JP2010193648A - Controller for driving dc brushless motor and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller for driving a DC brushless motor that stops rotation of a motor with a small regenerative current and in a short time, and to provide an image forming device equipped with this drive controller. <P>SOLUTION: In the controller for driving the DC brushless motor, by which a rotation speed is controlled in accordance with a clock signal indicating the rotation speed, a control means is provided which controls so that, in stopping the rotation of the DC brushless motor, the clock signal is stopped first (S3) to wait until the rotation speed of the DC brushless motor is reduced to a predetermined rotation speed (S6), and short brake is started (S7) when the rotation speed of the DC brushless motor reaches the predetermined rotation speed to stop the rotation. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to not only an image forming apparatus such as a copying machine, a multifunction machine, a laser printer, and a facsimile machine, but also to a device equipped with a DC brushless motor, and more particularly to suppression of a regenerative current generated when rotation of the DC brushless motor is stopped. Is.

  Conventionally, there is a short brake as a control for stopping the rotation of a DC brushless motor in a short time (see, for example, Patent Document 1). FIG. 11 shows the falling phase current value 403 and the change in the rotation speed 404 of the motor when the short-brake operation of the DC brushless motor is performed. As shown in FIG. 11, when the short brake operation is performed while the DC brushless motor is rotating, the phase current value 403 exceeds the current limit value 402 of the motor driver at 401. Conventionally, it has been necessary to provide a motor driver having a rating capable of withstanding this regenerative current and having a thermal loss resistance according to the rating so as not to cause this.

JP 2006-39197 A

  However, a motor driver that can withstand such a regenerative current is more expensive than a motor driver that can withstand the current required to rotationally drive the DC brushless motor.

  The present invention has been made under such circumstances, and a DC brushless motor drive control device capable of stopping the rotation of the motor in a short time with a small regenerative current and an image provided with the drive control device. It is an object of the present invention to provide a forming apparatus.

  In order to solve the above problems, in the present invention, the DC brushless motor drive control device is configured as described in the following (1) and (2), and the image forming device is configured as described in the following (3).

(1) A DC brushless motor drive control device in which the rotation speed is controlled in accordance with a clock signal instructing the rotation speed,
When the rotation of the DC brushless motor is stopped, first, the clock signal is stopped, waiting for the rotation speed of the DC brushless motor to decrease to a predetermined rotation speed, and short-circuiting when the predetermined rotation speed is reached. A DC brushless motor drive control device comprising control means for controlling to start braking and stop rotation.

(2) A DC brushless motor drive control device in which the rotation speed is controlled according to a clock signal instructing the rotation speed,
When the rotation of the DC brushless motor is stopped, first, the clock signal is stopped and the DC brushless motor waits for the rotation speed of the DC brushless motor to drop to a predetermined first rotation speed, and then the predetermined first rotation speed. When reverse rotation brake is reached, the reverse rotation brake is started to wait for the rotational speed of the DC brushless motor to fall to the predetermined second rotational speed, and short brake is started when the predetermined second rotational speed is reached. And a DC brushless motor drive control device comprising control means for controlling the rotation to stop.

  (3) An image forming apparatus comprising the DC brushless motor drive control device according to (1) or (2).

  According to the present invention, the rotation of the motor can be stopped in a short time with a small regenerative current.

The flowchart which shows the motor stop operation | movement in Example 1. FIG. Block diagram showing the configuration of the first embodiment The figure which shows transition of the motor rotational speed and phase current in Example 1. Detailed view of the DRIVER section of FIG. Detailed view of output controller Output controller sequence diagram Diagram showing changes in motor rotation speed and phase current The figure which shows transition of the motor rotational speed and phase current in the deformation | transformation of Example 1. FIG. The flowchart which shows the motor stop operation | movement in the deformation | transformation of Example 1. FIG. Sectional drawing which shows the structure of Example 2 The figure which shows transition of motor rotation speed and phase current at the time of the short brake in the conventional example

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to embodiments of a DC brushless motor drive control device and an image forming apparatus.

