Abstract:
Small, low-profile magnetic switch assemblies ( 26, 76, 126, 168 ) include a base ( 38, 78, 156 ) equipped with first and second laterally spaced apart switch electrodes, indentations ( 62, 102, 158 ) between the electrodes, and electrically conductive movable components ( 72, 110, 166 ), which are magnetically shiftable between a first switch position in simultaneous contact with the base electrodes, and a second switch position out of such simultaneous contact. The switch position of the component ( 72, 110, 166 ) is determined by the magnetic field conditions experienced by the component ( 72, 110, 166 ). The indentations ( 62, 102, 158 ) and associated shiftable components ( 72, 110, 166 ) permit the assemblies ( 26, 76, 126, 168 ) to be constructed as comparatively tiny units, which may be mounted on circuit boards.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention is broadly concerned with very small and compact magnetic switch assemblies, which can be mounted on conventional circuit boards. More particularly, the invention is concerned with such switch assemblies having low-profile switch housings with internal electrodes and shiftable components within the housings that are shiftable between separate switch-operating positions depending upon the magnetic field conditions imposed upon the components. The switch assemblies may be used, e.g., as a part of window or door monitoring/alarm systems, or as proximity sensors. 
     Description of the Prior Art 
     Prior art alarm systems use magnetic switches attached to doors and/or windows for detecting unauthorized opening thereof. One common type of magnetic switch is a so-called reed switch. This type of switch is subject to unauthorized manipulation through use of an external magnet. That is, an intruder can use a strong magnet held in proximity to the reed switch to hold the switch closed (or open depending upon the control scheme), and thereby open a supposedly protected door or window without triggering the alarm system. 
     Magnasphere Corporation of Waukesha, Wis. commercializes a specialized type of magnetic switch giving improved performance and protection against external magnet manipulation. Such switches generally comprise a metallic housing with an internal switch ball shiftable between a first position in contact with a pair of switch electrodes and a second position out of such simultaneous contact. Switches of this type are disclosed in U.S. Pat. Nos. 5,977,873 and 7,291,794. Other prior references include U.S. Pat. Nos. 5,332,992, 5,530,428, 5,673,021, 5,880,659, 6,087,936, 6,506,987, 6,603,378, 6,803,845, 7,023,308, RE39,731, 7,825,801, 7,944,334, 8,228,191, 8,314,698, 8,487,726, 8,648,720, and 8,941,397, and EP 2638555. 
     Although the present-day Magnasphere switches are of inherently small and compact design, they are generally too large for direct mounting on circuit boards. It would be a decided advantage if even more compact switch assemblies could be provided, which retain the unique operating properties of the existing switches, while also being mountable directly on circuit boards. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the problems outlined above and provides very compact and small magnetic switch assemblies, which can be installed in conventional circuit boards. The switch assemblies may also be mounted and soldered directly to circuit boards using automatic welding equipment. The switches may be used as a part of a monitoring/alarm system to detect unauthorized opening of an openable structure such as a door or window. In such contexts, the switches of the invention include a base presenting a lower surface and an opposed upper surface, the base having first and second laterally spaced apart electrodes with an indentation between the electrodes and extending below the upper surface of the base. A cover is secured to the base and extends upwardly therefrom, the base and cover cooperatively presenting a housing. A magnetic operating assembly also forms a part of the switch assembly, and includes an electrically conductive component within the housing and shiftable between a first switch position, wherein the component is in simultaneous electrical contact with the first and second electrodes, and a second shift position, where the component is out of such simultaneous contact. The operating assembly serves to create a magnetic field condition to shift the component to the first switch position when the switch is at one location, and to create a different magnetic field condition to shift the component to the second switch position when the switch is at another location. 
     The switch operating assembly preferably comprises a biasing element carried by the housing, and a separate actuating component. The switch is shiftable between a position where the housing is adjacent the actuating component, and a position where the housing is remote from the actuating component. 
     The switches hereof may also be used in other contexts, such as proximity sensors. For example, a magnetic switch assembly suitable for this intended use comprises a base and a cover secured to the base, the base and cover cooperatively defining a housing. The base has a bottom surface and an opposed top surface, and further includes first and second spaced apart electrodes with an indentation between the electrodes and extending below the upper surface of the base. An electrically conductive component is located within the housing and is shiftable between first and second switch positions, depending upon the magnetic field conditions acting on the component, namely a first switch position when the component is in simultaneous contact with the first and second electrodes, the second switch position being when the component is out of such simultaneous contact. The switch remains in one of its switch positions until the switch comes into proximity with a metallic structure which magnetically couples with the shiftable component; at this point, the component shifts to the second switch position, thereby signaling the proximity of the metallic structure. 
