AU2010100689A4 - A module for use in door position monitoring systems - Google Patents

Description

1 Regulation 3.2A AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION (Innovation Patent) Name of Applicant/Nominated Person: Trevor David Leisk Address for Service: Davies Collison Cave, Patent Attorneys 1 Nicholson Street, MELBOURNE, Victoria, 3000. Invention title: "A module for use in door position monitoring systems" The following statement is a full description of this invention, including the best method of performing it known to me: 2 Technical field. This invention concerns the monitoring of the position of a door or other element that can be opened and closed. The "element" in the phrase "other element that can be opened and closed" includes a window, an access panel (such as an access 5 panel to a roof space, or to a switchboard or the like), a trapdoor, or a file-containing compactus that has to be moved to open its shelves to provide access thereto. This list of examples is not exhaustive. More particularly, the present invention concerns a module that contains a Magnasphere magnetic switch ("Magnasphere" is a trade mark), for use in an 10 electronic system that indicates when a closed "element" has been opened. Preliminary note. In this specification, including the claims, "directional" terms (such as "top", "bottom", "side", "upper", "lower", and the like) will be used in the sense that these terms would have with reference to a module of the present invention as 15 shown in Figures 1, 2 and 3 of the accompanying drawings. Background to the invention. When a room - a "secure room" - contains top secret documents or equipment, it is important that unauthorised entry into that room is prevented. In an establishment having multiple secure rooms, in which both authorised and unauthorised personnel 20 are present, it is very desirable to monitor who enters the secure rooms. Often it is impractical to post a guard on the door of every secure room. Visual surveillance using TV cameras is not always effective, particularly when the establishment has many secure rooms that need to be monitored. In this situation, it has become normal practice to monitor each door into a secure room using an electronic 3 system that is responsive to movement of the door, and that generates a signal that alerts surveillance operatives (and/or provides an alarm signal) whenever a door into a secure room is opened. Disclosure of the invention. 5 It is an objective of the present invention to provide a module that is economical to construct, easy to install, and effective to provide a signal whenever a closed door (or a closed "element", as described above) is opened. This objective is achieved using a device which includes a Magnasphere magnetic switch (usually called a Magnasphere switch). 0 A Magnasphere switch is a small magnetic switch, developed relatively recently by Magnasphere Corp. It is a significant improvement over conventional balanced reed switches. The Magnasphere magnetic switch has an electrode mounted above a cup-shaped housing of a non-magnetic metal. A magnetic sphere, constructed of an electrically conducting material, is positioned in the housing. When the magnetic 5 sphere is at the base of the housing, it contacts both the electrode and the housing, to close the switch. A ferromagnetic bias at the top of the housing will normally keep the magnetic sphere away from the base of the housing until a magnetic field or another ferromagnetic bias, applied externally of the Magnasphere switch, below the housing, over-rides the internal ferromagnetic bias and the magnetic sphere is 0 brought to the base of the housing to close the switch. Removal of the applied external magnetic field or ferromagnetic bias will mean that the magnetic sphere is once again under the influence of the internal ferromagnetic bias and will move away from the electrode, thus opening the switch. It has previously been proposed to use a Magnasphere switch, installed above a 5 door, as a direct substitute for a magnetic reed switch, to trigger an alarm when the 4 door is opened. Such a direct substitution of a Magnasphere switch for a reed switch still leaves the "door open" detection system vulnerable to tampering by a person who can gain access to the Magnasphere switch. In the module of the present invention, which is designed to be installed in a door frame, however, 5 (a) the Magnasphere switch is isolated from other components of the module by being embedded in a magnetically inert mass (for example, neoprene) which is mounted inside a box constructed from a non-magnetic material; and (b) the box containing the Magnasphere switch is made tamper-proof by the inclusion, in the box, of a micro-switch which is positioned