JPH058635B2 - - Google Patents

Description

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

Conventional configurations and their problems Traditionally, tape formats that do not satisfy horizontal synchronization and conditions, such as VHS PAL and SECAM,
In the long-time format (8-hour recording mode), the video signal during field still and slow playback has skew distortion and the color order is disordered, making it impossible to convert it into a regular PAL signal or SECAM signal. This is the current situation.

OBJECTS OF THE INVENTION The present invention provides a magnetic recording and reproducing device that can obtain regular signals without skew distortion and color permutation during field still and slow playback even with tape formats that do not satisfy horizontal synchronization alignment conditions. The purpose is to

Structure of the Invention During normal recording and reproducing, the magnetic recording and reproducing apparatus of the present invention arranges R azimuth and L azimuth heads at 180° positions on a rotating cylinder, performs azimuth recording and reproducing of PAL signals or SECAM signals, and performs recording. When performing special playback under the condition that the phase shift between the pattern and the adjacent track is 0.75H, the lead angle is 2N + 1 + 0.25H (N = 0, 1 ，
2, 3…) or the delay angle is 2N-1-0.25H (N
= 1, 2, 3...), demodulates the luminance signal and demodulates the chromaticity signal from the signals reproduced by these two heads, and converts the chromaticity signal or this chromaticity signal into 1H.
A first switch selects one of the delayed signals and adds it to the luminance signal, and a second switch selects and outputs either this added signal or a signal obtained by delaying this added signal by 0.5H. At the same time, the second switch detects the presence or absence of a skew signal indicating a discontinuous point in the horizontal synchronizing signal in the added signal and executes switching, and the first switch detects the discontinuous point in the phase of the horizontal synchronizing signal. The present invention is characterized in that the switching is performed based on a signal synchronized with 1/2 cycle of the skew correction signal generated.

DESCRIPTION OF EMBODIMENTS Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIGS. 1a and 1b are diagrams showing examples of head specifications for field still and slow playback, respectively. Arrow A represents the direction of cylinder rotation.
R ₁ and L ₁ are normal recording and reproducing heads; in the case of a, head L ₂ is arranged close to head R ₁ at an advance angle α; during field still and slow reproduction, heads L ₁ and L ₂ is used. Incidentally, in FIG. 1, R and L of the alpha abbreviation represent the case where the direction of the azimuth inclination is to the right and to the left, respectively. Also, α is the horizontal synchronization signal period of the television system.
It is selected as 1.25H.

FIG. 2 shows the head trajectory during field still playback. In this pattern, the horizontal synchronization misalignment with the adjacent track is 0.25H, and the PAL signal and SECAM
The color arrangement status at the traffic lights is also shown. this is,
This shows a long format pattern in the VHS standard.

FIG. 3 shows the configuration of a circuit for processing a reproduced signal obtained by tracing the trajectory of FIG. 2 by the heads L ₁ and L ₂ of FIG. 1a. Signals from heads L ₁ and L _{2 are amplified via amplifiers 1 and 2} , respectively, a Y signal is demodulated by a luminance signal demodulator 3, and a C signal is demodulated by a chromaticity signal demodulation circuit 4. The C signal output from the chromaticity signal demodulation circuit 4 is output via the 1H delay line 5 or by biasing the 1H delay line 5. The switch 6 is a switch for selecting this, and the output signal of the switch 6 is added to the Y signal output from the luminance signal demodulator 3 at an addition point 16 and output. The switch 8 is a switch for selecting whether the output signal of the summing point 16 is output via the 0.5H delay line 7 or by biasing the 0.5H delay line 7. The 0.5H delay line 7 is for correcting the continuity of the period of the horizontal synchronizing signal during stilling, and performs skew correction. PAL signals and SECAM signals are transmitted using a kind of line sequential method, and B-Y, R-Y, R-
If the permutation of Y is disrupted, color reproduction on the television screen will become unstable. The 1H delay line 5 is for correcting the above color permutation of color signals during still reproduction.

Note that the switches 6 and 8 are switched as follows. The jumbing circuit 10 receives the signal from the addition point 16 via the horizontal separation circuit 9.
The 0.5H skew component is detected and the switch 8 is controlled to perform skew correction. On the other hand, the output signal of the jumping circuit 10 [FIG. 4a] is
1. The chattering component is removed via the waveform shaping circuit 12 and enters the logic circuit 13. This logic circuit 13 inputs the output signal of the waveform shaping circuit 12 [FIG. 4b] and the head switching pulse [FIG. 4c], performs logical processing, and outputs the signal shown in FIG. 4d. The switch 6 is controlled to correct the color permutation.

