JPS60186768A - Measuring device for coercive force - Google Patents

Measuring device for coercive force

Info

Publication number
JPS60186768A
JPS60186768A JP4332484A JP4332484A JPS60186768A JP S60186768 A JPS60186768 A JP S60186768A JP 4332484 A JP4332484 A JP 4332484A JP 4332484 A JP4332484 A JP 4332484A JP S60186768 A JPS60186768 A JP S60186768A
Authority
JP
Japan
Prior art keywords
light
coercive force
magnetic field
medium
recording medium
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.)
Granted
Application number
JP4332484A
Other languages
Japanese (ja)
Other versions
JPH0646215B2 (en
Inventor
Kiyoshi Uchida
清 内田
Masahiro Orukawa
正博 尾留川
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Panasonic Holdings Corp
Original Assignee
Matsushita Electric Industrial Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Priority to JP4332484A priority Critical patent/JPH0646215B2/en
Publication of JPS60186768A publication Critical patent/JPS60186768A/en
Publication of JPH0646215B2 publication Critical patent/JPH0646215B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/12—Measuring magnetic properties of articles or specimens of solids or fluids
    • G01R33/14—Measuring or plotting hysteresis curves

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  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Magnetic Variables (AREA)

Abstract

PURPOSE:To measure the coercive force distribution of a photomagnetic recording medium in a short time by using magnetic field applying elements arranged across the photomagnetic recording medium and measuring the coercive force by utilizing the magnetooptic effect of light converged by a cylindrical lens. CONSTITUTION:The photomagnetic recording medium 19 is moved by a rotating machine 21 in a magnetic field established with the magnetic field applying elements 15 and 16. On the other hand, laser light which is converged by the cylindrical lens 14 and sectioned elliptically is made incident through a half- mirror 5 and reflected laser light or transmitted laser light under the influence of hysteresis-free magnetooptic effect corresponding to the coercive force of the medium 19 which varies according to the long-axis position of the ellipse is photodetected by a photodetector 17 or 23. The magnetooptic effect which does not draw a hysteresis curve eliminates the need to stop the medium 19 and apply a low-frequency alternating magnetic field, and the coercive force distribution of the photomagnetic recording medium is measured in a short time.

Description

【発明の詳細な説明】 産業上の利用分野 本発明は磁気光学効果を利用した保磁力測定装置に関す
るものである。DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a coercive force measuring device that utilizes the magneto-optical effect.

従来例の構成とその問題点 近年、光磁気ディスクは書き換え可能な大容量記録媒体
として注目され、精力的に研究・開発が行われてきてい
る。光磁気記録媒体（以下媒体と略す）の保磁力は媒体
の特性の中で最も重要なパラメータの一つであり、媒体
の記録領域上の微少部分の保磁力を広範囲にわたって測
定する必要がある。Conventional Structures and Problems In recent years, magneto-optical disks have attracted attention as rewritable large-capacity recording media, and have been actively researched and developed. The coercive force of a magneto-optical recording medium (hereinafter abbreviated as medium) is one of the most important parameters among the characteristics of the medium, and it is necessary to measure the coercive force of minute portions on the recording area of the medium over a wide range.

第１図は、光磁気光学効果を利用した、従来の保磁力測
定装置の構成図である。FIG. 1 is a block diagram of a conventional coercive force measuring device that utilizes the magneto-optical effect.

第１図において、１はガスレーザ、半導体レーザ等の光
源、２は偏光子、３はフォトダイオード、光電子増倍管
等の受光器、４は検光子、５はハーフミラ−１６は対物
レンズ、７Ｆｉ、マグネットコイル、８はホール素子等
の磁界検出素子、９は光磁気記録媒体、１ｏは検光子４
と同じ動作、作用効果を持つ検光子、１１は受光器３と
同じ動作、作用効果を持つ受光器、１２．１３はそれぞ
れ受光器３，１１の出力をＹ＠に、磁界検出素子８の出
力をＸ軸に表示できる表示装置である。In FIG. 1, 1 is a light source such as a gas laser or semiconductor laser, 2 is a polarizer, 3 is a photoreceiver such as a photodiode or photomultiplier tube, 4 is an analyzer, 5 is a half mirror, 16 is an objective lens, 7Fi, A magnet coil, 8 a magnetic field detection element such as a Hall element, 9 a magneto-optical recording medium, 1o an analyzer 4
11 is a photoreceiver with the same operation and effect as photoreceiver 3, 12.13 is the output of photoreceiver 3 and 11 as Y@, and the output of magnetic field detection element 8. This is a display device that can display on the X axis.

