Abstract:
A water tank for a household device includes a tank container with a bottom and side walls. At least one of the side walls includes filling-level markings that comprise a profiling formed integrally with the at least one side wall.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the priority of German Patent Application DE 20 2012 103 939.7, filed on Oct. 15, 2012, the subject matter of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a water tank for a household device, in particular used for the beverage preparation, comprising a tank container with a bottom and side walls, wherein a filling level marking is provided on at least one side wall. 
         [0003]    Devices used for the preparation of beverages are available which comprise a tank container provided with a filling level indicator. The tank container can be manufactured from a transparent plastic material, and the filling level indicator can then be affixed later on by printing it on or with the aid of a thermal transfer. However, the steps for affixing readable filling level markings by printing or by thermal transfer are relatively involved. In addition, a filling level indicator of this type is optically not very appealing. 
       SUMMARY OF THE INVENTION 
       [0004]    It is therefore an object of the present invention to make available a water tank provided with filling level markings which are easily produced and which are optically appealing. 
         [0005]    The above and other objects are achieved according to the invention wherein there is provided, according to one embodiment, a water tank for a household device, including: a tank container with a bottom and side walls, wherein at least one of the side walls includes filling-level markings that comprise a profiling formed integrally with the at least one side wall. 
         [0006]    According to the invention, the filling-level marking is formed integrally with the side wall of the tank container in the form of a profiling which can be produced easily, for example when using a molding or forming process to produce the tank container, such as the injection-molding technique. A post-processing step is thus omitted, e.g. a printing or a thermal transfer of the markings. Optically appealing effects can furthermore be achieved with the aid of the profiling of the side wall and through the guidance of the light. 
         [0007]    According to one embodiment of the invention, the profiling comprises at least one surface which is oriented at an angle greater than 30°, in particular greater than 45°, to the plane for the side wall. As a result, the profiling remains easy to see since the refraction of the light differs noticeably from that of the remaining flat surface of the side wall. The profiling in this case can be formed by a groove-type recess for which a part of the surface is embodied essentially at a right angle to the plane for the side wall. The groove-type recess can have a concave curvature, so as to also ensure a directed guidance of the light in the bottom region of the recess. 
         [0008]    For an effective production, the tank container can be produced from a plastic material and with the aid of the injection-molding process. A transparent or translucent plastic material is selected for this, at least for the region of the side wall containing the filling-level markings. The side wall in this case can have a thickness ranging from about 2 to 4 mm, wherein the depth or the height of the profiling is in the range of about 0.2 to 1 mm, especially 0.4 to 0.7 mm. However, the profiling can also be embodied so as to project toward the outside instead of as a recess. The profiling can furthermore be embodied on the inside or the outside, wherein an arrangement on the outside is more advantageous for cleaning reasons. 
         [0009]    According to a different embodiment of the invention, there is provided a household device used, for example, for the preparation of a hot beverage, which includes the water tank according to the invention. The household device can comprise at least one lighting device which radiates light into a side wall of the tank container for illuminating the filling-level markings. For a better distribution of the light, a light guide can be arranged between the water tank and the lighting device. With the aid of such a light guide, it is possible to purposely illuminate a strip-type section of the tank container provided with the filling-level markings in the form of profiles. 
         [0010]    The light can thus be radiated in from above, from below, or from the side, wherein an illumination from below is preferable. 
         [0011]    According to another embodiment, the light is radiated in, essentially in the direction of the plane for the side wall containing the filling-level markings, wherein as a result of the profiling of the filling-level markings, the light is emitted at an angle ranging from about 30° to 150°, in particular from about 45° to 135°, to the plane for the side wall, thus making available an appealing optic which is still visible even from a longer distance. 
         [0012]    As used herein, “about” means approximately, near or close to a number, that will still achieve effectiveness in the context in which a number is used as would be apparent to a person of ordinary skill in the art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    These and other features and advantages of the invention will be further understood from the following detailed description of embodiments with reference to the accompanying drawings, which show in: 
           [0014]      FIG. 1A  view from the side of a household device according to the invention, provided with a water tank; 
           [0015]      FIG. 2A  view from the side of the household device according to  FIG. 1 ; 
           [0016]      FIG. 3A  sectional view through the water tank according to  FIG. 2 ; 
           [0017]      FIG. 4A  detail view (enlarged) of the profiling on the water tank; 
           [0018]      FIG. 5A  schematic view of the light guidance at the profiling according to  FIG. 4 ; 
           [0019]      FIG. 6A  sectional view through a detail of the water tank shown in  FIG. 1 , in the lower region of the water tank; 
           [0020]      FIG. 7A  partial sectional view from the side of the water tank in  FIG. 1 , and 
           [0021]      FIG. 8A  sectional view of a detail, showing the introduction of the light into the water tank. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    Referring to  FIG. 1 , there is shown a household device  1  in the form of a coffee machine comprising a tank container  2  into which water is filled and which is connected to a brewing unit  3 , by means of which the water is conducted via a line  4  into a filter holder  5 . Arranged below the filter holder  5  is a carafe  6  for holding the freshly brewed coffee which is positioned on a warming plate  7 . 
