Abstract:
A device for heating or keeping food warm. The device comprises a housing having at least one opening for inserting or removing food, an interior space formed by the housing, and at least one electromagnetic radiation source disposed in the interior space of the housing for emitting heat radiation. The device is characterized in that at least one UV light source for emitting UV radiation is disposed in the interior space of the housing, which enables a UV disinfecting of the interior space.

Description:
FIELD OF INVENTION 
       [0001]    The invention concerns a device for heating or keeping food warm by means of an electromagnetic radiation source for emitting heat radiation. 
       BACKGROUND OF THE INVENTION 
       [0002]    Devices for heating or keeping food warm (the food is typically located on or in a container for cooking or serving, e.g., a dish) are used in the field of gastronomy, for example in fast food restaurants. Aside from heating and keeping food warm, such devices can also contribute to the attractive presentation of food. In addition to conventional electric heating elements, such as heating coils made of metal that can be heated, electromagnetic radiation sources, particularly infrared lamps, have come into use, which subject the food to infrared electromagnetic radiation. 
         [0003]    The advantage of using electromagnetic radiation sources is that such sources provide higher energy efficiency, a uniform heat distribution and the simultaneous illumination of the food. 
         [0004]    A food display that can be heated by means of infrared lamps is disclosed in GB 2 349 454 A, in which a specially designed radiating panel in front of the radiation source provides for a favorable radiation characteristic of the electromagnetic radiation. In order to protect operating personnel from possible injury through contact with hot housing components, it is proposed that metal or wire mesh screens surround the hot regions, or that the food is placed on nylon trays. 
         [0005]    Devices for keeping food warm are described in EP 2 286 702 A1 and U.S. Pat. No. 3,448,678. Thermal light sources are described in both documents, the spectrums of which can also approach the ultraviolet range. These light sources, however, have no antimicrobial effect, as they are designed exclusively as heat sources. 
         [0006]    Aside from the danger of injury through coming into contact with hot housing components, there is a further disadvantage in that germs can enter the storage zone through the open front end of the food display. This is a problem, in particular, during prolonged presentation of the food, and for those regions of the storage zones having only moderate holding temperatures. 
         [0007]    It is an objective of the present invention to provide a device of the above-mentioned type, which reduces the disadvantages described above and which meets higher demands with regard to hygiene and workplace safety. 
         [0008]    According to the present invention, this objective is attained by means of a device having the features of the independent claim(s). Advantageous designs and further developments can be derived from the dependent claims. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention provides a device for heating and keeping food warm that comprises a housing having at least one opening for loading or removing the food, an interior space formed by the housing, and at least one electromagnetic radiation source for emitting heat radiation. The at least one electromagnetic radiation source is arranged in the interior space of the housing. According to the present invention, the device is characterized in that at least one UV light source for emitting UV radiation having a disinfecting effect is disposed in the interior space of the housing. In this context, a UV light source for emitting UV radiation having a disinfecting effect is to be understood as a UV light source, which emits a particularly large amount of light in a range of the UV spectrum which, through its properties with respect to the spectrum and intensity, deactivates microbes, and if necessary, can also destroy other organic substances. By this means, a simple and effective UV disinfection of the interior space can be carried out, and the microbial pollution of the working surfaces and the air in the interior space can be effectively reduced. 
         [0010]    Preferably, the UV light source generates a UV radiation spectrum, exhibiting peaks at 254 nm and/or at 185 nm, which ensures a particularly effective disinfection. A UV radiation of this type can, for example, be generated by means of one or more low pressure mercury vapor lamps. 
         [0011]    Depending on the mounting of the UV light source in the housing, it is possible to ensure that the UV light source is surrounded, at least in part, by a hollow mirror, which is oriented such that an emission of UV light from the interior space is prevented, such that the operating personnel are not exposed to any hazardous UV radiation. 
         [0012]    A particularly reliable protection for the operating personnel is provided if the interior space can be closed in a lightproof manner during the UV treatment. For this, one can provide that a front opening of the housing and/or a back opening of the housing can be closed with a flap that is opaque to UV light. The flap and/or the housing can include sensors and/or contacts, which ensure that the flap is in the closed position before the UV light source can be activated. The sensors/contacts are thus designed such that the UV light source is deactivated when then flap is open. 
