Abstract:
An omni-directional tilt and vibration sensor contains a first electrically conductive element, a second electrically conductive element, and an electrically insulative element. The electrically insulative element is connected to the first electrically conductive element and the second electrically conductive element, where at least a portion of the first electrically conductive element and at least a portion of the second electrically conductive element are located within the electrically insulative element. A plurality of electrically conductive weights are located within a cavity of the sensor, wherein the cavity is defined by at least one surface of the first electrically conductive element, at least one surface of the electrically insulative element, and at least one surface of the second electrically conductive element.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   The present application is a continuation-in-part of U.S. patent application Ser. No. 11/037,497, filed Jan. 18, 2005, now U.S. Pat. No. 7,067,748 and having the title “OMNIDIRECTIONAL TILT AND VIBRATION SENSOR,” the entire disclosure of which is incorporated wherein by reference. 

   FIELD OF THE INVENTION 
   The present invention is generally related to sensors, and more particularly is related to an omnidirectional tilt and vibration sensor. 
   BACKGROUND OF THE INVENTION 
   Many different electrical tilt and vibration switches are presently available and known to those having ordinary skill in the art. Typically, tilt switches are used to switch electrical circuits ON and OFF depending on an angle of inclination of the tilt switch. These types of tilt switches typically contain a free moving conductive element located within the switch, where the conductive element contacts two terminals when the conductive element is moved into a specific position, thereby completing a conductive path. An example of this type of tilt switch is a mercury switch. Unfortunately, it has been proven that use of Mercury may lead to environmental concerns, thereby leading to regulation on Mercury use and increased cost of Mercury containing products, including switches. 
   To replace Mercury switches, newer switches use a conductive element capable of moving freely within a confined area. A popularly used conductive element is a single metallic ball. Tilt switches having a single metallic ball are capable of turning ON and OFF in accordance with a tilt angle of the tilt switch. Certain tilt switches also contain a ridge, a bump, or a recess, that prevents movement of the single metallic ball from a closed position (ON) to an open position (OFF) unless the tilt angle of the tilt switch is in excess of a predetermined angle. 
   An example of a tilt switch requiring exceeding of a tilt angle of the tilt switch is provided by US. Pat. No. 5,136,157, issued to Blair on Aug. 4, 1992 (hereafter, the &#39;157 patent). The &#39;157 patent discloses a tilt switch having a metallic ball and two conductive end pieces separated by a non-conductive element. The two conductive end pieces each have two support edges. A first support edge of the first conductive end piece and a first support edge of the second conductive end piece support the metallic ball there-between, thereby maintaining electrical communication between the first conductive end piece and the second conductive end piece. Maintaining electrical communication between the first conductive end piece and the second conductive end piece keeps the tilt switch in a closed position (ON). To change the tilt switch into an open position (OFF), the metallic ball is required to be moved so that the metallic ball is not connected to both the first conductive end piece and the second conductive end piece. Therefore, changing the tilt switch into an open position (OFF) requires tilting of the &#39;157 patent tilt switch past a predefined tilt angle, thereby removing the metallic ball from location between the first and second conductive end piece. Unfortunately, tilt switches generally are not useful in detecting minimal motion, regardless of the tilt angle. 
   Referring to vibration switches, typically a vibration switch will have a multitude of components that are used to maintain at least one conductive element in a position providing electrical communication between a first conductive end piece and a second conductive end piece. An example of a vibration switch having a multitude of components is provided by U.S. Pat. No. 6,706,979 issued to Chou on Mar. 16, 2004 (hereafter, the &#39;979 patent). In one embodiment of Chou, the &#39;979 patent discloses a vibration switch having a conductive housing containing an upper wall, a lower wall, and a first electric contact body. The upper wall and the lower wall of the conductive housing define an accommodation chamber. The conductive housing contains an electrical terminal connected to the first electric contact body for allowing electricity to traverse the housing. A second electric contact body, which is separate from the conductive housing, is situated between the upper wall and lower wall of the conductive housing (i.e., within the accommodation chamber). The second electric contact body is maintained in position within the accommodation chamber by an insulating plug having a through hole for allowing an electrical terminal to fit therein. 
   Both the first electrical contact body and the second electrical contact body are concave in shape to allow a first and a second conductive ball to move thereon. Specifically, the conductive balls are adjacently located within the accommodation chamber with the first and second electric contact bodies. Due to gravity, the &#39;979 patent first embodiment vibration switch is typically in a closed position (ON), where electrical communication is maintained from the first electrical contact body, to the first and second conductive balls, to the second electrical contact body, and finally to the electrical terminal. 
