This application claims the priority benefit of Taiwan application serial no. 96115632, filed May 2, 2007. All disclosure of the Taiwan application is incorporated herein by reference.
1. Field of the Invention
The present invention generally relates to an optical film and a light source module using the same, in particular, to a diffusing polarizer and a backlight module using the same.
2. Description of Related Art
As electronic industries being rapidly developed, flat panel displays have taken in place of the cathode ray tube (CRT) displays in the market and become a mainstream therein. Among several kinds of typical flat panel displays, liquid crystal displays (LCD) are most well-developed and popular. Since LCD panels do not emit light by themselves, backlight modules are usually provided under the LCD panels for providing a light source for displaying.
Conventional optical films usually include a diffusing plate and a brightness enhancement film (BEF). The diffusing plate is adapted for evening incident light beams, and the brightness enhancement film is adapted for concentrating the light beams so as to improve on-axial brightness of the light source.
Further, a typical brightness enhancement film may be featured as having birefringence. Such a brightness enhancement film is adapted to allow incident light beams having a specific polarizing direction passing therethrough, while reflecting light beams having other polarizing direction for reusing. In such a way, more light beams can be guided into the LCD panel. However, conventional brightness enhancement films are configured by alternately stacking a plurality of materials of different refractive indices to obtain birefringence. Unfortunately, the thickness and the manufacturing process of such a brightness enhancement film configured by a plurality of film layers cause high cost. Further, when the light beams passing through interfaces between different material layers of the film stack, a loss of the light beams occur, so that the efficiency of the light sources is decreased. Additionally, the production yield rate of the brightness enhancement film configured by the plurality of film layers is accordingly limited.
Accordingly, the present invention is directed to diffusing polarizer for polarizing and evening incident light beams.
The present invention is also directed to a backlight module using the foregoing diffusing polarizer.
The present invention provides diffusing polarizer. The diffusing polarizer includes a substrate, and a microstructure layer. The microstructure layer is disposed on the substrate. The microstructure layer includes a solid-phase liquid crystal material having a birefringence feature.
The present invention further provides a backlight module. The backlight module includes a plane light source structure and a diffusing polarizer. The plane light source structure has an output surface. The diffusing polarizer is disposed upon the output surface of the plane light source structure. The diffusing polarizer includes a substrate, and a microstructure layer. The microstructure layer is disposed on the substrate. The microstructure layer includes a solid phase liquid crystal material having a birefringence feature.
The diffusing polarizer according to the present invention uses a birefringent solid phase liquid crystal material such that the birefringence of the diffusing polarizer can be achieved without requiring multi-layer structure as the prior art of aforesaid brightness enhancement film. When such a diffusing polarizer is used in a backlight module, the number, thickness and weight of the optical films used in the backlight module can be reduced.
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
The solid-phase liquid crystal material 222 of the diffusing polarizer 200 is featured in birefringence. Therefore, the diffusing polarizer 200 allows light beams having a specific polarizing direction passing therethrough, while reflecting light beams having other polarizing directions. In such a way, the diffusing polarizer 200 has a function of polarizing light beams incident thereto. In this manner, only one piece of diffusing polarizer 200 of the present invention can achieve functionalities of a reflective polarizer and a diffuser.
However, the protrusions 224 are not necessarily limited to be strip shaped.
It should be noted that diffusing particles as disclosed in the foregoing embodiments (shown in
The present invention also provides a backlight module using the foregoing described diffusing polarizer.
According to an aspect of the embodiment, the plane light source 310 is a direct type light source including a plurality of light emitting devices 312, and a reflector 314, for example. The light emitting devices 312 are disposed in the reflector 314. According to another aspect of the embodiment, the plane light source 310 for example is an edge type light source.
In summary, because the solid-phase liquid crystal material of the diffusing polarizer is featured in birefringence, it allows incident light beams having a specific polarizing direction passing therethrough, while reflecting light beams having other polarizing directions. Therefore, the diffusing polarizer is adapted for polarizing light beams incident thereto. The diffusing polarizer reflects incident light beams randomly, so that it can uniform the reflected light beams. Further, the microstructure layer includes a plurality of protrusions, by which the diffusing polarizer is adapted for concentrating light beams. When such a diffusing polarizer is used for a backlight module, only one piece of diffusing polarizer of the present invention can achieve functionalities of a reflective polarizer and a diffuser.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.
Number | Date | Country | Kind |
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96115632 | May 2007 | TW | national |