JP2010098784A - Motor control device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor control device capable of detecting overload of a DC brushless motor without installing a current detecting circuit. <P>SOLUTION: An ACC/DEC module 205 controlled by a CPU 201 compares the frequency of a rotation detection signal proportional to the rotation speed of the motor with a target frequency for driving the motor at a predetermined speed. When determining that the frequency of the rotation detection signal exceeds the target frequency, the ACC/DEC module 205 compares the pulse width of an acceleration signal that is output for accelerating the motor with a predetermined pulse width. When determining that the pulse width of the acceleration signal exceeds the predetermined pulse width, the ACC/DEC module 205 stops the rotation of the motor or causes the motor to shift to a low speed mode. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a motor control device that controls a DC brushless motor and an image forming apparatus such as a laser beam printer or a copying machine.

  Conventionally, in a laser beam printer and a copying machine, a DC brushless motor is used for every application because of its high rotational stability and long life.

  In particular, in a color image forming apparatus, a DC brushless motor is increasingly used from the viewpoint of high torque and high rotation speed. Recently, it has become possible to control the acceleration (acceleration) / dexel (deceleration) of a DC brushless motor.

  Unlike a stepping motor, a DC brushless motor has an advantage that it can rotate without stepping out even in an overload state. However, if the operation continues without stopping in an overload state, the gear driving the DC brushless motor may be damaged in some cases.

  For this reason, it is conceivable that the strength of the gear is physically increased, but in this case, the cost is increased.

As a technique for detecting an overload state and preventing gear breakage, a technique for detecting a driving current of a motor has been proposed (see Patent Document 1). As another technique, a technique for detecting a driving voltage of a motor has been proposed (see Patent Document 2).
JP 2000-245182 A JP-A-7-67385

  However, in the technique described in Patent Document 1, a circuit for detecting a current value must be newly added to the control unit side, which leads to an increase in size and cost of the device.

  In the technique described in Patent Document 2, it is necessary to output a signal for detecting a voltage from the motor drive circuit, which leads to an increase in cost. For this reason, it is necessary to detect an overload state with a normal control signal without increasing the cost.

  An object of the present invention is to provide a motor control device and an image forming apparatus that can detect an overload of a DC brushless motor without providing a current detection circuit or the like.

  In order to achieve the above object, a motor control device according to claim 1 is a motor control device for controlling a DC brushless motor, wherein a pulse width of an acceleration signal outputted for accelerating the DC brushless motor and a predetermined pulse are used. Comparing means for comparing the width, and control means for stopping the rotation of the DC brushless motor when the comparing means determines that the pulse width of the acceleration signal exceeds the predetermined pulse width. Features.

  The motor control device according to claim 3 is a motor control device for controlling a DC brushless motor, comparing means for comparing a pulse width of an acceleration signal output for accelerating the DC brushless motor with a predetermined pulse width; And a control means for causing the DC brushless motor to shift to a low speed mode when the comparison means determines that the pulse width of the acceleration signal exceeds the predetermined pulse width.

  6. The motor control apparatus according to claim 5, wherein a frequency of a rotation detection signal proportional to a rotation speed of the DC brushless motor and a target frequency for rotating the DC brushless motor at a predetermined speed in the motor control apparatus for controlling the DC brushless motor. , And the acceleration output to accelerate the DC brushless motor when it is determined by the first comparison means that the frequency of the rotation detection signal exceeds the target frequency. A second comparing means for comparing a pulse width of the signal with a predetermined pulse width; and when the second comparing means determines that the pulse width of the acceleration signal exceeds the predetermined pulse width, the DC And a control means for stopping the rotation of the brushless motor.

  The motor control device according to claim 7, wherein the motor control device controls a DC brushless motor, the frequency of a rotation detection signal proportional to the rotation speed of the DC brushless motor, and a target frequency for rotating the DC brushless motor at a predetermined speed. , And the acceleration output to accelerate the DC brushless motor when it is determined by the first comparison means that the frequency of the rotation detection signal exceeds the target frequency. A second comparing means for comparing a pulse width of the signal with a predetermined pulse width; and when the second comparing means determines that the pulse width of the acceleration signal exceeds the predetermined pulse width, the DC And a control means for shifting the brushless motor to the low speed mode.

