JPH0564139A - Video signal recorder - Google Patents

Abstract

PURPOSE:To eliminate crosstalk from an adjacent track without remarkable deterioration in the vertical resolution when a different signal is recorded between adjacent tracks in a multi-channel VTR. CONSTITUTION:A couple of 2-channel heads being two magnetic heads arranged close to each other are fitted on a drum. A TDM signal resulting from applying time division multiplexing to a luminance signal and a color difference signal from the four magnetic heads in total is given to a shuffling circuit 5, in which the signal is shuffled and the result is frequency-modulated by frequency modulation. circuits 11A, 11B. Analog signal processing circuits 10A, 10B specify the initial phase of a carrier of a frequency modulation signal. This is used to invert crosstalk from an adjacent track for each 1H after de-shuffling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal recording device applicable to, for example, a multi-channel VTR, and more particularly to a device for suppressing crosstalk between tracks.

[0002]

2. Description of the Related Art In an analog VTR, an oblique track is formed on a magnetic tape by a magnetic head without interposing a guard band in order to improve recording density. Therefore, during reproduction in which the magnetic head scans tracks, unwanted crosstalk from adjacent tracks becomes a problem. Conventionally, in order to suppress this crosstalk, the carrier frequency of the FM modulated signal is shifted by fh / 2 (fh is a horizontal frequency) between adjacent tracks.

In this way, as shown by the solid line in FIG. 16, the spectrum of the reproduced signal (main signal) from the desired track is distributed for each fh. On the other hand, the spectrum of crosstalk from adjacent tracks is distributed for each fh as shown by the broken line in FIG. 16, but when the horizontal correlation is strong between the tracks, there is a difference between the spectrum of the main line signal and fh / 2. Therefore, the carrier frequency of crosstalk is fh /
2 + nfh (n is an integer). Since there is a frequency interleave relationship in this way, crosstalk can be reduced by passing the reproduced signal through a comb filter.

When recording a signal having a large amount of information such as an HDTV signal, a multi-channel VTR in which a plurality of tracks are simultaneously formed by one scanning is used. As one of them, a time division multiplexed (abbreviated as TDM) signal including a time axis expanded luminance signal and a time axis compressed color signal is FM-modulated and recorded on a magnetic tape as, for example, 2 channels (2 tracks). It The color signal is the color difference signal PR
And PB line sequential signals. After this TDM signal is shuffled, it is recorded on a magnetic tape as shown in FIG. In FIG. 17, X indicates the feeding direction of the magnetic tape, and Y indicates the scanning direction of the magnetic head.

In FIG. 17, two magnetic heads having different gap extension directions of the head elements are provided close to each other on the rotating drum, and the two magnetic heads are 180 °.
2 is a track pattern when two sets of heads are arranged at an opposing interval of. The two magnetic heads simultaneously form A and B channel tracks on the magnetic tape.
These two tracks are called a segment. The video signal of one field is recorded in two segments and four tracks. Shuffling is a 4H TD that is continuous in time.
This is a process of distributing the M signal to four tracks (2 segments). That is, as shown in FIG. 17, the 1H signal 1R (R means that the color difference signal PR is included) is recorded on the A track of the first segment, and the 2H signal 2 is recorded.
B is recorded on the B track of the first segment, the 3H signal 3R is recorded on the A track of the first segment, and the 4H signal 4B is recorded on the B track of the second segment. Hereinafter, this process is repeated.

The shuffling is not limited to that shown in FIG. 17, but may be performed as shown in FIG. That is, the 1H signal 1R is recorded on the A track of the first segment, the 2H signal 2B is recorded on the A track of the second segment, and the 3H signal 3R is recorded on the B track of the first segment, The 4H signal 4B is recorded on the B track of the second segment.

