Dot shape and legibility analysis of multilayer UV ink-jet printed Braille text

Multilayer UV ink-jet is recognized as alternative printing technology to traditional embossing, thermo-forming, screen-printing and other Braille printing techniques. Advantages of multilayer printing are extensive possibilities of dot shape and dot height modulation according to the requirements of blind and visually impaired people associations and legislation. Braille used for the pharmaceutical packaging is prescribed according to EU Directive 2004/27/EC, cell and dot dimensions are specified in the Standard EN 15823, in other fields there are only recommendations and specifications in force. Braille is usually adapted to different users, languages, scope, media, and printing processes. A set of samples with different Braille text sizes using conventional rounded dot shape and alternative dot shapes with additional small raised dot over basic dot, dots with incision and other dot shapes were prepared using multilayer UV ink-jet printing technique. Cell and dot dimensions and shape profile were obtained using different profile-meters and image analysis techniques. Legibility test has been carried out at the „Zavod za slepo in slabovidno mladino Ljubljana“ (Centre to help blind and partially sighted persons) and with the help of other blind people of all ages and Braille skills. It is evident from the results that the successful reading of the blind is greatly dependent on the shape and height of the dots of Braille. A survey on their answers and their comments gave us important information and directions for further research