The “DC brushless motor drive control device” according to the first embodiment will be described. FIG. 2 is a block diagram showing the configuration of the DC brushless motor drive control device of this embodiment, and FIG. 3 is a diagram showing the behavior of this embodiment device. The present embodiment will be described in detail with reference to FIGS.
FIG. 3 shows the behavior of the DC brushless motor drive control device of this embodiment as a single voltage by stopping the change in the voltage level of the clock signal 212 in the clock generator 104 of FIG. 2 in this embodiment. The time vs. motor rotation speed 412 is plotted. At the same time, as a comparative example, the time when the short brake is applied after being lowered to the motor rotation speed by supplying the clock signal 212 corresponding to the target rotation speed-the motor rotation speed 406 is plotted, and the difference in phase current is plotted. Is also plotted.

In the case of the comparative example, the short brake is applied after the motor rotation speed is controlled to the target rotation speed 408. Thus, the regenerative current can be reduced, but it is necessary to take into account variations in individual motors from when the clock signal 212 corresponding to the target rotational speed is started until the target rotational speed is reached. For this reason, it is necessary to increase the time margin from when the clock signal 212 corresponding to the target rotation speed is started until the short brake is applied, and as a result, the time for stopping the rotation of the motor is increased by the period 407.
In this embodiment, when the rotation of the motor is stopped, first, the clock signal 212 is stopped to reduce the rotation speed of the motor. Then, in response to the detection result of the motor rotation speed detection unit 101 becoming the target rotation speed 408, a short brake is started to stop the rotation of the motor. As a result, the regenerative current can be reduced and the rotation of the motor can be stopped in a short time.

  Reference numeral 530 in FIG. 2 represents a signal for the clock generation unit 104 to stop the clock from the CPU 200. Reference numeral 501 represents a signal for starting a short brake from the CPU 200.

  FIG. 4 shows the inside of the driver unit 224. The preset output of the current limit control unit 377 and the output of the PWM control unit 378 are compared by the comparator unit 372. At this time, the output signal 371 from the comparator unit 372 is influenced by the PWM control unit 378. Causes the operation of the output lines WH125, VH124, UH123, WL126, VL127, and UL128 to the motor winding of the PRI DRIVER unit 358, which may cause a regenerative current to flow to the motor.

  For this reason, it is detected that the clock signal 212 has stopped, and an output suppression unit 380 is provided to deal with the output lines WH125, VH124, UH123, WL126, VL127, and UL128.

  A detailed circuit example of the output suppression unit 380 of FIG. 4 is shown in FIG. 5, and its operation sequence is shown in FIG. In FIG. 5, the clock signal 212 output from the clock generation unit 104 in FIG. 2 is coupled by the capacitor 418 and input to the integration circuit unit 420. Since the output signal 429 of the integrating circuit unit 420 integrates the edge portion of the clock signal 212 unit, the waveform is as shown by 429 in FIG. 6 until the clock signal is stopped at the time point 438 in FIG. Further, the signal is inputted to the resistor 424 and the differentiating circuit 421, and then inputted to the peak detecting unit 422 through the differentiating circuit output 430.

The buffer output 435 in the peak detector 422 has the waveform 435 in FIG. 6 until the clock signal is stopped at the time 438 in FIG. An output 435 in FIG. 5 is a signal before peak detection, and the charge that is prevented from backflow by the diode 432 moves to the capacitor 433 and is charged up. The voltage waveform of the signal line 425 in FIG. 5 at this time is shown as 425 in FIG. The signal line 425 in FIG. 5 has a discharge resistor 437 connected in parallel with the capacitor 433 described above, and the time constant for discharging the capacitor 433 can be determined by the resistance value of the discharge resistor 437. Assuming that the voltage of the capacitor 433 is 5 V at the time 438 in FIG. 6, the initial voltage V0 of the following formula is substituted for 5.0, the R of the following formula is substituted for the resistance value of the discharge resistor 437, and the following formula C is the capacitor 433 Substitute the capacity value of.
V = V0 × exp (−t / R × C)
Conversely, when V in the above equation is the REF signal 436 of the comparator 434 in FIG. 5, the discharge time T can be obtained by T = R × C / V0−V. If a charge pulse is not obtained on the signal line 425 by the signal input from the clock signal 212 within this discharge time, the voltage of the signal line 425 in FIG. Thus, the output signal 381 of the comparator is inverted. That is, it can be determined that the oscillation of the clock signal 212 has stopped for a predetermined time.

