KR100220603B1 - Skew compensating method in vcr - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a skew correction method of a video cassette recorder, and more particularly to skew caused by the position of a mechanical head on a head drum in a video cassette recorder having a multicast system. A skew correction method of a video cassette recorder for correcting a phenomenon.

The present invention is a multi-video cassette recorder having a PAL broadcast system and an NTSC broadcast system, and the head switching switching from the LP head to the SP head when the screen shift is performed when the drum broadcast method and the broadcast signal of the reproduced signal are different. If the drum is PAL broadcast and the signal being reproduced is NTSC broadcast, the signal is output 1.02㎲ late and if the drum is NTSC broadcast and the signal is PAL broadcast, 1.02㎲ is output faster. It is effective to correct the skew by shifting to a mechanism.

Description

How to Correct Skew of a Video Cassette Recorder

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a skew correction method of a video cassette recorder, and more particularly to skew caused by the position of a mechanical head on a head drum in a video cassette recorder having a multicast system. A skew correction method of a video cassette recorder for correcting a phenomenon.

As is well known, a video cassette recorder provided in each home has a recording function for recording a composite video signal applied from a tuner which tunes a broadcast signal received through an antenna to a desired channel, and a recording function for recording on a magnetic tape. Playback of the composite video signal and displaying it on a TV monitor.

Meanwhile, the color television broadcasting system can be classified into NTSC, PAL, and SECAM. Accordingly, the video cassette recorder is also classified into NTSC, PAL, and SECAM.

In this case, the NTSC (National Television System Committee) method is widely adopted mainly in Japan, the United States, Canada, and the like. The color signal, that is, the R, G, and B signals is converted into one luminance signal (Y) and two color differences ( I, Q) and then modulate a subcarrier with a frequency of 3.58 MHz in the video band with two color difference signals. The composite signal obtained by combining the modulated color difference signal and the luminance signal modulates and transmits a carrier having a higher frequency and has 525 scan lines.

On the other hand, PAL (Phase Alternation Line) method is adopted by Europe and China such as UK, Germany, Italy, Switzerland, and two-color right angle two-color subcarrier by two color difference signals BY and RY different from NTSC method. The modulated signal is transmitted in addition to the luminance signal by inverting its polarity by 180 ° per scan line 1H. The receiving side reproduces the color difference signal by the sum and difference of the color difference signals. In the PAL method, the number of scanning lines is 625, whereas the number of scanning lines is 525, which is called the PAL-M method.

Recently, a video cassette recorder having a multi-color broadcast system as described above has appeared. Such a multi-color broadcast system includes an LP head and an SP head as shown in FIG. 2A. The distance is fixedly 2H apart, and both NTSC and PAL methods are available.

At this time, the multiple color broadcast system reads and reproduces the noise portion generated when the special reproduction mode is performed by the LP head, and reads the normal signal by the SP head.

However, as described above, the multiple color broadcasting system is fixedly mounted at a distance of 2H apart from the distance between the LP head and the SP head. Thus, when the video cassette recorder is played back, for example, the recording is performed at the standard speed (SP) of the NTSC method. When the drum is in the PAL mode when reproducing the signal, or when the drum is in the NTSC mode when playing the signal recorded in the standard speed (SP) of the PAL method, the screen shifting, that is, at the time of switching from the LP head to the SP head, As described above, there is a problem that a skew phenomenon occurs due to an error caused by the head spacing, ie, a skew phenomenon caused by the horizontal synchronization, that is, the upper part of the screen is bent in the horizontal direction.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and an object of the present invention is to generate a screen shift when a drum broadcast method and a broadcast method of a reproduced signal are different in a video cassette recorder having a multi-color broadcast system. A skew correction device of a video cassette recorder for correcting a skew phenomenon is provided.

A feature of the present invention for achieving the above object is a skew correction method of a multi-cast video cassette recorder capable of recording and reproducing signals of NTSC broadcast and PAL broadcast methods. Detecting a drum drive broadcasting method of the video cassette recorder; A reproduction signal broadcast method detecting step of detecting a broadcast method of a signal reproduced by the video cassette recorder; A screen shift mode performing key signal provision determining step of determining whether a key signal for shifting the screen speed of the video cassette recorder is provided; And a skew correction step of selectively providing a head switching pulse corresponding to a result of the drum driving broadcast method detection step and the reproduction signal broadcast method detection step when the screen shift mode execution key signal is provided to correct the skew. do.

The above objects and various advantages of the present invention will become more apparent from the preferred embodiments of the invention described below with reference to the accompanying drawings by those skilled in the art.

1 is a block diagram showing the configuration of a skew correction apparatus of a video cassette recorder according to a preferred embodiment of the present invention;

2 is a view showing a mounting state and a switching pulse waveform of a general head,

3 is a flowchart for performing a skew correction method of a video cassette recorder according to the present invention.

