JPS6151830B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a video signal recording/playback device that enables long-time recording, compactness and weight reduction, and is capable of performing special playback such as still playback, slow-motion playback, high-speed playback, and reverse playback. This also provides a means for obtaining continuity of the horizontal synchronizing signal as in normal reproduction.

In recent years, there has been a trend toward higher density, smaller size, and lighter weight for home VTRs, and the two-head helical scan system has become more popular.
In VTRs, a recording system in which two heads are provided with azimuth angles and no guard band is provided between adjacent tracks has become common. By setting an azimuth angle between the two heads, even if one head travels on a trajectory recorded at the opposite azimuth, the signal will hardly be regenerated due to azimuth loss, eliminating the guard band. making it possible.

In this type of helical scan VTR, signals between adjacent tracks are difficult to maintain due to interference of adjacent signals and continuity of signals during special playback (generally referred to as static playback, slow-motion playback, high-speed playback, and reverse playback). The order of is important. Figure 1 shows the recording trajectory of a general 2-head helical scan VTR.
The relationship between the line deviation amount a between adjacent tracks and the specifications will be explained. In Figure 1, a rectangular parallelepiped
A ₁ B ₁ C ₁ D ₁ , A ₂ B ₂ C ₂ D ₂ , A ₃ B ₃ C ₃ D ₃ ... are the recording trajectories on the tape, and A ₂ B ₁ C ₂ D ₁ is the head when the tape is stationary. _WV : Effective recording width of video signal on the tape corresponding to 180° rotation of the head V _T : Tape speed _fV : Frequency of track switching (one track per track)
R: Head rotation radius ' _H : Recording length of one line on a stationary pattern _nH : Number of signal lines formed in one track (180° rotation of the head) (one track is the field frequency) 1
In the field, it is the number of lines in one field) _aH : Amount of line deviation from the adjacent track. As shown in the figure, A ₂ B ₁ is 180 of one head.
゜The length of rotation, A ₁ A ₂ is 1 track (1 head)
A ₂ O is the length of the signal deviation from the adjacent track on the stationary pattern, OB ₁ is the length of the n _H line on the stationary pattern, B ₁ T Since is the video recording width, _{2 1} =πR . . _{. 1 2} =V _T /f _V . . _{. 2 = H ′ ・ a H .} ,, From the formula, _H ′・(n _H +a _H )=πR...Furthermore, since ΔA ₂ B ₁ T is a right triangle, Since ΔA ₂ B ₁ T and ΔA ₂ A ₁ O are similar, Therefore, Substituting _H ′ in equation (6) into equation (8), Equation (9) expresses the relationship between the signal deviation amount a _H between adjacent tracks and the specifications. Although FIG. 1 shows the head rotation direction and the tape running direction as being the same, in the opposite case, a _H may be considered negative.

Next, the importance of the line deviation amount a _H between adjacent tracks will be described. FIG. 2 shows the recording trajectory of a helical scan VTR and the head trajectory for special playback (the figure shows high-speed playback). In Figure 2, -A, -B, -A, -B,...
is the recording trajectory, the shaded area is the head trajectory during special playback (high-speed playback), and T _P is the track pitch. As can be seen from the figure, during special playback, one head plays back over a plurality of recording trajectories. In the figure, one head has -A, -B, -
The track is played sequentially to tracks A, -B, -A, and then -A, -B, -A,
- Track B... is played sequentially (no azimuth).

At this time, if the record has a guard band, the guard band passes during each track transition. In such cases, discontinuities in the playback signal may occur when tracks change during playback on one head and when switching heads. In other words, if the horizontal synchronization signals between adjacent tracks are not lined up, the time interval of the horizontal synchronization signals when switching tracks will be different from when playing one track, causing discontinuity in the horizontal synchronization signals, which will cause problems on the TV screen. This appears as skew distortion. Also, in Fig. 2, when switching heads, -
From the end of A track to the beginning of A track. At this time, xT _P of the track pitch T _P
Assuming that the switch is made at a position advanced by (O≦x≦1), as can be seen from the figure, the previous head will play back the (1-x) _aH line more than the normal end of the -A track, and the second At the start of the head of the track - play back xa _H lines more than the normal start of the A track. And since it returns from the end of the -A line to the start, the signal returns to the previous signal by a total of n _H + (1-x) a _H + xa _H = n _H + a _H lines. Therefore, n _H +
If a _H is an integer, the horizontal synchronizing signal will be continuous during such head switching, but if n _H +a _H is not an integer, the horizontal synchronizing signal will not be continuous. The above-mentioned condition that adjacent horizontal synchronization signals are lined up is that the line difference with the signal of the next or previous track is n _H + a _H , so n _H + a _H can be said to be an integer, and the head Matches the conditions at the time of switching. Second
In the figure, high-speed playback has been explained as an example, but the state of head switching and track shifting is exactly the same during stationary playback, slow motion playback, and reverse playback. However, in these cases, during playback with one head, the head shifts to the previous track. Therefore, in a recording system that does not provide an azimuth angle, the condition for continuity of the horizontal synchronizing signal during special playback is n _H +a _H =m (m: integer)... In the system of recording one field on one track, n _H =(2k+1)/2 (k: integer), so equation (10) becomes a _H = (2+1)/2 (: integer)...'.