  For example, when the output unit of the comparator 434 is configured as an open collector or open drain type, the output signal 381 of the output suppression unit 380 shown in FIG. 4 can be controlled so as not to be changed by wired-ORing with the output of the comparator unit 372. As a result, it is possible to eliminate the influence of the PWM control unit 378 in FIG. At this time, the output of the comparator unit 372 in FIG. 4 is also an open collector or open drain output so that it does not collide with the output signal 381 of the output suppression unit 380 and become an intermediate potential.

  As described above, during the period from 409 to 411 in FIG. 3, the output of the UH 123, the output of the VH 124, the output of the WH 125, the output of the WL 126, and the output of the WL 126 according to the stop of the oscillation of the clock signal 212 of the clock generation unit 104 of FIG. The outputs of VL127 and UL128 all work in the direction in which TR1 106, TR2 107, TR3 108, TR4 109, TR5 110, and TR6 111 are turned off.

  Almost no current flows through the motor winding U 116, the motor winding V 117, and the motor winding W 118. This is described on the waveform of the phase current 413 in FIG. 3 between 409 and 411 in FIG. Thereafter, in the waveform of the motor rotation speed 406 of the conventional example in which the number of clocks is decreased, the time for the motor rotation speed to converge to the target rotation speed 408 in the period 407 is taken into consideration. However, by setting the clock number to 0 when the clock number 409 is down, the motor rotational speed is reduced below the target rotational speed at the time of the short brake timing 405 as indicated by 412 in FIG. In general, the regenerative current at the time of the short brake timing 405 is relatively small as indicated by 413, and the motor stop time is shortened as compared with the conventional motor, such as the motor rotation speed 412.

  Referring to FIG. 7, the motor rotation speeds 406 and 412 and the phase current 413 when the oscillation signal of the clock signal 212 output from the clock generation unit 104 in FIG. It is the same as the description. The motor rotation speed detection unit 101 in FIG. 2 includes an FG pattern and its peripheral circuits. Then, when it is detected that the rotational speed of the motor has reached the target rotational speed 408 of FIG. 7, the output control signal 100 of the motor rotational speed detector 101 of FIG. 2 is applied to the clock signal output line 129 of the clock generator 104. Instructs to output clock signal. As a result, the output signal 381 of the output suppression unit 380 can be canceled for short brake control. By applying the short brake at the target rotational speed 408, it is possible to apply the short brake at a timing 415 that is earlier than the short brake timing 405 described in FIG. For this reason, it becomes possible to reduce the stop time of a motor more.

  However, the target rotation speed 408 in FIG. 7 is determined in advance as the peak value 414 in FIG. 7 so as not to exceed the current limit value 402 of the phase current during the short brake.

FIG. 8 is a diagram showing a modification operation of this embodiment. As shown in the drawing, at the time 442 when the motor rotation speed reaches a predetermined first rotation speed 440, the reverse rotation brake is applied to reverse the driving direction of the UVW motor winding and increase the braking force further than the short brake. The motor rotation speed-time transition 445 at the time was plotted. By applying the short brake at the timing 443 at which the second rotation speed 441 in FIG. 8 is reached, the motor stop time is further shortened than the motor rotation speed transition 416 shown in FIG. The transition of the phase current at that time is 444 in FIG. The above-described phase current is the same in any of the U-phase, V-phase, and W-phase motor windings 116, 117, and 118.
As the above-described transistors 106 to 111, bipolar, CMOS, FET, or the like can be used.

