JP2011019324A - Motor control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor control device capable of reliably setting a set value before rotating a motor and properly control the motor.SOLUTION: A central control IC 100 carries out serial communication with a decentralized control IC 110. After transmitting a motor rotation direction signal CW/CCW and a current setting signal I1, I0 to the decentralized control IC 110, it waits for a predetermined time WAIT. After the predetermined time WAIT has passed, the central control IC 100 outputs a clock for rotating a stepping motor to a motor driver 200.

Description

  The present invention relates to a motor control device that controls a motor.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic apparatus, a stepping motor is used to facilitate control of a sheet conveyance amount when conveying a sheet on which an image is printed. When a stepping motor is used, the paper feed amount can be easily managed by the number of pulses sent to the stepping motor. In addition, since the stepping motor can be controlled in an open loop, easy control is also a main reason for using the stepping motor.

  In order to drive a stepping motor, recently, a dedicated IC (hereinafter referred to as a motor driver) is used instead of configuring a drive circuit by connecting transistors and diodes one by one.

  The motor driver mainly receives a clock signal for determining the rotation speed of the motor, a current setting signal for changing the maximum value of the current flowing through the stator of the motor in multiple steps, and a motor rotation direction signal for determining the rotation direction of the motor.

  The clock signal input method is roughly classified into a method of inputting the number of independent stator windings in the motor and a method of inputting only one speed signal. From the viewpoint of reducing the number of harnesses, a method of inputting only one speed signal has recently been adopted.

  As for the signal for determining the current flowing through the stator, conventionally, a single-line binary switching method has been often controlled. However, in order to perform finer control, another line is prepared. More and more four-value control is performed. Moreover, since there are only two directions for the rotation direction, there is only one control line.

  These signals can be broadly divided into two types: a clock-like signal that determines the rotation speed and a signal related to a set value for rotation.

  Conventionally, when starting to rotate a motor, a setting value for rotating the motor is set in the motor driver, and at the same time, a clock-like signal for determining the rotation speed is input to the motor driver (for example, Patent Document 1). See the conventional example).

  FIG. 8 is a diagram showing a configuration of a conventional motor control device. In this motor control apparatus, a motor driver 200a is directly connected to the central control IC 100a. Motor rotation direction signal CW / CCW, current setting signals I1 and I0, and motor rotation signal CLK are transmitted from central control IC 100a to motor driver 200a.

  FIG. 9 is a timing chart showing changes in signals when the motor is controlled by the conventional motor control method. In this motor control system, a system in which the motor rotation direction signal, the current setting signal, and the motor rotation signal (clock) are changed all at once is adopted. In this case, when outputting a set value signal for rotating the motor and a clock signal for determining the rotation speed, there was almost no problem in the output timing.

  On the other hand, in recent image forming apparatuses, the number of motors has increased with the addition of functions. The main stepping motors are provided as they are, and conventionally, binary control of ON / OFF by solenoids, for example, dust-proof lids of laser scanners, for example, to prevent beating noise and large impacts (shock) In view of the above, stepping motors have been introduced.

  These stepper motors are located far away from the central controller for fine control. In the case of adopting the same configuration as the conventional one, the distance from the motor driver to the stepping motor is extended, or the distance from the central controller to the motor driver is extended.

  In the former case, the amount of harness from the motor driver to the stepping motor increases, which is not preferable. On the other hand, in the latter case, a harness that transmits a clock signal having a high frequency is drawn long, which is not preferable from the viewpoint of signal noise.

  On the other hand, it has been proposed that the controllers are distributed, and the central controller (central control IC) and the controllers (distributed control IC) arranged in a distributed manner communicate with each other for control. In this case, as a communication control method, a serial communication method in which data is arranged in time series is often used in order to reduce the number of harnesses to the maximum. If the clock frequency signal that determines the rotation speed of the motor and the setting value signal for rotating the motor are loaded simultaneously in serial communication, a higher frequency than the higher one of these signals must be used. This is not preferable from the viewpoint of signal noise.

  On the other hand, the clock frequency signal (motor rotation signal) for rotating the motor and the set value signal for rotating the motor are separated, and only the set value signal for rotating the motor is transmitted via serial communication. A control method was proposed.

