JP3392686B2 - Method and apparatus for inspecting wiggle characteristics of magnetic head - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for inspecting a wiggle characteristic of a magnetic head, and more specifically,
The present invention relates to a method and an apparatus for inspecting a wiggle characteristic of a magnetic head, which can inspect a wiggle of a thin film magnetic head or an MR magnetic head (MR head) in a short time.

[0002]

2. Description of the Related Art In recent hard disk devices, a thin film head is used as a write side head and an MR head is used as a read side head. The same applies to a thin-film head only, but particularly in an MR head, the width of the read signal varies when reading is performed after writing. This is the characteristic of a magnetic head called so-called Uighur. If this amplitude fluctuation is large, an error will occur in the read data.
After the magnetic head is manufactured, the quality of the Uighur characteristic is inspected. With reference to FIGS. 5 and 6, the conventional generation of wiggle of a magnetic head and its inspection method will be described.

FIG. 5 shows a write current (FIG. 5A) by a thin film head on the write side, and correspondingly when the thin film head or MR head reads write data from a track of a magnetic disk. The waveform of the read signal (FIG. 5B) is shown. Usually, the read signal voltage V is measured by peak-to-peak, but at this time, a phenomenon called wiggle occurs in which the amplitude of each positive and negative peak fluctuates (see the dotted line waveform). Therefore, the wiggle inspection of the magnetic head is performed according to the procedure shown in FIG. 6. FIG. 6 is a flowchart of the inspection procedure at the time of the Uighur inspection of the control device.

First, the head is positioned on a certain inspection track TR, and this inspection track TR is DC erased (step 101). Then, a predetermined test code for one rotation of the disk is written on the entire inspection track TR (step). 1
02). Then, the average output voltage for one revolution (one track) of the track TR is measured and stored in the memory (step 103). In order to detect the average output voltage for one track, the peak-following detection circuit corresponding to each peak in order to measure the read signal voltage V in FIG. 5B follows the positive peak and the negative peak. This is performed by detecting the read voltage. Measurement of the average output voltage is determined from the voltage value detected by the peak-following the detection circuit. Next, in step 104, it is determined whether or not the measurement is performed m times, and when the measurement is not completed m times, the process returns to step 102, a predetermined test code is written, and the same operation is repeated m times. In this case, m is usually 5
It is about 0 to 100 times.

When the repeated measurement of m times is completed, the measured value of the average output voltage for each time of the inspection track TR is stored in the memory. Therefore, the variation σ of each measurement value is calculated from the measurement data of m times by statistical processing, the maximum value and the minimum value are detected, and the average value is calculated (step 105), and each calculation is performed in the Uighur determination processing. It is determined whether the value is within a predetermined reference value range (step 106). In this way, the magnetic head Uighur inspection is performed, and the pass / fail of the magnetic head is determined by the combination of the results of the determinations in step 105.

An MR head (magnetoresistive effect head)
An example of the peak-following detection circuit for is shown in FIG. In the figure, the peak-following detection circuit on the negative side is omitted. This is because the circuit configuration is substantially the same only by receiving the output on the opposite phase side from the read amplifier (AMP) 31 configured by a differential amplifier.
The positive side peak-following detection circuit 30 will be briefly described. The positive side output from the read amplifier 31 is received by the comparator (COMP) 32 and the voltage and the input voltage of the capacitor C provided on the output side. A current corresponding to the difference between the current and the current is applied to the input transistor Tr2 of the current mirror 33 via the transistor Tr1. Then, the capacitor C is charged by the output transistor Tr3 of the current mirror 33. Alternatively, the electric charge of the capacitor C is discharged by the current i generated by the current source 34. As a result, the voltage of the capacitor C is obtained at the terminal of the capacitor C as a voltage that follows the input voltage of the comparator 32 . The voltage of the capacitor C is applied to the A / D conversion circuit 36 via the voltage follower 35 composed of an operational amplifier and output as a digital value to the control device or the like. The voltage detected by such a circuit becomes a voltage that follows each peak of the waveform as shown in FIG. V in the waveform shown by the dotted line in the figure
p is the output voltage of the detection circuit 30, and Vi of the waveform shown by the solid line is the input waveform of the comparator (COMP) 32.

