A display device includes a display panel, a lighting device, at least one light source, a lighting controller, a complex fluoride red phosphor, and a nitride red phosphor. The one light source includes a blue light emitting element and a red phosphor configured to emit red light when excited by the blue light from the blue light emitting element. The lighting controller is configured to control driving of the light source in synchronization with the image display by the display panel so that a one-frame display period in the display panel includes a turn-on period and a turn-off period. The complex fluoride red phosphor constitutes the red phosphor and has a content ratio in a range from 50% to 85% inclusive. The nitride red phosphor constitutes the red phosphor and has a content ratio in a range from 15% to 50% inclusive.

Embodiments of the invention include a light source and a wavelength converting structure disposed in a path of light emitted by the light source. The wavelength converting structure includes a first phosphor that emits infrared light and a second phosphor that emits visible light. In some embodiments, the light source emits first light, the second phosphor absorbs the first light and emits second light, and the first phosphor absorbs the first light and emits third light and absorbs the second light and emits fourth light.

A material represented by the following formula (I)

(M).sub.8M.sub.6M.sub.6O.sub.24(X,S).sub.2:Mformula (I).

Also disclosed is an ultraviolet radiation sensing material, an X-radiation sensing material, a device and a method for determining the intensity of ultraviolet radiation.

A display device includes a display panel, a lighting device, at least one light source, a lighting controller, a complex fluoride red phosphor, and a nitride red phosphor. The one light source includes a blue light emitting element and a red phosphor configured to emit red light when excited by the blue light from the blue light emitting element. The lighting controller is configured to control driving of the light source in synchronization with the image display by the display panel so that a one-frame display period in the display panel includes a turn-on period and a turn-off period. The complex fluoride red phosphor constitutes the red phosphor and has a content ratio in a range from 50% to 85% inclusive. The nitride red phosphor constitutes the red phosphor and has a content ratio in a range from 15% to 50% inclusive.

A method for producing a -AlON fluorescent material, comprising: preparing a first mixture containing a compound containing Mn, a compound containing Li, a compound containing Mg, an aluminum oxide, and an aluminum nitride, in which the amount of fluorine is 150 ppm by mass or less relative to the total amount of the first mixture excluding fluorine, and subjecting the first mixture to a first heat treatment to obtain a first calcined product having an average particle diameter D1, as measured according to a Fisher Sub-Sieve Sizer method, of 10.0 m or more; and preparing a second mixture containing the first calcined product, a compound containing Mn, a compound containing Li, a compound containing Mg, an aluminum oxide, and an aluminum nitride, in which the amount of fluorine is 150 ppm by mass or less relative to the total amount of the second mixture excluding fluorine, and subjecting the second mixture to a second heat treatment to obtain a second calcined product having an average particle diameter D2, as measured according to the Fisher Sub-Sieve Sizer method, of 16.0 m or more, wherein the second mixture contains the first calcined product in an amount of more than 20% by mass and 82% by mass or less.

Provided is a red light emitting phosphor having a high luminance. The fluoride phosphor has a first composition which includes an alkali metal containing K, Si, Al, Mn, and F. In the first composition, when a total number of moles of the alkali metal is 2: a total number of moles of Si, Al, and Mn is 0.9 to or more and 1.1 or less; a number of moles of Al is more than 0 but and 0.1 or less; a number of moles of Mn is more than 0 but and 0.2 or less; and the a number of moles of F is 5.9 to 6.1. The fluoride phosphor has a crystal structure of cubic system, and a lattice constant of not less than 0.8138 nm.

Synthesizing a color stable Mn.sup.4+ doped phosphor by contacting a gaseous fluorine-containing oxidizing agent with a precursor of: A.sub.aB.sub.bC.sub.cD.sub.dX.sub.x:Mn.sup.4+; A.sub.aiB.sub.biC.sub.ciD.sub.dX.sub.xY.sub.d:Mn.sup.4+; A.sup.1.sub.3G.sub.2?m?nMn.sub.mMg.sub.nLi.sub.3F.sub.12O.sub.p; or AZF.sub.4:Mn.sup.4+. Where A is Li, Na, K, Rb, Cs, or a combination; B is Be, Mg, Ca, Sr, Ba, or a combination; C is Sc, Y, B, Al, Ga, In, Tl, or a combination; D is Ti, Zr, Hf, Rf, Si, Ge, Sn, Pb, or a combination; X is F or a combination of F and one of Br, Cl, and I; Y is O, or a combination of O and one of S and Se; A.sup.1 is Na or K, or a combination; G is Al, B, Sc, Fe, Cr, Ti, In, or a combination; Z is La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, Y, In, or a combination.

Provided are a light-emitting instrument, and an image display device utilizing an AlON phosphor and having wide color gamut. The light-emitting instrument includes an emission source emitting light having a wavelength from 410 nm to 470 nm and a phosphor or a light-transmitting body where the phosphor is dispersed, and the phosphor includes an inorganic compound where an AlON crystal, an AlON solid solution crystal, or an inorganic crystal having a crystal structure identical to AlON includes at least Mn, an A element(a monovalent metal element) it necessary, a D element (a divalent metal element) if necessary, an E element (a monovalent anion) if necessary, and a G element (one or more elements other than Mn, the A, Al, O, N, the D, or the E) if necessary, and emits fluorescence having a peak wavelength from 515 nm to 541 nm upon irradiation of an excitation source.

The invention provides a light emitting diode device comprising a light emitting diode arranged on a substrate and a wavelength converting element. The wavelength converting element contains as a luminescent material a Mn.sup.4+-activated fluoride compound having a garnet-type crystal structure. The Mn.sup.4+-activated fluoride compound preferably answers the general formula {A.sub.3}[B.sub.2-x-yMn.sub.xMg.sub.y](Li.sub.3)F.sub.12-dO.sub.d, in which formula A stands for at least one element selected from the series consisting of Na.sup.+ and K.sup.+ and B stands for at least one element selected from the series consisting of Al.sup.3+, B.sup.3+, Sc.sup.3+, Fe.sup.3+, Cr.sup.3+, Ti.sup.4+ and In.sup.3+, and in which formula x ranges between 0.02 and 0.2, y ranges between 0.0 (and incl. 0.0) and 0.4 and d ranges between 0 (and incl. 0) and 1. Said compound is most preferably {Na.sub.3}[Al.sub.2-x-yMn.sub.xMg.sub.y](Li.sub.3)F.sub.12-dO.sub.d.

An optical member includes a first light guide member having an elongated shape and comprising an end surface and a lateral surface extending in a longitudinal direction from the end surface; and a wavelength conversion layer disposed on the lateral surface of the first light guide member and containing a phosphor.