JP4708062B2 - Color image forming apparatus - Google Patents

Description

  The present invention provides a misregistration correction unit that outputs a toner pattern composed of a plurality of colors onto a transfer member, and performs color misregistration correction processing that corrects misregistration of each color based on information detected by the sensor. The present invention relates to a tandem type color image forming apparatus.

  2. Description of the Related Art Today, electrophotographic apparatuses are increasing in color output such as color copiers and color printers in response to market demands. In recent years, in particular, since monochrome speeds are desired for color output, a plurality of photoconductors and individual developing devices are provided, and single-color toner images are formed on the photoconductors. Tandem printers that transfer and record color images on paper have become mainstream.

  In the tandem printer, as shown in FIG. 15, the toner image formed by the developing unit (303K, 303M, 303C, 303Y) on each photoconductor (302K, 302M, 302C, 302Y) is transferred to the transfer device (304K). , 304M, 304C, 304Y) and a direct transfer system that sequentially transfers onto a sheet (not shown) conveyed by the transfer belt 310, and as shown in FIG. 16, each photoconductor (302K, 302M, 302C, 302Y), the toner images formed by the developing units (303K, 303M, 303C, 303Y) are temporarily transferred onto the transfer belt 310 once by the transfer device (304K, 304M, 304C, 304Y). Indirect transfer system that batch transfers images onto paper by secondary transfer device 320 There are, in the secondary transfer device 320 is often to adopt a configuration using a belt.

  By the way, in both of the direct transfer method and the indirect transfer method, the image on the photosensitive member of each color is transferred onto the paper or the belt at different positions on the transfer belt 310, so that the moving speed of the transfer belt 310 is very small. If there is a significant change, the arrival time to the next color transfer position will fluctuate, causing a shift in the transfer position of each color, resulting in a color shift in the sub-scanning direction in the output image. It will be.

  Also, since the writing units (301K, 301M, 301C, 301Y) are independent for each color, the magnification in the main scanning direction and the writing position change due to the displacement of the components due to environmental changes such as temperature. As a result, a color shift in the main scanning direction occurs in the output image.

  Therefore, the color image forming apparatus disclosed in Patent Document 1 outputs a toner pattern tp for detecting misregistration as shown in FIG. 17 on the transfer belt 310 before forming an actual color image. The pattern tp is detected by the toner mark sensor 315, the amount of deviation from the normal position of each color and the amount of correction are calculated from the detection result, and the image writing timing and magnification are corrected based on the amount of correction. Deviation correction is performed. When the actual color misregistration amount is detected, the toner mark sensor 315 detects and outputs a toner pattern tp for detecting misregistration as shown in FIG. 17 a plurality of times along the belt moving direction. By averaging the detected values, processing for reducing the influence of fluctuations due to noise and mechanical variations and improving the accuracy of the detected values is performed.

JP 2002-244387 A

  Incidentally, in order to improve the detection accuracy in the color image forming apparatus disclosed in Patent Document 1, it is effective to increase the number of repetitions of the pattern tp. In this case, however, one color is proportional to the number of repetitions. Since the time required for correcting the deviation becomes long, there is a problem that the throughput is deteriorated and the usability of the user is deteriorated.

  Also, even if the number of repetitions is increased, the detection accuracy is hardly improved from a certain number of times, and the influence of environmental fluctuations is affected when the machine installation environment or consumable parts such as the photoconductor and transfer belt are replaced. In addition, since the variation condition of the color shift changes due to variations in the accuracy of parts, there is a problem that it is difficult to set the optimum condition.

  Although it is possible for the user to set the correction of the number of repetitions according to the color misregistration state, there is a problem that it is difficult and troublesome to set the optimum number of times.

  The present invention has been made in view of the above, and it is possible to optimize the execution time required for the color misregistration correction process, improve the total throughput, and improve the usability of the user. An object is to provide a color image forming apparatus.

In order to solve the above-described problems and achieve the object, the invention according to claim 1 generates a toner pattern composed of a plurality of colors at a transfer portion and outputs the toner pattern onto a transfer body. In a tandem type color image forming apparatus having color misregistration correction means for performing color misregistration correction processing for correcting color misregistration of each color based on the detected information, it is detected during the color misregistration correction processing by the color misregistration correction means. The next color misregistration correction processing by the color misregistration correction means according to the maximum difference value that is the maximum between the respective colors among the difference values of the color misregistration amounts obtained for each repetition number of the toner pattern of each color other than the reference color. the number of output times of the toner pattern during said maximum if the difference value is larger than the predetermined color shift correction tolerance increases the number of repetitions of the toner pattern, the maximum difference value If less than the color shift correction tolerance, comprises a first output count changing means for changing the number of repetitions of the toner pattern to the smallest number of repetitions that the maximum difference value is less than the color shift correction tolerance.

The invention according to claim 2, in the color image forming apparatus according to claim 1, wherein, when the color misregistration correction processing by the color shift correcting means, temperature detecting means for detecting a device internal temperature or device ambient temperature, and temperature change detection means for detecting a temperature change of the temperature at which the temperature and the previous color shift correction process detected by the temperature detecting means, in accordance with the temperature variation detected by the temperature change detection means, wherein the color shift correction Second output number changing means for changing the number of times of output of the toner pattern at the time of color misregistration correction processing by the means.

