Medication tablets are manufactured in a large number of different sizes and shapes. If a cassette is fitted with an ejection mechanism designed to release one particular shape of tablet, it often will not operate reliably to eject a different shape of tablet. Also, jamming of the mechanism can occur if it receives two tablets at the same time.

Object of the invention An object of this invention is to provide a cassette which is able to discharge reliably more than one shape or size of tablet.

The invention In accordance with the present invention a cassette for fitting to tablet-dispensing apparatus intended to hold several such cassettes each for discharging a different shape of tablet, is provided internally with a tablet-holding chamber, a guide-way along which a stream of tablets travels towards a discharge position in the cassette during operation of the apparatus, a single-tablet selector which operates to prevent more than one tablet at a time from advancing into the discharge position, a displaceable mechanism at the discharge position and having a pocket for the reception of a single tablet and displaceable to convey the tablet to an ejection orifice, means on the cassette for

enabling the displacement of the mechanism to be controlled by the apparatus, and a latch which prevents the mechanism operating until the cassette is fitted to the apparatus.

Preisrrs features of the invention Preferably a closure is provided which may take a form of a shutter and which only opens the ejection orifice when the mechanism is at a position at which ejection of a tablet held in its pocket can take place.

Suitably the mechanism is replaceably fitted on the outside of the cassette. Conveniently the selector is also replaceably fitted but is mounted on the inside of the cassette. The selector and the mechanism provide a set suited for use with a particular shape or size of tablet with which the cassette is to be loaded. If the size or shape of the tablet is to be changed, a different set of mechanism and selector may be fitted to the cassette in place of the original set. It is found in practice that despite the large number of tablet shapes and sizes available on the market to be dispensed in response to a medical prescription, virtually all of them can be accommodated by twenty-four sets of mechanism and selector. In practice, the commonest tablets which are prescribed can be accommodated by four such sets.

In the preferred arrangement, the cassette is moulded from plastics material and the latch is integrally moulded with the cassette and provides a resiliently-biased stop on the body of the cassette and which is biased towards a position at which it blocks displacement of the mechanism. The stop is moved against the bias out of the path of the mechanism by the action of fitting the cassette into its compartment in the apparatus.

Introduction to the drawings The invention will now be described in more detail, by way of example, with reference to the accompanying largely diagrammatic drawings, in which:- in tha drawings FIGURE 1 corresponds to figure 4 of the aforesaid International Patent Application and is provided with reference numerals which denote parts described in the particular description of the aforesaid International Patent Application hereby inserted by way of reference;

FIGURE 2 is plan view of the underside of a cassette after removal of its underlid and shows in sketches A and B a mechanism which is attached to the underside of the cassette, in each of its two operating positions, respectively ; FIGURE 3 is a plan view of the cassette after removal of its top lid ; FIGURE 4 is a plan view of the underside of an underlid provided for the cassette ; FIGURE 5 is a plan view of the top lid ; and, FIGURE6 shows in plan a moulding produced by an injection process and which provides four sets each comprising a mechanism and an associated selector plate.

Description of preferred embodiment For a detailed description of the apparatus shown in figure 1 reference should be made to our co-pending International Patent Application referred to above. Each of the cassettes to which the present invention is applied, are referenced 28 in figure 1.

The cassette shown in figures 2 and 3 is referenced 2. It is moulded from a plastics material and has a cylindrical pivot shaft 3 integrally moulded in its underside as shown in figure 2. The cylindrical body of thesbaft is embraced by a circular groove (not shown) and its circumference is slotted to provide four arcuate portions 5 which flex inwardly temporarily when a mechanism 6 is removably fitted to the underside of the cassette.

This allows the mechanism to pivot about the groove axis while being held on the cylindrical body by the four portions 5.