so that (1) when 10 the box or module is closed by its non-magnetic "lid" or closure member, the microswitch is activated by the closure member, and (2) subsequent removal of the closure member will de-activate the micro-switch (which is an event that is sensed by the door monitoring circuitry, which then generates an alarm signal indicating that there has been an attempt to tamper with 15 the module). The mass containing the Magnasphere switch is positioned so that the base of the cup-shaped housing is adjacent to the closure member when the closure member has been applied to the box. The box may also contain an "end of line" module. (Most companies that 20 specialise in the provision of electronic circuits for use with locking arrangements have developed their own "end of line" module for use with such electronic circuits.) Leads fom the tamper-indicating micro-switch and from the Magnasphere switch (and also from the "end of line" module, if it is present) pass through an aperture (or through respective apertures) in a wall, or in the base, of the box, to be connected 25 to respective door monitoring circuits that are used for surveillance of the 5 position of the door (or the other moveable "element"). As noted above, the module is designed to be installed in a door frame within which the door moves (or to be installed in or on a fixed element, relative to which the moveable element may move). A magnet (preferably a disc magnet) or a 5 ferromagnetic disc, which need not be a circular disc, is then mounted on the the door. (If the module is installed in the head of the door frame, it is preferred that this magnet or ferromagnetic disc will have its upper face co-planar with the top edge face of the door.) This magnet or disc is mounted in a position such that, when the door is closed (or the moveable element is in its pre-determined position), the [0 magnet or ferromagnetic disc is aligned with the base of the cup-shaped housing of the Magnasphere switch, and is effective to "pull" the magnetic sphere of the Magnasphere switch towards the base of the housing, to the position in which the magnetic sphere contacts the electrode of the Magnasphere switch and activates (closes) the Magnasphere switch. (If the box is installed to monitor the position of 5 another form of moveable element, the magnet or ferromagnetic disc will be mounted on the moveable element in a position in which it is aligned with the base of the cup-shaped housing of the Magnasphere switch.) Opening the door (or moving the moveable element) will move the magnet (or ferromagnetic disc) out of alignment with the Magnasphere switch. The ferromagnetic bias within the Magnasphere 20 switch will then cause the magnetic sphere to move away from the base of the cup shaped housing - and thus away from the electrode of the Magnasphere switch - to open the Magnasphere switch. Opening the Magnasphere switch causes the generation of a signal that indicates that the door has been opened (or the moveable element has been moved). The position monitoring circuitry responds to that signal and 25 generates an alarm signal. Thus present invention provides a module for use in an electronic position 6 monitoring system which generates a signal when a moveable element has been moved from a predetermined position relative to a fixed element, said module comprising: a) a box constructed using a non-magnetic material, said box having at 5 least one side wall and a base; and b) a non-magnetic closure member for said box; and being further characterised in that said box contains c) a Magnasphere switch mounted in a magnetically inert mass; said Magnasphere switch having an internal metal housing and being o positioned so that the base of said internal metal housing of said Magnasphere switch is adjacent to said closure member when said box is closed by said closure member; and d) a micro-switch (preferably a lever arm micro-switch), positioned within said box so that, when said box is closed by said closure 5 member, said closure member activates said micro-switch. Normally, a separate magnet or ferromagnetic disc, to be positioned in or on said fixed element to close said Magnasphere switch when said moveable element is in said predetermined position, will be supplied with the module of the present invention. o A modified form of the module can be used to monitor the position of each leaf (door) of a double door installation. This modified form of the module contains two Magnasphere switches, each Magnasphere switch being in a position to monitor a respective one of the leaves, when each leaf has a respective magnet or ferromagnetic disc mounted in or on it, in alignment with the base of the internal 5 metal housing of its associated Magnasphere switch.

