JP2011013116A

JP2011013116A - Encoder

Info

Publication number: JP2011013116A
Application number: JP2009158140A
Authority: JP
Inventors: Hayami Kikawa; 速見木川
Original assignee: Sokkia Topcon Co Ltd
Current assignee: Sokkia Topcon Co Ltd
Priority date: 2009-07-02
Filing date: 2009-07-02
Publication date: 2011-01-20
Anticipated expiration: 2029-07-02
Also published as: JP5137907B2

Abstract

PROBLEM TO BE SOLVED: To prevent any error in an angle measurement value from occurring in an encoder, even when a line sensor tilts with respect to a plane which intersects the rotary shaft of a dial perpendicularly.SOLUTION: The encoder includes the dial (3), where an angle scale (32) and a concentric circle pattern (33) which are formed along the angle scale and concentric with the angle scale; the line sensor (23) for reading the angle scale; and an arithmetic means (5) for obtaining the angle measurement value, by carrying out an interpolation calculation on the basis of the read angle scale. At shipping of the encoder, actual-angle reading position on the line sensor is varied according to an angle produced by the line sensor and the plane which perpendicularly intersects with the rotary shaft of the dial.

Description

本発明は、測量機に備られるエンコーダに関し、さらに詳細には、角度目盛を読み取るラインセンサが目盛盤の回転軸に直交する平面に対して傾いている場合でも測角値に誤差が生じないようにしたエンコーダに関する。 The present invention relates to an encoder provided in a surveying instrument. More specifically, even if a line sensor that reads an angle scale is inclined with respect to a plane perpendicular to the rotary axis of the scale plate, no error occurs in the angle measurement value. Relates to the encoder.

測量機には、水平角と鉛直角を測定するために、エンコーダが備えられている。従来のエンコーダとしては、下記特許文献１に開示されたようなものが知られている。図１に示したように、このエンコーダ１は、望遠鏡とともに回転する目盛盤３があり、目盛盤３の周方向に沿って等間隔に設けられたスリット３２からなる角度目盛に対して、ＬＥＤ等の光源２１から出射された光をコリメータレンズ２２を介して照射し、スリット３２を通過した光をＣＣＤラインセンサ２３で受光し、ＣＣＤラインセンサ２３の出力をＣＰＵ（演算制御部）５へ送るものである。そして、ＣＰＵ５は、ＣＣＤラインセンサ２３の出力に基づいて水平角と鉛直角を決定する。 The surveying instrument is equipped with an encoder for measuring the horizontal angle and the vertical angle. As a conventional encoder, one disclosed in Patent Document 1 below is known. As shown in FIG. 1, the encoder 1 has a scale plate 3 that rotates together with the telescope, and an LED or the like with respect to an angle scale formed by slits 32 provided at equal intervals along the circumferential direction of the scale plate 3. The light emitted from the light source 21 is irradiated through the collimator lens 22, the light passing through the slit 32 is received by the CCD line sensor 23, and the output of the CCD line sensor 23 is sent to the CPU (calculation control unit) 5 It is. Then, the CPU 5 determines the horizontal angle and the vertical angle based on the output of the CCD line sensor 23.

エンコーダ１にはインクリメンタル式とアブソリュート式があるが、下記特許文献１に開示されたものは、アブソリュート式である。アブソリュート式エンコーダの目盛盤３には、図２に示したように、スリット３２が、太いスリット３２ａと細いスリット３２ｂとを組み合わせて配置されている。連続する所定本数のスリット３２を抜き出して読むと、太いスリット３２ａと細いスリット３２ｂの並び方から、角度を読み取れるようになっている。すなわち、各スリット３２は、所定の角度に対応している。 The encoder 1 includes an incremental type and an absolute type, but the one disclosed in Patent Document 1 below is an absolute type. As shown in FIG. 2, a slit 32 is arranged on the scale plate 3 of the absolute encoder in combination with a thick slit 32a and a thin slit 32b. When a predetermined number of continuous slits 32 are extracted and read, the angle can be read from the arrangement of the thick slits 32a and the thin slits 32b. That is, each slit 32 corresponds to a predetermined angle.

目盛盤３の角度は、ＣＣＤラインセンサ２３に沿う座標において、測定ごとに決定される角度読み取り位置で読む。角度読み取り位置を決定するには、目盛盤３にスリット３２を配置した円と同心の同心円パターン３３を形成する。そして、図３に示したように、ＣＣＤラインセンサ２３の出力から、ＣＣＤラインセンサ２３の受光領域中心線Ｄ（以下、単にＣＣＤラインセンサ２３と記載する。）と同心円パターン３３の交点Ａ、Ｂの座標Ｃ_１、Ｃ_２を求め、その中点Ｍの座標Ｃ_ｍを求めて、その中点Ｍを角度読み取り位置とする。このような角度読み取り位置を用いると、回転軸４に目盛盤３がいくらか偏心して取り付けられていたとしても、測角値に誤差が発生しない。 The angle of the dial 3 is read at an angle reading position determined for each measurement in coordinates along the CCD line sensor 23. In order to determine the angle reading position, a concentric pattern 33 concentric with the circle in which the slits 32 are arranged is formed on the scale plate 3. Then, as shown in FIG. 3, from the output of the CCD line sensor 23, the intersections A and B of the concentric pattern 33 with the center line D of the light receiving area of the CCD line sensor 23 (hereinafter simply referred to as the CCD line sensor 23). Coordinates C ₁ and C ₂ are obtained, the coordinates C _m of the midpoint M are obtained, and the midpoint M is set as the angle reading position. When such an angle reading position is used, even if the scale 3 is attached to the rotating shaft 4 with some eccentricity, no error occurs in the angle measurement value.

ところで、測量機は１”程度の角度分解能が要求されるが、１”間隔で目盛盤３にスリット３２を形成することは困難である。そこで、ロータリエンコーダでは、微小な角度分解能を達成するために、２つのスリット３２の間の角度については、内挿計算で求めている。内挿計算を行うには、ＣＣＤラインセンサ２３に投影された複数のスリット像を予め定めたモデルに当て嵌めて計算する。 By the way, the surveying instrument is required to have an angular resolution of about 1 ″, but it is difficult to form the slits 32 in the dial 3 at intervals of 1 ″. Therefore, in the rotary encoder, in order to achieve a minute angular resolution, the angle between the two slits 32 is obtained by interpolation calculation. In order to perform the interpolation calculation, the calculation is performed by fitting a plurality of slit images projected on the CCD line sensor 23 to a predetermined model.

この内挿計算に用いるモデルとして、下記特許文献２に開示されたモデルを説明する。このモデルは、図４に示したように、目盛盤３の平面図において、目盛盤３の中心ＯとＣＣＤラインセンサ２３との距離をＲ、目盛盤３の中心ＯからＣＣＤラインセンサ２３へ引いた垂線の足の位置をＰ、この位置の角度をＡとする。また、ｉ番目のスリットの位置をｐ_ｉ、この位置の角度をａ_ｉとする。三角形ｐ_ｉＯＰを考えると次式が成立し、これを内挿計算のモデルにしている。
ｐ_ｉ−Ｐ＝Ｒｔａｎ（ａ_ｉ−Ａ）（１） As a model used for this interpolation calculation, a model disclosed in Patent Document 2 below will be described. As shown in FIG. 4, this model draws the distance between the center O of the scale plate 3 and the CCD line sensor 23 in the plan view of the scale plate 3, and draws the distance from the center O of the scale plate 3 to the CCD line sensor 23. Let P be the position of the vertical leg and A be the angle of this position. The position of the i-th slit is p _i and the angle of this position is a _i . Considering the triangle p _i OP, the following equation is established, which is used as a model for interpolation calculation.
p _i −P = R tan (a _i −A) (1)

図４では、ｉ番目のスリットが１本しか描かれていないが、実際には複数のスリットがあるので、各スリットについて前記（１）式を作る。（１）式において、ｐ_ｉとａ_ｉは既知であり、未知数はＰ、Ｒ、Ａの３つであるから、（１）式を３つ作れば、Ｐ、Ｒ、Ａを求めることができる。実際には、（１）式を４つ以上作ることができるので、回帰分析（最小二乗法）によって、Ｐ、Ｒ、Ａの最確値Ｐ’、Ｒ’、Ａ’を求める。このＰ’を角度読み取り位置としてもよいが、通常は、９０°おきにＰ’を求め、４つのＰ’の平均に基づいて、角度読み取り位置Ｐｒを決めている。この角度読み取り位置Ｐｒは、工場で一旦設定されると、その後変更されることはない。 In FIG. 4, although only one i-th slit is drawn, since there are actually a plurality of slits, the above equation (1) is made for each slit. In equation (1), p _i and a _i are known, and there are three unknowns, P, R, and A. Therefore, if three equations (1) are made, P, R, and A can be obtained. . Actually, since four or more equations (1) can be created, the most probable values P ′, R ′, and A ′ of P, R, and A are obtained by regression analysis (least square method). Although this P ′ may be used as the angle reading position, normally, P ′ is obtained every 90 °, and the angle reading position Pr is determined based on the average of the four P ′. This angle reading position Pr is not changed thereafter once set at the factory.

