EP0185328A2

EP0185328A2 - Display control system

Info

Publication number: EP0185328A2
Application number: EP85115913A
Authority: EP
Inventors: Takatoshi Ishii
Original assignee: ASCII Corp
Current assignee: ASCII Corp
Priority date: 1984-12-13
Filing date: 1985-12-13
Publication date: 1986-06-25
Anticipated expiration: 2005-12-13
Also published as: DE3586623T2; EP0185328A3; DE3586623D1; EP0185328B1

Abstract

A display control system for use in a display system (10) having digital interfaces is disclosed which, when software using color display is executed (CG33,14 & 15) in the display system (10) with digital interfaces, is capable of distinguishing the display contents thereof from one another. Specifically, the display control system (10) is adapted to generate a given number of pieces of brightness information different from one another in duty correspondingly to respective pieces of color code information or brightness code information, to set up the dots of a display screen (20) in two mutually adjacent areas, and to shift the above-mentioned brightness information to be given to one of the above-mentioned areas from the above-mentioned brightness information to be given to the other area in phase. Also, the above-mentioned code information may be converted into hatch patterns correspondingly to the dot and raster positions in display means (20).

Description

The present invention relates to a display control system provided with digital interfaces.
Current display systems of both monochrome and color monitors can have either digital or analogue interfaces.
In general, the monochrome monitor system using a CRT or liquid crystal is more common than the color monitor system, because the former is less expensive than the latter. On the other hand, however, since the use of the color monitor system is gradually increasing, a large amount of software using a color display is now found on the market.
In the display system with digital interfaces, when the software utilizing the color display is executed by the conventional system using a monochrome monitor, there is a problem in that the display contents thereof can not be distinguished from one another. This is because the above-mentioned conventional monochrome monitor system is only able to perform a black-and-white display and not discriminate between display colors.
Also, in order to be able to distinguish colors from one another in the system using a digital interface monochrome monitor, color code information may be read out prior to writing into a VRAM, the read-out color code information may be converted into a hatch pattern signal, and then the converted hatch pattern signal may be written again into the VRAM. However, there arises another problem that other kinds of software are necessary to realize this.
In view of the above-mentioned circumstances in the prior art, an object of the present invention is to eliminate or at least mitigate the drawbacks found in the above-mentioned conventional display control system.
Another object of the invention is to provide an improved display control system for use in a display system with digital interfaces, which, when software utilizing a color display is executed in the above-mentioned display system, is capable of distinguishing the resultant display contents from one another.
According to the invention, different kinds of brightness information having duties different from one another are issued correspondingly to different kinds of color code information or brightness code information respectively; dots on a display screen are established in two areas which are located adjacently to each other; and, the above-mentioned brightness information to be given to one of the above-mentioned two areas is shifted in phase with the brightness information to be given to the other area.
Also, correspondingly to dot positions and raster positions in display means, the above-mentioned code information may also be converted into a hatch pattern.
The above and other related objects and features of the invention will be apparent from a reading of the following description of preferred embodiments of the invention with reference to the accompanying drawings, in which:

Fig. 1 is a general view of one embodiment of the present invention;
Fig. 2 is a table to illustrate in part 1/0 registers included in a display system shown in Fig. l;
Fig. 3 is a block diagram of ;another embodiment of the invention;
Fig. 4 is a view to illustrate the relationship between the code and brightness information in the above embodiment;
Fig. 5 is a view to illustrate a portion of display means suitable for use in carrying out the invention;
Fig. 6 is a table to illustrate the patterns of a ROM shown in Fig. 3;
Fig. 7 is a block diagram of a further embodiment of the invention;
Fig. 8 is a table to illustrate the patterns of a ROM shown in Fig. 7;
Fig. 9 is a block diagram of another embodiment of the invention;
Fig. 10 is a block diagram of a further embodiment of the invention;
Fig. 11 is a view to illustrate an embodiment of hatch pattern conversion means suitable for use in carrying out the invention;
Fig. 12 is a view to illustrate 8 patterns respectively provided by the above hatch pattern conversion means; and,
Fig. 13 is a table to illustrate the respective patterns in a hexadecimal notation.

