Incandescent light bulbs, also known as light bulbs, work on the principle that current flows through filaments (tungsten, with a melting point of more than 3,000 degrees Celsius) to generate heat, and spiral filaments continuously collect heat, making the temperature of filaments above 2000 degrees Celsius, and filaments in incandescent light. In the state, it glows like a red-hot iron glows. The higher the temperature of the filament, the brighter the light emitted. It is called an incandescent lamp. When the incandescent lamp emits light, a large amount of electric energy will be converted into heat energy, and only a very small part (perhaps less than 1%, not counted) can be converted into useful light energy.
The light emitted by an incandescent lamp is full-color light, but the proportion of various color light components is determined by the luminescent substance (tungsten) and the temperature.
The life of an incandescent lamp is related to the temperature of the filament, because the higher the temperature, the easier it is for the filament to sublimate. When the tungsten wire is sublimated to a relatively thin state, it is easily burned after being energized, thereby ending the life of the lamp. Therefore, the greater the power of the incandescent lamp, the shorter the life.
Incandescent lamps have the lowest efficiency among all electrical lighting fixtures. Only a small part of the electrical energy it consumes can be converted into light energy, and the rest is lost in the form of heat energy. As for the lighting time, the life time of such lights usually does not exceed 1000 hours.
Fluorescent lamp is also called fluorescent lamp. Its working principle: fluorescent tube is simply a closed gas discharge tube. The main gas in the tube is an argon gas (also containing 氖neon or 氪krypton) gas pressure of about 0.3% of the atmosphere. It also contains a few drops of mercury - a trace of mercury vapor. Mercury atoms account for about one-thousandth of all gas atoms.
Fluorescent tubes are the mercury atoms that rely on the lamp tube. Ultraviolet light is emitted by the process of gas discharge (the main wavelength is 2537 Angstroms = 2537 x 10-10 m). About 60% of the electrical energy consumed can be converted to ultraviolet light. Other energy is converted into heat energy.
The fluorescent lamp absorbs ultraviolet light from the fluorescent material on the inner surface of the lamp tube to release visible light. Different fluorescent substances emit different visible light. The efficiency of converting ultraviolet light to visible light is about 40%. Therefore, the efficiency of fluorescent lamps is approximately 60% x 40% = 24% - approximately twice that of the same power tungsten lamp.
The disadvantages of fluorescent lamps are pollution to the environment after the production process and scrapping, mainly mercury pollution, not environmental protection. With the improvement of the process, the use of amalgam to reduce mercury pollution gradually.
Energy-saving lamps, also known as compact fluorescent lamps (abbreviated as CFL lamps abroad), have high luminous efficacy (5 times that of ordinary light bulbs), significant energy saving effects, long life (8 times that of ordinary light bulbs), small size, and ease of use. Its working principle and fluorescent lamps are basically the same.
In addition to white light (cold light), energy-saving lamps now have yellow (warm light). Generally speaking, under the same wattage, an energy-saving lamp can save 80% energy compared with incandescent lamps, extend the average life expectancy by 8 times, and heat radiation is only 20%. Under non-strict conditions, a five-watt energy saving light can be regarded as an incandescent lamp equal to 25 watts. A seven-watt energy-saving light equates to about 40 watts, and a nine watts equates to about 60 watts.
The electromagnetic radiation of energy-saving lamps also comes from the ionization reaction of electrons and mercury gas. At the same time, energy-saving lamps need to add rare earth phosphors. Since rare earth phosphors are radioactive, energy-saving lamps also produce ionizing radiation (ie, radiation nuclear radiation). The indeterminacy of electromagnetic radiation on the human body, and the harmful effects of excessive radiation on nuclear radiation are more worthy of attention. In addition, due to the limitation of the working principle of energy-saving lamps, mercury in the lamp will inevitably become a major source of pollution. An ordinary energy-saving lamp has a mercury content of about 5 milligrams, which is only enough to stain a ballpoint pen tip, but it may cause 1,800 tons of water contamination after seeping into the ground.
LED (Light Emitting Diode), a light emitting diode, is a solid-state semiconductor device capable of converting electrical energy into visible light, which can directly convert electricity into light. The heart of the LED is a semiconductor wafer.
One end of the wafer is attached to a support, one end is a negative electrode, and the other end is connected to the positive electrode of the power supply, so that the entire wafer is encapsulated with epoxy resin. The semiconductor wafer consists of two parts, one is a P-type semiconductor, in which holes are dominant, and the other end is an N-type semiconductor, which is mainly electrons. When the two semiconductors are connected, a P-N junction is formed between them. When the current is applied to the wafer through the wire, the electrons are pushed to the P area. In the P area, the electrons recombine with the holes, and then they emit energy in the form of photons. This is the principle of LED light emission. The wavelength of light, which is the color of light, is determined by the material that forms the P-N junction.
Initially, LED was used as the indicator light source for instrumentation. Later, various light-colored LEDs were widely used in traffic signals and large-area displays, resulting in good economic and social benefits. Take the 12-inch red traffic signal as an example. In the United States, a long-life, low-efficiency, 140-watt incandescent lamp was used as the light source, which produced 2,000 lumens of white light. After passing through the red filter, the light loss was 90%, leaving only 200 lumens of red light. In the newly designed lamp, Lumileds uses 18 red LED light sources, including the circuit loss, a total of 14 watts of power, can produce the same luminous efficiency. Automotive signal lights are also an important area for the application of LED light sources.
For general lighting, people need a white light source. In 1998, the white LED development was successful. The LED is made by encapsulating GaN chips and yttrium aluminum garnet (YAG) together. The GaN wafer emits blue light (λp=465 nm, Wd=30 nm). The Ce3+-containing YAG phosphor produced by high-temperature sintering is excited by this blue light to emit yellow light with a peak at 550 nm. The blue LED substrate is mounted in a bowl-shaped reflective cavity covered with a thin layer of resin mixed with YAG, approximately 200-500 nm. The part of blue light emitted by the LED substrate is absorbed by the phosphor, and the other part of the blue light is mixed with the yellow light emitted by the phosphor to obtain white light. Now, for InGaN/YAG white LEDs, by changing the chemical composition of the YAG phosphor and adjusting the thickness of the phosphor layer, white light of a color temperature of 3500-10000K can be obtained. This method of obtaining white light through a blue LED is simple in construction, low in cost, and high in technology maturity, and therefore it is used most.
LED lamps are relatively expensive compared to other lighting fixtures. In addition, the current LED industry lacks uniform standards, the quality of products produced by various companies is different, there are still many uncertainties in various aspects such as light efficiency, color rendering and longevity, but LED technology is also continuously improving, I believe that one day a certain LED technology Will become more mature, into the homes of ordinary people.
Dalian Xinghai Technology Co., Ltd.