1936 neon marquee sign for a theater in Auburn, California, as rebuilt in 2006. The large letters on the tower are illuminated in a timed sequence that repeats, "S", "ST", "STA", "STAT", "STATE", off.
In the signage industry, neon signs are electric signs lighted by long luminous gas-discharge tubes that contain rarefied neon or other gases. They are the most common use for neon lighting,[1] which was first demonstrated in a modern form in December 1910 by Georges Claude at the Paris Motor Show.[2] While they are used worldwide, neon signs were popular in the United States from about the 1920s to 1950s.[3] The installations in Times Square, many originally designed by Douglas Leigh, were famed, and there were nearly 2,000 small shops producing neon signs by 1940.[4][5] In addition to signage, neon lighting is used frequently by artists and architects,[4][6][7] and (in a modified form) in plasma display panels and televisions.[8][9] The signage industry has declined in the past several decades, and cities are now concerned with preserving and restoring their antique neon signs.
Light emitting diode arrays can be formed and covered with a light diffuser to simulate the appearance of neon lamps.[10]
History
Neon sign
The neon sign is an evolution of the earlier Geissler tube,[11] which is a sealed glass tube containing a "rarefied" gas (the gas pressure in the tube is well below atmospheric pressure). When a voltage is applied to electrodes inserted through the glass, an electrical glow discharge results. Geissler tubes were popular in the late 19th century,[12] and the different colors they emitted were characteristics of the gases within. They were unsuitable for general lighting, as the pressure of the gas inside typically declined with use. The direct predecessor of neon tube lighting was the Moore tube, which used nitrogen or carbon dioxide as the luminous gas and a patented mechanism for maintaining pressure. Moore tubes were sold for commercial lighting for a number of years in the early 1900s.[13][14]
The discovery of neon in 1898 by British scientists William Ramsay and Morris W. Travers included the observation of a brilliant red glow in Geissler tubes.[15] Travers wrote, "the blaze of crimson light from the tube told its own story and was a sight to dwell upon and never forget."[15] Following neon's discovery, neon tubes were used as scientific instruments and novelties.[16] A sign created by Perley G. Nutting and displaying the word "neon" may have been shown at the Louisiana Purchase Exposition of 1904, although this claim has been disputed;[17] in any event, the scarcity of neon would have precluded the development of a lighting product. After 1902, Georges Claude's company in France, Air Liquide, began producing industrial quantities of neon, essentially as a byproduct of their air liquefaction business.[14] From December 3–18, 1910, Claude demonstrated two 12-metre (39ft) long bright red neon tubes at the Paris Motor Show.[2][18] This demonstration lit a peristyle of the Grand Palais (a large exhibition hall).[19] Claude's associate, Jacques Fonsèque, realized the possibilities for a business based on signage and advertising. By 1913 a large sign for the vermouth Cinzano illuminated the night sky in Paris, and by 1919 the entrance to the Paris Opera was adorned with neon tube lighting.[4] Over the next several years, patents were granted to Claude for two innovations still used today: a "bombardment" technique to remove impurities from the working gas of a sealed sign, and a design for the internal electrodes of the sign that prevented their degradation by sputtering.[14]
In 1923, Georges Claude and his French company Claude Neon introduced neon gas signs to the United States[20] by selling two to a Packard car dealership in Los Angeles. Earle C. Anthony purchased the two signs reading "Packard" for $1,250 apiece.[2] Neon lighting quickly became a popular fixture in outdoor advertising. The signs–dubbed "liquid fire"–were visible in daylight; people would stop and stare.[21] What may be the oldest surviving neon sign in the United States, still in use for its original purpose, is the sign "Theatre" (1929) at the Lake Worth Playhouse in Lake Worth Beach, Florida.
