FR2640589A1 - Device for dispensing drops of small volume - Google Patents

Abstract

Device for dispensing liquid drops of small volume, comprising a cylindrical pump chamber 11e with one open end and having a wall at the other end, with a piston 12a sliding in a leaktight manner inside the said chamber, the piston being fastened to a rod 12b, sliding in a leaktight manner through an opening 11b of the wall of the pump chamber, characterised in that: the piston rod comprises a central channel 12d which emerges at its outer end 12k and is blocked at this end by a valve 14, the channel emerging laterally at the other end of the rod, in a radial passage 12e, at a location adjacent to the piston; the rod of the piston is long enough to allow the piston to leave the pump chamber; a spring returns the piston into the wall of the pump chamber; and means are provided for moving the piston against the force of the spring in order to make it leave the pump chamber.

Description

 The present invention relates to a device for dispensing drops of liquid of small volume, intended in particular, but not exclusively, for ophthalmological treatments. The finest standard dropper drops drops that are too large. 5 to 10 microliters (p1, or mm3) are enough to wash the surface of the eye. If a larger drop is deposited on the cornea, the excess passes into the cavities and onto the nasal mucosa. It is a loss, and furthermore it may be contraindicated. However, it is not currently possible to easily make such small drops. With a very fine dropper, the pressure of the fingers on the rubber pocket, even when acting carefully, drives out a large number of drops of very small volume. It currently seems difficult to deliver a drop so small, and n ' issue only one.

 It is an object of the present invention to provide a device which makes it possible to develop and deliver a drop of small volume, of the order of 10 mm 3 or less, and to deliver only one.

 The subject of the invention is a device for distributing liquid drops of small volume comprising a cylindrical pump chamber with an open end and having a bottom with a wall end, with a piston sliding in leaktight manner in said chamber, the piston being integral with a rod, sliding in leaktight manner in an opening in the bottom of the pump chamber, characterized in that: the piston rod comprises a central channel opening at its outer end and closed at this end by a valve, the channel opening laterally at the other end of the rod, by a radial passage, at a location adjacent to the piston; the piston rod is long enough to allow the piston to exit the pump chamber; a spring recalls the piston in the bottom of the pump chamber; and means are provided for moving the piston against the force of the spring to make it come out of the pump chamber.

 Advantageously, the device comprises a base, in the general shape of a washer, with a circular edge, a central hole of diameter equal to that of the piston rod, and on one face, around the hole, a skirt defining a pump chamber.

 Preferably, the device comprises a dispensing tip adaptable to the piston rod by snap-fastening, having an axial orifice calibrated in the axis of the piston rod, and defining with the end of the piston rod a volume for receiving a valve. elastically sealing the orifice of the axial channel of the piston rod.

 The invention also has a bottle on which is crimped a device of the type which has just been defined, as well as such a bottle housed in a casing advantageously designed to force users to rest the bottles of the invention upside down. : to avoid rising polluted liquids and to prevent defusing.

 Other characteristics and advantages of the invention will appear during the description which follows, given by way of nonlimiting example, with reference to the accompanying drawings, which will make it clear how the invention can be carried out.

In the drawings,
- Figure 1 is a schematic sectional view of a dispensing device according to the invention, set on a bottle, housed in a housing, the shape and function of which are part of the present invention;
- Figures 2 to 5 show in simplified section the mechanism of the device according to the invention, at different stages of operation; and
- Figures 6 to 8 each show in section one of the elements of the device of the present invention.

 An embodiment of the invention is shown in schematic section in Figure 1. The bottle is in the use position, the bottom in the air. We figured the level of the liquid in the bottle. It comprises an outer housing 1, with a cover 2 shown diagrammatically in broken lines. Inside is housed a bottle 3 made of glass or plastic on which is crimped a dispensing device 4 by means of a capsule 5. The crimping of the device on the bottle is shown without sealing washer. Depending on the material used to make the device, a washer may be preferable.

 The device is shown on a larger scale in Figures 2 to 5. It consists of five parts: a fixed part there (relative to the bottle) which will be designated below "base"; a movable assembly consisting of three parts, a piston 12, a dispensing nozzle 13, with a valve 14 in between; and a spring 15 holding the mobile assembly in a so-called rest position, relative to the base, shown in FIG. 2.

