JPS5940356B2 - Image information reproducing device - Google Patents

Description

[Detailed Description of the Invention] The so-called NT Sobo style color television signal (hereinafter referred to as
television is written as T), a color subcarrier having a frequency value that is a half-odd multiple of the horizontal scanning frequency value and located in the high range of the luminance signal band is modulated by the color signal,
When recording and reproducing a color video signal of a color TV system in a signal format in which a luminance signal and a chroma signal are band-sharing multiplexed within the band of the luminance signal, limitations of the frequency characteristics of the recording medium and recording/reproducing system, and For example, NT
When recording and reproducing an SC color video signal, the chroma signal has a color subcarrier frequency value of 3.57954.
5MHz (hereinafter referred to as 3.58MHz) to 1.
The frequency is converted to a low frequency converted chroma signal of 534090714 MHz (hereinafter referred to as 1.53 MHz), and a signal obtained by band sharing multiplexing of this low frequency converted chroma signal and a luminance signal is recorded and reproduced as a frequency modulated wave. In this way, recording and reproduction are possible within the limits of the frequency characteristics of the recording medium and the recording/reproducing system, and the influence of speed fluctuations of the recording medium on reproduced colors is reduced.

By the way, the color video signal of the first color T method, which has a signal form in which the low-frequency converted chroma signal and the luminance signal are band-sharing multiplexed within the band of the luminance signal, is converted into a frequency modulated wave. The above-mentioned signal processing circuit in an image information reproducing apparatus includes a signal processing circuit capable of reproducing a recorded signal from a recording medium, converting it into an NTSC color video signal, and supplying the signal to a TV receiver. The low frequency converted chroma signal is deleted from the first color TV system color video signal obtained by FM demodulation of the recorded signal reproduced from the recording medium to create a luminance signal, and the low frequency converted chroma signal is converted into the second color video signal. A color video signal of the second color T method (a color video signal of the NTSC method) is obtained by adding the signal obtained by frequency conversion to a regular chroma signal in the color T method to the luminance signal. In addition, the means for separating the luminance signal and chroma signal in the signal processing circuit consists of a 1H delay circuit (1H delay line), an inverter, and an adder circuit. A comb filter is used.

On the other hand, in the signal reproduced from the recording medium, for example, there may be a dropout of the signal due to uneven coating or falling off of the magnetic paint on the magnetic tape, or a dropout of the signal due to the reproduction needle flying off the recording medium disk. Therefore, image information reproducing apparatuses are often equipped with means for compensating for missing signals in the reproduced signal. As means for compensating for the missing signal in the reproduced signal mentioned above, various types of means have been proposed in the past, but using the statistical properties of the T signal,
A widely used method for compensating for missing signals is one that detects when a signal is missing and inserts a signal from one horizontal scanning period earlier into the missing part of the signal as a missing compensation signal. In addition, as a generator of the compensation signal at the time of signal loss described above, a 1H delay circuit (1H
(delay line) is used.

An image information reproducing apparatus that uses the 1H delay line used in the above-mentioned comb filter and the 1H delay line that should be provided in the generator of the compensation signal (missing compensation signal) at the time of signal loss. It is also known to constitute.

By the way, the frequency band of the low frequency chroma signal that has been low frequency converted when recording and reproducing the color video signal is 1.53MH.
It has been clarified through various experiments conducted by the applicant's company and examination of the results that if the center frequency is set to z, image quality is likely to deteriorate due to various causes. Ta.

In other words, the comb is used to separate the luminance signal and chroma signal by utilizing the property of the color video signal that the spectrum of the luminance signal and the spectrum of the chroma signal are distributed without overlapping each other. The comb-type filter does not have ideal comb-type characteristics due to the 1H delay line used to construct it not having a sufficiently wide band and other reasons. The separation of the luminance signal and chroma signal by the filter is not complete, therefore, the chroma signal component (1
．． 53 MHz) may appear as noise on the playback screen, or the normal luminance signal may be damaged, especially the transient portion of the signal, resulting in deterioration of the luminance signal. As is well known, the frequency band around 1.53 MHz occupies the main frequency band in the luminance signal, so it is natural that the deterioration of the luminance signal in this part will have a large negative effect on the image quality. 1. Remaining in the luminance signal without being removed.
Since the 53 MHz chroma signal is also in a low frequency band (1.53 MHz) that generates noticeable noise in the reproduced image, this noise also greatly deteriorates the image quality. In this way, when the frequency band of the low-pass converted chroma signal is set to the frequency band around 1.53h,
Because the deterioration of the reproduced image is significant, the applicant company has implemented a low-pass conversion method that exhibits a frequency value of 5/7 (approximately 2.56 MHz) relative to the regular color subcarrier frequency (3.58 MHz). He proposed that the image quality of reproduced images could be greatly improved by using a color video signal in which a low-frequency converted chroma signal with a color subcarrier was band-sharing multiplexed with a luminance signal for recording and reproduction, and that the image quality of reproduced images could be greatly improved. We have proposed a recording/reproducing composite color video signal processing circuit having a low frequency converted chroma signal occupying a nearby frequency band.

