JP3828662B2 - Signal defect inspection method for magnetic disk - Google Patents

Description

とで再生時の高ＳＮ比（信号対ノイズ比）とハードディスクメディアドライブ装置におけるヘッドとハードディスクメディアの機械的位置合わせ誤差による再生エラーが生じにくいという利点を得ている。」とある他、特開平６−１６２４５１号公報、特開平７−４４８２０号公報の図面に開示されているように、記録トラック幅を再生トラック幅より広くするように設定することが主流であった。
【０００８】
しかし、近年の目覚ましい記録密度の向上に伴い、記録トラック幅も２μｍ以下にまで減少の一途であり、記録トラック幅も２μｍ以下のものが市場に出されている。このため記録トラック幅を有効に利用する必要が生じ、最近では特開平８−１８５６１３号公報の第４頁左欄第２６行目から第３０行目に「誘導型磁気ヘッド１４による書き込みトラック幅Ｔｗは上コア４０のポール幅で規定され、ＭＲ膜４６の活性部４６ｃの幅（リード３０、３１間の距離）はトラック幅ＴＷに略々等しく設定される。」とある他、特開平７−６５３２５、特開平８−６５３２５、特開平９−２９３２１３の記録素子部とＭＲ素子部の位置決め精度を改善するための特許の図面に見られるように、記録トラック幅とＭＲ素子による再生トラック幅をほぼ等しくした複合型薄膜磁気ヘッドが主流となってきている。
【０００９】
【発明が解決しようとする課題】
上述したような記録トラック幅とＭＲ素子による再生トラック幅をほぼ等しくした複合型薄膜磁気ヘッドを用いる場合、上記公開特許出願等によっても生産上避けがたい記録素子部とＭＲ素子部の位置ずれが残存しているため、磁気ディスク装置における位置補正技術が不可欠である。この補正は通常、記録信号の一部に書き込まれたサーボ信号を用いて行われる、いわゆるデータ面サーボ技術を用いて行われる。しかし、通常の磁気ディスクの欠陥検査装置においてはそういうデータ面サーボによるオントラック機構を持たないため、記録トラック位置と再生トラック位置のずれに起因して、再生時に記録トラックからの出力が十分に得られず、欠陥検査の測定が出来なくなる現象が発生する。
【００１０】
更に記録トラック位置と再生トラック位置のずれが生じているため、記録トラックのエッジ部分を再生することにより、磁気ディスクに存在する欠陥以外の場所を欠陥として検出してしまうという問題が生じてしまう。
【００１１】
本発明の目的は、最近の狭トラック化された再生用ヘッドに対する微小な欠陥を検査可能な検査方法を提供することにある。
【００１３】
【課題を解決するための手段】
上記目的を達成するために、記録用の薄膜磁気ヘッドと再生用の薄膜磁気ヘッドとが一体化された複合型の検査用磁気ヘッドを用いて磁気ディスクの信号欠陥検査を行う、磁気ディスクの信号欠陥検査方法において、検査用磁気ヘッドは、記録用の薄膜磁気ヘッドの素子幅が再生用の薄膜磁気ヘッドの素子幅の２．１２倍以上の幅で、再生用の薄膜磁気ヘッドの素子幅に対する記録用の薄膜磁気ヘッドの素子幅の比が磁気ディスクを使用する予定の磁気ディスク装置の磁気ヘッドの該当する素子幅の比より大きいものを使用し、記録用の薄膜磁気ヘッドで磁気ディスクの検査する１トラックの一周に検査用の記録パターンを記録し、それを再生用の薄膜磁気ヘッドで再生し、次に記録用の薄膜磁気ヘッドで次の検査するトラックの一周に検査用の記録パターンを記録し、それを再生用の薄膜磁気ヘッドで再生するという動作を順次繰り返し、再生用の薄膜磁気ヘッドで再生した各トラックの信号を検査する。その理由を下記に説明する。
【００１４】
