JPH0265589A - Rgb matrix circuit - Google Patents

Abstract

PURPOSE:To obtain ease to see character or the like subjected to superimposition by converting a color difference signal into a primary color signal, inputting an RGB interface circuit corresponding to each primary color signal and providing a half tone function simultaneously. CONSTITUTION:A color difference signal Vi and a luminance signal Vy outputted from a video/chroma circuit 6 are inputted to a transistor(TR) Q1 via resistors R2, R3 respectively, subjected to matrix processing into a primary color signal and the signal is outputted from a collector of the said TR Q1. A resistor R1 is connected in parallel with a resistor R4 via a diode D1 and a TR Q2. In the case of displaying a teletext broadcast or the like, when a half tone control signal outputted from a microcomputer or the like being at an H level is fed to a terminal 10, a common base TR Q5 is turned on, the resistors R4, R1 are connected in parallel equivalently and the gain of the TR Q1 is selected properly by selecting the resistance of the resistor R1. Thus, the degree of half tone is decided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an RGB matrix circuit that obtains primary color signals from color difference signals and luminance signals, and relates to a circuit having a halftone function.

[Prior Art] In a video circuit such as a television receiver, the color difference signals R-Y, G-Y, B-Y and the luminance signal -Y (or RGB primary color signals) from the video/chroma circuit 1 are as shown in FIG. (RG
As shown in (showing the case of B primary color signal), the video output circuit 2 amplifies it to a predetermined level and then adds it to the CRT 3. In recent years, however, with the increase in fit, switching with abundant external video input, or superimposition For this purpose, as shown in FIG. 5, an RGB interface circuit is provided between the video/chroma circuit I and the video output circuit 2! 4 is now being inserted.

[Problems to be Solved by the Invention] However, the ROB interface circuit 4 includes one that supports color difference signals and one that supports primary color signals, and a color difference signal cannot be input to the one that supports primary color signals.

The present invention converts a color difference signal into a primary color signal and inputs it to the RGB interface circuit 4 compatible with primary color signals,
At the same time, an RGB matrix circuit 5 having a halftone function is provided.

[Means for Solving the Problems] To this end, the present invention provides an RGB matrix circuit that inputs a color difference signal and a luminance signal to generate a primary color signal.
A first transistor for a matrix, which applies the above-mentioned color difference signal and luminance signal to the base and emitter, respectively, is made into a monochromatic part, and is connected to the output of the first transistor via a diode and a resistor for gain control. a second transistor coupled to the base of the second transistor;
The second transistor is switched based on the halftone control signal, and the gain control resistor is connected in parallel to the load resistor of the first transistor.
A GB matrix circuit was constructed.

[If a color difference signal is output from the video/chroma circuit,
By means of the present invention, it is possible to convert the same color difference signal into a primary color signal and input it to the ROB interface circuit, so it is possible to handle both color difference signals and primary color signals using an RGB interface circuit that supports primary color signals. , and can have a halftone function.

C Example Examples of the present invention will be described below.

In FIG. 2, the color difference signal Vi and the luminance signal vy output from the video/chroma circuit 6 are respectively input to the transistor Ql via the resistor R2R3, processed in a matrix and made into a primary color signal, which is output from the collector of the transistor Q). do.

If the output signal of transistor Ql is vO, then Vo=
" (Vi - Vbe - Vy) + Vee, so if the input signals (Vi, Vy) are constant, the output signal Vo is determined by the ratio of the resistors R2 and R4.

Therefore, in parallel with resistor R4, diode DI.

If the resistor R7 is connected through the transistor Q2, when the halftone control signal output from the microcomputer etc. when displaying teletext etc. reaches the rH level and is applied to the terminal 10, the base-grounded transistor Q5 is connected. is turned on, and the on-current flows through the resistor R6 to the base of the halftone control transistor Q2, turning on the transistor Q2, so that the resistor R4 and the resistor R1 are equivalently connected in parallel. By selecting the value of the resistor R7, the gain of the transistor Q/ can be appropriately selected, and therefore the degree of halftone can be determined.