  The motor control device according to claim 9 is a motor control device for controlling a DC brushless motor, comparing means for comparing a pulse width of an acceleration signal output for accelerating the DC brushless motor with a predetermined pulse width; Limiting means for limiting the pulse width of the acceleration signal to the predetermined pulse width when the comparing means determines that the pulse width of the acceleration signal exceeds the predetermined pulse width. To do.

  The motor control device according to claim 10, wherein the motor control device controls a DC brushless motor, and a frequency of a rotation detection signal proportional to a rotation speed of the DC brushless motor and a target frequency for rotating the DC brushless motor at a predetermined speed. , And the acceleration output to accelerate the DC brushless motor when it is determined by the first comparison means that the frequency of the rotation detection signal exceeds the target frequency. A second comparing means for comparing the pulse width of the signal with a predetermined pulse width; and the acceleration when the pulse width of the acceleration signal is determined to exceed the predetermined pulse width by the second comparing means. And limiting means for limiting the pulse width of the signal to the predetermined pulse width.

  An image forming apparatus according to an eleventh aspect includes the motor control device according to any one of the first, third, fifth, seventh, ninth, and tenth aspects.

  According to the motor control device of the present invention, it is possible to detect the overload of the DC brushless motor without providing a current detection circuit or the like.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.

  The image forming apparatus in FIG. 1 is a color image forming apparatus having an electrophotographic tandem type intermediate transfer belt.

  The image forming apparatus includes an image forming unit 1Y that forms a yellow image, an image forming unit 1M that forms a magenta image, an image forming unit 1C that forms a cyan image, and a black image. The image forming unit 1Bk to be formed includes four image forming units.

  These four image forming units 1Y, 1M, 1C, and 1Bk are arranged in a line at regular intervals. Furthermore, a cassette 17 and a manual feed tray 20 are arranged below the paper, a paper transport path 18 is arranged vertically, and a fixing unit 16 is provided above the cassette.

  Next, each unit will be described in detail.

  Each of the image forming units 1Y, 1M, 1C, and 1Bk is provided with drum-type electrophotographic photosensitive members (hereinafter referred to as photosensitive drums) 2a, 2b, 2c, and 2d as image carriers. Around each photosensitive drum 2a, 2b, 2c, 2d, there are primary chargers 3a, 3b, 3c, 3d, developing devices 4a, 4b, 4c, 4d, transfer rollers 5a, 5b, 5c, 5d as transfer means, Drum cleaner devices 6a, 6b, 6c and 6d are respectively arranged.

  A laser exposure device 7 is installed below the primary chargers 3a, 3b, 3c, and 3d and the developing devices 4a, 4b, 4c, and 4d.

  Each of the photosensitive drums 2a, 2b, 2c, and 2d is a negatively charged OPC photosensitive member having a photoconductive layer on an aluminum drum base, and a predetermined process speed in a clockwise direction by a driving device (not shown). Is driven to rotate.

  The primary chargers 3a, 3b, 3c, and 3d as primary charging means bring the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d to a predetermined negative potential by a charging bias applied from a charging bias power source (not shown). Charge uniformly.

  The laser exposure device 7 disposed below the photosensitive drum 2 includes laser light emitting means that emits light corresponding to time-series electric digital pixel signals of given image information, a polygon lens, a reflection mirror, and the like.

  The laser exposure device 7 exposes the photosensitive drums 2a, 2b, 2c, and 2d to expose the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d charged by the primary chargers 3a, 3b, 3c, and 3d. Then, an electrostatic latent image of each color corresponding to the image information is formed.

  Each of the developing devices 4a, 4b, 4c, and 4d stores yellow toner, cyan toner, magenta toner, and black toner, respectively. Each developing device 4a, 4b, 4c, 4d develops a toner image (visible image) by attaching each color toner to each electrostatic latent image formed on each photosensitive drum 2a, 2b, 2c, 2d. ).

  The transfer rollers 5a, 5b, 5c, and 5d as primary transfer units are disposed so as to be in contact with the photosensitive drums 2a, 2b, 2c, and 2d via the intermediate transfer belt 8 at the primary transfer portions 32a to 32d. Yes. The transfer rollers 5a, 5b, 5c, and 5d sequentially transfer and superimpose the toner images on the respective photosensitive drums 2 onto the intermediate transfer belt 8.

