Glow diode, call LED normally, it is the truly anonymous hero inside electronics world. They made a lot of different jobs and the presence that can see it in various facilities.

 

 

What is diode?

 

Diode is one of semiconductor equipment the commonnest parts of an apparatus, most semiconductor is most by mingle semiconductor material to be made (atom and other material) , material of glow diode conductor is aluminous arsenic changes sow normally, sow is changed in aluminium arsenic in, the with them neighbour with all perfect atom is united in wedlock, did not keep electric current of free electron join.

 

In mingling material, additional atom changes report to balance, not be the cavity that increases free electron to create an electron to be able to be passed namely. The requirement with this additional different makes material provides conductibility more.

 

The semiconductor that takes additional electron is called N semiconductor, because it contains particle of additional negaive electricity, it is so in N semiconductor material, free electron is from negaive electricity area flows to positive electricity area.

 

The semiconductor that takes ” of cavity of additional “ electron is called P semiconductor, because contain positive electricity particle. The electron can jump to another electron cavity from another electron cavity, from flow to positive electricity area from negaive electricity area.

 

Diode is by N semiconductor material and P semiconductor material is united in wedlock, every end takes an electron. Such permutation make electric current can flow from a direction only.

 

When passing diode without voltage, electron along transfer the confluent place between the layer flows to P semiconductor from N semiconductor, form division of a loss thereby.

 

In loss area, semiconductor material can reply its insulation condition —— before all ” of these “ electron cavity are met by cram, all do not have free electron or electronic vacuum division and electric current to cannot flow.

 

 

To get rid of loss area must make N should move reversely to P shift and cavity. To achieve a goal, a join diode N negative pole to electric current and P arrive with respect to join voltaic anode.

 

The free electron in N material can be repelled by negative pole electron and attract positive electrode electron at this moment. The electronic cavity in P material with respect to tend another direction.

 

It is when voltage between the electron enough tall when, will counteract in its electronic cavity in the electron of loss area begin free shift again. Loss area disappears, electric current passes diode.

 

 

If try to make electric current flows to other direction, p end receives voltaic negative pole and N join to arrive with respect to the edge positive electrode, at this moment electric current will not flow. The negative pole electron of N material is attracted positive electrode electron.

 

The cavity of positive electrode electron of P material is attracted negative pole electron. Do not have voltaic shedding to carry confluent part so to wrong directional shift because of electronic cavity and electron, loss area increases.

 

Why can glow diode give off light?

 

When Pn knot two end make good electrode after derivative pin has been enclosed, formed a diode. The character of diode is main the character that is Pn knot, some using as rectification, some uses demodulation, some can give off light; These just are of parameter adjust or the change of material, its fundamental is identical.

 

 

Light is a kind of form of energy, one kind can be released by atom. Be by a lot of having energy and motivation but like the tiny particle that does not have quality of bunches of small composition. These particle are called photon, it is optical the mainest unit. Because electrovalence just is released,photon is. The electron is having in different course function different the energy that wait.

 

 

Add when the two end of diode to bias voltage, major voltage is added to space charge area. At this moment voltage drop of built-in electric field is small, broke carry stream child diffuse to balance adrift: P area cavity diffuses to N area, N area electron diffuses to P area, equivalent gives N area infuse hole at adscititious electric field, give P area infuse electron.

 

The cavity of infuse N area is very fast photon of as compound as the electron radiate, the electron of infuse P area is very fast also photon of as compound as hole radiate, pn knot plays ceaseless glow in the action of electric field. Outer add to voltage very hour, infuse carries stream child the quantity is dinky, the flesh is less than the light that give out soon;

 

Meeting abundantly infuse carries the ability when be close to when extra voltage only or exceeding voltage of built-in electric field stream child, can see diode gives out bright light so.

 

To glow diode, the electron that needs infuse and cavity as soon as possible compound, the proportion that compound electric current holds total electric current gives off light greatly more efficiency is taller, let light energy of translate into of ground of electric energy more is not heat energy; And the electron that common diode needs infuse commonly and cavity as far as possible little ground is compound.

 

Free electron falls into empty electronic cavity through diode from P layer. This is included from pass conduction band to decline to a lower course function, so the electron releases energy with photon form namely. This can happen in any diode, in common diode, semiconductor material itself draws much light energy and end.

 

 

The English abbreviation of glow diode is LED. The glow diode of all sorts of color can see in the life, some sends green light, some is aglow, some sends La Guang, glow, return some hair sightless infra-red with ultraviolet light.

