JP2002015420A - Defect inspection method for discrete track type magnetic disk medium - Google Patents
Defect inspection method for discrete track type magnetic disk mediumInfo
- Publication number
- JP2002015420A JP2002015420A JP2000192805A JP2000192805A JP2002015420A JP 2002015420 A JP2002015420 A JP 2002015420A JP 2000192805 A JP2000192805 A JP 2000192805A JP 2000192805 A JP2000192805 A JP 2000192805A JP 2002015420 A JP2002015420 A JP 2002015420A
- Authority
- JP
- Japan
- Prior art keywords
- defect inspection
- defect
- width
- reproduction signal
- magnetic disk
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】この発明は、ディスクリート
・トラック型磁気ディスク媒体において、検査用磁気ヘ
ッドの位置決めのためのサーボ制御を行うことなく欠陥
検査を容易に行わせることのできる検査方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection method capable of easily performing a defect inspection on a discrete track type magnetic disk medium without performing servo control for positioning an inspection magnetic head.
【０００２】[0002]
【従来の技術】コンピュータなどに広く用いられている
磁気ディスク装置（ハードディスク装置）では大容量化
に伴ってビット密度のみならずトラック密度も著しく高
くなってきている。2. Description of the Related Art In a magnetic disk device (hard disk device) widely used in computers and the like, not only the bit density but also the track density has been significantly increased with the increase in capacity.
【０００３】この場合、トラック密度の向上のためにト
ラックピッチを狭めるだけではサイドフリンジングなど
の影響で再生信号のＳ／Ｎ比が低下してしまうので、こ
こ１０年程の間に、トラックとトラックとの間を物理的
に分離する溝を形成して信号書込みや消去時の記録ビッ
トや消去幅の広がり現象を防ぐ、いわゆるディスクリー
ト・トラック方式の磁気ディスクが採用されるようにな
ってきた。In this case, if the track pitch is merely reduced to improve the track density, the S / N ratio of the reproduced signal is reduced due to the influence of side fringing or the like. A so-called discrete track type magnetic disk, which forms a groove for physically separating a track and a track to prevent a spread phenomenon of a recording bit and an erase width at the time of signal writing or erasing, has been used.
【０００４】かかる方式の磁気ディスクではトラック密
度を従来方式に比して１０倍以上も高く取れる反面、偏
心などの影響で磁気ヘッドが溝を横切ってしまうと、再
生信号出力が激減して再生不能となるので、磁気ヘッド
の位置決め精度を高くせねばならず、ディスクリート・
トラック方式の磁気ディスク媒体の欠陥検査を行う際に
は、トラッキングサーボを働かせて常にオントラック状
態でリード／ライト検査をする必要がある。[0004] In the magnetic disk of this type, the track density can be at least ten times higher than that of the conventional type, but when the magnetic head crosses the groove due to the eccentricity or the like, the reproduction signal output is drastically reduced and the reproduction becomes impossible. Therefore, it is necessary to increase the positioning accuracy of the magnetic head,
When performing a defect inspection of a track type magnetic disk medium, it is necessary to always perform a read / write inspection in an on-track state by operating a tracking servo.
【０００５】しかしながら、ディスクリート・トラック
方式でない通常の溝無し媒体の欠陥検査ではトラッキン
グサーボをかける必要がなかったので、量産ラインの既
存の欠陥検査装置にはサーボ機能を備えていないものが
多く、このためにかかる検査装置でディスクリート・ト
ラック方式の磁気ディスクの欠陥検査をしようとする
と、検査装置の改造を余儀なくされ、検査コストの増大
を招くという問題が生じる。However, since it is not necessary to apply tracking servo in the defect inspection of a normal non-grooved medium other than the discrete track system, many existing defect inspection apparatuses in mass production lines do not have a servo function. Therefore, if the inspection apparatus attempts to inspect the magnetic disk of the discrete track system for defects, the inspection apparatus must be remodeled and the inspection cost increases.
【０００６】[0006]
【発明が解決しようとする課題】そこで、この発明の課
題は、ディスクリート・トラック方式の磁気ディスクの
欠陥検査を行うに当たり、サーボ制御を行うことなしに
検査を実行できる方法を提供することにある。SUMMARY OF THE INVENTION An object of the present invention is to provide a method for performing a defect inspection of a discrete track type magnetic disk without performing servo control.