以下に第１図で示した構成で媒体の保磁力を測定する方
法を述べる。A method for measuring the coercive force of a medium using the configuration shown in FIG. 1 will be described below.

光源１を出た光は偏光子２を通過後、直線偏光面を有す
る光となる。この光は八−フミラー６によって、媒体９
の方向に反射される。After the light emitted from the light source 1 passes through the polarizer 2, it becomes light having a linearly polarized plane. This light is transmitted to a medium 9 by an eight-frame mirror 6.
reflected in the direction of

媒体９がこの光に対して反射性を有する場合には、光は
光磁気記録媒体９で反射され、検光子４を通過し、受光
器３に達する。受光器３は光の量に対応した信号を表示
装置１２に送る。If the medium 9 has a reflective property for this light, the light is reflected by the magneto-optical recording medium 9, passes through the analyzer 4, and reaches the light receiver 3. The light receiver 3 sends a signal corresponding to the amount of light to the display device 12.

また、媒体９がこの光に対して透過性を有する場合には
、光は光磁気記録媒体９を透過し、検光子１０を介して
、受光器１１に達する。受光器１１は光の量に対応した
信号を表示装置１３に送る。If the medium 9 is transparent to this light, the light passes through the magneto-optical recording medium 9 and reaches the light receiver 11 via the analyzer 10. The light receiver 11 sends a signal corresponding to the amount of light to the display device 13.

マクネットコイル７にょ９媒体９の受光面に交番磁界を
印加することにより、検光子４又は１０を通過する光量
が変化する。磁界の変化を磁界検出素子８により、又光
量の変化を受光素子３又は１１によって検出し、表示装
置１２又は１３に、カーヒステリシス曲線、又はファラ
デーヒステリシス曲線を描いて、保磁力を表示する。By applying an alternating magnetic field to the light-receiving surface of the Macnet coil 7 and medium 9, the amount of light passing through the analyzer 4 or 10 changes. Changes in the magnetic field are detected by the magnetic field detection element 8 and changes in the amount of light are detected by the light receiving element 3 or 11, and a Kerr hysteresis curve or a Faraday hysteresis curve is drawn on the display device 12 or 13 to display the coercive force.

さて、第１図に示した従来例の構成を利用して保磁力を
測定する場合、ヒステリシス曲線を描くためには、媒体
９を静止してきわめて低い周波数の交番磁界を印加する
必要がある。直径１２〜３０ｔｙｎ　（Ｄ　光磁気ディ
スクの保磁力を数十平方ミクロンの微少面積について測
定し、光磁気ディスクの全記録領域にわたって保磁力分
布をめる必要がある場合には、上記従来例の構成では、
短時間に測定することができないという問題点を有して
いた。Now, when measuring the coercive force using the conventional configuration shown in FIG. 1, in order to draw a hysteresis curve, it is necessary to keep the medium 9 stationary and apply an alternating magnetic field at an extremely low frequency. Diameter: 12 to 30 tyn So,
The problem was that measurements could not be taken in a short period of time.

発明の目的 本発明は上記従来の問題点を解消するもので、光磁気記
録媒体の保磁力分布測定を短時間に行い得る保磁力測定
装置を提供することを目的とする。OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional problems, and it is an object of the present invention to provide a coercive force measuring device that can measure the coercive force distribution of a magneto-optical recording medium in a short time.

