JPH085331A - Optical displacement measuring apparatus - Google Patents

Abstract

PURPOSE:To obtain a highly accurate displacement information stabely even if various kinds of interference fringes are generated owing to the accuracy characteristic of a scale sending mechanism by providing a plurality of light receiving cells in a photodetector. CONSTITUTION:The luminous flux, which is emitted from a light emitting element 1 and made approximately parallel with a lens 2, is cast into a diffraction grating 3A. The luminous flux is transmitted and diffracted at the grating, divided into a plurality of luminous fluxes, cast into a diffraction grating 21 on a scale 20, reflected and diffracted, divided into the + first-order diffracted light and the 0-order diffracted light and other luminous flux, and undergo phase modulation respectively at the same time. The luminous fluxes, whose optical paths are overlapped in diffractive gratings 3C1-3C4, become an interference light and cast into a photodetector 4C. The brightness signal in one period is generated from each of light receiving cells 4C1-4C4 at every time the diffraction grating 21 is moved by 1/2 pitch. The signal, which is deviated by 4/1 period in phase, is obtained in the light receiving cells 4C1-4C4 respectively. In this way, the relative displacement amount of an optical head and the scale 20 is obtained by the computation.

Description

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

【０００１】[0001]

【産業上の利用分野】本発明は光学式変位測定装置に関
し、特に２光束の干渉を利用した光学的手段によって物
体の変位情報や速度情報等（以下「変位情報」と略称す
る）を検出する変位センサ、速度センサ、加速度センサ
等の光学式変位測定装置に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical displacement measuring device, and more particularly to detecting displacement information and velocity information of an object (hereinafter abbreviated as "displacement information") by optical means utilizing interference of two light beams. The present invention relates to an optical displacement measuring device such as a displacement sensor, a speed sensor, and an acceleration sensor.

【０００２】[0002]

【従来の技術】従来より光を物体に照射し、該物体を介
した光を用いて物体の変位量や速度などの変位情報を高
精度に求める光学式変位測定装置、たとえば、光学式エ
ンコーダ、レーザードップラ速度計、レーザー干渉計な
どが、ＮＣ工作機械、ＯＡ機器、ロボット、精密製造装
置等の分野で広く利用されている。本出願人は、こうし
た光学式変位測定装置の例を、特開平5-340719号公報や
特願平4-347414号にて提案している。2. Description of the Related Art Conventionally, an optical displacement measuring device, for example, an optical encoder, which irradiates an object with light and highly accurately obtains displacement information such as the amount of displacement and speed of the object using the light transmitted through the object, Laser Doppler velocimeters, laser interferometers, etc. are widely used in the fields of NC machine tools, OA equipment, robots, precision manufacturing equipment and the like. The present applicant has proposed an example of such an optical displacement measuring device in Japanese Patent Application Laid-Open No. 5-340719 and Japanese Patent Application No. 4-347414.

【０００３】上記の光学式変位測定装置は、使用に際し
て通常図７に図示するように配置する。図に於いて５０
と６０は相対的な変位情報を得たい２つの物体であり、
物体５０は固定され、物体６０がステージにより図の矢
印方向に移動する。３０は光学ヘッドであり、これは発
光素子、レンズ、光束分割用回折格子，光束重畳用回折
格子、受光素子及び制御演算回路などを一つの筐体に収
めている。４０は電源供給や信号の取り出しのためのケ
ーブルである。In use, the above optical displacement measuring device is usually arranged as shown in FIG. 50 in the figure
And 60 are two objects for which relative displacement information is desired,
The object 50 is fixed, and the object 60 moves in the direction of the arrow in the figure by the stage. An optical head 30 includes a light emitting element, a lens, a light beam splitting diffraction grating, a light beam superimposing diffraction grating, a light receiving element, a control arithmetic circuit, and the like in one housing. Reference numeral 40 is a cable for power supply and signal extraction.

【０００４】変位情報の検出に際しては、回折格子２１
が形成されたスケール２０を移動物体６０に、又ヘッド
３０は固定物体５０に所定の間隔を確保して取り付けて
測定する。When detecting the displacement information, the diffraction grating 21 is used.
The scale 20 on which the marks are formed is attached to the moving object 60, and the head 30 is attached to the fixed object 50 with a predetermined space therebetween, and the scale is measured.

