Abstract:
A composite light guide plate manufacturing method includes the steps of providing a light guide substrate; providing a transfer membrane, which sequentially includes a substrate, a reflective layer and a diffusion microstructure; attaching the transfer membrane to the light guide substrate with a side of the transfer membrane, which has the diffusion microstructure thereon; and removing the substrate to expose the reflective layer.

Description:
RELATED APPLICATIONS 
       [0001]    The present application is based on, and claims priority from, U.S. Provisional Application Ser. No. 61/720,995, filed on Oct. 31, 2012, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     
    
     BACKGROUND 
       [0002]    1. Field of Invention 
         [0003]    The present invention relates to a composite light guide plate manufacturing method. 
         [0004]    2. Description of Related Art 
         [0005]    The Taiwan patent application (No. TW201224541) discloses a conventional backlight module. Referring to  FIG. 1 , it illustrates an enlarged cross-sectional view of a conventional backlight module. The backlight module includes a light guide module  100  and a light source  106 . The light guide module  100  includes a light guide plate  102  and a diffusion reflection sheet  104 . The light source  106  is located on a lateral edge of the light guide plate  102  to provide incident light beams L1 into the light guide plate  102 . The diffusion reflection sheet  104  is fixed to the bottom surface  102   a  of the light guide plate  102  by means of adhesive layers  104   a.  The adhesive layers  104   a  may contain diffusion particles, mixed therein, so that the light beams L1 can generate diffusion and reflection by means of the diffusion particles, thereby enabling the light guide plate  102  to output light beams uniformly. 
         [0006]    However, the current portable electronic products are all designed with thin profiles, such that the conventional light guide module encountered the difficulties on the reduction of the thickness when thin-profile electronic products are manufactured. 
       SUMMARY 
       [0007]    It is therefore an objective of the present invention to provide a composite light guide plate manufacturing method in order to reduce an overall thickness of a backlight module. 
         [0008]    In accordance with the foregoing and other objectives of the present invention, a composite light guide plate manufacturing method includes the steps of providing a light guide substrate; providing a transfer membrane, which includes sequentially includes a substrate, a reflective layer and a diffusion microstructure; attaching the transfer membrane to the light guide substrate with a side of the transfer membrane, which has the diffusion microstructure; and removing the substrate to expose the reflective layer. 
         [0009]    According to another embodiment disclosed herein, the method further includes the step of forming a light diffusion layer located on a surface of the light guide substrate, which is opposite to the reflective layer. 
         [0010]    According to another embodiment disclosed herein, the light diffusion layer is formed by coating or imprinting. 
         [0011]    According to another embodiment disclosed herein, the reflective layer is formed by printing a white ink layer or a metallic ink layer on the substrate. 
         [0012]    According to another embodiment disclosed herein, the reflective layer is a metal coating formed by electroless plating, electroplating, sputtering or vapor deposition. 
         [0013]    According to another embodiment disclosed herein, the method further includes the step of forming a releasing layer between the substrate and the reflective layer to easily separate the substrate apart from the reflective layer. 
         [0014]    According to another embodiment disclosed herein, the method further includes the step of forming an adhesive layer on the diffusion microstructure. 
         [0015]    According to another embodiment disclosed herein, the substrate is a plastic membrane, a metallic membrane or a paper membrane. 
         [0016]    According to another embodiment disclosed herein, the diffusion microstructure is an opaque white ink layer. 
         [0017]    Thus, the composite light guide plate manufacturing method has at least the following advantages: 
         [0018]    (1) The thickness of the reflective layer can be made thinner (compared with the conventional reflection sheet) by a transfer method instead, thereby reducing the overall thickness of the composite light guide plate; 
         [0019]    2) The light diffusion layer on the-emitting surface of the light guide plate can be formed by directly coating or imprinting manner, and its thickness is also thinner than a conventional independent diffusion sheet, thereby reducing the overall thickness of the composite light guide plate as well; and 
         [0020]    (3) The downsizing of the reflective layer and the diffusion layer can also decrease the materials of the reflective layer and the diffusion layer, thereby saving the material costs. 
