JPH0428152Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a TTL signal processing circuit used in a video circuit of a display.

BACKGROUND TECHNOLOGY In recent years, computers have been widely used in industry and households, and the display colors of computer-controlled cathode ray tubes (hereinafter referred to as CRTs) have changed from the original eight colors to multicolor displays. is increasing. Displays connected to computers are also being forced to support multicolor display, or in order to be able to connect to various computers, for example, 8
There are requests for something that can connect both colors and 16 colors.

Below, while referring to the drawings, we will introduce the conventional 16-color compatible
The TTL signal processing circuit will be explained.

FIG. 2 shows the configuration of a conventional TTL signal processing circuit that supports 16 colors. In Figure 2, 1 and 2 are NAND gate circuits that perform waveform shaping and inversion of the computer's TTL luminance signal; 3, 4, and 5;
is waveform shaped and inverted NAND gate circuit 1
NAND gate circuits that process the output signals of and 2 in 16 colors; 6 and 7 are resistors that always keep one of NAND gate circuits 1, 3, and 5 at H level and also serve as current protection; 8 and 9 are resistors of the computer. This is a resistor that determines the mixing ratio of the two TTL luminance signals.

The operation of the conventional TTL signal processing circuit configured as described above will be explained below.

First, the brightness signal (INT) of the computer is
The waveform is shaped and inverted by the NAND gate circuit 1. Next stage NAND gate circuit 3,
4 and a resistor 8 which determines the mixing ratio of the TTL luminance signal, a luminance signal level of 2/3 of the normal MAX luminance is output.

The brightness signal of the other computer is NAND
The waveform is shaped and inverted by the gate circuit 2. And the next stage NAND gate circuit 4,
5 and a resistor 9 which determines the mixing ratio of the TTL luminance signal, a luminance signal level of 1/3 of the normal MAX luminance is output.

When both brightness signals from the computer are input, a brightness signal level of MAX brightness is outputted by the NAND gate circuits 3, 4, 5 and the resistors 8, 9 that determine the mixing ratio of the TTL brightness signal.

Problems that the invention aims to solve However, with the conventional structure as described above,
In the case of an eight-color computer, the problem is that the brightness is reduced because the brightness signal is not input to one side.

The present invention was developed in view of the above-mentioned conventional problems, and provides a TTL signal processing circuit that can output images without reducing screen brightness, regardless of whether it is connected to an 8-color or 16-color computer, for example. It is.

Means for Solving the Problem To achieve this objective, the TTL signal processing circuit of the present invention includes a gate circuit that constitutes a circuit that processes signals of a plurality of predetermined colors, and a display screen of a display to be connected to a computer. and switching means for switching the color mode according to the types of colors that can be displayed, and the switching means controls the gate circuit so that the brightness of the display screen is kept constant regardless of the types of colors that can be displayed. It is composed of

Function: With this configuration, there is no reduction in brightness when an 8-color computer is connected, so it can be connected to both 8-color and 16-color computers.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a signal processing section of a TTL signal processing circuit in an embodiment of the present invention.

In FIG. 1, 10 is a switch for switching between 8-color and 16-color computers, 11 is a NAND gate circuit for switching to set the output level to the next stage to H level or L level, and 12 is a switch for switching between 8 colors and 16 colors. This resistor sets the input of the switching NAND gate circuit 11 to H level and also serves as current protection.

In addition, NAND gate circuits 1 to 5 and resistors 6 to 9 are as follows:
This is the same configuration as the conventional example shown in FIG. Furthermore, the three blocks surrounded by dotted lines have the same configuration.

The operation of the TTL signal processing circuit configured as described above will be explained below.

First, when connecting to an 8-color computer,
By setting the 16-color selector switch 10 to the 8-color side, the output of the NAND gate circuit 11 becomes L level. Next, NAND gate circuit 3 of NAND gate circuits 3, 4, and 5 that constitutes the 16 color processing circuit
and 5 are turned off because the output of the NAND gate circuit 11 is at L level. Then, since only the NAND gate 4 is turned on, a luminance signal level of MAX luminance is output.

Next, when connecting to a 16-color computer, use 8
By setting the 16-color selector switch to the 16-color side
The output of the NAND gate circuit 11 becomes H level.
And NAND gate circuit 3, which constitutes a 16-color circuit,
4 and 5 are all turned on (ON), so when both luminance signals are input, the luminance signal level of MAX luminance is output.

As described above, according to this embodiment, by configuring the 8-color and 16-color changeover switches and the NAND gate circuit, it can be used for both 8-color and 16-color computers.

In this embodiment, 8 colors and 16 colors are changed using the changeover switch 10, but if there is a discrimination signal from the computer, the changeover switch becomes unnecessary. Furthermore, although only computers for 8 colors and 16 colors have been described, the present invention is also applicable to computers that support even more colors, such as computers for 16 colors and 64 colors.

Effects of the invention As described above, the present invention is able to maintain a constant brightness without reducing the brightness of the screen, regardless of whether it is connected to an 8-color computer or a 16-color computer. .

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a TTL signal processing circuit according to an embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional TTL signal processing circuit. 1 to 5...NAND gate circuit, 11...NAND gate circuit for switching, 6 to 9, 12...Resistance,
10... Changeover switch.

Claims (1)

[Scope of utility model registration request] It has a gate circuit that constitutes a circuit that processes signals of a plurality of predetermined colors, and a switching means that switches the color mode according to the types of colors that can be displayed on a display screen of a display connected to a computer, and the switching means A TTL signal processing circuit configured to control the gate circuit so that the brightness of the display screen is kept constant regardless of the types of colors that can be displayed.