JPS6134877Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a motor synchronous control device suitable for use in a turntable drive motor of a video disc player, a record player, and a capstan drive motor of a tape recorder.

2. Description of the Related Art Conventionally, there is a motor synchronous control device configured as shown in FIG. In FIG. 1, FG indicates a frequency generator connected to a motor M. A substantially sinusoidal alternating current signal is extracted from this frequency generator in accordance with the rotational speed of the motor M and is supplied to the rotational pulse generator 1. The alternating current signal is limited and rotation pulses corresponding to the rotation speed of the motor M are outputted from the rotation pulse generator 1. This rotation pulse is supplied as a trigger signal to a speed signal pulse generator 2 composed of a monostable multivibrator, and is also supplied to a phase comparator 3 as a comparison signal. The speed signal pulse generator 2 provides speed signal pulses with constant pulse intervals determined by the time constant of the monostable multivibrator. Phase comparator 3
Then, the phase of the rotational pulse is compared with a reference signal that serves as a reference for the rotational speed of the motor M, which is supplied from a reference signal generator 4 composed of a crystal oscillator or the like.
A phase pulse corresponding to the phase difference is obtained. The speed signal pulse is supplied to a pulse width/voltage converter 5, and a voltage corresponding to the pulse width of the speed signal pulse is obtained as an output of the pulse width/voltage converter. The above phase pulse is supplied to the pulse width/voltage converter 6, and a voltage corresponding to the pulse width of the above phase pulse is obtained as an output of the pulse width/voltage converter 6. Here, the output voltages of the pulse width/voltage converters 5 and 6 are added in analog form by an adder 7, and a DC amplifier 8
In addition, the current supplied from the DC amplifier causes the motor M to rotate synchronously so that the rotational speed becomes a predetermined rotational speed.

The above-mentioned motor synchronous control device has two pulse width/voltage converters 5 and 6, which has the disadvantage that the circuit configuration is complicated and expensive.

The purpose of this invention is to use one pulse width/voltage converter instead of the two pulse width/voltage converters described above to simplify a motor synchronous control device.

An embodiment of this invention will be described below with reference to FIGS. 2 and 3. FIG. 2 is a circuit configuration diagram of the motor synchronous control device, and FIG. 3 is a waveform diagram of each part of FIG. 2. FIG. 3A shows a waveform when the motor is rotating synchronously at a predetermined rotation speed. Figure 3 B is motor M
shows a waveform diagram when the rotation speed becomes lower than a predetermined rotation speed during synchronous rotation. FIG. 3C shows a waveform diagram when the rotation speed of the motor M becomes higher than a predetermined rotation speed during synchronous rotation.

In FIG. 2, the same parts as in FIG. 1 are given the same reference numerals and will be explained. A substantially sinusoidal alternating current signal is extracted from a frequency generator FG connected to the motor M in accordance with the rotational speed of the motor M, and is supplied to the rotational pulse generator 1. The rotation pulse generator ₂ outputs a rotation pulse S2 shown in FIG. The signal is supplied to the phase comparator 3 as a signal. The output of the speed signal pulse generator 2 is a constant speed signal pulse with a pulse interval t ₁ as shown in FIG. 3C.
_S3 is obtained. Pulse width of this speed signal pulse _S3
t ₂ becomes wider as the speed of the motor M becomes faster, and becomes narrower as the speed of the motor M becomes slower. The phase comparator 3 outputs the phase shown in FIG _. 3 D as the phase difference between the reference signal S ₁ shown in FIG. A pulse S ₄ is obtained. The speed signal pulse _S3 is supplied to the base of the switching transistor Q1 of the pulse width/voltage converter 9, and the transistor Q1 is in an on state for a period of pulse width _t2 of the speed signal pulse _S3 , and the charging current from the power supply +B is Therefore, capacitor C1 becomes transistor Q
1. Charged through resistor R1. At the same time that the transistor Q1 is turned off, a phase pulse S4 is supplied from the phase comparator ₃ to the base of the switching transistor Q2, and the transistor Q2 is turned on for a period of pulse width _t3 of the phase pulse _S4 , and the capacitor C
The initial potential of 1 is discharged through resistor R2 and transistor Q2. In this way capacitor C1
By repeatedly maintaining charging and discharging, the output at the capacitor C1 becomes the control signal shown in Fig. 3E.
_S5 , which is supplied to the motor M via the DC amplifier 8, and the motor M rotates at a predetermined synchronous rotation speed when there is no load fluctuation on the motor M, as shown in FIG. 3A.

