Abstract:
The dispenser orifice ( 13 ) may be closed off microbiologically tight by a valve plug ( 25 ) closing contrary to the direction of flow ( 11 ) and is opened against a spring ( 34 ) in the direction of flow ( 11 ). The medium gains access to the orifice ( 13 ) via throttling elements ( 22, 21, 49 ) so that it creeps practically non-pressurized to the attaching surface area ( 51 ) of a droplet former ( 50 ) where it accumulates into a droplet suspending in the upside-down position, as a result of which the medium contained in the dispenser ( 1 ) may be protected from germ contamination and the droplet may be simply administered to an eye or the like. Instead of being formed by a plunger pump ( 9 ) the delivery and compression chamber ( 15 ) may also be formed by a tube.

Description:
TECHNICAL FIELD AND BACKGROUND OF THE INVENTION 
     The invention relates to a dispenser with which flowable media may be released or discharged by pressurizing. Particulary liquid media, but also pasty, powdery and/or gaseous media are suitable. The dispenser is held and actuated single-handedly. The dispenser is primarily made by injection molding or of plastics. The medium may be discharged atomized, or delivered in discrete clusters or droplets having a volume of at least 5 or 15 μl and at the most 40 or 25 μl. The medium contains medicinal active substances for eye treatment, or the like. 
     Dispensers need to be microbiologically sealed to prevent the medium stored therein from being contaminated by germs gaining access from without. The medium needs to be protected from such detrimental effects during a long shelf life not only prior to first-time use (priming) of the dispenser but also after the initial or any following medium discharge. The dispenser may be for a single discharge of a medium dose in which its actuator is moved in one direction only up to the dispenser being totally emptied with no return or suction stroke being necessary. The total supply of the medium may be contained in a single delivery chamber, without any additional medium reservoir. The volume in the chamber is then variable for pressurized delivery of the medium. The dispenser or its actuator may also operate in two opposite direction via a working stroke for pressurized delivery directly followed by a return stroke for sucking a further medium dose into the delivery chamber. After discharge of a medium dose the microbiological seal is always able to be reproduced until the next discharge, which is not always necessary in the case of a disposable dispenser. 
     For this seal either a single valve or several valves may be suitable. The valves closing gaps are located in sequence in the flow direction in the outlet duct. The last or downstream valve is located as near as possible to the medium outlet or its opening bounds as formed by the transition between an inner circumference and an end face transversely adjoining this circumference. At this transition the medium detaches from all inner circumferences or internal dispenser faces for release to the environment. The medium may then still be guided downstream of the transition by accessible external dispenses faces. 
     OBJECTS OF THE INVENTION 
     An object is to provide a dispenser which avoids the drawbacks of known configurations and achieves advantageous effects of the aforementioned kind. Another object is to ensure a repeated microbiological seal against ingress of germs trough the bounds of the medium outlet or of inflow openings. A still further object is to provide for simple handling or for uncomplicated construction. An object is also to provide the dispenser for modular composition permitting adaptation to media differing in flowability. 
     SUMMARY OF THE INVENTION 
     The dispenser has a valve closing with high areal pressure. The valves closing gap may also form the cited bounds of the medium outlet. Thus the closing gap extends up to the outA ermost possible location of the outlet duct where the medium emerges on discharge as described. This location is a microbiological seal when the valve is closed. Thus, at the most, germs are able to collect on the permanently freely accessible outside of the dispenser but not gain access upstream past the tight closing gap to internal faces of the dispenser. 
     The closing force is not reduced until the medium pressure in the outlet duet has attained at least 0.7 or 1 or 1.4 bar. The valve could be opened by purely mechanical actuation independently of the medium pressure. The cited sealing effect and preventing germ ingress with the valve open may also be improved by keeping valve travel as small as possible. The maximum relative travel of the two valve elements for opening or closing is less than 2 mm, 1 mm, 0.7 mm or 0.4 mm, e.g. 0.3 mm. On droplet discharge the medium then emerges practically with zero pressure or in a capillary creeping action through the valve gap. Upstream thereof it is the cited higher pressure of the medium that maintains the valve open. Thus the emerging and the opening medium fractions communicate within the outlet duct. Further upstream, means such as a pump for generating a medium pressure higher than the aforementioned pressures, i.e. two to five times higher may be provided, the medium pressure amounting to e.g. at least 4, 6 or 7 bar. 
     With this pressure the valve may be kept open. When a pressure substantially lower as compared thereto is generated in the conveying chamber, for instance maximally or less than two or one bar, then for opening the final valve it is of advantage to provide means for transforming the force by a transmission ratio between the conveying chamber and the control member which opens the final valve. Therefor the opening pressure acts on correspondingly large faces areas of the control member. Compared thereto the faces on which the medium pressure acts in the closing direction are substantially smaller. 
