JP3388077B2 - Video signal processing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal processing device relating to a color demodulation circuit for PAL television signals.

[0002]

2. Description of the Related Art In recent years, internationalization has progressed, and home video cassette recorders (hereinafter referred to as VCRs) compatible with a plurality of television systems have been developed. In this, N
There is a technique that enables a video cassette on which a video of a TSC television system (hereinafter, referred to as NTSC system) is recorded to be reproduced in a VCR for PAL television system (hereinafter, referred to as PAL system). In this technology, in order to project an NTSC system recorded image on a television receiver capable of projecting the PAL system, the vertical synchronizing frequency and the horizontal synchronizing frequency are made equal to the NTSC system and only the color modulation system is set to P.
There is a VCR that converts to an output learned from the AL method. Hereinafter, this special television system is referred to as PAL60 system.

Here, demodulation of color difference signals in a television receiver compatible with the PAL system is performed by calculating a signal immediately after demodulating a color subcarrier and a signal obtained by delaying the signal by one horizontal period. (This calculation is hereinafter referred to as adjacent scan line calculation). In the VCR that outputs the PAL60 system signal, the color demodulation mechanism of the PAL system receiver described above is used, and the amplitude of the signal after the color subcarrier demodulation is double that of the normal PAL system, and the color Uses a method that simplifies the color difference signal modulation circuit (hereinafter referred to as double-amplitude PAL60 method) by outputting a signal that alternately repeats scanning lines where the signal amplitude after subcarrier demodulation is 0. There is something that was there.

On the other hand, in a television receiver, there is a tendency to incorporate digital signal processing in order to easily realize complicated image quality correction and aspect ratio conversion. When digitally processing the signal input in analog, A / D
The converter performs A / D conversion, but in order to minimize the influence of quantization distortion, the conventional video signal processing apparatus adjusts the signal input maximum amplitude to the input maximum amplitude of the A / D converter. Therefore, in a PAL system receiver that is assumed to be connected to a PAL60 system VCR, when the signal processing after color subcarrier demodulation is digitized, the amplitude of the analog signal after color subcarrier demodulation becomes maximum. Amplitude PA
The maximum amplitude of the input to the A / D converter was adjusted according to the L60 system.

[0005]

In the conventional video signal processing apparatus as described above, it is necessary to make the maximum input amplitude of the A / D converter to be twice the amplitude of the normal PAL system.
Only half the resolution of the A / D converter can be used for signals of the AL system. Also, for a signal of the double amplitude PAL60 system, the desired resolution can be obtained by A / D conversion.
Since the adjacent scanning line calculation is performed as in the case of the normal PAL input, the resolution becomes the same as that in the normal PAL input.
That is, there is a problem that the accuracy is only half that of the resolution of the A / D converter.

The present invention provides a video signal processing device having a circuit for demodulating a color difference signal from a PAL video signal,
Digital signal processing after color subcarrier demodulation is performed by A / D of the color difference signal when a standard PAL system signal is input.
It is an object of the present invention to support a double-amplitude PAL60 system in which a color-difference signal having an amplitude twice that of a normal color-difference signal that appears every other scanning line is simplified without lowering the resolution during conversion.

[0007]

In order to solve the above problems and achieve the object, the first means of the present invention is to determine whether the color difference signal is a normal PAL system color difference signal or the PAL60 system color difference signal. It has a detection means, and is provided with means for adjusting the amplitude of the analog color difference signal input to the A / D converter to an optimum amplitude for A / D conversion.

According to the first means of the present invention, the analog input maximum amplitude of the A / D converter is adjusted to the maximum amplitude of the color difference signal of the normal PAL system, and the color difference is obtained for the signal of the double amplitude PAL60 system. By adjusting the amplitude of the signal to the amplitude of the normal PAL system, the double amplitude P
Even in the AL60 system, analog color difference signals can be converted into digital signals by using the maximum resolution of the A / D converter.

