light
1809, the British chemist David invented the arc lamp, and mankind entered the era of using electric lamps for lighting. 1906, Edison invented the household tungsten light bulb. Since then, incandescent lamps, fluorescent lamps, energy-saving lamps and various high-tech lamps invented by modern high-tech have mushroomed on the lighting stage, greatly facilitating people's production and life.
1863: American Alanson Crane obtained a patent for fire extinguisher. 1879: The theater in California used arc light for the first time. 1923: wilhelm rontgen, the first German scientist to win the Nobel Prize in physics, died. He discovered x-rays at 1895. 1933: new york telegraph company launches singing telegraph for the first time. 1957: styrofoam (styrofoam; I.e. foamed polyester) cooler. 196 1: The Niagara Falls hydroelectric power plant in Canada was put into operation. 1998: For the first time, someone was convicted of hate crimes in cyberspace for sending threatening emails to three Asian college students.
Every year, human inventions are climbing more dazzling peaks. When a huge laboratory called gas factory transports gas through endless underground pipelines, it begins to illuminate the factory (Baldton and Watt introduced gas lamps in 1798, and Phillips and Lee cotton mills in Manchester have been using 1000 gas lamps for a long time since 1805. ), followed by illuminating European cities (London from 1807, Dublin from 18 18, Paris from 18 19, and even remote Sydney from 18 14). ), compared with this achievement, Argandlamp (1782-1884), the first major progress since the invention of oil lamps and candles, has almost no revolutionary role in artificial lighting. At this time, arc lamps began to be known. Professor Wheatstone in London plans to connect Britain and France by submarine telegraph line. In just one year (1845), 48 million passengers took the British railway. Men and women can already run along the 3000-mile-long railway in Great Britain (1846, 1850, more than 6000 miles before). There are 9000 miles of railways in America. Regular steamboat routes have connected Europe with America, Europe and the Indies.
shadowless lamp
Surgical shadowless lamp is used to illuminate the surgical site, so as to best observe small and low-contrast objects with different depths in incision and body control. Because the operator's head, hands and instruments may cause interference shadows at the surgical site, the design of surgical shadowless lamp should eliminate shadows as much as possible and minimize color distortion. In addition, the shadowless lamp must be able to work continuously for a long time without emitting too much heat, because overheating will make the operator uncomfortable and dry the tissue in the operation area.
The surgical shadowless lamp generally consists of one or more lamp holders, which are fixed on the cantilever and can move vertically or circularly. The cantilever is usually connected to the fixed connector and can rotate around it. The shadowless lamp adopts sterilization handle or sterilization hoop (curved rail) for flexible positioning, and has the function of automatic braking and stopping to control its positioning, so as to keep proper space above and around the operation site. The fixing device of the shadowless lamp can be placed on the fixed point of the ceiling or wall, or on the track of the ceiling.
For shadowless lamps installed on the ceiling, a transformer of 1 or above should be installed in the remote control box on the ceiling or wall to convert the input power supply voltage into the low voltage required by most bulbs. Most shadowless lamps have dimming controllers, and some products can also adjust the light field range to reduce the light around the operation site (reflections and flashes from sheets, gauze or instruments will make eyes uncomfortable).
filament lamp
It is generally believed that the inventor of electric light is the great inventor Edison. In fact, the experimental research in this field began long before Edison.
In the patent document of US 1845, Starr of Cincinnati proposed that carbon wires can be used in vacuum bubbles. According to this idea, Swann in Britain used carbonized paper as a filament, trying to make current pass through it and emit light. However, due to the poor vacuum pumping technology at that time, the filament was quickly burned out due to the excess air in the bulb. Therefore, the life of this lamp is quite short, only one hour, and it has no practical value. 1878, the appearance of vacuum pump made Swan carry out the research on incandescent lamps again. 1879 65438+ 10, the incandescent lamp he invented was successfully tested in public and won favorable comments.
1879, Edison also began to study electric lights. He believes that the key to prolong the life of incandescent lamps is to improve the vacuum degree of bulbs and use heat-resistant materials with low power consumption, strong luminescence and low price as filaments. Edison tried 1600 kinds of heat-resistant materials successively, and the results were not satisfactory. 1879 10+265438+. Results The light emitted by carbonized cotton thread was bright and stable, lasting for more than 10 hour. In this way, the carbonized cotton filament incandescent lamp was born, and Edison obtained a patent for it.
Success did not stop Edison. He continues to look for heat-resistant materials that are stronger and more durable than carbon cotton. 1880, Edison developed a carbonized bamboo filament lamp, which greatly prolonged the filament life. In the same year, in 10, Edison set up his own factory in New Jersey and started mass production. This is the earliest commercialized incandescent lamp in the world, and Swann of Britain also set up a factory in Benwell, a suburb of Newcastle, in 18 1.
The invention of incandescent lamp is usually attributed to Edison in America and Swan in England. In Britain, the centenary of the invention of electric light was held in 1978+00, while in America it was held one year later in1/kloc-0.
The competition between the two inventors is fierce, and patent disputes are almost inevitable. Later, the two reached an agreement to jointly establish Edison Swan Electric Company to produce incandescent lamps in Britain. Modern tungsten filament incandescent lamp was successfully trial-produced by American inventor Coolidge in 1908.
