Illumination Basics

Means of gas (usually ). The elec- Century. tubing consists Illumination trodes at either end of the tube of two types: (1) hot , set off a reaction that leads to electric-discharge tube, as in flu- The earliest form of electrical the release of . orescent , 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 , argon, , 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 coating ticularly neon , 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 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 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 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 for all sig- TABLE 7 Light Output of 12 mm Fluorescent Sign Tubing charged; helium, a or yel- nage and lighting applications. Means of Illumination Operated at 25 ma. (30 ma. ) lowish light; and xenon, a 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 technology, Neon - Easily shaped to conform with message contours “neon” signage can operate for -Wide variety of color 10 Deep 2 many years, and is highly effi- - Fairly high light output per energy used 20 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 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 .2 40 * 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 . 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 -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 , 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.

(1) Red LED TABLE 9 Assume: GEL Core LED modules Lumens/Watt, Green LED vs. Green Luminous Tubing -3 lumens per module - 0.12W per module (1) Green LED - 500 LED modules - 2.5 lumens each - 90% system efficiency (accounts for losses in power supply) - 0.12W each - 2,400 LED modules Calculate: 500 modules x 0.12W/module = 60W - 6,000 lumens - 500 modules x 3 lumens per module = 1,500 lumens - 90% system efficiency - 1,500 lumens/60W = 25 lm/W (at the lamp) - 25 lm/W x90% = 22.5 lm/W (system efficacy) Calculation: - 2,400 LED modules x 0.12W per module = 288W -Total input power = 288/0.9 = 320W (this accounts for losses in power supply) (2) Red Neon on Neon Transformers and Solid-state Transformers - System efficacy = 6,000/320 = 18.8 lm/W Input power, output current and relative light output were made on 25 ft. (7.6 meters) of 15mm red neon powered by: -9 kV, 30mA ferromagnetic transformer (2) Green Luminous Tubing -9 kV, 35mA solid-state transformer - Powered by 7,500V, 30mA ferromagnetic transformer - 25 ft. (7.6 meters) of 15mm tubing The results were as follows: - 6,000 lumens by industry tubing charts (787 lumens/meter, or 240 lumens/ft.) when operat- ed on a ferromagnetic transformer Ferromagnetic Transformer: - Input power = 102W Actual Measurements: - Output current = 24.6mA - Input power = 83.6W - Relative light output = 133 (assume this number represents 1,500 lumens per tubing-chart - System efficacy = 6,000/83.6 = 71.8 lm/W predictions) -Yields a system efficacy of 1,500/102 or 14.7 lm/W (3) Green Luminous Tubing Solid-state Transformer: - Powered by 7,500V, 35mA solid-state transformer - Input power = 76.6W - 25 ft. (7.6 meters) of 15mm tubing - Output current = 30.8mA - Produces 5,503 lumens (by relative measurement method used in Table 7) - Relative Light output = 122 - Because a relative light output of 133 represents 1,500 lumens, then a relative light output of Actual Measurements: 122 = 122/133 x 1,500 or 1,376 lumens - Input power = 62.5W -Yields a system efficacy of 1,376/76.6 or 18 lm/W - System efficacy = 5,503/62.5 = 88 lm/W

Illumination Basics Page 94 sage were 50% of the tion of the light output of exist- them to the color of the translu- switched off. Furthermore, the ing neon signs, reducing light cent filter. Then again, neon TABLE 10 message may well become vir- output to an unacceptable level. lamps are far less monochromat- Comparisons of Watts per Meter (W/m) tually unreadable if dimmed by In some cases, LEDs would ic than LEDs, regarding spectral 50% due to the relatively low actually increase energy costs, distribution, yet they clearly Red Neon Tube light output of LEDs. however, and in every case the exceed the lumen output of - 15,000V, 30mA ferromagnetic LEDs have much higher instal- LEDs behind faces. - 60 feet (18.3 meters), 15mm clear tubing Table 10 shows lamp watts per lation costs. Green LEDs at Also, although monochromatic meter calculations. equivalent luminance are 48 in nature, LEDs are designed as Measured: times as expensive as neon, highly directional light sources. - Input power = 210W Table 11 shows two examples of excluding power supplies. They are nestled in a reflector Calculation: input draw, or how many watts cup, placed directly below the - 210/60 = 3.5W/foot (210/18.3 = 11.5W/meter) per meter are consumed with Some have suggested the mono- semiconductor, in conjunction LED illumination compared to chromatic nature of with an epoxy dome, A 15,000V, 30mA transformer will run 60 feet (18.3 meters) of 15mm neon-filled tubing. neon illumination. Significant LEDs allows light Many signs as a focusing lens. energy savings is possible with loss to be mini- creatively Light output could the use of LEDs, but at a frac- mized by matching be dramatically incorporate Argon/Mercury Tube more than one - 15,000V 30mA ferromagnetic form of lighting - 72 feet (22 meters), 15mm coated tubing technology. Measured: - Input power = 209W Calculation: - 209/72 = 2.9W/foot (209/22 = 9.5W/meter)

A 15,000V, 30mA transformer will run 72 feet (22 meters) of argon/mercury-filled tubing (40ºF or above).