[0007]

However, in such a Uyghur inspection method, unless the measurement is repeated 50 to 100 times as m times, there is not enough information to judge the quality of the magnetic head. Particularly, in the MR head, as shown in FIG. 7, it is necessary to measure the average value on the positive electrode side and the average value on the negative electrode side, respectively. MR
This is because the head can be a target of determination even for the symmetry of the output voltage. Because of this, there is a problem that the Uighur inspection takes time. An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a method and an apparatus for inspecting a wiggle characteristic of a magnetic head, which can inspect the wiggle in a short time.

[0008]

The present invention for achieving the above object is characterized by a Uighur characteristic inspection method and an inspection apparatus which are characterized by n arbitrary tracks (n is an integer of 2 or more) of a magnetic disk. After dividing into the area and writing a predetermined test code on the whole track, Uighur characteristic inspection
Write at the beginning of the divided area, and then
Reading said predetermined test code written Te, to the average value of the output voltage of the peak measurement to obtain the n regions corresponding m times (m is an integer of 2 or more) repeating, n regions corresponding obtaining a value corrected by the correction coefficient that corresponds to the region for the mean value of the output voltage of, be those inspecting the wiggle characteristic of the magnetic head based on the obtained value
The above correction factor is written in the entire track.
Read the constant test code for one track and find the peak
The average value of all output voltages and the peak of each of the n regions
To obtain the ratio of the output voltage to the average value,
This is obtained for n areas. In addition, the above
The correction factor corresponds to any one of the above-mentioned m measurements
A predetermined test code is written on the entire track and this
This can be done by reading out one track.

[0009]

DETAILED DESCRIPTION OF THE INVENTION Thus, by dividing the test track writing the test code into n performs writing at the beginning side of the divided regions, reads the test code written prior to subsequent
Thus, the average value of n output voltages required for Uighur measurement can be obtained by one measurement. As a result, the number of measurements can be reduced by n-1. However, since the average value of the output voltage of each region divided into n pieces obtained at this time is not the average value obtained from a lot of data like the average value of the output voltage of one track of the related art, the magnetic disk is Is susceptible to output fluctuations caused by imbalance of the magnetic film, so-called modulation. Therefore, it cannot be used as it is as accurate average value data of the output voltage.

Therefore, any one of the measured values of the m measurements or the correction coefficient for eliminating the influence of the modulation is separately obtained for each of the n divided regions.
The correction coefficient in this case is the ratio between the average value of the output voltage of the entire inspection track TR and the average voltage value of each divided area. Such a correction coefficient is corrected in correspondence with n divided areas with respect to the average value of m × n output voltages or the remaining (m−1) × n output voltages in m measurements. By doing so, the average value of the output voltage of each divided region can be treated as the average value of the output voltage similar to the conventional one. As a result, theoretically, m × n times or (m−1) × n times of data can be obtained even if the number of measurements m is reduced.
The actual Uighur inspection time can be shortened.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an inspection apparatus to which the magnetic head Uighur characteristic inspection method of the present invention is applied, and FIG.
FIG. 3 is a flowchart of the inspection process, FIG. 3 is an explanatory diagram of the relationship between the write / read signal, modulation, and the state of the disk, and FIG. 3A is an explanatory diagram of the read voltage of the inspection track of the magnetic disk. 4B is an explanatory view of the write / read area in the inspection track of the magnetic disk, FIG.
6A and 6B are timing signals and operation explanatory diagrams for explaining writing / reading of a divided area, FIG. 9A is an explanatory diagram of an indenss signal thereof, and FIG. 9B is an explanatory diagram of a write control signal.
(C) is an illustration of writing, reading, and divided areas, and (d) is
It is explanatory drawing of the correction coefficient about each divided area. In FIG. 1, reference numeral 1 denotes a magnetic head, which comprises an inductive thin film head 1a for writing and an MR head 1b for reading. The thin film head 1a receives the data of the test code from the write data creation circuit 3 via the write circuit 2a in the write / read control circuit 2 and transfers it to a predetermined inspection track TR of the magnetic disk 20 (hereinafter referred to as disk 20). Write the test code. Reference numeral 21 is a spindle motor that rotates the disk 20, and reference numeral 22 is an encoder (ENC) that outputs the rotation reference signal and the rotation amount of the disk 20 as an angle signal in pulses.

