JPS61189795A - Recording information signal converting device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a beat trouble at a demodulating video signal and to record plural information signals at the same track by changing over and using either of a trap circuit and a comb-line filter in accordance with the S/N of a composite color video signal to be recorded and removing a luminance signal. CONSTITUTION:A delaying composite color video signal removed from a delaying line 7 for correction is supplied to a trap circuit 9, a signal component is stopped in the vicinity of a color sub-transporting wave number 3.58MHz and the luminance signal is fetched. A switch 10, when the S/N of the input composite color video signal of an input terminal 1 is smaller than the constant value, selects and outputs the input luminance signal of a contact 10a, and when the S/N is larger than the constant value, selects the input luminance signal of a contact 10b. On the other hand, a transporting chrominance component fetched from an adder circuit 6 is frequency- converted so that the color sub-carrier frequency is about 2.56MHz as much as the 5/7-fold frequency at a low area converting circuit 11, goes to be the low area converting transporting chrominance components and the band is shared and multiplexed at the high frequency band of the luminance signal selected and outputted from the switch 10 at the adder circuit 12.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a recording information signal converting device, which converts an information signal to be recorded, particularly a color video signal, into a band-limited luminance signal and a high frequency band of the luminance signal. The present invention relates to a converting device that converts the signal into a band-sharing multiplexed low-pass conversion carrier color signal and outputs the signal to be recorded on a recording medium.

2. Prior Art Conventionally, as one of the video discs, the applicant of the present invention has previously published Japanese Patent Application Laid-Open No. 52-123205 (Japanese Patent Application No. 51-3880).
A capacitance I change detection and reading type video disc without a needle guide groove, which was proposed in No. 9), is known. In such a video disk, the main information signal is recorded in a spiral or concentric track as a change in geometric shape, and approximately in the middle between two adjacent tracks, a main information signal is recorded every rotation period of the disk. One of the first and second tracking control reference signals is recorded while being switched alternately.

When reproducing such a video disc, an error signal obtained by reproducing the first and second tracking control reference signals recorded on both sides of the main information signal recording track and comparing their envelope detection levels is used. Since the playback stylus (sensor) can be tracked and controlled, no stylus guide groove for tracking is formed on the disc, thereby extending the life of the playback stylus and disc, and suitably realizing special playback and random access. It has the feature of being able to

The main information signal of the video disc mentioned above is band-sharing multiplexed into a band-limited luminance signal and a high frequency band of this luminance signal, as previously disclosed by the present applicant in Japanese Patent Publication No. 58-23998. A low-pass conversion carrier chrominance signal and a frequency modulated signal of an audio signal band located in a frequency band higher than the upper limit frequency of the band-limited luminance signal, or a plurality of signals having different frequency bands from each other. It is a composite signal consisting of frequency modulated waves, and is recorded in the form of a frequency modulated wave signal obtained by collectively frequency modulating a predetermined negative carrier wave with this composite signal. According to the information signal recording method proposed by the present applicant, even if the distortion in the transmission system is relatively large, since it is a single carrier, multiple information signals can be recorded so as not to cause beat disturbance in the demodulated video signal. It can record on the same track, does not cause any cross-modulation distortion that may occur with duty cycle modulation, and has other features.

Problem to be Solved by the Invention In the processing process for converting a composite color video signal into the above-mentioned composite signal, the band-sharing multiplexing portion of the luminance signal with the low-frequency conversion carrier chrominance signal has a frequency interleaving relationship. In order to make full use of the P-wave, a comb-shaped filter is used in principle.

Further, the carrier color signal is also converted into a P wave from the composite color video signal by a comb-shaped filter, and then converted into a low frequency signal. Therefore,
Due to the frequency characteristics of the comb-shaped filter, the vertical resolution of the luminance signal is slightly reduced.

On the other hand, in the NTSC system composite color video signal, 2
Since the luminance signal component above MHz is usually relatively small, and the non-frequency interleaved luminance signal component that occurs when the video information is moving is also usually small, the trap circuit removes most of the carrier color signal in the composite color video signal. Even if the luminance signal is extracted at the same time, it has been confirmed that there is almost no visual difference in the reproduced image compared to when the luminance signal is separated into P waves using a comb-shaped filter.

Therefore, when converting an NTSC composite color video signal to a video signal for recording, it is not necessary to perform P-wave processing on the band-sharing multiplexed portion of the low-frequency conversion carrier color signal of the luminance signal using a comb-shaped filter for the luminance signal. It can be said that there is no.

