JPH01109212A - Absolute magnetic encoder - Google Patents

Absolute magnetic encoder

Info

Publication number
JPH01109212A
JPH01109212A JP26398087A JP26398087A JPH01109212A JP H01109212 A JPH01109212 A JP H01109212A JP 26398087 A JP26398087 A JP 26398087A JP 26398087 A JP26398087 A JP 26398087A JP H01109212 A JPH01109212 A JP H01109212A
Authority
JP
Japan
Prior art keywords
magnetization
arrays
magnetization pattern
magnetic
stripe
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
Application number
JP26398087A
Other languages
Japanese (ja)
Inventor
Mitsuaki Ikeda
満昭 池田
Hisayuki Kako
久幸 加来
Shinji Yamashita
山下 慎次
Hiroyuki Ono
博之 小野
Kenji Hara
賢治 原
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.)
Yaskawa Electric Corp
Original Assignee
Yaskawa Electric Manufacturing 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 Yaskawa Electric Manufacturing Co Ltd filed Critical Yaskawa Electric Manufacturing Co Ltd
Priority to JP26398087A priority Critical patent/JPH01109212A/en
Priority to US07/159,745 priority patent/US4851771A/en
Publication of JPH01109212A publication Critical patent/JPH01109212A/en
Pending legal-status Critical Current

Links

Abstract

PURPOSE:To obtain an encoder from which a change in output can be largely taken and which has high resolving power by reversing the magnetization directions of the magnetized parts within one magnetization pattern array from each other with the nonmagnetized parts in-between. CONSTITUTION:This encoder consists of a magnetic recording medium 3 formed on the side face of a drum 2, a detecting head consisting of magneto-resistance effect elements 5 formed on a substrate 4 and conductor terminals 6 and a driving detecting circuit 8. Five pieces of the magnetization pattern arrays n1-n5 are written on the medium 3 as shown by arrows in the figure and the magnetic fields H leaking therefrom act on the corresponding elements 5. The transverse direction of the stripes of the elements 5 is parallel with the direction of the arrays n1-n5 and the magnetic fields of the arrays n1-n5 are impressed in the transverse direction of the stripes; in addition, the magnetization directions of the magnetized parts of the respective arrays in the arrays n3-n5 are reversed from each other with the nonmagnetized parts in-between. The magnetic field applied on the center of the nonmagnetized part within one magnetization pattern array is, therefore, zero and the output is hardly lowered even if the pitch P is reduced. The high resolving power is thus obtd.

Description

【発明の詳細な説明】 [産業上の利用分野] 本発明は回転体や直線運動体の絶対位置を検出するアブ
ソリュート磁気エンコーダに関する。
DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an absolute magnetic encoder that detects the absolute position of a rotating body or a linearly moving body.

[従来の技術] ロボットやマニピュレータに組込まれた回転または直線
運動を行なうアクチュエータの位置を瞬時に正確に測定
する検出器が要求されている。このような検出器として
は従来光電式が多用されてきた。この光電式検出器はガ
ラス円板に金属膜を蒸着しフォトリソにより作られた光
学スリットと発光ダイオードおよび受光素子としてフォ
トダイオードから構成されているため、ガラス円板が衝
箪に弱いことや、ダイオードを使っているので高温まで
使えないことや、発光、受光素子の配置上、薄肉化は不
可能という欠点があった。
[Prior Art] There is a need for a detector that can instantaneously and accurately measure the position of an actuator that is incorporated into a robot or manipulator and that performs rotational or linear motion. Conventionally, photoelectric type detectors have often been used as such detectors. This photoelectric detector consists of an optical slit made by photolithography of a metal film deposited on a glass disk, a light emitting diode, and a photodiode as a light receiving element. The disadvantage is that it cannot be used at high temperatures, and that it is impossible to reduce the thickness due to the arrangement of the light-emitting and light-receiving elements.

