Patent Publication Number: US-8969747-B2

Title: Sandwich-type tilt switch

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a tilt switch, more particularly to a sandwich-type tilt switch that uses angular changes to open or close a circuit. 
     2. Description of the Related Art 
     Referring to  FIGS. 1 and 2 , a tilt switch  1 , as disclosed in Taiwanese Patent No. M409517, includes an insulated housing  11 , a cover  12  that mates with the insulated housing  11  and that cooperates with the same to define an accommodation chamber  10 , four terminals  13 , and a ball  14  disposed in the accommodation chamber  10 . The insulated housing  11  has a plurality of engaging pegs  111  projecting from an upper surface thereof, and a plurality of accommodating grooves  112  and a plurality of pinholes  113  formed in a lower wall of the insulated housing  11  that allow spatial communication between the accommodation chamber  10  and an exterior of the insulated housing  11 . The cover  12  has a plurality of openings  121  for extension of the respective engaging pegs  111  therethrough. Each of the terminals  13  has a contact portion  131  that extends through a respective accommodating groove  112  into the accommodation chamber  10 , and a welding portion  132  exposed to the exterior of the insulated housing  11 . 
     This structure allows the ball  14  to roll between a closed circuit state, in which the ball  14  simultaneously bridges any two of the contact portions  131 , and an open circuit state, in which the ball does not simultaneously bridge two of the contact portions  131 . Hence, an ON/OFF effect of the tilt switch  1  can be achieved. 
     The pin holes  113  respectively accommodating a plurality of positioning pegs  15  are formed in the lower wall of the insulated housing  11  of the tilt switch  1  when forming the insulated housing  11  by injection molding. To facilitate the injection molding of the insulated housing  11 , the positioning pins  15  are disposed to respectively abut against the terminals  13  to stabilize the terminals  13 . However, gaps that permit penetration of moisture are formed between the pin holes  113  and the respective receiving grooves  112 . Further, because the positioning pins  15  merely abut against the terminals  13  and do not secure the positions of the terminals  13 , the terminals  13  may easily shift during the injection molding process, thereby causing formation anomalies that may reduce assembly precision. 
     SUMMARY OF THE INVENTION 
     Therefore, the object of the present invention is to provide a sandwich-type tilt switch with enhanced stability and positioning effect. 
     Accordingly, a tilt switch of the present invention comprises an insulated housing, a plurality of conductive terminals, and a conductive body. The insulated housing includes two housing halves that cooperatively define an accommodation chamber and that have opposed joined surfaces joined together around said accommodation chamber, and a plurality of positioning grooves formed in the joined surface of at least one of the housing halves around the accommodation chamber. The conductive terminals are sandwiched between the housing halves. Each of the conductive terminals has a plate member positioned in a respective one of the positioning grooves, a contact portion extending from the plate member into the accommodation chamber, and a conducting portion exposed to an exterior of the insulated housing. The plate member has a plate body and two connecting pins formed on different sides of the plate body. One of the connecting pins extends from one side of the plate body and is connected to the conducting portion. The conductive body is disposed in the accommodation chamber and is movable between a closed circuit state, in which the conductive body bridges the contact portions of at least two of the conductive terminals, and an open circuit state, in which the conductive body does not bridge the contact portions of any two of the conductive terminals. 
     The beneficial effect of the present invention resides in that by using the positioning grooves to restrict the positions of the respective conductive terminals, the positioning effect of the conductive terminals before assembly and the stability of the conductive terminals after assembly can be enhanced, thereby facilitating the assembly process and enhancing assembly precision. 
    
    
     
