Abstract:
An applicator device comprising a casing and an application element wherein the application element is displaceable with respect to the casing against a return force.

Description:
BACKGROUND OF THE INVENTION 
     The invention concerns an applicator device comprising a casing and an application means. 
     Applicator devices of that kind are known. They involve for example ballpoint pens. If such an applicator device is used on a substrate which is easily displaceable in the application plane, then conventional applicator devices are not suitable for application thereon because folds are thrown up, that is to say raised portions, which stand up out of the plane of the substrate. The difficulty of producing on such a substrate a uniform application such as for example a line of a constant line width are similarly high as in the case of a substrate which is structured from the outset—in such a way as to be perceptible to the eye. 
     The object of the present invention is to improve the applicator device of the kind set forth in the opening part of this specification, such that it is suitable for substrates which are displaceable in the application plane as well as for structured substrates. 
     SUMMARY OF THE INVENTION 
     The foregoing object is attained in accordance with the present invention wherein the application means is displaceable with respect to the casing against a return force. The invention relates in particular to an applicator device for a cosmetic product. 
     When the applicator device according to the invention is applied to an easily displaceable substrate such as for example to the skin or a textile-like surface, the application means can elastically recoil in the axial direction without requiring the collaborative involvement of that person who is guiding the applicator device. Particularly when used on the skin, that has the advantage that the male or female user still has to concentrate only on positioning in the plane of the skin. In addition, the risk of injury is minimised in the case of uses in the proximity of the eye. 
     If the attempt is made to produce a line of constant line thickness on a structured substrate such as for example a textile article or on crepe paper, then the applicator device according to the invention can be guided at a constant spacing which is less than the set spring travel. By virtue of the elastically resilient properties, the applicator device provides for self-regulating compensation in respect of the application plane-casing spacing and thus ensures a line of constant width. In addition the resilient arrangement reduces or entirely eliminates the risk of folds or wrinkles being formed because the force in the application direction is minimised by virtue of the applicator means yielding. 
     In a situation involving the application of products to the skin, that virtually self-regulating mechanism affords the advantage that the pressure of the application means on the skin is approximately constant at any time and is independent of the spacing of the casing relative to the surface of the skin, at any event within the regulating range for the spring effect. The user is also freed of precisely maintaining the casing-skin spacing and can be certain of uniformly achieving the desired line thickness. 
     That virtually self-regulating mechanism can be adjusted by suitable adjustment of the maximum free travel length and the effective spring constant, within relatively wide ranges. In that way it is easily possible to provide for adaptation to the properties of a structured and/or easily displaceable substrate, in regard to the length of the spring travel. 
     In a preferred feature of the invention the application means is displaceable with respect to the casing by between 0.05 mm and 10 mm, preferably between 0.05 mm and 2 mm, further preferably between 0.2 mm and 0.5 mm. 
     In a further preferred feature of the invention the return force is between 0.03 N and 50 N, preferably between 0.03 N and 10 N, further preferably between 0.03 N and 0.5 N. 
     In accordance with a further preferred feature of the invention it is provided that the application means has a ball and the quotient of the return force and the equatorial cross-sectional area of the ball is between 4 Pa and 6 GPa, preferably between 40 Pa and 1 GPa, further preferably between 10 kPa and 7 MPa. 
     In accordance with an embodiment of the invention which is preferred as being particularly simple there is provided at least one elastic element for producing the return force. 
     In a further preferred feature the elastic element is a spring. 
     An embodiment which is particularly simple and therefore further preferred in accordance with the invention is one in which the elastic element is a coil spring. 
     It is preferred in accordance with the invention for the elastic element to comprise a polymer material. That provides that the elastic element is particularly simple and inexpensive to produce. In addition it is light. 
     In accordance with a particularly preferred embodiment of the invention the applicator device has a storage means for a product to be applied, wherein it is further provided that the elastic device belongs to an increased pressure-producing device and is adapted to press with its elastic return force against a boundary means of the storage means to produce an increased pressure in the storage means. 
     In other words, there is provided an elastic device which serves two kinds of purposes, namely on the one hand elastic biasing of the application means against axial displacement with respect to the casing and on the other hand production of an increased pressure in the storage means. That reduces the total number of individual parts, which overall simplifies the application means. 
