Electroactive polymers for refreshable Braille displays

Abstract

According to the World Health Organization, about 314 million people are visually impaired, with 45 million blind. To benefit from state-of-the-art digital technology and the many emerging computer-controlled devices, these individuals need efficient and inexpensive refreshable full-page Braille displays. This would provide them effective ways to rapidly exchange information (e.g., e-mail and text messaging), as well as providing access to the plethora of information on theWeb and other forms of electronic databases and archives (e.g., educational, employment, and recreational opportunities). The raised dots of Braille code—developed by the 16-year old Louis Braille in 1825—had a dramatic impact on blind people’s ability to read and write. Braille (whose bicentennial birthday is celebrated this year) simplified the 12 raised-dot code of Captain Charles Barbier, who initially created a system to enable Napoleon’s army to communicate silently at night. Braille’s system used only six dots per character, arranged in a rectangular shape along two columns of three each: see Figure 1(a). This modification made the code much easier for fingertips to sense through touch and led to significantly faster reading. A later version uses eight dots with two rows of four dots, increasing the possible combination of signs from 64 to 256: see Figure 1(b). This code represents all printable American Standard Code for Information Interchange (ASCII) characters in a single cell.1 In contrast to the hardcopy form, a refreshable Braille display needs to raise and lower a large array of dense dots, allowing quick tactile perception for rapid reading. Such tactile displays may include single character presentation devices, single line units, and full-page presentation boards filled with characters. (Commercial active Braille devices are limited to single characters and line displays.) Producing a full-page Braille display requires packing many small actuated dots (diameter about 1.65mm) in a small, closely spaced arrangement, raising the Figure 1. The acronym EAP in upper case expressed in the six and eight dot Braille code systems.1