JP2000339601A - Measuring and inspecting methods of magnetic head track pitch and measurement device and inspection equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for inspecting a magnetic head by itself without incorporating the head into a magnetic recorder to measure peak jitter and the error rate of data signals. SOLUTION: Using a pair of first noise track 21 and a first data track 23 and a pair of first erasing tracks 25 and 26, a first off-track characteristic value is obtained from the N/S curves of all tracks for every position of the first erasing track. Moreover, using a second data track and a pair of second noise tracks, a second off-track characteristic value is obtained from the N/S curves of all tracks for every position of the second noise track. Then, a track pitch is obtained from the position of the portion where the off-track characteristic values are crossed. Then, normal/defective condition of the magnetic head is discriminated from the track pitch.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a track pitch of a magnetic head and a method for inspecting a magnetic head, which can be applied to a composite magnetic head having a write head and a read head provided separately. It relates to an inspection device.

[0002]

2. Description of the Related Art Conventionally, as an example of a composite type magnetic head in which a write head and a read head are provided separately, as shown in FIG.
1 is known. The thin-film magnetic head 52 reads and writes magnetic information by levitating and running on a magnetic recording medium such as a hard disk. The side indicated by 50A in FIG. The side indicated by 50B is the trailing side facing downstream. A rail portion 5 constituting an ABS (air bearing surface) is provided on the bottom surface side of the slider 50 facing the magnetic recording medium.
0a, 50b, 50c are groove-shaped air grooves 51d,
The thin film magnetic core 51 is formed on the end face 50f of the slider 50 on the trailing side 50B.

A thin-film magnetic head 52 shown in this example has a structure shown in FIG.
5 is a composite type magnetic head whose sectional structure is shown in FIG.
A read head 61 composed of a GMR element (thin film element utilizing a giant magnetoresistive effect) or the like on the end face 50f of the slider 51
And an inductive head (write head) 62 are sequentially laminated. The read head 61 of this example includes:
The magnetic signal is read out by detecting the leakage magnetic field from the magnetic recording medium by using the magnetoresistive effect. As shown in FIG. A magnetoresistive multilayer film 55 is provided in a state surrounded by an insulating layer 54 formed of a nonmagnetic material such as alumina, and an upper shield layer 56 is further provided thereon. The coil layer 57 and the upper core layer 58 are provided so as to be surrounded by the insulating layer 59. In this example, the upper shield layer 56 has a structure also serving as the lower core layer of the write head 62. When viewed from the rail surface 50c side of the slider 50, as shown in FIG. 36, the pole tip 58a at the tip of the upper core layer 58 and the upper shield layer (lower core layer)
56 are opposed to each other via an insulating layer 59 so as to form a magnetic gap G for writing.

Meanwhile, in the thin-film magnetic head 52 having the structure shown in FIGS. 34 to 36, the track is narrowed in accordance with the increase in the recording density year by year, and the track width is on the order of microns, and further, on the order of submicrons. Since the size of the pole portion 58a of the write head 62 is extremely narrow because of the miniaturization aiming at the order, the width of the giant magnetoresistive multilayer film 55 of the read head 61 is also extremely narrow. Tend to be. However, even if the magnetic head having the structure shown in FIGS. 34 to 36 is manufactured as designed, the actual write width or read width is determined by assembling each magnetic head into a drive device. It was in a situation where it could not be determined unless it was actually measured.

When the width of the pole tip 58a becomes smaller, the influence of side fringing, in which magnetic flux leaks outward from both side portions of the pole tip 58a as shown by arrows in FIG. Therefore, it was difficult to specify a practical writing width. In particular, the written track, generally, is slightly wider set than the width T ₁ of the pole tip 58a as shown in FIG. 36 in anticipation of the width of the fringing. That is, the pole tip 5
A portion having a slightly wider writing width T ₂ than the width T ₁ of the 8a sets the writing unit 64, with a further erase band 65, 65 in anticipation fringing represented by the width T ₃ on both sides of the width Those having T _{4 correspond} to tracks 66 of the magnetic recording medium.
It is believed that.

Next, FIG. 37 shows the sensitivity distribution of a thin film magnetic head having six types of giant magnetoresistive multilayer films manufactured according to the same specification.
Even if manufactured with the same specifications, the sensitivity is slightly different,
This difference in sensitivity may cause a difference in read width. Therefore, in a thin-film magnetic head using a giant magnetoresistive multilayer film, it is necessary that the write width and read width of each magnetic head can be accurately grasped. Have been.

Therefore, conventionally, there have been provided various means for measuring a track width and a read width when a manufactured thin film magnetic head actually performs magnetic recording on a magnetic recording medium. A widely used first means is that when magnetic recording is performed on a track 66 by a write head as shown in FIG. 38, the erase band 65 on the left side of the track 66 extends from the erase band 65 on the right side. When the output is obtained while the read head H1 is moved in the Y1 direction in the width direction of the track 66, two output positions of 50% of the maximum output obtained at the center of the track 66 are obtained.
This is a means for assuming that the width between the 0% output positions is the write track width.

The second means is known as 74
7 is a measuring means referred to as a test, and comprises a disk-shaped magnetic disk (magnetic recording medium), a rotary drive, a thin-film magnetic head, and an actuator capable of moving the magnetic head to a desired position on the magnetic disk. A random data is recorded on a magnetic recording surface of a magnetic disk using a thin-film magnetic head to be measured using a hard disk drive that is
Of the old information track 200 and the second old information track 200
The old information track 201 is written, and the data track 202 is written so as to further overlap the overlapping portion of the old information tracks 200 and 201, and the position adjustment track 203 is written to the side of the data track 202 while changing the position. In this method, the error rate is measured by scanning the read head 205 according to the writing position of the adjustment track 203. Here, the position adjustment truck 20
Reference numeral 3 denotes a data track adjacent to the data track 202. Therefore, the data track 202 and the position adjustment track 203 have the same write track width T.

Here, the thin film magnetic head 205 to be measured is
Has the same configuration as the one having the read head of the magnetoresistive element and the write head of the inductive head described above with reference to FIGS. 34 to 36, and has a very small track width. The purpose is to measure whether or not the track width including the erase band width is formed according to the design value due to the effect of fringing generated from the tip and the variation in sensitivity of the magnetoresistive effect element. It is.

[0010] In the second means, as shown in FIG. 39A, first, the second old information track 201 is separated from the second old information track 201 on the right side of the second old information track 201, and is separated from the center of the data track 202 by a distance S. The position adjustment track 203 is written at a first position having a center separated by just a distance, and in this state, the read head 205 is scanned in the track width direction as shown in FIG. 39A, and an error rate curve is obtained from noise and a data signal at each position. Is measured. The error rate curve in this case is as shown in FIG. 39B. The state where the center of the read head 205 coincides with the center of the data track 202 is set to “0” on the horizontal axis, and the read head scans at a distance M with respect to the distance M. The axis shows the error rate. However,
The noise signal is a signal from a track other than the data track 202 and the erase band, and the data signal is a signal from the data track 202. Next, position adjustment truck 2
03 to the left of the first position in FIG. 39, for example,
The second partially overlapping the second old information track 201
In this state, the read head 205 is moved to the position shown in FIG.
As shown in FIG. 9, scanning is performed in the track width direction to measure an error rate from noise and a data signal at each position.

Next, the position adjustment track 203 is written at a third position overlapping the erase band on the left side of the second position in FIG. 39, for example, on the right side of the data track 202. As shown in (1), scanning is performed in the track width direction to measure an error rate from noise and a data signal at each position. Next, the position adjustment track 203 is written to the left side of the third position in FIG. 205 to FIG.
As shown in (1), an error rate curve is measured from the noise and the data signal at each position by scanning in the track width direction. Next, the position adjustment track 203 is written to the left side of the fourth position in FIG. 39, for example, at the fifth position further inside the data track 202 beyond the erase band on the right side of the data track 202. The head 205 is scanned in the track width direction as shown in FIG. 39, and the error rate is measured from the noise and data signal at each position.

As described above, a data track can be detected based on the error rate curve for each position from the first position to the fifth position, and a certain error set so as not to cause a malfunction when the track is detected. The distance M over which the read head 205 can move below the rate, that is, the margin distance from the end of the read head to the end of the data track when the center of the data track matches the center of the read head 205, and the off-track performance value F For example, as shown in FIG. 40, the off-track performance value F for each movement position S of the position adjustment track 203 is plotted in a chart, so that the track width and track pitch of the magnetic head can be calculated from the rate of change of the error rate value. You can ask. In other words, the position adjustment track S in a state where the position adjustment track 203 has reached the third position has the optimum track pitch or track width, and is indicated by the point A.
2 was measured only on the left side, but the measurement was similarly performed on the right side.

[0013]

The conventional method of obtaining the write track width by the method described above with reference to FIG. 38 is a method of approximately measuring only the write track width, so that an accurate track width is obtained. There is a problem that cannot be measured. FIG.
The conventional method described above with reference to FIG. 9 and FIG. 40 enables accurate measurement to some extent, but requires a separate read head for reading the write data signal and the noise data signal, and also has an error rate, That is, there is a problem that a circuit for measuring the ratio of signal to noise and a dedicated circuit for measuring peak jitter are required. 39 and 40
In the conventional method described above, it is necessary to mount the magnetic head on the drive device and measure the signal and noise while actually writing and reading the signal. In addition, it is necessary to perform measurement after mounting the magnetic head on the drive device, and it is not possible to detect whether the magnetic head is a good product or a defective product in the state of the magnetic head alone.

The present invention has been made in view of the above circumstances, and it is possible to detect a write track width only by measuring signal strength and noise strength without measuring an error rate, peak jitter, or the like. In addition, the detection method can be easily performed without requiring a special dedicated circuit for the detection, and the track pitch measuring method and the magnetic head measurement method can be evaluated as a single magnetic head without assembling the magnetic head into a drive device. It is an object of the present invention to provide a method, a test method, a measurement device, and an inspection device.

[0015]

According to the present invention, there is provided a method for measuring a track pitch, comprising the steps of: using a magnetic head having a write head and a read head; A pair of adjacent first noise tracks is formed, a first data track is written on these first noise tracks so that both ends in the width direction overlap, and both sides in the width direction of the first data tracks are further written. At a predetermined interval from the first data track.
And the signal strength and the noise strength at each predetermined position are measured using the magnetic head along the width direction of all these tracks, and the ratio between them is calculated (noise / noise). N / S curve indicating the signal / signal ratio, a first off-track characteristic value from the contact point of the N / S curve with respect to the (noise / signal) ratio required for the magnetic head, and the first data The position of the pair of first erase tracks formed with respect to the track is gradually approached to the first data track so that
A first off-track characteristic value is obtained for each position of the erase track, and a second data track is formed on a magnetic recording medium using the magnetic head. A pair of second data tracks is formed on both sides of the second data track. Measuring the signal of the second data track after forming the erase track of the second track, then writing noise on each of the pair of second erase tracks to form a second noise track, and Using the magnetic head, the signal strength and the noise strength at each predetermined position are measured along the width direction, the ratio between them is calculated, and the N / S curve showing the (noise / signal) ratio is obtained. A second off-track characteristic value is obtained from a contact point of the N / S curve with respect to a (noise / signal) ratio required for a head, and the second off-track characteristic value is formed for the second data track. The formation position of the pair of second erase tracks is gradually approached to the second data track to obtain a second off-track characteristic value for each position of the second erase track. The characteristics of the off-track characteristic value at each first erased track position and the characteristics of the second off-track characteristic value at each second erased track position are compared, and the erased track at the point where both off-track characteristic values match is obtained. The track pitch is determined from the position.

Next, in the track pitch measuring method according to the present invention, the distance between the first data track and the pair of first erase tracks is gradually reduced so that the first track at each first erase track position is gradually reduced. When obtaining the off-track characteristic value, the formation position of the first erased track is gradually moved from a position outside the first noise track to a position overlapping the first data track, and the first off-track is formed for each movement position. It is characterized in that a track characteristic value is obtained.

Further, in the track pitch measuring method according to the present invention, the distance between the second data track and the pair of second erase tracks is gradually reduced so that the second off-track for each second erase track position is set. When the track characteristic value is obtained, the second erase track is gradually moved from a position separated from the second data track to a position overlapping with the second data track.

