JPS6137830B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a color signal processing device used in a color television receiver or the like, which is capable of receiving television signals of different formats with a single device. [Technical Background of the Invention] There are three color television signal systems currently used in the world: NTSC, PAL, and SECAM. Each of these systems was uniquely adopted by each country or territory, but with the progress of color television broadcasting using space satellites and the spread of video tape recorders, the signals of these different systems have changed. There is an increasing demand for so-called multi-system color television receivers that can receive images with a single color television receiver. Conventional multi-system color television receivers are
In order to reproduce and process the signals of each system, each television signal processing circuit suitable for each system is independently provided. For this reason, conventional multi-system color television receivers have problems such as an increase in price, an increase in power consumption, and a decrease in reliability in proportion to the increase in the number of component parts. In order to solve the above-mentioned problems, multi-system color television receivers have been developed that reduce the number of parts by increasing the number of circuits that can be used in common with each system when the signal systems are similar. . This multi-system color television receiver is
It can receive images in NTSC and PAL formats. Here, the unique parts of NTSC and PAL color television receivers are
The explanation will be given with reference to FIGS. FIG. 1 shows a color signal processing circuit of an NTSC color television receiver. 11 is a chroma signal input terminal, and 12 is a band amplification circuit. The band amplification circuit 12 includes an automatic gain control circuit (ACC) and a burst gate circuit.
This is a circuit that detects level fluctuations in the input signal and automatically controls the output so that it is always at a constant level.
The burst gate circuit is a circuit for separating a color signal component and a burst signal from an input signal. The chroma signal separated by the band amplification circuit 12 is
The signal is input to the color control circuit 14 via the transmission line 13 and amplified according to the user's adjustment. The output chroma signal from the color control circuit 14 is sent to a (B-Y) demodulator 15 and a (R-Y) demodulator 17.
is input. On the other hand, the burst signal separated by the band amplification circuit 12 is input to the hue control circuit 19 via the transmission line 18. Hue control circuit 19
The receiver has a function of correcting hue errors caused by influence of the television signal on the transmission path on the receiver side, and adjustments for the correction are made by the user. The burst signal whose phase has been adjusted in the hue control circuit 19 is input to a color synchronization circuit 21 via a transmission line 20. The color synchronization circuit 21 includes a demodulation reference subcarrier generator for generating subcarriers necessary for demodulating color signals, and a killer detector for determining whether color broadcasting is monochrome broadcasting. The output of the killer detector is supplied to the color control circuit 14 or the demodulator, and the circuit function can be stopped so as not to generate color noise during monochrome broadcasting. The reference subcarrier generator has an automatic phase control function that accurately follows the phase of the input burst signal, generates subcarriers for demodulation based on the phase of the burst signal, and transmits each subcarrier through transmission lines 22 and 23. (B-Y) demodulator 15,
(RY) is supplied to the demodulator 17. Figure 2 shows the color signal processing circuit of a PAL color television receiver. Components having the same functions as those of the circuit shown in FIG. 1 will be described with the same reference numerals. The chroma signal output from the color control circuit 14 is input to a 1H (one horizontal period) delay device 31, and is also inputted via an attenuator 32.
The signal is input to the PAL matrix circuit 33. The output of the 1H delay device 31 is also added to this PAL matrix circuit 33. In the PAL matrix circuit 33, matrix processing is performed on the 1H delayed signal of the chroma signal and the undelayed signal, and the chroma signal is separated into a (B-Y) component and a (R-Y) component. -Y) demodulator 15 and (RY) demodulator 17. By the way, in the PAL system, the demodulation axis of the (RY) component is inverted by 180 degrees every horizontal period and transmitted. This is a feature of the PAL system, and when the PAL matrix circuit 33 performs vector synthesis of the signal from one horizontal period before and the direct signal, the influence of subcarrier phase distortion on the demodulated signal is reduced.
Since the PAL system is less susceptible to phase distortion in the transmission path, a hue control circuit is not required, and the burst signal separated by the band amplifier circuit 12 is directly input to the color synchronization circuit 21 to generate a reference subcarrier. used for purposes. Color synchronization circuit 21
The subcarrier for (B-Y) demodulation obtained in (R
-Y) Input to demodulator 15. Also, (R-
Y) The subcarrier for demodulation is input to the pulse switch circuit 34 which is driven by a horizontal retrace pulse and obtains an inversion operation every horizontal period, and the phase is adjusted. (R
-Y) Input to demodulator 17. Further, the inverting operation of the pulse switch circuit 34 is performed with respect to the transmission signal (R-
Y) The color subcarrier for demodulation is controlled to have the correct phase. The pulse switch circuit 34 is
The internal flip-flop circuit output is inverted or non-inverted by the horizontal retrace pulse. In the above-mentioned color signal processing circuit dedicated to the NTSC system and the PAL system, a common circuit that can be used in both systems with common functions is configured as shown in FIG. In FIG. 3, parts having the same functions as the circuits shown in FIGS. 1 and 2 will be described with the same reference numerals. In the case of this shared circuit, a switching circuit 35 and a way selection means 36 are further provided, and the output of the switching circuit 35 selects the PAL matrix circuit 3.
3. The operation of the pulse switch circuit 34 and hue control circuit 19 can be switched. During PAL reception, the control operation of the hue control circuit 19 is stopped, and the burst signal separated by the band amplifier circuit 12 is introduced into the color synchronization circuit 21 as it is. During NTSC reception, the chroma signal derived from the color control circuit 14 passes through a part of the PAL matrix circuit 33 without undergoing matrix processing (B
-Y) demodulator 15 and (RY) mode 17. Further, the subcarrier for (RY) demodulation derived from the hue synchronization circuit 21 is also input to the (RY) demodulator 17 via a part of the pulse switch circuit 34 without undergoing phase inversion processing. As mentioned above, according to the color signal processing circuit that can be used for both PAL and NTSC systems, depending on the received signal system,
The signal processing mode is switched. In the above explanation,
For chroma signals, PAL matrix circuit 3
Switching circuit 3 determines whether or not to perform matrix processing.
5, and for the subcarriers:
A pulse switch circuit 34 determines whether or not the (RY) demodulation axis is to be inverted by 180 degrees every horizontal period. That is, in the above system,
The phase processing function in the color signal processing circuit is switched depending on whether PAL or NTSC is being received. Further, if we focus on the signal differences between the PAL and NTSC system assemblies, we will see, for example, Table 1 below.

[Problems with background technology]

As mentioned above, in multi-system color television receivers, depending on the transmission and color signals to be processed,
It is necessary to perform unique color signal processing for each. Assuming that the color signals to be processed are NTSC color signals and PAL color signals, the burst signal of the NTSC color signal is −
Although it is transmitted with a constant phase of 180 degrees, the burst signal of the PAL color signal is transmitted with a phase of +135 degrees and -135 degrees every horizontal period. For this reason, for example, in a multi-system common color television receiver that processes NTSC color signals and PAL color signals, when performing color killer detection, each color signal to be processed is converted to the above burst signal for color killer detection. Phase-synchronized color subcarriers will be generated. Accordingly, the color killer detection circuits are also provided independently, which necessitates providing a color killer detection circuit for each color signal to be processed, which prevents the color signal processing circuit from being shared. [Object of the Invention] The present invention has been made in view of the problems of the background art described above, and provides a color signal processing device that allows a color killer detection circuit to be shared for a plurality of transmitted color signals to be processed. The purpose is to [Summary of the Invention] In order to achieve the above-mentioned object, the present invention uses, for example, a color subcarrier shown at 88b in FIG. The phase synthesis circuit that generates the signal is
Used as a detection reference signal for color killer detection during PAL signal processing. This allows the color killer detection circuit to be shared when processing different transmission color signals without lowering the detection efficiency. [Embodiments of the Invention] Examples of the present invention will be described below with reference to the drawings. FIG. 5 shows the overall configuration of the color signal processing circuit section in the color television receiver of the present invention. 61 is an input terminal for a chroma signal including a burst signal, and the chroma signal input here is input to a variable gain amplifier 62. The chroma signal subjected to gain control in this variable gain amplifier 62 is
The signal is input to the burst chroma signal separation circuit 63. The burst signal separated by the burst/chroma signal separation circuit 63 is input to a hue control circuit 81, and the chroma signal is input to a color control circuit 64. Further, the burst signal separated by the burst/chroma signal separation circuit 63 is input to an automatic color control (ACC) detection circuit 71, where the amplitude is detected.
