JPS6166926A - Rotary encoder - Google Patents
Rotary encoderInfo
- Publication number
- JPS6166926A JPS6166926A JP18915484A JP18915484A JPS6166926A JP S6166926 A JPS6166926 A JP S6166926A JP 18915484 A JP18915484 A JP 18915484A JP 18915484 A JP18915484 A JP 18915484A JP S6166926 A JPS6166926 A JP S6166926A
- Authority
- JP
- Japan
- Prior art keywords
- light
- rotation
- radiation grating
- diffracted
- light beams
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000005855 radiation Effects 0.000 claims description 47
- 230000004907 flux Effects 0.000 claims description 7
- 230000010287 polarization Effects 0.000 claims description 7
- 238000005286 illumination Methods 0.000 claims description 6
- 238000001514 detection method Methods 0.000 abstract description 9
- 230000005540 biological transmission Effects 0.000 abstract 1
- 230000001678 irradiating effect Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 6
- 238000005259 measurement Methods 0.000 description 6
- 238000000034 method Methods 0.000 description 5
- 230000007423 decrease Effects 0.000 description 2
- 238000007493 shaping process Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
- G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
- G01D5/36—Forming the light into pulses
- G01D5/38—Forming the light into pulses by diffraction gratings
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P13/00—Indicating or recording presence, absence, or direction, of movement
- G01P13/02—Indicating direction only, e.g. by weather vane
- G01P13/04—Indicating positive or negative direction of a linear movement or clockwise or anti-clockwise direction of a rotational movement
- G01P13/045—Indicating positive or negative direction of a linear movement or clockwise or anti-clockwise direction of a rotational movement with speed indication
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
- G01P3/36—Devices characterised by the use of optical means, e.g. using infrared, visible, or ultraviolet light
- G01P3/366—Devices characterised by the use of optical means, e.g. using infrared, visible, or ultraviolet light by using diffraction of light
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Electromagnetism (AREA)
- Power Engineering (AREA)
- Optical Transform (AREA)
Abstract
Description
【発明の詳細な説明】
本発明はロータリーエンコーダーに関し、′持に円周上
に例えば透光部と反射部の格子模様を複数個、周期的に
刻んだ放射格子を回転物体に取付け、該放射格子K例え
ばレーザーからの光束を照射し、該放射格子からの回折
光を利用して、放射格子若しくは回転物体の回転角度全
光電的に検出するロータリーエンコーダーニ関fるもの
である。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotary encoder, in which a radiation grating in which a plurality of grid patterns of, for example, transparent parts and reflective parts are periodically carved on the circumference is attached to a rotating object, and the radiation grating is This relates to a rotary encoder that irradiates a grating K with a beam of light from, for example, a laser, and uses diffracted light from the radiation grating to photoelectrically detect the rotation angle of the radiation grating or a rotating object.
従来よりフロッピーデスクの駆動等のコンピューター機
器、プリンター専の事務機器、おるいはNC工作機械さ
らにはVTRのキャプステンモーターや回転ドラム等の
回転機構の回転角度を検出する為の手段としてロータリ
ーエンコーダーが利用されてきている。Rotary encoders have traditionally been used as a means to detect the rotation angle of rotating mechanisms such as computer equipment such as floppy desk drives, printer-specific office equipment, NC machine tools, and even VTR capsten motors and rotating drums. It is being used.
光電的表口−タリーエンコーダーを用いる方法は回転軸
に連絡した円板の周囲に透光部と遮光部を等間隔に設け
た、折開メインスケールとこれに対応してメインスケー
ルと等しい間隔で透光部と遮光部とを設けた所を渭固定
のインデックススケールとの双方のスケールを投光手段
と受光手段で(!、167;で対同配置L fC所ti
i1インデックススクール方式の構成を拌っている。こ
の方法はメインスケールの回転に伴って双方のスケール
の透光部と遮光部の間隔に回期したイハ号が得られ、こ
の信−号を波形整形後、vt算することにより回転角度
を検出している。The method using a photoelectric front-tally encoder consists of a fold-out main scale with light-transmitting parts and light-shielding parts provided at equal intervals around a disc connected to the rotation axis, and correspondingly spaced at equal intervals to the main scale. The place where the light-transmitting part and the light-blocking part are provided is set to the fixed index scale, and both scales are arranged in the same manner with the light emitting means and the light receiving means (!, 167;
The composition of the i1 index school system is being changed. In this method, as the main scale rotates, an I/H signal is obtained which is rotated by the interval between the light-transmitting part and the light-blocking part of both scales, and after waveform shaping of this signal, the rotation angle is detected by calculating VT. are doing.
