Seven-segment display#Implementations

Seven-segment representation of figures can be found in patents as early as 1903 (in {{US patent|1126641}}), when Carl Kinsley invented a method of telegraphically transmitting letters and numbers and having them printed on tape in a segmented format. In 1908, F. W. Wood invented an 8-segment display, which displayed the number 4 using a diagonal bar ({{US patent|974943}}). In 1910, a seven-segment display illuminated by incandescent bulbs was used on a power-plant boiler room signal panel.{{cite journal |author-first=Warren O. |author-last=Rogers |title=Power Plant Signalling System |journal=Power and the Engineer |volume=32 |number=5 |date=1910-02-01 |pages=204–206 |url=https://books.google.com/books?id=0sIfAQAAMAAJ&pg=PA204 |access-date=6 October 2016 |url-status=live |archive-url=https://web.archive.org/web/20140331102649/http://books.google.com/books?id=0sIfAQAAMAAJ&pg=PA204 |archive-date=31 March 2014}} They were also used to show the dialed telephone number to operators during the transition from manual to automatic telephone dialing.{{cite journal |author-last=Clark |author-first=E. H. |title=Evolution of the Call-Indicator System |journal=Bell Laboratories Record |volume=8 |number=5 |date=December 1929 |pages=171–173 |url=http://www.americanradiohistory.com/Archive-Bell-Laboratories-Record/20s/Bell-Laboratories-Record-1929-12.pdf |access-date=2015-12-19 |url-status=live |archive-url=https://web.archive.org/web/20240413141700/http://www.americanradiohistory.com/Archive-Bell-Laboratories-Record/20s/Bell-Laboratories-Record-1929-12.pdf |archive-date=2024-04-13}} They did not achieve widespread use until the advent of LEDs in the 1970s.

File:Incandescent light seven-segment display prPNr°17.jpg

Some early seven-segment displays used incandescent filaments in an evacuated bulb; they are also known as numitrons.{{cite web |title=IEE Apollo DA-2110 Numitron Tube (DA2110, RCA DR-2110) - Industrial Alchemy |website=industrialalchemy.org |url=https://www.industrialalchemy.org/articleview.php?item=65 |access-date=2020-04-15 |url-status=live |archive-url=https://web.archive.org/web/20200915201814/http://www.industrialalchemy.org/articleview.php?item=65 |archive-date=2020-09-15}} A variation (minitrons) made use of an evacuated potted box. Minitrons are filament segment displays that are housed in DIP (dual in-line package) packages like modern LED segment displays. They may have up to 16 segments.{{cite web |title=Wamco KW-105AL Alphanumeric Minitron Display - Industrial Alchemy |website=industrialalchemy.org |url=https://www.industrialalchemy.org/articleview.php?item=777 |access-date=2020-04-15 |url-status=live |archive-url=https://web.archive.org/web/20200915204740/http://www.industrialalchemy.org/articleview.php?item=777 |archive-date=2020-09-15}}{{cite web |title=Numitron Tube Tutorial |date=21 December 2011 |url=https://hackaday.com/2011/12/21/numitron-tube-tutorial/ |access-date=14 April 2020 |url-status=live |archive-url=https://web.archive.org/web/20180925230213/https://hackaday.com/2011/12/21/numitron-tube-tutorial/ |archive-date=25 September 2018}}{{cite web |title=Incandescent Displays – the Vintage Technology Association |url=http://www.decadecounter.com/vta/tubepage.php?item=10 |access-date=14 April 2020 |url-status=usurped |archive-url=https://web.archive.org/web/20180217005226/http://www.decadecounter.com/vta/tubepage.php?item=10 |archive-date=17 February 2018}} There were also segment displays that used small incandescent light bulbs instead of LEDs or incandescent filaments. These worked similarly to modern LED segment displays.{{cite web |title=Alco MSM-5A Mosaic Indicator Incandescent Display - Industrial Alchemy |website=industrialalchemy.org |url=https://www.industrialalchemy.org/articleview.php?item=845 |access-date=2020-04-15 |url-status=live |archive-url=https://web.archive.org/web/20200915211829/http://www.industrialalchemy.org/articleview.php?item=845 |archive-date=2020-09-15}}