A DC voltage obtained by amplitude detecting the burst signal is applied to the gain control terminal of the variable gain amplifier 62. Therefore, the variable gain amplifier 6
Burst chroma signal separation circuit 6 in which the chroma signal output from 2 is always controlled to a stable level.
At 3, the gate pulse from the gate pulse shaping circuit 72 is used to separate the burst signals. This gate pulse is phase-synchronized with the burst signal period, and is output after, for example, a horizontal synchronizing signal is delayed and adjusted to a constant pulse width. The chroma signal separated by the burst chroma signal separation circuit 63 is amplified by the color control circuit 64. The color control circuit 64 is
The gain is varied by adjusting the adjustment volume 65 by the user. The output chroma signal from the color control circuit 64 is sent to the pulse matrix circuit 75 via a 1H delay device 66 having a delay time of one horizontal period and a coupling capacitor 67.
It is applied to the delay input line 75a of the pulse matrix circuit 75, and is also applied to the direct input line 75b of the pulse matrix circuit 75 via an attenuator 68 and a coupling capacitor 69. The specific operation of the pulse matrix circuit 75 will be explained in detail in FIG. In this pulse matrix circuit 75, the system is PAL
When processing television signals of
Matrix processing is performed on a 1H delayed chroma signal delayed by 1H (one horizontal period) of the chroma signal and a direct chroma signal that is not delayed. Through this matrix processing, the (B-Y) component and the (R-Y) component are separated.
7 is input. On the other hand, when the system is processing an NTSC television signal, the operation switch 74 is turned on and the delay input line 7
The 1H daytime chroma signal on 5a is connected to ground. Therefore, only the direct chroma signal is input to the pulse matrix circuit 75. When the operation switch 74 is turned on, the pulse matrix circuit 75 switches its internal signal path, and as a result, the system switch circuit 7
The output state of 9 can also be switched. (The specific configuration of the system switch circuit 79 is also explained in detail in FIG. 6.) When the system is processing an NTSC television signal, the pulse matrix circuit 75 sends the direct chroma signal to two transmission paths. The signals are separated and input to a (B-Y) demodulator 76 and a (R-Y) demodulator 77, respectively. A gate pulse from a waveform shaping circuit 80 that outputs a pulse synchronized with the horizontal synchronizing signal period is also applied to the pulse matrix circuit 75. When this gate pulse is applied, the pulse matrix circuit 75 cuts off the chroma signal. The waveform shaping circuit 80 generates the gate pulse using, for example, a flyback pulse synchronized with a horizontal synchronizing signal. This gate pulse is applied to a flip-flop circuit 8 which will be described later.
6 is also used as a timing pulse to obtain phase inversion operation. The signal output from the pulse matrix circuit 75 is sent to a (B-Y) demodulator 76 and a (R-Y) demodulator 77.
Furthermore, demodulation processing is performed in a (GY) demodulator 78. This (B-Y) demodulator 76, (R-
The specific configuration and operation of the Y) demodulator 77 and the (G-Y) demodulator 78 will be described in detail in FIG. On the other hand, the burst signal whose phase has been adjusted in the hue control circuit 81 is input to a color killer detection circuit 83 (hereinafter referred to as a killer detection circuit) and an automatic phase control detection circuit 84 (hereinafter referred to as an APC detection circuit). Hue control circuit 81
To adjust the adjustment volume 82, the adjustment volume 82 is operated by the user. In the killer detection circuit 83, phase detection is performed between the burst signal and the subcarrier for killer detection, and a voltage corresponding to the phase difference is output as a killer detection voltage. In the APC detection circuit 84, phase detection is performed between the burst signal and the automatic phase control subcarrier, and a voltage corresponding to the phase difference is obtained as an oscillation frequency control voltage. The killer detection circuit 83 and the APC detection circuit 84 are
It performs detection operation in synchronization with the burst signal.
The timing is determined by the gate pulse shaping circuit 7.
determined by the gate pulse from 2. The color voltage from the killer detection circuit 83 is input to the ident and killer circuit 85. This ident and killer circuit 85 is shown in FIGS. 9 and 10.
It is detailed in the figure. The ident and killer circuit 85 controls on/off of chroma signal transmission of the color control circuit 64 and inversion/non-inversion of the flip-flop circuit 86 according to the level of the killer voltage. Furthermore, the ident and killer circuit 85 can also turn on and off the chroma signal transmission path of the pulse matrix circuit 75 by its output. The ident and killer circuit 85 is
Depending on the level of the killer voltage, it is possible to distinguish between a color broadcast reception state and a monochrome broadcast reception state, and furthermore, when receiving a PAL television signal, the inversion and non-inversion operations of the flip-flop circuit 86 are in the correct phase. It is possible to determine whether the phase is correct or the phase is incorrect. The inversion/non-inversion timing of the flip-flop circuit 86 is determined by the gate pulse output from the waveform shaping circuit 80, and can be inverted or non-inverted every horizontal period. Furthermore, the flip-flop circuit 86 is set to an inactive state or an active state by a switching signal from the system switch circuit 79. When an NTSC television signal is being processed, the operation of the flip-flop circuit 86 is stopped, and when a PAL television signal is being processed, the operation of the flip-flop circuit 86 is stopped.
6 starts. The reference oscillation output from the voltage controlled oscillator 87 is introduced into the phase synthesizer 88, and the phase synthesizer 88 outputs, for example, four subcarriers depending on the purpose of use. This phase synthesizer 88
is (B-Y) for adding to the (B-Y) demodulator 76.
Y) subcarrier for demodulation, (RY) subcarrier for demodulation to be added to the demodulator 77, (G-
Y) a correction subcarrier to be added to the demodulator 78;
A killer detection subcarrier to be added to the killer detection circuit 83 is generated. The correction subcarrier is
It is utilized in the (GY) demodulator 78 when an NTSC television signal is being processed. The operation mode of the phase synthesizer 88 is switched by the output of the system switch circuit 79, and the phase state of the (R-Y) demodulation subcarrier is switched between PAL reception and NTSC reception. When receiving a PAL signal, the phase of the (R-Y) demodulating carrier wave is inverted every horizontal period by the output of the flip-flop circuit 86. The specific configuration and operation of the phase synthesizer 88 will be described in detail in FIG.
Two reference oscillation outputs with different vector phases are input, and are used to generate various subcarriers. The voltage controlled oscillator 87 has an oscillation frequency controlled by the detection output from the APC detection circuit 84, and is controlled so as to always obtain an oscillation output phase-synchronized with the burst signal. Next, details of each circuit will be explained. (1) [Description of the pulse matrix circuit 75] FIG. 6 specifically shows an example of the configuration of the pulse matrix circuit 75, the system switch circuit 79, and the operation switch 74. The pulse matrix circuit 75 functions as a matrix circuit that performs vector addition and subtraction between the direct chroma signal and the direct chroma signal when receiving the PAL system, and functions as a separate transmission path for the direct chroma signal when receiving the NTSC system. The operation switch 74 is turned off when receiving PAL format, and turned off when receiving PAL format.
It shall be turned on when receiving a method. A negative horizontal blanking pulse (gate pulse) is applied from the waveform shaping circuit 80 to the base of the transistor Q839. This horizontal blanking pulse causes transistor Q8 to
39 is turned off, but its collector potential increases and the transistor Q8 involved in chroma signal transmission
10, Q813, Q814, and Q817 are turned off and have the function of blocking input signals during the horizontal blanking period (meaning removing burst signals). Further, even if the transistor Q839 is on during the chroma signal period, if the transistor Q840 is turned on by the color killer signal, the pulse matrix circuit 75 immediately cuts off the transmission path of the chroma signal. The matrix circuit 75 functions as a pulse matrix when receiving PAL, and functions as a color amplifier when receiving NTSC. (1)-1 [Operation when receiving the PAL method] When receiving the PAL method, the operation switch 74 is turned off, thereby turning off the transistor Q81.
