US20110006073A1 - Methods and Apparatus for Dispensing Solid Pharmaceutical Articles - Google Patents

Abstract

A method is provided for dispensing solid pharmaceutical articles using an apparatus including a housing and a sensor system, the housing defining a dispensing passage having a dispensing inlet and a dispensing outlet downstream of the dispensing inlet, the sensor system including first and second sensors spaced apart along the dispensing channel such that the second sensor is located downstream of the first sensor. The method includes: forcing at least one article along a path through the dispensing passage; generating detection signals using the first and second sensors responsive to articles passing through the dispensing channel; and using the detection signals from the first and second sensors to monitor dispensing performance of the apparatus.

Description

RELATED APPLICATION(S)
• The present application is a continuation patent application of and claims priority from U.S. patent application Ser. No. 11/834,936, filed Aug. 7, 2007, which claims the benefit of U.S. Provisional Patent Application No. 60/938,835, filed May 18, 2007, the disclosures of which are hereby incorporated herein by reference in their entireties.
FIELD OF THE INVENTION
• The present invention is directed generally to the dispensing of solid pharmaceutical articles and, more specifically, is directed to the automated dispensing of solid pharmaceutical articles.
BACKGROUND OF THE INVENTION
• Pharmacy generally began with the compounding of medicines which entailed the actual mixing and preparing of medications. Heretofore, pharmacy has been, to a great extent, a profession of dispensing, that is, the pouring, counting, and labeling of a prescription, and subsequently transferring the dispensed medication to the patient. Because of the repetitiveness of many of the pharmacist's tasks, automation of these tasks has been desirable.
• Some attempts have been made to automate the pharmacy environment. For example, U.S. Pat. No. 6,971,541 to Williams et al. describes an automated system for dispensing pharmaceuticals using dispensing bins. Each dispensing bin includes a hopper in which tablets are stored and a dispensing channel fluidly connecting the hopper to a dispensing outlet. Forward and reverse air flows are used to selectively convey the tablets through the dispensing channel in each of a dispensing direction (toward the outlet) and a reverse direction (toward the hopper). A counting sensor is positioned proximate the outlet of the dispensing channel and used to detect tablets passing the sensor in order to maintain a count of the tablets dispensed.
SUMMARY OF THE INVENTION
• According to some embodiments of the present invention, a method is provided for dispensing solid pharmaceutical articles using an apparatus including a housing and a sensor system, the housing defining a dispensing passage having a dispensing inlet and a dispensing outlet downstream of the dispensing inlet, the sensor system including first and second sensors spaced apart along the dispensing channel such that the second sensor is located downstream of the first sensor. The method includes: forcing at least one article along a path through the dispensing passage; generating detection signals using the first and second sensors responsive to articles passing through the dispensing channel; and using the detection signals from the first and second sensors to monitor dispensing performance of the apparatus.
• According to some embodiments of the present invention, an apparatus for dispensing solid pharmaceutical articles includes a housing, a drive mechanism and a sensor system. The housing defines a dispensing passage having a dispensing inlet and a dispensing outlet downstream of the dispensing inlet. The drive mechanism serves to force the articles along a path through the dispensing passage between the dispensing inlet and the dispensing outlet. The sensor system includes first and second sensors operative to detect articles passing through the dispensing passage and a controller to receive and use detection signals from the first and second sensors to monitor dispensing performance of the apparatus. The first and second sensors are spaced apart along the dispensing channel such that the second sensor is located downstream of the first sensor.
• According to some embodiments of the present invention, a method is provided for dispensing solid pharmaceutical articles using an apparatus including a housing and a sensor system, the housing defining a dispensing channel having a dispensing inlet and a dispensing outlet downstream of the dispensing inlet, the sensor system including first and second sensors positioned along the dispensing channel. The method includes: forcing at least one article along a path through the dispensing channel; generating detection signals using the first and second sensors responsive to articles passing through the dispensing channel; and comparing the detection signals from the first and second sensors to determine whether a dispensing fault condition has occurred.
• According to some embodiments of the present invention, a method is provided for dispensing solid pharmaceutical articles using an apparatus including a housing and a sensor system, the housing defining a dispensing channel having a dispensing inlet and a dispensing outlet downstream of the dispensing inlet, the sensor system including at least one sensor positioned along the dispensing channel. The method includes: forcing at least one article along a path through the dispensing channel; generating detection signals using the at least one sensor responsive to articles passing through the dispensing channel; and using a duration of at least one of the detection signals from the at least one sensor to determine whether a dispensing fault condition has occurred.
• Further features, advantages and details of the present invention will be appreciated by those of ordinary skill in the art from a reading of the figures and the detailed description of the preferred embodiments that follow, such description being merely illustrative of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a flow chart illustrating methods according to embodiments of the present invention.
• FIG. 2 is a perspective view of a pharmaceutical tablet dispensing system including a sensor system according to embodiments of the present invention.
• FIG. 3 is a cutaway view of the tablet dispensing system ofFIG. 2 illustrating a container dispensing station, a labeling carrier, a dispensing carrier, and a closure dispensing station thereof.
• FIG. 4 is a front perspective view of a dispensing bin according to embodiments of the present invention.
• FIG. 5 is a cross-sectional view of the bin ofFIG. 4 filled with tablets at rest.
• FIG. 6 is a cross-sectional view of the bin ofFIG. 4 wherein tablets contained therein are being agitated and dispensed in a forward or dispensing direction.
