JP4884196B2 - Image processing apparatus, polygon motor control method, and control program - Google Patents

Description

  The present invention relates to an image processing apparatus for forming an image on a drum by a plurality of laser beams generated by different polygon motors, and more specifically, image processing for adjusting the phase of a polygon motor in these image processing apparatuses. The present invention relates to a device, a polygon motor control method using the device, and a control program therefor.

  2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus that scans a photosensitive drum and writes image information, an image processing apparatus that performs image transfer in synchronization with a plurality of print synchronization signals generated by a plurality of polygon motors has been used. Yes.

  Some recent image processing apparatuses form a single image using a plurality of laser beams and a plurality of polygon motors in order to improve the printing speed (for example, Patent Document 1). , 2).

  FIG. 8A is a block diagram for explaining a main configuration of a conventional image processing apparatus. The image processing apparatus includes an operation panel 101, a CPU 102, an image data input device 103, an image processing unit 104, a motor control circuit 105, a laser control circuit 106, an LSU (Laser Scanning Unit) 107, and a drum 108. The LSU 107 includes a polygon motor 107a and a laser diode 107b.

  The image processing apparatus starts operation by inputting a user instruction from the operation panel 101. The operation instruction information input to the operation panel 101 is converted into an operation instruction to each unit by the CPU 102 and transmitted to the image data input device 103, the image processing unit 104, the motor control circuit 105, and the laser control circuit 106.

The image data input device 103 is, for example, a scanner unit, a facsimile machine, a personal computer (PC), or the like. Image data input from the image data input device 103 is sent to the image processing unit 104.
The image processing unit 104 performs various types of image processing on the image data input from the image data input device 103. The image processing unit 104 converts input image data into a desired output, and converts the image data into an image suitable for output, such as image data density conversion and edge enhancement processing.

  The motor control circuit 105 controls the rotation of the polygon motor 107a by transmitting a control signal (motor clock). The polygon motor 107a rotates a polygon mirror for changing the angle of the laser beam from the laser diode 107b. The laser beam scans on the drum 108 as the polygon mirror rotates. The motor control circuit 105 creates a transfer synchronization signal based on the print synchronization signals 1 and 2 from the polygon motor 107 a and transmits it to the image processing unit 104.

The image processing unit 104 transmits the image data A 1 and A 2 to the laser control circuit 106 in synchronization with the transfer synchronization signal from the motor control circuit 105.
The laser control circuit 106 converts the image data A1 and A2 image-processed by the image processing unit 104 into laser signals. The image data B1 and B2 converted into laser signals are transferred to output paper via the drum 108.

An example of an image processing apparatus using a plurality of laser beams and a plurality of motors is shown in FIG. The image processing apparatus in this example includes _two polygon motors 107a ₁ and 107a ₂ , two laser diodes (LD) 107b ₁ and 107b ₂ , and two drums 108 ₁ and 108 ₂ . As described above, it is possible to improve the printing speed by forming a single image using a plurality of laser beams and a plurality of polygon motors.

  Here, when a plurality of polygon motors are used in the conventional image processing apparatus, the phase angles of the plurality of polygon motors are random, and the output timing of the print synchronization signal generated as the polygon motor rotates is synchronized. There wasn't.

  FIG. 9 is a diagram for explaining a print synchronization signal generated by a plurality of polygon motors. FIG. 9A shows image data A1 and A2 transferred according to the transfer synchronization signal, image data B1 transferred according to the print synchronization signal 1, and image data B2 transferred according to the print synchronization signal 2. Is shown.

  If the timings of the print synchronization signals 1 and 2 are not synchronized when the image data A1 and A2 are sent from the image processing unit 104, the image data B1 and B2 are line by line as shown in FIG. It will shift to. For this reason, as shown in FIGS. 9C and 9D, it is necessary to adjust the phase angle of the polygon motor so that the timings of the print synchronization signals 1 and 2 are output at the same timing.

  Some conventional motor frequency adjustment circuits adjust the phase difference by changing the rotation period of one of a plurality of polygon motors and making a difference in rotation speed with the other polygon motor. The polygon motor generates a print synchronization signal (BD) for each motor. The print synchronization signal indicates a synchronization timing indicating the laser print position with respect to the paper to be printed out. By outputting image data based on the print start synchronization signal, the print position on the paper can be made uniform.

  When a plurality of polygon motors are used, the phase relationship of the print start synchronization signal generated by each motor is indefinite immediately after startup. Some conventional image processing apparatuses adjust the phase of the print start synchronization signal by executing the following steps 1 to 3. This will be described with reference to FIG.

(Step 1) The phase difference between the print start synchronization signals is measured.
(Step 2) The rotation cycle of one polygon motor is changed. That is, the cycle of the print start synchronization signal changes. In the example of FIGS. 10A and 10B, at the time A, the rotation speed of the polygon motor is changed to a cycle B shorter than the cycle A.
(Step 3) The polygon motor rotation speed is changed for a certain time (period A in the examples of FIGS. 10A and 10B), and when the phase difference measured in Step 1 disappears, the polygon motor rotation speed is restored. Return to. In the example of FIGS. 10A and 10B, the rotational speed of the polygon motor is restored to the original at time B.