The above has described the continuity of horizontal synchronization signals, but for VTRs that record PAL and SECAM color television signals (hereinafter referred to as PAL signals and SECAM signals), the arrangement of color signals is also important. In the PAL signal, the position of the color carrier wave of the RY signal is reversed for each line, and in the SECAM signal, the RY signal and BY signal are transmitted alternately as frequency modulated waves for each line. ing. In either case, the receiving side determines the order of the color signals and
It is demodulated to the regular color signal. Therefore, if the order of the color signals changes in the middle or beginning of a field, the television receiver's color discrimination circuit may malfunction, or it may take a long time for the color signal to be read in, resulting in the color not being displayed or the screen being distorted. The hue may be distorted in the middle or at the top. Therefore, it is important that the order of the color signals in the VTR output signal is not reversed even during special playback. In the recording pattern shown in Fig. 2, the condition for satisfying this is that the line increase/decrease n _H +a _H when the head moves to the adjacent track and when switching heads is an even number, that is, n _H +a _H =2m (m: integer)... For PAL and SECAM signals, the number of lines in one field is 312.5, so in the system of recording one field on one track, formula (11) is a _H = 2m - 312.5 = 4 + 3/2 (: integer)...' Become. In a recording method in which the head rotation direction and tape running direction are the same (a _H > O), |a _H | = 1.5, 3.5, 5.5... In a recording method in which the head rotation direction and tape running direction are opposite (a _H < O), , |a _H |=0.5, 2.5, 4.5...

Taking into consideration the points explained above, for conventional VTRs capable of special playback, a _H that also satisfies the formula, especially for PAL and SECAM type VTRs, is selected, and the specifications can be determined from the formula. Furthermore, in a VTR without a guard band, although an azimuth angle is provided between the heads, it is difficult to avoid being affected by adjacent interference signals to some extent. Since the luminance signal is normally recorded as a frequency modulated wave, the further the frequency of the interference signal is from the frequency of the main signal, the higher the level of the interference signal after demodulation becomes. The same can be said of the SECAM carrier color signal since it is a frequency modulated wave. Therefore, if the adjacent interference signal has almost the same information as the existing signal, the amount of interference will be very small. NTSC,
Since the PAL carrier color signal transmits information using the phase and amplitude of the carrier wave, adjacent interference can be removed using the line correlation of the phase of the carrier wave.
The more similar the information between the adjacent interference signal and the main signal, the less interference there will be. From the above points, in a recording system that does not provide a guard band, it is preferable to satisfy the equations (PAL, SECAM) in order to enable special playback, and even when special playback is not performed.

Taking these points into consideration, a home VTR was basically designed with a _H = 1.5, using a 1/2-inch wide tape, setting azimuth angles on two heads, and recording one field per track. It is commercially available. Figure 3 shows an example of such a VTR.
This shows the recording pattern of a VTR for VHS format PAL or SECAM signals. In Figure 3, I-A, -
B, -A,... represent the recording tracks as in Fig. 2, -A, -A, -A,... are the trajectories written by the A head, -B, -B, -B...
is a locus drawn by the B head, and an azimuth angle of ±6° is provided between the A head and the B head (not shown in the figure). Also, -1, -2, -
3, . . . represent line numbers, and the appended R and B represent the color signals of the lines. That is,
In the PAL signal, the phase of the RY signal is inverted for each line, and the positive state of the RY signal is represented by R, and the negative state of the RY signal is represented by B. In addition, in the SECAM signal, the R-Y signal and the BY signal are transmitted alternately for each line, but the state in which the RY signal is transmitted is the state in which the R and BY signals are transmitted. is represented by B. In addition, a _H is the amount of deviation of the horizontal synchronization signal between adjacent tracks;
In the SECAM signal VTR, a _H is set to 1.5. In addition, the track pitch T _P at this time is 49μ
m, tape speed is 23.4mm/S.

In this way, for VHS system PAL, SECAM signal
In a VTR, horizontal synchronization signals between adjacent tracks are lined up, and adjacent color signals are also lined up. That is, the neighbor of R is R, and the neighbor of B is B.

