Abstract:
A foam dispensing mechanism ( 100; 600 ) comprises: a top ( 113 ); a cylindrical wall ( 112; 612 ) extending from a peripheral edge of the top; a piston member ( 170 ) arranged within the cylindrical wall; a dispense head ( 120 ) axially displaceable with respect to the top; a resilient bias member ( 130 ) for biasing the dispense head. The piston member has a first opening ( 176 ) and a coupling cylinder ( 178 ) arranged coaxially around said first opening. The dispense head has a cylindrical seal member ( 150 ) positionally fixed with respect to the dispense head ( 120 ), the seal member ( 150 ) having a first passage opening ( 156 ) with a valve seat ( 151 ), wherein the seal member&#39;s lower portion ( 157 ) is sealingly and axially slidably coupled to the coupling cylinder. An axially displaceable valve member ( 190 ) for blocking or releasing said first passage opening has a valve stem ( 192 ) having its end ( 193 ) coupled to the piston member.

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application is the US National Phase Entry of International Patent Application No. PCT/NL2013/000043 filed Sep. 3, 2013, which claims priority to NL Patent Application No. 1039786 filed Sep. 3, 2012. 
     FIELD OF THE INVENTION 
     The present invention relates in general to a foam dispenser. 
     BACKGROUND OF THE INVENTION 
     As schematically illustrated in  FIG. 1 , a foam dispenser  1  generally comprises a container  2  having a mouth piece  3  at its top. The container  2  contains a substance  4 , which turns into a foam on release. An example is soap, or shaving foam. In normal use, the container  2  is standing upright, and foam is dispensed from the mouth piece  3  by a user pressing the mouth piece down. 
     For achieving the dispensing action, the dispenser  1  comprises a pump mechanism actuated by the mouth piece. The combination of mouth piece and pump mechanism is typically implemented as a unit that is provided with a screw connector or a snap connector, for being screwed or snapped on a cylindrical neck portion of the container. 
     In prior art, the pump mechanism comprises a buffer chamber, on the one hand coupled to the interior of the container, on the other hand coupled to the mouth piece. On the down stroke of the mouth piece, a first flow path between the interior of the container and the buffer chamber is closed, a second flow path between the buffer chamber and the mouth piece is opened, the pressure within the buffer chamber is increased, and substance is pressed from the buffer chamber towards the mouth piece. On the up stroke of the mouth piece, the first flow path is opened, the second flow path is closed, the pressure within the buffer chamber is lowered, and substance is sucked from the container into the buffer chamber. 
     SUMMARY OF THE INVENTION 
     The present invention aims to offer a different design, potentially capable of being manufactured easier and cheaper. Particularly, the present invention aims to provide a soap dispenser in which the pump mechanism does not have an integrated buffer chamber that in use is subjected to alternating overpressure and underpressure. 
     To attain this objective, an important aspect of the present invention is that the container itself is used as a pressure chamber. The pump mechanism comprises a piston arranged in the container. The interior of the container communicates with the mouth piece. On the down stroke of the mouth piece, a first flow path between the container and the mouth piece is opened, the piston is moved down to increase the pressure in the container, and substance is pressed from the container towards the mouth piece. On the up stroke of the mouth piece, the first flow path closed, the piston is moved up and air is allowed to flow into the container to equalize the pressure in the container and to stop the flow of substance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other aspects, features and advantages of the present invention will be further explained by the following description of one or more preferred embodiments with reference to the drawings, in which same reference numerals indicate same or similar parts, in which indications “below/above”, “higher/lower”, “left/right” etc only relate to the orientation displayed in the drawings, and in which: 
         FIG. 1  schematically shows an example of a dispenser; 
         FIGS. 2-7  show schematic longitudinal sections of an embodiment of a dispenser according to the present invention, in various stages during its operation; 
         FIGS. 8A-8C  schematically illustrate variations of the dispenser; 
         FIG. 9  shows an embodiment of a dispenser according to the present invention in the various stages during its operation; 
         FIGS. 10A-10E  show the same stages of the same dispenser at a larger scale; 
         FIG. 11  is a figure comparable to  FIG. 2 , showing a variation of the dispenser. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 2  schematically illustrates an embodiment of a foam dispenser  100  according to the present invention, in which the mouth piece is integrated with the container. 
