KR0152767B1 - Control circuit for capstan - Google Patents

Abstract

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Description

Capstan motor control circuit

1 is a conventional capstan motor control circuit diagram.

2 is a waveform diagram of each part according to a conventional circuit.

3 is a capstan motor control circuit diagram according to the present invention.

4 is a correlation characteristic diagram of a phase of a capstan motor and a phase detection voltage.

5 is a correlation characteristic diagram of a detection frequency and a speed control voltage of a capstan motor.

Figure 6 is a waveform diagram of each part according to the circuit of the present invention.

* Explanation of symbols for main parts of the drawings

A: Phase comparator B: Divider

C) frequency / voltage converter d: amplifier

E: Frequency detector bar: Capstan motor

4: Mixer A: Negative feedback circuit

Ruler: Motor drive circuit 1: Voltage limit circuit

2: driving power switching circuit 3: high speed discriminator

4: deceleration discriminator 5: differential circuit

Q1-Q3, Q10, Q11: Transistors D1-D3, D10, D11: Diode

ZD1: Zener Diodes C1, C10: Condenser

R1-R7, R10-R15: Resistor IC1, IC2: Operational Amplifier

The present invention is characterized in that the response time of the capstan motor (stable time to steady state) is shortened during transient response of the capstan motor which drives the tape in the VCR or camcorder, that is, when the speed fluctuations such as start-up, high-speed playback initiation and end. The present invention relates to a capstan motor control circuit, which is suitable for improving the efficiency of the circuit.

In a conventional VCR, for example, at the time of reproduction or shifting, there is a function such as high speed reproduction stop. In this case, the high speed playback should increase the rotation speed of the motor to correspond to the high speed playback such as 7 times or 125 times faster than the constant speed playback. In this case, the motor voltage should be constant speed playback to increase the motor's driving torque. Increasing circuitry was required, so that the high-speed playback screen could be seen stably and the response could be quick at the beginning of the high-speed playback.

However, this circuit configuration can only correspond to the initial response of high speed regeneration, and the capstan motor has a large mass even when the speed control agent is in constant speed because the power supply voltage (V _M ) of the capstan motor is reduced by the constant speed regeneration in the high speed regeneration. There was a problem that the response was slowed down, and the conventional circuit configuration was unable to respond quickly to the change of the driving mode of the capstan motor, i.e., at the moment of stopping from the beginning of the constant speed reproduction and from the constant speed reproduction.

The configuration and operation of the conventional capstan motor control circuit will be described in detail with reference to FIGS. 1, 2, 4, and 5, and the capstan motor (bar) is a drive circuit of a motor operated by a control voltage (Vc). Rotation according to the operation of (i), and the frequency detecting device (e) which detects the speed in proportion to the rotation as the capstan motor (bar) rotates is connected, and the detection frequency signal (fc) of the frequency detecting device (e) 2 degrees H waveform) is amplified by the amplifier (d) and input to the frequency / voltage converter (d), and the output of the amplifier (d) is input to the divider (b) and the output signal divided by 1 / N (f _N). (B waveform of FIG. 2) is obtained, and the output of the dividing period (b) is inputted to a phase comparator which performs a phase comparison with the reference signal a similar to the waveform of FIG. The frequency / voltage converter c outputs the speed control voltage Vf (Fig. 2 D waveform) and the phase comparator outputs the phase control voltage Vo (C waveform in Fig. 2). These signals, that is, the output phase control voltage (Vo) of the speed control voltage (Vf) phase comparator (A), which are the outputs of the frequency / voltage converter (C), are respectively input to the + input terminal and the-input terminal of the mixer (G). At this time, the mixer is composed of an operational amplifier IC. On the other hand, the mixer output (Vc) (Fig. 2 E waveform) has limited gain by the negative feedback circuit (H) so that the capstan motor control circuit can operate in the stable region, and the control voltage (Vc) The motor driving circuit (child) is input to the motor driving circuit (child) is connected to the capstan motor (bar), and the output (Vo) of the phase comparator (a) is a resistor (R1, R2) diode (D1, D2) capacitor ( The voltage limit circuit 1 composed of C1 is connected, and the motor driving circuit is composed of transistors Q1-Q3, diode D3, zener diode ZD1 resistor R3-R7, and high-speed reproduction high signal (c). The driving power switching circuit 2, which is controlled by operation), is connected to form a capstan motor control circuit.

