Abstract:
A method is provided for feeding small items, for example pills, that does not require tooling changes or position adjustment regardless of the size or shape of the pills. A first hopper supplies small items to a second hopper that separates the small items. The method incorporates sensors to detect the presence, size and travel time of the pills in the separating bowl hopper. The method uses the sensed values for setting vibration amplitude and the duration of an air flow to discharge pills from the apparatus.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of packaging equipment, and more particularly to equipment to feed small items such as pills for packing in small quantity containers. 
     BACKGROUND OF THE INVENTION 
     Pills are made in a broad variety of sizes and shapes for purpose of identification. The term “pills” is used herein to incorporate tablets, capsules, caplets and gel caps. The size variety of pills also accommodates different drug dosage requirements. While this system is clearly functional for its intended purpose, the variety in size and shape necessitates conventional equipment for packaging pills to be modified in some way to accurately handle, count and package different pills. The modification typically involves either replacing certain parts in a packing machine or adjusting the spacing of parts to be able to linearly feed, separate, count and package the required pills. 
     When a pharmaceutical manufacturer makes pills for commercial distribution, the batch production quantity is normally fairly large and the machine adjustments described are considered to be absorbed by a long production cycle. However, when a secondary packager, also known as a contract packager, or a pharmacy or hospital, needs to package pills, the requirements are often different. One such scenario may be packaging pills in a unit pack for individual doses. In these small quantity packaging situations and where the size or shape pill being packaged changes relatively frequently, changing machine parts or adjusting machine part spacing is relatively onerous and time consuming. Thus a need exists for pill packing equipment, particularly equipment for feeding pills to a packaging machine that can handle many different sizes and shapes of pill without a need for machine part changing or adjusting. 
     SUMMARY OF THE INVENTION 
     The invention disclosed below provides a method for feeding small items, e.g. pills, in a variety of sizes and shapes without the need for changing parts or making adjustments in the feeding apparatus. The feeding method employs two vibratory bowl hoppers in tandem. The upstream bowl hopper is operated intermittently in response to signals from a microprocessor. The microprocessor receives signals from a number of sensors that determine the size and quantity of items in the downstream bowl hopper. The downstream bowl hopper is contoured to feed the items up an incline to a point and then to introduce a downward decline for acceleration and separation of pills. An air flow is triggered by a sensor for discharging individual items from the downstream bowl hopper to a further process station, e.g. a packaging machine. Initial operation includes a learning phase where the microprocessor accumulates sensor data for a determination of the size and traveling speed of the pills being packed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is best understood in conjunction with the accompanying drawing figures in which like elements are identified by similar reference numerals and wherein: 
         FIG. 1  is a diagrammatic array representative of a portion of the variety of sizes and shapes of currently manufactured pills. 
         FIG. 2  is a top plan view of the small part feeding apparatus of the present invention. 
         FIG. 3  is a cross sectional view of the apparatus of  FIG. 2  taken in the direction of line  3 . 
         FIG. 4  is an extended graphical representation of a ramp of the small item feeding apparatus of  FIG. 2 . 
         FIG. 5  is a schematic illustration of the pneumatic circuit of the apparatus of  FIG. 2 . 
         FIG. 6  is a chart of process steps carried out by the method of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1 , a number of pills A, B, C, D, E and F are shown as representative of the variety of pill sizes and shapes that may be fed by the apparatus of the present invention without requiring any part replacement or part position adjustment. As is shown, pills B, D and F are depicted as larger versions of pills A, C and E, being of similar shapes. Other sizes and shapes as are generally known are able to be fed by the invention feeding apparatus. In addition to the variety of sizes and shapes, pills may have different exterior surfaces, thereby resulting in different coefficients of friction and movement speed. Whereas the preferred embodiment of the present invention pertains to feeding pills, it is to be understood that the apparatus and method are adapted to the feeding of different types of small items as well. 