     The dispenser  100  comprises a container  110 , with a bottom  111 , a substantially cylindrical wall  112 , and a top  113 . In order to allow assembly and filling, the bottom  111  is separate from the wall  112 , and is attached to the wall by a snap connection, or by screwing, or welding, or any other suitable manner, as should be clear to a person skilled in the art. The top  113  has a cylindrical upright portion  114  around an opening  115 . The cylindrical upright portion  114  may extend upwards from the top  113  itself, or from the bottom  116  of a recess  117 , as shown. 
     The dispenser  100  comprises a cap-shaped dispenser head  120 , having a substantially cylindrical wall  122  and a top wall  123 . A cylindrical partition wall  124  extends down from the top wall  123 . A dispense pipe  125  extends horizontally from an opening in the partition wall  124  through the wall  122 ; its free end  126  constitutes the outlet opening of the dispenser. The dispenser head  120  with this dispense pipe  125  thus constitutes the mouth piece mentioned above. 
     The dispenser head  120  is positioned with radial play in the recess  117 . It can move axially up and down with respect to the container  110 . In a possible embodiment, the dispenser head  120  is free to rotate about the vertical axis. In another possible embodiment, the dispenser head  120  has a first angular position in which the dispenser head  120  can move axially up and down with respect to the container  110 , and a second position in which the axial position of the dispenser head  120  with respect to the container is fixed in order to prevent inadvertent use of the dispenser, for instance during storage and transport. The following explanation applies with the dispenser being in a situation where the dispenser head  120  can move axially up and down. 
     The dispenser head  120  can move down until the lower end of its wall  122  abuts the bottom  116  of the recess  117 . The dispenser  100  is provided with a resilient member  130  pushing the dispenser head  120  axially upwards, away from the container  110 . In the embodiment shown, this resilient member  130  is implemented as a helix spring arranged around the cylindrical upright portion  114  and within the head wall  122 . 
     The dispenser  100  comprises a generally cup-shaped mixing chamber  140 , arranged within the dispenser head  120 . The mixing chamber  140  has a bottom  141  and a substantially cylindrical wall  142  with an open top. The bottom  141  has one or more openings  143 , serving as entrance opening to the interior space  144  of the mixing chamber  140 . The upper end of the wall  142  abuts the lower end of the partition wall  124 , or is held in close proximity thereof. The open top end of the mixing chamber  140 , or otherwise an opening in a top of the mixing chamber  140 , serves as output opening  149  from the interior space  144  of the mixing chamber  140 . It will be understood that this output opening thus communicates with the dispense pipe  125 . 
     In its interior space  144 , the mixing chamber  140  carries one or more mixing meshes  145 ,  146 . In the embodiment shown, the mixing chamber  140  carries two mixing meshes  145 ,  146 . Such meshes are preferably arranged in respective radial planes, as shown, at an axial distance from each other. In the embodiment shown, the lower mesh  145  is carried on an internal radial step  147  of the chamber wall  142 , and the upper mesh  146  is carried on the upper end of the wall  142 . Going from entrance opening  143  upwards to the top end of the mixing chamber  140 , a next mesh is finer than a previous mesh. 
     The mixing chamber  140  is held in place with respect to the dispenser head  120  by a substantially sleeve-shaped seal member  150  having a substantially cylindrical wall  152  encompassing the mixing chamber  140  and the partition wall  124 . At its top end, the seal member  150  engages the partition wall  124 , so as to be axially fixed with respect to the dispenser head  120 . Further, the seal member  150  has a radial flange  153  forming an upper abutment for the resilient member  130 ; it is noted that the bottom  116  of the recess  117  forms a lower abutment for this resilient member  130 . Corresponding with said internal radial step  147 , the chamber wall  142  has a radial shoulder  148 , and the seal member  150  has a corresponding internal radial step  154  contacting the radial shoulder  148 , so that the seal member  150  pushes the mixing chamber  140  axially upwards and holds the mixing chamber  140  fixed with respect to the dispenser head  120 . 
     The seal member  150  comprises an annular sealing portion  155  capable of cooperating with the inner wall surface of the cylindrical upright portion  114 . Advantageously, this annular sealing portion  155  is implemented as a slightly tapering skirt portion, as shown. 
     The seal member  150  comprises a bottom  151  with a central opening  156 . The above-mentioned skirt-shaped sealing portion  155  is preferably extending downwards from the transition between wall  152  and bottom  151 , as shown. The seal member  150  further comprises a cylindrical extension member  157 , extending downwards from the bottom  151  and arranged around said opening  156 . 