Note that the signal e in FIG. 4 is a Y/C signal.
Shows the output waveform after MIX. Signal f shows the SYNC waveform after synchronization separation. At this time, the section where the continuity of the H phase is disturbed is indicated by a thick line. In reality, the new phase continues from this thick line section to the next thick line section. (Not only the thick line portion is disturbed.) Signal g shows the waveform of the final output. Signal h indicates the envelope of the head output during field still. The signal i is a waveform obtained by FM demodulating the Y signal from the envelope signal. Signal j demodulates the C signal from the envelope signal (converts the low frequency carrier C signal to the high frequency carrier C signal).
The waveform shown is shown below.

By switching the switches 6 and 8 in this manner, the reproduced video output from the switch 8 becomes a normal signal free from the problem of skewed color permutation.

In FIG. 3, the switch 6 is configured to be switched by the output signal of the logic circuit 13, but since the head _L2 is arranged at an advance angle of 1.25H with respect to the head _R1 , the dashed line in FIG. Waveform shaping circuit 1 as shown
The output of 2 is halved by the flip-flop 14.
Similar results can be obtained by switching using a frequency-divided signal. The circuit configuration can be made even simpler.

In the above embodiment, the head L ₂ was arranged at an advance angle α of 1.25H with respect to the head R ₁ , but this advance angle α is not limited to 1.25H.
(2n+1+0.25)H, however, n=0, 1, 2, 3
It suffices if it is an integer of... Also, head L ₂ is the first
As shown in figure b, the delay angle β is 0.75H for head R ₁ .
It may be placed in Furthermore, this delay angle β is (2n−
1-0.25)H.

In the above embodiment, the head _L1 for normal recording and playback is used for special playback, but this may be configured with four heads by providing two heads for special playback in addition to heads _L1 and _L2 . Just special playback head L ₁ ,
The mounting angle of L ₂ should be set so that it is offset by α and β with respect to the index of 180°.

In the above embodiment, the left azimuth head _L2 was added for special reproduction, but this is done by arranging the right azimuth head _R2 close to the head _L1 at a leading angle α or a lagging angle β. A similar effect can be obtained by performing still and slow playback using a combination of heads _R1 and _R2 .

The main points of the present invention will be explained in detail.

First, the horizontal synchronization phase and color signal permutation during field still will be explained using the field still locus diagram in FIG.

This figure shows a still section corresponding to one field. Field still uses the same azimuth head, so information about adjacent tracks is
It's irrelevant. The 180° allocation angle deviation of heads L ₁ /L ₂ is a lead angle of 1.25H or a lag angle of 0.75H. First, the head specifications corresponding to the conventional plan (first
In the head specifications shown in the figure, if α and β are OH...Actually, they overlap with R, so it becomes +/-2H. ), we will discuss the continuity of the horizontal synchronization signal and the continuity of the color sequence during still playback.

In the phase of the horizontal synchronizing signal at the head switching point in FIG. 2, a discontinuous period of 0.25H occurs in each field. On the other hand, the permutation of color signals is R/
Although the repetition of B/R/B... is maintained, there is a short section of 0.25H, and it can be said that a discontinuous section has occurred.

If you try to restore the continuity of the horizontal synchronization signal in this state, the switching of the delay line for each field will be repeated in the same way from 0H/0.75H/0.5H/0.25H/... and three types of delay lines will be required. Become.

The switching of the 1H delay line for each field of the color signal permutation is 0H/0H/1H/0H/1H/continues.

As described above, it can be seen that in the conventional method, the circuit configuration becomes complicated.

Next, the correction rhythm in the magnetic recording/reproducing apparatus of the present invention will be explained using FIG. 2 as well.

In the case of the magnetic recording/reproducing device of the present invention, the head output phase is OH for the _L1 head and 1.25H for the _L2 head.
Please note that there will be a lead or a delay of 0.75H, and the following explanation is provided.

(1) The phase of the horizontal synchronization signal at the field switching point during still playback is: Head name L ₁ L ₂ L ₁ L ₂ L ₁ Phase difference OH 0.5H 0H 0.5H 0H Head name L ₂ L ₁ L ₂ … The phase difference becomes 0.5H 0H 0.5H...

The permutation of the color signals is: Head name L ₁ L ₂ Permutation 0.25H/0.25H 0H Head name L ₁ L ₂ ... Permutation 0.28H/0.25HX 0HX...

