JPH11235070A - Motor driving controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a low cost motor driving controller which enables the stable rotation of a motor. SOLUTION: The phase and frequency of a speed detection signal fm whose frequency is multiplied by 1/N by a variable frequency divider 86 are compared with the phase and frequency of a reference clock signal fd , whose frequency is multiplied by 1/M by a variable frequency divider 84 by a speed comparing means 72. A differential speed signal Φp generated in accordance with the comparison results. A stator coil current Im which drives a motor unit 78 to turn is generated by a phase correcting means 74 and a rotation driving means 76 in accordance with the differential speed signal Φp . At that time, the values M and N are changed by a frequency division changer 88, so as to have a ratio of the frequencies of the respective output signals of the variable frequency dividers 84 and 86 constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a motor drive control device, and more particularly to a motor drive control device used for drive control of a motor requiring stable rotation.

[0002]

2. Description of the Related Art Generally, in an image recording apparatus or the like for recording an image by scanning a recording medium with a light beam modulated by an image signal, a plurality of reflecting mirror surfaces are provided on the outer periphery as means for deflecting the light beam. The rotating polygon mirror provided is rotated at high speed using a small motor, and a predetermined position of the reflecting mirror surface of the rotating polygon mirror is irradiated with a light beam, so that the incident angle of the light beam with respect to the reflecting mirror surface changes over time. In general, the direction of reflection of the light beam by the reflecting mirror surface is changed.

In a small motor for rotating the rotary polygon mirror at a high speed, a direct drive system in which the rotary polygon mirror is directly attached to a rotating shaft of the small motor is often employed, and a rotation speed is maintained constant. It has a motor drive control device.

Next, a configuration of a conventional motor drive control device will be described with reference to FIG. As shown in the figure, the motor drive control device comprises a reference clock generating means 70 for generating and outputting a reference clock signal f _o as the reference of the rotational speed of the motor, the reference of the reference clock generating means 70 output terminal for outputting a clock signal f _o is connected to one input terminal of the speed comparison means 72 for outputting a speed difference signal [Phi _p corresponding to the frequency difference, or phase difference between two input signals.

The speed difference signal Φ _p of the speed comparing means 72
Output terminal for outputting a is connected to the input terminal of the phase correction means 74 for generating and outputting a current control signal V _m based on the speed difference signal [Phi _p, the current control signal of the phase correction means 74 V
output terminal for outputting the _m is connected to the input end of the rotary drive means 76 for generating and outputting a stator coil current I _m for rotating the motor based on the current control signal V _m, the rotation driving means 76 output terminal for outputting the stator coil current I _m is connected to the motor unit 78.

On the other hand, the motor drive control device has a rotation speed detecting means 80 for outputting a speed detection signal f _m having a frequency corresponding to the rotational speed of the motor unit 78, the speed detection signal of the rotational speed detector 80 output terminal for outputting a f _m is connected to the other input terminal of the speed comparison means 72.

[0007] In such a motor drive control apparatus constructed as above, when the motor unit 78 is rotated, the rotation speed detecting means 80, speed comparison means the speed detection signal f _m having a frequency proportional to the rotational speed of the rotary body 72 is output. The speed detection signal f _m is compared with the reference clock signal f _o by the speed comparing unit 72, and outputs the frequency difference, or the speed difference signal [Phi _p corresponding to the phase difference relative to the phase correction means 74.

[0008] in FIG. 6 (B), the reference clock signal f _o and speed detection signal f _m, a timing chart showing an example of the relationship between the speed difference signal [Phi _p is shown. As shown in the figure, the speed difference signal [Phi _p is the magnitude of the pulse width corresponding to the phase difference between the reference clock signal f _o and speed detection signal f _m, and the pulse interval of the pulse interval reference clock signal f _o It has the same size.

The speed difference signal Φ _p passes through the phase correcting means 74 and becomes a current control signal V _m to be output to the rotation driving means 76. The rotary drive means 76, based on the magnitude of the input current control signal V _m, to control the current value of the stator coil current I _m that rotates the rotating member of the motor unit 78.

