Patent Publication Number: US-6706979-B1

Title: Vibration switch

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a vibration switch, more particularly to a vibration switch with two electrically conductive rollable bodies which abut against two tangential areas of two electric contact bodies to establish electric contact between the electric contact bodies, and which will lurch towards a farthermost area of a respective one of the electric contact bodies when the vibration switch is in an unsteady state so as to break the electric contact. 
     2. Description of the Related Art 
     Referring to FIGS. 1 and 2, a conventional vibration switch  1  is shown to include a metal housing  11  with an accommodation chamber  111  for receiving a deflectable electric contact body  12 , such as a coil spring. An anchoring end  121  of the electric contact body  12  is sleeved on a plug portion  112  of the housing  11  such that a contact terminal end  122  thereof is held along an axis. A first electric contact terminal  113  extends from a side wall of the housing  11  downwardly. A second electric terminal  14  has a contact end inserted into the contact terminal end  122  through a through hole  131  in an insulating plug member  13 . 
     As shown in FIG. 3, when the housing  11  is jerked by a force (F), the contact terminal end  122  of the electric contact body  12  is deflected radially as a result of an inertial force so as to contact the second electric terminal  14 , thereby establishing an electrical connection between the first and second electric contact terminals  113 , 14 . However, when the housing  11  is jerked by a force (not shown) from a direction substantially parallel to the axis, the extent of deflection of the contact terminal end  122  is relatively small so that the contact terminal end  122  may not be able to contact the second electric terminal  14  to establish the electrical connection between the terminals  113 , 14 . 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a vibration switch which can be instantly disposed in a switch-off state when jerked by a force coming from any direction. 
     According to this invention, the vibration switch is adapted to be disposed in electric contact with a support, and includes a housing adapted to be mounted on the support in an upright direction. The housing includes an upper wall and a lower wall spaced apart from each other in the upright direction to confine an accommodation chamber. 
     First and second electric contact bodies are disposed in the accommodation chamber, and respectively have first and second rolling surfaces that are spaced apart from each other along a centerline which is oriented in one of the upright direction and a longitudinal direction that is transverse to the upright direction. The first and second rolling surfaces respectively define first and second farthermost areas which are spaced apart from each other by a first length along the centerline, and respectively define first and second tangential areas which are offset from the centerline. The first and second tangential areas are spaced apart from each other by a distance that, when projected on a longitudinal line in the longitudinal direction, is equivalent to a second length. 
     First and second electrically conductive rollable bodies are respectively rollable on the first and second rolling surfaces about first and second rolling axes, and respectively have first and second perimetrical areas which are in contact with the first and second rolling surfaces, and first and second widths. Each of the first and second widths is defined by a distance which is between two diametrically opposite points in a respective one of the first and second perimetrical areas. Sum of the first width and the second width is smaller than the first length and larger than the sum of the second length and the third length. As such, when the support on which the housing is mounted stands still, the first and second electrically conductive rollable bodies are tangent to each other, and respectively abut against the first and second tangential areas by virtue of gravity, thereby establishing electric contact between the first and second electric contact bodies. Once the support is caused to quiver in an unsteady state, the first and second electrically conductive rollable bodies will be caused to lurch towards one of the first and second farthermost areas so that one of the first and second electrically conductive rollable bodies is out of contact with a corresponding one of the first and second rolling surfaces which defines the other one of said first and second farthermost areas, thereby breaking the electric contact between the first and second electric contact bodies. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments of the invention, with reference to the accompanying drawings, in which: 
     FIG. 1 is an exploded perspective view of a conventional vibration switch; 
     FIGS. 2 and 3 are sectional views of the conventional vibration switch in switch-off and switch-on states, respectively; 
     FIG. 4 is an exploded perspective view of the first preferred embodiment of a vibration switch according to this invention; 
     FIG. 5 is a fragmentary perspective view of the first preferred embodiment; 
     FIGS. 6 and 7 are sectional views of the first preferred embodiment in switch-on and switch-off states, respectively; 
     FIG. 8 is an exploded perspective view of the second preferred embodiment of a vibration switch according to this invention; 
     FIG. 9 is a fragmentary perspective view of the second preferred embodiment; 
     FIGS. 10 and 11 are sectional views of the second preferred embodiment in switch-on and switch-off states, respectively; 
     FIG. 12 is an exploded perspective view of the third preferred embodiment of a vibration switch according to this invention; 
     FIGS. 13 and 14 are sectional views of the third preferred embodiment in switch-on and switch-off states, respectively; and 
     FIGS. 15 and 16 are sectional views of the fourth preferred embodiment of a vibration switch according to this invention in switch-on and switch-off states, respectively. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Before the present invention is described in greater detail, it should be noted that same reference numerals have been used to denote like elements throughout the specification. 
