How instax printer works?

Never quite able to figure out how Instax printer works...don't see any sensor, or something that lights the film. I see that resolution is 600x800 pixels, many reviews and how to...but explanation of how this actually works - I cannot find.

Thanks

My Instax mini Share printer has OLEDs to expose the print . I have no idea how it functions internally. Prints are beautiful. I send the direct from my X PRO 3, or from my phone using Nikon Snap bridge. It's a marvelous little machine.

That's the same printer I have.

Yes, much better results than from Instax mini camera itself. Too bad that there is no Instax wide printer out there.