  FIG. 10C is a diagram showing a change in the cycle with respect to time. In the figure, time is taken on the horizontal axis, and the period is taken on the vertical axis. In this example, the period A is changed to a fixed period (period A) or a single period B (or period C or period D). . In the figure, the necessary hold time refers to a waiting time required until the next cycle change when the cycle change is performed a plurality of times in succession. The adjustment amount is a changeable amount of the cycle that is allowed by one cycle change, and differs depending on the polygon motor.

  FIG. 11A is a block diagram for explaining a configuration of an adjustment control unit that generates an adjustment cycle in the conventional apparatus. In the figure, reference numeral 109 denotes an adjustment control unit, which includes an initial phase difference / adjustment step 109a that outputs an adjustment time obtained by dividing the initial phase difference by an adjustment step (adjustment amount), an operation permission signal, and an adjustment time. The timer 109b that outputs the next cycle switching timing based on the adjustment time and the operation permission signal are received, and the adjustment cycle used for the adjustment is calculated based on the basic cycle, the adjustment step, and the cycle switching timing. A period generator 109c.

Thus, in the conventional configuration, when an operation permission signal is input, an adjustment cycle (here, cycle B) obtained by adding an adjustment step to the basic cycle is output as shown in FIG. This adjustment cycle (cycle B) is configured to return to the basic cycle when an adjustment time (period A), which is the result of dividing the initial phase difference by the adjustment step, has elapsed.
JP-A-11-208026 JP 2000-241740 A

  However, if the period of the polygon motor is changed abruptly in the procedure of step 1 described above, the rotation of the polygon motor becomes unstable and becomes uncontrollable. Therefore, the change range of the motor period is within a range where stable rotation of the motor is possible. Need to be restricted. As a result, there is a problem in that the change range of the motor cycle is limited and the adjustment time becomes long.

  The present invention has been made in view of the above circumstances, and is an image processing apparatus capable of adjusting the phase difference between motors by changing the motor cycle a plurality of times while stably maintaining the rotational state of the polygon motor. It is an object of the present invention to provide a polygon motor control method and a control program using the apparatus.

In order to solve the above-described problem, a first technical means of the present invention is used in an electrophotographic image forming apparatus that scans a photosensitive drum and writes image information, and a plurality of polygon motors generated by a plurality of polygon motors. An image processing apparatus for transferring an image in synchronization with a print synchronization signal, which shows a phase generation unit for generating a motor clock for controlling a rotation cycle of a polygon motor and a phase state of the polygon motor output from each polygon motor a phase difference measuring section for measuring the phase difference of the printing synchronization signals, based on the phase difference measured by the phase difference measuring unit, after successively adding or subtracting a plurality of times the rotation period of one of the polygon motor, continuously an adjustment controller for adjusting a phase difference between the other of the polygon motor by multiple subtraction or addition, to stably hold the rotating state of one of the polygon motor Or an adjustment tolerance measuring means for measuring the adjustment tolerance of the modulatable period adjustment control unit, half of the initial phase difference immediately after one of the polygon motor start, already phase adjustment already been adjusted A comparison means for comparing the amount, and when adjusting the rotation period of one polygon motor based on the comparison result of the comparison means, the adjustment amount of the rotation period is set according to the adjustment allowable amount of one polygon motor. It is characterized by changing .

The second technical means is used in an electrophotographic image forming apparatus that scans a photosensitive drum and writes image information, and performs image transfer in synchronization with a plurality of print synchronization signals generated by a plurality of polygon motors. A phase difference measurement unit for measuring a phase difference between a cycle generation unit that generates a motor clock for controlling a rotation cycle of a polygon motor and a print synchronization signal indicating a phase state of the polygon motor output from each polygon motor. Based on the phase difference measured by the measurement unit and the phase difference measurement unit, the polygon cycle of one polygon motor is continuously added or subtracted multiple times, and then the other polygon is subtracted or added multiple times continuously. An adjustment control unit that adjusts the phase difference with the motor, and an adjustment allowance for the period that can be modulated while keeping the rotational state of one polygon motor stable. The adjustment control unit includes a comparison unit that compares ½ of the initial phase difference immediately after starting one of the polygon motors with the already adjusted phase adjustment amount. When adjusting the phase difference by switching between addition and subtraction of the rotation cycle of one polygon motor based on the comparison result of the means, the adjustment amount of the rotation cycle is changed according to the adjustment allowable amount of one polygon motor. It is characterized by that.

The third technical means is used in an electrophotographic image forming apparatus that scans a photosensitive drum and writes image information, and performs image transfer in synchronization with a plurality of print synchronization signals generated by a plurality of polygon motors. A phase difference measurement unit for measuring a phase difference between a cycle generation unit that generates a motor clock for controlling a rotation cycle of a polygon motor and a print synchronization signal indicating a phase state of the polygon motor output from each polygon motor. Based on the phase difference measured by the measurement unit and the phase difference measurement unit, the polygon cycle of one polygon motor is continuously added or subtracted multiple times, and then the other polygon is subtracted or added multiple times continuously. Adjustment control unit that adjusts the phase difference from the motor, and the next cycle change necessary to keep the rotation state of one polygon motor stable A required hold time measuring means for measuring the yield time, and the adjustment control unit compares the half of the initial phase difference immediately after starting one of the polygon motors with the already adjusted phase adjustment amount. When adjusting the rotation cycle of one polygon motor based on the comparison result of the comparison means, the hold time until the next cycle change is changed according to the required hold time of one polygon motor. It is a feature.

