Abstract:
A tilt sensor contains a first electrically conductive element, a second electrically conductive element, an electrically insulative element, and either a plurality of electrically conductive weights, or a first electrically conductive weight and a non-conductive weight. The electrically insulative element is connected to the first electrically conductive element and the second electrically conductive element. In addition, the plurality of electrically conductive weights are located within a cavity of the tilt 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 APPLICATION 
   This application is a continuation-in-part, claiming priority to the copending U.S. patent application entitled, “TILT SENSOR AND METHOD OF PROVIDING THE SAME,” having Ser. No. 11/336,343, filed Jan. 20, 2006, which is incorporated herein by reference in its entirety. 

   FIELD OF THE INVENTION 
   The present invention is generally related to sensors, and more particularly is related to a tilt sensor. 
   BACKGROUND OF THE INVENTION 
   Many different electrical tilt 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 U.S. 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 state (ON). To change the tilt switch into an open state (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 to an open state (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 are generally constructed with a form factor that is difficult to attach to printed circuit boards using automated manufacturing equipment, and are costly to produce because of need to assemble numerous separate parts to form the switch. 
   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 a tilt sensor and a method of construction thereof. Briefly described, in architecture, one embodiment of the system, among others, can be implemented as follows. The tilt sensor contains a first electrically conductive element, a second electrically conductive element, an electrically insulative element, and a plurality of electrically conductive weights. The electrically insulative element is connected to the first electrically conductive element and the second electrically conductive element. In addition, the plurality of conductive weights are located within a cavity of the tilt 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. Alternatively, a first conductive weight may be conductive, while a second conductive weight is non-conductive. In addition, embodiments are provided utilizing only a single conductive weight. 
   The present invention can also be viewed as providing methods for assembling a tilt 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 broadly be summarized by the following steps: fitting a distal portion of the first electrically conductive element within a 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. 
   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 tilt 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. 3A  is a cross-sectional side view of the central member of  FIG. 1 , in accordance with the first exemplary embodiment of the invention. 
       FIG. 3B  is a cross-sectional side view of the central member of  FIG. 1 , in accordance with an alternative embodiment of the invention. 
       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 tilt sensor of  FIG. 1 . 
       FIG. 6A  and  FIG. 6B  are cross-sectional side views of the tilt sensor of  FIG. 1  in a closed state (ON), in accordance with the first exemplary embodiment of the invention. 
       FIG. 6C  is a cross-sectional side view of the tilt sensor having the central member of  FIG. 3B . 
       FIG. 6D  is a cross-sectional side view of the tilt sensor of  FIG. 1  having a single conductive sphere, in accordance with an alternative embodiment of the invention. 
       FIGS. 7A ,  7 B,  7 C, and  7 D are cross-sectional side views of the tilt sensor of  FIG. 1  in an open state (OFF), in accordance with the first exemplary embodiment of the invention. 
       FIG. 8  is a cross-sectional side view of a tilt sensor, in accordance with a third exemplary embodiment of the invention. 
       FIG. 9  is a cross-sectional side view of a tilt sensor, in accordance with a fourth exemplary embodiment of the invention. 
       FIG. 10  is a cross-sectional side view of a tilt sensor, in accordance with a fifth exemplary embodiment of the invention. 
       FIG. 11A  and  FIG. 11B  are cross-sectional side views of a tilt sensor, in accordance with a sixth exemplary embodiment of the invention. 
       FIGS. 12A and 12B  are cross-sectional side views of a tilt sensor, in accordance with a seventh exemplary embodiment of the invention. 
       FIG. 13A  illustrates the tilt sensor of  FIG. 12A  and  FIG. 12B  having a single conductive sphere, in accordance with an alternative embodiment of the invention, where the tilt sensor is in an open state (off). 
       FIG. 13B  illustrates the tilt sensor of  FIG. 12A  and  FIG. 12B  having a single conductive sphere, in accordance with an alternative embodiment of the invention, where the tilt sensor is in a closed state (on). 
       FIG. 14  is a cross-sectional side view of the first end cap of  FIG. 12A  and  FIG. 12B , which may be referred to for a better understanding of the location of portions of the first end cap. 
       FIGS. 15A ,  15 B, and  15 C are cross-sectional side views of a tilt sensor, in accordance with an eighth exemplary embodiment of the invention, where the tilt sensor contains one conductive sphere and one non-conductive sphere. 