[0010] Here, if, when the frequency of the speed detection signal f _m is lower than the frequency of the reference clock signal f _o is,
Speed difference signal [Phi _p output from the speed comparing unit 72 increases, as a result, the rotary drive means 76 increases the stator coil current I _m, the rotation of the rotating body of the motor unit 78 is accelerated. On the other hand, on the other hand, the speed detection signal f
If the frequency _m is higher than the frequency of the reference clock signal f _o, the stator coil current I _m is reduced, the rotation of the rotating body of the motor unit 78 is decelerated. That is, the rotation speed of the rotating body of the motor unit 78 always converges to a constant value.

According to the servo control theory, it is generally known that the signal response characteristics of the system must satisfy a predetermined condition in order to actually obtain the above-mentioned constant speed operation. If the signal response characteristics of the system do not satisfy the above-described predetermined condition, problems such as the rotational speed continuing to fluctuate and the accuracy of the rotational speed being extremely poor occur. Therefore, usually, the above-mentioned predetermined condition is satisfied by providing the phase correction means 74 to correct the signal response characteristics of the system.

By the way, the performance required for a small motor used for rotating a rotary polygon mirror, for example, is to first maintain an accurate rotation speed, and secondly, to maintain a constant rotation speed from a stopped state. Time to reach
This means that the transition time when the rotation speed is changed is as short as possible. However, it is very difficult for both the first and second required performances to be maximized. This is because the optimum signal response characteristics differ from one another, and if one of them is set to the optimum state, the performance of the other is sacrificed.

Therefore, focusing on the fact that the situations where the first and second required performances are required are different from each other, the circuit configuration is operated so that the performance required for each operating condition of the motor is optimized. A method of switching according to the situation has been considered. That is, a circuit is used that immediately shifts to the set rotation speed immediately after turning on the power, and after the set rotation speed is reached, the circuit is switched to a circuit that maintains the rotation speed constant with very high accuracy. is there.

FIG. 7A shows an example of a circuit configuration of a motor drive control device for realizing such a method. The phase correction means 74 in the circuit configuration shown in FIG. Te, the motor unit 78 a current control signal V _m
Switch unit 8 for changing according to the operation status of
2 is added.

[0015] Further, the motor drive control device is a DSP (Di
There is also a method realized by a digital processing circuit such as a digital signal processor, and switching signal response characteristics by a program.

[0016]

However, the method for switching the circuit configuration has a problem that the behavior of the circuit tends to be unstable when the circuit configuration is switched.

That is, for example, when the circuit configuration is as shown in FIG. 7A, as shown in the timing chart of FIG.
At the moment when 1) is turned on, the current control signal V _m
Ends up greatly vibrate, this resulting in rotation of the rotating body of the stator coil current I _m is vibrated motor unit 78 is becoming unstable.

Further, in the method in which the motor drive control device is realized by a digital processing circuit and the signal response characteristics are switched by a program, there is a problem that the circuit cost increases drastically.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide an inexpensive motor drive control device capable of stably rotating a motor.

[0020]

According to a first aspect of the present invention, there is provided a motor drive control device for converting a frequency of a reference clock signal, which is a reference of a rotation speed of a motor, according to a set conversion magnification. Reference clock conversion means for performing
A rotation speed detection unit that detects a rotation speed of the motor and generates a speed detection signal having a frequency corresponding to the rotation speed, and a speed signal conversion unit that converts the frequency of the speed detection signal according to a set conversion magnification. The reference clock converter and the speed signal converter so that the frequency ratio between the reference clock signal whose frequency is converted by the reference clock converter and the speed detection signal whose frequency is converted by the speed signal converter is constant. Magnification changing means for respectively changing the conversion magnification of the means; and a phase and / or frequency of a reference clock signal whose frequency is converted by the reference clock converting means and a speed detection signal whose frequency is converted by the speed signal converting means. By comparison,
Speed comparison means for generating a speed difference signal indicating a speed difference between the set rotation speed and the actual rotation speed of the motor, and an actual speed of the motor based on the speed difference signal generated by the speed comparison means. When the rotation speed is lower than a set rotation speed, the power supply to the motor is increased, and when the rotation speed is higher, the power supply is reduced or braked. Means.

