JPS626403A - Head amplifier device - Google Patents
Head amplifier deviceInfo
- Publication number
- JPS626403A JPS626403A JP14353085A JP14353085A JPS626403A JP S626403 A JPS626403 A JP S626403A JP 14353085 A JP14353085 A JP 14353085A JP 14353085 A JP14353085 A JP 14353085A JP S626403 A JPS626403 A JP S626403A
- Authority
- JP
- Japan
- Prior art keywords
- head
- circuit
- differential amplifier
- amplifier circuit
- resistance
- 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
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/02—Recording, reproducing, or erasing methods; Read, write or erase circuits therefor
Landscapes
- Magnetic Heads (AREA)
- Recording Or Reproducing By Magnetic Means (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
この発明は、２端子構成である磁気抵抗効果型ヘッドを
、差動構成でアンプ回路に直結したヘッドアンプ装置に
関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a head amplifier device in which a two-terminal magnetoresistive head is directly connected to an amplifier circuit in a differential configuration.
微少磁気の検出に用いられる磁気抵抗効果型ヘッドは、
コアに線材を巻き付ける従来の磁気ヘッド等に比較して
コンパクトに構成できるため、ディジタルオーディオテ
ープレコーダ（略称ＤＡＴ ）等への応用が実用段階に
入っている。ＤＡＴは。The magnetoresistive head used to detect minute magnetism is
Since it can be constructed more compactly than conventional magnetic heads, etc. in which a wire is wound around a core, its application to digital audio tape recorders (abbreviated as DAT) has entered the practical stage. DAT is.
磁気テープ上のかなりの数の平行トラックに記録された
信号を、トラックごとに対応する磁気抵抗効果屋ヘッド
により検出し０個々にアンプ回路等で増幅する構成をと
る。The signal recorded on a considerable number of parallel tracks on a magnetic tape is detected by a magnetoresistive head corresponding to each track and amplified individually by an amplifier circuit or the like.
第２図に示すこの種のヘッドアンプ装置１は。This type of head amplifier device 1 is shown in FIG.
複数の２端子構成の磁気抵抗効果型ヘッド２を。A plurality of magnetoresistive heads 2 having a two-terminal configuration.
それぞれ一方の端子を接地するとともに、他方の端子に
定電流源回路３を接続し、磁気抵抗効果型ヘッド２の端
子電圧を、結合コンデンサＣを介して、アンプ回路４に
供給する構成とされている。One terminal of each is grounded, a constant current source circuit 3 is connected to the other terminal, and the terminal voltage of the magnetoresistive head 2 is supplied to the amplifier circuit 4 via the coupling capacitor C. There is.
磁気テープ５上の磁気抵抗効果型ヘッド２に対応するト
ラックに記録された信号は、磁気抵抗効果型ヘッド２の
抵抗変化として読み取られ、定電流源回路３からの一定
電流に応じて生ずる電圧降下が、アンプ回路４によって
増幅されて出力される。The signal recorded on the track corresponding to the magnetoresistive head 2 on the magnetic tape 5 is read as a resistance change of the magnetoresistive head 2, and a voltage drop that occurs in response to a constant current from the constant current source circuit 3. is amplified by the amplifier circuit 4 and output.
上記従来のヘッドアンプ装置１は、磁気抵抗効果型ヘッ
ド２を流れる直流成分にもとづく直流電圧が、アンプ回
路４に入力されないようにする上で、ｆＢ気低抵抗効果
型ヘッド２アンプ回路４の間に、かならず結合コンデン
サＣを必要とする。このため、ヘッドアンプ装置ｌｌを
集積化する上で支障を来しやすく、特にＤＡＴのように
２０個程腿の磁気抵抗効果型ヘッド２を並列配置する場
合には。The above-mentioned conventional head amplifier device 1 is designed to prevent the direct current voltage based on the direct current component flowing through the magnetoresistive head 2 from being input to the amplifier circuit 4. Therefore, a coupling capacitor C is always required. This tends to cause problems when integrating the head amplifier device 11, especially when about 20 magnetoresistive heads 2 such as a DAT are arranged in parallel.
特に厄介な問題であった。This was a particularly troublesome problem.
