I wanted a flipcover for my phone, and i wanted to make it myself. And then it struck me that i might as well add a keyboard to it.
Ok i admit that the keyboard is by far the hardest part, but still, it would be really cool to have.
The keyboard part gives a few obvious chalenges. For intsance, how does one make the keys. Usually this is done with a domesheet, with all those fancy rubber domes. This is not really doable here, because it would be too thick for a flipcover.
This is why I had to inovate a revolutionary new way of keyboardmaking. And, as with everything, the solution was... Magnets.
I presume that this requires some explaining. If you think about it, all you need to make for a keyboard is a switch. And then you only have to copy paste that a couple of times. (If only copypaste worked in real life.)
To make a switch, you a someting to make contanct, and something, that makes sure that this contact doesn't make contact all the time. In this case, the contact is a magnet. Magnets are made of metal, so they work quite well as contacts. What keeps the contact from making contact all the time, is also a magnet. This magnet is at the bottom side of the pcb, and repels the magnet on the top. To make sure the magnet on the top does not slide sideways, it is kept in place by the textile on the inside of the flipcover.
Et voila, a magnetic keyboard.
I have tested this principle on a small hand-etched pcb, and it works with a led. There is a bit of noise, so i will have to filter this in software.
One sideeffect of this design is that you have a big magnet on the your phone. This is usefull to stick your phone to the roof of your car or something. It might however also throw off the internal compass of the phone.