Backlight unit and display apparatus including the same

Patent metadata

Field	Value
Publication number	US-10989859-B2
Application number	US-201916257599-A
Country	US
Kind code	B2
Filing date	Jan 25, 2019
Priority date	Feb 5, 2018
Publication date	Apr 27, 2021
Grant date	Apr 27, 2021

Abstract

A display apparatus includes a light guide member disposed below a display member. A light source configured to generate light is disposed adjacent to the light guide member. The light guide member includes a plurality of diffraction on the light guide member. The diffraction patterns are spaced apart from each other in the first direction. The plurality of diffraction patterns diffract incident light, which is incident at an incident angle, to change the incident light to diffraction light having a diffraction angle. The incident angle is defined as an angle between the incident light and a normal line that is perpendicular to a top surface or a bottom surface of the light guide member. The diffraction angle, which is defined as an angle between the diffraction light and the normal line, has a magnitude less than that of the incident angle.

First claim

What is claimed is:

1. A display apparatus comprising:
a display member configured to display an image;
a light guide member disposed below the display member; and
a light source configured to generate light and disposed adjacent to the light guide member,
wherein the light guide member comprises a plurality of diffraction patterns disposed on a bottom surface of the light guide member and spaced apart from each other in a first direction,
the plurality of diffraction patterns diffract incident light, which is incident at an incident angle, to change the incident light to diffraction light having a diffraction angle,
the incident angle is defined as an angle between the incident light and a normal line that is perpendicular to a top surface or a bottom surface of the light guide member,
the diffraction angle, which is defined as an angle between the diffraction light and the normal line, has a magnitude less than that of the incident angle,
wherein a reflective member is disposed below the light guide member,
wherein a lower surface of the diffraction patterns contacts the reflective member and an upper surface of the diffractions patterns protrudes above the bottom surface of the light guide member, and
wherein a frequency of the diffraction patterns is λ/(n sin θ 1 −sin θ 2 ),
wherein λ is a wavelength of light incident into the diffraction patterns, n is a refractive index of the light guide member, θ 1 is the angle of the incident light, and θ 2 is the angle of the emitted light.

2. The display apparatus of claim 1 , wherein the diffraction angle is equal to or greater than 0° and equal to or less than about 10°.

3. The display apparatus of claim 2 , wherein each of the diffraction patterns has a rectangular cross-sectional shape.

4. The display apparatus of claim 3 , wherein each of the diffraction patterns has side surfaces that are parallel to each other in the first direction.

5. The display apparatus of claim 4 , wherein each of the parallel side surfaces of each of the diffraction patterns are inclined at an oblique angle from the bottom surface of the light guide member.

6. The display apparatus of claim 5 , wherein the inclined angle has a magnitude equal to or greater than about 20° and equal to or less than about 80°.

7. The display apparatus of claim 2 , wherein the plurality of diffraction patterns are grouped into a diffraction pattern group,
the diffraction pattern group is provided in plurality, and
a distance between the plurality of diffraction pattern groups is equal to or greater than a frequency of the diffraction patterns.

8. The display apparatus of claim 7 , wherein the distance between the plurality of diffraction pattern groups gradually decreases as each of the plurality of diffraction pattern groups are further away from the light source in the first direction.

9. The display apparatus of claim 7 , wherein the display member comprises:
a first substrate on which a plurality of pixels are disposed;
a second substrate disposed on the first substrate and on which a light conversion layer is disposed; and
a liquid crystal layer disposed between the first substrate and the second substrate,
wherein the light conversion layer converts a wavelength band of incident light.

10. The display apparatus of claim 9 , wherein the light source generates first light having a first wavelength band,
the light conversion layer comprises a plurality of first quantum dots configured to convert the first light provided from an optical filter layer into second light having a second wavelength band, and
the first wavelength band has a central wavelength less than that of the second wavelength band.

11. The display apparatus of claim 10 , wherein the light conversion layer further comprises a plurality of second quantum dots configured to convert the first light provided from the optical filter layer into third light having a third wavelength band, and
the third wavelength band has a central wavelength that is less than that of the second wavelength band and greater than that of the first wavelength band.

12. The display apparatus of claim 11 , wherein each of the first quantum dots has a size greater than that of each of the second quantum dots.

13. The display apparatus of claim 12 , wherein the first light is blue light.

14. The display apparatus of claim 10 , wherein the display member further comprises:
a first polarizing layer disposed below the second substrate; and
a second polarizing layer disposed between the liquid crystal layer and the light conversion layer.

15. The display apparatus of claim 1 , wherein each of the plurality of diffraction patterns comprises first to m-th portions disposed on the bottom surface of the light guide member,
the first to m-th portions are sequentially laminated,
the m-th portion is biased in the first direction on the m−1-th portion to expose a portion of the m−1-th portion, and
the m is a natural number greater than about 1.

16. The display apparatus of claim 15 , wherein a side surface of each of the plurality of diffraction patterns in the first direction has a stair shape.

17. The display apparatus of claim 1 , wherein a frequency of the plurality of diffraction patterns is equal to or greater than about 300 nm and equal to or less than about 500 nm.

18. A backlight unit comprising:
a light guide member having a light incident surface defined on a side surface thereof in a first direction;
a light source configured to generate light and disposed adjacent to the light incident surface; and
a reflective member disposed below the light guide member,
wherein the light guide member comprises a plurality of diffraction patterns disposed on a bottom surface of the light guide member, a lower surface of the plurality of diffraction patterns contacts the reflective member and an upper surface of the diffraction patterns protrudes above the bottom surface of the light guide member,
the plurality of diffraction patterns are spaced apart from each other in the first direction, and
diffraction light, which is defined as light diffracted by the plurality of diffraction patterns, forms an angle equal to or greater than 0° and equal to or less than about 10° with a normal line perpendicular to a top surface or a bottom surface of the light guide member, and
wherein a frequency of the diffraction pattern is λ/(n sin θ 1 −sin θ 2 ),
wherein λ is a wavelength of light incident into the diffraction patterns, n is a refractive index of the light guide member, θ 1 is the angle of the incident light, and θ 2 is the angle of the emitted light.

Assignees

• Samsung Display Co Ltd
• Univ Korea Res & Bus Found
• Univ Korea Res & Business Foundation Sejong Campus

Inventors

• Baek Seungin
• Choi Sujin
• Kim Hwi
• Gwon Mira
• Park Youngeun
• Park Jongha
• Yi Junghwan
• Jeon Young Jin
• Choi Jungbeom
• Han Younho

Classifications

• G02F1/133553

  Reflecting elements (associated to illuminating devices G02F1/133605) · CPC title

• G02B6/0055 Primary

  Reflecting element, sheet or layer · CPC title

• G02B6/0036

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

• G02B6/0016 Primary

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

• G02F1/133528

  Polarisers · CPC title