Patent Publication Number: US-7717106-B2

Title: Baking oven

Description:
The invention relates to a baking oven having a lighting device for lighting a cooking area. 
   Such baking ovens are generally known. 
   Furthermore, U.S. Pat. No. 5,909,950 shows a refrigerator door handle which carries a contact sensor which, when touched by a user, switches on an interior lamp in the refrigerator. The interior lamp is controlled by a switch which recognises whether the door is open or closed. The lamp remains switched on until the refrigerator door is closed again. 
   The object to be solved by the invention is to construct the lighting of the cooking area such that it is more versatile in use. 
   This object is solved according to the invention by the features of claim  1 . 
   The invention thus especially relates to a baking oven having a lighting device for lighting a cooking area and having a lighting control device for switching on, holding the switched-on state and switching off the lighting device in accordance with a pre-determined time profile which defines the increasing, holding and reducing of the lighting intensity, characterised in that the lighting control device has at least two different time profiles for increasing, holding and reducing the lighting intensity, and that the time profile to be respectively used by the lighting control device depends on the type of operation leading to the switching on of the lighting device. 
   As a result of the design of a lighting device for cooking areas of baking ovens according to the invention, the times for increasing, holding and reducing the lighting intensity can be varied in such a way that the respective times depend on the type of operation leading to switching on the lighting. 
   Thus, when switched on by a door switch, the lighting can be increased very rapidly, e.g. if good lighting is desired immediately on opening the cooking area door. Furthermore, the light can be held at a maximum lighting intensity for a very long time because, for example, when the door is opened for a longer time, the user presumably would like to handle the food being cooked in the cooking area or clean the cooking area and requires continuous lighting for this. After the holding time has elapsed, the lighting intensity can be reduced very slowly again and it can thereby be indicated to the user that the lighting device is not switched off by a fault but automatically in the correct fashion. A slow or very slow increase in the lighting intensity and a slow or very slow reduction of the lighting intensity means that the increase and/or reduction in the lighting intensity takes place along a lighting intensity time ramp of a time profile (diagram curve). In the event of a fast change in the lighting intensity, the ramp is steep. A very fast change means an abrupt rise or an abrupt fall in the lighting intensity, instead of over a lighting intensity time ramp. 
   According to a further embodiment of the present invention, instead of this or at the same time, for another type of usage it can be provided that after a brief contact of the door handle, the lighting intensity is increased moderately fast (ramp) to a maximum brightness, held there for a short time and then reduced rapidly again (steep ramp or sudden reduction in lighting intensity without ramp). In this case the customer presumably merely wishes to look briefly through a door window into the cooking area of the baking oven to check on the progress of the cooking process in the cooking area. 
   In the same or another embodiment it can furthermore be provided that when operating the baking oven using a function switch, an individual time profile is provided which optimally corresponds to the time profile pre-determined via the function switch. For example, a certain cooking process of the food to be cooked can be switched on by the function switch of the baking oven wherein the lighting of the cooking area is automatically switched on according to a time profile matched to this cooking process, the lighting intensity is increased, held and reduced again on switching off. 
   According to a further feature of the invention, it can be provided that the lighting is not increased to maximum brightness respectively suitable for the application. Instead, the brightness is left at a lower brightness, e.g. for permanent lighting of the cooking area, in order to display certain operating states to the customer. For example, the lighting intensity of the cooking area lighting can remain automatically switched on at the lower lighting intensity during the entire cooking process in order to make the food being cooked better visible to the user through the cooking area window and thereby also signal to said user than the cooking process in the cooking area is proceeding correctly. 
   The advantage of the invention: a cooking area lighting individually matched to the respective type of operation can be offered to the customer. 
   Further features of the invention are contained in the dependent claims: 
   Accordingly, a particular embodiment of the invention consists in the fact that at least two different time profiles are provided which have differences in the increasing of the lighting intensity from a minimum value to a maximum. A further embodiment of the invention consists in the fact that at least two different time profiles are provided which have differences in the reducing of the lighting intensity from a maximum value to a minimum. 
   A further embodiment of the invention consists in the fact that at least two different time profiles are provided which have differences in the holding of the lighting intensity. 
   A further embodiment of the invention consists in the fact that the time profiles have differences in the rising ramp of the increase and/or in the falling ramp of the decrease and/or in the value of the lighting intensity in the increased and/or in the reduced state. 
   A further embodiment of the invention consists in the fact that a door opening signal element is provided to signal an opening of the cooking area door to the lighting control device, wherein the door opening signal element is an element which can be actuated by the cooking area door depending on the door position or an element of a door handle of the cooking area door, which can be actuated manually to open the cooking area door. 
