| 摘要 |
Provided is a sound wave sensor that can reliably detect the presence/absence of paper money very easily by employing sound waves. This sound wave sensor comprises: a sound generating body (2) that outputs a sound wave signal having a predetermined frequency; an echo body (3) that is provided in opposition to the direction in which the sound generating body (2) outputs the sound wave signal, the echo body being provided at a position where said sound wave signal resonates at a predetermined frequency; a slit (5) that is provided between the sound generating body (2) and the echo body (3), and through which sheet-form paper money (4) passes; and a resonance determination unit (6) that determines the state of resonance of the frequency that is output from the sound generating body (2). The resonance determination unit (6) determines the state of resonance by detecting changes in the power consumption of the sound generating body (2). |
