Abstract:
Apparatus and methodology is provided to control lighting associated with an appliance. Ambient light proximate the appliance and/or light from one or more lighting devices associated with the appliance is monitored and used to control the energization of the appliance lighting devices. Lighting device may include illumination devices as well as indicia display devices. The controller is configured to compensate lighting levels over the lifetime of the lighting devices to provide consistent lighting from the appliance lighting under all operating conditions.

Description:
FIELD OF THE INVENTION 
       [0001]    The present subject matter relates to lighting for appliances. More particularly, the present subject matter relates to control for all operating conditions of lighting associated with appliances. 
       BACKGROUND OF THE INVENTION 
       [0002]    In the life cycle of an appliance it is natural for the lighting systems to dim over time. This is generally true for LED&#39;s, LED Backlighting, vacuum fluorescent displays (VFDs), and other types of appliance lighting. Typically the driving method provided for appliance lighting is determined and set for the life of the appliance and is never changed. 
         [0003]    United States Patent Application Publication US 20080094518 to Bennett entitled “System and Method for Controlling TV Display Lamp Brightness” describes a remote control signal receiver for a TV that sends not only user-generated commands to the TV processor but also, when no commands are sensed, an ambient light signal that can be used to adjust the brightness of the TV 
         [0004]    United States Patent Application Publication US 20060149607 to Sayer et al. entitled “LED Lighting System” describes a method for optimizing an LED lighting system cost including determining LED costs, power source costs, and total costs associated with a plurality of LED quantities, and identifying a lowest total cost as an optimal cost. The disclosed LED lighting system includes an LED operated by a constant-current driver at less than its maximum current capacity. A programmable controller including a feedback routine is used to compensate for intensity drift as an LED ages. 
         [0005]    In view of these known concerns it would be advantageous to provide lighting systems that provide compensations that would make the appearance of appliance lighting systems more appealing for all ambient and life cycle conditions while at the same time offering operational power saving features. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0006]    Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. 
         [0007]    In some embodiments, the present subject matter relates to methodologies for providing compensation for light generation over the lifetime of a lighting device in an appliance. One or more lighting devices are installed in an appliance and one or both of ambient light proximate the appliance and lighting device conditions are monitored. Energization of the lighting devices is controlled to compensate for the monitored light condition so as to achieve compensation for existing conditions over the lifetime of the one or more lighting device. 
         [0008]    In certain of the methods plural lighting devices are installed but only a single one of the plural lighting devices is monitored. One or more of the plural lighting devices are controlled based on the monitored condition of the single monitored device. 
         [0009]    In certain embodiments of the method energization characteristics applied to the lighting devices are monitored and the devices are controlled based on the characteristics. In certain methods, the characteristics may correspond to at least one of time, type, or level of energization of the lighting devices. 
         [0010]    In selected embodiments, the method provides for monitoring ambient light proximate the appliance and energizing at least one of the plural lighting devices based on the monitored ambient light. 
         [0011]    In other selected methods, the method provides for monitoring light from one of the lighting devices and energizing at least one of the lighting devices based on the monitored light. 
         [0012]    The present subject matter also relates to an appliance including a controller and at least one lighting device. A driver is coupled between the controller and the lighting device. An optical sensor and a feedback network are provided to provide the controller with signals related to light levels. The controller is configured to receive the light signals and to control energization of the lighting devices. 
         [0013]    In certain embodiments the light signals may be indicative of ambient light while in others the signals indicate light levels from one of the lighting devices. In some embodiments, the apparatus includes at least two lighting devices. In these embodiments the controller is further configured to monitor at least one of the lighting devices and to control energizing of one or more of the lighting devices based on the monitored conditions. 
         [0014]    In certain embodiments the feedback network is configured to monitor energization characteristics applied to the lighting device. In these embodiments the controller is configured to cause the driver to energize one or more of the lighting devices based on the monitored energization characteristics. 
         [0015]    These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: 
           [0017]      FIG. 1  schematically illustrates a life cycle lighting compensation system in accordance with present technology; 
           [0018]      FIG. 2  schematically illustrates an ambient lighting compensation system in accordance with present technology; 
           [0019]      FIG. 3  schematically illustrates a light sensor and feedback arrangement for providing a light level signal to a controller; and 
           [0020]      FIG. 4  illustrates and exemplary appliance having a display with which the present subject matter may be incorporated. 
       
