JP5407297B2 - Motor control device, motor control method, and image forming apparatus - Google Patents

Description

  The present invention relates to a motor control device, a motor control method, and an image forming apparatus that control a motor driver based on a rotation output signal output by rotation of a motor driven by the motor driver.

  2. Description of the Related Art Conventionally, as an image forming apparatus, a copy function, a facsimile (FAX) function, a print function, a scanner function, and a function of distributing an input image (an original image read by a scanner function or an image input by a printer or a FAX function) are provided. In addition, in an MFP (Multi Function Peripheral), high-precision motor control is required. For example, when the rotational speed of the intermediate transfer motor that drives the intermediate transfer belt changes, there are problems such as color misregistration and image distortion. For this reason, in the intermediate transfer belt, the motor is controlled so as to maintain the target speed based on the difference between the rotation output signal output by the rotation of the motor and the target speed signal.

  However, in motor control based on the difference between the motor rotation output signal and the target speed signal, control is performed with the resolution of the motor rotation output signal, so the cycle of the motor rotation output signal is too large, and high-precision control is possible. There was no problem.

  Therefore, in Patent Document 1, the accuracy of control is improved by providing a timer 1107 having a frequency higher than the frequency of the rotation output signal SG1001 (encoder pulse). Here, the prior art will be described with reference to FIGS. FIG. 13 is a functional block diagram showing the motor control device of Patent Document 1. As shown in FIG.

  In FIG. 13, when the rotation output signal SG1001 is output by the rotation of the motor 1021, the input capture 1101 (HSI unit: High-Speed Interconnect: high-speed input) indicates that the rotation output signal SG1001 rises to the free-run timer 1107 (timer ) Is stored in a memory (FIFO: First-In, First-Out) 1111. Here, the free-run timer 1107 has a sufficiently higher frequency than the rotation output signal SG1001.

A CPU (Central Processing Unit) 1110 is interrupted by a software timer at the end of a predetermined sampling period. When the CPU 1110 receives the interrupt, the CPU 1110 uses the value stored in the memory 1111 and the timer value interrupted from the leading edge of the previous rotation output signal SG1001 to calculate the rotation output signal SG1001 (encoder pulse) during the sampling period. Calculate the average frequency. Further, the CPU 1110 calculates a speed control instruction value D1004 (encoder feedback instruction value) of the motor 1021 output to a PWM (Pulse Width Modulation) timer 1104 (pulse width modulation unit) using the average frequency. By driving the motor 1021 based on the speed control instruction value D1004, higher-precision control than the conventional one is realized.
Japanese Unexamined Patent Publication No. 04-255867

  However, in the invention of Patent Document 1, the control period signal timing (interrupt timing) is considered, but the time until the speed control instruction value D1004 is reflected in the output PWM signal SG1006 to the motor driver 1105 is not considered. This problem will be described with reference to FIG.

  FIG. 14 is a graph schematically showing the relationship between the time required for reflecting the speed control instruction value D1004 to the PWM signal SG1006 and the speed change. As shown in FIG. 14, when the rotational speed of the motor is gradually increased, there is a difference between the speed used for the instruction value calculation and the actual speed, so that the precise control cannot be performed. There is. Furthermore, if it takes time to calculate the speed control instruction value D1004 due to the load of the CPU 1110 and the like, and it takes time for the PWM timer 1104 to reflect the speed control instruction value D1004 in the PWM signal SG1006, the speed control instruction There is a problem in that the accuracy of control becomes worse because a large difference occurs between the average speed used in the calculation of the value D1004 and the actual speed.

  In view of the above problems, the present invention takes time to reflect the speed control instruction value D1004 on the PWM signal SG1006 by the PWM timer 1104 even when the rotational speed of the motor is changing. Even if it is a case, it aims at performing more highly accurate control.

In order to solve the above-described problems and achieve the object, the motor control device of the present invention is a motor control device that performs rotational speed control of the motor based on a rotation output signal output by rotation of the motor , storage means for motor drive means storing time information indicating the time until is reflected in the output signal to the motor driver for driving the previous SL motor the speed control instruction value by reading the speed control instruction value, the rotation output signal A rotation speed information generating means for generating rotation speed information based on reception of the rotation speed information generating stage based on the time information at a predetermined cycle timing and the rotation output signal output before the timing. the time information and the speed control instruction value generating means but which generates the speed control instruction value based on the generated the rotation speed information, the generated speed control instruction value Read in based timing, is characterized in that it comprises said motor drive means for reflecting the read the speed control command value to the output signal to the motor driver, the.

  The motor control device further includes a control cycle signal generation device that generates a control cycle signal at a cycle based on the time information, and the speed control command value generation unit is configured to receive the speed control command based on reception of the control cycle signal. A value is generated, and the motor driving means preferably reads the generated speed control instruction value based on reception of the control cycle signal. Alternatively, a control cycle signal generation unit that generates a control cycle signal at a predetermined cycle, and a load timing signal generation unit that converts the control cycle signal into a load timing signal based on the time information and outputs the load timing signal. The speed control instruction value generating means may generate the speed control instruction value based on reception of the control cycle signal, and the driving means may read the speed control instruction value based on reception of the load timing signal.

  Furthermore, when providing an image forming apparatus provided with the motor control device of the present invention, a designation unit that designates a plurality of modes with different loads applied to the image forming apparatus, and a mode designated by the designation unit. And time information setting means for setting the time information. The plurality of modes may include a monochrome mode and a color mode.

  According to the present invention, the time information indicating the time until the motor drive means reads the speed control instruction value and actually reflects the speed instruction value on the rotation speed of the motor, which is stored in the storage means by the motor drive means. By reading the speed control instruction value based on the Based on this, the motor drive means predicts and calculates the rotation speed of the motor when the speed control instruction value is reflected in the rotation speed of the motor, and calculates the speed control instruction value using the calculated predicted speed. Therefore, it is possible to control the rotation speed of the motor with high accuracy.

  Exemplary embodiments of a motor control device and an image forming apparatus according to the present invention will be explained below in detail with reference to the accompanying drawings.

[First Embodiment]
A first embodiment of the present invention will be described with reference to FIGS. An image forming apparatus such as a copying machine, a facsimile machine, a printer machine, a scanner machine, or a digital multifunction machine called MFP (Multi Function Peripheral) that combines at least two of these functions will be described as an embodiment. .

