JPH02279089A - Special reproducer for vtr - Google Patents

Abstract

PURPOSE:To attain stable performance and to reduce cost by switching whether or not a video signal is retarded by 1/2H in response to a discontinuity detection signal and switching whether a luminance signal of the video signal is retarded by 1H or a color signal is retarded by 1H in response to the reproducing direction signal and the state of the detection signal. CONSTITUTION:In the case of special reproduction of a video signal recorded at a tape speed being a half the standard speed, a discontinuity detection means 6 detects the discontinuity of a reproduced video signal or a horizontal synchronizing signal, a 1/2 delay switching means 21 switches whether or not the video signal is subjected to 1/2H delay and skew distortion is prevented so as to make the horizontal synchronizing signal continuous. In response to a level of the detection signal and a signal representing the reproducing direction, a circuit 10H retarding normally a luminance signal by 1H is switched into a color signal to match the phase of the color signal. Thus, the 1H delay circuit 10H is used effectively to keep the consecution between the horizontal synchronizing signal and the color signal and the same effect is obtained while reducing the cost.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a video signal recorded at a standard tape speed of 172 tape, which is reproduced at a speed different from the recording speed.
This invention relates to a special playback device for an AL, SEC, or AM VTR.

(Summary of the Invention) This invention provides a television that alternately transmits two types of color signals for each horizontal scanning line (hereinafter referred to as "line"), and forms one cycle of the color signal with signals for two consecutive lines. A helical format that conforms to the PAL format or SECAM format and is recorded so that the recording positions of consecutive horizontal synchronization signals at equal intervals on the video track are aligned perpendicular to the video track when recording at standard speed. scan VT
In a special playback device for a VTR which is also capable of playing back tapes recorded at the standard tape speed of 172.

When performing special reproduction of a video signal recorded at a tape speed that is 1/2 of the standard speed, a discontinuity in the reproduced video signal or its horizontal synchronization signal is detected and the video signal is switched to be delayed by 1/2H or not. By switching between delaying the luminance signal by 1H or delaying the chrominance signal by 1H depending on the level of the detection signal and the signal indicating the reproduction direction and matching the phase of the chrominance signal, continuity between the horizontal synchronization signal and the chrominance signal is maintained. This is to obtain an image with less noise and disturbance.

[Conventional technology]

Hereinafter, as a general rule, H indicates a line or its period (time), and 6-body video track (hereinafter referred to as "track")
Indicates the length (space) of one line recorded above.

Figures 5 and 6 are schematic development views of video signal patterns recorded on a magnetic tape using the helical scan method at standard speed and 1/2 tape speed, respectively, when viewed from the base side. Arrow T and arrow H indicate the traveling direction of the tape and head, respectively.

Generally, in a helical scan VTR, the recording position of the horizontal synchronizing signal of the video signal is aligned perpendicular to the track when recording at standard speed, as shown in FIG.
They are arranged in "H" arrangement.

Cue (fast playback), Reverse (reverse playback), Review (
When performing special playback (also called trick play) such as high-speed reverse playback, the dashed line (5
As shown by the double-speed cue) or the dashed-dotted line (three-times speed review), the head will cross multiple tracks, and there will be no problem if the heads are lined up in H as shown in Figure 5. If they are not arranged in an H arrangement as shown in the figure, the recording position of the horizontal synchronization signal will be shifted, causing the horizontal synchronization to be lost and the monitor screen to be distorted (skew distortion).

In a VTR that is arranged in H format at standard speed.

When recording at a tape speed of 172 or 1/3 of the standard speed (hereinafter referred to as "half speed" or "1/3x speed"), 1
/If the speed is 3x, it will be H-lined, but if it is half-speed, it will not be H-lined, as shown in Figure 6.

