JPS62165497A - color demodulation circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a color demodulation circuit in a SECAM type television receiver.

[Prior art and its problems] One of the color television systems is the SECAM system. This SECAM method uses two color difference signals, namely R
A signal proportional to -YS8-Y is frequency-modulated and transmitted line-sequentially, and on the reception (*8m side, a horizontal one-line delay line is used to convert the sequential signals into simultaneous signals and demodulate them.

A color demodulation circuit for a television receiver in the SECAM system has conventionally been constructed as shown in FIG. In other words, the SECAM color demodulation circuit consists of video chroma signal processing ■C1, controller 2,
Chroma trap 3, chroma band pass filters 4 and 1
It is constituted by an H delay line 15, and a video signal sent from a previous-stage video amplification circuit (not shown) is inputted to a video chroma signal processing unit C1 via a chroma trap 3 and a chroma bandpass filter 4. This video
The Oma signal processing ICI includes a Y amplifier 5 for luminance signal amplification,
Discrimination circuit 6, limiter amplifier 7, SECAM switch 8
, G-Y matrix circuit 9, R-Y detection circuit 10, B
- It consists of a Y detection circuit 11, an R matrix circuit 12, a G matrix circuit 13, and a B matrix circuit 14, and a 1H delay line 15 is externally connected. As the 1H delay line 15, for example, a glass delay line is used. Then, the luminance signal Y output from the chroma trap 3 is passed through the Y amplifier 5 to the R matrix circuit 12,
The signal is input to a G matrix circuit 13 and a B matrix circuit 14. Further, the limiter amplifier 7 receives the O signal C output from the chroma band pass filter 4, and the discrimination circuit 6 receives the line discrimination signal 1-ID sent from the control section (not shown). be done.

This line discrimination signal HD is a signal in which a 1H (one horizontal period) width signal is alternately inverted to ``1 level'' or ``10 degrees'' level. The discrimination circuit 6 has a line discrimination signal HD.
The signal level is determined and the SECAM switch 8 is switched to the a contact or b contact side. The SECAM switch 8 consists of a first switch 8a and a second switch 8b, and the a contact of the first switch 8a and the b contact of the second switch 8b.
The output of limiter amplifier 7 is connected to the 1H delay line 1 at the contact point.
5. Further, the output of the limiter amplifier 1 is directly input to the b contact of the first switch 8a and the a contact of the second switch 8b. Then, the first switch 8a
The signal selected by R
The signal sent to the matrix circuit 12 and the G-Y matrix circuit 9 and selected by the second switch 8b is sent to the B-matrix circuit 14 and the G-Y matrix circuit 9 via the B-Y detection circuit 11. -Y matrix circuit 9
The output of is sent to the G matrix circuit 13. However,
The above R matrix circuit 12, G matrix circuit 13, B
Color signals R, G output from the matrix circuit 14,
B is input to A/D converters 16 to 18 in the controller 2, respectively. Further, a clock generation circuit 19 is provided in the controller 2, and a clock outputted from this clock generation circuit 19 is transmitted to the A/D converters 16 to 1.
8 as a sampling clock. Above A/D
The converters 16 to 18 convert the color signals R, G, and B sent from the video chroma signal processing ICI into 4-pit digital signals DR1 to DR4, DG1 to DG4, respectively.
The data is converted into DB1 to DB084 and output to the next stage display section (not shown).

In the above configuration, from the video signal sent from the video amplifier circuit, the luminance signal Y is extracted by the chroma trap 3, and after being amplified and peaked by the Y amplifier 5, the R matrix circuit 12, the G matrix circuit 13, The signal is sent to the B matrix circuit 14. Further, the chroma signal C output from the chroma bandpass filter 4 is limiter amplified by the limiter amplifier 7 and then sent directly or via the 1H delay line 15 to the SECAM switch 8.
is input. This SECAM switch 8 is switched and controlled by the discrimination circuit 6, and is switched to the a contact side at the timing when the B-Y signal is output from the limiter amplifier 7, and the R-YM signal is output from the limiter amplifier 7. At the timing, it is switched to the b contact side. Therefore, when the B-Y signal is output from the limiter amplifier 7 at a certain timing, the R-Y signal extended by 1Hil by the 1H delay line 15 is input to the R-Y detection circuit 10.
A BY signal output from the limiter amplifier 7 is input to the BY detection circuit 11 . Also, if the R-Y signal is output from the limiter amplifier 7 at the following timing,
The RY signal outputted from the limiter amplifier 7 is input as is to the RY detection circuit 10.

The 8-Y signal delayed by the 1H delay line 15 is input to the 8-Y detection circuit 11 . In the SECAM system, the R-Y signal and the B-Y signal are transmitted alternately, but as described above, by switching the SECAM switch 8 according to the line discrimination signal, the R-Y detection circuit 10 receives the R-Y signal.
Also, the BY signal is always input to the BY detection circuit 11, and the RY signal and the BY signal are demodulated.

Then, the R-Y detection circuit 10 and the B-Y detection circuit 11
The R-Y signal and B-Y signal demodulated by are sent to the G-Y matrix circuit 9 to create a G-Y signal.

