KR970000154B1 - Auto-control method of optimum position tracking - Google Patents

Abstract

The method is provided for automatically searching an optimal tracking position by using envelopes of video and audio, and comprises the steps of; detecting a video envelope(first detector); detecting a Hi-Fi audio envelope(second detector); controlling/putting out a serial data, a digital tracking control signal and a tape speed control signal(micom); receiving the signal data to operate the tape(server); receiving the serial data, the tracking control signal and the speed control signal from a micom and receiving a head switching pulse and a control pulse from a server to generate a tracking shift signal to the micom(digital tracking controller); detecting the envelope of audio and video to control the tracking to the optimal position automatically.

Description

Automatic location tracking control method

1 is a block diagram of the present invention.

2 is an operational waveform diagram according to the present invention.

3 is a flow chart of the present invention.

4 is a tracking optimum point determination graph.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of controlling tracking misalignment in a video tape recorder (hereinafter referred to as VTR), and more particularly to a method for automatically finding tracking optimality using video and audio envelopes. .

In general, conventional VTRs play back tapes recorded on other VTRs or recorders, causing the video head and Hi-Fi audio heads to not accurately track tracks due to X-distance differences with other VTRs, resulting in deterioration of image quality and sound quality. Or the picture quality is good, but the sound quality is poor.

Accordingly, an object of the present invention is to detect an audio and video envelope, and to detect a tape speed change, an abrupt change in an envelope, and a control pulse state to automatically adjust tracking to an optimal state without noise. In providing.

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

1 is a block diagram of the present invention, which includes a first detector 10 for detecting video envelope values, a second detector 20 for detecting hi-fi audio envelope values, serial data (SD), and digital tracking control. A microcomputer 30 for outputting the signal TC and the tape speed control signals TS1 and TS2 and controlling the system as a whole; a servo unit 40 for driving the tape by inputting the serial data SD; The serial data SD, the digital tracking control signal TC and the tape speed control signals TS1 and TS2 are input from the terminal 30, and the head switching pulse HDS and the control pulse CTL are input from the servo unit 40. And a digital tracking control unit 50 for inputting and generating tracking change data (TD) to the microcomputer 30.

2 is an operation waveform diagram according to the present invention, (2a) is a head switching pulse (HDS) waveform, (2b) is an audio or video sampling signal waveform, (2c) is a tracking change data (TRK) waveform, (2d) is a head switching pulse waveform of one cycle for the envelope integration section, (2e) is an audio sampling signal waveform, and (2f) is a video sampling signal waveform.

3 is a flowchart of the present invention.

4 is a tracking optimum point discrimination graph according to the present invention, which shows the relationship between the envelope total value and the tracking data.

The present invention will be described in detail based on the above configuration.

In step (a), the microcomputer 30 checks whether the digital tracking control signal TC is generated and if the digital tracking control signal TC is generated, proceeds to step (b) to output initial tracking data in the digital tracking mode. do.

After the initial data output, proceed to step (c) to detect the falling edge of the head switching pulse (HDS) generated from the servo unit 40, and then the first predetermined time (T1 section in Fig. 2; about 0.5ms) After elapsed), the audio envelope is sampled in step (d).

An audio (or video) envelope refers to an audio (or video) signal recorded on a tape, FM-modulated, and then digitally converted for use by a microcomputer. After that, the video envelope is sampled in step (e) after the second firing time (T2 section in FIG. 2; about 0.25 ms). Sampling is repeated for each of the audio and video signals until the number of samplings is thirty times. The reason why the number of sampling times is 30 is to perform sampling in one head switching pulse period, and one sampling period is four frames.

If it is confirmed in step (f) that the number of sampling has been performed 30 times, the process proceeds to step (g) to calculate the superimposed value (integrated) of the sampled audio and video envelopes. The envelope integration section corresponds to the section T1 as shown in FIG. 2D of FIG. 2.

After performing the sum total value calculation, the process proceeds to step (h) to detect the magnitude of the envelope. As the total envelope value, the magnitude of the envelope is determined. If the following equations (1) to (4) do not hold, the envelope is considered to be smooth.

If the envelope is big

ENV _{t + 1} -ENV _t ≥20LSB ... … … … … … … (One)

ENV _{t + 2} -ENV _{t + 1} ? … … … … … (2)

If the envelope is small

ENV _{t + 1} -ENV _t 20LSB... … … … … … … (3)

ENV _{t + 2} -ENV _{t + 1} 20LSB... … … … … … (4)

to be.

However, the LSB is V _DD x1 / 256, and the time variation of the envelope is in the order of ENV _t → ENV _{t + 1} → ENV _{t + 2} .