  The drum cleaners 6a, 6b, 6c, and 6d are configured by a cleaning blade or the like, and scrape off residual transfer toner remaining on the photosensitive drum 2 during the primary transfer from the photosensitive drum 2 to clean the surface of the photosensitive drum 2. .

  The intermediate transfer belt 8 is disposed on the upper surface side of each of the photosensitive drums 2a, 2b, 2c, and 2d, and is stretched between the secondary transfer counter roller 10 and the tension roller 11. The secondary transfer counter roller 10 is disposed in the secondary transfer portion 34 so as to be in contact with the secondary transfer roller 12 via the intermediate transfer belt 8.

  The intermediate transfer belt 8 is made of a dielectric resin such as a polycarbonate, a polyethylene terephthalate resin film, a polyvinylidene fluoride resin film, or the like. The image transferred to the intermediate transfer belt 8 is transferred to a sheet conveyed from a sheet feeding unit described later in the secondary transfer unit 34.

  Outside the intermediate transfer belt 8 and in the vicinity of the tension roller 11, a belt cleaning device 13 for removing and collecting the transfer residual toner remaining on the surface of the intermediate transfer belt 8 is installed.

  Image formation with each toner is performed by the process described above.

  The paper feed unit includes a cassette 17 for storing paper P, a manual feed tray 20, and a pickup roller (not shown) for feeding the paper P one by one in the cassette 17 or from the manual feed tray 20.

  The paper feed unit also transfers the paper P to the secondary transfer area in accordance with the paper feed roller for transporting the paper P delivered from each pickup roller to the registration rollers, the transport path 18, and the image formation timing of the image forming unit 1. A registration roller 19 is provided for feeding to the printer.

  The fixing unit 16 includes a fixing film (fixing roller) 16a having a heat source such as a ceramic substrate having a heater disposed therein, and a pressure roller 16b (a heat source applied to the roller) that is pressed with the fixing film 16a interposed between the substrate and the fixing film 16a. In some cases).

  Further, on the upstream side of the fixing unit 16, there is a conveyance guide 35 for guiding the paper P to the nip portion 31 of the roller pair, and on the downstream side of the fixing unit 16, the paper P discharged from the fixing unit 16. An outer paper discharge roller 21 is provided for guiding the printer to the outside. Further, there is a paper discharge tray 22 on the downstream side of the outer paper discharge roller 21.

  FIG. 2 is a block diagram of a controller unit in the image forming apparatus of FIG.

  In the controller unit 200, the CPU 201 controls the entire image forming apparatus, and sequentially reads and executes a program from a read-only memory 203 (ROM) that stores a control procedure (control program) of the apparatus main body.

  The address bus and data bus of the CPU 201 are connected to each load via a bus driver / address decoder 202. A random access memory (RAM) 204 is a main storage device used as a storage for input data, a working storage area, or the like.

  The I / O 206 is a key input by the operator, and various loads such as an operation panel 216 that displays the state of the apparatus using liquid crystal and LEDs, a stepping motor 207 that drives the paper feed system, the transport system, and the optical system. Connected to. The I / O 206 is connected to loads such as a clutch 208, a solenoid 209, and a paper detection sensor 210 for detecting the conveyed paper.

  The developing device 4 is provided with a toner sensor 211 that detects the amount of toner, and an output signal thereof is input to the I / O 206. Further, signals from switches 212 for detecting the home position of each load, the open / closed state of the door, and the like are also input to the I / O 206.

  The high voltage unit 213 outputs a high voltage to the primary charger 3, the developing device 4, the transfer roller 5, and the secondary transfer roller 12 in accordance with an instruction from the CPU 201. The heater 217 is formed of a base material on which PTC elements are arranged, and an AC voltage is supplied by an on / off signal.

  The ACC / DEC module 205 receives the FG signal from the DC brushless motor 220 and outputs an ACC (acceleration) / DEC (deceleration) signal. The DC brushless motor 220 drives the photosensitive drum 2, the developing device 4, the intermediate transfer belt 8, and the fixing unit 16. These loads driven by the DC brushless motor 220 may become heavy due to the state in the image forming apparatus, aging, or the like.

