How to invert the function of the Fn key on a keyboard?

[Kahenraz]

I bought a brand new wireless keyboard which I happen to like. However, it has inverted all of the function keys (F1, F2, F3, etc) so that I have to press the "Fn" key to use them.

Is there a small circuit that I can make to invert the behavior of this key such that it is always active until I press it? I can confirm through testing that this does not appear to cause a problem with any of the other keys.

I am a electronics hobbyist and can build small circuits as necessary. But I'm still inexperienced at how to modify things to create certain behavior.

This is a membrane type of keyboard (it's very thin) so I would expect that I would have to use an x-acto knife to shave off some of the plastic to get to the trace and then use a very thin wire and a steady hand to solder anything to this, hopefully without it breaking or melting. I won't know if it will work until I try!

Here is the keyboard I ordered:

https://www.amazon.com/gp/product/B075SY8XRM

[Fergo]

You can usually change this behavior by pressing FN+Esc on most keyboards. It will toggle between regular mode or "FN always on".

[Kahenraz]

Well, HEY! I tried that and it turned on a little light at the top with a "Fn" inside the picture of a lock. It's actually a feature.

Thank you!

I'm still interested in the circuit as an exercise all the same.

[ledtester]

I'm still interested in the circuit as an exercise all the same.

Computer keyboards are implemented as a switch matrix which is scanned by sort some of digital logic - a microcontroller, keyboard controller, etc. It would be very difficult to modify the switch matrix or insert some circuitry between the switch matrix and keyboard controller to modify its behavior. In fact, it would probably be easier to replace the entire keyboard controller.

Here's a video which explains how keyboards are scanned: