Double-Sided Backlight and Assembly Incorporating A Double-Sided Light Source Coupling Light Guide

• US 20080074899A1
• Filed: 09/21/2006
• Published: 03/27/2008
• Est. Priority Date: 09/21/2006
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Yang, Sen, Zhuang, Zhiming, Wang, Andrew
• Granted Patent: US 7,972,051 B2
• Time in Patent Office: Days
• US Class Current: 362/600
• CPC Class Codes: G02B 6/0035 provided on the surface of the light guide or in the bulk of it
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0063 for extracting light out both the major surfaces of the light guide
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02F 1/133342 for double-sided displays
• CPC Class Codes: H04M 1/0214 Foldable telephones, i.e. with body parts pivoting to an open position around an axis parallel to the plane they define in closed position combined with translation movement H04M1/0235
• CPC Class Codes: H04M 2250/16 including more than one display unit

Abstract

Described are a backlight, a backlight assembly for use in an electronic device and an electronic device configured to activate the backlight'"'"'s first light source and to activate the backlight'"'"'s second light source independently of one another. The described double-sided backlight may illuminate either the primary display or the secondary display. The disclosed backlight includes two light sources, each used to direct light in opposite directions from the double-sided backlight. The light guide of the backlight is configured to direct light from the first light source in a first direction to exit the light guide via its first face, and to direct light from the second light source in a second direction different from the first direction to exit the light guide via its second face.

Claims

1. A backlight, comprising:

a light guide having a first face, a second face, and at least a first side surface and a second side surface;

a first light source proximal the first side surface; and

a second light source proximal the second side surface;

wherein the light guide is configured to direct light from the first light source in a first direction to exit the light guide via the first face, and to direct light from the second light source in a second direction different from the first direction to exit the light guide via the second face.

2. The backlight of claim 1, wherein the light guide comprises:

a first prismatic structure on the first face that bends light coming from the first side surface of the light guide towards the first direction; and

a second prismatic structure on the second face that bends light coming from the second side surface of the light guide towards the second direction.

3. The backlight of claim 1, wherein the light guide comprises:

a first material with a first refractive index; and

internal structures comprising a second material with a second refractive index, the second refractive index different from the first refractive index;

wherein;

the light guide comprises primarily the first material; and

the internal structures are configured to direct light from the first light source in a first direction to exit the light guide via the first face, and to direct light from the second light source in a second direction different from the first direction to exit the light guide via the second face.

4. The backlight of claim 1, wherein the first direction is substantially opposite the second direction.

5. The backlight of claim 1, wherein the first side surface is adjacent the second side surface.

6. The backlight of claim 1, wherein the first side surface is substantially opposite the second side surface.

7. The backlight of claim 1, wherein the first light source comprises a set of light emitting devices.

8. The backlight of claim 1, wherein the first light source and the second light source are independently controlled.

9. The backlight of claim 1, wherein the light guide has a thickness approximately between 0.05 millimeter and 4.0 millimeters.

10. The backlight of claim 1, wherein the first face or the second face include a plurality of sub-surfaces having small relative angles to one another.

11. A backlight assembly for use in an electronic device, comprising:

a lightguide frame;

a light guide having a first face, a second face, and at least a first side surface and a second side surface;

a first light source proximal the first side surface; and

a second light source proximal the second side surface;

wherein the light guide further comprises a first prismatic structure on the first face that bends light coming from the first side surface of the light guide towards the first direction, and a second prismatic structure on the second face that bends light coming from the second side surface of the light guide towards the second direction.

12. The backlight assembly of claim 11, wherein the first direction is substantially opposite the second direction.

13. The backlight assembly of claim 11, wherein the first side surface is adjacent the second side surface.

14. The backlight assembly of claim 11, wherein the first side surface is substantially opposite the second side surface.

15. The backlight assembly of claim 11, wherein the first light source and the second light source are independently controlled.

16. The backlight assembly of claim 11, wherein the light guide frame has a thickness approximately between 0.05 millimeter and 4.0 millimeters.

17. An electronic device, comprising:

a controller;

a backlight comprising;

a light guide having a first face, a second face, and a plurality of side surfaces;

a first light source coupled to the controller and proximal a first side surface; and

a second light source coupled to the controller and proximal a second side surface;

wherein the light guide is configured to direct light from the first light source in a first direction to exit the light guide via the first face, and configured to direct light from the second light source in a second direction different from the first direction to exit the light guide via the second face;

a first display coupled to the controller and parallel to the first face; and

a second display coupled to the controller and parallel to the second face;

wherein the controller is configured to activate the first light source and to activate the second light source independently of one another.

18. The device of claim 17, wherein the light guide further comprises:

a first prismatic structure on the first face that bends light coming from the first side surface of the light guide towards the first direction; and

a second prismatic structure on the second face that bends light coming from the second side surface of the light guide towards the second direction.

19. The device of claim 17, wherein the first side surface is adjacent the second side surface.

20. The device of claim 17, wherein the controller is further configured to independently control the first light source and the second light source.