Patent Description:
The embodiments set forth herein relate, generally, to metal detection systems and, more specifically, to a metal detection system for use with a medical waste container.

Conventional medical practices and procedures typically involve the use of disposable articles and materials to maintain sterility and promote safety. Moreover, certain medical tools, instruments, and equipment may be sealed in disposable packaging to ensure sterility, or may otherwise employ disposable shields and/or covers. Thus, it will be appreciated that a relatively high amount of medical waste and trash can be generated during a complex medical procedure, such a surgical procedure where multiple medical devices, instruments, and tools are used and a high amount of disposable articles are consumed, such as gauze, tape, shields, table covers, drapes, tubing, padding, garments, and the like.

It will be appreciated that certain types of medical waste and trash generated during medical procedures can be extremely dangerous. By way of example, disposable articles contaminated with blood or human tissue may transmit infectious diseases to medical professionals, patients, or anyone involved in the handling and disposal of medical waste. Moreover, needles employed for drug administration, intravenous catheter insertion, and blood drawing are commonplace in the medical industry and are segregated from other types of medical waste and trash into so-called "sharps" containers.

While certain medical tools, instruments, and equipment are considered "disposable" and are discarded after one use, others can be re-used several times after being re-sterilized between medical procedures. By way of example, electrically-powered surgical tools may be decontaminated and re-sterilized in a high-pressure steam autoclave after use in a medical procedure. In order to facilitate multiple decontamination and sterilizations, re-usable tools are specially manufactured from robust materials and, thus, tend to be relatively expensive. Moreover, certain re-usable tools are designed to be lightweight to promote ease-of-use and improve handling, but may appear to be disposable to the untrained eye. Because of this, certain medical professionals, such as nurse's aides or cleaning staff members, may be unaware that certain medical tools are re-usable and should not be discarded with trash. Further, there is a tendency for inadvertent disposal of relatively small or lightweight objects that can become concealed in, around, or otherwise by larger objects, such as towel clips, scalpel handles or a needle concealed in a disposable surgical drapes.

In order to prevent inadvertent disposal of sharps and re-usable medical equipment along with other trash and medical waste, certain medical waste containers employ metal detectors adapted to alert a user of the presence of metallic objects, whereby an audible alarm typically sounds when metal is detected. However, medical waste metal detectors known in the art are often only designed to detect particular materials or certain types of objects, and may otherwise be unsuitable for use in certain environments. By way of example, certain medical waste metal detectors known in the art may be designed to detect small steel objects like needles and tend to be overly-sensitive which, in turn, frequently results in inadvertent activation of the alarm in response to transient movement of larger metal objects passing nearby, such as an IV pole. Further, known medical waste detectors may be designed to alert based on the presence of certain metals such as steel, but are unable to detect other types of metal frequently utilized in the medical industry, such as aluminum and titanium. Further still, known medical waste detectors may be unable to differentiate between a metallic object passing into the medical waste container, and a metallic object being subsequently removed from the medical waste container, and thus will unnecessarily alert when an inadvertently disposed metallic object is subsequently removed from the medical waste container.

For the foregoing reasons, there remains a need in the art for a metal detection system for medical waste containers that can identify inadvertently disposed metallic objects manufactured from different materials and which strikes a substantial balance between usability, functionality, and manufacturing cost while, at the same time, affording improved sensitivity and adaptability within different environments commonly encountered in the medical industry.

<CIT> discloses a known apparatus provided for detecting flatware, medical instruments and other metal content articles (objects) being put into a trash can.

<CIT> discloses an exemplary known metal detector approach. <CIT> discloses a known portable cart for containing medical waste, cmprising a metal detection system.

The scope of the invention is defined in appended claim <NUM>. In one embodiment, a detection system is provided for detecting disposal of metallic objects into an opening of a medical waste container. The detection system includes a detection indicator for indicating passage of metallic objects through the opening of the medical waste container. A pair of receive coils and a transmit coil spaced between the receive coils are provided. The coils are shaped for receiving waste therethrough adjacent to the opening of the medical waste container. A controller is provided in electrical communication with the coils. The controller is configured to generate a transmit signal and communicate the transmit signal to the transmit coil such that the transmit coil generates a magnetic field based on the transmit signal. The magnetic field induces voltage in each of the receive coils such that the receive coils each generate a receive signal received by the controller. The controller is further configured to generate a waveform based on both of the receive signals. The waveform has a baseline condition corresponding to absence of interaction of metallic objects with the magnetic field. The controller is still further configured to analyze the waveform with respect to a first detection threshold and a second detection threshold opposite to the first detection threshold with the baseline between the first detection threshold and the second detection threshold. The controller is further configured to activate the detection indicator in response to metallic objects passing through the coils based on the waveform exceeding the first detection threshold at a first time and exceeding the second detection threshold at a subsequent second time.

In another embodiment, a detection system is provided for detecting disposal of metallic objects into an opening of a medical waste container. The detection system includes a detection indicator for indicating passage of metallic objects through the opening of the medical waste container. A first receive coil, a second receive coil, and a transmit coil spaced between the receive coils are provided. The coils are shaped for receiving waste therethrough adjacent to the opening of the medical waste container. A controller is provided in electrical communication with the coils. The controller is configured to generate a transmit signal and communicate the transmit signal to the transmit coil such that the transmit coil generates a magnetic field based on the transmit signal. The magnetic field induces voltage in each of the receive coils such that the first receive coil generates a first receive signal and the second receive coil generates a second receive signal with both of the receive signals received by the controller. The controller is further configured to generate a waveform based on both of the receive signals. The waveform has a baseline condition corresponding to absence of interaction of metallic objects with the magnetic field. The controller is still further configured to analyze the waveform with respect to a first detection threshold and a second detection threshold opposite to the first detection threshold with the baseline between the first detection threshold and the second detection threshold. The controller is further configured to simultaneously analyze the receive signals and the waveform, and to activate the detection indicator in response to metallic objects passing through the coils based on predetermined changes occurring in the first receive signal and subsequent predetermined changes occurring in the second receive signal, and further based on the waveform exceeding the first detection threshold at a first time and exceeding the second detection threshold at a subsequent second time.

The detection system detects and alerts a user of disposal of metallic objects into an opening of a medical waste container, thereby significantly contributing to safety in handling trash and medical waste and affording increased opportunity for preventing inadvertent disposal of re-usable medical devices, instruments, and equipment while, at the same time, reducing the cost and complexity of manufacturing, assembling, and using medical waste container metal detection systems that provide users with improved functionality and usability.

With reference now to the drawings, wherein like numerals indicate like parts throughout the several views, a mobile cart is generally shown at <NUM> in <FIG>. The mobile cart <NUM> includes a base <NUM> supported by a plurality of wheels <NUM> employed to support the base <NUM> and facilitate mobility. A pedestal <NUM> is operatively attached to and extends above the base <NUM> (see <FIG>). The pedestal <NUM> supports a mount, generally indicated at <NUM>. In another embodiment, one or more additional pedestals <NUM> (not shown) can be added to improve the stiffness and reduce the deflection of the mount <NUM> when external loading is applied to the mount <NUM> during use. The mount <NUM> has a generally rounded-rectangular profile and defines a correspondingly-shaped aperture <NUM> shaped to accommodate a medical waste container <NUM> (see <FIG>). However, it will be appreciated that the mount <NUM> and/or aperture <NUM> could have any suitable profile.

The medical waste container <NUM> may be removably attachable to the mount <NUM>. The medical waste container <NUM> has an opening <NUM> secured adjacent to the aperture <NUM> of the mount <NUM>. To that end, the mobile cart <NUM> may include one or more securing features, generally indicated at <NUM>, employed to releasably secure the medical waste container <NUM> to the mount <NUM>. In the representative embodiment illustrated herein, the medical waste container <NUM> is realized as a bag manufactured from plastic and configured to receive waste therein, such as garbage, trash, medical waste, and the like. However, as will be appreciated from the subsequent description below, the medical waste container <NUM> could be of any suitable type and could be configured in any suitable way sufficient to receive any type of waste. By way of non-limiting example, the medical waste container <NUM> could be realized with a conventional "garbage can" with a rigid body and with or without a disposable bag. The medical waste container <NUM> may be transparent to facilitate retrieval of inadvertently disposed metallic objects, and/or may be tinted certain colors corresponding to the type of medical waste intended to be contained therein.

The mobile cart <NUM> and/or the medical waste container <NUM> employs a detection system, generally indicated at <NUM>, according to one embodiment, for detecting disposal of metallic objects into the opening <NUM> of the medical waste container <NUM>. In some embodiments, the mobile cart <NUM> is optional. As shown schematically in <FIG>, the detection system <NUM> includes a detection indicator <NUM>, a first receive coil <NUM>, a second receive coil <NUM>, a transmit coil <NUM>, and a controller <NUM>. The detection indicator <NUM> is employed to indicate passage of metallic objects through the opening <NUM> of the medical waste container <NUM>. In one embodiment, the detection indicator <NUM> includes at least one audible and/or visual indicator, such as one or more speakers, displays, lights, and the like.

