High resolution display system and method of using same

What is claimed is:

1. A display control arrangement, comprising:

means responsive to a series of input intensity level signals indicative of individual ones of a large number of different incoming intensity levels for determining an individual unique one of another large number of a series of different M by N pixel matrix arrays of gray scale intensity level patterns corresponding to a given incoming intensity level;

each one of said patterns having two different desired gray scale intensity levels to help facilitate a blending gradation of color shading levels between pixel images of the same primary color but being generated in response to slightly different incoming intensity levels, each one of the two different gray scale intensity levels being less than its corresponding incoming intensity level, said two different gray scale intensity levels differing by at least one gray scale intensity level;

means for determining an individual one of said two different desired gray scale intensity levels for a selected pixel element in a determined pattern; and

means responsive to the determined desired gray scale intensity level of said two different gray scale intensity levels for said selected pixel element for causing the selected pixel element to be activated selectively to facilitate pixel image perception at the determined desired gray scale intensity level;

whereby said patterns of two different gray scale intensity levels for any single incoming intensity level signal cause adjacent pixel images of the same primary color but having somewhat different gray scale intensity levels to blend in a subtle gradation of intensity levels.

2. A display control arrangement, according to claim 1, wherein said pixel control means includes:

a plurality of pattern logic means for producing a plurality of color code signals indicative of desired gray scale color shading levels for at least two separate and distinct primary colors; and

bit map memory means responsive to said pattern logic means for storing said plurality of color code signals in a pattern array for helping to blend color shading levels for the same primary color.

3. A display control arrangement, according to claim 1, further comprising:

interface means coupled to said intensity level means for receiving desired color shading level signals and for formatting said desired color shading level signals to cause the individual color images in the plurality of different color images to be displayed by the display device.

4. A display control arrangement according to claim 1, further comprising:

intensity level means for determining whether or not individual pixel elements in a group of pixel elements are to be activated selectively an average number of times over a large number of consecutive frame time intervals to generate pixel images having substantially the same perceived gray scale color shading level N, where N is one of a large number of different gray scale shading levels; and for determining whether or not individual pixel elements of another group of pixel elements are to be activated selectively an average number of times over said large number of consecutive frame time intervals to generate pixel images having substantially the same perceived gray scale color shading level M, where the gray scale shading level M is another one of said large number of different gray scale shading levels and can be perceived as a substantially different gray scale color shading level than said gray scale color shading level N;

duty cycle means for causing selected individual ones of the pixel elements in said group of pixel elements and individual ones of the pixel element in said another group of pixel elements to be activated selectively an average number of times over a large number of consecutive frame time intervals to generate pixel images defining color shading level patterns to substantially reduce contouring in perceived color shading level differences between pixel images disposed near one another.

5. A display control arrangement, according to claim 4, wherein said duty cycle means includes:

counter means for providing a series of intensity level averaging signals, said averaging signals being arranged in a certain arranged order to help prevent beat patterns in the plurality of different color images;

modifying means for causing said certain arranged order to be changed periodically; and

comparing means for determining whether said desired color shading level signal is greater than a corresponding intensity level averaging signal in said series of signals and for generating a single bit digital signal whenever said desired color shading level signal is greater than said corresponding intensity level averaging signal.

6. A display control arrangement according to claim 5, wherein said certain arranged order is changed during every line in the matrix of sub-pixel elements.

7. A display control arrangement, according to claim 6, wherein said certain arranged order is changed during every one of the frame time intervals in said large number of consecutive frame time intervals.

8. A display control arrangement according to claim 4, wherein said intensity level means includes:

means for determining an individual unique one of a series of duty cycle intensity level patterns, said patterns containing more than two duty cycle intensity levels, wherein at least some of said patterns are each arranged in an M by N pixel matrix array of intensity levels including at least two different duty cycle intensity levels differing by at least one duty cycle intensity level to reduce substantially contouring effects between adjacent pixel images of the same primary color but having different desired incoming intensity levels;

means responsive to the determined duty cycle intensity level pattern for determining an individual one of the duty cycle intensity levels of the determined pattern in accordance with the selected pixel element address location to generate a single duty cycle intensity level signal; and

wherein said duty cycle means includes means responsive to said single duty cycle level signal determined from the selected pattern for causing said selected pixel element to be activated selectively depending upon an overall average large number, substantially greater than eight consecutive frame cycles to cause a pixel image perception at said incoming desired intensity level;

whereby a subtle intensity gradation is achieved in the image to be displayed between groups of pixel images having somewhat different intensity levels.