* Explanation of symbols for main parts of the drawings

10: key input unit 20: micom

30: deck unit 40: video signal processing unit

50: OSD part

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

1 is a block diagram showing a configuration of a skew correcting apparatus of a video cassette recorder according to the present invention, in which a key input unit 10 for providing a predetermined key signal pressed by a user and a predetermined key provided in the key input unit 10 are provided. Provides deck control signals corresponding to the signals, provides horizontal synchronization and envelope comparison signals, control signals corresponding to capstan PG signals, and controls on-screen display (OSD) characters The microcomputer 20 for providing a signal, the deck unit 30 for recording a signal provided according to the deck control signal provided from the microcomputer 20 as a mechanical mechanism, and reproducing and providing the recorded signal, the deck unit 30. An image signal processor 40 and an image processing and providing image signal provided by the and providing a horizontal synchronization and envelope comparison signal to the microcomputer 20 from the provided image signal Mixing the character that corresponds to the five SD character control signal supplied from the video signal and a microcomputer 20 provided in the call control and is composed of five SD section 50 provided in the monitor.

A detailed description of the operation of the skew correcting apparatus of the video cassette recorder according to the present invention configured as described above is as follows.

The key input unit 10 is composed of a key matrix, and provides a signal for a predetermined key signal key signal pressed by a user, that is, a playback key and a special mode execution key, that is, a screen shift key, to the microcomputer 20.

At this time, the microcomputer 20 provides a deck control signal to the deck unit 30 to drive the deck unit 30 in the play mode when a signal for the playback key is provided from the key input unit 10, and the deck unit ( 30 corresponds to a deck control signal provided by the microcomputer 20 in a playback mode, and provides a video signal to be played back to the video signal processor 40.

In addition, when the signal for the screen shift key is provided from the key input unit 10, the microcomputer 20 provides the deck control signal thereto to the deck unit 30. At this time, the deck unit 30 performs the screen shift mode in response to the deck control signal provided from the microcomputer 20 and provides the microcomputer 20 with data of a broadcasting method of the drum currently being driven. That is, the microcomputer 20 decks the head switching signal and the switching signal based on the driving broadcast method of the provided drum and the broadcast method data of the reproduced signal provided from the image signal processing unit 40 as described below. Provided to section 30.

In other words, the microcomputer 20 switches the switching pulses and the SP heads to switch the R and L channels of the LP head as shown in FIG. 2 by the vertical synchronization of the FG of the capstan and the image signal processor 40 (not shown). A switching pulse for switching the R channel L channel is provided to the deck unit 30.

At this time, when the signal for the screen shift mode execution key is provided from the key input unit 10, the microcomputer 20 is provided by the image signal processor 40 when the driving broadcast method of the drum and the broadcast method of the reproduced signal are the same. The head switching pulse, that is, the head switching signal for switching from the LP head to the SP head, is provided to the deck unit 30 according to the synchronization and envelope comparison signals, and if the driving broadcast method of the drum and the broadcast method of the reproduced signal are not the same, When the drum is a PAL broadcast system and the signal being reproduced is an NTSC broadcast signal, the switching signal is output 1.02 ms late. When the drum is an NTSC broadcast system and the signal being reproduced is a PAL broadcast system, the switching signal is output 1.02 ms fast.

Therefore, the deck unit 30 is driven according to the switching pulse and the head switching pulse provided from the microcomputer 20 to reproduce the recorded signal and provide it to the image signal processing unit 40.

At this time, the image signal processing unit 40 processes the image signal reproduced from the deck unit 30 and provides the image signal to the OS 50, and provides the horizontal synchronization and the envelope to the microcomputer 20 as described above. do.

On the other hand, the OS unit 50 mixes the image signal provided from the image signal processor 40 and the OSD character corresponding to the OSD character control signal provided from the microcomputer 20 and outputs it to the monitor.

3 is a flowchart for performing a skew correction method of a video cassette recorder according to the present invention, which will be described in detail with reference to the block diagram shown in FIG.

When the deck unit 30 is driven in the regeneration mode in step 300, the microcomputer 20 detects whether the drum of the deck unit 30 is driven by the drum broadcast, that is, the PAL method or the NTSC method. Proceed to step. At this time, if the driving broadcast method of the drum detected in step 301 is a PAL method, the microcomputer 20 proceeds to step 303 to detect a broadcast method of a signal provided from the image signal processor 40.

That is, if the broadcast method of the signal provided from the video signal processor 40 is an NTSC broadcast signal (step 304), the microcomputer 20 proceeds to step 305, and the signal provided from the video signal processor 40 If the broadcast method is not a signal of the NTSC broadcast method, the flow proceeds to step 306 to control the deck unit 30 to perform the previous mode.