まず、磁気ディスクの欠陥検査においては、一つのトラックに一周分の検査用の記録パターンを記録して、それを再生して見ることにより、信号の欠落等の異常を検出して信号欠陥を知る。次に、隣のトラックの検査の際には、前のトラックの検査のパターンが書かれてしまっているが、そのトラックに上書きして前の検査パターンを消してしまってから検査すれば良いのであって、前の検査パターンが影響することは何等発生しない。ここで、このトラックの検査のために書き込んだ記録パターンにより前のトラックの記録パターンは消されてしまうが、それは残っている必要の無いものであるから、これも何の問題もない。即ち、上記のように、実際の磁気ディスク装置では使用しない幅の広い記録トラック幅で検査用パターンを記録しても、磁気ディスクの欠陥検査を目的とする場合、何の問題もないのである。
【００１５】
一方、再生出力の面から見ると次のようになる。
【００１６】
図５は本発明の広い記録トラック幅の記録素子部で記録した後、目的の狭い再生トラック幅のＭＲ素子を持つ磁気ヘッドで再生した出力と、従来の記録トラック幅と再生トラック幅がほぼ等しい磁気ヘッドで再生した出力を、再生時に半径方向へ移動（オフセット）して測定した結果を示す。
【００１７】
従来の磁気ヘッドを用いた場合、再生出力が半径位置に対して急激に増加、減少するのに対し、本発明の磁気ヘッドを用いた場合、変化が比較的緩やかな領域を持つことが分かる。即ち、従来の磁気ヘッドを用いた場合、記録素子部と再生用ＭＲ素子部の位置が少しでもずれると、急激に出力が減少するため、ノイズと欠陥を判別し難くなり、欠陥検査に支障を来す。
【００１８】
一方、本発明の場合、多少の記録素子と再生用ＭＲ素子部の位置ずれは許容出来ることがわかる。さらに本発明者は、本発明の磁気ヘッドにおいてこのような比較的緩やかな領域を充分な広さで作るには、記録素子部の幅が、再生用ＭＲ素子部の幅の２倍以上あればよいことを見出した。
【００１９】
【発明の実施の形態】
以下、本発明の一形態による磁気ヘッドを説明する。本発明の実施形態を示した磁気ヘッド素子部拡大図を図１に示す。また本実施形態の磁気ヘッドの記録／再生用素子の位置関係モデル図を図２に示す。図１及び図２で、１１はＣｏＮｉＦｅなどからなる上部磁性膜、１２はＣｕ、Ｃｒなどからなるコイル、１３はＮｉＦｅＮなどからなる上部シールド膜兼下部磁性膜、１４はＮｂ、Ａｕ、Ｎｂなどからなる電極、１５はＮｉＦｅなどからなるＭＲセンサ膜、１６はＮｉＯなどからなる磁区制御膜、１７はＮｉＦｅＮなどからなる下部シールド膜である。いずれの膜もスパッタリングなどにより形成される。また各膜構成部分をまとめて、０１が記録用素子、０２が再生用素子の磁束感知部である。図２で、ａは記録用ヘッドの素子幅、ｂは再生用ヘッドの素子幅である。
【００２０】
図２に示す如く、記録用素子０１の幅ａは１．８０μｍ、再生用素子０２の幅ｂは０．８５であり、記録用素子０１の幅ａは再生用素子幅ｂの２．１２倍と１．５倍以上の幅で構成されている。
【００２１】
また本実施形態の磁気ヘッドの比較として、従来技術を用いている磁気ヘッドの記録／再生用素子の位置関係モデル図を図３に示す。図３に示す如く、記録用素子０１の幅ａは１．３５μｍ、再生用素子０２の幅ｂは０．９５であり、記録用素子０１の幅ａは再生用素子幅ｂの１．４２倍と１．５倍以下の幅で構成されている。
【００２２】
本実施形態による磁気ヘッド及び従来技術を用いている磁気ヘッドの組立図を図４に示す。図４で４１は前記磁気ヘッド素子を備えた磁気ヘッドをスライダに加工したもの、４２はスライダ４１を搭載し、弾性的に支持するサスペンションである。
【００２３】
本実施形態では、図２の本発明磁気ヘッドを磁気ディスクの欠陥検査に用いた。また比較として図３の従来技術磁気ヘッドを、同一磁気ディスクの欠陥検査として用いた。欠陥検査の測定としては、まず高周波信号を磁気ディスクの所定のトラックに記録素子０１により書込み、その後再生素子０２により、そのトラック１周の平均読み出し電圧を測定する。所定のトラックにおいて、記録・再生の阻害要因となる欠陥個所が存在した場合には、モジュレーションエラーやミッシングエラー、エキストラエラー及びスパイクエラーなどとして観測される。
【００２４】
