This Non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 096130162 filed in Taiwan, Republic of China on Aug. 15, 2007, the entire contents of which are hereby incorporated by reference.
1. Field of Invention
The invention relates to a backlight module and an optical film thereof that are capable of enhancing brightness in two axial directions.
2. Related Art
With the coming of the digital age, the technology of a flat panel display also grows rapidly and the flat panel display has become one of the indispensable electronic products. Thus, the requirements on the technology and the function of the flat panel display are also increased.
The flat panel display mainly includes a flat display panel and a backlight module. The flat display panel mainly has a color filtering substrate, a thin-film transistor (TFT) substrate and a liquid crystal layer interposed between the color filtering substrate and the TFT substrate. The backlight module serves as a backlight source for uniformly distributing the light, coming from a light source, over a surface of a liquid crystal panel. Conventionally, a cold cathode fluorescent lamp (CCFL) serves as the light source of the backlight module, and the backlight modules can be classified into direct type backlight modules and side-edge backlight modules according to the arrangement of the light source. Recently, in order to enhance the brightness visual effect of the flat panel display, the angle of emission of the light passing through a brightness enhancement film has to be decreased to the angle within ±30 or ±40 degrees. Therefore, enhancing the function of the brightness enhancement film of the backlight module has become one of the indispensable technologies of the backlight module.
Referring to
The brightness enhancement film 12 can refract the incident light L1 into output light with small angles so that the angle of emission of most light L1 can be decreased to fall within ±30 or ±40 degrees and the observer within ±30 or ±40 degrees of the optical axis can have the stronger brightness visual effect. Referring again to
However, using two brightness enhancement films 12 not only increases the cost but also decreases the transmission rate.
Therefore, it is necessary to provide a backlight module and an optical film thereof, in which brightness enhancing effects in two axial directions can be both reached, the cost can be reduced and the transmission rate can be enhanced.
In view of the foregoing, the invention is to provide a backlight module and an optical film thereof, in which brightness enhancing effects in two axial directions can be both reached, the cost can be reduced and the transmission rate can be enhanced.
To achieve the above, the invention discloses an optical film including a substrate and at least one pyramid-like structure. The pyramid-like structure is disposed on a first surface of the substrate. The pyramid-like structure has a base, a first face, a second face and a third face. The first, second and third faces are connected together and disposed along the base. At least one of the first, second and third faces relative to the base forms an included angle smaller than 90 degrees.
In addition, the invention also discloses a backlight module including a light source and an optical film. The light source is for emitting light. The optical film is disposed on an optical path of the light and includes a substrate and at least one pyramid-like structure. The pyramid-like structure is disposed on a first surface of the substrate and has a base, a first face, a second face and a third face. The first, second and third faces are connected together and disposed along the base. At least one of the first, second and third faces relative to the base forms an included angle smaller than 90 degrees.
As mentioned above, the backlight module and the optical film thereof according to the invention have the following features. First, the optical film is disposed on the optical path of the light emitted from the light source, and is disposed on the base through each pyramid-like structure of the optical film. In addition, at least one of the first, second and third faces connected together in the pyramid-like structure forms an included angle smaller than 90 degrees relative to the base. Compared with the prior art, the invention only uses a single optical film, which has the pyramid-like structure disposed on the substrate. Accordingly, the cost can be decreased, and the first, second and third faces of the pyramid-like structure can cooperate with one another so that the brightness enhancement effects in the two axial directions can be achieved when the light passes through the pyramid-like structure. Furthermore, it is possible to prevent the transmission rate of the light from being decreased.
The invention will become more fully understood from the detailed description and accompanying drawings, which are given for illustration only, and thus are not limitative of the present invention, and wherein:
The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements.
Referring to
In this embodiment, the first diffuser plate 23 is disposed on one side of the optical film 22, and the light guide plate 24 is disposed on the other side of the optical film 22. The light source 21 is disposed adjacent to the light guide plate 24, and the light source 21 emits light L2 to the light guide plate 24. The light L2 travels to the optical film 22 through the light guide plate 24.
