CA2005928A1 - Device for dispensing a liquid or a cream in small-volume drops, and an associated dispensing assembly - Google Patents

Abstract

A B S T R A C T

The present dispenser device is designed in particular for eye treatment and comprises a pump body including a pump chamber, a piston slidable within the chamber and extended beyond the chamber by a rod pierced by a channel capable of communicating with the chamber, and an endpiece fixed to the rod and having a dispensing orifice in line with the channel of the rod. In addition to the above conventional items, the dispenser has a chamber admission valve which is constituted by co-operation between the enclosure defining the pump chamber and the piston which engages therein or projects therefrom as the case may be. The co-operation is preferably via a sealing lip. This disposition makes it possible to dispense a drop whose volume as determined by the capacity of the chamber is very small. In addition, the piston is returned to its rest position with the admission valve closed by resilient means disposed between the pump body and the endpiece. This guarantees that only one drop is dispensed at a time. Finally, an outlet valve is placed between the end of the channel in the rod and the dispensing orifice of the endpiece in order to ensure that a dispensed drop is slightly precompressed. The dispenser device is advantageously integrated in a dispenser assembly comprising a supply of substance to be dispensed together with handling means facilitating actuation of the assembly by a user. Some designs of assembly are particularly attractive, from the economic point of view, with respect to the process of being filled with the substance to be dispensed.

Description

A DEVICE FOR DISPENSING A LIQUID O~ A CREAM IN SMALL-VOLUME
DROPS, AND AN ASSOCIATED DISPENSING ~SSEMBLY
The presen-t inven-tion re}a-tes to an assembly con-taining a supply of a substance whose consistency may run from that of water or that of a cream, the assembly including a device for enabling the substance to be dispensed drop-by-drop. In addition, each drop corresponds to a small volume of about lO
microliters. Finally, the drop is eJeoted at a pre~sure which is slightly greater than atmospheric pressur~ so that it is possible to obtain a drop-dividing effect.
EAC~GROUND OF THE INVENTION
Such a dispensin~ assembly is par-ticularly advantageous for ophthalmological -treatments. This is because 5 to 10 microliters l~l or mm3) suffice for washing the surface of the eye. Even the finest of normal droppers deliver drops whose volume is -too great. As a result, excess liquid deposited on the cornea runs into cavities and over nasal mucus membranes. This constitutes a loss o active substance, and may even be counter-indicated~ The present invention therefore seeks to provide a device capable of genera-ting and delivering a drop of very small volume, about 10 n~l3 or less.
Anothsr aim of the invention is to provide a device that guarantees delivering only one drop at a time. The finest of presently-available droppers often suffer from the following drawback: they are difficult to operate, and if the user maintains pressure a little too long on a rubber ~ulb, for example, then a large number of drops are delivered almost simultaneously. This risk is increased when the user is in an uncomfortable position while operating the dropper, as is the case for eye treatments.
Finally, the present invention seeks to provide a dispensing assembly which includes not only a dispenser device having the above-mentioned qualities, but also a supply of substance commensurate wi-th the operation of the device. Given the very small volume of the drops dispensed, the supply must also be small in size. This gives rise to a problem in the ease with which the dispensing assembly can be handled.

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SUMMARY OF THE INVENTION
These various preoccupations are solved firstly by means of a dispenser device for dispensing a liquid or cream type substance in the form of small vol.uma drops, the device 5 comprising:
a puunp body having a pump chambar ormed the~ein with a bottorn wall and an enclosure whose end furthest from said bottom wall is open;
a piston adapted to engags inside said enclosure via said 10 open end and to slide in sealed manner therein between a high, admission position for admi-ttir~g sa~ d substanc::e into said chamber and a low, rest position, said piston being f ixed to a rod of smaller diame-ter whiah passes in sealed manner through said bo-ttom wall of said chamber and has a free end extend:ing 15 outside said pump body, said rod being pierced by a ct~ntra}
channel communica ting wi th a duat oE~ening out la terally benea th said piston;
an endpiece having a dispensing orifice and adapted to be fastened in sealed manner to said fres end of sald rod 20 exte~nding outside said pump body in such a manner that said central channel faces said orifica;
resilient means disposed between said pump body and said endpiece in order to return said piston to said low, rest position in which it comes into abu-tment against said bottom 25 wall of said chamber; and an outlet valve disposed batween said cantral channel of said rod and said dispensing orifice of said endpiece.
In a first variant of the present dispanser device, said enclosure flares from its opan end towards said bottom wall of 30 said chamber such that once said piston engaged in said enclosure, sealing contact is established around a line only, said duct opening out at the root of said piston~
Said enclosure may alternatively be a right cylinder, said piston being envelopad by a flexible cylindrical gasket 35 provided on its outside with an annular sealing lip directed towards said bottom wall of said chamber such that said lip co-opera-tes with said enclosure in order to delimit said pump 9,~

chamb~r, with at least one groove extending axially inside said enclosure from said open end down to a height such that said lip faces said at least one groove when said piston is in its high, admission position. In this case, said gasket advantageously has a bottom pierced by a hole adap-ted to receive said rod, said duct opening out laterally beneath said bottom of said gasket, and said gaske-t extending beyond said piston so that said gasket is firmly retained on said piston.
In this second variant, abutment means are disposed, where appropriate, between said pump body and said endpiece in order to limlt the stroke of said piston between its low, rest position and its high, admission position. It is also possible to provide for a flexible pocket to be fixed in sealed manner around said enclosure in order to receive a supply of said substance and protect it from the air. In which case, it :is advantageous for said enclosur~ to hava an ex-ternal annula:r thickening and for said pocket to have an opening with a reinforced edge, said opening being adapted to engage in a sealed fit around said enclosure.
Both in the first variant and in the second variant, said pump body preferably includes a sealing sleeve directed towards the outside of said body in order to bear against said rod passing through said bottom wall of said cha~ber. It may then ~e advantayeous for said pump body to be made of a plastic material whose flexibility is comparable with -that of low density polyethylene, said body also including a fine sealing lip directed towards the inside of said chamber in order to bear against said rod passing through said bottom wal-, said rod having an annular cut-out into which said lateral duct opens out.
For example, said endpiece may comprise a hollow tube having an open end, said free end of said rod being adapted to snap-fasten within said open end of said hollow tube. In this case, said outlet val~e may occupy the bottom of said hollow tube in said endpiece and may be constituted by two identical hemispheres with at least one flexible spacer extending therebetween, one of the hemispheres co-operating with the ~59~

