Dictionary.net

(Or "refreshable braille display", "refreshabledisplay") An electromechanical device that renders braillewith tiny, independently controlled pins used to represent thestate of dots in braille cells. Each pin, in its "on" state,raises above the top of its hole in the screen; in its "off"state, it drops below the top of its hole. Older systems usedtiny solenoids to control the state of the pins; modernsystems are piezoelectric.Typical dimensions of a braille display are 1 line of 40cells, each cell of two-by-eight dots.