       FIGS. 16A ,  16 B, and  16 C are cross-sectional side views of a tilt sensor, in accordance with a ninth exemplary embodiment of the invention, where the tilt sensor contains one conductive sphere and one non-conductive sphere. 
   

   DETAILED DESCRIPTION 
   The following describes a tilt sensor. The tilt 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 tilt sensor  100 , in accordance with a first exemplary embodiment of the invention. 
   Referring to  FIG. 1 , the tilt 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). Specifically, the first end cap  110  is conductive and 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 first end cap  110  has a proximate portion  112  and a distal portion  122 . 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. This disk shaped portion 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  FIG. 4  illustrates the proximate portion  162  ( FIG. 4 ) of the second end cap  160  as 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 a different 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 conductive connection that allows 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. A length L 1  of the cylindrical gap  128  extends from the inner surface  132  of the first end cap  110  to the outer surface  130  of the first end cap  110 . 
   It should be noted that the length L 1  of the cylindrical gap  128  may differ, as long as a central cavity ( 200 ) of the tilt sensor  100  is long enough to fit the conductive spheres  190  therein without having the conductive spheres  190  touching both the first end cap  110  and the second end cap  160  at the same time. 
   Referring to  FIG. 1  and  FIG. 3A , 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. 3A  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 rectangle. 
   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. 3A ). 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 tilt 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 . 
   A length L 2  of the hollow center  150  extends from the proximate surface  144  of the central member  140  to the distal surface  148  of the central member  140 . It should be noted that the length L 1  of the cylindrical gap  128  is smaller than the length L 2  of the hollow center  150 . 
     FIG. 3B  is a cross-sectional side view of the central member of  FIG. 3A , in accordance with an alternative embodiment of the invention, where the central member  600  contains a top surface  610  and an outer lip  620 . A top portion of the outer lip  620  is the top surface  610 . The outer lip  620  also contains an outer lip end surface  622  and an outer lip bottom surface  624 , where the outer lip bottom surface  624  is perpendicular to the outer lip end surface  622 . Of course, the outer lip bottom surface  624  is not required to be perpendicular to the outer lip end surface  622 . Similar to the central member of  FIG. 3A , the central member  600  of  FIG. 3B  contains a proximate surface  144 , a bottom surface  146 , a distal surface  148 , and a hollow center  150 . 
   The top surface  610  of the central member  600  has a length L 4 , while a length L 2  of the hollow center  150  extends from the proximate surface  144  of the central member  600  to the distal surface  148  of the central member  600 . The outer lip end surface  622  extends a distance ½ (L 4 −L 2 ) from either the proximate surface  144  or from the distal surface  148  of the central member  600 . The distance ½ (L 4 −L 2 ) is the same or larger than the width of the top surface  116  of the proximate portion  112  of the first end cap  110 , thereby having the first end cap  110  and the second end cap  160  within the central member  600 . 
   As in the central member  140  of  FIG. 3A , the bottom surface  146  of the central member  600  of  FIG. 3B  defines the hollow center  150  having the 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  600 . In addition, the distance between the bottom lip surface  624  of the central member  600  defines a diameter D 8 . 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 smaller than diameter D 8 . In addition, a diameter D 6  (i.e., a diameter of the proximate portion  162  of the second end cap  160 ) is preferably slightly smaller than diameter D 8 . Of course, different dimensions of the central member  600  and end caps  110 ,  160  may also be provided. In addition, when the tilt sensor  100  is assembled, the proximate surface  144  of the central member  600  rests against the internal surface  118  of the first end cap  110 , and the bottom lip surface  624  of the central member  600  rests against the top surface  116  of the proximate portion  112 . Further, when the tilt sensor  100  is assembled, the distal surface  148  of the central member  600  rests against an internal surface  168  of the second end cap  160 , and the bottom lip surface  624  of the central member  600  rests against the top surface  166  of the proximate portion  162 . 
   Referring to  FIG. 1  and  FIG. 4 , 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. This disk shaped portion 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 also disk-like in 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 an outer surface  176 . In addition, the distal portion  172  of the second end cap  160  has a length L 3 , where the length L 3  of the distal portion  172  is smaller than the length L 2  of the hollow center  150  of the central member  140 . In fact, as is shown hereinafter with regard to  FIGS. 2-4 , the length L 2  of the hollow center  150  is larger than the combination of the length L 3  of the distal portion  172  of the second end cap  160  combined with the length L 1  of the cylindrical gap  128  of the first end cap  110 . 
