JPS62269591A - Color television receiver - Google Patents

Abstract

PURPOSE:To simplify a processing circuit and to decrease a cost by taking out the first and second CW signals from a variable control oscillating circuit for a PAL color signal processing circuit and inputting a line successive signal after phase modulation to the above-mentioned circuit when the line successive signal of an SECAM color signal is phase-modulated by the first and second CW signals having a 90 deg. phase difference mutually. CONSTITUTION:The first CW signal C1 guided to an SECAM/PAL converting part SC and the second CW signal C2 to phase-advance this to 90 deg. are given to a phase modulating circuit 6 for PAL. Thus, at the output line L2 of the modulating circuit 6, the phase-modulated R-Y and B-Y line successive signal can be obtained. An output signal A after modulation is inputted to a band pass filter 15 in a PAL processing part PP, and the burst signal is removed by a gate circuit 16 and derived as a signal E. The signal E is inputted to a 1H delay circuit 17 and adder subtractor circuits 18 and 19. A B-Y signal and an R-Y signal demodulated respectively by demodulating circuits 20 and 21 are obtained and a G-Y signal is generated by a matrix circuit 22.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial field of application The present invention is applicable to television receivers, especially SECAM signals and
The present invention relates to a dual type color television receiver capable of receiving AL signals.

(b) Conventional technology In recent television receivers, the color signal processing circuit for SECAM is not provided separately from that for PAL in order to be able to change to a dual receiver by retrofitting. Convert the name to a PAL color signal,
This is a PAL color signal processing circuit that performs color demodulation and reproduction. SEC used in this case
As an IC for AM/PAL conversion, Philips T
There is a DA3592A, and its details can be found in the company's Laborator, which was published in 1 sun on January 29, 1986.
yReport” Nct ETV8602.

FIG. 3 shows a schematic configuration of a SECAM/PAL conversion circuit using the above IC. In the same figure, the SECAM color signal frequency-corrected by the bell filter (1) is directly input to the FM demodulation circuit (3) in the IC (2), where it is demodulated and R-Y, B- Y! *Sequential signals can be obtained. Then, the DC levels of this signal during the R-Y and B-Y periods are aligned by the clamp circuit (4), and the burst pulses from the burst pulse generation circuit (5) are inserted into each horizontal blanking period. The PAL modulation circuit (
6). This modulation circuit (6) has a phase difference of 90° from the CW (carrier wave) oscillation circuit (7).
Obtain the first and second CW signals of 43MH2 and perform phase modulation of the fi sequential signal into which burst pulses have been inserted. At this time, in the B-Y period of this line sequential signal, the color difference No. 3 portion uses the first CW signal. and the burst pulse portion is the first
Each signal is modulated using a signal obtained by inverting the CW (I! signal) by 180°, and both the color difference No. 18 portion and the burst pulse portion of the RY period are modulated using the 20 W signal.
The output signal is (A) in Figure 4, and this output signal (A) is obtained by passing it through a variable resistor (VH2) for level adjustment (B) and an IH delay line (11). The resulting signal (C) is vector-combined in a matrix circuit <9). At this time, the phases of the R-Y signals are alternately inverted and synthesized by the output of the flip-flop (8), so a color signal (D) that has been converted into a PAL signal format is obtained from this matrix circuit (9). That is why it is done.

Note that the circuit (7) in the IC (2) is the FM demodulation circuit (3).
Detecting the level difference between the R-Y period and the B-Y period of the line sequential signal output from the clamp flop 8)
This is an ID circuit that controls the inversion operation to be normal.

(C) The problem that the invention aims to solve By the way, the third problem
In the circuit shown in the figure, a crystal oscillator (X+) for the CW oscillation circuit (10) is used to convert the SECAM signal to a PAL signal.
, IH delay line (11), etc. are required separately from those provided in the PAL color signal processing circuit. For this reason, when realizing a SECAM/PAL dual type receiver, there is a drawback that the cost increases accordingly.

Therefore, the present invention has been made with the above-mentioned points in mind, and the above-mentioned C
SECA without providing W oscillation circuit or IH delay circuit
The purpose of the present invention is to inexpensively realize a color television receiver that can perform color demodulation and reproduction of an M signal using a PAL processing circuit.

(d) Means for Solving the Problems In the color television receiver of the present invention, R-Y, B-YIiJl obtained by directly demodulating SECAM color signals
When phase modulating the B-Y and R-Y signals in the ji-order signal with the first and second CW signals having a phase difference of 90 degrees, the first and second CW signals are used for the PAL color signal processing circuit. In addition to switching the variable control oscillation circuit to fixed frequency oscillation operation and extracting it from the oscillation circuit, an IH delay circuit and an addition/subtraction circuit for separating R-Y and B-Y of the PAL color code,
The line-sequential signal after phase modulation is input to a PAL color signal processing circuit including an R-Y, B-Y demodulation circuit, and the like.

