A seat heater includes a seating heater, a protection device of a non-resettable type, a base material, and a protecting heater. The protection device has a first surface and a second surface opposite to the first surface. The base material is a sheet having a first covering portion covering the first surface and a second covering portion covering the second surface, and is folded so that the first covering portion and the second covering portion face each other. The protecting heater heats the protection device. The protecting heater includes a pair of first heating portions and a second heating portion. The pair of first heating portions are formed as a meandered shape only on a surface, which faces the second covering portion, of the first covering portion. The second heating portion is disposed between the pair of first heating portions, and formed as a meandered shape both on the surface, which faces the second covering portion, of the first covering portion, and on a surface, which faces the first covering portion, of the second covering portion.
1. A seat heater to be used together with a seat, the seat heater comprising:
a seating heater connected to a power supply in order to heat the seat;
a protection device which has a first surface and a second surface opposite to the first surface, the protection device being configured to disconnect a connection between the seating heater and the power supply when a temperature of the protection device rises to a predetermined temperature;
a base material, which is sheet shape, having a first covering portion covering the first surface and a second covering portion covering the second surface, the base material being folded so that the first covering portion and the second covering portion face each other; and
a protecting heater configured to heat the protection device, the protecting heater including:
a pair of first heating portions formed as a meandered shape only on a surface, which faces the second covering portion, of the first covering portion, and
a second heating portion disposed between the pair of first heating portions, the second heating portion being formed as a meandered shape both on the surface, which faces the second covering portion, of the first covering portion and on a surface, which faces the first covering portion, of the second covering portion.
2. The seat heater according to claim 1 , wherein:
the seat includes a seating portion and a back portion,
the seating heater includes a seating portion heater used together with the seating portion, a back portion heater used together with the back portion, and a connecting point disposed between the seating heater and the power supply, the connecting point electrically connecting the seating portion heater and the back portion heater, and
the seating portion heater and the back portion heater are electrically connected in parallel, and the protection device is disposed between the connecting point and the power supply.
3. The seat heater according to claim 2 , wherein:
the protecting heater includes a first protecting heater electrically connected in series to the seating portion heater, and a second protecting heater electrically connected in series to the back portion heater, and
the protection device is heated by the first protecting heater and the second protecting heater.
4. The seat heater according to claim 3 , wherein an amount of heat to be generated by the second protecting heater is greater than an amount of heat to be generated by the first protecting heater.
5. The seat heater according to claim 1 , wherein:
the seat includes a seating portion and a back portion,
the seating heater includes a seating portion heater used together with the seating portion and a back portion heater used together with the back portion,
the protecting heater includes a first protecting heater and a second protecting heater,
the protection device includes a first protection device and a second protection device,
the seating portion heater and the back portion heater are electrically connected in parallel,
the seating portion heater, the first protecting heater, and the first protection device are electrically connected in series,
the back portion heater, the second protecting heater, and the second protection device are electrically connected in series,
the first protection device is heated by the first protecting heater, and
the second protection device is heated by the second protecting heater.
6. The seat heater according to claim 1 , wherein the protection device is not automatically resettable.
7. The seat heater according to claim 1 , wherein the protection device is a thermal fuse.
8. The seat heater according to claim 1 , wherein the protection device is manually resettable.
9. The seat heater according to claim 1 , wherein the protection device is resettable upon lowering of the temperature of the protection device.
10. The seat heater according to claim 1 , wherein the protection device does not automatically reconnect the connection between the seating heater and the power supply.
11. The seat heater according to claim 1 , wherein the protection device is one of a thermal fuse, a manually resettable thermostat, or a thermostat that does not automatically reset in a normal environment.