発明の構成 本発明は、レーザ等の光源からの光を集光するシリンド
リカルレンズと、前記シリンドリカルレンズからの光を
透過又は反射してなる光磁気記録媒体と、前記光が透過
又は反射される前記光磁気記録媒体部分に磁界を印加し
かつ前記光磁気記録媒体を挾むように設けられた複数個
の磁界印加素子と、前記光磁気記録媒体を回転可能に駆
動する駆動装置と、前記光磁気記録媒体の透過又は反射
光を受光する複数個の受光素子を有する受光器とを備え
た構成と々っており、これにより保磁力分布を短時間に
測定することができる。Structure of the Invention The present invention provides a cylindrical lens that condenses light from a light source such as a laser, a magneto-optical recording medium that transmits or reflects the light from the cylindrical lens, and a magneto-optical recording medium that transmits or reflects the light. A plurality of magnetic field applying elements that apply a magnetic field to a magneto-optical recording medium portion and are provided to sandwich the magneto-optical recording medium, a drive device that rotatably drives the magneto-optical recording medium, and the magneto-optical recording medium. The structure includes a light receiver having a plurality of light-receiving elements that receive transmitted or reflected light, and thereby the coercive force distribution can be measured in a short time.

実施例の説明 本発明の実施例について図面にもとづいて説明する。第
２図は本発明の一実施例における保磁力測定装置の概略
構成図である。第２図において第１図と同一部材には同
一番号を付し説明を省略する。１４は光を長楕円形に集
光するシリンドリカルレンズ、１５．１６は磁界印加素
子であって、光が透過できる部分を有し、同一磁極を向
は合い偏芯配置と々っている。１７はシリンドリカルレ
ンズ１４が形成する長楕円光の長手方向に一直線に並ん
だ受光素子群を有する受光器、１８は受光器１７からの
信号を表示する表示装置である。DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described based on the drawings. FIG. 2 is a schematic configuration diagram of a coercive force measuring device according to an embodiment of the present invention. In FIG. 2, the same members as those in FIG. 1 are given the same numbers and their explanations will be omitted. 14 is a cylindrical lens that condenses light into an oblong shape, and 15 and 16 are magnetic field applying elements, which have a portion through which light can pass, and have the same magnetic poles facing each other and arranged eccentrically. 17 is a light receiver having a group of light receiving elements arranged in a straight line in the longitudinal direction of the long elliptical light formed by the cylindrical lens 14; 18 is a display device for displaying the signal from the light receiver 17;

１ず、光源１を出た光は偏光子２で直線偏光となり、シ
リンドリカルレンズ１４を通過し、長楕円形の断面を有
する光となる。この光は磁界印加素子１６．１６の内空
間を通り検光子４を通過し受光器１７に入射する。First, the light emitted from the light source 1 becomes linearly polarized light by the polarizer 2, passes through the cylindrical lens 14, and becomes light having an oblong cross section. This light passes through the inner space of the magnetic field applying element 16, 16, passes through the analyzer 4, and enters the light receiver 17.

第２図において、磁界印加素子１５と１６の間には」二
下方向に磁界が印加されており、長楕円形の光の長手方
向すなわち受光素子の並びの方向に、磁界の大きさと方
向が第３図に示すように変化している。第２図に示した
構成は媒体の透過光を用いたファラデー効果を利用した
ものであるが、反射光を用いたカー効果を利用した測定
でも利用できる。In FIG. 2, a magnetic field is applied between the magnetic field applying elements 15 and 16 in the downward direction, and the magnitude and direction of the magnetic field are in the longitudinal direction of the oblong light, that is, in the direction of the arrangement of the light receiving elements. It changes as shown in Figure 3. Although the configuration shown in FIG. 2 utilizes the Faraday effect using light transmitted through the medium, it can also be used for measurement using the Kerr effect using reflected light.

保磁力測定の方法を以下に説明する。The method of measuring coercive force will be explained below.

媒体を磁界印加素子１５と１６の間の空間に配し、楕円
光の長手方向に移動させる。媒体上の任意の点に注目す
ると、この点は磁界印加素子１５と１６の間の空間を通
過する際に、第３図に示しだ磁界を被る。媒体上のこの
点の保磁力がＨ３（Ｈ。A medium is placed in the space between the magnetic field applying elements 15 and 16 and moved in the longitudinal direction of the elliptical light. When focusing on an arbitrary point on the medium, this point is subjected to a magnetic field as shown in FIG. 3 when passing through the space between the magnetic field applying elements 15 and 16. The coercive force at this point on the medium is H3 (H.

