JPH02204781A - Device for composing color signal - Google Patents

Abstract

PURPOSE:To rewrite color data without generating noise on a display screen during the period of display by providing plural address terminals and data terminals in a lookup table. CONSTITUTION:A color code from a display period image storage control part is temporarily stored in the 1st latch 9 through an input terminal 8. A signal passed through the 1st decoder 17 selects one of addresses in the lookup table 16 and reads out color data and the color data are converted into analog data by respective D/A converters 2 to 4 for R, G, B and the analog data are outputted from terminals 5 to 7. In order to rewrite data in the table 16, data from a microprocessor are temporarily stored in the 2nd latch 11 through a terminal 10. Respective color data are temporarily stored in the 3rd latch 13 and data can be written in the address of the table 16 selected by the 2nd decoder 18 without generating noise.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color signal synthesis device for displaying color data in workstations, personal computers, word processors, and the like.

2. Description of the Related Art Displays, which play an important role as man-machine interfaces for personal computers, are increasingly equipped with color display functions. Moreover, there is a tendency for color displays to be displayed in multiple colors that are close to natural colors. On the other hand, CR, which is a typical display
In addition to T, flat panel displays such as liquid crystal displays and plasma displays are also used.

The above-mentioned flat panel display has been commercialized as a display having a monochrome display function, but there is a tendency in the future to have a multicolor display function.

A conventional color composition device for CRT will be explained below.

FIG. 3 is a block diagram of a conventional color composition device for CRT. 1 is a lookup table that stores digital color data, 2.3.4 are red (R) and green (
G), D/A converter for converting blue (B) digital color data to analog color data, 5
, 6.7 are output terminals for each color data of R, G, and B, 8 is a color code data input terminal inputted from the image storage control unit that stores image data, and 9 is a temporary input terminal for color code data. 10 is an address data input terminal of the lookup table 1 which is input from the microprocessor, 11 is a second latch which temporarily stores address data, and 12 is a lookup table which is input from the microprocessor. 13 is a third latch that temporarily stores color data; 14 is either the color code data of the first latch 9 or the address data of the second latch 11; a selector that selectively selects and outputs 15
is a decoder for converting binary color code data and address data into lookup table 1 addresses.

Regarding the color composition device configured in this way, next,
Let's explain its operation.

First, the operation of writing color data into the lookup table 1 will be described.

Address data of the look-up table 1 is inputted from the microprocessor through the address input terminal 1° to the second latch 11 and is temporarily stored. Assuming that this address data is composed of n bits, the address data is passed through the selector 14 and decoded by the decoder 15, and the address specified by the address data among the 20 addresses in the lookup table is set.

On the other hand, color data input terminal 12 from the microprocessor
The color data to be stored in the look-up table 1 through is input into the third latch 13 and -temporarily stored. Assuming that this color data is composed of m bits each for R, G, and B, the third latch 13 is
Temporarily stores 3m bits of color data. This 3m-bit color data is stored at the address of the lookup table 1 set by the decoder 15. Repeat the above write operation to write lookup table 1
Color data of 3m bits is written to address 2n, and color data of 2n×3m bits is stored. In other words, the total color data has 2311 colors.
Among them, color data of 2n colors is written into the lookup table 1. When rewriting the color data in the lookup table, the above write operation is performed again, and color data for new 20 colors from among the 23 colors are written.

Next, the read operation of lookup table 1 will be described.

Color code data is temporarily stored in the first latch 9 from the image storage control section through the color code data input terminal 8. This data has an n-bit configuration, is decoded by a decoder 15 via a selector 14, and among the 20 addresses of the lookup table 1, the address specified by the color code data is set. Then, the color data at the specified address in lookup table 1 is output. This color data is R, G,
Each B has an m-bit configuration, and each has a D/A converter 2.
, 3.4, are converted into analog signals, and are output as R, G, and B analog signals from analog output terminals 5 and 6.7, respectively.

