Community hub
0 subscribers8 pages, 0 posts
Recent from talks
All channels
Be the first to start a discussion here.
Be the first to start a discussion here.
Be the first to start a discussion here.
Be the first to start a discussion here.
Contribute something
Welcome to the community hub built to collect knowledge and have discussions related to Nine-segment display.
Nothing was collected or created yet.
Nine-segment display
View on Wikipediafrom Wikipedia
 | This article needs additional citations for verification. (May 2022) |
|
A nine-segment display is a type of display based on nine segments that can be turned on or off according to the graphic pattern to be produced. It is an extension of the more common seven-segment display, having an additional two diagonal or vertical segments (one between the top and the middle, and the other between the bottom and the horizontal segments). It provides an efficient method of displaying alphanumeric characters.
The letters displayed by a nine-segment display are not consistently uppercase or lowercase in shape. A common compromise is to use a lower-case "n" instead of "N". Depending on the design of the display segments, the use of the extra two segments may be avoided whenever possible, as in the Nixxo X-Page "tall" lowercase "r" and "y".
Uses
[edit]
In some Soviet digital calculators of the 1970s, such as the Elektronika 4-71b, 9-segment displays were used to provide basic alphanumerics and avoid confusions with representing numbers in Soviet postcodes.
Digit 3
Different segments for similar glyphs
The extra two bars were slanted forward, allowing for an appropriate-looking И, and to differentiate the numeral 3 from the letter З. The Sharp Compet calculator also uses a 9-segment display, allowing a small range of characters and symbols to be used.
Nine-segment displays are used in many Timex digital watches, and some pagers, such as the Nixxo XPage,[1] the Arch BR502 pager,[2] and the Scope Geo N8T.[3] They are also used in some Epson Stylus printers, and Newport iSeries digital meters.[4] The display used in the iSeries is unique in that it has a vertical extra segment at top, and a fully backwards-leaning slant for the extra segment at bottom. This allows for a somewhat more natural-appearing R and M.
A nine-segment display has been developed for displaying Bengali[5] and Roman numerals.[citation needed]
-
Nine-segment vacuum fluorescent display -
Postal code nine-segment sample on an envelope -
Postcard from Latvia just before its independence
See also
[edit]
References
[edit]- ^ "Primus" (PDF). Primus Ontario English. Archived from the original (PDF) on 2011-07-06. Retrieved 2007-05-12.
- ^ "Br502 Numeric Pager" (PDF). Archived from the original (PDF) on 2007-04-13.
- ^ "GEO N8T" (PDF). Archived from the original (PDF) on 2007-09-29.
- ^ ⁄32 DIN Temperature, Process and Strain PID Controllers (PDF), archived from the original on October 25, 2005
- ^ Miah, Mohammad Badrul Alam; et al. (2015-01-01). "Designing More Effective 9 Segment Display for Bengali and English Digits". Engineering International.
External links
[edit]
Media related to Nine segment displays at Wikimedia Commons
Nine-segment display
View on Grokipediafrom Grokipedia
Overview
Definition and purpose
A nine-segment display is a form of segmented electronic display technology that employs nine individually addressable segments, commonly realized using light-emitting diodes (LEDs), liquid crystals (LCDs), or analogous illumination methods, to generate visual representations of characters through selective activation. This configuration builds upon the foundational seven-segment display by incorporating two supplementary segments—typically positioned as diagonals or internal lines within the figure-eight-like structure—to facilitate more nuanced glyph formation.[5] The primary purpose of the nine-segment display lies in its capacity to render hexadecimal digits (0–9 and A–F) along with rudimentary letters such as A, b, C, d, E, and F, offering enhanced clarity over numeric-only alternatives like the seven-segment design, which struggles with distinguishable letter shapes. By enabling basic alphanumeric output, it supports applications requiring concise symbolic communication, such as status indicators or simple messaging in resource-constrained environments.[5] This technology strikes a balance between operational simplicity and visual readability, allowing for alphanumeric content without the increased complexity, power demands, or cost associated with dot-matrix or comprehensive alphanumeric displays like fourteen- or sixteen-segment variants. Its segments produce stylized yet functional symbols for digits and select letters, prioritizing efficiency in compact interfaces.[5]Basic components