エラーと測定された場合には、再度、高周波信号を磁気ディスクの所定のトラックに記録素子０１により書込み、その後再生素子０２により、そのトラック１周の平均読み出し電圧を測定する。このように再度のエラー測定（リトライ動作）によってもエラーと判定された場合に、エラーとしてカウントされる。この測定を磁気ディスクの指定の範囲にて行うことにより、磁気ディスクの総欠陥個数が判定される。
【００２５】
本発明磁気ヘッドと、従来技術磁気ヘッドのオフセットプロファイルを図５に示す。ここで、オフセットプロファイルとは、再生時に半径方向へ移動（オフセット）して出力を測定した結果である。図５で、５１は本発明磁気ヘッドのオフセットプロファイル、５２は従来技術磁気ヘッドのオフセットプロファイルである。図５に示す如く、本発明磁気ヘッドのオフセットプロファイルは、幅の広い緩やかな変化を示しており、再生トラックの位置でも充分な出力を持つことが分かる。
【００２６】
それに対し、従来技術磁気ヘッドのオフセットプロファイルは、再生出力のピーク値を示す位置が、記録トラック位置とは異なることから、記録トラック位置と再生トラック位置がずれており、しかも変化が急峻であることが分かる。従って、エラー測定は記録トラック位置で行われるため、従来技術磁気ヘッドの記録トラック位置での出力は、０．１９５ｍＶｐｐと減少する。本実施形態にて使用した欠陥検査装置では、エラー測定時の出力が０．２００ｍＶｐｐ以下の場合、Ｓ／Ｎ不足となり、エラー測定におけるリトライ動作が増加し、測定時間が増加する。
【００２７】
また、検出されるエラーの欠陥数及び欠陥サイズ、欠陥位置などの再現性が悪化する。本実施形態に使用した従来技術磁気ヘッドを用いたエラー測定においては、本発明磁気ヘッドを用いたエラー測定よりも、エラー測定時間が延長した。また、繰り返しエラー測定を行った場合にも、本発明磁気ヘッドを用いたエラー測定においては、検出されるエラーの欠陥数及び欠陥サイズ、欠陥位置などが再現性したが、従来技術磁気ヘッドを用いたエラー測定においては、エラー測定の結果に再現性が認められず、エラー測定における、磁気ディスクの欠陥判定は、不可能となってしまった。
【００２８】
本発明磁気ヘッドで磁気ディスクの欠陥検出を行った場合のエラーマップを図６に示す。また従来技術磁気ヘッドで同一の磁気ディスクの欠陥検出を行った場合のエラーマップを図７に示す。図６と図７を比較すると、従来技術磁気ヘッドで磁気ディスクの欠陥検出を行った場合の方が、欠陥として検出される量が多くなることが分かった。また繰り返し欠陥検出を行った場合、本発明磁気ヘッドで欠陥検出を行った場合には、測定の再現性があるのに対し、従来技術磁気ヘッドで欠陥検出を行った場合には測定の再現性がないことが分かった。
【００２９】
更に本発明磁気ヘッドで欠陥検出される個所に関して欠陥分析を行ったところ、膜剥がれなどの欠陥が検出されたのに対し、従来技術磁気ヘッドで欠陥検出される個所に関して欠陥分析を行ったところ、何も検出されなかった。この結果より、従来技術磁気ヘッドでは、記録トラック位置と再生トラック位置のずれに起因して、再生時に記録トラックからの出力が十分に得られず、Ｓ／Ｎ不足となり、エラー測定におけるリトライ動作の増加により測定時間が増加し、欠陥検査の測定が再現出来なくなる現象が発生していることが分かった。
【００３０】
更に記録トラック位置と再生トラック位置のずれが生じているため、記録トラックのエッジ部分を再生することにより、磁気ディスクに存在する欠陥以外の場所を欠陥として検出してしまうという問題が生じていることが分かった。
【００３１】
【発明の効果】
以上説明したように、本発明の磁気ヘッドは、記録用の薄膜磁気ヘッドと、再生用の薄膜磁気ヘッドとが一体化された複合型薄膜磁気ヘッドを、磁気ディスクの欠陥検査装置に用いる場合、一般的には磁気ディスク装置と同様の薄膜磁気ヘッドが用いられるため、磁気ディスク装置の高記録密度化に伴って、記録トラック幅、再生トラック幅共に２μｍ以下に狭トラック化された薄膜磁気ヘッドを使用せざるを得ないため、記録トラック位置と再生トラック位置のずれに起因して、再生時に記録トラックからの出力が十分に得られず、欠陥検査の測定が出来なくなる現象が発生する。
