Patent ID: 8035759

Claim:
A polarization conversion device comprising: a prism sheet that includes a plurality of long and narrow prism rods each of which has an incidence surface, an emission surface, wherein the incidence surface and the emission surface each other in parallel, a first side surface continued to the incident surface at an inside angle of 45°, and a second side surface continued to the emission surface at an inside angle of 45°, wherein the first side surfaces and the second side surfaces are sequentially bonded to each other so that the plurality of prism rods are arranged in parallel; and retardation films that have optical anisotropy and that are formed of dielectric multilayers being formed on either the first or second side surfaces of the prism rods bonded to each other so that normal lines of the first or second side surfaces substantially match optical axes of the retardation films, wherein bonding borderlines between the plurality of prism rods are inclined by 45° with respect to a polarization direction of linearly polarized light within a plane perpendicular to an incident optical axis of the linearly polarized light, and the bonding borderlines are exposed on the incidence surface or emission surface side.