A nine-segment display consists of nine individual segments that form the basic visual elements for rendering alphanumeric characters. These segments are typically arranged in a figure-8-like pattern similar to a seven-segment display, augmented by two additional segments—often diagonal ones positioned in the upper-right and lower-left areas—to enhance the clarity of certain letters and symbols.[6] Common implementations utilize light-emitting diodes (LEDs) as the primary illumination source, with materials such as AlGaInP for red, orange, amber, yellow, or green colors, and InGaN for pure green, blue, or white. Alternatively, liquid crystal displays (LCDs) provide a reflective option, operating without internal illumination for lower power consumption in low-light environments.[7][8] Electrically, these displays support common anode or common cathode configurations, where all segments share a single positive or negative terminal, respectively, to simplify driving circuitry. Forward voltage typically ranges from 1.9V to 3.6V depending on LED color, with a standard forward current of 20mA per segment under DC operation and peak currents up to 100mA for pulsed use.[7][9] Packaging for single-digit modules often features a compact DIP-style enclosure with dimensions around 0.5-inch (12.7mm) character height, though larger variants like 1.5-inch (38mm) exist for visibility. Pin counts range from 10 to 18, including one pin per segment plus one or more commons, with designs supporting multiplexing for multi-digit arrays to reduce pin requirements in larger displays.[7][9]History
Early development
The roots of the nine-segment display lie in early 20th-century segmented technologies for numeric indication. Precursors include bulb-based systems, exemplified by the 1908 patent filed by Frank W. Wood for an illuminated announcement and display signal, which employed light bulbs behind slotted panels to form digit patterns using nine lamp cells per numeral (US Patent 974,943).[10] Seven-segment designs built on these foundations, with practical applications emerging in electromechanical calculators by the 1950s, where mechanical and early electronic indicators used segmented patterns to display digits efficiently. The nine-segment display extended this approach by adding two diagonal segments to enhance character legibility, particularly for alphanumeric rendering. A pivotal advancement occurred in the 1960s and 1970s through solid-state innovations, notably the invention of the first practical visible-spectrum light-emitting diode (LED) in 1962 by Nick Holonyak Jr. at General Electric, which produced red light suitable for compact displays.[11] This technology enabled smaller, more reliable nine-segment arrangements that improved distinction between similar characters like 'b' and 'd' or hexadecimal symbols. Monsanto Company initiated mass production of visible LEDs using gallium arsenide phosphide in 1968, supplying components for early segmented displays and spurring further refinements.[12] The demand for hexadecimal-capable interfaces in the microprocessor era further drove development, as computing and calculator applications required clearer alphanumeric output beyond standard decimal digits. Electronics firms like Monsanto and Texas Instruments adapted general segmented display patents—such as those for LED indicators from the late 1960s—for nine-segment variants, focusing on improved encoding for diverse symbols while maintaining low power and cost efficiency.[13]Commercial adoption
The commercial adoption of nine-segment displays accelerated in the 1970s following advancements in gallium arsenide phosphide (GaAsP) LED technology, which reduced costs and enabled brighter, more efficient alphanumeric displays for consumer electronics. These displays were particularly valued for their ability to render hexadecimal digits and basic letters more clearly than seven-segment alternatives, finding use in early digital calculators and clocks where limited character sets were needed.[14] Notably, in the Soviet Union, nine-segment displays were employed in portable calculators like the Elektronika series (e.g., Elektronika 4-71b) to display numerical results alongside instructional text and limited Cyrillic characters.[15] Key manufacturers including Litronix and National Semiconductor contributed to proliferation by producing modular nine-segment LED components suitable for integration into portable devices. For instance, Litronix supplied displays for handheld calculators in the mid-1970s, while National Semiconductor's NSN500 series offered red nine-segment units with decimal points for numeric and hex applications in clocks and instruments.[16][17] Adoption peaked in the 1980s across calculators, digital watches, and other devices, where nine-segment designs provided a balance of simplicity and versatility for BCD-to-segment decoding standards adapted from seven-segment drivers like the 74LS47. However, by the 1990s, liquid crystal displays (LCDs) overtook them due to superior power efficiency and lower manufacturing costs, particularly in battery-powered consumer tech. Nine-segment LEDs persisted in niche roles, such as specialized hexadecimal indicators and retro-styled devices into the 2000s.[18][19] This era's integration democratized alphanumeric interfaces in everyday gadgets, influencing decoder IC designs and paving the way for more advanced dot-matrix alternatives.[20]Design and variants
Standard segment arrangement