Using the magnetic head, the signal strength and the noise strength at each predetermined position are measured along the width direction of all the tracks, and the ratio between them is calculated (noise / signal).
When the N / S curve indicating the ratio is obtained, the signal strength and the noise strength are separately measured, and the N / S curve is calculated based on the values.
Preferably, a curve is determined.

The magnetic head inspection method of the present invention utilizes the above-described track pitch measurement method, and determines whether the magnetic head is good or defective based on the track pitch measured by any of the above-described track pitch measurement methods. Is determined.

A magnetic head inspection apparatus according to the present invention includes a driving device for supporting and rotating a disk-shaped magnetic recording medium and a magnetic head for inspecting an arbitrary position on a recording surface of the magnetic recording medium. A data track, an erase track, and a noise track at arbitrary positions on a recording surface of the magnetic recording medium by controlling the energization of a write head and a read head provided on the inspection magnetic head. And a recording / reproducing control unit for making it possible to read out the signal of the data track and the noise of the noise track, and use the driving device, the positioning device and the recording / reproducing control unit. An arithmetic unit for calculating the track pitch of the inspection magnetic head by implementing the track pitch measurement method described above is provided.

A magnetic head inspection apparatus according to the present invention includes the configuration of the magnetic head inspection apparatus described above, and further determines whether the inspection magnetic head is good or defective based on the track pitch calculated by the arithmetic unit. It is characterized by including a determination unit for determining.

According to the track pitch measuring method of the present invention, a pair of adjacent reference noise tracks are formed on a magnetic recording medium by using a magnetic head having a write head and a read head. A reference data track is written on the reference noise track so that both ends in the width direction overlap with each other, and a pair of adjustment noise tracks are formed on both sides in the width direction of the reference data track by being separated from the reference data track by a predetermined distance. The magnetic head is scanned from the inside of the reference data track to the outside of the reference data track along the track width direction to measure the signal strength and noise strength of the magnetic head read signal. The amount of movement of the magnetic head until a predetermined (noise / signal) ratio is obtained is obtained, and the reference data track is obtained. The moving position of the magnetic head for each position of the adjustment noise track is obtained by gradually moving the formation position of the adjustment noise track formed with respect to the reference data track, and obtaining the moving amount of the magnetic head for each position of the adjustment noise track. It is characterized in that a track pitch of the magnetic head is obtained from a change state of the moving amount of the magnetic head.

According to the present invention, the position at which the adjustment noise track is formed is set from a position apart from the reference data track in a track width direction of the reference data track to a position overlapping the reference data track. Features. The inspection method according to the present invention is characterized in that the quality of the magnetic head is determined based on the track pitch measured by any one of the methods described above.

A track pitch measuring device according to the present invention comprises a driving device for supporting and rotating a disk-shaped magnetic recording medium and a magnetic head for testing an arbitrary position on a recording surface of the magnetic recording medium. A positioning device for positioning the data track, an erase track, and a noise track on the magnetic recording medium by controlling the energization of a write head and a read head provided on the magnetic head for inspection. 10. A recording / reproducing control unit for making it possible to read out a signal and noise of a noise track, wherein the driving device, the positioning device and the recording / reproducing control unit are used. An arithmetic unit for calculating the track pitch of the inspection magnetic head by implementing the above described track pitch measuring method is provided.

A magnetic head inspection apparatus according to the present invention includes the above-described configuration, and further includes a determination unit for determining whether the inspection magnetic head is good or defective based on the track pitch calculated by the arithmetic unit. Features.

According to the magnetic head inspection method of the present invention, a first reference simple data track is written on a magnetic recording medium using a magnetic head having a write head and a read head, and the first reference simple data track is further written. A pair of first simple erasure tracks are formed on both sides of the track in the track width direction at a predetermined distance from the first reference simple data track, and the magnetic field along the track width direction of the first reference simple data track is formed. The head is scanned to measure the signal strength at each scanning position, and a pair of first reference simple noise tracks are formed on the magnetic recording medium by using the magnetic head. A first reference simple erasure track is written on the first reference simple noise track so as to overlap both ends in the width direction, and the width of the first reference simple erasure track is further written. Forming a pair of first adjusted simple noise tracks on both sides of the first adjusted simple noise track at a predetermined distance from each other, and scanning the magnetic head in the track width direction of the first adjusted simple noise track. The noise intensity at each scanning position is measured, and the ratio between the noise intensity and the signal intensity at each of the separately measured scanning positions is determined for each measurement position, while the ratio of the noise intensity at each measurement position is determined on the magnetic recording medium using the thin-film magnetic head. The second simple reference data track is written in the second simple reference data track, and a second simple erase track is formed on both sides of the second simple reference data track so as to partially overlap with the second simple reference data track. The magnetic head is scanned along the track width direction of the reference simple erasure track to measure the signal strength at each scanning position, and the magnetic head is used to scan each other on a magnetic recording medium. A pair of second reference simple noise tracks adjacent to each other are formed, and a second reference simple erase track is written on the second reference simple noise tracks so as to overlap both ends in the width direction. A pair of second adjusted simple noise tracks partially overlapping the second reference simple erase track are formed on both sides in the width direction of the second reference simple erase track, and the track width of the second adjusted simple noise track is formed. The magnetic head is scanned in the direction to measure the noise intensity at each scanning position, and the ratio of the noise intensity to the signal intensity at each scanning position measured separately is determined for each measurement position, and is determined first. The ratio of the noise intensity to the signal intensity at each scanning position, and the ratio of the noise intensity to the signal intensity at each scanning position determined later are all the noise intensity and signal required for the magnetic head. Than the strength ratio of The magnetic head is determined to be good if it is higher, and is determined to be defective if it is lower.

The inspection device of the present invention is a driving device for supporting and rotating the disk-shaped magnetic recording medium, and positioning the inspection magnetic head at an arbitrary position on the recording surface of the magnetic recording medium. A positioning device and a write head and a read head provided on the inspection magnetic head are energized so that data tracks, erase tracks, and noise tracks can be recorded on the magnetic recording medium, and signals and noise of the data tracks can be recorded. A recording / reproducing control unit for making it possible to read the noise of the track. The method described above is carried out using the driving device, the positioning device and the recording / reproducing control unit, and the noise of the obtained noise is obtained. It is characterized in that a judgment unit for judging good or bad of a magnetic head for inspection based on a ratio of strength to signal strength is provided.

According to the inspection method of the present invention, a simple reference data track is written on a magnetic recording medium using a magnetic head having a write head and a read head, and the simple reference data track is written on both sides in the track width direction of the simple reference data track. A pair of erasing simple tracks is formed at a predetermined interval from the reference data track, and the magnetic head is scanned along the track width direction of the simple reference data track to measure the signal intensity at each scanning position, Using the magnetic head, a pair of simple reference noise tracks that are adjacent to each other are formed on a magnetic recording medium, and a simple reference erase track is written on these simple reference noise tracks so that both ends in the width direction overlap. Further, the simplified reference noise track is separated from the simplified reference noise track by a predetermined distance on both sides in the width direction of the simplified reference erase track. A simple noise track is formed so as to partially overlap the noise track, and the magnetic head is scanned in the track width direction of each track to measure the noise intensity at each scanning position. The ratio of the noise intensity to the signal intensity is determined for each measurement position.If the ratio between the noise intensity and the signal intensity is higher than the ratio between the noise intensity and the signal intensity required for the magnetic head, The head is determined to be good, and if the head is low, it is determined to be defective.

An inspection apparatus according to the present invention is a driving apparatus for supporting and rotating a disk-shaped magnetic recording medium and positioning an inspection magnetic head at an arbitrary position on a recording surface of the magnetic recording medium. A positioning device and a write head and a read head provided on the inspection magnetic head are energized so that data tracks, erase tracks, and noise tracks can be recorded on the magnetic recording medium, and signals and noise of the data tracks can be recorded. A recording / reproducing control unit for making it possible to read the noise of the track. The method described above is carried out using the driving device, the positioning device and the recording / reproducing control unit, and the noise of the obtained noise is obtained. It is characterized in that a judgment unit for judging good or bad of a magnetic head for inspection based on a ratio of strength to signal strength is provided.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment Hereinafter, embodiments of a method for measuring a track pitch of a magnetic head, a method for inspecting a magnetic head, and a measuring apparatus and an inspection apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a measuring device and an inspection device according to a first embodiment of the present invention. The inspection device 1 of this embodiment includes a driving device 3 for rotatably supporting a disk-shaped magnetic disk 2, A rotation control unit 4 for controlling the rotation of the driving device 3 and a support device capable of supporting a thin-film magnetic head 52 whose track pitch is to be measured facing the magnetic recording surface (the surface in FIG. 1) of the magnetic disk 2. 5, a positioning device 6 for moving the thin-film magnetic head 52 via the supporting device 5 to freely move to a desired position on the magnetic recording surface of the magnetic disk 2, and a thin-film magnetic head supported on the supporting device 5. 52, a recording / reproducing amplifier 7 for amplifying the recording signal and the reproducing signal,
A recording / reproduction control unit 8 for controlling recording and reproduction of the thin-film magnetic head 52, an output detection unit 10 for detecting a signal from the recording / reproduction amplifier 7, and the positioning device 6 A positioning control section 11 for controlling the positioning of the thin-film magnetic head 52; a position detecting section 12 for detecting the position of the thin-film magnetic head 52;
N / S described later according to the signal detected from
The calculation unit 13 mainly calculates the S-curve and calculates the off-track characteristic, and the determination unit 14 that determines the quality of the thin-film magnetic head 52 based on the calculation result of the calculation unit 13.

The configuration of the inspection apparatus 1 except for the determination section 14 is different, that is, the driving apparatus 3, the rotation control section 4, the support apparatus 5, the positioning apparatus 6, the recording / reproduction amplifier 7, the recording / reproduction control, and the like. The unit 8, the output detecting unit 10, the positioning control unit 11, the position detecting unit 12, and the calculating unit 13 constitute a track pitch measuring device 15.

Next, the inspection apparatus 1 and the measurement apparatus 1
A first embodiment of a method for measuring the track pitch of the thin-film magnetic head 52 by using No. 5 and judging the quality thereof will be described. 2 to 12 illustrate a first embodiment of a method of measuring a track pitch of a magnetic head according to the present invention. In the first embodiment, for example, FIG.
Read head 61 having a magnetoresistive element such as a GMR element as a read element as shown in FIGS.
Using a thin-film magnetic head 52 having a structure in which a write head (inductive head) 62 and a write head (inductive head) 62 are combined and integrated, a data signal recorded on the recording surface of the disk-shaped magnetic recording medium 2 and a signal recorded around the test track are recorded. This is a method of measuring a track pitch by measuring a ratio of noise signals.

(Measurement of first off-track characteristic value)
In the embodiment, first, as shown in FIG. 2, two first noise tracks 21 and 22 are formed on the magnetic recording surface of the magnetic recording medium 2 by using the thin film magnetic head 52 to be tested.
Are written adjacent to each other at a predetermined interval.
To write these first noise tracks 21 and 22, the magnetic recording medium 2 is rotationally driven by the driving device 3 and the thin-film magnetic head 52 is moved by the positioning device 6 on the formatted magnetic recording surface of the magnetic recording medium 2. The recording / reproduction control unit 8 controls the writing head 62 of the thin-film magnetic head 52 so as to face a desired position, records a desired noise signal on the magnetic recording surface, and forms the first noise track 21. And the thin film magnetic head 5 by the positioning device 6
2 is moved by a predetermined distance in the diameter direction of the magnetic recording medium 2, and then the same noise signal as the previous one is written from the write head 62 to the magnetic recording surface to thereby produce the second noise track 2
1 can be formed. In addition, about these noise tracks 21 and 22, and various tracks mentioned later,
It is not necessary to form it over the entire circumference of the magnetic recording medium 2, but it may be formed at a predetermined length, for example, in one sector or a plurality of sectors.

The interval between the first noise tracks 21 and 22 is set to a width that is clearly smaller than the track width of the thin-film magnetic head 52 to be tested, and is set to an interval that is about a fraction of the track width. The test thin-film magnetic head 52
The shape-accurate track width is not clear without accurate measurement due to manufacturing variations and the like. The pitch is unknown,
The distance between the first noise tracks 21 and 22 used here is about a fraction (eg, 例 え ば) of the track width of the design value of the thin-film magnetic head 52 determined at the time of manufacturing the thin-film magnetic head 52. The interval may be set.

