Author Topic: Public Domain Design for a Low Cost Braille Terminal  (Read 12819 times)

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Offline happyrat1

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Re: Public Domain Design for a Low Cost Braille Terminal
« Reply #25 on: September 21, 2014, 05:41:38 am »
BTW, it occurs to me that the spring latching design lends itself easily to multiline displays.  Just add a Y Axis stepper to the printhead and you are capable of hammering out a page at a time with a simple mechanical lever arrangement for the refresh. :D

Gary
« Last Edit: September 21, 2014, 05:50:38 am by happyrat1 »
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Offline int2str

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Re: Public Domain Design for a Low Cost Braille Terminal
« Reply #26 on: October 31, 2014, 06:22:40 am »
How about this:
(Assuming each character is 2x4=8 pins)
Use two tiny stepper drivers and 4 pins mounted to a camshaft that covers all 16 possible positions for the 4 pins. For a row of 40 characters you'd need 80 stepper motors, but you can reset a full line very quickly and probably more quietly than using solenoids (even just 3).
 

Offline happyrat1

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Re: Public Domain Design for a Low Cost Braille Terminal
« Reply #27 on: October 31, 2014, 06:36:15 am »
Just off the top of my head I'm thinking too expensive a design.  Not only the cost of manufacture and assembly of the Cam design but also the cost and implementation of 80 stepper motors. (Brrrr!) 

So far I think Dave's design is the overall winner for cost effectiveness for something that could be mass produced for under $150.

Btw I'm curious, has anyone else out there made any progress implementing any of these designs?

If there was ever a product design which truly needed to be produced, then this is the one.

Gary
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Offline Richard Crowley

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Re: Public Domain Design for a Low Cost Braille Terminal
« Reply #28 on: October 31, 2014, 06:36:24 am »
The Braille grid is 2 columns by 6  3 rows (a fact easily confirmed by a Google search of a few milliseconds).
Using a large number of stepping motors (and the necessary mechanical translation) is infinitely more complex than even using the same number of solenoids.
Since Braille is binary, not linear, there are only two possibilities, UP or DOWN.  You don't need stepper motors for that.  happyrat1 was trying to SIMPLIFY the mechanism.

I think happyrat1 has a brilliant idea, borrowing the concept of the old dot-matrix printers to push the pins up, using a simple mechanical "latch", and then a mechanical "reset".

EDIT:  happyrat1 corrected my typo about the number of rows.  Thanks!
« Last Edit: October 31, 2014, 06:53:21 am by Richard Crowley »
 

Offline int2str

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Re: Public Domain Design for a Low Cost Braille Terminal
« Reply #29 on: October 31, 2014, 06:37:34 am »
Nevermind actually, your design is a really good idea.
You need only 2 stepper motors total or 1 stepper motor and 1 servo.

The basic setup would be a single axis "carrier" driven by the stepper motor (lead screw or sled/belt setup) and the servo or stepper motor on the carrier driving a 16 position camshaft. As the carrier moves left/right, the cam rotates into the appropriate positions to push the pins up.

To reset, the stepper motor can drive the carrier back to the left and push the spring loaded reset plane over to the left to reset all pins.

Super low cost and drive-able by a dirt cheap microcontroller.
 

Offline int2str

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Re: Public Domain Design for a Low Cost Braille Terminal
« Reply #30 on: October 31, 2014, 06:38:47 am »
The Braille grid is 2 columns by 6 rows (a fact easily confirmed by a Google search of a few milliseconds).

See:
 

Offline happyrat1

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Re: Public Domain Design for a Low Cost Braille Terminal
« Reply #31 on: October 31, 2014, 06:41:36 am »
The Braille grid is 2 columns by 6 rows (a fact easily confirmed by a Google search of a few milliseconds).