  FIG. 10 is a diagram showing a configuration of a motor control device in which a motor rotation signal CLK and a set value signal for rotating the motor are separated. Between the central control IC 100a and the distributed control IC 110a, a signal line 85a for a motor rotation signal CLK and a signal line 81a for a set value signal for rotating the motor by serial communication are connected. Further, between the distributed control IC 110a and the motor driver 200a, a motor rotation direction signal CW / CCW and current setting signals I0 and I1 are transmitted as setting value signals for rotating the motor. The distributed control IC 110a and the motor driver 200a, and the motor driver 200a and the stepping motor 350a are connected by four signal lines, respectively.

Japanese Patent Laid-Open No. 11-84790

  However, the conventional motor control device has the following problems. As described above, in the case of a motor control device in which a distributed control IC is interposed between the central control IC and the motor driver and serial communication is performed between the central control IC and the distributed control IC, the central control IC is It took time for the distributed control IC to output after issuing the command. Therefore, after the central control IC outputs a clock for determining the rotation speed of the motor, a setting value for rotating the motor may be output from the distributed control IC, and desired motor control can be performed. There wasn't.

  FIG. 11 is a timing chart showing changes in signals when a motor is controlled in a motor control device in which a distributed control IC is interposed. Serial communication of the motor rotation direction signal CW / CCW and the motor current setting signals I0a and I1a is performed from the central control IC to the distributed control IC (period m in the figure), and the result of the communication is reflected and the signal is reflected. The motor rotation signal CLK is output before the change of. As described above, since the rotation direction and current of the motor change when the motor starts to rotate, the motor has not been smoothly rotated.

  Therefore, an object of the present invention is to provide a motor control device that can reliably set a set value before rotating the motor and can control the motor appropriately.

  In order to achieve the above object, a motor control device according to the present invention controls motor driving means for rotating the motor in accordance with an input pulse signal according to a set value for rotating the motor, and the motor driving means. And a control unit that transmits the set value and sets the transmitted set value to the motor drive unit, and after transmitting the set value. And a waiting means for waiting for a predetermined time, and an output means for outputting the pulse signal to the motor driving means after waiting for the predetermined time.

  The motor control device according to claim 1 of the present invention waits for a predetermined time after transmitting the set value set in the motor driving means, and after this standby, outputs a pulse signal to the motor driving means. Thereby, before outputting a pulse signal to a motor drive means and rotating a motor, a setting value can be reliably set to a motor drive means, and rotation of a motor can be controlled appropriately. In this way, it is possible to eliminate the time lag of the set value when the motor rotates.

  The motor control device according to claim 2 sets the changed set value in synchronization with the pulse signal when the rotation speed is switched during the rotation of the motor. Thereby, it is possible to prevent a change in setting values such as a current value flowing in the motor and a rotation direction before the rotation speed changes. Therefore, it can be avoided that the motor is out of synchronization and becomes uncontrollable.

  According to the motor control device of the third, fourth, and fifth aspects, the rotation of the motor can be appropriately controlled even when a large number of second control means connected to the first control means by serial communication overlap. it can. In addition, the amount of harness can be reduced.

  According to the motor control device of the sixth aspect, it is possible to reliably set the set value in the motor driving means.

  According to the motor control device of the seventh aspect, it is possible to reliably set the rotation direction of the motor necessary for the rotation of the motor and the value of the current flowing through the motor.

It is sectional drawing which shows the structure of the image forming apparatus to which the motor control apparatus of 1st Embodiment was applied. It is a figure which shows the structure of a motor control apparatus. It is a flowchart which shows the motor control procedure performed by central control IC100. It is a timing chart which shows the change of the signal in each part of a motor control device. It is a figure which shows the structure of the motor control apparatus in 2nd Embodiment. 3 is a diagram showing a configuration of a D-flip flop (FF) 300. FIG. It is a timing chart which shows change of a signal of each part of a motor control device. It is a figure which shows the structure of the conventional motor control apparatus. It is a timing chart which shows the change of the signal at the time of controlling a motor by the conventional motor control system. It is a figure which shows the structure of the motor control apparatus which divided | segmented the motor rotation signal CLK and the signal of the setting value for rotating a motor. 5 is a timing chart showing changes in signals when controlling a motor in a motor control device in which a distributed control IC is interposed.