7 Embodiments of the present invention will now be described, by way of example only. In the following description, (a) the application of the invention to door monitoring will be featured (because the need to provide more effective door monitoring was the stimulus for the 5 present invention); and (b) reference will be made to the accompanying drawings. Brief description of the drawings. Figure 1 is a schematic side view - partly sectional - of a module constructed in accordance with the present invention, installed in the head of a door frame. 0 Figure 2 is a partly schematic perspective sketch showing the arrangement of the components of the module illustrated in Figure 1. Figure 3 is a schematic side view of a module, in accordance with the present invention, mounted in the head of a door frame of a double door installation. Detailed description of the illustrated embodiments. .5 The module shown in Figures 1 and 2 consists of a box 10 of a non-magnetic material (for example, aluminium or an aluminium alloy, or - and this is the present inventor's preferred material - non-magnetic steel). The box 10 has side walls 11, end walls 12 and a base 13. The end walls 12 are planar walls, each of which has a respective planar flange 14 extending (a) at right angles to the plane of 0 its associated end wall, and (b) from the edge of the end wall that is remote from the base of the box. The flanges 14 assist in the mounting of the box within the head 15 of a door frame. A closure member (a lid) 16 fits over the open face of the box, that is remote from the base 13, and over the flanges 14. Preferably, the box is mounted in the door frame head 15 so that, when the closure member 16 is 8 applied to the box, the lower face of the closure member 16 is (as shown in Figure 1) co-planar with the lower face of the door frame head 15. The box 10 shown in Figures 1 and 2 has the preferred construction of the box of the present invention. However, the side walls 11 and the end walls 12 need not 5 be planar walls. Although it is not preferred, if the box is made by moulding a plastic material, it may have a single (circular or oval) side wall, or the box may be irregularly shaped. In the illustrated embodiment of Figures 1 and 2, a Magnasphere magnetic switch 20, embedded in a block 21 of neoprene (any other suitable non-magnetic support 0 medium may be used instead of neoprene) is mounted within the box 10 so that, when the closure member 16 is applied to the box, the base of the Magnasphere switch (that is, the covering of the base of the internal cup-shaped housing of the Magnasphere switch) is adjacent to the closure member. Leads 22 extend from the Magnasphere switch 20, through the neoprene block 21, to leave the box 10 5 through an aperture 23 in one of the side walls 11, thence to be connected to a remote monitoring circuit (not shown in the drawings) for the Magnasphere switch. That monitoring circuit will normally include an alarm signal generator. The blpck 21 of a magnetically inert material is used to provide support for the Magnasphere switch (which is a small component) and to facilitate its correct 20 mounting within the box 10. The box 10 also contains a micro-switch 30. In the illustrated embodiment, the micro-switch 30 is the preferred lever type micro-switch, but a plunger type micro-switch may be used. The micro-switch 30 is mounted on a shelf 31 so that, when the closure member 16 is applied to the box 10, the micro-switch 30 is 9 activated. Leads from the micro-switch 30 leave the box 10 through an aperture 33 in one of the side walls 11 of the box. An "end of line" module 25 is also included in the embodiment illustrated by Figures 1 and 2. Leads from the end of line 25 leave the box 10 through an 5 aperture 26 in one of the side walls 11 of the box 10. When, as shown in Figure 1, the box 10 is mounted within the head 15 of a door frame, the door 17 mounted within that door frame will have a magnet or a ferromagnetic disc 18 mounted in or on the top of the door 17. Preferably, the top surface of the magnet 18 (or the ferromagnetic disc 18) is co-planar with the 10 top edge face 19 of the door 17. The magnet or ferromagnetic disc 18 is positioned in or on the door 17 so that, when the door is closed, the magnet or disc 18 is closely adjacent to the base of the Magnasphere switch 20. If a magnet 18 is used, provided the magnetic field established by the magnet 18 is sufficiently strong, the distance between the top edge face of the the door 17 and the base of the 15 Magnasphere switch 20 is not critical (provided the magnetic field of the magnet 18 is sufficient to move the magnetic sphere of the Magnasphere switch to the base of the internal housing of the Magnasphere switch, to contact the electrode of the Magnasphere switch and close the switch. However, if a ferromagnetic disc 18 (which, as noted above, need not be a circular or oval disc) is used, the distance 20 between the top edge face of the disc 18 and the base of the Magnasphere switch must not exceed the maximum value, specified by Magnasphere Corp., for successful operation of the Magnasphere switch. From the literature supplied by Magnasphere Corp., that spacing is 1/16 inch, which is approximately 1.4 mm. When the door 17 is "closed" (as shown in Figure 1), the magnetic sphere of the 25 Magnasphere switch 20 is at the base of the cup-shaped internal metal housing of 10 the Magnasphere switch. In this position, the magnetic sphere connects, electrically, the electrode and the internal housing of the Magnasphere switch. However, when the door 17 is opened, or a magnet or ferromagnetic material is brought close to the. Magnasphere switch 20 (for example, in an attempt to maintain the closure of 5 the switch as the door 17 is opened), the magnetic sphere of the Magnasphere switch will be deflected from its position at the base of the internal housing, and the electrical contact between the electrode and the housing will be broken. This break in contact is detected by the circuit that is monitoring the Magnasphere switch, and the appropriate action and/or alarm is initiated. 10 This illustrates a particular benefit of the Magnasphere magnetic switch over the conventional magnetic reed switch. If, in the module of the present invention, the Magnasphere switch should be replaced by a conventional magnetic reed switch, the status of that reed switch could be maintained in its "closed circuit" configuration by a "defeat magnet", brought alongside the magnetic reed switch, 15 as the door 17 is opened. Another benefit is the smaller size of the Magnasphere switch. If the closure member 16 should be removed from the box 10, with the intention of tampering with the components of the module, the micro-switch 30 will be de activated. The monitoring circuit of the micro-switch 30 will see the open circuit 20 and will generate the designated tamper signal, so that appropriate action can be taken to maintain the security of the room to which access is via the door 17. In most double door installations, it is normal practice for one of the leaves to be. fixed (by being bolted) and for the other leaf to be openable. However, this practice is not always followed, and even in a secure room having a double door installation, 25 there will be instances when both leaves are openable. Accordingly, there will be 11 times when it is necessary to monitor the position of each of the leaves of a double door installation. Figure 3 shows how two spaced apart Magnasphere switches in a single box 10 can be used to monitor, individually, the leaves 17 of a double door installation. In 5 Figure 3, components which are the same as the components of the module depicted in Figures 1 and 2 have been given the same reference numerals. Additional explanation of the operation of the embodiment illustrated by Figure 3, therefore, is unnecessary. It should be apparent that the present invention is not limited in its application to 0 locations where security is paramount (although security needs stimulated the conception of the present invention). Engineers will appreciate that the embodiments described above and illustrated in the accompanying drawings are illustrative embodiments only, and that variations of, and modifications to, the illustrated embodiments may be made without 5 departing from the present inventive concept.