なお、後記特許文献１に開示されたものでは、前述したように、同心円パターン３３とＣＣＤラインセンサ２３との交点Ａ、Ｂの座標Ｃ１，Ｃ２の中点Ｍを角度読み取り位置としており、前述したように、測定ごとに角度読み取り位置が変更される。 In addition, in what was disclosed in Patent Document 1 described later, as described above, the midpoint M of the coordinates C1 and C2 of the intersections A and B of the concentric circle pattern 33 and the CCD line sensor 23 is set as the angle reading position. As described above, the angle reading position is changed for each measurement.

測角時には、ＣＣＤラインセンサ２３上のスリット像の位置から、前述した回帰分析によって最確値Ｐ’、Ｒ’、Ａ’を求めている。そこで、（１）式おいて、ｐ_ｉ＝Ｐｒ、Ｐ＝Ｐ’、Ｒ＝Ｒ’、Ａ＝Ａ’とするとともに、角度読み取り位置Ｐｒの角度すなわち測角値をａ_ｒとすると、次式が得られる
Ｐｒ−Ｐ’＝Ｒ’ｔａｎ（ａ_ｒ−Ａ’）（２） At the time of angle measurement, the most probable values P ′, R ′, and A ′ are obtained from the position of the slit image on the CCD line sensor 23 by the above-described regression analysis. Therefore, in the equation (1), when p _i = Pr, P = P ′, R = R ′, A = A ′ and the angle of the angle reading position Pr, that is, the measured angle value is a _r , _{Pr-P '= R'tan (a} r -A' where obtained) (2)

（２）式を変形すると、測角値ａ_ｒが次式によって得られる。
ａ_ｒ＝ｔａｎ^−１｛（Ｐｒ−Ｐ’）／Ｒ’｝＋Ａ’ （３） When the equation (2) is transformed, a measured angle value a _r is obtained by the following equation.
a _r = tan ⁻¹ {(Pr−P ′) / R ′} + A ′ (3)

特開２００７−６４９４９号JP 2007-64949 A 特願２００７−１５８６０７号Japanese Patent Application No. 2007-158607

ここで、エンコーダにおいて、角度読み取り位置として適切な位置Ｐｒ’について考える。 Here, a position Pr ′ suitable as an angle reading position in the encoder is considered.

図５は、目盛盤３が回転軸４に直交して取り付けられているととともに、回転軸４と直交する平面内にＣＣＤラインセンサ２３が位置した状態を、回転軸４及びＣＣＤラインセンサ２３の両方と直交する方向から見た図である。このとき、角度読み取り位置として適切な位置Ｐｒ’は、光源２１を通過して、かつ回転軸４と平行な直線がＣＣＤラインセンサ２３と交わる点である。図５に示すように、光源２１は回転軸４上又はその近傍に配置されるため、角度読み取り位置として適切な位置Ｐｒ’は、目盛盤３と回転軸４の交点と光源２１とを結ぶ直線がＣＣＤラインセンサ２３と交わる点である。 FIG. 5 shows a state in which the scale plate 3 is mounted orthogonally to the rotating shaft 4 and the CCD line sensor 23 is positioned in a plane orthogonal to the rotating shaft 4. It is the figure seen from the direction orthogonal to both. At this time, an appropriate position Pr ′ as an angle reading position is a point where a straight line passing through the light source 21 and parallel to the rotation axis 4 intersects the CCD line sensor 23. As shown in FIG. 5, since the light source 21 is disposed on or near the rotation axis 4, a suitable position Pr ′ as an angle reading position is a straight line connecting the intersection of the dial 3 and the rotation axis 4 and the light source 21. Is the point where it intersects with the CCD line sensor 23.

図６に示したように、目盛盤３が回転軸４に直交して取り付けられていないと、目盛盤３の回転に伴い、ＣＣＤラインセンサ２３と目盛盤３との間の距離が変化する。このような状態のとき、角度読み取り位置Ｐｒが適切な位置Ｐｒ’にないと、目盛盤３上の異なる位置のスリット３２から角度を読んでしまうことになって、誤差ｅを生じる。 As shown in FIG. 6, if the scale plate 3 is not attached perpendicularly to the rotation axis 4, the distance between the CCD line sensor 23 and the scale plate 3 changes as the scale plate 3 rotates. In such a state, if the angle reading position Pr is not at an appropriate position Pr ′, the angle is read from the slits 32 at different positions on the dial 3 and an error e is generated.

誤差ｅが発生する様子について、図６を使用して説明する。目盛盤３上で角度を読み取る位置は、光源２１と角度読み取り位置Ｐｒを結ぶ直線と目盛盤３との交点である。図６に示したように、角度読み取り位置Ｐｒが適な位置Ｐｒ’からずれている場合、目盛盤３の回転に伴いＣＣＤラインセンサ２３と目盛盤３との距離が長くなるにつれて、角度を読み取る目盛盤３上の位置が回転軸４に近づく側に移動する。一方、目盛盤３の回転に伴いＣＣＤラインセンサ２３と目盛盤３との距離が短くなるにつれて、角度を読み取る目盛盤３上の位置が回転軸４から遠ざかる側に移動する。ＣＣＤラインセンサ２３と目盛盤３との距離の変化に依存して発生する目盛盤３上での角度読み取り位置の変動が、すなわち誤差ｅになる。 The manner in which the error e occurs will be described with reference to FIG. The position where the angle is read on the scale plate 3 is an intersection of the scale plate 3 and a straight line connecting the light source 21 and the angle reading position Pr. As shown in FIG. 6, when the angle reading position Pr is deviated from an appropriate position Pr ′, the angle is read as the distance between the CCD line sensor 23 and the scale plate 3 increases as the scale plate 3 rotates. The position on the dial 3 moves to the side approaching the rotation axis 4. On the other hand, as the distance between the CCD line sensor 23 and the scale board 3 becomes shorter as the scale board 3 rotates, the position on the scale board 3 for reading the angle moves to the side away from the rotary shaft 4. The fluctuation of the angle reading position on the scale plate 3 that occurs depending on the change in the distance between the CCD line sensor 23 and the scale plate 3 is an error e.

また、図７に示したように、ＣＣＤラインセンサ２３が回転軸４に直交する平面２２から角度φだけ傾いていると、前記（１）式によって算出した角度読み取り位置Ｐｒが、適切な位置Ｐｒ’からずれてしまうという問題を生じる。これは、ＣＣＤラインセンサ２３の中央部付近から左側に行くほど、ＣＣＤラインセンサ２３と目盛盤３との距離が長くなって、ＣＣＤラインセンサ２３に投影されるスリット像の位置が左側にずれていき、逆に右側に行くほど、ＣＣＤラインセンサ２３と目盛盤３との距離が短くなって、ＣＣＤラインセンサ２３に投影されるスリット像の位置が左側にずれていくことによる。こうして、角度読み取り位置Ｐｒが、適切な位置Ｐｒ’からずれてしまい、かつ、図６に示したように、目盛盤３が回転軸４に直交して取り付けられていないと、目盛盤３の回転に伴いＣＣＤラインセンサ２３と目盛盤３との間の距離が変化して、測角値に誤差が出ることになる。 As shown in FIG. 7, when the CCD line sensor 23 is inclined by an angle φ from the plane 22 orthogonal to the rotation axis 4, the angle reading position Pr calculated by the equation (1) is an appropriate position Pr. This causes the problem of being off. This is because the distance between the CCD line sensor 23 and the scale 3 increases as the distance from the center of the CCD line sensor 23 to the left increases, and the position of the slit image projected on the CCD line sensor 23 shifts to the left. On the contrary, the distance from the CCD line sensor 23 to the scale 3 becomes shorter as the position goes to the right, and the position of the slit image projected on the CCD line sensor 23 is shifted to the left. Thus, if the angle reading position Pr is deviated from the appropriate position Pr ′ and the scale board 3 is not attached perpendicularly to the rotary shaft 4 as shown in FIG. As a result, the distance between the CCD line sensor 23 and the scale plate 3 changes, and an error occurs in the angle measurement value.

