JPH0135554B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides quadrature modulation, in which one component signal modulates a main carrier and the other component signal consists of quadrature modulated subcarriers interleaved with sidebands of the main carrier in a portion of the spectrum. The present invention relates to a method and apparatus for separating component signals of a color television signal, and in particular, by using an adaptive comb filter, deterioration of image quality due to conventional separation loss and crosstalk between chromaticity and luminance occur. This makes it possible to perform chromaticity/luminance separation without any interference.

Conventionally, when designing transmission systems and signal formats for color television signals, in order to obtain the same image resolution, chromaticity information, which is as detailed as luminance information, and
In other words, it was thought that information on hue and color saturation was not necessary for human vision. In other words, human vision is extremely sensitive to changes in brightness as far as resolution is concerned, so generally the signal format of television signals is approximately 4M, such as 4.2MHz in the NTSC system.
Provides Hz frequency band and brightness information. On the other hand, for changes in hue or color saturation that are not accompanied by changes in brightness, human vision is saturated at a resolution of about 1/3 to 1/10 of the resolution caused by changes in brightness. For color signals, only a much narrower frequency band is provided than the frequency band provided for luminance information. For example, in the NTSC system, among the chromaticity signals, the signal has a frequency band of 1.3 MHz, whereas the frequency band of the Q signal is only 500 KHz. As a result of this frequency band limitation of the carrier color signal, the high frequency components, ie, the fine parts of the image, are colorless and chromaticity information is provided only over large areas.

Therefore, in order to prevent the dot structure of the television image from being noticeable, the color subcarrier frequency in the NTSC color television signal is
3579545MHz, the sidebands of the color subcarrier have a frequency that is an odd multiple of the line scanning frequency, and as a result, the sidebands of the carrier color signal are interleaved with the high frequency components of the luminance signal. There is a relationship between Thus, successive dots or pixels that result directly from the color subcarrier along one scan line are interleaved with dots or pixels that occur on the next scan line, and such successive dots or pixels resulting from the color subcarrier are interleaved with those resulting from the color subcarrier. The interleaved pattern was generally accepted as noticeable but not noticeable even when viewed as a black and white image.
One of the reasons that the dot pattern caused by the color subcarrier has been accepted as unnoticeable is that because the color subcarrier frequency is high, the dots appear very close to each other, and therefore the image screen If you move a little further away from the
There is a thing. That is, as mentioned above,
Since the dots on one scan line are interleaved with the dots on the next scan line, they become even more difficult to see if they are separated by a short distance. Another reason is that the image frequency band is relatively narrow in general home monochrome receivers, and therefore the above-mentioned dot pattern is difficult to see.
Furthermore, the chromaticity information in television images is mostly generated by color subcarriers, since color saturation is low and it is rare to see fully saturated color images such as the color bars of a test pattern. The intensity of the dot pattern is not greater than the luminance signal level of the surrounding area on which the dot pattern is superimposed. That is, the average value of color saturation in television images is approximately 20%. Therefore, the brightness of a dot due to the color subcarrier that appears on the scanning line is 20 times higher than the surrounding luminance signal level.
It rarely exceeds %.

In a color image displayed on a color television receiver, the interleaving relationship between the sideband of the color subcarrier at the upper end of the luminance signal spectrum and the high-frequency component luminance signal is such that the chroma signal level is 20% higher than the luminance signal level. For static color images with low color saturation, not exceeding %, the above works well. However, if there is a portion with a high chromaticity signal level, the signal level of the above-mentioned dot pattern exceeds the luminance signal level, and combined with the high gamma characteristics of the picture tube, the average luminance of the saturated portion will decrease. moving towards higher levels, so that, for example, a highly saturated red would once appear as pink on a picture tube screen.
Therefore, it is essential to remove the color subcarrier component from the luminance signal before supplying it to a display device for display.

To remove the above-mentioned color subcarrier components from the luminance signal, the conventional means generally used in color television receivers is to provide a band-rejection filter, usually consisting of an LC trap, in the path of the luminance signal. , the lower 3dB attenuation point is from 2.3MHz to
is to set it to 2.8MHz, and as a result,
The 150 nanosecond rise in the transient waveform of the input image signal had degraded to 250 to 300 nanoseconds. Therefore, in conventional color television receivers, there is a significant and continuous loss of image resolution, and the band-reject filter described above reduces the high resolution obtained when applying squared sine wave test pulses. Ringing occurred at the trailing edge of the speed transient waveform and pulse waveform.

Another problem encountered when using the imperfect chromaticity/luminance separation technique described above is that the high-frequency component luminance signal is demodulated in the chromaticity signal channel and is incorrectly treated as chromaticity information in the color demodulation circuit. That's true. As a result, when a simple bandpass filter was used to remove the luminance signal component from the chrominance signal channel, rapid luminance changes were followed by a rainbow pattern.

On the other hand, comb filters have long been known to perform chromatic/luminance separation from a composite spectrum in which luminance signals and chromaticity signals are in an interleaved relationship, with minimal deterioration in image quality, and have been known for some time.
In 1930, F. Gray, in U.S. Pat. It describes the use of comb filters that can be combined into relationships.