【０００７】[0007]
【課題を解決するための手段】この課題を解決するため
に、請求項１の発明では、図１に示すような２トラック
以上にまたがる幅広のヘッド１を用いて検査を行う。In order to solve this problem, according to the first aspect of the present invention, an inspection is performed using a wide head 1 extending over two or more tracks as shown in FIG.
【０００８】図２に示すようにサーボをかけないで通常
の狭幅のヘッド２を用いると、図２（Ａ）のごとくヘッ
ド２がトラックの上に位置しているときは良いが、偏心
の影響で図２（Ｂ）のごとくヘッド２がオフトラックし
てしまうと、再生信号のレベルは図３（Ａ）に示すよう
に著しく低下してしまう。As shown in FIG. 2, when a normal narrow head 2 is used without servo control, it is good when the head 2 is positioned on a track as shown in FIG. When the head 2 goes off-track as shown in FIG. 2B due to the influence, the level of the reproduced signal is significantly reduced as shown in FIG. 3A.
【０００９】それに対し、幅広のヘッドを用いれば、サ
ーボをかけなくてもヘッドの下には図１（Ｂ）に示すよ
うに常に１トラック以上が存在することになるので、図
３（Ｂ）に示すような検出可能レベルの再生信号が得ら
れる。On the other hand, if a wide head is used, one or more tracks always exist under the head as shown in FIG. 1B even without servo control. A reproduced signal having a detectable level as shown in FIG.
【００１０】なお、ディスクリート・トラック方式の磁
気ヘッドの幅を、記録部の幅より幅広とすることは、た
とえば特開平１０−１０５９６１号により知られてい
る。しかしながら、この公知の技術は記録部の全面にわ
たって記録を行うために記録部幅以上の幅を持つ磁気ヘ
ッドを使用することを提案しているもので、欠陥検査に
ついては触れるところがなく、磁気ヘッドの幅もたかだ
か１トラックピッチであり、しかも通常の記録再生操作
を念頭においているため、磁気ヘッドの位置決めのため
のサーボ制御は当然のごとくかけることを前提としてい
る。It is known, for example, from Japanese Patent Application Laid-Open No. 10-105961, that the width of the magnetic head of the discrete track system is made wider than the width of the recording section. However, this known technique proposes to use a magnetic head having a width equal to or greater than the width of the recording section in order to perform recording over the entire recording section, and there is no mention of defect inspection. Since the width is at most one track pitch and a normal recording / reproducing operation is taken into consideration, it is assumed that servo control for positioning the magnetic head is performed as a matter of course.
【００１１】これに対して、本発明は、磁気ディスク通
常の記録再生操作ではなく、工場出荷前の欠陥検査に対
処するものであり、また磁気ヘッドの記録幅も、より厳
密にいうならば、ディスクリート・トラック方式の磁気
ディスクにおいて、溝部の幅と溝部以外の記録部の幅と
の和をトラックピッチと呼んだ場合に、幅広ヘッドの幅
は、トラックピッチの２倍から溝部の幅を減じた幅以上
の幅を有する必要がある。On the other hand, the present invention deals with a defect inspection before shipment from a factory instead of a normal recording / reproducing operation of a magnetic disk, and the recording width of a magnetic head is more strictly speaking. In the magnetic disk of the discrete track system, when the sum of the width of the groove and the width of the recording portion other than the groove is called a track pitch, the width of the wide head is obtained by subtracting the width of the groove from twice the track pitch. It must have a width equal to or greater than the width.
【００１２】本発明を実施する場合に、ヘッドの幅をｎ
トラック分カバーできる幅に増せば、ヘッドの下には常
にｎ−１トラック以上が存在することになるので、オフ
トラックによるレベルダウンの影響が１／ｎに緩和され
た再生信号を得ることが可能である。In practicing the present invention, the width of the head is set to n.
If the width is increased to cover the number of tracks, there will always be n-1 tracks or more under the head, so that it is possible to obtain a reproduction signal in which the effect of the level down due to off-track is reduced to 1 / n. It is.
