Patent Grant
8242867
The present invention relates to a magnetic switch. More particularly, the present invention relates to tamper-resistant balanced magnetic switch.
Security systems and/or security alarm systems often use magnetic switches attached to doors, windows, and other structures to detect the unauthorized opening and/or manipulation of the door, window, or other structures. However, previous magnetic switch designs have been prone to tampering and/or have exhibited unacceptable reliability.
For example, one type of magnetic switch is a reed switch. However, these switches may be defeated by clever application of, for example, one or more external magnets. Specifically, a compact high energy magnet may be positioned in proximity to the reed switch to operate (to either open or close depending on the control scheme) the reed switch illicitly and/or without authorization. Once they have defeated the reed switch, an intruder may open and/or manipulate the door, window, or other structures without triggering the security system and/or security alarm systems.
Presently known art attempts to address this problem, but have not completely solved the problem. For example a number of magnetic switches have been proposed in the past to overcome the inherent limitation and serious deficiencies of reed switches. The following represents at least a partial list of known related art:
The teachings of each of the above-listed citations (which does not itself incorporate essential material by reference) are herein incorporated by reference. None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as described and claimed.
U.S. Pat. No. 5,877,664 to Jackson, Jr. teaches a proximity switch system includes a switch portion, configured to connect and disconnect at least one electrical path, and a magnetically active actuator. The switch portion has a casing formed of a magnetically noninteracting material, at least one electrical contact disposed in the casing, a magnetically active armature member moveable along the casing between a first position and a second position, wherein the armature member contacts the electrical contact when in the first position to connect the at least one electrical path and the armature member being electrically isolated from the electric contact when in the second position to disconnect the at least one electrical path, and a magnetically active biasing member disposed in the casing, wherein the biasing member magnetically interacts with the armature member to bias the armature member in one of the first and second positions. The magnetically active actuator is movable with respect to the switch portion between proximal and distal positions. The actuator magnetically interacts with the armature member when in the proximal position to move the armature to the other one of the first and second positions, and at least one of the armature member and the biasing member include a magnet.
U.S. Pat. No. 5,929,731 to Jackson, Jr. teaches a balanced magnetically-actuated proximity switch assembly for use in a monitoring system that includes a switch assembly and an actuating assembly. The switch assembly has a plurality of magnetic switches with respective magnetic directionalities. The actuating assembly is movable relative to the switch assembly and has a plurality of magnets. Each one of the magnets produces a magnetic field corresponding to the magnetic directionality of a respective one of the magnetic switches.
U.S. Pat. No. 7,248,136 to Habboosh teaches a universal magnetic switching assembly for detecting relative movement between first and second members, the universal switching assembly including, a flux directing device for selectively directing a majority of applied magnetic flux, such that an externally applied magnetic field cannot be used to defeat the magnetic switch assembly. The magnetic switching assembly also including at least one tamper switch to detect application of an external magnetic field.
The magnetic switch assembly of an embodiment of the present invention presents numerous advantages, including: (1) increased resistance to tampering by the introduction of one or more external magnets; (2) increased resistance to tampering by prying off and/or otherwise interfering with one or more portions of the magnetic switch assembly; (3) increased reliability by reducing contamination of internal components; (4) decreased contamination of internal components by the use of electronics-grade potting and/or encapsulation material; (5) increased reliability by utilizing passive circuit components; (6) increased electrical coupling of one or more magnets to one or more circuits by including a conductive coating on the magnets; and (7) increased electrical coupling of one or more magnets to one or more circuits by including self-cleaning rotation of the magnets.
Additional advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. Further benefits and advantages of the embodiments of the invention will become apparent from consideration of the following detailed description given with reference to the accompanying drawings, which specify and show preferred embodiments of the present invention.
The accompanying drawings, which are incorporated into and constitute a part of this specification, illustrate one or more embodiments of the present invention and, together with the detailed description, serve to explain the principles and implementations of the invention.
Turning now descriptively to the drawings, in which similar reference characters denote similar elements throughout the several views, the figures illustrate the magnetic switch assembly of an embodiment of the present invention. With regard to the reference numerals used, the following numbering is used throughout the various drawing figures:
Before beginning a detailed description of the subject invention, mention of the following is in order. When appropriate, like reference materials and characters are used to designate identical, corresponding, or similar components in differing figure drawings. The figure drawings associated with this disclosure typically are not drawn with dimensional accuracy to scale, i.e., such drawings have been drafted with a focus on clarity of viewing and understanding rather than dimensional accuracy.
In the interest of clarity, not all of the routine features of the implementations described herein are shown and described. It will, of course, be appreciated that in the development of any such actual implementation, numerous implementation-specific decisions must be made in order to achieve the developer's specific goals, such as compliance with application- and business-related constraints, and that these specific goals will vary from one implementation to another and from one developer to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of engineering for those of ordinary skill in the art having the benefit of this disclosure.
