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The incandescent light bulb, or lamp, makes light by heating a metal filament wire to a high temperature until it glows. The hot filament is protected from air by a glass bulb that is filled with inert gas or evacuated. The light bulb is supplied with electrical current by feed-through terminals or wires embedded in the glass. Most lamps are used in a socket.
Incandescent bulbs are produced in a wide range of sizes, light output, and voltage ratings, from 1.5 volts to about 300 volts. They require no external regulating equipment and have a low manufacturing cost, and work equally well on either alternating current or direct current. As a result the incandescent lamp is widely used in household and commercial lighting, for portable lighting such as table lamps, car headlamps, and flashlights, and for decorative and advertising lighting.
A halogen lamp, also known as a tungsten halogen, quartz-halogen or quartz iodine lamp, is an incandescent lamp that has a small amount of a halogen such as iodine or bromine added. The combination of the halogen gas and the tungsten filament produces a halogen cycle chemical reaction which redeposits evaporated tungsten back onto the filament, increasing its life and maintaining the clarity of the envelope. Because of this, a halogen lamp can be operated at a higher temperature than a standard gas-filled lamp of similar power and operating life, producing light of a higher luminous efficacy and color temperature. The small size of halogen lamps permits their use in compact optical systems for projectors and illumination.
An LED lamp (LED light bulb) is a solid-state lamp that uses light-emitting diodes (LEDs) as the source of light. The LEDs involved may be conventional semiconductor light-emitting diodes, organic LEDs (OLED), or polymer light-emitting diodes (PLED) devices. However, PLED technologies are not commercially available. Diode technology improves steadily.
LED lamps can be made interchangeable with other types of lamps. Assemblies of high power light-emitting diodes can be used to replace incandescent or fluorescent lamps. Some LED lamps are made with identical bases so that they are directly interchangeable with incandescent bulbs. Since the luminous efficacy (amount of visible light produced per unit of electrical power input) varies widely between LED and incandescent lamps, lamps are usefully marked with their lumen output to allow comparison with other types of lamps. LED lamps are sometimes marked to show the watt rating of an incandescent lamp with approximately the same lumen output, for consumer reference in purchasing a lamp that will provide a similar level of illumination.
Efficiency of these devices continues to improve with some chips able to emit > 100 lumens per watt. LEDs do not emit light in all directions, and their directional characteristics affect the design of lamps. The efficiency of conversion from electric power to light is generally higher than with incandescent lamps. Since the light output of many types of light-emitting diodes is small compared to incandescent and compact fluorescent lamps, in most applications multiple diodes are assembled.
LED lamps offer long service life and high energy efficiency, but initial costs are higher than those of fluorescent and incandescent lamps. Life cycle of LED lamps is multiple compared to incandescent lamps, however, since the degradation of LED chips reduces luminous flux over life cycle as with conventional lamps.
An OLED light source is a thin, flexible sheet of material consisting of three layers, a polymer or sublimed molecular film sandwiched between two layers of electrodes, one of them transparent. Current passes through the material until it emits light through its transparent layer. OLEDs are similar to electroluminescent lighting, in which a sheet of material is excited so that it emits light.
A multifaceted reflector (MR) light bulb is a format for halogen bulbs, made by a variety of manufacturers. MR lamps were originally designed for use in slide projectors, but are now used in applications including residential lighting and retail lighting. They are suited to a variety of applications that require directional lighting, such as track lighting, recessed ceiling lights, desk lamps, pendant fixtures, landscape lighting, retail display lighting and bicycle headlights. Lamps are designated by symbols such as "MR 16" where the diameter is represented by numerals. Common sizes for general lighting are MR 16 and MR 11, with MR 20 and MR 8 used in specialty applications.
Halogen MR16 lamps consist of a halogen capsule (bulb) integrated with a pressed glass reflector. The reflector of an MR16 lamp is 2 inches (51 mm) in diameter. The base conforms to bi-pin GU5.3 standard. The compact size of the MR16 allows for much smaller, more discreet fixtures than the incandescent reflector bulbs that pre-dated MR16s.
The reflector controls the direction and spread of light cast from the lamp. MR16 lamps are available with different beam angles from narrow spot lights of as small as 7° to wide flood lamps of 60°.
"MR" refers to the multifaceted reflector which has multiple small facets. This reflector gives a soft edge to the area illuminated by the lamp. MR16 lamps are also available with smooth reflectors, resulting in a sharper fall-off to the illuminated area.
A fluorescent lamp or a 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 bulb to glow. A fluorescent lamp converts electrical energy into useful light much more efficiently than incandescent lamps. The luminous efficacy of a fluorescent light bulb can exceed 100 lumens per watt, several times the efficacy of an incandescent bulb with comparable light output.
High-pressure sodium lamps use sodium under high pressure as the primary light-producing element. HPS lamps are among the most efficacious light sources, with efficacies as high as 150 lumens per watt.
An electric lamp that produces light directly from an arc discharge under high pressure. Metal halide, high-pressure sodium, and mercury vapor are types of HID lamps.
A ballast is a device required by electric-discharge light sources such as fluorescent or HID lamps to regulate voltage and current supplied to the lamp during start and throughout operation. The ballast factor depends on both the ballast and the lamp type; a single ballast can have several ballast factors depending on lamp type. The BEF, or ballast efficiency factor, is the ratio of the ballast factor to the active power (in watts), usually expressed as a percent. It is used as a relative measurement of the system efficacy of the fluorescent lamp/ballast combination.
Occupant Sensors respond to the presence and absence of people in the sensor's field of view. When the motion detector senses movement, it sends the appropriate signal to the control unit, which then processes the input signal to either close or open the relay that controls power to the lights. The basic technology behind the occupant sensor derived from security systems developed for residential and commercial applications to detect intruders. However, the motion sensor has been refined so that it responds not only to the presence of occupants, but also to the absence of occupants in the space.
A lighting control system consists of a device that controls electric lighting and devices, alone or as part of a daylight harvesting system, for a public, commercial, or residential building or property, or the theater. Lighting control systems are used for working, aesthetic, and security illumination for interior, exterior, and landscape lighting, and theater stage lighting productions. They are often part of sustainable architecture and lighting design for integrated green building energy conservation programs.
Lighting control systems, with an embedded processor or industrial computer device, usually include one or more portable or mounted keypad or touchscreen console interfaces, and can include mobile phone operation. These control interfaces allow users the ability to remotely toggle (on-off) power to individual or groups of lights (and ceiling fans and other devices), operate dimmers, and pre-program space lighting levels.
A major advantage of a lighting control system over conventional individual switching is the ability to control any light, group of lights, or all lights in a building from a single user interface device. Any light or device can be controlled from any location. This ability to control multiple light sources from a user device allows complex "light scenes" to be created. A room may have multiple scenes available, each one created for different activities in the room. A lighting scene can create dramatic changes in atmosphere, for a residence or the stage, by a simple button press. In landscape design landscape lighting, fountain pumps, water spa heating, swimming pool cover, motorized gate, and outdoor fireplace ignition can all be remotely or automatically controlled.