JPH036592A - Color selecting circuit of display device - Google Patents

Abstract

PURPOSE:To display characters without reference to whether the background is black or white by connecting individual selecting circuits of three systems for the respective colors of a digital RGB signal and a simultaneous normal/ inverted state selecting circuit for the three systems in front of the three systems. CONSTITUTION:The circuit 3 which inverts all the colors of the digital RGB signal independently is provided in front of a color selecting circuit. Then when the background color is white, a background color selection terminal 8 is set at an H level, so the signal is inverted to transmit a red signal R and an AND gate 4 transmits the red signal R in its normal state only when a color selection terminal 9 is at the H level. The red signal R is put together by an OR gate 5 with a green signal G and a blue signal B which pass through similar circuits and their composite RGB signal 7 is inputted through an EXOR gate 6 which is controlled through a black-and-white inversion terminal 10. Consequently, whichever the background is white or black, the RGB composite signal which can display an image is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color selection circuit for a two-tone black-and-white matrix display device such as a liquid crystal display externally connected to a computer having a digital color display function.

C. Summary of the Invention The present invention provides a color selection circuit for a two-tone black-and-white matrix display device, which is capable of displaying a screen in both a black background display mode and a white background display mode of a computer. It is an object.

[Conventional technology]

The conventional color selection circuit, as shown in FIG.
Each color of GB signal (red green blue signal) (red signal R1 green signal G,
After receiving the blue signal B) through the pull amplifier resistor 1 and buffer 2, an AND gate 4 for color selection is provided, and the AND gate 4 is provided for color selection.
The circuit configuration was such that the respective outputs of the digital RGB signals of the gates were combined by an OR gate 5 and sent as a black and white binary RGB composite signal to the display controller of the matrix display device.

[Problem to be solved by the invention]

However, in this method, when digital RGB signals are converted to two-tone black and white data, all colors other than black "0" are treated as the same white "l", so data such as color character display on a white background is There was a drawback that everything became white "1" and no display could be made.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a circuit for inverting all the digital RGB signals for each color independently in the case of a white background, in the preceding stage of the conventional color selection circuit. It is now possible to use a two-tone black-and-white matrix display device.

〔Example〕

The present invention will be explained below based on FIG.

FIG. 1 is a circuit diagram of a color selection circuit of the present invention.

The color selection circuit consists of a pull amplifier resistor l, a pumper 2, and an EX
Digital RGB consisting of OR gate 3 and AND gate 4
It consists of three systems of circuits corresponding to each color of the signal, and an OR gate 5 and an EXOR gate 6 that combine the signals of these three systems.

Next, the operation of the color selection circuit will be explained using FIG. Since each color of the digital RGB signal passes through a similar circuit, the red signal R will be explained. The red signal R is input to one side of the EXOR gate 3 after passing through an input interface circuit consisting of a pull amplifier resistor l and a buffer 2.

The signal from the background color selection terminal 8 is input to the other side of the EXOR gate 3, and when the background color is black, the background color selection terminal 8 is set to L level, so the EXOR gate 3 rotates normally. The red signal R is transmitted as it is. However, when the background color is white, the background color selection terminal 8 is set to H level, so the red signal R is inverted and transmitted. The red signal R is then input to one of the AND gates 4. AN
A signal from the color selection terminal 9 is input to the other side of the D gate 4, and the AND gate 4 selects a 0 color that transmits the red signal R with normal rotation only when the color selection terminal 9 is at i (level). Terminal 9 independently selects each color of the digital RGB signal.
Can be set to non-select. Next, the red signal R is OR gate 5 with the green signal G and blue signal B' which have passed through a similar circuit.
EXO is controlled by the black and white inversion terminal 10 after being synthesized by
The signal is input as an RGB composite signal 7 via an R gate 6 to an input terminal of a controller IC of a matrix display device.

When the digital RGB signal passes through the above circuit, the colors that can be identified are blue, red, purple, green, light blue, yellow, and white in black background mode.For example, the characters on the character display are displayed as white. Is displayed. However, if the background is a color other than the blackboard,
Since the background is white and the display is two-tone black and white, the characters cannot be identified.

On the other hand, in white background mode, the distinguishable color is blue.

The colors are red, purple, green, light blue, yellow, and black; for example, characters are displayed as black. However, if the background is a color other than white, the background will be black and the characters will not be distinguishable.

Furthermore, if a white background and a black background exist at the same time, one of them will be displayed in solid black or solid white and cannot be displayed.

In the embodiments described above, by providing a black background display function, a white background display function, and a setting function for independently selecting/deselecting red, green, and blue, a two-tone monochrome display device can be used. Being able to display a relatively visible range on an 8-color computer screen, and digital R.
Since each of the GB signals passes through a similar circuit without feedback, the transmission delay time when passing through the circuit is equal, and synchronization between the three digital RGB signals is less likely to occur even when operating at high speed. There is.

〔Effect of the invention〕

As explained above, the present invention provides an RGB composite signal that can display an image on both a white background and a black background by providing a circuit that performs normal rotation/inversion of digital RGB signals at the front stage of a conventional color selection circuit. Because it can be created, it is possible to display the computer's 8-color display on a two-tone black-and-white matrix display device, although there is a limit, and because the circuit can operate at high speed, it has the effect of being applicable to high-definition matrix display devices. be.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a color selection circuit of a display device according to the present invention, and FIG. 2 is a circuit diagram of a color selection circuit of a conventional display device. 3.6...EXOR gate 4...AND gate 5...OR gate 7...RGB composite signal R...Red signal G...Green signal B・・・・・・green light

Claims (1)

[Claims] 2 connected to a digital RGB signal of a computer, etc.
In the video signal input circuit of the gradation black-and-white matrix display device, three systems of individual selection circuits for each color of the digital RGB signal and three systems of simultaneous normal/normal rotation/selection circuits are provided in front of each of the individual selection circuits.
A color selection circuit for a display device, characterized in that by connecting an inversion selection circuit and configuring the circuit, characters can be displayed on either a black background or a white background.