9. A display control arrangement according to claim 8, wherein said series of duty cycle intensity level patterns includes at least two fixed composite pixel patterns.

10. A display control arrangement according to claim 9, wherein one of said fixed composite pixel patterns includes a group of pixel images having the same color intensity level.

11. A display control arrangement according to claim 9, wherein one of said fixed composite pixel pattern includes a group of pixel images having the same intensity level and a single pixel image having an intensity level substantially less than said group of pixel images.

12. A display control arrangement according to claim 9, wherein one of said fixed composite pixel pattern includes one area of pixel images having the same intensity level and another area of pixel images including at least a single pixel image having an intensity level substantially greater than the first mentioned area of pixel images.

13. A display control arrangement according to claim 9, wherein one of said fixed composite pixel pattern includes a group of pixel images having the same intensity level and a pair of pixel images having an intensity level substantially less than said group of pixel images.

14. A display control arrangement according to claim 9, wherein one of said fixed composite pixel pattern includes one area of pixel images having the same intensity level and another area of pixel images having at least a pair of pixel images having an intensity level substantially greater than the first-mentioned area of pixel images.

15. A display control arrangement according to claim 9, wherein one of said fixed composite pixel patterns includes a single pixel image at said desired color intensity level and a group of pixel images at another desired color intensity level substantially less than said desired color intensity level.

16. A display control arrangement according to claim 9, wherein one of said fixed composite panel patterns includes an area of pixel images including at least a single pixel image at said desired color intensity level and another area of pixel images at another desired color intensity level substantially greater than said desired color intensity level.

17. A display control arrangement according to claim 1, wherein each pattern is arranged in an M by N pixel array.

18. A display control arrangement according to claim 1, further including patterns having only three or four levels of said different desired gray scale intensity levels, where one gray scale level is assigned for the last mentioned pattern.

19. A display control arrangement according to claim 1, wherein the intensity gray scale levels include at least eight desired intensity levels.

20. A display control arrangement, comprising:

truth table means for storing a series of different patterns of groups of gray scale intensity levels, each pattern having at least three desired gray scale intensity levels, each one of said patterns corresponding individually to one of a series of incoming intensity levels, where the individual desired intensity levels within a given pattern are each generally smaller than their corresponding incoming intensity level each group of gray scale intensity levels including two different gray scale intensity levels differing by only one desired gray scale intensity level;

wherein only one of said desired gray scale intensity levels for each pattern is increased by only one gray scale intensity level for each corresponding increasing incoming intensity level value in said series of incoming intensity levels to help facilitate a blending gradation of color shading levels between pixel images of the same primary color but having different incoming intensity levels;

means responsive to a given incoming intensity level for determining one of said patterns for any given display frame cycle;

means for selecting one of said desired gray scale intensity levels of the determined pattern depending upon the address of a given pixel for said any given display frame cycle; and

means for activating said given pixel element at the selected desired gray scale intensity level for said any given display frame cycle;

whereby the color shading level patterns between pixel images having somewhat the same intensity level are blended in a subtle arrangement to substantially reduce contouring in the perceived color shading level differences whenever the last mentioned pixel images are displayed near one another.

21. A display control arrangement according to claim 20, wherein said series of different patterns includes a series of at least four different patterns.

22. A display control arrangement according to claim 20, wherein said series of different patterns includes a series of at least five different patterns.

23. A display control arrangement according to claim 20, wherein said series of incoming intensity levels includes at least eight incoming intensity levels.

24. A display control arrangement according to claim 20, wherein said series of incoming intensity levels includes at least thirty-one incoming intensity levels.

25. A display control arrangement according to claim 20, wherein said series of patterns are recurring over P number of contiguous incoming intensity levels.

26. A display control arrangement according to claim 25, wherein said P number is at least 5.

27. A method for controlling a displayed image to help reduce contouring between pixel images having somewhat different shading levels in the same primary color, comprising:

storing a series of different patterns of groups of gray scale intensity levels, each pattern having at least three desired gray scale intensity levels, each one of said patterns corresponding individually to one of a series of incoming intensity levels, where the individual desired intensity levels within a given pattern are each generally smaller than their corresponding incoming intensity level;

wherein each group of gray scale intensity levels includes two different gray scale intensity levels differing by only one desired gray scale intensity level;

wherein only one of said desired gray scale intensity levels for each pattern is increased by only one level corresponding to each corresponding increasing incoming intensity level value in said series of incoming intensity levels to help facilitate a blending gradation of color shading levels between pixel images of the same primary color but having different incoming intensity levels;

determining one of said patterns for any given display frame cycle in response to a given incoming intensity level;

selecting one of said desired gray scale intensity levels of the determined pattern depending upon the address of a given pixel element for said any given display frame cycle; and

activating said given pixel element at the selected desired gray scale intensity level for said any given display frame cycle;

whereby the color shading level patterns between pixel images having somewhat the same intensity level are blended in a subtle arrangement to substantially reduce contouring in the perceived color shading level differences whenever the last mentioned pixel images are displayed near one another.

