This disclosure relates generally to home appliances, and, more particularly, to methods and apparatus to determine home appliance cabinet temperatures using light emitting diodes (LEDs).
Many home appliances utilize thermistors to determine home appliance cabinet temperatures. Such thermistors measure temperature at only one place in a cabinet and require the use of a separate wiring harness.
Methods and apparatus to determine home appliance cabinet temperatures using LEDs are disclosed. An example home appliance includes a cabinet, a lighting system disposed in the cabinet having one or more LEDs to provide lighting in the interior of the cabinet, and a circuit electrically coupled to the lighting system and programmed to determine a temperature inside the cabinet based on a characteristic of the one or more LEDs of the lighting system.
An example method of determining a temperature inside a cabinet of a home appliance, the method includes activating a lighting system disposed in the cabinet having one or more LEDs, measuring a characteristic of the one or more LEDs while the lighting system is activated, and determining the temperature inside the cabinet based on the measured characteristic.
While not shown in
While the example refrigerator 100 shown in
Referring to
To measure the voltage VD across the lighting system 205, the example circuit 200 of
To determine an ambient temperature in which the lighting system 205 is operating (that is, the temperature inside a home appliance cabinet), the example circuit 200 of
where I is the amount of current output the current source 210, IS is the reverse bias current or saturation current of the diodes 215, VD is the voltage across the LEDs 215, VT is the thermal voltage of the LEDs 215, n is the ideality factor, which is also known as the quality factor of sometimes the emissions coefficient, and N is the number of diodes 215. Knowing I and VD, the processor 225 can use the equation above to solve for the voltage VT which can be used to lookup the temperature in which the diodes 215 are operating.
To convert the voltage Vo to a digital value that may be processed by the processor 225, the example processor 225 of
Because the diodes 215 are distributed through a home appliance cabinet, the voltage VT represents an average of the temperature at each of the diode locations. Thus the methods and apparatus disclosed herein give a more accurate home appliance cabinet temperature than a single thermistor, which may suffer from a localized temperature variation. Moreover, instead of requiring a separate wiring harness to read values from a thermistor, the example circuit 200 of
Referring to
To translate the voltage Vo into a temperature, the example circuit 300 of
Although certain example methods, apparatus and articles of manufacture have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the claims of this patent.
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