     The dispenser  100  further comprises a substantially disc-shaped piston member  170  arranged within the container  110 , having a circumferential edge  171  for sealing against the inner surface of the container wall  112 . The piston member  170  has a disc body  172 , that may extend substantially radially, as shown, and a central piston cup  173  with a cup wall  174  and a cup bottom  175  having a central opening  176 . The cup wall  174  has an upper portion  174   a  extending upwards from the disc body  172 , and a lower portion  174   b  extending downwards from the disc body  172 . The diameter of the upper portion  174   a  may differ from the diameter of the lower portion  174   b . At its lower side, the piston member  170  carries the upper end of a dip tube  109 , which extends to the bottom  111  of the container  110 . For instance, the dip tube may be clamped in a cylindrical mount  177  extending downwards from the cup bottom  175  and arranged around said central cup opening  176 . 
     The piston member  170  divides the interior of the container  110  in a substance compartment  210  below the piston and an air compartment  220  above the piston. In use, the substance compartment  210  will be at least partly filled with substance  4 . When the container  110  is standing upright, the substance  4  will be in the lower part of the substance compartment  210 , with air above the substance in the upper part of the substance compartment  210 . 
     The piston member  170  further comprises a cylindrical extension member  178 , extending upwards from the cup bottom  175  and sealingly connecting to the extension member  157  of the seal member  150  while being able to be axially displaced with respect to the extension member  157  of the seal member  150 . In the embodiment shown, the cylindrical extension member  178  has an outer surface sealingly sliding within the inner surface of the extension member  157  of the seal member  150 , but alternatively this is the other way around. 
     The dispenser  100  further comprises a valve member  190  with a substantially T-shaped longitudinal section, comprising a valve head  191  and a valve stem  192  extending downwards from the valve head  191 . At its lower end, the valve stem  192  is provided with an arrow-shaped stem head  193 , which has a diameter larger than the diameter of the stem immediately above the stem head  193  such as to have a step-shaped transition  194  between the stem  192  and the stem head  193 . The valve head  191  is resting on the bottom  151  of the seal member  150 , i.e. located between the bottom  141  of the mixing chamber  140  and the bottom  151  of the seal member  150 , with the valve stem  192  extending downwards through the opening  156  in the bottom  151  of the seal member  150 . The stem head  193  is engaging below fixation fins  179  extending radially inwards from the inner surface of the upwards extension member  178  of the piston member  170 . 
     Assembly is as follows. The valve member  190  is placed in the seal member  150 , and the mixing chamber  140  is placed in the seal member  150 , above the valve member  190 . Subsequently, the dispenser head  120  is fitted on the seal member  150 ; this advantageously is a snap fitting. Said part together now form a head unit  200 . With the container bottom  111  absent, the piston member  170  is placed in the container  110  and pushed upwards. The head unit  200  is placed on the top of the container  110 , with the spring member  130  in between. The head unit  200  is pushed down and the piston member  170  is pushed up, until the stem head  193  snaps behind the fixation fins  179  of the piston member  170 . To facilitate the engagement, the stem head  193  may advantageously have a tapered front face and the fixation fins  179  may advantageously have sloping top edges, as shown. 
     When the dispenser head  120  is now released, it is pushed up by the spring member  130 . It will easily be seen that the seal member  150  pushes the valve member  190  up, which in turn takes along the piston member  170 , until the piston member  170  abuts the bottom  116  of the top recess  117  (or any other stop). The assembly is now in its normal position, also indicated as rest position or transport position. 
     As a next step, substance is filled in the container (which to that end is typically placed upside down), after which the container bottom  111  is applied. The dispenser is now filled and ready for use. Alternatively, it is possible that the bottom is provided with a filling opening, sealed with a removable stop, so that it is not necessary to remove the entire bottom for refilling. 
     In use, operation is as follows. 
     In use, the container  110  will be standing upright, in the orientation shown in the figures. Variations are possible, for instance wall-mounted embodiments, but still the orientation will be upright. 
     Starting from the normal position ( FIG. 2 ), the user presses the dispenser head  120  down. The dispenser head  120  will move down, together with the mixing chamber  140  and the seal member  150 , but the piston member  170  keeps its position. The valve member  190  floats, i.e. there is no net force pressing it down on the bottom  151  of the seal member  150 . This phase continues until the inner surface of the annular sealing portion  155  abuts the upper edge of the cup wall  174  of the piston member  170 , as shown in  FIG. 3 . In this position, the annular sealing portion  155  still seals against the upright portion  114 . 
