Stacked OLED display having improved efficiency

• US 6,987,355 B2
• Filed: 06/11/2003
• Issued: 01/17/2006
• Est. Priority Date: 06/11/2003
• Status: Active Grant

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: Eastman Kodak Company
• Inventors: Cok, Ronald S.
• Primary Examiner(s): Patel, Nimeshkumar D.
• Assistant Examiner(s): RIELLEY, ELIZABETH A
• Application Number:
  US10/459,685
• Publication Number:
  US 20040251821A1
• Time in Patent Office: 951 Days
• Field of Search: 313/504, 313/503, 313/501, 313/506, 313/509, 313/110, 313/111, 313/112, 428/690, 257/99, 257/98, 257/100
• US Class Current: 313/506
• CPC Class Codes: G09G 2300/0452 Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 3/3208 organic, e.g. using organic light-emitting diodes [OLED]
• CPC Class Codes: G09G 3/3216 using a passive matrix
• CPC Class Codes: G09G 3/3225 using an active matrix
• CPC Class Codes: H10K 50/125 specially adapted for multicolour light emission, e.g. for emitting white light
• CPC Class Codes: H10K 59/351 comprising more than three subpixels, e.g. red-green-blue-white [RGBW]
• CPC Class Codes: H10K 59/38 comprising colour filters or colour changing media [CCM]

Abstract

An OLED device, having a pixel includes a plurality of individually addressable first white light emitting elements; a corresponding plurality of color filters located over the first white light emitting elements to filter the light emitted by the first white light emitting elements; and a second separately addressable white light emitting element located over the color filters for passing the filtered white light and emitting white light.

Claims

1. An OLED device, having a pixel comprising:

a) a plurality of individually addressable first white light emitting elements;

b) a corresponding plurality of color filters located over the first white light emitting elements to filter the light emitted by the first white light emitting elements; and

c) a second separately addressable white light emitting element located over the color filters for passing the filtered white light and emitting white light.

2. The OLED device claimed in claim 1, wherein the colors of the filters are red, green, and blue.

3. The OLED device claimed in claim 2, wherein the green color filter and corresponding first white light emitting element have a larger area than the red or blue color filter and corresponding first white light emitting elements.

4. The OLED device claimed in claim 1, wherein the first white light emitting elements and corresponding color filters are of different sizes.

5. The OLED device claimed in claim 4, wherein the relative sizes of first white light emitting elements and corresponding color filters correspond to the expected color usage of the display, wherein elements and corresponding filters having colors with greater expected usage are larger.

6. The OLED device claimed in claim 1, wherein two or more of the color filters are the same color.

7. The OLED device claimed in claim 6, wherein the two or more color filters are green.

8. The OLED device claimed in claim 1, wherein the total area of the first white light emitting element is different than the area of the second white light emitting element.

9. The OLED device claimed in claim 1, wherein the first and second white light emitting elements are composed of the same light emitting materials.

10. The OLED device claimed in claim 1, wherein the white point of white light elements matches the white point of the display.

11. The OLED device claimed in claim 1 wherein the white point of the white light emitting elements matches the white point of color filters.

12. The OLED device claimed in claim 1, wherein the color filters are absorption filters.

13. The OLED device claimed in claim 1, wherein the color filters are dichroic filters.

14. The OLED device claimed in claim 1, wherein the OLED device is a top emitting device.

15. The OLED device claimed in claim 1, wherein the OLED device is a bottom emitting device.

16. The OLED device claimed in claim 1, wherein the pixel has a square shape and the color filters and first white light emitting elements are arranged in a stripe pattern in the square shape.

17. The OLED device claimed in claim 1, wherein the pixel has a square shape and the color filters and first white light emitting elements are arranged in rectangular array in the square shape.

18. The OLED device claimed in claim 1, wherein the color filters include a clear filter.

19. The OLED device claimed in claim 1, further comprising a controller for converting an RGB color image signal to an RGBW signal.

20. The OLED device claimed in claim 19, wherein the controller determines the minimum (MIN) of the RGB signal and produces the RGBW signal as R=R-MIN, G=G-MIN, B=B-MIN, W=MIN.

21. An OLED device, comprising:

a) a substrate;

b) a first addressable white light emitting element formed on the substrate;

c) a color filter located over the first white light emitting element; and

d) a second separately addressable white light emitting element located over the color filter.

22. The OLED device claimed in claim 21, wherein the OLED device is a top emitting device, and the color filter filters the light from the first white light emitting element.

23. The OLED device claimed in claim 22, further comprising a reflector located between the first white light emitting element and the substrate.

24. The OLED device claimed in claim 23, wherein the reflector comprises an electrode.

25. The OLED device claimed in claim 21, wherein the OLED device is a bottom emitting device, and the color filter filters the light from the second white light emitting element.

26. The OLED device claimed in claim 25, further comprising a reflector located over the second white light emitting element.

27. The OLED device claimed in claim 26, wherein the reflector comprises an electrode.