 

So, the light that what decided to diode sends different color be? Take to valence from conduction band transition when an electron with respect to meeting radiate a photon, the energy E of this photon is equal to Eg of forbidden band width, and the wavelengh λ=1.24/Eg(μm) of photon, so the forbidden band width of semiconductor decided the color that diode gives off light basically.

 

The Bai Guang that diode of white smooth glow gives out is not monochromatic light, mix by a variety of light however and become. What diode of common white smooth glow uses is nitrogen turns gallium semiconductor material, width of its forbidden band makes an appointment with 3.39eV, what formation Pn tie sends is La Guang (already adjusted through foreign matter energy level photon energy) . But, besmear has white of a Huang Guangying light outside the Pn knot in diode, hit to yellow glossy fluorescent material when La Guang hind, glow diode gives out the Bai Guang that yellow La Guang mixes and becomes.

 

The development course of glow diode

 

1907, british Ma Keni (PN knot is in the semiconductor of inference of first time of scientist Henry Round of Marconi) lab light can be given out below certain condition. This discovery laid the physical foundation that LED is invented.

 

1927, russia scientist Ao Liefu pulled Jiluoxiefu to make the first LED independently, the science that its study to achievement ever was in Russian, Germany and England early or late is published on the magazine, there is not person pay attention to at that time regrettablly he.

 

 

1955, lang Shitai of cloth of · of physicist Lu Bin discovered American radio company first the glow that the infra-red and radiative intention that arsenic changes alloy of gallium etc semiconductor realized diode on physics, the light that gives out regrettablly is not visible light however infrared ray, but this contribution is very large also.

 

1961, company of heart state apparatus (TI) · Pitman discovers heart of Lai of cloth of scientist Bob · and Gary arsenic changes gallium to be in bring to bear on the meeting when the electron flows releases infra-red ray radiation. The infra-red LED that they led a gentleman to yield to be used at commercial use obtained arsenic to change gallium the invention of infra-red diode is patent. Before long, infra-red LED is applied extensively among Yu Chuangan and photoelectricity equipment.

 

1962, american General Electric Company (GE) a · of common researcher Nick why Lun Yake invented the LED that can give out red visible light, the father ” of diode of glow of the “ that be called, also won N much award later. The LED at that time returns a hotshot labour to make, and every price needs 10 dollars. 1963, he leaves General Electric Company, taking up the post of project of electric machinery of university of Nuo of benefit of Yi of United States of its alma mater is a professor, foster oneself successor.

 

1972, why student George · of Lun Yake overcomes Laofude to stepping elder people the footstep invented LED of Huang Guang of the first orange, its brightness is 10 times of glow LED more previous, this mark is worn LED faces the first situation that improves glow efficiency direction to be stridden.

 

20 centuries 70 time evening, LED had appeared the color such as red, orange, yellow, green, verdure, but the LED that still does not have blue and white shade. Because only the invention gives La Guang LED to just may realize complete color LED to show, vendibility is tremendous, also be at that time tackle key problem cosmopolitanly difficult problem. Scientists turn and put the emphasis in the glow efficiency that improves LED above.

 

20 centuries 70 time metaphase, when LED can produce light of green, yellow, orange, glow effect is 1 lumen / made of baked clay, arrived 80 time metaphase is opposite 20 centuries the use that arsenic changes gallium and phosphor to melt aluminium makes generation tall brightness red, yellow, green shade LED is born, glow efficiency already achieved 10 lumen / made of baked clay.

 

1993, the village is repaired in 2 in Japanese day inferior during chemical industry company limited assumes office, use semiconductor material nitrogen to change gallium (GaN) changed sow to invent La Guang LED with indium nitrogen, before La Guang LED appears, because cannot pass RGB system to synthesize Bai Guang, the smooth effect of LED, brightness is not tall also, LED cannot apply at illume domain.

 

Because this is repaired in the village in 1995 2 use indium nitrogen to changed sow to invent green smooth LED again, red, green, La San was used to plant 1998 LED makes Cheng Baiguang LED, from now on green light and development of Bai Guang LED are successful, the mark is worn domain of illume of LED make one’s bow, it is the milepost with LED illume the most crucial development. The father ” that the village repairs LED of La Guang of the 2 “ that be called, green light, Bai Guang in

 

1996, day inferior the invention patent of the Bai Guang LED that chemical company declares the earliest in Japan is namely on chip of La Guang LED fluorescent material of yellow of besmear Fu YAG, the Huang Guang that after the La Guang that gives out through chip and fluorescent material are activationed, gives out is complementary and form Bai Guang. Of blue and white lubricious smooth LED appear widened the applied domain of LED, make complete color LED shows, the application such as LED illume becomes a possibility.

