| 摘要 |
PROBLEM TO BE SOLVED: To find a range without being affected by regular reflected light from an image projection surface in measuring a distance from a projector to the image projection surface by an active range finder and performing the focusing of a projection lens. SOLUTION: An image displayed on a liquid crystal panel 27 is projected on the image projecting surface 9 through the projection lens 21. The optical axis 21a of the projection lens 21 is vertical to the image projecting surface 9, then, the optical axis 24a of the range finding light 24a is inclined to the optical axis 21a of the projection lens 21 so that the optical axis 24a may not be vertical to the image projecting surface 9. Even if a material having a high reflectance such as a white board is used as the image projection surface 9, the regular reflected light from the surface is hardly made incident on the light receiving element of the range finder, then, the range finding accuracy is enhanced. It is allowed to incline the optical axis 24a of the projecting light in either direction, but, it is preferable that the axis may be inclined in a direction coming close to the center of the projected image, and it is preferable that the inclination angle is within an extent of 2.5°to 20°. COPYRIGHT: (C)2005,JPO&NCIPI |
