What's this small, "free coil" over a pin component?

[mcinque]

I found this in a Xytronic soldering iron stylus.

The central pin was connected to one side of the thermocouple.
The free coil was connected to a wire connected to the electronic board.

The coil isn't connected to the central pin.
Did you ever seen this kind of component?

What is it for? Some kind of capacitive sensing?

[Alex Eisenhut]

It would also probably pick up vibrations or acceleration, such as movement... The spring would contact the inner pin.

[Benta]

Movement sensor. When the iron is in its holder, it switches to stand by power. As soon as you pick it up, it goes to the preset power/temperature.

Not really a power saving feature, but it prevents the tips from oxidising too much.

[mcinque]

It would also probably pick up vibrations or acceleration, such as movement... The spring would contact the inner pin.

Movement sensor. When the iron is in its holder, it switches to stand by power. As soon as you pick it up, it goes to the preset power/temperature.
Not really a power saving feature, but it prevents the tips from oxidising too much.

You are right. If not moved for a while, the soldering iron lowers the tip temperature to 100°C.

Thanks! I never saw that kind of component.