     In a second phase, the user presses the dispenser head  120  down further, so that the seal member  150  will push down the piston member  170 . The annular sealing portion  155  releases the upright portion  114 , and the dispenser head  120  is pushed down further. It may be assumed that the container  110  is not 100% filled with the substance  4 : the container  110  is filled with substance up to a certain level, and above that level the container  110  contains air. The downwards displacement of the piston member  170  causes the air pressure within the container  110  to rise, and the increased air pressure pushes the substance  4  up through the tube  109 . The substance  4  passes along the valve stem  192  and the valve head  191 , through the opening(s)  143  in the bottom  141  of the mixing chamber  140  (see arrow A). In this condition, the valve head  191  may abut the bottom  141  of the mixing chamber  140 ; for allowing the substance to pass the valve head  191  towards the entrance opening  143  of the mixing chamber  140 , a suitable profiling such as radial ridges and/or grooves may be provided on the upper surface of the valve head  191  and/or on the lower surface of the mixing chamber bottom  141 . 
     Simultaneously, air from the container  110  is allowed to reach the mixing chamber  140  (see arrow B). The mechanism comprises an air chamber  180  between the piston  170  and the seal member  150 . The piston cup  173  has one or more first air passageways  181 , either in the lower cup wall portion  174   b  and/or in the cup bottom  175  outside the cylindrical mount  177 , through which the air chamber  180  communicates with the interior of the container below the piston. The bottom  151  of the seal member  150  has one or more second air passageways  182 , through which the air chamber  180  communicates with the interior of the upper portion of the seal member  150 . The second air passageway  182  is blocked by the valve head  191  in its rest position. 
     The air and the substance mix with each other, already when passing the valve head  191 , and finally in the mixing chamber  140 , to form the desired foam, that is pressed out through the dispense pipe  125 . The mixing meshes  145 ,  146  assist in giving the foam the desired consistency. 
     It is noted that ambient air is allowed into the part of the container above the piston member  170 , through a first venting gap  211  between the inner surface of the upright portion  114  of the top  113  and the outer surface of the seal member  150 , as indicated by arrow C. 
     Foam is pressed out as long as the dispenser head  120  is travelling down. The down stroke of the dispenser head  120  ends when the lower end of its wall  122  abuts the bottom  116  of the recess  117 ; this situation is shown in  FIG. 4 . 
     When the user reduces the down force on the dispenser head  120 , the dispenser head  120  and the piston member  170  remain stationary and the flow of foam out of the dispense pipe  125  stops as soon as the pressure in the container below the piston member  170  has become equal with ambient pressure. 
     When the user takes away all down force on the dispenser head  120 , the spring  130  will push the dispenser head  120  upwards. The dispenser head  120  will travel up together with the seal member  150 , while the piston member  170  remains stationary. The inner surface of the annular sealing portion  155  comes free from the upper edge of the cup wall  174  of the piston member  170 , causing the interior of the container  110  (below the piston member  170 ) to communicate with the ambient air via said first venting gap  211  and a second venting gap  212  between the annular sealing portion  155  and the cup wall  174 , as shown in  FIG. 5 . 
     The seal member  150  travels up to close the gap with the valve member  190  (see  FIG. 5 ), and travels further while taking along the valve member  190 , until the valve member&#39;s stem head  193  contacts the fixation fins  179  of the piston member  170  (see  FIG. 6 ); from this moment on, the travelling seal member  150  also takes along the piston member  170 , while the pressure blow the piston member  170  remains equal to ambient pressure by air flow via said venting gaps  211  and  212  and passageway  181  (see arrow D). 
     Venting is stopped when the annular sealing skirt  155  comes into contact with the upright portion  114  (see  FIG. 7 ). This happens shortly before the dispenser head  120  reaches the end of its upstroke. This will also prevent substance from leaking away. 
     Thus, it will be understood that the mechanism comprises a first flow channel  301  for the foamable substance  4  extending from the substance compartment  210  to an entrance opening  143  of the mixing chamber  140 , with a first valve member  401  arranged in the first flow channel  301 , the first valve member  401  having a non-closed condition and a closed condition for blocking the first flow channel. The wording “non-closed” is used to indicate that it is not necessary for the valve to have a position where the passage is really “open”, since it is sufficient that the valve allows flow in the channel. It is further noted that the valve, in its “non-closed” condition, does not necessarily have to allow for two-directional flow, such as an “open” valve would do: it is sufficient if the valve allows flow in an upwards direction, from the substance compartment  210  to the mixing chamber  140 . In the following, as an alternative to the wording “non-closed”, the wording “free” will be used. 
