Abstract:
A dispensing apparatus for a liquid product, the apparatus comprising a) a housing ( 2 ) or frame ( 3 ), b) a receptacle ( 4 ) for the liquid with a feed nozzle ( 4   a ) arranged substantially stationary with respect to the housing or frame, c) a dosing chamber ( 11 ) having an orifice ( 11   a ), d) a mechanism arranged to allow at least ejection of liquid through the orifice and e) a through passage ( 7 ) arranged to allow the ejected liquid to pass in a direction different from the feed nozzle or opening. The mechanism comprises a mobile element arranged movable with respect to the housing or frame between at least a first position in which the orifice of the dosing chamber and the feed nozzle or opening are in flow communication and a second position in which the orifice and the through passage are in flow communication and the mechanism is arranged to allow aspiration of liquid through the orifice when the mobile element is in the first position and ejection of liquid through the orifice when the mobile element is in the second position. A method for operating the device comprises the steps of i) connecting the orifice and the nozzle or opening in flow communication, ii) filling liquid into the dosing chamber through the orifice, iii) aligning the orifice with the through passage, and iv) ejecting liquid from the dosing chamber through the orifice.

Description:
RELATED APPLICATION 
   The present application claims priority under 35 U.S.C. §119 of U.S. application Ser. No. 60/415,015 filed Oct. 1, 2002. 

   FIELD OF THE INVENTION 
   The present invention concerns a dispensing apparatus for liquid products, particularly medicinal products, such as an ophthalmic solution. 
   BACKGROUND OF THE INVENTION 
   Although the principles of the present invention may have utility in many areas, for convenience it will be described mainly in connection with liquid treatment of eyes. Typically the medical preparation has to be delivered in a fairly well defined volume to assure a specified dose to be delivered or absorbed. A large surplus cannot be allowed due to improper systemic physiological effects from absorbency in non-target tissues or drainage of excess amounts through the tear channel into the throat cavity or the inconveniences caused by overflow on face and clothes. Also price considerations apply for expensive medications. As an example, the treatment of glaucoma requires frequent daily administrations of e.g. prostaglandins, beta-blockers or other expensive active ingredients, all having other then the desired pressure relieving action when absorbed by other body tissues than the eye. Small volume dosing is negatively affected by even small uncontrolled or dead spaces in delivery equipments used. Moreover, medical preparation components may be sensitive to degradation or absorption at prolonged exposure to materials and extended surfaces present in delivery devices. Similar considerations apply for sterility preservation. With regard to stream quality, proper administration of small amounts is complicated by the fact that the active ingredients cannot enter the eye but through the limited area of the cornea. It is also necessary that the entire dose can be delivered before the triggered blink reflex closes the eyelid. 
   A large number of devices are already known for applying a determined quantity of a liquid medicinal product onto a part of the body, such as an ophthalmic solution on the surface of the eye. These devices generally rely on the principle of a syringe which can be either pre-filled with a determined quantity of liquid, or graduated to suck up said quantity of liquid contained in a separate bottle, or connected to a fixed receptacle in permanent communication with the dosing chamber of the syringe, as is described for example in one of the embodiments of U.S. Pat. No. 4,623,337. It will be observed that permanently feeding the dosing chamber from the receptacle via gravity means that neither the precision of the quantity of liquid to be ejected, nor the sterility thereof can be guaranteed. In these devices, the pressure exerted on the plunger, manually or automatically, is generally exerted in the same direction as that of the liquid jet, as is described for example in International Patent Application No. WO 92/20455. 
   The direction of the jet can sometimes be deviated by bent conduits, but it is then difficult to control the force with which the jet reaches its target. A device of this kind is like, for example, that disclosed in French Patent No. FR 2 647 757 for food products or cosmetics in liquid or paste-like form, for which respecting a given ejection pressure is of no importance. 
   In the case of a an ophthalmic solution, it is, however, very important not only to control very precisely the dose to be ejected for obvious reasons of safety and efficacy of the treatment, but also in order to be able to control the impact pressure of the liquid jet on the eye, which certain devices attempt to achieve by using an eyepiece or a spacing member applied to the periphery of the target to impose a fixed distance with respect to the liquid ejection orifice, as is disclosed for example in U.S. Pat. Nos. 4,623,337 and 5,836,911. It will be observed however that these devices do not always allow the impact force of the liquid jet to be reproduced when the pressure is exerted directly on the plunger manually. 