However, in recent years, there has been a growing demand for higher density VTRs. The only way to increase the density while keeping the current cylinder diameter (head rotation diameter) and tape width is to slow down the tape speed _VT . At this time, as can be seen from the formula, a _H becomes small. However, when |a _H |<1.5, only a _H =±0.5 satisfies the formula ', and only a _H =-0.5 satisfies the formula '. VHS format PAL,
With SECAM VTR, slow down the tape speed a _H
= 0.5, the tape speed is V _T = 7.8mm/
S, the track pitch becomes T _P =16 μm, and the audio performance and image quality become extremely poor. In addition, apart from the pattern in Figure 3, if you are trying to increase the density by reducing the cylinder diameter (reducing πR in the formula), select a _H that satisfies the formula or formula using other constraints. Sometimes it is not possible.

From this point of view, methods have been proposed to compensate for some or all of the disadvantages mentioned above even for a _H that does not satisfy the equation. One of them is, as described in Japanese Patent Application Laid-open No. 52-105729, the frequency modulation carrier frequency of the luminance signal is (h+1/2) f _H [h: 0 or a positive integer, f _H :horizontal frequency], and in this way, even when there is no correlation between adjacent signal information, interference from adjacent signals can be reduced. However, with this method, it is generally not possible to obtain continuity of color signals in horizontal synchronization signals and PAL and SECAM signals during special playback. VTRs with a _H = 0.75 using this method are also commercially available.

Next, another method will also be explained. This is 2
This is a method of arranging the signals on the recording pattern by shifting the angle between the two heads from 180 degrees. Fig. 4 shows an example of the head arrangement, and Fig. 5 shows the a _H = 1.0±0.5 line.
It is a recording pattern diagram of PAL and SECAM VTR.

As shown in Figure 5, of both heads A and B,
One head is shifted from 180° by an angle θ corresponding to 0.5 line on the recording pattern.
FIG. 4 shows the case where the B head is delayed from the 180° position of the A head by an angle equivalent to 0.5 line. The recording pattern at this time is shown in FIG. In FIG. 5, the symbols are the same as in FIG. In the pattern shown in FIG. 5, since the luminance signals have almost the same information between adjacent tracks, adjacent interference of the luminance signals and continuity of the horizontal synchronizing signal during special playback are solved. However, in terms of color signals, -A, -B, -A and -B, -A and -B... In the tracks, the neighbor of R is R and the neighbor of B is B, but -B and - A,-
B and -A, -B and -A... In the tracks, B is next to R. Therefore, adjacent interference of color signals and continuity of color signals during special reproduction have not been solved. To solve these problems, for example,
-A and -B, -A and -B... There is a method of recording the track color signal delayed by one line.
By doing so, the latter problem can also be solved. In addition, in Figures 4 and 5, the B head is
Although the explanation was given by delaying by an angle equivalent to 0.5 line, if it is advanced, the arrangement of colors will be reversed. In addition, although Fig. 5 shows and explains the patterns for PAL and SECAM signals, in the case of NTSC signals, the color signals include R and B.
There is no distinction between the two, and all can be solved by simply shifting the head by an angle equivalent to 0.5 line.

However, with this method, the two conventional heads
If you want to use a VTR mounted at 180 degrees and switch the speed, the disadvantage is that you will have to use three or four heads.

A basic block diagram of the signal processing of home VTRs currently in use is shown in FIG. 6, and will be briefly explained. In FIG. 6, 1 is a video signal input terminal, 2 is a low-pass filter, 3 is a bandpass filter, 4 is a frequency modulator, 5 is a frequency converter, 6 is an adder,
7 is a video head, 8 is a high-pass filter, 9 is a low-pass filter, 10 is a frequency demodulator, 11 is a frequency converter, 12 is an adder, and 13 is a video signal output terminal. A video signal applied to an input terminal 1 is separated into a luminance signal and a carrier color signal by a low-pass filter 2 and a bandpass filter 3. The luminance signal is converted into a frequency modulated wave by a frequency modulator 4 and guided to an adder 6. On the other hand, the carrier color signal is converted to a lower frequency by a frequency converter 5, superimposed on the frequency modulated wave by an adder 6, and recorded on a tape via a head 7. During frequency conversion to this low range, NTSC,
Signal processing is applied to each PAL and SECAM signal. The signal reproduced from the head 7 is separated by a high pass filter 8 and a low pass filter 9 into a frequency modulated wave of a luminance signal and a carrier color signal converted to a low pass. The frequency modulated wave is guided to a frequency demodulator 10 and demodulated to obtain a reproduced luminance signal, which is then guided to an adder 12. On the other hand, the carrier color signal converted to a low frequency band is returned to its original frequency by a frequency converter 11, and added to the reproduced luminance signal by an adder 12, so that a reproduced video signal is obtained at an output terminal 13. In the process of returning the carrier color signal to its original frequency in the frequency converter 11, signal processing is performed according to each of the NTSC, PAL, and SECAM signals. Further, in the case of a black and white signal, a color signal processing system is not required and a color signal processing system is not added, but the color signal is blocked by a color killer circuit.

