Status indicating light unit and aircraft comprising the same

#This application claims priority to European Patent Application No. 14 162 214.2 filed Mar. 28, 2014, the entire contents of which is incorporated herein by reference.

#The invention relates to lighting systems, such as used in passenger transport vehicles, such as aircraft, road vehicles, ships or rail cars. In particular, the invention relates to light units that indicate their operational status to their power supply.

#LED light units are becoming more and more common in many fields of technology. In the exemplary field of passenger transport vehicles, such as aircraft, road vehicles, ships or rail cars, more and more interior and exterior lights are based on LED technology. Such LED light units are commonly designed for a particular power consumption and, accordingly, for a particular power reception from the power supply. However, this power reception may not always be stationary over time. In particular, if one of the LEDs breaks, a situation may arise where the LED light unit becomes defective and does not collect any power from the power supply. It is also possible that the power consumption of the LED light unit increases over time in order to provide more current to the LEDs in order to keep the output light intensity constant despite ageing of the LEDs. These changes in the functioning of the LED light unit are an important piece of information for the overall passenger transport vehicle. In particular, this information would be useful to have for a maintenance computer of the passenger transport vehicle, such as an aircraft maintenance computer or car maintenance computer. In prior art approaches, no satisfactory system for conveying said information has been proposed.

#Embodiments of the invention are described in greater detail below with reference to the figures, wherein:

#FIG. 1 shows a circuit diagram of an exemplary embodiment of a status indicating light unit in accordance with the invention.

#FIG. 2A-2C show three exemplary power transfer patterns between an exemplary power supply and the exemplary embodiment of the status indicating light unit of FIG. 1 over time.

#FIG. 1 shows a circuit diagram of a status indicating light unit 2 in accordance with an exemplary embodiment of the invention. The circuit diagram of FIG. 1 shows circuit components only. Mechanical components, such as a mounting plate, e.g. a printed circuit board, a housing, and a lens cover are omitted for a clearer representation of the circuit structure.

#The status indicating light unit 2 has two external terminals, namely a power input terminal 4 and a ground terminal 4a. The power input terminal 4 is coupleable to an external power supply, i.e. to a power supply that is outside of the status indicating light unit 2. The ground terminal 4a may also be connected to the external power supply, in particular to a ground terminal thereof. It may also be coupled to a commonly available ground rail, as is present throughout many passenger transport vehicles at various locations thereof.

#The power input terminal 4 is coupled to a mode selection switch 30. The mode selection switch 30 has one input, to which the power input terminal 4 is coupled, and two outputs. The mode selection switch 30 is configured to selectively couple the power terminal input 4 to one of the two outputs. In other words, the mode selection switch is configured to couple the power input terminal 4 to one of the two outputs at any given point in time.