ロータリーエンコーダーでtri 双方(D スケ−#
の透光部と遮光部とのスケール間隔を細かくすればする
程、検出精度を高めることができる。Use the rotary encoder to tri both sides (D scale-#
The finer the scale interval between the light-transmitting part and the light-blocking part, the higher the detection accuracy.
しかしながらスケール間隔を細かくすると回折光の影響
で受光手段からの出力信号のS/N比が低下し検出精度
が低下してしまう欠点がbつた。この為メインスケール
の透光部と遮光部の格子の総本数eti!il定させ、
透光部と遮光部の間隔を回折光の影響を受けない程度ま
で拡大することが考えられる。しかしこれはメインスケ
ールの円板の直径が増大し更に厚さも増大し装置全体が
大型化し、この結果被検回転物体への負荷が大きくなっ
てくる等の欠点があった。However, when the scale interval is made smaller, the S/N ratio of the output signal from the light receiving means decreases due to the influence of the diffracted light, resulting in a decrease in detection accuracy. Therefore, the total number of gratings in the light-transmitting part and the light-blocking part of the main scale is eti! Il determined,
It is conceivable to increase the distance between the light-transmitting part and the light-blocking part to such an extent that it is not affected by diffracted light. However, this has the disadvantage that the diameter and thickness of the main scale disc increases, making the entire device larger, and as a result, the load on the rotating object to be tested increases.
本発明は被検回転物体の負荷を小さくシ、被検回転物体
への取付は偏心の影響を軽減した小型でしかも高精度に
回転角度の検出ができるロータリーエンコーダーの提供
を目的とする。An object of the present invention is to provide a small rotary encoder that reduces the load on a rotating object to be tested, reduces the influence of eccentricity when attached to the rotating object, and is capable of detecting a rotation angle with high precision.
父本発明の更なる目的は放射格子の格子模様の誤差や光
源からの出力レベルの変動に基づく測定誤差を軽減した
高精度のロータリーエンコーダーの提供にある。A further object of the present invention is to provide a highly accurate rotary encoder that reduces measurement errors due to errors in the grid pattern of the radiation grating and fluctuations in the output level from the light source.
本発明の目的を達成する為のロータリーエンコーダーの
主たる特徴は円板の周囲上に格子模様を複数個等角度に
配置した放射格子と前記放射格子と連結した回転物体と
前記放射格子に光束を入射させる為の第1の照明手段と
前記放射格子に入射した前記光束からの回折光のうち特
定の次数の2つの回折光を前記第1の照明手段による光
束の前記放射格子上の入射位itK対する前記回転物体
の回転中心と略点対称の位置に各々図波長板を介して再
度入射させる為の第2の照明手段と前記放射格子により
再度回折された特定の次数の2つの回折光を重ね合わせ
た後、前記重ね合わせた光束管4つの光束に分割する為
の光分割手段と前記光分割手段により分割された4つの
光束を各々偏光方位145度ずつずらした4つの偏光板
を介して受光する為の4つの受光手段々を有し、前記4
つの受光手段からの出力信号を利用して前記回転物体の
回転角度を求めたことである。The main features of the rotary encoder for achieving the object of the present invention are a radiation grating in which a plurality of grid patterns are arranged at equal angles around the circumference of a disk, a rotating object connected to the radiation grating, and a luminous flux incident on the radiation grating. and a first illumination means for causing two diffracted lights of specific orders from among the diffracted lights from the light beam incident on the radiation grating to be set relative to the incident position itK of the light beam by the first illumination means on the radiation grating. Superimposing two diffracted lights of a specific order diffracted again by the second illumination means and the radiation grating, each of which is incident on a position substantially symmetrical with respect to the center of rotation of the rotating object via a wave plate. After that, a light splitting means for splitting the light beams into the four light beams of the superimposed light flux tubes and four polarizing plates each having a polarization direction shifted by 145 degrees receive the four light beams split by the light splitting means. It has four light receiving means for
The rotation angle of the rotating object is determined using output signals from two light receiving means.
次に本発明の一実施例を各図と共に説明する。Next, one embodiment of the present invention will be described with reference to each drawing.
第1図は本発明の一実施例の概略図である。FIG. 1 is a schematic diagram of one embodiment of the present invention.
同図において]はレーザー等の光源、2はコリメーター
レンズ、3〜3.3′〜3イはシリントリカルレンズ、
41,42.41′、4dは反射部、5け円板上に例え
ば透光部と反射部の格子模様を等角度で設けた放射格子
、6け被検回転物体の回転軸、7.7′は蚤波長板でレ
ーザー1からの光束の直線偏光に対してその軸が451
Wと一45度となるように配置されている。In the same figure] is a light source such as a laser, 2 is a collimator lens, 3~3.3'~3a is a cylindrical lens,
41, 42. 41', 4d are reflecting parts, 5 parts are radiation gratings in which, for example, a lattice pattern of transparent parts and reflective parts are provided at equal angles on a disc, 6 parts are the rotation axis of the rotating object to be tested, 7.7 ' is a flea wave plate whose axis is 451 for the linearly polarized light beam from laser 1.