   In an alternative embodiment, the &#39;979 patent discloses a vibration switch that differs from the vibration switch of the above embodiment by having the first electrical contact body separate from the conductive housing, yet still entirely located between the upper and lower walls of the housing, and an additional insulating plug, through hole and electrical terminal. Unfortunately, the many portions of the &#39;979 patent vibration switch results in more time required for assembly, in addition to higher cost. 
   Thus, a heretofore unaddressed need exists in the industry to address the aforementioned deficiencies and inadequacies. 
   SUMMARY OF THE INVENTION 
   Embodiments of the present invention provide an omnidirectional tilt and vibration sensor and a method of construction thereof. Briefly described, in architecture, one embodiment of the system, among others, can be implemented as follows. The sensor contains a first electrically conductive element, a second electrically conductive element, and an electrically insulative element. The electrically insulative element is connected to the first electrically conductive element and the second electrically conductive element, where at least a portion of the first electrically conductive element and at least a portion of the second electrically conductive element are located within the electrically insulative element. A plurality of electrically conductive weights are located within a cavity of the sensor, wherein the cavity is defined by at least one surface of the first electrically conductive element, at least one surface of the electrically insulative element, and at least one surface of the second electrically conductive element. 
   The present invention can also be viewed as providing methods for assembling the omnidirectional tilt and vibration sensor having a first electrically conductive element, a second electrically conductive element, an electrically insulative element, and a plurality of electrically conductive weights. In this regard, one embodiment of such a method, among others, can be broadly summarized by the following steps: fitting a distal portion of the first electrically conductive element within a hollow center of the electrically insulative member, wherein a proximate portion of the first electrically conductive element remains external to the hollow center of the electrically insulative member; positioning the plurality of electrically conductive weights within the hollow center of the electrically insulative member; and fitting a distal portion of the second electrically conductive element within the hollow center of the electrically insulative member, wherein a proximate portion of the second electrically conductive element remains external to the hollow center of the electrically insulative member. 
   Other systems, methods, features, and advantages of the present invention will be or will become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Many aspects of the invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
       FIG. 1  is an exploded perspective side view of the present omnidirectional tilt and vibration sensor, in accordance with a first exemplary embodiment of the invention. 
       FIG. 2  is a cross-sectional side view of the first end cap of  FIG. 1 . 
       FIG. 3  is a cross-sectional side view of the central member of  FIG. 1 . 
       FIG. 4  is a cross-sectional side view of the second end cap of  FIG. 1 . 
       FIG. 5  is a flowchart illustrating a method of assembling the omnidirectional tilt and vibration sensor of  FIG. 1 . 
       FIG. 6A  and  FIG. 6B  are cross-sectional side views of the sensor of  FIG. 1  in a closed state, in accordance with the first exemplary embodiment of the invention. 
       FIGS. 7A ,  7 B,  7 C, and  7 D are cross-sectional side views of the sensor of  FIG. 1  in an open state, in accordance with the first exemplary embodiment of the invention. 
       FIG. 8  is a cross-sectional side view of the present omnidirectional tilt and vibration sensor, in accordance with a second exemplary embodiment of the invention. 
       FIG. 9  is cross-sectional view of a sensor in a closed state, in accordance with a third exemplary embodiment of the invention. 
       FIG. 10  is a cross-sectional side view of a central member of a sensor, in accordance with a fourth exemplary embodiment of the invention. 
       FIG. 11  is a cross-sectional side view of the sensor of which the central member of  FIG. 10  is a part, in accordance with the fourth exemplary embodiment of the invention. 
       FIG. 12A  is a cross-sectional side view of an omnidirectional tilt and vibration sensor, in accordance with a fifth exemplary embodiment of the invention, where the sensor is in an open state. 
       FIG. 12B  is a cross-sectional side view of the omnidirectional tilt and vibration sensor of  FIG. 12A , in accordance with an alternative embodiment of the invention. 
       FIG. 13  is a cross-sectional side view of the first end cap of the sensor of  FIG. 12A . 
       FIG. 14  is a cross-sectional view of the omnidirectional tilt and vibration sensor of  FIG. 12A , where the sensor is in a closed state. 
       FIG. 15A  and  FIG. 15B  are cross-sectional side views of the present omnidirectional tilt and vibration sensor, in accordance with a sixth exemplary embodiment of the invention. 
