| 摘要 |
PURPOSE:To correct distortion of a projected image by employing a part which generates signal along an optical axis of a projecting lens, a part which receives the signal, and an adjusting part which moves the projecting lens and a projecting object in relation to each other. CONSTITUTION:When a point P on an original 7 is projected onto a screen 14, a light emitting means 16 projects infrared ray to a point P2 on the screen by command of a processor 37; a position detecting means 21 receives reflected light; and then photoelectric currents I1 and I2 are obtained from electrodes 21d and 21e, respectively, based on the center of gravity of incident light LP. Information on the position of incident spot light LP is given to the processor 37 via amplifiers 32 and 33, an analog switch 35, and an A/D converter 36. The processor 37 calculates the degree of deviation from a focal point and rotates a motor 39 by a prescribed quantity so that the lens 10 moves along the optical axis, thereby adjusting the focal point. When a projection center is transferred to B, an expanding and contracting part 4c is extended by a prescribed length R. Thus, the point P is transferred to the projection center B, and the image, having the point B as its center, is free from a trapezoid distortion. |
