JP2005160255A - Motor control arrangement, motor control method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten the time required for bringing up/down and the changing speed of a DC brushless motor by improving response of the DC brushless motor. <P>SOLUTION: A DC brushless motor control system comprises a target rotational speed detecting circuit 111, a difference detecting circuit 112, a digital signal generating circuit 113, a D/A conversion circuit 114, a pulse width modulation circuit 115, a drive circuit 116, a rotational speed detecting circuit 118, and an amplifier 119. When the difference detecting circuit 112 detects a difference between the target rotational speed and the detected rotational speed of a DC brushless motor 117, the digital signal generating circuit 113 generates a digital signal corresponding to the difference, and the D/A conversion circuit 114 converts the digital signal to an analogue signal while the pulse width modulation circuit 115 generates PWM signal having the pulse width corresponding to the analogue signal. The drive circuit 116 controls a drive power of an FET selected by a phase excitation signal from a plurality of FETs using the PWM signal, for driving the DC brushless motor 117. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a motor control device, a motor control method, and a program suitable for shortening the startup, shutdown, and shift time of a DC brushless motor.

  Conventionally, DC brushless motors have been installed and used in various devices such as copiers, printers, personal computer peripherals, and home appliances because of their advantages of high rotational stability and long life. A DC brushless motor is usually composed of a unit including a rotating body, a driver, and a PLL (Phase Lock Loop) control unit, and is turned on / off from the main body control unit on the device side where the DC brushless motor is mounted. Operates according to the signal. Note that the rotation speed may be set by supplying a clock to the DC brushless motor from the outside. The configuration of the DC brushless motor is shown in FIG.

  FIG. 13 is a block diagram illustrating a configuration of a DC brushless motor and a control system according to a conventional example.

  In FIG. 13, the control system of the DC brushless motor 2004 includes a clock generation circuit 2000, a PLL circuit 2001, a pulse width modulation circuit 2002, a drive circuit 2003, a Hall element 2005, and a Hall amplifier 2006.

  Hall element 2005 detects the rotational phase and rotational speed of DC brushless motor 2004. The hall amplifier 2006 amplifies a weak hall voltage (about several tens of mV) output from the hall element 2005. The clock generation circuit 2000 generates a clock for determining a target rotation speed of the DC brushless motor. The PLL circuit 2001 outputs an analog voltage corresponding to the difference between the clock generated by the clock generation circuit 2000 and the rotation speed and rotation phase of the DC brushless motor 2004 amplified by the hall amplifier 2006.

  The pulse width modulation circuit 2002 generates a pulse waveform having a duty corresponding to the output of the PLL circuit 2001. The drive circuit 2003 is composed of a plurality of FETs and the like, selects a FET from the plurality of FETs based on the output (phase excitation signal) of the Hall amplifier 2006, and sets the drive power of the selected FET to a pulse width modulation circuit 2002. The DC brushless motor 2004 is driven by controlling with the output of.

  Recently, accelerator (acceleration) / dexel (deceleration) control for a DC brushless motor has become possible, and advanced control such as fine adjustment of the phase of the rotating body of the DC brushless motor has been achieved. FIG. 14 shows an example in which this DC brushless motor control is applied to laser scanner motor (polygon motor) control of a laser beam printer that performs color image formation.

  FIG. 14 is a block diagram showing a configuration of a DC brushless motor and a control system according to another conventional example.

  In FIG. 14, the control system of the DC brushless motor 2021 includes a BD sensor 2010, an ITOP sensor 2011, a ref_BD generation / phase difference detection circuit 2012, an ACC / DEC table 2013, a charge pump circuit 2014, a system control circuit 2015, a selector 2016, and a clock. A generation circuit 2017, a PLL circuit 2018, a pulse width modulation circuit 2019, a drive circuit 2020, a Hall element 2022, and a Hall amplifier 2023 are provided.

  The BD sensor 2010 is disposed on a scanning line that scans the laser beam on the photosensitive member of the laser beam printer, and generates a synchronization signal (BD signal) in the main scanning direction. The ITOP sensor 2011 detects a mark provided on the intermediate transfer belt and generates a reference signal (ITOP signal) in order to determine the leading edge timing of the image (timing to form a latent image by irradiating the photosensitive member with laser light). To do. The ref_BD generation / phase difference detection circuit 2012 generates a signal having a predetermined BD period (Ref_BD signal) in synchronization with the ITOP signal, and detects the phase difference between the BD signal detected by the BD sensor 2010 and the ref_BD signal. The ACC / DEC table 2013 outputs an ACC signal (accelerator signal) or a DEC signal (dexel signal) corresponding to the phase difference.

  The charge pump circuit 2014 includes a capacitor (not shown), and generates an analog signal corresponding to the time when the ACC signal or DEC signal is applied. The selector 2016 selects either the output of the charge pump circuit 2014 or the output of the PLL circuit 2018 according to a command from the system control circuit 2015. The operations of the pulse width modulation circuit 2019, the drive circuit 2020, the Hall element 2022, and the Hall amplifier 2023 are the same as the operations of the corresponding units in FIG.

  By performing the control as described above, in the laser beam printer that forms a color image, the writing position of the first color, which is the latent image forming position on the photoconductor, and the writing position of the second and subsequent colors are exactly the same. Thus, an output image without color misregistration is realized.

Various techniques have been proposed for the accelerator / dexel control for the DC brushless motor described above (see, for example, Patent Document 1).
JP 2002-272162 A

  However, in the above conventional example, when changing the rotational speed of the DC brushless motor, the capacitor included in the charge pump circuit is charged / discharged to generate a signal corresponding to the time when the ACC signal or DEC signal is applied. There must be. Since charging and discharging of the capacitor takes time, there is a problem that the response of the DC brushless motor deteriorates. For this reason, it takes time to control the DC brushless motor so as to achieve the target rotational speed and rotational phase, which imposes limitations on the operability and productivity of equipment equipped with the DC brushless motor.

  An object of the present invention is to provide a motor control device, a motor control method, and a program capable of improving the responsiveness of a DC brushless motor and shortening the start-up, shutdown, and shift times of the DC brushless motor. There is.

  In order to achieve the above-described object, the present invention provides a difference between a detected rotational speed and a target rotational speed in a motor control device that drives the motor based on a phase excitation signal and a drive control signal corresponding to the detected rotational speed of the motor. Differential detection means for detecting the digital signal, digital signal generation means for generating a digital signal corresponding to the difference, conversion means for converting the digital signal into an analog signal, and the drive control having a pulse width corresponding to the analog signal Drive control means for generating a signal.

  Further, in the present invention, the digital signal generating means generates a digital signal so that when the motor is started up, if the detected rotational speed is lower than a target rotational speed, the driving force for the motor is increased. When the detected rotational speed is higher than the target rotational speed, the digital signal is generated so that the driving force for the motor is low.

  The present invention also provides a difference detection means for detecting a difference between a detected rotation speed and a target rotation speed in a motor control device for driving the motor based on a phase excitation signal and a drive control signal corresponding to the detected rotation speed of the motor. Digital signal generation means for generating a digital signal corresponding to the difference; conversion means for converting the digital signal into a first analog signal; and acceleration / deceleration signal generation for generating an acceleration signal or a deceleration signal according to the difference Means, output means for outputting a second analog signal corresponding to the acceleration signal or the deceleration signal, selection means for selecting the first or second analog signal according to the driving status of the motor, and selection Drive control means for generating the drive control signal having a pulse width corresponding to the first or second analog signal.

