JP4600804B2 - Motor control apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a motor control device that controls rotation of a motor and an image forming apparatus having the motor control device.

  2. Description of the Related Art As a motor control device, a device that controls the rotational speed of a motor by detecting the rotational speed of the motor and feeding back a difference from the target rotational speed is known (see Patent Document 1).

JP-A-10-327594

  However, when the motor is downsized, the data indicating the motor rotation speed becomes coarse, or the data accuracy becomes low, and it may be difficult to control the motor rotation speed.

  SUMMARY An advantage of some aspects of the invention is that it provides a motor control device that can accurately control the rotation speed of a motor even if the motor is downsized, and an image forming apparatus having the motor control device.

According to a first aspect of the present invention, a motor, a rotation detector that generates a pulse according to the rotation of the motor and detects the rotation of the motor, and a plurality of pulses generated by the rotation detector are provided. and averaging means the width and the rotation detector respectively averaging a plurality of pulses of the pulse interval generated, based on a pulse having a pulse width and pulse interval the averaging means is averaged at least 2 about the motor A counting means for counting the number of rotation speed data, a difference calculation means for calculating a difference in rotation speed with respect to the target rotation speed of the motor based on each of at least two kinds of rotation speed data counted by the counting means, and A modulation pulse generating means for generating a pulse having a pulse width modulated based on the difference in rotation speed calculated by the difference calculating means; and Based on the form of pulses, in a motor control device and a driving means for driving the motor. That is, the number of rotations of the motor is controlled based on the rotation number data of the motor counted by averaging the pulse widths of the plurality of pulses generated by the rotation detector and the pulse intervals of the plurality of pulses generated by the rotation detector. Therefore, even if the motor is downsized and the pulses generated by the rotation detector vary, the rotational speed of the motor can be accurately controlled.

Preferably, the averaging means, the rotation detector that is turn into successively average at least one pulse interval of a plurality of pulses the pulse widths of the plurality of pulses and the rotation detector is generated to occur. That is, the rotation of the motor is determined based on the motor rotation number data obtained by sequentially averaging at least one of the pulse widths of the plurality of pulses generated by the rotation detector and the pulse intervals of the plurality of pulses generated by the rotation detector. Since the number can be controlled, the number of rotations of the motor can be accurately controlled even when the motor is downsized and the accuracy of the pulses generated by the rotation detector is low.

  Preferably, the difference calculation means calculates a difference in the number of revolutions composed of a binary value including a value indicating a difference of 0 or more and a value indicating a difference of 0 or less. Therefore, since the processing based on the difference in the rotational speed with respect to the target rotational speed of the motor can be performed with a simple configuration, the delay until the modulation pulse generating means generates the pulse can be shortened, and the rotational speed of the motor can be reduced. It can be controlled with high accuracy.

  Preferably, the apparatus further includes timing adjusting means for adjusting at least one of a rising timing and a falling timing of a pulse generated by the modulation pulse generating means when the motor is started. Therefore, overshoot can be reduced and step-out can be prevented according to the state of the motor.

  Preferably, the timing adjustment means is at least one of a rise timing and a fall timing of a pulse generated by the modulation pulse generation means according to at least one of a load, a size and a target rotation speed of the motor. Adjust. Therefore, overshoot can be reduced and step-out can be prevented according to the load, size and target rotational speed of the motor.

  Preferably, the apparatus further includes frequency changing means for changing the frequency of the pulse generated by the modulation pulse generating means. Preferably, the frequency changing means changes the frequency of the pulse generated by the modulation pulse generating means in accordance with at least one of the load, size and target rotational speed of the motor. Therefore, overshoot can be reduced and step-out can be prevented according to the load, size and target rotational speed of the motor.

  Preferably, the target rotation speed changing means for changing the target rotation speed of the motor, and the modulation pulse generating means when the target rotation speed is changed while the motor is rotating by the target rotation speed changing means. And a frequency setting means for setting the frequency of the pulse generated by the signal to a predetermined frequency. Therefore, even if the target rotational speed is changed while the motor is rotating, the frequency of the pulse generated by the modulation pulse generating means can be set to a predetermined frequency, so the pulse frequency before the change of the target rotational speed remains. Thus, the motor can be prevented from stepping out.

  Preferably, the modulation pulse generation unit generates a pulse having at least one of a maximum pulse interval and a maximum pulse width. That is, since the pulse generated by the modulation pulse generating means is defined, even if the rotation of the motor changes excessively, step-out can be prevented or overshoot can be reduced.