7, Q818 turns on. As a result, the collector potential of transistor Q818 of the operational amplifier formed by Q817 and Q814 drops at this time. A voltage that is further lower than the collector potential of transistor Q818 by V _F (transistor base-emitter forward potential drop) appears at the emitter of transistor Q842, and this voltage is applied to transistors Q889, Q882, and Q8.
Added to the base of 21. This turns off transistors Q889, Q822, and Q821. (Transistor Q822, Q821
is a transistor that functions to transmit the (R-Y) and (B-Y) chroma signals when receiving the NTSC system, but is turned off when receiving the PAL system. ) (1)-2 [Vector addition in pulse matrix] The direct chroma signal applied to the base of transistor Q810 is
0 collector → resistor R875 → transistor Q
820 and is led to resistor R823. In this case, the direct chroma signal is phase inverted by transistor Q820. Further, the direct chroma signal applied to the base of transistor Q810 is transferred from the emitter of transistor Q810 to resistor R816 to R817.
→ Transistor Q813 → Resistor R876 → Transistor Q823 → Resistor R882 → Resistor R82
It also leads to 6. The direct chroma signal in this path is not phase inverted. The delay chroma signal applied to the base of transistor Q817
Emitter → Resistor R819 → R818 → Transistor Q814 → R877 → Transistor Q8
This transistor Q82
4, and the emitter of transistor Q817 → resistor R819 → R81
8→transistor Q814→resistor R878→transistor Q825→resistor R823. By this, transistor Q
At the connection point between the collector of 824 and resistor R823,
The direct chroma signal and a signal obtained by inverting the delayed chroma signal are added. That is,
Vector subtraction between the direct chroma signal and the delayed chroma signal will be performed. Furthermore, at the connection point between resistor R826 and resistor R883 connected to the collector of transistor Q825,
Vector addition of the direct chroma signal and the delayed chroma signal is performed. The (B-Y) component of the vector addition result is the transistor Q827.
The (RY) component of the vector subtraction result is applied to the base of transistor Q826. (1)-3 [Operation when receiving the NTSC method] When receiving the NTSC method, the pulse matrix circuit 75 performs amplification and distribution processing of the direct chroma signal. The operation switch 74 is turned on at this time. Therefore, the transistor Q818 that constitutes the system switch circuit 79,
The base potential of Q817 becomes low, and transistors Q818, Q883, and Q817 are turned off. Therefore, the transistors Q818, Q883, and Q8 that constitute the system switch circuit 79
Among the transistors 84 and Q819, the collector potential of transistor Q818 becomes high, while the collector potential of transistor Q819 becomes low. As the collector potential of transistor Q818 becomes higher, transistor Q842
The emitter potential of transistors Q889, Q822, and Q82 also increases.
Added to the base of 1. This causes transistors Q889, Q822, and Q821 to transition from the off state to the on state. On the other hand, as the collector potential of transistor 819 becomes lower, the emitter potential of transistor Q841 also becomes lower, and this emitter potential is applied to the bases of transistors Q823, Q824, Q825 and the base of transistor Q820, turning these transistors off. let As a result,
During NTSC reception, transistor Q82 forms the transmission path for the day chroma signal.
5, Q824 is turned off and the day chroma signal is immediately cut off. Therefore, during NTSC reception, the transistor Q82 is connected to the transistor Q82 via the path from the base collector of the transistor Q810 to the resistor R875 to the transistor Q821 to the resistor R880.
6 and is also added to the base of transistor Q8
10 base emitter → resistor R816 → resistor R817 → transistor Q813 → resistor R87
6→transistor Q822→resistor R881 to the base of transistor Q827. The signal applied to the base of the transistor Q827 is transferred from the emitter of the transistor Q827 to the DC cut capacitor C802 to the transistor Q8.
The signal is input to the next stage (B-Y) demodulator 76 via 32 base-emitter paths. Further, the signal applied to the base of transistor Q826 is transmitted from the emitter of transistor Q826 to capacitor C801 for DC cut to transistor Q831.
via the base-emitter path of the next stage (R-
Y) Input to demodulator 77. (1)-4 [Gain in the pulse matrix circuit] The gain of the pulse matrix circuit 75 is automatically switched between when receiving the PAL system and when receiving the NTSC system. In other words, when receiving the PAL system, the vector addition of the direct chroma signal and the delayed chroma signal is performed by the transistor Q8.
The vector subtraction is performed on the collector side of transistor Q824. Vector addition extracts the (B-Y) component, but the resistor R825 acts as a load for the transistor Q823 that amplifies the direct chroma signal, and the resistor (R825+R826) acts as a load for the transistor Q825 that amplifies the delayed chroma signal. ) becomes the load. on the other hand,
Regarding vector subtraction, vector subtraction extracts the (RY) component, and the transistor Q82 inverts the direct chroma signal.
0, the resistor R822 acts as a load, and the transistor Q8 amplifies the delay chroma signal.
For 24, resistor (R822+R823)
becomes a load. Next, during NTSC reception, the load of transistor Q822 is a resistor (R825 + R82
6), and the load of the transistor Q821 is the resistor (R822+R823+R829). As mentioned above, the (B
-Y) component and (RY) component can be switched. By switching this load, the relative amplitude ratio (B-Y)/(R-Y) of the B-Y axis and R-Y axis components is set to 1 when receiving the PAL system and 0.56 when receiving the NTSC system. Can be set. In other words, it is possible to automatically switch and obtain an amplitude ratio appropriate for each method. However, the output DC potential does not change in response to system switching. (1)-5 [Pal matrix operation] In the pulse matrix circuit 75,
It operates to automatically switch the amplitude ratio of (B-Y)/(R-Y) during PAL system processing and NTSC system processing. Now, the current vectors of the direct chroma signal and the delayed chroma signal will be explained as α and β. However, in Figure 6,
The collector current of Q813 is α, the collector current of Q810 is -α, the collector current of Q814 is β
(The formation currents of Q825 and Q824 are both β/2). FIG. 11a shows the vector of the direct chroma signal when receiving the PAL system, and FIG. 11b shows the vector of the daytime chroma signal. (B-
Y) component is 2(B-
Y), and the amplitude is α
It can be expressed as (R825)+β/2(R825+R826). However, R825,R
826 are the resistors R825 and R825 in FIG. 6, respectively.
This is the value of R826. Next, the (RY) component is derived for each horizontal period, and is shown in Fig. 11d.
-2((R-Y) or 2(R-
Y). At this time, the amplitude is β/
2(R822+R823)-α(R822). However, R822,
R823 is the resistor R82 in FIG.
2, the value of R823. When the system is then switched to NTSC processing, only the direct chroma signal shown in FIG. 12a is processed. The chroma signal applied to the (B-Y) demodulator is derived as a composite vector of 2 (R-Y) components and 2 (B-Y) components, as shown in FIG. 12b, and the amplitude in this case is:
It can be expressed as α(R825+R826). However, R825 and R826 are the 6th
These are the values of resistors R825 and R826 in the figure. Also, the chroma signal applied to the (RY) demodulator is
As shown in Figure 12c, it is derived as a composite vector of 3.56 (B-Y) and 3.56 (R-Y) components, and the amplitude in this case is -α (R
823+R829). However, R822, R823, and R829 are the values of the resistors R822, R823, and R829 in FIG. (1)-6 [Modification of the pulse matrix circuit 75] Figures 13a and 13b show other embodiments of the pulse matrix circuit, respectively. To explain from the circuit of FIG. 13a, 91 is:
Reference ground potential line, 92 constant current bias line, 93 base bias line, 75b
75a is a direct chroma signal input line, and 75a is a delayed chroma signal input line. Furthermore, 94 is a switching signal input line from the system switch circuit, and 95 is supplied with a reference voltage. When receiving the NTSC system, the switching signal input line 94 becomes low level. Therefore, transistors Q31, Q35, Q36, and Q34 are turned off. Therefore, the direct chroma signal passes through the path from the base-collector of transistor Q11 to the emitter-collector of transistor Q32,
(RY) component output line 96. Also, the base and emitter of transistor Q11 →
It passes through the resistors R11 and R12 and the emitter-collector path of the transistor Q12→the emitter-collector path of the transistor Q33, and is led to the (BY) component output line 97. Next, when receiving the PAL system, the switching signal input line 94 becomes high level. Therefore, transistors Q35, Q36, Q34, and Q31 are turned on, and transistors Q32 and Q33 are turned off. Therefore, the direct chroma signal is transmitted from transistor Q11 to transistor Q31 to resistor R3.