As mentioned above, in conventional two-head helical scan VTRs, taking special playback into consideration, either set a _H to a value that satisfies the formula ('), or set it to another value to sacrifice special playback. I've been

The present invention provides continuity of the horizontal synchronizing signal during special playback while keeping the angle between the two heads at 180°, and achieves high density, and an _aH pattern that can be easily switched from the conventional pattern. and provides a VTR having this _aH .

One key point of the invention is that it employs azimuth recording. Special reproduction in the case of azimuth recording is different from that in FIG. 2. The gist of the present invention is to perform special playback on a VTR in which the head for playing back adjacent recording trajectories has an azimuth angle _.
The relationship between the continuity of the horizontal synchronization signal and color signal (for PAL and SECAM signals) is derived, and the effective
The key is to select _H. Below is something like this
This section explains how to perform special playback on a VTR.

FIG. 7 shows the trajectory of the head in static playback, FIG. 8 in high-speed playback, and FIG. 9 in reverse playback, where A◯ is the trajectory of the A head and A is the trajectory of the B head. However, in FIG. 7, both heads A and B draw the same trajectory. As mentioned above, since both the A and B heads are provided with an azimuth angle, the A head receives only the signal of the trajectory written by the A head, and the B head receives only the signal of the trajectory written by the B head. Reproduce. Therefore, in FIGS. 7 to 9, the signals in the shaded areas are reproduced. In FIG. 7, the A head reproduces the signal in the shaded area, and the B head reproduces the signal in the shaded area. During such special playback, the recording trajectory may be jumped during one playback of one head, or the signal order may be different from that in normal playback when switching heads. These states can be categorized as follows: 1. During one playback of one head, a transition occurs to the next recording trajectory (during high-speed playback). [In Figure 8, the transition from the -A trajectory of the A head to the -A trajectory, and the transition from the -B trajectory to the -B trajectory of the B head] 2. Transition to the next recording trajectory when switching heads ( (when playing still, slow, fast, or in reverse).

[In Figure 8, the transition from the -B trajectory of the B head to the -A trajectory of the A head, and in Figure 9, the transition from the -A trajectory of the A head to the -B trajectory] 3. Move to recording trajectory (during high-speed playback).

[In Figure 8, the transition from the -A trajectory of the A head to the -B trajectory of the B head] 4. Transition to the previous trajectory when switching heads (during stationary, slow, and reverse playback).

[In Figure 7, the transition from the -A trajectory of the A head to the -B trajectory of the B head] 5 During one playback of one head, transition to the two previous recording trajectory (during stationary, slow, and reverse playback) ).

[In Figure 9, from the A trajectory of the A head]
There are five ways: transition to A locus, transition from -A locus to -A locus, and transition from -B locus to -B locus of the B head. In the five cases mentioned above, the continuity of the horizontal synchronization signal and the continuity of the color signal in PAL and SECAM signals are important. If the continuity of the horizontal synchronization signal is lost, skew distortion will occur on the screen. If the continuity of the color signal is disrupted in PAL and SECAM signals, the color may not appear or the hue may be distorted.

Next, for the five cases above, we will discuss the continuity of a _H , horizontal synchronization signal, and color signal (PAL, SECAM).
I will explain about it. If it is 1, one head moves to the next track. The signal reproduced at this time shifts to 2n _H +2a _H lines ahead of the normal reproduction. In the case of 2, the signal transitions exactly the same as during normal playback when switching heads, and any a _H
horizontal sync signal and PAL,
The continuity of the color signal in the SECAM signal is maintained. 3
In this case, when switching the head, _{2nH is lower} than during normal playback.
+2a Move to the signal ahead of _{the H} line. For example, the 8th
In the transition from -A to -B in the figure, the signals on the a _H line at the end of the -A track, -B, all of the -A tracks, and the a _H line at the beginning of the -B track are 2n _H +2a _H in total. The line signal is skipped. In the case of 4, when switching heads, the signal shifts to a signal 2n _H + 2a _H lines earlier than during normal playback. For example, in the transition from -A to -B in FIG. 7, the signal shifts from the signal a _H line ahead of the end of the -A track to the signal a _H line before the beginning of the -B track. That is, it moves to all of the -A track and -B track and before the 2a _H line (2n _H + 2a before _{the H} line). In case 5, it is the opposite of case 1, in that during playback of one head the track moves to the previous track, so it moves 2n _H +2a _H lines earlier than during normal playback. The present invention is to find a condition for the horizontal synchronization signal to be continuous at all times, and to set _aH to this value. This condition is that the number of lines skipped or the number of lines reversed 2n _H +2a _H is an integer, 2n _H +2a _H = m (m: integer) n _H +a _H = m/2 (m: integer ) …… becomes. In the system of recording one field on one track, the formula is a _H =/2 (: integer)...'. Furthermore, the condition for the color signals to be continuous in PAL and SECAM signals is that 2n _H +2a _H is an even number, and n _H +a _H =m (m: integer) . . . In the system of recording one field on one track, the formula is a _H = m-312.5 = 2 + 1/2 (: integer)...'.