  FIG. 1 is a hardware configuration diagram illustrating an example of an image forming apparatus according to the first embodiment of the present invention. An image forming apparatus 500 shown in FIG. 1 includes an automatic document feeder (ADF) 1, a scanner unit 2, an image writing unit 3, a developing unit 4, a photosensitive unit 5, a paper feeding unit 6, a primary transfer unit 7, and a secondary transfer. Each unit includes a roller 8, a conveyance belt 9, and a fixing unit 10.

  An automatic document feeder (ADF) 1 is a device that sequentially sends documents to the scanner unit 2. The scanner unit 2 is an apparatus that reads an image of a document by reading reflected light from the document while irradiating the document with light. The image data read by the scanner unit 2 is subjected to image processing and then sent to the image writing unit 3 as image data. The image writing unit is a unit that drives an LD (Laser Diode: laser diode) according to image data to form a latent image on the photosensitive drum in the photosensitive unit. The photoconductor unit includes four photoconductor drums of Y (Yellow: yellow), M (Magenta), C (Cyan: cyan), and Bk (Black: black) in the case of full color. The developing unit is a unit that visualizes the latent image formed on the photosensitive drum by attaching toner to the latent image.

  The toner image visualized on the photosensitive drum is transferred onto the intermediate transfer belt of the primary transfer unit 7. In the case of full color, four color toner images are sequentially superimposed. When the image formation and transfer processes for four colors are completed, the transfer paper is fed from the paper feed unit 6 in time with the primary transfer belt, and between the primary transfer unit 7 and the secondary transfer roller 8, The toner images are transferred from the transfer belt to the transfer paper simultaneously for the four colors. The conveyance belt 9 is a belt that conveys the transfer paper on which the toner image is transferred, and the fixing unit 10 is a unit that thermally fixes the toner image on the transfer paper sent by the conveyance unit belt 9.

  FIG. 2 is a hardware configuration diagram showing the configuration of the primary transfer unit 7 of FIG. 1 and the peripheral configuration for driving it. The motor 21 is a motor that is controlled by the motor control device 22 and generates the driving force of the primary transfer unit 7. The rotation of the motor 21 is transmitted to the primary transfer driving roller 24 via the gear 23. The intermediate transfer belt 25 rotates as the primary transfer driving roller 24 rotates, and transfers the toner image to the transfer paper with the secondary transfer roller 26 (that is, the secondary transfer roller 8). The encoder 27 is a device that generates a pulse waveform corresponding to the rotation speed of the motor 21 and outputs the pulse waveform as a rotation output signal SG1. The rotation speed control of the motor 21 is performed by feeding back the rotation output signal SG1.

  FIG. 3 is a block diagram showing the configuration of the motor control device 22 that controls the rotational speed of the motor 21 of FIG. A motor control device 22 that controls the speed of the motor 21 shown in FIG. 1 includes an input capture 101, a control unit 102, a register 103, a PWM timer 104, a motor driver 105, a free-run timer 107, a control cycle timer 108, and a flash memory 109. Is provided so that feedback control of the rotational speed of the motor 21 can be performed. The motor 21 is, for example, a direct current brushless motor.

  The free-run timer 107 is a timer that updates the timer value D1 with a clock signal SG3 having a frequency sufficiently higher than the rotation output signal SG1. The input capture 101 holds the timer value D1 of the free-run timer 107 as the capture value D2 at the timing when the rising edge of the rotation output signal SG1 is received. Each time the timer value D1 is held, the input capture interrupt signal SG2 is output to the control unit 102.

  The control cycle timer 108 is a timer that outputs a control cycle signal SG5 to the control unit 102. The flash memory 109 is a storage unit that holds time information D3 representing the cycle of the control cycle signal SG5.

  The control unit 102 includes a CPU 110 that is an arithmetic device, and a memory 111 such as a RAM 112 and a ROM 113 that store various types of information. When the control unit 102 receives the input capture interrupt signal SG 2, it reads the capture value D 2 held in the input capture 101, and the read capture value D 2 and the previous rotation stored in the RAM 112. Based on the capture value D2 ′ held by the reception of the rising edge of the output signal SG1, the average rotational speed V1 of the motor 21 until the current input capture interrupt signal SG2 is received is stored and stored in the RAM 112. The RAM 112 stores at least the average rotation speed V1 and the average rotation speed V1 ′ of the motor 21 calculated by the control unit 102 in the same manner when receiving the input capture interrupt signal SG2 one time before the input capture interrupt signal SG2. The average rotation speed value for two times is held. The RAM 112 holds at least the capture value D2 for one input capture interrupt signal SG2. Since the input capture interrupt signal SG2 is output every time the input capture 101 receives the rising edge of the rotation output signal SG1, the calculation of the average rotation speed of the motor 21 by the control unit 102 is performed on the rising edge of the rotation output signal SG1. It is performed at every timing.

  The control unit 102 also has a function of starting the calculation of the speed control instruction value D4 to the motor driver 105 when receiving the control cycle signal SG5. When the control unit 102 receives the control cycle signal SG5, the control unit 102 reads the timer value D1 of the free-run timer 107 at that time, and reads the read timer value D1 and 2 of the input capture interrupt signal SG2 stored in the RAM. A predicted speed V3 of the motor 21 is calculated based on the average rotational speeds V1 and V1 ′ of the motor 21 and the time information D3 stored in the flash memory 109, and between the calculated predicted speed V3 and the target speed. Is used to calculate a speed control instruction value D4 of the motor driver 105, that is, an instruction value of the rotation speed of the motor 21, by known feedback control.

  The register 103 temporarily stores the speed control instruction value D4 output from the control unit 102. In this embodiment, the register 103 is shown outside the control unit 102, but may be inside the control unit 102. The PWM timer 104 has a register 106 therein and outputs a PWM signal SG6 to the motor driver 105 based on the speed control instruction value D4 stored in the register 106. The PWM timer 104 also has a function of reading the speed control instruction value D4 from the register 103 and storing it in the internal register 106 when receiving the control cycle signal SG5. Note that the speed control instruction value D4 read from the register 103 is reflected in the generation of the PWM signal SG6 and the output to the motor driver 105 in a negligibly short time and reflected in the actual rotational speed of the motor 21. Therefore, when the PWM timer 104 reads the speed control instruction value D4 from the register 103 and reflects it in the PWM signal SG6 that is an output signal to the motor driver 105, the speed control instruction value D4 is actually reflected in the rotational speed of the motor 21. Can be considered to coincide with Therefore, the time information can be considered as information indicating the time until the PWM timer 104 reads the speed control instruction value D4 from the register 103 and actually reflects the speed control instruction value D4 on the rotation speed of the motor 21.

