Methods and apparatus for dispensing solid pharmaceutical articles

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.

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.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

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 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. 2-8and designated broadly therein at40(FIGS. 2 and 3). The dispensing system40includes a sensor system102(FIG. 8) according to embodiments of the present invention. The system40includes a support frame44for the mounting of its various components. Those skilled in this art will recognize that the frame44illustrated herein is exemplary and can take many configurations that would be suitable for use with the present invention. The frame44provides 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.

The system40generally includes as operative stations a controller (represented herein by a graphical user interface42), a container dispensing station58, a labeling station60, a tablet dispensing station62, a closure dispensing station64, and an offloading station66. In the illustrated embodiment, containers, tablets and closures are moved between these stations with a dispensing carrier70; however, in some embodiments, multiple carriers are employed. The dispensing carrier70has the capability of moving the container to designated locations within the cavity45of the frame44. Except as discussed herein with regard to the dispensing station62, 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.

The controller42controls the operation of the remainder of the system40. In some embodiments, the controller42will be operatively connected with an external device, such as a personal or mainframe computer, that provides input information regarding prescriptions. In other embodiments, the controller42may 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, the controller42signals the container dispensing station58that a container of a specified size is desired. In response, the container dispensing station58delivers a container for retrieval by the carrier70. From the container dispensing station58, the container is moved to the labeling station60by the carrier70. The labeling station60includes a printer that is controlled by the controller42. The printer prints and presents an adhesive label that is affixed to the container.

Filling of labeled containers with tablets is carried out by the tablet dispensing station62. The tablet dispensing station62comprises 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 the bins100will hold different tablets). Referring toFIGS. 4 and 5, the dispensing bins100, which may be substantially identical in size and configuration, are organized in an array mounted on the rails of the frame44. Each dispensing bin100has a dispensing passage or channel120with an outlet124that faces generally in the same direction, to create an access region for the dispensing carrier70. The identity of the tablets in each bin is known by the controller42, which can direct the dispensing carrier70to transport the container to the proper bin100to fill the particular prescription. In some embodiments, the bins100may be labeled with a bar code or other indicia to allow the dispensing carrier70to confirm that it has arrived at the proper bin100.

The dispensing bins100are configured to singulate, count, and dispense the tablets contained therein, with the operation of the bins100and the counting of the tablets being controlled by the controller42. Some embodiments may employ the controller42as the device which monitors the locations and contents of the bins100; others may employ the controller42to monitor the locations of the bins, with the bins100including indicia (such as a bar code or electronic transmitter) to identify the contents to the controller42. In still other embodiments, the bins100may generate and provide location and content information to the controller42, with the result that the bins100may be moved to different positions on the frame42without the need for manual modification of the controller42(i.e., the bins100will update the controller42automatically).

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 the tablet dispensing station62, the dispensing carrier70moves the filled container to the closure dispensing station64. The closure dispensing station64may house a bulk supply of closures and dispense and secure them onto a filled container. The dispensing carrier70then moves to the closed container, grasps it, and moves it to the offloading station66.

Turning to the bins100in more detail, an exemplary bin100is shown in more detail inFIGS. 4-8. The bin100includes a housing110having a hopper portion112and a nozzle114.

Referring toFIG. 6, the hopper portion112defines a hopper chamber112A that can be filled with tablets T. A lower screen130A is provided in the floor of the hopper portion112and an upper screen130B is provided in the ceiling of the hopper portion112. As discussed below, air or other suitable gas can be flowed through the screens130A,130B and the chamber112A to agitate the tablets T contained therein.

With reference toFIG. 5, the nozzle114defines a dispensing channel120through which the tablets T can be dispensed one at a time. The dispensing channel120has an inlet122adjacent and fluidly connecting the channel120to the chamber112A. The dispensing channel120has an outlet124downstream from and opposite the inlet122and through which tablets may exit the nozzle114to be dispensed into the container C (FIG. 7).