【０００５】[0005]

【発明が解決しようとする課題】これらで提案している
光学式変位測定装置は、物体に設けたスケール２０を介
した２光束の干渉を光学ヘッドで検出し、これによって
該物体と光学ヘッドとの相対的な変位情報を得ている。
そこで、２つの光束に波面形状の違い・光路長差・重な
りのずれ等があれば、受光素子に入射する光束の断面方
向に干渉縞が発生し、本来の振幅や位相差を有する信号
が得られなくなってしまうおそれがある。そこで、かか
る光学式変位測定装置の実用化に際してはこれらの影響
を的確に把握し、適用する機器に応じて最適な設計をす
る必要がある。The optical displacement measuring devices proposed by these methods detect the interference of two light beams through the scale 20 provided on the object with the optical head, and thereby the object and the optical head are detected. The relative displacement information of is obtained.
Therefore, if there is a difference in wavefront shape, difference in optical path length, shift in overlap, etc. between the two light beams, interference fringes are generated in the cross-sectional direction of the light beams entering the light receiving element, and a signal having the original amplitude or phase difference is obtained. There is a risk that you will not be able to. Therefore, when putting such an optical displacement measuring device into practical use, it is necessary to accurately grasp these influences and make an optimum design according to the applied device.

【０００６】エアステージのように精度良く走行するも
のに適用する場合は、スケールと光学ヘッドの位置関係
が理想に近い状態が保たれるので、上記のような問題が
生じるおそれはほとんどないが、スケールの送り精度が
良くない物体へ適用する場合には重大な問題となる。例
えば図８に示すようにスケール２０の送り精度が良くな
い場合、光学ヘッド３０を基準に考えるとスケール２０
の相対的送り誤差は同図に示すようにＸ，Ｙ，Ｚ各軸の
回りの回転及びギャップの変動として発生する。そこ
で、使用される送り手段によってスケール２０が構造的
にどの種類の送り誤差が生じ易いかということを配慮し
て、光学式変位測定装置の設計を行なわなければならな
い。When applied to an object that travels with high precision such as an air stage, since the positional relationship between the scale and the optical head is maintained close to the ideal state, the above problems are unlikely to occur. This is a serious problem when applied to an object with a poor scale feed accuracy. For example, as shown in FIG. 8, when the feed accuracy of the scale 20 is not good, when the optical head 30 is used as a reference, the scale 20
The relative feed error of occurs as rotation around the X, Y, and Z axes and fluctuation of the gap as shown in FIG. Therefore, it is necessary to design the optical displacement measuring device in consideration of what kind of feed error the scale 20 is structurally likely to cause depending on the feed means used.

【０００７】本発明は、スケール送り機構の精度特性に
よって種々な干渉縞が発生しても、十分な振幅の干渉信
号が容易に得られ、安定して高精度の変位情報が得られ
る、使い易い、種々な用途に適用可能な光学式変位測定
装置の提供を目的とする。According to the present invention, even if various interference fringes are generated due to the accuracy characteristics of the scale feed mechanism, an interference signal having a sufficient amplitude can be easily obtained, stable and highly accurate displacement information can be obtained, and it is easy to use. An object of the present invention is to provide an optical displacement measuring device applicable to various uses.

【０００８】[0008]

【課題を解決するための手段】本発明の光学式変位測定
装置は、 （１−１） 相対移動する物体間を介した２光束に基づ
く干渉情報を受光素子で検出し、該受光素子からの信号
を用いて演算手段により該物体間の変位情報を求める
際、該受光素子は複数の受光セルを有しており、該演算
手段は該複数の受光セルのうち所定の受光セルからの信
号を用いていることを特徴としている。特に、（１−１
−１） 前記演算手段は設定手段からの信号に基づいて
前記複数の受光セルのうちから所定の受光セルの信号を
選択して用いている、（１−１−２） 前記設定手段を
光学式変位測定装置の一要素を構成する発光素子、光束
分割用回折格子、光束重畳用回折格子及び受光素子等を
収めた筐体より離れた位置に設置している、こと等を特
徴としている。The optical displacement measuring apparatus of the present invention comprises: (1-1) Detecting interference information based on two light fluxes between relatively moving objects with a light receiving element, and detecting the interference information from the light receiving element. When the displacement information between the objects is obtained by the calculating means using the signal, the light receiving element has a plurality of light receiving cells, and the calculating means obtains a signal from a predetermined light receiving cell among the plurality of light receiving cells. It is characterized by being used. In particular, (1-1
-1) The calculating means selects and uses a signal of a predetermined light receiving cell from the plurality of light receiving cells based on a signal from the setting means, (1-1-2) the setting means is an optical type It is characterized in that the displacement measuring device is installed at a position apart from a housing containing a light emitting element, a light beam splitting diffraction grating, a light beam superimposing diffraction grating, a light receiving element, and the like, which constitute one element.