2, to the (R-Y) component output line 96, and via transistor Q11 → resistor R11 → R12 → transistor Q12 → transistor Q34 → resistor R34
Y) component output line. On the other hand, the direct chroma signal is distributed to the transistor Q36 side and the transistor Q35 side after passing through the transistor Q21 → resistor R21 → R22 → transistor Q22, and is distributed to the (RY) component output line 9, respectively.
6 and (B-Y) component output line 97 side. This makes it possible to obtain matrix processing during PAL processing. The signal applied to transistor Q21 is F _(p
)o and the signal applied to transistor Q11 is F′ _(p)o+1 , then the signal appearing on the output line 97 is F′ _(p)o +F′ _(p)o+1 = {α′(B −Y)±jβ′(R−Y)} +{α′(B−Y)〓jβ′(R−Y)} =2α′(B−Y) Similarly, the signal appearing on the output line 96 is F′ _{( p)o} −F′ _(p)o+1 = ±j2β(R−Y). Next, the pulse matrix circuit shown in FIG. 13b will be explained. In FIG. 13b, using the same reference numerals for the same parts as in FIG.
The 42 constant current sources _I1 are configured to be turned off or on depending on the NTSC system or PAL system processing. During NTSC processing, the constant current source _I1 is turned off, so only the direct chroma signal is delivered to the collector side of the transistor Q43 and the collector side of the transistor Q44. During PAL processing, by turning on the constant current source _I1 , the delay chroma signal is transmitted to the transistor Q4.
After passing through the path 1→Q42, the signal is distributed by transistors Q45 and Q46 to enable matrix processing. (2) [(B-Y), (R-Y), (G-Y) demodulator and phase synthesizer] Figure 7 shows (B-Y), (R-Y), (G-Y) demodulation. FIG. 8 shows a phase synthesizer 88. (2)-1 [(B-Y), (R-Y), (G-Y) demodulator] (When receiving PAL system) The (B-Y) component derived from the emitter of transistor Q832 is
5, supplied to each base of Q861, and derived from the emitter of transistor Q831 (R-
Y) component is provided to the base of transistor Q856. (B-Y) In the demodulator 76,
Transistor Q854, Q855, Q862,
Q863, Q864, Q865 constitute a multiplication circuit, and transistors Q864, Q86
3 from the phase synthesizer 88 (B
-Y) Demodulation subcarrier (B-Y) CW is added. Demodulated signal (B-Y) of (B-Y) component
is derived through a path from the base-emitter of transistor Q874 to resistor R866 via the common collector of transistors Q862 and Q864. Also, demodulated signal of opposite polarity -(B-Y)
is led out from the common collector of transistors Q863 and Q865 to matrix resistor R868. On the other hand, in the (RY) demodulator 78, transistors Q856, Q857, Q86
6, Q867, Q868, Q869 also constitute a multiplication circuit, and transistors Q867, Q8
A subcarrier (RY) CW for (RY) demodulation from a phase synthesizer 88 is added to the common base of 68. The demodulated signal (RY) of the (RY) component is transmitted through transistors Q867 and Q86.
9 -> base/emitter of transistor Q875 -> resistor R870. Also, the demodulated signal of opposite polarity -(R-
Y) is led out from the common collector of transistors Q866 and Q868 to resistor R871. Therefore, the demodulated signal (G-Y) obtained as a result of the matrix of the demodulated signal (B-Y) and -(RY)
is derived through a path from the base-emitter of transistor Q876 to resistor 872. In other words, the demodulated signal (G-Y) is the demodulated signal -(B-
It is obtained by vector synthesis of the demodulated signal -(R-Y) and the demodulated signal -(R-Y). (2)-2 [(B-Y), (R-Y), (G-Y) demodulator] (When receiving NTSC method) (B-Y) demodulator 76, (R-Y) when receiving NTSC method ) The operation of the demodulator 77 is the same as when receiving the PAL system. However, when receiving the NTSC system, the system switch circuit 7
9, the collector potential of transistor Q844 decreases and the collector potential of transistor Q843 increases. transistor Q844
When the collector potential of
0 turns off. As a result, transistor Q86
1, Q858 turns on, matrix circuit 75
The chroma signal from Q861 is led to the collector through the base of transistor Q861. At this time, transistors Q858, Q861, Q87
0, Q871, Q872, Q873 function as a multiplication circuit, and transistors Q873, Q87
1 common collector has a multiplication output of the (G-Y) subcarrier for demodulation (G-Y) CW (actually for vector phase correction of the G-Y axis) and the (B-Y) component, that is, for correction. A demodulated signal (G2-Y) is obtained. Therefore, when receiving the NTSC system, a matrix operation is performed on the three signals demodulated signals (B-Y), -(RY), and (G2-Y), and the resulting signal is the regular demodulated signal ( G−Y). (3) [Description of phase synthesizer 88 and demodulation axis] FIG. 8 shows the phase synthesizer 88. This phase synthesizer 88 and the (B-Y), (RY), (G
-Y) The relationship between the demodulation axes of the demodulators 76, 77, and 78 will be explained with reference to FIGS. 7 and 8. (3)-1 [Demodulation axis during PAL reception] The subcarrier required for color demodulation is generated by a phase synthesizer using a reference oscillation signal created using a burst signal as a reference by an automatic phase control (APC) loop. 88. The (B-Y) demodulation subcarrier (B-Y) CW for the (B-Y) axis is
Transistor Q7 forming phase synthesizer 88
The second reference oscillation signal b is applied to the base of 34. This second reference oscillation signal b is a signal created by delaying the phase of the first reference oscillation signal a, and the first reference oscillation signal a is phase-synchronized with the burst signal.
This is a signal generated in the APC loop including the voltage controlled oscillator 87. When the second reference oscillation signal b is applied to the base of the transistor Q734, a signal b of the same phase appears at the collector of the transistor Q735. This signal b is derived from its collector as a (B-Y) demodulation subcarrier (B-Y) CW via a transistor Q737, and a transistor Q863 shown in FIG.
Added to Q864 common base. Next, the subcarrier (RY) of the (RY) axis (RY) CW
This (R-Y) demodulation subcarrier (R-Y) CW is the first phase synthesizer circuit 88.
It is caused by a. The first phase synthesis circuit 88a includes transistors Q742, Q743,
It is composed of Q744, Q745, Q746, Q747, etc. Transistor Q742
A first reference oscillation signal a is applied to the base of the transistor Q743, and a second reference oscillation signal b is applied to the base of the transistor Q743. Transistor Q742,
Q743 has a differential amplifier circuit configuration, and its emitters are commonly connected and connected to the collector of transistor Q740 that constitutes a constant current source. Therefore, the collector of transistor Q742 has -(a-b)=(ba-a), and transistor Q743
Signals (a-b) appear at the collector of. The signal (b-a) is connected to the collector side of transistor Q745, and the signal (a-b) is connected to the collector side of transistor Q747 through resistor R.
279 can be derived as a load. Here, whether the signal (ba-a) or the signal (a-b) is derived depends on the transistor Q745,
Common base of Q746 and transistor Q74
4. Output from flip-flop circuit 86 added to common base of Q747 (P4, P5)
Determined by state. That is, among the outputs P4 and P5 of the flip-flop circuit 86, the output P
When the level of output P4 is at a high level, -(a-b)=(ba-a) is led out to the resistor R729 through transistor Q745, and when the output P4 is at a low level, (a
-b) is led to resistor R729. As explained in FIG. 5, the state of the flip-flop circuit 46 is inverted every horizontal period.
