Patent Publication Number: US-2011076455-A1

Title: Key and method of manufacturing the same

Description:
BACKGROUND 
     1. Technical Field 
     The present invention relates to a key and a method of manufacturing the key. 
     2. Description of the Related Art 
     Generally, a majority of electronic devices, such as personal digital assistants (PDAs), mobile phones, MP3 players and MP4 players, provide keypads by means of which information is input. A keypad includes a pad and a plurality of input keys positioned thereon. 
     Typically, an input key (hereinafter key) is manufactured as follows. Molten plastic material is injection molded to form a plastic main body having a contact surface, and an ink layer is formed on the contact surface of the main body according to predetermined patterns to represent characters. However, with use, the ink layer may fade and even disappear. 
     Therefore, there is room for improvement within the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disclosure. 
         FIG. 1  is a cross section of one embodiment of a key including a preform, a first molded layer formed on a first side surface of the preform, a second molded layer formed on the second side surface of the perform, and a film. 
         FIG. 2  is a cross section of the film of  FIG. 1 . 
         FIG. 3  is a cross section of an ink layer formed on the film of  FIG. 2 . 
         FIG. 4  is a cross section of the preform, the film, and the ink layer of  FIG. 3  after hot pressing. 
         FIG. 5  is a cross section of the first molded layer of  FIG. 1  formed on the first side surface of the preform of  FIG. 4 . 
         FIG. 6  is a cross section of an embodiment of an injection mold used to manufacture the key of  FIG. 1 . 
         FIG. 7  is a cross section of a key having a stub bar manufactured by the injection mold of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a key  10  includes a preform  15 , a first molded layer  17 , and a second molded layer  19 . The preform  15  has a first side surface  153  and a second side surface  155  opposite to the first side surface  153 . The first molded layer  17  is formed on the first side surface  153  by injection molding. The second molded layer  19  is formed on the second side surface  155  by injection molding. The preform  15 , the first molded layer  17 , and the second molded layer  19  cooperatively define a depression  21  for receiving components (not shown) positioned on an electronic device. A part of the first molded layer  17  forms the interior of the depression  21 . 
     A periphery of the first molded layer  17  forms an assembly portion  173  that engages with components of the electronic device to efficiently fix the key  10  to the electronic device. 
     In the illustrated embodiment, the preform  15  further includes a film  11  and an ink layer  13  formed on a side surface of the film  11 . The preform  15  is made by hot pressing and cutting the film  11 . The film  11  may be plastic such as polycarbonate, acrylonitrile-butadiene-styrene terpolymer, polystyrene, poly vinyl chloride, or polycarbonate/acrylonitrile-butadiene-styrene. A thickness of ink layer  13  is about 0.1 millimeters (mm) to about 0.2 mm. 
     The first molded layer  17  may be plastic such as polycarbonate, acrylonitrile-butadiene-styrene terpolymer, polystyrene, poly vinyl chloride, or polycarbonate/acrylonitrile-butadiene-styrene. 
     A thickness of the first molded layer  17  may be about 0.6 mm to about 1.0 mm. 
     The second molded layer  19  is transparent or semi-transparent and may be plastic such as polycarbonate, acrylonitrile-butadiene-styrene terpolymer or poly-methylmethacrylate. Additionally, a portion of the second layer  19  on the periphery of the first molder layer  17  is substantially parallel to a portion of the ink layer  13  on the periphery of the first molder layer  17 . 
     One embodiment of a method of manufacturing the key  10  is as follows. 
     Referring to  FIG. 2 , a film  11  is first provided. 
     Referring to  FIG. 3 , an ink layer  13  is then formed on a surface of the film  11  by printing. 
     Referring to  FIG. 4 , the film  11  is hot pressed to define a plurality of depressions  111  with a part of the ink layer  13  as the interior of the depressions  111 . The film  11  is cut and a plurality of preforms  15  are formed. Each preform  15  corresponds to a depression  111  and has a first side surface  153  and a second side surface  155  opposite thereto. 
     Referring to  FIG. 5 , a first molded layer  17  is formed on the first side surface  153  of the preform  15  by injection molding. The first molded layer  17 , the film  11 , and the ink layer  13  cooperatively define a depression  171 . 
     Referring to  FIG. 6 , an injection mold  50  is provided. The injection mold  50  includes a cavity  51 , a runner  53 , and a gate  55  communicating the runner  53  with the cavity  51 . 
     The preform  15  and the first molded layer  17  are received in the cavity  51  such that the gate  55  substantially aligns with an edge of the preform  15  and is adjacent to the second side surface  155 , and the gate  55  substantially parallels the ink layer  13 . 
     Also referring to  FIG. 7 , a molten material of a second molded layer  19  passes the runner  53  and the gate  55 , and enters the cavity  51 . The molten material of the second molded layer  19  is transparent or semi-transparent and may be plastic such as polycarbonate, acrylonitrile-butadiene-styrene terpolymer or poly-methylmethacrylate. The molten material of the second molded layer  19  is solidified and the second molded layer  19  is formed on the second side surface  155  of the preform  15 . 
     A stub bar  23  is cut off, thus yielding the key  10  as shown in  FIG. 1 . 
     Since the gate  55  substantially aligns with an edge of the preform  15  and is adjacent to the second side surface  155 , and the gate  55  is substantially parallel to the ink layer  13 , the second molded layer  19  may be formed on the second side surface  155  of the preform  15  directly without additional steps and the ink layer  13  remains protected. 
     Finally, while various embodiments have been described and illustrated, the embodiments are 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 embodiments as defined by the appended claims.