The above is the read operation of lookup table 1,
One readout operation is performed for one pixel. A high-speed color compositing device is required to support high-definition color displays, so the color compositing device shown in Fig. 2 is
It is realized with one IC (integrated circuit).

Problems to be Solved by the Invention However, in the conventional configuration described above, the lookup tape has only one address terminal, so when rewriting the contents of the lookup table, the address terminal must be switched to the microprocessor side. CR
The address of the lookup table is changed to C during the display period of T.
There was a problem in that noise was generated on the display screen when switching to the PU side.

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned conventional problems, and an object of the present invention is to provide a color signal synthesis device that can rewrite data in a look-up table without generating noise on a display screen.

Means for Solving the Problems To achieve this object, the color signal synthesis device of the present invention is comprised of a look-up table having a plurality of address terminals and a plurality of data terminals.

Function: With this configuration, the lookup table can read and write data at the same time without switching address terminals.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a block diagram of a color signal synthesis device according to an embodiment of the present invention. In Figure 1, 16 is 2
A lookup table 17 has two address terminals, and a lookup table 17 stores color code data in the first
A first decoder 18 for converting into an address is a decoder for converting address data input from the microprocessor into a second address of the lookup table 16. Note that 2.3.4 is a D/A converter for converting red (R), green (G), and blue (B) digital color data into analog color data, respectively;
5.6.7 are analog output terminals for R, G, and B color data, respectively; 8 is a color code data input terminal input from the image storage control unit storing image data;
9 is a first latch that temporarily stores color code data, 10 is an address data input terminal input from the microprocessor, 11 is a second latch that temporarily stores address data, and 12 is input from the microprocessor. A color data input terminal 13 is used to store color data in a look-up table 16, and a third latch 13 temporarily stores color data, which are the same as those in the conventional example.

The operation of the color signal synthesis apparatus of this embodiment configured as described above will be described below.

First, during the display period, an n-bit color code is temporarily stored in the first latch 9 through the input terminal 8 from the image storage control section. The signal decoded by the first decoder 17 selects one of the two addresses of the lookup table 16 and reads color data from the lookup table 16. The read color data is converted into analog data by the R2G and B D/A converters 2.3.4, and output from the analog output terminal 5°6.7.

When the color data of the lookup table 16 is to be rewritten next time, the address data of the lookup table 16 output from the microprocessor is temporarily stored in the second latch 11 through the address input terminal 10.

The address data stored in the second latch 11 has an n-bit configuration, and the second decoder 18 selects one of the 20 addresses in the look-up table 16. The third latch 13 temporarily stores RlG and B color data as in the conventional example, and writes the color data to the address of the lookup table 16 selected by the second decoder 18. At this time, the display controller side reads the display color data through an address terminal different from the microprocessor side, and display control is performed without being influenced by the microprocessor.

As described above, according to this embodiment, by providing two address terminals for the lookup table 16, the color data in the lookup table 16 can be rewritten without generating noise on the display screen during the display period. Can be done.

Effects of the Invention According to the present invention, excellent color signal synthesis is achieved in which color data can be rewritten without generating noise on the display screen during the display period by having a plurality of lookup table address terminals and a plurality of data terminals. The device can be realized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a color signal synthesis apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional color signal synthesis apparatus. 1... Lookup table, 2...
D/A converter (R), 3...D/A converter (G), 4...D/A converter (B),
5...Analog output terminal (R), 6...
・Analog output terminal (G), 7... Analog output terminal (B), 8... Color code data input terminal, 9... First latch, 10... ...Address data input terminal, 11...Second controller,
12...Color data input terminal, 13...
...Third latch, 14...Selector, 15...
. . . decoder, 16 . . . lookup table with two address terminals, 17 . . . th decoder, 18 . . . second decoder.

Claims (1)

[Claims] The microprocessor and display controller each have multiple address terminals and data terminals that can be read and written at the same time.
A color signal synthesis device comprising: a lookup table for storing the color data of item B); and a D/A converter for converting the digital color data of the lookup table into analog color data.