FIG. 1 is a block diagram of an example of an image information reproducing apparatus including a signal processing circuit proposed by the applicant company mentioned above.

In FIG. 1, reference numeral 1 indicates the input of a recording/reproduction signal having a signal form in which a low-pass conversion chroma signal and a luminance signal are band-sharing multiplexed such that the frequency value of the low-pass conversion color subcarrier is 2.56 MHz. The recording/reproduction signal supplied to this input terminal 1 is supplied to the missing signal compensation switch circuit 3, and is also supplied to the subtractor 15 via the delay circuit 14 as its minuend signal. The aforementioned missing signal compensation switch circuit 3 and the below-described missing signal compensation switch circuit 20 are switched by supplying switching control signals from a missing signal detector (not shown) to their respective control terminals 2 and 30. Perform control operations. In a state where signal loss is not detected, the loss signal compensation switch circuit 3 supplies the input signal to the amplitude modulator 5, and the loss signal compensation switch circuit 20 converts the output signal from the subtracter 15 into a luminance signal. It is sent to the output terminal 32 of.

Further, when a signal loss occurs and a control signal is supplied to the control terminals 2 and 30, the loss signal compensation switch circuit 3 transfers the composite color video signal for loss compensation obtained from a circuit described later to the amplitude modulator 5. On the other hand, the missing signal compensation switch circuit 20 sends out a luminance signal for missing compensation obtained from a circuit described later to the luminance signal output terminal 32. The above-mentioned amplitude modulator 5 has a 6.14M signal from a crystal VCO 4 (voltage controlled oscillator configured with a crystal oscillator).
An oscillation wave of Hz is given as a carrier wave, and therefore the output signal of the amplitude modulator 5 has a center frequency of 3.58M.
When passed through a bandpass filter 6 having a pass band width of ±500 KHz in Hz, the low-converted chroma signal band signal in the recording/reproducing signal supplied to the input terminal 1 is converted into a normal chroma signal band, that is, 3. A signal frequency-converted to a chroma signal band of 58 cells is obtained.

The normal chroma signal band signal output from the bandpass filter 6 is applied to a comb filter CF constituted by a 1H delay circuit 7 and a subtracter 8 (inverter and adder circuit), and is also applied to a burst gate. Also given to 9.

The comb filter CF described above sends a regular chroma signal to the output terminal 31 by a well-known operation, and the comb filter C
The output signal from F is also provided to frequency converter 12.
The phase comparator 11 to which the color burst signal extracted by the burst gate 9 described above is supplied has a phase difference of 3.58.
A reference oscillator 10 that oscillates a reference wave with a frequency value of MHz.
Therefore, the crystal VCO 4 to which the phase discrimination output from the phase comparator 11 described above is applied, converts the frequency value of the color subcarrier in the signal that has passed through the bandpass filter 6 into the frequency value of the color subcarrier in the signal passed through the bandpass filter 6. The modulator 5 transmits a carrier wave having a frequency value that can match the oscillation frequency of the reference oscillator 10.
give to

Furthermore, the carrier wave of the crystal VCO 4 is transmitted to the frequency converter 12.
As a result, the output side of the frequency converter 12 described above has the same time axis fluctuation as the low frequency converted color video signal in the recording/reproducing composite color video signal supplied to the input terminal 1. A signal containing a low-pass converted color video signal indicating . is the same as the low frequency converted color video signal in the recording/reproduction composite color video signal supplied to the input terminal 1. Therefore, the subtracter 15 outputs only the luminance signal in the recording/reproducing composite color video signal supplied to the input terminal 1 when no signal loss occurs. The signal appearing on the output side of the amplitude modulator 5 described above has a center frequency of 7.16 MHz (3.58×2
After a time delay of one horizontal scanning period is given by a 1H delay circuit 16 (MHz), the signal is demodulated by an amplitude demodulator 17, and then a low-pass filter gives a half-wavelength delay to a 2.56MHz signal. 18, and is applied to the missing signal compensation switch circuit 3 as a composite color video signal for compensation in the event of signal loss.