Then, with the advent of NTSC color television signals in which color subcarrier component signals are interleaved between high-frequency component luminance signals, gray filter technology was introduced to separate chromaticity and luminance information in color television receivers. It was suggested that. This gray filter technology is described by NW Parker in US Pat. No. 3,542,945, dated November 24, 1970. The band wave output signal of the composite image signal in which the chromaticity signal component is scattered in the high frequency component luminance signal and the other band wave output signal that has passed through the delay line and the phase inverter for one horizontal scanning period are combined by an adder. In particular, a kind of comb-shaped filter has been completed. Since the color subcarrier signal of the NTSC system is out of phase with each other by 180 degrees with respect to the horizontal synchronization pulse between two consecutive scanning lines, the color subcarrier signal components in the two types of band wave output signals mentioned above are are added to each other, but since the luminance signal components in two consecutive scanning lines are originally in phase, these luminance signal components are combined in antiphase with each other in the above-mentioned adder and canceled out. As a result, a comb-wave output chromaticity signal is obtained. In the Barker chromaticity/luminance separation circuit, the chromaticity signal separated as described above is added to the input composite color image signal consisting of the luminance signal component and the chromaticity signal component without phase inversion. The separated output luminance signal is obtained by performing antiphase cancellation of the luminance signal components. A comb-shaped filter with such a configuration by Parker is
It works well for static color images with low chroma signal levels. However, when there are sudden changes in the chromaticity signal in the vertical direction in a color television signal, or other dynamic changes in the chromaticity signal, the Parker comb filter described above may The above-mentioned dot pattern does not disappear, and aberrations and false images that deviate from the real image based on the instantaneous phase shift are clearly visible, and as a result, the high-frequency component luminance signal and chromaticity signal are The interleaving relationship between the two is lost.
Another drawback of the chromatic-luminance separation described above is that ringing and echoes occur in the transient waveform of the luminance signal due to imperfect operation of the one-horizontal scan period delay line, and such erroneous waveforms require a comb filter. It was also noticeable when the color saturation of the color image was low.

Furthermore, the usefulness of comb filters in the field of specialized television technology, such as correction of time base errors in the recording and playback of color image signals, is disclosed in U.S. Pat. and U.S. Pat. No. 3,764,739, dated October 9, 1973.

Also, SMPTE Journal, Vol.
86, No. 1, January 1977, pages 1 to 5, Arthur Kaiser describes how color proposed a color demodulation circuit in which the comb filter is replaced with an ordinary low-pass filter in the form of a trap circuit during the transition period of the color signal. Although Kaiser's adaptive comb filter was somewhat effective for its intended purpose, it was not very effective against diagonal chromaticity signal transient waveforms, and moreover, At the time, constructing the Kaiser circuit as shown in Figure 9 of the literature was extremely expensive;
It was necessary to use two broadband delay lines with a passband width of 4.2 MHz, which are still extremely expensive today. As a result, such Kaiser circuits are only used where the demands on the image signal warrant the high expense of performing chromatic-luminance separation, for example in television studios. Ta. Another drawback of Keizer's circuit is what is known as scalloping, which occurs when bright vertical lines are present during horizontal or diagonal transitions of color components. , occurs when two delay lines are used to completely remove the residual comb wave of the chromaticity signal in the vertical direction between two consecutive scanning lines.

An object of the present invention is to extract a quadrature-phase modulated subcarrier signal, which is superimposed in an interleaved manner on a part of the spectrum of the signal, from a signal obtained by modulating the main carrier wave in a quadrature-phase modulated color television signal using a comb filter. In addition to the separation, the purpose is to remove traces of the subcarrier signal from the main carrier signal by means of an additional comb wave.

Another object of the present invention is to eliminate dot patterns and false signal distortions from a color television signal much more effectively than previously by using a chrominance signal comb wave and a luminance signal adaptive comb wave.

Still another object of the present invention is to provide a comb-shaped filter,
The switching technique allows the use of an inexpensive one-horizontal scan period delay line to be used only when truly necessary, that is, when the color saturation exceeds a predetermined threshold level. ,
To enable a low-cost comb filter to be widely adopted.

Still another object of the present invention is to
The object of the present invention is to provide an adaptive comb wave system that similarly operates well for PAL color television signals.

Yet another object of the invention is to provide an adaptive comb wave system that is equally well suited for use in analog and digital circuits.

The adaptive comb filter used in the basic configuration of the present invention for separating chromaticity information and luminance information in a quadrature-phase modulated color television signal includes an input terminal for receiving a quadrature-phase modulated color television signal. will be established. The chromaticity separation circuit connected to the input terminal is provided with an output terminal for taking out an output signal delayed by one horizontal scanning period, and
Originally, an inexpensive narrow band delay line that transmits the band wave of the television signal is provided. A high-pass filter connected to the input terminal passes the high-frequency components of the television signal and supplies the filter to a subtracter having an input terminal connected to the output terminal of the delay line. Extract the waved chromaticity signal. The above-mentioned comb-shaped filter includes a threshold circuit connected to the output terminal of the chromaticity separation circuit to accept the separated chromaticity signal and extract only the portion of the separated chromaticity signal exceeding a predetermined threshold level. An adaptive brightness separation circuit is provided. A limiting amplifier connected to the output terminal of the threshold circuit is
Only when the portion taken out from the threshold circuit exceeds the predetermined threshold level is an amplitude limiting signal synchronized in phase with the portion taken out from the threshold circuit. The luminance separation circuit is also provided with a summing circuit having input terminals respectively connected to the output terminals of the threshold circuit and the limiting amplifier. A delay matching circuit connected to the input terminal applies a fixed delay to the television signal corresponding to a signal delay occurring between the input terminal of the comb filter and the output terminal of the adder circuit. The luminance subtraction circuit connected to the delay matching circuit and the addition circuit subtracts the output signal of the addition circuit from the output signal of the delay matching circuit, and the subtracted output signal is such that the chromaticity signal is equal to or less than the predetermined threshold value. This is an adaptive separated wave luminance signal in which the chromaticity signal is removed only when the level exceeds the level.