• FIG. 7 is a cross-sectional view of the bin ofFIG. 4 wherein a tablet is being returned to a hopper of the bin in a reverse direction.
• FIG. 8 is a block diagram representing a sensor system and control valves of the pharmaceutical dispensing system ofFIG. 1.
• FIGS. 9-13 are schematic diagrams representing detection pulse signals of an entrance sensor and an exit sensor of the sensor system ofFIG. 8 over time.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
• The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments of the invention are shown. In the drawings, the relative sizes of regions or features may be exaggerated for clarity. This invention may, however, 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 be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
• It will be understood that when an element is referred to as being “coupled” or “connected” to another element, it can be directly coupled or connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly coupled” or “directly connected” to another element, there are no intervening elements present. Like numbers refer to like elements throughout.
• In addition, spatially relative terms, such as “under”, “below”, “lower”, “over”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “under” or “beneath” other elements or features would then be oriented “over” the other elements or features. Thus, the exemplary term “under” can encompass both an orientation of over and under. The device maybe otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
• 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 singular forms “a”, “an” and “the” are intended to include the plural forms as well, 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, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein the expression “and/or” includes any and all combinations of one or more of the associated listed items.
• Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of 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 will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
• In accordance with embodiments of the present invention apparatus and methods are provided for dispensing solid pharmaceutical articles. In particular, such methods and apparatus may be used to dispense pharmaceuticals. With reference toFIG. 1, methods according to embodiments of the present invention may be executed using an apparatus including a housing, a flow generator, and a sensor system, the housing defining a dispensing channel having a dispensing inlet and a dispensing outlet downstream of the dispensing inlet, the sensor system including first and second sensors spaced apart along the dispensing channel such that the second sensor is located downstream of the first sensor. At least one drive gas flow is generated using the flow generator to force at least one article along a path through the dispensing channel (Block20). The dispensing channel may or may not be fully enclosed. Responsive to articles passing through the dispensing channel, detection signals are generated using the first and second sensors (Block22). The detection signals from the first and second sensors are used to monitor dispensing performance of the apparatus (Block24). According to some embodiments, the articles are pharmaceutical tablets.
• A dispensing system according to embodiments of the present invention and that can carry out the foregoing methods is illustrated inFIGS. 2-8 and designated broadly therein at40 (FIGS. 2 and 3). The dispensingsystem40 includes a sensor system102 (FIG. 8) according to embodiments of the present invention. Thesystem40 includes asupport frame44 for the mounting of its various components. Those skilled in this art will recognize that theframe44 illustrated herein is exemplary and can take many configurations that would be suitable for use with the present invention. Theframe44 provides a strong, rigid foundation to which other components can be attached at desired locations, and other frame forms able to serve this purpose may also be acceptable for use with this invention.
• Thesystem40 generally includes as operative stations a controller (represented herein by a graphical user interface42), acontainer dispensing station58, alabeling station60, atablet dispensing station62, aclosure dispensing station64, and an offloadingstation66. In the illustrated embodiment, containers, tablets and closures are moved between these stations with a dispensingcarrier70; however, in some embodiments, multiple carriers are employed. The dispensingcarrier70 has the capability of moving the container to designated locations within thecavity45 of theframe44. Except as discussed herein with regard to the dispensingstation62, each of the operative stations and the conveying devices may be of any suitable construction such as those described in detail in U.S. Pat. No. 6,971,541 to Williams et al. and/or U.S. Patent Publication No. US-2006-0241807-A1, the disclosures of which are hereby incorporated herein in their entireties.
• Thecontroller42 controls the operation of the remainder of thesystem40. In some embodiments, thecontroller42 will be operatively connected with an external device, such as a personal or mainframe computer, that provides input information regarding prescriptions. In other embodiments, thecontroller42 may be a stand-alone computer that directly receives manual input from a pharmacist or other operator. An exemplary controller is a conventional microprocessor-based personal computer.
• In operation, thecontroller42 signals thecontainer dispensing station58 that a container of a specified size is desired. In response, thecontainer dispensing station58 delivers a container for retrieval by thecarrier70. From thecontainer dispensing station58, the container is moved to thelabeling station60 by thecarrier70. Thelabeling station60 includes a printer that is controlled by thecontroller42. The printer prints and presents an adhesive label that is affixed to the container.
• Filling of labeled containers with tablets is carried out by thetablet dispensing station62. Thetablet dispensing station62 comprises a plurality of tablet dispensing bin assemblies or bins100 (described in more detail below), each of which holds a bulk supply of individual tablets (typically thebins100 will hold different tablets). Referring toFIGS. 4 and 5, the dispensingbins100, which may be substantially identical in size and configuration, are organized in an array mounted on the rails of theframe44. Each dispensingbin100 has a dispensing passage orchannel120 with anoutlet124 that faces generally in the same direction, to create an access region for the dispensingcarrier70. The identity of the tablets in each bin is known by thecontroller42, which can direct the dispensingcarrier70 to transport the container to theproper bin100 to fill the particular prescription. In some embodiments, thebins100 may be labeled with a bar code or other indicia to allow the dispensingcarrier70 to confirm that it has arrived at theproper bin100.