The next major technological innovation in neon lighting and signs was the development of fluorescent tube coatings.[22] Jacques Risler received a French patent in 1926 for these.[5] Neon signs that use an argon/mercury gas mixture emit a good deal of ultraviolet light. When this light is absorbed by a fluorescent coating, preferably inside the tube, the coating (called a "phosphor") glows with its own color. While only a few colors were initially available to sign designers, after the Second World War, phosphor materials were researched intensively for use in color televisions. About two dozen colors were available to neon sign designers by the 1960s, and today there are nearly 100 available colors.[7]
Suddenly we were in down-town Seattle and lights were exploding around me like skyrockets on the Fourth of July. Red lights, blue lights, yellow lights, green, purple, white, orange, punctured the night in a million places and tore the black satin pavement to shreds. I hadn’t seen neon lights before. They had been invented, or at least put in common use, while I was up in the mountains and in that short time the whole aspect of the world had changed. In place of dumpy little bulbs sputteringly spelling out Café or Theatre, there were long swooping spirals of pure brilliant colour. A waiter outlined in bright red with a blazing white napkin over his arm flashed on and off over a large Café. Puget Sound Power and Light Company cut through the rain and darkness, bright blue and cheery. Cafês, theatres, cigar stores, stationery stores, real estate offices with their names spelled out in molten colour, welcomed me to the city.
An enormous number of colors can be created by combinations of different gases and fluorescent coatings in the tube.A neon sample display case in a glass studio
Neon tube signs[23][24][25][26] are produced by the craft of bending glass tubing into shapes. A worker skilled in this craft is known as a glass bender, neon bender or tube bender. The neon tube is made out of 4 or 5-foot long straight sticks of hollow glass sold by sign suppliers to neon shops worldwide, where they are manually assembled into individual custom designed and fabricated lamps.
Blue neon sign in a pastry shop
Tubing in external diameters ranging from about 8–15mm with a 1mm wall thickness is most commonly used, although 6mm tubing is now commercially available in colored glass tubes. The tube is heated in sections using several types of burners that are selected according to the amount of glass to be heated for each bend. These burners include ribbon, cannon, or crossfires, as well as a variety of gas torches. Ribbon burners are strips of fire that make the gradual bends, while crossfires are used to make sharp bends.
The interior of the tubes may be coated with a thin phosphorescent powder coating, affixed to the interior wall of the tube by a binding material. The tube is filled with a purified gas mixture, and the gas ionized by a high voltage applied between the ends of the sealed tube through cold cathodes welded onto the ends. The color of the light emitted by the tube may be just that coming from the gas, or the light from the phosphor layer. Different phosphor-coated tubing sections may be butt welded together using glass working torches to form a single tube of varying colors, for effects such as a sign where each letter displays a different color letter within a single word.
"Neon" is used to denote the general type of lamp, but neon gas is only one of the types of tube gases principally used in commercial application. Pure neon gas is used to produce only about one-third of the colors (mostly shades of red and orange, and some warmer or more intense shades of pink). The greatest number of colors (including all shades of blue, yellow, green, violet, and white, as well as some cooler or softer shades of pink) produced by filling with another inert gas, argon, and a drop of mercury (Hg) which is added to the tube immediately after purification. When the tube is ionized by electrification, the mercury evaporates into mercury vapor, which fills the tube and produces strong ultraviolet light. The ultraviolet light thus produced excites the various phosphor coatings designed to produce different colors. Even though this class of neon tubes use no neon at all, they are still denoted as "neon." Mercury-bearing lamps are a type of cold-cathode fluorescent lamps.
Each type of neon tubing produces two different possible colors, one with neon gas and the other with argon/mercury. Some "neon" tubes are made without phosphor coatings for some of the colors. Clear tubing filled with neon gas produces the ubiquitous yellowish orange color with the interior plasma column clearly visible, and is the cheapest and simplest tube to make. Traditional neon glasses in America over 20 years old are lead glass that are easy to soften in gas fires, but recent environmental and health concerns of the workers has prompted manufacturers to seek more environmentally safe special soft glass formulas. One of the vexing problems avoided this way is lead glass' tendency to burn into a black spot emitting lead fumes in a bending flame too rich in the fuel/oxygen mixture. Another traditional line of glasses was colored soda lime glasses coming in a myriad of glass color choices, which produce the highest quality, most hypnotically vibrant and saturated hues. Still more color choices are afforded in either coating, or not coating, these colored glasses with the various available exotic phosphors.