     In accordance with a further preferred feature of the invention it is provided that the increased pressure-producing device is controllable in the sense of a reduction in the pressure in the storage means. 
     Such a fall in pressure can involve a relief in load on the elastic device, thereby in turn affording the possibility of using a polymer material for the elastic device, with the advantages already set forth hereinbefore. 
     In accordance with a further preferred embodiment of the invention it is provided that the increased pressure-producing means has a transmission means with at least one female screwthread element and at least one male screwthread element, wherein the transmission means can assume at least two operating conditions, namely a first operating condition in which the two screwthread elements mesh with each other to produce the increased pressure, and a second operating condition in which they do not mesh with each other, thereby resulting in a reduction in the increased pressure. 
     In other words, in accordance with this preferred embodiment of the invention, it is provided that two screwthread elements are coupled together to produce the increased pressure and are uncoupled to reduce the pressure in the storage means. This therefore affords a solution which is particularly simple from the point of view of structure, inexpensive and easy to handle. 
     It can happen that a user of the applicator device forgets to reduce the pressure in the storage means after work has been done. In such a case, under some circumstances, the product which is to be applied can suffer from damage in the storage means. In addition it is not possible to be sure that the product will not escape. 
     In accordance with a particularly preferred embodiment of the invention it is therefore provided that the applicator device can assume at least two operating conditions, namely a rest condition and a use condition, and has a means for reducing the pressure in the storage means, said pressure-reducing means being responsive to a movement of the applicator device from the use condition into the rest condition. In other words, this configuration of the invention provides that the pressure in the storage means is reduced automatically as soon as the applicator device—after its work has been done—is put into the rest condition. 
     In that respect it can be provided that the applicator device is changed from the use condition into the rest condition by screwing on a cap. Instead of screwing on the cap, the cap can also be fitted on and fixed by means of a bayonet connection. 
     That therefore embodies a substantially ‘automatic’ mechanism. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is described in greater detail hereinafter by means of a preferred embodiment by way of example with reference to the accompanying drawing in which: 
         FIG. 1  is a diagrammatic view in longitudinal section of a pencil according to a particularly preferred embodiment of the invention, 
         FIG. 2  shows a partly sectional view of a plunger of the pencil of  FIG. 1 , 
         FIG. 3   a  shows the control pushrod of the pencil of  FIG. 1  and  FIG. 3   b  is a partial sectional view taken along line A-A of  FIG. 3   a,    
         FIG. 4  shows a diagrammatic view of a lead or cartridge casing portion of the pencil of  FIG. 1 , 
         FIG. 5   a  shows a front part of the pencil of  FIG. 1  and  FIG. 5   b  is a sectional view taken along line A-A of  FIG. 5   a,    
         FIG. 6   a  shows the pencil of the present invention in a non-operating condition, 
         FIG. 6   b  is an enlarged view of area A of  FIG. 6   a,    
         FIG. 6   c  is a sectional view taken along line A-A of  FIG. 6   d,    
         FIG. 6   d  is an enlarged view of area B of  FIG. 6   a,    
         FIG. 7A  shows the pencil of the present invention in an operating condition ready to write, 
         FIG. 7   b  is an enlarged view of area A of  FIG. 7   a,    
         FIG. 7   c  is a sectional view taken along line A-A of  FIG. 7   d,    
         FIG. 7   d  is an enlarged view of area B of  FIG. 7   a,    
         FIG. 8   a  shows the pencil in a slightly different operating position than  FIG. 7   a  as described in paragraph, 
         FIG. 8   b  is an enlarged view of area A of  FIG. 8 , 
         FIG. 8   c  is a sectional view taken along line A-A of  FIG. 8   d,    
         FIG. 8   d  is an enlarged view of area B of  FIG. 8   a , and 
         FIGS. 9   a  and  9   b  show the front and rear parts of the pencil in an operating condition where the tip is axially displaced at a maximum with respect to the shaft  10 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to the figures, the pencil has an outer shaft  10  which serves as a casing and on to which a cap  12  can be screwed. For that purpose there is provided a screwthread identified by reference numeral  14 . The cap  12  has a seal  16  which sealingly embraces a tip  18  of the pencil in the screwed-on condition. A ball  20  is held at the free end of the tip  18 . A row of teeth  19  on the cap  12  and a ring of teeth  21  on the pencil serve for rotationally coupling the cap  12  to the tip  18  when it is screwed on. 
