KR20000038233A - Device for compensating drop-out of vcr - Google Patents

Abstract

PURPOSE: A compensator of drop-out in a VCR is provided to enlarge a compensating range of drop-out and to restore an exact restoring signal inside a drop-out section by using a field memory. CONSTITUTION: An output of an AGC(Auto Gain Control) unit(22) contains a drop-out section. A detecting unit of drop-out(23) outputs a detecting pulse of drop-out by detecting the drop-out in a restoring FM signal. An extracting unit of signal(26) controls a drop-out compensation by receiving the detecting pulse of drop-out from the detecting unit of drop-out(23). An output of a field memory(25) is controlled to output a signal corresponding to a part generated the drop-out among signals stored in the field memory(25) by converting to a digital signal through an A/D converting unit(24) and the output of the field memory(25) is outputted in an analog signal by passing a D/A converting unit(27). An output of the D/A converting unit(27) is compensated the drop-out and outputted by adding with the output of the AGC unit(22) in an adding unit(28).

Description

VSI's Drop Out Compensator

The present invention relates to a drop out compensation device of a VCR. More particularly, the present invention relates to a drop out compensation device of a VCR that enables the restoration of an accurate playback signal within an extension of a dropout compensation range and a dropout period using a field memory. It is about.

A VCR is an electronic device having a function of recording a signal provided from various regular broadcast programs or an external video source on a video tape or playing back through a TV receiver. FIG. 1 is a schematic block diagram of a general VCR system. .

It is connected to the microcomputer (1) for controlling the overall VCR system deck unit (2) for performing the deck operation for recording / playback under the control of the microcomputer (1), the microcomputer (1) and the deck unit ( 2), the servo unit 3 for controlling the drive motor and the like on the deck unit 2 side is connected.

In addition, the microcomputer 1 and the deck unit 2 include amplification, drop-out compensation, FM demodulation, and the like, which are reproduced through the deck unit 2 under the control of the microcomputer 1. The video signal processor 4 to be connected is connected.

The microcomputer 1 and the video signal processor 4 are connected to an OSD unit 5 for generating an OSD (On Screen Display) screen under the control of the microcomputer 1, and to the video signal processor 4. In order to send the output of the video signal processing unit 4 to the TV receiver 7, a modulator 6 for modulating an RF signal is connected, and the TV receiver 7 is connected to the modulator 6.

In addition, the microcomputer 1 is connected to a key input unit 8 for inputting various keys together with a remote controller transmitter, and a display unit 9 for performing various types of display including time and channel display, and from the antenna ANT of the VCR system. A tuner 10 for receiving a regular broadcast signal and performing channel tuning is connected to the microcomputer 1 and the video signal processor 4.

In such a VCR system, the tape reproduction signal reproduced through the deck unit 2 is output by the video signal processing unit 4 through amplification, dropout compensation, FM demodulation, and the like, and the dropout compensation of the video signal processing unit 4 is performed. This will be described in detail below.

If there is an OSD screen generated by the OSD unit 5, the OSD screen signal is also output. The output of the video signal processor 4 is converted into an RF signal through the modulator 6, and then the TV receiver 7. Is output.

In the normal broadcast signal recording, the video signal processor 4 processes the normal broadcast signal input to the tuner 10 through the antenna ANT and records the signal through the deck unit 2.

Drop out refers to a phenomenon in which the FM signal is lost during playback read out from the head due to tape breakage, deterioration, foreign matter on the head, foreign matter on the deck running system, and the like, and the video signal processor 4 performs dropout compensation.

Dropout compensation inserts a signal before 1H (one horizontal scanning period) in a portion where dropout has occurred, which will be described with reference to FIG. 2 which shows a block diagram of a dropout compensation circuit in the video signal processor 4.

When a dropout occurs in the reproduction FM signal, a defective portion as shown in A of FIG. 3 occurs in the reproduction FM signal, and the reproduction FM signal is inputted to the dropout detection unit 4b via the limiter 4a to be connected to B of FIG. The same drop out detection pulse is output.