(e) Effect: With the above configuration, the line sequential signal adjusted by the phase liquid is P
After being converted into a R-Y%B-Y simultaneous signal by the delay circuit and addition/subtraction circuit in the AL color signal processing circuit, it is color demodulated by the R-Y and B-Y demodulation circuits in the color signal processing circuit. Can be played.

(v) Embodiment FIG. 1 shows an embodiment of the present invention, and this embodiment will be explained below with reference to FIG. 2, where the same parts as in the above-mentioned FIG. The explanation is incorporated by reference.

The circuit in Fig. 1 can be roughly divided into a SECAM/PAL converter (SC) and a PAL (color signal) processor (PP>), and the circuits (1) to (8) in the converter (SC) are Both have the same configuration as in Figure 3, but the modulation circuit (6)
The first and second CW signals (C+) (Cz) supplied to the circuit use the output signal of a variable control oscillator, which will be described later, and its phase advanced by 90" using a 90° phase shift circuit (12). , the output line (2
1) and a direct connection line (2) to the input terminal (T) into which an SRCAM or PAL composite video signal can be introduced. ) PAL/S operates by obtaining the output signal of
It is configured to be switched by the output of the ECAM discrimination circuit (14).

On the other hand, the PAL processing unit (PP) includes a bandpass amplifier (15) for color signal extraction connected to the output line (42,) of the first switching circuit (13), and a color difference signal in the color signal. a gate circuit (16) that separates and derives the burst signal and the burst signal, an IH delay circuit (17) for separating R-Y and B-Y of the color difference signal, and an addition/subtraction circuit (IFi) (19).
), B-Y demodulation circuit 20) and R-Y demodulation circuit (21)
, color matrix circuit (22), 4.43M) Iz
variable controlled oscillator circuit (23), the first
30th W signal (C,) (Cri) (Cco is 90% higher than C1
@Proceeding. ), and a flip-flop (25) for driving this PAL switch (24), which can be used in conventional PAL receivers. It is the same as the thing.

Further, within this PAL processing unit (PP), a burst signal derived from the gate circuit (16) is transmitted to the oscillator (
The ACC and color killer circuit (26) operates by phase detection using the first CW signal (C2) from the gate circuit (25), and the burst signal from the gate circuit (16) is connected to the PAL switch (25).
The burst signal from the gate circuit (16) and the first CW signal (C+) is phase-detected by the ID circuit (27), which operates by phase-detecting the phase of the CW signal that has passed through the CW signal (C+). It is equipped with an APC circuit (28) that controls the phase of the variable control oscillator (23), and these are no different from conventional ones, but here they are characterized by the following configuration. A second switching circuit (29) operates between the control voltage from the APC circuit (28) and a constant DC voltage (Eo) according to the output of the PAL/SECAM discrimination circuit (14).
).

Next, to explain the operation of this embodiment, when receiving SECAM broadcasting, the second switching circuit (29) is first switched to the state shown in the figure by the output of the PAL/SECAM discriminating circuit (14), so the oscillation circuit (23) is It operates as a fixed frequency oscillator of 4.43MHz, and its constant phase tCW oscillator (
C1) is guided to the SECAM/PAL converter (SC),
This first CW signal (C+) and the second CW signal (C
2) is applied to the PAL phase modulation circuit (6). As a result, the output line (!2) of this modulation circuit (6) has sequentially phase-modulated R-Y and B-Y lines as shown in FIG. 2(A), just as in the case of FIG. I get a signal.

The modulated output signal (A) passes through the first switching circuit (13) in the illustrated state, is input to the bandpass filter (15) in the PAL processing section (PP), and is input to the gate circuit (16).
), the burst signal can be removed as the signal shown in FIG. 2 (E), and this signal (E) is input to the IH delay circuit (17) and addition/subtraction circuits (1g) (19). Therefore, the respective outputs become (FHG) (H) in Fig. 4, and the output signals (G) (H) of the addition/subtraction circuits (18) (19).
can be input to the B-Y demodulation circuit (20) and the R-Y demodulation circuit (21), respectively.

On the other hand, one of the demodulation circuits (20) is directly given the first cw (g (C+)) which matches the phase of the BY signal in the input signal (G) from the oscillation circuit (23).
This demodulation circuit (20) demodulates only the BY signal and removes the RY signal. Also, the other demodulation circuit (
21), the third CW signal (C3) (-C2) is applied to each IH so that the phase matches the phase of the RY signal in the input signal (H).
and its inverted output are alternately given from the PAL switch (24), so in this recovery circuit (21), the R-Y
Only the voice signal is demodulated, and the BY signal can be completely removed. Then, the demodulation circuits (20) and (21) obtain the B-Y signal and the R-Y signal, respectively, and obtain the demodulated signals from the matrix circuit (
22), the G-Y signal can be created.