According to the motor drive control device of the first aspect, the frequency of the reference clock signal, which is the reference of the rotation speed of the motor, is converted by the reference clock conversion means in accordance with the set conversion magnification. The frequency of the speed detection signal having a frequency corresponding to the rotation speed of the motor generated by the rotation speed detection means is converted by the signal conversion means in accordance with the set conversion magnification.

Further, the speed comparison means compares the phase and / or frequency of the reference clock signal whose frequency has been converted by the reference clock conversion means with the speed detection signal whose frequency has been converted by the speed signal conversion means. A speed difference signal indicating a speed difference between the set rotation speed of the motor and the actual rotation speed is generated, and the actual power of the motor is determined by the driving power supply unit based on the speed difference signal generated by the speed comparison unit. When the rotation speed is lower than the set rotation speed, the power supplied to the motor is increased, and when the rotation speed is higher, the supplied power is reduced or the brake is applied.

At this time, the reference clock conversion means and the speed signal are controlled so that the frequency ratio between the reference clock signal whose frequency has been converted by the reference clock conversion means and the speed detection signal whose frequency has been converted by the speed signal conversion means is constant. The conversion magnification of the conversion means is changed by the magnification changing means. Therefore, from the state where the motor is stopped to the state where the motor starts rotating and reaches the desired rotational speed, the state where the motor is rotating from a state where the motor is rotating at a constant speed to another rotational speed, the state where the motor is at a constant speed The signal response characteristic can be changed by changing the conversion magnifications of the reference clock conversion means and the speed signal conversion means according to each of a plurality of states such as a state from a rotating state to a stop state,
Optimal motor drive control can be performed for each rotation state.

As described above, according to the motor drive control device of the first aspect, since the signal response characteristic is changed without including the switching means such as the switch circuit in the control system, the rotational state is always stable. Can be obtained, and an expensive article such as a DSP is not used, so that the motor drive control device can be configured at low cost.

According to a second aspect of the present invention, there is provided the motor drive control device according to the first aspect, wherein each of the reference clock conversion means and the speed signal conversion means changes the conversion magnification of the reference clock conversion means and the speed signal conversion means. And the timing of changing the conversion magnification is controlled by an external signal input from an external device.

According to the motor drive control device of the second aspect, the change of the conversion magnification of each of the reference clock conversion means and the speed signal conversion means by the magnification change means by the external signal input from the external device, and the conversion magnification Is controlled.

Thus, according to the motor drive control device of the second aspect, the change of the conversion magnification of each of the reference clock conversion means and the speed signal conversion means by the magnification change means and the timing of the change of the conversion magnification are controlled by the external device. Since control can be performed by an input external signal, components required for the control can be omitted, and the motor drive control device can be configured at lower cost and in a smaller space.

[0028]

Embodiments of the present invention will be described below in detail with reference to the drawings.

[First Embodiment] In the first embodiment, an embodiment in which the motor drive control device according to the present invention is applied to an optical deflector of an image recording apparatus will be described. First, the configuration of the image recording apparatus according to the first embodiment will be described with reference to FIGS.

As shown in FIG. 1, this image recording apparatus comprises:
A laser light generator 10 for generating laser light;
In the direction in which the laser beam is emitted from the laser beam generator 10, a collimator lens 12 that collimates the laser beam and a rotating polygon mirror 16 having a plurality of (eight in FIG. 1) reflecting mirror surfaces 14 on the outer periphery are provided. The polygon mirror motors are arranged in order.

On the other hand, a condensing optical system 54 and a photoreceptor 56 as a recording medium are sequentially arranged in the direction in which the rotary polygon mirror 16 reflects the laser light.

