CA2203856A1 - Apparatus for dispensing tablets - Google Patents

Abstract

Automatic medication tablet dispensing apparatus, featuring a system capable of authenticating in real-time every tablet that is being counted to reduce the likelihood of errors in the prescription, particularly in the nature of the drug being dispensed. The apparatus includes a scan gate through which every tablet that is being dispensed passes. The gate generates data that is processed to assess the volume of the tablet. The volume value is compared with a reference volume stored in memory. In the absence of match, an error flag is raised an the tablet dispensing operation is terminated. To further reduce the likelihood of errors, the system is designed to enable the tablet dispensing function only when the identity of the drug to be delivered has been entered twice, a first time on a keyboard, and a second time by scanning the bar-code on the medication master container.
Moreover, the apparatus is designed to calculate the total volume of the prescription and to indicate the size of the container that can hold the counted tablet load.

Description

CA 022038~6 1997-04-28 TITLE: APPARATUS FOR L~I~YO~ i TAELETS.

3 Field of the inveneion The present invention relates to a novel tablet dispensing 6 apparatus suitable for medication retailers, such as 7 pharmacies, where customers purchase prescription drugs. The O apparatus is designed to count precisely the number of 9 tablets and dispense them in a c~nt~in~r. In addition, the apparatus has the ability to verify characteristics of the 11 tablets that are being dispensed to ensure that the correct 12 medication is being delivered to the customer.

14 ~a~ ~J O~ the lnvention lS
16 Traditionally, prescription drugs can be purchased by 17 consumers in pharmacies. The consumer is required to produce 18 a prescription document from a doctor that identifies the 19 type of medication and dosage along with other information 20 such as the number of pills to be taken every day, etc. On 21 the basis of this document, the pharmacist retrieves a master 22 container in which the desired type of medication is stored 23 and manually counts the pills until the desired count has 24 been reached. Those pills are then placed in a separate 25 container, preferably provided with a child-proof cap, that 26 is given to the customer. Usually, the container is provided 27 with some sort of label that identifies the kind of 28 medication it contains along with instructions on how and 29 when to take the tablets.
31 This procedure for procurement of prescription drugs has been 32 used for a number of years. Although it is generally 33 satisfactory it presents a number of drawbacks. More CA 022038~6 1997-04-28 particularly, there is always the possibility of error in 2 delivering be wrong drug to the consumer or the correct drug 3 but in the wrong quantity. Presently, the pharmaceutical 4 industry manufactures a wide variety of prescription drugs to treat different illnesses. Most of these drugs are taken in 6 the form of pills which have shapes and colors not very 7 different from one another. Thus, it is difficult to 8 differentiate drugs solely based on visual observation. As 9 such, when the pharmacist selects the master container from which the pills to be dispensed will be taken, there is a 11 real possibility that as a result of lack of concentration or 12 for any other reason the wrong master container is selected.
13 This error may have serious consequences on the patient. In 14 addition to the fact that he will not receive the prescribed drugs, the tablets that he will be taking may harm him.

16 ~ven when the correct drug is being dispensed, the pharmacist 17 may make a mistake when counting the tablets, with the result 18 that the customer may receive more or less than what has been 19 prescribed by the doctor. This situation is potentially less dangerous than the case described earlier, however it 21 constitutes an inconvenience since the customer may be 22 provided with less pills than required in which case he may 23 not be able to complete entirely the medical treatment.

24 Objects and statement of the inrention 26 An object of the invention is to provide an apparatus capable 27 of counting and dispensing tablets that is less likely to 28 deliver to a customer wrong medication or the correct 29 medication but in the wrong quantity.
31 Another object of the invention is to provide a novel system 32 capable of detecting or assessing a certain characteristic of CA 022038~6 1997-04-28 1 a medication tablet.
3 A further object of the invention is to provide a system 4 capable of assessing a certain characteristic of a medication tablet and comparing this characteristic with a reference to 6 generate an error indication in the absence of match.
8 The apparatus, in accordance with the present invention is 9 preferably designed as a small unit that can be conveniently fitted on a counter or table on which a pharmacist will 11 normally dispense the tablets for delivery to customers. The 12 apparatus has a hopper in which the pharmacist will dispense 13 a load of tablets from the master container. An internal 14 counting mechanism will then individually count pills until the desired number is reached. The counted pills are then 16 directed to a channel toward a container that is filled and 17 then given to the consumer. The ~ in;ng pills are diverted 18 in a return line so they can be put back in the master 19 container. Typically, the return line is a separate path of travel in the form of a chute that may lead to the master 21 container. Thus, once the counting function has been 22 completed, the counting mechanism allows the contents of the 23 hopper to pass over the chute and fall in the master 24 container.