opening of said central channel, and the other he~lisphere co-operating with said dispensing oriice.
Advantageously, said resilient means are constituted by a helical spring and said endpiece also includes an outer annular wall for holding and fixing said spring around said hollow tube.
In which case said high position of said piston i.5 advantage-ously determined by the said free end o said hollow -tube of said endpiece coming into abutment against said pump body.
However, it is equally advantageous for said resilient means to be constituted by a helical spring and said spring to be held around said hollow tube by radial partitions integral with said endpiece. In which case, said high position of said piston is advantageously determined by said radial partitions fixed to said endpiece coming into abutment against said p~unp body.
It may also be advantageous for said dispensing orifice to form a portion of a nozzle integrated in said endpiece.
Advantageously, the ma~imum volume of said pump chan~r, equal to the product of the section of said piston multiplied by its stroke, i.e. the distance between its high position and its low position, is greater than the sum oE the volume o~ said central channel and said radial duct o said rod. In which case the volume of a dispensed drop may lie in the range 5 mm3 to 25 mm3, and preferably in the range 5 min3 to 10 mm3.
The problems outlined in the introduction are also solved by a dispenser assembly including a dispenser device as out-lined above, wherein said pump body is crimped onto a flask which has a bottom and which encloses a supply of said substance protected from the air.
In another embodiment of the present dispenser assembly including a dispensing device as outlined above, said pump body ex-tends around said enclosure defining said pump chamber to constitute a receptacle which is open at its end furthest from said pump body in order to receive a supply of said substance protected from the air, said end of said receptacle being closed by closure means for forming a bottom on said dispenser assembly.

5g~,~3 In this case, said receptacle flares away from said enclosure to constitute a trunca-ted ~one such -that there exis-ts a minimum inside volume between said receptacle and said enclosure.
S St~ll with this other embodiment of the presen-t dispenser assembly, said closure means of said receptacle may be consti-tuted by a capsule which is crim~ed on after sald receptacle has been filled to abou-t one half its capacity with the substance. However, said closure means of said receptacle may alternatively b~ constituted by a snap-on cap, with an air vent being provided between said open end of said receptacle and said cap, and a scraper piston also being engaged in sealed manner inside said receptacle in order to separate said substance from the ambient air regardless of how full said lS receptacle may be.
In a further embodiment of the present dispenser assembly including a dispensing device as outlined a~ove, said pump body is adapted to receive in sealed manner and by snap-fastening a cartridge having a bottom and an open end opposite to said bottom, an air vent being provided through said bottom, a supply of said substance initially being contained inside said cartridge between a diaphragm closing said open end and a scraper piston disposed adJacent to said bottom, said piston also having a punch-forming fac~ suitable for puncturing said diaphragm on the first occasion said dispenser device is actuated.
For any of these various embodiments, a housing may receive said dispenser device toyether with said supply of substance, said housing being adapted to leave said dispensing orifice disengaged and also to leave said bot-tom disengaged, and being of such a shape as to enable a user applying two fingers of one hand against said housing to be able to press against said bottom with another finger of the same hand in order to actuate said dispenser device. Another solution may provide for said endpiece to extend around said rod of said piston in the form of a shell suitable for receiving said supply of said substance while leaving said bottom disengaged, ~5~

said shell including grasping means, -thereby enabling a user to apply two fingers o one hand thereagainst while pressing with another finger of the same hand agains-t said bottom so as to actuate said dispenser device.
In any event, it is advantageous for said bo-ttcm initially to comprise tear-of tamperproofing tongues projecting laterally in order to constitute an abutment for said supply and prevent said dispenser device being actuated.
BRIEF DESCRIPTION OF THE DRAWINGS
The following description refers to the accompanying drawings and relates to two variants of the dispenser device and four embodiments of the dispenser assembly, all given by way of non-limiting e~ample. In the accompanying drawings these examples are all shown at a scale considerably greater than lifesize. In the drawings:
Fi~ure 1 is an axial section thr~ugh a irst variant of the present dlspenser device in its rest posi-tion, and it i8 shown in association wi-th a first embodiment oE the present dispenser assembly Figures 2 to 5 are axial sections through the variant shown in Figure 1, with these figures showing only the dispenser device of the present invention and serving to illustrate different stages in the operation of the device;
Figures 6 to 8 are axial sections through respective components of the Figure 1 variant of the dispenser device of the invention;
Figure 9 is an axial section through a second variant of the dispenser device of the invention shown in its rest posi-tion;
Figure 10 is a detail of the section of Figure 9 but with the second variant of the dispenser device being shown in the high, admission position of the piston;
Figure 11 is a cross-section on a plane I-I of Figure 9 showing the second variant of the dispenser device as shown in the two preceding figures;
Figures 12 and 13 are axial sections through a second embodiment of the dispenser assembly of the invention shown t~9~

respectively with the piston in i-ts low, rest position and in its hi~h ~osition as reached when a user compresses the assembly to a maximum extent; and Figures 14 and 15 are axial sections respe~tively through a third and a fourth embodiment of the present assembly (shown each time in the rest posi-tion~.
In the various figures, parts or portions of parts that perform the same function are given identical reference numerals even if they are structurally different from one embodiment to another.
DETAILED DESCRIPTION
A first embodiment of a dispenser assembiy in accordance with the invention is shown in diagrammatic section in Figure 1. It comprises a flask 1' shown in its in-use position, bottom end uppermost. A liquid level can be seen inside the ~lask 1'. The 1ask is disposed in an outer housing 2' provided with a cap 6. The flask 1' is made of glass or plastia and has a first version of the dispenser devlce 10 crimped thereto by means of a ring 9. The crimping connection of the device 10 on the flask 1' is shown as having no sealing washer, however, depending on the material used for manu~acturing the device 10, it may be preferable to use a washer.
The device 10 is shown on a larger scale in Figures 2 to 5.
lt comprises five parts: a fixed part 1 (relative to the flask) referred to below as a "pump body"; and a moving assembly comprising three parts: a rod-piston 3; an endpiece 2; and a non-return valve 5 between them; and finally a spring 4 maintaining -the moving assembly in a "rest" position relative to the pump body, as shown in Figure 2.
The pump body is generally in the form of a hollow round part (see cross-section of Figure 6). Its outer rim 15' is used for fixing the dispenser device 10 to the neck of a flask, and it constitutes a sealing washer if it is molded in a suitable material, such as polyethylene, for example. The base of the pump body is pierced by a central hole 13' in which the rod-piston 3 is slidably mounted (see Figure 7). Since this sliding must be sealed, the hole is molded accurately, and one ~ ~ ~ S 94-~