     In preferred forms, the shiftable components of the switches are in the form of spherical balls, but this is not an essential feature of the invention. The shiftable components may be of any convenient shape or size consistent with the geometries of the switch housings. Moreover, the electrodes within the switch housings may be defined by different wall surfaces, such as inclined and/or upright surfaces, so long as appropriate indentations are provided to assure smooth operation of the switch assemblies. 
     The switch assemblies may be in the form of single-pole, single-throw (SPST) switches, or more complex switch assembly designs, such as single-pole, double-throw (SPDT) switches. In the latter case, the switch housings are provided with third and fourth laterally spaced apart electrodes located above the first and second electrodes, and the electrodes are appropriately configured for SPDT operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top perspective view of a magnetic switch in accordance with the invention; 
         FIG. 2  is a bottom perspective view of the magnetic switch illustrated in  FIG. 1 ; 
         FIG. 3  is a vertical sectional view of the magnetic switch illustrated in  FIG. 1 , shown in one of its switch-operating conditions; 
         FIG. 4  is a top perspective view similar to that of  FIG. 1 , but with portions of the switch housing removed to further illustrate the construction of the switch; 
         FIG. 5  is a top perspective view of another magnetic switch in accordance with the invention; 
         FIG. 6  is a bottom perspective view of the magnetic switch illustrated in  FIG. 5 ; 
         FIG. 7  is a vertical sectional view of the magnetic switch illustrated in  FIG. 5 ; 
         FIG. 8  is a top perspective view similar to that of  FIG. 5 , but with portions of the switch housing removed to further illustrate the construction of the switch; 
         FIG. 9  is a top perspective view of another magnetic switch in accordance with the invention; 
         FIG. 10  is a bottom perspective view of the magnetic switch illustrated in  FIG. 9 ; 
         FIG. 11  is a top perspective view similar to that of  FIG. 9 , but with portions of the switch housing removed to further illustrate the construction of the switch; 
         FIG. 12  is a vertical sectional view of the magnetic switch illustrated in  FIG. 9 ; 
         FIG. 13  is a top perspective view of another magnetic switch in accordance with the invention; 
         FIG. 14  is an exploded view of the switch depicted in  FIG. 13 , illustrating the switch parts; 
         FIG. 15  is a vertical sectional view of the switch illustrated in  FIG. 13 ; 
         FIG. 15A  is a vertical sectional view similar to that of  FIG. 15 , but illustrating a modified form of the switch of  FIG. 13 , including internal connectors in lieu of the projecting connection tongues illustrated in  FIGS. 13-15 ; 
         FIG. 16  is a top perspective view of another magnetic switch in accordance with the invention, in the form of a single-pull, double-throw switch; 
         FIG. 17  is an exploded view of the switch depicted in  FIG. 16 , illustrating the switch parts; 
         FIG. 18  is a vertical sectional view of the switch illustrated in  FIG. 16 ; 
         FIG. 18A  is a vertical sectional view similar to that of  FIG. 18 , but illustrating a modified form of the switch of  FIG. 16 , including internal connectors in lieu of the projecting connection tongues illustrated in  FIGS. 16-18 ; and 
         FIG. 19  is an elevational view of a conventional door protected using a magnetic switch in accordance with the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As indicated previously, the switch assemblies of the invention may be used in a variety of contexts. One preferred use thereof is illustrated in  FIG. 19 , wherein a switch assembly  20  includes a housing  22  adapted to be mounted within a stationary door frame  24  and having a magnetic switch  26  therein. In this illustration, the assembly  20  is designed to monitor the condition of door  27  mounted within frame  24  via hinges  30 . The switch  26  operates in conjunction with an actuating body  32  mounted on door  27 , so that when the latter is closed, the body  32  is in direct adjacency with the switch  26 . The switch  26  is normally located within and as a part of an otherwise conventional circuit board (not shown) having typical monitoring/alarm circuitry. A pair of electrical leads  34 ,  36  extend from the board and are operably coupled with an alarm or other perceptible door-monitoring device. 
     The magnetic switch  26  is illustrated in  FIGS. 1-4  and includes a base  38  and a mating cover  40  cooperatively presenting a housing  42  having an open space  44  above base  38 . The base  38  includes a substantially quadrate metallic outer body  46  presenting a vertical, circumscribing outer surface  48  and an inner surface having a vertical face  50 , an oblique inboard face  52 , a top surface  54 , and an opposed bottom surface  55 . The base  38  further has a central metallic body  56  presenting a pyramidal upper surface  58  and an opposed bottom surface  59 . A substantially quadrate dielectric ring  60  is interposed between central body  56  and outer body  46 , as best seen in  FIG. 4 , in order to electrically isolate the bodies  46 ,  56 . It will be observed that the oblique surface  52  and pyramidal surface  58  cooperatively define a continuous indentation  62 , which extends below the top surface  54  and the apex of surface  58 . The outer body  46  and central body  56  serve as first and second switch electrodes operably coupled with the leads  34 ,  36  (see  FIG. 2 ). 
