JPH06105977B2 - Color signal processing circuit - Google Patents

Description

The present invention relates to a digital television device that performs signal processing after digitizing a video signal, and more particularly to a color signal processing circuit thereof.

(Prior Art) A remarkable advance in digital IC technology has made it possible to digitally perform baseband signal processing in a television receiver, which has been conventionally performed in analog. The advantage of digitizing the signal processing circuit is that in terms of performance, it is possible to perform high-precision, distortion-free processing peculiar to digital, and also to improve temperature change, time change, and noise performance, In terms of functionality, it can be connected to a memory or computer to facilitate multi-screen television, scanning speed conversion, still images, special effect processing, etc., and also facilitate connection with various new media signals that are digital signals. There are such things.

FIG. 6 shows a general structure of the digital video processing unit.
The analog video signal AV is output to the analog-digital converter 102.
Sampling and digitization are performed by and are converted into a digital video signal DV. Sampling is performed at the timing of the sampling pulse ΦS output from the voltage controlled crystal oscillator (hereinafter referred to as VCXO) 103. The frequency of the sampling pulse ΦS is four times the color subcarrier frequency f sc, and the phase is synchronized with the demodulation axis of the color signal.

The following description takes I and Q demodulation as an example. Therefore, the sample phases are ± I and ± Q phases in this case. The control of the sample phase is performed by the phase locked loop (PLL) circuit 106. The PLL circuit 106 calculates the sample phase in the color burst section of the input digital video signal DV,
A phase error signal S1 corresponding to the difference between this and the I and Q phases is output. The phase error signal S1 controls the oscillation frequency of the VCXO 103, whereby closed loop control is performed so that the phase of the sample pulse ΦS is synchronized with the I and Q phases. The sample pulse ΦS is supplied to each circuit as a reference clock in digital processing.

The digital video signal DV is a luminance / chromaticity separation circuit (hereinafter Y /
A C signal separation circuit) 108 separates the luminance signal Y1 and the color signal C. The luminance signal Y1 is subjected to contour, contrast, and bright adjustments in the luminance processing circuit 112, and then,
It is newly output as the luminance signal Y2. The color signal C is subjected to automatic saturation control (ACC), color saturation adjustment, hue adjustment, color demodulation, and matrix calculation processing in the color signal processing circuit 113, and three color difference signals (RY) and (G-Y). ), (B-
Y) signals are converted and output. The timing signal S2 necessary for the processing here is input from the PLL circuit 106. Color difference signals (R-Y), (G-Y), (B-Y)
Is added to the luminance signal Y2 in the adders 121, 122, 123 and output as color signals R, G, B. These signals, after being digital-analog converted, drive the color cathode ray tube through the output circuit. Also, the controller 12
An image quality adjustment signal 125 controlled by the viewer and a signal 126 sent from the digital processing unit to the controller 124, which is necessary for various automatic controls, are input to the unit 4. The controller 124 processes the input signals 125 and 126 based on a predetermined program,
The signal processing parameter 127 is output to each circuit of the digital processing unit.

The above is the outline of the entire digital processing unit. Next, the color signal processing circuit 113 will be described.

FIG. 7 shows a conventional color signal processing circuit 113. Y / C
The color signal C from the separation circuit 108 is supplied to the multiplier 201 by the ACC signal A2.
Is multiplied by. The output signal C1 of the multiplier 201 is the ACC circuit 203.
Entered in. Here, the amplitude of the color burst is detected, and the magnitude of the ACC signal A2 is controlled so that it approaches a predetermined target value. As a result, the amplitude change of the color signal C due to the characteristics of the transmission path from the transmission station to the receiver is corrected.

A burst flag pulse (BFP) indicating the position of the color burst is input to the ACC circuit 203 to set the ACC operation timing. The output of the multiplier 201 is input to the data latch circuits 205 and 206. The data latch circuit 205 extracts I phase data from the input signal C1 and demodulates the I signal (ID). The timing of data extraction is given by the pulse ΦI. Similarly, the data latch circuit 206
Then, the Q phase data is extracted by the pulse ΦQ,
The signal (QD) is demodulated. The pulses ΦI and ΦQ are generated by the timing circuit 207 based on the color demodulation pulse ΦC. The color demodulation pulse ΦC is output from the PLL circuit 106 together with the burst flag pulse (BFP), and is a pulse that always gives a constant phase timing (for example, Q phase).

