JPH05151704A - Video signal recording/reproducing device - Google Patents

Abstract

PURPOSE:To clamp a video signal to be regenerated and to regenerate a video signal having a high picture quality by preventing the superimposition of a pilot signal on a clamp signal when reproducing and eliminating the influence of the demodulated components of the pilot signal and its spurious. CONSTITUTION:At a TCI encoder 13, a luminance signal and a color difference signal are time-axially compressed and multiplexed, a TCI signal is formed and the clamp signal which becomes the reference base of the video signal is time-divisibly multiplexed. The supplying of the pilot signal from a pilot signal generator 21 to adders 24A and 24B is stopped by a switching circuit 23 based on a timing signal from a delay circuit 22 during the period of the clamp signal. The pilot signal is superimposed on the TCI signal by the adders 24A and 24B and a recording signal is formed. The recording signal is recorded on a magnetic tape 1 by magnetic heads 17A and 17B.

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 / reproducing apparatus, and more particularly to superimposing a pilot signal for tracking servo or clock reproduction on a video signal to record it on a recording medium.
The present invention relates to a video signal recording / reproducing apparatus which reproduces a recorded video signal by reproducing a pilot signal and performing tracking servo during reproduction.

[0002]

2. Description of the Related Art In a video signal recording / reproducing apparatus such as a video tape recorder (hereinafter referred to as VTR), a so-called drum servo or tape running speed for controlling the rotational speed and rotational phase of a head drum is used in order to perform accurate recording / reproducing. A so-called capstan servo that controls the traveling phase is used.

Specifically, for example, in the running phase control of a magnetic tape in a capstan servo during reproduction, a so-called control track which indicates a recording track position on a control track in the longitudinal (running) direction of the magnetic tape by a so-called control head at the time of recording. When a signal is recorded and played back, the recorded control track signal is played back, and the capstan motor is rotated in the capstan servo described above so that the phase of this control track signal matches the phase of the reference control signal. It is designed to control the phase. That is, so-called tracking servo is performed to control the magnetic head to scan the recording track correctly.

Incidentally, the tracking servo includes, for example, so-called ATF (Automatic Track Findin) in addition to the tracking servo using the controller track signal described above.
g) method is known. For example, a so-called 8 mm video tape recorder that uses a magnetic tape having a width of 8 mm as a recording medium employs a so-called helical scanning and azimuth recording method, and at the time of recording, four low-frequency pilot signals having different frequencies are used for tracking servo. (Pilot signals f ₁ , f ₂ , f ₃ , f ₄ below) are superposed (frequency division multiplexed) on the video signal so that the frequencies of adjacent tracks are different from each other and recorded. Therefore, the azimuth loss is small, the pilot signals are reproduced from the tracks on both sides of the track scanned by the magnetic head, and the tracking servo is applied so that the levels of these pilot signals become equal.

High-definition television (hereinafter referred to as high definition television) is currently under development, and part of it is in the stage of practical application. Further, development of an apparatus for recording / reproducing a high-definition video signal (hereinafter referred to as a high-definition video signal) while maintaining its high quality over a wide band is in progress. For example, the luminance signal Y and the color difference signal P _B, the high-definition video signal supplied as P _R, the luminance signal Y and the color difference signal P _B, the so-called TCI signal (Time Compressed Inte that time warp multiplexing P _R
A device (hereinafter referred to as a high-definition VTR) for performing recording / reproduction as a gration or a TDM signal is actively developed. And this HD VT
It is also considered to use the above-mentioned ATF method as the tracking servo for the R as well.

Now, the TCI signal will be briefly described. The TCI method is, for example, one horizontal scanning period (hereinafter 1
Luminance signal Y of line) and color difference signal P _B (B−
Y) and P _R (RY) are time-axis compressed and time division multiplexed on one line. Specifically, for example, since the color difference signals P _B and P _R have a narrower bandwidth than the luminance signal Y, they are not visually perceived as deterioration of image quality. After axial compression, the color difference signals P _B and P _R are time-compressed to 1/4 times, respectively, and then the color difference signals P _B and P _R are line-sequentially alternated for every other line and time-division multiplexed with the luminance signal Y. To do.