When performing special playback of such a tape, in the case of the NTSC system, the subcarrier is divided into two at right angles by the engineering signal and the Q signal, which are synthesized from two types of color signals, that is, the B-Y signal and the R-Y signal.
Since the signal is phase modulated and directly combined with the luminance signal to form a composite signal, the reproduced video signal only needs to be delayed by 1 to compensate for the deviation of the horizontal synchronization signal.

However, television systems, such as the PAL system and the SE system, transmit two types of color signals alternately line by line and form one cycle of the color signal with signals for two consecutive lines.
There is a CAM method.

In the PAL system, there are two types of color signals: a color signal consisting of a B-Y signal and a R-Y signal, and a color signal consisting of a B-Y signal and a Y-R signal. The carrier wave is quadrature two-phase modulated, and in the SECAM system, B
Using two types of color signals, the -Y signal and the RY signal, a subcarrier is alternately frequency modulated (FM) L for each line, and each is synthesized with a luminance signal to form a composite signal.

In such a television system, the monitor delays the color signal separated from the input composite signal by 1H, and mixes the color signal that is not delayed and the color signal that is delayed by 1H (delayed).
) The B-Y signal and the R-Y signal must be reproduced from the color signal.

That is, in the PAL system, the through signal and the delayed signal are added to obtain the BY signal, and after subtraction, the phase is inverted for each line to obtain the RY signal. Also, SECAM
In this method, the through signal and the delayed signal are exchanged line by line to obtain the BY signal and the RY signal.

Therefore, a VT that plays back recordings that are not arranged in H order.
If the R special reproduction device does not correct the delay and also match the phase of the color signal (2 lines, 1 cycle) as described above, the monitor will not be able to reproduce the color signal correctly and the color will disappear. There are cases where this happens.

In the developed diagrams shown in Figures 5 and 6, one track is recorded with one field of video signals, and adjacent tracks are recorded with heads with opposite azimuth angles (hereinafter referred to as "azimuth"), and are horizontally synchronized. The numbers 1 to 625 attached to each line partitioned by signals indicate the line number, and the arrows whose directions are reversed indicate the difference in phase of the color signals.

Due to the 1:2 interlace, the 313th line is divided into two, with the first half (313U) being the first field and the second half (31U) being the first field.
3D) belongs to the second field.

Furthermore, the trajectory of the head during 5x speed cue or 3x speed review is as shown by a broken line or a two-dot chain line, and the head has the same azimuth as when recording start track a or e, respectively. , track a
, c, e, etc. are reproduced, but the recordings of reverse azimuth tracks b, d, etc. are not reproduced.

In the case of standard recording shown in Figure 5, even if the head moves to track f1 + Q - + Q during 5x speed cue, the horizontal synchronization signal of the reproduced video signal is continuous, and the phase of the color signal is also Since they are aligned (alternately reversed), the monitor image is stable. The same is true for triple-speed review.6 However, in the case of half-speed recording shown in Figure 6, the recording position of the horizontal synchronization signal is 0.2 between adjacent tracks
5h, and 0.5 times that between adjacent tracks with the same azimuth.
It is off by h.

Therefore, in 5x speed cue or 3x speed review, the head is on track a-+c-+e or track e-+8-)
When the track changes by moving to a, the horizontal synchronization signal of the reproduced video signal becomes discontinuous, and the monitor image loses horizontal synchronization at the discontinuity, causing the vertical line to become bent (skew distortion). A skew jump occurs.

Furthermore, the phase of one color signal becomes discontinuous, and colors may disappear depending on the TV monitor.

FIG. 8 is a circuit diagram showing a conventional example of a device for preventing this skew jump, and shows the states of switches 20, 21, and 22 when their control signals are at L°.

The heads IA are arranged at axially symmetrical positions on the same circumference of a rotary head (not shown) and have mutually opposite azimuths.

1B alternately plays the video signal every time the rotating drum rotates 180 degrees, and at the same time detects the phase of the rotating drum.
During reproduction by the azimuth head IA or -azimuth head 1B, a switching pulse (SW pulse) of H° or °L is output, respectively.

