WO2014042918A2 - Antenna system and method for defining a detection zone - Google Patents

Description

ANTENNA SYSTEM AND METHOD FOR DEFINING A DETECTION ZONE

Background

Non-compliance with recommended hygiene protocols such as washing or otherwise sanitizing hands before and after patient contact is thought to be a significant contributor in the spread of Healthcare Acquired Infections (HAI's). Each HAI adds cost and, in some instances, time to stays in hospitals and some medical care insurers, such as, e.g., Medicare, have indicated that they will not reimburse healthcare providers for healthcare expenses that are the direct result of at least some HAI's.

Monitoring compliance with hygiene protocols is, as a result, becoming increasingly important to assist health care facilities with measuring compliance with their hygiene protocols. Certain compliance systems, such as the system described in US Publication No. 201 1/0148586 to Anderson et al. entitled Hygiene Monitoring Systems and Methods, rely on the detection of an entry or exit from a defined zone created within or proximate to an area of interest. In certain useful implementations, these zones are defined using electromagnetic fields.

Summary

While electromagnetic fields can provide a suitable detection zone under certain circumstances, it has been found that energy transmitted by the magnetic field is negatively impacted by mobility, orientation, shape, and material construction of objects within an area of interest. For example, a hospital bed may include metallic and electronic elements that distort or modify magnetic fields generated from a coil antenna located e.g., underneath a mattress. The distortions require undesirable levels of power supply to maintain the proper zone boundaries and can adversely affect the ability of a detection system to properly register an approaching object or person.

The present disclosure provides a modularized system of antennas that allows for more precise control of the generated field(s) to maintain a consistent boundary or detection zone, accommodates irregularities or breaks in the boundary or detection zone, keeps power requirements to a minimum, and provides for the safety of the individuals that may be within or pass through the detection zone. In particular, the use of two or more antennas to define the zone can minimize the amount of power necessary to drive the system and avoid or capitalize on the field modifying effects of objects in the area of interest. The antenna modules of the present disclosure may be attached to any object of interest in a hospital (or any other facility) and may be configured to define a precise detection zone around that object. The adaptability of these systems allows for customization and reliable detection not consistently possible with other electromagnetic systems.

In one aspect, the present disclosure provides a detection system that utilizes two or more antenna modules to define a two or three dimensional area of interest to be sensed using an electromagnetic field. The antenna modules each consist of a loop or other type of antenna configuration and can be connected to a driver either in series or parallel. The modules may be mounted to the surface of an article in such a way as to use the characteristics of the mounted surface to enhance the field generated by the antenna(s). In certain potentially advantageous embodiments, the module is mounted to the surface of an article such that the plane of the antenna is orthogonal to the mounting surface.

In another aspect, the present disclosure provides a system of antenna construction that allows for loops, coils, or wires to be added or removed to a module to alter the field characteristics or strength of the generated electromagnetic field(s).

In yet another aspect, the present disclosure provides a system of antenna construction that allows for the introduction of materials, such as ferrous cores, to be added within the antenna module to manipulate the generated electromagnetic field to a desired form.

The present disclosure provides a method for defining a detection zone, the method comprising: providing an antenna module, the module comprising a coil antenna having a plane; securing the module to a surface of an article such that the plane of the coil antenna creates a non-zero angle with respect to the surface; driving the coil antenna to generate an electromagnetic field, the field defining at least a portion of a boundary around the article.

The present disclosure also provides a system comprising a hospital bed having one or more boundary surfaces, an antenna module attached to a boundary surface, wherein the antenna module comprising an antenna having a plane, and wherein the plane of the antenna forms a non-zero angle with the boundary surface. In some embodiments, system comprises a plurality of antenna modules.

The terms "comprises" and variations thereof do not have a limiting meaning where these terms appear in the description and claims.

The words "preferred" and "preferably" refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention.

As recited herein, all numbers should be considered modified by the term "about".

As used herein, "a," "an," "the," "at least one," and "one or more" are used interchangeably. Thus, for example, a pressure pad comprising "a" protrusion can be interpreted as a pressure pad comprising "one or more" protrusions.

Also herein, the recitations of numerical ranges by endpoints include all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

The above summary of the present invention is not intended to describe each disclosed embodiment or every implementation of the present invention. The description that follows more particularly exemplifies illustrative embodiments. In several places throughout the application, guidance is provided through lists of examples, which examples can be used in various combinations. In each instance, the recited list serves only as a representative group and should not be interpreted as an exhaustive list.

