JPH0241673Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a color display device used as a display terminal for various information devices.

(b) Prior Art Color display devices such as those described in the introduction are capable of displaying a cursor superimposed on images such as characters and figures. The cursor color was changed only when the cursor color matched the underlying color.

FIG. 3 shows a conventional cursor display circuit using such a method. Reference numerals 1, 2, and 3 are input sections for receiving three primary color data Ri, Gi, and Bi representing characters or figures from a personal computer, etc.; Each input section is provided with four data lines corresponding to the above-mentioned data Ri, Gi, and Bi of 4-bit parallel (4 digits) (corresponding to 4096 colors). 4, 5, and 6 each have the respective data R, G, and B as one input, and the color data Rc, Gc, and Bc from the first and second cursor color setting circuits 7 or 8 as the other inputs.
A third multiplexer is provided, and each multiplexer is switched by a cursor pattern signal applied to line 9. And the first ~
Each output of the third multiplexer is
The signals are converted into analog signals by 3D/A conversion circuits 10, 11, and 12, and then applied to a color picture tube 13.

On the other hand, 14 is the input three primary color data R, G, B.
It is an AND gate that inputs only the most significant digit MSB directly and inputs the inverted output of the other digits, and the inverted output of this AND gate is
As a selection signal for the second cursor color setting circuits 7 and 8, it is applied directly to one of them 7, and inverted by an inverter 15 and applied to the other 8. Here, the color setting circuits 7 and 8 are both composed of switch circuits, etc., and the output of the color setting circuits 7 and 8 is composed of four of each of the three primary colors.
The digits, all 16 digits in total, represent "1" (+5V), which represents white, and the output of the other 8 shows that only the most significant digit of each of the above four digits is "1" and all other digits are "0".
(0V) (see Figure 4 A).

Therefore, according to this conventional circuit, the input three primary color data R, G, B are the aforementioned set colors (Fig. 4A).
The output of the AND gate 14 becomes "1" only when the value matches , and the first color setting circuit 7 operates (conducts).
Therefore, the first to third multiplexers 4, 5, 6
The data Ro, Go, and Bo output from the cursor pattern are white only during the period of the cursor pattern.
The cursor will be displayed in white on the color image No. 3. In addition, the input three primary color data Ri, Gi,
When Bi is any other color, the output of the AND gate 14 is always "0" and the second color setting circuit 8 is activated, so in this case the cursor is displayed in gray.

A cursor display circuit using a method similar to this conventional example is described in Japanese Patent Laid-Open No. 58-4195.

(c) Problems to be solved by the invention By the way, in the above-mentioned conventional circuit, even when the input three primary color data, that is, the background color becomes, for example, as shown in Figure 4 B, the cursor is displayed as gray corresponding to Figure 4 A. However, since the base color is a slightly lighter gray than the cursor color, there is a problem in that the cursor is very difficult to distinguish in this case. In addition, a color setting circuit is required for each of the two types of cursor colors, and a multiplexer with multiple digit inputs and an AND gate with multiple inputs are also required, which has the disadvantage of increasing the number of parts and increasing costs. It was hot too.

Therefore, the object of the present invention is to realize, with a very simple hardware configuration, a cursor display circuit that can clearly identify and display a cursor no matter what color the background of a figure or the like is.

(d) Means to solve the problem In this invention, two or more digits representing characters, figures, etc.
The sign of the upper digit of the input three primary color data in the base code format is inverted only during the period of the cursor pattern signal, and this three primary color data is derived as a display output.

(E) Effect According to the above configuration, the data representing the cursor is obtained by inverting the upper digits of the input three primary color data, so the color of this cursor differs greatly in tone and contrast from the underlying image. It can be clearly identified and displayed.

(F) Example Figure 1 shows an example of the present invention.
Although the same parts as those in the conventional circuit shown in the figures are given the same figure numbers and their explanations are omitted, this embodiment is characterized by the following configuration. That is, it is each 4-digit input data
A multiplexer 1 in which each of the most significant digits (MSB) of Ri, Gi, and Bi is input to one side, and each inverted output from the inverters 16, 17, and 18 is input to the other side.
9, and by switching this multiplexer in accordance with the cursor pattern signal applied to line 9, the sign of each of the most significant digits is inverted only during the period of the pattern signal, and then the sign of each of the most significant digits is inverted along with the other digits. /A conversion circuits 10, 11, and 12 are sent.

Therefore, according to this embodiment, the three primary color data Ri, Gi,
When Bi is input, the color of the cursor displayed on this color image becomes gray with a very slight yellow tinge, as shown in the figure. And the input data
Similarly, when Ri, Gi, and Bi indicate red and green, the cursor color will be approximately gray, and when the above input data indicates other intermediate colors, it will also be displayed in a tone close to gray. Become. Furthermore, when the above input data is gray as shown in Figure 4A, the cursor color is black with all 16 digits being "0", and when it is gray as shown in Figure 4B, the cursor color is black as shown in Figure 4B. Since all 16 digits are "1" (white), the cursor can be clearly identified in any of these cases.

In the above embodiment, the input three primary color data R,
Although only the most significant digits of G and B are inverted, for example, it is also possible to invert both the most significant digit and the next digit.In other words, if the contrast and color tone change significantly before and after inversion. Therefore, it is sufficient to invert the upper digits of the data R, G, and B.

(g) Effects of the invention According to the cursor display circuit of the invention, no matter what color the background of a figure, etc. Furthermore, unless the underlying color changes drastically, the cursor color is displayed in approximately the same tone, mainly gray, making it very easy to see.

Furthermore, there is no need for a color setting circuit for presetting the cursor color or a multiplexer for inputting multiple digits, and therefore there is an advantage that the number of parts is small, the hardware configuration is simple, and it can be realized at low cost. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a cursor display circuit according to the present invention, and FIG. 2 is a diagram for explaining its operation. FIG. 3 shows an example of a conventional cursor display circuit, and FIG. 4 is a diagram for explaining its drawbacks. 10, 11, 12: D/A conversion circuit, 13: Color picture tube, 9: Cursor pattern signal input line, 19: Multiplexer, Ri, Gi, Bi: Input three primary color data.

Claims (1)

[Scope of utility model registration request] In a color display device that obtains three primary color data each in the form of a multi-digit binary code and displays an image such as a character or a figure, the three primary color data are displayed only during a period of a pattern signal representing a cursor displayed on the image. A cursor display circuit for a color display device in which the sign of each upper digit is inverted and three primary color data after the inversion process are derived as a display output.