Vacuum fluorescent display versions were also used in the 1970s.{{cite web |title=General Electric Y1938 – the Vintage Technology Association |url=http://www.decadecounter.com/vta/articleview.php?item=94 |access-date=13 November 2020 |url-status=usurped |archive-url=https://web.archive.org/web/20160611100808/http://www.decadecounter.com/vta/articleview.php?item=94 |archive-date=11 June 2016}}

Many early (c. 1970s) LED seven-segment displays had each digit built on a single die. This made the digits very small. Some included magnifying lenses in the design to try to make the digits more legible.{{cite web |title=Litronix Surface Mount Wristwatch LED Display – Industrial Alchemy |url=https://www.industrialalchemy.org/articleview.php?item=3081 |access-date=16 April 2020 |url-status=live |archive-url=https://web.archive.org/web/20180831152511/http://industrialalchemy.org/articleview.php?item=3081 |archive-date=31 August 2018}}{{cite web |title=Litronix DL330 Series LED Displays (Siemens DL340M) - Industrial Alchemy |url=https://www.industrialalchemy.org/articleview.php?item=787 |access-date=16 April 2020 |url-status=live |archive-url=https://web.archive.org/web/20180304050126/https://www.industrialalchemy.org/articleview.php?item=787 |archive-date=4 March 2018}} Other designs used 1 or 2 dies for every segment of the display.{{cite web |title=Soviet AL304V Surface Mount LED - Industrial Alchemy |url=https://www.industrialalchemy.org/articleview.php?item=1167 |access-date=2024-01-21 |url-status=live |archive-url=https://web.archive.org/web/20220928122454/https://www.industrialalchemy.org/articleview.php?item=1167 |archive-date=2022-09-28}}{{cite web |title=Texas Instruments TIA8447 LED Display - Industrial Alchemy |url=https://www.industrialalchemy.org/articleview.php?item=773 |access-date=2024-01-21 |url-status=live |archive-url=https://web.archive.org/web/20220529091352/https://www.industrialalchemy.org/articleview.php?item=773 |archive-date=2022-05-29}}

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.

For many applications, dot-matrix liquid-crystal displays (LCDs) have largely superseded LED displays in general, though even in LCDs, seven-segment displays are common. Unlike LEDs, the shapes of elements in an LCD panel are arbitrary since they are formed on the display by photolithography. 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. 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.

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.

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".

Fuel_prices.jpg|Gas station price display

SHARP ELSIMATE EL-W221.jpg|Calculator that has a tail on the "7" digit

Apollo Guidance Computer-Cité de l'Espace-IMG 1897.jpg|Apollo Guidance Computer control panel reproduction

Marantz CD63SE - fluorescent display in test mode.jpg|Marantax CD63SE CD player with a vacuum fluorescent display in test mode

CD-changer_Marantz_CC-45_01.JPG|Marantz CC-45 CD player display

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 (neon) ([https://www.panaplex.co.uk/ Panaplex]), vacuum fluorescent (VFD), incandescent filaments (Numitron), and others. For gasoline price totems and other large signs, electromechanical seven-segment displays made up of electromagnetically flipped light-reflecting segments are still commonly used. A precursor to the 7-segment display in the 1950s through the 1970s was the cold-cathode, neon-lamp-like nixie tube. Starting in 1970, RCA sold a display device known as the {{Visible anchor|Numitron}} that used incandescent filaments arranged into a seven-segment display.{{cite journal |date=1974-06-07 |title=Advert for RCA NUMITRON Display Devices |journal=Electronic Design |publisher=Hayden |volume=22 |issue=12 |page=163 |url=https://commons.wikimedia.org/wiki/File:RCA_Numitron_display_device_June_1974.jpg |access-date=22 June 2012 |url-status=live |archive-url=https://web.archive.org/web/20140331112707/http://commons.wikimedia.org/wiki/File:RCA_Numitron_display_device_June_1974.jpg |archive-date=31 March 2014}} In USSR, the first electronic calculator "Vega", which was produced from 1964, contains 20 decimal digits with seven-segment electroluminescent display.{{cite web |title=Museum of Soviet Calculators - VEGA |date=29 September 2010 |url=http://www.taswegian.com/MOSCOW/vega.html |url-status=dead |archive-url=https://web.archive.org/web/20100929142141/http://www.taswegian.com/MOSCOW/vega.html |archive-date=29 September 2010}}