近年、ロボットやマニピュレータの小型化に伴ない検出
器の耐熱性向上や小型高分解能化の必要性は高まってき
た。このような要求に対し、磁化パターンの書込まれた
ドラムと磁気抵抗効果素子(以下、MR素子と略す)を
組合せた角度検出器が発明された(特開昭54−118
259)。この角度検出器は、回転軸と連動して回転す
る磁気記録媒体もしくは複数の永久磁石の配列と、この
磁気記録媒体に書込まれた磁化情報もしくは永久磁石の
配列具合を検出するMR素子と、このMR素子の抵抗変
化を検出し外部に出力する駆動検出回路よりなる。そし
て回転角の絶対値が読めるようにその磁化パターンの列
もしくは永久磁石の配列、すなわち情報トラックを多数
設け、その各々にMR素子を設けている。このエンコー
ダにおけるMR素素子ストライ炎長方向は磁界の方向と
直角に、またストライプ幅方向は回転体円周方向と平行
になっている。このような構成において磁気記録媒体か
らの磁界■。つがMR素子に印加されたときMR素子に
入る磁界Reftは反磁界をHdとするとHatr=H
e、l −Hd となる(特開昭57−197885)。
In recent years, with the miniaturization of robots and manipulators, the need for improved heat resistance and smaller size and higher resolution detectors has increased. In response to these demands, an angle detector was invented that combined a drum with a magnetization pattern written thereon and a magnetoresistive element (hereinafter abbreviated as MR element) (Japanese Patent Application Laid-Open No. 118-1989).
259). This angle detector includes a magnetic recording medium that rotates in conjunction with a rotating shaft or an arrangement of a plurality of permanent magnets, and an MR element that detects magnetization information written on the magnetic recording medium or the arrangement of the permanent magnets. It consists of a drive detection circuit that detects the resistance change of this MR element and outputs it to the outside. In order to read the absolute value of the rotation angle, a large number of arrays of magnetization patterns or arrays of permanent magnets, that is, information tracks, are provided, and an MR element is provided in each of them. In this encoder, the length direction of the MR element stripe flame is perpendicular to the direction of the magnetic field, and the width direction of the stripe is parallel to the circumferential direction of the rotating body. In such a configuration, the magnetic field from the magnetic recording medium ■. is applied to the MR element, the magnetic field Reft entering the MR element is Hatr=H, where Hd is the demagnetizing field.
e, l -Hd (Japanese Unexamined Patent Publication No. 197885-1985).

ここで、MR素子のパターン幅をW%膜厚をt%MR素
子の飽和磁界を1.とすると、反磁界11dは L=  4π1.・− なので、磁界Haffは 11゜tt−11,@ −4π13・−となる。つまり
、パターン幅Wが小さくなると反磁界H,が大きくなり
、磁界Hetfが小さくなるのでMR素子の出力低下が
あこる。普通、パターン幅Wの2倍が位置読取単位と考
えてよいので、このような構造ではMRパターン幅to
uが限界なので、20μが位置読取単位となる。要求さ
れている数μを達成できない。そこで本発明者らは、高
分解能化(位置読取単位を小さく)はもとより、薄くて
しかもMR素子と磁気記録媒体との距離の変動に対して
も出力変動の少ないアブソリュート磁気エンコーダを発
明した(特開昭62−39179)。
Here, the pattern width of the MR element is W%, the film thickness is t%, the saturation magnetic field of the MR element is 1. Then, the demagnetizing field 11d is L=4π1.・− Therefore, the magnetic field Haff becomes 11°tt−11, @ −4π13・−. That is, as the pattern width W becomes smaller, the demagnetizing field H becomes larger and the magnetic field Hetf becomes smaller, resulting in a decrease in the output of the MR element. Normally, twice the pattern width W can be considered as the position reading unit, so in this structure, the MR pattern width to
Since u is the limit, 20μ is the position reading unit. Unable to achieve the required number of microns. Therefore, the present inventors invented an absolute magnetic encoder that not only has high resolution (smaller position reading unit) but also is thinner and has less output fluctuations even with changes in the distance between the MR element and the magnetic recording medium (special 62-39179).

このアブソリュート磁気エンコーダは、第5図に示すよ
うに、要求される位置読取精度に応じた磁化パターンの
列を少なくとも2列有する基体(ドラム)と、この基体
より漏洩する磁界を検出するために各磁化パターン列に
配置されたストライプ状のMR素子の組合せにより前記
基体の絶対位置を読出すアブソリュート磁気エンコーダ
であって、Ml素子のストライプ長さをl、基体とMR
素子の最近接距離をg、位置読取単位をpとしたとき、
MR素子のストライプ長さ方向と前記最近接部での基体
表面接線方向とのなす角度αがイブ幅方向が前記磁化パ
ターン列方向と平行であり、ストライプ幅方向に磁化パ
ターンか、らの磁界が印加されるようにしている。
As shown in Fig. 5, this absolute magnetic encoder consists of a base (drum) that has at least two rows of magnetization patterns corresponding to the required position reading accuracy, and a drum that detects the magnetic field leaking from the base. An absolute magnetic encoder that reads out the absolute position of the substrate by a combination of striped MR elements arranged in a magnetization pattern row, wherein the stripe length of the ML element is l, and the substrate and MR
When the closest distance of the element is g and the position reading unit is p,
The angle α formed between the stripe length direction of the MR element and the substrate surface surface line direction at the nearest portion is such that the width direction is parallel to the magnetization pattern column direction, and the magnetic field from the magnetization pattern is in the stripe width direction. so that it is applied.

