JPS6355274B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a video signal reproducing device that reproduces video signals by running a magnetic tape at a speed different from that during recording.

Using a pair of rotating magnetic heads with magnetic gaps having different azimuths and divided at an angle of 180°, a plurality of recording heads diagonal to the longitudinal direction of the magnetic tape, adjacent ones having different recording azimuths, and without a guard band are used. To form recording tracks, video signals are sequentially recorded so that signals of a predetermined period, such as field signals or frame signals, correspond to one recording track, and the magnetic tapes on which the video signals are recorded are placed on the pair of magnetic tapes described above. A high-density magnetic recording and reproducing system has been proposed in which reproduction is performed using a rotating magnetic head.

An example of such a recording/reproducing method will be explained with reference to FIG. In Figure 1, TP is a magnetic tape, Tc is a control signal track, Ta ₁ ,
Tb ₂ , Ta ₃ , Tb ₄ , Ta ₅ , Tb ₆ , Ta ₇ , Tb ₈ , Ta ₉
1 and 2 respectively show recording tracks that are oblique to the longitudinal direction of the magnetic tape TP, have different recording azimuths between adjacent tracks, and have no guard band. Each field signal of the video signal is sequentially recorded on each recording track. Note that h indicates the recorded horizontal synchronization signal. Also, α and β are magnetic tape TP, respectively.
and the scanning direction of a pair of rotating magnetic heads (with different magnetic gap azimuths and an angular division of 180°).

Then, one field of the video signal, that is, 262.5H (H is the horizontal period) is recorded on each recording track. Note that, in reality, several H worth of extra signals are recorded before and after that, but they are omitted from illustration. Furthermore, the starting ends or ending ends of adjacent recording tracks have a positional shift corresponding to a time of 3/4H of the video signal. There is a positional shift at the end corresponding to a time of 1 1/2H of the video signal. Further, the horizontal synchronizing signal h between adjacent recording tracks, that is, adjacent recording tracks having the same recording azimuth, has a positional shift corresponding to a time of 1/2H. The above-described positional deviation between the recording tracks is related to the running speed of the magnetic tape and the dimensions (drum diameter, etc.) of the magnetic tape guide drum device.

Now, there is a method of reproducing a magnetic tape on which a video signal is recorded by running it at a speed different from that during recording, that is, a variable speed mode reproducing method. This variable speed mode reproduction method includes still, fast (double speed), slow, reverse reproduction, etc.

Next, using the above-mentioned pair of rotating magnetic heads, 3
The mechanism will be explained with reference to FIG. 1, taking as an example the case of double speed and still playback. The scanning locus of one of the pair of rotating magnetic heads Ha and Hb in the case of 3x speed is as shown in S ₃ a, for example, a recording track Ta ₁ , the next recording track Tb ₂ , and two subsequent recording tracks. It comes to the position where it straddles the recording track Ta ₃ . Further, the other magnetic head Hb
The scanning trajectory of Tb ₄ is as shown in S ₃ b.
It comes to a position spanning the next recording track Ta ₅ and the next recording track Tb ₆ .

Therefore, in the magnetic head Ha, the signal from the recording track _Ta1 is reproduced in the first half of scanning, and the signal from the recording track _Ta3 is reproduced in the second half. Further, in the magnetic head Hb, the signal from the recording track Tb ₄ is reproduced in the first half, and the signal from the recording track Tb ₆ is reproduced in the second half.

In this case, as mentioned above, since the horizontal synchronization signal h between adjacent recording tracks has a positional shift corresponding to the time of 1/2H, the horizontal synchronization signal of the triple speed reproduction signal There is a jump of 0.5H at the time of transition, resulting in discontinuity.

In addition, in the case of still playback, the magnetic heads Ha and Hb
The scanning trajectories are the same as shown in Ss, and come to a position spanning, for example, the recording track Ta ₉ and the preceding recording track Tb ₈ .

Therefore, magnetic head Ha reproduces the signal from track Ta ₉ , and magnetic head Hb reproduces the signal from track Ta 9.
The signal from Tb ₈ is played back.