Among all the lighting lamps that use electricity, incandescent lamp has the lowest efficiency, and only a small part of the electric energy it consumes, that is, 12%- 18% can be converted into light energy, and the rest is lost in the form of heat energy. As for the lighting time, the service life of this kind of electric lamp usually does not exceed 1000 hours. At this point, halogen lamps are much longer than ordinary incandescent lamps. Halogen lamp is usually a tiny glass tube. Compared with incandescent lamps, halogen lamps are special in that tungsten filaments can "self-regenerate". In fact, the filament and glass shell of this lamp are filled with some halogen elements, such as iodine and bromine. When the filament is heated, tungsten atoms evaporate and move towards the glass tube wall. When they approach the glass tube, the tungsten vapor is "cooled" to about 800℃ and combines with halogen atoms to form tungsten halides (tungsten iodide, tungsten bromide). Tungsten halide moved to the center of the glass tube and landed on the corroded filament. Because tungsten halide is unstable, it will decompose into halogen vapor and tungsten when heated, so that tungsten will be deposited on the filament to make up for the evaporation. This cycle will prolong the service life of the filament. Therefore, the filament of halogen lamp can be made relatively small and the lamp body is very compact. Halogen lamps are generally used in places where spotlight is needed, such as local lighting in writing desks or living rooms.
fluorescence
Structure and function of fluorescent lamp: there are two filaments at both ends of the fluorescent lamp, the tube is filled with trace argon and thin mercury vapor, and the inner wall of the tube is coated with fluorescent powder. When the gas between the two filaments conducts electricity, it emits ultraviolet light, which makes the fluorescent powder emit soft visible light.
The working characteristics of fluorescent lamp: the lamp needs a high voltage at the beginning of ignition, and only a small current is allowed to pass during normal lighting. At this time, the voltage at both ends of the lamp is lower than the power supply voltage.
Filaments are installed at both ends of the fluorescent tube, and the inner wall of the glass tube is coated with a uniform thin phosphor. After the tube is pumped to a vacuum degree of 10-3- 10-4 mm Hg, a small amount of inert gas is filled and a small amount of liquid mercury is injected at the same time. Inductive ballast is an inductive coil with an iron core. The essence of inductance is that when the current in the coil changes, it will cause the change of magnetic flux in the coil, thus generating induced electromotive force in the opposite direction to the current, thus hindering the change of current.
The starter acts as a switch in the circuit, which is composed of neon tube and capacitor in parallel. The capacitor is used to eliminate the electromagnetic interference to the power supply and form an oscillation circuit with the ballast to increase the voltage amplitude of the starting pulse. One electrode in the discharge tube is made of bimetal and heated by neon bubble discharge. When the bimetal is opened and closed, the current of the inductive ballast suddenly changes, resulting in high voltage pulses at both ends of the electron tube.
When the fluorescent lamp is connected to the circuit, glow discharge starts between the two electrodes of the up converter, so that the bimetal expands when heated and contacts with the stationary contact electrode, so that the power supply, ballast, filament and up converter form a closed loop, and the current preheats the filament. After the heating time 1-3 seconds, the glow discharge between the two electrodes of the starter goes out, and then the bimetal cools and disconnects from the stationary contact electrode. When the two electrodes are disconnected, the circuit So ballast generates a high voltage pulse, which is superimposed with the power supply at both ends of the lamp tube to ionize the inert gas in the lamp tube and cause arc discharge. In the normal luminous process, the self-inductance of the ballast also plays a role in stabilizing the current in the circuit.
Energy-saving lamp
Energy-saving lamps, also known as compact fluorescent lamps (CFL lamps for short in foreign countries), were first invented by foreign manufacturers in 1978. Because of its high luminous efficiency (5 times that of ordinary light bulbs), obvious energy-saving effect, long service life (8 times that of ordinary light bulbs), small size, convenient use and other advantages, it has been valued and welcomed by countries and people all over the world. In China, in 1982, the Institute of Electric Light Source of Fudan University first successfully developed SL compact fluorescent lamp. In the past twenty years, the output has increased rapidly and the quality has improved steadily. The country has promoted it as a national key energy-saving product (green lighting product).
The energy-saving products we are talking about now are mainly aimed at incandescent lamps. The light efficiency of an ordinary incandescent lamp is about 0/0 lumen per watt/kloc, and its service life is about 1000 hours. Its working principle is that when the lamp is connected to the circuit, a current flows in the filament, and the thermal effect of the current makes the incandescent lamp emit continuous visible light and infrared light, which can be detected when the filament temperature rises to 700 K. Because the filament temperature is very high when working, most of the energy is wasted in the form of infrared radiation.
Energy-saving lamps mainly heat filaments through ballasts. When the temperature is around 1 160K, the filament begins to emit electrons (because some electron powder is coated on the filament), and the electrons collide with argon atoms to produce inelastic collisions. After argon atoms collide, they gain energy and then collide with mercury atoms. After absorbing energy, mercury atoms undergo jump ionization and emit 253.7nm ultraviolet rays, which excites the phosphor to emit light. Because the temperature of fluorescent lamp filament is about 1 160K, which is much lower than that of incandescent lamp (2200K-2700K), its service life is greatly prolonged, reaching more than 5000 hours. Because it does not have the current thermal effect of incandescent lamp, the energy conversion efficiency of phosphor is also very high, reaching more than 50 lumens per watt.
Besides white light (cold light), there are yellow light (warm light) energy-saving lamps. Generally speaking, under the same wattage, energy-saving lamps save 80% more energy than incandescent lamps, prolong their average life by 8 times, and radiate only 20%. Under non-strict conditions, a 5-watt energy-saving lamp can be regarded as a 25-watt incandescent lamp, a 40-watt 7-watt energy-saving lamp and a 60-watt 9-watt energy-saving lamp.