- Seven-segment display character representations
The topic of seven-segment display character representations revolves around the various shapes of
numerical digit s, letters, andpunctuation devisable onseven-segment display s. Such representation of characters is not standardized by any relevant entity (e.g. ISO,IEEE orIEC ).Digit conventions
Two basic conventions can be seen for
Arabic numerals : one lights the additional segment in 6 (segment A), 7 (F) and 9 (D); the other, moreanglophone one does not. Military, mission critical, and safety-of-life applications prefer the latter. The idea is to use a display font where a single burned out or missing segment in a digit will not display as a different valid digit.Alphabetic letters
In addition to the ten digits, seven-segment displays can be used to show letters of the latin, cyrillic and
greek alphabet s includingpunctuation , but only few representations are unambiguous and intuitive at the same time: uppercase "A", "B", "C", "E", "F", "G", "H", "I", "J", "L", "N", "O", "P", "S", "U", "Y", "Z", and lowercase "a", "b", "c", "d", "e", "g", "h", "i", "n", "ñ", "o", "q", "r", "t", "u".Also, alphabetic letters, and many other characters, are much clearer, and unambiguously shown on the currently ubiquitous and low-priceddot matrix display s, as well as on fourteen-segment andsixteen-segment display s. All this obviates the need for seven-segment displays to show letters in all but the most special cases.One such special case is the display of the letters A–F when denoting the
hexadecimal values (digits) 10–15. These are needed on some scientific calculators, and are used with some test displays on electronic equipment. Although there is no official standard, most devices displaying hex digits use the unique forms shown in the leftmost column of the Latin alphabet section below — uppercase A, C, E, and F, and lowercase b and d.All in all,
ad hoc and corporate solutions dominate the field of using seven-segment displays to show general words and phrases. Such applications of seven-segment displays are usually not considered essential and are only used for basic notifications on consumer electronics appliances (as is the case of this article's Example phrases), and as internal test messages on equipment under development.Display pattern tables
The tables below show alternative seven-segment display patterns for the
Arabic numerals , the 26 letters of the English language part of theLatin alphabet , and theGreek alphabet . Finally, some examples of words spelled using the patterns are shown.Arabic numerals
Examples
The following phrases come from a
portable media player 's seven-segment display. They give a good illustration of an application where a 7-segment display may be sufficient for displaying letters, since the relevant messages are neither life/mission critical, nor in any significant risk of being misunderstood, much due to the limited number and rigid domain specificity of the messages. As such, there is no direct need for a more expressive display in this case, although even a slightly wider repertoire of messages would require at least a 14- or 16-segment display, if not a dot matrix one.
External links
* [http://www.twyman.org.uk/Fonts/ Harvey Twyman's seven-segment TrueType fonts]
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