JPH058634B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetic recording and reproducing apparatus having a field still function, among helical scan type magnetic recording and reproducing apparatuses.

Conventional configurations and their problems In tape formats that do not satisfy horizontal synchronization conditions, such as VHS PAL and SECAM long-time formats (LP mode), the color permutation of the playback signal during field still and slow playback is difficult. Bad sex. However, the current state of the art is that it is not possible to improve color permutation and obtain stable images with a simple configuration.

Purpose of the Invention The present invention has a simple configuration and provides a tape format that does not satisfy the horizontal synchronization condition, but can improve color permutations and obtain stable images during field still and slow playback. The purpose is to

Structure of the Invention During normal recording and reproduction, the magnetic recording and reproducing apparatus of the present invention has R azimuth and L azimuth heads arranged at 180° positions on a rotating cylinder, performs azimuth recording and reproduction of PAL signals or SECAM signals, and records. When performing special playback under the condition that the pattern arrangement is 0.75H (phase shift αH with the adjacent track as shown in Figure 2), two tracks with the same azimuth
The angle of shift for each head is 180°.
The brightness signal and chromaticity signal are demodulated from the signals reproduced by these two heads, and either the chromaticity signal or the signal delayed by 1H of this chromaticity signal is selected using a switch. The color signal is added to the luminance signal and outputted, and the switch is controlled by a signal related to a head switching pulse to improve the permutability of the color signal of the reproduced signal.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below based on the drawings. Figure 1 shows head specifications for field still and slow playback. Heads A and B are for normal recording and playback, and C is a special playback head.Head A has R azimuth, B and C have L azimuth, and during still and slow playback, heads B and C are used.
used. Here, arrow I indicates the cylinder rotation direction, and head C is arranged at an advance angle β with respect to head A. For example, β=2H.

FIG. 2 shows the head trajectory during field still playback. The recording pattern is such that tracks R ₁ , L ₁ ,
It is recorded as R ₂ , L ₂ .... In Fig. 2, only the _L2 track is played back when playing stills. Horizontal synchronization with adjacent tracks is
It is off by 0.25H. Therefore, during field still playback, the continuity of the horizontal synchronizing signal will deviate by 0.25H for each field. In addition, PAL
In the signal or SECAM signal, the color signal is sent in a kind of line-sequential manner, and here the color signal (B-
The arrays Y) and (RY) are represented as R and B. The permutation of this color signal is important during still playback.
At the discontinuous part of 0.25H, the B-Y signal section is 0.25H.
This results in an imbalance, and the color killer of color television receivers becomes unstable, resulting in color flickering and black-and-white phenomena.

More specifically, the horizontal synchronization phase and color signal permutation during field still will be explained using the field still locus diagram in FIG. 2. FIG. 2 shows a still section corresponding to one field. Since field still uses the same azimuth head, information on adjacent tracks is irrelevant. The 180° allocation angle deviation of heads B/C shall be 0H or 2H.

The phase shift of the horizontal synchronizing signal at the field switching point during still playback is as follows: Head Name B C B C... Phase Difference 0.25H 0.25H 0.25H 0.25H... In other words, it represents the phase difference between the start and end of the field.

The indexing angle of the head may be 0H or 2H, because in the case of PAL and SECAM signals, the permutation of color signals is repeated at 2H.

Similarly, the permutation of color signals is Head name B C Color signal irregular section 0.25H(B) 0.25H(B) Head name B C… Color signal irregular section 0.25H(B) 0.25H(B)… becomes.

In other words, it represents the color signal irregular section at the starting end of the field. This is the color signal permutation (R/
B/R/B...) is normal, but 0.25H
This section occurs in the B signal. for this section
TV receivers will malfunction when demodulating color signals. In other words, the regular 1H is 0.25H, which is too short for TV.
This is because the circuit of the receiver cannot operate normally.

The situation is as follows.