[0007]

As described above, in a multi-channel VTR and a device for shuffling, the color difference signal PR (or P
If B) is recorded, the adjacent tracks are
The color difference signal PB (or PR) is recorded. Since the signals recorded on these adjacent tracks have different average DC levels, the conventional 1/2 fh shift cannot be applied. Therefore, an object of the present invention is to provide a video signal recording apparatus capable of reducing crosstalk without significantly deteriorating vertical resolution even when different FM modulated signals are recorded between adjacent tracks. It is in.

[0008]

According to the present invention, there is provided a video signal recording apparatus adapted to record a video signal on a magnetic tape (42) by a rotary head (H1A, H1B, H2A, H2B). A shuffling circuit (5) for rearranging the array, and a circuit (11A, for FM-modulating the output video signal of the shuffling circuit (5).
11B) and a circuit (10A, 10B) that is coupled to the FM modulation circuit (11A, 11B) and controls the initial phase for each 1H (H: horizontal period) of the carrier of the FM modulation video signal. (10A, 10B) is characterized in that the initial phase of the FM modulation signal is defined so that the crosstalk from the adjacent track is inverted every 1H after the deshuffling performed on the reproducing side. It is a video signal recording device.

[0009]

[Operation] 1H after the crosstalk is disshuffled
Since the initial phase of the carrier of the FM modulated signal is defined so as to be inverted every time, crosstalk can be reduced without causing a significant deterioration in vertical resolution.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of a recording system according to an embodiment, in which a luminance signal Y and color difference signals PR and PB are supplied to input terminals 1R, 1B and 1Y, respectively. These components are, for example, high-definition signal components. The signals are converted into digital signals by the A / D converters 2R, 2B and 2Y. The digital color difference signals PR and PB are supplied to the line-sequentializing circuit 3, and the color difference signal P is supplied every 1H.
A line-sequential color signal in which R and PB are alternately located is generated.
The digital luminance signal and the digital line-sequential color signal are T
It is supplied to the DM encoder 4.

The TDM encoder 4 expands the luminance signal on the time axis and compresses the line-sequential color signal on the time axis to obtain the TDM signal.
Form a signal. This TDM signal is the shuffling circuit 5
Is supplied to. The shuffling circuit 5 performs a shuffling process, and generates two-channel TDM signals recorded on the A track and the B track, respectively. The signal of each channel from the shuffling circuit 5 is supplied to the adder circuits 7A and 7B. Adder circuit 7A,
A composite sync signal including a sync signal and a burst signal is supplied to the terminal 7B from the terminal 8.

The output signal of the adder circuit 7A is the D / A converter 9
It is supplied to A and converted into an analog signal. This analog signal is supplied to the analog signal processing circuit 10A. The analog signal processing circuit 10A includes a pre-emphasis circuit and an initial phase defining circuit described later. The output signal of the analog signal processing circuit 10A is supplied to the FM modulation circuit 11A. FM modulation circuit 11A to switching circuit 12A
The FM modulation signal is supplied to the input terminal V of the same, and the FM modulation signal is fed back to the analog signal processing circuit 10A for controlling the initial phase.

The D / A converter 9B, the analog signal processing circuit 10B, the FM modulation circuit 11B, and the switching circuit 12B are also connected to the adder circuit 7B for the B track, as in the case of the A track. The switching circuits 12A and 12B are provided to record PCM audio signals, and the PCM audio signals from the audio signal processing circuit 13 are supplied to their input terminals A, respectively. The PCM audio signal is recorded in an audio signal recording section provided at an end of each track on the head entry side. The stereo PCM signal from the input terminals 14L and 14R and the sub data from the input terminal 14S are input to the audio signal processing circuit 13. The sub data includes an ID signal or the like that represents the characteristics of the audio signal. The audio signal processing circuit 13 performs processing such as coding of error correction code and synchronization block coding.

The output signals of the switching circuits 12A and 12B are supplied to the recording amplifiers 15A and 15B, respectively.
The output terminal 16A of the recording amplifier 15A and the recording amplifier 15
A signal recorded on the A track and the B track is generated at the B output terminal 16B. The recording signal of the A track is distributed by a switching circuit (not shown) to the two magnetic heads forming the A track (opposed at 180 °), and similarly, the recording signal of the B track has two magnetic heads. Will be distributed to. Then, the data is recorded on the magnetic tape wound around the peripheral surface of the rotating drum.

