Abstract:
An exemplary key includes a main body and a filling portion. The main body is made of ceramic material. The main body defines a through hole therein. The filling portion fills the through hole. The filling portion is capable of allowing light passing through the filling portion.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to input keys, and particularly, to an input key used in a portable electronic device. 
         [0003]    2. Description of the Related Art 
         [0004]    Generally, a majority of portable electronic devices, such as personal digital assistants (PDAs), mobile phones, MP3 players and MP4 players, have keypads configured for users to input information. A keypad includes a pad and a plurality of input keys positioned on the pad. 
         [0005]    Typically, an input key (hereinafter key) is made of transparent plastic, because of the following reasons: firstly, plastic has low melting point and high fluidity, thus keys having all kind of configurations can be easily formed by plastic; secondly, a color layer can be easily coated on keys made of plastic to form predetermined patterns; thirdly, light emitting from a light source positioned on a bottom of the key is capable of passing through the key to facilitate its use at night or during other conditions when ambient light is poor. 
         [0006]    However, problems such as distortion, scratching, and abrasion often occur due to poor surface hardness of the key. If the key is distorted, scratched or abraded, the appearance of the key may not be as pleasant as the original appearance. 
         [0007]    What is needed, therefore, is a new type of key that can overcome the above-mentioned shortcomings such as distortion, scratching, and abrasion of the key. 
       SUMMARY 
       [0008]    A key includes a main body and a filling portion. The main body is made of ceramic material. The main body defines a through hole therein. The filling portion fills the through hole. The filling portion is capable of allowing light passing through the filling portion. 
         [0009]    Other advantages and novel features will become more apparent from the following detailed description of various embodiments, when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present key. Moreover, in the drawings, like reference numerals designate corresponding parts throughout several views, and all the views are schematic. 
           [0011]      FIG. 1  is an isometric view of the key according to a first embodiment of the present invention. 
           [0012]      FIG. 2  is a side, cross-sectional view of the key in  FIG. 1 , taken along the line II-II. 
           [0013]      FIG. 3  is a side, cross-sectional view of the key according to a second embodiment of the present invention. 
           [0014]      FIG. 4  is a side, cross-sectional view of the key according to a third embodiment of the present invention. 
           [0015]      FIG. 5  is a side, cross-sectional view of the key according to a fourth embodiment of the present invention. 
           [0016]      FIG. 6  is a side, cross-sectional view of the key according to a fifth embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0017]    Reference will now be made to the drawings to describe the embodiments of the key in detail. 
         [0018]    Referring to  FIGS. 1 and 2 , an input key  10  in accordance with a first embodiment of the present invention is shown. The key  10  includes a main body  11  and a filling portion  13 . The main body  11  is integrally formed with the filling portion  13 . The main body  11  is made of ceramic material, such as zirconia (ZrO 2 ) or alumina (Al 2 O 3 ). The filling portion  13  is made transparent materials such as glass and plastic. In the illustrated embodiment, the filling portion  13  is made of transparent plastic. Preferably, a melting point temperature of the plastic is lower than that of the glass, therefore, the plastic filling portion  13  can be easily molded. 
         [0019]    In the illustrated embodiment, the main body  11  includes a top surface  111 , a bottom surface  113 , and a side surface  115 . The top surface  111  is configured for being pressed. The top surface  111  and the bottom surface  113  are on opposite sides of the main body  11 . The side surface  115  connects the top surface  111  to the bottom surface  112 . Both the top surface  111  and the bottom surface  113  are circular planes. The side surface  115  is a cylindrical surface. The main body  11  defines a through hole  117  communicating between the top surface  111  and the bottom surface  113 . An inner wall forming the through hole  117  defines an annular depression  119 . The filling portion  13  is formed in the through hole  117  by injection molding, and as a result, the filling portion  13  would further form a flange  133  corresponding to the depression  119 . The flange  133  locates in the depression  119 , thereby enhancing bonding strength between the filling portion  13  and the main body  11 . 
         [0020]    In addition, the main body  11  also defines an assembly hole  114  such that the key  10  can be easily mounted on a keypad (not labeled). It can be understood that, the assembly hole  114  can be omitted. 
         [0021]    A method of making the key  10  includes the following steps: firstly, a preforming having the through hole  117  is formed by dry pressing ceramic materials. Then, the preform undergoes an abrading process and then a polishing process to form the main body  11 . Afterwards, the main body  11  is integrally formed with the filling portion  13  by injection molding. Thus, the key  10  is achieved. 
         [0022]    Since the filling portion  13  is made of transparent material and the through hole  117  is filled with the filling portion  13 , light is capable of passing through the filling portion  13  in the through hole  117  to illuminate the key  20 . 
