MagnePins: A Modular, Affordable, and DIY Refreshable Braille and Tactile Display

Abstract

Refreshable tactile, braille and shape changing displays have been studied in HCI for many years and have recently become commercially available. These devices offer blind and low vision users the ability to read text directly from a computer application and also the exciting possibility for increased access to dynamic tactile graphics. Commercial devices and research prototypes, however, share similar challenges and tradeoffs including cost, scalability, and miniaturisation. Research prototypes typically have either a low pin count - some only a single cell or line of braille - or a pin pitch and pin dimension far larger than the braille specification. Commercial devices that achieve both high pin count and the 2.5mm pin pitch requirement suffer from high cost, due to the inherent complexity of thousands of individual, precision, electro-mechanical or piezo actuated pins. We present 'MagnePins', an innovative, robust, and open source design that achieves a large pin array (24x89 in our prototype) with braille-compliant pin size and spacing of 2.5mm. It utilises a simple electromagnetic actuation mechanism driven by reliable driver circuitry and can be fabricated economically using cheap mass-produced elements in a well-equipped makerspace. Our tests of the device indicate high accuracy (of up to 99.97%), and in testing with an expert touch reader, it provided high tactile resolution, and easy readability.