To remove residual chromaticity signal components from the luminance signal, if desired, the comb-wave luminance signal is applied to a complementary bandpass filter and a band removal filter, and the bandpass filter is passed through a switch to the adder circuit. Further improvements can be made by connecting to. The output signal of the chromaticity bandpass filter described above is applied to a rectifier whose output terminal is connected to one input terminal of a two-input control logic circuit that controls the switch. Further, the comb-wave chromaticity signal is supplied to another rectifier, and the output terminal of the rectifier is connected to the other input terminal of the two-input control logic circuit. Therefore, when a comb-waved chromaticity signal and a chromaticity signal residual component in an adaptive comb-waved luminance signal are simultaneously present, the control logic circuit opens the switch to The bandpass filter is disconnected so that only the bandpass filter is connected to the adder circuit.

Removal of the high-frequency component luminance signal from the chromaticity signal can also be further improved, if desired, by connecting two similarly constructed chromaticity separation circuits in series.

The chromaticity/luminance separation method according to the present invention separates the chromaticity signal from the luminance signal in a quadrature modulation color television signal by integrally multiplexing the color television signal at one horizontal scanning period. the high frequency waves of the color television signal and the simultaneous delay processes, and the high frequency waves of the color television signal;
A comb-wave output chromaticity signal is obtained by taking the difference between the high-frequency output signal and a high-frequency output signal which is delayed at the same time as the high frequency.

On the other hand, the luminance signal is adaptively separated and waved by removing only the components exceeding the predetermined threshold level of the above-mentioned comb wave output chromaticity signal through the following steps.

That is, the component of the comb-wave output chromaticity signal exceeding the predetermined threshold level is amplified, and then the amplitude is limited, the phase and polarity match the amplified output of the chromaticity signal component described above, and the comb-wave output chromaticity signal is amplified. A signal is extracted that appears only when the output chromaticity signal exceeds the threshold level. Then, the above-mentioned component exceeding the predetermined threshold level and the above-mentioned amplitude limiting signal corresponding to that component are added to produce a composite waveform signal that appears only when the comb wave output chromaticity signal exceeds the predetermined threshold level. Form. The color television signal is then delayed such that the signal delay corresponds to the formation of the composite waveform signal described above. The delay-matched color television signal is then subtracted from the composite waveform signal to obtain an adaptive comb-separated output luminance signal.

The chromaticity/luminance separation method according to the present invention described above includes:
In the following manner, a process is also provided for erasing from the luminance signal path residual components of the chromaticity signal that appear during the transition period of the chromaticity signal in the horizontal direction. That is,
The comb-wave output chromaticity signal is separated into a bandpass filter output and a band-rejection filter output, and the bandpass filter output is selectively output via a switch that is opened only during the horizontal transition period of the chromaticity signal. By adding the outputs of both filters while the chromaticity signal is intermittent, the above-mentioned residual component of the chromaticity signal is erased.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The objects, configurations, functions, and effects of the present invention will be described in detail below with reference to the drawings.

First, the basic structure of an adaptive comb filter 10 according to the present invention is shown in FIG. In the figure, a video input terminal 12 is supplied with a quadrature modulated color television signal from a signal source, such as a video detector (not shown) in a color television receiver. The color television signal from image input terminal 12 is applied to delay line 14 to provide a delay of one horizontal scan period or 63.556 microseconds. This delay line 14 also functions as a bandpass filter with cutoff frequencies of approximately 2.5 MHz and approximately 4.7 MHz. To configure such a delay line 14,
Ultrasonic glass delay lines, such as those used in PAL or SECAM color television receivers, are suitable because they are low cost and suitable for mass production.

The one-scan line delayed band wave output signal from the delay line 14 described above is supplied to the subtraction circuit 16, and at the same time, the composite color television signal from the input terminal 12 is sequentially supplied to the delay adjustment circuit 18 and the high-pass filter 20. As a second input signal to the subtraction circuit 16, a high frequency output signal is formed which is not delayed by one scan line period but has the delay due to the wave process matched. Therefore, the above-mentioned two input signals supplied to the subtraction circuit 16 are separated by one scanning line on the image plane.

The delay adjustment circuit 18 adjusts the timing at which the input color television signal passes, so that the two input signals supplied to the subtraction circuit 16 have timings separated by exactly one scanning line, as described above. Also, the high pass filter 20 removes the low frequency component luminance signal from the input color television signal.

The subtraction circuit 16 described above performs subtraction between the two input signals from the delay line 14 and the high-pass filter 20, and for the chroma signal component in the input composite color television signal, the two input signals are
Since they are out of phase with each other, they are combined additively, while for the luminance signal component, the two input signals are in phase with each other, so they are canceled out. In this way, the output line 22 from the subtraction circuit 16 receives a comb-wave output chromaticity signal in which the stationary luminance signal component is canceled out and the chromaticity signal component is added. Ru.

As mentioned above, when a low-cost ultrasonic delay line is used in the chromaticity signal path, the effect of the ultrasonic delay is incomplete, so the cancellation and removal of the luminance signal component described above is not complete. It is not carried out in As a result, significant ringing of the luminance signal following transient changes in the chroma signal appears in the path of the chroma signal, thus distorting the comb-wave output chroma signal described above from the input composite color television signal. If the subtraction is performed as is, significant ringing will also appear in the path of the resulting comb-wave output luminance signal. In the past, to avoid this problem, high-performance but extremely expensive delay modules were used in place of the above-mentioned low-cost delay lines. In contrast, the present invention solves the above-mentioned problem of ringing without using expensive high-performance delay elements.