         [0021]    It is to be understood that both the foregoing general description and the following detailed description are by examples, and are intended to provide further explanation of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    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. In the drawings, 
           [0023]      FIG. 1  illustrates an enlarged cross-sectional view of a conventional backlight module; 
           [0024]      FIGS. 2A-2C  sequentially illustrate cross-sectional views of a composite light guide plate manufacturing method according to an embodiment of this invention; and 
           [0025]      FIGS. 3A-3C  sequentially illustrate cross-sectional views of a composite light guide plate manufacturing method according to another embodiment of this invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0026]    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. 
         [0027]    The present invention provides a composite light guide plate manufacturing method to manufacture a light guide plate within a backlight module of a thin-profile portable electronic product.  FIGS. 2A-2C  sequentially illustrate cross-sectional views of a composite light guide plate manufacturing method according to an embodiment of this invention. A light guide substrate  212  is provided with a light diffusion layer  214 , but not being limited to, formed on a light-emitting surface  212   a  of the light guide substrate  212 . A transfer membrane  202  is provided to sequentially include a substrate  204 , a reflective layer  206  and multiple diffusion microstructures  208 . The transfer membrane  202  is used to “transfer” the reflective layer  206  and multiple diffusion microstructures  208  to the light guide substrate  212  so as to achieve a thin-profile composite light guide plate. Referring to  FIG. 2B , the transfer membrane  202  is attached to the light guide substrate  212  with its side, which has the diffusion microstructure  208 , e.g. by heating or pressing the transfer membrane  202  to the light guide substrate  212 . In particular, the transfer membrane  202  is attached to a surface  212   c  of the light guide substrate  212  to which the light-emitting surface  212   a  is opposite. The substrate  204  is then removed to expose the reflective layer  206  (as illustrated in  FIG. 2B ) so as to achieve a composite light guide plate  200  (as illustrated in  FIG. 2C ). In this embodiment, the light diffusion layer  214  is located on a surface (i.e., the light-emitting surface  212   a ) of the light guide substrate  212 , which is opposite to the reflective layer  206 . 
         [0028]    The light diffusion layer  214  can be formed by, but not being limited to, coating or imprinting (e.g., heat imprinting). The substrate  204  of the transfer membrane  202  can be a plastic membrane, a metallic membrane, a paper membrane or other applicable membranes. In an embodiment, the reflective layer  206  of the transfer membrane  202  is formed by, but not being limited to, printing a white ink layer or a metallic ink layer on the substrate  204 . in another embodiment, the reflective layer  206  of the transfer membrane  202  can be a metal coating formed by, but not being limited to, electroless plating, electroplating, sputtering or vapor deposition. No matter how the reflective layer  206  is made, e.g., electroless plating, electroplating, sputtering or vapor deposition, the reflective layer  206  can be made thinner (compared with the conventional reflective layer) because the reflective layer  206  is coated on the substrate  204 , which serves as a support base. When the reflective layer  206  of the transfer membrane  202  is “transferred” to the light guide substrate  212  to form a composite light guide plate  200 , its overall thickness is a little bit thicker than the light guide substrate  212 , thereby maintain the composite light guide plate  200  as a thin profile. In addition, the diffusion microstructures  208  are opaque white ink layers on the reflective layer  206 . In this embodiment, the diffusion microstructures  208  may contain, but not being limited to, diffusion particles  208   a  mixed therein. 
         [0029]    Referring to  FIG. 2C , it illustrates a finished composite light guide plate. When the composite light guide plate  200  serves as part of the back-light module of the portable electronic device, the light beams are input through the light-receiving surface  212   b  of the light guide substrate  212 , and then reflected by the reflective layer  206  or the diffusion microstructures  208 , and finally output through the light-emitting surface  212   a  of the light guide substrate  212  (it without the light diffusion layer  214 ), or finally output through the light diffusion layer  214  uniformly. 
         [0030]      FIGS. 3A-3C  sequentially illustrate cross-sectional views of a composite light guide plate manufacturing method according to another embodiment of this invention. The embodiment of  FIGS. 3A-3C  is different from the embodiment of  FIGS. 2A-2C  in a different transfer membrane. 