The matrix for standard Braille is actually 2X3 pins.  Bit of a brain freeze there Richard? ;)

Actually though, I've also seen reference to some kind of superset of Braille using 2X4 matrix.  Don't ask me for a citation right now though :)

Gary
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Offline happyrat1

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Re: Public Domain Design for a Low Cost Braille Terminal
« Reply #32 on: October 31, 2014, 06:53:09 am »

The basic setup would be a single axis "carrier" driven by the stepper motor (lead screw or sled/belt setup) and the servo or stepper motor on the carrier driving a 16 position camshaft. As the carrier moves left/right, the cam rotates into the appropriate positions to push the pins up.


I still can't see what value the camshaft adds to the design.  A simple servo (a la dot matrix printhead) accomplishes the exact same thing without the need of adding an extra mechanical component and additional cost to the mechanism.

Exactly what purpose would the camshaft serve other than to act as an intermediary between the printhead and the pins?

Gary

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Offline int2str

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Re: Public Domain Design for a Low Cost Braille Terminal
« Reply #33 on: October 31, 2014, 07:43:54 am »
A simple camshaft design can replace the 3 (4) solenoids per pin row.
It's not complex at all and can be dragged by the bottom of the pins to push them up easily.

Less complex, less noise, less I/O pins required on the controller etc.
 

Offline happyrat1

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Re: Public Domain Design for a Low Cost Braille Terminal
« Reply #34 on: October 31, 2014, 07:47:00 am »
There's only 3 or 4 solenoids in the ENTIRE design.

The head moves along the track firing each column 3 pins at a time.

How does adding a mechanical cam assembly improve that in any way?

Gary
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Offline int2str

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Re: Public Domain Design for a Low Cost Braille Terminal
« Reply #35 on: October 31, 2014, 08:15:43 am »
Understood. You're pushing the 3 pins up with 1 solenoid each.
The cam can push all 3 (any combination of them) up, with only a simple stepper motor, or even better, tiny hobby servo. Also solves the problem of packing the solenoids or solenoid linkages into a small enough package. The cam can be molded/3d printed in any size.

So instead of doing it with 2 steppers + 3 solenoids as was initially proposed, I'm saying it can be done with 2 steppers total or 1 stepper + 1 micro servo.

Noise wise instead of hitting each row of pins from the bottom with a solenoid, you have to only rotate the cam slightly as you drag it along the bottom of the pins.

Quick drawing of a 3 pin cam is attached.
 

Offline Richard Crowley

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Re: Public Domain Design for a Low Cost Braille Terminal
« Reply #36 on: October 31, 2014, 08:19:35 am »
Understood. You're pushing the 3 pins up with 1 solenoid each.
The cam can push all 3 (any combination of them) up, with only a simple stepper motor, or even better, tiny hobby servo. Also solves the problem of packing the solenoids or solenoid linkages into a small enough package. The cam can be molded/3d printed in any size.

So instead of doing it with 2 steppers + 3 solenoids as was initially proposed, I'm saying it can be done with 2 steppers total or 1 stepper + 1 micro servo.

Noise wise instead of hitting each row of pins from the bottom with a solenoid, you have to only rotate the cam slightly as you drag it along the bottom of the pins.

Quick drawing of a 3 pin cam is attached.
That is rather clever, also.  Something more akin to using "daisy-wheel" printer technology vs. dot-matrix.
Turn a cam (or whatever) to the proper place to push up the right combination of pins and activate the column(s) with a single stroke.
 

Offline happyrat1

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Re: Public Domain Design for a Low Cost Braille Terminal
« Reply #37 on: October 31, 2014, 02:35:39 pm »
Actually as the thread progressed we eliminated one stepper for the locking tines when the spring locking plate was introduced to the design.

At the current phase of the design we are down to 1 stepper, 3 or 4 solenoids and a mechanical lever assembly for refresh.

One thing that nags me about the cam design is whether or not it is slower or faster than the solenoid design.  Furthermore, using a stepper or servo to drive the cam would require periodic recalibrations (perhaps as many as one per column) to ensure the cam is firing on the correct setting every time.  All of this takes time and creates additional noise, further slowing down each output line.

