Abstract:
A compound optical film comprises an unitary two-layer structure consisting of a light guide layer and a light reflective layer attached on the light guide layer. A plurality of light scattering particles are dispersed in the light guide layer adjacent to an interface between the light guide layer and the light reflective layer. The compound optical film can reduce the thickness of backlight module while the compound optical film is used in backlight module. The present art also relates to a manufacturing method for the compound optical film.

Description:
[0001]    BACKGROUND 
         [0002]    1. Technical Field 
         [0003]    The present disclosure relates to a compound optical film and a method for manufacturing the same. 
         [0004]    2. Description of Related Art 
         [0005]    Optical films used in a backlight module include a light guide plate, a reflective plate, and a light diffusion plate. As the backlight module becomes thinner, the thickness of the optical films used in the backlight module must be designed smaller to satisfy the demand of the thinner backlight module. Usually, these optical films are separately produced and then assembled into the backlight module layer by layer. However, these manufacturing and assembly methods of the optical films not only need complex steps and may induce more defective produces, but also do not help to reduce the thickness of the backlight module. 
         [0006]    Therefore, a compound optical film and a method for manufacturing the same, which can overcome the above-mentioned problems, is needed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a schematic view of a compound optical film according to a first embodiment. 
           [0008]      FIG. 2  is a schematic view of a manufacturing method of the compound optical film of  FIG. 1  according to a second embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0009]    Referring to  FIG. 1 , a compound optical film  100 , according to the first embodiment, is used in a backlight module. The compound optical film  100  includes a light guide layer  10 , a light reflective layer  20 , and light scattering particles  30 . 
         [0010]    The light guide layer  10  includes a light incident surface  11 , a light emitting surface  12 , and a first contact surface  13 . The light emitting surface  12  adjoins to the light incident surface  11 . The first contact surface  13  faces the light emitting surface  12  and adjoins the light incident surface  11 . 
         [0011]    The light guide layer  10  is made of a light-permeable material, which is usually used to make light guide plates, such as PMMA (Polymethyl Methacrylate), COP (Cocio Olefines Polymers), and PC (Polycarbonate). In the embodiment, the light guide layer  10  is comprised of PMMA. 
         [0012]    The light reflective layer  20  includes a second contact surface  21  and a bottom surface  22  opposite to the second contact surface  21 . The second contact surface  21  is corresponding with the first contact surface  13  of the light guide layer  10 . The light reflective layer  20  and the light guide layer  10  are laminated together to form a whole body in a manner that the first contact surface  13  and the second contact surface  21  are adhered to each other. The light reflective layer  20  is made of high-reflectance materials. In present embodiment, the light reflective layer  20  is comprised of PET(polyethylene terephthalate). Light is transmitted into the light guide layer  10  from the light incident surface  11 , then is reflected by the light reflective layer  20 , and finally exits out of the light guide layer  10  from the light emitting surface  12 . 
         [0013]    In another embodiment, the light striking on the light reflective layer  20  may partly enter into the light reflective layer  20  from the second contact surface  21  and emit out of the light reflective layer  20  from the bottom surface  22 . A reflective coating (not shown) can be formed on the bottom surface  22  of the light reflective layer  20  to avoid the light emitting out of the light reflective layer  20  from the bottom surface  22 . 
         [0014]    The light scattering particles  30  are dispersed in the light guide layer  10  and arranged on the second contact surface  21 . The light scattering particles  30  are used to scatter light striking on the second contact surface  21  to make the brightness of the light emitting from the light emitting surface  12  become more uniform. 
         [0015]    A distribution density of the light scattering particles  30  on the second contact surface  21  may be uniform or non-uniform according to different design requirements. In the present embodiment, a distribution density of the light scattering particles  30  gradually increases along a direction away from the light incident surface  11 . In this situation, the brightness of the light emitting from the light emitting surface  12  can be more uniform. 
         [0016]    When the compound optical film  100  is used in the backlight module, the light guide layer  10  can be instead of the prior light guide plate, the light reflective layer  20  can be instead of the prior light reflective plate. Additionally, the light scattering particles  30  dispersed in the light guide layer  10  can also play the role of a prior light diffusion plate. With above-mentioned compound structure, the compound optical film  100  has triple functions of guiding light, reflecting light, and diffusing light. Comparing with the prior light guide plate and light reflective plate separately assembled in backlight module, the unitary structure of the compound optical film  100  can avoid a gap forming between the light guide layer and the light reflective layer and is helpful to reduce the thickness of the backlight module. 
         [0017]    Referring to  FIG. 2 , a method for manufacturing the compound optical film  100 , according to a second embodiment, includes following steps. 
         [0018]    Firstly, a light reflective film  60  is provided. The light reflective  60  includes a second contact surface  61  and a bottom surface  62  opposite to the second contact surface  61 . In an alternative embodiment, a reflective coating can be formed on the bottom surface  62 . 
         [0019]    Secondly, a plurality of light scattering particles  70  are formed on the second contact surface  61 . In the present embodiment, the light scattering particles  70  are formed on the second contact surface  61  by roller-printing method described as follows. Ink containing particles with high reflectivity, such as TiO2, Ba5O4 etc, is provided. The ink is printed on the second contact surface  61 , and finally the ink is dried to form the light scattering particles  70  on the second contact surface  61 . The distribution density of the light scattering particles  70  on the second contact surface  61  may be uniform or non-uniform according to different design. In the present embodiment, the distribution density of the light scattering particles  70  in the second contact surface  61  is gradually bigger or smaller from one side to an opposite side of the second contact surface  61 . 
         [0020]    Thirdly, a mold  80  including a molding cavity  81  is provided. The light reflective film  60  with light scattering particles  70  on the second contact surface  61  is placed into the molding cavity  81 . The bottom surface  62  is attached on the inner wall of the molding cavity  81  and the second contact surface  61  and the light scattering particles  70  are exposed in the molding cavity  81 . 
         [0021]    Finally, light-permeable material is introduced into the molding cavity  81  to cover the second contact surface  61  and the light scattering particles  70 , thereby a light guide layer  90  is formed on the second contact surface  61 . 
         [0022]    By the above-motioned manufacturing method, the compound optical film  100  having triple functions of guiding light, reflecting light, and diffusing light can be obtained. When the compound optical film  100  is used in the backlight module, one piece of the compound optical film  100  can be instead of three pieces optical film including the light guide plate, light reflective plate and light diffusing plate previously used in the backlight module. This can greatly simplify the assemble steps of the backlight module and help to reduce the thickness of the backlight module. 
         [0023]    It is to be understood, however, that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.