〈Ｈｍａｘ）であるとすると、この点は最初上向きの磁
界Ｈｍａｘを受け、移動に伴って連続的に小さくなる磁
界を受ける。そして、ある場所で下向きの磁界を受ける
ようになり、移動に伴って連続的に大きくなり下向きの
磁界Ｈｍａｘまで達する磁界を受ける。この点の磁化は
大きさＨＣの下向きの磁界を受けた時に反転する。磁化
の反転により、媒体のファラデー回転角の方向が逆転す
るため検光子４を通過する光量が変化する。Assuming that <Hmax), this point initially receives an upward magnetic field Hmax, and receives a magnetic field that continuously decreases as it moves. Then, it begins to receive a downward magnetic field at a certain location, and as it moves, it receives a magnetic field that continuously increases until it reaches the downward magnetic field Hmax. The magnetization at this point is reversed when subjected to a downward magnetic field of magnitude HC. Due to the reversal of magnetization, the direction of the Faraday rotation angle of the medium is reversed, so the amount of light passing through the analyzer 4 changes.

楕円光の長手方向の磁界分布が既知であれば、受光器１
７の各受光素子に入る入射光の量が、どの受光素子を境
にして変化しているかが判明すれば、磁界印加素子１６
と１６の間を通過する媒体の保磁力を知ることができる
。If the longitudinal magnetic field distribution of the elliptical light is known, the receiver 1
If it is known at which light receiving element the amount of incident light entering each light receiving element 7 changes, the magnetic field applying element 16
The coercive force of the medium passing between and 16 can be determined.

第４図は本発明の一実施例における保磁力測定装置の構
成図である。FIG. 4 is a configuration diagram of a coercive force measuring device in an embodiment of the present invention.

第４図において、第１図、第２図と同一部材には同一番
号を付し説明を省略する。第４図において、１９は円板
形状の光磁気記録媒体で、例えば示装置、２１は媒体１
９を回転するための回転機、２２は受光器１７と同じ動
作、作用効果を有する受光器２３からの信号を表示する
ための表示装置である。In FIG. 4, the same members as those in FIGS. 1 and 2 are given the same numbers and their explanations will be omitted. In FIG. 4, 19 is a disk-shaped magneto-optical recording medium, for example, a display device, 21 is a medium 1
22 is a display device for displaying the signal from the light receiver 23, which has the same operation and effect as the light receiver 17.

尚、上記構成の保磁力測定装置は、媒体１９が光透過型
の光磁気記録媒体でも反射型の光磁気記録媒体でも測定
できるように受光器等を２ケ所に設けているが、媒体１
９の種類に応じて一方のみの構成にしてもよいことは言
うまでもない。The coercive force measuring device having the above configuration is equipped with light receivers and the like at two locations so that it can measure whether the medium 19 is a light transmission type magneto-optical recording medium or a reflective type magneto-optical recording medium.
It goes without saying that only one of the configurations may be used depending on the type of 9.

以上のように構成された本実施例の保磁力測定装置につ
いて、以下にその動作を説明する。The operation of the coercive force measuring device of this embodiment configured as described above will be explained below.

光源１を出た光は偏光子２によって直線偏光面を有する
光となる。この光はシリンドリカルレンズ４を通過後、
長楕円形の断面を有する光となる。The light emitted from the light source 1 is turned into light having a linearly polarized plane by the polarizer 2. After this light passes through the cylindrical lens 4,
The light has a long elliptical cross section.

この光はハーフミラ−５によって媒体１９の方向に反射
される。This light is reflected by the half mirror 5 toward the medium 19.

媒体１９がこの光に対して反射性を有する場合には、光
は媒体１９で反射される。この光は検光子４を通過し、
受光器１７に達する。受光器１７はその受光素子群に入
射した光量に応じた信号を表示装置２ｏに送る。If the medium 19 is reflective for this light, the light will be reflected off the medium 19. This light passes through analyzer 4,
The light reaches the light receiver 17. The light receiver 17 sends a signal corresponding to the amount of light incident on the light receiving element group to the display device 2o.

