# US 9,435,932 B2 · Light guide plate, method of manufacturing same, and backlight module having same

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- Number: US 9,435,932 B2
- Document ID: US9435932B2
- Status: Granted
- Kind: B2
- Application number: 13/949,250
- Filed: 2013-07-24
- Published: 2014-12-25
- Granted: 2016-09-06
- Earliest claimed: 2013-06-21
- Assignees: Hon Hai Precision Industry Co., Ltd.
- Applicants: Hon Hai Precision Industry Co., Ltd.
- Inventors: Chih-Chen Lai
- Web page: https://patentgrep.com/patent/US9435932B2

## CPC

- G02B 6/0043: {provided on the surface of the light guide}
- G02B 6/0036: {2-D arrangement of prisms, protrusions, indentations or roughened surfaces}
- G02B 6/0051: {Diffusing sheet or layer}
- G02B 6/0065: {Manufacturing aspects; Material aspects}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A light guide plate includes a main body including a light emitting surface. A number of glues, each with a different, and lower, refractive index when cured, are applied through a covering plate onto the light emitting surface. Each type of glue forms a layer on the layer below, the stack of layers forms a plurality of spaced micro-rods on the light emitting surface. Each layer in the micro-rod thus includes top and bottom and side surfaces. The different refraction indexes of each layer, reducing along a direction from the light emitting surface to the top surface of each rod, causes light to be emitted substantially equally from the periphery of each layer in the micro-rod as well as from the top of each rod. The maximum refraction index of any layer in the micro-rod is not greater than that of the main body.

## Claims

### Claim 1

A light guide plate comprising:
a main body comprising a light emitting surface; and
a plurality of spaced micro-rods on the light emitting surface, each of the micro-rods comprising a top surface on its distal end and a side surface connecting the top surface to the light emitting surface, and comprising a number of layers arranged in an order from the light emitting surface to the top surface, a refraction index of each layer being smaller than a refraction index of previous layer along the direction from the light emitting surface to the top surface, a maximum refraction index of each of the micro-rods being not greater than a refraction index of the main body, each of the micro-rods comprising the first layer, a second layer, a third layer, and a fourth layer.

### Claim 2 (depends on 1)

The light guide plate of claim 1, wherein each of the micro-rods comprises a first layer directly formed on the light emitting surface, and a refraction index of the first layer is equal to the refraction index of the main body.

### Claim 3 (depends on 1)

The light guide plate of claim 1, wherein the main body comprises a bottom surface opposite to the light emitting surface.

### Claim 4

A backlight module comprising:
a light guide plate comprising:
a main body comprising a light emitting surface, a bottom surface opposite to the light emitting surface, and a light incident surface connecting the light emitting surface to the bottom surface; and
a plurality of spaced micro-rods on the light emitting surface, each of the micro-rods comprising a top surface on its distal end and a side surface connecting the top surface to the light emitting surface, and comprising a number of layers arranged in an order from the light emitting surface to the top surface, a refraction index of each layer being smaller than a refraction index of previous layer along the direction from the light emitting surface to the top surface, a maximum refraction index of each of the micro-rods being not greater than a refraction index of the main body, each of the micro-rods comprising the first layer, a second layer, a third layer, and a fourth layer;
a reflection plate adjacent to the bottom surface; and
a light source facing the light incident surface.

### Claim 5 (depends on 4)

The backlight module of claim 4, wherein each of the micro-rods comprises a first layer directly formed on the light emitting surface, and a refraction index of the first layer is equal to the refraction index of the main body.

### Claim 6

A method for manufacturing a light guide plate, comprising:
providing a main body and a plate, the main body comprising a light emitting surface, the plate defining an array of holes, the plate touching the light emitting surface;
coating multiple layers of transparent glue in the holes;
curing the glue to obtain a number of micro-rods directly formed on the light emitting surface, wherein along a direction away from the light emitting surface, a refraction index of each layer of the transparent glue is smaller than a refraction index of a previous layer of the transparent glue, and a maximum refraction index of the transparent glue is not greater than a refraction index of the main body; and
removing the plate to obtain the light guide plate.