It is arranged at an angle of 145 degrees with W.
8□〜83はビームスプリッタ−19、10、11。8□-83 are beam splitters 19, 10, 11.
12け偏光板で偏光板9 、1(1、11、12は互い
に偏光方位が45度ずつずれるように配置されている。There are 12 polarizing plates, and the polarizing plates 9, 1 (1, 11, and 12) are arranged so that their polarization directions are shifted by 45 degrees from each other.
13 、1/1 、15 、161−を受光素子である
。13, 1/1, 15, and 161- are light receiving elements.
レーザー1より放射された光束はコリメーターレンズ2
により略平行光束となり、シリンドリカルレンズ3□に
よって放射格子5上の位置MI K線状に照射される。The light beam emitted from laser 1 passes through collimator lens 2
As a result, the light beam becomes a substantially parallel light beam, and is irradiated linearly at the position MIK on the radiation grating 5 by the cylindrical lens 3□.
このように線状照射することKより放射格子5上での光
束の照射部分圧相当する透光部と反射部の格子模様のピ
ッチ誤差を軽減することができる。By performing linear irradiation in this manner, it is possible to reduce the pitch error in the grid pattern of the transparent part and the reflective part, which corresponds to the irradiation partial pressure of the light beam on the radiation grating 5.
尚シリンドリカルレンズの代わりにスリット若シくはレ
ンズとスリットを用いて線状照射するようにしても良い
。Incidentally, instead of the cylindrical lens, a slit or a lens and a slit may be used for linear irradiation.
レーザー1からの光束は放射格子5の格子模様によって
反射回折される。いま光束の照射部@M1における格子
模様のピッチをpとすれば±m次の反射回折光り、
、 L20回折角度 θ□は
81]θ1−±mλ/p ・・・・・・・
・・fl+で衣わされる。ここでλけ光束の波長である
。The light beam from the laser 1 is reflected and diffracted by the grating pattern of the radiation grating 5. Now, if the pitch of the lattice pattern at the irradiation part @M1 of the luminous flux is p, then the reflected diffraction light of ±m order,
, L20 diffraction angle θ□ is 81] θ1-±mλ/p ・・・・・・・・・
...is dressed in fl+. Here, λ is the wavelength of the luminous flux.
い1、放射格子5が、角速度ωで回転しているとする。1. Assume that the radiation grating 5 is rotating at an angular velocity ω.
放射格子の回転中心から、照射位置Ml までの距離
をrとすると、照射点M1での周速度は、v−rω と
なる。このとき、±m次の反射回折光の周波数は、次式
で表わされる量だけ、いわゆるドツプラーシフトを受け
る。If the distance from the rotation center of the radiation grating to the irradiation position Ml is r, the circumferential velocity at the irradiation point M1 is v-rω. At this time, the frequency of the ±m-order reflected diffraction light undergoes a so-called Doppler shift by an amount expressed by the following equation.
Δf−±sin em/λ−±ro+sjn 19m/
λ・・・・・・・・・ (2)
そして、シリンドリカルレンズ32,33t−介して、
反射鏡4.4□で、+m次の反射部先光を、回転中心に
略点対称な位置M2に、反射@4’、4□′、5/4波
長板7及び7′、シリンドリカルレンズ3′、33′を
介して、再び線状に照射する。ここで、1/4波長板7
と7′とは、入射するレーザーの直線偏光方位に対して
、各々の軸が、45′及び−45′となるように配置さ
れている。また、照射位tjLM2への入射角は、各々
の回折光に対【7て、照射位置Mよにおける反射回折角
度θ□と等しく、シかも放射格子5の周速度方向との角
度も等しくなるように反射鏡4□′、4゜′が配置され
ている。すると、照射位置M2 において、±m次の
反射回折光は、重なり合い、シリンドリカルレンズ3□
′を透過し再び平行光束となり、3枚のビームスプリッ
タ−8□、8゜、83 Kよって、4光束に分割され、
各々、偏光板9〜12を透過して、受光素子13〜16
に入射する。照射位fit M2で反射され、重なり合
った±m次の回折光は、放射格子5の回転ニ伴って、再
び(2)式のドツプラー周波数シフトΔff受けるので
、照射位置M工で反射したときの周波数シフトと合わせ
て、結局、照射位置M2 で反射される±m次の回折
光の周波数シフト量は±2Δfとなる。このように、±
m次の回折を2回受けた光が重なり合うため、受光素子
13〜16の出力信号の周波数は、2Δf−C−2Δf
)−4Δfとなる。つまり、受光素子13〜16の出力
信号の周波数Fは、F−4Δf −4rmSInθ/λ
となり、(1)式の回折条件の式から、F −4mr
ω/pとなる。放射格子5の格子模様の総本数k N
%等角度ピッチをΔψとすれば、p”−rΔψ、 Δψ
−2π/Nより
F −2mNω/π ・・・・・・・・・
(3)でらる。いま、時間Δtの間での受光素子の出力
佑月の波数e n % Δtの間での放射格子5の回
転角1!toとすれば、n −FJt 、θ−ωΔtよ
りn −2mNθ/π ・・・・・・・・・
(4)となり、受光素子の出力信号波形の波数をカウン
トすることによって、放射格子5の回転角θを、(4)
弐によって求めることができる。Δf−±sin em/λ−±ro+sjn 19m/
λ... (2) And, via the cylindrical lenses 32 and 33t,
