Harnessing front light in e-readers to generate electricity

Patent metadata

Field	Value
Publication number	US-9837852-B1
Application number	US-201414577160-A
Country	US
Kind code	B1
Filing date	Dec 19, 2014
Priority date	Dec 19, 2014
Publication date	Dec 5, 2017
Grant date	Dec 5, 2017

Abstract

An electronic device with a e-paper display that internally integrates photovoltaic cells and are not apparent from the exterior of the device. A light source of the device injects light into a light guide to front-light the e-paper. Light that leaks from edges of the light guide is captured by the photovoltaic cells. The plastic light guide is also impregnated with a photoluminescent material that absorbs near infrared energy that is incident on a face of the display and re-emits it isotropically to be guided by the light guide to the photovoltaic cells. By combining multiple techniques to illuminate hidden photovoltaic cells, the utility of the hidden cells is maximized.

First claim

What is claimed is:

1. A computing device, comprising:
a front-lit reflective electronic display screen, comprising in order from an exterior surface of the device:
a clear cover layer comprising plastic or glass,
a first light guide composed of plastic including a first photoluminescent material, the first light guide being substantially transparent to visible wavelengths of light, the first photoluminescent material absorbing light incident on the display through the clear cover layer in a first near-infrared wavelength and emitting absorbed energy as light in a longer second near-infrared wavelength, and
a reflective electronic display;

a plurality of light emitting diodes (LEDs) proximate to a first edge of the first light guide, the plurality of LEDs arranged to inject light having visible wavelengths into the first light guide to illuminate the reflective electronic display;
a photovoltaic cell arranged along a second edge of the first light guide, wherein a light absorbing surface of the photovoltaic cell is oriented perpendicular to an exposed face of the display screen, the photovoltaic cell configured to:
receive at least some of the visible wavelengths of the light emitted from the LEDs, via the first light guide, and convert energy of the at least some of the visible wavelengths of the light into electrical power, and
receive the second near-infrared wavelength and covert energy associated with the second near-infrared wavelength into electrical power;

a battery that powers the computing device; and
a battery charge controller configured to charge the battery using the electrical power from the photovoltaic cell.

2. The computing device of claim 1 , wherein the first photoluminescent material comprises an organic dye or quantum dots.

3. The computing device of claim 1 , further comprising:
a bezel around the display composed of a plastic that is substantially opaque to visible wavelengths of light and substantially transparent to a third near-infrared wavelength; and
a second light guide composed of plastic including a second photoluminescent material, the second light guide arranged around the display proximate to the second edge, the photovoltaic cell being arranged between the first and second light guides, the second photoluminescent material absorbing light having the third near-infrared wavelength that passes through the bezel and emitting absorbed energy as light in a longer fourth near-infrared wavelength,
wherein the photovoltaic cell is double-sided and is further configured to:
receive the fourth near-infrared wavelength and convert energy associated with the fourth near-infrared wavelength into electrical power.

4. The computing device of claim 1 , wherein a portion of the clear cover layer extends beyond the second edge of the first light guide, the computing device further comprising:
a reflector with a light diffusing surface arranged between the photovoltaic cell and the reflective electronic display, the reflector configured to reflect incident light received through the portion of the clear cover layer toward the photovoltaic cell.

5. A device comprising:
a display screen comprising in order from an exterior surface of the device:
a clear cover layer,
a first light guide substantially transparent to visible wavelengths of light, and
a reflective electronic display;

a light source proximate to a first edge of the first light guide, the light source arranged to inject light having visible wavelengths into the first light guide to illuminate the reflective electronic display; and
a photovoltaic cell arranged along a second edge the first light guide, wherein a light absorbing surface of the photovoltaic cell is oriented perpendicular to a face of the display screen, the photovoltaic cell configured to receive at least some of the visible wavelengths of the light emitted from the light source via the first light guide and convert energy of the at least some of the visible wavelengths of light into electrical power.

6. The device of claim 5 , the first light guide further comprising a first photoluminescent material, the first photoluminescent material absorbs light in a first near-infrared wavelength and outputs light in a longer second near-infrared wavelength,
wherein the photovoltaic cell is further configured to:
receive the second near-infrared wavelength and convert energy associated with the second near-infrared wavelength into electrical power.

7. The device of claim 6 , wherein the first photoluminescent material comprises an organic dye or quantum dots.

8. The device of claim 5 , further comprising:
a bezel that is substantially opaque to visible wavelengths of light and substantially transparent to a first near-infrared wavelength; and
a second light guide including a photoluminescent material, the photovoltaic cell being arranged between the first light guide and the second light guide,
wherein:
the photoluminescent material absorbs light having the first near-infrared wavelength via the bezel and outputs absorbed light in a longer second near-infrared wavelength, and
the photovoltaic cell is double-sided and further configured to:
receive the second near-infrared wavelength and convert energy associated with the second near-infrared wavelength into electrical power.

9. The device of claim 5 , further comprising:
a bezel that is substantially opaque to visible wavelengths of light and substantially transparent to a first near-infrared wavelength; and
a second light guide including geometric features to receive light having the first near-infrared wavelength via the bezel and reflect the received light toward the photovoltaic cell,
wherein the photovoltaic cell is double-sided and further configured to receive the first near-infrared wavelength and convert energy associated with the first near-infrared wavelength into electrical power.

10. The device of claim 5 , wherein a portion of the clear cover layer extends beyond the second edge of the first light guide, the device further comprising:
a second light guide including a photoluminescent material, the photovoltaic cell being arranged between the first light guide and the second light guide,
wherein:
the photoluminescent material absorbs incident light having visible wavelengths received via the portion of the clear cover layer and outputs absorbed light in a longer near-infrared wavelength, and
the photovoltaic cell is double-sided and further configured to receive the near-infrared wavelength and convert energy associated with the near-infrared wavelength into electrical power.

11. The device of claim 5 , wherein a portion of the clear cover layer extends beyond the second edge of the first light guide, the device further comprising:
a reflector with a light diffusing surface arranged between the reflective electronic display and the photovoltaic cell, the reflector configured to reflect incident light received via the portion of the clear cover layer toward the photovoltaic cell.

12. The device of claim 5 , wherein the first light guide further comprises a first photoluminescent material, the first photoluminescent material absorbs light in a first near-infrared wavelength and outputs light in a longer second near-infrared wavelength, and the device further comprises:
a bezel that is substantially opaque to visible wavelengths of light and substantially transparent to a third near-infrared wavelength; and
a second light guide including a second photoluminescent material, the photovoltaic cell being arranged between the first light guide and the second light guide,
wherein:
the second photoluminescent material absorbs light

Assignees

• Amazon Tech Inc

Inventors

• Barnes Christopher Dwight
• Alam Mohammed Aftab

Classifications

• H02J7/35 Primary

  with light sensitive cells · CPC title

• Y02E10/52

  PV systems with concentrators · CPC title

• G02B6/4298

  coupling with non-coherent light sources and/or radiation detectors, e.g. lamps, incandescent bulbs, scintillation chambers · CPC title

• G02B6/0003

  the light guides being doped with fluorescent agents · CPC title

• G02B6/0011

  the light guides being planar or of plate-like form · CPC title