A β-sialon phosphor that is a solid solution of europium, in which D.sub.50 is 7.0 μm or more and 20.0 μm or less and (D.sub.50−D.sub.10)/D.sub.50 is 0.60 or less, where D.sub.50 is a 50% area diameter of primary particles of the β-sialon phosphor, and D.sub.10 is a 10% area diameter of the primary particles of the β-sialon phosphor. Primary particles are defined as single-crystal particles distinguished for each crystal orientation by identifying the crystal orientation of individual particles of the β-sialon phosphor by an electron backscatter diffraction image method. D.sub.50 and D.sub.10 are obtained by image analysis of the cross-sectional area of the primary particles.

The present invention relates to a white light source and illumination apparatus for limiting wavelength of 450 nm or less and, more particularly, to a white light source and illumination apparatus for lighting in a lithography or other process, capable of realizing white light even with the limited wavelength of 450 nm or less light. Disclosed is a white light illumination apparatus for limiting wavelength of 450 nm or less, the apparatus comprising a white light source comprising: a blue light-emitting diode element having an emission peak wavelength of 450-490 nm; and an encapsulation layer which encapsulates the blue light-emitting diode element, wherein in the encapsulation layer, one or more phosphors which realize white light emission along with the blue light-emitting diode element, and a blocking agent which blocks light of wavelength of 450 nm or less are scattered, thus forming a first peak region at a wavelength of 450-490 nm and a second peak region which realizes white light emission in combination with the first peak region and limiting the wavelength of 450 nm or less.

The present disclosure provides methods for generating tunable white light with controllable circadian energy performance. The methods use a plurality of LED strings to generate light with color points that fall within blue, yellow/green, red, and cyan color ranges, with each LED string being driven with a separately controllable drive current in order to tune the generated light output. Different light emitting modes can be selected that utilize different combinations of the plurality of LED strings in order to tune the generated white light. One or more of the LED strings can have ultraviolet or violet LEDs.

A phosphor powder contains an EU-activated β-type sialon phosphor particles. When a median diameter in the phosphor powder having not been subjected to an ultrasonic homogenizer treatment is set as D1 and a median diameter in the phosphor powder having been subjected to an ultrasonic homogenizer treatment is set as D2, 1.05≤D1/D2≤1.70. A dispersion liquid in which 30 mg of the phosphor powder is uniformly dispersed in 100 ml of a 0.2% concentration of a sodium hexametaphosphate aqueous solution is added to a columnar container of which a bottom surface has an inner diameter of 5.5 cm. Then, the dispersion liquid is irradiated with ultrasonic waves for 3 minutes at a frequency of 19.5 kHz, and an output of 150 W, in a state where a cylindrical tip, which has an outer diameter of 20 mm, of an ultrasonic homogenizer is immersed in the dispersion liquid in ≥1.0 cm.

[Problem] The object of the present invention is to provide a static electricity distribution-visualizing material, a static electricity-visualizing film, a static electricity distribution-visualizing device, and a static electricity distribution-visualizing method, which can visualize a charged state to be seen with naked eyes so as to intuitively understand a static electricity distribution. [Solution] A static electricity distribution-visualizing material is manufactured so as to contain at least one of a fluorescent substance, a luminescent substance, an electroluminescent substance, a fractoluminescent substance, a photochromic substance, an afterglow substance, a photostimulated luminescent substance and a mechanoluminescent substance.

The present disclosure provides methods for generating tunable white light with controllable circadian energy performance. The methods use a plurality of LED strings to generate light with color points that fall within blue, yellow/green, red, and cyan color ranges, with each LED string being driven with a separately controllable drive current in order to tune the generated light output. Different light emitting modes can be selected that utilize different combinations of the plurality of LED strings in order to tune the generated white light. One or more of the LED strings can have ultraviolet or violet LEDs.

Provided a method of producing a β-sialon fluorescent material having excellent emission intensity. The method includes providing a first composition containing aluminum, an oxygen atom, and a europium-containing silicon nitride, heat treating the first composition, contacting the heat-treated composition and a basic substance to obtain a second composition, and contacting the second composition resulting from contacting the heat-treated composition with the basic substance and an acidic liquid medium containing an acidic substance.

A light-emitting device including a solid-state light source that emits light having a peak wavelength in the range of 480 nm or less and a fluorescent film that covers the solid-state light source and includes at least one kind of phosphor, wherein the fluorescent film includes at least one kind of near-infrared phosphor that is excited by light from the solid-state light source, has a peak wavelength in the range exceeding 700 nm, and has an emission spectrum with a full width at half maximum of 100 nm or more in a range including the peak wavelength.

The present invention relates to a white light source and illumination apparatus for limiting wavelength of 450 nm or less and, more particularly, to a white light source and illumination apparatus for lighting in a lithography or other process, capable of realizing white light even with the limited wavelength of 450 nm or less light. Disclosed is a white light illumination apparatus for limiting wavelength of 450 nm or less, the apparatus comprising a white light source comprising: a blue light-emitting diode element having an emission peak wavelength of 450-490 nm; and an encapsulation layer which encapsulates the blue light-emitting diode element, wherein in the encapsulation layer, one or more phosphors which realize white light emission along with the blue light-emitting diode element, and a blocking agent which blocks light of wavelength of 450 nm or less are scattered, thus forming a first peak region at a wavelength of 450-490 nm and a second peak region which realizes white light emission in combination with the first peak region and limiting the wavelength of 450 nm or less.

A phosphor plate including a base material, and a plate-shaped composite including phosphors dispersed in the base material, in which a main component of the base material is alumina, the phosphor includes an α-type sialon phosphor, and L* value satisfies 73.5 or more and 85.0 or less, a* value satisfies 4.4 or more and 8.0 or less, and b* value satisfies 10.8 or more and 13.0 or less in L*a*b* color coordinates of the phosphor plate in a case of being measured in accordance with JIS Z 8781-4.