System and method for superframe dithering in a liquid crystal display

• US 6,801,213 B2
• Filed: 02/21/2001
• Issued: 10/05/2004
• Est. Priority Date: 04/14/2000
• Status: Active Grant

• Current Assignee: Compound Photonics Limited
• Original Assignee: Brillian Corporation (Syntax-Brillian Corporation)
• Inventors: Xu, Gang, Bergstrom, Neil, Huston, Dick
• Primary Examiner(s): Tung, Kee M.
• Assistant Examiner(s): Tran, Tam
• Application Number:
  US09/792,041
• Publication Number:
  US 20020000994A1
• Time in Patent Office: 1,322 Days
• Field of Search: 345/591, 345/593, 345/596, 345/597, 345/600, 345/88, 345/102
• US Class Current: 345/596
• CPC Class Codes: G09G 2300/0804 Sub-multiplexed active matrix panel, i.e. wherein one active driving circuit is used at pixel level for multiple image producing elements
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0814 used for selection purposes, e.g. logical AND for partial update
• CPC Class Codes: G09G 2300/0857 Static memory circuit, e.g. flip-flop
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 2340/0407 Resolution change, inclusive of the use of different resolutions for different screen areas
• CPC Class Codes: G09G 2340/0428 Gradation resolution change
• CPC Class Codes: G09G 2360/18 Use of a frame buffer in a display terminal, inclusive of the display panel
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/2033 with splitting one or more sub-frames corresponding to the most significant bits into two or more sub-frames
• CPC Class Codes: G09G 3/2062 using error diffusion in time
• CPC Class Codes: G09G 3/2092 Details of a display terminals using a flat panel, the details relating to the control arrangement of the display terminal and to the interfaces thereto suitable for both CRT and flat panel G09G5/003; specific for a CRT G09G1/165
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 5/346 for systems having a bit-mapped display memory

Abstract

A system and method are provided for driving a digital display adapted to depict a first number of bits per color field during each frame. In use, a second number of bits is displayed which is greater than the first number of bits. This is accomplished by alternating the display of the bits between frames. To this end, additional bits of color are displayed without increasing the number of bits per color field during each frame.

Claims

1. An image generation system, comprising:

(a) a plurality of display elements, each display element including a pixel;

(b) a plurality of circuits each electrically coupled to a display element;

(c) a plurality of memory cells associated with each of the circuits and a selector for outputting to the display element from one memory cell at a time;

(d) an illumination source for illuminating one or more pixels in a particular color;

(e) a light emitting mechanism and a light modulating mechanism coupled with each of the one or more pixels; and

(f) logic for generating a plurality of sequential frames for displaying N+M bits of color, wherein each of the plurality of sequential frames is generated with only N bits of color such that there are M bits of color difference spatially distributed over M pixel groups of the plurality of sequential frames without increasing the number of bits per color field during each frame.

2. An image generation system as recited in claim 1 wherein additional color are applied in a spatially distributed manner to reduce the amount of brightness modulation that is observed.

3. An image generation system as recited in claim 1, wherein an additional color bit is calculated based on the value of the preceding bit being added to every other frame.

4. The image generation system as recited in claim 1, wherein the digital display is an active matrix panel display.

5. A method for driving a digital display, comprising the steps of:

(a) providing a digital display adapted to display a first number of bits per color field during each frame; and

(b) displaying a second number of bits greater than the first number of bits by spatially distributing in each frame a difference of the second number of bits so that an average of the frames represents a combination of the first and second number of bits;

(c) wherein the first and second number of bits of color are displayed without increasing the number of bits per color field during each frame.

6. A method as recited in claim 5, wherein N+M bits of color are displayed using N digital bits per color field.

7. A method as recited in claim 6, wherein additional color are applied in a spatially distributed manner to reduce the amount of brightness modulation that is observed.

8. A method as recited in claim 6, wherein an additional color bit is calculated based on the value of the preceding bit being added to every other frame.

9. A method as recited in claim 6, wherein a given frame is not displayed which results in a reduction of a perceived intensity modulation and flicker reduction.

10. The method as recited in claim 5, wherein the digital display is an active matrix panel display.