Brief Description of the Drawings

The invention will be further described with reference to the drawings, wherein corresponding reference characters indicate corresponding parts throughout the several views, and wherein:

Figure 1A depicts a top down view of an antenna coil according to an embodiment of the present invention.

Figure IB depicts a side view of the antenna coil of Figure 1A.

Figure 2A depicts a top down view of an antenna coil according to an embodiment of the present invention.

Figure 2B depicts a side view of the antenna coil of Figure 2A.

Figure 3 depicts a side view of a multi-coil antenna configuration according to an embodiment of the present disclosure.

Figure 4 depicts a perspective view of an antenna module according to an embodiment of the present disclosure.

Figure 5A is a cross-sectional view of the module of Figure 4.

Figure 5B is another cross-sectional view of the module of Figure 4.

Figure 5C is another cross-sectional view of the module of Figure 4.

Figure 6A-D depicts cross-sectional views of antenna modules coupled to a surface of an object of interest.

Figure 7 depicts a cross-sectional view of another antenna modules coupled to a surface of an object of interest.

Figure 8 depicts a cross-sectional view of another antenna modules coupled to a surface of an object of interest.

Figures 9A and 9B depict top and side views of a representative magnetic field generated by an antenna module relative to a surface of an object of interest.

Figures 1 OA and 1 OB depict top and side views of another representative magnetic field generated by an antenna module relative to a surface of an object of interest.

Figures 1 1A and 1 IB depict top and side views of another representative magnetic field generated by an antenna module relative to a surface of an object of interest.

Figure 12 depicts a side view of a representative magnetic field generated by another embodiment of an antenna module.

Figure 13 is a schematic representation of two antenna modules connected in series according to an embodiment of the present disclosure. Figure 14 is a schematic representation of a plurality of antenna modules used in creating multiple detection zones according to an embodiment of the disclosure.

Figures 15A-C depict a plurality of representative magnetic fields generated relative to a hospital bed according to an embodiment of the disclosure.

Figures 16A-C depict a plurality of representative magnetic fields generated relative to a hospital bed according to another embodiment of the disclosure.

Figure 17 depicts a plurality of representative magnetic fields generated relative to a hospital bed according to another embodiment of the disclosure.

Figures 18A and 18B depict the use of two or more antenna modules to generate multiple detection zones according to an embodiment of the present disclosure.

Figure 19 depicts an antenna module system of the present disclosure coupled to a doorway.

Figure 20 depicts an antenna module system of the present disclosure generating multiple detection fields coupled to a doorway.

Figure 21 depicts an antenna module system of the present disclosure generating multiple detection fields and coupled to a desk.

Layers in certain depicted embodiments are for illustrative purposes only and are not intended to absolutely define the thickness, relative or otherwise, or the location of any component. While the above- identified figures set forth several embodiments of the invention, other embodiments are also

contemplated, as noted in the description. In all cases, this disclosure presents the invention by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the invention. Detailed Description of Illustrative Embodiments

The present disclosure provides a system for generating and defining a detection zone at least partially around an object of interest, such that approach or proximity to the object may be detected or registered. In particular, the systems disclosed herein generate and maintain one or more magnetic fields via antenna modules attached to the surface of the object. Entry or exit from the magnetic field of a credential (e.g., a badge with a transceiver) may be used to track encounters within a facility or eventually track compliance with protocols. The credentials used in systems as described herein may take a wide variety of forms. In some embodiments, the credentials may be provided in the form of a badge, tag, label, display device, personal digital assistant (PDA), cell phone, pager, or any other article that is carried by or otherwise attached to the selected person or piece of equipment as they move into and out of detection zones in a location (e.g., a health care facility) in which the systems described herein are used. A credential is typically able to detect the presence of a magnetic field and either transmits the detected encounter via a communication module or stores the encounter in on-board memory. One or more antenna modules may be coupled to a zone controller via a standardized interface. The zone controllers as described herein may preferably include, in various embodiments, a power source for driving the antenna modules to create a magnetic field, a communication device capable of transmitting and/or receiving data and memory that is operably connected to the communication device to store received data and/or transmit stored data as a part of the operation of the system. The operable connection between the memory and the communication device, as well as the power source and the antenna module, may typically be performed by a controller that is also preferably resident on or in the zone controller. Examples of some potentially suitable controllers may include, e.g., an Application Specific Integrated Circuit (ASIC) state machine, a gate array, a microprocessor, a microcontroller, etc. The controller in zone controller may also, in some embodiments, be used to control operation of the zone.