         [0023]    The key  10  has a deformation resistance ability such as high anti-distortion property, high anti-scratch property, and anti-abrasion property because ceramic materials have high hardness. Also, the filling portion  13  is received in the through hole  117  of the main body  11 , an exposed, outer surface of the filling portion  13  is relatively small, generally not exceeding 0.2% to 50% of the top surface  111 . In other words, the filling portion  13  is embedded in the main body  11 , therefore, the filling portion  13  is seldom deformed, scratched, and abraded due to a protection of the main body  11 . Therefore, the key  10  has high anti-distortion ability, high anti-scratch ability, and anti-abrasion ability. 
         [0024]    In addition, because a potion of the filling portion  13  is exposed out of the main body  11 , the filling portion  13  can be configured to be the following predetermined patterns: letters, numbers, symbols, and so on. Therefore, the patterns formed by the filling portion  13  does not decolorize easily, thus the key  10  has a high color preservation. It can be understood that, an ink layer can also be printed on the portion of the filling portion  13  exposed out of the main body  11 , thereby forming predetermined patterns. 
         [0025]    Furthermore, a desired color of the main body  11  can be achieved by varying ingredients of the ceramic material. In other words, some ingredients of the ceramic material of the main body  11  may have the desired color property, thus the key  10  has a high color preservation. 
         [0026]    Referring to  FIG. 3 , a key  20  in accordance with a second embodiment of the present invention is shown. The key  20  include a main body  21  and a filling portion  23 . The main body  21  includes a top surface  211 , a bottom surface  213 , a side surface  215 , and a through hole  217 . The filling portion  23  is formed in the through hole  217  by injection molding, an inner wall forming the through hole  217  forms a step portion  2171 . Correspondingly, the filling portion  23  also forms a corresponding step portion (not labeled). The step portion  2171  engages with the step portion of the filling portion  23 , thereby enhancing a bonding strength between the main body  21  and the filling portion  23 . In addition, when the key  20  is pressed, an external force is applied to the filling portion  23 , the step portion  2171  forms a force to the filling portion  23  and acts as a restricting member that prevents the filling portion  23  from detaching out of the main body  21 . 
         [0027]    Referring to  FIG. 4 , a key  30  in accordance with a third embodiment of the present invention is shown. The key  30  includes a main body  31  and a filling portion  33 . The main body  31  includes a top surface  311 , a bottom surface  313 , a side surface  315 , and a through hole  317 . The filling portion  33  is formed in the through hole  317  by injection molding, an inner wall forming the through hole  317  forms a flange  3171 . The filling portion  33  defines a depression (not labeled). The flange  3171  is received in the depression, thereby enhancing bonding strength between the main body  31  and the filling portion  33 . In addition, a height of the flange  3171  are configured to be small, thus, light passing through the through hole  317  will not be reflected by the flange  3171 , and, thus, a shadow of the flange  3171  cannot be seen when viewing the key  30  externally. 
         [0028]    In the keys described above, a boundary of the through hole  117 ,  217 ,  317  and the filling portion  13 ,  23 ,  33  cooperatively form a latch structure such as a combination of the depression and the flange, the step portions, to increase bonding strength between the main bodies  11 ,  21 ,  31  and the filling portions  13 ,  23 ,  33 . It can be understood that, a shape of the through hole can also be other shapes, such as shapes of the key  40  and the key  50  shown in  FIGS. 5 and 6  respectively, the through hole can also have a pyramidal configuration. In addition, the through hole can also communicate between the side surface and the top surface. Furthermore, an inner wall forming the through hole can also be rough surface with center line average roughness (Ra) less than 200μ, thereby enhancing bonding strength between the main body and the filling portion. 
         [0029]    It can be understood that, the main body can also be formed with other methods such as injection molding. The filling portion can also be formed with other methods such as plastic impregnation. 
         [0030]    It can be understood that, in the above mentioned keys  10 ,  20  and  30 , the top surface  113 ,  211 ,  311  are planar to achieve a good sense of touch. The top surface of main body can also be other shapes, such as a concave surface or a convex surface. In addition, to improve an appearance of the keys, a top view of the main body can be any other shapes, such as circular, ellipse, and polygon. 
         [0031]    It can be understood that, the key can be used for other portable electronic devices such as keypads of computers. 
         [0032]    Finally, while the preferred embodiment has been described and illustrated, the invention is not to be construed as being limited thereto. Various modifications can be made to the embodiments by those skilled in the art without departing from the true spirit and scope of the invention as defined by the appended claims.