     Referring to FIGS. 4 to  6 , the first preferred embodiment of a vibration switch according to the present invention is shown to comprise a housing  2 , first and second electric contact bodies  25 , 3 , first and second electrically conductive rollable bodies  5 , and first and second electric terminals  26 , 32 . 
     The housing  2  is made from an electrically conductive material, and is adapted to be mounted on a support (not shown), such as a circuit board, in an upright direction. The housing  2  has an upper wall  28  and a lower wall  29  spaced apart from each other in the upright direction, a left end portion  22  which is integrally formed with the upper and lower walls  28 , 29 , and a right end portion which is configured as an insulating plug  4  that is fitted into an opening end  21  cooperatively defined by the upper and lower walls  28 , 29 , thereby confining an accommodation chamber  24 . The insulating plug  4  has a through hole  41  formed therethrough in a longitudinal direction transverse to the upright direction. 
     The first electric contact body  25  is integrally formed with the left end portion  22 , and is disposed in the accommodation chamber  24 . The first electric contact body  25  has a first rolling surface  250  which defines a first farthermost area  252  that is disposed proximate to the left endportion  22 , and a first tangential area  251  that is offset from a centerline (C) oriented in the longitudinal direction and that extends to surround the centerline (C) so as to form a first surrounding region. The first rolling surface  250  is configured to be convergent from the first surrounding region to the first farthermost area  252 . In this embodiment, the first rolling surface  250  is hemispherical. 
     The second electric contact body  3  is disposed in the accommodation chamber  24 , and has a second rolling surface  31  which confronts and which is spaced apart from the first rolling surface  250  along the centerline (C). The second rolling surface  31  defines a second farthermost area  312  which is disposed proximate to the insulating plug  4  and which is spaced apart from the first farthermost area  252  by a first length (L 1 ) along the centerline (C), and a second tangential area  311  which is offset from the centerline (C) and which extends to surround the centerline (C) so as to form a second surrounding region. The second rolling surface  31  is configured to be convergent from the second surrounding region to the second farthermost area  312 . In this embodiment, the second rolling surface  31  is hemispherical. Moreover, the first and second surrounding regions of the first and second rolling surfaces  250 , 31  are spaced apart from each other by a distance which, when projected on a longitudinal line (i.e. the centerline (C)) in the longitudinal direction, is equivalent to a second length (L 2 ). 
     The first and second electrically conductive rollable bodies  5  are spherical in shape, are disposed to be rollable on the first and second rolling surfaces  250 , 31  about first and second rolling axes, respectively, and respectively have first and second perimetrical areas. The first and second electrically conductive rollable bodies  5  have first and second widths, respectively, each of which is defined by a distance between two diametrically opposite points in a respective one of the first and second perimetrical areas. In this embodiment, the first and second widths are equal to diameters of the first and second electrically conductive rollable bodies  5 , respectively. Sum (L 3 ) of the first width and the second width is smaller than the first length (L 1 ) and larger than the second length (L 2 ). 
     The first electric terminal  26  is integrally formed with the left end portion  22  of the housing  2 , and has a connected end connected to the first electric contact body  25 , and a terminal end  261  extending from the connected end outwardly and downwardly of the left end portion  22  to be in electric contact with the support. 
     The second electric terminal  32  has a connected end connected to the second electric contact body  3  and extending through the through hole  41  in the insulating plug  4 , and a terminal end  321  that extends from the connected end in the longitudinal direction and outwardly of the insulating plug  4  and that is bent downwardly of the housing  1  to be in electric contact with the support. 
     As such, when the support (not shown) on which the housing  1  is mounted stands still, the first and second electrically conductive rollable bodies  5 , which are tangent to each other, respectively abut against the first and second tangential areas  251 , 311  by virtue of gravity, thereby establishing an electric contact between the first and second electric contact bodies  25 , 3  and making an electrical connection between the first and second electric terminals  26 , 32 , as shown in FIG.  6 . 
