| 摘要 |
PURPOSE:To reduce the soundwave itself of a noise generated from a noise source, by a method wherein a columnar vibrating system in a resonant noise- eliminating chamber is made to resonate with the soundwave of the noise generated by the noise source through a connecting part. CONSTITUTION:An impact noise occurring with the printing action of a printing part 3 is transmitted through a space inside a casing 1. Since the frequency of the main component of this transmitted soundwave coincides with the natural frequency intrinsic to a columnar vibrating system in a resonant noise- eliminating chamber 10 which connects to the space inside the casing 1 through a slit 11, the soundwave is transmitted into the noise-eliminating chamber 10 to resonate with the columnar vibrating system in the chamber 10. With this resonant phenomenon, a soundwave energy is converted to a thermal energy and, thus, an energy loss is generated and the noise level of an impact noise is reduced. Additionally, because the slit 11 is so provided as to extend over a full movable range of the printing part 3, a noise soundwave emitted from the printing part 3 reciprocating in the casing 1 during printing is reduced by resonating with the vibrating system in the noise-eliminating chamber 10 through the slit 11 regardless of a movable position of the printing part 3. |