• The dispensingbins100 are configured to singulate, count, and dispense the tablets contained therein, with the operation of thebins100 and the counting of the tablets being controlled by thecontroller42. Some embodiments may employ thecontroller42 as the device which monitors the locations and contents of thebins100; others may employ thecontroller42 to monitor the locations of the bins, with thebins100 including indicia (such as a bar code or electronic transmitter) to identify the contents to thecontroller42. In still other embodiments, thebins100 may generate and provide location and content information to thecontroller42, with the result that thebins100 may be moved to different positions on theframe42 without the need for manual modification of the controller42 (i.e., thebins100 will update thecontroller42 automatically).
• Any of a number of dispensing units that singulate and count discrete objects may be employed if suitably modified to include the inventive aspects disclosed herein. In particular, dispensing units that rely upon targeted air flow and a singulating nozzle assembly may be used, such as the devices described in U.S. Pat. No. 6,631,826 to Pollard et al. and/or U.S. Patent Publication No. US-2006-0241807-A1, each of which is hereby incorporated herein by reference in its entirety. Bins of this variety may also include additional features, such as those described below.
• After the container is desirably filled by thetablet dispensing station62, the dispensingcarrier70 moves the filled container to theclosure dispensing station64.
• Theclosure dispensing station64 may house a bulk supply of closures and dispense and secure them onto a filled container. The dispensingcarrier70 then moves to the closed container, grasps it, and moves it to the offloadingstation66.
• Turning to thebins100 in more detail, anexemplary bin100 is shown in more detail inFIGS. 4-8. Thebin100 includes ahousing110 having ahopper portion112 and anozzle114.
• Referring toFIG. 6, thehopper portion112 defines ahopper chamber112A that can be filled with tablets T. Alower screen130A is provided in the floor of thehopper portion112 and anupper screen130B is provided in the ceiling of thehopper portion112. As discussed below, air or other suitable gas can be flowed through thescreens130A,130B and thechamber112A to agitate the tablets T contained therein.
• With reference toFIG. 5, thenozzle114 defines a dispensingchannel120 through which the tablets T can be dispensed one at a time. The dispensingchannel120 has aninlet122 adjacent and fluidly connecting thechannel120 to thechamber112A. The dispensingchannel120 has anoutlet124 downstream from and opposite theinlet122 and through which tablets may exit thenozzle114 to be dispensed into the container C (FIG. 7).
• Thehousing110 further includes alow pressure port132 and a high pressure nozzle134 (FIGS. 4 and 6). Adoor132A is provided to selectively open and close theport132 by operation of an associatedsolenoid132B.
• With continued reference toFIG. 5, aforward jet passage140 is fluidly connected to thehigh pressure nozzle134 and terminates in aforward jet aperture140A at the dispensingchannel120. Aforward control valve142 is operable to control airflow to thejet aperture140A. A rearward or reverse jet passage144 is also fluidly connected to thehigh pressure nozzle134 and terminates in a rearward orreverse jet aperture144A at the dispensingchannel120. Areverse control valve146 is operable to control airflow to thejet aperture144A.
• According to some embodiments and as described in U.S. Patent Publication No. US-2006-0241807-A1, thetablet dispensing station62 includes alow pressure manifold74 fluidly connected to a low pressure source such as a vacuum motor (not shown), which provides low level (i.e., about 2 psi) suction to draw air FA through (in succession) thescreen130A, thechamber112A, thescreen130B and theport132 to agitate tablets within thehopper chamber112A (FIG. 6). Also, a high pressure (i.e., about 30 psi)conduit72 fluidly connected to a high pressure source (not shown) is fluidly connected to thehigh pressure nozzle134 to supply high pressure air to thejet apertures140A,144A. Further, aconnector circuit board77 is mounted horizontally below themanifold74. Thecircuit board77 or other electrical connector provides an electrical connection between thecontroller42 and a bin-controlling circuit board78 (or other electronic component) of thebin100 for power and data signals to/from thecontroller42.
• Thesensor system102 includes a front orexit sensor80 and a rear orentrance sensor84 positioned along thechannel120. Theexit sensor80 is located downstream (i.e., in the forward or dispensing direction of the tablet flow path through the dispensing channel120) from theentrance sensor84 along the dispensingchannel120. Theexit sensor80 is mounted in thenozzle114 proximate theoutlet124 and distal from theinlet122 and faces thechannel120. Theentrance sensor84 is mounted in thenozzle114 proximate theinlet122 and distal from theoutlet124 and also faces thechannel120. Thesensors80,84 are tablet detecting sensors and are operably connected to associated sensor receiver/processor electronics. Thesensors80,84 may be electrically connected to an associated controller bylead wires80A,84A. According to some embodiments, the associated controller is or includes thecontroller42 and/or thecircuit board78. As further discussed below, thesensors80,84 are configured and positioned to detect the tablets T as they pass through the dispensingchannel120. Thesensors80,84 and the associatedcontroller42 together comprise asensor system102 operative to monitor flow of tablets T through thechannel120 and, thereby, dispensing performance of thebin100. According to some embodiments, thecontroller42 uses detection signals from at least one of thesensors80,84 to count the dispensed tablets. According to some embodiments, at least theexit sensor80 is used for this purpose. In some cases, the sensor system operates thevalves142,146 or other devices in response to identified or determined conditions or performance in dispensing. While twosensors80,84 are described herein, apparatus and methods according to embodiments of the present invention may use sensor systems that use more than two tablet detection sensors along the flow path.
• According to some embodiments, thesensors80,84 are photoelectric sensors. According to some embodiments, thesensors80,84 are infrared (IR) sensors. According to some embodiments, photoemitters82 and86 (e.g., IR emitters) are mounted in the nozzle opposite thesensors80 and84, respectively, to emit photoemissions toward therespective sensors80,84 across thechannel120. Thephotoemitters82,86 may be operatively connected to thecontroller42 orcircuit board78 bywires82A,86A. According to some embodiments, all or some of thecomponents80,84 and82,86 may include both a photoemitter and a photodetector, whereby thecomponents82,86 may also serve as sensors. For the purpose of explanation, the illustrated embodiment will be described with only thecomponents80,84 being sensors (i.e., thesensors80,84 receive photoemissions from thephotoemitters82,86). Other types of sensors may be employed as well. Other suitable types of sensors may include, for example, UV, RF, capacitive and EMF sensors.
