The Characteristics of Incandescent Lamps
Incandescent light is the most commonly used electric light source in the home, which means that people consider it to be “normal.” The low color temperature and high CRI of incandescent lighting casts a warm light which provides excellent color rendition of human skin tones. In addition, incandescent lamps are affordable, can be controlled by inexpensive dimming circuits, and are available in a wide range of sizes, configurations and wattages. Unfortunately, incandescent lamps are inefficient. Because they produce light by heating a solid material until it glows, most of the energy they consume is given off as heat, resulting in low LPW performance. Other more energy efficient lamp types can therefore offer substantially lower operating costs.
Halogen–Superior Incandescent Technology
Tungsten halogen lamps are a refinement of incandescent technology that offer up to 20 percent greater energy efficiency, longer service life and improved light quality. In a standard incandescent lamp, tungsten from the filament evaporates over time and is deposited on the walls of the bulb, thus reducing light output. The filament gets thinner and thinner and eventually breaks, causing the lamp to fail. The halogen gas inside a halogen lamp causes the evaporated tungsten to redeposit on the filament. This process, along with high pressure inside the capsule, slows down deterioration of the filament, improves lumen maintenance and extends the lamp’s service life.
Whiter, Brighter Light
Halogen lamps have higher color temperatures than standard incandescent lamps—their light output contains more blue and green. Halogen lamps therefore appear whiter and brighter. Although both types of lamp essentially have a CRI of 100, the higher color temperature of halogen lamps provides more pleasing and vibrant color rendition across a wider range of colors.
Low Voltage– an Almost Perfect Point Source
Special halogen lamps are available for low voltage configurations and they offer a number of advantages. Low voltage systems, which can be designed to operate efficiently at lower wattages than line voltage systems, allow the use of lamps that are extremely compact and still provide high lumen output. The relatively short, thick filaments in MR16 and MR11 halogen lamps, for example, produce large amounts of light from a very small area and permit excellent beam control. Low voltage halogen lamps have therefore become the preferred choice for accent, display and decor lighting.
A Wide Range of Lamp Shapes
Halogen lamps are available in many sizes, shapes and wattages. Reflector types include PAR, AR and MR configurations in a wide range of wattages and beam angles, from narrow spot to wide flood. Midbreak versions provide long lasting, energy efficient alternatives to standard incandescent lamps. Other lamp configurations allow lighting fixture designers to take full advantage of the special attributes that halogen technology offers.
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Fluorescent Technology
How Fluorescent Lamps Work
A fluorescent lamp is a “gaseous discharge” light source. Light is produced by passing an electric arc between tungsten cathodes in a tube filled with a low pressure mercury vapor and other gases. The arc excites the mercury vapor which generates radiant energy, primarily in the ultraviolet range. This energy causes the phosphor coating on the inside of the tube to “fluoresce,” converting the ultraviolet into visible light. Fluorescent lamps have two electrical requirements. To start the lamp, a high voltage surge is needed to establish an arc in the mercury vapor. Once the lamp is started, the gas offers a decreasing amount of resistance, which means that current must be regulated to match this drop. Otherwise, the lamp would draw more and more power and rapidly burn itself out. This is why fluorescent lamps—and other discharge light sources—must be operated by a ballast, which provides the required starting voltage and then controls the subsequent flow of current to the lamp.
The Importance of Phosphor Coatings
Fluorescent lamps offer more color options than any other lamp type. This is because of sophisticated refinements in the composition of the phosphor coating on the inside of the tube. Early fluorescent lamps used a single halophosphor coating and could offer improved color quality only with an accompanying decrease in efficacy (LPW). It is now possible to add “rare earth” or “triphosphor” coatings that allow precise control over the generation of red, green and blue, the three primary colors of light. This has enabled the development of high LPW lamps in a variety of color temperatures that feature excellent color quality and provide vibrant and outstanding rendition of virtually all colors. Today’s OSRAM SYLVANIA fluorescent lamps employ more than twenty different phosphor formulations to offer designers and specifiers extensive control over the quality of light in any installation.
A Systems Approach
It is always important to bear in mind that fluorescent lighting is a system involving both ballasts and lamps. A properly balanced fluorescent lamp/ballast system enhances luminous efficacy, improves color characteristics, extends lamp life and increases energy efficiency. OSRAM SYLVANIA offers a complete line of System Solution™ lamp/ballast combinations that are specially designed to optimize overall system performance.