A fourth technical means is used in an electrophotographic image forming apparatus that scans a photosensitive drum and writes image information, and performs image transfer in synchronization with a plurality of print synchronization signals generated by a plurality of polygon motors. A phase difference measurement unit for measuring a phase difference between a cycle generation unit that generates a motor clock for controlling a rotation cycle of a polygon motor and a print synchronization signal indicating a phase state of the polygon motor output from each polygon motor. Based on the phase difference measured by the measurement unit and the phase difference measurement unit, the polygon cycle of one polygon motor is continuously added or subtracted multiple times, and then the other polygon is subtracted or added multiple times continuously. Adjustment control unit that adjusts the phase difference from the motor, and the next cycle change necessary to keep the rotation state of one polygon motor stable A required hold time measuring means for measuring the yield time, and the adjustment control unit compares the half of the initial phase difference immediately after starting one of the polygon motors with the already adjusted phase adjustment amount. When the phase difference is adjusted by switching between addition and subtraction of the rotation period of one polygon motor based on the comparison result of the comparison means, the next period is changed according to the required hold time of one polygon motor. The hold time until is changed .

A fifth technical means is used in an electrophotographic image forming apparatus that scans a photosensitive drum and writes image information, and performs image transfer in synchronization with a plurality of print synchronization signals generated by a plurality of polygon motors. A polygon motor control method by an image processing apparatus, wherein a phase difference measurement step for measuring a phase difference of a print synchronization signal indicating a phase state of a polygon motor output from each polygon motor, and a phase difference measured in a phase difference measurement step An adjustment control step for adjusting the phase difference with the other polygon motor by continuously adding or subtracting the rotation period of one polygon motor a plurality of times and then subtracting or adding a plurality of times continuously. The adjustment control step includes one half of the initial phase difference immediately after starting one of the polygon motors and the already adjusted phase adjustment amount. The following period necessary for stably maintaining the rotation state of one polygon motor when adjusting the rotation period of one polygon motor based on the comparison result in the comparison step The hold time until the next cycle change is changed according to the result of measuring the required hold time until the change .

A sixth technical means is used in an electrophotographic image forming apparatus that scans a photosensitive drum and writes image information, and performs image transfer in synchronization with a plurality of print synchronization signals generated by a plurality of polygon motors. A polygon motor control method by an image processing apparatus, wherein a phase difference measurement step for measuring a phase difference of a print synchronization signal indicating a phase state of a polygon motor output from each polygon motor, and a phase difference measured in a phase difference measurement step An adjustment control step for adjusting the phase difference with the other polygon motor by continuously adding or subtracting the rotation period of one polygon motor a plurality of times and then subtracting or adding a plurality of times continuously. The adjustment control step includes one half of the initial phase difference immediately after starting one of the polygon motors and the already adjusted phase adjustment amount. A comparison step, and based on the comparison result in the comparison step, when the phase difference is adjusted by switching the addition or subtraction of the rotation period of one polygon motor, the rotation state of one polygon motor is stabilized. The hold time until the next cycle change is changed in accordance with the result of measuring the required hold time until the next cycle change necessary for holding .

The seventh technical means is a control program for causing a computer to execute the polygon motor control method in the fifth or sixth technical means.

  According to the present invention, the phase difference between the motors can be adjusted by changing the motor cycle a plurality of times while maintaining the rotation state of the polygon motor stably, so that each beam of image data formed by each laser beam can be adjusted. In addition to preventing the occurrence of deviation, the adjustment time can be shortened as compared with the case of adjusting in a single cycle.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of an image processing device, a polygon motor control method, and a control program according to the invention will be described with reference to the accompanying drawings. In addition, the description which abbreviate | omitted the element which attached | subjected the same code | symbol in drawing has the same function, and is abbreviate | omitted.

  FIG. 1A is a block diagram illustrating a configuration example of a main part of an image processing apparatus according to an embodiment of the present invention. The image processing apparatus includes a motor control circuit 1 that controls rotation of a polygon motor, a CPU 6 that controls the entire apparatus, and LSUs 7 and 8 that drive the polygon motor and scan a laser beam on a drum.

  The LSU 7 includes a polygon motor 7a and a photodiode 7b, and the LSU 8 includes a polygon motor 8a and a photodiode 8b. The motor control circuit 1 adjusts the phase difference with the other polygon motor 7a by continuously adding or subtracting the rotation cycle of one polygon motor 8a a plurality of times and then continuously subtracting or adding a plurality of times. The control unit 2, the phase difference measuring unit 3 for measuring the phase difference between the print synchronization signals 1 and 2 indicating the phase states of the polygon motors output from the polygon motors 7a and 8a, and the rotation cycles of the polygon motors 7a and 8a. Period generators 4 and 5 that generate motor clocks to be controlled. The adjustment control unit 2 adjusts the rotation period of the polygon motor 8 a based on the phase difference measured by the phase difference measurement unit 3.

