Abstract:
A contact includes: an insulating housing, including a first face and a second face opposite to the first face, and formed with an insertion hole parallel to the first face and the second face, the first face formed with a first slit extending in an axial direction of the insertion hole, the insertion hole opening through the first slit; an electrically conductive case, formed with a second slit extending in the axial direction, and inserted into the insertion hole, the second slit facing the second face, a part of the case projected from the first face through the first slit; an electrically conductive plunger, disposed in the case, and having a distal end portion projected from the case; and a spring coil, disposed in the case, and urging the plunger in the axial direction.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to a contact in which a spring connector is disposed substantially in parallel with a circuit board. 
         [0002]    Referring to  FIGS. 11A to 12 , an example of a related-art contact in which a spring connector is disposed substantially in parallel with a circuit board will be briefly described.  FIGS. 11A ,  11 B and  11 C show an outer appearance of the related-art contact, in which  FIG. 11A  is a front view,  FIG. 11B  is a bottom view, and  FIG. 11C  is a side view.  FIG. 12  is an enlarged sectional view taken along a line A-A in  FIG. 11B , in which an internal structure of an electrically conductive metal tube is omitted. In  FIGS. 11A to 12 , each of spring connectors  10  includes a conductive metal tube  12  which is open at one end and closed at the other end, a spring coil (not shown) which is inserted into the conductive metal tube  12  from the open end side, and a plunger  14  formed of conductive metal which is additionally inserted into the conductive metal tube  12 . The open end of the conductive metal tube  12  is narrowed so that the plunger  14  can move in an axial direction having its distal end portion projected outward from the open end, but may not escape. Moreover, an insulating housing  16  formed of insulating resin or the like substantially in a shape of a box is provided with bottomed insertion holes  16   a  which are in parallel with a bottom face thereof and open at a side of the bottom face in a shape of slit in the axial direction. The spring connectors  10  are respectively inserted into these insertion holes  16   a,  and portions of outer peripheral faces of the respective conductive metal tubes  12  are slightly protruded from the openings on the bottom face of the insulating housing  16 , whereby the contact is constructed. The contact having the above described structure is mounted on the circuit board, and the portions of the outer peripheral faces of the conductive metal tubes  12  which are protruded from the bottom face of the insulating housing  16  are soldered to connecting terminals of the circuit board by solder reflowing or the like, whereby electrical connection is established. An art similar to the related art having such structure is disclosed in JP-A-2000-195600. 
         [0003]    In the structure of the related-art contact as described above, as shown in  FIG. 12 , a height H of the contact from a soldered face of the circuit board is a sum of an outer diameter D of the conductive metal tube  12  and a thickness T of the insulating housing  16  at a position where it covers this conductive metal tube  12 . Recently, a mobile phone or the like becomes more and more compact and thin, and therefore, it is keenly desired that the contact is also made thinner. However, in order to reduce the outer diameter D of the conductive metal tube  12 , it is required that the spring coil and the plunger  14  incorporated therein are made compact. This is technically difficult, and makes production difficult. Besides, by reducing the thickness T of the insulating housing  16  at the position covering the conductive metal tube  12 , mechanical strength of the insulating housing  16  would be weakened, and this has a limit in itself. It is to be noted that the contact having the above described structure is used, as an example, for electrical connection of battery packs in electronic appliances and so on. 
       SUMMARY 
       [0004]    It is therefore an object of the invention to provide a contact in which a spring connector is arranged substantially in parallel with a circuit board, and a height of the contact from a soldered face of the circuit board can be reduced. 
         [0005]    In order to achieve the object, according to the invention, there is provided a contact comprising: 
         [0006]    an insulating housing, including a first face and a second face opposite to the first face, and formed with an insertion hole parallel to the first face and the second face, the first face formed with a first slit extending in an axial direction of the insertion hole, the insertion hole opening through the first slit; 
         [0007]    an electrically conductive case, formed with a second slit extending in the axial direction, and inserted into the insertion hole, the second slit facing the second face, a part of the case projected from the first face through the first slit; 
         [0008]    an electrically conductive plunger, disposed in the case, and having a distal end portion projected from the case; and 
         [0009]    a spring coil, disposed in the case, and urging the plunger in the axial direction. 