  The motor driver 105 has two upper and lower transistors (not shown) for each phase of the motor 21, and these transistors are repeatedly turned on and off in accordance with the PWM signal SG6 generated by the PWM timer 104. This is a device for supplying a drive voltage to the motor 21. The motor 21 is driven and rotated by this drive voltage.

  Next, the output timing of each signal will be described. Here, FIG. 4 is a timing chart showing an example of the output of each signal.

  The clock signal SG3 is a clock signal having a sufficiently higher frequency than the rotation output signal SG1 and counting up the free-run timer 107. The input capture 101 holds the timer value D1 of the free-run timer 107 at the timing (for example, time t3 in FIG. 4) when the rising edge of the rotation output signal SG1 generated by the rotation of the motor 21 is detected. The embedded signal SG2 is transmitted to the control unit 102. The control unit 102 reads the capture value D2 from the input capture 101 at the timing when the input capture interrupt signal SG2 is received. The control unit 102 captures the capture value D2 read from the input capture 101 at the timing of the current input capture interrupt signal SG2 (for example, time t3) and the timing of the rising edge of the previous rotation output signal SG1 (for example, time t1). The period T1 of the rotation output signal SG1 (for example, the time T1 ′ between times t1 and t3 in FIG. 4) is calculated by comparing with the capture value D2 ′ read out and held in the RAM 112. Further, the control unit 102 uses the calculated period T1 as the physical distance of the principle of outputting the rotation output signal SG1 (for example, when a rotary encoder is used as the encoder 27, the slit of the slit plate provided on the rotation shaft of the motor 21). The average rotation speed V1 of the motor 21 in one cycle immediately before the rising edge of the rotation output signal SG1 corresponding to the calculated cycle T1 of the rotation output signal SG1 is calculated. The control unit 102 stores the calculated average rotation speed V1 and the capture value D2 read from the input capture 101 at time t3, for example, in the RAM 112.

  Further, the control unit 102 calculates the speed control instruction value D4 at the timing of receiving the control cycle signal SG5 (for example, time t5 in FIG. 4), and outputs the speed control instruction value D4 obtained by the calculation to the register 103. . Specifically, when receiving the control cycle signal SG5, the control unit 102 reads the timer value D1 of the free-run timer 107 at that time (for example, time t5). By comparing the read timer value D1 with the capture value D2 held in the RAM 112 at the reception timing (for example, time t4) of the previous rotation output signal SG1, the reception timing of the immediately previous rotation output signal SG1 ( For example, a time T2 (hereinafter referred to as “interpolation time T2”) from the time t4) to the reception timing of the control cycle signal SG5 (for example, time t5) is calculated. Further, the control unit 102 stores the average speed V1 of the motor 21 in one cycle immediately before the rotation output signal SG1 (for example, T1 from time t3 to t4) and one cycle immediately before the previous time (for example, stored in the RAM 112). The average rotational speed V1 ′ of the motor 21 at time t1 to t3 (T1 ′) is read out. The control unit 102 calculates the amount of change in the average rotational speed of the motor 21 on the time axis by comparing the average rotational speed V1 ′ and V1 of the motor 21 in each of the two adjacent cycles of the rotational output signal SG1. Next, the control unit 102 calculates the calculated change amount of the average rotation speed of the motor 21, the average rotation speeds V 1 ′ and V 1, the interpolation time T 2, and the time information D 3 (that is, interpolation) stored in the flash memory 109. Using the time T3), the PWM timer 104 reads the speed control instruction value D4 from the register 103 and reflects it in the PWM signal SG6 that is an output signal to the motor driver 105 (for example, time t8). Is calculated. Specifically, for example, based on FIG. 5, the predicted motor speed V3 is obtained by a known interpolation calculation. Based on the calculated predicted motor speed V3 and the target speed stored in the ROM 113, the control unit 102 calculates a speed control instruction value D4, that is, an instruction value for the rotational speed of the motor 21 by known feedback control. The obtained speed control instruction value D4 is output to the register 103. The time taken from when the control unit 102 receives the control cycle signal SG5 (for example, time t5) until the speed control instruction value D4 is calculated and output to the register 103 is determined by other processes performed by the control unit 102. Although depending on the situation, it is within the cycle of the control cycle signal SG5.

  The PWM timer 104 reads the speed control instruction value D4 from the register 103 at the reception timing (for example, time t8) of the control cycle signal SG5 and stores the speed control instruction value D4 in the register 106. The speed control instruction value D4 read at this time (for example, time t8) is the speed control instruction value calculated by the control unit 102 at the reception timing (for example, time t5) of the control period signal SG5 output by the control period timer 108 one time before. D4. The PWM timer 104 generates a PWM signal SG6 based on the speed control instruction value D4 stored in the register 106 and outputs it to the motor driver 105. For example, after the speed control instruction value D4 is read from the register 103 and stored in the register 106 of the PWM timer 104 at time t8, the PWM signal SG6 is generated based on the stored speed control instruction value D4. When the PWM timer 104 generates the PWM signal SG6 and outputs it to the motor driver 105, the motor driver 105 is driven, and the rotational speed of the motor 21 is controlled to be the rotational speed corresponding to the speed control instruction value D4. The

  That is, the PWM signal SG6 after time t5 indicated by A in FIG. 4 is obtained before and after the capture value D2 read from the input capture 101 by the control unit 102 by the input capture interrupt signal SG2 immediately after time t1 indicated by a. This is generated by calculating the speed control instruction value D4 using the captured value. Similarly, the PWM signal SG6 after time t8 indicated by B is the capture value D2 read from the input capture 101 by the control unit 102 by the input capture interrupt signal SG2 immediately after time t4 indicated by b and the capture value obtained before that. Is generated by calculating the speed control instruction value D4 using.

