JPH05260508A - Digital display device - Google Patents

Abstract

PURPOSE:To reduce the cost of various electronic apparatuses by realizing at a low cost a function of a half tone display roughly equal to an analog display IC of a high performance and a high cost, in the digital display device provided with the display IC and a control microcomputer for the display IC. CONSTITUTION:In a display control CPU 8, a half tone control port I is provided, and also, in a digital output terminal of a display IC 10, an attenuator 11 is provided, and in the case the half tone control port I becomes ON (L level), a digital output signal outputted from the display IC 10 and attenuated by the attenuator 11 is decreased to about half by a resistor R1, and outputted as data of a half tone display.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital display device, and more particularly to a digital display device having a message display function such as character / graphic information.

[0002]

2. Description of the Related Art With the increase in various functions of current television receivers, there are increasing opportunities to output various information and messages on a screen. By the way, in the case of an ordinary television receiver, it is possible to display at most 8 colors by combining simple RGB display colors.
Further, it is preferable to increase the display color by using the intermediate color of RGB by using the analog display IC having the halftone function and to display the message in the program being viewed so as not to obstruct the image.

[0003]

However, although the analog display IC having the halftone function can express fine colors, it is necessary to finely control the output level by using an analog circuit. It was very expensive, and from an economical point of view, it could not be used for all products.

[0004]

The digital display device of the present invention has been made in order to solve such a problem. A halftone control port and an attenuator are provided, and the halftone control port is used for display. The digital output of the attenuator is substantially halved by the control of the IC control microcomputer.

[0005]

The halftone control port halves the digital output signal of the attenuator so that even a display IC without a halftone function can display half-tone display of character / graphic information and increase the display color. it can.

[0006]

EXAMPLES Examples of the case where the digital display device of the present invention is used in a television receiver will be described below.
FIG. 1 is a block diagram of a television receiver of this embodiment, particularly a video circuit system. In the figure, 1 is a U / V tuner for selecting terrestrial broadcasting, 2 is an intermediate frequency amplifier, 3 is various processing such as separation of color signals, formation of color difference signals, extraction of synchronization signals, and the like. (CRT)
A video signal processing unit to be supplied to 5 and 6 are control microcomputers for controlling the above-mentioned functional circuits, etc.
Select a broadcast channel and turn up / down the volume. Also, as described later, the display of the broadcast channel,
Outputs command data for outputting various information.

A display control CPU 8 has a halftone control port I for reducing the brightness of the display color. 9 is a horizontal sync counter for counting horizontal sync signals, 10A is a character generator, 1
0B is a video RAM, 10C is a signal output circuit, I
The functional circuit inside the display IC 10 which has been converted to C is shown. Reference numeral 11 denotes an attenuator connected to the RGB signal output terminals of the display IC 10, which is configured so that the output voltage can be reduced by the resistors R ₁ and r.

Next, the processing when the television receiver of this embodiment performs halftone display will be described with reference to the flowchart of FIG. When the data to be displayed on the screen is output from the control microcomputer 6 (F10), first, the vertical synchronizing signal is detected (F11), and the horizontal synchronizing signal counter 9 is reset by this vertical synchronizing signal to output the horizontal synchronizing pulse. Counting is started (F12), and when a predetermined count value, that is, a horizontal position at which data should be output is reached (F13), it is determined whether or not the data is displayed in halftone (F14). If it is the command to be output at, the display control CPU 8 turns on the halftone control port I (L level) (F1
5).

In this case, the voltage of the digital output signal output from the display IC 10 and attenuated by the attenuator 11 is almost halved by the resistor R ₁ provided on the halftone control port I, and the halftone display output data is output. To the synthesis circuit 4 (F17).

If the data to be displayed is not halftone (F14), the halftone control port I is turned off (H level) (F16), and the conventional display I is used.
The signal output of C10 is output to the synthesis circuit 4 via the attenuator 11 without being attenuated (F17).

The display IC 10 outputs a binary digital signal such as 0 volt when there is no RGB output signal and 5 volt when there is an output signal, and R
Eight colors could be displayed by combining the GB signals, but since the digital output signal of the attenuator 11 can be almost halved and output by the signal output from the halftone control port I, each RGB signal is simply 0. bolt,
As three-value digital output signals of 5 volts and about 2.5 volts, 16 colors can be displayed in combination.

Further, although the halftone control port I in this embodiment controls three types of RGB output signals at the same time, a dedicated control port for separately controlling each of the three types of output signals is provided. It is possible to display 48 colors by further increasing the combination of RGB signals.

Regarding the resistor R ₁ , in this embodiment, the signal output of the attenuator 11 has been halved, but it need not be halved.

[0014]

As described above, in the digital display device of the present invention, the display control CPU is provided with the halftone control port and the output side of the display IC is provided with the attenuator, and the display IC is a digital IC. Even if there is no halftone function, the digital output signal of the display IC can be almost halved by the signal of the halftone control port to enable halftone display.
Further, since the conventional high-priced analog display IC having the halftone function is not used, the digital display device of the present invention has an advantage that the cost of various electronic devices can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram of a television receiver that is an embodiment of the present invention.

FIG. 2 is a flowchart showing a process for halftone display.

[Explanation of symbols]

 4 Synthesis Circuit 6 Control Microcomputer 8 Display Control CPU 9 Horizontal Sync Counter 10 Display IC 10A Character Generator 10B Video RAM 10C Signal Output Circuit 11 Attenuator

Claims (1)

[Claims] 1. A digital display device comprising a display IC and a display IC control microcomputer, wherein the display IC control microcomputer is provided with a halftone control port, and an attenuator is provided at a digital output terminal of the display IC. And a signal output from the halftone control port to control the attenuation amount of the attenuator so that the digital output for display can be substantially halved.