After that, the above R-Y signal, G-Y signal, and B-Y signal are
The signal is sent to the R matrix circuit 12, the G matrix circuit 13, and the B matrix circuit 14, and is added to the luminance signal Y to obtain primary color signals @R, G, and B. These primary color signals R, G, and B are sent to the controller 2, converted into digital signals by A/D converters 16 to 18, and sent to the display section.

As can be seen from the above operation description, in the SECAM system, the R-Y and B-Y color difference signals are transmitted alternately every 1H, and therefore the 1H delay line 15 is used to transmit the R-Y and B-Y color difference signals during each H period. -Y and R-B signals are simultaneously present to synthesize the G-Y signal. As mentioned above, in the conventional SECAM method, R-Y,
A 1H delay line 15 is required to synthesize the G-Y signal from the B-Y signal, and for small TVs such as LCD TVs, the 1H delay line is expensive and large in size, making it difficult to miniaturize the product. It was a big obstacle.

[Object of the Invention] The present invention has been made in view of the above points, and is an SE that can perform color demodulation without using a 1H delay line.
The object of the present invention is to provide a color demodulation circuit for a small CAM type television.

[Summary of the Invention] The present invention provides a 1H shift register in the controller LSI in the color demodulation circuit of a SECAM television receiver, and A By processing digital signals after /D conversion, color demodulation processing can be performed without using a 1H delay line.

Embodiment 1 of the Invention Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The color demodulation circuit according to the present invention is a SECA circuit as shown in FIG.
It is composed of an M-type video chroma signal processing ICIA, a controller LS 12A, a chroma trap 3, and a chroma bandpass filter 4, and the video amplification circuit (
A video signal sent from a video chroma signal processing IC+A (not shown) is inputted to a video chroma signal processing IC+A via an O madrub 3 and a chroma bandpass filter 4. This video chroma signal processing IC 1A includes a luminance signal amplification Y amplifier 5, a discrimination circuit 6, a limiter amplifier 7, and a SECAM switch 8.
, RY detection circuit 10. The B-Y detection circuit 11 is buzzing. Then, the luminance signal Y output from the chroma trap 3 is amplified by the Y amplifier 5 and the controller L
Sent to S 12 A.

Further, the chroma signal C output from the chroma bandpass filter 4 is input to the limiter amplifier 7, and the discriminator circuit 6
A line discrimination signal HD sent from a control section (not shown) is input to the control section. The discrimination circuit 6 discriminates the signal level of the line discrimination signal HD, and the SECAM switch 8
is switched to the A contact or B contact side, and the switching signal is used as the IQ output to the controller LS12.
Output to A. The SECAM switch 8 consists of a first switch 8a and a second switch 8b, and switches the output signal of the limiter amplifier 7 by the first switch 8a to
The signal is input to the Y detection circuit 10 or the BY detection circuit 11. Then, the R-Y detection circuit 10 and the B-Y detection circuit 11
The output signals of are alternately selected and extracted by the second switch 8b and output to the controller LSI2A.

The controller LS 12 A includes an A/D converter 20
．． 21, G-Y matrix circuit 22.1H shift register 23, R matrix adder 24, G matrix adder 25, B matrix adder 26, the clock pulse output from the clock generation circuit 19 is sent to the circuit. And video chroma signal processing ICI
R-Y sent via SECAM switch 8 of A
The M@ and BY signals are input to the A/D converter 20, and the Y
A signal sent from the amplifier 5 is input to the A/D converter 21. The A/D converter 20 converts the color difference signal sent from the video chroma signal processing ICIA into a digital signal, and sends it directly to the G-Y matrix circuit 22 and 1H.
Input via shift register 23. The G-Y matrix circuit 22 separates the R-Y signal and the B-Y signal, and also combines the G-Y signals, and sends the R-Y signal to an adder 24 for R matrix and the G-Y signal for G matrix adder 25,
The B-Y signals are output to the B matrix adder 26, respectively. Further, the A/D converter 21 converts the luminance signal @Y sent from the video/chroma signal processing IC 1A into a digital signal and outputs the digital signal to the adders 24-26. Adders 24 to 26 add the color difference signal from the G-Y matrix circuit 22 and the luminance signal from the A/D converter 21, and produce 4-bit digital signals DR1 to DR4, DG1 to DG4,
The signals are outputted to the next display section (not shown) as D81 to DB4.

