System and method for providing a wide aspect ratio flat panel display monitor independent white-balance adjustment and gamma correction capabilities

• US 6,611,249 B1
• Filed: 07/22/1998
• Issued: 08/26/2003
• Est. Priority Date: 07/22/1998
• Status: Expired due to Term

• Current Assignee: RPX Corporation
• Original Assignee: Silicon Graphics Incorporated (Graphics Properties Holdings, Inc.)
• Inventors: Evanicky, Daniel E., Medina, Oscar Ivan
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): Nguyen, Kevin M.
• Application Number:
  US09/120,960
• Time in Patent Office: 1,861 Days
• Field of Search: 345/150, 345/153, 345/154, 345/207, 345/88, 345/102, 345/600, 345/589, 345/89
• US Class Current: 345/102
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0291 Housings; Spectrometer accessories; Spatial arrangement of elements, e.g. folded path arrangements
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/0061 to provide homogeneous light output intensity
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02F 1/133609 including means for improving the color mixing, e.g. white
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/0606 Manual adjustment
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2320/0673 for control of gamma adjustment, e.g. selecting another gamma curve
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 2340/06 Colour space transformation
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 2370/04 Exchange of auxiliary data, i.e. other than image data, between monitor and graphics controller
• 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 3/2018 by time modulation using two or more time intervals
• 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 3/3413 : Details of control of colour illumination sources
• CPC Class Codes: G09G 3/3611 : Control of matrices with row and column drivers
• CPC Class Codes: G09G 5/006 : Details of the interface to the display terminal specific for a display terminal using a CRT G09G1/167; using a flat panel G09G3/2096; circuits for interfacing with colour displays G09G5/04
• CPC Class Codes: G09G 5/06 : using colour palettes, e.g. look-up tables
• CPC Class Codes: H04N 17/045 : Self-contained testing apparatus
• CPC Class Codes: H04N 5/66 : Transforming electric information into light information scanning details H04N3/00
• CPC Class Codes: H04N 9/73 : Colour balance circuits, e.g. white balance circuits or colour temperature control camera processing pipelines for colour balance H04N23/88
• CPC Class Codes: Y10S 345/904 : Display with fail/safe testing feature

Abstract

A system and method are described herein for controlling the white balance and providing gamma correction without compromising gray-scale dynamic range in a flat panel liquid crystal display (LCD). According to one embodiment of the present invention, the flat panel LCD includes electronic circuitry for coupling to a host computer to receive a white-balance adjustment control signal, and electronic circuitry for receiving image data to be rendered on the flat panel LCD. Further, the flat panel LCD of one embodiment is configured for coupling to a color-sensing device to receive optical characteristics data of the flat panel LCD detected by the color-sensing device. The white balance adjustment mechanisms include the provision of two or more light sources of differing color temperature, whose brightness can be independently varied (and distributed through a light distribution mechanism) to adjust color temperature without altering the grayscale resolution of the RGB colors. The present invention further includes white balance adjustment software and gamma correction software for generating white-balance adjustment control signals and appropriate gamma correction curves.

Claims

1. A high-precision flat panel monitor for displaying information originated by a host computer, said precision flat panel monitor comprising:

an image data input for coupling to said host computer to receive image data;

a liquid crystal display screen for displaying a representation of said image data, said liquid crystal display screen further comprising a first white light source of a first color temperature and a second white light source of a second color temperature, wherein said first and second white light sources are positioned to illuminate said liquid crystal display screen with light having a net color temperature that is adjustable by adjusting a first luminance level of said first white light source and a second luminance level of said second white light source;

a white-balance adjustment control input for coupling to said host computer to receive a white-balance adjustment control signal, wherein said white-balance adjustment control signal further comprises a first signal for controlling said first luminance level and a second signal for controlling said second luminance level; and

a controller circuit responsive to said white-balance adjustment control signal for adjusting a white-balance of said liquid crystal display screen, wherein grayscale resolution of said liquid crystal display screen is substantially unaffected by said adjusting of said white-balance of said liquid crystal display screen.