Referring first to Fig. 1, there is illustrated a block diagram of an embodiment of the invention.
A display system 10 is a system which controls the display of an LCD or a CRT. Display System 10 includes a CRT controller 11, a driver 12 for amplifying data signals, an attribute graphic 13, an alpha 14, a color selector 15, a color palette 16 for performing a color conversion, a composite color generator CG, and a mode select register 71. CRT Controller 11 is used to generate a timing signal in accordance with a parameter when it is set. Color Selector 15 outputs a 4-bit digital signal for specifying a color, when a color CRT is used as display means 20.
Composite Color Generator CG has code information/ brightness information conversion means CG1, CG2, and CG3. These code information/brightness information conversion means CG1, CG2, CG3 respectively generate the brightness information of duties different from each other correspondingly to the respective color code information or brightness code information, and also shift the above-mentioned brightness information in a predetermined area from the brightness information in other areas in phase. The shift amount is about 180 degrees. Display System 10 further includes an internal control register 18 and circuits shown in Fig. 1.
For Display Means 20, a CRT or an LCD can be used.
Externally of Display System 10, there are provided a VRAM (a RAM for video) 30 consisting of a DRAM or a SRAM, an address latch 31 for latching an address signal from a CPU, a data latch 32 for latching data from Display System 10, a character generator 33 for converting character information into dots according to a signal from Data Latch 32, and an external control register 34 for receiving data from Internal Control Register 18.
Next, we will give an outline of the operation of the above-mentioned embodiment of the invention.
Referring here to Fig. 2, there is illustrated a table to show a portion of an I/O register contained in Display System 10. This I/O register is provided with a plurality of register functions which differ from one another.
Here, to display characters on the CRT as Display Means 20, data signals from the CPU (not shown) are once written into VRAM via Driver 12. Display System 10 reads out VRAM 30 repeatedly to the synchronization/scanning of the CRT. The thus-read-out data are latched by Data Latch 32. The data are converted into dots by Character Generator 33 and Alpha 14, then converted into color signals by Color Selector 15 and finally sent to the CRT. On the other hand, when it is desired to perform a color conversion, Color Palette 16 is used. The above-mentioned color signals are D/A converted by Composite Color Generator CG and the resultant Y signals are sent to the CRT. In this case, since Display Means 20 is not a color monitor, the execution of the above-mentioned color conversion operation means the brightness conversion.
On the other hand, when the LCD is employed as Display Means 20, the D/A conversion of the color signals in Composite Color Generator CG is not carried out, but other operation is used to control the display of the LCD.
Referring now to Fig. 3, there is illustrated a block diagram of an example of code information/brightness information conversion means employed in the invention.
In this figure, EXOR Circuit 50 is an exclusive-or operation circuit which receives a line count 0 signal and a dot count 0 signal. Line Count 0 Signal is LSB (0-bit signal) of a line count signal, while Dot Count 0 Signal is LSB (0-bit signal) of a dot count signal.
When the output of EXOR Circuit 50 is "0", then signals shown by solid lines in Fig. 4 are output from ROM51 and areas shown by oblique solid lines in Fig. 5 are displayed. When the output of EXOR Circuit 50 is "1", then signals shown by broken lines in Fig. 4 are output from ROM51 and areas shown by oblique broken lines in Fig. 5 are displayed. EXOR Circuit 50 is adapted to create so-called "checkered" selection switching signals on Display Means 20.
ROM 51 is adapted to output the brightness information of different duties from one another correspondingly to the respective color code information AO, A1, A2 received from Color Palette 16. The relationship between the above-mentioned color code information and brightness information is illustrated in Fig. 4.
For example, when the color code information is "110", if the output of EXOR Circuit 50 is "O", then a parallel signal (shown by a solid line) in which only the first frame thereof is "Low" is output, while if the output of EXOR Circuit 50 is "1", then a parallel singal (shown by a broken line) in which only the fourth frame thereof is "Low" is output.
Selector 52 is adapted to output the signal out of the output signals of ROM 51 that corresponds to the number of frames. In the above-mentioned case, 8 frames 0 - 7 are used and the frame number is determined according to frame count 0, 1, 2 signals. In Fig. 3, reference CG1 designates code information/brightness information conversion means.
Next, we will describe the operation of the above-mentioned embodiment of the invention.
A given piece of color code information is output from Color Palette 16 and, according to this given color code information, brightness code information is output, as shown in Fig. 4. In this case, if the output of EXOR Circuit 50 is "0", "1", then the signals are output in the wave forms respectively shown by the solid and broken lines in Fig. 4. And, Selector 52 outputs a 1-bit signal in accordance with the then frame, which signal is then transmitted to Display Means 20.
Therefore, in the above embodiment, even when a certain dot is being displayed with the same brightness at a certain instance, if the then frame is different, the average brightness of the dot is also different so as to be able to display an intermediate brightness. And, the intermediate brightness is made to correspond to its associated color and thus, even in a monochrome monitor, differences between colors can be recognized visually. Also, since every dot of Display Means 20 is displayed by a signal which is different in phase, a flicker is also 180 degrees out of phase so that flickers cancel each other to become quiet.