Reflector 4.4□ reflects the +m-th order reflected light at a position M2 that is approximately point symmetrical about the center of rotation. ′, 33′, linear irradiation is performed again. Here, 1/4 wavelength plate 7
and 7' are arranged such that their respective axes are 45' and -45' with respect to the linear polarization direction of the incident laser. In addition, the angle of incidence on the irradiation position tjLM2 is equal to the reflection diffraction angle θ□ at the irradiation position M for each diffracted light, and the angle with respect to the circumferential velocity direction of the radiation grating 5 is also equal. Reflecting mirrors 4□' and 4°' are arranged at. Then, at the irradiation position M2, the ±m-order reflected diffraction light overlaps, and the cylindrical lens 3□
', it becomes a parallel beam of light again, and is split into four beams by three beam splitters - 8□, 8°, and 83K.
After passing through the polarizing plates 9 to 12, the light receiving elements 13 to 16
incident on . The overlapping ±m-order diffracted light reflected at the irradiation position M2 undergoes the Doppler frequency shift Δff of equation (2) again as the radiation grating 5 rotates, so the frequency when reflected at the irradiation position M2 is Together with the shift, the amount of frequency shift of the ±m-order diffracted light reflected at the irradiation position M2 becomes ±2Δf. In this way, ±
Since the light that has undergone m-order diffraction twice overlaps, the frequency of the output signal from the light receiving elements 13 to 16 is 2Δf-C-2Δf
)-4Δf. In other words, the frequency F of the output signal of the light receiving elements 13 to 16 is F-4Δf -4rmSInθ/λ
From the diffraction condition equation (1), F −4mr
It becomes ω/p. Total number of grid patterns of the radiation grid 5 k N
If the % equiangular pitch is Δψ, then p”−rΔψ, Δψ
-2π/N from F -2mNω/π ・・・・・・・・・
(3) Come out. Now, the wave number e n % of the output of the light receiving element during the time Δt is the rotation angle of the radiation grating 5 during the time Δt 1! If to, n −FJt, θ−ωΔt, then n −2mNθ/π ・・・・・・・・・
(4), and by counting the wave number of the output signal waveform of the light receiving element, the rotation angle θ of the radiation grating 5 can be calculated as (4)
It can be found by 2.
ところで回転角度を検出する際回転方向が検出jB来れ
ば更に好−ましい。その為本実施例においては従来の光
電式ロータリーエンコーダーなどにおいて公知のように
1複数個の受光素子を用意して、互、いの信号の位相が
9σ°ずれるように配置し、回転に伴590”位相差信
号から、回転方向を示す信号を取り出す方式を用いてい
る。By the way, it is more preferable if the rotation direction is detected when the rotation angle is detected. Therefore, in this embodiment, as is well known in conventional photoelectric rotary encoders, one or more light-receiving elements are prepared and arranged so that the phase of each signal is shifted by 9σ°. ``We use a method to extract a signal indicating the rotation direction from the phase difference signal.
f九、放射格子5の透光部と反射部の線幅の誤差、ある
いけレーザーの出力変動等によって、受光素子の出力信
号の中心レベルが変動する場合がある。そこで本実施例
においてはこの変動を抑えて、中心レベルを一定KL、
後段の信号処理を安定化する為に、180°位相差管も
った2つの出力信号の差動をとって、直流成分を除去す
る、いわゆるブツシュ・プル方式を用いている。The center level of the output signal of the light-receiving element may fluctuate due to f9, an error in the line width between the light transmitting portion and the reflective portion of the radiation grating 5, and fluctuations in the output of the laser beam. Therefore, in this embodiment, this variation is suppressed and the center level is kept at a constant KL.
