Photocatalyst, light source and lighting device

A light source including:

• an airtight container formed of a translucent material that transmits at least rays of light having wavelengths of not more than 410 nm;
• a photocatalytic film which is so formed on at least a part of the outer surface of said airtight container as to not generate interference between visible light and transmitting light such that transmittance of the photocatalytic film of visible light at a wavelength of 550 nm is at least 15% higher than the transmittance of ultraviolet light having a wavelength of 365 nm;
• and
• a light emission means disposed in the airtight container.

A lighting device including:

• a main body which incorporates a light source and a radiation opening, said light source emitting at least rays of light having wavelengths of not more than 410 nm;
• a base member disposed at the radiation opening of the main body and transmitting visible light as well as rays of light having wavelengths of not more than 410 nm;
• and
• a photocatalytic film which is so formed on either a part of or the entire surface of at least a surface of the base member so as to not generate interference between visible light and transmitting light such that the transmittance of the photocatalytic film of visible light at a wavelength of 550 nm is at least 15% higher than the transmittance of ultraviolet light having a wavelength of 365 nm.

A lighting device including:

• a main body incorporating a light source emitting ultraviolet light in the wavelength range of 300 nm to 410 nm at not less than 0.05 W per 1000 lm of visible light;
• a translucent cover disposed in the main body in such a state as to cover the light source, said translucent cover having transmittance not less than 80% for at least a part of ultraviolet light in the wavelength range of 300 nm to 410 nm;
• and
• photocatalytic films which contain titanium oxide as the main component and formed on both sides of the translucent cover.