Illumination Basics Means of gas (usually argon). The elec- Century. Neon tubing consists Illumination trodes at either end of the tube of two types: (1) hot cathode, set off a reaction that leads to electric-discharge tube, as in flu- The earliest form of electrical the release of ultraviolet light. orescent lighting, and (2) cold sign illumination utilized incan- That invisible light subsequently cathode, electric-discharge light- descent lamps, and they are still sets off a reaction in the phos- ing – commonly referred to as widely used. Incandescent light phor powder coating inside the “neon,” but which frequently is produced through the applica- tube, which then emits a visible employs other inert gases (e.g., tion of electrical energy to a light. The color of the light can helium, argon, krypton, or wire filament, which glows as it be changed by altering the com- xenon). Luminous tubing, par- is heated. Because it is nearly a bination of phosphors coating ticularly neon signage, has point source light, it is not easily the tube. This lighting gets its undergone a renaissance, and is diffused. Incandescent lamps name because the phosphor increasingly utilized for either are available in a broad range of “fluoresces” when energized. individual façade or business colors and brilliance, and gener- The light output per square foot district renovations. Its major ally possess optimum visibility of a number of different colors drawbacks are that it is not as and legibility characteristics. of 12 mm. fluorescent tubing at effective as other types of signs They can be mass produced. 25 ma. (milliamperes) is shown during the day, and can be on Table 6. This is the most expensive to install. Fluorescent light is produced popular size used in neon sign through a more complicated, but work. The “neon” tube sign is general- also more efficient, process than ly designed to form connected incandescent light. A fluores- Another common form of light- letters, individual letters, parts cent tube contains a small ing is luminous tubing, first per- of letters, skeleton tubing, out- amount of mercury and an inert fected in the early Twentieth line lighting, and decorative ele- Luminous tubing, particularly so- called “neon” signage, has undergone a renaissance, and is increasingly utilized for either individual facade or business dis- trict renovations. The Signage Sourcebook Page 90 wide range of colors. Krypton not yet, however, a practical or TABLE 6 produces a lilac shade when proven technology for all sig- TABLE 7 Light Output of 12 mm Fluorescent Sign Tubing charged; helium, a white or yel- nage and lighting applications. Means of Illumination Operated at 25 ma. (30 ma. Transformer) lowish light; and xenon, a blue for Luminous Source Message Signs glow (these are seldom used in Comparison of Color Number Color Name Approx. Candelas sign applications). Because it Efficacy of LEDs and Electric Discharge Tubing – “Neon” per Sq. Foot uses a cold cathode technology, Neon - Easily shaped to conform with message contours “neon” signage can operate for -Wide variety of color 10 Deep Red 2 many years, and is highly effi- - Fairly high light output per energy used 20 Yellow Gold* 32 In December, 2002, Signs of the cient, e.g., a pure neon tube - Not as effective as other types of signs in daytime 30 Cream White 50 Times, a magazine oriented to radiates five times as much red - Expensive to install 31 Warm White 45 sign manufacturers, ran an article light for a given amount of 32 Daylight* 40 entitled, “Neon Is Here, and power as does an incandescent Light Emitting Diodes – “LEDs” 33 Pink White 32 LEDs Step Up to the Plate,” by lamp.1 - New, rapidly improving technology George Doll. The article made a 34 3500 K White 45 - Solid state technology – widely used for traffic signals number of comparisons between 35 Soft White 35 A rapidly evolving lighting tech- and message centers the up-and-coming LED technol- 36 4500 K White 43 nology is that of light emitting - Narrow beam distribution ogy and neon lighting.2 40 Green* 80 diodes (LED), which hold great -Wide variety of colors, but some colors expensive and of 40 Amber Gold* 30 promise for certain applications. low efficacy One question the article asked 41 Deep Green 27 These tiny bulbs, unlike incan- - Long life after initial drop in output was whether “LEDs operate with 50 Blue* 25 descent bulbs, do not contain fil- - Sensitive to high temperatures superior efficacy at equivalent 50 Rose Pink* 22 aments, and they do not get hot. luminance compared to neon- 51 Deep Blue 6 Illumination results from the type light sources (regardless of movement of electrons in a color and power supply type)?” Table 8 compares the efficacy of As indicated in the comparison, *National Electric Sign Association Standard Colors semiconductor material. According