また、媒体１９がこの光に対して透過性を有する場合に
は、光は媒体１９を通過し、検光子１゜を通過して、受
光器２２に達する。受光器２２はその受光素子群に入射
した光量に応じた信号を表示装置２２に送る。If the medium 19 is transparent to this light, the light passes through the medium 19, passes through the analyzer 1°, and reaches the light receiver 22. The light receiver 22 sends a signal to the display device 22 according to the amount of light incident on the light receiving element group.

一方媒体１９は回転機２１により自転し保磁力が測定さ
れる。On the other hand, the medium 19 is rotated by a rotating machine 21 and its coercive force is measured.

本実施例の構成により、まず媒体１９を回転機２１で回
転させながら、−磁区の保磁力を次々に測定していき、
媒体１９に入射する光、並びに磁界印加素子１５．１６
を媒体１９の径方向に動かして、媒体１９の全記録領域
に対して保磁力分布を測定しているので、従来の方法と
同程度の測定精度を確保し、しかもより短時間の測定を
可能としている。With the configuration of this embodiment, first, while the medium 19 is rotated by the rotary machine 21, the coercive force of the -magnetic domain is measured one after another,
Light incident on the medium 19 and magnetic field applying elements 15 and 16
Since the coercive force distribution is measured over the entire recording area of the medium 19 by moving it in the radial direction of the medium 19, the same level of measurement accuracy as the conventional method is ensured, and measurement can be performed in a shorter time. It is said that

尚、媒体１９の全記録領域を測定する場合、光学系又は
磁界印加素子１５．１６を静止させ、媒体１９を径方向
に、動かしてもよい。Note that when measuring the entire recording area of the medium 19, the optical system or the magnetic field application elements 15, 16 may be kept stationary and the medium 19 may be moved in the radial direction.

例えば、半径５０ｍｍから半径１８０咽までの記録領域
を有する媒体１９の保磁力を半径１酬毎に、各測定半径
に対して３ｏ０づつ隔った１２個の測定点、合計１６６
０個の測定点に対して測定した結果、従来例の構成によ
る測定では、全ての測定点に対する測定所要時間は約１
５時間であ−たが、本実施例による保磁力測定では、同
数の測定点について、約６分４０秒で測定が完了した。For example, the coercive force of a medium 19 having a recording area from a radius of 50 mm to a radius of 180 mm is measured at 12 measurement points separated by 3o0 for each measurement radius, for a total of 166 points.
As a result of measuring 0 measurement points, the measurement time required for all measurement points was approximately 1 when using the conventional configuration.
However, in the coercive force measurement according to this example, the measurement was completed in about 6 minutes and 40 seconds for the same number of measurement points.

以上のように本実施例によれば、媒体１９の移動中に保
磁力測定ができ、従来の百分の一以下という極めて短時
間に媒体１９の保磁力分布を測定することができる。As described above, according to this embodiment, the coercive force can be measured while the medium 19 is moving, and the coercive force distribution of the medium 19 can be measured in an extremely short time of one hundredth or less compared to the conventional method.

なお、本実施例の構成による保磁力測定装置は光磁気デ
ィスクの磁性媒体製造装置と組み合わせることにより、
磁性媒体製造時の保磁力モニタとして利用することがで
きる。また、本実施例の構成による保磁力測定装置は光
磁気ディスクの記録再生機と組み合わせることにより、
保磁力の大小に応じて記録又は消去条件を制御すること
ができる。Furthermore, by combining the coercive force measuring device with the configuration of this embodiment with a magnetic medium manufacturing device for magneto-optical disks,
It can be used as a coercive force monitor when manufacturing magnetic media. Furthermore, by combining the coercive force measuring device with the configuration of this embodiment with a magneto-optical disk recording/reproducing machine,
Recording or erasing conditions can be controlled depending on the magnitude of coercive force.

