JPH0921654A - Optical displacement detector and method therefor - Google Patents
Optical displacement detector and method thereforInfo
- Publication number
- JPH0921654A JPH0921654A JP19113295A JP19113295A JPH0921654A JP H0921654 A JPH0921654 A JP H0921654A JP 19113295 A JP19113295 A JP 19113295A JP 19113295 A JP19113295 A JP 19113295A JP H0921654 A JPH0921654 A JP H0921654A
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- optical
- grating
- optical grating
- signal
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は光学式変位検出装置およ
び検出方法に関し、とくに、測定対象物の固定側に取り
付けられた変位検出用メインスケールと測定対象物の可
動側に取り付けられた変位検出用インデックススケール
とを相対変位させた時に生じる変位検出用光信号をとら
え、測定対象物の相対移動変位を検出する光学式変位検
出装置の改良に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical displacement detecting device and a detecting method, and more particularly, to a displacement detecting main scale mounted on a fixed side of a measuring object and a displacement detecting attached on a movable side of the measuring object. The present invention relates to an improvement in an optical displacement detection device which detects a relative displacement of an object to be measured by capturing a displacement detection optical signal generated when the displacement index scale is relatively displaced.
【０００２】[0002]
【従来の技術】一般に、位置決め装置等に用いられる変
位センサには透過形、あるいは反射形光学式変位センサ
が用いられており、一方にメインスケール、他方にイン
デックススケールを含む検出系で構成され、メインスケ
ールとインデックススケールが相対変位すると受光素子
における受光信号が周期的に変化するためにメインスケ
ールとインデックススケールの相対移動変位を検出でき
る。ところが、このような変位検出装置において分解能
を高めるには、メインスケール及びインデックススケー
ルの光学格子ピッチを微細にすることによって、高分解
能化を図っている。この場合、回折等の影響を避けるた
めに、光学格子ピッチが微細になるにしたがって、両ス
ケール間ギャップを光学格子ピッチに相当する程度に狭
くする必要があった。このため、機構精度、アライメン
ト等で高精度なものが必要であった。このような問題点
に対して、両光学格子間ギャップをｍｍオーダと光学格
子ピッチに比べ十分大きく設定可能な方法としては、米
国特許第３８１２３５２号で開示されているような回折
型の変位検出装置が提案されている。ところで、この種
のインクリメンタル型変位センサでの出力は、格子ピッ
チに比例した正弦波状の周期信号であるため、１周期以
上の変位を検出する際にはメインスケール上の１点を原
点とする原点検出機構を備える必要がある。この原点を
検出する方法としては、図４に示すように、インデック
ススケールＩＳ及びメインスケールＭＳに、変位検出用
インデックス光学格子ＩＬや変位検出用メイン光学格子
ＭＬとは別に、同一のランダムパターンの原点検出用メ
イン光学格子ＯＭＬ及び原点検出用インデックス光学格
子ＯＩＬを形成している。原点検出用メイン光学格子Ｏ
ＭＬ及び原点検出用インデックス光学格子ＯＩＬで変調
された信号は、図５に示すように、実線で示すような原
点検出用光信号のピークＶp を検出し、絶対原点を特定
する方法が開示されている。この原点検出法において
は、両スケールのギャップが広くなった場合には、図５
の中で破線で示すように検出原点信号ピークがさがり、
基準電圧Ｖref における原点信号の幅がＷからＷ’のよ
うに大きくなり原点検出精度が悪くなるという問題があ
った。この対策としては、図６に示すような改良案（特
開昭６１ー２１２７２７）が開示されている。すなわ
ち、基準検出用光学窓Ｌ０と検出対象物の固定側に取り
付けられるメインスケールＭＳの変位検出用固定光学格
子Ｌ１と検出対象物可動側に取り付けられるインデック
ススケールＩＳの変位検出用可動光学格子Ｌ２とは別
に、原点検出のため、変位信号周期より長い周期信号を
発生させる原点検出用固定光学格子Ｌ３と光透過、また
は反射特性を有する参照マークＬ４をメインスケールＭ
Ｓに設け、これに対応した光学窓Ｌ５と原点検出用可動
光学格子Ｌ６をインデックススケールＩＳに設け、各光
学格子および光学窓に対応して光源Ｆと受光素子Ｒとを
設けて、高精度な絶対原点を検出する変位検出装置が開
示されている。2. Description of the Related Art Generally, a transmission type or a reflection type optical displacement sensor is used as a displacement sensor used in a positioning device or the like, and is composed of a detection system including a main scale on one side and an index scale on the other side. When the main scale and the index scale are displaced relative to each other, the light receiving signal in the light receiving element changes periodically, so that the relative movement displacement of the main scale and the index scale can be detected. However, in order to improve the resolution in such a displacement detection device, the resolution is increased by making the optical grid pitches of the main scale and the index scale finer. In this case, in order to avoid the influence of diffraction or the like, it is necessary to narrow the gap between both scales to an extent corresponding to the optical grating pitch as the optical grating pitch becomes finer. For this reason, it is necessary to have a high degree of accuracy in terms of mechanism accuracy and alignment. In order to solve such a problem, as a method capable of setting the gap between