Abstract:
In a method of manufacturing a thin keypad of a keypad panel having a smooth surface, a mist surface or a lines layer, the method includes the steps of: preparing a mold with an internal bottom surface of a coarse surface, a smooth surface or a lines surface; applying an adhesive into the mold and coating a carrier onto the surface of the adhesive; rolling the surface of the carrier by a roller to level the adhesive in the mold; performing a ultraviolet projection to cure the adhesive to form a keypad layer on the carrier; filming a ground color layer, a function color layer and a font color layer sequentially on the carrier as the background of the keypad panel; and hot pressing and combining the keypad layer and silicon to produce the keypad panel.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a keypad assembly, and more particular to a manufacturing method of a thin keypad assembly. 
   2. Description of Prior Art 
   In addition to the function of a mobile phone, consumers also take other factors including the innovative appearance and the compact size of the mobile phone into consideration for the purchase the mobile phone. Therefore, some mobile phones print color patterns on the housing or keypad or produce three-dimensional lines directly on the housing of the mobile phone to improve the added-value of the product and promote the purchasing desire of the consumers. 
   Referring to  FIG. 1A  and a traditional way of producing three-dimensional lines as disclosed in R.O.C. Pat. No. M304441, the patented technology discloses a manufacturing method of a thin keypad assembly that attaches a first transparent layer  2   a  onto a substrate  1   a , a first color layer  3   a  and a color opening area  31   a  onto the first transparent layer  2   a , a second transparent layer  4   a  onto the first color layer  3   a , and a second color layer  5  onto the second transparent layer  4   a  for providing an external look with different colors and lines for the depth of field by the aforementioned display structure and mode for the requirement of different visual appearances or functions. However, such manufacturing method takes too much time and efforts, and thus incurring a high manufacturing cost of the product easily. 
   Referring to  FIG. 1B  and R.O.C. Pat. No. M301397 for another keypad assembly with lines manufactured therein, a lines layer  1   b  is included between a thin film layer  2   b  and an elastic layer  3   b  for producing a flare effect. Since a lines layer  1   b  is created between the thin film layer  2   b  and the elastic layer  3   b , therefore such patented technology not only adds more steps to the production or manufacturing procedure, but also consumes much manufacturing time and increases the thickness of the keypad. Obviously, an increased thickness is a disadvantage to the design of a thin film keypad. 
   SUMMARY OF THE INVENTION 
   In view of the foregoing shortcomings of the prior art, the inventor of the present invention based on years of experience in the related industry to conduct experiments and modifications, and finally developed a manufacturing method of a thin keypad assembly in accordance with the present invention. 
   It is a primary objective of the present invention to provide a method of manufacturing a keypad in a mold while forming a smooth surface, a mist surface or a lines layer directly on the surface of the keypad panel or keycaps. The invention not only simplifies the manufacturing procedure and time, but also avoids an increased thickness of the keypad assembly. 