FIG. 2 shows the structure of the reproducing system of this embodiment. 21A and 21B are supplied with respective reproduction signals of the A track and the B track. The reproduction signal of the A track is supplied to the FM demodulation circuit 23A and the audio signal processing circuit 24 via the reproduction amplifier 22A. The reproduction signal of the B track is transmitted to the FM demodulation circuit 2 via the reproduction amplifier 22B.
3B and audio signal processing circuit 24.
The audio signal processing circuit 24 performs processing such as error correction and error correction of the reproduced signal, outputs a stereo PCM signal to the output terminals 25L and 25R, and outputs sub data to the output terminal 25S.

The demodulation output from the FM demodulation circuit 23A is supplied to the de-emphasis circuit 26A. After the output signal of the de-emphasis circuit 26A is converted into a digital signal by the A / D converter 27A, the de-shuffling circuit 2
8 are supplied. The deshuffling circuit 28 performs a process reverse to that of the shuffling circuit 5 of the recording system and restores the time series of the TDM signal to the original one.

The TDM signal from the deshuffling circuit 28 is supplied to the TDM decoder 29. The TDM decoder 29 decodes the TDM signal and outputs a luminance signal and a line-sequential color signal. The luminance signal is converted into an analog signal by the D / A converter 33Y and taken out to the output terminal 34Y. The line-sequential color difference signal is output by the separation circuit 30.
The color difference signals PR and PB are separated, and the comb filter 31
It is supplied to R and 31B respectively. Comb filter 31
Crosstalk between adjacent tracks is reduced by R and 31B as described later. Comb filter 31R, 3
1B is basically configured to add a signal that has passed through a 1H delay circuit and a signal that does not pass through this. The comb filters 31R and 31B are not limited to such a basic configuration, and other circuits for reducing this crosstalk by utilizing the phase inversion of the crosstalk every 1H. Can be adopted. Further, crosstalk may be reduced by a non-linear vertical de-emphasis circuit.

The output signals of the comb filters 31R and 31B, that is, the demodulated line-sequential color signals are interpolated by the interpolation circuit 32.
And the color difference signal in the horizontal section which does not exist is interpolated by the signals before and after that. The output signal of the interpolation circuit 32 is D
The color difference signals PR and PB supplied to the A / A converters 33R and 33B and converted into analog signals are output terminals 34.
R and 34B are taken out respectively.

FIG. 3 shows an example of a rotary head device used in this recording system. The A-track head H1A having the first azimuth angle and the B-track head H1B having the second azimuth angle different from the first azimuth angle are located close to each other on the rotary drum 41 in the rotation axis direction. It is attached by being shifted by one track. Similarly, an A-track head H2A having a first azimuth angle and a B-track head H2B having a second azimuth angle are mounted at rotational angle positions different from those of the heads H1A and H1B by 180 °.

The magnetic tape 42 is 180 ° + α
Of the rotary heads H1A, H1B, H2A, H2.
B is rotated at a rotation speed of 60 Hz. Therefore, in one field period of the video signal, 2 segments (4 tracks)
Is formed. As an example, the diameter of the drum 41 is, for example, 62 mm, and the tape speed is 34.97 mm /
s and the track pitch are, for example, 15.11 μm.

The rotary heads H1A and H1B are mounted on the magnetic tape 41 by the rotary head device having the above-described structure.
Alternately, the rotary heads H2A and H2B alternately form four tracks in one field in each tape contact section corresponding to a rotation angle of 180 °, and a high-definition signal is recorded. That is, in one rotation of the first half, in which the rotary heads H1A and H1B come into contact with the tape 42, in the first 180 ° rotation section, two tracks are simultaneously formed by the rotary heads H1A and H1B. Two tracks are simultaneously formed by the rotary heads H2A and H2B in the latter half 180 ° rotation section where H2B comes into contact with the tape 42.

