Lamps & lighting systems

Light is a form of electromagnetic energy. Electromagnetic energy is divided into different spectrums based on the wavelength of the electromagnetic energy. Visible light is one of these spectrums. A number of different principles of electrical lighting have been developed over the years. Incandescent lighting was the first lighting principle to receive widespread use, and is still the most widely used lighting principle used to date. An incandescent lamp produces illumination by heating of an internal filament to generate radiant light. The Edison type incandescent lamps and tungsten-halogen incandescent lamps are still the primary light sources in residential and commercial lighting fixtures. These lamps generally include incandescent filaments within a predetermined and non-oxidizing atmosphere which contained in a glass envelope. A major disadvantage of incandescent lighting is that the filaments are very fragile and short-lived and require periodic replacement to maintain the lights in working order. A fluorescent lamp is a low-pressure gas discharge source. The fluorescent lamp uses phosphorus material to produce light when a gas is activated to energize the phosphorus material. Fluorescent interior lighting is in widespread use due to the relatively high efficiency of fluorescent lamps and an emission light spectrum which more closely approximates daylight as compared to incandescent lighting. The typical fluorescent lamp is composed of a glass tube containing an inert gas and a small amount of mercury. Phosphor coats the inside of the glass tube, and each end of the glass tube includes an electrode. In operation, a ballast provides current to the electrodes. Fluorescent lamps are used in a number of applications where light is required but the power required to generate light is limited. One particular type of fluorescent lamp is a cold cathode fluorescent lamp (CCFL). Cold-cathode fluorescent lamps are desirable since they are more efficient and offer savings in both energy consumption and operating expenses. To illuminate a target a substantial distance away from the source of light, a high-intensity lamp capable of emitting a high-radiant beam is generally employed. A halogen lamp is generally well known one of high-intensity lamps, but a high intensity discharge (HID) lamp is now developed over the world. As compared with the halogen lamp, the HID lamp is effective to provide a high illumination and also to accomplish an energy saving. High intensity discharge (HID) lamps have been in use for a number of years in a variety of lighting applications. HID lamps enjoy a number of advantages over incandescent lighting and fluorescent lighting, but also have some comparative limitations. For example, HID lamps typically do not start immediately, but require some warm up time to come to full illumination. Four types of HID lamps are commonly used, including mercury vapor, low pressure sodium, high pressure sodium and metal halide. Metal halide arc discharge lamps are frequently employed in commercial usage because of their high luminous efficacy and long life. A typical metal halide arc discharge lamp includes a quartz or fused silica arc tube that is hermetically sealed within a borosilicate glass outer envelope. Other principles of lighting have been developed more recently. Among these is the LED (light emitting diode). LEDs have many advantages over traditional lighting sources such as incandescent bulbs as they are cheaper to produce, more robust, and require less power. LEDs are especially desirable as they emit light with high power efficiency over specific colors in the spectrum. LEDs are available in a number of different colors, and the lighting intensity may be varied by means of a simple variable resistor or rheostat. The use of light fixtures has become a popular choice to effectively deter unwanted activity and increase security for either commercial or private property. Lighting fixtures are employed in a variety of applications for illuminating, marking, designating and signaling areas, structures and objects. Incandescent bulbs, quartz bulbs, fluorescent bulbs, LED lamps, and mercury lamps are most frequently used on daily lighting fixtures as light sources. There are a variety of lighting fixtures which may be used to provide illumination in rooms. Regular lighting fixtures for home use include ceiling fixtures, pendants, swag lamps, floor lamps, desk lamps, wall lamps, lamp socket and plug assemblies. One type of lighting fixture is recessed into a space above the ceiling of a room. A typical recessed lighting fixture includes a frame, a reflector, a junction box and structure for attaching the frame to the ceiling. In general, lighting fixtures that emit light such as an incandescent light or a fluorescent lamp are attached to given locations (in particular, ceiling) in an office, homes, buildings, and the like, in order to make light surrounding environments when it gets dark.