The invention according to claim 3, in the color image forming apparatus according to claim 1, the elapsed time counting means for counting the elapsed time from the color misregistration correction processing by the previous said color shift correction unit, wherein the color shift correction depending on the time elapsed from the color misregistration correction processing by the previous said color shift correction means clocked by said elapsed time counting means during the color misregistration correction processing by means of the time of color misregistration correction processing by the color misregistration correction means Second output number changing means for changing the number of output times of the toner pattern.

The invention according to claim 4, in the color image forming apparatus according to claim 1, wherein, when the color misregistration correction processing by the color shift correcting means, that freely exchange unit detachable to the apparatus has been replaced a unit replacement detecting means for detecting, when the replacement unit has detected that it has been replaced by the unit replacement detecting means, the maximum value of output times of the toner pattern when the color misregistration correction processing by the color misregistration correction means or current Second output number changing means for changing to a value obtained by adding a certain number of times to the set value .

  According to a fifth aspect of the present invention, in the color image forming apparatus according to any one of the first to fourth aspects, the structure of the transfer unit is a direct transfer system.

  According to a sixth aspect of the present invention, in the color image forming apparatus according to any one of the first to fourth aspects, the configuration of the transfer unit is an indirect transfer system.

According to the first aspect of the present invention, among the difference values of the color misregistration amounts obtained for each number of repetitions of the toner pattern for each color other than the reference color detected during the color misregistration correction processing by the color misregistration correction means , between each color. in accordance with the maximum difference value becomes the maximum, in the case greater than the next color shift of output times of the toner pattern when the color misregistration correction processing by the correction means, color maximum difference value is a predetermined deviation correction tolerance toner increase the number of repetitions of the pattern, if the maximum difference value is less than the color shift correction tolerance, between Turkey be changed to minimize the number of repetitions of the number of repetitions of the toner pattern is the maximum differential value falls below the color shift correction tolerance The execution time required for the color misregistration correction process can be optimized, the total throughput can be improved, and the user convenience can be improved.

According to the second aspect of the present invention, by changing the number of times the toner pattern is output during the color misregistration correction process by the color misregistration correction unit in accordance with the temperature change amount detected by the temperature change detection unit, the apparatus Even when the environmental condition in which the toner is installed changes, it is possible to maintain the detection accuracy corresponding to the change in the amount of color misregistration in the number of patterns used for each color toner pattern .

Further, according to the invention according to claim 3, according to the elapsed time from the color misregistration correction processing by the previous color misregistration correction means clocked by the elapsed time counting means during the color misregistration correction processing by color shift correction means, by changing the output frequency of the toner pattern when the color misregistration correction processing by the color shift correcting unit, when installed environment state of the device has changed also, the color shift in the number of patterns used for each color toner pattern The detection accuracy for the amount of change can be maintained.

Further, according to the invention according to claim 4, when detecting that the replaceable unit has been replaced by a unit replacement detecting means, changing the number of output times of the toner pattern when the color misregistration correction processing by color shift correction means Accordingly, when the state of the device has changed it may also be maintained the detection accuracy of the change in the amount of color shift in the number of patterns used for each color toner pattern.

  According to the fifth aspect of the present invention, in the color image forming apparatus in which the structure of the transfer portion is the direct transfer method, the same effect as that of the first aspect of the present invention can be obtained. .

  According to the invention of claim 6, in the color image forming apparatus in which the configuration of the transfer portion is an indirect transfer system, the same function and effect as in the invention of any one of claims 1 to 4 can be obtained. .

  Exemplary embodiments of a color image forming apparatus according to the present invention will be explained below in detail with reference to the accompanying drawings. The color image forming apparatus according to the present invention performs a color misregistration correction process for outputting a toner pattern composed of a plurality of colors on a transfer body and correcting the misregistration of each color based on information detected by the sensor. This is a tandem type color image forming apparatus having a misregistration correction unit to be performed.

[First Embodiment]
A first embodiment of the present invention will be described with reference to FIGS. In this embodiment, a color laser printer is applied as a color image forming apparatus.

  FIG. 1 is a block diagram showing the configuration of the color laser printer according to the first embodiment of the present invention.

  A CPU (Central Processing Unit) 100 executes a program written in a ROM (Read Only Memory) 101 to control each part of the apparatus.

  The ROM 101 stores a program for the CPU 100 to control each part of the apparatus and fixed data used for control.

  A RAM (Random Access Memory) 102 is used to develop a work area during execution of a program for controlling each part of the apparatus and an image to be printed.

  The parameter memory 103 is a non-volatile memory for storing data related to the operation of the apparatus even when the power is shut off and storing data that is referred to during the next operation. It is composed of an EEPROM. Parameters that are described later, such as the color misregistration correction execution interval and the number of repetitions of the color misregistration correction toner pattern, and data that is updated during the color misregistration correction, such as the color misregistration correction amount, are stored in this memory. Shall.

  The time measuring unit 104 uses a clock inside the system and counts the clock to measure the elapsed time from the previous execution of the color misregistration correction process. The time measuring unit 104 has a clock function for measuring the time, and is configured to measure the time when the color misregistration correction processing is performed, and the elapsed time from the time when the color misregistration correction processing is performed based on the difference from the current time. It is good also as a structure which calculates.