Taking the above points into consideration, the present invention guarantees sufficient sound quality and image quality for a home VTR, and then performs special playback when increasing the density, or even when the formula cannot be satisfied under various conditions. At times, it is attempted to provide a pattern that provides at least continuity of the horizontal synchronization signal. This is because, as mentioned above, interference caused by differences in luminance signal information between adjacent tracks can be easily reduced by the method described in JP-A-52-105729, and adjacent interference of color signals can be easily reduced. can be removed in NTSC and PAL signals by using the line correlation of the carrier color signal, and since the carrier color signal has a carrier frequency of 3 to 5 MHz and a band of about 1 MHz, it can be easily removed with a 0.5 line to 2 lines of ultrasonic delay line. It can be processed. However, since the luminance signal has a DC bandwidth of 3 to 4 MHz, even if an ultrasonic delay line is used, it must be a modulated wave with a carrier of at least 10 MHz, and a broadband, high-performance delay line must be used. It is complicated and expensive. Therefore, it is very effective to be able to obtain at least the continuity of the horizontal synchronizing signal during special playback. Furthermore, in the case of a black-and-white signal or an NTSC signal, there is no need to consider the continuity of the color signal, so only the continuity of the horizontal synchronization signal is sufficient.

Two heads with azimuthal angles to each other at 180
The condition for obtaining continuity of the horizontal synchronization signal during special playback with a VTR placed opposite to the angle is as follows. At a _H that satisfies this formula, the formula ('formula)
There are also those who are satisfied with. Since it is known to select a _H so as to satisfy the formula ('), in the present invention, α _H is changed from the formula (') to the formula ('
Set to a value excluding those that satisfy the expression). In other words, if we exclude from formula ('formula) what satisfies formula ('formula), the formula becomes n _H + a _H = (2m+1)/2 (m: integer)..., and 'formula' becomes a _H = (: integer )...' becomes. The expression represents a recording pattern in which there is no line correlation of signals between adjacent tracks, but there is a line correlation of signals between every other track.

The recording/reproducing device according to the present invention is expressed by the formula (')
α _H is set to satisfy the following, and the specifications are determined from the formula. As an example of a system that records one field per track and satisfies the formula ' _a
There is = 1.0. The aforementioned VHS system PAL, SECAM
If a _H = 1.0 for a VTR, the tape speed is V _T
= 15.6 mm/S, the track pitch is T _P = 32 μm, and the sound quality and image quality are almost satisfactory for home use. Further, in the present invention, since the mounting angle of the two heads is 180° as in the conventional case, it can be easily switched to the case where a _H =1.5. Furthermore, the cylinder diameter is VHS style.
It is also very effective to select a _H =1.0 when trying to achieve higher density by making it smaller than a VTR. Note that the present invention is effective not only for a _H =1.0 but also for all a _H that satisfies the formula. FIG. 10 shows the recording pattern of PAL and SECAM VTR in the case of a _H =1.0 according to the present invention. As can be seen from FIG. 10, in this case, the horizontal synchronization signal of the adjacent track signal is located halfway behind the line of the main track signal. At this time, the interference of adjacent signals is determined by
can be mitigated by the techniques described in the issue,
Adjacent interference in color signals of NTSC and PAL signals can be removed using line correlation of carrier color signals. Also, Figure 11 shows PAL, SECAM
As shown above for VTR, the line numbers change in the case of NTSC signals as well, and the R and B color signals can be reproduced without problems.

However, the recording pattern (formula) according to the present invention
does not satisfy the formula, so discontinuity of color signals occurs during special reproduction of PAL and SECAM signals. Two methods for correcting this will be described below.

Fig. 11 shows a basic block diagram of an embodiment of one of the methods, Fig. 12 shows the waveforms and color signal relationships of each part in Fig. 11, and Fig. 13 shows the recording pattern of the color signal at this time (a _H = 1.0) and will be explained accordingly. In Figure 11, 1 to 13 are the 6th
Represents the same thing and performs the same actions as the diagram. 14,
24 is 1.5H (line) day line, 15,
23 is 1.0H day line, 16 and 22 are 0.5H
Delay line, 17 and 25 are switch circuits (SW), 18 and 26 are head switching signal input terminals,
19 and 27 are flip-flops, 20 and 28 are head switching signals, and 21 and 29 are output signals of the flip-flops 19 and 27, respectively, the waveforms of which are shown with the same numbers in FIG. Note that 29 has two states corresponding to the recording state, and these are shown as 29(1) and 29(2) in FIG. 12, respectively. The symbols in Figure 13 are the same as in Figure 10, but the line numbers represent those for the color signal, and the line numbers for the luminance signal represent the first
The figure remains as 0.