or both edges of the hole 13 may be provided with a circular sealing lip 14. When sealed in this way, the flask does not include an air vent. The base of the pump body 1 has a skirt 12' on its face direc-ted away from the flask, the skirt being use~ul for centering the crimping ring during assembly, and serving to protec-t the spring ~ and the rod-pLston 3 from dirt.
An enclosure 11 is provided on the face of the body 1 facing towards the inside of the flask, wi-th the wall of the enclosure 11 being in ~he form of a skirt directed in the opposite direction to the skirt 12' and having a sliding surface adapted to co-operate, in this first variant of the dispenser device of the invention, directly with the side surface 31' of the head 31 of the rod-piston 3. This surface could be cylindrical as shown in dashed lines. However, in the example shown, the contact surface with the piston is reduced to a c:Lraular line of contact 11' on a toroidal surface which seals aga:Lnst the pis-ton. Thus, the enclosure 11 and the piston together define a pump chamber C. A circular groove 14' for facilitating molding is shown on the top surEace of the base of the pump body 1 (Figure 6)~
The rod-piston 3 (Figure 7) comprises a head 31 constituting the piston E~_ se and a rod 32, both of which are circular in section with the rod being smaller in diame-ter than the piston. The diameter of the rod is equal to the diameter o~ the hole 13' through the base of the body 1 so as to slide therein while providing sealing between the two sides of the base. The diameter of the head of the piston is equal to the diameter of the enclosure 11 formed on the top face of the base of the body 1. The piston head can thus slide in the enclosure while providing sealing between the two spaces separated by the contact surface. The rod of the piston has an axial blind channel 34 extending from its end furthest from the head (bottom end) to the head. At this point, the axial channel 34 communicates with the outside via a radial duct 35 opening out via an opening 35' placed immediately beneath -the head and, as explained above, of smaller diameter than the head. The opening 34' at the bottom end is advantageously flared and is t-~9~

preferably placed in the center of the rod in order to constitute a seat for the non-return valve 5. In the variant of the present dispenser device shown in Figures 1 to 8, the non-return valve comprises two half-balls interconnected by a zig-zag spacer. This makes it symmetrical, -thereby acilitating assembly of the dispenser device 10. Finally, the bottom of the rod 32 of the piston is formed with snap-fastening grooves 33.
Figure 8 is a section view through the endpiece 2. Its main shape is tubular, defined by a hollow tube 21 delimiting a cylindrical chamber 23' and designed to receive the bottom end 33' oi the rod-piston 3. The top portion of the inside wall of the hollow tube 21 is provided with one or more snap-fastening ridges 22 for co-operating with the groovas 33 of the rod-piston~ In order to fix these two parts to~ether, the bottomand 33' of the rod-piston 3 is inserted in~o the chamber 23' oE
tha endpiece 2, and is pushed home until snap-fastening occurs.
The rod-piston ls inserted in this way after being passed through -the cen-tral hole 13' in the base of the p~p body l.
The three-part assen~ly comprising the pump body, the rod-piston~ and the endpiece is then inseparable. The non-re turn valve 5 should previously have been placed in the bottom of the cylindrical chamber 23', and the spring 4 should have been placed around the rod-piston 3 between the rod-piston and the endpiece. When the non-return valve is of the preferred shape, as shown, it automatically takes up a correct position. All five parts are then inseparable. Toge-ther they cons-titute a dispenser device 10 of the inven-tion which is ready for mounting on a flask.
In the chamber 23' in the endpiece 2, towards its end furthest from the end into which the rod-piston 3 is engaged, there is a step 22' defining a passage 24' passing through the bottom of the chamber. On the outside face of the endpiece, the outlet 24 from the passage is surrounded by a projection 25 for obtaining an appropriate diameter for releasing drops. The total width L of the orifice 24 and of the annular chamfered projection 25 surrounding it is defined as a function of the capillary properties of the liquid to be disp~nsed and of the surface of the endpiece, and also as a function of -the desired voluma for each drop. By way of example, for an endpiece made of polyethylene, used for dispensing water, in drops having a volume of 10 mm3, the wid-th L should be not more than 0.7 n~.
In order to facilitate liquid emlssion, radial fluting 23 is provided in the bot-tom of the chamber 23' on the step 22'.
Finally, the endpiece includes an outer, second cylindrical wall 28' which provides an abut~nt and a guide for the spring, and which also serves, in co-operation with the skirt 12' on the base of the pump body, to protect the spring.
The dimensions are chosen (see F'igure 2) in order to ensure that there is as little clearance as possible between the edges of the wall 28' and of the skirt 12', while ensuring that the~
move freely. Preferably, the wall 28' penetrates into the skirt 12'.
The operation of this first embodiment of a dispenser assembly in accordance with the invention is now described with reference to Figures 2 to 5.
The user seeks to dispense a drop of liquid from the dispenser assembly shown in section in Figure 1. In practice, given the size of the drops to be dispensed, namely 10 mm3, the receptacle must be relatively small since otherwise it would take years to use up the substance contained therein.
Unfortunately, ophthalmological substances should not be kept for more than 15 days after the flask has been opened. The supply should -therefore have a volume of 1 to a few cubic centimeters (1 cm3 = 100 times 10 mm3). It will therefore be understood tha-t Figure 1 is drawn greater -than lifesize (about 4 to 5 times greater). In an advantageous example, the flask has a volume of 1.5 cm3, containing 1 cm3 of liquid and 0.5 cm3 of air.
In order -to operate the flask shown in Figure 1, the flask is turned upsidedown after removing its cap 6 and the endpiece 2 is then pressed towards the flask 1'. This is done by pressing with a finger (thumb or index finger) on the bottom of the flask and pressing with two other fingers on the endpiece, ~oor~g~

