Smoke and vapor detector for microwave oven

A detector adapted to detect the presence of particles of smoke and water vapour, in the chamber of a microwave oven during a heating procedure, said detector comprising a transmitter designed to transmit electromagnetic radiation of an optical nature and arranged in a compartment which is shielded from external radiation and which, during a heating procedure, is filled with air from the oven chamber;

• first and second receivers in said compartment filled with said air from the oven chamber;
• said first receiver arranged opposite to the transmitter and designed to receive direct radiation from the transmitter along a transmission path through the interior of the compartment;
• said second receiver shielded from direct radiation from the transmitter and designed to receive indirect or scattered radiation from the interior of the compartment, each receiver emitting an output signal that is a measure of the radiation received, the output signal from said first receiver changing in opposite direction to the output signal from said second receiver;
• and a signal-processing circuit which is connected to the receivers and in which the output signals therefrom are compared to indicate, upon a given change of the relative magnitude of the output signals, the presence in the chamber air of particles affecting the radiation transmission.