Abstract:
The present invention relates to a navigational button including an actuating element which is displaceable at least in two directions and controls the navigation button. The present actuating element is arranged in a casing and performs an action on a communication element. A limitation element is disposed between the actuating element and the casing in such a way that it limits actuation efforts performed on the navigational button.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   The present application is a continuation of International Application Serial Number PCT/DE03/03120, filed Sep. 19, 2003, which designated the United States and further claims priority to German patent application 10247093.6, filed Sep. 10, 2002, the both of which are herein incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   The invention relates to a navigation switch having an operating element which can be tilted in at least two directions and which can be used to operate the navigation switch, a housing holding the operating element and a switching element on which the operating element acts. 
   Navigation switches normally have a switching housing with a switching element arranged in the interior of the switching housing, said switching element being able to be moved against at least two contact regions and, when moved, reaching a contact position which switches an electrical contact. The switching element has an operating arm routed to the exterior as an axial extension to a switching lever arranged in the interior of the housing. The operating arm can be pivoted in a plurality of directions from a central position of rest using a control element which is located in a switching housing. 
   Such navigation switches are known for diverse applications. They are generally used to control electronic appliances in consumer electronics, such as in digital cameras, video recorders or mobile telephones or else for menu control in electronic data processing appliances. In particular, they are used for reducing the components when individual components are assigned a plurality of functions. 
   To operate the switching element, the operating element has a tappet situated on its underside so that it is possible to make mechanical contact with the operating arm of the switching element. When the operating element is operated, the tappet on the operating element transfers the operating force to the operating arm of the switching element, so that the latter reaches a contact position and switches an electrical contact. 
   The navigation switches described in the outset have no protection against excessive operating forces at the present time. Improper or excessively heavy operation of the operating element produces a large operating force on the operating arm of the switching element which can result in destruction of the switching element. In addition, an undefined tilting movement of the operating element can result in destruction of the switching element. 
   SUMMARY OF THE INVENTION 
   It is an object of the invention to provide a navigation switch in which the switching element has better protection against premature wear and destruction. 
   The invention achieves the object by virtue of the operating element and the housing having a limiting element arranged between them which limits the operating forces on the switching element. 
   This navigation switch has the advantage that the use of a limiting element between the operating element and the housing which holds the operating element allows any type of switching elements to be protected against improper or excessively heavy operation. 
   The fact that the limiting element has a centrally provided cutout which corresponds to the dimensions of a tappet on the operating element allows the operating element to be guided in tracks and therefore prevents undefined tilting. 
   Excessively large operating forces are routed into the side walls of the housing which holds the limiting element by way of the limiting element. The tappet on the operating element can be securely guided on the operating arm of the switching element. 
   In one advantageous development, the limiting element is in the form of an integral part of the housing, and the limiting element and the housing are made of an elastomeric plastic. 
   In addition, one advantageous refinement provides for the limiting element to be convex relative to the operating element and to have a latticed structure. 
   Similarly, the limiting element may also be in the form of a curved plate made of plastic or metal. 
   In this context, it is beneficial for the limiting element to have an axial cutout for holding a tappet located on the underside of the operating element. 
   In one preferred form of the invention, the housing holding the limiting element encloses a circular cavity, with the outer region of the base which limits the cavity containing at least two latches, and the convex limiting element has at least two further mating latches which engage in the matching latches on the housing. 
   In this context, the limiting element is inserted into the cavity in the housing, and following assembly the limiting element is rotated clockwise through 45 degrees in order to latch it, so that the mating latches on the limiting element engage in the latches on the housing. 
   The invention makes it possible to employ very little production and assembly complexity to provide a navigation switch in which wear occurring under normal circumstances on account of excessively great operating forces is prevented by means of a limiting element. The modular unit of the housing for holding the operating element can be mounted and handled in preassembled form, without the need to use particular care. 
   Large operating forces arising on the operating element are routed into the side walls of the housing by means of the additional limiting element. The use of limiting elements allows microswitches, too, to be protected against improper or excessively heavy operation. At the same time, the limiting element allows the operating element to be guided in tracks in order to prevent undefined tilting. 
   The use of the optionally useable limiting element allows the properties to be aligned regardless of the material of the housing. The useful life of the navigation switch or of the switching element is influenced positively. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The invention is explained in more detail below using exemplary embodiments which are shown in the figures. Elements which are identical or which correspond to one another in different figures are provided with the same reference symbols. 
     In the figures: 
       FIG. 1  shows a perspective exploded illustration of a navigation switch based on the invention, 
       FIG. 2  shows the plan view of the navigation switch shown in  FIG. 1 , 
       FIG. 3  shows a vertical section D-D from  FIG. 2 , 
       FIG. 4  shows a perspective illustration from obliquely above of a housing (holding the operating element) with an integrated limiting element, 
       FIG. 5  shows the plan view of the housing shown in  FIG. 4 , 
       FIG. 6  shows the horizontal section A-A through the housing shown in  FIG. 5 , 
       FIG. 7  shows the vertical section B-B through the housing shown in  FIG. 5 , 
       FIG. 8  shows a perspective exploded illustration of a further navigation switch based on the invention, 
       FIG. 9  shows the plan view of the navigation switch shown in  FIG. 8 , 
       FIG. 10  shows the vertical section C-C through the navigation switch shown in  FIG. 9 , 
       FIG. 11  shows a perspective illustration from obliquely above of the housing which holds the operating element, 
       FIG. 12  shows a plan view of the housing shown in  FIG. 11 , 
       FIG. 13  shows the vertical section A-A through the housing shown in  FIG. 12 , 
       FIG. 14  shows a diagonal section B-B through the housing shown in  FIG. 12 , 
       FIG. 15  shows the plan view of the limiting element of the inventive navigation switch shown in  FIG. 8 , 
       FIG. 16  shows the section A-A from  FIG. 15 , and 
       FIG. 17  shows a side view of the limiting element shown in  FIG. 15 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows the perspective illustration of a navigation switch based on the invention. The navigation switch has a switching element  3  with a square base area, said switching element being arranged on a housing part or on a board  4 , for example. The switching element  3  has an operating arm  32  which is routed through a cutout in the cover of the switching element  3  and which serves as an axial extension to a switching lever (not shown here) arranged in the interior of the switching element  3 . The switching lever arranged centrally in the interior of the switching element  3  can be moved against at least two contact regions, so that upon movement into a contact position an electrical contact is switched. 
