Projection display device in which positions of projection lens unit and projection mirror unit relative to illumination optical systems are switched

1. A projection display device comprising:

an illumination optical system for illuminating modulated light in accordance with a video signal, the illumination optical system including a light source and an imager for modulating light from the light source in accordance with the video signal;

a projection lens unit into which light is entered from the illumination optical system;

a projection mirror unit for reflecting light from the projection lens unit; and

a moving mechanism for moving the projection lens unit and the projection mirror unit relative to the imager, between a first position where an image is projected in a shape that is longer along a direction of projection onto a projection plane and a second position where an image is projected in a shape that is longer along a direction perpendicular to the direction of projection onto a projection plane.

2. The projection display device according to claim 1 , wherein

the moving mechanism includes a holder rotating relative to the illumination optical system and holding the projection lens unit such that a center of an optical axis of the projection lens unit is positioned eccentrically with respect to a center of the rotation thereof.

3. The projection display device according to claim 2 , wherein

the center of the rotation of the holder aligns in an optical manner approximately with a center position of the imager in the illumination optical system, and

assuming that a distance between the center of the rotation of the holder and the center of the optical axis of the projection lens unit is r and that a dimension of a display area of the imager along a long axis is b, a position of the projection lens unit with respect to the holder is set such that r>b/2 is satisfied.

4. The projection display device according to claim 2 , wherein

the holder rotates relative to the illumination optical system, between a first rotation position where an optical axis plane containing the center of the optical axis of the projection lens unit and the central axis of light projected from the projection mirror unit is approximately perpendicular to an optical element placement plane of the illumination optical system and a second rotation position where the optical axis plane is approximately parallel to the optical element placement plane, and

assuming that the illumination optical system is divided into first and second areas by the optical axis plane when the holder is in the first rotation position, light from the projection lens unit when the holder is in the second rotation position travels toward, out of the first and second areas, either one that is smaller in dimension along a direction perpendicular to the optical axis plane.

5. The projection display device according to claim 4 , wherein

the imager in the illumination optical system is placed such that a surface along a short axis thereof is positioned on the optical element placement plane.

6. The projection display device according to claim 1 , comprising:

a sensor for detecting whether relative positions of the projection lens unit and the mirror unit are in the first position or the second position; and

an image processing part for switching a video signal processing mode based on a result of detection by the sensor.

7. The projection display device according to claim 1 , comprising:

a screen holding mechanism that can be attached to and detached from a screen.