Next, the structure of the rotary polygon mirror motor will be briefly described. As shown in the cutaway side view of FIG. 2, the rotary polygon mirror 16 is fixed to the outer periphery of a cylindrical rotary sleeve 18, and is rotatably held together with the rotary sleeve 18 around a fixed shaft 22.

The rotary sleeve 18 is provided with a rotary polygon mirror fixing spring 20, a mirror pedestal 26, a thrust bearing magnet 32, a drive magnet 33, and an FG magnet 34. A rotating body that can rotate integrally as a center is formed.

On the other hand, a magnetic body 36 is provided on the upper surface of the base 38 so as to face the side surface of the magnet 32 for the thrust bearing, and supports the rotating body so as to be substantially suspended in the axial direction. I have.

On the upper surface of the base 38, a drive control circuit board 40 having a coil unit 42 and a control unit 44 is provided with a driving magnet 33 and a plurality of stator coils 46 provided on the coil unit 42. Are installed so as to face each other in the axial direction. In addition, the motor drive control device of the present invention is embodied mainly by electronic components mounted on the drive control circuit board 40.

Further, with the stator coil 46 is installed in the coil unit portion 42, FG pattern 60 is formed, generating a speed detection signal f _m having a frequency proportional to the rotational speed of the rotary body I do.

Next, a circuit configuration of the control unit 44 on the drive control circuit board 40 will be described with reference to FIG. In FIG. 3, parts having the same functions as those of the conventional circuit configuration shown in FIG. 6 are denoted by the same reference numerals.

As shown in FIG. 3, the control unit 44 of the drive control circuit board 40 according to the first embodiment, the reference for generating and outputting a reference clock signal f _o as the reference of the rotational speed of the motor Clock generating means 70,
Reference output terminal for outputting a reference clock signal f _o of the clock generating means 70 is connected to one input terminal of the variable frequency divider 84 to the frequency of the reference clock signal f _o input 1 / M times and outputs cage, the output end of the variable frequency divider 84 is connected to one input terminal of the speed comparison means 72 outputs the frequency difference between two signals inputted, or the speed difference signal [Phi _p corresponding to the phase difference.

The speed difference signal Φ _p of the speed comparing means 72
Output terminal for outputting a is connected to the input terminal of the phase correction means 74 for generating and outputting a current control signal V _m based on the speed difference signal [Phi _p, the current control signal of the phase correction means 74 V
rotary drive means for generating and outputting a stator coil current I _m on the basis of the output end to the current control signal V _m for outputting the _m 7
Is connected to the input terminal 6, an output terminal for outputting the stator coil current I _m of the rotation driving means 76 is rotating member except the rotating polygon mirror 16 in FIG. 2, is constituted by a fixed shaft 22, and the stator coil 46 Connected to the stator coil 46 of the motor unit 78.

On the other hand, outputs the speed detection signal f _m a rate having a frequency proportional to the rotational speed detection signal rotation speed detecting means 80 which is constituted by the FG pattern 60 for outputting a f _m of the rotator of the motor unit 78 output is connected to one input terminal of the variable frequency divider 86 and outputs the 1 / N times the frequency of the speed detection signal f _m that is input, the output end of the variable frequency divider 86 is the speed comparison It is connected to the other input of the means 72. Therefore, in the speed comparison means 72,
A speed difference signal Φ _p corresponding to the frequency difference or the phase difference between the signal input from the variable frequency divider 84 and the signal input from the variable frequency divider 86 is output to the phase correction means 74.

The variable frequency divider 84 and the variable frequency divider 86
Are connected to the output terminals of the frequency dividing number switch 88 for outputting the frequency dividing number switching signal A and the frequency dividing number switching signal B, respectively. The value of N of the variable frequency divider 86 is set by the frequency division number switching signal A and the frequency division number switching signal B generated based on the state of the gain changeover switch 90 connected to the frequency division number switch 88. You.