The apparatus includes a number of interesting features. One 26 of these features is the ability to indicate to the 27 pharmacist the type of C~nt~lner that will be required to 28 hold the load of tablets to be dispensed. Typically, 29 pharmacists use a number of different size containers, each container being capable of holding different quantities of 31 pills. When the pills are manually dispensed, the pharmacist 32 must make a choice of the type of c~nt~in~r that he assumes 33 will be pensed quantity.

CA 022038~6 1997-04-28 2 The present invention obviates this difficulty by providing 3 a system that can accurately assess the size of the container 4 that will be required and provide an indication to the pharmacist so no arbitrary choice is required. This function 6 can be implemented by an electronic system which chooses the 7 container size based on the number of tablets and also based 8 on the volume of each tablet. These two elements allow the 9 electronic system to establish approximately the volume occupied by the dispensed load. In turn, this information 11 permits the easy selection of the appropriate size container.

12 In a most preferred embodiment, the electronic system 13 includes a keyboard or any other suitable data entry 14 mechanism. The keyboard is connected to a central processor that drives a display. This setup allows the pharmacist to 16 enter data relative to the prescription and, in turn, the 17 processor will display on the display unit desired 18 information. The electronic system also includes a memory in 19 which is stored reference information of the type to be described later. For performing the function of container 21 size selection, the memory may contain a database 22 establishing a corresp~n~rnr~ between every type of 23 medication that the apparatus may dispense, and an associated 24 tablet size or volume. In use, the pharmacist enters on the keyboard a designation that constitutes a unique identifier 26 of the medication to be dispensed. This identifier may be any 27 suitable numeric or alph~ -riC code that uniquely 28 identifies the drug. The next step is to enter on the 29 keyboard the number of tablets that must be dispensed. On the basis of the first data element (drug ID number) the 31 processor retrieves in memory the volume of a tablet 32 associated with this ID number. The volume is then multiplied 33 by the number of tablets, which provides an approximation of CA 022038~6 1997-04-28 1 the volume that the total tablet load will occupy. On the 2 basis of this information, the system then selects a 3 container size that is somewhat bigger than the cavolume. The 4 container size may then be displayed in the form of a code, each code identifying a certain container size. For example 6 code number one designates the smallest c~nt~;n~r~ code two 7 the next step size, etc.

8 In another embodiment, this electronic system may be used to 9 provide error detection by cross-referencing the data manually entered on the keyboard and data read by a bar-code 11 reader, that appears on the master container holding the 12 source of pills. In this embodiment, the system further 13 includes a bar-code reader in the form of a pen or any other 14 type of data acquisition device that may read the bar-code identifying the drug and which appears on the master 16 container. Thus, the pharmacist, before effecting any tablet 17 dispensing first enters on the keyboard a designation of the 18 drug, such us the ID number. The bar code appearing on the 19 selected master container is then read by the system and the data compared. If they match, the counting function is 21 enabled, otherwise the apparatus defaults to a safe state in 22 which no dispensing is authorized. In this condition a 23 suitable message or indication is provided on the display so 24 the pharmacist is made aware of the problem.
26 In a third embodiment of the invention, the tablet counting 27 apparatus includes a system capable of measuring in real time 28 a characteristic of each pill that is being counted and 29 checking this characteristic against a reference to ensure that every pill that is being dispensed is the correct one.
31 This system addresses a potential source of errors that 32 occurs when the pills placed in the master container do not 33 match the labeling and ID codes on it. Another possible CA 022038~6 1997-04-28 1 source of errors is that the master container contains two 2 different types of tablets. These errors are, usually, very 3 difficult to identify solely based on a visual observation, 4 particularly when the different pills have similar shapes and/or colors.
7 In a most preferred embodiment, the system effects a 8 measurement or assessment of the volume of each tablet that 9 is being counted. The resulting mea~uL~ -nt or calculation is then compared with a reference volume corresponding to the 11 tablet that the system is intended to dispense. If a match 12 exists, the tablet is assumed to be of the correct type and 13 the counting function continues. Otherwise, the system is 14 stopped.
16 The volume assessment system comprises an array of light 17 sources and an array of light detectors, each light source 18 being associated with a unique light detector. The light 19 source array and the corresponding light detector array are arranged in segments that form a right angle between them.
21 More specifically, the light source arrays are geometrically 22 arranged to follow a path corresponding to two adjacent sides 23 of a rectangle. The light source detectors, on the other 24 hand, are arranged along the other two sides of the imaginary rectangle. Each light source in the array is momentarily 26 activated to determine if the beam is being crossed by a 27 tablet. A scan cycle is completed when each light source of 28 the array is being fired. In a most preferred embodiment, 29 scan cycles are effected at a frequency of 1 KHz. Thus, within every time frame of 1/1000 of a second, all the light 31 sources are sequentially fired, and the output of the 32 associated light detectors observed.