In the high-definition VTR, the high-definition video signals supplied as the luminance signal Y and the color difference signals P _B and P _R are time-axis compression-multiplexed as described above to be converted into a TCI signal, and the TCI signal is magnetic tape. Or a high-definition video signal recorded as a TCI signal on a magnetic tape is reproduced.

By the way, one field of a wideband signal such as a high-definition video signal is converted into the above-mentioned general VTR.
Similarly, if the recording is performed on one track, the diameter of the so-called head drum becomes several times, and it is difficult to realize a practical high-definition VTR. Therefore, the high-definition VTR, which is currently being developed, records the TCI signal for one field or one frame by dividing it into a plurality of tracks. As a method of division, there are so-called segment recording in which the rotation speed of the head drum is increased and so-called multi-channel recording in which a plurality of magnetic heads simultaneously perform recording, and both of them are used in the high-definition VTR.

Specifically, in a high-definition VTR, for example, the rotational speed of the head drum is set to be twice that of a general VTR, and the TCI signal is divided into two channels, A channel and B channel, according to the difference in color difference signals. The time axis is expanded so that one line of each TCI signal of these channels becomes two horizontal scanning periods, and a so-called horizontal synchronizing signal or the like is added. As a result, as shown in FIG.
The line portion is expanded in the time axis for two horizontal scanning periods (2H), and in the order from the beginning, a horizontal synchronization signal (SYNC) for pulling in horizontal synchronization, a so-called burst signal (BS), which segment signal is identified. A TCI signal in which the segment identification signal (SEG), the color difference signal C (P _B or P _R ) and the luminance signal Y are time division multiplexed is obtained.

Next, the TCI obtained as described above
For one frame of the signal, for example, the first field is set to segments # 1 and # 2, and the second field is set to segment #
The segments # 1 to # 4 are divided into four segments of 3 and # 4, and each of the segments # 1 to # 4 is divided into two channels of A channel and B channel according to the difference of the color difference signals as described above. Further, at this time, for example, the influence caused by dividing the TCI signal for one field into a plurality of tracks and recording is reduced, and the influence of so-called dropout of the magnetic tape is concentrated on one place on the reproduction screen. Therefore, the TCI signals in the channels of the segments # 1 to # 4 are every four lines, and the TCI signal of the first field is the A channel of the segment # 1, the B channel of the segment # 1, and the segment # 2. A channel of segment # 2, B channel of segment # 2, and the TCI signal of the second field is the A channel of segment # 3, the B channel of segment # 3, and the segment #
In the field, so-called shuffling is performed so that the A channel of 4 and the B channel of segment # 4 are in order.

The HDTV VTR has 18
A pair of magnetic heads A ₁ and A ₂ for the A channel arranged opposite to each other by 0 degrees, and a pair of magnetic heads B having a so-called azimuth different from them for the B channel arranged opposite to each other by 180 degrees. ₁ and B _2, and one frame of the shuffled TCI signal described above is transmitted to A of segment # 1.
The TCI signals of the channel and the B channel are respectively supplied to the magnetic heads A ₁ and B ₁ , and the TCI signals of the A channel and the B channel of the segment # 2 are respectively supplied to the magnetic heads A ₂ and B ₂ to the A channel of the segment # 3. B
Each TCI signal of the channel is sent to the magnetic head A ₁ ,
At B ₁ , the TCI signals of the A channel and B channel of the segment # 4 are simultaneously recorded by the magnetic heads A ₂ and B ₂ , respectively, so that the TCI signals are divided into 8 tracks for recording. At this time, a segment sync signal for synchronizing the segments at the beginning of each segment, a continuous waveform signal for reproducing the clock, a clamp signal that serves as a reference level for the video signal,
A ramp signal that serves as a reference for level correction is recorded.

Also, in this high-definition VTR, an audio signal, for example, a 4-channel analog audio signal is PCM.
The PCM audio signals are converted into audio signals, and these PCM audio signals are recorded on the same track by the same magnetic head as the video signals, with different areas.

