KR920000443Y1 - Velocity controll circuit of capatan motor - Google Patents

Abstract

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Description

Speed control circuit of capstan motor

1 is a circuit diagram of a preferred embodiment of the present invention.

2 is a diagram schematically showing a mechanism for transmitting rotational drive force between the winding rail and the supply rail of the VTR.

* Explanation of symbols for the main parts of the drawings

1: Key metrics part 2: Micom

3: Wester integrated device 4: Synthetic circuit

5: motor driver 6: capstan motor

7: Tape protection circuit 10: Free run detection and mute part

11: frequency generator 12,24: frequency. Voltage converter

12A, 24A: Waveform Shaper 12B, 24B: Monostable Multi

12C, 24C: Low Pass Filler 13,25: Comparator

30: real speed detection and reduction unit 21, 22: reflective photo couple

23: switch means 31: supply rail disk

32: take-up disk Q1, Q2: switching transistor

The present invention relates to a speed control circuit of a capstan motor, and more particularly, to a speed control circuit of a capstan motor that can protect the tape by preventing the tape from breaking or stretching when the tape is running.

In general, the capstan motor in the VTR is a motor that supplies power to the tape traveling system. It is controlled by a motor driver that receives a motor driving voltage signal whose voltage varies depending on an operation mode from a servo integrated device. do.

In the tape winding mode (FF: FAST FORWARD), as shown in Figure 2- (a), the rewind (REW: REWIND) idler 33 and TAKE UP REEL receive power from the capstan motor. The winding (FF) idler 34 is interposed between the disks 32 so that the rotation of the REW idler 33 is transmitted to the take-up rail disk 32 via the FF idler 34 so that the tape is wound from the supply rail to the take-up rail. Is brought in.

In the tape rewind (REW) mode, the REW idler 33 is squeezed onto the supply rail disk 31 so that the rotation of the REW idler 33 is transmitted to the supply rail disk 31 to rewind the tape from the winding rail to the supply rail. It becomes.

In the above-described FF and REW modes, the winding rail disk and the supply rail disk are rotated by a capstan motor of a constant speed through the REW idler, so that the winding speed is maintained at a constant speed from the beginning to the end, but the winding rotation radius is increased as the tape winding amount is increased. This increases the tape tension force acting in the tangential direction of the winding turning radius, and accordingly the tape feeding rail has a relatively smaller radius of rotation, so that the rotation speed is gradually increased so that the speed is very high just before the end of the FF and REW operation. Will rotate. Therefore, there was a closure where the tape stretched just before the end of the FF and REW operation.

In severe cases, the tape broke.

In addition, since the tape odometer receives rotational power from the capstan motor, there is a closed end of the tape when the capstan motor is free run due to a circuit error.

Therefore, in order to solve the problems of the prior art as described above, the present invention detects the rail rotation to supply the tape during the FF and REW operation to decelerate the capstan motor, and also detects the free run state of the capstan motor to freerun. It is to provide a speed control circuit of a capstan motor that can protect the tape by preventing the tape from stretching or breaking by stopping the motor.

In order to achieve the above object, the present invention supplies a mode control signal to a servo integrated device from a microcomputer that recognizes key operation of a key matrix unit, and in the servo integrated device, a motor is connected to a motor driver for driving a capstan motor. In controlling the tape running by supplying a drive voltage signal, a free-run detection and muting section for stopping the capstan motor by muting the motor drive voltage signal during free run of the capstan motor, and during tape FF and REW. When the rotational speed of the rail supplying tape is more than a certain speed, a tape protection circuit having a rail speed and a deceleration section for decelerating the rotational speed of the rail winding the tape is connected between the servo accumulator and the motor driver. It is characterized by.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, the key matrix unit 1 recognizes the mode signal selected according to the key operation in the microcomputer 2 and outputs the recognized mode control signal. The servo integrated device 3 outputs the speed control signal set according to the mode control signal supplied from the microcomputer 2 and the phase control signal set in phase comparison with the image synchronization signal, and outputs the speed control signal and The phase control signal is synthesized in a synthesis circuit 14 composed of operational amplifiers U1, resistors R1-R5, and capacitors C1-C4, and the motor driving voltage of the motor driver 5 through the resistor R6. It is supplied to the signal input terminal.

The motor driver 5 drives the capstan motor 6 according to the level of the input motor driving voltage signal.

The motor driving voltage signal of the synthesizing circuit 4 is connected to the motor driver 5 through the tape protection circuit 7 to the speed control circuit of the known capstan motor configured as described above.

The tape protection circuit 7 includes a trirun detection and muting unit 10 and a real speed detection and reduction unit 20. The free run detection and muting unit 10 is connected to the capstan motor 6. The pulse output of the magnetically coupled frequency generator 11 is DC-voltageized to the frequency and voltage converter 12 and the DC voltage circuit is set by the resistors R8 and R9 of the comparator 13. When the DC voltage signal is larger than the reference signal by comparing the signal with the level comparator U2, the output terminal of the level comparator U2 is connected to turn on the switching transistor Q1 through the inverter G1 and the collector ground transistor Q1. ) Is connected to the motor driving voltage signal input terminal of the motor driver 5 to mute the motor driving voltage signal during the free run operation of the capstan motor, and the rail speed sensing and deceleration unit 20 ) Winding disc 32 and feeder The disk 31, each pulse output from the reflection type photo-couplers 22, 21, respectively, optically coupled to the microprocessor (2) It is connected to be supplied to the frequency and voltage converter 24 through the switch means 23 so as to be selected according to the mode control signal, and the DC voltage signal output from the frequency and voltage converter 24 is resistance R10 of the comparator 25. And the output terminal of the level comparator U3 such that the switching transistor Q2 is turned on through the inverter G2 when the DC voltage signal is greater than the reference signal compared to the reference signal and the level comparator U3 set by the resistor R11. Connect the emitter of the collector ground transistor Q2 to the motor driving voltage signal input of the motor driver 5 through the resistor R7, and the rotation speed of the tape supply rail By dividing the driving voltage signal into the resistor R6 and the resistor R7 and supplying it to the motor driver 5, the speed of the capstan motor 6 is reduced to reduce the tape winding speed.