  An embodiment of a motor control device of the present invention will be described with reference to the drawings. The motor control device of this embodiment is applied to an image forming apparatus that forms a color image.

[First Embodiment]
FIG. 1 is a cross-sectional view illustrating a configuration of an image forming apparatus to which the motor control device of the first embodiment is applied. In this image forming apparatus, one sheet of paper P to be printed mounted in the cassette 17 is taken out by the pickup roller 15 and conveyed to the upper part in the drawing by a roller pair 19 driven by a stepping motor.

  When the toner image formed on the intermediate transfer belt 8 at the position of the roller 12 is transferred to the paper P, the paper P is further conveyed upward. When the toner image is pressure-fixed on the paper P by the fixing roller pair 16, the paper P is discharged out of the apparatus by the paper discharge roller pair 21.

  On the other hand, an electrostatic latent image is formed on the photoreceptor 2 charged by the charger 3 in accordance with the image formed by the laser 7. Here, the yellow (Y), magenta (M), cyan (C), and black (Bk) photoreceptors 2a, 2b, 2c, and 2d are collectively referred to as the photoreceptor 2 when it is not necessary to distinguish them. The same applies to the charging device 3, the developing device 4, and the primary transfer device 5.

  The electrostatic latent image formed on the photoreceptor 2 is converted into a toner image by the developing device 4. Further, the toner image is transferred onto the intermediate transfer belt 8 by the primary transfer unit 5. As the charging device 3, the photoconductor 2 and the developing device 4 rotate, the toner image formed on the photoconductor 2 is continuously transferred to the intermediate transfer belt 8. At this time, the intermediate transfer belt 8 is rotationally driven by the rollers 10 and 11.

  The rotating members such as the various roller pairs, the charger 3, the photosensitive member 2, the developing device 4, and the intermediate transfer belt 8 are driven by a motor. Here, a motor type such as a DC motor, a DC brushless motor, or a stepping motor is selected based on the characteristics of each rotating member.

  The motor driver for driving the stepping motor determines the motor rotation direction signal CW / CCW that determines the rotation direction of the motor, the current setting signals I0 and I1 that switch the current value that flows through the motor winding in four stages, and the rotation speed of the motor. A motor rotation signal (clock (pulse signal)) CLK is input. And a motor driver (motor drive means) performs the output which excites the coil | winding of a motor according to these inputs. For example, when a winding of a two-phase stepping motor (hereinafter also simply referred to as a motor) is excited in a floating state, four outputs (= 2 phases × 2) are output. Needless to say, the motor driver is not limited to such a two-phase / floating load. As a result, the motor rotates in the set direction at a speed corresponding to the clock.

  FIG. 2 is a diagram showing the configuration of the motor control device. In this motor control apparatus, a distributed control IC 110 is placed between a central control IC 100 and a motor driver (MOTOR DRIVER) 200. The central control IC 100 (first control means) and the distributed control IC 110 (second control means) perform serial communication.

  General synchronous serial communication is performed with a total of three transmission data (TxD) lines, reception data (RxD) lines, and a clock (SCLK: synchronous clock) line for transmitting them. In the asynchronous method and other methods, the number of connection lines can be reduced to two or less, but this embodiment shows a case of three. Further, the connection of the distributed control IC, the motor driver, and the stepping motor is the same as the conventional connection shown in FIG. A plurality of motor drivers are connected to the distributed control IC.

  Here, the number of harnesses from the central control IC to the motor driver is compared. First, as shown in FIG. 8, when the motor driver is arranged near the motor in the conventional configuration in which the motor driver is directly connected to the central control IC, in order to drive four motors, Four are required. Since four motor drivers each require four inputs, a total of 16 harnesses are required.

  On the other hand, when the motor driver is arranged in the vicinity of the central control IC, in order to drive four motors, four harnesses for supplying current to each motor are required, so a total of 16 harnesses are required. In any case, in the case of a configuration similar to that of the conventional FIG. 8, 16 harnesses are required.