     Referring now to  FIG. 2 , the small item feeding apparatus  10  of the invention is shown in top plan view, comprising a supply bowl hopper  14  and a separating bowl hopper  26 . Supply bowl hopper  14  is mounted at a higher level to overlap a portion of separating bowl hopper  26  (see  FIG. 3 ). An additional supply hopper may be added in the system in a situation where the capacity of supply bowl hopper  14  is insufficient to feed an adequate number of pills for production needs. A number of exemplary pills E are shown in supply bowl hopper  14  from which they are fed to separating bowl hopper  26 . Whereas supply bowl hopper  14  is positioned to discharge pills E into separating bowl hopper  26  at approximately the 3:00 position of hopper  26 , alternate relative orientations between the two hoppers may be used to vary the length of the travel path for pills E. According to the design principles of the invention, pills E of substantially any size or shape will be conveyed to a packaging machine with no need to adjust or exchange components in the apparatus. As described below, the invention apparatus has the ability to spontaneously calibrate operating parameters to accommodate the specific pill or other small item. As illustrated, pills E travel around the peripheral edge of supply bowl hopper  14  in the clockwise direction as indicated by arrow K and around the inner rim of separating bowl hopper  26  in the counterclockwise direction as indicated by arrow M. 
     Referring further to  FIG. 2 , supply bowl hopper  14  is a substantially standard vibratory bowl hopper having a floor portion  16  and a ramp  18 , ramp  18  gradually increasing in height above floor  16  in the clockwise direction to reach a maximum height immediately prior to a discharge chute  22 . Whereas the supply hopper is described as a standard vibratory bowl hopper, it is understood that other types of hopper or supply conveyor capable of feeding pills and being intermittently actuated will function in the invention disclosed. Supply bowl hopper  14  is mounted to position discharge chute  22  overlapping the periphery of separating bowl hopper  26 . Separating bowl hopper  26  is a vibratory bowl hopper that is configured in a unique shape to cause pills E to travel around the inner rim  28  thereof. A first sensor  40 , a second sensor  42  and a third sensor  44  are mounted below hopper  26  radially adjacent to inner rim  28 . As illustrated, first sensor  40  is positioned approximately at the 2:00 position under separating bowl hopper  26 , using standard clock-face numeral positioning terminology, second sensor  42  at the 9:00 position, and third sensor  44  at the 4:00 position. If the relative positioning of supply bowl hopper  14  and separating bowl hopper  26  is changed as described above, the relative position of sensors  40 ,  42  and  44  are also subject to change. The sequential numbering of sensors  40 ,  42  and  44  follow the counterclockwise direction of travel indicated by arrow M, with first sensor  40  designated as the first sensor in the path of pills E entering separating bowl hopper  26  from supply bowl hopper  14 . Sensors  40 ,  42  and  44  in the preferred embodiment, are retro-reflective photoelectric sensors to be used in conjunction with an opposed mirror as described below. Separating bowl hopper  26  is made from a transparent material to allow sensors  40 ,  42  and  44  to view through hopper  26  and sense pills passing thereby. Separating bowl hopper  26  is formed with a substantially conical throat  35  terminating at an exit  36 , a downwardly open hole. A deflector  34  is mounted adjacent to exit  36  and distal from the center of hopper  26 . The path of pills E adjacent to inner rim  28  gradually rises from approximately the 8:00 position counterclockwise to approximately the 11:00 position. From 11:00, the path declines to arrive at the original height at 8:00. Whereas the distance counterclockwise from 8:00 to 11:00 is significantly greater than the distance from 11:00 to 8:00, the decline is steeper than the rise. As each pill E passes a crest at approximately 11:00, pill E accelerates down the decline from 11:00 to 9:00, arriving at second sensor  42 , and a pair of blow off tubes  32  (only one visible in this view) that are positioned approximately at the 9:00 position. The contour continues to decline to the 8:00 position to begin an upward incline. As the leading edge of a pill E descends the decline from 11:00, arriving at second sensor  42 , a microprocessor (not shown) receives an input from second sensor  42 . The microprocessor signals to cause the actuation of a pressurized air supply, resulting in an air flow  38  from tubes  32  to propel pill E into throat  35  and through exit  36  to a packaging machine or the like (not shown). Depending on the mass of pill E, air flow  38  may propel pill E to contact deflector  34  and then downwardly to exit  36 . Depending on the quantity of pills E in separating bowl hopper  26  and the time requirements of the process, numbers of pills E are not discharged to exit  36 . Pills E not discharged continue to travel around separating bowl hopper  26  to be available at discharge throat  35  in a later sequence. 