• Theexit sensor80 and theentrance sensor84 are spaced apart along the channel120 a distance D (FIG. 5). The preferred or minimum distance D may be determined by the type of sensor and/or other parameters or arrangements or physical limitations of the components. According to some embodiments, the distance D should be large enough to prevent cross-talk between the components and to provide two distinct signals from therespective sensors80,84. The minimum distance D may also be limited or determined by the time needed to prevent an extra pill from exiting the channel120 (i.e., once the requested count is reached, the distance D should allow enough time to stop an extra pill from exiting).
• According to some embodiments, theentrance sensor84 is positioned along thechannel120 at, in or immediately adjacent theinlet122. According to some embodiments, theexit sensor80 is positioned along thechannel120 at, in or immediately adjacent theoutlet124.
• Exemplary operation of the dispensingsystem40 will now be described. Thebin100 is filled with tablets T to be dispensed. The tablets T may initially be at rest as shown inFIG. 5. At this time, thevalves142,146 are closed so that no gas flow is provided through thejet outlets140A,144A.
• To fill the container C, the dispensingcarrier70, directed by thecontroller42, moves the container C to the exit port of the selected dispensingbin100. Thecontroller42 signals thesolenoid132B to open thedoor132A. This opening of thedoor132A draws low pressure air up through thehopper chamber112A to the manifold74, thereby agitating the tablets T contained in the hopper chamber112B.
• Once agitation has commenced, thecontroller42 signals theforward valve142 to open (while thereverse valve146 remains closed). The openedvalve142 permits the pressurized gas from thegas source72 to flow through thepassage140 and out through the forwarddrive jet outlet140A. The pressurized flow from thejet outlet140A creates a high velocity gas jet that generates suction that causes a forward flow FF of high pressure, high velocity air to be drawn outwardly through the dispensingchannel120 in a dispensing direction (FIG. 6). Tablets T are oriented into a preferred orientation by the shape of theinlet122 to the dispensingchannel120 and dispensed into the container C through the dispensingchannel120 and theoutlet124 under the force of the forward flow FF.
• Once dispensing is complete (i.e., a predetermined number of tablets have been counted by thecontroller42 as dispensed), thecontroller42 activates theforward valve142 to close and thereverse valve146 to open. The openedvalve146 permits the pressurized gas from thegas source72 to flow through the passage144 and out through the reversedrive jet outlet144A. The pressurized flow from thejet outlet144A creates a high velocity gas jet that generates suction that causes a reverse (i.e., rearward) flow FR of high pressure air to be drawn inwardly through the dispensingchannel120 toward thechamber112A in a reverse or return direction. In this manner, the airflow is reversed and any tablets T remaining in thechannel120 are returned to thechamber112A under the force of the reverse flow (FIG. 7).
• While, in the foregoing description, thecontroller42 controls thevalves142,146, thevalves142,146 may alternatively be controlled by a local controller unique to eachbin100. Thebin100 can be filled or replenished with tablets via access from a pivoting door127 (FIG. 5) located at the upper rear portion of thebin100, for example. As disclosed in U.S. Patent Publication No. US-2006-0241807-A1, thebin100 may include components that permit the entry to the dispensingchannel120 to be adjusted in size to complement the size and configuration of the tablet to be dispensed.
• During the dispensing phase (i.e., when the forward flow FF is being generated), a tablet jam may occur. A tablet jam is a condition wherein one or more tablets are caught up in thebin100 such that tablets T will not feed into or through the dispensingchannel120 under the force of the forward flow FF. A jam is indicated if theentrance sensor84 has not detected a pill within a specified time period (e.g., one second). When a tablet jam is identified by thecontroller42, thecontroller42 will close theforward valve142 and open thereverse valve146 to generate the reverse flow FR to clear a perceived tablet jam. This action of thecontroller42 may be referred to as issuing a “jam clear”.
• According to some embodiments, thecontroller42 will execute a calibration procedure between dispensing sessions (i.e., between the end of a forward flow FF and the initiation of the next forward flow FF) in order to calibrate thesensors80,84. According to some embodiments, the calibration procedure includes opening thereverse valve146 to generate the reverse flow FR while calibrating thesensors80,84. This may ensure that no tablets or tablet fragments occlude thesensors80,84 and thereby corrupt the calibration. Thecontroller42 may conduct the calibration procedure automatically and/or shortly or immediately after a dispensing session and thebin100 may remain idle (i.e., with neither a forward flow FF nor a reverse flow FR being generated) during an idle period between the end of the calibration reverse flow FR and the initiation of the next dispensing session.
• Typically, an operator will request that a desired number of tablets be dispensed (“the requested count”). Thesensors80,84 detect the tablets T as they pass through predetermined points in the dispensingchannel120, as discussed in more detail below. Thecontroller42 uses the detection signals from thesensors80,84 to monitor and maintain a registered count of the tablets T dispensed (“the system count”). When the system count matches the requested count, thecontroller42 will deem the dispensing complete and cease dispensing of the tablets T. If the controller miscounts the tablets actually dispensed, there may be a mismatch between the requested count and the final actual count.
• In practice and in the absence of the apparatus and methods of the present invention, the foregoing processes may suffer from various fault conditions or other dispensing concerns. In prior art systems of the type employing only a single counting sensor or set of counting sensors at one location along the dispensing channel (e.g., at the exit end) to detect tablets in the dispensing channel (hereinafter referred to as “prior art single sensor systems”), these fault conditions may result in inaccurate counts such as counting a tablet that is not dispensed, failing to count a tablet that is dispensed, or failing to recognize a partial tablet.