Reference numeral 4 is a write data memory, and the write data generating circuit 3 is responsive to a control signal ST from the control device 5.
Access to read predetermined test data corresponding to the designated test code and send it to the write circuit 2a. 6
Is a head drive mechanism, which includes a positioning mechanism such as a carriage for moving the magnetic head 1 to the track of the disk 20. The MR head 1b writes / reads out the test code written from the inspection track TR.
The signal read out by the readout circuit 2b in FIG. 2 and amplified here has a high-frequency noise component removed through a low-pass filter (LPF) 7, and is amplified by a differential amplifier (AMP) 8 to have two phases different by 180 degrees. It is output as a signal. The configuration of the read circuit 2b, the low-pass filter (LPF) 7 and the differential amplifier (AMP) 8 here is shown in FIG.
It corresponds to the amplifier 31 in. Differential amplifier (AM
The positive and negative phase output signals of P) 8 are input to the peak tracking type detection circuit 9 described in FIG.

The peak follow-up detection circuit 9 comprises a positive peak follow-up detection circuit 9a and a negative peak follow-up detection circuit 9b which follow the positive peak, and the positive peak follow-up detection circuit 9a.
a receives the positive phase side output from the differential amplifier 8, and the negative peak follow-up detection circuit 9b receives the negative phase side output from the differential amplifier 8. Each output voltage value is the A / D conversion circuit (A / D
D) The signals are inputted to 10a and 10b, respectively, and the respective signals are sampled at a predetermined cycle in accordance with the sampling signal SL from the timing signal generating circuit 12 and taken into the memory circuits 11a and 11b. The timing signal generation circuit 12 associates the sampling signal SL with a pulse indicating the amount of rotation of the disk from the encoder (ENC) 22 or a peak generated by dividing the internal clock generated in synchronization with the pulse. Occur. Each of the memory circuits 11a and 11b has an address counter therein, and the fetch control signal S from the timing signal generating circuit 12 is received.
The voltage value of the positive peak value sequentially A / D converted while incrementing the address counter according to E, for example,
The memory circuit 11a stores 8 bits at each address of the internal memory, and the A / D converted negative peak voltage value, for example, 8 bits is stored at each address of the internal memory by the memory circuit 11b. .

The timing signal generation circuit 12 sends the control signal S1 to the control device 5 assuming that the disk 20 has made one rotation when receiving the next index signal from the encoder 22. The control device 5 reads the voltage values of the positive and negative peak values of one track (one rotation of the disk) recorded in the memory circuits 11a and 11b in response to the control signal S1 from the timing signal generating circuit 12, and performs the wiggle inspection. I do. Further, the timing signal generation circuit 12 operates according to the control signals S2 and S3 from the control device 5. The control signal S2 is a control signal generated at the time of sampling the correction coefficient, and the control signal S3
Is a control signal for performing the Uighur inspection process.

First, when the timing signal generation circuit 12 receives the control signal S2 from the control device 5, the timing signal generation circuit 12 sends a predetermined control signal to the write / read control circuit 2 and the write data creation circuit 3. To write the test code for one track to the inspection track TR in accordance with the index signal INDEX (see FIG. 4A),
Next, the test code for one track is read out. When the timing signal generation circuit 12 receives the control signal S3 from the control device 5, the write control signal WS shown in FIG. 4B is indented to the write / read control circuit 2 and the write data creation circuit 3. Signal INDEX (see Figure 4 (a))
According to. The write control signal WS is a HIGH level (hereinafter "H") signal during the period t, and is generated n times per rotation in the cycle T (see FIG. 4B).

The write data creation circuit 3 is provided with a write control signal W.
When S is received, the period t during which the write control signal WS is "H"
During this period, the test code is sent to the write / read control circuit 2. When the write / read control circuit 2 receives the write control signal WS, the write / read control circuit 2 writes the test code received from the write data creation circuit 3 on the track of the disk 20 during the period t during which the write control signal WS is "H". Put in. The write / read control circuit 2 reads data from the track while the write control signal WS is at the LOW level (hereinafter "L"). As a result, the write control signal WS
According to FIG.
As shown in (c), the writing period t and the reading period (T-t)
Divided regions R1, R2, ..., Rn in which
Is generated (see FIG. 3B).