That is, the comb wave output chromaticity signal appearing on the output line 22 described above is supplied to the threshold amplification circuit 24,
Of the comb wave output chromaticity signal, only the portion exceeding a predetermined threshold amplitude set by the threshold amplification circuit 24 is amplified. An output line 26 from the threshold amplifier circuit 24 is connected to a limiting amplifier 28 and also to one input terminal of an adder circuit 30 . Each time a portion of the comb wave output chromaticity signal exceeding a predetermined threshold level is extracted from the threshold circuit 24, an amplitude limited output signal having the same phase and polarity as that portion is extracted from the limiting amplifier 28. . The output line 29 from the limiting amplifier 28 is connected to the other input terminal of the summing circuit 30. The summing circuit 30 is configured to generate a comb signal exceeding a predetermined threshold level obtained when the square wave pulse from the limiting amplifier 28 and the comb wave output chromaticity signal of the portion exceeding the predetermined threshold level are taken out from the threshold circuit 24. It has a function of combining the wave output chromaticity signal. Therefore, FIG. 2a appearing on the output line 22
The luminance signal residual component present in the comb-wave output chromaticity signal having the waveform A of FIG. Since none of those comb-wave output chromaticity signals exceed the predetermined threshold level, they disappear.On the other hand, the comb-wave output chromaticity signals that exceed the predetermined threshold level It is removed by the action of amplifier 28 and summing circuit 30.

Further, the composite color television signal from the input terminal 12 is supplied to the chromaticity subtracting circuit 34 via the delay matching circuit 32, and the addition output signal from the adding circuit 30 is also supplied to the chromaticity subtracting circuit 34. subtracted from the composite color television signal from delay matching circuit 32. This chromaticity subtraction circuit 34
is performed in the same way as in the threshold circuit 24, each time the chromaticity signal exceeds a predetermined threshold level.
It has a function of canceling out and removing the portion exceeding a predetermined threshold level from the chromaticity signal. Also,
The delay matching circuit 32 delays the composite color television signal from the input terminal 12 and combines it with the addition output signal from the addition circuit 30 by the chromaticity subtraction circuit 34 while maintaining an appropriate time relationship. Make it. Therefore, an adaptive comb wave output luminance signal is obtained at the output terminal 36 of the chromaticity subtraction circuit 34. In the adaptive comb filter shown in FIG. 1, the amplitude of the chromaticity signal is preferably approximately
The comb filter 10 has a function of activating the luminance separation comb filter only when a predetermined threshold level set in units of 10 IRE is exceeded, and the comb filter 10 having such a function allows the chromaticity signal and the luminance signal to be interleaved. The prerequisite is the recognition that human vision can only perceive dot patterns caused by the It is said that Therefore, in the chromaticity/luminance separation system shown in Figure 1, if the level of the dot pattern is between 0 and about 10 IRE units,
The threshold circuit 24 does not pass the chromaticity signal, and further,
Since dot patterns with a level of 10 IRE units or less are not perceived, the color image displayed at that time can satisfy human vision, and the residual signal components remaining in the chromaticity signal path are It does not deteriorate the waveform.

To explain the operation of the chromaticity/luminance separation system shown in Fig. 1 with respect to the signal waveform shown in Fig. 2, one cycle of the comb-wave output chromaticity information signal is as shown in waveform A in Fig. 2a, and this waveform A comb-wave output chromaticity signal appears at the output terminal 26 of the threshold circuit 24.
Waveform B shown in FIG. 2b represents a waveform obtained by removing the portion below a predetermined threshold level from the comb-wave output chromaticity signal of waveform A. Therefore, only the peak portion of the sine wave of waveform A is the waveform of waveform B. remains, but its phase is the same as waveform A.
Furthermore, the output signal of the limiting amplifier 28 is as shown in FIG.
The waveform C is as shown in the figure, and this waveform C is two square waves having the same phase and the same polarity as the waveform B, but opposite polarities. Further, the addition output signal from the addition circuit 30 has a waveform D which is a combination of waveform B and waveform C, as shown in FIG. 2d.
is doing.

Next, the operation of the comb filter having the configuration shown in FIG. 1 can be better understood by analyzing the characteristic curves shown in FIG. 2 e, f, and g.
That is, in each characteristic curve shown in FIG. 2e and f, the horizontal axis represents the level of the input chromaticity signal amplitude, that is, the level of the chromaticity signal amplitude appearing on the output line 22 of the subtraction circuit 16, and the vertical axis represents the level of the chromaticity signal amplitude appearing on the output line 22 of the subtraction circuit 16. shows the level of the output chromaticity signal amplitude. In the characteristic curve shown in Figure 2e, the diagonal characteristic curve A indicated by a solid line corresponds to waveform A indicating that the amplitude of the output chromaticity signal is completely proportional to the amplitude of the input chromaticity signal. A diagonal characteristic curve B indicated by a broken line indicates that the amplitude of the output chromaticity signal is at a predetermined threshold level T.
The output signal of the limiting amplifier 28 corresponds to waveform B which shows that the amplitude of the input chromaticity signal is proportional to the amplitude of the input chromaticity signal in the part exceeding
It immediately rises at the threshold level T, and even if the amplitude of the input chromaticity signal exceeds the threshold level T, a constant output level is maintained.

Next, in the characteristic curve shown in Fig. 2 f,
A characteristic curve of a composite signal obtained by adding a luminance signal and a chromaticity signal is shown by a broken line E, and a characteristic curve of an added output signal from the adding circuit 30 is shown by a solid line D. When it exceeds, the amplitude of the added output signal is proportional to the amplitude of the input chromaticity signal,
When the amplitude of the input chromaticity signal does not reach the predetermined threshold level, this indicates that the amplitude of the addition output signal is zero.