• The foregoing concerns may be addressed by thesensor system102 of thebin100 and methods in accordance with embodiments of the present invention. According to some embodiments, theentrance sensor84 proximate theinlet122 of thechannel120 performs the duty of detecting tablet jams and theexit sensor80 proximate the exit oroutlet124 performs the duty of counting the dispensed tablets. By separating these two functions, the exit sensor80 (i.e., the count sensor) can be guarded by the entrance sensor84 (i.e., the jam sensor) to ensure that no tablets are in the dispensingchannel120 during a jam clear. The twosensors80,84 can also be cooperatively employed to detect and identify other modes of failure.
• Such failure modes are called “exception events” and arise when the sensor output does not follow the expected pulse width and travel times for a singulated pill in standard operation of thebin100. Some exception events and corresponding operations of thebin100 that may be encountered will be described hereinbelow. However, it will be appreciated that this description is not exhaustive of the advantageous uses of the apparatus in accordance with embodiments of the present invention.
• In some cases, two or more tablets T may be disposed or “preloaded” in thechannel120 in or closely adjacent theinlet122 prior to actuation of theforward valve142 to generate the forward flow FF. This condition may be referred to as a “preload dispensing fault condition”. A preload dispensing fault condition may occur when tablets in the dispensingchannel120 are not fully returned to thehopper chamber112A by a reverse flow or “jam clear” intended to clear the dispensingchannel120, for example. A preload dispensing fault condition may also occur when tablets unintentionally migrate into the dispensingchannel120 from the hopper. For example, during the idle period between a jam clear or other reverse flow FR and the initiation of the next forward flow FF, tablets may slide or vibrate out of thehopper chamber112A and into theinlet122 or the dispensingchannel120. In prior art single sensor systems, upon initiation of the forward flow FF, the two or more preloaded tablets may travel down thechannel120 in contact with or very closely adjacent one another so that the two or more tablets pass the counting sensor (which is typically located proximate the dispensing outlet) together. The counting sensor may generate only a single, extra long detection pulse for the two or more tablets rather than two or more discrete pulses that are required to register a count of two or more tablets. As a result, two or more tablets are dispensed through the dispensing outlet but the system count of dispensed tablets is only incremented by one tablet.
• In accordance with embodiments of the present invention, a preload dispensing fault condition can be identified and corrected by monitoring theentrance sensor84. More particularly, theentrance sensor84 is configured and located with respect to the dispensingchannel120 and theinlet122 such that, in the case of a preload dispensing fault condition, one or more of the tablets will occlude theentrance sensor84. When this condition occurs prior to initiation of the forward flow FE, theentrance sensor84 will provide a detection signal to thecontroller42 indicating that the one or more tablets is/are at theentrance sensor84. In response to the detection signal from theentrance sensor84 prior to initiating the forward flow FF, thecontroller42 identifies the existence of the preload dispensing fault condition. Further in response, thecontroller42 will thereafter open thereverse valve146 to generate the reverse flow FR to force any tablets T lingering in thechannel120 back into thehopper chamber112A. In this manner, thechannel120 is cleared and the preload dispensing fault condition is removed prior to the onset of tablet dispensing.
• A preload dispensing fault may also occur wherein the preloaded tablet or tablets are disposed in the dispensingchannel120 between theentrance sensor84 and theexit sensor80 prior to actuation of theforward valve142 to generate the forward flow FF. The preloaded tablets may not occlude theentrance sensor84. According to some embodiments of the present invention, preload dispensing fault conditions of this type are identified and corrected by continuously monitoring theentrance sensor84 even when thebin100 is idle. According to some embodiments, theentrance sensor84 is continuously monitored at least from the end of the actuation of the reverse flow FR during calibration as discussed above to the start of the forward flow FF to begin a dispensing session (i.e., the idle period). According to some embodiments, theentrance sensor84 is also continuously monitored throughout the calibration period. According to some embodiments, theentrance sensor84 is continuously monitored at all times. If a tablet is detected by theentrance sensor84 during the idle period, thecontroller42 identifies the existence of a preload dispensing fault condition. Thecontroller42 may respond to the identified fault condition by generating the reverse flow FR to force any tablets lingering in thechannel120 back into thehopper chamber112A. In this manner, thechannel120 is cleared and the preload dispensing fault condition is removed prior to the onset of tablet dispensing.
• Thesensor system102 may employ the following method to address a “tandem dispensing fault condition.” With reference toFIG. 9, when a tandem dispensing fault condition is present, thecontroller42 may generate the forward flow FF to dispense the tablets as discussed above with regard to the prior art single sensor systems. This may occur if theentrance sensor84 is not relied upon to sense preloaded tablets or the tandem condition is not detectable because the configuration/locations of the tablets do not cause thesensor84 to immediately start with a tablet detection. The outputs of thesensors80,84 are monitored by thecontroller42 and compared. Each of the two tablets passes theentrance sensor84 in immediate succession, which causes the entrance sensor to generate a single pulse P2 as represented by the signal pulse graph A) ofFIG. 9. The signal pulse P2 has a duration that is larger than that of a prescribed or average reference duration for a single tablet passing thesensor84 during dispensing. Thereafter, the two tablets pass theexit sensor80 in immediate succession, which causes theexit sensor80 to generate one continuous, long duration signal pulse P4 as represented by the detector pulse graph B) ofFIG. 9. The signal pulse P4 has a duration that is larger than that of a prescribed or average reference duration for a single tablet passing thesensor80 during dispensing. Thecontroller42 compares the durations of the signals P2, P4 with the corresponding expected or average signal pulse durations and also compares the time TBP between the pulses P2, P4 with the expected or average time between pulses for standard operation, and determines that a tandem dispensing fault condition has occurred. In response, thecontroller42 may increment the system dispensed count by an appropriate amount and/or alert an operator. The expected or average signal pulse durations for thesensors80,84 and the expected or average time between the pulses of thesensors80,84 may be determined using average entrance, exit and nozzle velocities determined as described below.