Furthermore, the demodulated signal from the amplitude demodulator 17 is passed through a low-pass filter 19 so that only its low-frequency signal component is supplied to the missing signal compensation switch circuit 20 as a luminance signal for compensation when the signal is missing. .

In the image information reproducing device already proposed by the applicant company, which has the configuration shown in the first diagram above, when there is no signal loss, that is, when the input signal is normal, the input terminal 1 is A regular chroma signal is extracted by a comb-shaped filter CF from a signal obtained by frequency-converting the low frequency converted chroma signal in the supplied recording and reproduction color video signal to the frequency band of the regular chroma signal, and is sent to the output terminal 31. is,
Further, a luminance signal obtained by subtracting the low-frequency converted chroma signal produced by the frequency converter 12 from the recording/reproduction color video signal supplied to the input terminal 1 by the subtracter 15 is sent to the output terminal 32. ing. In addition, when a signal is missing, after the modulated wave output from the amplitude modulator 5 is demodulated by the amplitude demodulator 17 via the 1H delay circuit 16,
The signal phase-shifted by the low-pass filter 18 which gives a half-wavelength delay to the 2.56 MHz signal is amplitude modulated via the missing signal compensation switch circuit 3 as a composite color video signal when the signal is missing. The chroma signal in the 3.58 MHz band at the time of signal loss is sent from the comb filter CF to the output terminal 31, and the demodulated signal from the amplitude demodulator 17 is The low-frequency signal of the demodulated signal obtained through the low-pass filter 19 is sent to the output terminal 32 via the missing signal compensation switch circuit 20 as a luminance signal at the time of signal loss. In this way, in the image information reproducing apparatus shown in the first figure, it is possible to obtain a luminance signal and a chroma signal even when the input signal is normal and when the signal is missing.

In the image information reproducing apparatus having the configuration shown in FIG. 1, the composite color video signal supplied to the input terminal 1 appears on the output side of the missing signal compensation switch circuit 3 when the signal is in a normal state. Furthermore, since a composite color video signal for loss compensation appears when a signal is missing, if the input signal to the delay circuit 14 in FIG. 1 is supplied from the output side of the loss compensation switch circuit 3, the input Even when the signal is in a normal state or when a signal is missing, a luminance signal is obtained from the subtracter 15. Therefore, the input signal to the delay circuit 14 is input from the output side of the switch circuit 3 for compensating for missing signals. In this case, it becomes possible to omit the use of the missing signal compensation switch circuit 20, the low-pass filter 19, etc., but the above-mentioned simplification of the configuration in the previously proposed device shown in Figure 1 The reason why this is not done is as follows. In other words, the compensation operation for missing signals necessarily involves a certain degree of imperfection, and is also affected by the frequency characteristics of the signal transmission system in the device, so It is difficult to make the signal level of the spectral luminance signal component desirable and at the same time make the cancellation operation of the low frequency converted chroma signal in the 2.56 MHz band in the missing signal compensator desirable. A luminance signal band of about 1 MHz is sufficient for practical purposes, and the difference in the signal level of the luminance signal in the missing signal compensation section mentioned above and the residual part of the low-frequency converted chroma signal in the 2.56-band This is because the presence of such a signal greatly impairs the function of compensating for missing signals.

Now, in the previously proposed image information reproducing apparatus shown in FIG. The 2.56 M
Hz band low frequency conversion chroma signal is frequency converted to regular 3.58 carved band chroma signal, center frequency is 3.58M
A regular chroma signal is extracted by a comb filter CF including a 1H delay circuit 7 of Hz, and a frequency-converted composite color video signal is extracted with a center frequency of 7.16MF-1z.
1H delay circuit 16, amplitude demodulation circuit 17, low pass filter 1
A circuit consisting of 8 circuits is used to generate a composite color video signal to be used in the event of a signal loss. A delay circuit 16 is used.

