In general, a fluorescent lamp includes a light-tranmissive discharge tube coated with a fluorescent layer, electrodes for discharging in the discharge tube, and a discharge gas sealed in the discharge tube. The base layer, typically made of alumina or halophosphor, is applied between the phosphor layer and a glass tube. There are two principal types of phosphors used in fluorescent lamps: relatively inexpensive halophosphors and relatively expensive rare earth phosphors. Halophosphors exhibit poorer color rendering properties and lower lumens compared with more expensive rare earth phosphors. Rare earth phosphors exhibit excellent color rendering properties and relatively high lumens. Glass used in the fluorescent lamp can be roughly divided into two parts, i.e., a cylindrical bulb part and a stem part. The bulb part is normally in the form of a straight tube or a circular tube obtained by heat-forming the straight tube. In recent years, for the purpose of enhancing the lamp efficiency or downsizing the lamp, fluorescent lamps having a complicated shape such as a U tube and a twin tube having two U tubes connected to each other have been developed. Soda-lime glass is the most common type of glass for the discharge tubes of fluorescent lamps. Soda-lime glass is preferred because the sodium atoms (or ions) in the glass help prevent unconverted UV from escaping through the glass envelope. Fluorescent lighting tubes are produced to maximise the light that is emitted from them and hence having openings within the fluorescent material coating is generally not desirable. The discharge tube defines the boundary including at least one straight portion and the ends of the tube are re-entrant into the zone. A lamp support housing, which is disposed within the zone, receives the ends of the tube and provides electrical connection to the electrodes. The electrodes are coated with an emission mixture, typically comprising carbonates of barium, calcium, and strontium. The carbonates are converted to a ceramic material comprising the corresponding oxides when activated. Mercury is the primary component for the (efficient) generation of ultraviolet (UV) light in mercury vapor discharge lamps.

Fluorescent lamps are low-pressure gas discharge lamps. The generation of light in gas discharge lamps is based on a process wherein charge carriers, electrons or ions, are accelerated so strongly by an electric field between the electrodes of the lamps that collisions with the gas atoms or molecules in the filling gas of the lamps cause these gas atoms or molecules to be excited or ionized. When the atoms return to the ground state, and also in the case of the recombination of electrons and ions, a more or less substantial part of the potential energy is converted to radiation. The light of the fluorescent lamp is emitted as a result of the excitation of atoms those of the mercury vapor and the fluorescent coating). To start a fluorescent lamp, electron emission from the electrodes may be induced. When electric power is applied to the electrodes, the sealed discharge gas generates discharge and plasma is generated in the discharge tube. Then, electrons in the plasma excite fluorescent materials on the inner surface of the discharge tube to make them emit the visible-light. The electrons ejected from the cathode filaments collide with the mercury atoms of the vapor and cause the mercury atoms to emit radiation which consists for the most part of ultraviolet rays, which are invisible. The ultraviolet light strikes the fluorescent substance with which the wall of the tube is coated and, depending upon the coating, may cause the substance to emit radiation with a longer wavelength in the visible rage of the spectrum. Standard fluorescent tubes which are used in the lighting of commercial or domestic premises consist of a tube where the fluorescent material coating is applied substantially over the entire length of the tube. The fluorescent material chosen normally emits a white or off white colour so that such a tube can efficiently illuminate a room. By a suitable choice of the phosphors, it becomes possible to give the light of the fluorescent lamp any desired color. The visible color depends upon the intensity ratio in the wavelength spectrum of the radiation generated; the brightness is determined by the overall intensity. The electron source is generally a metal coil, usually tungsten, containing an electron emissive material. Two such coils are provided, one at either end of an elongated glass tube. The fluorescent light is typically continuously operated in a steady state mode with a constant level of light output. A fluorescent lamp cannot be turned on and off like a conventional light bulb.