   To achieve the foregoing objective, a manufacturing method of a thin keypad of a keypad panel having a smooth surface, a mist surface or a lines layer in accordance with the present invention includes the steps of: preparing a mold with an internal bottom surface of a coarse surface, a smooth surface or a lines surface; applying an adhesive into the mold and coating a carrier onto the surface of the adhesive; rolling the surface of the carrier to level the adhesive in the mold by a roller; performing a ultraviolet projection to cure the adhesive to form a keypad layer on the carrier; filming a ground color layer while forming a pattern of hollow characters, numbers or different symbols on the ground color layer, filming a function color layer on the surface of the ground color layer, and a font color layer on the function color layer, and putting the formed keypad layer and silicon into another mold for a hot pressing process for combining the keypad layer and silicon and forming an elastic layer by silicon to complete the manufacture of the keypad panel. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
     The features of the invention believed to be novel are set forth with particularity in the appended claims. The invention itself however may be best understood by reference to the following detailed description of the invention, which describes certain exemplary embodiments of the invention, taken in conjunction with the accompanying drawings in which: 
       FIG. 1A  is a schematic view of an appearance of an assembly of a conventional product; 
       FIG. 1B  is a schematic view of a conventional keypad assembly; 
       FIG. 2A  is a flow chart of manufacturing a first type of thin film keypad in accordance with the present invention; 
       FIG. 2B  is a flow chart of manufacturing a second type of thin film keypad in accordance with the present invention; 
       FIG. 3  is a schematic view of a carrier of the present invention; 
       FIG. 4  is a schematic view of manufacturing a first type of first mold in accordance with the present invention; 
       FIG. 5  is a schematic view of rolling a first mold as depicted in  FIG. 4 ; 
       FIG. 6  is a schematic view of a backside printing of a keypad panel of the present invention; 
       FIG. 7  is a side view of  FIG. 6 ; 
       FIG. 8  is a schematic view of putting a keypad panel and silicon into a second mold in accordance with the present invention; 
       FIG. 9  is a side view of combining a keypad panel and an elastic layer in accordance with the present invention; 
       FIG. 10  is an exploded view of combining and using a keypad panel, a light emitting layer and a flexible printed circuit board in accordance with the present invention; 
       FIG. 11  is a side view of  FIG. 10 ; 
       FIG. 12  is a schematic view of a pressing movement of  FIG. 11 ; 
       FIG. 13  is a side view of lines on a surface of a keypad panel of the present invention; 
       FIG. 14  is a front view of lines on a surface of a keypad panel of the present invention; 
       FIG. 15  is an enlarged view of a portion of a second type of first mold in accordance with the present invention; 
       FIG. 16  is an enlarged view of a portion of a third type of first mold in accordance with the present invention; 
       FIG. 17  is a side view of an assembled keypad panel of  FIG. 16 ; 
       FIG. 18  is an enlarged view of a portion of a fourth type of first mold in accordance with the present invention; 
       FIG. 19  is a side view of an assembled keypad panel of  FIG. 18 ; 
       FIG. 20  is an enlarged view of a portion of a fifth type of first mold in accordance with the present invention; 
       FIG. 21  is a side view of an assembled keypad panel of  FIG. 20 ; 
       FIG. 22  is a schematic view of a keypad assembly applied in a mobile phone in accordance with the present invention; and 
       FIG. 23  is a schematic view of a keypad assembly applied in an automobile stereo panel in accordance with the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The technical characteristics, features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments with reference to the accompanying drawings. The drawings are provided for reference and illustration only, but not intended for limiting the present invention. 
   Referring to  FIG. 2A  for a flow chart of manufacturing a thin film keypad of the present invention, the manufacturing method provided for manufacturing a keypad assembly with patterned keycaps comprises the following steps: 
   Step  100 : Prepare a carrier  2  made of a Polycarbonate film. 
   Step  102 : Stamp a locating hole  21  at the surface of the carrier  2  (see  FIG. 3  as well), wherein the locating hole  21  is provided for the carrier  2  to be positioned with a guiding pillar  13  of a first mold  1 . 
   Step  104 : Prepare the first mold  1  (see  FIG. 4 ), wherein the first mold  1  contains a first mold cavity  11 , and the first mold cavity  11  contains a plurality of second mold cavities  12 , and the second mold cavities  12  are provided for forming the shape of the keycap, and the bottom surface  111  of the first mold cavity  11  is a coarse surface, and the bottom surface  121  of the second mold cavity  12  is a smooth surface. 
   Step  106 : Apply an adhesive  3 ′ into the first mold cavity  11  of the first mold  1  (See  FIG. 4 ), wherein the adhesive  3 ′ is a ultraviolet curable resin. 
   Step  108 : Coat the carrier  2  onto the surface of the adhesive  3 ′ (See  FIG. 4 ). 
   Step  110 : Roll the surface of the carrier  2  by a roller  4  to fill up the adhesive  3 ′ into the first and second mold cavities  11 ,  12 , while squeezing the air among the adhesive  3 ′, the first and second mold cavities  11 ,  12  and the carrier  2  to the outside to prevent any air bubble formed by the air remained in the adhesive  3 ′ or between the adhesive  3 ′ and the carrier  2 . 