The mechanism 6 comprises an arm 7 having a hole at one end formed with an inwardly turned lip which can be snap-fitted over the cylindrical body of the shaft 3 so that the inward lip is received by the circular groove of the shaft 3 to allow the mechanism 6 to displace arcuately between two positions shown respectively in sketches A and B. A closure shutter 8 forms part of the mechanism 6 and participates in the arcuate displacements of the mechanism when it is reciprocated by a push rod 400, shown in figure 1, and which forms part of the apparatus. The push rod engages with a pin 10

which projects downwardly from the underside of the mechanism 6 adjacent the stub shaft 3, as shown in figure 2.

A latch 11 is provided by a rectangular section integral with the moulding and which, at its free end 15, engages an abutment surface 12 formed on the mechanism 6. The latch 11 can flex upwardly from the position illustrated in sketch"A"of figure 2 at which its upper surface forms a continuation of the floor of a chamber 13 formed within the cassette. Such upward flexing occurs when a central fin 14 (see figure 2) on the latch is pressed upwardly by a portion of the apparatus on the floor of the compartment into which the cassette is fitted. When such upward movement of the latch 11 occurs, its free end 15 ceases to abut against the abutment surface 12 of the mechanism 6 which can then displace arcuately from the position illustrated in figure 2, sketch A, to the position illustrated in figure 2, sketch B.

Figure 3 shows the interior of the cassette 1. It is formed with a tablet-holding chamber 16 providing a central well 13 partially surrounded by an upwardly spiralling inclined track 17 extending around the inside surface of a peripheral wall 18 of the cassette. The track 17 provides a guide path along which individual tablets can ascend from the well 13 of the cassette to a discharge position 20 when the cassette is arcuately appropriately vibrated in the horizontal plane.

A replaceable selector plate 21 is located at the discharge position 20 and is manually inserted into the position illustrated, by sliding its leading and trailing edges portions respectively referenced 22 and 23 between holding tabs 24 integrally moulded with the cassette. The selector 21 illustrated in figure 3 differs in shape from the four differently- shaped selector plates 50-53 shown in figure 6 but all of them can be interchangeably fitted with selector 21, in the same position to the one shown in figure 3. The selector 21 illustrated in figure 3 has a guide plate 25 of sector shape and which allows one tablet at a time to enter a pocket 26 provided in the upper surface of the mechanism 6 when the pocket is positioned directly beneath a rectangular window 27 provided in the selector 21. If a file of tablets is ascending the spiral track 17 and there is already one tablet in the pocket 26, succeeding tablets are deflected inwardly of the chamber 16 by the curved edge of the guide plate 25 so that they are returned to the well 13. The pocket 26 has its radially outer side, which lies against the curved inside surface of the wall 18, open.

The mechanism 6 operates to convey a tablet loaded into the pocket 26, along the underside of the guide track 1 7 from the position shown in sketch A of figure 2, to a position at which the open outer side of the pocket 26, registers with an ejection orifice 30 as shown in sketch B of figure 2. The orifice 30 ! eads into a discharge chute 31.

This discharge chute 31 is formed by a stack of aligned chute sections arranged one above the other and each integrally formed with a respective cassette. These chute sections, together, form the chute 31 down which tablets ejected from the individual cassettes fall. The movement of the pocket 26 to the tablet ejection position, simultaneously produces movement of the closure shutter 8 away from the orifice 30.

When the apparatus is operating, a tablet within the pocket 26 displaces outwardly and passes through the now-open ejection orifice 30 and down the chute 31. The ejection of the tablet is assisted partly by the sudden change in direction of the arcuately-moving mechanism 6 at the end of its stroke, and partly by the shape of one end wall of the pocket 26 which acts to assist the deflection of a tablet cleanly through the orifice 30 and into the chute 31.

The various sets of interchangeable selector plates 50-53 and corresponding ejector mechanisms 60-63 shown in figure 6 correspond individually to a number of sizes and shapes of tablets with which they are to be used. Hence their respective pockets 70-73 have different shapes. Each of the mechanisms 6 can be individually snap-fitted into position on the stub shaft 3 on the underside of the cassette in an interchangeable manner. The selector plates 50-53, each of which is associated with a respective mechanism 6, are also individually slid into position by engaging their leading and trailing edges 22,23 (see figure 3) between the two sets of tabs 24 as shown in figure 3.