【０００９】[0009]

【実施例】図１は本発明の実施例１の要部概略図を示す
ものである。同図において、１は発光素子であり、半導
体レーザや発光ダイオード等から構成されている。２は
レンズであり、発光素子１から放射される光を略平行光
束に変換する。３Ａは光束分割用の回折格子であり、２
１は被測定物に取り付けたスケール２０に設置した回折
格子であり、３Ｃは光束重畳用の回折格子（４分割回折
格子）である。３つの回折格子は全て同じピッチ（たと
えば１．６μｍ）であり、夫々の格子線方向及び格子配
列方向も同じである。Embodiment 1 FIG. 1 is a schematic view of the essential portions of Embodiment 1 of the present invention. In the figure, reference numeral 1 denotes a light emitting element, which is composed of a semiconductor laser, a light emitting diode, or the like. Reference numeral 2 denotes a lens, which converts the light emitted from the light emitting element 1 into a substantially parallel light flux. 3A is a diffraction grating for splitting a light beam,
Reference numeral 1 is a diffraction grating installed on a scale 20 attached to the object to be measured, and 3C is a diffraction grating for superimposing light beams (four-division diffraction grating). All the three diffraction gratings have the same pitch (for example, 1.6 μm), and their respective grating line directions and grating arrangement directions are also the same.

【００１０】本実施例では格子ピッチをＰ，格子線方向
をＹ方向、格子配列方向をＸ方向とする。回折格子３Ｃ
は図３に示すように４つの部分３Ｃ１，３Ｃ２，３Ｃ
３，３Ｃ４から構成しており、夫々は同図に示すように
1/4 ピッチづつずれており、これによって相互にπ/2の
波面位相差が付くように構成している。４Ｃは受光素子
であり、これは図２（Ａ）に示すように４つの受光素子
４Ｃ１，４Ｃ２，４Ｃ３，４Ｃ４から構成しており、更
に各受光素子４Ｃ１〜４Ｃ４は夫々４つの受光セルａ，
ｂ，ｃ，ｄから構成している。In this embodiment, the lattice pitch is P, the lattice line direction is the Y direction, and the lattice arrangement direction is the X direction. Diffraction grating 3C
Are four parts 3C1, 3C2, 3C as shown in FIG.
3 and 3C4, each as shown in the figure.
They are offset by 1/4 pitch, and they are configured to have a wavefront phase difference of π / 2 with each other. 4C is a light receiving element, which is composed of four light receiving elements 4C1, 4C2, 4C3, 4C4 as shown in FIG. 2A, and each of the light receiving elements 4C1 to 4C4 has four light receiving cells a,
It is composed of b, c and d.

【００１１】発光素子１、レンズ２、回折格子３Ａ，３
Ｃ、受光素子４Ｃ等は筐体内に収納されて、光学ヘッド
３０の一要素を構成している。Light emitting element 1, lens 2, diffraction gratings 3A, 3
C, the light-receiving element 4C, and the like are housed in a housing and form one element of the optical head 30.

【００１２】次に本実施例の動作を説明する。発光素子
１を出てレンズ２によって略平行にされた光束は回折格
子３Ａに入射する。この光束はここで透過回折され、０
次回折光R0、−１次回折光R-1 の２つを含む複数の光束
に分かれ、スケール上に形成された回折格子２１に入射
する。直進した０次回折光R0は回折格子２１に入射（光
束の中心光線は点Ｐ１に入射する）して、そこで反射回
折されて＋１次回折光R0+1、−１次回折光R0-1等に分割
されると同時にそれぞれは位相変調される。即ち回折格
子２１がx だけ相対移動すると、各光束の位相は-2πx/
P だけずれる。次いで、上記の複数の回折光のうち−１
次回折光R0-1は回折格子３Ｃにて透過回折を受け、０次
回折光R0-10 、＋１次回折光R0-1+1等に分割される。こ
のうち＋１次回折光R0-1+1は、回折格子３Ｃ面から垂直
に出射し、その波面の位相は基本的に-2πx/P だけずれ
ている。Next, the operation of this embodiment will be described. The light flux emitted from the light emitting element 1 and made substantially parallel by the lens 2 enters the diffraction grating 3A. This light beam is transmitted and diffracted here, and 0
It is divided into a plurality of light fluxes including the two-order diffracted light R0 and the minus first-order diffracted light R-1 and is incident on the diffraction grating 21 formed on the scale. The straight-ahead 0th-order diffracted light R0 is incident on the diffraction grating 21 (the central ray of the light flux is incident on the point P1), and is reflected and diffracted there to be split into + 1st-order diffracted light R0 + 1, -1st-order diffracted light R0-1 and the like. At the same time, each is phase-modulated. That is, when the diffraction grating 21 relatively moves by x, the phase of each light beam is -2πx /
Only P shifts. Then, among the plurality of diffracted lights above, -1
The order diffracted light R0-1 is transmitted and diffracted by the diffraction grating 3C, and is divided into 0th order diffracted light R0-10, + 1st order diffracted light R0-1 + 1, and the like. Of these, the + 1st order diffracted light R0-1 + 1 is emitted perpendicularly from the surface of the diffraction grating 3C, and the phase of its wavefront is basically shifted by -2πx / P.