However, since the recording positions of signals between adjacent recording tracks are shifted by 3/4H as described above, signals from 0 to 263.25H are reproduced from the magnetic head Ha, that is, compared to normal reproduction. The signal portion at the end is played an extra 3/4H.
Similarly, from the magnetic head Hb, 261.75 to 525H
The signal up to this point is reproduced, that is, the beginning part is reproduced an extra 3/4H compared to the case of normal reproduction.

Therefore, the joint between the reproduction signals of the magnetic heads Ha and Hb is shifted by 1.5H, that is, by 0.5H.
Discontinuity occurs in the horizontal synchronization signal.

As described above, when a pair of magnetic heads scans across a plurality of recording tracks to demodulate the continuously reproduced signal and supply it to a television receiver, a horizontal synchronizing signal is generated when the recording track to be reproduced changes. Due to discontinuity (0.5H jump), skew occurs on the playback screen and the image becomes distorted.
Furthermore, when the data is reproduced across a large number of recorded tracks, skew occurs every time the recorded track changes, making it almost impossible to distinguish between images.

Therefore, a delay means having a delay amount selected according to the difference in misalignment of horizontal synchronizing signals between substantially adjacent recording tracks is provided so that the magnetic head can move from one recording track to substantially adjacent recording tracks during variable speed mode reproduction. Each time the recording track is moved, the reproduction signal from the magnetic head and the reproduction signal from the magnetic head are delayed by a delay amount (1/2H time in the above case) selected according to the difference in misalignment of the horizontal synchronization signal. ) and a delayed reproduction signal obtained by supplying the delayed reproduction signal to a delay means having a delay means having a delay means.

However, in the case of such variable speed mode playback, as can be seen from the scanning trajectory in Figure 1, the level (or S/N) of the playback signal changes from large to small to large, or from small to large to
It changes from small to small.

Therefore, auxiliary rotary magnetic heads Ha' and Hb' are provided for the above-mentioned pair of rotary magnetic heads (main rotary magnetic heads) Ha and Hb, respectively. If selected, a significant drop in S/N of the reproduced signal during variable speed mode reproduction can be avoided.

This head system will be explained below with reference to FIGS. 3 to 5. In Figure 3,
Ha and Hb are a pair of main rotating magnetic heads that rotate in the same plane and have different azimuths of the magnetic gap.
It has an angular division of θ ₁ =180°. Ha' and Hb' are auxiliary rotating magnetic heads that rotate in the same plane and have the same azimuth magnetic gap as the magnetic heads Ha and Hb, respectively, and have an angular division of θ ₁ = 180° and the corresponding main magnetic heads. There is an angular difference of θ ₂ with respect to Ha and Hb. This angular difference θ ₂ is determined by the auxiliary magnetic head Ha′,
Hb' is selected such that a scanning position shift corresponding to an integer H minute, for example 1H minute, occurs with respect to the corresponding main magnetic heads Ha and Hb, respectively. In addition, the auxiliary magnetic heads Ha', Hb' are different from the main magnetic heads Ha, Hb,
A step is provided so that the scanning locus is shifted by one track pitch. These rotating magnetic heads Ha, Ha', Hb, and Hb' are attached to a rotating drum RD of a magnetic tape guide drum device.

Furthermore, the magnetic heads Ha, Ha' and Hb, Hb' are actually first and second magnetic heads H _A , H _B which are composed of composite magnetic heads as shown in FIGS. 4 and 5, respectively.
It is formed in In Figures 4 and 5,
Ga, Ga′; Gb, Gb′ are magnetic heads Ha, Ha′, respectively;
This is the magnetic gap between Hb and Hb′. magnetic gap
Ga, Ga′ have the same azimuth, magnetic gap Gb,
Gb' has the same azimuth, but the magnetic gaps Ga, Ga' and the magnetic gaps Gb, Gb' have different azimuths. The width K of the magnetic gaps Ga, Ga', Gb, Gb' is approximately equal to the width of the recording track. The magnetic gaps Ga' and Gb' have a step K relative to the magnetic gaps Ga and Gb, respectively. Further, the distance D between the magnetic gaps Ga and Ga' and the distance D between the magnetic gaps Gb and Gb' are each an integer multiple of the distance between the horizontal synchronizing signals h recorded on the recording track of the magnetic tape TP in FIG. 1, for example 1. equals twice.