[発明が解決しようとする問題点] ところが、第5図に示すように1つの磁化パターン列に
おける磁化の方向が同じであるため、読取り単位が小さ
くなるにつれ着磁部aとbからの磁束が非着磁部Cに入
りこみ、非着磁部CでもMR素子にかかる磁界は着磁部
aと変わらなくなり、着磁部a、bと非着磁部Cの出力
差がなくなり高分解能化に限界があった。
[Problems to be Solved by the Invention] However, as shown in FIG. 5, since the direction of magnetization in one magnetization pattern row is the same, as the reading unit becomes smaller, the magnetic flux from the magnetized parts a and b increases. It enters the non-magnetized part C, and the magnetic field applied to the MR element in the non-magnetized part C is no different from that in the magnetized part a, and there is no output difference between the magnetized parts a and b and the non-magnetized part C, which limits the ability to achieve high resolution. was there.

[問題点を解決するための手段] 本発明の磁気エンコーダは、要求される位置読取精度に
応じた磁化パターンの列を少なくとも2列有する基体と
、この基体より漏洩する磁界を検出するために各磁化パ
ターン列に配置されたストライプ状のMR素子との組合
せにより前記基体の絶対位置を読出すアブソリュート磁
気エンコーダであって、前記MR素子のストライプ長さ
を2、基体とMR素子の最近接距離をg、位置読取単位
をpとしたとき、MR素子のストライプ長さ方向と前記
最近接部での基体表面接線方向とのなす角ストライプ幅
方向が前記磁化パターン列方向と平行であり、ストライ
プ幅方向に磁化パターンからの磁界が印加されるアブソ
リュート磁気エンコーダにおいて、1つの磁化パターン
列内において着磁部分の磁化方向が非着磁部分をはさん
で互いに逆方向にしている。
[Means for Solving the Problems] The magnetic encoder of the present invention includes a base body having at least two rows of magnetization patterns corresponding to the required position reading accuracy, and a magnetic encoder for detecting magnetic fields leaking from the base body. An absolute magnetic encoder that reads out the absolute position of the substrate by a combination with striped MR elements arranged in a magnetization pattern row, wherein the stripe length of the MR element is 2, and the closest distance between the substrate and the MR element is 2. g, when the position reading unit is p, the stripe width direction is parallel to the magnetization pattern column direction, and the stripe width direction is parallel to the magnetization pattern row direction; In an absolute magnetic encoder to which a magnetic field from a magnetized pattern is applied, the magnetization directions of magnetized portions in one magnetization pattern row are opposite to each other across non-magnetized portions.

[作 用] したがって、1つの磁化パターン列内において、非着磁
部分中央部にかかる磁界は0となり、ピッチを小さくし
ても出力が低下しにくくなり、高分解能化が可能になる
[Function] Therefore, within one magnetization pattern row, the magnetic field applied to the center of the non-magnetized portion becomes 0, and even if the pitch is made small, the output is unlikely to decrease, and high resolution becomes possible.

[実施例] 次に、本発明の実施例について図面を参照して説明する
[Example] Next, an example of the present invention will be described with reference to the drawings.

第1図は本発明のアブソリュート磁気エンコーダの一実
施例の斜視図、第2図は第1図において、磁界パターン
からのもれ磁界HがMR素子パターンに流れるセンス電
流と直交する様子を示す図、第3図はMR素子5の詳細
図、第4図は本実施例における出力電力とビット長の関
係を従来例と比較して示す図である。
FIG. 1 is a perspective view of an embodiment of the absolute magnetic encoder of the present invention, and FIG. 2 is a diagram showing how the leakage magnetic field H from the magnetic field pattern in FIG. 1 is perpendicular to the sense current flowing through the MR element pattern. , FIG. 3 is a detailed diagram of the MR element 5, and FIG. 4 is a diagram showing the relationship between output power and bit length in this embodiment in comparison with a conventional example.

