A liquid-crystal display device has a transmission type liquid-crystal display
panel including a liquid-crystal cell, the liquid-crystal cell having a back-side
substrate, a visual-side substrate, and a liquid crystal, the back-side substrate
having a transparent substrate, a transparent layer lower in refractive index than
the transparent substrate, and a transparent electrode, the visual-side substrate
having a transparent substrate, and a transparent electrode. The liquid crystal
is held between the back-side and visual-side substrates so that respective electrode
sides of the back-side and visual-side substrates are disposed opposite to each
other, at least one light sources is disposed on one of side surfaces of the transmission
type liquid-crystal display panel, and an optical path control layer has a repetitive
structure of optical path changing slopes on an outer side of the back-side substrate
and is higher in refractive index than the low-refractive-index transparent layer,
and each of the optical path changing slopes is inclined at an inclination angle
in a range of from 35 to 48 degrees with respect to a reference plane of the back-side substrate.