JPH01125191A - Video signal processor - 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 [Field of Industrial Application] The present invention uses a digital-to-analog conversion device to convert digital RGB data into a composite video signal (for example, NTSC system) for display on a CRT display device. The present invention relates to a video signal processing device for converting video signals.

[Conventional technology]

In recent years, in the field of personal computers or microcomputer systems, the display function of CRT display devices has become important due to the multifunctionality and diversification of game software or word processing software. On the other hand, in computers intended for widespread use in households, in order to configure the system at low cost, it is essential that a conventional television receiver can be used as a CRT display device.
Therefore, computer systems are required to use signal formats that can be received by conventional television receivers (NTSC in Japan).
format (PAL format in European countries). Furthermore, in order to realize the above-mentioned inexpensive computer system, it is currently necessary to integrate as many circuit components as possible into large-scale integrated circuits. Furthermore, in order to improve the degree of integration, the circuit must be implemented using MOS digital circuits.

However, since both the NTSC and PAL systems are extremely complex and highly accurate analog signals, high-quality composite video signals cannot be handled by MOS digital circuits.

[Problem that the invention seeks to solve]

Conventionally, in such video signal processing devices, it has been difficult to faithfully reproduce color information when converting digital RGB data into a composite video signal such as the NTSC system. The present invention provides a video signal processing device that can convert digital RGB data into a high-quality composite video signal and faithfully reproduce color information using a circuit configuration that can be easily realized with a MOS digital circuit. The purpose is to

[Means for solving problems]

The video signal processing device of the present invention converts RGB color data expressed in digital values into a luminance signal and two pigment signals expressed in digital values, and converts the luminance signal and two pigment signals.
a composite synchronization signal obtained by converting two color difference signals into analog values by a digital-to-analog conversion device, and combining the luminance signal expressed by the analog value, the two color difference signals, a horizontal synchronization signal, and a vertical synchronization signal; In an apparatus for obtaining a composite video signal which is formed by combining a color burst signal and a luminance signal expressed by the digital value, the - one of the two color difference signals expressed by the digital value and the digital It has means for converting three digital signals, a signal obtained by digitally adding color burst signals expressed as values, and the other color difference signal, into analog values by three independent digital-to-analog converters, and the analog Means capable of adjusting the output signal for each output of the three digital-to-analog converters to synthesize the luminance signal converted into a value, one color difference signal to which the color burst signal is added, and the other color difference signal. It is characterized in that the outputs of the three digital-to-analog converters are synthesized using the following.

〔Example〕

FIG. 1 shows a first embodiment of the present invention, and is a block diagram of a video signal processing device that generates an NTSC system composite video signal. 2.3.4 is an input terminal for digital ROB data, and 1 is a synchronization signal input terminal. 6 is a matrix conversion circuit, which converts the digital RGB input from 2.3.4.
The data is converted into a luminance signal (digital Y signal), a red difference signal (digital RY signal), and a blue difference signal (digital B-Y signal) expressed in digital values. 8 is a digital Y signal, 9 is a digital RY signal, and 10 is a digital BY signal. 11.12 is a balanced modulation circuit, which uses color subcarriers with different phase angles to convert the digital R-Y signal output from the matrix conversion circuit and the digital B-
The Y signal is balanced modulated. The control signal generation circuit 7 generates 21 digital color burst signals, and this signal is sent to the 22 digital adder circuit 10.
It is added to the digital BY signal of 1 and input to 12 balanced modulation circuits. Further, the control signal generation circuit 7 provides a control signal to the balanced modulation circuit 11.12 using the synchronization signal and the reference clock. Reference numeral 13 denotes a digital-to-analog converter, which converts the digital Y signal, the balanced modulated digital RY signal, and the balanced modulated digital signal by adding a digital color burst signal to the digital BY signal. , each is converted into an analog signal by an independent digital-to-analog converter. A synchronization signal is also input to the Y signal digital-to-analog conversion device, and the output signal is a Y signal containing the synchronization signal. 17
is a composite video signal synthesis circuit which combines the Y signal 14, the RY signal 15, and the B-Y signal burst signal 16, which have been converted into analog values, and outputs a composite video signal.

A specific circuit example of the composite video signal synthesis circuit 17 shown in FIG. 1 is shown in FIG. the Y signal converted to the analog value,
Input R-Y signal, B-Y signal child burst signal, 3
It is composed of 5 resistance elements and 37 transistors, and 3
A composite video signal is output to terminal 4.

FIG. 3 is a block diagram of a video signal processing device that generates a PAL composite video signal, which is a second embodiment of the present invention. FIG. 4 is a diagram showing a color burst in the PAL system and the phase relationship between two axes. In the PAL system, the phase of the color burst is selected to be ±135' from the B-Y axis as shown in Figure 4, corresponding to the switching of the phase of the color subcarrier of the R-Y signal. In the embodiment, the modulation axis is not the B-Y axis and the R-Y axis, but the fourth axis.
Two axes, A and B, shown in the figure are set. Therefore, the matrix conversion circuit 40 in FIG. 3 converts three digital R, G, and B data into three digital data of Y, A, and B. 41.42 is a balanced modulation circuit,
The 48 digital A signals and the 49 digital B signals output from the matrix conversion circuit are balanced-modulated using color subcarriers with different phase angles. A digital color burst signal is generated from the control signal generation circuit 44,
4 depending on the switching of the phase of the color subcarrier of the R-Y signal.
The digital color burst signal changeover switch No. 5 operates to select the A signal No. 48 or the B signal No. 49,
The signals are added through a 46.47 digital addition circuit. In FIG. 4, the color burst ■ on the A axis indicates that the digital color burst signal is added to the 48 digital A signals through the 46 digital adder circuits in FIG. There is. The control signal generation circuit No. 44 generates a color subcarrier having a phase difference of 90° in accordance with the switching of the phase of the color subcarrier of the R-Y signal.
1.42 is applied to a balanced modulation circuit. 13 is a digital-to-analog conversion device, which converts the digital Y signal, the balanced modulated digital A signal/burst signal (or A signal), and the balanced modulated digital B signal (or B signal);
The three signal burst signals) are converted into analog signals by independent digital-to-analog converters. A synchronization signal is also input to the Y signal digital-to-analog conversion device, and the output signal is a Y signal containing the synchronization signal. 43 is a composite video signal synthesis circuit;
The Y signal 14 converted into an analog value, the A signal child burst signal (or A signal) 52, and the B signal (or B signal child burst signal) 53 are combined to output a composite video signal.