     To nevertheless attain a discharge of the medium at the medium outlet at a pressure which as compared to the above is reduced or pressureless, a throttling gap is provided down-stream of the medium fractions which open the valve. The passage cross-section of the throttling gap is substantially smaller than that of the opened valve and may be varied as a function of the medium pressure. For example, the opened passage cross-section of the valve may be at least 2, 40 or 50 times more than the throttling cross-section. 
     Upstream of the final valve a further valve may be provided, featuring the throttles properties. This valve too, closes microbiologically sealed, directly upstream of the medium outlet by radial pressure. The closing faces of the throttling valve are located in the region of the nozzle duct forming the medium outlet or therein. One of these closing faces may be integral with one of the closing faces of the closing gap at the medium outlet. Thus the same valve body may form a movable or openable closing face of the valve and a stationary closing face for opening the other valve, for example with the final valve open. 
     At least one further throttle or valve is located upstream of the above valves in the outlet duct. For example the medium fraction serving to open the valve is already pre-throttled in permanently constant throttling cross-sections while flowing on toward the throttle or the final valve. The medium is also throttled at the output or transition from the conveying chamber into the outlet duct or shut off microbiologically sealed at this transition. For this purpose a spring-loaded outlet or pressure relief valve is suitable. For forming the closing gap the closing faces of each of the valves may have only linear contact or maximum closing pressure along a sole annular line, thus resulting in maximum specific areal pressures. One of the closing faces is thus bounded in each case as a sharp edge by two angularly interconnecting flanks or by a spherical face. 
     The medium is manually conveyed by a thrust piston pump or a flexible squeeze container, such as a tube. In the second case the complete valve control of the dispenser is arranged in the constricted tube tip which is in one part with the tube shell. In case of a piston pump the pump cylinder or pump piston thereof is included in the pump stroke motion commonly with the medium outlet. This motion is directed counter the opening direction of the movable valve body. 
     A droplet former is provided with which the medium, particularly in the upside-down position of the dispenser with the medium outlet oriented downwards, accumulates into an exposed droplet of a metered volume. The droplet then hangs at a diameter suspended on the dispenser, which diameter is smaller than the largest drop diameter. Thus the drop does not detach until its lower end face comes into contact with a counter face, such as the eyeball. The droplet thus not commences to flow onto the counter face until this contact is made. The droplet accumulator or droplet former has a convex and/or concave attaching face for the droplet. This face may be spherical or smooth or polygonal to increase the areal size at a same base areal extension. This face directly adjoins the closing faces of the final valve and is formed by the end of a needle traversing the medium outlet. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Example embodiments of the invention are explained in more detail in the following and illustrated in the drawings in which: 
     FIG. 1 is a side view of the dispender partially in cross-section and in the rest position, 
     FIG. 2 is a view of a further dispenser illustrated in actual size, 
     FIG. 3 is a partial axial section of an enlarged detail of FIG. 2, and 
     FIG. 4 illustrates still another dispenser with the valve open on commencement of the pump stroke and in the upside-down position. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 illustrates the dispenser  1  comprising two units  2 ,  3  with integral base bodies  4 ,  5 , the mutual displacement of which results in shortening and elongating the dispenser  1 . Supporting body  5  is sealingly secured by a flange  7  to the bottleneck of a reservoir  6 , for example a bottle of glass or the like. Units  2 ,  4  and  3 ,  5  form a pump  9  with a manual actuator  8 . All parts are located in axis  10 . On discharge, the medium flows parallel to axis  10  in direction  11  from unit  3  through unit  2  out of medium outlet  13  thereof. Unit  2  is thereby displaced commonly with outlet  13  in the opposite direction  12  and relative to unit  3 . 
     Outlet  13  may be oriented at right angles or transverse to axis  10  and is formed by the end of an outlet duct  14  traversing unit  2  only. The upstream end of duct  14  is directly connected to a conveying chamber  15  which is volumentrically variably bounded by two bodies  4 ,  5 . Upstream chamber  15  adjoins valveless a pre- or priming chamber  16  supplied valveless with medium via a riser duct  17  from the bottom of reservoir  6 . Corresponding to its emptying reservoir  6  receives a flow of atmospheric air from without on each working stroke via a venting means  18  which are bounded by bodies  4 ,  5 . The return stroke of units  2 ,  3  into the dispensers longer initial or rest position is powered by a spring  19  or a permanently pretensioned helical compression spring directly supporting on bodies  4 ,  5 . 