In the illustrated embodiment, the transmit coil <NUM> is spaced between the receive coils <NUM>, <NUM>. The coils <NUM>, <NUM>, <NUM> are shaped for receiving waste there through adjacent to the opening <NUM> of the medical waste container <NUM>, as described in greater detail below (waste container <NUM> not shown in <FIG>). The controller <NUM> is disposed in electrical communication with the coils <NUM>, <NUM>, <NUM>. The controller <NUM> is configured to generate a transmit signal <NUM> (see, e.g., <FIG>) and communicate the transmit signal <NUM> to the transmit coil <NUM> such that the transmit coil <NUM> generates a magnetic field based on the transmit signal <NUM>. The magnetic field, in turn, induces voltage in each of the receive coils <NUM>, <NUM> such that the first receive coil <NUM> generates a first receive signal <NUM> (see, e.g., <FIG>) received by the controller <NUM> and the second receive coil <NUM> generates a second receive signal <NUM> (see, e.g., <FIG>) received by the controller <NUM>. As is explained in greater detail below, the controller <NUM> is configured to generate a waveform <NUM> based on both of the receive signals <NUM>, <NUM>, and is further configured to analyze the waveform <NUM> to detect the passage of metallic objects through the opening <NUM> of the medical waste container <NUM> based at least partially on predetermined changes occurring in the receive signals <NUM>, <NUM>. As will be appreciated from the subsequent description below, "predetermined changes" of the receive signals <NUM>, <NUM> could include changes in amplitude, magnitude, frequency, and/or shift in phase.

With continued reference to <FIG>, the detection system <NUM> employed by the mobile cart <NUM> is configured to alert a user when a metallic object passes through the coils <NUM>, <NUM>, <NUM> into the opening <NUM> of the medical waste container <NUM>. In one embodiment, the detection system <NUM> includes a power source <NUM> (shown schematically in <FIG>) disposed in electrical communication with the controller <NUM> to facilitate operation of the detection system <NUM>. In one embodiment, the power source <NUM> is realized as a rechargeable battery. However, those having ordinary skill in the art will appreciate that the power source <NUM> could be of any suitable type or configuration sufficient to operate the detection system <NUM>.

As is depicted schematically in <FIG>, in one embodiment, the detection system <NUM> is operatively attached to and is supported by the mobile cart <NUM>. To this end, in one embodiment, the detection system <NUM> includes a coil support frame <NUM> arranged to support the coils <NUM>, <NUM>, <NUM>, as described in greater detail below. The coil support frame <NUM> is operatively attached to the mount <NUM> of the mobile cart <NUM> or other support structure, and may be manufactured from one or more components which cooperate to support, retain, or otherwise align the coils <NUM>, <NUM>, <NUM>. The coil support frame <NUM> may be fixed to the mount <NUM> with adhesive, non-metallic fasteners, and the like. The mount <NUM> may be formed of plastic to limit interference (for example, electromagnetic interference) with the operation of the coils <NUM>, <NUM>, <NUM> and the detection system <NUM>. It will be appreciated that the detection system <NUM> described herein could be used in a number of different applications, such as with mobile carts <NUM> without wheels <NUM>, with mounts <NUM> configured to walls or other immobile structures, and the like. By way of non-limiting example, the detection system <NUM> could employ a mount <NUM> adapted to be coupled to a wall so as to support the coils <NUM>, <NUM>, <NUM> vertically above a medical waste container <NUM> realized as conventional rigid garbage can with a disposable bag.

Referring now to <FIG>, the coil support frame <NUM> defines a passage <NUM> through which the medical waste container <NUM> is positionable to receive waste, as noted above. Here, the aperture <NUM> of the mount <NUM> is aligned with respect to the passage <NUM> of the coil support frame <NUM> such that objects passing through the opening <NUM> of the medical waste container <NUM> also pass through the aperture <NUM> of the mount <NUM> and the passage <NUM> of the coil support frame <NUM>. Thus, objects passing through the opening <NUM> of the medical waste container <NUM> pass sequentially through the first receive coil <NUM>, the transmit coil <NUM>, and the second receive coil <NUM> while being received in the medical waste container <NUM>. In one embodiment, the mount <NUM> has internal walls <NUM> spaced from the aperture <NUM> to define a hollow space, generally indicated at <NUM>, within which the coil support frame <NUM> is supported (see <FIG> and <FIG>). Here, the coils <NUM>, <NUM>, <NUM> are arranged between the internal walls <NUM> and the aperture <NUM> of the mount <NUM>.

In one embodiment, an isolation mechanism <NUM> is interposed between the mount <NUM> and the coil support frame <NUM> to isolate the coil support frame <NUM> from external force acting on the mount <NUM> (see <FIG> and <FIG>). More specifically, the isolation mechanism <NUM> prevents external forces acting on the mobile cart <NUM> or other supporting structure from deflecting or changing the position of the coils <NUM>, <NUM>, <NUM> relative to each other. It will be appreciated that external forces may occur during use in a number of different ways, such as by objects placed on top of the mobile cart <NUM>, people or objects "bumping" or otherwise engaging the mobile cart <NUM>, and the like. Here, the isolation mechanism <NUM> is advantageously positioned, arranged, and configured so as to isolate the coil support frame <NUM> from external forces acting on the mobile cart <NUM> in multiple directions, such as vertical (see <FIG>) and horizontal (see <FIG>). To this end, the isolation mechanism <NUM> may be realized as one or more discrete components coupled to the internal walls <NUM> and to the coil support frame <NUM> at one or more predetermined locations so as to dampen, attenuate, reduce, or otherwise inhibit the transmission of external force to the coil support frame <NUM>.

In the representative embodiment illustrated herein, the isolation mechanism <NUM> comprises a resilient member <NUM> operatively attached to the mount <NUM> and to the coil support frame <NUM>. However, those having ordinary skill in the art will appreciate that the isolation mechanism <NUM> could comprise any suitable type and/or arrangement of components sufficient to isolate the coil support frame <NUM> from external forces acting on the mount <NUM>. By way of non-limiting example, the isolation mechanism <NUM> could comprise various arrangements of resilient materials, elastomeric materials, cushioning materials, biasing members, and the like, such as foam or rubber.

Referring now to <FIG>, in the representative embodiment illustrated herein, the coil support frame <NUM> has a profile defined by a generally polygonal shape surrounding the aperture <NUM> of the mount <NUM> (see <FIG>). Here, the coils <NUM>, <NUM>, <NUM> each have a profile that is complimentary to the profile of the coil support frame <NUM>. Specifically, the coil support frame <NUM> and the coils <NUM>, <NUM>, <NUM> each have a profile defined as an irregular hexagon with at least one pair of parallel and diametrically opposed straight sides. However, it will be appreciated that the coil support frame <NUM> and/or the coils <NUM>, <NUM>, <NUM> could alternatively have a round or oval profile, or any other suitable profile. In the embodiment shown in <FIG>, the coil support frame <NUM> has two parallel and diametrically opposed straight sides 70A, 70B, two parallel and diametrically offset straight sides 70C, 70D, and two additional parallel and diametrically offset straight sides 70E, 70F. Here, sides 70C and 70E as well as sides 70D and 70F join at a vertex having an angle α1 which is greater than an angle α2 of a vertex between sides 70A and 70C, sides 70A and 70F, sides 70B and 70E, and sides 70B and 70D. Here, angle α2 is greater than <NUM>° and angle α1 is less than <NUM>°. Specifically, as shown in <FIG>, α2 is approximately <NUM>° and angle α1 approximately <NUM>°.

As explained in greater detail below, in one embodiment, the coils <NUM>, <NUM>, <NUM> of the detection system <NUM> are advantageously physically balanced with respect to each other so as to enhance sensitivity and detection accuracy in operation. To that end, in the representative embodiment illustrated herein, the coils <NUM>, <NUM>, <NUM> are supported in respective grooves <NUM> defined in the coil support frame <NUM>. The grooves <NUM> are arranged to support the coils <NUM>, <NUM>, <NUM> and, thus, effect physical balance through symmetry therebetween. Here, as best shown in <FIG>, and <FIG>, the coils <NUM>, <NUM>, <NUM> are aligned so as to be parallel with each other and are arranged so as to be co-axial with each other. Moreover, the coils <NUM>, <NUM>, <NUM> have a common profile with a common shape and common perimeter (see <FIG>), and the transmit coil <NUM> is spaced equidistantly between the receive coils <NUM>, <NUM>. In one aspect, each of the coils <NUM>, <NUM>, <NUM> includes the same number of turns of a conductive wire, such as copper (not shown in detail). In another aspect, each of the receive coils <NUM>, <NUM> includes at least fifty turns of conductive wire (not shown in detail). In another aspect, each of the receive coils includes at least twenty-five turns of conductive wire. It will be appreciated that coils <NUM>, <NUM>, <NUM> made from the same length of the same type and size of wire and positioned within the same electromagnetic environment will have the same electrical inductance, impedance, and capacitance. In one embodiment, transmit coil <NUM> could have a different number of turns and thus different electrical characteristics than receive coils <NUM>, <NUM>. Moreover, while the representative embodiment of the detection system <NUM> described herein and illustrated throughout the drawings employs a single transmit coil <NUM> arranged between the receive coils <NUM>, <NUM>, as will be appreciated from the subsequent description below, the detection system <NUM> could employ multiple transmit coils <NUM>, operating at the same frequency or at different frequencies, arranged between the receive coils <NUM>, <NUM> in various manners.