  Preferably, the apparatus further includes an adding unit that cumulatively adds the rotation speed difference calculated by the difference calculating unit, and the modulation pulse generating unit modulates based on the rotation number difference accumulated by the adding unit. A pulse with the specified pulse width is generated. Therefore, even if the difference in rotational speed with respect to the target rotational speed of the motor suddenly changes, the difference in rotational speed before the sudden change is accumulated, so the time until the rotational speed of the motor suddenly changes and converges to the target rotational speed is accumulated. It can be prevented from becoming longer.

  Preferably, the apparatus further includes rounding means for rounding a difference in rotational speed accumulated by the adding unit, and the modulation pulse generating means is configured to modulate a pulse width modulated based on the rotational speed difference rounded by the rounding means. Generate pulses. In other words, by rounding the cumulative difference of the rotational speeds, an error in the rotational speed difference can be reduced, and the occurrence of uneven rotation of the motor can be reduced.

  Preferably, it further has rounding method changing means for changing the rounding method of the rounding means. Preferably, the rounding method changing unit changes the rounding method of the rounding unit in accordance with at least one of the load, size, and target rotational speed of the motor. Therefore, it is possible to reduce the occurrence of uneven motor rotation according to the motor load, size, target rotational speed, and the like.

  Preferably, the apparatus further includes one or more motors, and the timing adjusting unit stores at least one of a rising timing and a falling timing of a pulse generated by the modulation pulse generating unit for each of the motors. Timing storage means, and the frequency changing means further includes frequency storage means for storing the frequency of the pulse generated by the modulation pulse generation means for each of the motors, and the rounding means is a rounding method. Is further stored for each of the motors. Therefore, it is possible to prevent overshoot, rotation unevenness, or step-out according to the state of each of the plurality of motors.

A second feature of the present invention resides in an image forming apparatus having the motor control device described above.

  According to the present invention, the rotational speed of the motor can be accurately controlled even if the motor is downsized.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an outline of an image forming apparatus 10 according to an embodiment of the present invention.
In this embodiment, the full-color image forming apparatus 10 using the intermediate transfer body 64 such as an intermediate transfer belt will be described as a specific example. However, the present invention is not limited to this, and for example, the intermediate transfer body is not used. Alternatively, the image may be directly transferred from one photoconductor to a recording medium.

  The image forming apparatus 10 includes an image forming apparatus main body 12, and an opening / closing cover 16 that is rotatable about a rotation fulcrum 14 is provided on the upper part of the image forming apparatus main body 12. For example, a one-stage recording medium supply unit 18 is disposed in the lower part of the image forming apparatus main body 12. The recording medium supply unit 18 includes a recording medium supply unit main body 20 and a recording medium supply cassette 22 in which the recording medium is stored. A feed roll 24 for supplying a recording medium from the recording medium supply cassette 22 and a retard roll 26 for scooping the supplied recording medium one by one are arranged in the upper part near the rear end of the recording medium supply cassette 22.

  The conveyance path 28 is a recording medium path from the feed roll 24 to the discharge port 30, and the conveyance path 28 is in the vicinity of the back side (the right side surface in FIG. 1) of the image forming apparatus main body 12 and the recording medium supply unit 18. To a fixing device 90 to be described later. A secondary transfer roll 80 and a secondary transfer backup roll 72, which will be described later, are arranged on the upstream side of the fixing device 90 in the conveyance path 28, and the registration roll 32 is located upstream of the secondary transfer roll 80 and the secondary transfer backup roll 72. Is arranged. In addition, a discharge roll 34 is disposed in the vicinity of the discharge port 30 of the conveyance path 28.

  Therefore, the recording medium fed from the recording medium supply cassette 22 of the recording medium supply unit 18 by the feed roll 24 is rolled by the retard roll 26 and only the uppermost recording medium is guided to the transport path 28 and temporarily registered by the registration roll 32. The toner image is transferred between a secondary transfer roll 80 and a secondary transfer backup roll 72, which will be described later, at a timing, and the transferred toner image is fixed by the fixing device 90. As a result, the air is discharged from the discharge port 30 to the discharge portion 36 provided on the upper portion of the opening / closing cover 16. The discharge portion 36 has a low discharge port portion and is inclined so as to gradually increase toward the front direction (left direction in FIG. 1).

  In the image forming apparatus main body 12, for example, a rotary developing device 38 is disposed at a substantially central portion. The rotary developing device 38 includes developing units 42a to 42d that respectively form toner images of four colors of yellow, yellow, magenta, cyan, and black in the developing unit main body 40. It rotates counterclockwise (counterclockwise in FIG. 1) about the rotary developing device center 44. Each of the developing units 42a to 42d has developing rolls 46a to 46d, and is pressed in the normal direction of the developing unit main body 40 by elastic bodies 48a to 48d such as coil springs.

