JPH0314711Y2 - - Google Patents

Description

[Detailed explanation of the idea]

Industrial Application Field The present invention switches and outputs three primary color signals for a graphic screen and three primary color signals for a text screen to an image display device that displays a graphic screen and a text screen in a superimposed manner, for example. The present invention relates to a color signal output device for color images. BACKGROUND ART FIG. 2 is a diagram showing the configuration of a color signal output device for color images in the prior art. When displaying color images on the graphics screen or text screen of a typical personal computer, each of the three primary colors red, blue, and green is treated as 1 bit each, and treated as a total of 3 bits of information. Color images are displayed in eight colors: cyan, green, yellow, white, and black. For example, in the case of black, the red, blue, and green bits are each 0.
It is stipulated that In this embodiment, when a text screen is displayed superimposed on a graphics screen, the portion of the text screen where a character, which is a character, symbol, or figure, exists is given priority in displaying that character. is displayed. Configuring the graphics screen 3
The color signals of blue B, red R, and green G, which are primary colors, are input from the color signal generating means GR to terminals B1 to B3 of a color signal selection circuit DS called a data selector, respectively. The color signals of blue B, red R, and green G, which constitute the three primary colors constituting the text screen, are sent from the color signal generating means TX to each terminal A1 of the color signal selection circuit DS.
It is input to A3 and also given to NOR gate GA. The output signal of this NOR circuit GA provides a low level signal to the terminal S of the color signal selection circuit DS when the text screen color signals B, R, and G are input. When a low level signal is input to the terminal S of the color signal selection circuit GS, the color signal selection circuit DS selects the text screen color signals B, R, and G, and outputs the text screen color from the output terminals Y1 to Y3. Signal B,
Output R and G to a color image display device CRT.
Text screen color signals B, R, to NOR gate GA
When G is not input, a high-level signal is derived from the NOR circuit GA to the terminal S of the color signal selection circuit DS, and the color signal selection circuit DS sends the color signals B, R, and G for the graphic screen to the color image display device CRT. Output. Problems to be Solved by the Invention In the prior art color signal selection circuit as shown in FIG. 2, it is not possible to superimpose the characters of a text screen on a graphics screen and display them in black. When the text screen character is black, the text screen color signals B, R, and G are all low level, the output of the NOR circuit GA is high level, and the color signal selection circuit DS selects the graphic color signals B, R, and G. Since R and G are selected and output, the black character is not displayed. SUMMARY OF THE INVENTION An object of the present invention is to provide a color signal output device for a color image that can easily superimpose characters on a text screen on a graphic screen and display them in black. Means for Solving the Problems The present invention provides a color signal generating means TX that generates a signal representing the color in which characters on a text screen should be displayed.
, a graphics random access memory GR for storing image data to be displayed on the graphics screen, attribute data AD4 for selecting black display for each character, and attribute data AD1 representing the color to be displayed in black. -AD3, and when black display is selected in response to the signal from the color signal generation means TX and the stored contents of the attribute random access memory 9, the color signal is generated. Comparing means 2 for comparing the color represented by the signal generated from the means TX and the color to be displayed as black, and generating a matching signal when these colors match;
and in response to the signals from the color signal generating means TX and the comparing means 2, when the matching signal is derived, a signal representing black is derived, and when the matching signal is not derived, the signal representing black is derived from the color signal generating means TX. In response to the signals from the first gate circuits 4 to 7 for deriving signals, the color signal generating means TX and the comparing means 2, a signal representing black is derived from the color signal generating means TX, and a signal representing black is derived from the comparing means 2 and 9. a second gate circuit 3 that derives a signal indicating that the coincidence signal is not derived only when the signal is not derived; the contents stored in the graphic random access memory GR; the first and second gate circuits 4 to 7;
In response to the signal from the second gate circuit 3, when the signal indicating that the coincidence signal is not derived from the second gate circuit 3, the signal from the first gate circuits 4 to 7 is derived from the second gate circuit 3, and the signal from the second gate circuit 3 is derived from the second gate circuit 3. When a signal indicating that a coincidence signal is not derived is derived, the graphics screen includes a color signal selection circuit 1 which derives the stored contents of the graphics random access memory GR; This is a color image display device characterized by displaying a color image in which a text screen is superimposed on a screen. Operation According to the present invention, a signal representing the color in which a character on a text screen is to be displayed is generated by the color signal generating means TX. The color represented by this signal is compared with a predetermined color in comparison means 2 and 9.
When the colors match, the first and second gate circuits 4 to 4 respond to matching signals from the comparing means 2 and 9.
7 and 3 can derive a signal for displaying a character in black from the color signal selection circuit 1. Embodiment FIG. 1 is a circuit diagram showing the configuration of a color signal output device according to an embodiment of the present invention. When displaying color images on the graphics or text screen of a typical personal computer, each of the three primary colors red, blue, and green is treated as 1 bit each, and treated as a total of 3 bits of information. Cyan, green, yellow, white, black 8
A color image is displayed using colors. For example, in the case of black, each of the red, blue, and green bits is 0; in the case of yellow, the red and green bits are 1; and the blue bit is 0; and in the case of white, each of the red, blue, and green bits is 0. Each bit is set to 1.
A color signal for a graphic screen and a color signal for a text screen, in which 8 colors are expressed in 3 bits, are input to a color signal selection circuit 1 called a data selector, and one of them is selected and output to the color image display device.
Although it is output to a CRT, in the conventional technology it was not possible to display the characters, which are characters, symbols, or figures on the text screen, in black over the graphic screen, but in the present invention, the following configuration is used. Characters on the text screen can be displayed in black by superimposing them on the graphic screen. Color signals B, R, and G for graphic screens are
According to the memory address MA and raster address RA output from the CRT (cathode ray tube) controller CRTC, which outputs information signals regarding the display screen, the color signal generation means GR outputs information signals to terminals B1, B2, and B3 of the color signal selection circuit, respectively. is input. On the other hand, a memory address MA is given from the CRT controller CRTC to the text RAM 8 in accordance with the display contents of the text screen, and is also given to the attribute RAM 9 in order to output a color signal corresponding to each display character. The text RAM 8 given the memory address M outputs a character code corresponding to the display character to the character generator 10. The character generator 10 supplies display data corresponding to the character code to the color signal generating means TX via the parallel/serial converter 11 in accordance with the tester address RA input from the CRT controller CRTC. Also at this time, attribute RAM9
The color information for each character is sent to the color signal generation means TX.
and provides attribute data, which will be described later, to the logic circuit RC. Text screen signals B, R, G
are applied from the color signal generating means TX to the comparison circuit 2, the NOR gate 3, which is a second gate circuit, and the AND gates 4, 5, and 6 included in the logic circuit RC, respectively. The comparator circuit 2 has its terminal B11,
The three primary color signals B, R, and G for the text screen are input to B12 and B13, and each character of the text screen is input from the attribute RAM 9.
An attribute data signal indicating an attribute individually corresponding to each is input as a control signal. The attribute data is expressed in 4 bits, and each of the data AD1 to AD4 has contents as shown in Table 1 below.

