Patent ID: 7287865

Claim:
A display optical system comprising: a light source; an image display means which receives a light beam emitted from the light source; an illumination unit installed in between the light source and the image display means, the illumination unit comprising: an optical device which outputs the light beam inputted from the light source, a first lens for transmitting the emitted light ray from the optical device and a second lens on which the transmitted light ray from the first lens incidents; a reflection mirror for changing a light path of a light ray, the reflection mirror provided in between the first lens and the second lens; and a projection part for projecting an image formed on the image display means onto a screen, wherein an optical axis of the first lens, the second lens and a projection lens of the projection part are all in parallel, and wherein if a light ray to the optical axis of the first lens is incident on the second lens and emitted by the second lens, an angle between the emitted light ray from the second lens and the optical axis of the first lens is equal to an angle between an emitted light ray from the image display means in an on state and the emitted light ray from the second lens.