Next, with reference to FIG. 6, a description will be given of a video signal reproducing apparatus that uses such a head system and that corrects discontinuity in the reproduced horizontal synchronizing signal during variable speed mode reproduction. SW ₁ , SW ₂
is a switch circuit (actually a switch circuit using transistors) having fixed contacts a and b and a movable contact m, and is activated by a switching signal generated by a 30Hz signal generated as the rotating drum rotates. and can be switched in conjunction with each other. and,
The reproduction signal from the magnetic head Ha is sent to the reproduction amplifier 1a.
The reproduced signal from the magnetic head Ha' is transmitted through the regenerative amplifier _1a ' to the fixed contact a of the switch circuit SW 1, and the reproduced signal from the magnetic head Hb is transmitted to the fixed contact a of the switch circuit SW ₁ through the regenerative amplifier _1a '. At (b), the reproduced signal from the magnetic head Hb' is supplied to the fixed contact (b) of the switch circuit _SW2 .
Note that these reproduced signals are a mixed signal of an FM modulated luminance signal and a low frequency converted carrier color signal.

SW ₃ has fixed contacts c, d and a movable contact m,
This is a switch circuit (actually a switch circuit using transistors) that selects the higher level of the reproduced signals from the respective movable contacts m of the switch circuits SW ₁ and SW ₂ . 10 is a switching signal generating circuit that generates a switching signal for controlling this switch circuit _SW3 . This circuit 10 includes envelope detectors 2 and 3 to which the output signals of switch circuits SW ₁ and SW ₂ are supplied, respectively, a level comparator 4 that compares their detection outputs, and a hysteresis circuit to which the comparison outputs are supplied. It consists of 5.
Note that switching of the switch circuit _SW3 is performed within the horizontal blanking period.

The output of the switch circuit SW ₃ is supplied to the demodulation circuit 6, and the obtained reproduced video signal (luminance signal and inversely converted carrier color signal) is directly sent to the fixed contact e of the switch circuit SW ₄ with a delay amount of 0.5H. The signal is supplied to the fixed contact f through the delay circuit 7. Also, switch circuit
A movable contact m of SW ₄ is led out to an output terminal 9.
Also, the output of the FM demodulation circuit 6 is 0.5H of the horizontal synchronization signal.
The signal is supplied to a detection circuit 8 for detecting deviation, and a switch circuit SW ₄ is switched by the detection output thereof.

Now, in Fig. 6, there is no problem if the head system consists of only the main magnetic heads Ha and Hb (of course, the switch circuit SW ₃ and the switching signal generation circuit 10 are unnecessary here), When heads Ha' and Hb' are provided and reproduction signals are selected between the main magnetic heads Ha and Hb, the following problem arises. Let's explain this with reference to Figure 2.

Among the magnetic heads Ha, Ha′; Hb, Hb′ mentioned above,
For example, consider the reproduction signal in the case of first reproduction by scanning the magnetic heads Ha and Ha'. The recording tracks from which reproduced signals are obtained by scanning the magnetic heads Ha and Ha' are labeled Ta', Ta'', Ta as shown in Fig. 2A.
Then, the recording tracks with different recording azimuths between them become substantially equal to the guard band. Therefore, as shown in FIG. 2A, when one magnetic head Ha passes through the positions x ₁ →x ₂ →x ₃ →x ₄ →x ₅ and scans the recording tracks Ta', Ta'', Ta diagonally,
The other magnetic head Ha' is adjacent to the scanning locus of the magnetic head Ha and scans the recording tracks Ta', Ta'', and Ta obliquely with a delay of 1H minutes, until the position x ₁ of the magnetic head Ha mentioned above is reached. position corresponding to ~ _x5
It passes through x ₁ ′→x ₂ ′→x ₃ ′→x ₄ ′→x ₅ ′.

Then, each scanning position x ₁ of the magnetic heads Ha and Ha'
The levels of the simultaneously obtained reproduction outputs at ~ _x5 , _x1 '~ _x5 ' change as shown by the solid line and broken line, respectively, in FIG. 2B. Therefore, for example, the magnetic head Ha,
The reproduction output of Ha' is switched from the magnetic head Ha at the scanning position x ₂ (x ₂ ') to the magnetic head Ha' by the switch circuit SW ₃ shown in FIG. 6, and at the scanning position x ₄ (x ₄ ').
Then, the magnetic head Ha' is switched to the magnetic head Ha. In addition, the reproduction output of the magnetic head Ha is maximum,
When it is minimum, the reproduction output of magnetic head Hb is minimum,
Maximum.

