Image display device and head-mounted display

摘要

A video image display device (1) is provided with an ocular optical system (12) that guides video image light from a display element (11) to the pupil of an observer through an ocular prism (21) and at the same time guides ambient light to the pupil of the observer through the ocular prism (21). The eyepiece optical system (12) has reflection planes set in the ocular prism (21) that are provided with three or more planes to fold down three or more times an optical path for the video image light from the display element (11), wherein an HOE (23) is formed on at least one plane of the reflection planes. The video image display device (1) satisfies a conditional equation that properly prescribes the relationship between an incident range of the video image light incident on the HOE (23) formed plane in the ocular prism (21) and a display screen size of the display element (11). Thus, the video image display device (1) can widely secure both a video image observation area and a see-through area with a small compact structure.