As shown in <FIG>, in one embodiment, the coils <NUM>, <NUM>, <NUM> are spaced from each other at a predetermined distance <NUM> between <NUM> and <NUM>. In another embodiment, the predetermined distance <NUM> is between <NUM> and <NUM>. In yet another embodiment, the predetermined distance <NUM> is advantageously <NUM>. However, those having ordinary skill in the art will appreciate that the predetermined distance <NUM> could be any suitable distance, and could be adjusted for specific application requirements, such as to accommodate medical waste containers <NUM> of different types, sizes, shapes, and/or configurations. Moreover, it will be appreciated that the coils <NUM>, <NUM>, <NUM> and the predetermined distance <NUM> are depicted schematically and/or illustratively throughout the drawings, are not drawn to scale, and are not intended to be used as a dimensional or spatial reference with respect to any other part of the detection system <NUM>, unless otherwise specified herein.

As noted above, the grooves <NUM> formed in the coil support frame <NUM> align and support the coils <NUM>, <NUM>, <NUM>. In the representative embodiment illustrated in <FIG>, the coil support frame <NUM> is formed as a unitary, one-piece component having an inner surface <NUM> and an outer surface <NUM> (see <FIG>), with the inner surface <NUM> defining the passage <NUM> and with the grooves <NUM> formed in the outer surface <NUM>. It will be appreciated that this configuration contributes to ease of manufacturing of the detection system <NUM> in that all of the coils <NUM>, <NUM>, <NUM> are supported by a common coil support frame <NUM> in respective grooves <NUM> arranged at the predetermined distance <NUM>. Put differently, this configuration effects the physical alignment of the coils <NUM>, <NUM>, <NUM> noted above in a simple, cost-effective manner. However, those having ordinary skill in the art will appreciate that the coil support frame <NUM> could be manufactured from or otherwise realized as any suitable number of components which cooperate to support the coils <NUM>, <NUM>, <NUM>. By way of non-limiting example, the coil support frame <NUM> could be realized as three discrete members each supporting a respective coil <NUM>, <NUM>, <NUM> and coupled together for concurrent movement. In some embodiments, the coil support frame <NUM> is relatively rigid so as to resist deflection, which helps to maintain the arrangement, orientation, and spacing of the coils <NUM>, <NUM>, <NUM> with respect to each other. Here, it will be appreciated that the rigidity of the coil support frame <NUM> and the isolation mechanism <NUM> each contribute to preventing deflection and/or relative movement of the coils <NUM>, <NUM>, <NUM> during use.

Referring now to <FIG>, the coil support frame <NUM> of <FIG> is shown supporting the coils <NUM>, <NUM>, <NUM> (depicted schematically in <FIG>). In one embodiment, the detection system <NUM> comprises a faraday shield, generally indicated at <NUM>, configured to shield the receive coils <NUM>, <NUM> from external electrical fields. To this end, the faraday shield <NUM> comprises a first faraday arrangement <NUM> (see <FIG>), insulators <NUM> (see <FIG>), and a second faraday arrangement <NUM> (see <FIG>). As best shown in <FIG>, the first faraday arrangement <NUM> comprises a strip of material, such as copper or aluminum, which is "wrapped" around the outer surface <NUM> and the inner surface <NUM> of the coil support frame <NUM> in an overlapping arrangement between spaced-apart first ends 92A, 92B.

As best shown in <FIG>, insulators <NUM> are provided at each of the first ends 92A, 92B. The insulators <NUM>, which may be realized as one or more "wraps" of insulating tape, are provided to prevent electrical contact across the first ends 92A, 92B of the first faraday arrangement <NUM>, as well as to prevent contact between the first faraday arrangement <NUM> and the second faraday arrangement <NUM>.

As illustrated in <FIG>, the second faraday arrangement <NUM> similarly comprises a strip of material, such as copper or aluminum, which is "wrapped" around or otherwise encompasses the outer surface <NUM> and the inner surface <NUM> of the coil support frame <NUM> in an overlapping arrangement between spaced-apart second ends 96A, 96B. Here, the second faraday arrangement <NUM> is wrapped over the insulators <NUM> so as to encompass the first ends 92A, 92B of the first faraday arrangement <NUM> such that the entire coil support frame <NUM> (and, thus, all portions of each of the receive coils <NUM>, <NUM>) is "wrapped" or otherwise encompassed by either the first faraday arrangement <NUM> and/or the second faraday arrangement <NUM>.

While the faraday shield <NUM> described above and illustrated in <FIG> is configured to encompass both of the receive coils <NUM>, <NUM>, it will be appreciated that each of the receive coils <NUM>, <NUM> could be provided with a respective faraday shield <NUM>, such as may be implemented where the coil support frame <NUM> is comprised of discrete components supporting the respective coils <NUM>, <NUM>, <NUM>, as noted above. Moreover, while the faraday arrangements <NUM>, <NUM> described herein each comprise "wrapped" strips of material such as copper or aluminum alloys, it will be appreciated that other materials, such as any suitable non-magnetic and electrically-conductive material, as well as different types or configurations of faraday arrangements <NUM>, <NUM> and/or insulators <NUM>, could be utilized for certain applications.

Referring now to <FIG>, in one embodiment, the detection system <NUM> comprises a field shaping arrangement, generally indicated at <NUM>, configured to shape magnetic fields generated by the transmit coil <NUM> during use, as is described in greater detail below, so as to direct, focus, or otherwise concentrate the magnetic field towards the passage <NUM> of the coil support frame <NUM> and away from the outside environment. To this end, the field shaping arrangement <NUM> comprises a strip of magnetic field shaping material <NUM> and a strip of insulating material <NUM>, which are "wrapped" around or otherwise encompasses the outer surface <NUM> of the coil support frame <NUM>. Here, the field shaping arrangement <NUM> is operatively attached to the coil support frame <NUM> so as to remain in a fixed position and orientation relative to the coils <NUM>, <NUM>, <NUM> during use. Here, too, the rigidity of the coil support frame <NUM> and the isolation from external forces afforded by the isolation mechanism <NUM> contribute to preventing deflection or relative movement of the field shaping arrangement <NUM> relative to the coils <NUM>, <NUM>, <NUM> during use. In the representative embodiment illustrated herein, three "loops" of each of the materials <NUM>, <NUM> are provided adjacent to the transmit coil <NUM> and relative to the receive coils <NUM>, <NUM>. As shown in <FIG>, the field shaping arrangement <NUM> is disposed vertically between the receive coils <NUM>, <NUM>. However, other configurations and arrangements could be used. The insulating material <NUM> is provided to prevent physical contact between the "loops" of the magnetic field shaping material <NUM>. While three "loops" of each of the materials <NUM>, <NUM> are shown in the representative embodiment depicted in <FIG>, those having ordinary skill in the art will appreciate that more or fewer "loops" could be employed, depending on application requirements and the specific configuration of the field shaping arrangement <NUM>, such at the size, shape, and/or magnetic permeability of the magnetic field shaping material <NUM>.

The magnetic field shaping material <NUM> is configured, shaped, and arranged so as to direct, focus, or otherwise concentrate the magnetic field towards the passage <NUM> of the coil support frame <NUM>, as noted above. To this end, the magnetic field shaping material <NUM> may be comprised of a suitable material such as CarTech® High Permeability "<NUM>"® Alloy which, when treated, forms an oxide layer which may serve as the insulating material <NUM> noted above. However, those having ordinary skill in the art will appreciate that the field shaping arrangement <NUM> could be configured in a number of different ways and could comprise any suitable type of magnetic field shaping material <NUM> and/or insulating material <NUM>.

As is described in greater detail below, the waveform <NUM> has a baseline <NUM> condition corresponding to absence of interaction of metallic objects within the magnetic field generated by the transmit coil <NUM>. Here, because the waveform <NUM> can be generated by the controller <NUM> in a number of different ways, those having ordinary skill in the art will appreciate that the baseline <NUM> can similarly be defined in different ways. By way of non-limiting example, the baseline <NUM> could represent zero voltage and the waveform <NUM> could change in amplitude from the baseline <NUM> between various positive and negative voltages over time. Thus, it will be appreciated that the baseline <NUM> can be defined in any suitable way, and the waveform <NUM> can be generated based on any suitable parameter which changes with respect to the baseline <NUM> where the baseline <NUM> is established when there is no metal interacting with the magnetic field generated by the transmit coil <NUM>, in any suitable domain sufficient to detect the passage of metallic objects into the opening <NUM> of the medical waste container <NUM>, as noted above. In one embodiment, the waveform <NUM> baseline <NUM> could include a DC offset voltage greater than zero.