  FIG. 5 schematically shows the relationship between the cycles T1 ′ and T1 of the rotation output signal SG1, the average rotation speeds V1 ′ and V1 of the motor 21 and the interpolation times T2 and T3. The PWM signal SG6 is used for speed control. 4 is a graph schematically showing a relationship between a time required until an instruction value D4 is reflected and a change in the rotation speed of the motor 21. In the present embodiment, when the PWM timer 104 receives the control cycle signal SG5 (at the timing of time t8 in the above example), the PWM timer 104 reads the speed control instruction value D4 from the register 103. For this reason, the interpolation time T3 in FIG. 5 is the same as the cycle of the control cycle signal SG5. The interpolation time T2 is a time from reception of the rotation output signal SG1 to reception of the control cycle signal SG5, which is calculated when the control unit 102 receives the control cycle signal SG5. That is, the interpolation time T2 + interpolation time T3 is PWM (at the timing of time t5 in the above example) after the motor control device 22 receives the rotation output signal SG1 (at the timing of time t8 in the above example). This is the time until the speed control instruction value D4 is reflected in the signal SG6.

  The control unit 102 stores the average rotation speed V1 in the cycle T1 (for example, times t3 to t4) stored in the RAM 112 and the cycle T1 ′ (for example, times t1 to t3) of the rotation output signal SG1 immediately before the cycle T1. Based on the average rotation speed V1 ′, the interpolation time T2 (for example, time t4 to t5) and the interpolation time T3 (for example, time t5 to t8), for example, at time t5, the PWM timer 104 outputs the speed control instruction value D4 to the PWM signal. The rotational speed V3 of the motor 21 at the time of reflection in SG6 (for example, time t8) is predicted. The calculation of the predicted rotation speed V3 may be performed based on three or more average rotation speeds. It is also possible to calculate the predicted rotational speed V3 with higher accuracy based on the accumulated error of the average rotational speed.

  Thus, according to the present embodiment, when the flash memory 109 holds the cycle T3 of the control cycle signal SG5 as the time information D3 and the PWM timer 104 receives the control cycle signal SG5, the speed control instruction value D4 is registered. 103 is read and reflected in the PWM signal SG6. Therefore, the control unit 102 can grasp the timing at which the PWM timer 104 reflects the speed control instruction value D4 in the PWM signal SG6 by reading the time information D3 from the flash memory 109. That is, the control unit 102 can calculate the speed control instruction value D4 using the predicted rotation speed V3 at the time when the speed control instruction value D4 is reflected in the PWM signal SG6, and can control the rotation speed of the motor 21. Therefore, the rotational speed of the motor 21 can be controlled with high accuracy.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS. In addition, the part which has the structure similar to 1st Embodiment mentioned above is shown with the same code | symbol, and abbreviate | omits description.

  In the first embodiment, the flash memory 109 holds the cycle T3 of the control cycle signal SG5 as time information D3. Therefore, by reading the time information D3 from the flash memory 109, the control unit 102 can obtain the timing at which the PWM timer 104 reads the speed control instruction value D4. Thereby, it is possible to predict the rotation speed V3 of the motor 21 when the PWM timer 104 reflects the speed control instruction value D4 in the PWM signal SG6. However, in the first embodiment, when the time T3 from when the control unit 102 receives the control cycle signal SG5 to when the PWM timer 104 reflects the speed control instruction value D4 in the PWM signal SG6 is long, it is actually When the motor speed fluctuates, there is a possibility that an error occurs between the predicted rotation speed V3 and the actual rotation speed. In the present embodiment, in order to reduce the cause of the error and perform more accurate control, after the control unit 102 receives the control cycle signal SG5, the PWM timer 104 changes the speed control instruction value D4 to the PWM signal SG6. The time until reflection is set by the longest time predicted when the control unit 102 calculates the speed control instruction value D4 (hereinafter referred to as the predicted longest calculation time). In this respect, the configuration of the first embodiment is different from that of the present embodiment.

  FIG. 6 is a block diagram showing a configuration of a motor control device 22 that controls the speed of the motor 21 according to the second embodiment of the present invention. As shown in FIG. 6, the motor control device 22 according to the present embodiment includes a load timing signal generation timer 201. The load timing signal generation timer 201 is a timer that outputs the load timing signal SG201 with a predetermined time delay when receiving the control cycle signal SG5. This predetermined time is stored in the flash memory 109 as time information D203, and is stored in the register 202 in the load timing signal generation timer 201 when the power is turned on or when the time information D203 is changed. The time information D203 represents a time obtained by adding a predetermined margin time to the predicted longest calculation time of the control unit 102. The predicted maximum calculation time is an empirically obtained time.

  FIG. 7 is a timing chart showing an example of the output timing of each signal according to the present embodiment. The calculation of the average speed V1 performed when the control unit 102 receives the input capture interrupt signal SG2 and the calculation of the interpolation time T2 performed when the control unit 102 receives the control cycle signal SG5 are the first implementation. Since it is the same as the embodiment, the description is omitted.

  For example, when the control unit 102 receives the control cycle signal SG5 at time t6 in FIG. 7, for example, the control unit 102 calculates the speed control instruction value D4 and outputs it to the register 103. Specifically, after calculating the interpolation time T2 (for example, time t5 to t6), the control unit 102 performs two consecutive cycles T1 ′ (for example, time t1 to t3) and T1 of the rotation output signal SG1 stored in the RAM 112. The average rotational speeds V1 ′ and V1 of the motor 21 at (for example, times t3 to t5) are read, and the amount of change in the rotational speed of the motor 21 on the time axis is calculated based on the average rotational speeds V1 ′ and V1. Next, the control unit 102 calculates the amount of change in the rotational speed of the motor 21, the average rotational speeds V 1 ′ and V 1, the interpolation time T 2, and the time information D 203 (that is, the interpolation) stored in the flash memory 109. Using the time T203), the PWM timer 104 calculates the predicted motor speed V203 at the time (for example, time t7) when the speed control instruction value D4 is reflected in the PWM signal SG6. Specifically, as in the first embodiment, the predicted motor speed V203 is obtained by a well-known interpolation calculation, for example, based on FIG. Here, the time information D203 is a time obtained by adding a predetermined margin time to the predicted longest calculation time of the control unit 102 as described above, and the load timing signal generation timer 201 receives the control cycle signal SG5 at time t6, for example. Then, for example, a time T203 from when the load timing signal SG201 is generated at time t7 is shown. When the control unit 102 calculates the speed control instruction value D4 by a known feedback control based on the predicted motor speed V203 and the target speed stored in the ROM 113, the control unit 102 outputs the speed control instruction value D4 to the register 103.