(2) The correction switching rhythm of the delay line in the present invention is as follows:
The result is as follows.

Head name L ₁ L ₂ L ₁ L ₂ L ₁ L ₂ L ₁
L ₂ Skew correction 0.5H 0 00 0.5H 0.5H
0 0 0.5H Color permutation correction 1H 0 0 1H 1H 1H 1H
0H This rhythm is shown in b, c, and d of Figure 4.

In this way, according to the present invention, the types of rhythm and delay lines are simplified, and the hardware configuration can also be simplified.

Next, the waveforms of each part in FIGS. 3 and 4 will be explained a little more.

Signal h shows an envelope waveform picked up by heads L ₁ and L ₂ and amplified by amplifiers 1 and 2 during still operation. The signal i is the Y signal by the demodulator 3.
This shows the waveform when FM demodulated. 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 color permutation is corrected by the 1H delay line and switch 6. The signal e is a waveform obtained by mixing the Y signal and the C signal after color permutation correction. This signal e has
The horizontal synchronizing signal has a discontinuous phase component (0.5H) at the switching point of the head. The situation is H
The output signal f of the separation circuit 9 (indicated by a thick line) also appears as the output signal a of the next jumping circuit (skew detection circuit). The integrating circuit 11 and the waveform shaping circuit 12 are circuits for shaping the waveform of the signal a since a chattering component is found in the signal a. The signal g has a waveform after skew correction is performed by the 0.5H delay line 7 and switch 8.

Signals b, c, and d in Figs. 4 and 5 indicate the ON-OFF status of the 0.5H delay line and 1H delay line, the head L ₁ ,
It shows the correspondence of L ₂ .

Effects of the Invention As explained above, according to the magnetic recording and reproducing apparatus of the present invention, the video output signal during field still and slow playback can be a regular PAL signal or SECAM signal without skew distortion or color permutation disturbance. It is what it is. Furthermore, since two heads are arranged with a lead angle of (2n+1+0.25)H or a delay angle of (2n-1-0.25)H, the configuration of the delay line changeover switch generation circuit is simplified.

[Brief explanation of the drawing]

The drawings show an embodiment of the invention, and FIGS. 1a and b
Figure 2 is a cylinder configuration diagram showing the head specifications.
FIG. 3 is a block diagram of a reproduction signal processing circuit, and FIG. 4 is a waveform diagram of each part during still reproduction in the VHS standard extended format. _L1 , _L2 ...head, 3...luminance signal demodulator, 4...
Chromaticity signal demodulator, 5...1H delay line, 6...Switch (first switch), 7...0.5H delay line, 8...Switch (second switch), 9...Horizontal separation circuit, 1
0... Jumping circuit, 11... Integrating circuit, 12...
Waveform shaping circuit, 13...logic circuit, 14...flip-flop, C...head switching pulse.

Claims (1)

[Claims] 1. During normal recording and reproduction, R is placed on the rotating cylinder.
When the azimuth and L azimuth heads are arranged at 180° positions, the PAL signal or SECAM signal is recorded and reproduced in the azimuth, and the special reproduction is performed under the condition that the phase shift between the recording pattern and the adjacent track is 0.75H, the recording patterns are the same as each other. When two heads with azimuth are indexed at 180°, the lead angle is 2N+1+
Arranged so that the delay angle is 0.25H (N = 0, 1, 2, 3...) or 2N-1 - 0.25H (N = 1, 2, 3...), and playback by these two heads. The luminance signal and chromaticity signal are demodulated from the signal, and either the chromaticity signal or the signal obtained by delaying this chromaticity signal by 1H is output as the first signal.
The second switch is configured to select and output either this added signal or a signal obtained by delaying this added signal by 0.5H. Switching is performed by detecting the presence or absence of a skew signal indicating a discontinuous point in the horizontal synchronizing signal in the added signal, and the first switch detects a discontinuous point in the phase of the horizontal synchronizing signal and outputs a skew correction signal generated. A magnetic recording/reproducing device configured to perform switching based on a signal synchronized with a 1/2 cycle of. 2. The magnetic recording/reproducing apparatus according to claim 1, wherein the first switch is configured to be switched by a logic processing signal of a skew correction signal and a head switching pulse. 3 Turn the first switch to set the skew correction signal to 1/
2. The magnetic recording/reproducing apparatus according to claim 1, wherein the magnetic recording/reproducing apparatus is configured to be switched by a signal via a frequency divider circuit.