  The operation display unit 105 includes operation keys for the user to set the device and the like, and a display unit such as a liquid crystal display for displaying the operation state and message of the device to the user.

  The plotter 106 is an apparatus that forms and outputs an image on a recording sheet.

  The I / O unit 107 includes an input / output port, and performs input and various control outputs of the toner mark sensor 108 and other sensors.

  The toner mark sensor 108 is a sensor that detects a toner pattern generated on the transfer belt 51 (see FIG. 2) that is a transfer body. When an optical sensor is used, the color shift amount is measured by irradiating the transfer belt 51 with light and detecting reflected light from the toner pattern for measuring the color shift amount generated on the transfer belt 51. To get information to do.

  The temperature detection sensor 109 is a sensor for detecting the environmental temperature, and functions as temperature detection means for detecting the internal temperature or the ambient temperature of the image forming apparatus using a temperature sensor such as a thermistor.

  The motor 112 is a motor that drives each unit, and is controlled by a drive signal supplied from the motor control circuit 110 via the motor drive circuit 111.

  The system bus 113 is a signal line for the above-described units to exchange data. Specifically, the system bus 113 is configured as a set of a data bus, an address bus, a control bus, and an I / O bus.

  Next, the plotter 106 will be described in detail. Here, FIG. 2 is a configuration diagram schematically showing the configuration of the plotter 106. As shown in FIG. 2, the plotter 106 is of a tandem type by electrophotography, and has four drum-shaped photosensitive drums (2K, 2M, 2C, 2Y) and the photosensitive drums (2K, 2M, 2C, 2Y) A belt-like conveying device (carrying a sheet so that an image formed on the sheet is sequentially transferred onto a sheet (not shown) at a transfer position of each transfer device (4K, 4M, 4C, 4Y)). Hereinafter, the structure of the direct transfer system including the transfer belt 51) is employed.

  First, the image data is decomposed into image data of each color of cyan (C), magenta (M), yellow (Y), and black (K) by the plotter control unit 7 and converted into data of each color for writing. The photosensitive drums (2K, 2M, 2C, 2Y) are exposed to light such as a laser output from the writing unit (1K, 1M, 1C, 1Y), and are exposed on the photosensitive drums (2K, 2M, 2C, 2Y). An electrostatic latent image corresponding to the image data is formed.

  The electrostatic latent images formed on the photosensitive drums (2K, 2M, 2C, 2Y) are developed by the developing devices (3K, 3M, 3C, 3Y) corresponding to the respective colors to become toner images of the respective colors.

  The toner images of the respective colors developed in this way are transferred onto the paper by the transfer unit 4, and a color image is formed on the paper.

  The transfer unit 4 includes a transfer belt 51 that contacts the photosensitive drums (2K, 2M, 2C, and 2Y) of each color and a transfer roller (4K, 4M, 4C, and 4Y) that faces the photosensitive drums (2K, 2M, 2C, and 2Y). ). The sheet is transported on the transfer belt 51, and the toner image is transferred to the sheet when it comes into contact with each photosensitive drum (2K, 2M, 2C, 2Y).

  The transfer belt 51 is an endless belt that is stretched between the driving roller 52 and the driven roller 53, and is operated at a constant speed by a motor 112 (see FIG. 1) connected to the shaft of the driving roller 52. Driven. A cleaning device 54 is installed downstream of the driving roller 52 to clean an unnecessary toner image on the surface of the transfer belt 51. As the transfer belt 51, for example, a belt in which the entire belt layer is formed of fluorine resin, polycarbonate resin, polyimide resin or the like, or an elastic belt in which a part of the belt is formed is used.

  A fixing unit 6 is provided on the downstream side of the transfer belt 51 in the conveyance direction. In the fixing unit 6, the sheet on which the toner image of each color is transferred is fixed on the sheet by heating and pressurizing and output.

  Next, color misregistration correction processing of this color laser printer will be described.

  In general, the color misregistration correction processing is performed by detecting a color misregistration correction pattern composed of four different strip-shaped toner patterns formed on the transfer belt 51 by the toner mark sensor 108, and the pattern of each color. The amount of color misregistration is detected in the meantime, and the writing timing or the like is corrected so that the amount of color misregistration becomes a predetermined value or less.

  An example of the toner pattern TP used for the color misregistration correction process is shown in FIG. As shown in FIG. 3, the toner pattern TP outputs a series of strip-shaped toner patterns TP to a plurality of locations in the main scanning direction in accordance with the arrangement of the toner mark sensors 108. Note that the number of repetitions of the toner pattern TP is stored in the parameter memory 103.

  Each toner pattern TP has four parallel patterns and four diagonal lines arranged at regular intervals in the sub-scanning direction, and a plurality of sets of them are repeatedly formed along the moving direction of the transfer belt 51. Is. Here, the four patterns forming the toner pattern TP are formed with four colors of cyan (C), magenta (M), yellow (Y), and black (K).

  Color misregistration correction processing using this toner pattern TP will be described with reference to the flowchart shown in FIG.

  First, prior to normal image output, a toner pattern TP for detecting a color misregistration amount between colors is output (step S1). The toner pattern TP is formed on the transfer belt 51 through the photosensitive drums (2K, 2M, 2C, 2Y).

