JPH0668434A - Magnetic head noise detecting system - Google Patents

Magnetic head noise detecting system

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Publication number
JPH0668434A
JPH0668434A JP22113992A JP22113992A JPH0668434A JP H0668434 A JPH0668434 A JP H0668434A JP 22113992 A JP22113992 A JP 22113992A JP 22113992 A JP22113992 A JP 22113992A JP H0668434 A JPH0668434 A JP H0668434A
Authority
JP
Japan
Prior art keywords
magnetic head
circuit
head
magnetic
noise
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
JP22113992A
Other languages
Japanese (ja)
Other versions
JP2814850B2 (en
Inventor
Ichiro Ochi
一郎 越智
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.)
NEC Corp
Original Assignee
NEC Corp
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 NEC Corp filed Critical NEC Corp
Priority to JP22113992A priority Critical patent/JP2814850B2/en
Publication of JPH0668434A publication Critical patent/JPH0668434A/en
Application granted granted Critical
Publication of JP2814850B2 publication Critical patent/JP2814850B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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  • Recording Or Reproducing By Magnetic Means (AREA)

Abstract

PURPOSE:To select a magnetic head set in an unstably magnetized state and to improve yielding by performing the read/write of a signal by using a magnetic head heated between 40-80 deg.C, transiting the head from the unstably magnetized state to a stably magnetized state, and detecting a noise generated at that time. CONSTITUTION:The magnetic head 1 is connected to a write circuit 3 and a read circuit 4, and the head 1 is heated in temperature higher than constant temperature by irradiating the head with a laser beam from an HeNe laser beam generator 2. A write operation is performed on a magnetic disk medium in such state by the circuit 3, and after that, readout is performed. When the write operation is performed, the reversal of magnetization of a magnetic material which comprises the head 1 occurs according to the polarity of a write current, however, such reversal state depends on frequency, therefore, the frequency is set at the same one used in the head. Also, an output signal from the circuit 4 is inputted to a pulse detection circuit 5, and a pulse exceeding a threshold value set in advance i.e., the noise is detected, and the number of pulses is counted by a pulse counter circuit 6, thereby, the head in which an excessive noise is generated can be identified.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は磁気ヘッドのノイズ検出
方式に関し、特に薄膜磁気ヘッドの選別に用いるノイズ
検出方式に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head noise detection method, and more particularly to a noise detection method used for selecting a thin film magnetic head.

【０００２】[0002]

【従来の技術】従来、磁気ヘッドの特性試験において、
出力信号を試験する場合には、例えば、オッシロスコー
プを用いて信号波形を観測している。2. Description of the Related Art Conventionally, in a characteristic test of a magnetic head,
When testing the output signal, for example, the signal waveform is observed using an oscilloscope.

【０００３】[0003]

【発明が解決しようとする課題】しかしながら、特に漠
膜磁気ヘッドでは、磁気ディスク媒体に書き込まれた信
号を読み出す際に、瞬間的にノイズ（図２を参照）を発
生することがある。このようなノイズの発生は、薄膜磁
気ヘッドの磁気回路を構成する軟磁性薄膜、例えば、Ｎ
ｉＦｅ膜の磁区の不安定性に起因すると考えられてい
る。また、このノイズの再現性は悪く、かつ過渡的なも
のであり、しかも、ノイズの発生する確率は、数万回の
書き込み・読み出しに１回程度と非常に小さい。However, particularly in the vague magnetic head, noise (see FIG. 2) may be momentarily generated when reading a signal written in the magnetic disk medium. The generation of such noise is caused by the soft magnetic thin film that constitutes the magnetic circuit of the thin film magnetic head, for example, N.
It is believed that this is due to the instability of magnetic domains in the iFe film. Further, the reproducibility of this noise is poor and transient, and the probability of occurrence of noise is extremely small, such as about once for every tens of thousands of writing / reading.

【０００４】従って、従来のようなオッシロスコープを
用いる方法では、ノイズを観測することができず、磁気
ヘッドの歩留りが低下するという欠点があった。Therefore, the conventional method using an oscilloscope has a drawback that noise cannot be observed and the yield of the magnetic head is reduced.

【０００５】[0005]

【課題を解決するための手段】本発明は、被測定磁気ヘ
ッドを４０〜８０℃に加熱する加熱手段と、加熱した前
記被測定磁気ヘッドにより磁気ディスク媒体に信号を書
き込むための書込み回路と、前記被測定磁気ヘッドが前
記磁気ディスク媒体から読み出した信号を再生する読出
し回路と、この再生信号から所定の閾値を超えるノイズ
を検出するパルス検出回路と、検出したノイズを個数を
計測するパルスカウント回路とを備えている。また、前
記加熱手段が、前記比測定磁気ヘッドにレーザ光を照射
するＨｅＮｅレーザ光発生機であってもよい。According to the present invention, there is provided heating means for heating a magnetic head to be measured to 40 to 80 ° C., and a writing circuit for writing a signal on a magnetic disk medium by the heated magnetic head to be measured. A read circuit for reproducing a signal read from the magnetic disk medium by the magnetic head to be measured, a pulse detection circuit for detecting noise exceeding a predetermined threshold value from the reproduced signal, and a pulse counting circuit for measuring the number of detected noises. It has and. The heating means may be a HeNe laser light generator that irradiates the ratio measuring magnetic head with laser light.