The video signals reproduced by heads iA and iB are amplified by preamplifiers 2A and 2B, respectively, and then selected by a switch 20 that is switched in response to a switching pulse, and output as a continuous video signal to the next stage.

During normal reproduction (reproduction at the same speed as the recording speed), the switches 21 and 22 do not operate and remain in the illustrated degree L degree.

Therefore, the luminance signal and color signal (hereinafter referred to as "Y signal" and "C signal" respectively) that constitute the video signal are as follows:
The signals are respectively input to a Y signal processing circuit 3 and a C signal processing circuit 4, and after being subjected to processing such as demodulation, are combined into a composite signal by a Y/C mixing circuit 5, and outputted via a switch 21.

The Y signal processing circuit 3 sends a part of the Y signal being processed to the 1H delay circuit 9 and delays it by 1H, thereby canceling noise by taking an H correlation with the Y signal currently being processed.

Furthermore, if a dropout occurs in the Y signal currently being processed, the Y signal is switched to the Y signal delayed by 1H to prevent dropout from appearing on the monitor image.

In this way, the 1H delay circuit 9 is used to improve the quality of the reproduced monitor image.

In the case of special playback of half-speed recording, the skew detection circuit 6 inputs the Y signal output from the Y signal processing circuit 3 or the horizontal synchronization signal included in the Y signal, and whenever it detects discontinuity in the horizontal synchronization signal, Outputs a detection signal whose level is inverted.

The switch 21 switches Y/C according to the level of the detection signal.
It is switched whether the composite signal outputted by the mixing circuit 5 is passed through (no delay) or delayed by 0.5 h by the 1/2 delay circuit 7.

The exclusive OR circuit 12 is at °H during forward playback.

During reverse playback, the CUE/REV signal, which is at L°, and the detection signal output from the skew detection circuit 6 are input, and their exclusive OR is performed using a T-FF (toggle flip-flop).
The T-FF circuit 13 outputs a signal whose level is inverted every time the input signal rises.

The switch 22 switches, depending on the level of the output signal of the T-FF circuit 13, whether to pass the C signal output from the C signal processing circuit 4 or to delay it by 1H by the 1H delay circuit 8.

FIG. 9 and FIG. 10 are waveform diagrams showing each signal at the time of 5x speed cue and 3x speed review of half-speed recording, respectively, and will be explained in detail later in the example, but (A) shows the switching pulse. , (B) is a continuous reproduction video signal outputted by the switch 20, (C) is a detection signal, and (D) is a logic output of the exclusive OR circuit 12.

(E) shows the FF outputs of the T-FF circuit 13, respectively.

As a result, the 5x speed queue (
3x speed review), the Y signal is c, h, which is shifted by 0.5H from the start track a(e).
When (c, z) is being reproduced, since the detection signal is °H°, the composite signal is delayed by 0.5H, and the horizontal synchronization signal is continuous and no skew distortion occurs.

Regarding the C signal, in the case of 5x speed cue, while playing tracks a, c, e and f, h, j, the delay time is 0.0.5H, LH, 1, 5H, O, respectively. In the case of 3x speed review, tracks e, Q, a and
While playing z and x, the delay time is 0.1.
5H, LH, 0, 5H, O, and the phase shift occurs after detecting the discontinuity of the horizontal synchronization signal.
within this range, and no problems such as color fading on the monitor image occur.

[Problem to be solved by the invention]

Two 1H delay circuits 8.9 are used in this conventional circuit.

However, in the case of standard playback of standard recording, half-speed recording (where the recording speed and playback speed are the same), and special playback of standard recording arranged in H arrangement, the phases of the horizontal synchronization signal and the C signal are continuous. Therefore, the 1H delay circuit 8 is never used.