Neon lights are exceptionally long-lasting due to their vibrant colors and the ability to craft tubes that function for decades. This longevity is crucial to their economic viability, given the labor-intensive creation process. Interestingly, smaller diameter tubes produce brighter neon light, but also have higher resistance. The primary reason for eventual neon tube failure is the slow absorption of neon gas into the glass walls, but even this process can take over 50 years. This extended lifespan makes neon lights ideal for architectural lighting in homes, where they can be shaped to fit tight spaces and provide years of illumination.
Neon sign makers bend heated glass tubes, carefully following a pattern. They use a blow hose to keep the tube's shape and avoid overheating sections. Bends are tricky, requiring quick work before the glass hardens. Mistakes are a pain, potentially forcing a restart. Tubes are welded together, pumped clean, and filled with mercury. Any mistake after filling means scrapping the whole thing, as mercury fumes are dangerous. Completed tubes are connected in series, with proper insulation to prevent damage.
A cold cathodeelectrode is melted (or welded) to each end of the tube as it is finished. The hollow electrodes are also traditionally lead glass and contain a small metal shell with two wires protruding through the glass to which the sign wiring will later be attached. All welds and seals must be leak-proof at high vacuum before proceeding further.
The tube is attached to a manifold which is then attached to a high-quality vacuum pump. The tube is then evacuated of air until it reaches a vacuum level of a few torr. The evacuation is paused, and a high current is forced through the low-pressure air in the tube via the electrodes (in a process known as "bombarding"). This current and voltage is far above the level that occurs in final operation of the tube. The current depends on the specific electrodes used and the diameter of the tube but is typically in the 150mA to 1,500mA range, starting low and increasing towards the end of the process to ensure that the electrodes are adequately heated without melting the glass tube. The bombarding current is provided by a large transformer with an open-circuit voltage of roughly 15,000VAC to 23,000VAC. The bombarding transformer acts as an adjustable constant current source, and the actual voltage during operation depends on the length and pressure of the tube. Typically the operator will maintain the pressure as high as the bombarder will allow to ensure maximum power dissipation and heating. Bombarding transformers may be specially made for this use, or may be repurposed electrical utility distribution transformers (the type seen mounted on utility poles) operated backwards to produce a high voltage output.
This very high power dissipation in the tube heats the glass walls to a temperature of several hundred degrees Celsius, and any dirt and impurities within are drawn off in the gasified form by the vacuum pump. The greatest impurities that are driven off this way are the gases that coat the inside wall of the tubing by adsorption, mainly oxygen, carbon dioxide, and especially water vapor. The current also heats the electrode metal to over 600°C, producing a bright orange incandescent color. The cathodes are prefabricated hollow metal shells with a small opening (sometimes a ceramic donut aperture) which contains in the interior surface of the shell a light dusting of a cold cathode low work function powder (usually a powder ceramic molar eutectic point mixture including BaCO2), combined with other alkaline earth oxides, which reduces to BaO2 when heated to about 500 degrees F, and reduces the work function of the electrode for cathodic emission. Barium Oxide has a work function of roughly 2eV whereas tungsten at room temperature has a work of 4.0eV. This represents the cathode drop or electron energy required to remove electrons from the surface of the cathode. This avoids the necessity of using a hot wire thermoelectric cathode such as is used in conventional fluorescent lamps. And for that reason, neon tubes are extremely long lived when properly processed, in contrast to fluorescent tubing, because there is no wire filament as there is in a fluorescent tube to burn out like a common light bulb. The principal purpose of doing this is to purify the interior of the tube before the tube is sealed off so that when it is operated, these gases and impurities are not driven off and released by the plasma and the heat generated into the sealed tube, which would quickly burn the metal cathodes and mercury droplets (if pumped with argon/mercury) and oxidize the interior gases and cause immediate tube failure. The more thorough the purification of the tube is, the longer lasting and stable the tube will be in actual operation. Once these gases and impurities are liberated under pre-filling bombardment into the tube interior they are quickly evacuated by the pump.
