Abstract:
A control device for a vehicle includes a transparent support, an opaque decorative layer, a detection layer, and a light source adapted for emitting a light passing through the transparent support. The opaque decorative layer is printed on the transparent support in a control area, and delimits a pattern forming a pictogram where the decorative layer is missing, with the pictogram having an outer edge. The detection layer is electrically conductive and printed on the transparent support around the pictogram, substantially up to the outer edge of the pictogram, in the control area.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to a control device, in particular for a vehicle, and a method for producing such control device. 
       BACKGROUND OF THE INVENTION 
       [0002]    Such control device is sometimes named control switch. More particularly, the invention relates to a so-called backlit control device, specifically in order to allow locating the control device in the dark and/or informing a user about the state of the appliance which the control device allows controlling. 
         [0003]    Such device is usually arranged in the passenger compartment, in particular, on a dashboard, a central console, a door panel, or an overhead light. 
       SUMMARY 
       [0004]    An object of the invention is to provide a control device which may easily be produced, at an efficient cost, providing a good aesthetic quality while ensuring relying detection. 
         [0005]    To this, in accordance with an aspect of the invention, the control device comprises: 
         [0006]    a transparent support, 
         [0007]    an opaque decorative layer, printed on the transparent support in a control area, the decorative layer delimiting a pattern forming a pictogram where the decorative layer is missing, said pictogram having an outer edge, 
         [0008]    a detection layer, which is electrically conductive and printed on the transparent support around the pattern forming the pictogram in the control area, said detection layer having an inner edge, and 
         [0009]    a light source adapted for emitting a light passing through the transparent support within the pattern forming the pictogram, 
         [0010]    wherein the detection layer extends substantially up to the outer edge of the pictogram. 
         [0011]    Thus, the decorative layer delimits the pictogram illuminated by the light source and masks the detection layer, while the detection layer allows good detection of the presence of a user finger facing the pictogram, extending substantially all around the pictogram. 
         [0012]    The inner edge of the detection layer may have a noncircular shape that corresponds substantially to the shape of the outer edge of the pictogram. 
         [0013]    Thus, detection layer forming a large diameter ring, very easy to produce but risking bad detection of the presence of a user finger when the user has a slim finger, is avoided. 
         [0014]    The inner edge may be in the immediate proximity of the outer edge of the pictogram on at least the majority of the outer edge of the pictogram. 
         [0015]    It should be understood by “immediate proximity” in particular being distant from 1 mm or less, and by “majority” more than half of the outer edge pictogram. Thus, detection quality is improved. 
         [0016]    The inner edge of the detection layer may coincide with the outer edge of the pictogram on at least the majority of the outer edge of the pictogram. 
         [0017]    Thus, detection is optimized in particular when allowed by the production method without risking showing the inner edge of the detection layer. 
         [0018]    In various embodiments of the device, one and/or another of the following arrangements may potentially further be used: 
         [0019]    the transparent support is formed by a film having a thickness of less than one millimeter, preferably less than 0.5 mm; 
         [0020]    the support is made of polycarbonate (PC) or polyethylene terephthalate (PET); 
         [0021]    the detection layer extends all around the pictogram; 
         [0022]    the control device comprises a capacitive sensor, said capacitive sensor including said detection layer; 
         [0023]    said detection layer is made of copper and/or silver; 
         [0024]    the decorative layer is between the transparent support and the detection layer; 
         [0025]    the control device further comprises a protective layer covering the detection layer and the decorative layer. 
         [0026]    The invention also relates to a casing member comprising a rigid support molded on the control device. 
         [0027]    The invention further relates to a method for producing a control device wherein the following steps are performed: 
         [0028]    a) arranging a transparent support having a top surface and a bottom surface, 
         [0029]    b) in the control area, printing with an opaque ink on the bottom surface of the transparent support to form an opaque decorative layer, the decorative layer delimiting a pattern forming a pictogram where the decorative layer is missing, said pictogram having an outer edge, 
         [0030]    c) in the control area, printing with an electrically conductive ink on the transparent support substantially up to the outer edge of the pictogram, 
         [0031]    d) arranging a light source in the control area, facing the bottom surface of the transparent support. 
         [0032]    Thus, the production is relatively simple and inexpensive, while providing a good detection quality and a good appearance. 