On the other hand, in the case of special playback of half-speed recording that is not arranged in H alignment, it is inevitable that noise bars will appear on the monitor screen when the head moves between tracks, so the LH delay circuit 9 is activated. However, the effect is not very noticeable.

This invention has been made in view of the above points, and includes:
By using two 1H delay circuits, the same effect as using two 1H delay circuits can be obtained while reducing costs, and the purpose is to stabilize performance and reduce costs.

[Means to solve the problem]

In order to achieve the above object, the present invention alternately transmits two types of color signals for each line (horizontal scanning line), and forms one cycle of the color signal with signals for two consecutive lines. In accordance with the television system, adjacent tracks each recording one field of video signals are recorded and played back alternately using heads with opposite azimuths using a plurality of heads installed on the same circumference of a rotating drum, and at a standard speed. A helical scan VTR in which recording is performed so that the recording positions of consecutive horizontal synchronizing signals are aligned perpendicular to the track at equal intervals on the track, and are recorded at a tape speed that is half the standard speed. A special playback device for a VTR capable of playing back played tapes includes a discontinuity detection means for detecting discontinuity in the played video signal or its horizontal synchronization signal and outputting a detection signal; 1/2H delay switching means for switching whether or not to delay the video signal by 1/2H in accordance with a detection signal to be output; and a reproduction direction signal indicating whether the reproduction direction is forward or backward, and a detection signal. Accordingly, a 1H delay switching means is provided for switching between delaying the luminance signal of the video signal by 1H and delaying the color signal by 1H.

[For production]

With the above configuration, when performing special reproduction of a video signal recorded at half the tape speed of the standard speed, the present invention detects discontinuities in the reproduced video signal or its horizontal synchronization signal and reproduces the video signal. It switches whether or not to delay the signal by 1/2H to ensure that the horizontal synchronization signal is continuous to prevent skew distortion.

In addition, depending on the level of the detection signal and the signal indicating the reproduction direction, the circuit that normally delays the luminance signal by 1H is switched to the color signal and the phase of the color signal is matched.
By effectively using the delay circuit to maintain the continuity of the horizontal synchronization signal and color signal, it is possible to obtain the same effect while reducing costs.

〔Example〕

Hereinafter, this invention will be explained based on examples.

1 and 2 are circuit diagrams showing the first and second embodiments of the present invention, respectively, and the same parts or parts having the same function as the conventional example shown in FIG. - symbol or associated symbol.

In addition, the switches 20 to 24 all have a control signal of L.
The state at ° is shown.

In the first embodiment shown in FIG. 1, video signals reproduced by heads lA and iB having opposite azimuths are amplified by preamplifiers 2A and 2B, respectively, and then output to input terminals of a switch 20. .

The Y (luminance) signal and C (color) signal that constitute the (continuous) video signal output from the output terminal of the switch 20 controlled by the switching pulse are sent to the Y signal processing circuit 3 and the C signal processing circuit 4, respectively. input.

The 1H delay circuit 10H is made of, for example, a glass delay element (ultrasonic delay element) that can cover up to a high frequency range, and the common terminals of the switches 23 and 24 are connected to the input and output sides, respectively.

These switches 23 and 24 constitute a 1H delay means together with the switch 22, and are controlled by the output signal of the T-FF circuit 13, but are held on the L° side except during special playback of half-speed recording.

A pre-demodulated V signal (FM signal) from the Y signal processing circuit 3 and a high frequency converted C signal from the C signal processing circuit 4 are input to the input terminals of the switch 23, respectively. switch 2
The output terminals of 4 are connected to the Y signal processing circuit 3 and one input terminal of the switch 22, respectively.

The non-delayed (through) C signal output from the C signal processing circuit 4 is input to the other input terminal of the switch 22;
The switched C signal is outputted to the Y/C mixing circuit 5 from its output terminal.