A 1H delay unit 4d for delaying the reproduction FM signal by 1H is connected to the output, and the switch 4c is switched to the 1H delay unit 4d according to the dropout detection pulse output from the dropout detection unit 4b. As shown in C of FIG. 3, the 1H delayed signal is output.

Since the 1H delayed signal is a signal that is exactly 1H delayed before the dropout occurs, the 1H delayed signal can be compensated inconspicuously even if it is moved to the dropout portion.

In addition, since the 1H delay unit 1d is closed-circuit with respect to the output, the 1H delay unit 1d is changed to the signal before 1H repeatedly and corrected even for a dropout of 1H or more period.

However, since the drop-out compensation circuit only compensates up to 10H, in the case of the 20H signal dropout as shown in FIG. 3, compensation is possible due to the signal repetition before 1H only up to 10H, and the period after 10H appears in white.

That is, in the conventional dropout compensation circuit, only the section up to 10H can be dropped out, but even this section cannot be correctly restored due to the repetition of the same signal, and there is a problem that the section after 10H is not compensated. .

The present invention is to solve this problem, the present invention is to store the reproduction FM signal for one field in the field memory during the drop-out compensation, and the corresponding among the signals stored in the field memory when the drop-out detection from the input reproduction FM signal It is an object of the present invention to provide a dropout compensation device of a VCR that allows the signal of the section to be output so that the original signal can be restored as much as possible without being affected by the length of the dropout section.

1 is a schematic block diagram of a general VCR system

FIG. 2 is a detailed block diagram of a dropout detection circuit in the video signal processor of FIG. 1. FIG.

3 is a waveform diagram of each part of the dropout detection circuit of FIG. 2;

4 is a block diagram of a drop out compensation device of a VCR according to the present invention;

5 is a waveform diagram of each part of FIG. 4.

* Description of the symbols for the main parts of the drawings *

21: preamplifier 22: AGC unit

23: drop out detection unit 24: A / D conversion unit

25: field memory 26: signal extraction unit

27: D / A converter 28: Adder

The drop out compensation device of the VCR according to the present invention for achieving this object detects the drop out of the reproduction FM signal from the output of the AGC unit in the drop out detection unit, and converts the output of the AGC unit into a digital signal in the A / D conversion unit. The drop out detection unit stores a signal of a field immediately before the field in which the drop out detection unit detects a drop out of the output of the A / D converter, and outputs the dropout detection pulse when the dropout detection unit outputs the dropout detection unit. Extract the corresponding signal from the field memory, and convert the extracted signal into an analog signal in the D / A converter and add it to the output of the AGC unit in the adder so that the dropout is compensated for and outputted. By using it, it is possible to enlarge the drop out range and restore the original signal as much as possible.

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

4 is a block diagram of a drop out compensation device of a VCR according to the present invention.

As shown in the drawing, an AGC (Auto Gain Control) unit 22 is connected to a preamplifier 21 for amplifying a reproduction FM signal reproduced by a head (not shown).

The AGC unit 22 is connected to a dropout detection unit 23 that receives the output signal of the AGC unit 22 and detects the dropout of the reproduction AF signal and outputs a dropout detection pulse upon detecting the dropout.

In addition, the AGC unit 22 is connected with an A / D conversion unit 24 for converting the reproduction FM signal output of the AGC unit 22 into a digital signal, and the A / D conversion unit 24 is connected to A / D. The field memory 25 is connected to the reproduction FM signal of the field immediately before the field in which the dropout detection unit 23 detects the dropout during the output of the D conversion unit 24.

When the dropout detection pulse 23 outputs the dropout detection pulse, the signal extraction unit 26 outputs a signal corresponding to a portion of the reproduction FM signal stored in the field memory 25 where the dropout detection pulse is generated. ) Is connected to the dropout detector 23 and the field memory 25.