The base 11 has the general shape of a washer (see the section in FIG. 6). The outer edge I serves to fix the assembly on the neck of a bottle, and forms a sealing washer if it is molded in a suitable material, such as for example polyethylene. The base is drilled in the center of a hole 1 lob in which the rod 12b of the piston slides (see FIG. 7). As this sliding must be tight, the hole will be molded with precision, and the base may have on one edge, or both, of the hole
I lb, a circular sealing lip I Ic. The bottle thus closed has no air intake. The base has an I Id skirt on the outside of the bottle, useful for centering the capsule during assembly, and protecting the spring 15 and the piston rod 12b from dirt. On the face of the washer located towards the inside of the bottle, there is provided an island pump body also in the form of a skirt, opposite the first, having a sliding surface cooperating with the lateral surface 12c of the head 12a of the piston 12 This surface can be cylindrical as shown in broken lines In the example shown, this contact surface with the piston is reduced to a circular line il f of contact with a toric surface which seals against the piston. upper surface of the base (FIG. 6) a circular groove I Ig intended to promote molding.

 The piston (Figure 7) has a head 12a and a rod 12b, both of circular section, the rod being thinner than the piston. The diameter of the rod is equal to the diameter of the opening I lb of the base, so as to slide therein while ensuring the seal between the two sides of the base. The diameter of the piston head is equal to the diameter of the opening Il If of the pump body island formed on the upper face of the base. The piston head can thus slide in the pump body, while ensuring the seal between the two spaces separated by the contact surface. The piston rod has a blind longitudinal channel 12d extending from the end opposite the head (lower end) to the head. At this point, the channel 12d communicates with the outside via a passage 12e, opening through an opening 12f placed just under the head, and, as explained above, at a diameter smaller than that of the head, The opening 12g of the lower end is flared in one embodiment, and preferably placed in the center to form the 12 o'clock seat of the valve 14.

In the embodiment shown in the figures, the valve has two half balls connected by a spacer forming a fold. Thus, it is symmetrical, which only aims to facilitate the assembly of the device. Finally, the bottom of the piston rod 12k is formed with snap grooves 12m.

 Figure 8 is a sectional view of the distributor nozzle 13. It has a main tubular shape defined by a cylindrical wall 13a delimiting a cylindrical chamber 13b, designed to receive the lower end 12k of the piston rod 12. The part upper wall 13a is provided with one or more snap ribs 13c to cooperate with the grooves 12m of the piston. To make the two parts integral, the lower end 12k of the piston rod is introduced into the chamber 13b of the dispensing nozzle, and the pushing is carried out until the latching is obtained.

The piston rod is thus introduced after it has been passed through the central opening 11b of the base. All three parts: base, piston, distributor tip, are then inseparable. Care will have been taken to place the valve 14 in the bottom of the cylindrical chamber 13b, and to engage the spring around the piston rod, between the latter and the distributor nozzle. With the preferred form of valve, as shown, it automatically moves into the correct position. The set of five pieces is then inseparable, and ready to be mounted on a bottle.

 Towards the end of the chamber of the dispenser nozzle, opposite to that where the piston rod engages, a step 13d is formed, defining a fine channel 13e passing through the bottom of the chamber. On the outer face of the dispenser nozzle, the outlet 13f of the channel is surrounded by a prominence, so as to obtain a suitable diameter for the release of the drops. The total width L of the hole and the walls which surround it is defined as a function of the capillary properties of the liquid to be dispensed, and of the surface of the dispensing nozzle, as well as of the volume of each drop. For example, for a polyethylene dispensing nozzle, for water, and to have drops of 10 mm 3, the width L must be at most 0.7 mm.

 In order to facilitate the passage of the liquid, ribs 13m are formed on the bottom of the chamber 13b, on the step 13d.

 Finally, the dispensing nozzle has a second external cylindrical wall 13k, which has the purpose of serving as a support for the spring and of guiding it, of protecting it by cooperating with the skirt 1 Id of the base. The dimensions will be chosen (see Figure 2) so that there remains as little day as possible between the edges of the wall 13k and of the skirt 1 il, without interfering with the movement. Preferably, it is the wall 13k which enters the interior of the skirt 1 Id.