Next, these first noise tracks 21,
22, the center of the magnetic recording surface of the magnetic recording medium 2 on which
That is, the first data track 23 is written so as to straddle the first noise tracks 21 and 22 around the center l ₁ of the interval between the first noise tracks 21 and 22. Then, with respect to such a first data track 23, the thin film magnetic head 52 to be tested in the track width direction is scanned in the direction of arrow a in FIG. Measure. This first data track 23
The measurement result of the signal is indicated by a triangular chevron figure indicated by reference numeral 23a in FIG.

Next, a thin-film magnetic head 52 to be tested so as to be located on the left and right sides of the first data track 23 at a predetermined distance S and partially overlap the first noise tracks 21 and 22. The first erase tracks 25 and 26 from which signals have been erased are formed as shown in FIG.
FIG. 2 shows the planar arrangement of these tracks, and FIG. 3 shows a schematic diagram of the cross-sectional positional relationship of each track. In the first noise track 21, the first erase track 25 and the first
An area sandwiched between the data track 23 and the data track 23 shows the first noise track 21A after partial erasure, and the data track 23 and the erase track 2 in the second noise track 22 are shown.
6 shows the second noise track 22A after partial erasure. Then, the thin-film magnetic head 52 to be tested in the track width direction is scanned in the direction of the arrow a in FIG. 2 for each track shown in FIGS. Measure the strength of

In the signal recording state of each track, the thin film magnetic head 52 applies a magnetic field to the magnetic recording surface of the magnetic recording medium 2 to perform signal recording. The recording signal gradually weakens from the center to the end, and a portion where the recording signal reaches a region where the intensity is lower than the specified intensity means an end in the track width direction. However, here, a signal weaker than the specified strength is recorded further outside the track end, but the signal of this outer portion is a signal that is not determined to be a recording signal. FIG. 4 shows the distribution of signal intensities corresponding to each track in consideration of the above state.

The triangular signal area indicated by the reference numeral 23a in the center of FIG. 4 corresponds to the result of measuring the signal of the first data track 23.
In the signal area of No. 3, since only signals weaker than the prescribed signal output are recorded in the weak signal areas on both the left and right sides, this area is determined to be an area that does not correspond to the first data track 23. In this area, the noise signals of the first noise tracks 21 and 22 which have been recorded previously exist. Note that these first noise tracks 21, 2
2 is partially erased by the first erase tracks 25 and 26, so that the first noise track 21 after the partial erase is located on both sides of the first data track 23.
A, a noise distribution in a triangular shape indicated by reference numeral 21a where the noise from A is measured, and a second noise track 2 after partial erasure.
A triangular noise distribution indicated by reference numeral 22a measured from 2A is obtained. Since the noises of the first noise tracks 21 and 22 before the partial erasure existed before the formation of the erasure tracks 25 and 26, the noise distribution of the noise tracks 21 and 22 before the partial erasure existed. In FIG.
This is indicated by a chain line indicated by a ′ and a chain line indicated by reference numeral 22a ′ for reference.

Next, the horizontal axis (in the track width direction) shown in FIG.
Of the noise (N) and the signal (S) at each position of
The value of N / S is obtained, and an N / S curve as shown in FIG. 5 is obtained. Here, regarding the measurement of the signal strength and the measurement of the noise strength, the thin-film magnetic head 52 does not treat the signal as data, but only measures the signal strength and the noise strength. Since it is not necessary to incorporate 52 into the hard disk drive and it is not necessary to measure it as a signal including the peak jitter and the error rate, it is possible to measure the thin film magnetic head 52 alone. The data track can be detected as a data track required from the specification of the thin-film magnetic head 52 or the target performance of the thin-film magnetic head 52, and the N / S ratio is set so as not to cause a malfunction at the time of track detection. The values are duplicated with respect to the N / S curve as shown by the chain line b in FIG.
The half interval between the two points b ₁ and b ₂ intersecting the / S curve is obtained by calculation as the first off-track characteristic value (OTC value). This calculation can be performed by the calculation unit 13 based on the detection result of the output detection unit 10 in the device configuration shown in FIG.

Next, the first noise tracks 21 and 22 are written into the magnetic recording medium 2 at an arbitrary position on the formatted unused or magnetic recording surface from which the recording has been erased, as in the case shown in FIG. The first data track 23 is written in the same manner as in FIG.
The first erasing tracks 25 and 26 are formed so as to partially overlap the same. Then, as in the previous case, the thin-film magnetic head 52
And the same N as in the case described above with reference to FIG.
/ S curve, and a first off-track characteristic value (OTC value) is calculated from the N / S curve.

In the above operation, the first erase track 2
The distance between the first and second data tracks 23 and 25 is repeatedly measured while changing the distance between the first and second data tracks 23 by a specified amount.
The first off-track characteristic value for each of the 26 positions S is obtained, and the result is plotted on the graph shown in FIG. The interval to be changed here is several μ inches, for example, 2 μ inches (= 0.
05 μm). As a result, the OTC for each first erase track position as shown by reference numeral 9 in FIG.
A first off-track characteristic curve indicating the value can be obtained. In the graph shown in FIG. 5, the horizontal axis indicates the scanning position by the thin-film magnetic head 52, so the unit indicates a length such as μ inch or μm, and the vertical axis indicates a numerical value indicating the ratio. In FIG. 6, since the horizontal axis indicates the position of the first erase track, the unit indicates a length such as μ inch or μm. Here, the erase track position S is a distance from the center of the first data track to the center of each first erase track.

The positions of the tracks shown in FIGS. 2 to 4 are one example, and the first erase tracks 25 and 26 are directed to the first data track 23 on both sides of the first data track 23. As described above, the first off-track characteristic value is calculated at each position while gradually approaching the first noise tracks 21 and 22 when the first erase tracks 25 and 26 are approached. From the position where the first erase tracks 25 and 26 do not contact,
Of course, the data track 23 may be approached. It is also desirable to move the first erase tracks 25 and 26 until they completely overlap the first data track 23 to measure the first off-track characteristic. Furthermore, the first
It is sufficient that the interval between the noise tracks 21 and 22 is smaller than the width of the first data track 23, so that the interval may be slightly wider than the interval shown in FIG.

(Measurement of second off-track characteristic value)
7, the magnetic recording medium 2 is formatted as shown in FIG.
Only other unused magnetic recording surfaces or erased magnetic recordings
Using the thin-film magnetic head 52 for testing, the center l
_FourAnd a second data track 30 is formed along
Deletes adjacent data positions that are separated by a predetermined interval S
The second erase tracks 31 and 32 are _Five, L₆Along the shape
And the second data track 3 after erasing the adjacent data position
0 is transmitted to the thin-film magnetic head 52 in the same manner as described above.
Scan in the track width direction to determine the signal strength at each scanning position.
Measure. FIG. 7 shows the state of the second data track 3
0, the second erase tracks 31 and 32 having a predetermined width
Indicates a duplicated state. Then as shown in FIG.
The thin-film magnetic layer is located at the position of the second erase tracks 31 and 32 earlier.
The noise signal is overwritten by the head 52 and the second
Noise tracks 33 and 34 are formed. Figure 9 shows these
Shows the position of the recording signal. Then, the thin-film magnetic head 52
Is scanned in the direction of arrow c in FIG.
The noise intensity is measured for each of the scanning positions 3 and 34.

FIG. 10 shows the measurement results of these signals and the measurement results of noise. In FIG. 10, a triangle indicated by reference numeral 30a at the center indicates a signal measurement result of the second data track 30, and a triangle indicated by reference numeral 33a on both sides indicates a noise measurement result of the second noise track 33.
The triangle indicated by indicates the noise measurement result of the second noise track 34. Note that, in the measurement signal distribution of the second data track 30, only signals weaker than the prescribed signal output are recorded in the weak signal area on both the left and right sides, so this area does not correspond to the second data track 30. The area is determined. Then, in FIG.
The measurement noise of the noise tracks 33 and 34 exists.
Since the signal of the second data track 30 has been partially erased by forming the erase tracks 31 and 32 on both sides first, the signal before the erase is represented by a triangular chain line 30 'in FIG. This is shown schematically.

Then, similarly to the case described above with reference to FIGS. 5 and 6, the thin film magnetic head 52 is scanned in the track width direction in FIG. The ratio of S) to the strength, that is, the value of N / S is obtained, and the N / S curve as shown in FIG. 11 is obtained. Then, the value of the above-mentioned N / S ratio required from the specifications of the inspection thin-film magnetic head 52 or from the target performance of the thin-film magnetic head 52 is converted into an N / S curve as shown by a chain line d in FIG. On the other hand, a half interval between two points d ₁ and d ₂ intersecting the N / S curve is calculated as a second off-track characteristic value (OTC value). This calculation can be performed by the calculation unit 13 based on the detection result of the output detection unit 10 in the configuration shown in FIG.

In the above processing, the distance between the second noise tracks 33 and 34 and the second data track 30 is repeatedly measured while the distance between the second data tracks 30 is changed by a specified amount.
The second off-track characteristic value for each of the positions S at positions 3 and 34 is obtained, and the result is plotted on a graph as shown in FIG. As a result, the off-track characteristic value (OTC
) Can be obtained. And by drawing a first off-track characteristic curve 9 illustrating the OTC value previously determined as shown in FIG. 6 on the graph of FIG. 12, the intersection e ₁ between the second off-track characteristic curve 15 is obtained Therefore, the erase track position at the position of the intersection e ₁ has been detected as the track pitch e of the thin-film magnetic head 52.

If the track pitch e is obtained by the above-described method, the signal strength and the noise strength are separately measured using the thin-film magnetic head 52, and the first and second measurement results are calculated based on the separate measurement results. The first and second off-track characteristic values are obtained, and the track pitch e can be obtained from the first and second off-track characteristic values. In the method described above, the measurement of the signal strength and the measurement of the noise strength performed separately are general signal noise measurements that can be measured by the thin film magnetic head 52 alone. Can be measured by the thin-film magnetic head 52 alone without recording the actual recording signal, peak jitter, etc. by mounting the thin-film magnetic head 52 on the hard disk drive, so that the track pitch e of the thin-film magnetic head 52 can be measured on the hard disk drive. Before you can do that.

Further, since the track pitch e of the thin-film magnetic head 52 can be measured before mounting it on the hard disk drive, when the track pitch e of the thin-film magnetic head 52 is measured, the measured value becomes the allowable range of the specification and the design value. When the track pitch e is out of the permissible range of specifications and design values, the inspected thin-film magnetic head 52 can be identified as a non-defective product. It can be determined as defective. This determination is performed in the configuration shown in FIG.
In advance, an allowable range obtained from the specifications and design values of the thin-film magnetic head 52 is input in advance, and the determination is made by the determination unit 14 based on the value of the track pitch e measured by the calculation unit 13 so as to be easily implemented. Can be. Therefore, the track pitch e is measured by the method described above using the configuration shown in FIG. 1 and the value of the track pitch e is determined by the determination unit 14 so that the thin-film magnetic head 52 can be mounted on the hard disk drive before mounting. Can be inspected.

The position of each track shown in FIGS. 7 to 10 is one example, and the second noise tracks 33, 3
4 is gradually approached to the second data track 30 on both sides of the second data track 30 and the second off-track characteristic value is calculated at each position as described above. Noise tracks 33, 34
When the (in other words, the second erase tracks 31, 32) approach the second data track 30, the second noise tracks 33, 34 gradually move from the position not in contact with the second data track 30 to the second data track 30. Needless to say, the track 30 may be approached. Further, the second off-track characteristics may be measured by moving the second erase tracks 33 and 34 until they completely overlap the second data track 30.