T8 Lamps Improve Efficiency
Another important advance in fluorescent technology is the development of the T8 lamp. Featuring a tube of only one inch in diameter— compared with one and a half inches for the traditional T12 lamps—these lamps dramatically improve system efficiency. A 32-watt OCTRON® T8 lamp, for example, uses 20 percent less energy to provide the same light output as a 40- watt T12 lamp. T8 lamps employ special triphosphor coatings to achieve precise control over color temperature and CRI. The smaller diameter of the T8 tube means that less of these costly materials are needed. In addition, T8 lamps provide optimum system efficiency when used with electronic ballasts. This combination provides such dramatic savings in energy costs that billions of dollars are being spent each year to retrofit existing T12 installations with more efficient T8 technology.
T5 Lamps Extend Options
Fluorescent lamps are getting thinner. Although T8 OCTRON lamps are still the choice for retrofitting most T12 installations and for new commercial construction, the new T5 PENTRON® lamp are inspiring the work of lighting specifiers everywhere. PENTRON® SYSTEM PS and SYSTEM PHO are lamp/ballast innovations that are designed to maximize the system performance of T5 lamps. The narrow PENTRON® lamps and slim, lightweight QUICKTRONIC® ballasts allow fixture manufacturers to design T5 luminaires that are both small and stylish.
Compact Fluorescent Lamps Save Energy
The fastest growing application for fluorescent technology today is compact fluorescent lamps. These lamps feature a narrow tube (1/2 to 5/8 inches in diameter) that is doubled back on itself and terminated in a plastic base. Compact fluorescent lamps are small enough to replace incandescent lamps in diffuse source applications and therefore bring the increased efficiency of fluorescent technology to a much larger variety of fixtures. DULUX® EL compact fluorescent lamps, for example, feature an integral electronic ballast and a standard screw-in medium base. These innovative lamps can be used to directly replace incandescent lamps in many of the most common wattages. Other DULUX lamps are available in a variety of sizes, wattages and color temperatures for use with external magnetic or electronic ballasts.
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HID Technology
How HID Technology Works
The technology in high intensity discharge lighting is in some ways similar to fluorescent technology: an arc is established between two electrodes in a gas-filled tube which causes a metallic vapor to produce radiant energy. In this case, however, a combination of factors shifts the wavelength of much of this energy to within the visible range, so light is produced without any phosphors. In addition, the electrodes are only a few inches apart (at opposite ends of a sealed “arc tube”) and the gases in the tube are highly pressurized. This allows the arc to generate extremely high temperatures, causing metallic elements within the gas atmosphere to vaporize and release large amounts of visible radiant energy. There are three main types of HID lamps: mercury vapor, metal halide and sodium. The names refer to the elements that are added to the gases in the arc stream which cause each type to have somewhat different color characteristics and overall lamp efficiency.
Ballasts and Warm-Up Time
Like any gaseous discharge light source, HID lamps have special electrical requirements that must be supplied by a ballast. With HID sources, however, the ballast must be specifically designed for the lamp type and wattage being used. In addition, HID lamps require a warm-up period to achieve full light output. Even a momentary loss of power can cause the system to restrike and have to warm up again—a process that can take several minutes. In applications where constant illumination is important for safety and security, a backup system is often required. The LUMALUX® Standby lamp offers instant restrike capabilities once power is restored, making it an ideal choice for applications where safety is a concern.
Metal Halide Lamps
Metal halide lamps, such as the SYLVANIA METALARC® products, are among the most energy efficient sources of white light available today. These lamps feature special chemical compounds known as “halides” that produce light in most regions of the spectrum. They offer high efficacy, excellent color rendition, long service life and good lumen maintenance. Because of their numerous advantages, metal halide lamps are used extensively in outdoor applications and in commercial interiors. Recently, a wide range of low wattage METALARC® lamps has been developed, offering high performance in a more compact size and bringing HID benefits to applications such as retail and display lighting. There is also an entire family of metal halide lamps called METALARC® Ceramic that employs ceramic arc tube technology to improve color rendition and consistency. METALARC PRO-TECH® lamps represent an additional innovation, featuring a special shroud that surrounds the arc tube, enabling use in open fixtures.
