Field of the Invention

The present invention relates to a waste cart capable of detecting metallic objects as they pass through the cart's openings is disclosed herein below.

Background of the Invention

The medical environment tends to generate three main forms of trash: sharps, biohazard materials, and ordinary trash. Hospital staff tends to waste money by negligently discarding equipment after surgery, typically by unintentionally depositing metal items (e.g., surgical tools) into the trash along with disposable garments (surgical "scrubs") and other potentially hazardous biological waste. The incorporation of a metal detector with a trash can helps to alleviate this problem.

Medical environments outside the hospital (e.g., doctors' offices, hospital rooms, and surgical suites) must also put proper protocols into place for the safe disposal of "sharps." Federal regulations (e.g., 49 CFR 173.134) define a "sharp" as any object that may be contaminated with a pathogen and that is capable of cutting or penetrating skin or a packaging material (and thus leading to injury or disease transmission or both). Sharps include items such as needles, scalpels, broken glass, culture dishes, etc.

Federal regulations (e.g., 49 CFR 173.197) require that sharps be placed in containers that are rigid, leak resistant, impervious to moisture, strong enough to prevent tearing or bursting during norma! conditions of transport, and puncture resistant.

US hospitals produce an estimated 8600 tons of waste daily and 4,000,000,000 pounds annually. Within the hospital, operating rooms tend to generate two main forms of trash; single use sterilized equipment and regular garbage which is sometimes needlessly bagged as hazardous waste. The well-recognized red bags are intended to be used for medical waste that requires more cautious-and thus more expensive- disposal procedures. Some research indicates, however, that up to 90% of items disposed in special red bags are simply regular trash that could be stored in a clear bag and disposed of more conveniently. Thus, a more efficient segregation and disposal of trash could provide significant cost savings in the healthcare industry.

Medical disposal and detector systems currently available have a number of shortcomings. In some, the openings are unfinished and expose the contents of a biohazard bag. The structural materials wear and lack the rigidity of conventional industrial disposals. Because a sterile environment is a fundamental hospital goal, certain types of plastics— especially inexpensive ones— do not necessarily reassure the user as to their cleanliness. Some plastics interact slightly with hospital cleaning materials and develop an undesired sticky texture. In some cases the structures are angular with protruding surfaces and corners, which in turn can catch on medical clothing and draping. Many structures are singular in their function, so that separate items are needed for the several types of expected waste, which in turn tends to crowd the medical space in an undesired, or in some cases an unsafe or unsanitary, manner.

Appropriate devices must also meet medical regulations for safely storing biohazard materials. The Bloodborne Pathogens Standard of the US Occupational Safety and Health Administration (OSHA) uses the term, "regulated waste," to refer to waste items such as:

• liquid or semi-liquid blood or other potentially infectious materials (OP!M);

• items contaminated with blood or OPIM and which would release these substances in a liquid or semi-liquid state if compressed;

• items that are caked with dried blood or OPIM and are capable of releasing these materials during handling;

• contaminated sharps; and

• pathological and microbiological wastes containing blood or OPIM.

With these standards in place, disposal devices generally accept the standard "red bag" used in the hospital environment. The device must be waterproof so that it can be cleaned easily and completely and those portions of devices that are in contact with hazardous materials must be formed of a material that is impermeable rather than porous.

Changing a bag in conventional devices can be both time consuming and inefficient due to their structure and configuration. Systems that require significant user strength are unacceptable in the hospital environment because much work is done by smaller persons. For example, on a percentile basis, in order to capture 99% of potential users, the device should be easily handled by a middle-age female.

Additionally, existing devices may preclude access to the full bag or to new bags, are sometimes improperly balanced, may not withstand the weight strain of an overly full or leaning load, do not offer any method of separating large and small biohazard materials, or provide a separate area for disposing of non ^" biohazard materials.

Additionally, loss of expensive metallic items such as tools, templates and other devices plague industries which are unrelated to medicine such as machine shops, automobile garages, assembly plants, laboratories, manufacturing plants and similar facilities. These industries will benefit equally to a newly improved waste cart.

Hence, a need exists for a waste cart capable of detecting metallic objects as they pass through the cart's openings.

Summary of the Invention

A waste cart comprising: a base housing, a center upright having a proximal end and a distal end where the proximal end is secured to the base housing, a top housing secured to the distal end of the center upright, the top housing having two or more disposal openings for two or more separate disposal portions, a first waste portion which has a first metal detector and an indicator system for providing a notification when a metal item is passes through the opening; a second waste portion which includes a second metal detector and an indicator system for providing a notification when a metal item passes through the opening, an electronics module which operates each metal detector independently or conjunction with each other and an alarm indicator

operationally associated with the electronics module which is activated whenever the electronics module detects the passage of a piece of metal into a waste portion.