   

   DETAILED DESCRIPTION 
   The following describes an omnidirectional tilt and vibration sensor. The sensor contains a minimal number of cooperating parts to ensure ease of assembly and use.  FIG. 1  is an exploded perspective side view of the present omnidirectional tilt and vibration sensor  100  (hereafter, “the sensor  100 ”), in accordance with a first exemplary embodiment of the invention. 
   Referring to  FIG. 1 , the sensor  100  contains a first end cap  110 , a central member  140 , a second end cap  160 , and multiple weights embodied as a pair of conductive balls  190  that are spherical in shape (hereafter, conductive spheres). The first end cap  110  is conductive, having a proximate portion  112  and a distal portion  122 . Specifically, the first end cap  110  may be constructed from a composite of high conductivity and/or low reactivity metals, a conductive plastic, or any other conductive material. 
     FIG. 2  is a cross-sectional side view of the first end cap  110  which may be referred to for a better understanding of the location of portions of the first end cap  110 . The proximate portion  112  of the first end cap  110  is circular, having a diameter D 1 , and having a flat end surface  114 . A top surface  116  of the proximate portion  112  runs perpendicular to the flat end surface  114 . A width of the top surface  116  is the same width as a width of the entire proximate portion  112  of the first end cap  110 . The proximate portion  112  also contains an internal surface  118  located on a side of the proximate portion  112  that is opposite to the flat end surface  114 , where the top surface  116  runs perpendicular to the internal surface  118 . Therefore, the proximate portion  112  is in the shape of a disk. The disk shape of the first end cap  110  is also referred to herein as a flange of the first end cap  110 . 
   It should be noted that while  FIG. 2  illustrates the proximate portion  112  of the first end cap  110  having a flat end surface  114  and the proximate portion  162  ( FIG. 4 ) of the second end cap  160  having a flat surface  164  ( FIG. 4 ), one having ordinary skill in the art would appreciate that the proximate portions  112 ,  162  ( FIG. 4 ) do not require presence of a flat end surface. Instead, the flat end surfaces  114 ,  164  may be convex or concave. In addition, instead of being circular, the first end cap  110  and the second end cap  160  may be square-like in shape, or they may be any other shape. Use of circular end caps  110 ,  160  is merely provided for exemplary purposes. The main function of the end caps  110 ,  160  is to provide a connection to allow an electrical charge introduced to the first end cap  110  to traverse the conductive spheres  190  and be received by the second end cap  160 , therefore, many different shapes and sizes of end caps  110 ,  160  may be used as long as the conductive path is maintained. 
   The relationship between the top portion  116 , the flat end surface  114 , and the internal surface  118  described herein is provided for exemplary purposes. Alternatively, the flat end surface  114  and the internal surface  118  may have rounded or otherwise contoured ends resulting in the top surface  116  of the proximate portion  112  being a natural rounded progression of the end surface  114  and the internal surface  118 . 
   The distal portion  122  of the first end cap  110  is tube-like in shape, having a diameter D 2  that is smaller than the diameter D 1  of the proximate portion  112 . The distal portion  122  of the first end cap  110  contains a top surface  124  and a bottom surface  126 . The bottom surface  126  of the distal portion  122  defines an exterior portion of a cylindrical gap  128  located central to the distal portion  122  of the first end cap  110 . A diameter D 3  of the cylindrical gap  128  is smaller than the diameter D 2  of the distal portion  122 . 
   Progression from the proximate portion  112  of the first end cap  110  to the distal portion  122  of the first end cap  110  is defined by a step where a top portion of the step is defined by the top surface  116  of the proximate portion  112 , a middle portion of the step is defined by the internal surface  118  of the proximate portion  112 , and a bottom portion of the step is defined by the top surface  124  of the distal portion  122 . 
   The distal portion  122  of the first end cap  110  also contains an outer surface  130  that joins the top surface  124  and the bottom surface  126 . It should be noted that while  FIG. 2  shows the cross-section of the outer surface  130  as being squared to the top surface  124  and the bottom surface  126 , the outer surface  130  may instead be rounded or of a different shape. 
