Fragrance diffuser having stepped power levels

Abstract

A fragrance diffuser (100) comprises a housing defining a chamber (116) for holding a fragrance-emitting block (110), a heating element (112) located within the housing, a timing and indicating circuit board (114) to signal when the predicted life of the fragrance emitting block has expired, a power supply connection plug (134) for providing electrical power to the heating element and the timing and indicating board, and a keying system (234, 236, 238) incorporated in the chamber (116) and on the fragrance-emitting blocks (110). The blocks are encoded or keyed to indicate that they possess particular predefined characteristics, such that only blocks having those characteristics may be inserted. The diffuser is constructed with a downwardly-projecting housing extension (132) for the power supply connection to allow the use of an adjacent electric power outlet when the diffuser is properly installed. The diffuser also includes an indicator LED (156) to indicate when a timing interval, corresponding to the life of a fragrance block inserted therein, has expired, wherein the timing interval is reset by a switch (182) only at the request of a user. Various circuit embodiments are disclosed for increasing the power applied to the heating element over time, since the aroma strength of a fragrance block decreases over time.