Description of the Drawings

For the purpose of illustrating the invention, there is shown in the drawings a form that is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.

Figure 1 is a front view of one embodiment of the present invention.

Figure 2 is a top-down view of one embodiment of the present invention.

Figure 3 is a perspective view of one embodiment of the present invention.

Figure 4 is a side view of one embodiment of the present invention.

Figure 5 is a bottom-up perspective view of one embodiment of the present invention. Figure 6 is a bottom-up view of one embodiment of the present invention.

Figure 7 is an exploded side view of one embodiment of the present invention.

Figure 8 is an exploded view of the top components of one embodiment of the present invention.

Figure 9 is an exploded view of the tower components of one embodiment of the present invention.

Figure 10 is a bottom-up perspective view of the base of one embodiment of the present invention.

Figure 1 1 is a diagram of a detection algorithm of one embodiment of the present invention.

Figure 12 is a diagram illustrating an ADC reading showing a characteristic curve of one embodiment of the present invention.

Figure 13 is a diagram illustrating an ADC reading showing positive and negative deflections of one embodiment of the present invention. Figure 14 is a diagram illustrating an ADC reading showing a characteristic curve and sampling points of one embodiment of the present invention.

Figure 15 is a diagram illustrating an ADC reading showing a characteristic curve and a detection threshold window of one embodiment of the present invention.

Figure 16 is a diagram illustrating an ADC reading showing a characteristic curve and illustrating one embodiment of a positive deflection in the present invention.

Figure 17 is a diagram illustrating an ADC reading showing a characteristic curve and illustrating one embodiment of a negative deflection in the present invention.

Figure 18 is a diagram illustrating an ADC reading showing a characteristic curve and illustrating one embodiment of background compensation in the present invention.

Figure 19 is a diagram illustrating an ADC reading showing a characteristic curve and illustrating one embodiment of signal clipping in the present invention.

Figure 20 is an exploded perspective view of a method for holding the coils of one embodiment of the present invention.

Figure 21 is a perspective view of one embodiment of the present invention. Figure 22 is a perspective view of one embodiment of the present invention.

Figure 23 is an illustration of a perpendicular coil arrangement and the

associated detection fields of one embodiment of the present invention.

Figure 24 is a perspective view of a perpendicular coil arrangement of one embodiment of the present invention.

Figure 25 is a mid-level diagram of one embodiment of the present invention.

Figure 26 is a diagram of the master/slave synchronization setup of one embodiment of the present invention.

Figure 27 is a diagram of the installed wiring synchronization setup of one embodiment of the present invention.

Figure 28 is a side view of an RFID detector used in one embodiment of the present invention.

Description of the Invention

The present invention now will be described more fully hereinafter in the following detailed description of the invention, in which some, but not all embodiments of the invention are described. Indeed, this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein;

rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements.

The terminology used herein is for the purpose of describing particular

embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well as the singular forms, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one having ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. In describing the invention, it will be understood that a number of techniques and steps are disclosed. Each of these has individual benefit and each can also be used in conjunction with one or more, or in some cases all, of the other disclosed techniques. Accordingly, for the sake of clarity, this description will refrain from repeating every possible combination of the individual steps in an unnecessary fashion. Nevertheless, the specification and claims should be read with the understanding that such

combinations are entirely within the scope of the invention and the claims.

Looking at figures 1 through 10 and 20-22, there is illustrated one embodiment of a movable waste cart 10 which is capable of detecting metallic objects as they pass through the cart's openings 56. The waste cart 10 is comprised of a mostly non-metallic composition. The waste cart 10 is comprised of three primary sections which include:

(1 ) a base housing 20 which is proximally closer to the ground,

(2) a center upright body 40 which is the region disposed between the top housing 50 and base housing 20, and

(3) a top housing 50 which is the region furthest vertically from the base housing

20.

The base housing 20 includes an upper surface 22 and a lower surface 24. The center upright body 40 is secured to and emanates upward from the upper surface of the base housing 20. A battery cover 25 is located on the lower surface of the base housing. In one embodiment of the instant invention, the base housing 20 is essentially hollow and includes an inner cavity 30 which houses some or all of the electronic components utilized by the waste cart 10. In another embodiment, the inner cavity 30 houses the electronics module 90, battery 91 , and other electrical components.