The zone controllers of the systems described herein are also preferably configured to define one or more patient zones, where the patient zones define one or more areas in which entry into and/or exit of other components from the patient zone (such as a credential) can be detected.

By "define" as used in connection with the zones defined by the systems described herein, it is meant that a system preferably includes the components (e.g., hardware, processors, software, sensors, transducers, etc.) required to establish, form, emit, etc. the an electromagnetic detection zones described herein. While the zone controller and antenna module may, in some embodiments, be provided as a one- piece integrated unit contained within a single housing, in other embodiments, the system may include two or more components (e.g., power supply and antenna coil) in a separate antenna module housing.

The detection zones defined by the systems described herein may preferably be large enough to contain a object of interest such that physical contact with the object is typically not possible without a detectable entry into the zone, although in some instances as described herein, the size of the zone may be reduced to, e.g., facilitate movement of the object within a healthcare facility, etc. In other embodiments, multiple detection zones may be created by cooperation of the zone controller and the antenna modules.

An embodiment of an antenna 10 for generating an electromagnetic field for use in defining a detection zone is depicted in Figures 1A and IB. The antenna 10 comprises a conductive coil 1 1 arranged in an elongated loop about a center 12, otherwise known in the art as a loop antenna. The coil includes a conductive material, preferably copper, and is typically insulated. The number of loops, as well as the configuration and geometry thereof, can be adjusted as desired to modify the characteristics of the field generated. In particularly suitable embodiment, the loop includes at least a 4: 1 length to width ratio and in other embodiments at least a 10: 1 length to width ratio. Typically, the center opening 12 has a minimum dimension of 0.125 inches, as measured from the innermost parallel sides of the conductive coil. The dimensions above are suitable for some implementations, but others may require different dimensions depending on the characteristics of the electromagnetic field. While antenna coils are particularly suitable for use in generating the electromagnetic field, other antenna constructions are also possible. The conductive coil 1 1 is coupled to a connector 13. The connector 13 couples the coil 1 1 to a zone controller (not shown). In some embodiments, power can be transferred via cable by a remote power source collocated with the zone controller. Any known manner of transmitting power is suitable for use with the present disclosure. Additional components of a loop antenna may be found in, for example, US Publication No. 2011/0281535 to Low et al., entitled Controlling Field Distribution of a Wireless Power Transmitter.

Another antenna embodiment 20, wherein the conductive coil is formed on or integral with a substrate, is depicted in Figures 2A and 2B. The conductive coil 21 can be formed on the substrate 24 by processes such as etching, plating, additive deposition or die stamping. Though more rectangular in shape, the conductive coil 21 includes a central core 24 that separates the innermost loop elements. A connector 23 may also be provided coupled to the substrate. Printed circuit boards (PCBs), typically including chips or chip modules, are particularly useful substrates. Additional antenna constructions on substrates are known in the art and may be found, for example, in US Patent Nos. 7,928,847 to Murdoch et al., US 5,608,417 to De Vail, and US Publication No. 2010/0181385 to Brod.

Advantageously, the antennas may be stacked or otherwise combined to provide different electromagnetic field characteristics (e.g., strength). Figure 3 shows a stack 30 of antenna coils 31. The antennas 31 are electrically coupled via conductive material or other means of coupling antenna coils known in the art. The orientation of the antennas relative to each other may enhance or inhibit the magnetic field, depending upon the constructions of the individual antennas. Each antenna coil can be configured to generate a similar electromagnetic field or certain coils may generate different fields.

Though the combined antenna 30 is depicted as stacked in the vertical direction, it is contemplated that the antenna coils 31 could be arranged end to end, flared out, or any configuration desired to generate the required field. For example, each antenna coil of the plurality of antenna coils may be oriented at a different angle relative to a surface of the object of interest (see e.g., Figure 6D).

In particular embodiments useful in the present disclosure, an antenna module includes one or more antennas secured inside an antenna housing. A suitable housing 105 for use in antenna module 100 is depicted in Figures 4 and 5A-5C. The housing 105 includes a base 1 10 and a tapered or contoured shell 1 12. At least a portion of the base 1 10 is preferably planar or substantially planar to allow coupling to an object of interest. Such coupling can be accomplished with any known mechanical fastener (e.g., adhesive, tape, clips, etc.). In the depicted embodiment, the shell 1 12 is curved around the ends of the antenna 120, but the shell 1 12 can include a multitude of shapes and geometries depending, for example, on the geometry of the antenna 1 12. Rails, guides, or like structures, and/or mechanical fasteners, may also be used to secure and specifically orient the antenna 120 in the housing 100.