The light output of fluorescent lamps is critically dependent upon mercury vapor pressure (vapor density) within the lamp envelope. The luminous efficacy of a fluorescent lamp changes according to the mercury-vapor pressure ratio of the lamp. All fluorescent lamps contain mercury which is vaporized during lamp operation. The mercury vapor atoms efficiently convert electrical energy to ultraviolet radiation with a wavelength of 253.7 nm when the mercury vapor pressure is in the proper range. The mercury-vapor pressure is controlled by the temperature of a cold spot, which is the coldest portion of the fluorescent lamp during the lamp operation. Fluorescent lamps typically include at least one tubulation that has an opening into the interior of the lamp envelope and which, in construction of the lamp, is used as an exhaust tubulation. At completion of manufacture, the exhaust tubulation is hermetically tipped off and the tipped end typically becomes the lamp cold spot. The mercury vapor pressure may be maintained within the desired range either by controlling the cold spot temperature of the lamp or by introducing other metallic elements into the lamp in the form of amalgams that maintain the mercury vapor pressure. The pressure of the mercury vapor depends on the temperature of the cold spot in the tube which is a place where mercury condenses. Since the electrodes of fluorescent lamps generate heat, the cold spot temperature is influenced by the relative position of the electrodes with respect to the cold spot. When the temperature of the cold spot becomes high, more mercury evaporates, so that the luminous flux of the fluorescent lamp can increase. If the temperature of the cold spot becomes too high, then the luminous flux decreases, because, the in excess evaporated mercury absorbs ultraviolet rays generated in the fluorescent lamp, which are changed to visible light. Amalgams reduce the mercury vapor pressure relative to that of pure mercury at any given temperature and thereby permit optimum light output at elevated temperatures. Amalgams also provide a broadened peak in the light output versus temperature curve, so that near optimum light output is obtained over an extended range of ambient temperatures. The amalgam is commonly located in the exhaust tubulation cold spot. So long as the mercury vapor within the lamp remains at the desired pressure, the lamp will continue to operate normally, producing maximum lumens.

A typical fluorescent lamp generates light by energizing a pair of spaced-apart electrodes positioned within a phosphor-coated sealed tube of a vapor containing mercury. When the electrodes are energized, a flow of electric current passes through the inert gas. During the discharge, the inert gas emits several wavelengths of light including ultraviolet light. The ultraviolet light strikes and excites the fluorescent material coating within the tube. In general, there are two types of electrodes used in fluorescent bulbs: hot-cathode electrodes and cold-cathode electrodes. Hot-cathode electrodes include a resistive filament, which like a filament in an incandescent bulb, is heated by current passing through it. This heat facilitates operation of the lamp. However, these hot-cathode filaments are fragile and require particularly complex electrical circuitry to operate effectively in this scanning environment. Fluorescent lamps, both cold cathode and hot cathode, operate with a coating of emissive material on the cathodes which readily release electrons for the proper functioning of the lamp. The amount of power and heat dissipated at the cathodes to achieve this emission is relatively low during normal operation. Electrodeless fluorescent lamps have recently been introduced into the market for indoor, outdoor, industrial and commercial applications. Electrodeless fluorescent lamps typically utilize an inductively coupled plasma. The plasma that generates UV and visible light is produced in a glass (or quartz) envelope filled with inert gas such as argon, krypton or the like and metal vapor such as mercury, sodium or the like. The induction coil that generates the inductively coupled plasma is positioned in the close proximity of the lamp envelope. A feature of electrodeless fluorescent lamps is that they have a longer life than fluorescent lamps with electrodes, owing to the absence of electrode. Because they lack electrodes, electrodeless fluorescent lamps have a longer lamp life than fluorescent lamps with electrodes, which are the major factor that determines the lamp life in conventional fluorescent lamps with electrodes, and as a result they are expected to become even more widespread in the future. The life of electrodeless fluorescent lamps is substantially higher than that of conventional fluorescent lamps and can reach 100,000 hours.

