KR920002326Y1 - For vtr auto tracking device - Google Patents

Abstract

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Description

Automatic tracking device of video cassette recorder (VCR)

1 is a circuit diagram of the device of the present invention.

(A)-(j) is a signal waveform diagram of each part for demonstrating operation | movement of this apparatus.

* Explanation of symbols for main parts of the drawings

1: switching signal input 2: rising and falling edge detector

3: counter 4: binary comparator

5: 1 / N divider 6: Low pass filter

7: Adder 8: Motor Drive Amplifier

9: capstan motor 9´: capstan pickup head

10: speed control circuit 15: phase control loop

The present invention relates to an automatic tracking device of a video cassette recorder (VCR), and more particularly, to an automatic tracking device of a VCR which controls the rotation speed of a capstan of a VCR by an output signal of a pulse generator and a reproduction vertical synchronization signal.

Conventionally, in the phase control (i.e., tracking control) of the capstan of a VCR, a control signal is recorded in accordance with the input video vertical synchronization at the time of recording, and read out at the time of reproduction so as to be synchronized with the reference clock. The tracking adjustment volume for compensating for the error due to the etc. is provided separately, and the structure is complicated, and the user has to manually operate it manually, and also has a disadvantage in that a number of component composition scores increases.

The present invention is designed to solve the above-mentioned drawbacks. Head switching is generated by the pulse generator head mounted in the drum inside the VCR so as to omit the control head and the tracking volume and the circuit elements associated with the tracking volume. Regeneration vertical synchronization signal from the rising edge and falling edge of the head switching signal by the vertical synchronization signal separated from the reproduction signal by using the vertical synchronization signal corresponding to the signal and the position of the control signal. VCR which controls the phase of the capstan by controlling the length and time corresponding to 6.5H (1H = 63.5μsec) between the switching signal of the head drum and the vertical synchronous signal to prevent the tracking error caused by mechanical error. It is an object of the present invention to provide an automatic tracking device of the present invention according to the accompanying drawings More specifically the configuration as follows.

As shown in FIG. 1, the automatic tracking device of the present invention raises and lowers the switching signal 1 generated by drum rotation from an unillustrated pulse generator head installed at a predetermined position around the drum motor inside the VCR. It is applied to the detector (2), and the output terminal of the rising and falling edge detector (2) is connected to the counter (3), the counter (3) to divide the color carrier frequency (fsc = 3.58MHZ) to 1 / N The output of the divider 5 and the vertical synchronous signal for dividing a field for each screen are applied, and the counter value of the binary comparator 4 to which the count value of the counter 3 and the output of the divider 5 are applied. The comparison error output is applied to the non-inverting input terminal (+) of the adder (7) through the low pass filter (6), and the output terminal of the adder (7) is connected to the capstan motors (9) through a known motor driving amplifier (8). Capstan pickup head (9 ') installed close to the capstan shaft (11) The output stage is through the speed control circuit 10 of a known inverting input terminal of the adder (7) (-) to the connection to be applied to hayeoseo, reference numeral 15 is a phase locked loop.

Referring to the effects of the present invention configured as described above with reference to (a)-(j) of FIG. 2 as follows.

That is, as shown in FIG. 1, the 1 / N divider 5 to which the color carrier (3.58MHZ) is applied is used to generate a reference frequency used to generate a constant reference pulse signal based on the color signal of the input image signal. (3.58MHZ) is divided by 1/8 to output, where 1/8 divided by fsc / 8 = 447.443KHZ (2.2348 µsec).

At the same time as the rising and falling, the detector 2 is applied with a switching signal 1 such as 2a, which is generated every time the drum is rotated by 180 ° from the not shown pulse generator head mounted in the head drum. ) Determines the rising edge and falling edge state of the switching signal 1 and outputs a switching edge detection signal such as 2b.

At this time, the counter 3 counts the same clock 447.443 KHZ divided by the divider 5, and the counting time is when the counting starts at the edge detection shaping signal of the switching signal 1, and is separated from the reproduction signal. When a vertical synchronous signal such as 2c is input to the counter 3, the value of counting the switching edge detection signal of the detector 2 is initially counted and a value of the same value as the 2d degree when the vertical synchronous signal is inputted to the binary comparator ( To 4).

The binary comparator 4 by the output of the counter 3 has a position and a counter of the vertical synchronizing signal in the video signal currently input based on the division clock 447.443KHZ outputted from the divider 5. 3) compares a constant coefficient output value of 6.5H and outputs a pulse width modulated wave PWM equal to the 2e degree corresponding to the comparison error, wherein 6.5H corresponds to the coefficient value set in the binary comparator 4 itself. In the case of fsc / 8, the binary value is about 185.

That is, 1/3579545 x 8 = 2.2349 (µsec), 6.5H = 63.5 µsec x 6.5 = 412.75 µsec, and 412.75 / 2.2349 = 184.68 (# 185).

In this way, a pulse width modulated wave equal to the 2e degree corresponding to the comparison error value of the binary comparator 4 is applied to the non-inverting input terminal (+) of the adder 7 through the low pass filter 6, and its inverting input terminal (-). The rotational speed detection signal of the capstan motor 9, such as the second f degree generated from the capstan pickup head 9 'of the reference pulse generator, which detects the rotational speed of the capstan motor 9 and records or reproduces the recording pulse, The rotation speed error value of the capstan motor 9 is applied by operation of a known speed control circuit 10 composed of a pulse amplifier, a gaeta pulse-o delay mono multivibrator, and a comparator, as shown in FIG. do.

Therefore, the adder 7 has a comparison error value output from the comparator 4 of the phase control loop 15 through the low pass filter 6 and a rotation speed error equal to the second j degree output from the speed control circuit 10. The value added by adding the signal is output from the driving amplifier 8 of the capstan motor 9.

Therefore, the phase control loop 15 has a comparator 4 when the phase of rotation of the capstan motor 9 with respect to the output of the adder 7 is faster, that is, when the vertical synchronization signal is later than the head switching edge detection signal. In contrast, when the phase of the capstan motor 9 becomes slow, the phase control loop 15 is operated so that the mark of the pulse width modulated wave becomes smaller. (9) to control the speed and phase.

As described above, according to the present invention, the head switching signal generated by the pulse generator head mounted in the drum and the vertical synchronizing signal corresponding to the position of the control signal are used. By controlling the length and time corresponding to the position of H to automatically control the phase of the capstan, tracking errors due to mechanical errors can be suppressed in advance, as well as omitting the tracking control head, tracking volume and related circuits. It is a very useful design that can simplify the circuit configuration or reduce the production cost.

Claims (1)

In the capstan control means of the control recording and reproducing apparatus, the capstan pick-up head 9 'which is provided in close proximity to the capstan shaft 11 and detects the speed information of the capstan shaft 11, and the output of the pick-up head 9'. A speed control means 10 for controlling the speed, a detector 2 for detecting rising and falling edges of the input switching signal 1 generated by the drum rotation or by a pulse generator, and 1 of the reproduced video signal. A divider 5 for dividing the frequency generated from the vertical synchronization signal detected at each screen and an arbitrary oscillator, a counter 3 for counting the output signal therefrom and the output of the detector 2, and Phase control means (15) comprising a comparator (4) for comparing the output of the counter (3) and the output of the divider (5), a low pass filter (6) connected thereto, and the speed control means (10). And an adder 7 for adding the output of the phase control means 15, and the adder 7 An automatic tracking device for a video cassette recorder (VCR), characterized in that it comprises a motor drive amplifier (8) and a capstan motor (9) connected thereto controlled by the output of the amplifier.