JPS645308B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a color CRT display device, and more particularly, to a color CRT display device that calculates the mixing ratio of the three primary colors red, green, and blue from a color table memory based on color data stored in an image memory. Color that can be read out and displayed as colored figures on a CRT display
Regarding CRT display devices.

Description of Prior Art FIG. 1 is a block diagram of the main parts of a color CRT display device, which is the background of the present invention, and FIG. 2 is a waveform diagram for explaining the operation of FIG. 1.

First, in Figure 1, image memory 1 is a CRT
It includes a storage area corresponding to each dot of one screen of a display (not shown), and stores color data in each storage area. Then, by sequentially applying clock pulses as shown in FIG. 2 within one horizontal scanning period, color data corresponding to each dot is read out. The read color data is latched into register 2 at timing t1 of the leading edge of the clock pulse. The color data latched in register 2 is applied to color table memory 3. The color table memory 3 stores 4-bit multi-gradation color codes for each of red, green, and blue, and when color data is latched in the register 2, the color code corresponding to the color data is red, green, and blue.
Outputs a 4-bit color code for each green and blue color. Each red, green, and blue color code output from the color table memory 3 is stored in registers 4 to 6 at timing t2 of the leading edge of the next clock pulse.
and is applied to a CRT display (not shown).

Incidentally, since the scanning time of a conventional CRT is about 25 nsec per dot, it is sufficiently accessible even if a commercially available IC memory is used as the color table memory 3. However, in order to obtain high-quality color graphics, it is necessary to increase the scanning speed of each dot on a CRT display. However, since there is a limit to the time that IC memory can be accessed, increasing the scanning speed of each dot
There was a problem in that the color code output from the color table memory 3 was not stable and good color figures could not be displayed on the CRT.

Purpose of the invention Therefore, the main purpose of this invention is to
Using IC memory as color table memory,
An object of the present invention is to provide a color CRT display device capable of displaying stable color graphics even when the scanning speed of each dot is increased.

Structure of the Invention To summarize the present invention, color data is sequentially read out from the image storage means in synchronization with the first clock pulse corresponding to each dot, and based on this color data, red, red, red, etc. are read from the first color code storage means.
A multi-gradation color code specifying the three primary colors of green and blue is read out in synchronization with a second clock pulse having a period twice that of the first clock pulse. Further, the color code is read out from the second color code storage means in synchronization with a third clock pulse having a phase difference corresponding to a cycle of one dot with respect to the second clock pulse, and the color code is read out from the second color code storage means The color code read from
The color code read from the color code storage means is alternately output in synchronization with the first clock pulse.

The invention will be explained in more detail below along with embodiments shown in the drawings.

FIG. 3 is a block diagram of one embodiment of the present invention. First, the configuration will be explained with reference to FIG. The image memory 1 used as the image storage means is the same as that shown in FIG. 1 described above. The color data stored in the image memory 1 is read out in synchronization with the first clock pulse applied from the clock pulse generation circuit 20. This first clock pulse has a period corresponding to each dot on the screen of the CRT display.
A first register 7, a color table memory 8 as a first color code storage means, registers 9 to 11 as a third register, a second register 15, and a color table memory 16 as a second color code storage means. and registers 17 to 19 as fourth registers correspond to register 2, color table memory 3, and registers 4 to 6 shown in FIG. 1, respectively. Register 7 and registers 9 to 11 temporarily store color data or color codes in synchronization with the second clock pulse output from clock pulse generation circuit 20. This second clock pulse is chosen to have a period twice that of the first clock pulse. The other register 15 and registers 17 to 19 temporarily store color data or color codes in synchronization with the third clock pulse. This third clock pulse has the same period as the second clock pulse, but its phase lags the second clock pulse by one dot period. The color codes temporarily stored in registers 9 to 11 and 17 to 19 are applied to registers 12 to 14 as output means. These registers 12 to 14 temporarily store and alternately output the color codes output from registers 9 to 11 and registers 17 to 19, respectively, in synchronization with the first clock pulse.

FIG. 4 is a waveform diagram of each part of FIG. 3.