Referring now to <FIG>, various graphs are depicted. Here, for the purposes of clarity and consistency, unless otherwise indicated, each of these graphs are plotted horizontally with respect to time and vertically with respect to a voltage which is offset from zero. As such, in the description which follows, phrases such as "increasing amplitude" indicate a voltage moving away from zero over time in a positive direction (for example, from 1v to <NUM>. 5v), while phrases such as "decreasing amplitude" indicate a voltage moving towards zero over time in a negative direction (for example, <NUM>. It will be appreciated that this nomenclature is used herein for the non-limiting purposes of clarity and consistency.

Referring now to <FIG>, a set of graphs are shown along a common time scale delineated between seven equally-spaced time references T1A, T2A, T3A, T4A, T5A, T6A, and T7A. Here, the graphs respectively represent the transmit signal <NUM> in the transmit coil <NUM> (see <FIG>), the first receive signal <NUM> in the first receive coil <NUM> (see <FIG>), the second receive signal <NUM> in the second receive coil <NUM> (see <FIG>), and the waveform <NUM> generated by the controller <NUM> based on the receive signals <NUM>, <NUM> (see <FIG>) during an operating condition of the detection system <NUM>. The baseline <NUM> condition of the waveform <NUM> corresponds to absence of interaction of metallic objects with the magnetic field, as noted above. Here, the transmit signal <NUM> is a sinusoidal oscillating voltage and the magnetic field is an alternating magnetic field. As will be appreciated from the subsequent description below, this sinusoidal transmit signal <NUM> can be operated at different power levels, voltages, and frequencies depending on characteristics such as the size of the opening <NUM>, the size and type of metallic items targeted for detection and size, the type of the power source <NUM> used to operate the system, and the like. In one embodiment, the transmit signal operating frequency is between <NUM> and <NUM>. In one embodiment, the transmit signal operating frequency is between <NUM> and <NUM>. In another embodiment, the transmit signal operating frequency is less than or equal to <NUM>. In one embodiment, the transmit signal operating frequency is <NUM> for a battery operated system.

The first receive signal <NUM> shown in <FIG> and the second receive signal <NUM> shown in <FIG> are equal and opposite to each other from the first time reference T1A to the seventh time reference T7A (compare amplitude, frequency, and phase shown in <FIG>). Thus, because no imbalance occurs between the receive signals <NUM>, <NUM>, the resulting waveform <NUM> generated by the controller <NUM> is shown as a substantially flat line from the first time reference T1A to the seventh time reference T7A so as to indicate that the baseline <NUM> remains substantially constant over time (see <FIG>). Put differently, the baseline <NUM> has zero amplitude (no AC component) during this operating condition. Here, the receive signals <NUM>, <NUM> are summed to create the resulting waveform <NUM>. More specifically, because of the electrical balancing and physical symmetry of the coils <NUM>, <NUM>, <NUM> and the absence of interaction of metallic objects with the magnetic field, no imbalance occurs between the first receive signal <NUM> and the second receive signal <NUM> here and, thus, the waveform <NUM> remains at the baseline <NUM> from first time reference T1A to the seventh time reference T7A.

Referring now to <FIG>, another set of graphs are shown along a different common time scale delineated between seven equally-spaced time references T1B, T2B, T3B, T4B, T5B, T6B, and T7B. Here, the graphs respectively represent the first receive signal <NUM> in the first receive coil <NUM> (see <FIG>), the second receive signal <NUM> in the second receive coil <NUM> (see <FIG>), and the waveform <NUM> generated by the controller <NUM> based on the receive signals <NUM>, <NUM> (see <FIG>) during an operating condition of the detection system <NUM> wherein the waveform <NUM> has a baseline <NUM> condition corresponding to a transient interaction of a metallic object with the magnetic field which affects both receive signals <NUM>, <NUM> simultaneously.

The transient metallic object described above and represented in the graphs depicted in <FIG> could be a portable steel IV pole used to hang fluid bags (not shown, but generally known in the art). Here, the IV pole is placed nearby the detection system <NUM>, but outside a footprint of the mobile cart <NUM>, at the third time reference T3B and, thus, begins to affect the amplitude of the receive signals <NUM>, <NUM> simultaneously at the third time reference T3B (compare amplitude in <FIG>). However, because the steel IV pole affects the receive signals <NUM>, <NUM> simultaneously and equally, no differential occurs between the receive signals <NUM>, <NUM> and, thus, the resulting waveform <NUM> generated by the controller <NUM> is shown as a substantially flat line from the first time reference T1B to the seventh time reference T7B so as to indicate that the baseline <NUM> remains substantially constant over time (see <FIG>). Put differently, the baseline <NUM> has zero amplitude (no AC component) during this operating condition. Thus, simultaneous changes occurring in the receive signals <NUM>, <NUM> are not noticed in the waveform <NUM> when combined by the controller <NUM>, thereby contributing to enhanced sensitivity and helping to prevent inadvertent and inaccurate activation of the detection indicator <NUM> in response to transient metallic objects passing nearby the detection system <NUM>.

Referring now to <FIG>, another set of graphs are shown along a different common time scale delineated between seven equally-spaced time references T1C, T2C, T3C, T4C, T5C, T6C, and T7C. Here, the graphs respectively represent the first receive signal <NUM> in the first receive coil <NUM> (see <FIG>), the second receive signal <NUM> in the second receive coil <NUM> (see <FIG>), and the waveform <NUM> generated by the controller <NUM> based on the receive signals <NUM>, <NUM> (see <FIG>) during an operating condition of the detection system <NUM> wherein a metallic object passes through the opening <NUM> of the medical waste container <NUM>. As shown in <FIG>, in one embodiment, the receive signals <NUM>, <NUM> are combined arithmetically into a single combined signal, generally indicated at <NUM>, resulting from the absolute value of the second receive signal <NUM> subtracted from the absolute value of the first receive signal <NUM>. Here, the controller <NUM> can generate the waveform <NUM> shown in <FIG> by enveloping the combined signal <NUM>. It will be appreciated that enveloping of the combined signal <NUM> can be effected in a number of different ways, such as with rectifiers, inverters, and/or other circuits or modules. More specifically, the waveform <NUM> can be generated using any suitable type of integrating circuit sufficient to determine the area under the time domain curve of the combined signal <NUM>.

The metallic object described above and represented in the graphs depicted in <FIG> could be a reusable surgical tool manufactured from stainless steel (not shown, but generally known in the art). Here, the surgical tool passes consecutively through the first receive coil <NUM>, the transmit coil <NUM>, and then the second receive coil <NUM>. In this representative embodiment, the surgical tool begins to affect the amplitude of the first receive signal <NUM> between the second time reference T2C and the third time reference T3C as the surgical tool approaches the first receive coil <NUM>, and subsequently begins to affect the amplitude of the second receive signal <NUM> between the fourth time reference T4C and the fifth time reference T5C as the surgical tool approaches the second receive coil <NUM>, having passed through the first receive coil <NUM> and the transmit coil <NUM>. Thus, the first receive signal <NUM> changes before the second receive signal <NUM> changes (compare <FIG>), which causes the resulting waveform <NUM> to move from the baseline <NUM> in response. Specifically, as shown in <FIG>, the waveform <NUM> begins to move from the baseline <NUM> after the second time reference T2C and increases in amplitude from the baseline <NUM> as the surgical tool approaches the first receive coil <NUM>, and subsequently decreases in amplitude back towards the baseline <NUM> after the surgical tool passes through the first receive coil <NUM> and approaches the transmit coil <NUM>.

As shown in <FIG>, the waveform <NUM> continues to decrease in amplitude as the surgical tool passes through the transmit coil <NUM> and approaches the second receive coil <NUM>. The waveform <NUM> subsequently increases in amplitude back towards the baseline <NUM> after the surgical tool passes through the second receive coil <NUM>. It will be appreciated that additional information about the surgical tool's interaction with the metal detection system can be determined. For example, the time when the surgical tool interacts equally with both receive signals <NUM>, <NUM> is when the combined signal <NUM> intersects the baseline <NUM> at time T9. This typically would be very close to the time when the object is at the center plane formed by the transmit coil <NUM>. In addition, the time it takes the object to travel through the magnetic field would be when the combined signal <NUM> first deviates from its baseline at time T8, passing the midpoint at time T9 and then leaving the magnetic field at time point T10. In some embodiments, various times related to the combined signal <NUM> or the waveform <NUM> can be analyzed in order to improve the determination of detection events, count detection events or set detection indicator <NUM>.

The controller <NUM> analyzes the waveform <NUM> with respect to a first detection threshold <NUM> and also to a second detection threshold <NUM> opposite to the first detection threshold <NUM>, with the baseline <NUM> being between the first detection threshold <NUM> and the second detection threshold <NUM>. Here, the controller <NUM> is configured to activate the detection indicator <NUM> in response to the metal surgical tool passing through the coils <NUM>, <NUM>, <NUM>, based on the waveform <NUM> exceeding the first detection threshold <NUM> at a first time <NUM> and exceeding the second detection threshold <NUM> at a subsequent second time <NUM>.

