Methods and devices for lighting displays

• US 7,750,886 B2
• Filed: 07/22/2005
• Issued: 07/06/2010
• Est. Priority Date: 09/27/2004
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Sampsell, Jeffrey B.
• Primary Examiner(s): Hjerpe; Richard
• Assistant Examiner(s): Edwards; Carolyn R
• Application Number:
  US11/187,784
• Publication Number:
  US 20060066783A1
• Time in Patent Office: 1,810 Days
• Field of Search: 345/102, 345/204, 455/566
• US Class Current: 345/102
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02F 1/133342 for double-sided displays
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: G02F 1/133616 Front illuminating devices
• CPC Class Codes: H04M 1/0266 for a display module assembly
• CPC Class Codes: H04M 1/22 Illumination; Arrangements for improving the visibility of characters on dials

Abstract

Various devices and methods of lighting a display are disclosed. In one embodiment, for example, a display device includes a transmissive display configured to be illuminated through a back surface and a reflective display configured to be illuminated through a front surface. A light source is disposed with respect to the back of the transmissive display to illuminate the transmissive display through the back surface. A light pipe is disposed with respect to the light source to receive light from the light source and is configured to propagate the light such that this light provides front illumination of the reflective display.

Claims

1. A display device comprising:

a transmissive display comprising a front surface and a back surface, the transmissive display configured to be illuminated through the back surface;

a reflective display comprising a front surface and a back surface, said reflective display configured to be illuminated through the front surface, the back surface of the reflective display disposed toward the back surface of the transmissive display;

a light source disposed between the back of the transmissive display and the back of the reflective display, the light source configured to illuminate the transmissive display through the back surface; and

a light pipe disposed with respect to the light source to receive light therefrom, said light pipe configured to propagate said light such that said light provides front illumination of said reflective display.

2. The device of claim 1, wherein the transmissive display comprises a transreflective display.

3. The device of claim 2, wherein the transreflective display comprises a liquid crystal display.

4. The device of claim 1, wherein said reflective display comprises an interferometric display.

5. The device of claim 4, wherein said interferometric display comprises a plurality of interferometric modulator devices.

6. The device of claim 1, wherein the light pipe comprises a substantially annularly shaped exit port.

7. The device of claim 1, wherein the light pipe comprises an exit port disposed to transfer light to a portion of a front edge of the reflective display.

8. The device of claim 7, wherein the exit port of the light pipe has a numerical aperture that substantially matches the numerical aperture of the front edge portion of the reflective display such that etendue is substantially conserved between the exit port and the front edge portion.

9. The device of claim 7, wherein said reflective display comprises a substrate and said exit port of the light pipe is configured to transfer light to said substrate.

10. The device of claim 8, wherein the exit port is optically coupled through air to the front edge portion of the reflective display.

11. The device of claim 8, wherein the exit port is optically coupled through index matching material to the front edge portion of the reflective display.

12. The device of claim 11, wherein the index matching material comprises index matching cement.

13. The device of claim 9, wherein the exit port of the light pipe has a numerical aperture that substantially matches the numerical aperture of the front edge portion of the reflective display such that etendue is substantially conserved between the exit port and the front edge portion.

14. The device of claim 1, wherein the light pipe is hollow.

15. The device of claim 1, further comprising a substantially optically transmissive component disposed forward of the reflective display and optically coupled to an exit port of the light pipe.

16. The device of claim 15, wherein said substantially optically transmissive component comprises a plate, sheet, film, or layer.

17. The device of claim 16, wherein said plate, sheet, film, or layer is laminated on the front surface of the reflective display.

18. The device of claim 15, wherein said substantially optically transmissive component comprises one or more optical structures that direct at least a portion of the light entering the substantially optically transmissive component to the reflective display.

19. The device of claim 18, wherein the one or more optical structures are configured to substantially evenly disperse the light transferred from the light pipe across the reflective display.

20. The device of claim 15, wherein the exit port is optically coupled through air to the substantially optically transmissive component.

21. The device of claim 15, wherein the exit port is optically coupled through index matching material to the substantially optically transmissive component.