  Further, the present invention is characterized in that the selection means selects the first analog signal when shifting the motor, and selects the second analog signal when rotating the motor normally. .

  In addition, the present invention is characterized by comprising control means for performing control so that signal switching by the selection means is not performed when the potential difference between the first and second analog signals is greater than or equal to a predetermined level.

  According to the present invention, when the potential difference between the first and second analog signals is greater than or equal to a predetermined level, the control means causes the second analog signal level to approach the first analog signal level. The acceleration / deceleration signal generating means is controlled.

  In the present invention, the control means may be configured to bring the first analog signal level closer to the second analog signal level when the potential difference between the first and second analog signals is greater than or equal to a predetermined level. The digital signal generating means is controlled.

  According to the present invention, the control means controls the digital signal generation means and the acceleration / deceleration signal generation means so as to eliminate the level difference when the potential difference between the first and second analog signals is greater than or equal to a predetermined level. It is characterized by doing.

  The present invention also provides a difference detection means for detecting a difference between a detected rotation speed and a target rotation speed in a motor control device for driving the motor based on a phase excitation signal and a drive control signal corresponding to the detected rotation speed of the motor. Drive control means for generating the drive control signal having a pulse width corresponding to the difference.

  Further, according to the present invention, the drive control means generates a drive control signal so that when the motor is started up, if the detected rotational speed is lower than the target rotational speed, the driving force for the motor is increased. When the detected rotation speed is higher than the target rotation speed, the drive control signal is generated so that the driving force with respect to the motor is reduced.

  The present invention also includes a plurality of drive means for driving the motor, selects a drive means to be operated from the plurality of drive means based on the phase excitation signal, and selects the drive means selected based on the drive control signal. The driving force is controlled.

  According to the present invention, the motor is a DC brushless motor.

  According to the present invention, the rotational speed of the motor is detected by a Hall element or a rotary encoder.

  Furthermore, the motor control device of the present invention generates speed detection means for detecting the rotation speed of the motor, difference detection means for detecting a difference between the detected rotation speed and the target rotation speed, and a digital signal corresponding to the difference. Digital signal generation means, conversion means for converting the digital signal into an analog signal, pulse width modulation means for generating a PWM signal having a pulse width corresponding to the analog signal, and a phase excitation signal corresponding to the detected rotational speed A configuration may be provided that includes a phase excitation signal generation unit to be generated and a drive unit that is selected based on the phase excitation signal and drives the motor with a driving force determined based on the PWM signal.

  Furthermore, the motor control device of the present invention generates speed detection means for detecting the rotation speed of the motor, difference detection means for detecting a difference between the detected rotation speed and the target rotation speed, and a digital signal corresponding to the difference. A digital signal generating means; a converting means for converting the digital signal into a first analog signal; an acceleration / deceleration signal generating means for generating an acceleration signal or a deceleration signal according to the difference; and the acceleration signal or the deceleration signal. Output means for outputting a second analog signal corresponding to the selected signal, selection means for selecting the first or second analog signal according to the driving status of the motor, and the selected first or second analog signal. A pulse width modulation means for generating a PWM signal having a pulse width according to the signal, a phase excitation signal generation means for generating a phase excitation signal according to the detected rotational speed, and a phase excitation signal based on the phase excitation signal. It is selected, the driving force which is determined based on the PWM signal may be configured to include a driving means for driving the motor.

  Furthermore, the motor control device of the present invention includes a speed detection means for detecting the rotational speed of the motor, a difference detection means for detecting a difference between the detected rotational speed and the target rotational speed, and a pulse having a pulse width corresponding to the difference. PWM signal generation means for generating a PWM signal having a width, phase excitation signal generation means for generating a phase excitation signal corresponding to the detected rotational speed, and a selection based on the phase excitation signal and determined based on the PWM signal It is good also as a structure provided with the drive means which drives the said motor with a drive force.

  According to the present invention, the conversion means for converting the digital signal corresponding to the difference between the detected rotation speed and the target rotation speed into an analog signal is provided, and a drive control signal having a pulse width corresponding to the analog signal is generated by the drive control means. This eliminates the time required to charge and discharge the capacitor when a charge pump circuit is provided to control the drive of the motor, thus improving the motor responsiveness and starting the motor. It is possible to shorten the time for falling and shifting.

  Further, according to the present invention, when the motor is started up, if the detected rotational speed is lower than the target rotational speed, a digital signal is generated so that the driving force for the motor is increased. On the other hand, when the detected rotational speed is high, the digital signal is generated so that the driving force to the motor is low, so that the motor can be started up and down in a short time.

  Further, according to the present invention, the first analog signal obtained by converting the digital signal corresponding to the difference between the detected rotational speed and the target rotational speed, or the acceleration signal or the deceleration signal corresponding to the difference according to the driving state of the motor. The second analog signal output based on the selected analog signal is selected and a drive control signal having a pulse width corresponding to the selected analog signal is generated to control the drive of the motor. In other words, according to the operation status of the motor. Since the conversion means for converting the digital signal into the first analog signal and the output means for outputting the second analog signal corresponding to the acceleration signal or the deceleration signal are properly used, the responsiveness improvement and the rotation stability of the motor are changed. Can be realized.

  In addition, according to the present invention, the first analog signal is selected when shifting the motor, and the second analog signal is selected when rotating the motor constantly. Stability can be achieved.

  In addition, according to the present invention, when the potential difference between the first and second analog signals is greater than or equal to a predetermined level, control is performed so that signal switching is not performed. Can be prevented.

  Further, according to the present invention, when the potential difference between the first and second analog signals is greater than or equal to a predetermined level, the acceleration / deceleration signal generating means is controlled so as to bring the second analog signal level closer to the first analog signal level. Therefore, as described above, it is possible to prevent a rapid change in the motor rotation speed.

  In addition, according to the present invention, when the potential difference between the first and second analog signals is greater than or equal to a predetermined level, the digital signal generating means is controlled to bring the first analog signal level closer to the second analog signal level. Similarly to the above, it is possible to prevent a rapid change in the motor rotation speed.

  In addition, according to the present invention, when the potential difference between the first and second analog signals is equal to or higher than a predetermined level, the digital signal generating unit and the acceleration / deceleration signal generating unit are controlled so as to eliminate the level difference. It is possible to prevent a sudden change in the motor rotation speed.

  In addition, according to the present invention, since the drive control signal having a pulse width corresponding to the difference is directly generated by the drive control means, the digital signal generation means for generating a digital signal and the conversion means for converting the digital signal into an analog signal are provided. It is not necessary to provide the motor, so that it is possible to reduce the speed of shifting of the motor and to realize cost reduction.

  Further, according to the present invention, when the motor is started up, if the detected rotational speed is lower than the target rotational speed, the drive control signal is generated so that the driving force for the motor is increased, and the target rotational speed is When the detected rotational speed is higher than the speed, the drive control signal is generated so that the driving force with respect to the motor is low, so that the motor can be started up and down in a short time.