本実施例は、箪1図に示すように、回転軸1に固定され
たドラム2と、その側面に形成された磁気記録媒体3と
、基板4上に形成されたMR素子5および導体端子6よ
りなる検出ヘッドと、導体端子6に接続されたリード線
7および外部への出力端子を有する駆動検出回路8とよ
りなる。磁気記録媒体3には第1図に矢印で示したよう
に5本の磁化パターン列n、〜n5が書込まれており、
これらの磁化パターンn、−%−n8から漏れる磁界が
対応するMR素子5に作用する。つまり、第2図に示す
ように、磁気記録媒体3からのもれ磁界Hは、MR素子
パターンに流れるセンス電流に直交することにより磁化
パターンnl+ n2+ n、、・・・に対しそれぞれ
位置に応じて電圧の変化を生じる。この変化を基にドラ
ム2の絶対位置を検出する。ここで、MR素子5のスト
ライプ長さをL、ドラム2とMR素子5の最近接距離を
g、位置読取単位をpとしたとき、MR素子5のストラ
イプ長さ方向と前記最近接部でのドラム2表面接線方向
とのなす角度αがtan−”<1 + g >度から9
0度の範囲にあす、ストライプ幅方向が磁化パターン列
n!〜nsの方向と平行であり、ストライプ幅方向に磁
化パターンn 、 /%I n 、からの磁界が印加さ
れる。また、1つの磁化パターン列において着磁部分の
磁化方向は非着磁部分をはさんで互いに逆方向になって
いる( n3+ ”4* ’B列参照)。
As shown in FIG. 1, this embodiment includes a drum 2 fixed to a rotating shaft 1, a magnetic recording medium 3 formed on the side surface of the drum 2, an MR element 5 formed on a substrate 4, and a conductive terminal 6. The drive detection circuit 8 has a lead wire 7 connected to a conductor terminal 6 and an output terminal to the outside. Five magnetization pattern rows n, to n5 are written on the magnetic recording medium 3 as indicated by arrows in FIG.
The magnetic field leaking from these magnetization patterns n, -%-n8 acts on the corresponding MR element 5. In other words, as shown in FIG. 2, the leakage magnetic field H from the magnetic recording medium 3 is perpendicular to the sense current flowing through the MR element pattern, and is therefore distributed depending on the position of the magnetization patterns nl+ n2+ n, . This causes a change in voltage. Based on this change, the absolute position of the drum 2 is detected. Here, when the stripe length of the MR element 5 is L, the closest distance between the drum 2 and the MR element 5 is g, and the position reading unit is p, the distance between the stripe length direction of the MR element 5 and the closest part is The angle α formed with the surface line direction of the drum 2 is 9 from tan-”<1 + g> degrees.
Tomorrow, in the 0 degree range, the stripe width direction is magnetized pattern row n! ~ns direction, and a magnetic field from the magnetization pattern n, /%In is applied in the stripe width direction. Furthermore, in one magnetization pattern row, the magnetization directions of the magnetized portions are opposite to each other across the non-magnetized portions (see n3+ "4* 'B row).

直径20mtab厚さ8mmのアルミ製ドラムの外周部
にBa−フェライト膜を厚さ100−に塗布したドラ 
4ム2を製作し、種々のビット長pをもつ磁化パターン
(磁化パターン1列の幅は300u)を着磁ヘッドで形
成し、このドラム2を第3図に示すような幅20μs、
長さ250uのパターンを4回くり返し、全長1.2m
mとしたMR素子5と組合せて出力電圧とビット長pの
関係を調べた。なお、ピットル内の着磁・非着磁部分の
比は出力時間が同じになるように0.2〜0.8の範囲
でかえた。また、センサ膜厚は600人とした。第4図
に示すように本実施例では従来例の限界である10μs
以下でも出力電圧はノイズレベルより十分大きいため、
高分解能化が可能であることが分る。
A drum made of aluminum with a diameter of 20mtab and a thickness of 8mm, with a Ba-ferrite film coated to a thickness of 100mm on the outer periphery.
A drum 2 with a width of 20 μs and a width of 20 μs as shown in FIG.
Repeat 250u long pattern 4 times, total length 1.2m
The relationship between the output voltage and the bit length p was investigated in combination with the MR element 5 having a value of m. Note that the ratio of magnetized and non-magnetized portions in the pittle was varied within the range of 0.2 to 0.8 so that the output times were the same. Further, the sensor film thickness was set to 600 people. As shown in Fig. 4, in this example, the time limit of 10 μs
Even below, the output voltage is sufficiently larger than the noise level, so
It can be seen that high resolution is possible.

[発明の効果] 以上説明したように本発明は、1つの磁化パターン列内
において着磁部分の磁化方向を非着磁部分をはさんで互
いに逆方向とすることにより、非着磁部分中央部の磁界
が0になり出力変化を大きくとれるため高分解能の磁気
エンコーダを提供できる効果がある。
[Effects of the Invention] As explained above, the present invention makes the magnetization directions of the magnetized portions opposite to each other across the non-magnetized portion within one magnetization pattern row, so that the central portion of the non-magnetized portion Since the magnetic field becomes zero and output changes can be made large, a high-resolution magnetic encoder can be provided.

