| 摘要 |
PROBLEM TO BE SOLVED: To provide a technique capable of preventing temperature rise of a light receiving element due to constant irradiation with light. SOLUTION: A light projection device 1 includes: an infrared semiconductor laser emitting laser light; an optical transmission path transmitting the incident laser light; an optical element disposed between the infrared semiconductor laser and the optical transmission path and condensing the laser light toward the optical transmission path; a displacement means for moving the optical element to displace the condensing position of the laser light; an optical scanning means LS for displaying an image corresponding to an image signal on a projection surface by periodically performing scanning with the emission light from the optical transmission path; the light receiving element PD1 intermittently receiving the emission light subjected to scanning by the optical scanning means LS; and a control part CN for controlling the displacement means according to an output signal of the light receiving element PD1 and guiding the condensing position of the laser light to an incident port of the optical transmission path. Because the light receiving element PD1 thereby intermittently receives the emission light, the temperature rise of the light receiving element due to the constant irradiation with light is prevented. COPYRIGHT: (C)2009,JPO&INPIT
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