  Further, according to the present invention, by applying the motor control device to the control of the DC brushless motor, it becomes possible to improve the responsiveness of the DC brushless motor and shorten the time for starting up, shutting down, and shifting. It is possible to realize the rotational stability of the DC brushless motor, it is possible to prevent the phenomenon that the rotational speed of the DC brushless motor suddenly changes and vibrates, etc. effective.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
A first embodiment of the present invention will be described. The motor control device of the present invention can be applied to any device including a DC brushless motor. However, in the present embodiment, a DC brushless motor is provided as a laser scanner motor (polygon motor) used for laser light irradiation on a photoconductor. An image forming apparatus (for example, a digital laser beam printer) is taken as an example. In addition, although the case where the printing method of the image forming apparatus is color will be described as an example, it is of course applicable to the case where the printing method is monochrome.

  FIG. 2 is a block diagram showing the internal structure of the image forming apparatus according to the present embodiment.

  In FIG. 2, an image forming apparatus 100 includes a photosensitive drum (hereinafter abbreviated as “photosensitive member”) 1, an intermediate transfer belt 2, a fixing device 5, a primary charger 7, an exposure device 8, a transfer device 10, a cleaner device 12, A developing unit 13, a secondary transfer roller 21, a recording paper cassette 23, an image control unit 38, and the like are provided.

  The photoreceptor 1 is an image carrier that is exposed by the exposure device 8 to form a latent image and is visualized as a toner image by the developing unit 13, and can be rotated in the direction of arrow A in the figure by a motor (not shown). It is configured. Around the photoreceptor 1, an intermediate transfer belt 2, a primary charger 7, an exposure device 8, a transfer device 10, a cleaner device 12, and a developing unit 13 are disposed. The control of a DC brushless motor as a laser scanner motor provided in the exposure apparatus 8 will be described in detail later.

  The primary charger 7 charges the surface of the photoreceptor 1. The exposure device 8 exposes the surface of the photoreceptor 1 with laser light. The transfer device 10 transfers the toner image formed on the photoreceptor 1 to the intermediate transfer belt 2. The secondary transfer roller 21 transfers the toner image transferred on the intermediate transfer belt 2 to a recording sheet. The fixing device 5 thermally fixes the toner image transferred to the recording paper. The recording paper cassette 23 can store a plurality of recording papers and is configured to be detachable from the image forming apparatus 100. The image control unit 38 generates an image signal for adjusting the exposure amount of the exposure apparatus 8.

  The developing unit 13 is configured as a rotary developing device including four developing devices 13Y, 13M, 13C, and 13K for performing full color development, and is rotated in the direction of arrow R in the figure by the motor 42. The developing devices 13Y, 13M, 13C, and 13K develop the latent images formed on the surface of the photoreceptor 1 with toners of Y (yellow), M (magenta), C (cyan), and K (black), respectively.

  The four color toner images developed on the photosensitive member 1 by the developing unit 13 are sequentially transferred to the intermediate transfer belt 2 as an intermediate transfer member by the transfer device 10 to be superimposed. The recording paper stored in the recording paper cassette 23 is pulled up one by one to a position where it contacts the pickup roller 24 by driving the lifter motor 40. The recording paper fed from the recording paper cassette 23 to the conveyance path by the pickup roller 24 is fed to a nip portion, that is, a contact portion between the secondary transfer roller 21 and the intermediate transfer belt 2 by a pair of rollers 25 and 26. The toner image formed on the intermediate transfer belt 2 is transferred onto the recording paper at the nip portion, thermally fixed by the fixing device 5, and then discharged from the discharge port to the outside of the image forming apparatus.

  The image forming operation in the image forming apparatus will be described in detail. First, a voltage is applied to the primary charger 7 to negatively charge the surface of the photoreceptor 1 uniformly with a predetermined charging portion potential. Subsequently, the exposure apparatus 8 formed of a laser scanner adjusts the exposure amount based on the image signal generated by the image control unit 38 so that the charged image portion on the photosensitive member 1 has a predetermined exposure portion potential. Thus, exposure is performed to form a latent image corresponding to the image portion.

  The image forming timing of the image forming apparatus is controlled based on an ITOP signal (sub-scanning reference signal) indicating a predetermined reference position (mark formation position) on the intermediate transfer belt 2. The intermediate transfer belt 2 is stretched over rollers composed of a drive roller 17, a tension roller 18, and a backup roller 19, and a portion between the tension roller 18 and the backup roller 19 facing the intermediate transfer belt 2 has an intermediate portion. An ITOP sensor 36, which is a reflective position sensor that outputs the ITOP signal when a predetermined reference position on the transfer belt 2 is detected, is disposed.

  A developing bias set in advance for each color is applied to the developing devices 13Y to 13K of the developing unit 13, and the latent image formed on the photosensitive member 1 is rotated by the photosensitive member 1 with the developing devices 13Y to 13Y. The latent image is visualized as a toner image by being developed with toner when passing a position facing 13K. The visualized toner image is transferred to the intermediate transfer belt 2 by the transfer device 10, further transferred to the recording paper by the secondary transfer roller 21, and then fed to the fixing device 5. At the time of full-color printing in which an image is formed on recording paper with four color toners, the toner images are transferred onto the recording paper after the four color toners are superimposed on the intermediate transfer belt 2.

  The toner remaining on the photosensitive member 1 is removed and collected by the cleaner device 12, and finally, the photosensitive member 1 is uniformly discharged to near 0 volts by a neutralizing device (not shown), so that the next image forming cycle can be performed. Prepare.

  Next, control of a DC brushless motor used as a laser scanner motor in the exposure apparatus 8 of the image forming apparatus, which is characteristic of the present embodiment, will be described.

  FIG. 3 is a schematic diagram showing a configuration of the exposure device 8 of the image forming apparatus.

  In FIG. 3, the exposure apparatus 8 includes a semiconductor laser 101, a polygon mirror 102, a DC brushless motor 117, and an imaging lens 104.

  The semiconductor laser 101 emits laser light. Laser light emitted from the semiconductor laser 101 is reflected by the polygon mirror 102. The polygon mirror 102 is directly connected to the rotating shaft of the DC brushless motor 117, and the laser beam is scanned through the polygon mirror 102 by the rotation of the DC brushless motor 117. The laser beam reflected by the polygon mirror 102 is imaged on the photosensitive member 1 by the imaging lens 104. The BD sensor 105 (see FIG. 1) outputs a horizontal synchronization signal (BD signal) that serves as a reference for forming (writing) a latent image on the photosensitive member 1 by laser light.

  FIG. 1 is a block diagram showing a configuration of a DC brushless motor as a laser scanner motor of the exposure device 8 of the image forming apparatus and a control system.

  In FIG. 1, the control system of the DC brushless motor 117 includes an ITOP sensor 36, a BD sensor 105, a system control circuit 110, a target rotation speed setting circuit 111, a difference detection circuit 112 (difference detection means), and a digital signal generation circuit 113 (digital). Signal generation means), D / A conversion circuit 114 (conversion means), pulse width modulation circuit 115 (drive control means), drive circuit 116, rotation speed detection circuit 118, amplifier 119, and ref_BD generation / phase difference detection circuit 120. ing.

  The system control circuit 110 controls the entire image forming apparatus, and executes processing shown in the flowchart of FIG. 8 based on a program. The digital signal generation circuit 113 includes a plurality of speed difference tables and a phase correction table. The drive circuit 116 includes a plurality of FETs (a plurality of drive means). As the rotation speed detection circuit 118, a Hall element, a rotary encoder, or another configuration may be used. The functions of other circuits will be described with reference to the flowchart of FIG.

