How does the Logitech MX Keys proximity sensor work

[SouthGate]

Just a curiosity question. If I place my hand 1" above the MX keys with no contact the back light comes on, same if covered by an A4 sheet but just a smidge closer. I can't find anything on it Google. I presume it's detecting eletrical charges?

Edited October 11, 2020 by Broughton

[adrynalyne]

  On 11/10/2020 at 01:26, Broughton said:

Just a curiosity question. If I place my hand 1" above the MX keys with no contact the back light comes on, same if covered by an A4 sheet but just a smidge closer. I can't find anything on it Google. I presume it's detecting eletrical charges?

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Most likely an IR proximity sensor. 

[iamdavid01]

The first sensor which is the proximity sensor that uses a attractive field to turn on the backdrop illumination when your fingers close the keys, then, at that point turn it off when you pull away. The second is an ambient light sensor, which changes the splendor to coordinate with the lighting in the room. In this manner it works.