When receiving the PAL system, the signal (b-a),
(a-b) are output alternately every horizontal period. In other words, R-Y demodulation subcarrier (R-Y)
The phase of CW is reversed every horizontal period, and (R-
Y) component will be demodulated. (R
-Y) Demodulation subcarrier (R-Y) CW is the 7th
It is added to the bases of transistors Q867 and Q868 shown in the figure. During PAL reception, there is a phase difference of 90° between the BY-axis and the RY-axis regarding the subcarrier. During PAL reception, the base potential of transistor Q818 in system switch circuit 79 shown in FIG. 6 is high and the collector potential is low. And transistor Q
The emitter potential of transistor Q842 is also low, so the collector potential of transistor Q844 is high and the collector potential of transistor Q843 is low. The collector potential of the transistor Q843 in the system switch circuit 79 is the same as that of the transistors Q751 and Q755 in the phase synthesizer 88.
It can also be added to the base of Therefore, during PAL reception, the base potential of transistors Q751 and Q755 in the phase synthesizer 88 is low;
is off. Therefore, transistor Q755
is off, its collector is disconnected from resistor R729 and the signal (a-
Only b) and (ba) are derived as subcarriers. Next, the (G-Y) axis during PAL reception will be explained. During PAL reception, transistors Q818, Q819, and Q84 forming the system switch circuit 79 shown in FIG.
1, Q842, Q843, and Q844, transistors Q861 and Q858 of the (GY) demodulator shown in FIG. 7 are turned off. Therefore, the chroma signal (B-Y) component obtained through the emitter of transistor Q832 is cut off by Q861. As a result,
In the G-Y demodulator, the (G-Y) demodulation subcarrier (G-Y) CW and the (B-Y) component are not multiplied. However, in this case,
A predetermined DC voltage appears at the collector of transistor Q873. When receiving the PAL system, as explained in Figure 4b, -(B-
A (G-Y) demodulated signal is obtained by a matrix of a demodulated signal of Y) and a demodulated signal of -(R-Y). (3)-2 [Demodulation axis when receiving the NTSC method] When receiving the NTSC method, the pulse matrix circuit 75 used when receiving the PAL method is shared, and serves as a transmission path for chroma signals as well as a separation path. functions as During NTSC reception, the operation of the flip-flop circuit 86 is stopped by the system switch circuit 79. When receiving the NTSC method, the demodulation phase of the demodulation axis is different from that when receiving the PAL method, and the relative phase difference between the (B-Y) axis and the (R-Y) axis is set to approximately 105 degrees. . The relative amplitude ratio of demodulated signals also differs between the NTSC system and the PAL system. This is because the white color temperature settings are different between the PAL system and the NTSC system. This system is switched to satisfy such conditions. During NTSC reception, the state of each transistor constituting the system switch circuit 79 is reversed from the state during PAL reception. Therefore, in the phase synthesizer 88, transistors Q741, Q751, and Q755 are turned on.
Transistor Q760 turns off. When transistor Q741 turns on, transistor Q74
2, Q743 is turned off. Next, when transistor Q751 turns on, transistor Q75
2, Q753 is turned off. Subcarrier for B-Y demodulation (B-Y) CW during NTSC reception
is extracted in the same way as when receiving the PAL system. On the other hand, transistors Q749, Q750, Q
751, Q752, Q753, Q755, etc. form a second phase synthesis circuit 88b. A resistor R733 is connected to the base of transistor Q750.
is connected, the reference oscillation signal a is
Its absolute value is varied to K ₁ ·a (0<K ₁ <1) and is applied to the base of transistor Q750. Furthermore, since the resistor P731 is also connected to the base of the transistor Q749, the reference oscillation signal b is applied to the base of the transistor Q749 with its absolute value varied to K ₂ ·b.
As a result, a vector signal K ₂ ·b−K ₁ ·a appears at the emitter of transistor Q755. When receiving the NTSC system, the operation of the flip-flop circuit 86 is stopped and the outputs P4, P
5 is at a low level, transistors Q756, Q752, Q746, Q745, Q
754, Q753, Q747, and Q744 are off. Therefore, on the collector side of the transistor Q755, a signal (K ₂ · b - K ₁ · a) having a phase set at approximately 105° with respect to the (B-Y) axis is used for (R-Y) demodulation. Subcarrier (RY) is derived as CW. Since phase adjustment is based on vector synthesis, it is performed by selecting the values of resistors R732 and R731. It was extracted like this (R
-Y) Demodulation subcarrier (R-Y) CW is the 7th
It is added to the common base of transistors Q867 and Q868 shown in the figure. In this way, (R-
The subcarrier (R-Y) CW of the Y) axis is (B-
(Y) axis with a phase difference of 105°. Furthermore, in the (RY) demodulator 77, the (RY) component is transmitted to the pulse matrix circuit 7.
In step 5, the amplitude of the (B-Y) component is adjusted and input, so that demodulation compatible with the NTSC system is performed. Next, the (G-Y) axis during NTSC reception will be explained. Even when receiving NTSC format,
The (G-Y) axis needs to have the same phase as when receiving the PAL system. However, when the system switches from the PAL processing state to the NTSC processing state, the gain for the (RY) component in the pulse matrix circuit 75 is higher during NTSC processing than during PAL processing. becomes larger. Therefore, as with PAL processing (G-
Y) If the demodulator 78 simply performs matrixing, the vector distribution of the demodulated signals (B-Y) and (R-Y) will be different from that of PAL system processing.
Y) axis cannot be obtained at the desired phase. Accordingly
When receiving the NTSC system, it is necessary to correct the (G-Y) axis phase of the (G-Y) signal. The (G-Y) axis correction means during NTSC reception will be explained. The (G-Y) demodulated signal is demodulated by performing matrix processing of the (B-Y) demodulated signal and the (R-Y) demodulated signal when receiving the PAL system, but when receiving the (B-Y) demodulated signal when receiving the NTSC system, In addition to the -Y) demodulated signal and the (RY) demodulated signal, demodulation processing is performed using the (B-Y) component as the detected output of the (G-Y) demodulation subcarrier (G-Y) CW. That is, in the phase synthesizer 88, transistors Q764, Q765, Q7
67, Q768, Q769, etc. constitute a third phase synthesis circuit 88c. transistor Q
Since the resistor R737 is connected to the base of 764, the reference oscillation signal a is l ₁ · a (0<
l ₁ <1), the transistor Q764
is applied to the base of Also, transistor Q
Since the resistor R739 is connected to the base of 765, the reference oscillation signal b is l ₂ · b (0<
l ₂ <1), the transistor Q765
is applied to the base of Therefore, a vector signal of (l ₂ · b - l ₁ · a) is obtained at the collector of the transistor Q764, and this signal is transmitted to the (G-Y) demodulation subcarrier ( G-Y) CW is added to the common base of transistors Q872 and Q871 of the (G-Y) demodulator 78. By this, (G-
Y) In the demodulator 78, the transistor Q8
The chroma signal added to the base of 61 and the (G
-Y) Demodulation subcarrier (G-Y) is multiplied by CW, and the resulting vector signal becomes one of the matrix elements as a correction vector signal. With this kind of operation, NTSC
When receiving the system, it is necessary to have the correct demodulation axis (G-
Y) A demodulated signal is obtained. That is, since the correct (G-Y) axis cannot be obtained in a matrix circuit adapted for PAL processing, a subcarrier (G-Y) CW for correction is generated in the phase synthesis circuit 88c. As shown in Fig. 14, the correction vector (G-
Y) It creates UD. By this,
Correct (G-Y) axis demodulation output can be obtained. (3)-3 [Stabilization of phase synthesis in the second phase synthesis circuit 88b and third phase synthesis circuit 88c] In the phase synthesis circuit, the reference oscillation signal a.
