Ricoh Thermopiles

[Jinn]

Hi Experts,

I am a new Ricoh tech. I wanted to know the theory of Ricoh Fuser units. How the parts of Fuser unit works.

I am working on 3 and 4 series these days and I am wondering what is the function of two thermopiles facing the Fuser unit?

[slimslob]

The termopile is a non contact temperature sensor. They serve to read the Center and End (front) temperatures of the fusing sleeve. They are used to determine which of the lamps in the fusing unit need to be ON.

[Jinn]

The termopile is a non contact temperature sensor. They serve to read the Center and End (front) temperatures of the fusing sleeve. They are used to determine which of the lamps in the fusing unit need to be ON.

Thermopiles are non contact temperature sensors when there are already two non contact thermistors are installed inside the fuser unit. These thermopiles are not in the fuser unit. They are inside the fuser seating area. I am wondering what is the purpose of installing these 4 sensors here. Thermopiles and thermistors.

Which sensors detects high temperature and cuts off the lamps?

[Gift]

The ones inside the fuser are called thermostat but actuatlly they are just a fuse using a bimetal plate to cut off the power. There are (usually) also thermistors checking the press roller but I think the surface of the fuser sleeve is too delicate so they are using non-contact thermistors there.