     In flowing from chamber  15  up to and out of outlet  13  the medium is controlled by a sequence of separate valves  20  to  23  located in this numerical and actual sequence from the vicinity of outlet  13  upstream up to the end of chamber  15 . Each valve forms a separate length section of duct  14 . Vent  18  is controlled via valve  24 . Valve  20  has two separate and internested valve bodies  25 ,  26  each in one part. The closing faces  27 ,  28  of bodies  25 ,  26  bound outlet  13 . At outlet  13  the medium detaches from the dispenser  1  into the environment or it remains attached to only one one-part and freely accessible outer face of the dispenser  1 . The outer, annular closing face or valve seat  28  is conically widened in direction  11  and forms the end of an integrally bounded nozzle bore or duct  29  of unit  2 . The inner complementary annular or conical closing face  27  is formed by pin-shaped body  25  which is moved in direction  11  by control means  30  for opening the valve when a correspondingly high medium pressure has been attained in chamber  15 , when valve  23  has opened and when the pressure has reached the downstream adjoining portion of duct  14 . 
     Control  30  includes a piston  31  with a piston lip conically widened in direction  12  and freely protruding from a piston crown. Fixedly anchored in the crown is the upstream end of body  25 . Duct  14  and the rotationally symmetrical stem  33  of body  25  traverse the crown where they commonly bound duct  14 . At the downstream end of body  25  the stem  33  has a widened head  32  which forms face  27  directly connecting to the outer circumference of stem  33 . Body  25  is loaded in the closed position by a permanently pretensioned spring  34  directly adjoining downstream the crown and surrounding only stem  33  as a helical compression spring within duct  14 . In the rest position body  25  is locked by an annular disk-shaped stop  35  which is in contact with the end of piston lip  31  and bounds duct  14  by its inner circumference. 
     Cap-shaped valve body  26  has a shell  36  which as compared to its outer diameter is up to twice as long. Shell  36  is integrally translated into end wall  37 . Wall  37  is traversed by duct  29  and outlet  13 . The end of shell  36  is step-wise widened in direction  12 . In this end a sleeve-shaped lug  38  of body  4  engages in direction  11 . Between the lugs end face and an annular inner shoulder stop  35  is fixed. Shell  36  extends up to a handle  39  of actuator  8 . 
     Body  26  of unit  2  forms in axis  10  or parallel thereto a nozzle-type discharge head  40  continually tapered in direction  11  up to its end and also suitable for being introduced into a bodily opening such as a nostril. The inner circumference of shell  36  forms up to stop  35  a sealing contact face  41  for piston  31 . The pistons inner circumference bounds  14 . Downstream thereof the same inner circumference forms a more constricted running face  42  for a likewise annular piston  43 . This pistons lip freely protrudes in direction  11  from the crown of piston  31 . Piston  43  also bounds duct  14  by its inner circumference. Provided between the duct sections bounded by pistons  31 ,  43  is the throttle  22 . The piston area of  31  which is effective in direction  11  is substantially larger than that of plunger  43  and acting in the opposite direction. Between the one-part lips of pistons  31 ,  43  their outer circumference adjoins an annular dry space which is permanently without contact with the medium. 
     Provided an annular piston or throttling body  44  downstream directly adjoins unit  31 ,  43  and is located in sleeve  36  and about stem  33 . Body  44  has a lip  45  freely protruding from the inner circumference of a crown in direction  11 . This lip sealingly contacts the outer circumference of stem  33  with radial pressure. A further lip  46  protrudes from the same crown and the outer circumference thereof in direction  11  about lip  45  and to the same extent. Lip  46  contacts with radial pressure the inner circumference of shell  36  and the inner face  47  of wall  26 . A sleeve-shaped stop  48  for piston  43  protrudes in the direction  12  from the same plunger crown. Spring  34  directly adjoins the two crowns of pistons  31 ,  33 ,  44  and is surrounded by sleeves  43 ,  48 . Lip  45  is radially spacedly surrounded, by lip  46 , while being not in contact with stop  47  due to widening of duct  29 . Lip  45  is acutely conically constricted in direction  11 . Its radial results in a motion vector for medium in direction  11 . Between stem  33  and lip  45 , on the one hand, and the inner circumference of duct  29 , on the other, an annular gap  49  of duct  14  is bounded in each case. This gap is sealed off, on the one hand, at lip  45  and, on the other, at faces  27 ,  28 . Spring  34  permanently urges face  27  in direction  12  against seat  28  with no self-locking effect. With valve  20  closed nozzle duct  49  is also bounded by part of face  27  due to it being longer than seat  28 . 
     Provided permanently freely accessible on the outside of the dispenser  1  and communicating with outlet  13  is a protuberance or droplet former  50  formed by head  32  and, where necessary, the adjoining parts of the bulging end face  53  of wall  26 . The exposed end face  51  of head  32  is curved spherically or hemispherically, it directly adjoining by a ring edge  52  the widest portion of face  27 . When valve  20  is closed edge  52  directly adjoins the outside  53  of wall  37  or the ring edge of seat  28  flanked by the latter. This ring edge bounds outlet  13  and is acutely flanked in axial cross-section, whereas edge  52  is obtusely flanked. 
