JP2720225B2 - Error check method for magnetic disk tester - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an error inspection method for a magnetic disk tester, and more specifically, to remove a noise from an average voltage of a read voltage for one round of a track to obtain a correct average voltage. The present invention relates to an inspection method in which calculation and control of a calculated value, a coefficient multiplied by a coefficient, and a reference voltage of a comparator are computerized.

2. Description of the Related Art A hard magnetic disk (hereinafter simply referred to as a magnetic disk) used in a computer system is inspected by a magnetic disk tester because an error occurs in data if the medium has a defect.

An error checking method for a magnetic disk will be described with reference to FIGS. FIG. 1A shows a basic configuration of a magnetic disk tester, in which a magnetic head 2a, a magnetic head 2a,
The test signal is written / read by the amplifier 2b.
The read test signal SR includes a missing error in which the waveform disappears due to a defect in the magnetic disk, a spike error in which the amplitude of the waveform is larger than a reference value, and a modulation error in which the amplitude periodically fluctuates. When reading is performed after erasing data, there is an extra error caused by incomplete erasing. In the error check, as shown in FIG. 2B, the read test signal SR is input to the average value measuring circuit 3 to calculate an average voltage (hereinafter abbreviated as TAA) for one round of the track. This average value measuring circuit is a known hardware circuit configured by an integrating circuit or the like. TAA is input to the reference voltage generation circuit 5 through the level adjustment resistor 4 and is then input to the microprocessor (MPU).
The reference voltage vL is created by multiplying by an appropriate coefficient given by 9 and is given to the + terminal of the comparator 6. On the other hand, the test signal SR is applied to the-terminal, and the two are compared. In FIG. 7C, in measuring the spike error, the reference voltage is set to vLs higher than TAA. The peak value of the waveforms (a) and (c) of the test signal SR is the reference voltage vLs
Although the output of the comparator 6 is smaller than that, the waveform (b) exceeds this, and thus a detection pulse is output. On the other hand, in the measurement of the missing error, the reference voltage is set to vLm lower than TAA, and the waveform exceeding this (a),
(B) A detection pulse is output, but the waveform (c)
Is not output because it does not reach this. Error determination circuit 7
In, the detection pulse of the comparator is checked at a timing synchronized with the test signal SR, the waveform (b) is determined to be a spike error, and the waveform (c) is determined to be a missing error.
Will be recorded. It should be noted that the modulation error and the extra error are almost the same, and thus the description is omitted.

In the above, since the TAA is not a fixed value but changes for each magnetic disk and track, an appropriate number of test tracks 1a are sampled from a large number of tracks for each magnetic disk, and the above-described error check is performed for each test track. Since there are various types of errors, and the number of test tracks is large and the inspection takes a considerably long time, in order to reduce the inspection time, in an actual magnetic disk tester, a plurality of necessary components such as a comparator 6 are arranged in parallel. And various error checks are performed as simultaneously as possible.

[Problem to be Solved] Since the number of detected errors greatly varies depending on the reference voltage vL, a coefficient multiplied by the TAA is made in increments of% to produce a reference voltage vL at a minute interval, thereby achieving highly accurate error measurement. Is performed. However, the magnetic head 2a
As shown in FIG. 3 (a), the signal read out includes noise NR of the disk 1 and the amplifier 2b in addition to the test signal SR. The output voltage of the circuit 3 becomes TAA 'including an error of the noise NR, and an error occurs in an error measurement requiring high accuracy. On the other hand, conventionally, an error is measured by giving an appropriate reference voltage to a comparator in advance, and a correct TAA is estimated from the obtained error data, thereby performing error measurement without error. FIG. 3 (b) illustrates a method of estimating TAA. First, an appropriate stage coefficient is set in the reference voltage generating circuit 5, and the test signal SR of the test track to be inspected is input to the average value measuring circuit. Then, the output voltage is multiplied by the above coefficient to change the reference voltage vL stepwise, and the number of spike errors Em and the number of missing errors Em detected are measured. The curve in the figure plots the reference voltage vL on the horizontal axis and the number of detected errors on the vertical axis, where Es and Em are the reference voltage.
Although vL increases sharply as it approaches TAA (unknown), both curves have the characteristic of being symmetrical with respect to the horizontal axis as shown in the figure due to the random distribution of errors. The reference voltage should indicate TAA. As a result, the correct TAA is estimated, and the adjustment resistance rv shown in FIG.
4 is adjusted to give the correct TAA to the reference voltage generating circuit 5.