   In addition, the navigation switch has a circular operating element  1  having four radially and one centrally arranged switching positions. The underside of the operating element  1  carries a tappet  11  arranged in the axial direction. In addition, the navigation switch has a housing  2  with a circular cavity  21  which corresponds to the dimensions of the operating element  1 . In the assembled state, the operating element  1  is held by the housing  2 , and the housing  2  is arranged above the switching element  3 , so that the tappet  11  on the operating element  1  engages centrically in the operating arm  31  of the switching element  3 . 
   The switching element  3  is operated by means of the operating element  1 , with the tappet  11  on the operating element  1  transferring the operating forces to the operating arm  31  of the switching element  3 , so that the operating arm  31  is moved into a switching position. In this context, a limiting element  5  arranged in the housing  2  limits the forces acting on the operating arm  31  of the switching element  3 . 
     FIG. 2  shows the plan view of the navigation switch described in  FIG. 1  with the operating element  1  arranged centrally in the housing  2 . 
   The section D-D from  FIG. 2  is shown in  FIG. 3 . As already discussed previously, the operating element  1  can be found in the housing  2 , with the tappet  11  on the operating element  1  engaging around the operating arm  31  of the switching element  3 . In the base region within the cavity  21  in the housing  2 , there is an integrally molded limiting element  5  arranged convexly relative to the operating element  1 . 
   As can be seen in detail from the perspective illustration of the limiting element  5  in  FIG. 4  and from the plan view of the housing  2  with an integrated limiting element  5  in  FIG. 6 , the limiting element  5  has a central cutout  53  which corresponds to the external dimensions of the tappet  11  on the control element  1 . It can also be seen that the limiting element  5  has a latticed structure, with the limiting element  5  in the advantageous refinement shown in  FIG. 5  having spurs  52  which oppose one another in pairs parallel to the lateral and longitudinal axes of the limiting element  5  starting from the square collar  51  provided centrally with the cutout, the end of said spurs being integrally molded on the housing. 
   In this embodiment shown, the limiting element  5  is preferably made from an elastomeric plastic, for example, as an integral part of the housing  2 . 
     FIGS. 6 and 7  respectively show the horizontal section A-A and the vertical section B-B from  FIG. 5 . The convexly curved limiting element is molded to the housing in a manufacturing process. 
     FIG. 8  shows a further advantageous refinement of the inventive navigation switch. In this case, a separate limiting element  6  is provided which is inserted into the base of a housing  7 . 
     FIG. 9  shows the plan view of the navigation switch described in  FIG. 8  with the operating element  1  arranged centrally in the housing  7 . 
     FIGS. 11 to 14  show various perspective views of the housing  7  holding the operating element  1 . The housing  7  encloses a circular cavity  71  and has, on its base, as can be seen in detail from  FIGS. 11 to 14 , four latches  72  arranged radially on the side walls of the cavity  71 . 
     FIGS. 15 to 17  show an embodiment of the limiting element  6 . The limiting element  6  is in the form of a convexly curved plate with four mating latches  61  which are arranged at a lateral edge  62  and which are arranged radially at the same distance. 
   The limiting element  6  has a central cutout  63  which corresponds to the dimensions of the tappet  11  on the operating element  1 . The tappet  11  on the operating element  1  runs through this cutout, so that secure guidance of the tappet  11  is made possible and hence uncontrolled operation of the operating arm  31  is prevented. 
   For the purposes of latching, the operating element  6  is rotated clockwise through 45 degrees and is thus firmly connected to the housing  7 . 
   The particular mode of action of the limiting elements  5  and  6  can be seen from the sectional illustrations in  FIGS. 3 and 10 . 
   In the assembled state, the underside of the operating element  1  is at a minimum distance d from the top  54 ,  64  (see  FIG. 3  and  FIG. 10 ) of the limiting elements  5 ,  6  located in the housing  2 ,  7 . A force f can be introduced onto the operating element  1  centrically or eccentrically. As can be seen from  FIG. 10 , in particular, the result of centric introduction of force f is that the control element  1  displaces the operating arm  31  of the switching element  3  downward into the switching element  3  through the path e. The path e represents a movement limitation provided by the limiting elements  5  and  6 . In addition, the operating elements  5  and  6  limit tilting when a force is introduced eccentrically, on account of the distance d of the operating element  1  from the top  54 ,  64  of the limiting element  5 ,  6 . In the event of excessive centric or eccentric introduction of force f, the compressive force on the operating element  1  is dissipated into the walls of the housing  2  and  7 .