The shell 1 12 and the base 1 10 are preferably made from a non-conductive and/or non metallic material. As described below, components of the housing 105 may be made from conductive or ferrous materials to affect the characteristics of the magnetic field generated by the antenna. In certain embodiments, either or both of the base 1 10 and shell 1 12 may comprise conductive or ferrous materials. Turning to Figures 5A-5C, an antenna 120 is secured in the housing and communicatively coupled to a zone controller via connector 130. The connector 130 is configured to communicate with the zone controller to facilitate transmission of at least power between the zone controller and the antenna module. The connector 130 may be fabricated to facilitate wireless and/or wired communication between the zone controller and the antenna module using, e.g., a cable, port, USB, Bluetooth, IR or other communication link. Other suitable means of coupling the zone controller to the antenna module will be apparent to those skilled in the art.

As described above, the zone controller typically includes a controller, a memory, a

communication device (i.e., transceiver), a power source, and a means for transmitting power to the antenna. In some embodiments, all of the components of the zone controller 130 are provided remote from the antenna housing 105. In alternative embodiments, some or all of these components are located within or on the antenna housing 105. For example, the housing may contain a power source (e.g., battery) necessary to drive the antenna to generate a magnetic field. The power source may be activated, via wired or wireless signal transmission, by components in the zone controller.

The antenna module may be secured in the housing in a multitude of orientations according to the desired characteristics of the magnetic field. Figures 6A-6C depict antennas oriented relative to the housing base 1 10 and a mounting surface 200 of an object of interest (e.g., a hospital bed). In a particularly suitable embodiment, an antenna 120 is oriented within the housing 105 such that a reference plane 122 of the antenna 120 is orthogonal to both the base 1 10 and the mounting surface 200. The normal magnetic field 124 in this embodiment will be initially generated in a direction substantially parallel to the mounting surface. The reference plane 122 is typically defined by two or more points on the antenna coil, such that the reference plane 122 will typically be coplanar with a major surface of the antenna substrate. Figures 6B and 6C demonstrate other orientations of the antenna 122, wherein a reference plane 122 and the mounting surface 200 form a non-zero angle 125. The angle 125 can be adjusted or selected based on the desired characteristics of the magnetic field, as well as the

characteristics of the object of interest. The present inventors have found that orienting the antenna at a non-zero angle relative to the mounting surface results in less unwanted interference from the mounting surface and potentially more control over the characteristics of the magnetic fields defining the detection zone.

The non-zero angle between the reference plane 122 and the mounting surface is preferably, in certain circumstances, about 90 degrees. In some embodiments, the angle is at least 60 degrees, in other embodiments at least 30 degrees, and in other embodiments at least 10 degrees, and in yet other embodiments at least 5 degrees.

In some embodiments (not shown), the housing 105 may include a mechanism, such as a lever, a rotatable dial, or other like structures, to adjust the orientation of the antenna relative to the base 1 10 and/or the mounting surface 200. In other embodiments, a portion of the housing 105 (e.g., the shell 1 12) may be removable to allow a user to access the antenna within. In other embodiments, an antenna module can include one or more conductive, metallic, and/or ferrous materials to manipulate or affect the field generated by the antenna. With reference to Figure 7, a housing 300 includes a conductive, metallic, and/or ferrous structure 325 designed to absorb, modify, or deflect portions of the field generated by antenna 320. Alternatively or in addition, an antenna module housing 400 may include an antenna 420 provided with a ferrous core 425 within the center of a loop antenna (Figure 8). Potential effects of these structures may be appreciated with reference to Figures 1 1A, 1 1B, and 12.

Turing now to Figures 9- 12, the fields generated by certain antenna modules relative to a variety of objects of interest will be discussed. As will be appreciated, generated field drawings are

representative and do not represent actual contour of the magnetic fields. Figures 9A and 9B depict an antenna module 100 with the antenna 120 oriented in a plane perpendicular to the mounting surface 200. The housing 105 does not include integrated conductive, metallic, and/or ferrous materials. In this example, the mounting surface 200 includes a construction which does not affect magnetic field characteristics (e.g., wood, plastic, etc). In such circumstances, the generated field 150 may be substantially uniform on either side of the antenna 120.