both optical gratings to be sufficiently larger than the mm order and the optical grating pitch, a diffraction type displacement detecting device as disclosed in US Pat. No. 3,812,352. Is proposed. By the way, since the output of this type of incremental displacement sensor is a sinusoidal periodic signal proportional to the grating pitch, when detecting a displacement of one period or more, one point on the main scale is used as the origin. It is necessary to have a detection mechanism. As a method of detecting the origin, as shown in FIG. 4, the origin of the same random pattern is provided on the index scale IS and the main scale MS, separately from the displacement detecting index optical grating IL and the displacement detecting main optical grating ML. The detection main optical grating OML and the origin detection index optical grating OIL are formed. Main optical grating O for origin detection
As for the signal modulated by the ML and the origin detection index optical grating OIL, as shown in FIG. 5, a method of detecting the peak V p of the origin detection optical signal as shown by the solid line and specifying the absolute origin is disclosed. ing. In this origin detection method, when the gap between both scales becomes wide,
As shown by the broken line in the
There has been a problem that the width of the origin signal at the reference voltage V ref is increased from W to W ′ and the origin detection accuracy is deteriorated. As a countermeasure against this, an improvement plan (Japanese Patent Laid-Open No. 61-212727) as shown in FIG. 6 is disclosed. That is, the reference detection optical window L0, the displacement detection fixed optical grating L1 of the main scale MS mounted on the fixed side of the detection target, and the displacement detection movable optical grating L2 of the index scale IS mounted on the detection target movable side. Separately, in order to detect the origin, a fixed optical grating L3 for origin detection that generates a periodic signal longer than the displacement signal period and a reference mark L4 having a light transmission or reflection characteristic are provided on the main scale M.
The optical window L5 and the movable optical grating L6 for origin detection corresponding thereto are provided on the index scale IS, and the light source F and the light receiving element R are provided corresponding to each optical grating and the optical window to achieve high precision. A displacement detection device that detects an absolute origin is disclosed.
【０００３】[0003]
【発明が解決しようとする課題】前記の改良された従来
法においては、メインスケールでは少なくとも変位検出
用固定光学格子、及び原点検出用固定光学格子を平行に
並べる必要があり、このためメインスケールは大型にな
り、更に光源−光学格子−受光素子が１対１に対応して
いるため、インデックススケールおよび検出系含む変位
検出装置全体が大型になるという問題があった。本発明
は前記従来の問題点を解決するために、スケール間ギャ
ップが大きくとれる光学式変位検出装置において光学装
置が小型、かつ絶対原点を精度良く検出が可能な絶対原
点検出機能を備えた光学式変位検出装置および検出方法
を提供することを目的とする。In the improved conventional method described above, at least the fixed optical grating for detecting displacement and the fixed optical grating for detecting origin must be arranged in parallel in the main scale. There is a problem in that the size of the displacement detecting device including the index scale and the detection system becomes large because the size of the device is large and the light source, the optical grating, and the light receiving element have a one-to-one correspondence. In order to solve the above-mentioned conventional problems, the present invention is an optical displacement detection device in which the gap between scales can be large, and the optical device is small in size and has an absolute origin detection function capable of accurately detecting the absolute origin. An object is to provide a displacement detection device and a detection method.
