KR0181071B1 - Method for tracking track in a video cassette recorder - Google Patents

Abstract

The present invention relates to a tracking method of V-Cal. More specifically, when the head width is wider than the track pitch during self-rusting, it is possible to control the phase of the control signal corresponding to the head switching to track the V-Cal as in recording. To a tracking method.

According to the present invention, after performing auto tracking during self-rusting, the phase of the playback CTL is traced by tracking (head width-track pitch) / 2 at the tracking center, so that the boundary of the screen when the head width is wider than the track pitch is obtained. It is effective to maintain the clearer picture quality by preventing noise generated in the.

Description

METHOD FOR TRACKING TRACK IN A VIDEO CASSETTE RECORDER

1 is a block diagram of a tracking device of a video cassette recorder according to the present invention;

2 shows a track pattern during tracking of a video cassette recorder according to a preferred embodiment of the present invention.

3 is a flowchart for performing a tracking 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: head width detection unit 40: CTL head

50: drum servo system 60: capstan servo system

The present invention relates to a tracking method of a video cassette recorder (hereinafter referred to as VCS), and more particularly, to perform auto tracking during self-burning. A tracking method of V-Cal for tracing in position.

In general, a video signal of a video cassette recorder is recorded in a straight line inclined on the tape surface by winding a tape on a rotating drum, that is, in a helical scan method. Therefore, at the time of reproduction, noise is generated if the timing of the drum rotation and the timing of the tape movement do not match. Therefore, auto tracking is required to match the track of the rotating head and the track of the track recorded inclined. In other words, in the case of VHS, auto tracking reproduces the control signal recorded in the control track at the bottom of the tape and traces the track so that the maximum envelope value is detected as a reference signal. Ensure that the relationship is the same as at recording.

At this time, the track pitch is usually constant because it is determined by the VHS standard. However, since the head width varies between manufacturers, the head width is often larger than the track pitch defined by the VHS standard. That is, the track pattern in the case of recording by a head having a head width wider than the track pitch is formed as shown in FIG.

At this time, when recording and reproducing by a head having a head width wider than the track pitch as shown in FIG. 2A, that is, when self-recording and auto tracking are performed, the head position at the time of recording is out of the head. The position to be traced is shifted from the recording time.

Therefore, noise is generated at the edge of the color on the screen, resulting in a deterioration of the image quality.

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 set the phase of a reproduction CTL in a tracking center (head width in response to head switching when the video head width is wider than the track pitch). By tracking by track pitch) / 2, the present invention provides a tracking method of V-Cal to maintain a clearer image quality by preventing noise generated at the boundary of the screen during magnetic recording.

The method according to the present invention for achieving the above object is a control method of a video cassette recorder for controlling the rotational phase of the head using the control signal as a reference signal and tracking the positional relationship between the tape and the head as in recording. Determining whether a signal for a reproduction mode key is input; When the signal for the regeneration mode key is input, the track width according to the head width and the traveling speed mode is detected. If the detected head width is larger than the track pitch, the heading center corresponds to (Head Width-Track Pitch) / 2 in response to head switching. Leading the phase of the control signal.

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

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

1 is a block diagram of a video cassette recorder for performing tracking according to the present invention. The key input unit 10, the microcomputer 20, the head width detector 30, the CTL head 40, the drum servo system 50 are shown in FIG. ) And the capstan servo system 60.

The key input unit 10 is configured to normally output key signals pressed by the user by being composed of key metrics to the microcomputer 20.

At this time, the microcomputer 20 outputs a control signal corresponding to the predetermined key signal output from the key input unit 10. When the signal for the regeneration mode key is input from the key input unit 10, the microcomputer 20 heads. The track width of the tape according to the traveling speed mode of the tape is detected by determining the traveling speed mode of the tape and the head width data input from the head width detector 30 which detects the width and outputs it to the microcomputer 20.

