Patent Grant
7693603
The invention describes improved methods and mechanisms for providing secure access to pharmaceutical and supply items in a clinical setting.
In large medical facilities, the main inventories of pharmaceutical items are held in storage locations which are often far removed from the patients who use them. To facilitate secure and accurate delivery of the pharmaceutical items from these storage locations to the patient, a variety of systems have been proposed and put into use. In earlier systems, referred to as a “cart exchange” system, medication carts are distributed at nursing stations in the medical facility, remote from the central pharmacy, and are periodically exchanged with fully supplied carts. Typically these carts contain a 24 hour supply of medications sorted by patient into specific drawers. The “used” cart is returned to a central pharmacy of supply area where the next 24 hours of medications are replenished. Narcotics, are stored in locked boxes on the floor, requiring two nurses with separate keys and a written log, for management.
While the cart exchange system is still in use for some medications, shorter hospital stays mean that the majority of patients are more critically ill, resulting in a changing regimen of medications throughout the day. This results in many new orders needing to be brought up from the central pharmacy during the day, and a large amount of unused medication being returned. The re-stocking of these medications needs to be done accurately, and is very time consuming. As a result there has been an increasing use of automated, processor based, cabinets on the nursing floors. The processor on each cabinet monitors the access to the pharmaceutical items in these fixed cabinets, allowing the current on hand inventory and the need for replenishment to be communicated to a central processor at the central pharmacy location. These processor based dispensing cabinets were initially used for the more convenient management of narcotics, and for the ability to have a “floor stock” of common medications from which a nurse could issue the first dose of a needed new prescription, while waiting for the 24 hours supply to come up from pharmacy in the exchange cart, or on a special order basis.
Over the last eight years or so, these processor based cabinets have expanded to offering the possibility of storing the majority of medications that the patients on the floor might need during the day and night. These medications are stored in pockets within locked drawers. In other words stocks of medications are maintained at a desired par level in non-patient specific form. This is referred to as “Floor Stock”. A nurse, upon entering their own personal ID, and the ID of a specific patient, will see the medications that are approved overall for that selected patient, referred to as “The Patient Profile”, and in some systems, will also see what medications are due at that particular time, referred to generally as “Due Medications”. The task for the central pharmacy, then, moves from selecting and filling exchange carts with a 24 hour supply of medications to each patient, to using the central processor to monitor the on-hand stock of the medications stored in the cabinets, and restocking those levels at regular intervals. A big advantage of this process is not having unused doses of medications returned to the central pharmacy. It also means that first doses (as well as subsequent doses) are immediately available.
In the final analysis, a mixture of the two systems is needed. There are still many situations that continue to require medications to be brought from central pharmacy For example, to avoid medication errors, intravenous fluids (IVs) that contain medication are now increasingly being mixed in the pharmacy and brought up to the floor for safety reasons, rather than being prepared by nurses by attaching a so-called piggy-back back medication bag, to a standard diluent bag. There are also specialized, or infrequently used medications, or those with short life, or requiring refrigeration, or that need special handling from the pharmacy. Finally there is the consideration of the time it may take nursing to select unit doses of medication at regular intervals through the day, rather than taking from a small collection of medications pre-selected by the pharmacy for a specific patient.
In addition these cabinets have provided a variety of means to only allow qualified users to have access to the cabinet, and to restrict the access of qualified users only to items to which that particular user is permitted to have access, or at least to track if users are accessing areas that are not required for the particular patient.
These cabinets also provide means to guide the user to the right pharmaceutical that is being requested, either by an indicator, which is usually a light adjacent to the pocket, or by pre-opening a locked drawer and a locked lid, the sprung lid indicating which pocket the medication of interest is in. These cabinets also provide a record of the access to that particular pharmaceutical, where that access can be detected (as is the case with the lifting of a lid that has a sensor attached).
The ideal system would only allow the user access to the single specific dose of medication requested. This is for two reasons. To ensure that only that medication is taken, as for example in the case of narcotics, where an addicted user might wish to divert extra doses for their own use. The second reason is for patient safety, to ensure that the right medication is selected. However for reasons of cost, manufacturers have provided a variety of drawers, each with different levels of restriction, and the choice is ultimately a trade off between cost, and accuracy and security.