【０００４】[0004]
【課題を解決するための手段】上記課題を解決するた
め、本発明は、相対移動する一方の部材に固定され、格
子ピッチＰなる第１光学格子と一部にランダムパターン
からなる原点検出用メイン光学格子とが形成された反射
形メインスケールと、相対移動する他方の部材に固定さ
れ、拡散照明光を射出する光源と、前記光源からの照明
光を通して前記メインスケールを照明する格子ピッチＰ
の第２光学格子と、前記第２光学格子から入射した光が
前記第１光学格子によって反射した反射光を通す互いに
９０度位相差を持つ二つの光学格子からなる格子ピッチ
Ｐの第３光学格子と、前記原点検出用メイン光学格子と
同一のランダムパターンよりなる原点検出用インデック
ス光学格子と、前記二つの第３光学格子および前記原点
検出用インデックス光学格子の入射光をそれぞれ検出す
る第１、第２および第３受光素子とを設けたインデック
ススケールと、前記第３光学格子の入射光を検出する第
１受光素子から変位信号を出力する変位信号処理回路
と、前記原点検出用インデックス光学格子の入射光を検
出する第３受光素子から原点信号を出力する原点信号処
理回路とを設けた信号処理回路とを備えた光学式変位検
出装置において、前記光源からの照明光を通して前記メ
インスケールを照明する格子ピッチ２Ｐの第４光学格子
と、前記第４光学格子から入射した光が前記第１光学格
子によって反射した反射光を通す第５光学格子と、前記
第５光学格子の入射光を検出する第４受光素子とを前記
インデックススケールに設け、前記第４受光素子から原
点検出補助信号を出力する原点検出補助信号処理回路
と、前記変位信号と前記原点信号と前記原点検出補助信
号との論理積を出力する論理回路とを前記信号処理回路
に設け、前記第３光学格子の格子ピッチＰなる光学経路
を介して前記第１受光素子によって検出されるＰ／２な
る周期の変位信号と、前記第５光学格子のピッチ２Ｐな
る光学経路を介して前記第４受光素子によって検出され
る周期Ｐなる原点検出補助信号と、前記原点検出用ラン
ダムパターンを介して前記第３受光素子により検出され
る原点信号との論理積から得られる信号から絶対原点を
検出するものである。In order to solve the above-mentioned problems, the present invention is directed to a main point detecting main body which is fixed to one member that moves relatively and has a first optical grating having a grating pitch P and a random pattern partially. A reflection type main scale on which an optical grating is formed, a light source that is fixed to the other member that moves relatively, emits diffused illumination light, and a grating pitch P that illuminates the main scale through the illumination light from the light source.
Second optical grating and a third optical grating having a grating pitch P of two optical gratings having a 90-degree phase difference with each other through which the light incident from the second optical grating passes the reflected light reflected by the first optical grating. And an origin detecting index optical grating having the same random pattern as the origin detecting main optical grating, and first and second detecting the incident light of the two third optical gratings and the origin detecting index optical grating, respectively. An index scale provided with the second and third light receiving elements, a displacement signal processing circuit for outputting a displacement signal from the first light receiving element for detecting the incident light of the third optical grating, and an incidence of the origin detecting index optical grating. An optical displacement detection device comprising a signal processing circuit provided with an origin signal processing circuit for outputting an origin signal from a third light receiving element for detecting light, A fourth optical grating having a grating pitch of 2P that illuminates the main scale through illumination light from a light source, and a fifth optical grating through which the light incident from the fourth optical grating passes through the reflected light reflected by the first optical grating, An origin detection auxiliary signal processing circuit that provides a fourth light receiving element that detects incident light of the fifth optical grating on the index scale, and outputs an origin detection auxiliary signal from the fourth light receiving element, the displacement signal, and the origin. A logic circuit that outputs a logical product of a signal and the origin detection auxiliary signal is provided in the signal processing circuit, and P detected by the first light receiving element via an optical path having a grating pitch P of the third optical grating. A displacement signal having a period of / 2, an origin detection auxiliary signal having a period P detected by the fourth light receiving element via an optical path having a pitch 2P of the fifth optical grating, and And it detects the absolute origin from a signal obtained from the logical product of the origin signal detected by said via a random pattern out inspections third light receiving element.