That is, the microcomputer 20 performs auto tracking so that the maximum envelope value is detected during playback, and compares the head width and track pitch relationship. When the head width is wider than the track pitch, the microcomputer 20 controls the rotation of the head servo system ( Auto-tracking by controlling the CTL head 40 to lead the CTL phase by (Head Width-Track Pitch) / 2 at the tracking center, i.e. at the position of the largest envelope value, in response to the head-switched switching pulse output to 50). And then trace at the same position as the recorded head position, i.e., the recording position as shown in (a) of FIG.

In addition, the microcomputer 20 controls the capstan servo system 60 to correspond to the phase of the CTL read by (head width-track pitch) / 2 at the position of the maximum envelope value as described above.

At this time, the drum servo system 50 switches the video heads mounted on both sides of the drum according to the head switching pulses output from the microcomputer 20 as described above to trace the video tracks, and the capstan servo system 60 is the microcomputer. The tape traveling speed is controlled so as to correspond to the control signal output from the 20.

3 is a flowchart for performing a tracking method of VR in accordance with the present invention.

First, the microcomputer 20 determines whether a signal for the playback mode key is input in step 300.

As a result of the determination, when a signal for the regeneration mode key is input, the microcomputer 20 proceeds to step 301, and terminates when a signal for the regeneration mode key is not input.

The microcomputer 20 proceeds to step 301 and detects the head width and the traveling speed mode input from the head width detector 30 to detect the track pitch according to the detected travel speed mode (step 302), and step 303. Proceed to

In step 303, the microcomputer 20 compares the head width detected in step 301 with the width of the track pitch detected in step 302.

As a result of the comparison, if the head width is wider than the track pitch, the process proceeds to step 404, and if the head width is not wider than the track pitch, the process ends.

That is, the microcomputer 20 reads the phase of the CTL by the tracking center (head width-track pitch) / 2 in response to head switching in step 404.

For example, when the color broadcast method is NTSC, the tape running mode is EP (Extended Play) mode, the head width input from the head width detector 30 is 26 μm, and the track pitch according to the EP mode is 19.2 μm, The phase lead value of the CTL is calculated as follows by the above-described formula, i.e. (head width-track pitch) / 2.

Since the value of (26-19.2) / 2 = 3.4 mu m is obtained, the phase of the CTL corresponding to the head switching pulse is read from the tracking center by [3.4 mu m / 19.2 x 2] x 33.3 mu s (30 mu s) = 2.94 mu s.

That is, the microcomputer 20 controls the CTL head 40 to read and output the phase of the CTL by 2.94 kHz in response to the switching pulse output to the drum servo system 50, so that the head at the originally recorded position is reproduced. Control tracing.

Therefore, during playback, if the head is raised and traced by (head width-track pitch) / 2, i.e., (a) shown in FIG. 2, at the position where the maximum envelope value is detected, The trace is traced in the same way as the track pattern, and no boundary noise is generated.

As described above, in the tracking method of V-Cal according to the present invention, the head width is performed by performing the trace by leading the phase of the reproduction CTL (Control) by (head width-track pitch) / 2 at the tracking center. If the track pitch is wider than this, the noise generated at the boundary of the screen is prevented, thereby maintaining a clearer picture quality.

While the invention has been shown and described with respect to certain preferred embodiments, those skilled in the art will recognize that various modifications and changes can occur without departing from the spirit and scope of the invention as set forth in the claims below.

Claims (1)

In a tracking method of a video cassette recorder in which a control signal is used as a reference signal to control the rotational phase of the head and tracking the positional relationship between the tape and the head, it is determined whether a signal for the playback mode key is input. Step 300; When the signal for the regeneration mode key is input, the track width according to the head width and the traveling speed mode is detected. If the detected head width is larger than the track pitch, the heading center corresponds to (Head Width-Track Pitch) / 2 in response to head switching. And tracking the phases of the control signals (301 to 304).