During an absence of interaction of metallic objects with the magnetic field, as shown in <FIG>, the receive signals <NUM>, <NUM> result directly from the transmit signal <NUM>, and are substantially equal and opposite to each other because of the electrical balancing and physical symmetry of the coils <NUM>, <NUM>, <NUM> of the detection system <NUM>, as noted above. More specifically, flux from the magnetic field is advantageously distributed evenly between the receive coils <NUM>, <NUM> and, thus, the receive signals <NUM>, <NUM> are substantially equal and opposite to each other when there are no magnetic objects interacting with the magnetic field generated by the transmit coil <NUM>. However, when a differential occurs between the receive signals <NUM>, <NUM>, the waveform <NUM> correspondingly moves from the baseline <NUM>, as shown, in one example, in <FIG>. Thus, interaction of metallic objects with the magnetic field generated by the transmit coil <NUM> is reflected in the receive signals <NUM>, <NUM>. Here, the controller <NUM> analyzes movement of the waveform <NUM> from the baseline <NUM> and with respect to the detection thresholds <NUM>, <NUM> to detect passage of metallic objects through the opening <NUM> of the medical waste container <NUM>.

It will be appreciated that objects can interact with the magnetic field generated by the transmit coil <NUM> in a number of different ways. In particular, material properties and physical characteristics of the object affect how the receive signals <NUM>, <NUM> change in response to interaction with the magnetic field. As such, objects of different sizes, shapes, and material compositions passing through the coils <NUM>, <NUM>, <NUM> can affect movement of the waveform <NUM> from the baseline <NUM> in correspondingly different ways.

By way of example, if a non-conductive and magnetic material (ferromagnetic or paramagnetic), such as a ferrite tile, interacts with the magnetic field generated by the transmit coil <NUM>, the distribution of magnetic flux from the transmit coil <NUM> and around the receive coils <NUM>, <NUM> will be altered because of a change in the total permeability in the volume adjacent the coils <NUM>, <NUM>, <NUM>. Similarly, if a conductive and magnetic material (ferromagnetic, paramagnetic, or diamagnetic), such as a metal needle, interacts with the magnetic field generated by the transmit coil <NUM>, eddy current will be induced in the object which, in turn, creates a secondary magnetic field in opposition to the magnetic field generated by the transmit coil <NUM>.

It will be appreciated that the specific configuration of the secondary magnetic field generated as a result of eddy currents depends on physical characteristics of the conductive magnetic object, such as conductivity, permeability, size, shape, and orientation. Conductive materials with high relative permeability (for example: steel) will tend to increase the total permeability in the volume adjacent the coils <NUM>, <NUM>, <NUM> because the secondary magnetic field created by eddy currents within the material is generally insufficient to counteract the magnetic field generated by the transmit coil <NUM>. However, highly-conductive materials with low relative permeability (for example: copper or aluminum) will tend to decrease the total permeability in the volume adjacent the coils <NUM>, <NUM>, <NUM> because the secondary magnetic field created by eddy currents within the highly-conductive material tends to repel the magnetic field generated by the transmit coil <NUM>. Further, moderately-conductive materials that have low relative permeability (for example: tin, lead, titanium, and certain types of stainless steel) will have a relatively small effect on the total permeability in the volume adjacent the coils <NUM>, <NUM>, <NUM> because the secondary magnetic field results from relatively small eddy currents within the moderately-conductive material.

In the representative operating condition described above, the passage of the stainless steel surgical tool through the coils <NUM>, <NUM>, <NUM> causes a successive change in the amplitude of the receive signals <NUM>, <NUM> which, in turn, causes the waveform <NUM> to move from the baseline <NUM>. Here, while the amplitude of each of the receive signals <NUM>, <NUM> is reduced when the steel surgical tool approaches the respective receive coil <NUM>, <NUM>, those having ordinary skill in the art will appreciate that differential imbalance between the receive signals <NUM>, <NUM> can occur in other ways sufficient to move the waveform <NUM> from the baseline <NUM>. By way of a non-limiting example, the receive signals <NUM>, <NUM> could successively increase in amplitude, increase or decrease in frequency, and/or shift in phase in response to certain metallic objects passing through the coils <NUM>, <NUM>.

As such, it will be appreciated that the waveform <NUM> generated by the controller <NUM> could move from the baseline <NUM> in response to any suitable predetermined type of differential change occurring between the receive signals <NUM>, <NUM>. Moreover, it will be appreciated that different types of materials effect correspondingly different differential changes in the receive signals <NUM>, <NUM> when interacting with the magnetic field generated by the transmit coil <NUM>, based on size, shape, conductivity, permeability, and the like, as noted above. Thus, the detection system <NUM> could be configured so as to recognize certain materials or objects based at least partially upon characteristic differential changes occurring in the amplitude, frequency, and/or phase of the receive signals <NUM>, <NUM> and/or the waveform <NUM>. As such, the controller <NUM> could further be configured to operate differently depending on the particular object recognized. By way of a non-limiting example, the controller <NUM> could be configured so as not to activate the detection indicator <NUM>, or to activate the detection indicator <NUM> in a different way (such as with a distinct audible tone or light activation/flash rate) when certain recognized metallic objects pass through the coils <NUM>, <NUM>, <NUM>, such as a commonly discarded metallic objects (for example: a foil wrapper, grounding pad, an instrumentation tip, or a sensor cable).

Referring now to <FIG>, an alternate and enlarged version of the graph depicted in <FIG> is shown with additional detail. The graph shown in <FIG> is likewise shown along a time scale delineated between seven equally-spaced time references T1C, T2C, T3C, T4C, T5C, T6C, and T7C. Here too, the graph represents the waveform <NUM> generated by the controller <NUM> based on the receive signals <NUM>, <NUM> during an operating condition of the detection system <NUM> when a metallic object, such as the stainless steel surgical tool, passes into the opening <NUM> of the medical waste container <NUM>. In this operating condition of the detection system <NUM>, the waveform <NUM> exceeds the first detection threshold <NUM> at the first time <NUM>, and subsequently exceeds the second detection threshold <NUM> at the second time <NUM>.

In one embodiment, the controller <NUM> comprises an analyzation circuit <NUM> (see <FIG>) which is configured to monitor the waveform <NUM> with respect to the baseline <NUM> and the detection thresholds <NUM>, <NUM> so as to detect the passage of metallic objects into the opening <NUM> of the medical waste container <NUM>. In one embodiment, the analyzation circuit <NUM> (see <FIG>) of the controller <NUM> is configured to activate the detection indicator <NUM> in response to the waveform <NUM> exceeding the first detection threshold <NUM> at the first time <NUM>, and exceeding the second detection threshold <NUM> at the second time <NUM>. In one embodiment, the analyzation circuit <NUM> (see <FIG>) of the controller <NUM> is configured to activate the detection indicator <NUM> in response to the waveform <NUM> being between the detection thresholds <NUM>, <NUM> at a subsequent third time <NUM>.

As will be appreciated from the subsequent description below, the detection thresholds <NUM>, <NUM> could be defined in any suitable way and with any suitable orientation with respect to each other sufficient to enable the controller <NUM> to detect movement of the waveform <NUM> successively across each of the detection thresholds <NUM>, <NUM>. By way of non-limiting example, the waveform <NUM> depicted in <FIG> could represent a steel object passing through the coils <NUM>, <NUM>, <NUM> into the opening <NUM> of the medical waste container <NUM>. Here, the second detection threshold <NUM> is equal in terms of amplitude to the first detection threshold <NUM>, and is defined as being "below" the first detection threshold <NUM> and the baseline <NUM> of the waveform <NUM>. Conversely, the waveform <NUM> depicted in <FIG> could represent an aluminum object passing through the coils <NUM>, <NUM>, <NUM> into the opening <NUM> of the medical waste container <NUM>. Here, the second detection threshold <NUM> is equal in terms of amplitude to the first detection threshold <NUM>, but is defined as being "above" the first detection threshold <NUM> and the baseline <NUM> of the waveform <NUM>. Thus, the detection thresholds <NUM>, <NUM> can be defined in any suitable way with respect to each other with the waveform <NUM> exceeding the first detection threshold <NUM> before the second detection threshold <NUM> when a metallic object passes into the opening <NUM> of the medical waste container <NUM>.

As noted above, the operating condition of the detection system <NUM> depicted in <FIG> represents a stainless steel object passing into the opening <NUM> of the medical waste container <NUM>, wherein the waveform <NUM> moves towards the first detection threshold <NUM> with increasing amplitude as the stainless steel object approaches the first coil <NUM>. Here, the controller <NUM> is configured to activate the detection indicator <NUM> based on the waveform <NUM> successively: increasing amplitude over a first period <NUM> from the baseline <NUM> to beyond the first detection threshold <NUM> to define a first detection event point <NUM>; decreasing amplitude over a second period <NUM> from the first detection event point <NUM> to the baseline <NUM>; and decreasing amplitude over a third period <NUM> from the baseline <NUM> to beyond the second detection threshold <NUM> to define a second detection event point <NUM>. In one embodiment, the first and second periods <NUM>, <NUM> are of substantially equal duration. In other embodiments, the first and second periods <NUM>, <NUM> are different durations. These first and second periods <NUM>, <NUM> are proportional to the amount of time a metallic item first enters the magnetic field until it reaches a center plane defined by the transmit coil <NUM>.

