Image display apparatus including a first and second prism array

Abstract

An image display apparatus, e.g., a head-mounted image display apparatus, which uses a compact optical system and yet has minimal aberrations and a large exit pupil diameter. An image displayed on a liquid crystal display device (2) is projected as an enlarged image in a user's eyeball by a convex lens (3). Prism arrays (13 and 14) having the same vertex angle are disposed in parallel to each other between the convex lens (3) and an exit pupil (6) so that the array directions coincide with each other. A parallel beam of light passed through the convex lens (3) has a pupil diameter (a) determined by the numerical aperture of an illumination system (1). The parallel beam first enters the prism array (13) and separates into light beams traveling in four different directions by the prism refracting action. These light beams then enter the prism array (14), which has the same vertex angle as that of the prism array (13). Consequently, the light beams are refracted again to become parallel to each other. As a result, the beam diameter (a) of the light before entering the prism array (13) enlarges to a beam diameter (b) after the light has emanated from the prism array (14). Accordingly, the effective pupil diameter enlarges.

Dependencies are inferred from the claim text.