28. A method according to claim 27, further comprising:

driving a display device having a matrix of sub-pixel elements to help reduce contouring lines within a plurality of different color images of a common primary color; and

generating energizing signals for driving individual ones of the sub-pixel elements on and off to form one of the plurality of different color images.

29. A method according to claim 28, further comprising:

actuating desired ones of the sub-pixel elements selectively an average number of times over a large number of consecutive frame time intervals to generate sub-pixel images having desired perceived color shading levels.

Description Submit all comments and votes

TECHNICAL FIELD

The present invention relates to a high resolution display system, and a method of using it. The invention more particularly relates to such a system and method for use in video display apparatus, such as a system for projecting video images.

BACKGROUND ART

Many computer systems include a microprocessor unit for processing data and an associated monitor for displaying full color video images. Systems which utilize full color monitors or display units typically include analog or digital interfaces, which provide display control functions for the display unit. In this regard, a typical system employs a computer video signal generating source, such as a VGA video card usually employed in a video drive module of a personal computer system. Such a video drive module typically provides analog RGB signals and/or digital RGB signals with accompanying video formatting signals such as HSYNC and VSYNC signals. Other microprocessors may utilize a video drive module for supplying NTSC composite television signals depending upon the type of monitor employed in the system.

Because of the diversity in the different types and kinds of monitors available for such systems, it has been necessary to employ various types of interfaces to accommodate the different kinds of analog and digital video signals, as well as the different types and kinds of signal formats. In this regard, many different types and kinds of interfaces adapted for coupling a video signal producing device to an associated display unit are known in the prior art. For example, reference may be made to the following U.S. Pat. Nos. 4,531,160; 4,536,856; 4,631,692; 4,760,387; 4,779,083; 4,827,255; and 4,886,343.

U.S. Pat. No. 4,536,856 discloses a video signal display control method and apparatus for providing display control functions for an LCD display device to be attached to an external microprocessor providing output video signals. The apparatus employs an algorithm for processing an output composite video signal to permit display device signal information to be presented to the display device on a scaled-up size or a scaled-down size relative to the physical screen of the LCD display device.

U.S. Pat. No. 4,631,692 discloses another interface adapted for coupling an external microprocessor to an RGB type monitor, where the external microprocessor can only provide a television formatted NTSC signal.

While the above discussed U.S. patents may disclose various types of interfaces for coupling video signal producing devices to various types and kinds of display devices, such interfaces have not proven to be entirely satisfactory for some application, where modern high speed, liquid crystal display monitors are employed.

More particularly, conventional high speed RGB liquid crystal display monitors include a plurality of pixel elements arranged in a matrix array. In this regard, each pixel element in the array, includes an associated group of sub-pixel elements for producing different colors, such as the colors of red, green, and blue. Such sub-pixel elements, are so small in physical size, they are unable to be distinguished by the human eye. Thus, by selecting various combinations of the sub-pixel elements, up to eight different colors can be exhibited by each of the pixel elements. Such a small number of displayable colors however, severely limits the performance of a video signal producing device for generating an analog signal indicative of an infinite number of colors.

Thus, while such a technique of displaying eight different colors on an RGB liquid crystal display monitor may be satisfactory for some applications, it is not entirely satisfactory for those applications requiring a large number of colors to be displayed.

One attempt at solving the above-mentioned color limitation problem, is disclosed in U.S. Pat. No. 4,827,255 where a video signal producing device is coupled to an RGB digital display device for producing up to 3375 or 15.sup.3 different color shades. In this regard, a gray scale technique is employed where a series of display patterns having an area of 2 dots.times.2 lines are displayed repeatedly at a cycle or period of every 8 frames.

While such an interface has proven satisfactory for many applications, such an interface is relatively expensive as it requires the utilization of a multiple panel display device, or a multiple number of drivers for each bit of digital information supplied to the liquid crystal panel. Moreover, such an interface and method suffers from loss of color information and creates a repetitive beat pattern so that displayed images tend to flicker.