  The rotary developing device 38 is arranged so that an image carrier 50 made of, for example, a photosensitive member comes into contact therewith, and the developing rolls 46 a to 46 d are not in contact with the image carrier 50, and have one outer periphery. The portion protrudes from the outer periphery of the developing device main body 40 in the radial direction, for example, 2 mm. Further, a tracking roll (not shown) having a diameter slightly larger than the diameter of the developing rolls 46a to 46d is provided at both ends of each of the developing rolls 46a to 46d so as to rotate coaxially with the developing rolls 46a to 46d. Yes. That is, the tracking rolls of the developing rolls 46 a to 46 d are in contact with flanges (not shown) provided at both ends of the image carrier 50, and a predetermined gap is formed between the developing rolls 46 a to 46 d and the image carrier 50. Then, the latent image on the image carrier 50 is developed with each color toner.

Below the image carrier 50, a charging device 52 made of, for example, a charging roll for uniformly charging the image carrier 50 is provided. Further, an image carrier cleaner 54 is in contact with the image carrier 50 on the upstream side of the charging device 52 in the rotation direction of the image carrier 50. The image carrier cleaner 54 includes, for example, a cleaning blade 56 that scrapes off toner remaining on the image carrier 50 after primary transfer, and a toner collection bottle 58 that collects toner scraped off by the cleaning blade 56.
Note that, for example, a rib or the like is formed on the back side (right side in FIG. 1) of the toner collection bottle 58, and is curved to form a part of the conveyance path 28 so that the recording medium is smoothly conveyed.

  Below the rotary developing device 38, an exposure device 60 for writing a latent image on the image carrier 50 charged by the charging device 52 by a light beam such as a laser beam is disposed. Further, an intermediate transfer device 62 is provided above the rotary developing device 38. The toner image visualized by the rotary developing device 38 is primarily transferred at the primary transfer position and conveyed to a secondary transfer position described later.

The intermediate transfer device 62 includes, for example, an intermediate transfer member 64 such as an intermediate transfer belt, a primary transfer roll 66, a wrap-in roll 68, a wrap-out roll 70, a secondary transfer backup roll 72, a scraper backup roll 74, and a brush backup roll 76. Is done. The intermediate transfer body 64 has elasticity, for example, and is stretched approximately flat so as to have a long side and a short side above the rotary developing device 38. The long side on the upper surface side of the intermediate transfer body 64 is stretched so as to be substantially parallel to, for example, the discharge unit 36 provided on the upper portion of the image forming apparatus main body 12. The intermediate transfer member 64 includes a wrap-in roll 68 disposed upstream of the primary transfer roll 66 below the long side of the intermediate transfer member 64, and a wrap-out roll 70 disposed downstream of the primary transfer roll 66. The image bearing member 50 has a primary transfer portion (image bearing member wrap region) that abuts on the image bearing member 50 in a lap shape. The image bearing member 50 is wound around a predetermined range and is driven by the rotation of the image bearing member 50. As described above, the intermediate transfer member 64 is primarily transferred by the primary transfer roll 66 so that the toner images on the image carrier 50 are superposed in the order of, for example, yellow, magenta, cyan, and black. It is conveyed toward the secondary transfer roll 80.
Note that the wrap-in roll 68 and the wrap-out roll 70 are separated from the image carrier 50.

Further, a flat surface portion (short side) is formed on the back side (right side surface in FIG. 1) of the intermediate transfer body 64 by a wrap-out roll 70 and a secondary transfer backup roll 72, and this flat surface portion is subjected to secondary transfer. It faces the conveyance path 28 as a part.
In the secondary transfer portion, the wrap-out roll 70 is arranged so that the intermediate transfer body 64 and the conveyance path 28 are at an angle of 12 °, for example.

  The scraper backup roll 74 assists the scraper 84 described later to scrape off toner remaining on the intermediate transfer body 64 after the secondary transfer, and the brush backup roll 76 removes toner remaining on the intermediate transfer body 64 after the secondary transfer. A brush roll 86 to be described later assists in scraping.

  Above the long side of the intermediate transfer body 64, a sensor 78 such as a reflective photosensor is provided by being fixed to the back surface (inside) of the opening / closing cover 14. The sensor 78 reads a toner patch formed on the intermediate transfer body 64, detects the position of the intermediate transfer body 64 in the rotation direction, and detects the toner density.

  A secondary transfer roll 80 is opposed to the secondary transfer backup roll 72 of the intermediate transfer device 62 with the conveyance path 28 interposed therebetween. That is, the secondary transfer position in the secondary transfer portion is between the secondary transfer roll 80 and the secondary transfer backup roll 72, and the secondary transfer roll 80 is intermediate with the assistance of the secondary transfer backup roll 72. The toner image primarily transferred to the transfer body 64 is secondarily transferred to the recording medium at the secondary transfer position. Here, the secondary transfer roll 80 is separated from the intermediate transfer body 64 while the intermediate transfer body 64 rotates three times, that is, while the toner images of three colors of yellow, magenta, and cyan are transported. When the image is transferred, it comes into contact with the intermediate transfer member 64.