As a result, as shown in FIG. 4, the TCI signal for one frame is recorded on the magnetic tape 70 by 2 channel (A channel, B channel) recording and 4 segment (SEG # 1 to # 4) recording. , Eight tracks 71
It is recorded by being divided into
An audio signal area 72 in which M audio signals and the like are recorded,
A video preamble area 73 in which a segment synchronization signal (V), a continuous waveform signal (CW), a clamp signal (L) and a ramp signal (R) are recorded, and a TCI signal (YR, YB).
Video signal area 74 is recorded.

Then, in this high-definition VTR, at the time of reproduction, the recorded segment synchronization signal is reproduced to bring in synchronization, the clock is reproduced based on the continuous waveform signal, and the video signal is generated based on these signals. Also, the audio signal is reproduced. At this time, the video signal is clamped based on the reproduced clamp signal, and the so-called peak-to-peak (Peak t peak) of the ramp signal is performed.
luminance signal Y based on the frequency obtained by dividing oPeak) into 256
And the levels of the color difference signals P _B and P _R.

[0015]

By the way, in a video signal recording / reproducing apparatus for performing time-division multiplexing of a clamp signal, which is a reference level of the video signal, on the video signal, as in the above-mentioned high-definition VTR, a tracking servo is used. When recording is performed by superimposing the pilot signal of, the level of the clamp signal may fluctuate because the component due to the demodulation of the pilot signal and its spurious is added to the reproduced clamp signal, and the clamp level may change. If it fluctuates, the above-mentioned frequency also changes, and the hue or the like in the reproduced image cannot be reproduced correctly.

The present invention has been made in view of the above circumstances, and, for example, as in a high definition VTR,
A clamp signal, which is the reference level of the video signal, is time-division multiplexed with the video signal and recorded, and the recorded video signal is
Based on the clamp signal to be reproduced, it is clamped and reproduced, and the pilot signal for tracking servo (capstan phase servo) is superposed (frequency division multiplexed) and recorded at the time of recording, and is reproduced at the time of reproducing. When the tracking servo is performed based on the video signal, it is possible to prevent the superimposed pilot signal from affecting the reproduced video signal and to reproduce a high quality video signal as compared with the conventional device. It is intended to provide a signal recording / reproducing device.

[0017]

According to the present invention, in order to solve the above problems, pilot signal generating means for generating a pilot signal for tracking and switch means for switching the pilot signal from the pilot signal generating means are provided. A multiplexing means for time-division-multiplexing a clamp signal serving as a reference level of the video signal on the video signal, and a pilot signal switched by the switch means on the output of the multiplexing means, and the video signal on which the pilot signal is superimposed A video signal recording / reproducing apparatus comprising: a recording unit for recording the data on a recording medium; and a control unit for controlling the switch unit so that the pilot signal is not superimposed on the clamp signal in the recording unit.

[0018]

In the video signal recording / reproducing apparatus according to the present invention, the video signal and the clamp signal serving as the reference level of the video signal are time-division multiplexed, and the pilot signal for tracking is superimposed on the time-division multiplexed signal. When recording,
The pilot signal is not recorded in the area where the clamp signal is recorded.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a video signal recording / reproducing apparatus according to the present invention will be described below with reference to the drawings. This embodiment is a high-definition television (so-called high-definition: High D
The video signal recorder / reproducer according to the present invention is applied to a video tape recorder (hereinafter referred to as a high-definition VTR) for efinition television, and FIG. 1 shows a circuit configuration of a recording system of the high-definition VTR.
FIG. 2 shows a circuit configuration of the reproduction system.

First, the high-definition VTR will be described. HDTV VTR is
A luminance signal Y and color difference signals P _B (BY) and P _R (RY) in a horizontal scanning period (hereinafter referred to as 1 line) are time-axis compressed and multiplexed (Time Compressed Integration) to obtain a so-called TCI signal. Recording in which a clamp signal or the like serving as a reference level of a signal is time-division multiplexed and a pilot signal for so-called capstan servo at the time of reproduction is superimposed and the obtained recording signal is recorded on the magnetic tape 1 by the recording heads 17A and 17B. As shown in FIG. 2 and the system, a pilot signal is detected from a reproduction signal (hereinafter referred to as an RF signal signal) reproduced from the magnetic tape 1 by the reproducing heads 41A and 41B, and the capstan servo in the capstan servo is detected based on the pilot signal. Phase control is performed, the TCI signal is reproduced from the RF signal, and the clamped TCI signal is clamped based on the clamp signal. From the luminance signal Y and the color difference signals P _B and P _R, and the time axis expansion is performed, and the obtained luminance signal Y and the color difference signals P _B and P _R are output.

