Affordable Wheel Based Refreshable Braille Display • Hacker News Board

Re: Affordable Wheel Based Refreshable Braille Display

#51

Post by jodrellblank » Sat, Mar 16, 2024, 7:08 PM UTC

contingencies wrote: post #50

jodrellblank wrote: post #23

Tiny pinpoint holes, blow air through them. Could you adjust the size of the holes and the flow of the air so you could feel them distinctly? If so, they could be backed by much larger, far away, valves without the mechanical parts needing to be so fine and precise. You only need to feel something, there doesn't need to be anything there - is it possible to have a voltage or capacitance charge or signal at a point wh…

Yes, you can do that but you still need a cheap valve with a size ideally smaller than one dowel pin 'cell' at standard braille densities. AFAIK this does not exist commercially, if it does it would be cost prohibitive, and therefore would need to be designed in some unknown manner focused on low fabrication cost. Since most valves operate based upon electromagnetism (solenoid-driven) you also have an electrical cont…

The reason for suggesting that is because it wouldn't need tiny expensive custom delicate valves; connect the pinhole to a funnel which gets wider like the horns on this siren: https://stall.net/victorysiren/photo-pages/cars2/images/5SG-...

then you can use whatever large, cheap, widely spaced, easy to access, easy to maintain, valves you can find. The trade would be size, noise, and power, but the gain would be easy to build, mass produced parts, easy to repair, large and solid and relatively reliable.

Re: Affordable Wheel Based Refreshable Braille Display

#52

Post by mzs » Sat, Mar 16, 2024, 7:13 PM UTC

It seems something like the media produced from am embossed labeler or stylus could work. Dot matrix printer head could be a good starting point. If the medium was vinyl like it possibly could be reused by feeding it through warm rollers to the print head.

Re: Affordable Wheel Based Refreshable Braille Display

#53

Post by contingencies » Sat, Mar 16, 2024, 7:16 PM UTC

jodrellblank wrote: post #51

contingencies wrote: post #50

Earlier quoted context omitted.

Yes, you can do that but you still need a cheap valve with a size ideally smaller than one dowel pin 'cell' at standard braille densities. AFAIK this does not exist commercially, if it does it would be cost prohibitive, and therefore would need to be designed in some unknown manner focused on low fabrication cost. Since most valves operate based upon electromagnetism (solenoid-driven) you also have an electrical cont…

The reason for suggesting that is because it wouldn't need tiny expensive custom delicate valves; connect the pinhole to a funnel which gets wider like the horns on this siren: https://stall.net/victorysiren/photo-pages/cars2/images/5SG-... then you can use whatever large, cheap, widely spaced, easy to access, easy to maintain, valves you can find. The trade would be size, noise, and power, but the gain would be easy…

Most valves are actuated by solenoids which use a lot of power. An array of them is not only physically huge but will exceed USB power availability at a count of one or two valves and you need many per braille block. Worse, you generally need to actuate huge numbers of them simultaneously. This approach is therefore difficult to consider for a real world deployment.

Re: Affordable Wheel Based Refreshable Braille Display

#54

Post by contingencies » Sat, Mar 16, 2024, 7:34 PM UTC

sitkack wrote: post #46

I think PCB based designs will have a better Design for Mass Manufacturability. See the work of Carl Bugeja. https://www.youtube.com/watch?v=oa6sP-joAr8 Either motors, or solenoids, electromechanical brakes, compliant mechanisms.

This is the approach I used for my prototype (thanks to Carl!) and it does function.

However, since the area is quite "edge case" (rarely developed in public), there remain challenges in balancing the electrical and control requirements with physical requirements, electromagnetic density, part selection, manufacturing process and cost.

Re: Affordable Wheel Based Refreshable Braille Display

#55

Post by itronitron » Sat, Mar 16, 2024, 7:34 PM UTC

I think an alternative approach would be to have some sort of woven fabric loop that can have raised braille dots stitched into it from the right side and then the loop is pulled to the left. So it would read like one of those scrolling LED banners except it would be a fabric belt with raised dots.

Maybe the simplest approach mechanically would be to have Nitinol wires running vertically, parallel to the 'weft' thread. To print a single letter in Braille would require stamping two Nitinol wires to render the raised dots in the correct positions, and then feeding the fabric belt to the left. On the return side, hidden underneath the display, the Nitinol wires could be returned to their original state.