         [0010]    The case may be formed with an engaging piece which can be elastically deformed, on a peripheral face. The insertion hole may be formed with an engaging recess which is to be engaged with the engaging piece. 
         [0011]    The plunger may have a large diameter portion a diameter of which is larger than a diameter of the distal end portion. The plunger may be movable in the case in the axial direction. The case may be provided with a sliding contact portion which has elasticity in a radial direction of the case so as to be in elastically contact with the large diameter portion, within a range in which the large diameter portion moves in the axial direction. 
         [0012]    The case may be formed with third slits which are substantially perpendicular to the axial direction, at both ends of the range in the axial direction. 
         [0013]    The case may be formed with a cutout which is substantially parallel to the axial direction, between the third slits. 
         [0014]    The sliding contact portion of the case may be formed with a convex rib which extends in the axial direction and which is in elastically contact with the large diameter portion. 
         [0015]    The sliding contact portion of the case may be formed in a wave shape in section. 
         [0016]    The insertion hole may be formed with a projecting portion projected toward the first face and being fitted to the second slit. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a perspective view showing an outer appearance of a contact in a first embodiment of the invention. 
           [0018]      FIG. 2  is a perspective view showing an outer appearance of an insulating housing as seen from a bottom face side. 
           [0019]      FIGS. 3A and 3B  show a case formed of a conductive metal sheet, in which  FIG. 3A  is a perspective view showing its outer appearance, and  FIG. 3B  is an enlarged sectional view taken along a line B-B in  FIG. 3A . 
           [0020]      FIG. 4  is a perspective view showing the outer appearance of the contact in the first embodiment of the invention, as seen from the bottom face side, for explaining its assembly. 
           [0021]      FIG. 5  is an enlarged sectional view taken along a line C-C in  FIG. 1 . 
           [0022]      FIG. 6  is a sectional view of  FIG. 1 , in which an internal structure of the case is omitted. 
           [0023]      FIG. 7  is a perspective view showing an outer appearance of a case which is used in a second embodiment of the invention. 
           [0024]      FIG. 8  is a perspective view showing an outer appearance of a case which is used in a third embodiment of the invention. 
           [0025]      FIGS. 9A and 9B  are views showing a case which is used in a fourth embodiment of the invention. 
           [0026]      FIGS. 10A and 10B  are views showing a case which is used in a fifth embodiment of the invention. 
           [0027]      FIGS. 11A ,  11 B and  11 C show an outer appearance of a related-art contact, in which  FIG. 11A  is a front view,  FIG. 11B  is a bottom view, and  FIG. 11C  is a side view. 
           [0028]      FIG. 12  is an enlarged sectional view taken along a line A-A in  FIG. 11B , in which an internal structure of a conductive metal tube is omitted. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0029]    Now, a first embodiment of the invention will be described referring to  FIGS. 1 to 6 . 