The center upright body 40 has a proximal end 42 and a distal end 44 where the proximal end is secured to the base housing 20 and the distal end is secured to the top housing 50.

The top housing 50 is mainly circular in nature and is bisected with two or more openings for two or more separate disposal portions. The openings may be symmetric. A first waste portion 70 has a first metal detector 71 and an indicator system (65, 67) for providing a notification when a metal item is passes through the opening. A second waste portion 75 which includes a second metal detector 76 and an indicator system for providing a notification when a metal item is passes through the opening. An electronics module 90 which operates each metal detector (71 , 76) independently and an alarm indicator (65) operationally associated with the electronics module which is activated whenever the electronics module detects the passage of a piece of metal into a waste portion (70, 71 ). In one embodiment of the instant invention, two alarm indicators 65 are situated along the bisection line for visual indication. The top housing 50 is made up of a top coil housing 52 secured to a bottom coil housing 54 leaving a hollow cavity within to house the transmitter coil(s) and receiver coil(s). The bottom housing 54 is secured to the distal end 44 of the center upright body 40. Bag supports 61 are situated at the two furthest points along the bisection line 62 of each of the bisected openings 56 of the top coil housing 52 to aide in holding of an inserted waste bag 64. The bag supports 61 make use of friction to help maintain a bag 64 in position after it has been secured in to an opening of the waste cart 10. One embodiment includes a plurality of bag supports 61 located along the upper surface of the top coil housing 52. The top housing may also include a plurality of bag retainers 63 (Figs. 3 and 4). The bag retainers 63 function by a person pushing part of the bag 64 within the bag retainer 63 and the spring action of the bag retainer helps to maintain the bag in position. Ensconced within the top housing 50 is a set of three coiled lengths of electrical wire. One of the coils, the transmitter 100, encircles the full perimeter of the top housing 50. Each of the remaining two coils, the receivers 1 10, are disposed singularly around the perimeter of each of the bisected openings 56. The center upright body 40 provides structural support for the top housing 50 and providing a means for containing the electrical connections between the top housing 50 and the base housing 20.

As stated previously, the electronics module 90 is contained within the base housing 20. The electronics module 90 is connected (operationally associated) with the coils 100, 1 10 and connect to a plurality of visual alarm indicators 65 on the top housing 50 and to an audio alarm indicator 67 (i.e. a speaker) which provides auditory indication when a metallic object passes through an opening 56. In one embodiment of the instant invention, logic is provided to automatically power down the waste cart 10 after a defined period of time in order to conserve battery power. A means for powering the waste cart 10, while connected to structural power (i.e., a wall outlet) or while mobile, are provided within the base housing 20. The waste cart 10 can be powered either by being plugged into structural wiring or via an internal battery when not plugged in. The switch over from one power source to another occurs without the intervention of the user and does not affect the operation of the system. A plurality of caster wheels 35 are attached to the lower surface 24 of the base housing 20 to allow the waste cart 10 to be easily moved. In one embodiment of the instant invention, the cart is intended to be used as the primary location for disposal of all objects not considered to be defined as sharps. In another embodiment, the cart is intended to be used as the primary location for disposal of all objects, including those defined as sharps.

The motion of a conductor (i.e., a metallic object or any materials that will conduct electricity) through a magnetic field results in minute currents beginning generated within the conductor. As the object passes through the electric field, there is an electrical current induced in the object which can then be detected by the cart 10. The magnetic field can be generated by a permanent magnet or by the application of the flow of electricity to a coil of conductors. As a conductor enters in to the magnetic field, the field will induce currents of electrons that will swirl within the conductor much like the small swirling currents in a flowing body of water. These currents remain as the external field exists. If the field is removed, the currents within the conductor will remain temporarily. As there is no input of energy to support the currents, the currents will decay over a period of time. With conductors possessing high conductivity, these currents will decay slower than those in a lower conductivity conductor. With the external field removed, and before the currents have disappeared, the eddy currents will themselves develop a magnetic field. In the opposite manner of energizing a coil to produce a magnetic field, if a coil of conductors is placed within a magnetic field, a voltage will be generated along the length of the coil. This theory is used to detect the presence of metal near a conductor coil.

There are two primary methods for utilizing these components to detect metal; continuous wave (CW) or pulse induction (PI). In a CW system, a continuous signal is generated by a coil transmitter which develops a magnetic field around the coil. A receive coil 1 10 is able to pick up the sign from the transmitter and the two signals are compared. If an object that can carry a magnetic field enters into proximity to the transmitter, the signal between the transmitter 100 and the receiver 1 10 is disrupted. This disruption is the basis for CW detection systems.