【００３２】
そこで、記録用素子幅を狭トラック化せずに、記録用素子幅を、再生用素子幅の１．５倍以上の幅で構成することにより、トラック幅２μｍ以下においても磁気ディスクの欠陥検査が可能となる。
【図面の簡単な説明】
【図１】本発明の実施形態を示した磁気ヘッド素子部の拡大図。
【図２】本実施形態の磁気ヘッドの記録／再生用素子の位置関係を示すモデル断面図。
【図３】従来技術を用いている磁気ヘッドの記録／再生用素子の位置関係を示すモデル断面図。
【図４】本実施形態による磁気ヘッド及び従来技術を用いている磁気ヘッドの組立斜視図。
【図５】本発明磁気ヘッドと従来技術磁気ヘッドのオフセットプロファイルを示す特性図。
【図６】本発明磁気ヘッドで磁気ディスクの欠陥検出を行った場合のエラーマップ図。
【図７】従来技術磁気ヘッドで磁気ディスクの欠陥検出を行った場合のエラーマップ図。
【符号の説明】
０１…記録用素子、０２…再生用素子、１１…上部磁性膜、１２…コイル、
１３…上部シールド膜兼下部磁性膜、 １４…電極、１５…ＭＲセンサ膜、
１６…磁区制御膜、１７…下部シールド膜、 ４１…スライダ、
４２…サスペンション。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic head for detecting the presence or absence of a defective portion that is an obstructive factor for recording / reproducing on a magnetic disk, and an inspection method using the magnetic head.
[0002]
[Prior art]
In recent years, there is an increasing demand for higher density storage devices such as magnetic disk devices in computer peripheral devices. The magnetic disk device is composed of a magnetic head and main components of the magnetic disk. The magnetic disk rotates at a high speed, and the magnetic head floats or runs on the surface of the magnetic disk at a gap of a submicron order. For magnetic disks, a base film such as Cr is deposited on a nonmagnetic substrate such as an Al alloy substrate plated with Ni-P or a glass substrate coated with a nonmagnetic intermediate film by vapor deposition or sputtering. A metal thin film comprising a Co-based alloy magnetic film having uniaxial magnetic anisotropy, such as CoCrPt, CoNiCr, CoCrTa, etc., and further comprising a protective film and a lubricating film excellent in sliding resistance and corrosion resistance. Type magnetic recording media are used.