   It should be noted that, while the outer surface  176  of the distal portion  172  is shown as being flat, one having ordinary skills in the art would appreciate that the outer surface  176  need not be flat. 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 . 
   Within the distal portion  172  of the second end cap  160 , the outer surface  176  joins the top surface  174 . It should be noted that while  FIG. 4  shows the cross-section of the outer surface  176  as being squared to the top surface  174 , the outer surface  176  may instead be rounded or of a different shape. Referring to  FIG. 4 , the distal portion  172  of the second end cap  160  is shown to be an extension of the proximate portion  162  of the second end cap  160 . It should be noted that while  FIG. 4  illustrates the outer surface  176  as running parallel to the flat end surface  164 , the outer surface  176  may instead be concave, conical, or hemispherical. 
   It should be noted that dimensions of the second end cap  160  are preferably similar to the 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 tilt 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 , when the tilt sensor  100  is assembled, the pair of conductive spheres  190  (also referred to as conductive weights), 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 a space provided between the outer surface  130  of the first end cap  110  and the outer surface  176  of the second end cap  110 . 
   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 outer surface  176  of the second end cap  160  form a central cavity  200  of the tilt 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  FIG. 6A  and  FIG. 6B , and  FIGS. 7A-7E . 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 than 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  200  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  110 , 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 tilt 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 ). 
   When assembled, 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 outer surface  176  of the second end cap  160  form the central cavity  200  of the tilt sensor  100  where the pair of conductive spheres  190  are confined. 
   In accordance with an alternative embodiment of the invention, the tilt 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 seal, thereby preventing any contaminant from entering the central cavity  200 . 
   The sensor  100  has the capability of being in a closed state (ON) or an open state (OFF), depending on location of the conductive spheres  190  within the central cavity  200  of the tilt sensor  100 .  FIG. 6A  and  FIG. 6B  are cross-sectional views of the tilt sensor  100  of  FIG. 1  in a closed state (ON), in accordance with the first exemplary embodiment of the invention. In order for the tilt sensor  100  to be maintained in a closed state (ON), an electrical charge introduced to the first end cap  110  is required to traverse at least one conductive sphere  192 ,  194  and be received by the second end cap  160 . For this reason, it should be noted that in accordance with an alternative embodiment of the invention, the tilt sensor  100  may also only contain a single conductive sphere  190  ( FIG. 6D ). 
   Referring to  FIGS. 6A and 6B , the tilt sensor  100  is in a closed state (ON) because the second conductive sphere  194  is touching the bottom surface  126  of the first end cap  110  and the second conductive sphere  194  is touching the outer surface  176  of the second end cap  160 , thereby providing a conductive path from the first end cap  110 , through the second conductive sphere  194 , to the second end cap  160 . 
     FIG. 6C  is a cross-sectional side view of the tilt sensor  100  having the central member  610  of  FIG. 3B . As shown, the tilt sensor  100  of  FIG. 6C  is in a closed state (ON). 
   It should be noted that in accordance with the first exemplary embodiment of the invention, a distance between the first end cap  110  and the second end cap  160  (also referred to herein as a “gap”), when the tilt sensor  100  is assembled, is not so large as to allow the second conductive sphere  194  to fall therein. As a result of the gap not being too large, the tilt sensor  100  is very sensitive and allows for changing states from a closed state (ON) to an open state (OFF), or from an open state (OFF) to a closed state (ON), with slight tilting of the tilt sensor  100 . 
   In accordance with a second exemplary embodiment of the invention, the distance between the first end cap  110  and the second end cap  160  is large enough to allow the second conductive sphere  194  to rest within a gap created by the distance. It should be noted that, in accordance with the second exemplary embodiment of the invention, the gap is not large enough that the second conductive sphere  194  would be difficult to dislodge from the gap. Instead, the size of the gap dictates the angle of tilt required to allow the second conductive sphere  194  to move out of the gap, thereby making changing states of the tilt sensor  100  from a closed state (ON) to an open state (OFF) more difficult in the tilt sensor  100  of the second exemplary embodiment than in the tilt sensor  100  of the first exemplary embodiment of the invention. 