As discussed, the ideal system would allow the user only to access the single specific dose of medication requested. In some systems, this has been provided by having metered drawers. These are drawers that have multiple doses of the same medication, but which open just enough to reveal the one, or “N” doses, requested and no more. Other systems have provided a dispenser, much like a candy or cigarette machine, that dispenses the requested medication using a rotating coil or a solenoid operated cassette, to drop just that medication into a tray that is accessible to the user's hand. A third method uses individually locking drawers, housing pockets with locked lids, each pocket containing just a single dose of a medication. These mechanisms are currently cost prohibitive for lower cost, lower security medications.
The next level of security is to use individually locking drawers, housing pockets with locked lids, each pocket containing multiple doses of a single type and dose of a medication. In accessing these medication doses, the other pockets remain locked, so the nurse is not able to take the wrong medication. They may however take the wrong quantity of the selected medication, either in error or, in the case of narcotics, for their own use. Various software systems have been provided to track the users' access and steps as much as possible, in order to track patterns of use that might indicate either erroneous access, resulting in the user taking the wrong medication, or deliberate diversion of medications. These software techniques often involve additional steps for the user. In the case of this locked pocket with multiple doses of the same medication, these software steps may include requiring that a second user be found, to act as a witness, and/or counting back the number of remaining doses in that multi-dose pocket. In the case of “count-back”, if a user finds an error—for example the quantity in the pocket is less than the processor thinks is in the pocket, which would be the number entered by the previous user in counting back—then, either the current user or the previous user has either made a mistake, or has intentionally diverted one or more doses. The problem with this approach is that taking the medication is not prevented, and analysis of the error is done later on, usually at the end of the nurses' shift, after the fact, and does not point to the specific single culprit who made an error or deliberately diverted. It requires tracking down the two parties concerned, and having at least one of them feel “wrongly accused”, and never having specific evidence. All these steps increase the time take to take the medication accurately and securely.
Another type of individually locking drawer uses multiple doses of the same medication in pockets with lids, but without locks, in order to reduce cost. The processor will monitor if a user accesses a pocket with medications that were not selected for the patient, and will record this as an incorrect access in an audit trail. But this is less desirable than a locked lid, since the access is not prevented, but entered into an audit trail in the processor, requiring someone to review the audit trail after the fact, find the culprit and discuss why they made that access, and ask if they took anything they shouldn't. A countback process can also be added with its advantages and disadvantages. It can be understood why it is preferable to prevent access in the first place.
Another type of locking drawer, referred to as a “Matrix Drawer”, opens to reveal a “matrix” of open pockets, each pocket with multiple quantities of a single medication. While the individual drawer may be locked, the security and safety issue in this case is the fact that there is no mechanism to prevent access to medications that have not been preselected in the processor for the patient, leaving open the possibility for the nurse user to take the wrong medication in error, or to take additional medications undetected.
A focus in the last five years has been the desire to use bar code checking at the point of administration at the bedside of the patient, to avoid administering the wrong medication to the wrong patient. To this end, unit doses of medication are all being bar-coded, either by the manufacturer or by the central pharmacy in packaging machine, if the medication has been bought in bulk. In some cases, checks that have evolved at the dispensing cabinets, are more appropriately done at the bedside. With the desire to have the majority of medications available in a cabinet at the nursing station, and with the increased focus on patient safety, it is the purpose of the inventions presented here, to make the cabinets more cost effective and to increase the accuracy of the dispensing process.
While the current systems provide working methods for securely issuing medications it would be desirable to reducing the potential cost of the cabinet drawers, allowing more items to be kept in more secure single dose dispensing mechanisms or single dose drawers, or that at least have more items be kept in locked and/or lidded containers, so that the processor knows that the user is accessing the correct location. In addition it would be desirable to provide mechanisms to provide better detection of, and deterrence from, diversion in drawers that allow access to multiple pockets and/or multiple doses. It would also be desirable to ensure, particularly in the case of pockets without locking lids, that the nurse is accessing the right medication, and not accessing the wrong pocket either deliberately or inadvertently, and is taking the right quantity of those medications, and to provide means to confirm to the nurse that they are taking the right medication without introducing additional steps.