  Next, the toner pattern TP for detecting color misregistration formed on the transfer belt 51 is detected by the toner mark sensor 108, and the position information of each line pattern is detected (step S2).

  In the subsequent step S3, the skew, the amount of deviation in the main scanning direction, and the amount of deviation in the sub-scanning direction are calculated from the edge information of each line pattern detected in step S2, and the correction amount that minimizes the deviation between these colors is calculated. To do. The calculated shift amount and correction amount are stored in the parameter memory 103 and used as correction values until the next color shift correction process.

  Then, using the correction amount calculated in step S3, the main-scanning and sub-scanning resists are corrected. Also, the magnification and the magnification error deviation are corrected (step S4).

  Next, in a state where the correction result of the color misregistration correction process in step S4 is reflected, the toner pattern TP for color misregistration detection is output again, and the toner pattern TP after the color misregistration correction is formed on the transfer belt 51 ( Step S5). The uncorrected toner pattern TP first formed on the transfer belt 51 is removed by the cleaning device 54 after detection by the toner mark sensor 108.

  In the subsequent step S6, the color misregistration detection toner pattern TP on the transfer belt 51 after the color misregistration correction is detected again by the toner mark sensor 108, and each position information of the line pattern is detected.

  Next, from the detected edge information of each line pattern, the skew, the amount of deviation in the main scanning direction, and the amount of deviation in the sub-scanning direction are calculated as before, and the correction amount that minimizes the deviation between these colors is calculated. (Step S7).

  Finally, it is determined whether or not the amount of color misregistration between the patterns after the color misregistration correction is smaller than a predetermined value (Δd) (step S8). If it is larger than Δd (N in step S8), the processes in and after step S4 are repeated based on the correction amount calculated in step S7. On the other hand, if it is smaller than Δd (Y in step S8), it is determined that the correction has been completed, and the process ends.

  By performing a series of processes as described above, it is possible to correct the color misregistration amount between the colors to a value smaller than a predetermined value (Δd).

  In this example, the color misregistration correction process is performed once, and the color misregistration detection pattern is output again with the correction result reflected to reduce the misregistration amount to a predetermined value or less. When giving priority, it is good also as operation | movement complete | finished by the process to step S3.

  Here, a toner pattern TP composed of a plurality of colors is generated by the transfer unit 4 and output onto a transfer belt 51 as a transfer body, and the toner pattern TP of each color is determined based on information detected by the toner mark sensor 108. A misregistration correction unit that performs color misregistration correction processing for correcting misregistration is realized.

  Next, characteristic functions that are exhibited when the CPU 100 of the color laser printer according to the present embodiment operates in accordance with a program written in the ROM 101 will be described. A characteristic function of the color laser printer of this embodiment is that when a preset number of pages are output during continuous printing, printing is interrupted once and the above-described color misregistration correction processing is performed, so that an output image is always output. The amount of color misregistration is kept within a certain range.

  FIG. 5 is a flowchart showing the flow of a printing process including a process for changing the number of repetitions of the toner pattern TP, which is a characteristic process in the color laser printer of this embodiment. As shown in FIG. 5, when the power is turned on (step S11), first, an initialization operation for printing preparation is performed (step S12).

  When the initialization operation is completed, if a print request is not issued, the process waits as it is (step S13). When a print request is issued (Y in step S13), the process proceeds to image output processing.

  In the image output process, first, the aforementioned color misregistration correction process is executed (step S14). In the color misregistration correction process (step S14), as described above, the toner pattern TP for color misregistration detection is formed on the transfer belt 51, the toner pattern TP is detected by the toner mark sensor 108, and the color misregistration is detected from the detected value. This is a process for obtaining the amount and correcting the resist and magnification in the main scanning direction and the sub-scanning direction to minimize the color misregistration of the four colors. Since the calculated shift amount and correction amount are used as correction values until the next color shift correction process, they are stored in the parameter memory 103.

  When the color misregistration correction process (step S14) is completed, the printing process is executed in a state where the correction amount stored in the parameter memory is reflected, and one page of image is output (step S15). Each time one page is output, it is determined whether or not the preset number of pages (n pages) has been reached (step S16), and the set number of pages (n pages) has been reached. If not (N in Step S16), it is determined whether or not it is the last page (Step S17). If it is not the last page (N in Step S17), the process returns to Step S15 to output the next page. If it is the last page (Y in step S17), the output process is terminated, the process returns to step S13, and a transition is made to a standby state for the next print request.

  On the other hand, when the preset number of pages (n pages) has been reached (Y in step S16), it is determined that the color misregistration amount may be larger than the allowable range, and the color misregistration correction process is performed again. Is executed (step S18). In this color misregistration correction process, the toner pattern TP is output using the number of repetitions currently stored in the parameter memory 103, and the correction process is performed by detecting the color misregistration amount. Since the calculated shift amount and correction amount are used as correction values until the next color shift correction process, the contents of the parameter memory 103 are updated and stored.

  Next, a process of changing the number of repetitions of the toner pattern TP during the color misregistration correction process is performed according to the color misregistration amount detected in the color misregistration correction process (step S18).

