Abstract:
A composite-metal-composite sandwich structure is employed as a housing of a mobile electronic device. A metal sheet is preformed as a desired shape with nuts deposed thereon. A composite sheet is attached to each side of the metal sheet, exposing the nuts such that other components of the mobile electronic device can be screwed on the sandwich structure.

Description:
RELATED APPLICATIONS  
       [0001]     The present application is based on, and claims priority from, Taiwan Application Serial Number 94142827, filed Dec. 5, 2005, 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 housing structure. More particularly, the present invention relates to a housing structure of a mobile electronic device.  
         [0004]     2. Description of Related Art  
         [0005]     The plastic housing of a mobile electronic device must protect components inside itself while not encumbering the device beyond an easily-portable weight. Therefore, plastic housings are typically made of lightweight yet mechanically strong materials. To provide greater strength, plastic materials are often reinforced with carbon or glass fibers to form composite materials.  
         [0006]     The housing of a mobile electronic device usually has nuts deposed therein into which other components can be screwed. Nuts, however, cannot be easily buried into composite sheets due to their mechanical characteristics, thereby limiting applicability of composite materials as housings of mobile electronic devices.  
       SUMMARY  
       [0007]     It is therefore an objective of the present invention to provide a composite-metal-composite sandwich structure.  
         [0008]     In accordance with the foregoing and other objectives of the present invention, a composite-metal-composite sandwich structure is employed as a housing of a mobile electronic device. A metal sheet is preformed as a desired shape with nuts formed thereon. A composite sheet is attached to each side of the metal sheet, exposing the nuts such that other components of the mobile electronic device can be screwed on the sandwich structure.  
         [0009]     Thus, the sandwich structure offers high mechanical strength, low thickness and light weight due to the composite material and also provides built-in nuts by the metal material so as to overcome the prior art shortcomings. Moreover, less high-cost composite material is used by the sandwich structure to further reduce manufacturing costs as compared to a wholly composite structure.  
         [0010]     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  
       [0011]     The accompanying drawing is included to provide a further understanding of the invention and is incorporated in and constitutes a part of this specification. The drawing illustrates embodiments of the invention and, together with the description, serves to explain the principles of the invention, wherein:  
         [0012]      FIG. 1  illustrates a cross-sectional view of a composite-metal-composite sandwich structure according to one preferred embodiment of this invention.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0013]     Reference is now made in detail to the present preferred embodiments of the invention, an example of which is illustrated in the accompanying drawing. Wherever possible, the same reference numbers are used in the drawing and the description to refer to the same or like parts.  
         [0014]     As described above, a composite-metal-composite sandwich structure has been provided to combine advantages of composite materials and metal materials. The composite-metal-composite sandwich structure can have nuts formed therein and have good mechanical properties.  
         [0015]     The housings of mobile electronic devices nowadays are mainly made of metal materials. Because metal materials can be formed into complicated shapes and have nuts formed therein for easy assembly to components, they are main materials for electronic device housings. However, the primary shortcoming of a metallic housing is its relatively high density. In strengthening a metal sheet, its thickness is increased, which inevitably increases its weight.  
         [0016]     Composite materials are noted for their good mechanical properties while having relatively low density. Thus, a composite sheet with same weight as a metal sheet has higher strength. However, nuts cannot be deposed into a composite sheet as easily as nuts can be deposed into a metal sheet. Thus, a composite-metal-composite sandwich structure is provided to combine advantages of composite materials and metal materials.  
         [0017]      FIG. 1  illustrates a cross-sectional view of a composite-metal-composite sandwich structure according to one preferred embodiment of this invention. The sandwich structure  100  includes a metal sheet  102 , composite sheets  104   a / 104   b  and nuts  106 / 107 / 108 . Composite sheets  104   a  &amp;  104   b  are attached to two opposite sides of the metal sheet  102  to strengthen it and decrease its weight. In order to easily attach composite sheets  104   a  &amp;  104   b  to two opposite sides of the metal sheet  102 , two surfaces  110   a  and  110   b  are roughened by chemical processing or powder coating.  
         [0018]     Generally, the metal sheet  102  is preformed into a desired shape and nuts are deposed in predetermined positions. Composite sheets  104   a  &amp;  104   b  are formed with openings corresponding to the nuts such that nuts on the metal sheet  102  can be exposed. Nuts  106  &amp;  107  are positioned on only one side and exposed, wherein the nut  107  is mounted on the surface  110   a . The nut  108  is exposed on two opposite sides of the metal sheet  102 . Nuts  106 / 107 / 108  include threaded holes  106   a / 107   a / 108   a  for receiving bolts.  
         [0019]     According to preferred embodiments above, an A4-sized sandwich structure  100  (wherein the aluminum sheet  102  is 0.3 mm in thickness, composite sheets  104   a  and  104   b  are both 0.15 mm in thickness, and the total thickness is 0.6 mm) has a weight of 101.5 g, which is 33.5 g less than an aluminum sheet of the same area (A4) and the same thickness (0.6 mm).  
         [0020]     Preferred materials for the metal sheet  102  are selected from metal material with relatively low density, such as aluminum, magnesium, titanium or an alloy thereof, to meet the requirement of light weight. In order to avoid thermal weakening, the matrix material of the composite sheets  104   a  and  104   b  is selected from thermoset plastic materials. The fiber material of the composite sheets  104   a  and  104   b  is selected from carbon-fibers and glass-fibers.  
         [0021]     According to preferred embodiments of the present invention, the sandwich structure offers high mechanical strength, low thickness and light weight due to the composite materials and built-in nuts from the metal materials so as to overcome the prior art shortcomings. Moreover, less high-cost composite sheet is used in the sandwich structure to further reduce manufacturing costs as compared to a wholly composite structure.  
         [0022]     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.