In addition to the safety aspect of taking the right medication, there is also the security aspect of ensuring that the wrong medication is not deliberately taken. In many cases, the users are having to obtain narcotic items, and the pharmacy and nursing department have serious obligations to prevent diversion. It is much preferred to prevent diversion, either by having more unit doses of medication in locked pockets, or by having better deterrents to diversion. Some of this can be achieved by lowering the cost of the cabinet and so being able to cost effectively keep more narcotic items in single dose, locked pockets. But it is also desirable to have improved mechanisms and methods to record and know after the fact, what each user did at the cabinet, both to record who the user really was, in case they are using a stolen identification, and to observe and record their actions in accessing medications in the drawers themselves, and also to inform the users that their actions are being recorded on video for example, as a deterrent to them attempting to divert.
Finally, with the increasing deployment of these systems, their availability has become mission critical and it is highly desirable to increase the systems ability to aid the nurse in the dispensing process if there are any problems or questions, and to reduce the MTTR (mean time to repair) in the event of a failure.
The invention describes improved methods and mechanisms for providing secure access to pharmaceutical and supply items in a clinical setting. In one version of the invention, a dispensing unit has an interior housing one or more drawers. Each drawer has one or more storage locations, referred to as pockets. The fronts of the drawers are covered with one or more locking doors, preventing access to a particular drawer, unless the covering door is unlocked. Indicators are mounted on the side of the enclosure, to guide the user to a drawer covered by an associated unlocked door. The unit further includes indicators on the sides of the drawers, to guide the user to the right storage receptacles or pockets within the drawer. Some pockets may have lids. Some of the lids may have locks. Sensors associated with at least some of the individual pocket lids may be provided to detect the lifting of a lid. Means to automatically detect the entry of a hand or fingers into a pocket may be provided. There may also be locked modular drawers that are not covered by doors, whose purpose is to issue doses one at a time, and which will only open to reveal a single dose to be taken. One or more loudspeakers may be mounted on the unit, to provide auditory guidance and confirmation of correct access, by sounds and voice prompts. One or more video cameras may be mounted on the unit. A processor is mounted in the unit, or, in the case of an auxiliary unit, the auxiliary unit is connected to the processor on the main unit. The processor is connected to receive signals from sensors in the dispensing unit, from the video camera, and to send signals to the indicators, and to send auditory information to loudspeakers which are designed to focus the sound specifically to the user.
In an exemplary embodiment, a user enters their identification into the processor, which may be done at a keyboard, or at a touch screen, or utilizing a biometric identification system such as a finger-print reader. The processor has a data base that knows whether the user is authorized to access the cabinet or not. The user then selects a patient from a list of patients that is updated periodically from a main processor that retains the census of patients from the hospital, and which is stored in the local processor on the cabinet. Or the user may enter the identification number of a new patient not yet in the system, or set up a new patient with a temporary identification number for the interim time until the patient data is acquired by the processor, or the user may enter “Floor Stock” or some location identification that allows items to be withdrawn or added that are not associated with a specific patient, and that withdrawal or addition can be associated with the account for that location. In some cases the user may be a person assigned to restock the system and may be adding, not withdrawing items, or may be a nurse returning an item that has been refused by a patient or was taken in error. The user now selects the medications and quantities of each medication that they wish to take or return for a patient, for Floor Stock or for the restock process.
The processor maintains a database with the list of medications or class groups of medications to which the user has access. The processor also knows the location of those medications in the cabinet and so also knows which locked doors may be unlocked for that user, and which doors must remains locked because it would give the user access to medications for which they are not authorized. The user selects one or more medications they wish to take, and the quantities of each. As they select each medication and the associated quantity, if access is allowed, they can proceed to the next medication. If not they will be told they have no access to that medication, but that they can proceed to select the next medication. When the selection list is complete, the user indicates completion to the processor, and the processor will activate the indicators to the first door, drawer and row/column indictor for the pocket for the first medication. The user opens the door, withdraws the drawer, identifies the pocket, and takes the medication, re-closing the drawer. The processor senses at a minimum the opening and closing of the drawer and will then activate the indicators for the next medication and the process is repeated until all the medications are taken.
