To obtain a light source for raising plants, having high efficiency and high reliability by covering both absorption peaks of chlorophyll with one LED.
Firstly, a first luminous layer forming light rays at 400-480 nm wavelength and a second luminous layer for forming light rays at 650-700 nm wavelength in one LED. Secondly, a leak at a short wavelength side (400-480 nm) is formed by a LED main body and a peak at a long-wavelength side (650-700 nm) is formed by a substrate placing the LED. A fluorescent substance for absorbing light rays (400-480 nm) formed by the LED main body and forming light rays at 650-700 nm is used as the substrate. For example, such a fluorescent substrate can be obtained by adding chromium or titanium to sapphire which has been conventionally used as a substrate for a semiconductor light emitting diode. Thirdly, similarly a peak at a short wavelength side is formed by the LED main body and a peak at a long-wavelength side is produced by a fluorescent substance covering the LED main body. Sapphire to which chromium or titanium added is similarly used as the fluorescent substance.
FUJITA SHIGEO
SHIMADA JUNICHI