The halftone control signal is at "H" level or rl-=OVJ
It is a level digital signal.

Transistors Q2 and Q5 and resistors R5 to R8 constitute a halftone control circuit that is common to the three RGB colors. Terminals II and 12 are connected to transistors for each color matrix via gain control resistors R12 and RI3.

Resistors R5 to R8 have halftone control signal level r)
(The value is set so that the transistor Q2 turns on sufficiently when the voltage becomes J.

Figure 3 shows a circuit configured to compensate for fluctuations in signal level due to temperature. The primary color signal processed by matrix processing using a transistor Ql (P#7') and output to the collector is connected to a resistor RIO to the collector and a resistor R9 to the emitter. It consists of a temperature-compensating MP transistor Q3 whose base is connected to the collector of the transistor Q/, and a PNP transistor Q4 having an emitter follower configuration whose base is connected to the collector of the transistor Q3.

By setting the emitter resistance R9 and the collector resistance RIO of the transistor Q3 in the same circuit to substantially the same value, temperature compensation of the signal level of the ROB matrix circuit including the output stage formed by the transistor Q4 can be performed. be.

The primary color signal output from the transistor Q4 is connected to the terminal 9.
It is outputted through a video output amplifier, etc., and connected to a CRT, where it is displayed as an image.

In Figure 1, the circuits in Figures 2 and 3 described above are combined, and the color difference signal R-Y is input to terminal 7, the luminance signal -Y is input to terminal 8, and the signal level is halftone from terminal 9. Figure 3 is a circuit diagram of one color portion of an RGB matrix circuit including a shared halftone control circuit portion for G and B signals to obtain a controlled and temperature compensated R signal;

[Effects of the Invention From the above, according to the RGB matrix circuit of the present invention,
Not only can primary color signals be obtained from color difference signals, but halftone processing can also be performed by controlling the gain setting resistor connected to the transistor for the matrix, so the contrast of the image on the screen can be adjusted. It is possible to make the superimposed characters easier to see by lowering the value to create a halftone image.Also, even if superimposition is not used, halftone images can be used to reduce power consumption.

Further, a third transistor whose emitter resistance and collector resistance are substantially the same value, and a fourth output transistor whose base is connected to the output of the third transistor are connected to the output of the transistor in the matrix layer. , it is possible to obtain primary color signal outputs that compensate for signal level fluctuations due to temperature.

[Brief explanation of the drawing]

Fig. 1 is an RGB matrix circuit diagram of an embodiment of the present invention, Fig. 2 is a circuit diagram for explaining the RGB matrix and halftone processing, and Fig. 3 is a circuit diagram for explaining the R, G B matrix and temperature compensation. 4 is a block diagram of the video output part, and FIG. 5 is a block diagram of the RGB interface circuit 4 and R
FIG. 2 is a block diagram of a video output portion using the GB matrix circuit 5. FIG. Patent applicant: Fujitsu General Ltd. Figure 1 Figure 4 Figure 5

Claims (2)

[Claims] (1) In an RGB matrix circuit that inputs a color difference signal and a luminance signal to generate a primary color signal, the first transistor for the matrix, which applies the color difference signal and the luminance signal to the base and emitter, respectively, is a monochromatic part. None, a second transistor connected to the output of the first transistor via a diode and a gain control resistor; An RGB matrix circuit characterized in that the transistor is switched, and the gain control resistor is connected in parallel to the load resistor of the first transistor. (2) a third transistor whose base is connected to the output of the first transistor and whose emitter resistance and collector resistance are substantially the same; and a fourth transistor whose base is connected to the output of the third transistor; 2. The RGB matrix circuit according to claim 1, wherein the one-color portion is constituted by a primary color signal output transistor.