  The image processing unit 221 is also equipped with a CPU and is connected to the CPU 201 via a serial signal or the like via the PWM 215 and exchanges output timing and the like to the engine unit. When an image signal output from the connected personal computer 222 or the like is input, image processing is performed and image data is output to the engine unit.

  According to the image data from the image processing unit 221, the laser light output from the laser exposure device 7 irradiates and exposes the photosensitive drum 2, and the light emission state is detected by the beam detection sensor 214 which is a light receiving sensor in the non-image region. The An output signal from the beam detection sensor is input to the I / O 206.

  Next, an image forming operation of the engine unit of the color image forming apparatus described above will be described.

  When an image formation start signal is issued from the personal computer 222 connected to the image forming apparatus, the paper feeding operation is started from the selected cassette 17 or the manual feed tray 20.

  For example, the case where paper is fed from the cassette 17 will be described. First, the paper P is sent out one by one from the cassette 17 by the pickup roller. Then, the paper P is guided between the conveyance paths 18 and conveyed to the registration rollers 19.

  At that time, the registration roller 19 is stopped, and the leading edge of the paper hits the nip portion. Thereafter, the registration roller 19 starts rotating based on a timing signal at which the image forming unit 1 starts image formation.

  The rotation timing is set so that the paper P and the toner image primarily transferred from the image forming unit 1 onto the intermediate transfer belt 8 coincide with each other in the secondary transfer unit 34.

  On the other hand, in the image forming unit 1, when an image forming operation start signal is issued, an electrostatic latent image is formed on the photosensitive drum 2 of each color. The image forming timing in the sub-scanning direction is determined according to the distance between the image forming units in order from the photosensitive drum (Y in the present embodiment) that is the most upstream in the rotation direction of the intermediate transfer belt 8. Is done.

  As for the writing timing of each photosensitive drum 2 in the main scanning direction, a pseudo BD sensor signal is generated by using one BD sensor signal (arranged in BK in the present embodiment) by a circuit operation (not shown). Control.

  The formed electrostatic latent image is developed by the process described above. The toner image formed on the photosensitive drum 2a at the most upstream is primarily transferred to the intermediate transfer belt 8 in the primary transfer region by the transfer roller 5a to which a high voltage is applied.

  The primarily transferred toner image is conveyed to the next transfer roller 5b. In this case, image formation is performed by delaying the time during which the toner image is conveyed between the image forming portions by the timing signal described above, and the next toner image is transferred with the resist aligned on the previous image. It will be.

  Thereafter, the same process is repeated, and eventually the four color toner images are primarily transferred onto the intermediate transfer belt 8.

  Thereafter, when the paper P enters the secondary transfer unit 34 and contacts the intermediate transfer belt 8, a high voltage is applied to the secondary transfer roller 12 in accordance with the passage timing of the paper P. Then, the four color toner images formed on the intermediate transfer belt 8 by the process described above are transferred onto the surface of the paper P.

  After the secondary transfer, the paper P is accurately guided to the nip portion 31 by the conveyance guide 35. The toner image is fixed on the surface of the paper by the heat of the fixing film 16a and the pressure roller 16b and the pressure of the nip. Thereafter, the paper P is conveyed by the outer paper discharge roller 21, and the paper P is discharged to the paper discharge tray 22 to complete a series of image forming operations.

  In the present embodiment, yellow, magenta, cyan, and black are arranged in this order from the upstream side of the image forming unit 1, but this is determined by the characteristics of the apparatus and is not limited to this.

  FIG. 3 is a control block diagram of the DC brushless motor in FIG.

  The DC brushless motor of the present embodiment is a three-phase DC brushless motor 220, and has three coils 315 to 317 of U, V, and W phases and a rotor. Three Hall elements 318 to 320 are provided for detecting the rotational position of the rotor, and their outputs are input to the motor control IC 301.

  The three coils 315 to 317 are connected to the midpoints of the high-side FETs 302 to 304 and the low-side FETs 305 to 307, respectively.

  Accordingly, the motor control IC 301 sequentially turns on / off the FETs 302 to 307 based on the rotational position information of the rotor detected by the Hall elements 318 to 320, and causes the coils 315 to 317 to flow to rotate the rotor.

