JPS586399B2 - Motor rotation speed adjustment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a motor rotation speed adjusting device that can stably adjust the rotation speed of a motor with simple operation and configuration.

Conventionally, when adjusting the rotation speed of a motor in a record player, etc., a phase control type motor that rotates in synchronization with a reference frequency or a speed control type motor that is controlled by a reference voltage is configured with an RC oscillator, etc. It is common practice to adjust the motor rotation speed by providing the output of a variable frequency oscillator, or the output of a variable reference voltage generator composed of a Zener diode and a variable resistor, and adjusting the output. there were.

However, with these conventional adjustment devices, it is difficult to maintain stable motor rotation because fluctuations in the output frequency of the RC oscillator and voltage fluctuations of the Zener diode directly affect motor rotation due to aging of components and changes in ambient temperature. To get R
It was necessary to add a complicated temperature compensation circuit to the C oscillator and Zener diode.

In order to alleviate such drawbacks, a motor rotation speed adjusting device as shown in FIG. 1 can be considered.

To explain this, in FIG. 1, 1 is a variable oscillation circuit composed of an RC oscillator, etc., and 2 is a device that detects the frequency difference or phase difference between the output frequency of the variable oscillation circuit 1 and the output frequency of the frequency subtraction circuit 5. 3 is a filter circuit for attenuating noise and ripple included in the output of phase comparison circuit 2; 4 is a voltage-controlled oscillator that changes the oscillation frequency according to the output of filter circuit 3; The frequency fo is subtracted from the reference frequency f8 by the frequency subtraction circuit 5 mentioned above, and its output is supplied to one input terminal of the phase comparison circuit 2.

The variable oscillation circuit 1, phase comparison circuit 2, filter circuit 3, voltage controlled oscillator 4, and frequency subtraction circuit 5 described above constitute a PLL (phase control loop).

6 is a frequency dividing circuit for frequency dividing the output of the voltage controlled oscillator 4, and 7 is a frequency controlled motor that rotates in proportion to the input frequency.

8 is a changeover switch, and when the movable contact C is connected to the fixed contact b side, the frequency control type motor 7 rotates in proportion to the reference frequency f8.

Further, when the movable contact C of the switch 8 is connected to the fixed contact a side, the frequency control type motor 7 operates at the output frequency f of the voltage control type oscillator 4.

rotates in proportion to. In the configuration shown in FIG. 1, if the output frequency of the variable oscillation circuit 1 is ft, then ft=fo-
f8 or f.

When the relationship -f8+ft is established, a synchronized state is achieved and stability is achieved.

At this time, if the movable contact C of the switch 8 is connected to the fixed contact a side, the output frequency ft of the variable oscillation circuit 1 can be varied.

Since the rotation speed of the motor 7 can also be changed, the rotation speed of the motor 7 can be changed accordingly.

However, in this case, when the movable contact C of the switch 8 is connected to the fixed contact b side (when the frequency is fixed), the frequency-controlled motor 7 rotates at a constant speed in proportion to the reference frequency f8, and the switch 8 When the movable contact C is connected to the fixed contact a side (in the case of variable frequency), it rotates in proportion to the frequency f8+ft, and the rotation speed can be adjusted by changing the output frequency ft of the variable oscillation circuit 1. but,
There is a problem in that the rotational speed can only be adjusted in the positive direction around the reference frequency f8, and cannot be adjusted in the negative direction.

The present invention aims to provide a motor rotation speed adjusting device that solves the above-mentioned problems by further improving the device shown in FIG. 1, and adjusts the motor rotation speed in both positive and negative directions around the reference frequency f8. It made it possible.

The embodiment will be described below with reference to FIG. 2, and blocks having the same functions as those explained in FIG. 1 are given the same reference numerals.

The embodiment shown in FIG. 2 has the configuration shown in FIG. circuit 5
17M between the other input terminal of the
A frequency divider circuit 10 is inserted, and the output frequency of the frequency divider circuit 9 is f.

/N, the output frequency of the frequency dividing circuit 10 becomes f8/M, and the output frequency of the frequency subtraction circuit 5 becomes.

Note that both N and M are integers and N<M.

In the phase control loop, when the two input frequencies to the phase comparator circuit 2 and the phases match, a synchronized state is achieved and the state becomes stable, so in this case, the following relationship always holds true and becomes stable.

The output frequency f at this time.

When the output frequency of the variable oscillation circuit 1 is set to f,1, f.

-f8, and the frequency control type motor 7 has a reference frequency of f8.
rotates in proportion to.

Here, if set, fo>f8 and the frequency control motor 7's rotation speed shifts in the positive direction, and vice versa, fo<f8 and the frequency control motor 7's rotation speed shifts in the positive direction.
The rotational speed of is shifted in the negative direction.

To explain specifically, f8=90KHz, N=9,
Assuming M=10, fo-9(9+ft),
When ft=IKHz, fo-90KHz, and the rotational speed deviation of the frequency-controlled motor 7 is 0% with respect to the reference frequency f8.

If ft=0.5KHz, fo-85.5KHz, and if ft=15KHz, fo=94.
5KHz, the frequency f.

are -5% deviation and +5% deviation from the reference frequency fS, respectively.
As a deviation, the rotation speed of frequency control type motor 7 is ±5%.
It can be changed in both positive and negative directions.

As is clear from the above description, the present invention is capable of reliably adjusting the rotational speed of the motor in both positive and negative directions around the reference frequency with a relatively simple configuration.

Therefore, it is particularly effective when applied to equipment such as record players and tape recorders in which it is desired to adjust the rotation speed in both positive and negative directions around a predetermined rotation speed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the main parts of a motor rotation speed adjusting device considered as an improvement over the conventional example, and FIG. 2 is a block diagram of the main parts of an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Variable oscillator circuit, 2... Phase comparison circuit, 3... Filter circuit, 4... Voltage controlled oscillator, 5...・Frequency subtraction circuit, 6,
9, 10... Frequency dividing circuit, γ... Frequency control type motor, 8... Changeover switch, 11...
...Reference frequency source.

Claims (1)

[Claims] 1. A variable oscillation circuit that can adjust the oscillation frequency, a first input terminal to which an output signal of the variable oscillation circuit is input, and a second input terminal to which a comparison signal is input. A phase comparison circuit that generates an error signal corresponding to the phase difference of each input, a filter circuit for smoothing the output of the phase comparison circuit, and an oscillation frequency controlled according to the output of the filter circuit. a voltage controlled oscillator, a first frequency dividing circuit for dividing the output frequency of the voltage controlled oscillator, a second frequency dividing circuit for dividing the reference frequency, and the second frequency dividing circuit for dividing the output frequency of the voltage controlled oscillator. a frequency subtraction circuit that calculates the difference between the output frequency of the frequency divider circuit and the output frequency of the first frequency divider circuit, and inputs the difference output as the comparison signal to the second input terminal of the phase comparison circuit; , comprising a third frequency dividing circuit for frequency dividing the output frequency of the voltage controlled oscillator, and a frequency controlled motor rotating in proportion to the output frequency of the third frequency dividing circuit, A motor rotation speed adjusting device, characterized in that the rotation speed of the motor can be adjusted by changing the oscillation frequency of an oscillation circuit. 2. The motor rotation speed adjusting device according to claim 1, wherein the frequency division number of the first frequency division circuit is smaller than the frequency division number of the second frequency division circuit.