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CONCEPT AND VISUAL STRUCTURE display component, with decimal point.]] A seven segment display, as its name indicates, is composed of seven elements. Individually on or off, they can be combined to produce idealised representations of the Hindu-Arabic Numerals . Each of the numbers 0 , 6 , 7 and 9 may be represented by two or more different glyphs on seven-segment displays. The seven segments are arranged as a s); however, these have mostly been replaced by Dot-matrix displays. Often the seven segments are arranged in an ''oblique'', or '' Italic '', arrangement, which aids readability. The segments of a 7-segment display are referred to by the letters A to G, as follows: AAAAAA F B F B F B GGGGGG E C E C E C DDDDDD DP where the optional DP Decimal Point (an "eighth segment") is used for the display of non-integer numbers. IMPLEMENTATIONS Most separate 7-segment displays use an array of Light-emitting Diode s (LEDs), though other types exist using alternative technologies such as cold Cathode gas discharge, vacuum fluorescent, incandescent filament, Liquid Crystal Display (LCD), etc. For gas price totems and other large signs, electromagnetically flipped light-reflecting segments are still commonly used. An alternative to the 7-segment display in the 1950s through the 1970s was the vacuum tube-like Nixie Tube . Integrated displays also exist, with multiple digits. Some of these integrated displays incorporate their own internal decoder, though most do not – each individual LED is brought out to a connecting pin. digits.]] Seven segment displays can be found in Patent s as early as 1908 (United States patent 974943, for example), but did not achieve widespread use until the advent of LEDs in the 1970s. They are sometimes even used in unsophisticated displays like cardboard "For sale" signs, where the user either applies color to pre-printed segments, or (spray)paints color through a seven-segment digit Template , to compose figures such as product prices or telephone numbers. For many applications, dot-matrix LCDs have largely superseded LED displays, though even in LCDs 7-segment displays are very common. Unlike LEDs, the shapes of elements in an LCD panel are arbitrary since they are formed on the display by a kind of printing process. In contrast, the shapes of LED segments tend to be simple Rectangle s, reflecting the fact that they have to be physically moulded to shape, which makes it difficult to form more complex shapes than the segments of 7-segment displays. However, the high common recognition factor of 7-segment displays, and the comparatively high visual Contrast obtained by such displays relative to dot-matrix digits, makes seven-segment multiple-digit LCD displays very common on basic Calculator s. ALPHABETIC DISPLAY In addition to the ten numerals, seven segment displays can be used to show letters of the Latin , Cyrillic and Greek Alphabet s including Punctuation , 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''. Detailed tables of alternative seven-segment symbols for letters and punctuation are given in the section Character representations, below. The representation of digits and/or letters with seven-segment displays is not standardized by any relevant entity (e.g. and corporate solutions dominate the field of alphabetic seven-segment display, which is usually not considered essential and only used for basic notifications. Using a restricted range of letters that look like (upside-down) digits, seven-segment displays are commonly used by school children to form words and phrases using a technique known as " Calculator Spelling ". CHARACTER REPRESENTATIONS The tables below show alternative seven-segment display patterns for the Arabic numerals, the 26 letters of the English language part of the Latin alphabet, and common related punctuation symbols. See the section Alphabetic display, above, for an overall treatment. Examples SEE ALSO EXTERNAL LINKS |
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