   As is better shown by  FIG. 2 , the distal portion  122  of the first end cap  110  is an extension of the proximate portion  112  of the first end cap  110 . In addition, the top surface  124 , the outer surface  130 , and the bottom surface  126  of the distal portion  122  form a cylindrical lip of the first end cap  110 . As is also shown by  FIG. 2 , the distal portion  122  of the first end cap  110  also contains an inner surface  132 , the diameter of which is equal to or smaller than the diameter D 3  of the cylindrical gap  128 . While  FIG. 2  illustrates the inner surface  132  as running parallel to the flat end surface  114 , as is noted hereafter, the inner surface  132  may instead be concave, conical, or hemispherical. 
   Referring to  FIG. 1 , the central member  140  of the sensor  100  is tube-like in shape, having a top surface  142 , a proximate surface  144 , a bottom surface  146 , and a distal surface  148 .  FIG. 3  is a cross-sectional side view of the central member  140  and may also be referred to for a better understanding of the location of portions of the central member  140 . It should be noted that the central member  140  need not be tube-like in shape. Alternatively, the central member  140  may have a different shape, such as, but not limited to that of a square. 
   The bottom surface  146  of the central member  140  defines a hollow center  150  having a diameter D 4  that is just slightly larger than the diameter D 2  ( FIG. 2 ), thereby allowing the distal portion  122  of the first end cap  110  to fit within the hollow center  150  of the central member  140  ( FIG. 3 ). In addition, the top surface  142  of the central member  140  defines the outer surface of the central member  140  where the central member  140  has a diameter D 5 . It should be noted that the diameter D 1  (i.e., the diameter of the proximate portion  112  of the first end cap  110 ) is preferably slightly larger than diameter D 5  (i.e., the diameter of the central member  140 ). Of course, different dimensions of the central member  140  and end caps  110 ,  160  may also be provided. In addition, when the sensor  100  is assembled, the proximate surface  144  of the central member  140  rests against the internal surface  118  of the first end cap  110 . 
   Unlike the first end cap  110  and the second end cap  160 , the central member  140  is not electrically conductive. As an example, the central member  140  may be made of plastic, glass, or any other nonconductive material. In an alternative embodiment of the invention, the central member  140  may also be constructed of a material having a high melting point that is above that used by commonly used soldering materials. As is further explained in detail below, having the central member  140  non-conductive ensures that the electrical conductivity provided by the sensor  100  is provided through use of the conductive spheres  190 . Specifically, location of the central member  140  between the first end cap  110  and the second end cap  160  provides a non-conductive gap between the first end cap  110  and the second end cap  160 . 
   Referring to  FIG. 1 , the second end cap  160  is conductive, having a proximate portion  162  and a distal portion  172 . Specifically, the second end cap  160  may be constructed from a composite of high conductivity and/or low reactivity metals, a conductive plastic, or any other conductive material. 
     FIG. 4  is a cross-sectional side view of the second end cap  160  which may be referred to for a better understanding of the location of portions of the second end cap  160 . The proximate portion  162  of the second end cap  160  is circular, having a diameter D 6 , and having a flat end surface  164 . A top surface  166  of the proximate portion  162  runs perpendicular to the flat end surface  164 . A width of the top surface  166  is the same width as a width of the entire proximate portion  162  of the second end cap  160 . The proximate portion  162  also contains an internal surface  168  located on a side of the proximate portion  162  that is opposite to the flat end surface  164 , where the top surface  166  runs perpendicular to the internal surface  168 . Therefore, the proximate portion  162  is in the shape of a disk. The disk shape of the second end cap  160  is also referred to herein as a flange of the second end cap  160 . 
   The relationship between the top portion  166 , the flat end surface  164 , and the internal surface  168  described herein is provided for exemplary purposes. Alternatively, the flat end surface  164  and the internal surface  168  may have rounded or otherwise contoured ends resulting in the top surface  166  of the proximate portion  162  being a natural rounded progression of the end surface  164  and the internal surface  168 . 
   The distal portion  172  of the second end cap  160  is tube-like is shape, having a diameter D 7  that is smaller than the diameter D 6  of the proximate portion  162 . The distal portion  172  of the second end cap  160  contains a top surface  174  and a bottom surface  176 . The bottom surface  176  of the distal portion  172  defines an exterior portion of a cylindrical gap  178  located central to the distal portion  172  of the second end cap  160 . A diameter D 8  of the cylindrical gap  178  is smaller than the diameter D 7  of the distal portion  172 . 
   Progression from the proximate portion  162  of the second end cap  160  to the distal portion  172  of the second end cap  160  is defined by a step where a top portion of the step is defined by the top surface  166  of the proximate portion  162 , a middle portion of the step is defined by the internal surface  168  of the proximate portion  162 , and a bottom portion of the step is defined by the top surface  174  of the distal portion  172 . 