In the case of the present embodiment, the polygon motor 7a is driven with a basic cycle via the cycle generator 4, and the polygon motor 8a is driven with an adjustment cycle via the cycle generator 5.
The adjustment control unit 2 generates an adjustment cycle for output to the cycle generation unit 5. It operates according to the operation permission signal from the CPU 6, modulates the basic period based on the period adjustment amount and the necessary hold time, and outputs it as the adjustment period. The period adjustment amount is a changeable amount of the period that is allowed by one period change, and differs depending on the polygon motor. If the cycle is rapidly changed beyond the cycle adjustment amount, the rotation state of the polygon motor becomes unstable. The necessary hold time is a waiting time required until the next cycle change when the cycle change is performed a plurality of times in succession. If the cycle is continuously changed without waiting for the necessary hold time, the rotational state of the polygon motor becomes unstable.

  The adjustment control unit 2 in the present embodiment makes it possible to shorten the phase adjustment time by changing the cycle a plurality of times while keeping the rotation state of the polygon motor stable. A detailed configuration example of the adjustment control unit 2 will be described later.

  The phase difference measuring unit 3 measures the phase difference between the print synchronization signals 1 and 2 output from the polygon motors 7a and 8a. That is, as shown in FIG. 1B, the phase difference between the print synchronization signals 1 and 2 output from the polygon motors 7a and 8a is measured and output to the adjustment control unit 2.

  The cycle generators 4 and 5 generate motor clocks that serve as references for the rotational operations of the polygon motors 7a and 8a, respectively. Based on the period information preset by the CPU 6, a motor clock having a constant period is output. The motor clock 1 output from the cycle generation unit 4 is a clock generated with a basic cycle, and the motor clock 2 output from the cycle generation unit 5 is a clock generated with an adjustment cycle. By giving the motor clock 2 a period different from that of the motor clock 1, a difference occurs in the rotation periods of the polygon motor 7a and the polygon motor 8a, and the phase difference can be adjusted.

FIG. 2A is a block diagram illustrating a detailed configuration example of the adjustment control unit 2 illustrated in FIG. The adjustment control unit 2 includes a hold time timer 21, an adjustment timing generator 22, and a period generator 23.
The hold time timer 21 is a timer that measures the next time when the cycle can be changed while maintaining the rotation stability of the polygon motor 8a after changing the cycle with respect to the basic cycle. The hold time timer 21 outputs a cycle switching timing every time the necessary hold time elapses after receiving the operation permission signal.

  The adjustment timing generator 22 generates adjustment timing. That is, the adjustment timing generator 22 adds an adjustment step (period adjustment amount), a period switching timing, an initial phase difference, a necessary hold time, and an operation permission signal, and adds the period adjustment direction (previous period). , Subtract) or an adjustment permission signal. A detailed configuration example of the adjustment timing generator 22 will be described later.

  The period generator 23 calculates an adjustment period used for adjustment. That is, the cycle generator 23 calculates the adjustment cycle from the basic cycle, the adjustment step, the cycle switching timing, the adjustment direction, and the adjustment permission signal. The cycle generator 23 adds or subtracts the cycle for the adjustment step with respect to the current adjustment cycle every time the cycle switching timing is input. Which of the addition and subtraction processes is selected is determined according to the control signal in the adjustment direction. The control signal in the adjustment direction is generated by the adjustment timing generator 22 and is switched at the timing when the phase adjustment of half of the initial phase difference is completed.

  FIG. 2B is a diagram illustrating an example of a change in the motor cycle with respect to time based on the configuration of the adjustment control unit 2 illustrated in FIG. In the figure, the vertical axis represents the rotation period of the polygon motor, the horizontal axis represents time, and the period is changed stepwise from the basic period to the adjustment period A, thereafter from period A to period B, and from period B to period C. Show the state. As described above, the cycle generator 23 adds or subtracts the cycle for the adjustment step with respect to the current adjustment cycle every time the cycle switching timing is input. As a result, since the cycle can be adjusted a plurality of times in a stepwise manner, the phase adjustment time can be shortened as compared with the case where adjustment is performed in a single cycle.

  FIG. 3A is a block diagram illustrating a detailed configuration example of the adjustment timing generator 22 illustrated in FIG. The adjustment timing generator 22 includes a multiplier 221, an adder 222, a latch 223, a divider 224, and two comparators 224 and 226. The phase adjustment amount (sum) is calculated by the following equation (1) by the combination of the multiplier 221, the adder 222, and the latch 223.

      Phase adjustment amount (sum) = Σ adjustment step × required hold time (1)

  The divider 224 calculates the folded phase difference. That is, the divider 224 divides the initial phase difference by “2” to calculate the return phase difference for switching the adjustment calculation direction of the adjustment period.

Comparator 225 corresponds to the comparison means of the present invention, and a turn-back phase difference that is ½ of the initial phase difference immediately after the polygon motor is started, and a phase adjustment amount (total) that has already been adjusted. And the adjustment direction switching signal is reversed when the phase adjustment amount (sum) exceeds the return phase difference. In other words, if addition adjustment is performed, subtraction is performed, and if subtraction adjustment is performed, addition is performed reverse.
The comparator 226 compares the phase adjustment amount (total) with the initial phase difference, and stops the output of the adjustment permission signal when the phase adjustment amount (total) exceeds the initial phase difference, and outputs the adjustment stop signal. To do.