【００１３】また、再生信号のレベル変動として現れて
くる偏心に起因した信号成分の周期は記録信号の周期に
比べてかなり長いので、幅広のヘッドにより得られた再
生信号からハイパスフィルタにより低周波成分（偏心の
影響分）をカットすれば安定した再生信号を得ることが
できる。（請求項２の発明）。Further, since the cycle of the signal component caused by the eccentricity which appears as the level fluctuation of the reproduction signal is considerably longer than the cycle of the recording signal, the low-frequency component is obtained from the reproduction signal obtained by the wide head by the high-pass filter. By cutting (influence of eccentricity), a stable reproduced signal can be obtained. (Invention of claim 2).
【００１４】フィルタを用いるかわりに再生信号の増幅
器にＡＧＣ（自動利得制御）をかけて安定した再生信号
を得ることも可能である（請求項３の発明）。Instead of using a filter, it is also possible to obtain a stable reproduced signal by applying AGC (automatic gain control) to the amplifier of the reproduced signal (invention 3).
【００１５】欠陥検出は、このようにして得られた再生
信号において著しく信号レベルの低い個所を検出するこ
とにより行う。これは通常の磁気ディスクの欠陥検査と
同じであり、既存の検査装置の改造は必要でない。The defect detection is performed by detecting a portion where the signal level is extremely low in the reproduced signal thus obtained. This is the same as a normal magnetic disk defect inspection, and does not require modification of an existing inspection device.
【００１６】磁気ヘッドの幅を広くしてカバーできるト
ラック数を大きくすればするほどヘッドのオフトラック
の影響をよく緩和できるが、小さな欠陥に対する反応も
同時に緩和されて小さくなる（欠陥に対する再生信号の
変動の大きさが低下する）ので、ヘッドの幅は検査対象
の磁気ディスクに許容される欠陥の大きさを考慮して決
定する。The effect of the off-track of the head can be better mitigated by increasing the number of tracks that can be covered by increasing the width of the magnetic head. Therefore, the width of the head is determined in consideration of the size of a defect allowed for the magnetic disk to be inspected.
【００１７】[0017]
【発明の実施の形態】図４にこの発明の実施例を示す。
４トラック分をカバーする幅の磁気ヘッドにより、信号
を書きこんで再生する。再生信号のピークを検出し、図
５に示すように予め決められた閾値Ｖｔｈと比較し、閾
値以下の値であればその個所を欠陥として認識する。閾
値Ｖｔｈは、ヘッドがオフトラックしてレベル低下した
ときの再生信号よりも低い値に決定する必要がある。FIG. 4 shows an embodiment of the present invention.
A signal is written and reproduced by a magnetic head having a width covering four tracks. The peak of the reproduction signal is detected and compared with a predetermined threshold value Vth as shown in FIG. 5, and if the value is equal to or smaller than the threshold value, the point is recognized as a defect. The threshold value Vth needs to be determined to be lower than the value of the reproduction signal when the head is off-track and the level is lowered.
【００１８】実際の検査方法としては、図６に示すよう
に、仮に磁気ディスク媒体の各トラックに内周側から外
周側に順に１、２、３、・・・と番号を付けたとする
と、先ず、図６（Ａ）に示す位置に磁気ヘッド（幅Ｘ）
が位置しているときに領域Ａのトラック１〜４の欠陥検
査を行なう。これが完了したら、検出された欠陥情報
（位置、大きさなど）を記憶しておいて、次に図６
（Ｂ）に示すようにヘッドの位置をＸだけ移動させ、領
域Ｂのトラック５〜８の検査に移る。As an actual inspection method, as shown in FIG. 6, if each track of the magnetic disk medium is numbered 1, 2, 3,... And a magnetic head (width X) at the position shown in FIG.
Is located, tracks 1 to 4 in area A are inspected for defects. When this is completed, the detected defect information (position, size, etc.) is stored, and FIG.
As shown in (B), the position of the head is moved by X, and the inspection of tracks 5 to 8 in the area B is started.