The demodulated I signal (ID) and Q signal (QD) are color adjustment circuits.
Input to 217. Here, the sine signal (A1sinθ) input from the controller 124 and the cosine signal (A1cos)
θ) is used to adjust the color saturation and the hue. The signals (A1sinθ) and (A1cosθ) are the controller 12 based on the color saturation signal A1 and the hue signal θ controlled by the viewer.
4 calculates (A1sinθ), (A1cos
θ). The color adjustment circuit 217 receives the input I,
The Q signal is subjected to gain adjustment and coordinate rotation calculation as shown in the following equations to obtain the output I'signal (I'D) and Q'signal (Q'D).

In other words, compared to the input, the output has a color depth of A1 times,
The hue will change by θ. I'signal (I '
D) and Q'signal (Q'D) are applied to the multipliers 221 to 226 and the adder.
By the matrix operation shown in the following formula in 227 to 229,
The color difference signals (R-Y), (G-Y), and (B-Y) are converted.

The matrix coefficients (RI, RQ, GI, GQ, BI, BQ) are given from the controller 124. This value is not always a theoretically constant value and must be changed according to the characteristics of the color cathode ray tube used.

(Problems to be Solved by the Invention) In the conventional color signal processing method described above, at least nine multipliers are required for ACC processing, color saturation / hue adjustment, and matrix calculation. The circuit scale of the multiplier is
As is well known, it is a large amount, and for example, in the case of (8 × 8) bits, it reaches about 1000 gates. This becomes a serious problem in making the system IC. In particular, matrix calculation requires a large number of circuits. However, digitizing this makes it easy to connect to externally input digital RGB signals, and also reduces many external parts required for analog matrix circuits, which is a great advantage. Therefore, it has been strongly desired to reduce the circuit amount in the matrix circuit.

Therefore, an object of the present invention is to provide a color signal processing circuit capable of significantly reducing the number of high speed multipliers required for color signal processing (ACC, color saturation / hue adjustment, matrix operation).

[Structure of the Invention] (Means for Solving the Problem) The present invention, after digitizing an analog video signal,
In a digital television device that performs signal processing, a plurality of color signal components separated from a digital video signal and having different modulation axes are time-division-multiplexed, and a plurality of color signal components for correcting each color signal component Multiplication means for multiplying the matrix coefficient by time division and outputting the result,
Adding means for sequentially outputting a plurality of different color difference signals corresponding to the plurality of matrix coefficients by adding a corrected output signal obtained by the multiplying means and a signal obtained by delaying the corrected output signal by a predetermined time; And an output means for separating and extracting the plurality of different color difference signals obtained by the adding means by demodulation pulses at respective color difference signal timings.

(Operation) By the above means, the color saturation adjustment and the hue adjustment to the color difference signal conversion can be performed by one system, and the matrix calculation for multiplying a plurality of color difference signals in parallel is unnecessary.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. The color signal C from the Y / C separation circuit is input to the multiplier 300, and the data selector 3
It is multiplied with 10 output signals K3. The matrix coefficient (RI, RQ, GI, GQ, BI, BQ) output from the controller 304 and the ACC signal A2 output from the ACC circuit 303 are output to the data selector 310 as data. A burst flag pulse (BFP) and a matrix coefficient selection signal K4 are used as select signals for selecting one of these seven input signals.

FIG. 2 is a timing chart for explaining the operation of the circuit of FIG.