A system operating on a PI will pulse an environment generating a cyclic magnetic field (Fig. 23). When the transmit coil 100 is turned off, any conductor that was within the transmit coil's magnetic field will generate a magnetic field as it decays. A receiver coil 1 10 is able to then detect the decaying magnetic field from the object and in the control system is able to distinguish that an object was present. Figure 23 illustrates the pairs of magnetic fields 120. Looking now to figure 24, there is illustrated an embodiment of the perpendicular coil arrangement 1 15. Looking now to Figure 25, there is illustrated a mid-level diagram of one embodiment of the present invention. Figure 25 includes an illustration of the electronics module 90 which is operationally associated with an acceleration motion detection module 83. The electronics module 90 is operationally associated with switch 80 and one or more visual power indicators 81 . Electronics module is also operates only associated with a visual motion detection camera 82 which aids in deactivating the detection process while the cart 10 is in motion. Figure 25 also details and arrangement of the transmit coil 100, a pair detection coils 1 1 0, a pair of detection indicator 65, a pair of perpendicular coils 1 15 and an audio alarm indicator 67, all of which are operationally associated with the electronics module 90. Also included. Figure 25 are the main plug 85, the cord real 86, a fuse 87, a power supply 88 and a battery 89.

The current waste cart 10 is an improvement on a previous version of a metal detecting waste bin. The previous version of the device consisted of a single opening with all circuitry and components contained within the top cap of the cart. The device operated on the CW system of metal detection and could only reliably detect ferrous objects. The cart contained a counter, on/off switch and a variety of other controls. The cart required a calibration period that was approximately 30 seconds.

The instant invention demonstrates the following improvements over the existing art: - The waste cart 10 now has the ability to detect both ferrous and non-ferrous objects which include but are not limited to iron, steel, stainless steel, titanium, copper, aluminum, silver and gold.

- The waste cart 10 is able to discern between high conductivity objects such as aluminum and lower conductivity objects such as steel.

- The waste cart 10 has the ability to retain a significant ability to detect objects while in close proximity to environmental interferers. This is achieved by measuring the response from the receive coils and adjusting the threshold gain accordingly. Essentially increasing the ADC range in figure 19

- The waste cart 10 needs only a very short period of time from completely off to be ready to detect (in the range of 0.1 to 10 seconds, 0.1 to 6 seconds, 0.1 to 4 seconds, 0.1 to 2 seconds, or any combination thereof).

- One embodiment of the waste cart 10 possesses two openings which can be configured to detect on both sides or be set to detect on a single side.

- The design of the waste cart 10 facilitates the full use of the volume of a waste bag 64 allowing it to bulge beyond the perimeter of the base housing 20 and top housing 50 of the waste cart 10.

- The design of the waste cart 10 removes the need to lift a potentially heavy

waste bag vertically out of the bin, and instead allows a bag to be removed, horizontally.

- The waste cart 10 is turned on with a kick switch.

- The only task a user must do to bring the waste cart 10 to full operation is to kick the on/off foot switch. - The waste cart 10 possesses an RFID reader which is able to read RFID tags as they pass through the openings 56.

- The waste cart 10 possesses the ability to disable the alarm if the cart is being moved within a room.

- The waste cart 10 has the ability to be configured with multiple sets of coils 100, 1 10 which can be turned on to reduce the detection window to help reduce external interferer influences.

o In one embodiment of the instant invention, turning on additional coils refers to the optional perpendicular coils (1 15). The perpendicular coils possess a detection field which is perpendicular to the standard

orientation (100 and 1 10). Using some signal processing, the perpendicular detection field can be used to validate a detection vs external interferers such as rebar in the floor. The effect is much like a Venn diagram of the sets of detection fields which help to narrow the spatial detection field.

One embodiment of the instant invention discloses a waste disposal system 10 comprising a base housing 20, a center upright body 40 which has a proximal end 42 and a distal end 44, the proximal end 42 is secured to the base housing 20, a top housing 50 is secured to the distal end 44 of the center upright, the base housing 20, center upright body 40 and top housing 50 each is formed of a material that is amenable to disinfectant in the hospital environment and having surfaces contoured for easy cleaning in the hospital environment. The top housing 50 has at least two separate disposal portions, with a first waste portion 70 for waste other than sharps, the first waste portion 70 having an opening 56 large enough to receive waste that is typically other than sharps in the hospital environment and a second waste portion 75 for waste other than sharps, the second waste portion 75 having an opening 56 large enough to receive waste that is typically other than sharps in the hospital environment. A barrier 58 separating the first waste portion 70 from the second waste portion 75 within which a metal detector is located and an indicator system for providing a notification when a metal item is unintentionally placed in the opening, wherein the metal detector includes a receiver coil 1 10 and a transmit coil 100 oriented perpendicular to the passage of waste to allow for more accurate detection in the passageways while simultaneously limiting the detection above and below the coils. An electronics module 90 which operates each metal detector independently of one another and an alarm indicator , 65, 67 which is operationally associated with the electronics module 90 which is activated whenever the electronics module detects the passage of a piece of metal through one or more of the waste openings 56.