As shown in Figures 10A and 10B, an object of interest and/or the mounting surface may impact, often adversely, the generated magnetic field. Impact to generated fields (e.g., strength and shape) may occur when fields are generated on or near certain conductive, metallic, ferrous materials or constructions. The extent of impact to the field will be dependent upon material composition, amount of material, and/or form of material. For instance, when mounted to a patient bed in a healthcare facility, a bed containing electronics, chassis grounding, and shielding may result in a generated field different than a simple mechanical bed with no electronics or a patient chair.

Figures 10A and 10B depict an antenna module 100 with the antenna 120 oriented in a plane perpendicular to the mounting surface 210 within a housing 105 that does not include integrated conductive, metallic, and/or ferrous materials. Unlike mounting surface 200, the mounting surface 210 includes a material or construction which does affect field characteristics (a conductive, metallic, ferrous material, etc). In these circumstances, the generated field 150 may be directed substantially away from the mounting surface side of the module 100. A similar effect on the generated field may be obtained by including field affecting materials in the housing (Figure 11A and 1 IB). Figure 12 demonstrates a potential result of manipulating both antenna 120 orientation relative to the mounting surface and including field affecting materials with the module housing. As can be appreciated, the field may be directed in any fashion relative to the object of interest according to the field altering characteristics (e.g., antenna orientation, composition of the object, etc.) of both the module and the object.

Advantageously, two or more modules may be connected in series to define a particular detection zone. Figure 13 depicts two antenna modules 510, 520 each including a respective connector 512, 522 coupled to a communication link, in this embodiment cable 540. The cable 540 serves to connect both antenna modules 510, 520 to a zone controller 530. The zone controller 530 can accordingly control when power is supplied to multiple modules, potentially using a single power source. The use of multiple antenna modules controlled by a single source to define a detection zone potentially allows for more precise control of the contours of the zone and a decreased amount of power necessary to maintain the zone.

The modules 510 and 520 can have substantially similar or different constructions. In certain embodiments, it may be advantageous to couple to two or more modules that create a substantially similar magnetic field in series. This allows for potentially uniform boundaries of the detection zone about the object of interest. In other embodiments, it may be desirable to couple disparate modules together. For example, modules generating different field strengths may be connected in series to define non- symmetrical boundaries about a doorway. In any event, the antenna modules are preferably standardized so that the user may select and generate the magnetic fields or series of magnetic fields so desired.

In yet other embodiments, a mix of similar and disparate fields may be generated by a single zone controller. Figure 14 depicts a system 600 including plurality of antenna modules in communication with a zone controller 650. A first set of modules (610, 620) are connected in series to define a first detection zone 660. A second set of modules (630, 640) are connected in series to define a second detection zone 670. The first set of modules (610, 620) may generate magnetic fields having similar characteristics (e.g., strength and shape) to define zone 660. The second set of modules (630, 640) may generate fields sharing characteristics different from the fields in the first detection zone 660. The module connector on each module preferably contains at least one pass through to allow multiple sets of modules to be connected to multiple drivers using a single cable. The zone controller 650 could include multiple transmission channels or drivers to separately control or supply power to each zone (660, 670). The use of distinct magnetic fields to create multiple detection zones is explored in more detail below with respect to Figures 18A and 18B.

Figures 15A through 15C depict one exemplary implementation of defining a patient zone using multiple magnetic fields generated by the antenna modules of the present disclosure. A pair of modules 710 and 712 is placed on either side of a hospital bed 720. The modules 710, 712 generate a pair of fields 71 1, 713 that can be sensed by an appropriate credential. Receipt or detection of the field by the credential and/or the module can determine the credential's approach to the patient bed 720. In this embodiment, the generated fields define a portion of the periphery or boundary of the bed 720. A credential approaching the head or the foot of the bed may not pass through the detection zone.

Figures 16A through 16C depict another deployment of an antenna module system on a patient bed 720. As depicted, four antenna modules (710, 712, 714, and 716) generating magnetic fields of lower strength (71 1, 713, 715, 716) are placed in pairs on either side of a patient bed 720. This allows for a detection zone comprising the lower strength fields to remain in a consistent area with respect to the patient bed 720, regardless of the articulation or orientation of the bed 720. The modules may be connected in series or operate independently. Alternatively, a module may be coupled to and driven with the module on the same side of the bed 720. In another embodiment depicted in Figure 17, a series of antenna modules (710, 712) are mounted on the side of a patient bed 720 and generate fields (71 1,713) having similar characteristics (e.g., size and shape). Additional modules (714,716) are placed at the head and foot of the bed 720, and generate fields (715, 717) sharing characteristics different from fields 71 1 and 713. This particular arrangement of modules defines a substantial portion of bed periphery, and can accordingly detect approaches from the head or the foot of the bed. As should be recognized, all modules used to define a substantial periphery could share similar field characteristics.

