Electromechanical Refreshable Braille Display

Lowering the cost of refreshable braille Cells down from 100$ to 10$ by using electromagnetic cam actuators

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The most significant drawback to refreshable braille devices has always been their cost. From the mid-1980s to the present, the loose rule of estimation applied to these products has translated into something like $100 to $150 per braille cell. A 40-cell display, in other words, may cost $4,000 to $6,000, while an 80-cell model will cost $8,000 to $12,000. And so it has been that, while desirable, braille computer access has been out of reach for many users of assistive technology.

It is thus of great value to lower the cost of individual braille cells in order to manufacture Refreshable Braille Devices at a price that is affordable to the Visually Impared community.

Commercially available braille displays use expensive piezo-electric actuated pins. This project employs an electromechanical system with off-the-shelf and easily manufacturable components to keep the cost low without compromising functionality.

Design & Engineering Goals:

  • < 10$ price of each Braille Cell
  • <1W Power consumption 
  • Standard Braille sizing 
  • Scalable to multi-row braille Display
  • Ease of Manufacturing & Assembly
  • 8 Dot Braille

Prior Work:

This design in principle works like a previous design using cam actuation, by replacing the vibration motor with a solenoid that causes an eccentric cam that is embedded with a rare-earth magnet to rotate, and in turn, lift a braille pin. 

Refer to the Project logs for a full table of references.

Working Principle: 

An electromechanical, electromagnet-based braille display that can represent braille characters. The key principle is a cam actuator, consisting of an eccentric cam that has a rare-earth magnet embedded into it which is rotated to two stable positions by the action of an electromagnetic that changes its polarity. The rotation of the eccentric cam causes a braille dot to be lifted up or taken down.

The cam rotates slightly more than 180° and is stopped against the wall of the enclosure (Upper Cell). Once the Braille pin is lifted, the weight of a finger on the pin(while reading braille) cannot back drive the cam. This not only satisfies the need for protrusion force of the braille pin but also that the electromagnet need not be powered once the pin has been lifted resulting in lower power consumption.


Prototyping is done using a high-resolution SLA 3D Printer as there are many thin-walled sections.
PR4 REsin on a 3D Systems Figure4 machine is being used for its ability to achieve 0.2mm wall thickness.

To meet the cost goals of the project, the braille cells will be injection molded in POM after the validation stage. The design has already been optimized for injection molding.

The micro 1mm x 0.5mm NdFeB magnet is what makes this project possible, and would be impossible without the availability of such tiny magnets. Luckily there are now a handful of vendors around the world keeping these in stock as they are also used for things like jewelry clasps on thin bracelets, Kingdom Death miniatures, super thing Games Workshop miniatures, and more.

The electromagnets will be constructed with 40-micron enamel-insulated copper wire with a soft iron core. A winding jig will be created to help wind the could around lengths on 0.6mm Soft Iron wire.


The electronic circuit will be heavily inspired by the workings of Flip-Dot displays. Instead of discrete drivers for each braille cell, the same driver will actuate pins of a full braille display with multiple braille cells using a multiplexer since a braille pin doesn't need to be kept powered on once actuated.

Failure mode and mitigation: 

The biggest problem expected with the design would be the interaction of all the magnets in a single braille cell with each other, which would prevent the braille cell from functioning appropriately.

To mitigate against this:

  • The magnet power could be varied (with controlled heating?)
  •  Thin steel sheets could be introduced in between the cavities of the "Upper Cell" to shield against the magnetic fields of the individual magnets
  • Using plastic material during the 3D Printing or Injection molding process that contains iron particles that would dampen the magnetic field of the magnets.
  • Using Metal Injection Molding(MIM) to produce the "Upper Cell". 
  • Electroplating a thin layer of NIckel (which is ferromagnetic) over the "Upper Cell"

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  • 1st 3D Printed Prototypes

    Vijay05/28/2023 at 07:28 0 comments

    Hey there, Hackaday community! I wanted to share an exciting update on my ongoing project focused on 3D printing small Braille parts. Today, I want to discuss the significance of resolution when it comes to creating high-quality Braille tactile components.

    One of the most critical factors in creating functional Braille parts is achieving a high level of detail and precision. In the case of 3D printing, resolution plays a pivotal role in determining the readability and usability of Braille tactile elements.