また、上記従来のヘッドアンプ装置１は、外来ノイズに
対して弱（、ＳＮ比の劣化を招きやすい等の問題点があ
った。Further, the conventional head amplifier device 1 has problems such as being weak against external noise (and easily causing deterioration of the S/N ratio).
この＠明は、上記問題点を解決したものであり。 This @Ming solves the above problem.
鎖交する磁束に応じて抵抗値が変化する磁気抵抗効果壁
ヘッドと、この磁気抵抗効果型ヘッドの両端に接続した
正負一対の定電流源回路と、＃記磁気抵抗効果盟ヘッド
の両端の電圧を差動入力とする差動アンプ回路と、この
差動アンプ回路に乃還路を形成して設けられ、＠気抵抗
効果型ヘッドが磁束なしのときにもつ抵抗分に相当する
直流オフセットを除去する直流帰還回路とから構成した
ことを要旨とするものである。A magnetoresistive wall head whose resistance value changes depending on the interlinking magnetic flux, a pair of positive and negative constant current source circuits connected to both ends of this magnetoresistive head, and a voltage across the magnetoresistive head marked #. A differential amplifier circuit with a differential input of The gist of this is that it is constructed from a DC feedback circuit.
この発明は１両端に正負一対の定電源回路が接続された
磁気抵抗効果型ヘッドの端子間電圧を。This invention detects the voltage between the terminals of a magnetoresistive head, which has a pair of positive and negative constant power supply circuits connected to both ends.
差動アンプ回路にて増幅するとともに、差動アンプ回路
に接続した直流帰還回路により、磁気抵抗効果型ヘッド
が磁束なしのときにもつ抵抗分に相当する直流オフセッ
トを除去する。The differential amplifier circuit amplifies the signal, and a DC feedback circuit connected to the differential amplifier circuit removes a DC offset corresponding to the resistance of the magnetoresistive head when there is no magnetic flux.
以下、この発明の実施例について、第１図を参照して説
明する。第１図は、この発明のヘッドアンプ装置の一実
施例を示す回路図である。Hereinafter, embodiments of the present invention will be described with reference to FIG. FIG. 1 is a circuit diagram showing an embodiment of the head amplifier device of the present invention.
第１図中、ヘッドアンプ装置１１は、２端子構成の磁気
抵抗効果型ヘッド２の両端に、正負一対の定電流源回路
１２ 、１３を接続するとともに、磁気抵抗効果部ヘッ
ド２両端の端子電圧を差動アンプ回路１４の差動入力と
し、差動アンプ回路１４の差動出力をオフセット除去用
の直流帰還回路１５を介して入力側に帰還させる構成と
しである。In FIG. 1, a head amplifier device 11 has a pair of positive and negative constant current source circuits 12 and 13 connected to both ends of a magnetoresistive head 2 having a two-terminal configuration, and a terminal voltage across both ends of the magnetoresistive head 2. is used as a differential input of the differential amplifier circuit 14, and the differential output of the differential amplifier circuit 14 is fed back to the input side via a DC feedback circuit 15 for offset removal.
定電流源回路１２ 、１３は、それぞれ電流の送り出し
と引き込みのためのものであり、ともにベース・エミッ
タ間に接続した２個のダイオードＤａ 、 Ｄｂの順方
向電圧降下分に相当するベースバイアスのかかったトラ
ンジスタＱｘｔ ＊ Ｑｔｓ により、一定電流の供
給を行う、すなわち、トランジスタＱ、のコレクタ電流
と、トランジスタＱ１３のエミッタ電流は、ともに定電
流であり、コレクタ電流とエミッタ電流は、はぼ相等し
い、なお、磁気抵抗効果盤ヘッド２の両端は１分流抵抗
凡、 、 Ｒ＋、を介して接地しである。The constant current source circuits 12 and 13 are for sending and drawing current, respectively, and both have a base bias equivalent to the forward voltage drop of two diodes Da and Db connected between the base and emitter. A constant current is supplied by the transistor Qxt * Qts , that is, the collector current of the transistor Q and the emitter current of the transistor Q13 are both constant currents, and the collector current and emitter current are approximately equal in phase. , both ends of the magnetoresistive head 2 are grounded through one shunt resistor, , R+.
