JPH0628437B2 - Video signal recorder - Google Patents

Description

The present invention relates to a video signal recording device suitable for a MUSE signal.

[Outline of Invention]

The present invention relates to a video signal recording apparatus for converting a video signal of the MUSE system into a low carrier FM signal, frequency-multiplexing it with a pilot signal, and recording it on a medium, in a positive and negative sync peak level and pedestal of an original video signal. By switching the frequency of the pilot signal in accordance with the level, it is possible to record the original composite synchronizing signal, easily obtain the original synchronizing signal at the time of reproduction, and reduce the jitter of the video signal.

[Conventional technology]

Recently, MUSE (Multiple Sub-Nyquist-Sampling) that transmits high-definition television (HDTV) signals on one channel of satellite broadcasting
Encoding) system was announced and corresponding transmitters, receivers, video discs, VTRs, etc. were also developed. In the MUSE method, the required transmission bandwidth of the HDTV signal is compressed to 1/4 by sub-Nyquist sampling that makes a cycle of four fields, and the HDTV signal is transmitted at a bandwidth of 8.1 MHz. As shown in FIG. 5, the MUSE signal of the base band has a luminance signal Y and a time-compressed line-sequential color signal C which are time-division multiplexed, and has a positive sync signal. This positive sync signal is a positive and negative sync signal of the original HDTV signal as shown in FIG.
It is formed by folding back the negative polarity portion.

The known MUSE video disc is an optical recording of the above MUSE signal in the form of a low carrier FM signal on the disc.

The carrier frequency of this FM signal is selected as follows, for example.

Black level S _B = 12 MHz White level S _W = 16 MHz [Problems to be solved by the invention] By the way, in a normal optical video disc reproducing apparatus, it is possible to prevent jitter (variation in the time axis direction) of a reproduced video signal. Therefore, a jitter servo for controlling the position of the optical pickup in the track direction is applied to the optical pickup by using the horizontal synchronizing signal and the color burst signal in the video signal to absorb the fluctuation of the rotation phase of the video disc.

However, as shown in FIG. 5, since the MUSE signal is in positive polarity synchronization, the synchronization signal cannot be easily separated by the conventional amplitude separation method. Therefore, the pilot signal is multiplexed with the FM signal and recorded on the disk, and the disk rotation speed, jitter control, etc. are performed using this pilot signal. The frequency of the pilot signal is selected to be, for example, 2.278 MHz (= 135 _H / 2) so as to have an interleaved relationship with the horizontal synchronizing frequency in order to avoid beat interference with the video signal.

However, in the conventional MUSE video disc, there is a problem that the bipolar sync signal of the original HDTV signal cannot be easily obtained from the playback sync signal.

In view of such a point, an object of the present invention is to provide a video signal recording apparatus capable of easily obtaining an original synchronization signal during reproduction and reducing the jitter of the video signal.

[Means for solving problems]

The present invention converts a video signal having a positive composite sync signal formed on the basis of an original composite sync signal of both positive and negative polarities into an FM signal having a low carrier frequency and records the FM signal on the medium MD.
In a video signal recording apparatus for recording a pilot signal of a predetermined frequency on an FM signal by multiplexing, a phase-locked oscillator (31), frequency downconverters (32) to (34), and a multiplier (35). A pilot signal generating circuit (30) for generating a first pilot signal having a predetermined frequency and second and third pilot signals having a predetermined frequency relationship, and first to third pilot signals of the pilot signal generating circuit Provided with a selection control circuit (40) for selectively deriving, while supplying the horizontal synchronization signal of the original composite synchronization signal to the phase-locked oscillator,
The original composite sync signal is supplied to the selection control circuit to select the first to third pilot signals corresponding to the original composite sync signal pedestal level and the positive and negative sync peak levels, respectively, and to multiplex the FM signal. It is a video signal recording device for recording.

[Action]

With this configuration, the original composite sync signal can be recorded, and the original sync signal can be easily obtained during reproduction.
The jitter of the video signal is reduced.

〔Example〕

An embodiment in which the video signal recording device according to the present invention is applied to an optical video disc will be described below with reference to FIGS.

The configuration of one embodiment of the present invention is shown in FIG.

In FIG. 1, (10) shows an optical system as a whole, and light from an argon laser (11) of a recording light source is intermittently supplied in an optical modulator (12), and a recording lens system (13) allows a glass master MD to be recorded. The light is focused on the photosensitive material (photoresist) Ph applied on.