Here, the amount of color misregistration detected in the color misregistration correction process (step S18) will be described. For the detection of the color misregistration amount, a set of toner patterns TP surrounded by thin lines in FIG. The amount of color misregistration is possible with this one set of toner pattern TP. As shown in FIG. 6, the color misregistration amount ΔM in the sub-scanning direction of magenta (M) when black (K) is the reference color is the distance between black (K) and magenta (M) detected in FIG. A value obtained by subtracting a normal value Δ (M ₀ −K ₀ ) from Δ (M−K). Assuming that a maximum of 20 sets of toner patterns TP are repeatedly output, the color misregistration amount of magenta (M) is obtained for each set, and the obtained color misregistration amounts are Δm ₁ , Δm ₂ , Δm ₃ , Δm _{4, respectively.} ···· Δm ₂₀

For the color misregistration amount thus obtained, in the color misregistration correction processing, in order to improve the detection accuracy, as shown in FIG. 3, a plurality of toner patterns TP are repeatedly output, and each toner pattern is output. A color misregistration amount is calculated for each set of TPs, and a value obtained by averaging the color misregistration amounts obtained for each set is set as a final color misregistration amount. The color misregistration amount is obtained by performing an averaging process. At this time, the color misregistration amount when the number of averaging processes is changed is defined and calculated as follows.
Color shift obtained in only one set amount ΔM ₁ ΔM ₁ = Δm ₁
Color misregistration amount obtained in one or two sets ΔM ₂ ΔM ₂ = (Δm ₁ + Δm ₂ ) / 2
Color misregistration amount ΔM ₃ ΔM ₃ = (Δm ₁ + Δm ₂ + Δm ₃ ) / 3 obtained from 1 to 3 sets
...
Color misregistration amount ΔM ₂₀ ΔM ₂₀ obtained from 1 to 20 sets = (Δm ₁ + Δm ₂ ... + Δm ₂₀ ) / 20

  Here, FIG. 7 is a graph showing the amount of color misregistration when the number of times of averaging is changed. As can be seen from FIG. 7, generally, when the number of times of averaging is increased, the detected color misregistration amount converges to a constant value.

Next, the color shift amount ΔM ₁ ~ΔM ₂₀ determined to calculate the variation due to the increase in number of repetitions. A difference value ΔM ₁ −ΔM ₂ between the color misregistration amount ΔM ₁ obtained by only one set and the color misregistration amount ΔM ₂ obtained by one or two sets is represented by δM _1, and changes in δM _{1 to} δM ₁₉ are graphed. As shown in FIG.

Here has been described the magenta (M), the same applies to the two colors other than the other of the reference color black (K) [delta] Y, seeking .delta.C, was determined for each number of repetitions, .DELTA.M _n, [delta] Y _{n, Let} the maximum value of δC _{n be} δD _n . A graph of δD _n is as shown in FIG.

Next, the calculated δD _n is compared with a predetermined color misregistration correction allowable value Δd, and processing for changing the number of repetitions of the toner pattern TP to an optimum value is performed. Δd used here
Is the color misregistration correction allowable value and is the minimum value of the correction resolution of color misregistration correction control.

That is, the variation δDp of the color misregistration amount at the number of patterns p used this time and the color misregistration correction allowable value Δd are compared (step S19), and the variation δ of the color misregistration amount at the number of patterns p used this time is compared.
If Dp is larger than the color misregistration correction allowable value Δd (Y in step S19), the color misregistration correction accuracy is improved by increasing the number of repetitions of the toner pattern TP (step S20). More specifically, the number of repetitions p of the color misregistration correction pattern is changed to the minimum number of repetitions p ′ where the color misregistration amount is less than Δd, and the time required for color misregistration correction becomes longer, but is repeated in the direction in which the correction accuracy is improved. Change the number of times setting.

On the other hand, the variation δDp of the color misregistration amount at the number of patterns p used this time is the color misregistration correction allowable value Δd.
If it is smaller (N in step S19, Y in step S21), the accuracy will not be improved even if the number of repetitions of the toner pattern TP is increased. The number of repetitions is changed to p ″, and the setting value of the number of repetitions is changed in a direction to shorten the time required for color misregistration correction (step S22).

  If the result of execution with 13 iterations is as shown in FIG. 9, the color misregistration correction accuracy is not improved when the iteration number is 7 or more, so the iteration number is set to 7. .

  Through the series of processes described above, it is possible to optimize detection accuracy and execution time by updating the number of repetitions of the toner pattern TP in accordance with the color misregistration amount at the time of color misregistration correction. Here, the function of the first output number changing means is executed.

  As described above, according to the present embodiment, the toner pattern at the time of the color misregistration correction process performed by the next misregistration correction unit according to the variation amount of the misregistration of each color detected during the color misregistration correction process by the misregistration correction unit. Change the output count of. For example, if the amount of change in color misregistration detected during color misregistration correction processing is smaller than a predetermined value, the number of times the toner pattern is output during the next color misregistration correction processing is set to a value smaller than the current set value, If the amount is larger than the predetermined value, the execution time required for the color misregistration correction process can be optimized by increasing the number of times the toner pattern is output during the next color misregistration correction process from the current set value. As a result, the total throughput can be improved and user convenience can be improved.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is also omitted.