However, when considering the noise mixed into the carrier color signal that has been low-pass converted, this noise has a color subcarrier frequency of 3.58M.
Since the noise in the carrier color signal of H7 is added to the noise in the band where the luminance signal is band-shared multiplexed after this carrier color signal is converted to a low frequency band and band-shared multiplexed,
It is clear that when the luminance signal is extracted using a trap circuit, the noise in the low-pass conversion carrier chrominance signal becomes larger than when the luminance signal is converted into a P wave using a comb filter. Signal-to-noise ratio of input composite color video signal (
If S/N> is bad, extracting the luminance signal with a trap circuit poses a problem in that the reproduced carrier color signal deteriorates to S/N.

Therefore, the present invention extracts the luminance signal by selectively using either the trap circuit or the comb filter depending on the S/ of the composite color video signal to be recorded. Recorded information signal conversion that solves both the problems of vertical resolution deterioration due to a type filter and S/N deterioration of reproduced carrier color signals in the luminance signal separation method using a trap circuit when the composite color video signal has poor S/N ratio. The purpose is to provide equipment.

Means for Solving the Problems The recording information signal converting device according to the present invention converts a carrier color signal P that includes at least a bandpass filter and a delay circuit.
A comb-shaped filter for waves, a trap circuit that blocks the passage of frequency components near the color subcarrier frequency in the composite color video signal, and an output signal of the comb-shaped filter and the delayed composite color video signal are added together. an adder circuit for extracting a luminance signal given a predetermined frequency characteristic; a switch for selectively outputting one of the output signals of the trap circuit and the adder circuit according to the signal-to-noise ratio of the composite color video signal; and the comb-shaped filter. It consists of a circuit that converts the output carrier chrominance signal to a low frequency band and then performs band sharing multiplexing on the high frequency band of the luminance signal from the switch.

The above-mentioned predetermined frequency characteristic is a flat characteristic in the low frequency band, and at least fH/2 in the above-mentioned low-frequency conversion carrier color signal band.
(However, fH is the horizontal scanning frequency) It exhibits a comb-shaped filter characteristic in which the pass band is an even multiple of the frequency and the attenuation band is an odd multiple of fH-+/2, and the level of the attenuation band changes as the frequency increases. This is a frequency characteristic that approaches the level of the passband as it becomes lower.

Operation The above switch adjusts the signal-to-noise ratio (S) of the composite color video signal.
When /to> is larger than a certain value (when S/to is good), the output luminance signal of the trap circuit is selectively output. As a result, when a luminance signal is converted into a P wave from a composite color video signal using a conventional comb-shaped filter that has comb-shaped filter characteristics with a constant and small level of attenuation band (deeper valley depth) in the required band, No vertical resolution degradation occurs.

On the other hand, when the S/total value of the composite color video signal is smaller than the above-mentioned constant value (when the S/total value is bad), the above switch is activated.
The output luminance signal of the adder circuit is selectively output. As a result, compared to the deterioration of the reproduced carrier color signal to S/ that occurs when a signal is recorded and reproduced by extracting the luminance signal using a trap circuit and band-sharing multiplexing it to the low-pass conversion carrier color signal, the reproduction Deterioration of the carrier color signal to S/ can be reduced. Moreover, in this case, the luminance signal is given a comb-shaped filter characteristic in which the level of the attenuation band approaches the level of the pass band as the frequency becomes lower within the predetermined band.
The deterioration of vertical resolution is reduced compared to the case of using a conventional comb-shaped filter for luminance signals whose attenuation band level is constant and small.

Regarding the effect of reducing the deterioration of the reproduced carrier color signal to S/, there is almost no difference compared to the case where a conventional comb-shaped filter for luminance signals is used. This is shown by the solid line X in Figure 9.
Even if the level of the attenuation region in the frequency characteristic of the conventional comb-shaped filter for luminance signals shown by is smaller than the level of the attenuation region in the frequency characteristic at the output end of the adder circuit shown by the broken line XI in the figure, Noise energy is not reduced by the level of this attenuation range, but by increasing the area of the triangle shown with hatching in the figure. This is thought to be because the area in the present invention, which has hatching on the lower left in the figure, does not decrease much even if the level of the attenuation range is about half that of the conventional one with hatching. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail below with reference to the drawings and embodiments.

