Compensation for edge effects and cell gap variation in tiled flat-panel, liquid crystal displays

• US 6,184,953 B1
• Filed: 05/26/2000
• Issued: 02/06/2001
• Est. Priority Date: 09/15/1999
• Status: Expired due to Fees

• Current Assignee: TransPacific Exchange, LLC
• Original Assignee: Rainbow Displays, Inc.
• Inventors: Skinner, Dean W., Greene, Raymond G., Yost, Boris, Krusius, J. Peter
• Primary Examiner(s): Dudek, James A.
• Assistant Examiner(s): CHOWDHURY, TARIFUR RASHID
• Application Number:
  US09/579,366
• Time in Patent Office: 256 Days
• Field of Search: 349/74, 349/75, 349/73, 349/187, 345/88, 345/903, 345/199, 348/383
• US Class Current: 349/74
• CPC Class Codes: G02F 1/13336 Combining plural substrates to produce large-area displays, e.g. tiled displays
• CPC Class Codes: G06F 3/147 using display panels
• CPC Class Codes: G09G 2300/026 Video wall, i.e. juxtaposition of a plurality of screens to create a display screen of bigger dimensions
• CPC Class Codes: G09G 2310/0232 Special driving of display border areas
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: G09G 5/393 Arrangements for updating the contents of the bit-mapped memory
• CPC Class Codes: Y10S 345/903 Modular display

Abstract

The present invention features procedures for correcting discoloration and brightness variations due to liquid crystal cell gap variations or other optical, electro-optical, ambient light, electronic, mechanical, and materials anomalies arising in tiled, flat-panel displays. The purpose of these corrections is to achieve a visually seamless appearance. Absolute, relative and/or smoothing corrections are implemented by performing pixel data video processing with correction data acquired from memory. Techniques for determining and applying these corrections are described.

Claims

1. A method for correcting luminance and chromaticity variations caused by optical aberrations near an edge of a tile in tiled, flat-panel liquid crystal displays (LCDs), the steps comprising:

a) identifying an optical aberration affecting sub-pixels proximate an edge of an LCD tile, each of said sub-pixels having an effective T-V curve associated therewith;

b) determining a transfer function for said affected sub-pixels to change one of said effective T-V curves to a predetermined, reference effective T-V curve; and

c) applying an inverse of said transfer function to said affected sub-pixels so that each pixel appears to have substantially said predetermined, reference effective T-V curve.

2. The method for correcting luminance and chromaticity variations in tiled, flat-panel LCDs as recited in claim 1, wherein said inverse transfer function comprises a look-up table.

3. The method for correcting luminance and chromaticity variations in tiled, flat-panel LCDs as recited in claim 2, wherein said look-up table comprises at least one of the group of slope data and offset data.

4. The method for correcting luminance and chromaticity variations in tiled, flat-panel LCDs as recited in claim 3, the steps further comprising:

(d) producing a contour map.

5. A method for correcting luminance and chromaticity variations in tiled, flat-panel LCDs as recited in claim 4, wherein said contour map represents regions of sub-pixels each having a substantially identical effective T-V curve.

6. A method for correcting luminance and chromaticity variations in tiled, flat-panel LCDs as recited in claim 5, wherein said producing a contour map step (d) comprises the sub-steps of:

i) measuring variations of at least one of chromaticity and luminance caused by optical aberrations at a plurality of locations in said LCD tile; and

ii) determining effective T-V curves representative of sub-pixels at said plurality of locations.

7. A method for correcting luminance and chromaticity variations in tiled, flat-panel LCDs as recited in claim 5, wherein said pixels comprise sub-pixels, each transmitting a predetermined, primary color.

8. A method for correcting luminance and chromaticity variations in tiled, flat-panel LCDs as recited in claim 7, wherein said determining transfer function step (b) comprises determining a transfer function for sub-pixels for a mapped region dependent upon said primary color thereof.

9. A method for correcting luminance and chromaticity variations in tiled, flat-panel liquid crystal displays (LCDs) as recited in claim 8, said transfer function is selectively applied to said sub-pixels dependent upon said primary colors thereof.