Next, the specific operation of one embodiment of the present invention will be described with reference to FIGS. 3 and 4. The image memory 1 sequentially reads out the color data shown in FIG. 4b at the leading edge of the first clock pulse CP1 as shown in FIG. 4a. This color data A is given to registers 7 and 15. The second clock pulse applied to the register 7 has a period twice that of the first clock pulse as shown in FIG.
Color data A is stored as shown in Figure e. At this time, as shown in FIG. 4d, the third clock pulse applied to the other register 15 is delayed in phase by a period corresponding to one dot than the second clock pulse, so color data A is not stored. . Then, at the first leading edge of the first clock pulse, color data B is read out from the image memory 1, and the register 15 temporarily stores the color data B at the leading edge of the third clock pulse, as shown in FIG. 4f. do. One color table memory 8 successively outputs a multi-gradation color code a of red, green, and blue corresponding to the color data A stored in the register 7.

Similarly, when color data B is stored in the register 15 of the other color table memory 16, the color code b corresponding to the color data is stored.
Read out. Then, the image memory 1 reads out the color data C at the leading edge of the third first clock pulse. At this time, at the leading edge of the second clock pulse, registers 9 to 11 latch color code a corresponding to color data A that has been read out from color table memory 8. Therefore, color code a latched in registers 9-11 is applied to registers 12-14. Registers 12-14 then latch and output color code a at the leading edge of the first clock pulse.

Note that at the leading edge of the second clock pulse, the register 7 registers the color data C read out from the image memory 1.
Remember. At the leading edge of the fourth pulse of the first clock pulse, color data D is read from the image memory 1, and at the leading edge of the third clock pulse, registers 17 to 19 latch the color code b read from the color table memory 16. do. The color code b is then stored in registers 12-14 and output at the leading edge of the first clock pulse. That is, the registers 12 to 14 output the color code a outputted from the color table memory 8 in synchronization with the first clock pulse as shown in FIG. The color code b read from is output. Note that at the leading edge of the third clock pulse, the register 15 stores the color data D read out from the image memory 1. Color code d corresponding to color data D is read out from color table memory 16 and latched into registers 17 to 19 at the timing of the next leading edge of the second clock pulse.

In this way, the color codes read from the first color table memory 8 and the second color table memory 16 are stored in the registers 9 to 11.
and 17 to 19, and can be temporarily stored in registers 12 to 14, and can be outputted alternately in synchronization with the first clock pulse corresponding to the dot on the screen.

Effects of the Invention As described above, according to the present invention, the second and third clock pulses applied to the first and second color code storage means have a period twice that of the first clock pulse applied to the image storage means. Therefore, even if the frequency of the dots on the CRT screen is increased,
Even if conventional IC memory is used as a color code storage means, it can be sufficiently accessed and high quality color graphics can be displayed on a CRT display.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the main parts of a conventional color CRT display device. FIG. 2 is a waveform diagram for explaining the operation of FIG. 1. FIG. 3 is a block diagram of one embodiment of the present invention. FIG. 4 is a waveform diagram of each part of FIG. 3. In the figure, 1 is an image memory, 7 is a first register, 8 is a first color table memory, 9 to 11 are third registers, 12 to 14 are output side registers, 15 is a second register, 16 is the second color table memory, 17 to 19 are the fourth color table memory.
The register 20 represents a clock pulse generation circuit.

Claims (1)

[Scope of Claims] 1. In a color CRT display device that displays color figures as a plurality of dots on a CRT screen, a first clock pulse corresponding to the period of each dot, and a period of the first clock pulse. a second clock pulse having a period twice that of the first clock pulse;
Clock pulse generating means for generating a third clock pulse having twice the period and having a phase difference corresponding to a period of one dot with respect to the second clock pulse, comprising a storage area corresponding to all dots on the CRT screen. , an image storage means for storing color data of a figure to be displayed therein and sequentially outputting the color data dot by dot in response to the first clock pulse; a first color code storage means that stores in advance a color code corresponding to the color data read out from the image storage means, and reads out the color code in synchronization with the second clock pulse; a second color code storage means for storing a color code in advance as a color code and reading out a color code corresponding to the color data read from the image storage means in synchronization with the third clock pulse; and 1. A color CRT display device, comprising output means for alternately outputting each color code output from the color code storage means in synchronization with the first clock pulse. 2. The first color code storage means includes a first register that temporarily stores the read color data in synchronization with the second clock pulse, and the second color code storage means includes a first register that temporarily stores the read color data in synchronization with the second clock pulse. 2. A color CRT display device as claimed in claim 1, including a second register for temporarily storing color data in synchronization with said third clock pulse. 3 a third register for temporarily storing the color code read from the first color code storage means in synchronization with the second clock pulse; and a third register for temporarily storing the color code read from the second color code storage means; 2. A color CRT display device as claimed in claim 1, including a fourth register for temporary storage in synchronization with a third clock pulse.