[0003]
It is desirable that there are no defective parts that obstruct recording / reproduction as a required characteristic of magnetic disks, but in fact, defects may occur due to various factors in the manufacturing process of magnetic disks. The manufactured magnetic disk needs to be inspected for exceeding the allowable number of defects and the defect size.
[0004]
As a measurement for defect inspection of a magnetic disk, first, a high-frequency signal is written on a predetermined track of the magnetic disk by a recording element, and then an average read voltage for one round of the track is measured by a reproducing element. If there is a defect location that hinders recording / reproduction in a predetermined track, it is observed as a modulation error, missing error, extra error, spike error, or the like.
[0005]
A magnetic head used for defect inspection of a magnetic disk is usually the same thin film magnetic head as a magnetic disk device using the same, and in recent years, a magnetoresistive head utilizing a magnetoresistive effect corresponding to a high recording density. (Magneto reactive head, hereinafter referred to as MR head) is used. For example, as described in Japanese Patent Application Laid-Open No. 6-4832, this MR head has a magnetic head portion for recording (hereinafter referred to as a recording element portion) and a magnetic sensitive portion (hereinafter referred to as MR) by a reproducing MR element. Is a composite type thin film magnetic head that is stacked and integrated vertically, and the positions of the recording track recorded by the recording element unit and the reproduction track where the recording is reproduced by the MR element unit are determined. Various ideas for matching are provided.
[0006]
Here, since recording is performed concentrically in the magnetic disk device, one concentric recording area is called a track. In such a composite thin film magnetic head, the positions of the recording unit and the reading unit are different. This is called because it is necessary to distinguish the recording track that has been written and the reproduction track in the sense that the MR element reads the recording.
[0007]
As such a track positioning technique, conventionally, the third page, left column, lines 11 to 17 in Japanese Patent Laid-Open No. Hei 6-4832 are referred to as “2 gap type MR / In

Thus, there is an advantage that a reproduction error due to a high SN ratio (signal-to-noise ratio) at the time of reproduction and a mechanical alignment error between the head and the hard disk medium in the hard disk media drive apparatus hardly occurs. In addition to the above, as disclosed in the drawings of JP-A-6-162451 and JP-A-7-44820, it has been mainstream to set the recording track width to be wider than the reproduction track width. .
[0008]
However, with the remarkable improvement in recording density in recent years, the recording track width has been reduced to 2 μm or less, and a recording track width of 2 μm or less has been put on the market. For this reason, it is necessary to use the recording track width effectively. Recently, the "write track width Tw by the induction type magnetic head 14" is shown in the left column, page 26, line 30 to line 30, of JP-A-8-185613. Is defined by the pole width of the upper core 40, and the width of the active portion 46c of the MR film 46 (the distance between the leads 30 and 31) is set substantially equal to the track width TW. " 65325, Japanese Patent Laid-Open No. 8-65325, and Japanese Patent Laid-Open No. 9-293213, the recording track width and the reproduction track width by the MR element are almost equal to each other. Equalized composite thin film magnetic heads are becoming mainstream.
[0009]
[Problems to be solved by the invention]
In the case of using a composite thin film magnetic head in which the recording track width and the reproducing track width by the MR element are substantially equal as described above, the positional deviation between the recording element portion and the MR element portion, which is unavoidable in production even by the above-mentioned published patent application, etc. Since it remains, position correction technology in the magnetic disk device is indispensable. This correction is usually performed using a so-called data surface servo technique, which is performed using a servo signal written in a part of the recording signal. However, since a normal magnetic disk defect inspection apparatus does not have such an on-track mechanism using data surface servo, a sufficient output from the recording track can be obtained during reproduction due to a deviation between the recording track position and the reproduction track position. This results in a phenomenon that the defect inspection measurement cannot be performed.
[0010]
Further, since the recording track position and the reproduction track position are shifted, reproduction of the edge portion of the recording track causes a problem that a place other than the defect existing on the magnetic disk is detected as a defect.