The standard segment arrangement of a nine-segment display extends the traditional seven-segment configuration by incorporating two additional segments to improve alphanumeric rendering. The core seven segments, labeled a through g, form a figure-eight shape: segment a spans the top horizontal, b the upper-right vertical, c the lower-right vertical, d the bottom horizontal, e the lower-left vertical, f the upper-left vertical, and g the middle horizontal. These positions enable the formation of digits 0 through 9 using identical on/off patterns as in seven-segment displays, where the extra segments remain inactive for numeric display. The two supplementary segments, h and i, are typically slanted diagonals positioned across the display's interior—h often as a forward slash from the upper-left to lower-right, and i as a backslash from upper-right to lower-left—to add crossbars for letter formation without disrupting numeric symmetry.[21][22] This geometric layout facilitates clearer representation of letters beyond basic seven-segment limitations; for instance, the letter 'A' is rendered by activating segments a (top), b and f (upper verticals), g (middle), e (lower-left vertical), and h (diagonal crossbar), producing a peaked triangular form with enhanced legibility. Similarly, segments i can support characters like 'S' or 'Z' by providing the necessary slant. The diagonals are angled at approximately 45 degrees relative to the horizontal segments to maintain proportional symmetry and even visual balance across the digit outline.[21] Nine-segment displays with this arrangement are commonly available as LED modules, such as those with a 0.5-inch (12.7 mm) digit height, featuring uniform segment illumination for applications requiring hexadecimal or limited alphanumeric output. Each of the nine segments functions in a binary on/off state, theoretically supporting unique patterns; however, implementations typically restrict to around 16 patterns for hexadecimal characters (0-9, A-F), prioritizing efficiency in encoding and driving. To arrive at , note that each segment has 2 states (on or off), and with 9 independent segments, the total combinations are (9 times), or , computed as via successive doubling: , , up to .[23][21]Alternative configurations
While the standard nine-segment display typically features seven segments augmented by two diagonal elements in the middle for improved alphanumeric rendering, alternative configurations modify this layout to address limitations in character representation or to suit specific applications. One notable variant features a conventional seven-segment display with two additional horizontal segments running through the middle, enabling finer control over the middle bar's illumination. This design improves the depiction of the digit '8'—by allowing the upper and lower halves to be independently lit for a more uniform appearance—and enhances letters such as 'E' and 'H' by supporting partial middle activation without affecting the overall structure. Such configurations are explored in segmented display design discussions for optimizing readability in compact devices.[21] Alternative configurations of the nine-segment display deviate from the baseline geometry to better support certain characters or cultural scripts. A common modification involves vertical center additions, such as two half-height vertical segments in the center (one upper and one lower), which can form a full-height vertical stem when both are activated. This aids in rendering letters like 'b' and 'd' with greater clarity by providing a continuous vertical line from top to bottom, reducing ambiguity in low-resolution displays. This addition maintains the nine-segment count, often with slightly altered positioning of other elements. Custom designs further diversify the layout. For instance, diamond-shaped segments are used in some modules to create a more angular appearance, facilitating sharper edges for numerals and symbols in industrial settings. OPTO PLUS LED's 0.5-inch through-hole (THT) alphanumeric modules employ this diamond configuration for enhanced visual distinction in compact formats.[24] Adaptations for non-Latin scripts represent another category of variation. For Bengali digits, researchers have proposed adjusted diagonal segments to better capture the curved and slanted features of numerals like ১ (one) and ৯ (nine), which differ significantly from Latin counterparts. In a 2015 study published in Engineering International, Miah et al. introduced a 9-segment layout with optimized diagonal orientations and activation patterns, achieving higher display quality than prior 10-segment designs while using fewer segments for both Bengali and English digits.[25] RGB LED versions of these displays have also emerged, allowing color-coded segments for improved visibility or thematic applications, though they require more complex driving circuits. These alternative configurations generally trade off increased wiring complexity and decoding logic for enhanced readability in targeted alphabets or symbols, making them suitable for specialized rather than universal use.[25]Technical operation
Driving circuits
Nine-segment displays are typically driven using electronic circuits that control the illumination of individual LED segments, ensuring efficient power usage and reliable operation. For a single-digit common-cathode nine-segment display, each segment's anode connects to a logic-level output (such as from a microcontroller or decoder) through a current-limiting resistor to prevent overcurrent. A common resistor value is 330 Ω when operating from a 5 V supply, limiting the forward current to approximately 9 mA per segment, assuming a typical LED forward voltage drop of 2 V.[26] This direct-drive approach suits simple applications where GPIO pins from devices like Arduino can directly control the nine segments without additional decoding hardware. Dedicated integrated circuits simplify driving, particularly for multi-digit setups. The MAX6958, for instance, is a 2-wire serial-interfaced driver designed for up to four digits of nine-segment common-cathode LED displays, handling multiplexing internally at a scan rate of 510–1050 Hz to minimize flicker. It sources up to 23 mA per segment at 5 V, with built-in slew-rate limiting to reduce electromagnetic interference, and supports brightness control via pulse-width modulation.