In one embodiment, the above waste disposal system may be configured wherein the coils are set up in either a constant wave (CW) configuration or a pulse induction (PI) configuration. In another embodiment, the waste disposal system utilizes a quadrapole arrangement, wherein a single transmit coil 100 encircles both the first waste opening 56 and the second waste opening 57 and a first receive coil is set to detect metal and a second coil is set to cancel external effects. In still another embodiment, the above waste disposal system further includes a blocking shield to help isolate one region magnetically from another. The blocking shield is comprised of Mu- metal.

Metal Detection

The control circuitry operates in a cyclic nature with a detection period

representing a transmitted pulse, sampling of values and accessory processes. Each detection period lasts 10 milliseconds or a rate of 100Hz.

Looking to Figure 1 1 , there is illustrated one embodiment of a detection algorithm used in the present invention. The detection cycle starts at step 140 with the energizing of the transmitter coil (as seen in Fig. Error! Reference source not found.12). Step 141 represents an increase in the startup counter which records the number of times the cart 10 has started up. Step 142 represents the calibration and setting the reference number and calibrating the digital to analog converter (DAC) to center. Step 143 represents the end of a transmitted pulse. Step 144 represents the acquisition of an analog to digital converter (ADC) value , which then leads to step 145 wherein it is determined whether that value is greater than center value set in step 142, taking into account a standard deviation. If the ADC value in step 145 is greater than the center reference the startup counter is reset and the DAC value is determined (step 147). The DAC value equals zero, then we move on to step 148, which is to increase the center. Proceeding to step 149, where it is determined whether the reference is less than 250. If it is not then there is an inability to detect (step 150) and if it is then we returned to step 144, with an acquisition of the ADC value. If the DAC value from step 147, does not equal zero. Then we proceed to step 151 , wherein there is a decrease in the RX input voltage, which takes us to step 2, wherein the ADC value is taken. If the ADC value is not less than the center value, taking into account standard deviation, and we proceed to step 153 which determines whether the value is greater than the center minus the acceptable deviation. If the result of step 153 is negative, then we move on to step 160 which is no detection. If the result of step 153 is positive than the startup counter is reset and we move on to step 154, where it is determined whether the DAC value is equal to 255. The answer is yes, then we move on to step 157, which is to decrease the center. Proceeding to step 158, where it is determined whether the reference is less than 5. If it is not then there is an inability to detect (step 159) and if it is, then we returned to step 144, with an acquisition of the ADC value. If the DAC value is not equal to 255 in step 154, we proceed to step 155 which is to increase the PIC input voltage. We then proceed to step 156, where in the ADC value is taken after which we returned to step 153, to determine whether the ADC value less than the center value minus the standard deviation. In one embodiment of the instant invention, steps 147 through 151 are utilized as background compensation.

In Fig. 12, the solid black line represents the value read from the sum of the two detection coils 100, 1 10, this is the ADC value. This read value is a conversion of analog voltage level from the sum of the two detection coils 100, 1 10 being processed through an Analog to Digital Converter (ADC) 130. The physics relating to the ADC limit the range the ADC can read which shows as the flat line when the transmitter is operating. Once the transmitter is turned off, there is a period where the ADC is shut off to let the electronics settle. After a period of time, the ADC is turned back on. The solid black line illustrates the characteristic detected voltage curve read by the ADC without detectable object within the detection field.

The two detection coils 100, 1 10 are balanced and operate in unison to discriminate the detection side. The coils are balanced to assist in the fine

discrimination of changes of voltages. A metallic object passing through the field of the coil connected to the positive leg of the summing junction would result in a positive deflection of the ADC value. Conversely, as a metallic object passes through the detection coil connected to the negative leg of the summing junction, the result would be a negative deflection in the ADC value. This behavior is shown in Fig. 13. The entire curve deflects as a metallic object passes through either of the detection coils, but there is generally a proportionally greater change in the ADC value closer to the shut off of the transmitter than there is farther from the transmitter shutoff.