本発明は、前記問題に鑑みてなされたものであり、エンコーダにおいて、角度目盛を読み取るラインセンサが目盛盤の回転軸に直交する平面に対して傾いている場合でも、測角値に誤差が生じないようにすることを課題とする。 The present invention has been made in view of the above problems, and in the encoder, even when the line sensor for reading the angle scale is inclined with respect to the plane perpendicular to the rotation axis of the scale board, an error occurs in the angle measurement value. The challenge is to avoid it.

前記課題を解決するため、請求項１に係る発明では、角度目盛と該角度目盛に沿って該角度目盛と同心の同心円パターンとが形成された目盛盤と、前記角度目盛を読み取るラインセンサと、読み取った角度目盛から内挿計算して測角値を得る演算手段とを備えたエンコーダにおいて、前記角度目盛を実際に読み取る角度読み取り位置Ｐｒ”が、前記ラインセンサに沿う座標上で次式によって決定されて記憶されていることを特徴とする。
Ｐｒ”＝ｃ_ｍ−（Ｐ’−ｃ_ｍ）Ｓｃｍ／（Ｓｐ’−Ｓｃｍ） In order to solve the above-mentioned problem, in the invention according to claim 1, a scale plate in which an angular scale and a concentric circular pattern concentric with the angular scale are formed along the angular scale, a line sensor that reads the angular scale, In an encoder including an arithmetic unit that interpolates from the read angle scale and obtains an angle measurement value, an angle reading position Pr ″ that actually reads the angle scale is determined by the following equation on the coordinates along the line sensor: It is characterized by being stored.
Pr ″ = c _m − (P′−c _m ) Scm / (Sp′−Scm)

ただし、前記目盛盤の回転軸に直交する平面と前記ラインセンサのなす角度をφとしたとき、前記ｃ_ｍは前記ラインセンサの受光領域中心線と前記同心円パターンとの２交点の中点の座標、前記Ｐ’は前記目盛盤の中心から前記ラインセンサへ引いた垂線の足の位置を回帰分析から求めた最確値、前記Ｓｃｍは、前記ラインセンサの受光領域中心線と前記同心円パターンとの２交点の中点の座標ｃ_ｍから角度読み取り位置の適切な位置を減じた関数ｆｃｍ（φ）の前記角度φに対する傾き、前記Ｓｐ’は目盛盤の中心から前記ラインセンサへ引いた垂線の足の位置を回帰分析から求めた最確値Ｐ’から角度読み取り位置の適切な位置を減じた関数ｆｐ’（φ）の前記角度φに対する傾きである。 However, when the angle formed by the line sensor and the plane perpendicular to the rotary axis of the dial plate is φ, _cm is the coordinate of the midpoint of the two intersections of the light receiving area center line of the line sensor and the concentric pattern , P ′ is the most probable value obtained by regression analysis of the position of the foot of the perpendicular drawn from the center of the scale plate to the line sensor, and the Scm is 2 of the light receiving area center line of the line sensor and the concentric circle pattern. The slope of the function fcm (φ), which is obtained by subtracting the appropriate position of the angle reading position from the coordinate _cm of the midpoint of the intersection, with respect to the angle φ, Sp ′ is the vertical foot drawn from the center of the dial to the line sensor This is the slope of the function fp ′ (φ) obtained by subtracting the appropriate position of the angle reading position from the most probable value P ′ obtained from the regression analysis with respect to the angle φ.

請求項２に係る発明では、角度目盛及び該角度目盛に沿って該角度目盛と同心の同心円パターンが形成された目盛盤と、前記角度目盛を読み取るラインセンサと、読み取った角度目盛から内挿計算して測角値を得る演算手段とを備えたエンコーダにおいて、前記角度目盛を実際に読み取る角度読み取り位置Ｐｒ”が、次式によって決定されて記憶されていることを特徴とする。
Ｐｒ”＝ｃ_ｍ−（Ｎ−ｃ_ｍ）Ｓｃｍ／（Ｓｐ’−Ｓｃｍ） In the invention according to claim 2, an angle scale and a scale board in which a concentric pattern concentric with the angle scale is formed along the angle scale, a line sensor for reading the angle scale, and an interpolation calculation from the read angle scale Then, in the encoder provided with the calculating means for obtaining the angle measurement value, the angle reading position Pr ″ for actually reading the angle scale is determined and stored by the following equation.
Pr ″ = c _m − (N−c _m ) Scm / (Sp′−Scm)

ただし、前記目盛盤の回転軸に直交する平面と前記ラインセンサのなす角度をφとしたとき、前記ｃ_ｍは前記ラインセンサの受光領域中心線と前記同心円パターンとの２交点の中点の座標、前記Ｎは前記ラインセンサで読み取った前記角度目盛の間隔が最小となる位置を回帰分析から求めた最確値、前記Ｓｃｍは、前記ラインセンサの受光領域中心線と前記同心円パターンとの２交点の中点の座標ｃ_ｍから角度読み取り位置の適切な位置を減じた関数ｆｃｍ（φ）の前記角度φに対する傾き、前記Ｓｐ’は前記ラインセンサで読み取った前記角度目盛の間隔が最小となる位置を回帰分析から求めた最確値Ｎから角度読み取り位置の適切な位置を減じた関数ｆｐ’（φ）の前記角度φに対する傾きである。 However, when the angle formed by the line sensor and the plane perpendicular to the rotary axis of the dial plate is φ, _cm is the coordinate of the midpoint of the two intersections of the light receiving area center line of the line sensor and the concentric pattern , N is the most probable value obtained from regression analysis of the position where the interval of the angle scale read by the line sensor is minimum, and Scm is the two intersections of the light receiving area center line of the line sensor and the concentric circle pattern The slope of the function fcm (φ) obtained by subtracting the appropriate position of the angle reading position from the coordinate _{cm of the} midpoint with respect to the angle φ, and Sp ′ is the position where the interval of the angle scale read by the line sensor is minimized. This is the slope of the function fp ′ (φ) obtained by subtracting the appropriate position of the angle reading position from the most probable value N obtained from the regression analysis with respect to the angle φ.

請求項３に係る発明では、角度目盛が形成された目盛盤と、前記角度目盛を読み取るラインセンサと、読み取った角度目盛から内挿計算して測角値を得る演算手段とを備えたエンコーダにおいて、前記目盛盤の直径に対して対称位置であるとともに前記ラインセンサによって受光可能な位置に一対の点状パターンを前記目盛盤に形成し、前記角度目盛を実際に読み取る角度読み取り位置Ｐｒ”が、前記ラインセンサに沿う座標上で次式によって決定されて記憶されていることを特徴とする。
Ｐｒ”＝ｃ_ｍ’−（Ｐ’−ｃ_ｍ’）Ｓｃｍ／（Ｓｐ’−Ｓｃｍ） In an invention according to claim 3, in an encoder comprising a scale board in which an angle scale is formed, a line sensor that reads the angle scale, and a calculation means that obtains an angle measurement value by interpolating from the read angle scale. In addition, a pair of dot patterns are formed on the scale plate at positions that are symmetrical with respect to the diameter of the scale plate and can be received by the line sensor, and an angle reading position Pr ″ that actually reads the angle scale is: It is determined and stored by the following equation on coordinates along the line sensor.
Pr ″ = c _m ′ − (P′−c _m ′) Scm / (Sp′−Scm)

ただし、前記目盛盤の回転軸に直交する平面と前記ラインセンサのなす角度をφとしたとき、前記ｃ_ｍ’は前記ラインセンサの受光領域中心線と前記同心円パターンとの２交点の中点の座標、前記Ｐ’は前記目盛盤の中心から前記ラインセンサへ引いた垂線の足の位置を回帰分析から求めた最確値、前記Ｓｃｍは、前記一対の点状パターンの中点の座標ｃ_ｍ’から角度読み取り位置の適切な位置を減じた関数ｆｃｍ（φ）の前記角度φに対する傾き、前記Ｓｐ’は目盛盤の中心から前記ラインセンサへ引いた垂線の足の位置を回帰分析から求めた最確値Ｐ’から角度読み取り位置の適切な位置を減じた関数ｆｐ’（φ）の前記角度φに対する傾きである。 However, when the angle formed between the plane perpendicular to the rotation axis of the scale plate and the line sensor is φ, the c _m ′ is the midpoint of the two intersections between the center line of the light receiving area of the line sensor and the concentric pattern. The coordinate, P ′ is the most probable value obtained by regression analysis of the position of the foot of the perpendicular drawn from the center of the scale plate to the line sensor, and the Scm is the coordinate c _m ′ of the midpoint of the pair of point patterns The slope of the function fcm (φ) obtained by subtracting the appropriate position of the angle reading position from the angle φ, and Sp ′ is the position of the vertical foot drawn from the center of the scale plate to the line sensor by regression analysis. This is the slope of the function fp ′ (φ) obtained by subtracting the appropriate position of the angle reading position from the accuracy value P ′ with respect to the angle φ.