The housing110further includes a low pressure port132and a high pressure nozzle134(FIGS. 4 and 6). A door132A is provided to selectively open and close the port132by operation of an associated solenoid132B.

With continued reference toFIG. 5, a forward jet passage140is fluidly connected to the high pressure nozzle134and terminates in a forward jet aperture140A at the dispensing channel120. A forward control valve142is operable to control airflow to the jet aperture140A. A rearward or reverse jet passage144is also fluidly connected to the high pressure nozzle134and terminates in a rearward or reverse jet aperture144A at the dispensing channel120. A reverse control valve146is operable to control airflow to the jet aperture144A.

According to some embodiments and as described in U.S. Patent Publication No. US-2006-0241807-A1, the tablet dispensing station62includes a low pressure manifold74fluidly 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) the screen130A, the chamber112A, the screen130B and the port132to agitate tablets within the hopper chamber112A (FIG. 6). Also, a high pressure (i.e., about 30 psi) conduit72fluidly connected to a high pressure source (not shown) is fluidly connected to the high pressure nozzle134to supply high pressure air to the jet apertures140A,144A. Further, a connector circuit board77is mounted horizontally below the manifold74. The circuit board77or other electrical connector provides an electrical connection between the controller42and a bin-controlling circuit board78(or other electronic component) of the bin100for power and data signals to/from the controller42.

The sensor system102includes a front or exit sensor80and a rear or entrance sensor84positioned along the channel120. The exit sensor80is located downstream (i.e., in the forward or dispensing direction of the tablet flow path through the dispensing channel120) from the entrance sensor84along the dispensing channel120. The exit sensor80is mounted in the nozzle114proximate the outlet124and distal from the inlet122and faces the channel120. The entrance sensor84is mounted in the nozzle114proximate the inlet122and distal from the outlet124and also faces the channel120. The sensors80,84are tablet detecting sensors and are operably connected to associated sensor receiver/processor electronics. The sensors80,84may be electrically connected to an associated controller by lead wires80A,84A. According to some embodiments, the associated controller is or includes the controller42and/or the circuit board78. As further discussed below, the sensors80,84are configured and positioned to detect the tablets T as they pass through the dispensing channel120. The sensors80,84and the associated controller42together comprise a sensor system102operative to monitor flow of tablets T through the channel120and, thereby, dispensing performance of the bin100. According to some embodiments, the controller42uses detection signals from at least one of the sensors80,84to count the dispensed tablets. According to some embodiments, at least the exit sensor80is used for this purpose. In some cases, the sensor system operates the valves142,146or other devices in response to identified or determined conditions or performance in dispensing. While two sensors80,84are 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, the sensors80,84are photoelectric sensors. According to some embodiments, the sensors80,84are infrared (IR) sensors. According to some embodiments, photoemitters82and86(e.g., IR emitters) are mounted in the nozzle opposite the sensors80and84, respectively, to emit photoemissions toward the respective sensors80,84across the channel120. The photoemitters82,86may be operatively connected to the controller42or circuit board78by wires82A,86A. According to some embodiments, all or some of the components80,84and82,86may include both a photoemitter and a photodetector, whereby the components82,86may also serve as sensors. For the purpose of explanation, the illustrated embodiment will be described with only the components80,84being sensors (i.e., the sensors80,84receive photoemissions from the photoemitters82,86). Other types of sensors may be employed as well. Other suitable types of sensors may include, for example, UV, RF, capacitive and EMF sensors.

The exit sensor80and the entrance sensor84are spaced apart along the channel120a 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 the respective 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, the entrance sensor84is positioned along the channel120at, in or immediately adjacent the inlet122. According to some embodiments, the exit sensor80is positioned along the channel120at, in or immediately adjacent the outlet124.

Exemplary operation of the dispensing system40will now be described. The bin100is filled with tablets T to be dispensed. The tablets T may initially be at rest as shown inFIG. 5. At this time, the valves142,146are closed so that no gas flow is provided through the jet outlets140A,144A.