     At its end portion remote from the ball  20  the tip  18  is fitted on to a lead or cartridge casing portion  22 . In that region the tip  18  is of a circular internal contour and the casing portion  22  is also of a circular external contour, thus affording a slipping clutch. 
     The internal space of the casing portion  22  forms a storage means  24  for ink  26 . Arranged on the side remote from the ball  20  in the storage means  24  is a closure mass which serves for sealing off in relation to the ambient atmosphere. The rear boundary of the storage means  24  is formed by a plunger  30 . A control pushrod  34  projects into the plunger  30 . A spring  36  bears on the one hand against the control pushrod  34  and on the other hand against a closure cap  38 . The spring  36  is a polymer spring. It can also be of metal or other suitable material. 
     As can be seen from  FIG. 2  provided on the plunger  30  is a helical incision  40  whereby the plunger is variable in respect of its length. As a result it represents a trailing plunger. 
     At its end portion remote from the tip  18  the plunger  30  has projections  44  and  46  which for rotational coupling purposes engage into corresponding recesses in the casing portion  22 . Accordingly the plunger  30  is admittedly rotationally coupled to the casing portion  22  but it is held axially slidably therein. 
     Also at its end portion remote from the tip  18  the plunger  30  is provided in its interior with two substantially hemispherical female screwthread elements of which one is denoted by reference  48  and which serve for coupling—at times—to the control pushrod  34 . 
     The control pushrod  34 , as shown in  FIGS. 3   a  and  3   b , is provided with male screwthread elements which are complementary to the female screwthread elements  48  and of which one is identified by way of example by reference  50 . The male screwthread elements  50  correspond to segments of a helical groove and respectively extend over an angle of somewhat more than 300°. They are interrupted by a longitudinal groove  52  which extends over an angle of about 27°. 
     At its end portion remote from the tip  18  the control pushrod  34  is provided with projections  54 ,  56 ,  58  and  60  which engage into corresponding recesses in the external shaft  10  for rotational coupling purposes. The control pushrod  34  is however slidable axially with respect to the external shaft  10  between the closure cap  38  and an abutment  62 . 
     The function of the pencil illustrated in the drawing is as follows: 
     With reference to  FIGS. 6   a  through  6   d , when the cap  12  is screwed on to the external shaft  10 , the female screwthread elements  48  are in the groove  52 . Accordingly, in that operating position, there is no coupling between the control pushrod  34  and the plunger  30 . The plunger  30  therefore does not apply any pressure to the closure mass  28  or the ink  26 . That is important in regard to inks and/or closure masses which are adversely affected by a permanent pressure. The spring  36  is relieved of stress when the cap  12  is screwed on to the external shaft  10 . It is therefore possible to use a polymer spring. More specifically, when using a polymer spring, permanent stressing would lead to material fatigue. 
     With reference to  FIGS. 7   a  through  7   d , when the cap  12  is rotated with respect to the external shaft in order to unscrew it, then, because of the rotational coupling between the row of teeth  19  and the ring of teeth  21 , the tip  18  also rotates. The plunger  30  therefore also rotates. In the further course of the rotary movement, shown in  FIG. 7   c , the female screwthread elements  48  leave the groove  52  and pass into the male screwthread element  50 . Further rotary movement in that condition provides that the female screwthread elements  48  travel along the male screwthread element  50 , whereby the control pushrod  34  which hitherto has been supported against the projection  62  is displaced against the spring  36 . It is only now that the spring  36  is stressed. As a result the elastic return force of the spring  36  acts by way of the control pushrod  34  on the plunger  30 , whereby the pressure in the storage means  24  rises. At its end, the male screwthread element  50  is limited by an abutment  64  against which the female screwthread elements  48  butt upon further rotary movement. If nonetheless the rotary movement is continued, then the slipping clutch formed between the casing portion  22  and the tip  18  slips so that the pressure in the storage means  24  does not rise further. That is therefore kind to a possibly pressure-sensitive ink. 
