Refreshable braille display

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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 computer monitor can use it to read text output. 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. Deafblind computer users may also use refreshable braille displays.

Mechanical details[edit]

A Baum David System 90 special-purpose computer for the blind, with a braille "screen" and special keyboard

The base of a refreshable braille display often integrates a pure braille keyboard. Similar to the Perkins Brailler, the input is performed by two sets of four keys on each side, while output is via a refreshable braille display consisting of a row of electro-mechanical character cells, each of which can raise or lower a combination of eight round-tipped pins. Other variants exist that use a conventional QWERTY keyboard for input and braille pins for output, as well as input-only and output-only 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.

The mechanism which raises the dots uses the piezo effect of some crystals, whereby they 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 a crystal for each dot of the display, i.e. eight per character.

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 between 18 and 40 cells exist in some notetaker devices.


The software that controls the display is called a screen reader. It 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 Application Programming Interface 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.

Future designs[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] Both wheels are still in the process of commercialization.[clarification needed] 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.
  • Designs for a full braille computer monitor have been patented but not yet produced.[2]
  • A full-page braille display with 1,000 cells (25 lines of 40 cells) was developed in 2015 by the Tactisplay Corp.[3] With total 12,000 pixels configured in 120*100, it can show any BANA compatible braille graphic page in 8 seconds. This video shows operation of the device. Unfortunately, the device is in the process of commercialization.
Braille Tablet Computer developed by Metec.
  • A group of researchers from the University of Michigan is developing a refreshable braille tablet, similar to a Kindle, as seen in this video. The tablet itself features fully refreshable pages containing raised bumps, a marked improvement from current devices that can only display one line of Braille text at a time.
  • The 4Blind company based in Canada in 2019 presented a prototype of a device operating without piezo effect of some crystals. The video was presented on the official website. The upcoming version 6.4: dimensions 50 by 28 pins, planned readiness is September 2019.[5]
  • In 2018, the German production concern Metec presented a device in the form of a braille tablet which, unlike its predecessors, has a field size of 120 x 97 mm in which 8 lines of 16 characters each are placed. The device allows blind users to study in a tactile way graphics, maps. The cost of the device (as of 2019) is 13,800 euros.[6]
  • A device made in the form of a glove, Braille glove, declared as a technological solution replacing the Braille display is also known. It used for communication of deafblind people.[7]

Braille e-book[edit]

See also[edit]


  1. ^ "Flemish researcher (Tiene Nobels) develops braille computer mouse / Vlaamse onderzoekster (Tiene Nobels) ontwikkelt braillecomputermuis". ZDNet.
  2. ^ Braille computer monitor - Patent 6700553
  3. ^ "Full Page Braille Display being Launched by Tactisplay Corp". Tactisplay Corp.
  4. ^ Thorpe, Devin (20 December 2016). "These 6 Women Undergrads At MIT Invented A Game Changer For The Blind". Forbes.
  5. ^ "Braille Pad — Our solutions — About — 4BLIND". Retrieved 2019-08-01.
  6. ^ "Two-dimensional, touch-sensitive graphic displays - metec AG". Retrieved 2019-08-01.
  7. ^ City, MATCHUP+ Fukuoka. "4Blind". MATCHUP+ Fukuoka City. Retrieved 2019-08-02.

External links[edit]