2. The high-precision flat panel monitor according to claim 1 further comprising:

a color measurement input configured for coupling to a colorimeter to receive color measurement data associated with said liquid crystal display screen; and

a color measurement output configured for coupling to said host computer to transmit said color measurement data of said liquid crystal display screen for color-correcting said representation of said image data.

3. The high-precision flat panel monitor according to claim 1 wherein said controller circuit comprises an inter-integrated circuit (I2C) interface for receiving said white-balance adjustment control signal from said host computer.

4. The high-precision flat panel monitor according to claim 1 wherein said image data is transmitted from said host computer to said high-precision flat panel monitor via a digital interface.

5. The high-precision flat panel monitor according to claim 4 wherein said digital interface comprises a low-voltage differential signal (LVDS) interface.

6. The high-precision flat panel monitor according to claim 2 wherein said color measurement output comprises an inter-integrated circuit interface for transmitting said color measurement data from said high-precision flat-panel monitor to said host computer.

7. The high-precision flat panel monitor according to claim 1 wherein said liquid crystal display screen comprises optical compensation films for providing increased off axis angle viewing capability in both the vertical and horizontal directions.

8. The high-precision flat panel monitor according to claim 1 wherein said liquid crystal display screen has a large viewing area and a wide aspect ratio.

9. The high-precision flat panel monitor according to claim 1 wherein said liquid crystal display screen further comprises an in-plane switching liquid crystal layer for improved viewing angle.

10. The high-precision flat panel monitor according to claim 1 wherein said liquid crystal display screen further comprises a liquid crystal layer of anti-ferroelectric material for improved viewing angle.

11. The high-precision flat panel monitor according to claim 1 wherein said liquid crystal display screen further comprises a plurality of pixels having a uniform pixel pitch of approximately 0.23 mm.

12. The high-precision flat panel monitor according to claim 1 further comprising a light pipe optically coupled to receive light from said first white light source and said second white light source, said light pipe for illuminating said liquid crystal display screen with said light from said first white light source and said second white light source.

13. The high-precision flat panel monitor according to claim 12 wherein said light pipe further comprises an extraction pattern designed to uniformly distribute light to said liquid crystal display screen.

14. A high-precision flat panel monitor comprising:

an image data input for coupling to said host computer to receive image data;

a liquid crystal display screen for displaying said image data, said liquid crystal display screen including;

a first white light source of a first color temperature;

a second white light source of a second color temperature different from said first color temperature, said first and second white light sources positioned to illuminate said liquid crystal display screen with light having a net color temperature that is dependent on an intensity of said first white light source and an intensity of said second white light source wherein said first and said second white light sources alter said net color temperature of said light, within a predetermined color temperature range, by controlling said intensity of said first white light source and said intensity of said second white light source; and

a white-balance adjustment control input for coupling to said host computer to receive a white-balance adjustment control signal, said white-balance adjustment control signal for adjusting said intensity of said first white light source and said intensity of said second white light source to adjust said net color temperature of said liquid crystal display screen, wherein grayscale resolution of said liquid crystal display screen is substantially unaffected by adjustment of said net color temperature.

15. A system for color-correcting a high-precision flat panel monitor, said flat panel monitor having a first white light source of a first color temperature and a second white light source of a second color temperature configured for adjusting white-balance of said high-precision flat panel monitor, the system comprising:

a digital computer for coupling to transmit image data to said high-precision flat panel monitor, said digital computer having a memory stored color look-up table (LUT) for translating an uncorrected color value to a corrected color value according to a gamma curve, said digital computer further having a white-balance adjustment control output configured for coupling to said high-precision flat panel monitor to control white-balance by varying intensity levels of said first white light source and said second white light source without substantially affecting a grayscale resolution of the monitor; and

a calorimeter for coupling to said digital computer, said calorimeter for measuring color characteristics data of said high-precision flat panel monitor during a color calibration process and for transmitting said color characteristics data to said digital computer during said color calibration process, wherein said digital computer is for adjusting said gamma curve according to any discrepancies between said color measurement data and a predefined color profile.