  Next, the control flow of the DC brushless motor 117 of the image forming apparatus will be described with reference to the flowchart of FIG.

  First, the target rotation speed setting circuit 111 sets the target rotation speed of the DC brushless motor 117 based on information from the system control circuit 110 (step S1). On the other hand, the current rotational speed of the DC brushless motor 117 is constantly detected by the rotational speed detection circuit 118 (step S2).

  Accordingly, the difference detection circuit 112 detects the difference between the target rotation speed of the DC brushless motor 117 and the current rotation speed (step S3). From the output of the difference detection circuit 112, it is possible to recognize how fast the current rotational speed is relative to the target rotational speed or how slow it is. When the difference is output from the difference detection circuit 112, the digital signal generation circuit 113 generates a multi-bit digital signal corresponding to the output of the difference detection circuit 112 (step S4), and further the D / A conversion circuit 114. Thus, the output signal of the digital signal generation circuit 113 is converted into an analog signal (step S5).

  Next, in the pulse width modulation circuit 115, the analog signal output from the D / A conversion circuit 114 is compared with a triangular wave or a waveform conforming thereto, and a PWM (Pulse Width Modulation) signal having a desired duty based on the comparison result. Is generated and output to the drive circuit 116 (step S6). In this case, when the rotational speed of the DC brushless motor 117 is desired to be increased, the duty of the PWM signal is controlled to be increased, and when the rotational speed is desired to be decreased, the duty of the PWM signal is controlled to be decreased.

  On the other hand, the output signal of the rotational speed detection circuit 118 is amplified by an amplifier 119 and output to the drive circuit 116 as a phase excitation signal. Then, the FET to be driven is selected from the plurality of FETs in the drive circuit 116 by the phase excitation signal, and the drive duty of the selected FET is determined by the PWM signal output from the pulse width modulation circuit 115. In this way, the DC brushless motor 117 is driven and controlled (step S7).

  Next, the control at the time of starting, falling, and fine adjustment of the DC brushless motor 117 of the present embodiment will be described in detail with reference to FIGS.

  FIG. 4 is a graph of the speed difference table of the digital signal generation circuit 113, and shows the relationship between the output of the digital signal generation circuit 113 and the rotation speed difference. FIG. 5 is a diagram illustrating a PWM waveform generation example of the pulse width modulation circuit 115. FIG. 6 is a diagram illustrating the timing of the BD signal and the Ref_BD signal. FIG. 7 is a table chart for phase correction of the digital signal generation circuit 113, and shows the relationship between the output of the digital signal generation circuit 113 and the phase difference.

(1) At startup
A case where the DC brushless motor 117 is started up from a stopped state to a rotational speed of 15000 rpm will be described. In this case, the target rotational speed of the DC brushless motor 117 is 15000 rpm, and the current rotational speed is zero. Therefore, the output (difference) of the difference detection circuit 112 is 15000-0 = 15000.

  As described above, the digital signal generation circuit 113 has a plurality of reference speed difference tables (FIG. 4) for determining a digital output corresponding to the difference between the target rotation speed of the DC brushless motor 117 and the current rotation speed. I have. The reason for providing a plurality of speed difference tables is that even if the difference between the target rotation speed detected by the difference detection circuit 112 and the current rotation speed is the same, the DC brushless motor 117 is driven by the current rotation speed of the DC brushless motor 117. This is because the driving force to be applied is different.

  FIG. 4 shows a speed difference table when the current rotation speed of the DC brushless motor 117 is 0 to 3000 rpm. Since the difference between the target rotational speed of the DC brushless motor 117 and the current rotational speed is 15000 as described above, it can be seen that the output value of the digital signal generation circuit 113 is 1Eh. For example, the D / A conversion circuit 114 is configured to output 0V when the input from the digital signal generation circuit 113 is 00h, and output 5V when the input is FFh. Therefore, the D / A conversion circuit 114 outputs 0.588 V when the input is 1 Eh.

  As shown in FIG. 5A, the pulse width modulation circuit 115 compares the preset basic triangular wave with the input voltage 0.588V from the D / A conversion circuit 114, and the basic triangular wave is input. It outputs a digital signal that is “H” when the voltage is higher than the voltage and “L” when the basic triangular wave is lower than the input voltage. At the time of start-up, the output waveform of the pulse width modulation circuit 115 becomes a waveform with a high duty like “difference plus (acceleration)” shown in FIG.

  That is, when the current rotational speed is lower than the set target rotational speed of the DC brushless motor 117, such as when the DC brushless motor 117 is started, control is performed to increase the drive duty of the FET in the drive circuit 116. Therefore, the DC brushless motor 117 can be started up in a short time. Further, when the current rotational speed approaches the set target rotational speed of the DC brushless motor 117, an overshoot is performed so as to gradually decrease the drive duty of the FET in the drive circuit 116. This is effective in starting the DC brushless motor 117 in a short time.

(2) At the time of falling
When the DC brushless motor 117 is lowered, the DC brushless motor 117 can be lowered in a short period of time by performing a reverse control to that at the time of starting. That is, when the current rotational speed is higher than the set target rotational speed of the DC brushless motor 117 at the time of falling, the drive duty of the FET in the drive circuit 116 is controlled to be low.

(3) At the time of fine adjustment Since this image forming apparatus has four colors of toner used for image formation, one polygon mirror 102 and one photosensitive member 1, the developing unit 13 is used to improve image quality. Therefore, it is necessary to place the second and subsequent toners on the Y toner to be developed first without causing any deviation. Therefore, in this image forming apparatus, the timing at which the laser beam output from the exposure device 8 irradiates the first line on the photosensitive member 1 is the same for all colors with reference to the ITOP signal that is the sub-scanning reference signal. As described above, the phase of the DC brushless motor 117 is adjusted.

  Conventionally, as described above, when adjusting the phase of a DC brushless motor, an acceleration / deceleration signal for accelerating / decelerating the DC brushless motor is converted into an analog signal by a charge pump circuit. However, since it takes time to charge and discharge the capacitor in the charge pump circuit, it takes 200 to 300 ms from the start to the end of the phase adjustment. For this reason, there has been a problem that it takes time to switch colors during image formation, which reduces productivity.

  On the other hand, in this embodiment, instead of providing a charge pump circuit in the control system of the DC brushless motor 117, a D / A conversion circuit 114 is provided, and an acceleration / deceleration signal for accelerating / decelerating the DC brushless motor 117 is provided as D The conventional problem is solved by converting it to an analog signal by the / A conversion circuit 114.

  The ITOP signal shown in FIG. 6 is an output signal of the ITOP sensor 36. The Ref_BD signal has an “L” period of 4 clocks after the output of 4 clocks of the system clock (not shown) from the falling edge of the ITOP signal, and thereafter, “L” for 4 clocks every 160 μs which is the horizontal synchronization period. "A signal having a section. By correcting the phase of the actual BD signal so as to have the same timing as that of the Ref_BD signal, an image without color misregistration can be obtained.