  In the present embodiment, a temperature change is detected during the color misregistration correction process in the printing process including the toner pattern TP repetition count changing process described in the first embodiment, and the detected temperature change amount is a preset value. If larger, the color misregistration correction is executed by changing the number of repetitions of the toner pattern TP during the color misregistration correction process.

  The reason why the number of repetitions of the toner pattern TP is changed in accordance with the temperature change amount in this way is as follows. Since the environment in which the color laser printer is installed is not constant, the number of pattern outputs determined during the previous color misregistration correction process is not necessarily the optimum number of times during the next color misregistration correction process. In particular, when there is a large environmental change such as temperature since the previous color misregistration correction process, there is a high possibility that the components of the color laser printer will be displaced, so the number of times of output of the toner pattern TP for color misregistration correction determined last time is high. This is because when the color misregistration correction process is performed, the time required for the color misregistration correction process can be shortened, but the accuracy of the color misregistration correction may be reduced.

  FIG. 10 is a flowchart showing the flow of the printing process including the process of changing the number of repetitions of the toner pattern TP, which is a characteristic process in the color laser printer of this embodiment. As shown in FIG. 10, in the present embodiment, in the image output process after the print request (Y in step S13), first, temperature measurement is performed (step S31), and the previous color misregistration correction process is performed. Comparison with temperature is performed (step S32: temperature change detection means). The temperature is measured using a temperature detection sensor 109 such as a thermistor. The output signal of the temperature detection sensor 109 is A / D converted by the I / O unit 107 and converted into a temperature for use. The detected temperature is the temperature at the current color misregistration correction process, and is stored in the parameter memory 103 because it is used at the next color misregistration correction process.

If the temperature measured this time is larger than a preset value ΔT (Y in step S32) compared to the temperature at the previous color misregistration correction process, it is determined that the influence of the temperature change is large, and the toner pattern The number of repetitions of TP is changed to the maximum value (step S33: second output number changing means), and color misregistration correction processing is executed (step S14). Although the number of repetitions of the toner pattern TP is changed to the maximum value here, it may be changed to a value obtained by adding a certain number of times to the current set value.

On the other hand, when the temperature measured this time is smaller than the preset value ΔT compared to the temperature at the time of the previous color misregistration correction process (N in step S32), it is determined that the influence of the temperature change is small. The color misregistration correction process is executed while maintaining the number of repetitions of the toner pattern TP determined during the previous color misregistration correction process (step S14).

  Further, in the present embodiment, as shown in FIG. 10, after the color misregistration correction process is performed again (step S18), the temperature is measured (step S34). The detected temperature is the temperature at the current color misregistration correction process, and is stored in the parameter memory 103 because it is used at the next color misregistration correction process.

  Next, a process of changing the number of repetitions of the toner pattern TP during the color misregistration correction process is performed according to the color misregistration amount detected in the color misregistration correction process (step S18). Since the process for changing the number of repetitions of the toner pattern TP during the color misregistration correction process is not different from that described in the first embodiment, the description thereof is omitted.

  Through the series of processes described above, it is possible to optimize detection accuracy and execution time by updating the number of repetitions of the toner pattern TP in accordance with the color misregistration amount at the time of color misregistration correction.

  As described above, according to the present embodiment, the number of times of output of the toner pattern during the color misregistration correction processing by the misregistration correction unit is changed according to the temperature change amount detected by the temperature change detection unit. Even when the installed environmental state changes, it is possible to maintain the detection accuracy of the variation amount of the positional deviation of each color.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is also omitted.

  In this embodiment, in the printing process including the process for changing the number of repetitions of the toner pattern TP described in the first embodiment, the elapsed time from the previous color misregistration correction process is detected during the color misregistration correction process, and the detection is performed. If the elapsed time is greater than a preset value, the color misregistration correction is executed by changing the number of times the toner pattern is repeated during the color misregistration correction process.

  The reason why the number of repetitions of the toner pattern TP is changed according to the elapsed time from the previous color misregistration correction process is as follows. Since the environment in which the color laser printer is installed is not constant, the number of output times of the toner pattern TP determined at the previous color misregistration correction process is not always the optimum number of output times at the next color misregistration correction process. In particular, if the elapsed time from the previous color misregistration correction process is large, there is a high possibility that the components of the color laser printer will be displaced. Therefore, the color misregistration correction is performed based on the number of times the toner pattern TP for color misregistration correction determined previously is output. This is because when processing is performed, the time required for color misregistration correction processing can be shortened, but the accuracy of correction may be reduced.

  FIG. 11 is a flowchart showing the flow of a printing process including a process for changing the number of repetitions of the toner pattern TP, which is a characteristic process in the color laser printer of this embodiment. As shown in FIG. 11, in the present embodiment, in the image output process after a print request (Y in step S13), first, time measurement is performed (step S41), and from the previous color misregistration correction process. Is measured (step S42: elapsed time measuring means). The time is measured using the time measuring unit 104. The time measuring unit 104 measures an elapsed time from the previous execution of the color misregistration correction process by counting the clocks in the system. In addition, it is good also as a structure which has the clock function for measuring time, measures the time which performed color misregistration correction processing, and calculates the elapsed time from the time of color misregistration correction execution from the difference with the present time. . When the time measurement is completed, the counter inside the time measurement unit 104 is reset, and the measurement of the time until the next color misregistration correction process is started.

