Patent Document

FIELD OF THE INVENTION 
     This invention relates to a keybutton-equipped device such as a cellular phone, a remote control etc., and more particularly to, a keybutton-equipped device that is easy to assemble and disassemble and that prevents foreign matter from getting into the case. 
     BACKGROUND OF THE INVENTION 
     Conventional keybutton-equipped devices typically have a keypad which is mounted inside the case and is provided with keybuttons exposed on the surface and penetrating through holes in the case equipped for the keybuttons. 
     Japanese utility model application laid-open No. 5-16571 (1993) discloses a keypad structure that switch-button member (keypad) is mounted inside the case and only the buttons are exposed on the surface and penetrating through holes in the case equipped for the buttons. In this structure, it is troublesome to assemble and disassemble the switch-button member. 
     Also, Japanese patent application laid-open No. 8-148054 (1996) discloses a key structure that switch-button member (keypad) is mounted inside the case, only the buttons are exposed on the surface and penetrating through holes in the case equipped for the buttons, and inside of the case is water-proofed by using covering sheet. In this structure, it is still troublesome to assemble and disassemble the switch-button member. Also, it allows dust or water to get into the case and to be left there. Further, the covering sheet may incur corrosion. 
     Thus, in the conventional keybutton-equipped devices, there is a problem that it is very troublesome to mount/remove the keypad. Also, they allow some liquid or dust to get into the case from a clearance between the hole in the case and the keybutton. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the invention to provide a keybutton-equipped device with a structure that allows the keypad to be mounted/removed easily and prevents foreign matter from getting into the case. 
     According to the invention, a keybutton-equipped device, comprises: 
     a board at a predetermined position on which a predetermined number of sensitive element (e.g., a sensor and switch) at a predetermined position is provided; 
     a case in which the board is mounted and a predetermined number of hole is formed at a position corresponding to the sensitive element on the board; and 
     a key pad which is of stretchy material (e.g., rubber and plastic) and is formed like a tubular body to cover and tighten the case, the keypad having a predetermined number of keybutton that is formed on the outer surface of the tubular body and at a position corresponding to the sensitive element on the board and gives an impulse (e.g., a physical impulse such as pressure, voltage, current, static electricity and magnetic force) to the sensitive element on the board through the hole in the case when it is pressed down. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The invention will be explained in more detail in conjunction with the appended drawings, wherein: 
     FIG. 1A is a perspective view showing a keypad in a first preferred embodiment according to the invention, 
     FIG. 1B is a cross sectional view cut along the line X-X′ in FIG. 1A, 
     FIG. 2 is a broken perspective view showing a case in the first embodiment of the invention, 
     FIG. 3 is a perspective view showing the process of assembling the keypad and the case in the first embodiment of the invention, 
     FIG. 4 is part of cross sectional view cut along the line Y-Y′ in FIG. 3 to show the contact/separation between electrodes  15  and  41 , 
     FIG. 5 is a cross sectional view (corresponding to FIG. 4 showing the cross sectional view cut along the line Y-Y′ in FIG. 3) showing a keybutton-equipped device with recessions in the keypad in a second preferred embodiment of the invention to show the contact/separation between the electrodes  15  and  41 , 
     FIG. 6 is a cross sectional view (corresponding to FIG. 4 showing the cross sectional view cut along the line Y-Y′ in FIG. 3) showing a keybutton-equipped device with dome switches over the electrodes of the board in a third preferred embodiment of the invention to show the contact/separation between electrodes  43  and  41 , and 
     FIG. 7 is a cross sectional view (corresponding to FIG. 4 showing the cross sectional view cut along the line Y-Y′ in FIG. 3) showing a keybutton-equipped device with a keybutton of different material in a fourth preferred embodiment of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A keybutton-equipped device in the first preferred embodiment according to the invention will be explained referring to the drawings. FIG. 1A is a perspective view showing a keypad in the first embodiment of the invention, and FIG. 1B is a cross sectional view cut along the line X-X′ in FIG.  1 A. FIG. 2 is a broken perspective view showing a case in the first embodiment of the invention. FIG. 3 is a perspective view showing the process of assembling the keypad and the case. 