  An intermediate transfer member cleaner 82 is provided in contact with the opposite end of the intermediate transfer member 64 on the side opposite to the image carrier. The intermediate transfer body cleaner 82 is, for example, a scraper 84 that scrapes and cleans toner remaining on the intermediate transfer body 64 after the secondary transfer, a brush roll 86 that scrapes off toner remaining after cleaning by the scraper 84, the scraper 84, and the brush. The toner collection bottle 88 collects the toner scraped off by the roll 86. The scraper 84 is made of, for example, a thin plate made of stainless steel, and is applied with a voltage having a polarity opposite to that of the toner. The brush roll 86 is made of, for example, an acrylic brush that has been subjected to a conductive treatment. Further, while the intermediate transfer member 64 conveys the toner image, the scraper 84 and the brush roll 86 are separated from the intermediate transfer member 64 and come into contact with the intermediate transfer member 64 at a predetermined timing. Has been.

  A fixing device 90 is disposed above the secondary transfer position. The fixing device 90 includes a heating roll 92 and a pressure roll 94, and fixes the toner image secondarily transferred to the recording medium by the secondary transfer roll 80 and the secondary transfer backup roll 72 to the recording medium, and discharge roll Transport toward 34.

  The image forming unit 96 is obtained by integrating the intermediate transfer device 62, the image carrier 50, the charging device 52, the image carrier cleaner 54, and the intermediate transfer member cleaner 82. The image forming unit 96 is disposed immediately below the discharge portion 36 of the opening / closing cover 16, is detachable from the image forming apparatus main body 12, and is attached / detached by opening the opening / closing cover 16.

  Inside the image forming apparatus 10, a control unit 98 that controls each part of the image forming apparatus 10 is provided. Further, the control unit 98 is for a recording medium conveyance system such as the feed roll 24, the retard roll 26 and the resist roll 32, a development system such as the rotary development device 38 having the development rolls 46 a to 46 d, and an intermediate transfer body having the brush roll 86. The number of rotations of motors 100a to 100d (which will be described later with reference to FIG. 2) for applying a rotational force to a cleaner system such as a cleaner 82 and a fixing device system such as a fixing device 90 having a heating roll 92 and a pressure roll 94. Control.

Next, control of the motors 100a to 100d by the control unit 98 will be described.
In FIG. 2, the control unit 98, the motors 100a to 100d, and the periphery thereof are shown. The control unit 98 includes a clock generation unit 101, a CPU 102, and a processing unit 104. The clock generation unit 101 generates a 10 MHz clock signal, for example, and outputs it to the CPU 102 and the processing unit 104. The CPU 102 is connected to the processing unit 104 by a bus and controls the processing unit 104 in synchronization with the clock signal input from the clock generation unit 101. The processing unit 104 includes, for example, four digital processing circuits 106a to 106d, and is integrated into one chip as an ASIC (Application Specific Integrated circuit). Each of the digital processing circuits 106a to 106d is the same circuit, operates in synchronization with a clock signal input from the clock generation unit 101 to the processing unit 104, and each includes a rotation detector (FG: Function Generator) 108a to 108d. The rotation of the motors 100a to 100d is received via 108d, and the motors 100a to 100d are controlled via the drivers 110a to 110d.

The drivers 110a to 110d supply current to the motors 100a to 100d under the control of the digital processing circuits 106a to 106d, and the motors 100a to 100d rotate according to the current supplied from the drivers 110a to 110d, for example. The rotation detectors 108a to 108d include, for example, a Hall element (see FIG. 9) that rotates together coaxially with the rotation shafts of the motors 100a to 100d, a light emitting element and a light receiving element (not shown), and the like. A pulse is generated according to the rotation and output to the digital processing circuits 106a to 106d.
As described above, the motors 100a to 100d apply rotational force to the recording medium conveyance system, the development system, the cleaner system, and the fixing device system, respectively, according to the control of the control unit 98.
Hereinafter, when a plurality of components such as the motors 100a to 100d are not specified, they may be simply abbreviated as “motor 100” or the like.

FIG. 3 shows details of the digital processing circuit 106 and its periphery.
The digital processing circuit 106 includes a counter 112, a register 114, a difference calculation unit 116, an addition unit 118, a multiplication unit 120, and a modulation pulse generation unit 122. The counter 112 measures the pulse input from the rotation detector 108 by counting the pulse width in synchronization with the clock signal, and outputs it to the difference calculation unit 116 and the CPU 102 as a count value (digital data). . For example, as shown in FIG. 4, the rotation detector 108 generates a pulse having a cycle of 500 Hz and a duty ratio of 50%, and a 10 MHz clock is transferred from the clock generation unit 101 to the digital processing circuit 106 of the processing unit 104 (FIG. 2). When the signal is input, the counter 112 counts a pulse width of 1 mS (half cycle) in synchronization with the 10 MHz clock signal, and outputs a count value 10000 (decimal number) to the CPU 102 and the difference calculation unit 116. . However, the counter 112 converts the count value into, for example, 16-bit digital data and outputs it to the difference calculation unit 116.

