JP4869692B2 - Image forming apparatus, color misregistration correction method, and color misregistration correction program - Google Patents

Description

  According to the present invention, a color misregistration caused by an image forming unit is formed when an image of a plurality of colors is formed on an image carrier and the image formed on the image carrier is transferred to a paper medium to form an image. The present invention relates to an image forming apparatus capable of correcting, a color misregistration correction method, and a color misregistration correction program.

  Conventionally, as a dandem type color image forming apparatus, yellow (Y), magenta (M), cyan (C), and black (K) are provided for each color by a writing unit (image forming unit), and the writing unit generates A full color image is efficiently formed by sequentially superimposing and forming color images of different colors on an image carrier such as an intermediate transfer belt, and transferring the color image formed on the image carrier onto a transfer medium. Is generally known.

  In this dandem type color image forming apparatus, when an image generated by a different writing unit for each color is transferred to the intermediate transfer belt, the color is slightly shifted in the sub-scanning direction, for example, the paper transport direction, that is, So-called color misregistration occurs in which the pixel positions of the respective color sensations are shifted from each other.

  Therefore, a technique for forming a specific correction pattern image in two rows in the sub-scanning direction on the intermediate transfer belt before image formation and performing correction processing to suppress the occurrence of color misregistration of each color using the correction pattern image. It has been known.

  As one of the causes of such color misregistration, a mechanical attachment error of the writing unit is considered. For example, as shown in FIG. 8, when the writing unit is attached to the correct attachment position (801a) with an error of θ (801b), skew deviation (due to the scanning line inclination) that is an error caused by the attachment error. Color misregistration) occurs. Even if a correction process is performed by forming a specific correction pattern on the transfer belt while leaving the skew deviation, the registration deviation cannot be completely corrected.

  That is, when the writing unit is mounted in a state in which the skew deviation does not occur completely, the correction patterns of the black (K) writing unit and the magenta (M) writing unit formed by the two rows of correction patterns. The intervals a and b have the same value (a = b). However, when an attachment error occurs during attachment of the writing unit and skew deviation occurs, one of the correction pattern of the black (K) writing unit and the correction pattern of the magenta (M) writing unit, as shown in FIG. (814a, 814b) has a shift of α from the theoretical value pattern, and the other correction pattern (814c, 814d) is formed to have a shift of β from the theoretical value pattern, and the pattern intervals are not the same ( a ≠ b).

  Therefore, in such a case, registration correction is performed by calculating (α + β) / 2, which is an average value of both, as a correction amount. In this case, the correction is only performed using the average value, and when the skew shift occurs, the registration shift cannot be completely corrected. That is, α-((α + β) / 2) and β-((α + β) / 2) remain, and the remaining displacement cannot be corrected.

  Therefore, in the correction control by the first correction pattern formation, control for correcting only the skew deviation is performed. Subsequently, the correction control by the second correction pattern formation is performed, and in the second correction control, only the registration deviation is corrected. A technique for performing control has been developed (see, for example, Patent Document 1). Thus, since the registration error is corrected after the skew error is eliminated, the registration error due to the skew error can be corrected with high accuracy.

Japanese Patent No. 3351435

  However, in such a conventional technique, it is necessary to form a correction pattern twice on the transfer belt, calculate a correction amount, and perform correction control. For this reason, there is a problem that the time required for the correction process increases. In view of this, it is conceivable to perform a process of correcting the skew deviation and the registration deviation simultaneously by forming the correction pattern once.

  However, in the correction process that corrects skew deviation and registration deviation at the same time using only one correction pattern, the registration process is performed after the skew correction result is completely reflected, compared with the case where correction is performed by forming the correction pattern twice. Since the deviation is not corrected, there is a problem that the accuracy of correcting the registration deviation is lowered when the skew deviation is large.

  The present invention has been made in view of the above, and an object thereof is to provide an image forming apparatus, a color misregistration correction method, and a color misregistration correction program capable of performing color misregistration correction with high accuracy in a short time. .

In order to solve the above-described problems and achieve the object, an image forming apparatus according to the present invention includes:
An image forming apparatus that includes an image forming unit that superimposes and forms an image of a plurality of colors on an image carrier, and that forms an image by transferring the image formed on the image carrier to a paper medium. Pattern forming means for forming a correction pattern for correcting misregistration of each color on the carrier, detection means for detecting the correction pattern formed on the image carrier, and the correction pattern detected by the detection means A correction amount calculating unit that calculates a color misregistration amount due to a scanning line inclination of the image forming unit and a color misregistration amount other than the scanning line inclination, and calculates a correction amount for correcting each obtained color misregistration amount; Control means for controlling the image forming unit based on the correction amount calculated by the correction amount calculating means; and a current time after a predetermined first time has elapsed since the previous correction processing execution, 1 hour Before the lapse of a longer second time, the number of color misregistration correction processes, which is a series of processes of the pattern forming means, the detecting means, the correction amount calculating means, and the control means, is determined as one, and the current time is When the second time has elapsed since the previous correction processing execution, the number of times is determined as a plurality of times, and the color misalignment correction processing is executed for the determined number of times. And a determination processing means for controlling the correction amount calculation means and the control means.

