| 摘要 |
PROBLEM TO BE SOLVED: To achieve the automatic focusing of a projector by a new method different from the conventional one. SOLUTION: In the projector 2 projecting image light to a screen 1 at a fixed divergent angle, detecting light and detecting sound outputted simultaneously from an electronic pen 3 pointing a projection point X projected to the screen 1 are received by a sensor part 25, and the length of a 1st line L1 linking the sensor part 25 and the projection point X in the shortest distance is obtained based on a time difference in a period from receiving the detecting light until receiving the detecting sound, and the length of a 2nd line L2 linking the sensor part 25 and the screen 1 in the shortest distance is obtained by multiplying the length of the 1st line L1 by a predetermined constant, whereby a projection optical system is focused based on the length of the 2nd line L2. COPYRIGHT: (C)2005,JPO&NCIPI
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