差動アンプ回路１４は、（ａ気抵抗効果型ヘッド２の一
方の端子が入力抵抗島を介して分圧抵抗Ｒ４利きの非反
転入力端子に接続され、他方の端子が入力抵抗Ｒ，を介
して分圧抵抗Ｒ６付きの反転入力端子に接続されている
０反転入力端子と出力端子の間には、帰還抵抗Ｒ，が接
続してあり、この帰還抵抗Ｒ丁に並列の直流帰還回路１
５により多重廓還がかけられる。The differential amplifier circuit 14 is configured such that (one terminal of the a-air resistance effect type head 2 is connected to a non-inverting input terminal of a voltage dividing resistor R4 via an input resistor island, and the other terminal is connected via an input resistor R, A feedback resistor R is connected between the 0 inverting input terminal connected to the inverting input terminal with the voltage dividing resistor R6 and the output terminal, and a DC feedback circuit 1 is connected in parallel to this feedback resistor R.
5, multiple circulation is applied.
直流帰還回路１５は、上記差動アンプ回路１４の出力が
非反転入力端子に供給される差動アンプ回路［６を有し
、差動アンプ回路１６の反転入力端子に接続した抵抗も
と帰還抵抗Ｒ，の抵抗比により決る非反転増幅が行われ
る。差動アンプ回路１６の出力端子は、抵抗ＲＩＯを介
して、前記分圧抵抗Ｒ６に接続してあり、また抵抗Ｒ１
ｏと分圧抵抗Ｒ＋６の中点は、コンデンサＣ，を介して
接地しである。The DC feedback circuit 15 includes a differential amplifier circuit [6] to which the output of the differential amplifier circuit 14 is supplied to a non-inverting input terminal, and includes a resistor and a feedback resistor connected to the inverting input terminal of the differential amplifier circuit 16. Non-inverting amplification is performed depending on the resistance ratio of R. The output terminal of the differential amplifier circuit 16 is connected to the voltage dividing resistor R6 via a resistor RIO, and is connected to the resistor R1.
The midpoint between o and voltage dividing resistor R+6 is grounded via capacitor C.
ここで、磁束変化がないときの磁気抵抗効果型ヘッド２
自体が示す抵抗値を鳥、そのときに定電流源回路１２
、１３間に流れる１流をＩＯとすると。Here, the magnetoresistive head 2 when there is no change in magnetic flux.
When the resistance value shown by itself is determined by the constant current source circuit 12,
Let IO be the first flow flowing between , 13.
磁気抵抗効果型ヘッド２の端子間電圧ＶＡＢは。The voltage VAB between the terminals of the magnetoresistive head 2 is:
■。Ｒｏで表わされる。このとき、端子電圧Ｖ層ま。■. It is represented by Ro. At this time, the terminal voltage V layer.
Ｉｏ Ｘ ’ Ｒｏ ＝１’ｌ’ＡＢ であり、端子電圧ＶＢは。Io X Ro =1'l'AB And the terminal voltage VB is.
一工。Ｘ−Ｒ０＝−−！−Ｖ。One piece of work. X-R0=--! -V.
である、従って、差動アンプ回路１４の差動出力は。Therefore, the differential output of the differential amplifier circuit 14 is.
■。Ｘ’Ｒｏ−（−Ｉ。Ｘ−！−Ｒｏ）＝ＩｏＲ。■. X'Ro-(-I.X-!-Ro)=IoR.
となる。becomes.
これに対し、磁束変化が生じた場合の磁気抵抗効果型ヘ
ッド２の抵抗変化分をΔＲとすると、端子電圧Ｖ人、Ｖ
Ｂは、それぞれ
■。×１（Ｒ０＋Δ凡）、−１゜Ｘ±（几。＋ΔＩも）
で表わされ、差動アンプ回路１４のＭ動量力は。On the other hand, if the resistance change of the magnetoresistive head 2 when a magnetic flux change occurs is ΔR, then the terminal voltages V and V
B is each ■. ×1 (R0 + ΔB), -1°X± (几. +ΔI too)
The M dynamic force of the differential amplifier circuit 14 is expressed as follows.