While still attached to the manifold, the tube is allowed to cool while pumping down to the lowest pressure the system can achieve. It is then filled to a low pressure of a few torrs (millimeters of mercury) with one of the noble gases, or a mixture of them, and sometimes a small amount of mercury. This gas fill pressure represents roughly 1/100th of the pressure of the atmosphere. The required pressure depends on the gas used and the diameter of the tube, with optimal values ranging from 6Torr (0.8kPa) (for a long 20mm tube filled with argon/mercury) to 27Torr (3.6kPa) (for a short 8mm diameter tube filled with pure neon). Neon or argon are the most common gases used; krypton, xenon, and helium are used by artists for special purposes but are not used alone in normal signs. A premixed combination of argon and helium is often used in lieu of pure argon when a tube is to be installed in a cold climate, since the helium increases voltage drop (and thus power dissipation), warming the tube to operating temperature faster. Neon glows bright red or reddish orange when lit. When argon or argon/helium is used, a tiny droplet of mercury is added. Argon by itself is very dim pale lavender when lit, but the droplet of mercury fills the tube with mercury vapor when sealed, which then emits ultraviolet light upon electrification. This ultraviolet emission allows finished argon/mercury tubes to glow with a variety of bright colors when the tube has been coated on the interior with ultraviolet-sensitive phosphors after being bent into shape.
An alternative way of processing finished neon tubes has also been used. Because the only purpose of bombardment by electrical means is to purify the interior of tubes, it is also possible to produce a tube by heating the tube externally either with a torch or with an oven, while heating the electrode with a radio frequency induction heating (RFIH) coil. While this is less productive, it creates a cleaner custom tube with significantly less cathode damage, longer life and brilliance, and can produce tubes of very small sizes and diameters, down to 6mm OD. The tube is heated thoroughly under high vacuum without external electrical application, until the outgassed gases can be seen to have been totally depleted and the pressure drops to a high vacuum again. Then the tube is filled, sealed and the mercury dropped and shaken.
The finished glass pieces are illuminated by either a neon sign transformer or a switched-mode power supply, usually running at voltages ranging between 2–15kV and currents between 18 and 30mA (higher currents available on special order.) [27] These power supplies operate as constant-current sources (a high voltage supply with a very high internal impedance), since the tube has a negative characteristic electrical impedance. Standard tube tables established in the early days of neon are still used that specify the gas fill pressures, in either Ne or Hg/Ar, as a function of tube length in feet, tube diameter and transformer voltage.
The standard traditional neon transformer, a magnetic shunt transformer, is a special non-linear type designed to keep the voltage across the tube raised to whatever level is necessary to produce the fixed current needed. The voltage drop of a tube is proportional to length and so the maximum voltage and length of tubing fed from a given transformer is limited. Generally, the loaded voltage drops to about 800VAC at full current. The short-circuit current is about the same.[27]
Compact high frequency inverter-converter transformers developed in the early 1990s are used, especially when low Radio Frequency Interference (RFI) is needed, such as in locations near high-fidelity sound equipment. At the typical frequency of these solid state transformers, the plasma electron-ion recombination time is too long to extinguish and reignite the plasma at each cycle, unlike the case at power line frequency. The plasma does not broadcast high frequency switching noise and remains ionized continually, becoming radio noise free.
The most common current rating is 30 mA for general use, with 60mA used for high-brightness applications like channel letters or architectural lighting. 120mA sources are occasionally seen in illuminating applications, but are uncommon since special electrodes are required to withstand the current, and an accidental shock from a 120mA transformer is much more likely to be fatal than from the lower current supplies.
The efficiency of neon lighting ranges between that of ordinary incandescent lights and that of fluorescent lamps, depending on color. On a per-watt basis, incandescents produce 10 to 20 lumens, while fluorescents produce 50 to 100 lumens. Neon light efficiency ranges from 10 lumens per watt for red, up to 60 lumens for green and blue when these colors result from internal phosphor coatings.[28]
Club Prima Donna animated neon sign in Reno, Nevada, 1955
A highly opaque special black or gray glass paint can be used to "black out" parts of a tube, as between letters of a word. In most mass-produced low-priced signs today, clear glass tubing is coated with translucent paint to produce colored light. In this way, several different colors can be produced inexpensively from a single glowing tube. Over time, elevated temperatures, thermal cycling, or exposure to weather may cause the colored coating to flake off the glass or change its hue. A more expensive alternative is to use high-quality colored glass tubing, which retains a more stable appearance as it ages.
