Refreshable braille display
A refreshable braille display or braille terminal is an electro-mechanical device for displaying braille characters, usually by means of round-tipped pins raised through holes in a flat surface. Visually impaired computer users who cannot use a standard computer monitor can use it to read text output. Deafblind computer users may also use refreshable braille displays.
Speech synthesizers are also commonly used for the same task, and a blind user may switch between the two systems or use both at the same time depending on circumstances.
Software[edit]
The software gathers the content of the screen from the operating system, converts it into braille characters and sends it to the display.
Screen readers for graphical operating systems are especially complex, because graphical elements like windows or slidebars have to be interpreted and described in text form. Modern operating systems usually have an API to help screen readers obtain this information, such as UI Automation (UIA) for Microsoft Windows, VoiceOver for macOS and iOS, and AT-SPI for GNOME.
Rotation-wheel Braille display[edit]
A rotating-wheel Braille display was developed in 2000 by the National Institute of Standards and Technology (NIST) and another at the Leuven University in Belgium.[1] In these units, braille dots are put on the edge of a spinning wheel, which allows the user to read continuously with a stationary finger while the wheel spins at a selected speed. The braille dots are set in a simple scanning-style fashion as the dots on the wheel spin past a stationary actuator that sets the braille characters. As a result, manufacturing complexity is greatly reduced and rotating-wheel braille displays, when in actual production, should be less expensive than traditional braille displays.