preferably via the housing 2' since it provides a larger area to grip than does -the small endpiece. It may be observed that the housing 2' which is normally sold with the flask and remains thereon, does not have a bottom, thereby leaving free access to the bo-ttom of ~he flask, and i-t is advantageously provided with at least one and preferably with two diametrically opposite e~tensions 2'a separated by cut-outs 2'b. They prevent the flas}c from being stood on its bottom, thereby ensuring that when it is put down, it is stood on its endpiece end, thereby making it more difficult to loose pump priming. The housing 2' comprises a wall ~'c having an orifice 2'd through which the end of the endpiece projects, thereby enabl~ng the endpiece to be pushed towards the flask.
For the following operations, reference is made to Figures 2 to 5 which show the dispenser device on its own without the flask and without the housing. In these figures, the device is directed downwards with its endpiece bottommost and with the flask above the device.
In the starting position (Figure 2) referred to below as the low, rest posltion, the head 31 o the rod-piston bears against the bottom wall of the ~lamber C on the edge of the hole 13' through the base of the pump body. The rod 32 of the rod-piston is received in the hole in sealing contact rein-forced by -the sealing lip 14. The opening 35' of the radial duct 35 in the rod-piston faces the cylindrical wall 12 of the hole 13 through the base, and is therefore closed. The device is held resiliently in this position by the spring 4. The side surface 31' of the piston head 31 is in sealing contact with the edge of the enc~osure 11 defining the pump chamber C.
If the moving assembly (rod-piston 3 and endpiece 2 together with the interposed non-return valve 5) is now raised, the piston head 31 slides within the pump chamber C. In the drawings, contact between the head and the enclosure is pro-vided only around a circular line 11' in order to facilitate the manufacture, assembly, and operation, of a device which is discarded af-ter being used a few times. The piston head comes away from the bottom wall of the chamber C, and the volume of 3t -the chamber C beneath the line of contact 11' increases, thereby satting up suction therein (see Figure 3). At the other end of the axial channel 34 along the rod 32, the integrally molded plas-tic non-return valve 5 which is slightly S compressed on assembly bears resiliently against the flared opening 34' of the channel. Suction is therefore established in the volume constituted by the channel 34, the radial duct 35, and the ch~nber C.
~y contl~uing -the upwards motion of the moving assembly, the volume of the chamber C i5 further increased, with suction therein also increasing, until the piston head 31 looses contact with the chamber 11 defining the pump chamber (Figure 4~. ~y virtue of the suction, the annular chamber C fills with liquid through the amlular opening between the piston head and the edge of the enclosure while the piston reaches the top end of its stroke (high, admission position) by virtue of the top edge 21' of the endpiece 2 coming into contact with the bo-ttom surface o -the base of the body 1, in the vicinity of -the sealing lip 14. At this poin-t, nothing has yet come out of the endpiece. The volume of the chamber C, and more precisely the increase in its volume during the stroke of the piston, is equal to the product of the section of the piston multiplied by the axial dista~ce betwPen the low, rest position of the piston and the high, admission position thereof.
The user then releases finger pressure and the spring returns the moving assembly towards its rest position.
Initially, the bottom ed~e of the piston head 31 engages in the enclosure 11 defining the pump chamber and the volume of the annular chamber C is confined. The chamber C is now closed (Figure 5). The moving assembly continues to move down under thrust from the spring 4. The pressure rises inside the volume constituted by the chamber C, the channel 34, and the duct 35.
This increased pressure lifts the valve 5 off the flared opening 34' of the axial channel, and the volume of the chamber C is ejected via the passage 24' of the endpiece. At the end of its stroke, the extra thickness of the piston bears against the bottom wall of the pump chamber whose volume -thus becomes 59,~

substantially zero. The ejected drop cQmes off if the outside diamete~ L of the endpiece orifice is small enough, as mentioned abova.
In order to facilitate pump priming (and ensure that it happens automatically), -the dimensions are defined so that the volume of the channel 34 is less than the voLume of the chamber C. The volume of the chan~r C is equal to the volume of the drop to be dispensed. In accordance with the invention, this volume should lie in the range 5 mm3 to 25 mm3, and preerably in the range 5 mm3 to 10 mm3. If the ~olume of the chamber C is selected to be 10 mm3, then there will be no difficulty in making a channel whose volume is 7 mm3. The first time the dispenser is operated, the chamber C fills with 10 mm3 of liquid, and on being evacua-ted via the dispenser endpiece, these 10 mm3 e~pel all of the 7 mm3 of air. If a smaller chamber is desired, e.g. 5 nn13, then the volume of ~hs ~hannel shoul~ be limited to 3 ~n3 or 4 mm3.
Drop expulsion is under the control of the spring, and therefore takes place at a speed and under conditions which can be accuratsly determined and selected. The drop is expelled during the return stroke towards the rest position. While the user is exerting pressure on the device, nothing comes out.
There is therefore no danger of several drops being ejected therefrom because the user is trembling ~given that the user is holding the apparatus a few centimeters away from the eye in order to receive a drop therein).
It may also be observed that the polluted volume benea-th the non-return valve is very small: a small fraction of a drop.
By encouraging the use to stand the flask head down, the two extensions 2'a on the housing prevent liquid tha-t may be polluted from running back into the flask.
IJnder no circumstances does the dispensed subs-tance come into contact with a spring or a sealing gasket of any kind.
The device thus guarantees sterile conditions. In addition, it may be radiation-sterilized if the materials from which it is made are suitably chosen.

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It cannot be made to dispense liquid in any position other than the design utilization position. As appears more clearly in th~ description of other ~nbodiments of the presen-t disp nser assen~ly, the shapa o th~ base of the pump bady can be formed in a variant sa as to use up all of the substance ~o be dispensedO There is no possibility of the pump becoming unprimed.
Ry dispensing very small doses of substance, it is possible to package the substance in very small volumes, e.g.
only 1 cm3 of substance. This means tnat the dispensing assembly can be miniaturized. It also means that the substance used can be more concentrated, more active, and protected from the air. It can contain less preservative, thereby avoiding secondary effects with people who are allergic.
It should be observed wi-th this first variant of the pre-sent dispenser device, tha-t there is no air vent. Con~equently the pressure inside the flask will gradually fall off, and may end up a-t around 0.5 atmospheres.
Apart from ths spring, the other three component parts of the present dispenser device (the pump body 1, the rod-pis-ton 3, and the endpiece 2) may be manufactured hy injection molding a pl~stic selected as a function of the substance to be dispensed and also of the particular function of each of the components. ~owever, when sealing is required between two parts that slide relative to each other, it becomes more difficult to find substances that satisfy these selection criteria. For example, in the pump body 1 it is desirable for the base to be relatively rigid in order to serve as an abutment for the spring 4, inter alia. However, it is also necessary to provide an enclosure 11 which is sufficiently flexible to bear closely agains-t the head 31 of the piston 3 and guarantee sealing contact all around the line 11'. In order to satisfy these two requiremen-ts which are, a priori, contradictory, a second variant of the present device is proposed. This variant is illustrated in Figures 9 to 11.
In particular, the axial sec-tion of Figure 9 shows that this varian-t differs from the preceding variant essentially by 9~

interposing a gasket 38 between the sliding surface 31' of the piston head 31 and the enclosure 11~ In order to facilitate assembly, the gasket 38 is in thP form of a hollow cylinder having a bottom pierced by a hole. It ls made of flexible plastic material ~Id is thus suitable for ~eing threaded onto the rod-piston 3, with the rod 32 being engaged in the hole.
The height of the corresponding cylinder is then designed so that once the bottom thereof is fi-tted to the root of the head 31, the cylinder proiects a little beyond the head. As a result, the flexible gasket 38 is firmly held on the piston 3.
It can then be seen that the resulting assembly operates in the same way as the preceding rod-piston providing the opening 35' of the radial duct 35 is moved away from the root of the head 31 in order to avoid it being obstructed by the gasket 38.
~he advan-tage of having such a gasket 38 is that by virtue of its shape and the material from which it is made it is easy to provide the gask~-t with a particularly e~eotive sealing llp 39. The lip 39 is directed towards the bottom wall of the pump chamb~r C so that in collaboration with the enclosure 11 it provides sealing which increases with increasing pressure inside the chamber. As a result, there ls no longer any need for the rod-piston 3 or the pump body 1 to be particularly flexible. The enclosure 11 can then be in the form of a relatively thick hollow cylinder projecting perpendicularly from the base of -the pump body. This makes ~t much easier to mold.
In this case, it is necessary to provide one or more axial grooves lla inside the enclosure ll (cf. the cross-section of Figure 11). These grooves lla run from the open end of the enclosure 11 and extend to a greater or lesser extent down the inside wall of the enclosure 11. This makes it possible to adjust the effective stroke of the piston in that the sealing provided by the lip 39 ceases to have any effect once the lip lies over the grooves lla. In other words, the volume of the chamber C that can be confined inside the enclosure 11 and which will give rise to a drop being expelled, is constituted merely by that po~tion of the volume of the enclosure 11 which ~O~