Therefore, the 1H delay circuit 10H is normally connected to the Y signal processing circuit 3, and the 1H delay circuit 10H of the conventional example (FIG. 8) is connected to the Y signal processing circuit 3.
Similarly, it is used for H correlation noise cancellation and dropout prevention, and the Y signal processing circuit 3 performs processing such as demodulation on the input V signal, and then outputs it to the Y/C mixing circuit 5.

Further, the C signal processing circuit 4 performs processing such as frequency conversion on the input C signal, and then converts the input C signal into a Y/C signal via a switch 22.
Output to mixing circuit 5.

The Y/C mixing circuit 5 receives V input from the Y signal processing circuit 3.
The signal and the C signal input from the output terminal of the switch 22 are mixed and output as a composite signal.

In the case of special playback of half-speed recording, when the skew detection circuit 6, which is a discontinuity detection means, detects discontinuity in the V signal input from the Y signal processing circuit 3 or the horizontal synchronization signal included in the V signal, the level A detection signal inverted from H° to 'L-' or from L° to 'H° is output to the exclusive OR circuit 12 and the switch 21 as a control signal.

The exclusive OR circuit 12 receives a reproduction direction signal C U E /' indicating whether the reproduction direction is the forward direction °H° or the backward direction °L.
The RE V signal and the detection signal output from the skew detection circuit 6 are exclusive-OR'ed and output to the T-FF circuit 13.

The T-FF circuit 13 outputs to the switches 22 to 24 a signal whose level is inverted depending on the rising edge of the signal input from the exclusive OR circuit 12.

When the signal output from the T-FF circuit 13 is H°, the C signal output from the C signal processing circuit 4 is sent to the switch 23. Delayed by 1H via LH delay circuit 10H and switch 24, °L''
In this case, the signals are output as through (non-delayed) C signals to the Y/C mixing circuit 5 via the switches 22, respectively.

The signal waveforms of various parts during special playback of half-speed recording are the same as the signal waveforms of the conventional example shown in FIGS. 9 and 10.

In the case of the 5x speed cue shown in FIG. 9, while the switching pulse shown in FIG.
While the switching pulse is °L, the video signal reproduced from track fvh+j by the -azimuth head 1B is reproduced as a continuous video reproduction signal in the figure (B). The signal is output from the switch 20 as shown.

When each head overlaps with a track of opposite azimuth, for example, tracks b, d, or track g+1, the level of the reproduced signal becomes minimum, and a discontinuity of the horizontal synchronizing signal, that is, a skew jump occurs.

The skew detection circuit 6 detects the minimum level of the reproduced signal (almost 0) or the discontinuity of the horizontal synchronization signal, and
The level of the detection signal is inverted as shown in Figure (C).

Since the CUE/REV signal is at H° during cue (and normal), the exclusive OR circuit 12 performs an exclusive OR between this H° and the detection signal level and outputs the result. That is, the logical output shown in FIG. 9(D) is the inverted level of the detection signal shown in FIG. 9(C).

Since the T-FF circuit 13 detects the rise of the input signal level and inverts its output level, its output signal is
As shown in Figure (E), it is reversed at the skew jump between c-+e and h→j.

If the detection signal and FF output signal are mistakenly inverted due to noise, etc., the operation of the subsequent parts will remain erroneous. It has become.

As shown in FIG. 9 and explained above, the signal waveforms of each part change, so if we look at the Y signal and the horizontal synchronization signal, the video signal recorded on each track is
0, the track aT cle is played back by the head 1A, and the track f+he J is played back by the head 1B.

The 0.5H phase shift of each Y signal and horizontal synchronization signal that occurs when heads IA and IB move between tracks, that is, a4Q, c→B, f-+h, h-+j, is the same as in the conventional example. Then, the Y/C mixing circuit 5 is activated by the switch 21 controlled by the detection signal shown in FIG. 9(C).
Composite signal output from through or 1/2H
It is delayed and becomes a continuous signal.