Now, when the reproduction outputs of the magnetic heads Ha and Ha' are switched, at the scanning position x ₂ (x ₂ '), from the reproduction signal from the recording track Ta' by the magnetic head Ha, Since the signal is switched to the playback signal from the recording track Ta'',
There is a time lag of 0.5H in the reproduced signal. but,
Since switching between the magnetic heads Ha and Ha' at the scanning position x ₄ (x ₄ ') is performed within the same recording track Ta'', no time lag of 0.5H occurs in the reproduced signal.
In the case of still playback and slow playback, the manner in which the reproduction signal is shifted by 0.5H due to switching of the magnetic heads Ha and Ha' is opposite to that described above.

Therefore, if a time lag of 0.5H occurs in the reproduced signal due to switching of the magnetic heads Ha and Hb, a detection output is obtained from the detection circuit 8, and the switch circuit
Switching of SW ₄ is performed.

Now, as shown in Fig. 2, in the case of fast playback, when considering the playback outputs of the magnetic heads Ha and Ha', when the switch circuit SW ₃ switches from Ha to Ha' (in addition, in still and slow playback, If Ha′→
When switching Ha), a signal shift of 0.5H occurs, so in this case, switch circuit _SW4 is switched, but at this time the reproduction output of magnetic head Ha is 0.5H of the reproduction output of magnetic head Ha'. When the signal is switched to a signal delayed by a certain amount of time, and when the magnetic head Ha
The signal delayed by 0.5H minutes is sent to the magnetic head.
There are cases where the output is switched to Ha' playback output.

That is, in FIGS. 7A to 7D, the reproduction output of the magnetic head Ha is transferred to the magnetic head by the switch circuit _SW3 .
Switch circuit when switching to Ha′ playback output
The video signals supplied to the fixed contacts e and f of SW ₄ are shown, and FIG.
7B and 7D are delayed video signals Ha and DL, respectively, which are delayed by a time of 0.5H of the video signals based on the reproduction outputs of the magnetic heads Ha and Ha' obtained at the fixed contact f, respectively. Ha' and DL are shown respectively.

Thus, when the reproduction output of the magnetic head Ha is switched to the reproduction output of the magnetic head Ha' by switching the switch SW ₃ , the movable contact m of the switch circuit SW ₄ changes from the fixed contact e to the fixed contact f. The output of the output terminal 9 when switched is as shown in FIG. 7E, and the output of the output terminal 9 when the movable contact m of the switch circuit SW ₄ is switched from the fixed contact f to e.
The output is as shown in FIG. 7F.

There is no problem in the case of Fig. 7F, but in the case of Fig. 7E, next to the video signal of a certain 1H period, the latter part of the video signal is played again, and then the second half of the video signal of the other 1H period is played back. Since the second half of the video signal is played back, the signal will be distorted during that 1H period.
Noise occurs on the playback screen. This is demodulation circuit 6
Simply provide one magnetic head Ha,
This is due to the fact that one of the reproduced outputs of Ha' (or Hb, Hb') is switched and supplied, and its demodulated output is delayed or advanced by a time of 0.5H.

In view of this, the present invention relates to a video signal reproducing device that reproduces video signals by running a magnetic tape at a speed different from that during recording, and which avoids a drop in the level (or S/N) of the reproduced signal. The present invention aims to propose a system that can correct discontinuities in the reproduced horizontal synchronizing signal and also correct discontinuities in the video signal section.

An embodiment of the present invention will be described below with reference to FIG. 8. In FIG. 8, parts corresponding to those in FIG. 6 described above are given the same reference numerals, and redundant explanation will be omitted.

This video signal reproducing device has a plurality of recording tracks arranged diagonally with respect to the longitudinal direction, adjacent tracks have different recording azimuths, and horizontal synchronization signal recording positions are shifted by a predetermined amount (in this example, 1 /
Positional shift corresponding to 2H minutes) As if shifted,
Predetermined period of video signal (field period in this example)
Magnetic tape TP, which sequentially records each signal,
It is designed to perform playback by running at a speed different from that during recording.