In another embodiment, the analyzation circuit <NUM> of the controller <NUM> is configured to activate the detection indicator <NUM> based on the waveform <NUM> increasing amplitude over a fourth period <NUM> from the second detection event point <NUM> to the baseline <NUM> Here, because a predetermined amount of time must elapse before the waveform <NUM> will settle to the baseline <NUM>, the analyzation circuit <NUM> of the controller <NUM> may alternatively be configured to activate the detection indicator <NUM> based on the waveform <NUM> increasing amplitude over the fourth period <NUM> from the second detection event point <NUM> to within a predetermined threshold with respect to the baseline <NUM>, such as within <NUM>% of the amplitude of the waveform <NUM> occurring at the second detection event point <NUM>. In one embodiment, the analyzation circuit <NUM> (see <FIG>) of the controller <NUM> is configured to activate the detection indicator <NUM> in response to the waveform <NUM> exceeding the first detection threshold <NUM> and the second detection threshold <NUM> at the second time <NUM>. It will be appreciated that the controller <NUM> can activate the detection indicator <NUM> based on the thresholds <NUM>, <NUM> and irrespective of the periods described above.

Once the first detection threshold <NUM> is exceeded at the first time <NUM>, the controller <NUM> marks the beginning of a detection event. Once the first detection event point <NUM> is reached, an actual detection event will cause the waveform <NUM> to pass back through the baseline <NUM> to the second detection event point <NUM> after the second threshold <NUM> is exceeded at the second time <NUM>, as noted above. The amplitude of the waveform <NUM> at the second detection event point <NUM> should be at least <NUM>% of the second threshold <NUM>, as well as at least <NUM>% of the opposing amplitude occurring at the first detection event point <NUM>. Here, if the amplitude of the waveform <NUM> does not exceed the second threshold <NUM> at the second time <NUM>, then no detection event occurs because the metallic object did not pass through both of the receive coils <NUM>, <NUM>. Similarly, if the amplitude of the waveform <NUM> exceeds the second threshold <NUM> at the second time <NUM>, but the amplitude occurring at the second detection event point <NUM> is less than <NUM>% of the opposing amplitude occurring at the first detection event point <NUM>, then no detection event occurs because the metallic object did not pass through both of the receive coils <NUM>, <NUM>.

As noted above, the operating condition of the detection system <NUM> depicted in <FIG> represents an aluminum object passing into the opening <NUM> of the medical waste container <NUM>, wherein the waveform <NUM> moves towards the first detection threshold <NUM> with decreasing amplitude as the aluminum object approaches the first coil <NUM>. Here, the controller <NUM> is configured to activate the detection indicator <NUM> based on the waveform <NUM> successively: decreasing amplitude over the first period <NUM> from the baseline <NUM> to beyond the first detection threshold <NUM> to define the first detection event point <NUM>; increasing amplitude over the second period <NUM> from the first detection event point <NUM> to the baseline <NUM>; and increasing amplitude over the third period <NUM> from the baseline <NUM> to beyond the second detection threshold <NUM> to define the second detection event point <NUM>. In one embodiment, the controller <NUM> is configured to activate the detection indicator <NUM> based on the waveform <NUM> decreasing amplitude over the fourth period <NUM> from the second detection event point <NUM> to the baseline <NUM>.

The detection system <NUM> is advantageously configured so as not to activate the detection indicator <NUM> when a metallic object is subsequently removed from the medical waste container <NUM>, which can be irritating to users. However, as noted above, different types of metallic objects passing into the opening <NUM> of the medical waste container <NUM> interact with the magnetic field generated by the transmit coil <NUM> in different ways. By way of non-limiting example, while the waveform <NUM> depicted in <FIG> represents a steel object passing into the medical waste container <NUM> and the waveform <NUM> depicted in <FIG> represents an aluminum object passing into the medical waste container <NUM>, the waveform <NUM> depicted in <FIG> could alternatively represent a steel object being removed from the medical waste container <NUM>. More specifically, movement of a steel object out of the medical waste container <NUM> could result in a waveform <NUM> which is similar to a waveform <NUM> generated as a result of an aluminum object moving into the medical waste container <NUM>.

In order to prevent activation of the detection indicator <NUM> during an operating condition where a metallic object is removed from the medical waste container <NUM>, in one embodiment, the analyzation circuit <NUM> of the controller <NUM> is configured to simultaneously analyze the receive signals <NUM>, <NUM> as well as the waveform <NUM> generated from the receive signals <NUM>, <NUM>. The controller <NUM> is configured to activate the detection indicator <NUM> based on predetermined changes occurring in the first receive signal <NUM> of the first receive coil <NUM> and subsequent predetermined changes occurring in the second receive signal <NUM> of the second receive coil <NUM>, and based further on the waveform <NUM> exceeding the first detection threshold <NUM> at the first time <NUM> and exceeding the second detection threshold <NUM> at the subsequent second time <NUM>. Thus, a change occurring in the second receive signal <NUM> before the first receive signal <NUM> represents removal of a metallic object irrespective of the specific physical configuration or material properties of the object, and the controller <NUM> will not activate the detection indicator <NUM> in response because the first receive coil <NUM> is spaced above the second receive coil <NUM> such that objects dropped into the opening <NUM> of the medical waste container <NUM> pass through the first receive coil <NUM> before passing through the second receive coil <NUM> (see <FIG>, <FIG>).

During certain operating conditions of the detection system <NUM>, transient metallic objects passing nearby the coils <NUM>, <NUM>, <NUM> can interact with the magnetic field generated by the transmit coil <NUM> such that the waveform <NUM> at least partially moves from the baseline <NUM> in response. Specifically, where transient metallic objects nearby the detection system <NUM> move unevenly with respect to the arrangement of the coils <NUM>, <NUM>, <NUM>, the resulting waveform <NUM> could move from the baseline <NUM> despite the filtering afforded by the electrical and physical balancing described above.

Referring now to <FIG>, graphs are shown depicting certain operating conditions of the detection system <NUM> where transient movement of a metallic object affects one of the receive signals <NUM>, <NUM> enough to move the waveform <NUM> from the baseline <NUM> without passing through the coils <NUM>, <NUM>, <NUM>. By way of non-limiting example, such a transient metallic object could be a wristwatch worn by a person walking nearby the mobile cart <NUM>. The waveform <NUM> depicted in <FIG> would be generated if the wristwatch were positioned vertically closer to the first receive coil <NUM> than to the second receive coil <NUM>. Here, the first receive signal <NUM> changes while the second receive signal <NUM> remains substantially unchanged. Similarly, the waveform <NUM> depicted in <FIG> would be generated if the wristwatch were positioned vertically closer to the second receive coil <NUM> than to the first receive coil <NUM>. Here, the second receive signal <NUM> changes while the first receive signal <NUM> remains substantially unchanged.

Thus, transient metallic objects passing at least partially horizontally nearby the receive coils <NUM>, <NUM> could cause a differential change between the receive signals <NUM>, <NUM> sufficient to move the waveform <NUM> from the baseline <NUM>. However, transient movement of this type does not result in a waveform <NUM> which is indicative of passage of a metallic object into the opening <NUM> of the medical waste container <NUM> because the waveform <NUM> will not successively exceed both of the detection thresholds <NUM>, <NUM>. Rather, the operating conditions described above will result in the analyzation circuit <NUM> of the controller <NUM> seeing only one of the detection thresholds <NUM>, <NUM> exceeded, after which the waveform <NUM> will subsequently return to the baseline <NUM> as the metallic object moves away from the magnetic field.

Referring now to <FIG> and <FIG>, as noted above, the controller <NUM> activates the detection indicator <NUM> in response to the first and second detection thresholds <NUM>, <NUM> being successively exceeded. In one embodiment, the detection thresholds <NUM>, <NUM> are adjustable by a user input control, shown generically at <NUM> (see also <FIG> and <FIG>). The user input control <NUM> is in electrical communication with the controller <NUM> and allows the user to manually adjust the sensitivity and/or operating mode of the detection system <NUM>, as described in greater detail below. By way of non-limiting example, the user input control <NUM> could be realized as a rotary potentiometer employed to at least partially change the detection thresholds <NUM>, <NUM> with respect to the baseline <NUM> of the waveform <NUM>. However, it will be appreciated that the user input control <NUM> could be realized in a number of different ways and, thus, could be configured to communicate with or otherwise control the detection system <NUM> in any suitable way sufficient to effect user-manipulated adjustability and/or control. For instance, the user input control <NUM> could be implemented as inputs on a touch screen, physical buttons that activate switches, and the like. Moreover, it will be appreciated that the user input control <NUM> could serve other purposes, such as to silence the detection indicator <NUM>.