発明の効果 本発明は、光磁気記録媒体の移動中に保磁力測定ができ
るとともに、保磁力測定時間を大幅に短縮できる保磁力
測定装置全実現でき、その効果は犬なるものがある。Effects of the Invention The present invention can realize a complete coercive force measuring device that can measure coercive force while the magneto-optical recording medium is in motion and can significantly shorten the time for measuring coercive force, and has excellent effects.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は従来の保磁力測定装置の構成図、第２図は本発
明の一実施例における保磁力測定装置の概略構成図、第
３図は同磁界引加素子が作る磁界分布図、第４図は同保
磁力測定装置の構成図である０ １　・光源、１４・　シリンドリカルレンズ、１５．１
６・　磁界印加素子、１７．２３　・　受光器、１９　
・・光磁気記録媒体、２１　回転機。 代理人の氏名　弁理士　中　尾　敏　男　ほか１名第１
図 第２図 第３図 第４図 ／／７Fig. 1 is a block diagram of a conventional coercive force measuring device, Fig. 2 is a schematic block diagram of a coercive force measuring device according to an embodiment of the present invention, and Fig. 3 is a magnetic field distribution diagram generated by the same magnetic field attracting element. Figure 4 is a configuration diagram of the coercive force measuring device. 0 1 - Light source, 14 - Cylindrical lens, 15.1
6. Magnetic field applying element, 17.23. Light receiver, 19
...Magneto-optical recording medium, 21 rotating machine. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4 //7

Claims (3)

【特許請求の範囲】[Claims] （１）　レーザ等の光源からの光を集光するシリンドリ
カルレンズと、前記シリンドリカルレンズからの光を透
過又は反射してなる光磁気記録媒体と、前記光が透過又
は反射される前記光磁気記録媒体部分に磁界を印加しか
つ前記光磁気記録媒体を挾むように設けられた複数個の
磁界印加素子と、前記光磁気記録媒体の透過又は反射光
を受光する複数個の受光素子を有する受光器とを備えた
ことを特徴とする保磁力測定装置。(1) A cylindrical lens that focuses light from a light source such as a laser, a magneto-optical recording medium that transmits or reflects the light from the cylindrical lens, and a magneto-optical recording medium that transmits or reflects the light. a plurality of magnetic field applying elements that apply a magnetic field to a portion and are provided to sandwich the magneto-optical recording medium; and a light receiver that has a plurality of light-receiving elements that receive transmitted or reflected light from the magneto-optical recording medium. A coercive force measuring device characterized by: （２）２個の磁界印加素子が同磁極を向は合い、かつ偏
心配置したことを特徴とする特許請求の範囲第１項記載
の保磁力測定装置。(2) The coercive force measuring device according to claim 1, wherein the two magnetic field applying elements have the same magnetic poles facing each other and are arranged eccentrically. （３）光の通過を防げない部分を有する磁界印加素子を
備えたこと全特徴とする特許請求の範囲第１項記載の保
磁力測定装置。(3) The coercive force measuring device according to claim 1, further comprising a magnetic field applying element having a portion that cannot prevent light from passing through.
JP4332484A 1984-03-06 1984-03-06 Coercive force measuring device Expired - Lifetime JPH0646215B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP4332484A JPH0646215B2 (en) 1984-03-06 1984-03-06 Coercive force measuring device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP4332484A JPH0646215B2 (en) 1984-03-06 1984-03-06 Coercive force measuring device

Publications (2)

Publication Number Publication Date
JPS60186768A true JPS60186768A (en) 1985-09-24
JPH0646215B2 JPH0646215B2 (en) 1994-06-15

Family

ID=12660631

Family Applications (1)

Application Number Title Priority Date Filing Date
JP4332484A Expired - Lifetime JPH0646215B2 (en) 1984-03-06 1984-03-06 Coercive force measuring device

Country Status (1)

Country Link
JP (1) JPH0646215B2 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63302384A (en) * 1987-06-03 1988-12-09 Hitachi Ltd Magnetic defect inspecting apparatus

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63302384A (en) * 1987-06-03 1988-12-09 Hitachi Ltd Magnetic defect inspecting apparatus

Also Published As

Publication number Publication date
JPH0646215B2 (en) 1994-06-15

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