請求項４に係る発明では、角度目盛が形成された目盛盤と、前記角度目盛を読み取るラインセンサと、読み取った角度目盛から内挿計算して測角値を得る演算手段とを備えたエンコーダにおいて、前記目盛盤の直径に対して対称位置であるとともに前記ラインセンサによって受光可能な位置に一対の点状パターンを前記目盛盤に形成し、前記角度目盛を実際に読み取る角度読み取り位置Ｐｒ”が、次式によって決定されて記憶されていることを特徴とする。
Ｐｒ”＝ｃ_ｍ’−（Ｎ−ｃ_ｍ’）Ｓｃｍ／（Ｓｐ’−Ｓｃｍ） In an invention according to claim 4, in an encoder comprising a scale board in which an angle scale is formed, a line sensor that reads the angle scale, and a calculation means that obtains an angle measurement value by interpolating from the read angle scale. In addition, a pair of dot patterns are formed on the scale plate at positions that are symmetrical with respect to the diameter of the scale plate and can be received by the line sensor, and an angle reading position Pr ″ that actually reads the angle scale is: It is determined by the following formula and stored.
Pr ″ = c _m ′ − (N−c _m ′) Scm / (Sp′−Scm)

ただし、前記目盛盤の回転軸に直交する平面と前記ラインセンサのなす角度をφとしたとき、前記ｃ_ｍ’は前記ラインセンサの受光領域中心線と前記同心円パターンとの２交点の中点の座標、前記Ｎは前記ラインセンサで読み取った前記角度目盛の間隔が最小となる位置を回帰分析から求めた最確値、前記Ｓｃｍは、前記ラインセンサで読んだ前記一対の点状パターンの中点の座標ｃ_ｍ’から角度読み取り位置の適切な位置を減じた関数ｆｃｍ（φ）の前記角度φに対する傾き、前記Ｓｐ’は前記ラインセンサで読み取った前記角度目盛の間隔が最小となる位置を回帰分析から求めた最確値Ｎから角度読み取り位置の適切な位置を減じた関数ｆｐ’（φ）の前記角度φに対する傾きである。 However, when the angle formed between the plane perpendicular to the rotation axis of the scale plate and the line sensor is φ, the c _m ′ is the midpoint of the two intersections between the center line of the light receiving area of the line sensor and the concentric pattern. The coordinate, N is the most probable value obtained from regression analysis of the position where the interval of the angle scale read by the line sensor is minimum, and the Scm is the midpoint of the pair of point patterns read by the line sensor An inclination of the function fcm (φ) obtained by subtracting an appropriate position of the angle reading position from the coordinate _cm ′ with respect to the angle φ, and Sp ′ is a regression analysis of the position where the interval of the angle scale read by the line sensor is minimized. Is the slope of the function fp ′ (φ) obtained by subtracting the appropriate position of the angle reading position from the most probable value N obtained from

請求項５に係る発明では、角度目盛が形成された目盛盤と、前記角度目盛を読み取るラインセンサと、読み取った角度目盛から内挿計算して測角値を得る演算手段とを備えたエンコーダにおいて、前記角度目盛を実際に読み取る角度読み取り位置Ｐｒ”が、前記ラインセンサに沿う座標上で次式によって決定されて記憶されていることを特徴とする。
Ｐｒ”＝ｃ_ｍ”−（Ｐ’−ｃ_ｍ”）Ｓｃｍ／（Ｓｐ’−Ｓｃｍ） In the invention which concerns on Claim 5, in the encoder provided with the scale board in which the angle scale was formed, the line sensor which reads the said angle scale, and the calculating means which interpolates from the read angle scale, and obtains a measured value The angle reading position Pr ″ for actually reading the angle scale is determined and stored by the following equation on the coordinates along the line sensor.
Pr ″ = c _m ″ − (P′−c _m ″) Scm / (Sp′−Scm)

ただし、前記目盛盤の回転軸に直交する平面と前記ラインセンサのなす角度をφとしたとき、前記ｃ_ｍ”は前記ラインセンサが受光した両端の角度目盛の位置の中点の座標、前記Ｐ’は前記目盛盤の中心から前記ラインセンサへ引いた垂線の足の位置を回帰分析から求めた最確値、前記Ｓｃｍは、前記ラインセンサが受光した両端の角度目盛の位置の中点の座標ｃ_ｍ”から角度読み取り位置の適切な位置を減じた関数ｆｃｍ（φ）の前記角度φに対する傾き、前記Ｓｐ’は目盛盤の中心から前記ラインセンサへ引いた垂線の足の位置を回帰分析から求めた最確値Ｐ’から角度読み取り位置の適切な位置を減じた関数ｆｐ’（φ）の前記角度φに対する傾きである。 However, when the angle formed between the plane perpendicular to the rotation axis of the scale plate and the line sensor is φ, c _m ″ is the coordinate of the midpoint of the position of the angle scale at both ends received by the line sensor, the P 'Is the most probable value obtained from regression analysis of the position of the foot of the perpendicular drawn from the center of the scale plate to the line sensor, and Scm is the coordinate c of the midpoint of the position of the angle scale received by the line sensor. _The inclination of the function fcm (φ) obtained by subtracting the appropriate position of the angle reading position from _m ″ with respect to the angle φ, and Sp ′ is the position of the vertical leg drawn from the center of the scale plate to the line sensor by regression analysis Further, the slope of the function fp ′ (φ) obtained by subtracting the appropriate position of the angle reading position from the most probable value P ′ with respect to the angle φ.

請求項６に係る発明では、角度目盛が形成された目盛盤と、前記角度目盛を読み取るラインセンサと、読み取った角度目盛から内挿計算して測角値を得る演算手段とを備えたエンコーダにおいて、前記角度目盛を実際に読み取る角度読み取り位置Ｐｒ”が、次式によって決定されて記憶されていることを特徴とする。
Ｐｒ”＝ｃ_ｍ”−（Ｎ−ｃ_ｍ”）Ｓｃｍ／（Ｓｐ’−Ｓｃｍ） In the invention which concerns on Claim 6, in the encoder provided with the scale board in which the angle scale was formed, the line sensor which reads the said angle scale, and the calculating means which interpolates from the read angle scale, and obtains a measured value The angle reading position Pr ″ for actually reading the angle scale is determined by the following equation and stored.
Pr ″ = c _m ″ − (N−c _m ″) Scm / (Sp′−Scm)

ただし、前記目盛盤の回転軸に直交する平面と前記ラインセンサのなす角度をφとしたとき、前記ｃ_ｍ”は前記ラインセンサが受光した両端の角度目盛の位置の中点の座標、前記Ｎは前記ラインセンサで読み取った前記角度目盛の間隔が最小となる位置を回帰分析から求めた最確値、前記Ｓｃｍは、前記ラインセンサが受光した両端の角度目盛の位置の中点の座標ｃ_ｍ”から角度読み取り位置の適切な位置を減じた関数ｆｃｍ（φ）の前記角度φに対する傾き、前記Ｓｐ’は前記ラインセンサで読み取った前記角度目盛の間隔が最小となる位置を回帰分析から求めた最確値Ｎから角度読み取り位置の適切な位置を減じた関数ｆｐ’（φ）の前記角度φに対する傾きである。 However, when the angle between the plane perpendicular to the rotary axis of the scale plate and the line sensor is φ, c _m ″ is the coordinates of the midpoint of the position of the angle scale received by the line sensor, and the N Is the most probable value obtained by regression analysis of the position where the interval of the angle scales read by the line sensor is minimum, and Scm is the coordinate c _m ″ of the midpoint positions of the angle scales received by the line sensor. The slope of the function fcm (φ) obtained by subtracting the appropriate position of the angle reading position from the angle φ, and Sp ′ is the maximum position obtained from the regression analysis by determining the position at which the interval of the angle scale read by the line sensor is minimum. This is the slope of the function fp ′ (φ) obtained by subtracting the appropriate position of the angle reading position from the accuracy value N with respect to the angle φ.