     FIGS. 7A-FIG .  7 D are cross-sectional views of the sensor  100  of  FIG. 1  in an open state (OFF), in accordance with the first exemplary embodiment of the invention. In order for the tilt sensor  100  to be maintained in an open state (OFF), an electrical charge introduced to the first end cap  110  cannot traverse the second conductive sphere  194  and be received by the second end cap  160 . Referring to  FIGS. 7A-7D , each of the tilt sensors  100  displayed are in an open state (OFF) because the second conductive sphere  194  is not in contact with the second end cap  160 . Of course, other arrangements of the first and second conductive spheres  192 ,  194  within the central cavity  200  of the tilt sensor  100  may be provided as long as no conductive path is provided from the first end cap  110  to the second conductive sphere  194 , to the second end cap  160 . 
     FIG. 8  is a cross-sectional side view of the present tilt sensor  300 , in accordance with a third exemplary embodiment of the invention. The tilt sensor  300  of the third exemplary embodiment of the invention does not contain a flange on the first end cap  110  or a flange on the second end cap  160 . 
     FIG. 9  is a cross-sectional side view of the present tilt sensor  400 , in accordance with a fourth exemplary embodiment of the invention. The tilt sensor  400  of the fourth exemplary embodiment of the invention does not contain a flange on the first end cap  110  or a flange on the second end cap  160 . In addition, the central member  140  extends over the proximate portion  112  and a distal portion  122  of the first end cap  110 , and over the proximate portion  162  and a distal portion  172  of the second end cap  160 . 
     FIG. 10  is a cross-sectional side view of the present tilt sensor  500 , in accordance with a fifth exemplary embodiment of the invention. The tilt sensor  500  of the fifth exemplary embodiment of the invention contains a first nub  502  located on the flat end surface  114  of the first end cap  110  and a second nub  504  located on a flat end surface  164  of the second end cap  160 . The nubs  502 ,  504  provide a conductive mechanism for allowing the tilt sensor  500  to connect to a printed circuit board (PCB) landing pad, where the PCB landing pad has an opening cut into it allowing the tilt sensor  500  to recess into the opening. Specifically, dimensions of the tilt sensor  500  may be selected so as to allow the tilt sensor  500  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  502 ,  504 , fitting the tilt sensor  500  into landing pad may press the first nub  502  against the first terminal and the second nub  504  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 tilt sensors described herein may have the same basic shape, thereby contributing to ease of preparing a printed circuit board (PCB) for receiving the tilt sensor. Specifically, a hole may be cut in a PCB the size of the tilt sensor (i.e., the size of the first and second end caps  110 ,  160  and the central member  140 ) so that the tilt sensor can drop into the hole, where the tilt sensor is prevented from falling through the hole when caught by the nubs  502 ,  504  that land on connection pads. In the exemplary embodiments of the invention where there are no nubs  502 ,  504 , the end caps 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. 11A  and  FIG. 11B  are cross-sectional side views of a tilt sensor  600 , in accordance with a sixth exemplary embodiment of the invention. As is show by  FIGS. 11A and 11B , the first and second end caps  610 ,  660  have a top lip portion that overlaps a portion of the central member  140 . The embodiment of the central member  140  illustrated by  FIG. 11A  and  FIG. 11B  is the central member  140  of  FIG. 3A . 
   The first end cap  610  contains a first top lip portion  620  that overlaps the top surface  142  of the central member  140 . The first top lip portion  620  of the first end cap  610  is shown to overlap the top surface  142  of the central member  140  more in the embodiment of  FIG. 11  B than in the embodiment of  FIG. 11A . The second end cap  630  contains a second top lip portion  640  that overlaps the top surface  142  of the central member  140 . The first top lip portion  620  and the second top lip portion  640  form a cavity in which the central member  140  fits when assembling the tilt sensor  600 . 
     FIGS. 12A and 12B  are cross-sectional side views of the present tilt sensor  700 , in accordance with a seventh exemplary embodiment of the invention. Specifically,  FIG. 12A  illustrates the tilt sensor  700  being in an open state (off), while  FIG. 12B  illustrates the tilt sensor  700  being in a closed state (on). 
