Display apparatus including photoluminescent layer

• US 10,031,276 B2
• Filed: 03/03/2016
• Issued: 07/24/2018
• Est. Priority Date: 03/13/2015
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Inventors: Hirasawa, Taku, Inada, Yasuhisa, Hashiya, Akira, Nitta, Mitsuru, Yamaki, Takeyuki
• Primary Examiner(s): Nguyen, Tuan
• Application Number:
  US15/060,564
• Publication Number:
  US 20160265746A1
• Time in Patent Office: 873 Days
• 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 6/005 provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 33/508 having a non-uniform spatial arrangement or non-uniform concentration, e.g. patterned wavelength conversion layer, wavelength conversion layer with a concentration gradient of the wavelength conversion material

Abstract

A display apparatus includes an excitation light source that outputs excitation light; a light-emitting device including a photoluminescent layer that receives the excitation light and emits light including first light having a wavelength λ_a in air, and a light-transmissive layer located on or near the photoluminescent layer; and an optical shutter on an optical path of the light emitted from the photoluminescent layer. A surface structure is defined on at least one of the photoluminescent layer and the light-transmissive layer, and the surface structure has projections or recesses or both and limits a directional angle of the first light having the wavelength λ_a in air.

Claims

1. A display apparatus comprising:

an excitation light source that outputs excitation light;

a light-emitting device including a photoluminescent layer that receives the excitation light and

emits light including first light having a wavelength λ

_a in air, and a light-transmissive layer located on or near the photoluminescent layer;

an optical shutter on an optical path of the light emitted from the photoluminescent layer;

a color filter array on an incident side of the optical shutter on which the light from the photoluminescent layer is incident or on an output side of the optical shutter from which the light is output, the color filter array including color filters having different transparent wavelength bands; and

a drive circuit that drives the optical shutter in response to an image signal,

wherein a surface structure is defined on at least one of the photoluminescent layer and the light-transmissive layer, and

the surface structure has projections or recesses or both and limits a directional angle of the first light having the wavelength λ

_a in air.

2. The display apparatus according to claim 1, wherein the photoluminescent layer is in contact with the light-transmissive layer.

3. The display apparatus according to claim 1, wherein a center-to-center distance D_int between two adjacent projections or two adjacent recesses in the surface structure and a refractive index n_wav-a of the photoluminescent layer for the first light satisfy λ

_a/n_wav-a<

D_int<

λ

_a.

4. The display apparatus according to claim 1, further comprising a light guide plate that transmits the light from the photoluminescent layer to the optical shutter.

5. The display apparatus according to claim 1, further comprising a light guide plate that transmits the excitation light from the excitation light source to the photoluminescent layer.

6. The display apparatus according to claim 1, further comprising a touch screen on a side of the optical shutter from which light from the photoluminescent layer is output.

7. The display apparatus according to claim 1, wherein the surface structure includes at least one periodic structure, and the at least one periodic structure includes a first periodic structure that satisfies λ

_a/n_wav-a<

p_a<

λ

_a, where n_wav-a is a refractive index of the photoluminescent layer for the first light and p_a is a period of the first periodic structure.

8. The display apparatus according to claim 7, wherein

the light emitted from the photoluminescent layer further includes second light having a wavelength λ

_b different from the wavelength λ

_a in air, and

the at least one periodic structure further includes a second periodic structure satisfying the following relationship;

λ

_b/n_wav-b<

p_b<

λ

_b, where n_wav-b is a refractive index of the photoluminescent layer for the second light, and p_b is a period of the second periodic structure,

the wavelength λ

_a is in a red wavelength band, and

the wavelength λ

_b is in a green wavelength band.

9. The display apparatus according to claim 8, wherein

the at least one periodic structure further includes a third periodic structure that satisfies λ

_c/n_wav-c<

p_c<

λ

_c, where n_wav-c is a refractive index of the photoluminescent layer for third light having a wavelength λ

_c different from λ

_a and λ

_b in air, and p_c is a period of the third periodic structure, and

the wavelength λ

_c is in a blue wavelength band.

10. The display apparatus according to claim 8, wherein the excitation light output from the excitation light source is in a blue wavelength band.

11. The display apparatus according to claim 1, wherein the surface structure includes at least one periodic structure having a period that allows an electric field to be formed in the photoluminescent layer, in which a period of maximum amplitude of the electric field is the same as the period of the at least one periodic structure.

12. The display apparatus according to claim 1, wherein the photoluminescent layer has a thickness that allows a quasi-guided mode to be formed within the photoluminescent layer.

13. The display apparatus according to claim 1, wherein a distance between the light-transmissive layer and the photoluminescent layer is equal to or less than λ

_a/2.

14. A display apparatus comprising:

an excitation light source that outputs excitation light;

a light-emitting device including a photoluminescent layer that receives the excitation light and emits light including first light having a wavelength λ

_a in air; and

an optical shutter on an optical path of the light emitted from the photoluminescent layer;

a color filter array on an incident side of the optical shutter on which the light from the photoluminescent layer is incident or on an output side of the optical shutter from which the light is output, the color filter array including color filters having different transparent wavelength bands; and

a drive circuit that drives the optical shutter in response to an image signal,

wherein a surface structure is defined on the photoluminescent layer, and

the surface structure has projections or recesses or both and limits a directional angle of the first light having the wavelength λ

_a in air.

15. The display apparatus according to claim 14, wherein the surface structure includes at least one periodic structure having a period that allows an electric field to be formed in the photoluminescent layer, in which a period of maximum amplitude of the electric field is the same as the period of the at least one periodic structure.

16. The display apparatus according to claim 14, wherein the photoluminescent layer has a thickness that allows a quasi-guided mode to be formed within the photoluminescent layer.