 

 

At the beginning of 21 centuries, the light that LED can have given out any visible and spectral color (still include to have infrared ray and ultraviolet ray) . Its glow efficiency has achieved 100 lumen / made of baked clay above.

 

Of glow diode

 

Advantage and defect

 

The advantage of LED basically has:

 

1, energy-saving, more energy-saving than incandescent lamp 80% above, more energy-saving than energy-saving lamp 50% above.

 

2, volume is minor, weight is light, do not be afraid of shake.

 

3, smooth effect is tall, it is 8 times of incandescent lamp 15m/w, be fluorescent lamp 50 Lm/w 2 times much.

 

4, smooth lubricious optional choose, the glow color of LED illuminant and colour temperature OK and agile application.

 

5, . Directional good, LED glow angle can be adjusted neatly.

 

6, environmental protection: Wait for harmful material without the mercury that energy-saving lamp place contains.

 

7, . Cold light source does not have ultraviolet ray and infrared ray, reason does not have quantity of heat, without radiation.

 

8, life is long, life can be amounted to 50 thousand – times above of 100 thousand hours of longer than life of traditional light source 10-50.

 

9, . Answer speed fast, accept second class.

 

The defect of LED basically has:

 

1, . Medicinal powder hot issue, LED sends energy of the additionally one part in smooth process to be changed into quantity of heat in report, if cannot send out in time,go out, the knot that PN writtens guarantee is lukewarm will lift, quickly chip and enclose resinous ageing, make chip invalidation, affect the service life of LED and glow performance.

 

2, waterproof properties is poor, it is outdoors oxidation of metal of the interior after interior of use illuminant of a the heel of Achilles is bibulous affects output or generation internal stress, fluorescent material sucks tide to become angry, smooth lubricious drift.

 

3, cost is higher. Illuminant. Radiator. Power source. Appear chimney high / lens / reflection cover. 4 person cost collective pushs tall LED cost.

 

4, . Need driver provides constant current power source, driver life is the main factor that affects life of lamps and lanterns.

 

5, semiconductor device, more sensitive to electrostatic influence, be writtened guarantee easily cause leakage current or dead light by electrostatic puncture PN.

 

The sort of glow diode

 

1, by glow tubal glow color divides:

 

By glow tubal glow color can be divided into gules, orange, green (fractionize olivine, standard is green and pure green) , La Guang.

 

Additional, 2 kinds are included in some glow diode or the chip of 3 kinds of color. Give light to be in mix into according to glow diode or not agent of mix into scattering, coloured is colorless still.

 

Afore-mentioned glow diode of all sorts of color still can be divided into coloured scattering of colorless and transparent, transparent, coloured and colorless scattering 4 sort. Scattering glow diode and amount to use at making indicator light.

 

2, by glow canal feature of face giving light divides:

 

By glow the canal gives smooth face feature to be able to divide the circle that it is cent installation of canal of glow of the lamp, Fang Deng, rectangular, face, side direction canal, surface uses miniature canal to wait. Circular lamp is φ2mm, φ4.4mm, φ5mm, φ8mm, φ10mm and φ20mm to wait by diametical cent. Abroad writes down the  glow diode of φ3mm normally T-1; φ5mm write down T-1 (3/4) ; φ4.4mm write down T-1 (1/4) . By half value horny size can estimate distributinging circumstance of horn of circular glow intensity.

 

From glow intensity horn distributinging graph divides have 3 kinds:
 

(1) tall directivity. Enclose for cusp annulus oxygen commonly, or it is to take a metal to reflex antrum to enclose, and do not add scattering agent. Half value horn is 5° ～ 20° or smaller, have very tall directivity, can make local lighting illuminant use, or with smooth detector couplet in order to forms automatic testing system.

 

(2) standard type. Make indicator light use normally, its are worth horn to be 20° ～ 45° partly.

 

(3) scattering. This is the indicator light with bigger perspective, half value horn is 45° ～ 90° or bigger, the amount of scattering agent is larger.

 

3, the structural cent that presses glow diode:

 

The structure that presses glow diode can be divided cover for complete ring oxygen, oxygen of metallic base annulus is enclosed, oxygen of annulus of base of pottery and porcelain is enclosed reach glass to enclose wait for a structure.