The counter 112 outputs individual counts to the CPU 102 in synchronization with the clock signal. Therefore, the CPU 102 can monitor the load fluctuation and abnormal rotation of the motor 100 by the individual counts input from the counter 112.
FIG. 5 shows the timing until the CPU 102 determines that the rotation state of the motor 100 is abnormal. As shown in FIG. 5, the pulse width of the pulse output from the rotation detector 108 with respect to the count value (set maximum count number) corresponding to the maximum pulse width (design maximum value) to be output by the rotation detector 108. Is long, the motor 100 is in a state outside the range set by design (for example, rotation stopped). Here, the CPU 102 determines that the rotation of the motor 100 is abnormal when individual counts input from the counter 112 match the set abnormal count number stored in a memory (not shown) or the like. Then, a motor error signal is output to a user interface (not shown) such as a touch panel provided in the image forming apparatus 10.

The register 114 stores an initial value, a setting value, and the like input via a user interface (not shown) and the CPU 102, and outputs a predetermined value to each unit constituting the digital processing circuit 106. The values stored in the register 114 include the target frequency (target rotational speed) of the motor 100, a start signal that defines a pulse at the start of the motor 100, a feedback rate (FB rate) to be described later, and settings for the modulation pulse generator 122. There is a value. The register 114 outputs a pulse width value (count value) corresponding to the target frequency of the motor 100 to the difference calculation unit 116 as 16-bit data, and a pulse at the time of starting the motor 100 (described later with reference to FIG. 6). Is output to the adder 118, the setting value for the modulation pulse generator 122 is output to the modulation pulse generator 122 by the setting control signal, and the FB rate is output to the multiplier 120. . The FB rate is defined by 1 / 2n (n is an integer from 1 to 16) in order to round an output value of an adder 118 described later by, for example, multiplication.
The value stored in the register 114 can be changed via a user interface (not shown) or the counter 112 and the CPU 102.

  The difference calculation unit 116 compares the count value input from the counter 112 with the pulse width value (count value) corresponding to the target frequency input from the register 114, and the rotation frequency detected by the rotation detector 108. The difference between the (rotational speed) and the target frequency is calculated and output to the adder 118. The difference between the detected rotation frequency and the target frequency is a difference indicating that the detected rotation frequency is slower than the target frequency (a difference on the plus side) and a difference indicating that the detected rotation frequency is faster than the target frequency. (Minus side difference), and each is output to the adder 118 as 18-bit data. The plus side difference is a value of 0 or more, and the minus side difference is a value of 0 or less. That is, when the detected rotation frequency is slower than the target frequency, the minus difference is 0, and when the detected rotation frequency is faster than the target frequency, the plus difference is 0. Has been.

  When the plus side difference and the minus side difference are input from the difference calculating unit 116, the adder 118 cumulatively adds the plus side difference and the minus side difference together to the multiplication unit 120 as 24-bit data. Output. However, when the start signal is input from the register 114, that is, in a predetermined period (initial control period) at the start of the motor 100, the adder 118 and the difference on the plus side input from the difference calculator 116 and A predetermined value corresponding to the activation signal is output to the multiplication unit 120 instead of the result of cumulative addition of the minus side difference.

  The multiplier 120 multiplies the 24-bit data input from the adder 118 and the FB rate (1 / 2n) input from the register 114, and outputs the result to the modulation pulse generator 122, for example, as 20-bit data. . That is, the multiplication unit 120 rounds the 24-bit data input from the addition unit 118 by dividing by 2n, and outputs the result to the modulation pulse generation unit 122.

  The modulation pulse generation unit 122 generates a pulse width-modulated pulse based on the 20-bit data input from the multiplication unit 120 and the setting control signal (predetermined setting) input from the register 114, and outputs the pulse to the driver 110. To do. However, when the motor 100 is activated, a predetermined pulse may be output in a predetermined period (initial control period) by a setting control signal input from the register 114. For example, as shown in FIG. 6, during the initial control period, the modulation pulse generator 122 outputs a pulse having a duty ratio of less than 50% at least once so that the rotation frequency exceeds the target frequency of the motor 100. Reduce the shoot.

