Use and function of a Braille display:

 

A refreshable electronic Braille display is a tactile device that enables the user to read the contents of the computer screen by touch in Braille. Thus blind persons can work with a PC without help.

Each single dot of a Braille character is set or pulled down by electronically driving a piezo-actuator. Modern Braille displays have 8-dot characters with which 256 signs (ASCII or UNI-code) can be shown. Braille displays are nowadays mainly connected to the computer via USB, Bluetooth or WLAN. They are controlled with a "Screen-reader" software, which translates the contents of the screen to the Braille line and has a speech output.

The Braille displays vary in size from 12 to 80 cells showing only a small part of the screen – max. 80 signs of a screen line. To solve this problem, the Braille displays have navigation keys with which the part of the screen, which is shown on the display, can be moved to the top, to the bottom, to the right and to the left. The less cells a display has the more moves the user has to make. However, most Braille displays are programmed in such way that certain states can be reached automatically.

State of the art Braille displays have the so-called cursor-routing. Each Braille cell has a small button above or below the dots. When putting this button the cursor will be sent to the corresponding position on the screen. This is mainly used when a text shall be corrected while reading it.

Since Braille displays have a very high technical standard and are produced in small quantities the production costs are rather high. Nevertheless, the long lifetime and the high benefit justify the buy.

 

 

 

 

Dots of a Braille line:

Here you see dots which form Braille characters

 

 

 

Example of a Braille display:

A standard keyboard is placed on the housing of a Braille display

 

 

 

 

History of Braille

From Wikipedia, the free encyclopedia

 

The Braille system is a method that is widely used by blind people to read and write. Braille was devised in 1821 by Louis Braille, a blind Frenchman. Each Braille character or cell is made up of six dot positions, arranged in a rectangle containing two columns of three dots each. A dot may be raised at any of the six positions to form sixty-four possible subsets, including the arrangement in which no dots are raised. For reference purposes, a particular permutation may be described by naming the positions where dots are raised, the positions being universally numbered 1 to 3, from top to bottom, on the left, and 4 to 6, from top to bottom, on the right. For example, dots 1-3-4 would describe a cell with three dots raised, at the top and bottom in the left column and on top of the right column, i.e., the letter m. The lines of horizontal Braille text are separated by a space, much like visible printed text, so that the dots of one line can be differentiated from the Braille text above and below. Punctuation is represented by its own unique set of characters.

The Braille system was based on a method of communication originally developed by Charles Barbier in response to Napoleon's demand for a code that soldiers could use to communicate silently and without light at night called night writing. Barbier's system was too complex for soldiers to learn, and was rejected by the military. In 1821 he visited the National Institute for the Blind in Paris, France, where he met Louis Braille. Braille identified the major failing of the code, which was that the human finger could not encompass the whole symbol without moving, and so could not move rapidly from one symbol to another. His modification was to use a 6 dot cell — the Braille system — which revolutionized written communication for the blind.

 

Useful links

 

http://en.wikipedia.org/wiki/Braille#The_Braille_alphabet

 

National Federation of the Blind / english
http://www.nfb.org/·

 

The Story of Louis Braille / englisch
http://www.his.com/~pshapiro/braille.html

·