     Provided permanently communicating in the region of the crown of piston  31 ,  43  are throttling ducts  54  of the throttle  22  in the form of longitudinal grooves in the outer circumference of stem  33 . The full passage cross-section of ducts  54  is substantially smaller than that from chamber  15  up to piston  31 , from piston  43  up to piston  44  and adjoining downstream lip  45 . It is, however, greater than that which exists at lip  45 , when throttle valve  21  is open, and between faces  27 ,  28 , when valve  20  is open. 
     Outlet valve  23  of pump chamber  15  has an actutely angled conical valve seat  55  of body  4  and a ball  56  of plastics, metal or the like having a spherical counter face. Valve body  56  is loaded in direction  12  by a permanently pretensioned spring  57  against annular or linear contact with valve body  55 . The helical compression spring  57  is in direct contact with bodies  35 ,  56 , it being center-located in direction  12  on a freely protruding finger of sealing body  35 . The finger defines the opening travel of body  56  by a stopping action. From valve  23  up to body  35  the duct  14  is bounded constant in width by stop  38 , the inner circumference of which is provided with longitudinal or control grooves which are spaced from the valve seat in direction  11 . Over a first opening travel of body  56  only a very small passage cross-section is opened, whereas over the subsequent opening travel up to the stop on body  35  the largest circumference of body  56  is in the region of the ducts  58 , thus opening up a correspondingly larger passage cross-section which is also larger than that of throttle  22 . Upstream adjoining the closing seat of valve  23  is a valve inlet  59  which is more constricted as compared to the latter and to chamber  15 . This valve inlet is formed by an appendage of body  4  freely protruding in direction  12  into chamber  15 . 
     Bodies  4 ,  5  form a housing  60  extending from an end wall  61  in direction  12  up to the upstream end of body  5 . Freely protruding beyond wall  61  of the latter in direction  11  is only body  26  or head  40 , the outer faces of which are freely accessible. An end face of wall  61  forms handle  39 . Beyond the other end face the shells  62  to  64  of body  4  protrude only in direction  12 . These shells are commonly in one part. Appendage  38  protrudes only beyond the face  39 . Body  5  comprises likewise with a spacing between its ends an end wall  65  permanently located within body  4  and shells  66  to  68  freely protruding in direction  11  and commonly in one part. Outermost and longest shell  62  permanently surrounds all remaining walls  63  to  68  and may be set back radially relative to the outer circumference of wall  61  to adjoin this outer circumference. Shell  63  next in sequence or middle shell located radially spaced within shell  62  is directly opposes by its outer circumference the inner circumference of shell  67  at which it adjoins sealingly by an end lip in the rest position. 
     Shells  66 ,  67  are located permanently between shells  62 ,  63 . Innermost shell  64  located radially spaced within shell  63  is located within inner shell  68 , from which shell  67  has the same radial spacing as from shell  66 . The upstream free ends of shells  63 ,  64  each form an annular piston lip widened at an acute angle in direction  12 . The inner circumference of shell  64  bounds chamber  15  with a cylindrical cylinder  69 , the upstream end of which is conically widened at an acute angle in direction  12  to form a closing face of an inlet valve  70 . Within shell  68  a piston  71  of body  5  freely protrudes from wall  65  permanently into shell  64  and comprises at the downstream end an annular lip  72  forming a valve body of valve  70 . In the rest position face  69  and lip  72  bound an annular inlet gap which is tightly closed after a first smaller stroke travel by lip  72  coming into contact with the slanting end of face  69 . Adjoining this annular gap upstream is an annular priming chamber  16  bounded by protuberances  68 ,  71  and end lip  73  of shell  64  since this lip slides permanently sealed on the inner circumference of shell  68 . 
     Radially spaced away within lip  72  the piston  71  comprises a protuberance or finger  74  sealingly or communicatingly engaging inlet  59  at the end of the pump stroke to unseat valve body  56  from seat  55  mechanically only as far as necessary to cause the valve to communicate without attaining its maximum passage cross-section. The protuberance of inlet  59  then engages the annular groove between protuberances  72 ,  74  and lip  72  comes into contact with the bottom of the annular groove about the protuberance. Adjoining the upstream conically tapered end of piston  71  are connecting members, such as ribs  75  of body  5 . Ribs  75  extend from the conical intermediate section of piston  71  and from within chamber  16  upstream only over part of the thickness of wall  65  as well as of the length of a slimmer finger  76  of piston  71 . Thus annular wall  65  is traversed in the center by an annular passage subdivided by ribs  75  circumferentially. At the end of the pump stroke the lip  73  is able to stop against the bottom of chamber  16  or against wall  65  and to receive the sections of parts  75 ,  76  protruding therebeyond. 
