LIGHT EMITTING DEVICE

• Main Authors: MITSUISHI IWAO, NUNOGAMI SHINYA, OKADA AOI, FUKUDA YUMI, ISHIDA KUNIO, KATO MASAHIRO, MATSUDA NAOHISA, ARUBESAARU KEIKO
• Format: Patent
• Language: English
• Published: 19.04.2012
• Subjects: ADHESIVES; BASIC ELECTRIC ELEMENTS; CHEMISTRY; DYES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FORELSEWHERE; METALLURGY; MISCELLANEOUS APPLICATIONS OF MATERIALS; MISCELLANEOUS COMPOSITIONS; NATURAL RESINS; PAINTS; POLISHES; SEMICONDUCTOR DEVICES

PROBLEM TO BE SOLVED: To provide a light emitting device that achieves excellent luminous efficacy by suppressing reabsorption between phosphors.SOLUTION: The light emitting device 10 includes: a light emitting element 14 mounted on a board 12; a red phosphor layer 20 which is formed on the light emitting element, has a semicircular shape with a diameter r, and contains a red phosphor represented by the following formula (1) (MEu)SiAlON, wherein M is an element selected from IA group elements, IIA group elements, IIIA group elements, IIIB group elements except Al, rare-earth elements, and IVB group elements; and x1, a, b, c, and d is 0<x1<1, 0.55<a<0.95, 2.0<b<3.9, 0<c<0.6, and 4<d<5.7; an intermediate transparent layer 22 of a transparent resin which is formed on the red phosphor layer and has a semicircular shape with a diameter d; and a green phosphor layer 24 which is formed on the intermediate transparent layer, has a semicircular shape, and contains a green phosphor. The relation between the diameter r and the diameter d satisfies the following equation (2) 2.0r(μm)≤d≤(r+1000)(μm).