The second means of the present invention is a normal PA.
It has means for judging whether it is the L system color difference signal or the PAL60 system color difference signal, and comprises means for selecting the A / D convertible maximum amplitude of the A / D converter.

According to the second means of the present invention, by adjusting the maximum analog input amplitude of the A / D converter in accordance with the amplitude of the color difference signal input to the A / D converter, the normal PAL system is used. The analog color difference signal can be converted into a digital signal by using the resolution of the A / D converter to the maximum in both the above signal and the double amplitude PAL60 system.

The third means of the present invention comprises a detecting means for monitoring the specified amplitude of the input analog color difference signals and determining that the amplitude is larger than the specified amplitude of the PAL system as a PAL60 system signal. A means for maximally utilizing the resolution of the D converter is provided.

According to the third means of the present invention, by monitoring the specified amplitude of the input analog color difference signals, it is possible to automatically detect the normal PAL system or the double amplitude PAL60 system. By optimizing the amplitude of the analog color difference signal input to the A / D converter or the maximum A / D convertible amplitude of the A / D converter based on the detection result, A
It is possible to convert the analog color difference signal to digital by using the maximum resolution of the / D converter.

The fourth means of the present invention comprises means for detecting that the input color difference signal is a signal which repeats the presence / absence of every other scanning line, and maximizes the resolution of the A / D converter. Equipped with means to use.

According to the fourth means of the present invention, it is possible to automatically detect the normal PAL system or the double-amplitude PAL60 system by judging the presence or absence of the color difference signal. By optimizing the amplitude of the analog color difference signal input to the A / D converter or the maximum A / D convertible amplitude of the A / D converter, the resolution of the A / D converter is used to the maximum. The analog color difference signal can be converted to digital.

Further, a fifth means of the present invention comprises means for obtaining the specified amplitude of the color difference signal of the third means and detecting whether it is larger than the signal of the normal PAL system. In order to perform A / D conversion of the amplitude of the analog color difference signal, the means for detecting that the color difference signal of means 4 is a signal for repeating the presence / absence of every other scanning line is provided, and the above two detecting means are used in combination. It is provided with a means for adjusting to an optimum amplitude or a function for selecting the maximum A / D convertible amplitude of the A / D converter.

According to the fifth means of the present invention, the double amplitude PA
The L60 method is used in combination with the determination based on the specified amplitude of the color difference signal, which is the third means, and the determination based on the presence or absence of the color difference signal, which is the fourth means, to improve the accuracy and to detect the detection result. By optimizing the amplitude of the analog color difference signal input to the A / D converter or the maximum A / D convertible amplitude of the A / D converter, the resolution of the A / D converter is used to the maximum. The analog color difference signal can be converted to digital.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. 1 to 4.

(Embodiment 1) FIG. 1 is a block diagram showing a configuration of a video signal processing apparatus according to Embodiment 1 of the present invention, and corresponds to claims 1, 2, and 4.

In the circuit for demodulating a color difference signal from a PAL system video signal shown in FIG. 1, 1 is an analog amplitude adjuster, which has a gain (× 1 (equal magnification)) 11 and a gain (× 1/2 (2 minutes). 1 ×)) and 12. 2 is an A / D converter, 3 is an adjacent scanning line adder, and a delay line (1H-DELAY)
It consists of 31 and adder 32. Reference numeral 4 denotes a digital amplitude adjuster, which has a gain (× 1 (equal magnification)) 41 and a gain (× 1/2 (half)
42) and is composed of an amplifier or an attenuator. 5
Is a voltage comparator, which is composed of comparators 51 and 52 and OR53.
Reference numeral 6 is a control device. Each function of each of these components is
It has an analog amplitude adjuster 1 and an A / D converter 2 as A / D conversion means having a function of adjusting the resolution of the A / D converter 2 to the maximum extent, and delays the color difference signal by one horizontal period. Digital delay line (1H-DELAY)
And an adjacent scanning line adder 3 as a means for calculating a color difference signal delayed by the delay line and a color difference signal not delayed, that is, a color difference signal between adjacent scanning lines, in the A / D conversion means. A digital amplitude adjuster 4 is provided as a means for correcting a change in digital value after A / D conversion by adjustment for maximizing the use of resolution.
The voltage comparator 5 is provided as means for detecting that the color difference signal of the special PAL television signal in which the color difference signal having the amplitude twice that of the normal one exists every other scanning line. It has a control device 6 as means for controlling the analog amplitude adjuster 1 as the A / D conversion means and the digital amplitude adjuster 4 based on the above information.