     The conically widened end lip  77  of shell  63  is set back from piston lip  73  in direction  11  and slides after a first short partial stroke of the working stroke over a control face or step  78  of the inner circumference of shell  67 . Thus valve  24  is opened on closing of valve  70 . Shells  67 ,  68  bound in conjunction with shells  63 ,  64  an annular chamber  79 . It is into this chamber that air is able to flow or be drawn in from its inflow between shells  62 ,  66 ,  63 ,  67 . 
     Bottom  65  of chamber  79  is traversed by a communicating duet  81  which is totally covered by a filter  80  annular about axis  10  in chamber  79 . Disk-shaped filter  80  is radially urged in contact with shells  67 ,  68  as well as with bottom  65  and may be attained or dislodged by valve element  73  at the stroke end. Spring  19  surrounds parts  63 ,  64 ,  67 ,  68 ,  80  it being located in the annular chamber directly between shells  62 ,  63 ,  66 ,  67  and directly supported on walls  61 ,  65 . 
     Flange  7  forms an annular disk-shaped seal  82  engaging at the end face of wall  65  facing away from member  80  the annular gap thereof with zero radial clearance or the outer and inner circumference with radial pressure. Member  82  has at its downstream end side an annular groove bounding with wall  65  an annular duct traversing axis  10  and adjoining the communicating duct  81 . Adjoining the inner circumference of seal  82  is a cap  84  of the one part flange  7  protruding in direction  12 . Cap  84  is engaged by a sleeve-shaped appendage  83  of body  5  protruding from wall  65 . Adjoining the bottom of the annular groove in line with the communicating duct  81  is a further communicating duct traversing seal  82  and continued as an inclined groove in the outer circumference of shell of cap  84 . The free end of finger  76  protruding beyond ribs  75  in direction  12  is conically or pointed tapered, it engaging with radial spacing therefrom a conical hole in the bottom of cap  84  to thus define an annular inlet opening widened in the shape of a hollow cone in direction  11 , the communicating cross-sections of which are substantially smaller than those in the region of ribs  75  or of chambers  15 ,  16 . Protruding from the end wall of cap  84  solely in direction  12  is a mount, such as a sleeve  85  of flange  7  into which the riser tube is inserted . 
     Together with wall  65  and upstream thereof body  5  forms a cap or connector  86  for engaging the reservoir neck, the annular end surface area and the annular opening edge of which is set back from the latter adjoins with axial or radial pressure the seal  82  and outer circumference of cap  84  and are respectively firmly seated. The inner circumference of cap  86  is provided with a fastener or tensioning member, such as a thread, engaging a corresponding counter member on the outer circumference of the reservoir neck. The end of shell  86 ,  87  comes up against an annular shoulder of reservoir  6 , this shoulder being formed by the transition between the barrel and neck of reservoir  6 . At the end of the pump stroke body  4  does not come into contact with the annular shoulder of shell  87  by shell  62 . 
     Units  2 ,  3  and bodies  4 ,  5  are positionally locked by a captive anti-twist lock  90 . Provided in shell  62  is a slot  88  adjoining wall  61 . The end of this slot is offset in direction  11  relative to the free end of shell  62  and in which a cam  89  engages at the outer circumference of shell  66 . In the rest position the radially freely protruding cam  89  comes up against the end of the slot in the plane of the downstream end face of wall  65 . Body  4  is mounted on body  5  in direction  12 , the cam  89  springingly widening shell  62  by an inclined face until cam  89  snaps into place in slot  88 , namely after walls  62  to  69  have clasped each other to interengage. Bodies  35 ,  56 ,  57  are inserted in body  4  in direction  12 . Also body  40  is mounted in direction  12  on body  4 . Bodies  31 ,  34 ,  44  are previously inserted in body  40  in direction  11 . Either before or thereafter body  25  is inserted into bodies  4 ,  40  in direction  12  and the fixed connection made to piston  31 ,  43 . The free end of shell  63  is set back relative to the free ends of shells  62 ,  64 . The free end  73  of shell  64  is set back relative to that of shell  62 . The free ends of shells  66 ,  67  are set back relative to that of shell  68 . Shell  66  is set back relative to shell  67 . Relative to the free ends of shells  66  to  68  the piston  71  is set back. Body  56  is located in the plane of wall  61 . Bodies  25 ,  31 ,  41 ,  43 ,  44  are located totally outside of body  4  and in direction  11  are permanently spaced from body  4 . 