Therefore, it would be highly desirable to have a new and improved high resolution display system and method for displaying a large number of different color shading levels utilizing a low cost single panel liquid crystal display device, employing low cost single bit drivers. Moreover, such a system should eliminate, or at least greatly reduce, the loss of color resolution and color information.

Another problem associated with prior known interfaces is known as "contouring." In this regard, because an analog RGB signal is indicative of an infinite number of discrete shading levels, it has been difficult to digitize such an analog signal so that color shade differences in the same primary color sufficiently blend to avoid forming lines of separation when displayed.

A well known technique for eliminating or for at least greatly reducing contouring has been to quantize the supplied analog signal with a sufficient number of digital bits, for example with eight digital bits of data, in order to provide a sufficient number of discrete color shading levels to avoid contouring.

While such a technique provides a sufficient number of discrete color shading levels, such a technique has not proven satisfactory for active matrix display panel units which employ only single bit LCD drivers. More particularly, because a sub-pixel element can only be turned on or off, sophisticated duty cycling techniques have been necessary to obtain only a small number of different shading levels of the same color. Such small numbers, of fifteen or less shading levels, have not been sufficient enough to reduce contouring substantially.

Therefore, it would be highly desirable to have a new and improved high resolution display system and method for displaying a large number of different color levels of the same primary color in order to eliminate or to at least greatly reduce contouring problems associated with low cost active matrix display units employing single bit LCD drivers.

DISCLOSURE OF INVENTION

Therefore, the principal object of the present invention is to provide a new and improved display system and method for producing a large number of shades of color with a fine texture of gradation of high resolution color shading, and with a few number of information bits, such as a single bit of information, for each sub-pixel element of the display system.

Another object of the present invention is to provide such a new and improved system and method, which eliminates or at least reduces greatly the loss of color resolution and color information in displayed images.

A further object of the present invention is to provide such a new and improved method and system, which eliminates or at least reduces greatly contouring in displayed images.

Briefly, the above and further objects of the present invention are realized by providing a method and system, which produces a finely textured display image of a gradation of high resolution color shading. The system accomplishes the high resolution color image with a large number of color shadings, even with only a single bit of information supplied to its display panel for each one of its sub-pixel elements.

The system is adapted to be coupled to a relatively inexpensive high speed active matrix display panel employing single-bit LCD drivers and a plurality of sub-pixel elements. The high resolution display system includes a sub-pixel activation circuit for generating single-bit digital signals for driving individual ones of the sub-pixel elements. A duty cycle circuit arrangement controls the sub-pixel activation circuit to cause desired ones of the sub-pixel elements to be activated selectively an average number of times over a large number of consecutive frame time intervals to generate sub-pixel images having desired perceived color shading levels. A fixed pattern generator responsive to a desired color shading level signal, controls the duty cycle circuit arrangement to activate sub-pixel elements to the desired perceived color shading levels and assigns color codes to groups of sub-pixel elements to produce color blending sub-pixel patterns that help to inhibit substantially color contouring between adjacent sub-pixel element images exhibiting a plurality of different color shading levels of a single primary color.

The high resolution display system also includes a video interface module for coupling either RGB analog signals or RGB digital signals to the high speed LCD display panel.

BRIEF DESCRIPTION OF DRAWINGS

The above mentioned and other objects and features of this invention and the manner of attaining them will become apparent, and the invention itself will be best understood by reference to the following description of the embodiment of the invention in conjunction with the accompanying drawings, wherein:

FIG. 1 is a block diagram of a high color resolution system which is constructed in accordance with the present invention, and which is illustrated being coupled between a video signal producing device and an active matrix display panel;

FIG. 2 is a block diagram of an analog to digital interface arrangement illustrated in FIG. 1;

FIG. 3 is a block diagram of a liquid crystal display controller of FIG. 1;

FIG. 4 is a block diagram of a red sub-pixel arranger of FIG. 3;

FIG. 5 is a block diagram of the pattern logic unit of FIG. 4;

FIG. 6 is a block diagram of the sub-pixel modulator of FIG. 3;

FIG. 6A is a block diagram of a red odd/even sub-pixel logic module of FIG. 5;

FIGS. 7A-E are symbolic representations of sub-pixel patterns mapped into a matrix array corresponding to the matrix array of the active matrix panel of FIG. 1;