   The distal portion  172  of the second end cap  160  also contains an outer surface  180  that joins the top surface  174  and the bottom surface  176 . It should be noted that while  FIG. 4  shows the cross-section of the outer surface  180  as being squared to the top surface  174  and the bottom surface  176 , the outer surface  180  may instead be rounded or of a different shape. 
   As is better shown by  FIG. 4 , the distal portion  172  of the second end cap  160  is an extension of the proximate portion  162  of the second end cap  160 . In addition, the top surface  174 , the outer surface  180 , and the bottom surface  176  of the distal portion  172  form a cylindrical lip of the second end cap  160 . As is also shown by  FIG. 4 , the distal portion  172  of the second end cap  160  also contains an inner surface  182 , the diameter of which is equal to or smaller than the diameter D 8  of the cylindrical gap  178 . While  FIG. 4  illustrates the inner surface  182  as running parallel to the flat end surface  164 , the inner surface  182  may instead be concave, conical, or hemispherical. 
   It should be noted that dimensions of the second end cap  160  are preferably the same as dimensions of the first end cap  110 . Therefore, the diameter D 4  of the central member  140  hollow center  150  is also just slightly larger that the diameter D 7  of the second end cap  160 , thereby allowing the distal portion  172  of the second end cap  160  to fit within the hollow center  150  of the central member  140 . In addition, the diameter D 6  (i.e., the diameter of the proximate portion  162  of the second end cap  160 ) is preferably slightly larger that diameter D 5  (i.e., the diameter of the central member  140 ). Further, when the sensor  100  is assembled, the distal surface  148  of the central member  140  rests against the internal surface  168  of the second end cap  160 . 
   Referring to  FIG. 1 , the pair of conductive spheres  190 , including a first conductive sphere  192  and a second conductive sphere  194 , fit within the central member  140 , within a portion of the cylindrical gap  128  of the first distal portion  122  of the first end cap  110 , and within a portion of the cylindrical gap  178  of the second end cap  160 . Specifically, the inner surface  132 , bottom surface  126 , and outer surface  130  of the first end cap  110 , the bottom surface  146  of the central member  140 , and the inner surface  182 , bottom surface  176 , and outer surface  180  of the second end cap  160  form a central cavity  200  of the sensor  100  where the pair of conductive spheres  190  are confined. 
   Further illustration of location of the conductive spheres  190  is provided and illustrated with regard to  FIGS. 6A ,  6 B, and  7 A- 7 D. It should be noted that, while the figures in the present disclosure illustrate both of the conductive spheres  190  as being substantially symmetrical, alternatively, one sphere may be larger that the other sphere. Specifically, as long as the conductive relationships described herein are maintained, the conductive relationships may be maintained by both spheres being larger, one sphere being larger than the other, both spheres being smaller, or one sphere being smaller. It should be noted that the conductive spheres  190  may instead be in the shape of ovals, cylinders, or any other shape that permits motion within the central cavity in a manner similar to that described herein. 
   Due to minimal components, assembly of the sensor  100  is quite simplistic. Specifically, there are four components, namely, the first end cap  10 , the central member  140 , the conductive spheres  190 , and the second end cap  160 .  FIG. 5  is a flowchart illustrating a method of assembling the omnidirectional tilt and vibration sensor  100  of  FIG. 1 . It should be noted that any process descriptions or blocks in flowcharts should be understood as representing modules, segments, portions of code, or steps that include one or more instructions for implementing specific logical functions in the process, and alternate implementations are included within the scope of the present invention in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present invention. 
   As is shown by block  202 , the distal portion  122  of the first end cap  110  is fitted within the hollow center  150  of the central member  140  so that the proximate surface  144  of the central member  140  is adjacent to or touching the internal surface  118  of the first end cap  110 . The conductive spheres  190  are then positioned within the hollow center  150  of the central member  140  and within a portion of the cylindrical gap  128  (block  204 ). The distal portion  172  of the second end cap  160  is then fitted within the hollow center  150  of the central member  140 , so that the distal surface  148  of the central member  140  is adjacent to or touching the internal surface  168  of the second end cap  160  (block  206 ). 