  When receiving the control cycle signal SG5, the load timing signal generation timer 201 outputs a load timing signal SG201 with a delay of a predetermined time T203. Specifically, when the control cycle signal SG5 is received, the load timing signal is output after the number of clocks corresponding to the time information stored in the register 202 has elapsed in the clock of the clock signal SG4.

  For example, when receiving the load timing signal SG201 at time t7, the PWM timer 104 reads the speed control instruction value D4 from the register 103 and stores it in the register 106 in the PWM timer 104. The PWM timer 104 generates a PWM signal SG6 based on the speed control instruction value D4 stored in the register 106 and outputs the PWM signal SG6 to the motor driver 105. When the PWM timer 104 generates the PWM signal SG6 and outputs it to the motor driver 105, the motor driver 105 is driven, and the rotational speed of the motor 21 can be controlled to the rotational speed according to the speed control instruction value D4.

  That is, the PWM signal SG6 after time t4 indicated by A in FIG. 7 is obtained before and after the capture value D2 read from the input capture 101 by the control unit 102 by the input capture interrupt signal SG2 immediately after time t1 indicated by a. This is generated by calculating the speed control instruction value D4 using the captured value. Similarly, the PWM signal SG6 after time t7 indicated by B is the capture value D2 read from the input capture 101 by the control unit 102 by the input capture interrupt signal SG2 immediately after time t5 indicated by b and the capture value obtained before that. Is generated by calculating the speed control instruction value D4 using. Similarly, the PWM signal SG6 after time t10 indicated by C is the capture value D2 read from the input capture 101 by the control unit 102 by the input capture interrupt signal SG2 immediately after time t8 indicated by c and the capture value obtained before that. Is generated by calculating the speed control instruction value D4 using.

  FIG. 8 schematically shows the relationship between the cycles T1 ′ and T1 of the rotation output signal SG1 and the average rotation speeds V1 ′ and V1 of the motor 21 and the interpolation times T2 and T203. A speed control instruction is given to the PWM signal SG6. 4 is a graph schematically showing a relationship between a time required until a value D4 is reflected and a change in rotational speed of the motor 21. In the present embodiment, for example, when the PWM timer 104 receives the load timing signal SG201 at time t7, the PWM timer 104 reads the speed control instruction value D4 from the register 103. Therefore, the interpolation time T203 in FIG. 8 is the same as the time T203 from when the load timing signal generation timer 201 receives the control cycle signal SG5 to when the load timing signal SG201 is output. Further, the interpolation time T2 is calculated when the control unit 102 receives the control cycle signal SG5, from the reception of the rising edge of the rotation output signal SG1 (for example, time t5) to the reception of the control cycle signal SG5 (for example, time t6). Is the time. That is, for the interpolation time T2 + interpolation time T203, until the motor control device 22 receives the rising edge of the rotation output signal SG1 (for example, time t5), the speed control instruction value D4 is reflected in the PWM signal SG6 (for example, time t7). It will be time.

  The control unit 102 sets the average speed of the cycle T1 (for example, times t3 to t5) stored in the RAM 112 to V1, and the cycle T1 ′ of the rotation output signal SG1 immediately before the cycle T1 (for example, times t1 to t3). Based on the speed V1 ′, the interpolation time T2 (for example, time t5 to t6) and the interpolation time T203 (for example, time t6 to t7), The rotational speed V203 of the motor 21 at time t7) is predicted.

  As described above, according to the present embodiment, the time T203 from when the control unit 102 receives the control cycle signal SG5 to when the PWM timer 104 reflects the speed control instruction value D4 in the PWM signal SG6 is represented by the time information D203. Is stored in the flash memory 109. The control unit 102 reads the time information D203 stored in the flash memory 109, thereby predicting the rotational speed of the motor 21 at the time (for example, t7) when the speed control instruction value D4 is reflected in the PWM signal SG6. Based on the predicted rotation speed of the motor 21, the speed control instruction value D4 can be calculated. The time information D203 is determined as a time shorter than the cycle of the control cycle signal SG5 (interpolation time T3 in the first embodiment) according to the predicted longest calculation time of the control unit 102. As a result, the amount of change in the rotational speed of the motor 21 from when the control unit 102 starts computation (for example, time t6) until the PWM timer 104 reflects the speed control instruction value D4 in the PWM signal SG6 (for example, time t7). It is possible to suppress an error in the predicted speed V203 due to fluctuations in. Thereby, the speed of the motor 21 can be controlled with high accuracy.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIGS. In addition, the part which has the structure similar to 1st Embodiment mentioned above is shown with the same code | symbol, and abbreviate | omits description.

  In the second embodiment, a time T203 from when the control unit 102 receives the control cycle signal SG5 to when the PWM timer 104 reflects the speed control instruction value D4 in the PWM signal SG6 is set based on the predicted longest calculation time. By doing so, the error factor of the predicted speed V203 is reduced. However, the time required for the control unit 102 to actually calculate the speed control instruction value D4 varies depending on the load on the CPU 110. For this reason, when the predicted longest calculation time is set in accordance with a heavy load on the CPU 110, the PWM timer 104 reflects the speed control instruction value in the PWM signal SG6 after the control unit 102 receives the control cycle signal SG5 as a result. It takes a relatively long time to make it happen. As a result, even when the load on the CPU 110 is light, there is a possibility of having the same error factor as when the load on the CPU 110 is heavy.

  In the present embodiment, the time from when the control unit 102 receives the control cycle signal SG5 until the PWM timer 104 reflects the speed control instruction value D4 in the PWM signal SG6 can be changed according to the load state of the CPU 110. To. The load on the CPU 110 varies depending on the operating conditions of the image forming apparatus. Among the modes such as a copy mode and a facsimile mode that the image forming apparatus has, the load on the CPU 110 varies depending on the monochrome mode and the color mode in the copy mode. In the present embodiment, as an example, the PWM timer 104 reflects the speed control instruction value D4 in the PWM signal SG6 in accordance with the load variation of the CPU 110 between the monochrome mode and the color mode in the copy mode. It is possible to change the time until Note that this change in time may be performed in accordance with a change in the load on the CPU 110 due to other factors. For example, the processing may be performed in accordance with a change in the load on the CPU 110 between the copy mode and the facsimile mode.