   Thus, the dispensing apparatuses of the prior art provide individual solutions to particular problems, but none of them allows all of the aforementioned problems to be simultaneously resolved. 
   SUMMARY OF THE INVENTION 
   The object of the present invention is thus to provide a dispensing method and device capable of avoiding the problems discussed above. More particularly an object is to provide a method and device system capable of ejecting, e.g. with a new design of the plunger head leaving practically no ullage, a precise dose of liquid, such as an ophthalmic solution, with an adjustable impact pressure on the target and the dose and impact pressure being independent of the way in which the pressure is exerted on the actuator. The apparatus according to the invention includes a mechanism allowing sterility conditions to be improved, given that the receptacle is only in communication with the dosing chamber except for a brief moment during ejection when it is placed in communication with the external environment for a few tenths of a second, during which time the pressure equilibrium is achieved by replacing the sucked up liquid with air. In addition the system allows uncontrolled and a dead spaces to be kept to a minimum. The apparatus is further very easy to use in particular for an ophthalmic solution. 
   These and other objects are reached by the characteristics set forth in the appended patent claims. 
   The movement of the actuator is preferably substantially perpendicular to the direction of ejection of the liquid, such that the pressure exerted on the actuator cannot modify the distance with respect to the target, for example the eye in the case of an dispensing ophthalmic solution. 
   According to a first embodiment, the mobile element is formed by a drum provided, on its flanks, with studs rotatably mounted in the two shells of the housing, and housing in its diametral part an assembly formed by the dosing chamber, the plunger and the return spring. 
   At the start of pressure on the actuator, the drum occupies a first filling position in which the orifice of the dosing chamber is opposite the receptacle feed nozzle. By continuing to press on the actuator, the drum rotates through an angle α to occupy a second ejection position in which the orifice of the dosing chamber is opposite the through passage of the housing. 
   In a second embodiment, the dosing chamber is formed in a unit secured to the frame, and the mobile element is formed by a mobile valve, held in the rest position by a return spring. At the start of pressure on the actuator, the valve occupies a first position for filling the dosing chamber through a channel formed in the thickness of said valve placing the orifice of the dosing chamber in communication with the receptacle nozzle. By continuing to press on the actuator the valve is brought into a second ejection position in which the orifice of the dosing chamber is placed in communication with the exterior through a hole of the valve located opposite the through passage of the frame. 
   In both embodiments, the actuator is returned to the rest position by resilient return means, wound by the travel of the plunger during the filling and ejection phases. In these two embodiments, in order to further increase the conditions of sterility, the actuator can include a panel blocking the through passage of the housing or frame from the exterior in the rest position, said panel including an orifice brought to face said through passage in the ejection position. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     Other features and advantages of the present invention will appear more clearly upon reading embodiment examples, given purely by way of non-limiting illustration, with reference to the annexed drawings, in which: 
       FIG. 1  shows a perspective view of a dispensing apparatus according to the invention without the external cover; 
       FIG. 2  shows a cross-section of the apparatus of  FIG. 1 , along the arrows II—II parallel to the base of the apparatus; 
       FIG. 3  shows an exploded perspective view of the apparatus of  FIG. 1 ; 
       FIG. 3A  shows an enlarged diagram of the pinion and pins shown in the exploded perspective view of  FIG. 3 ; 
       FIG. 4  shows a side view of the apparatus of  FIG. 1  in which one shell of the housing and the drum have been removed; 
       FIG. 5  shows a cross-section along the line V—V of  FIG. 2 , of the mechanism assembly in the rest position; 
       FIG. 6  corresponds to the suction phase of a determined quantity of liquid to be ejected; 
       FIG. 6A  shows an enlarged diagram of the pinion and return rack shown in the liquid suction phase of  FIG. 6 ; 
       FIG. 7  corresponds to the rotation of the drum to the ejection position; 
       FIG. 7A  shows an enlarged diagram of the pinion, pins and holes shown in the drum of  FIG. 7 ; 
       FIG. 8  corresponds to the liquid ejection phase; 
       FIG. 8A  shows an enlarged diagram of the pinion and rack shown in the liquid ejection of  FIG. 8 ; 
       FIG. 9  shows a position of the drum during the return to its rest position; 
       FIGS. 5A to 9A  show the different positions of the drive members in the phases corresponding to  FIGS. 5 to 9 ; 
       FIG. 10  shows a side view of a second embodiment of the invention; 
       FIG. 11  is a cross-section in the plane of symmetry of the apparatus shown in  FIG. 10  in the rest position; 
       FIG. 12  is an exploded perspective view of the apparatus shown in  FIG. 10 ; 
       FIGS. 12A and 12C  are enlarged diagrams of two elements of the mechanism from another angle; 
       FIG. 12B  is a cross-section of another element of the mechanism; 
       FIG. 13  corresponds to the suction phase of a determined quantity of liquid; 
       FIG. 13A  is an enlarged diagram of the valve during the liquid suction phase; 
       FIG. 14  shows the phase during which the valve passes into the liquid ejection phase; 
       FIG. 14A  is an enlarged diagram of the valve during the liquid ejection phase; 
       FIG. 15  shows the liquid ejection phase; 
       FIGS. 16 ,  17 ,  18  show the return of the apparatus to the rest position; and 
       FIGS. 19 ,  19 A and  20  respectively show in the rest position and at the end of ejection a variant illustrated with the second embodiment. 