The system operates very quickly and processor time must be managed appropriately to ensure accurate readings. Rather than take ADC values along the entire detection period, sampling values are established, shown in Fig. 14. The vertical lines S1 , S2, and S3 represent a system with 3 sampling points, however, additional or fewer points can be read. The vertical lines illustrate the period in time when an ADC value is taken. The circular dots in Fig. 14, are representative of the ADC value being read. In an effort to reduce noise which is present in any system, the averages of these points are taken over a period of sixteen samples. There is a trade off in performance when averaging the samples. A sample occurs each detection cycle, therefore averaging sixteen samples requires sixteen cycles to transpire. If there is a detectable value that is read, that value must be present in the detection filed long enough for its effect to pass through the averaging processing and register a detection. If too many samples are used, the system could miss quickly traveling objects. If too few samples are taken, the effect of noise can lead to false positives. The system relies on sensitive electronics looking at very minuet deviations in voltages which make noise a significant factor in the performance balancing.

For discussion of detections, this description will be referring to sampling point "S1 " in the figures but the sample statements hold true to any of the detection points. The system acquires the averaged ADV values at each of the sample points. These averages become the resting value. If the average deviates from this value, the system recognizes the behavior as a detection caused by a metallic object passing through one of the coils. Noise is still a factor, even with averaging, which to compensate a deviation window is established. Fig. 15 The ADV value may vacillate within this window without causing a detection. If however, the value is great enough, the system will recognize this situation as a detection 131 . This deviation can either be positive Fig. 16 or negative Fig. 17 depending on which detection coil the metallic object has passed through. The detection circuitry reads any field generated by any metallic object. This may be a metallic object passing through the detection coils 100, 1 10 or it could be an object next to the device, defined as an interferer. Under ideal operating conditions, the system is set so the signals within the detection coils 100, 1 10 are far greater than that of the surrounding objects. Significantly large interferers or quantities of interferers in close proximity to the detection coils can appear as if they were an object passing through the detection coils and signal a false positive. To address this issue, the system takes advantage of the difference in time base between a proper signal and interference from the environment. An object passing through the openings as if it were being thrown away will have a relatively quick transient change when compared to the signal change of the entire waste cart 10 being moved around a room. If the cart is moved in close proximity to a large interferer, the control system will recognize a change in ADC value and signal a detection. As the ADC value remains the same, the system will recognize this value as most likely an interferer and adjust its threshold value 132 to establish a new reference value with a proper window as shown in Fig. 18. In Fig. 18 the solid grey line represents the previous characteristic ADC response. The dashed grey line represents the characteristic signal when the cart is placed next to an interferer. The detection window is adjusted by the system to compensate for the change in

environmental response.

There are instances where an interferer may be too close or too powerful of a response that the signal reaches the limits of the ADC and the signal becomes clipped Fig. 19. This clipping is unavoidable since the ADC can only operate within physical limits of the chip. In the case illustrated in Fig. 19, any further deflection of the curve will not be seen by S1 or S2 since they are within the clipped region. The signal at S3 however, still retains some of its ability to detect changes and can therefore still detect certain larger objects passing through the coils. If the cart ends up in a situation where it is not able to perform properly 133 it will let out a cycling tone to let the user know it is not able to operate correctly.

Perpendicular Coils

The current coil arrangement places the coils in a plane parallel to the ground. In this orientation, the detection circuitry and coils are more sensitive to metallic objects both above (towards the ceiling) and below (towards the floor) the coils. To help reduce the influence of interferers, a second set of coils, deposed perpendicular to the coils parallel to the ground (Figures 23 and 24) can be activated. The overlap between the two operational sets of coils acts to define the region of most sensitive detection. The theory was tested via setting a commercial coil based metal detector product in this arrangement. The detector was not sensitive to metallic objects in the floor or ceiling but possessed a higher sensitivity to metallic objects about the circumference of the main detector coils. In one embodiment of the present invention, both sets of coils operate in alternate turns of detection. A logic scheme was constructed that coordinates the detection of both sets of coils, effectively narrowing the detection space to an optimal size. Cart Movement Sensing

A metal detector relies on the disturbances of electrical fields to determine if a metallic object is present or not within its field of detection. This operation makes it nearly impossible to distinguish between a metallic object being moved into the field or if the field is being moved into close proximity of the detector. This situation is pertinent to the current device in that if the device is moved into close proximity to a metallic object, say a table or cabinet, the detector will register this object as a detected object and signal detection. This detection is undesirable in that the waste cart 10 is intended to detect objects passing into the field surrounding each opening 56 at the top of the cart. A detection resulting from the waste cart being moved into close proximity of a metallic object would be viewed as a false detection and appear as an error in the cart. To address this issue, methods (82, 83) have been implemented to disable the detection function while the cart is in motion.