請求項７に係る発明では、請求項１、２、３、４、５又は６に係る発明において、前記Ｓｃｍ／（Ｓｐ’−Ｓｃｍ）の値を、前記回転軸から前記ラインセンサまでの距離に応じて補正したことを特徴とする。 In the invention according to claim 7, in the invention according to claim 1, 2, 3, 4, 5 or 6, the value of Scm / (Sp′−Scm) is set to the distance from the rotation axis to the line sensor. The correction is made accordingly.

請求項１〜６に係る各発明によれば、角度目盛を実際に読み取る角度読み取り位置Ｐｒ”が、目盛盤の回転軸に直交する平面とラインセンサのなす角度φに応じて補正しているため、ラインセンサが目盛盤の回転軸に直交する平面に対して傾いている場合でも、測角値に誤差が生じないようになる。 According to each of the first to sixth aspects of the present invention, the angle reading position Pr ″ for actually reading the angle scale is corrected according to the angle φ formed by the plane perpendicular to the rotation axis of the scale plate and the line sensor. Even when the line sensor is tilted with respect to a plane orthogonal to the rotation axis of the scale plate, no error occurs in the angle measurement value.

請求項７に係る発明によれば、さらに、角度目盛を実際に読み取る角度読み取り位置Ｐｒ”が、目盛盤の回転軸から前記ラインセンサまでの距離に応じても補正されているため、いっそう測角値に誤差が生じないようになる。 According to the seventh aspect of the present invention, the angle reading position Pr ″ for actually reading the angle scale is also corrected according to the distance from the rotary axis of the scale plate to the line sensor, so that the angle measurement is further performed. There will be no error in the value.

従来のエンコーダの構成を説明する図である。It is a figure explaining the structure of the conventional encoder. 前記エンコーダの目盛盤の平面図である。It is a top view of the scale board of the encoder. 前記エンコーダにおいて、角度読み取り位置を決定する方法を説明する図である。It is a figure explaining the method to determine an angle reading position in the encoder. 測角時における内挿計算に用いるモデルを説明する図である。It is a figure explaining the model used for the interpolation calculation at the time of angle measurement. エンコーダにおいて、適切な角度読み取り位置を説明する図である。It is a figure explaining an appropriate angle reading position in an encoder. 目盛盤と該目盛盤の回転軸が直交していないとき、測角値に誤差を生じる理由を説明する図である。It is a figure explaining the reason which produces an error in a measured angle value when the scale board and the rotation axis of the scale board are not orthogonal. ＣＣＤラインセンサが目盛盤の回転軸に直交する平面に対して角度φだけ傾斜しているとき、（１）式によって算出した角度読み取り位置が適切な位置からずれてしまう理由を説明する図である。When the CCD line sensor is inclined by an angle φ with respect to a plane perpendicular to the rotation axis of the scale plate, it is a diagram for explaining the reason why the angle reading position calculated by the equation (1) is shifted from an appropriate position. . エンコーダにおいて、ＣＣＤラインセンサ上で角度読み取り位置として記憶する位置を算出する方法を説明する図である。It is a figure explaining the method of calculating the position memorize | stored as an angle reading position on a CCD line sensor in an encoder. 本発明の第１の実施例に係るエンコーダを説明する図である。It is a figure explaining the encoder which concerns on 1st Example of this invention. 本発明の第２の実施例に係るエンコーダを説明する図である。It is a figure explaining the encoder which concerns on 2nd Example of this invention. 本発明の第３の実施例に係るエンコーダを説明する図である。It is a figure explaining the encoder which concerns on the 3rd Example of this invention. 本発明の第５の実施例に係るエンコーダを説明する図である。It is a figure explaining the encoder which concerns on the 5th Example of this invention. 本発明の第７の実施例に係るエンコーダを説明する図である。It is a figure explaining the encoder which concerns on the 7th Example of this invention. ＣＣＤラインセンサの出力を示す図である。It is a figure which shows the output of a CCD line sensor.

まず、図１〜図９に基づいて、本発明の第１の実施例について説明する。本実施例のエンコーダは、図１〜図３に示した従来のものと同じく、目盛盤３にスリット３２が設けられ、さらに同心円パターン３３が設けられている。同心円パターン３３は、図３に示したように、その像がＣＣＤラインセンサ２３と２個所で交わり、その２個所の座標ｃ_１、ｃ_２をＣＣＤラインセンサ２３で読んで、その中点の座標ｃ_ｍを求めるためのものである。また、スリット３２は、ＣＣＤラインセンサ２３で読んで、図４で説明した従来のものと同様に内挿計算により測角に用いるものである。 First, a first embodiment of the present invention will be described with reference to FIGS. The encoder of the present embodiment is provided with slits 32 on the dial plate 3 and further with concentric patterns 33 as in the conventional encoder shown in FIGS. As shown in FIG. 3, the concentric pattern 33 intersects the CCD line sensor 23 at two locations, and the coordinates c ₁ and c ₂ at the two locations are read by the CCD line sensor 23, and the coordinates of the midpoint thereof are obtained. It is for calculating _cm . The slit 32 is read by the CCD line sensor 23 and used for angle measurement by interpolation calculation as in the conventional case described with reference to FIG.

ＣＣＤラインセンサ２３は、目盛盤３の回転軸４に直交する平面内に配置されるべきものである。しかし、図７に示したように、ＣＣＤラインセンサ２３が目盛盤３の回転軸４に直交する平面２２から角度φだけ傾いた状態を考える。角度φを少しづつ変えながら、従来と同様に前記（１）式を用いた回帰分析により、目盛盤３の中心ＯからＣＣＤラインセンサ２３へ引いた垂線の足の位置Ｐの最確値Ｐ’（従来の角度読み取り位置Ｐｒの設定値）を求め、この最確値Ｐ’から角度読み取り位置の適切な位置Ｐｒ’（図５参照）を減じた値ｆｐ’（φ）＝Ｐ’−Ｐｒ’を計算する。このｆｐ’（φ）をφの関数として、関数ｆｐ’（φ）のφによる変化を図８に示す。 The CCD line sensor 23 should be arranged in a plane perpendicular to the rotation axis 4 of the scale plate 3. However, as shown in FIG. 7, a state is considered in which the CCD line sensor 23 is inclined by an angle φ from the plane 22 orthogonal to the rotation axis 4 of the dial 3. The most probable value P ′ of the position P of the perpendicular foot drawn from the center O of the scale plate 3 to the CCD line sensor 23 by regression analysis using the above equation (1) while changing the angle φ little by little. A conventional setting value of the angle reading position Pr) is obtained, and a value fp ′ (φ) = P′−Pr ′ obtained by subtracting an appropriate position Pr ′ (see FIG. 5) of the angle reading position from the most probable value P ′ is calculated. To do. FIG. 8 shows a change of the function fp ′ (φ) due to φ, where fp ′ (φ) is a function of φ.

同様に角度φを少しづつ変えながら、同心円パターン３３の像とＣＣＤラインセンサ２３との２個所の交点Ａ、Ｂの中点ｃ_ｍから角度読み取り位置の適切な位置Ｐｒ’を減じた値ｆｃｍ（φ）＝ｃ_ｍ−Ｐｒ’も計算する。このｆｃｍ（φ）をφの関数として、関数ｆｐ’（φ）のφによる変化も図８に示す。図８を作成するに際しては、ｆｐ’（φ）及びｆｃｍ（φ）を幾何学的に計算から求めてもよいし、実験から求めてもよい。図８からは、ｆｐ’（φ）及びｆｃｍ（φ）は、ともに角度φの変化に対して直線的に変化していることが分かる。 Similarly, while changing the angle φ little by little, a value fcm () obtained by subtracting the appropriate position Pr ′ of the angle reading position from the midpoint _cm of the intersections A and B of the image of the concentric pattern 33 and the CCD line sensor 23. φ) = c _m −Pr ′ is also calculated. FIG. 8 also shows changes in the function fp ′ (φ) due to φ, where fcm (φ) is a function of φ. In creating FIG. 8, fp ′ (φ) and fcm (φ) may be obtained geometrically by calculation or by experiment. FIG. 8 shows that both fp ′ (φ) and fcm (φ) change linearly with respect to the change in angle φ.

