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MOLBED Modular Low cost Braille Electronic Display

A project that I started in 2014, aimed to develop a low cost and modular refreshable Braille system

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The goal of this project is to create an electronic Braille system that is affordable and can make this technology available to everyone. After initial evaluation, it was clear that thus the design of the individual character had to meet some minimum requirements:
• must use as many parts that are already commercially available
• should be made up with the lowest parts count possible
• custom parts must be easy to prototype, easy to scale up (injection molding)
• power must be not needed to keep the state of the pins
After working on several iterations, I have designed an electronic Braille character with a magnetic retaining system that has a really low parts count, is easy to reproduce or to scale up for production!
The project was self-funded, and I decided to not patent this system because I'd like to see as many people as possible benefit from it. The support of Italian association for people with impaired vision will be very important!

Project video:

This image shows the development of the project, from the beginning to the current status of development.

The main idea behind the project is quite simple: For each pin, one coil can move move some very small magnets from one end of a cylindrical body; at each end, two small pieces of ferromagnetic material will hold the pin in position. With this design, power is not needed to keep the state of the pins.

I have successfully tested the pin mechanism, and built some character modules; of course the project is still work in progress and the final size and performances can be greatly optimized.

Now the development has been organized in phases.

  1. In the first one, a Maker friendly, breadboard compatible Braille character will be developed. An Arduino demo shield will be developed to test the system and showcase the project.
  2. When the character system will be refined enough, a “LinePCB” will be designed, and will hold 8-10 characters, with a modular approach. A “PagePCB” will then be designed, and will hold 6-8 lines.
  3. Finally, an entire Braille refreshable screen will be developed, and it may be used for a standalone device like a Braille Tablet, or incorporated into an existing device.

How does it work?

With the current design, each "dot" on a character module is made up of 2 3D printed parts (Body and Magnet holder), 2 M2 nuts, 2 magnets, and 0.1mm enameled wire. A controlling PCB also hold the bodies. This design uses a really low parts count, and efforts have been put to use parts already available, such as the M2 steel nut; this design allows for a very low cost per character.

A (not definitive) cost analysis

The cost for a single pin , for a production in the order of hundreds, is estimated around or less then 0.85€. It includes nuts, 2 injection molded parts (magnet holder and body), magnets, and coil.

The cost for a single character is thus in the order of 5/6€ per character, with a small/medium sized production.

The cost for an entire line of 10 characters is around 120€, including 60€ of characters and 60€ of pcb, most of it due to the TB6612 currently used which are quite expensive.

An hypothetical device with 8 lines, a controlling board, sensors, battery and enclosure should have a total cost of less than 1000€ for a medium/small production, allowing a final retail price of probably 2000€... which is quite not bad compared to the commercial products available today!

BrailleSystemComplete.zip

This is the concept of the Braille Tablet I am going to develop (should funding or winning the Hackaday Prize happen!). Zip files contains the full Solidworks assembly. Requires Solidworks 2015.

x-zip-compressed - 19.01 MB - 10/11/2016 at 08:39

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BraillePrinterSystem.zip

This is the project for the portable Braille Printer that I am designing. When completed, it should be integrated in the docking station of the Braille Tablet. Zip files contains the full Solidworks assembly. Requires Solidworks 2015.

x-zip-compressed - 20.64 MB - 10/11/2016 at 08:30

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BrailleChar3.zip

This is the PCB for one character, Zip files already used for production of the PCB (Gerber, drills, etc).

x-zip-compressed - 11.10 kB - 10/11/2016 at 07:59

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Test_DemoBoard_Uno_Oled_FILMS.ino

This is a sample Arduino program. It will show letters "F I L M S" as shown in the video. Requires an Arduino Uno Board and the "Arduino Shield with Oled" PCB.

ino - 13.43 kB - 10/11/2016 at 07:51

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ArduinoShieldWithOled.zip

This is the latest version of the demo board for testing characters. It is designed as an Arduino shield for Arduino Uno. Zip files already used for production of the PCB (Gerber, drills, etc).