[Table] Attribute data signal AD1 is applied to terminal A11 of the comparison circuit, attribute data signal AD2 is input to terminal A12 of comparison circuit 2,
The attribute data signal AD3 is input to the terminal A13 of the comparison circuit 2. The attribute data signal AD4 is input to the input terminal IA, which controls the operating state of the comparator circuit 2. For example, when the attribute data signal AD4 is 0 and is at a low level, the comparison circuit 2 is not activated. When the attribute data signal AD4 is 1 and at a high level, the comparison circuit 2 is activated. Three primary color signals B, R, G and attribute data signal AD for text screen
1 to AD3 correspond to each other, and when the attribute data signal AD4 is at a high level, the output of the comparison circuit 2 changes from a low level to a high level. The output signal of this comparator circuit 2 is output from the output terminal
It is applied from OUT to one terminal of each AND gate 4, 5, 6 via NOR gate 3 and NOT circuit 7. That is, each AND gate 4, 5, 6
and NOT circuit 7 constitute a first gate circuit.
When the NOR gate 3 receives a high level signal from the comparison circuit 2, it inputs a low level signal to the terminal S of the color signal selection circuit 1. Color signal selection circuit 1
In this case, when the input signal applied to the terminal S is at a high level, the color signals B, R, and G for the graphic screen are outputted from the output terminals Y1 to Y3 to the color image display device.
Output the color signals B, R, and G to the CRT and terminal S
When the input signal given to is low level, the text screen color signals B, R, G are output from terminals Y1 to Y
3 to the color image display device CRT.
AND gates 4, 5, and 6 open their gates when the output signal from comparison circuit 2 is at a low level, and each color signal B, R, and
G is applied to terminals A1 to A3 of the color signal selection circuit 1, respectively. Furthermore, the AND gates 4, 5, and 6 cut off their gates when the output from the comparator circuit 2 is at a high level, and apply low level signals to the terminals A1 to A3 of the color signal selection circuit 1, respectively. When the text screen characters are displayed in black overlaid on the graphics screen, the text screen color signals B, R, and G are each at a low level,
When the attribute data signals AD1 to AD3 are each at a low level and, for example, the attribute data signal AD4 is at a high level, a high level signal is derived from the comparator circuit 2. At this time, a low level signal is input from the NOR gate 3 to the terminal S of the color signal selection circuit 1, and the text screen color signals input to the input terminals A1 to A3 are selected. At this time, AND gates 4, 5,
6 has its gate cut off, and a low level signal is input to each terminal A1 to A3 of the color signal selection circuit 1. Therefore, the output terminal Y of the color signal selection circuit 1
The outputs of 1 to Y3 each become low level, and a color signal indicating black is output to the color image display device CRT. Effects As described above, according to the present invention, when the color in which a character on the text screen should be displayed matches the color stored in the attribute random access memory 9 as attribute data AD1 to AD3 for each character, the character is displayed. It can be displayed in black by superimposing it on the graphic screen. Attribute data AD indicates that such display should be displayed in black.
This can be easily done by simply selecting 4 and specifying the color for each character. Therefore, it is possible to display a color image by effectively using all displayable colors, including black. For example, in applied devices such as word processors, words that are currently being converted can be temporarily displayed in black to provide an easy-to-understand color image display. Further, according to the present invention, it is possible to select a color to be displayed as black from among the colors to be displayed as a character, and this selection does not affect the color displayed on the graphic screen. Therefore, only the character display can be changed to black without changing the background on the graphic screen. Furthermore, according to the present invention, when the color in which a character on a text screen should be displayed is black, by selecting black as the color to be displayed, the character can be displayed in black as it is; , the black part is treated as transparent and displayed on the graphic screen. Therefore, it is possible to switch between black, in which nothing is displayed, and transparent, in which the lower screen is displayed as is.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a color signal output device for color images according to an embodiment of the present invention, and FIG. 2 is a diagram showing the configuration of a color signal output device for color images in the prior art. 1... Color signal selection circuit, 2... Comparison circuit, 3...
...NOR gate, 4 to 6...AND gate, 7...
NOT circuit, B, R, G...color signal, AD1 to AD
4...Attribute data signal, RC...Logic circuit.

