Patent Abstract:
A pencil comprising a lead, a cartridge for at least partially receiving the lead, and a protective cap having a device for shaping the lead.

Full Description:
BACKGROUND OF THE INVENTION 
     The invention concerns a pencil comprising a lead, a cartridge for at least partially receiving the lead, and a protective cap having a device for shaping the lead. 
     Pencils of the above-indicated kind are known, for example from DE 196 16 613 C1. In accordance therewith the device for shaping the lead is in the nature of a sharpener. The sharpening operation is effected after fitment of the cap containing the sharpener by rotation of two sleeve portions relative to each other, whereby a rotary drive for the lead is actuated. A slipping clutch serves to limit the advance movement of the lead by the rotary drive. 
     U.S. Pat. No. 2,514,761 discloses a protective cap with integrated sharpener and a holder for a lead pencil. When the holder is rotated with respect to the protective cap with the sharpener, an advance movement of the lead pencil is effected until an abutment is reached. The advance movement is therefore restricted to a predetermined amount. 
     The object of the invention is to develop the pencil of the kind set forth in the opening part of this specification in such a way that handling thereof is simplified. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention for that purpose there is provided a device responsive to fitment of the protective cap onto the cartridge for axial displacement of the lead with respect to the cartridge. 
     In accordance with the invention accordingly the advance movement required for shaping the lead is effected automatically when simply fitting the protective cap onto the cartridge without further measures being required. Handling is thus simplified. 
     The operation of shaping the lead can be effected independently of fitment of the protective cap onto the cartridge. Preferably in accordance with the invention however the device for shaping the lead is responsive to the protective cap being fitted onto the cartridge. In other words, preferably in accordance with the invention, two things happen when the protective cap is fitted onto the cartridge. On the one hand the lead is displaced axially with respect to the cartridge and on the other hand the lead is sharpened. Those two operations do not necessarily have to occur simultaneously. Rather, it can be provided that firstly the lead is axially displaced and then—in a second phase of the fitment procedure—shaping of the lead takes place. 
     In accordance with the invention the fitment operation can involve pushing on and/or screwing on the protective cap. 
     In accordance with the invention the shaping operation includes cutting and/or sharpening the lead. 
     In accordance with a particularly preferred embodiment of the invention the displacement device acts (exclusively) in the sense of pushing the lead out of the cartridge. That ensures that, after the lead has become blunt, a projecting length of the lead beyond the front end of the cartridge is always achieved by the protective cap being simply fitted onto the cartridge. 
     In a further preferred feature there is provided a device for limiting the displacement to a predetermined extent so that, possibly in matched relationship with the shaping device, fitting the protective cap onto the cartridge (and removing it again) leads to the provision of a defined working region of the lead. 
     Preferably in accordance with the invention the limiting device has an abutment on the cartridge. That affords a particularly simple solution. 
     The extent is advantageously between 0.5 mm and 1.1 mm, preferably between 0.6 mm and 1.0 mm, further preferably between 0.7 mm and 0.9 mm. 
     Preferably the pencil according to the invention has a shank which axially displaceably holds the cartridge and a first one-way clutch which couples the lead to the shank and which allows the lead to be pushed out of the cartridge but blocks it to prevent it from being pushed in. In that way the lead advance movement can be effected by displacement of the cartridge with respect to the shank. 
     In a further preferred feature there is provided a second one-way clutch which couples the cartridge to the lead and which allows the lead to be pushed out of the cartridge but blocks it to prevent it from being pushed in. That configuration serves to prevent the lead from moving in opposite relationship to the advance direction with respect to the cartridge when the cartridge is moved into its starting position again after advance movement of the lead has occurred. 
     The first and/or the second one-way clutch can have a pawl mechanism. That once again affords a mechanically particularly simple solution. 
     Preferably in accordance with the invention there is provided a device for biasing the cartridge with respect to the shank. That arrangement provides that, after the advance movement of the lead, the cartridge is automatically returned into its starting position again. 
     Further preferably according to the invention the protective cap has at least one blade for shaping the lead by cutting and/or sharpening. 
     In that case in a further preferred feature of the invention the blade can deflect against an elastic return force in the axial direction of the lead. That prevents an excessively great axial force in the cutting/sharpening operation. 
     However the blade can also be pivotable and/or deformable against an elastic return force. 
     In a particularly preferred embodiment of the invention the protective cap has at least one guide template. That guide template serves for cutting the lead along a predetermined cutting path. 
     In accordance with a particularly preferred embodiment of the invention, once again for absorbing excessive axial forces, it is provided that the guide template can deflect against an elastic return force in the axial direction of the lead. 
     Preferably the device for shaping the lead exerts no force on the lead in a rest position. More specifically for example an ongoing pressure on the lead in the event of prolonged storage or at elevated temperature, would have the result that the tip of the lead is crushed or pinched again after the sharpening operation. 
     In particular for the aforementioned reason, it is preferred in accordance with the invention to provide an axial abutment against which the device for shaping the lead bears in a rest position. More specifically that provides that it applies no force to the lead in the rest position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is described in greater detail hereinafter by means of preferred embodiments with reference to the accompanying drawing in which: 
         FIG. 1  shows diagrammatic views in longitudinal section of an embodiment of the pencil according to the invention in various operating conditions, 
         FIG. 2  shows the same views as  FIG. 1  but of a second embodiment, and 
         FIG. 3  shows the same views as  FIGS. 1 and 2  but of a third embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The pencil shown in  FIG. 1  includes a shank  10 , a cartridge  12 , a stick or lead  14 , a protective cap  16  which can be screwed onto the shank  10  by means of a screwthread  18 , a spindle  20 , a first pawl mechanism  22 , a second pawl mechanism  24 , a first coil spring  26 , a sharpener  28  and a second coil spring  30 . 