To fill the container C, the dispensing carrier70, directed by the controller42, moves the container C to the exit port of the selected dispensing bin100. The controller42signals the solenoid132B to open the door132A. This opening of the door132A draws low pressure air up through the hopper chamber112A to the manifold74, thereby agitating the tablets T contained in the hopper chamber112B.

Once agitation has commenced, the controller42signals the forward valve142to open (while the reverse valve146remains closed). The opened valve142permits the pressurized gas from the gas source72to flow through the passage140and out through the forward drive jet outlet140A. The pressurized flow from the jet 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 dispensing channel120in a dispensing direction (FIG. 6). Tablets T are oriented into a preferred orientation by the shape of the inlet122to the dispensing channel120and dispensed into the container C through the dispensing channel120and the outlet124under the force of the forward flow FF.

Once dispensing is complete (i.e., a predetermined number of tablets have been counted by the controller42as dispensed), the controller42activates the forward valve142to close and the reverse valve146to open. The opened valve146permits the pressurized gas from the gas source72to flow through the passage144and out through the reverse drive jet outlet144A. The pressurized flow from the jet 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 dispensing channel120toward the chamber112A in a reverse or return direction. In this manner, the airflow is reversed and any tablets T remaining in the channel120are returned to the chamber112A under the force of the reverse flow (FIG. 7).

While, in the foregoing description, the controller42controls the valves142,146, the valves142,146may alternatively be controlled by a local controller unique to each bin100. The bin100can be filled or replenished with tablets via access from a pivoting door127(FIG. 5) located at the upper rear portion of the bin100, for example. As disclosed in U.S. Patent Publication No. US-2006-0241807-A1, the bin100may include components that permit the entry to the dispensing channel120to 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 the bin100such that tablets T will not feed into or through the dispensing channel120under the force of the forward flow FF. A jam is indicated if the entrance sensor84has not detected a pill within a specified time period (e.g., one second). When a tablet jam is identified by the controller42, the controller42will close the forward valve142and open the reverse valve146to generate the reverse flow FR to clear a perceived tablet jam. This action of the controller42may be referred to as issuing a “jam clear”.

According to some embodiments, the controller42will 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 the sensors80,84. According to some embodiments, the calibration procedure includes opening the reverse valve146to generate the reverse flow FR while calibrating the sensors80,84. This may ensure that no tablets or tablet fragments occlude the sensors80,84and thereby corrupt the calibration. The controller42may conduct the calibration procedure automatically and/or shortly or immediately after a dispensing session and the bin100may 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”). The sensors80,84detect the tablets T as they pass through predetermined points in the dispensing channel120, as discussed in more detail below. The controller42uses the detection signals from the sensors80,84to monitor and maintain a registered count of the tablets T dispensed (“the system count”). When the system count matches the requested count, the controller42will 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 the sensor system102of the bin100and methods in accordance with embodiments of the present invention. According to some embodiments, the entrance sensor84proximate the inlet122of the channel120performs the duty of detecting tablet jams and the exit sensor80proximate the exit or outlet124performs 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 dispensing channel120during a jam clear. The two sensors80,84can 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 the bin100. Some exception events and corresponding operations of the bin100that 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 the channel120in or closely adjacent the inlet122prior to actuation of the forward valve142to 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 dispensing channel120are not fully returned to the hopper chamber112A by a reverse flow or “jam clear” intended to clear the dispensing channel120, for example. A preload dispensing fault condition may also occur when tablets unintentionally migrate into the dispensing channel120from 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 the hopper chamber112A and into the inlet122or the dispensing channel120. In prior art single sensor systems, upon initiation of the forward flow FF, the two or more preloaded tablets may travel down the channel120in 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 the entrance sensor84. More particularly, the entrance sensor84is configured and located with respect to the dispensing channel120and the inlet122such that, in the case of a preload dispensing fault condition, one or more of the tablets will occlude the entrance sensor84. When this condition occurs prior to initiation of the forward flow FF, the entrance sensor84will provide a detection signal to the controller42indicating that the one or more tablets is/are at the entrance sensor84. In response to the detection signal from the entrance sensor84prior to initiating the forward flow FF, the controller42identifies the existence of the preload dispensing fault condition. Further in response, the controller42will thereafter open the reverse valve146to generate the reverse flow FR to force any tablets T lingering in the channel120back into the hopper chamber112A. In this manner, the channel120is 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 dispensing channel120between the entrance sensor84and the exit sensor80prior to actuation of the forward valve142to generate the forward flow FF. The preloaded tablets may not occlude the entrance sensor84. According to some embodiments of the present invention, preload dispensing fault conditions of this type are identified and corrected by continuously monitoring the entrance sensor84even when the bin100is idle. According to some embodiments, the entrance sensor84is 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, the entrance sensor84is also continuously monitored throughout the calibration period. According to some embodiments, the entrance sensor84is continuously monitored at all times. If a tablet is detected by the entrance sensor84during the idle period, the controller42identifies the existence of a preload dispensing fault condition. The controller42may respond to the identified fault condition by generating the reverse flow FR to force any tablets lingering in the channel120back into the hopper chamber112A. In this manner, the channel120is cleared and the preload dispensing fault condition is removed prior to the onset of tablet dispensing.