  FIG. 9 is a block diagram showing the configuration of the motor control device 22 that controls the speed of the motor 21. The flash memory 109 according to the present embodiment stores predetermined time information D304 together with time information D203 set based on the predicted longest calculation time. The control unit 102 has a function of changing the time information D203 read from the flash memory 109 based on the load of the CPU 110 and outputting the time information D303.

  As shown in FIG. 9, in the case of the third embodiment, an external device provided in the motor control device 22 from the system control unit 50 as an instruction means included in the image forming apparatus 500 having the motor control device 22. Information indicating whether the current image forming mode is the color mode or the monochrome mode is provided to the CPU 110 of the control unit 102 via the communication unit 120 having a communication function with the control unit 102. The CPU 110 holds the same information in the RAM 112. The system control unit 50 includes a mode determination unit 51 that determines whether the current image forming mode is a color mode or a monochrome mode. The system control unit 50 is constituted by a computer, for example, and the mode determination unit 51 can be realized in the form of a program executed by the computer. The system control unit 50 has a function of controlling the operation of the entire image forming apparatus 500, and is connected to the operation unit 60 and the scanner 70 (that is, the scanner unit 2 in FIG. 1) of the image forming apparatus 500. When the user performs an operation for designating the color mode or the monochrome mode on the operation unit 60 of the image forming apparatus 500, the mode determination unit 51 determines whether the current image formation mode is the color mode or the monochrome mode according to the operation. Determine. When a document image is read from the scanner 70 included in the image forming apparatus 500, the mode determination unit 51 determines whether the image data is a color image or a monochrome image from the RGB values of the read image data. . Specifically, the mode discriminating unit 51 discriminates that the image data is a monochrome image if the image data is data representing only the density between black and white, and otherwise determines that it is a color image. Determine. The mode discriminating unit 51 automatically discriminates whether the current image forming mode is the color mode or the monochrome mode according to the discrimination result.

  FIG. 10 is a flowchart showing a process in which the control unit 102 changes the time information D203 to the time information D303 based on the load of the CPU 110 and outputs it. This processing is performed when the image forming apparatus is turned on, or when the monochrome and color modes are changed. First, the control unit 102 reads time information D203 from the flash memory 109 (ST1). Next, it is determined whether or not the current mode is color (ST2). As described above, the control unit 102 holds information about whether the current image forming mode is color or monochrome in the RAM 112. When the color mode is determined in ST2, the time information D203 read from the flash memory 109 is output as it is to the register 202 in the load timing signal generation timer 201 as the time information D303 (ST3).

  If it is determined in ST2 that the color mode is not selected, the time indicated by the time information D303 is shortened by a predetermined value because the CPU 110 is in a monochrome mode with a light load. This predetermined value is stored in the flash memory 109 as time information D304. The control unit 102 reads the time information D304 from the flash memory 109 (ST4). In the next step, time information D304 is subtracted from time information D203 (ST5). The subtraction result is output as D303 to the register 202 in the load timing signal generation timer 201 (ST6). Then, control unit 102 stores the value of time information D303 in RAM 112 for use in calculation of speed control instruction value D4 (ST7).

  In the present embodiment, the time information D203 is set to the predicted longest calculation time, and in the monochrome mode with a light load on the CPU 110, the time information D303 is subtracted from the time information D203 to shorten the time information D303 by a predetermined time. However, D203 may be set as the predicted shortest calculation time, and in the color mode with a heavy load on the CPU 110, the time information D304 may be added to make the time information D303 longer by a predetermined time. Further, the time information D203 may be set as the predicted longest calculation time, the time information D304 may be set as the minimum predicted calculation time, and the time information to be read as the time information D303 may be switched depending on the monochrome mode or the color mode.

  FIG. 11 is a timing chart showing an example of the output timing of each signal according to the present embodiment. The calculation of the average rotational speed V1 of the motor 21 performed by the control unit 102 receiving the input capture interrupt signal SG2 and the calculation of the interpolation time T2 performed by the control unit 102 receiving the control cycle signal SG5 are as follows: Since it is the same as that of the first embodiment, the description is omitted.

  For example, when the control unit 102 receives the control cycle signal SG5 at time t6 in FIG. 11, for example, the control unit 102 calculates the speed control instruction value D4 and outputs it to the register 103. Specifically, after calculating the interpolation time T2 (for example, time t5 to t6), the control unit 102 performs two consecutive cycles T1 ′ (for example, time t1 to t3), T1 of the rotation output signal SG1 stored in the RAM 112. The average rotational speeds V1 ′ and V1 of the motor 21 at each time (for example, times t3 to t5) are read, and the amount of change in the rotational speed of the motor 21 on the time axis is calculated. Next, the control unit 102 calculates the amount of change in the rotational speed of the motor 21, the average rotational speed V1 ′, V1, the interpolation time T2, and the time information D303 stored in the RAM 112 (that is, the interpolation time T304 or T303) is used to calculate the predicted motor speed V304 or V303 at the time (for example, time t7) when the PWM timer 104 reads the speed control instruction value D4 and reflects it on the PWM signal SG6. Specifically, for example, based on FIG. 12, the predicted motor speed V304 or V303 is obtained by a known interpolation calculation. As described above, since the value of the time information D303 is different between the monochrome mode and the color mode, the predicted motor speed is different between the monochrome mode and the color mode.

  When receiving the control cycle signal SG5, the load timing signal generation timer 201 outputs the load timing signal SG201 based on the time information D303 stored in the register 202. When receiving the load timing signal SG201, the PWM timer 104 reads the speed control instruction value D4 from the register 103 and outputs the PWM signal S6 to the motor driver. Since the value of the time information D303 is different between the monochrome mode and the color mode, the PWM timer 104 sends the speed control instruction value D4 to the PWM signal SG6 after the control unit 102 receives the control cycle signal SG5 in the monochrome mode and the color mode. The time until reflection (for example, times t6 to t7) varies. In FIG. 11, T303 is the time indicated by D303 in the monochrome mode, and T304 is the time indicated by D303 in the color mode.

