Abstract:
A pen comprising an applicator tip, a chamber for receiving the applicator tip in a rest position, wherein the chamber has a first through opening through which the applicator tip passes for moving from the rest position into an operative position, and a closure for closing the first through opening. In accordance with the invention the closure is on an outside of the chamber.

Description:
BACKGROUND OF THE INVENTION 
     The invention concerns a pen comprising an applicator tip, a chamber for receiving the applicator tip in a rest position, wherein the chamber has a first through opening through which the applicator tip passes for moving from the rest position into an operative position, and a closure for closing the first through opening. 
     Pens of the above-indicated kind are known, for example from US No 2004/0265035 A1. In that arrangement the closure which is in the fashion of a sliding door is disposed within the chamber. The sealing function results from a wedge-shaped configuration. More specifically, upon closure, the wedge-shaped part is drawn between two walls. Such a wedging configuration, for closure and even more for opening, requires the application of a considerable amount of force which has to be applied by pressure on the sliding door. In that situation buckling of the sliding door which is of a wall configuration is inevitable. It can also not be suppressed by the sliding door being guided in a gap. At least buckling cannot be prevented into the space where the sliding door has a slot for the applicator tip to pass therethrough. 
     U.S. Pat. No. 4,759,640 discloses a pen which, for closing the through opening of the chamber, has a pair of flaps (plastic material portions) which are formed integrally with the chamber. They are disposed within the chamber. So that the delicate writing tips do not touch the surfaces of those flaps upon activation/deactivation of the pen (by a pusher mechanism), complicated and expensive encapsulation of the ink reservoir used in the pen (it urges the flaps open) and precise geometrical matching of the portions which are in contact with each other are necessary. 
     In the pen in accordance with U.S. Pat. No. 6,033,141 the closure is in the form of an elastic, annular, inwardly curved, slotted seal which is disposed within the chamber. Activation/deactivation of the pen can be effected by a pusher mechanism or by a rotary mechanism, wherein the applicator tip is in direct contact with the seal when passing through the through opening because it has to press the seal open. Besides contamination of the seal that also suffers from the disadvantage that the applicator tip is mechanically stressed at each change in its operating condition, at the peripheral surface thereof. That is increasingly the case, the harder the seal. If the seal is made softer, there is the threat of losses of plasticisers in the seal material. 
     The object of the invention is to develop the pen known from US No 2004/0265035 A1 in such a way that adverse effects in relation to the closure when changing the operating condition thereof are avoided and nonetheless satisfactory sealing of the chamber in the rest condition is achieved. 
     In accordance with the invention the specified object is attained in that the closure is on an outside of the chamber. 
     In other words, in accordance with the invention, the chamber is sealed off from the outside and not from the inside, as is the case in US No 2004/0265035 A1. That design configuration has considerable mechanical advantages in terms of a change in the operating condition. In addition, in the case of an outwardly disposed closure, it is easier to ensure a reliable sealing function. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention preferably the closure is adapted to be moved transversely with respect to a normal of the first through opening to close the first through opening. In other words it is pushed like a sliding door outside the chamber over the first through opening in order to close the first through opening. 
     In order to ensure the sealing function in respect of the closure, it is further preferred in accordance with the invention if the closure is biased in a closure position in the direction of closing the first through opening. In the case of a closure which is disposed externally in relation to the chamber, that biasing effect is mechanically substantially easier to implement than if the closure were within the chamber. 
     As a mechanically particularly simple implementation in accordance with the invention it is preferred if the closure at least portion-wise embraces a region of the chamber, that surrounds the first through opening, and the closure is subjected to a tensile loading for the biasing action. 
     In that case it can be provided in accordance with the invention that the closure has a first abutment which bears against a second abutment that is held immovably with respect to the chamber when the closure closes the first through opening. In that case, in the event of the closure being subjected to a tensile loading, the second abutment serves as a support means. 
     In accordance with a particularly preferred embodiment of the invention there is provided an elastic device for biasing the closure. Such a solution is superior to other biasing principles such as for example a wedging action or the like. 
     In accordance with a particularly preferred embodiment of the invention the elastic device is a spring, in particular a coil spring. That provides a mechanically particularly simple solution. 
     It is further preferably provided in accordance with the invention that the elastic device serves to move the applicator tip from the operative position into the rest position. 
     In other words, in accordance with that solution, the elastic device has two functions to perform, namely on the one hand biasing the closure and on the other hand moving the applicator tip from the operative position into the rest position. That reduces the number of components. 
     Preferably the elastic device is supported at one end against the chamber and at the other end against a support means. In particular supporting the elastic device at the chamber reduces the number of components because no additional components are required for supporting purposes. 
     In accordance with the invention the support means is further preferably a reservoir for a medium to be applied with the applicator tip. 
     In turn that solution again serves to reduce the number of components. When it is implemented, the reservoir moves together with the applicator tip on the one hand with respect to the chamber on the other hand, to change the operating condition. That avoids relative movement of the applicator tip with respect to the reservoir. 
     Further preferably the closure is coupled to the support means to produce the tensile stress. Accordingly a dual function is also attributed to the support means, namely on the one hand supporting the elastic device and on the other hand applying the tensile stress to the closure. 
     Preferably in accordance with the invention the chamber has a second through opening, through which extends a device for feeding to the applicator tip a medium to be applied. That solution is advantageous in particular when the chamber is to be kept small and accordingly is not to accommodate the entire feed means. 
     In that respect further preferably in accordance with the invention there is provided a seal for sealing off the feed device in the second through opening. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is described in greater detail hereinafter by means of a preferred embodiment with reference to the accompanying drawing in which: 
         FIG. 1  is a diagrammatic view in longitudinal section of a pen in accordance with a preferred embodiment of the invention, more specifically in a rest position, 
         FIG. 2  shows the same view as  FIG. 1  but in an operative position, 
         FIG. 3  diagrammatically shows a partial view on an enlarged scale of  FIG. 1 , 
         FIG. 4  diagrammatically shows a partial view on an enlarged scale of  FIG. 2 , and 
         FIG. 5  shows an axial view of the pen in the operative position in accordance with  FIGS. 2 and 4 . 
     