In addition, the color misregistration correction method according to the present invention includes an image forming unit that forms a plurality of color images on an image carrier, and transfers the image formed on the image carrier to a paper medium. A color misregistration correction method executed by an image forming apparatus that performs formation, wherein a pattern forming unit forms a correction pattern for correcting misregistration of each color on the image carrier, and a detection unit includes: A detection step of detecting the correction pattern formed on the image carrier, and a correction amount calculation means, based on the correction pattern detected by the detection step, a color shift caused by a scanning line inclination of the image forming unit A correction amount calculating step of calculating a correction amount for correcting each of the obtained color misregistration amounts, and a correction means calculating the correction amount calculated by the correction amount calculating step. And a determination processing unit that controls the image forming unit based on the second time after the predetermined first time has elapsed since the previous correction processing execution and is longer than the first time. Before the lapse of time, the number of color misregistration correction processes, which is a series of processes of the pattern forming means, the detecting means, the correction amount calculating means, and the control means, is determined as one, and the current time is the previous correction process execution. When the second time has elapsed from the time, the number of times is determined as a plurality of times, and the color misalignment correction processing is executed for the determined number of times, and the pattern forming unit, the detecting unit, and the correction amount calculation And a determination processing step for controlling the control means.

The program according to the present invention further includes an image forming unit that forms and superimposes images of a plurality of colors on an image carrier, and performs image formation by transferring the image formed on the image carrier to a paper medium. A program for causing a computer to execute, a pattern forming step for forming a correction pattern for correcting misregistration of each color on the image carrier, and detection for detecting the correction pattern formed on the image carrier And a color misregistration amount due to the scanning line tilt of the image forming unit and a color misregistration amount other than the scan line tilt are obtained based on the correction pattern detected by the process and the detection step, and the obtained color misregistration amounts are corrected. A correction amount calculating step for calculating a correction amount for controlling the image forming unit based on the correction amount calculated by the correction amount calculating step; A series of the pattern formation step, the detection step, the correction amount calculation step, and the control step after a lapse of a predetermined first time from the execution of the correction process and before a lapse of a second time longer than the first time. The number of times of color misregistration correction processing is determined as one, and if the current time is after the second time has elapsed since the previous correction processing execution, the number of times is determined as a plurality of times and determined. A judgment processing step for controlling the pattern formation step, the detection step, the correction amount calculation step, and the control step so as to execute the color misregistration correction processing as many times as possible;
Is executed by the computer.

  According to the present invention, the number of color misregistration correction processes is determined based on a predetermined condition, and the color misregistration correction process is executed with the determined number of times, so that highly accurate color misregistration correction can be performed in a short time. There is an effect.

  Exemplary embodiments of an image forming apparatus, a color misregistration correction method, and a color misregistration correction program according to the present invention will be explained below in detail with reference to the accompanying drawings. In the embodiment described below, an example in which the image forming apparatus of the present invention is applied to a multi-function machine in which functions of a printer, a facsimile, a copy, and a scanner are housed in one housing will be described.

(Embodiment 1)
FIG. 1 is a front view of an image forming unit, a writing unit, and a transfer belt for explaining the image forming principle of a color multifunction peripheral.

  In the MFP according to the first embodiment, the image forming unit 1 includes four image forming units 1Y, 1M, and 1M that form images of different colors (yellow: Y, magenta: M, cyan: C, black: K). 1C and 1K are dandem type systems arranged in a line along a transfer belt 3 that conveys a transfer sheet 2 as a transfer medium. The transfer belt 3 is provided between a driving roller 4 that rotates and a driven roller 5 that rotates and is driven to rotate in the direction of the arrow in FIG. A paper feed tray 6 in which the transfer paper 2 is stored is provided below the transfer belt 3. The transfer sheet 2 at the uppermost position among the transfer sheets 2 stored in the sheet feed tray 6 is fed toward the transfer belt 3 during image formation, and is attracted onto the transfer belt 3 by electrostatic adsorption. The adsorbed transfer sheet 2 is conveyed to the yellow image forming unit 1Y, where yellow image formation is performed.

  Each of the image forming units 1Y, 1M, 1C, and 1M includes photosensitive drums 7Y, 7M, 7C, and 7K, and chargers 8Y, 8M, and 8C disposed around the photosensitive drums 7Y, 7M, 7C, and 7K, respectively. , 8K, developing devices 10Y, 10M, 10C, 10K and photoreceptor cleaners 11Y, 11M, 11C, 11K.

  An exposure unit (writing unit) 9 is disposed above the image forming unit 1, and this writing unit 9 forms a laser beam for forming an electrostatic latent image of each color on each photosensitive drum 7Y, 7M, 7C, 7K. Four laser beam scanning devices (LD) corresponding to the respective colors that irradiate LY, LM, LC, and LK, four LD control units that control the laser beam irradiation by each laser beam scanning device (LD), and 3 One skew correction motor is provided (none of which are shown in FIG. 1, see FIG. 3).

  Here, the image forming unit 1 and the writing unit 9 constitute an image forming unit. The surface of the photosensitive drum 7Y of the image forming unit is uniformly charged by the charger 8Y, and then exposed by the writing unit 9 with the laser beam LY corresponding to the yellow image, thereby forming an electrostatic latent image. The formed electrostatic latent image is developed by the developing device 10Y, and a toner image is formed on the photosensitive drum. This toner image is transferred to the transfer paper 2 by the transfer device 12Y at a position (transfer position) where the photosensitive drum 7Y and the transfer paper 2 on the transfer belt 3 are in contact with each other. ) Is formed. In the photoreceptor drum 7Y after the transfer, unnecessary toner remaining on the drum surface is cleaned by the photoreceptor cleaner 11Y to prepare for the next image formation.

  In this way, the transfer sheet 2 on which the single color (yellow) is transferred by the yellow image forming unit 1Y is conveyed by the transfer belt 3 to the magenta image forming unit 1M. Similarly, the toner image (magenta) formed on the photosensitive drum 7M is transferred onto the transfer paper 2 in a similar manner. The transfer paper 2 is further conveyed to the cyan image forming unit 1C and the black image forming unit 1K in order, and similarly, the formed toner image is transferred to the transfer paper 2 and thereby transferred onto the transfer paper 2. A color image is formed.

