Color Display and Solar Cell Device

• US 20050117096A1
• Filed: 11/17/2004
• Published: 06/02/2005
• Est. Priority Date: 12/02/2003
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Yu, Huinan J., Voloschenko, Dmitry, Li, Zili
• Granted Patent: US 7,339,636 B2
• Time in Patent Office: Days
• US Class Current: 349/114
• CPC Class Codes: G02F 1/13312 Circuits comprising photodetectors for purposes other than feedback
• CPC Class Codes: G02F 1/13318 Circuits comprising a photodetector
• CPC Class Codes: G02F 1/13324 Circuits comprising solar cells
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/1336 Illuminating devices
• CPC Class Codes: G02F 1/133626 providing two modes of illumination, e.g. day-night
• CPC Class Codes: G02F 2201/58 Arrangements comprising a monitoring photodetector
• CPC Class Codes: G02F 2203/055 wavelength filtering
• CPC Class Codes: G02F 2203/62 Switchable arrangements whereby the element being usually not switchable
• CPC Class Codes: G09G 2300/0456 with a reflective area and a transmissive area combined in one pixel, such as in transflectance pixels
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2330/023 using energy recovery or conservation
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers

Abstract

A color display and solar cell device (100, 300, 500), and methods for fabricating and operating the device. The device (100, 300, 500) includes a transparent light source (140, 340, 540) located behind a liquid crystal display (105, 305, 505) that includes a switchable transflector layer (145, 345, 545). In a first embodiment, the liquid crystal display (105) also includes a tri-color pixelized filter (115), the switchable transflector (145) is a switchable broadband transflector, and the transparent light source (140) is a white light source. In a second embodiment, the switchable transflector layer (345) is a tri-color selectable transflector and the transparent light source (340) is a tri-color selectable light source. In a third embodiment, the switchable transflector layer is a switchable broadband transflector and the transparent light source is a tri-color selectable light source. In a fourth embodiment, the switchable transflector layer (545) is a switchable pixelized tri-color transflector and the transparent light source (540) is a tri-color selectable light source.

Claims

1. A color display and solar cell device, comprising:

a liquid crystal display, comprising

a front plate,

a back plate,

a liquid crystal material between the front and back plates, and

a switchable transflector layer located behind the liquid crystal material;

a transparent light source behind the liquid crystal display; and

a solar cell behind the transparent light source that converts a portion of ambient light energy that is incident on the liquid crystal display into electrical energy.

2. The color display and solar cell device according to claim 1, wherein the transparent light source transmits at least 20% of incident light on the front of the transparent light source.

3. The color display and solar cell device according to claim 1, wherein the transparent light source comprises a light pipe that guides light from one or more light emitters to the liquid crystal display.

4. The color display and solar cell device according to claim 1, wherein the transparent light source comprises organic light emitting diodes.

5. The color display and solar cell device according to claim 1, wherein the liquid crystal material is one of a twisted nematic and a super twisted nematic liquid crystal material.

6. The color display and solar cell device according to claim 1, further comprising a controller coupled to the switchable transflector layer, wherein the controller sets the switchable transflector layer to a transmissive state when the liquid crystal display is off.

7. The color display and solar cell device according to claim 6, wherein the controller is further coupled to the liquid crystal material and the controller sets pixels of the liquid crystal material that are in other than a most transmissive back directed polarization state during a reflective duty cycle to the most transmissive back directed polarization state when the liquid crystal display is off.

8. The color display and solar cell device according to claim 1, further comprising a controller coupled to the switchable transflector layer, wherein the controller switches the switchable transflector layer between a reflective state and a transmissive state at least 25 times per second when the liquid crystal display is on.

9. The color display and solar cell device according to claim 8, wherein the controller is further coupled to the liquid crystal material and the controller sets pixels of the liquid crystal material that are in other than a most transmissive polarization state during a reflective duty cycle to the most transmissive polarization state during the transmissive state.

10. The color display and solar cell device according to claim 8, further comprising a photosensor coupled to the controller, wherein the controller switches the switchable transflector layer between the reflective state and the transmissive state with a transmissive state duty cycle that is increased in response to increased ambient light intensity sensed by the photosensor when the ambient light intensity is within a predetermined range.

11. The color display and solar cell device according to claim 10, wherein the controller sets the switchable transflector layer to the transmissive state when the ambient light intensity is below the predetermined range.

12. The color display and solar cell device according to claim 8, further comprising a tri-color pixelized filter that is arranged in front of the switchable transflector layer, wherein the switchable transflector layer is a switchable broadband transflector and the transparent light source is a white light source, and wherein the controller provides color pixel information to the liquid crystal display when the color display and solar cell device is operated in a reflective mode.

13. The color display and solar cell device according to claim 1, further comprising a controller coupled to the switchable transflector layer and to the transparent light source, wherein the switchable transflector layer is a tri-color selectable transflector and the transparent light source is a tri-color selectable light source, and wherein the controller sequentially provides monochrome sub-frames of color information to the liquid crystal display when the liquid crystal display is on.