In the present embodiment, the description has been given with the three-phase brushless motor described as the DC brushless motor, but the same control can be performed with a DC brushless motor other than the three-phase brushless motor.
In the short brake, the upper transistors 106, 108, 110 connected to the motor power supply 105 in FIG. 2 are turned off, and the lower transistors 107, 109, 111 connected to GND are turned on. A braking operation is performed by causing the lower transistors 107, 109, and 111 to generate / consume a regenerative current.

  A configuration example of a short brake circuit in the PRI DRIVER unit 358 is described in the lower part of FIG. Control logics 510 to 515 are provided for the signals 502, 503, 504, 505, 506, and 507 for driving the WH 125, VH 124, UH 123, WL 126, VL 127, and UL 128. When the short brake signal 501 becomes the HI level, the S input of the control logic 510 to 512 is set by the NOT gate 508, the output lines WH125, VH124 and UH123 all output HI, and the R inputs 513 to 515 are reset. Thus, all of the output lines WL126, VL127, and UL128 are set to the LOW level. As a result, the upper transistors 106, 108, 110 connected to the motor power supply 105 in FIG. 2 are turned off, and the lower transistors 107, 109, 111 connected to GND are turned on, thereby lower transistors. A regenerative current as a short brake can be supplied to 107, 109, and 111.

  In addition, the output signal 381 from the output suppression unit 380 in FIG. The signals 502, 503, 504, 505, 506, and 507 for driving the UL 128 can be controlled to be in a LOW state so that no regenerative current flows.

  FIG. 1 is a flowchart showing the processing of the CPU 200 when the motor is stopped in this embodiment. As shown in the figure, the apparatus of this embodiment first stops the clock signal 212 (S2, S3) and decelerates the rotation speed of the motor. Then, it waits for the rotational speed of the DC brushless motor to decrease to a predetermined rotational speed, and in response to the detection result of the motor rotational speed detection unit 101 becoming the first rotational speed (target rotational speed 408) (S6). ), The short brake is started to stop the rotation of the motor (S7, S8).

  FIG. 9 is a flowchart showing the processing of the CPU 200 when the motor is stopped in the modification of this embodiment. As shown in the figure, the deformation device first stops the clock signal (S12, S13) and decelerates the rotation speed of the motor. And it waits for the rotational speed of DC brushless motor to fall to predetermined 1st rotational speed (S16). In response to the detection result of the motor rotation speed detection unit 101 having reached the predetermined first rotation speed, reverse brake is started (S17), and the rotation speed of the DC brushless motor is decreased to the predetermined second rotation speed. It waits to do (S18). In response to the detection result of the motor rotation speed detection unit 101 reaching the predetermined second rotation speed, the short brake is started and the rotation is stopped (S19, S20).

  As described above, according to this embodiment and its modification, the output driver is controlled so that the phase current does not flow in the motor winding by stopping the supply of the clock for driving the DC brushless motor, and the current is supplied to the motor winding. It is possible to reduce the stress of semiconductors such as transistors and FETs used for flow. Furthermore, it is not necessary to consider the enlargement of the semiconductor package due to the allowable heat loss due to the regenerative current during short brakes when the motor is stopped, and the cost can be reduced.

  In addition, when stopping the rotation of the motor, the rotation speed of the motor is detected by supplementing it with an FG detection circuit from the FG pattern, which is a conventional circuit, and when a predetermined motor rotation speed is reached, a short brake or By applying reverse brake, the motor can be stopped earlier than before. For this reason, low noise due to shortening of the motor driving time is eliminated, and also the transition time in the motor stop stage (mechanical inertial rotation that cannot be electrically controlled) can be shortened, so there is also an advantage that the transition time to the next operation can be shortened. .

An “image forming apparatus” that is Embodiment 2 will be described.
FIG. 10 is a cross-sectional view illustrating a schematic configuration of the image forming apparatus (printer) according to the present exemplary embodiment.
FIG. 10 shows a main body 600 of the image forming apparatus, a main body substrate unit 602, and a paper transport cassette 601. Current detection means is mounted on the main body substrate unit 602.