A case where the load on the motor M increases and the rotational speed of the motor becomes lower than a predetermined rotational speed while the motor M is rotating synchronously will be explained with reference to the waveform diagram shown in FIG. 3B. When the rotational speed of the motor M decreases, the phase of the rotation pulse S ₂ lags behind the phase synchronization position shown in FIG. ₃ A as shown in FIG. The pulse width becomes narrower than the pulse width t ₂ shown in FIG. 3A by the pulse width t ₄ shown in FIG. 3B. On the other hand, the pulse width t ₂ of the speed signal pulse S ₃ becomes wider as the rotation speed of the motor M decreases. Therefore, the capacitor C1 is charged according to the pulse width of the speed signal pulse _S3 , and discharged for _a period of the pulse width _t4 of the phase pulse S4.
Since the amount of charge is large and the amount of discharge is small, the control signal _S5 output from the capacitor C1 increases as shown in FIG. 3B. Therefore, the voltage applied to the motor M increases, the motor M is accelerated and its rotational speed increases, and the motor M is immediately returned to the predetermined synchronous rotational speed.

A case where the load on the motor M decreases and the rotational speed of the motor becomes higher than a predetermined rotational speed while the motor M is rotating synchronously will be explained with reference to the waveform diagram shown in FIG. 3C. When the rotation speed of the motor M increases, the phase of the rotation pulse S ₂ advances from the phase synchronization position shown in FIG. 3 A as shown in FIG. 3 C, and the phase difference between this rotation pulse S ₂ and the reference signal S ₁ The pulse width of the phase pulse S ₄ output from the phase comparator 3 is wider than the pulse width t ₃ when the motor M is rotating synchronously, as shown in FIG. _3C . On the other hand, the pulse width _t2 of the speed signal pulse _S3 becomes narrower as the rotational speed of the motor M increases. Therefore, the amount of charge in the capacitor C1 decreases, and since the capacitor C1 is discharged for a period of pulse width _t5 of the phase pulse _S4 , the amount of discharge is large, so that the control signal _S5 output from the capacitor C1 is falls as shown in Fig. 3 (c). Therefore, the voltage applied to motor M becomes low, and motor M
is decelerated to a low rotational speed, and immediately returns to a predetermined synchronous rotational speed.

Therefore, even if the load on the motor M fluctuates as described above, the rotational speed of the motor M can always be controlled to a predetermined synchronous rotational speed.

In addition, the speed signal pulse width S ₃ and phase pulse mentioned above
This can also be carried out by replacing _S4 with each other, and the above-described pulse width/voltage converter 9 may be configured to charge after discharging instead of discharging after charging as described above. . In this case, the polarity of the DC amplifier 8 described above may be taken into account and an inverting circuit may be provided at the front stage of the DC amplifier.

4A and 4B show other embodiments of the pulse width/voltage converter. In FIG. 4A, a charging circuit is composed of a transistor Q3, a resistor R3, and a capacitor C2, and a discharging circuit is composed of a capacitor C2, a resistor R4, and a transistor Q4. Figure 4B
are resistor R5, transistor Q5, capacitor C3
A constant current charging circuit is constructed by the capacitor C3, a transistor Q6, and a resistor R6, and a constant current discharging circuit is constructed by the capacitor C3, the transistor Q6, and the resistor R6.

As mentioned above, this idea uses speed signal pulses with a constant pulse interval obtained according to the rotational speed of the motor, and phase pulses obtained from the phase difference between the rotational pulses corresponding to the rotational speed of the motor and a reference signal. By charging and discharging the capacitor of the pulse width/voltage converter, which consists of a capacitor charging and discharging circuit, the motor rotation speed is controlled by the terminal voltage of this capacitor, so the load on the motor fluctuates. However, the motor can always be rotated at a predetermined rotation speed, and the motor synchronous control device can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional motor synchronous control device, FIG. 2 is a circuit diagram of a motor synchronous control device showing an embodiment of this invention, and FIG. 3 is a waveform diagram of each part of FIG. FIG. 4 is a circuit diagram showing another embodiment of the pulse width/voltage converter. M...Motor, FG...Frequency generator, 1...Rotation pulse generator, 2...Speed signal pulse generator, 3...Phase comparator, 4...Reference signal generator, 9...Pulse width/
Voltage converter, C1...capacitor.

Claims (1)

[Scope of utility model registration request] A rotation pulse generator that processes signals from a frequency generator connected to the rotation shaft of the motor to generate rotation pulses according to the rotation speed of the motor, and a rotation pulse generator that generates speed signal pulses at regular intervals according to the rotation pulses. a speed signal pulse generator that generates a speed signal; a phase comparator that generates a phase pulse by comparing the phases of the rotation pulse and a reference signal from the reference signal generator;
When the capacitor is charged by the speed signal pulse, the capacitor is discharged by the phase pulse to obtain a control voltage, and when the capacitor is discharged by the speed signal pulse, the capacitor is charged by the phase pulse to obtain the control voltage. A synchronous control device for a motor that is equipped with a pulse width/voltage converter and uses this control voltage to control the rotational speed of the motor.