In a simple LED package, typically all of the cathodes (negative terminals) or all of the anodes (positive terminals) of the segment LEDs are connected and brought out to a common pin; this is referred to as a "common cathode" or "common anode" device. Hence a 7 segment plus decimal point package will only require nine pins, though commercial products typically contain more pins, and/or spaces where pins would go, in order to match standard IC sockets. Integrated displays also exist, with single or 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 as described.

Multiple-digit LED displays as used in pocket calculators and similar devices used multiplexed displays to reduce the number of I/O pins required to control the display. For example, all the anodes of the A segments of each digit position would be connected together and to a driver circuit pin, while the cathodes of all segments for each digit would be connected. To operate any particular segment of any digit, the controlling integrated circuit would turn on the cathode driver for the selected digit, and the anode drivers for the desired segments; then after a short blanking interval the next digit would be selected and new segments lit, in a sequential fashion. In this manner an eight digit display with seven segments and a decimal point would require only 8 cathode drivers and 8 anode drivers, instead of sixty-four drivers and IC pins.e.g. [http://pdf1.alldatasheet.com/datasheet-pdf/view/170106/VISHAY/TDCR1050M.html DCR 1050m] {{Webarchive|url=https://web.archive.org/web/20140331105445/http://pdf1.alldatasheet.com/datasheet-pdf/view/170106/VISHAY/TDCR1050M.html |date=31 March 2014}} Often in pocket calculators the digit drive lines would be used to scan the keyboard as well, providing further savings; however, pressing multiple keys at once would produce odd results on the multiplexed display.

Although to a naked eye all digits of an LED display appear lit, only one digit is lit at any given time in a multiplexed display. The digit changes at a high enough rate that the human eye cannot see the flashing (on earlier devices it could be visible to peripheral vision).

LED Digital Display.jpg|A multiplexed 4-digit, seven-segment display with only 12 pins

7segment multiplexing.gif|A 4-digit display scanning by columns to make the number 1.234

8-digit-multiplex-7-segment-LED-X-Ray.tif|X-Ray of an 8-digit 7-segment multiplexed LED display from a 1970s calculator

{{Main|Seven-segment display character representations}}

File:7 Segment Display with Labeled Segments.svg File:Slanted7SegmentDisplayWithDot.svg

The seven segments are arranged as a rectangle, with two vertical segments on each side and one horizontal segment each at the top, middle, and bottom. Often the rectangle is oblique (slanted), which may aid readability. In most applications, the segments are of nearly uniform shape and size (usually elongated hexagons, though trapezoids and rectangles can also be used); though in the case of adding machines, the vertical segments are longer and more oddly shaped at the ends, to try to make them more easily readable. The seven elements of the display can be lit in different combinations to represent each of the Arabic numerals.

The individual segments are referred to by the letters "a" to "g", and an optional decimal point (an "eighth segment", referred to as DP) is sometimes used for the display of non-integer numbers.{{cite web |title=Seven Segment Displays |url=http://www.sentex.ca/~mec1995/tutorial/7seg/7seg.html |access-date=2012-11-14 |url-status=dead |archive-url=https://web.archive.org/web/20120105025754/http://www.sentex.ca/~mec1995//tutorial/7seg/7seg.html |archive-date=2012-01-05}}{{cite book |date=1999 |title=Elektrotechnik Tabellen Kommunikationselektronik |edition=3rd |publisher=Westermann Verlag |location=Braunschweig, Germany |isbn=3142250379 |page=110}} A single byte can encode the full state of a seven-segment display, including the decimal point. The most popular bit encodings are gfedcba and abcdefg. In the gfedcba representation, a byte value of 0x06 would turn on segments "c" and "b", which would display a "1".