Two tracks simultaneously formed by two rotary heads H1A, H1B or H2A, H2B make up one segment, and a video signal for ½ field and one associated with this video signal are formed in this one segment. The PCM audio signals for the / 2 field period are stored in separate recording areas. An HDTV video signal and an audio signal for one frame are recorded in four segments.

The TDM encoder 5 of the recording system shown in FIG. 1 time-division-multiplexes a luminance signal, a line-sequential signal of color difference signals, and other additional signals in 1H.
A signal is generated. This TDM signal is shown in FIG. 4, and includes a luminance signal Y, a color signal C, a synchronization signal SYNC, a burst signal SB and the like.

In the analog signal processing circuit 10A of the recording system, the initial phase of the FM modulated signal as shown in FIG. 5 is defined, and the crosstalk from the adjacent track after FM demodulation during reproduction is reduced by the comb filters 31R and 31B. A phase control circuit is provided to enable this. Here, the initial phase is the phase of the carrier of the FM modulated signal for each 1H, and for example, the phase of the carrier immediately before or after the horizontal synchronizing signal is controlled. The output signal of the pre-emphasis circuit 51 is supplied to the subtraction circuit 52, and the output signal of the subtraction circuit 52 is supplied to the FM modulation circuit 11A. The subtraction circuit 52 subtracts the correction voltage from the DC component of the input TDM signal, and thereby the initial phase of the FM modulation signal is controlled to a predetermined value.

The FM modulation signal from the FM modulation circuit 11A is supplied to the phase comparison circuit 53 and the timing generation circuit 54.
The phase difference from the reference phase signal from is detected. This phase difference is supplied to the low pass filter 55, and a correction voltage is generated from the low pass filter 55. Timing generation circuit 5
As will be described later, 4 generates a reference phase signal such that the initial phase of the carrier is inverted every 1H on one of the adjacent tracks and is constant on the other track. With the phase control circuit shown in FIG.
The initial phase of the carrier of the FM-modulated signal to be recorded can be defined as desired every 1H.

Hereinafter, it will be described in more detail that crosstalk in the reproduced signal can be suppressed by controlling the initial phase. FIG. 6 shows a part of the track pattern of this embodiment. As in FIG. 17, this is to record a video signal of one field as four tracks (two segments) on a magnetic tape. In FIG. 6, B represents a 1H signal including the color difference signal PB, and R represents the color difference signal P.
1H signal including R is shown. L attached to each signal,
m and n represent field numbers, Rm + i or Bm +
j represents 1H including the i-th or j-th color difference signal PR or PB of the m-th field. Furthermore, θ
Represents the initial phase of the FM modulated signal of each H.

In the track pattern of FIG. 6, when the signals Rm + 1, Bm + 2, Rm + 3 and Bm + 4 are focused as an example, the main signal and the crosstalk after FM demodulation are shown in FIG. Will be things. However, assuming that R and B each have a horizontal correlation, the FM angular frequency is ω R,
Expressed as ωB. Further, in FIG. 7, the upper track and the lower track mean the positional relationship shown in FIG. As shown in FIG. 7, the frequency difference (ωR −ωB
) As well as the phase difference (θR-θB) occurs during FM demodulated crosstalk.

Deshuffling is performed by the deshuffling circuit 28 shown in FIG.
The separation circuit 30 causes the separation circuit 30 to generate R and B signals as shown in FIG. In each of R and B, the crosstalk in the signal that is temporally continuous is 1H.
If the phase is inverted every time, the comb filters 31R, 31
B can reduce this crosstalk. That is, as can be seen from FIG. 7, when the main signal is R, the following equation 1 shows the condition for reducing crosstalk. In Equation 1, the upper equation shows the condition for reducing the crosstalk from the lower track, and the lower equation shows the condition for reducing the crosstalk from the upper track. Further, ± means + or −.

[0029]

[Equation 1]

Similarly, when the main signal is B, the following equation 2
Shows the conditions for reducing crosstalk.
In Equation 1, the upper equation shows the condition for reducing the crosstalk from the lower track, and the lower equation shows the condition for reducing the crosstalk from the upper track.