   

   DETAILED DESCRIPTION 
   In  FIG. 1 ,  FIGS. 1 and 10  show, in perspective, two embodiment examples of a dispensing apparatus according to the invention. In  FIG. 1 , the apparatus includes an external cover  1  marking the mechanism of a second embodiment which will be described hereinafter where the external cover has been removed, one can see that externally the apparatus includes a housing  2  formed of two shells  2   a ,  2   b  assembled by a screw  2   c  after positioning the contact surfaces by means of pins  2   d  visible in the exploded view of  FIG. 3 , to which reference will also be made in the description hereinafter. The liquid, which will have to be ejected from the apparatus in the direction of double arrow L, is contained in a receptacle  4  which, in this example, is a bottle ending in a feed nozzle  4   a . Bottle  4  is secured to the apparatus by means of an adjustable clamp  5 , to shells  2   a ,  2   b  by means of screws  5   a . In  FIG. 1 , it can also be seen that actuator  30 , the actuation of which by a force F is effected in a substantially perpendicular direction to the direction of ejection of the liquid. In this embodiment, the actuator take the form of a push button and is generally U-shaped with a head  32  extended by two branches  34   a ,  34   b , the construction and functions of which will be described hereinafter. 
   Reference will also now be made to  FIG. 4 , in which external cover  1  has been kept, but shell  2   b  and drum  50  have been removed. Drum  50  forms, with the parts which drive it in one direction or another, the main mobile element of the mechanism according to the invention. Drum  50  includes on each of its flanks  52   a ,  52   b  studs  54   a ,  54   b  rotatably mounted in bearings  44   a ,  44   b  provided in the inner faces of shells  2   a ,  2   b . Drum  50  also includes at its periphery an opening  56  corresponding to a through passage in which dosing chamber  11  will be mounted, provided with an ejection orifice  11   a , a plunger  10  comprising a head  12 , and a rod  13  having a groove  13   a  at its end. The particular structure of head  12 , which contributes to the precision of the quantity of liquid ejected and to the non-contamination of the chamber by external polluting agents will be explained in more detail with reference to the second embodiment. 
   The drum also includes a slit  58  in which two lateral arms  22   a ,  22   b  of a staple  20  are engaged, said staple being snapped into groove  13   a  of rod  13 , by compressing a spring  14  mounted on rod  13  of plunger  10 , when said staple  20  is moved, from the bottom of slit  58  to the edge of drum  50 . The movement of staple  20  is achieved by a double lever  24 , articulated in its median part in shells  2   a ,  2   b , each lever including an arm  26   a  pressing on each lateral arm  22   a ,  22   b  of staple  20 . Each arm  26   a  of double lever  24  also includes a snug  28 , allowing a safety catch  62  to be manoeuvred. 
   In proximity to slit  58 , drum  50  also includes a notch  64  in which safety catch  62  will be engaged, the function of said catch being described hereinafter within the scope of the description of the working of the apparatus. Finally, drum  50  includes on each of its flanks  52   a ,  52   b , two bean-shaped holes  66   a ,  66   b , the function of which is explained hereinafter. 
