Hi all
I joined the forum just to get feedback on an idea that might make it a lot quicker and easier to build custom mechanical keyboards. (I'm not into keyboards per se, but I would like to get an ergodox or similar at a reasonable price, hence my recent interest).
Anyhow, the idea is to use a simple pcb overlay held against a capacitive touchpad to register key presses. The pcb would be a simple array of copper circles, each connected to one of the keyboard switches. The other side of all the switches would be connected to (eg) some mass of copper, like an unetched pcb, to ensure a large change of capacitance with each keypress. Some quick experiments with the Apple magic touchpad and the FingerMgmt utility suggest to me that these touchpads are responsive enough, and have a high enough resolution, that the idea could work.
Of course driver software would be required to translate the key presses to characters.
The advantages of this approach (if it works) would include:
Simpler construction - no diodes, a single wire from each key back to the overlay.
No microcontroller, and no cables if you use a bluetooth touchpad.
No need to wire any particular key to any particular pad on the overlay, as a training sequence would be necessary in any case to register each key with the driver software.
If this much works ok, it might even be possible to design the overlay in such a way that the trackpad could still be used as a normal trackpad, by building a thin, stick-on overlay from eg Pyralux, dividing each pad into sectors, and using separate pcb tracks to each sector to ensure that there was not a gross loss of resolution for finger gestures.
What do you think? It may have already been tried, as I said Im not an enthusiast per se.