【０００５】[0005]
【作用】上記手段により、格子ピッチＰの第２光学格子
と、互いに９０度位相差を持つ二つの光学格子からなる
格子ピッチＰの第３光学格子と、ランダムパターンより
なる原点検出用インデックス光学格子と、格子ピッチ２
Ｐの第４光学格子と、格子ピッチ２Ｐの第５光学格子
と、原点検出のための透明光学窓とをインデックススケ
ールに一括して設け、拡散光光源によって第２光学格子
と、第４光学格子と、透明光学窓とを、拡散光光源によ
り一括照明するので、必要な光源数を減らす光学系の小
型となると共に、変位信号及び原点検出補助信号用光学
格子を共用するためメインスケールは幅を小さく小型化
がでる。また、絶対原点特定時に原点検出補助信号を用
いるので、原点検出信号の幅が少々変動しても絶対原点
を高精度に特定できる。By the above means, the second optical grating having the grating pitch P, the third optical grating having the grating pitch P composed of two optical gratings having a 90-degree phase difference with each other, and the index detecting optical grating having a random pattern are provided. And the grid pitch 2
A fourth optical grating of P, a fifth optical grating having a grating pitch of 2P, and a transparent optical window for origin detection are collectively provided on the index scale, and a second optical grating and a fourth optical grating are provided by a diffused light source. Since the transparent optical window and the transparent optical window are collectively illuminated by the diffused light source, the size of the optical system is reduced to reduce the number of required light sources, and the main scale has a wide width to share the optical grating for the displacement signal and the origin detection auxiliary signal. Can be made smaller and smaller. Further, since the origin detection auxiliary signal is used when the absolute origin is specified, the absolute origin can be specified with high accuracy even if the width of the origin detection signal slightly changes.
【０００６】[0006]
【実施例】以下、本発明を図に示す実施例について説明
する。図１は本発明の実施例を示す斜視図である。図に
おいて、１は反射形のメインスケールで、相対移動する
一方の部材（図示せず）に固定され、格子ピッチＰなる
第１光学格子２と、原点検出のため一部にランダムパタ
ーンでなる原点検出用メイン光学格子３が形成されてい
る。４は相対移動する他方の部材（図示せず）に固定さ
れ、メインスケール１に空隙を介して対向するインデッ
クススケール、５は拡散照明光を射出する光源である。
６Ａはこの光源５からの照明光をメインスケール１に照
射するための格子ピッチＰの第２光学格子、６Ｂ，６Ｃ
は第２光学格子６Ａから入射した光が第１光学格子２に
よって反射した反射光を通す互いに９０度位相差を持つ
二つの光学格子からなる格子ピッチＰの第３光学格子で
ある。７Ａは光源５からの照明光をメインスケール１に
照射する格子ピッチ２Ｐの第４光学格子、７Ｂは第４光
学格子７Ａから入射した光が第１光学格子２に反射した
反射光を通す格子ピッチ２Ｐの第５光学格子、８Ａは原
点検出用の透明光学窓、８Ｂは前記原点検出用メイン光
学格子３と同一のランダムパターンでなる原点検出用イ
ンデックス光学格子である。９は受光素子で、第３光学
格子６Ｂ，６Ｃ、原点検出用インデックス格子８Ｂおよ
び第５光学格子７Ｂを通過した照明光を検出する第１、
第２、第３および第４受光素子９Ａ〜９Ｄで構成されて
いる。BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a perspective view showing an embodiment of the present invention. In the figure, reference numeral 1 is a reflection type main scale, which is fixed to one member (not shown) that relatively moves, a first optical grating 2 having a grating pitch P, and an origin which is partially formed in a random pattern for origin detection. A detection main optical grating 3 is formed. An index scale 4 is fixed to the other member (not shown) that relatively moves, and faces the main scale 1 via a gap. Reference numeral 5 is a light source for emitting diffused illumination light.
6A is a second optical grating having a grating pitch P for irradiating the main scale 1 with the illumination light from the light source 5, and 6B and 6C.