One of the methods for disabling the alarm while the cart is in motion is by means of an accelerometer 83. The accelerometer sensor disables the detection notification while the cart is being moved from one location to another. It has been assumed that while the cart is being moved, there is a small likelihood of a user passing an article of waste through the detection field. Assuming this is the case, since the sensor will disable the detection notification while in motion, it will not be apparent to the user if they move the cart into close proximity to a metallic object thus causing the circuitry to register a detection as it was a false detection to begin with. Another method for detecting motion of the cart is with a downward facing optical detector 82. This detector registers the surface of the floor. If the cart is moved, the detector will disable the detection notification until the cart has stopped moving and the detector recalibrates to the new environment. The detection would be disabled while the cart is in motion and would also be disabled during the calibration once it has stopped.

Either method is able to disable the alarm while the cart is in motion. However the detector notification is accomplished, it has been identified that it may be

advantageous to signal the user that the cart is in motion and any articles passed through the cart will not be signaled. This signaling can be visual or auditory.

Cart Cross Talk

In one embodiment of the present invention, two waste carts 10 exist in a relatively close proximity to one another. When this occurs, each cart has the ability for one cart to create a false detection on another cart. Methods for dealing with this cross talk have been explored. As described earlier, each cart accomplished metal detection through creating a magnetic field by applying an electrical current through a wire loop for a short amount of time. Once, the current is shut off, the cart records the magnetic fields of any metallic objects within proximity to the cart. This scheme happens in a cyclic fashion at a set frequency. If two carts are placed in close proximity of each other, the likelihood of the detection cycles overlapping is small as the detection cycle is a small percentage of the frequency period. As systems are not perfect, the frequency on one cart will be slightly off from another cart. This will cause the detection point in one cart to drift in relation to another cart. If one cart happens to be recording the magnetic field of the surrounds looking for metallic objects when the other cart is creating a magnetic field, a detection will be recorded on the first cart. It is thus imperative that the detection period for each cart is kept away from the detection period of the other cart.

The most basic method at achieving interval spacing has been utilizing the 60Hz AC wall power signal to acts as a clock for all of the systems. There are generally three phases of power that enter a building. Each of the phases is 120 degrees out of phase with the next. The carts could use the AC wall frequency to set when the signaling and detecting phases occur and not interfere with other carts (shown schematic in Figure 27).

A more complex method of detection spacing involves the carts being able to communicate with other carts nearby. Through a wireless protocol, a cart would be designated as a master cart 170 charged with setting the detecting timing for any carts (slave carts, 175) within distance of the master cart 170 (shown schematic in Figure 26). With the detection timing set and actively monitored, there would be less likely for the chance of false detections due to cross talk.

Power Line Filtering

The installation wiring and associated electrical equipment result in a relatively noisy environment for the metal detectors to operate in. To combat this issue, the frequencies of the power lines have been selectively filtered out. This allows for more consistent operation across multiple environments.

Isolation of Detection and Power Circuitry

When powered from installation wiring, the unfiltered power causes noise in the detection system. To help compensate for this noise, the detection circuitry and power handling circuitry is electrically separated. This results in higher achievable accuracy and less false detection.

RFID (radio-frequency identification)

It was determined through operational studies that it would be advantageous for the carts to be able to track items with attached RFID tags. This would allow for the carts to detect and track items which may not be metallic but their passage into the trash to be detected. To accomplish this, the carts are fitted with an RFID antenna and detection circuitry (Figure 28). As an RFID tagged item passes through the opening, the RFID circuitry energizes the tag. The tag broadcasts the information on the tag. The RFID circuitry 125 detects the broadcasted information and is able register the item has passed through the opening and into the waste bag.

The invention described herein also includes any method of using the waste cart/ medical waste disposal system to detect metallic objects and/or prevent the loss of equipment and supplies. Any method described herein may incorporate any design element contained within this application and any other document/application incorporated by reference herein.

In one embodiment of instant invention, the waste cart 10 is intended to be used in the operating room after a surgery has been conducted and the patient has been removed from the room. It has been determined that valuable equipment is being accidentally and/or inadvertently thrown away during the clean up after a medical procedure. This loss is accidental wherein equipment becomes lost with the medical drapery used in a medical procedure and is not found by the time the drapes have been thrown away. The waste cart 10 has been designed to help mitigate the loss from this modality.