  With the above configuration, the return phase difference (1/2 of the initial phase difference) and the phase adjustment amount (total) are compared, and the adjustment direction (addition or subtraction) is completed at the timing when the adjustment of 1/2 of the initial phase difference is completed. Can be switched. Also, the phase adjustment process can be completed at the timing when the adjustment of the initial phase difference is completed by comparing the initial phase difference and the phase adjustment amount (total).

  FIG. 3B is a diagram showing an example of how the motor cycle changes with time based on the configuration of the adjustment timing generator 22 shown in FIG. In the figure, the vertical axis represents the rotation period of the polygon motor, the horizontal axis represents time, and the basic period is changed to the adjustment periods A, B, and C in stages. First, an adjustment step A is added to the basic period at the period switching timing to generate an adjustment period A. When the necessary hold time elapses, the adjustment period A is added to the adjustment period A at the period switching timing to generate the adjustment period B. Similarly, an adjustment cycle C is generated.

  Next, the return phase difference (1/2 of the initial phase difference) is compared with the phase adjustment amount (total), and the adjustment direction is switched at the timing when the adjustment of 1/2 of the initial phase difference is completed. In this example, switching is performed from addition to subtraction at the adjustment direction switching time. Then, as in the addition, the adjustment cycle is changed step by step, the initial phase difference is compared with the phase adjustment amount (total), and the original phase difference adjustment is completed (adjustment end timing). The phase is returned to the basic period and the phase adjustment process is terminated.

  Here, a fraction may occur at the adjustment end timing when the adjustment ends. As countermeasures in this case, first, the adjustment step is reduced and the second adjustment is performed. Second, the turning point is calculated before the adjustment is started, and the adjustment step and the cycle switching timing are generated accordingly. Can be considered. In the case of this embodiment, the turning point for switching the rotation cycle from increase to decrease or from decrease to increase can be optimized (in this example, 1/2 of the initial phase difference), so overrun and underrun occur at the end of adjustment. There is nothing to do.

  As described above, according to the image processing apparatus of the present invention, a single image is formed using a plurality of laser beams generated by a plurality of polygon motors, and the period of the polygon motor is continuously added or subtracted a plurality of times. After that, by adjusting the phase of the polygon motor by subtracting or adding a plurality of times in succession, it is possible to prevent the deviation of the image data formed by each laser beam for each beam. Furthermore, the initial phase difference when the polygon motor is started is measured, this initial phase difference, the amount of adjustment that can be changed while maintaining stable rotation of the polygon motor, and the next adjustment after the completion of one phase adjustment. It is possible to calculate the optimum time for switching the cycle from increase to decrease or from decrease to increase from the required hold (waiting) time of the motor required for.

  FIG. 4A is a block diagram illustrating a configuration example of an image processing apparatus according to another embodiment of the present invention. The image processing apparatus includes a motor control circuit 1, a CPU 6, an LSU 7, an operation panel 9, an image data input device 10, an image processing unit 11, a laser control circuit 12, a drum 13, and an adjustment allowable amount measurement circuit 14. The LSU 7 includes a plurality of polygon motors and a plurality of laser diodes.

  The image processing apparatus according to the present embodiment starts an operation by inputting a user instruction from the operation panel 9. The operation instruction information input to the operation panel 9 is converted into an operation instruction to each unit by the CPU 6 and transmitted to the image data input device 10, the image processing unit 11, the motor control circuit 1, and the laser control circuit 12.

The image data input device 10 is, for example, a scanner unit, a facsimile machine, a personal computer (PC), or the like. The image data input from the image data input device 10 is sent to the image processing unit 11.
The image processing unit 11 performs various types of image processing on the image data input from the image data input device 10. The image processing unit 11 converts input image data into a desired output, and converts the image data into an image suitable for output, such as image data density conversion or edge enhancement processing.

  The motor control circuit 1 transmits a control signal (motor clock) and controls the rotation of the polygon motor included in the LSU 7. The motor control circuit 1 creates a transfer synchronization signal based on the print synchronization signals 1 and 2 from the polygon motor, and transmits the transfer synchronization signal to the image processing unit 11.

The image processing unit 11 transmits the image data A 1 and A 2 to the laser control circuit 12 in synchronization with the transfer synchronization signal from the motor control circuit 1.
The laser control circuit 12 converts the image data A1 and A2 image-processed by the image processing unit 11 into laser signals. The image data B1 and B2 converted into laser signals are transferred to output paper via the drum 13.

  The adjustment allowance measuring circuit 14 corresponds to the adjustment allowance measuring means of the present invention, and measures the adjustment allowance of a period that can be modulated while keeping the rotation state of the polygon motor stable. The adjustment amount of the rotation period is changed according to the adjustment allowable amount of the polygon motor. That is, the adjustment allowable amount measurement circuit 14 generates an adjustment period from the adjustment amount set in advance by the CPU 6 and observes the rotation state of the polygon motor. The rotation state of the polygon motor can be detected by observing a motor lock error signal output from the motor. The adjustment allowable amount measurement circuit 14 measures the motor lock error signal by exchanging the adjustment amounts (adjustment amounts 1, 2, and 3) multiple times. The maximum adjustment amount that does not cause a motor lock error is set as an adjustment allowable amount. The adjustment allowable amount measurement circuit 14 outputs the measured adjustment allowable amount or the adjustment cycle generated from the adjustment allowable amount to the motor control circuit 1.