Is a third optical grating having a grating pitch P formed by two optical gratings having a 90-degree phase difference with each other that allows the light incident from the second optical grating 6A to pass through the reflected light reflected by the first optical grating 2. Reference numeral 7A denotes a fourth optical grating having a grating pitch of 2P for irradiating the main scale 1 with illumination light from the light source 5, and 7B denotes a grating pitch for transmitting the light incident from the fourth optical grating 7A and reflected by the first optical grating 2. A 2P fifth optical grating, 8A is a transparent optical window for origin detection, and 8B is an index detecting index optical grating having the same random pattern as the origin detecting main optical grating 3. Reference numeral 9 denotes a light receiving element, which detects the illumination light that has passed through the third optical gratings 6B and 6C, the origin detecting index grating 8B, and the fifth optical grating 7B.
It is composed of second, third and fourth light receiving elements 9A to 9D.
【０００７】図２は各受光素子（９Ａ〜９Ｄ）とオペア
ンプとアンド回路からなる信号処理回路１０のブロック
図である。１１は変位信号処理回路で、第１受光素子９
Ａおよび第２受光素子９Ｂの出力をオペアンプ１１１、
１１２によってアナログ信号に変換され、コンパレータ
１１３、１１４でロジック信号に変換され、変位信号Ｖ
a ，Ｖb として出力される。なお、第１受光素子９Ａお
よび第２受光素子９Ｂで得られる信号は、変位の方向判
別を行うために９０゜位相差がついており、これは第３
格子６Ｂ、６Ｃの光学格子に位相差を付けることによっ
て得られる。１２は原点信号処理回路で、第３受光素子
９Ｃの出力をオペアンプ１２１によってアナログ信号に
変換され、コンパレータ１２２でロジック信号に変換さ
れ、原点信号Ｖ0 として出力される。１３は原点検出補
助信号処理回路で、第４受光素子９Ｄの出力をオペアン
プ１３１によってアナログ信号に変換され、コンパレー
タ１３２でロジック信号に変換され、原点検出補助信号
Ｖs として出力する。また、１４はアンド回路で、二つ
の変位信号の内の一つの変位信号Ｖa と、原点検出補助
信号Ｖs と、原点信号Ｖo との論理積をとり、絶対原点
信号Ｖabs を出力する。FIG. 2 is a block diagram of a signal processing circuit 10 including each light receiving element (9A to 9D), an operational amplifier and an AND circuit. Reference numeral 11 denotes a displacement signal processing circuit, which is the first light receiving element 9
A and the output of the second light receiving element 9B are the operational amplifier 111,
It is converted into an analog signal by 112, converted into a logic signal by the comparators 113 and 114, and the displacement signal V
It is output as a and V b . The signals obtained by the first light receiving element 9A and the second light receiving element 9B have a 90 ° phase difference in order to discriminate the direction of displacement.
It is obtained by adding a phase difference to the optical gratings of the gratings 6B and 6C. Reference numeral 12 denotes an origin signal processing circuit, which converts the output of the third light receiving element 9C into an analog signal by the operational amplifier 121, converts it into a logic signal by the comparator 122, and outputs it as the origin signal V 0 . Reference numeral 13 denotes an origin detection auxiliary signal processing circuit, which converts the output of the fourth light receiving element 9D into an analog signal by the operational amplifier 131, converts it into a logic signal by the comparator 132, and outputs it as the origin detection auxiliary signal V s . Further, 14 is an AND circuit takes the single displacement signal V a of the two displacement signals, and the origin detection auxiliary signal V s, the logical product of the origin signal V o, and outputs the absolute origin signal V abs .