Alternatively, any technique that could raise a knot in the fabric which could then be easily released would be worth pursuing. That could be as simple as something that pushes a loop up (for a braille dot) through the fabric belt and then pulls it back out on the return trip.

Re: Affordable Wheel Based Refreshable Braille Display

#56

Post by contingencies » Sat, Mar 16, 2024, 9:47 PM UTC

cyanfrog wrote: post #24

woudn't grid of electromagnets work for this? spring loaded pin that gets retracted by the magnet?

Commercially available electromagnets are too bulky, require too much power and are designed with generally physically unworkable assumptions around electrical interface types with respect to cost-effective manufacturing. In short the principle is sound, but the products are unworkable. Therefore, the coils must be integrated on-PCB to be cost effective.

Re: Affordable Wheel Based Refreshable Braille Display

#57

Post by mNovak » Sat, Mar 16, 2024, 9:58 PM UTC

I wonder if the tiny unipolar motor in a quartz watch would have enough torque to spin a small half-character wheel. Those things are dirt cheap, and thin, so you could realistically drive each cell independently.

Re: Affordable Wheel Based Refreshable Braille Display

#58

Post by atoav » Sat, Mar 16, 2024, 10:28 PM UTC

ta988 wrote: post #35

atoav wrote: post #17

Earlier quoted context omitted.

Why not just use mechanically decoupled pins that vibrate with a smartphone vibration motor? You don't need texture if the thing vibrates.

Cost and noise would make that extremely unpractical.

As opposed to the low cost texture changing material proposed?

If I had to do this I'd probably look into PCB-based solenoids with compliant mechanisms. But there are already people working on that.

Re: Affordable Wheel Based Refreshable Braille Display

#59

Post by AndrewKemendo » Sat, Mar 16, 2024, 10:46 PM UTC

j-a-a-p wrote: post #8

Beautiful example of the innovation narrative that keeps CTOs of the largest companies awake at night. A (very) intelligent outsider, with pen and paper, computer, a 3D printer who lives where Aliexpress delivers. Meanders and bounces between theory, practice and sleep deprivation can come up with a disruptive PoC in a matter of weeks [0]. I would really like this to work, and/or that it inspires others to make these…

Not just any old guy but my good friend and our very own Jacques

https://news.ycombinator.com/user?id=jacquesm

Re: Affordable Wheel Based Refreshable Braille Display

#60

Post by jodrellblank » Sat, Mar 16, 2024, 11:09 PM UTC

contingencies wrote: post #53

jodrellblank wrote: post #51

Earlier quoted context omitted.

The reason for suggesting that is because it wouldn't need tiny expensive custom delicate valves; connect the pinhole to a funnel which gets wider like the horns on this siren: https://stall.net/victorysiren/photo-pages/cars2/images/5SG-... then you can use whatever large, cheap, widely spaced, easy to access, easy to maintain, valves you can find. The trade would be size, noise, and power, but the gain would be easy…

Most valves are actuated by solenoids which use a lot of power. An array of them is not only physically huge but will exceed USB power availability at a count of one or two valves and you need many per braille block. Worse, you generally need to actuate huge numbers of them simultaneously. This approach is therefore difficult to consider for a real world deployment.

The top comment on this thread by gostsamo is "As someone blind, my two pens [pence?] are that noise, power consumption, and fragility are things that could be compromised to a large degree."

How many do you consider 'huge numbers'? There's another comment saying a Braille cell is 8 dots, and if you average changing half of the dots each time to change state, you could barely get into double digits to keep ahead of the fingers.

> "This approach is therefore difficult to consider for a real world deployment."

It only had 10 seconds of thought; I just skim read the article which was all about mechanical actuation and the difficulty of making so many small and precise and reliable actuators cheaply enough, and wondered about options that didn't require that part. Air, electric current (e.g. the vibration felt in a pot on an induction hob vibrating some loose rods without having to actually lift them), or a one-finger glove where there is only a few actuators and they change as the finger slides over a table, or no actuators - a design like the way a CRT screen has a scanning electron beam activating each pixel, although I have no ideas how a design like that could activate Braille dots.