JPH0417487A - Picture display device - Google Patents

Abstract

PURPOSE:To make a superimposed picture clearly visible by using a blanking signal so as to border the vicinity of superimposed display information and controlling a level of a main picture at a display position of the display information with the display information itself so as to make the brightness of the master picture of the display position of the sub picture. CONSTITUTION:A half blanking circuit 11 receiving a blanking signal attenuates a signal level of three colors R, G, B of a main picture to a half. Then three color signals r, g, b of the sub picture outputted from terminals R, G, B are inputted to an OR circuit 22. An output signal from the OR circuit 22 is inputted to a level control circuit 12 to make the signal level of each of the three color signals of the main picture zero for a period corresponding to a pulse width of the pulse outputted from the OR circuit 22.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a display medium that displays color images with two types of images of different properties (for example, a television broadcast image and a character image for displaying a serial number or a time display). The present invention relates to an image display device used when simultaneously displaying character images (character images).

[Summary of the invention]

When displaying a sub-image such as text or graphics superimposed on a main image, the brightness of the main image in the vicinity of the superimposed sub-image is lowered and the sub-image is displayed in order to make the superimposed image appear clearer. An image display device characterized in that the brightness of a main image at a position is reduced to zero by adding a simple logic circuit to an existing screen display integrated circuit.

[Conventional technology]

A conventional color display medium (for example, a color cathode ray tube) has two types of images with different properties, such as a television broadcast image (hereinafter referred to as the main image) and a character image for displaying a channel number or a character image for displaying the time (hereinafter referred to as a sub-image). ) When displaying images simultaneously, a technique is known in which the brightness of the main image is lowered and superimposed.

Hereinafter, as a conventional example, Japanese Unexamined Patent Publication No. 63-234679 will be explained using FIG. 4. In the figure, a video signal processing circuit 1 generates three primary color signals R,
G and B are demodulated, and these three primary color signals R, G, and B are outputted from an output terminal 5.6.7 via a synthesizer 2.3.4.

In this display device, various adjustments are made using adjustment data generated from the microcomputer 8. That is, the microcomputer 8 outputs image quality adjustment data such as color tone, color density, brightness, sharpness, etc. This image adjustment data is supplied to the D/A conversion circuit 9. This image quality adjustment data is converted into an analog control voltage in the D/A conversion circuit 9, and this analog control voltage is supplied to the video signal processing circuit 1. The image quality is then adjusted using an analog control voltage.

Commands are given to the microcomputer 8 from a key switch (not shown) arranged on an operation panel (not shown). Based on this command, image quality adjustment is performed. Furthermore, various display signals are output from the display generation circuit 10 in response to commands from a key switch (not shown). This display signal is superimposed on the three primary color signals R, G, and B output from the video signal processing circuit 1 by a synthesizer 2.3.4, respectively. When it is desired to draw attention to the display, the brightness of the main image is lowered. On the other hand, the brightness of the displayed characters remains unchanged.

In addition to the technology in the publication described as the conventional example, there is a known technology in which when a sub-image is superimposed on a main image, the brightness of the main image at the display position of the characters/figures in the sub-image is set to zero, that is, the characters/figures are displayed. There is a method of erasing (blanking, or reducing the brightness to zero) the signal of the main image at the display position of the figure and superimposing the sub-image.

[Problem to be solved by the invention]

However, in such conventional image display devices, since the colors of the main image and the sub-image are mixed, there is a problem that the color of the characters and figures in the sub-image changes depending on the color of the main image.

Also, blanking the sub-image display position of the main image to make the sub-image heavier is because, for example, if the color of the sub-image is red and the color of the main image is the same red, the characters and figures in the sub-image may be difficult to see. (There is a problem with that.

The present invention was made in response to such problems, and when superimposing a sub-image on a main image, it uses an existing central processing unit (CPU) for screen display to superimpose the characters and graphics of the sub-image. It is an object of the present invention to provide an image display device that is easy to see by lowering the brightness of the main image near the display position and further reducing the brightness of the main image at the display position of characters and figures to zero.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a sub-image signal generation circuit that outputs a sub-image signal, and a sub-image display position of a main image and a brightness level in the vicinity thereof. A blanking signal generation circuit, an OR circuit that takes the logical sum of three color signals of red, green, and blue of the sub-image, a level control circuit that controls the signal level of the main image by the output signal of this OR circuit, and a main It consists of a synthesis circuit that synthesizes signals of the same color of the three colors of the image and the sub-image.