Conventionally, the creation of the above error curve, the estimation of the TAA and the adjustment of the adjustment resistance rv are manually performed, but the manual work on a large number of test tracks is extremely complicated and time-consuming, and is inefficient. It is demanded that this be computerized to improve the inspection efficiency.

The present invention has been made in view of the above, and provides a programmable gain controller for error inspection of a magnetic disk tester, which is computerized, and removes noise included in the TAA to set a correct TAA. The purpose is to provide.

Means for Solving the Problems According to the present invention, a test signal is written / read to / from a track of a magnetic disk to be inspected, an average value measuring circuit calculates an average voltage of a read signal for one round of the track, and a reference voltage. The reference voltage is created by multiplying the average voltage by a coefficient in percent by the creation circuit, and the reference voltage and the read voltage of the test signal are compared by a comparator. is there. MPU for magnetic disk tester
A programmable gain controller controlled by First, a preliminary measurement is performed, and for each test track of the magnetic disk under test, the output voltage of the average value measurement circuit is changed at appropriate intervals to measure the error distribution characteristics, and is included in the read voltage from the distribution characteristics. The correct average voltage is obtained by removing the error due to the noise. Next, in the error check, under the control of the programmable gain controller, the correct average voltage for each test track is input to the reference voltage generating circuit, and the test signal is checked for errors.

The measurement of the distribution characteristic of the error in the above preliminary measurement is as follows.
This is performed for a spike error and a missing error, and the reference voltage with respect to the center line of the distribution curve of the spike error and the distribution curve of the missing error, which is symmetrical with respect to the reference voltage, is a correct average voltage.

[Operation] In the above-described error inspection method, a preliminary measurement is first performed, and a distribution curve of a spike error and a missing error is measured for a test track of a magnetic disk to be inspected by changing a reference voltage at an appropriate stage. Then, the reference voltage with respect to the center line of both curves is estimated to be a correct average voltage from which noise has been removed. In error measurement, a microprocessor controls the programmable gain controller to input the correct average voltage to the reference voltage generation circuit and performs error-free error inspection.Controls the programmable gain controller and creates each distribution curve , The calculation of the reference voltage for the center line of both curves and the estimation of the correct average voltage are all automatically performed by the MPU and are performed accurately in a short time, so that the inspection time is greatly reduced and the error inspection is performed with high accuracy. be able to.

Embodiments FIGS. 1A and 1B show a basic block configuration diagram and a schematic flowchart of an inspection procedure in an embodiment of an error inspection system for a magnetic disk tester according to the present invention. FIG. 2A shows the same components as those of the magnetic disk tester shown in FIG.
The description of the function of the same component is omitted. In the present invention,
In the above configuration, switches 10a and 10b are provided between the average value measuring circuit 3 and the reference voltage generating circuit 5, and M
Connect a programmable gain controller (PGC) 11 controlled by PU9. The PGC is manufactured by a single chip, and a commercially available one can be used, and the description thereof is omitted.

The error checking method will be described with reference to FIGS. 1 (a) and 1 (b). A test signal is written by a magnetic head 2a and an amplifier 2b to a test track (TR) 1a of a magnetic disk 1 to be inspected. It is. On the other hand, preliminary measurement is performed first, and the MPU 9 sets a coefficient of an appropriate stage in the reference voltage generation circuit 5. The read test signal SR
Is input to the average value measuring circuit 3 and the average voltage for one round of the track is measured.
10a and 10b are directly connected, the output voltage of the average value measuring circuit 3 is directly input to the reference voltage generating circuit 5, and the output voltage is multiplied by the above coefficient to generate a reference voltage vL. And the test signal SR applied to the-terminal
, The spike error Es and the missing error Em are detected, and the data is stored in the memory 8. It is determined whether or not the stepwise change of the coefficient by the MPU 9 has been completed. If the step change has not been completed, the process returns to the step, a new coefficient is set, and the above processing is repeated. When processing for all coefficients is completed, Es and Em stored in the memory
The error distribution curve of FIG. 3 (b) is created by the MPU from the above data, and the correct TAA from which the noise component has been removed from the center line of both distribution curves is calculated. For all TR
After the TAA is calculated, the operation shifts to the actual measurement. In the actual measurement, the switches 10a and 10b are switched to connect the PGC 11, the PGC is controlled by the control of the MPU to correct the output voltage of the average value measurement circuit to TAA, and the reference voltage generation circuit 5 Set the coefficient in percentage increments for the reference voltage vLs or vLm. Then, reading is performed on TR, and the average voltage of the test signal SR for one round of TR is measured by the average value measuring circuit. This average voltage is corrected to the correct TAA by the PGC and input to the reference voltage generating circuit.
The reference voltage vLs or vLm is output and provided to the comparator 6, whereby Es or Em is measured and stored in the memory. When the measurement for all TRs is completed,
The error check on the magnetic disk is completed, and the measurement data stored in the memory is edited into a predetermined format and output.