The control device 5 writes a test code on the entire inspection track TR, obtains a predetermined correction coefficient, and then sends the control signal S2 to the timing signal generating circuit 12 to divide the divided regions R1, R2 ,. Writing and reading are performed on Rn to obtain the voltage value of the read signal of each divided region. The timing signal generation circuit 12 uses the index signal INDEX.
, Rn by generating n write control signals WS in response to the write control signals WS to write into and read from the divided regions R1, R2, ..., Rn, and for each of the n divided regions in the memory circuits 11a and 11b. The read voltage data indicated by the dotted line in FIG. In order to perform such processing, in the control device 5, the MPU (microprocessor) 51, the memory 52, the display 53 and the like are connected to each other via the bus 54, and the memory circuits 11a and 11b are also connected to the bus 54.
It is connected to the. The memory 52 has a divided area correction coefficient calculation program 52a and a Uighur inspection program 52a.
b, a correction coefficient data area 52c and the like.

The MPU 51 executes the divided area correction coefficient calculation program 52a and performs the following processing. First, the MPU 51 controls the head drive mechanism 6 to position the magnetic head 1 on the inspection track TR, DC erases the inspection track TR, and erases the data on this track. Next, the control signal ST is sent to the write data creation circuit 3 to select a predetermined test code. Then, the control signal S2 from the control device 5 is supplied to the timing signal generation circuit 12
To the memory circuit 11 to write a test code to the entire inspection track TR.
Obtained from a and 11b. The read voltage at this time is partially shown as an analog value in FIG. P is a follow-up read voltage on the positive electrode side, and N is a follow-up read voltage value on the negative electrode side. The tracking voltage of each peak value has a swell (modulation). The waveform F is the LPF
7, PM is an average value for one track on the positive electrode side, and NM is an average value for one track on the negative electrode side.

Therefore, the MPU 51 includes the memory circuit 11
a, 11b are accessed to read the data, and the average voltage value PM of one track of the inspection track TR of the follow-up voltage P on the positive side and the inspection track TR of the follow-up voltage N on the negative side.
The average voltage value NM of one track of
Remember. Next, the average voltage values P1, P2, ..., Pn of the follow-up voltage P for each of the regions R1, R2, ..., Rn divided by the n write control signals WS and the n write control signals WS.
The average voltage values N1, N2, ..., Nn of the follow-up voltage N for each of the regions R1, R2, ..., Rn divided by are calculated and stored in the memory 52. Then, for each of the areas R1, PM is used as a correction coefficient with the ratio of the average voltage value of one track of the inspection track TR to the average voltage value of each divided area.
For / P1, NM / N1 and R2 , PM / P2 and NM / N2
, Rn , PM / Pn and NM / Nn are calculated and stored in the correction coefficient data area 52c of the memory 52.

Further, the MPU 51 executes the Uighur inspection program 52b and performs the following processing. First,
The control signal ST is sent to the write data creating circuit 3 to select a predetermined test code. Then, the control signal S3 from the control device 5 is sent to the timing signal generation circuit 12 to generate the write control signal WS in the timing signal generation circuit 12, and the inspection track T of the disk 20 is generated in response to this signal.
A test code is written in the leading portion of each divided area R1 of R over a period t, and immediately after the test code is written, the previous divided area correction coefficient calculation program is executed in the "L" period of the write control signal WS. 52a is executed to read out the test code in the (T-t) period from the written test code. This is sequentially performed for each of the divided areas R2, ..., Rn. As a result, the inspection track TR of the disc 1 is shown in FIG.
It becomes good Una state of (b). And the inspection truck TR
Memory circuit 11a stored for one inspection value of
11b data is accessed to generate divided areas R1, R2,
, Rn corresponding to the respective positive electrode side divided regions R1,
,, Rn average voltage values PV1, PV2, ..., PVn, and negative side divided regions R1, ..., Rn average voltage values NV1, NV2,
, NVn, and correction coefficients PM / P1, NM / N1, PM / P2, NM / N2, ...
Average voltage values * PV1, * PV2, ..., * PVn corrected by multiplying PM / Pn and NM / Nn, and * NV1, * NV2, ...,
* NVn is obtained for each of the divided areas R1, ..., Rn and stored in a predetermined area of the memory 52.

