JPH03260961A - Magnetic disk inspection instrument - Google Patents

Abstract

PURPOSE:To perform the inspection of a missing bit error, an extra bit error, and bit shift in a magnetic disk by comparing a recording pattern with a reproducing pattern. CONSTITUTION:The current amplification of a signal (a) outputted from a test pattern generation circuit 11 is performed by a reproducing write amplifier 2, and the signal is written on the magnetic disk 13 by using a magnetic head 1. Next, written data is picked up by the head 1, and voltage amplification is performed by the write amplifier 2, and a binary signal (d) can be obtained at a binarization circuit 4. Following that, a reference clock (e) is reproduced by passing the signal (d) through a PLO circuit 5, and an inspection window signal (f) is obtained from the clock (e) by a window generation circuit 6. A window comparator 7 compares whether or not the signal (d) is within the range of the signal (f), and when the signal (d) is included in the signal (f), a normal reproducing signal (g) is outputted. Next, a signal (g) is compared with a write pattern (c) that is the output of the circuit 11 by a pattern compara tor 12, and it is recorded on an error RAM 8 as a defect when noncoincidence is obtained between them.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk testing device, and 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 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; A window generation circuit 6 that generates an inspection window from the output of the PL○ circuit 5 and a window comparison circuit 7 that compares the output of the window generation circuit 6 with the output of the binarization circuit 4. Defect RAM for recording defects detected by the window comparison circuit 7
Consists of 8.

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 window generating circuit 6 does not receive the 1% 4 output of the binary conversion circuit, it becomes a defect.

The output of the magnetic head 1 is amplified by the R/W amplifier 2, binarized by the binarization circuit 4, a reproduced clock is generated by the PLO circuit 5, an inspection window is generated by the window generation circuit 6 from the reproduced clock, and the window comparison circuit is performed. FI! 47, the output of the P I-○ circuit 5 is sampled by the output of the binary circuit 4 to detect defects, and the detected defect information is stored in the defect RAM.
Record on 8.

[Problem to be solved by the invention]

The conventional magnetic disk inspection apparatus described above detects defects based on the reproduced signal, and therefore has the disadvantage that it cannot detect extra bit errors and missing bit errors due to medium defects.

[Means to solve the problem]

A magnetic disk inspection apparatus of the present invention is a magnetic disk defect inspection apparatus that writes and reproduces data on a magnetic disk and inspects writing and reproduction margin defects on the magnetic disk. a 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) writing from the playback clock. - A window generation circuit that generates a window for inspecting the reproduction margin; (E) A window comparison circuit that compares the output of the window generation circuit with the output of the binarization circuit; (F) A write signal to the reproduction/write amplifier. (G) a pattern comparison circuit that compares the output of the window comparison circuit and the light pattern generation circuit; (H) a pattern comparison circuit that compares the output of the window comparison circuit and the output of the light pattern generation circuit; Defect R to record defects
It is composed of AM, and.

〔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.

The magnetic disk inspection apparatus shown in FIG. 1 writes a signal a outputted from a write pattern generation circuit 11 to a magnetic disk 13 using a reproduction W writing amplifier 2 with a current of 11 V, <L, and a magnetic head 1.

Next, the data written as described above is picked up by the magnetic head 1, voltage amplified by the reproducing/writing amplifier 2, and a binarized signal d is obtained by the binarizing circuit 4.

The binary signal d is passed through a PLO circuit 5 to reproduce a reference clock e, and a window generation circuit 6 obtains a test window signal f from the reference clock e.

The window comparison circuit 7 compares the binarization circuit output d and the window generation circuit 6 output f to see if the binarization output d signal is within the range of the window signal f, and determines whether the binarization circuit output f is within the window f. If it is, a normal reproduction signal g is output.

Next, the pattern comparison circuit 12 compares the normal reproduction signal g and the write pattern C output from the write pattern generation circuit 11, and if they do not match, it is determined that the error RAM 8 is defective.
to be recorded.

〔Effect of the invention〕

The magnetic disk inspection apparatus of the present invention has the advantage of being able to detect missing bit errors, extra bit errors, and bit shifts in magnetic disks by comparing recorded patterns and reproduced patterns.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an 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...
-Write pattern generation circuit, 12...pattern comparison 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) sends a write signal to the playback/write amplifier; a write pattern generation circuit that generates a pattern comparison signal during reproduction; (G) a pattern comparison circuit that compares the output of the window comparison circuit and the write pattern generation circuit; (H) records defects detected by the pattern comparison circuit; Defect R
A magnetic disk inspection device comprising: AM.