The frequency and voltage converters 12 and 24 have the same configuration, and the input pulses are waveform-shaped by the waveform shaper 12A and 24A, and the waveform-formed pulse signal is used as a trigger signal. Square wave outputted by triggering the?) Is outputted as a DC voltage signal through the low pass filters 12C and 24C.

Therefore, the level of the D.C voltage signal proportional to the frequency of the input pulse signal can be obtained.

The operation and effects of the present invention configured as described above are as follows.

First, in the FF operation, the microcomputer (2) The mode control signal becomes " H " so that the switch means 23 is switched to the FF position, and the output voltage Vo of the synthesizing circuit 4 is transferred to the motor driver 5 by the motor driving voltage signal. ) Is driven at the rotational speed set by the Vo voltage signal.

The take-up rail disk 32 receives the rotational force from the capstan motor 6, rotates at a constant speed, and the tape is wound from the supply rail to the take-up rail. As the winding amount increases, the rotational radius of the winding rail becomes larger and the rotational radius of the supply rail becomes smaller, so that the rotational speed of the supply rail disk 31 is increased, and the reflective photo coupler 21 coupled to the supply rail disk 31 is applied. Since the frequency of the pulse signal output from is increased, the frequency, the DC output level of the voltage converter 24 rises above the reference signal level, the output of the level comparator U3 goes from low to high, and the transistor through the inverter The low signal is applied to the base of Q2.

Therefore, since the transistor Q2 is turned on, the output voltage Vo of the synthesis circuit 4 is divided by the resistor R5 and the resistor R7 to divide the divided signal Va.

Then, it is supplied to the motor driving voltage signal input terminal of the motor driver 5. Accordingly, the capstan motor 6 is reduced in the rotational speed by the reduction of the drive voltage and the winding speed of the tape is reduced. Therefore, the speed of the supply rail disk 31 is reduced and the tensile force applied to the tape is also reduced, thereby preventing the tape from being stretched or broken. Similarly, when the REW operation Since the mode control signal "L" switches the switch means 23 to the REW position, the reflective photocoupler 22 coupled to the take-up disk 32 is selected, and the tape is extended by the same operation as in the above-described FF operation. Can be prevented or broken.

When the capstan motor 6 is preturned due to a circuit error, the frequency of the pulse signal output from the frequency generator 11 is increased. D.C. of the voltage converter 12. Since the output level rises above the reference signal level and thus becomes less than the output of the level comparator U2, and is applied as a low signal to the base of the transistor Q1 through the inverter G1, the output voltage of the synthesis circuit 4 ( Vo) is bypassed to ground, and the motor driving voltage signal supplied to the motor driver 5 is muted.

Therefore, the capstan motor 6 stops the preturn operation, thereby preventing the tape break.

As described above, the present invention can prevent the tape from stretching or breaking due to the increase in the tape tension during the FF and REW operation of the tape traveling system by the deceleration control of the tape winding speed. It is possible to protect the tape by monitoring the freeton operation of the capstan motor which is being stopped and stopping the capstan motor during the preton operation.

Claims (3)

The mode control signal is supplied to the servo integrated device 3 from the microcomputer 2 that recognizes the key operation of the key metrics unit 1, and the cap integrated motor 4 drives the capstan motor 6. In controlling the tape running by supplying a motor driving voltage signal to the motor driver 5, the capstan motor 6 is muted by muting the motor driving voltage signal during the free run of the capstan motor 6. Free run detection and muting unit 10 to stop the operation, and the rail speed detection and deceleration unit to decelerate the rotational speed of the rail winding the tape when the rotational speed of the rail supplying the tape at the time of the tape FF and REW ( 20. A speed control circuit for a capstan motor, characterized in that the pro protection circuit (7) is connected between the servo integrated source (4) and the motor driver (5). According to claim 1, wherein the free-run detection and muting unit 10 is a frequency generator 11 magnetically coupled to the capstan motor 6 and a voltage corresponding to the output frequency of the frequency generator 11 Frequency at which the signal is generated. Voltage. Transducer 12 and said frequency. A comparator 13 for determining a free run state by comparing the voltage signal of the voltage converter 12 with a set reference signal, and a switching transistor Q1 for muting the motor driving voltage signal when the comparator 13 detects a free run. Capstan motor speed control circuit, characterized in that consisting of. The method of claim 1, wherein the rail speed detection and deceleration unit 20 is a reflective photocoupler (21) (22) and optically coupled to the supply rail disk 31 and the winding rail disk 32, respectively, Reflective photo couplers (21) and (22) of the A frequency for generating a voltage signal corresponding to the output frequency of the switch means (23) selected according to the mode control signal and the reflective photocoupler (21 DR 22) selected through the switch means (23). A voltage converter 24 and the frequency. A comparator 25 for determining whether the tape winding speed is decelerated by comparing the voltage signal of the voltage converter 24 with a set reference signal, and a resistor for dividing the motor driving voltage signal when the deceleration state of the comparator 25 is detected. (R7) and a switching transistor (Q2), characterized in that the capstan motor speed control circuit.