The recording system, as shown in FIG. 1, is an analog / digital (hereinafter referred to as A / D) which converts the luminance signal Y and the color difference signals P _B and P _R into digital signals.
D) converters 12 _Y , 12 _B , 12 _R and the A / D
A TCI encoder 13 for forming a two-channel TCI signal by time-axis compression multiplexing the luminance signal Y and the color difference signals P _B , P converted into digital signals from the converters 12 _Y , 12 _B , 12 _R , and the TCI. A digital / analog (hereinafter referred to as D / A) converter 14 for converting the TCI signal of each channel from the encoder 13 into an analog signal.
A, 14B and an FM modulator 15 for performing a modulation suitable for recording, for example, an FM modulation on the TCI signal of each channel converted into an analog signal from the D / A converters 14A, 14B.
A and 15B, a pilot signal superimposing circuit 20 that superimposes a pilot signal on the modulation signals from the FM modulators 15A and 15B to form a recording signal for each channel, and a pilot signal superimposing circuit 20 for each channel from the pilot signal superimposing circuit 20. Recording amplifiers 16A and 16B for amplifying recording signals, respectively, and a recording head 1 for generating a modulation magnetic field based on recording signals of respective channels from the recording amplifiers 16A and 16B.
7A and 17B.

In this recording system, for example, the terminal 11
_The luminance signal Y supplied via each of _Y , 11 _B , and 11 _R is expanded by about 3/2 in the time axis, and the color difference signals P _B , P
_The color difference signals P _B and P _R obtained by time-compressing each _R by approximately ½ times are alternately line-sequential every other line, and the luminance signal Y of one odd line and the color difference signal of one odd line are set. P _B is time-division multiplexed within two horizontal scanning periods to form an A channel TCI signal, and the even-numbered line luminance signal Y and one even-line color difference signal P _R are time-divided within two horizontal scanning periods. It is designed to be multiplexed to form a B channel TCI signal. That is, the luminance signal Y and the color difference signal P
For example, _B and P _R are time-axis compressed to 3/4 times and 1/4 times, respectively, and the time-axis compressed color difference signals P _B and P _R are set to 1
The luminance signal Y and the luminance signal Y are time-division multiplexed alternately line by line and the obtained TCI signal is A
After dividing into T channel and B channel, performing the signal processing equivalent to making one line of the divided TCI signal into two horizontal scanning periods, and adding a synchronizing signal etc. to the TCI signal of each channel respectively, For example, FM modulation is performed on the FM modulated TCI signal, that is, so-called ATF (Automatic Track Finding).
A pilot signal for use is superimposed (frequency division multiplexed) to form a recording signal. This recording system uses so-called multi-channel recording for simultaneously recording one frame of the formed recording signal for each channel and so-called segment recording for dividing the TCI signal for one field into a plurality of tracks. The magnetic tape 1 is divided into a plurality of tracks for recording. For example,
The TCI signal for one frame is divided into eight tracks for recording by two-channel recording and four-segment recording.

[0023] Specifically, A / D converter 12 _Y is a luminance signal Y supplied through the terminal 11 _Y, for example, 44.
It is converted into a digital signal using a sampling clock of 55 MHz, and A / D converters 12 _B and 12 _R are connected to terminal 1
The color difference signals P _B and P _R supplied via 1 _B and 11 _R , respectively, are converted into digital signals using a sampling clock of 11.1375 MHz, for example. Then, the luminance signal Y and the color difference signals P _B and P _R converted into these digital signals are supplied to the TCI encoder 13.

The TCI encoder 13 is an A / D converter 1
The luminance signal _Y from 2 _Y is divided into two channels, for example, an odd line is an A channel and an even line is a B channel, and the time axis is extended to approximately 3/2 times. Further, the color difference signals P _B from the A / D converters 12 _B and 12 _R ,
P _R is divided into, for example, the color difference signal P _B of the odd line into the A channel and the color difference signal P _R of the even line into the B channel, and time-compressed by approximately 1/2.