     The increased pressure which is now built up in the storage means  24  can be used for discharging the ink  26 . 
     When, after use of the pencil, the cap  12  is screwed on to the external shaft  10  again, the female screwthread elements  48  travel back along the male screwthread element  50  into the groove  52  again, because of the coupling effects described in detail hereinbefore. As a result, under the influence of the spring  36 , the control pushrod  34  travels again towards the abutment  62  where it is supported. Accordingly the spring  36  no longer acts on the ink  26  by way of the plunger  30 . In that condition there is no longer any increased pressure prevailing in the storage means  24 , which is advantageous in terms of protecting the ink  26  and in regard to the aspect of anti-leakage safeguard. In addition the spring  36  is also protected. 
     When the cap  12  is screwed on to the external shaft  10  the plunger  30  is moved away from the ball  20  until the female screwthread elements  48  pass into the groove  52 . So that in that situation the plunger  30  does not suck the ink  26  out of the tip  18 , the plunger  30  is provided with the helical incision  40  and as a result is in the form of a trailing plunger. More specifically it can increase in length in that situation. 
     Instead of the screwthread  14 , it is also possible to provide a bayonet connection for holding the cap  12  on the external shaft  10 . In that case, under some circumstances, it is possible to forego limiting the increased pressure by means of the abutment, because, when a bayonet connection is involved, that angle through which the two parts which are to be connected together can be rotated relative to each other is in any case limited. 
     For pressure limitation purposes, it can further be provided that the row of teeth  19  comes into engagement with the ring of teeth  21  only over a part of the axial travel of the cap  12  when it is screwed on to the external shaft  10 . 
     The rotary transmission means shown in the drawing can compensate for a reduction in the filling level in the storage means  24 . More specifically, with a decreasing filling level, the plunger  30  gradually moves into the storage means  24 , whereas the control pushrod  34  does not change its position relative to the spring  36  in accordance with the filling level, and for that reason the same return force is always available for producing the increased pressure. 
     Springing of the tip  18  in the axial direction with respect to the external shaft  10  is described hereinafter. 
       FIG. 7   a  shows an operating condition in which the cap  12  is unscrewed and the pencil is therefore in a condition of being ready to write. In particular the control pushrod  34  is coupled to the plunger  30 , the spring  36  is stressed and a corresponding pressure obtains in the storage means  24 . However, still no axial force acts on the tip  18 , from the tip  18 . 
       FIGS. 8   a  through  8   d  show an operating condition which differs from that shown in  FIGS. 7   a  through  7   d  in that a slight axial force acts on the tip  18 . As a result the tip  18  is displaced in the axial direction with respect to the external shaft  10 . As the tip  18  is coupled in the axial direction to the casing portion  22 , the casing portion  22  is also displaced in the axial direction with respect to the external shaft  10 . Because of the coupling of the casing portion  22  by way of the screwthread elements  48 ,  50  to the control pushrod  34 , the control pushrod  34  is also displaced, more specifically against the elastic return force of the spring  36 . Accordingly an elastic return force is operative against axial displacement of the tip  18  with respect to the external shaft  10 . The tip  18  is thus sprung. 
       FIGS. 9   a  and  9   b  show that operating condition in which the tip  18  is axially displaced at a maximum with respect to the external shaft  10 . That condition is reached when the casing portion  22  butts against an abutment  66 . The abutment  66  is provided on an abutment ring  68  which is held axially immovably in the external shaft  10 . The side of the abutment ring  68 , which is in opposite relationship to the abutment  66 , can serve as an abutment for the control pushrod  34 , instead of the projection  62 . 
     In the particularly preferred embodiment of the invention as illustrated in the drawing the polymer spring  36  serves two purposes at the same time, namely on the one hand producing increased pressure in the storage means  24  and on the other hand springing the tip  18  in the axial direction in regard to displacement with respect to the external shaft  10 . 
     The features of the invention disclosed in the foregoing description, the claims and the drawing can be essential both individually and also in any combinations for implementing the invention in the various embodiments thereof.