Ｌ Ｘ （烏＋ Ｊ Ｒ） ＝ ＶＡＢ ＋ ＩＯΔＲ
となる。抵抗変化に応じた差動出力の変化分ｌ。几。L X (Crow + J R) = VAB + IOΔR
becomes. The change l in the differential output according to the change in resistance.几.
は、抵抗変化の極性に応じて正負に振れるため。changes to positive or negative depending on the polarity of resistance change.
差動アンプ回路１４の出力は、ＶＡＢ＝Ｉ。Ｒｏ を
中心に正負に変化することになる。The output of the differential amplifier circuit 14 is VAB=I. It will change positive and negative around Ro.
しかして、直流帰還回路１５は、差動アンプ回路１４の
出力に含まれる直流分ＶＡＢを、オフセット電圧として
消去する電圧を、差動アンプ回路１４の反転入力端子に
帰還する。この帰還量は、あらかじめ抵抗も、８９等に
より適宜値に設定しであるため、オフセット電圧は正確
に消去することができ。Thus, the DC feedback circuit 15 feeds back to the inverting input terminal of the differential amplifier circuit 14 a voltage that erases the DC component VAB included in the output of the differential amplifier circuit 14 as an offset voltage. Since this feedback amount is determined by setting the resistance in advance to an appropriate value using 89 or the like, the offset voltage can be accurately eliminated.
これにより磁気抵抗効果をヘッド２の抵抗変化分に応じ
た交流出力のみが得られる。As a result, only an AC output corresponding to the resistance change of the head 2 can be obtained due to the magnetoresistive effect.
このように、上記ヘッドアンプ装置１１は、ｉａ気抵抗
効果鳳ヘッド２の両端に正負一対の定電流源回路１２
、１３を接続し、ヘッド両端の電圧を差動入力とする差
動アンプ回路１４に直流オフセット除去用の直流帰還回
路１５を接続した構成としたから。In this way, the head amplifier device 11 has a pair of positive and negative constant current source circuits 12 at both ends of the ia resistance effect head 2.
, 13 are connected to each other, and a DC feedback circuit 15 for removing DC offset is connected to a differential amplifier circuit 14 which receives the voltage across the head as a differential input.
磁気抵抗効果盤ヘッド２の抵抗変化を電圧変化として検
出する上で、差動アンプ回路１４の同相成分除去効果に
よるノイズ対策が可能であり、さらに磁気抵抗変化分ヘ
ッド２が磁束なしのときにもつ抵抗分に相当する直流オ
フセットは、直流帰還回路１５の直流帰還量の設定値に
応じて正確に除去することができ、これにより結合コン
デンサ等を用いることなく、磁気抵抗変化分のみを検出
することができる。In detecting the resistance change of the magnetoresistive head 2 as a voltage change, it is possible to take measures against noise by the in-phase component removal effect of the differential amplifier circuit 14, and furthermore, it is possible to prevent noise by the in-phase component removal effect of the differential amplifier circuit 14. The DC offset corresponding to the resistance can be accurately removed according to the set value of the DC feedback amount of the DC feedback circuit 15, and thereby only the magnetic resistance change can be detected without using a coupling capacitor or the like. Can be done.
以上説明したように、この発明によれば、磁気抵抗効果
型ヘッドの両端に正負一対の定電流源回路を接続し、ヘ
ッド両端の電圧を差動入力とする差動アンプ回路に直流
オフセット猶去用の直流帰還回路を接続した構成とした
から、磁気抵抗効果型ヘッドの抵抗変化を電圧変化とし
て検出する上で、差動アンプ回路の同相成分除去効果に
よるノイズ対策が可能であり、さらに磁気抵抗効果型ヘ
ッドが磁束なしのときにもつ抵抗分に相当する直流オフ
セットは、直流帰還回路の直流帰還量の設定値に応じて
正確に除去することができ、これにより結合コンデンサ
等を用いることなく、磁気抵抗変化分のみを検出するこ
とができる等の優れた効果を奏する。As explained above, according to the present invention, a pair of positive and negative constant current source circuits are connected to both ends of a magnetoresistive head, and a DC offset is applied to a differential amplifier circuit that receives the voltage across the head as a differential input. Since the structure is connected to a direct current feedback circuit for magnetoresistive heads, it is possible to detect resistance changes of the magnetoresistive head as voltage changes, and noise countermeasures are possible by the common mode component removal effect of the differential amplifier circuit. The DC offset corresponding to the resistance that the effect head has when there is no magnetic flux can be accurately removed according to the DC feedback amount setting of the DC feedback circuit. This provides excellent effects such as being able to detect only the change in magnetic resistance.