Fig. 6 is a table to illustrate the patterns of ROM 51 shown in Fig. 3.
Now, in Fig. 7, there is illustrated a block diagram of a second embodiment of the invention.
In this embodiment, a single ROM 51a is used to take the place of EXOR Circuit 50 and ROM 51 in Fig. 3. In Fig. 7, reference CG2 designates code information/brightness information conversion means.
The patterns of the above-mentioned ROM 51a are shown in Fig. 8.
In Fig. 8, reference characters A, B designate the same portions as with A, B in Fig. 6, respectively.
Now in Fig. 9, there is illustrated a block diagram of a third embodiment of the invention.
In this embodiment, a single ROM 51b is employed to take the place of ROM 51a and Selector 52. In this figure, reference CG3 designates code information/brightness information conversion means.
It should be noted that the operations of the embodiments illustrated in Figs. 7 and 9 are similar to that of the embodiment in Fig. 3.
Although in the foregoing explanation the code information/brightness information conversion means or circuit is composed of a ROM and an EXOR circuit for purposes of generalization of the description, it is also possible to make an equivalent circuit by using other elements such as AND, OR, INV and the like.
Referring now to Fig. 10, there is illustrated a block diagram of a fourth embodiment of the invention.
In this figure, Code Information Output Circuit 110 is adapted to output color code information or brightness code information in accordance with the memory contents of VRAM (Video RA14) 120. In this embodiment, the output information of Code Information Output Circuit 10 is output in the form of 3-bit signals.
Batch Pattern Conversion Means 130 converts the above-mentioned code information into hatch patterns and then outputs them bit by bit. In this case, Hatch Pattern Conversion Means 130 outputs signals in accordance with the dot position and line position (raster position) in CRT 140.
In Fig. 11, there is illustrated an embodiment of Hatch Pattern Conversion Means 130 employed in the above embodiment of the invention.
Hatch Pattern Conversion Means 130 has 8 patterns (pages) which are different from one another in gradation. The examples of these 8 patterns are illustrated in Fig. 12. Each of the 8 patterns is composed of a character box including 8 dots x 8 dots: the portions thereof shown by oblique lines represent black dots on CRT 140; and, the portions with no oblique lines stand for white dots on CRT 140.
In accordance with the above-mentioned color code in- foramtion, one pattern is selected out of the 8 patterns and, in accordance with the lower 3 bits of the then line count signal, one line is selected out of eight lines 0 - 7. At the same time, in accordance with the lower 3 bits of a dot count signal, one dot is selected out of eight dots 0 - 7.
In this way, a specified signal is output from Selector 131, and then a next signal which corresponds to a next dot will be output from Selector 131 similarly.
In Fig. 13, the above-mentioned patterns are expressed in a hexadecimal notation, respectively.
Next, we will describe the operation of the embodiment illustrated in Fig. 10.
One of the above-mentioned patterns 0 - 7 is first selected according to a certain piece of the color code information since the respective pieces of the color code information (or the brightness code information) correspond to the respective patterns 0 - 7 illustrated in Fig. 12.
For example, it is assumed that a pattern shown in Fig. 11 (pattern 1) is selected. Also, it is supposed that a position on CRT 140 is being scanned in which the lower 3 bits of the line count signal are "0" and the lower 3 bits of the dot count signal are "0". In this case, from Fig. 11, Hatch Pattern Conversion Means 130 then outputs "0" and a white color is displayed on CRT 140. Also, in case when another position on CRT 140 is being scanned in which the lower 3 bits of the line count signal are "0" and the lower 3 bits of the dot count signal are "3", from Fig. 11, Hatch Pattern Conversion Means 130 then outputs "1" and a black color is displayed on CRT 140.
In this way, the dots are converted into the associated patterns dot by dot. When the lower 3 bits of the dot count signal become "7", then they become "0", so that the above-mentioned operations are repeated again. Similarly, when the lower 3 bits of the line count signal become "7", then they become "0", so that the above-mentioned operations are repeated again. When the color code information is varied somewhere in the movement of the above-mentioned dots or lines (that is, halfway along the scanning), Hatch Pattern Conversion Means 130 is operated in accordance with the pattern that corresponds to the color code information.
Therefore, the hatch patterns to be displayed on CRT 140 are varied according to the color code information and such variations of the hatch patterns occur in dots. As a result of this, when software for colors is applied in a monochrome monitor, there is provided an advantage that differences between the colors can be recognized accurately.
Now, it should be noted that the unit of the hatch patterns may be arbitrary in size, that is, it may be m dot(s) x n dot(s) (m, n are arbitrary integers, respectively) in size. Also, the number of kinds of the hatch patterns may be other than 8, and the batch patterns may comprise other arbitrary designs than those illustrated herein.
Further, although in the embodiment of Fig. 11 the signal is selected in accordance with the dot count signal, alternatively, either of the other elements (the color code information or the line count signal) may be selected. In addition, a liquid crystal may be used in place of CRT 140.
As described hereinbefore, the present invention has two effects that it has software compatibility and that the time necessary for its processings can be reduced, because it is capable of recognizing the differences between colors even in a system using a digital interface monochrome monitor.