As shown in
The switch base 20 may further include a plurality of magnets. In an embodiment, the magnets are substantially cylinder shaped neodymium iron boron permanent magnets. More specifically, the switch base 20 may include four lateral switch base magnets 22 arranged in two pairs. Each pair of lateral switch base magnets 22 may be located approximately between the center of the tamper insert 26 and each lateral end of the tamper insert 26. Further, each pair of lateral switch base magnets 22 may define an oblique line relative to the edge of the switch base 20 that may mount to the door frame or the like. In an embodiment, each pair of lateral switch base magnets 22 may define an approximately forty-five degree angle relative to the edge of the switch base 20 that may mount to the door frame or the like. The lateral switch base magnets 22 may be substantially fixed within and/or secured by the switch base 20.
As noted, the tamper insert protrusion 27 may protrude into the switch base 20 when the switch base 20 is coupled to the tamper insert 26. In an embodiment, the tamper insert protrusion 27 may include a center switch base magnet 24. The switch base 20 may include a second center switch base magnet 24 adjacent to the tamper insert protrusion 27. The pair of center switch base magnets 24 may define a line that is substantially parallel to the edge of the switch base 20 that may mount to the door frame or the like. Further, the pair of center switch base magnets 24 may be located substantially at the center of the switch base 20. The center switch base magnets 24 may be substantially fixed within and/or secured by the switch base 20 and the tamper insert protrusion 27 respectively.
The tamper insert 26 of an embodiment may include portions that are designed to fail upon tampering with the switch base 20 and/or switch housing 30 coupled thereto. For example, adjacent to the holes or aperture through which the tamper insert 26 may be attached with screws or other attaching means to a door frame, the tamper insert 26 may include a thinner portion of tamper insert 26 material, one or more scores, one or more perforations, or any other feature designed to fail upon tampering. More specifically, should someone attempt to pry the switch base 20 and/or the switch housing 30 coupled thereto off of, for example, a door frame the tamper insert 26 will shear, break, or otherwise fail so that at least the portion of the tamper insert 26 including tamper insert protrusion 27 will remain substantially affixed to the door frame or the like. Accordingly, as the switch base 20 and/or the switch housing 30 are pried while the tamper insert protrusion remains coupled to the door frame, the pair of center switch base magnets 24 will no longer define a line that is substantially parallel to the edge of the switch base 20 that may mount to the door frame or the like.
The interaction between the lateral armature magnets 36 and the center armature magnet 38 with the lateral switch base magnets 22, the center switch base magnets 24, and the actuating magnets 42 may open and/or close a circuit and/or otherwise generate a signal that may be communicated by the interface cable 50 to, for example, a security system (not illustrated) to detect whether the door is open or closed. The configuration of the magnets within the switch base 20, the switch housing 30, and the actuating magnet base 40, may further impede and/or substantially prevent magnetic switch assembly 10 tampering by the introduction of one or more magnets external to the magnetic switch assembly 10.
More specifically,
Further, the center armature magnet 38 may interact with the center switch base magnets 24. In doing so, the longitudinal axes of the substantially cylinder shaped center armature magnet 38 may substantially align with the parallel line defined by the pair of center switch base magnets 24. Further, the center armature magnet 38 may be generally attracted to the center switch base magnet 24 and may accordingly couple to the tamper circuit 28. The position and orientation of the lateral armature magnets 36 and the center armature magnet 38, and corresponding contact with one or more circuit elements and/or traces of tamper circuit 28, may open and/or close a circuit of tamper circuit 28 and/or otherwise generate a signal that may be detected by and/or communicated to, for example, a security system (not illustrated) via interface cable 50.
When the actuating magnet base 40 including actuating magnets 42 is within a particular actuation distance from and/or is substantially adjacent to the switch housing 30, the magnet switch assembly 10 will be in and/or convert to an actuated configuration. In an actuated configuration, the lateral armature magnets 36 interact with both the lateral switch base magnets 22 and the actuating magnets 42. As the actuating magnets 42 are stronger than the lateral switch base magnets 22, the lateral armature magnets 36 are attracted to the actuating magnets 42 more than they are attracted to the lateral switch base magnets 22. As a result, the lateral armature magnets both couple to the switch circuit 32 and rotate to substantially align with the poles of the actuating magnets 42. In an embodiment, when actuated, the lateral armature magnets 36 longitudinal axes may be substantially parallel to the edge of the switch base 20 that may mount to the door frame or the like.
