| 摘要 |
PURPOSE:To measure the internal pressure of a metallic container to be inspected accurately by providing a permanent magnet and a search coil between an energizing coil, which flows a single pulse current, and the end plate of said container and detecting current variations of the search coil. CONSTITUTION:A single-pulse current source 4 generates a pulse current to detect vibrations of a metallic end plate, forming the metallic lid of an airtight container 1, such as canned provisions, in a carboard case 2, by applying a single magnetic-force pulse. A magnetic core 7 wound with an energizing coil 5 forms a magnetic path together with an iron core 6, and a permanent magnet 8 is fitted atop of the magnetic core 7; and a search coil 9 is wound around a magnetic core 10 under the permanent magnet, and a cap 11 holds the magnetic core 10, search coil 9 and permanent magnet 8. A signal generated by the search coil 9 through the vibrations of the end plate 3 is processed by a signal processor 12 to discriminate the internal pressure of the metallic container 1. Thus, the size of the device is reduced, its S/N ratio is improved, and the propriety of the internal pressure is discriminated accurately. |