On the other hand, as shown in FIG. 4, the phase comparator A decreases the phase control voltage Vo when the motor phase F _N is fast with respect to the reference phase a, and when it is slower than the reference phase, the phase control voltage Vo. This has an increasing characteristic.

In addition, as shown in FIG. 5, the main professor / voltage converter (c) increases the detection frequency proportionally as the rotational speed of the motor increases, and accordingly, if the detection frequency signal fc is higher than the target frequency, the speed control voltage Vf Is increased and the speed control voltage Vf is lowered when the detection frequency signal fc is lower than the target frequency. In this way, the phase control voltage Vo and the speed control voltage Vf are controlled so as to coincide with the rotational speed and phase of the capstan motor bar and the reference phase. In more detail, if the speed of the capstan motor (bar) is lowered by some cause than the target speed, the detection frequency (fc) is lowered, and thus the speed control voltage (Vf) is lowered, and thus the -input terminal voltage of the mixer (g). Since the control voltage Vc, which is the output of the mixer, increases, the driving current output of the motor driving circuit increases, and the capstan motor (bar) is controlled to rotate rapidly, while the capstan motor (bar) If the phase (f _N ) is faster than the reference phase (a), the phase control voltage (Vo) is lowered and the + terminal voltage of the mixer (g) is lowered. Therefore, the control voltage (Vc) is decreased to increase the rotational speed of the capstan motor (bar). The rotational phase is controlled so as to match the reference phase, and the phase control voltage (Vc) resists the phase control voltage because the detection gain of the phase comparator changes from 0V to Vcc as shown in FIG. (R1, R2) diode (D1, D2) cone Is limited by the standing (C1) limits the voltage circuit 1 consisting of.

In other words, the phase control voltage Vo of the phase comparator A is equal to Vo = Vcc / 2 ± 0.6 [V] by the voltage Vcc / 2 of the resistors R1 and R2 and the voltage drop 0.6V of the diodes D1 and D2. It is limited (limit) within and is applied to the + input terminal of the mixer, and the control circuit is operated stably.

On the other hand, if the high speed regeneration signal (c) is changed to a high state as shown in FIG. 2 F waveform to improve the response characteristics during the high speed regeneration in the conventional capstan control circuit, the motor rotation speed is lower than the target value during the transient period of t1. The speed control voltage Vf drops rapidly (FIG. 2, D waveform), and the phase control voltage Vo increases (C waveform of FIG. 2).

Therefore, the phase control voltage (Vc) output from the mixer (G) is also increased (Fig. 2, E waveform) to increase the motor speed at high speed. At this time, the high speed regeneration signal (c) is divided into frequency divider (B) and frequency / voltage converter. The target value is entered in (C) to change the high speed playback speed. On the other hand, in order to sufficiently increase the driving torque of the motor during such high speed regeneration, a driving power switching circuit 2 for selectively changing the motor driving voltage V _M is used. The high speed regeneration high signal generates a resistance (R3, R4). When the transistor Q2 is turned on and the transistor Q2 is turned on, a low potential is applied to the base of the transistor Q1 through the resistor R6 so that the transistor Q1 is turned on so that the emitter-collector of the transistor Q1 is turned on. B ⁺ motor voltage (d) is applied to the driving circuit (I), and the voltage (V _M ) of the driving circuit is increased during high speed regeneration.