    
    
     DETAILED DESCRIPTION 
     The pen illustrated in the drawing includes an applicator tip  10  which is communicated by way of an ink conductor  12  to a reservoir  14  for ink. The pen also includes a casing  16  in which a chamber  18  is immovably held. The chamber  18  has two through openings  20  and  22 . The ink conductor  12  extends through the through opening  22 . It is sealed off by means of a sealing ring  24 . An abutment  26  which is also stationary with respect to the casing  16  is provided internally on the casing  16 . 
     In contrast to the chamber  18  the reservoir  14  is held axially displaceably with respect to the casing  16 . Disposed between the chamber  18  and the reservoir  14  is a spring  28  which is subjected to a compression loading, for which reason it urges the reservoir  14  towards the right in  FIGS. 1 through 4  within the casing  16 . 
     The pen further includes a push knob  30 , a switching crown  32  and a switching star member  34 . Those elements belong to a pusher mechanism which is widely used in the field of writing implements and therefore does not have to be described in greater detail. 
     Finally the pen illustrated in the drawing includes a closure diaphragm  36  which is fixed with its one end to the reservoir  14 , in particular being injection molded thereto, while a further abutment  38  is provided at the other end thereof (the free end). 
     In the rest position shown in  FIGS. 1 and 3  the applicator tip  10  is disposed within the chamber  18 . In that position the closure diaphragm  36  closes the through opening  20  because it extends over that region of the chamber  18 , in which the through opening  20  is provided. As the closure diaphragm  36  bears with its abutment  38  against the abutment  26 , it cannot be pulled away by the return force of the spring  28  out of the region of the chamber, that surrounds the through opening  20 . Rather, it is subjected to a tensile loading because the spring  28  presses against the reservoir  14  and accordingly the reservoir  14  pulls on the closure diaphragm  36 . 
     In that position, that pressing force with which the closure diaphragm  36  is pressed on the outside on to the chamber  18  is inversely proportional to the radius of the outside contour of the chamber  18  around the through opening  20 . Accordingly, the pressing force of the closure diaphragm  36  against the chamber  18  can be suitably adjusted by an appropriate choice of that radius, in particular in such a way that the closure diaphragm  36  sufficiently sealingly closes the chamber  18  or the through opening  20 . As moreover the through opening  22  of the chamber  18  is closed by means of the sealing ring which bears sealingly against the ink conductor  12 , the applicator tip  10  is reliably prevented from drying out. 
     By pressure applied to the push knob  30  and axial displacement thereof with respect to the casing  16 , the pen is moved out of the rest position shown in  FIGS. 1 and 3  into the operative position shown in  FIGS. 2 ,  4  and  5 . In comparison with the rest position, the push knob  30 , the switching crown  32 , the switching star member  34  and the reservoir  14  together with the ink conductor  12  and the tip  10  have been displaced towards the left in  FIGS. 1 through 4  with respect to the casing  16  and the chamber  18 , in the operative position. As the closure diaphragm  36  is designed in the fashion of a ‘sliding door’ and therefore has sufficient flexibility for fitting snugly to the chamber  18  from the outside, but on the other hand has sufficient stiffness to be displaced overall by mere displacement of the reservoir  14  towards the left in  FIGS. 1 through 4 , the closure diaphragm  36  slides along the outside of the chamber  18  and in particular the abutment  38  is displaced towards the right in  FIGS. 1 through 4  with respect to the abutment  26 . For that purpose, the closure diaphragm  36  slides in a guide (not shown in the drawing) against the chamber  18  so that it can be displaced from the rest position into the operative position only by being pushed by means of the reservoir  14 . As a result another region of the closure diaphragm  36  moves into that region of the chamber  18 , in which the through opening  20  is formed. The closure diaphragm  36  also has a through opening  40  in that region which now at least partially coincides with the through opening  20 . 
     In the operative position shown in  FIGS. 2 ,  4  and  5  the ink conductor  12  extends through both the through opening  20  of the chamber  18  and also the through opening  40  of the closure diaphragm  36 , for which reason the applicator tip  10  in that position is outside the chamber and also outside the casing  16 . 
     If the push knob  30  is actuated in the operative position shown in  FIGS. 2 ,  4  and  5 , the spring  28  moves the pen back into the rest position shown in  FIGS. 1 and 3  again. 
     That region of the outside wall of the chamber, which surrounds the through opening  20 , can be made from a flexible material or covered therewith, for example in the form of a sealing ring, in order to improve the sealing function. That makes it possible to achieve an adequate sealing action even when a low level of tensile stress is involved. 
     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 its various embodiments.