File:7-segment.svg

The numerical digits 0 to 9 are the most common characters displayed on seven-segment displays. The most common patterns used for each of these are:{{cite book |title=Werkbuch Elektronik |language=de |author-first=Dieter |author-last=Nührmann |publisher=Franzis-Verlag GmbH |publication-place=Munich, Germany |location=Achim, Bremen, Germany |date=1981 |edition=3 |isbn=3-7723-6543-4 |page=695}}

:{{7seg|0|10px|abcdef}} {{7seg|1|10px|bc}} {{7seg|2|10px|abdeg}} {{7seg|3|10px|abcdg}} {{7seg|4|10px|bcfg}} {{7seg|5|10px|acdfg}} {{7seg|6|10px|acdefg}} {{7seg|7|10px|abc}} {{7seg|8|10px|abcdefg}} {{7seg|9|10px|abcdfg}}

Alternative patterns: The numeral 1 may be represented with the left segments, the numerals 6 and 9 may be represented without a "tail", and the numeral 7 represented with a 'tail':For example the fx-50F calculator from Casio and other models from the same manufacturer.

:{{7seg|1*|10px|ef}} {{7seg|6|10px|cdefg}} {{7seg|7|10px|abcf}} {{7seg|9|10px|abcfg}}

In Unicode 13.0, 10 codepoints had been given for segmented digits 0–9 in the Symbols for Legacy Computing block, to replicate early computer fonts that included seven-segment versions of the digits.[https://www.unicode.org/charts/PDF/U1FB00.pdf Official Unicode Consortium code chart] {{Webarchive|url=https://web.archive.org/web/20200605060757/http://www.unicode.org/charts/PDF/U1FB00.pdf |date=2020-06-05}} (PDF) The official reference shows the less-common four-segment "7".

The binary-coded decimal (BCD) 0 to 9 digit values require four binary bits to hold their values. Since four bits (2⁴) can hold 16 values, this means hexadecimal (hex) digits can be represented by four bits too.{{cite web |title=Application Note 3210 – Quick-Start: Driving 7-Segment Displays with the MAX6954 |publisher=Maxim Integrated |orig-year=2004-06-25 |edition=3 |date=March 2008 |type=Application note |url=http://datasheets.maximintegrated.com/en/ds/MAX6955.pdf |access-date=2013-05-06 |url-status=live |archive-url=https://web.archive.org/web/20170320002007/https://datasheets.maximintegrated.com/en/ds/MAX6955.pdf |archive-date=2017-03-20}} Since there are a limited number of segments in seven-segment displays, a couple of the hexadecimal digits are required to be displayed as lowercase letters, otherwise the uppercase letter "B" would be the same as the digit "8", and the uppercase letter "D" would be the same as the digit "0".{{cite web |publisher=Maxim Integrated |title=Driving 7-Segment Displays |date=2004 |url=http://www.maximintegrated.com/app-notes/index.mvp/id/3210 |access-date=2017-03-20 |url-status=live |archive-url=https://web.archive.org/web/20170320000854/https://www.maximintegrated.com/en/app-notes/index.mvp/id/3210 |archive-date=2017-03-20}}{{cite book |title=electronic hexadecimal calculator/converter SR-22 |publisher=Texas Instruments Incorporated |date=1974 |page=7 |edition=Revision A |id=1304-389 Rev A |url=http://www.datamath.net/Manuals/SR-22_US.pdf |access-date=2017-03-20 |url-status=live |archive-url=https://web.archive.org/web/20170320001329/http://www.datamath.net/Manuals/SR-22_US.pdf |archive-date=2017-03-20}}{{cite book |title=electronic calculator – TI programmer |publisher=Texas Instruments Incorporated |date=1977 |page=7 |url=http://www.datamath.net/Manuals/TI-Programmer_US.pdf |access-date=2017-03-28 |url-status=live |archive-url=https://web.archive.org/web/20170328231050/http://www.datamath.net/Manuals/TI-Programmer_US.pdf |archive-date=2017-03-28}}{{cite book |title=electronic calculator – TI LCD programmer |publisher=Texas Instruments Incorporated |date=1981 |page=8 |url=http://www.datamath.net/Manuals/LCD-Programmer_US.pdf |access-date=2017-03-28 |url-status=live |archive-url=https://web.archive.org/web/20170328231558/http://www.datamath.net/Manuals/LCD-Programmer_US.pdf |archive-date=2017-03-28}} The digit "6" must also be displayed with the topmost segment as {{7seg|6|10px}} to avoid ambiguity with the letter "b".