In such a video signal reproducing device,
As shown in FIGS. 3 to 5, the azimuth of the magnetic gap is the same, the scanning locus is shifted by one recording track, and the scanning time difference is equivalent to a predetermined integer (in this example, 1) times the horizontal period. The azimuth of the magnetic gap is the same as that of the first reproducing magnetic head H _A consisting of the main and auxiliary magnetic heads Ha and Ha', the scanning locus is shifted by one recording track, and the horizontal period is a predetermined integer (in this example, 1) A second reproducing magnetic head consisting of main and auxiliary magnetic heads Hb and Hb', which have a scanning time difference equivalent to twice that of the first reproducing magnetic head H _A and whose azimuth of the magnetic gap is different from that of the first reproducing magnetic head H A.
H _B , two reproduction signals from each of the main and auxiliary magnetic heads Ha, Hb; Ha', Hb' of the first and second reproduction magnetic heads H _A and H _B , and the reproduction signal of one of them selected by switching. The amount of delay corresponding to the recording position shift of the horizontal synchronization signal between adjacent recording tracks (0.5H in this example)
switching a total of three reproduction signals delayed by a time of 1 minute) to the main and auxiliary magnetic heads Ha, Hb of the first and second reproduction magnetic heads H _A and H _B ;
A switching means 20 is provided for outputting the reproduced signal having a higher level among the reproduced signals Ha' and Hb' while maintaining the continuity of the horizontal synchronizing signal and the video signal portion.

The reproduction signal of magnetic heads Ha and Hb is a switch circuit.
After being switched by SW ₁ , it is supplied to the demodulation circuit 6. The reproduced signals from the magnetic heads Ha' and Hb' are switched by a switch circuit _SW2 and then supplied to a demodulation circuit 6'. When the video signal recorded on the magnetic tape TP is a mixed signal of an FM modulated luminance signal and a low-frequency conversion carrier color signal, these demodulation circuits 6 and 6' are connected to a signal separation circuit, an FM demodulation circuit, and a high-frequency conversion circuit. Consists of circuits. Note that if the video signal is a black and white video signal, only the FM demodulation circuit is sufficient as the demodulation circuits 6 and 6'.

Next, the switching means 20 will be explained. A switch circuit having fixed contacts c and d and a movable contact m (actually a switch circuit using transistors)
SW ₄ and SW ₅ are provided, each fixed contact c is connected to the output side of the demodulation circuit 6, and each fixed contact d is connected to the output side of the demodulation circuit 6'.
connected to the output side of the Reference numeral 10 designates a switching signal generating circuit having the same configuration as that shown in FIG. 6, and the switching signal from this circuit switches the switch circuit _SW4 , and the movable contact m has the switch circuits _SW1 ,
Among the reproduced signals on the output side of SW ₂ , the reproduced signal with a higher level is output and supplied to the detection circuit 8 similar to that shown in FIG. 6, and its detection output is sent to the logic control circuit 1.
2. Further, the switching signal from the switching signal generation circuit 10 is directly supplied to the control circuit 12.

Further, the switch circuit SW ₅ is switched by the first control signal from the control circuit 12, and the output from the movable contact m is sent to the delay circuit 7 having a delay amount corresponding to 0.5H minute. Supplied.

A switch circuit (actually a switch circuit using transistors) SW ₆ is provided, and its fixed contact c
The output of the demodulation circuit 6 is sent to the fixed contact f to the delay circuit 7.
The output of the demodulation circuit 6' is supplied to the fixed contact d, and is controlled by the second control signal from the control circuit 12 to the output terminal 9 from which the movable contact m is derived. Second reproducing magnetic head H _A ,
Each _main and auxiliary magnetic head Ha, Ha′; Hb,
Among the Hb' reproduction signals, the reproduction signal with a higher level is output while maintaining the continuity of the horizontal synchronization signal and the video signal.

A still/slow reproduction/fast reproduction discrimination signal is supplied to the control circuit 12 from a control signal input terminal 13.