Embodiment FIG. 1 shows a block system diagram of an embodiment of the apparatus of the present invention. In the figure, the NTS to be recorded that has entered input terminal 1
The C-scheme composite color video signal is supplied to a 1H delay circuit 2 and delayed by one horizontal scanning period (one day), and is then supplied to a bandpass filter 3.

The bandpass filter 3 is, for example, a Bessel bandpass filter with a circuit configuration as shown in Figure @2, and its passband is 3.57.
9545M) (Z±800kl-IZ. In Fig. 2, from input terminal 23 to output terminal 2
4 has a resistor R+, a coil L+, and a capacitor C+.

C2 and coil L3 are connected in series in this order, and the connection point between capacitors CI and C2 is grounded via a parallel circuit of capacitor C3 and coil L2, and the connection point between output terminal 24 and coil L3 is connected to resistor R2. is grounded through. Here, the resistance values of the resistors R+ and R2 are each 470Ω, the coil L1 is 15.4 μH, and the coil L2 is 9.5 μH.
81μH, L3 100.4μH, capacitor C+ 1
29+)F, C2 at 197pF, C3 at 2001)F
The amplitude-frequency characteristics of this bandpass filter when selected respectively are as shown by the solid line in FIG. 3, and the band b! J, 2.5568178Ml-IZ
(Frequency 5/7 times the color printing carrier frequency) ±500k
At HZ, the level increases as the frequency increases,
And the color subcarrier frequency is 3.579545 M f-1
The characteristics are selected to allow the z carrier color signal to pass through without attenuation. Also, the group delay time characteristic of this bandpass filter is 3.579545 M, as shown by the broken line ■ in Figure 3.
It becomes flat at Hz±800k)-1z.

A signal extracted from the bandpass filter 3 having such a configuration and characteristics is supplied to an adder circuit 6 shown in FIG. Also I
The composite color video signal extracted after being delayed by 1H in the entire band by the Hil delay circuit 2 has the same configuration as the bandpass filter 3,
After the high frequency components of the carrier chrominance signal and the luminance signal are converted into P waves by the bandpass filter 4 having the same frequency characteristics, the inverting amplifier 5
, where the phase is shifted by 180°, and
After being amplified, it is supplied to the adder circuit 6. This results in
The adder circuit 6 subtracts the high frequency components of the carrier chrominance signal and the luminance signal that have been P-waved by the bandpass filter 3 and a signal obtained by extending this signal by 1HN (adding the signal obtained by inverting and amplifying the signal extended by IH1). .

Therefore, the above 1H delay circuit 2. Bandpass filter 3°4,
The inverting amplifier 5 and the adding circuit 6 constitute a carrier color signal P-wave phase comb filter, and its frequency characteristic is fH/2 in a frequency band of approximately 1 μH2 or more, as shown in FIG.
It exhibits a comb-shaped filter characteristic in which the pass band is an odd multiple of fH/2 and the attenuation band is an even multiple of fH/2, and the envelope connecting the peak levels of the pass band is as shown by the broken line ■. , exhibiting characteristics that match the amplitude-frequency characteristics shown in FIG. 3 of the bandpass filters 3 and 4.

Further, the output delayed composite color video signal of the 1-to-1 delay circuit 2 is delayed by the delay amount of the bandpass filter 3 by the correction delay line 7, and then supplied to the adder circuit 8, where the carrier extracted from the adder circuit 6 is Added to color signal. As is well known,
In the case of the NTSC system, the color subcarrier frequency fSC of the carrier color signal is 455/2 times the horizontal scanning frequency [H, so the phase differs by 180° between the beginning and end of 1H (the beginning of the next 1H). Therefore, due to the addition of the adder circuit 8, the carrier color signal in the delayed composite color video signal from the correction delay line 7 is canceled out by the output carrier color signal of the adder circuit 6, and only the luminance signal is extracted. It will be done.

That is, the frequency characteristics at the output end of the adder circuit 8 are as follows:
As shown in Fig. 5, it exhibits a flat pass characteristic in the low frequency band below about IMH7, and in the high frequency band above about 1 MHz, the attenuation range is an odd multiple of fH/2.
It has a comb-shaped filter characteristic whose passband is an even multiple of fH/2, and the envelope ■ that connects the dip levels of its attenuation range has the opposite characteristics to the envelope ■ shown in Figure 3, and its passband The envelope V connecting the peak levels of is flat. Therefore, from the adder circuit 8, the level of the attenuation range of the comb-shaped filter characteristic changes to the level of the passband as the frequency becomes lower, at least in the band of the low-frequency conversion carrier color signal (approximately 2.56 MHz ± 500 kHz > described below). A luminance signal imparted with approaching frequency characteristics is extracted.

