JPH033475B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a control circuit for a motor used in a record player or the like.

Conventional configuration and its problems Motors used in record players and the like generally need to rotate at a constant speed, and the speed is controlled. FIG. 1 shows a conventional example of the control circuit. The rotation signal of the motor 10 is generated by the frequency generator 1
1. It is detected as an FG pulse by the amplifier circuit 12 and the differentiation circuit 13, and is applied to the terminal 1b of the control circuit 1. Terminal 2 is provided to set the rotation speed, and if the period T ₁ of the FG pulse is greater than the reference time T ₀ , that is, the rotation speed is slow, the terminal 1d of the control circuit 1 goes high between T ₁ and T ₀ . level, transistor 4 turns on and sinks current through resistor 5,
Normal rotation torque is applied to the motor 10 through the inverting amplifier 8. Conversely, if T ₁ < T ₀ , transistor 3 is turned on during T ₀ - T ₁ and current flows out, causing motor 1
Apply reverse torque to 0. For example, the power supply voltage
Vcc, the values of resistors 5 and 7 are R ₅ and R ₇ respectively, and the reference voltage from power supply 9 is Vcc/2, motor 1
The voltage V _M across 0 is given by the following formula. In addition,
Capacitor 6 is provided to smooth the motor voltage.

V _M = R ₇ /R ₅・Vcc/2・T ₁ −T ₀ /T ₁ …… In other words, the motor voltage that balances the load torque
The motor 10 will rotate with a period _T1 that produces V _M. However, such a conventional circuit has a problem in that the rotational speed varies greatly depending on the load.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks, and an object thereof is to provide a motor control circuit that can reduce deviations in rotational speed due to load.

Structure of the Invention In order to achieve the above object, a motor control circuit of the present invention includes a waveform shaping circuit that shapes an FG signal from a frequency generator of a motor into pulses, and a period T ₁ of the FG pulse output from this waveform shaping circuit. and reference time
an output means that compares _T0 and outputs a voltage proportional to the difference or a pulse having an equivalent duty ratio; an up-down counter; and a latch circuit that latches the output of each stage of the up-down counter. Equipped with a D/A converter that converts the output of this latch circuit _into analog,
>T ₀ , the up-down counter is counted up by the first reference clock during T ₁ - _{T 0} , and when T ₀ > T ₁ , the up-down counter is counted up during T ₀ - _{T 1} . The counter is counted down, this count value is latched with the second reference clock by the latch circuit, this is converted into an analog quantity by the D/A converter, and this analog quantity and the output of the output means are combined. The configuration is such that the motor is controlled depending on the amount.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a circuit diagram showing an embodiment of the present invention, in which the same components as those shown in FIG. 1 are given the same reference numerals and their explanations will be omitted. The acceleration output and deceleration output of the control circuit 1 are provided by an AND gate circuit 15,
16, and a clock signal from terminal 20 is applied to the other input. The outputs of gate circuits 15 and 16 are up-down counter 1
The output of each stage of the up-down counter 17 is latched by a latch circuit 18 at every cycle of the FG pulse. The output of the latch circuit 18 is D/
It is converted into a current by the A converter 19 and added to the input of the inverting amplifier 8. That is, when the period T ₁ of the FG pulse is longer than the reference time T ₀ as shown in FIG. 3, the gate circuit 16 is opened for a period of T ₁ >T ₀ and the up/down counter 17 is counted up by the clock. This operation is repeated as long as T ₁ -T ₀ , and the sink current Ic of the D/A converter 19 continues to increase and is added to the acceleration pulse from the transistor 4. That is, the voltage V _M across the motor 10 is V _M = R ₇ /R ₅・Vcc/2・T ₁ −T ₀ /T ₁ +K 〓 ⁿ (Tn−To)... Here, K is the D/A converter. It is a conversion coefficient of 19 mag. As long as T ₁ > T ₀ , the second term on the right side of the above equation continues to increase, and its value corresponds to the load.
When V _M is equal to T ₁ = T ₀ , it rotates at a constant speed. If T ₁ <T ₀ , the up-down counter 17 counts down during the period of T ₀ -T ₁ and Ic becomes smaller (the number may change depending on the case), but the basic operation is the same.

Note that 14 is an inverter. In addition, FIG. 3 is a waveform diagram of each part of the circuit shown in FIG. 2, where a is a reference signal,
b is the FG pulse, c is the deceleration signal output from the terminal Ic of the control circuit 1, d is the acceleration signal output from the terminal 1d of the control circuit 1, and e is the D/A converter output current Ic.

Effects of the Invention As explained above, according to the present invention, T ₁ > T ₀
In the case of T ₁ - _{T 0} , the up-down counter is counted up with the first reference clock, and T ₀
> T ₁ , the up-down counter counts down during T ₀ - _{T 1} , the count value is latched by the second reference clock, converted to an analog quantity by the D/A converter, and output from this. Since the motor is controlled by the amount obtained by combining the outputs of the means, it is possible to realize motor control without direct current fluctuations in the rotational speed due to the load.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a conventional circuit, Fig. 2 is a circuit diagram of a motor control circuit in an embodiment of the present invention, and Fig. 3 is a circuit diagram of a motor control circuit according to an embodiment of the present invention.
The figure is a signal waveform diagram of each part of the motor control circuit when T ₁ >T ₀ . 1...Control circuit, 2...Rotation speed setting terminal, 3, 4...
Transistor, 5, 7...Resistor, 6...Capacitor,
8... Drive amplifier, 9... Power supply, 10... Motor, 11
...Frequency generator, 12...FG amplifier, 13...Differential circuit, 14...Inverter, 15, 16...AND gate, 17...Up-down counter, 18...Latch circuit, 19...D/A converter, 20...Reference clock input terminal .

Claims (1)

[Claims] 1. A waveform shaping circuit that shapes the FG signal from the motor frequency generator into pulses, and the period T ₁ and reference time T ₀ of the FG pulse output from this waveform shaping circuit.
an up-down counter, a latch circuit that latches the output of each stage of the up-down counter, and a latch circuit that latches the output of each stage of the up-down counter. Equipped with a D/A converter that converts the output of the circuit into an analog quantity, T ₁ >
In the case of T ₀ , the up-down counter is counted up with the first reference clock during T ₁ - _{T 0} , and in the case of T ₀ > T ₁ , the up-down counter is counted up between T ₀ - T ₁ . is counted down, this count value is latched with the second reference clock by the latch circuit, this is converted into an analog quantity by the D/A converter, and this analog quantity and the output of the output means are combined. A motor control circuit configured to control the motor based on the amount of the motor.