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WHAT IS BRAILLE?
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Braille is a tactile writing system used by blind people. It was invented by Louis Braille of France who was blinded in a childhood accident. At the age of 15 he modified a failed military system for reading orders at night without showing any light (night writing), inventing Braille. Braille's system is easier to read compared to night writing and some of its raised-dot competitors in that each symbol fits at once underneath the human fingertip. Braille also gave blind users the ability to write, a great improvement over embossed letter systems.
Braille is also notable for being a binary code that predated the invention of
the computer.
The Braille alphabet
Braille generally consists of cells of 6 raised dots arranged in a grid of two
dots horizontally by three dots vertically. The dots are conventionally numbered
1, 2, 3 from the top of the leftward column and 4, 5, 6 from the top of the
rightward column.
Braille cell The presence or absence of dots gives the coding for
the symbol. Dot height is approximately 0.02 inches (0.5 mm); the horizontal and
vertical spacing between dot centers within a braille cell is approximately 0.1
inches (2.5 mm); the blank space between dots on adjacent cells is approximately
0.15 inches (3.75 mm) horizontally and 0.2 inches (5.0 mm) vertically. A
standard braille page is 11 inches by 11 inches and typically has a maximum of
40 to 42 braille cells per line and 25 lines.
As originally conceived by Louis Braille, a sequence of characters, using the
top 4 dots of the braille cell, represents letters "a" through "j". Dot 3 is
added to each of the "a" through "j" symbols to give letters "k" through "t".
Both of the bottom dots (dots 3 and 6) are added to the symbols for "a" through
"e" to give letters "u", "v", "x", "y", and "z". The letter "w" is an exception
to the pattern because French did not make use of the letter "w" at the time
Louis Braille devised his alphabet, and thus he had no need to encode the letter
"w".
English braille codes the letters and punctuation, and some double letter signs
and word signs directly, but capitalisation and numbers are dealt with by using
a prefix symbol. In practice, Braille produced in the United Kingdom does not
have capital letters.
There are braille codes for representing shorthand (produced on a machine which
embosses a paper tape) and for representing mathematics (Nemeth Braille) and
musical notation (Braille music).
Braille has been extended to an 8 dot code, particularly for use with braille
embossers and refreshable braille displays. In 8 dot braille the additional dots
are added at the bottom of the cell, giving a matrix 4 dots high by 2 dots wide.
The additional dots are given the numbers 7 (for the lower-left dot) and 8 (for
the lower-right dot). 8-dot braille has the advantages that the case of an
individual letter is directly coded in the cell containing the letter and that
all the printable ASCII characters can be represented in a single cell. All 256
possible combinations of 8 dots are encoded by the Unicode standard.
Braille may be produced using a "slate" and a "stylus" in which each dot is
created from the back of the page, writing in mirror image, by hand, or it may
be produced on a braille typewriter or "Perkins Brailler", or produced by a
Braille Embosser attached to a computer. It may also be rendered using a
refreshable Braille display.
The source of this article is
Wikipedia, the free encyclopedia. The text of this
article is licensed under the
GFDL
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