3 ms·

I will preface this by saying that i never built anything related to this, nor am i visually-impaired so take whatever i say with a grain of salt. However i hav

I will preface this by saying that i never built anything related to this, nor am i visually-impaired so take whatever i say with a grain of salt. However i have been interested in the subject on & off for quite sometime following some hype around Braille tablets a decade ago. (which sadly never materialized) > 30 units of display thingy They are usually called "Braille Cells" (sometimes called "piezoelectric braille cell") and have 8 dots (instead of the usual 6 for books) [https://en.wikipedia.org/wiki/Computer_Braille_Code https://en.wikipedia.org/wiki/Computer_Braille_Code] These cells are comprised of 8 levers. The "Dot" rises when a voltage is applied to a crystal that expands due to the piezo effect/bimorph. Here is a video of someone taking apart a couple of them and showing the insides, driver etc.. https://www.youtube.com/watch?v=TmwFsTLkpa8 https://www.youtube.com/watch?v=TmwFsTLkpa8 (it's not an in-depth look but just to get an idea) You can read about how it works in more details here : https://cdn.intechopen.com/pdfs/9307/InTech-Analysis_and_design_of_piezoelectric_Braille_display.pdf https://cdn.intechopen.com/pdfs/9307/InTech-Analysis_and_des... Okay now what? Well you could acquire some from ebay like this one i guess https://www.ebay.com/itm/255908240759?hash=item3b9551dd77 https://www.ebay.com/itm/255908240759?hash=item3b9551dd77 Or try to find something from Metec, i have seen their P20 as well as the B11 Module used with arduino projects several times, here is the website https://metec-ag.de/en/produkte-braille-module.php https://metec-ag.de/en/produkte-braille-module.php They also sell "Braille Lines" which are combos : cells + backpanel/driver : https://metec-ag.de/en/produkte-braille-zeilen.php https://metec-ag.de/en/produkte-braille-zeilen.php (If you find a way to buy them i would greatly appreciate you sharing it) PS : These cells use 200V DC to work so your project will need a DC-DC converter. You can search for similar speccs to the official one on aliexpress or whatever https://metec-ag.de/downloads/dcdc-converter-5to200v.pdf https://metec-ag.de/downloads/dcdc-converter-5to200v.pdf Finally you would need a brain for all this which could be the raspi directly or you might opt for using the raspberry-pi (for the ebook manipulation, character-to-dot conversion etc.. unless you decide to pre-format the files) in conjunction with an arduino (for the signal transfer/propagation.. you know sending the dot configuration) Take a look here for some software inspiration (it also explains the signals the braille module would be expecting but you are better off looking at the Datasheet for anything serious): https://github.com/bertrandmartel/metec-braille-driver#more-resources https://github.com/bertrandmartel/metec-braille-driver#more-... Good luck. ---- Some more resources : A nice video from "Applied Science" about a one Cell driver DIY project (He is i believe, using the P16 cell from metec) might help you decide whether to buy a backplane-driver or make your own [also the idea of putting a push-button underneath the braille-cell might be interesting to you for a selection mechanism maybe?] : https://www.youtube.com/watch?v=Ss-Fux86doQ https://www.youtube.com/watch?v=Ss-Fux86doQ A video showing Metic P20 cells + backpanel + DC step-up converter driven by an Arduino Uno (it has no value other than to hopefully encourage you to pursue this project :D ) https://www.youtube.com/watch?v=3zqth08wQBs https://www.youtube.com/watch?v=3zqth08wQBs Designing Braille System using P20 Braille Cells Presentation (a student project i think with a good overview of the minimum necessary parts and their functions you can skip to the 5min mark to avoid the usual academia-fluff) https://www.youtube.com/watch?v=rAYB0g6LhVM https://www.youtube.com/watch?v=rAYB0g6LhVM

bramd 3y ago
Braille tablets/multiline braille displays are finally coming. The traditional piezo-electric cells are not well suited for them, due to the space the cell + driver+ electronics need. Putting the four rows of pins in a cell does already require staggering the elements. If you disassemble a cell, you'll see that every row has another pin length the bottom row usually has the longest and the top row the shortest pins. So this is not very scalable for multiple lines of dots. There are two commercially produced techniques for multiline braille displays now: the first comes from Dot (a Korean company) who makes the Dotpad, this technique is also used in the Humanware/APH Monarch which will be an Android based standalone braille tablet. The other technique is created by Orbit Braille and they have their Graphity braille tablet. I couldn't find any good technical documentation that describe how these methods work exactly, so if anyone has any pointers I would like to read more about it.

bramd 3y ago

Braille tablets/multiline braille displays are finally coming. The traditional piezo-electric cells are not well suited for them, due to the space the cell + driver+ electronics need. Putting the four rows of pins in a cell does already require staggering the elements. If you disassemble a cell, you'll see that every row has another pin length the bottom row usually has the longest and the top row the shortest pins. So this is not very scalable for multiple lines of dots. There are two commercially produced techniques for multiline braille displays now: the first comes from Dot (a Korean company) who makes the Dotpad, this technique is also used in the Humanware/APH Monarch which will be an Android based standalone braille tablet. The other technique is created by Orbit Braille and they have their Graphity braille tablet. I couldn't find any good technical documentation that describe how these methods work exactly, so if anyone has any pointers I would like to read more about it.