Directional backlight unit and image display apparatus including the same

Patent metadata

Field	Value
Publication number	US-2018128962-A1
Application number	US-201715656349-A
Country	US
Kind code	A1
Filing date	Jul 21, 2017
Priority date	Nov 8, 2016
Publication date	May 10, 2018
Grant date	—

Abstract

A directional backlight unit and an image display apparatus including the directional backlight unit are provided. The directional backlight unit includes at least one light source and a light guide plate that guides light emitted by the light source. An interval between grating patterns formed on the light guide plate satisfies at least one condition of a first range and a second range in order to minimize a spreading of light caused by the grating patterns.

First claim

What is claimed is:

1 . A directional backlight unit comprising:
at least one light source configured to emit light; and a light guide plate configured to guide the light emitted by the at least one light source, wherein a plurality of grating patterns are provided on an exit surface of the light guide plate, each grating pattern from among the plurality of grating patterns being configured to cause the light to travel in a respective predetermined direction, and wherein an interval between adjacent grating patterns from among the plurality of grating patterns satisfies at least one condition from among a first range less than 1/10 of a wavelength of the light emitted by the light source and a second range greater than 180/π times the wavelength of the light emitted by the light source.

2 . The directional backlight unit of claim 1 , wherein the wavelength of the light emitted by the light source is within a range of between 380 nm and 780 nm.

3 . The directional backlight unit of claim 2 , wherein the interval between the adjacent grating patterns satisfies at least one condition from among a third range less than 50 nm and a fourth range greater than 30 μm.

4 . The directional backlight unit of claim 1 , wherein the plurality of grating patterns comprises a plurality of panel-oriented grating patterns that form directivities toward a plurality of viewing zones, and a plurality of dummy grating patterns respectively disposed between adjacent panel-oriented grating patterns from among the plurality of panel-oriented grating patterns.

5 . The directional backlight unit of claim 4 , further comprising a dummy light blocking layer comprising a plurality of light blocking regions that are configured to block light that propagates from each of the plurality of dummy grating patterns.

6 . The directional backlight unit of claim 4 , wherein an average refractive index of each dummy grating pattern from among the plurality of dummy grating patterns is substantially identical to an average refractive index of at least one panel-oriented grating pattern from among the plurality of panel-oriented grating patterns that is adjacent to each dummy grating pattern from among the plurality of dummy grating patterns.

7 . The directional backlight unit of claim 6 , wherein at least one from among a pitch of a grating and a direction of a grating of each dummy grating pattern from among the plurality of dummy grating patterns is different from at least one from among a pitch of a grating and a direction of at least one panel-oriented grating pattern from among the plurality of panel-oriented grating patterns that is adjacent to each dummy grating pattern from among the plurality of dummy grating patterns.

8 . The directional backlight unit of claim 4 , wherein a light emission efficiency of each dummy grating pattern from among the plurality of dummy grating patterns is lower than a light emission efficiency of each panel-oriented grating pattern from among the plurality of panel-oriented grating patterns.

9 . The directional backlight unit of claim 1 , wherein the at least one light source comprises a plurality of light sources configured to emit light of different wavelengths, wherein at least two grating patterns from among the plurality of grating patterns selectively refract the light of the different wavelengths.

10 . An image display apparatus comprising:
at least one light source configured to emit light; a light guide plate configured to guide the light emitted by the at least one light source; and a display panel configured to form an image by using the light guided by the light guide plate, wherein a plurality of grating patterns are formed on an exit surface of the light guide plate, each grating pattern from among the plurality of grating patterns being configured to cause the light to travel in a respective predetermined direction, and wherein an interval between adjacent grating patterns from among the plurality of grating patterns satisfies at least one condition from among a first range less than 1/10 of a wavelength of the light emitted by the light source and a second range greater than 180/π times the wavelength of the light emitted by the light source.

11 . The image display apparatus of claim 10 , wherein the wavelength of the light emitted by the light source is within a range of between 380 nm and 780 nm.

12 . The image display apparatus of claim 10 , wherein the interval between the adjacent grating patterns satisfies at least one condition from among the first range and a third range greater than 30 μm.

13 . The image display apparatus of claim 10 , wherein the plurality of grating patterns comprises a plurality of panel-oriented grating patterns that form orientations toward a plurality of viewing zones and a plurality of dummy grating patterns respectively disposed between adjacent panel-oriented grating patterns from among the plurality of panel-oriented grating patterns.

14 . The image display apparatus of claim 13 , wherein the plurality of dummy grating patterns are configured to prevent light that propagates from each dummy grating pattern from among the plurality of dummy grating patterns from being used to form the image.

15 . The image display apparatus of claim 13 , wherein the plurality of dummy grating patterns are configured to direct light that propagates from each dummy grating pattern from among the plurality of dummy grating patterns outside a viewing angle of the display panel.

16 . The image display apparatus of claim 13 , further comprising a dummy light blocking layer comprising a plurality of light blocking regions configured to prevent light that propagates from each dummy grating pattern from among the plurality of dummy grating patterns from being incident upon the display panel.

17 . The image display apparatus of claim 13 , wherein the plurality of dummy grating patterns are configured such that a respective wavelength band selected in each dummy grating pattern from among the plurality of dummy grating patterns is different from a respective wavelength band of a pixel oriented by each dummy grating pattern from among the plurality of dummy grating patterns.

18 . The image display apparatus of claim 13 , wherein a respective average refractive index of each dummy grating pattern from among the plurality of dummy grating patterns is substantially identical to an average refractive index of at least one panel-oriented grating pattern from among the plurality of panel-oriented grating patterns that is adjacent to each dummy grating pattern from among the plurality of dummy grating patterns.

19 . The image display apparatus of claim 18 , wherein at least one from among a pitch of a grating and a direction of a grating of each dummy grating pattern from among the plurality of dummy grating patterns is different from at least one from among a pitch of grating and a direction of a grating of at least one panel oriented grating patter from among the plurality of panel-oriented grating patterns that is adjacent to each dummy grating pattern from among the plurality of dummy grating patterns.

20 . The image display apparatus of claim 13 , wherein a light emission efficiency of each dummy grating pattern from among the plurality of dummy grating patterns is lower than a light emission efficiency of each panel-oriented grating pattern from among the plurality of panel-oriented grating patterns.

Assignees

• Samsung Electronics Co Ltd

Inventors

• Kim Hyunjoon
• Shin Bongsu
• Kim Dongouk
• Park Joonyong
• Bae Jihyun
• Shim Dongsik
• Lee Sunghoon
• Chung Jaeseung
• Song Seokho

Classifications

• G02B6/0035 Primary

  provided on the surface of the light guide or in the bulk of it · CPC title

• G02B6/005

  provided by one optical element, or plurality thereof, placed on the light output side of the light guide · CPC title

• G02B6/0061 Primary

  to provide homogeneous light output intensity · CPC title

• G02B6/0068

  Arrangements of plural sources, e.g. multi-colour light sources · CPC title

• G02B6/0036

  2-D arrangement of prisms, protrusions, indentations or roughened surfaces · CPC title