It is necessary to guide the user to the right pocket or pocket. The exemplary method present here activates an indicator near the door that is unlocked and needs to be opened, and activates an indicator in the side of the cabinet indicating which drawer to access. These indicators may be one and the same. Within the drawer an indicator is activated from all array of indicators at the side of the drawer to identify which row contains the pocket, which contains the pharmaceutical or medical supply items that the user has requested to remove. Simultaneously an indicator within the inside of the front of the drawer is activated from an array of indicators on the inside of the front of the drawer, to identify which column contains the pocket, containing the pharmaceutical or medical supply items that the user has requested to remove. In this way the user can identify the single unique pocket at the intersection of the row and column, and can remove the requested item. To assist in the row identification, a second array of indicators can be placed at the opposite side of the drawer, one of which will be activated, to now identify both ends of the row that has the pocket containing the pharmaceutical or medical supply items that the user has requested to remove.
In some drawers there will be lids that are locked and it will be necessary for the processor to unlock these lids. In some drawers there are lids that are sensed by the processor when they are lifted, and the processor will note if the correct lid is lifted and record that information. The program will also alert the user, if an incorrect lid is lifted, and record that error. The alert can be a simple sound or text to speech or a pre-recorded message. Still other pockets may be open, without lids, and all pockets will be revealed when the drawer is opened, but each pocket may have an individual sensor that can detect when a hand or the fingers of a hand, enter that pocket, to take a medication. In all these cases, the processor has positive confirmation that a pocket has at least been accessed, even though it cannot be certain, in the case of multiple doses of the same medication in one pocket, how many items have actually been removed. In the case where there is just an open pocket and no sensor, the processor may only know that the pocket has been accessed by the opening and subsequent closing of the drawer and/or the entry of a confirmation by the user into the processor keyboard or touch screen, that the medication has been taken.
In another exemplary embodiment, in the case where the pockets are symmetrically arrayed in rows and columns, there is a locking mechanism for each individual pocket. There is an array of release mechanisms across the width of the inside of the drawer, each release mechanism able to lock or unlock all the lids in the row associated with that release mechanism. In addition there is an array of release mechanisms from front to back of the drawer, each release mechanism able to lock or unlock all the lids in the column associated with that release mechanism. With all release mechanism in locked position all pockets are locked. Activating one release mechanism into its release position across the width of the drawer, and one release mechanism into its release position from front to back, will unlock a single lid at the intersection of that row and column of those release mechanisms.
In an another exemplary embodiment, the sensors on an individual pocket send a signal that a pocket has been accessed. A mechanism for detecting the opening of lids of pockets containing pharmaceutical or medical supply items in a drawer is described in the case where the pockets are symmetrically arrayed in rows and columns. The lids are provided with arms extending into the body of the drawer, the end of the arm formed into a tab. An array of light sources are placed on the interior of one side of the drawer and corresponding light detectors are arrayed on the interior of the other side of the drawer, at least some of the light/detector pairs positioned so that the movement of a lid and associated tab as the lid is lifted, will break the beam of light between the source and receiver. It is preferable that the light source be infra-red to avoid interference from visible light. Similarly, an array of light sources is provided on the interior of the front side of the drawer and a corresponding set of light detectors is arrayed on the interior of the back side of the drawer, at least some of these light/detector pairs being positioned so that the movement of a lid and associated tab as the lid is lifted will break the beam of light between to source and receiver. In this way, the lifting of a specific lid will break in source-receiver pair in the cross direction, and one source-receiver pair in the front to back direction, allowing the processor to identify the single pocket at the X-Y intersection of that row and column.
In another exemplary embodiment there are modular locking drawers in the enclosure. These drawers are designed to contain unit doses of medications that are dispensed one at a time. The drawers are designed so that to advance to a second medication the drawer must be returned to it's fully closed position for each take. If, of course, a subsequent dose is not authorized to be taken, then the drawer is relocked. When the drawer is restocked there is a reset mechanism, that is operated by the restock technician, to reset this sequencing mechanism to the first full pocket.
In a further exemplary embodiment, a video camera is placed at the top of the cabinet pointing downward and another is placed in the center of the cabinet facing the user. When the user logs in, either using the processor keyboard or using one of many biometric identification devices that may be placed on the cabinet and connected to the processor, a process of video recording begins, recording both the face of the user and, utilizing the downward facing camera, any activity that the user may undertake as they withdraw medications from pockets in withdrawn drawers. At the completion of the user session, the video recordings are attached to the transaction record for that user in that session, and are stored in the processor.
