If the basic lighting conditions such as illuminance, color temperature, lighting height, and amplitude are all the same, what is the basis for choosing the lamp light source? Incandescent lamp, halogen lamp, fluorescent lamp, energy-saving lamp, LED lamp, which one is best for children's eyes?
1. Incandescent lamp
Incandescent lamp (incandescent lamp) is an electric light source that heats the filament to an incandescent state and emits visible light using thermal radiation.
The kind of bulbs that we used when we were young would be very hot for a long time. We often hula and burned the filament, which is the incandescent bulb.
There is a well-known story: Edison failed to experiment 999 times in order to invent the light bulb. People laughed at him. He said that I knew at least 999 ways would not work.
If Edison heard this story, he might respond this way: I have not said this.
Because-long before Edison, British electrical engineer Swan (j. Swan) began to study electric lamps in the late 1840s. After nearly 30 years of hard work, Swan finally found a carbon filament suitable for filament. On December 18, 1878, Swan trial-produced the first incandescent electric bulb.
In 1879, Edison also began to invest in the research of electric lamps. He believed that the key to extending the life of incandescent lamps is to increase the vacuum of the bulb and use a heat-resistant material with low power consumption, strong light emission, and cheap prices. Edison has tried 1600 A variety of heat-resistant materials, the results are not ideal. On the evening of October 21, 1879, Edison made incandescent lamps made of carbon fiber (that is, carbon filament), which was the first to send electric light sources into the home. Edison used carbonized cotton thread as the filament, put it into the glass ball, and then started the air machine to evacuate the ball into a vacuum. As a result, the light emitted by the carbonized cotton filament is bright and stable, which is bright for more than 10 hours (45 hours). In this way, the carbonized cotton filament incandescent lamp was born, and Edison obtained a patent for this.
Since then, Edison has also been committed to the improvement of incandescent lamps and large-scale commercial use. Later inventors continued to improve the materials and processes of incandescent lamps. The entire history of the development of incandescent lamps is the history of improving the luminous efficiency of the bulb.
However, in more than a hundred years, this effort has not achieved the desired effect. The incandescent lamp has never been able to solve its original defects: less than 10% of the electrical energy it consumes can be converted into light energy (ordinary incandescent lamps Only 2%), and the rest is lost in the form of heat. At the same time, the higher the temperature of the filament, the faster the tungsten filament evaporates, making the life of most incandescent lamps shorter.
Therefore, although incandescent lamps have many advantages-the color of the light is closest to the color of the sun, the color rendering is good, the spectrum is uniform and not abrupt-but the waste of energy is huge. Since the beginning of 2007, the Australian government first announced the complete elimination of incandescent lamps in the form of legislation At the beginning, more than a dozen countries and regions have successively released incandescent lamp phase-out plans. my country has also gradually implemented a phase-out plan since 2011. By October 1, 2016, it is prohibited to sell and import incandescent lamps for general lighting of 15 watts and above.
Summary: If you want to use an incandescent lamp as a light source for a lamp, there will indeed be difficulties in purchasing.
2. Halogen lamp
The halogen lamp can be regarded as an upgraded version of the incandescent lamp.
Halogen bulb (English: halogen lamp), referred to as halogen bulb or halogen lamp, also known as tungsten halogen bulb, quartz bulb, is a variant of incandescent lamp. The principle is to inject halogen gas such as iodine or bromine into the bulb. At high temperature, the sublimated tungsten wire reacts with the halogen. The cooled tungsten will re-solidify on the tungsten wire to form a balanced cycle to avoid premature fracture of the tungsten wire . Therefore, halogen bulbs have a longer life than incandescent lamps (almost 4 times that of incandescent lamps), and at the same time, because the filament can work at a higher temperature, thereby obtaining higher brightness, higher color temperature and higher luminous efficiency.
As an upgraded version of incandescent lamps, halogen lamps have all the advantages of incandescent lamps: the color light is closest to the color of sunlight, the color rendering is good, the spectrum is uniform and not abrupt. However, halogen lamps also inherit the shortcomings of incandescent lamps: short life (although they are longer than incandescent lamps), low luminous efficiency (although they are higher than incandescent lamps), and because halogen lamps are also thermal radiation light sources, they are turned on or just after the lamp is turned off Because the lamp temperature is still very high, never touch it by hand.
In addition, incandescent lamps and halogen lamps have a small amount of ultraviolet (UV) and infrared (IR) radiation problems. If you want to achieve the ideal eye protection color, you must use a high-power bulb, so infrared heat is large and used for a long time at close range, it is easy to cause facial skin problems, plus ultraviolet radiation, may even lead to extreme conditions such as sun dermatitis . Therefore, if you want to use a halogen lamp as a light source for a desk lamp, at least UV protection treatment is required-in simple terms, the part of the lamp cap that is best to have a layer of frosted or partially frosted and UV-resistant glass panel.