         [0030]    In  FIGS. 1 to 6 , an insulating housing  20  formed of insulating resin or the like substantially in a shape of box is provided with a plurality of bottomed insertion holes  20   a  which are parallel to a bottom face, and open in a slit-like shape in an axial direction at the bottom face side, in parallel with one another, in the same manner as in the related art. These insertion holes  20   a  are provided, in respective bottom portions thereof, with abutting recesses  20   b.  One ends of spring coils  22  are abutted against the abutting recesses  20   b  thereby to restrict movements of the spring coils  22  in a direction perpendicular to the axial direction. Moreover, engaging recesses  20   c  are formed on peripheral faces of the insertion holes  20   a  at the bottom side thereof. Further, rail portions  20   d  in a shape of rib which extend in the axial direction from the opening sides to the bottom side of the insertion holes  20   a  and project into inside of the insertion holes  20   a  are respectively provided on the peripheral faces of the insertion holes  20   a  opposed to the slit-like openings. In each of the rail portions  20   d,  a distal end face of the rib has a diameter in section which is equal to or slightly larger than an outer diameter of the spring coil  22 . In addition, solder reinforcing plates  24  for securing the insulating housing  20  by soldering to a surface of a circuit board  30  are provided at both ends of the insulating housing  20 . A case  26  formed of a conductive metal sheet has such an outer shape that it can be inserted into the insertion hole  20   a,  and is longer in the axial direction. The case  26  is formed in a C-shape or a U-shape in section, and provided with a slit-like opening  26   a  which is longer in the axial direction. A width of the opening  26   a  of the case  26  is set to be a width such that the rail portion  20   d  of the insertion hole  20   a  can be inserted to be fitted thereto. This case  26  has such a shape that it can be inserted into the insertion hole  20   a  with the opening  26   a  directed upward, in such a manner that a part of its outer peripheral face at an opposite side to the opening  26   a  may be slightly protruded from the slit-like opening on the bottom face of the insulating housing  20 . Moreover, the case  26  is provided with engaging pieces  26   b,  whereby the case  26  is elastically deformed easily, when it is inserted into the insertion hole  20   a,  thereby to reduce its outer diameter. When the case  26  has been inserted into the insertion hole  20   a,  the engaging pieces  26   b  are engaged with the engaging recesses  20   c  to be elastically restored, so that the case  26  may not escape in a direction opposite to an insertion direction. Further, on occasion of assembling, the spring coil  22  and a plunger  28  formed of conductive metal are inserted into the case  26 . A narrowed portion  26   c  is formed inside the case  26  for preventing the plunger  28  from escaping from the case  26 , and at the same time, for allowing a distal end portion  28   a  of the plunger  28  to be protruded outward. The plunger  28  having the distal end portion  28   a  which can pass the narrowed portion  26   c  and a large diameter portion  28   b  which cannot pass the narrowed portion  26   c  is movable in the axial direction. The case  26  is provided with a sliding contact portion  26   d  which has elasticity in a radial direction with respect to the axial direction so as to be elastically in contact with the large diameter portion  28   b  of the plunger  28  within a range in which the large diameter portion  28   b  moves in the axial direction. This sliding contact portion  26   d  is provided with slits  26   e  which are substantially perpendicular to the axial direction, at both ends of the range in which the large diameter portion  28   b  moves in the axial direction, except a part at an opposite side to the opening  26   a,  and so shaped as to have elasticity in the radial direction. An area enclosed by these slits  26   e  at the both ends is formed in a wave shape in section, as shown in  FIG. 3B , and convex ribs  26   f  which are longer in the axial direction are formed on an inner face of the case  26 . These convex ribs  26   f  are formed respectively between distal end portions and intermediate portions of the slits  26   e  in a circumferential direction, and also between base end portions and the intermediate portions, and adapted to be elastically in contact with the large diameter portion  28   b  of the plunger  28 . In assembling the contact according to the invention, the spring coil  22  is inserted into the insertion hole  20   a  in the insulating housing  20 , the plunger  28  is arranged, and then, the case  26  is inserted. After the case  26  has been inserted in the axial direction by a determined amount, the engaging pieces  26   b  are engaged with the engaging recesses  20   c  whereby an escape of the case  26  is prevented. In this state, the spring coil  22  is contracted so as to urge the plunger  28  with a determined elasticity. In a state where the spring coil  22 , the plunger  28  and the case  26  are incorporated into the insulating housing  20 , the spring connector which has the same function as the one employing the related-art conductive metal tube  12  is constructed by means of the spring coil  22 , the plunger  28 , the case  26 , and the rail portion  20   d.    