  In the case of the present embodiment, as shown in FIG. 4B, adjustment amounts 1, 2, and 3 are set in advance in the CPU 6, and each adjustment period is generated from these. Then, as shown in FIG. 4C, the occurrence of a motor lock error is observed when the adjustment cycles are 1, 2, and 3. Here, since the motor lock error has occurred when the adjustment cycle is 3, the adjustment amount 2 corresponding to the adjustment cycle 2 is the maximum adjustment amount, and this is the adjustment allowable amount.

  FIG. 5A is a block diagram illustrating a configuration example of an image processing apparatus according to another embodiment of the present invention. The image processing apparatus includes a motor control circuit 1, a CPU 6, an LSU 7, an operation panel 9, an image data input device 10, an image processing unit 11, a laser control circuit 12, a drum 13, and a necessary hold time measurement circuit 15. The LSU 7 includes a plurality of polygon motors and a plurality of laser diodes.

  The necessary hold time measuring circuit 15 corresponds to the necessary hold time measuring means of the present invention, and measures the necessary hold time which is the minimum waiting time until the next period change in order to keep the rotation state of the polygon motor stable. . The hold time until the next cycle change is changed according to the required hold time of the polygon motor. That is, the necessary hold time measurement circuit 15 generates an adjustment period from the hold time set in advance by the CPU 6 and observes the rotation state of the polygon motor. The adjustment hold time measurement circuit 15 switches the hold times (hold times 1, 2, 3) a plurality of times and measures the motor lock error signal. The minimum hold time in which no motor lock error occurs is set as the required hold time. The necessary hold time measurement circuit 15 outputs the measured necessary hold time or an adjustment cycle generated from the necessary hold time to the motor control circuit 1.

  In the present embodiment, hold times 1, 2, and 3 are set in advance in the CPU 6 with respect to the adjustment cycle including the hold time shown in FIG. 5B, and each adjustment cycle is generated from these. Then, as shown in FIG. 5C, for example, when the hold times 1, 2, and 3 are shortened in this order, the occurrence of a motor lock error is observed at the time of the hold time 3. In this case, the hold time 2 immediately before is the minimum hold time, and this is the necessary hold time.

  FIG. 6 is a flowchart for explaining an example of a polygon motor control method by the image processing apparatus of the present invention. First, the image processing apparatus measures the initial phase difference of the print synchronization signal indicating the phase state of the polygon motor output from each polygon motor (step S1), and calculates the adjustment direction switching time (step S2). This adjustment direction switching time is a time when the sum of the phase adjustment amounts obtained by the above-described equation (1) is larger than ½ of the initial phase difference.

  Next, the image processing apparatus compares the adjustment direction switching time with the current time indicated by the timer (step S3). As a result of the comparison, if adjustment direction switching time> current time (in the case of YES), it is determined whether the necessary hold time has elapsed (step S4). If the necessary hold time has elapsed (in the case of YES), the adjustment cycle is set. Increase by the adjustment step (step S5). In step S4, if the necessary hold time has not elapsed (in the case of NO), the process waits until the necessary hold time elapses.

  On the other hand, as a result of the comparison in step S3, if adjustment direction switching time <current time (in the case of NO), it is determined whether the necessary hold time has elapsed (step S6), and if the necessary hold time has elapsed (in the case of YES) ), The adjustment cycle is decreased by the adjustment step (step S7). In step S6, if the necessary hold time has not elapsed (in the case of NO), the process waits until the necessary hold time elapses.

  Then, the image processing apparatus compares the current time with the adjustment end time (step S8), and if the adjustment end time <the current time (in the case of NO), the image processing apparatus ends the process. On the other hand, if adjustment end time> current time (in the case of YES), the process returns to step S3 to compare the adjustment direction switching time with the current time. Note that the adjustment end time is the time when the sum of the phase adjustment amounts obtained by the above equation (1) becomes larger than the initial phase difference.

  FIG. 7 is a flowchart for explaining another example of the polygon motor control method by the image processing apparatus of the present invention. Here, the adjustment end time calculation process in step S8 shown in FIG. 6 will be described. First, the image processing apparatus determines whether or not the sum of the phase adjustment amounts obtained by the above equation (1) is larger than the initial phase difference (step S11), and the sum of the phase adjustment amounts is smaller than the initial phase difference. If (NO), a new phase adjustment amount (adjustment step × required hold time) is calculated (step S12). Then, the sum of the phase adjustment amounts (the sum of the already adjusted phase adjustment amounts + the new phase adjustment amount) is updated (step S13), and the process returns to step S11 to repeat the process.

  Then, in step S11, when the sum of the phase adjustment amounts is larger than the initial phase difference (in the case of YES), the image processing apparatus sets the time at that time as the adjustment end time (step S14).

  As described above, each embodiment has been described centering on each function in the image processing apparatus of the present invention. However, the present invention is a form as a polygon motor control method as described also as a method for executing each step in the image processing apparatus. I can take it. Similarly to the image processing apparatus having each function, a form as a control program for causing a computer to execute the polygon motor control method and a form as a recording medium on which the control program is recorded are possible.