It should be noted that the variable frequency divider 84 serves as the reference clock converting means of the present invention, and the variable frequency divider 86 serves as the speed signal converting means of the present invention.
0 corresponds to the magnification changing means of the present invention, and the phase correction means 74 and the rotation driving means 76 correspond to the driving power supply means of the present invention, respectively.

Next, the operation of the first embodiment will be described. First, the overall operation of the image recording apparatus configured as described above will be described.

In the image recording apparatus configured as described above, when an image is recorded on the photoreceptor 56, first, the plurality of stator coils 46 are driven by supplying alternating currents having phases shifted from each other. A repulsive force and an attractive force are generated between the magnet 33 for use and the stator coil 46 to rotate the rotating body at a predetermined rotational speed in the direction of arrow A in FIG.

After the rotation of the rotator is started, a laser light modulated by an image signal is emitted from the laser light generator 10 (see FIG. 1). The laser light emitted from the laser light generator 10 enters the reflecting mirror surface 14 of the rotary polygon mirror 16 via the collimator lens 12, is reflected by the reflecting mirror surface 14, and is condensed by the photoreceptor 56 via the condensing optical system 54. Is projected to
At this time, since the rotary polygon mirror 16 is rotating in the direction of arrow A in FIG. 1, the laser light is gradually deflected in the reflection direction, and scans the photosensitive member 56 in the main direction. When the main scanning for one line is completed, the sub-scanning is performed by rotating the photosensitive member 56 by one line pitch in the direction of arrow B in FIG. By repeating the main scanning and sub-scanning the number of times corresponding to the number of lines of one image, an image (latent image) for one image is recorded on the photoconductor 56.

Next, the control unit section 44 in the drive control circuit board 40 corresponding to the motor drive control device of the present invention.
The operation of will be described. When the rotating body of the motor unit 78 (see FIG. 3) rotates, the rotation speed detecting means 80 detects a speed detection signal f _m having a frequency proportional to the rotation speed.
Is generated. After the frequency of the speed detection signal f _m is which is 1 / N times the variable frequency divider 86, the signal f _r is input to one input terminal of the speed comparison means 72. On the other hand, a reference clock signal f _o (signal f _c ) which is input to the variable frequency divider 84 and whose frequency is multiplied by 1 / M is input to the other input terminal of the speed comparison means 72.

The speed detection signal f _m and the frequency which the frequency is 1 / N times that on the basis of the 1 / M multiplied by the reference clock signal f _o, the internal speed comparison means 72 and the frequency difference of each signal The phase difference is detected, and a speed difference signal Φ _p indicating the level of the phase difference or the advance or delay is generated. In the first embodiment, when both the pulse width and the pulse interval of the speed difference signal Φ _p do not change, it indicates that the frequencies of the two input signals are completely the same.

The speed difference signal Φ_pEnters the phase correction means 74.
After being converted from a pulse train to a DC signal, the phase,
The signal characteristics such as gain are adjusted and the current control signal V_mage
And output to the rotation driving means 76. With the rotation driving means 76
Is the input current control signal V _mBased on the size of
Stator coil current I flowing through_mCurrent value
Is controlled, and the rotating body of the motor unit 78 is
The control of the current switching logic is the same so that it always rotates.
Sometimes done.

[0049] Here, the speed detection signal f _m to 1 / N times the frequency dividing signal f frequency reference clock signal f _o of _r 1 /
Becomes lower than the frequency of the divided signal f _c M times, the pulse width of the speed difference signal [Phi _p becomes narrower than usual, the frequency of the signal f _r obtained by dividing the speed detection signal f _m to 1 / N times the reverse There if it becomes higher than the frequency of the reference clock signal f _o to 1 / M times the divided signal f _c, the pulse width of the speed difference signal [Phi _p becomes wider.

Such a speed difference signal Φ_pLarge pulse width
The small value is converted to a voltage value by the next-stage phase correction means 74.
The stator coil voltage input to the motor unit 78
Style I _mOf the motor unit 78
When the rotation speed of the rotating body decreases, the rotation of the rotating body accelerates,
It works so that it becomes slower when it gets faster. Like this
Therefore, the rotation speed of the rotating body of the motor unit 78 is always constant.
Is held.

