| 摘要 |
PURPOSE:To contrive reduction in noise and a smaller device, by a construction wherein an inlet to a bent passage of an interference-type soundproofing device is opened in an outlet passage so that a portion of the noise passing through the outlet passage is passed through the bent passage, whereby a direct propagating sound and a refracted propagating sound are made to interfere with each other. CONSTITUTION:The noise emitted through a printing paper outlet 4 is divided into the direct propagating sound A passing through the outlet passage 8 and the refracted propagating sound B passing through the bent passage 10 of the interference-type soundproofing device 6. In this case, since the refracted propagating sound B passes through the bent passage 10 having a length different from the length of the outlet passage 8, the phase of the sound B is shifted from the phase of the direct propagating sound A. Due to the phase shift, the sound A and the sound B interfere with each other, forming an interference sound-reducing region C. Accordingly, the noise emitted through the paper outlet 4 of the printer can be reduced. |