In FIG. 11, the luminance signal is processed in the same manner as in FIG. 6, and the recorded pattern is as shown in FIG. On the other hand, the output carrier color signal of the band filter 3 passes through the 1.5H delay line 14 to the a terminal of the switch circuit 17, passes through the 1.0H delay line 15 to the b terminal of the switch circuit 17, and passes through the 0.5H delay line 16. The signal is then guided directly to the c terminal of the switch circuit 17 and directly to the d terminal of the switch circuit 17. The switch circuit 17 is controlled by a head switching signal 20 (FIG. 12, 20) applied to the terminal 18 and a signal 21 (FIG. 12, 21) obtained by dividing the signal 20 in half by a flip-flop 19. Signal 20...high, signal 21...terminal a when high, signal 20...low, signal 21...terminal b when signal 21...high, signal 20...high, signal 21...terminal c when signal 21...low, signal 20...low, signal 21... When it is low, it is connected to terminals d and , respectively (12th
Figure 30). Therefore, as shown in FIG. 12, the output of the switch circuit 17 provides signals with delays of 1.5H, 1.0H, 0.5H, 0, 1.5H, . . . with respect to the input signal. The output color signal of the switch circuit 17 is guided to the frequency converter 5 and recorded in the same manner as in FIG. Now, truck-B, -A,-
If the color signals recorded in B, -A, -B... are delayed by 1.5H, 1.0H, 0.5H, 0, 1.5H..., respectively, then the color signal recording pattern is the first one.
It will look like Figure 3. In this way, the color signals are aligned in the recording pattern, and during reproduction, the interference signal received from the adjacent track is made into almost the same signal as the main signal, so that the influence can be reduced. Note that the relationship between the track and color signal delay is not limited to that shown in FIG. 11; the color signal delay order is 1.5H, 1.0H,
It is clear that the order of 0.5H, 0, 1.5H, etc. is sufficient.

Next, we will discuss the regeneration system. The reproduced carrier color signal converted to a low frequency signal, which is the output of the low frequency filter 9, is returned to its original frequency by a frequency converter 11.
After passing through the 0.5H delay line 22, 1.0H delay line 23, and 1.5H delay line 24, the terminals a, b, c, and d of the switch circuit 25 are connected as they are.
Each will be guided to The switch circuit 25 transfers the head switching signal 28 (FIG. 12) applied to the terminal 26 and the signal 28 to the flip-flop 27.
It is controlled by a signal 29 whose frequency is divided by 1/2 (29(1) or 29(2) in FIG. 12), and operates in the same way as the switch circuit 17 (28, 29(1), 32 or 2 in FIG. 12).
8, 29(2), 35). Switch circuit 17 during recording
control signals 20, 21 and switch circuit 2 during playback
Looking at the relationship between control signals 28 and 29 of No. 5, signal 2
0 and the signal 28 are determined to always be in the same phase with respect to the recording/reproducing track. That is, in Figures 12 and 13, when recording/reproducing on the B head (-B, -B, -B...), the level is high, and when recording/reproducing on the A head (-A, -A,
-A...) is at a low level. However,
The signal 21 and the signal 29 may be in the same phase during playback compared to the phase during recording (29(1) in FIG. 12, and may be in opposite phase (29(2) in FIG. 12). The connection of the playback switch circuit 25, the delay amount of the playback color signal, and the delay amount of the color signal for both recording and playback are shown in FIGS. 32 to 34 (playback (1)) and 35
~37 (Reproduction (2))). In the case of regeneration (1), the first
2. As shown in FIG. 34, the color signal delay for recording and reproduction is 2.0H between three fields, and one field is 0, which is repeated. In the case of playback (2), as shown in Figure 12, the color signal delay for both recording and playback is 1.0H between 3 fields, and 1.
Field 3.0H repeats. In either case, the difference in color signal delay between fields (tracks) is 2.0H, and the order of R and B of the reproduced color signal does not change, even if the heads are switched.
Since the colors are in the order of R, B, etc., the color discrimination circuit of the television receiver operates normally and can reproduce normal colors.