そこで、角度φが任意の値φ’のときのｆｐ’（φ’）及びｆｃｍ（φ’）を求め、次の（４）式を計算して、製品の工場からの出荷時に測量機に記憶させる。
ｆｃｍ（φ’）／｛ｆｐ’（φ’）−ｆｃｍ（φ’）｝（４） Therefore, fp ′ (φ ′) and fcm (φ ′) when the angle φ is an arbitrary value φ ′ are obtained, and the following equation (4) is calculated and stored in the surveying instrument when the product is shipped from the factory. Let
fcm (φ ′) / {fp ′ (φ ′) − fcm (φ ′)} (4)

ただし、φ’は、ＣＣＤラインセンサ２３の取付状態とは無関係に設定できる任意の値である。つまり、工場で製造した製品の中から任意の１個を取り出したときに、その取り出した製品のエンコーダにおける回転軸４に直交する平面２２とＣＣＤラインセンサ２３との実際の傾き角度φと（４）式で代入するφ’とは必ずしも一致する必要はない。したがって、（４）式を計算して測量機に記憶させる装置は、製造する全てのエンコーダに対して同じ装置にすることができる。 However, φ ′ is an arbitrary value that can be set regardless of the mounting state of the CCD line sensor 23. That is, when an arbitrary one is taken out from the product manufactured at the factory, the actual inclination angle φ between the plane 22 perpendicular to the rotation axis 4 and the CCD line sensor 23 in the encoder of the taken-out product and (4 It is not always necessary to agree with φ ′ to be substituted in the formula. Therefore, the apparatus for calculating the equation (4) and storing it in the surveying instrument can be the same apparatus for all the encoders to be manufactured.

さらに、図９に示したように、製品の工場からの出荷時には、製品毎に目盛盤３の中心ＯからＣＣＤラインセンサ２３へ引いた垂線の足の位置Ｐの最確値Ｐ’と、同心円パターン３３の像とＣＣＤラインセンサ２３との２個所の交点Ａ、Ｂの中点ｃ_ｍを求めて、次の（５）式によって、角度読み取り位置として記憶する位置Ｐｒ”を計算して、測量機に記憶させる。このとき、既に記憶している（４）式の値が利用される。
Ｐｒ”＝ｃ_ｍ−（Ｐ’−ｃ_ｍ）ｆｃｍ（φ’）／｛ｆｐ’（φ’）−ｆｃｍ（φ’）｝（５） Further, as shown in FIG. 9, when the product is shipped from the factory, the most probable value P ′ of the position P of the perpendicular foot drawn from the center O of the scale plate 3 to the CCD line sensor 23 for each product and the concentric pattern The middle point _cm of the intersections A and B of the two images 33 and the CCD line sensor 23 is obtained, and the position Pr ″ stored as the angle reading position is calculated by the following equation (5). At this time, the value of the expression (4) that is already stored is used.
Pr ″ = c _m − (P′−c _m ) fcm (φ ′) / {fp ′ (φ ′) − fcm (φ ′)} (5)

角度読み取り位置として記憶する置Ｐｒ”は、次のようにして求めることもできる。図８におけるｆｐ’（φ）及びｆｃｍ（φ）のそれぞれの傾きＳｐ’及びＳｃｍは、次のように表される。
Ｓｐ’＝｛ｆｐ’（φ’）−ｆｐ’（−φ’）｝／｛φ’−（−φ’）｝
＝｛ｆｐ’（φ’）−ｆｐ’（−φ’）｝／（２φ’）（６）
Ｓｃｍ＝｛ｆｃｍ（φ’）−ｆｃｍ（−φ’）｝／｛φ’−（−φ’）｝
＝｛ｆｃｍ（φ’）−ｆｃｍ（−φ’）｝／（２φ’）（７）
（６）式及び（７）式から、次の（８）式を計算して、これを測量機に記憶させておく。
Ｓｃｍ／（Ｓｐ’−Ｓｃｍ）（８） The position Pr ″ stored as the angle reading position can also be obtained as follows. The respective slopes Sp ′ and Scm of fp ′ (φ) and fcm (φ) in FIG. 8 are expressed as follows. The
Sp ′ = {fp ′ (φ ′) − fp ′ (− φ ′)} / {φ ′ − (− φ ′)}
= {Fp ′ (φ ′) − fp ′ (− φ ′)} / (2φ ′) (6)
Scm = {fcm (φ ′) − fcm (−φ ′)} / {φ ′ − (− φ ′)}
= {Fcm (φ ′) − fcm (−φ ′)} / (2φ ′) (7)
From the equations (6) and (7), the following equation (8) is calculated and stored in the surveying instrument.
Scm / (Sp'-Scm) (8)

ただし、前述したように、φ’は、ＣＣＤラインセンサ２３の取付状態とは無関係に設定できる任意の値である。したがって、（６）式及び（７）式を計算し、さらに（８）式を計算して測量機に記憶させる装置は、製造する全てのエンコーダに対して同じ装置にすることができる。 However, as described above, φ ′ is an arbitrary value that can be set regardless of the mounting state of the CCD line sensor 23. Therefore, the apparatus which calculates (6) Formula and (7) Formula, and also calculates (8) Formula and memorize | stores it in a surveying instrument can be made the same apparatus with respect to all the encoders manufactured.

そして、角度読み取り位置として記憶する位置Ｐｒ”を次の（９）式で算出して、測量機に記憶させてもよい。このとき、（８）式の値が利用される。
Ｐｒ”＝ｃ_ｍ−（Ｐ’−ｃ_ｍ）Ｓｃｍ／（Ｓｐ’−Ｓｃｍ）（９） Then, the position Pr ″ stored as the angle reading position may be calculated by the following equation (9) and stored in the surveying instrument. At this time, the value of the equation (8) is used.
Pr ″ = c _m − (P′−c _m ) Scm / (Sp′−Scm) (9)

本実施例によれば、この角度読み取り位置Ｐｒ”を用いることによって、ＣＣＤラインセンサ２３が目盛盤３の回転軸４に直交する平面に対して傾いている場合でも、測角値に誤差が生じなくなる。なお、図５から分かるように、Ｐ’とｃ_ｍとが一致するときは、ＣＣＤラインセンサ２３が回転軸４に直交する平面上に位置しているから、Ｐ’とｃ_ｍとが一致するようにＣＣＤラインセンサ２３の配置を調整すれば、従来どおりの角度読み取り位置値Ｐｒを用いてもよい。 According to the present embodiment, by using the angle reading position Pr ″, an error occurs in the measured angle value even when the CCD line sensor 23 is inclined with respect to the plane perpendicular to the rotation axis 4 of the scale plate 3. As can be seen from Fig. 5, when P 'and _cm match, the CCD line sensor 23 is located on a plane orthogonal to the rotation axis 4, so P' and _cm are If the arrangement of the CCD line sensor 23 is adjusted so as to match, the conventional angle reading position value Pr may be used.

次に、第２の実施例について説明する。本実施例では、図１０に示したように、同心円パターン３３の像がＣＣＤラインセンサ２３と交わる２点Ａ、Ｂの中点Ｍの座標ｃ_ｍを求めることは、前記第１の実施例と同じである。ただし、本実施例では、目盛盤３の中心ＯからＣＣＤラインセンサ２３へ引いた垂線の足の位置Ｐを求める代わりに、ＣＣＤラインセンサ２３上でスリット３２像の間隔が最小になる位置を求める。通常、ＣＣＤラインセンサ２３には数十本のスリット３２像が検出される。そこで、スリット３２の間隔とＣＣＤラインセンサ２３に沿う座標との間で、両者の関係を示す二次曲線を回帰分析によって求め、その二次曲線の傾きが零になる位置をスリット３２像の間隔が最小となる位置の最確値Ｎと決める。このＮを前記第１の実施例で説明した垂線の足の位置Ｐの最確値Ｐ’の代わりに用いて、前記第１の実施例と同様な処理をすることによって、角度読み取り位置の適切な値Ｐｒ”を算出する。これ以外は、前記第１の実施例と同じである。 Next, a second embodiment will be described. In this embodiment, as shown in FIG. 10, obtaining the coordinates _cm of the midpoint M between the two points A and B where the image of the concentric pattern 33 intersects the CCD line sensor 23 is the same as in the first embodiment. The same. However, in this embodiment, instead of obtaining the position P of the perpendicular foot drawn from the center O of the scale plate 3 to the CCD line sensor 23, the position on the CCD line sensor 23 where the interval between the slits 32 images is minimized is obtained. . Usually, the CCD line sensor 23 detects several tens of slit 32 images. Therefore, a quadratic curve indicating the relationship between the interval between the slits 32 and the coordinates along the CCD line sensor 23 is obtained by regression analysis, and the position at which the slope of the quadratic curve becomes zero is determined as the interval between the slit 32 images. Is determined to be the most probable value N of the position where is the minimum. By using this N instead of the most probable value P ′ of the position P of the perpendicular foot described in the first embodiment, the same processing as in the first embodiment is performed, so that an appropriate angle reading position can be obtained. The value Pr ″ is calculated. The rest is the same as in the first embodiment.