:{{7seg|A|10px}} {{7seg|b|10px}} {{7seg|C|10px}} {{7seg|d|10px}} {{7seg|E|10px}} {{7seg|F|10px}}

Early decoder IC's often produced random patterns or duplicates of digits for 10-15,e.g. the 74LS48 as they were designed to use as few gates as possible and only required to produce 0-9.

Many letters of the Latin alphabet can be reasonably implemented on a seven-segment display. Though not every letter is available, it is possible to create many useful words. By careful choice of words, one can sometimes work around unavailable letters. Uppercase letters "I", "O", "S", "Z" conflict with the common seven-segment representation of digits "1", "0", 5", "2", and the lowercase letter "g" with digit "9". Upper case {{serif|I}} could be put on the left (as lower-case L is shown here) but this is not often done. Lowercase 'b' and 'q' are identical to the alternate numerical digits '6' and '9'.

:

class="wikitable" style="text-align:center;background:#FFF" |+ Latin alphabet ! !! A !! B !! C !! D !! E !! F !! G !! H !! I !! J !! K !! L !! M !! N !! O !! P !! Q !! R !! S !! T !! U !! V !! W !! X !! Y !! Z
Upper | {{7seg|А|10px}} || || {{7seg|C|10px}} || || {{7seg|E|10px}} || {{7seg|F|10px}} || {{7seg|G|10px}} || {{7seg|H|10px}} || style="background: #FEE|{{7seg|I*|10px}} || {{7seg|J*|10px}} || || {{7seg|L|10px}} || {{nowrap|{{7seg|M|10px|abef}}{{7seg|M|10px|abcf}}}} || || style="background: #FEE|{{7seg|O|10px}} || {{7seg|P|10px}} || || || style="background: #FEE|{{7seg|S|10px}} || || {{7seg|U|10px}} || || {{nowrap|{{7seg|W|10px|cdef}}{{7seg|W|10px|bcde}}}} || || || style="background: #FEE|{{7seg|Z|10px}}
Lower | {{7seg|a*|10px}} || {{7seg|b|10px}} || {{7seg|c|10px}} || {{7seg|d|10px}} || {{7seg|e|10px|abdefg}} || || style="background: #FEE|{{7seg|g*|10px}} || {{7seg|h|10px}} || {{7seg|i#|10px}} || {{7seg|j|10px|bcd}} || || {{7seg|l|10px}} || || {{7seg|n|10px}} || {{7seg|o|10px}} || || {{7seg|q|10px}} || {{7seg|r|10px}} || || {{7seg|t|10px}} || {{7seg|u|10px}} || || || || {{7seg|y|10px}} ||

The following are some real world English word examples seen on actual electronic equipment (first line appeared on some CD players):

:{{7seg|O|10px}}{{7seg|P|10px}}{{7seg|E|10px}}{{7seg|N|10px}}, {{7seg|C|10px}}{{7seg|L|10px}}{{7seg|O|10px}}{{7seg|S|10px}}{{7seg|E|10px}}, {{7seg|P|10px}}{{7seg|L|10px}}{{7seg|A|10px}}{{7seg|Y|10px|bcdfg}}, {{7seg|P|10px}}{{7seg|A|10px}}{{7seg|U|10px}}{{7seg|S|10px}}{{7seg|E|10px}}, {{7seg|S|10px}}{{7seg|H|10px}}{{7seg|U|10px}}{{7seg|F|10px}}{{7seg|F|10px}}{{7seg|L|10px}}{{7seg|E|10px}}, {{7seg|n|10px}}{{7seg|o|10px}} {{7seg|d|10px}}{{7seg|I|10px|bc}}{{7seg|S|10px}}{{7seg|C|10px}}

