Patent ID: 7744226

Claim:
A projection image display apparatus comprising: an illumination optical system configured to generate an illumination light; a projection optical system configured to project an image light onto a screen; a reflective image forming device configured to modulate the illumination light so as to form the image light, the reflective image forming device having an image forming surface on which a plurality of micromirrors are arranged two-dimensionally, a rotational angle of the micromirrors being set to at least one of first and second angles according to a picture signal input into the reflective image forming device, the micromirrors being configured to reflect the illumination light in a first direction where the light is led to the screen via the projection optical system at the first angle and to reflect the illumination light in a second direction where the light is not led to the screen at the second angle; a reflection mirror arranged in a position opposite to an optical path of the illumination light to enter the reflective image forming device across an optical path of the image light reflected in the first direction by the micromirrors at the first angle, the reflection mirror configured to reflect the light reflected in the second direction by the micromirrors at the second angle in a direction separated from the image light; a sealed structure that seals the image forming surface of the reflective image forming device and the reflection mirror; and a transparent member that comprises a part of the sealed structure, is arranged in a position opposed to the reflection mirror, and is configured to transmit the light reflected by the reflection mirror to an outside of the sealed structure, wherein: the illumination optical system is arranged so as to emit the illumination light to the image forming surface of the reflective image forming device from below, the image forming surface of the reflective image forming device has a rectangular shape having a long side and short side, a rotational axis of the micromirrors is parallel with the long side of the image forming surface, and the light beams reflected to the first and the second directions by the micromirrors set at the first and the second angles are led upward, and the projection optical system has a plurality of curved mirrors that lead the image light from the reflective image forming device to the screen in a down-to-up direction.