【０００８】次に図３を用いて絶対原点信号Ｖabs を出
力する動作を説明する。変位信号Ｖa は、光源５から放
射された光が第２光学格子６Ａ（格子ピッチＰ）を透過
し、第１光学格子２（格子ピッチＰ）で反射され、第３
光学格子６Ｂ（格子ピッチＰ）を通過し、第１受光素子
９Ａで検出することによって得られる。第１受光素子９
Ａの出力波形は、図３（ａ）に示すようにメインスケー
ル１が相対的にＰ／２変位する毎に、回折光学像による
正弦波信号の波形が得られる。同様に、原点検出補助信
号Ｖs は、光源５から放射された光が第４光学格子７Ａ
（格子ピッチ２Ｐ）を透過し、第１光学格子２（格子ピ
ッチＰ）で反射され、第５光学格子７Ｂ（格子ピッチ２
Ｐ）を通過し、第４受光素子９Ｄで検出することによっ
て得られ、メインスケールが相対的にＰだけ変位する毎
に、図３（ｂ）に示すような幾何光学像による正弦波信
号が得られる。一方、原点信号Ｖo は、光源５から出た
光が透明光学窓８Ａを通過後、原点検出用メイン光学格
子３に当たり、この反射光像が原点検出用インデックス
光学格子８Ｂと一致する原点付近では、第３受光素子９
Ｃにより、図３（ｃ）で示すような原点信号が得られ
る。原点信号Ｖo は、原点信号Ｖo の幅が変位信号Ｖa
の２周期を超えない程度の電圧に設定された基準電圧Ｖ
ref と比較され、図３（ｃ）に示すロジック信号ＶL に
変換される。このロジック信号ＶL と変位信号Ｖaと原
点検出補助信号Ｖs との論理積をアンド回路１４によっ
てとることにより、図３（ｄ）に示すように、変位信号
Ｖa の１／２周期の幅の絶対原点信号Ｖabsを得ること
ができる。したがって、ランダムパターンによる原点信
号Ｖo の振幅、ピークが少々変動したとしても絶対原点
が変動することがなくなる。Next, the operation of outputting the absolute origin signal V abs will be described with reference to FIG. In the displacement signal V a , the light emitted from the light source 5 passes through the second optical grating 6A (grating pitch P) and is reflected by the first optical grating 2 (grating pitch P),
It is obtained by passing through the optical grating 6B (grating pitch P) and detecting by the first light receiving element 9A. First light receiving element 9
As the output waveform of A, as shown in FIG. 3A, a waveform of a sine wave signal by a diffractive optical image is obtained every time the main scale 1 is relatively displaced by P / 2. Similarly, in the origin detection auxiliary signal V s , the light emitted from the light source 5 is the fourth optical grating 7A.
(Grating pitch 2P), is reflected by the first optical grating 2 (Grating pitch P), and is transmitted through the fifth optical grating 7B (Grating pitch 2).
P), and is obtained by detection by the fourth light receiving element 9D, and every time the main scale is relatively displaced by P, a sine wave signal by a geometrical optical image as shown in FIG. 3B is obtained. To be On the other hand, the origin signal V o hits the origin detecting main optical grating 3 after the light emitted from the light source 5 passes through the transparent optical window 8A, and near the origin where the reflected light image coincides with the origin detecting index optical grating 8B. , Third light receiving element 9
With C, an origin signal as shown in FIG. 3C is obtained. The origin signal V o has a displacement signal V a equal to the width of the origin signal V o.
Reference voltage V set to a voltage not exceeding two cycles
It is compared with ref and converted into the logic signal V L shown in FIG. By taking the logical product of the logic signal V L and the displacement signal V a and the origin detection auxiliary signal V s by the AND circuit 14, as shown in FIG. 3 (d), the half cycle of the displacement signal V a The absolute origin signal V abs of the width can be obtained. Therefore, even if the amplitude and peak of the origin signal V o due to the random pattern slightly change, the absolute origin does not change.
【０００９】[0009]
【発明の効果】以上述べたように、本発明によれば、メ
インスケールにおける光学格子を変位検出用及び原点検
出補助信号用として共用するようにしてあるので、メイ
ンスケールが小型になる。更に拡散光光源による一括照
明によっても光学系が小型になる。また絶対原点も上記
原点補助信号を用いるため、ランダムパターンによる原
点信号の振幅、ピークが少々変動したとしても絶対原点
が変動することなく高精度に検出することができ、小
型、かつ絶対原点を精度良く検出が可能な絶対原点検出
機能を備えた光学式変位検出装置および検出方法を提供
できる効果がある。As described above, according to the present invention, since the optical grating in the main scale is commonly used for the displacement detection and the origin detection auxiliary signal, the main scale becomes small. Further, the collective illumination by the diffused light source also makes the optical system compact. In addition, since the absolute origin also uses the origin auxiliary signal, even if the amplitude and peak of the origin signal due to the random pattern fluctuate a little, the absolute origin can be detected with high accuracy without fluctuation, and the compact origin is accurate. There is an effect that it is possible to provide an optical displacement detection device and a detection method having an absolute origin detection function that enables good detection.