Applications
Light-emitting tubes form colored lines with which a text can be written or a picture drawn, including various decorations, especially in advertising and commercial signage. By programming sequences of switching parts on and off, there are many possibilities for dynamic light patterns that form animated images.
In some applications, neon tubes are increasingly being replaced with LEDs, given the steady advance in LED luminosity [29] and decreasing cost of high-brightness LEDs.[30] However, proponents of neon technology maintain that they still have significant advantages over LEDs.[31]
Neon illumination is valuable to invoke the 1940s or 1950s nostalgia in marketing and in the historic restoration of architectural landmarks from the neon era. Architecture in the streamline moderne era often deployed neon to accent structural pigmented glass built into the façade of a 1930s or 1940s structure; many of these buildings now qualify for inclusion on historic registers such as the U.S. National Register of Historic Places if their historic integrity is faithfully maintained.[32]
An electric light, lamp, or light bulb is an electrical component that produces light. It is the most common form of artificial lighting. Lamps usually have a base made of ceramic, metal, glass, or plastic, which secures the lamp in the socket of a light fixture, which is often called a "lamp" as well. The electrical connection to the socket may be made with a screw-thread base, two metal pins, two metal caps or a bayonet mount.
A Nixie tube, or cold cathode display, is an electronic device used for displaying numerals or other information using glow discharge.
A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet light that then causes a phosphor coating on the inside of the lamp to glow. A fluorescent lamp converts electrical energy into useful light much more efficiently than an incandescent lamp. The typical luminous efficacy of fluorescent lighting systems is 50–100 lumens per watt, several times the efficacy of incandescent bulbs with comparable light output. For comparison, the luminous efficacy of an incandescent bulb may only be 16 lumens per watt.
A cold cathode is a cathode that is not electrically heated by a filament. A cathode may be considered "cold" if it emits more electrons than can be supplied by thermionic emission alone. It is used in gas-discharge lamps, such as neon lamps, discharge tubes, and some types of vacuum tube. The other type of cathode is a hot cathode, which is heated by electric current passing through a filament. A cold cathode does not necessarily operate at a low temperature: it is often heated to its operating temperature by other methods, such as the current passing from the cathode into the gas.
A neon lamp is a miniature gas-discharge lamp. The lamp typically consists of a small glass capsule that contains a mixture of neon and other gases at a low pressure and two electrodes. When sufficient voltage is applied and sufficient current is supplied between the electrodes, the lamp produces an orange glow discharge. The glowing portion in the lamp is a thin region near the cathode; the larger and much longer neon signs are also glow discharges, but they use the positive column which is not present in the ordinary neon lamp. Neon glow lamps were widely used as indicator lamps in the displays of electronic instruments and appliances. They are still sometimes used for their electrical simplicity in high-voltage circuits.
A flashtube (flashlamp) is an electric arc lamp designed to produce extremely intense, incoherent, full-spectrum white light for a very short time. A flashtube is a glass tube with an electrode at each end and is filled with a gas that, when triggered, ionizes and conducts a high-voltage pulse to make light. Flashtubes are used most in photography; they also are used in science, medicine, industry, and entertainment.
A gas-filled tube, also commonly known as a discharge tube or formerly as a Plücker tube, is an arrangement of electrodes in a gas within an insulating, temperature-resistant envelope. Gas-filled tubes exploit phenomena related to electric discharge in gases, and operate by ionizing the gas with an applied voltage sufficient to cause electrical conduction by the underlying phenomena of the Townsend discharge. A gas-discharge lamp is an electric light using a gas-filled tube; these include fluorescent lamps, metal-halide lamps, sodium-vapor lamps, and neon lights. Specialized gas-filled tubes such as krytrons, thyratrons, and ignitrons are used as switching devices in electric devices.