By repeating such measurement m times, n × m corrected average voltage value data corresponding to the positive electrode side and the negative electrode side are obtained. Average value voltage data * PV1, * PV of the divided areas R1, R2, ..., Rn thus obtained
2, ..., * PVn and average voltage data * NV1, * NV2,
…, * NVn and inspection track T as before
It is determined whether the variation σ from the average values PM and NM of R, the maximum value and the minimum value are within a predetermined output range, or whether the average value of each divided region voltage output is a certain value or more,
Perform Uighur inspection. It should be noted that each reference data serving as a reference for the determination here may be an appropriate value according to an actual experimental value or empirical value.

Next, the overall procedure of the Uighur inspection process of the controller 5 will be described. FIG. 2 is a flowchart of the processing. First, the MPU 51 executes the main program to call the divided area correction coefficient calculation program 52a, and then executes this to position the head on the inspection track TR. (Step 201), inspection track TR
Is erased by DC (step 202). Next, the control signal S2 is output to write the test code on the inspection track TR and one track (step 203).
The test code is read from R (step 204). Then, a correction coefficient is calculated for each of the divided areas R1, R2, ..., Rn (step 205).

Subsequently, the MPU 51 calls and executes the Uighur inspection program 52b, generates the control signal S3, writes the test code at the head position of each of the divided areas R1, R2, ..., Rn, and thereafter. By reading the read voltage into each of the divided regions R1, R2, ..., Rn (step 20).
6), an average voltage value is calculated for each of the divided areas R1, R2, ..., Rn (step 207), and each divided area R1, R2,
, Rn is corrected for the average voltage value (step 20
8) Store each correction value in the memory (step 20).
9). Then, by determining whether or not the number of measurements is m, it is determined whether or not the measurement is completed (step 210). If the result of this determination is that the number of measurements has not reached m, the determination is NO and the process returns to step 206.

When the measurement of m times is completed in this way,
If YES, the variation σ, the maximum value, the minimum value, and the average value are calculated for the corrected average voltage values of the respective divided areas R1, R2, ..., Rn (step 211),
The Uighur judgment to be compared with a predetermined reference value provided for each is entered (step 212), the judgment result is output to the display 54 or the like (step 213), and this processing ends. As for the above-mentioned measurement of m times, when the number of divisions is n = 16, the conventional Uighur measurement of about 100 times enables the Uighur inspection at 7 times of measurement. This greatly reduces the time required for Uighur inspection.

As described above, in the embodiment, the correction coefficient is obtained by the first measurement.
If the erase operation is performed, the test code is written on the entire inspection track TR, the data for the wiggle measurement is collected, and the data is stored in the memory. If the inspection track TR is DC erased on the way, the entire inspection track TR is erased. The correction coefficient can be collected by writing a test code, and finally, the correction coefficient may be collected by a similar procedure. The Uighur inspection may be determined by performing a correction process on the average value of the read voltages stored in the respective divided regions by the correction coefficient thus collected. Further, the time t at which writing is performed at the head position of each divided area can be set arbitrarily rather than a specific time, and the head position may be slightly shifted as long as a large number of read areas are provided. It is sufficient that the writing is on the head side.

[0026]

As described above, according to the present invention, the inspection track for writing the test code is divided into n tracks,
Perform writing at the beginning side of the divided regions, it reads the test code written before then, the average value of n output voltage required to wiggle measured in a single measurement is obtained, further modulation Since the correction is performed by the correction coefficient in order to eliminate the influence of, the average value of the output voltage of each divided region can be treated as the average value of the output voltage similar to the conventional one. As a result, even if the number of measurements m is reduced, theoretically m × n
It is possible to obtain double or (m-1) × n times the data, and the actual Uighur inspection time can be shortened accordingly.

[Brief description of drawings]

FIG. 1 is a block diagram of an inspection apparatus to which a magnetic head Uighur characteristic inspection method of the present invention is applied.

FIG. 2 is a flowchart of the inspection process.

FIG. 3 is an explanatory diagram of a relationship between a write / read signal, modulation, and a state of a disc, in which (a) is
FIG. 7B is an explanatory diagram of the read voltage of the inspection track of the magnetic disk, and FIG. 9B is an explanatory diagram of the write / read area in the inspection track of the magnetic disk.

4A and 4B are timing signals and an operation explanatory view for explaining writing / reading of a divided area, FIG. 4A is an explanatory view of an indentation signal thereof, and FIG. 4B is a write control. An explanatory diagram of signals, (c) is an explanatory diagram of writing, reading and divided areas,
(D) is an explanatory view of a correction coefficient for each divided area.

