Combined temperature and color-temperature control and compensation method for microdisplay systems

• US 7,271,790 B2
• Filed: 10/09/2003
• Issued: 09/18/2007
• Est. Priority Date: 10/11/2002
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: eLCOS Microdisplay Technology, Inc.
• Inventors: Hudson, Edwin Lyle, McDonald, David Charles
• Primary Examiner(s): Awad; Amr A.
• Assistant Examiner(s): Sheng; Tom V
• Application Number:
  US10/682,498
• Publication Number:
  US 20040070562A1
• Time in Patent Office: 1,440 Days
• Field of Search: 345/101, 345/88, 345/87
• US Class Current: 345/88
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers
• CPC Class Codes: G09G 5/02 characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607

Abstract

A temperature control and compensation system is implemented by employing a closely coupled electrical architecture that applies the measured microdisplay temperature, one for each color channel, together with lookup tables preloaded with measured or predicted data for a display, to modify the liquid crystal voltage operating range of each microdisplay as required to achieve and maintain the proper white point operating point for the display. The electrical architecture includes functional blocks as required for realizing the temperature compensation and control for each color channel. The system microprocessor and control unit employs a lookup table to set the control registers on each microdisplay controller with values according to a computed value using the data retrieved from the lookup tables. The range of values in the lookup table includes setups for a number of varied conditions. One of these conditions is temperature.

Claims

1. A liquid crystal display (LCD) system implemented with a thermal control and management system comprising:

a temperature sensor system disposed directly on a backplane of a silicon die of a LCD microdisplay device immediately next to a liquid crystal material for directly measuring a temperature of said microdisplay device and generating a temperature measurement signal;

a microdisplay controller for controlling voltages of said microdisplay device and receiving said temperature signal for transmitting a digital signal to a system processor; and

said system processor having a color-specific-thermal-effect voltage database for receiving and processing said temperature measurement signal by employing said color-specific thermal-effect voltage database to generate color specific temperature-dependent reference voltages to apply as switchable DC-balancing reference voltages to a common electrode connected to a plurality of pixel cells for operating said microdisplay system by accounting for a thermal-effect of color balance whereby said color specific temperature dependent reference voltages are most suitable for said temperature measurement signal and also for said DC-balancing reference voltages.

2. The LCD system of claim 1 wherein:

said system processor further generating a color-specific temperature-dependent black state voltage and a white state voltage as said switchable DC-balancing black state and white state voltages applied to a common electrode connected to a plurality of pixel cells for each color most suitable for said temperature measurement signal accounted for said thermal-effect of color balance.

3. The LCD system of claim 1 wherein:

said microdisplay controller further includes control register for loading and reading said temperature measurement signal as a digital word.

4. The LCD system of claim 1 wherein:

said microdisplay controller further includes color-specific digital-to-analog converter (DAC) output circuits for outputting said color-specific temperature dependent reference voltages to apply as switchable color-specific DC-balancing reference voltages.

5. The LCD system of claim 4 wherein:

said DAC further comprising a resistor digital to analog converter (RDAC).

6. The LCD system of claim 1 wherein:

said system processor further interpolating between two data in said color-specific-thermal-effect voltage database for generating said color-specific temperature dependent reference voltages to apply as switchable color-specific DC-balancing reference voltages.

7. The LCD system of claim 1 wherein:

said temperature sensor system further integrated as an integrated circuit chip disposed directly on a backplane of said silicon die of said LCD microdisplay device.

8. The LCD system of claim 1 wherein:

said temperature sensor system further comprising a PTAT temperature senor system and integrated as an IC chip disposed directly on a backplane of said silicon die of said LCD microdisplay device.

9. The LCD system of claim 1 wherein:

said system processor further includes an additional cooling activating system to activate additional cooling for said LCD microdisplay device in response to said temperature measurement signal.

10. The LCD system of claim 1 wherein:

said system processor further determining if said temperature measurement signal is within a predefined range.

11. The LCD system of claim 1 wherein:

said system processor further receiving and processing said temperature measurement signal to function as a part of a Peltier thermal control loop.

12. The LCD system of claim 1 wherein:

said microdisplay controller generating said color-specific temperature-dependent reference voltages to apply as said switchable DC-balancing reference voltages most suitable for said temperature measurement signal for operating said microdisplay system as a liquid crystal display (LCD) device of a normally white mode accounted for said thermal-effect of color balance.