     The cover  40  may be formed of metallic or synthetic resin material, and includes a quadrate sidewall  64 , a top wall  66 , and a continuous arcuate shoulder  68  between the walls  64 ,  66 . 
     The overall magnetic switch  26  also has a biasing disk  70  centrally located on top wall  66 , as well as a shiftable component preferably in the form of a spherical switch ball  72  located within space  44 . The ball  72  is magnetically shiftable between alternate first and second positions, i.e., a first position shown in bold line in  FIG. 4  in simultaneous contact with the oblique and pyramidal surfaces  52 ,  58 , and a second position illustrated in phantom out of such simultaneous contact. Of course, the disk  70  could also be mounted within the interior of the assembly, e.g., on the underside of top wall  66 . 
     The disk  70 , ball  72 , and actuating body  28  cooperatively provide a magnetic switching assembly broadly referred to by the numeral  74 , which serves to operate magnetic switch  26 . In preferred forms, the ball  72  is made of a suitable permanent magnetic material (or is coated with such a material), whereas disk  70  and body  28  are made of corresponding metallic materials, which magnetically couple with ball  72 , i.e., the materials are capable of attracting the ball  72 . 
     Again referring to  FIG. 19  where door  27  is in the closed position with body  32  adjacent housing  22 , the magnetic coupling and attraction between body  32  and ball  72  causes the latter to assume the first position, illustrated in  FIG. 4 , against the bias of disk  70 . However, when the door  27  is opened, thereby separating the body  28  and housing  22 , the biasing disk  70  comes into play in order to magnetically couple with and shift the ball  72  upwardly to the phantom line position of  FIG. 4 , wherein the ball  72  is out of the simultaneous electrode contact, and is in contact only with the cover  40 . It will be understood though, that the disk  70  and body  28  could be formed of magnetic material, whereas the ball  72  comprises metallic material. In this configuration, the switch  26  would operate in the same manner owing to the magnetic coupling and attraction between the ball  72 , disk  70 , and body  28 . Of course, combinations of these configurations are also possible. What is important is that the magnetic assembly  74  be designed so as to magnetically move the ball  72  between the first and second positions thereof as the result of changing the position of housing  22  relative to body  28 . 
       FIGS. 5-8  illustrate another magnetic switch  76  in accordance with the invention, which also generally includes a base  78  and mating cover  80  cooperatively defining a housing  82 , the latter having an open space  84 . The base  78  has an outermost annular metallic body  86  presenting an outer surface  88 , an opposed inner surface  89 , a top surface  90 , and an opposed bottom surface  92 . Additionally, the base includes a central body  94  having a cylindrical section  95 , a conical uppermost surface  96  and a bottom surface  98 . A dielectric ring  100  is located between the bodies  86  and  94 , with the latter being first and second electrodes. Note also that the ring  100  has a height less than that of the bodies  86 ,  94 , thereby creating a continuous, circular raceway indentation  102  between the inner surface  89  and section  95 . Furthermore, the junctures between the surfaces  89  and  90 , and between section  95  and surface  96 , create a pair of point contact surfaces  104 ,  106 . The cover  80  has a circular sidewall  81  affixed to body  86 , and a top  81   a.    
     The switch  76  also includes a magnetic operating assembly  108  including a shiftable switch element in the form of ball  110  and biasing disk  112  mounted on top  81   a . As illustrated in  FIG. 7 , the ball  110  is magnetically shiftable between first and second switch positions, as in the case of switch  26 . In this connection, note that in the first switch position the ball  110  makes essentially point contact with the surfaces  104 ,  106 , which assists in the prevention of locking or sticking of the ball in the first switch position. The switch  76  operates in exactly the same fashion as switch  26  when used in the context of an alarm switch or the like. 
       FIGS. 9-12  illustrate a still further embodiment of the invention in the form of a magnetic switch  114 . The switch  114  is closely analogous to switch  76 , and differs only in the shape of the central body/second electrode thereof. Accordingly, the same reference numerals applicable to switch  76  are used with respect to the switch  114 . However, in the switch  114 , the central body  116  of the base  78  is in the form of a cylindrical or rod-like element with planar top and bottom surfaces  118 ,  120  and a circular sidewall  122 . Thus, a continuous circular raceway indentation  124  is provided between the bodies  86  and  116 . 
       FIGS. 13-15  depict a magnetic switch  126  of somewhat different construction as compared with the earlier embodiments. The switch  126  has, from bottom to top, an electrically conductive bottom plate  128 , dielectric ring  130 , electrically conductive intermediate annular plate  132 , a pair of stacked dielectric rings  134 ,  136 , top plate  138 , and biasing disk  140 . 