  As described above, the digital processing circuits 106a to 106d are the same circuit. On the other hand, the registers 114 of the digital processing circuits 106a to 106d store individual initial values and setting values under the control of the CPU 102, for example. That is, by storing individual initial values and setting values in the registers 114 of the digital processing circuits 106a to 106d, the control unit 98 can perform different controls on the motors 100a to 100d. For example, as shown in FIG. 7, the digital processing circuit 106 changes the initial value and setting value of the register 114 with respect to a pulse input from the rotation detector 108 to the digital processing circuit 106. Pulses with different pulse widths can be output. Therefore, even when the loads of the motors 100a to 100d are different, the digital processing circuits 106a to 106d prevent the motors 100a to 100d from vibrating and stepping out according to the loads of the motors 100a to 100d, and the rotational speed. And responsiveness can be controlled.

Next, the operation of the digital processing circuit 106 will be described.
When the motor 100 rotates, the rotation detector 108 generates a pulse corresponding to the rotation of the motor 100 and outputs it to the counter 112. The counter 112 counts a count value corresponding to the pulse width of the pulse input from the rotation detector 108 and outputs the count value to the difference calculation unit 116. The difference calculation unit 116 compares the count value input from the counter 112 with the count value corresponding to the target frequency of the motor 100 input from the register 114, and calculates a plus-side difference and a minus-side difference.

  The adder 118 calculates the 24-bit data by accumulatively adding the plus-side difference and the minus-side difference calculated by the difference calculating unit 116, and outputs the data to the multiplying unit 120. The multiplier 120 rounds the 24-bit data input from the adder 118 by the FB rate input from the register 114 and outputs the rounded data to the modulation pulse generator 122 as 20-bit data.

The modulation pulse generator 122 generates a pulse width modulated pulse based on the 20-bit data input from the multiplier 120 and the setting control signal input from the register 114, and outputs the pulse to the driver 110. The driver 110 drives the motor 100 according to the pulse input from the modulation pulse generator 122.
In this way, the digital processing circuit 106 generates a pulse width modulated pulse from the pulse corresponding to the rotation of the motor 100 detected by the rotation detector 108, and the rotation of the motor 100 is controlled by this pulse width modulated pulse. ing. That is, the motor 100 is PWM (Pulse Width Modulation) controlled by the controller 98 (FIG. 2).

  However, when the motor 100 is started, the register 114 outputs a start signal to the adder 118, and a predetermined pulse is output from the modulation pulse generator 122 to the driver 110 to drive the motor 100. Further, the CPU 102 monitors the rotation state of the motor 100 based on the count value input from the counter 112, and when the motor 100 is in an abnormal state, for example, the setting value stored in the register 114 is displayed. change.

Next, a modified example of the control of the motor 100 by the control unit 98 will be described.
FIG. 8 shows a first modification of the method in which the counter 112 counts the count value (data) with respect to the pulses output from the rotation detector 108. As shown in FIG. 8, for a pulse with a duty ratio of 50% output from the rotation detector 108, the counter 112 measures each pulse width and pulse interval by counting them in synchronization with the clock signal. Value (digital data). Thus, the counter 112 can count two types of rotation speed data for the pulses output from the rotation detector 108 by counting the data X from the pulse width and counting the data Y from the pulse interval. It is possible to count twice as many data as the number of pulses.

  In FIG. 9, a Hall element 124 having three holes is illustrated. For example, when the Hall element 124 is provided in the rotation detector 108 (FIGS. 2 and 3) and the rotation shaft 126 of the Hall element 124 rotates together with the rotation shaft of the motor 100, when the motor 100 rotates once, the rotation detector 108 Three pulses are output. Here, as shown in FIG. 8, when the counter 112 counts the pulse width and the pulse interval in synchronization with the clock signal with respect to the pulse output from the rotation detector 108, the data for the rotation of the motor 100 is 6. Can be counted. In this way, the number of rotation speed data for controlling the rotation speed of the motor can be increased more than the number of pulses, and the control unit can be used even when the number of pulses from the rotation detector 108 accompanying the rotation of the motor 100 is small. 98 can accurately control the rotation of the motor 100.

  FIG. 10 shows a second modification of the method in which the counter 112 counts the count value (data) with respect to the pulses output from the rotation detector 108. As shown in FIG. 10, for the pulses output from the rotation detector 108, the counter 112 counts the count value (data) with respect to the pulse width by, for example, sequentially averaging the pulse width every three pulses, Diffuse mechanical errors. For the pulses output from the rotation detector 108, the counter 112 may count the count value with respect to the pulse interval by sequentially averaging the pulse intervals, for example, every three pulses, or the pulse width and the pulse You may make it count a count value combining the thing which averaged each space | interval sequentially.

