JPS60202477A - Display unit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a display device for displaying a display video signal such as a CRT controller.

Conventional Structure and Problems When displaying on a CRT (cathode ray tube) display, it is necessary to sequentially read out the contents of a refresh memory in synchronization with screen scanning and convert them into video signals. A conventional display device using a CRT controller that performs these operations is shown in FIG.

CRT controller 101 supplies an address signal corresponding to the screen display position to refresh memory 103 via line 102 in synchronization with screen scanning. Refresh memory 103 supplies display data at the corresponding address to CRT controller 101 via line 104.

The CRT controller 101 generates a display video signal according to the content of display data, and outputs the signal to the CRT 1 via a line 106.
It is supplied to o6. In this conventional example, the display data uses 16 bits for displaying 8 dots on the screen, with 8 pits representing the dot pattern and the other 8 pits representing the color of the dots. The relationship with the screen display is shown in FIG.

The display pattern is indicated by pattern data 202 read from the refresh memory 201 at an address corresponding to the screen display, and the color of the dot is indicated by color data 203. Color day 1+: The upper 4 bits of I+7203 indicate the color of the "1" dot in the pattern data, and the lower 4 bits indicate the color of the "1" dot in the pattern data.
0" bit color. In the illustrated example, o1
00'' indicates red, 1oOo'' indicates green, and a dot display such as 206 appears on the display screen 204 of the CRT. However, R indicates red and G indicates green.

This conventional example has a very simple circuit configuration by using a CRT controller, but the screen configuration, ie, the number of dots on the screen, the method of specifying the color of the dots, the correspondence with refresh memory, etc. Limited by functionality.

OBJECTS OF THE INVENTION An object of the present invention is to provide a display device capable of displaying various configurations in addition to the display limited by the functions of a CRT controller.

Structure of the Invention A display device according to the present invention is provided with a generation circuit for generating a sub-display video signal, and is provided with means capable of displaying not only the display data generated by the CRT controller but also the sub-display video signal. be.

DESCRIPTION OF EMBODIMENTS Examples of the present invention will be described below. In FIG. 3, a CRT controller 301 supplies an address signal corresponding to a screen display position to a refresh memory 303 via a line 302 in synchronization with screen scanning. Refresh memory 303 supplies display data at the corresponding address to CRT controller 301 via line 304. The sub-display video signal generation circuit 305 takes in the display data read from the refresh memo I 7303, generates a sub-display video signal, and outputs it to the line 306. CR
The T controller 301 generates a display video signal according to the content of display data and outputs it to a line 307. The switching circuit 308 selects either the display video signal 307 or the sub-display video signal 306 and supplies it to the CRT 309 .

It is also possible to display signals generated by the display video signal generation circuit 306.

More specific examples will be described below.

FIG. 4 shows a block diagram of this embodiment. The CRT controller 401 sends an address signal corresponding to the screen display to the refresh memory 402 on line 40 in synchronization with the scanning of the screen.
3, a strobe signal is provided via line 404, and the display data read out via 8-bit data bus 405 generates a display video signal 420.

As in the prior art example described above, 18-bit display data of 8-bit pattern data and 8-bit color data is read out in two parts, 8 bits each, on line 420 for the 8-dot display of the display video signal.

406 and 407 are two 8-bit latches, which are generated by a timing circuit 408 based on an address signal 403 and a read strobe 404, and take in 8 bits of 16-bit display data from line 4o9°. The captured display data is loaded into shift register 412 by a load signal on line 411 and shifted out by a shift clock output from oscillator 413 on line 414. This shift clock is the frequency divider 41
The frequency is divided by 2 by 6 and becomes the dot clock of the CRT controller 401. The display data shifted out from the shift register 412 to the line 416 is converted into a sub-display video signal by the video signal output circuit 416,
It is output on line 417. Switching circuit 418 is line 4
Select either the display video signal output to line 20 or the sub display video signal output to line 417, and
is supplied to.

In this embodiment, 16 dots of data read out during the 8-bit time of the CRT controller 401 are shifted out using a clock with twice the frequency of the dot clock of the CRT controller 401, and the color data time is shifted out. A total of 16 dots can be displayed using the read 8-bit data.

However, since it is conventionally used to express the color of dots or fresh memory patterns, it cannot express colors. Figure 6 shows the relationship between data and screen display when the display data is the same as the conventional example shown in Figure 2.
" represents white (W), and data "0" represents black (B). The pattern data 502 and color data 503 read from the refresh memory 501 by the address corresponding to the screen display are combined as pattern data. By using a clock with twice the frequency of the conventional example as a dot clock, the 60 MHz clock is displayed at the same display position on the screen 504 as in the conventional example.
A message like 5 will appear.

As described above, in this embodiment, the density of dots displayed on the screen can be doubled by providing a sub-display video signal generation circuit mainly composed of latches and shift registers outside the CRT controller.

In addition to the above embodiment, it is also possible to increase the number of colors that can be expressed by, for example, reconstructing the captured 16-bit data and using it as 4-bit pattern data and 12-bit color data.

Effects of the Invention As is clear from the above embodiments, according to the present invention, CRT
By adding a relatively simple circuit to the outside of the controller, it becomes possible to take a variety of display configurations, which is extremely useful industrially.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional display device, FIG. 2 is a diagram showing its screen display state, FIG. 3 is a block diagram of a display device according to an embodiment of the present invention, and FIG. 4 is a more specific configuration. FIG. 6 is a block diagram showing the screen display state. 301...CRT: 7 controller, 3o3...
... Refresh memory, 305 ... Sub-display video signal generation circuit, 418 ... Switching circuit. Name of agent: Patent attorney Toshio Nakao and one other name
1 Figure 2 Figure 20 / Figure 5 50 / Procedural amendment dated July 23, 1980 Mr. Commissioner of the Japan Patent Office 1 Indication of the case Patent application No. 59992 of 1988 2 Name display device of the invention 3 Person making the amendment Relationship to the incident Patent application Person name 1006 Kadoma, Kadoma City, Osaka Prefecture Name (
582) Matsushita Electric Industrial Co., Ltd. Representative: Toshihiko Yamashita 4 Agent Address: 6, Matsushita Electric Industrial Co., Ltd., 1006 Oaza Kadoma, Kadoma City, Osaka Prefecture Contents of amendment (1) Specification, page 6, line 6 Correct "read out through," to "supply through and read out." (Moan) Correct "18 bits" on the 13th line of page 5 to "16 bits" and change it to 1. ]. (4) Correct [416] on page 6, line 8 of the same page to "421". (6) Correct figure 4 of the drawing as shown in the attached sheet〇Figure 4 20

Claims (1)

[Claims] a refresh memory that stores screen display data; a CRT (cathode ray tube) controller that reads display data from the refresh memory in synchronization with screen scanning and generates a display video signal; A display device comprising: a sub-display video signal generation circuit that captures display data and generates a sub-display video signal.