[0011]
An object of the present invention is to provide an inspection method capable of inspecting minute defects in a reproducing head having a narrow track.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, a magnetic disk signal for inspecting a magnetic disk for signal defects using a composite inspection magnetic head in which a thin film magnetic head for recording and a thin film magnetic head for reproduction are integrated. In the defect inspection method, the inspection magnetic head has an element width of the recording thin film magnetic head of 2.12 times or more of the element width of the reproduction thin film magnetic head, and is smaller than the element width of the reproduction thin film magnetic head. Inspect the magnetic disk with a thin film magnetic head for recording, using a thin film magnetic head for recording that has a larger element width ratio than the corresponding element width ratio of the magnetic head of the magnetic disk drive that will use the magnetic disk. The recording pattern for inspection is recorded on the circumference of one track to be reproduced, reproduced by the thin film magnetic head for reproduction, and then inspected on the circumference of the next track to be inspected by the thin film magnetic head for recording. The recording pattern was recorded, it sequentially repeats the operation of reproducing a thin film magnetic head for reproduction, checking the signals of each track reproduced by the thin-film magnetic head for reproduction. The reason will be described below.
[0014]
First, in the defect inspection of a magnetic disk, an inspection recording pattern for one round is recorded on one track and reproduced to detect abnormalities such as signal loss and to know the signal defect. . Next, when inspecting the next track, the inspection pattern of the previous track has been written, but it is only necessary to overwrite the track and erase the previous inspection pattern before inspection. Therefore, the previous inspection pattern does not affect anything. Here, although the recording pattern of the previous track is erased by the recording pattern written for the inspection of the track, it does not need to remain, so there is no problem. That is, as described above, even if the inspection pattern is recorded with a wide recording track width that is not used in an actual magnetic disk device, there is no problem when the purpose is to inspect the defect of the magnetic disk.
[0015]
On the other hand, the playback output is as follows.
[0016]
FIG. 5 shows an output reproduced by a magnetic head having an MR element having a narrow reproduction track width after recording with a recording element portion having a wide recording track width of the present invention, and the conventional recording track width and reproduction track width are substantially equal. The result measured by moving (offset) the output reproduced by the magnetic head in the radial direction during reproduction is shown.
[0017]
It can be seen that when the conventional magnetic head is used, the reproduction output rapidly increases and decreases with respect to the radial position, whereas when the magnetic head of the present invention is used, the change has a relatively gradual region. That is, when the conventional magnetic head is used, if the position of the recording element portion and the reproducing MR element portion is even slightly shifted, the output decreases rapidly, making it difficult to discriminate between noise and defects, which hinders defect inspection. Come.
[0018]
On the other hand, in the case of the present invention, it is understood that a slight misalignment between the recording element and the reproducing MR element portion is acceptable. Furthermore, the present inventor has to make the width of the recording element portion more than twice the width of the reproducing MR element portion in order to make such a relatively gentle area with a sufficient width in the magnetic head of the present invention. I found a good thing.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a magnetic head according to an embodiment of the present invention will be described. An enlarged view of a magnetic head element portion showing an embodiment of the present invention is shown in FIG. FIG. 2 shows a positional relationship model diagram of the recording / reproducing elements of the magnetic head of this embodiment. 1 and 2, 11 is an upper magnetic film made of CoNiFe or the like, 12 is a coil made of Cu or Cr, 13 is an upper shield film / lower magnetic film made of NiFeN, or the like, and 14 is made of Nb, Au, Nb, or the like. 15 is an MR sensor film made of NiFe or the like, 16 is a magnetic domain control film made of NiO or the like, and 17 is a lower shield film made of NiFeN or the like. Any film is formed by sputtering or the like. In addition, the constituent parts of each film are summarized, wherein 01 is a recording element and 02 is a magnetic flux sensing part of a reproducing element. In FIG. 2, a is the element width of the recording head, and b is the element width of the reproducing head.
