Overview
Light-emmitting diode, abbreviated led, is a light-emitting semiconductor electronic component that combines light through a triple price with a pentavalent element. As early as 1962, such electronic components were capable of delivering only low-light red light, which hp had acquired the patent and used it as a beacon. Other monochromic versions were developed, and so far the light that can be released has spread to visible, infrared and ultraviolet light, and has increased to a considerable degree. With the advent of the white light luminous diode, applications have evolved from those indicated in the initial light and display panels to those in recent years。
Three different colours of leds
The luminous diodes can only conduct (electricity) in one direction, known as positive bias, when the current is out of date and the electrons and the hollows are composited within them and send a single colour of light, which is called electric light, and the wavelength and colour of the light is associated with the type of semiconductor material it uses with the elemental impurities that are intentionally mixed. They have the advantage of being efficient, long-lived, non-vulnerability, fast reaction, and highly reliable traditional sources of light. The light efficiency of white light leds has improved in recent years; the cost of per thousand per thousand is lower, also because of a large investment of funds, but the cost is still much higher than other traditional lighting. Nevertheless, there has been an increasing use of lighting in recent years。
On the basis of “the invention of high-light blue light diodes, which brought a white source of energy-efficient and bright light”, in 2014 amano received the nobel prize for physics, together with akakazaki and shuji nakamura。
History and development
In 1961, the united states company robert biard, a texas instrument, and gary pittman first discovered infrared radiation from arsenic and other semiconductor alloys. In 1962, nick holenark, general electric, developed the first visible photoluminescent diode that could be applied in practice。
In 1993, hiroshi nakia chemical industries in japan successfully mixed magnesium into the production of a blue lighted diode based on a wide energy gap semiconductor material (ingan), which has commercial applications. As a result, shuji nakamura won the nobel prize for physics in 2014, working with amano and akazaki. Some commentators argue that it is not fair for the nobel prize to skip red, green led inventors. However, per delsing (professor chalmers university of technology, sweden), chairman of the nobel committee (physics prize), who argued in his interview in read and sell news that “after carefully studying the contribution of inventions, he was confident that the three individuals would be awarded the award”。
Led light bulbs with aluminium radiators
With the blue-lighted diodes, the white-lighted diodes came to light, and the leds then moved in the direction of increased light, when the average leds were working with less than 30 to 60 mw. The commercialization of leds with input power of 1 w (w) in 1999. These luminous diodes deal with high-energy input with very large semiconductor chips, which are attached to metal chips to help spread heat。
In 2002, the emergence of 5w luminous diodes began in the market, with an efficiency of about 18-22 lm per watt。
In september 2003, cree, inc. Demonstrated its new version of the blue-lighted diode, with 35 per cent efficiency under 20 mw. They also produced a white light-luminous diode commodity of 65 lm/w (per watt) which was the brightest white light-luminous diode in the market at that time. In 2005, they demonstrated a white light-luminous prototype of the diodes, with a record efficiency of 70 lm per watt under 350 mw。
In february 2009, japan's led plant japan, japan's led industry, published leds with high efficiency of 249 lm/w, which are laboratory data。
In february 2010, philips lumileds built a white led in a controlled laboratory environment that produced 208lm/w under standard test conditions and driven by 350ma electric currents, but was unable to know its power because the company did not disclose the current bias。
In april 2012, the u. S. Luminous diode plant (cree) introduced 254 lm/w photolyse to rewire power。
Old works much less efficiently than the general luminous diodes, with the highest rates being only around 10 per cent. However, oled production costs are much lower, for example, by simply printing large oled arrays that can be placed on screens to create colour screens。
Rationale
Led is a special diode. As with ordinary diodes, the luminous diodes consist of semiconductor chips that pre-form p, n structures through processes such as injection or mixing. As with other diodes, currents in luminous diodes can easily flow from the p pole (anode) to the n pole (cathode), but not in the opposite direction. Two different streams: hollows and electronics flow from electrodes to p, n structures with different electro-polar voltages. When holes and electrons come into contact, electrons fall to lower energy levels, and they release energy in photons (the photons are also what we call light)。
Spectrum characterization curves combining blue, yellow and green, and bright red luminous diodes, with a bandwidth of about 24 nm - 27 nm in the fwhm spectrum
The wavelength (colour) of the light it emits is determined by the inhibited energy of semiconductor material forming the p, n structure. Since silicon and thorium are indirect cleavage materials, the combination of electrons and hollows in these materials is a non-radiogenic leap at constant temperatures, which does not release photons but transforms energy into thermal energy, so that silicon and thorium diodes do not glow (which light at a specific temperature at very low temperatures, must be detected at a special angle and the light of the light is not visible). The materials used for the luminescent diodes are of a direct lacuna type and thus the energy is released in the form of photons that correspond to the light energy of near infrared, visible light or near ultraviolet bands。
In the early stages of development, only infrared or red light can be launched from the luminous diodes using gaas. With the advances in material science, the successful development of the luminescence diodes can emit increasing light waves. Today, light diodes of all colours are available。
The diodes are normally constructed at the base of the n-type liner, which deposits a layer of p-type semiconductor on its surface and is connected together with electrodes. The p-line is less common but is also used. Many commercial leds, especially the gan/ingan, also use sapphire liners。
Most of the substances used to make leds have very high refraction rates. This means that most light waves are reflected back into the substance at the interface between the substance and the air, so that light-wave extraction is an important topic for the luminous diodes, on which much research and development is focused。
Here are the inorganic semiconductor raw materials for the luminous diode and the light colours:
Use visual messages to show strengths and weaknesses
The driving power and low power required for leds is easily controlled by low-pressure microprocessors and used on battery-based equipment, so they are often used in state lamps for various electronic products and equipment. Working-status lamps are displayed for consumer electronics, portable embedded electronics, household appliances, toys, instruments, etc。
Led traffic sign led lighting
Because lighted diode lamps are called solid lighting. Traditional lighting lamps, such as fluorescent lamps, incandescent lamps and halogen lamps, have fragile glass tubes that contain gas and are therefore not fully solid and durable. The existing single large power-emitting diodes typically consist of 1w, 3w, 5w, etc. Some led lamps combine multiple white light leds into one light source to increase efficiency, as the efficiency of the light-emitting diodes is reduced when they increase light; similarly, they are only used for lighting where light requirements are low to maintain their relative efficiency (saving electricity)。
Use led 's surefire u2-hand narrow-band optical sense device
Visible photoluminescent diodes and photodetectors are pn knots that use a gap in the visible light band and therefore have many of the same physical properties, while the application of the photoluminescent diodes to light detection is a technology that has long been known, but until recently, the two-way luminous diode arrays were proposed and applied to contact sensors (touch-sensing). In 2003, a paper by dietz, yerazunis and leigh described how to apply the luminous diode as a cheap test element。
In this application, each luminous diode in the array is quickly lighted and extinguished. After lighting the luminous diode, the light is irradiated to the operator's finger or pattern, the reflecting light is then detected by the luminous diode in the extinguishing state, and on the luminous diode in the reverse bias, the voltage is felt, and the size of the sensor is then read out through the microprocessor, and jeff han's website provides a video showing the operation of the luminous diode array detector。