  Then, the transfer paper 2 on which the color image is formed by passing through the black image forming unit 1K is peeled off from the transfer belt 3, fixed by the fixing device 13, and then discharged.

  In the tandem type color multifunction peripheral according to the first embodiment shown in FIG. 1, the alignment technique between the colors becomes an important issue because of its configuration. There are mainly the following five components as color misregistration components of each color.

(1) Skew deviation which is color deviation caused by angular deviation (scanning line inclination) in the scanning direction of the writing unit 9, and (2) Movement direction of the transfer belt 3, that is, the writing unit 9 in the sub scanning direction to the photosensitive member. Registration shift in the sub-scanning direction, which is a color shift caused by a shift in writing timing, (3) Pitch unevenness in the sub-scanning direction, and (4) Scanning direction of the writing unit 9, that is, the photoconductor by the writing unit 9 in the main scanning direction. Registration error in the main scanning direction, which is a color shift caused by a shift in writing timing, and (5) a magnification error in the main scanning direction due to expansion / contraction of the image in the main scanning direction.

  In the multi function device of the first embodiment, in order to control the drive of the writing unit 9 so as to detect the color deviation due to the skew deviations (1) to (5) and the color deviation caused by other than the skew, Prior to the forming operation, positional deviation correction for each color is performed.

  FIG. 2 is a perspective view of the transfer belt 3 showing a state in which the correction pattern 14 is formed on the transfer belt 3. In the MFP according to the first embodiment, for such color misregistration correction, first, a correction pattern 14 for color misregistration correction of each color is formed on the transfer belt 3 by the writing unit 9, and the correction pattern 14 is set to 2 Two detection sensors 15 and 16 are used for detection. In the first embodiment, as shown in FIG. 2, two detection sensors 15 and 16 are arranged at both ends of the transfer belt 3 in the main scanning direction, and the arrangement positions of the detection sensors 15 and 16 are arranged on the transfer belt 3. The correction pattern 14 is formed corresponding to the above. Such a correction pattern 14 is detected when the transfer belt 3 rolls and passes through the detection sensors 15 and 16 in order.

  FIG. 3 is a block diagram illustrating a configuration of a mechanism that performs color misregistration correction of the multifunction peripheral according to the first embodiment. In the MFP according to the first embodiment, the two detection sensors 15 and 16, the pattern detection unit 19, the correction amount calculation unit 20, the determination processing unit 31, and the memory 21 are described for color misregistration correction. And a write control unit 22 and a skew correction motor control unit 23, and the write control unit 22 and the skew correction motor control unit 23 are connected to the write unit 9.

  The detection sensors 15 and 16 detect the position of the correction pattern 14 formed on the transfer belt 3 and output an analog detection signal. The pattern detection unit 19 amplifies the detection signals output from the detection sensors 15 and 16, converts the amplified analog detection signal into digital data, and stores the digital data in the memory 21.

  The correction amount calculation unit 20 calculates a color misregistration amount from the digital data of the detection signal at the position of the correction pattern 14 stored in the memory 21, and calculates a correction amount for correcting the color misregistration amount from the color misregistration amount. It is a processing unit. Here, the color misregistration amount includes a skew misalignment amount, a main scanning direction registration misalignment amount, a sub scanning direction registration misalignment amount, a sub scanning direction pitch unevenness amount, and a main scanning direction magnification error amount. As the correction amount, a skew correction amount, a main scanning direction registration correction amount, a sub scanning direction registration correction amount, a sub scanning direction pitch correction amount, and a magnification error correction amount are calculated from these various amounts. That is, in the first embodiment, the correction amount calculation unit 20 obtains the color misregistration amount due to skew and the color misregistration amount other than skew from the detection of the correction pattern 14 once, and the skew correction amount and the color misregistration correction amount other than skew. Is calculated.

  The writing control unit 22 is connected to the LD control units 24, 25, 26, and 27 in the writing unit 9, and the main scanning direction registration correction amount and the sub scanning direction registration correction calculated by the correction amount calculation unit 20. A correction write command is sent to the LD control units 24, 25, 26, and 27 of the writing unit 9 in accordance with the amount, and control for correcting a write timing shift caused by laser light irradiation is performed. The writing control unit 22 sends an image frequency change command corresponding to the magnification error correction amount calculated by the correction amount calculating unit 20 to the LD control units 24, 25, 26, and 27 of the writing unit 9, and performs main scanning. Performs correction control of direction magnification error. Further, the writing control unit 22 sends out a command for forming a correction pattern on the transfer belt 3 to the writing unit 9. The write control unit 22 controls the main scanning direction registration and the main scanning direction registration, and a device that can set the output frequency very finely, for example, a clock generator using a voltage controlled oscillator (VCO). It is prepared for each color.

  The skew correction motor control unit 23 is connected to the skew correction motors 28, 29, and 30 in the writing unit 9, and issues a correction write command to the writing unit 9 according to the skew correction amount calculated by the correction amount calculation unit 20. Sending out and performing drive control of each skew correction motor 28,29,30.

  Here, each color misregistration correction operation will be briefly described. The skew correction is performed by changing the inclination of a mirror (not shown) for turning back each color laser beam inside the writing unit 9. For example, a stepping motor is used as a drive source for biasing the mirror to change the tilt of the mirror.