During the color burst period, the data selector 310
CC signal A2 is output. This is switched at the timing of the burst flag pulse (BFP), and FIG. 2 (A) shows the timing relationship. In other words, during the color burst period, ACC operation has the highest priority,
During this period, the ACC circuit 303 detects the amplitude of the color burst, and the ACC signal A2 is set so as to bring it close to the predetermined target value.
Is controlling the size of. In the periods other than the color burst period, the matrix coefficients (RQ to BI) are derived as the output signal K3 at the timing shown in FIG. 2 (B). As a result, when the phase of the color signal C is ± Q, ± R
For Q, ± GQ, ± BQ, and ± I phases, ± RI, ± GI, and ± BI are cyclically selected and output. As a result, as the output signal C2 of the multiplier 300, as shown in FIG. 2B, Q.RQ, I.RI, Q.GQ, I.GI, Q.BQ, I.BI.
Are sequentially obtained.

The matrix operation is Therefore, if the sum of the signal C2 and the signal C3 obtained by delaying the signal C2 by one sample is realized by the latch circuit 301 and the adder 302, the addition output C4 becomes 1 as shown in FIG. 2 (B). Color difference signals of (RY), (GY), and (BY) are obtained for each sample.

Therefore, in order to demodulate the color difference signal (RY) from this signal, the latch operation may be performed by the latch circuit 307 by the (RY) pulse ΦR. Color difference signals (G-Y), (B-
Similarly, for Y), the latch operation may be performed in the latch circuits 308 and 309 by using the pulse ΦG for G-Y and the pulse ΦB for BY.

The color difference signals (R-Y), (G-Y), and (B-Y) are latched every 6 samples, which is 2.4MHz when converted to frequency.
Becomes This is a value that does not cause any practical problem even if the sampling theorem and the band of the color signal are taken into consideration.

On the other hand, the controller 304 sends the ACC signal A2 from the ACC circuit 303.
Then, the color saturation signal A1 and the hue signal θ controlled by the viewer are input. Further, in the internal memory of the controller 304, reference matrix coefficients (RI0, RQ0, GI0, GQ0, BI0, BQ0) determined by the characteristics of the color cathode ray tube are stored, and the matrix coefficients (RI, RQ ,
GI, GQ, BI, BQ) is calculated as follows.

That is, the matrix coefficient (RI,
RQ, GI, GQ, BI, BQ) is the calculation of ACC, color saturation, and hue. Therefore, the demodulated color difference signals (RY), (GY), and (BY) do not require subsequent color processing.

The embodiment of FIG. 1 has been described above. Next, the timing circuit 311 and the data selector 310 will be described in more detail.

The relationship between the color signal C and the output signal K3 of the data selector 310 is shown in FIG. 2 (B). It is the timing generation circuit 311 that actually controls this relationship.

FIG. 3 shows a detailed embodiment of the timing generation circuit 311 and the data selector 310, and FIG. 4 shows a timing chart for explaining these operations.

In FIG. 3, the selection circuit 5 inside the data selector 310 is shown.
15 is controlled by burst flag pulse (BFP)
In the color burst period, the ACC signal A2 is selected, and in the other periods, the matrix signal MTX is selected as the output signal K3 and is output to the multiplier 300. The matrix circuit MTX is
As shown in FIG. 4 (g), one cycle is formed by 12 samples including the code in relation to the color signal C. Therefore, 12 types of coefficients are input to the data selector 513 that outputs the matrix signal MTX by using an inverter so that matrix coefficients of both positive and negative signs can be input. And
The data selector 513 outputs one by one according to the matrix coefficient selection signal SEL. The matrix coefficient selection signal SEL is generated from the color demodulation pulse ΦC and the sample pulse ΦS which give the -Q phase from the PLL circuit 106. On the other hand, color difference signals (R-Y), (G-Y), (B-
Latch pulse ΦR, ΦG, ΦB for demodulating Y)
Is a color demodulation pulse ΦC delayed for a predetermined time. That is, the timing generation circuit 311 is provided with counters 501 and 504 for producing the matrix coefficient selection signal SEL, an AND circuit 503, and a latch circuit 507. The latch circuit 507 and the latch circuits 508 to 512 are connected in cascade, and are used to generate latch pulses ΦB, ΦG, and ΦR for color demodulation.

The sample pulse ΦS in FIG. 4 is used as a clock for the latch circuits 507 to 512 and also as a clock for the counter 504. Also, color demodulation pulse ΦC
Is used as a data input to the latch circuit 507 and is also used as a clock for the counter 501.