  When an image formation start signal is issued from a personal computer connected to the image forming apparatus or an operation unit (not shown) to perform a copying operation, the paper feeding operation is started from the selected cassette or manual feed tray. For example, a case where paper is fed from a cassette will be described. First, the transfer material P is sent out one by one from the cassette by a pickup roller. The recording medium P is guided between the paper feed guides 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 starts forming an image. The rotation timing is set so that the recording medium P and the toner image primarily transferred onto the intermediate transfer belt 8 from the image forming unit exactly coincide with each other in the secondary transfer region. On the other hand, when an image forming operation start signal is issued in the image forming unit, an electrostatic latent image is formed on each color drum. The image forming timing in the sub-scanning direction is determined and controlled in accordance with the distance between the image forming units in order from the photosensitive drum (Y in the present embodiment) located upstream in the rotation direction of the intermediate transfer belt 8. . Further, the writing timing of each drum in the main scanning direction is generated and controlled using a single BD sensor signal (arranged in BK in this embodiment) by a circuit operation (not shown).

  The formed electrostatic latent image is developed. The drum motor for driving the photosensitive drums 32a, 32b, 32c, and 32d is a DC brushless motor, and is also a three-phase brushless motor. The DC brushless motor according to the first embodiment and those described in FIG. 2, FIG. 4, and FIG. The circuit is the target. When the photosensitive drum is in contact with the cleaning blade, when the photosensitive drum is stopped from rotating, noise may be generated just before the stop due to friction of the contact portion of the cleaning blade. For this reason, by shortening the stop time immediately before the stop according to the first embodiment, it is possible to shorten the generation time of abnormal noise, and it is possible to suppress the sound that humans feel uncomfortable.

  The toner image formed on the photosensitive drum 32a at the most upstream is primarily transferred to the intermediate transfer belt 8 in the primary transfer region by the primary transfer charger 5a to which a high voltage is applied. The primarily transferred toner image is conveyed to the next primary transfer region 5b. In this case, the image formation is delayed by 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 by aligning the resist 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 recording medium P enters the secondary transfer region (secondary transfer roller 12) and contacts the intermediate transfer belt 8, a high voltage is applied to the secondary transfer roller 12 in accordance with the passing timing of the recording medium P. Then, the four color toner images formed on the intermediate transfer belt 8 by the above-described process are transferred onto the surface of the recording medium P. After the secondary transfer, the recording medium P is accurately guided to the fixing roller nip portion by the conveyance guide 34. The toner image is fixed on the surface of the recording medium by the heat of the fixing film 16a and the pressure roller 16b and the pressure of the nip. Thereafter, the recording medium P is conveyed by the outer paper discharge roller 21, and the recording medium P is discharged to the outside of the apparatus to complete a series of image forming operations.

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

  The detailed operation in the present embodiment and the above-described rotation stop control of the DC brushless motor are the same as those in the first embodiment, and a description thereof will be omitted.

101 Motor Rotation Speed Detection Unit 104 Clock Generation Unit 224 Driver Unit 501 Signal 530 for Starting Short Braking from CPU 200 Input Signal for Stopping Clock

Claims (3)

A DC brushless motor drive control device in which the rotation speed is controlled in accordance with a clock signal instructing the rotation speed,
When the rotation of the DC brushless motor is stopped, first, the clock signal is stopped, waiting for the rotation speed of the DC brushless motor to decrease to a predetermined rotation speed, and short-circuiting when the predetermined rotation speed is reached. A DC brushless motor drive control device comprising control means for controlling to start rotation and stop rotation. A DC brushless motor drive control device in which the rotation speed is controlled in accordance with a clock signal instructing the rotation speed,
When the rotation of the DC brushless motor is stopped, first, the clock signal is stopped and the DC brushless motor waits for the rotation speed of the DC brushless motor to drop to a predetermined first rotation speed, and then the predetermined first rotation speed. When reverse rotation brake is reached, the reverse rotation brake is started to wait for the rotational speed of the DC brushless motor to fall to the predetermined second rotational speed, and short brake is started when the predetermined second rotational speed is reached. And a DC brushless motor drive control device comprising control means for controlling the rotation to stop.   An image forming apparatus comprising the DC brushless motor drive control device according to claim 1.

Images