  Sub-scanning direction registration correction is performed by activating an image area signal (write enable signal) in the sub-scanning direction by shifting the timing of the synchronization detection signal. For example, as a result of detecting the correction pattern 14 and performing a predetermined calculation, when performing color misregistration correction by increasing the writing start position by 1 dot, color misregistration is activated by activating the write enable signal one time earlier. Make corrections.

  As the image writing clock in the main scanning direction, a clock whose phase is accurately matched to each line is obtained by the falling edge of the synchronization detection signal, and image writing is performed in synchronization with this clock signal. The image write enable signal in the main scanning direction is also generated in synchronization with this clock. Therefore, the registration correction in the sub-scanning direction is performed by activating the image writing enable signal in the main scanning direction while shifting the clock. For example, as a result of detecting the correction pattern 14 and performing a predetermined calculation, when performing color misregistration correction by accelerating the 1-dot writing position, color misregistration correction is performed by activating the write enable signal earlier by one clock.

  For magnification correction in the main scanning direction, when the correction pattern 14 is detected and a predetermined calculation is performed, if the magnification in the main scanning direction is deviated from the reference color (one color in the correction pattern), the frequency is The magnification is changed by changing the frequency with a device such as a clock generator that can be changed in small steps.

  As described above, the multifunction peripheral according to the first embodiment performs both skew correction and color misregistration correction other than skew correction in one color misregistration correction process.

  The determination processing unit 31 forms the correction pattern 14 by the writing unit 9, detects the correction pattern 14 by the detection sensors 15 and 16, and detects the correction pattern 14 by the pattern detection unit 19 in accordance with various conditions such as environmental conditions and operation conditions of the multifunction device. A series of color shifts from detection signal processing of the correction pattern 14, calculation of each color shift amount by the correction amount calculation unit 20, calculation of each color shift correction amount, and drive control of the writing unit 9 according to various correction amounts by the write control unit 22. This is a processing unit that determines the number of times to perform the correction process and controls the above units to execute the color misregistration correction process for the determined number of times.

  In the color misregistration correction process, if the skew correction amount is large and the skew correction is performed, the skew correction can be performed completely, but there is also a slight shift in the main scanning magnification, main scanning direction registration, and sub-scanning direction registration. Will occur. For this reason, in the conventional misregistration correction processing, skew correction and correction other than skew are separately performed, and after correcting the skew, a correction pattern is formed again on the transfer belt 3 to perform color misregistration correction other than skew correction. I was going. Conventionally, color misregistration correction is divided into a plurality of modes, and color misregistration correction is executed in a mode in which skew correction is not performed during execution of a print job (during printing processing). Misalignment correction could not be performed.

  FIG. 4 is an explanatory diagram showing the relationship between the number of corrections and the correction accuracy. As shown in FIG. 4, the skew correction is corrected with high accuracy by the first correction processing. However, in the case of registration correction, correction cannot be performed with high accuracy only by the first correction processing.

  For this reason, in the MFP according to the first embodiment, the determination processing unit 31 determines that the number of corrections is 2 at the time of power-on when there is a possibility that a large skew deviation occurs as an operation condition of the MFP. Control to perform the color misregistration correction process twice. As a result, even if a slight shift occurs in the main scanning magnification, the main scanning direction registration, and the sub-scanning direction registration due to the skew correction in the first color misregistration correction process, the correction is performed by the second color misregistration correction process. Therefore, the accuracy of color misregistration correction can be further improved.

  On the other hand, the determination processing unit 31 determines that the number of corrections is set to 1 during the printing process and that the number of corrections is set to 1 immediately before the printing process, and performs control to correct the color misregistration only once. . For this reason, even if a slight skew deviation occurs during the printing process, it is possible to correct the minute skew deviation while keeping the time necessary for the color deviation correction executed by interruption during the execution of the print job in a short time. Therefore, highly accurate color misregistration correction can be realized without greatly affecting the printing processing time.

  Here, the determination processing unit 31 determines that the print job data is immediately before being received from the information processing apparatus or the like connected to the network, or if it is within a predetermined time since it is received, immediately before the print processing. And

  In addition, the determination processing unit 31 sets the current time as the environmental condition of the multifunction device twice after a predetermined time has elapsed since the previous correction process, and the current temperature changes more than a predetermined temperature from the temperature at the previous correction process. If the current number of printed sheets is equal to or more than a predetermined number from the end of the previous correction process, the number of times is determined to be two. Note that the time and temperature at the time of the previous correction process are stored and held in the memory 21 or the like, and are compared with the current time and temperature. Also, the number of printed sheets is stored in the memory 21 or the like at the end of the previous printing process, and is determined to be a predetermined number.

  Here, in the judgment processing unit 31, as the first condition after turning on the multifunctional machine as the environmental condition, the predetermined condition A1 has elapsed, the temperature has changed by a predetermined temperature B1 or more, or the number of printed sheets is C1 or more. Whether or not to perform the first color misregistration correction is determined, and further, as a second condition regardless of power-on, there is a temperature change after a predetermined time A2 or a predetermined temperature B2 or more. Whether or not the number of prints is equal to or greater than C3, and whether or not to perform color misregistration correction multiple times is determined. Note that A1 <A2, B1 <B2, and C1 <C2.

  When the second condition is satisfied, it is expected that the skew deviation is large. If color deviation correction is performed in such a case, as described above, skew correction can be performed completely, There may be slight deviations in scanning magnification, registration in the main scanning direction, and registration in the sub-scanning direction. Therefore, the determination processing unit 31 determines that the color misregistration correction is performed twice when the second condition is satisfied.