  That is, the PWM signal SG6 after time t4 indicated by A in FIG. 11 is obtained before and after the capture value D2 read from the input capture 101 by the control unit 102 with the input capture interrupt signal SG2 immediately after time t1 indicated by a. This is generated by calculating the speed control instruction value D4 using the captured value. Similarly, the PWM signal SG6 after time t7 indicated by B is the capture value D2 read from the input capture 101 by the control unit 102 by the input capture interrupt signal SG2 immediately after time t5 indicated by b and the capture value obtained before that. Is generated by calculating the speed control instruction value D4 using. Similarly, the PWM signal SG6 after time t11 indicated by C is the capture value D2 read from the input capture 101 by the control unit 102 with the input capture interrupt signal SG2 immediately after time t9 indicated by c, and the capture value obtained before that. Is generated by calculating the speed control instruction value D4 using.

  Further, in FIG. 11, the period of the PWM signal SG6 varies during the mode conversion from color to monochrome (in the figure, for example, between times t4 and t5). However, generally, image formation is not performed immediately after such mode conversion, and therefore, the formed image is not affected by fluctuations in the period of the PWM signal SG6.

  FIG. 12 schematically shows the relationship between the cycles T1 ′ and T1 of the rotation output signal SG1, the average rotation speed V1 ′ and V1 of the motor 21, the interpolation time T2, and the interpolation time T304 or T303. 7 is a graph schematically showing the relationship between the time required until the speed control instruction value D4 is reflected in SG6 and the change in the rotational speed of the motor 21. In the present embodiment, when receiving the load timing signal SG201, the PWM timer 104 reads the speed control instruction value D4 from the register 103, stores it in the register 106 in the PWM timer 104, and stores the speed control instruction stored in the register 106. The PWM signal SG6 is generated using the value D4. When receiving the control cycle signal SG5, the load timing signal generation timer 201 outputs the load timing signal SG201 based on the time information D303 stored in the register 202. That is, the time T303 or T304 from when the control unit 102 receives the control cycle signal SG5 until the PWM timer 104 reflects the speed control instruction value D4 in the PWM signal SG6 is represented by the time information D303 stored in the RAM 112. Same as time. The time information D303 is a value changed by the control unit 102 based on the load on the CPU 110.

  When the image forming mode is color, the load on the CPU 110 is large, so the value indicated by the time information D303 is T304. Further, when the image forming mode is monochrome, the load on the CPU 110 is small, so the value indicated by the time information D303 is T303, which is shorter. The interpolation time T2 is a time from the reception of the rotation output signal SG1 to the reception of the control cycle signal SG5 calculated when the control unit 102 receives the control cycle signal SG5 (for example, time t5 to t6 in FIG. 11, for example). It is. Complement time T2 + complement time T303 or T304 is a time from when the motor control device 22 receives the rotation output signal SG1 until the speed control instruction value D4 is reflected in the PWM signal SG6 (for example, time t5 to t7).

  The control unit 102 sets the average rotation speed of the motor in the cycle T1 (for example, times t3 to t5) stored in the RAM 112 to V1, and the cycle T1 ′ of the rotation output signal SG1 immediately before T1 (for example, times t1 to t3). ) And the time when the PWM timer 104 reflects the speed control instruction value D4 in the PWM signal SG6 (for example, based on the interpolation time T2 and the interpolation time T303 or T304 (for example, time t5 to t7)) The speed V303 or V304 at time t7) is predicted.

  Thus, according to the present embodiment, the time information D303 from when the control unit 102 receives the control cycle signal SG5 to when the PWM timer 104 reflects the speed control instruction value D4 in the PWM signal SG6 is stored in the register 202. And stored in the RAM 112. The time information D303 is calculated from the predicted longest calculation time D203 stored in the flash memory 109 and the variation time information D304 of the time information D203, and when the load on the CPU 110 is heavy, the predicted longest calculation time D203 is directly used as the time information. When the load is small, a value obtained by subtracting the variation time information D304 from D203 is output as time information D303. Thereby, the time from when the control unit 102 receives the control cycle signal SG5 to when the PWM timer 104 reflects the speed control instruction value D4 in the PWM signal SG6 can be changed by the load of the CPU 110. That is, when the calculation time of the CPU 110 is short, the time from when the control unit 102 receives the control cycle signal SG5 to when the PWM timer 104 reflects the speed control instruction value D4 in the PWM signal SG6 can be shortened. Therefore, it is possible to suppress an error in the predicted speed due to the change in the speed change amount during that time. Thereby, the speed of the motor 21 can be controlled with high accuracy.

  In each of the above embodiments, a toner image is once transferred from the photosensitive unit onto an intermediate medium (intermediate transfer belt) and superimposed on the intermediate medium to form a color image. Although the application example to the color image forming apparatus of the “indirect transfer method” in which the transfer unit performs transfer to the transfer paper at a time has been described, the present invention is not limited to this, and a single color toner image formed on each image carrier The present invention can be similarly applied to a “direct transfer type” color image forming apparatus that sequentially transfers the image onto a transfer sheet, which is a transfer body conveyed by an intermediate medium (conveyance belt).

  In each of the above embodiments, the example in which the motor control device is used in the image forming apparatus has been described. However, the present invention is not limited to this, and the rotation speed of the motor is based on the rotation output signal output by the rotation of the motor. Any device other than the image forming apparatus may be used as long as it performs control. Other application examples of the present invention include, for example, application to an electric power steering of an automobile.

  In each of the above embodiments, the PWM timer 104 converts the speed control instruction value D4 into the PWM signal SG6 and transmits it to the motor driver 105 to control the speed of the motor 21. However, the present invention is limited to this configuration. There is no need. For example, a D / A converter is provided in place of the PWM timer 104, and the speed control instruction value D4 as a digital signal is converted by the D / A converter into an analog signal having a corresponding DC (that is, direct current) level. The speed of the motor 21 may be controlled.