         [0013]    The UV light source can comprise a control logic, which is disposed in the lower region of the housing, for example. The control logic is preferably designed as a removable module, which reduces the effort required for maintenance and service. 
         [0014]    The UV light source can be operated continuously or intermittently. By way of example, the UV light source can be controlled by means of a timer in the control logic. 
         [0015]    According to a preferred embodiment of the present invention, the housing comprises a cooling device for cooling one or more parts of the housing. Preferably, at least those parts of the housing that the operator can come in contact with when loading or removing food are cooled. The housing can be made of a wide variety of materials, but is typically made, at least in part, of stainless steel. 
         [0016]    The cooling device can comprise an electric cooling system, which includes, for example, Peltier elements or a coolant system having a heat exchanger. However, in many cases the ambient air passing over the parts of the housing that are to be cooled already acts as an effective coolant. For this reason, the cooling device advantageously comprises ventilation means, which draw air from the surrounding area and conveys the air along the parts of the housing that are to be cooled. In the context of the present invention, “ventilation means” comprise, in particular, rotating fans, designed, for example, as a tangential or cylindrical fan. The parts of the housing that are to be cooled typically comprise at least a part of the housing that surrounds the at least one opening. 
         [0017]    In a further development of the device according to the present invention, the at least one opening is disposed on the front side of the housing. The ventilation means can be disposed thereby in a crossbar that defines the top boundary of the at least one opening. 
         [0018]    According to the present invention, the ventilation means generate an air current that runs substantially parallel to a plane that extends across the opening. In particular, the air current can be directed vertically downward toward the lower boundary of the opening. In the context of the present invention, “substantially parallel” means that a small angle may exist between the plane that extends across the opening and the air current running past the plane. The air current, in general, is not perfectly parallel, but instead, diverges slightly in its path from the ventilation means. This air current, which is heated through contact with the parts of the housing that are to be cooled, forms, to some extent, a “warm air curtain” at the opening of the housing, which prevents colder ambient air from entering the interior space of the housing. As a result, the food that is to be heated is prevented from cooling off, and it becomes difficult or impossible for particles or microorganisms and other contaminants from the surrounding area to enter the interior space having the food located therein. 
         [0019]    In one embodiment of the device according to the present invention, the interior space is divided by intermediate shelves into multiple compartments that are spaced apart in a substantially vertical orientation, wherein an opening is associated with each compartment. In the context of the present invention, “substantially vertical” means that the compartments may be oriented at a slight inclination. For example, compartment shelves that are slightly inclined with respect to a horizontal direction make it possible that the individual compartments can be loaded with food through a loading opening, which then slide along the inclination of the compartment shelf toward a removal opening on the opposite side. In this case, both the loading opening, as well as the removal opening, can be provided with a warm air curtain of the type described above. Each of the compartments can form a separate interior space and can include one or more electromagnetic radiation sources and ventilation means. Moreover, the openings can be closable by means of flaps or covers. 
         [0020]    In a further development of the device according to the present invention, the air current also flows in a substantially horizontal direction into the interior space, wherein in the context of the invention, “substantially horizontal” allows for a slight inclination of the compartments. The air current flows, thereby, either along the upper inner wall of the housing and/or the lower surface of the intermediate shelves or through channels formed in the upper inner wall of the housing and/or in the intermediate shelves. In doing so, the air current at the rear side of the housing is deflected downward. 
         [0021]    The ventilation means in the device according to the present invention can comprise a ventilation element, which includes a ventilation fan mounted in a hollow chamber provided with ventilation vents. 
         [0022]    Typically, the electromagnetic radiation source is attached to, or integrated in, the upper inner wall of the housing and/or the lower sides of the intermediate shelves. The number of electromagnetic radiation sources and the positioning thereof can be adapted thereby to the demands, for example, the distribution of the food that is to be kept warm, or the cost of the device. 