The compact fluorescent lamp (CFL) is now the most popularly used lamp used in commercial and domestic lightings. A compact self-ballasted fluorescent lamp consists of an arc tube fixed to a holder, a driving apparatus for driving the arc tube, and a case provided so as to keep the driving apparatus from such as human hands at the time of driving. In order to keep it compact, a plurality of constituent tubes that each has a U-shaped discharge path is connected together, so as to form a tube with one meandering discharge path. The discharge paths of the constituent tubes are connected by one or more bridges, in such a way that an area in the vicinity of an end of a constituent tube is connected to an area in the vicinity of an end of another constituent tube, wherein each of these ends connected is one of the ends that are positioned opposite to the turning portion of each constituent tube. The constituent tubes connected in such a manner are disposed on a case so that the bridged portions are positioned close to the lamp base, and the turning portions are away from the lamp base. At one end of the case, a base is fixed for fixing the compact self-ballasted fluorescent lamp to a socket, and for taking in power from the commercial electric source. At both ends of the discharge path of the arc tube, electrodes made of filament coil are provided, and each lead therefrom is connected to the driving apparatus. When enough electric voltage is applied to the first and second electrodes, the second electrode emits electrons and causes the mercury to discharge, thereby conducting the electric current to the first electrode. In the course of discharge, the mercury emits ultra violet rays which excite the phosphor coating to generate visible light. The second electrode is usually shaped as a wire in a dimension of millimeter. Compact single-capped fluorescent lamps are becoming prevalent for their high lamp efficiency as a light source of a lamp apparatus provided at commercial facilities and offices in a buried condition in a ceiling.

A fluorescent lamp is broadly divided into a hot-cathode type and a cold-cathode type by constituent of the electrodes. A cold electrode fluorescent lamp (CCFL) has a basic structure similar to CFL. In the cold cathode fluorescent lamp (CCFL), the electrodes consist of materials that radiate many electrons due to high voltages applied. A cold cathode fluorescent flat lamp is a plasma light-emitting device where a high voltage waveform is applied between electrodes to excite the inert gas in the discharge space to high-energy excited molecules, ions, and electrons. Those high-energy excited molecules, ions, and electrons are so-called plasma. The plasma will emit the ultraviolet rays to release the energy and to further excite the fluorescent materials in the cold cathode fluorescent flat lamp, thereby emitting the visible light. The cold cathode fluorescent lamp requires a high starting voltage (about 1500 volts) for a short period of time, in order to ionize the gas contained within the lamp tube and thereby ignite the lamp. After the gas is ionized and the lamp is ignited, less voltage is needed to keep the lamp on. CCFL tubes typically contain a gas, such as Argon, Xenon, or the like, along with a small amount of mercury. A power conversion circuit is used for driving the CCFL. The power conversion circuit accepts a direct current (DC) supply voltage and provides a substantially sinusoidal output voltage to the CCFL. The brightness of the CCFL is controlled by controlling the current through the CCFL. Cold cathode fluorescent lamps (CCFL) have been widely used in a variety of fields such as liquid crystal displays, scanners, automobile instrument boards, small sized advertising neon signs and picture frame displays because of high luminous intensity, uniform luminous emittance, small-diameter tube and being made in various shapes. Because the cold electrode functions at a lower temperature, the life span of CCFL usually lasts longer than its comparative models of CFL.

The typical fluorescent lamp requires a ballast to provide current to the electrodes. A ballast contains devices such as reactance, suitable transformers, capacitors, and other required starting and operating components. The ballast provides a high striking voltage required to initiate an arc across the lamp tube and regulates the current flowing through the arc after it has been struck. A traditional ballast is a special transformer that uses electromagnetic principles to generate operating and starting voltages for fluorescent lamps. An electronic ballast uses electronics to achieve the same result. In a self-ballasted fluorescent lamp, the lamp and a ballast circuit therefor are integrally formed. The starting device or starter, a critical component for ignition of fluorescent tubes, operates in conjunction with the ballast to produce high inverted potential necessary for turning on a fluorescent tube, which is the operating theory behind the conventional fluorescent lamps. A fluorescent lamp starter circuit is essentially a time delay switch that allows a preheating circuit to warm the filaments at each end of a fluorescent lamp before the lamp is ignited. Most electronic starters now found on the market are based on the half-wave rectification model, such that the fluorescent tube often has to be ignited many times before it is successfully actuated.