Next, the operation of the chromaticity subtraction circuit 34 is shown in FIG.
This can be well understood by referring to the characteristic curve shown in Figure 2. In the characteristic curve shown, the vertical axis represents the amplitude of the residual chromaticity signal component appearing in the path of the comb-wave output luminance signal, and the amplitude of the input chromaticity signal The horizontal axis represents the amplitude, and the ideal characteristic curve of the subtracted output signal of the chromaticity subtraction circuit 34 is shown by the broken line F, but the actual characteristic curve is This is as shown by the wavy solid line F, which shows that an output chromaticity signal with an extremely small amplitude appears even with respect to the chromaticity signal. In addition, chromaticity signal delay 1
Ringing in the luminance signal due to malfunction of the scanline period delay line is not visually perceptible.

In the above description, a case has been described in which the above-described comb filter 10 according to the present invention is applied to separation of a chromaticity signal and a luminance signal in an NTSC color television signal. The signal delay time at 2
By simply extending the scanning line period, it can be easily applied to chromaticity/luminance separation in PAL color television signals. Furthermore, as will be readily apparent to those skilled in the art, each component of the comb filter according to the invention, which is described in this detailed description as using analog technology, can also be easily constructed using digital technology and digital circuitry. can do.

Now, the threshold circuit 24 and the limiting amplifier 28 mentioned above
And an example of the specific circuit configuration of the adder circuit 30 is shown in the third section.
To explain with reference to the figure, in the illustrated circuit configuration, the comb wave output chromaticity signal described above is transmitted to the output line 2.
2 as an input signal to the threshold circuit 24. The output line 22 is connected to a block capacitor 40.
and a timing resistor 42 in order to the base of a phase inverting transistor 44 . +
A series base bias network consisting of a resistor 41 connected between a 12 volt voltage supply line 46 and a ground resistor 43 is connected to the junction of blocking capacitor 40 and resistor 42. The phase inverting transistor 44 made of a PNP transistor has its emitter connected to the +12 volt voltage power supply line 46 via an emitter resistor 48, and its collector connected via a collector resistor 52 having the same resistance value as the emitter resistor 48. -12 volt voltage power supply line 50,
Therefore, the amplitudes of mutually opposite phase signals appearing at the collector and emitter of the phase inversion transistor 44 are approximately equal. The emitter output signal of the phase inversion transistor is connected to the timing resistor 5.
6 through the first emitter follower transistor 54
It is supplied to the base of The first emitter follower NPN transistor 54 connects its collector directly to the +12 volt voltage supply line 46 and
The emitter is grounded via a load resistor 58.
The output signal from the first emitter follower transistor 54 is routed through a blocking capacitor 60 and a grounded load/bias resistor 62 to the base of the first transistor 64 in a monolithically integrated transistor circuit 66 via a pin terminal 6. It is supplied to On the other hand, the phase inversion transistor 44
The collector of is connected to the base of the second emitter follower transistor 68 via a timing resistor 70. The second emitter follower transistor 68 has its collector directly grounded and
The emitter is connected to the base of a second transistor 78 in the integrated transistor circuit 66 via a blocking capacitor 74 and a timing resistor 76 in sequence, and a grounded base bias resistor 80 of the second transistor 78 is connected to the blocking capacitor 70 and the timing resistor. It is connected to the connection point with 76.

On the other hand, an integrated transistor circuit 66, preferably a CA3046 type integrated circuit manufactured by RCA, is provided with four transistors 64, 78, 82 and 84.
2 and 84 constitute two differential amplifiers in combination, and transistors 78 and 82
The output terminal with the emitters of the transistors 64 and 68 connected together is connected to the pin terminal 3 to form one differential amplifier, and the output terminal with the emitters of the transistors 64 and 68 connected together is connected to the pin terminals 11 and 8. The other differential amplifier is configured. On the other hand, the collectors of the transistor pair 78 and 82 are connected to each other and connected to the pin terminals 1 and 5, and
The collectors of transistor pairs 64, 84 are connected together and to pin terminals 11, 8, and the collectors of all four transistors in integrated transistor circuit 66 are connected to +12 volt voltage supply line 46.
are connected in a straight line. In addition, the transistor 82
and 84 are connected together to pin terminals 4 and 9 of integrated transistor circuit 66 and are further connected to +12 volt voltage supply line 46 through resistor 86.
and is grounded via a resistor 88. The resistance ratio between resistors 86 and 88 supplies a constant voltage to the bases of transistors 82 and 84, thereby setting the lower threshold level at which transistors 64 and 78 begin linear amplification. It provides functionality. Note that the use of a single monolithic integrated circuit 66 ensures that the four transistors have nearly identical forward transfer characteristics.

Of the two differential amplifiers mentioned above, the output signal from one of the differential amplifiers consisting of transistors 78 and 82 is taken out from the emitter connection point connected to the pin terminal 3, and is passed through a timing resistor 90 to the output signal of the transistor 92. It is supplied to the base. A load resistor 94 is connected from the pin terminal 3 of the integrated transistor circuit 66 to the -12 volt voltage power supply line 50. The emitter of transistor 92 is also connected to -12 volt voltage power supply line 50 via resistor 96, and the frequency compensation network consisting of capacitor 98 and resistor 100 is also connected to transistor 92.
It is connected from the emitter to the ground point. Further, the collector of transistor 92 is connected to the +12 volt voltage power supply line 46 via a load resistor 102 and to the base of an emitter follower transistor 106 via a timing resistor 104. transistor 10
6 connects the collector directly to the +12 volt voltage power line 4
6, and its collector is connected to the emitter of another transistor 110 via a resistor 108. Note that transistors 92 and 106 act as a phase inverter.

