What is led screen, what is blister?
Author:Guo Wei Time:2021-06-08 10:37 Browse(628)
The LED screen is a new type of imaging electronic equipment which is made of light-emitting diodes arranged in order.
LED screen is a new type of imaging electronic equipment, which is made of light-emitting diodes arranged in order1、 Structure and luminous principle of LED[edit this paragraph]Fifty years ago, people already knew the basic knowledge that semiconductor materials can produce light.
the first commercial diode was produced in 1960.

What is led screen, what is blister?

LED is the abbreviation of light emitting diode in English.
its basic structure is an electroluminescent semiconductor material, which is placed on a shelf with leads, and then sealed with epoxy resin to protect the inner core wire, Therefore, the LED has good seismic performance.
the results show that the LED has good seismic performanceThe core of light-emitting diodes (LEDs) is a wafer composed of p-type and n-type semiconductors.
there is a transition layer between p-type and n-type semiconductors, which is called p-n junction.
in some PN junctions of semiconductor materials,
when the injected minority carriers combine with the majority carriers, the excess energy will be released in the form of light, In this way, the electrical energy can be directly converted into light energy.
the PN junction is applied with reverse voltage.
a few carriers are difficult to inject, so they do not emit light.
this kind of diode based on the principle of injection electroluminescence is called light-emitting diode.
it is generally called led.
when it is in the forward working state (that is, the forward voltage is applied at both ends).
when the current flows from the anode to the cathode of the LED, Semiconductor crystals emit different colors of light from ultraviolet to infrared, and the intensity of light is related to the current2、 Characteristics of LED light source[edit this paragraph]1. Voltage: LED uses low-voltage power supply.
the power supply voltage is between 6-24 V, which varies according to different products, so it is a safer power supply than using high-voltage power supply, especially suitable for public places.
the power supply voltage of LED is between 6-24 v2. Efficiency: energy consumption is 80% less than that of incandescent lamp with the same luminous efficiency3. Applicability: very small.
each unit led chip is 3-5mm square, so it can be fabricated into various shapes of devices, and it is suitable for the changeable environment.
14. Stability: 100 000 hours.
the light decay is 50% of the initial value.
25. Response time: the response time of incandescent lamp is millisecond level.
the response time of LED lamp is nanosecond level.
the response time of LED lamp is nanosecond level6. Environmental pollution: no harmful metal mercury7. Color: changing the current can change color.
light emitting diodes can easily adjust the energy band structure and band gap of materials through chemical modification to achieve red, yellow, green, blue and orange multi-color luminescence.
for example, red LED can be used at low current.
with the increase of current, it can be changed into orange, yellow, and finally green8. Price: the price of LED is more expensive.
compared with incandescent lamp, the price of a few LEDs can be equivalent to that of an incandescent lamp, and usually each group of signal lamp is composed of 300-500 diodes.
the price of LED is higher than that of an incandescent lamp3、 Types and development history of monochromatic LED[edit this paragraph]The first LED light source based on the principle of semiconductor p-n junction was made in the early 1960s.
the material used at that time was GaAsP.
emitting red light( λ When the driving current is 20 mA, the luminous flux is only a few thousandths of lumen, and the corresponding luminous efficiency is about 0.1 lumen / W.
the experimental results show that the luminous efficiency is about 0.1 lumen / WIn the mid-1970s.
elements in and N were introduced to make LED produce green light( λ P=555nm), yellow light( λ P=590 nm) and orange light( λ The light efficiency was also increased to 1 lumen / WAt the beginning of 1980s, GaAlAs LED light source appeared, which made the light efficiency of red LED reach 10 lumen / W.
in recent years, LED light source of GaAlAs has been widely usedIn the early 1990s, the development of red and yellow emitting GaAlInP and green and blue emitting GaInN has greatly improved the light efficiency of LED.
in 2000, the LED made of the former was in the red and orange region( λ The light efficiency of the LED is 100 lumen / w (P=615nm)( λ The light efficiency can reach 50 lumen / W.
the results show that the light efficiency can reach 50 lumen / W4、 Application of monochromatic LED[edit this paragraph]At first, led was used as the indicator light source of instruments and meters.
later, led with various light colors was widely used in traffic lights and large area displays, resulting in good economic and social benefits.
take 12 inch red traffic lights as an example.
in the United States, 140 watt incandescent lamps with long life and low light efficiency were originally used as the light source, It produces 2000 lumens of white light.
after passing through the red filter.
the light loss is 90%, leaving only 200 lumens of red light.
in the new design of the lamp.
Lumileds company uses 18 red LED light sources, including circuit loss, which consumes 14 watts of power, and can produce the same light efficiency.
in the new design of the lamp, Lumileds company uses 18 red LED light sourcesAutomobile signal lamp is also an important field of LED light source application.
in 1987, China began to install high mounted stop lamp on automobiles. Due to the fast response speed (nanosecond level) of LED, it can let the driver of the following vehicle know the driving condition as soon as possible, and reduce the occurrence of rear end collision accidents.
in this paper, the development trend of high mounted stop lamp is introducedIn addition.