         [0023]    Advantageously, the electromagnetic radiation source is designed as a halogen lamp and can emit one or more wavelength ranges in the infrared spectrum. The electromagnetic radiation source is, in particular, optimized for the wavelength ranges which preferably are absorbed by food, for example, in the microwave range. The spectral components can comprise a range in the visible light spectrum, for illuminating the food. 
         [0024]    The invention shall now be explained in greater detail, based on preferred embodiments, with reference to the attached drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1  shows a perspective view of an embodiment example of the device according to the present invention; 
           [0026]      FIGS. 2   a  and  2   b  show sectional views of two embodiment examples of the device according to the present invention; 
           [0027]      FIG. 3   a  shows a partially disassembled ventilation element, as it can be incorporated in a ventilation means for the device according to the present invention; 
           [0028]      FIG. 3   b  shows the ventilation element from  FIG. 3   a , in its assembled state; and 
           [0029]      FIG. 4  illustrates the air current in an advantageous embodiment example of the device according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    In  FIG. 1 , a device according to the present invention, for heating or keeping food warm, is depicted. It will be appreciated that the food may be located on or in a container for cooking or serving the food (e.g., a dish). The perspective view shows a housing  10 , on a front side  12  of which compartments  23  are visible through two openings  14 . The compartments  23  form an interior space  20  of the housing  10 . The upper edge of each opening  14  contains a crossbar  15 , on which a cooling device  40 , in particular a ventilation means  41 , can be mounted. 
         [0031]    Through ventilation vents  45 , best seen in  FIGS. 3   a  and  3   b , an air current  42  generated by the ventilation means  41  can be directed downward, parallel to the plane that extends across the opening  14 . At the lower boundary of the opening  14 , the air current  42  flows over one or more parts  11  of the housing  10  that are to be cooled. These parts  11  of the housing  10  represent, in particular, sources of danger to the operating personnel that, through inattentive reaching into the interior space  20 , may burn the operating personnel. The air current  42  can be adjusted such that, on one hand, the temperature in the interior space  20  is high enough to keep the food warm, and on the other hand, is cool enough that the operating personnel will not burn themselves on the parts  11  that are to be cooled. By guiding the air current  42  substantially parallel to the plane that extends across the opening  14 , it is possible to simultaneously prevent an excess of heat from being discharged into the surroundings from the interior space  20  through convection. 
         [0032]    Electromagnetic radiation sources  30  are mounted on an upper inner wall  21  of the housing  10  and/or the undersurfaces of intermediate shelves  22 , which are hidden here, due to the perspective view. The present device can exhibit numerous other features for the presentation of food, which are not depicted here, for reasons of clarity. These comprise, in particular, additional lighting possibilities, as well as labels for the food, for the customers or the operating personnel. 
         [0033]    A sectional view of a simple embodiment of the device according to the present invention is shown in  FIG. 2   a . The housing  10  encompasses interior space  20 , which can be accessed by means of opening  14 . A cooling device  40  is mounted on a crossbar  15  defining a top boundary of opening  14 . The electromagnetic radiation source  30  is attached to the upper inner wall  21  of the housing  10 . 
         [0034]    A sectional view of another embodiment of the device according to the present invention is shown in  FIG. 2   b . In this example, the interior space  20  is divided into three compartments  23  by means of intermediate shelves  22 . Each of the compartments  23  has one opening  14  with integrated cooling device  40  at the front side  12 , and its own electromagnetic radiation source  30 , attached beneath the intermediate shelves  22  or the upper inner wall  21  in each case. A temperature control system  50  for controlling the electromagnetic radiation source  30  and/or for controlling the cooling device  40  is provided in the housing  10 . The temperature control system  50  comprises numerous temperature sensors  51  in the depicted example, for measuring the temperature in the interior space  20  of the housing  10 . The temperature sensors  51  are built into the upper surfaces of the intermediate shelves  22 , such that each compartment  23  can be controlled individually. 
         [0035]    Furthermore, two variations of the device according to the present invention are shown in  FIG. 2   b , which includes UV light sources  60  for disinfection. 