Although phase synthesis of phase b is performed, it is necessary to ensure that the synthesized output is not affected by the current amplification factor h _fe of the transistor. Now, a description will be given of countermeasures taken for the phase synthesis circuit composed of transistors Q749 and Q750. Now, in this phase synthesis circuit, resistor R73
If 3 were not present, the following problem would arise. FIG. 15a shows a simplified phase synthesis circuit in which the resistor R731 is removed, but with this configuration, the phase synthesis output is unstable. In FIG. 15a, reference signal a is input to the base of transistor Q750 via a path from the base emitter of transistor Q1 to resistor R732, and reference signal b is input to the base of transistor Q749 via the base emitter of transistor Q2. Assume that the value of resistor R732 is 1KΩ, and the value of resistor R733 is 5KΩ. FIG. 15b shows the reference signal a
FIG. 15c is an equivalent circuit when viewed from the reference signal b. However, in the figure, h _ie1 and h _ie2 are the base input impedances of Q749 and Q750, respectively, and r _e is the emitter resistance. Using this circuit, transistor Q
Let's find the base input voltage of 749 and Q750. h _ie1 = h _ie2 = KT/q×2(h _fe +1)/i ₀ K...Boltzmann multiplier (1.38×10 ^-23J/K ) q...Electron charge (1.6×10 ^-19 coulombs) T... ...Absolute temperature KT/q...26mV (approximate at room temperature) i ₀ ...Transistor emitter current r _e =KT/q×1/i ₀ = 0.045K Base input υ _io (a) of transistor Q750 is The base input υ _io (b) of the transistor Q749 becomes υ _io (b)=b. When h _fe is changed to 50, 100, and 300, the input vectors are 0.733a; 0.792a;
0.818a;b, and the output color subcarrier composite vector c is amplified by resistance-divided K ₁ ·a and b, and its phase error ΔQ changes by about 7°. That is _{, the} current amplification _factor h _fe
will be influenced by. When the subcarrier fluctuates in this way, accurate color demodulation cannot be obtained. Furthermore, when the phase synthesis output is used in a killer detection circuit, a malfunction may occur in the color killer operation. In order to prevent the above-mentioned phase fluctuation, the system of the present invention further includes a resistor R731, as shown in _FIG . to obtain stable phase synthesis output. That is, the simplified circuit configuration in this case is shown in FIG. 16a, and the equivalent circuit is as follows.
The result is as shown in FIGS. 26b and 26c. From this circuit, the base input voltages of transistors Q749 and Q750 are determined as follows. Resistor R732 = 1KΩ, Resistor R733 = 5K
Ω, resistance R731=800Ω. Base input of transistor Q750 υ _io (a)
teeth, The base input υ _io (b) of transistor Q749 is becomes. When h _fe changes to 50, 100, and 300, the input vectors are (0.744a, 0.896b), respectively.
(0.794a, 0.935b) (0.818a, 0.981b), and the output phase composite vector c is differentially amplified by K ₁・a and K ₂・b, which are resistance-divided at the input, and the phase error is approximately Within 1°. That is, as shown in FIG. 16(d), the low phase composite vector c has a stable phase almost unaffected by the current amplification factor _hfe . Therefore, it can be used for accurate color demodulation and phase detection operations. (4) [Color Killer Detection and Color Killer Operation] Since the Color Killer detector is shared for PAL signal and NTSC signal processing, the Color Killer detection axis is the NTSC signal when processing either system signal. (R-Y) during color demodulation
The phases of demodulation subcarriers are made substantially equal. The color killer detection circuit 83 required to control the color killer operation detects PAL signals and
Commonly used for NTSC signals, and the phase of the color killer detection axis for PAL signals is obtained by phase synthesis circuits 88 and 88b during NTSC signal processing (R-Y)
The phase shall be substantially equal to that of the demodulation subcarrier. That is, the color killer detection axis signal for the PAL signal is obtained using the phase composite signal 88b that generates the (RY) demodulation subcarrier of the NTSC signal. Therefore, when performing color killer processing on a PAL signal, there is no need for a separate circuit for generating a phase signal of the color killer detection axis. The ident and killer circuit 85 also includes a killer filter 90 that holds the detected output voltage of the color killer detection circuit 83 at predetermined intervals.
It functions as a switching circuit that performs switching operations in response to the voltage. With the switching function of this ident and killer circuit 85,
Color killer operation is performed on both NTSC and PAL signals, and it is checked whether the burst swing timing of the transmission burst signal and the phase inversion timing of the (R-Y) demodulation subcarrier match during PAL signal processing. An ident movement is performed. That is, the switching function of the ident and killer circuit 85 performs the ident operation. The above IDENT operation controls the output phase of the flip-flop circuit 86 during PAL signal processing to match the phase of the (RY) demodulation subcarrier with the burst swing phase, but the flip-flop circuit 86 is used for NTSC signal processing. The above ident circuit and killer circuit 85
The oscillation operation is stopped by the control of For this reason,
The phase inversion control operation of the (R-Y) demodulation subcarrier used as the color killer detection axis in PAL signal processing is stopped during NTSC signal processing, and the (R-Y) demodulation operation of the NTSC signal is performed when receiving the NTSC signal. . FIG. 9 shows the killer detection circuit 83 and the ident and killer circuit 85. Killer detection circuit 83
is the burst and killer detection subcarrier separated by the burst chroma separation circuit 63.
CW), and as a result, a killer detection output voltage V _O is derived to the killer filter 90. The ident and killer circuit 85 is composed of two killer comparators, each having a predetermined reference voltage V _H and V _{L .}
The killer detection output voltage is compared with the killer detection output voltage, and the operation of various circuits is specified as a result. Here, the reference voltage V _L indicates the base voltage of the transistor Q664 of the ident and killer circuit 85, and V _H indicates the base voltage of the transistor Q662. In the embodiment of the present invention, when V _O > V _H , the color reception mode is set, when V _O < V _H , the killer operation mode is set, and when V _O < V _L
The mode becomes Ident operating mode. Note that the Ident operation mode is valid only in the PAL reception mode, and the Ident operation is not performed in the NTSC reception mode. The circuit operation will be explained below for each case. . (4)-1 [Color killer operation when receiving NTSC signal] When the system switch 74 shown in FIG. 6 is connected to the NTSC side, the system enters the NTSC reception mode. At this time, the transistor Q of the system switch circuit 79
843 collector voltage is high, transistor Q
The collector voltage of 844 is low. Therefore, in FIG. 8, transistor Q755 in phase synthesizer 88 is turned on, and transistor Q75
6. Q754 is off, and at the same time, transistor Q760 is off and transistor Q75 is turned off.
8, Q759 is turned on. As a result, transistors Q758 and Q759 are connected to the voltage controlled oscillator 8.
The transistor Q762 operates as a differential amplifier that receives the output signal b of the transistor Q762, and generates a vector component of the signal b at the collector of the transistor Q762. This is the transistor Q633 and Q6 of the killer detection circuit 83 as the subcarrier for color killer detection (Killer-CW).
34 common bases. Assuming that NTSC color broadcasting is being received now, a burst signal is added to the base of transistor Q630, and as a result of multiplication with the above-mentioned subcarrier for color killer detection (Killer-CW), killer filter 90 is activated. The voltage (killer detection voltage) V _O increases. This killer detection voltage V _O
is applied to the base of transistor Q663 of ident and killer circuit 85. Also,
The aforementioned reference voltage V _H is applied to the base of the transistor Q662. Therefore, the killer detection voltage V _O rises and when V _O >V _H , transistor Q659 is turned on and Q658 is turned off.
The current in Q665 decreases. in this way,
During NTSC processing, when a burst signal is detected at normal field strength, transistor Q
665 is turned off, and the transistor Q84 which controls the pulse matrix circuit 75 explained in FIG.
Turn off 0. When transistor Q840 is off, pulse matrix circuit 75 functions as a transmission path and distribution path for gain-controlled NTSC chroma signals, and a predetermined color demodulation operation is performed in the color demodulation circuit. On the other hand, when a black and white broadcast is received or in a weak electric field, the transistor Q6 of the killer detection circuit 83
No burst signal appears at the base of 30.