【００１３】ところで、回折格子３Ｃを構成する３Ｃ１
〜３Ｃ４の格子配列の位相はP/4 ずつずらしているの
で、上記の回折光R0-1+1は４つに分かれ夫々の波面の位
相はさらに-2π・(1/4)＝ -π/2ずつずれる。したがっ
て、３Ｃ１〜３Ｃ４の各回折格子を通過した波面の位相
のずれは次のようになる。By the way, 3C1 which constitutes the diffraction grating 3C
Since the phase of the lattice array of ~ 3C4 is shifted by P / 4, the above diffracted light R0-1 + 1 is divided into four and the phase of each wavefront is further -2π ・ (1/4) = -π / Shift by 2 Therefore, the phase shift of the wavefront that has passed through the diffraction gratings 3C1 to 3C4 is as follows.

【００１４】３Ｃ１ ： -2πx/P ３Ｃ２ ： -2πx/P-π/2 ３Ｃ３ ： -2πx/P-π ３Ｃ４ ： -2πx/P- 3π/2 一方、回折格子３Ａにて−１次回折した光束R-1 は、ス
ケール２０上の回折格子２１に入射（光束の中心光線は
点Ｐ２に入射する）して、そこで反射回折されて、＋１
次回折光R-1+1 、０次回折光R-10およびその他の光束に
分割され、同時にそれぞれ位相変調される。このうち、
＋１次回折光R-1+1 はその位相が+2πx/P だけずれて回
折格子３Ｃに入射し、そこで透過回折を受ける。その
内、そのまま直進した０次回折光R-1+10の波面の位相は
基本的に+2πx/P だけずれている。そして、この光束は
回折格子３Ｃ１〜３Ｃ４によって４つに分けられ、夫々
は更に-2π・(1/4)づつ位相がずれる。3C1: -2πx / P 3C2: -2πx / P-π / 2 3C3: -2πx / P-π 3C4: -2πx / P-3π / 2 On the other hand, the light beam diffracted by the diffraction grating 3A in the -1st order R-1 is incident on the diffraction grating 21 on the scale 20 (the central ray of the light flux is incident on the point P2), is reflected and diffracted there, and is +1.
The light is split into a first-order diffracted light R-1 + 1, a 0th-order diffracted light R-10, and other light beams, which are simultaneously phase-modulated. this house,
The + 1st-order diffracted light R-1 + 1 enters the diffraction grating 3C with its phase shifted by + 2πx / P and undergoes transmission diffraction there. Among them, the phase of the wavefront of the 0th-order diffracted light R-1 + 10 that has proceeded straight as it is is basically shifted by + 2πx / P. Then, this light beam is divided into four by the diffraction gratings 3C1 to 3C4, and the phases thereof are further shifted by −2π · (1/4).

【００１５】回折格子３Ｃ１〜３Ｃ４にて光路を重ね合
わされた光束R-1+10と光束R0-1+1は、干渉光となって、
受光素子４Ｃに入射する。このとき受光素子４Ｃ１、４
Ｃ２、４Ｃ３、４Ｃ４に入射する２つの干渉光の位相差
は、それぞれ、 （-2πx/P)-(+2πx/P)＝-4πx/P （-2πx/P-π/2)-( +2πx/P)＝-4πx/P-π/2 （-2πx/P-π)-( +2πx/P)＝-4πx/P-π （-2πx/P- 3π/2)-( +2πx/P)＝-4πx/P- 3π/2 となり、受光素子４Ｃ１〜４Ｃ４の１つ１つからはスケ
ール上の回折格子２１が1/2 ピッチ移動するごとに１周
期の明暗信号が発生し、更に受光素子４Ｃ１〜４Ｃ４相
互では位相が夫々1/4 周期だけずれた信号が得られる。The light beam R-1 + 10 and the light beam R0-1 + 1 whose optical paths are superposed by the diffraction gratings 3C1 to 3C4 become interference light,
It is incident on the light receiving element 4C. At this time, the light receiving elements 4C1, 4
The phase difference between the two interference lights incident on C2, 4C3, and 4C4 is (-2πx / P)-(+ 2πx / P) =-4πx / P (-2πx / P-π / 2)-(+ 2πx / P) ＝-4πx / P-π / 2 (-2πx / P-π)-(+ 2πx / P) ＝-4πx / P-π (-2πx / P-3π / 2)-(+ 2πx / P) = − 4πx / P−3π / 2, and one light / dark signal is generated from each of the light receiving elements 4C1 to 4C4 each time the diffraction grating 21 on the scale moves by 1/2 pitch. The light receiving elements 4C1 to 4C4 can obtain signals whose phases are shifted by 1/4 cycle.