Conversely, when actuated, the center armature magnet 38 may continue to interact with the center switch base magnets 24. In doing so, the longitudinal axes of the substantially cylinder shaped center armature magnet 38 may remain substantially aligned with the parallel line defined by the pair of center switch base magnets 24. Further, the center armature magnet 38 may remain generally attracted to the center switch base magnet 24 and may accordingly couple to the tamper circuit 28. While the magnetic switch assembly 10 is configured in the actuated configuration, the center armature magnet 38 may not couple to the switch circuit 32.
The position and orientation of the lateral armature magnets 36 and the center armature magnet 38, and corresponding contact with one or more circuit elements and/or traces of tamper circuit 28 and/or switch circuit 32 may further contribute to the tamper resistance of the magnetic switch assembly 10. For example, the particular positions and/or orientations of the lateral armature magnets 36 and the center armature magnet 38 in the non-actuated configuration compared to the actuated configuration may open and/or close one or more circuits of tamper circuit 28 and/or the switch circuit 32 and/or otherwise generate a signal indicative of the magnetic switch assembly 10 non-actuated or actuated configuration that may be detected by and/or communicated to, for example, a security system (not illustrated) via interface cable 50. The complexity of the magnetic interactions generated the non-actuated and actuated configurations of magnetic switch assembly 10 may increase the difficulty with which the magnetic interactions may be reproduced, for example by an external magnet or magnet assembly applied to the switch base 20 and/or the switch housing 30. More specifically, the complexity of the magnetic interactions generated by the non-actuated and actuated configurations of magnetic switch assembly 10 may increase the difficulty with the presence and/or proximity of the actuating magnet base 40 including actuating magnets 42 may be imitated and/or spoofed.
Further, as introduced, should someone attempt to pry the switch base 20 and/or the switch housing 30 coupled thereto off of, for example, a door frame the tamper insert 26 will shear, break, or otherwise fail so that at least the portion of the tamper insert 26 including tamper insert protrusion 27 will remain substantially affixed to the door frame or the like. Accordingly, as the switch base 20 and/or the switch housing 30 are pried while at least the tamper insert 26 portion including the tamper insert protrusion 27 remains coupled to the door frame, the pair of center switch base magnets 24 will no longer define a line that is substantially parallel to the edge of the switch base 20 that may mount to the door frame or the like. Accordingly, the center aperture magnet 38 may alter position and/or orientation, for example by rotating to remain aligned with the center switch base magnet 24 included in the switch base 20 and the center switch base magnet 24 that is included instead in the tamper insert protrusion 27. The alteration of the position and/or orientation of the center aperture magnet 38 may open and/or close one or more circuits of tamper circuit 28 or otherwise generate a signal indicative of the magnetic switch assembly 10 tampering that may be detected by and/or communicated to, for example, a security system (not illustrated) via interface cable 50.
The alteration of the position and/or orientation of the lateral aperture magnets 36 and center aperture magnet 38 to open and/or close one or more circuits of tamper circuit 28 and/or switch circuit 32 that may be detected by and/or communicated to, for example, a security system (not illustrated) via interface cable 50. To improve the electrical coupling, at least the lateral aperture magnets 36 and center aperture magnet 38 may include at least a conductive surface. For example, in an embodiment, the magnet lateral aperture magnets 36 and center aperture magnet 38 conducting surfaces may include gold conducting surfaces. Other materials in addition to and/or in lieu of gold may be coupled and/or applied to the conducting surfaces to increase the electrical coupling between the lateral aperture magnets 36 and center aperture magnet 38 with traces and/or other circuit elements of tamper circuit 28 and/or switch circuit 32.
To further increase the electrical coupling and/or reliability of the electrical coupling between lateral aperture magnets 36 and center aperture magnet 38 with traces and/or other circuit elements of tamper circuit 28 and/or switch circuit 32, the switch circuit 32, armature block 34 (including the lateral armature magnets 36 and the center armature magnet 38) and tamper circuit 28 may be coupled to and/or substantially secured in the switch housing 30 with an electronics-grade potting and/or encapsulation material. The electronics-grade potting, and/or encapsulation material may not substantially leech, outgas, and/or otherwise expel contamination that may interfere with the electrical coupling between the lateral aperture magnets 36 and center aperture magnet 38 with traces and/or other circuit elements of tamper circuit 28 and/or switch circuit 32.
The rotation of at least the lateral armature magnets 36 between the non-actuated and actuated configuration of magnetic switch assembly 10 may further increase the electrical coupling and/or reliability of the electrical coupling between lateral aperture magnets 36 with traces and/or other circuit elements of tamper circuit 28 and/or switch circuit 32. For example, the rotation of the lateral aperture magnets 36 may scrub and/or otherwise clean the traces and/or other circuit elements of tamper circuit 28 and/or switch circuit 32. Specifically, the rotation of the lateral aperture magnets 36 may scrub and/or otherwise clean debris, oxidation, and/or contamination from the traces and/or other circuit elements of tamper circuit 28 and/or switch circuit 32.