FIG. 11 shows an adjustment example of pulses that the digital processing circuit 106 adjusts in the initial control period with respect to the difference in the load of the motor 100. As illustrated in FIG. 11, the digital processing circuit 106 adjusts the rising timing of the pulse generated by the modulation pulse generation unit 122 by outputting a setting control signal from the register 114 to the modulation pulse generation unit 122, for example. For example, when the load on the motor 100 is large, the rising timing of the pulse is advanced to avoid the step-out of the motor 100. When the load on the motor 100 is small, the pulse rising timing is delayed to reduce the overshoot of the rotational frequency with respect to the target frequency of the motor 100.
Further, the digital processing circuit 106 may adjust the falling timing of the pulse generated by the modulation pulse generation unit 122, or adjust the pulse width by adjusting the rising timing and the falling timing in combination. Also good.

FIG. 12 shows pulses that the digital processing circuit 106 outputs to the driver 110 when the target rotational speed of the motor 100 is switched while the motor 100 is rotating.
As shown in FIG. 12, for example, when the target rotational speed of the motor 100 is switched while the motor 100 is rotating, the digital processing circuit 106 outputs a setting control signal from the register 114 to the modulation pulse generator 122. The pulse generated by the modulation pulse generator 122 is replaced with a predetermined pulse corresponding to the switched target rotation speed. Therefore, when the target rotational speed is switched, it is possible to prevent the motor 100 from stepping out due to the output of data processed by the adding unit 118 and the like before the target rotational speed is switched.

FIG. 13 shows an example of pulses output from the digital processing circuit 106 when the maximum pulse interval of pulses output from the digital processing circuit 106 is defined.
Based on the settings stored in the register 114, the modulation pulse generator 122 generates a pulse having a minimum pulse width and a maximum pulse interval. For example, as shown in FIG. 13, when the pulse output from the rotation detector 108 indicates an increase in the rotation frequency, the maximum pulse interval of the pulse output from the digital processing circuit 106 is defined. The motor 100 is prevented from stepping out by increasing the pulse interval of the pulses output from the modulation pulse generator 122 in order to lower the rotation frequency.

  FIG. 14 shows an example of a pulse output from the digital processing circuit 106 when the maximum pulse width of the pulse output from the digital processing circuit 106 is defined. Based on the settings stored in the register 114, the modulation pulse generator 122 generates a pulse with a maximum pulse width. For example, as shown in FIG. 14, when the pulse output from the rotation detector 108 indicates a decrease in the rotation frequency, the maximum pulse width of the pulse output from the digital processing circuit 106 is defined. It is possible to reduce the occurrence of an overshoot of the rotation frequency with respect to the target frequency due to an increase in the pulse width of the pulse output from the modulation pulse generator 122 in order to increase the rotation frequency.

  FIG. 15 shows a modified example of timing until the CPU 102 determines that the rotation state of the motor 100 is abnormal. When the count value counted by the counter 112 is outside the range set by design with respect to the pulse output from the rotation detector 108, the CPU 102 determines that the motor 100 is rotating in a defective manner. For example, when the rotation frequency of the motor 100 is excessively higher than the target frequency, the CPU 102 determines that the motor 100 is rotating poorly. As shown in FIG. 15, when the pulse output from the rotation detector 108 indicates a defective rotation of the motor 100, pulses indicating the defective rotation are continuously generated, and the number of pulses indicating the defective rotation is illustrated. When the predetermined number stored in the memory or the like reaches the predetermined number, the CPU 102 determines that the rotation of the motor 100 is abnormal, and displays it on a user interface (not shown) such as a touch panel provided in the image forming apparatus 10. In response, a motor error signal is output.

1 is a side view illustrating an outline of an image forming apparatus according to an embodiment of the present invention. It is a block diagram which shows a control part, a motor, and its periphery. It is a block diagram which shows the detail of a digital processing circuit, and its periphery. It is a schematic diagram which shows the state in which a counter measures the count value corresponding to a pulse width synchronizing with a clock signal. It is a timing chart which shows the timing until CPU judges that the rotation state of a motor is abnormal. It is a schematic diagram which shows the state which reduces the overshoot of the rotational frequency with respect to the target frequency of a motor with the pulse output in an initial stage control period. It is a schematic diagram which shows the pulse which a digital processing circuit outputs with respect to the pulse input into a digital processing circuit from a rotation detector. It is a timing chart which shows the 1st modification of the method in which a counter counts a count value (data) with respect to the pulse which a rotation detector outputs. It is a front view which shows the Hall element which has three hall | holes. It is a timing chart which shows the 2nd modification of the method in which a counter counts a count value (data) with respect to the pulse which a rotation detector outputs. It is a graph which shows the adjustment example of the pulse which a digital processing circuit adjusts in an initial stage control period with respect to the difference in the load of a motor. It is a timing chart which shows the pulse which a digital processing circuit outputs to a driver when the target number of rotations of a motor is changed while the motor is rotating. It is a timing chart which shows the pulse output from a digital processing circuit, when the maximum pulse interval of the pulse which a digital processing circuit outputs is prescribed | regulated. It is a timing chart which shows the pulse output from a digital processing circuit when the maximum pulse width of the pulse which a digital processing circuit outputs is prescribed | regulated. It is a timing chart which shows the modification of the timing until CPU judges that the rotation state of a motor is abnormal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 38 Rotary developing device 50 Image carrier 52 Charging device 54 Image carrier cleaner 60 Exposure device 62 Intermediate transfer device 64 Intermediate transfer member 80 Secondary transfer roll 90 Fixing device 96 Image forming unit 98 Control units 100a to 100d Motor 101 Clock generator 102 CPU
104 processing units 106a to 106d digital processing circuits 108a to 108d rotation detectors 110a to 110d driver 112 counter 114 register 116 difference calculation unit 118 addition unit 120 multiplication unit 122 modulation pulse generation unit 124 Hall element