Next, the case of special playback will be described. During special playback, there are five cases in which color signal discontinuity may occur, as described in the explanation of FIGS. 7 to 9. These five cases will be explained. 1st
FIG. 4 is a diagram showing the amount of delay of each track signal when the color signal recording pattern as shown in FIG. 13 is specially reproduced with the reproduction trajectory as shown in FIGS. 7 to 9. 2
8 to 33 are the same as in FIG. 38-4
0 is static playback (Figure 7), 41 to 43 are high speed playback (Figure 8), and 44 to 46 are reverse playback (Figure 9) examples of playback tracks, recording color signal delay, and combined color of recording and playback. Indicates signal delay. Part 1 of the special playback mentioned above
In this case, it corresponds to the transition from -A track to -A track in Fig. 7, or from -B track to -B track, for example, Fig. 12 4.
3, the color signal will be delayed. As described above, in this case, since one head is performing one reproduction, the color signal delay switching is not performed during reproduction. As can be seen from the recording pattern in FIG. 13, since the color signals of every other track are lined up, continuity of the color signals can be obtained. In addition, in FIG. 14 43, the delay amount of the color signal changes by 1.0H when transitioning from -A to -A and from -B to -B. When reproducing the original pattern as shown in Figure 10, the order of the color signals is reversed, so at the time of transition, the color signal is 1.0H relative to the original signal.
The order of the color signals can be normalized by changing the . In the case of 2, from -B to -A in Figure 7,
This corresponds to the transition from -A to -B in FIG. 9, and the color signal is delayed as shown at 40 and 46 in FIG. 14. In this case, the color signal order is maintained by the same color signal delay switching as during normal reproduction. 3, -A in Figure 8
In the transition from -B to -B, the color signal is delayed as shown in FIG. 14 at 43. In this case, the color signal delay amount when switching heads changes by 1.0H. Since the color signal order is reversed when the original pattern (FIG. 10) is reproduced, it can be made normal by changing the delay amount by 1.0H. In the case of 4, in Figure 7 - from A -
B. In the transition from -B to -A in FIG. 9, the color signal lags as shown at 40 and 46 in FIG. 14. In this case as well, the amount of color signal delay when switching heads is
1.0H change and the color signal order is reversed when the original pattern is reproduced, so it can be made normal in this way. In the case of 5, in Figure 9 - from A -
When transitioning from A, -A to -A, -B to -B, a color signal delay occurs as shown in FIG. 14, 46. In this case as well, the reproduced color signal order can be made normal as in case 1. In FIG. 14, 29(1) is used as the switching signal 29 of the switch 25, but 29(2) is also the same.

Further, in the example of FIG. 11, the regeneration switch circuit 25
Although the output of the frequency converter 11 was directly connected to the d terminal of the d terminal, it may be connected via a 2.0H delay line. At this time, the reproduction color signal delay when connected to the d terminal in the reproduction of Figures 12 and 14 is
2.0H, and the color signal delay during recording and playback also increases by 2.0H, but the order of the color signals is not affected.

As described above, according to this method, not only can continuity of color signals be obtained during special playback, but also line correlation of color signals between adjacent tracks on the recording pattern can be obtained, thereby reducing adjacent interference. This is particularly effective for a carrier color signal that is a frequency modulated wave, such as a SECAM signal.

Next, a basic block diagram of an embodiment of another method is shown in FIG. 15, and an envelope of the reproduced signal during the special reproduction shown in FIGS. 7 to 9 is shown in FIG. 16, and will be explained. In FIG. 15, 1 to 13 represent the same things as in FIG. 6. 47 is 1H day line, 4
8 is an amplifier, 49 is an envelope detector, 50 is a pulse generator, 51 is an integrating circuit, 52 is an inhibit circuit, 53 is a flip-flop, 54 is a changeover switch, and 55 is a reproduction mode detection signal input terminal.
In addition, in FIG. 16, 56 indicates envelopes corresponding to FIG. 7 (static playback), 57 indicates envelopes corresponding to FIG. 8 (high-speed playback), and 58 indicates envelopes corresponding to FIG. 60 is the period during which the tracks are played back on the B head, and the letters -A, -B, -A, etc. in the envelope represent the tracks that are played back. Among the five cases of special reproduction described above, discontinuity occurs in the color signal in cases other than 2. In Figure 16,
56-A to-B4), 57-A
from -A and -B to -B1),
-From A-B3), 58 -From A-
A discontinuity occurs in the color signal when transitioning from -B to -B5) and from -B to -A4). In other words, discontinuity in the color signal always occurs where the envelope falls. 15th
The illustrated embodiment utilizes this phenomenon to obtain continuity of color signals. The operation will be explained below. During special reproduction, the carrier color signal that has been reproduced and restored to its original frequency by the frequency converter 11 is connected to one input of the changeover switch 54 and the 1H delay line 47.
guided by. The output carrier color signal of the 1H delay line 47 is amplified to a predetermined level by the amplifier 48 and guided to the other input of the changeover switch 54. On the other hand, the signal reproduced from the head 7 is guided to an envelope detector 49, the envelope of which is detected, and guided to a pulse generator 50, where a pulse corresponding to the point at which the envelope falls is generated. This pulse is transmitted to the integration circuit 51 and the inhibition circuit 52.
After passing through, it is led to a flip-flop 53. The integrating circuit 51 and the inhibiting circuit 52 function to prevent the flip-flop from malfunctioning due to unnecessary sound separation other than envelope depression. A signal for distinguishing between normal playback and special playback is applied to the terminal 55, and during special playback, a control signal whose polarity is inverted every time the envelope falls is obtained at the output of the flip-flop 53. With this control signal, selector switch 5
4 is controlled, and the carrier color signal which is the output of the frequency converter 11 and a signal delayed by one line thereof are alternately obtained as outputs. Therefore, the changeover switch 5
The output of 4 contains the dip in the envelope, i.e.
Each time the order of the color signals is reversed, a carrier color signal delayed by one line and a carrier color signal without delay are obtained alternately. Therefore, this output carrier color signal has continuity. In this way, continuity of color signals can be obtained. It should be noted that during normal reproduction, the output of the flip-flop 53 is set to a constant polarity by the signal at the terminal 55, and the switch 54 is always connected to either one without switching.

