LIGHT GUIDES AND BACKLIGHT SYSTEMS INCORPORATING PRISMATIC STRUCTURES AND LIGHT REDIRECTORS

• US 20130250619A1
• Filed: 05/10/2013
• Published: 09/26/2013
• Est. Priority Date: 04/18/2008
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Pixtronix, Incorporated (Qualcomm, Inc.)
• Inventors: Kim, Je Hong, Gandhi, Jignesh
• Granted Patent: US 9,243,774 B2
• Time in Patent Office: Days
• US Class Current: 362/626
• CPC Class Codes: F21V 7/04 Optical design
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02B 6/0061 to provide homogeneous light output intensity

Abstract

Improved apparatus and method for collecting and directing light from a source via a light guide and modulated display assembly in an efficient manner through the design and use of prismatic optical structures, diffusers and/or light redirectors.

Claims

1. A display comprising;

an array of light modulators defining a display surface;

a light guide having front and rear surfaces and a plurality of geometric light redirectors formed within the light guide;

a first layer of prisms;

a second layer of prisms; and

each of the first layer of prisms and second layer of prisms being located between the light guide and the display surface.

2. The display of claim 1, wherein the first layer of prisms includes a plurality of front-facing prisms and the second layer of prisms includes a plurality of rear-facing prisms.

3. The display of claim 1, wherein the first layer of prisms form a front-facing prism sheet, and the second layer of prisms form a rear-facing prism sheet.

4. The display of claim 3, further comprising a diffuser located between the rear-facing and front-facing prism sheets.

5. The display of claim 3, further comprising a diffuser located between the light guide and the rear-facing prism sheet.

6. The display of claim 1, wherein the array of light modulators includes a plurality of MEMS-based light modulators.

7. The display of claim 1, wherein the geometric light redirectors are spatially configured to create a predefined angular distribution of light.

8. The display of claim 7, wherein the first layer of prisms and second layer of prisms are arranged so as to not substantially alter the angular distribution of the light created by the geometric light redirectors.

9. The display of claim 1, wherein the second layer of prisms is located between the first layer of prisms and the front surface of the light guide.

10. The display of claim 1, wherein the array of light modulators includes one of a plurality of liquid crystal based light modulators, a plurality of rolling actuator based light modulators, and a plurality of electrowetting light modulators.

11. The display of claim 1, wherein the first layer of prisms and the second layer of prisms form opposing sides of a single prism sheet.

12. The display of claim 1, wherein the first and second layers of prisms are contained entirely within an optical cavity.

13. The display of claim 1, wherein a front-facing reflective layer is provided behind the rear surface of the light guide.

14. The display of claim 1, wherein a rear-facing reflective layer is provided between the array of light modulators and the first layer of prisms.

15. The display of claim 1 wherein the orientation of the first layer of prisms is rotated up to 45 degrees with respect to the orientation of the second layer of prisms.

16. A method of manufacturing a display, comprising:

providing a light guide including a plurality of geometric light redirectors within the light guide;

providing an array of light modulators to define a display surface;

providing a first layer of prisms adjacent to the light guide; and

providing a second layer of prisms adjacent to the array of light modulators.

17. The method of claim 16, comprising aligning an orientation of at least one of the first layer of prisms and the second layer of prisms with respect to an orientation of the geometric light redirectors of the light guide to adjust the intensity of emitted light normal to the display assembly.

18. The method of claim 17, wherein aligning the orientation includes rotating the orientation of the at least one prism of the first layer of prisms and one prism of the second layer of prisms with respect to the orientation of the geometric light redirectors.

19. The method of claim 18, further comprising aligning the orientation of the first layer of prisms with respect to the orientation of the second layer of prisms.

20. The method of claim 19, further comprising rotating the first layer of prisms up to 45 degrees with respect to the second layer of prisms.