     Referring now to  FIG. 3 , a cross sectional view is shown as taken in the direction indicated by line  3  of  FIG. 2 . Supply bowl hopper  14  has a substantially flat central floor  16  and a ramp  18  that gradually rises. A vibratory device  24  is affixed to supply bowl hopper  14  to cause vibratory motion thereof. The outer sections of supply bowl hopper  14  are angled downward to encourage pills E to travel around the periphery thereof, as is known. A first exemplary pill E is shown resting toward the outer perimeter of ramp  18 , a second exemplary pill E is shown being transferred from supply bowl hopper  14  to separating bowl hopper  26 , and a third exemplary pill E is shown in front of blow off tubes  32   a  and  32   b.    
     Referring further to  FIG. 3 , separating bowl hopper  26  is formed in a unique configuration. A vibratory device  30  is affixed to separating bowl hopper  26  to cause vibratory motion thereof. Travel path segment  26   a , extending generally from 8:00 to 11:00 in the counterclockwise direction (see  FIG. 2 ) is inclined radially upward toward the periphery of separating bowl hopper  26  at a preferred angle X of approximately 15°. Travel path segment  26   b , extending generally from 11:00 to 8:00 in the counterclockwise direction is inclined radially upward toward the periphery of separating bowl hopper  26  at a preferred angle Y of approximately 5°. A gradual transition is provided of the incline angle from segment  26   a  to segment  26   b  and vice versa. Inclination of segments  26   a  and  26   b  upwardly toward the periphery of separating bowl hopper  26  assures that pills E will travel around hopper  26  in a path adjacent to the inner rim thereof, as shown in  FIG. 2 . Reducing the angle of inclination from approximately 15° to approximately 5° optimizes the discharge of pills E when impinged by an air flow from blow off tubes  32   a  and  32   b . The preferred angles noted are described as being examples, not limitations, on the available angles for inclination of segments  26   a  and  26   b . First photoelectric emitter/sensor  40  is positioned below the base of travel path segment  26   a , and second photoelectric emitter/sensor  42  is positioned below travel path segment  26   b . A mirror  50 , or similar device, is positioned above travel path segment  26   a  in line with first emitter/sensor  40 , and a second mirror  52  is positioned above travel path segment  26   b  in line with second emitter/sensor  42 . Alternative types of sensors than photoelectric sensors are believed to be within the scope of the present invention. Throat  35  is oriented at a downward angle from travel path segment  26   b  to terminate at exit  36 . In use, exit  36  is positioned above an entry of a packaging machine or other device. Deflector  34  is mounted in a manner to permit adjustment of the angle in order to deflect a pill E, being discharged by an air flow from blow off tubes  32   a  and  32   b , into throat  35  and out through exit  36 . As seen in this view, the invention provides a plurality of blow off tubes  32   a  and  32   b , preferably 2 blow off tubes, in a position opposed to exit  36 . Lower blow off tube  32   b  is positioned close to the base of travel segment  26   b  and upper blow off tube  32   a  is positioned an increment H above lower blow off tube  32   b.    
