| 摘要 |
PURPOSE:To detect the state of contact of a head part and a disk at high accuracy by providing a sensor that detects emitted sound wave at the fixed basal part of a supporting elastic member of the head. CONSTITUTION:An acoustic emission sensor 50 that detects sound wave emitted by sound emission phenomenon at the time of destruction of molecular level of an object such as slipping of a part of crystal structure or widening of cracks in the object is fixed at the basal part of an armlike elastic member 6. Sound wave emitted when the head part 4 is brought into contact with a transparent disk 3 is detected by the AE sensor 50 through the elastic member 6, and amplified by a sound signal processing circuit 51 and converted to digital signals S12, and given to a central processing unit 15 constituted of a microcomputer. Here, the stronger the contact between the transparent disk 3 and the head part 4, the greater the destruction of the object looked in molecular level and detection level by the AE sensor becomes larger, and digital signals S12 corresponding to the degree of contact are given to the central processing unit 15.
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