As described above, according to the present invention, continuity of the horizontal synchronization signal can be obtained during special playback, and
By applying some processing to the color signal,
It is also possible to obtain continuity of color signals in PAL and SECAM signals.

The above explanation has mainly been about a device in which two heads with azimuth degrees are placed opposite each other at 180 degrees, but the present invention is applicable to a device configured to provide an azimuth angle to patterns recorded on adjacent tracks. It is valid. For example, put four heads on the circumference.
The azimuth angle (same) between two heads arranged at 90° intervals and opposed at 180° is different from the azimuth angle (same) between the other two heads, and one quarter rotation of one head is made. Alternatively, a device in which one track is composed of 3/4 rotations can be considered. In addition, in a device that constitutes one track with 1/4 rotation, πR of equations (1) to (9)
In a device where one track is made up of 3/4 rotations, 3πR/2 may be substituted for πR.

[Brief explanation of the drawing]

Fig. 1 is a recording trajectory diagram of a helical scan VTR, Fig. 2 is a head trajectory diagram when performing special playback with a helical scan VTR, Fig. 3 is a diagram showing an example of a recording pattern with a _H = 1.5, and Fig. 4 is a diagram showing a recording pattern of 2 Figure 5 is a diagram showing an example of the recording pattern of the apparatus shown in Figure 4. Figure 6 is a basic block diagram of the signal processing of a home VTR. , Figures 7 to 9 are azimuth records.
Figures showing the head trajectories during static playback, high-speed playback, and reverse playback on a VTR, respectively; Figure 10 is a diagram showing an example of a recording pattern of a _H = 1.0 according to the present invention; Figures 11 and 15 are respectively shown in the book. A block diagram showing an example of a method for obtaining continuity of color signals when performing special reproduction of PAL and SECAM signals on a VTR having a recording pattern according to the invention. Figure 12 shows the waveforms and color signal relationships of each part of Figure 11. The diagrams shown in FIG. 13 are the color signal recording pattern diagrams in FIG. 11, and FIG.
The figure shows the relationship between waveforms and color signals of various parts when the pattern in Figure 13 is specially reproduced using the embodiment shown in Figure 11, and Figure 16 is the reproduced signal during special reproduction in Figures 7 to 9. FIG. 1... Input terminal, 2... Low-pass filter, 3... Bandpass filter, 4... Frequency modulator, 5... Frequency converter,
6, 12...Adder, 7...Head, 8...High-pass filter, 9...Low-pass filter, 10...Frequency demodulator, 1
1...Frequency converter, 14, 15, 16, 22, 2
3, 24...Delay circuit, 17, 25...Switching circuit.

Claims (1)

[Scope of Claims] 1. In an apparatus for recording and reproducing video signals by sequentially forming diagonal tracks on a recording medium using a plurality of heads arranged at equal distances on the same circumference, An azimuth angle is set for each of the plurality of heads so as to form an azimuth angle, n _H ⁺ a _H = (2m + 1)/2, where n _H is the number of signal lines formed on one track, a _H is on the recording trajectory. A video signal recording and reproducing device characterized in that a line deviation amount m from an adjacent track is set to a _H that satisfies an integer. 2. The video signal recording and reproducing device according to claim 1, characterized in that there are two heads arranged on the same circumference and are opposed to each other at an azimuth angle of 180°. . 3. The video signal recording and reproducing device according to claim 1, wherein one field of signal is recorded on one track, and a _H is set to satisfy a _H = (: integer). . 4. There are two heads placed on the same circumference, facing each other at an azimuth angle of 180°, so as to record one field signal on one track, a _H = The video signal recording and reproducing apparatus according to claim 1, wherein the video signal recording and reproducing apparatus is set to a _H that satisfies (: integer).