Regarding the C signal, it is necessary to further align the phase (reverse the phase correctly every 1H), and if this order is out of order, the colors will not be reproduced correctly, so the phase order will be out of order for a short time (within a few H). must be corrected.

As shown in FIGS. 6 and 7, between each track a+Q
, O→e, f→h, and h→j, the phase of the color signal advances by 0.58, respectively.

On the other hand, the detection signals shown in FIGS. 9(C) and (E).

Switch 21 and switches 22, 23, and 24, which are controlled by the FF output, respectively control the C signal through through during track a playback and 1/1 during track C playback.
0, 5H delay by 2H delay circuit 7, 1H delay by 1H delay circuit 10H during playback of tracks e and f, track h
During playback, the 1/2H delay circuit 7 and the 1H delay circuit 10H cause a 1.5H delay, and during playback of track j, there is a throughput.

Note that there is no problem since both the horizontal synchronizing signal and the C signal are continuous at e-+f, j→, where head switching is performed.

Therefore, the phase of the C signal is 0 due to track transition,
5H advance, switches 21 to 24 and delay circuit 7
．． The delay caused by IOH is canceled and continuity is maintained.

In the case of the triple speed review shown in Figure 10, the CUE/REV signal indicating the playback direction is L°, so the figure (D)
The logic output output from the exclusive OR circuit 12 shown in FIG.
) is the phase of the FF output of the T-FF circuit 13 shown in
This is different from the FF output shown in Figure (E).

Therefore, as shown in Figure 10 (B), as the track moves from e-40-+a, b-4z to x, the delay time changes from 0.1.5H, LH, 0,5H, 0 and vice versa. It is the same as the 5x speed queue except that it is set to .

As explained above, in this first embodiment, since the horizontal synchronization signal and the C signal are both continuous in phase, skew distortion and color disappearance on the monitor screen do not occur. This will be explained with reference to FIGS. 3 and 4.

FIGS. 3 and 4 are explanatory diagrams showing changes in the phase of the C signal in the case of 5x speed cue and 3x speed review, with time plotted on the horizontal axis.

FIG. 3(A) shows the position where a skew jump occurs in the reproduced video signal, and FIG. 3(B) and (C) show the positions where skew jumps occur in the reproduced video signal, and FIG. It shows the phase of the C signal.

In addition, the arrows between FIG. 3 (B) and (C) indicate the relationship in which each line in the upper row transitions to each line in the lower row due to delay, the solid line is the transition relationship before the skew jump, and the broken line is the transition relationship after the skew jump. It shows.

Similarly, FIGS. 4(A) to 4(C) and the arrows therebetween correspond to FIGS. 3(A) to (C) and the arrows, respectively.

In the case of a 5x speed cue, the delay of the C signal is 0.5 times as shown in FIG. 3(B) each time a skew jump occurs, according to the signal waveforms shown in FIGS. 9(C) and (E). 0.5H,
1H, 1, 5H, o in order, and the change in the phase of the final output C signal is as shown in the same figure (C), with a star marked at the bottom right of each line separated by the horizontal synchronization signal. 4 with
The phases of lines other than the main line are correctly inverted every 1H.

In the case of 3x speed review, the C signal is output by the delay circuit every time a skew jump occurs as shown in Fig. 4 (B) according to the signal waveforms shown in Figs. 10 (C) and (E). The delay is 0.1.5H, LH, 0.5H.

0 and the phase of the final output C signal is as shown in FIG.

The second embodiment shown in FIG. 2 has a 1H delay circuit 10H in the first embodiment (FIG. 1), but its high frequency characteristics are inferior, but the cost is low and the delay time is stable without being affected by temperature etc. This is an example in which the delay circuit 10L is replaced with a 1H delay circuit 10L made of, for example, a COD delay element, which is easy to use.

Therefore, one input terminal of the switch 23 on the input side receives the demodulated Y signal (from the FM modulated signal) from the Y signal processing circuit 3, and the other input terminal receives the Y signal (frequency-converted by the C signal processing circuit 4). The C signal in the low frequency range before
Enter each.