   In accordance with an alternative embodiment of the invention, the sensor  100  may be assembled in an inert gas, thereby creating an inert environment within the central cavity  200 , thereby reducing the likelihood that the conductive spheres  190  will oxidize. As is known by those having ordinary skill in the art, oxidizing of the conductive spheres  190  would lead to a decrease in the conductive properties of the conductive spheres  190 . In addition, in accordance with another alternative embodiment of the invention, the first end cap  110 , the central member  140 , and the second end cap  160  may be joined by a hermetic seal, thereby preventing any contaminant from entering the central cavity  200 . 
   The sensor  100  has the capability of being in a closed state or an open state, depending on location of the conductive spheres  190  within the central cavity  200  of the sensor  100 .  FIG. 6A  and  FIG. 6B  are cross-sectional views of the sensor  100  of  FIG. 1  in a closed state, in accordance with the first exemplary embodiment of the invention. In order for the sensor  100  to be maintained in a closed state, an electrical charge introduced to the first end cap  110  is required to traverse the conductive spheres  190  and be received by the second end cap  160 . 
   Referring to  FIG. 6A , the sensor  100  is in a closed state because the first conductive sphere  192  is touching the bottom surface  126  of the first end cap  110 , the conductive spheres  192 ,  194  are touching, and the second conductive sphere  194  is touching the bottom surface  176  and inner surface  182  of the second end cap  162 , thereby providing a conductive path from the first end cap  110 , through the conductive spheres  190 , to the second end cap  160 . Referring to  FIG. 6B , the sensor  100  is in a closed state because the first conductive sphere  192  is touching the bottom surface  126  and inner surface  132  of the first end cap  110 , the conductive spheres  192 ,  194  are touching, and the second conductive sphere  194  is touching the bottom surface  176  of the second end cap  162 , thereby providing a conductive path from the first end cap  110 , through the conductive spheres  190 , to the second end cap  160 . Of course, other arrangements of the first and second conductive spheres  190  within the central cavity  200  of the sensor  100  may be provided as long as the conductive path from the first end cap  110  to the conductive spheres  190 , to the second end cap  160  is maintained. 
     FIGS. 7A-FIG .  7 D are cross-sectional views of the sensor  100  of  FIG. 1  in an open state, in accordance with the first exemplary embodiment of the invention. In order for the sensor  100  to be maintained in an open OFF state, an electrical charge introduced to the first end cap  110  cannot traverse the conductive spheres  190  and be received by the second end cap  160 . Referring to  FIGS. 7A-7D , each of the sensors  100  displayed are in an open state because the first conductive sphere  192  is not in contact with the second conductive sphere  194 . Of course, other arrangements of the first and second conductive spheres  190  within the central cavity  200  of the sensor  100  may be provided as long as no conductive path is provided from the first end cap  110  to the conductive spheres  190 , to the second end cap  160 . 
     FIG. 8  is a cross-sectional side view of the present omnidirectional tilt and vibration sensor  300 , in accordance with a second exemplary embodiment of the invention. The sensor  300  of the second exemplary embodiment of the invention contains a first nub  302  located on the flat end surface  114  of the first end cap  110  and a second nub  304  located on a flat end surface  164  of the second end cap  160 . The nubs  302 ,  304  provide a conductive mechanism for allowing the sensor  300  to connect to a printed circuit board (PCB) landing pad, where the PCB landing pad has an opening cut into it allowing the sensor to recess into the opening. Specifically, dimensions of the sensor in accordance with the first exemplary embodiment and the second exemplary embodiment of the invention may be selected so as to allow the sensor to fit within a landing pad of a PCB. Within the landing pad there may be a first terminal and a second terminal. By using the nubs  302 ,  304 , fitting the sensor  300  into landing pad may press the first nub  302  against the first terminal and the second nub  304  against the second terminal. Those having ordinary skill in the art would understand the basic structure of a PCB landing pad, therefore, further explanation of the landing pad is not provided herein. 
   It should be noted that the sensor of the first and second embodiments have the same basic rectangular shape, thereby contributing to ease of preparing a PCB for receiving the sensor  100 ,  300 . Specifically, a hole may be cut in a PCB the size of the sensor  100  (i.e., the size of the first and second end caps  110 ,  160  and the central member  140 ) so that the sensor  100  can drop into the hole, where the sensor is prevented from falling through the hole when caught by the nubs  302 ,  304  that land on connection pads. In the first exemplary embodiment of the invention, where there are no nubs, the end caps  10 ,  160  may be directly mounted to the PCB. 
   In accordance with another alternative embodiment of the invention, the two conductive spheres may be replaced by more than two conductive spheres, or other shapes that are easily inclined to roll when the sensor  100  is moved. 