  The ref_BD generation / phase difference detection circuit 120 counts the system clock that is reset by the falling edge of the Ref_BD signal, the counter value of the counter acquired at the falling timing of the BD signal, and a preset value (for example, described later) And a comparator for comparing the counter value 3999). As the system clock, for example, a clock with a frequency of 50 MHz is used, so the period of one clock is 20 ns. Therefore, the counter is reset when the system clock is counted from 0 to 7999.

  The ref_BD generation / phase difference detection circuit 120 operates when the timing when the BD signal becomes “L” is a counter value 0 to 3999 (mode 1) and when the counter value is 4000 to 7999 (mode 2). Different. As shown in FIG. 6, when the BD signal becomes “L” between the counter values 4000 to 7999, the phase of the BD signal is delayed more quickly to the phase of the Ref_BD signal. Because it can. Conversely, when the BD signal becomes “L” between the counter values 0 to 3999, control is performed so that the phase of the BD signal is advanced.

  Therefore, as shown in FIG. 6, the ref_BD generation / phase difference detection circuit 120 sets the phase of the BD signal with respect to the counter value 0 with reference to the falling edge of the Ref_BD signal in mode 1 (counter value 0 to 3999). In the mode 2 (counter value 4000 to 7999), information indicating the phase of the BD signal with respect to the counter value 7999 with respect to the falling edge of the Ref_BD signal is output.

  For example, if the BD signal becomes “L” when the counter value is 1000, the ref_BD generation / phase difference detection circuit 120 operates in mode 1 and outputs 0−1000 = −1000 as phase information. When the BD signal becomes “L” when the counter value is 5999, the ref_BD generation / phase difference detection circuit 120 operates in mode 2 and outputs 7999-5999 = 2000 as phase information. . When the sign of the phase information is negative, the DC brushless motor 117 is accelerated, and when the sign of the phase information is positive, the DC brushless motor 117 is decelerated so that the digital signal at the next stage of the ref_BD generation / phase difference detection circuit 120 The generation circuit 113 and later operate.

  As described above, the digital signal generation circuit 113 also includes a phase correction table in addition to the speed difference table. When the DC brushless motor 117 performs phase correction, the digital signal generation circuit 113 refers to the phase correction table instead of the speed difference table. Works like this. FIG. 7 shows a phase correction table.

  As described above, when the ref_BD generation / phase difference detection circuit 120 outputs the phase information 2000, the digital signal generation circuit 113 refers to the phase correction table of FIG. 7 and outputs the digital signal value D5h. Thereafter, similarly to the above-described start-up, an analog signal corresponding to D5h is generated by the D / A conversion circuit 114, and a PWM signal (pulse signal) having a duty corresponding to the analog signal is generated by the pulse width modulation circuit 115. Generate by. Then, similarly to the start-up, the phase of the DC brushless motor 117 is controlled by controlling the drive circuit 116.

  By performing such control, the first color writing position, which is the latent image forming position on the photoconductor 1, is accurately matched with the second and subsequent writing positions, and an output image without color misregistration is realized. Yes. Further, the D / A conversion circuit 114, which has better responsiveness compared to the charge pump circuit, performs control to generate an analog signal to be input to the pulse width modulation circuit 115, which is required for phase matching of the DC brushless motor 117. Time can be reduced and productivity of the image forming apparatus can be improved.

  As described above, according to the present embodiment, the DC brushless motor control system converts the digital signal corresponding to the difference between the detected rotational speed of the DC brushless motor 117 and the target rotational speed into an analog signal. A conversion circuit 114 is provided, and a charge pump circuit is provided to drive and control the DC brushless motor 117 by generating a PWM signal for determining the drive duty of the FET of the drive circuit 116 from the analog signal by the pulse width modulation circuit 115. In this case, the time required for charging / discharging the capacitor can be eliminated, so that the response of the DC brushless motor 117 can be improved, and the start-up / down / shift time of the DC brushless motor 117 can be shortened. Is possible.

[Second Embodiment]
FIG. 9 is a block diagram showing the configuration of a DC brushless motor and a control system used in the laser scanner motor of the exposure apparatus 8 of the image forming apparatus according to the second embodiment of the present invention.

  In FIG. 9, the control system of the DC brushless motor 117 includes an ITOP sensor 36, a BD sensor 105, a system control circuit 110 (control means), a target rotational speed setting circuit 111, a difference detection circuit 112 (difference detection means), and a digital signal generation. Circuit 113 (digital signal generation means), D / A conversion circuit 114 (conversion means), pulse width modulation circuit 115 (drive control means), drive circuit 116, rotation speed detection circuit 118, amplifier 119, ref_BD generation / phase difference detection The circuit 120 includes an analog selector 201 (selection means), a charge pump circuit 202 (output means), an acceleration / deceleration signal generation circuit 203 (acceleration / deceleration signal generation means), an A / D conversion circuit 204, and a comparison circuit 205.

  This embodiment is different from the first embodiment described above in that an analog selector 201, a charge pump circuit 202, an acceleration / deceleration signal generation circuit 203, an A / D conversion circuit 204, and a comparison circuit 205 are added. To do. Since the other elements of the present embodiment are the same as the corresponding ones of the first embodiment (FIG. 1) described above, description thereof is omitted.

  In the first embodiment described above, an analog signal is generated by the D / A conversion circuit 114, and a PWM signal is generated from the analog signal by the pulse width modulation circuit 115. On the other hand, in the present embodiment, the system control circuit 110 switches the outputs of the D / A conversion circuit 114 and the charge pump circuit 202 according to the situation.

  The D / A conversion circuit 114 and the charge pump circuit 202 can be selectively used when the DC brushless motor 117 needs to be changed in a short period of time, such as when the DC brushless motor 117 is started up, down, or phase aligned. When the DC brushless motor 117 is being driven at a steady rotational speed, the charge pump circuit 202 is used. This is because the DC brushless motor 117 is driven at a steady rotational speed at which image formation is performed and the charge pump circuit 202 having low response is used to avoid a sensitive response of the DC brushless motor 117 and high frequency noise is generated in the output image. This is to prevent it from appearing.

  The acceleration / deceleration signal generation circuit 203 charges an accelerator signal (acceleration signal) or a dexel signal (deceleration signal) corresponding to the difference between the target rotation speed of the DC brushless motor 117 detected by the difference detection circuit 112 and the current rotation speed. Output to the pump circuit 202. The charge pump circuit 202 outputs an analog signal corresponding to the input accelerator signal (acceleration signal) or dexel signal (deceleration signal) to the analog selector 201 and the A / D conversion circuit 204.

  The analog selector 201 selectively switches between an analog signal output from the D / A conversion circuit 114 and an analog signal output from the charge pump circuit 202. The A / D conversion circuit 204 converts the analog signal output from the charge pump circuit 202 into a digital signal. The comparison circuit 205 compares the output of the digital signal generation circuit 113 and the output of the A / D conversion circuit 204, and if there is a difference of a predetermined amount or more between both outputs, the analog selector regardless of the switching instruction of the system control circuit 110 Control is performed so that 201 does not switch.

  Next, control of the DC brushless motor 117 of the present embodiment will be described in detail with reference to FIG.