   On each of studs  54   a ,  54   b  of drum  50  there is mounted a pinion  60 , each pinion including along its axis two pins  61   a ,  61   b , more clearly visible in enlarged  FIG. 3A . When a pinion  60  is mounted on a stud  54   a ,  54   b  of the drum, pins  61   a ,  61   b  are engaged in holes  66   a ,  66   b , such that, when pinion  60  is driven in rotation, it has a small angle of shake during which drum  50  is not driven in rotation. 
   In  FIG. 4 , it can be seen that pinions  60  mesh with the toothings, on the one hand, of actuator  30 , and of a return member  40  on the other hand. 
   As indicated at the beginning, the actuator includes symmetrical branches  34   a ,  34   b , the spacing of which substantially corresponds to the width of the drum. Each branch  34   a ,  34   b  is formed of an external part ending in a stop member  36 , for manoeuvring arms  26   b  of lever  24 , and of an internal part formed by a straight rack  38  extending on either side of stop member  36  in the longitudinal direction of branches  34   a ,  34   b.    
   Return member  40  is formed by a double pivoting rack including two branches  40   a ,  40   b  connected by a bridge  42 , the pivoting rack being articulated in shells  2   a ,  2   b  of housing  2 . A return spring  46  allows the double rack to be kept in the low position when there is no pressure exerted on actuator  30  and to return it to this position when the actuator is released after having exerted pressure on the latter. 
   Finally, it can be seen that the inner surfaces of shells  2   a ,  2   b  each include a cam  6  having the shape of an arcuate rib. The end  22   a ,  22   b  of the lateral arms of staple  20  are capable of sliding on the external contour of rib  6  in order to keep spring  14  compressed during the rotation of drum  50  between the filling position and the ejection position. In the example illustrated cam  6  extends over an angle of approximately 120°. 
   The parts which have just been described, essentially with reference to the exploded view of  FIG. 3 , appear at least partially in the cross-section of  FIG. 2  where the mechanism is shown with its external cover  1  and a sliding member  8  for adjusting the distance between the ejection orifice and an eyepiece  8   a  located at its end. Sliding member  8  and eyepiece  8   a  are shown in two end positions in  FIG. 4 .  FIG. 3  also shows the cross-section line V—V corresponding to  FIGS. 5 to 9  which will now enable the operation of the mechanism to be explained. 
   The operation of this first embodiment is now described with reference to  FIGS. 5 to 9 . 
   Rest Position (FIGS.  5  and  5 A) 
   No pressure is exerted on actuator  30 . Safety catch  62  is engaged in notch  64  of drum  50  and the orifice of dosing chamber  11  is opposite the nozzle of receptacle  4 . Spring  46  rests on return rack  40 , keeping pins  61   a ,  61   b  in the low position in holes  66   a ,  66   b . The two ends of lever  24  are abutting respectively against stop member  36  and staple  20 . As the plunger head is pressed against the bottom of the dosing chamber, receptacle  4  is perfectly insulated from the external environment, and leaves no ullage. 
   Dosing Chamber Filling Position (FIGS.  6  and  6 A) 
   By exerting a pressure F on actuator  30 , stop member  36  tips lever  24 , and rack  38  drives pinion  60  to a high position in which pins  61   a ,  61   b  do not drive drum  50 . In this step lever  24  pulls plunger  10  thus sucking up the liquid from bottle  4  to fill the dosing chamber to a position where staple  20  is placed behind cam  6 . At this moment snug  28  of lever  24  pushes back safety catch  62  releasing drum  50 . In this phase, spring  46  starts to be compressed. 
   Passage into the Ejection Position (FIGS.  7  and  7 A) 
   By continuing to exert pressure F on actuator  30 , rack  38  drives pinion  60  which itself rotates drum  50 , by means of pins  61   a ,  61   b  which rest on one end of holes  66   a ,  66   b . During this rotation, staple  20  follows via its lateral arms the external contour of the rib forming cam  6 .  FIG. 7  shows the position just preceding ejection, orifice  11   a  of dosing chamber  11  being substantially on the axis of ejection. Rack  40  then exerts maximum compression on spring  46 . 
   The Ejection Position (FIGS.  8  and  8 A) 
   By exerting an additional pressure, the lateral arms of staple  20  go beyond the end of cam  6  so that the staple is no longer held. Return spring  14  of plunger  10  then pushes the plunger head to the end of dosing chamber  11  to eject the liquid. In this phase it will be observed that the pressure with which the liquid is ejected depends solely upon the characteristics chosen for spring  14 , and in no way upon those of return spring  46 , nor the manner in which the user exerts force F. 
