Abstract
A new method of Braille display has been proposed for the blind. The device automatically displays 2-dimensional image as a pattern composed of raised dots so as to be recognizable by the tactile sense of a fingertip.
Each raised dot is obtained by elevating a contact pin (0.7mmφ) placed on a tiny bimetal (0.1mm×2mm×15mm) which is heated with a micro-heater. The micro-heater is made of Ni-Cr thin-film (1500Å) which is formed on a glass plate by sputtering. Displacement and time response of the raised dod is estimated on the basis of electrical analogy of thermal circuit and measured by using a solid-state camera. From the estimation and the measured values, it has been found that the relationship between the input voltage V (s) and output displacement X (s) could be presented by the transfer function as
X (s) =α1/s+1/τV (s)
(α=0.125, τ=5sec),
though coefficient a was reduced when a fingertip was placed on a contact pin of the device.
In order to examine the ability and characteristics of tactile pattern recognition by our device, tactile recognition rate of 7 Braille patterns was compared with that of our raised dot patterns corresponding to the Braille ones. Experimental result showed that the tactile recognition by our method had characteristics similar to that of Braille ones.