  The current flowing through the DC brushless motor 220 is converted into a voltage by a current detection (detection) resistor 324, and the motor control IC 301 is turned on when the high-side FETs 302 to 304 are turned on so that the detected current value is equal to or less than a predetermined current value. PWM control is performed.

  Further, fine multipolar magnetization is applied to the end face of the rotor, and a rectangular wave print pattern (FG pattern) 325 is provided at a position facing it. When the rotor rotates, an AC voltage is induced at both ends of the FG pattern 325 and is detected by the motor control IC 301.

  Since the detected frequency of the AC voltage is proportional to the speed of the rotor, it is shaped into a digital waveform in the motor control IC 301 and transmitted to the ACC / DEC module 205 as an FG signal representing the speed of the motor.

  The ACC / DEC module 205 compares the frequency of the FG signal received from the DC brushless motor 220 with the target frequency of the FG signal calculated from the set target speed. The ACC / DEC module 205 transmits an acceleration (ACC) signal to the motor control IC 301 if the actual speed obtained from the FG signal received with respect to the target speed is slow, and a deceleration (DEC) signal if the actual speed is fast.

  The motor control IC 301 performs acceleration or deceleration of the DC brushless motor 220 in accordance with the received signal, and controls to rotate at a constant speed at the target speed.

  FIG. 4 is a timing chart of speed control of the DC brushless motor in FIG.

  The ACC / DEC module 205 receives the FG signal from the DC brushless motor 220. The frequency of the FG signal changes in proportion to the speed.

  When the speed of the DC brushless motor 220 is high, the detection time of the FG signal is shortened so that the frequency is small. When the speed is low, the detection time of the FG signal is long and the frequency is large.

  The ACC / DEC module 205 has a target frequency of the FG signal corresponding to the target speed, and the FG signal from the DC brushless motor 220 is compared with the frequency of the target speed.

  When the speed of the DC brushless motor 220 is slower than the target speed, the ACC signal is output by the difference and accelerated. Conversely, when the speed of the DC brushless motor 220 is higher than the target speed, the DEC signal is output by the difference and decelerated.

  That is, the pulse width of the ACC signal or DEC signal increases as the difference in speed increases. The ACC / DEC signal is calculated and output in synchronization with the internal CLK of the ACC / DEC module 205.

  FIG. 5 is a flowchart showing the procedure of the first embodiment of the DC brushless motor control process executed by the controller unit of FIG. 2 and the control block of the DC brushless motor of FIG.

  Hereinafter, the DC brushless motor 220 is simply referred to as a motor.

  After starting the motor drive, in step S501, the ACC / DEC module 205 controlled by the CPU 201 compares the FG (rotation detection) signal (frequency) from the motor with the target frequency corresponding to the target speed.

  When the FG signal is equal to or lower than the target frequency, that is, when the motor speed is high, the process proceeds to step S502, and the ACC / DEC module 205 outputs a DEC signal to the motor to decelerate.

  If the FG signal exceeds the target frequency in step S501, that is, if the motor speed is low, the process proceeds to step S503, and the ACC / DEC module 205 compares the pulse width W of the ACC signal with a predetermined pulse width W0. To do.

  If the pulse width W of the ACC signal is equal to or smaller than the predetermined pulse width W0, the ACC / DEC module 205 sets N = 0 in step S504, proceeds to step S505, and outputs the ACC signal.

  In step S503, if the pulse width W of the ACC signal exceeds the predetermined pulse width W0, the ACC / DEC module 205 sets N = N + 1 in step S506.

  If N is not equal to the predetermined number N0 in step S507, the process proceeds to step S505, and the ACC / DEC module 205 outputs an ACC signal. If N = N0, the process proceeds to step S508, and the motor control IC 301 Stop the motor or shift to the low speed mode without stopping the motor. In the low speed mode, the motor is controlled to rotate at a constant speed at a speed lower than the target speed.

  Here, step S501 functions as a first comparison unit that compares the frequency of the rotation detection signal proportional to the rotation speed of the motor with the target frequency for rotating the motor at a predetermined speed.

  In step S503, when the first comparison means determines that the frequency of the rotation detection signal exceeds the target frequency, the pulse width of the acceleration signal output for accelerating the motor and a predetermined pulse It functions as a second comparison means for comparing the width.