  In addition, the determination processing unit 31 may be configured to detect the opening / closing of the cover of the multifunction peripheral and determine the number of color misregistration corrections as a plurality of times when the cover is opened / closed. When the cover is opened and closed, the photoconductor may be replaced, and a large skew may occur at this time. Therefore, it may be caused by the first skew correction by performing multiple color misalignment correction processes. It is possible to completely correct the main scanning magnification error, the main scanning direction registration deviation, and the sub-scanning direction registration deviation to realize more accurate color misregistration correction. The second condition may be configured to be set and changed by a user input from the operation panel. In this case, it is possible to prevent the second and subsequent color misregistration corrections from being executed by changing the second condition as necessary.

  Further, the determination processing unit 31 is configured to determine the number of color misregistration corrections as a plurality of times at the end of the printing process that may cause a large skew misalignment in order to perform more accurate color misregistration correction. May be.

  In the first embodiment, the determination processing unit 31 determines whether the correction processing is performed once or twice. However, the determination processing unit 31 is configured to determine whether the correction processing is performed once or three times or more. May be.

  Next, the entire process of color misregistration correction by the multi-function peripheral according to Embodiment 1 configured as described above will be described. FIG. 5 is a flowchart of an overall process procedure of color misregistration correction performed by the multifunction peripheral according to the first embodiment.

  First, the determination processing unit 31 determines whether or not the current time is when the multifunction device is turned on (step S501). If the current time is when the power is turned on (step S501: Yes), the correction number N is calculated. Two times are determined (step S506).

  On the other hand, when the power is not turned on (step S501: No), the determination processing unit 31 determines whether the elapsed time from the previous correction process is longer than A1 or the previous correction as the first condition of the correction process. It is determined whether the current temperature change from the temperature at the time of processing is greater than B1, or whether the number of printed sheets from the end of the previous color misregistration correction is greater than C1 (step S502). Here, the time, temperature, and number of printed sheets at the time of the previous correction process are acquired from the memory 21. For example, A1 is 300 minutes and B1 is 5 ° C.

  If the first condition is not satisfied, that is, the elapsed time from the previous correction process is A1 or less, the current temperature change from the temperature at the previous correction process is B1 or less, and the previous time If the number of printed sheets after the end of color misregistration correction is C1 or less (step S502: No), the printing process is executed without performing the correction process (step S509).

  On the other hand, when the first condition is satisfied in step S502, that is, the elapsed time from the previous correction process is longer than A1, or the current temperature change from the temperature at the previous correction process is larger than B1. Alternatively, when the number of printed sheets from the end of the previous color misregistration correction is larger than C1 (step S502: Yes), the determination processing unit 31 further checks whether printing is currently being performed (step S503).

  When printing is in progress (step S503: Yes), the determination processing unit 31 determines the correction count N as 1 in order to quickly complete the printing process (step S507). On the other hand, if it is determined that printing is not being performed (step S503: No), the determination processing unit 31 checks whether or not the current time point is immediately before printing, which is immediately after reception of print job data (step S503). S504). If it is immediately before printing (step S504: Yes), the determination processing unit 31 determines the correction count N to be 1 in order to quickly start the printing process (step S507).

  On the other hand, if it is determined that it is not immediately before printing (step S504: No), the determination processing unit 31 determines that the elapsed time from the previous correction process is longer than A2 as the second condition of the correction process, or It is determined whether the current temperature change from the temperature at the previous correction process is greater than B2 or the number of printed sheets from the end of the previous color misregistration correction is greater than C2 (step S505). Here, for example, A2 is 600 minutes and B2 is 10 ° C.

  If the second condition is not satisfied, that is, the elapsed time from the previous correction process is A2 or less, the current temperature change from the temperature at the previous correction process is B2 or less, and the number of printed sheets Is equal to or less than C2 (step S505: No), the determination processing unit 31 determines the correction count N to be 1 (step S507).

  On the other hand, if the second condition is satisfied in step S505, that is, the elapsed time from the previous correction process is longer than A2, or the current temperature change from the temperature at the previous correction process is larger than B2. Alternatively, when the number of printed sheets is greater than C2 (step S505: Yes), the determination processing unit 31 determines that there is a high possibility that a large color shift has occurred, and determines the correction count N as 2 ( Step S506).

  Next, the determination processing unit 31 controls the detection sensors 15 and 16, the pattern detection unit 19, the correction amount calculation unit 20, the writing control unit 22, and the skew correction motor control unit 23 to determine the number of times determined in step S <b> 506 or S <b> 507. Color misregistration correction processing is executed for N minutes (step S508). Thus, the color misregistration correction process is executed twice when the power is turned on, once before printing and once during printing, and twice when the second condition is satisfied. Thereafter, a printing process is executed (step S509), and the number of printed sheets at this time is counted and stored in the memory 21 (step S510). As described above, the color misregistration correction process is performed once or twice depending on the operating condition and environmental condition of the multifunction peripheral.

  Next, specific processing for color misregistration correction in step S508 will be described. FIG. 6 is a flowchart showing a specific processing procedure for color misregistration correction. First, a correction pattern is formed on the transfer belt 3 by the writing unit 9 according to a command from the writing control unit 22 (step S601).

  Next, the transfer belt 3 is driven, and correction pattern detection is performed such as detection of a correction pattern by the detection sensors 15 and 16 and acquisition of a detection signal by the pattern detection unit 19 (step S602). As a result, since the sampled digital data of the detection signal of the correction pattern 14 is stored in the memory 21, the digital data is read from the memory 21 by the correction amount calculation unit 20, and the main scanning magnification error amount and the main scanning direction registration are read out. The amount of misregistration, the amount of misregistration in the sub-scanning direction, and the amount of skew misalignment are calculated, and the main scanning magnification correction amount, the main scanning direction registration correction amount, and the sub-scanning direction registration correction amount (main sub-registration correction amount) Correction amount) and skew deviation amount are calculated (step S603).