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

第1図は本発明のアブソリュート磁気エンコーダの一実
施例の斜視図、第2図は第1図において、磁界パターン
からのもれ磁界HがMR素子パターンに流れるセンス電
流と直交する様子を示す図、第3図はMR素子5の詳細
図、第4図は本実施例における出力電圧とビット長pの
関係を従来例と比較して示す図、第5図は従来例を示す
図である。 1−・回転軸、     2・・・ドラム、3−磁気記
録媒体、 4・一基板、 5−M R素子、    6・−導体端子、7−・リー
ド線、   8−駆動検出回路。 第1図 シ 列 M2図     1+ ビット表e扁) 第4図 ′!A3図
FIG. 1 is a perspective view of an embodiment of the absolute magnetic encoder of the present invention, and FIG. 2 is a diagram showing how the leakage magnetic field H from the magnetic field pattern in FIG. 1 is perpendicular to the sense current flowing through the MR element pattern. , FIG. 3 is a detailed diagram of the MR element 5, FIG. 4 is a diagram showing the relationship between the output voltage and bit length p in this embodiment in comparison with a conventional example, and FIG. 5 is a diagram showing the conventional example. 1-Rotating shaft, 2-Drum, 3-Magnetic recording medium, 4-One substrate, 5-MR element, 6-Conductor terminal, 7-Lead wire, 8-Drive detection circuit. Figure 1 column M2 Figure 1+ bit table e flat) Figure 4'! A3 diagram

Claims (1)

【特許請求の範囲】 要求される位置読取精度に応じた磁化パターンの列を少
なくとも2列有する基体と、この基体より漏洩する磁界
を検出するために各磁化パターン列に配置されたストラ
イプ状の磁気抵抗効果素子との組合せにより前記基体の
絶対位置を読出すアブソリュート磁気エンコーダであっ
て、前記磁気抵抗効果素子のストライプ長さをl、基体
と磁気抵抗効果素子の最近接距離をg、位置読取単位を
pとしたとき、磁気抵抗効果素子のストライプ長さ方向
と前記最近接部での基体表面接線方向とのなす角度αが
tan^−^1([l+g]/p)度から90度の範囲
にあり、ストライプ幅方向が前記磁化パターン列方向と
平行であり、ストライプ幅方向に磁化パターンからの磁
界が印加されるアブソリュート磁気エンコーダにおいて
、 1つの磁化パターン列内において着磁部分の磁化方向が
非着磁部分をはさんで互いに逆方向であることを特徴と
するアブソリュート磁気エンコーダ。
[Scope of Claims] A base body having at least two rows of magnetization patterns corresponding to the required position reading accuracy, and a magnetic stripe arranged in each magnetization pattern row to detect magnetic fields leaking from the base body. An absolute magnetic encoder that reads the absolute position of the substrate in combination with a resistance effect element, wherein the stripe length of the magnetoresistive element is l, the closest distance between the substrate and the magnetoresistive element is g, and the position reading unit is When is p, the angle α formed between the length direction of the stripe of the magnetoresistive element and the surface line direction of the substrate surface at the nearest portion is in the range of tan^-^1 ([l+g]/p) degrees to 90 degrees. In an absolute magnetic encoder in which the stripe width direction is parallel to the magnetization pattern column direction and the magnetic field from the magnetization pattern is applied in the stripe width direction, the magnetization direction of the magnetized portion within one magnetization pattern column is non-uniform. An absolute magnetic encoder characterized by having magnetized parts in opposite directions.
JP26398087A 1987-02-24 1987-10-21 Absolute magnetic encoder Pending JPH01109212A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP26398087A JPH01109212A (en) 1987-10-21 1987-10-21 Absolute magnetic encoder
US07/159,745 US4851771A (en) 1987-02-24 1988-02-24 Magnetic encoder for detection of incremental and absolute value displacement

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP26398087A JPH01109212A (en) 1987-10-21 1987-10-21 Absolute magnetic encoder

Publications (1)

Publication Number Publication Date
JPH01109212A true JPH01109212A (en) 1989-04-26

Family

ID=17396876

Family Applications (1)

Application Number Title Priority Date Filing Date
JP26398087A Pending JPH01109212A (en) 1987-02-24 1987-10-21 Absolute magnetic encoder

Country Status (1)

Country Link
JP (1) JPH01109212A (en)

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