   As is shown by  FIG. 12A  and  FIG. 12B , the first and second end caps  710 ,  760  have a top lip portion that overlaps a portion of the central member  740 . The embodiment of the central member  740  illustrated by  FIG. 12A  and  FIG. 12B  is the central member  140  of  FIG. 3A . In addition, the embodiment of the second end cap  760  illustrated by  FIG. 12A  and  FIG. 12B  is the second end cap  160  of  FIG. 4 . The first end cap  710  is further illustrated and described with reference to  FIG. 14 , as provided hereinbelow. 
     FIG. 14  is a cross-sectional side view of the first end cap  710 , which may be referred to for a better understanding of the location of portions of the first end cap  710 . The first end cap  710  has a proximate portion  712  and a distal portion  722 . The proximate portion  712  of the first end cap  710  is circular, having a diameter B 1 , and having a flat end surface  714 . A top surface  716  of the proximate portion  712  runs perpendicular to the flat end surface  714 . A width of the top surface  716  is the same width as a width of the entire proximate portion  712  of the first end cap  710 . The proximate portion  712  also contains an internal surface  718  located on a side of the proximate portion  712  that is opposite to the flat end surface  714 , where the top surface  716  runs perpendicular to the internal surface  718 . Therefore, the proximate portion  712  is in the shape of a disk. This disk shaped portion of the first end cap  710  is also referred to herein as a flange of the first end cap  710 . 
   It should be noted that while  FIG. 14  illustrates the proximate portion  712  of the first end cap  710  having a flat end surface  714 , and  FIG. 4  illustrates the proximate portion  162  ( FIG. 4 ) of the second end cap  160  as having a flat surface  164  ( FIG. 4 ), one having ordinary skill in the art would appreciate that the proximate portions  712 ,  162  ( FIG. 4 ) do not require presence of a flat end surface. Instead, the flat end surfaces  714 ,  164  ( FIG. 4 ) may be convex or concave. In addition, instead of being circular, the first end cap  710  and the second end cap  760  may be square-like in shape, or they may be a different shape. Use of circular end caps  710 ,  760  is merely provided for exemplary purposes. The main function of the end caps  710 ,  760  is to provide a conductive connection that allows an electrical charge introduced to the first end cap  710  to traverse conductive spheres  790  and be received by the second end cap  760 , therefore, many different shapes and sizes of end caps  710 ,  760  may be used as long as the conductive path is maintained. 
   The relationship between the top surface  716 , the flat end surface  714 , and the internal surface  718  described herein is provided for exemplary purposes. Alternatively, the flat end surface  714  and the internal surface  718  may have rounded or otherwise contoured ends resulting in the top surface  716  of the proximate portion  712  being a natural rounded progression of the end surface  714  and the internal surface  718 . 
   The distal portion  722  of the first end cap  710  is tube-like in shape, having a diameter B 2  that is smaller than the diameter B 1  of the proximate portion  712 . The distal portion  722  of the first end cap  710  contains a top surface  724  and a bottom surface  726 . The bottom surface  726  of the distal portion  722  defines an exterior portion of a cylindrical gap  728  located central to the distal portion  722  of the first end cap  710 . A maximum diameter B 3  of the cylindrical gap  728  is smaller than the diameter B 2  of the distal portion  722 . 
   As is also shown by  FIG. 14 , the distal portion  722  of the first end cap  710  also contains an inner surface  732 , the diameter B 4  of which is smaller than the maximum diameter B 3  of the cylindrical gap  728 . Specifically, the distal portion  722  of the first end cap  710  is conical in shape, but with a flat inner surface  732 . As a result, the bottom surface  726  of the first end cap  710  and the top surface  724  of the first end cap  710  are not parallel. In accordance with an alternative embodiment of the invention, the distal portion  722  of the first end cap  710  is still conical in shape, however, the flat inner surface  732  may be replaced by a differently shaped surface, such as, but not limited to, a hemispherical shape, or any other shape that does not result in a conductive sphere  792 ,  794  becoming fixed within the first end cap  710 . 
   The distal portion  722  of the first end cap  710  also contains an outer surface  730  that joins the top surface  724  and the bottom surface  726 . A distance between the top surface  724  of the first end cap  710  and the bottom surface  726  of the first end cap  710  increases as you travel from the outer surface  730  of the first end cap  710  toward the inner surface  732  of the first end cap  710 . 