Two 1H delay circuits 7 used in the above device
, 16, the above two 1H As the delay circuits 7 and 16,
It is necessary to use a device that has a sufficiently wide passband width compared to the frequency band of the signal that is to be passed through it, but on the other hand, in consumer equipment, cost must also be considered. As the delay circuits 7 and 16 used in the device, it is necessary to use low-cost products such as mass-produced products. By the way, the two 1H delay circuits 7 used in the device shown in the first figure
, 16, as the 1H delay circuit 7, a commercially available mass-produced 1H delay line with a center frequency of 3.58 MHz and a passband width of approximately ±1 MHz can be used successfully. Since the 1H delay circuit 16 with a center frequency of 7.16° is not a mass-produced product, its price is several times higher than that of the 1H delay circuit 7 with a center frequency of 3.58MHz, and its passband is The width of the 1H delay circuit 16 in the image information reproducing apparatus having the configuration shown in FIG.
When a semi-mass-produced 1H glass delay line, which is relatively easy to obtain, is used, a composite color signal is applied to the amplitude modulator 5 as a loss compensation signal via the loss signal compensation switch circuit 3 when a signal is lost. The video signal has a part of its low frequency converted chroma signal lost, which deteriorates the quality of the compensation chroma signal when the signal is missing.

This point will be explained in more detail with reference to FIGS. 2 and 3 as follows. That is, a composite color video signal having a chroma signal in the frequency band of the regular chroma signal as shown in FIG.
．． It is recorded and played back as a composite color video signal that has been frequency-converted to a low-frequency converted chroma signal in the 56MHz band.
．． When the amplitude modulator 5 is supplied with a carrier wave of 6.14 MHz as a modulation signal and amplitude modulation is performed, the output side of the amplitude modulator 5 receives the modulation signal shown in FIG. A modulated wave with upper and lower sidebands generated by the signal is generated, and the 1H delay circuit 16 to which this modulated wave is applied is a semi-mass-produced 1H glass delay line with a center frequency of 7.16 MHz, as described above. If the passband characteristic of this 1H delay circuit 16 is not as wide as the curve shown by the dashed-dotted line in FIG. 3b, the signal passing through this 1H delay circuit 16 will be 6.14MH
z carrier wave, most of the upper sideband, and only a portion of the lower sideband (the luminance signal and the lower sideband are not shown in FIG. 3b).

This point is also the same in FIG. 3a}. Generally, in a 1H delay circuit, the characteristics at the boundary between the passband and the cutoff band are disturbed due to the presence of spurious, etc., so the signal given to the amplitude demodulator 17 through the 1H delay circuit 16 is as follows. Part of the low frequency converted chroma signal may be lost due to limitations due to the passband characteristics of the 1H delay circuit 16, or the quality of the signal may deteriorate due to the influence of spurious signals from the 1H delay circuit 16. As a result, the composite color video signal used as a loss compensation signal when a signal is lost becomes a signal with degraded quality. The above-mentioned drawbacks of the previously proposed image information reproducing device shown in FIG. A similar problem occurs in an image information reproducing device that uses a 1H delay line and a 1H delay line that should be provided in the generator of a compensation signal when a signal is lost. This will be explained with reference to Figure b and Figure 3A.

FIG. 2b shows a composite color video signal having a low frequency converted chroma signal (1.56L band chroma signal) in a known conventional device. b A composite color video signal as shown is supplied as a modulation signal to an amplitude modulator provided with a carrier wave of 5.11 MHz, and the modulated wave obtained from the amplitude modulator is 1H delay line (1H delay line for PAL method is used), but in this case, the above 1H delay line is applied to the third
As shown in Figure A, only the 5.11C carrier wave, most of the lower sideband, and a portion of the upper sideband are allowed to pass through. 1H delay line}, the chroma signal used as the dropout compensation signal in this known conventional device also has a degraded signal quality.

In this case, not only the loss compensation signal but also the regular chroma signal (output signal from the comb filter) becomes degraded. The present invention has been made for the purpose of providing an image information reproducing device that does not have the problems described above in the known conventional device described above and the proposed device shown in FIG. The contents of the image information reproducing apparatus will be explained in detail with reference to the accompanying drawings, FIG. 4 and subsequent figures.

FIGS. 4 and 6 are block diagrams of different embodiments of the image information reproducing apparatus of the present invention, and in these FIGS. The same drawing numerals as those used in Fig. 1 are used for constituent parts that are equivalent to the constituent parts, and
The same drawing numerals are used for corresponding components in FIGS. 4 and 6.