33 The volume assessment system is arranged such that the CA 022038~6 1997-04-28 1 imaginary plane in which the light beams generated by the 2 sources propagate is normal to the displacement of the pill 3 through the apparatus. Most preferably, the imaginary plane 4 is such that it extends horizontally while the tablet that falls by gravity downward follows a path forming a 90 degree 6 angle with the beams. When the tablet crosses the measurement 7 plane it obstructs a number of light beams. Those beams 8 define a tablet cross-sectional area which is stored in 9 memory. The various cross-sectional areas measured as the pill slides progressively through the measurement plane are 11 combined by taking into account the displacement of the pill 12 through the plane that occurs between successive scan cycles.
13 The resulting measurement is an assessment of the pill 14 volume. What makes this system extremely advantageous is that the measurement can be effected irrespective of the pill 16 orientation while it passes through the measurement plane.
17 This provides a very reliable system capable of precisely 18 measuring the volume of each tablet that is being counted.
19 This allows to provide a sophisticated error detection method by determining if each pill that is being counted corresponds 21 to a reference pill volume associated with the drug that is 22 being dispensed. If no match is found, even for a single 23 pill, the system is interrupted and an error message 24 displayed.
26 Additional refinements enable the system to intelligently 27 determine conditions in which the correct pills are being 28 dispensed, or that the counting mechanism has dropped two 29 pills at the same time rather than a single pill. If two pills fall at the same time, they will pass through the 31 measurement plane as a single block. This block will have a 32 volume approximately double of the reference volume. In this 33 condition, the system may assume that two pills have fallen 34 at the same time and rr,nt;nnr the counting function rather CA 022038~6 1997-04-28 1 than raising an error flag. An error condition is detected 2 when smaller volume changes are observed such as volume 3 meabu,~ -.q less than the reference volume (that may 4 correspond to a pill fragment) or volumes measurements in excess of the reference volume in the range of 15 to 75~, for 6 example.

7 Brie~ ~ .r;p~ of the drawi~lg~

O Figure 1 is a top plan view of the apparatus for dispensing 9 tablets, constructed in accordance with the invention;

Figure 2 is a block diagram of an electronic system for 11 controlling the operation of the apparatus shown in Figure 1;

12 Figure 3 is a top plan view of a volume measuring gate;

13 Figure 4 is a top plan view of the gate shown in Figure 2, 14 illustrating the passage of a tablet through it;

Figure 5 is a top plan view of the gate shown in Figure 4, 16 illustrating the tablet in a different position.

17 D-f ~r;pt;~ of a pre~erred ~ ~ ' ' 18 Figure 1 of the annexed drawings illustrates an apparatus for 19 automatically dispensing tablets, constructed in accordance with the principles of the present invention. The apparatus 21 is designated comprehensively by the reference numeral 10 and 22 includes a main body 12 housing the tablet counting mechanism 23 and the electronic controls, and a hopper 14, mounted on top 24 of the main body 12 in which are placed a load of tablets.

The main body 12 includes a tablet counting mechanism that is g _ CA 022038~6 1997-04-28 1 located immediately below the hopper 14. The tablet counting 2 chAn1rm is constructed to receive at one end a load of 3 tablets and to output the tablets one by one so a precise 4 number of tablets can be delivered.

