| 摘要 |
PROBLEM TO BE SOLVED: To provide a vehicle existence informing device 1 which announces the existence of a vehicle with a warning sound without using a large-capacity loudspeaker. SOLUTION: In the vehicle existence informing device 1, each of loudspeakers 2 to 4 constituting a loudspeaker array 5 emits the warning sound to air as an ultrasonic wave, and a microcomputer 6 outputs a command for switching between a positive terminal and a negative terminal of the loudspeaker 3, to a relay box 7 at predetermined time intervals. Therefore, oscillation of an oscillator of the loudspeaker 3 repeats a state of having a phase that matches phases of oscillation of oscillators of loudspeakers 2 and 4 and a state of having a phase delayed relative to them by 180°. Thus, the warning sound having high directivity is emitted in a plurality of direction to announce the existence of a vehicle without using the loudspeaker having large capacity. COPYRIGHT: (C)2011,JPO&INPIT
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