JPH03260960A - Magnetic disk inspection instrument - Google Patents

Abstract

PURPOSE:To improve the reproducibility of a defective position in re-inspection by recording an index signal on a disk when inspection is started. CONSTITUTION:The index signal (a) from an index generation circuit is written on a magnetic disk 13 with a magnetic head 1 via an R/W amplifier 2 when the inspection is started. Following that, the output (b) of a write signal generation circuit 3 is written on the disk 13 immediately behind the index signal (a) via the amplifier 2. Next, the output of the magnetic head 1 is binarized by a binarization circuit 4 via the amplifier 2. A binary signal (d) is sent to a window comparator 7 via a PLL circuit 5 and a window generation circuit 6. The comparator 7 compares a window signal (f) with the binary signal (d), and records it on an error RAM 8 as a defect when no signal (d) is included in the signal (f). When the re-inspection is performed, write reproduction is performed immediately after detecting an index by an index detection circuit 12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk testing device, and more particularly to a magnetic disk testing device that can be applied to bit shift testing of magnetic characteristics.

[Conventional technology]

Conventional magnetic disk inspection equipment consists of a magnetic head, a playback/
It is composed of a write amplifier, a write signal generation circuit, a binarization circuit, a PLO circuit, a window generation circuit, a window comparison circuit, and a defective RAM.

Next, a conventional magnetic disk inspection apparatus will be described in detail with reference to the drawings.

FIG. 2 is a block diagram showing an example of a conventional magnetic disk inspection device.

The magnetic disk inspection apparatus shown in FIG. 2 includes a magnetic head 1 that writes to and reproduces data from a magnetic disk, an R/W amplifier 2 that sends a write signal to the magnetic head 1 and amplifies a reproduced signal, and an R/W 3. A write signal generation circuit that sends a write signal to the amplifier 2; a binarization circuit 4 that binarizes the output of the R/W amplifier 2; a PLO circuit that generates a reproduced clock from the output of the binarization circuit 4; and 5. A window generation circuit 6 that generates an inspection window from the output of the PLO circuit 5;
Output binarization circuit 4 Window comparison circuit 7 for comparing outputs
．． Defect R that records the defect detected by the window comparison circuit 7
It is composed of an AM8, a spindle 9 that rotates the disk, and an index circuit 10 that outputs the origin of the spindle.

FIG. 3 is a waveform diagram showing an example of defect detection.

Comparing the output of the binarization circuit 4 with the output of the window generation circuit 6,
If the output of the binarization circuit 4 does not enter the output of the window generation circuit 6, it is a defect.

The output of the magnetic head is increased by 1 in the R/W amplifier 2, binarized in the binarization circuit 4, a reproduced clock is generated by the PLO circuit 5, and an inspection window is generated from the reproduced clock by the window generator circuit 6, and the window is The comparison circuit 7 samples the output of the PLO circuit 5 using the output of the binarization circuit 4 to detect defects, and records the detected defect information in the defect RAM 8.

The inspection is performed in synchronization with the output of the spindle index circuit 10.

[Problem to be solved by the invention]

The above-mentioned conventional magnetic disk inspection apparatus uses a spindle index to detect defect positions, and therefore has the disadvantage that reproducibility of the same bit is poor due to jitter of the spindle index during re-inspection.

[Means to solve the problem]

A magnetic disk inspection apparatus of the present invention writes and reproduces data on a magnetic disk, and inspects writing and reproduction margin defects on the magnetic disk. -Write amplifier; (B) A binarization circuit that binarizes the playback output of the playback/write amplifier; (C) A PLO circuit that generates a playback clock from the output of the binarization circuit; (D) From the playback clock. a window generation circuit that generates a window for inspecting the write/playback margin; (E) a window comparison circuit that compares the output of the window generation circuit with the output of the binarization circuit; (F) writes to the playback/write amplifier. A light pattern circuit that sends a signal, (G) an index generation circuit that generates an index signal at the start of an inspection, (H) an index detection circuit that detects an index during an inspection, and (I) a window comparison circuit that detects defects detected by the Defective RAM to record.

It consists of:

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

In the magnetic disk inspection apparatus shown in FIG. 1, at the start of inspection, an index signal a generated by an index generation circuit 11 is current-controlled by a reproducing/writing amplifier 2 and written onto a magnetic disk 13 by a magnetic head 1. Immediately after the index signal a, the output of the write signal generation circuit 8 is current-controlled by the reproducing/writing amplifier 2, and data is written onto the magnetic disk by the magnetic head l.

The current written by the above operation is picked up by the magnetic head 1, voltage amplified by the read/write amplifier 2, and binarized by the binarization circuit 46-.

The output d of the binarization circuit 4 is used to generate a reference clock e by the PLO circuit 5, the reference clock e is used to generate the window signal f by the window generation circuit 6, and the window signal f and the binarization signal d are converted by the window comparison circuit 7. Compare and binarize signal d
If it is not within the window signal f, it is recorded in the error RAM 8 as a defect.

At the time of re-examination where the window comparison is started immediately after the index detection circuit 12 detects the index, the index detection circuit 12 performs writing and reproduction in the same manner as described above immediately after the index detection.

〔Effect of the invention〕

The magnetic disk inspection apparatus of the present invention has the effect of improving the reproducibility of defect positions during re-inspection by writing an index signal on the disk at the start of inspection.

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is a block diagram showing a conventional example, and FIG. 3 is a waveform diagram showing an example of a defect.

1...Magnetic head, 2...Reproducing/writing amplifier,
3... Write signal generation circuit, 4... Binarization circuit, 5
... PLO circuit, 6... Window generation circuit, 7...
・Window comparison circuit, 8...Error RAM, 11...
- Index generation circuit, 12... index detection circuit.

Claims (1)

[Scope of Claims] A magnetic disk defect inspection device that performs writing and reproduction on a magnetic disk and inspects writing and reproduction margin defects on the magnetic disk, comprising: (A) a reproduction/writing amplifier that writes and reproduces data on the magnetic disk; (B) a binarization circuit that binarizes the playback output of the playback/write amplifier; (C) a PLO circuit that generates a playback clock from the output of the binarization circuit; (D) a write/playback margin from the playback clock. (E) a window comparison circuit that compares the output of the window generation circuit and the output of the binarization circuit; (F) a light that sends a write signal to the playback/write amplifier. a pattern circuit, (G) an index generation circuit that generates an index signal at the start of an inspection, (H) an index detection circuit that detects an index at the time of inspection, and (I) a defect RAM that records defects detected by the window comparison circuit. A magnetic disk inspection device comprising: