of symbols

14, 15, 16 Sensor 17, 170 Toner mark row for detecting displacement (mark row for detecting displacement, 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 amount control unit 31 Write control board 32 Motor 33 Motor drive circuit 34 Clutch drive circuit 100 Paper feed roller 110 Electromagnetic clutch

Claims (25)

A plurality of unfixed color image forming units that are arranged along the recording paper conveyance direction and that develop the latent image formed on the photoreceptor by exposure to form an unfixed color image;
Transfer means for transferring the unfixed color image to the recording paper after transferring it to an intermediate transfer member, or transferring the unfixed color image directly to the recording paper;
A color image forming apparatus comprising: a conveying unit that conveys the recording sheet to the transfer unit;
The conveyance interval between the recording sheets is made wider than a predetermined interval, and at least one mark row is formed in the widened area of the conveyance means or the intermediate transfer member. A color image forming apparatus comprising correction means for performing printing. A plurality of unfixed color image forming units that are arranged along the recording paper conveyance direction and that develop the latent image formed on the photoreceptor by exposure to form an unfixed color image;
Transfer means for transferring the unfixed color image to the recording paper after transferring it to an intermediate transfer member, or transferring the unfixed color image directly to the recording paper;
A color image forming apparatus comprising: a conveying unit that conveys the recording sheet to the transfer unit;
The conveyance interval between the recording sheets is made wider than a predetermined interval, and at least one mark row is formed in the widened area of the conveyance means or the intermediate transfer member. A color image forming apparatus using a mark row having a length shorter than that of a mark row used when correction is performed in accordance with an instruction from a user when performing the correction of misalignment automatically during printing. . The correction unit includes a conveyance interval adjusting unit that makes the conveyance interval between the recording sheets wider than the interval during normal printing and smaller than the length of the outer periphery of the photoconductor.
Mark row forming means for forming a mark row in a widened area of the conveying means or the intermediate transfer member;
A positioning sensor for detecting the mark row;
The color image forming apparatus according to claim 1, further comprising a control unit that performs misregistration correction of the unfixed color image during continuous printing by calculating based on an output from the sensor.   The transport unit includes a loop-shaped transport belt that transports the recording paper so that the unfixed image is transferred by the unfixed color image forming units, and a rotation drive unit that rotationally drives the transport belt. The color image forming apparatus according to claim 1, wherein the color image forming apparatus is a color image forming apparatus.   The intermediate transfer member includes a loop-shaped transfer belt to which an unfixed image and the mark from each of the unfixed color image forming portions are transferred, and a rotation driving unit that rotationally drives the transfer belt. The color image forming apparatus according to any one of claims 1 to 3.   The intermediate transfer body includes a transfer drum to which the unfixed color image and the mark from each of the unfixed color image forming portions are transferred, and a rotating unit that rotates the transfer drum. The color image forming apparatus according to any one of 1 to 3. The mark row forming means also serves as the unfixed color image forming unit so as to form an unfixed pattern of the mark row between the formation of the unfixed image.
The control unit delays the timing of forming the unfixed color image so as to form the mark row in the unfixed color image forming unit, and the length of the mark row in the transport direction by the transport interval adjusting unit. 7. The color image forming apparatus according to claim 1, wherein the timing of transporting the recording paper is delayed by an amount corresponding to the color image forming apparatus.   The color according to claim 1, wherein a length of the mark row along a conveyance direction of the recording paper is a length capable of detecting a positional shift with high accuracy. Image forming apparatus.   9. The correction unit according to claim 1, wherein the correction unit automatically performs correction every predetermined number of prints, or performs correction when an instruction from a user is given. Color image forming apparatus.   The color image forming apparatus according to claim 1, wherein the mark row has all colors of image forming colors.   10. The color according to claim 1, wherein the mark row has colors of two unfixed color image forming portions that are farthest among the unfixed color image forming portions. Image forming apparatus.   10. The color image formation according to claim 1, wherein the mark row has colors of two unfixed color image forming portions having the largest positional deviation among combinations of unfixed color images. apparatus.   13. The color image according to claim 10, wherein at least one of a main scanning resist component, a main scanning magnification component, a sub-scanning resist component, and a skew component is detected by the mark row. Forming equipment.   The color image forming apparatus according to claim 13, wherein only a main scanning magnification component is detected by the mark row.   14. The color image forming apparatus according to claim 13, wherein only the sub-scanning resist component is detected by the mark row.   14. The color image forming apparatus according to claim 13, wherein a main scanning resist component, a main scanning magnification component, and a sub-scanning resist component are detected from the mark row.   The color image forming apparatus according to claim 13, wherein the mark row pattern includes a line shape perpendicular to a conveyance direction of the recording paper.   