In order to stabilize the signal processing at the subsequent stage, a so-called bush-pull method is used in which the difference between the two output signals from the 180° phase difference tube is taken and the DC component is removed.
このように本実施例では回転方向を検出すると同時に1
信号の中心レベルを一定にするために、受光素子の出力
信号として、O’、9σ。In this way, in this embodiment, the direction of rotation is detected and at the same time
In order to keep the center level of the signal constant, the output signal of the light receiving element is O', 9σ.
180°、 270”の4つの位相差信号を用いている
。Four phase difference signals of 180° and 270'' are used.
本実施例の構成では、これら4つの位相差信号を、レー
ザーの直線偏光と、2枚の1/4波長板7゜7′と、4
枚の偏光板9〜12の組み合わせで作り出している。一
般にレーザーは直線偏光になっているが、この偏光方位
に対して、±mm次回先光各光路中に、前記のように、
その軸1に45’及び−45′となるようVC3A波長
板7 、7”i−配置する。すると、1/4波長板7,
7′を透過した光束は、互いに逆回りの円偏光となり、
照射位置M2 で再び±m次の反射回折光となって重
なり合うと、再び直線偏光となるが、その偏光方位が、
放射格子5の回転に伴って変化する。この光束を、前記
のように、3枚のビームスプリッタ−8〜83で4光束
に分割し、45′ずつ偏光方位をずらし、た偏光板9〜
12を介して、受光素子13〜16に入射する。受光素
子13〜16からは放射格子5の回転に伴って、90°
ずつ位相がずれた信号が得られることKなる。たとえば
、受光素子13の出力信号の位相金O°とすれば、受光
素子14 、15 、16の出力信号の位相は、各々
90°。In the configuration of this embodiment, these four phase difference signals are transmitted by the linearly polarized light of the laser, two quarter-wave plates 7°7', and
It is produced by a combination of polarizing plates 9 to 12. In general, a laser is linearly polarized light, but with respect to this polarization direction, ±mm in each optical path of the next destination light, as mentioned above,
The VC3A wave plates 7, 7"i- are placed on the axis 1 so that the angles are 45' and -45'. Then, the 1/4 wavelength plates 7,
The light beams transmitted through 7' become circularly polarized light in opposite directions,
At the irradiation position M2, the reflected and diffracted light of order ±m reoccurs and overlaps, becoming linearly polarized light again, but its polarization direction is
It changes as the radiation grating 5 rotates. This light beam is divided into four light beams by the three beam splitters 8 to 83 as described above, and the polarization direction is shifted by 45', and the polarizing plates 9 to 83 are divided into four beams.
The light enters the light receiving elements 13 to 16 via the light receiving element 12 . From the light receiving elements 13 to 16, as the radiation grating 5 rotates,
This means that signals whose phases are shifted by K are obtained. For example, if the phase of the output signal of the light-receiving element 13 is gold O°, the phases of the output signals of the light-receiving elements 14, 15, and 16 are each
90°.
180°、 270’となる。これらの出力信号を、各
々PoIP9o、P18o、P27o とする0第1
因に示したように出力信号P。とP工、。、P9oとP
を各々、差動増幅器20 、21 K入力すると、
差動増幅器20 、21の出力信号間には90°の位相
差があり、しかも各出力信号は、直流成分を除去した、
中心レベル一定の信号圧なっている。180°, 270'. These output signals are PoIP9o, P18o, P27o respectively.
As shown in the above, the output signal P. and P-engineer. , P9o and P
When inputting into the differential amplifiers 20 and 21 K, respectively,
There is a 90° phase difference between the output signals of the differential amplifiers 20 and 21, and each output signal has a direct current component removed.
The signal pressure is constant at the center level.
そして、こわらの信号を波形整形し、回転方向を検出し
た後、カウンターに入れて積算すれば回転角度を求める
ことができる。Then, after shaping the waveform of the stiffness signal and detecting the rotation direction, the rotation angle can be determined by putting it into a counter and integrating it.
ところで、従来から使用されているインデックススケー
ル方式の光電式ロータリーエンコーダーでは、(4)式
に対応する、受光素子からの出力信号の波数nと、メイ
ンスケールの総本数Nと、回転角0との関係は、
n−N672K ・・・・・・・・・(5
)であるから、波数1個あたりの回転角Δ0は、Δθ−
2x/N(ラジアン) ・・・・・・・・・(6
)である。これに対して、本実施例では、(4)式から
、
Δθ−π/2mN (ラジアン) ・・・・・・・
・・(7)である。従って本実施例によれば、同じ分割
数のスケールを用い九場合、従来例の4m倍の回転角検
出精度が得られることに&る。By the way, in the conventionally used index scale type photoelectric rotary encoder, the wave number n of the output signal from the light receiving element, the total number N of the main scale, and the rotation angle 0 correspond to equation (4). The relationship is n-N672K (5
), the rotation angle Δ0 per wavenumber is Δθ−
2x/N (radian) ・・・・・・・・・(6
). On the other hand, in this example, from equation (4), Δθ−π/2mN (radian)
...(7). Therefore, according to this embodiment, when using nine scales with the same number of divisions, it is possible to obtain a rotation angle detection accuracy 4 m times higher than that of the conventional example.