The sensor system102may employ the following method to address a “tandem dispensing fault condition.” With reference toFIG. 9, when a tandem dispensing fault condition is present, the controller42may 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 the entrance sensor84is not relied upon to sense preloaded tablets or the tandem condition is not detectable because the configuration/locations of the tablets do not cause the sensor84to immediately start with a tablet detection. The outputs of the sensors80,84are monitored by the controller42and compared. Each of the two tablets passes the entrance sensor84in immediate succession, which causes the entrance sensor to generate a single pulse P2as represented by the signal pulse graph A) ofFIG. 9. The signal pulse P2has a duration that is larger than that of a prescribed or average reference duration for a single tablet passing the sensor84during dispensing. Thereafter, the two tablets pass the exit sensor80in immediate succession, which causes the exit sensor80to generate one continuous, long duration signal pulse P4as represented by the detector pulse graph B) ofFIG. 9. The signal pulse P4has a duration that is larger than that of a prescribed or average reference duration for a single tablet passing the sensor80during dispensing. The controller42compares the durations of the signals P2, P4with the corresponding expected or average signal pulse durations and also compares the time TBP between the pulses P2, P4with the expected or average time between pulses for standard operation, and determines that a tandem dispensing fault condition has occurred. In response, the controller42may increment the system dispensed count by an appropriate amount and/or alert an operator. The expected or average signal pulse durations for the sensors80,84and the expected or average time between the pulses of the sensors80,84may be determined using average entrance, exit and nozzle velocities determined as described below.