  First, the target rotational speed is given to the target rotational speed setting circuit 111 by the system control circuit 110. Since the output voltage of the rotation speed detection circuit 118 (for example, a Hall element) is weak, the amplifier 119 amplifies the output voltage. The difference detection circuit 112 detects the difference between the output of the amplifier 119 and the target rotation speed set by the target rotation speed setting circuit 111 and inputs the difference to the acceleration / deceleration signal generation circuit 203. The acceleration / deceleration signal generation circuit 203 outputs an accelerator signal or a dexel signal corresponding to the difference to the charge pump circuit 202. The charge pump circuit 202 outputs an analog signal corresponding to the acceleration / deceleration signal.

  The difference detection circuit 112 also inputs the difference to the digital signal generation circuit 113. Similar to the first embodiment described above, the digital signal generation circuit 113 refers to the speed difference table and outputs a digital signal. The D / A conversion circuit 114 converts the digital signal into an analog signal. Analog signals respectively output from the D / A conversion circuit 114 and the charge pump circuit 202 are input to the analog selector 201. The system control circuit 110 controls input selection (signal switching) of analog signals output from the D / A conversion circuit 114 and the charge pump circuit 202 in the analog selector 201.

  That is, based on the control of the system control circuit 110, the analog signal of the D / A conversion circuit 114 is selected when the DC brushless motor 117 needs to be changed in a short time, such as starting up, shutting down, or phase matching. When the DC brushless motor 117 is being driven at a steady rotational speed, the analog selector 201 is switched to select the analog signal of the charge pump circuit 202.

  In addition, if there is a difference between the two analog signal values input to the analog selector 201 when the signal is switched by the analog selector 201, the rotational speed of the DC brushless motor 117 changes suddenly and vibrates. In order to prevent this, the comparison circuit 205 compares the digital signal obtained by A / D converting the analog signal output from the charge pump circuit 202 with the A / D conversion circuit 204 and the digital signal output from the digital signal generation circuit 113. If the difference between the two signals exceeds a predetermined amount, the analog selector 201 is controlled by the comparison circuit 205 so that the signal is not switched by the analog selector 201 even if the system control circuit 110 instructs switching. .

  When the system control circuit 110 instructs switching as described above, if there is a difference of a predetermined amount or more between the two signals, the comparison circuit 205 sends the acceleration / deceleration signal generation circuit 203 and the digital signal generation circuit 113 to each other. By giving an instruction, control is made so that there is no difference between the two signals. At this time, the digital signal generation circuit 113 is controlled so that the output continuously changes from the value before switching. As described in the first embodiment, the digital signal generation circuit 113 also generates ref_BD generation / phase difference detection for the phase difference signal between the ref_BD signal and the BD signal generated from the output signals of the BD sensor 105 and the ITOP sensor 36. Input from the circuit 120. The operations after the analog selector 201 are the same as those in the first embodiment.

  As described above, according to the present embodiment, the D / A conversion circuit 114 and the charge pump circuit 202 are selectively used according to the operation state of the DC brushless motor 117, that is, the DC brushless motor 117 is started and started. The D / A conversion circuit 114 is used when the rotation speed needs to be changed in a short time such as lowering or phase alignment, and the charge pump circuit 202 is operated when the DC brushless motor 117 is driven at a steady rotation speed for image formation. As a result, the DC brushless motor 117 can be improved in responsiveness at the time of shifting and rotational stability at the time of image formation.

[Third Embodiment]
FIG. 10 is a block diagram showing the configuration of a DC brushless motor and a control system used in the laser scanner motor of the exposure apparatus 8 of the image forming apparatus according to the third embodiment of the present invention.

  In FIG. 10, the control system of the DC brushless motor 117 includes an ITOP sensor 36, a BD sensor 105, a system control circuit 110, a target rotational speed setting circuit 111, a difference detection circuit 112 (difference detection means), and a digital PWM circuit 250 (drive control). Means), a drive circuit 116, a rotation speed detection circuit 118, an amplifier 119, and a ref_BD generation / phase difference detection circuit 120.

  This embodiment is different from the first embodiment described above in that the digital signal generation circuit 113, the D / A conversion circuit 114, and the pulse width modulation circuit 115 are deleted and a digital PWM circuit 250 is added. To do. Since the other elements of the present embodiment are the same as the corresponding ones of the first embodiment (FIG. 1) described above, description thereof is omitted.

  In both the first and second embodiments described above, an analog signal input to the pulse width modulation circuit 115 is controlled. On the other hand, in the present embodiment, the PWM signal is not generated by the analog signal, but the PWM signal is directly generated digitally by the digital PWM circuit 250.

  The difference detection circuit 112 outputs a rotation speed difference detection output signal (see FIG. 11) corresponding to the difference between the target rotation speed of the DC brushless motor 117 and the current rotation speed. The ref_BD generation / phase difference detection circuit 120 outputs a phase difference detection output signal (see FIG. 11) corresponding to the phase difference between the ref_BD signal and the BD signal. The outputs of the difference detection circuit 112 and the ref_BD generation / phase difference detection circuit 120 are both input to the digital PWM circuit 250.

  The digital PWM circuit 250 outputs a PWM signal (pulse waveform) having a duty corresponding to the rotation speed difference detection output signal and the phase difference detection output signal, and determines the drive power of the drive circuit 116 at the next stage. In other words, when the DC brushless motor 117 is started up, if the detected rotational speed is lower than the target rotational speed, the digital PWM circuit 250 increases the duty so that the driving force to the DC brushless motor 117 by the driving circuit 116 is increased. If the detected rotational speed is higher than the target rotational speed when the DC brushless motor 117 is lowered when the PWM brush is generated, the PWM signal with a reduced duty so that the driving power to the DC brushless motor 117 by the drive circuit 116 is reduced. Is generated.

  FIG. 11 is a block diagram showing a detailed configuration of the digital PWM circuit 250.

  11, the digital PWM circuit 250 includes a clock generation unit 300, a counter 301, a table selection unit 302, a table selection unit 313, a table 303, a table 313, a comparator 304, a comparator 305, a comparator 306, a comparator 307, A JK flip-flop 308, a JK flip-flop (hereinafter abbreviated as JK-FF) 309, and a selector 310 are provided.

  The table selection unit 302, the table 303, the comparator 304, and the JK-FF 308 constitute a speed matching circuit that matches the target rotation speed of the DC brushless motor 117 and the current rotation speed, and the table selection unit 312 described above. The table 313, the comparator 307, and the JK-FF 309 constitute a phase matching circuit that performs phase matching between the ref_BD signal and the BD signal, and the clock generation unit 300, the counter 301, the comparator 305, the comparator 306, and the selector 310 include the speed This circuit is used in common by the matching circuit and the phase matching circuit.

  The clock generator 300 generates a clock. The counter 301 counts clocks generated from the clock generation unit 300. The table 303 includes a plurality of speed difference tables similar to those in the first embodiment. The table selection unit 302 receives the rotational speed difference detection output signal of the DC brushless motor 117 and the current speed signal, and determines which table to use from a plurality of tables constituting the table 303. The table 313 includes a plurality of tables for phase correction similar to those in the first embodiment. The table selection unit 312 receives the phase difference detection output signal of the DC brushless motor 117 and the current speed signal, and determines which table to use from a plurality of tables constituting the table 313.