    To begin, let's dive into what resolution means in the context of 3D printing. Resolution refers to the level of detail that can be captured and reproduced in a printed object. It is typically measured in terms of layer height or the minimum feature size that the printer can accurately produce.

    When it comes to the required Braille parts, which rely on tiny tactile dots, cams, and an enclosure with small wall thickness, achieving a high resolution is essential. The components need to be precisely formed and accurately positioned to ensure legibility and functionality. Increasing the resolution can create more defined dots with sharper edges and smoother surfaces, resulting in enhanced touch sensitivity.

    The smallest wall thicknesses needed for a functional prototype were 0.4mm. After exploring and evaluating a wide range of options for 3D printing, I settled on SLA technology with the 3D Systems Figure 4, which offered the best resolution among all the printers tested. I chose to print with the PR4 resin, they gave the best results for toughness and yet a touch of flexibility that was needed for some of the snap-fit components. 

    The parts came out great, but it was quite a struggle to assemble the parts together. Got me to understand the design changes that would be needed to make this easier to assemble, without needing to be a watchmaker.

    Design for Assembly and Manufacturability will be a big part of the design changes going forward.

    I'll continue my exploration in this project, experimenting with different printers, materials, and techniques to further enhance the resolution quality and assembly of 3D printed Braille parts. Stay tuned for more updates! Feel free to share your thoughts, suggestions, or any experiences you've had with micro-scale 3D printing projects. Let's collaborate and make a difference together!

  • References & Previous Work

    Vijay05/20/2023 at 04:54 0 comments

    This project is derived from years of work and research done by scientists and engineers over there years and is in no way "novel". Indigenous production of refreshable braille devices is essential to have this technology accessible to visually impaired communities in all countries without relying on imports and duties on already expensive devices. My goal in working on Braille Displays is not only to create a working device but to do so in a way in which it can be indigenously produced without needing a complex supply chain and assembly process.

    I started working on refreshable braille displays almost 10 years ago when I was introduced to the problem statement by professors from the MIT Media Lab.

    in 2016 after talking to Paul D'Souza and learning about his amazing braille projects, I started working on a refreshable braille display design derived from his idea to use micro-vibration motors.

    Chris Ulbi, doing his Masters's Thesis at the time took the design further to create a working prototype 

    The current design is inspired by the work of Joonyeong Kim et al.: "Braille Display for Portable Device Using Flip-Latch Structured Electromagnetic Actuator"

    The design was changed with the intention to have all parts 3D Printable and overcoming some of the challenges in the design:

    • Interference of magnets with each other.
    • A drive system adapted from Flip Dot displays to keep the electronics low cost and improve the refresh rate.
    • Prevent the action of gravity causing the pins to fall out when used in other orientations.
    • Redesign coil and coiling procedure to lower the cost of the electromagnet.

    Other References:

    MOLBED 2 project, and the manufacturing processes used for winding the coils.

    Paul D'Sousa and his work

    M. Benali-Khoudja, M. Hafez, and A. Kheddar, “VITAL: An electromagnetic integrated tactile display,” Displays, vol. 28, no. 3, pp. 133–144, 2007.

    F. S. Cooper, "Research on reading machines for the blind" in Blindness Modern Approaches to the Unseen Environment, N. J., Princeton:Princeton University Press, pp. 512-543, 1950

    H. Freiberger and E. F. Murphy, "Reading machines for the blind", IRE Trans. on Human Factors in Electronics, vol. HFE-2, pp. 8-19, March 1961.

    Mohamed Benali-Khoudja, Moustapha Hafez, Jean-Marc Alexandre, and Abderrahmane Kheddar "Tactile interfaces: a state-of-the-art survey" SR 2004, 35th International Symposium on Robotics, 23-26 March, Paris France

    M. Benali-Khoudja "Electromagnetically driven high-density tactile interface based on a multi-layer approach" November 2003 DOI:10.1109/MHS.2003.1249924 IEEE Xplore

    T. Völkel, G. Weber, and U. Baumann, “Tactile graphics revised: The novel BrailleDis 9000 pin-matrix device with multitouch input,” in In International Conference on Computers for Handicapped Persons, 2008,

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