    
    
       [0021]    Repeat use of reference characters throughout the present specification and appended drawings is intended to represent same or analogous features or elements of the invention. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
         [0023]    As noted in the Summary section, the present subject matter is directed toward lifetime compensation for appliance lighting. As illustrated, in exemplary embodiments, the present subject matter may employ a controller and associated components and controlling software to determine ambient and system lighting conditions of an appliance and to adjust the system lighting conditions to compensate for given conditions. 
         [0024]    With reference now to  FIG. 1 , there is illustrated a life cycle lighting compensation system  100  in accordance with a first embodiment of the present subject matter. In particular, life cycle lighting compensation system  100  is provided with a controller  102  that receives input signals from multiple sources by way of feedback networks  104 . These input signals generally correspond to operational signals derived from driver  112 , lighting device  114 , and optical sensor  116  conveyed to controller  102  by way of signal lines  122 ,  124 ,  126 , respectively, feedback networks  104  and representative signal line  128  that may correspond to plural signal lines. 
         [0025]    Signals transferred over line  122  from driver  112  to feedback networks  104  may correspond to such as drive current level, drive voltage level, type of drive signal including, for example, the general shape or other characteristics of the drive signal, that is, whether the drive signal is pulsed, triangular, sinusoidal, constant voltage, constant current, or of other form or characteristic. Signals transferred via line  124  from lighting device  114  may indicate, without limitation, such as, the total amount of time the device has operated, the temperature of the device, or other properties associated with the operation of the lighting device  114 . 
         [0026]    It should be appreciated at this point that while the present disclosure speaks generally of a controller  102  as receiving signals from and providing signals to various components, such is not a specific limitation of the present subject matter. Those of ordinary skill in the art will readily appreciate that other devices including, without limitation, application specific integrated circuits (ASIC), micro-processors, micro-controllers, general purpose computers, and other such devices may equally well be employed to implement the present subject matter. 
         [0027]    Regardless of the particular hardware and/or software chosen to implement any particular embodiment of the present subject matter, the result would be an appliance lighting system that provides lighting at its highest visual quality during all operational conditions of the appliance. 
         [0028]    A system constructed in accordance with the present technology is designed to monitor the lifetime lighting conditions of an appliance and to drive the lighting system higher or lower accordingly. For example, a discrete LED lighting system may be found to have a half life of five (5) years with LED brightness decreasing linearly over that time. Such a lighting system may be started by driving the LED using a pulse width modulation (PWM) scheme with a 25% duty cycle in the early life of the LED. By the time the LED is at half life, the duty cycle may be increased to 50% to accommodate and give the visual appearance of consistent LED lighting, that is, not a dim LED, that may be visually un-appealing or may be mismatched relative to other nearby LEDs that may be less frequently used. 
         [0029]    In accordance with present technology, there a number of options that may be chosen to compensate for light source lifetime interactions. One option, as illustrated in  FIG. 1 , is to monitor reference light from a reference LED  118  as it impinges on optical sensor  116 . Alternatively or in addition, the driving conditions of the lighting system may be monitored throughout the lifetime of the lighting device. For example, the driving conditions from driver  112  of lighting device  114  may be monitored via signals lines  122 ,  124  and feedback networks  104  to track how much lighting systems are used and at what power. In this instance, lighting device  114  that provides the displayed light may correspond to one or more similar light emitting device where one of the devices may correspond to a reference light source  118  whose light output is representative of that of the entire lighting device  114 . Alternatively, reference light source  118  may correspond to the display light itself. 
         [0030]    With reference now to  FIG. 2 , there is schematically illustrated an ambient lighting compensation system  200  in accordance with a further embodiment of the present technology. As will be appreciated by those of ordinary skill in the art, lighting schemes will generally appear differently in different ambient lighting conditions. Under such conditions lighting device  214  will be adjusted by the controller  202  through driver  212  to compensate for sensed ambient light  218  as transmitted to the controller  202  by optical sensor  216  and feedback network  204 . 
         [0031]    In an exemplary arrangement, an LED screen or 7-segment displays would be driven differently in darkness than in bright conditions when they could be driven at less power and still be visible without harshness to the eyes. Similar diverse driving requirements would be necessary for fluorescent lighting, incandescent lights, LED&#39;s, and other types of light emitting devices etc. 
         [0032]    With reference to  FIG. 3 , there is schematically illustrated a light sensor  300  for providing a light level signal to a controller. Light sensor  300  may correspond to a photo diode  316  coupled to an adjustable gain amplifier  304 . Photo diode  316  is configured to receive light from a light source  318  while signals generated by photo diode  316  are amplified by adjustable gain amplifier  304  and sent as an input signal to a controller. With reference to  FIGS. 1 and 2 , it will be seen that light sensor  300  may correspond to either or both optical sensor  116  and or optical sensor  216 , responding to either ambient light as in system  200  of  FIG. 2  or light from a reference light source as in system  100  of  FIG. 1 . 
         [0033]    Given the above disclosure regarding systems  100  and  200 , it should be further appreciated that features of the two systems may be combined to further enhance the consistency of long term lighting obtainable through use of the present technology. 
         [0034]    Referring to  FIG. 4  there is illustrated an exemplary stove  400  including among other well recognized features, a display panel  410  that may generally include lighting device such as lighting devices  114  and  214  whose lighting consistence over the lifetime of the lighting device is to be monitored and controlled. It should, of course, be appreciated that the present subject matter is not limited to lighting device employed in stoves, but rather may be used in any appliance wherein lighting device may be provided. 
         [0035]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.