The emitter of transistor 110 is connected to resistor 112.
The emitter of the transistor 110 is connected to the -12 volt voltage power supply line 50 via the -12 volt power supply line 50, and the emitter of the transistor 110 is connected to the pin terminals 10, 7 from the emitter connection point of the second transistor pair 64, 84 in the integrated transistor circuit 66. A extracted output signal is also provided, and the output signal is applied to the emitter of transistor 110 via resistor 114. In addition,
This transistor 110 serves to combine the output signals from the two differential amplifiers in integrated transistor circuit 66. Further, the transistor pair 64 and 84 are connected to each other, and the resistor 11
6, it is also connected to a -12 volt voltage power supply line 50. Furthermore, the transistor 110 has a base almost directly grounded via a low resistance oscillation suppression resistor 118, and a collector connected to the load resistor 12.
0 to the +12 volt voltage power supply line 46;
Furthermore, it is also connected to the base of an emitter follower output transistor 124 via a delay matching resistor 122. Its emitter follower output transistor 1
24 connects the collector directly to the +12 volt voltage power supply line 46, and connects the emitter to the load resistor 1.
It is grounded via 26. The output signal from the threshold value setting circuit 24 configured as described above is taken out through an output line 26 directly connected to the emitter of the emitter follower output transistor 124.

As shown in FIG. 1, output line 26 from threshold circuit 24 is connected to an input terminal of limiting amplifier 28 and also to one input terminal of summing circuit 30. As shown in FIG. That is, in the circuit configuration shown in FIG. 3, the output line 26 is connected to the base of a transistor 132 in a monolithic integrated transistor circuit 134 via a block capacitor 128 and a timing resistor 130 in order. Transistor circuit 13
4 has two additional transistors 136 and 1
38 are provided. Note that a grounding resistor 140 and a resistor 142 connected to the +12 volt voltage power supply line 46
A base bias network consisting of the following is connected to the junction of block capacitor 128 and timing resistor 130. The aforementioned transistor 132 is +
It has a collector connected directly to the 12 volt voltage power supply line 46 and an emitter connected in parallel to the emitter of transistor 136, and the two parallel connected emitters are connected to transistor 138 which acts as a common current source. is connected to the collector.

The transistor 138 has its emitter connected to a resistor 1
44 to the -12 volt voltage power supply line, and at its base, a ground resistor 146 and -
Biasing is provided by connecting a resistor network consisting of a resistor 148 connected to the 12 volt voltage supply line 50. The base of transistor 138 is decoupled by a bypass capacitor 150 to ground. The transistor 136 also has a base connected to a low resistance 15 for suppressing oscillation.
2 to ground, and the collector is connected to a +12 volt voltage power supply line 46 via a load resistor 154. The monolithic integrated transistor circuit 134 is preferably manufactured by RCA Corporation.
Constructed using CA3018 type or CA3046 type integrated circuit.

The output line 29 from the limiting amplifier 28 configured as described above is connected from the collector of the transistor 136 to the blocking capacitor 156 and the balancing resistor 1.
58 to the emitter of transistor 160 to adder circuit 30. Also,
The output line 26 from the threshold circuit 24 also connects to the limiting amplifier 2.
It is connected to the emitter of a transistor 160 through a block capacitor 161 and a balance resistor 162, which correspond symmetrically to a block capacitor 156 and a balance resistor 158 connected in series to the output line 29 from the transistor 8.

Transistor 160 of adder circuit 30 connects its emitter to -12 volt voltage power supply line 5 through resistor 164.
0 and connect the base to low feedback resistance 1.
65, and the collector is
+12 volt voltage power line 4 through load resistor 166
6 and to the base of the emitter follower output transistor 168 via a low resistor 170 for isolation and delay matching. The emitter follower output transistor 168 has its collector connected directly to the +12 volt voltage power supply line 46 and to ground via a fixed resistor 172 in series with a variable resistor 174. , a block capacitor 176, and a resistor 178 in order to output a variable amplitude addition output signal to the output line 31. Its output line 31
is connected to the subtraction input terminal of the chromaticity subtraction circuit 34, as described above with respect to FIG.

Here, referring again to FIG. 1, the delay time of the delay matching circuit 32, preferably about 180 nanoseconds, is from the video input terminal 12 to the adder circuit 30.
This corresponds to the delay in signal transmission in the signal path leading to.

Next, moving on to the explanation of FIG. 4, the additional circuit components shown in the figure are those to be connected to the comb filter 10 shown in FIG. In particular, in this luminance signal path, interleaving of the chromaticity signal with respect to the high frequency component of the luminance signal is not completely performed. Such conditions typically arise due to changes in chromaticity in the vertical direction of the image. Additional circuitry 180 shown in FIG.
does not reduce the resolution of the luminance signal except when the dot pattern appears excessively.
Further, the circuit system 180 shown in the fourth figure has two different operating characteristics in relation to the comb filter 10 shown in the first figure. The first is that no dot pattern is observed when there is no transient change in chromaticity in the vertical direction of the image, and a luminance signal with a sufficiently wide band can be obtained between the input and output.
Second, during a period in which a transient change in chromaticity occurs in the vertical direction of the image, a transient signal near the color subcarrier frequency appears in the luminance signal path, and a transient signal also appears in the chromaticity signal path. When the signal appears, the signal bandwidth in this circuitry 180 momentarily narrows, separating the chroma signal from the luminance signal channel. However, this second operating state rarely occurs, and even when it does occur, it is usually beguiled by vertical transient changes in luminance that occur simultaneously with changes in chromaticity. Furthermore, when the boundaries between adjacent images are nearly horizontal, the limited signal bandwidth is not noticeable to the human eye, so high resolution is not necessary from the perspective of human vision. do not have.