Light from the helium / neon laser (14) enters the lens system (13) through the dichroic mirror (15). The reflected light from the glass master MD is guided to the light receiver (16) by the dichroic mirror (15). The output of the focus servo circuit (17), which changes according to the output of the light receiver (16), is the lens system.
It is supplied to (13) and the focus servo is performed. The position information of the lens system (13) is supplied to the microcomputer (18), and the motor MM is controlled so as to rotate at a constant linear velocity.

(20) shows the signal system as a whole, and the HDTV system VTR (1)
The composite color video signal from is supplied to the MUSE encoder (2) and the input terminal (20s) in common, and the above-mentioned MUSE signal is supplied from the encoder (2) to the input terminal (20v).

The MUSE signal is supplied to the FM modulator (22) via the buffer (21), and the output of the FM modulator (22) is supplied to the optical modulator (12) via the mixer (23). It The sync signal separated in the sync separation circuit (24) connected to the input terminal (20s) is supplied to the sync signal generation circuit (25). Reference numeral (30) is a pilot signal generating circuit, and as shown in FIG. 2, a phase locked oscillator (PLL) (31) and frequency down converters (32) to (34).
And a multiplier (35). This pilot signal generating circuit (30) is based on the horizontal synchronizing signal from the synchronizing signal generating circuit (25) and has a first frequency of p = 135 _H / 2.
Is supplied to the mixer (23) via the first changeover switch S ₁ and the second and third pilot signals of frequencies u and l are supplied to the second changeover switch S ₂
Supply to each fixed contact of. The movable contact of the switch S ₂ is connected to the other fixed contact of the switch S ₁ .

(40) is a timing signal generation circuit, which is composed of comparators (41) to (43) as shown in FIG. 2, and is a timing signal from the synchronization signal generation circuit (25) based on the HDTV composite synchronization signal. Is generated, which causes the switches S ₁ and S _{2 to} be switch-controlled.

Next, the operation of the embodiment of the present invention will be described with reference to FIG.

In FIG. 2, the horizontal synchronizing signal is supplied from the synchronizing signal generating circuit (25), and the output of the PLL (31) is a continuous wave of a frequency of 8p = 540 _H locked (phase synchronized) with the horizontal synchronizing signal. Become. The output of this PLL (31) is a 1/8 down converter (3
2) and the 1/12 downconverter (33) are commonly supplied, and the output of the downconverter (33) is supplied to the 1/4 downconverter (34) and the pedestal from the downconverter (32). A first pilot signal with a frequency p = 135 _H / 2 corresponding to the level is obtained.

(35) is a multiplier as a balanced modulator,
Of p = 135 _H / 2 and the output of the downconverter 34 at frequency of Δ = 45 _H / 4. The output of the multiplier (35) has a center frequency of u = p + Δ, respectively.
And l = p-Δ bandpass filters (36) and (37) are commonly supplied to the second bandpass filters (36) and (37) at frequencies u and l corresponding to positive and negative sync peak levels, respectively. And a third pilot signal is obtained.

In the embodiment of FIG. 1, the changeover switch S ₁ is in the connection state opposite to that shown in the figure during the pedestal level period of the composite synchronizing signal (see FIG. 6) by the timing signal which will be described in detail later, and the remaining period. Are controlled so that they are in the connection state shown in the figure. Further, the changeover switch S ₂ is in the connection state shown during the positive polarity synchronizing pulse period (see FIG. 6),
During the negative polarity sync pulse period, control is performed so that the connection state is the opposite of that shown in the figure.

As a result, as shown in FIG. 3, the MUSE signal is recorded as an FM signal on the glass master MD, and the MUSE signal is frequency-multiplexed with this FM signal to obtain positive and negative sync peak levels of the original HDTV signal and U, l and p of the pilot signal generating circuit (30) are respectively associated with the pedestal levels.
The pilot signal of the frequency is recorded in a so-called ternary frequency shift keying (FSK) signal format.

The audio signal is converted into PCM and multiplexed during the vertical blanking period of the MUSE signal.

In order to switch the pilot signal as described above, in this embodiment, the timing signal is formed as follows.

In FIG. 2, in the comparators (window comparators) (41), (42) and (43) of the timing signal generating circuit (40),
The composite sync signal of the HDTV signal is commonly supplied from the sync signal generation circuit (25).

Three kinds of reference voltages Ep, which are equal to the pedestal level and the positive and negative sync peak levels of the composite sync signal, respectively.
Eu and El are the first, second and third comparators (41), (42)
And (43) respectively.