         [0031]    In the contact according to the invention having the above described structure, the one part of the outer peripheral face of the case  26  which is slightly protruded from the opening on the bottom face of the insulating housing  20  is brought into contact with the circuit board  30 , as shown in  FIG. 5 , and soldered to the circuit board  30  together with the solder reinforcing plate  24  by solder reflowing or the like. Because the case  26  having the C-shape or U-shape in section is used, as shown in  FIG. 6 , in place of the related-art conductive tube  12  which are shown in  FIGS. 11A to 12 , a height K of the case  26  from a soldered face of the circuit board  30  can be made smaller than in the related art in which the conductive metal tube  12  is used. Therefore, it is possible to make the height H of the contact according to the invention from the soldered face of the circuit board  30  smaller than in the related art, even though the thickness T of the insulating housing  20  in the portion covering the case  26  is the same. Moreover, because the case  26  is formed of sheet metal, its production cost can be reduced. Further, because the large diameter portion  28   b  of the plunger  28  is formed in an oval shape in section, as shown in  FIG. 5 , and a part of the insulating housing  20  is protruded into the case  26  though slightly, a space inside the case  26  is made non-circular in section, having a substantially D-shape or so. In this manner, the plunger  28  is restrained from rotating around its axis. Still further, because the convex ribs  26   f  provided in the sliding contact portion  26   d  is in elastically contact with the large diameter portion  28   b,  electrical conductivity of the sliding contact portion  26   b  can be reliably obtained. 
         [0032]    Then, referring to  FIG. 7 , a case which is used in a second embodiment of the invention will be described. In  FIG. 7 , members and structures which are equal or equivalent to the case used in the first embodiment as shown in  FIGS. 3A and 3B  are denoted with the same reference numerals, and overlapped descriptions will be omitted. 
         [0033]    A remarkable difference between a case  36  formed of a conductive metal sheet which is used in the second embodiment as shown in  FIG. 7  and the case  26  which is used in the first embodiment as shown in  FIGS. 3A and 3B  lies in positions of slits  36   e  defining a sliding contact portion  36   d.  In the case  36  as shown in  FIG. 7 , the slits  36   e  are provided at a forward side of the range in which the large diameter portion  28   b  of the plunger  28  moves, and the other slits  36   e  which are commonly used for forming the engaging pieces  26   b  are provided at a backward side, whereby the sliding contact portion  36   d  is defined. Although the convex ribs  26   f  which are provided in the first embodiment are not provided on this sliding contact portion  36   d,  it is also possible to provide them. 
         [0034]    Further, referring to  FIG. 8 , a case which is used in a third embodiment of the invention will be described. In  FIG. 8 , members and structures which are equal or equivalent to the case used in the first embodiment as shown in  FIGS. 3A and 3B  are denoted with the same reference numerals, and overlapped descriptions will be omitted. 
         [0035]    A case  46  formed of a conductive metal sheet which is used in the third embodiment as shown in  FIG. 8  is different from the case  26  which is used in the first embodiment as shown in  FIGS. 3A and 3B  in that the convex ribs  26   f  which are provided in the first embodiment are not provided on a sliding contact portion  46   d.    
         [0036]    Further, referring to  FIGS. 9A and 9B , a case which is used in a fourth embodiment of the invention will be described. In  FIGS. 9A and 9B , members and structures which are equal or equivalent to the case used in the first embodiment as shown in  FIGS. 3A and 3B  are denoted with the same reference numerals, and overlapped descriptions will be omitted. 
         [0037]    A case  56  formed of a conductive metal sheet which is used in the fourth embodiment as shown in  FIGS. 9A and 9B  is different from the case  26  which is used in the first embodiment as shown in  FIGS. 3A and 3B  in that cutouts  56   g  which are substantially parallel to the axial direction, and longer in the axial direction are formed at intermediate positions in the circumferential direction of the slits  26   e,  between the slits  26   e  defining the sliding contact portions  26   d  in the axial direction. By forming these cutouts  56   g,  a length of a portion connecting an idle end side and a base end side of the sliding contact portions  26   d  is made shorter. Accordingly, elastic deformation of the idle end side is easily achieved, and elasticity of the idle end side to be in elastically contact with the large diameter portion of the plunger  28  can be reduced. Therefore, sliding performance of the plunger  28  will not be deteriorated. 