[Second Embodiment] A method of measuring a track pitch of a magnetic head, a method of inspecting a magnetic head, and a second embodiment of a measuring apparatus and an inspection apparatus according to the present invention will be described below with reference to the drawings. FIG. 13 is a configuration diagram of a track pitch measuring device and a thin-film magnetic head inspection device according to a second embodiment of the present invention. The inspection device 45 of this embodiment is for supporting the disk-shaped magnetic disk 2 rotatably. Drive 3
A rotation control unit 4 for controlling the rotation of the driving device 3,
Thin-film magnetic head 52 for measuring track pitch
And a supporting device 5 capable of supporting the magnetic recording surface (front surface) of the magnetic disk 2 in opposition to the magnetic recording surface of the magnetic disk 2, and moving the thin-film magnetic head 52 via the supporting device 5 to set an arbitrary position on the magnetic recording surface of the magnetic disk 2. A positioning device 6 that can be freely moved;
A recording / reproducing amplifier 7 for amplifying a recording signal and a reproducing signal of the thin-film magnetic head 52 supported by the supporting device 5,
A recording / reproduction control unit 8 connected to the recording / reproduction amplifier 7 for controlling recording / reproduction of the thin-film magnetic head 52; and an output detection unit 10 for detecting a signal from the recording / reproduction amplifier 7
The thin film magnetic head 5 is operated by operating the positioning device 6.
2, a position control unit 41 for detecting the position of the thin-film magnetic head 52, and an N / S curve described later according to the signal and noise value detected from the output detection unit 10. And a determination unit 44 for determining the quality of the thin-film magnetic head 52 based on the calculation result of the calculation unit 43.
It is composed mainly of.

In the configuration of the inspection device 45,
According to the configuration of the part excluding the determination unit 44, that is, the driving device 3, the rotation control unit 4, the support device 5, the positioning device 6, the recording / reproducing amplifier 7, the recording / reproducing control unit 8, the output detecting unit 10, the positioning control unit 41 The track pitch measuring device 46 includes the position detecting unit 42 and the calculating unit 43.

Next, a method of measuring the track pitch of the thin-film magnetic head 52 using the measuring device 46 having the above-described configuration will be described. 14 to 19 illustrate a second embodiment of the method of measuring the track pitch of a magnetic head according to the present invention. In the second embodiment, for example, the method shown in FIGS. A thin-film magnetic head 52 having a structure in which a read head 61 having a magneto-resistance effect element such as a GMR element as a read element as a read element and a write head (inductive head) 62 is combined and used as a structure,
This is a method of measuring a track pitch by measuring a ratio of a data signal recorded on a test track on a magnetic recording surface of the disk-shaped magnetic recording medium 2 to a noise signal recorded around the test track.

In the second embodiment, first, FIG.
As shown in FIG. 4, the core width (read track width) of the read head is set to T ₁ , the write section 64 having the write width T ₂ is set, and the erase bands 65, 65 are placed on both sides of the write section 64. Those provided are defined as trucks 66. A method of measuring a magnetic track using a plurality of noise tracks and data tracks using such a track 66 as described below with reference to FIGS.

First, the thin-film magnetic head 5 to be tested
As shown in FIG. 15, two reference noise tracks 80 and 81 are written adjacent to each other on the magnetic recording surface of the magnetic recording medium 2 which has been formatted and is unused or has been erased, with a predetermined interval therebetween as shown in FIG. . To write these reference noise tracks 80 and 81, the magnetic recording medium 2 is rotationally driven by the driving device 3 and the thin-film magnetic head 52 is magnetically recorded by the positioning device 6 in the same manner as in the first embodiment. Facing an arbitrary position on the magnetic recording surface of the medium 2,
The recording / reproduction control unit 8 controls energization of the write head 62 of the thin-film magnetic head 52 to record a desired noise signal on the magnetic recording surface to form a first noise track 80,
After that, the thin film magnetic head 52 is moved by a predetermined distance in the diameter direction of the magnetic recording medium 2 by the positioning device 6, and then the same noise signal as the previous one is written from the write head 62 to the magnetic recording surface to thereby obtain the reference noise track. 81 can be formed. Note that these reference noise tracks 80 and 81 and various tracks described later need not be formed on the entire circumference of the recording surface of the magnetic recording medium 2 and have a predetermined length, for example, one sector or a plurality of sectors. May be formed.

Next, a reference data track 85 is written so as to straddle the reference noise tracks 80 and 81 at the center of the area where the reference noise tracks 80 and 81 are formed, and then adjusted to a position outside the reference noise tracks 80 and 81. The noise tracks 82 and 83 are written. The erase bands 80a, 81a, 82a, 83a, 85a are respectively provided on both sides of the noise tracks 80, 81, 82, 83, 85.
a is formed.

In FIG. 15, the read head 61 of the thin film magnetic head 52 made of the magnetoresistive effect multilayer film is scanned from the center position inside the reference data track 85 in the track width direction to obtain a predetermined noise / signal ratio (N / S). The movement amount T1 of the thin-film magnetic head 52 until the ratio (ratio) is reached is measured. Here, if the N / S ratio is set to 1: 5, the read head 6
It is assumed that the thin-film magnetic head 52 scans until the ratio of noise and signal detected by 1 becomes 1: 5. This ratio may be any ratio of 1: 5 or 1:10.

Next, as shown in FIGS. 15 to 18, the adjustment noise tracks 82 and 83 are gradually
5, the writing is performed by moving in the direction of approaching, and the scanning of the reading head 61 is repeated for each predetermined position. FIG. 19 shows the result.

First, the scanning of the read head 61 when the adjustment noise tracks 82 and 83 located on both sides of the reference data track 85 are sufficiently separated from the reference data track 85 will be described with reference to FIG. In the state where the signal strength is read from the reference data track 85, the position where the signal is strongest and the noise is small is the center of the data track 85 in view of the signal-to-noise ratio.
From this center position, the read head 61 (specifically, the magnetoresistive multilayer film 55) is moved to the right side in FIG. 15 for scanning. If it is defined that scanning is performed until the ratio of noise (N) to signal (S), N: S is, for example, 1: 5,
Assuming that the read head 61 moves to the right in FIG. 15 as indicated by the arrow and N: S becomes 1: 5 at the position indicated by reference numeral 86a in FIG. 15, the scanning ends at that point, and the moving distance at this time Is T1. The read head 61 picks up noise for the first time because the end of the read head 61
Is the case where the vehicle has passed the erase band 85a and reached the position of the reference noise track 81.

The moving distance T1 is equal to the reference data track 8
As shown in FIG. 16, the adjustment noise track 83 approaches the erase band 8 of the reference data track 85.
5a and erase band 83a of reference noise track 83
Keeps a constant value until the noise of the reference noise track 81 is hidden. Therefore, in FIG. 19, this means a region where the read head movement amount where the point A is located is a fixed value, and the distance between the reference data track 85 and the adjustment noise track 83 at the point A is P1.

Next, the distance between the adjustment noise tracks 82 and 83 and the reference data track 85 is reduced, and as shown in FIG.
When the ends of the adjustment noise tracks 82 and 83 coincide with the ends of the erase bands 82a and 83a, the read head 61 reaches the adjustment noise track 83 beyond the erase band 83a of the adjustment noise track 83. Only after that, the noise of the adjustment noise track 83 starts to be detected and moves to the position 86b in FIG. 16 where N: S becomes 1: 5. Therefore, the movement amount T2 of the read head 86 in this position 86b is the maximum. Becomes This movement amount T2 corresponds to the point B in FIG. 19, and the distance between the adjustment data track 85 and the adjustment noise track 83 in this case is P2.

Subsequently, when the adjusted noise tracks 82 and 83 are further moved in a direction approaching each other and recorded, the erase bands 82a,
As shown in FIG. 17, 83a completely overlaps the erase bands 85a, 85a of the reference data track 85. At this time, the read head 61 is scanned and N: S becomes 1:
5, the reading head 61 is moved to
7 shows the movement amount T3 up to the position indicated by reference numeral 86c. This movement amount T3 corresponds to the point C in FIG. 19, and the interval between the reference data rack 85 and the adjustment noise track 83 in this case is P3.

Further, when the adjustment noise tracks 82 and 83 are moved in a direction to approach each other, the adjustment noise tracks 82 and 83 are moved to the reference data track 8 as shown in FIG.
5, and when the read head 86 is scanned at this time, the read head 86 becomes N: S =
The distance traveled until 1: 5 is the distance indicated by T4. In that state, it corresponds to point D in FIG. 19. In this case, the reference data track 85 and the adjustment noise track 8
The distance of 3 is P4. Adjust noise tracks 82, 83
When the mutual distance becomes short, the amount of movement of the read head 61 gradually decreases, so that the amount of movement of the read head approaches zero as shown in FIG.

As described above, when the amount of movement of the read head 61 is plotted on the vertical axis and the distance between the reference data track 85 and the adjustment noise track 83 is plotted on the horizontal axis, the relationship shown in FIG. 19 is obtained, and the diagram shown in FIG. Since the distance P3 between the reference data track 85 and the reference noise track 83 at the point B showing the peak at the point B is half the track width of the reference data track 85 including the erase bands 85a, 85a, this P3 value is set to 2 By doubling, the track pitch can be obtained.

If the track pitch of the thin-film magnetic head 52 is obtained by the above-described method, the ratio of the signal intensity and the noise intensity obtained by scanning from inside the reference data track 85 using the thin-film magnetic head 52 is determined. The track pitch can be obtained from the transition of the movement amount of the read head 61 until the ratio becomes a constant based on the ratio. In this method, the signal-to-noise ratio need only be determined to determine the amount of movement of the read head 61.
This is a general signal noise measurement that can be measured by the thin film magnetic head 52 alone, and can be measured by the thin film magnetic head 52 alone without mounting the thin film magnetic head 52 on a hard disk drive and recording the actual recording signal, peak jitter, etc. So
The measurement of the track pitch of the thin-film magnetic head 52 can be performed before mounting on the hard disk drive.

Further, since the track pitch of the thin-film magnetic head 52 can be measured before mounting it on the hard disk drive, when the track pitch of the thin-film magnetic head 52 is measured, the measured value falls within the permissible range of specifications and design values. If there is, the thin film magnetic head 52 can be determined as a non-defective product. Conversely, if the measurement location of the track pitch e is out of the permissible range of the specification or design value, the inspected thin film magnetic head 52 is regarded as a defective product. Can be determined.
In this configuration, in the configuration shown in FIG. 13, an allowable range obtained from the specifications and design values of the thin-film magnetic head 52 is input to the determination unit 44 in advance, and based on the track pitch value measured by the calculation unit 43, The determination can be easily made by the determination unit 44. Accordingly, the track pitch is measured by the method described above using the configuration shown in FIG. 13 and the value of the track pitch is determined by the determination unit 44, whereby the thin-film magnetic head 52 is inspected before being mounted on the hard disk drive. be able to.

[Third Embodiment] A third embodiment of a magnetic head inspection method and an inspection apparatus according to the present invention will be described below with reference to the drawings. FIG. 20 is a configuration diagram of a thin-film magnetic head inspection apparatus according to a third embodiment of the present invention. The inspection apparatus 95 of this embodiment includes a driving device 3 for rotatably supporting the disk-shaped magnetic disk 2, A rotation control unit 4 for controlling the rotation of the driving device 3, a support device 5 capable of supporting a thin-film magnetic head 52 whose track pitch is to be measured to face the magnetic recording surface (surface) of the magnetic disk 2, and A positioning device 6 for moving the thin-film magnetic head 52 via the support device 5 to freely move to a desired position on the magnetic recording surface of the magnetic disk 2, and a recording device for the thin-film magnetic head 52 supported by the support device 5. A recording / reproducing amplifier 7 for amplifying a signal and a reproducing signal; a recording / reproducing control unit 8 connected to the recording / reproducing amplifier 7 for controlling recording / reproducing of the thin-film magnetic head 52; An output detection unit 10 for detecting a signal from the thin film magnetic head 52; a position control unit 91 for controlling the positioning of the thin film magnetic head 52 by operating the positioning device 6; and a position detection unit 92 for detecting the position of the thin film magnetic head 52. A calculation unit 93 for calculating an N / S curve, which will be described later, according to the signal detected from the output detection unit 10 and the value of noise, and determining whether the thin-film magnetic head 52 is good or bad based on the calculation result of the calculation unit 93. And a determination unit 94 that performs the determination.

Next, a method of inspecting the thin-film magnetic head 52 using the inspection apparatus 95 having the above-described configuration will be described. FIGS. 21 to 26 are for explaining the third embodiment of the present invention. In the third embodiment, for example, FIG.
Read head 61 having a magnetoresistive element such as a GMR element as a read element as shown in FIGS.
A data signal recorded on a test track on a magnetic recording surface of a disk-shaped magnetic recording medium 2 and a test track thereof using a thin-film magnetic head 52 having a structure in which a write head (inductive head) 62 and a write head 62 are combined and integrated. A noise signal recorded on the periphery, a noise track formed on a test track, and an erase track formed on a part of the noise track separated from or overlapped with the noise track and a noise track formed on a peripheral track are measured. This is a method for inspecting the magnetic head 52.