 The operation of the device according to the invention will now be described with reference to FIGS. 2 to 5.

The user wishes to evacuate a drop of liquid from the device shown in section in FIG. 1. In practice, taking into account the dimensions of the drops to be extracted, 10 mm 3, a fairly small container is required, otherwise the full use would require years, however ophthalmic products should not be kept more than 15 days after opening. The tank may therefore have a volume
on the order of 1 to a few cm3 (1 cm3 = 100 times 10 mm3). We will therefore understand that
the drawing of figure 1 is on a large scale (4 or 5 approximately). In an example
advantageous, the bottle has a volume of 1.5 cm3. It contains I cm3 of liquid and 0.5 cm3
of air.

To operate the bottle of Figure 1, it is necessary, after removing the
cap 2, turn the bottle upside down, and push the dispensing tip in relation to the
bottle. For this, we press with a finger (thumb or forefinger) on the bottom of the bottle,
and with two other fingers, press on the dispensing tip, preferably at
means of the housing 1, which gives more grip than the small dispensing nozzle. We
note that box 1, which is usually sold with the bottle, and stays on it
has no bottom, to allow access to the bottom of the bottle, but is advantageously
provided with at least one, here two diametrically opposite extensions la, lb,
separated by cutouts lc. Under these conditions, the bottle cannot be placed on
The bottom should be placed with the dispenser tip at the bottom, which is favorable for
prevent defusing. The housing 1 has a wall (la) with an orifice (lb)
to let out the end of the dispensing tip to allow insertion
this one.

For the rest of the operations, we will follow Figures 2 to 5, or only the device
is shown, without bottle or case. In these figures, the device is turned over, tip
dispenser down, the bottle is above.

A ~ the starting position (Figure 2), the head 12a of the piston bears against the edge
of the hole I lb of the base, in which hole the rod 12b of the piston is in sealed contact,
reinforced by the sealing lip I Ic. The hole 12f of the central channel of the piston rod
is opposite the cylindrical wall of the hole in the base. It is blocked. The device is
held resiliently in this position by the spring 15. The lateral surface 12c of the
piston is in tight contact against the edge 1 I f of the pump chamber.

If now we move the mobile assembly up (piston and distributor tip
with valve 14 interposed), the piston head slides into the pump chamber. On the
drawings, the piston-chamber contact is only ensured on a circular line, in view
simplicity of manufacture, assembly and operation, for a device
which is discarded after a few uses. The piston comes off from the base, and under the line of
contact, an annular chamber (C) is formed or a vacuum prevails (see Figure 2).

Indeed,;' the other end of the central channel 12d of the piston rod, the valve 14, in
plastic material molded in one piece, slightly compressed during assembly, presses elastically in the 12h flared opening of the channel. A depression is established
therefore in the volume formed by channel 12d and chamber C.

 Continuing the upward movement of the mobile assembly, the volume of the chamber C increases, the depression increases, until (FIG. 4) the piston head 12a takes off from contact with the island pump chamber. Due to the vacuum, the annular chamber C fills with liquid through the annular day between the piston head and the edge of the pump chamber, while the device reaches the end of the stroke, by contact of the upper edge 13r with the lower surface of the base, in the vicinity of the sealing lip 1 il. Nothing has yet come out of the dispensing nozzle.

The volume of chamber C, more precisely the volume of which it has increased during the stroke of the piston, is equal to the product of the section of the piston per stroke.

 The user then releases the pressure from the fingers, and the spring returns the mobile assembly to its rest position. Initially, the lower edge of the piston 12a engages in the flared opening of the pump chamber, and the volume of the annular chamber C becomes confined. Room C is closed (Figure 5). The mobile assembly continues its descent under the effect of the spring. The pressure rises in the volume of chamber C + channel. The pressure takes off the valve 14 from the flared opening of the central channel, and the volume of the chamber C is ejected through the channel 13e of the dispensing nozzle. Indeed, at the end of the stroke, the excess thickness of the piston is pressed against the base, the volume of the chamber C becomes zero. The ejected drop will peel off if the outside diameter L of the dispensing nozzle is small enough, as indicated above.

 In order to favor priming (to make it automatic), the dimensions will be defined so that the volume of channel 1 2d is less than that of chamber C.