Next, the operation of the above embodiment will be explained. From the video signal sent from the video amplification circuit, a brightness signal Y is extracted by the amplifier 3, amplified and peaked by the Y amplifier 5, and then sent to the A/D in the controller LS 12A.
The signal is sent to the converter 21. Further, the chroma signal C output from the chroma bandpass filter 4 is transmitted to the limiter amplifier 7.
After being amplified by the limiter, the signal is sent to the RY detection circuit 10 or the BY detection circuit 11 via the first switch 8a of the SECAM switch 8. At this time, the discrimination circuit 6 switches the SECAM switch 8 to the a-contact or b-contact side every 1H according to the line discrimination signal HD. That is, the discrimination circuit 6 switches the SECAM switch 8 to the a contact side when the R-Y signal is being sent, and switches the SECAM switch 8 to the b contact side when the B-Y signal is being sent. Switch to Therefore, when the RY signal is output from the limiter amplifier 7 at a certain timing, this RY signal is sent to the RY detection circuit 10 via the first switch 8a, and further to the RY detection circuit 10. 10 and is sent to the A/D converter 20 via the second switch 8b. Then, when the B-Y signal is output from the limiter amplifier 7 at the next timing, this B-Y signal is sent to the B-Y detection circuit 11 via the first switch 8a, and further to this 8-Y detection circuit. The second A/D converter 20 from No. 11 receives the R-Y signal and the B- signal given at different timings as described above.
Convert each Y signal to a 4-bit digital signal and
-Y matrix circuit 22, and is also delayed by 1H by 1H shift register 23 and input to GY matrix circuit 22. The G-Y matrix circuit 22 transfers the digitally converted input R-Y signal and B-Y signal to the R matrix adder 24 and the B matrix adder B2G, and also transfers the R-Y signal and the B-Y signal to the R matrix adder 24 and the B matrix adder B2G. A G-Y signal is synthesized from the -Y signal and output to the G matrix adder 25. As mentioned above, at the timing when the A/D converter 20 outputs the R-Y signal, the 1H shift register 23 outputs the B-Y signal delayed by 1H, and the A/D converter 20 outputs the B-Y signal. 1H at the timing when is output
The shift register 23 outputs the R-Y signal delayed by 1H, and the R-Y signal and the B-Y signal are simultaneously given to the G-Y matrix circuit 22, so the G-Y matrix circuit 22 receives the R-Y and B- A G-Y signal can be synthesized from Y's two-person power signals. In this case, the G-Y matrix circuit 22 is subjected to 1116D by the 10 clocks sent from the discrimination circuit 6 and the clock pulses output from the clock generation circuit 19, and performs the following calculation to create the G-Y signal.

(G-Y) -0,51 (R-Y) +0.19 (B-Y) As described above, from the G-Y matrix circuit 22 to R-Y
A signal, a G-Y signal, and an 8-Y signal are obtained, and the adder 24~
Sent to 26. The adders 24 to 26 are connected to R-Y, G-Y, B-Y output from the G-Y matrix circuit 22.
The color difference signal and the luminance signal output from the A/D converter 21 are added to generate R, G, and B primary color digital signals OR1 to D.
R4, DGI to DG4, and DB1 to D84, and drive the display section of the next stage.

[Effects of the Invention] As detailed above, according to the present invention, a 1H shift register is provided in the controller and SI in the color demodulation circuit of a small TV using the SECAM system, and the processing that was conventionally performed using a video chroma signal processing IC is implemented. Since R, G, and 8 matrix processing is processed using digital signals after A/D conversion, color demodulation can be performed using a 1H shift register instead of a 1H delay line, and an external 1H delay line can be used for color demodulation.
It is possible to simplify the manufacturing process by eliminating the need for a delay line, and also to reduce the size and cost.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a color AM circuit according to an embodiment of the present invention, and FIG. 2 is a block diagram showing the configuration of a conventional color demodulation circuit. 1.1A...Video chroma signal processing IC12, 2A
...Controller LSI, 3...Chroma trap,
4... Chroma band pass filter, 5... Y amplifier for luminance signal amplification, 6... Discrimination circuit, 1... Limiter amplifier, 8... SECAM switch, 9... G-Y
Matrix circuit, 10...RY detection circuit, 11...
・B-Y detection circuit, 12...R matrix circuit, 13
...076992 circuit, 14...B matrix circuit, 15...1H delay line, 16-18...A
/D converter, 19... Re-O-sock generation circuit, 20...
A/D converter, 21...A/D converter, 22...G
-Y matrix circuit, 23...1H shift register,
24... R matrix filter, 25... G matrix adder, 26... B matrix adder.

Claims (1)

[Claims] In the color demodulation circuit of the SECAM system television receiver, the R-Y detection circuit and the B-Y detection circuit detect the R-Y signal and the B-Y signal in the chroma signal, respectively, and the R-Y detection circuit described above.
- switch means for alternately taking out the color difference signals of the RY signal and the BY signal outputted from the Y detection circuit and the BY detection circuit every 1H according to the line discrimination signal; An A/D converter that sequentially converts color difference signals into digital signals, a 1H shift register that delays the output signal of this A/D converter by 1H, and outputs the output signal of this 1H
The output signals of the shift register and the A/D converter are input, the R-Y signal and the BY signal are separated and output, and the G-Y signal is synthesized from the R-Y signal and the BY signal. A G-Y matrix circuit that outputs the digital signal, and a luminance signal A/D that converts the luminance signal in the video signal into a digital signal.
The converter, this luminance signal A/D converter, and each color difference signal output from the G-Y matrix circuit are added and R
, G, and B primary color digital signals.