3. Ordinary fluorescent lamp
The long tubes we used when we were kids were fluorescent lamps, also known as fluorescent lamps. The traditional fluorescent lamp, that is, a low-pressure mercury lamp, uses the principle of low-pressure mercury vapor to release ultraviolet rays after being energized, so that the fluorescent powder emits visible light to emit light. Therefore, it belongs to a low-pressure arc discharge light source.
Ordinary fluorescent tubes are coated with halogen fluorescent powder and filled with a mixture of argon and krypton argon. The light color is: cool white daylight fluorescent tube, warm white daylight fluorescent tube. Although fluorescent lamps are less hot than incandescent lamps and have a much higher luminous efficiency, these two light-color fluorescent tubes have lower color rendering performance and a color rendering index R value of less than 40. Far less than the standard value of sunlight, color rendering index R = 100. Look at the color of the surface of a colored object to produce a color cast. The color is greenish or grayish, and the color is dim and not bright. These two fluorescent lamps are not high-efficiency and energy-saving electric light sources, and do not meet the technical requirements of green lighting.
Common light sources for table lamps rarely use ordinary fluorescent lamps, so they are simply omitted.
4. Energy-saving lamps (CFL lamps)
The name energy-saving lamp is widely abused in electric light sources other than incandescent halogen lamps, such as the word 'LED energy-saving lamp' that can be seen everywhere. The energy-saving lamp mentioned here is a compact three-color electronic fluorescent lamp (abbreviated as CFL lamp abroad), which is a compact fluorescent lamp with a ballast.
In detail, the CFL lamp is a single-end compact energy-saving fluorescent lamp. The tube, ballast and base of this fluorescent lamp are tightly integrated (the ballast is placed in the base), except for the devastating blow, they cannot be disassembled, so it is called a 'compact' fluorescent lamp. Since no external ballast is needed, the driving circuit is also in the ballast, so this fluorescent lamp is also a self-ballasted fluorescent lamp and an internal start fluorescent lamp. The whole lamp is directly connected to the power supply network through the E27 and other lamp caps, which can easily replace the incandescent lamp directly. Most of these fluorescent lamps use rare earth element three-primary phosphors, so they have energy-saving functions, so they are called 'energy-saving lamps'.
Energy-saving lamps are smaller in size, save energy than incandescent lamps, and have a longer lifespan than incandescent lamps. However, the disadvantages are also obvious: as a type of fluorescent lamp, mercury is added to the lamp tube, and the environmental pollution caused by the current recycling mechanism cannot be ignored without a good recycling mechanism. In addition, the ballast used in energy-saving lamps will produce certain electromagnetic radiation when it generates instantaneous high voltage.
As a light source for desk lamps, the most critical issues with CFL lamps are color temperature and color rendering. This will be covered in a later series of articles.
5. LED lights
LED is the abbreviation of English light emitting diode (light emitting diode). A light-emitting diode is a solid-state semiconductor device that can convert electrical energy into visible light. It can directly convert electricity into light.
The heart of the LED is a semiconductor chip. One end of the chip is attached to a bracket, one end is the negative electrode, and the other end is connected to the positive electrode of the power supply, so that the entire chip is encapsulated by epoxy resin. The semiconductor wafer is composed of two parts, one part is a P-type semiconductor, in which holes are dominant, and the other end is an N-type semiconductor, where mainly electrons. But when the two semiconductors are connected, a PN junction is formed between them. When electric current acts on the chip through the wire, the electrons will be pushed to the P region, where the electrons recombine with holes, and then emit energy in the form of photons, which is the principle of LED light emission.
Because LED lamps do not generate much heat and convert electrical energy into light energy as much as possible, LEDs are often also called 'LED energy-saving lamps.' When buying energy-saving lamps, be sure to distinguish between two completely different light sources, LED and CFL.
Also known as energy-saving lamps, compared with CFL lamps, LED lamps are environmentally friendly and do not contain mercury, and can be recycled and reused. This is probably a major driving force for countries to vigorously develop LED lamps.
LED lights have many advantages, and the main points placed on the table lamp light source are the following:
①Green and environmental protection: small glare, no radiation, no harmful substances in use.
②Long life and stable performance, there are no shortcomings such as filament glow easily burnt, thermal deposition, light decay and so on.
③Multi-transformation: LED light source can use the principle of three primary colors of red, green and blue, under the control of computer technology to produce different colors, intensity and color temperature. ——This is very important under different usage environments and light backgrounds.