JPS5911792A - Drive control circuit for motor - Google Patents

Abstract

PURPOSE:To enable to finely control the speed of a motor by switching the value of a reference voltage at every half period to compare the voltage twice in one period. CONSTITUTION:The AC output A of a frequency generator 2 which is connected directly to the rotor of a motor 1 is converted by a waveform shaper 4 to a rectangular wave B. A differentiating circuit 5 conducts a transistor 6 at the rising edge of the rectangular wave B, thereby discharging the charge of the condenser 7 of a time constant circuit. Thus, a triangular wave voltage C of the period of the rectangular wave B is generated across the condenser 7. On the other hand, since the transistor 15 is turned ON and OFF at every half period of the rectangular wave B, the reference voltage D set by the dividing resistors 12, 13 or dividing resistors 12, 13, 14 is outputted. A voltage comparator 10 turns ON a drive transistor 11 during the period while the voltage C is higher than the reference voltage D.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a drive control circuit for a motor used in record players, tape recorders, and the like.

A conventional circuit of this type, which is an object of improvement of the present invention, will be explained with reference to FIG.

1 is an electric motor, 2 is a frequency generator directly connected to the rotor of the electric motor 1, and its AC output is amplified by an amplifier 5 and converted into a rectangular wave by a waveform shaper 4.

5 is a differentiating circuit, and at the rising υ edge of the rectangular wave, a transistor 6 is activated.
1, the charge in the capacitor 7 of the time constant circuit is discharged. The capacitor 7 is charged by the current source 8 while it is discharged at the rising edge of the next period of the square wave.
Its terminal voltage (0 point city; EF) is base Ji4', voltage 9
When the voltage at point D is higher, the comparator 10 detects the increased voltage and Tif, ! The electric motor 1 is driven by passing 2H through the transistor 11 connected to the power supply circuit of the IIIJ machine 1.

FIG. 2 shows voltage waveforms at various points in the circuit of FIG.

A is the output of the amplifier 5 (AC output), B is the output of the waveform shaper 4 (rectangular wave), C is the terminal voltage of the capacitor 7 (triangular wave), and D is a constant reference voltage. To is the time 1, ie, the reference time, until the terminal voltage 0 of the capacitor 7 becomes the same potential as the reference voltage determined by the specified speed of the motor. 1゛, TI, Tt...d - T, T, , T, and reference time T in the period of the output of the waveform shaper 4. The difference between ΔT and ΔT2... becomes the phase angle (time) for driving the electric @11+. E is the output voltage of the voltage comparator 1o, and the above Δ
The transistor 11 is made conductive between 1(, -) of T8, ΔT, and current is supplied to the motor 1.

By the way, since the above circuit uses a certain standard type soil, voltage comparison is performed once per cycle of frequency power generation (ac output), but in the present invention, this reference voltage is changed every half cycle. The purpose of this is to improve the speed control by eliminating the need to compare the voltage twice per cycle and to achieve more fine-grained speed control. The capacitor charged by the current source is discharged at the rising edge of the rectangular wave obtained by rectifying the alternating current output of the frequency generator until the capacitor is discharged at the rising edge of the next period of the rectangular wave. In the circuit that charges the current source to generate a triangular wave, compares the triangular wave with a reference voltage, and supplies current to the motor when the wave height is at a phase angle exceeding the reference voltage. This motor drive control circuit is characterized in that voltage comparison is performed twice within one cycle by switching the voltage value every half cycle of the phase angle of the rectangular wave.

An embodiment of the present invention will be described with reference to FIG.

In the same figure, among 1 to 11, the group l in Figure 1? The other parts except voltage 9 are the same as in FIG.

In the present invention, the reference voltage (2) is set by the voltage dividing resistors 12, 13, and 14. A transistor 15 is connected in parallel with the lowest stage voltage dividing resistor 14 among these six voltage dividing resistors, and this transistor 15 is connected to the output B of the waveform shaper 4.
Otherwise, the reference voltage is changed by making it conductive every half cycle.

In FIG. 4, A, B and C are A in FIG.

B and C are very different. In the present invention, the reference voltage changes every half period of the rectangular wave B.

T, TI, T is one period of the rectangular wave B, and the reference voltage is half the period 1/2T, 1/2T, , 1/2T
, it changes every time. T is the reference time determined by the period T of the square wave when the motor is at the reference speed. Then, in the period of TI s TI when the motor speed decreases, △
T, ten △direction, △T2+△T2' is the time to drive this motor, and the drive time △direction□, △T2' is better than the driving time △T1, △T in Fig. 2 (Fig. 4). E is the drive time of the motor, and the shaded part is the part increased from E in Fig. 2.
The speed of the electric motor recovers faster.

As described above, the present invention improves the conventional drive control circuit shown in Figure 1 to finely control the motor drive N, and as a result, vibrations are reduced, making it suitable for use in audio equipment, etc. It is extremely effective in some cases.

[Brief explanation of the drawing]

Figure 1: Conventional drive control circuit diagram Figure 2: Voltage waveform diagram at each point in Figure 1 Figure 6 - Drive control circuit diagram of the present invention Figure 4: Voltage waveform diagram at each point in Figure 5 Symbols] 1... Electric 1i1J machine, 2... Frequency generator, 6... Tank intermediate device, 4... Waveform shaper, 5... Differential circuit, 6.11.15, Transistor, 7 ...Capacitor, 8...Current source, 9...Reference 1
L pressure, 10...voltage comparison z((,12,15,14・
...Patent attorney representing partial pressure resistance Masanobu Shibasaki;, 1,..., 1 Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 4

Claims (1)

[Claims] At the rising edge of the rectangular wave obtained by rectifying the AC output of the frequency generator directly connected to the motor, the electric charge of the capacitor charged by the current source is discharged, and the capacitor is activated at the rising edge of the next period of the rectangular wave. Until it is discharged at the upper edge, it is charged by the current source and generates a triangular wave. In a circuit that compares the triangular wave with a reference t4 voltage and supplies current to a motor when the wave height is at a phase angle exceeding this reference voltage, the value of the reference voltage is changed every half period of the phase angle of the rectangular wave. A motor drive control circuit characterized in that voltage comparison is performed twice within one cycle by switching.