Next, the operation of changing the signal response characteristic of the control system in the first embodiment will be described. As described above, the variable frequency divider 84 and the variable frequency divider 86, each have a 1 / M times and 1 / N multiplying function each frequency of the reference clock signal f _o and speed detection signal f _m Yes,
At this time, each value of M and N is set to an arbitrary value according to an instruction from the frequency division number switch 88.

The timing chart of FIG.
the frequency division number of the variable frequency divider 84 to M 'from M by an instruction from the division number switch 88 in response to the switching signal S _f in _s,
This shows a case where the frequency dividing number of the variable frequency divider 86 is simultaneously changed from N to N ′.

Here, the division numbers M, N, M ', and N' have the following relationship. M '/ M = N' / N = C (C is an arbitrary constant) In this case, the frequency of the reference clock signal f _o signal f _c and the speed detection signal f _m having a frequency 1 / M times the frequency of the 1
/ When N times the frequency and phase of the signal f _r of frequency is an exact match, no rotational velocity is no change in the rotation of the motor unit 78 before and after the time t _s. This is because the speed comparison means 72 considers only the difference between the frequency and phase of the two signals to be compared, and does not consider the magnitude of each signal.

However, in an actual motor, a circuit
From the problem of accounting, the reference clock signal f_oAnd speed detection signal
No. f_mAnd the phase are shifted by a fixed amount.
It is often used in a state. The phase shift is the speed difference signal
Φ_pIs set to 360 degrees, and the speed difference signal Φ_pPal
It is expressed by how many times the width corresponds. Speed shown in FIG.
Difference signal Φ_pAt the time t_sPrevious phase difference was about 9
0 degrees but at time t _sAfter that, the division number changed
From the speed difference signal Φ_pPeriod increases, resulting in a phase difference
Is getting smaller. This time t_sPhase difference before and after
θ and θ ′ degrees, the phase difference between
There is a relationship.

[0055] θ '= θ / C That is, in the time before and after t _s, will be the phase difference is 1 / C times apparently, this is equivalent to the control loop gain is 1 / C times . Further, since the amount of change in the gain is determined purely by simply changing the frequency division number in accordance with the instruction of the frequency division number switch 88, the amount of change, timing, and the like can be set freely.

In general, the control loop gain of the control system and the signal response characteristic have a deep relationship, and especially in the case of a control system for controlling the rotation of a motor for rotating a rotary polygon mirror, the control loop gain should be increased. By doing so, it is possible to shorten the time from the stop state of the motor to the constant speed rotation, and conversely, by reducing the gain, it is possible to reduce rotation unevenness and maintain the rotation speed with high accuracy. Can be.

Therefore, in the first embodiment, the control loop gain is set to be high during the period from the stop of the rotating body of the motor unit 78 to the constant speed rotation so that the rotation speed can be quickly increased. Then, when the rotation speed approaches the set rotation speed, the gain is gradually changed by changing the frequency division number, and when the rotation speed finally becomes substantially constant, the gain is further set lower. Thus, stable rotation is performed.

As described in detail above, in the motor drive control device according to the first embodiment, the signal response characteristic is changed without including the switching means such as the switch circuit in the control system such as the phase correction means. Thus, a stable rotation state can be always obtained, and the motor drive control device can be configured at low cost because expensive articles such as a DSP are not used.

[Second Embodiment] Next, referring to FIG.
A second embodiment of the present invention will be described. FIG.
FIG. 4 is a configuration diagram showing a circuit configuration of a control unit section 44 in the drive control circuit board 40 according to the second embodiment;
Other configurations and operations are the same as those of the above-described first embodiment, and a description thereof will be omitted.

As shown in FIG. 5, the circuit configuration of the control unit 44 in the drive control circuit board 40 according to the second embodiment is different from that shown in FIG. , and differences that there is a frequency division number switching controller 89 the timing of the dividing number of changes and the change of the variable frequency divider by input from an external device (not shown) gain control signal S _f is controlled ing.