Claims

1. A display control system for use in a display system having digital interfaces, said display control system characterized by:

code information/brightness information conversion means (CG1) for generating a given number of pieces of brightness information different from one another in duty correspondingly to respective pieces of color code information or brightness code information;

area setting means (52) for setting up dots on a display screen in two mutually adjacent areas; and

phase shift means (CG1) for shifting said brightness information to be given to one of said two areas from said brightness information to be given to the other in phase.

2. A display control system as defined in Claim 1, wherein the amount of shift provided by said phase shift means (CG1) is about 180 degrees.

3. A display control system as defined in Claim 1 or 2, wherein said area setting means is adapted to set up areas such that the horizontally mutually adjacent areas of said display screen (20) differ from each other and the vertically mutually adjacent areas of said display screen differ from each other.

4. A display control system characterized by:

code information output means (110) for outputting color code information or brightness code information; and

hatch pattern conversion means (130) for converting said code information output from said code information output means to hatch patterns corresponding to the dot and raster positions in display means (20).

5. A display control system defined in Claim 4, wherein said hatch pattern conversion means (130) comprises a conversion circuit adapted to input said code information, dot count signals and line count signals, convert them to 1-dot signals, and output said 1-dot signals.

6. A display control system defined in Claim 4 or 5, wherein each of said hatch patterns in said hatch pattern conversion means (130) is set in m (m is an integer) dot(s) x n (n is an integer) dot(s).

7. A display control system defined in Claim 4, 5 or 6, wherein each of said hatch patterns in said hatch pattern conversion means (130) is set in a character box.

8. A display control system defined in any one of claims 4 to 7, wherein said display means (20) comprises a CRT or liquid crystal.