     In FIGS. 1A and 1B, the keypad  10  is of stretchy material and formed like a tube. It has a predetermined number of keybuttons  12  on the outer surface of the tubular body which are disposed corresponding to electrodes  41  on a board  40  (see FIG.  2 ), a predetermined number of protrusions  13  on the inner surface of the tubular body which are disposed corresponding to the keybuttons  12 , and a predetermined number of electrodes  15  which are disposed on the top of the protrusions  13  and contact the electrodes  41  on the board  40  through holes  21  in the case  20  (FIG.  2 ). The keypad  10  is attached being tightly fit onto the case. The keypad  10  is composed of the tubular body, the keybuttons and the protrusions that are integrally formed using stretchy material. Although in FIG. 1A the keypad  10  is provided with an opening  11  that penetrates through the tubular body, it may be so formed that one opening  11  is shut up disposing recessions  22 ,  31  (see FIG. 2) of the case at the end of the case. Also, the protrusion  13  may be disposed on the inner surface of recessions that are provided on the inner surface of the tubular body. 
     As shown in FIG. 2, the case is composed of a case member  20  on the operation side, a case member  30  on the hand side and a board  40 . The case member  20  on the operation side is provided with the predetermined number of holes  21  at the positions corresponding to the electrodes  15  on the keypad  10 , and is provided with the recession  22  that positions the keypad  10  to middle and surrounding part in the longitudinal direction of the case. The case member  30  on the hand side is provided with the recession  31  that positions the keypad  10  to middle and surrounding part in the longitudinal direction of the case, at the position corresponding to the recession  22  of the case member  20  on the operation side. The board  40  is mounted inside both the case member  20  on the operation side and the case member  30  on the hand side. On the operation side of the board  40 , there are provided the predetermined number of electrodes  41  at the position corresponding to the holes  21  in the case member  20  on the operation side and the protrusions  13  or electrodes  15  on the keypad l 0 . The respective electrodes  41  on the board  40  neighbor so that the positive electrode and negative electrode do not contact. 
     The case (including the board  40 ) is pushed into the opening  11  of the keypad  10  while expanding it outward. In this process, the keypad  10  is fit onto the recessions  22 ,  31  in the case while aligning the protrusion  13  of the keypad  10  with the corresponding holes  21  in the case. 
     The operation of the keybutton-equipped device in the first embodiment is explained below. 
     FIG. 4 is part of cross sectional view cut along the line Y-Y′ in FIG. 3, and shows the contact/separation between the electrodes  15  and  41 . When the keybutton  12  is pressed, the electrode  15  on the protrusion  13  on the back surface contacts the electrode  41  on the board  40  to turn on electricity (between the positive electrode and negative electrode). On the other hand, when the keybutton  12  is released, it returns to the initial state before pressing it. 
     A keybutton-equipped device in the second preferred embodiment according to the invention will be explained below. 
     FIG. 5 is a cross sectional view (corresponding to FIG. 4 showing the cross sectional view cut along the line Y-Y′ in FIG. 3) showing a keybutton-equipped device with recessions in the keypad in the second embodiment of the invention, and shows the contact/separation between the electrodes  15  and  41 . In this embodiment, instead of the protrusion  13  of the keypad  10  in the first embodiment, there are provided a predetermined number of the recessions  14  with the electrode  15 . The other components are similar to those in the first embodiment. This embodiment is characterized by that the recession  14  turns into a protrusion when the keybutton  12  is pressed. In the assembling or disassembling, it is intended to prevent the protrusion (in the first embodiment) from scratching the case. In operation, when the keybutton  12  is pressed, the pressed part of the keybutton l 2  is recessed and the recession  14  turns into a protrusion. Thereby, the electrode  15  that was on the recession  14  is on the top of the protrusion created. Thus, the electrode  15  contacts the electrode  41  on the board  40  to turn on electricity (between the positive electrode and negative electrode). On the other hand, when the keybutton  12  is released, it returns to the initial state before pressing it. 