次に、第３の実施例について説明する。本実施例では、図１１に示したように、同心円パターン３３の代わりに、目盛盤３の直径に対して互いに対称位置であるとともに、ＣＣＤラインセンサ２３によって受光可能な位置に配置された２つの点状パターン３５を設ける。２つの点状パターン３５をＣＣＤラインセンサ２３で捉えて、その座標ｃ_１、ｃ_２を読み、その中点Ｍの座標ｃ_ｍ’を求める。そして、前記ｃ_ｍ’を前記第１の実施例で説明したｃ_ｍの代わりに用い、前記第１の実施例と同様な処理をすることによって、角度読み取り位置の適切な値Ｐｒ”を算出する。これ以外は、前記第１の実施例と同じである。 Next, a third embodiment will be described. In the present embodiment, as shown in FIG. 11, instead of the concentric circle pattern 33, two positions that are symmetrical with respect to the diameter of the scale plate 3 and that can be received by the CCD line sensor 23 are arranged. A dot pattern 35 is provided. The two point-like patterns 35 are captured by the CCD line sensor 23, the coordinates c ₁ and c ₂ are read, and the coordinates c _m ′ of the middle point M are obtained. Then, the use of a c _{m 'instead} of c _m that described in the first embodiment, by the same processing as the first embodiment, to calculate the appropriate value Pr "angular reading position Other than this, the second embodiment is the same as the first embodiment.

次に、第４の実施例について説明する。本実施例では、前記第３実施例と同様に、目盛盤３に２つの点状パターン３５を設け、この点状パターン３５の像をＣＣＤラインセンサ２３で捉えて、その座標ｃ_１、ｃ_２を読み、その中点の座標ｃ_ｍ’を求める。また、前記第２の実施例と同様に、ＣＣＤラインセンサ２３上でスリット３２の像の間隔が最小になる位置の最確値Ｎを求める。このｃ_ｍ’とＮを前記第１の実施例で説明したｃ_ｍとＰ’の代わりに用いて、同様な処理をすることによって、角度読み取り位置の適切な値Ｐｒ”を算出する。これ以外は、前記第１の実施例と同じである。 Next, a fourth embodiment will be described. In the present embodiment, as in the third embodiment, two dot patterns 35 are provided on the scale plate 3, and an image of the dot patterns 35 is captured by the CCD line sensor 23, and the coordinates c ₁ , c ₂ thereof. And the coordinates c _m ′ of the midpoint are obtained. Further, as in the second embodiment, the most probable value N of the position where the image interval of the slit 32 is minimized on the CCD line sensor 23 is obtained. Using this _cm ′ and N instead of _cm and P ′ described in the first embodiment, an appropriate value Pr ″ of the angle reading position is calculated by performing the same process. Is the same as in the first embodiment.

次に第５の実施例について説明する。本実施例では、図１２に示したように、目盛盤１には、同心円も点状パターンも設けられていない。そこで、出荷前の検査時にＣＣＤラインセンサ２３で捉えたスリット３２像に関して、両端のスリット３２とＣＣＤラインセンサ２３との交点Ａ、Ｂの座標ｃ_１、ｃ_２を読み、両者の中点の座標ｃ_ｍ”を求める。このｃ_ｍ”を前記第１の実施例で説明したｃ_ｍの代わりに用いて、同様な処理をすることによって、角度読み取り位置の適切な値Ｐｒ”を算出する。これ以外は、前記第１の実施例と同じである。 Next, a fifth embodiment will be described. In the present embodiment, as shown in FIG. 12, the scale plate 1 is not provided with a concentric circle or a dot pattern. Therefore, with respect to the slit 32 image captured by the CCD line sensor 23 at the time of inspection before shipment, the coordinates c ₁ and c ₂ of the intersections A and B between the slits 32 on both ends and the CCD line sensor 23 are read, and the coordinates of the midpoint of both are read. C _m ″ is obtained. The c _m ″ is used in place of _cm described in the first embodiment, and the same processing is performed to calculate an appropriate value Pr ″ for the angle reading position. Other than the above, the second embodiment is the same as the first embodiment.

次に、第６の実施例について説明する。本実施例では、前記第５実施例と同様に、ＣＣＤラインセンサ２３で捉えたスリット３２の両端のスリット３２とＣＣＤラインセンサ２３との交点Ａ、Ｂの座標ｃ_１、ｃ_２を読み、両者の中点の座標ｃ_ｍ”を求める。また、前記第２の実施例と同様に、ＣＣＤラインセンサ２３上でスリット３２の像の間隔が最小になる位置の最確値Ｎを求める。このｃ_ｍ”とＮを前記第１の実施例で説明したｃ_ｍとＰ’の代わりに用いて、同様な処理をすることによって、角度読み取り位置の適切な値Ｐｒ”を算出する。これ以外は、前記第１の実施例と同じである。 Next, a sixth embodiment will be described. In this embodiment, as in the fifth embodiment, the coordinates c ₁ and c ₂ of the intersections A and B between the slits 32 at both ends of the slit 32 captured by the CCD line sensor 23 and the CCD line sensor 23 are read. determination of the coordinates c _m midpoint _". also, as with the second embodiment, obtaining the most probable value N position interval of the image of the slit 32 is minimized on the CCD line sensor 23. the c _m "And N are used in place of _cm and P 'described in the first embodiment, and the same processing is performed to calculate an appropriate value Pr" of the angle reading position. The same as in the first embodiment.

次に、第７の実施例について説明する。前記第１の実施例では、（９）式から角度読み取り位置として記憶する位置Ｐｒ”が算出されるが、図１３に示したように、目盛盤３の中心ＯとＣＣＤラインセンサ２３との間の距離Ｄ、すなわち回転軸４とＣＣＤラインセンサ２３との距離が変化すると、（８）式の値が変化し、Ｐｒ”も変化する。そこで、本実施例では、回転軸４とＣＣＤラインセンサ２３間の距離Ｄに応じて、Ｐｒ”を変えるようにする。 Next, a seventh embodiment will be described. In the first embodiment, the position Pr ″ stored as the angle reading position is calculated from the equation (9). However, as shown in FIG. 13, the distance between the center O of the dial 3 and the CCD line sensor 23 is calculated. , That is, the distance between the rotary shaft 4 and the CCD line sensor 23 changes, the value of equation (8) changes, and Pr ″ also changes. Therefore, in this embodiment, Pr ″ is changed according to the distance D between the rotating shaft 4 and the CCD line sensor 23.

これには、図１４に示したように、ＣＣＤラインセンサ２３で捉えたスリット３２像から両端のスリット３２間の角度θを算出する。これで、スリット３２の外端に接する円の半径をＬとすると（図１２参照）、目盛盤３の中心ＯとＣＣＤラインセンサ２３間の距離Ｄは、次式から算出される。
Ｄ＝ＬＣｏｓ（θ／２）（１０） For this purpose, as shown in FIG. 14, the angle θ between the slits 32 at both ends is calculated from the slit 32 image captured by the CCD line sensor 23. When the radius of the circle in contact with the outer end of the slit 32 is L (see FIG. 12), the distance D between the center O of the scale plate 3 and the CCD line sensor 23 is calculated from the following equation.
D = LCos (θ / 2) (10)

出荷前の検査で、目盛盤３の中心ＯとＣＣＤラインセンサ２３間の距離Ｄ’が求まると、このＤ’の値から図１３を用いて（８）式で定義されるＳｃｍ／（Ｓｐ’−Ｓｃｍ）の値を求め、この値と（９）式を用いて、回転軸４とＣＣＤラインセンサ２３間の距離Ｄ’による補正を行った角度読み取り位置として記憶する位置Ｐｒ”を算出して、測量機に記憶させておく。この補正を行った角度読み取り位置Ｐｒ”を用いれば、いっそう測角値の誤差を小さくできる。もちろん、第２〜第６の実施例に関しても、目盛盤３の中心ＯとＣＣＤラインセンサ２３間の距離Ｄに応じて同様にＳｃｍ／（Ｓｐ’−Ｓｃｍ）の値を補正してもよい。 When the distance D ′ between the center O of the scale plate 3 and the CCD line sensor 23 is obtained by inspection before shipment, Scm / (Sp ′ defined by the equation (8) using FIG. 13 from the value of D ′. -Scm) is obtained, and using this value and equation (9), the position Pr "stored as the angle reading position corrected by the distance D 'between the rotating shaft 4 and the CCD line sensor 23 is calculated. If the corrected angle reading position Pr ″ is used, the error of the angle measurement value can be further reduced. Of course, also in the second to sixth embodiments, the value of Scm / (Sp′−Scm) may be similarly corrected according to the distance D between the center O of the scale plate 3 and the CCD line sensor 23.