FIG. 5 is an explanatory diagram of a general read signal wiggle, and FIG. 5A is an explanatory diagram of a write signal;
(B) is an explanatory view of a read signal.

FIG. 6 is a flowchart of a conventional Uighur inspection process.

FIG. 7 is an explanatory diagram of an example of a peak tracking circuit.

[Explanation of symbols]

1 ... Magnetic head, 1a ... Inductive thin film head, 1
b ... MR head, 2 ... Write / read control circuit, 2a ... Write circuit, 2b ... Read circuit, 3 ... Write data creating circuit, 4 ...
Write data memory, 5 ... Control device, 6 ... Head drive machine
Structure, 7 ... Low-pass filter (LPF), 8 ... Differential Anne
Flop, 9 ... peak-tracking detection circuit, 9a ... positive peak tracking detector circuit, 9b ... negative peak tracking detector circuit, 10a,
10b ... A / D conversion circuits (A / D), 11a, 11b ...
Memory circuit, 12 ... Timing signal generating circuit, 20 ... Magnetic disk, 21 ... Spindle motor, 22 ... Encoder, 51 ... MPU (microprocessor), 52 ... Memory, 52a ... Divided area correction coefficient calculation program, 52b
... Uighur inspection program, 52c ... correction coefficient data area, 53 ... display, 54 ... bus.

Claims (5)

(57) [Claims] 1. An arbitrary number (n) of arbitrary tracks on a magnetic disk are recorded.
Is an integer greater than or equal to 2), and after writing a predetermined test code on the entire track, a Uighur characteristic test is performed.
Write at the beginning of the divided area, and then
Reading said predetermined test code written Te, the measurement to obtain the average value of the output voltage of the peak in the n regions corresponding m times (m is an integer of 2 or more) to repeatedly, the n the average value of the output voltage of the region corresponding to the region
Obtaining a value obtained by correcting the corresponding compensation coefficient, there is for inspecting wiggle characteristic of the magnetic head based on the obtained value, a predetermined test written in the entire track
The track code is read out for one track and the
The average value of the output voltage and the peak of each of the n regions.
The ratio of the output voltage to the average value of
Then, a method for inspecting a wiggle characteristic of a magnetic head, which is obtained corresponding to the n areas . 2. The correction coefficient is obtained by DC erasing the track, writing a predetermined test code on the entire track, and then reading one track of the track to obtain the output voltage of the one track of the track. The method for inspecting a wiggle characteristic of a magnetic head according to claim 1, which is calculated by obtaining an average value and an average value of the n areas. 3. The correction coefficient is an arbitrary value for the m measurements.
Corresponding to one time, the predetermined test mark on the entire track
No. is written, and this is read for one round of the track.
The Uighur characteristic test of the magnetic head according to claim 1, which is performed by
Inspection method. 4. A magnetic disk, a write / read circuit for writing a test code on a track of the magnetic disk, and reading the test code written on the track, and the write / read circuit for the write / read circuit . All over the truck
Predetermined period Masho inclusive system constant test code write and read controls and tracks of the magnetic disk of n (n is an integer of 2 or more) the divided area head side is divided into regions of
A read / write control circuit for performing read control after control , a detection circuit for generating a voltage signal following a peak of a read signal obtained from the write / read circuit, and the write / read control circuit. After controlling and writing a predetermined test code on the whole track, Uighur characteristic test
Write at the beginning of the divided area, and then
The predetermined test code written is read and its peak
Wherein n regions obtain the corresponding measured m times (m is an integer of 2 or more) to repeatedly the mean value of the output voltage obtained from said detecting circuit for the average of the n region corresponding of the output voltage obtaining a value obtained by correcting the compensation coefficient corresponding to the area for the value, e Bei and a control device for inspecting wiggle characteristic of the magnetic head based on the obtained value, the control device
Is a predetermined test code written on the entire track
Is read for one track and the output voltage for the peak is read.
The average value of pressure and the peak of each of the n regions
The ratio of the average output voltage to
A device for inspecting Uighur characteristics of a magnetic head which is obtained for n areas . 5. The correction coefficient is an arbitrary value for the m measurements.
Corresponding to one time, the predetermined test mark on the entire track
No. is written, and this is read for one round of the track.
The Uighur characteristic test of the magnetic head according to claim 4, wherein
Inspection device.