corresponds to its groove-free height. By varying the height of the enclosure which does not have grooves, it is possible to vary the size of the drops as dispensed.
This disposition means that the same pump body 1 can be S adapted to different sizes of drops to be dispensed, and it may be accompanied by additional measuxes for adapting the stroke o the piston. As can be seen in Figure 10 which shows the high positlon of the pis-ton, there ts n~ need, in this embodiment o~ the dispenser device, for the head 31 to move fully out ~rom the enclosure 11 in order to admit substance into the chamber C. On the contrary, the lip 39 must remain in contact wi-th the inside wall of the enclosure 11, but once it lies over a groove lla, the s-troke may be stopped. Adjustable-height abutment means (not shown) may be disposed for this purpose between the pump body and ths endpiece of -the disp~nser device.
Further, since i-t is now posslble to mold the pump body 1 and thus the enclosure 11 using a more rigid plastic material, an advantageous variant ma~ be developed. The enclosure 11 can then be used for fixing a pocket 9 over the top end o~ the dispenser device 10, with the poclcet b2ing constituted, for example, by a flexible elastomer membrane. To do this, the outside wall of the enclosure 11 is advantageously provided with an annular thickening llb whereas the pocket 9 ~visible only in part in Figures 9 and 10) has an opening 91 with a reinforced edge. Once this opening 91 has been passed over the enclosure 11, the resilience of the membrane constituting the pocket 9 will give a sealed connection and -the thickening will prevent the pocket 9 from sliding off. As a result, the supply of substance contained in the pocket is protected from air while remaining at atmospheric pressure regardless of the number of drops that have been expell~d. To make this possible, it suffices for the flask or housing (not shown) facilitating handling of the dispenser assembly to be fixed to the pump body in a non-sealed manner. Then, each time a drop is dispensed, air penetrates into the dispenser assembly and the pocket 9 shrinks. Where appropriate, other methods of )r~9~3 fixing the ~ocket 9 to the enclosure 11 may be used, e.g. snap-fastening, welding, heat sealing, ... .
In the detailed description below other variants of the various components of -the present dispenser device are men-tioned. Some of the features of these variants are alreadyshown in Flgures 9 to 11 described abova. Howeve~, the des~
cription of the dispenser device per se i9 now terminated in favor of describing ths assembly which, in -the present lnven-tion, comprises not only tha dispenser device but also a supply of substance to be dispensed and meau~ for making lt easy to handle. However, the person skilled in the art will understand that the various designs of pump body, endpie~e, rod-piston, enclosure, etc. can be interchanged to a greater or l~sser extent between the various embodiments described.
In some applications, the variants of the dispenser device 10 as desoribed above suffer from a drawback. They are designed to be associated with a flask which is mounte~ in sealed manner or otherwise to the pump body. In addition, a handling housing is necessary in order to facilitate actuating the device which is very small in size because of the small voluma of drops to be delivered. As a result, the dispenser assembly requires numerous operations during assembly by the manufacturer, and in particular:
1/ the flask must be filled;
2/ the pump body must be crimped onto the full flask; and 3/ the flask together with its pump needs installing in the handling housing.
When millions of dispenser assemblies are to be assembled in this way, these operations become a major drawhack economically speaking. It would therefore be advantageous to reduce the number of operations, even if only by one.
This is made possible by the second embodiment of a dispenser assembly of the present invention as shown in Figure 12. It comprises a receptacle 1 which is advantageously made of relatively fle~ible plastic material such as low density polyethylene. The receptacle 1 is in the form of a right cylinder of arbitrary height. At one of its ends the cylinder is open with its edge 18 preferably having an axially extending annular ridge 16. An annular groove 17 formed in the outside surface of the recep-tacle close to its edge 18 enables a capsule 7 (e.g. made of deformable metal) to be crimped around the edge 18, therehy closing the open end of the receptacle l in sealed manner.
At its opposite end, -the receptacle 1 preferably tapers in the form of a truncated cone 15. At the bottom of the truncated cone 15 a thic~ annular lip pro~ects into the receptacle. This lip constitutes the enclosure 11 for a pump chamber as in the previously-described variants of the device of the invention. However, in this case it forms a part of the receptacle 1 which now has -the pump bcdy integrally formed therewith. Concentrically with the enclosure 11 there is a hole passing through the bottom of the truncated cone 15. The wall 12 of this hole is advantageously provided with a very fine sealing lip 13 at lts end lnside the receptacle, and with a sealing sleeve 14 at its end outside the receptacle.
As in the structure of the variants described above, a rod 32 is passed -through the hole in order to slide therein in sealed manner. The rod 32 is also fixed to a head-forming piston 31. The cross-section of the piston head is sligh-tly greater than that of the rod in order to travel within the enclosure 11 while its sliding surface 31' remains in sealed contact with the enclosure 11. Like the first above-described varian-t, the enclosure 11 is somewhat flared at its base s-tanding on the bottom of the truncated cone 15. This reduces the contact area between the piston and the enclosure 11, thereby enhancing good sealing.
The rod 32 is pierced by an axial channel 34. This channel communicates with a duct 35 opening out sideways in the surface of the rod 32 immediately adjacent to the base of the piston head 31. In this embodiment, a small annular cut-out 36 is provided around the rod 32 level with the outlet from the duct 35 and extending along a height which is hardly any wider than said opening. Thus, the fine sealing lip 13 disposed on the wall 12 of the hole through the bottom of the receptacle 1 ~3l3t3~.:3 ~l9 is in no danger of being jammed in the opening of the duct 35 as the rod 32 moves up and down.
As in the ~irst embcdiment of -the present assembly described above, the free end of the rod 32 ls adapted to engage in a hollow tube 21 fixed to an endpiece 2~ To this end, the rcd 32 has a series of sharp projections 33 on its lateral surface, for example. These pro~eations then co-operate with a complementary series of grooves 22 in the inside surface of the tube 21 when the rod 32 is forced into the free e~d of the tube 21. At its other end, the tube 21 has a bottom pierced ~y an orifiae 24. Thus, between the bottom of the tube and the rod 32 there is a ahamber, and in similar manner to the first variant described above of the dispenser device, this chamber reaeives a small part 5 acting as a non-return valve.
This part is advanta~eously symmetrical in shape in order to faailitate ins-tallation thereof and is constituted, far example, by two hemispheres having one or more flexib:Le spacers disposed therebetween. One hemisphere is then disposed to close the channel 34 in the rod 32 and the other to close t:he orifice 24 of the endpiece 2.
As shown in Figure 12, the orifice 24 may be constituted merely by a hole through the bottom of the hollow tube 21 in the endpiece 2, together with radially disposed fluting 23 on the inside of the bottom, and an annular chamfered portion 25 set back in the outside surface. The advantage of this structure has also been descrihed. It is returned to below when describing the operation of this second embodiment of the present dispenser assembly. For the time being, it is merely recalled that various types of conventional nozzle (spray nozzle, flow-cutting nozzle, ...) can be fitted to the endpiece 2 over its orifice 24 in order to apply the present assembly to all sorts of utilizations.
The portion of the endpiece 2 described above already exists in the first embodiment shown in Fi~ures 1 to ll. In this second embodiment, this part is made integral with an outer ~hell 27 which also serves as a pushbut-ton. The bottom of the tube 21 extends laterally around the tube flaring 9~