  In step S508, when the second comparison means determines that the pulse width of the acceleration signal exceeds the predetermined pulse width, the motor is stopped or the DC brushless motor is shifted to the low speed mode. It functions as a control means.

  Further, in the present embodiment, when the state in which the pulse width of the acceleration signal is determined to exceed the predetermined pulse width by the second comparison unit continues for a predetermined number of times, the control unit rotates the motor. Is stopped or the motor is shifted to the low speed mode.

  In the first embodiment shown in FIG. 5, the pulse width of the ACC signal is detected, and the motor is decelerated or stopped when the pulse width of a certain value or more continues for a predetermined number of times.

  In the second embodiment, the ACC signal is not output by limiting the pulse width of the ACC signal.

  FIG. 6 is a flowchart showing the procedure of the second embodiment of the DC brushless motor control process executed by the controller unit of FIG. 2 and the control block of the DC brushless motor of FIG.

  Hereinafter, the DC brushless motor 220 is simply referred to as a motor.

  After starting the motor drive, in step S601, the ACC / DEC module 205 controlled by the CPU 201 compares the FG signal (frequency) from the motor with the target frequency corresponding to the target speed.

  When the FG signal is equal to or lower than the target frequency, that is, when the motor speed is high, the process proceeds to step S602, where the ACC / DEC module 205 outputs the DEC signal to the motor to decelerate.

  If the FG signal exceeds the target frequency in step S601, that is, if the motor speed is low, the process proceeds to step S603.

  If the pulse width W of the ACC signal calculated by the ACC / DEC module 205 is equal to or smaller than the predetermined pulse width W1 in step S603, the process proceeds to step S605, and the ACC / DEC module 205 outputs the ACC signal.

  In step S603, if the pulse width W of the ACC signal calculated by the ACC / DEC module 205 exceeds the predetermined pulse width W1, the ACC / DEC module 205 sets W = W1 in step S604. In step S606, the ACC / DEC module 205 outputs an ACC signal.

  Here, step S601 functions as a first comparison unit that compares the frequency of the rotation detection signal proportional to the rotation speed of the motor with the target frequency for rotating the motor at a predetermined speed.

  In step S603, when the first comparison means determines that the frequency of the rotation detection signal exceeds the target frequency, the pulse width of the acceleration signal output for accelerating the motor and a predetermined pulse width Functions as a second comparison means.

  Step S604 functions as a limiting unit that limits the pulse width of the acceleration signal to the predetermined pulse width when the second comparison unit determines that the pulse width of the acceleration signal exceeds the predetermined pulse width. To do.

  As described above, the motor and the mechanical mechanism to be driven can be protected by detecting the overload state of the DC brushless motor.

  When the same motor is used in a plurality of locations in the apparatus, the load is different at each location. By setting an overload limit value according to the location, it is possible to reduce the cost by using a low-strength gear at a light load.

  The object of the present invention can also be achieved by executing the following processing. That is, a storage medium storing software program codes for realizing the functions of the above-described embodiments is supplied to a system or apparatus, and a computer (or CPU, MPU, etc.) of the system or apparatus is stored in the storage medium. This is a process of reading the program code.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the program code and the storage medium storing the program code constitute the present invention.

  Moreover, the following can be used as a storage medium for supplying the program code. For example, floppy (registered trademark) disk, hard disk, magneto-optical disk, CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD + RW, magnetic tape, nonvolatile memory card, ROM or the like. Alternatively, the program code may be downloaded via a network.

  Further, the present invention includes a case where the function of the above embodiment is realized by executing the program code read by the computer. In addition, an OS (operating system) running on the computer performs part or all of the actual processing based on the instruction of the program code, and the functions of the above-described embodiments are realized by the processing. Cases are also included.

  Furthermore, the present invention includes a case where the functions of the above-described embodiment are realized by the following processing. That is, the program code read from the storage medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. Thereafter, based on the instruction of the program code, the CPU or the like provided in the function expansion board or function expansion unit performs part or all of the actual processing.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram of a controller unit in the image forming apparatus of FIG. 1. FIG. 3 is a control block diagram of the DC brushless motor in FIG. 2. It is a timing chart of speed control of the DC brushless motor in FIG. 4 is a flowchart showing a procedure of a first embodiment of a DC brushless motor control process executed by a controller unit of FIG. 2 and a control block of the DC brushless motor of FIG. 3. It is a flowchart which shows the procedure of 2nd Embodiment of the control process of the DC brushless motor performed by the control part of the controller part of FIG. 2, and the control block of the DC brushless motor of FIG.