If the elapsed time from the previous color misregistration correction process measured this time is larger than a preset value Δt (Y in step S42), it is determined that the influence of the environmental change is large, and the toner pattern TP The number of repetitions is changed to the maximum value (step S43: second output number changing means), and color misregistration correction processing is executed (step S14). Although the number of repetitions of the toner pattern TP is changed to the maximum value here, it may be changed to a value obtained by adding a certain number of times to the current set value.

On the other hand, if the elapsed time from the previous color misregistration correction process measured this time is smaller than the preset value Δt (N in step S42), it is determined that the influence of the environmental change is small, and the previous time. The color misregistration correction process is executed while maintaining the number of repetitions of the toner pattern TP determined during the color misregistration correction process (step S14).

  Furthermore, in the present embodiment, as shown in FIG. 11, after executing the color misregistration correction process again (step S18), the counter inside the time measuring unit 104 is reset and until the next color misregistration correction process. Measurement of the time is started (step S44).

  Next, a process of changing the number of repetitions of the toner pattern TP during the color misregistration correction process is performed according to the color misregistration amount detected in the color misregistration correction process (step S18). Since the process for changing the number of repetitions of the toner pattern TP during the color misregistration correction process is not different from that described in the first embodiment, the description thereof is omitted.

  Through the series of processes described above, it is possible to optimize detection accuracy and execution time by updating the number of repetitions of the toner pattern TP in accordance with the color misregistration amount at the time of color misregistration correction.

  As described above, according to the present embodiment, in accordance with the elapsed time from the previous color misregistration correction process by the misregistration correction means measured by the elapsed time timing means during the color misregistration correction process by the misregistration correction means, the position By changing the number of times the toner pattern is output during the color misregistration correction process by the misregistration correction means, the detection accuracy of the amount of variation in the misregistration of each color can be maintained even when the environmental state in which the apparatus is installed changes. Can do.

  The time measuring unit 104 may be configured to use a battery-backed real time clock. The real-time clock is an IC dedicated to timekeeping and operates with very low power consumption. Therefore, the real-time clock can be operated while the system is turned off by backing up with a battery. Therefore, even if the device is turned off, it is possible to measure the elapsed time since the previous color misregistration correction process. The same effect can be obtained when the power is turned on.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIGS. The same parts as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is also omitted.

  In the present embodiment, in the printing process including the process for changing the number of repetitions of the toner pattern TP described in the first embodiment, the intermediate transfer unit and the photosensitive unit are not used during the color misregistration correction process since the previous color misregistration correction process. When it is detected that a replacement unit such as a body unit has been replaced, color misregistration correction is executed by changing the number of repetitions of the toner pattern during the color misregistration correction processing.

  When it is detected that the replacement unit has been replaced as described above, the number of repetitions of the toner pattern TP during the color misregistration correction process is changed for the following reason. Since the environment in which the color laser printer is installed is not constant, the number of output times of the toner pattern TP determined at the previous color misregistration correction process is not always the optimum number of output times at the next color misregistration correction process. In particular, if a replacement unit such as an intermediate transfer unit or photoconductor unit has been replaced by the user during the previous color misregistration correction process, the component parts of the device are likely to be displaced. This is because the determined number of output times of the toner pattern TP for correcting color misregistration is not optimal and may reduce the accuracy of correction.

  FIG. 12 is a flowchart showing the flow of a printing process including a process for changing the number of repetitions of the toner pattern TP, which is a characteristic process in the color laser printer of this embodiment. As shown in FIG. 12, in this embodiment, in the image output process after the print request (Y in step S13), first, a new article detection process is executed (step S51: unit replacement detection means), Between the time of color misregistration correction processing, processing for confirming whether the replacement unit of the photoconductor unit or the intermediate transfer unit has been performed is performed.

  Here, it is assumed that a replacement unit such as a photoconductor unit or an intermediate transfer unit is provided with a new article detection mechanism that can detect the replacement. As a new article detection mechanism, as shown in FIG. 13, in the replacement unit 200 such as a photosensitive unit or an intermediate transfer unit, when the rotating member in the replacement unit 200 is rotated more than a predetermined rotation, the shape of the convex portion becomes flat. A detection member 202 is provided. On the other hand, a new article detection switch 203 which is a push switch is provided at a position facing the detection member 202 on the apparatus main body 201 side. Then, the detection member 202 of the replacement unit 200 is installed in the apparatus main body 201, and the apparatus main body 201 side electrically detects whether the new article detection switch 203 is open or closed by the action of the detection member 202, It is good also as a structure which judges a closed time as a new unit.

  Further, as shown in FIG. 14, a detection member 204 that mechanically disconnects when the rotation member in the replacement unit 200 is rotated more than a predetermined rotation is provided inside the replacement unit 200 such as the photosensitive unit or the intermediate transfer unit. Then, the replacement unit 200 is installed at an opposite location on the apparatus main body 201 side, and the apparatus main body 201 side electrically detects whether the detection member 204 is open or closed. Also good.

  If it is detected that the replacement unit has been replaced (Y in step S51), the number of repetitions of the toner pattern TP is changed to the maximum value (step S52: second output number changing means), and the color misregistration correction process is performed. Execute (Step S14). Although the number of repetitions of the toner pattern TP is changed to the maximum value here, it may be changed to a value obtained by adding a certain number of times to the current set value.