As a result, the output of the first comparator (41) becomes "Hi" during the pedestal level period. Further, the output of the second comparator (42) becomes "Hi" during the positive polarity synchronous peak level period. Similarly, the output of the third comparator (43) becomes "Hi" during the negative sync peak level period.

The pair of NAND gates (51) and (52) and the OR gate (53) constitute the first changeover switch S ₁ (see FIG. 1), and similarly, the pair of NAND gates (55) and (56). And the OR gate (57), the second changeover switch S ₂ (first
(See the figure) is configured. The timing signal from the first comparator (41) is supplied to the NAND gate (51) and also to the NAND gate (52) via the inverter (54).
The timing signal from the second comparator (42) is a NAND gate
In addition to being supplied to (55), the timing signal from the third comparator (43) is supplied to the NAND gate (56). As a result, at the desired timing as described above, the 1/8 downconverter (32) of the pilot signal generation circuit (30) and the bandpass filter (36), (3
The outputs of 7) are respectively supplied to the mixer (23).

A reproducing apparatus corresponding to one embodiment of the present invention is constructed as shown in FIG.

In FIG. 4, a duplicate disc D is rotated at a constant linear velocity by a motor M, and an optical pickup PU is arranged facing the disc D. Although not shown, this pickup PU has a focus and tracking servo mechanism. The playback output of the pickup PU is the playback amplifier
High-pass filter (62) and bandpass filter (63) via (61)
To the FM demodulator (64), and the demodulated output is supplied to the MUSE decoder (65). The pilot signal from the bandpass filter (63) is supplied to the PLL (66). This PLL (66) is configured to include a voltage controlled crystal oscillator (VCXO) and a low-pass filter having an appropriate time constant. The input signal and the oscillation output of the VCXO are phase-compared, and the comparison output is a jitter servo circuit. (67)
And the pickup PU is servo-controlled.

(68) is a ternary FSK demodulator, which is a bandpass filter (63)
The pilot signals of frequencies p, u, and l respectively corresponding to the pedestal level and the positive and negative sync peak levels of the original HDTV sync signal are supplied from the demodulator (68), and the demodulation output of the demodulator (68) is the original composite sync signal of both positive and negative polarities. Becomes This demodulation output
It is supplied to the MUSE decoder (65) and is replaced with the positive sync signal of the MUSE signal.

In this embodiment, since the FM signal based on the MUSE signal and the ternary FSK signal based on the original composite sync signal are frequency-multiplexed and recorded, the original composite sync signal can be easily obtained during reproduction, and Jitter is reduced.

The embodiments in which the present invention is applied to an optical video disc have been described above, but the present invention can be applied to video discs of other systems and also to a video tape recorder.

〔The invention's effect〕

As described above in detail, according to the present invention, the frequency of the pilot signal is switched according to the positive / negative sync peak level and the pedestal level of the original video signal, so that the original composite sync signal can be recorded. As a result, it is possible to obtain a video signal recording device that can easily obtain the original synchronization signal during reproduction and reduce the jitter of the video signal.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a video signal recording apparatus according to the present invention, FIG. 2 is a block diagram showing a configuration of a main part of an embodiment of the present invention, and FIG. FIG. 4 is a spectrum diagram showing the frequency arrangement of the embodiment, FIG. 4 is a block diagram showing the configuration of the reproducing apparatus corresponding to the embodiment of the present invention,
6 and 6 are waveform diagrams for explaining the present invention. (10) is an optical system, (22) is an FM modulator, (25) is a synchronizing signal generating circuit, (30) is a pilot signal generating circuit, (31) is a phase locked oscillator (PLL), and (40) is timing. Signal generation circuit, MD
Is a master disc.

Claims (1)

[Claims] 1. A video signal having a positive composite sync signal formed on the basis of a positive / negative bipolar original composite sync signal is converted into an FM signal having a low carrier frequency and recorded on a medium, and a pilot having a predetermined frequency is used. A video signal recording apparatus adapted to record a signal by multiplexing it on the FM signal, including a phase-locked oscillator, a frequency downconverter and a multiplier, and a first pilot signal of the predetermined frequency and a predetermined frequency relationship. And a selection control circuit for selectively deriving the first to third pilot signals of the pilot signal generation circuit. The horizontal sync signal of the original composite sync signal is supplied to the phase-locked oscillator, and the original composite sync signal is supplied to the selection control circuit to generate the original composite sync signal pedestal. A video signal recording apparatus characterized in that the first to third pilot signals are selected in correspondence with the digital level and the positive and negative sync peak levels, respectively, and are multiplexed and recorded on the FM signal.