The TCI encoder 13 temporarily stores the time-axis expanded luminance signal Y and the time-axis compressed color difference signals P _B and P _R, and then, for example, the odd-numbered line luminance signal Y and the odd-numbered line luminance signal Y. The line color difference signal P _B is time-division multiplexed for each line and is read out as an A channel TCI signal, and the even line luminance signal Y and the even line color difference signal P _R are time division multiplexed for each line to obtain the B channel. Is read out as the TCI signal. At this time, for example, the influence caused by recording the TCI signal for one field by dividing it into a plurality of tracks by the above-described multi-channel recording and segment recording is reduced, and so-called dropout of the magnetic tape 1 or the like is caused. So-called shuffling for changing the writing order and the reading order is performed in the field so that the influence is not concentrated on one place on the reproduction screen. And
A so-called horizontal sync signal is added to the shuffled TCI signal.
A burst signal, a segment identification signal for identifying a segment are time-division multiplexed for each line, and a segment synchronization signal for synchronizing the segment at the beginning of each segment, a continuous waveform signal for reproducing a clock, and a video A clamp signal serving as a reference level of a signal, a ramp signal serving as a level correction reference, and the like are time-division-multiplexed, and a TCI signal of each channel to which these synchronization signals and the like are added is supplied to D / A converters 14A and 14B. ..

The D / A converters 14A and 14B respectively convert the TCI signals of the respective channels to which the synchronizing signals and the like from the TCI encoder 13 are added into analog signals, and the TCI signals of the respective channels converted into these analog signals. The signals are supplied to the FM modulators 15A and 15B, respectively. As a result, in the FM modulators 15A and 15B, for example, as shown in FIG.
H), a horizontal synchronization signal (SYNC), a burst signal (BS), a segment identification signal (SEG),
A TCI signal in which the color difference signal C (P _B or P _R ) and the luminance signal Y are time division multiplexed is supplied.

The FM modulators 15A and 15B perform modulation suitable for recording, for example, emphasis or FM modulation on the TCI signal of each channel converted into the analog signal from the D / A converters 14A and 14B, respectively, and pilot signals. It is supplied to the superposition circuit 20.

As shown in FIG. 1, the pilot signal superimposing circuit 20 includes a pilot signal generator 21 for generating a pilot signal, a delay device 22 for delaying the timing signal from the TCI encoder 13, and the delay device. A switching circuit 23 for switching (turning on / off) the pilot signal from the pilot signal generator 21 based on the delayed timing signal from 22, and the pilot signal switched by the switching circuit 23 to the FM modulator. Adders 24A and 24B for superimposing the FM modulation signals of the respective channels from 15A and 15B, respectively.
Composed of and.

The pilot signal generator 21 has four different frequencies for capstan phase servo, that is, so-called tracking servo, and these frequencies are sufficiently lower than the frequency band of the video signal. Signals f ₁ , f ₂ , f ₃ , f ₄ ) are generated such that the frequencies are different between adjacent recording tracks, for example.

On the other hand, the delay device 22 includes the D / A converter 14
A has a delay time equivalent to the signal processing time in A and 14B and the FM modulators 15A and 15B, and shows the period of the timing signal supplied from the TCI encoder 13, for example, the clamp signal time-division multiplexed with the above-mentioned TCI signal. The timing signal is delayed by the delay time and supplied to the switching circuit 23.

Based on this timing signal, the switching circuit 23 operates from the pilot signal generator 21 to the adder 24A while the clamp signal is time-division multiplexed.
The supply of the pilot signal to 24B is stopped.

The adders 24A and 24B apply the pilot signal switched as described above to the FM modulator 15A and
The signals are superimposed on the FM modulation signals of the respective channels from 15B to form the recording signals of the respective channels. That is, the frequencies of the pilot signals f ₁ , f ₂ , f ₃ , and f ₄ are sufficiently lower than the frequency band of the video signal, and for example, during reproduction described later, recording tracks are reproduced by different reproduction heads having different so-called azimuths. The azimuth loss is small when reproduced, and the recording signal is a frequency-division multiplexed pilot signal and FM modulation signal. Then, the adders 24A and 24B supply the recording signals of the respective channels to the magnetic heads 17A and 17B via the recording amplifiers 16A and 16B, respectively.