【００１６】以上のようにして、スケール２０の変位に
伴って、受光素子４Ｃ１〜４Ｃ４から1/4 周期ずつずれ
た周期信号が得られる。これをもとに、不図示の演算手
段により光学ヘッド３０とスケール２０との相対的な変
位量を演算して求めている。As described above, with the displacement of the scale 20, periodic signals deviated from the light receiving elements 4C1 to 4C4 by 1/4 period are obtained. Based on this, a relative displacement amount between the optical head 30 and the scale 20 is calculated by a calculation means (not shown).

【００１７】図２は本実施例の受光素子の説明図であ
る。演算手段は図２（Ａ）に示す４つの受光セルａ、
ｂ、ｃ、ｄからの受光信号のうち、どの信号を用いて演
算するかを選択して演算する。本実施例において、２光
束の干渉によって例えば縦方向の干渉縞が生じた場合、
受光素子４Ｃ上には例えば図２（Ｂ）のような干渉縞が
発生する。この場合、演算手段が受光セルａ，ｂ，ｃ，
ｄ全ての受光信号を用いるように選択すれば、各受光セ
ルからの信号が平均化され、受光素子からの信号の振幅
が小さくなってしまう。しかしながら、この場合に演算
手段が受光素子４Ｃ１〜４Ｃ４夫々の中の受光セルａと
ｃ（または受光セルｂとｄ）の部分のみからの受光信号
を選択すれば、この部分では干渉縞の発生度合いが小さ
いので信号の振幅は大きくなり、位相差も明確に付けら
れる。また、受光部４Ｃの実効面積は全面積の１／２程
度なので、受光光量が半減する程度でありS/N 比も十分
確保することができる。FIG. 2 is an explanatory view of the light receiving element of this embodiment. The calculation means is composed of four light receiving cells a shown in FIG.
Of the received light signals from b, c, and d, which signal is used for calculation is selected and calculated. In the present embodiment, for example, when interference of two light beams causes interference fringes in the vertical direction,
For example, interference fringes as shown in FIG. 2B are generated on the light receiving element 4C. In this case, the calculation means is the light receiving cells a, b, c,
If all the light receiving signals are selected to be used, the signals from the respective light receiving cells are averaged and the amplitude of the signal from the light receiving element becomes small. However, in this case, if the calculation means selects the light receiving signal from only the light receiving cells a and c (or the light receiving cells b and d) in each of the light receiving elements 4C1 to 4C4, the degree of occurrence of interference fringes in this portion. Is small, the amplitude of the signal is large and the phase difference is clearly added. Further, since the effective area of the light receiving portion 4C is about 1/2 of the total area, the amount of received light is reduced to half and the S / N ratio can be sufficiently secured.

【００１８】本実施例の場合、Ｙ軸を軸とする回転送り
誤差（回転角）がある場合には縦縞が発生し、Ｚ軸を軸
とする回転送り誤差（アジマス角）がある場合には横縞
が発生することが判っている。したがって、スケール送
り精度が、機構上、回転角を発生し易い場合は受光セル
ａとｃ（または受光セルｂとｄ）、アジマス角を発生し
易い場合は受光セルａとｂ（または受光セルｃとｄ）か
らの受光信号を選択することにより、この場合でも大き
い振幅の信号が得られる。In the case of the present embodiment, vertical stripes occur when there is a rotational feed error (rotation angle) about the Y axis, and when there is a rotational feed error (azimuth angle) about the Z axis. It is known that horizontal stripes occur. Therefore, if the scale feed accuracy is such that the rotation angle is likely to occur due to the mechanism, the light receiving cells a and c (or the light receiving cells b and d) may be generated, and if the azimuth angle is likely to occur, the light receiving cells a and b (or the light receiving cell c). By selecting the light receiving signals from the signals d and d), a signal with a large amplitude can be obtained even in this case.

【００１９】さらに、Ｘ軸を軸とする回転送り誤差（ア
オリ角）が発生した場合には、干渉２光束の重なりがず
れて光束の上下の周辺で干渉信号が得られなくなるの
で、この場合も前と同様に光束の上下方向の中央付近を
受光するように受光セルを選択（たとえば、受光素子４
Ｃ１、４Ｃ２では受光セルｃとｄ、受光素子４Ｃ３，４
Ｃ４では受光セルａとｂ）して使用するとよい。Further, when a rotational feed error (tilt angle) about the X-axis occurs, the overlapping of the two interference light beams is deviated and the interference signals cannot be obtained around the upper and lower parts of the light beams. As in the previous case, the light receiving cells are selected so as to receive light near the vertical center of the light flux (for example, the light receiving element 4
In C1, 4C2, the light receiving cells c and d, and the light receiving elements 4C3, 4
In C4, the light receiving cells a and b) may be used.