The antenna modules of the present disclosure may also be arranged around an object of interest to detect a series of events by, for examples, creating multiple boundaries. In one embodiment as depicted in Figures 18 A and 18B, a first set of modules (810, 812, 814, and 816) is placed on or near exterior surfaces of a patient bed 820 to generate a series of fields (811, 813, 815, 817) that, when encountered by a credential, indicate an approach to the patient in bed 820. A second set of modules (830, 832, 834, 836) is placed internal to the first set and generate fields (831, 833, 835, 837) that, when encountered by a credential, indicate close proximity to or contact with the patient. Both sets of modules may use the same cable and may be connected to the same zone controller.

The use of multiple antenna modules to define a detection zone (e.g., a patient zone) can be particularly advantageous. One potential advantage of disclosure is that a single zone controller with a pre-defined output power may drive multiple configurations of modules, when deployed in series, where the number of modules and the field strength of the individual modules can vary depending on the module selected and its placement on the object of interest. This gives the user additional control of the contours and boundaries of the detection zone. Another potential advantage of the disclosure is that the overall power required to generate a detection zone on the periphery of an object containing conductive, metallic, and/or ferrous materials may be less than the power required to generate the same field with a single antenna at the center of the object. The design of the antenna modules can either minimize the consequences of the effects on generated field or capitalize on those effects to create the desired contour and/or boundary of the detection zone.

The modular systems of the present disclosure may also be used to define detection zones around or within other objects or locations. For example, in Figure 19 an entry/exit system 900 may include a first antenna module 910 attached to a first side of a doorway 930, with a second module 912 serially coupled to the first module 910 and attached to the opposite side of the doorway 930. As in most embodiments described herein, both the first and second modules may be driven by a single zone controller 920. The modules 910, 912 may be configured to generate magnetic fields (91 1, 913) in the direction of the doorway opening so that breach by a credential, indicating entry or exit into the room, may be detected.

In other embodiments, multiple detection zones may be created around a doorway 930 (Figure

20) to detect both approach and breach. For example, modules 910 and 912 may be configured to detect a breach as described above. Modules 940 and 942 may be configured, with the same or different zone controller, to generate magnetic fields (941, 943) extending a certain distance from the doorway 930 to detect an approaching credential. Accordingly, the system would include a first zone including fields 941 and 943, and a second zone including fields 91 1 and 913. In yet other embodiments as exemplified in Figure 21, multiple detection zones (e.g., fields 1002, 1004, 1006, 1008, 1010) may be created around a desk 1000 or other structure.

The complete disclosures of the patents, patent documents, and publications cited herein are incorporated by reference in their entirety as if each were individually incorporated. Various modifications and alterations to this invention will become apparent to those skilled in the art without departing from the scope and spirit of this invention. It should be understood that this invention is not intended to be unduly limited by the illustrative embodiments and examples set forth herein and that such examples and embodiments are presented by way of example only with the scope of the invention intended to be limited only by the claims set forth herein as follows.

Claims

We claim

1. A method for defining a detection zone, the method comprising:

providing an antenna module, the module comprising a coil antenna having a plane;

securing the module to a surface of an article such that the plane of the coil antenna creates a nonzero angle with respect to the surface;

driving the coil antenna to generate a magnetic field, the field defining at least a portion of a boundary about the article.

2. The method of claim 1, wherein the article is selected from the group consisting of a bed, a wheelchair, and a doorway.

3. The method of claim 1, wherein providing an antenna module comprises providing two or more antenna modules connected in series.

4. The method of claim 1, wherein the antenna module comprises a conductive coil fabricated on a substrate.

5. The method of any of the previous claims, wherein the plane of the antenna is orthogonal to the surface.

6. The method of any of the previous claims, wherein the antenna module is coupled to a zone controller, the zone controller configured to drive the coil antenna.

7. A system comprising a hospital bed having one or more surfaces, an antenna module attached to a surface, wherein the antenna module comprising an antenna having a plane, and wherein the plane of the antenna forms a non-zero angle with the surface.

8. The system of claim 7, wherein a plurality of antenna modules are attached to two or more surfaces.

9. The system of claim 8, wherein the plurality of antennas are each configured to generate an electromagnetic field, the electromagnetic fields defining at least a portion of the periphery of the hospital bed.

10. The system of claim 7, wherein the plane of the antenna is orthogonal to the bed surface.