KR0139156B1 - High speed reproducing method using dynamic tracking - Google Patents

Abstract

The present invention relates to a high speed reproduction method using dynamic tracking, in which main data of one field of the present invention is recorded on one track and the screen is composed only of this data during high speed reproduction. In the present invention, important data of one field is set as the trick play data and recorded on some tracks of several tracks. During high speed playback, the dynamic tracking head reads or jumps only the track containing the trick play data and configures the screen with the reproduced signal. When the playback device generates a drive signal to control the movement of the dynamic tracking head, the height of the head is minimized from the center position so that the trick playback track is read or jumped. Therefore, the moving range of the head becomes small during the high speed reproduction, and the effective configuration of the track recording pattern and the drive signal of the head enables noiseless reproduction up to the high speed.

Description

High speed playback method using dynamic tracking

1 is a block diagram of a conventional high speed playback apparatus of a D-3 VCR for broadcasting.

2 is a block diagram showing the structure of a conventional drive circuit.

3 is a diagram showing a head driving trajectory and a drive signal waveform in the conventional triple speed reproduction.

4 is a tape diagram showing a track recording pattern of the present invention.

5 is a waveform diagram of a drive signal at triple speed reproduction according to the present invention.

6 is a waveform diagram of a drive signal at 4 times speed reproduction according to the present invention.

7 is a waveform diagram of a drive signal at 5 times speed reproduction according to the present invention.

8 is a waveform diagram of a drive signal at 7 times speed reproduction according to the present invention.

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

4: central processing unit 5: drive counter

7: mixer 9: drive circuit

17: automatic tracking head 18: strain gauge

The present invention relates to high-speed, high-speed playback without noise of a digital VCR. In particular, the main data of one field is recorded on one track and the screen is composed of only this data during high-speed playback, so that noise-free playback is possible even with a small dynamic tracking head. The present invention relates to a high speed reproduction method using dynamic tracking.

In general, dynamic tracking (Dynamic Tracking) was developed for special playback without noise, and uses a dynamic tracking head in which a piezoelectric element is installed to move the image head up and down. Since the piezoelectric element moves in the vertical direction according to the applied voltage, the position of the image head may be moved according to the voltage. In special playback where the head traces across several tracks, such as high-speed playback, noise occurs when Azimuth passes through other tracks. However, if the head is moved during the special playback using the dynamic tracking head, one track can be completely traced, thereby making noiseless special playback possible.

1 is a block diagram of a conventional high speed reproduction device of a broadcast D-3 VCR developed by Matsushita. As shown, a conventional DTF (Dynamic Track Following) system uses a capstan speed signal (CAPFG) to detect the direction of travel of the tape, and a multiplier that multiplies the frequency of the capstan speed signal (CAP FG). (2) is provided. The FG counter (3) connected to the multiplier (2) and the output of the direction detecting unit (1) receives the respective output signal and the control signal (CTL) to detect the capstan speed, and the detection signal is applied to the central processing unit (4). do. In addition, the central processing unit 4 also receives a reproduction envelope signal EVLP and a control signal CTL. The central processing unit 4 interfaces with the system control unit and outputs control signals for moving the tape and head using the input signals.

The drive counter 5 connected to the output terminal of the central processing unit 4 receives the clock signal CLK and the output signal of the multiplier 2 and generates a drive signal to which the head should move. The output signal of the drive counter 5 is applied to the digital / analog converter 6, converted into an analog signal, and then applied to the mixer 7. In addition, the mixer 7 has an output signal of the delayer 8 delaying the capstan speed signal CAP FG for a predetermined time, an envelope difference signal DIF ENV and an azimuth time signal AZM output from the central processing unit 4. TM) etc. are input and mixed. The drive signal output from the mixer 7 is applied to the drive circuit 9, and the drive circuit 9 moves the head according to the drive signal and checks the movement of the head so that the head actually moves in the same manner as the drive signal. Control.

2 is a block diagram showing the configuration of the drive circuit. As shown, the drive signal supplied from the mixer is applied to the low pass filter 10 so that low frequency components are passed and high frequency components are blocked. The output signal of the low pass filter 10 is applied to the subtractor 11, and the subtractor 11 subtracts and outputs the output signal of the strain gauge 18 from this signal. The output signal of the subtractor 11 is applied to the proportional integration filter 12, and the proportional integration filter 12 filters the output signal to be proportional to the linear combination of the input signal and the temporal integration of the input.

The adder 13 connected to the output terminal of the proportional integral filter 12 adds this output signal and the feedback signal from the TWT amplifier 15 to output to the amplifier 14, and the amplifier 14 amplifies the input signal. Output to TWT (Traveling Wave Tube) amplifier 15. The TWT amplifier 15 amplifies and outputs an input signal in a wide frequency band, and the drive unit 16 connected to the output terminal of the TWT amplifier 15 moves the auto tracking head 17 according to the input drive signal. The strain gauge 18 connected between the automatic tracking head 17 and the subtractor 11 checks the movement of the head and outputs an error signal so that the head actually moves in the same way as the drive signal.