Next, the operation of the video signal processing device having the above configuration will be described. The color difference signal immediately after demodulating the PAL color subcarrier is processed by the analog amplitude adjuster 1,
It is input to the A / D converter 2. The color difference signal converted into the digital signal by the A / D converter 2 is added by the adder 32 with the color difference signal of one horizontal period delayed by the delay line 31 of the adjacent scanning line adder 3 to obtain the digital amplitude adjuster 4 The change in the digital value subjected to the amplitude adjustment processing is corrected by. The comparators 51 and 52 of the voltage comparator 5 are the upper limit voltage (A-IN> VRE) of the analog input voltage of the A / D converter 2.
FH) and the lower limit voltage (A-IN <VREFL) are compared with the voltage of the color difference signal processed by the analog amplitude adjuster 1, and the voltage of the color difference signal is within the A / D convertible maximum amplitude of the A / D converter 2. It is detected whether it is output from OR53. Control device 6
Is the analog amplitude adjuster 1 according to the result of the voltage comparator 5.
And control the digital amplitude adjuster 4.

Normally, the gain of the analog amplitude adjuster 1 is set to “× 1 (equal magnification)” 11 and the gain of the digital amplitude adjuster 4 is set to “× 1/2 (one half)” 42. . In this state, the color difference signal of the normal PAL system is optimized. Here, when the color difference signal of the double amplitude PAL60 system, that is, the color difference signal of double the amplitude of the normal PAL system color difference signal is input to the analog amplitude adjuster 1, the output of the analog amplitude adjuster 1 is A / D converted. The voltage comparator 5 detects that it is out of the A / D convertible maximum amplitude range of the device 2, and sends a signal to the control device 6. The control device 6 detects that the input color difference signal has a double amplitude PAL60 based on the detection result of the voltage comparator 5.
If it is judged to be the system, the gain of the analog amplitude adjuster 1 is set to "× 1/2 (1/2)" 12 and the gain of the digital amplitude adjuster 4 is set to "× 1 (equal magnification)" 41. As a result, the video signal processing device of this embodiment is optimized for the color difference signals of the double amplitude PAL60 system.

As described above, by monitoring the amplitude of the input color difference signal, both the standard PAL system color difference signal and the double amplitude PAL60 system color difference signal are made to have a constant input amplitude to the A / D converter. , Even for the standard PAL system,
Even in the double amplitude PAL60 system, it is possible to demodulate color difference signals without deteriorating the quantization error.

(Embodiment 2) FIG. 2 is a block diagram showing a configuration of a video signal processing apparatus according to Embodiment 2 of the present invention, and corresponds to claims 1, 3 and 4.

In the circuit for demodulating a color difference signal from a PAL system video signal shown in FIG. 2, the same functional blocks as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. Here, 7 is a normal reference voltage source, 8 is a double amplitude reference voltage source,
Reference numeral 9 is a reference voltage switch, and 10 is an overrange detector.