     For the pump and working stroke handle  39  is squeezed by two fingers on both sides of head  40  and unit  2  displaced relative to unit  3  in direction  12  against spring  19 . After a stroke of less than a millimeter inlet valve  70  closes, chambers  15 ,  16  thereby being totally filled with medium. Immediately thereafter valve  24  opens and any vacuum in reservoir  6  is compensated. In the further stroke the pressure increases in chamber  15  until the cracking pressure of valve  23  or body  56  is attained by cam  74  prior to the end of the working stroke, resulting in body  56  opening in direction  11  at seat  55  against the force of spring  57  either with the cited smaller passage cross-section or subsequently with the passage cross-section of duct  58 . The medium thus gains access by the pressure in chamber  15  to duct  14  through body  35  into the dished recess of piston  31 . Piston  31  is moved by this pressure against spring  34  together with body  25  in direction  11  until lip  43  comes up against lip  48 . At the same time the medium flows from the piston dish  31  damped by the throttle  22  with increased flow velocity into the, in turn significantly widened piston  43 ,  48  where calming and deceleration of the flow occurs. The opening stroke of parts  25 ,  31 ,  43  amounts to but 0.3 mm for a maximum diameter of the opening  13 ,  28  of 5 mm, 4 mm or 2 mm. 
     From the calming chamber the medium flows directly against the inner circumference of lip  45 . Lip  45  is unseated radially by the pressure of the medium from the cylindrical portion of stem  33  by a lift of maximally three or two tenths of a millimeter which is at least 10 or 20 times smaller than the axial stroke of the closing face  28 , e.g. between 0.005 and 0.01 mm. The cracking pressure of valve  20  is with 1.5 bar at least half of the pressure in chamber  15  which may be in the range 7 bar to 8 bar. At the output of valve  21  the medium again gains access to a widened calming space bounded between lips  45 ,  56  and the upstream end of duct  29  and stem  33 . From here the medium flows very slowly along stem  33  in duct  49  between the separate faces  27 ,  28 , it creeping over edge  52  onto the face  51  where it accumulates into a droplet of 20 μl attaching thereto. In the upside-down position of the dispenser  1  and in all valve positions this droplet is then freely suspended from face  51 . Piston  44  is permanently stationary relative to housing  36 ,  37 . The calming chamber between pistons  43 ,  44  is variable in volume, it varying with the lift of valve  20 . 
     Once the pressure drops in chamber  15  at the end of the stroke of pump  9 , spring  57  closes valve  23  which may first close the communicating ports of ducts  58  and bound the more restricted passage cross-section before then sealing at seat  55  to thus permit a subsequent flow of the medium from chamber  15  into duct  14 . At the same time as each of the cited closing actions of valve  23  and depending on the calibration the valve  20  closes before or thereafter, spring  34  thereby seating valve body  25  over the cited stroke in seat  28 . Likewise at the same time as each of the cited closing actions and depending on the calibration valve  21  also closes before or thereafter. Accordingly the space between the closing face  28  and lip  45  remains either totally filled with medium or it is emptied at least in part. From lip  45  to seat  55  the duct  14  always remains after first-time use (priming) totally filled with medium, however. When valve  20  is closed, first piston  43  unseats from stop  48  defining the cited stroke flexibly or rigidly. At the end of the return stroke spring  19  opens valve  70  to cause the medium suctioned into chamber  16  on the return stroke by piston  73  to abruptly flow into the evacuated chamber  15 . At the same time medium is subsequently suctioned through conduit  17  into chamber  16 . The medium thereby flows about parts  76 ,  75 ,  71 . In the rest position chambers  15 ,  16  are permanently in communication due to valve  70  being open. Shortly before the end of the return stroke, valve  24  of chamber  79  also closes, from which air has flowed through flange  7  into reservoir  6  whereby any germs in the air are killed in filter  80 . 
     Conduit  17  and appendage  85  may also be eliminated, the pump  9  then priming medium from reservoir  6  through flange  7  only in the upside-down position, since it is in this position that the medium flows by the force of gravity up to and into chambers  15 ,  16 . 
     Referring now to FIGS. 2 to  4  it will be appreciated that like parts have like reference numerals as shown in FIG. 1 but indexed differently, all passages of the description applying to all aspects and all features of all embodiments possibly being provided in addition and in combination, and thus all passages of the description applying accordingly to all embodiments. 
     Referring now to FIGS. 2 and 3 there is illustrated how the reservoir  6   a  and pump  9   a  of the dispenser la are formed by a flexible or resilient squeeze receptacle in the form of a tube elongated along the axis  10   a . The bodies  4   a ,  5   a  are configured integral with each other. Outer sides facing away from each other of tube shell  62   a ,  66   a  integral circumferentially and full-length form the handles  39   a  for squeezing and shortening the reservoir volume. The head  40   a  including the walls  36   a ,  37   a ,  38   a  are configured integrally with the shell  62   a ,  66   a  and translate into the intermediate section  61 a concically flared in the direction  12   a . The end of the reservoir  6   a  remote from the orifice  13   a  and head  40   a  is initially cylindrically open. The control  30   a  or the parts  31 a,  33   a ,  34   a ,  35   a ,  43   a ,  44   a  are accordingly introduced in the direction lla and brought into the function position in the body  26   a  either one after the other or as a preassembled unit. Then, the medium is filled through this opening into the reservoir  6   a , after which this end is is squashed flat until opposing wall sections  62   a ,  66   a  are directly in contact with each other over a transverse strip as an endless band and are secured to each other by a bonding procedure, such as welding, to thus form a closure  7   a  for the reservoir space and the compression chamber  15   a . The volume of the reservoir  6   a  is thus diminished with each metered discharge of medium as its medium volume. This may also be achieved by a climbing plunger which, instead of the closure  7   a  is included in the movement of the medium in the direction  11   a  slidingly sealed to the inner circumference of the reservoir  6   a.    