     In detail, the bottom plate  128  has an essentially circular main body  142  with an outwardly projecting connector tongue  144  and a central, upwardly extending, substantially conical projection  146 . The rings  130  and  134 ,  136  are identical and are simply annular bodies of washer-like construction (if desired, the rings  134 ,  136 , could be replaced by a thicker unitary ring). The annular plate  132  includes an outermost flat peripheral segment  148  with an inwardly and downwardly extending oblique wall  150  terminating in a central opening  152 , and an electrical connection tongue  153 . The top plate  138  is of circular design and has a central, depending conical projection  154 , which is not essential to the operation of switch  126 . 
     As best illustrated in  FIG. 15 , the plate  128 , ring  130 , and plate  132  cooperatively define a base  156  for the switch  126 , with the wall  150  and projection  146  defining first and second laterally spaced apart electrodes, as well as an indentation  158  therebetween. In like manner, the rings  134  and  136 , together with top plate  138  cooperatively define a cover  160 , which, in combination with the base  156 , creates a housing  162  having an open space  164  therein. Additionally, the switch  126  has a shiftable component, again in the form of an electrically conductive ball  166 , which is magnetically moveable between the full and phantom line switch positions of  FIG. 15 , i.e., between a first switch position in simultaneous contact with projection  146  and wall  150 , and a second switch position out of such contact. The operation of switch  126  is again identical with that of the previously described switches, and is dependent upon the magnetic conditions imposed upon the ball  166 . 
       FIG. 15A  illustrates a switch  126   a , which is identical with switch  126  except for the use of internal connectors  153   a  and  144   a . As illustrated, the connector  153   a  includes a depending internal leg  153   b  with a short connector pad  153   c . The connector  144   a  has a connector pad  144   b  adjacent leg  153   b  and pad  153   c . In all other respects, the switch  126   a  is identical with switch  126 . 
       FIGS. 16-18  illustrate a single-pole, double-throw (SPDT) switch  168  in accordance with the invention. The switch  168  has many of the same components as switch  126 , and thus like parts have been numbered identically between these two embodiments. There are three principal differences between the switches  126  and  168 . In particular, the switch  168  is provided with an intermediate annular plate  170 , which is located between the dielectric rings  134  and  136 ; the top plate  138  is equipped with an electrical connection tongue  172 ; and the biasing element  174  is in the form of an annular body. The annular plate  170  is in many respects a mirror image of the plate  132 , having a circular peripheral segment  176 , an upwardly and inwardly extending wall  178  terminating in a central opening  180 , and an electrical connection tongue  182 . Thus, the wall  178  and the wall defining projection  154  serve as third and fourth electrodes, respectively. 
     Referring to  FIG. 18 , it will be seen that the plate  170  is in direct opposition to plate  132 , and that the plate  170  and top plate  138  cooperatively define an upper circular raceway indentation  184  as an essentially mirror image to lower indentation  158 . The indentation  184  is defined by the conical projection  154  and the wall  178 . The ball  166  is magnetically shiftable within the housing  162  between a first switch position shown in bold lines, where the ball  166  simultaneously contacts the first and second electrodes represented by the wall  150  and upwardly extending projection  146 , and a second switch position shown in phantom, where the ball simultaneously contacts the third and fourth electrodes represented by the wall  178  and projection wall  154 . Finally, the connection tongues  153  and  182  are interconnected by means of soldering or any other suitable means, thus defining the SPDT functionality of the switch  168 . The switch  168 , when used in the  FIG. 19  context, operates exactly as described above, i.e., the ball  166  is magnetically shifted depending upon the magnetic field conditions imposed upon it by body  28  or disk  174 , as the case may be. 
       FIG. 18A  illustrates a modified switch  168   a , which is identical with switch  168  save for the provision of internal connectors  144   c ,  172   a , and  182   a . As illustrated, the connector  172   a  has a depending internal leg  172   b  and a connection pad or foot  172   c . Likewise, the connector  182   a  has a depending internal wall  182   b  and a connection foot or bad  182   c . The connector  144   c  terminates inboard of the outer surface of the switch  168   a , as illustrated. 
     It will be appreciated that while the switches of the invention have been described in the context of a security system for doors, the invention is not so limited. That is, the switches may be used in security systems for windows or any other openable structures, e.g., windows. Moreover, the switches hereof may be used in any environment where a switch condition change is effected by an alteration in the magnetic field condition operating on the ball  72 ,  110 , or  166 , or other movable component. For example, the switches can be readily adapted for use as proximity sensors. In this environment, the switches would signal the presence of a body, which magnetically couples with the movable ball within the switch. Thus, the switches can be located at a selected sensing position and, in the event that a magnetic coupling structure comes into proximity with the switches, a magnetic attraction is effected between structure and the switch ball or other movable component, thereby signaling the presence of the coupling structure.