smoothly until it completely surrounds the right cylinder of the recep-tacle 1. Ou-tside the shell 27 of the pushbutton/
endpiece 2 there is an outwardly projecting grasping ring 26.
Inside its flared length there are partitions 23. These partitions co-operate with the outside surfac0 of the tube 21 for guiding a return spring 4 disposed axlally between the pushbutton/endpiece 2 and the receptacle/body of the pump l.
Finally, a cap 6 is advantageously provided to be a forc -fit over the shell 27 of -the pushbutton/endpiece 2 for the purpose of protecting its orifice 24.
The dispenser assembly whose structure iæ described above is generally delivered to -the manufacturer of the substance to be dispensed, e.g. a pharmacQutical manufacturer, without its capsule 7. The manufacturer then pours substance into the receptacle/pump body 1 while the pump is pointing downwards.
It is preferable for the quan-tity of substance poured in in this way to be limited to one half the capacity o the receptacle. The~eater, the manufacturer crimps on the capsule 7 Wit}lOUt changing the orientation o the dispensing assembly.
After these two opera-tions only, the assembly is ready for delivery to the end user.
The user in question may be a patient who needs to administer the product one drop at a time. Some eye treatments require doses to be administered which are only just lar~e enough to spread over the surface of the eye, thereby avoiding any excess substance being eliminated via the tear duct. In this case, the user removes the cap 6 and holds the dispenser assembly be-tween three fingers, with the thumb and middle finger advantageously bearing against the ring 26 of the pushbutton/endpiece 2 while the index finger bears against the bottom of the capsule 7. The assembly is held with its orifice 24 pointing down.
Thereafter the dispenser assembly is operated in much the same manner as the first embodiment of the present invention.
When the user presses the receptacle/pump body 1 in-to the pushbutton/endpiece 2, the endpiece guides the recep-tacle, the return spring 4 is compressed and the rod-pis-ton 3 rises inside '3~

the receptacle. The piston 31 then tends to move out from the enclosure 11 defining the pump chamber C and the free space between the base of the piston 31 and the bottom of the truncated cone 15 increases. The opening of the duct 35 simultaneously disengagas the fine sealing lip 13. Assuming that the pump is primed, i.e. that the channel 34 is already ~ull of substance, the prassure o that ~ubstance ls reduced as the volume of the pump ch~nbar incx~a~es.
This continues until the receptacleJpump body 1 comes into abutment against the partitions 28 in the pushbutton/endpiece 2. The dispenser assembly is then in ~e position shown in Figure 13. It can be seen therein that in -this case the length of the rod 3~ is adjusted relative to the stroke of the receptacle l in the endpiece 2 in such a manner that the piston 31 escapes fully from the enclosure ll defining the pump chamber C. With the corresponding opening of the admission valve, the relative suction created in the pump chamber causes substance to be sucked into the pump chamber. Assuming that the enclosure 11 is immersed in the substance, the substance penetrates into -the chamber and fills it. It should be observed that during the events described above the non-return valve 5 remains closed and isolates all of the substance from the outside.
Then, when the user releases the force on -the receptacle, thereby allowing the return spring 4 to expand, the piston 32 re-engages inside the enclosure 11. By virtue of the seal which is re-established between the enclosure and piston, the admission valve is reclosed, and the pump chamber C is isolated again. Immediately thereafter, its volume constituted by the space inside the enclosure 11 between the base of the piston 31 and the bottom of the truncated cone 15 of the receptacle/pump body 1 begins to shrink. This increases the pressure of the product trapped inside the chamber. The flexibility of the lip 13 at tne bottom of the truncated cone 15 of the receptacle/pump body l prevents any of the substance from leaking under pressure between the wall 12 and the rod 32~
Indeed, the pressure in the chamber urges the lip 13 against the rod 32 over a relatively large area.

~ ~ C~j9~

During this transient s-tage, the opening of the duct 35 is unobstructe~ so the pressure of the substance is col~municated to the non-retun~ valve 5. Given the way the valve is de-signed, it opens for a pressure which is only slightly greater than atmospheric pressure. Even so thi~ suffices to guarantee that tha produot is emitted with a certain amount oE force.
Tha fluting 23 completes division of the product prior to it being expelled via the orifice 24 of the pushbutton/endpiece 2.
The chamfered snd 25 of the orifice 24 also ensures that the drop bec~nes detached as soon as the dimensions described relative to the first ~mbodiment of the present dispenser assembly are satisfied.
That is how the rest posi-tion shown in Figure 12 is rapidly re-established. The volume of liquid e~pelled by the dispenser device sets up or increases suction in the receptaale. In practice this is not particularly lnconvenient in that a sufficiently large quantity o~ air is present initially tin general about half its capacity). In this case, emptying the receptacls leads to a inal pressure of about half a bar and this is perfectly compatible with overall sealing of the receptacle, given that it has a sleeve 14. Thls pressure difference is insufficient to lift the enclosure 11 off the piston 31 or to lift the lip 13 off the opening to the duct 35.
As a result the channel 34 remains filled with liquid so that next time the device is operated a drop is properly delivered.
However, in order to provide greater security, particularly once the dispenser assembly has aged somewhat, the lip 13 is maintained in a curved position against -the base of the piston 31 when the device is in its rest position. The creep to which the lip is subjected over time therefore tends to provide sealing which is increasingly effective.
However, priming -this second embodi~ent as described above requires pump chamber dimensions to satisfy conditions, as for the first embodiment. The first time the device is actuated, with the channel 34 s-till filled with air, less suction is established in the chamber C. After its admission valve has opened, it is filled mostly under gravity and air is not 2~
~3 expell~d to any great ex-tent fr~n the channel 34. Priming is therefore possible only if the maximum content of the chamber is sufficiently large relative to the content of the channel.
In practice this sets a bottom limit on -the size of drops dispensed to around 5 microliters. Below this value, the air init~ally oontained in ~h~ channel 34 can compress to provide room for the substance coming from -the pump chan~er wlthout establishing sufficient excess pressure to open the outlet valve 5.
~owever, in the context o the present invention, this limitation can be overcome. The dispenser assembly as shown in Figures 12 and 13 may be filled while the admission valve is open. The manufacturer of the li~uid doeæ this by disposing the assem~ly in a recep-tacle which keeps the return spring 4 compressed. Whlle the piston 31 remains disengaged from the enclosure ll in this way, substance enters the channel 34 and remains trapped therein as soon as the spring 4 is rela~ed again. However, i-t is nevertheless necessary to ensure that ~he receptacle/p~np body 1 is filled with substance under a small ~nount of pressure in order to ensure that the air initially present in the channel 3~ is expelled, unless the channel is large enough for capillary tension effects to be avoided.
A third embodiment of the present dispenser assembly is shown in axial section and in the rest state in Figure 14. It differs from the preceding assembly in its system for closing the receptacle/pump body 1. This time, the substance to be dispensed is enclosed therein without air, and a scraper piston 8 is used to close the open end of the receptacle. A cap 7 is snap-fastened over said end and the rim 18 of the end includes notches 19 for admitting air. Thus, a thrust surface is provided for actuating the dispenser assembly while the scraper piston 8 moves further and further into the receptacle as it is emptied. This means that it is no longer essential to keep the pump at the bottom of the dispenser assembly in order to ensure that a drop of substance is ejected.

