Patent Publication Number: US-8993910-B2

Title: Group of momentary-contact switches as control panel which can be illuminated in motor vehicles

Description:
RELATED APPLICATIONS 
     This application corresponds to PCT/EP2010/004237, filed Jul. 12, 2010, which claims the benefit of German Application No. 10 2009 036 209.6, filed Aug. 5, 2009, the subject matter, of which we incorporated herein by reference in their entirety. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a pushbutton switch array which is specially suited for use as an operating panel in a motor vehicle. 
     Switch arrays which are built into a faceplate or a frame and are composed of illuminatable switch units are known. Each switch unit has its own source of illumination. It is also known to use an optical waveguide structure to illuminate a plurality of switch units, the optical waveguide structure distributing the light from a shared light source or few shared light sources to a plurality of switch units. Both solutions are relatively complicated. 
     SUMMARY OF THE INVENTION 
     The invention provides a pushbutton switch array having illuminatable switch units which manages with one light source or only few light sources and does not require a separate optical waveguide structure for distributing the light to the various switch units. 
     The pushbutton switch array according to the invention has a frame which is covered by a transparent film and includes recesses which each have an actuating element accommodated therein for displacement. The actuating elements are configured to have light-guiding and light-coupling structures. A shared light source is, or only few shared light sources are, optically coupled to the light-coupling structures of the actuating elements which, for their part, are optically coupled to each other by adjoining light-coupling structures. The light-guiding structures guide the light coupled into the actuating elements to the actuating surface adjacent to the film. The actuating elements may be provided with symbols on their actuating surface adjoining the film, the symbols being visible through the film. Preferably, however, it is the film itself which is provided with symbols and/or legends which are assigned to the actuating elements arranged therebehind. These symbols are then illuminated by the actuating elements. If the frame also consists of a light-transmissive material, e.g., a plate made from a polycarbonate, the symbols/legends may, if required, be extended laterally beyond the actuating surface located therebehind, so that larger symbols/legends may also be used. 
     A shared printed circuit board preferably closes the pushbutton switch array on the rear side facing away from the film. Arranged on this printed circuit board are the light sources and assigned switch elements located in opposition to the end faces of the actuating elements facing away from the film. 
     Advantageous further developments of the invention are specified in the dependent claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages and features of the invention will become apparent from the description below given with reference to the accompanying drawings, in which:
           FIG. 1  shows a top view of a pushbutton switch array;     FIG. 2  shows the pushbutton switch array in a schematic sectional view;     FIG. 3   a  shows a side view of an actuating element; and     FIG. 3   b  shows a top view of an actuating element.       

     
    
    
     DESCRIPTION OF AN EXEMPLARY EMBODIMENT 
       FIG. 1  shows a smooth operating panel  10  which is formed by a transparent film  12  ( FIG. 2 ). Four symbols  14 ,  16 ,  18 ,  20  shown by way of example as well as a legend  22  are visible through the film or on the film itself. Round recesses  24 ,  26 ,  28 ,  30 ,  32  formed in a frame  34  ( FIG. 2 ) under the film are indicated in dashed lines. The frame  34  is formed by a plastic plate made from a transparent material such as a polycarbonate plastic. The recesses  24  to  32  constitute sliding guides for actuating elements  36 ,  38 ,  40 ,  42  and  44  inserted therein which are in the shape of small blocks and consist of a transparent material such as a polycarbonate plastic. 
     A printed circuit board  50  closes the pushbutton switch array on the rear side facing away from the film  12 . In the embodiment shown, the printed circuit board  50  is equipped with two light sources  52 ,  54  in the form of light-emitting diodes (LEDs) and with switch elements  56 ,  58 ,  60 ,  62 ,  64 , which correspond to the actuating elements  36  to  44 . 
     Depending on the ergonomic demands on the operating panel realized with the pushbutton switch array, the actuating elements may be all of the same design or of different designs. 
       FIGS. 3   a  and  3   b  schematically show an exemplary embodiment of such an actuating element. The actuating element is a solid body made from a transparent material such as a polycarbonate plastic and consists of a cuboid base body  70  and a cylindrical guide body  72  placed thereon in the middle. Owing to its solid construction from a material having an index of refraction that is greater than that of air, the actuating element as a whole constitutes an optical waveguide. This optical waveguide has optical surfaces laterally on the cuboid base body  70  for coupling light in and out and guides light coupled in into the cylindrical guide body  72 ; proceeding from there, it shines through the film  12 . In the configuration shown in  FIG. 2 , the two light sources  52  and  54  radiate into the lateral coupling-in surfaces of the outer actuating elements  36  and  44 . The light from both light sources is coupled into all of the actuating elements via the lateral, closely adjacent optical surfaces for coupling light in and out and is available to illuminate the respectively associated symbols or legends. 
     In the embodiment shown, the legend  22 , “SPORT”, has an extent that goes laterally beyond the boundaries of the recess  28 . Nonetheless, this legend is fully illuminated because at the outer edges thereof the shoulder located therebehind of the actuating element base body  70  couples the light into the transparent frame  34 .