The recording head 17A is, for example, a pair of magnetic heads 17 for the A channel which are arranged opposite to each other by 180 degrees.
The recording head 17B is composed of A ₁ and 17A _2.
Is composed of, for example, a pair of magnetic heads 17B ₁ and 17B ₂ for B channel, which have azimuth different from those of the magnetic heads 17A ₁ and 17A ₂ and are arranged 180 degrees opposite to each other.

By the way, the magnetic tape 1 is controlled by, for example, a so-called capstan speed servo so that its running speed advances by 8 tracks within a time required for recording a TCI signal for 1 frame. The running phase is controlled by a capstan phase servo (tracking servo) so as to be synchronized with a so-called PG (pulse generator) signal. The magnetic heads 17A ₁ and 17B ₁ or the magnetic heads 17A ₂ and 17B ₂ are recording amplifiers. 16
The recording signals of the respective channels from A and 16B are simultaneously recorded. Further, this HDTV has an audio system (not shown) for recording and reproducing audio signals, for example, converts 4-channel analog audio signals into so-called PCM audio signals, and converts these PCM audio signals into the recording head described above. 17A, 17
Depending on B, different areas are recorded on the same track. Further, the recorded PCM audio signal is reproduced by the reproducing heads 41A and 41B described later, and the audio signal is output.

Thus, the magnetic tape 1 has a TC for one frame as shown in FIG. 4 described in the prior art.
The I signal is divided into eight tracks 71 by two-channel (A-channel, B-channel) recording and four-segment (SEG # 1 to # 4) recording, and a PCM audio signal or the like is recorded on each track 71. A recorded audio signal area 72, a video preamble area 73 in which a segment synchronization signal (V), a continuous waveform signal (CW), a clamp signal (L) and a ramp signal (R) are recorded, and T
A video signal area 74 in which a CI signal is recorded is formed, and _{one of} pilot signals f ₁ , f ₂ , f ₃ , f ₄ is formed in an area other than the area in which the clamp signal (L) is recorded. The two adjacent tracks are recorded so as to have different frequencies and are superimposed.

Next, above as in the luminance signal Y and the color difference signal P _B, the high-definition video signal supplied as P _R, the luminance signal Y and the color difference signal P _B, TCI signal time-base compressed multiplexed to P _R A reproduction system of this high-definition VTR for reproducing a high-definition video signal from the magnetic tape 1 recorded as will be described.

As shown in FIG. 2, the reproducing system of the high-definition VTR has reproducing heads 41A and 41B for reproducing the RF signals of the A channel and the B channel from the magnetic tape 1, and the reproducing heads 41A and 41B. From the reproduction amplifiers 42A and 42B for amplifying the RF signals of the respective channels from the respective channels, and the RF signals of the respective channels from the reproduction amplifiers 42A and 42B are respectively subjected to FM demodulation to TC.
FM demodulators 43A and 43B for reproducing the I signal, and the FM
Clamp circuits 50A and 50B for converting the TCI signals of the respective channels supplied as analog signals from the demodulators 43A and 43B into digital signals and clamping the TCI signals based on the reproduced clamp signals.
And a TCI decoder 44 for reproducing the luminance signal Y and the color difference signals P _B and P _R from the TCI signal of each channel converted into the digital signal from the clamp circuits 50A and 50B.
And the D / A converters 45 _Y , 45 _B and 45 _R for converting the luminance signal Y and the color difference signals P _B and P _R reproduced by the TCI decoder 44 into analog signals and outputting them.