In Fig. 4, as shown in Fig. 2c, input terminal 1 has a chroma signal and a luminance signal Y, which have been low-pass converted so that the frequency value of the color subcarrier is 256 MHz, and are band-sharing multiplexed. A recording/reproducing signal based on a composite color video signal is supplied as an input signal.

The input signal described above is applied as an input signal to the first frequency converter 21 to which a 6.14 MHz carrier wave is applied, and is also applied to the second missing signal compensation switch circuit 23.
and is also added to the delay circuit 14 as an input signal. The output of the first frequency converter 21 described above is applied to the first missing signal compensation switch circuit 3 via a bandpass filter 6 having a center frequency of 3.58 MHz.

The output signal of the first missing signal compensation switch circuit 3 is a signal in the regular chroma signal band {a signal in the 3.58 MHz band shown with hatching in FIG. 1H delay circuit 7 with a frequency of 3.58MHz
and a comb filter CF constituted by a subtracter 8;
burst gate 9. The output signal from the comb filter CF is given to the chroma signal output terminal 31 and the second frequency converter 12.
The output signal from 2 passes through a low-pass filter 13 to a subtractor 15.
Furthermore, the signal from the delay circuit 14 is given as a subtracted signal to the subtracter 15, and the output signal of the subtracter 15 is given as a third luminance signal in normal conditions. The luminance signal is sent to the luminance signal output terminal 32 via the missing signal compensation switch circuit 20.

The output signal from the phase comparator 11 that performs a phase comparison between the color burst signal extracted by the burst gate 9 and the oscillation wave of 3.58 skin from the reference oscillator 10 has the oscillation frequency of the crystal VCO 4. The oscillation wave from the crystal VCO 4 is given to the first and second frequency converters 21 and 12.

The output signal from the 1H delay circuit 7 in the comb filter CF described above is given to the subtracter 8, and
The signal is applied to the first missing signal compensation switch circuit 3 as a missing signal compensating signal via a delay circuit 22 which provides a time delay corresponding to a half wavelength of the 8 MHz signal.

Further, the 3.58h oscillation wave from the reference oscillator 10 described above is transmitted to the second missing signal compensation switch circuit 2 described above.
The output signal from 3 is also given as a carrier wave to an amplitude modulator 5, which is adapted to be given as a modulation signal.

First to third missing signal compensation switch circuits 3, 23, 2
Needless to say, each control terminal 2, 33, 30 at 0 is supplied with a switching control signal from a missing signal detector (not shown) when a signal is missing. The amplitude modulator 5 outputs a modulated wave in which the 3.58 MHz carrier wave given to it by the reference oscillator 10 is modulated by the modulation signal supplied from the second missing signal compensation switch circuit 23. The signal is then applied to a 1H delay circuit 24 having a center frequency of 3.58 MIz.

The 1H delay circuit 24 described above has a passband width of ±1L.
Therefore, the amplitude demodulator 25 from the 1H delay circuit 24
The signal given to is a modulated wave corresponding to the low frequency portion of the luminance signal, as shown in FIG. 5b.

In FIG. 5B {the same applies to FIG. 5A}, the curve shown by the dashed-dotted line shows the passband characteristic of the 1H delay circuit 24. Therefore, the amplitude demodulator 25 outputs the low-frequency signal component of the luminance signal in the composite color video signal as a demodulated signal and supplies it to the low-pass filter 19 and the trap circuit 26. The output signal is supplied to a third switch circuit 20 for compensating for missing signals as a luminance signal for compensating when a signal is missing, and a trap circuit 26 removes unnecessary frequency values such as 3.58M1I x 17.16MHz. The demodulated signal from the amplitude demodulator 25 from which the signal component has been removed is given to the second missing signal compensation switch circuit 23 as a luminance signal for compensation when the signal is missing.

In the image information reproducing apparatus of the present invention shown in FIG. 4 described above, the loss compensation signal used when a signal is lost has a center frequency of 3.58 MHz for the chroma signal band signal and the luminance signal, respectively. 1H of mass-produced products
Since the delay circuits 7 and 24 are used in the circuit, the device having the configuration shown in FIG. It is clear that all the points mentioned above can be satisfactorily resolved.