  Next, in the configuration shown in FIG. 2, when a motor driver and a distributed control IC are placed near the motor, a total of four harnesses are required between the central control IC and the distributed control IC. That is, a total of four harnesses are required, that is, three serial communication harnesses for setting a set value in the motor driver and one clock harness for rotating the motor. In FIG. 2, the clock (CLK) harness for rotating the motor is directly connected to the motor driver from the central control IC in order to distinguish from the synchronous clock (SCLK) harness. Actually, a distributed control IC is interposed.

  As described above, three harnesses for serial communication are common in synchronous communication. Note that the number of control lines can be reduced to two or one by using asynchronous communication or the like. In this way, the amount of harness can be reduced by distributing the control ICs and arranging them with the motor driver near (near) the motor.

  Next, a method for transmitting the setting value of the motor driver by serial communication will be described. In serial communication, an address for setting a rotation direction signal and a current control signal and its data are placed on a data line, transmitted from the central control IC 100 to the distributed control IC 110, and data is written.

  When receiving the address and data, the distributed control IC 110 reflects the received data value on the motor driver 200 of the received address. Thus, the distributed control IC 110 receives and reflects all data.

  In the conventional method, data is reflected immediately in one clock. However, in serial communication, since data is rearranged in time series, it takes time to communicate compared to the conventional method. As a result, it took time for the setting values to be reflected in the motor driver.

  As shown in FIG. 11, when the central control IC performs serial communication and outputs a clock for rotating the motor, the clock output timing is earlier than the set value of the motor. As a result, the motor starts to rotate without reflecting the set value of the motor.

  Therefore, the motor control device of this embodiment waits for a predetermined time after the central control IC performs serial communication with the distributed control IC, and thereafter (after waiting for the predetermined time), a clock for rotating the motor. Is output.

  FIG. 3 is a flowchart showing a motor control procedure executed by the central control IC 100. FIG. 4 is a timing chart showing changes in signals in each part of the motor control device. First, the central control IC 100 sets the set value of the motor in the distributed control IC 110 by serial communication as in the prior art (step S1, period a in FIG. 4).

  After starting serial communication, the central control IC 100 waits for a predetermined time WAIT or longer (step S2, period b in FIG. 4). Here, the central control IC 100 investigates in advance how long the motor setting value is reflected in the motor driver 200 after serial communication is started, that is, after the motor setting value is transmitted. deep. Then, as a result of the investigation, the central control IC 100 stores the time until the motor set value is reflected as a predetermined time WAIT in the storage medium.

  When the predetermined time WAIT elapses, the central control IC 100 outputs a clock (motor rotation signal D1) for rotating the motor (step S3). Thereafter, the central control IC 100 ends this control.

  Thus, after the motor rotation direction signal CW / CCW and the current setting signals I1 and I0 are set in the motor driver 200 as the motor setting values, the clock (motor rotation signal D1) is sent from the central control IC 100 to the motor driver 200. Entered. Therefore, the central control IC 100 can start rotation after reflecting the set value of the motor in the motor driver 200.

  According to the motor control apparatus of the first embodiment, the central control IC 100 transmits a set value of the motor to the distributed control IC 110 by serial communication, waits for a predetermined time WAIT, and then a clock (pulse signal) for rotating the motor. ) Is output. Thereby, the time gap of the set value when the motor rotates can be eliminated. Therefore, even when a large number of distributed control ICs 110 connected to the central control IC 100 are overlapped, the motor can be reliably rotated and the stepping motor can be appropriately controlled.

  Although the case where both the rotation direction of the motor and the current value energized to the motor are set as the motor setting value in the motor driver, the same control is performed even when either one is set. Is called. In this case, motor setting values other than those set by serial communication are registered as fixed values in the motor driver.

[Second Embodiment]
In the first embodiment, the motor control at the start of the rotation of the motor is shown. In the second embodiment, motor control in the case where the rotation speed is switched by changing the set value of the motor and the cycle of the clock (pulse signal) during the rotation of the motor is shown.

  When switching the rotation speed during motor rotation, if the same motor control as before is performed, the current and rotation direction will change before the rotation speed changes, and the desired control will not be possible, and the motor will be synchronized. This may cause loss of control.