 

4, divide by glow intensity and working electric current:

 

The LED that can divide the well-illuminated that it is general to spend by glow intensity and working electric current (glow intensity <10mcd) ; The LED of freeboard brightness (glow intensity > 100mcd) ; Be in glow intensity between 10 ～ 100mcd call tall brightness glow diode.

 

The working electric current of general LED comes in ten MA a few MA, and the working electric current of LED of small electric current is under 2mA (brightness and common glow valve are same) .

 

Normally, according to the structure, LED can divide for the following 4 kinds big:

 

One, the straight LED that insert type
 

1, dimension has: 3Mm, 5mm, 8mm, 10mm;

 

2, color: Red, green, blue, yellow, orange, olivine, white, purple waits;

 

3, colloid color has: Colorless and transparent, coloured is scattering of transparent, coloured, colorless scattering

 

4, application: Of electric home appliances<gj insert the lamp, LED to display screen continuously, outdoors look board, lamp of inside and outside of public LED street lamp, car.

 

 

 

2, SMD surface sticks outfit diode

1, dimension has: 2835, 3014, 3528, 4014, 5050, 5630 wait;

 

2, color has red, green, blue, yellow, amber, olivine, white, purple to wait;

 

3, colloid color has: Colorless and transparent, coloured is scattering of transparent, coloured, colorless scattering;

 

4, . Apply: ? Zhui river rotten Su clear Jian by Gu rare?

 

 

3, maneating fish (FLUX LED)

 

1, maneating fish encloses modular bead to have φ3mm round head and φ5mm circle head, also have sunken model the crop appearance of appearance. The basis gives the demand of smooth angle, can choose all sorts of enclosing modular bead;

 

2, color has red, green, blue, yellow, amber, olivine, white, purple to wait;

 

3. colloid color has: Colorless and transparent, coloured is scattering of transparent, coloured, colorless scattering;

 

4, in the illuminant in chamfer of body of the lamp case that maneating fish LED suits to make light source of line lamp, back very much, big character and car illume.

 

 

4, high-power LED(Power Led)

 

1, high-power has 1W, 3W, 5W, 10W to wait;

 

2, color: By semiconductor PN knot oneself produces color, sterling, grumous; Colour abounds —— 3 base lubricious addend piles up a technology, can evolve into aleatoric colour;

 

3, high-power LED is decorated in the special industry such as oil field, petrifaction, railroad, mine, army, arena, urban landscape illume, indication screen and stadium house, lamps and lanterns of special type job has wide applied perspective mediumly.

 

 

 

 

The applied domain of glow diode

 

With the market is told now, LED product basically is to be centered in indication domain, illume domain, pass feeling domain and the domain that print.

 

Indication domain

 

 

1, electronic instrument indicator light, be in a poor light etc

 

It is before early, the utility of LED is the indicator light that replaces electronic instrument. Why is this such reason? Because the indicator light effect of electronic instrument has a very strict level,basically be, that is durability tall. At that time, the durable sex of incandescent lamp can not compare a gender than LED product, so LED replaced the intention that the electronic instrument of incandescent lamp indicates very quickly.

 

The time 1980 paragraph, LED product is to belong to high-tech product at that time, so the price is very expensive. In smooth lubricious respect, have red only, and brightness still is not very bright, so the indicator light of instrument of a lot of electrons still uses diminutive blue, green, with white incandescent lamp.

 

Begin from 1990, the technical level of LED got a very big promotion, white LED also is in the production of batch, the product that so the indicator light in electronic instrument introduces LED is more.

 

2, electronic board monitor

 

 

Earlier 1990, LED product is useful in call-board, but only a kind of color can choose at that time, it is orange, and brightness is very low still. Be in so at that time, LED call-board can be used indoors only.

 

In this time paragraph later, LED produces technical promotion, the scientific staff that studies LED develops the glow LED that gave tall brightness successfully, begin from this moment, with respect to the place that can begin days to be spent brightly use LED shows board.

 

This LED shows board have apparent energy-saving effect, compare traditional TV wall, the indication of colorful neon lamp is compared, LED not only energy-saving, still can very fast dynamic output character and image function.

 

3, public traffic signal shows a side

 

 

The glow brightness that using LED to hand in those who connect signal lamp to become large dominant position is LED is big, visibility is high, in the late evening when what can look is very clear, look to also go to the lavatory from far.