【図１】 本発明の実施例を示す斜視図である。FIG. 1 is a perspective view showing an embodiment of the present invention.
【図２】 本発明の信号回路を示すブロック図である。FIG. 2 is a block diagram showing a signal circuit of the present invention.
【図３】 本発明の動作を示す説明図である。FIG. 3 is an explanatory diagram showing the operation of the present invention.
【図４】 従来例を示す正面図である。FIG. 4 is a front view showing a conventional example.
【図５】 従来例の原点信号を示す説明図である。FIG. 5 is an explanatory diagram showing an origin signal of a conventional example.
【図６】 他の従来例を示す斜視図である。FIG. 6 is a perspective view showing another conventional example.
１：メインスケール、 ２：第１光学格子、 ３：原点
検出用メイン光学格子、４：インデックススケール、
５：光源、６Ａ：第２光学格子、６Ｂ、６Ｃ：第３光学
格子、７Ａ：第４光学格子、７Ｂ：第５光学格子、８
Ａ：透明光学窓、８Ｂ：原点検出用インデックス光学格
子、９（９Ａ，９Ｂ，９Ｃ，９Ｄ）：受光素子、１０：
信号処理回路、１１：変位信号処理回路、１２：原点信
号処理回路、１３：原点検出補助信号処理回路。１４
アンド回路1: Main scale, 2: First optical grating, 3: Main optical grating for origin detection, 4: Index scale,
5: light source, 6A: second optical grating, 6B, 6C: third optical grating, 7A: fourth optical grating, 7B: fifth optical grating, 8
A: transparent optical window, 8B: index optical grating for origin detection, 9 (9A, 9B, 9C, 9D): light receiving element, 10:
Signal processing circuit, 11: displacement signal processing circuit, 12: origin signal processing circuit, 13: origin detection auxiliary signal processing circuit. 14
AND circuit
───────────────────────────────────────────────────── フロントページの続き (72)発明者 吉田 康 福岡県北九州市八幡西区黒崎城石２番１号 株式会社安川電機内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasushi Yoshida 2-1, Kurosaki Shiroishi, Hachiman Nishi-ku, Kitakyushu City, Fukuoka Prefecture Yasukawa Electric Co., Ltd.
Claims (2)
子ピッチＰなる第１光学格子と一部にランダムパターン
からなる原点検出用メイン光学格子とが形成された反射
形メインスケールと、 相対移動する他方の部材に固定され、拡散照明光を射出
する光源と、前記光源からの照明光を通して前記メイン
スケールを照明する格子ピッチＰの第２光学格子と、前
記第２光学格子から入射した光が前記第１光学格子によ
って反射した反射光を通す互いに９０度位相差を持つ二
つの光学格子からなる格子ピッチＰの第３光学格子と、
前記原点検出用メイン光学格子と同一のランダムパター
ンよりなる原点検出用インデックス光学格子と、前記二
つの第３光学格子および前記原点検出用インデックス光
学格子の入射光をそれぞれ検出する第１、第２および第
３受光素子とを設けたインデックススケールと、 前記第３光学格子の入射光を検出する第１受光素子から
変位信号を出力する変位信号処理回路と、前記原点検出
用インデックス光学格子の入射光を検出する第３受光素
子から原点信号を出力する原点信号処理回路とを設けた
信号処理回路とを備えた光学式変位検出装置において、 前記光源からの照明光を通して前記メインスケールを照
明する格子ピッチ２Ｐの第４光学格子と、前記第４光学
格子から入射した光が前記第１光学格子によって反射し
た反射光を通す第５光学格子と、前記第５光学格子の入
射光を検出する第４受光素子とを前記インデックススケ
ールに設け、 前記第４受光素子から原点検出補助信号を出力する原点
検出補助信号処理回路と、前記変位信号と前記原点信号
と前記原点検出補助信号との論理積を出力する論理回路
とを前記信号処理回路に設けたことを特徴とした光学式
変位検出装置。1. A reflection type main scale, which is fixed to one of the members that move relative to each other and has a first optical grating having a grating pitch P and a main optical grating for origin detection which is partially formed of a random pattern, and a relative movement. A light source fixed to the other member for emitting diffused illumination light, a second optical grating having a grating pitch P for illuminating the main scale through the illumination light from the light source, and light incident from the second optical grating A third optical grating having a grating pitch P, which is formed of two optical gratings having a 90-degree phase difference with each other, which transmits the reflected light reflected by the first optical grating,