   It will also be observed that, if the user does not reach this ejection position by releasing pressure F during filling or rotation of the drum, the dosing chamber is returned to its initial position and the unused product is re-injected into the receptacle. This constitutes a certain advantage when the product is a medicinal one whose price is generally high. 
   Return to the Rest Position (FIGS.  9  and  9 A) 
   By releasing the pressure after ejecting the liquid, return spring  46  tips rack  40  in the opposite direction driving drum  50  via pinion  60  whose pins  61 ,  61   b  are stopped at the other end of holes  66   a ,  66   b . At the end of rotation, drum  50  again occupies the position shown in  FIG. 5 . The apparatus is again in position for a new use. 
   With reference now to  FIGS. 10 to 18 , a second embodiment will be described hereinafter, in which the mobile element is formed by a valve  51 , able to be moved by the action of the actuator, along the same direction as the latter, to place, in a first phase, the receptacle containing the liquid in communication with the dosing chamber, then, in the second phase, in communication with the exterior. 
   The side view of  FIG. 10  shows a dispensing apparatus with the same external appearance as the previously described apparatus, and wherein the entire mechanism is masked by external cover  1 , leaving only actuator  30  visible, itself including an external cover  30   a , bottle  4  forming the receptacle containing a liquid, for example an ophthalmic solution, and slide  8  with its eyepiece  8   a.    
   The actual mechanism will now be described, referring essentially to  FIGS. 11 and 12 . It can be seen that the mechanism is assembled by means of frame  3  for receiving a unit  9  in which the dosing chamber is formed, more clearly visible in  FIG. 13A . Actuator  30  includes, perpendicular to its head  32 , a plate  31  provided with an aperture  31   a , and perpendicular to said plate a thick rib  33  including a snap-fitting groove  33   a  for a tipping element  41 , having a reverse L shape, an enlarged perspective of which is shown in  FIG. 12A . L-shaped element  41  forms the control member which acts, in a first movement phase of actuator  30 , on means for actuating plunger  10  against the action of a return spring  14 , and in a second phase on a valve  51  able to move in the same direction as actuator  30 , against the action of return springs  53   a ,  53   b  disposed between said valve  51  and frame  3 . As can be seen more clearly in enlarged  FIG. 12A , L-shaped tipping element  41  includes a recess  41   a , for receiving one end of a helical spring  47  and the other end of which is held abutting against thick rib  33  by means of a spacer  47   a.    
   Spring  47  is intended to hold element  41  abutting against a face of plate  31  during the active phase of actuator  30 , then to be compressed during the return to the rest phase to allow said element  41  to tip and move aside behind the control member of plunger  10 . The junction between the small branch  43  and large branch  45  includes on each of its edges pivots  45   a  allowing rib  33  to snap fit into groove  33   a . Large branch  45  includes, in its substantially median part, an aperture  45   b  opposite aperture  31   a  of plate  31 . At its base, branch  45  includes a corner shape  35  defining on the exterior an inclined plane  35   a  and in the interior two inclined ramps  35   b  parallel to inclined plane  35   a  and the width of which is substantially the same as the length of pivots  45   a.    
   Valve  51 , which can move in sliding channels  19  of unit  9  is described in more detail with reference to enlarged  FIGS. 12C and 13A . It is formed of a parallelepiped body including two edges  51   a  in which two grooves  51   b  are formed, allowing sliding on slide ways  19  of unit  9 . Its base includes an edge which includes small circular recesses  55   a ,  55   b  directed downwards to position return springs  53   a ,  53   b.    
   The surface delimited by the two edges  51   a  and pressed against the surface opposite unit  9 , includes at its centre an aperture  57  and a channel  59  whose ends  59   a ,  59   b  are located on either side of aperture  57  in the plane of symmetry of valve  51 . Aperture  57  is surrounded by an inner O ring joint  69   a  and channel  59  by an outer O ring joint  69   b , these joints  69   a ,  69   b  assuring sealing during movement of the valve. The longitudinal cross-section of  FIG. 13A  shows the filling position in which nozzle  4   a  of receptacle  4  is placed in communication with orifice  11   a  of dosing chamber  11 , by ends  59   a ,  59   b  of channel  59 , which preferably has the shape of the arc of a circle.  FIG. 14A  shows the ejection position in which aperture  57  of the valve is brought opposite orifice  11   a  of dosing chamber  11 , nozzle  4   a  then be blocked by the surface of valve  51 . 