That is, the missing signal compensation signal corresponding to the chroma signal band is transmitted through the missing signal compensation switch circuit 3 and the comb filter C.
In this circuit, the signal in the chroma signal band is passed through the 1H delay circuit 7 with a center frequency of 3.58 MHz.
With respect to the passband characteristics of In addition, the second missing signal compensation switch circuit 23, the amplitude modulator 5, and the center frequency are 3.58 MHz.
1H delay circuit 24, amplitude demodulator 25, trap circuit 2
In the luminance signal generation circuit for compensation when a signal is missing, such as 6, the center frequency is 3.58 MHz.
As shown in FIG. 5b, the H delay circuit 24 effectively extracts only the low-frequency portion of the luminance signal to obtain a luminance signal for compensation when the signal is missing. Therefore, the image information reproducing device of the present invention shown in FIG. 4 has better image quality than conventional devices and previously proposed devices, not only in normal times when there is no signal loss, but also even when signal loss occurs. It is possible to create a signal from which a reproduced image can be obtained.

In addition, in the previously proposed device shown in the first figure, 2.56M
The luminance signal at the time of signal loss is phase-shifted by a low-pass filter 18 that gives a time delay of half a wavelength to the Hz signal, but the present invention shown in FIG. Since there is no such problem with the device, from this point of view as well, the device of the present invention can be said to be superior in terms of improved image quality. The image information reproducing apparatus of the present invention shown in FIG.
The structure is simplified by replacing the circuit with one missing signal compensation switch circuit 29.

That is, in the apparatus shown in FIG. 6, a low-pass filter 19 is connected to the input terminal 1, and the low-pass signal component (low-pass component of the luminance signal) in the composite color video signal supplied to the input terminal 1 is filtered. This and the signal of the chroma signal band obtained at the output side of the bandpass filter 6 are added together by an adder 27 and applied to the missing signal compensation switch circuit 29, and the 1H delay circuit in the comb filter CF is added. The output signal of 7 is sent to the half-wavelength delay circuit 22.
The adder 28 adds the delayed signal and the output signal from the trap circuit 26 and supplies it to the missing signal compensation switch circuit 29. , the output signal of the trap circuit 26 is applied to the comb filter CF, the burst gate 9, and the amplitude modulator 5, and the output signal of the trap circuit 26 is applied to the missing signal compensation switch 20.
By making it possible to provide a device with a performance similar to that of the device shown in FIG. 4, the device shown in FIG.
This can be achieved by a circuit configuration using fewer missing signal compensation switches. The device shown in FIG. 6 can be configured by the adder 2.
This is because the two signals added by 7 and 28 have different frequency bands. Note that 34 in FIG. 6 is a terminal for applying a switching control signal. The fact that the device shown in FIG. 6 operates in the same manner as the device shown in FIG.

As is clear from the above detailed explanation, the image information reproducing apparatus of the present invention includes a circuit for generating a signal in a chroma signal band for compensation when a signal is missing, and a generation circuit for generating a signal in a chroma signal band for compensation when a signal is missing. An inexpensive 1H delay circuit with a center frequency of 3.58 MHz is used in each of the circuits, and each of the 1H delay circuits has a negative effect on the signal passing through them due to its passband characteristics. Since the circuit configuration is such that no damage is caused, the present invention makes it possible to provide an image information reproducing device at a low cost and with better performance than previously proposed devices.

In addition, like the previously proposed device, the device of the present invention processes composite color images in which the low-frequency converted chroma signal is in the 2.56 MHz band, so the drawbacks of the conventional device described above are not present. Needless to say, the problem has been satisfactorily solved by the image information reproducing device invented by Wood.

[Brief explanation of the drawing]

Figure 1 is a block diagram of the previously proposed image information reproducing device;
Figures a-c, Figures 3A and b, Figures 5A and b, etc. are explanatory characteristic example diagrams, and Figures 4 and 6 illustrate different embodiments of the image information reproducing device of the present invention. This is a block diagram of the same. 1... Input terminal, 2, 30, 33, 34...
... Control terminal, 3, 20, 23, 29 ... Switch circuit for compensating for missing signals, 4 ... Crystal VCO15 ... Amplitude modulator, 6 ...・Band filter, 7, 16, 24...1H delay circuit,
8,15...゜゜゜subtractor, 9. ... Burst gate, 11 ... Phase comparator, 10 ...
・Reference oscillator, 12, 21... Frequency converter, 13, 18, 19... Low pass filter, 14, 2
2...delay circuit, 17, 25...amplitude demodulator, 26...trap circuit.