Though described with reference to a door and a door frame, it is to be understood that the magnetic switch assembly 10 of an embodiment may be used for any application to detect between two configurations provided one configuration positions the actuating magnet base 40 adjacent to the switch base 20 and the switch housing 30 and the other configuration positions the actuating magnet base 40 away from the switch base 20 and the switch housing 30.
In operation, the magnetic switch assembly 10 of an embodiment may be altered and/or actuated between a non-actuated and an actuated configuration by the introduction of the actuating magnet base 40 including actuating magnets 42 in proximity and/or adjacent to the switch base 20 and the switch housing 30. The actuation of switch assembly 10 includes attracting the lateral armature magnets 36 to the actuating magnets 42. In an embodiment, attracting the lateral armature magnets 36 to the actuating magnets 42 further includes rotating the lateral armature magnets 36. The attraction and rotation of the lateral armature magnets 36 may electrically couple the lateral armature magnets 36 to the switch circuit 32 and/or alter the switch circuit 32 response. The lateral armature magnets 36 may substantially simultaneously electrically decouple from the tamper circuit 28.
The non-actuation of switch assembly 10 includes removing the actuating magnet base 40 including the actuating magnets 42 so that the lateral switch base magnets 22 attract the lateral armature magnets 36. In an embodiment, attracting the lateral armature magnets 36 to the lateral switch base magnets 22 further includes rotating the lateral armature magnets 36. The attraction and rotation of the lateral armature magnets 36 may electrically couple the lateral armature magnets 36 to the tamper circuit 28 and/or alter the tamper circuit 28 response. The lateral armature magnets 36 may substantially simultaneously electrically decouple from the switch circuit 32.
During normal operation of the magnetic switch assembly 10 between actuated and non-actuated configurations, the center armature magnet 38 remains attracted by and oriented to the center switch base magnets 24. Accordingly, the center armature magnet further 38 remains electrically coupled to the tamper circuit 28. Upon tampering, for example by the introduction of one or more external magnets and/or prying the switch base 20 and the switch housing 30 from the door frame, the center armature magnet 38 may rotate and/or alter its position and/or orientation. Accordingly, upon tampering, the center armature magnet 38 may electrically decouple from the tamper circuit 28 and/or alter the tamper circuit 28 response.
For each of the above configurations, the tamper circuit 28, the switch circuit 32, and/or the responses thereof may be detected by, for example, a security system (not illustrated) coupled to the magnetic switch assembly 10 via interface cable 50. The security system may detect between the non-actuated and actuated configurations of the magnetic switch assembly 10 as well as the presence of tampering of the magnetic switch assembly 10. More specifically the interaction of the center armature magnet 38 with the center switch base magnets 22 may be detected by the tamper circuit 28 as described above. The interaction of the lateral armature magnets 36 with the lateral switch base magnets 22 and/or actuating magnets 42 may be detected by the tamper circuit 28, the switch circuit 32, and/or a combination thereof.
Those skilled in the art will recognize that numerous modifications and changes may be made to the preferred embodiment without departing from the scope of the claimed invention. It will, of course, be understood that modifications of the invention, in its various aspects, will be apparent to those skilled in the art, some being apparent only after study, others being matters of routine mechanical, chemical and electronic design. No single feature, function or property of the preferred embodiment is essential. Other embodiments are possible, their specific designs depending upon the particular application. As such, the scope of the invention should not be limited by the particular embodiments herein described but should be defined only by the appended claims and equivalents thereof.
This application claims priority to U.S. Provisional Patent Application Ser. No. 61/165,462 filed Mar. 31, 2009, which is incorporated herein by reference.
| Number | Name | Date | Kind |
|---|---|---|---|
| 2520935 | Hubbell | Sep 1950 | A |
| 2573920 | McLeod | Nov 1951 | A |
| 2877361 | LeLand | Mar 1959 | A |
| 3273091 | Wales, Jr | Sep 1966 | A |
| 3535664 | Staar | Oct 1970 | A |
| 4210889 | Holce | Jul 1980 | A |
| 5239202 | Hostetler | Aug 1993 | A |
| 5668533 | Jackson et al. | Sep 1997 | A |
| 5694039 | Alfors | Dec 1997 | A |
| 5698909 | Miyazawa | Dec 1997 | A |
| 5877664 | Jackson, Jr. | Mar 1999 | A |
| 5929731 | Jackson, Jr. | Jul 1999 | A |
| 6246307 | Friedman | Jun 2001 | B1 |
| 7187259 | Habboosh | Mar 2007 | B1 |
| 7248136 | Habboosh | Jul 2007 | B2 |
| 20050110600 | Woods | May 2005 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20100245004 A1 | Sep 2010 | US |
| Number | Date | Country | |
|---|---|---|---|
| 61165462 | Mar 2009 | US |
