Actuation Mechanism for Braille Display Devices

• Over 60 million people globally are either blind or severely vision-impaired.

• India alone has over 7 million vision-impaired individuals, with 2 million blind children, many of whom are illiterate.

• The demand for improved, affordable Braille devices is crucial to addressing literacy challenges among the visually impaired.

The Braille Dot Movement Device developed by me and my colleague (Aayush Bhansali from IIT Madi) uses a compliant mechanism. This approach reduces the number of moving parts to just two, simplifying the device’s structure and enhancing its performance.  The key features include: 

1. Seamless Reading: Actuation time is reduced to around 50 ms, making the device significantly more responsive (4 times faster). With quicker dot movement, users can read without any noticeable lag. 

2. Simplicity: Only two components are involved in the movement mechanism, reducing the chances of mechanical failure and lowering production costs. 

Technical Details: 

The core of the device uses Nitinol wire, known for its shape memory property, to control the movement of Braille dots. The wire changes shape when heated, allowing the braille dot to move up and down efficiently. Key innovations include: 

1. Two-State Actuation Mechanism: The Nitinol wire shifts between two states—normal and memorized—through the application of current. It stays in that state due to a bistable compliant mechanism made by 3D printing with PETG material.

2. Heat Transfer Optimization: To achieve the desired speed and energy efficiency, heat transfer calculations were thoroughly analyzed and we found within the safety limits.

The design process involved several iterations, culminating in a compliant mechanism that combines simplicity with high-speed actuation:
State 1: No current; the braille dot remains static.

State 2: With current, the wire contracts and moves the braille dot upward.