[27] While standard BCD-to-segment decoders like the 74HC4511 exist for seven-segment displays, nine-segment variants often require custom logic or no-decode modes in ICs like the MAX6958 for pattern control, as dedicated nine-segment decoders are uncommon. For multi-digit nine-segment displays, time-division multiplexing scans digits sequentially to share segment drive lines, reducing pin count. Transistors such as the 2N2222 NPN are commonly used to switch the common cathodes (or anodes in common-anode configurations), enabling high-current drive from low-power logic signals. The multiplexing refresh rate must exceed 60 Hz—ideally 100 Hz or higher—to prevent visible flicker, achieved by rapidly cycling through digits in software or hardware timers.[28] In common-cathode setups, segment anodes connect across all digits to shared drivers, while digit cathodes connect to transistor collectors; the opposite applies for common-anode.[26] Power considerations focus on maintaining segment currents below 20 mA to ensure LED longevity. The forward current for each segment is calculated as , where is the supply voltage (e.g., 5 V), is the LED forward voltage (typically 2 V for red LEDs), and is the series resistor value. This yields safe currents while accounting for multiplexing duty cycles, which reduce average power per digit (e.g., 25% for four digits). Common-anode and common-cathode configurations differ in polarity but follow the same current principles, with the former sinking current through the common anode.[29] Microcontroller interfaces enhance flexibility for larger arrays. Direct GPIO drive works for single digits using nine pins, but for multi-digit or expanded setups, shift registers like the 74HC595 daisy-chain serial data to parallel outputs for segments and digits, minimizing wiring. For example, one 74HC595 can handle nine segment lines, while additional registers manage digit commons via multiplexing. This serial approach integrates well with Arduino or similar platforms, supporting up to six digits in optimized libraries.[21]Character rendering and encoding
The rendering of characters on a nine-segment display involves selectively activating subsets of the nine segments, labeled a through i, to form recognizable shapes for digits and limited alphanumeric characters. The segments are arranged in a figure-eight-like pattern similar to a seven-segment display, with additional segments h and i typically positioned as diagonals to enhance distinction between similar forms. This configuration allows for binary encoding where each character corresponds to a unique 9-bit pattern indicating which segments are lit (1) or off (0), often implemented via truth tables in driving logic.[3][5] For digits 0 through 9, the patterns closely mirror those of a standard seven-segment display, utilizing segments a through g while leaving h and i off to conserve power and maintain familiarity. For example, the digit 6 is rendered by lighting segments a, c, d, e, f, and g, producing a binary code of 101111100 (assuming segment order a-b-c-d-e-f-g-h-i). Other digits follow suit: 0 lights a-b-c-d-e-f (abcdef: 111111000), 1 lights b-c (bc: 011000000), 8 lights all seven primary segments (abcdefg: 111111100), and so on, as detailed in the activation truth table for English numerals. This encoding ensures compatibility with binary-coded decimal (BCD) inputs, where a 4-bit code selects the appropriate segment pattern via a decoder circuit. Variations in font design may adjust these patterns slightly for better readability, such as extending the tail of 6 to avoid confusion with lowercase b in mixed displays.[3] Support for letters is limited but improved over seven-segment displays through the diagonal segments h and i, enabling clearer representations of hexadecimal characters A through F and select others like L. Uppercase A, for instance, activates segments a, b, c, e, f, h, and i (binary 111011011), forming a peaked top with crossbar g off for distinction from 4. Similarly, B might use a, b, c, d, e, f, g, and i, while lowercase approximations like b rely on vertical segments c, d, e, g, and i. Punctuation such as a hyphen (-) can be shown with just segment g lit (000001000). These patterns allow for basic alphanumeric use in applications like hexadecimal readouts, though full uppercase alphabet coverage is not possible.[5] Encoding schemes typically employ 9-bit binary vectors stored in lookup tables or generated by combinational logic, with each character's truth table defining the segment states. For hexadecimal operation, a 4-bit input extends the BCD decoder to output patterns for A-F, activating the diagonals as needed (e.g., E: a, d, e, f, g, h; binary 100111100). Limitations include inability to render complex letters like J, Q, or S without ambiguity, often resulting in approximations or omissions. In error conditions, all segments may be blanked (000000000) or a subset lit to indicate faults, prioritizing safety in displays. Font variations further optimize clarity, such as distinct curves for 6 versus b by toggling i selectively.[3][5]| Character | Segments Lit | Binary (a-i) |
|---|---|---|
| 6 | a, c, d, e, f, g | 101111100 |
| A | a, b, c, e, f, h, i | 111011011 |
| - | g | 000001000 |