Light guide plate and backlight unit comprising same

• US 10,082,617 B2
• Filed: 09/25/2015
• Issued: 09/25/2018
• Est. Priority Date: 09/30/2014
• Status: Active Grant

• Current Assignee: Kolon Industries Incorporated
• Original Assignee: Kolon Industries Incorporated
• Inventors: Kim, Min Jeong, Kim, Kyoung Hwa, Shim, Sang Hwa, Cho, Chun Sung
• Primary Examiner(s): Guharay, Karabi
• Application Number:
  US15/513,240
• Publication Number:
  US 20170307806A1
• Time in Patent Office: 1,096 Days
• CPC Class Codes: G02B 6/0015 provided on the surface of the light guide or in the bulk of it
• CPC Class Codes: G02B 6/003 Lens or lenticular sheet or layer
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/0065 Manufacturing aspects; Material aspects
• CPC Class Codes: G02F 1/133602 Direct backlight

Abstract

This invention relates to a light guide plate and a backlight unit including the same, and more particularly to a light guide plate, which is configured such that a surface layer having desired optical properties and hardness is provided in the form of a thin film on one surface of a substrate layer having excellent optical properties and exhibiting dimensional stability regardless of an external environment, thus manifesting superior processability and scratch resistance and minimizing luminance degradation, and to a backlight unit including the same.

Claims

1. A light guide plate, comprising:

a substrate layer including, as a main component, a resin having a light transmittance of at least 90%, a refractive index of 1.47 to 1.59, and a water absorption rate of less than 0.30%; and

a surface layer formed on a lower surface of the substrate layer and composed mainly of a resin having a refractive index difference of 0.05 or less and a hardness increased by at least 1 H compared to the main component resin of the substrate layer with a light transmittance of at least 90%,

wherein the light guide plate has a plurality of engraved patterns which are formed in a shape that penetrates up to a predetermined thickness of the substrate layer through the surface layer.

2. The light guide plate of claim 1, wherein the surface layer has a thickness corresponding to 1 to 5% of a total thickness of the light guide plate.

3. The light guide plate of claim 2, which is manufactured using a co-extrusion process.

4. The light guide plate of claim 2, each of the engraved patterns forms a semicircular groove.

5. The light guide plate of claim 1, wherein the surface layer has a thickness ranging from 30 μ

m to 150 μ

m.

6. The light guide plate of claim 5, which is manufactured using a co-extrusion process.

7. The light guide plate of claim 5, which is manufactured each of the engraved patterns forms a semicircular groove.

8. The light guide plate of claim 1, wherein the plurality of engraved patterns is formed in a shape that penetrates up to a thickness corresponding to 0.1 to 10% of a total thickness of the substrate layer.

9. The light guide plate of claim 1, wherein the plurality of engraved patterns has a longitudinal cross-section having a shape selected from the group consisting of a semicircular shape, a triangular shape, a rectangular shape, and an irregular shape.

10. The light guide plate of claim 1, which is manufactured using a co-extrusion process.

11. The light guide plate of claim 10, wherein the co-extrusion process is performed in a manner in which respective resins of the substrate layer and the surface layer are hot-melted into fluids using an extruder, and are simultaneously melt-discharged using a feed block, extruded via a T-die, and continuously pressed, so that a thickness uniformity of the surface layer satisfies 20% or less.

12. The light guide plate of claim 1, wherein the substrate layer is composed mainly of a resin selected from the group consisting of a polycarbonate-based resin, a polystyrene-based resin, an acrylic resin, an olefin-based resin, a polyester-based resin and a polyamide-based resin, a copolymer thereof, a mixture thereof, and a derivative thereof.

13. The light guide plate of claim 1, wherein the surface layer is composed mainly of a resin selected from the group consisting of a polycarbonate-based resin, a polystyrene-based resin, an acrylic resin, an olefin-based resin, a polyester-based resin and a polyamide-based resin, a copolymer thereof, a mixture thereof, and a derivative thereof.

14. The light guide plate of claim 1, wherein the substrate layer is composed mainly of a copolymer including 60 wt % or less of methyl methacrylate.

15. The light guide plate of claim 1, wherein the surface layer is composed mainly of a polymethyl methacrylate resin or a copolymer including at least 70 wt % of or methyl methacrylate.

16. The light guide plate of claim 1, wherein the substrate layer comprises a methyl methacrylate-styrene resin, and the surface layer comprises a polymethyl methacrylate resin.

17. A backlight unit, comprising the light guide plate of claim 1.