FIG. 8 is a symbolic representation of the active matrix panel of FIG. 1, illustrating a plurality of one bit drivers for energizing individual sub-pixel elements in the panel;

FIG. 9 is a symbolic representation of the 2.times.2 pixel array produced by the pattern logic decoder of FIG. 5;

FIG. 10 is a symbolic representation of the color step changes between shading levels of the same primary color as produced by prior known gray scale techniques;

FIG. 11 is a symbolic representation of the color step changes between shading levels of the same color as effected by the apparatus of FIG. 1;

FIG. 12 is a block diagram of the data format unit of FIG. 5;

FIG. 12A is a block diagram of the data format drivers of FIG. 12;

FIG. 12B is a block diagram of the control select register control logic of FIG. 12;

FIG. 12C is a block diagram of a data format arranger of FIG. 6;

FIG. 13 is a symbolic representation energized sub-pixel elements energized to form a concentric circle image on an active matrix panel of FIG. 1;

FIG. 14 is a block diagram of another high color resolution system constructed in accordance with the present invention, and which is illustrated being coupled between a video signal producing device and a passive matrix display panel;

FIG. 15 is a block diagram of an LCD controller of FIG. 14;

FIG. 16 is a block diagram of a sub-pixel modulator of FIG. 15;

FIG. 17 is a block diagram of a red gray scale logic unit of FIG. 16; and

FIG. 18 is a block diagram of a buffered data formatter of FIG. 16.

BEST MODE FOR CARRYING OUT THE INVENTION

The detailed description of the present invention is organized in accordance with the following outline:

A. General System Description (FIG. 1)

B. Active Matrix LCD Panel

C. Interface Unit

D. LCD Controller

D.1. Color Shade Sub-Pixel Arranger

D.1.1 Detailed Description of Color Shade Sub-Pixel Arranger

D.1.2 Pattern Logic

D.1.3 Pattern Logic Equations and Truth Table

D.1.4 Bit Map Memory Controller

D.2. Sub-Pixel Modulator

D.2.1 Detailed Description of the Sub-Pixel Modulator

D.2.2 Sequential Counter with Modifier

D.2.3 ROM translate for Odd and Even

D.2.4 Greater than Comparison

E. Panel Data Formatter

A. General System Description (FIG. 1).

Referring now to the drawings, and more particularly to FIG. 1 thereof, there is shown a high resolution display system 10 which is constructed in accordance to the present invention and which is illustrated coupled between a low cost, high speed display device, such as an active matrix liquid crystal display (LCD) panel 16 and a computer video signal generating source, such as a VGA video drive module 26 driven by a personal computer 21. The high resolution display system 10 responds to a video signal produced by the drive module 26 by transforming the video signal into a plurality of sets of 1-bit digital signals. In this regard, the high resolution display system 10 quantizes and scales the video signal into groups of gray scale coded signals that are mapped into recurring group patterns for each primary color sub-pixel element in order to eliminate or at least reduce substantially contouring between shading levels of the same primary color.

As best seen in FIG. 8, The 1-bit digital signals are arranged in groups of three for driving corresponding sets of sub-pixel elements, such as sub-pixel elements 101A, 101B and 101C, associated with given pixel elements, such as the pixel element 101. Pixel element 101, is one of a plurality of pixel elements arranged in a pixel element matrix array for producing a full color video image via the active matrix panel 16.

The high resolution display system 10 also causes the 1-bit digital signals to be duty cycled at a sufficient rate so that the active matrix panel 16 is able to produce a full color video image having the capability of displaying in excess of ten thousand different color shading level combinations in a substantially flicker free manner.

As best seen in FIG. 1, the high resolution display system 1 generally comprises a video interface controller 13 for coupling the video drive module 26 to the high speed display device 16, and an LCD controller 14 for translating the signals received from the video module 26 into the plurality of sets of 1-bit digital signals.

The video interface controller 13 includes a microprocessor 36 for formatting the video signal produced by the drive module 26 for displaying full color images on the display device 16, and a multiplexing arrangement 15 for converting the signals received from the video module 26 into a plurality of sets of three 5-bit digital signals. Each set of 5-bit digital signals, is indicative of the red, green and blue color codes for one group of sub-pixel elements, such as the sub-pixel elements 101A-C associated with pixel element 101 (FIG. 8).

The LCD controller 14 includes a set of sub-pixel arranger units 43-45 (FIG. 3) that quantize the red, green and blue color code 5-bit digital signals into a corresponding set of 3-bit assigned digital signals for each of the sub-pixel elements, such as th