         [0031]    A light guide substrate  212  is provided with a light diffusion layer  414 , but not being limited to formed on a light-emitting surface  212   a  of the light guide substrate  212 . A transfer membrane  202 ′ is provided to sequentially include a substrate  204 , a releasing layer  205 , a reflective layer  206  and multiple diffusion microstructures  208 . The transfer membrane  202 ′ is used to “transfer” the reflective layer, the reflective layer and multiple diffusion microstructures  208  to the light guide substrate  212  so as to achieve a thin-profile composite light guide plate. Referring to  FIG. 3B , the transfer membrane  202 ′ is attached to the light guide substrate  212  with its side, which has the diffusion microstructure  208 , e.g. by heating or pressing the transfer membrane  202 ′ to the light guide substrate. In particular, the transfer membrane  202 ′ is attached to a surface  212   c  of the light guide substrate  212  to which the light-emitting surface  2 I 2   a  is opposite. The substrate  204  is then removed to expose the reflective layer  206  (as illustrated in  FIG. 3B ) so as to achieve a composite light guide plate  200  (as illustrated in  FIG. 3C ). In this embodiment, the light diffusion layer  214  is located on a surface (i.e., the light-emitting surface  212   a ) of the light guide substrate  212 , which is opposite to the reflective layer  206 . 
         [0032]    In this embodiment, a releasing layer  205  is added between the substrate  204  and the reflective layer  206  of the transfer membrane  202 ′ so as to easily separate substrate  204  apart from the reflective layer  206  and not to damage the reflective layer  206 . 
         [0033]    Moreover, adhesive layers  209  may be further formed on those diffusion microstructures  208  before the transfer membrane  202 ′ is attached to the light guide substrate  212 . Therefore, after the transfer membrane  202 ′ is attached to the light guide substrate  212 , the diffusion microstructures  208  can be reliably attached to the light guide substrate  212 . 
         [0034]    The light diffusion layer  214  can be formed by, but not being limited to, coating or imprinting (e.g., heat imprinting). The substrate  204  of the transfer membrane  202 ′ can be a plastic membrane, a metallic membrane, a paper membrane or other applicable membranes. In an embodiment, the reflective layer  206  of the transfer membrane  202 ′ is formed by, but not being limited to printing a white ink layer or a metallic ink layer on the substrate  204 . In another embodiment, the reflective layer  206  of the transfer membrane  202 ′ can be a metal coating formed by, but not being limited to, electroless plating, electroplating, sputtering or vapor deposition. No matter how the reflective layer  206  is made, e.g., electroless plating, electroplating, sputtering or vapor deposition, the reflective layer  206  can be made thinner (compared with the conventional reflective layer) because the reflective layer  206  is coated on the substrate  204 , which serves as a support base. When the reflective layer  206  of the transfer membrane  202 ′ is “transferred” to the light guide substrate  212  to form a composite light guide plate  200 , its combination thickness is a little bit thicker than the light guide substrate  212 , thereby maintaining the composite light guide plate  200  as a thin profile. In addition the diffusion microstructures  208  are opaque white ink layers of the reflective layer  206 . In this embodiment, the diffusion microstructure  208  may contain, but not being limited to, diffusion particles  208   a  mixed therein. 
         [0035]    Referring to  FIG. 3C , it illustrates a finished composite light guide plate. When the composite light guide plate  200  serves as part of the back-light module of the portable electronic device, the light beams are input through the light-receiving surface  212   b  of the light guide substrate  212 , and then reflected by the reflective layer  206  or the diffusion microstructures  208 , and finally output through the light-emitting surface  212   a  of the light guide substrate  212  (if without the light diffusion layer  214 ), or finally output through the light diffusion layer  214  uniformly. 
         [0036]    According to the above-discussed embodiments of the present invention, the composite light guide plate manufacturing method has at least the following advantages: 
         [0037]    (1) The thickness of the reflective layer can be made thinner (compared with the conventional reflection sheet) by a transfer method instead, thereby reducing the overall thickness of the composite light guide plate; 
         [0038]    (2) The light diffusion layer on the-emitting surface of the light guide plate can be formed by directly coating or imprinting manner, and its thickness is also thinner than a conventional independent diffusion sheet, thereby reducing the overall thickness of the composite light guide plate as well; and 
         [0039]    (3) The downsizing of the reflective layer and the diffusion layer can also decrease the materials of the reflective layer and the diffusion layer, thereby saving the material costs. 
         [0040]    It will be apparent w 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.