Therefore, the voltage V _O of the killer filter 90 has a constant value determined by the base voltage of the transistor Q652 regardless of the output voltage of the killer detection circuit 83. This voltage is lower than the base voltage (V _H ) of transistor Q662, and transistor Q665 of ident and killer circuit 85 is turned on. As a result, transistor Q840, which controls pulse matrix circuit 75, is turned on. When this transistor Q840 is turned on, the transistors Q810, Q813, Q814 in FIG.
All Q817s are turned off, the chroma signal transmission path is cut off, and a color killer operation is performed. In this way, all the chroma signal transmission paths of the pulse matrix circuit 75, which functions as an amplifier, can be cut off for NTSC color signals by the collector output of the transistor Q665, but the collector output of the transistor Q665 , is also supplied to a switch circuit (not shown) that turns on and off the output of the band pass filter in the color control circuit 64, and the output of the band pass filter itself is also cut off, making it possible to perform a double color killer operation. FIG. 10 shows a flip-flop circuit 86. During NTSC reception, the collector potential of the transistor Q843 of the system switch circuit 79 is high, and therefore the 10th
Transistors Q845, Q846, Q84 in the diagram
7, Q667 is on. Therefore, the switch composed of transistors Q668 and Q669 is turned off during NTSC reception, and transistor Q670 is turned off. transistor Q
670 turns off, the flip-flop circuit 8
No energizing voltage is applied to 6, and the operation stops. Therefore, outputs P4 and P5 of the flip-flop circuit 86 both become low level during NTSC processing, and the phase inversion control operation in the phase synthesis circuit 88b that synthesizes the (R-Y) demodulation subcarrier is stopped, and the (R -Y) Color demodulation is appropriately performed in a color demodulation circuit. (4)-2 [Color killer operation and ident operation when receiving PAL system signals] In the PAL system, the burst signal is -(B
-Y axis), the phase swings by ±45° every horizontal period, and it is necessary to synchronize the color killer detection subcarrier (Killer-CW) with this phase state. For this reason, a flip-flop circuit 86 and an identification circuit which are unnecessary for receiving NTSC signals are provided. When the system switch 74 in FIG. 6 is set to the PAL side, the system enters the PAL reception mode. At this time, the collector potential of the transistor Q843 of the system switch circuit 79 becomes low, and the 10th
Transistor Q of flip-flop circuit 86 in the figure
845, Q846, Q847, and Q667 are turned off, and the transistor Q66 forming the switch is turned off.
8, Q669 turns on. Therefore, transistor Q670 turns on,
An energizing voltage is applied to this flip-flop circuit 86 and it becomes operational. Furthermore, a gate pulse synchronized with the horizontal synchronizing signal is applied to the base of the transistor Q667 of the flip-flop circuit 86, thereby inverting the states of the outputs P4 and P5 every horizontal period. Next, in the phase synthesis circuit 88 shown in FIG. 8, when receiving a PAL signal, the system switch circuit 79 switches transistors Q751 and Q7.
55 turns off. Therefore, transistor Q7
52, Q753, Q754, Q756 can be in the on state, but transistors Q753, Q7
54 and transistors Q752 and Q756
Which one of the pair is turned on is determined by the states of the outputs P4 and P5 of the flip-flop circuit 86. That is, the output P4 of the flip-flop circuit 86 is output from the transistors Q752 and Q752.
The output P5 is applied to the bases of transistors Q753 and Q754. Now, output P4 is high level, output P
5 is low level, transistor Q75
A signal of (K ₂ · b - K ₁ · a) is derived as a killer detection subcarrier (Killer-CW) through the collector of transistor Q756 → the collector of transistor Q756, and the output P4 is low level and the output P5 is high level. Then, a signal of (K ₁ ·a−K ₂ ·b) is derived as a killer detection subcarrier (Killer-CW) via the collector of the transistor Q749 and the collector of the transistor Q753.
In other words, the output P of the flip-flop circuit 86
4. Depending on the state of P5, the subcarrier for killer detection (Killer-CW) is (K ₁・a−K ₂・b), −
It is controlled to have one of the phases of (K ₁ ·a−K ₂ ·b) and is applied to the killer detection circuit 83 . Also,
During PAL reception, the collector potential of transistor Q844 in system switch circuit 79 is high, so transistor Q760 in phase synthesizer 88 is on, and transistors Q758 and Q759 are off. Therefore, transistor Q762 is also off, and resistor R734 is connected to transistors Q756 and Q75.
3 alternately acts as a load every horizontal period. The color killer detection subcarrier (Killer-CW) obtained as described above is transmitted through transistors Q633 and Q6 of the killer detection circuit 83 shown in FIG.
Added to 34 common bases. In the killer detection circuit 83 shown in FIG. 9, as described above, the flip-flop circuit 8
A multiplication operation is performed between the killer detection subcarrier (Killer-CW) whose phase is inverted by the output of 6 and the burst signal whose phase swings every horizontal period. Therefore, the output obtained from the killer detection circuit 83 during PAL signal processing includes information on whether the color killer operation is performed or not, as well as information on whether the output phase of the flip-flop circuit 86 matches the burst swing phase. It also includes identity information indicating whether or not the ID is rejected. (5) [Control operation for flip-flop circuit by ident operation] Now, in the color killer detection circuit 83, the killer detection subcarrier (Killer-CW) is added to the bases of transistors Q633 and Q634.
If the phase of and the swing of the burst signal (±45° swing) are in the correct relationship, that is, the subcarrier (Killer-CW) and the (RY) component are in phase, the current flowing through transistors Q639 and Q641 increases. When the current of transistor Q641 increases, the output voltage V _O of killer filter 90 increases, and the terminal voltage of the killer filter also increases. As a result, the emitter current of transistor Q663 of the ident and killer circuit 85 increases, and transistors Q660 and Q
659 turns on. Transistor Q660,Q
When 659 is turned on, transistors Q661,
Q658 turns off, and along with this, transistors Q666 and Q665 turn off. Therefore, no current is supplied from the collector of transistor Q666 to the emitter of transistor Q675 constituting flip-flop circuit 86. This means that the oscillation operation of the flip-flop circuit 86 is not controlled in any way, and the flip-flop circuit 86 continues the oscillation operation of the current phase. In other words, the subcarrier (Killer−
CW) and the (RY) component of the burst signal are in phase, the state of flip-flop circuit 86 is not controlled. During PAL reception, the demodulation subcarrier (R-Y) obtained from the second phase synthesis circuit 88b in FIG.
The phase of CW is inverted by the outputs P5 and P4 of the flip-flop circuit 86 every horizontal period. Furthermore, when flip-flop circuit 86 is operating in the correct phase as described above, transistor Q665 is turned off.
This causes transistor Q840 to remain off. Therefore, the pulse matrix circuit 75
It also works normally without any killer action. Also, at this time, the pulse matrix circuit 7
5 performs addition and subtraction processing on chroma signals to derive the (RY) and (BY) components, as described above. Next, when receiving the PAL method, if the phase inversion state of the killer detection subcarrier (Killer-CW) and the phase inversion state of the (R-Y) component of the burst signal are opposite and different. I will explain about it. During NTSC signal processing, the (R-Y) demodulation carrier phase is used as the killer detection subcarrier (Killer-CW) during PAL signal processing, so the swing phase of the burst signal and the killer detection subcarrier phase do not match. In the killer detection circuit 83 of FIG. 9,
The detection voltage becomes low. In other words, the output voltage V _O of the killer filter 90 becomes lower. Therefore, the emitter potential of transistor Q663 of the ident and killer circuit 85 becomes low, transistors Q660 and Q659 are turned off, transistors Q661 and Q658 are turned on, transistors Q666 and Q665 are turned on, and transistor Q6
66 turns on, its collector current flows through transistor Q675 of flip-flop circuit 86.
is supplied to the emitter of transistor Q674, which causes flip-flop circuit 86 to stop oscillating. In this state, the killer filter output voltage V _O
The voltage continues as long as the base voltage of the E660, which has dropped from V _F , is lower than the voltage predetermined by the internal bias (here, V _L ), which is further lower than the voltage at which V _F has dropped (V _L - V _F ). be done. On the other hand, the phase of the killer detection subcarrier (Killer-CW) supplied to the killer detection circuit 83 is
It is set near the (RY) axis during NTSC signal demodulation so that the (RY) axis component of the burst signal is large when it is positive and small when it is negative, and from the killer detection circuit 83 to the flip-flop circuit 86. The phase of the killer detection subcarrier (Killer-CW) when the flip-flop circuit 86 enters the stop mode is set so that the (RY) axis component is in the positive direction. ing. Therefore, from the moment the flip-flop circuit 86 stops, the killer detection output in the killer detection circuit 83 generates a large positive output and a small negative output, and as a result, the killer filter output voltage V _O increases. . At the moment when this filter output voltage V _O becomes V _O V _L with respect to the above V _L , transistors Q660 and Q66 of the ident and killer circuit 85
The on/off states of the flip-flop circuit 86 are reversed, thereby turning off the transistor Q666 and turning off the transistor Q674 of the flip-flop circuit 86.