  An embodiment of a recording medium storing a control program and data for executing a polygon motor control method according to the present invention will be described. Specific recording media include CD-ROM (-R / -RW), magneto-optical disk, DVD-ROM (-R / -RW / -RAM), FD, HD, BD, flash memory, memory card. In addition, memory sticks and other various ROMs, RAMs, and the like can be assumed. By recording and distributing the control program for causing the computer to execute the polygon motor control method of the present invention described above on these recording media, the method can be executed. To make it easier. Then, mount the recording medium as described above on an image processing apparatus such as a computer and read the control program by the image processing apparatus, or store the control program in a storage medium provided in the image processing apparatus, and By reading in response, the polygon motor control method according to the present invention can be executed.

As described above, according to the present invention, the initial phase difference at the time of starting the polygon motor, the adjustment amount of the period that can be modulated while maintaining the stable rotation of the polygon motor, and the stable rotation of the polygon motor are maintained. From the required hold time required until the next cycle adjustment, the phase difference between the motors is adjusted by changing the cycle multiple times while keeping the motor cycle change range within the range where stable motor rotation is possible. Therefore, it is possible to prevent the occurrence of deviation for each beam of image data formed by each laser beam, and to shorten the adjustment time as compared with the case where adjustment is performed in a single cycle.
In addition, when changing the motor cycle multiple times, it is possible to calculate the optimal time for switching the motor cycle from increase to decrease, or from decrease to increase, so overrun and underrun may occur at the end of phase adjustment. Absent.

1 is a block diagram illustrating a configuration example of a main part of an image processing apparatus according to an embodiment of the present invention. It is a block diagram which shows the detailed structural example of the adjustment control part shown to FIG. 1 (A). It is a block diagram which shows the detailed structural example of the adjustment timing generator shown to FIG. 2 (A). It is a block diagram which shows the structural example of the image processing apparatus which concerns on other embodiment of this invention. It is a block diagram which shows the structural example of the image processing apparatus which concerns on other embodiment of this invention. It is a flowchart for demonstrating an example of the polygon motor control method by the image processing apparatus of this invention. It is a flowchart for demonstrating the other example of the polygon motor control method by the image processing apparatus of this invention. It is a block diagram for demonstrating the principal part structure of the conventional image processing apparatus. It is a figure for demonstrating the printing synchronous signal which a some polygon motor produces | generates. It is a figure for demonstrating the method to match | combine the phase of a printing start synchronizing signal in a conventional apparatus. It is a block diagram for demonstrating the structure of the adjustment control part which produces | generates an adjustment period in a conventional apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,105 ... Motor control circuit, 2 ... Adjustment control part, 3 ... Phase difference measurement part, 4, 5 ... Period generation part, 6,102 ... CPU, 7, 8, 107 ... LSU, 7a, 8a, 107a ... Polygon Motor, 7b, 8b, 107b ... Photodiode, 9, 101 ... Operation panel, 10, 103 ... Image data input device, 11, 104 ... Image processing unit, 12, 106 ... Laser control circuit, 13, 108 ... Drum, 14 ... Adjustment allowance measurement circuit, 15 ... Necessary hold time measurement circuit, 21 ... Hold time timer, 22 ... Adjustment timing generator, 23 ... Period generator, 221 ... Multiplier, 222 ... Adder, 223 ... Latch, 224 ... Divider, 225, 226... Comparator.

Claims (7)

