Color display and solar cell device
View Patent ↗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.
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. 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.
19. 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.
20. 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.