The volume of chamber C is that of the drop that we want to drop. According to the invention, it will be between 5 and 25 mm3 and preferably between 5 and 10 mu3; if one chooses for the chamber C 10 mm3, it will be possible, for example, to easily create a channel of 7 mm3. During the first actuation, the chamber C will fill with 10 mm3 of liquid, and on evacuation by the dispensing nozzle, these 10 mm3 will completely expel the 7 mm3 of air. If you want a smaller chamber, 5 mm3, the volume of the channel will be limited to 3 or 4 mm3.

 The evacuation of the drop is controlled by the spring, therefore at a speed and under perfectly determined and chosen conditions. The drop is indeed chased during the return stroke towards the rest position. When the user presses on the device, nothing comes out of it. He cannot risk, by trembling (he holds the device a few centimeters from the eye and expects to receive a drop), to chase several drops.

 As there is no re-entry of air, the internal pressure in the bottle will drop gradually, and may be established at the end, for example around 0.5 atmosphere.

 Note also that the polluted volume below the valve is very small: a small fraction of a drop. The incentive to put the bottle upside down, thanks to the bumps 1a, 1b of the casing, prevents the liquid that is likely to be polluted from falling back into the bottle.

 Apart from the spring, the four parts can be made of plastic, chosen according to the product to be distributed: the same or not for the different parts (polyethylene, acetal resin, etc.).

 The product distributed is in no case in contact with a spring or any seal. The device therefore guarantees sterility. In addition, it can be radio-sterilized with a choice of materials.

 The distribution cannot be operated in a position different from that of the intended use. The shape of the base 11 could alternatively be produced so as to completely use the product to be used. There is no possibility of defusing.

 The distribution of very small doses makes it possible to carry out packaging of very reduced volumes, for example I cm 3 of product. This allows the device to be miniaturized. It is thus possible to use a more concentrated, more active product, which is sheltered from the air. It will contain less preservative, thus avoiding side effects in allergic subjects.

Claims (8)

Claims  1. Small volume liquid drop dispenser device comprising a cylindrical pump chamber (island) with one open end and having a bottom at the other end, with a piston (I 2a) sliding tightly in said chamber, the piston being integral with a rod (12b), sliding in leaktight manner in an opening (1 lb) at the bottom of the pump chamber, characterized in that: the piston rod comprises a central channel (12d) opening at its outer end (12k) and closed at this end by a valve (14), the channel opening laterally at the other end of the rod, by a radial passage (12e), at a location adjacent to the piston; the piston rod is long enough to allow the piston to exit the pump chamber; a spring recalls the piston in the bottom of the pump chamber; and means are provided for moving the piston against the force of the spring to make it come out of the pump chamber.  2. Device according to claim I, characterized in that it comprises a base (II), in the general shape of a washer, with a circular edge (1 la), a central hole (1 lb) of diameter equal to that of the piston rod, and on one side, around the hole, a skirt (island) defining a pump amber.  3. Device according to claim 2, characterized in that it comprises a distributor tip (13) adaptable to the piston rod by snap-fastening, having a calibrated axial orifice (13e) in the axis of the piston rod, and defining with the end of the piston rod a volume (13b) for receiving a valve (14) closing the orifice (l2g) elastically of the axial channel of the piston rod.  4. Device according to claim 3, characterized in that the dispensing nozzle (13) has an outer annular wall (13k) for holding and fixing a return spring.  5. Bottle equipped with a device according to one of the preceding claims, crimped onto the neck of the bottle (2).  6. Bottle according to claim 5, characterized in that it is wrapped in a box I leaving the lower surface of the bottle (2) unobstructed, but projecting laterally below it in at least one place (la, lb) , the housing having a wall (la) covering the bottle, with an orifice (lb) to allow at least the end of the dispensing nozzle (13) to pass through.  7. Bottle according to one of the preceding claims, characterized in that the pumped volume (C), equal to the product of the section of the piston by the stroke, is greater than the volumes added to the central channel (12d) and the radial passage (l2e) .  8. Bottle according to one of the preceding claims, characterized in that the volume delivered '(C) on each actuation is between 5 and 25 mm3 and preferably between 5 and 10 mm3.