Red Neon Tube - 9,000V, 35mA solid-state - 33.5 feet (10.2 meters), 15mm clear tubing

Measured: - Input power = 86.7W Calculation: - 86.7/33.5 = 2.6W/foot (86.7/10.2 = 8.5W/meter)

Argon/Mercury Tube - 9,000V, 35mA solid-state - 44 feet (13.4 meters), 15mm clear tubing

Measured: - Input power 92.3W Calculation: - 92.3/44 = 2.1W/foot (92.3/13.4 = 6.9W/meter)

Page 96 reduced if the LEDs are mis- ing is lamp life. At present, no to burn out. LED lamp life is rent, according to many public signs aligned with the channel letter proper definition of LED lamp defined as the time taken for the research published by along streets and high- face, due to adhesive failure or life exists because half-life, oper- light output to reach 50% of its The Lighting Research ways. sloppy installation. ating current and color have not original value. 5mm white Center of Rensselaer been factored in. For traditional LEDs can reach 50% of original Institute (Troy, NY). Floodlighting as a An important factor in the com- light sources, lamp life is the value in less than 10,000 hours method of illumination parison of LED and neon light- time it takes for 50% of samples running on as little as 20mA cur- LED proponents fre- occurs when an exter- quently claim 100,000- nal light source, either hour life for red LEDs, incandescent, metal TABLE 11 based on an operating halide, or fluorescent, Sample Calculations of Lumens per Meter current of 20-30mA. If Floodlighting as a method of illumination is aimed at the sign used to replace existing occurs when an external light source, face. On-premise signs Example 1 neon signs, operating either incandescent, metal halide, or that utilize floodlight- current must be fluorescent, is aimed at the sign face. ing tend to be either Red Neon Tube increased significantly if painted wall signs or Using “clear red” 15mm tubing @ 30mA and 60 lm/ft (198 lm/m) as the equivalent luminance “equivalent luminance” high-rise freestanding is to be achieved, or nificantly and adversely impact signs. The widespread Red LEDs more LEDs must be added. LEDs’ projected life, including use of floodlighting in very tall - Red LEDs at 3 lumens per LED operating at 30mA and 0.12W each Depending on the increase in moisture, electrolysis, improper freestanding signs is tied to current, LED life could fall far driver adjustment, incorrect maintenance, which is much To achieve an “equivalent luminance” of 198 lm/m., one would need: short of the 100,000-hour pro- polarity, static electricity and easier when the lamps are acces- - 20 LEDs per ft. (20 LEDs at 3 lumens each = 60 lm/ft.) jection. improper installation. sible from the ground because a OR 66 LEDs per meter (66 LEDs at 3 lumens each = 198 lm/m)* service person is not required to - 20 LEDs at 0.12 watts each = 2.4W/ft. LED manufacturers recommend Methods of scale the sign in order to replace OR 66 LEDs at 0.12 watts each = 7.92W/m against overdriving LEDs to Illumination burnt-out or malfunctioning increase light output. They light sources. *At $3 each, this would equal $60 per ft. ($198 per meter), compared to $5 per ft. ($16.50 per require a current-control system Due to rapidly advancing tech- meter) for neon (excluding power supplies). This is 12 times as expensive as neon. to operate. Higher current nology, a wide variety of light- The silhouette sign utilizes a increases the LEDs’ operating ing techniques are available. form of floodlighting, though it temperature, as well as energy Sign illumination may be by is illuminated from behind so Example 2 costs. Once a certain tempera- means of: that the letters stand out darkly ture threshold in the LED pack- against the sign. Typically, this Argon/Mercury Tube age is reached, performance 1. A light behind the sign face, sign is created by luminous tub- Using 15mm green luminous tubing @ 30mA and 787 lm/m as the equivalent luminance drops dramatically. Light output illuminating the main message ing concealed behind opaque begins to decrease, and the loss or symbol, or the sign back- letters or behind a valance or Green LEDs is permanent, thus dramatically ground, or both, through a cornice. When properly done, - Green LEDs @ 2.5 lumens per LED operating @ 30mA/1.2W each reducing their useful life. translucent material; these signs can be highly strik- Furthermore, a high pulse of 2. An attached or independently ing. However, care must be To achieve an equivalent luminance of 787 lm/m, one would need: current can actually melt the mounted light source designed taken to avoid distracting shad- - 96 LEDs per ft. (96 LEDs @ 2.5 lumens each = 240 lm/ft.) wedge-wire bond in an LED, to direct essential uniform illu- ows or reflections, or to assure OR 315 LEDs per meter (315 LEDs @ 2.5 lumens each = 787 lm/m)* causing instant and irreversible mination over the entire face of that halation (when light, due to - 96 LEDs @ 0.12W each – 11.52 W/ft. failure. the sign; background reflection and illu- OR 315 LEDs @ 0.12W each = 37.8W/m 3. Luminous tubing or fiber mination, spreads beyond its LEDs’ projected life may also optics, patterns of incandescent proper boundary, resulting in *At $4 each, this would equal $384 per ft. ($1,260 per meter) to achieve “equivalent luminance” be greatly reduced in high ambi- light bulbs, or light emitting blurring of the image or text) compared to roughly $8 per foot ($26.25 per meter) for green luminous tubing (excluding power ent temperatures (above 130º), diodes shaped or formed in pat- does not degrade legibility. supplies) or 48 times as expensive as neon. This is also assuming that one could actually pack 96 common in channel letters, par- terns of lettering or symbols; or Finely detailed letters or script LEDs per foot (315 LEDs per meter) into a channel letter. Green LEDs operate at 11.52W/ft. (37.8 ticularly in warmer climates. 4. Retroreflective materials, often become blurred when illu- W/m.) to achieve the equivalent luminance of neon. Many other factors also can sig- such as materials appearing on minated from behind by a strong