• In some cases, a first tablet T lingers in the dispensingchannel120 during dispensing so that a second tablet T catches up to and collides with the first tablet before the first tablet is detected or completely detected by a counting sensor. The second tablet travels down thechannel120 in contact with the first tablet so that the first and second tablets pass the counting sensor together, responsive to which the counting sensor generates a single, extended duration signal pulse. This condition may be referred to as a “collision dispensing fault condition”. In prior art single sensor systems, the single, extended duration signal pulse may simply be counted as a single tablet. As a result, two tablets are actually dispensed from the outlet but the system tablet dispense count is only incremented by one tablet.
• In accordance with embodiments of the present invention, a collision dispensing fault condition can be identified and corrected by monitoring theexit sensor80 and theentrance sensor84. More particularly, the outputs of theexit sensor80 and theentrance sensor84 are monitored by thecontroller42 and compared. In the case of a collision dispensing fault condition, each of the two tablets passes theentrance sensor84 in turn and with spacing between the tablets, which causes theentrance sensor84 to generate two discrete signal pulses P10, P12 in sequence over time, as represented by the signal pulse graph A) ofFIG. 10. These two pulses P10, P12 have a duration corresponding to a typical single tablet. Thereafter, the two tablets pass theexit sensor80 in immediate succession, which causes theexit sensor80 to generate one long duration signal pulse P14 as represented by the detector pulse graph B) ofFIG. 10. Thecontroller42 compares the signals P10, P12, P14 from thesensors80,84 and determines that a collision dispensing fault condition has occurred. In response, thecontroller42 may increment the system dispensed count total by the appropriate amount (in this example, two). Alternatively, in response, thecontroller42 may issue an alert to an operator or the like indicating that a tablet may have been dispensed but not counted.
• In some cases in prior art single sensor systems, a tablet that has been previously detected by a count sensor and counted by the sensor as dispensed is drawn back into or through the dispensing channel by a reverse drive gas flow FR (i.e., the tablet is aspirated back into the dispensing channel or hopper chamber). This occurrence may be referred to as an “aspiration dispensing fault condition”. In prior art single sensor systems, the system count will exceed the actual number of dispensed tablets.
• In accordance with embodiments of the present invention, an aspiration dispensing fault condition can be identified and corrected by monitoring theexit sensor80 and theentrance sensor84, and the direction of drive gas flow. More particularly, the outputs of theexit sensor80 and theentrance sensor84 are monitored by thecontroller42 and compared. Each signal pulse from theexit sensor80 will be accounted for if preceded by a corresponding signal pulse from theentrance sensor84. Under normal (nonfault) conditions, each tablet drawn from thehopper112A passes theentrance sensor84 and then theexit sensor80 and generates corresponding signal pulses in sequence. In the case of an aspiration dispensing fault condition, a tablet previously counted as dispensed passes theexit sensor80, which causes theexit sensor80 to generate a signal pulse P20 as represented by the detector pulse graph B) ofFIG. 11. Thereafter, the tablet passes theentrance sensor84, which causes theentrance sensor84 to generate a signal pulse P22 as represented by the detector pulse graph A) ofFIG. 11. Thecontroller42 determines that the drive gas flow was in the reverse direction when the pulses P20, P22 were generated and compares the signals P20, P22 from thesensors80,84. The controller determines that the exit signal pulse P20 did not have a corresponding preceding entrance sensor pulse and the exit sensor detection pulse P20 was triggered or generated prior to the entrance sensor detection pulse P22. From this, thecontroller42 determines that an aspiration dispensing fault condition has occurred. In response, thecontroller42 may decrement the system dispensing count total by one. Alternatively, in response, thecontroller42 may issue an alert to an operator indicating that a tablet may have been counted and thereafter aspirated.
• In some cases in prior art single sensor systems, jams are detected using the single sensor, which is typically positioned proximate the outlet of the dispensing channel. If, when the forward drive gas flow is being generated, some prescribed length of time (e.g., 1.0 second) passes without a tablet being detected by the single sensor, the system will issue a reverse drive gas flow in order to clear an upstream jam in the dispensing channel (i.e., the presumed cause of the failure to detect a tablet at the sensor). However, because of the length of time required for a tablet to travel from the entrance, the reverse drive gas jet flow may be initiated while a tablet is in fact en route to the exit count sensor such that the tablet occludes the count sensor, reverses direction in the dispensing channel, and returns back to the hopper chamber. This occurrence may be referred to as a “tablet reversal dispensing fault condition”. In prior art single sensor systems, the tablet may be counted as dispensed and the reversal may not be registered so that the system count is increased over the actual number of tablets dispensed by one. Moreover, in some cases, the reversed tablet may be counted twice (once when passing the count sensor in the dispensing direction and once when passing the count sensor in the reverse direction).
• In accordance with embodiments of the present invention, a tablet reversal dispensing fault condition is prevented by triggering the reverse drive gas flow (jam clear) off of theentrance sensor84 instead of the countingsensor80. More particularly, thecontroller42 monitors theentrance sensor84. If a tablet is not detected by theentrance sensor84 within a prescribed length of time (wait time) while the forward drive gas flow (i.e., the dispensing flow) is being generated, thecontroller42 will identify a tablet jam condition. Responsive to the tablet jam condition, thecontroller42 will issue a jam clear (i.e., open thereverse valve146 to generate a burst or sustained reverse flow FR). In this manner, theentrance sensor84 “guards” theexit sensor80.