13. The LCD system of claim 1 wherein:

said microdisplay controller generating said color-specific temperature-dependent reference voltages to apply as said switchable DC-balancing reference voltages most suitable for said temperature measurement signal for operating said microdisplay system as a liquid crystal display (LCD) device of a normally black mode accounted for said thermal-effect of color balance.

14. A liquid crystal display (LCD) system comprising:

a thermal control and management system having a color-specific-thermal-effect voltage database for receiving and processing a microdisplay temperature measurement signal for said microdisplay system by employing said color-specific-thermal-effect voltage database to generate color specific temperature-dependent reference voltages to apply as switchable color-specific DC-balancing voltages for inputting to a multiplexer of a microdisplay controller for controlling a high and a low voltages for a common electrode connected to a plurality of pixel cells of said LCD system switchable for a DC balancing of said LCD display system.

15. The liquid crystal display (LCD) system of claim 14 further comprising:

a system processor for generating a color-specific temperature-dependent black state voltage and a white state voltage as switchable color-specific DC-balancing black state and white state voltages for operating said microdisplay system most suitable for said temperature measurement signal accounted for said thermal effect of color balance.

16. The liquid crystal display (LCD) system of claim 15 further comprising:

a microdisplay controller having a control register for loading and reading said temperature measurement signal.

17. The liquid crystal display (LCD) system of claim 15 wherein:

said system processor further includes DAC output circuits for outputting said temperature dependent reference voltages.

18. The liquid crystal display (LCD) system of claim 15 wherein:

said system processor further interpolating between two data in said database for generating said temperature dependent reference voltages.

19. The liquid crystal display (LCD) system of claim 14 wherein:

said thermal management and control system further includes a temperature sensor system integrated as an integrated circuit chip disposed directly on a backplane of a silicon die of a LCD microdisplay device immediately next to a liquid crystal material in said LCD system.

20. A method for temperature control and compensation for a microdisplay system comprising:

receiving and processing a microdisplay temperature measurement signal from said microdisplay system by employing a color-specific-thermal-effect voltage database to generate color specific temperature-dependent reference voltages; and

applying said color-specific temperature-dependent reference voltage to a multiplexer as switchable color-specific DC-balancing reference voltages for controlling voltages for a common electrode connected to a plurality of pixel cells of said LCD system of said microdisplay system in response to said temperature measurement signal whereby a thermal-effect of color balance is accounted for by said thermal control and management system.

21. The method of claim 20 further comprising:

said step of generating said color specific temperature-dependent reference voltages further comprising a step of multiplexing and generating a color specific temperature-dependent black state voltage and a white state voltage to apply as said switchable color-specific DC-balancing reference voltages to said common electrode connected to said plurality of pixel cells of said LCD system for operating said microdisplay system most suitable for said temperature measurement signal accounted for said thermal effect of color balance.

22. The method of claim 20 wherein:

said step of receiving and processing said temperature measurement signal from said microdisplay system further includes a step of receiving said temperature measurement signal into a system processor having a control register for loading and reading said temperature measurement signal.

23. The method of claim 20 wherein:

said step of generating said color-specific temperature-dependent reference voltages for operating said microdisplay system further comprising a step of outputting said color specific temperature-dependent reference voltages through DAC output circuits.

24. The method of claim 20 wherein:

said step employing said color-specific-thermal-effect voltage database for generating said color specific temperature-dependent reference voltages further comprising a step of interpolating between two data in said color-specific-thermal-effect voltage database for generating said switchable color-specific DC-balancing reference voltages.

25. The method of claim 20 further comprising:

integrating a temperature sensor system as an IC chip disposed directly on a backplane of a silicon die immediately next to a liquid crystal material of said microdisplay system.

26. The method of claim 20 wherein:

said step employing said color-specific-thermal-effect voltage database for generating said color specific temperature-dependent reference voltages further comprising a step of applying a curve-fitting algorithm using data in said color-specific-thermal-effect voltage database for generating said switchable color-specific DC-balancing reference voltages to said common electrode connected to said plurality of pixel cells of said LCD system.

27. A method for controlling and compensating temperature effects of a microdisplay system comprising:

measuring a microdisplay temperature, one for each color channel; and

preloading lookup tables having measured/predicted data for a display, to modify a liquid crystal voltage operating range by generating and applying, for each temperature measurement two switchable color-specific DC-balancing voltages to a common electrode connected to a plurality of pixel cells of said LCD system of said microdisplay for each color as required to achieve and maintain a proper white point operating point for said microdisplay.