[0020]
As shown in FIG. 2, the width a of the recording element 01 is 1.80 μm, the width b of the reproducing element 02 is 0.85, and the width a of the recording element 01 is 2.12 times the reproducing element width b. And a width of 1.5 times or more.
[0021]
As a comparison with the magnetic head of this embodiment, FIG. 3 shows a positional relationship model diagram of recording / reproducing elements of a magnetic head using a conventional technique. As shown in FIG. 3, the width a of the recording element 01 is 1.35 μm, the width b of the reproducing element 02 is 0.95, and the width a of the recording element 01 is 1.42 times the reproducing element width b. And a width of 1.5 times or less.
[0022]
FIG. 4 shows an assembly diagram of the magnetic head according to the present embodiment and the magnetic head using the prior art. In FIG. 4, reference numeral 41 denotes a magnetic head provided with the magnetic head element, which is processed into a slider. Reference numeral 42 denotes a suspension on which the slider 41 is mounted and elastically supported.
[0023]
In this embodiment, the magnetic head of the present invention shown in FIG. 2 is used for defect inspection of a magnetic disk. For comparison, the prior art magnetic head of FIG. 3 was used for defect inspection of the same magnetic disk. In the defect inspection measurement, a high-frequency signal is first written on a predetermined track of the magnetic disk by the recording element 01, and then the average read voltage of one track is measured by the reproducing element 02. If there is a defect location that hinders recording / reproduction in a predetermined track, it is observed as a modulation error, missing error, extra error, spike error, or the like.
[0024]
If an error is measured, the high frequency signal is written again to a predetermined track of the magnetic disk by the recording element 01, and then the average read voltage for one round of the track is measured by the reproducing element 02. As described above, when an error is also determined by the error measurement (retry operation) again, it is counted as an error. By performing this measurement within a specified range of the magnetic disk, the total number of defects on the magnetic disk is determined.
[0025]
FIG. 5 shows offset profiles of the magnetic head of the present invention and the conventional magnetic head. Here, the offset profile is the result of measuring the output by moving (offset) in the radial direction during reproduction. In FIG. 5, 51 is the offset profile of the magnetic head of the present invention, and 52 is the offset profile of the conventional magnetic head. As shown in FIG. 5, the offset profile of the magnetic head of the present invention shows a wide and gradual change, and it can be seen that there is a sufficient output even at the position of the reproduction track.
[0026]
On the other hand, the offset profile of the conventional magnetic head has a position where the peak value of the reproduction output is different from the recording track position, so the recording track position and the reproduction track position are deviated and the change is steep. I understand. Accordingly, since error measurement is performed at the recording track position, the output at the recording track position of the conventional magnetic head is reduced to 0.195 mVpp. In the defect inspection apparatus used in the present embodiment, when the error measurement output is 0.200 mVpp or less, the S / N is insufficient, the retry operation in error measurement increases, and the measurement time increases.
[0027]
In addition, the reproducibility of the number of detected errors, the defect size, the defect position, etc. deteriorates. In the error measurement using the prior art magnetic head used in this embodiment, the error measurement time is longer than the error measurement using the magnetic head of the present invention. Even when error measurement is repeatedly performed, error measurement using the magnetic head of the present invention has reproducibility of the number of detected errors, defect size, defect position, etc. In the error measurement, the reproducibility of the error measurement result was not recognized, and it was impossible to determine the defect of the magnetic disk in the error measurement.
[0028]
FIG. 6 shows an error map when a defect of a magnetic disk is detected with the magnetic head of the present invention. FIG. 7 shows an error map when a defect of the same magnetic disk is detected by the conventional magnetic head. Comparing FIG. 6 and FIG. 7, it was found that the amount detected as a defect increases when the defect detection of the magnetic disk is performed by the conventional magnetic head. In addition, when defect detection is performed repeatedly, when the defect detection is performed with the magnetic head of the present invention, the measurement is reproducible, whereas when defect detection is performed with the conventional magnetic head, the measurement reproducibility is performed. I found that there was no.