This method for detecting access to a pocket does not work if there is no lid, so another method is described. A pair of metal plates in the wall of each individual pocket, form a capacitor. The change in dielectric and associated capacitance when a hand or the fingers of a hand enter the pocket, is detected using a sensitive bridge circuit. This bridge circuit is self balancing over time to accommodate the fact that the capacitance also varies due to the increase or decrease in dielectric constant in the gap between the capacitor plates created by the varying contents of the pocket itself. Since the circuit is primarily looking for an increase in dielectric when fingers are inserted, the bridge balancing circuit balances out decreases in capacitance rapidly, but remains sensitive to increases in capacitance. The detection of the dielectric change only occurs when the processor has recorded that a user has logged into the processor and that the medication retrieval process is not finished. In this way extraneous changes are ignored.
An exemplary dispensing unit is shown in
In
Within the drawer there are pockets. These pockets may be open matrix pockets, or lidded pockets, and the lids may be locking or non-locking, and may, or may not, be equipped with sensors to detect when they are opened. On the side of the cabinet there are arrays of indicators 10 to guide the user as to which compartment or drawer to open. These sensors may be inside the door, and only revealed when the door is opened, or may be outside the door and visible both with the door closed as well as opened, allowing the user to see which drawer is indicated during the time they are approaching the door to open it, and in fact guiding the user to the right door to open to access the required drawer. There are also modular drawers 33 that are not covered by doors, whose purpose is to dispense one dose of a single medication at a time. These drawers are designed so that the drawer must be fully closed and opened again for each dose taken, allowing the processor to count the doses taken. To provide convenient and fast access to electronics for repair, a pair of locks 12 and 13, allow a cover 11 to be removed. Removal of the cover gives access to mechanical or electronic release mechanisms concealed from tampering by the cover, which open other covers of the cabinet, or to release other hidden mechanisms and circuit boards from the front for service. A pair of locks is provided so that it might be the policy of the hospital that two people, each with separate and different keys, would be required to access the system which may contain narcotics. The locks are mounted on a simple cover, so that, should a key be lost or stolen, and the security of the system compromised, it is inexpensive to re-key the system.
The drawers 9, of which an open one 14 is shown in
For an eight by eight pocket array, there are sixty-four pockets and if an indicator is provided adjacent each pocket it would require sixty-four indicators whereas, the method and mechanism shown here requires sixteen indicators—or a maximum of twenty-four indicators, if the option to have indicators on both sides of the drawer is chosen. This means less cost. In addition, since the indicators are on the side of the drawer, this allows the possibility to have a standard (dense) array of indicators on the drawer and the drawer to be conveniently re-configured by inserting a new pocket liner in the standard drawer, with a different array of pockets. By entering the new configuration into the processor, the right selection of indicators will be used from the dense array, to line up with the pocket arrangement for the new liner. In this manner, just one drawer might be provided, with standard electronics for the indicators, reducing the cost for manufacture, and allowing the hospital to re-configure systems just by replacing the insert in a drawer, not having to replace the whole drawer mechanism.
In most cases however, the user needs access to all drawers, or, if a user is restricted, it is usually to a broad class such as narcotics, that can be kept in one group of drawers. Lower costs are also achieved by having just locking doors 28, over inexpensive molded plastic drawers 9. Although certain users may need to be restricted from accessing certain medications, this is usually to a broad class or group of medications like narcotics.
The camera 20 in
A typical user process is shown in
In step 162, the user may now select a patient from a list held within the processor, or enter a new or temporary patient ID or select “Floor Stock” in the case where a medication is to be taken for future use, or select “Remove Inventory” if the medication is being moved to an alternate secure location, or select “restock” if they are adding inventory to the cabinet. In step 163, the user will pre-select one or more medications they wish to remove, entering the quantity of each and reading any alert information provided by the system, whether it be patient specific, such as allergy alerts, or medication specific, such as route of administration. At this stage the user may also be asked to enter information, such as the reason for the dispense or return of the medication. The processor will also know, at step 164, whether the user is allowed access to each medication selected. If not, the processor will alert the user to that effect, but will allow the user to continue to select other medications to which the user maybe does have permission to access.