Explanation of symbols

200 Controller 201 CPU
203 ROM
204 RAM
205 ACC / DEC module 220 DC brushless motor 301 Motor control IC
325 FG pattern

Claims (11)

In a motor control device for controlling a DC brushless motor,
Comparing means for comparing a pulse width of an acceleration signal output for accelerating the DC brushless motor with a predetermined pulse width;
Control means for stopping the rotation of the DC brushless motor when the comparison means determines that the pulse width of the acceleration signal exceeds the predetermined pulse width;
A motor control device comprising:   The control means stops the rotation of the DC brushless motor when the comparison means determines that the pulse width of the acceleration signal exceeds the predetermined pulse width for a predetermined number of times or more. The motor control device according to claim 1. In a motor control device for controlling a DC brushless motor,
Comparing means for comparing a pulse width of an acceleration signal output for accelerating the DC brushless motor with a predetermined pulse width;
Control means for causing the DC brushless motor to shift to a low speed mode when the comparison means determines that the pulse width of the acceleration signal exceeds the predetermined pulse width;
A motor control device comprising:   When the state in which the pulse width of the acceleration signal is determined to exceed the predetermined pulse width by the comparing means continues for a predetermined number of times, the control means shifts the DC brushless motor to the low speed mode. The motor control device according to claim 3. In a motor control device for controlling a DC brushless motor,
First comparison means for comparing a frequency of a rotation detection signal proportional to a rotation speed of the DC brushless motor and a target frequency for rotating the DC brushless motor at a predetermined speed;
When the first comparison means determines that the frequency of the rotation detection signal exceeds the target frequency, a pulse width of an acceleration signal output for accelerating the DC brushless motor and a predetermined pulse width are obtained. A second comparison means for comparing;
Control means for stopping the rotation of the DC brushless motor when the second comparison means determines that the pulse width of the acceleration signal exceeds the predetermined pulse width;
A motor control device comprising:   When the state in which the pulse width of the acceleration signal is determined to exceed the predetermined pulse width by the second comparing means continues for a predetermined number of times, the control means stops the rotation of the DC brushless motor. The motor control device according to claim 5. In a motor control device for controlling a DC brushless motor,
First comparison means for comparing a frequency of a rotation detection signal proportional to a rotation speed of the DC brushless motor and a target frequency for rotating the DC brushless motor at a predetermined speed;
When the first comparison means determines that the frequency of the rotation detection signal exceeds the target frequency, a pulse width of an acceleration signal output for accelerating the DC brushless motor and a predetermined pulse width are obtained. A second comparison means for comparing;
Control means for causing the DC brushless motor to shift to a low speed mode when the second comparison means determines that the pulse width of the acceleration signal exceeds the predetermined pulse width;
A motor control device comprising:   When the state in which the pulse width of the acceleration signal is determined to exceed the predetermined pulse width by the second comparison unit continues for a predetermined number of times, the control unit shifts the DC brushless motor to the low speed mode. The motor control apparatus according to claim 7. In a motor control device for controlling a DC brushless motor,
Comparing means for comparing a pulse width of an acceleration signal output for accelerating the DC brushless motor with a predetermined pulse width;
Limiting means for limiting the pulse width of the acceleration signal to the predetermined pulse width when the comparison means determines that the pulse width of the acceleration signal exceeds the predetermined pulse width;
A motor control device comprising: In a motor control device for controlling a DC brushless motor,
First comparison means for comparing a frequency of a rotation detection signal proportional to a rotation speed of the DC brushless motor and a target frequency for rotating the DC brushless motor at a predetermined speed;
When the first comparison means determines that the frequency of the rotation detection signal exceeds the target frequency, a pulse width of an acceleration signal output for accelerating the DC brushless motor and a predetermined pulse width are obtained. A second comparison means for comparing;
Limiting means for limiting the pulse width of the acceleration signal to the predetermined pulse width when the second comparing means determines that the pulse width of the acceleration signal exceeds the predetermined pulse width;
A motor control device comprising:   An image forming apparatus comprising the motor control device according to claim 1.

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