  For this reason, it is necessary to change the setting value of the motor driver and the clock at the same time, and the second embodiment shows such motor control.

  FIG. 5 is a diagram illustrating a configuration of a motor control device according to the second embodiment. The same components as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted. In the motor control apparatus of the second embodiment, a D-flip flop (FF) 300 (holding unit) is provided between the distributed control IC 110 and the motor driver 200.

  FIG. 6 is a diagram showing a configuration of the D-flip flop (FF) 300. The D-flip flop (FF) 300 includes three D-FF units 301, 302, and 303 and a clock gate circuit 304. Motor rotation direction signals CW / CCW and current setting signals I0 and I1 are input to the D terminals of the three D-FF sections 301, 302, and 303, respectively, and output according to the clock from the clock gate circuit 304.

  FIG. 7 is a timing chart showing changes in signals at various parts of the motor control device. When a value is set by serial communication from the central control IC 100 to the distributed control IC 110 (period e in FIG. 7), the distributed control IC 110 outputs the value. However, since the clock gate circuit 304 is not opened by the WAIT signal from the distributed control IC 110, the D-FF 300 keeps the previous value without changing.

  Once the WAIT signal is released, that is, when the WAIT signal in FIG. 7 changes from H to L, the clock gate circuit 304 is opened, and then at the rising point of the motor clock that comes first (timing A in FIG. 7). The D-FF 300 outputs a motor set value. Then, the motor setting values (rotation direction signal and current setting signal) change in synchronization with the motor clock.

  The timing at which the WAIT signal is released can be set by the distributed control IC 110 performing serial communication with the central control IC 100. Alternatively, the value investigated in advance is stored in the storage medium of the distributed control IC 110. As described above, the time from when the serial communication (period e) in FIG. 7 is started until the WAIT signal is canceled and the first clock CLK after the change rises is equal to the predetermined time WAIT of the first embodiment. It will be equivalent.

  According to the motor control device of the second embodiment, when the rotation speed is switched during the rotation of the motor, the current value flowing through the motor and the rotation direction of the motor are prevented from changing before the rotation speed changes. be able to. Therefore, desired control can be performed, and it can be avoided that the motor is out of synchronization and becomes uncontrollable.

  The present invention is not limited to the configuration of the above-described embodiment, and any configuration can be used as long as the functions shown in the claims or the functions of the configuration of the present embodiment can be achieved. Is also applicable.

  For example, the motor control device of the present invention is applicable not only to an image forming apparatus but also to various electronic devices.

100 Central control IC
110 Distributed control IC
200 Motor Driver 300 D-Flip-Flop 304 Clock Gate Circuit

Claims (7)

A motor control device comprising: motor driving means for rotating the motor according to an input pulse signal according to a set value for rotating the motor; and control means for controlling the motor driving means.
The control means includes
Setting means for transmitting the setting value and setting the transmitted setting value to the motor driving means;
Waiting means for waiting for a predetermined time after transmitting the set value;
A motor control device comprising: output means for outputting the pulse signal to the motor driving means after waiting for the predetermined time.   When the setting means changes the setting value and the period of the pulse signal to change the rotation speed during the rotation of the motor, the setting means transmits the changed setting value and then holds the changed setting value. A holding means is provided, and the set value after change held by the holding means is set in the motor driving means in synchronization with the first pulse signal after change of the cycle of the pulse signal. The motor control device according to 1.   The control means is connected to the first control means for transmitting the set value by serial communication with the first control means, and the second control means for setting the received set value to the motor driving means. The motor control device according to claim 1, further comprising:   4. The motor control apparatus according to claim 3, wherein the second control unit and the motor driving unit are arranged in the vicinity of the motor.   The motor control apparatus according to claim 4, wherein a plurality of the motor drive units are connected to the second control unit.   The motor control device according to claim 1, wherein the predetermined time is a time from when the set value is transmitted by the setting unit to when the set value is reflected on the motor driving unit.   The motor control device according to claim 1, wherein the set value includes at least one of a rotation direction of the motor and a current value flowing through the motor.