   The actuating means for plunger  10 , shown in cross-section in  FIG. 12B  is formed by a clamp  21  including two large arms  23   a ,  23   b  ending in two lugs  29   a ,  29   b  the spacing of which substantially corresponds to the width of unit  9 . The large arms  23   a ,  23   b  are connected by a base  27  including a hole  27   a  for securing rod  13  of plunger  10  and a recess  27   b  for positioning return spring  14 . Lugs  29   a ,  29   b  each include two chamfers  25   a ,  25   b  having substantially the same inclination as inclined planes  35   a ,  35   b  of L-shaped tipping element  41 . As will be explained hereinafter for the operation of the device, chamfers  25   a ,  25   b  each co-operate with inclined planes  35   a ,  35   b , in a first phase, to act on plunger  10  filling dosing chamber  11  and, in the second phase, to allow the device to return to the rest position. 
   The cross-section of  FIG. 12B  also shows a new design of plunger head  12  providing both greater precision in the suction/ejection of a determined quantity of liquid, and safety as regards contaminating elements able to come from the exterior through the sliding cylinder of the plunger. Plunger head  12  is formed of two parts  16 ,  17  assembled by an assembling member  18  having the form of a rod provided with a head  18   a  and a collar. The first part  16  has the shape of an inverted double cone  16   a ,  16   b  through which assembling member  18  passes, to secure it in rod  13 , on the side of cone  16   a . This first part  16  is made of a hard plastic material, such as polypropylene (OP) or polyethylene (PE). The second part  17  is formed by a sealing gasket  17 , made of a flexible plastic material, such as a thermoplastic elastomer (TPE) or silicon, disposed in the second inverted cone  16   b  to fit into head  18   a  of pin  18 . The external part of gasket  17  has a hemispheric shape substantially corresponding to the shape of the bottom wall of the dosing chamber, as can be seen in  FIGS. 13A and 14A . This design allows no ullage to be left during ejection of the liquid, and thus a precise quantity of liquid to be ejected, which is particularly important for medicinal products, and particularly ophthalmic solutions. The lips (not referenced) of inverted double cones  16   a ,  16   b  enable external polluting agents to be confined at the depression of their junction. 
   Plunger  10  which has just been described, for this second embodiment is also that found in the first embodiment described hereinbefore. It is clear that this plunger constitutes a preferred embodiment allowing the objectives of precision and sterility to be achieved for the dispensing apparatus according to the invention, but other types of plunger can be used without departing from the scope of the mechanisms which have just been described, and the operation of which is explained in more detail with reference to  FIGS. 13 to 18 . 
   Filling Position (FIGS.  13  and  13 A) 
   From the rest position shown in  FIG. 11 , exerting a pressure F on the head of actuator  30 , the inclined plane  35   a  of L-shaped tipping element  41  slides the corresponding chamfer  25   a  of clamp  21 , pushing back plunger  10  and compressing spring  14 . In this position the base  4   a  of the receptacle is in communication with the orifice of dosing chamber  11  via channel  59  and enables dosing chamber  11  to be filled. 
   Passage into the Ejection Position (FIGS.  14  and  14 A) 
   By continuing to exert pressure F, the ends  43   a  of small arm  43  of the L-shaped tipping element press on valve  51 , compressing return springs  53   a ,  53   b  to move said valve  51  to a position in which its aperture  57  is opposite orifice  11   a  of dosing chamber  11 . In this phase, the plunger spring remains compressed. 
   Ejection Position (FIG.  15 ) 
   By continuing to press on the actuator, L-shaped element  41  releases clamp  21 , and allows the liquid to be ejected via the action of return spring  14 . 
   As indicated in the first embodiment, if the action on the actuator is interrupted, the quantity of liquid present in the chamber is re-injected into the receptacle. 
   Return to the Rest Position (FIGS.  16 ,  17  and  18 ) 
   By releasing the pressure on the actuator, in a first phase ( FIG. 16 ) the second inclined plane  35   b  of L-shaped element  41  is positioned behind the corresponding inclined plane  25   b  of clamp  21 . In a second phase ( FIG. 17 ), L-shaped element  41  tips compressing spring  47 , and in a second phase ( FIG. 18 ), L-shaped element  41  is returned to its initial position by spring  47 . This return to the rest position is actuated by springs  49  compressed via the action of the actuator. 