;~ ~ O ~ r4~ ~3 2~L

This third embcdimen-t is advan-tageous when the substance to be dispensed needs -to be kept separate from the air in order to avoid chemical damage, etc. However, compared with the second assembly described above, it leads to a larger quantity of substance being lost. When the scraper piston 8 comes ~nto contact with the piston 31, the dispenser device can no lon~er be actuated. Thus, any substance remaining around the piston 31 cannot be extracted from -the receptacle. If there were no scraper piston 8, then the substance could be extracted from the pump until the liquid level drops below the edge of the enclosure 11. The truncated cone shape 15 of the receptacle/
pump body 1 also serves to reduce the quantity of substan~e remaining in the dead vol~ne to a minimum. To the same end, it is possible to give the scraper piston 8 a shape which is complementary to that of the piston 31.
In the last -two embodiments described above, tamper~
prooing tongues 18' can be molded on the receptacle/pump body 1 as shown in Figure 14. Although easily sheared off, these tongues 18' withstand compression well. Thus, until a user tears them o~f deliberately, they prevent the dispenser assembly being used by providing an abu~nent for the pushbutton/endpiece 2. Similarly, they make it much easier for the manufacturer of the substance to ba dispensed to crimp on the capsule or snap on the cap.
Finally, it will be understood that the heigh-t of the receptacle 1 and its endpiece 2 are arbitrary, a priori. In particular, it would be quite possible for the receptacle to be pipette-shaped.
A fourth and last embodiment of the present dispenser assembly in shown in axial section in Figure 15. Apart from one or two minor modifications, its moving parts (reference numerals 2 to 6) are identical to those of the second and third embodiments of Figures 12 to 14. Its novelty lies in the supply of substance. In this case, the supply is in the form of a cylindrical cartridge 1 having one end 16' which is both closed by a diaphragm 9 and provided with lateral projections for snap-fastening purposes. The opposite end of the cartridge 1' is in the *orm of a bottom. However, the botto~ is pierced by an air inlet hole 19'. I-t may also be provided with a tear-off tamperprooing tongue 18' projecting locally from its periphery. Similarly, a lateral safety tab 17' may be provided. Inside the cartridge 1' there may be a scraper piston 8 for hermetically isolating the substance to be dispensed from ambient air.
It will be understood how the manufacturer of the sub-stance to be dispensed finds such a cartridge l constitutes an advantage for packaging purposes. To begin with the scraper piston 8 is placed inside an empty cartridge. This is generally easier to do than inserting a piston over the sub-stance and then crimping on a capsule or snapping on a cap as required by the thixd embodiment described above (cf~ Figure 14). Thereafter, the substance is poured into the cartridge 1'. Finally a diaphragm 9 is applied to the open end 16' of the cartridge. This operation may be performed by heat sealing, for example, but other methods o~ closing the end 16' by a diaphragm 9 are also possible. Theraafter, the ~illed cartridge 1' is easily snap-fastened in a pump body 1 as des-cribed above with respect to the second embodiment of the pre-sent assembly, for example. ~o do this, it su~fices ~or the pump body 1 to have an edge 15' provided with an annular groove 14' for co-operating with the snap-fastening projections at the end 16' of the cartridge 1'. It is nevertheless important that the snap-fastening should provide adequate sealing.
The end user uses this fourth embodiment of the present assembly in the same way as the preceding embodiments. The tamperproofing tongue 18' is torn off and the cap 6 is removed.
Then, e.g. using the index finger, the accessible end of -the cartridge 1' projecting from the endpiece 2 is pressed down.
Providing the lateral safety tab 17' is indeed disposed facing a notch 29 formed in the endpiece 2, the spring 4 can then be compressed and the moving parts of the assembly (i.e. the endpiece 2, the rod-piston 3, and the non-return valve 5) are displaced relative to the pump body 1. ~s described in greater detail above, the piston head 31 moves out from the enclosure ~ ~ ~5 ~

11 de~ining the punlp chan~er C. The top of the head 31 is deliberately shaped as a punch in this embodiment and it bursts the diaphragm ~. The substance then spreads into the pump body 1 and penetrates into the enclosure 11 while the air initially trapped in the body 1 rises beneath tha scraper piston 8.
So long as the relative s~zes of ths chamber C at its gre~atest extent and of the axial channel 34 and the radial duct 3S specified above are satisfied, then tha di~panser device of the invention will prime. As the substanca is dispensed, the scraper piston 8 n~ves down inside the cartr~dg~ 1' with air admitted via the hole 19' compensating for the drops of substance dispensed. Each time the device is actuated, it is advantageous for the user to rotate the cartridge 1' a little relative to the shell 27 of the endpiece 2. This moves the lateral safety tab 17' away from the notch 29, thereby preventing relative axial movement between the vario~ls parts constituting the dispenser assembly of the invention.
Numerous other variants will appear to the person skilled in the art depending on the intended application and without thereby going beyond the scope of the present invention as specified by the followiny claims.