The conventional high speed playback apparatus configured as described above performs noiseless playback up to 3 times speed using an automatic tracking head, and the operation of the conventional high speed playback apparatus will be described based on the 3 times playback example shown in FIG. Same as

3 is a diagram showing a head driving trajectory and a drive signal waveform in the conventional 3x speed reproduction. The dotted line indicates when the dynamic tracking is not performed, and the solid line indicates when the dynamic tracking is performed. In order to reproduce the trajectory indicated by ① in FIG. 3 without noise, the height must be raised by 2 tracks while the head A progresses from the start to the end of the 2 tracks. The trajectory of (2) can be played back without noise when the head B is also raised by 2 tracks in advance and reaches the tape and continues to the end of the track as it is raised by 2 tracks in width. The head trajectory of ③ is traced after the A head, i.e., the + azimuth head, returns to the tape after the head trajectory of ①. The trajectory of this ③ must return 2 track width from the position where the head A exits the track and go back 2 track width while reading the signal to the end of the track. After reading data for one field (three tracks) in this manner, the tracks for two fields are jumped and started again.

However, this conventional method requires the head to move a lot since the data of several tracks for one field must be read and jumped during double speed playback. In other words, assuming that m tracks carry one field of data, a displacement of m (n-1) tw (track width) is required for reproduction without noise at n-times speed. In reality, however, the head cannot have many displacements, i.e., since the movement is limited to a certain degree, noise-free reproduction is possible only at about 3 times normal speed. Therefore, in the case of high speed playback of 3x or more speed, the moving range of the head becomes too large, resulting in a lot of noise, and a lot of noise appears on the playback screen.

SUMMARY OF THE INVENTION The present invention has been made to solve the conventional problems as described above, and an object of the present invention is to record the main data of one field in one track and to configure the screen using only this data during double speed playback, so that the moving range of the head during high speed playback is small. It is to provide a high speed playback method using the dynamic tracking to prevent the excessive force.

Another object of the present invention is to provide a high speed reproduction method using dynamic tracking, which effectively configures a track recording pattern of a tape and a drive signal of a dynamic tracking head to enable noise-free reproduction even when playing at high speed.

The high speed playback method using the dynamic tracking according to the present invention for achieving the above objects comprises the step of setting important data of one field as a trick playback data to record on some tracks of several tracks, and a dynamic tracking head during high speed playback. Comprising a step of configuring the screen with the reproduced signal by reading or jumping only the track containing the trick play data. At this time, when generating a drive signal that controls the movement of the dynamic tracking head, the height of the head is minimized from the center position so that the trick play track is read or jumped.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the attached FIGS. 4 to 8.

The hardware DTF system of the present invention has the same configuration as the high speed playback apparatus of the conventional broadcast D-3 VCR shown in FIG. The head drive circuit of the present invention also has the same configuration as the conventional drive circuit shown in FIG. However, the present invention differs from the prior art in the drive signal generated in FIG. 1 and input into the second road because the track recording pattern of the tape devised in the present invention is different from the prior art.

4 shows a track recording pattern of a tape to which the present invention is applied. As shown in the figure, important data of one field is recorded in the hatched trick play track, and only data in the low frequency region close to the DC component after data compression is recorded in this hatched track. In the remaining two tracks constituting one field, data of a high frequency region is recorded. In normal playback, data of all tracks including the trick play track can be read by the heads A and B alternately to form a normal screen. However, in high speed playback, only the trick play track is read to form the screen. In this way, only a trick play track can be read using a DTF system even at a higher speed than the conventional one, so that the picture quality is somewhat deteriorated, but the screen is not damaged.

FIG. 5 shows drive signal waveforms during triple speed reproduction according to the present invention, in the case of reproducing a tape having the same track pattern as in FIG. Conventionally, in order to play 3 times speed, the head displacement should be gradually increased so that the head is raised by 2 track widths (2tw) while the head A plays track 1, and the displacement must be gradually increased in the same manner in the present invention. In the present invention, track No. 1, which is a track playback track, is read in the same manner. At this time, head B reaches the entrance of track 4 because it is playing at 3 times speed. According to the prior art, the head B must rise in height by a total of 4 tw in order to read the second track to the end. However, according to the present invention, since the head B only needs to read track 4, which is a track playing track, the height needs to be increased by 2tw to read track 4 to the end. When the head A comes back to the tape, the prior art requires that the driver return to the position 2tw higher from the position at the time of exiting the track and climb 2tw again while reading track 3 times. However, according to the present invention, the height of the head A is lowered by 2tw, reaching the entrance of track 7, and then the height is increased by 2tw until the end of the trick playing track. As a result, it can be seen that the required maximum displacement of the A and B heads in the present invention is 2tw, which is reduced compared to the prior art.