     FIG. 9  is cross-sectional view of a sensor  400  in a closed state, in accordance with a third exemplary embodiment of the invention. As is shown by  FIG. 9 , an inner surface  412  of a first end cap  410  is concave is shape. In addition, an inner surface  422  of a second end cap  420  is concave in shape. The sensor  400  of  FIG. 9  also contains a first nub  430  and a second nub  432  that function in a manner similar to the nubs  302 ,  304  in the second exemplary embodiment of the invention. Having a sensor  400  with concave inner surfaces  412 ,  422  keeps the sensor  400  in a normally closed state due to the shape of the inner surfaces  412 ,  422  in combination with gravity causing the conductive spheres  192 ,  194  to be drawn together. 
     FIG. 10  is a cross-sectional side view of a central member of a sensor, in accordance with a fourth exemplary embodiment of the invention. Referring to  FIG. 10 , the central member  500  is tube-like in shape, having a top surface  502 , a proximate surface  504 , a bottom surface  506 , and a distal surface  508 . It should be noted that the central member  500  need not be tube-like in shape. Alternatively, the central member  500  may have a different shape, such as, but not limited to, that of a rectangle. 
   The bottom surface  506  of the central member  500  defines a hollow center having a diameter D 4  that is slightly larger than the diameter D 2  ( FIG. 2 ) thereby allowing the distal portion  122  of the first end cap  110  to fit within the hollow center  510  of the central member  500 . In addition, the central member  500  contains an outer lip  550 . A top portion of the outer lip  550  is the top surface  502 . The outer lip  550  also contains an outer lip end surface  552  and an outer lip bottom surface  554 , where the outer lip bottom surface  554  is perpendicular to the outer lip end surface  552 . Of course, the outer lip bottom surface  554  is not required to be perpendicular to the outer lip end surface  552 . 
   The top surface  502  of the central member  500  has a length L 4 , while a length L 2  of the hollow center  510  extends from the proximate surface  504  of the central member  500  to the distal surface  508  of the central member  500 . The outer lip end surface  552  extends a distance ½ (L 4 -L 2 ) from either the proximate surface  504  or from the distal surface  508  of the central member  500 . The distance ½ (L 4 -L 2 ) is the same or larger than the width of the top surface  116  ( FIG. 2 ) of the proximate portion  112  ( FIG. 2 ) of the first end cap  110  ( FIG. 2 ), thereby having the first end cap  110  ( FIG. 2 ) and the second end cap  160  ( FIG. 4 ) within the central member  500 . 
   The bottom surface  506  of the central member  500  defines the hollow center  510  having the diameter D 4  that is slightly larger than the diameter D 2  ( FIG. 2 ), thereby allowing the distal portion  122  of the first end cap  110  to fit within the hollow center  150  of the central member  500 . In addition, the distance between the bottom lip surface  554  of the central member  500  defines a diameter D 8 . It should be noted that the diameter D 1  (i.e., the diameter of the proximate portion  112  ( FIG. 2 ) of the first end cap  110  ( FIG. 2 )) is preferably slightly smaller than diameter D 8 . In addition, a diameter D 6  (i.e., a diameter of the proximate portion  162  ( FIG. 4 ) of the second end cap  160  ( FIG. 4 )) is preferably slightly smaller than diameter D 8 . Of course, different dimensions of the central member  500  and end caps  110 ,  160  may also be provided. In addition, when the tilt sensor  100  is assembled, the proximate surface  504  of the central member  500  rests against the internal surface  118  of the first end cap  110 , and the bottom lip surface  554  of the central member  500  rests against the top surface  116  of the proximate portion  112 . Further, when the tilt sensor  100  is assembled, the distal surface  508  of the central member  500  rests against an internal surface  168  of the second end cap  160 , and the bottom lip surface  554  of the central member  500  rests against the top surface  166  of the proximate portion  162 . 
     FIG. 11  is a cross-sectional side view of a sensor  600  of which the central member of  FIG. 10  is a part, in accordance with the fourth exemplary embodiment of the invention. The sensor  600  is shown in a closed state. 
     FIG. 12A  is a cross-sectional side view of an omnidirectional tilt and vibration sensor  700 , in accordance with a fifth exemplary embodiment of the invention, where the sensor  700  is in an open state. The sensor  700  of  FIG. 12A  does not contain a flange on a first end cap  702  or a flange on a second end cap  750 . The central member  140  of the fifth exemplary embodiment of the invention is the same as the central member  140  of  FIG. 3 , and is therefore, not again described in detail. 