When the user has selected all the medications they wish to, and are allowed to, take, they indicate on the screen in step 165 that they now wish to take these preselected medications. The processor in step 166 will unlock the door 28, covering the drawer 9, containing the first medication that has been selected. In step 167 the processor indicates which door, 28, is unlocked by activating the appropriate indicator 10, and in step 168 indicates which drawer to withdraw from the cabinet. In this case the indicator 10 fulfills both purposes. In step 169 the user, having opened the unlocked door, opens the drawer, and in step 170 the Y-row, 13 and 17, and X-column 19 containing the pocket are indicated. If the pocket has a locking lid then that lid will be unlocked in step 171, and if a lid is present the user lifts the lid in step 172 and takes the medication. If the system detects access to the pocket, either by sensing the lifting of the lid or by sensing the presence of the users fingers in the pocket, then in step 175 a voice prompt is automatically played, using the sound file stored in the processor or using text to speech, reciting the name and dose of the medication. Additional information can also be included in the voice prompt including patient information such as allergy warning, and medication specific information such as route of delivery, or the need for a witness, and other useful information. If access to the medication is not automatically sensed, then the user needs to return to the screen in step 174 to indicate the medication has been taken, which then triggers the voice prompts and associated displays.
In step 176, if a countback is needed, the user can be prompted both by voice and on the screen, including reciting the current quantity the processor believes is in the pocket. When countback is completed, in step 177 the processor repeats the dispense process for the next medication, or, if this is the last medication selected, will prompt the user in step 178 to close all drawers and doors, and at this point any locking lids that have been opened will lock, and closed doors will be locked, step 179. Video recording will cease in step 180 and a record of the whole transaction sequence together with the video file will be stored in the local processor and also sent, as a periodic update to the central server. It is preferable that doors 28 are spring loaded so that if the doors are opened beyond ninety degrees, they stay open, but if they are returned to any position less than 90 degrees open, the door will swing shut, and that process will initiate re-latching and locking of the door. It would be unusual for a care-giver to not shut drawers and doors, since they are acutely aware of the importance of keeping medications secure, but if that were to happen, then, after a short period, the cabinet should give voice prompts that the doors and drawers need to be shut. Those prompts should be given until that action is complete. A short waiting period is desirable, to give time for a normal user to complete the task of closing the doors without being bothered by a prompt to take an action they know must be performed. In general, voice prompts should be brief, and preferably tailored to the user to give essential safety information, but not to annoy.
An important aspect of a dispensing system is accuracy. While a preferred method that has been described in the past is to only provide access to a single type of medication by placing each type in locked pockets and only opening the lid of the right pocket, this method is expensive. The invention proposed here, involves detecting when a pocket is accessed and providing a voice prompt which states the name and dose quantity of the medication being accessed. The voice prompt could be provided by a text-to-speech process, but, because of the risk of mispronunciation of hard to pronounce drug names by text-to-speech software, it would preferably be a sound file of the recorded voice of the pharmacist, made when the medication was originally entered into the database. The sound file would be transmitted along with all the other dug information needed, to each dispensing cabinet processor and become a part of the data base. Text-to-speech would be used in an emergency if the sound file was corrupted or missing. An important aspect is the ability for the user to clearly hear the spoken description of the medication, while not making the sound so loud that it disturbs other workers or patients. To this end the speaker 22, or speakers 22 and 24, shown in
Various mechanisms have been described in prior art for detecting the lifting of a lid using an adjacent sensor which is typically an optical transmitter and detector adjacent a move arm attached to the lid of the pocket, or is a magnet that attached to the moving arm attached to the pocket lid that triggers a hall effect device. For accuracy of dispensing it would also be desirable to detect when a persons fingers entered the opening of a non-lidded matrix pocket, allowing the voice prompt to recite the name and dose of the medication from the sound file previously stored in the database, or using text-to-speech from the character information stored in the database.
The system will start looking for changes when the user has logged in, has selected the medications and has opened the door covering the drawers to begin accessing medications. Since the system is guiding the user to the right location, the system knows which pocket they should be accessing. There are three sources of sudden change in capacitance. One is when the drawer is opened. In this case the bottom of the drawer above, and it's associated contents, are suddenly no longer above 110/111, causing a sudden drop in dielectric in the area above the capacitor formed by 110/111, and we wish to ignore this change. Insertion of fingers into the pocket causes a sudden increase in capacitance and we want to detect this and trigger the voice signal to recite the sound file and confirm the name and dose of the medication. Withdrawal of the fingers, probably accompanied by a medication gripped between those fingers, causes a drop in dielectric and hence a drop in capacitance, which we also want to ignore. Returning the drawer to the closed position causes an increase in capacitance, but by this time the system knows that the cycle is complete and will ignore the signal from that pocket caused by the drawer closing.