The reproducing system of the high-definition VTR reproduces the TCI signal of each channel by FM demodulating the RF signal of each channel reproduced from the magnetic tape 1 by the reproducing heads 41A and 41B, and the clamp signal from the RF signal. Is detected and the reproduced TCI signal is clamped based on this clamp signal, and then, as described above, the luminance signal Y and the color difference signal (P _B
Alternatively, the luminance signal Y and the color difference signals P _B and P _R are separated from the TCI signal in which P _R ) is time-axis compression-multiplexed, and the luminance signal Y is time-axis compressed approximately 2/3 times to obtain the color difference signal P _B. , P
_R is approximately doubled on the time axis to reproduce the luminance signal Y and the color difference signals P _B and P _R , and these luminance signal Y and color difference signal P are reproduced.
_B and P _R are output. In addition, at this time, the reproducing system detects a pilot signal from the RF signal and performs tracking servo based on the detected pilot signal.

Specifically, the reproducing head 41A is composed of, for example, a pair of magnetic heads 41A ₁ and 41A ₂ for the A channel which are arranged to face each other by 180 degrees.
The reproducing head 41B is, for example, the magnetic head 41.
A pair of magnetic heads 41B for B channel which have azimuth different from A ₁ and 41A ₂ and are arranged 180 degrees opposite to each other.
₁ and 41B ₂ .

The magnetic heads 41A ₁ and 41B
₁ simultaneously scans the track of segment # 1 or segment # 3 of the magnetic tape 1, and the magnetic head 4
1A ₂ and 41B ₂ simultaneously scan the tracks of segment # 2 or segment # 4, and the RF of each channel
The signals are reproduced, and these RF signals are reproduced by the reproduction amplifier 42A,
42B respectively.

By the way, this HDTV has a circuit (not shown) for performing capstan servo by the ATF system, like the 8 mm VTR described in the prior art,
This capstan servo circuit reproduces a pilot signal from an RF signal, that is, the azimuth loss is small because it is a low frequency, and the track scanned by the magnetic head, for example, the track on which the pilot signal f ₂ is recorded is located on both sides. pilot signals f _1, f ₃ is reproduced by also the so-called cross-talk from the track, these pilot signals f _1,
Tracking servo is applied so that the levels of f ₃ are equal, and the reproducing heads 41A and 41B are controlled so as to scan the recording track correctly. The reproducing heads 41A and 41B are the recording heads 17 of the recording system.
It can be shared with A and 17B.

The reproducing amplifiers 42A and 42B amplify the RF signals of the respective channels from the reproducing heads 41A and 41B and supply the amplified RF signals to the FM demodulators 43A and 43B. The FM demodulators 43A and 43B perform FM demodulation on the RF signals of the respective channels to obtain the TC of the respective channels.
The I signal is reproduced and these TCI signals are supplied to the clamp circuits 50A and 50B, respectively.

The clamp circuits 50A and 50B adopt, for example, a so-called feedback clamp system, and as shown in FIG. 2 described above (note that since these have the same circuit configuration, a capital letter indicating a channel is used). The description will be made with the alphabets omitted.) The clamped TCI signal is converted into a digital signal, and the TCI decoder 44
To the A / D converter 52, an error detection circuit 53 that detects the level of the clamp signal from the output of the A / D converter 52, and detects an error of the clamp signal with respect to a predetermined reference level; A D / A converter 54 for converting the error from the detection circuit 53 into an analog signal and an error from the D / A converter 54 are subtracted from the TCI signal from the FM demodulator 43 to clamp the TCI signal. And the clamped TCI signal is supplied to the A / D converter 52.

The A / D converter 52 converts the TCI signal supplied as an analog signal clamped from the FM demodulator 43 via the adder 51 into a digital signal, and the TCI signal converted into this digital signal. Signal to TC
It is supplied to the I decoder 44 and the error detection circuit 53. The error detection circuit 53 is composed of, for example, a sample hold circuit and the like, and samples and holds a clamp signal obtained by reproducing the clamp signal recorded in the video preamble area at the time of recording and also holds this sample and hold with respect to a predetermined reference level. An error in the level of the clamp signal thus detected is detected, and the detected error is supplied to the adder 51 via the D / A converter 54. The adder 51 subtracts the error converted into the analog signal by the D / A converter 54 from the TCI signal from the FM demodulator 43, clamps the TCI signal, and A / D-converts the clamped TCI signal. It is supplied to the TCI decoder 44 via the device 52.