  Here, if the main scanning magnification is corrected by the calculated main scanning magnification correction amount, a slight shift also occurs in the registration in the main scanning direction. For this reason, in the main scanning direction registration correction amount calculation process, a main scanning direction registration shift amount that occurs when the main scanning magnification is changed by main scanning magnification correction is predicted, and the detection from the predicted amount and the correction pattern 14 is detected. The main-scanning direction registration correction amount is calculated together with the actual main-scanning direction registration deviation amount calculated from the result.

  Then, main scanning magnification correction based on the main scanning magnification correction amount is executed by the writing control unit 22 and the LD control units 24-27 of the writing unit 9 (step S604). Next, the writing control unit 22 and the LD control units 24 to 27 of the writing unit 9 execute main scanning direction registration correction and sub scanning direction registration correction (main / sub registration correction) based on the main / sub resist correction amount (step) S605).

  Next, skew correction is performed by the skew correction motor control unit 23 and the skew correction motors 28, 29, and 30 of the writing unit 9 (step S606). Thus, one color misregistration correction process is completed.

  As described above, in the multifunction peripheral according to the first embodiment, the determination processing unit 31 determines the number of color misregistration correction processes according to the operating conditions and environmental conditions of the multifunction peripheral, and executes the determined number of color misregistration correction processes. Therefore, it is possible to perform highly accurate color misregistration correction in a short time without affecting the other color misregistration correction due to skew correction.

  In addition, since the color misregistration correction process is executed only immediately before the printing process or during the printing process, it does not affect the printing process time while correcting for a slight skew deviation, so it can be performed in a short time. Accurate color misregistration correction can be performed.

(Embodiment 2)
The MFP according to the first embodiment determines the number of color misregistration corrections according to the operating conditions and environmental conditions of the MFP. However, the MFP according to the second embodiment uses the previous color misregistration correction. The number of color misregistration corrections is determined according to the result.

  The configuration of the image forming unit, the writing unit, and the transfer belt of the multifunction device according to the second embodiment, the state of the transfer belt on which the correction pattern is formed, and the configuration of the mechanism that performs color misregistration correction of the multifunction device are illustrated in FIGS. This is the same as the MFP according to the first embodiment described in (3) and (3).

  In the MFP according to the second embodiment, the determination processing unit 31 further determines the number of color misregistration corrections based on the result of the previous color misregistration correction process. Specifically, the determination processing unit 31 performs the color misregistration correction process once more when the skew correction amount is larger than the predetermined amount D in the previous color misregistration correction process. The pattern detection unit 19, the correction amount calculation unit 20, the write control unit 22, and the skew correction motor control unit 23 are controlled. That is, in the previous color misregistration correction process, when the skew correction amount is equal to or smaller than the predetermined amount D, it is considered that the effect of the skew correction on the other color misregistration correction is very small. Sufficiently high-precision correction can be performed, and unnecessary color misregistration correction processing two or more times is omitted to shorten the time of color misregistration correction processing.

  Next, the overall process of color misregistration correction by the multifunction peripheral according to the second embodiment will be described. FIG. 7 is a flowchart of an overall process procedure of color misregistration correction by the multifunction peripheral according to the second embodiment. First, as a first condition for the correction process, the determination processing unit 31 has an elapsed time from the previous correction process longer than A1, or a change in the current temperature from the temperature at the previous correction process is larger than B1. Alternatively, it is determined whether the number of printed sheets from the end of the previous color misregistration correction is greater than C1 (step S701). Here, prior to the processing in step S701, the number of corrections may be determined by determining whether or not the current time is when the power is turned on, as in the first embodiment.

  If the first condition is not satisfied, that is, the elapsed time from the previous correction process is A1 or less, the current temperature change from the temperature at the previous correction process is B1 or less, and the previous color When the number of printed sheets after the end of the deviation correction is C1 or less (step S701: No), the printing process is executed without performing the correction process (step S708).

  On the other hand, when the first condition is satisfied in step S701, that is, the elapsed time from the previous correction process is longer than A1, or the current temperature change from the temperature at the previous correction process is larger than B1. Alternatively, when the number of printed sheets from the end of the previous color misregistration correction is greater than C1 (step S701: Yes), the determination processing unit 31 further checks whether printing is currently being performed (step S702).

  When printing is in progress (step S702: Yes), the determination processing unit 31 determines the number of corrections to be 1 in order to quickly complete the printing process. Then, the detection sensors 15 and 16, the pattern detection unit 19, the correction amount calculation unit 20, the writing control unit 22, and the skew correction motor control unit 23 are controlled to execute the color misregistration correction process only once (step S 707). Print processing is executed (step S708).

  On the other hand, if it is determined in step S702 that printing is not being performed (step S702: No), the determination processing unit 31 determines whether or not the current time point is immediately before printing, which is immediately after receiving print job data. (Step S703). If it is immediately before printing (step S703: Yes), the determination processing unit 31 determines the number of corrections to be one in order to quickly start the printing process. Then, the detection sensors 15 and 16, the pattern detection unit 19, the correction amount calculation unit 20, the writing control unit 22, and the skew correction motor control unit 23 are controlled to execute the color misregistration correction process only once (step S 707). Print processing is executed (step S708).

  On the other hand, if it is determined in step S703 that it is not immediately before printing (step S703: No), the color misregistration correction process is executed once (step S704).