Claims (15)

A motor,
A rotation detector that generates a pulse according to the rotation of the motor and detects the rotation of the motor;
Averaging means for averaging the pulse widths of the plurality of pulses generated by the rotation detector and the pulse intervals of the plurality of pulses generated by the rotation detector;
Counting means for counting at least two types of rotation speed data relating to the motor based on pulses having a pulse width and a pulse interval averaged by the averaging means;
Based on this counting means each of the at least two rotational speed data is counted, and the difference calculating means for calculating a difference between the rotational speed to the target rotational speed of the motor,
A modulation pulse generating means for generating a pulse having a pulse width modulated based on the difference in rotation speed calculated by the difference calculating means;
A motor control device comprising: drive means for driving the motor based on the pulse generated by the modulation pulse generation means. It said averaging means, according to claim 1, characterized in that sequentially averaging at least one of the plurality of pulses of the pulse interval in which the pulse widths of the plurality of pulses rotation detector is generated and the rotation detector is generated The motor control apparatus described . 3. The motor control device according to claim 1, wherein the difference calculating unit calculates a rotation speed difference including a binary value of a value indicating a difference of 0 or more and a value indicating a difference of 0 or less. When the motor is started, the modulated pulse generating means according to any one of claims 1 to 3, further comprising a timing adjusting means for adjusting at least one of the rise timing and fall timing of the pulse which is generated Motor control device. The timing adjusting unit adjusts at least one of a rising timing and a falling timing of a pulse generated by the modulation pulse generating unit according to at least one of a load, a size, and a target rotational speed of the motor. The motor control device according to claim 4 . The motor control device according to any one of claims 1 to 5, further comprising a frequency changing means for changing the frequency of the pulses generated by said modulation pulse generation means. The motor control according to claim 6 , wherein the frequency changing unit changes a frequency of a pulse generated by the modulation pulse generating unit according to at least one of a load, a size, and a target rotational speed of the motor. apparatus. A target rotational speed changing means for changing the target rotational speed of the motor; and a frequency of a pulse generated by the modulation pulse generating means when the target rotational speed is changed while the motor is rotating by the target rotational speed changing means. the motor control device according to any one of claims 1 to 7, further comprising a frequency setting means for setting a predetermined frequency. The modulated pulse generating means, the motor control device according to any one of claims 1 to 8, characterized in that to produce a pulse which is defined at least one of the maximum pulse interval and the maximum pulse width. An addition unit that cumulatively adds the rotation speed difference calculated by the difference calculation unit; and the modulation pulse generation unit outputs a pulse having a pulse width modulated based on the rotation number difference accumulated by the addition unit. generating a motor control device according to any one of claims 1 to 9, characterized in that. And further comprising a rounding means for rounding a difference in rotational speed cumulatively added by the adder, wherein the modulation pulse generating means generates a pulse having a pulse width modulated based on the rotational speed difference rounded by the rounding means. The motor control device according to claim 10 . The motor control device according to claim 11 , further comprising a rounding method changing unit that changes a rounding method of the rounding unit. 13. The motor control apparatus according to claim 12 , wherein the rounding method changing unit changes the rounding method of the rounding unit according to at least one of a load, a size, and a target rotation speed of the motor. The motor further includes one or more motors, and the timing adjusting unit further includes a timing storage unit that stores at least one of a rising timing and a falling timing of a pulse generated by the modulation pulse generating unit for each of the motors. The frequency changing means further includes a frequency storage means for storing the frequency of the pulse generated by the modulation pulse generating means for each of the motors, and the rounding means is a rounding method for each of the motors. 14. The motor control device according to claim 10 , further comprising a rounding method storage means for storing the data. An image forming apparatus having a motor control device according to any of claims 1 to 14.

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