     The first flow channel  301  comprises the dip tube  109 , with has its lower end arranged for immersion in the foamable substance. In the embodiment shown, the first flow channel  301  extends through the opening  176  in the piston  170 , via the lower portion  157  of the seal member  150 , the first passage opening  156 , past the valve head  191  towards the mixing chamber  140  (see arrow A in  FIG. 4 ). The first valve member  401  is arranged between said opening  176  and the mixing chamber  140 . In the embodiment shown, the first valve member  401  is embodied by the valve head  191 , which closes the first flow channel  301  as long as it abuts the bottom  151  of the seal member  150 , which constitutes the valve seat for the first valve member  401 . 
     It will further be understood that the mechanism comprises a second flow channel  302  for air extending from the substance compartment  210  to an entrance opening  143  of the mixing chamber  140 , with a second valve member  402  arranged in the second flow channel  302 , the second valve member  402  having a free condition for allowing air flow from the substance compartment  210  to the mixing chamber  140 , and a closed condition for blocking the second flow channel. An entrance opening of the second flow channel  302  is at a higher level in the substance compartment  210  than an entrance opening of the first flow channel  301 . In the embodiment shown, the second flow channel  302  extends through the vent opening  181  in the piston  170 , the air passageway(s)  182  in the bottom  151  of the seal member  150 , past the valve head  191  towards the mixing chamber  140  (see arrow B in  FIG. 4 ). In the embodiment shown, the second valve member  402  is embodied by the valve head  191 , which closes the second flow channel  302  when it abuts the bottom  151  of the seal member  150 , which constitutes the valve seat for the second valve member  402 . 
     It will further be understood that the mechanism comprises a third flow channel  303  for air extending from the air compartment  220  of the container  110  to the substance compartment  210  of the container  110 , with a third valve member  403  arranged in the third flow channel  303 , the third valve member  403  having an open condition and a closed condition for blocking the third flow channel. In the embodiment shown, the piston  170  comprises an air chamber  180 . The air chamber  180  communicates with the substance compartment  210  via the vent opening  181  in the piston  170 . The air chamber  180  communicates with the mixing chamber  140  via the air passageway  182 . The air chamber  180  communicates with the air compartment  220  via the second venting passage  212  between the annular sealing portion  155  of the seal member  150  and the cup wall  174 . The third flow channel  303  extends through the second venting passage  212 , the air chamber  180 , and the vent opening  181  (see part of arrow D in  FIG. 6 ). In the embodiment shown, the third valve member  403  is embodied by annular sealing portion  155  of the seal member  150 , which closes the third flow channel  303  when it abuts the upper edge of the cup wall  174 , which constitutes the valve seat for the third valve member  403 . 
     It will further be understood that the mechanism comprises a fourth flow channel  304  for air connecting the air compartment  220  of the container  110  to the exterior of the container  110 , with a fourth valve member  404  arranged in the fourth flow channel  304 , the fourth valve member  404  having an open condition and a closed condition for blocking the fourth flow channel. In the embodiment shown, the fourth flow channel  304  extends from the surroundings, via the first venting gap  211  between the inner surface of the upright portion  114  of the top  113  and the outer surface of the seal member  150 , to the air compartment  220 , as indicated by arrow C in  FIG. 4 . In the embodiment shown, the fourth valve member  404  is embodied by annular sealing portion  155  of the seal member  150 , which closes the fourth flow channel  304  when it abuts the inner surface of the upright portion  114  of the top  113 , which constitutes the valve seat for the fourth valve member  404 . In the rest condition, annular sealing portion  155  is abutting the inner surface of the upright portion  114 . When making the transition from the rest condition to the initial actuation condition, annular sealing portion  155  is sliding along the upright portion  114  and keeps the first venting gap  211  closed. 