また、従来の光電式ロータリーエンコーダーにおいては
、透光部と遮光部の間隔は、光の回折の影響を考慮する
と、10μm程度が限度である。Further, in a conventional photoelectric rotary encoder, the distance between the light-transmitting part and the light-blocking part is limited to about 10 μm, considering the influence of light diffraction.
いま、回転角検出精度として、たとえば30秒を得るた
めKは、従来例では、メインスケールの分割数として、
(6)式から、N−360X60X60/30−43,
200だけ必要である。そこで、メインスクール最外周
での透光部、遮光部の間隔を 10μmとすれば、メイ
ンスケールの直径は、0.01 tm X43.200
/π−137,5m必要になる。しかるに1本実施例に
よれば、従来例と同じ回転角検出精度を得るためには、
放射格子の分割数は1/4mでよい。±1次の回折光管
用いたm−1の場合、(資)秒の回転角検出精度を得る
ための放射格子5の格子の分割数は、43.200/4
−10.800 1” ヨn。Now, in order to obtain a rotation angle detection accuracy of, for example, 30 seconds, K is the number of divisions of the main scale in the conventional example.
From formula (6), N-360X60X60/30-43,
Only 200 are required. Therefore, if the interval between the light-transmitting part and the light-blocking part at the outermost circumference of the main school is 10 μm, the diameter of the main scale is 0.01 tm x 43.200
/π-137.5m is required. However, according to this embodiment, in order to obtain the same rotation angle detection accuracy as the conventional example,
The number of divisions of the radiation grating may be 1/4 m. In the case of m-1 using a ±1st-order diffraction light tube, the number of grating divisions of the radiation grating 5 to obtain a rotation angle detection accuracy of seconds is 43.200/4.
-10.800 1” Yon.
そして、本実施例においてレーザーの回折光を用いれば
、透光部と反射部の間隔は狭くてよいので、たとえば、
これを4μm とすると、放射格子の直径は、0.00
4 wm X 10,800 /π−1&75 mでよ
いことになる。すなわち、本実施例によれば、従来のイ
ンデックススケール方式の光電式ロータリーエンコーダ
ーと同等の回転角検出精度を得る形状としては、1/1
0以下の大舞さてよいことになる。従って、被検回転物
体への負荷も、従来例とくらべて、はるかに小さくなシ
、正確な測定が行えることKなる。In this embodiment, if laser diffracted light is used, the distance between the transparent part and the reflective part can be narrow, so for example,
If this is 4 μm, the diameter of the radiation grating is 0.00
4 wm x 10,800/π-1 & 75 m would suffice. In other words, according to this embodiment, the shape that achieves the same rotation angle detection accuracy as the conventional index scale type photoelectric rotary encoder is 1/1.
If it's less than 0, then it's a good thing. Therefore, the load on the rotating object to be tested is much smaller than in the conventional example, and accurate measurements can be performed.
第2図は第1図の一部分の放射格子5上の光束の照射位
置M、 、 M2と放射格子5の中心と被検回転物体
の回転中心との偏心の説明図である。FIG. 2 is an explanatory diagram of the irradiation positions M, , M2 of the light beam on the radiation grating 5 of a part of FIG. 1, the eccentricity between the center of the radiation grating 5 and the rotation center of the rotating object to be detected.
本実施例において、放射格子5上の、回転中心に関して
点対称な2点M1 、M2’に照射点、つまり測定点と
し、放射格子5の中心と、被検回転体の回転中心との偏
心の影響を軽減している。すなわち、放射格子5の中心
と、回転中心とを完全に一致させることは困難であり、
両者の偏心は避けられない。たとえば、第2図に示すよ
うに1放射格子5の中心0と、回転中心O/との間に、
偏心数がaだけ6つたとき、回転中心から距離rの位置
にらる測定点M1でのドツプラー周波数シフトは、偏心
がないときとくらべてXr/(r十m) から、r/
(r−a) tで変化する。一方、このとき位置M工
と、回転中心に対して点対称な位置Klる測定点M2で
の周波数シフトは、位[M□での変化とは逆に、r/(
r−m) からr/(r+a) まで変化するから
、位It M、とM2と、同時に2点を測定点とするこ
とによって、偏心の影響を軽減することができる。In this embodiment, two points M1 and M2' on the radiation grating 5 that are symmetrical with respect to the rotation center are used as irradiation points, that is, measurement points, and the eccentricity between the center of the radiation grating 5 and the rotation center of the rotating body to be tested is The impact is being reduced. That is, it is difficult to make the center of the radiation grating 5 and the center of rotation completely coincide,
Eccentricity between the two is inevitable. For example, as shown in FIG. 2, between the center 0 of one radiation grating 5 and the rotation center O/,
When the number of eccentricities increases to 6 by a, the Doppler frequency shift at the measurement point M1 located at a distance r from the center of rotation is from Xr/(r0m) to r/ compared to when there is no eccentricity.
