Nichia Corporation

Atsushi Yoshinari

Shoji Hosokawa

Kazuya Nishimata

Makiko Iwasa

Yasuaki Mashima

Masato Okawa

A light emitting device includes a light emitting element having a dominant wavelength in a range of 400 nm or more and 500 nm or less, and a wavelength conversion member that is arranged on a light emitting side of the light emitting element and includes a rare earth aluminate fluorescent material having a composition represented by the following formula (I), wherein the light emitting device emits light having a dominant wavelength in a range of 475 nm or more and 500 nm or less, and wherein the light emitting device emits light having an S/P ratio of 6.5 or less derived from the formula (1), which is the ratio of a luminous flux in scotopic vision relative to a luminous flux in photopic vision:(LuLnCe)(AlGa)O&#x2003;&#x2003;(I)

Light emitting device emitting light bright in both scotopic vision and photipic vision

A method for producing a rare earth aluminate fluorescent material, including: preparing, as raw materials, cerium oxide having a crystallite diameter in a range of 200 &#x212b; or more and 1,600 &#x212b; or less, a compound containing at least one kind of a rare earth element Ln selected from the group consisting of Y, La, Lu, Gd, and Tb, a compound containing Al, and depending on necessity a compound containing at least one kind of an element M1 selected from the group consisting of Ga and Sc, wherein a total molar ratio of the rare earth element Ln and cerium is 3, a total molar ratio of Al and the element M1 is a product of a parameter k in a range of 0.95 or more and 1.05 or less and 5, a molar ratio of cerium is a product of a parameter n in a range of 0.005 or more and 0.050 or less and 3, and a molar ratio of the element M1 is a product of a parameter m in a range of 0 or more and 0.02 or less, the parameter k, and 5; and subjecting a mixture of the raw materials to a heat treatment to provide a calcined product.

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Tokushima, Japan

Atsushi Yoshinari