Liquid crystal display device that switches between a transparent state and an opaque state comprising first and second light sources

Patent metadata

Field	Value
Publication number	US-9798062-B2
Application number	US-201514812735-A
Country	US
Kind code	B2
Filing date	Jul 29, 2015
Priority date	Aug 25, 2014
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

A display device has a liquid crystal panel that switches between a transparent state and an opaque state, a first light source, a light guide plate arranged on a back surface of the liquid crystal panel and made of a transparent material, the light guide plate having an incident surface facing the first light source and an outgoing surface facing the back surface of the liquid crystal panel, propagating light emitted from the first light source and incident through the incident surface, and outputting the light toward the liquid crystal panel from the outgoing surface, and a second light source configured to illuminate an object arranged on an opposite side to the liquid crystal panel with the light guide plate interposed therebetween.

First claim

The invention claimed is:

1. A display device comprising:
a liquid crystal panel that switches between a transparent state and an opaque state;
a first light source;
a light guide plate arranged on a back surface of the liquid crystal panel and made of a transparent material, the light guide plate comprising an incident surface facing the first light source and an outgoing surface facing the back surface of the liquid crystal panel, propagating light emitted from the first light source and incident through the incident surface, and outputting the light toward the liquid crystal panel from the outgoing surface;
a second light source configured to illuminate an object arranged on an opposite side to the liquid crystal panel with the light guide plate interposed therebetween; and
a controller configured to put the liquid crystal panel into the opaque state when the first light source is lit, to put the liquid crystal panel into the transparent state when the second light source is turned off while the second light source is lit, and to turn off the first light source.

2. The display device according to claim 1 ,
wherein a plurality of patterns are formed in at least one of the outgoing surface of the light guide plate and a surface on opposite side to the outgoing surface, and
wherein the plurality of patterns is formed into a shape that reflects or refracts the light propagating through the light guide plate such that the light output from the outgoing surface, and an area ratio of a region where the plurality of patterns are formed to the surface in which the plurality of patterns are formed is less than or equal to 30%.

3. The display device according to claim 2 ,
wherein the plurality of patterns are arrayed at predetermined intervals along a propagation direction of the light from the first light source in the surface on the opposite side to the outgoing surface, and
wherein each of the plurality of patterns comprises a reflecting surface that is inclined with respect to the surface on the opposite side to the outgoing surface by an angle at which the light, which is emitted from the first light source and incident on the light guide plate from the incident surface, is totally reflected toward the outgoing surface.

4. The display device according to claim 3 ,
wherein the light guide plate comprises a second incident surface that is formed so as to face the incident surface with the plurality of patterns interposed therebetween,
wherein the first light source comprises a first light emitting element that is arranged so as to face the incident surface and a second light emitting element that is arranged so as to face the second incident surface, and
wherein each of the plurality of patterns further comprises a second reflecting surface that is inclined with respect to the surface on the opposite side to the outgoing surface by an angle at which the light, which is emitted from the second light emitting element and incident on the light guide plate from the second incident surface, is totally reflected toward the outgoing surface.

5. The display device according to claim 1 , wherein a haze value of the light guide plate to the light, which is incident on the light guide plate from the surface on the opposite side to the outgoing surface and transmitted onto the outgoing surface side, is less than or equal to 28%.

6. The display device according to claim 1 , further comprising:
a direction-selective light shielding member formed into a sheet shape between the light guide plate and the object,
wherein the direction-selective light shielding member comprises a first surface facing the light guide plate and a second surface facing the object,
wherein the direction-selective light shielding member comprises, inside thereof, a plurality of opaque members arranged at predetermined intervals along the propagation direction of the light from the first light source, and
wherein the plurality of opaque members being extended in a direction intersecting the propagation direction.

7. The display device according to claim 2 , wherein a haze value of the light guide plate to the light, which is incident on the light guide plate from the surface on the opposite side to the outgoing surface and transmitted onto the outgoing surface side, is less than or equal to 28%.

8. The display device according to claim 3 , wherein a haze value of the light guide plate to the light, which is incident on the light guide plate from the surface on the opposite side to the outgoing surface and transmitted onto the outgoing surface side, is less than or equal to 28%.

9. The display device according to claim 4 , wherein a haze value of the light guide plate to the light, which is incident on the light guide plate from the surface on the opposite side to the outgoing surface and transmitted onto the outgoing surface side, is less than or equal to 28%.

10. The display device according to claim 2 , further comprising:
a direction-selective light shielding member formed into a sheet shape between the light guide plate and the object,
wherein the direction-selective light shielding member comprises a first surface facing the light guide plate and a second surface facing the object,
wherein the direction-selective light shielding member comprises, inside thereof, a plurality of opaque members arranged at predetermined intervals along the propagation direction of the light from the first light source, and
wherein the plurality of opaque members being extended in a direction intersecting the propagation direction.

11. The display device according to claim 3 , further comprising:
a direction-selective light shielding member formed into a sheet shape between the light guide plate and the object,
wherein the direction-selective light shielding member comprises a first surface facing the light guide plate and a second surface facing the object,
wherein the direction-selective light shielding member comprises, inside thereof, a plurality of opaque members arranged at predetermined intervals along the propagation direction of the light from the first light source, and
wherein the plurality of opaque members being extended in a direction intersecting the propagation direction.

12. The display device according to claim 4 , further comprising:
a direction-selective light shielding member formed into a sheet shape between the light guide plate and the object,
wherein the direction-selective light shielding member comprises a first surface facing the light guide plate and a second surface facing the object,
wherein the direction-selective light shielding member comprises, inside thereof, a plurality of opaque members arranged at predetermined intervals along the propagation direction of the light from the first light source, and
wherein the plurality of opaque members being extended in a direction intersecting the propagation direction.

13. The display device according to claim 5 , further comprising:
a direction-selective light shielding member formed into a sheet shape between the light guide plate and the object,
wherein the direction-selective light shielding member comprises a first surface facing the light guide plate and a second surface facing the object,
wherein the direction-selective light shielding member comprises, inside thereof, a plurality of opaque members arranged at predetermined intervals along the propagation direction of the light from the first light source, and
wherein the plurality of opaque members being extended in a direction intersecting the propagation direction.

Assignees

• Omron Tateisi Electronics Co

Inventors

• Kitamura Norikazu
• Osumi Yoshimasa
• Tanoue Yasuhiro
• Takagi Yoshihiko
• Kanzaki Norihisa
• Shinohara Masayuki
• Fujita Junya
• Ishikawa Takamitsu
• Kakinuma Takeshi
• Kishimoto Jun
• Hiramatsu Masaaki

Classifications

• G02B6/0016 Primary

  Grooves, prisms, gratings, scattering particles or rough surfaces · CPC title

• G02B6/0036 Primary

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