The apparatus 10 includes an electronic control system 6 schematically depicted in ~igure 2. The electronic control 7 system includes a central processing unit 16 coupled through 8 a bus 18 to a memory 20. The memory has two sections, one 9 containing the code or list of instructions that regulate the operation of the CPU 16, and another section holding data on 11 which the program operates. The CPU 16 is also connected to 12 a keyboard 22 and to a bar-code reader 24, both used to input 13 data to the CPU 16. The CPU 16 can display messages on 14 display device 21.

The program loaded in the memory 20 allows to perform a 16 number of different functions. One of the functions is to 17 indicate to the operator or the apparatus, the size of the 18 container that will be required to hold the entire 19 prescription. To calculate the crntA1nPr size required the operator inputs an identification of the kind of drug to be 21 dispensed, along with the number of pills. This data can be 22 entered either on the keyboard or through the bar-code 23 reader, such as by scanning the bar code on the label of the 24 master container holding the pills that are placed in the hopper 14. The memory 20 contains a table in which are 26 stored individual pill volume measurements for each drug 27 identifier. If the identifier entered on the keyboard or 28 through the bar-code reader is found in the table, the CPU 16 29 retrieves the volume measurement for one pill and multiplies this value by the number of pills to be dispensed. This 31 produces a total prescription volume. On the basis of this 32 volume, the system can then determine what size of crntA1n~r CA 022038~6 1997-04-28 1 is required. Typically, the memory 20 also holds a table of 2 the available container sizes along with a simple 3 identification code or name. When the total prescription 4 volume is determined the system selects from the table the appropriate cnntA;n~r size and shows on the display the 6 associated code, such as code 1, code 2, or small container, 7 medium container, etc. At this point the operator simply 8 takes an empty cnntAinrr of the designated size and places 9 the container under the chute of the apparatus through which the counted tablets are delivered.

11 Another function that the program can realize is to validate 12 the data entered by the operator of the machine to prevent 13 possible errors. More specifically, the systems requires the 14 operator to enter once on the keyboard the identification number of the drug, and then compares the data with the 16 information obtained from the bar-code reader that has been 17 used to scan the label on the master cnntAin~r. If both drug 18 identifiers agree with one another, then the system concludes 19 that the correct medication has been placed in the hopper and thus enables the counting mechanism. Otherwise, the system 21 presents an error message on the display 21.

22 In short, this function allows to eliminate an important 23 source of errors, occurring when the operator of the 24 apparatus places in the hopper 14 the wrong pills. The requirement to enter the drug identification number on the 26 keyboard, and then the scanning of the bar-code on the label 27 of the master container, constitutes two independent data 28 entries operations that must agree with one another, 29 otherwise the tablet dispensing function is not allowed.

CA 022038~6 1997-04-28 1 Another important feature of the apparatus in accordance with 2 the present invention is the ability to authenticate every 3 pill that is being dispensed, thus eliminating errors that 4 may occur when the master cont~;nPr holds different kind of tablets or the label on the container does not match the drug 6 that has actually been placed in the cont~;nPr~ More 7 specifically, the apparatus includes a volume assessment 8 system that allows to measure, with relative precision, the 9 volume of each pill discharged from the tablet counter. The volume data is then compared with a reference volume. If a ll match exists, then the tablet is assumed to be correct, 12 otherwise an error flag is raised and the operation of the 13 machine is interrupted.

14 The volume assessment system has a scan gate through which every pill is discharged by the tablet counting mechanism.
16 The scan gate determines the cross-sectional area of the 17 tablet passing through the gate, at predetermined time 18 intervals. The resulting information can be used to evaluate 19 the volume of the pill. The structure of the scan gate is shown in Figure 3. The scan gate includes an array of light 21 sources, such as light emitting diodes, and a corresponding 22 array of light detectors, such as photo-transistors or 23 equivalent devices. The arrays of light sources and light 24 detectors are geometrically arranged along the sides of an imaginary square, defining a measurement plane. This 26 measurement plane is located at right angles to the path of 27 travel of the tablet through the scan gate. Thus, if the 28 tablet falls by gravity from the counting --~h~n;sm, then the 29 meaYuL~ ~ plane is horizontal.
The array of light sources is divided in two groups of ten 31 individual devices each, each group being distributed along 32 one side of the imaginary square. The array of light sources 33 occupy two adjacent sides of the square. In Figure 3, the CA 022038~6 1997-04-28 1 light sources are identified by circles. The array of light 2 detectors, identified by triangles are disposed such that 3 every detector faces a corresponding light source.