【０００６】[0006]

【実施例】次に、本発明について図面を参照して説明す
る。DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

【０００７】図１は本発明の一実施例を示すブロック図
である。磁気ヘッド１は、書込回路３および読出し回路
４に接続されている。そして、磁気ヘッド１は、ＨｅＮ
ｅレーザー光発生機２により発生させられたＨｅＮｅレ
ーザ光で照射され、常温より高い温度に加熱される。FIG. 1 is a block diagram showing an embodiment of the present invention. The magnetic head 1 is connected to the writing circuit 3 and the reading circuit 4. The magnetic head 1 is HeN
It is irradiated with HeNe laser light generated by the e laser light generator 2 and heated to a temperature higher than room temperature.

【０００８】この状態において、書込回路３により磁気
ディスク媒体に書込操作を行ない、その後に読み出しを
行なう。書込み操作のとき、磁気ヘッド１を形成する磁
性体は、書込み回路３から送出される書込み電流の極性
に従って磁化反転するが、その磁化反転状態は周波数に
よって異なるため、実際にその磁気ヘッドが使用される
磁気ディスク装置の使用周波数と同じ周波数で駆動する
のが望ましい。In this state, the write circuit 3 performs a write operation on the magnetic disk medium, and then a read operation is performed. At the time of a write operation, the magnetic material forming the magnetic head 1 undergoes magnetization reversal according to the polarity of the write current sent from the writing circuit 3, but since the magnetization reversal state differs depending on the frequency, the magnetic head is actually used. It is desirable to drive at the same frequency as the operating frequency of the magnetic disk drive.

【０００９】読出し回路４からの出力信号は、パルス検
出回路５に入力される。パルス検出回路５では予め設定
された閾値以上のパルス（ノイズ）を検出する。そし
て、パルスカウント回路６によってパルスの個数を計測
する。これによって、図２に示すような、ノイズＶｅを
発生する磁気ヘッドを選別することができる。The output signal from the read circuit 4 is input to the pulse detection circuit 5. The pulse detection circuit 5 detects pulses (noise) equal to or higher than a preset threshold value. Then, the pulse count circuit 6 counts the number of pulses. This makes it possible to select the magnetic head that generates the noise Ve as shown in FIG.

【００１０】なお、このノイズと発生温度との関係を実
検等により評価してみると、４０℃以上で発生ノイズの
カウント数が増加することが判明した。また、磁気ヘッ
ドの組立に用いる接着剤は、８０℃を超えると変質する
恐れがある。従って、ノイズ測定は、４０〜８０℃で行
うのが、より精度よく検出できることになる。When the relationship between the noise and the generated temperature was evaluated by actual inspection, it was found that the count number of the generated noise increased at 40 ° C. or higher. Further, the adhesive used for assembling the magnetic head may be deteriorated when the temperature exceeds 80 ° C. Therefore, noise measurement at 40 to 80 ° C. enables more accurate detection.

【００１１】次に、このノイズ方式の原理について説明
する。Next, the principle of this noise method will be described.

【００１２】まず、書込回路３を駆動して磁気ヘッド１
に書込操作を行う。そうすると、書込操作が終った後
に、磁気ヘッド１を形成する磁性体はある磁化状態にな
る。この磁化状態が不安定、すなわち、磁区が不安定な
状態にあるとすると、磁性体はレーザ光の照射による温
度上昇により、強制的に安定な状態に遷移させられるた
め、磁気ヘッド１は、図３に示すようなノイズＶN を発
生する。ところが、磁性体の磁区が安定ならば、加熱し
ても磁区状態は変化しないためにノイズの発生はない。First, the write circuit 3 is driven to drive the magnetic head 1.
Write operation to. Then, after the write operation is completed, the magnetic material forming the magnetic head 1 is in a certain magnetized state. If this magnetization state is unstable, that is, if the magnetic domains are in an unstable state, the magnetic body is forced to transition to a stable state due to the temperature rise due to the irradiation of the laser light, so that the magnetic head 1 Noise VN as shown in 3 is generated. However, if the magnetic domain of the magnetic material is stable, no noise is generated because the magnetic domain state does not change even when heated.