   While  FIG. 14  illustrates the inner surface  732  as running parallel to the flat end surface  714 , as is noted hereafter, the inner surface  732  may instead be concave, conical, or hemispherical (such as that shown by  FIG. 16 ). A length P 1  of the cylindrical gap  728  extends from the inner surface  732  of the first end cap  710  to the outer surface  730  of the first end cap  710 . 
   Progression from the proximate portion  712  of the first end cap  710  to the distal portion  722  of the first end cap  710  is defined by a step where a top portion of the step is defined by the top surface  716  of the proximate portion  712 , a middle portion of the step is defined by the internal surface  718  of the proximate portion  712 , and a bottom portion of the step is defined by the top surface  724  of the distal portion  722 . 
   It should be noted that the length P 1  of the cylindrical gap  728  may differ, as long as a central cavity of the tilt sensor  700  is long enough to fit the conductive spheres  190  therein without having the conductive spheres  190  touching both the first end cap  710  and the second end cap  760  at the same time. 
   In accordance with an alternative embodiment of the invention, the tilt sensor  700  may also only contain a single conductive sphere  190 .  FIG. 13A  illustrates the tilt sensor of  FIG. 12A  and  FIG. 12B  having a single conductive sphere  190 , where the tilt sensor  700  is in an open state (off). Alternatively,  FIG. 13B  illustrates an embodiment of the invention where the tilt sensor  700  has a single conductive sphere  190 , and where the tilt sensor  700  is in a closed state (on). While the abovementioned embodiments contain two conductive spheres, it should be noted that an alternative embodiment of the invention may contain one conductive sphere and one nonconductive sphere.  FIGS. 15A ,  15 B, and  15 C are cross-sectional side views of the present tilt sensor  800 , in accordance with an eighth exemplary embodiment of the invention, where the tilt sensor  800  contains one conductive sphere  802  and one non-conductive sphere  804 . 
   As is shown by  FIG. 15A ,  FIG. 15B , and  FIG. 15C , a first end cap  810  and a second end cap  860  have a top lip portion that overlaps a portion of a central member  840 . The embodiment of the central member  840  illustrated by  FIG. 15A ,  FIG. 15B , and  FIG. 15C  is the central member  140  of  FIG. 3A . In addition, the embodiment of the second end cap  860  illustrated by  FIG. 15A ,  FIG. 15B , and  FIG. 15C  is the first end cap  710  of  FIG. 14 . Further, the embodiment of the first end cap  810  illustrated by  FIG. 15A ,  FIG. 15B , and  FIG. 15C  is the first end cap  110  of  FIG. 2 , but where the length L 1  of the cylindrical gap is smaller in  FIG. 15A ,  FIG. 15B , and  FIG. 15C  than it was in  FIG. 2 . 
   The tilt sensor  800  of  FIG. 15A ,  FIG. 15B , and  FIG. 15C  is typically open (e.g.,  FIG. 15A  and  FIG. 15B ) except when the conductive sphere  802  is in contact with both the first end cap  810  and the second end cap  860  (e.g.,  FIG. 15C ). 
   In accordance with a ninth exemplary embodiment of the invention,  FIG. 16A ,  FIG. 16B , and  FIG. 16C  also illustrate a tilt sensor  900  that has a conductive sphere  902  and a non-conductive sphere  904 . As is shown by  FIG. 16A ,  FIG. 16B , and  FIG. 16C , a first end cap  910  and a second end cap  960  have a top lip portion that overlaps a portion of a central member  940 . The embodiment of the central member  940  illustrated by  FIG. 16A ,  FIG. 16B , and  FIG. 16C  is the central member  140  of  FIG. 3A . In addition, the embodiment of the first end cap  910  illustrated by  FIG. 16A ,  FIG. 16B , and  FIG. 16C  is the first end cap  110  of  FIG. 2 . 
   The second end cap  960  of  FIG. 16A ,  FIG. 16B , and  FIG. 16C  is similar to the second end cap  860  of  FIG. 15A ,  FIG. 15B , and  FIG. 15C , except that an inner surface  932  of the second end cap  960  is hemispherical. The tilt sensor  900  of  FIG. 16A ,  FIG. 16B , and  FIG. 16C  is typically open (e.g.,  FIG. 16A  and  FIG. 16B ) except when the conductive sphere  902  is in contact with both the first end cap  910  and the second end cap  960  (e.g.,  FIG. 16C ). 
   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 without 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.