Illumination Basics Page 98 light, especially when viewed and react appropriately, there- from a great distance. by increasing traffic safety. TABLE 12 Means of Illumination for Floodlighting Externally Illuminated Signs People often do not realize Exceptional visibility is how important the location of accompanied by exceptional Incandescent light fixtures is for readability. versatility, due to the sign’s - Old technology/widely used Fixtures located above or automated dimming and focus- - Low light output per energy used beside a sign face can cast a ing systems which make it - Ease to control and keep light on sign shadow over the sign during possible for it to respond near- - Short life – 750 to 8000 hours part of the day, obscuring the ly instantaneously to any message. change in or Metal Halide visibility needs. - White light source The Electronic - High light output per energy used Message Center Advances in LED, LCD, and The local airport in - Easier to control beam pattern than incandescent computer technology are rev- Monmouth, NJ offers a clear - Long life – 7500 to 24,000 hours LED and liquid crystal display olutionizing the sign industry. example of EMC versatility. (LCD) technology combined The airport uses its device to Fluorescent with computer technology advertise price specials at peak - White or a wide range of colored light sources developed during the last 25 variable electronic message cen- commuter hours. During other - Linear source with uniform light output years, and exploding within the ter (EMC). hours, the airport changes the - Long life – 7500 to 12,000 hours last 3-5 years, has begun to rev- display to offer community serv- -Temperature problems in cold weather olutionize the sign industry – The colors most often used in ice messages. This kind of flex- - Hard for maintenance personnel to install, especially from a ladder much as “” did in the EMCs are either red or ibility permits coordination with 1950’s. This techno-combo has yellow/amber letters on darker traffic profiles and times of day, made it possible to produce backgrounds (most often and with video quality message and “black”), making them optimal- visibility/legibility/readability TABLE 13 graphics displays that are com- ly legible and readable, especial- variables such as weather Means of Illumination for Internally Illuminated Signs puter controlled to change at ly under poor lighting condi- changes. designated intervals. The most tions (generally caused by Fluorescent familiar of these signs, and uti- inclement weather). This One disadvantage of the EMC is - Linear source with uniform light output lized by state departments of enhanced legibility also gives a its expense. However, recent - Easier to lay out to get uniform sign face transportation for years, is the motorist additional time to read technological breakthroughs - Uniform control by depth of lamp placement - Long life – 7500 to 12,000 hours -Available in white and wide range of colors Recent break- throughs in elec- tronics technology have drastically reduced produc- cal labor involved in chang- have drastically tion and operating costs, bring- ing copy on the typical reduced production ing it into an affordable range. readerboard; and operating And even though the EMC may b. It has a long life expectancy costs of EMCs, still require a greater initial with minimal bulb or LED bringing them into investment than nearly any other replacement; and an affordable range on-premise sign, it offers many c. For an average sign, the cost for many small advantages: of electricity consumption is businesses. approximately $0.20 per day, a. It allows frequent change of or $74.00 per year. copy without the cost of replacing missing or broken letters, and without the physi-

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