The detection sensor for detecting the mark row is composed of an optical element, and utilizes a change in specular reflection light or transmitted light amount. The pattern of the mark row is a slant having a predetermined angle in the conveyance direction of the recording paper. The color image forming apparatus according to claim 13, comprising a line shape.   The detection sensor for detecting the mark row is formed of an optical element and utilizes a change in the amount of diffused light, and the pattern of the mark row includes a line shape that is parallel or orthogonal to the conveyance direction of the recording paper. The color image forming apparatus according to claim 13. A latent image is formed on the photosensitive member by exposure, the latent image is developed to form an unfixed color image on the recording paper, and an unfixed alignment mark row is formed on the recording paper conveying means or the intermediate transfer member. A color image forming method for correcting the positional deviation of the unfixed color image by forming, detecting and calculating a positional deviation amount of the mark row,
Based on the output from the sensor, the conveyance interval between the recording sheets is made wider than the normal print interval, and a plurality of mark rows are formed in the conveyance direction in the widened area of the conveyance means or the intermediate transfer member. A color image forming method, wherein the mark row is detected and misalignment correction is performed during continuous printing. A latent image is formed on the photosensitive member by exposure, the latent image is developed to form an unfixed color image on the recording paper, and an unfixed alignment mark row is formed on the recording paper conveying means or the intermediate transfer member. A color image forming method for correcting the positional deviation of the unfixed color image by forming, detecting and calculating a positional deviation amount of the mark row,
Based on the output from the sensor, the conveyance interval between the recording sheets is made wider than the normal print interval, and a plurality of mark rows are formed in the conveyance direction in the widened area of the conveyance means or the intermediate transfer member. When the mark row is detected and misalignment correction is performed during continuous printing, and the misalignment correction is automatically performed, the length of the mark row used when the correction is performed according to an instruction from the user is shorter. A color image forming method using a mark row.   The control unit of the color image forming apparatus develops the latent image formed on the photosensitive member by exposure to form an unfixed color image, and transfers the unfixed color image to the intermediate transfer member and then records the recording. Procedure B for retransferring to the paper or transferring the unfixed color image directly to the recording paper, Procedure C for transporting the recording paper to the transfer means, and a conveyance interval between the recording papers wider than a predetermined interval Then, a procedure D for forming at least one mark row in the widened area of the conveying means or the intermediate transfer member and a procedure E for detecting the mark row and performing positional deviation correction during continuous printing are executed. A featured color image forming program.   The control unit of the color image forming apparatus develops the latent image formed on the photosensitive member by exposure to form an unfixed color image, and transfers the unfixed color image to the intermediate transfer member and then records the recording. Procedure B for retransferring to the paper or transferring the unfixed color image directly to the recording paper, Procedure C for transporting the recording paper to the transfer means, and a conveyance interval between the recording papers wider than a predetermined interval The procedure D for forming at least one mark row in the widened area of the conveying means or the intermediate transfer member, and detecting the mark row and performing misalignment correction during continuous printing, and automatically misaligning When performing the correction, a color image formation is performed by executing the procedure F using a mark row having a length shorter than the length of the mark row used when the correction is performed according to an instruction from the user. Program.   The control unit of the color image forming apparatus develops the latent image formed on the photosensitive member by exposure to form an unfixed color image, and transfers the unfixed color image to the intermediate transfer member and then records the recording. Procedure B for retransferring to the paper or transferring the unfixed color image directly to the recording paper, Procedure C for transporting the recording paper to the transfer means, and a conveyance interval between the recording papers wider than a predetermined interval And a program for executing a procedure D for forming at least one mark row in the widened area of the conveying means or the intermediate transfer member and a procedure E for detecting the mark row and performing positional deviation correction during continuous printing. A recording medium characterized by recording.   The control unit of the color image forming apparatus develops the latent image formed on the photosensitive member by exposure to form an unfixed color image, and transfers the unfixed color image to the intermediate transfer member and then records the recording. Procedure B for retransferring to the paper or transferring the unfixed color image directly to the recording paper, Procedure C for transporting the recording paper to the transfer means, and a conveyance interval between the recording papers wider than a predetermined interval The procedure D for forming at least one mark row in the widened area of the conveying means or the intermediate transfer member, and detecting the mark row and performing misalignment correction during continuous printing, and automatically misaligning When the correction is performed, a program for executing the procedure F using the mark string having a shorter length than the mark string used when the correction is performed according to an instruction from the user is recorded. Recording medium.

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