     The plunger  31   a  forms with the stem  33   a  a preassembled or integral unit and is not in contact with the body  35   a  in the starting position. This body forms merely a constricted throttling element  23   a  for the valveless transition of the medium from the compression chamber  15   a  to the passage  14   a  . The stem  33   a  totally surrounds the passage  54   a  emerging between the seals  43   a ,  49   a  via a transverse passage  22  directly into a flared, annular mollification chamber surrounding it. This chamber has always the same volume. The lip  43   a  slides on the outer circumference of the stem  33   a , this lip being formed together with the stop  48   a  by an annular or sleeve body separate from the bodies  31   a ,  33   a ,  44   a  and sealingly in contact over its full length also including the stop  48   a  with the surface area  42   a , like the body  44   a . The outer sleeve of the sealing body surrounds the lip  43   a  thereof with radial spacing, forms with one end the stop  48   a  and is in permanent contact by the other end with the outer sleeve of the body  44   a  on the face side. Like the lip  43   a  the lip  45   a  slides on the outer circumference of the stem  33   a  in its working movements. The lip  46   a  is conically tapered in the direction  11   a . The head  32   a  translates at the more constricted end of the surface area  27   a  incrementally into a slimmer, finger-like appendage inserted as a fastenening member into a blind hole of the stem  33   a  in the direction  12   a  and defined with zero axial clearance and preventing from twisting out of place by a snap action connector. The corresponding snap action members are configured integrally with the stem  33   a  and with the head  32   a . The parts  33   a ,  32   a  adjoin each other flush by face surface areas the same in size. The bottom of the blind hole is located spaced away from the passage  54   a . The spring  34   a  is directly supported by the body  43   a ,  48   a , urging it against the body  44   a  as well as the latter against the stop  47   a . The spring  34   a  is located in the dry space defined by the lips  31   a ,  43   a . As indicated dot-dashed the end surface area  51   a  may also be curved concave or dished to reliably hold the droplet on an as small a base surface area as possible. 
     With the fingers of one hand the user of the dispenser  1   a  is able to produce a pressure of maximally 0.4 to 0.6 bar in the chamber  15   a  as a rule by squeezing the handles  39   a  radially oriented to the axis  10   a . The effective surface area of the plunger  31  is selected correspondingly large to nevertheless overcome the counterforce of the spring  34   a  in opening the valve  20   a . The counteracting plunger surface areas of the bodies  43   a ,  48   a  and  44   a  are correspondingly smaller. To increase the pressure in the chamber  15   a  a translation of the actuating force may also be provided which engages the surface areas  39   a  and forming therefor e.g. a lateral acting lever or a clamp or pincer. This lever may form radially spaced away from the reservoir  6   a  the handles of the discharge actuator  8   a  and comprise on the other side of the axis  10 a a hinge, such as a flexing or spring hinge integrally joining the pincer levers for their mutal movement. The spring  34   a  is arranged in the dry space without coming into contact with the medium. The levers or other members may also join several dispensers  1   a  together through a set of design break points. The dispensers  1   a  located parallel juxtaposed may also be singled by parting the flush levers or straps. 