  On the other hand, when it is not detected that the replacement unit has been replaced (N in step S51), the color misregistration correction process is executed with the number of repetitions of the toner pattern TP determined in the previous color misregistration correction process. (Step S14).

  Since the following processing is not different from that described in the first embodiment, description thereof is omitted.

  Through the series of processes described above, it is possible to optimize detection accuracy and execution time by updating the number of repetitions of the toner pattern TP in accordance with the color misregistration amount at the time of color misregistration correction.

  As described above, according to the present embodiment, when the replacement unit is detected by the unit replacement detection unit, the number of times the toner pattern is output during the color misregistration correction process by the misregistration correction unit is changed. Even when the state of the apparatus changes, it is possible to maintain the detection accuracy of the variation amount of the positional deviation of each color.

  In each of the embodiments, an example of application to a direct transfer type color laser printer has been described. This can also be applied to the color laser printer (see FIG. 16).

1 is a block diagram showing a configuration of a color laser printer according to a first embodiment of the present invention. It is a block diagram which shows the structure of a plotter schematically. 3 is a plan view illustrating an example of a toner pattern used for color misregistration correction processing. FIG. It is a flowchart which shows the flow of a color shift correction process. 6 is a flowchart illustrating a flow of a printing process including a toner pattern repetition count changing process. It is explanatory drawing which shows the example of a color shift detection. It is a graph which shows the amount of color shift when changing the frequency | count of averaging. It is a graph which shows the amount of color shift when changing the frequency | count of averaging. It is a graph which shows the amount of color shift when changing the frequency | count of averaging. 10 is a flowchart illustrating a flow of a printing process including a toner pattern repetition count changing process according to a second embodiment of the present invention. 10 is a flowchart illustrating a flow of a printing process including a toner pattern repetition count changing process according to a third embodiment of the present invention. 10 is a flowchart illustrating a flow of a printing process including a toner pattern repetition count changing process according to a fourth embodiment of the present invention. It is a block diagram which shows an example of a new article detection mechanism. It is a block diagram which shows an example of a new article detection mechanism. 1 is a block diagram illustrating a configuration of a direct transfer tandem laser printer. FIG. 1 is a block diagram illustrating a configuration of an indirect transfer tandem laser printer. FIG. 3 is a plan view illustrating an example of a toner pattern used for color misregistration correction processing. FIG.

Explanation of symbols

4 Transfer section 51 Transfer body 108 Sensor 109 Temperature detection means TP Toner pattern

Claims (6)

Color misregistration correction that performs color misregistration correction processing that corrects the color misregistration of each color based on the information detected by the sensor by generating a toner pattern composed of multiple colors at the transfer unit and outputting it on the transfer body In a tandem type color image forming apparatus having means,
According to the maximum difference value that is the maximum between the colors among the difference values of the color misregistration amounts obtained for each number of repetitions of the toner pattern of each color other than the reference color detected during the color misregistration correction processing by the color misregistration correction unit. The number of times of output of the toner pattern in the next color misregistration correction process by the color misregistration correction means is set as the number of repetitions of the toner pattern when the maximum difference value is larger than a predetermined color misregistration correction allowable value. When the maximum difference value is smaller than the color misregistration correction allowable value, the first output count for changing the number of repetitions of the toner pattern to the minimum number of repetitions where the maximum difference value is less than the color misregistration correction allowable value. Comprising a changing means,
A color image forming apparatus. A temperature detecting means for detecting an apparatus internal temperature or an apparatus ambient temperature during the color misregistration correction processing by the color misregistration correcting means;
A temperature change detecting means for detecting a temperature change between the temperature detected by the temperature detecting means and the temperature at the previous color misregistration correction process;
Second output number changing means for changing the number of output times of the toner pattern in the color misregistration correction processing by the color misregistration correction means in accordance with the temperature change amount detected by the temperature change detecting means;
The color image forming apparatus according to claim 1, further comprising: An elapsed time measuring means for measuring an elapsed time from the color misregistration correction process by the previous color misregistration correction means;
Color misregistration correction by the color misregistration correction means according to the elapsed time from the previous color misregistration correction processing by the color misregistration correction means timed by the elapsed time timing means during the color misregistration correction processing by the color misregistration correction means. Second output number changing means for changing the number of output times of the toner pattern at the time of processing;
The color image forming apparatus according to claim 1, further comprising: Unit replacement detection means for detecting that a replacement unit that is detachable from the apparatus is replaced during the color misregistration correction processing by the color misregistration correction means;
When it is detected by the unit replacement detection means that the replacement unit has been replaced, the number of times of output of the toner pattern during the color misregistration correction processing by the color misregistration correction means is added to the maximum value or the current set value by a certain number of times. A second output number changing means for changing the value to
The color image forming apparatus according to claim 1, further comprising: The structure of the transfer part is a direct transfer system,
The color image forming apparatus according to claim 1, wherein the color image forming apparatus is a color image forming apparatus. The structure of the transfer part is an indirect transfer system.
The color image forming apparatus according to claim 1, wherein the color image forming apparatus is a color image forming apparatus.

Images