Claims (5)

1. A module for use in an electronic position monitoring system which generates a signal when a moveable element has been moved from a predetermined position relative to a fixed element, said module comprising: a) a box constructed using a non-magnetic material, said box having at least one side wall and a base; and b) a non-magnetic closure member for said box; said module being further characterised in that said box contains c) a Magnasphere switch mounted in a magnetically inert mass; said Magnasphere switch having an internal metal housing and being positioned so that the base of said internal metal housing of said Magnasphere switch is adjacent to said closure member when said box is closed by said closure member; and d) a micro-switch, positioned within said box so that, when said box is closed by said closure member, said closure member activates said micro-switch.

2. A module as defined by claim 1, including a second Magnasphere switch in said box; said second Magnasphere switch being spaced from said first mentioned Magnasphere switch; said second Magnasphere switch being mounted in a respective magnetically inert mass; said second Magnasphere switch having an internal metal housing and being positioned so that the base of said internal metal housing of said second Magnasphere switch is adjacent to said closure member when said box is closed by said closure member; whereby said module may be mounted in the head of a door frame of a double door installation, in a position in which each Magnasphere switch may be used to monitor the position of a respective leaf of said installation. 13

3. A module as defined by claim 1 or claim 2, including an end of line module within said box.

4. A module as defined by claim 1, claim 2 or claim 3, including at least one disc magnet or ferromagnetic disc, supplied separately, for mounting on, or in an edge region of, said moveable element.

5. A module for indicating when a moveable element has been moved from a predetermined position relative to a fixed element, as defined by claim 1, substantially as hereinbefore described with reference to the accompanying drawings. Dated this thirtieth day of June, 2010. TREVOR DAVID LEISK by his Patent Attorneys DAVIES COLLISON CAVE