octet-stream - 63.07 kB - 09/30/2016 at 14:21

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  • 2 × M2 Steel Nut An M2 steel nut is used as an easy to get, low cost part for the holding mechanism
  • 2 × 2mm dia, 2mm tall magnet They are inserted into the Magnet holder
  • 1 × Magnet holder (3d printed) Magnet holder is available to download as STL file
  • 1 × Body (3d printed) Body is available to download as STL file
  • 1 × Coil (0.1mm enameled wire) 5.5m are used, approx 300 turns

  • MOLBED being tested and lots of feedback!

    Madaeon10/13/2016 at 16:55 1 comment

    Today during a meeting with an association for blind people in Italy, MOLBED has been tested and we received a lot of feedback, that will be very important for developing a product that is tailored to their needs.

    This is a short list of their suggestions / requirements:

    -Multi line is not important as we might think; a standard size Braille cell dimension, on the other hand, is more desired to get faster read speed. The MOLBED character can be re-configured to take the same, or slightly longer space, but have the same pin size and distance as standard (expensive) Braille cells;

    -Integrating a Braille paper printer on the docking station may be very interesting;

    -Chances of funding for this kind of projects will probably be much difficult for the current "state of things", at least in this country, despite they recognize that this project really has a lot of potential.

    So at the moment the Hackaday Prize is still the best opportunity for this project to be continued and give this people a low cost alternative to expensive products, and that can be really tailored on their needs!

  • Concepts for Braille Tablet with docking station and printer

    Madaeon10/11/2016 at 08:49 0 comments

    Both are available for download as Solidworks assembly. The printer is quite refined and with some refining is ready for prototyping.

    Winning the Hackaday Prize would be super! Up to now all the project was self-funded and it has been a quite time-consuming project, so some funding may be necessary for this project to be continued...

    Concept design for the final Braille Tablet with docking station:

    Concept design for Braille Printer (that will be integrated into the docking station):

  • A lot of things

    Madaeon09/30/2016 at 15:20 0 comments

    The testing characters are now working well; finding the perfect balance is still under progress, and a lot of optimization of the pins can be done. I have redesigned the character PCB, with smaller pads for easier soldering of the enameled copper wires.

    I have made 3 different testing boards, designed as Arduino Uno Shields, for easy testing of the characters. Two of them have a small embedded Oled display for showing the corresponding letter and debugging. I even designed a 3d modeled cover for it ;)

    In the meanwhile, I wanted to try different materials. Have the 3d printed parts made in castable resin and casted them in brass, the look is certainly more professional!

    And a character made with the new black Character PCB and these parts:

  • Testing BrailleShield demo board

    Madaeon09/22/2016 at 15:16 0 comments

    In order to be able to quickly test the Braille character units, I designed a demo board, that should be also useful to showcase the project to potential users.

    This board is designed as an Arduino shield, 12v powered, using 3 TB6612 ICs to drive the coils.

    It has a button to select the showing modes, and the space for a 128x64 Oled that will display the letter that corresponds to the Braille letter shown by the pins.

    Eagle design files are available.

  • Refining the single character

    Madaeon09/11/2016 at 10:12 0 comments

    I received the new PCBs for the single character; I also built an automatic coil winder to speed up the process, even if the design of the coil still needs improvements; Actually the pin mechanism is more similar to a coil gun than to a standard electromagnet, since we have a coil and the magnetic "bullet" travelling inside; the placement and number of turns of the coil is the most critical part.

  • Improving the design

    Madaeon08/01/2016 at 15:16 0 comments

    Now that the single pin and the character have proven to work, I am focusing on the electronic design.

    The character PCB has to connect the 6/8 coils with the connector that plugs into the line PCB.

    The line PCB will control through H-bridges the coils, and (it's no begin tested) it would be very useful if it can also sense when a pin in pressed down, so the module can be used to "write" too.

    In the meanwhile, the quest for the best optimization of the single pin leads to testing of a different design!