In the case of Figure 3, the head shift angle is 0H. As shown in Figure 3, instead of head C, head D,
The same is true even if E is provided and still playback is performed.

This problem is improved in the present invention as follows. In the present invention, during field still playback, it is assumed that there is a slight curvature at the top of the screen due to a deviation in the continuity of the horizontal synchronization signal (0.25H), but this is tolerable. This is corrected by switching the 1H delay line. Almost the same idea applies to throws.

FIG. 4 shows the main structure of a magnetic recording/reproducing apparatus according to the present invention. This figure also includes a circuit for correcting the fact that the H continuity shifts by 0.5H and the color permutation shifts by 1H during CUE/REVIEW playback.

In the case of the cylinder configuration shown in Fig. 1, the reproduced signals from heads B and C are amplified by amplifiers 1 and 2, respectively, the Y signal is demodulated by the luminance signal demodulator 3, and the C signal is demodulated by the chromaticity signal demodulation circuit 4. is demodulated.
The C signal output from the chromaticity signal demodulation circuit 4 is output via the 1H delay line 5 or by bypassing the 1H delay line 5. Switch 6 is the switch that selects this, and the output signal of switch 6 is the addition point 19.
It is added to the Y signal output from the luminance signal demodulator 3 and output. The output signal of the summing point 19 is output via the 0.5H delay line 7 or by bypassing the 0.5H delay line 7. Switch 8 is the switch that is selected.

First, I will briefly explain CUE/REVIEW time.

During CUE/REVIEW, the head scans over adjacent tracks, so the continuity of H shifts by 0.5H at the track switching point. To correct this, the 0.5H delay line 7 is switched by a switch 8. The switch 8 is controlled by a jumping circuit 10 via a horizontal synchronizing signal separation circuit 9, which catches disturbances in the phase continuity of the horizontal synchronizing signal. On the other hand, 1H to correct the continuity of color signal
Control of the switch 6 for switching the delay line 5 is performed by passing the output of the jumping circuit 10 through an integrating circuit 11 and a waveform shaping circuit 12, and then dividing the frequency into 1/2 by a flip-flop 15 and passing it through a switch 17. The phase inverter 13 is CUE/
Switch 14 is used to switch during REVIEW. That is, a selection is made as to whether the 1/2 frequency division operation is performed on a rising pulse or on a falling pulse.

FIG. 5 shows waveforms of various parts during CUE/REVIEW.
Waveforms C and C' indicate the time of CUE and the time of REVIEW, respectively.

Next, the still mode will be explained. Since the 0.25H delay operation is not performed during still playback, the switch 8 is set to the through side. It is controlled by a control signal of logic circuit 18 via switch 16. Also, in order to correct the color permutation, the head switching pulse d is applied to the logic circuit 18, switch 1
7 to the switch 6. Figure 6 shows this situation. To explain the state of the color permutation using the above-mentioned Fig. 2, the 1H delay line 5 turns ON and OFF in accordance with the head switching period, which means that the color permutation at this switching point is in a 0.25H interval. This shows that the period is 1.25H.

Head name B C Color signal irregular section 1.25H(B) 1.25H(R) Head name B C... Color signal irregular section 1.25H(B) 1.25H(R)... This is for the regular period 1H. The extremely short period of 0.25H changes to 1.25H, which is a little longer, so the TV receiver circuit can operate normally.

By doing so, the color permutation of the reproduced signal is improved, and the killer operation of the television receiver can be stabilized.

Next, the operation of the fine throw will be explained.

Fine throw is a method in which the tape is intermittently fed each time a fine throw command pulse (FIG. 7-e) is received, and the tape is moved to the next video track for slow playback. When it comes to field throw, when moving to the next track, only the same azimuth track can be picked up, so information on adjacent tracks is ignored, and the relationship with adjacent adjacent tracks becomes important. At this time, the H alignment with the adjacent adjacent track is 0.5H off. In other words, at the moment the tape moves, it moves to the adjacent track, so the continuity of H is shifted by 0.5H, so switching the 0.5H delay line 7 is done by using the head switch in the same way as during still playback. This is done in conjunction with a pulse d.