In the third embodiment, the inspection of the thin-film magnetic head 52 to be measured is performed by a first step inspection described below and a second step inspection described later. "Inspection of First Step" First, a first reference simple data track 110 and first simple erase tracks 111 on both sides of the first reference simple data track 110 as shown in FIG. The data is written on a formatted unused or erased magnetic recording surface of the magnetic recording medium 2 with a space therebetween. In this embodiment, erase bands 110a and 111a are formed on both sides of each track 110 and 111 as in the previous embodiment. To write the first reference simple data track 110 and the first simple erase tracks 111, 111, the magnetic recording medium 2 is rotationally driven by the driving device 3 as in the case of the first embodiment, The thin-film magnetic head 52 is made to face an arbitrary position on the magnetic recording surface of the magnetic recording medium 2 by the positioning device 6, and the recording / reproduction control unit 8 controls the energization of the write head 62 of the thin-film magnetic head 52 to generate a desired signal. A first reference simple data track 110 is formed by recording on the recording surface, and after the thin-film magnetic head 52 is moved by a predetermined distance in the diameter direction of the magnetic recording medium 2 by the positioning device 6, the write head 62 By erasing the signal on the magnetic recording surface, the first simple erase tracks 111, 111 can be formed. The first reference simple data track 110, the erasure tracks 111 and 111, and various tracks to be described later need not be formed on the entire circumference of the recording surface of the magnetic recording medium 2, but have a predetermined length, for example. One sector or a plurality of sectors may be formed. Also, the point that erase bands 113a are formed on both sides of the reference simple noise track 113 is the same as in the case of each noise track of the above embodiment.

Then, these first reference simple tracks 1
10 and a pair of first simple erase tracks 111, each track 11
The thin film magnetic head 52 to be tested in the width direction of 1, 110 and 111 is scanned in the direction of arrow f in FIG. 21 to measure the signal strength at each position in the track width direction. This signal measurement result is shown by a triangular figure shown by reference numeral 112 in FIG.

Next, as shown in FIG. 22, two reference simple noise tracks 113 are made adjacent to each other at another position on the magnetic recording surface of the magnetic recording medium 2 by using the thin-film magnetic head 52 so as to be separated from each other by a predetermined distance. And write. In order to write these reference simple noise tracks 113, 113, FIG.
The magnetic recording medium 2 is driven to rotate by the driving device 3 shown in FIG. 1, and the thin-film magnetic head 52 is made to face an arbitrary position on the formatted magnetic recording surface of the magnetic recording medium 2 by the positioning device 6. A desired noise signal is recorded on the magnetic recording surface by controlling the energization of the write head 62 of the thin-film magnetic head 52 to form one reference simple noise track 113, and thereafter the thin-film magnetic head 52 is magnetically recorded by the positioning device 6. After moving the medium 2 by a predetermined distance in the diameter direction, the second reference simple track 113 can be formed by writing the same noise signal from the write head 62 to the magnetic recording surface. In addition,
The reference simple noise track 113 and various tracks described later need not be formed on the entire circumference of the magnetic recording medium 2, but may be formed in a predetermined length, for example, in one sector or a plurality of sectors. good.

The reference simple noise tracks 113 and 11
The interval of 3 is set to a width clearly smaller than the track width of the thin film magnetic head 52 to be tested, for example, an interval of about a fraction of the track width. In the test thin-film magnetic head 52, the exact track width in terms of shape has variations at the time of manufacture, etc., and it is unknown without accurate measurement. Fringing due to magnetic flux leakage from the write head is not known. Although the added magnetic track width and track pitch are unknown, the reference simple noise track 11 used here is unknown.
The interval between 3 and 113 may be set to an interval which is about a fraction (for example, 1/2) of the track width of the design value of the thin-film magnetic head 52 determined at the time of manufacturing the thin-film magnetic head 52.

Next, these reference simple noise tracks 11
The reference simple noise track 11 is centered on the center of the magnetic recording surface of the magnetic recording medium 2 on which the reference noise tracks 3 and 113 are formed, that is, the center of the interval between the reference simple noise tracks 113 and 113.
3 and 113 so that the reference simple erase track 11
5 is written by the thin-film magnetic head 52. Subsequently, a noise signal is written by using a thin-film magnetic head 52 to be tested at predetermined left and right sides of the reference simple noise tracks 113, 113, and the adjusted simple noise track 11 is written.
6, 116 are formed as shown in FIG. Each of the tracks 113, 115, and 116 formed as described above has the same erase band 113 as that of the previous embodiment.
a, 115a and 116a are formed. For each track shown in FIG. 22, the thin film magnetic head 52 to be tested in the track width direction is scanned in the direction of arrow g in FIG. 22 to measure the noise intensity at each position in each track width direction. Is measured.

In the signal recording state of each track, since the thin-film magnetic head 52 performs signal recording by applying a magnetic field to the magnetic recording surface of the magnetic recording medium 2, the central portion of each track has the most recording signal. The recording signal gradually weakens from the center to the end, and a portion where the recording signal reaches a region where the intensity is lower than the specified intensity means an end in the track width direction. However, here, a signal weaker than the specified strength is recorded further outside the track end, but the signal of this outer portion is a signal that is not determined to be a recording signal. FIG. 22 shows the distribution of the signal intensity corresponding to each track in consideration of the above state.

In FIG. 22, the area indicated by reference numeral 117 in the center corresponds to the area where the signal is erased by the reference simple erasure track 115. In the signal area of the reference simple noise tracks 113 on both sides of this area, Since a part of the signals of the reference simple noise tracks 113 and 113 are erased by the reference simple erase track 115, the reference simple noise tracks 113 and 11 after partial erasure are used.
The noise intensity distribution of No. 3 is a triangular noise intensity indicated by reference numerals 118 and 118. In FIG. 22, the noise intensity of the reference simple track 113 before forming the reference simple erasure track 115 is indicated by a chain line indicated by reference numeral 119. The noise intensity of the simple adjustment noise track 116 has a triangular distribution indicated by reference numeral 120. Further, FIG.
By scanning the thin-film magnetic head 52 in the horizontal direction shown in FIG. 2, that is, in the track width direction, the noise intensity at each track position is measured.

Next, the noise (N) for each measurement position obtained at the time of the noise measurement described with reference to FIG. 22 and the signal (N) obtained at the time of the signal measurement described with reference to FIG. The ratio with the signal (S) at each measurement position, that is, the value of the N / S ratio was determined, and FIG.
An N / S curve as shown in FIG. Here, regarding the measurement of the signal strength and the measurement of the noise strength described above, the thin-film magnetic head 52 does not treat the signal as data, but only needs to measure it as the signal strength and the noise strength. Therefore, it is not necessary to incorporate the magnetic head 52 into the hard disk drive, and it is not necessary to measure the signal including the peak jitter and the error rate. Therefore, the measurement can be performed by the thin film magnetic head 52 alone.

From the specification of the thin-film magnetic head 52,
Alternatively, the value of the N / S ratio required from the target performance of the thin-film magnetic head 52 is described with respect to the N / S curve in FIG. 23, and corresponds to the width of the N / S curve in the case of this N / S ratio. If the value of the track pitch falls within the range of the specifications required for the thin-film magnetic head 52, the thin-film magnetic head 52 is regarded as a primary inspection-passed product, and the range of the specification is determined. If the track pitch is out of the range, the thin-film magnetic head 52 is determined to be defective. The calculation of these N / S curves and the determination of non-defective / defective products from the specifications can be performed by the calculation unit 93 and the determination unit 94.

[Second Step] Next, using the thin film magnetic head 52 to be tested, as shown in FIG.
Is written on the formatted unused or erased magnetic recording surface of the magnetic recording medium 2, and then the second simple erase tracks 124 are written on both sides thereof. In writing the second reference simple erasure track 124, in other words, one end of the second simple erasure track 124 and the one end of the second reference simple data track 123 overlap, in other words. The erase band 123a of the second reference simple data track 123 and the erase band 124a of the second simple erase track 124 are recorded so as to partially overlap.

These second reference simple data tracks 1
23 and the second simple erase tracks 124, 124, the magnetic recording medium 2 is rotationally driven by the driving device 3 and the positioning device 6 is written in the same manner as in the first embodiment.
The thin-film magnetic head 52 is opposed to an arbitrary position on the magnetic recording surface of the magnetic recording medium 2 by the control of the recording / reproduction control unit 8 to control the write head 62 of the thin-film magnetic head 52 to apply a desired signal to the magnetic recording surface. After the recording, the second reference simple data track 123 is formed, and then the thin-film magnetic head 52 is moved by the positioning device 6 in the diameter direction of the magnetic recording medium 2 by a predetermined distance. Erase band 123a of the standard simple truck 123
And the erase band 12 of the second simple erase track 124
What is necessary is just to write so that 4a may partially overlap. Here, the exact width of the erase bands 123a and 124a is unknown, but the second reference simple data track 1 is set so that the erase bands 123a and 124a partially overlap each other.
Recording the 23 and the second simple erase track 124 can be easily implemented.

The second reference simple data track 123, the second simple erase track 124, and various tracks to be described later need not be formed on the entire circumference of the recording surface of the magnetic recording medium 2; , For example, in one sector or a plurality of sectors.

Next, using the thin-film magnetic head 52, two second simple reference noise tracks 130 are placed adjacent to each other at other positions on the magnetic recording surface of the magnetic recording medium 2 as shown in FIG. Write in the specified interval. In order to write the second reference simple noise tracks 130, 130, the magnetic recording medium 2 is driven to rotate by the driving device 3 shown in FIG. The recording / reproduction control unit 8 controls the writing head 62 of the thin-film magnetic head 52 to energize the write head 62 so as to record a desired noise signal on the magnetic recording surface, and record the desired noise signal on the magnetic recording surface. After the reference simple noise track 130 is formed and the thin-film magnetic head 52 is moved by the positioning device 6 in the diameter direction of the magnetic recording medium 2 by a predetermined distance, the same noise signal as the previous one is magnetically transmitted from the write head 62. By writing on the recording surface, the second second reference simple noise track 130 is written.
Can be formed. The second reference simple noise track 130 and various tracks described later need not be formed on the entire circumference of the magnetic recording medium 2.
It may be formed in a predetermined length, for example, in one sector or a plurality of sectors.

The reference simple noise tracks 130 and 13
The interval of 0 is set to a width clearly smaller than the track width of the thin-film magnetic head 52 to be tested, for example, an interval of about a fraction of the track width. In the test thin-film magnetic head 52, the exact track width in terms of shape has variations at the time of manufacture, etc., and it is unknown without accurate measurement. Fringing due to magnetic flux leakage from the write head is not known. Although the added magnetic track width and track pitch are unknown, the distance between the second reference simple noise tracks 130, 130 used here is determined by the design of the thin-film magnetic head 52 determined at the time of manufacturing the thin-film magnetic head 52. The interval may be set to about a fraction (for example, 1/2) of the track width of the value.

Next, the center of the magnetic recording surface of the magnetic recording medium 2 on which the second reference simple noise tracks 130 and 130 are formed, that is, the second reference simple noise track 13
The second reference simple erase track 131 is written so as to straddle the second reference simple noise tracks 130 and 130 around the center of the interval between 0 and 130. Then, the second
The noise signals are written on the left and right sides of the reference simple noise track 131 using the thin-film magnetic head 52 to form the second adjustment simple noise tracks 133 and 133 as shown in FIG. Then, for each track shown in FIG. 25, the thin film magnetic head 52 to be tested in the width direction of the track is scanned in the direction of arrow i in FIG. Is measured.

In the noise signal recording state of each track, since the thin-film magnetic head 52 applies a magnetic field to the magnetic recording surface of the magnetic recording medium 2 to perform signal recording, the center of each track is most recorded. It becomes a strong part of the signal, the recording signal gradually weakens from the center to the end,
The part where the recording signal reaches the area where the intensity is lower than the specified strength means the end of the track in the width direction. However, here, a noise signal weaker than the specified strength is recorded further outside the end of the track, but the noise signal in the outer portion is a signal that is not determined as a recording signal. FIG. 25 shows the distribution of the intensity of the noise signal corresponding to each track in consideration of the above state.