Also I seriously doubt if it would be any, if at all, quieter than the solenoid design with all that mechanical manipulation for each column.

The amount of power required, if at all less, would be negligible with either design I'd think.

Lastly, dot matrix printheads have been around for three decades now and the technology for building a 3x1 or 4x1 solenoid printhead is pretty much cut and dried.  In this application the job is even easier since the printhead of the Braille terminal would actually be built on a slightly larger scale than your average pica type character matrix.

All this, particularly the constant recalibration of the cam servo to maintain alignment makes your idea simply less attractive and more costly to implement than my simple dot matrix inspired design.

Sorry, but then again I have opened the floor to innovation on this project and released the material to public domain for anyone to pursue as they will.  If you are sold on your cam idea then more power to you in building it, though to me it seems more complex requiring more complicated software to implement than my simple dot matrix design.

Anyone out there who is following this thread is permitted to use my original design in any way they see fit in order to design and build prototypes as well as working production models, hopefully with minimal red tape or delay.

So if you can sell a manufacturer on your cam idea then more power to you brother.  :-+

Just as long as street price can be kept below $150 or the price of a medium grade Android tablet.

Gary
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Offline happyrat1

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Re: Public Domain Design for a Low Cost Braille Terminal
« Reply #38 on: October 31, 2014, 02:44:54 pm »
To add the final nail to the coffin I just realized a total dealbreaker with the cam design.

As it cycles thru the combinations it will accidentally push random pins up into the locked position on EVERY SINGLE CYCLE.

In effect it will leave every single pin in an ON state everytime it cycles unless it is rotated first below the pin level and THEN fired upward by a solenoid on each column. 

That will make it a hell of a lot larger in vertical dimension and a hell of a lot noisier and more power hungry and slower having to fire up the mass of the entire cam assembly including stepper for each and every column.

Pardon me for playing devil's advocate here, but I'd have to say that this is not a better mousetrap.

Gary ;)
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Offline happyrat1

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Re: Public Domain Design for a Low Cost Braille Terminal
« Reply #39 on: October 31, 2014, 02:51:58 pm »
Incidentally this video appeared in my inbox the other day describing a new technology that allows tactile response in mid air over a touchscreen utilizing ultrasonic vibrations.



Not sure whether or not it could apply to a Braille terminal but it does look promising.

Gary
« Last Edit: October 31, 2014, 02:55:53 pm by happyrat1 »
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Offline int2str

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Re: Public Domain Design for a Low Cost Braille Terminal
« Reply #40 on: November 01, 2014, 05:51:23 am »
At the current phase of the design we are down to 1 stepper, 3 or 4 solenoids and a mechanical lever assembly for refresh.

I'm suggesting a 1 stepper, 1 micro servo setup that covers everything (including reset).

Quote
Furthermore, using a stepper or servo to drive the cam would require periodic recalibrations (perhaps as many as one per column) to ensure the cam is firing on the correct setting every time.  All of this takes time and creates additional noise, further slowing down each output line.

A servo would not require resetting. An end switch for a stepper would also be simple.

Quote
Also I seriously doubt if it would be any, if at all, quieter than the solenoid design with all that mechanical manipulation for each column.

As far as noise goes, a microservo & dragging against the pins vs. solenoids hammering at the pins. I'll leave that up to your imagination.

Quote
Lastly, dot matrix printheads have been around for three decades now and the technology for building a 3x1 or 4x1 solenoid printhead is pretty much cut and dried.  In this application the job is even easier since the printhead of the Braille terminal would actually be built on a slightly larger scale than your average pica type character matrix.

I must have misunderstood. I thought your aim was to come up with a simple design that can be produced on a small scale and is extremely affordable. A custom printhead is neither easy to design nor to manufacture. Nor would it be cheap in small quantities. Even solenoids themselfs aren't cheap, nor available off the shelf in small enough dimensions to make this work.

