JPH0238313Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a cathode ray tube color display device, and in particular, it is capable of displaying eight colors (black, red,
This invention relates to a cathode ray tube color display device that displays images in a total of 16 colors on a cathode ray tube by changing the brightness of green, blue, magenta, cyan, yellow, and white into two levels.

BACKGROUND ART The colors that can be displayed in a cathode ray tube color display device are usually black, red, green, blue, magenta, cyan,
In addition to the eight colors of yellow and white, in order to display intermediate colors other than these, conventionally, an intensity signal that controls brightness is added to the three primary color signals of red, green, and blue.
The amplitude of the three primary color signals of red, green, and blue is left as is when the intensity signal is “high” and is set to “low”.
In this case, there is a color display device that reduces the brightness using a resistor or the like and adds two gradations to the brightness so that a total of 16 colors, including the above eight bright colors and dark colors, are displayed. Figure 1 shows the red signal S _R and green signal in this case.
FIG. 3 is a diagram showing the correspondence between signal levels of S _G , blue signal S _B and intensity signal S _INT and colors displayed on a cathode ray tube. As you can see from this diagram, for colors other than black, there is a red signal S _R , a green signal S _G , and a blue signal
At least one of S _B is the white level, and in the case of black, these color signals S _R , S _G , and S _B are all the black level, and the “high” and “low” intensity signals
Regardless, black is just black, and there is no such thing as "bright black" or "dark black." That is, in this conventional device, black is displayed twice, and the number of colors actually displayed is 15.

DISCLOSURE OF THE INVENTION The present invention was proposed in view of the above-mentioned problems, and uses three primary color signals of red, green, and blue and an intensity signal that controls brightness to produce black, red, green, blue, magenta, cyan, and yellow. In a cathode ray tube color display device, in which the brightness of each of the eight colors of white is changed to two levels to display a total of 16 color images on a cathode ray tube, when the intensity signal is at one of the values, black is displayed. An object of the present invention is to provide an intermediate color signal generation circuit that converts a three primary color signal for displaying a color to a three primary color signal for displaying an intermediate color other than the above-mentioned eight colors.

To this end, the present invention inputs three primary color signals and an intensity signal, and when all three primary color signals are black level and the intensity signal, which takes a binary value, is one of the values, one of the three primary color signals is input. a signal processing circuit that converts at least one to a white level and outputs a control signal; and one or more of the three primary color signals output from the signal processing circuit when the control signal is output, and the white level and black level, respectively. and a level adjustment circuit that adjusts the level to a predetermined intermediate level between the two.

Therefore, according to the present invention, black can be displayed once instead of twice, and any neutral color, which was previously impossible, can be displayed with a simple circuit configuration.

Best Mode for Carrying Out the Invention Figure 2 shows an embodiment of the invention, in which 3
FIG. 2 is a circuit diagram of an intermediate color signal generation circuit that converts a primary color signal into three primary color signals that display gray. T _Ri , T _Gi ,
T _Bi and T _iNT are respectively red signal S _R , green signal S _G ,
This is a terminal to which the blue signal S _B and intensity signal S _INT are input. 1 and 6 are inverter circuits, 2 is a NOR circuit, and 3, 4, and 5 are exclusive OR circuits, which constitute the aforementioned signal processing circuit.
7, 8, and 9 are inverter circuits, and R ₁ , R ₂ , and R ₃ are resistors (in this case, R ₁ =R ₂ =R ₃ ), which constitute the level adjustment circuit. T _RO , T _GO , and T _BO are output terminals for the red signal _SR , green signal _SG , and blue signal _SB to the amplifier circuit, respectively.

Next, the circuit operation will be explained. Terminals T _Ri , T _Gi , T _Bi
A red signal S _R , a green signal S _G , and a blue signal S _B that are all “low” (= black level) are input from the terminals.
If a “high” intensity signal S _INT is input from T _INT , the output of NOR circuit 2 will be “low”, so exclusive OR circuits 3, 4, 5
All outputs are “high”. On the other hand, since the output of the inverter circuit 6 becomes "high", the outputs of the inverter circuits 7, 8, and 9 all become "low". Therefore, exclusive OR circuits 3, 4, 5
The voltage at the output terminal of is dropped by the resistors R ₁ , R ₂ , and R ₃ , respectively, and becomes an intermediate level, and the voltage at the terminal T _RO ,
From T _GO and T _BO , this intermediate level red signal S _R ,
A green signal S _G and a blue signal S _B are output. That is, color signals S _R , S _G , and S _B that display black are converted to color signals S _R , S _G , and S _B that display gray. red traffic light
S _R , green signal S _G , blue signal S _B and intensity signal S _INT Except for the above cases, the output of OR circuit 2 is “high”, so the input red signal S _R , green signal S _G , blue signal The signal S _B passes through the exclusive OR circuits 3, 4, and 5 as they are, and is connected to the resistor.
The level is not adjusted by R ₁ , R ₂ , R ₃ and the terminal
Output from T _RO , T _GO , T _BO , black, red, green, blue,
The colors magenta, cyan, yellow, and white appear on the screen.

By changing the values of resistors R ₁ , R ₂ , and R ₃ , it is possible to create color signals of other neutral colors than gray.
In the example, when converting to an intermediate color signal,
All of the color signals S _R , S _G , and S _B input to the exclusive OR circuits 3, 4, and 5 are inverted, but only some of them may be inverted.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the signal levels of each color signal displayed on a cathode ray tube and the intensity signal when 16 colors are displayed using intensity signals, and Figure 2 is an example of the present invention. Display black 3
FIG. 2 is a circuit diagram of an intermediate color signal generation circuit that converts a primary color signal into three primary color signals that display gray. 1...Inverter circuit, 2...NOR circuit, 3,
4, 5... exclusive OR circuit, 6, 7,
8, 9...Inverter circuit, _R1 , _R2 , _R3 ...Resistance.

Claims (1)

[Claims for Utility Model Registration] The luminance of each of the eight colors black, red, green, blue, magenta, cyan, yellow, and white is controlled by the three primary color signals of red, green, and blue and the intensity signal that controls the luminance. In a cathode ray tube color display device that displays a total of 16 colors of images on a cathode ray tube in two stages, the three primary color signals and the intensity signal are input, and the three primary color signals are all at black level. hand,
a signal processing circuit that converts at least one of the three primary color signals to a white level and outputs a control signal when the binary intensity signal has one of the values; and a signal processing circuit that outputs the control signal. A level adjustment circuit is provided for adjusting the level of one or more of the three primary color signals outputted from the signal processing circuit to a predetermined intermediate level between the white level and the black level, and the three primary color signals for displaying black are provided. An intermediate color signal generation circuit characterized in that the primary color signal is converted into three primary color signals for displaying intermediate colors other than the eight colors.