Backlight unit and holographic display including the same

Patent metadata

Field	Value
Publication number	US-10523926-B2
Application number	US-201514673987-A
Country	US
Kind code	B2
Filing date	Mar 31, 2015
Priority date	Sep 1, 2014
Publication date	Dec 31, 2019
Grant date	Dec 31, 2019

Abstract

Provided are a backlight unit and a holographic display including the same. The backlight unit may include: a light guide plate; a light source unit configured to adjust a direction of light which is emitted from the light source unit and incident on the light guide plate; and a diffraction device which is disposed on the light guide plate and configured to control a direction of light emitted from the light guide plate.

First claim

What is claimed is:

1. A backlight unit comprising:
a light guide plate;
a light source unit configured to emit light to the light guide plate and adjust an incidence direction of the light to be incident on the light guide plate in the incidence direction; and
a diffraction device which is disposed on and in contact with the light guide plate and configured to control an output direction of the light to be outputted from the diffraction device in the output direction,
wherein the light source unit is further configured to change an incidence angle of the light to be incident on the light guide plate and the diffraction device is further configured to control the output direction of the light according to the incidence angle of the light, and
wherein light incident on the diffraction device in a first incidence angle by the light source unit passes through t ea spatial light modulator to display an image in a first viewing area, and light incident on the diffraction device in a second incidence angle by the light source unit passes through the spatial light modulator to display an image in a second viewing area, and
wherein both the light source unit and the diffraction device are provided in the output direction of the light on the light guide plate and an area of the diffraction device is wider than an area of the light guide plate on which the light from the light source unit is incident.

2. The backlight unit of claim 1 , wherein the light source unit comprises a plurality of light sources, and each of the plurality of light sources is arranged to have different light output directions.

3. The backlight unit of claim 1 , wherein the light source unit comprises:
at least one light source; and
a beam steering unit that adjusts a light output direction of the at least one light source.

4. The backlight unit of claim 3 , wherein the beam steering unit comprises a first driver that rotates the at least one light source.

5. The backlight unit of claim 3 , wherein the beam steering unit comprises:
a mirror that reflects the light emitted from the at least one light source to be incident on the light guide plate; and
a second driver that rotates the mirror.

6. The backlight unit of claim 3 , wherein the beam steering unit comprises:
a refraction surface that refracts light emitted from the at least one light source to be incident on the light guide plate; and
an active optical element that adjusts an incidence angle of light incident on the light guide plate based on a tilt angle of the refraction surface.

7. The backlight unit of claim 6 , wherein the active optical element comprises an electrowetting prism or a refractive index converting device.

8. The backlight unit of claim 6 , wherein the active optical element comprises a first medium and a second medium which are stacked on each other and form the refraction surface over which the first medium and the second medium contact.

9. The backlight unit of claim 6 , wherein the tilt angle of the refraction surface is controlled by a voltage applied to the active optical element.

10. The backlight unit of claim 1 , wherein the light source unit comprises a coherent light source.

11. The backlight unit of claim 1 , wherein the diffraction device comprises a diffracting grating that is disposed on the light guide plate, and the diffracting grating changes an angle at which the light is emitted from the light guide plate.

12. The backlight unit of claim 1 , further comprising:
a 2-dimensional (2D) light guide plate disposed below the light guide plate; and
a light source that radiates light to the 2D light guide plate.

13. A holographic display comprising:
a light guide plate;
a light source unit configured to emit light to the light guide plate and adjust an incidence direction of the light to be incident on the light guide plate in the incidence direction;
a diffraction device which is disposed on and in contact with the light guide plate and configured to control an output direction of the light to be outputted from the diffraction device in the output direction; and
a spatial light modulator that displays a holographic image by modulating a beam that passed through the diffraction device,
wherein the light source unit is further configured to change an incidence angle of the light to be incident on the light guide plate and the diffraction device is further configured to control the output direction of the light according to the incidence angle of the light,
wherein light incident on the diffraction device in a first incidence angle by the light source unit passes through the spatial light modulator to display an image in a first viewing area, and light incident on the diffraction device in a second incidence angle by the light source unit passes through the spatial light modulator to display an image in a second viewing area, and
wherein both the light source unit and the diffraction device are provided in the output direction of the light on the light guide plate and an area of the diffraction device is wider than an area of the light guide plate on which the light from the light source unit is incident.

14. The holographic display of claim 13 , wherein the light source unit comprises a plurality of light sources, and the plurality of light sources are arranged to have different light output directions.

15. The holographic display of claim 13 , wherein the light source unit comprises:
at least one light source; and
a beam steering unit that adjusts a light output direction of the at least one light source.

16. The holographic display of claim 15 , wherein the beam steering unit comprises a first driver that rotates the at least one light source.

17. The holographic display of claim 15 , wherein the beam steering unit comprises:
a mirror that reflects light emitted from the at least one light source to be incident on the light guide plate; and
a second driver that rotates the mirror.

18. The holographic display of claim 15 , wherein the beam steering unit comprises:
a refraction surface that refracts light emitted from the at least one light source to be incident on the light guide plate; and
an active optical element that adjusts an incidence angle of light incident on the light guide plate based on a tilt angle of the refraction surface.

19. The holographic display of claim 18 , wherein the active optical element comprises an electrowetting prism or a refractive index converting device.

20. The holographic display of claim 13 , wherein the light source unit comprises a coherent light source.

21. The holographic display of claim 13 , further comprising:
a sensor configured to track we-eyes of a viewer; and
a controller configured to control the light source unit to adjust the incidence direction of the light according to a signal detected by the sensor.

22. The holographic display of claim 13 , further comprising:
a 2-dimensional (2D) light guide plate disposed below the light guide plate; and
a light source that radiates light to the 2D light guide plate.

Assignees

• Samsung Electronics Co Ltd

Inventors

• Kim Sunil
• Choi Chilsung
• An Jungkwuen
• Morozov Alexander V
• Lee Hongseok
• Putilin Andrey N
• Dubinin German B
• Dubynin Sergey E

Classifications

• G03H1/0005 Primary

  Adaptation of holography to specific applications (holographic optical element G02B5/32; holographic scanner G02B26/106; recognition using holographic mask G06V10/88; holographic memories G11B7/0065, G11C13/042) · CPC title

• G03H2225/33

  Complex modulation · CPC title

• G03H2223/23

  Diffractive element · CPC title

• G03H2001/2226

  Edge lit holograms · CPC title

• G03H2001/221

  Element having optical power, e.g. field lens · CPC title