(r-a) Changes at t. On the other hand, at this time, the frequency shift at measurement point M2, which is symmetrical to position M with respect to the center of rotation, is r/(
rm) to r/(r+a), it is possible to reduce the influence of eccentricity by using two points, M and M2, as measurement points at the same time.
第3図は本発明の他の実施例の一部分の概略図であり第
1図の放射格子5に光束が入射する付近を示している。FIG. 3 is a schematic diagram of a portion of another embodiment of the present invention, showing the vicinity where the light beam is incident on the radiation grating 5 of FIG.
同図において各要素に付された番号は第1図で示したも
のと同じ要素を示す。放射格子5の位置MIK入射した
光束の±m次の透過回折光をシリンドリカルレンズ3
.3 .3’、3’ 反射鏡4□、4□、4□′。In the figure, the numbers assigned to each element indicate the same elements as shown in FIG. The position MIK of the radiation grating 5 transmits the ±m-order transmitted diffracted light of the incident light flux through the cylindrical lens 3
.. 3. 3', 3' Reflector 4□, 4□, 4□'.
2 3 2 3’
4□′ を介して回転軸6の中心と略点対称の位置M2
に再度入射させ第1図に示した実施例と同様の効果
を得ている。2 3 2 3'4□' A position M2 that is approximately symmetrical to the center of the rotation axis 6
The same effect as that of the embodiment shown in FIG. 1 is obtained by making the light incident again.
前述した各実施例では±m次の2つの回折光を用いた場
合を示したが±m次の回折光のかわりに次数の異った2
つの回折光を用いても良い。In each of the above-described embodiments, two diffracted lights of the ±m order were used, but instead of the ±m order diffracted lights, two diffracted lights of different orders were used.
Two diffracted lights may be used.
又放射格子上の格子模様を透過部のみ又は反射部のみで
構成l−透過回折光又は反射回折光のみを用いるように
しても良い。Alternatively, the lattice pattern on the radiation grating may be made up of only transmitting portions or only reflecting portions, and only transmitted diffracted light or reflected diffracted light may be used.
又本発明における光源はl/−ザーに限らず単一の波長
全放射する光源であれば使用可能である。Further, the light source in the present invention is not limited to the l/- laser, but any light source that emits all wavelengths of a single wavelength can be used.
以上のように本発明によれば被検回転物体の負荷の小さ
い、放射格子の中心と回転物体の回転中心との偏心誤差
を軽減した小型でしかも高精度のロータリーエンコーダ
ーt−a成することができる。As described above, according to the present invention, it is possible to create a small and highly accurate rotary encoder t-a that has a small load on the rotating object to be tested and reduces the eccentricity error between the center of the radiation grating and the center of rotation of the rotating object. can.
さらに、ブツシュ・プル方式の導入によって、基準と々
る放射格子の線幅不定などKよる受光素子出力の直流変
動分全除去できて、安定した信号処理が可能なロータリ
ーエンコーf−t4成することができる。Furthermore, by introducing the bush-pull method, it is possible to completely eliminate DC fluctuations in the output of the light receiving element due to K, such as the undefined line width of the reference radiation grating, thereby creating a rotary encoder f-t4 that is capable of stable signal processing. I can do it.
第1図は本発明の実施例を示す構成図、第2図は放射格
子の中心と、回転中心との偏心を表わす説明図、第3図
は本発明の別の実施例を示す部分構成図である。
lはレーザー、2はコリメーターレンズ、3□〜33.
3□′〜33′はシリンドリカルレンズ、4□、4□、
4□′、4□′は反射鏡、5は放射格子、6は被検回転
物体の回転軸、7 、7’は号波長板、81〜83はビ
ームスプリッタ−19〜12は偏光板、13〜16は受
光素子である。Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is an explanatory diagram showing the eccentricity between the center of the radiation grating and the center of rotation, and Fig. 3 is a partial block diagram showing another embodiment of the present invention. It is. 1 is a laser, 2 is a collimator lens, 3□~33.