In FIG. 25, the triangular noise signal distribution areas indicated by the left and right symbols 135 are obtained from the second simplified noise tracks 133 and 133. continue,
The thin film magnetic head 52 is scanned in the lateral direction shown in FIG. 25, that is, in the track width direction as indicated by an arrow i, and the noise intensity at each track position is measured.

Next, the noise (N) at each measurement position obtained in the noise measurement described with reference to FIG. 25 and the signal (N) obtained in the signal measurement described with reference to FIG. The ratio with the signal (S) at each measurement position, that is, the value of the N / S ratio was determined, and FIG.
An N / S curve as shown in FIG. Here, regarding the measurement of the signal strength and the measurement of the noise strength described above, the thin-film magnetic head 52 does not treat the signal as data, but only needs to measure it as the signal strength and the noise strength. Therefore, it is not necessary to incorporate the magnetic head 52 into the hard disk drive, and it is not necessary to measure the signal including the peak jitter and the error rate. Therefore, the measurement can be performed by the thin film magnetic head 52 alone.

From the specification of the thin-film magnetic head 52,
Alternatively, the value of the N / S ratio required from the target performance of the thin-film magnetic head 52 is described with respect to the N / S curve in FIG. 26, and corresponds to the width of the N / S curve in the case of this N / S ratio. If the value of the track pitch falls within the range of specifications required for the thin-film magnetic head 52, the thin-film magnetic head 52 is regarded as a product that has passed the secondary inspection, and the range of the specification If the track pitch is out of the range, the thin-film magnetic head 52 is determined to be defective. The calculation of these N / S curves and the determination of non-defective / defective products from the specifications can be performed by the calculation unit 93 and the determination unit 94.

As described above, if the intervals corresponding to the track pitches of the N / S curves respectively obtained in the first step and the second step are within the range of the specification, the thin film magnetic head used for the measurement is used. The determination unit 94 determines 52 as non-defective and ends the inspection. When the track pitch deviates from the range allowed in the specification in one of the first step and the second step, the determination unit 94 determines that the thin-film magnetic head 52 used for the measurement is defective. . Both the signal strength and the noise signal strength measured in the first step and the second step are ordinary signal noise measurements that can be performed by the thin film magnetic head 52 alone. That is, in order to inspect the thin-film magnetic head in the inspection method of the third embodiment, the signal is not treated as data, but only the signal intensity and the noise intensity need to be measured. There is no need to incorporate the thin-film magnetic head 52 into a hard disk drive device, and it is not necessary to measure the signal including the peak jitter and the error rate.

Fourth Embodiment A fourth embodiment of the method and apparatus for inspecting a magnetic head according to the present invention will be described below with reference to the drawings. FIG. 27 is a configuration diagram of a thin-film magnetic head inspection apparatus according to a fourth embodiment of the present invention. The inspection apparatus 105 of this embodiment includes a driving device 3 for rotatably supporting the disk-shaped magnetic disk 2, A rotation control unit 4 for controlling the rotation of the driving device 3, a support device 5 capable of supporting a thin-film magnetic head 52 whose track pitch is to be measured to face the magnetic recording surface (surface) of the magnetic disk 2, and
A positioning device 6 for moving the thin-film magnetic head 52 via the support device 5 to freely move to a desired position on the magnetic recording surface of the magnetic disk 2, and a recording device for the thin-film magnetic head 52 supported by the support device 5. A recording / reproducing amplifier 7 for amplifying a signal and a reproducing signal; a recording / reproducing control unit 8 connected to the recording / reproducing amplifier 7 for controlling recording / reproducing of the thin-film magnetic head 52; An output detection unit 10 for detecting a signal, a positioning control unit 101 for operating the positioning device 6 to control the positioning of the thin-film magnetic head 52, a position detection unit 102 for detecting the position of the thin-film magnetic head 52, A calculating unit 103 for calculating an N / S curve, which will be described later, in accordance with the signal and noise value detected from the detecting unit 10; And a determination unit 104 the quality of the air head 52 as a major component.

Next, a method for inspecting the thin-film magnetic head 52 using the inspection apparatus 105 having the above-described configuration will be described.
FIGS. 28 to 30 illustrate a fourth embodiment of the present invention. In the fourth embodiment, for example, as shown in FIGS. Read head 61 having effect element as read element
A data signal recorded on a test track on a magnetic recording surface of a disk-shaped magnetic recording medium 2 and a test track thereof using a thin-film magnetic head 52 having a structure in which a write head (inductive head) 62 and a write head 62 are combined and integrated. A noise signal recorded in the periphery, a noise track formed on a test track, an erase track formed by partially overlapping the noise track and a noise track formed on a peripheral track are measured for each position. This is a method for inspecting the magnetic head 52.

First, the thin film magnetic head 5 to be tested
As shown in FIG. 28, the simplified reference data track 140 and the erased simple tracks 141 on both sides thereof are spaced apart from each other on the formatted unused or erased magnetic recording surface of the magnetic recording medium 2 as shown in FIG. Write to.
To write the simple reference data track 140 and the erasure simple tracks 141, 141, the magnetic recording medium 2 is rotationally driven by the driving device 3 and the thin film magnetic recording is performed by the positioning device 6 in the same manner as in the first embodiment. The head 52 is made to face an arbitrary position on the magnetic recording surface of the magnetic recording medium 2, and the write / read head 6 of the thin-film magnetic head 52 is
2, a desired signal is recorded on the magnetic recording surface to form a simple reference data track 140, and then the thin-film magnetic head 52 is moved by the positioning device 6 in the diameter direction of the magnetic recording medium 2 by a predetermined distance. After that, the signals on the magnetic recording surface are erased by the write head 62, whereby the erase reference tracks 141, 141 can be formed.
The simple reference data track 140, the erasure simple tracks 141 and 141, and various tracks to be described later need not be formed on the entire circumference of the recording surface of the magnetic recording medium 2; It may be formed in a sector or a section of a plurality of sectors.

Then, these simple reference data tracks 1
With respect to the magnetic recording surface of the magnetic recording medium 2 on which the simple erase track 141 and a pair of simple erase tracks 141 are formed, the respective tracks 141, 14
The thin film magnetic head 52 to be tested in the width direction of 0, 141 is scanned in the direction of arrow j in FIG. 28 to measure the signal strength at each position in the track width direction. This signal measurement result is shown by a triangular figure indicated by reference numeral 142 in FIG.

Next, as shown in FIG. 29, two simple reference noise tracks 143 are made adjacent to each other at another position on the magnetic recording surface of the magnetic recording medium 2 by using the thin-film magnetic head 52 so as to be separated from each other by a predetermined distance. And write. In order to write these reference simple noise tracks 143, 143, FIG.
The magnetic recording medium 2 is driven to rotate by the driving device 3 shown in FIG. 1, and the thin-film magnetic head 52 is made to face an arbitrary position on the formatted magnetic recording surface of the magnetic recording medium 2 by the positioning device 6. A desired noise signal is recorded on the magnetic recording surface by controlling the power supply to the write head 62 of the thin-film magnetic head 52 to form one simple reference noise track 143, and then the thin-film magnetic head 52 is magnetically recorded by the positioning device 6. After moving by a predetermined distance in the diameter direction of the medium 2, the same noise signal as the previous one is written from the write head 62 to the magnetic recording surface, whereby the second simple reference track 143 can be formed. In addition,
These simple reference noise tracks 143 and various tracks described below do not need to be formed on the entire circumference of the magnetic recording medium 2, but may be formed in a predetermined length, for example, in one sector or a plurality of sectors. good.

The simple reference noise tracks 143, 14
The interval of 3 is set to a width clearly smaller than the track width of the thin film magnetic head 52 to be tested, for example, an interval of about a fraction of the track width. In the test thin-film magnetic head 52, the shape-accurate track width has variations during manufacturing and the like, and it is unknown without accurate measurement. The added magnetic track width and track pitch are unknown, but the simple reference noise track 14 used here is unknown.
The interval between 3 and 143 may be set to an interval which is about a fraction (for example, 1/2) of the track width of the design value of the thin-film magnetic head 52 determined at the time of manufacturing the thin-film magnetic head 52.

Next, these simple reference noise tracks 14
3 and 143, the center of the magnetic recording surface of the magnetic recording medium 2, that is, the center of the interval between the simple reference noise tracks 143 and 143, and the simple reference noise track 14
3 and 143 so that the simple reference erase track 14
Write 5 Subsequently, the simple reference noise track 14
A noise signal is written by using the thin-film magnetic head 52 to be tested at predetermined intervals on both left and right sides of the third and third 143 and the simple adjustment noise tracks 146 and 146 are shown in FIG.
It is formed as shown in FIG. Then, for each track shown in FIG. 29, the thin film magnetic head 52 to be tested in the width direction of the track is scanned in the direction of arrow k in FIG. Is measured.

In the signal recording state of each track, the thin film magnetic head 52 applies a magnetic field to the magnetic recording surface of the magnetic recording medium 2 to perform signal recording. The recording signal gradually weakens from the center to the end, and a portion where the recording signal reaches a region where the intensity is lower than the specified intensity means an end in the track width direction. However, here, a signal weaker than the specified strength is recorded further outside the track end, but the signal of this outer portion is a signal that is not determined to be a recording signal. FIG. 29 shows the distribution of the signal intensity corresponding to each track in consideration of the above state.

In FIG. 29, the area indicated by reference numeral 147 at the center corresponds to the area where the signal has been erased by the simple reference erase track 145. In the signal area of the simple reference noise tracks 143 on both sides of this area, Since a part of the signals of the simple reference noise tracks 143, 143 have been erased by the simple reference erasure track 145, the simplified reference noise tracks 143, 14 after partial erasure have been obtained.
The noise intensity distribution of No. 3 is a triangular noise intensity distribution indicated by reference numerals 148 and 148. In FIG. 29, the noise intensity of the simple reference track 143 before forming the simple reference erase track 145 is indicated by a chain line indicated by reference numeral 149. The noise intensity of the simple adjustment noise track 146 has a triangular distribution indicated by reference numeral 150. Furthermore,
By scanning the thin film magnetic head 52 in the horizontal direction shown in FIG. 29, that is, in the track width direction, the noise intensity at each track position is measured.

Next, the noise (N) at each measurement position obtained in the noise measurement described with reference to FIG. 29 and the signal (N) obtained in the signal measurement described with reference to FIG. The ratio with the signal (S) at each measurement position, that is, the value of the N / S ratio was determined, and FIG.
An N / S curve as shown in FIG. Here, regarding the measurement of the signal strength and the measurement of the noise strength described above, the thin-film magnetic head 52 does not treat the signal as data, but only needs to measure it as the signal strength and the noise strength. Therefore, it is not necessary to incorporate the magnetic head 52 into the hard disk drive, and it is not necessary to measure the signal including the peak jitter and the error rate. Therefore, the measurement can be performed by the thin film magnetic head 52 alone.

From the specification of the thin-film magnetic head 52,
Alternatively, the value of the N / S ratio required from the target performance of the thin-film magnetic head 52 is described with respect to the N / S curve in FIG. 30, and corresponds to the width of the N / S curve in the case of this N / S ratio. If the value of the track pitch falls within the range of the specification required for the thin-film magnetic head 52, the thin-film magnetic head 52 is regarded as an inspection-passed product and is out of the range of the specification. If the track pitch is the same, the thin-film magnetic head 52 is determined to be defective. The calculation of these N / S curves and the determination of non-defective / defective products based on the specifications are performed by the calculation unit 103 in the configuration shown in FIG.
And the determination unit 104.

What is measured in the above processing is both signal strength and noise signal strength, and is a normal signal noise measurement that can be performed by the thin film magnetic head 52 alone. That is, in order to inspect the thin-film magnetic head in the inspection method of the fourth embodiment, signals need not be treated as data, but only signal strength and noise strength need to be measured. There is no need to incorporate the thin-film magnetic head 52 into a hard disk drive device, and it is not necessary to measure the signal including the peak jitter and the error rate.