１エンコーダ
３目盛盤
４回転軸
５ＣＰＵ（演算手段）
２３ＣＣＤラインセンサ（ラインセンサ）
３２スリット（角度目盛）
３３同心円パターン
３５点状パターン 1 Encoder 3 Scale plate 4 Rotating shaft 5 CPU (Calculation means)
23 CCD line sensor (line sensor)
32 Slit (Angle scale)
33 Concentric pattern 35 Dot pattern

Claims

A scale plate in which an angle scale and a concentric circular pattern concentric with the angle scale are formed along the angle scale, a line sensor that reads the angle scale, and interpolated from the read angle scale to obtain an angle measurement value In an encoder comprising a calculation means,
An encoder characterized in that an angle reading position Pr ″ for actually reading the angle scale is determined and stored by the following equation on coordinates along the line sensor.
Pr ″ = c _m − (P′−c _m ) Scm / (Sp′−Scm)
However, when the angle formed by the line sensor and the plane perpendicular to the rotary axis of the dial plate is φ, _cm is the coordinate of the midpoint of the two intersections of the light receiving area center line of the line sensor and the concentric pattern , P ′ is the most probable value obtained by regression analysis of the position of the foot of the perpendicular drawn from the center of the scale plate to the line sensor, and the Scm is 2 of the light receiving area center line of the line sensor and the concentric circle pattern. The slope of the function fcm (φ), which is obtained by subtracting the appropriate position of the angle reading position from the coordinate _cm of the midpoint of the intersection, with respect to the angle φ, Sp ′ is the vertical foot drawn from the center of the dial to the line sensor This is the slope of the function fp ′ (φ) obtained by subtracting the appropriate position of the angle reading position from the most probable value P ′ obtained from the regression analysis with respect to the angle φ.

An angle scale and a scale board in which a concentric circular pattern concentric with the angle scale is formed along the angle scale, a line sensor for reading the angle scale, and an operation for obtaining an angle measurement value by interpolating from the read angle scale And an encoder comprising:
An encoder characterized in that an angle reading position Pr ″ for actually reading the angle scale is determined and stored by the following equation.
Pr ″ = c _m − (N−c _m ) Scm / (Sp′−Scm)
However, when the angle formed between the plane perpendicular to the rotation axis of the scale plate and the line sensor is φ, _cm is the midpoint of the two intersections between the center line of the light receiving area of the line sensor and the concentric pattern. Coordinates, N is the most probable value obtained by regression analysis of the position where the interval of the angle scale read by the line sensor is minimum, and Scm is the two intersections of the light receiving area center line of the line sensor and the concentric pattern The slope of the function fcm (φ) obtained by subtracting the appropriate angle reading position from the coordinates _cm of the center point with respect to the angle φ, and Sp ′ is the position where the interval of the angle scale read by the line sensor is minimized. Is the slope of the function fp ′ (φ) obtained by subtracting the appropriate position of the angle reading position from the most probable value N obtained from the regression analysis with respect to the angle φ.

In an encoder provided with a scale plate in which an angle scale is formed, a line sensor for reading the angle scale, and an arithmetic means for obtaining an angle measurement value by interpolating from the read angle scale,
A pair of dot patterns are formed on the dial plate at positions that are symmetrical with respect to the diameter of the dial plate and can be received by the line sensor,
An encoder characterized in that an angle reading position Pr ″ for actually reading the angle scale is determined and stored by the following equation on coordinates along the line sensor.
Pr ″ = c _m ′ − (P′−c _m ′) Scm / (Sp′−Scm)
However, when the angle formed between the plane perpendicular to the rotation axis of the scale plate and the line sensor is φ, the c _m ′ is the midpoint of the two intersections between the center line of the light receiving area of the line sensor and the concentric pattern. The coordinate, P ′ is the most probable value obtained by regression analysis of the position of the foot of the perpendicular drawn from the center of the scale plate to the line sensor, and the Scm is the coordinate c _m ′ of the midpoint of the pair of point patterns The slope of the function fcm (φ) obtained by subtracting the appropriate position of the angle reading position from the angle φ, and Sp ′ is the position of the vertical foot drawn from the center of the scale plate to the line sensor by regression analysis. This is the slope of the function fp ′ (φ) obtained by subtracting the appropriate position of the angle reading position from the accuracy value P ′ with respect to the angle φ.

In an encoder provided with a scale plate in which an angle scale is formed, a line sensor for reading the angle scale, and an arithmetic means for obtaining an angle measurement value by interpolating from the read angle scale,
A pair of dot patterns are formed on the dial plate at positions that are symmetrical with respect to the diameter of the dial plate and can be received by the line sensor,
An encoder characterized in that an angle reading position Pr ″ for actually reading the angle scale is determined and stored by the following equation.
Pr ″ = c _m ′ − (N−c _m ′) Scm / (Sp′−Scm)
However, when the angle formed between the plane perpendicular to the rotation axis of the scale plate and the line sensor is φ, the c _m ′ is the midpoint of the two intersections between the center line of the light receiving area of the line sensor and the concentric pattern. The coordinate, N is the most probable value obtained from regression analysis of the position where the interval of the angle scale read by the line sensor is minimum, and the Scm is the midpoint of the pair of point patterns read by the line sensor An inclination of the function fcm (φ) obtained by subtracting an appropriate position of the angle reading position from the coordinate _cm ′ with respect to the angle φ, and Sp ′ is a regression analysis of the position where the interval of the angle scale read by the line sensor is minimized. Is the slope of the function fp ′ (φ) obtained by subtracting the appropriate position of the angle reading position from the most probable value N obtained from

In an encoder provided with a scale plate in which an angle scale is formed, a line sensor for reading the angle scale, and an arithmetic means for obtaining an angle measurement value by interpolating from the read angle scale,
An encoder characterized in that an angle reading position Pr ″ for actually reading the angle scale is determined and stored by the following equation on coordinates along the line sensor.
Pr ″ = c _m ″ − (P′−c _m ″) Scm / (Sp′−Scm)
However, when the angle formed between the plane perpendicular to the rotation axis of the scale plate and the line sensor is φ, the c _m ″ is the coordinates of the midpoint of the position of the angle scale received by the line sensor, P ′ is the most probable value obtained from regression analysis of the position of the foot of the perpendicular drawn from the center of the scale plate to the line sensor, and Scm is the coordinate of the midpoint of the position of the angle scale received by the line sensor The slope of the function fcm (φ) obtained by subtracting the appropriate position of the angle reading position from c _m ″ with respect to the angle φ, and Sp ′ is the position of the vertical foot drawn from the center of the scale plate to the line sensor from the regression analysis This is the slope of the function fp ′ (φ) obtained by subtracting the appropriate position of the angle reading position from the obtained most probable value P ′ with respect to the angle φ.

In an encoder provided with a scale plate in which an angle scale is formed, a line sensor for reading the angle scale, and an arithmetic means for obtaining an angle measurement value by interpolating from the read angle scale,
An encoder characterized in that an angle reading position Pr ″ for actually reading the angle scale is determined and stored by the following equation.
Pr ″ = c _m ″ − (N−c _m ″) Scm / (Sp′−Scm)
However, when the angle between the plane perpendicular to the rotary axis of the scale plate and the line sensor is φ, c _m ″ is the coordinates of the midpoint of the position of the angle scale received by the line sensor, and the N Is the most probable value obtained by regression analysis of the position where the interval of the angle scales read by the line sensor is minimum, and Scm is the coordinate c _m ″ of the midpoint positions of the angle scales received by the line sensor. The slope of the function fcm (φ) obtained by subtracting the appropriate position of the angle reading position from the angle φ, and Sp ′ is the maximum position obtained from the regression analysis by determining the position at which the interval of the angle scale read by the line sensor is minimum. This is the slope of the function fp ′ (φ) obtained by subtracting the appropriate position of the angle reading position from the accuracy value N with respect to the angle φ.

The encoder according to claim 1, 2, 3, 4, 5 or 6, wherein the value of Scm / (Sp'-Scm) is corrected according to a distance from the rotation axis to the line sensor. .