Patent Publication Number: US-2022229465-A1

Title: Display device for a vehicle

Description:
The present patent application claims the priority of the national German Patent Application 10 2019 114 357.8 of May 28, 2019, the disclosure of which is incorporated into the present application by reference. 
     The invention relates to a display device for a vehicle which, in addition to the display of information, may, it so desired, serve for the manual input of commands, for which purpose the display device may be designed as a touch screen, for example. 
     Display devices comprising displays are increasingly mounted in vehicles. For example, they may be used as so-called CID (Central Input Devices) and are then also provided with a command input function. In these cases, these are mostly touch screens which may have a variety of graphical surfaces. 
     Recently, self-supporting display devices arranged at and/or on the instrument panels have found their way into the automotive domain. These display devices comprise a stable rear wall serving to hold the display of the display device. The self-supporting display devices are arranged on the instrument panel either rigidly or movably so that they can be automatically moved to a rest or retracted position when not in use. 
     For reasons of stability, the rear walls or rear housing shells of the above-mentioned display devices comprise metal or cast metal. 
     In prior art, the displays are fixed to the housing shell or rear walls by means of adhesive tapes, with the rear side of the display resting flat against the housing shell or the rear wall thereof. Here, it is necessary that the rear wall is planar. The TFT displays mainly used today are rather sensitive to mechanical stresses and show optical abnormalities when fixedly adhered on uneven surfaces. 
     DE-A-197 22 682 describes a display device for buses that is arranged behind a side, front or rear window of a bus. The display device comprises a display held by a fastening means. The fastening means is open at the front side which faces the relevant window of the bus in the installed state of the display device, so that the display surface of the display is visible from outside through the relevant bus window. The fastening means may be removably fastened on the relevant window, with the display surface of the display being spaced from bus window. 
     DE-A-10 2014 019 324 describes a display device comprising a display for installation in a vehicle, the display device including a decorative frame surrounding the display. 
     It is an object of the present invention to provide a display device, the display of which is mounted with sufficient stability and strength on a rear housing shell, without requiring a two-dimensional bonding of the display and the housing shell. 
     To achieve this object, the invention proposes a display device for a vehicle, which is provided with:
         a display with a display surface on a front side and with a rear side opposite thereto,   a cover screen arranged in front of the display surface,   a decorative frame which is connected to the edge of the cover screen and protrudes on all sides over the edge of the display, and   a rear housing shell which has a rear wall with an edge web protruding from the latter,   the rear wall of the housing shell being arranged at a distance from the rear side of the display and   the edge web of the housing shell is connected to the decorative frame by means of an adhesive.       

     According to the concept of the invention, the connection of the rear housing shell and the rear wall of the display device is made by bonding the edge of the housing shell to the decorative frame of the display device. The decorative frame of the display device itself is a part of the cover screen which is also referred to as “cover glass”. To this end, the rear wall of the display device is designed as a housing shell with a protruding edge web that is designed to be circumferential. Thus, the edge web protrudes from the rear wall (i.e. the bottom wall of the housing shell) and surrounds the display on all sides. The free end of the edge web is connected to the decorative frame by means of the adhesive, which frame surrounds the cover screen on all sides. In the connected state of the housing shell and the decorative frame, the rear of the display is spaced from the rear wall of the housing shell; thus, an air gap exists between both. Accordingly, the display is no longer in contact with the rear and is in particular no longer two-dimensionally bonded to the rear. As is common, the display is fastened or mounted to the cover screen by means of a transparent adhesive (optical bonding) and thus “hangs” from the same. In view of the vibrations occurring in a vehicle while driving, this connection of the display and the cover screen is stable. Mechanical stresses between the display and the cover screen cannot occur, since both the display surface of the display and the cover screen are basically planar. If it is intended to use curved cover screens, the difference between the curved cover screen and the planar display surface of the display is compensated for by the transparent adhesive and, meanwhile, there are displays with curved display surfaces, with the cover screens being designed to match the shape thereof, whereby both can again be bonded with a constant distance therebetween. In all these variants, a touch panel may also be provided as a touch sensor system that operates optically, capacitively, inductively or resistively. 
     As already mentioned above, the invention is particularly suitable for display devices that are arranged self-supported. To this end, the housing shell has a mounting part, which is typically formed to be integral, for mounting the housing shell in a vehicle for a self-supporting arrangement of the display device at and/or on and/or in the vehicle instrument panel. As an alternative, it is also possible that the housing shell is coupled with an extension and retraction mechanism by which the display device can automatically extended and retracted. 
     In a further suitable embodiment of the invention it is provided that the adhesive connecting the edge web of the housing shell to the decorative frame on the cover screen of the display is designed as a strip-shaped adhesive material bed on the decorative frame, into which the edge web of the housing shell is immersed at its end averted from the rear wall of the housing shell. The strip-shaped adhesive material bed is sometimes also referred to as an “adhesive bead”. 
     With regard to the possibility of tolerance compensation, it is advantageous if the edge web of the housing shell is immersed into the adhesive material bed at its end averted from the rear wall of the housing shell while maintaining a distance from the decorative frame—as viewed in extension of the edge web. 
     In a further suitable embodiment of the invention it is provided that the decorative frame comprises a connecting section extending circumferentially around the cover screen and having an adhesive application surface for the adhesive connecting the edge web of the housing shell to the decorative frame on the cover screen of the display. As already mentioned above, the decorative frame is itself fastened to the cover screen and is formed along the circumference thereof. The decorative frame is provided with an adhesive application surface which is located in a connecting section of the decorative frame which serves to connect to the edge web of the housing shell, possibly with the interposition of the strip- or strand-shaped adhesive material bed. The edge web may rest on the decorative frame or may also be arranged at a distance from the connecting section of the edge web by being partially immersed into the adhesive material bed. 
     Typically, the display is connected to the cover screen by means of a transparent adhesive layer and/or the display comprises a touch panel or a touch sensor system that operates optically, capacitively, inductively or resistively. Usually, the touch panel is connected to the cover screen and/or the display surface of a display by means of an optically transparent adhesive, but may also be an integral part of the display. 
     Typically, displays are provided with a backlighting unit with which the display surface of the display can be backlit. Such a backlighting unit is located rearward of the display surface of the display. Usually, a diffusor for homogenizing the backlighting of the display surface is located between the backlighting unit and the electronic components. The backlighting unit forms the rear of the display. 
    