   A further embodiment of the invention consists in the fact that the lighting control device is constructed to switch on the lighting device on receiving a door-opening signal from the door opening signal element, which signals an opening of the cooking area door, and hereby increase the lighting intensity from a minimum value to a maximum value at a fast or very fast speed. A further embodiment of the invention consists in the fact that the lighting control device is constructed to reduce the lighting intensity from the maximum value to a minimum value after a pre-determined holding time during which the lighting intensity was held at a maximum value after switching on the lighting device, wherein the holding time begins on reaching the maximum value when switching on and runs automatically if the cooking area door is not opened during this holding time but does not run if the cooking area door is opened during the holding time in which case the holding time is automatically started again by the lighting control device after subsequently closing the cooking area door. 
   A further embodiment of the invention consists in the fact that the lighting control device is constructed to reduce the lighting intensity from the maximum value to the minimum value at a very slow or slow second speed depending on a lighting intensity time ramp of the time profile. 
   A further embodiment of the invention consists in the fact that the lighting control device is constructed to distinguish whether in one case the door handle signal element is actuated manually for a pre-determined long first minimum time as a sign for an opening of the cooking area door or in the other case, the door handle signal element was actuated manually only for a pre-determined short second minimum time as a sign that a person wishes to switch on the lighting device of the cooking area without opening the cooking area door, wherein in one case the lighting intensity is increased at a fast or very fast speed with a steep rising ramp or abruptly and the lighting intensity is reduced on switching off the lighting device at a slow or very slow speed with a flat descending ramp of the time profile, but in the other case the lighting intensity is increased from a minimum value to a maximum value at a moderate or fast speed on a rising ramp or suddenly, is then held for a short minimum time at the maximum value and is then reduced at a fast speed on a ramp or abruptly from the maximum value to the minimum value again. 
   A further embodiment of the invention consists in the fact that for at least one or a plurality of function switches at which respectively one cooking area heating function can be switched on by a person, the lighting control device has its own time profile for increasing, holding and reducing the lighting intensity of the lighting device of the cooking area, according to which when the function switch is actuated, the cooking area lighting is automatically switched on, increased, held at a maximum value for a pre-determined time and then reduced again and switched off. 
   A further embodiment of the invention consists in the fact that the time profiles are stored in the lighting control device or are pre-defined by an electronic circuit or can be generated by the lighting control device using a computer program depending on the type of operation by which the lighting device of the cooking area is switched on. 
   A further embodiment of the invention consists in the fact that the door opening signal element of the door handle is a contact sensor which responds to manual contact. 
   A further embodiment of the invention consists in the fact that at least one of the time profiles has a lighting intensity time increasing ramp for increasing and/or a lighting intensity time ramp for reducing the lighting intensity. 
   A further embodiment of the invention consists in the fact that at least one time profile is provided according to which the lighting intensity is held at a lower value compared with the maximum, which lies above zero, for permanent lighting in the cooking area. 

   
     The invention is explained below with reference to the drawings using preferred embodiments as examples. In the figures 
       FIG. 1  is a schematic diagram showing a vertical cross-section through a baking oven according to the invention, 
       FIG. 2  is a time profile diagram, 
       FIG. 3  is another time profile diagram, 
       FIG. 4  is yet another time profile diagram and 
       FIG. 5  is yet another time profile diagram, as examples of time profiles of which at least two different time profiles according to the invention are used by a user depending on the type of operation of the baking oven. 
   

   The baking oven  2  according to the invention shown in  FIG. 1  can be an electric baking oven or a gas baking oven in the form of an independent appliance or a built-in appliance for building into a household appliance or into kitchen furniture. 
   The baking oven  2  contains a lighting device  4  for lighting a cooking area  6  and a lighting control device  8  for switching on, holding the switched-on state and switching off the lighting device  4  according to a pre-determined time profile. The time profile defines the increasing, holding and reducing of the lighting intensity. 
   The baking oven  2  furthermore contains a cooking area door  10  with a door handle  12 , a fan  14  and an electric or gas-operated heating device  16  for heating the cooking area  6  under the control of a baking oven control device  18 . 
   The baking oven control system  18  and the lighting control device  8  can be two separate devices or jointly one combined device. 
   At one or a plurality of function switches  22 , respectively one of a plurality of cooking programs can be selected at the baking oven control device  18  for cooking food to be cooked in the cooking area  6 . The cooking area can be constructed for baking, roasting, grilling, heating or otherwise treating food to be cooked. Corresponding cooking programs can be switched on by means of the function switch  22  on the baking oven control device. The function switch  22  can be a rotatable or rotary pluggable toggle or a contact sensor. Different time profiles can be provided for each cooking program or for groups of cooking programs. These can be matched to the cooking processes and thereby show the user in which operating situation the cooking area is. 
   A switch  24  on the baking oven body can be actuated by the cooking area door  10  when said cooking area door  10  is opened and closed. The switch  24  notifies the lighting control device  8  respectively when the cooking area door  10  is opened or closed and when it is open or shut. 