:{{7seg|S|10px}}{{7seg|t|10px}}{{7seg|A|10px}}{{7seg|r|10px}}{{7seg|t|10px}}, {{7seg|S|10px}}{{7seg|t|10px}}{{7seg|o|10px}}{{7seg|P|10px}}, {{7seg|r|10px}}{{7seg|u|10px}}{{7seg|n|10px}}, {{7seg|F|10px}}{{7seg|A|10px}}{{7seg|I|10px|bc}}{{7seg|L|10px}}, {{7seg|E|10px}}{{7seg|r|10px}}{{7seg|r|10px}}{{7seg|o|10px}}{{7seg|r|10px}}, {{7seg|S|10px}}{{7seg|E|10px}}{{7seg|t|10px}}{{7seg|U|10px}}{{7seg|P|10px}}, {{7seg|H|10px}}{{7seg|E|10px}}{{7seg|L|10px}}{{7seg|P|10px}}

:{{7seg|M|10px|abef}}{{7seg|M|10px|abcf}}{{7seg|o|10px}}{{7seg|d|10px}}{{7seg|E|10px}}, {{7seg|o|10px}}{{7seg|n|10px}}, {{7seg|O|10px}}{{7seg|F|10px}}{{7seg|F|10px}}, {{7seg|y|10px}}{{7seg|E|10px}}{{7seg|S|10px}}, {{7seg|n|10px}}{{7seg|o|10px}}, {{7seg|H|10px}}{{7seg|o|10px}}{{7seg|t|10px}}, {{7seg|C|10px}}{{7seg|o|10px}}{{7seg|L|10px}}{{7seg|d|10px}}

File:Common segment displays.svg-, 14-, and 16-segment displays shown side by side]]

There are also fourteen- and sixteen-segment displays (for full alphanumerics); however, these have mostly been replaced by dot matrix displays. 22-segment displays capable of displaying the full ASCII character set{{cite web |title=DL-3422 4-digit 22-segment alphanumeric Intelligent Display preliminary data sheet |website=Internet Archive |publisher=Litronix 1982 Optoelectronics Catalog |page=82 |url=https://archive.org/stream/bitsavers_litronixdaOptoelectronicsCatalog_31011858/1982_Litronix_Optoelectronics_Catalog#page/n81/mode/2up |access-date=2016-09-03}} were briefly available in the early 1980s but did not prove popular.

• Eight-segment display
• Nine-segment display
• Fourteen-segment display
• Sixteen-segment display
• Dot matrix display
• Nixie tube display
• Vacuum fluorescent display

{{Reflist|refs=

{{cite magazine |title=junior cookbook: a few healthy recipes to keep your computer in shape |author-first1=H. P. |author-last1=Diehl |author-first2=H. D. |author-last2=De Mulder |date=April 1981 |volume=1981 |issue=72 |magazine=elektor (UK) – up-to-date electronics for lab and leisure |language=en |pages=4-28 – 4-31 [4-30 Figure 4] |url=https://worldradiohistory.com/UK/Elektor/80s/Elektor-1981-04.pdf |access-date=2020-07-03 |url-status=live |archive-url=https://web.archive.org/web/20200703164044/https://worldradiohistory.com/UK/Elektor/80s/Elektor-1981-04.pdf |archive-date=2020-07-03}}

}}

{{Commons|Seven segment display}}

• [http://www.uize.com/examples/seven-segment-display.html Interactive Demonstration of a Seven Segment Display]
• [https://www.dnatechindia.com/Tutorial/8051-Tutorial/Interfacing-7-Seg-Display-to-Microcontroller.html Interfacing Seven Segment Display to 8051 Microcontroller]
• [https://circuitdigest.com/microcontroller-projects/0-99-counter-using-avr-atmega32 Interfacing 7-Segment Display with AVR Microcontroller]

{{Display technology}}

Category:Display technology