In addition, the field memory 25 is connected to a D / A converter 27 for converting a reproduction FM signal output from the field memory 25 into an analog signal.

The AGC unit 22 and the D / A converter 27 add the output of the D / A converter 27 and the output of the AGC unit 22 to output a reproduction FM signal compensated for dropout. The adder 28 which outputs to a signal processing part is connected and comprised.

Here, the video signal processor is a block configured to perform a process after the dropout compensation block among blocks of the general video signal processor.

In the present invention configured as described above, the preamplifier 21 amplifies the reproduced FM signal reproduced by the head, and the output of the preamplifier 21 is input to the AGC unit 22 which makes the signal size constant and the signal. The size is fixed and output.

The output of the AGC unit 22 is input to the dropout detector 23 to detect a dropout. When the dropout is detected, the dropout detector 23 sends a dropout detection pulse to the signal extractor 26. Output

On the other hand, the output of the AGC unit 22 is also input to the A / D conversion unit 24 is converted into a digital signal and stored in the field memory 25.

At this time, the field memory 25 stores a signal one field earlier than the signal input to the dropout detection unit 23.

Accordingly, when the dropout detection pulse 23 outputs the dropout detection pulse, the signal extractor 26 may be a signal corresponding to a portion of the signal stored in the field memory 25 where the dropout detection pulse is detected, that is, one field. Causes the previous signal to be output.

The output of the field memory 25 is inputted to the D / A converter 27 to be converted into an analog signal, and then inputted to the adder 28 to be added to the output of the AGC unit 22 to drop out. This is compensated and output to the video signal processor.

The operation of the present invention will be described with reference to the waveform diagram of FIG. 5 as follows.

First, when the output of the AGC unit 22 includes a dropout period of about 20H as shown in FIG. 5A, the dropout detection unit 23 detects that there is a dropout in the reproduction FM signal, and thus, FIG. A drop out detection pulse such as B is output.

When the dropout detection pulse outputs from the dropout detection unit 23, the signal extractor 26 receives the input to control dropout compensation.

That is, the output of the field memory 25 is controlled so that a signal corresponding to the portion where the dropout has occurred is converted into a digital signal through the A / D converter 24 and stored in the field memory 25. In addition, the output of the field memory 25 is output as an analog signal via the D / A converter 27, as shown in C of FIG.

The output of the D / A converter 27 is added by the output of the AGC unit 22 and the adder 28 to compensate for the dropout as shown in FIG. 5D.

In the above, the signal extractor 26 may allow the microcomputer that is generally configured in the VCR to perform its function.

In addition, the present invention is to configure the drop-out compensation circuit of the video signal processing unit of the general VCR of the respective parts (23-28), so that when the drop out occurs, the signal before one field is outputted so that the drop out is compensated.

As described above, according to the dropout compensation apparatus of the VCR according to the present invention, when the dropout occurs, the dropout compensation is performed by a signal before the one field stored in the field memory so that the dropout period is not affected. Therefore, the original signal can be restored as much as possible.

Claims (1)

A VCR system comprising a preamplifier 21 for amplifying a reproduced FM signal reproduced by a head and an AGC unit 22 for making the output signal of the preamplifier 21 constant. A drop-out detector 23 for detecting a drop-out of the reproduction FM signal by receiving the output signal of 22) and outputting a drop-out detection pulse at the time of the drop-out detection; and converting the output of the AGC unit 22 into a digital signal. A field memory 25 in which an A / D converter 24 and a signal corresponding to a field immediately before a field for detecting the dropout by the dropout detector 23 among the outputs of the A / D converter 24 are stored. And a signal extractor 26 for outputting a signal corresponding to a portion of the dropout detection pulse generated in the field memory 25 when the dropout detection pulse is output from the dropout detection unit 23. Convert the output signal of the memory 25 to an analog signal Consists of a D / A converter 27, an adder 28 for adding the output of the AGC unit 22 and the output of the D / A converter 27 to output a signal compensated for dropout. Dropout compensation device of the VCR characterized in that.