In one embodiment, the controller <NUM> includes a noise calculator <NUM> configured to establish first and second noise boundaries <NUM>, <NUM> based on prior minimum and maximum values of the waveform <NUM> received over a predetermined period of time (see <FIG>). The noise calculator <NUM> is employed to help determine the detection thresholds <NUM>, <NUM> based at least partially on the set noise boundaries <NUM>, <NUM>, whereby subsequent movement of the waveform <NUM> from the baseline <NUM> that does not exceed the noise boundaries <NUM>, <NUM> can be ignored or otherwise filtered out. Thus, changes in the waveform <NUM> below the noise boundaries <NUM>, <NUM> can be considered noise, and certain changes in the waveform <NUM> above the noise boundaries <NUM>, <NUM> can be used to determine the presence of metallic objects passing into the opening <NUM> of the medical waste container <NUM>.

Here, the detection thresholds <NUM>, <NUM> are established as a percentage of the noise boundaries <NUM>, <NUM> greater than <NUM>%. In one embodiment, the detection thresholds <NUM>, <NUM> are established as <NUM>% of the noise boundaries <NUM>, <NUM>. In another embodiment, the detection thresholds <NUM>, <NUM> are established as <NUM>% of the noise boundaries <NUM>, <NUM>. In another embodiment, the detection thresholds <NUM>, <NUM> are established as <NUM>% of the noise boundaries <NUM>, <NUM>. However, it will be appreciated that the detection thresholds <NUM>, <NUM> can be set with respect to the noise boundaries <NUM>, <NUM> in different ways, depending on the application and the operating environment in which the detection system <NUM> is utilized. Moreover, it will be appreciated that detection thresholds <NUM>, <NUM> that are set as values approaching the noise boundaries <NUM>, <NUM> can improve detection sensitivity and, thus, improve the detection system's <NUM> ability to detect metallic objects with relatively small magnetic field signatures.

Those having ordinary skill in the art will appreciate that the sensitivity of the detection system <NUM> is higher when the detection thresholds <NUM>, <NUM> are set closer to the noise boundaries <NUM>, <NUM>. Moreover, it will be appreciated that the detection system <NUM> can be configured to adjust the noise boundaries <NUM>, <NUM> over time to compensate for environmental changes occurring during use. Thus, in addition to initially setting the noise boundaries <NUM>, <NUM> and the detection thresholds <NUM>, <NUM>, it is also advantageous to recalibrate the detection system <NUM> under certain operating conditions. To that end, in one embodiment, the analyzation circuit <NUM> of the controller <NUM> employs a calibration circuit <NUM>. The calibration circuit <NUM> cooperates with a compensation circuit <NUM> and a gain amplification circuit <NUM> to monitor the waveform <NUM> over time for predetermined changes that indicate a need for recalibration so as to ensure detection accuracy.

As previously discussed, the detection system <NUM> is advantageously electrically balanced so as to effect enhanced sensitivity and detection accuracy. To that end, the controller <NUM> is employed to effect electrical balance of the coils <NUM>, <NUM>, <NUM>. In one embodiment, the compensation circuit <NUM> is disposed in electrical communication with the first receive coil <NUM> and the second receive coil <NUM>, and is configured to inductively balance the receive signals <NUM>, <NUM> so as to minimize the baseline <NUM> of the waveform <NUM> such that subsequent changes from the baseline <NUM> can be accurately analyzed. Here, the compensation circuit <NUM> enhances the sensitivity of the detection system <NUM> by balancing the first receive signal <NUM> with the second receive signal <NUM> in terms of amplitude, frequency, and phase during an operating condition of the detection system <NUM> where no metallic objects interact with the magnetic field generated by the transmit coil <NUM>. To that end, the compensation circuit <NUM> could utilize one or more microprocessors/microcontrollers configured to balance the receive signals <NUM>, <NUM> when the detection system <NUM> is initialized, or as required during operation (not shown). As such, it will be appreciated that that enhanced sensitivity is promoted where the detection system <NUM> utilizes as little metallic material, components, structure, and the like as is practical. However, it will be appreciated that a certain amount of the detection system <NUM> necessarily involves the use of internal metallic components (such as the coils) to effect detection.

In one embodiment, the controller <NUM> employs a combination circuit <NUM> to combine the balanced receive signals <NUM>, <NUM> into the waveform <NUM>. To that end, in one embodiment, the combination circuit <NUM> is realized as a differential amplifier configured to combine the receive signals <NUM>, <NUM> into the waveform <NUM> and further configured to attenuate the waveform <NUM> to the baseline <NUM> with zero amplitude. The controller <NUM> employs the gain amplification circuit <NUM> to amplify the waveform <NUM>. Here, the gain amplification circuit <NUM> increases the sensitivity of the detection system <NUM> by amplifying the waveform <NUM> generated from the combined, balanced receive signals <NUM>, <NUM> such that subsequent movement of the waveform <NUM> from the baseline <NUM> reflects imbalance between the receive signals <NUM>, <NUM> caused by interaction of metallic objects with the magnetic field generated by the transmit coil <NUM>.

With reference now to the logic maps illustrated in <FIG>, <FIG> and <FIG>, various logic steps employed by the detection system <NUM> are shown generally. Here, for the purposes of clarity and consistency, the steps are identified only with respect to the numeral with which they are introduced, beginning with numeral <NUM>.

The detection system <NUM> is advantageously initialized in step <NUM> when there are no magnetic objects interacting with the magnetic field generated by the transmit coil <NUM>. After initialization in step <NUM>, the compensation circuit <NUM> balances the receive signals <NUM>, <NUM> in step <NUM> and the noise calculator <NUM> establishes the noise boundaries <NUM>, <NUM> based on the waveform <NUM> in step <NUM>. Next, the detection thresholds <NUM>, <NUM> are established in step <NUM> based on the noise boundaries <NUM>, <NUM>. Here, in step <NUM>, the detection thresholds <NUM>, <NUM> can also be manipulated by the user, such as via the user input control <NUM>, as described above. Once the detection thresholds <NUM>, <NUM> are established, the controller <NUM> then monitors the waveform <NUM> in step <NUM> for changes with respect to the baseline <NUM>. Specifically, the analyzation circuit <NUM> of the controller <NUM> monitors the waveform <NUM> in step <NUM> for movement from the baseline <NUM> which exceeds the detection thresholds <NUM>, <NUM>, occurring in step <NUM>. The controller <NUM> also simultaneously monitors for recalibration in step <NUM>, which can be prompted automatically by the calibration circuit <NUM> or can be prompted manually by the user, such as via the user input control <NUM>. If recalibration is prompted, in one embodiment, the controller <NUM> then re-balances the receive signals <NUM>, <NUM> by returning to step <NUM>, and re-establishes the noise boundaries <NUM>, <NUM> in step <NUM> and the detection thresholds <NUM>, <NUM> in step <NUM> before subsequently continuing to monitor the waveform <NUM> in step <NUM>.

With continued reference to <FIG> and <FIG>, once the analyzation circuit <NUM> of the controller <NUM> determines that the detection thresholds <NUM>, <NUM> have been exceed in step <NUM>, the controller <NUM> subsequently activates the detection indicator <NUM> in step <NUM>. In the embodiment illustrated in <FIG>, the analyzation circuit <NUM> of the controller <NUM> also checks in step <NUM> to make sure the first receive signal <NUM> changed before the second receive signal <NUM> so as to differentiate between a metallic object being placed into the opening <NUM> of the medical waste container <NUM>, and a metallic object being removed from the medical waste container <NUM>.

As noted above, the detection indicator <NUM> could be implemented as an audible alarm and/or a visual alarm. By way of example, the detection indicator <NUM> could sound an audible alarm in step <NUM> whenever a metallic object passes into the opening <NUM> of the medical waste container <NUM> as determined in step <NUM>, and the controller <NUM> could return to step <NUM> to continue to monitor the waveform <NUM> and re-sound the alarm in step <NUM> in response to a subsequent detection event determined in step <NUM>.

Similarly, the detection indicator <NUM> could flash a light source in step <NUM> when a metallic object passes into the opening <NUM> of the medical waste container <NUM> as determined in step <NUM>, and the controller <NUM> could return to step <NUM> to continue to monitor the waveform <NUM> in step <NUM> and re-illuminate the light source in step <NUM> in response to a subsequent detection event determined in step <NUM>. Further, the detection indicator <NUM> could remain activated until deactivation is prompted in step <NUM> automatically by the controller <NUM> or prompted manually by the user, such as via the user input control <NUM>, after which the detection indicator <NUM> could be deactivated in step <NUM>. By way of example, the controller <NUM> could be configured to sound an alarm in step <NUM> via the detection indicator <NUM> until the metallic object is subsequently removed or until the user manipulates the user input control <NUM>, in step <NUM>.