Thus, the circuit system 180 shown in the fourth diagram is supplied with a comb-wave input luminance signal by connecting it to the comb-wave luminance signal output line 36 of the comb-shaped filter 10 shown in the first diagram. By connecting to the comb-wave chromaticity signal output line 22 of the comb-wave filter 10 shown in FIG. 1, a comb-wave input chromaticity signal is supplied. The comb input luminance signal from output line 36 is provided to two complementary filters: a bandpass filter 182 and a bandreject filter 184. The bandpass filter 182 has a bandpass characteristic suitable for passing chrominance subcarrier information and luminance information near the chrominance subcarrier frequency, while the band rejection filter 184 removes the chromaticity signal band. At the same time,
The adder circuit 186 passes the low frequency component of the luminance signal.
supply to. Moreover, the band pass filter 182 is
It has an output line 188 connected to a rectifier 190 and a switch 192. The rectifier 190 is
It has an output terminal connected to a switch control logic circuit 194. On the other hand, the comb-wave input chromaticity signal from the output line 22 is rectified by a rectifier 196 and then supplied to the switch control logic circuit 194 described above. An output line 198 from the switch control logic circuit 194 is connected to and drives the switch 192 described above.

The operation of the circuit system 180 shown in FIG. 4 can be better understood by referring to each signal waveform shown in FIG. That is, the comb filter 10 shown in the first diagram
The input image signal including the color subcarrier signal appearing at the video input terminal 12 has the signal waveform shown in FIG. 5a. The comb-wave input chromaticity signal supplied from the output line 22 to the input terminal of the rectifier 196 has a signal waveform A shown in FIG. 5b. Furthermore, the comb-wave input luminance signal that appears on the output line 36 and erases the chromaticity signal of 10 IRE units or more but leaves the chromaticity signal of 10 IRE unit or less remains.
It has a signal waveform F shown in Figure c. Furthermore, the wave output signal of the bandpass filter 182 is as shown in FIG.
When the wave output signal is rectified by the rectifier 190, it becomes a pulse signal with the signal waveform H shown in FIG. 5e. The comb-wave input chromaticity signal rectified by the rectifier 196 becomes a square-wave pulse signal train having a signal waveform J shown in FIG. 5f. Furthermore, the logic control signal that drives the switch 192 is a pulse signal with a signal waveform K shown in FIG.
When combined with the wave output signal from 4, a signal is obtained in which the vicinity of the color subcarrier frequency has a constant DC potential as shown in the signal waveform L shown in FIG. 5h. In the circuit system 180 shown in FIG. 4 as described above, a composite video signal from which chromaticity information has been completely removed appears at the luminance signal output terminal 200, as shown in the signal waveform N shown in FIG. 5i.

The switch control logic circuit 194 described above acts as an AND gate and connects the rectifiers 190 and 19.
Each time a rectified output signal exceeding the gate threshold level of the AND gate 194 is simultaneously supplied from 6 to 6, the switch 192 is driven and operated.
Since the path of the chromaticity signal from 2 to the adder 186 via the switch 192 is opened, the signal band of the luminance signal is limited during the period when the vertical chromaticity of the image is changing. Band removal filter 184
The band characteristics are as follows. This applies to each signal waveform shown in FIG. 5, especially the signal waveforms G, H, J, K, and L.
and N.

Next, as shown in FIG. 6, the separation of chromaticity signals by comb waves can be further improved by using the comb filters 10 described above with reference to FIG. 1 in duplicate. That is, in the circuit system 210 shown in FIG. 6, a composite video signal is supplied to the video input terminal 212, and the video input terminal 212 is
a first delay line 2 having a delay time of one scan line period;
It is connected to 14. The output terminal of the first delay line 214 is connected to a first subtractor 216 . The composite video signal from the video input terminal 212 is
The first subtractor 216 is also supplied by a path sequentially passing through the first delay adjustment circuit 218 and the first high-pass filter 220. Therefore, in the first subtractor 216, The difference between the high-pass wave output video signal and the high-pass delayed output video signal is obtained and is supplied as the output signal of the first stage comb filter to the second stage comb filter configured in the same manner as the first stage. be done. The second stage comb filter includes a second delay line 222 and a second subtractor 22.
4. A second delay adjustment circuit and a second high-pass filter 228 are provided, and the output signal of the second subtracter 224, which is a comb-shaped chromaticity signal, is taken out from the output terminal 230. It should be understood that the above-described circuit system 210 shown in FIG. 6 is similar to the chromaticity signal comb wave circuit described above for the comb filter 10 shown in FIG. The luminance signal component remaining in the luminance signal is
It differs from the comb-wave circuit shown in FIG. 1 in that the comb-wave of the chromaticity signal is performed more effectively because it is more effectively canceled by the double comb-wave process.

