Abstract:
A tank is provided for an appliance. The tank has an inside chamber to be filled with a liquid and comprises a photo sensitizer for sterilizing liquid in the tank under the effect of light.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the priority of German Patent Application No. DE 20 2009 001 015.5, filed on Jan. 28, 2009, the subject matter of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a tank for an appliance, such as a household appliance, wherein the tank has an inside chamber to be filled with a liquid. 
         [0003]    Water has a germ-forming tendency when it comes in contact with ambient air. The water can be cleaned with the aid of chemical and physical cleaning processes. However, chemicals can oftentimes be used only with restrictions around household appliances since in most cases the chemicals cause the water to have a different taste, for example when chlorinating the water. In addition, using anti-bacterial chemicals frequently requires a precise dosing since the chemicals or their decomposition products subsequently can enter the human body. 
         [0004]    Additional and alternative chemical-physical processes for removing germs from the water through sterilization, UV radiation or by generating ozone, can be realized with household appliances only with the aid of additional apparatuses and high energy consumption. A filtration process furthermore requires frequent monitoring and replacement of the filters. 
       SUMMARY OF THE INVENTION 
       [0005]    It is therefore an object of the invention to provide a tank, in particular for household appliances, designed for storing water and other liquids, which simultaneously makes possible the cleaning and sterilization of liquids without requiring additional apparatuses or influencing the taste. 
         [0006]    The above and other objects are achieved according to the invention wherein there is provided, according to one embodiment, a tank for an appliance, the tank having an inside chamber to be filled with a liquid and comprising a photo sensitizer for sterilizing the liquid in the tank under the effect of light. 
         [0007]    The tank according to the invention which is filled with liquid, and used in particular for household appliances, is therefore provided with photo sensitizer molecules in addition to the traditionally used materials. Germs are consequently removed from the water or other liquid through a catalytic process that produces in particular singlet molecular oxygen resulting from a photo-chemical reaction of the photo sensitizer molecules and absorption of discrete energy (light photons). This process prevents the growth of algae and fungus in the water container which occurs when the water or other liquid remains in the container over a longer period of time. The process furthermore kills bacteria that may be contained in the liquid. 
         [0008]    By incorporating photo sensitizers as components into the tank, it is possible to remove germs from the liquids contained inside the tank without having to use additional apparatuses, thereby making possible a universal application that is not tied to current. The tank can therefore be integrated into any type of liquid-carrying household appliance. The tanks according to the invention can furthermore also be mass produced. 
         [0009]    The molded body may be produced from a plastic material since this material has various advantageous material properties, for example it is easy to deform and is chemically inert to water. In addition, containers made of plastic are for the most part lighter than comparable containers made of steel. 
         [0010]    The molded body may be composed of a plastic material/photo sensitizer mixture, wherein the algae and bacteria are killed on the surface of the tank. Since the photo sensitizer is fixedly integrated into the plastic material, it cannot be removed on the one hand through abrasion during the mechanical cleaning while, on the other hand, it provides an optical effect caused by different color variants when using metal-coordinated photo sensitizers. 
         [0011]    According to a different embodiment, the inside surface of the molded body is coated at least partially with a photo sensitizer, for example in the form of a varnish. Singlet molecular oxygen, in particular, is thus produced along a large surface of the inside of the molded body as a result of a catalytic process, wherein the singlet molecular oxygen can subsequently come in direct contact with the liquid to be sterilized. If necessary, the coating can also be applied at a later date to an existing tank. 
         [0012]    The molded body may be at least in part light-permeable since daylight can thus be utilized in an ecological and efficient manner for the photo sensitizer. 
         [0013]    The color of the tank can furthermore be varied by adding different pigments. 
         [0014]    According to another embodiment, at least one photo sensitizer of the tank is a phthalocyanin. This category of macro-cyclical compounds is distinguished by its high thermal and chemical stability, protecting it against damage either resulting from the production of the tank or caused by substances during a possible chemical cleaning. The tank can therefore be cleaned in a standard dishwasher when it is dirty. Phthalocyanin agents are water insoluble and thus cannot be dissolved out of the tank material by water, so as to reach the human body. 