The switch circuits SW ₅ and SW ₆ are the control circuit 1.
Control is performed by the first and second control signals from No. 2 based on the following logical formula. Let the output of the switching signal generation circuit 10 be A, and
When A, the movable contacts m of the switch circuit SW ₄ are switched to the fixed contacts c and d, respectively. The output of the detection circuit 8 is D (when the horizontal synchronization signal jumps by 0.5H),
D (when not present), the discrimination signal to input terminal 13 is M
(for example, during still or slow playback), (for example, during fast playback).

Thus, the movable contact m of the switch circuit SW ₅ is switched to the fixed contact c when AD+A+ . . . (1), and vice versa, the movable contact m of the switch circuit SW 5 is switched to the fixed contact d. Also, the movable contact m of switch circuit SW ₆
is switched to c, f, and d when A(MD)...(2) A()+(MD)...(3) A()...(4). Here, indicates the sign of exclusive OR.

According to the reproducing apparatus of FIG. 8, since the signal of FIG. 7D exists before the switching time, the signal of FIG.
The discontinuity of the video signal from Ha→Ha′・DL like this is eliminated.

Next, another embodiment of the present invention will be described with reference to FIG. 9. In FIG. 9, parts corresponding to those in FIG. 6 and FIG. do. In this embodiment, the present invention is applied to a video signal reproducing device having a dropout compensation circuit, and 15 is a 1H delay circuit therefor, 6 is a subsequent demodulation circuit (FM demodulation circuit), and SW ₇ and SW ₈ are This is a switch circuit (actually a switch circuit using transistors) for that purpose. Switch circuit SW ₇
has fixed contacts g, h and a movable contact m, and the switch circuit SW ₈ has fixed contacts i, h and a movable contact m. The reproduction signals of the magnetic heads Ha and Hb are switched by switch circuit SW ₁ and then switched by switch circuit SW _7.
is supplied to the fixed contact g. Also, magnetic head
The reproduced signals Ha' and Hb' are switched by the switch circuit SW ₂ and then supplied to the fixed contact i of the switch circuit SW ₈ . The output of the delay circuit 15 is then supplied to each fixed contact h of the switch circuits SW ₇ and SW ₈ and to the demodulation circuit 6.

6' is another demodulation circuit (FM demodulation circuit).

Next, the switching means 20 will be explained. Switch circuit SW ₉ with fixed contacts r, s and movable contact m
are provided, and the fixed contacts r and s are respectively switch circuits.
It is connected to each movable contact m of SW ₇ and SW ₈ . The output from movable contact m of switch circuit SW ₉ is delay circuit 1
5, is commonly supplied to the demodulation circuit 6' and the detection circuit 8. This switch circuit _SW9 is switched and controlled by a switching signal from a switching signal generating circuit 10 having the same configuration as that shown in FIG.

The switching signal from the switching signal generation circuit 10, the detection output of the detection circuit 8, and the discrimination output of the control input terminal 13 are supplied to the logic control circuit 12.

A switch circuit SW ₁₀ is provided having fixed contacts t, u, v and a movable contact m. Then, the output of the demodulation circuit 6 is connected to the fixed contact t, the output of the demodulation circuit 6' is connected to the fixed contact u, and the output of the demodulation circuit 6' delayed by the 0.5H delay circuit 7 is connected to the fixed contact v. supplied respectively. The movable contact m is led out to the output terminal 9.

This switch circuit SW ₁₀ is switched and controlled by the first to third control outputs of the logic control circuit 12 based on the following logical formula. Note that the first control signal is circulated to the control circuit 12 via a monostable multivibrator 14 with a time width of 1H.

The output of the switching signal generation circuit 10 is A,
When A, the movable contact m of the switch circuit SW ₉ is switched to the fixed contacts r and s, respectively. The output of the detection circuit 8 is D (when there is a 0.5H jump in the horizontal synchronization signal), (when there is no jump), and the discrimination signal to the input terminal 13 is M (during still or slow playback), (during fast playback). .

Control circuit 12 to monostable multivibrator 1
The signal (trigger signal) N supplied to 4 is as follows: N=D(MA) (5). Let Q be the output of the monostable multivibrator 14. Movable contact m of switch circuit SW ₁₀
is switched to fixed contact t when the first control signal is Q (high level), and switched to fixed contact u when the second control signal is , and switched to fixed contact v. This occurs when the third control signal is D()+D(MA)...(6).