     Referring to FIG. 7, once the support is caused to quiver in an unsteady state by a force (F), the first and second electrically conductive rollable bodies  5  will be caused to lurch towards one of the first and second farthermost areas  252 , 312  (the second farthermost area  312  as shown in FIG.  7 ) so that one of the first and second electrically conductive rollable bodies  5  is out of contact with a corresponding one of the first and second rolling surfaces  250 , 31  (the first rolling surface  250  as shown in FIG. 7) that defines the other one of the first and second farthermost areas  252 , 312 , thereby breaking the electric contact between the first and second electric contact bodies  25 , 3 , and the electrical connection between the first and second electric terminals  26 , 32 . 
     As compared with the conventional vibration switch shown in FIGS. 1 to  3 , the vibration switch of this invention has enhanced sensitivity and can be instantly disposed in a switch-off state when jerked by a force coming from any direction. 
     Referring to FIGS. 8 to  10 , the second preferred embodiment of a vibration switch according to this invention is shown to be similar to the first preferred embodiment in construction. In this embodiment, the first and second rolling surfaces  250 , 31  are spaced apart from each other along a centerline (C) which is oriented in the upright direction. That is, the first and second rolling surfaces  250 , 31  are disposed inwardly of the upper and lower walls  28 , 29  of the housing  2 , respectively, and confront each other in the upright direction. Thus, the first and second farthermost areas  252 , 312  are disposed proximate to the upper and lower walls  28 , 29 , respectively. 
     It is noted that the second length (L 2 ) is the sum of a first distance (d 1 ) between the first tangential area  251  and the centerline (C) in terms of the longitudinal direction, and a second distance (d 2 ) between the second tangential area  311  and the centerline (C) in terms of the longitudinal direction. As described in the first preferred embodiment, the third length (L 3 ) is larger that the second length (L 2 ) so as to maintain the contact between the first and second electrically conductive rollable bodies  5  and the first and second tangential areas  252 , 312 , respectively. 
     Furthermore, an insulating plug  4  is fitted into an opening end confined by the lower wall  29  to insulate the lower wall  29  from the second electric contact body  3 . The first electric terminal  26  is integrally formed with the housing  2 , and has a terminal end which extends outwardly and downwardly of the lower wall  29 . 
     As such, referring to FIG. 11, once the support (not shown), on which the housing  2  is mounted, is caused to quiver by a force (F), the second electrically conductive rollable body  5 , which is disposed on the second rolling surface  31 , is caused to lurch towards the second farthermost area  312  such that the first electrically conductive rollable body  5  is out of contact with the first rolling surface  250 , thereby breaking the electrical connection between the first and second electric terminals  26 , 32 . 
     Referring to FIGS. 12 to  14 , the third preferred embodiment of a vibration switch according to this invention is shown to be similar to the first preferred embodiment in construction. In this embodiment, the first electric contact body  7  is configured to be similar to the second electric contact body  3 , and is separable from the housing  6 . An additional insulating plug  4 ′ is provided to be fitted into an opening end  61  of the housing  6  to serve as the left end portion. Furthermore, the first electric terminal  33  is configured to be similar to the second electric terminal  32 , and has a connected end connected to the second electric contact body  7  through a through hole  41 ′ in the insulating plug  4 ′, and a terminal end that extends from the connected end in the longitudinal direction and outwardly of the insulating plug  4  and bent downwardly of the housing  6  to be in electric contact with the support (not shown). 
     FIGS. 15 and 16 show the fourth preferred embodiment of a vibration switch according to this invention. This embodiment is similar to the second preferred embodiment, except that the first electric contact body  9  is configured to be similar to the second electric contact body  3 , and is separable from the housing  8 . An additional insulating plug  4 ″ is provided to be fitted into an opening end of the housing  8 . Furthermore, the first electric terminal  34  is similar to the second electric terminal  32 , and has a connected end connected to the second electric contact body  9  through a through hole  41 ″ in the insulating plug  4 ″, and a terminal end extending from the connected end in the upright direction and outwardly of the insulating plug  4 ″. 
     While the present invention has been described in connection with what is considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretations and equivalent arrangements.