In the above embodiment, the block configuration of the circuit is basic. In an actual magnetic disk tester, a plurality of comparators 6 and the like are provided in parallel, and each error is checked at the same time. Although the flowchart is a schematic one, the configuration of the steps is actually complicated and the order may be changed, but the gist of the present invention is understood above.

[Effects of the Invention] As is clear from the above description, in the error checking method according to the present invention, a computer is provided with a programmable gain controller, and a spare is provided for a test track of a magnetic disk to be tested. The distribution curve of both spike error and missing error is measured, and the reference voltage with respect to the center line of both curves is the correct average voltage without noise.The correct average voltage is controlled by the programmable gain controller and the reference voltage generation circuit The conventional manual tasks such as controlling the programmable gain controller, measuring each distribution curve, and calculating the correct average voltage are all performed automatically and accurately by the MPU. , Efficient and high-precision error inspection by magnetic disk tester There are significant effects that contribute to the development.

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) are a basic configuration diagram of a circuit and an outline flowchart of a processing procedure for an embodiment of an error checking method of a magnetic disk tester according to the present invention, and FIGS. 2 (a), (b) and FIG. 3 (c) is a conventional basic configuration diagram of a magnetic disk tester and an explanatory diagram of an error checking method using the same, and FIGS. 3 (a) and 3 (b) show noise included in a tester signal and noise due to an error distribution curve. It is explanatory drawing of a removal method. DESCRIPTION OF SYMBOLS 1 ... Magnetic disk, 1a ... Test track (TR) 2a ... Magnetic head, 2b ... Amplifier, 3 ... Average value measurement circuit, 4 ... Adjustment resistance, 5 ... Reference voltage generation circuit, 6 ... Comparator, 7: Error determination circuit, 8: Memory, 9: Microprocessor (MPU), 10a, 10b: Switch, 11: Programmable gain controller (PGC), SR: Readout tester signal, vL ... … Reference voltage, TAA… Average voltage of one track of track, NR… Noise, Es… Spike error, Em… Missing error, …… Step number in flowchart.

Claims (2)

(57) [Claims] 1. A test signal is written / read to / from a track of a magnetic disk to be inspected, an average value measuring circuit calculates an average voltage of a read signal for one round of the track, and a reference voltage generating circuit calculates the average voltage of the read signal. In a magnetic disk tester that performs a test on an error of the test signal by comparing the reference voltage with a read voltage of the test signal by using a comparator to generate a reference voltage by multiplying the coefficient by a factor of%, the microprocessor is controlled by a microprocessor. A programmable gain controller is provided, and for each test track of the magnetic disk, the output voltage of the average value measuring circuit is changed at appropriate intervals to measure the distribution characteristic of the error, and the read voltage is determined from the distribution characteristic. Preliminary measurement to find the correct average voltage, eliminating errors due to noise contained in Controlled by programmable gain controller takes characterized in that checks for errors in the test signal the correct average voltage for each test track is inputted to the reference voltage generating circuit,
Error checking method for magnetic disk testers. 2. The distribution characteristic of an error in the preliminary measurement is measured for a spike error and a missing error, and the distribution curve of the spike error and the center line of the distribution curve of the missing error are symmetric with respect to the reference voltage. 2. An error inspection method for a magnetic disk tester according to claim 1, wherein an upper reference voltage with respect to the error is the correct average value voltage.