to the Illuminating red LEDs running on a ferro- red LEDs’ system efficacy of Increased efficiency and innova- Engineering Society of North magnetic power supply to that of 22.5 lm/W are slightly (25%) ments or art forms, in various clear glass. Argon produces a tion are certainly possible in America, “efficacy” is the quo- neon filled clear-glass tubing more efficacious than neon oper- colors and diameters. Channel weak blue light, and is used in time, and great strides are being tient, expressed in lumens per running on a solid-state power ating on a solid state transformer letters into which neon tubes are combination with mercury vapor made in the areas of high-output watt (lm/W), of the total lumi- supply. It assumes the follow- (18 lm/W), and somewhat more fitted provide excellent defini- to produce ultraviolet light, phosphors, solid-state power nous flux emitted, divided by the ing: (54%) efficacious than neon tion and legibility. Neon’s color which then excites the phospho- supplies and extended lamp life total lamp power input. In the operating on ferromagnetic trans- is orange-red, also known as rous coating on the inside of the through better processing tech- following comparison, “system -A5-ft. (1.5 meter)-high chan- formers (14 lm/W). The com- “clear red” when seen through tube to produce visible light in a niques and education. LEDs are efficacy” provides a more accu- nel letter with an acrylic face parison demonstrates that “supe- rate comparison between the two (Cyro 278-0, for example); rior efficacy” at equivalent lumi- types of illumination because it - Five neon tubes, 5 ft. (1.5 nance for “red” LEDs, compared The latest lighting accounts for all the power uti- meters) long, 15mm diameter, to “red” neon, particularly those technology is utilized lized by each type, accounting totaling 25 ft. (7.6 meters); operating on solid-state trans- in tourist-oriented for losses incurred in their - 9kV transformers, 30mA fer- formers, is insufficient to justify areas such as Las respective power supplies. It is romagnetic and 35mA solid- the re-lamping of existing red Vegas to delight the calculated by dividing total state; and signs or a legislative mandate public and promote lumen output of the light source - Lumens and watts per LED effectively banning neon as an business activity by the input power of the power are derived from industry illuminating source for channel after dark. source driving that light source. charts. letters. Additionally, actual oper- 1. Miller, Samuel c. Neon Signs and Cold Cathode Lighting. Tubelite Co., Inc. 1963. 2. It should be noted that LED technology is advancing extremely rapidly, and any data that could be included in this manual is likely already out of date. Between mid-2002 and mid-2003, 50% to 100% gains in efficacy were not uncommon. 3. Lumens cannot be reliably converted to candelas because lumens and candelas are measurements of very different effects. Lumens (Luminous Flux) is the total energy emitted by a light source, weighted by the human eye response. Candelas (Luminous Intensity) is the lumens emitted into a specific (usually very small) solid angle at a specified angular orientation. Page 92 ating measurements have proven neon, and indicates that claims not possible. dramatically different depending than green LEDs. applications, such as small chan- to be much less impressive than of “demand reduction and energy on the color compared. Not all nel letters containing a single the industry charts and may savings in the range of 80-90%” The comparison of the efficacy neon signs are red. Table 9 In an effort to reduce energy row of LEDs with one driver, it move LEDs down to the level of at “equivalent luminance” are of neon systems and LEDs is compares the efficacies of green consumption, some have sug- is generally impossible to switch LEDs running on a ferromagnet- gested that during early morning off 50% of the LEDs. In larger ic power supply and green, hours 50% of the LEDs should applications with multiple rows phosphorous coated neon-filled be switched off or that the entire of LEDs and multiple drivers, TABLE 8 glass tubing, running on a solid- unit should be dimmed by 50%. the message would be rendered Red LED vs. Red Neon state power supply. It shows But LEDs are typically run in unsightly at best and quite possi- The numbers in each chart are slightly skewed against neon. In the neon-related measurements, that neon-driven applications are series and are often “pre-wired” bly unreadable due to dark power losses in the ferromagnetic transformers and electronic power supplies were calculated. substantially more efficacious to run that way. In “single-run” patches in the midst of the mes- These numbers are not available regarding LEDs because no standard has been established for these converters.