  The comparator 304 compares the output of the counter 301 with the output of the table 303. The comparator 305 compares the output of the counter 301 with the register value 00h. The comparator 306 compares the output of the counter 301 with the register value ROT. The comparator 307 compares the output of the counter 301 with the output of the table 313. The outputs of the comparator 304 and the comparator 305 are input to the JK-FF 308, and a signal based on the logical relationship between the outputs is output to the selector 310. The JK-FF 309 receives the outputs of the comparator 305 and the comparator 307 and outputs a signal based on the logical relationship between the outputs to the selector 310. The selector 310 outputs the PWM signal to the drive circuit 116.

  Next, control of the DC brushless motor 117 of the present embodiment will be described in detail with reference to FIGS.

  First, the difference detection circuit 112 outputs a rotation speed difference output signal indicating the difference between the target rotation speed of the DC brushless motor 117 and the current rotation speed, and the DC brushless motor 117 detected by the rotation speed detection circuit 118 from the amplifier 119. The current speed signal indicating the current speed is input to the table selection unit 302 of the digital PWM circuit 250, respectively. The table selection unit 302 determines which table to use from a plurality of tables in the next-stage table 303. The table 303 outputs a digital value corresponding to the rotational speed difference to the comparator 304 using the determined table.

  On the other hand, the counter 301 counts the clock generated by the clock generator 300 and outputs the counter value to the comparators 304 to 307. The comparator 306 compares the counter value of the counter 301 with the register value ROT. When the counter value becomes the same as the register value ROT, the comparator 306 outputs an H pulse for one clock cycle and resets the counter 301. The register value ROT is a constant for determining the period of the PWM waveform.

  The comparator 305 compares the counter value of the counter 301 with a constant 00h, and outputs an H pulse to JK-FF308 and JK-FF309 when the counter value reaches 0. At this time, the output of JK-FF308 changes from L to H. The comparator 304 compares the counter value of the counter 301 with the output value of the table 303, and outputs an H pulse to the JK-FF 308 when the counter value becomes the same value as the output value of the table 303. At this time, the output of JK-FF308 changes to L. By operating in this way, a PWM signal having a waveform as shown in FIG. 12 can be output from JK-FF308.

  A PWM signal (PWM signal from the speed matching circuit) output from JK-FF 308 is input to selector 310. Further, the PWM signal (PWM signal from the phase matching circuit) output from the JK-FF 309 is also input to the selector 310. The selector 310 outputs the PWM signal from the JK-FF 309 only when phase matching between the Ref_BD signal and the BD signal is performed based on an instruction from the system control circuit 110, and otherwise, the selector 310 outputs the PWM signal from the JK-FF 308. Is output.

  Further, when the system control circuit 110 detects that the duty of the PWM waveform output from each of the JK-FF308 and JK-FF309 is more than a predetermined amount, the system control circuit 110 accompanies that the duty is more than a predetermined amount. In order to prevent the influence on the DC brushless motor 117, the selector 310 is not switched, and the duty of the PWM waveform output from each of the JK-FF308 and JK-FF309 approaches the comparator 304 and the comparator 307, respectively. The control for correcting is performed as follows. The system control circuit 110 performs control so that the selector 310 is switched after the correction is completed.

  Specifically, when shifting from speed control to phase control, the system control circuit 110 monitors the output difference from each table. If the output difference is large (duty is more than a predetermined amount) at the timing when the selector 310 is to be switched, the system control circuit 110 generates a correction amount corresponding to the output difference and supplies it to the comparator (for phase) 307. input. At this time, by switching the select signal connected to the comparator (for phase) 307 from the system control circuit 110, the value to be compared with the counter value inside the comparator (for phase) 307 is not the data from the table 313 but the system. The data is from the control circuit 110. The duty difference is reduced by repeating the above operation a plurality of times. Then, the selector 310 is switched when the difference is equal to or less than the predetermined amount.

  As described above, according to this embodiment, the digital PWM circuit 250 directly generates the PWM signal to be output to the drive circuit 116 that drives the DC brushless motor 117. It is not necessary to provide an A conversion circuit, so that the shift time of the DC brushless motor 117 can be shortened and the cost can be reduced.

[Other embodiments]
In the first to third embodiments, the image forming apparatus is described as an example of the apparatus on which the DC brushless motor is mounted. However, the image forming apparatus is not limited to the image forming apparatus. It can be applied to all devices equipped with a motor.

  In the first embodiment, the digital signal generation circuit 113 includes the speed difference table and the phase correction table. However, the present invention is not limited to this, and the speed difference table and the phase correction table are stored. A separate memory may be provided.

  In the second embodiment, the digital output signal obtained by A / D converting the analog output signal of the charge pump circuit 202 by the A / D conversion circuit 204 is compared with the digital output signal of the digital signal generation circuit 113, and both signals are compared. However, the present invention is not limited to this. However, the present invention is not limited to this, and the analog output signal of the charge pump circuit 202 and the D / A conversion circuit 114 are not switched. The analog output signal may be compared, and if the potential difference between the two signals is greater than or equal to a predetermined level, the signal switching by the analog selector 201 may not be performed.

  Further, when the potential difference between the analog output signal of the charge pump circuit 202 and the analog output signal of the D / A conversion circuit 114 is greater than or equal to a predetermined level at the signal switching timing by the analog selector 201, the analog output signal level of the charge pump circuit 202 is set. The digital signal generation circuit 113 may be controlled to bring the analog output signal level of the D / A conversion circuit 114 closer.

  Also, when the potential difference between the analog output signal of the charge pump circuit 202 and the analog output signal of the D / A conversion circuit 114 is greater than or equal to a predetermined level at the signal switching timing by the analog selector 201, the analog output signal of the D / A conversion circuit 114 The acceleration / deceleration signal generation circuit 203 may be controlled so that the analog output signal level of the charge pump circuit 202 approaches the level.

  Further, when the potential difference between the analog output signal of the charge pump circuit 202 and the analog output signal of the D / A conversion circuit 114 is equal to or higher than a predetermined level at the signal switching timing by the analog selector 201, digital signal generation is performed so as to eliminate the level difference. The circuit 113 and the acceleration / deceleration signal generation circuit 203 may be controlled.

  The present invention is achieved by supplying a software program (flowchart in FIG. 8) that realizes the functions of the above-described embodiments to a computer or CPU, and reading and executing the supplied program by the computer or CPU. can do.

  In this case, the program is directly supplied from a storage medium storing the program, or downloaded from another computer or database (not shown) connected to the Internet, a commercial network, a local area network, or the like. Supplied.

  The form of the program may be in the form of object code, program code executed by an interpreter, script data supplied to an OS (operating system), and the like.

  The present invention also supplies a computer or CPU with a storage medium storing a software program that implements the functions of the above-described embodiments, and the computer or CPU reads and executes the program stored in the storage medium. Can also be achieved.

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

  As a storage medium for storing the program code, for example, ROM, RAM, NV-RAM, floppy (registered trademark) disk, hard disk, optical disk (registered trademark), magneto-optical disk, CD-ROM, MO, CD-R, CD -RW, DVD-ROM, DVD-RAM, DVD-RW, DVD + RW, magnetic tape, nonvolatile memory card, etc.

  The function of the above-described embodiment is not only by executing the program code read from the computer, but the OS or the like running on the computer performs part or all of the actual processing based on the instruction of the program code. Can also be realized.