However, regarding the switching part of 0.5 delay line 7,
Some things will change. FIG. 7 shows this situation. The fine slow start signal e generates a pulse each time the tape is moved one frame at a time. 8th
Waveform f in the figure shows how the tape moves in accordance with the pulses of waveform e. The logic circuit 18 performs logical processing according to the head switching pulse d, the fine slow start signal e, the still command 20, and the fine slow command 21,
As mentioned above, a control signal for switching between the 0.5H delay line 7 and the 1H delay line 5 is created.

Next, FIG. 4, FIG. 6, and FIG. 7 will be explained a little more. Signal h is still picked up by heads B and C, and amplifiers 1 and 2 when slow.
shows the envelope waveform amplified by . signal i
shows the waveform when the Y signal is FM demodulated by the demodulator 3. Signal j shows a waveform obtained by converting the C signal from a low band carrier color signal to a high band carrier color signal by the demodulator 4 (this operation is based on the VHS format). The delay line and switch 6 correct the color permutation. The signal k is a waveform obtained by mixing the Y signal and the C signal after color permutation correction. This signal g is connected to 0.5H delay line 7 and switch 8.
This is the waveform after 0.5H skew correction was performed. However, regarding skew distortion of 0.25H,
Ignoring it.

Effects of the Invention As explained above, the magnetic recording/reproducing apparatus of the present invention has a simple configuration in which the 1H delay line is turned on and off by a signal related to a head switching pulse, and can be used in a format without horizontal synchronization. For example, VHS standard PAL signal, SECAM
It can improve color permutation in long signal formats (αH is 0.75H), and can reproduce stable color images in field still and slow motion.

The key point of the present invention is to limit the color permutation to field stills and to change the color permutation irregular interval from 0.25H to 1.25H.
(The regular interval is 1H.)
This simplifies the color permutation correction circuit (simply uses head switching) and enables special reproduction.

[Brief explanation of the drawing]

Figs. 1 and 3 are respectively explanatory diagrams of the head installation state of the field still regeneration cylinder, Fig. 2 is an explanatory diagram of the head trajectory on the pattern during field still, and Fig. 4 is a main part of an embodiment of the present invention. Diagram,
Figure 5 is a waveform diagram of each part during CUE/REVIEW in Figure 4, Figure 6 is a waveform diagram of each part during field still in Figure 4, and Figure 7 is a waveform diagram of each part during field still throw in Figure 4. Figure, 8th
The figure is an explanatory diagram of the movement state of the tape during slowing. 3...Y signal demodulator, 5...1H delay line, 6...switch, 7...0.5H delay line, 8...switch, 9...horizontal synchronization signal separation circuit, 10...jumping circuit,
18...Logic circuit, 19...Summing point, B, C...Head, d...Head switching pulse.

Claims (1)

[Claims] 1. During normal recording and reproduction, the R azimuth and L azimuth heads are arranged on a rotating cylinder at 180° positions, and the PAL signal or SECAM signal is azimuthally recorded and reproduced so that the arrangement of the recording patterns is 0.75. H
When performing special playback under the condition of (phase shift αH with adjacent track), two heads with the same azimuth are arranged so that the offset angle is 0H or 2H with respect to the index of 180°. Then, the luminance signal and chromaticity signal are demodulated from the signals reproduced by these two heads, and the chromaticity signal or this chromaticity signal is converted to 1H.
A switch is configured to select one of the delayed signals, add it to the luminance signal, and output the resultant signal.
A magnetic recording/reproducing device configured to control the switch with a signal related to a head switching pulse. 2 Switch the switch in accordance with the head switching pulse period to change the color order at this switching point.
2. The magnetic recording and reproducing apparatus according to claim 1, wherein a 0.25H section is changed to a 1.25H section.