第１図は、この発明のヘッドアンプ装置の一実施例を示
す回路図、第２図は、従来のヘッドアンプ装置の一例を
示す回路図である。
２・・・磁気抵抗効果型ヘッド、１２ 、１３・・・定
電流源回路、１４・・・差動アンプ回路、１５・・・直
流帰還回路。FIG. 1 is a circuit diagram showing an embodiment of a head amplifier device of the present invention, and FIG. 2 is a circuit diagram showing an example of a conventional head amplifier device. 2... Magnetoresistive head, 12, 13... Constant current source circuit, 14... Differential amplifier circuit, 15... DC feedback circuit.
Claims (1)
ヘッドと、この磁気抵抗効果型ヘッドの両端に接続した
正負一対の定電流源回路と、前記磁気抵抗効果型ヘッド
の両端の電圧を差動入力とする差動アンプ回路と、この
差動アンプ回路に帰還路を形成して設けられ、磁気抵抗
効果型ヘッドが磁束なしのときにもつ抵抗分に相当する
直流オフセットを除去する直流帰還回路とからなるヘッ
ドアンプ装置。A magnetoresistive head whose resistance value changes according to the interlinking magnetic flux, a pair of positive and negative constant current source circuits connected to both ends of the magnetoresistive head, and a voltage across the magnetoresistive head. A differential amplifier circuit for differential input, and a DC feedback circuit that is provided by forming a feedback path in the differential amplifier circuit to remove the DC offset corresponding to the resistance of the magnetoresistive head when there is no magnetic flux. A head amplifier device consisting of a circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14353085A JPS626403A (en) | 1985-06-29 | 1985-06-29 | Head amplifier device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14353085A JPS626403A (en) | 1985-06-29 | 1985-06-29 | Head amplifier device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS626403A true JPS626403A (en) | 1987-01-13 |
Family
ID=15340881
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14353085A Pending JPS626403A (en) | 1985-06-29 | 1985-06-29 | Head amplifier device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS626403A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0497581A2 (en) * | 1991-01-31 | 1992-08-05 | International Business Machines Corporation | Low noise voltage-biasing amplifier circuit for magnetoresistive element |
| US6262628B1 (en) | 1999-06-23 | 2001-07-17 | Mitsubishi Denki Kabushiki Kaisha | Differential amplifier circuit |
| US9605726B2 (en) | 2015-02-03 | 2017-03-28 | Tenneco Automotive Operating Company Inc. | Secondary dampening assembly for shock absorber |
| US9822837B2 (en) | 2015-02-06 | 2017-11-21 | Tenneco Automotive Operating Company Inc. | Secondary dampening assembly for shock absorber |
-
1985
- 1985-06-29 JP JP14353085A patent/JPS626403A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0497581A2 (en) * | 1991-01-31 | 1992-08-05 | International Business Machines Corporation | Low noise voltage-biasing amplifier circuit for magnetoresistive element |
| EP0497581A3 (en) * | 1991-01-31 | 1993-01-13 | International Business Machines Corporation | Low noise voltage-biasing amplifier circuit for magnetoresistive element |
| US6262628B1 (en) | 1999-06-23 | 2001-07-17 | Mitsubishi Denki Kabushiki Kaisha | Differential amplifier circuit |
| US9605726B2 (en) | 2015-02-03 | 2017-03-28 | Tenneco Automotive Operating Company Inc. | Secondary dampening assembly for shock absorber |
| US9822837B2 (en) | 2015-02-06 | 2017-11-21 | Tenneco Automotive Operating Company Inc. | Secondary dampening assembly for shock absorber |
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