After detecting the magnitude of the envelope as described above, the falling edge of the head switching pulse HD is detected in step (i).

After detecting the falling edge of the head switching pulse HDS, the process proceeds to step (j) to change the track data in the track data changing section T4 shown in FIG. 2 and to prepare for the next punctuation in preparation for the two periods of the head switching pulse. Keep the rope detection waiting. The tracking data change operation is referred to as a tracking search, and at this time, an envelope total value of 30 points sampled at each tracking value is compared.

After performing step (j), the process proceeds to step (k) to detect the minimum value of the audio envelope, and if the value is smaller than the number multiplied by 0.5, the audio envelope is ignored and only the video envelope is used.

In this case, if the number of sampling times multiplied by 0.5 is too large, it may take up the capacity of the microcomputer internal RAM. Processes (a) to (k) above are tracking control operation processes.

After performing step (k), the process proceeds to step (l) to detect the peak point of the envelope waveform summation as shown in (4a) and (4b) of FIG. At this time, the priority of the audio envelope with the video envelope is to prioritize the audio envelope to perform tracking control.

Referring to (4b) of FIG. 4, the G3 graph showing the SP mode assuming that the search is started at the time when the tracking data value (initial value) is A and each of the envelope total values is detected at the seven point positions. In this case, the envelope total value is detected in the state where the value of the second point is increased from the starting point by a predetermined increase, and the same value is maintained while three more points are detected, and the two points detected thereafter are sequentially decreased.

At this time, the search is terminated at the time point T1 in consideration of a margin before and after among the points at which the same value is maintained. The G4 graph is a case where the SLP mode is illustrated and is applied in the same manner as the G1 graph.

(4a) does not start tracking in the initial state, but has already performed auto tracking once or when the user manually adjusts the tracking value to an arbitrary value and assumes that the tracking data value of the wrong position is B. The search is terminated at the time T2 at which the same envelope value is detected, similarly to the above (4b). The G1 graph is for the SP mode and the G2 graph is for the SLP mode.

After detecting the peak point in step (l), the process proceeds to step (m) to check whether the detected point is an optimal point and outputs optimal tracking data in step (o).

On the other hand, if it is determined that the optimum point is not detected in step (m), the process proceeds to step (n) to check whether the third predetermined time (about 23ms) has elapsed. If the third predetermined time has not elapsed as a result of the inspection, the loop is looped in the above-described step (d) to repeat the above-described operation to detect the optimum point while changing the tracking data change amount to the third predetermined time. If the tracking optimum point is not detected even after the third predetermined time elapses, the process proceeds to step (p) to output tracking initial data.

The above (l)-(p) process is an optimal point detection process.

After outputting the optimal tracking data in step (o) or outputting the track initial data in step (p), the control proceeds to step (g) to detect the control pulse.

At this time, as the track monitoring mode, the tracking monitoring mode causes the digital tracking operation to be executed if control pulses are not detected five or more times during playback.

Therefore, after detecting the control pulse in step (g), it is checked whether pulses are not input five or more times consecutively in step (2). Looping to the step allows the tracking control operation to be executed again. On the other hand, when the continuously input envelope is detected, it is determined whether the audio and video envelope becomes less than the minimum value (constant voltage) in step (s).

If it is determined in step (t) that the audio and video envelopes are larger than A1 or A2, looping to step (b) described above to re-execute the digital tracking operation, and if not, proceed to step (a) and tape After determining the speed, check whether the speed is changed in step (v).

When the speed is not changed as a result of the check, looping is also performed in the above-described step (b). Steps (b)-(v) above are monitoring processes.

If the speed has not been changed in step (v), the operation proceeds to step (w) to check whether the play mode is canceled, and when it is determined that the play mode has been released, the operation is terminated. Looping to repeat the above-described sensing process.

As described above, the video and audio envelopes are used to automatically control the tracking to be performed at the optimal position, thereby maintaining the optimum image quality and sound quality.

Claims (1)

In the manufacturing method of a tracking of a video tape recorder, a tracking for outputting initial tracking data and then sampling and integrating audio and video envelope signals a predetermined number of times during a one-head switching pulse generation period, and detecting the magnitude of the envelope signal to change the tracking data. An optimum point detection process for outputting optimal tracking data by setting an envelope waveform total value peak point as an optimum point after performing the control process and the tracking control process; and detecting a control pulse after detecting the optimum point for a predetermined number of times in succession. Even if not detected or detected, the monitoring process is performed to control the tracking control process again if the playback mode is not released when the tape speed is changed even if the audio / video envelope is above the minimum value or the audio / video envelope is below the minimum value. Optimal location characterized by Tracking automatic control method.

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