Each pyramid-like structure 222 is disposed on one surface of the substrate 221 and has a base B01, a first face S01, a second face S02 and a third face 803. The base B01 has a first edge S11, a second edge S12 and a third edge S13 connected together, as shown in
That is, the first face S01, the second face S02 and the third face S03 are respectively connected with the first edge S11, the second edge S12 and the third edge S13. At least one of the first face S01, the second face S02 and the third face S03 forms an included angle θ relative to the base B01, and the included angle α is smaller than 90 degrees. For example, each of the first face S01, the second face S02 and the third face S03 forms the included angle θ smaller than 90 degrees relative to the base B01, as shown in
In this embodiment, the shape of the base B01 can be implemented as a triangle, and the lengths of the first edge S11, the second edge S12 and the third edge S13 of the base B01 substantially are greater than 10 μm, and preferably range from 10 μm to 100 μm and are substantially the same in the example when the base B01 is a regular triangle. Alternatively, the first edge S11, the second edge S12 and the third edge S13 are substantially different from one another. Of course, two of the lengths of the first edge S11, the second edge S12 and the third edge S13 of the base B01 may be substantially the same in the example when the base B01 is an equilateral triangle. In addition, each of the first face S01, the second face S02 and the third face S03 of the pyramid-like structure 222 has a triangle-like shape, a right triangle shape or an equilateral triangle shape. The pyramid height h of the pyramid-like structure 222 is the same as or different from the lengths of the first edge S11, the second edge 812 and the third edge S13.
In addition, referring to
In addition,
In practice, the substrate 221 and each pyramid-like structure 222 can be integrally formed or adhered together. Herein, the substrate 221 and each pyramid-like structure 222 are integrally formed as a single unit. In addition, the manufacturing method of the pyramid-like structure 222 is not particularly restricted. The pyramid-like structure 222 can be formed on the substrate 221 by soft pressing, hot pressing, hot rolling or ultra-violet ray solidification, or by photolithographic processing, electroforming, molding or precise micro-processing in the micro-electro-mechanical-system technology.
In addition, referring to
As shown in
The backlight module 2 of this embodiment only needs one single optical film 22, and the first face S01, the second face S02 and the third face S03 of the pyramid-like structure 222 cooperate with one another so that when passing through the pyramid-like structure 222, the brightness enhancement effects of the light L2 in the vertical direction and the horizontal direction can be achieved and the cost can be reduced, and it is possible to prevent the light transmission rate from being decreased.
Referring to
In addition, the first diffuser plate 33 is disposed on one side of the optical film 32, and the second diffuser plate 34 is disposed on the other side of the optical film 32. The light source emits light and is disposed opposite to the optical film and disposed on one side of the second diffuser plate 34. Herein, the backlight module 3 of this embodiment is a direct type backlight module.
In summary, the backlight module and the optical film thereof according to the invention have the following features. First, the optical film is disposed on the optical path of the light; emitted from the light source, and is disposed on the base through each pyramid-like structure of the optical film. In addition, at least one of the first, second and third faces connected together in the pyramid-like structure forms an included angle smaller than 90 degrees relative to the base. Compared with the prior art, the invention only uses a single optical film, which has the pyramid-like structure disposed on the substrate. Accordingly, the cost can be decreased, and the first, second and third faces of the pyramid-like structure can cooperate with one another so that the brightness enhancement effects in the two axial directions can be achieved when the light passes through the pyramid-like structure. Furthermore, it is possible to prevent the transmission rate of the light from being decreased.
Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments, will be apparent to persons skilled in the art. It is, therefore, contemplated that the appended claims will cover all modifications that fall within the true scope of the invention.
Number | Date | Country | Kind |
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096130162 | Aug 2007 | TW | national |