Display backlight with diffractive and refractive light scattering structures

• US 9,835,786 B2
• Filed: 08/15/2012
• Issued: 12/05/2017
• Est. Priority Date: 08/15/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Qi, Jun, Yin, Victor H., Chen, Wei
• Primary Examiner(s): Nguyen, Lauren
• Application Number:
  US13/586,573
• Publication Number:
  US 20140049726A1
• Time in Patent Office: 1,938 Days
• Field of Search: 349 65
• CPC Class Codes: G02B 6/0016 Grooves, prisms, gratings, scattering particles or rough surfaces
• CPC Class Codes: G02B 6/0043 provided on the surface of the light guide
• CPC Class Codes: G02B 6/0065 Manufacturing aspects; Material aspects
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side

Abstract

An electronic device display may have display layers that provide images for a user. Backlight structures may provide backlight for the display layers. The backlight structures may include a light source such as an array of light-emitting diodes. A light guide plate in the backlight structures may be used to distribute the light from the light-emitting diodes throughout the display. The light guide plate may have a main rectangular area that overlaps the display. The main rectangular area may have refractive light scattering structures such as a layer containing clear beads. The refractive light scattering structures may scatter light from the light guide plate for use as backlight. A strip of light diffracting structures such as holographic structures or grating structures may be used to mix light from the light-emitting diodes along the border of the light guide plate.

Claims

1. A display, comprising:

display layers that display images; and

backlight structures that provide backlight for the display layers, wherein the backlight structures include a light source that emits light and a light guide plate that receives the light from the light source, wherein the light guide plate has a first region with refractive light scattering structures that scatter the light from the light source to serve as the backlight and has a second region interposed between the first region and the light source, wherein the second region has diffractive light scattering structures that mix the light before the light is scattered by the refractive light scattering structures, wherein the diffractive light scattering structures comprise holographic structures that are formed of a different material than the light guide plate, wherein the light guide plate has opposing first and second surfaces, wherein the refractive light scattering structures are formed on the first surface, and wherein the diffractive light scattering structures are formed on the second surface.

2. The display defined in claim 1 wherein the refractive light scattering structures comprise clear beads.

3. The display defined in claim 1 wherein the display layers overlap the first region and wherein the second region forms a strip that runs along a peripheral edge of the first region.

4. The display defined in claim 1 wherein the diffractive light scattering structures comprise a patterned layer of resin formed in a strip running along a border of the light guide plate.

5. The display defined in claim 4 wherein the resin comprises ultraviolet-light-curable resin.

6. The display defined in claim 5 wherein the refractive light scattering structures comprise clear beads.

7. The display defined in claim 6 wherein the patterned layer of resin is formed on the second surface and wherein the clear beads are formed on the first surface.

8. The display defined in claim 7 wherein the light source comprises light-emitting diodes.

9. The display defined in claim 8 wherein the display layers include a liquid crystal layer.

10. The display defined in claim 9 wherein the display layers include a color filter layer and a thin-film-transistor layer and wherein the liquid crystal layer is interposed between the color filter layer and the thin-film-transistor layer.

17. The display defined in claim 10 wherein the light-emitting diodes are configured to launch light towards the light guide plate along a first dimension, wherein the backlight passes through the display layers along a second dimension that is perpendicular to the first dimension, and wherein the diffractive light scattering structures mix the light from the light source with respect to a third dimension that is perpendicular to the first dimension and the second dimension.

11. A display, comprising:

at least one display layer;

a light guide plate that provides backlight for the display layer, wherein the light guide plate has a first surface that emits light towards the at least one display layer, a second surface opposite the first surface, and a rectangular periphery with four edge surfaces; and

light-emitting diodes arranged along a given one of the four edge surfaces that emit light into the light guide plate through the given one of the four edge surfaces, wherein the light guide plate has a rectangular region containing light scattering structures formed on the first surface that scatter the light so that the light serves as the backlight for the display layer, wherein the light guide plate has a border region between the rectangular region and the given edge, wherein the light guide plate includes diffractive light guide structures formed on the second surface in the border region that mix the light by diffraction, wherein the light scattering structures comprise refractive light scattering structures that are formed in the border region and that overlap the diffractive light guide structures, and wherein the diffractive light guide structures have an index of refraction that is different than an index of refraction of the light guide plate.

12. The display defined in claim 11 wherein the diffractive light guide structures comprise a layer of resin on the second surface of the light guide plate.

13. The display defined in claim 12 wherein the layer of resin comprises a layer of ultraviolet-light-curable resin with a holographic pattern.

14. The display defined in claim 12 wherein the layer of resin comprises a layer of ultraviolet-light-curable resin with a grating pattern.

18. The display defined in claim 12 wherein the refractive light scattering structures refract the light without diffracting the light.

19. The method defined in claim 11, wherein the refractive light scattering structures have a maximum width less than or equal to 12 microns.

15. A display, comprising:

an upper polarizer;

a lower polarizer;

a thin-film-transistor layer between the upper and lower polarizers;

a color filter layer between the upper and lower polarizers;

a liquid crystal layer between the thin-film transistor layer and the color filter layer;

a light guide plate having edges and a border strip of diffractive light scattering structures that runs along one of the edges, wherein the diffractive light scattering structures comprise a layer of resin deposited on a surface of the light guide plate, wherein the light guide plate has a main region that includes refractive light scattering structures, wherein the diffractive light scattering structures and the refractive light scattering structures do not overlap, wherein the layer of resin and the light guide plate are formed of different materials, and wherein the liquid crystal layer overlaps the border strip of diffractive light scattering structures; and

an array of light-emitting diodes that emits light into the light guide plate, wherein the diffractive light scattering structures mix the light.

16. The display defined in claim 15 wherein the refractive light scattering structures scatter the light that is mixed by the diffractive light scattering structures so that the light passes through the liquid crystal layer and wherein the border strip is located between the array of light-emitting diodes and the main region.