Therefore, the switch 22 switches the C signal in the low frequency range that is passed through or delayed by 1H, and outputs it to the C signal processing circuit 4.

Since the configuration other than the above is similar to that of the first embodiment, the explanation will be omitted.

Therefore, the signal waveforms of each part of this second embodiment are the same as the signal waveforms of the first embodiment (and the conventional example) shown in FIGS. 9 and 10, and the change in the phase of the C signal is also This is the same as that of the first embodiment shown in FIGS. 3 and 4 (B) and (C), respectively.

As explained above, according to the present invention, the 1H delay circuit, which is normally used for canceling H-correlated noise of the Y signal or for correcting dropout, is used during special playback of half-speed recording to output the C signal. Since the signal is switched to the C signal side only during the period during which 1H delay is required, one 1H delay circuit is used instead of the two 1H delay circuits 8 and 9 of the conventional example (Fig.
The H delay circuit 10H or IOL is sufficient, and the cost is significantly reduced.

During special playback, when the head tracking crosses the track on which the video signal is recorded and is played back, horizontal white bar noise appears on the monitor image near the crossing point where the head playback level drops, improving the monitor image quality. Even if the Y signal 1H delay circuit is activated, its effect is not very effective.
Except for the period when the delay circuit is used for the C signal (IV, ie, one field), it is effectively used for the Y signal (period of 1v) to improve image quality.

The special playback device for half-speed recording of a VTR according to the present invention has been described above, but the only difference between the PAL system and the SECAM system is the color signal transmission system.

Since the number of frames (25 frames/sec) and the number of scanning lines (625) are the same, the present invention can be applied to either system by simply changing the contents of the C signal processing circuit 4.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain the same effect as when using two expensive LH delay circuits instead of one, and it is possible to stabilize performance and reduce costs.

[Brief explanation of drawings]

1 and 2 are circuit diagrams showing the configurations of the first and second embodiments of the present invention; FIGS. 3 and 4 are explanatory diagrams showing changes in the phase of color signals during special reproduction; Figures 5 and 6 are schematic developed diagrams showing recording patterns of video signals on tape by standard recording and half-speed recording, respectively; Figure 7 is a partially enlarged view of the developed diagram shown in Figure 6; Figure 8 9 is a circuit diagram showing the configuration of a conventional example, and FIGS. 9 and 10 are waveform diagrams showing signals of various parts of the circuit. iA, iB... Head 6... Skew detection circuit (discontinuity detection means) 10H,
IOL...1H delay circuit 21...Switch (1/2H delay switching means) 22.2
5, 24...Switch (LH delay switching means) (E)F
F output j@9 Figure 10

Claims (1)

[Claims] 1. Two types of color signals are alternately transmitted for each horizontal scanning line,
Based on the television system in which one cycle of color signals is formed by signals for two consecutive horizontal scanning lines, each adjacent one is
Recording positions of horizontal synchronization signals that are continuous at a predetermined interval h on the video tracks when video tracks for recording video signals for fields are alternately recorded and reproduced by heads having mutually opposite azimuth angles and recorded at a standard speed. In a special playback device for a helical scan VTR, which is a helical scan VTR in which recording is performed such that the video tracks are aligned perpendicular to the direction of the video track, and which is also capable of playing back a tape recorded at a tape speed that is 1/2 of the standard speed. , a discontinuity detection means for detecting discontinuity in the reproduced video signal or its horizontal synchronization signal and outputting a detection signal; and in response to the detection signal output by the discontinuity detection means,
1/2H delay switching means for switching whether or not to delay the video signal by 1/2H; and a playback direction signal indicating whether the playback direction is forward or backward, and the detection signal, 1. 1H delay switching means for switching between delaying the luminance signal by 1H and delaying the color signal by 1H.