• Thesensor system102 may additionally or alternatively employ the following method to identify and correct a tablet reversal dispensing fault condition by monitoring theexit sensor80, theentrance sensor84, and the direction of drive gas flow. The outputs of theexit sensor80 and theentrance sensor84 are monitored by thecontroller42 and compared. In the case of a tablet reversal dispensing fault condition, a tablet passes the entrance sensor84 (which causes theentrance sensor84 to generate a typical duration signal pulse P30 as represented by the detector pulse graph A) ofFIG. 12), thereafter passes the exit sensor80 (which causes theexit sensor80 to generate an extra long duration signal pulse (or two signal pulses as shown by the dotted line) P32 as represented by the detector pulse graph B) ofFIG. 12), and thereafter again passes the entrance sensor84 (which causes theentrance sensor84 to generate a typical duration signal pulse P34). Thecontroller42 determines that the drive gas flow was in the forward direction during the pulse P30 and in the reverse direction during the pulse P34, compares the signals P30, P32, P34 from thesensors80,84, and determines that a tablet reversal dispensing fault condition has occurred. In response, thecontroller42 may decrement the dispensing count total by one. Alternatively, in response, thecontroller42 may issue an alert to an operator indicating that a tablet may have been counted and thereafter reversed.
• While events such as those described above may be characterized by specific sequences of events, thesensor system102 may also derive information about the events themselves or the dispensing system operation from the information embodied in the sensor signals (e.g., in the sensor signal pulse trains), comparison between the outputs of thesensors80,84, and externally determined or known information about the tablets and tablet flow direction.
• Thesensor system102 may allow for measurement of speed and time related to tablet dispensing. According to some embodiments, the length of a complete prescribed tablet (hereinafter, “Tablet Length”) is known. With reference toFIG. 13, for each tablet dispensed through thechannel120, thecontroller42 will receive a detection signal pulse JP from theentrance sensor84 and a detection signal pulse CP from theexit sensor80. The pulse JP has a duration or width JPW corresponding to the duration of occlusion of thesensor84 by the tablet. Likewise, the pulse CP has a duration or width CPW corresponding to the duration of occlusion of thesensor80 by the tablet. Thecontroller42 determines the velocity of each tablet through the outlet124 (its “exit velocity”) and the velocity of the tablet through the inlet122 (its “entrance velocity”) using the pulse widths JPW, CPW and the known Tablet Length. More particularly, the exit velocity can be calculated as:
• 
  Tablet Length/Pulse width CPW=exit velocity
• The entrance velocity can be calculated as:
• 
  Tablet Length/Pulse width JPW=entrance velocity
• Additionally, the controller can determine the velocity at which the tablet travels through the channel120 (nozzle velocity) using the known distance (“sensor distance”; e.g., the distance D (FIG. 5)) between the operative trailing edge of the signal from thesensor84 and the operative trailing edge of the signal from thesensor80, and the measured time between pulses (TBP) (i.e., the duration between the end times CP End and JP End of the pulses CP and JP (i.e., the trailing edges of the pulses CP and JP), respectively). Using the trailing edges (CP End and JP End) may assist in determining when an event is over; however, the start times of the pulses CP, JP can be used instead. More particularly, the nozzle velocity can be calculated as:
• 
  sensor distance/(CP End−JP End)=nozzle velocity
• From these measurements and prescribed values, thecontroller42 can “learn” or determine the average exit velocity, the average entrance velocity, and the average nozzle velocity for tablets dispensed through thechannel120. These average values can be applied to specific events (i.e., dispensed tablets) to identify or evaluate additional characteristics of the events.
• According to some embodiments, when the pulses CP, JP for a given tablet indicate that the tablet has passed through thechannel120 at the average nozzle velocity but one or both of the pulses CP, JP has a duration that is less than the average by more than a prescribed amount (e.g., one or two standard deviations), thecontroller42 will identify the tablet as a partial tablet (i.e., a tablet having a length less than the prescribed or standard length for the tablets). Using the pulse duration or width measurements, the known tablet length, and the typical time between signal pulses, thesensor system102 can determine the number of whole tablets and partial tablets that are dispensed, and even the sizes of the partial tablet fragments.
• According to some embodiments, when a detection signal pulse CP, JP from asensor80,84 has a duration that exceeds the average pulse for that sensor by more than a prescribed amount (e.g., one or two standard deviations), thecontroller42 will identify an exception event. Thecontroller42 may further evaluate and catalog the exception event using this and additional available performance information. Thecontroller42 may assess the measured data and compare the measured data to the expected data for known specific events to identify a specific event corresponding to the measured data. Once the event or event type is identified, the controller may perform appropriate corrective action to the count, if any exists. Thecontroller42 may incorporate the states of thevalves142,146 and/or the sequence in which the pulses from thesensors80,84 occurred in determining and cataloging the exception event.
• Thesensor system102 can also provide real time statistics of dispensing performance for thebin100, as well as a record of the performance of thebin100.
• While the sensor system has been described hereinabove with regard to thebin100 and the dispensingsystem40, sensor systems according to embodiments of the present invention may be used with bins and/or systems of other types and configurations. Sensor systems according to embodiments of the present invention may include sensors differently configured than thesensors80,84.
• While embodiments employing forced gas drive mechanisms are described herein, other embodiments of the present invention may employ other drive mechanisms in place of or in addition to forced gas. For example, the pharmaceutical articles may be forced in the forward and/or reverse direction by vibration and/or gravity.
• While various methods are described herein to identify dispensing fault conditions, these methods may also serve to confirm proper count conditions. More particularly, the lack of identification of a dispensing fault condition may be registered or affirm a valid count or count session. Accordingly, sensor systems as disclosed herein may provide improvements in count confidence.
• The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although a few exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention. Therefore, it is to be understood that the foregoing is illustrative of the present invention and is not to be construed as limited to the specific embodiments disclosed, and that modifications to the disclosed embodiments, as well as other embodiments, are intended to be included within the scope of the invention.