     Referring now to FIG. 4 there is illustrated the plunger unit  71   b  arranged on the unit  2   b  firmly seated seated with a plunger actuator. Secured to the actuator is an integral, flexible plunger sleeve, the downstream end of which forms the axially compressible spring  57   b  and the other end of which forms in the direction  12   b  the flared lip  72   b . In between the plunger sleeve forms the annular valve element  56   b , the seat of which  55   b  forms the actuator. The plunger sleeve is penetrated by the outlet passage and a core body comprising the passages  58   b  at the outer circumference. Secured to this body protruding in the direction  11   b  by a flared end  75   b  is a sleeve  76   b  locking the plunger sleeve in place. Secured to the sleeve  76   b  is a further sleeve  38   b , the downstream end of which engages firmly seated the upstream end of the shell  36   b  via a snap-action lock. Both shells  38   b ,  36   b  are penetrated by the outlet passage  14   b  and define with the plunger  31   b  the mollification chamber. The shell  67   b  protrudes freely into the reservoir  6   b  and defines the chamber  15   b , this shell comprising an inner shoulder  74   b  which stops the lip  72   b  at the end of the pumping stroke so that the valve  23   b  is opened in the subsequent travel of the stroke. Mounted on the end of the shell  67   b  in the direction  12   b  is an annular cover which may also be configured integral with the shell  67   b  or body  5   b . The shell  66   b  of the cover snugly clasps the outer side, and the shell  68   b  the inner side of the shell  67   b . The open end of the shell  67   b  is defined between the shells  65   b ,  66   b  by a snap-action lock. The flange  7   b  is configured integral with the cover. The end of the shell  68   b  forms the valve element  78   b  of the valve  24   b  and the conical outer side of the lip  72   b  the movable valve element thereof. The cover is penetrated by the plunger actuator, the plunger sleeve being permanently located therein over the majority of its length. The sleeve  38   b  may be configured integral with the sleeve  76   b  and form the stop  35   b.    
     The valve  70   b  is located in the upstream end  85   b  of a constricted end section  83   b  of the shell  67   b  and is configured as a pressure relief valve having a valve ball corresponding to the valve  23 . Its valve element is loaded by the spring  19   b  in the closed position, this spring being located in the chamber  15   b  and supported by the core body. The vent  18   b  is defined between the cover and the plunger sleeve. Downstream of the valve  23   b  the vent passes through the shell  67   b  outside of the chamber  15   b  so that air flows therefrom through the filter  80   c  into the reservoir  6   b . The filter forms at the same time the reservoir seal directly in sealing contact with the flange  7   b  and with the shell  67   b.    
     An inlet  16   b  from the reservoir  6   b  to the chamber  15   b  may also pass through the wall  67   b  directly adjacent to the seal  80   b . The definition of the inlet  16   b  forms with the lip  72   b  an inlet valve or slide valve which is closed after a first portion of the stroke travel and is reopened towards the end of the return stroke, thus enabling the reservoir  6   b  to be totally emptied. This valve as well as the valve  70   b  are configured without a riser conduit  17  so that priming the medium is only possible in the upside-down position. The shell  67   b  could also be sealingly closed at the upstream end instead of an inlet opening. 
     The wall  61   b  is conically flared at right angles in the direction  12   b  and directly slidingly adjoins the outer circumferences of the shells  36   b ,  62   b . The handle  39   b  comprises protuberances or coaxial annular cams to prevent the fingers slipping out of place. The shells  61   b ,  62   b  permanently surround the body  5   b  over the majority of its length so that only the end  83   b  protrudes. For securing the body  5   b  a crimp ring  86   b  is provided within the shell  62   b , this crimp ring contacting the flange  7   b  and a corresponding flange of the reservoir neck by the face side in each case and accommodating in the interior the seal  80   b.    
     Indicated evident in FIG. 4 is the suspended 20 μl droplet, the volume of which is maximally three or two times or just as large as the volume of the head  32   b . In FIG. 4 the valve  20   b  is shown open and the plunger  72   b  is in the starting position at the start of the pumping stroke. FIG. 4 also indicates dot-dashed a protective cap for the head  40   b , this protective cap being in close or sealing contact with the outer sides of the walls  36   b ,  37   b ,  61   b  and is to be removed from the dispenser  1   b  in the direction  11   b . At the face wall the cap comprises a protuberance which presses linearly pointwise or annularly against the surface area  51   b  of the body  25   b  in its closed position, whereas all other portions of the surface area  51   b  are without contact, as a result of which, however, the closing pressure between the closing surface areas of the valve  20   b  is enhanced during the shelf life of the dispenser. 
     The dispenser  1   a  may be composed of maximally six or only four injection molded plastics parts as well as the spring  34   a . For instance, the parts  43   a ,  44   a ,  48   a  or the parts  35   a ,  36   a ,  38   a  may be configured integral with each other. Without the reservoir  6  the dispenser  1  may consist of seven or eight such injection molded parts to which three springs  19 ,  34 ,  57 , the body  56 , the filter  80  and, where necessary, the riser tube  17  are added. The bodies  5 ,  7 ,  82 , the bodies  31 ,  44  and the bodies  4 ,  35  could be likewise configured integral. Each of the springs could also be configured integrally of a plastics material with one or both of the components by which they are directly supported. All cited features and properties may be provided precisely as described, or merely substantially or approximately so and may also greatly deviate therefrom depending e.g. on the viscosity of the medium. The size relationships as described are particularly favorable, more particularly when the length of the dispenser  1  as measured over the bodies  4 ,  5 ,  40  is smaller than 10 cm or 7 cm and its largest bore, smaller as compared thereto, is smaller than 5 cm or 3 cm.