An image processing apparatus that is used in an electrophotographic image forming apparatus that scans a photosensitive drum and writes image information, and performs image transfer in synchronization with a plurality of print synchronization signals generated by a plurality of polygon motors,
A cycle generator for generating a motor clock for controlling the rotation cycle of the polygon motor;
A phase difference measuring unit for measuring a phase difference of a print synchronization signal indicating a phase state of the polygon motor output from each polygon motor;
Based on the phase difference measured by the phase difference measuring unit, the rotation period of one of the polygon motors is continuously added or subtracted a plurality of times , and then the other polygon motor is continuously subtracted or added a plurality of times. an adjustment controller for adjusting a phase difference between,
An adjustment tolerance measuring means for measuring an adjustment tolerance of a period capable of modulation while stably maintaining the rotation state of the one polygon motor ,
The adjustment control unit includes a comparison unit that compares 1/2 of the initial phase difference immediately after the one of the polygon motors is activated with the already adjusted phase adjustment amount.
When adjusting the rotation cycle of the one polygon motor based on the comparison result of the comparison means, the adjustment amount of the rotation cycle is changed according to the adjustment allowable amount of the one polygon motor. An image processing apparatus. An image processing apparatus that is used in an electrophotographic image forming apparatus that scans a photosensitive drum and writes image information, and performs image transfer in synchronization with a plurality of print synchronization signals generated by a plurality of polygon motors,
A cycle generator for generating a motor clock for controlling the rotation cycle of the polygon motor;
A phase difference measuring unit for measuring a phase difference of a print synchronization signal indicating a phase state of the polygon motor output from each polygon motor;
Based on the phase difference measured by the phase difference measuring unit, the rotation period of one of the polygon motors is continuously added or subtracted a plurality of times, and then the other polygon motor is continuously subtracted or added a plurality of times. An adjustment control unit for adjusting the phase difference between and
An adjustment tolerance measuring means for measuring an adjustment tolerance of a period capable of modulation while stably maintaining the rotation state of the one polygon motor,
The adjustment control unit includes a comparison unit that compares 1/2 of the initial phase difference immediately after the one of the polygon motors is activated with the already adjusted phase adjustment amount.
Based on the comparison result of the comparison means, when the phase difference is adjusted by switching between addition and subtraction of the rotation period of the one polygon motor, the rotation period of the one polygon motor is adjusted according to the adjustment allowable amount of the one polygon motor. An image processing apparatus characterized by changing an adjustment amount . An image processing apparatus that is used in an electrophotographic image forming apparatus that scans a photosensitive drum and writes image information, and performs image transfer in synchronization with a plurality of print synchronization signals generated by a plurality of polygon motors,
A cycle generator for generating a motor clock for controlling the rotation cycle of the polygon motor;
A phase difference measuring unit for measuring a phase difference of a print synchronization signal indicating a phase state of the polygon motor output from each polygon motor;
Based on the phase difference measured by the phase difference measuring unit, the rotation period of one of the polygon motors is continuously added or subtracted a plurality of times, and then the other polygon motor is continuously subtracted or added a plurality of times. An adjustment control unit for adjusting the phase difference between and
A necessary hold time measuring means for measuring a necessary hold time until the next cycle change necessary for stably maintaining the rotation state of the one polygon motor,
The adjustment control unit includes a comparison unit that compares 1/2 of the initial phase difference immediately after the one of the polygon motors is activated with the already adjusted phase adjustment amount.
When adjusting the rotation cycle of the one polygon motor based on the comparison result of the comparison means, the hold time until the next cycle change is changed according to the required hold time of the one polygon motor. A featured image processing apparatus. An image processing apparatus that is used in an electrophotographic image forming apparatus that scans a photosensitive drum and writes image information, and performs image transfer in synchronization with a plurality of print synchronization signals generated by a plurality of polygon motors,
A cycle generator for generating a motor clock for controlling the rotation cycle of the polygon motor;
A phase difference measuring unit for measuring a phase difference of a print synchronization signal indicating a phase state of the polygon motor output from each polygon motor;
Based on the phase difference measured by the phase difference measuring unit, the rotation period of one of the polygon motors is continuously added or subtracted a plurality of times, and then the other polygon motor is continuously subtracted or added a plurality of times. An adjustment control unit for adjusting the phase difference between and
A necessary hold time measuring means for measuring a necessary hold time until the next cycle change necessary for stably maintaining the rotation state of the one polygon motor,
The adjustment control unit includes a comparison unit that compares 1/2 of the initial phase difference immediately after the one of the polygon motors is activated with the already adjusted phase adjustment amount.
Based on the comparison result of the comparison means, when the phase difference is adjusted by switching between addition and subtraction of the rotation period of the one polygon motor, the next period is changed according to the required hold time of the one polygon motor. An image processing apparatus characterized in that the hold time until is changed . Polygon motor control by an image processing apparatus that is used in an electrophotographic image forming apparatus that scans a photosensitive drum and writes image information, and performs image transfer in synchronization with a plurality of print synchronization signals generated by a plurality of polygon motors A method,
A phase difference measuring step for measuring a phase difference of a print synchronization signal indicating a phase state of the polygon motor output from each of the polygon motors;
Based on the phase difference measured in the phase difference measuring step, the rotation period of one of the polygon motors is continuously added or subtracted a plurality of times, and then the other polygon motor is continuously subtracted or added a plurality of times. And an adjustment control step for adjusting the phase difference between and
The adjustment control step includes a comparison step of comparing ½ of the initial phase difference immediately after starting the one polygon motor and the already adjusted phase adjustment amount.
Based on the comparison result in the comparison step, when adjusting the rotation cycle of the one polygon motor, the necessary hold until the next cycle change necessary to stably hold the rotation state of the one polygon motor. A polygon motor control method comprising: changing a hold time until the next cycle change according to a result of measuring the time . Polygon motor control by an image processing apparatus that is used in an electrophotographic image forming apparatus that scans a photosensitive drum and writes image information, and performs image transfer in synchronization with a plurality of print synchronization signals generated by a plurality of polygon motors A method,
A phase difference measuring step for measuring a phase difference of a print synchronization signal indicating a phase state of the polygon motor output from each of the polygon motors;
Based on the phase difference measured in the phase difference measuring step, the rotation period of one of the polygon motors is continuously added or subtracted a plurality of times, and then the other polygon motor is continuously subtracted or added a plurality of times. And an adjustment control step for adjusting the phase difference between and
The adjustment control step includes a comparison step of comparing ½ of the initial phase difference immediately after starting the one polygon motor and the already adjusted phase adjustment amount.
Necessary for stably maintaining the rotation state of the one polygon motor when adjusting the phase difference by switching the addition / subtraction of the rotation period of the one polygon motor based on the comparison result in the comparison step. A polygon motor control method comprising: changing a hold time until the next cycle change according to a result of measuring a required hold time until the next cycle change . A control program for causing a computer to execute the polygon motor control method according to claim 5 .

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