In USSR, the first electronic calculator "Vega", which was produced from 1964, contains 20 decimal digits with seven-segment electroluminescent display. Starting in 1970, RCA sold a display device known as the Numitron that used incandescent filaments arranged into a seven-segment display. A precursor to the 7-segment display in the 1950s through the 1970s was the cold-cathode, neon-lamp-like nixie tube. For gasoline price totems and other large signs, vane displays made up of electromagnetically flipped light-reflecting segments (or "vanes") are still commonly used. Seven-segment displays may use a liquid crystal display (LCD), a light-emitting diode (LED) for each segment, an electrochromic display, or other light-generating or controlling techniques such as cold cathode gas discharge (Panaplex), vacuum fluorescent (VFD), incandescent filaments (Numitron), and others. Implementations A vane display at a gas station A multiplexed 4-digit, seven-segment display with only 12 pins A 4-digit display scanning by columns to make the number 1.234 X-Ray of an 8-digit 7-segment multiplexed LED display from a 1970s calculator 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". The seven-segment display has inspired type designers to produce typefaces reminiscent of that display (but more legible), such as New Alphabet, "DB LCD Temp", "ION B", etc. However, the easy recognition of seven-segment displays, and the comparatively high visual contrast obtained by such displays relative to dot-matrix digits, makes seven-segment multiple-digit LCD screens very common on basic calculators. In contrast, the shapes of LED segments tend to be simple rectangles, because they have to be physically moulded to shape, which makes it difficult to form more complex shapes than the segments of seven-segment displays. Unlike LEDs, the shapes of elements in an LCD panel are arbitrary since they are formed on the display by photolithography. The seven-segment pattern is sometimes used in posters or tags, where the user either applies color to pre-printed segments, or applies color through a seven-segment digit template, to compose figures such as product prices or telephone numbers.įor many applications, dot-matrix liquid-crystal displays (LCDs) have largely superseded LED displays in general, though even in LCDs, seven-segment displays are common. Other designs used 1 or 2 dies for every segment of the display. Some included magnifying lenses in the design to try to make the digits more legible. 1970s) LED seven-segment displays had each digit built on a single die. Vacuum fluorescent display versions were also used in the 1970s. These worked similarly to modern LED segment displays. There were also segment displays that used small incandescent light bulbs instead of LEDs or incandescent filaments. Minitrons are filament segment displays that are housed in DIP ( dual in-line package) packages like modern LED segment displays. A variation (minitrons) made use of an evacuated potted box. Some early seven-segment displays used incandescent filaments in an evacuated bulb they are also known as numitrons. They did not achieve widespread use until the advent of LEDs in the 1970s. They were also used to show the dialed telephone number to operators during the transition from manual to automatic telephone dialing. In 1910, a seven-segment display illuminated by incandescent bulbs was used on a power-plant boiler room signal panel. Wood invented an 8-segment display, which displayed the number 4 using a diagonal bar ( U.S. patent 1,126,641), when Carl Kinsley invented a method of telegraphically transmitting letters and numbers and having them printed on tape in a segmented format. Seven-segment representation of figures can be found in patents as early as 1903 (in U.S. Seven-segment displays are widely used in digital clocks, electronic meters, basic calculators, and other electronic devices that display numerical information. Form of electronic display device for displaying decimal numeralsĪ typical 7-segment LED display component, with decimal point in a wide DIP-10 packageĪ seven-segment display is a form of electronic display device for displaying decimal numerals that is an alternative to the more complex dot matrix displays.
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