| 摘要 |
PURPOSE:To obtain a magnetic head which can detect an AE signal with high S/N, high reliability and low cost and a magnetic disk device which has a detecting function for abnormal contact with a magnetic disk, by using a flexible printed board to form a signal extracting lead wire of an AE sensor. CONSTITUTION:The signal lines 13 including earth wires led out of the electrodes of plural AE sensors 12 are connected in parallel on a flexible printed board 18. Thus the number of signal extracting lead wires is decreased to an amplifier 23 set outside a container. As a result, the output signals given from the sensors 12 are led to the amplifier 23 via a junction circuit 20 with no reduction of the S/N. In other words, plural pairs e.g. four pairs of connections parts 16a and 16b are set in parallel on the surface of the board 18 to those signal lines and earth wires led from the sensors 12. Furthermore the parts 16a and the parts 16b are connected in common with each other into a common signal line 19a and a common earth line 19b respectively through a wiring pattern 19.
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