         [0015]    The effect of the photochemical reaction and the adjustment of the light energy absorption to a specific wavelength can be influenced favorably by coordinating the phthalocyanin agents with metal ions, such that a specific wavelength to be absorbed can be selected in dependence on the metal ion. As a result, the photo sensitizer molecules can be adjusted to specific lighting devices and lamps with restricted emission bands for the absorption and can thus be optimized. 
         [0016]    According to yet another embodiment, an additional optical effect may be created by coordinating aluminum, zinc, copper, cobalt or nickel ions with the aid of the phthalocyanin molecules to form coordination compounds which are subsequently present as pigments, for example colored blue or green, and which can absorb light of a complementary color. 
         [0017]    According to a further embodiment, there is provided a household appliance provided with a tank as described above, wherein the tank is embodied such that photo sensitizers are provided in the tank for sterilizing water and other liquids. 
         [0018]    The appliance may include LED lamps arranged on the tank or in the area surrounding the tank, so that the tank can be illuminated, thereby ensuring a continuous sterilization which does not depend on daylight. In contrast to regular light bulbs, LED lights have the advantage of low energy consumption in a restricted wavelength range, along with high light intensity. Thus, when adjusting the LED emitted radiation to the absorption wavelength of the photo sensitizer, a high conversion rate is obtained during the photo-chemical reaction, which consequently leads to an efficient sterilization of the respective liquid. 
         [0019]    According to another embodiment, the maximum emission of the emitted wavelength range for the LED lamps corresponds to the maximum absorption for the photo sensitizers, thus making available a high energy for the photo-chemical reaction, so as to catalytically produce in particular singlet molecular oxygen. 
         [0020]    The tank may be installed so as to be removable in a specially formed recess on the household appliance. The tank can thus be replaced in case of a defect, for example a break or a fissure. The option of removing the tank also allows refilling it at a different location with water or other liquids from a reservoir. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    These and other features and advantages of the invention will be further understood from the following detailed description with reference to the accompanying drawing. 
           [0022]      FIG. 1  is a schematic view of the outside of a household appliance including a tank according to the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]      FIG. 1  shows a household appliance according to one embodiment of the invention, in the form of a fully automated coffee maker  1 . This coffee maker is provided with a tank  2  consisting of a cover  3  and a molded body  4  made of plastic. The molded body furthermore contains added amounts of blue pigments which are generated through coordinating metal ions with a phthalocyanin, a photo sensitizer. As a result, the plastic molded body is translucent blue. The photo sensitizer absorbs electromagnetic radiation in the form of light and transfers this energy without radiation to atoms and molecules which are then put into an energy-rich state. 
         [0024]    A photo-chemical reaction takes place if germ-containing water is filled into the tank  2 . Following the absorption by the photo sensitizer of electro-magnetic radiation, emitted by the ambient light that acts upon the tank or by the LED lights  5 , catalytic singlet molecular oxygen and short-lived radicals are produced which cause the resulting killing of the germs, the necrosis and the apoptosis. 
         [0025]      FIG. 1  shows LED lights  5  that may be installed below the tank. The automatic coffee maker heats up the water that is now free of germs, a coffee grinder  6  grinds up the coffee beans and then releases the coffee grounds to a brewing device. Following the brewing operation, an outlet unit  7  dispenses the brewed coffee into a cup or mug. 
         [0026]    The cup or mug holding the coffee rests on a drip catching device  8 . 
         [0027]    Although the tank described above is used in connection with an automatic coffee maker, such a tank may also be used for other beverage dispensers, in particular if there is a long-term exposure of water to air which results in germ formation. 
         [0028]    Additional options for use can be found in the area of drinking water dispensers where the water is delivered in pre-filled tanks. 
         [0029]    Small cooling units, for example in the form of filled plastic ice balls, can furthermore also be attached to a tank or inserted so as to float in the tank, wherein the plastic coverings of the permanent ice balls are provided with a photo sensitizer. 
         [0030]    A high germ count must be expected in water tanks that are used in steam cleaners, in particular if water vapor is sucked in following the blowing out of the water vapor and the surface cleaner. The germs which are sucked back in can subsequently spread in the moist and warm environment of the steam cleaner. The use of a tank according to the invention can for the most part correct this problem. 
         [0031]    The same problem is encountered when using high-pressure cleaning devices which sometimes are not used for longer periods of time, thus allowing germs to multiply as a result of residual moisture inside the apparatus. 
         [0032]    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.