In the above, the gist of the chromaticity/luminance separation device and method of the present invention has been described, and an embodiment in which it is applied to processing a color television signal has been explained with reference to the drawings. However, the device and method of the present invention are not limited to this embodiment. In the design of various telecommunications equipment and telecommunications systems, communication equipment in which a quadrature-phase modulated subcarrier signal also exists in an interleaved relationship between the modulated sidebands of the main carrier wave in a part of the signal band of the main carrier wave. Those skilled in the art will readily understand that the present invention can be similarly applied to any communication system. That is, nothing should be construed as limiting the scope of the present invention to processing only color television signals.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of the basic configuration of the chromaticity/luminance separation device according to the present invention, and FIGS. Figure 3 is a circuit diagram showing an example of a specific configuration of a part of the same.
The figure is a block diagram showing a configuration example of a part of the chromaticity/luminance separation device according to the present invention added to the basic configuration shown in Figure 1, and Figures 5a to 5i are signal waveforms respectively showing signal waveforms of each part. 6 are block diagrams showing other examples of the basic configuration of the chromaticity/luminance separation device according to the present invention. 14...Band wave delay circuit, 16...Subtraction circuit, 18...Delay adjustment circuit, 20...High pass filter, 24...Threshold circuit, 28...Limiting amplifier, 30...Addition circuit, 32... delay matching circuit,
34... Chromaticity subtraction circuit, 66, 134... Circuit system, 182... Band pass filter, 184... Band removal filter, 186... Adder, 190, 1
96... Rectifier, 192... Switch, 214,
222...1 scan line period delay line, 216, 224
...Subtractor, 218, 226...Delay adjustment circuit,
220, 228...High pass filter.

Claims (1)

[Scope of Claims] 1. A chromaticity/luminance separation device using a comb filter for a quadrature modulated color television signal having chromaticity sidebands and luminance sidebands interleaved with each other, wherein the quadrature modulated color television signal is a filter input terminal for supplying a filter input terminal; a bandpass filtering delay line means connected to the filter input terminal for bandpass filtering and delaying the quadrature modulated color television signal by one horizontal scan period; high pass filtering means for passing high frequency components of a phase modulated color television signal, first subtractor means connected to said bandpass delay means and said high pass filtering means to form a chromatic separation difference output signal; Filtering of the bandpass delay line means is connected between a filter input terminal and the high pass filter means to time the high frequency component of the quadrature modulated color television signal to reach the first subtractor means. chromaticity separation circuit means having delay adjustment means for adjusting the time relationship to the delayed output signal; Threshold circuit means for extracting only the portion exceeding the threshold; connected to the threshold circuit means to extract a square wave signal having a constant output level phase-locked to the portion only when the portion exceeds the predetermined threshold; limiting amplifier means, summing circuit means for summing the respective outputs of said threshold circuit means and said limiting amplifier means; connected to said filter input terminal and said summing circuit means to extract a signal from said quadrature modulated color television signal; a second subtracting the summation output signal to form a luminance separation difference output signal;
subtractor means connected between said filter input terminal and said second subtracter means so that said quadrature modulated color television signal is applied to the output terminals of said second subtractor means and said adder circuit means, respectively. adaptive luminance separation circuit means having delay matching means for equalizing arrival times, the addition output signal of the addition circuit means being substantially zero when the chromaticity separation difference output signal does not exceed the predetermined threshold; , wherein the constant output level of the square wave signal is selected to be approximately equal to the chromatic separation difference output signal when the chromaticity separation difference output signal exceeds the predetermined threshold value. A chromaticity/luminance separation device using a comb filter for modulated color television signals. 2. The chromaticity/luminance separation device according to claim 1, further comprising another chromaticity separation circuit means configured in substantially the same manner as the chromaticity separation circuit means and connected in series. A chromaticity/luminance separation device using a comb filter for phase modulation color television signals. 3. In the chromaticity/luminance separation device according to claim 1, band-rejection filtering means is connected to the output terminal of the second subtracter means and removes residual chromaticity components in the luminance separation difference output signal. and bandpass filtering means connected to the output terminal of the second subtractor means and configured substantially complementary to the bandpass filtering means so as to pass the residual chromaticity component in the luminance separation difference output signal. , a switch means connected to the bandpass filtering means to selectively pass the residual chromaticity component according to a control signal, and a switch means connected to the bandpass filtering means and the switch means to combine signals from the means. a first rectifier means connected to the output terminal of said bandpass filtering means to form a first rectified output signal; a second rectifier means forming a rectified output signal of and an input terminal connected to said first and said second rectifier means and said first and said second rectified output signal are logically identical; a logic gate circuit having an output terminal connected to said switch means for applying said control signal, said switch means opening when said first and said second rectified output signals are formed simultaneously. additional chromaticity separation by decoupling said bandpass filtering means from said adder means and supplying the signal passed through said bandpass filtering means to the output terminal of said other chromaticity separation circuit means. Chromatic luminance separation using a comb filter for a quadrature modulated color television signal, characterized in that second additional adaptive luminance separation circuit means are provided for filtering the luminance output signal and filtering the luminance output signal. Device. 4. In the chromaticity/luminance separation device according to claim 1, the bandpass filter delay line means
A chromaticity/luminance separation device using a comb-shaped filter for a quadrature phase modulation color television signal, characterized in that the quadrature phase modulation color television signal of the PAL color television system is delayed by two horizontal scanning periods. 5. In a chromaticity/luminance separation device using a comb filter for a quadrature modulated color television signal having mutually interleaved chromaticity sidebands and luminance sidebands, the comb filter is provided with a chromaticity/luminance separation device for a quadrature modulated color television signal having interleaved chrominance sidebands and luminance sidebands. chromaticity component separation means for separating the chromaticity component signal through comb filtering; and chromaticity component threshold means for passing the chromaticity component signal when the chromaticity component signal exceeds a predetermined threshold amplitude; The quadrature modulated color television signal is extracted when the chroma component signal does not exceed the threshold amplitude, and the chroma component signal is extracted from the quadrature modulated color television signal when the chroma component signal exceeds the threshold amplitude. 1. A chromaticity/luminance separation device using a comb-shaped filter for quadrature phase modulation color television signals, characterized in that a comb-filtered luminance signal is extracted by subtracting .