It is a block diagram which shows the structure of the DC brushless motor and control system which concern on the 1st Embodiment of this invention. 1 is a configuration diagram illustrating an internal structure of an image forming apparatus. It is the schematic which shows the structure of the exposure apparatus of an image forming apparatus. It is the figure which graphed the table for speed differences of a digital signal generation circuit. It is a figure which shows the PWM waveform generation example of a pulse width modulation circuit, (a) is a figure which shows a basic triangular wave, (b) is a figure which shows an output waveform. It is a figure which shows the timing of BD signal and Ref_BD signal. FIG. 6 is a graph of a phase correction table of a digital signal generation circuit. It is a flowchart which shows the flow of control of DC brushless motor. It is a block diagram which shows the structure of the DC brushless motor and control system which concern on the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the DC brushless motor and control system which concern on the 3rd Embodiment of this invention. It is a block diagram which shows the detailed structure of a digital PWM circuit. It is a figure which shows the PWM waveform with respect to a counter value. It is a block diagram which shows the structure of the DC brushless motor and control system which concern on a prior art example. It is a block diagram which shows the structure of the DC brushless motor and control system which concern on another prior art example.

Explanation of symbols

36 ITOP sensor 105 BD sensor 110 System control circuit 111 Target rotation speed setting circuit 112 Difference detection circuit 113 Digital signal generation circuit 114 D / A conversion circuit 115 Pulse width modulation circuit 116 Drive circuit 117 DC brushless motor 118 Rotation speed detection circuit 119 Amplifier 120 ref_BD generation / phase difference detection circuit 201 analog selector 202 charge pump circuit 203 acceleration / deceleration signal generation circuit 205 comparison circuit 250 digital PWM circuit

Claims (19)

In a motor control device that drives the motor based on a phase excitation signal and a drive control signal corresponding to the detected rotational speed of the motor,
Difference detection means for detecting a difference between the detected rotation speed and the target rotation speed, digital signal generation means for generating a digital signal corresponding to the difference, conversion means for converting the digital signal into an analog signal, and the analog signal And a drive control means for generating the drive control signal having a pulse width according to the motor control device.   The digital signal generation means generates a digital signal so that when the motor is started up, if the detected rotational speed is lower than the target rotational speed, the driving force for the motor is increased. 2. The motor control device according to claim 1, wherein when the detected rotational speed is higher than the rotational speed, the digital signal is generated so that the driving force for the motor is reduced. In a motor control device that drives the motor based on a phase excitation signal and a drive control signal corresponding to the detected rotational speed of the motor,
A difference detecting means for detecting a difference between the detected rotational speed and the target rotational speed; a digital signal generating means for generating a digital signal corresponding to the difference; and a converting means for converting the digital signal into a first analog signal; Acceleration / deceleration signal generation means for generating an acceleration signal or deceleration signal according to the difference, output means for outputting a second analog signal according to the acceleration signal or the deceleration signal, and the motor according to the driving status of the motor Selecting means for selecting the first or second analog signal; and drive control means for generating the drive control signal having a pulse width corresponding to the selected first or second analog signal. A motor control device.   4. The motor according to claim 3, wherein the selection means selects the first analog signal when shifting the motor, and selects the second analog signal when rotating the motor constantly. Control device.   4. The motor control apparatus according to claim 3, further comprising control means for controlling not to perform signal switching by the selection means when a potential difference between the first and second analog signals is equal to or greater than a predetermined level.   When the potential difference between the first and second analog signals is greater than or equal to a predetermined level, the control means causes the acceleration / deceleration signal generation means to bring the second analog signal level closer to the first analog signal level. 6. The motor control device according to claim 5, wherein the motor control device is controlled.   The control means controls the digital signal generation means to bring the first analog signal level closer to the second analog signal level when a potential difference between the first and second analog signals is equal to or higher than a predetermined level. The motor control device according to claim 5, wherein   The control means controls the digital signal generation means and the acceleration / deceleration signal generation means so as to eliminate the level difference when the potential difference between the first and second analog signals is equal to or greater than a predetermined level. The motor control device according to claim 5. In a motor control device that drives the motor based on a phase excitation signal and a drive control signal corresponding to the detected rotational speed of the motor,
A motor control apparatus comprising: difference detection means for detecting a difference between a detected rotation speed and a target rotation speed; and drive control means for generating the drive control signal having a pulse width corresponding to the difference.   The drive control means generates a drive control signal so that when the motor is started up, if the detected rotational speed is lower than the target rotational speed, the driving force with respect to the motor is increased. The motor control device according to claim 9, wherein when the detected rotational speed is higher than the rotational speed, the drive control signal is generated so that the driving force with respect to the motor is reduced.   A plurality of drive means for driving the motor; a drive means to be operated from the plurality of drive means is selected based on the phase excitation signal; and a driving force of the selected drive means is controlled based on the drive control signal. The motor control device according to claim 1, wherein:   10. The motor control device according to claim 1, wherein the motor is a DC brushless motor.   The motor control device according to claim 1, wherein the rotation speed of the motor is detected by a hall element or a rotary encoder. In a motor control method for driving the motor based on a phase excitation signal and a drive control signal corresponding to the detected rotational speed of the motor,
A difference between the detected rotation speed and the target rotation speed is detected, a digital signal corresponding to the difference is generated, the digital signal is converted into an analog signal, and the drive control signal having a pulse width corresponding to the analog signal is The motor control method characterized by producing | generating. In a motor control method for driving the motor based on a phase excitation signal and a drive control signal corresponding to the detected rotational speed of the motor,
The difference between the detected rotation speed and the target rotation speed is detected, a digital signal corresponding to the difference is generated, the digital signal is converted into a first analog signal, and an acceleration signal or a deceleration signal corresponding to the difference is generated And outputting a second analog signal corresponding to the acceleration signal or the deceleration signal, selecting the first or second analog signal according to the driving state of the motor, and selecting the selected first or A motor control method comprising generating the drive control signal having a pulse width corresponding to a second analog signal. In a motor control method for driving the motor based on a phase excitation signal and a drive control signal corresponding to the detected rotational speed of the motor,
A motor control method comprising: detecting a difference between a detected rotation speed and a target rotation speed, and generating the drive control signal having a pulse width corresponding to the difference. In a program for causing a computer to execute a motor control method for driving the motor based on a phase excitation signal and a drive control signal corresponding to a detected rotational speed of the motor,
A module for detecting a difference between a detected rotational speed and a target rotational speed; a module for generating a digital signal corresponding to the difference; a module for converting the digital signal into an analog signal; and a pulse width corresponding to the analog signal. And a module for generating the drive control signal. In a program for causing a computer to execute a motor control method for driving the motor based on a phase excitation signal and a drive control signal corresponding to a detected rotational speed of the motor,
A module for detecting a difference between a detected rotational speed and a target rotational speed; a module for generating a digital signal corresponding to the difference; a module for converting the digital signal into a first analog signal; and an acceleration corresponding to the difference A module for generating a signal or a deceleration signal, a module for outputting a second analog signal corresponding to the acceleration signal or the deceleration signal, and the first or second analog signal depending on the driving status of the motor And a module for generating the drive control signal having a pulse width corresponding to the selected first or second analog signal. In a program for causing a computer to execute a motor control method for driving the motor based on a phase excitation signal and a drive control signal corresponding to a detected rotational speed of the motor,
A program comprising: a module for detecting a difference between a detected rotation speed and a target rotation speed; and a module for generating the drive control signal having a pulse width corresponding to the difference.

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