         [0033]    In various embodiments of the method according to the invention, one and/or another of the following arrangements may potentially further be used: 
         [0034]    step c) is performed after step c) and during step c) the electrically conductive ink is printed on the opaque ink; 
         [0035]    printing is performed at steps b) and c) by screen printing; 
         [0036]    a mask is used for producing the pictogram at step b) and said mask is used at step c); 
         [0037]    the method further comprises a step during which the transparent support is arranged in a molding cavity, and then the molding cavity is filled with plastic material in order to mold a rigid support on the bottom surface of the transparent support. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0038]    Other features and advantages of the present invention will appear in the following detailed description, referring to the accompanying drawings wherein: 
           [0039]      FIG. 1  represents a control device in compliance with the invention, 
           [0040]      FIG. 2  represents a control device viewed in section along the II-II line located in  FIG. 1 , 
           [0041]      FIG. 3  represents a first step of a method in compliance with the invention for producing the control device, 
           [0042]      FIG. 4  represents a second step of a method in compliance with the invention for producing the control device, 
           [0043]      FIG. 5  represents a third step of a method in compliance with the invention for producing the control device, 
           [0044]      FIG. 6  is a scaled up view of the area VI located in  FIG. 5 , 
           [0045]      FIG. 7  represents a fourth step of the method in compliance with the invention for producing the control device. 
           [0046]      FIG. 8  represents a fifth step of the method in compliance with the invention for producing the control device. 
       
    
    
     DETAILED DESCRIPTION 
       [0047]      FIGS. 1 and 2  represents a casing member  110  arranged in the passenger compartment  100 . In the represented embodiment, the casing member  110  constitutes a dashboard and more precisely a central console. 
         [0048]    The casing member  110  comprises a rigid support of  30  molded on a control device  1 . The control device  1  has three control areas  2 ,  4 ,  6  each comprising a pictogram  10  having an outer edge  10   a.    
         [0049]    The control device  1  comprises mainly a transparent support  12 , a decorative support  14 , a capacitive sensor  20  including a detection layer  16 , as well as a light source  18  for lighting the pictogram of each of the control areas  2 ,  4 ,  6 . 
         [0050]    The transparent support  12  has a top surface  12   a  and a bottom surface  12   b.  In the represented embodiment, the transparent support  12  is flexible and formed by a film having a substantially constant thickness, preferably smaller than 1 mm, preferably substantially equal to 0.3 mm. The transparent support  12  is preferably made of polycarbonate (PC) or polyethylene terephthalate (PET). 
         [0051]    The decorative layer  14  is opaque and electrically insulating. It has a substantially constant thickness and is arranged on the bottom surface  12   b  of the transparent support  12 . Optionally, one or more translucent layers may be interposed between the transparent support  12  and the decorative layer  14 , in order to improve the aesthetic appearance of the control device  1 , having a top surface  12   a  of the support  12  constituting the visible portion. 
         [0052]    The decorative layer  14  delimits a pattern forming a pictogram  10 . That is, the lack of decorative layer  14  defines the pictogram  10 . The outer edge  10   a  of each of the pictograms  10  therefore constitutes a rim of the decorative layer  14 . In the represented embodiment, each of the pictograms  10  is entirely surrounded by the decorative layer  14 , so that the pictograms  10  are apart from the periphery of the control device  1 . It will be noted that based on the pattern of the pictogram  10 , the decorative layer  14  may or not be present inside the area delimited by the outer edge  10   a  of the pictogram. Thus, in the control area  2 , the decorative layer  14  is not present inside the area delimited by the inner edge  10   a  of the pictogram  10 , while in the control areas  4 ,  6 , the decorative layer  14  comprises a first portion located outside the inner edge  10   a  of the pictogram  10  and a second portion located inside the inner edge  10   a  of the pictogram  10 , said first portion and second portion of the decorative layer  14  being separate. 
         [0053]    The detection layer  16  is electrically current-conductive and entirely arranged on the decorative layer  14 . The detection layer  16  extends forming a strip delimited by an inner edge  16   a  and an outer edge  16   b  and which is closed on itself around the pictogram  10  of each of the other control areas  2 ,  4 ,  6  in the represented embodiment. The decorative layer  14  is interposed between the detection layer  16  and the transparent support  12 , so that the detection layer is not visible to a user on the top surface  12   a  side. 
