LIGHT COLLIMATION DEVICE, BACKLIGHT MODULE AND DISPLAY DEVICE

• US 20200132907A1
• Filed: 12/13/2018
• Published: 04/30/2020
• Est. Priority Date: 12/15/2017
• Status: Active Grant

• Current Assignee: BOE Technology Group Co., Ltd.
• Original Assignee: BOE Technology Group Co., Ltd.
• Inventors: TAN, Jifeng
• Granted Patent: US 11,378,731 B2
• Time in Patent Office: Days
• CPC Class Codes: G02B 6/0026 Wavelength selective element, sheet or layer, e.g. filter or grating
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02F 1/133602 Direct backlight

Abstract

The present disclosure provides a light collimation device, a backlight module, and a display device, and relates to the field of display technology. The light collimation device includes: a curved reflection member configured to reflect a light from a light source disposed at a focus of the curved reflection member into a light guide member; the light guide member configured to make the light incident into the light guide member propagate by total reflection; and a light extraction structure disposed on the light guide member and configured to extract the light from the light guide member in a collimated manner.

Claims

1. A light collimation device, comprising:

a curved reflection member configured to reflect a light from a light source disposed at a focus of the curved reflection member into a light guide member;

the light guide member configured to make the light incident into the light guide member propagate by total reflection; and

a light extraction structure disposed on the light guide member and configured to extract the light from the light guide member in a collimated manner.

2. The light collimation device according to claim 1, wherein

the curved reflection member comprises a curved surface portion and a flat surface portion adjacent to the curved surface portion, wherein a focus of the curved surface portion is the focus of the curved reflection member;

the flat surface portion is configured to reflect a light reflected by the curved surface portion into the light guide member.

3. The light collimation device according to claim 2, wherein

a reflection layer is disposed on the flat surface portion.

4. The light collimation device according to claim 2, wherein

a reflective light modulation grating is disposed on the flat surface portion and is configured to modulate a light from the light source not reflected by the curved surface portion to be incident into the light guide member and propagate by total reflection in the light guide member.

5. The light collimation device according to claim 3, wherein

a reflective light modulation grating between the curved surface portion and the reflection layer is disposed on the flat surface portion and is configured to modulate a light not reflected by the curved surface portion to be incident into the light guide member and propagate by total reflection in the light guide member.

6. The light collimation device according to claim 4, wherein

the reflective light modulation grating comprises a plurality of areas with different grating periods, wherein the larger an incidence angle of the light not reflected by the curved surface portion for one of the plurality of areas, the smaller a grating period of the one of the plurality of areas.

7. The light collimation device according to claim 4, wherein

light modulated by the reflective light modulation grating is incident into the light guide member at a same incident angle.

8. The light collimation device according to claim 1, wherein

the light guide member comprises a light guide plate comprising a first face and a second face opposite to the first face, wherein an angle between the first face and a main axis of the curved reflection member is configured to make the light incident into the light guide plate propagate by total reflection between the first face and the second face.

9. The light collimation device according to claim 8, wherein

a light modulation layer is disposed on one of the first face and the second face, and the light extraction structure is disposed on the other;

a total reflection angle arcsin(n₂/n₁) at an interface between the light guide plate and the light modulation layer is between θ

₁ and θ

₂, wherein n₁ is a refractive index of the light guide plate, n₂ is a refractive index of the light modulation layer, and θ

₁ and θ

₂ are respectively a minimum incident angle and a maximum incident angle of the light incident into the light guide plate.

10. The light collimation device according to claim 9, wherein

the light extraction structure comprises a plurality of light extraction units spaced apart from each other, and the light collimation device further comprises a planarization layer covering the plurality of light extraction units and filling a gap between adjacent light extraction units;

wherein the planarization layer has a refractive index of n₃ not greater than n₂.

11. The light collimation device according to claim 10, wherein

a total reflection angle arcsin(n₃/n₁) at an interface between the light guide plate and the planarization layer is not greater than θ

₁.

12. The light collimation device according to claim 9, wherein

Arcsin(n₂/n₁)=(θ

₁ θ

₂)/2.

13. The light collimation device according to claim 8, wherein

the light extraction structure is disposed on at least one of the first face or the second face.

14. The light collimation device according to claim 8, wherein

the angle is in a range of 5°

to 15°

.

15. The light collimation device according to claim 1, wherein

the light extraction structure comprises at least one of a grating, a prism, or a lens.

16. The light collimation device according to claim 15, wherein

the grating comprises a plurality of grating units, wherein the closer to the light source for one of the plurality of grating units, the smaller a diffraction efficiency of the one of the plurality of grating units.

17. The light collimation device according to claim 1, wherein

the light guide member has a refractive index same as that of the curved reflection member.

18. A backlight module, comprising:

the light collimation device according to claim 1; and

the light source disposed at the focus of the curved reflection member of the light collimation device.

19. A display device, comprising:

the backlight module according to claim 18.

20. The light collimation device according to claim 5, wherein

the reflective light modulation grating comprises a plurality of areas with different grating periods, wherein the larger an incidence angle of the light not reflected by the curved surface portion for one of the plurality of areas, the smaller a grating period of the one of the plurality of areas.