  As a second condition for the correction process, the determination processing unit 31 determines whether the elapsed time from the previous correction process is longer than A2, or whether the current temperature change from the temperature at the previous correction process is greater than B2. Alternatively, it is determined whether the number of printed sheets from the end of the previous color misregistration correction is greater than C2 (step S705).

  If the second condition is not satisfied, that is, the elapsed time from the previous correction process is A2 or less, the current temperature change from the temperature at the previous correction process is B2 or less, and the previous color When the number of printed sheets from the end of the misregistration correction is C2 or less (step S705: No), since the color misregistration correction processing has already been executed once, the print processing is executed without performing further color misregistration correction processing ( Step S708).

  On the other hand, if the second condition is satisfied in step S705, that is, the elapsed time from the previous correction process is longer than A2, or the change in the current temperature from the temperature at the previous correction process is greater than B2. Alternatively, when the number of printed sheets from the end of the previous color misregistration correction is greater than C2 (step S705: Yes), the determination processing unit 31 has a skew correction amount as a result of the previous color misregistration correction processing (step S704). It is checked whether or not it is larger than the predetermined amount D (step S706).

  If the skew correction amount in the previous color misregistration correction process is equal to or less than the predetermined amount D (step S706: No), it is determined that the color misregistration correction is almost perfectly performed in the previous color misregistration correction process. Thus, the printing process is executed without further color misregistration correction (step S708).

  On the other hand, if the skew correction amount in the previous color misregistration correction process is larger than the predetermined amount D in step S706 (step S706: Yes), the determination processing unit 31 still has color misregistration due to the previous color misregistration correction process. It is determined that the correction is not complete, and it is determined that the color misregistration correction is to be performed once more, and the color misregistration correction processing is executed (step S708). Thereafter, a printing process is executed (step S708), and the number of printed sheets at this time is counted and stored in the memory 21 (step S709). As described above, the color misalignment correction process is performed once or twice according to the result of the previous first color misregistration correction process in addition to the operation condition and the environmental condition of the multifunction peripheral.

  Note that the specific processing of color misregistration correction in step S704 and step S707 is performed in the same manner as the color misregistration correction processing by the multifunction peripheral of the first embodiment described with reference to FIG.

  As described above, the MFP according to the second embodiment determines whether or not to perform further color misregistration correction processing based on the result of the first color misregistration correction processing, and performs further color misregistration correction processing only when necessary. Therefore, unnecessary color misregistration correction processing can be omitted, and color misregistration correction processing can be performed in a short time.

  Note that the color misregistration correction program executed by the MFPs of the first and second embodiments is provided by being incorporated in advance in a ROM or the like.

  The color misregistration correction program executed in the multifunction machine of the first and second embodiments is a file in an installable format or an executable format, and is a CD-ROM, flexible disk (FD), CD-R, DVD (Digital Versatile Disk). ) Or the like may be recorded and provided on a computer-readable recording medium.

  Further, the color misregistration correction program executed by the multifunction peripherals of the first and second embodiments may be provided by being stored on a computer connected to a network such as the Internet and downloaded via the network. good. In addition, the color misregistration correction program executed by the MFPs of the first and second embodiments may be provided or distributed via a network such as the Internet.

  The color misregistration correction program executed in the MFPs of the first and second embodiments includes the above-described correction amount calculation unit 20, determination processing unit 31, pattern detection unit 19, write control unit 22, and skew correction motor control unit 23. The module is configured, and as actual hardware, a CPU (processor) reads the color misregistration correction program from the ROM and executes it, whereby the above-described units are loaded onto the main storage device, and the correction amount calculation unit 20, determination A processing unit 31, a pattern detection unit 19, a writing control unit 22, and a skew correction motor control unit 23 are generated on the main storage device. Note that the correction amount calculation unit 20, the determination processing unit 31, the pattern detection unit 19, the write control unit 22, and the skew correction motor control unit 23 may be configured by hardware.

  It should be noted that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

FIG. 3 is a front view of an image forming unit, a writing unit, and a transfer belt for explaining an image forming principle of the color multifunction peripheral. 2 is a perspective view of the transfer belt 3 showing a state in which a correction pattern 14 is formed on the transfer belt 3. FIG. FIG. 2 is a block diagram illustrating a configuration of a mechanism that performs color misregistration correction of the multifunction peripheral according to the first embodiment. It is explanatory drawing which shows the relationship between the frequency | count of correction | amendment, and the precision of correction | amendment. 4 is a flowchart illustrating a procedure of overall processing for color misregistration correction by the multifunction peripheral according to the first embodiment; It is a flowchart which shows the procedure of the specific process of color misregistration correction. 6 is a flowchart illustrating a procedure of overall processing for color misregistration correction by the multifunction peripheral according to the second embodiment; It is a schematic diagram which shows the state in which skew deviation has arisen in the writing unit. It is a schematic diagram which shows the state of the correction pattern in case skew deviation has arisen.