[Operation] Since the display information of the sub-image superimposed on the main image is characters and figures, the waveform of the signal is generally a rectangular wave.

This rectangular wave signal is used to control the brightness of the main image to zero, and is also used as a signal to be superimposed on the main image.

(Example〕 Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a circuit showing one embodiment of the present invention. In the figure, three color signals of R, G, and B of the main image signal are constantly input to the half blanking circuit 11 with temporal changes. The three color signals of the main image whose levels have been controlled in the half blanking circuit 11 are input to the level control circuit 12 . The three color signals of the main image, whose levels have been further controlled in the level control circuit 12, are sent to a synthesizer 13.
14.15, is combined with the three color signals r, g, and b of the sub-image, and is output to terminals 16, 17, and 18. On the other hand, the tube display CPU 19 has a built-in sub-image ROM 21, and inputs signals of three colors r, g, and b of the sub-image to terminals (R), (G), and (B) by external operation. Output from

In addition, the screen display CPU 19 sends a blanking signal (BCK
) output from the terminal. The half-blanking circuit 11 that receives the blanking signal attenuates the levels of the three color signals of R, G, and B of the main image by half. This effect is
Continues while the blanking signal is input. Next, (R
), (G), and (B), the three color signals of the sub-images r, g, and b are input to the OR circuit 22.

The OR circuit 22 is an OR circuit that outputs "1" when any one of the three color signals r, g, and b is input, and its pulse width is determined by the input r, g, and b. The output signal from the OR circuit 22 is input to the level control circuit 12, and the signal level of each of the three main image color signals is set to zero for a period corresponding to the output pulse width from the OR circuit 22. The half-blanked and level-controlled main image R2, G2, and B2 color signals are sent to the synthesizer 13.
．． At 14.15, signals of the three colors r, g, and b of the sub-image outputted from the sub-image ROM 21 are added and combined with the same color signals to become R2+r, G2+g, and Bz+b, which are sent to the terminal 16.
It will be output on 17.18.

FIG. 2 is an explanatory diagram of a display state of the present invention, and FIG. 3 is an explanatory diagram of a signal waveform of the present invention.

FIG. 2 shows a display state when the main image is, for example, an image with constant brightness, and a sub-image called "lch" is superimposed on the main image.

Figure 3 explains the waveform of the signal at location A-A in Figure 2, where (a) is half blanking of the main image, the waveform of R+G+B before blanking processing, and (b) is the waveform of the sub image. (C) is the waveform of r+g+b after half blanking and level control.
B2+b) waveform. Half blanking circuit 11
As a result, the signal level of the main image is reduced from d to half, d/2, and is framed.

〔Effect of the invention〕

As explained above, according to the present invention, the existing snow surface display CPU outputs only one blanking signal.
The border around the superimposed display information is created using a blanking signal, and the level of the main image at the display position of the display information is controlled by an external circuit using the display information itself, making it possible to produce clear superimposed images. Obtainable.

Furthermore, since a simple OR circuit is used as an external circuit, its economical effect is also great.

[Brief explanation of drawings]

FIG. 1 shows a block diagram of the circuit of the present invention, FIG. 2 shows an explanatory diagram of the display state of the present invention, FIG. 3 shows an explanatory diagram of the signal waveform of the present invention, and FIG. 1 shows a block diagram of a conventional circuit. 11---------Half blanking circuit 12---------One level control circuit 13, I4.15---Synthesizer 19 ------・-11----------------------CPU 2l for screen display----------1 Sub-image ROM 22---- −−−−−・−−−−−−O
R＠Route Fig. 2 Display of main investigation () (explanatory diagram of state)

Claims (1)

[Claims] Red, green, and blue 3 that make up the display information of the main image
An image display device that combines and displays three color signals of red, green, and blue constituting display information of a sub-image in each color signal, and outputs the three-color signals of the sub-image. A sub-image signal generation circuit, a blanking signal generation circuit that generates a blanking signal, an OR circuit that takes the logical sum of the three color signals of the sub-image, and an output signal of the blanking signal generation circuit to generate the sub-image. a half-blanking circuit that controls the display position of the display information of the sub-image and the signal level of the main image in the vicinity thereof; and a half-blanking circuit that controls the signal level of the main image at the display position of the display information of the sub-image by the output signal of the OR circuit. 1. An image display device comprising: a level control circuit for composing signals of the three colors of the main image and the sub-image;