The output luminance signal of this adder circuit 8 has a frequency shown in FIG. As can be seen from the characteristics, this high frequency luminance signal component is not completely removed and is included to a large extent. As a result, the level of the attenuation region is larger (the valley is shallower) than when using a conventional complete comb filter for luminance signals.
Therefore, it can be said that the degradation in vertical resolution is less in this embodiment.

Returning to FIG. 1 again, the delayed composite color video signal taken out from the correction delay line 7 is also supplied to a trap circuit 9 having the frequency characteristics shown in FIG. 6, where the color subcarrier number is The carrier color signal components at and around 3.58 MHz are blocked from passing, and the luminance signal is extracted. The output luminance signal of the adder circuit 8 is sent to the contact 10 of the switch 10.
The output luminance signal of the trap circuit 10 is supplied to the contact 10b of the switch 10. This switch 10
selects and outputs the input luminance signal of the contact 10a when the S/N of the input composite color video signal of the input terminal 1 is smaller than a certain value, and selects and outputs the input luminance signal of the contact 10b when the S/N is larger than the above certain value. It can be switched manually or automatically to selectively output the luminance signal. When switching the switch 1o manually, for example, a person looks at a monitor image of the input composite color video signal and determines whether the S/N is good or not, and then switches the switch 1o. On the other hand,
When switching the switch 10 automatically, for example, the level of a specific section within the vertical blanking period of the input composite color video signal is detected, and the detected level is higher than the original value (the blanking level when there is no noise). is also greater than a certain value.

On the other hand, the carrier color signal taken out from the adder circuit 6 is supplied to the low frequency conversion circuit 11, where it is frequency converted so that its color subcarrier frequency is approximately 2.56 MH7 which is 5z7 times the frequency. This becomes a gamut-transformed carrier color signal. The adder circuit 12 performs band sharing multiplexing of this low-pass converted carrier chrominance signal onto the high frequency band of the luminance signal selectively output from the switch 10, and passes this multiplexed signal through a low-pass filter with a cutoff frequency of 3.1 MHz and a sixth filter. It consists of a trap circuit having frequency characteristics as shown in the figure and a group delay characteristic compensation circuit from the trap circuit, and is supplied to a low-pass filter/trap circuit 13 having an overall frequency characteristic as shown in FIG. A multiplexed signal consisting of a band-limited luminance signal and a low-pass converted carrier chrominance signal whose luminance signal level in the band of a frequency modulated audio signal (FM audio signal) to be described later is sufficiently attenuated by the low-pass filter trap circuit 13 is , pre-emphasized by the pre-emphasis circuit 14 and then supplied to the adder circuit 20.

On the other hand, the first. The second channel audio signal is incoming and supplied to a frequency modulator 17.18;
Frequency modulation is performed on carrier waves of 3.43 MHz and 3.73 MHz. 3 taken out from the frequency modulator 17゛,
The first FM audio signal in the band of 43MHz±75kHz7 and the 3,73M)-1 extracted from the frequency modulator 18.
The second FM audio signals in the band 2±75k)-1z are each frequency-division multiplexed in an adder circuit 19 and then supplied to an adder circuit 20. As a result, the adder circuit 20
A composite signal consisting of the band-sharing multiplexed signal from the pre-emphasis circuit 14 and the frequency division multiplexed signal from the adder circuit 19 is output. FIG. 8 shows the frequency positional relationship of each signal of this composite signal. In the figure, ■ indicates a luminance signal, ■ indicates a low frequency conversion carrier color signal, and ■ and ■ indicate the above-mentioned first and second FM audio signals, respectively.

This composite signal is supplied to a frequency modulator 21, where it is frequency-modulated all at once and then output to an output terminal 22.

When the frequency-modulated composite signal output from the output terminal 22 is recorded on the above-mentioned video disc, the signal to be inserted as an index signal is inserted into the switching connection portion of the first and second tracking control reference signals. After being frequency division multiplexed into a low frequency band, the light is supplied to a first optical modulator. On the other hand, the first and second tracking control reference signals have a lower frequency than the frequency band of the multiplexed signal supplied to the first optical modulator, have different repetition frequencies, and have a burst shape. A signal that is alternately switched every rotation period of the recording master and synthesized in time series is supplied to the second optical modulator.