Claims (27)

1/ A dispenser device for dispensing a liquid or cream type substance in the form of small volume drops, the device comprising:
a pump body having a pump chamber formed therein with a bottom wall and an enclosure whose end furthest from said bottom wall is open;
a piston adapted to engage inside said enclosure via said open end and to slide in sealed manner therein between a high, admission position for admitting said substance into said chamber and a low, rest position, said piston being fixed to a rod of smaller diameter which passes in sealed manner through said bottom wall of said chamber and has a free end extending outside said pump body, said rod being pierced by a central channel communicating with a duct opening out laterally beneath said piston;
an endpiece having a dispensing orifice, and adapted to be fastened in sealed manner to said free end of said rod extending outside said pump body in such a manner that said central channel faces said orifice;
resilient means disposed between said pump body and said endpiece in order to return said piston to said low, rest position in which it comes into abutment against said bottom wall of said chamber; and an outlet valve disposed between said central channel of said rod and said dispensing orifice of said endpiece.

2/ A dispenser device according to claim 1, wherein said enclosure flares from its open end towards said bottom wall of said chamber such that once said piston engaged in said enclosure, sealing contact is established around a line only, said duct opening out at the root of said piston.

3/ A dispenser device according to claim 1, wherein said enclosure is a right cylinder, said piston being enveloped by a flexible cylindrical gasket provided on its outside with an annular sealing lip directed towards said bottom wall of said chamber such that said lip co-operates with said enclosure in order to delimit said pump chamber, with at least one groove extending axially inside said enclosure from said open end down to a height such that said lip faces said at least one groove when said piston is in its high, admission position.

4/ A dispenser device according to claim 3, wherein said gasket has a bottom pierced by a hole adapted to receive said rod, said duct opening out laterally beneath said bottom of said gasket, and wherein said gasket extends beyond said piston so that said gasket is firmly retained on said piston.

5/ A dispenser device according to claim 3, wherein abutment means are disposed between said pump body and said endpiece in order to limit the stroke of said piston between its low, rest position and its high, admission position.

6/ A dispenser device according to claim 3, wherein a flexible pocket is fixed in sealed manner around said enclosure in order to receive a supply of said substance and protect it from the air.

7/ A dispenser device according to claim 6, wherein said enclosure has an external annular thickening and wherein said pocket has an opening with a reinforced edge, said opening being adapted to engage in a sealed fit around said enclosure.

8/ A dispenser device according to claim 1, wherein said pump body includes a sealing sleeve directed towards the outside of said body in order to bear against said rod passing through said bottom wall of said chamber.

9/ A dispenser device according to claim 8, wherein said pump body is made of a plastic material whose flexibility is comparable with that of low density polyethylene, said body also including a fine sealing lip directed towards the inside of said chamber in order to bear against said rod passing through said bottom wall, said rod having an annular cut-out into which said lateral duct opens out.

10/ A dispenser device according to claim 1, wherein said end-piece comprises a hollow tube having an open end, said free end of said rod being adapted to snap-fasten within said open end of said hollow tube.

11/ A dispenser device according to claim 10, wherein said outlet valve occupies the bottom of said hollow tube in said endpiece and is constituted by two identical hemispheres with at least one flexible spacer extending therebetween, one of the hemispheres co-operating with the opening of said central channel, and the other hemisphere co-operating with said dispensing orifice.

12/ A dispenser device according to claim 10, wherein said resilient means are constituted by a helical spring and wherein said endpiece also includes an outer annular wall for holding and fixing said spring around said hollow tube.

13/ A dispenser device according to claim 12, wherein said high position of said piston is determined by the said free end of said hollow tube of said endpiece coming into abutment against said pump body.

14/ A dispenser device according to claim 10, wherein said resilient means are constituted by a helical spring and wherein said spring is held around said hollow tube by radial partitions integral with said endpiece.

15/ A dispenser device according to claim 14, wherein said high position of said piston is determined by said radial partitions integral with said endpiece coming into abutment against said pump body.

16/ A dispenser device according to claim 1, wherein said dispensing orifice forms a portion of a nozzle integrated in said endpiece.

17/ A dispenser device according to claim 1, wherein the maximum volume of said pump chamber, equal to the product of the section of said piston multiplied by its stroke, i.e. the distance between its high position and its low position, is greater than the sum of the volume of said central channel and said radial duct of said rod.

18/ A dispenser device according to claim 1, wherein the volume of a delivered drop lies in the range 5 mm3 to 25 mm3, and preferably in the range 5 mm3 to 10 mm3.

19/ A dispenser assembly including a dispenser device according to claim 1, wherein said pump body is crimped onto a flask which has a bottom and which encloses a supply of said substance protected from the air.

20/ A dispenser assembly including a dispenser device according to claim 1, wherein said pump body extends around said enclosure defining said pump chamber to constitute a receptacle which is open at its end furthest from said pump body in order to receive a supply of said substance protected from the air, said end of said receptacle being closed by closure means for forming a bottom on said dispenser assembly.

21/ A dispenser assembly according to claim 20, wherein said receptacle flares away from said enclosure to constitute a truncated cone such that there exists a minimum inside volume between said receptacle and said enclosure.

22/ A dispenser assembly according to claim 20, wherein said closure means of said receptacle are constituted by a capsule which is crimped on after said receptacle has been filled to about one half its capacity with the substance.

23/ A dispenser assembly according to claim 20, wherein said closure means of said receptacle are constituted by a snap-on cap, with an air vent being provided between said open end of said receptacle and said cap, and a scraper piston also being engaged in sealed manner inside said receptacle in order to separate said substance from the ambient air regardless of how full said receptacle may be.

24/ A dispenser assembly including a dispenser device according to claim 1, wherein said pump body is adapted to receive in sealed manner and by snap-fastening a cartridge having a bottom and an open end opposite to said bottom, an air vent being provided through said bottom, a supply of said substance initially being contained inside said cartridge between a diaphragm closing said open and and a scraper piston disposed adjacent to said bottom, said piston also having a punch-forming face suitable for puncturing said diaphragm on the first occasion said dispenser device is actuated.

25/ A dispenser assembly according to claim 19, wherein a housing receives said dispenser device together with said supply of substance, said housing being adapted to leave said dispensing orifice disengaged and also to leave said bottom disengaged, and being of such a shape as to enable a user applying two fingers of one hand against said housing to be able to press against said bottom with another finger of the same hand in order to actuate said dispenser device.

26/ A dispenser assembly according to claim 19, wherein said endpiece extends around said rod of said piston in the form of a shell suitable for receiving said supply of said substance while leaving said bottom disengaged, said shell including grasping means, thereby enabling a user to apply two fingers of one hand thereagainst while pressing with another finger of the same hand against said bottom so as to actuate said dispenser device.

27/ A dispenser assembly according to claim 25, wherein said bottom initially includes tear-off tamperproofing tongues projecting laterally in order to constitute an abutment for said supply and prevent said dispenser device being actuated.