【００１９】例としてあげた領域Ａ、Ｂはディスクの円
周に沿うそれぞれ幅Ｘの領域であり、ディスクの偏心な
どの影響により常にトラック１〜４ないしは５〜８のみ
をカバーしているとは限らないが、本発明による欠陥検
査はトラックを特定して行なうものではなく、要は全面
を検査できればよいのであるから、ヘッドを正確にＸだ
け移動させることができればそれで十分である。The regions A and B given as examples are regions having a width X along the circumference of the disk, and always cover only the tracks 1 to 4 or 5 to 8 due to the eccentricity of the disk. Although not limited, the defect inspection according to the present invention is not performed by specifying a track, but it is only necessary to inspect the entire surface. Therefore, it is sufficient if the head can be moved exactly by X.
【００２０】もちろん、ヘッドの移動量をヘッドの幅Ｘ
より所定幅αだけ少なく設定して検査領域を重複させる
ことによりいわゆる冗長検査を行なって検査漏れを少な
くすることも可能である。Of course, the amount of movement of the head is determined by the width X of the head.
It is also possible to reduce inspection omissions by performing a so-called redundancy inspection by setting inspection widths smaller by a predetermined width α and overlapping inspection regions.
【００２１】以下同様にしディスク全面の検査を行い、
ディスク全面分の欠陥情報をもとに検査対象ディスク媒
体に対して最終的な良品／不良品の判定を下す。In the same manner, inspection of the entire surface of the disk is performed.
Based on the defect information for the entire surface of the disk, a final good / defective determination is made for the disk medium to be inspected.
【００２２】図７は本発明の異なる実施例の出力波形図
を示すもので、再生信号のビート状包絡線が主として偏
心の影響によることに着目し、再生信号中の低周波成分
をハイパスフィルタでカットするか、あるいは再生信号
の増幅器にＡＧＣをかけて安定した再生信号を得ようと
するものである。FIG. 7 shows an output waveform diagram of a different embodiment of the present invention. Paying attention to the fact that the beat-like envelope of the reproduced signal is mainly affected by the eccentricity, a low-frequency component in the reproduced signal is filtered by a high-pass filter. It is intended to cut or to perform AGC on the amplifier of the reproduction signal to obtain a stable reproduction signal.
【００２３】[0023]
【発明の効果】本発明によれば、欠陥検査にあたって検
査用磁気ヘッドの位置決めのためにサーボをかける必要
がないので、既存の製造ラインの欠陥検査装置でディス
クリート・トラック型磁気ディスク媒体の欠陥検査が可
能となるとともに、数トラック分を一度に検査するの
で、全面を検査する時間が短縮され検査スループットの
向上が図れるという利点がある。According to the present invention, it is not necessary to apply a servo for positioning the magnetic head for inspection at the time of defect inspection. Therefore, the defect inspection of the discrete track type magnetic disk medium can be performed by the defect inspection apparatus of the existing production line. In addition, since several tracks are inspected at once, there is an advantage that the time required to inspect the entire surface can be reduced and the inspection throughput can be improved.
【図１】この発明の実施例の断面図。FIG. 1 is a sectional view of an embodiment of the present invention.
【図２】従来例の断面図。FIG. 2 is a sectional view of a conventional example.
【図３】従来例と本発明実施例との再生信号の比較図。FIG. 3 is a comparison diagram of a reproduction signal between a conventional example and an embodiment of the present invention.
【図４】この発明の実施例の平面図および断面図。FIG. 4 is a plan view and a sectional view of an embodiment of the present invention.
【図５】この発明の他の実施例の出力信号波形図。FIG. 5 is an output signal waveform diagram of another embodiment of the present invention.
【図６】本発明の実施例のトラックとヘッドとの関係を
示す平面図。FIG. 6 is a plan view showing a relationship between a track and a head according to the embodiment of the present invention.
【図７】本発明の他の実施例の出力信号波形図。FIG. 7 is an output signal waveform diagram according to another embodiment of the present invention.
