What is this component (probably a shock/vibration sensor) ?

[neoply]

Hello all. Thanks for taking up your time to read my post.

The other day I received a promotional wrist band from a convention booth -- it has two LEDs that flash when you jostle it. I removed the guts to see how it works.

Most of this is pretty straight-forward: LEDs, a SOT-23 transistor, some passives -- no uC that I can see (on top, at least) -- but I'm interested in the metal can in the middle, with the refdes K1. I assume this is the sensor that detects when the device has been tapped or shaken. It's a metal cylinder with two leads, and on the inside there is a smaller metal cylinder -- it might be a coil or spring, but it's hard to tell.

Does anybody know what this component is called and how it works? Maybe the spring moves when shaken, changing the capacitance or inductance. Whatever it is, it must be cheap (this is a give-away promotional item). It would also be nice, I imagine, if the mechanical energy it collects is enough to wake-up the rest of the device so that it could have a no-power sleep state.

Note, too the shiny metal pad under the near end of the can, perhaps a ground needed for the operation of the device. It looks like there is some clearance between the can and the pad (and the rest of the pcb, for that matter).

UPDATE: Based on the feedback, it's probably a vibration-induced trigger switch, something like D7E-1 as the datasheet of http://www.kynix.com/uploadfiles/pdf0125/D7E-1.pdf , that is, just a spring in a tube that makes contact with the case when it moves.

Can anyone help me ? I am very puzzled about this question. I do need your help.

thanks in advance

[Ttelmah]

This has been asked before in other places:

<https://electronics.stackexchange.com/questions/105826/what-is-this-component-probably-a-shock-vibration-sensor>

There are three basic technologies for these simple sensors:

1) Mercury - still used, but with lots of regulations now.
2) Small ball bearing and contacts.
3) Spring.

For the latter, look at the one shown here:

<https://dmohankumar.wordpress.com/2016/08/08/anti-bag-snatching-alarm-start-up-project-26/>

It sounds like this might be the sensor involved, especially since this is the cheapest:

<http://www.addicore.com/SW-18020P-Standard-Sensitivity-Vibration-Sensor-p/167.htm>

[neoply]

Thanks for your answers. Your answer would be useful to me. I want to listen to others' ideas. Do you have better ideas ? Thanks a lot.