Also, the quartz capsules of the lamps may rupture or explode upon failure of the lamps. MR lamps, like all quartz-halogen lamps, produce some undesirable ultraviolet light. Using an electronic transformer with a soft start feature can considerably extend life, as it reduces the characteristically high inrush current that occurs initially when the lamp is cold. With both types of incandescent bulbs, useful life can be considerably shortened if their filaments experience mechanical shock or vibration. Halogen lamps (18 lm/W typical) are more energy efficient than regular incandescent lamps (15 lm/W typical) but still fall far behind other more-recent types such as fluorescent lamps (80–100 lm/W), gas discharge lamps (100–200 lm/W depending on types), and LEDs (125–150 lm/W typical in bright white depending on style). However, dichroic lamps must only be used in compatible fixtures that can dissipate the heat. This type reduces heating of illuminated objects since less infrared radiation is present in the light beam. Others use selective dichroic coating that reflects visible light and allows infrared radiation to pass through. Some lamps use an aluminum coating as a reflector. MR lamps are available with different beam angles from narrow spot lights of as small as 7° to wide flood lamps of 60°. The reflector controls the direction and spread of light cast from the lamp. The compact size of the MR base allows for much smaller, more discreet fixtures than the incandescent reflector bulbs that pre-dated MRs. Most MR lamps consist of a halogen capsule (or, bulb) integrated with a pressed glass reflector with a base conforming to bi-pin GU5.3 standard. Note that this lamp was not "multifaceted" faceted reflectors were introduced in 1971.Ĭharacteristics Design and construction This allowed more flexible electrical mounting arrangements and more precise focussing. The innovation was using the lamp rim, rather than the base, as the reference plane for focusing. Wiley of General Electric (USA) was awarded patent #3,314,331 for a miniature reflector lamp in 1967. Many run on low voltage rather than mains voltage alternating current so require a power supply. Common sizes for general lighting are MR16 ( 16⁄ 8 inches, 51 mm) and MR11 ( 11⁄ 8 inches, 35 mm), with MR20 ( 20⁄ 8 inches, 64 mm) and MR8 ( 8⁄ 8 inch, 25 mm) used in specialty applications. MR lamps are designated by symbols such as MR16 where the diameter is represented by numerals indicating units of eighths of an inch. They are suited to applications that require directional lighting such as track lighting, recessed ceiling lights, desk lamps, pendant fixtures, landscape lighting, retail display lighting, and bicycle headlights. MR lamps were originally designed for use in slide projectors, but see use in residential lighting and retail lighting as well. Line drawing of an LED MR16 lamp, with a heatsink rather than a reflectorĪ multifaceted reflector (often abbreviated MR) light bulb is a reflector housing format for halogen as well as some LED and fluorescent lamps.
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