     A keybutton-equipped device in the third preferred embodiment according to the invention will be explained below. 
     FIG. 6 is a cross sectional view (corresponding to FIG. 4 showing the cross sectional view cut along the line Y-Y′ in FIG. 3) showing a keybutton-equipped device with dome switches over the electrodes of the board in the third embodiment of the invention, and shows the contact/separation between electrodes  43  and  41 . In this embodiment, instead of the electrode provided on the keypad in the first or second embodiment, there are provided the dome switches that an electrode is disposed on the concave side of a dome  42  which is of elastic material. The other components are similarly provided. This is advantageous in protecting the contacts of electrodes. In operation, when the keybutton  12  is pressed, the back side of the keybutton  12  (which is shown flat in an upper illustration in FIG. 6) presses down the electrode  43  while deforming the dome  42 . Thus, the electrode  43  contacts the electrode  41  on the board  40  to turn on electricity (between the positive electrode and negative electrode). On the other hand, when the keybutton  12  is released, the keybutton  12  and the dome  42  return to the initial state before pressing it. 
     A keybutton-equipped device in the fourth preferred embodiment according to the invention will be explained below. 
     FIG. 7 is a cross sectional view (corresponding to FIG. 4 showing the cross sectional view cut along the line Y-Y′ in FIG. 3) showing a keybutton-equipped device with a keybutton  12  of different material in the fourth embodiment of the invention. In this embodiment, the keybutton  12  or surrounding part of the keybutton  12  is of different material (e.g., hardmaterial and transparent material) from stretchy material used for the tubular body. The other components are similarly provided. This is helpful in improving the push-down feeling of keybutton or making the keybutton illuminated by providing a illuminant such as LED etc. adjacent to the electrode of the board even when it is dark. The operation is similar to that in the first embodiment (See FIG. 4) . Meanwhile the keybutton  12  is adhered to at the boundary of the tubular body (stretchy material) . The adhering face is not limited to flat, as shown in FIG. 7, at the side of the keybutton  12 , and may be uneven to get adhesive power. 
     Advantages of the Invention 
     In this invention, the case is tightened by the tubular keypad of stretchy material. Therefore, when removing the keypad, it is not necessary to disassemble the case, thus it is not troublesome. Also, the keypad is easy to assemble. 
     Also, the case is covered with and tightened by the tubular keypad of stretchy material. Therefore, the structure of the case can be strengthened by the stretching function of the keypad. 
     Further, since the keypad is attached covering the circumference of the case, there is no gap between the keybutton and the hole in the case that has existed in the conventional devices. Also, the enlarged contact area between the case and the keypad can prevent liquid or dust from getting into the case from outside. 
     Also, the keybutton and or surrounding part of the keybutton is of different material (e.g., hard material and transparent material) from stretchy material used for the tubular body. This is helpful in improving the push-down feeling of keybutton or making the keybutton illuminated by providing a illuminant such as LED etc. adjacent to the electrode of the board. 
     Further, in the keypad, the tubular body and the keybutton is formed integrally by conducting only a process of casting them in the lump. Therefore the manufacturing cost can be reduced. 
     Also, by providing a protrusion at position corresponding to a keybutton on the back side of the keypad, the push-down feeling of keybutton can be improved. 
     Also, instead of the protrusion on the back side of the keypad, the keybutton-equipped device may be provided with a recession with electrode that turns into a protrusion by pressing the keybutton. This helps assembling and disassembling the keypad since there is no protrusion to cause a friction against the case. 
     Also, instead of the electrode on the keypad, it may be provided with a dome switch that an electrode is disposed on the concave side of a dome which is of elastic material. This helps protecting the contacts of electrodes since the contacts are hidden by the dome. 
     Also, the recession provided on the surface of the case to receive the keypad helps making the appearance of device simple. 
     Although the invention has been described with respect to specific embodiment for complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modification and alternative constructions that may be occurred to one skilled in the art which fairly fall within the basic teaching here is set forth.

Technology Category: h