[0100]

EXAMPLE A thin-film magnetic head designed and manufactured with a track width of 1.8 .mu.m of a write head and a track width of 1.3 .mu.m of a read head and a disk-shaped magnetic recording medium at 5400 rpm was used. A recording / reproduction test was performed while rotating. The interval between a pair of first noise tracks provided on the left and right shown in FIG. 2 is set to 1.0 μm, and the first erase track is gradually approached from a position away from the first noise track. The off-track margin (OTC value) was measured while changing the position every 5 μ inch (0.125 μm) in the area approaching the data track, and the result is shown by the curve indicated by the symbol M in FIG. Subsequently, as in the case shown in FIG. 7, writing to the second data track is started from the position where the second erase track is separated to the left and right, and the second off-track margin (OTC value) at each position is measured. The result is shown by the curve indicated by the symbol N in FIG. Here, the adjacent track position on the horizontal axis in FIG. 31 is the distance from the center of the first data track to the center of the first erase track. FIG. 32 shows the measurement of the signal (S), noise (N) and N / S ratio when the adjacent track position of the M curve of the first off-track margin (OTC value) in FIG. 31 is 120 μ inch (3 μm). An example of the data will be described. The off-track margin (OTC value) in FIG.
The value of the N / S ratio for obtaining the value was 0.2.

As is clear from FIG. 31, in this example, the position of the point where the curve indicated by the symbol M and the curve indicated by the symbol N intersect is the track pitch (85 μ inch: 2.125 μm).
Can be determined.

The method described with reference to FIGS. 2 to 12 is carried out as described above to reduce the track pitch of the thin-film magnetic head in FIG.
1 is obtained from the off-track margin shown in FIG. 1, but when it is determined more accurately than the method described above with reference to FIGS. 2 to 12, the method described above with reference to FIGS. Find the track pitch. Specifically, the track width of the write head is 1.8 μm, and the track width of the read head is 1.3 μm.
The thin disk magnetic head having the structure shown in FIGS.
A signal and a noise were written on the recording surface of the magnetic recording medium while being rotated in the, and a recording and reproducing test was performed.

The interval between the reference noise tracks shown in FIG. 15 is set to 1.0 μm, and the adjustment noise track gradually approaches the reference data track from a position left and right of the reference noise track. Then, the read head was scanned from the center of the reference data track to one of the adjustment noise tracks, and the amount of movement when the N / S ratio was moved to 5: 1 was measured.

FIG. 33 shows an example of the result of the embodiment with a triangle. By referring to the data indicated by the mark “〇” as the result of the example, in the thin-film magnetic head used in this test, the distance between the reference data track and the noise track was 100 to 100.
In the range of 150 μ inch, the moving amount of the read head is 1
It stabilizes at about 4 μ inch (point A), and when the distance between the reference data track and the noise track is 80 μ inch, the movement amount of the read head shows the maximum value (point B), and the distance between the reference data track and the noise track. Becomes smaller, the movement amount of the read head also decreases. Therefore, at point C in FIG. 33, the movement amount of the read head coincides with the value of point A, and thereafter, as the distance between the reference data track and the noise track becomes smaller, The moving amount of the read head decreases. From this figure,
The track pitch including the erase band is the distance between the reference data track and the noise track at point C, that is,
It can be determined that it is about 1.8 μm (72 μ inch).

FIG. 33 also shows actual measured values of the conventional track pitch measuring method shown in FIGS. 39 and 40.
747-in and 747-out shown in FIG. 33 indicate the results of performing the measurement method described above with reference to FIG. That is, assuming that FIG. 39 is the result of 747-in, FIG.
When the relationship shown in FIG.
-out results can be obtained. As described above, the 747 test refers to a plot in which a certain arbitrary (usually 10 ^−4.5 ) error rate is designated, and the relationship between the distance between the reference data track and the noise track, which is the error rate, and the movement amount of the read head. You can see. For example, the first position (203) is point A in FIG. 33, and the movement amount of 205 at that time is T ₁ = T ₃ . If this is the right example, the left example in the case of left-right symmetry is also measured, and the first position in FIG. 39 is on the left. Here, the track width of the write head is 1.8 μm, the track width of the read head is 1.3 μm, and the rotation speed of the magnetic recording medium is 5400 rpm.
m, the error rate was 10 ^−4.5 , and the interval between the pair of noise tracks was 1.0 μm, which was measured by the method described with reference to FIGS. 39 and 40. In the 747 test, 747-in data is the data at the end of the data track on the center side of the magnetic disk of the data track, and 727-o is
The data of ut indicates the data at the end of the data track on the circumferential side of the magnetic disk. Since 747-in and 747-out were exactly the same as the measurement results of the present example, it became clear that the test results of the present example were accurate.

[0106]

As described above, according to the present invention, when magnetic recording and reproduction are performed on a magnetic recording medium using a magnetic head having a write head and a read head, magnetic flux leakage from the write head is prevented. There is a feature that the track pitch in consideration of the fringing width generated in the above can be measured by the magnetic head alone before the magnetic head is mounted on the magnetic recording apparatus. That is, the method of the present invention is particularly effective in measuring the track pitch of a thin-film magnetic head having a fine track whose track width is reduced and the track width is affected by fringing. Even a magnetic head that can only measure the strength of a magnetic head can perform measurement without any trouble.Therefore, there is no need to incorporate it into a magnetic recording device to measure peak jitter and data signal error rates. There is a feature that enables inspection and measurement.

As a specific first measurement method, a pair of first noise tracks, a first data track, and a pair of first erase tracks are used, and all tracks at each position of the first erase track are used. The first off-track characteristic value is obtained from the N / S curve of the second noise track, and the N / S curves of all tracks for each position of the second noise track are used by using the second data track and the pair of second noise tracks. From this, a second off-track characteristic value is obtained, and a method of obtaining a track pitch from a position of a portion where these off-track characteristic values intersect can be carried out.

As a second measurement method, a pair of reference noise tracks, a reference data track, and an adjustment noise track are used to measure the read head movement amount for each position of the adjustment noise track, and the measurement is performed between the reference data track and the noise track. The track pitch can be obtained from the relationship between the interval and the amount of movement of the read head, and the quality of the magnetic head can be determined from the track pitch.

As a third measurement method, a signal is obtained from the positional relationship between the first reference simple data track and the pair of first simple erasure tracks, and a signal is obtained from the pair of reference simple tracks and the pair of adjustment tracks with respect to the reference simple erasure track. Noise is obtained from the positional relationship, an N / S curve is obtained from the ratio of the noise to the signal, and a signal is obtained from the second reference simple data track and the second simple erase track. Noise is obtained from the positional relationship between the pair of second adjustment simple tracks with respect to the second reference simple erasure track, and an N / S curve is obtained from the ratio of the noise and the signal. The magnetic head used for measurement is judged as a non-defective product if it exceeds the width of the magnetic head. Can.

As a fourth measurement method, noise is determined from the positional relationship between the simple reference data track and the erased simple track, and noise is determined from the position of the pair of simple reference noise tracks and the pair of simple adjustment noise tracks with respect to the simple reference erase track. N / S calculated from the ratio of noise to signal
If the width of the curve exceeds the specified use width, the magnetic head used for measurement can be determined as a non-defective product if the magnetic head used for measurement is less than the use width.

Next, the apparatus of the present invention reads and writes signals on the magnetic recording medium by using the magnetic recording medium rotation driving device, the magnetic head positioning device, and the magnetic head when the above-described methods are performed. A recording / reproducing control unit for measuring the track pitch can be obtained by obtaining the N / S curve of each track by the method described above. Therefore, it is possible to provide an apparatus capable of determining whether the magnetic head is good or bad by determining whether or not the track pitch of the magnetic head is within a specified range based on the track pitch value thus measured. be able to.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a magnetic head track pitch measuring device and a magnetic head inspection device according to the present invention.

FIG. 2 illustrates a first noise track and a first noise track recorded on a magnetic recording medium when the method according to the first embodiment of the present invention is performed.
FIG. 4 is a plan view showing a positional relationship between a data track and a first erase track.

3 is a schematic diagram showing a cross-sectional view of a mutual positional relationship among a first noise track, a first data track, and a first erase track shown in FIG. 2;

FIG. 4 is a diagram showing a signal or noise intensity distribution of a first noise track, a first data track, and a first erase track shown in FIG. 2;

5 is an N / S curve for each measurement position obtained from signals and noises of a first noise track, a first data track, and a first erase track shown in FIG. 2, and the N of the thin-film magnetic head;
The figure which shows the relationship of the performance requirement value of / S ratio.

6 is a diagram in which a first off-track characteristic value obtained from the N / S curve and the performance requirement value shown in FIG. 5 is plotted for each first erase track position shown in FIG.

FIG. 7 shows a second data track and a second data track recorded on a magnetic recording medium when the method according to the first embodiment of the present invention is performed.
FIG. 6 is a plan view showing the positional relationship between erase tracks.

FIG. 8 shows a second noise track and a second noise track recorded on a magnetic recording medium when the method according to the first embodiment of the present invention is performed.
FIG. 2 is a plan view showing the positional relationship between data tracks.

9 is a schematic view showing a second noise track and a second data track shown in FIG. 8 in a sectional view.

FIG. 10 is a diagram showing a signal or noise intensity distribution of a second data track and a second noise track shown in FIG. 8;

FIG. 11 is a diagram showing a relationship between an N / S curve obtained from signals and noises of a second data track and a second noise track shown in FIG. 8 and a performance request value of the thin-film magnetic head.

12 is a diagram plotting a comparison between a second off-track characteristic value for each position obtained from the N / S curve shown in FIG. 11 and a first off-track characteristic value shown in FIG. 6;

FIG. 13 is a configuration diagram showing a second embodiment of a magnetic head track pitch measuring device and a magnetic head inspection device according to the present invention.

FIG. 14 is a plan view showing the relationship between a track written on a magnetic recording surface of a magnetic recording medium by a magnetic head to be measured in the present invention and an erase band.

FIG. 15 is a plan view showing a state where a reference noise track, a reference data track, and an adjustment noise track are formed on a magnetic recording surface.

FIG. 16 is a plan view showing a state where an adjustment noise track is brought close to a reference data track.

FIG. 17 is a plan view showing a position where an erase band of an adjustment noise track is superimposed on an erase band on both sides of a reference data track.

FIG. 18 is a plan view showing a state where an adjustment noise track is superimposed on both sides of a reference data track.

FIG. 19 is a diagram in which the measurement results obtained in FIGS. 14 to 18 are plotted.

FIG. 20 is a configuration diagram showing a third embodiment of the inspection apparatus of the present invention.

FIG. 21 is a view for explaining a third embodiment of the inspection method according to the present invention, in which the first reference simple track is provided on both sides with the first reference simple track;
FIG. 3 is a plan view showing a state in which a simple erase track is formed.

FIG. 22 is a view for explaining a third embodiment of the inspection method of the present invention, in which a pair of reference simple noise tracks, a reference simple erase track formed therebetween, and a reference simple track formed on both sides of the reference simple track; The top view which shows the positional relationship of the adjusted simple truck.

FIG. 23 is a view for explaining a third embodiment of the inspection method of the present invention, and is a diagram showing an N / S curve indicating a ratio of a signal to noise obtained from each track shown in FIGS. 21 and 22.

FIG. 24 is a plan view for explaining a third embodiment of the inspection method of the present invention, showing a state where second simple erase tracks are formed on both sides of a second reference simple data track.

FIG. 25 is a view for explaining the third embodiment of the inspection method of the present invention, in which a second reference simple track is formed between a pair of second reference simple tracks, and the second reference simple track is formed. FIG. 9 is a plan view showing a state where second adjustment simple noise tracks are formed on both sides.

26 is a view for explaining the third embodiment of the inspection method of the present invention, and is a view showing a result of calculating a noise / signal ratio for each position from the signal shown in FIG. 24 and the noise shown in FIG. 25.

FIG. 27 is a configuration diagram showing a fourth embodiment of the inspection apparatus of the present invention.

FIG. 28 is a plan view for explaining a fourth embodiment of the inspection method of the present invention, showing a state in which erase simple tracks are formed on both sides of a simple reference data track.

FIG. 29 is a view for explaining a fourth embodiment of the inspection method of the present invention, in which a pair of simple reference noise tracks, a simple reference erase track formed so as to overlap with the pair of simple reference noise tracks, and a simple reference erase track adjacent to the simple reference erase track. FIG. 4 is a plan view showing a positional relationship of a simple noise track formed by the above.

FIG. 30 is a diagram plotting the ratio of noise to signal obtained from each track shown in FIGS. 28 and 29.

FIG. 31 is a diagram in which the first off-track characteristic and the second off-track characteristic obtained in the example are plotted in one graph.