       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 with reference to the accompanying drawings, of which: 
         FIG. 1  is an exploded perspective view of a tilt switch disclosed in Taiwanese Patent No. M409517; 
         FIG. 2  is a sectional view of the tilt switch of  FIG. 1  in an assembled state; 
         FIG. 3  is an exploded perspective view of the first preferred embodiment of a tilt switch according to the present invention; 
         FIG. 4  is a view similar to  FIG. 3 , but with a plurality of conductive terminals being respectively disposed in positioning grooves of a housing half; 
         FIG. 5  is a perspective view of the first preferred embodiment in an assembled state; 
         FIG. 6  is a sectional view of the first preferred embodiment taken along line VI-VI of  FIG. 5 ; 
         FIG. 7  is a sectional top view of the first preferred embodiment, illustrating a conductive body in contact with contact portions of two conductive terminals; and 
         FIG. 8  is a sectional view of a tilt switch according to the second preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Before the present invention is described in greater detail, it should be noted that like elements are denoted by the same reference numerals throughout the disclosure. 
     Referring to  FIGS. 3 ,  4 , and  5 , the first preferred embodiment of a sandwich-type tilt switch according to the present invention comprises an insulated housing  2 , a plurality of conductive terminals  3 , and a conductive body  4 . 
     The insulated housing  2  includes two housing halves  21  that cooperatively define an accommodation chamber  20  and that have opposite joined surfaces  211  joined together along an axis (X) and around the accommodation chamber  20 , a plurality of positioning grooves  22 , a plurality of protruding portions  23 , a plurality of recess portions  24 , and two concavities  25 . In this embodiment, each of the housing halves  21  has an inner surface  212  that cooperates with the inner surface  212  of the other housing half  21  to form the accommodation chamber  20 , and includes four positioning grooves  22  formed in the joined surface  211  of a respective one of the housing halves  21  around the accommodation chamber  20 , and two protruding portions  23  and two recess portions  24  that are formed in the joined surface  211  of the respective housing half  21 . Each of the concavities  25  is formed in the inner surface  212  of the respective housing half  21 . Each of the positioning grooves  22  has two openings  221 ,  222  that are formed in different sides of the corresponding housing half  21  and that are in spatial communication with an exterior of the insulated housing  2 . The protruding portions  23  and the recess portions  24  of one of the housing halves  21  are configured to respectively mate with the recess portions  24  and the protruding portions  23  of the other housing half  21 . Hence, the two housing halves  21  are mated together as a unitary body through interengagement of the recess portions  24  and the protruding portions  23 . In an alternative embodiment, one of the housing halves  21  may include four protruding portions  23 , while the other housing half  21  may include four recess portions  24  to respectively mate with the protruding portion  23 . The protruding portions  23  and the recess portion  24  of each housing half  21  are located within an area of the respective positioning grooves  22 . Each of the protruding portions  23  and the recess portions  24  has a polygonal profile. Each of the protruding portions  23  takes the form of a rectangular column in this embodiment. Alternatively, each protruding portion  23  may take the form of a rib or a projection. Each of the recess portions  24  takes the form of a rectangular groove in this embodiment. Alternatively, each recess portion  24  may take the form of a hole or a notch. 
     The conductive terminals  3  are sandwiched between the two housing halves  21 . Each of the conductive terminals  3  has a plate member  31  positioned in a respective positioning groove  22  in one of the housing halves  21 , a contact portion  32  extending from the plate member  31  into the accommodation chamber  20 , and a conducting portion  33  exposed to the exterior of the insulated housing  2 . The plate member  31  has a plate body  311 , two connecting pins  312 ,  313  extending from different sides of the plate body  311 , and a through hole  314  formed in the plate body  311  for extension of the respective protruding portion  23  therethrough. The plate body  311  of each plate member  31  is received in the respective positioning groove  22  such that the connecting pins  312 ,  313  of each plate member  31  are respectively exposed through the openings  221 ,  222  in the corresponding positioning groove  22 . In this embodiment, the through hole  314  is a rectangular hole that penetrates the plate body  311  in a direction parallel to the axis (X). The conducting portion  33  of each conductive terminal  3  is connected to the connecting pin  312  of a respective plate member  31 . 
     The conductive body  4  is received in the accommodation chamber  20  and is movable between a closed circuit state, in which the conductive body  4  bridges the contact portions  32  of at least two of the conductive terminals  3 , and an open circuit state, in which the conductive body  4  does not bridge the contact portions  32  of any two of the conductive terminals  3 . 
     During assembly, the plate member  31  of each conductive terminal  3  is merely pressed into a respective positioning groove  22  in one of the housing halves  21 , and the plate member  31  and the corresponding connecting pins  312 ,  312  can be positioned in the respective positioning groove  22  and the corresponding openings  221 ,  222 . As such, any offsetting of the conductive terminals  3  can be prevented, thereby stabilizing the conductive terminals  3  on the joined surface  211  of the one of the housing halves  21 . When the two housing halves  21  are joined together, not only can the two housing halves  21  be joined together as a unitary body through the interengagement of the protruding portions  23  and the recess portions  24 , the protruding portions  23  of the housing halves  21  can also pass through the through holes  314  in the respective conductive terminals  3 , thereby sandwiching the conductive terminals  3  between the joined housing halves  21 . 
     It is worth mentioning that a plurality of conductive terminals  3  may be manufactured simultaneously by pressing a blank strip such that the connecting pins  313  join the plurality of conductive terminals  3 . This allows the simultaneous pressing of a plurality of conductive terminals  3  with a plurality of housing halves  21 , thereby increasing the speed of assembly. 
     With reference to  FIGS. 4 and 6 , at a default position, the conductive body  3  falls into the concavity  25  and is located in the open circuit state. At this time, the conductive body  4  does not contact any of the contact portions  32  of the conductive terminals  3 , and the tilt switch is at an “OFF” state. 
     With reference to  FIGS. 4 and 7 , when the insulated housing  2  is tilted due to an external force, the conductive body  3  will roll within the accommodation chamber  4  based on the direction of the external force into the closed circuit state, in which the conductive body  4  contacts and bridges the contact portions  32  of two of the conductive terminals  3 , thereby shifting the tilt switch from an “OFF” state to an “ON” state. Thus, ON/OFF effect of the tilt switch can be achieved. 
     With reference to  FIG. 8 , the second preferred embodiment of a tilt switch according to the present invention is shown to be substantially similar to the first preferred embodiment. However, in this embodiment, the insulated housing  2  includes two bulge portions  26  in place of the concavities  25  (see  FIG. 6 ). Each of the bulge portions  26  protrudes from the inner surface  212  of the respective housing half  21  toward the accommodation chamber  20 . In the absence of an external force, the conductive body  4  is pushed by the bulge portion  26  to move to the closed circuit state, in which the conductive body  4  contacts and bridges the contact portions  32  of two of the conductive terminals  3 . When the insulated housing  2  is vibrated or is tilted due to an external force, the conductive body  4  is moved to the open circuit state, in which the conductive body  4  will not contact any of the contact portions  32  of the conductive terminals  3 . 
     In sum, because the conductive terminals  3  are sandwiched between the housing halves  21  of the insulated housing  2 , the insulated housing  2  of the present invention improves upon the prior art by negating the need for additional openings or positioning pins  15  (see  FIG. 2 ). This invention only needs to use the protruding portions  23  and the recess portions  24  to limit the position of the conductive terminals  3 , and the positioning effect of the conductive terminals  3  prior to assembly and the stability of the conductive terminals  3  after assembly can thus be enhanced, thereby facilitating the assembly process and enhancing assembly precision. 
     While the present invention has been described in connection with what are 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 interpretation so as to encompass all such modifications and equivalent arrangements.