1. Technical Field
The present disclosure relates to a lighting apparatus, and in particular to a lighting apparatus for correcting a change in visual performance due to aging.
2. Description of the Related Art
According to the arrival of an aging society, there has been a great demand for a comfortable environment for middle and older aged people. In particular, improvement in visual environment achieved by lighting is an urgent issue. It is thus necessary to clarify how lighting can correct a change in human visual system caused by aging. Examples of a change in visual performance due to aging mainly include (a) a fall in transmittance of a crystalline lens, in particular a fall in transmittance of a crystalline lens in a short wavelength range, and (b) a bleary eye (intraocular scattering) due to a cataract (a crystalline lens clouding over).
In order to address (a), lighting which increases a proportion of blue light that reaches a retina by intensifying light in a wavelength range where a transmittance of a crystalline lens falls, or in other words, by causing light to have a so-called high color temperature is recommended for middle and older aged people, as disclosed in Japanese Unexamined Patent Application Publication No. 2003-237464.
Furthermore, there is a method of intensifying blue light components in order to take also (b) into consideration, as disclosed in Japanese Unexamined Patent Application Publication No. H04-137305. Japanese Unexamined Patent Application Publication No. H04-137305 recommends lighting which reduces glare by mainly reducing light in a wavelength range (of 470 nm to 530 nm inclusive) which has strong influence on glare, and thus yields advantageous effects of allowing users to perceive high contrast, high lightness, and high color saturation.
Taking (b) into consideration, there is also a method of adjusting a color-variable wall in order to reduce intraocular scattering due to ambient light, as disclosed in Japanese Unexamined Patent Application Publication No. 2005-302500.