4 In operation, every light source is fired independently and the associated light detector observed to determine if a 6 received signal exists. A received signal will be present if 7 the light beam is uninterrupted, in other words the pill is 8 not blocking the beam. The successive firing of the entire 9 array of light sources constitutes a scan cycle. In the specific embodiment depicted in the drawings, twenty light 11 sources are successively turned on momentarily and the output 12 of the associated light detectors observed. The data for the 13 scan cycle is stored in memory and analyzed. If a tablet is 14 passing through the gate, the results from the scan cycle will show that a number of the light beams have been blocked.
16 By identifying the location of the light source whose beam 17 has been blocked, one can determine the surface area of the 18 tablet at the location of the measurement plane. Figure 4 19 illustrates this element. The black rectangle depicts in cross-section the tablet passing through the scan gate. The 21 surrounding cross-hatched area is the surface that will be 22 observed by the system as being blocked. Note that this 23 surface is larger than the actual cross-sectional area of the 24 tablet since there is a finite number of light sources/detector pairs. To improve the resolution, or 26 granularity of the measurement the number of light 27 sources/detector pairs could be increased.

28 Once the cross-sectional area during the scan cycle has been 29 determined, the value is multiplied by the displacement of the tablet by reference to the gate, that occurs during the 31 time frame separating two scan cycles. This displacement can 32 be calculated on the basis of the tablet acceleration, CA 022038~6 1997-04-28 knowing the point of origin at which the tablet movement was 2 initiated. If the tablet moves solely under the effect of 3 gravity, the distance separating the point of origin at which 4 the tablet was released and the scan gate allows to determine the tablet displacement between successive scan cycles. This 6 distance is usually a fixed value and determined by the 7 relative location of the parts inside the main frame 12.
8 During the next processing step, the cross-sectional area is 9 multiplied by the displacement which produces a volume slice of the tablet for the scan cycle. To obtain the total volume 11 of the tablet, it suffices to add the volume slices 12 calculated for every scan cycle at which the presence of a 13 tablet has been observed in the scan gate.

14 Typically, if at a given scan cycle the presence of an object at the scan gate is noted, the CPU 16 will calculate the 16 associated volume slice and store the value in memory. The 17 volume slices associated with the subsequent scan cycles are 18 then added together which forms a running total of the tablet 19 volume. At every scan cycle this volume increases. The operation is completed when a scan cycle reports no object in 21 the gate. The system then concludes that the tablet has 22 passed completely and issues the accumulated volume value as 23 the total tablet volume.

24 To provide a high measurement resolution, two important factors must be considered. One is the necessity to complete 26 a scan cycle fast enough so no significant pill displacement 27 through the gate occurs between the beginning and the end of 28 the cycle. Second, the scan cycles should be relatively 29 close to one another and occur at known instants in time so as to develop a total volume value based on a significant 31 number of volume slices, rather than few slices. This can be 32 particularly significant for tablets having complex CA 022038~6 1997-04-28 1 geometrical shapes. In a most preferred embodiment, scan 2 cycles are effected at a frequency of 1 KHz. Thus, within 3 every time frame of 1/1000 of a second, all the light sources 4 are sequentially fired, and the output of the associated light detectors observed.

6 One of the important advantages of this system is the ability 7 to measure the volume of the pill irrespective of the pill 8 orientation as it passes through the scan gate. This allows 9 to greatly simplify the internal construction of the apparatus, as what is now required is a mechanical device 11 that counts and simply drops the pills that pass through the 12 scan gate. There is no nese the pill in any particular 13 orientation or provide guides or other devices that will 14 somehow control the position of the pill relative the scan gate.

16 Once the pill volume has been assessed, it is compared with 17 a reference volume in memory. If a difference in the order 18 of 15~ to 75~ exists, the system then concludes that an 19 incorrect pill, or a fragment of a pill has passed and interrupts the counting operation. An error flag is raised 21 and the appropriate message displayed on the display device 22 21. An exception to this case is when the measured volume is 23 precisely the double of the reference volume. The system may 24 then be programmed to raise the error flag, or to conclude that two pills have passed simultaneously through the scan 26 gate. Instead of interrupting the operation of the 27 apparatus, the total pill count is incremented by two and the 28 operation continues.