An origin detecting index optical grating having the same random pattern as that of the origin detecting main optical grating, and first, second and second detecting the respective incident lights of the two third optical gratings and the origin detecting index optical grating. An index scale provided with a third light receiving element, a displacement signal processing circuit that outputs a displacement signal from the first light receiving element that detects the incident light of the third optical grating, and an incident light of the origin detecting index optical grating An optical displacement detection device comprising an origin signal processing circuit for outputting an origin signal from a third light receiving element for detection, and a grating pitch 2P for illuminating the main scale through illumination light from the light source. Of the fourth optical grating, and fifth light through which the light incident from the fourth optical grating passes the reflected light reflected by the first optical grating. A grating and a fourth light receiving element for detecting incident light of the fifth optical grating are provided on the index scale, an origin detection auxiliary signal processing circuit for outputting an origin detection auxiliary signal from the fourth light receiving element, and the displacement signal. An optical displacement detection device, wherein: the signal processing circuit is provided with a logic circuit that outputs a logical product of the origin signal and the origin detection auxiliary signal.
い、前記第３光学格子の格子ピッチＰなる光学経路を介
して前記第１受光素子によって検出されるＰ／２なる周
期の変位信号と、前記第５光学格子のピッチ２Ｐなる光
学経路を介して前記第４受光素子によって検出される周
期Ｐなる原点検出補助信号と、前記原点検出用ランダム
パターンを介して前記第３受光素子により検出される原
点信号との論理積から得られる信号から絶対原点を検出
することを特徴とする光学式変位検出方法。2. A displacement signal having a period of P / 2 detected by the first light receiving element via an optical path having a grating pitch P of the third optical grating, using the optical displacement detection device according to claim 1. And an origin detection auxiliary signal having a period P detected by the fourth light receiving element via the optical path having the pitch 2P of the fifth optical grating, and detected by the third light receiving element via the random pattern for origin detection. An optical displacement detection method, characterized in that an absolute origin is detected from a signal obtained from a logical product of the origin signal and the generated origin signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19113295A JPH0921654A (en) | 1995-07-03 | 1995-07-03 | Optical displacement detector and method therefor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19113295A JPH0921654A (en) | 1995-07-03 | 1995-07-03 | Optical displacement detector and method therefor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0921654A true JPH0921654A (en) | 1997-01-21 |
Family
ID=16269419
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP19113295A Pending JPH0921654A (en) | 1995-07-03 | 1995-07-03 | Optical displacement detector and method therefor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0921654A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009069038A (en) * | 2007-09-14 | 2009-04-02 | Canon Inc | Absolute position measuring device |
| JP2010122224A (en) * | 2008-11-20 | 2010-06-03 | Mitsutoyo Corp | Optical fiber interference type grid encoder which can detect reference signal |
| JP2011252713A (en) * | 2010-05-31 | 2011-12-15 | Yaskawa Electric Corp | Linear encoder, linear motor, and linear motor system |
-
1995
- 1995-07-03 JP JP19113295A patent/JPH0921654A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009069038A (en) * | 2007-09-14 | 2009-04-02 | Canon Inc | Absolute position measuring device |
| JP2010122224A (en) * | 2008-11-20 | 2010-06-03 | Mitsutoyo Corp | Optical fiber interference type grid encoder which can detect reference signal |
| JP2011252713A (en) * | 2010-05-31 | 2011-12-15 | Yaskawa Electric Corp | Linear encoder, linear motor, and linear motor system |
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