In another embodiment of the instant invention, the waste cart 10 is intended to be used within any environment where valuable items which have a metallic component capable of being detected by a waste cart as described herein. Those environments include, but are not limited to, machine shops, automobile garages, assembly plants, laboratories, manufacturing plants and similar facilities.

In one embodiment, the waste cart 10 is fit with two waste bags 64 about the two openings 56 on the part. A bag 64 is passed over the two bag supports 61 at the corners of one of the half circle openings 56. The bag 64 is pulled taught, twisted near one of the outer perimeter bag retainers 63 and pressed into the bag retainer. The waste cart 10 will be used as a standard waste receptacle prior to and during a procedure. At the conclusion of a procedure, the patient is removed from the room and the cleanup commences. Once the patient has been removed the waste cart 10 is positioned for ease of use. The cart is then turned on via the power switch 80 (i.e., kick switch). A visual indicator (not illustrated) on the sides of the cart will illuminate when on to signal to the user that the part is ready to receive waste. The cart is then ready to detect metallic objects passing through it. To the user this appears instantaneous, not requiring a long calibration period prior to use. Waste is placed into the opening 56 of the cart as it would be a normal waste receptacle. If a metallic object passes through the opening, 56, an audible tone will be played through the speaker 67 and the visual indicators 65 on the top housing 50 of the cart will light up. After all waste has been disposed of or when a bag 64 has been filled, the technician removes the bag from the bag retainer 63 on the side of the top housing 50 and pulls the full bag from the side of the cart. A fresh bag can be replaced if desired or necessary. The waste cart 10 is wiped down to clean any foreign matter from its surface and turned off. If the waste cart 10 is not turned off, it will automatically turn off if left without a detection for 15 minutes. A retractable power cord can be extended to reach the nearest power receptacle for charging of the internal battery.

In another embodiment, the instant invention includes a method for detecting metallic objects as they pass through a waste cart 10 including the steps of:

(a) providing the waste cart 10 comprising a base housing 20, a center

upright body 40 which has a proximal end 42 and a distal end 44, the proximal end 42 is secured to the base housing 20, a top housing 50 secured to the distal end 44 of the center upright 40, the top housing 50 has two or more disposal openings 56, 57 for two or more separate disposal portions, a first waste portion 70 for waste other than sharps which has a first metal detector 71 and an indicator system for providing a notification when a metal item is passes through the opening, a second waste portion 75 which optionally includes a second metal detector 76 and an indicator system for providing a notification when a metal item is passes through the opening, an electronics module 90 which operates each metal detector independently of one another and an alarm indicator 65, 67 operationally associated with the electronics module 90 which is activated whenever the electronics module 90 detects the passage of a piece of metal through one or more of the waste openings 56, 57;

(b) activating the electronics module 90 and metal detectors 71 , 76;

(c) collecting waste generated during a procedure by placing the waste through the disposal openings into either the first 70 or second 75 waste portion;

(d) activating the alarm indicator in the event that one of the metal detectors indicates the passage of a metallic object though a detection field;

(e) retrieving the metallic object from the first 70 or second 75 waste portion;

(f) repeating steps (b) through (e) until the desired waste is collected.

In one embodiment, the waste disposal system used in the above method may be configured wherein the coils are set up in either a constant wave (CW) configuration or a pulse induction (PI) configuration. In another embodiment, the waste disposal system used in the above method utilizes a quadrapole arrangement, wherein a single transmit coil 100 encircles both the first waste opening 56 and the second waste opening 57 and a first receive coil is set to detect metal and a second coil is set to cancel external effects. In still another embodiment, the above waste disposal system used in the above method further includes a blocking shield to help isolate one region magnetically from another. The blocking shield is comprised of Mu-metal.

Regarding step (c) of the method described herein, a "procedure" encompasses a variety to tasks including a medical or surgical procedure, the manufacture of a device or component, the assembly of a device or component, the repair of a device or component, or any other activity within any environment where valuable items which have a metallic component capable of being detected by a waste cart as described herein.

In describing the invention, it will be understood that a number of techniques and steps are disclosed. Each of these has individual benefit and each can also be used in conjunction with one or more, or in some cases all, of the other disclosed techniques. Accordingly, for the sake of clarity, this description will refrain from repeating every possible combination of the individual steps in an unnecessary fashion. Nevertheless, the specification and claims should be read with the understanding that such

combinations are entirely within the scope of the invention and the claims. The present invention may be embodied in other forms without departing from the spirit and the essential attributes thereof, and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention. The invention illustratively discloses herein suitably may be practiced in the absence of any element which is not specifically disclosed herein.