The light source could be any light source suitable for indicating information to the user, such as a plurality of light emitting diodes, a plurality of multi-colored light emitting diodes, and the like. Additionally, the light source may be configured to generate visible light of different colors based on different information being conveyed to the user, such as red to indicate a detection event and green to indicate the absence of a detection event, but to show a ready status of the detection system <NUM>. Moreover, the detection indicator <NUM> could employ light sources to indicate progress of a detection event as it occurs, such as by successively illuminating different light sources such as when the thresholds <NUM>, <NUM> are exceeded, the detection event points <NUM>, <NUM> are established, the times <NUM>, <NUM>, <NUM> occur, and the like. Moreover, the detection indicator <NUM> could include a counter to display the number of detection events which have occurred.

It will be appreciated that interaction of any metallic objects within the magnetic field generated by the transmit coil <NUM> may result in reduced sensitivity of the detection system <NUM> because the detection thresholds <NUM>, <NUM> are established based on the noise boundaries <NUM>, <NUM> of waveform <NUM>. As noted above, the noise boundaries <NUM>, <NUM> represent minimum and maximum values of deviation of waveform <NUM> from the baseline <NUM> over a set period of time. Moreover, any interaction of metallic objects with the magnetic field can cause the waveform <NUM> to move from the baseline <NUM>, as described above. This movement causes the noise boundaries <NUM>, <NUM> to increase which, in turn, causes a corresponding increase in the detection thresholds <NUM>, <NUM> and, thus, a decrease in sensitivity. As such, it is advantageous for the control system <NUM> to compensate for decreased sensitivity caused by transient objects interacting with the magnetic field generated by the transmit coil <NUM>, as well as movement of the waveform <NUM> caused by metallic objects passing through the coils <NUM>, <NUM>, <NUM>. To that end, the calibration circuit <NUM> is configured to determine when to recalibrate. The time for recalibration may be based on as a predetermined amount of time passing, a detection event occurring, or a predetermined variation occurring in the waveform <NUM>. It will be appreciated that recalibration can be effected in a number of different ways, such as by re-balancing the receive signals <NUM>, <NUM>, and/or by re-establishing the noise boundaries <NUM>, <NUM> and/or the detection thresholds <NUM>, <NUM> for an operating state.

As such, it will be appreciated that the detection system <NUM> could employ a number of different strategies to determine when to effect recalibration. By way of non-limiting example, a logic map depicting one embodiment of such a strategy is illustrated in <FIG>. Here, the detection system <NUM> includes a do-not-use indicator <NUM> that is activated in step <NUM> whenever calibration or recalibration occurs in step <NUM>, until the do-not-use indicator <NUM> is deactivated in step <NUM>. It will be appreciated that activation of the do-not-use indicator <NUM> helps promote effective calibration due to user awareness, whereby the user can subsequently recalibrate via the user input control <NUM> if, for example, the user observes a metallic object being brought into close proximity with the detection system <NUM> while the do-not-use indicator <NUM> is activated. However, it will be appreciated that the do-not-use indicator <NUM> could be implemented in the detection system <NUM> in other ways, or could be omitted entirely.

With continued reference to <FIG>, the controller <NUM> monitors the waveform <NUM> in step <NUM> with respect to the baseline <NUM> established during calibration, and determines if the first detection threshold <NUM> has been exceeded in step 210A. If the first detection threshold <NUM> is exceeded, the controller <NUM> determines if the first detection threshold <NUM> is exceeded for less than a predetermined amount of time in step 210B, such as <NUM> seconds, then the controller <NUM> subsequently checks in step 210C to see if the second detection threshold <NUM> has been exceeded to indicate a detection event, as described in greater detail above in connection to <FIG> and <FIG>. However, in this embodiment, if the first detection threshold <NUM> has not been exceeded, or has been exceeded for less than the predetermined amount of time, then the controller <NUM> subsequently calculates a new baseline 104N and new noise boundaries 136N, 138N in step <NUM> so as to determine if and how recalibration should occur.

In step <NUM>, if the new noise boundaries 136N, 138N are larger than the previously established noise boundaries <NUM>, <NUM>, then the controller <NUM> compares the new noise boundaries 136N, 138N to the detection thresholds <NUM>, <NUM> established during calibration in step <NUM>. Here, if the new noise boundaries 136N, 138N are also larger than the detection thresholds <NUM>, <NUM>, then the controller <NUM> re-balances the receive signals <NUM>, <NUM> in step <NUM> and re-establishes the noise boundaries <NUM>, <NUM> in step <NUM> and the detection thresholds <NUM>, <NUM> in step <NUM> before continuing to monitor the waveform <NUM> in step <NUM>. However, if the new noise boundaries 136N, 138N are smaller than the detection thresholds <NUM>, <NUM> in step <NUM>, then the controller re-establishes the noise boundaries <NUM>, <NUM> in step <NUM> and the detection thresholds <NUM>, <NUM> in step <NUM> before continuing to monitor the waveform <NUM> in step <NUM>.

If, however, the new noise boundaries 136N, 138N are smaller than the previously established noise boundaries <NUM>, <NUM> in step <NUM>, and if the controller <NUM> determines that the new baseline 104N has shifted by <NUM>% or more in step <NUM> compared to the baseline <NUM> established previously during calibration, then the controller <NUM> re-balances the receive signals <NUM>, <NUM> in step <NUM> and re-establishes the noise boundaries <NUM>, <NUM> in step <NUM> and the detection thresholds <NUM>, <NUM> in step <NUM> before continuing to monitor the waveform <NUM> in step <NUM>. However, if the new baseline 104N has not shifted by <NUM>% or more in step <NUM>, then the controller <NUM> continues to monitor the waveform <NUM> in step <NUM>. It will be appreciated that any one of the steps described above could be performed by the controller <NUM> in any suitable order, including sequentially, non-sequentially, and/or simultaneously. Moreover, it will be appreciated that the controller <NUM> could implement different strategies which employ steps organized in any suitable way. In the above example, the shift of <NUM>% is provided as a non-limiting example wherein a different threshold of the shift percent can be used when appropriate.

As noted above, detection system <NUM> could be realized in a number of different ways and with a number of different configurations. Specifically, it will be appreciated that the controller <NUM>, compensation circuit <NUM>, combination circuit <NUM>, gain amplification circuit <NUM>, analyzation circuit <NUM>, calibration circuit <NUM>, and/or noise calculator <NUM> described above could be realized by any suitable number of discrete electrical components, modules, systems, sub-systems, processors, programs, and the like, that communicate or otherwise cooperate in any suitable way sufficient to effect detection of metallic objects passing through the coils <NUM>, <NUM>, <NUM>, as described above. Moreover, it will be appreciated that one or more of the circuits and/or functions of the controller <NUM> described above could be realized as or otherwise carried out by software running on a processor. By way of non-limiting example, the controller <NUM> could comprise a processor running a signal conditioning algorithm which performs the functions of the compensation circuit <NUM>, the combination circuit <NUM>, and the gain amplification circuit <NUM> described above. Here too, the controller <NUM> could employ a common processor to carry out the functions of the analyzation circuit <NUM>, as well as to generate the transmit signal <NUM>.

In this way, the detection system <NUM> provides significantly increased sensitivity in detecting metallic objects dropped into the opening <NUM> of the medical waste container <NUM> while, at the same time, affording enhanced detection accuracy. Specifically, it will be appreciated that the physical and electrical balancing of the receive coils <NUM>, <NUM> allows the controller <NUM> to monitor the waveform <NUM> for very slight variations from the baseline <NUM> while, at the same time, compensating for the presence of persistent and/or transient metallic objects positioned or moving nearby the detection system <NUM> and/or passing through the opening <NUM> of the medical waste container <NUM>. Moreover, it will be appreciated that the detection system <NUM> affords significant opportunities for enhanced detection system <NUM> functionality, such as the ability to recognize certain metallic objects passing through the coils <NUM>, <NUM>, <NUM> and, thus, to differentiate between inadvertently disposed metallic objects and commonly discarded metallic objects.

It will be further appreciated that the terms "include," "includes," and "including" have the same meaning as the terms "comprise," "comprises," and "comprising. " Moreover, it will be appreciated that terms such as "first,""second,""third," and the like are used herein to differentiate certain structural features and components for the non-limiting, illustrative purposes of clarity and consistency.

Claim 1:
A detection system for detecting disposal of metallic objects into an opening of a medical waste container (<NUM>), said detection system comprising:
a detection indicator (<NUM>) for indicating passage of metallic objects through the opening (<NUM>) of the medical waste container;
a pair of receive coils (<NUM>, <NUM>) and a transmit coil (<NUM>) spaced between said receive coils, the coils being shaped for receiving waste therethrough adjacent to the opening of the medical waste container;
a coil support frame (<NUM>) supporting each of said receive coils and said transmit coil;
a mount (<NUM>) for supporting said coil support frame;
a base (<NUM>) coupled to said mount for concurrent movement; and
an isolation mechanism (<NUM>) interposed between said mount and said coil support frame to isolate said coil support frame from external force acting on said mount.