JPS56119936A - Micro defect detecting system for magnetic medium - Google Patents

Abstract

PURPOSE:To enable a micro defect to be surely detected by relatively moving the position of a write clock for the micro defect. CONSTITUTION:The clock (a) of a reference disc 1 is read out with a magnetic head 2 and is inputted to a write clock selecting circuit 6. The circuit 6 generates the write clock of an arbitrary position with a write clock selection instructing circuit 5 and supplies the clock to a write pattern generating circuit 7. A write amplifier 8 writes data to the magnetic medium 12 to be tested by way of a magnetic head 11 or the like at the write pattern instructed from said circuit 7 by the current supplied from a write current generating circuit 9. Next, these data are amplified 13, whereby a reproduced signal (e) is obtained. The reproduced signal (e) is outputted as a waveform (f) and is supplied to a variable resistor 16. Here, the signal (e) is compared 17 with the one set at an arbitrary slice level, by which a waveform (g) is obtained. The signal (g) triggers a monostable multi 18. If even one of the pulse trains of the signal (g) is lacked, the waveform (h) deforms and is decided as an error.