Why do some HP calculators have springs inside?

[lvt]

Hi all,

I wonder why some HP calculators (landscape models) have small springs inside.

It may sound strange, but I have opened my HP 12C Platinum once, took a quick look to the PCB (I'm curious about what kind of chip my HP 12C has) then put it back together, and I didn't pay attention to those springs. In fact, I don't even know that the springs exist until I watches some videos on Youtube.

Are those springs functional? What happens if one is missing?

Thanks.