After ejection of a tablet down the chute 31, the mechanism 6 returns to the position shown in sketch"A", of figure 2. If the cassette is to be removed from the apparatus, it is extracted from its compartment and the latch 11 returns to the position shown in figure 2, sketch A at which its free end 15 engages the abutment surface 12. This prevents subsequent arcuate displacement of the mechanism 6 into the tablet-discharge position and ensures the shutter 8 closes off the orifice 30 leading into the chute 31 so that tablets cannot inadvertently drop out of the cassette.

When the cassette is stored separately from the apparatus and contains tablets, these are held in place by an upper lid 40 shown in figure 5, which fits onto the peripheral wall 18 of the chamber 16 of the cassette.

An underlid 41 shown in figure 4, can also be snap-fitted onto the underside of the cassette beneath the mechanism 6 so that the cassette and its contents are enclosed between the two lids. A shaped formation 42 integrally formed with the underlid 41, fits into the chute section 31 of the cassette to assist correct location of the underlid 41.

Operation of apparatus of preferred embodiment The cassette is used as follows.

A pharmacist or other user of the apparatus selects a particular cassette on the basis of the tablets it contains meeting the requirements of a doctor's prescription. If the apparatus is already loaded with a cassette containing the required tablets, it will have the correct combination of selector plate 21 and mechanism 6 fitted to it. On the other hand, if none of the cassettes stored by the pharmacist contain the required tablets, the pharmacist must take an empty cassette and fits to it the correct selector plate 21 and mechanism 6 in accordance with a table provided, and then load the required tablets into the well 13 of the cassette. The upper lid 40 is then placed over the chamber 1 6. The cassette is then transferred to one of the compartments of the apparatus and a decoder associated with the apparatus reads the identification code of the tablets which the pharmacist has placed on the side of the cassette.

When the apparatus of figure 1 is switched on, the tower of cassettes vibrate horizontally and rapidly through a small arcuate angle to cause the tablets in the cassette chambers to move outwardly and upwardly along the spiral tracks 17 to the discharge positions 20.

If two of the tablets in a cassette are superimposed upon one another or are at an incorrect angle to enter the pocket 26, the guide plate 25 deflects them back into the interior of the chamber. A tablet which has the correct orientation to enter the pocket 26 passes beneath the plate 25 and falls through the window 27 into the pocket 26.

When the cassette is placed into its compartment in the apparatus, the latch 11 in its underside is moved upwardly by a profiled part of the compartment and this frees the mechanism 6 for operation. The action of inserting the cassette into the chamber also

moves it into a position where a claw (not illustrated) fitted to the end of an actuating push rod associated with the compartment and referenced 400 in figure 1, locates around the pin 10 so that, when the push rod is reciprocated axially, its motion is imparted to the mechanism 6 in such a way as to cause it to reciprocate arcuately through a small angle around the vertical axis of the shaft 3.

Operation of the mechanism 6 causes a tablet in its pocket 26 to be conveyed from the tablet-loading position beneath the deflector plate 25, as shown in sketch"A"of figure 2, to the tablet-ejection position at which the side opening of the pocket 26 registers with the orifice 30, as shown in sketch"B"of figure 2. This occurs when the mechanism 6 is at the end of its arcuate stroke as shown in sketch B of figure 2, and the jolting of the tablet caused by the sudden reversal in direction of reciprocation of the mechanism 6, forcibly ejects the tablet through the orifice 30 and into the chute 31. The empty pocket 26 then returns to the tablet-loading position as shown in sketch"A"of figure 2, where it can receive the next tablet.

The arcuate reciprocation of the mechanism 6 takes place very rapidly and in a matter of a few milliseconds so that a high rate of discharge of tablets from the different cassettes occurs in accordance with a computer program controlling operation of a processor on the apparatus and which selects the push rods 400 which are to be operated to eject required tablets from the corresponding cassettes.