Nakamura and other people which from Nichia company put the Blue ray led synthesized with yellow phosphor white LED for the first time. He used by the yellow phosphor for Y3Al5O12: Ce3 + (hereinafter referred to as YAG: Ce3 +), the phosphor in 470 nm band near a strong broadband absorbed, and then inspire 540 nm nearby yellow light, led itself of the launch of blue and yellow phosphor inspired form with white light. Later, YAG: Ce3 + for its conversion efficiency, high thermal stability and stimulate the band width and so on advantage, become the mainstream of white light technology.

Trend 1: new phosphors development

YAG: Ce3 + is the earliest are widely used in white LED technology of a phosphor, but because the emission spectrum of less red composition, it is difficult to get high and low colour developing index of color temperature white LED; On the other hand, the sustainable development of semiconductor lighting push people develop higher fluorescent the efficiency of conversion. Early, through the in YAG: Ce3 + add (Ca, Sr) S: Eu2 +, (Ca, Sr) Ga2S4: Eu2 + red phosphor to achieve high green colour developing index, low colour temperature requirements, Zinc oxide but because this kind of alkaline metal sulfide chemical and physical properties not stable, easy deliquescence, volatile and corrosive, can not meet the needs of LED lighting industry. Recently, people have developed a thermal stability and chemical stability excellent red phosphors, can replace completely realize high alkaline metal sulfide colour developing index, low colour temperature white LED, because of its silicon nitrogen (oxygen) tetrahedron structure, is called the nitrogen oxides, and has higher inspire efficiency.

At present, foreign companies with phosphor aspects in LED technology is mature, Titanium dioxide and hold most of the important patents. They through phosphor patent to the holding of the occupation and LED the market, YAG: Ce3 + phosphors mainly by Nichia patent occupies [U.S. 5998925], Osram is occupied Tb3Al5O12: Ce3 + phosphor patent [U.S. 6812500, 6060861652693,], TG, LWB and Tridonic hold Eu2 mixed + (SrBaCa) 2 SiO4Si: Al, B, P, Ge patent [U.S. 6809347], Intematix hold Eu2 mixed + (SrBaMg) 2 SiO4O: F, Cl, N, S patent [U.S. 20060027781, 200627785200281 22]. In domestic, LED the research with phosphors mostly in scientific research institutions, is mainly to the existing phosphor materials synthesis and the content such as the study of light, and the development of the industrialization technology of not doing enough.

Trend 2: white LED optical model and development

Phosphor used in white LED, still need according to the specific needs of LED and decide, Magnesia such as phosphor particle size, etc. Phosphor on research focuses on the optical properties of the phosphor white led to influence on the performance of the package, such as take light efficiency, color space distribution and light color quality above. In these studies, using the monte carlo method of light after mark by optical software simulation LED seal structure optical performance, will be treated to a phosphor layer Mie scattering material that will be through the optical simulation for the white LED to inspire and emission characteristics, but without considering the phosphor simulation specific scattering properties, lack of experiment.

Trend 3: new phosphor coating way

The traditional phosphor coating way for some powder mode, Nickel oxide namely the phosphor and colloid filling the mixture to chip stents cup bowl, then heat cure. This coating way of phosphor is difficult to control, and as a result of light everywhere stimulate different, make the white LED prone to macular or blue light color spot of uneven phenomenon. PhilipsLumileds the company put forward the form coating phosphor coating way, they LED chips in the inversion covered a layer thickness consistent phosphor coating, improve the white LED light color stability. There are also firms in the chip surface deposits a layer of phosphor way to implement motivated. These coating method all is will chip and phosphor contact. H.L uo researchers such as optical simulation results show that the phosphor and chip of the contact near field inspire method, increased the stimulate the light back scattering loss, reduce the device of take light efficiency. Australia's Sommer the numerical simulation method to simulate PhilipsLumileds shape preserving a phosphor coating structure, the results show that the coating method and can't provide better Angle uniformity. With the deepening of the white LED optical simulation, phosphor far field of showed more inspired the superiority of the scheme.

Trend four: big inject current and heat dissipation structure

In order to meet the needs of the general lighting highlights flux, and the people improve the single chip drive power, past the 1 W high power chip is injected into the 3 W, 5 W, or even higher. This makes the white LED ReWenTi more and more serious, people USES all sorts of cooling technology, such as heat pipe, heat pipe, water cooling, cooling the methods, such as heat LED implementation.