[Arm-netbook] Future case idea: subnotebook/PDA with QWERTY keyboard

[Joseph Honold]

On 09/04/2016 11:16 AM, Sam Pablo Kuper wrote:
> It might be naive of me, but my impression is that the hardest part of
> making a housing like this is probably getting the keyboard right. So
> many moving parts; such critical layout, tactility, and reliability
> requirements.
> 
> I figure there are two broad satisfactory options:
> 
> (1) Design and build keyboards using commonly available push-switches,
> combined with PCBs and housings made from designs released as Free
> Cultural Works.[0]

My idea is to use snap domes attached to a sticker and placed directly on the pcb which has exposed copper pads for contacts (keyboard matrix). The sticker could be laser (or hand) cut to any shape and snap domes hand placed (for prototype). The snap dome method is how most phones (and Zipit Z2, see my post https://mozzwald.com/articles/zipit-soft-keypad-mod) do it these days. The snap domes are available and I actually got a sample kit from Snaptron (http://www.snaptron.com). There are some far east manufacturers of snap domes also.

The difficult part (IMO) is creating the rubber/silicone overlay. A prototype could be made by either 3D printing a mold and casting a silicone keypad, or just 3D print the keys in plastic (or some other preferably soft material). Both these methods should work but I don't expect backlight to work well if at all (need translucent material). The labeling of keys might be difficult to achieve with 3d printng.

Before I found out about EOMA68 I was intending to make a raspi handheld using this keypad layout https://mozzwald.com/public/images/misc/keypad.png

Are there any preferred keypad layouts?