LED lights are used in outdoor red, green and blue full-color displays,Keychain micro torches and other fields have been applied5、 Development of white LED[edit this paragraph]For general lighting.
people need white light source more.
in 1998, white LED was successfully developed.
this kind of LED is made of Gan chip and yttrium aluminum garnet (YAG) packaged together.
Gan chip emits blue light( λ The blue LED substrate is mounted in a bowl shaped reflecting cavity.
it is covered with a thin layer of resin mixed with YAG, about 200-500nm.
part of the blue light emitted by the LED substrate is absorbed by the phosphor.
another part of the blue light is mixed with the yellow light emitted by the phosphor, White light can be obtained.
for InGaN / YAG white LEDs, by changing the chemical composition of YAG phosphor and adjusting the thickness of phosphor layer, white light with a color temperature of 3500-10000k can be obtained.
in this paper, the color of InGaN / YAG white LEDs is analyzedThe types and luminescent principles of white LEDs are listed in Table 1.
at present, the first product that has been commercialized is blue light single crystal chip with YAG yellow phosphor.
its best luminous efficiency is about 25 lumen / W, and YAG is mostly imported from Nippon Yat Sen, with a price of 2000 yuan / kg; The second is the white LED made of ZnSe developed by Sumitomo, but the luminous efficiency is poorIt can also be seen from the table that some kinds of white LED light sources cannot do without four kinds of phosphors: three primary colors of rare earth red, green, blue and garnet structure of yellow,It is expected that three wavelength white LED will be commercialized this year.
however, the particle size requirement of three color phosphor here is relatively small.
the stability requirement is also high, and the specific application is still under exploration. to form white LED3 blue LED green LED red LED InGaN AlInGaP encapsulates three kinds of chips with three primary colors to form a white LEDMultiple LED InGaN and gap AlInGaP with multiple light colors package various optical chips throughout the visible region to form white LEDUsing LED light source for lighting, first replace the power consuming incandescent lamp, and then gradually enter the whole lighting market, will save a lot of power.
White LED has reached a single power consumption of more than 1 watt, light output of 25 lumens, which also increases its practicability.
Table 2 and table 3 list the performance progress of white LED.
Table 2 shows the performance progress of single white LEDAnnual luminous efficiency (lumen / watt) remarks1998 5199 15 similar incandescent lamp2001 25 phase tungsten halogen lamp2005 50 estimateTable 3 long term development goal single white LEDInput power 10 wattsLuminous efficiency 100 lumen / WOutput light energy 1000 LM / W6、 Industry profile[edit this paragraph]In the LED industryNichia is the first to use the above technology to develop high brightness LED with different wavelengths, and laser diode with blue violet light; After Nichia chemical obtained many basic patents, such as blue LED production and electrode structure, etc.
it insisted on not providing external authorization, only adopting its own production strategy, with the intention of monopolizing the market, which made the price of blue LED high.
however, other manufacturers with production capacity did not think so.
some Japanese LED manufacturers believed that the price of blue LED was high, The strategy of Nippon Yat Sen Chemical Co., Ltd. will make Japan win the lead in the competition of blue and white LED, which will cause serious damage to the overall Japanese LED industry.
therefore, many companies will try their best to develop and produce blue LED.
at present, besides Nippon Yat Sen Chemical Co., Ltd. and Sumitomo Electric Co., Ltd.
there are also Toyota synthetic, Luomu, Toshiba and sharp, American Cree, The world's three major lighting factories, such as Qiqi, Philips, OSRAM, HP, Siemens, research and Emcore, have all invested in the R & D and production of the product, which has played a positive role in promoting the industrialization and marketization of white LED products.
in this paper, the development of white LED products is reviewedBlisterOpen classification: industry, plastics, packagingIt is a kind of plastic processing technology.
the main principle is to heat and soften the flattened plastic hard sheet, absorb it on the surface of the mold by vacuum, and then form it after cooling. It is widely used in plastic packaging, lighting, advertising, decoration and other industriesBlister packaging: the general term of plastic products produced by blister technology and packaged by corresponding equipment.
this paper introduces the blister packaging technology of plastic productsBlister packaging products include blister shell, tray and blister box.
synonyms include vacuum hood, blister, etc.
the blister packaging products include blister shell, tray and blister boxThe main advantages of blister packaging are.
saving raw and auxiliary materials, light weight, convenient transportation and good sealing performance, which meet the requirements of environmental protection and green packaging; It can pack any special-shaped products without additional cushioning materials; The packaged products are transparent and visible, beautiful in appearance, easy to sell, suitable for mechanized and automatic packaging, convenient for modern management, saving manpower and improving efficiencyBlister packaging equipment mainly includes: Blister molding machine, punch, sealing machine, high frequency machine, folding machineThe packaging products formed by packaging can be divided into: insert card, suction card, double foam shell, half foam shell, half fold foam shell, three fold foam shell, etc.
the packaging products formed by packaging can be divided into: insert card, suction card, double foam shell, half foam shell, half fold foam shell, three fold foam shell, etc
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