Coherent backlight unit and three-dimensional image display device including the same

Patent metadata

Field	Value
Publication number	US-2017248747-A1
Application number	US-201715413526-A
Country	US
Kind code	A1
Filing date	Jan 24, 2017
Priority date	Feb 26, 2016
Publication date	Aug 31, 2017
Grant date	—

Abstract

A coherent backlight unit and a 3D image display device including the coherent backlight unit are provided. The coherent backlight unit includes a light source, a light guide plate, a first diffraction grating, a second diffraction grating, and a reflective optical element. The light source irradiates a coherent light and the reflective optical element reflects the coherent light that is propagating toward one of the side surfaces from the inner side of the light guide plate toward the inner side of the light guide plate.

First claim

What is claimed is:

1 . A coherent backlight apparatus comprising:
a light source configured to irradiate a coherent light; a light guide plate that has a flat panel shape, the light guide plate comprising a first flat panel surface and a second flat panel surface; a first diffraction grating provided on one from among the first flat panel surface and the second flat panel surface and configured to diffract the coherent light irradiated from the light source toward an inner side of the light guide plate; a reflective optical element provided on at least one from among a plurality of side surfaces of the light guide plate and configured to reflect the coherent light that propagates toward the at least one from among the plurality of side surfaces from the inner side of the light guide plate toward the inner side of the light guide plate; and a second diffraction grating provided on the first flat panel surface and configured to discharge the coherent light that is totally reflected by the light guide plate to an outside of the light guide plate.

2 . The coherent backlight apparatus of claim 1 , wherein the reflective optical element comprises one from among a mirror surface and a retro-reflective surface.

3 . The coherent backlight apparatus of claim 2 , wherein the retro-reflective surface is provided on only a side surface of the light guide plate.

4 . The coherent backlight apparatus of claim 1 , wherein the first diffraction grating is provided on a first region of the first flat panel surface and the second diffraction grating is provided on a second region of the first flat panel surface.

5 . The coherent backlight apparatus of claim 4 , wherein the light source is positioned so that the coherent light enters the light guide plate through a second flat panel surface that faces the first flat panel surface of the light guide plate.

6 . The coherent backlight apparatus of claim 4 , wherein the first diffraction grating is positioned within a predetermined threshold distance from the second diffraction grating.

7 . The coherent backlight apparatus of claim 6 , wherein the first diffraction grating is provided on a third region of the second flat panel surface, and the second diffraction grating is provided on a second region of the first flat panel surface so as not to face the third region.

8 . The coherent backlight apparatus of claim 1 , wherein each of the first diffraction grating and the second diffraction grating is formed so that an entrance angle of the coherent light with respect to the light guide plate corresponds to an exit angle of the coherent light discharged from the second diffraction grating.

9 . The coherent backlight apparatus of claim 8 , wherein the second diffraction grating is further configured such that when the light source irradiates the coherent light to be perpendicular to the first diffraction grating, the coherent light is discharged by the second diffraction grating toward the second diffraction grating.

10 . The coherent backlight apparatus of claim 8 , wherein, when the light source irradiates the coherent light at an entrance angle between −θ in and +θ in with respect to a perpendicular direction with respect to a surface of the light guide plate, an exit angle of the coherent light discharged via the second diffraction grating is between −θ out and +θ out .

11 . The coherent backlight apparatus of claim 10 , wherein when the entrance angle of the coherent light is −θ in , the exit angle of the coherent light is −θ out , and when the entrance angle of the coherent light is +θ in , the exit angle of the coherent light is +θ out .

12 . The coherent backlight apparatus of claim 10 , wherein the backlight apparatus is configured to satisfy a condition of θ in =θ out .

13 . The coherent backlight apparatus of claim 1 , wherein the light source comprises a red color light source, a blue color light source, and a green color light source.

14 . The coherent backlight apparatus of claim 1 , further comprising a collimator disposed in front of the light source.

15 . The coherent backlight apparatus of claim 1 , further comprising a beam expander disposed in front of the light source.

16 . A coherent backlight apparatus comprising:
a light source configured to irradiate a coherent light; a light guide plate that has a flat panel shape; a first diffraction grating provided on a flat panel surface of the light guide plate and configured to diffract the coherent light irradiated from the light source toward an inner side of the light guide plate; a second diffraction grating provided on a flat panel surface of the light guide plate and configured to discharge the coherent light that is totally reflected by the light guide plate to an outside; and a retro-reflective surface provided at least on one from among a plurality of side surfaces of the light guide plate and configured to form a single optical path for the coherent light that is totally reflected by the light guide plate.

17 . A 3D image display device comprising:
the coherent backlight apparatus of claim 1 ; and a display panel.

18 . The 3D image display device of claim 17 , wherein the display panel comprises:
a display element layer configured to modulate a coherent light discharged from the coherent backlight apparatus in response to a reception of image information; and a lens configured to form a viewing window by focusing the coherent light.

19 . A 3D image display device comprising:
the coherent backlight apparatus of claim 8 ; and a display panel.

20 . The 3D image display device of claim 19 , wherein the display panel comprises:
a display element layer configured to modulate a coherent light discharged from the coherent backlight apparatus in response to a reception of image information; and a lens configured to focus the coherent light and to provide a left-eye image and a right-eye image, which are different from each other, to a left eye and a right eye of a viewer, respectively, according to an exit angle of the coherent light discharged from the coherent backlight apparatus.

Assignees

• Samsung Electronics Co Ltd

Inventors

• Kim Yunhee
• Song Hoon
• Kim Sunil
• Song Seokho

Classifications

• G03H1/2286

  Particular reconstruction light (G03H1/24 takes precedence); Beam properties · CPC title

• G02B30/27

  involving lenticular arrays · CPC title

• G03H2223/16

  Optical waveguide, e.g. optical fibre, rod · CPC title

• G02B6/34

  utilising prism or grating {(G02B6/293 takes precedence)} · CPC title

• G02B27/425

  in illumination systems (mask illumination systems in photolithographic systems G03F7/70158) · CPC title