         [0038]    Further, referring to  FIGS. 10A and 10B , a case which is used in a fifth embodiment of the invention will be described. In  FIGS. 10A and 10B , members and structures which are equal or equivalent to the case used in the first embodiment as shown in  FIGS. 3A and 3B  and in the fourth embodiment as shown in  FIGS. 9A and 9B  are denoted with the same reference numerals, and overlapped descriptions will be omitted. 
         [0039]    A case  66  formed of a conductive metal sheet which is used in the fifth embodiment as shown in  FIGS. 10A and 10B  is different from the case  26  which is used in the first embodiment as shown in  FIGS. 3A and 3B  in that cutouts  66   g  which are substantially parallel to the axial direction, and longer in the axial direction are formed at distal end side positions in the circumferential direction of the slits  26   e,  between the slits  26   e  defining the sliding contact portion  26   d  in the axial direction. By forming these cutouts  66   g  at the distal end side positions in the circumferential direction of the slits  26   e,  a length of portions connecting the sliding contact portions  26   d  to the case  26  at the base end side is made shorter. Accordingly, elastic deformation of the idle end side is easily achieved, and elasticity of the entire idle end side to be in elastically contact with the large diameter portion of the plunger  28  can be reduced. Therefore, sliding performance of the plunger  28  will not be deteriorated. 
         [0040]    In the above described embodiments, the one ends of the spring coils  22  are abutted against the abutting recesses  20   b  which are provided in the bottom of the bottomed insertion holes  20   a  of the insulating housing  20 . However, the invention is not limited to such structure, but each of the case  26  may be provided with a restraining portion against which the one end of the spring coil  22  is abutted. In such structure, the case  26  in which the plunger  28  and the spring coil  22  have been incorporated in advance may be inserted into the insertion hole  20   a  of the insulating housing  20 . Therefore, the insertion hole  20   a  need not be necessarily a bottomed hole, provided that an insertion length of the case  26  into the insertion hole  20   a  can be restricted. 
         [0041]    According to an aspect of the invention, the case formed of electrically conductive metal sheet and having a C-shape or a U-shape in section which is longer in the axial direction and has the opening in the axial direction is used in place of the related-art electrically conductive metal tube. Therefore, it is possible to reduce the height of the case, and accordingly, to reduce the height of the contact. Moreover, the case is formed of sheet metal, and can be easily manufactured at a lower cost than the tube. 
         [0042]    According to an aspect of the invention, the engaging piece provided in the case is engaged with the engaging recess provided in the insertion hole. Therefore, the case which has been inserted into the insertion hole is prevented from escaping, and can be easily assembled. 
         [0043]    According to an aspect of the invention, the case is provided with the sliding contact portion which is in elastically contact with the large diameter portion of the plunger. Therefore, electrical connection between the plunger and the case can be reliably established. 
         [0044]    According to an aspect of the invention, the slits which are substantially perpendicular to the axial direction are provided in the case at both ends of the range in which the large diameter portion of the plunger moves, and therefore, the sliding contact portion which is in elastically contact with the large diameter portion can be easily formed in the case. 
         [0045]    According to an aspect of the invention, the cutouts which are long and substantially parallel to the axial direction are provided between the slits defining the sliding contact portion. Therefore, a part of the sliding contact portion continued to the case becomes shorter in length accordingly, and becomes liable to be elastically deformed easily. In this manner, it is possible to reduce elasticity of the sliding contact portion when it is in elastically contact with the large diameter portion of the plunger. 
         [0046]    According to an aspect of the invention, the convex rib in the axial direction is formed in the sliding contact portion. Therefore, a distal end portion of this convex rib is abutted against the large diameter portion of the plunger, and reliable electrical connection can be obtained. 
         [0047]    According to an aspect of the invention, it is possible to easily form the convex rib in the axial direction in the sliding contact portion, by forming the sliding contact portion in a wave shape in section.