The respective functions of these respective constituent devices are the normal reference voltage source 7 and the double amplitude reference as the A / D converting means having the function of adjusting the resolution of the A / D converter 2 to the maximum. It is a special PAL television signal color difference signal in which a voltage source 8, a reference voltage switch 9 and an A / D converter 2 are provided, and a color difference signal having an amplitude twice the normal is present every other scanning line. The control device 6 controls the reference voltage switch 9 and the digital amplitude adjuster 4 on the basis of the information of the overrange detector 10 as a means for detecting that.

Next, the operation of the video signal processing device having the above configuration will be described. The color difference signal immediately after demodulating the PAL color subcarrier is input to the A / D converter 2. A /
The D converter 2 uses the normal reference voltage source 7 and the double-amplitude reference voltage source 8 selected by the reference voltage switch 9 as the reference voltage for A / D conversion, so that A / D is adjusted according to the input amplitude. The maximum D-convertable amplitude can be switched. A / D
The color difference signal converted into the digital signal by the converter 2 is added by the adder 32 with the color difference signal of one horizontal period delayed by the delay line 31 of the adjacent scanning line adder 3 and added by the adder 32. The change in the digital value due to the operation is corrected by the digital amplitude adjuster 4. The overrange detector 10 monitors the digital signal output from the A / D converter 2 and detects the overrange so that the voltage of the color difference signal is the maximum amplitude that can be A / D converted by the A / D converter 2. Detects whether it is within the range. The control device 6 controls the reference voltage switch 9 and the digital amplitude adjuster 4 according to the result of the overrange detector 10.

Normally, the reference voltage switch 9 selects the normal reference voltage source 7, and the gain of the digital amplitude adjuster 4 is set to ".times.1 / 2 (1/2)". In this state, the color difference signal of the normal PAL system is optimized. Here, when the color difference signal of the double amplitude PAL60 system, that is, the color difference signal of double the amplitude of the normal PAL system color difference signal is input to the A / D converter 2, the overrange detector 10 detects the overrange, That is, it is detected that the A / D converter 2 is out of the A / D convertible maximum amplitude range, and a signal is sent to the control device 6.

When the control device 6 judges from the detection result of the overrange detector 10 that the input color difference signal is the double-amplitude PAL60 system, it causes the reference voltage switch 9 to select the double-amplitude reference voltage source 8. The gain of the amplitude adjuster 4 is set to “× 1 (equal magnification)” 41. As a result, the video signal processing device of the present embodiment is optimized for the color difference signals of the double amplitude PAL60 system.

As described above, by monitoring the amplitude of the input color difference signal and selecting the optimum reference voltage of the A / D converter, the quantum can be quantized for both the standard PAL system and the double amplitude PAL60 system. This makes it possible to demodulate the color difference signal without deteriorating the conversion error.

(Third Embodiment) FIG. 3 is a block diagram showing a configuration of a video signal processing apparatus according to a third embodiment of the present invention, and corresponds to claims 1, 2, and 5.

In the circuit for demodulating a color difference signal from a PAL system video signal shown in FIG. 3, blocks having the same functions as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. Here, 13 is a no-signal line detector, which is means for detecting that a color difference signal of a special PAL television signal in which a color difference signal having an amplitude twice as large as usual exists every other scanning line. Used as. Further, the control device 6 controls the analog amplitude adjuster 1 and the digital amplitude adjuster 4 based on the information from the no-signal line detector 13.

Next, the operation of the video signal processing device having the above configuration will be described. The color difference signal immediately after demodulating the PAL color subcarrier is processed by the analog amplitude adjuster 1,
It is input to the A / D converter 2. The color difference signal converted into the digital signal by the A / D converter 2 is added by the adder 32 and the color difference signal of one horizontal period delayed by the delay line 31 of the adjacent scanning line adder 3 to adjust the digital amplitude. The change in the digital value subjected to the amplitude adjustment processing is corrected by the instrument 4. The no-signal line detector 13 detects that the presence or absence of the color difference signal is alternately repeated every other scanning line. The control device 6 controls the analog amplitude adjuster 1 and the digital amplitude adjuster 4 according to the result of the no-signal line detector 13.

