Thermally compensated pixels for liquid crystal displays (LCDS)

• US 9,035,932 B2
• Filed: 08/31/2012
• Issued: 05/19/2015
• Est. Priority Date: 08/31/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Huang, Yi, Gu, Mingxia, Drolet, Jean-Jacques Philippe, Chen, Wei
• Primary Examiner(s): Cheng, Joe H
• Application Number:
  US13/601,849
• Publication Number:
  US 20140062981A1
• Time in Patent Office: 991 Days
• Field of Search: 345/87, 345/88, 345/92, 345/106, 345/204, 345/211, 349/33
• US Class Current: 345/211
• CPC Class Codes: G02F 1/133382 Heating or cooling of liquid crystal cells other than for activation, e.g. circuits or arrangements for temperature control, stabilisation or uniform distribution over the cell
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2300/043 Compensation electrodes or other additional electrodes in matrix displays related to distortions or compensation signals, e.g. for modifying TFT threshold voltage in column driver
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

Systems, methods, and devices are provided for an electronic display with thermally compensated pixels. Such an electronic display may have an array of pixels, at least some of which may be thermally compensated pixels that exhibit reduced thermal color shift over an operational temperature range. These thermally compensated pixels may have compensation electrodes that induce an electric field in the thermally compensated pixel that cause a reduction in color shift.

Claims

1. A display, comprising:

an array of pixels, wherein at least one pixel in the array of pixels is a thermally compensated pixel, the thermally compensated pixel comprising;

a liquid crystal layer having a first side and a second side, wherein the first side is opposite of the second side;

a pixel electrode disposed on the first side of the liquid crystal layer;

a common electrode disposed on the first side of the liquid crystal layer; and

at least one compensation electrode disposed on the second side of the liquid crystal layer.

2. The display of claim 1, comprising:

a black mask delineating at least one edge of the thermally compensated pixel in the array of pixel; and

a color filter disposed between the liquid crystal layer and the black mask.

3. The display of claim 1, wherein the at least one compensation electrode is configured to be driven with a voltage during operation of the display.

4. The display of claim 3, wherein the at least one compensation electrode is configured to be driven at a constant voltage during operation of the display.

5. The display of claim 3, wherein the at least one compensation electrode is configured to be:

driven with a first voltage when the temperature of the display is lower than a first temperature; and

driven at a second voltage when the temperature of the display is higher than a second temperature, wherein the second temperature is higher than the first temperature.

6. The display of claim 3, wherein the at least one compensation electrode is driven by a variable voltage, wherein the voltage is related to the temperature of the display.

7. The display of claim 1, wherein the thermally compensated pixel comprises a first compensation electrode and a second compensation electrode, wherein the first compensation electrode is disposed generally along a first edge of the thermally compensated pixel and the second compensation electrode is disposed generally along a second edge of the thermally compensated pixel.

8. The display of claim 7, wherein the first and second compensation electrodes are configured to be driven by a voltage, wherein the voltage induces a vertical electric field in the liquid crystal layer, between the first compensation electrode and the pixel electrode and between the second compensation electrode and the pixel electrode.

9. The display of claim 1, wherein the array of pixels includes a red pixel, a green pixel, and a blue pixel, wherein the blue pixel comprises the thermally compensated pixel.

10. An electronic device comprising:

data processing circuitry configured to generate image data signals; and

an electronic display configured to display the image data signals on an array of pixels, the array of pixels comprising at least one thermally compensated pixel, the thermally compensated pixel comprising;

a liquid crystal layer having a first side and a second side, wherein the first side is opposite of the second side;

a pixel electrode disposed on the first side of the liquid crystal layer;

a common electrode disposed on the first side of the liquid crystal layer; and

at least one compensation electrode disposed on the second side of the liquid crystal layer.

11. The electronic device of claim 10, comprising an interface configured to receive an operator input and send an input signal to the data processing circuitry based on the operator input.

12. The electronic device of claim 11, comprising a touch screen portion of the display.

13. The electronic display of claim 10, wherein the at least one compensation electrode is configured to be driven at a voltage during operation of the display.

14. The electronic device of claim 10, wherein the at least one compensation electrode is configured to be:

driven at a first voltage when the temperature of the display is lower than a first temperature; and

driven at a second voltage when the temperature of the display is higher than a second temperature, wherein the second temperature is higher than the first temperature.

15. The electronic device of claim 10, wherein the at least one compensation electrode is driven by a variable voltage, wherein the voltage is related to the temperature of the display.

16. The display of claim 10, wherein the array of pixels includes a red pixel, a green pixel, and a blue pixel, wherein the blue pixel comprises the thermally compensated pixel.

17. A method of correcting a thermal color shift, comprising:

providing a voltage to a plurality of compensation electrodes in respective thermally compensated pixels of an LCD display to compensate for changes in transmittance of the thermally compensated pixels due to temperature variations.

18. The method of claim 17, wherein the step of providing a voltage further comprises:

generating a vertical electric field in the thermally compensated pixels for the compensation.

19. The method of claim 17, wherein the LCD display comprises a plurality of red pixels, a plurality of green pixels, and a plurality blue pixel, wherein at least one of the plurality of blue pixel comprises at least one of the thermally compensated pixels.

20. The method of claim 17, comprising:

providing a constant voltage to the plurality of compensation electrodes during operation of the LCD display.

21. The method of claim 17, comprising:

providing a voltage to the plurality compensation electrodes if the temperature of the LCD display is lower than a first temperature; and

providing a second voltage to the plurality of compensation electrodes if the temperature of the LCD display is higher than a second temperature, wherein the second temperature is higher than the first temperature.

22. The method of claim 17, comprising:

providing a variable voltage to the at least one compensation electrode, wherein the voltage value is inversely related to the temperature of the LCD display.

23. A method of manufacturing a display, comprising:

forming a thin film transistor layer on a lower substrate, wherein the thin film transistor layer comprises a common electrode and a pixel electrode;

disposing a liquid crystal layer on the thin film transistor layer; and

disposing at least one compensation electrode on a side of the liquid crystal layer opposite the thin film transistor layer, wherein the pixel electrode, the at least one compensation electrode, and a portion of the thin film transistor layer and liquid crystal layer correspond to a thermally compensated pixel in an array of pixels.

24. The method of claim 23, comprising:

disposing two compensation electrodes at opposite edges of the thermally compensated pixel.

25. The method of claim 23, comprising:

disposing a black mask on the liquid crystal layer opposite the thin film transistor layer, wherein the black mask further delineates edges of the thermally compensated pixel.

26. A method of manufacturing an electronic device, comprising:

coupling a processing circuit to a display; and

disposing the processing circuit and the display in a housing, wherein the display is made by;

forming a thin film transistor layer on a lower substrate, wherein the thin film transistor layer comprises a common electrode and a pixel electrode;

disposing a liquid crystal layer on the thin film transistor layer; and

disposing at least one compensation electrode on a side of the liquid crystal layer opposite the thin film transistor layer, wherein the pixel electrode, the at least one compensation electrode, and a portion of the thin film transistor layer and liquid crystal layer correspond to a thermally compensated pixel in an array of pixels.

27. The method of manufacturing an electronic device of claim 26, wherein the display is made by:

disposing two compensation electrodes at opposite edges of the thermally compensated pixel.

28. The method of manufacturing an electronic device of claim 26, comprising:

assembling the housing, processing circuitry, and the display, or a subset thereof.