     FIG. 12B  is a cross-sectional side view of the omnidirectional tilt and vibration sensor  700  of  FIG. 12A , in accordance with an alternative embodiment of the invention, where the sensor  700  is in an open state. The sensor  700  does not contain a flange on the first end cap  702  or a flange on the second end cap  750 . In addition, the central member  140  extends over the proximate portion  712  ( FIG. 13 ) and a distal portion  722  ( FIG. 13 ) of the first end cap  702 , and over the proximate portion and the distal portion of the second end cap  750 . 
     FIG. 13  is a cross-sectional side view of the first end cap  702 , which may be referred to for a better understanding of the location of portions of the first end cap  702 . A proximate portion  712  of the first end cap  702  is circular, having a diameter D 10 , and having a flat end surface  714 . A top surface  716  of the first end cap  702  runs perpendicular to the flat end surface  714 . 
   A distal portion  722  of the first end cap  702  is tube-like in shape, having the same diameter as the proximate portion  712 . The distal portion  722  of the first end cap  702  contains an end surface  732 , a plane of which is perpendicular to a plane of the top surface  716  of the first end cap  702 . The distal portion  722  also contains a bottom surface  734  that runs parallel to the top surface  716  and an internal surface  736  that runs parallel to the flat end surface  714  of the proximate portion  712 . The bottom surface  734  of the distal portion  722  defines an exterior portion of a cylindrical gap  740  located central to the distal portion  722  of the first end cap  702 . A diameter D 11  of the cylindrical gap  740  is smaller than the diameter D 10  of the proximate portion  712 . 
   The second end cap  750  ( FIG. 12A ) is similar in shape and size to the first end cap  702 , and therefore, additional description of the second end cap  750  is not provided herein. Instead, reference can be made to the description of the first end cap  702 , provided hereinabove, for an understanding of the second end cap  750 . 
   It should be noted that while  FIG. 13  illustrates the proximate portion  712  of the first end cap  702  having a flat end surface  714 , and as mentioned above, the second end cap  750  is similar to the first end cap  702 , one having ordinary skill in the art would appreciate that the proximate portions of the end caps  702 ,  750  do not require presence of a flat end surface. Instead, the flat end surface may be convex or concave. In addition, instead of being circular, the first end cap  702  and the second end cap  750  may be square-like in shape, or they may be a different shape. Use of circular end caps  702 ,  750  is merely provided for exemplary purposes. The main function of the end caps  702 ,  750  is to provide a conductive connection that allows an electrical charge introduced to the first end cap  702  to traverse the conductive spheres  190  and be received by the second end cap  750 , therefore, many different shapes and sizes of end caps  702 ,  750  may be used as long as the conductive path is maintained. 
   Referring back to  FIG. 12A , it should be noted that in accordance with the fifth embodiment of the invention, a portion of the first end cap  702  and a portion of the second end cap  750  is located outside of the central member  140 , when the sensor  700  is assembled. 
     FIG. 14  is a cross-sectional side view of the omnidirectional tilt and vibration sensor  700  of  FIG. 12A , where the sensor  700  is in a closed state. 
     FIG. 15A  and  FIG. 15B  are cross-sectional side views of a tilt sensor  800 , in accordance with a sixth exemplary embodiment of the invention. As is show by  FIGS. 15A and 15B , the first and second end caps  810 ,  860  have a top lip portion that overlaps a portion of the central member  140 . The embodiment of the central member  140  illustrated by  FIG. 15A  and  FIG. 15B  is the central member  140  of  FIG. 3 . 
   The first end cap  810  contains a first top lip portion  820  that overlaps the top surface  142  of the central member  140 . The first top lip portion  820  of the first end cap  810  is shown to overlap the top surface  142  of the central member  140  more in the embodiment of  FIG. 15A  than in the embodiment of  FIG. 15B . The second end cap  860  contains a second top lip portion  840  that overlaps the top surface  142  of the central member  140 . The first top lip portion  820  and the second top lip portion  840  form a cavity in which the central member  140  fits when assembling the tilt sensor  800 . 
   It should be emphasized that the above-described embodiments of the present invention are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the invention. Many variations and modifications may be made to the above-described embodiments of the invention with departing substantially from the spirit and principles of the invention. All such modifications and variations are intended to be included herein within the scope of this disclosure and the present invention and protected by the following claims.