【００２０】また、固定回折格子と移動回折格子のギャ
ップが変動すれば干渉をする２光束の重なりがずれて光
束の左右周辺で干渉信号が得られなくなるので、ギャッ
プが変動しやすい場合は、光束の左右方向の中央付近を
受光するように受光セルを選択し（たとえば、受光素子
４Ｃ１、４Ｃ３では受光セルｂとｄ、受光素子４Ｃ２、
４Ｃ４では受光セルａとｃ）使用するとよい。Further, if the gap between the fixed diffraction grating and the moving diffraction grating fluctuates, the overlapping of the two light beams that interfere with each other shifts and an interference signal cannot be obtained around the left and right sides of the light beam. The light receiving cells are selected so as to receive light in the vicinity of the center in the left-right direction (for example, in the light receiving elements 4C1 and 4C3, the light receiving cells b and d, the light receiving element 4C2,
In 4C4, it is preferable to use the light receiving cells a and c).

【００２１】以上のように本実施例によればスケール２
０の送り機構の精度が多少良くない移動物体を計測する
場合でも、発生する干渉縞に応じて演算手段が受光セル
からの信号を選択するように構成していることにより大
きい振幅の信号が得られ、これによって安定して高い精
度の計測が達成できる。As described above, according to this embodiment, the scale 2
Even when measuring a moving object in which the accuracy of the 0 feed mechanism is not so good, a signal having a larger amplitude can be obtained because the arithmetic means is configured to select the signal from the light receiving cell according to the generated interference fringe. As a result, stable and highly accurate measurement can be achieved.

【００２２】なお、回折格子と受光素子間の距離や光束
の状況（発散・収束状況）によっては、レンズを追加し
たり省略したりする。A lens may be added or omitted depending on the distance between the diffraction grating and the light receiving element and the condition of the light beam (divergence / convergence condition).

【００２３】図４は、本発明の実施例１における信号処
理回路の説明図である。この信号処理回路は演算手段の
一部であり、４つの受光素子の夫々に設けている。この
回路では、受光セルａ、ｂ、ｃ、ｄのアノードはコモン
となっており、各受光セルのカソード側には各受光セル
に対応してアナログスイッチ１０１（４回路入り）を接
続している。そして演算増幅器１０２、抵抗Ｒとで、受
光電流を電圧に変換し、出力端子１０３に導出する。キ
ャパシタＣはフィードバック系の安定度を確保するため
に使用している。一方、受光セル選択端子１０４〜１０
７は各々ＨｉｇｈまたはＬｏｗの受光セル選択信号を設
定する設定手段に繋がっており、スケール２０の送り手
段に応じて設定手段を適切にセットしてアナログスイッ
チ４回路のＯＮ、ＯＦＦの組合せを決定する。これによ
り、受光セルａ，ｂ，ｃ，ｄのうち受光信号を取り出す
受光セルの組合せを任意に選択することができる。FIG. 4 is an explanatory diagram of a signal processing circuit according to the first embodiment of the present invention. This signal processing circuit is a part of the calculating means and is provided in each of the four light receiving elements. In this circuit, the anodes of the light receiving cells a, b, c, d are common, and the analog switch 101 (with four circuits) corresponding to each light receiving cell is connected to the cathode side of each light receiving cell. . Then, the operational amplifier 102 and the resistor R convert the received light current into a voltage and lead it to the output terminal 103. The capacitor C is used to ensure the stability of the feedback system. On the other hand, the light receiving cell selection terminals 104 to 10
Reference numeral 7 is connected to setting means for setting a high or low light receiving cell selection signal, and the setting means is appropriately set according to the feeding means of the scale 20 to determine the ON / OFF combination of the analog switch 4 circuits. . As a result, it is possible to arbitrarily select a combination of the light receiving cells from which the light receiving signal is extracted among the light receiving cells a, b, c and d.

【００２４】このような構成を用いれば、移動物体の移
動機構の特性上発生しやすい干渉縞の方向に対応して受
光セル選択端子１０４〜１０７を設定することにより、
適用対象に最適な光学式変位測定装置を達成できる。With such a configuration, by setting the light receiving cell selection terminals 104 to 107 in correspondence with the direction of the interference fringes that are likely to occur due to the characteristics of the moving mechanism of the moving object,
It is possible to achieve an optimal optical displacement measuring device for an application target.

【００２５】更に、前記の設定手段を光学式変位測定装
置のヘッド３０から離れた位置に構成すれば、本装置の
使用者が、変位情報を検出する移動物体の移動機構に応
じてその都度最適な受光セルからの受光信号の選択を外
部から設定することができる。Further, if the setting means is arranged at a position away from the head 30 of the optical displacement measuring device, the user of the device is optimized each time according to the moving mechanism of the moving object for detecting the displacement information. It is possible to externally set the selection of the light reception signal from each light reception cell.

