Abstract:
A roller dispenser for dispensing liquids has a headpiece ( 3 ) mounted on a container ( 1 ) with a barrier component ( 2 ) fitted in between. The barrier component and headpiece ( 2, 3 ) have respective annular seal elements which can fit together to form a plug seal, isolating the underside of the roller ( 5 ) from the liquid supply, when the barrier and headpiece are moved close together. They can be moved apart by a cam action e.g. a thread in order to allow liquid on to the roller.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention has to do with dispensers which apply a liquid from a container onto a surface, e.g. the skin, via a roller.  
         BACKGROUND  
         [0002]    Roller applicators are well-known as such, and conventionally consist of a headpiece which screws or snaps onto the container neck. The headpiece has a part-spherical socket surface in which a plastic ball seats. The bottom and top of the ball are exposed to the liquid in the container and to the exterior respectively. In use the top of the ball is held against the skin and rolled on the skin by pulling the dispenser sideways. Liquid wetting the rear of the ball is then progressively applied to the skin from the front of the ball. The ball needs to be a reasonably close but not tight fit in its headpiece socket, so that on the one hand it can roll freely and liquid on its surface can pass through, but on the other hand the flow of liquid is limited.  
           [0003]    There can be an issue of leakage or evaporation from the roller applicator. It is routine to provide a snap or screw cover cap to cover the headpiece and exposed ball surface when the applicator is not being used. However liquid may still leak or evaporate into the space between ball and cap and hence be wasted. With highly volatile or penetrating liquids this can be a serious problem.  
           [0004]    It has been proposed to prevent such leakage by arranging to clamp the ball down into its headpiece socket when the dispenser is not in use. However extreme precision is needed to get an effective seal between the ball and socket surfaces, and in practice this is not achieved. It has been proposed to include an O-ring to help the seal, but these O-rings are subject to rapid wear and sealing is still poor.  
           [0005]    It would be desirable to provide some new way of addressing the problems of leakage and/or evaporation of liquid in such a dispenser.  
         THE INVENTION  
         [0006]    What we propose, in the context of a device for dispensing liquids comprising a container to hold the liquid and a headpiece on the container having a roller seating in which an applicator roller is retained rotatably with its front surface exposed for applying liquid and its rear surface exposed to a liquid pick-up region, is as follows. A barrier is provided between the container interior and the headpiece, and has one or more flow openings. The barrier and headpiece are movable relative to one another between an open position, in which the one or more flow openings of the barrier communicate(s) with the liquid pick-up region, and a closed position in which the headpiece and barrier engage one another making an internal seal which blocks such communication.  
           [0007]    The relative movement between the open and closed positions is preferably in an axial direction of the dispenser, typically corresponding to the front-to-rear axis of the roller and/or the axis of the container mouth. Naturally the most usual situation has a cylindrical container coaxial with its dispenser roller. It is preferred that the barrier and headpiece are rotatable relative to one another around that axis, and make a cam engagement so that the rotation drives the axial movement necessary for transition between the open and closed positions. They may for example make a bayonet or thread engagement. Preferably there are rotational limit stops so that the user apprehends the operation as a rotational one between defined rotational limit positions for the open and closed states.  
           [0008]    Preferably the barrier is a discrete element secured to the mouth of the container. It is preferred that the barrier is fixed relative to the container and the headpiece movable relative to the container. Whichever of the elements is movable relative to the container preferably has an exposed friction surface e.g. ribs or knurling to help grip it.  
           [0009]    The idea is to create a seal between the barrier and headpiece components upstream of where liquid for pick-up contacts the roller. The preferred form of seal is a plug seal in which an axially-extending sealing surface on a seal component of one of the headpiece and barrier engages slidably with an axially-extending sealing surface on a sealing portion of the other, to achieve the closed position. By having the vector of relative movement parallel to the sealing surfaces, or at a small angle (less than 45°, preferably less than 30°) to one or both of them combined with the possibility of one or both of the sealing portions deforming as they move into sealing engagement, an effective seal can be obtained using modest forces and components which are easy to make e.g. by moulding conventional non-elastomeric materials such as polypropylene.  
