REFLECTION SHEET, BACKLIGHT UNIT, LIQUID CRYSTAL DISPLAY DEVICE, AND MANUFACTURING METHOD THEREOF

• US 20140146560A1
• Filed: 07/09/2013
• Published: 05/29/2014
• Est. Priority Date: 11/23/2012
• Status: Abandoned Application

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: KIM, Dong Hoon, CHOI, Young Jun
• Application Number:
  US13/937,788
• Publication Number:
  US 20140146560A1
• Time in Patent Office: Days
• US Class Current: 362/606
• CPC Class Codes: F21V 7/05 plane
• CPC Class Codes: G02B 5/0221 the surface having an irregular structure G02B5/0226 takes precedence
• CPC Class Codes: G02B 5/0226 having particles on the surface
• CPC Class Codes: G02B 5/0284 used in reflection
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0065 Manufacturing aspects; Material aspects

Abstract

A reflection sheet of display backlighting unit is designed to be spaced apart by a predetermined gap distance from an overlying optical layer. However, the reflection sheet may inadvertently come into at least partial contact with the overlying optical layer. The reflection sheet is configured to avoid the creation of line contacts and wide area contacts with the optical layer. More specifically, the reflection sheet includes an upper skin layer having particles embedded therein. An average of surface roughness or height differences of the protrusions is caused to have a value of 15 μm or larger, and an interval between the adjacent protrusions is caused to be 200 μm or less.

Claims

1. A reflection sheet, comprising:

a main body; and

an upper skin layer positioned on an upper surface of the main body, the upper skin layer comprising a plurality of particles,

wherein irregular protrusions are formed on a top surface of the upper skin layer due to the presence of the particles,

wherein an average of surface roughness or height differences of the protrusions has a value of 15 μ

m or larger, and

wherein an interval between the adjacent protrusions has a value of 200 μ

m or less.

2. The reflection sheet of claim 1, wherein:

the average of surface roughness or height differences of the protrusions has a value not more than a predetermined gap distance designed for spacing apart of the reflection sheet from a optical processing layer,

the interval between the adjacent protrusions has a value not less than a maximum diameter of a majority of the particles, and

the maximum diameter of at least the majority the particles is 15 μ

m or larger but not more than the predetermined gap distance.

3. The reflection sheet of claim 2, further comprising:

a lower skin layer disposed on a lower surface of the main body, the lower surface being opposed to the upper surface of the main body.

4. The reflection sheet of claim 2, wherein:

at least some of the particles are disposed within the main body.

5. The reflection sheet of claim 1, wherein:

the main body has reflection providing globules or bubbles defined therein.

6. A backlight unit, comprising:

a light source configured to provide light;

a light guide plate configured to guide the light provided from the light source;

at least one optical film positioned at an upper side of the light guide plate; and

a reflection sheet positioned at a lower side of the light guide plate and configured to reflect light to an upper portion, wherein the reflection sheet is designed for preferably being spaced apart from the lower side of the light guide plate by a predetermined gap distance and

wherein the reflection sheet comprises;

a main body; and

an upper skin layer positioned on an upper surface of the main body, the upper skin layer comprising a plurality of particles,

wherein irregular protrusions are formed on a top surface of the upper skin layer due to the presence of the particles,

wherein an average of surface roughness or height differences of the protrusions has a value of 15 μ

m or larger, and

wherein an interval between the adjacent protrusions has a value of 200 μ

m or less.

7. The backlight unit of claim 6, wherein:

the main body has reflection providing globules or bubbles defined therein, and

the average of surface roughness or height differences of the protrusions has a value not more than a predetermined gap distance designed for spacing apart of the reflection sheet from the light guide plate,

the interval between the adjacent protrusions has a value not less than a maximum diameter of a majority of the particles, and

the maximum diameter of at least a majority of the particles is 15 μ

m or larger.

8. The backlight unit of claim 7, further comprising:

a lower skin layer disposed on the other surface of the main body.

9. The backlight unit of claim 7, wherein:

a part of the plurality of particles is disposed within the main body.

10. A display device, comprising:

a light receiving display panel; and

a backlight unit configured to provide the light receiving display panel with light,

wherein the backlight unit comprises;

a light source configured to provide light;

a light guide plate configured to guide the light provided from the light source;

at least one optical film positioned at an upper side of the light guide plate; and

a reflection sheet positioned at a lower side of the light guide plate and configured to reflect light to an upper portion of the light guide plate,

the reflection sheet comprises;

a main body; and

an upper skin layer positioned on an upper surface of the main body, the upper skin layer comprising a plurality of particles,

wherein irregular protrusions are formed on a top surface of the upper skin layer due to the presence of the particles,

wherein an average of surface roughness or height differences of the protrusions has a value of 15 μ

m or larger, and

wherein an interval between the adjacent protrusions has a value of 200 μ

m or less.

11. The display device of claim 10, wherein:

the average of surface roughness or height differences of the protrusions has a value not more than a predetermined gap distance designed for spacing apart of the reflection sheet from the light guide plate,

the interval between the adjacent protrusions has a value not less than a maximum diameter of a majority of the particles, and

the maximum diameter of a majority of the plurality of particles is 15 μ

m or larger.

12. The display device of claim 11, further comprising:

a lower skin layer disposed on the other surface of the main body.

13. The display device of claim 11, wherein:

a part of the plurality of particles is positioned in the main body.

14. The display device of claim 10, wherein:

the main body has reflection providing globules or bubbles defined therein.

15. The display device of claim 10, wherein:

the light receiving display panel comprises a liquid crystal layer.

16. A method of manufacturing a reflection sheet, comprising:

disposing a first material to be used for forming an upper skin layer comprising a plurality of particles at one side of a second material to be used for forming a main body of the reflection sheet and coextruding the first and second materials;

stretching the coextruded material;

providing gas to the stretched material; and

foaming the stretched material.

17. The method of claim 16, wherein:

prior to the coextruding, a third material to be used for forming a lower skin layer is disposed at the other side of the second material for the main body of the reflection sheet and the third material is coextruded together with the first and second materials.

18. The method of claim 16, wherein:

in the foaming, bubbles are formed in the material for the main body of the reflection sheet.

19. The method of claim 18, wherein:

in the foaming, irregular protrusions are formed on a surface of the material for the upper skin layer due to the presence of the particles.

20. The method of claim 16, further comprising:

examining surface roughness of the manufactured reflection sheet,

wherein in the examining includes determining whether an average of height differences of the protrusions formed on a surface of the material for the upper skin layer has a value of 15 μ

m or larger, and whether an interval between the protrusions has a value of 200 μ

m or less.