   Step  112 : Perform a ultraviolet projection to the rolled first mold  1  to cure the ultraviolet curable resin and form a keypad layer  3  by the adhesive  3 ′. 
   Step  114 : Remove the keypad layer  3  and the carrier  2  from the first mold  1  and then cut away excessive materials at the edge and print a locating hole. 
   Step  116 : Print a black ink onto another surface of the carrier  2  to form a ground color layer  5  (see  FIG. 6 ), while forming a pattern  51  of hollow characters, numbers or different symbols onto the ground color layer  5  corresponding to keycaps. 
   Step  118 : Print a layer of red ink onto the surface of a pattern  511  of a hollow end key of the ground color layer  5  to form a function color layer  511 ′ (See  FIG. 6 ). 
   Step  120 : Print a layer of green ink onto the surface of a pattern  512  of a hollow dialing key of the ground color layer  5  to form a function color layer  512 ′ (See  FIG. 6 ). 
   Step  122 : Print a layer of white ink onto the surface of a pattern  513  of a hollow character and number key  513  of the ground color layer  5  to form a function color layer  513 ′ (See  FIG. 6 ), such that the font key  513  of the hollow characters and numbers is displayed in white color. 
   Step  124 : Print a layer of glue  52  onto the surfaces of the ground color layer  5 , the function color layer  511 ′,  512 ′ and the font color layer  513 ′ (See  FIGS. 6 and 7 ). 
   Step  126 : Put the keypad layer  3 , carrier  2  and silicon  6 ′ simultaneously into the second mold  1 ′ after the keypad panel is manufactured (See  FIGS. 8 and 9 ), and combine the carrier  2  with silicon  6 ′ by using a hot pressing technology, while forming an elastic layer  6  from the silicon  6 , a support portion  61   a  on the elastic layer  6  and a protrusion  62  corresponding to the keycap. 
   Step  128 : Remove the hot pressed keypad panel  10  and silicon  6 ′ from the second mold  1 ′, and stamp the external form of the keypad panel  10  to complete the manufacture of the keypad panel. 
   Referring to  FIG. 2B  for a flow chart of manufacturing a second type of thin film keypad, this manufacturing procedure is substantially the same as that illustrated in  FIG. 2A , and the only difference resides on that Step  115  is added between Steps  114  and  116 . In Step  115 , an aluminum material with a light transmittance of approximately 40% is spluttered at the backside of the carrier  2  first before printing the ground color layer  5 , so that the finished goods of the keypad panel can achieve the effect of a metal-like panel. 
   Referring to  FIG. 10  for an exploded view of combining and using a keypad panel, a light emitting layer and a flexible printed circuit board in accordance with the present invention, the keypad assembly comprises a flexible printed circuit board  7 , a light emitting layer  8 , an elastic layer  6  and a keypad layer  3 . 
   The aforementioned flexible printed circuit board  7  is a thin film flexible printed circuit board printed with a circuit  71  and a contact point  72 . 
   The light emitting layer  8  includes a luminescent laminate  81  disposed on the surface of the flexible printed circuit board  7 , and the luminescent laminate  81  as shown in  FIG. 10  is an electro luminescent panel, and a plurality of metal domes  82  are disposed on another surface of the luminescent laminate  81 , and the metal dome  82  is corresponding to the contact point  72  the flexible printed circuit board  7 . 
   The elastic layer  6  is disposed on the light emitting layer  8  (See  FIG. 11 ) and includes a support portion  61 , and a protrusion  62  disposed between the support portions  61  and corresponding to the metal dome  82 . 