[0031]

[Equation 2]

By rearranging the above equations 1 and 2, the following equation 3 showing the condition for reducing the crosstalk can be obtained. The initial phase control circuit for the FM modulated signal shown in FIG. 5 realizes the equation 3. Further, FIG. 9 shows the result of controlling the initial phase of the FM-modulated carrier according to the equation (3). In the example of FIG. 9, the initial phase of the R signal is inverted every 1H, and the constant phase (0) is set for the B signal. Since the initial phase is controlled after the shuffling, as the processing at the time of recording, the initial phase of track 1 is 0, that of track 2 is 0, that of track 3 is π, that of track 4 is 0.
Is controlled.

[0033]

[Equation 3]

FIG. 10 shows another example of controlling the initial phase of the carrier of the FM modulated signal so as to reduce the crosstalk. The initial phase of track 1 on which the signal of the m-th field is recorded is 0, that of track 2 is 1 / 2π, that of track 3 is 3 / 2π, and that of track 4 is π. The initial phase of each of tracks 1, 2, 3 and 4 on which the signal of the next n-th field is recorded is π,
It is controlled as 1 / 2π, 3 / 2π, 0. The control of the initial phase is repeated with these eight tracks as a cycle.

FIG. 11 shows still another example of controlling the initial phase of the carrier. The initial phase of track 1 in which the signal of the m-th field is recorded is 0, and that of track 2 is 1
/ 2π, that of track 3 is controlled to 1 / 2π, and that of track 4 is controlled to 0. The initial phase of each of the tracks 1, 2, 3 and 4 in which the signal of the next n-th field is recorded is controlled to be π, 3 / 2π, 3 / 2π, π. The control of the initial phase is repeated with these eight tracks as a cycle.

FIG. 12 shows still another example of the control of the initial phase of the carrier. Also in FIG. 12, control is performed with a cycle of 8 tracks. That is, regarding the eight tracks of the m-th field and the next n-th field, the initial phase is (0, 3/2) in order from the track 1.
π, 3 / 2π, 0, π, 1 / 2π, 1 / 2π, π). Although not shown, there is a method of controlling the initial phase other than the above example.

As described above, according to the present invention, the crosstalk is reduced by the comb filters 31R and 31B after performing the FM demodulation and the deshuffling. Like the present invention, although the initial phase of the FM modulated signal is defined, like the conventional 1/2 fh shift,
By providing a comb filter before FM demodulation,
It is possible to reduce crosstalk. However, as can be understood from the track patterns of FIG. 6, FIG. 17, or FIG. 18, since the processing is performed before deshuffling, the signal R or B synthesized by the comb filter has a time difference of 4H. Will be things. As a result, the vertical resolution of the main line signal passed through the comb filter deteriorates. The present invention can prevent such deterioration of vertical resolution.

In the above example, the video signal of one field is recorded on four tracks. When recording a 1-field video signal on 8 tracks, the initial phase may be controlled as described above. A process for reducing crosstalk when recording a 1-field video signal on 6 tracks will be described below. Similar to FIG. 6, the FM modulated signals R and B recorded on each track and their initial phases are shown in FIG. Video signals of the m-th field are recorded on tracks 1 to 6 in FIG. In the case of the track pattern shown in FIG. 13, the condition of the initial phase that can reduce the crosstalk is expressed by the following Expression 4.

[0039]

[Equation 4]

FIG. 14 shows that the video signal of one field is 6
A specific example of the control of the initial phase in the case of recording on one track will be shown. Tracks 1, 3 and 5 on which the video signal of the m-th field is recorded have a constant initial phase (0), and tracks 2 and 6 thereof have an initial phase of (π,
0, π, 0, ...) and 1H, and the track 4 is switched (0, π, 0, ...) and 1H. Regarding the six tracks on which the video signal of the next nth field is recorded, it is assumed that the control of the initial phase of the mth field is shifted by 1H in the track extension direction. Hereinafter, the control of this initial phase is repeated.