The mechanical design for the pin locking/resetting you came up with is genious. It can easily be 3d printed or otherwise produced in small quantities. Why not use an actuating mechanism that can use off the shelf parts (like a micro servo) and easily 3D printable/moldable parts that will be cheap even in small quantities?

Quote
All this, particularly the constant recalibration of the cam servo to maintain alignment makes your idea simply less attractive and more costly to implement than my simple dot matrix inspired design.

I'm not sure how you can say a dot matrix design is simple. Especially in small quantities.
And again, a servo does not need re-calibration.

Quote
it seems more complex requiring more complicated software to implement than my simple dot matrix design.

Still not seeing the "simple" dot matrix design.

Quote
As it cycles thru the combinations it will accidentally push random pins up into the locked position on EVERY SINGLE CYCLE.

In effect it will leave every single pin in an ON state everytime it cycles unless it is rotated first below the pin level and THEN fired upward by a solenoid on each column. 

That will make it a hell of a lot larger in vertical dimension and a hell of a lot noisier and more power hungry and slower having to fire up the mass of the entire cam assembly including stepper for each and every column.

This is a complete misunderstanding of the mechanism.
The cam as pictured has 8 positions from "0" (no pins raised) to "7" (all pins raised). As you swipe left->right, it rotates between alignments to set the next row of pins.
 

Offline happyrat1

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Re: Public Domain Design for a Low Cost Braille Terminal
« Reply #41 on: November 01, 2014, 07:50:50 am »
I think the main misunderstanding here is that you are thinking about a cottage industry home brew device.

My intention in releasing the design is to interest major manufacturers in producing these units for the mass market and by removing IP concerns lower the costs associated with mass production.

Personally I'll stick by my dot matrix impact design as the simpler and more economical and reliable design to promote over the rotating cam design.

Hopefully any manufacturer who expresses interest in developing either will test both designs and choose the more efficient of the two for the final mass market version.

It remains my hope that these units can be effectively mass marketed with a street price under $200 in order to make the technology more accessible to all, including the third world.  Current technologies cost more for an 80 character display than a recent model used car.

I'm hoping we can change that for the better here.

Either way, I'm thankful for your interest in this worthwhile and necessary project.

Gary
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Offline happyrat1

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Re: Public Domain Design for a Low Cost Braille Terminal
« Reply #42 on: September 30, 2015, 07:34:35 am »
It's been about a year since I've last revisited this thread.

My father's illness and subsequent passing this spring as well as the demands of tying up loose ends this summer have kept me from pursuing this project any further.

A request on another forum by the father of yet another blind musician led me back here again to inquire as to whether or not anyone has put any of this discussion to good use so far and if so are there any viable projects popping up on the near horizon?

There is some stuff on this website that looks promising

http://www.nbp.org/ic/nbp/technology/braillepda.html

but they are sketchy on details of both price and operational design being as they are still in pre-release beta and there are IP and investor concerns obfuscating the release of these details.

Anyway, would love to hear about anything else out there that anyone has found so far.

Gary ;)

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Offline happyrat1

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Re: Public Domain Design for a Low Cost Braille Terminal
« Reply #43 on: July 20, 2017, 08:01:59 am »
Well it's been yet another two years since I've last revisited this thread and I'm EXTREMELY pleased to announce that someone has indeed followed us up on this thread and put a terminal into product that shaves about 90% of the price tag off of a Braille Terminal!!!!

A company named Orbit Research announced last winter that they are contracted to put into production 50,000 units of the Orbit Braille Reader 20 at the mind blowing MSRP of about $320  a pop!

http://www.orbitresearch.com/product/tactile-products/orbit-reader-20/






Give yourselves a well deserved pat on the back ladies and gentlemen.

We have, with this humble thread, created a force for good in this world :)

I'm going to break out my cappuccino machine in celebration and enjoy this little bit of news with relish :D

Gary ;)
« Last Edit: July 20, 2017, 08:34:06 am by happyrat1 »
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