The microcomputer 20 proceeds to step 305 and determines whether a signal for the screen shift mode execution key is provided from the key input unit 10. As a result of determination, when the signal for the screen shift mode execution key is provided from the key input unit 10, the microcomputer 20 takes the time for switching the head switching switching signal from the LP head to the SP head in the PAL broadcasting method. Delayed by 1.02 ms, that is, delayed by 1.02 ms, and outputted to the deck unit 30, proceeding to step 308, and performing the screen shift mode from the key input unit 10 in the NTSC broadcasting system. If no signal is provided for the key, the flow proceeds to step 306.

Therefore, the deck unit 30 is delayed by 1.02 ms of a head switching pulse provided from the microcomputer 20 to switch from the LP head to the SP head.

On the other hand, if the drive broadcast method of the drum detected in step 302 in step 302 is not a PAL method, the microcomputer 20 proceeds to step 309 because the currently driven drum drive method is an NTSC method. ) Detects a broadcast method of the video signal reproduced in the "

That is, if the broadcast method of the video signal reproduced by the video signal processor 40 detected in step 309 is a PAL method, the microcomputer 20 proceeds to step 311 and broadcasts the video signal reproduced by the video signal processor 40. If the method is not the PAL method, the flow proceeds to step 306.

In this case, the microcomputer 20 determines whether a signal for the screen shift mode execution key is provided from the key input unit 10 in step 311. When the signal for the screen shift mode execution key is provided, the microcomputer 20 proceeds to step 312. If a signal for the screen shift mode execution key is not provided, the flow proceeds to step 306.

The microcomputer 20 proceeds to step 312. The time required for switching the head switching signal from the LP head to the SP head when the drum drive broadcasting method is switched from the LP head to the SP head in the PAL broadcasting method and the NTSC broadcasting method is determined. As soon as the difference in time taken from the LP head to the SP head is changed, that is, 1.02 ms, it is outputted to the deck unit 40 and the flow proceeds to step 308.

As described above, when the drum broadcasting method and the broadcast method of the reproduced signal are different in the skew correction method of the video cassette recorder according to the present invention, that is, the multiple video cassette recorder having the PAL broadcast method and the NTSC broadcast method system, screen shift is performed. When the drum switches from the LP head to the SP head and outputs the head switching signal to the PAL broadcast method and the reproduced signal is the NTSC broadcast signal, the output is 1.02 1.0 later and the drum is the NTSC broadcast method and the reproduced signal is the PAL broadcast method. In this case, since the output speed is 1.02 kHz, the speed is shifted to the same broadcasting mechanism, thereby correcting the skew.

While the invention has been shown and described with respect to certain preferred embodiments, it will be apparent to those skilled in the art that various modifications, changes and omissions can be made without departing from the spirit and scope of the invention.

Claims (4)

A skew correction method of a multi-cast video cassette recorder capable of recording and playing back signals of NTSC broadcasting and PAL broadcasting, A drum driving broadcast method detecting step of detecting a drum driving method of the video cassette recorder when the video cassette recorder is in a playback mode; A reproduction signal broadcast method detecting step of detecting a broadcast method of a signal reproduced by the video cassette recorder; A screen shift mode performing key signal provision determining step of determining whether a key signal for shifting the screen speed of the video cassette recorder is provided; And And a skew correction step of selectively providing a head switching pulse corresponding to a result of the drum driving broadcast method detecting step and the reproduction signal broadcasting method detecting step when the screen shift mode execution key signal is provided to correct the skew. Skew correction method of video cassette recorder. The method of claim 1, wherein the head switching pulse is a switching pulse for switching from the LP head to the SP head. The method of claim 1, wherein the skew correcting step comprises: the drum drive broadcast method detected in the drum drive broadcast method detecting step is the PAL method and the playback signal broadcast method detected in the playback signal broadcasting method detecting step is the NTSC broadcasting method. The difference between the time taken when the drum driving broadcast method is switched from the LP head to the SP head in the PAL broadcasting method and the time taken when the head switching pulse is switched from the LP head to the SP head in the NTSC broadcasting method Skew correction method for a video cassette recorder characterized in that the delay is provided as much as possible. The method of claim 1, wherein the skew correction step comprises: the drum drive broadcast method detected in the drum drive broadcast method detection step is the NTSC method and the playback signal broadcast method detected in the playback signal broadcast method detection step is the PAL broadcast method. Is a difference between the time taken when the drum drive broadcasting system switches from the LP head to the SP head in the PAL broadcasting system and the time taken when switching from the LP head to the SP head in the NTSC broadcasting system. Skew correction method of a video cassette recorder, characterized in that providing as fast as the corresponding time.

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