   At the same time or alternatively, the door handle  12  or a part thereof can be constructed as a switch or contact sensor which notifies the lighting control device  8  respectively whether manual contact takes place for a short time or longer. 
   The lighting control device  8  has at least two different time profiles for increasing, holding and reducing the lighting intensity of the lighting device  4  in the cooking area  6 . The time profile to be used in each case by the lighting control device  8  depends on the “type of operation” which resulted in switching on the lighting device. 
   Examples for “types of operation” are: opening the cooking area door  10 ; closing the cooking area door  10  again after a short opening time; closing the cooking area door  10  again after a longer opening time; brief contact of the door handle  12  to thereby signal to the lighting control device  8  that a brief switch-on of the lighting device  4  without opening the cooking area door  10  is desired wherein the door handle is a switch or contact sensor which signals a manual contact of the lighting control device; a longer manual contact of the door handle  12  relative thereto (and if necessary opening of the cooking area door  10 ) to thereby signal to the lighting control device  8  that the cooking area door  10  will be opened or has just been opened, wherein the door handle is a switch or contact sensor which signals a manual contact of the lighting control device; actuating the function switch  22  in order to select or switch on a desired cooking program at the baking oven control device  18 ; actuating a lighting switch or lighting sensor  26  as a function element at which a user can adjust the lighting device  4  by means of the lighting control device  8  regardless of whether the cooking area door  10  is in the closed or open position. This is merely a list of examples and does not exclude other “types of operation” to which, according to the invention, a specific time profile is respectively assigned for increasing, holding and reducing the lighting intensity when switching on, holding and switching off the lighting device  4 . 
     FIGS. 2 to 5  show examples of various time profiles of which one time profile each can be assigned to a particular type of operation. 
   The time profiles in  FIGS. 2 to 5  show the time on the abscissa and the lighting intensity on the ordinate. In this case, it was assumed that when switching on, the lighting device is in each case switched on from zero (min=0) to a maximum value (max) of the lighting intensity (brightness). According to the invention, however it is also possible to have time profiles by which, for example for a permanent lighting state during the cooking process in the cooking area  6 , the lighting device  4  is switched on to a reduced lighting intensity “max/x”. 
     FIG. 2  shows a time profile  32  according to which the lighting device  4  is switched on at the time t 1 , but in this case the lighting intensity does not increase abruptly to the maximum value max but according to a lighting intensity time ramp  34  with an angle of inclination α. The maximum lighting intensity is reached at the time t 2  and then maintained until the time t 3  which is represented by a time profile section  35 . At the time t 3  the lighting device  4  is switched off wherein the lighting intensity is not switched off abruptly but is slowly shut down according to a descending ramp  36  at an angle β until the next time t 4 . 
     FIG. 3  shows another time profile  43  according to which the lighting device  4  is abruptly switched on at maximum lighting intensity at the time t 1  and abruptly switched off to zero at the time t 4 . As a result, a vertical ascending flank  44  is obtained, then a horizontal time profile section  45  and then a vertical descending flank  46 . 
     FIG. 4  shows a time profile  53  with an ascending ramp  34  the same as or different to that in  FIG. 2  and an abruptly descending switch-off flank  46  according to  FIG. 3  and a time profile section  55  running horizontally between the times t 2  and t 4 . 
     FIG. 5  shows a time profile  63  with a switch-on flank  44  which rises abruptly from zero to the maximum value at time t 1  in accordance with  FIG. 3 , then a horizontal time profile section  65  as far as the time t 3 , and then a descending time profile ramp  36  with an angle of descent β the same as or different to that in  FIG. 2 . 
   Further time profiles can for example consist in the fact that the ascending and/or the descending time profile section runs convexly or concavely instead of rectilinearly and/or the horizontal section  35  or  45  or  55  or  65  in  FIGS. 2 to 5  is missing, with the maximum lighting intensity (max) being reduced again immediately after reaching said intensity so that a ramp-shaped increase in the lighting intensity (e.g. ramp  34  in  FIG. 2  or  FIG. 4 ) is followed by a ramp-shaped reduction of the lighting intensity (e.g. time profile section  36  in  FIGS. 2 and 5 ) or a sudden switch-off and thus a vertical time profile section  46  in accordance with  FIGS. 3 and 4 . Similarly, it is possible to have a time profile in which a vertical increasing time profile section in accordance with  44  in  FIGS. 3 and 5  is followed by a ramp-shaped decreasing section (e.g. ramp  36  in  FIGS. 2 and 5 ). 
   The ramp angles α and/or β can be the same or different in all time profiles. 
   The “maximum values” specified in the description and in the claims can correspond to the highest permissible electrical current intensities of the lighting device or lower values. The “minimum values” specified in the description and in the claims preferably mean “completely switched off” and thus zero lighting intensity but can however also mean a low lighting intensity having an above-zero value.