     FIGS. 19 ,  19 A and  20  show a variant of a second embodiment wherein a modified element is also applicable to the first embodiment. 
   In  FIG. 19 , which shows the apparatus in the rest position, it can be seen that actuator  30  is extended in the direction in which pressure F is exerted by a panel  39  insulating through passage  7  from the external environment when the apparatus is not being used. Panel  39  is provided with an aperture  37  which is placed opposite through passage  7  when the ejection position is reached, as shown in  FIG. 20 . This variant allows conditions of sterility to be increased, even if in the first embodiment the flank of the drum already forms, in the rest position, a first means for insulating the whole of the apparatus from the external environment. 
     FIG. 19  also shows variants relative to the second embodiment whose object is to make the apparatus according to the invention more economical. 
   The two actuator return springs  49   a ,  49   b  are replaced by a single spring  49  disposed between the inner face of actuator  30  and unit  9  of frame  3 . 
   It can also be seen that the body of actuator  30 , its external cover  30   a  and panel  39  are made in a single piece. The same is true of plunger  10  as regards clamp  21  and rod  13 . 
   Again with reference to  FIG. 19A , it can also be seen that L-shaped tipping element  41  has been modified and simplified, while fulfilling the same function, with, however, slightly different kinematics. Small branch  43  has been thinned so as to have sufficient flexibility to allow the L-shaped element to more aside upon return to the rest position; spring  47  has thus been omitted. It can also be seen that L-shaped tipping element  41  no longer includes pivots  45   a ,  45   b . Said tipping element  41  is driven in translation by actuator  30  by having the end of its small arm  43  gripped in an extension  48  of the actuator, whereas the large arm  45 , which still has a corner shaped end  35  with the two inclined planes  35   a ,  35   b , slides over a vertical wall  15  of unit  9  when a pressure F is exerted on actuator  30 . 
   It is clear that the devices described are arranged for multi-dose applications, i.e. applications in which doses are repeatedly drawn from a supply and repeatedly ejected. It is also clear that the devices are exemplified with features suitable for eye treatment applications. Typical parameters for this application will be given below although the invention shall not be regarded as limited to this application or any such exemplified parameter. A typical single dose volume for delivery to the eye can be less than 100 microliter, preferably less than 50 microliter, preferably less than 25 microliter, preferably less than 15 and most preferably less than 10 microliter. Generally the volume is at least 1, preferably at least 2 and most preferably at least 3 microliter. The liquid receptacle or supply line preferably has the capacity to deliver a plurality of such doses. A suitable speed for the stream of drops or jet ejected should be a balance between on one hand enough linear momentum to traverse an air gap between opening and target, without gravity assistance, and to travel fast enough not be obstructed by blinking and on the other hand not so fast as to cause inconvenient sensible impact on the eye. The ideal speed is to some extent dependent on the drop size used but as a general rule the drops should be able to traverse at least 1 cm, preferably at least 3 and most preferably at least 5 cm through air by own momentum, incorporating reasonable distances between opening and target. A suitable lower speed limit when leaving the opening is 1, m/s, preferably at least 5 m/s and most preferably at least 10 m/s. Generally the speed is lower than 200 m/s and preferably lower than 100 m/s. A suitable drop size so defined should be sufficient not to be retarded too quickly and not to be easily redirected, e.g. to be inhaled, and preferably has a minimum diameter of 20 micron, preferably not less than 50 micron and most preferably at least 100 microns. Normally the size is less than 2000 micron and preferably less than 1500 micron. The stream may take the form of a shower or spray of atomized liquid droplets but preferably the stream is narrow and fairly coherent although even such a stream tend to break up into individual droplets after a certain time of distance. The above given values are intended to relate to spherical droplets and for multiple droplets to the weight average of particle diameters. A coherent stream tends to break up into droplets of a diameter of roughly double the diameter of the stream. Accordingly suitable opening diameters for the containers are about half the above given drop diameters or roughly between 10 and 1000 microns, preferably between 20 and 800 microns. The above considerations are fairly independent of liquid viscosity and tend to apply both for solutions and ointments. It is desirable that the whole dose can be delivered in a time shorter than the blink reflex time, i.e. in a time shorter than about 150 ms, preferably shorter than 100 ms and most preferably shorter than 75 ms.