In FIG. 2, the change state of the motor driving circuit voltage V _M (FIG. 2 G waveform) is divided into V _M1 and V _M2 . V _M1 is a voltage determined by the zener diode ZD1 of the drive power switching circuit 2 and is supplied to the drive power during constant speed regeneration by the transistor Q3 resistor R7 and the zener diode ZD1 diode D1. .

As described above, in the conventional configuration, the response time t1 can be reduced by changing the driving power in the t1 section. However, as described above, the capstan motor has a large mass as described above in the instant of changing from the fast playback to the constant speed playback. Also, there was a problem that the response time (to) was not decreased, and this problem caused the inconvenience that the settling time of the playback screen was long, and the mass of the motor could not be increased. Rotation of uniformity or wow, there was a disadvantage that can not reduce the flutter (WOW, Fultter).

The present invention solves these shortcomings and also improves the response characteristics when changing the mode of the capstan motor, that is, when the mode is changed from stop to constant regeneration driving, constant ↔ high speed regeneration, and constant ↔ stop screen. Therefore, it is designed to operate properly according to each motor rotation speed corresponding state.

Referring to the configuration of the present invention in FIG. 3, the capstan motor (bar) and the capstan motor (bar) rotate in accordance with the operation of the motor driving circuit (operator) operated by the control voltage (Vc). Frequency detecting device (E) which performs speed detection proportionally, amplifier (A) for amplifying detection frequency signal (fc) of frequency detecting device (E), and frequency for frequency / voltage conversion by receiving output of amplifier (D). A voltage comparator (C), a divider (1) that receives the output of the amplifier (D) and divides it by 1 / N, a phase comparator (A) that receives the output of the divider (B), and compares the phases; A mixer (a) which receives the output Vo of (a) and the output Vf of the frequency / voltage converter (c), a negative feedback circuit (a) which limits the gain of the mixer (g) output, and Motor control circuit for driving the capstan motor (bar) in response to the output of the mixer, and before the phase control that is the output of the phase comparator (a) Of the voltage limit circuit for limiting a change (1), a transistor (Q1-Q3), a Zener diode (ZD1) resistance is composed of (R1-R7) the drive power supply switching circuit for selectively changing the motor drive voltage (V _M) ( In the motor control circuit composed of 2), the rotational torque increase state of the motor is transmitted to each signal of the phase control voltage Vo in the phase modulator a and the speed control voltage Vf of the frequency / voltage converter d. And the high speed discriminator 3 and the speed reducer 4 for determining the reduced state, and the output V1 of the high speed discriminator 3 is a resistor (R3, R4) transistor of the driving power switching circuit 2 ( Q2) and the driving power increasing circuit by the resistors R6 and R5 transistor Q1 are operated, and the output V2 of the deceleration discriminator 4 is passed through the differential circuit 5 of the capacitor C10 resistor R12. The collector of the transistor Q10 operated by the applied reference signal a and the base of the transistor Q11 operated by the transistor Q10. By it is commonly connected through a resistor (R13) to change the state of the forward / reverse signal (b) inputted to the (i) the motor driving circuit to generate a reverse torque during deceleration it is operated so as to obtain the response is rapid deceleration characteristics.

The detailed operation of the present invention will be described in detail with reference to FIGS. 3 and 6, when the high-speed playback high signal (c) of FIG. 4) and the frequency / voltage converter (C) are converted to the high speed regeneration state, and the speed control voltage Vf (FIG. 6F waveform) in the third frequency / voltage converter C as shown in FIG. 6 is t1. During the interval of, the voltage drops rapidly, and the phase control voltage Vo (Fig. 6 E waveform) rises by ΔVo (about 0.6V). The speed control voltage Vf is connected to the + terminal input of the operational amplifier IC2 of the deceleration discriminator 4 through the-terminal input of the operational amplifier IC1 of the high speed discriminator 3 and the diode D11. The resistor R11 connected between the + terminal input of the operational amplifier IC2 and the ground is a distribution resistor.