Sodium Lamps
High-pressure sodium sources, such as SYLVANIA’s LUMALUX® lamps, were developed primarily for their energy efficiency. Mercury and sodium vapors in the ceramic arc tube produce a yellow/orange light with extremely high LPW performance and exceptionally long service life (up to 40,000 hours). High-pressure sodium lamps render colors poorly, which tends to limit their use to outdoor and industrial applications where high efficacy and long life are priorities. Variations within the LUMALUX family of lamps include a Standby version with 2 arc tubes for rapid re-strike after power interruption. LUMALUX PLUS® ECO® eliminates cycling at end-of-life. Low pressure sodium sources, are also available. Since these lamps produce light at only one wavelength in the yellow region of the spectrum, they are used where energy efficiency and long life are the only requirements.
Mercury Vapor Lamps
Mercury vapor lighting is the oldest HID technology. The mercury arc produces a bluish light that renders colors poorly. Therefore, most mercury vapor lamps have a phosphor coating that alters the color temperature and improves color rendering to some extent. Other HID types that offer higher LPW and better color properties have largely superceded the use of this
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Lighting Innovations
Inductively Coupled Electrodeless Electronic Lighting Systems
In a recent technological breakthrough, OSRAM SYLVANIA engineers developed a way to produce light without filaments or electrodes. The implications for lighting are profound, as filament and electrode decay limits the life of incandescent, halogen, fluorescent and HID sources. The new lighting system, ICETRON®, combines fluorescent lighting and magnetic induction technology to produce a lamp with a stunning 100,000-hour average rated life. In typical applications, this may translate to a service life as long as 25 years. The ICETRON® system operates much like a traditional fluorescent system, but uses an electronic ballast and ferrite magnets to induce current flow inside the lamp from outside the bulb wall. With its advanced triphosphor lamp coating, the system offers high lumen output, efficiency and color rendering – with essentially no lamp components to
wear out.
Beating the Heat with Infrared-Conserving Halogen Lamps
Much of the energy consumed by incandescent or halogen lamps is wasted as radiated heat. In response to this problem, OSRAM SYLVANIA has developed a tungsten halogen lamp technology that "recycles" infrared energy from the filament, and dramatically increases lamp efficiency. CAPSYLITE IR® and TRU-AIM® IR lamps feature an ellipsoidal halogen capsule with a multilayered, infrared conserving coating. Together, the capsule shape and IR coating reflect radiated heat back onto the filament, while transmitting visible light. Because the heat is reflected back to the filament, less energy is required to maintain the filament at its optimal operating temperature. The results are lower wattage lamps producing as much light as their higher wattage counterparts – a 50W IR-conserving lamp that replaces a 75W standard halogen lamp, for example.
HID Arc Tube Design – Simple is Better
With the advent of ceramic arc tube technology, metal halide lamps have improved significantly in terms of color rendering, lumen maintenance, and color appearance. OSRAM SYLVANIA has taken ceramic arc tubes to the next level with a unique two-piece arc tube design having a rounded geometry. Traditional ceramic arc tubes are cylindrical in shape and are constructed by assembling three or five separate pieces. Fewer pieces means fewer sealing points and reduced potential for arc tube failures. SYLVANIA’s POWERBALL™ design allows the arc tube to run at a more stable temperature, resulting in improved performance. Users are rewarded with long life and improved lumen maintenance, exceptional color rendering (CRI > 80), improved lamp-to-lamp color consistency, and minimal color shift over life.
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Lamp Color Characteristics
The Phosphor Influence
Fluorescent light is produced by two primary mechanisms: the mercury arc generates narrow bands of energy in the visible and ultraviolet regions, and the fluorescence of the phosphor coating produces a more balanced, continuous spectrum of visible light. The SPD diagram for the Cool White lamp shows a typical fluorescent response, with several distinct spikes rising above the overall curve. The composition of the halophosphor coating on the Deluxe Cool White lamp has been manipulated to improve the color rendering properties. However, these CRI improvements are achieved by sacrificing efficiency.
Further Refinements
When a layer of triphosphors is added to the halophosphor coating — as shown in the DESIGNER® 4100K SPD curve — the spectral energy regions of blue, green and red are enhanced. This enhancement is even more pronounced in the OCTRON® 4100K SPD curve. This technology is one key to the improved color characteristics of modern fluorescent lamps. Further refinements in phosphor and barrier coatings have improved fluorescent efficacy, CRI, lumen maintenance, and service life.