     Referring now to  FIG. 4 , an extended graphical representation is shown of a ramp of separating bowl hopper  26  of  FIG. 2 . As described above in relation to  FIG. 2 , pills E travel in a counterclockwise direction around separating bowl hopper  26 .  FIG. 4  portrays the path length from the 8:00 position to the 11:00 and back to the 8:00 position. Travel path  26   a - 26   b  inclines upward in the counterclockwise direction from 8:00 to a maximum height H at 11:00 to then decline downward to 8:00. The downward slope of the segment from 11:00 to 8:00 is angularly greater than the upward slope of the segment from 8:00 to 11:00 to cause the pills being conveyed to accelerate on the downward slope and become separated from the pills that follow. This separation process enables a discreet sensing of each pill as it approaches the blow off tubes to accurately activate the air flow. A height differential H between the highest point at 11:00 and the lowest point at 8:00 that has been found to be effective for conveying and transporting a variety of pills is approximately 1.1 cm (0.435 inches). Other height differentials are understood to be within the scope of the invention, being dependent on several parameters, including the mass, surface friction and geometry of the pill, the surface friction and vibration characteristics of the bowl hopper, etc. 
     Referring now to  FIG. 5 , a schematic illustration is shown of the pneumatic circuit of the apparatus disclosed herein. For purposes of description, a representation of a smaller pill E and a larger pill F are superimposed on the surface of travel path segment  26   b . Pills E and F are shown after the air flow from blow off tubes  32   a  and  32   b  has been actuated to move pill E or pill F toward exit  36 . Travel path segment  26   b  is oriented at an angle Y that inclines radially upward from the ends of blow off tubes  32   a  and  32   b  at the low point of travel path segment  26   b , angle Y being configured to cause pill E or pill F to reside toward the right (as illustrated). Angle Y is preferably approximately 5° above horizontal. A source S of pressurized air is connected to a hose  58  that is connected on a distal end to an inlet of an accumulator  60 . Accumulator  60  is a reservoir of any arbitrary shape for receiving pressurized air over a time increment. An outlet of accumulator  60  is connected to a hose  62  with the other end of hose  62  connected to an inlet of a valve  66 . An outlet of valve  66  is connected to an inlet of a hose  68  that connects to a second accumulator  70 . Accumulator  70  may be similar to or different from the size of accumulator  60 , while performing basically the same function. Accumulator  70  is connected to blow off tubes  32   a  and  32   b . When the microprocessor opens valve  66 , the pressurized air in accumulator  60  gradually fills second accumulator  70 . As accumulator  70  begins to fill, and pressure begins to increase, a low velocity air flow begins to discharge through blow off tubes  32   a  and  32   b . If smaller pill E is in front of blow off tubes  32   a  and  32   b , the initial low velocity flow mainly from lower blow off tube  32   b  will propel pill E toward exit  36 . If larger pill F is in front of blow off tubes  32   a  and  32   b , the mass of pill F will resist movement until accumulator  70  attains a higher pressure and the air flow through blow off tubes  32   a  and  32   b  is at a higher velocity, the air flow through upper blow off tube  32   a  and lower blow off tube  32   b  both propelling pill F. In addition, the microprocessor maintains valve  66  open for a time interval proportional to the length of the pill being conveyed. Thus, a shorter pill, e.g. pill E, will receive a shorter time value air blast that is sufficient to discharge pill E to exit  36 . Conversely, a longer pill, e.g. pill F, will receive a longer time value air blast needed to discharge pill F to exit  36 . Therefore, a number of features of the present invention are provided to control the discharge velocity of pill E, including positioning an upper blow off tube  32   a  at a height greater than lower blow off tube  32   b  to enable the air flow from upper blow off tube  32   a  to impinge only a larger pill F and impart a greater discharge velocity to pill F. In addition, the duration of the blow off air flow is adjusted automatically according to the size pill being discharged. The use of second accumulator  70  causes the blow off air flow to initially move a smaller pill at a relatively low air velocity and pressure, increasing gradually to move a larger pill with a relatively high air velocity and pressure. 
