Electronics Information Home
Electronics Information
Outdoor lighting
| Outdoor lighting |
| Saturday, 12 August 2006 | |
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Outdoor lighting systems generally include a plurality of lighting units spaced along the road or highway, each of which includes an electric light that is supported on the distal end of a tubular mast whose proximal end is anchored into the ground. In some assemblies, the lights are suspended over the street or highway by a cantilevered support member attached to the mast. In other instances, a ring of high intensity lights circumscribes the distal end of the mast. The lighting fixtures generally include a housing, a reflector assembly having a halogen or conventional bulb, and a lens or window. Many configurations of outdoor lighting systems are developed to provide a different lighting effect. Various types of outdoor lighting fixtures typically serve both utilitarian and decorative purposes in that they aid in lighting outdoor lawns, decks, patios, parking lots, driveways, and other areas, as well as being of an attractive design to complement such areas. Such lighting fixtures typically employ a light source, various types of electrical circuitry to effect intermittent illumination and/or some form of mechanical drive to effect movement of one or more objects relative to the light source to create the desired effects. Outdoor street lighting fixtures customarily have a light lens which covers the light-producing means emitting light from the luminaries. Outdoor lighting systems provide projection of light from a source in various directions and at various intensities. Landscape and outdoor lighting systems generally include one or more lighting fixtures which are connected to either a 12 V transformer or a standard 120 VAC line. Some outdoor lighting systems utilize individual lighting fixtures having solar cells and rechargeable batteries. Most electric lighting fixture housings and fittings have been made of metal. Becasue metal fixtures are strong and do not deteriorate or deform as the result of the high temperatures generated within the fixture by incandescent 110-volt lamps used in conventional lighting fixtures. Conventional outdoor post lighting fixtures are permanently secured to the ground. Many outdoor ground lighting systems are timer controlled (mechanical or electronic timer) to be on for variously adjustable selected periods of time during hours of darkness. Outdoor lighting control circuits have widespread uses to control lamps for illuminating streets, parks, and parking lots. Many outdoor luminaries, particularly street lights, are automatically turned on and off by a light sensitive device responsive to the level of natural light in the immediate area. At night when it gets dark, the lights automatically come on and stay on until morning when they are automatically turned off. Conventional outdoor lighting controllers are generally composed of a light sensing element such as fabricated from cadmium sulfide for sensing variation of daylight level and a bimetallic thermal switch in the power supplying circuit for the light being controlled. Typically, outdoor lighting control circuits include a photosensitive element that responds to the presence or absence of ambient light. The photosensor detects outdoor ambient light and for converting the detected light into an analog electrical signal. A level detector converts the analog signal into a digital signal having high and low states corresponding to daylight and nighttime conditions. At night the photosensitive element limits the current to the relay which closes the relay contacts. Thus the lamp is connected with its power source and turns the light on. During daylight, the photosensitive elements allow higher alternating current to open the contacts. This connects the circuit from the alternating current lines to the lamp and turns the light off in daylight. |