4A to 4D show the contents of the sample pulse ΦS, the color signal C, the color demodulation pulse ΦC, and the output DN of the counter 501. Further, FIG. 4E shows an output pulse T1 of the AND circuit 503, which is given to the clear terminal of the counter 504. Therefore, the counter 504 obtains the matrix coefficient selection signal SEL obtained by converting the sample pulse ΦS in binary. On the other hand, the latch circuits 508, 510, 512
As shown in FIGS. 4 (h), (i), and (j), latch pulses .PHI.B, .PHI.G, and .PHI.R for demodulation are obtained from the respective output terminals of.

The circuit configuration of this embodiment described above can be realized with about 200 gates, and the easiness of manufacturing the circuit and the reduction of the cost can be obtained. That is, with the conventional circuit configuration, 9
Although the number of multipliers required by hardware was calculated, by multiplying the matrix coefficient prepared by computing the necessary multipliers in advance and the digital color signal in which the biaxial components are sequentially arranged by digitization. , The number of multipliers can be greatly reduced.

In the above-described embodiment, in order to reduce the number of multipliers used as hardware, when the matrix coefficient that is actually multiplied by the color signal C is preprocessed, it is performed by the controller 304 as software. explained. However, the method is not limited to this, and the function may be shared with the hardware according to the processing capability of the software, and various modifications and applications are possible as this mode.

For example, a coordinate rotation matrix for changing the hue as a factor that complicates the calculation in Expression (1). There is. Therefore, the hue adjustment can reduce the processing load of software by using the method of changing the sample phase at the time of analog-digital conversion. The calculation in the controller 304 in this case is Good.

Further, among the signals included in the equation (1), all the signals other than the ACC signal A2 are fixed values or semi-fixed values adjusted by the viewer according to his / her preference. Therefore, the multiplication of the ACC signal A2 can be shared by the hardware side to reduce the speed limitation on the software processing side. The circuit configuration in this case is as shown in FIG.

The difference between the circuit of FIG. 5 and the circuit of FIG. 1 is that a multiplier 701 for multiplying the output K3 of the data selector 310 and the ACC signal A2 is added. Then, the output K5 of the multiplier 701 is input to the multiplier 300. At this time, the ACC signal A2 is not input to the controller 304 and is directly multiplied by the matrix signal K3 in hardware. Therefore, the controller 304 may perform the following calculation.

During the color burst period, "1" appears at the output K3, and during this period, the color signal C is multiplied by the ACC signal A2, and the automatic color signal gain control is preferentially performed.

As described above, according to the present invention, color signal processing (AC
C, color saturation / hue adjustment, matrix operation), which can significantly reduce the number of multipliers that increase the circuit scale, and can simplify the entire circuit, which is advantageous for integration. It is possible to obtain various circuits.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a timing diagram shown for explaining the operation of the circuit of FIG. 1, and FIG. 3 is a circuit showing a part of FIG. 1 in more detail. 4 and 5 are timing charts for explaining the operation of the circuit of FIG. 3, FIG. 5 is a circuit diagram showing another embodiment of the present invention, and FIG. 6 is a digital video signal processing circuit. FIG. 7 is a circuit diagram showing a conventional color signal processing circuit. 300, 700 ... Multiplier, 301, 307, 308, 309 ... Latch circuit, 302 ... Adder, 303 ... ACC circuit, 304 ... Controller, 310 ... Data selector, 311 ... Timing generation circuit.

Claims (1)

[Claims] 1. After digitizing an analog video signal,
In a digital television device that performs signal processing, a plurality of color signal components separated from a digital video signal and having different modulation axes are time-division-multiplexed, and a plurality of color signal components for correcting each color signal component Multiplying means for multiplying the matrix coefficient by time division and outputting the result, and adding the correction output signal obtained by the multiplying means and the signal obtained by delaying the correction output signal for a predetermined time to obtain the plurality of matrix coefficients. And adding means for sequentially outputting a plurality of different color difference signals according to the above, and output means for separating and extracting the plurality of different color difference signals obtained by the adding means by demodulation pulses at respective color difference signal timings. A color signal processing circuit characterized by the above.