Therefore, in the motor drive control device according to the second embodiment, since the change and the timing of the change of the control loop gain can be controlled from the external device, the components required for this control can be omitted. In addition, the motor drive control device can be configured at lower cost and in a smaller space.

In each of the above embodiments, a case has been described in which the motor drive control device of the present invention is applied to drive and control a motor for rotating a rotary polygon mirror of an image recording apparatus. It is needless to say that the present invention can be applied to drive control of any motor.

[0063]

According to the motor drive control device of the first aspect, the signal response characteristic is changed without including a switching means such as a switch circuit in the control system, so that a stable rotational state is always maintained. Can be obtained,
Since an expensive article such as a DSP is not used, the effect that the motor drive control device can be configured at low cost can be obtained.

According to the motor drive control device of the second aspect, the change of the conversion magnification of each of the reference clock conversion means and the speed signal conversion means by the magnification change means and the timing of the change of the conversion magnification are input from the external device. Since the control can be performed by an external signal, the components required for the control can be omitted, and the motor drive control device can be configured at lower cost and in a smaller space.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a schematic configuration of an image recording apparatus according to a first embodiment.

FIG. 2 is a cutaway side view showing a schematic configuration of the rotary polygon mirror motor according to the first embodiment.

FIG. 3 is a block diagram illustrating a configuration of a control unit in the drive control circuit board according to the first embodiment.

FIG. 4 is a timing chart showing a state of each signal shown in FIG. 3;

FIG. 5 is a block diagram illustrating a configuration of a control unit in a drive control circuit board according to a second embodiment.

FIG. 6A is a block diagram showing a schematic configuration of a conventional motor drive control device, and FIG. 6B is a timing chart showing a state of each signal shown in FIG.

FIG. 7A is a block diagram showing another configuration of the conventional motor drive control device, and FIG. 7B is a timing chart showing the state of each signal shown in FIG.

[Explanation of symbols]

 Reference Signs List 16 rotary polygon mirror 40 drive control circuit board (motor drive control device) 70 reference clock generation means 72 speed comparison means 74 phase correction means (drive power supply means) 76 rotation drive means (drive power supply means) 78 motor unit 80 rotation speed Detecting means 84 Variable frequency divider (reference clock converting means) 86 Variable frequency divider (speed signal converting means) 88 Frequency dividing number switch (magnification changing means) 89 Frequency dividing number switching controller (magnification changing means) 90 Gain switching Switch (magnification changing means)

Claims (2)

[Claims] 1. A reference clock conversion means for converting a frequency of a reference clock signal, which is a reference of a rotation speed of a motor, according to a set conversion magnification, and a frequency corresponding to the rotation speed by detecting the rotation speed of the motor. A rotation speed detection unit that generates a speed detection signal of the above, a speed signal conversion unit that converts the frequency of the speed detection signal according to a set conversion magnification, and a reference clock signal whose frequency is converted by the reference clock conversion unit. Magnification changing means for respectively changing the conversion magnifications of the reference clock converting means and the speed signal converting means such that the frequency ratio between the reference clock converting means and the speed signal converting means becomes constant. A reference clock signal whose frequency has been converted by the clock conversion means and a speed detection whose frequency has been converted by the speed signal conversion means; Speed comparing means for generating a speed difference signal indicating the speed difference between the set rotation speed of the motor and the actual rotation speed by comparing the phase and / or frequency of the signal, Based on the speed difference signal, when the actual rotation speed of the motor is lower than a set rotation speed, the power supply to the motor is increased, and when the rotation speed is high, the supply power is reduced or a brake is applied. And a driving power supply unit for supplying power to the motor. 2. The method according to claim 1, wherein the change of the conversion ratio and the timing of the change of the conversion ratio of each of the reference clock conversion unit and the speed signal conversion unit are controlled by an external signal input from an external device. The motor drive control device as described in the above.