           [0010]    Preferably these respective sealing portions move axially into and out of the sealing relation. However as is an alternative they might be rotatable between the two conditions e.g. by providing one or more circumferentially-localised windows which can be brought into or out of register with one another by relative rotation.  
           [0011]    Preferably the sealing portions are both annular, one fitting inside the other. Such an annular seal can divide a space behind the roller into inner and outer zones, one communicating with the flow openings of the barrier and isolated from the liquid pick-up region, the other communicating with (or being) the liquid pick-up region and isolated from the container interior by a closed part of the barrier.  
           [0012]    One of the sealing portions is preferably in the form of a projecting wall or skirt, which is to some extent laterally deformable and has the mentioned zones to either side of it. For an annular seal, preferably at least that seal portion which engages outside the other one is a skirt of this kind which is put under tension by interference with the other portion when they seal together. The other portion may be a second skirt or—preferably, from the point of view of simplicity of manufacture—a simple closed boss, plug or recessed wall which is essentially non-flexing on sealing.  
           [0013]    A preferred embodiment has the barrier with a closed central zone projecting forwardly as a boss having a peripheral radially-outwardly directed annular sealing surface, and an annular peripheral zone having one or more flow openings. The headpiece has a central cavity which provides the pick-up region i.e. is directly exposed to the rear surface of the roller, and a downwardly projecting skirt seal which, by any manner of axial relative movement as mentioned above, can have its inner sealing surface moved into and out of sealing engagement with the annular sealing surface of the barrier&#39;s central boss.  
           [0014]    The reader will appreciate that for both the closed and open positions of the internal seal, liquid on the side of the internal seal opposite from the pick-up region needs to be prevented from escaping to the exterior from between the relatively movable barrier and the headpiece. This external seal can be provided by a sliding seal engagement which maintains its closed, sealed condition in both the open and closed conditions of the internal seal. Preferably an annular, axially-slidable seal engagement between the components is provided inwardly of cam engagements between the two, so that the latter are not wetted. A particularly preferred form—again, in that it can be easy to make and can obviate the use of discrete elastometic seal elements and so forth—is an outer annular plug seal. Like the internal plug seal, this can be formed by respective axially-extending surfaces integral with the headpiece and barrier components. The difference is that the outer plug seal is made with a longer reach so that it remains closed in both the closed and open positions of the interior seal. Preferably one of the two components has an axially-projecting flexible skirt as the seal portion for this outer seal, wiping a substantially cylindrical sealing surface on the other component.  
           [0015]    An embodiment of the invention is now described by way of example, with reference to the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is a side view of a roller dispenser;  
         [0017]    [0017]FIG. 2 is an axial section at B-B of FIG. 1;  
         [0018]    [0018]FIG. 3 is an enlarged detail of the axial section, showing a barrier and headpiece in closed position, and  
         [0019]    [0019]FIG. 4 is a corresponding enlarged view showing the same components in an open position. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0020]    With reference to the figures, a roller applicator is provided on a cylindrical container  1 . The container and other components are all of polypropylene. A barrier closure  2  is fixed into the mouth of the container  1  and located axially by means of a plug  25  with snap ribs and a locating flange  26 . Above the container mouth the closure  2  continues with an upward cylindrical extension  28 , closed over at the top by a barrier web  21 .  
         [0021]    The barrier web  21  is essentially a flat disc with a raised circular boss  22  in its centre and a relatively recessed annular outer zone around this. A series of flow openings  24  is provided through this outer zone. The periphery of the boss constitutes a sealing surface  23  which is also a transition down to the outer zone. This sealing surface has a slight convergence e.g. at from 10° to 20° to the axis.  