FIG. 6 shows drive signal waveforms when the tape having the same track pattern as that of FIG. Conventionally, in order to perform 4x speed playback, the head displacement is gradually increased so that the height of the head A goes up by 3 tw when the track 1 is read to the end, and the track 1, which is a trick playback track, is read in the same manner in the present invention. At this time, the head B reaches the entrance of the track 5 because it is played at 4 times speed. According to the prior art, the height of the head B must rise by a total of 6 tw because the head B must rise 3 tw to reach the entrance of track 2 and then rise further by 3 tw until the end of track 2. However, according to the present invention, since the head B is raised by 1 tw and reaches the entrance of track 4, the head B needs to be increased by 3 tw until the end of track 4, so that the height of the head B may be increased by 4 tw in total.

When head A comes back to the tape, according to the prior art, the head A reaches the entrance of track 5, so the head A rises by 2 tw, reaches the entrance of track 3, and then climbs another 3 tw until the end of the track. When reading track 1, the head height is increased by 3 tw, so the total height of the head A is increased by 8 tw. In the present invention, the head A reads track number seven, but in this case, three field data is displayed while one field data should be displayed, which is the same as three times the speed. Therefore, in order to obtain the effect of 4x speed, track 13 is read by jumping one field. As a result, it can be seen that the required maximum displacement of the A and B heads in the present invention is 4 tw, which is reduced compared to 8 tw of the prior art.

FIG. 7 shows drive signal waveforms when a tape having the same track pattern as in FIG. 4 is reproduced at 5 times speed. In the present invention, the 5x speed reproduction gradually increases the head displacement so that the height of the head A is increased by 4 tw until the end of track 1. Head B is playing at 5x speed, so it reaches the entrance of track 6, but to get the effect of 5x speed, head B jumps up to the entrance of track 10 to reach the entrance of track 10 and then reads the height of head B until the track 10 is completely read. Incrementally by 4tw. Even if head A comes back to tape, the height of head A is gradually increased by 4tw until the track 13 is completely read after the field 1 is jumped to reach the entrance of track 13 to achieve 5x speed. As a result, the required maximum displacement of the A and B heads is 4tw.

FIG. 8 shows drive signal waveforms when a tape having the same track pattern as in FIG. 4 is reproduced at 7x speed. In the present invention, the 7x speed reproduction gradually increases the displacement of the head so that the height of the head A goes up 6 tw until the end of track 1. At this time, head B is 7 times faster, so it reaches the entrance of track 8, and the height of head B is lowered by 2tw, reaching the entrance of track 10, and then the height of head B until the trick playing track is completely read. Is increased by 6tw. When head A comes back to the tape, the track head is jumped to reach the entrance of track 19 to achieve the 7x speed, and then the head height is gradually increased by 6 tw until the trick play track is completely read. As a result, the required maximum displacement of the A and B heads is 6tw.

By applying the same principle as in the above-described embodiment, it is possible to implement by changing the drive signal of the dynamic tracking head appropriately even if the trick playback data is recorded on one track or two tracks without recording on one track. At this time, recording a small amount of trick-play data can increase noise-free double speed, but image quality deteriorates during double speed playback. On the contrary, recording a large amount of trick-play data improves image quality, but has a disadvantage in that the speed is not high.

As described above, according to the present invention, since the main data of one field is recorded in one track and the screen is composed of only this data during double speed playback, the moving range of the head is reduced during high speed playback. In addition, by effectively configuring the track recording pattern of the tape and the drive signal of the dynamic tracking head, there is an effect of enabling noise-free reproduction up to 7 times speed with the dynamic tracking head which was conventionally only 3 times speed playback.

Claims (8)

In a digital recording and reproducing method of recording data of one field into several tracks and playing back by using a dynamic tracking head, Setting important data of one field as trick play data and recording it on tracks of some of several tracks; And a dynamic tracking head configured to read or jump only a track containing trick play data during high speed playback. 2. The high speed reproduction method using dynamic tracking according to claim 1, wherein in the recording step, data of a low frequency region is recorded on a trick play track after data compression, and data of a high frequency region is recorded on the remaining tracks of one field. . 3. The high speed reproduction method using dynamic tracking according to claim 2, wherein the trick reproduction data of one field is recorded in one track. The method of claim 1, wherein in the reproducing step, the driving signal is generated to control the movement of the dynamic tracking head to read or jump the trick replay track while the height of the head is minimized from the center position. High speed playback method. 5. The high speed reproduction method using dynamic tracking according to claim 4, wherein the maximum displacement of the dynamic tracking head is two track widths during the triple speed reproduction. 5. The high speed reproduction method using dynamic tracking according to claim 4, wherein the maximum displacement of the dynamic tracking head is 4 track widths at 4 times speed reproduction. 5. The high speed reproduction method using dynamic tracking according to claim 4, wherein the maximum displacement of the dynamic tracking head is 4 tracks wide at 5 times speed reproduction. 5. The high speed reproduction method using dynamic tracking according to claim 4, wherein the maximum displacement of the dynamic tracking head is 6 tracks wide at 7 times speed reproduction.