    
     
       The invention will be explained hereinafter with reference to an embodiment and to the drawings. In detail, the Figures show: 
         FIG. 1  a view of the instrument panel of a vehicle with a display device arranged standing upright on the instrument panel, and 
         FIG. 2  a section through the display device along II-II in  FIG. 1  to clarify the structure of the display device. 
     
    
    
       FIG. 1  illustrates a view of the instrument panel  10  in the interior of a vehicle. A self-supporting display device  12 , which in the present embodiment is designed as a touch screen, is situated on the instrument panel  10 . At the front, the display device  12  has a cover screen  14  with a circumferential frame  16 . Rearward of the cover screen  14 , a housing shell  17  is located which closes the display device  12  to the rear and comprises a mounting part  19  for self-supported mounting on the instrument panel  10  (see  FIG. 2 ). 
     The actual display  18  with the display surface  20  is situated behind the cover screen  14 . Between the cover screen  14  and the display  18 , typically a touch panel  22  is located which is connected to the cover screen  14  by means of a transparent adhesive (not illustrated) and to which the display surface  20  of the display  18  is bonded by means of a transparent adhesive layer  24  (optical bonding). Usually, a backlighting unit  26  with a diffusor (not illustrated) is located behind the display  18 . 
     The decorative frame  16  is connected to the cover screen  14  e.g. by adhesion, the adhesive being illustrated at  28 . The decorative frame  16  may, however, also be integrally formed as a single piece with the cover screen  14 . For example, the decorative screen  16  has an inward protruding connecting section  30  as a kind of inner flange on which the cover screen  14  rests bonded by means of the adhesive  28 . On the lower side of the connecting section  30  averted from the adhesive, an adhesive application surface  32  is provided on which a strand- or strip-shaped adhesive material bed  34  is applied. 
     The housing shell  17  has a rear wall  36  and a circumferential edge web  38  protruding therefrom, the free end  40  thereof being immersed into the adhesive material bed  34 , namely, in this embodiment, with a distance to the adhesive application surface  32  of the connecting section  30  of the decorative frame  16 . 
     In the bonded state of the housing shell  17  and the decorative frame  16 , the rear  40  of the display  18  is spaced from the rear wall  36  of the housing shell  17 . 
     For mounting the display device  12 , the housing shell  17  is set, for example, on the display  18  pre-assembled to the cover screen  14  with the decorative frame  16 . At this point, the display  18  is connected to the cover screen  14 . The decorative frame  16  of the cover screen or of the display device  12  is also already provided on the cover screen  14 . Using a positioning device, the housing shell  17  is then slipped over the display  18  from behind in such a manner that the free end  40  of the edge web  38  is pressed into the not yet cured adhesive material bed  34 . Here, care is taken to keep the rear wall  36  of the housing shell  17  spaced from the rear  42  of the display  18 . Due to the fact that the edge web  38  and the connecting section  30  of the decorative frame  16  are not in contact, possible manufacturing tolerances of the two partial components connected according to the above described method can be compensated for. Moreover, it is possible to adjust the design gap between the decorative frame  16  and the housing shell  17  accordingly. 
     LIST OF REFERENCE NUMERALS 
     
         
           10  instrument panel 
           12  display device 
           14  cover screen 
           16  decorative frame 
           17  housing shell 
           18  display 
           19  mounting part 
           20  display surface 
           22  touch panel 
           24  transparent adhesive layer 
           26  backlighting unit 
           28  adhesive 
           30  connecting section of the decorative frame 
           32  adhesive application surface 
           34  adhesive material bed 
           36  rear wall of the housing shell 
           38  edge web 
           40  end of the edge web 
           42  rear of the display