     The pencil shown in  FIG. 1  functions as follows: 
       FIG. 1  ( a ) shows the pencil with a blunt lead  14 . To sharpen the lead the protective cap  16  is screwed onto the shank  10 , as shown in  FIG. 1  ( b ). The screwthread  18  serves for that purpose. When the protective cap  16  is further screwed onto the shank  10  from the operating position shown in  FIG. 1  ( b ), after a certain amount of screwing movement it bears against an axial abutment  32  on the cartridge  12  and pushes the cartridge  12  into the shank  10  until the abutment  32  bears against the cartridge  10 . As a result the cartridge is displaced by the extent M which in the illustrated embodiment is 0.8 mm. 
     Because of the pawl mechanism  22  which engages into the spindle  20  neither the spindle  20  nor the lead  14  is displaced with the cartridge  12 . Rather, the spindle  20  pushes the lead  14  out of the cartridge  12 , more specifically by the amount M. 
     As the sharpener  28  moves together with the protective cap  16 , that is to say on the one hand is rotated and on the other hand is displaced towards the left in the drawing, the lead  14  is sharpened. To prevent the sharpener  28  exerting excessive pressure on the lead  14 , it is supported by way of the coil spring  30 . It can accordingly deflect towards the right in the drawing. 
     As shown in the drawing the mere fact of screwing the protective cap  16  onto the shank  10  into the position shown in  FIG. 1  ( c ) suffices to sharpen the lead  14 . 
     When now the protective cap  16  is unscrewed from the shank  10  again, the spring  26 , by way of the pawl mechanism  24 , urges the spindle  20 , the lead  14  and the cartridge  12  out of the shank  10  again so that the operating condition shown in  FIG. 1  ( a ) is restored, but with the difference that the lead  14  has been sharpened and is extended out of the cartridge  12  by the distance M. 
     The embodiment shown in  FIG. 2  substantially corresponds to that shown in  FIG. 1  but with the difference that, instead of the sharpener  28 , the arrangement has a guide template  34  and a flexible blade  36 . In addition there is no screwthread for screwing the protective cap  16  onto the shank  10 . Rather the protective cap  16  can be pushed onto the shank  10 . 
     The  FIG. 2  embodiment functions as follows: 
       FIG. 2  ( a ) once again shows the pencil with the blunt lead  14 . When the protective cap  16  is pushed onto the shank  10  the guide template  34  bears against the abutment  32 . That condition is shown in  FIG. 2  ( b ). When the protective cap  16  is further pushed onto the shank  10 , that provides that the guide template  34  pushes the cartridge  12  into the shank  10 , by way of the abutment  32 . In comparison the spindle  20  and the lead  14  are not displaced because of the pawl mechanism  22 . Rather, the coil spring  26  is stressed. 
     When the abutment  32  bears against the shank  10  the protective cap  16  is displaced towards the left in the drawing with respect to the guide template  34 . As a result the blade  36  slides transversely over the guide template, through which the lead  14  extends by virtue of the displacement thereof. As a result the lead  14  is cut off inclinedly. In that situation the guide template  34  bears against a coil spring  38  which is correspondingly stressed. That provides that the lead  14  is re-shaped again at its working end. 
     When thereafter the protective cap  16  is withdrawn from the shank  10  again, the pencil assumes the condition shown in  FIG. 2  ( d ). For that purpose the coil spring  26  urges the pawl mechanism  24  and therewith the spindle  20  and the lead  14  out of the cartridge  12  by the distance M so that the condition shown in  FIG. 2  ( a ) is restored, except that the lead  14  is no longer blunt. 
     Accordingly, the embodiment of  FIG. 2  also provides that merely pushing the protective cap  16  onto the shank  10  is sufficient to suitably shape the lead  14  at its working end. 
     The embodiment of  FIG. 3  functions as follows: 
       FIG. 3  ( a ) again shows the pencil with a blunt lead  14 . When the protective cap  16  is pushed onto the shank it bears against the abutment  32 . That condition is shown in  FIG. 3  ( b ). Further pushing movement of the protective cap  16  onto the shank  10  provides that the cartridge  12  is pushed into the shank  10  by means of the abutment  32 . In comparison the spindle  20  and the lead  14  are not displaced because of the pawl mechanism  22 . The coil spring  26  is stressed. 
     The protective cap  16  can be pushed onto the shank until the abutment  32  bears against the shank  10 . That condition is shown in  FIG. 3  ( c ). The view in  FIG. 3  ( c ) also differs from that shown in  FIG. 3  ( b ) however in that a knob  40  is depressed. Depressing the knob  40  causes the blade  36  to cut off the lead  14  by virtue of the blade traveling along the guide template  34 . In that case a coil spring  42  is stressed, which moves the blade  36  into its starting position again when the knob  40  is released. 
     When the protective cap  16  is withdrawn from the shank  10  again after the lead  14  has been cut off, the pencil assumes the condition shown in  FIG. 3  ( d ). For that purpose the coil spring  26  urges the pawl mechanism  24  and therewith the spindle  20  and the lead  14  out of the cartridge  12  by the extent M so that the condition shown in  FIG. 3  ( a ) is restored, except that the lead  14  is no longer blunt. 
     As the foregoing description shows, in the embodiment of  FIG. 3  the mere fact of pushing the protective cap  16  onto the shank  10  is also sufficient to displace the lead  14  axially within the cartridge  12  for shaping purposes. 
     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. 
     Points of explanation in relation to  FIG. 1 : 
     a) blunt lead 
     b) cartridge is pushed back 
     c) sharpening of the lead 
     d) sharp lead ready for makeup

Technology Classification (CPC): 1