         [0054]    The inner edge  16   a  of the detection layer  16  may be slightly recessed relative to the outer edge  10   a  of the pictogram  10 . However, advantageously and in the represented embodiment, the inner edge  16   a  of the detection layer  16  corresponds to the outer edge  10   a  of the pictogram  10  for each control area  2 ,  4 ,  6 . Thus, the outer edge  10   a  of the pictogram  10  having a noncircular shape, the inner edge  16   a  of the detection layer  16  has the same shape. Nevertheless, the outer edge  16   b  of the detection layer  16  is preferably substantially circular. 
         [0055]    The capacitive sensor  20  comprises the detection layer  16  in each of the detection areas  2 ,  4 ,  6 , as well as an antenna  22  connecting each detection layer  16  to an electronic unit  28 , via a flexible sheet  24  formed by a lug of the transparent support  12  and a connector  26 . 
         [0056]    A protective layer  32 , which is optional and consisting of a varnish, is arranged on the side of the bottom surface  12   b  of the transparent support and covers the detection layer  16 , the decorative layer  14 , as well as the transparent support  12  at the pictogram  10 . 
         [0057]    Each of the light sources  18  is arranged facing the bottom surface  12   b  of the transparent support  12 , at each of the control areas  2 ,  4 ,  6 , in order to emit light through the transparent support  12  within the pictogram  10 . 
         [0058]    A method for producing the control device will now be described with respect to  FIGS. 3 to 8 . 
         [0059]    As represented in  FIG. 3 , the transparent support  12  having the top surface  12   a  and the bottom surface  12   b  is prepared. In an optional manner, the lug  24  may be provided for a later connection of the detection layer to the electronic unit  30 . 
         [0060]    Then, as represented in  FIG. 4 , an opaque ink layer is deposited by printing on the bottom surface  12   b  of the transparent support, in order to form the decorative layer  14 . Preferably, depositing the opaque ink layer is performed substantially on the whole bottom surface  12   b,  except for the pattern corresponding to the pictogram  10  of each detection area  2 ,  4 ,  6 . Depositing ink is advantageously performed by screen printing. A mask corresponding to the pattern of the pictogram allows preventing the presence of opaque ink and consequently of the decorative layer  14  on the other side of the pictogram  10 . The decorative layer  14  thus preferably has a substantially constant thickness in the order of 0.1 millimeters. 
         [0061]    Then, as represented in  FIG. 5 , an electrically conductive ink is deposited by printing on the decorative layer  14  around the pictogram  10  of each of the control areas  2 ,  4 ,  6 . The electrically conductive ink is advantageously deposited all around the pictogram  10 , to form the detection layer  14  and also between the detection layer  16  of each of the control areas  2 ,  4 ,  6  and the lug  24  to form antennas  22 . Preferably, the electrically conductive ink is deposited by screen printing and the same mask is used for preventing deposition of electrically conductive ink at the pictogram and ensuring that the inner edge  16   a  of the detection layer  16  corresponds closely to the outer edge  10   a  of the pictogram for each control area  2 ,  4 ,  6 . The conductive ink is advantageously produced with a copper or silver base. The detection layer  16  thereby produced is electrically conductive and preferably has a substantially constant layer in the order of 0.1 millimeters. 
         [0062]    Then, the protective layer  32  is applied against the entire bottom surface  12   a  of the transparent support  12 . 
         [0063]    Then, the detection device  1  formed by the transparent support  10  covered with the decorative layer  14 , the detection layer  16 , and optionally the protective layer  32  is arranged into a molding cavity  36  between a first portion  34   a  and a second portion  34   b  of a mold  34 . Plastic material is introduced in to the molding cavity  36  to produce the rigid support  30 , made of opaque plastic material, molded on the detection device  1 . 
         [0064]    Each light source  18  is then arranged facing the bottom surface  12   a  of the transparent support  10 , so as to be able to selectively illuminate the pictogram of each control area  2 ,  4 ,  6 . 
         [0065]    It should be noted that the light emitted for each light source  18 , is isolated from the pictogram of the adjacent detection layer, due to the opacity of the rigid support  30 . 
         [0066]    In the represented embodiment, the light sources  18  are carried by the rigid support  30 . Alternatively, the light sources  18  may be carried by the transparent support  10 .