KR920007938Y1 - AUTO TRAC FINDING LOCK CIRCUIT OF 8m/m VTR - Google Patents

Abstract

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Description

ATF lock circuit of 8mm video tape recorder

1 is an ATF lock circuit diagram of an 8 millimeter video tape recorder according to the present invention.

2 is a waveform diagram of each part of FIG.

3 is a tape stop position and an ATF lock signal waveform diagram.

* Explanation of symbols for main parts of the drawings

1: divider 2: video head

3: buffer 10: pilot signal generator

20: adder 30: switch

40: low pass filter (LPF) 50: modulator

60: band pass filter 70: peak detector

80: comparator 90: sampling hold

100: Schmitt

The present invention relates to a video, and more specifically, a millimeter video tape recorder that detects a tape stop position by using an ATF (Auto Trac Finding) lock during slow operation and adds or subtracts a tape amount when the frame is advanced. ATF lock circuit of the present invention.

In general, in the case of a video tape recorder, when the head reads each track during slow operation, if the first stop position is shifted from the normal state, the stop position is shifted from the normal state, causing noise and deteriorating image quality. .

The present invention aims to solve this problem, and provides an ATF lock circuit of an 8mm video tape recorder which stops the tape in the absence of noise output.

A feature of this invention for achieving this object is a pilot signal generator for generating a pilot signal, an adder connected to the pilot signal generator for adding luminance and color difference recording signals and a pilot signal, and a video head. An 8 mm video tape recorder, comprising: a low pass filter connected to a flyback signal output and detecting a pilot signal; A modulator coupled to the low pass filter and the pilot signal generator to form a reference pilot signal and four pilot signals by summation to 16 KHz and 46 KHz; A band pass filter coupled to the modulator; A peak value detector coupled to the band pass filter to detect peak points of signal levels; A comparator connected to the peak detector for comparing an output of 16 KHz and outputting an ATF error signal; A simplifying hold coupled to said comparator to " turn on " in a logic " high " state of a radio frequency switching pulse signal; And a schmitt which is connected to the sampling hold and schmitts the sampled and held signal to produce an ATF lock signal.

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

1 is a diagram showing an ATF lock circuit of a milli video tape recorder according to the present invention, and a luminance and chrominance recording (Y + CREC) signal to a pilot signal generator 10 for generating a pilot signal. An adder 20 for adding a pilot signal generated from the pilot signal generator 10 is connected.

The video head 2 is connected to a switch 30 for switching whether to select play or recording, and the recording signal comes from the adder 20.

In addition, a low pass filter 40 for detecting a pilot signal is connected to a luminance and color difference playback (Y = C PB) signal output terminal, and a reference REF to the low pass filter 40 and the pilot signal generator 10 is provided. The modulator 50 connects the pilot signal and the four pilot signals to 16 KHz and 46 KHz by the sum.

A band pass filter 60 for amplifying 16 KHz and 46 KHz is connected to the modulator 50 and a peak detector 70 for detecting a peak point of a signal level is connected to the band pass filter 60.

On the other hand, the peak detector 70 is connected to a comparator 80 for outputting an ATF error signal by comparing 16 KHz and 46 KHz, and a logic " high " state of a radio frequency (RF) switching pulse signal at an output terminal of the comparator 80. Connect a Sampling Hold 90 that is " turned on "

A unity-gain buffer 3 having a gain of 1 is connected to the sampling hold 90 (also referred to as a voltage follower), and a voltage level is supplied to the buffer 3. The reference value is set in between, and the lower value connects to Schmitt 100, which operates as logic "low" and the higher value as logic "high" to output the ATF lock signal.

In more detail, the pilot signal generator 10 configured as described above generates a pilot signal through the 1 / N divider 1 in the pilot signal generator 10 having an oscillation frequency fo of 5.9 MHZ, and the pilot signal is an adder. At 20, the luminance and color difference recording signals are added and output as recording signals.

On the other hand, when the switch 30 connected to the video head 2 is switched to the play side, the luminance and chrominance flyback signals are input to the low pass filter 40 having the cutoff frequency of 200 KHz to detect the pilot signal.

The signal is then input to the modulator 50 to sum or differ from the signal from the pilot signal generator 10 to produce 16 KHz and 46 KHz.

The 16 KHz and 46 KHz signals are input to the peak detector 70 through the band pass filter 60 to detect peak values of the signal levels.

In addition, the signal through the peak detector 70 is input to the comparator 80 and 16KHz and 46KHz are compared to output the ATF error signal in the waveform as shown in FIG.

On the other hand, a part of the signal output from the comparator 80 is output as a waveform of the signal as shown in (c) of FIG. 2 through the sampling and holding 90, and is input to the Schmitt 100 through the buffer 3 to the second The AFT lock signal is output in the waveform as shown in (d) of FIG.

If the ATF lock signal is in an advanced or delayed state such as (c) or (d) rather than the normal state as shown in FIG. In this case, the image quality deteriorates, and the radio frequency switching pulse signal and the ATF lock signal come back and forth in time.

That is, the present invention is to detect the phase difference as described above in slow control and to remove the noise component by adding or subtracting the tape feed amount during the next frame advance.

As mentioned above, this design adopts the ATF method for tracking, so that the pilot signal can be properly processed to detect the normal position even in the tape stop state, and the signal is output to the normal state with the ATF to solve the noise problem. It is designed to prevent the deterioration of image quality by obtaining the maximum reproduction output.

Claims (1)

A pilot signal generator 10 for generating a playback signal, an adder 20 connected to the pilot signal generator 10 for adding a luminance and chrominance recording signal and a pilot signal, and a video head 2 And a switch (30) for switching whether to record or play, comprising: a low pass filter (40) connected to a playback signal output and detecting a pilot signal connected to a playback signal output; A modulator (50) connected to the low pass filter (40) and the pilot signal generator (10) to make a reference pilot signal and four pilot signals by summation to 16 KHz and 46 KHz; A band filter (60) connected to the modulator (0); A peak value detector (70) connected to the band pass filter (60) for detecting peak points of signal levels; A comparator (80) connected to the peak detector (70) for outputting an ATF error signal by comparing 16 KHZ and 46 KHz; A sampling hold (90) coupled to the comparator (80) and " turned on " in a logic " high " state of a radio frequency switching pulse signal; A Schmitt (100) connected to the sampling hold (90) to schmid the sampled and held signal to produce an ATF lock signal; The ATF lock circuit of the 8mm video tape recorder is configured to further include.