On the other hand, the phase control voltage Vo from the phase controller A is applied to the operational amplifier IC1 of the high speed discriminator 3 through the negative terminal input of the operational amplifier IC2 of the speed reducer 4 and the diode D10. The resistor R10 connected between the + terminal input of and the + terminal of the operational amplifier IC1 and the ground is a distribution resistor.

As described above, the phase control voltage Vo rises + 0.6V and the speed control voltage Vf drops sharply during the t1 period conversion, i.e., in the t1 section, so the output signal V1 of the operational amplifier IC1 is high. A state (G waveform of FIG. 6) is obtained, and the output signal V2 of the operational amplifier IC2 is in a low state (I waveform of FIG. 6).

In addition, in the high speed regeneration section after the t1 section, the speed control voltage Vf decreases by ΔVf and is driven while increasing the control voltage Vc of the motor, so that the output signal V1 of the operational amplifier IC1 (Fig. 6G) Waveform) and the output signal V2 (Fig. 6 (I) waveform) of the operational amplifier IC2 are maintained as in FIG.

Also, when the operation state is reduced from the high speed regeneration state to the constant speed regeneration state, as shown in FIG. 6C, the high speed regeneration high signal is turned low to change the capstan control circuit to the constant speed state. The output signal Vf of the converter c is rapidly increased, and the capstan motor bar is decelerated from this time.

That is, in Fig. 6, the speed control voltage Vf is increased (Fig. 6F waveform) and the phase control voltage Vo is decreased approximately -0.6V (Fig. 6E waveform) in the period t2.

Accordingly, the high speed discriminator 3 and the deceleration determiner 4 for discriminating the voltages of the speed control voltage Vf and the phase control voltage Vo are calculated because the Vf voltage is greater than the Vo voltage. The output V1 of the amplifier IC1 goes low (Fig. 6 (G) waveform), and the operational amplifier IC2 output V2 of the deceleration discriminator 4 is in a high state (Fig. 6 (I) waveform). )

At this time, the reference signal (a) (Fig. 6 (A) waveform) is a differential pulse (V3) as shown in Fig. 6 (H) by a differential circuit 5 composed of a capacitor (C10) resistor (R12). R15 is applied to the base of the transistor Q10, and when the operational amplifier IC2 output V2 of the deceleration discriminator 4 is high, the operation of the resistor R10 and the transistor Q10 is performed. (B) A signal V4 such as a waveform is applied to the base of the transistor Q11, and this signal turns on and off the transistor Q11 so that the forward / reverse signal b passes through the resistor R14. ), The deceleration time of the capstan motor (bar) is remarkably reduced by switching the signal V5 applied to) to the reverse driving state for the period t3. That is, the deceleration section t2 is obtained as shown in FIG. 6 by reducing the time of the conventional deceleration section t0 shown in FIG. In other words, the forward capstan motor (bar) in the high-speed rotation state generates the reverse drive pulse V4 (Fig. 6 (b) waveform) of the signal V5 applied to the motor drive circuit (i) in the deceleration section. By shortening t2, responsiveness is greatly improved. In addition to the above-described high speed regeneration mode, the circuit of the present invention sets the detection level of each of the speed control voltage Vf and the phase control voltage Vo by the diodes D10 and D11 to respond to the high speed response and the deceleration response, respectively. Since it is possible to respond automatically, it has the effect of having a quick response characteristic at the moment of changing the speed such as stop → constant speed playback, constant speed → stop screen playback.

Claims (1)

A high speed discriminator for controlling the motor driving voltage V _M input to the motor driving circuit driving the capstan motor according to the speed control voltage Vf and the phase control voltage Vo, and the speed control voltage Vf and phase control A deceleration discriminator for outputting a signal for deceleration according to the voltage Vo, a differential circuit for differentiating a reference signal input from the outside, and a motor driving circuit from the outside according to the output of the differential circuit and the output of the deceleration discriminator Capstan motor control circuit comprising a direction changer for changing the state of the forward / reverse signal input to.

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