1 is a hardware configuration diagram illustrating an example of an image forming apparatus according to a first embodiment of the present invention. FIG. 3 is a hardware configuration diagram illustrating a primary transfer unit and a peripheral configuration for driving the primary transfer unit. It is a block diagram which shows the structure of a motor control apparatus. It is a timing chart which shows an example of the output timing of each signal. 6 is a graph schematically showing a relationship between a time required for reflecting a speed control instruction value to a PWM signal and a speed change. It is a block diagram which shows the structure of the motor control apparatus concerning the 2nd Embodiment of this invention. It is a timing chart which shows an example of the output timing of each signal. 6 is a graph schematically showing a relationship between a time required for reflecting a speed control instruction value to a PWM signal and a speed change. It is a block diagram which shows the structure of the motor control apparatus concerning the 3rd Embodiment of this invention. It is a flowchart showing the process which a control part changes and outputs time information based on the load of CPU. It is a timing chart which shows an example of the output timing of each signal. 6 is a graph schematically showing a relationship between a time required for reflecting a speed control instruction value to a PWM signal and a speed change. It is a block diagram showing the structure of the conventional motor control apparatus. It is a graph which shows an example of the conventional speed change.

Explanation of symbols

1 Automatic document feeder (ADF)
DESCRIPTION OF SYMBOLS 2 Scanner unit 3 Image writing unit 4 Developing unit 5 Photoconductor unit 6 Paper feeding part 7 Primary transfer unit 8 Secondary transfer roller 9 Conveying belt 10 Fixing unit 21 Motor 22 Motor control device 23 Gear 24 Primary transfer drive roller 25 Intermediate transfer belt 26 Secondary transfer roller 27 Encoder 28 Scale sensor 101 Input capture (an example of rotational speed information generating means)
102 Control unit (an example of speed control instruction value generation means)
103 register 104 PWM timer (an example of PWM signal generation means)
105 Motor driver (an example of motor driving means)
106 registers (within PWM timer)
107 free run timer 108 control cycle timer (an example of control cycle signal generation means)
109 Flash memory (an example of storage means)
110 CPU
111 memory 112 RAM
113 ROM
201 Load timing signal generation timer (an example of load timing generation means)
202 register (in load timing signal generation timer)
500 Image forming device SG1 Rotation output signal SG2 Input capture interrupt signal SG3 Clock signal SG4 Clock signal SG5 Control cycle signal SG6 PWM signal SG201 Load timing signal D1 Timer value D2 Capture value (an example of rotation speed information)
D3 Time information (SG5 cycle information)
D4 Speed control command value D203 Time information (estimated longest calculation time + predetermined margin time)
D303 Time information (delay time of load timing signal generation timer: after control unit processing)
T1 period (period of rotation output signal)
T2 interpolation time T3 interpolation time (cycle of SG5)
T203 Interpolation time (delay time of load timing signal generation timer)
T303 Interpolation time (delay time of load timing signal generation timer: monochrome mode)
T304 Interpolation time (delay time of load timing signal generation timer: color mode)
V1 average speed V3 predicted speed V203 predicted speed V303 predicted speed (monochrome mode)
V304 Prediction speed (color mode)
1021 Motor 1105 Motor driver 1026 Encoder 1101 Input capture (HSI unit)
1104 PWM timer (pulse width modulation unit)
1107 Free-run timer (timer)
1110 CPU
1111 Memory (FIFO)
SG1001 Rotation output signal (encoder pulse)
SG1002 Input capture interrupt signal (interrupt)
SG1003 Clock signal (microcontroller clock)
SG1006 PWM signal (control signal)
D1001 Timer value (occurrence time)
D1002 Capture value (time)
D1004 Speed control instruction value (encoder feedback information)

Claims (7)

A motor control device that controls the rotation speed of the motor based on a rotation output signal output by rotation of the motor,
Storage means for motor drive means storing time information indicating the time until is reflected in the output signal to the motor driver for driving the previous SL motor the speed control instruction value by reading the speed control instruction value,
Rotation speed information generating means for generating rotation speed information based on reception of the rotation output signal;
The speed control instruction value is generated based on the time information and the rotation speed information generated by the rotation speed information generation unit based on the rotation output signal output before the timing at a predetermined cycle timing. Speed control instruction value generating means for performing,
The motor driving means for reading the generated speed control instruction value at a timing based on the time information, and reflecting the read speed control instruction value in an output signal to the motor driver ;
A motor control device comprising: The time information indicates a cycle of a control cycle signal that triggers the speed control command value generation unit to start generating the speed control command value,
The motor control device according to claim 1, wherein the motor driving unit reads the generated speed control instruction value based on reception of the control cycle signal. A control period signal generating means for generating a control period signal at a predetermined cycle,
Load timing signal generating means for converting the control cycle signal into a load timing signal based on the time information and outputting the load timing signal;
Further comprising
The speed control instruction value generating means generates the speed control instruction value based on reception of the control cycle signal,
The motor control device according to claim 1, wherein the motor driving unit reads the speed control instruction value based on reception of the load timing signal. An image forming apparatus comprising a transfer means for transferring transfer paper or a toner image during image formation,
An image forming apparatus comprising: a motor control device according to claim 1 that controls a motor that drives the conveying unit. Conveying means for conveying transfer paper or toner image during image formation,
The motor control device according to claim 1 or 3 controls a motor that drives the conveying means,
The image forming apparatus includes a plurality of modes with different loads on the motor control device, and performs image forming processing in a designated mode,
Instruction means for instructing the mode;
Time information setting means for setting the time information based on a mode instructed by the instruction means;
An image forming apparatus comprising: The plurality of modes include a monochrome mode and a color mode,
6. The image forming apparatus according to claim 5, wherein the time indicated by the time information is shorter in the monochrome mode than in the color mode. A motor control method for controlling the rotation speed of the motor based on a rotation output signal output by rotation of the motor,
Generating rotation speed information based on the rotation output signal output by rotation of the motor;
The rotation speed information generated in the step of generating the rotation speed information based on the rotation output signal output before the timing at a predetermined cycle timing, and a motor stored in a predetermined storage means It said velocity control instruction value based on the write-the speed control instruction value read speed control instruction value to the time information indicating the time until it is reflected in the output signal to the motor driver for driving the motor in the drive step Generating step;
Read at a timing based on the generated speed control instruction value before Symbol time between information, a step of reflecting the read the speed control command value to the output signal to the motor driver,
A motor control method comprising:

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