     In operation, valve  66  is normally closed. Pressurized air from air source S gradually fills accumulator  60  until the pressure within accumulator  60  is equal to the pressure of air source S. According to the preferred embodiment of the invention, the pressure of air source S is set at between 10 psig and 20 psig, most preferably at 15 psig. At this stage, the pressure in second accumulator  70  is substantially equal to atmospheric, or 0 psig. When valve  66  is opened by a signal received from the microprocessor (not shown), the pressurized air from first accumulator  60  flows through hose  62 , valve  66  and hose  68  to enter second accumulator  70 . The air flowing through hose  68  into accumulator  70  causes the pressure inside accumulator  70  to rise over time, eventually reaching a steady state. This rising pressure results in air beginning to flow through blow off tubes  32   a  and  32   b . The rate of pressure rise in accumulator  70  and the related discharge flow gradient through blow off tubes  32   a  and  32   b  is a function of the air pressure, tubing diameter and length and the volume of accumulator  70 . These parameters are specified to result in an air flow through blow off tubes  32   a  and  32   b  which discharges a smaller pill E early in the discharge flow gradient while a larger pill will be discharged later in the discharge flow gradient after steady state has been achieved. Utilization of the discharge flow gradient allows the pressure at source S to be set at a higher level, necessary to discharge the larger/heavier pills without causing the smaller/lighter pills to be discharged with excess velocity. As noted earlier, travel path segment  26   b  is inclined at angle Y of approximately 5° to hold pill E or F toward the center of separating bowl hopper  26  to be close to blow off tubes  32   a  and  32   b , optimizing the effectiveness of air flow  38 , while not being an excessive incline to impede pill movement. 
     Referring further to  FIG. 5 , lower blow off tube  32   b  resides at or incrementally above travel path segment  26   b  to reliably impinge on and discharge a small pill E. Upper blow off tube  32   a  resides at a height H above lower blow off tube  32   b  to impinge a larger pill F. The air flow from lower blow off tube  32   b  will be sufficient to propel smaller pill E to the left (as illustrated), with the air flow from upper blow off tube  32   a  passing over pill E until pill E is higher up the inclined surface of travel path segment  26   b , at which time pill E is in the air flow from both blow off tubes  32   a  and  32   b . As will be understood, when pill E is a greater distance from the exit point of the blow off tubes  32   a  and  32   b , the air flow will be less forceful. The greater mass of larger pill F will resist the initial, low velocity air flow, and only be propelled when the pressure in second accumulator  70  has increased to generate a higher velocity air flow. 
     Referring now to  FIG. 6 , a chart is provided of process steps carried out by the method of the present invention. In step A, a quantity of items, e.g. pills, is loaded into the supply bowl hopper. In step B, power is turned on, causing a supply bowl hopper and a separating bowl hopper to vibrate at a pre-set default amplitude. In step C, the items travel clockwise around the periphery of the supply bowl hopper to a discharge point and transfer to the separating bowl hopper. In step D, the items travel counterclockwise around the inner rim portion of the separating bowl hopper. In step E, a first sensor detects items passing. In step F, a second sensor detects the time for each item to pass. In step G, the second sensor sends a signal to a microprocessor relating to item passing time. In step H, step G is repeated until 10 items have been detected. In step I, the microprocessor averages item passing time readings, discards anomalous readings and re-averages the time readings remaining in the normal range to set a duration for the blow off air blast. In step J, the first and second sensors send signals to the microprocessor for determination of the item travel time between sensors. In step K, the microprocessor calculates the time for each item to travel from the first to the second sensor and adjusts the amplitude of vibration of the separation bowl hopper to set pill travel speed. In step L, when the first sensor continues to see pills and a third sensor detects a first pill, the microprocessor deactivates the vibration of the supply bowl hopper. In step M, after a time period derived from the average pill travel time, the microprocessor re-activates the vibration of the supply bowl hopper. In step N, following the determination of the times for 10 pills to pass the second sensor, when the second sensor detects the leading edge of a pill, the second sensor sends a signal to the microprocessor. In step O, the microprocessor opens a valve, releasing an air flow to discharge the pill through an exit chute. 
     While the description above discloses preferred embodiments of the present invention, it is contemplated that numerous modifications of the invention are possible and are considered to be within the scope of the claims that follow.