By the way, at the time of recording, since the pilot signal is not recorded in the area where the clamp signal of the recording track is recorded, the error detection circuit 53 described above is used.
Can detect the level of the clamp signal on which the pilot signal is not superimposed. That is, the level of the clamp signal can be detected more accurately than in the conventional device that superimposes and records the pilot signal on the clamp signal as well, and is not affected by the demodulation component of the pilot signal or its spurious. , TCI signals can be clamped.

The TCI decoder 44 performs signal processing such as so-called time base correction, deshuffling, and the like.
The luminance signal Y and the color difference signals P _B and P _R are separated from the CI signal, the separated luminance signals Y are compressed on the time axis, and the color difference signals P _B and P _R are expanded on the time axis, for example, at the time of recording. Because it is line-sequential alternately every other line,
The color difference signal P _B of the even line which is not directly reproduced from the magnetic tape 1 is formed by the interpolation process of obtaining the average value of two adjacent color difference signals P _B of the odd line which is reproduced, and the color difference signal P _B of the odd line which is not reproduced is also formed. Color difference signal P _R
It is formed by interpolation processing for obtaining the average value of two adjacent color difference signals P _R of the even-numbered lines to be reproduced. Further, at this time, the TCI decoder 44 determines the levels of the luminance signal Y and the color difference signals P _B and P _R based on the frequency obtained by dividing the so-called peak to peak of the reproduced ramp signal into 256. decide. That is, this high-definition VTR can correctly clamp the TCI signal as described above, and can improve the reproducibility of hue or the like in the reproduced image as compared with the conventional device. Then, the TCI decoder 44 supplies the luminance signal Y and the color difference signals P _B and P _R thus obtained to the D / A converters 45 _Y , 45 _B and 45 _R for each signal.

The D / A converters 45 _Y , 45 _B and 45 _R are
Luminance signal Y and the color difference signal P _B, P _R respectively converted into analog signals, the luminance signal and converts these analog signals Y and the color difference signal P _B, P _R each terminal 46 _Y, 4
It is output to, for example, a monitor receiver via 6 _B and 46 _R. That is, a high-definition video signal is reproduced from the TCI signal recorded on the magnetic tape 1 in a state where one frame is divided into eight tracks by multi-channel recording and segment recording, and this is reproduced on the monitor receiver. An image based on the high definition video signal is displayed.

In this monitor receiver, since the recording is carried out without superimposing the pilot signal on the clamp signal at the time of recording, at the time of reproduction, the level of the clamp signal is changed to that of the pilot signal. The image can be accurately detected without being affected, and an image with good reproducibility can be displayed.

[0049]

As is apparent from the above description, according to the present invention, the video signal and the clamp signal which is the reference level of the video signal are time-division multiplexed, and the time-division multiplexed signal is used for the tracking pilot signal. When a signal is superimposed and recorded, the reproduced video signal is affected by the demodulation component of the pilot signal and its spurious by preventing the pilot signal from being recorded in the area where the clamp signal is recorded. Can be accurately clamped without. That is, it is possible to reproduce a video signal having good reproducibility such as hue.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of a recording system of a high-definition VTR to which a video signal recording / reproducing device according to the present invention is applied.

FIG. 2 is a block diagram showing a circuit configuration of a reproduction system of the high definition VTR.

FIG. 3 is a diagram showing a format of a TCI signal.

FIG. 4 is a diagram showing a tape format of a magnetic tape used in a high-definition VTR.

[Explanation of symbols]

 13 ... TCI encoder 20 ... Pilot signal superposition circuit 21 ... Pilot signal generator 23 ... Switching circuit 24A, 24B ... Adder

Claims (1)

[Claims] 1. A pilot signal generating means for generating a tracking pilot signal, a switch means for switching the pilot signal from the pilot signal generating means, and a clamp signal which is a reference level of the video signal and is time-divided into the video signal. Multiplexing means for multiplexing, recording means for superimposing a pilot signal switched by the switch means on an output of the multiplexing means, and recording a video signal on which the pilot signal is superimposed on a recording medium, and a clamp signal in the recording means. And a control means for controlling the switch means so that a pilot signal is not superimposed on the video signal recording / reproducing apparatus.