Normally, the gain of the analog amplitude adjuster 1 is set to "× 1 (equal magnification)" 11 and the gain of the digital amplitude adjuster 4 is set to "× 1/2 (1/2)" 42. . In this state, the color difference signal of the normal PAL system is optimized. Here, when the double-amplitude PAL60 system, that is, when a color difference signal in which the presence or absence of a color difference signal is alternately repeated every other scanning line is input, the no-signal line detector 13 causes the double amplitude P
It detects that it is the AL60 system and sends a signal to the control device 6. When the control device 6 determines that the input color difference signal is the double amplitude PAL60 system based on the detection result of the no-signal line detector 13, the gain of the analog amplitude adjuster 1 is “× 1/2 (one half)” 12 , The gain of the digital amplitude adjuster 4 is “× 1
(1: 1) "Set to 41. As a result, the video signal processing device of this embodiment is optimized for the color difference signals of the double amplitude PAL60 system.

As described above, by monitoring whether or not there are no signal lines every other scanning line, both the standard PAL color difference signal and the double amplitude PAL60 color difference signal are sent to the A / D converter. By keeping the input amplitude of
The color difference signals can be demodulated without deteriorating the quantization error in both the standard PAL system and the double amplitude PAL60 system.

(Embodiment 4) FIG. 4 is a block diagram showing a configuration of a video signal processing apparatus according to Embodiment 4 of the present invention, and corresponds to claims 1, 2, and 6.

In the circuit for demodulating a color difference signal from a PAL system video signal shown in FIG. 4, blocks having the same functions as those in FIGS. 1, 2 and 3 are designated by the same reference numerals, and the description thereof will be omitted. 2 is connected to the output side of the A / D converter 2 and the no-signal line detector 13 of FIG. 3, and the control device 6 controls the analog signal based on the information from the detectors 10 and 13. The amplitude adjuster 1 and the digital amplitude adjuster 4 are controlled.

Next, the operation of the video signal processing device having the above configuration will be described. The color difference signal immediately after demodulating the PAL color subcarrier is processed by the analog amplitude adjuster 1,
It is input to the A / D converter 2. The color difference signal converted into the digital signal by the A / D converter 2 is added by the adder 32 and the color difference signal of one horizontal period delayed by the delay line 31 of the adjacent scanning line adder 3 to adjust the digital amplitude. The change in the digital value subjected to the amplitude adjustment processing is corrected by the instrument 4.

The overrange detector 10 monitors the digital signal output from the A / D converter 2 and detects the overrange so that the voltage of the color difference signal is A / D converted by the A / D converter 2. It detects whether it is within the maximum possible amplitude.

In addition, the signalless line detector 13 is the scanning line 1
It is detected that the presence or absence of the color difference signal is alternately repeated for every book. The control device 6 controls the analog amplitude adjuster 1 and the digital amplitude adjuster 4 according to the result of the no-signal line detector 13.

Normally, the gain of the analog amplitude adjuster 1 is set to “× 1 (equal magnification)” 11 and the gain of the digital amplitude adjuster 4 is set to “× 1/2 (one half)” 42. . In this state, the color difference signal of the normal PAL system is optimized. Here, when the double amplitude PAL60 system signal is input, the overrange detector 10 detects that the amplitude is double that of the normal PAL system color difference signal, which is the first feature of the double amplitude PAL60 system. , Sends a signal to the controller 6.

The non-signal line detector 13 detects that the presence or absence of the color difference signal is alternately repeated every other scanning line, which is the second characteristic of the double amplitude PAL60 system, and the control device 6
Send a signal to. The control device 6 includes an overrange detector 10
If the input color difference signal is determined to be the double amplitude PAL60 method based on the detection result of the non-signal line detector 13 and the gain of the analog amplitude adjuster 1, the gain of the analog amplitude adjuster 1 is “× 1/2 (1/2)” 12, the digital amplitude adjustment The gain of the container 4 is set to “× 1 (equal magnification)” 41. As a result, the video signal processing device of this embodiment is optimized for the color difference signals of the double amplitude PAL60 system.