１・・・幅広ヘッド、 ２・・・溝、 ３・・・トラック、 ４・・・通常の磁気ヘッド ５・・・磁気ディスク DESCRIPTION OF SYMBOLS 1 ... Wide head, 2 ... Groove, 3 ... Track, 4 ... Normal magnetic head 5 ... Magnetic disk
Claims (4)
ク媒体の欠陥を検査する際に、トラックピッチに対して
幅広の磁気ヘッドを用いることによりサーボ制御を行う
ことなしに検査を行うことを特徴とするディスクリート
・トラック型磁気ディスク媒体の欠陥検査方法。1. A method for inspecting a defect of a discrete track type magnetic disk medium, wherein the inspection is performed without performing servo control by using a magnetic head having a width larger than a track pitch. Defect inspection method for track type magnetic disk media.
前記幅広の磁気ヘッドとしてトラックピッチの２倍から
溝部の幅を減じた幅以上の幅を有するヘッドを用いたこ
とを特徴とするディスクリート・トラック型磁気ディス
ク媒体の欠陥検査方法。2. The defect inspection method according to claim 1, wherein
A defect inspection method for a discrete track type magnetic disk medium, characterized in that a head having a width equal to or greater than twice the track pitch and the width of the groove is used as the wide magnetic head.
おいて、前記幅広の磁気ヘッドから得られる再生信号に
対して、ハイパスフィルタにより低周波の信号成分をカ
ットすることによって振幅変動の少ない再生信号を形成
し、この再生信号に基づいて欠陥検査を行うことを特徴
とするディスクリート・トラック型磁気ディスク媒体の
欠陥検査方法。3. The defect inspection method according to claim 1, wherein a low-frequency signal component is cut by a high-pass filter from the reproduction signal obtained from the wide magnetic head to thereby reduce the amplitude fluctuation. And a defect inspection method for a discrete track type magnetic disk medium, wherein the defect inspection is performed based on the reproduced signal.
おいて、前記幅広の磁気ヘッドから得られる再生信号の
増幅器に自動利得制御をかけることによって振幅変動の
少ない再生信号を形成し、この再生信号に基づいて欠陥
検査を行うことを特徴とするディスクリート・トラック
型磁気ディスク媒体の欠陥検査方法。4. The defect inspection method according to claim 1, wherein a reproduction signal having a small amplitude fluctuation is formed by performing automatic gain control on an amplifier of the reproduction signal obtained from said wide magnetic head. A defect inspection method for a discrete track type magnetic disk medium, wherein the defect inspection is performed based on the following.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000192805A JP2002015420A (en) | 2000-06-27 | 2000-06-27 | Defect inspection method for discrete track type magnetic disk medium |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000192805A JP2002015420A (en) | 2000-06-27 | 2000-06-27 | Defect inspection method for discrete track type magnetic disk medium |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2002015420A true JP2002015420A (en) | 2002-01-18 |
Family
ID=18691885
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2000192805A Pending JP2002015420A (en) | 2000-06-27 | 2000-06-27 | Defect inspection method for discrete track type magnetic disk medium |
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| Country | Link |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009259375A (en) * | 2008-03-25 | 2009-11-05 | Fuji Electric Device Technology Co Ltd | Patterned medium inspection method and inspection device |
| US7623311B2 (en) | 2005-03-18 | 2009-11-24 | Kabushiki Kaisha Toshiba | Recording media, recording and reproducing apparatus, and method for recording and reproducing |
| US7746587B2 (en) | 2006-03-06 | 2010-06-29 | Kabushiki Kaisha Toshiba | Magnetic recording apparatus and magnetic recording and reproducing apparatus |
-
2000
- 2000-06-27 JP JP2000192805A patent/JP2002015420A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7623311B2 (en) | 2005-03-18 | 2009-11-24 | Kabushiki Kaisha Toshiba | Recording media, recording and reproducing apparatus, and method for recording and reproducing |
| US7746587B2 (en) | 2006-03-06 | 2010-06-29 | Kabushiki Kaisha Toshiba | Magnetic recording apparatus and magnetic recording and reproducing apparatus |
| JP2009259375A (en) * | 2008-03-25 | 2009-11-05 | Fuji Electric Device Technology Co Ltd | Patterned medium inspection method and inspection device |
| US8023213B2 (en) | 2008-03-25 | 2011-09-20 | Fuji Electric Device Technology Co., Ltd | Patterned medium inspection method and inspection device |
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