【００１３】従って、図３に示すように、ノイズＶN を
予め適当な閾値（＋）Ｖｓ＋または（−）Ｖｓ−に設定
し、パルス検出回路５を用いて検出すれば、不安定な磁
化状態を持つ磁気ヘッド、すなわち、図２に示すような
ノイズを発生するヘッドを選別できる。Therefore, as shown in FIG. 3, if the noise VN is set to an appropriate threshold value (+) Vs + or (-) Vs- in advance and the noise is detected by the pulse detection circuit 5, an unstable magnetization state is generated. It is possible to sort out the magnetic heads it has, that is, the heads that generate noise as shown in FIG.

【００１４】[0014]

【発明の効果】以上説明したように本発明は、４０〜８
０℃に加熱した磁気ヘッドを用いて、信号の書き込み・
読み出しを行うことにより、磁気ヘッドの不安定な磁化
状態を安定な磁化状態に遷移させ、そのときに生じるノ
イズを検出することにより、不安定な磁化状態を持つ磁
気ヘッドを選別することができるため、歩留りをを向上
できるという効果を有している。As described above, the present invention is 40 to 8
Write a signal using a magnetic head heated to 0 ° C
By reading out, the unstable magnetization state of the magnetic head transits to a stable magnetization state, and by detecting the noise generated at that time, the magnetic head having the unstable magnetization state can be selected. It has the effect of improving the yield.

【図面の簡単な説明】[Brief description of drawings]

【図１】本発明の一実施例を示すブロック図である。FIG. 1 is a block diagram showing an embodiment of the present invention.

【図２】磁気ヘッドから発生するノイズ波形の一例を示
す図である。FIG. 2 is a diagram showing an example of a noise waveform generated from a magnetic head.

【図３】磁気ヘッドを構成する磁性体が安定状態から不
安定状態に遷移する際に発生するノイズ波形の一例を示
す図である。FIG. 3 is a diagram showing an example of a noise waveform generated when a magnetic material forming a magnetic head transits from a stable state to an unstable state.

【符号の説明】 １ 磁気ヘッド ２ ＨｅＮｅレーザ光発生機 ３ 書込み回路 ４ 読出し回路 ５ パルス検出回路 ６ パルスカウント回路[Explanation of Codes] 1 magnetic head 2 HeNe laser light generator 3 writing circuit 4 reading circuit 5 pulse detecting circuit 6 pulse counting circuit

Claims (2)

【特許請求の範囲】[Claims] 【請求項１】 被測定磁気ヘッドを４０〜８０℃に加熱
する加熱手段と、加熱した前記被測定磁気ヘッドにより
磁気ディスク媒体に信号を書き込むための書込み回路
と、前記被測定磁気ヘッドが前記磁気ディスク媒体から
読み出した信号を再生する読出し回路と、この再生信号
から所定の閾値を超えるノイズを検出するパルス検出回
路と、検出したノイズの個数を計測するパルスカウント
回路とを備えることを特徴とする磁気ヘッドノイズ検出
方式。1. A heating means for heating a magnetic head to be measured to 40 to 80 ° C., a write circuit for writing a signal to a magnetic disk medium by the heated magnetic head to be measured, and the magnetic head to be measured has a magnetic field. It is characterized by comprising a read circuit for reproducing a signal read from the disk medium, a pulse detection circuit for detecting noise exceeding a predetermined threshold value from the reproduced signal, and a pulse count circuit for measuring the number of detected noises. Magnetic head noise detection method. 【請求項２】 前記加熱手段が、前記被測定磁気ヘッド
にレーザ光を照射するＨｅＮｅレーザー光発生機である
ことを特徴とする請求項１記載の磁気ヘッドノイズ検出
方式。2. The magnetic head noise detection method according to claim 1, wherein the heating means is a HeNe laser light generator that irradiates the measured magnetic head with laser light.
JP22113992A 1992-08-20 1992-08-20 Magnetic head noise detection method Expired - Fee Related JP2814850B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP22113992A JP2814850B2 (en) 1992-08-20 1992-08-20 Magnetic head noise detection method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP22113992A JP2814850B2 (en) 1992-08-20 1992-08-20 Magnetic head noise detection method

Publications (2)

Publication Number Publication Date
JPH0668434A true JPH0668434A (en) 1994-03-11
JP2814850B2 JP2814850B2 (en) 1998-10-27

Family

ID=16762077

Family Applications (1)

Application Number Title Priority Date Filing Date
JP22113992A Expired - Fee Related JP2814850B2 (en) 1992-08-20 1992-08-20 Magnetic head noise detection method

Country Status (1)

Country Link
JP (1) JP2814850B2 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08182714A (en) * 1994-12-28 1996-07-16 Mutsumi Tekunika:Kk Coffin for burying small animal

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08182714A (en) * 1994-12-28 1996-07-16 Mutsumi Tekunika:Kk Coffin for burying small animal

Also Published As

Publication number Publication date
JP2814850B2 (en) 1998-10-27

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