     In the above embodiment, the dispensing mechanism is integrated with the container. It is however also possible to have an embodiment where the dispensing mechanism is implemented as a unit to be attached, advantageously screwed or snapped, onto a separate container. An example is schematically illustrated in  FIG. 8A . The figure shows a dispensing mechanism  600 , that is identical to the mechanism described in the above, with the exception that the upper part of container  110  is replaced by a screw cap  610 . The top structure of the screw cap  610  is identical to the top structure of the container of the first embodiment, therefore the same reference numerals are used, and a repeated description is omitted. The screw cap  610  has a cylindrical wall  612 , that is provided with a threaded portion  614 , designed to mate with a threaded neck of a separate container (not shown for sake of simplicity). Such separate container may for instance be a plastic or glass bottle. The design is such that, when fitted on such container, the screw cap  610  forms a substantially airtight connection with the container. For instance, a shoulder portion  613  between the cylindrical wall  612  and the threaded portion  614  may abut the upper edge of the container neck. It should be clear that operation is the same as above, with the exception that filling of the container and subsequently screwing the cap  610  is easier; further, it is easier to unscrew the cap  610  for the purpose of refilling the container. 
     In principle, the threaded portion  614  may be attached to the cylindrical wall  612  at any level, for instance at the lower end thereof (as shown in  FIG. 8A ), or at a higher level (as schematically illustrated in  FIG. 8B ), and the shoulder portion  613  may even be flush with the top  113  (as schematically illustrated in  FIG. 8C ). 
     Instead of a screw cap, the cap may for instance be a snap cap, or the cap may be fitted to the container in another manner. 
     It is noted that, once the piston  170  is arranged in the cap  610 , it is possible that the cap  610  is provided with a cap bottom at the lower end of its wall  612 , for instance by a snap fit or a screw fit or the like. It will then be readily recognizable that the cap  610  has an interior space divided by the piston  170  in an “upper” cap compartment above the piston and a “lower” cap compartment between the piston and the cap bottom. Such cap bottom, however, is not a closed bottom as it will leave a passage for allowing tube  109  to pass, and this passage has sufficient clearance, and/or there will be at least one further passage in such cap bottom, for allowing the “lower” cap compartment to communicate with the interior of a container on which the cap is placed. For sake of convenience, and even without such cap bottom, said compartments will be indicated as “air compartment” and “substance compartment”, in conformity with the previously discussed embodiment. 
     Whether in the form of the integrated container as illustrated in  FIGS. 2-7 , or in the form of the separate cap as illustrated in  FIGS. 8A-8C , in both embodiments, compared to the prior art, foam transport is not achieved by underpressure but by overpressure. Since the container itself acts as pressure chamber, a separate buffer chamber is not needed any more, which allows a saving on relatively large components. 
       FIG. 9  illustrates the embodiment of  FIGS. 2-7  in more detail, wherein the various stages of operation are shown adjacent each other. The vertical displacement of the mouth piece with respect to the normal state is indicated in millimeters for an exemplary implementation. 
       FIGS. 10A-10E  show these stages in more detail on a larger scale. 
     It should be clear to a person skilled in the art that the present invention is not limited to the exemplary embodiments discussed above, but that several variations and modifications are possible within the protective scope of the invention as defined in the appending claims. For instance, two or more functions may be performed by one single entity, unit or member. Even if certain features are recited in different dependent claims, the present invention also relates to an embodiment comprising these features in common. Any reference signs in a claim should not be construed as limiting the scope of that claim. The cylindrical components do not need to have a circular contour for implementing the present invention, although such contour is preferred. 
     Instead of an embodiment where the mouth piece is manipulated to actuate the piston  170 , it is also possible to have a fixed dispenser outlet and a separate movable actuator for actuating the piston. 
     Further, instead of an embodiment with a flexible dip tube having its top end attached to the piston and its lower end lying loose at the bottom of the container, it is also possible to have a telescopic dip tube having at least two rigid telescopic tube components, an upper tube component having its top end attached to the piston and a lower tube component having its lower end attached to the bottom of the container, the upper and lower component being telescopically arranged within each other and being axially aligned with the piston. In such case, it is even possible that the upper tube component has its upper end telescopically arranged within a lower tube component  177  of the piston  170 . It is even possible that the dip tube is a rigid tube having its lower end attached to the bottom of the container and having its upper end telescopically arranged within a lower tube component  177  of the piston  170 . 
       FIG. 11  is a figure comparable to  FIG. 2 , showing a variation of a dispenser  1000 , in which the spring  130  has been integrated with the dispenser head  120 : the dispenser head  120  itself has here a resilient head portion  1230 , preferably implemented as a bellows portion. The lower side of the dispenser head  120  rests against the container  110 . The resilient head portion  1230  can be a separate item, or the dispenser head  120  with the resilient head portion  1230  can be formed as an integral one-piece whole. In either case, the resilient head portion  1230  can be formed of the same material as the remainder of the dispenser head  120 , which is advantageous in the manufacturing process.