   The keypad layer  3  includes a carrier  2  attached onto the surface of the elastic layer  6 , and the carrier  2  includes a keypad group  31  comprised of a plurality of keycaps  311 . Since the bottom surface  111  of the first mold cavity  11  is a coarse surface, and the bottom surface  121  of the second mold cavity  12  is a smooth surface, therefore the surface of the manufactured keycap  311  is a smooth surface, and the keycap  311  and the panel holder  312  connected to the keycap  311  have mist surfaces. 
   Referring to  FIGS. 11 and 12  for a side view of  FIG. 10  and a schematic view of a pressing movement in accordance with the present invention respectively, a surface light source is produced by the luminescent laminate  81  of the light emitting layer  8  and projected directly onto the bottom of the elastic layer  6  when the keypad assembly is used. The light passes through the elastic layer  6  and the carrier  2 , such that the surface of the keycap  311  of the keypad panel  3  shows a light transmitting effect. 
   When a user applies an external force to the surface of the keycap  311  to deform the carrier  2  and the elastic layer  6 , the protrusion  62  is pressed against the surface of the luminescent laminate  81 , and then the metal dome  82  is deformed to press the flexible printed circuit board  7  and touch the contact point  72 , so as to produce an output of an operating signal. 
   Referring to  FIGS. 13 and 14  for a side view and a front view of lines at the surface of the keypad panel of the present invention as well as  FIG. 15  for an enlarged view of a portion of a second type of first mold in accordance with the present invention, lines  112 ,  122  are created on the bottom surfaces  111 ,  121  of the first mold cavity  11  and the second mold cavity  12  of the first mold  1  to form a lines layer  3 ″ on the surfaces of the produced keycap  311  and panel holder  312  of the keypad panel  3 . The lines as shown in these figures are spinnings, straight stripes or Archimedean screws. 
   Referring to  FIGS. 16 and 17  for an enlarged view of a portion of a third type of first mold in accordance with the present and a side view of a manufactured keypad panel of  FIG. 16  respectively, if the first mold  1  does not contain a second mold cavity  12  in the first mold cavity  11 , there will be no keycap  311  protruded from the surface of the keypad panel  3  when the keypad panel  3  is manufactured, such that the surface of the keypad panel  3  is a flat level surface. Referring to  FIGS. 18 and 19  for an enlarged view of a portion of a first mold in accordance with the present invention and a side view of a manufactured keypad panel of  FIG. 18  respectively, the whole surface of the manufactured keypad panel  3  forms a lines layer  3 ″, if the bottom surface  111  of the first mold cavity  11  in the first mold  1  has lines  112 . The lines illustrated in the figures are spinnings, straight stripes or Archimedean screws. 
   Referring to  FIGS. 20 and 21  for an enlarged view of a portion of a fifth type of first mold in accordance with the present invention and a side view of a manufactured keypad panel of  FIG. 20  respectively, a lines layer  3 ″ is formed on the flat surface of a keycap  311  of the manufactured keypad panel  3 , if the bottom surface  111  of the first mold cavity  11  in the first mold  1  has lines  112  corresponding to the position of the keycap  311 . The lines layer shown in the figure is a spinning, a straight stripe or an Archimedean screw. 
   Referring to  FIG. 22  for a schematic view of a keypad assembly applied in a mobile phone in accordance with the present invention, the keypad assembly is installed to the mobile phone  9  for its use, the surface light source in the keypad assembly is projected directly onto the keypad panel  3 , such that the surface of the keycap  311  of the keypad panel  3  shows a light transmitting effect. 
   Referring to  FIG. 23  for a schematic view of a keypad assembly applied in an automobile stereo panel in accordance with the present invention, the panel of the keypad assembly of the invention can be applied to a mobile phone, and also installed to the automobile stereo panel  20  for controlling an air-conditioning system, an audio/video system and a satellite navigation system, etc. 
   The present invention is illustrated with reference to the preferred embodiment and not intended to limit the patent scope of the present invention. Various substitutions and modifications have suggested in the foregoing description, and other will occur to those of ordinary skill in the art. Therefore, all such substitutions and modifications are intended to be embraced within the scope of the invention as defined in the appended claims.