FIG. 32 is a view showing a result of obtaining a noise / signal ratio from a signal and a noise value obtained in the example.

FIG. 33 is a view showing a curve obtained by the method described with reference to FIGS. 14 to 18 in the example.

FIG. 34 is a perspective view showing an example in which a general thin-film magnetic head is mounted on a slider.

FIG. 35 is a sectional view of the thin-film magnetic head slider shown in FIG. 34;

FIG. 36 is an enlarged view showing a write head and a read head of the thin-film magnetic head slider shown in FIG. 34;

FIG. 37 is a diagram showing variations in sensitivity of a magnetoresistive multilayer film used for a general thin-film magnetic head.

FIG. 38 is a diagram showing a normalized output for each position in a data track.

FIG. 39 is a diagram showing an example of a conventional method for measuring a track pitch of a thin-film magnetic head.

FIG. 40 is a diagram showing off-track characteristic values for each adjustment track position obtained by the method of measuring the track pitch of the thin-film magnetic head described in FIG. 39;

[Explanation of symbols]

1, 45, 95, 105 ... inspection device, 2 ... magnetic recording medium, 3 ... drive device, 6 ... positioning device, 8 ... recording and reproduction control unit, 11, 41, 91, 101: Positioning control unit, 13, 43, 93, 103: Operation unit, 14, 4
4, 94, 104: determination section, 21, 22: first noise track, 23: first data track, 25, 2
6 first erase track, 30 second data track, 31, 32 second erase track, 33, 34,
2nd noise track, 52 ... thin-film magnetic head, 8
0, 81: Reference noise track, 82, 83: Adjustment noise track, 85: Reference data track, 110:
1st reference simple data track, 111 ... first simple erase track, 113 ... reference simple noise track, 1
15: reference simple erasure track, 116: adjustment simple noise track, 123: second reference simple data track, 124: second simple erasure track, 130: second
Reference simple noise track 131, second reference simple erase track 133, second adjustment simple noise track 140, simple reference data track 141 simple erase track, 143・ Simple reference noise track, 1
45: Simple reference erase track, 146: Simple adjustment noise track.

Claims (16)

[Claims] A magnetic head having a write head and a read head is used to form a pair of adjacent first noise tracks on a magnetic recording medium that are spaced apart from each other, and are formed on the first noise tracks. A first data track is written so that both ends in the width direction overlap with each other, and a pair of first erase tracks is further formed on both sides in the width direction of the first data track by being separated from the first data track by a predetermined distance. In addition, the signal strength and the noise strength at each predetermined position are measured using the magnetic head along the width direction of all these tracks, and the ratio between them is calculated (noise / signal).
An N / S curve indicating a ratio is obtained, and a first off-track characteristic value is obtained from a contact point of the N / S curve with respect to a (noise / signal) ratio required for the magnetic head. The position of the pair of first erase tracks to be formed is gradually approached or separated from the first data track to obtain a first off-track characteristic value for each position of the first erase track. A second data track is formed on a magnetic recording medium using the magnetic head, and after forming a pair of second erase tracks on both sides of the second data track, a signal of the second data track is measured. Then, noise is written on each of the pair of second erase tracks to form a second noise track, and the magnetic tracks are formed along the width direction of all the tracks. The signal strength and the noise strength at each predetermined position are measured using a head, and the ratio between them is calculated to obtain an N / S curve indicating a (noise / signal) ratio. / Signal) ratio to the N /
A second off-track characteristic value is obtained from a contact point of the S-curve, and the formation position of the pair of second erase tracks formed with respect to the second data track is gradually approached to or close to the second data track. A second off-track characteristic value for each position of the second erase track is obtained by separating the first off-track characteristic value from the first erase track position. A method of measuring a track pitch of a magnetic head, comprising: comparing the off-track characteristic value of each second erase track position with each other to determine a track pitch from an erase track position at a point where the two off-track characteristic values match. . 2. A method according to claim 1, wherein the first data track and the pair of first erase tracks are gradually made closer to each other to obtain a first off-track characteristic value for each first erase track position. Wherein the position of the erase track is gradually moved from a position outside the first noise track to a position overlapping with the first data track, and a first off-track characteristic value is obtained for each movement position. Item 2. A method for measuring a track pitch of a magnetic head according to Item 1. 3. The method according to claim 2, wherein the second off-track characteristic value for each second erase track position is obtained by gradually reducing the distance between the second data track and the pair of second erase tracks. From the position separated from the data track of
3. The track pitch measuring method according to claim 1, wherein the second erasing track is gradually moved to a position overlapping the data track, and a second off-track characteristic value is obtained for each moving position. . 4. A method for measuring a signal strength and a noise strength at each predetermined position using the magnetic head along a width direction of all the tracks, and calculating a ratio between the signal strength and the noise strength. When calculating the N / S curve indicating the signal strength, the signal strength and the noise strength are separately measured, and based on these values, the N / S curve is calculated.
4. An S / S curve is obtained.
The method for measuring a track pitch according to any one of the above. 5. A method for inspecting a magnetic head, comprising determining whether the magnetic head is good or bad based on the track pitch measured by the method according to claim 1. 6. A drive device for supporting and rotating a disk-shaped magnetic recording medium, a positioning device for positioning a magnetic head for inspection with respect to an arbitrary position on a recording surface of the magnetic recording medium, and The write head and the read head provided on the inspection magnetic head are energized to control data tracks, erase tracks, and noise tracks at arbitrary positions on the recording surface of the magnetic recording medium, and the signals of the data tracks are recorded. 5. A recording / reproducing control unit for making it possible to read noise of a noise track, wherein the driving device, the positioning device and the recording / reproducing control unit are used. And a calculating unit for calculating the track pitch of the inspection magnetic head by performing the track pitch measuring method. . 7. The configuration according to claim 6, further comprising a determination unit for determining whether the magnetic head for inspection is good or defective based on the track pitch calculated by the calculation unit. Inspection device for magnetic head. 8. A magnetic head having a write head and a read head is used to form a pair of adjacent reference noise tracks spaced apart from each other on a magnetic recording medium, and both ends in the width direction are formed on these reference noise tracks. The reference data track is written so as to overlap the portion, and a pair of adjustment noise tracks are formed on both sides in the width direction of the reference data track so as to be separated from the reference data track by a predetermined distance,
The magnetic head is scanned from the inside of the reference data track toward the outside of the reference data track along the track width direction to measure the signal strength and noise strength of the magnetic head read out signal. The movement amount of the magnetic head until a predetermined (noise / signal) ratio is obtained is obtained, and the formation position of the adjustment noise track formed with respect to the reference data track is gradually approached or separated from the reference data track. Calculating the amount of movement of the magnetic head at each position where the adjustment noise track is formed, and calculating the track pitch of the magnetic head from the state of change in the amount of movement of the magnetic head at each position of the adjustment noise track. Track pitch measurement method. 9. The position where the adjustment noise track is formed is set from a position apart from the reference data track in a track width direction of the reference data track to a position overlapping with the reference data track. The method of measuring a track pitch according to claim 8. 10. A good or bad magnetic head based on a track pitch measured by the method according to claim 8.
A method for inspecting a magnetic head, comprising determining a defect. 11. A driving device for supporting and rotating a disk-shaped magnetic recording medium, a positioning device for positioning a magnetic head for inspection with respect to an arbitrary position on a recording surface of the magnetic recording medium, and A write head and a read head provided on the inspection magnetic head are energized so that data tracks, erase tracks, and noise tracks can be recorded on the magnetic recording medium, and signals of the data tracks and noise of the noise tracks are read. 10. A method for measuring a track pitch according to claim 8, further comprising: a recording / reproducing control unit for enabling the recording / reproducing control unit. A track pitch measuring device, comprising: a calculation unit for calculating a track pitch of a magnetic head for inspection. 12. The apparatus according to claim 11, further comprising a determination unit for determining whether the magnetic head for inspection is good or defective based on the track pitch calculated by the calculation unit. Inspection device for magnetic head. 13. A first reference simple data track is written on a magnetic recording medium using a magnetic head having a write head and a read head. A pair of first simple erasure tracks are formed at a predetermined interval from the first reference simple data track, and the magnetic head is scanned along the track width direction of the first reference simple data track to scan each scanning position. And a pair of first reference simple noise tracks spaced apart from each other and formed on the magnetic recording medium using the magnetic head. A first reference simple erase track is written so that both ends in the width direction overlap with each other, and the first reference simple erase track is further written on both sides in the width direction of the first reference simple erase track. A pair of first adjusted simple noise tracks is formed at a predetermined distance from the noise track, and the magnetic head is scanned in the track width direction of the first adjusted simple noise track to reduce the noise intensity at each scanning position. While measuring, the ratio of the noise intensity to the signal intensity for each of the separately measured scanning positions is determined for each of the measurement positions, while using the thin-film magnetic head, a second reference simple data track is formed on a magnetic recording medium. Writing, and further forming a second simple erase track on both sides of the second standard simple data track so as to partially overlap the second simple standard data track, and in the track width direction of the second standard simple erase track. Scans the magnetic head along to measure the signal strength at each scanning position, and uses the magnetic head to separate a pair of second A reference simple noise track is formed, a second reference simple erase track is written on the second reference simple noise track so that both ends in the width direction overlap, and both sides in the width direction of the second reference simple erase track are further written. Forming a pair of second adjusted simple noise tracks partially overlapping with the second reference simple erase track;
The magnetic head is scanned in the track width direction of the second adjusted simple noise track to measure the noise intensity at each scanning position, and the noise intensity and signal intensity at each of the separately measured scanning positions are measured. The ratio is obtained for each measurement position, and the ratio between the noise intensity and the signal intensity for each scanning position obtained previously and the ratio between the noise intensity and the signal intensity for each scanning position obtained later are both obtained. A method for inspecting a magnetic head, comprising: determining a magnetic head as a non-defective product if the ratio is higher than a ratio of a noise intensity to a signal intensity required for the magnetic head; 14. A driving device for supporting and rotating a disk-shaped magnetic recording medium, a positioning device for positioning a magnetic head for inspection with respect to an arbitrary position on a recording surface of the magnetic recording medium, and A write head and a read head provided on the inspection magnetic head are energized so that data tracks, erase tracks, and noise tracks can be recorded on the magnetic recording medium, and signals of the data tracks and noise of the noise tracks are read. 14. A recording / reproducing control unit for enabling the method, wherein the driving device, the positioning device, and the recording / reproducing control unit are used to perform the method according to claim 13, and the noise intensity and the signal obtained are obtained. An inspection apparatus for a magnetic head, comprising: a determination unit for determining whether the inspection magnetic head is good or defective based on the ratio of the strengths of the magnetic heads. 15. A simple reference data track is written on a magnetic recording medium by using a magnetic head having a write head and a read head. A pair of erasing simple tracks is formed at intervals, and the magnetic head is scanned along the track width direction of the simple reference data track to measure the signal strength at each scanning position. Forming a pair of simple reference noise tracks adjacent to each other on the magnetic recording medium, and writing a simple reference erase track on these simple reference noise tracks so as to overlap both ends in the width direction. The simplified reference noise track is separated from the simplified reference noise track by a predetermined distance on both sides in the width direction of the erased track. By partially overlapping to form a simple noise track,
The magnetic head is scanned in the track width direction of each track to measure the noise intensity at each scanning position, and the ratio of the noise intensity at each scanning position and the signal intensity measured separately is measured at each measurement position. If the ratio between the noise intensity and the signal intensity is higher than the ratio between the noise intensity and the signal intensity required for the magnetic head, the magnetic head is determined to be good, and if the ratio is low, it is determined to be defective. A method for inspecting a magnetic head, comprising: 16. A driving device for supporting and rotating a disk-shaped magnetic recording medium, a positioning device for positioning a magnetic head for inspection with respect to an arbitrary position on a recording surface of the magnetic recording medium, and A write head and a read head provided on the inspection magnetic head are energized so that data tracks, erase tracks, and noise tracks can be recorded on the magnetic recording medium, and signals of the data tracks and noise of the noise tracks are read. 16. A recording / reproducing control unit for enabling the method, wherein the driving device, the positioning device, and the recording / reproducing control unit are used to carry out the method according to claim 15, and the obtained noise intensity and signal are obtained. An inspection apparatus for a magnetic head, comprising: a determination unit for determining whether the inspection magnetic head is good or defective based on the ratio of the strengths of the magnetic heads.