Next, in the playback device shown in FIG.
Magnetic head in the case of first playback shown in the figure
The operation when switching from the reproduction output of Ha to the reproduction output of magnetic head Ha' will be explained with reference to FIG. 10A and 10C show the output of the fixed contact u of the switch circuit SW _10. By switching the switch circuit SW ₉ , the video signal Ha (FIG. 10A) based on the reproduced output of the magnetic head Ha is transferred to the magnetic head. This shows that the signal has been switched to the video signal Ha' (FIG. 10C) based on the reproduced output of Ha'. FIG. 10B shows the output of the fixed contact t of the changeover switch circuit SW ₁₀ , which is a video signal Ha.DL _1H delayed by 1H of the video signal Ha based on the reproduction output of the magnetic head Ha. FIG. 10D shows the output of the fixed contact v of the switch circuit SW ₁₀ , and shows the video signal Ha' delayed by 1/2H of the video signal Ha' based on the reproduction output of the magnetic head Ha' in FIG. 10C.
DL _1/2H .

Thus, the switch circuit is connected to the output terminal 9.
By switching the movable contact m of SW ₁₀ in the order of fixed contacts u→t→v, a horizontal synchronizing signal HD and a continuous video signal of the video signal portion as shown in FIG. 10E are obtained.

According to the present invention described above, in a video signal reproducing device that reproduces video signals by running a magnetic tape at a speed different from that during recording, it is possible to avoid a decrease in the S/N of the reproduced signal, It is possible to obtain something that can correct discontinuities in the reproduced horizontal synchronization signal and also can correct discontinuities in the video signal section.

[Brief explanation of the drawing]

Fig. 1 is a pattern diagram showing the pattern of the recording track of the magnetic tape, Fig. 2 is a pattern diagram and characteristic curve diagram showing the positional relationship between the recording track and the magnetic head, and Fig. 3 is a layout diagram showing the arrangement of the magnetic head. ,
4 and 5 are front views showing the first and second magnetic heads, FIG. 6 is a block diagram showing a video signal reproducing device used to explain the present invention, and FIG. 7 is a time diagram of the video signal. 8 and 9 are block diagrams showing different embodiments of the present invention, and FIG. 10 is a diagram showing a time chart of a video signal. TP is a magnetic tape, H _A and H _B are first and second reproduction magnetic heads, Ha and Hb are main magnetic heads,
Ha' and Hb' are auxiliary magnetic heads, and 20 is a switching means.

Claims (1)

[Claims] 1 A video signal is recorded every predetermined period on a plurality of recording tracks arranged diagonally with respect to the longitudinal direction, so that the recording azimuth differs between adjacent tracks and the recording position of the horizontal synchronization signal deviates from the alignment by a predetermined amount. In a video signal reproducing device that reproduces a sequentially recorded magnetic tape by running it at a speed different from that during recording, the azimuth of the magnetic gap is the same and the scanning locus is equal to one of the above recording tracks. A first reproducing magnetic head consisting of a main and auxiliary magnetic head having a scanning time difference corresponding to a predetermined integral multiple of the horizontal period and a magnetic gap having the same azimuth and a scanning locus corresponding to one recording track. a second reproducing magnetic head comprising a main and auxiliary magnetic head having a scanning time difference corresponding to a predetermined integral multiple of the horizontal period and having a magnetic gap having a different azimuth from that of the first reproducing magnetic head; After extracting one of the signals from the main and auxiliary magnetic heads of the first or second reproducing magnetic head, respectively, or by switching, one of the signals is obtained directly and through two parallel demodulation circuits with delay means interposed. A total of three signals, the two reproduced signals that are switched and the reproduced signal that is delayed by the amount of delay corresponding to the recording position shift of the horizontal synchronization signal between the adjacent tracks of the selected one of the reproduced signals, are shifted from the recording position. Switching based on the detection output, the reproduction signal having a higher level among the reproduction signals of each main and auxiliary magnetic head of the first and second reproduction magnetic heads is output while maintaining the continuity of the horizontal synchronization signal and the video signal part. 1. A video signal reproducing device characterized by being provided with a switching means for switching.