| 摘要 |
PROBLEM TO BE SOLVED: To prevent generation of a reception error in a target when the target moving within or out of a sweep range of a transmitted optical signal moves at a speed not more than a preset speed. SOLUTION: A light projector 3 sweeps the range of a sweep distance L and irradiates the target range with the optical signal. Accordingly, even if the target 8 moves outside the target range in an arrow direction, the target 8 can be certainly received. When an object 9 outside the target range moves into the target range after switch operation, the optical signal of the light projector 3 does not receive the object 9 because the light projector 3 has already moved to the sweep direction of the arrow. When the light projector 3 sweeps in a time not less than [L/ä((S-AD)/2D)-A}], the target 8 can be certainly received when the target 8 within the target range moves at a speed not more than a maximum movement speed A (wherein, D is a reception time of one data length). COPYRIGHT: (C)2004,JPO
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