According to the configuration described above, in the NTSC system, the Y signal, the R-Y signal, and the B-Y signal child burst signal are each independently digital-to-analog converted.
It is possible to obtain the R-Y axis and BY-axis with a phase angle of A high-quality composite video signal can be obtained. Similarly, in the PAL system, the Y signal, A signal child burst signal (or A signal), and B signal (or B signal child burst signal) are each independently digital-to-analog converted, resulting in a 90° phase difference. An angular A-axis and B-axis can be obtained, and the A-axis (or B-axis) is delayed by 180° relative to the phase of the color burst signal.
can be obtained accurately, resulting in a high-quality composite video signal.

In addition, with the configuration shown in Figure 2, by combining three analog signals and adjusting each resistance value, the phase and amplitude of each signal can be adjusted independently.
It is possible to adjust and correct the hue on the T-display.

〔Effect of the invention〕

As described above, according to the present invention, a luminance signal, one of two color difference signals, and a color burst signal expressed by a digital value are obtained by using a circuit configuration that can be easily realized with a MOS digital circuit. The signal obtained by digitally adding the
The other color difference signal is transmitted through three independent digital signals.
A high-quality composite video signal can be obtained by performing digital-to-analog conversion using analog conversion and combining with adjustable means (such as a resistor) to obtain a composite video signal. Furthermore, by adding the color burst signal to one of the two color difference signals, it is possible to accurately set the two color difference signal axes for the color burst.

Furthermore, it is possible to adjust and correct the hue, and has the effect of faithfully reproducing color information.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a video signal processing apparatus showing a first embodiment of the present invention, and FIG. 2 is a circuit diagram of an example of the composite video signal synthesis circuit shown in FIG. 17. Fig. 3 is a block diagram of a video signal processing device showing a second embodiment of the present invention, and Fig. 4 shows a color burst and a phase of two axes in the PAL system in this second embodiment. It is a diagram showing the relationship. 1... Synchronous signal input terminal 2... Digital R color data input terminal 3... Digital G color data input terminal 4... Digital B color data input terminal 5... Clock signal input terminal 6... Matrix conversion circuit 7...Control signal generation circuit 8...Digital Y signal 9...Digital R-Y signal 10...Digital B-Y signal 11...Digital balance modulation circuit 12...Digital balance Modulation circuit 13...Digital-to-analog converter 14...Analog Y signal 15...Analog RY signal 16...Analog B-Y signal + analog color burst signal 17...Composite video signal synthesis circuit 18...Composite video signal output terminal 19...R-Y balanced modulation carrier wave signal 20...B-Y+burst balanced modulation carrier wave signal 21...Digital burst signal 22...Digital addition circuit 31...・Analog Y data input terminal 32... Analog RY data input terminal 33... Analog BY data analog burst data input terminal 34... Composite video signal output terminal 35... Resistance element 36...・Capacitive element 37...npn type bipolar transistor 40...
Matrix conversion circuit 41...Digital balanced modulation circuit 42...Digital balanced modulation circuit 43...Composite video signal synthesis circuit 44...Control signal generation circuit 45...Digital color burst signal changeover switch 46...・Digital adder circuit 47...Digital adder circuit 48...Digital A signal 49...Digital B signal 50...A+burst (t- or A) balanced modulated carrier wave signal 51...B (or B + burst) balanced modulated carrier wave signal 52...Analog A signal + analog color burst signal (or analog A signal) 53...analog B signal (or analog B signal + analog color burst signal) Applicant: Seiko Epson Corporation Agent: Patent Attorney Tsumugi Mogami (1 other person) Figure 1 Figure 13

Claims (1)

[Claims] Convert RGB color data expressed in digital values into a luminance signal and two color difference signals expressed in digital values, and convert the luminance signal and two color difference signals into analog values by a digital-to-analog conversion device. and a composite synchronization signal composed of the luminance signal expressed by the analog value, the two color difference signals, the horizontal synchronization signal and the vertical synchronization signal,
In an apparatus for obtaining a composite video signal by combining a color burst signal, one of the luminance signal expressed by the digital value and two color difference signals expressed by the digital value, and one color difference signal and the digital value. and the other color difference signal are converted into analog values by three independent digital-to-analog converters, and the analog value is A luminance signal converted to , and one color difference signal to which a color burst signal is added,
The outputs of the three digital-to-analog converters are combined with the other color difference signal using a means capable of adjusting the output signal for each output of the three digital-to-analog converters. A video signal processing device.