The signals received are shown in
At 151 the transaction is considered completed since a “take” in that pocket has been seen, and subsequent signals are ignored as the drawer closes. So, for example, as the drawer closes and the increased dielectric above increases the capacitance and impedance, 143, the associated increases in voltage 152 is ignored. In practice, the electronics of
With the lid 51 in closed position the light beams 61 and 67 are not interrupted, and this would be true for each pocket lid and X-Y light/detector pair combination in the drawer. However when the lid 51 starts to be opened, when it reaches position 55, shown by the dotted outline, the extension arm 53 has moved to a new position 56, and the tab 68 interrupts the light beam 61, and the tab 69 interrupts the light beam 67. Hence the light beams in the X and the Y direction, for just that position, are both interrupted, indicating that the lid has been lifted. No indication is given as to whether the lid is being opened or closed, but our interest is only in knowing at that time if the pocket is being accessed. The light interruption need not necessarily be simultaneous, but the electronics should be set up to such that, given say the X coordinate beam is interrupted first, a corresponding signal from a Y coordinate detector is received within a short period of time, which would be well under a second.
The normal locked position for a Y-direction bar is vertical as shown by bar 98, and for an X-direction bar, is flat as shown by bar 75. Consequently an extension arm (for a pocket not shown) at position 86 in
Both the X and Y bars must be in the “open” position for the arm to be free. For example, for pocket 70 and arm 72 in
This methodology provides economy. For an eight by eight matrix of pockets, you need sixteen rotary solenoids with this X-Y method, whereas, individual solenoids for each pocket would require sixty-four solenoids.
At some point the drawer needs to be restocked, either because it is empty or because it is the scheduled time to re-fill what has been taken. The restock technician enters their identification into the processor and selects the restock function at which point the drawers and doors on the cabinet, to which the technician has access, unlock. The restocking an shuttle reset process is performed as shown in
There are many ways to implement the method of requiring a drawer to be closed in order to advance the opening position by one, accompanied by a mechanism to reset the drawer after restocking. One embodiment is shown in
The lower serrated plate, 261 slides in the plane of the side of the draw, along grooves 265 and 259, held in position by pins 263 and 257. The serrated lower plate 261 is held to its left most position at the point 254, by a leaf spring 269 on the inside of the door 205 which is normally locked by lock 209. At the back of the drawer a sensing device 201 senses when the drawer has been fully closed. This sensor could be an optical sensor or a Hall effect device or a mechanical micro-switch. There is also the option to latch the drawer. A hinged pawl 271 operates in such a way that if the drawer closes and the latch 273 is in the upward position, the pawl is shaped so that it slides over the latch and falls into the latch socket and locks. The drawer is unlocked when the solenoid 275 is operated, pulling the latch 273 down from the hook on the pawl 271. There are many other electromechanical latching arrangements available to those skilled in the art.
Initially the shuttle is in position 253 in the groove 246 between upper serrated plate 243 and the lower serrated plate 261. Referring now to
We now address the issue of how to get the shuttle back when the drawer is to be restocked with items. The drawer may not be fully empty at the time of restocking. Referring to
In
If the restock technician does not have enough product to completely re-fill the drawer, they will fill from the back. This might leave, for example, two empty pockets at the front, and the first medication in pocket 3. During the restock process the processor will keep the drawer unlocked. Consequently, starting from the restocked position of
Other mechanisms can be created to implement the method of requiring a drawer to be closed in order to advance the opening position by one, accompanied by a mechanism to reset the drawer after restocking. One system would utilize a belt and another would utilize a miniature form of bicycle chain.
This application claims benefit of priority to U.S. Provisional Application No. 60/866,081 filed Jan. 22, 2007 which is incorporated by reference herewith in its entirety.
| Number | Name | Date | Kind |
|---|---|---|---|
| 4429274 | Hamblen | Jan 1984 | A |
| 4518208 | Marder | May 1985 | A |
| 4635053 | Banks et al. | Jan 1987 | A |
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| Number | Date | Country |
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