 

Additionally LED signal lamp can adjust the brightness of itself of LED traffic signal lamp from what move according to the brightness circumstance all round. The largest dominant position of LED traffic signal lamp is energy-saving grow with use time.

 

Additional on one hand, the product of LED signal lamp that works to needing electrify all the year round will tell, LED signal lamp is energy-saving grow with use time. If the incandescent lamp according to the tradition, if incandescent lamp is in,the filament inside burned out, change the word of a signal lamp, the likelihood can form traffic to embrace, come down integratedly quite so, product of LED traffic signal lamp more have an advantage.

 

4, back illuminant shows a field

 

 

As LED technology update ceaselessly, LED product is in be in a poor light the domain also is to have a day. LED product replaces what fluorescent lamp is in charge of to be in a poor light gradually indication action. Because the volume of LED is minorrer, can give off light directly from the back end of face plate liquid crystal directly, and the limits point of view of illuminate is old, promoted the durable degree of monitor and brightness. Be in a poor light as liquid crystal with LED showing is very reasonable so.

 

Illume domain

 

1, indoor illume.

 

 

Indoor illume is told commonly, use illuminant color is Bai Guang. Turn over historical canto, LED begins from 1996, the promotion of the glow efficiency of LED and brightness year after year, with the white brightness on the market is told now, the brightness inside the industry achieved 130 lumen basically every are made of baked clay.

 

As the promotion of LED technology, the price of LED also is in ceaseless fall, so LED more and more the incandescent lamp that replaces a tradition and fluorescent lamp, fashioned the current illume product on market. Be based on this element, the market of LED Bai Guang can be a very big cake.

 

2, indoor decorate illume product.

 

Through 3 base deserve lubriciously to compare, control electric current, LED product can come true a lot of in the commutation of color. Also be this reason, increase the people understanding to LED product. Be in the world of this rich and colorful, people chooses also be rich and colorful to adorn a product, people is in illuminative process, deflection Yu Jiang moves colorific aesthetic feeling. The diversification of color of LED illuminant product promoted the development that LED lamp acts the role of.

 

3, the landscape inside the city decorates illume.

 

 

Landscape illume is told popularly even if decorate illume publicly. Home is certain and municipal project, municipal unit, to promote urban image, often be in illume of this city landscape is thrown this piece with great quantity. On additional explicit north wide deep demonstrative project obtains the landscape illume of these a few big cities good be the firsting action, LED landscape illume more and more get the favour of small town in home.

 

4, car illume.

 

 

Well-known, LED product is had energy-saving, use time is long, the reason with response rapid rate, LED illume product has been in this domain strikes car illume violently. At present LED car gets with the lamp the limitation of relevant attestation, growth of LED light market is slow. But later period, produce ceaseless promotion of the technology as LED, drop ceaselessly with what reach LED price, LED product future can hold whole vehicle use illume field.

 

Travel feeling technology field

 

1, full automatic door sensor

 

LED product has white color not only, the color of visible light, what still have sightless light more is infra-red and ultraviolet. Infra-red product can be used in domain of automatic door induction. LED passes the sensor photograph of feeling product and infra-red semiconductor laser to compare, LED is passed feeling in limits of intensity of illumination more have an advantage.

 

2, form code scanner

 

In common the code reads a form write implement in, LED is close to as illuminant and enlighten object. Form code is read write implement medium sensor reads the data that takes a form yard with the resolution of 0.1mm. LED passes the bar code scanner of feeling technology and traditional semiconductor laser to be compared, the cost that uses LED to pass feeling technology more low, and read extraction space also more close, working efficiency promotes in the meeting on certain level.

 

The domain that print

 

As the development of LED industry, LED technology also is in ceaseless promotion and innovation. LED replaces traditional illuminative to also be in at the same time the product that substitutes other category.

 

Replaced laser to print technical administrative levels for example. The core that laser prints uses the laser parts of an apparatus of semiconductor device make it namely, if semiconductor laser parts of an apparatus is replaced by LED place, so laser is printed also be replaced.

 

Laser is printed still have a corrupt practice, it is the high cost that the scanner makes. Present laser is printed even if undertake scanning with the scanner, if use printer of LED make it, the tall brightness LED that passes strip namely replaces a scanner.

 

Although current condition will tell, LED printer still is in the phase that just started, but the ceaseless maturity as LED technology, breakthrough and development, LED printer later period can make the mainstream product of the market.

 

The article is reprinted from sensor technology.