3□' to 33' are cylindrical lenses, 4□, 4□,
4□', 4□' are reflecting mirrors, 5 is a radiation grating, 6 is the rotation axis of the rotating object to be tested, 7, 7' are wave plates, 81 to 83 are beam splitters, 19 to 12 are polarizing plates, 13 -16 are light receiving elements.
Claims (1)
た放射格子と前記放射格子と連結した回転物体と前記放
射格子に光束を入射させる為の第1の照明手段と前記放
射格子に入射した前記光束からの回折光のうち特定の次
数の2つの回折光を前記第1の照明手段による光束の前
記放射格子上の入射位置に対する前記回転物体の回転中
心と略点対称の位置に各々1/4波長板を介して再度入
射させる為の第2の照明手段と前記放射格子により再度
回折された特定の次数の2つの回折光を重ね合わせた後
、前記重ね合わせた光束を4つの光束に分割する為の光
分割手段と前記光分割手段により分割された4つの光束
を各々偏光方位を45度ずつずらした4つの偏光板を介
して受光する為の4つの受光手段とを有し、前記4つの
受光手段からの出力信号を利用して前記回転物体の回転
角度を求めたことを特徴とするロータリーエンコーダー
。(1) A radiation grating in which a plurality of grid patterns are arranged at equal angles around the periphery of a disk, a rotating object connected to the radiation grating, a first illumination means for making a luminous flux incident on the radiation grating, and the radiation grating. Two diffracted lights of a specific order among the diffracted lights from the light beam incident on the beam are placed at a position approximately symmetrical with the center of rotation of the rotating object with respect to the incident position of the light beam by the first illumination means on the radiation grating. After superimposing the two diffracted lights of a specific order that have been diffracted again by the second illumination means and the radiation grating, each of which is made to enter again through a quarter-wave plate, the superimposed luminous flux is divided into four It has a light splitting means for splitting into light beams, and four light receiving means for receiving the four light beams split by the light splitting means through four polarizing plates whose polarization directions are shifted by 45 degrees. , A rotary encoder characterized in that a rotation angle of the rotating object is determined using output signals from the four light receiving means.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP18915484A JPS6166926A (en) | 1984-09-10 | 1984-09-10 | Rotary encoder |
US07/481,684 US4967072A (en) | 1984-09-05 | 1990-02-20 | Interferometric rotating condition detection apparatus |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP18915484A JPS6166926A (en) | 1984-09-10 | 1984-09-10 | Rotary encoder |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS6166926A true JPS6166926A (en) | 1986-04-05 |
JPH0462003B2 JPH0462003B2 (en) | 1992-10-02 |
Family
ID=16236340
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP18915484A Granted JPS6166926A (en) | 1984-09-05 | 1984-09-10 | Rotary encoder |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS6166926A (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH02147816A (en) * | 1988-11-29 | 1990-06-06 | Tokyo Seimitsu Co Ltd | Scale reader |
EP0652487A1 (en) | 1993-10-29 | 1995-05-10 | Canon Kabushiki Kaisha | Rotational deviation detecting method and system using a periodic pattern |
US5442172A (en) * | 1994-05-27 | 1995-08-15 | International Business Machines Corporation | Wavefront reconstruction optics for use in a disk drive position measurement system |
US5909333A (en) * | 1994-05-27 | 1999-06-01 | International Business Machines Corporation | Servo-writing system for use in a data recording disk drive |
JP2005227077A (en) * | 2004-02-12 | 2005-08-25 | Sharp Corp | Optical moving information detector, moving information detecting system, electronic equipment, and encoder |
-
1984
- 1984-09-10 JP JP18915484A patent/JPS6166926A/en active Granted
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH02147816A (en) * | 1988-11-29 | 1990-06-06 | Tokyo Seimitsu Co Ltd | Scale reader |
EP0652487A1 (en) | 1993-10-29 | 1995-05-10 | Canon Kabushiki Kaisha | Rotational deviation detecting method and system using a periodic pattern |
US5550635A (en) * | 1993-10-29 | 1996-08-27 | Canon Kabushiki Kaisha | Rotational deviation detecting method and system using a periodic pattern |
US5442172A (en) * | 1994-05-27 | 1995-08-15 | International Business Machines Corporation | Wavefront reconstruction optics for use in a disk drive position measurement system |
US5909333A (en) * | 1994-05-27 | 1999-06-01 | International Business Machines Corporation | Servo-writing system for use in a data recording disk drive |
JP2005227077A (en) * | 2004-02-12 | 2005-08-25 | Sharp Corp | Optical moving information detector, moving information detecting system, electronic equipment, and encoder |
Also Published As
Publication number | Publication date |
---|---|
JPH0462003B2 (en) | 1992-10-02 |
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