22. The device of claim 21, wherein the index matching material comprises index matching cement.

23. The device of claim 15, wherein the exit port of the light pipe is configured such that etendue is substantially conserved between the exit port and the substantially optically transmissive component.

24. The device of claim 15, wherein the substantially optically transmissive component comprises a light guide.

25. The device of claim 15, wherein said substantially optically transmissive component comprises an optical plate.

26. The device of claim 1, wherein the light pipe comprises relatively high index material for propagating light via total internal reflection.

27. The device of claim 26, wherein the relatively high index material comprises plastic or glass.

28. The device of claim 1, wherein the light pipe is coated with reflective material to substantially confine light therein during propagation therethrough.

29. The device of claim 1, wherein the light pipe comprises a backplate for said reflective display.

30. The device of claim 1, further comprising:

a processor that is in electrical communication with at least one of said transmissive display and said reflective display, said processor being configured to process image data; and

a memory device in electrical communication with said processor.

31. The device of claim 30, further comprising:

a first controller configured to send at least one signal to at least one of said transmissive or reflective displays; and

a second controller configured to send at least a portion of said image data to said first controller.

32. The device of claim 31, further comprising an image source module configured to send said image data to said processor.

33. The device of claim 32, wherein said image source module comprises at least one of a receiver, transceiver, and transmitter.

34. The device of claim 30, further comprising an input device configured to receive input data and to communicate said input data to said processor.

35. A method of illuminating a reflective display and a transmissive display with a light source, the reflective and transmissive displays being positioned in a back-to-back configuration, the method comprising:

disposing the light source between the back of the transmissive display and the back of the reflective display, the light source configured to illuminate the transmissive display through the back of the transmissive display;

disposing a light pipe with respect to the light source to receive light therefrom; and

disposing the light pipe with respect to the reflective display such that light exiting the light pipe provides front illumination for the reflective display.

36. A display device manufactured by the method of claim 35.

37. A display device, comprising:

a first reflective display comprising a viewable surface and a back surface;

a second reflective display comprising a viewable surface and a back surface, the back surface of the first display disposed substantially facing the back surface of the second display;

a light source; and

light piping optically coupled to the light source and optically coupled to an edge or surface of both the first and second displays, the light piping configured to transfer light emitted from the light source into a portion of the viewable surface of both the first and second displays providing front illumination to the first and second displays.

38. The display device of claim 37, wherein the light piping comprises a backplate for one of the displays.

39. The display device of claim 37, wherein the light piping comprises a backplate for each of the first and second displays.

40. The display device of claim 37, wherein the light piping comprises a single backplate that provides light to both the first and second displays.

41. A display device comprising:

first means for displaying an image, said first means for displaying comprising a front surface and a back surface,

second means for displaying an image comprising a front surface and a back surface, the back surface of said first means for displaying disposed toward the back surface of said second means for displaying;

means for illuminating disposed between the back surface of the first displaying means and the back surface of the second displaying means, said illuminating means configured to provide light to said first displaying back surface; and

light guiding means configured to receive light from said illuminating means and configured to propagate said light to said second displaying means to provide front illumination to said second displaying means;

wherein said means for illuminating said first means for displaying comprises a light source disposed with respect to the back of said first means for displaying an image to illuminate said first means for displaying an image through the back surface.

42. The device of claim 41, wherein said first means for displaying an image comprises a transmissive display.

43. The device of claim 41, wherein said second means for displaying an image comprises an interferometric display.

44. The device of claim 41, wherein said means for illuminating said second means for displaying comprises a light pipe disposed with respect to said means for illuminating said first means for displaying to receive light therefrom, said light pipe configured to propagate the light such that the light provides front illumination of said second means for displaying an image.

46. The device of claim 43, wherein said interferometric display comprises a plurality of interferometric modulator devices.

45. A method of illuminating a reflective display and a transmissive display with a light source, the reflective and transmissive displays being positioned in a back-to-back configuration, the method comprising:

displaying an image on a transmissive display, said transmissive display comprising a front surface and a back surface,

displaying an image on a reflective display, said reflective display comprising a front surface and a back surface;

illuminating said transmissive display through the back surface using a light source disposed between the back surface of the transmissive display and the back surface of the reflective display; and

illuminating said reflective display through the front surface using said light source.