The base voltage of the flip-flop circuit 86 is now controlled by the transistor Q677, and the flip-flop circuit 86 starts oscillating from the next horizontal synchronizing pulse. At this time, if the (R-Y) component of the input burst signal and the subcarrier for killer detection (Killer-CW) are in the correct phase relationship, the killer detection voltage will further increase, and the transistor Q6
The killer comparator at Q658 is inverted, so transistor Q665 is turned off, the color killer condition is released, the color reception mode is entered, and the correct color appears on the screen. Next, if we go back to the point in time when the voltage became V _O V _L and the flip-flop circuit 86 started inverting/non-inverting operation as described above, we can see that the (RY) component of the input burst signal and the killer detection The subcarriers used (Killer-CW) do not always have the correct phase relationship, and there is a probability that they will have a phase difference of 180°. At this time, the killer filter output voltage starts to drop again from V _O V _L , and after several horizontal periods, transistors Q661 and Q660 as identity comparators are inverted again, which turns on transistor Q666 and turns on the flip-flop. The base of transistor Q674 of circuit 86 is forced high, causing flip-flop circuit 86 to stop operating.
As a result, the terminal V _O of the killer filter starts rising toward V _L again, as described above.
When V _O reaches V _L , whether V _O rises further or falls again is determined by the phase relationship between the (RY) component of the burst signal and the subcarrier (Killer - CW). . In reality, when the flip-flop circuit 86 is released from the stopped state, whether the phase relationship between the (RY) component of the burst signal and the subcarrier (Killer-CW) is correct or incorrect is determined by the following: The probability is assumed to be 50%, and the probability that the flip-flop circuit 86 continues to be in a stopped state in an error state is small. Therefore, correct color reception conditions can be obtained within a finite time. As mentioned above, if the phase relationship between the (R-Y) component of the burst signal and the subcarrier (Killer-CW) is wrong, the ident and killer circuit 8
5, the flip-flop circuit 86 is temporarily stopped by the function of the ident comparator by the transistors Q661 and Q660.
It's about starting again. Furthermore,
In the ident and killer circuit 85, a killer comparator is also configured by transistors Q659 and Q658, and the transistor Q
A killer voltage can also be output through the 655 collector. When receiving the PAL method, the subcarrier (Killer
-CW) and the (R-Y) component of the burst signal are out of phase, the killer detection voltage becomes a low voltage (voltage lower than the set voltage V _L ), and the operation of the flip-flop circuit 86 stops (killer detection voltage (begins to operate as the temperature rises), and
Color killer action can be obtained. Additionally, when a burst signal is not detected during PAL reception, a color killer operation is obtained first, and the killer filter output voltage V _O at that time is V _L
V _O V _H. Therefore, in this case, the operation of flip-flop circuit 85 continues. next,
When the (R-Y) component of the burst signal and the subcarrier (Killer-CW) have the correct phase relationship,
A high voltage V _H or higher is obtained as the killer detection voltage, and both transistors Q655 and Q666 are off. That is, as shown in FIG. 17, if the output voltage of the killer filter 90 that samples and holds the detection output is equal to or higher than _VH , the color killer operation is stopped and the swing phase of the (RY) demodulation subcarrier is correct. It is determined that the killer filter 9
If the output voltage of 0 is V _H V _O V _L , color killer operation is performed, but the above (R-Y)
The swing phase of the demodulation subcarrier is determined to be correct. Next, when V _O >V _L , a color killer operation is performed, and it is determined that the swing phase of the (RY) demodulation subcarrier is incorrect, and the flip-flop circuit is controlled. [Effects of the Invention] As described above, according to the color demodulation device according to the present invention, a color killer detection circuit can be shared in a multi-system common color television receiver. Even in this sharing, the detection efficiency in the color killer operation is not affected, so the color killer operation can be performed for each transmitted color signal without causing any malfunction of the color killer.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing a color signal processing circuit for NTSC system, Figure 2 is a block diagram showing a color signal processing circuit for PAL system, and Figure 3 is a color signal processing circuit for both PAL and NTSC systems. The configuration diagram shown in FIG. 4a is
FIG. 4 is a circuit diagram showing a color demodulation circuit of the circuit shown in FIG. 3, FIG. 4 b and c are vector diagrams shown to explain the operation of the circuit shown in FIG. 4 a, and FIG. FIG. 6 is a circuit diagram specifically showing the pulse matrix circuit and system switch circuit in FIG. 5, FIG. 7 is a circuit diagram specifically showing the demodulator in FIG. 5, and FIG. is a circuit diagram specifically showing the phase synthesizer shown in Fig. 5, and Fig. 9 is a circuit diagram showing the killer detection circuit shown in Fig. 5.
FIG. 10 is a circuit diagram specifically showing the flip-flop circuit and the IDENT and killer circuit in FIG. 5. FIGS. 11 and 12 are circuit diagrams specifically showing the operation of the pulse matrix circuit. Vector diagram shown for explanation, No. 13
Figures a and b are circuit diagrams showing other combined embodiments of the pulse matrix circuit, and Figure 14 is for explaining the (G-Y) axis demodulation operation of the demodulator and phase synthesizer in Figure 5. Figure 15a is a basic circuit diagram of the phase synthesizer, Figures 15b and c are diagrams showing the equivalent circuit of the circuit in Figure 15a, and Figure 15d is the phase diagram of the circuit in Figure 15a. The explanatory diagram shown to explain the synthesis operation, FIG. 16a, is a basic circuit diagram of the phase synthesizer used in the device of FIG. 5, and FIG. 16b,
Figure 16c is an equivalent circuit diagram of the circuit in Figure 1A, Figure 16D is an explanatory diagram shown to explain the phase synthesis operation of the circuit in Figure 1A, and Figure 17 is the same as that shown in Figures 5 and 9. FIG. 3 is an operation explanatory diagram shown to explain the operation of the ident and killer circuit. 66...1H delay device, 75...Palmatrix circuit, 76-78...Demodulator, 79...System switch circuit, 83...Killer detection circuit, 8
5...Ident and killer circuit, 86...Flip-flop circuit, 87...Voltage controlled oscillator, 8
8... Phase synthesizer.

Claims (1)

[Claims] 1. A color carrier in which a color signal is transmitted by first and second modulation axes that are orthogonal to each other, and in which a subcarrier and a burst signal for the second modulation axis are inverted every horizontal period. processing a first composite color signal comprising a signal;
and a second composite color signal in which the color signal is transmitted by first and second modulation axes orthogonal to each other, and the subcarrier and burst signal for the second modulation axis are not inverted every horizontal period. In the color signal processing circuit that performs the processing, a system switch means for generating a system switching signal for switching which signal, the first composite color signal or the second composite color signal, is to be processed; (R-Y) subcarrier generation means for performing (R-Y) axis color demodulation on the color signal; and color killer processing on the first composite color signal in accordance with switching control by the system switch means. In this case, a burst signal of the first composite color signal is input, and the (RY) subcarrier for the second composite color signal generated by the (RY) subcarrier generating means is detected as a detection signal. and a color killer detector for detecting the presence or absence of a burst signal of the first composite color signal using a phase signal substantially equal to the (RY) subcarrier for the second composite color signal. A color signal processing device characterized in that it is used as a detection signal of the color killer detector.