【００２６】図５は本発明の実施例２及び３に係る受光
素子の複数の受光セルの配置に関する概略図である。受
光セルの数は実施例１の場合は４個用いたが、数に限定
されず、実施例２及び３のように３つ又は８つ等任意の
数に設定し得る。本発明に係る受光素子を構成する受光
セルの数は適用対象に応じて適宜、最適に設定すればよ
い。この例では、光束の外周周辺にあたる光量の小さい
部分は受光セルを省いている。FIG. 5 is a schematic view of the arrangement of a plurality of light receiving cells of the light receiving element according to the second and third embodiments of the present invention. Although the number of the light receiving cells is four in the case of the first embodiment, it is not limited to the number and can be set to any number such as three or eight as in the second and third embodiments. The number of light-receiving cells forming the light-receiving element according to the present invention may be set appropriately and optimally depending on the application target. In this example, the light-receiving cell is omitted in a portion having a small amount of light, which corresponds to the periphery of the light flux.

【００２７】また、信号処理回路の構成も図４の例に限
定されず、さまざまな構成が考えられる。アナログスイ
ッチを用いずに個々の受光セルの配線を変更する構成に
しても良い（図示せず）。また、図６の信号処理回路の
ように、各受光セルからの受光電流を個別に電圧変換し
てからアナログスイッチ１０１によって選択し、合成す
る方法をとっても良い。この例では、アナログスイッチ
１０１によって受光セルを選択したあと、演算増幅器１
０８を用いたバッファを通して信号を出力している。本
実施例の信号処理回路では受光セル選択端子は１０４、
１０５の２端子しかないが、論理回路１０９によってあ
らかじめ設定された４通りの組合せから最適な組合せを
選択することができるようにしたものである。The configuration of the signal processing circuit is not limited to the example shown in FIG. 4, and various configurations are conceivable. The wiring of each light receiving cell may be changed without using an analog switch (not shown). Further, as in the signal processing circuit of FIG. 6, a method may be adopted in which the light receiving currents from the respective light receiving cells are individually voltage-converted and then selected by the analog switch 101 and combined. In this example, after the light receiving cell is selected by the analog switch 101, the operational amplifier 1
The signal is output through the buffer using 08. In the signal processing circuit of this embodiment, the light receiving cell selection terminal is 104,
Although there are only two terminals 105, the optimum combination can be selected from the four combinations preset by the logic circuit 109.

【００２８】なお、本発明は、上記説明で用いた光学系
に限らず、２光束の干渉により発生する光束の明暗を受
光素子によって計測し、これを利用する光学式変位測定
装置であれば同じ様に適用することができる。又受光素
子としては４Ｃ１〜４Ｃ４の４チャンネルがある場合に
ついて述べたが、受光チャンネルの数はいくつであって
も適用可能である。受光素子及び受光セルの形状や極性
なども限定されない。The present invention is not limited to the optical system used in the above description, and the same applies to an optical displacement measuring device that measures the brightness of a light beam generated by the interference of two light beams with a light receiving element and uses this. Can be applied to Although the case where there are four channels 4C1 to 4C4 as the light receiving element has been described, the invention can be applied regardless of the number of light receiving channels. The shapes and polarities of the light receiving element and the light receiving cell are not limited.

【００２９】また、説明で用いた直線型の光学式変位測
定装置に限定されず、回転型変位センサ、速度測定装
置、加速度測定装置、測長装置など、２光束の干渉によ
って明暗が生じることを利用して変位情報を得る装置お
よびその応用装置であれば、同様に適用可能である。Further, the invention is not limited to the linear type optical displacement measuring device used in the description, but it is possible to use a rotary displacement sensor, a velocity measuring device, an acceleration measuring device, a length measuring device, etc. to produce light and dark due to interference of two light beams. The same is applicable to any device that obtains displacement information by utilizing the device and its applied device.

【００３０】[0030]

【発明の効果】本発明は以上のように各要素を構成した
ので、スケール送り機構の精度特性によって干渉縞が発
生しても、十分な振幅の干渉信号が得られ、安定して高
精度の変位情報が得られる、使い易い、種々な用途に最
適な光学式変位測定装置を達成している。Since each element of the present invention is configured as described above, even if interference fringes are generated due to the precision characteristics of the scale feed mechanism, an interference signal having a sufficient amplitude can be obtained and stable and high precision can be obtained. We have achieved an optical displacement measuring device that can obtain displacement information, is easy to use, and is optimal for various applications.