29 Strategies can be developed to determine with more certainty whether the double volume measurement event results from two 31 pills passing through the scan gate or the wrong pill. One CA 022038~6 1997-04-28 1 possibility is to count the number of scan cycles during the 2 passage of the pill through the scan gate. If two pills have 3 passed, in all l;krl;h~od they will not be perfectly side by 4 side. Rather, the pills will be longitudinally offset with the result that the scan gate will report the passage of a 6 long object. Such observation can then be interpreted as two 7 pills rather that a single wrong pill.

8 Another possible strategy is to perform shape analysis to 9 further refine the intelligence of the system in detecting wrong pills. One possibility is to measure during the 11 passage of the pill through the scan gate maximal dimensions, 12 such as width, height or length, based on the number of beams 13 interrupted. Those dimensions will not be seen every time a 14 pill passes through the scan gate, as the maximal observed dimension is dependant upon the pill orientation. However, 16 if the maximal dimension seen exceeds the absolute maximal 17 dimension of the tablet, the be detecting the wrong tablet 18 that may or may not have a volume that is about the same as 19 the reference volume. A somewhat simpler approach is to rely on the cross-sectional area of the tablet observed at every 21 scan cycle. For every tablet, there will be a maximal cross-22 sectional area values. Thus, irrespective of the tablet 23 orientation, the cross-sectional area observed at the gate 24 will invariably be equal or less than the maximal value.
This maximal value is established solely by the geometrical 26 shape of the tablet. Thus, if the scan gate reports a cross-27 sectional value above the maximum, in all likelihood the 28 wrong pill or a foreign object other than a pill is passing.
29 Those embodiments require the presence in the memory 20 of the appropriate reference values associated with the drug ID
31 code or identifier.

CA 022038~6 1997-04-28 1 The above description of the invention should not be 2 interpreted in any limiting manner as refinements and 3 variations are possible without departing from the spirit of 4 the invention.

Claims (8)

1. An apparatus for detecting presence of items travelling in sequential order, said apparatus including:
a) a detection station including a scan gate through which items can pass in sequential order;
b) said detection station capable of generating in response to passage of an item through said scan gate data indicative of an approximate volume of the item;
c) processing means for receiving and processing said data to register presence of an item in said detection station.

2. An apparatus as defined in claim 1, wherein said scan gate is capable of measuring a cross-sectional area of an item as the item passes through said scan gate at different instants in time.

3. An apparatus as defined in claim 2, wherein said scan gate includes an array of sources of radiating energy and an array of detectors of radiating energy, the detectors of said arrays being disposed such that a given source of radiating energy is associated with a given detector of radiating energy thereby the given detector is capable of detecting radiating energy generated by the given source, the sources of radiating energy and the detectors of the radiating energy being disposed in a measurement plane, whereby passage of an item through said measurement plane blocking passage of radiant energy toward a certain number of detectors, the certain number of detectors permitting to assess a cross-sectional area of the item at a certain instant in time.

4. An apparatus as defined in claim 3, wherein said array of sources and said array of detectors are arranged in said measuring plane such as to provide measurement of transverse dimension of the item along two generally orthogonal directions.

5. An apparatus as defined in claim 4, wherein the radiating energy is light.

6. A method for detecting presence of items travelling in sequential order, said method comprising the steps of:

a) passing an item through a detection station to generate data indicative of an approximate volume of the item;
b) processing said data to confirm presence of the item in the detection station.

7. An apparatus for counting small items transported in sequential order, said apparatus including:
a) a detection station including a scan gate through which items can pass in sequential order;
b) said detection station capable of generating in response to passage of an item through said scan gate data indicative of an approximate volume of the item;
c) processing means receiving the data generated at each passage of an item through said detection station and processing the data to keep a count of the items that have passed through said detection station.

8. An apparatus for identifying items travelling in sequential order, said apparatus including:
a) a detection station including a scan gate through which items can pass in sequential order;
b) said detection station capable of generating in response to passage of an item through said scan gate data indicative of an approximate volume of the item;