Here, the ID circuit (27) is given the burst signal (21m(1)) separated by the gate circuit (16) and the CWg signal from the PAL switch (24), so this CW signal and the burst signal ( When the phase of the signal in the R-Y axis direction in I) is mismatched, the flip-flop (25)
, thereby stopping the reversing operation of the PAL switch (24
) is controlled so that the operating mode is normal, but such operation is basically the same as for PAL color symbols.

Also, in this state, as mentioned above, the oscillator (23) is operated by disconnecting the APC circuit (28), which means that the 1st vg2CWM signal obtained from this oscillator is
Since it is supplied as a carrier and a burst signal to the modulation circuit (6) in the AL converter (SC), when the APC circuit (28) is operated, the frequency fluctuation of the oscillation circuit (23) is accelerated. This is because the CW flaw signal frequency deviates significantly.

Also, when receiving PAL broadcasting, the PAL color composite video signal input to the input terminal (T) passes through the first switching circuit (13), which is in the opposite state as shown, to the bandpass amplifier (15).
), and a PAL color word of the type shown in FIG. 4<D) can be derived from this amplifier (15). Therefore, PAL
The processing section (PP) operates on the above-mentioned PAL color code, but since this operation is no different from the conventional one, the explanation will be omitted.

In addition, the ACC and color killer circuit (26) is SECA
When receiving M broadcasting, it operates in the same way as when receiving PAL broadcasting, and the ACC operation during SECAM is meaningless because it is based on the burst signal inserted on the receiver side. There is no particular need to stop during SECAM, so it is left as is.

Furthermore, in this embodiment, the third CW signal (Ca) directly obtained from the oscillator (23) is not used as the second CW signal supplied to the PAL phase modulation circuit (6), but the first CW signal (
C7) is passed through a 90° phase shift circuit (12) to create a second CW signal (C2) that has the same phase as the third CW signal (C3), but this is a SECAM/PAL signal.
If the conversion section (SC) and the PAL processing section (PP) are configured with separate IC chips, it is better to configure them in this way so that each IC has a terminal bin and a set of connecting leads between the bins. This is because you can save money.

(G) Effects of the Invention As described above, according to the present invention, the SECAM color code can be changed to
When configured to perform demodulation and reproduction using an AL color signal processing circuit, a CW oscillation circuit, an IH delay circuit, an addition/subtraction circuit, etc. are not required separately from those of the above PAL color signal processing circuit, and therefore 5ECA/PAL conversion is possible. This simplifies the configuration of the section, and especially when converting this section into an IC, the number of external parts and external pins can be reduced, and the configuration of the PAL color signal processing circuit itself does not need to be changed. The advantage is that conventional ICs can be used as is, and a dual-type television receiver can therefore be realized at low cost.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the main parts of an embodiment of the television receiver of the present invention, and FIG. 2 is a diagram showing the phase relationship of color signals in each part. FIG. 3 is a block diagram showing the main parts of a conventional SECAM/PAL conversion circuit, and FIG. 4 is a diagram showing the phase relationship of color signals in each part.

Claims (1)

[Claims] (1) In a PAL/SECAM dual type color television receiver that converts a SECAM color signal and demodulates it in a PAL color signal processing circuit for image reception, the SECAM color signal is directly demodulated and R-Y, B-
a demodulation circuit that outputs a Y-line sequential signal; and a demodulation circuit that performs phase modulation on the BY signal in the sequential signal using a first CW signal;
Further, the phase of the first CW signal is inverted and added as a burst signal, phase modulation is performed on the R-Y signal using a second CW signal having a phase different by 90 degrees from the first CW signal, and the second CW signal is added as a burst signal. a modulation circuit that operates to add a signal as a burst signal; a circuit that separates an input carrier color signal into a B-Y signal and a R-Y signal using an IH delay circuit and an addition/subtraction circuit; A PAL color signal processing circuit comprising a demodulation circuit that demodulates each B-Y signal, and a variable control oscillation circuit that supplies a CW signal to the demodulation circuit in the color signal processing circuit to fix a constant frequency when receiving SECAM broadcasting. A switching circuit that operates as an oscillator; and a circuit that derives the first and second CW signals from the oscillation circuit, and the color signal output from the modulation circuit is supplied as an input to the PAL color signal processing circuit. Color television receiver.