# US 7,744,245 B2 · Prism sheet and backlight module using the same

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- Number: US 7,744,245 B2
- Document ID: US7744245B2
- Status: Granted
- Kind: B2
- Application number: 11/940,328
- Filed: 2007-11-15
- Published: 2009-03-26
- Granted: 2010-06-29
- Earliest claimed: 2007-09-21
- Assignees: Hon Hai Precision Industry Co., Ltd.
- Inventors: Tung-Ming Hsu; Shao-Han Chang
- Web page: https://patentgrep.com/patent/US7744245B2

## CPC

- G02B 5/045: {Prism arrays}
- G02F 1/133606: {including a specially adapted diffusing, scattering or light controlling members}
- G02F 1/133607: {the light controlling member including light directing or refracting elements, e.g. prisms or lenses}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS

## Abstract

An exemplary prism sheet includes a transparent main body. The main body includes a first surface, a second surface and a plurality of conical frustum micro-depressions and a plurality of triangular pyramidal micro-depressions. The first surface and the second surface are on opposite sides of the main body. The conical frustum micro-depressions are formed in the first surface and the triangular pyramidal micro-depressions are formed in the second surfaces. A backlight module using the present prism sheet is also provided.

## Claims

### Claim 1

A backlight module comprising:
a plurality of lamps;
a light diffusion plate disposed above the lamps; and
a prism sheet disposed on the light diffusion plate, the prism sheet includes a transparent main body having
a first surface,
a second surface opposite to the first surface, and
a plurality of conical frustum micro-depressions formed in the first surface, and
a plurality of triangular pyramidal micro-depressions formed in the second surface, wherein the triangular pyramidal micro-depressions are formed arranged on the second surface side by side, and each of the triangular pyramidal micro-depressions is surrounded by three adjacent triangular pyramidal micro-depressions.

### Claim 2 (depends on 1)

The backlight module according to claim 1, wherein a pitch between centers of adjacent triangular pyramidal micro-depressions is in a range from about 0.025 millimeters to about 1 millimeter.

### Claim 3 (depends on 1)

The backlight module according to claim 1, wherein a vertex angle of ridges defined by adjacent triangular pyramidal micro-depressions is in a range from about 50 degrees to about 120 degrees.

### Claim 4 (depends on 1)

The backlight module according to claim 1, wherein a thickness of the prism sheet is in a range from about 0.5 millimeters to about 3 millimeters.

### Claim 5 (depends on 1)

The backlight module according to claim 1, wherein an inclined angle of the slope of each conical frustum micro-depressions is in a range from about 30 degrees to about 75 degrees.

### Claim 6 (depends on 1)

The backlight module according to claim 1, wherein a radius of top end of each conical frustum micro-depression is in a range from about 0.00625 millimeters to about 1.5 millimeters.