         [0036]    According to the first variation, each compartment  23  includes at least one UV light source  60 , which is at least partially surrounded by a hollow mirror  61 , which is oriented such that the respective intermediate shelf  22  can be irradiated with UV light, but wherein no UV light can exit through the opening  14  at the front side  12 , or an opening that is potentially provided at the back side  13 . By this means, injury to the operating personnel can be prevented. 
         [0037]    Because, however, it is not possible to entirely prevent the exit of UV light with the first variation, through reflection and scattering on the housing components, it is provided, according to a preferred variation, that openings  14  are closed by means of lightproof flaps  62  during a UV disinfection of the housing. The flaps  62  can be provided with appropriate UV light sources  60 , in addition to, or as an alternative to, the UV light sources  60  mounted in the interior space  20 . The flaps  62  can be permanently attached to the housing  10  by means of a hinge, or these can be separate components (as depicted in  FIG. 2   b ), which are only placed in the openings  14  and/or in corresponding openings on the back side  13  of the housing  10 , for the disinfection. 
         [0038]    The housing  10  can, for example, exhibit safety contacts  63 , connected to a UV control logic  64 , which ensure that the UV light sources  60  can only be activated when the flaps  62  are in place. The control logic  64  can also be designed such that individual intermediate shelves  22  can be disinfected separately, while other intermediate shelves  22  remain usable. The control logic  64  can, for example, form, together with the temperature control system  50 , a module  65  that can be removed to facilitate the maintenance thereof. If the flap  62  is designed as a separate component, then it can be provided, for example, with a handle  66 , which enables its simple placement in the opening  14 . The flap  62  can also exhibit an electrical contact  67 , which forms a connection with the corresponding safety contact  63  of the housing  10  when in the installed state, such that, even without control logic  64 , a reliable actuation of the UV light source  60  for the flap  62  is enabled. For this, the electrical contact  67  is connected to the UV light source  60  via an electric power supply line  68 , such that the UV light source  60  is activated when the flap  62  is placed in the opening  14  in the housing  10 . 
         [0039]    A ventilation element  43  is shown in  FIG. 3   a , in the form in which it can comprise a ventilation means  41  integrated in crossbar  15 , as shown in  FIGS. 1 ,  2   a , and  2   b . In a partially disassembled state in  FIG. 3   a , with a panel  47  removed, it is possible to see into a hollow chamber  44  behind the panel  47 , in which a blower  46  is located. The blower  46  typically comprises a blower motor  48 , and is designed as a tangential ventilator in the depicted example. The ventilation vents  45  provided on the lower surface of the ventilation element  43  enable a uniform air current  42  away from the ventilation element  43  when the blower  46  is rotating. The ventilation element  43  is depicted in the assembled state in  FIG. 3   b.    
         [0040]    The advantageous embodiment of the device according to the invention depicted in  FIG. 4  illustrates air currents  42  caused by the ventilation means  41 , in a lateral section. The blowers  46  integrated in the crossbars  15 , cause, on one hand, air currents  42  guided downward, which cover the openings  14  at the front side  12 , and on the other hand, generate additional air currents  42  in the interior space  20  of the housing  10 , parallel to the intermediate shelves  22  and to the upper inner wall  21 . The air currents  42  flowing against back side  13  of the housing  10  in the interior space  20  are deflected downward. 
         [0041]    The air currents  42 , directed downward to both the front side  12  as well as the back side  13  of the housing  10 , cause the interior space  20  and thus the storage areas lying in the compartments  23  to be surrounded by a warm air curtain. This warm air curtain makes it difficult, on one hand, for particles and microorganisms to enter the storage area, and on the other hand, prevents excessive heating in the region of the opening  14  of the housing  10 , by means of which, the danger of the operating personnel burning themselves on the housing  10  is reduced. 
         [0042]    As can be readily seen, through an appropriate design of the upper inner wall  21  and the intermediate shelves  22 , channels  24  can be formed, by means of a double floor, or flow grooves in the respective components, for example. The channels  24  can thus act against a divergence of the air current  42 , and contribute to an effective warm air curtain on the back side  13  of the housing  10  as well.