    In this design the got an even lower part count: every Pin has just 3 3d-printed / injection moulding parts, and two Flexinol wires, and still can offer a bi-stable behaviour and power is needed only to change state. The Flexinol wire (you can find some technical info here) is used as an actuator. Around 10cm of wire is used for the "up" movement and the same amount for the opposite direction. Assuming a 4-5% amount of shrinkage when activated, it should provide 4-5mm of movement that should result in 2-2.5mm travel distance of the pin. The wire is wrapped around the moving part in order to keep the Pin small, with enough wire to get at least 2mm of travel.

    Currently I am 3D printing the body and the front/back halves.

  • First character testing - It works!

    Madaeon07/23/2016 at 10:10 2 comments

    In this test we spell in Braille h-a-c-k-a-d-a-y (correctly, I hope :) It works, finally!

    Lot of things still to be improved, coil optimization for faster refresh and state change, smaller overall size, higher holding force, design the PCB for the line control. Each pin has just one coil driven by H-bridges, that will be integrated in the line PCB.

    Interesting thing is that the cost for a single character will be very low, since this project is designed with the goal to use parts as common as possible and as cheap as possible.

    Each character consist in a pcb, connectors to the Line PCB, the body and magnet holder and top plate (injection molded if the project will raise some funds), 2 M2 nuts an 2 magnets and some enameled copper wire.

    It is almost impossible to get an even lower part count!

    The next steps will be optimization of the single char and designing of the character / line PCB. An automatic coil winder is already being designed, and I am also evaluating to build a micro-factory where the pins are automatically assembled, more on this in the next updates!

    Feedback are also important, we are now getting in contact with Italian associations for visually impaired people, their feedback will help refining the project.

    When the design will be refined enough, I'm going to design a full Braille tablet, and it may feature 2G connection via a Fona module, color recognition, eBook reading, maybe a modular design too...

  • Testing and assembling the first character

    Madaeon07/19/2016 at 10:27 0 comments

    Testing the first character. At the moment an Arduino and 3 L293 are used to control the coils- h-bridges, each pin has a single coil. The key of this system is the magnetic interaction between the magnets that are free to move inside the pin and the retaining M2 nuts at each end. Power is used only to change from a state to the other one. The distance between the magnets and the nuts is quite important for a correct behaviour.

  • Testing and assembling the pins for the first character test

    Madaeon07/12/2016 at 14:04 0 comments

    Testing and assembling the pins for the first character test.

  • Designing the Line PCBs

    Madaeon06/30/2016 at 16:42 0 comments

    I am now designing the Line PCB, where you can stack 8 /10 characters, with integrated multiplexed control.

View all 17 project logs

  • 1

    3D Printing the body and magnet holder

    The body and magnet holder file are available in STL file format and can be printed with a resin-based 3D Printer. Part thickness is down to 0.3mm in some points, but it still printable, and after UV curing the part is strong enough.

  • 2

    Assembling the magnet holder

    Once you have 3D printed the parts, it is necessary to assemble them. This video shows how the different components of one pin are assembled for the current prototype.

  • 3

    Coil winding

    I assembled a simple machine to automate the coil winding. It is controlled by an Arduino.

View all 4 instructions

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Discussions

Martin wrote 07/19/2016 at 11:11 point

You could save half bridges in the driver, if you do some mulitplexing. Like connect all "A" ends of the coils of one character to one half bridge and the "B" ends to individual half bridges. 7 half bridges per character (6 pins) instead of 12.

Full multiplexing is difficult as you can not use decoupling diodes because you have to drive the coils in both polarities.

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Trevor Johansen Aase wrote 07/11/2016 at 02:01 point

Fantastic progress! I think you may have the simplest version I have ever seen. Also great idea on the machine nut retaining mechanism to avoid the "Clicky Pen Patent". I await a demo video of a completed digit.

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Madaeon wrote 08/01/2016 at 15:27 point

Thanks! By the way, the demo of the complete character is available as a video!

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