Claims (1)

[Claims] 1. A signal in the frequency band of a low-pass converted chroma signal in a recording/reproducing composite color video signal having a signal form in which a low-pass converted chroma signal and a luminance signal are band-sharing multiplexed is a normal chroma signal. A signal from a first frequency converter, which is configured to be frequency-converted into a signal in a frequency band of the signal, is applied to a first missing signal compensation switch circuit as a normal input signal, and the first The output signal of the missing signal compensation switch circuit is applied to a comb-type filter including a 1H delay circuit, and a chroma signal in the frequency band of the regular chroma signal is obtained from the comb-type filter and output. At the same time, a signal for compensating for loss in the frequency band of the chroma signal is obtained from the output signal of the 1H delay circuit in the comb-type filter described above, and this signal is sent to the first switch circuit for compensating for a loss signal for compensation at the time of signal loss. Oscillation from a voltage controlled oscillator whose oscillation frequency is controlled based on the phase comparison result between the color burst signal in the input signal to the comb filter described above and the reference wave from the reference oscillator. The wave is applied to the first frequency converter described above, and is also applied to the second frequency converter that converts the output signal from the comb filter to a low frequency converted chroma signal, The oscillation wave from the reference oscillator described above is applied as a carrier wave to the amplitude modulator to which the composite color video signal is applied as a normal modulation signal via the second missing signal compensation switch circuit, and the amplitude modulation described above is performed. The output signal from the device is delayed by a 1H delay circuit that can pass only the signal component corresponding to the low frequency component of the recording/reproduction composite color video signal in the output signal, and then the signal obtained by demodulating the signal is obtained. , the second missing signal compensation switch circuit and the third
The output signal of the second frequency converter is supplied as a luminance signal for compensation at the time of a signal loss to the loss signal compensation switch circuit of the second frequency converter. The luminance signal obtained by removing the low frequency converted chroma signal is given to the third missing signal compensation switch circuit as a normal luminance signal, and the luminance signal is output as the output of the third missing signal compensation switch circuit. An image information reproducing device that obtains a signal. 2. The signal in the frequency band of the low-pass converted chroma signal in the recording/reproduction composite color video signal having a signal form in which the low-pass converted chroma signal and the luminance signal are band-sharing multiplexed is the signal in the frequency band of the regular chroma signal. A composite signal of the frequency band signal of the regular chroma signal in the signal from the first frequency converter whose frequency is converted to 1 and the low frequency signal of the recording/reproduction composite color video signal is input to one side. The output signal of the missing signal compensation switch circuit, which is designed to be given as a signal, is given to a comb-shaped filter including a 1H delay circuit, and the frequency band of the regular chroma signal is filtered from the comb-shaped filter. A voltage whose oscillation frequency is controlled based on the phase comparison result between the color burst signal in the input signal to the comb filter and the reference wave from the reference oscillator. Applying the oscillation wave from the controlled oscillator to the first frequency converter, and also applying it to the second frequency converter that converts the output signal from the comb filter into a low frequency converted chroma signal, and further , for an amplitude modulator in which the output signal from the missing signal compensation switch circuit described above is given as a modulation signal,
The oscillation wave from the reference oscillator described above is given as a carrier wave, and only the signal component corresponding to the low frequency component of the recording and reproduction composite color video signal in the output signal from the amplitude modulator is passed through. When a signal is missing in the frequency band of the luminance signal for compensation in the case of signal loss obtained by demodulating after being delayed by a 1H delay circuit, and the chroma signal obtained from the output of the 1H delay circuit in the comb filter described above. supplying the compensation signal to the aforementioned missing signal compensation switch circuit as the other input signal, and furthermore,
The luminance signal for compensating when the signal is missing is supplied as a luminance signal for compensating when the signal is missing to another missing signal compensation switch circuit different from the above-mentioned missing signal compensation switch circuit, and , the luminance signal obtained by removing the low-frequency converted chroma signal in the output signal of the second frequency converter from the signal obtained by delaying the recording/reproduction composite color video signal is used for the another missing signal compensation described above. An image information reproducing device configured to provide a brightness signal to a switch circuit as a normal brightness signal, and obtain the brightness signal as an output of another switch circuit for compensating for missing signals.