【００３１】更に、受光セルからの受光信号を選択する
設定手段を光学式変位測定装置の光学ヘッドから離れた
位置に構成すれば、本測定装置の使用者が、変位情報を
検出する移動物体の移動機構に応じてその都度最適な受
光セルからの受光信号の選択を外部から設定することが
できる。Further, if the setting means for selecting the light receiving signal from the light receiving cell is arranged at a position away from the optical head of the optical displacement measuring device, the user of the measuring device can detect the displacement information of the moving object. The optimum selection of the light receiving signal from the light receiving cell can be set from the outside depending on the moving mechanism.

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

【図１】 本発明の実施例１の要部概略図FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

【図２】 本発明の実施例１の受光素子の説明図 （Ａ）受光素子の配置 （Ｂ）干渉光束FIG. 2 is an explanatory diagram of a light receiving element according to the first embodiment of the present invention. (A) Arrangement of light receiving elements (B) Interfering light flux

【図３】 ４分割回折格子の説明図FIG. 3 is an explanatory diagram of a four-division diffraction grating

【図４】 本発明の実施例１における信号処理回路FIG. 4 is a signal processing circuit according to the first embodiment of the present invention.

【図５】 本発明の実施例２及び３に係る複数の受光セ
ルの配置に関する概略図FIG. 5 is a schematic view of an arrangement of a plurality of light receiving cells according to second and third embodiments of the present invention.

【図６】 本発明の実施例における信号処理回路の別の
例FIG. 6 is another example of the signal processing circuit according to the embodiment of the present invention.

【図７】 光学式変位測定装置の使用状態を説明する図FIG. 7 is a diagram illustrating a usage state of the optical displacement measuring device.

【図８】 光学式変位測定装置におけるスケールの取付
誤差を説明する図FIG. 8 is a diagram for explaining a scale mounting error in the optical displacement measuring device.

【符号の説明】[Explanation of symbols]

１ 光源 ２ レンズ ３Ａ 光束分割用の回折格子 ２１ スケールに設置した回折格子 ３Ｃ、（３Ｃ１，３Ｃ２，３Ｃ３，３Ｃ４） 光束重畳
用の回折格子 ４Ｃ、（４Ｃ１，４Ｃ２，４Ｃ３，４Ｃ４） 受光素子 ａ，ｂ，ｃ，ｄ 受光セル ２０ スケール ３０ 光学ヘッド ５０ 物体（固定） ６０ 物体（移動） １０１ アナログスイッチ １０２ 演算増幅器 １０３ 出力端子 １０４〜１０７ 受光セル選択端子 １０８ 演算増幅器 １０９ 論理回路DESCRIPTION OF SYMBOLS 1 Light source 2 Lens 3A Diffraction grating for splitting light flux 21 Diffraction grating 3C installed on a scale, (3C1, 3C2, 3C3, 3C4) Diffraction grating 4C for superimposing light flux, (4C1, 4C2, 4C3, 4C4) Light receiving element a, b, c, d light receiving cell 20 scale 30 optical head 50 object (fixed) 60 object (moving) 101 analog switch 102 operational amplifier 103 output terminal 104 to 107 light receiving cell selection terminal 108 operational amplifier 109 logic circuit

───────────────────────────────────────────────────── フロントページの続き (72)発明者 久本 憲司 東京都大田区下丸子３丁目30番２号 キヤ ノン株式会社内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Hisamoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (3)

【特許請求の範囲】[Claims] 【請求項１】 相対移動する物体間を介した２光束に基
づく干渉情報を受光素子で検出し、該受光素子からの信
号を用いて演算手段により該物体間の変位情報を求める
際、 該受光素子は複数の受光セルを有しており、該演算手段
は該複数の受光セルのうち所定の受光セルからの信号を
用いていることを特徴とする光学式変位測定装置。1. When the light receiving element detects interference information based on two light beams passing through relatively moving objects and the displacement information between the objects is obtained by a calculation means using a signal from the light receiving element, the received light is detected. The element has a plurality of light receiving cells, and the arithmetic means uses a signal from a predetermined light receiving cell among the plurality of light receiving cells. 【請求項２】 前記演算手段は設定手段からの信号に基
づいて前記複数の受光セルのうちから所定の受光セルの
信号を選択して用いていることを特徴とする請求項１の
光学式変位測定装置。2. The optical displacement according to claim 1, wherein the arithmetic means selects and uses a signal of a predetermined light receiving cell from the plurality of light receiving cells based on a signal from the setting means. measuring device. 【請求項３】 前記設定手段を光学式変位測定装置の一
要素を構成する発光素子、光束分割用回折格子、光束重
畳用回折格子及び受光素子等を収めた筐体より離れた位
置に設置していることを特徴とする請求項２の光学式変
位測定装置。3. The setting means is installed at a position distant from a housing containing a light emitting element, a light beam splitting diffraction grating, a light beam superimposing diffraction grating, a light receiving element, etc., which constitute one element of the optical displacement measuring device. The optical displacement measuring device according to claim 2, wherein