| 摘要 |
PURPOSE:To enable the detection of breakage or other abnormality of a ceramic filter accurately and reliably by inexpensive equipment, by a method wherein an internal sound of a drum wherein the ceramic filter is held is detected by a vibration pickup and passed through a compensator. CONSTITUTION:A vibration pickup 2 is fitted to a drum 1 wherein a number of ceramic filters are fitted, and thereby an internal sound of the drum 1 is detected constantly. The detected internal sound of the drum 1 is amplified by a preamplifier 3. The internal sound detected when the ceramic filters are clean shows a prescribed frequency distribution, while it contains a wide range of sounds of frequencies other than ones in a normal frequency region in the case when breakage or any other abnormality occurs in the ceramic filters. Accordingly, the internal sound amplified by the amplifier 3 is passed through a compensator 4, so that only a sound in the region of abnormal frequencies be taken out while a sound in the region of normal frequencies is cut. A sound pressure level of the abnormal sound thus taken out is compared with a set value preset by an alarm setting unit 5, and an alarm signal is delivered when any abnormal sound exceeding the set value is detected. |