Explanation of symbols

1Y, 1M, 1C, 1K Image forming unit 3 Transfer belt 4 Drive roller 7Y, 7M, 7C, 7K Photosensitive drum 8Y, 8M, 8C, 8K Charger 9 Writing unit 13 Fixing unit 14 Correction pattern 15, 16 Detection sensor 19 Pattern detection unit 20 Correction amount calculation unit 21 Memory 22 Write control unit 23 Skew correction motor control unit 24, 25, 26, 27 LD control unit 28, 29, 30 Skew correction motor 31 Judgment processing unit

Claims (10)

An image forming apparatus that includes an image forming unit that forms and superimposes images of a plurality of colors on an image carrier, and that performs image formation by transferring the image formed on the image carrier to a paper medium,
Pattern forming means for forming a correction pattern for correcting misregistration of each color on the image carrier;
Detecting means for detecting the correction pattern formed on the image carrier;
Based on the correction pattern detected by the detection means, a color misregistration amount due to a scanning line inclination of the image forming unit and a color misregistration amount other than the scanning line inclination are obtained, and correction for correcting each obtained color misregistration amount. Correction amount calculating means for calculating the amount;
Control means for controlling the image forming unit based on the correction amount calculated by the correction amount calculating means;
The pattern forming means, the detecting means, the correction amount calculating means, and the current time is after a predetermined first time has elapsed since the previous correction processing execution and before a second time longer than the first time. The number of color misregistration correction processes, which is a series of processes of the control means, is determined as one, and if the current time is after the second time has elapsed since the previous correction process execution, the number of times is determined as a plurality of times. And a determination processing unit that controls the pattern forming unit, the detection unit, the correction amount calculation unit, and the control unit so as to execute the color misregistration correction process a determined number of times.
An image forming apparatus comprising: The determination processing means further includes a case where the current temperature has changed more than a predetermined first temperature from a temperature at the time of the previous correction processing execution, and is not more than a second temperature higher than the first temperature. The number of times is determined as one time, and when the current temperature has changed more greatly than the second temperature from the temperature at the time of executing the correction process, the number of times is determined as a plurality of times. Item 2. The image forming apparatus according to Item 1. The determination processing unit further determines the number of times when the current image forming number is greater than a first predetermined amount and less than or equal to a second predetermined amount greater than the first predetermined amount from the end of the previous correction processing execution. It was determined once, when the current number of image formation and the second predetermined amount greater than the execution of the last correction process ends, according to claim 1 or 2, characterized in that to determine the number of a plurality of times The image forming apparatus described in 1.   The determination processing unit determines the number of times as a plurality of times when the image forming apparatus is turned on, and executes the color misregistration correction processing for the determined number of times. The image forming apparatus according to claim 1, wherein the correction amount calculating unit and the control unit are controlled. The determination processing unit determines the number of times as one during the image forming process after the first time has elapsed and before the second time has elapsed , and the color misregistration correction processing is performed by the determined number of times. the to run, the image forming apparatus according to claim 1, characterized in that for controlling said patterning means and the sensing means and the correction amount calculating means and the control means. The determination processing unit determines the number of times as one immediately before the image forming process after the first time has elapsed and before the second time has elapsed , and the color misregistration correction is performed by the determined number of times. such that the process, the image forming apparatus according to claim 1, characterized in that for controlling the said pattern forming means and said detection means and the correction amount calculating means and the control means.   The determination processing unit determines the number of times based on the result of the previous color misregistration correction processing, and executes the color misregistration correction processing for the determined number of times. 2. The image forming apparatus according to claim 1, wherein the correction amount calculating unit and the control unit are controlled. The determination processing unit increases the number of times by 1 when the scanning line inclination amount by the previous correction amount calculation unit is equal to or greater than a predetermined amount, and executes the color misregistration correction processing by the number of times. The image forming apparatus according to claim 7 , wherein the pattern forming unit, the detecting unit, the correction amount calculating unit, and the control unit are controlled. Color misregistration executed by an image forming apparatus that includes an image forming unit that forms an image of a plurality of colors on an image carrier, and transfers the image formed on the image carrier to a paper medium to form an image. A correction method,
Patterning means, the patterning step for forming a correction pattern for positional deviation correction for each color on the image bearing member,
Detection means comprises a detection step of detecting the correction pattern formed on the image bearing member,
Based on the correction pattern detected by the detection step , the correction amount calculation unit obtains the color misregistration amount due to the scanning line inclination of the image forming unit and the color misregistration amount other than the scanning line inclination, and obtains each color misregistration amount. A correction amount calculating step for calculating a correction amount for correcting
A control step for controlling the image forming unit based on the correction amount calculated by the correction amount calculating step;
The determination processing means is configured such that the pattern forming means, the detection means, and the current time are after a predetermined first time has elapsed since the previous correction processing execution and before a second time that is longer than the first time. The number of color misregistration correction processes, which is a series of processes of the correction amount calculation means and the control means, is determined as one, and when the current time is after the second time has elapsed since the previous correction processing execution, the number of times and a plurality of times and determining, determination processing step of controlling said patterning means as many times as determined to execute the color misalignment correction and the detection means and the correction amount calculating means and said control means,
A color misregistration correction method comprising: This is a program that includes an image forming unit that forms images of a plurality of colors on an image carrier, and that is executed by a computer that forms the image by transferring the image formed on the image carrier to a paper medium. And
A pattern forming step of forming a correction pattern for correcting misregistration of each color on the image carrier;
A detection step of detecting the correction pattern formed on the image carrier;
Based on the correction pattern detected by the detection step, a color misregistration amount due to the scanning line inclination of the image forming unit and a color misregistration amount other than the scanning line inclination are obtained, and correction for correcting each obtained color misregistration amount. A correction amount calculating step for calculating the amount;
A control step of controlling the image forming unit based on the correction amount calculated by the correction amount calculation step;
The current time is after the elapse of a predetermined first time since the previous correction processing execution and before the elapse of a second time longer than the first time, the pattern formation step, the detection step, the correction amount calculation step, The number of color misregistration correction processes, which is a series of processes in the control process, is determined as one, and when the current time is after the second time has elapsed since the previous correction process, the number of times is determined as a plurality of times. A determination processing step for controlling the pattern formation step, the detection step, the correction amount calculation step, and the control step so as to execute the color misregistration correction processing a determined number of times;
For causing the computer to execute.

Images