The seat heater of the present invention comprises: a warming heater provided in a seat section of a seat; a warming heater provided in a back section; an overheating-prevention unit; and a heating unit that heats the overheating-prevention unit, the overheating-prevention unit being configured by a non-return type temperature switch. This configuration allows activating the non-return type overheating-prevention unit prior to reaching an unsafe event, and turns the warming heaters OFF reliably, whereby a seat heater with an aim of implementing both high output and safety can be provided.
1. A seat heater for use in a seat having a seat section and a back section, comprising:
a first warming heater that warms the seat section of a seat;
a second warming heater that warms the back section of the seat;
a single overheating-prevention unit that prevents overheating of the first warming heater and the second warming heater;
a heating unit that heats the single overheating-prevention unit;
a parallel circuit that connects the first warming heater and the second warming heater in parallel with each other, and having a branch point; and
wherein the single overheating-prevention unit comprises both a return type overheating-prevention unit and a non-return type temperature switch, wherein the non-return type temperature switch is heated by the heating unit and the non-return type temperature switch having an activation temperature higher than the return type overheating-prevention unit, and the single overheating-prevention unit is connected to the parallel circuit via the branch point of the parallel circuit;
the heating unit includes:
a first heating heater installed in the seat section, and electrically connected to the first warming heater, and
a second heating heater installed in the back section, and electrically connected to the second warming heater,
the second heating heater having a caloric value higher than that of the first heating heater.
2. The seat heater according to claim 1 , wherein the overheating-prevention unit has a mechanical part which is mechanically secured to the seat.