         [0023]    As can be seen from the enlarged representation in  FIG. 2 , the tank container  2  is provided with filling-level markings  13  on one side wall  10 . Fixing projections  8  may be provided in a bottom region of the tank container  2 , so that the tank container  2  can be positioned precisely on the brewing unit  3 . The tank container  2  may be provided with a filling opening  9  on the top. 
         [0024]    The filling-level markings  13  are embodied as profiled sections in the form of groove-type recesses. Simple lines are inserted as filling-level markings  14  while the numbers  15  are arranged adjacent thereto and indicate the brewing amount in the form of the number of cups. The numbers  16 , which indicate the amount of water in liters, form additional filling-level markings. The filling-level markings can be embodied on the side wall  10  in a manner that conforms to the customs of the respective country. 
         [0025]      FIG. 3  shows that the tank container  2  has a side wall  10 , provided with the filling-level markings  13 , as well as an opposite-arranged side wall  12  which does not have any filling-level markings, wherein filling-level markings  13  can optionally also be provided on several side walls  10 . The side walls  10  and  12  are connected via a bottom section  11 . 
         [0026]    The tank container  2  is composed of a transparent or translucent plastic and may be produced with an injection-molding technique. The thickness d of the side wall  10  with the filling level markings  13  in this case ranges from about 2 to 4 mm, while the depth of the profiling  14  for the filling-level markings ranges from about 0.2 to 1 mm, in particular about 0.4 to 0.7 mm. The width s of the profiling  14  is also in the range of about 0.2 to 1.4 mm, in particular of about 0.4 to 1 mm. 
         [0027]      FIG. 4  shows an enlarged sectional view of a profiling  14  for filling-level markings  13 . In this example, the profiling  14  is embodied as a groove-type recess that comprises two side walls  17  oriented substantially at a right angle to a surface of the side wall  10 . Both side walls  17  are connected via a curved section  19  to a bottom  18  of the profiling. 
         [0028]    An edge-type, angular transition is consequently avoided between the side wall  17  and the bottom  18 . As shown in  FIG. 5 , incident light rays  20  which are generated by a light source are refracted in the region of the side wall  17  and the curvature  19  in the area of the boundary surface, meaning the surface of the side wall  17  and the curvature  19 . The light rays  21  therefore exit essentially parallel-bundled toward the observer and the observer can see the profiling  14  better since the side wall  17  and the curvature  19  appear to be brighter than the surrounding area. 
         [0029]    In  FIGS. 6 and 7 , the bottom  11  of the tank container  2  is shown in an installed position. Provided inside the brewing unit  3  is a lighting device  24  in the form of a light-emitting diode, which radiates light into a plate-shaped light guide  25 . The plate-shaped light guide  25  conducts the light to a projection  26  on the bottom  11  of the tank container  2 , wherein the light guide  25  is oriented at an angle a to the plane for the side wall  10 , so that the incident light is easily radiated toward the outside. The angle a preferably is in the range of about 1° to 20°, in particular about 5° to 15°. As a result of the arrangement of the lighting device  24  and the light guide  25  inside the brewing unit  3 , a housing wall  22  of the brewing unit  3  can serve to support the tank container  2 , wherein the housing wall  22  engages in a groove-type recess in the bottom  11 . Furthermore arranged below the side wall  12  are a recess  23  for accommodating a housing wall  22  and a fixing projection. 
         [0030]    As shown in  FIG. 7 , the light guide  25  is arranged below the filling-level markings  13 , so that light is radiated in from below, essentially in the form of striations, via a partial section of the side  10 . As a result, the readability and the contrast to the surrounding areas are further increased. 
         [0031]      FIG. 8  schematically illustrates the path traveled by the light rays emitted by the lighting device  24 . A light ray  30  travels from the lighting device  24  into the light guide  25  and is refracted on the front exit surface of the light guide  25 . Upon entering the projection  26  on the underside of the tank container  2 , a further refraction takes place and a light ray  32  then travels to the filling-level markings  13 . There, the light ray impinges on the profiling and is refracted one more time when it exits from the tank container  2 . To make it possible for the light ray coming from the light guide  25  to enter the tank container  2  with the lowest possible loss of intensity, the exit surface on the light guide  25  and the entry surface on the projection  26  are arranged at an angle β which depends on the refractive index for the materials and can range from about 10° to 45°. 
         [0032]    For the exemplary embodiment shown herein, the tank container  2  is illuminated only in the area of the filling-level markings  13 . Of course, it is also possible to provide a large-surface illumination of the tank container  2  in order to achieve special optical effects. In addition, the light can also be radiated in from the top or from the side, instead of from the bottom, so as to optically emphasize corresponding filling-level markings. 
         [0033]    For the exemplary embodiment shown herein, the tank container was used as a component of a coffee machine. Of course, the tank container can also be used for other household devices, in particular used for the beverage preparation. 
         [0034]    It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.