16. The system as described in claim 15 wherein said predefined color profile describes color characteristics of a reference display screen such that color characteristics of said high-precision flat panel monitor substantially match color characteristics of said reference display screen.

17. The system as described in claim 15 wherein said digital computer further comprises a communication port for receiving said predefined color profile from a computer network.

18. The system as described in claim 17 wherein said predefined color profile describes color characteristics of a master flat panel monitor such that said high-precision flat panel monitor is calibrated to match said master flat panel monitor, and wherein said master flat panel monitor is remotely coupled to said digital computer via said computer network.

19. The system as described in claim 15 wherein said predefined color profile describes color characteristics of said high-precision flat panel monitor and wherein said predefined color profile is generated at a preceding calibration session.

20. The system as described in claim 15 further comprising electronic circuitry for frame-rate modulating grayscale values stored in said color LUT such that visual artifacts in said high-precision flat panel monitor are substantially reduced.

21. A computer-usable medium having computer-readable program code embodied therein for causing a computer to perform a method of color-calibrating a flat panel display, said flat panel display having a liquid crystal display screen configured to be illuminated by a first white light source with a first color temperature and a second white light source with a second color temperature, said method comprising the steps of:

displaying on said flat panel display an image having a predefined white-balance value;

determining color characteristics of said flat panel display, said color characteristics being provided by a light-sensing device coupled to said flat panel display, said color characteristics further including white-balance data and gamma values of said flat panel display;

comparing said white-balance data to a predetermined reference white-balance value; and

transmitting a white-balance adjustment control signal to said flat panel display to adjust a color temperature of said flat panel display by adjusting a first intensity level of said first light source and a second intensity level of said second light source without substantially affecting a grayscale resolution of the display, wherein white-balance adjustment control signal is generated according to differences between said white-balance data and said predetermined reference white-balance value.

22. The computer-usable medium as described in claim 21 wherein said method further comprises the step of repeating said displaying determining, comparing, and transmitting steps until said white-balance data of said flat panel display approximately matches said predetermined reference white-balance value.

23. The computer-usable medium as described in claim 21 wherein said flat panel display comprises a large area wide aspect ratio liquid crystal display screen.

24. The computer-usable medium as described in claim 23 wherein said large area flat panel display is non-emissive and further comprises:

a first white light source of a first color temperature; and

a second white light source of a second color temperature different from said first color temperature, said first and second white light sources positioned to illuminate said large area flat panel display with light having a net color temperature that is dependent on an intensity of said first white light source and an intensity of said second white light source wherein said first and said second white light sources alter said net color temperature of said light, within a predetermined color temperature range, wherein said intensity of said first white light source and said intensity of said second white light source are controlled by said white-balance adjustment control signal.

25. The computer-usable medium as described in claim 21 wherein said white-balance adjustment control signal and said color characteristics data are transmitted between said computer and said flat panel display via an inter-integrated circuit interface.

26. The computer-usable medium as described in claim 21 wherein said light-sensing device comprises a colorimeter.

27. The computer-usable medium as described in claim 26 wherein said calorimeter further comprises attachment means for attaching to said flat panel display without affecting color characteristics of said flat panel display.

28. The computer-usable medium as described in claim 21 wherein said method further comprises the steps of:

comparing said gamma values of said flat panel display to a predetermined reference gamma curve; and

modifying a color look-up table stored in a memory unit of said computer to alter said gamma values of said flat panel display until said gamma values approximately match said predetermined reference gamma curve.

29. The computer-usable medium as described in claim 28 wherein said method further comprises the step of frame-rate modulating said gamma values such that visual artifacts are substantially reduced.