1st. The first and second modulated laser beams extracted from the second optical modulator are applied to the photosensitizer on the disc-shaped recording master by 1/2.
They are focused at a distance of about a track pitch.

Furthermore, the exposed recording master disk is subjected to a known development process and a disk making process, respectively, to produce a large number of copies of information recording disks that have an electrode function and have no needle guide grooves.

Note that the present invention is not limited to the above embodiments; for example, the input signal of the trap circuit 9 may be a composite color video signal that does not pass through the 11-1 delay circuit 2, and the input signal of the trap circuit 9 may be a composite color video signal that does not pass through the 11-1 delay circuit 2. The order may be changed.

Although not directly related to the present invention, the input signals to the input terminals 15 and 16 may be signals in the audio signal band, computer program signals or other signals, and the recording medium may be a magnetic disk, magnetic tape, etc. But that's fine.

Effects of the Invention As described above, according to the present invention, the S
Since the luminance signal from the trap circuit is recorded when /N is good, it is possible to prevent the vertical resolution from deteriorating which would occur when recording and reproducing the luminance signal separated by the P wave using the comb filter. The S/N deterioration of the reproduced carrier color signal can be made to a level that does not cause visual problems.On the other hand, when the S/N of the composite color video signal is poor, the reproduced carrier color that occurs when a trap circuit is used for the luminance signal P wave can be reduced. The S/N deterioration of the signal can be improved to almost the same S/N as the S/N of the reproduced carrier color signal when the luminance signal is separated into P waves using a conventional comb-shaped filter and recorded and reproduced.
Furthermore, compared to conventional comb-shaped filters for luminance signals, the level of the attenuation band of the comb-shaped filter approaches the level of the passband as the frequency decreases, so it has many advantages such as reducing the deterioration of vertical resolution. It has the following.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the device of the present invention;
2 is a circuit diagram showing an embodiment of the bandpass filter in the block system shown in FIG. 1, and FIG. 3 is an amplitude diagram of the circuit shown in FIG. 2.
A diagram showing an example of frequency characteristics and group delay time characteristics. Figures 4 to 7 are diagrams each showing frequency characteristics of each part in the block system shown in Figure 1. Figure 8 is a diagram showing an example of the block system shown in Figure 1. FIG. 9 is a diagram illustrating the magnitude of noise energy removed by the comb-shaped filter characteristics. 1...NTSC system composite color video signal input terminal, 2
... 1HN extension circuit, 3, 4... bandpass filter, 5.
...Inverting amplifier, 6.8,12.19.20...Addition circuit, 9...Trap circuit, 10-...Switch, 1
1...Low-pass conversion circuit, 13...Low-pass filter/trap circuit, 15.16...Audio signal input terminal.

Claims (1)

[Claims] Of the luminance signal and carrier chrominance signal separated from the composite color video signal, the luminance signal is band-limited, the carrier chrominance signal is low-band converted to the high frequency band of the band-limited luminance signal, and these two signals are band-sharing multiplexed. In a device that converts and outputs a converted signal as a signal to be recorded on a recording medium, the composite color video signal is supplied, and its passband characteristic increases as the frequency increases in the low frequency conversion carrier color signal band, and a comb-shaped filter for filtering the carrier color signal, which is configured to include at least a bandpass filter selected to have a characteristic of passing the carrier color signal, and a delay circuit that delays the composite color video signal by one horizontal scanning period. , a trap circuit for supplying the composite color video signal delayed or undelayed by the one horizontal scanning period and blocking the passage of the color subcarrier frequency and its neighboring frequency bands; and the one horizontal scanning period delay. The resulting composite color video signal and the output carrier color signal of the comb-shaped filter are respectively added, and the result is a flat characteristic in the low frequency band, and at least f_H/2 (however, f_H is horizontal) in the low frequency band. It exhibits a comb-shaped filter characteristic in which the pass band is an even number multiple of the scanning frequency) and the attenuation band is an odd number multiple of f_H/2.
an adder circuit for extracting a luminance signal imparted with a frequency characteristic in which the level of the attenuation range approaches the level of the passband as the frequency decreases; and when the signal-to-noise ratio of the composite color video signal is larger than a certain value A switch that selectively outputs the output signal of the trap circuit and selects and outputs the output signal of the adder circuit when the output signal is smaller than the certain value; 1. A recording information signal converting device comprising a circuit that generates a range-converted carrier color signal and band-sharing multiplexes this signal to the output luminance signal of the switch.