[0029]
Furthermore, when defect analysis was performed on the location where defects were detected with the magnetic head of the present invention, defects such as film peeling were detected, whereas when defect analysis was performed regarding locations where defects were detected with the conventional magnetic head, Nothing was detected. As a result, in the conventional magnetic head, due to the difference between the recording track position and the reproduction track position, the output from the recording track cannot be sufficiently obtained during reproduction, and the S / N is insufficient, and the retry operation in error measurement is performed. It has been found that the measurement time increases due to the increase, and the phenomenon that the defect inspection measurement cannot be reproduced has occurred.
[0030]
Furthermore, since there is a deviation between the recording track position and the reproduction track position, there is a problem that a portion other than a defect existing on the magnetic disk is detected as a defect by reproducing the edge portion of the recording track. I understood.
[0031]
【The invention's effect】
As described above, the magnetic head of the present invention uses a composite thin film magnetic head in which a thin film magnetic head for recording and a thin film magnetic head for reproduction are integrated in a defect inspection apparatus for a magnetic disk. In general, since a thin film magnetic head similar to a magnetic disk device is used, a thin film magnetic head whose recording track width and reproduction track width are narrowed to 2 μm or less as the recording density of the magnetic disk device increases. Since it must be used, due to the difference between the recording track position and the reproduction track position, a sufficient output from the recording track cannot be obtained during reproduction, and a defect inspection measurement cannot be performed.
[0032]
Therefore, by making the recording element width 1.5 times or more the reproducing element width without narrowing the recording element width, the magnetic disk can be inspected for defects even when the track width is 2 μm or less. It becomes possible.
[Brief description of the drawings]
FIG. 1 is an enlarged view of a magnetic head element portion showing an embodiment of the present invention.
FIG. 2 is a model cross-sectional view showing the positional relationship of recording / reproducing elements of the magnetic head of the present embodiment.
FIG. 3 is a model cross-sectional view showing the positional relationship of recording / reproducing elements of a magnetic head using a conventional technique.
FIG. 4 is an assembled perspective view of a magnetic head according to the present embodiment and a magnetic head using a conventional technique.
FIG. 5 is a characteristic diagram showing offset profiles of the magnetic head of the present invention and a conventional magnetic head.
FIG. 6 is an error map when a defect of a magnetic disk is detected with the magnetic head of the present invention.
FIG. 7 is an error map diagram when a defect of a magnetic disk is detected by a conventional magnetic head.
[Explanation of symbols]
01 ... recording element, 02 ... reproducing element, 11 ... upper magnetic film, 12 ... coil,
13 ... upper shield film and lower magnetic film, 14 ... electrode, 15 ... MR sensor film,
16 ... Magnetic domain control film, 17 ... Lower shield film, 41 ... Slider,
42. Suspension.

Claims (1)

In a signal defect inspection method for a magnetic disk, which performs a signal defect inspection on a magnetic disk using a composite inspection magnetic head in which a thin film magnetic head for recording and a thin film magnetic head for reproduction are integrated,
A recording pattern for inspection is recorded on one circumference of one track to be inspected on the magnetic disk by the thin film magnetic head for recording, and is reproduced by the thin film magnetic head for reproduction, and then the thin film magnetic head for recording Then, the recording pattern for inspection is recorded on the circumference of the next track to be inspected, and the operation of reproducing it with the thin film magnetic head for reproduction is sequentially repeated, and the signal of each track reproduced with the thin film magnetic head for reproduction is reproduced. Inspect and
The inspection magnetic head has an element width of the recording thin film magnetic head of 2.12 times or more the element width of the reproducing thin film magnetic head,
The ratio of the element width of the thin film magnetic head for recording to the element width of the thin film magnetic head for reproduction is larger than the ratio of the corresponding element width of the magnetic head of the magnetic disk device that is going to use the magnetic disk. A signal defect inspection method for magnetic disks.

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