A glow discharge is a plasma formed by the passage of electric current through a gas. It is often created by applying a voltage between two electrodes in a glass tube containing a low-pressure gas. When the voltage exceeds a value called the striking voltage, the gas ionization becomes self-sustaining, and the tube glows with a colored light. The color depends on the gas used.
A plasma ball, plasma globe, or plasma lamp is a clear glass container filled with noble gases, usually a mixture of neon, krypton, and xenon, that has a high-voltage electrode in the center of the container. When voltage is applied, a plasma is formed within the container. Plasma filaments extend from the inner electrode to the outer glass insulator, giving the appearance of multiple constant beams of colored light. Plasma balls were popular as novelty items in the 1980s.
High-intensity discharge lamps are a type of electrical gas-discharge lamp which produces light by means of an electric arc between tungsten electrodes housed inside a translucent or transparent fused quartz or fused alumina arc tube. This tube is filled with noble gas and often also contains suitable metal or metal salts. The noble gas enables the arc's initial strike. Once the arc is started, it heats and evaporates the metallic admixture. Its presence in the arc plasma greatly increases the intensity of visible light produced by the arc for a given power input, as the metals have many emission spectral lines in the visible part of the spectrum. High-intensity discharge lamps are a type of arc lamp.
A Geissler tube is a precursor to modern gas discharge tubes, demonstrating the principles of electrical glow discharge, akin to contemporary neon lights, and central to the discovery of the electron. This device was developed in 1857 by Heinrich Geissler, a German physicist and glassblower. A Geissler tube is composed of a sealed glass cylinder of various shapes, which is partially evacuated and equipped with a metal electrode at each end. It contains rarefied gases—such as neon or argon, air, mercury vapor, or other conductive substances, and sometimes ionizable minerals or metals like sodium. When a high voltage is applied between the electrodes, there is an electric current through the tube, causing gas molecules to ionize by shedding electrons. The free electrons reunite with the ions and the resulting energic atoms emit light via fluorescence, with the emitted color characteristic of the contained material.
A mercury-vapor lamp is a gas-discharge lamp that uses an electric arc through vaporized mercury to produce light. The arc discharge is generally confined to a small fused quartz arc tube mounted within a larger soda lime or borosilicate glass bulb. The outer bulb may be clear or coated with a phosphor; in either case, the outer bulb provides thermal insulation, protection from the ultraviolet radiation the light produces, and a convenient mounting for the fused quartz arc tube.
A metal-halide lamp is an electrical lamp that produces light by an electric arc through a gaseous mixture of vaporized mercury and metal halides. It is a type of high-intensity discharge (HID) gas discharge lamp. Developed in the 1960s, they are similar to mercury vapor lamps, but contain additional metal halide compounds in the quartz arc tube, which improve the efficiency and color rendition of the light. The most common metal halide compound used is sodium iodide. Once the arc tube reaches its running temperature, the sodium dissociates from the iodine, adding orange and reds to the lamp's spectrum from the sodium D line as the metal ionizes. As a result, metal-halide lamps have high luminous efficacy of around 75–100 lumens per watt, which is about twice that of mercury vapor lights and 3 to 5 times that of incandescent lights and produce an intense white light. Lamp life is 6,000 to 15,000 hours. As one of the most efficient sources of high CRI white light, metal halides as of 2005 were the fastest growing segment of the lighting industry. They are used for wide area overhead lighting of commercial, industrial, and public places, such as parking lots, sports arenas, factories, and retail stores, as well as residential security lighting, automotive headlamps and indoor cannabis grow operations.
The induction lamp, electrodeless lamp, or electrodeless induction lamp is a gas-discharge lamp in which an electric or magnetic field transfers the power required to generate light from outside the lamp envelope to the gas inside. This is in contrast to a typical gas discharge lamp that uses internal electrodes connected to the power supply by conductors that pass through the lamp envelope. Eliminating the internal electrodes provides two advantages:
Neon lighting consists of brightly glowing, electrified glass tubes or bulbs that contain rarefied neon or other gases. Neon lights are a type of cold cathode gas-discharge light. A neon tube is a sealed glass tube with a metal electrode at each end, filled with one of a number of gases at low pressure. A high potential of several thousand volts applied to the electrodes ionizes the gas in the tube, causing it to emit colored light. The color of the light depends on the gas in the tube. Neon lights were named for neon, a noble gas which gives off a popular orange light, but other gases and chemicals called phosphors are used to produce other colors, such as hydrogen (purple-red), helium, carbon dioxide (white), and mercury (blue). Neon tubes can be fabricated in curving artistic shapes, to form letters or pictures. They are mainly used to make dramatic, multicolored glowing signage for advertising, called neon signs, which were popular from the 1920s to 1960s and again in the 1980s.
