braille switch matrix

There are products that enable blind people to communicate with a computer. See for instance  http://www.tiresias.org/research/devices/braille_displays.htm This way a blind person can control a computer controlled switch matrix. It might be necessary to make changes to the control software.

Hello, there must be some unit based on 6 solenoids that are controlled by external logic. May be that those units are difficult to find, but i've seen them used as "display" in a telephone set for visually impaired people. For a VERY limited number of characters, you can try to build one by yourself, using 6 microrelays for each digit and some rigid wire to couple the moving part of the relay to the tactile "dot", in order to create the appropriate Braille patterns. That's a very complicate solution ... Better if you find the commercial parts.

Ciao

Not entirely sure what you mean by switch matrix. My initial thoughts are that you're referring to a keypad like this:

If that is the case, many keypads of this nature have a 'pip' on the 5 which is used by people with visual impairment to navigate the keypad.

OOPS ! After reading the post of Mr. Ellison, I realized that my previous answer might be absolutely out-of-topic... I interpreted "Braille switch matrix" as the output unit (display) based on 6 solenoids that generates the tactile dots pattern that can be read from blind people. If you are looking for INPUT device, then you can try this way: realize a "tactile switches" matrix on a pcb (tactile switches are cheap and with long operating life). Apply a plastic (or metal) mask over the switches matrix, with a hole of about 10mm diameter centered on every tactile switch. This plate must be placed at right distance from the PCB. In practice, the top of tactile switch pin must be at 0.1 - 0.2 mm distance from the surface of the plastic-metal plate. Now, cover the plate with adhesive mylar sheet, with embossed pattern for each Braille character you want, each placed at the center of a tactile switch (and the 10 mm plate hole). Et voilà, you have your keyboard.

To emboss the mylar, you can use a CNC machine with the right tool for this purpose (pressure or temperature can be used to create the bubbles) and a proper program. On my blog at this url: http://ficara.altervista.org/?p=1508 you can find an example of a program (very old, compiled with 16 bit Windows tool) to generate a G-Code for a dot matrix punch/drill operation on CNC machine. Changing the internal "character generator" from actual 5x7 dots to 2x3 dots (Braille), it's possible to realize the embossed mylar sheet. Hope to be "in-topic" this time