In some cases, a first tablet T lingers in the dispensing channel120during 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 the channel120in 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 the exit sensor80and the entrance sensor84. More particularly, the outputs of the exit sensor80and the entrance sensor84are monitored by the controller42and compared. In the case of a collision dispensing fault condition, each of the two tablets passes the entrance sensor84in turn and with spacing between the tablets, which causes the entrance sensor84to generate two discrete signal pulses P10, P12in sequence over time, as represented by the signal pulse graph A) ofFIG. 10. These two pulses P10, P12have a duration corresponding to a typical single tablet. Thereafter, the two tablets pass the exit sensor80in immediate succession, which causes the exit sensor80to generate one long duration signal pulse P14as represented by the detector pulse graph B) ofFIG. 10. The controller42compares the signals P10, P12, P14from the sensors80,84and determines that a collision dispensing fault condition has occurred. In response, the controller42may increment the system dispensed count total by the appropriate amount (in this example, two). Alternatively, in response, the controller42may 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 the exit sensor80and the entrance sensor84, and the direction of drive gas flow. More particularly, the outputs of the exit sensor80and the entrance sensor84are monitored by the controller42and compared. Each signal pulse from the exit sensor80will be accounted for if preceded by a corresponding signal pulse from the entrance sensor84. Under normal (nonfault) conditions, each tablet drawn from the hopper112A passes the entrance sensor84and then the exit sensor80and generates corresponding signal pulses in sequence. In the case of an aspiration dispensing fault condition, a tablet previously counted as dispensed passes the exit sensor80, which causes the exit sensor80to generate a signal pulse P20as represented by the detector pulse graph B) ofFIG. 11. Thereafter, the tablet passes the entrance sensor84, which causes the entrance sensor84to generate a signal pulse P22as represented by the detector pulse graph A) ofFIG. 11. The controller42determines that the drive gas flow was in the reverse direction when the pulses P20, P22were generated and compares the signals P20, P22from the sensors80,84. The controller determines that the exit signal pulse P20did not have a corresponding preceding entrance sensor pulse and the exit sensor detection pulse P20was triggered or generated prior to the entrance sensor detection pulse P22. From this, the controller42determines that an aspiration dispensing fault condition has occurred. In response, the controller42may decrement the system dispensing count total by one. Alternatively, in response, the controller42may 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 the entrance sensor84instead of the counting sensor80. More particularly, the controller42monitors the entrance sensor84. If a tablet is not detected by the entrance sensor84within a prescribed length of time (wait time) while the forward drive gas flow (i.e., the dispensing flow) is being generated, the controller42will identify a tablet jam condition. Responsive to the tablet jam condition, the controller42will issue a jam clear (i.e., open the reverse valve146to generate a burst or sustained reverse flow FR). In this manner, the entrance sensor84“guards” the exit sensor80.

The sensor system102may additionally or alternatively employ the following method to identify and correct a tablet reversal dispensing fault condition by monitoring the exit sensor80, the entrance sensor84, and the direction of drive gas flow. The outputs of the exit sensor80and the entrance sensor84are monitored by the controller42and compared. In the case of a tablet reversal dispensing fault condition, a tablet passes the entrance sensor84(which causes the entrance sensor84to generate a typical duration signal pulse P30as represented by the detector pulse graph A) ofFIG. 12), thereafter passes the exit sensor80(which causes the exit sensor80to generate an extra long duration signal pulse (or two signal pulses as shown by the dotted line) P32as represented by the detector pulse graph B) ofFIG. 12), and thereafter again passes the entrance sensor84(which causes the entrance sensor84to generate a typical duration signal pulse P34). The controller42determines that the drive gas flow was in the forward direction during the pulse P30and in the reverse direction during the pulse P34, compares the signals P30, P32, P34from the sensors80,84, and determines that a tablet reversal dispensing fault condition has occurred. In response, the controller42may decrement the dispensing count total by one. Alternatively, in response, the controller42may 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, the sensor system102may 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 the sensors80,84, and externally determined or known information about the tablets and tablet flow direction.

The sensor system102may 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 the channel120, the controller42will receive a detection signal pulse JP from the entrance sensor84and a detection signal pulse CP from the exit sensor80. The pulse JP has a duration or width JPW corresponding to the duration of occlusion of the sensor84by the tablet. Likewise, the pulse CP has a duration or width CPW corresponding to the duration of occlusion of the sensor80by the tablet. The controller42determines 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 the sensor84and the operative trailing edge of the signal from the sensor80, 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, the controller42can “learn” or determine the average exit velocity, the average entrance velocity, and the average nozzle velocity for tablets dispensed through the channel120. 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 the channel120at 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), the controller42will 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, the sensor system102can 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 a sensor80,84has a duration that exceeds the average pulse for that sensor by more than a prescribed amount (e.g., one or two standard deviations), the controller42will identify an exception event. The controller42may further evaluate and catalog the exception event using this and additional available performance information. The controller42may 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. The controller42may incorporate the states of the valves142,146and/or the sequence in which the pulses from the sensors80,84occurred in determining and cataloging the exception event.

The sensor system102can also provide real time statistics of dispensing performance for the bin100, as well as a record of the performance of the bin100.

While the sensor system has been described hereinabove with regard to the bin100and the dispensing system40, 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 the sensors80,84.

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.