Claims (10)

1. A method for dispensing solid pharmaceutical articles using an apparatus including a housing and a sensor system, the housing defining a dispensing channel having a dispensing inlet and a dispensing outlet downstream of the dispensing inlet, the sensor system including first and second sensors spaced apart along the dispensing channel such that the second sensor is located downstream of the first sensor, the method comprising:

forcing at least one article along a path through the dispensing channel;

generating detection signals using the first and second sensors responsive to articles passing through the dispensing channel; and

using the detection signals from the first and second sensors to monitor dispensing performance of the apparatus.

2. The method ofclaim 1 wherein the first sensor is located proximate the dispensing inlet and the second sensor is located proximate the dispensing outlet.

3. The method ofclaim 1 including counting the articles passing through the dispensing channel using at least one of the first and second sensors.

4. The method ofclaim 3 including:

counting the articles passing through the dispensing channel using the second sensor; and

detecting jams of the articles using the first sensor.

5. The method ofclaim 1 wherein forcing at least one article along the path through the dispensing channel includes generating at least one drive gas flow using a flow generator to force the at least one article along the path through the dispensing channel.

6. The method ofclaim 5 including forcing the articles through the dispensing channel using a drive gas jet.

7. The method ofclaim 5 including positively controlling a positive pressure source to provide the at least one drive gas flow.

8. The method ofclaim 1 including dispensing the articles from a hopper chamber of the housing into the dispensing channel.

9-28. (canceled)

29. A method for dispensing solid pharmaceutical articles using an apparatus including a housing and a sensor system, the housing defining a dispensing channel having a dispensing inlet and a dispensing outlet downstream of the dispensing inlet, the sensor system including at least one sensor positioned along the dispensing channel, the method comprising:

forcing at least one article along a path through the dispensing channel;

generating detection signals using the at least one sensor responsive to articles passing through the dispensing channel; and

using a duration of at least one of the detection signals from the at least one sensor to determine whether a dispensing fault condition has occurred.

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