FIG. 15 shows that the video signal of one field is 6
Another example of the control of the initial phase when recorded on one track is shown. The initial phase of each track is controlled with a cycle of 12 tracks on which the video signals of the mth and nth fields are recorded. That is, (0, 4/3
π, 1 / 3π, 2 / 3π, 2 / 3π, 0, π, 2/3
The initial phase of each track is controlled in the order of π, 2 / 3π, -2 / 3π, 1 / 3π, 0). In addition to these FIG. 14 and FIG. 15, there are methods for controlling the initial phase.

The present invention is based on the VTR of the above embodiment.
However, the present invention can be applied to a video signal recording apparatus in which signals between adjacent tracks are different as a result of shuffling performed when recording a video signal on multiple tracks.

[0043]

According to the present invention, by defining the initial phase of the carrier of the FM modulated signal at the time of recording, the crosstalk is inverted every 1H after the processing of FM demodulation and deshuffling at the time of reproduction. It can be something. Therefore, this crosstalk can be reduced by a comb filter or the like, and deterioration of the vertical resolution can be prevented as compared with the case where crosstalk is removed by using the FM modulation signal in the shuffled state.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration for recording according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a structure for reproduction according to an embodiment of the present invention.

FIG. 3 is a schematic diagram for explaining a head arrangement of an embodiment.

FIG. 4 is a waveform diagram of an example of a TDM signal.

FIG. 5 is a block diagram of a circuit for controlling the initial phase of the FM modulated signal.

FIG. 6 is a schematic diagram showing a track pattern for explaining control of an initial phase of an FM modulation signal when a video signal of one field is recorded on four tracks.

FIG. 7 is a schematic diagram showing crosstalk components.

FIG. 8 is a schematic diagram showing a time series of a deshuffled signal for explaining the control of the initial phase of the FM modulation signal.

FIG. 9 is a schematic diagram showing an example of control of an initial phase of an FM modulation signal when a video signal of one field is recorded on four tracks.

FIG. 10 is a schematic diagram showing another example of the control of the initial phase of the FM modulation signal when the video signal of one field is recorded on four tracks.

FIG. 11 is a schematic diagram showing still another example of the control of the initial phase of the FM modulation signal when the video signal of one field is recorded on four tracks.

FIG. 12 is a schematic diagram showing still another example of the control of the initial phase of the FM modulation signal when the video signal of one field is recorded on four tracks.

FIG. 13 is a schematic diagram showing a track pattern for explaining control of an initial phase of an FM modulation signal when a video signal of 1 field is recorded on 6 tracks.

FIG. 14 is a schematic diagram showing an example of control of an initial phase of an FM modulation signal when a video signal of 1 field is recorded on 6 tracks.

FIG. 15 is a schematic diagram showing another example of the control of the initial phase of the FM modulation signal when the video signal of one field is recorded on six tracks.

FIG. 16 is a frequency spectrum diagram used for explaining a conventional crosstalk reduction method.

FIG. 17 is a schematic diagram showing an example of a track pattern of a conventional multi-channel VTR to which the present invention can be applied.

FIG. 18 is a schematic diagram of another example of a track pattern of a conventional multi-channel VTR to which the present invention can be applied.

[Explanation of symbols]

 5 Shuffling circuit 11A, 11B FM modulation circuit 28 Deshuffling circuit 31R, 31B Comb filter

Claims (1)

[Claims] 1. A video signal recording apparatus for recording a video signal on a magnetic tape by a rotary head, comprising: shuffling means for rearranging the arrangement of the video signal; and an output video signal of the shuffling means. Of the carrier of the FM-modulated video signal, and means for controlling the initial phase for each 1H (H: horizontal period) of the carrier of the FM-modulated video signal. 1 crosstalk from adjacent tracks after the deshuffling done
A video signal recording apparatus, wherein an initial phase of the FM modulated signal is defined so as to be inverted every H.