Patent ID: 8976453
Filing Date: 2015-03-10
Classification: G02B

Abstract:
1. An image display device comprising: (A) an image generating device; (B) a light guide unit in which light from the image generating device is incident thereon, is guided therein, and then emitted toward the pupil of an observer and which includes (B-1) a light guide plate in which incident light is propagated by total reflection in the inside and then emitted therefrom, (B-2) a first deflection section which is disposed at the light guide plate and deflects light incident on the light guide plate such that the light incident on the light guide plate is totally reflected in the inside of the light guide plate, and (B-3) a second deflection section which is disposed at the light guide plate and deflects the light propagated by total reflection in the inside of the light guide plate over multiple times so as to make the light propagated by total reflection in the inside of the light guide plate be emitted from the light guide plate; and (C) a light beam extension device which extends a light beam incident from the image generating device, along a Z direction when an incident direction of light which is incident on the light guide plate is set to be an X direction and a direction of propagation of light in the light guide plate is set to be a Y direction, and then emits the light beam to the light guide unit, wherein the light beam extension device includes a first reflecting mirror on which light from the image generating device is incident, and a second reflecting mirror on which light from the first reflecting mirror is incident and which emits the light to the light guide unit, a light reflecting surface of the first reflecting mirror has a first A slope and a first B slope which are continuously juxtaposed alternately, and a sawtooth-shaped cross-sectional shape, the top and the base of the first A slope are parallel and extend in the Z direction, in a pair of a first A slope and first B slope, an angle formed by the bottom of the first A slope and the bottom of the first B slope is 90 degrees and the length of the first A slope is shorter than the length of the first B slope, the height of the first A slope is constant, when an incidence angle of light on the first reflecting mirror is set to be η a light reflecting surface of the second reflecting mirror has a second A slope and a second B slope which are continuously juxtaposed alternately, and a sawtooth-shaped cross-sectional shape, the top and the base of the second A slope are parallel and extend in the Y direction, in a pair of a second A slope and second B slope, an angle formed by the bottom of the second A slope and the bottom of the second B slope is 90 degrees and the length of the second A slope is shorter than the length of the second B slope, the height of the second A slope is constant, and when an incidence angle of light on the second reflecting mirror is set to be η