KR930009686B1 - Track jump circuit of laser disk player - Google Patents

Abstract

This is about a laser disk player, specially about a track jump circuit of laser disk player to remove the heating phenomenon of screen in track jump when constant linear velocity laser disk is playing. The circuit comprises a switch to block the video output signal recorded in track jump, a generating means of gray video signal for generating reference signal to output gray video signal through the switch, and a comparing means to replay normally the vertical synchronization signal including a vertical synchronization signal and a gray video signal by signal difference.

Description

Track jump circuit of laser disc player

1 is a conventional track jumping circuit diagram.

2 is a track jumping circuit diagram of a laser disc player according to the present invention.

3 and 4 are diagrams illustrating signal waveforms of the operation state of the laser disk player and the corresponding parts of FIG. 2.

* Explanation of symbols for main parts of the drawings

1: Source of tracking error signal 2: Tracking servo device

4, 40: tracking logic circuit 13: comparator

4: reference signal generator 15: crystal oscillator

16: gray video signal generator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to laser disc players, and more particularly to a track jump circuit of a laser disc player for eliminating the degradation of a screen during track jump during the playback of a constant linear velocity laser disc.

In the conventional laser disc player, the tracking jump circuit is configured as shown in FIG. 1. The tracking error signal detected by the tracking error signal sensor 1 during normal playback is transmitted to the tracking servo circuit 2 to be switched. It is applied to the tracking coil 3 via SW ₁ . On the other hand, when the track search button FF or FB is pressed, a signal for this is input to the tracking logic circuit 4, and the tracking error signal generated by the tracking error signal sensor 1 is digitally displayed by the waveform shaper 5. The waveform is waveform-formed and input to the tracking logic circuit 4. The track logic circuit 4 and the woman transfer signal generator (6), provides a switch control signal (CTL ₁₎ to (SW ₁₎ to thereby switch the switch (SW ₁₎ to the contact point ⓑ from ⓐ engaged. Then, the tracking transfer signal generated by the transfer signal generator 6 is applied to the tracking coil 3 to perform the tracking jump.

However, since the conventional tracking jump circuit performs track jump regardless of the synchronization of the video signal, there is a problem in that the synchronization of the screen occurs when tracking during the playback of the laser disk of the fixed speed method.

Therefore, the present invention has been made in view of the above situation, and the tracking period of the laser disk player for eliminating the synchronous collapse of the screen by outputting a gray screen and outputting a playback screen when the track jump is over and the synchronization is stabilized. The purpose is to provide a jump circuit.

In order to achieve the above object, the present invention provides a track jump circuit of a video laser disc player, the switch for cutting off a video output signal reproduced at the time of track jumping, and generating a reference signal to output a gray video signal through the switch. Comparing the gray video signal generating means with the vertical sync signal of the video signal being reproduced and the vertical sync signal included in the gray video signal to operate the above-mentioned switch that is blocked when these signals match. It was made by the comparison means.

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

2 is a track jump circuit diagram of a laser disc player according to the present invention, in which reference numerals similar to those of the first and second parts indicate similar parts.

The signal FM read from the pickup (not shown) during normal reproduction of the right-hand image is demodulated by the demodulator 10 and then filtered by the low pass filter 11 to monitor as a reproduced video signal through the switch SW ₂ . (Not shown). At this time, the switch SW ₂ is located at the contact point ⓐ under the control of the control signal ctl ₂ of the tracking logic circuit 40, and the switch SW ₁ also controls the control signal CTL ₁ of the tracking logic circuit 40. Is located at contact point ⓑ (see waveforms in Figure 3 (f) and (g)).

On the other hand, the video signal passing through the low-pass filter 11, the vertical synchronization signal is separated by the vertical synchronization signal separator 12 as shown in Fig. 3 (d) and input to the comparator 13.

The reference signal generator 14 generates a reference signal by the operation of the crystal oscillator 15, inputs a vertical synchronization signal to the comparator 13, and inputs the reference video signal to a video signal (gray screen signal) generator 16. ) Is applied.

By the way, when the user presses the track search butt (FF or FB) at time T ₁ in the waveform of FIG. 3 (h) to search for the track during normal playback, the control signal CTL ₁ of the tracking logic circuit 40 is detected. (CTL ₂ ) are all high, so switch SW ₁ and switch SW ₂ are connected to contact ⓑ.

At this time, when the first (after T ₁ ) vertical synchronization signal of the vertical synchronization signal of the reproduction synchronization signal of FIG. 3 (d) is detected, the switches SW ₁ and SW ₂ are connected to the contact ⓑ to perform the tracking jump. . When the track jumps, the tracking logic circuit 40 excites the feed signal generator 6, and accordingly, the feed signal generator 6 generates a feed signal as shown in FIG. The acceleration and deceleration pulses are divided into intervals, and the interval is the number of pulses in FIG. 4 (c) obtained by waveform-shaping the tracking error signal (FIG. 4 (b)). As shown in FIG. 4A, in the tracking logic circuit 40, the acceleration section τ ₁ is performed for 2 tracks during the 4 track jump, and the deceleration section τ ₂ is performed for 2 track jumps.

The switch SW ₂ is connected to the ⓑ contact point when the track jump is completed. When the track jump is completed, the tracking logic circuit 40 returns only the switch SW ₁ to the ⓐ contact point using the control signal CTL ₁ . In playback mode, the video signal displayed on the monitor becomes a gray screen.

At this time, the comparator 13 compares the synchronization of the original video signal to be reproduced (FIG. 3 (d)) with the synchronization of the reference signal (FIG. 3 (E)) and matches the tracking logic circuit 40 if they match each other. When the signal is applied, the tracking logic circuit 40 causes the switch SW ₂ to be returned from the contact ⓐ using the control signal CTL ₂ , so that the original video screen to be reproduced is displayed on the monitor.

The present invention which operates as described above has a feature that the jumping period during the track jump outputs a gray screen and outputs a playback screen when the jump is completed and the synchronization is stabilized, thereby preventing the synchronization collapse of the screen.

Claims (2)

In the tracking jump circuit of video laser disc play; A switch SW _{2 for} receiving a reproduced video signal output from the low pass filter 11 at the track jump through the contact point a; A video channel generator 16 for outputting a gray video signal to the contact point b of the switch SW ₂ according to a reference signal from the reference signal generator 14; A comparator for comparing the vertical synchronization signal of the reproduced video signal input from the synchronization signal separator 12 with the vertical synchronization signal of the gray video signal from the reference signal generator 14 and outputting a match to the tracking logic circuit 40. And a tracking logic circuit 40 for outputting a control signal CTL ₂ to the switch SW ₂ while receiving an output of the comparator 13 and a signal of an external trackwatch button. Track jump circuit of a laser disc player. The method of claim 1, wherein the switch of the by video signal generator 16 of the generates a gray video signal using the reference signal input from reference signal generator 14 by the operation of the crystal oscillator (15), (SW ₂ The track jump circuit of the laser disc player, characterized in that selectively output through.

Images