A light source for myopia prevention article includes a light emitter to emit light having an emission spectrum continuing from a first wavelength of not less than 360 nm nor more than 400 nm to a second wavelength of more than 400 nm.

A marker for illuminating an area of an aircraft, the marker including a photoluminescent material arranged to emit blue visible light in response to an excitation and wherein the photoluminescent material has an emission spectrum with a maximum peak intensity of from 450 nm to 510 nm and optionally substantially 490 nm. The photoluminescent material has a performance characteristic such that the emissivity is at least 0.3 mcd/m.sup.2 12 hours after cessation of charging at 25 lux for 45 mins optionally at least 30 mcd/m.sup.2 6 hours after cessation of charging. The photoluminescent material comprises at least a main pigment containing a Europium and Dysprosium doped strontium aluminate with the formula Sr.sub.4Al.sub.14O.sub.25:Eu,Dy and optionally one or more further phosphorescent pigments. A marker system is disclosed for illuminating areas of an aircraft, the system including a plurality of markers in accordance with the invention. Also disclosed is an aircraft including a passenger cabin; and a marker system as disclosed.

This invention provides an orange-yellow-emitting phosphor, the preparation method and the use thereof. This orange-yellow-emitting phosphor has a general formula represented by formula I: Sr.sub.9?a?b?xM.sub.aMg.sub.1.5+b(PO.sub.4).sub.7:xEu.sup.2+ formula I; wherein in formula I, said M is one or two of Ca and Ba; and 0.001?x?0.9, 0?a?1.0, 0?b?2.3. This orange-yellow-emitting phosphor uses a phosphate as the host material and Eu.sup.2+ ions as activation ions. The chemical properties of the phosphor are stable. The phosphor has relatively wide excitation band and emission band. And the red component in its emission spectrum is abundant, therefore, coupling the blue InGaN chip with the orange-yellow-emitting phosphor provided by this invention can obtain warm white light. The phosphor is radiation free, therefore, it will not be harmful to the environment. It is indicated by experimental results that this orange-yellow-emitting phosphor can be effectively excited by light at a wavelength of 250-500 nm and emits a wide peak at 470-850 nm, wherein the main emission peaks lie at about 523 nm and 620 nm. This preparation method is simple, and the cost is relatively low, so it is amenable to industrial production.

A lighting apparatus for emitting white light including a semiconductor light source emitting radiation with a peak emission between from about 250 nm to about 500 nm and a first phosphor having a peak emission between about 550 and 615 nm, wherein an overall emission spectrum of the lighting apparatus has a depression between about 550 and 615 nm, whereby the red-green color contrast is increased versus a reference illuminant.

Green-emitting phosphors are useful in devices including an LED light source radiationally coupled and/or optically coupled to the phosphors, which are selected from [Ba.sub.1abSr.sub.aCa.sub.b].sub.x[Mg,Zn].sub.y(UO.sub.2).sub.z([P,V]O.sub.4).sub.2(x+y+z)/3, where 0a1, 0b1, 0.75x1.25, 0.75y1.25, 0.75z1.25; and [Ba,Sr,Ca,Mg,Zn].sub.p(UO.sub.2).sub.q[P,V].sub.rO.sub.(2p+2q+5r)/2, where 2.5p3.5, 1.75q2.25, 3.5r4.5.

The present invention provides a light emitting device comprising a first light emitting portion that emits white light at a color temperature of 6000K or more and a second light emitting portion that emits white light at a color temperature of 3000K or less, which include light emitting diode chips and phosphors and are independently driven. The present invention has an advantage in that a light emitting device can be diversely applied in a desired atmosphere and use by realizing white light with different light spectrums and color temperatures. Particularly, the present invention has the effect on health by adjusting the wavelength of light or the color temperature according to the circadian rhythm of humans.

An LED light emitting device is provided that has high color rendering properties and is excellent color uniformity and, at the same time, can realize even luminescence unattainable by conventional techniques. A phosphor having a composition represented by formula: (Sr.sub.2-X-Y-Z-Ba.sub.XMg.sub.YMn.sub.ZEu.sub.)SiO.sub.4 wherein x, y, z, and are respectively coefficients satisfying 0.1<x<1, 0<y<0.5, 0<z<0.1, y>z, and 0.01<<0.2 is provided. The phosphor is used in combination with ultraviolet and blue light emitting diodes having a luminescence peak wavelength of 360 to 470 nm to form an LED light emitting device.

The present invention provides a light emitting device comprising a first light emitting portion that emits white light at a color temperature of 6000K or more and a second light emitting portion that emits white light at a color temperature of 3000K or less, which include light emitting diode chips and phosphors and are independently driven. The present invention has an advantage in that a light emitting device can be diversely applied in a desired atmosphere and use by realizing white light with different light spectrums and color temperatures. Particularly, the present invention has the effect on health by adjusting the wavelength of light or the color temperature according to the circadian rhythm of humans.

Green-emitting phosphors are useful in devices including an LED light source radiationally coupled and/or optically coupled to the phosphors, which are selected from [Ba.sub.1-a-bSr.sub.aCab].sub.x[Mg,Zn].sub.y(UO.sub.2).sub.z[P,V]O.sub.4).sub.2(x+y+z)/3, where 0a1, 0b1, 0.75x1.25, 0.75y1.25, 0.75z1.25; and [Ba,Sr,Ca,Mg,Zn].sub.p(UO.sub.2).sub.q[P,V].sub.rO.sub.(2p+2q+5r)/2, where 2.5p3.5, 1.75q2.25, 3.5r4.5.

An inventive luminescent material suitable for use as a phosphor for an LED includes a nitridophosphate material having a general formula AE.sub.y-xLi.sub.10-2yP.sub.4N.sub.10:Eu.sub.x, wherein (i) AE includes one or more of Ca, Sr, or Ba, and (ii) yx>0. In some instances, y can equal 2 and x can be between 0 and 0.1. In some instances, AE can include only Ca; in some other instances, AE can include a majority amount of Ca and lesser amounts of Sr or Ba. In some instances, the luminescent material can exhibit a peak emission wavelength greater than 600 nm.