Gas-discharge lamps are a family of artificial light sources that generate light by sending an electric discharge through an ionized gas, a plasma.
Tanning lamps are the part of a tanning bed, booth or other tanning device which produces ultraviolet light used for indoor tanning. There are hundreds of different kinds of tanning lamps most of which can be classified in two basic groups: low pressure and high pressure. Within the industry, it is common to call high-pressure units "bulbs" and low-pressure units "lamps", although there are many exceptions and not everyone follows this example. This is likely due to the size of the unit, rather than the type. Both types require an oxygen free environment inside the lamp.
Large-screen television technology developed rapidly in the late 1990s and 2000s. Prior to the development of thin-screen technologies, rear-projection television was standard for larger displays, and jumbotron, a non-projection video display technology, was used at stadiums and concerts. Various thin-screen technologies are being developed, but only liquid crystal display (LCD), plasma display (PDP) and Digital Light Processing (DLP) have been publicly released. Recent technologies like organic light-emitting diode (OLED) as well as not-yet-released technologies like surface-conduction electron-emitter display (SED) or field emission display (FED) are in development to supercede earlier flat-screen technologies in picture quality.
A crackle tube is a type of plasma lamp that is used most commonly in museums, night clubs, movie sets, and other applications where its appearance may be appealing for entertainment. Such a device consists of a double walled glass tube with a hollow center. The cavity between the inner and outer glass tubes is filled with thousands of small phosphor coated glass beads. A 5–14 kV transformer produces a low power gas discharge in the bead filled cavity, producing filaments of light that simulate lightning. Crackle tubes get their name not because of the sound they produce but rather because of the appearance of their internal behavior. The "lightning" is forced around and in between the phosphor-coated glass beads, due to the beads' dielectric nature. In so doing, the phosphor is excited by the electrical energy and fluoresces producing visible light. Like plasma globes, crackle tubes respond to touch; the filaments appear to be "attracted" toward the point of contact and usually become more luminous (brighter) as the electricity is grounded. The tubes are also filled with a noble gas like neon, argon, or xenon which acts as the electron transfer medium of the cavity. The gas is typically below atmospheric pressure.
Plasma lamps are a type of electrodeless gas-discharge lamp energized by radio frequency (RF) power. They are distinct from the novelty plasma lamps that were popular in the 1980s.
1 2 Bright, Arthur A. Jr. (1949). The Electric-Lamp Industry. MacMillan. Pages 221–223 describe Moore tubes. Pages 369–374 describe neon tube lighting. Page 385 discusses Risler's contributions to fluorescent coatings in the 1920s. Pages 388–391 discuss the development of the commercial fluorescent at General Electric in the 1930s.
↑ These anecdotes and the phrase "liquid fire" are often used in references discussing the first neon tube lights in Los Angeles, but the primary source is not provided. One example of a typical, tertiary reference is Bellis, Mary. "The History of Neon Signs: Georges Claude and Liquid Fire". ThoughtCo.
↑ Strattman, Wayne (1997). Neon Techniques: Handbook of Neon Sign and Cold-Cathode Lighting, 4th edition. ST Media Group International. ISBN978-0-944094-27-3.
Crowley, David (September 2007). "Life in the Darkness". Creative Review. Retrieved 2021-10-11. Article about neon signage's flowering and decline in Warsaw and Poland.
Strattman, Wayne (1997). Neon Techniques: Handbook of Neon Sign and Cold-Cathode Lighting, 4th edition. ST Media Group International. ISBN978-0-944094-27-3. – industry standard reference on practices, methods, and technologies used by neon fabricators
External links
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