Claims (1)

[Scope of Utility Model Registration Claim] Color signal generating means TX for generating a signal representing the color in which characters on a text screen should be displayed, and a graphics random access memory GR for storing image data to be displayed on a graphics screen. , an attribute random access memory 9 for storing attribute data AD4 for selecting black display and attribute data AD1 to AD3 representing colors to be displayed in black for each character; and color signal generating means TX. When selecting black display in response to the signal from the color signal generator TX and the contents stored in the attribute random access memory 9, the color represented by the signal generated from the color signal generating means TX and the color to be displayed in black are selected. comparison means 2 for generating a match signal when these colors match;
and in response to the signals from the color signal generating means TX and the comparing means 2, when the matching signal is derived, a signal representing black is derived, and when the matching signal is not derived, the signal representing black is derived from the color signal generating means TX. In response to the signals from the first gate circuits 4 to 7 for deriving signals, the color signal generating means TX and the comparing means 2, a signal representing black is derived from the color signal generating means TX, and a signal representing black is derived from the comparing means 2 and 9. a second gate circuit 3 that derives a signal indicating that the coincidence signal is not derived only when the signal is not derived; the contents stored in the graphic random access memory GR; the first and second gate circuits 4 to 7;
In response to the signal from the second gate circuit 3, when the signal indicating that the coincidence signal is not derived from the second gate circuit 3, the signal from the first gate circuits 4 to 7 is derived from the second gate circuit 3, and the signal from the second gate circuit 3 is derived from the second gate circuit 3. When a signal indicating that a coincidence signal is not derived is derived, the graphics screen includes a color signal selection circuit 1 which derives the contents stored in the graphics random access memory GR; A color image display device characterized by displaying a color image in which a text screen is superimposed on a screen.