14. The color display and solar cell device according to claim 13, wherein the controller synchronously selects corresponding reflective states for the switchable transflector layer at a frame rate of at least 25 per second when the color display and solar cell device is operated in a reflective mode and synchronously selects corresponding colors for the transparent light source at a frame rate of at least 25 per second when the color display and solar cell device is operated in a transmissive mode.

15. The color display and solar cell device according to claim 1, further comprising a controller coupled to the switchable transflector layer and to the transparent light source, wherein the switchable transflector layer is a switchable broadband transflector and the transparent light source is a tri-color selectable light source, and wherein the controller provides gray scale frames of information to the liquid crystal display when the color display and solar cell device is operated in a reflective mode and sequentially provides monochrome sub-frames of color information to the liquid crystal display and synchronously selects corresponding reflective states for the switchable transflector layer at a frame rate of at least 25 per second when the color display and solar cell device is operated in a transmissive mode.

16. The color display and solar cell device according to claim 1, further comprising a controller coupled to the switchable transflector layer and to the transparent light source, wherein the switchable transflector layer is a switchable pixelized tri-color transflector and the transparent light source is a tri-color selectable light source, and wherein the controller provides color pixel information to the liquid crystal display when the liquid crystal display is on and the switchable transflector is in one of a reflective and transmissive state.

17. An apparatus that comprises the color display and solar cell device according to claim 1 and a controller coupled to the switchable transflector.

18. A method of fabricating a color display and solar cell device, comprising:

disposing a transparent light source behind a liquid crystal display that comprises a front plate, a back plate, a liquid crystal material between the front and back plates,

disposing a switchable transflector layer behind the liquid crystal material; and

disposing a solar cell behind the transparent light source, wherein the solar cell converts a portion of ambient light energy that is incident on the liquid crystal display into electrical energy.

19. A method of operating a display and solar cell device that comprises a transparent light source located behind a liquid crystal display comprising a switchable transflector layer, the method comprising setting the switchable transflector layer to a transmissive state when the liquid crystal display is off.

20. The method of operating the color display and solar cell device according to claim 19, further comprising switching the switchable transflector layer between a reflective state and a transmissive state at least 25 times per second when the liquid crystal display is on.

21. The method of operating the color display and solar cell device according to claim 20, further comprising switching the switchable transflector layer between the reflective state and the transmissive state with a transmissive state duty cycle that is increased in response to increased ambient light intensity sensed by the photosensor when the ambient light intensity is within a predetermined range.

22. The method of operating the color display and solar cell device according to claim 19, wherein the liquid crystal display further comprises a tri-color pixelized filter that is arranged in front of the switchable transflector layer, and wherein the switchable transflector layer is a switchable broadband transflector, and wherein the transparent light source is a white light source, further comprising providing color pixel information to the liquid crystal display when the color display and solar cell device is operated in a reflective mode.

23. The method of operating the color display and solar cell device according to claim 19, wherein the switchable transflector layer is a tri-color selectable transflector and wherein the transparent light source is a tri-color selectable light source, further comprising sequentially providing monochrome sub-frames of color information to the liquid crystal display when the liquid crystal display is on.

24. The method of operating the color display and solar cell device according to claim 23, further comprising:

synchronously selecting corresponding reflective states for the switchable transflector layer at a frame rate of at least 25 per second when the color display and solar cell device is operated in a reflective mode; and

synchronously selecting corresponding colors for the transparent light source at a frame rate of at least 25 per second when the color display and solar cell device is operated in a transmissive mode.

25. The method for operating a color display and solar cell device according to claim 19, wherein the switchable transflector layer is a switchable broadband transflector and wherein the transparent light source is a tri-color selectable light source, further comprising:

providing gray scale frames of information to the liquid crystal display when the color display and solar cell device is operated in a reflective mode; and

sequentially providing monochrome sub-frames of color information to the liquid crystal display and synchronously selecting corresponding reflective states for the switchable transflector layer at a frame rate of at least 25 per second when the color display and solar cell device is operated in a transmissive mode.

26. The method of operating a color display and solar cell device according to claim 19, wherein the switchable transflector layer is a switchable pixelized tri-color transflector and the transparent light source is a tri-color selectable light source, further comprising providing color pixel information to the liquid crystal display when the liquid crystal display is on and the switchable transflector is in one of a reflective and transmissive state.

27. A method for fabricating a color display and solar cell device, comprising:

fabricating a liquid crystal display, comprising

disposing liquid crystal material between a front and a back plate, and

disposing a switchable transflector layer behind the liquid crystal material;

disposing a transparent light source behind the liquid crystal display; and

disposing a solar cell behind the transparent light source that converts a portion of ambient light energy that is incident on the liquid crystal display into electrical energy.

28. An electronic device, comprising:

a color display and solar cell device, comprising;

a liquid crystal display, comprising

a front plate,

a back plate,

a liquid crystal material between the front and back plates, and

a switchable transflector layer located behind the liquid crystal material;

a transparent light source behind the liquid crystal display; and

a solar cell behind the transparent light source that converts a portion of ambient light energy that is incident on the liquid crystal display into electrical energy; and

battery that is charged by the electrical energy.