As described above, the detection accuracy of the double-amplitude PAL60 system can be improved by monitoring the amplitude of the input color difference signal and monitoring whether or not there are no signal lines at every other scanning line. Both the standard PAL system color difference signal and the double amplitude PAL60 system color difference signal can be used for both the standard PAL system and the double amplitude PAL60 system by making the input amplitude to the A / D converter constant. Also makes it possible to demodulate color difference signals without deteriorating the quantization error.

[0043]

As described above, in the video signal processing device of the present invention, in the circuit for demodulating the color difference signal from the PAL system video signal, the digital signal processing after the color subcarrier demodulation is performed by the standard PAL system signal. It is possible to support the double amplitude PAL60 system without degrading the resolution at the time of A / D conversion of the color difference signal at the time of input.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a video signal processing device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a video signal processing device according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a video signal processing device according to a third embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a video signal processing device according to a fourth embodiment of the present invention.

[Explanation of Codes] 1 ... Analog amplitude adjuster, 2 ... A / D converter, 3 ...
Adjacent scan line adder, 4 ... Digital amplitude adjuster, 5 ...
Voltage comparator, 6 ... Control device, 7 ... Normal reference voltage source, 8 ... Double amplitude reference voltage source, 9 ... Reference voltage switcher, 10 ... Overrange detector, 13 ... No signal line detector.

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04N 9/44-9/78

Claims (6)

(57) [Claims] 1. In a video signal processing device having a circuit for demodulating a color difference signal from a PAL television system video signal, a scanning line in which the amplitude of the color difference signal immediately after color subcarrier demodulation is twice that of a normal PAL system. And means for detecting a color difference signal of a special PAL television signal system in which scanning lines having an amplitude of 0 are alternately repeated,
A / D conversion means having a means for adjusting the amplitude so as to make maximum use of the resolution of D conversion, and a delayed color difference signal and a non-delayed color difference signal by a delay line for delaying the color difference signal for one horizontal period Information for calculating the color difference signal between the scanning lines, means for correcting a change in digital value after A / D conversion by adjustment for maximizing the resolution of the A / D conversion means, and information for the detection means. A video having a control means for controlling the A / D conversion means and the correction means on the basis of the above, and demodulating a color difference signal for both a standard PAL television signal and the special PAL television signal. Signal processing device. 2. In the means for A / D converting the color difference signals, the means for adjusting the amplitude of the input signal of the A / D converter is an amplifier or attenuator so as to maximize the resolution of the A / D converter. 2. The video signal processing device according to claim 1, wherein the video signal processing device is used. 3. The video according to claim 1, wherein an A / D converter having a unit for selecting a maximum amplitude that can be A / D converted is used as a unit for A / D converting the color difference signals. Signal processing device. 4. The special PAL television signal is detected by detecting that the input analog color difference signal is larger than a specified amplitude in the means for detecting the color difference signal of the special PAL television signal system. The video signal processing device according to claim 1, wherein the video signal processing device detects the fact. 5. The means for detecting the color difference signal of the special PAL television signal detects that the input analog color difference signal is a signal in which the presence or absence of the color difference signal is alternately repeated for every other scanning line. The video signal processing apparatus according to claim 1, wherein the video signal processing apparatus detects the special PAL television signal. 6. The means for detecting that the color difference signal is the special PAL television signal, the means for detecting that the input analog color difference signal according to claim 4 is twice the specified amplitude, and The accuracy of the means for detecting the special PAL television signal by using in combination the means for detecting that the input analog color difference signal is a signal in which the presence or absence of the color difference signal is alternately repeated for every other scanning line. The video signal processing device according to claim 1, wherein the video signal processing device is increased.