A refreshable Braille display is an electro-mechanical device for displaying Braille characters, usually by means of raising dots through holes in a flat surface. The display sits under the computer keyboard. It is used to present text to computer users who are blind and cannot use a normal computer monitor. Speech synthesizers are also commonly used for the same task, and a blind user may switch between the two systems depending on circumstances. A Czech braille calendar There is also an asteroid 9969 Braille Braille is a tactile writing system used by blind people. ... QWERTY computer keyboard A computer keyboard is a peripheral modelled after the typewriter keyboard. ... The tower of a personal computer (specifically a Power Mac G5). ... Blindness can be defined physiologically as the condition of lacking sight. ... Nineteen inch (48 cm) CRT computer monitor A computer display, monitor or screen is a computer peripheral device capable of showing still or moving images generated by a computer and processed by a graphics card. ... Speech synthesis is the artificial production of human speech. ...

Because of the complexity of producing a reliable display that will cope with daily wear and tear, these displays are expensive. Usually, only 40 or 80 Braille cells are displayed. Models with 18-40 cells exist in some notetaker devices.

On some models the position of the cursor is represented by vibrating the dots, and some models have a switch associated with each cell to move the cursor to that cell directly. Cursor is a term that frequently refers to a feature of a computer user interfaces. ...

The mechanism which raises the dots uses the piezo effect: Some crystals expand, when a voltage is applied to them. Such a crystal is connected to a lever, which in turn raises the dot. There has to be such a crystal for each dot of the display, i.e eight per character. Piezoelectricity is the ability of certain crystals to produce a voltage when subjected to mechanical stress. ...

The software, that controls the display is called a screen reader. It gathes the content of the screen from the operating system, converts it into braille characters and sends it to the display. Screen readers for graphical operation systems are especially complex, because graphical elements like windows or slidebars have to be interpreted and described in text form. A screen reader is a software application that attempts to identify and interpret what is being displayed on the screen. ... In computing, an operating system (OS) is the system software responsible for the direct control and management of hardware and basic system operations. ...

A new development, called the rotating-wheel Braille display, was developed in 2000 by the National Institute of Standards and Technology (NIST) and is still in the process of commercialization. Braille dots are put on the edge of a spinning wheel, and allows the blind 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 spins past a stationary actuator that sets the Braille characters. As a result, manufacturing complexity is greatly reduced and rotating-wheel Braille displays will be much more inexpensive than traditional Braille displays. 2000 is a leap year starting on Saturday of the Gregorian calendar. ... As a non-regulatory agency of the United States Department of Commerce’s Technology Administration, the National Institute of Standards (NIST) develops and promotes measurement, standards, and technology to enhance productivity, facilitate trade, and improve the quality of life. ... A wheel is a circular object that together with an axle allows low friction motion, e. ... An actuator is the mechanism by which an agent acts upon an environment. ...

External link

• NIST Braille Display Project