LIGHT EMITTING DEVICE WITH BA2MGSI2O7:EU2amp;plus;, BA2SIO4:EU2amp;plus;, OR (SRXCAY BA1-X-Y)(A1ZGA1-Z)2SR:EU2amp;plus;PHOSPHORS

摘要

A lamp comprises a light emitting element such as a light emitting diode or a laser diode which emits blue light, and a phosphor composition which absorbs the blue light having a first spectrum from the light emitting element and emits light having a second spectrum. The phosphor composition comprises at least one of Ba₂MgSi₂O₇:Eu_2+; Ba₂SiO₄:Eu^2+; and (Sr,Ca,Ba)(Al,Ga)₂S₄:Eu^2+. The invention also relates to a light emitting element which emits blue light, and a phosphor composition which absorbs the blue light from the light emitting element having a first spectrum and emits light having a second spectrum, wherein the spectral luminous efficacy of light emitted by the lamp is at least 550 lumens per watt. The high spectral luminous efficacy of the output spectrum efficiently converts the power input to the lamp into lumens to provide a high brightness. For example the device luminous efficacy of the lamp can be 35-45 lumens output per watt of input electric power or more.