         [0022]    Radially outwardly of the openings  24  the upper surface of the web  21  has an integrally-moulded outer sealing skirt  29 . This is a cylindrical component, sufficiently thin to be readily flexed and curved near its edge to provide an outwardly-directed sealing land  291 .  
         [0023]    The upper extension  28  of the closure  2  has a four-start helical thread  27  moulded on its outer surface. A generally tubular headpiece  3  is fitted over the closure barrier  2 . The headpiece  3  has an upper tubular socket extension  32  with a spherical surface region  31  in which a ball  5  is retained rotatably. The ball is snapped into this spherical recess during assembly. Below the socket extension  32  the headpiece  3  has a radially-outwardly projecting web  33  from which three concentric skirts depend. These are a relatively thin and flexible inner sealing skirt  37 , radially aligned above the sealing surface  23  of the closure  2 , a relatively thick and rigid outer sealing skirt  36  which is the same axial length as the inner sealing skirt  37 , and presents a cylindrical inwardly-directed surface aligned to make an interference fit with the flexible seal  29 , 291  of the closure barrier, and a longer outer securing skirt  34  which extends down around the outside of the tubular extension  28  of the closure  2 . This outer securing skirt  34  has an outer surface with friction ribs  35  and an inner surface with inwardly-directed cam lugs (not shown) which engage in the threads  27  on the closure  2 . These threads are blind quarter-turn threads; the headpiece  3  is forcibly snapped into place over the closure sleeve  28  on assembly, whereafter it is held in place and can be rotated only a quarter of a turn. The threads and lugs cooperate so that this quarter turn shifts the headpiece  3  axially between the two positions shown in FIGS. 3 and 4.  
         [0024]    The inner sealing skirt  37  of the headpiece  3  has on its inner surface a tapering lead portion  38  which acts as a sealing surface complementing the tapered sealing surface  23  below. The components are dimensioned so that with the thread tightened down (FIG. 3) the sealing boss  22 , 23  fits tightly into the tapered skirt opening  38  above and with some interference, so that the skirt edge is under tension and makes a good seal. The corresponding part of the thread  27  may be ramped more gently giving a higher mechanical advantage to bring the seal to this tensioned condition and keep it there.  
         [0025]    In this position (FIG. 3) the space beneath the headpiece  3  is sealingly divided by the annular skirt  37  and its engagement with the sealing surface  23  beneath, separating an antechamber  7  (between the inner and outer sealing skirts  37 , 36  of the headpiece) from the pick-up region  6  below the ball  5 . Because the boss  22  has a closed top, the pick-up region  6  is completely isolated from the container interior. At the same time an external seal is provided by engagement of the sealing land  291  of the barrier&#39;s outer sealing skirt  29  with the inner cylindrical surface of the headpiece outer sealing skirt  36 . This prevents liquid from escaping to the outside via the antechamber  7 .  
         [0026]    The tightening movement is limited, to avoid damaging the delicate sealing skirt edges  38 , 291  by over-compression. This may be by appropriate positioning of the thread blinds, by abutment of the end of the short rigid sealing skirt  36  or of the long rigid securing skirt  34  with the opposing surface of the closure  2 , or a combination of these.  
         [0027]    Unscrewing the headpiece  3  through a quarter turn shifts it axially to the FIG. 4 position. Here the headpiece inner sealing skirt  37 , 38  slides clear of the boss  22  beneath, opening up communication from the container interior to the backside  51  of the ball  5 . However the upward outer sealing skirt  29 , with its longer reach, remains in sealing contact with the inward cylindrical sealing surface of the rigid downward skirt  36  on the headpiece, preventing leakage of liquid to the outside.  
         [0028]    After use, a quarter turn of retightening returns to the sealed condition. The tapering of the opposed inner sealing surfaces  23 , 38  guides their meeting to avoid damage, and also by a sliding camming action tensions the outer seal annulus.  
         [0029]    [0029]FIGS. 1, 2 also show a conventional cover cap  4  which can snap onto the headpiece.