JP4260346B2

JP4260346B2 - Electro-optical element quality determination method and apparatus, and optical voltage sensor manufacturing method

Info

Publication number: JP4260346B2
Application number: JP2000216350A
Authority: JP
Inventors: 一郎小林; 栄一永尾
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2000-07-17
Filing date: 2000-07-17
Publication date: 2009-04-30
Anticipated expiration: 2020-07-17
Also published as: JP2002031583A

Description

【０００１】
【発明の属する技術分野】
この発明は、電圧を測定するための光電圧センサーに用いるポッケルス素子などの電気光学素子の良否を判別する方法及び装置並びに光電圧センサーの製造方法に関し、特に電気光学素子単体で良否を判別することができる電気光学素子の良否判別方法及び装置並びに光電圧センサーの製造方法に関するものである。
【０００２】
【従来の技術】
電力系統の電圧測定には、電圧変成器が広く用いられている。しかしながら、この電圧変成器は測定すべき系統電圧が高くなるほど大型化してしまい、コストおよび設置スペースが嵩むという問題がある。特にＧＩＳと称される不活性ガスを用いたガス絶縁開閉装置では、小型化および省スペース化が強く要求され、このような電圧変成器を搭載することが困難になっている。
このため、近年ポッケルス素子などの電気光学素子を用いた光電圧センサーが用いられるようになってきている。図６は特開平８−２２０１４９号公報に示された光電圧センサーの作用を説明する説明図である。
【０００３】
図６において、１ａは信号処理部の発光ダイオード（図示せず）からの光を光電圧センサーに送る光ファイバー、１ｂは光電圧センサーを通過した光を信号処理部に送る光ファイバー、２ａと２ｂは光ファイバーと光電圧センサーとの光結合を行うコリメータレンズ、３は偏光子、４は１／４波長板、５は電気光学結晶、６は電気光学結晶５の光の通過面に蒸着した透明電極、７は検光子である。また、図７は前記光電圧センサーの電気光学結晶５の正面図を示し、図８は平面図を示している。図７と図８において、８は透明電極６に蒸着された金属電極、９は被測定電圧・電界を金属電極８と透明電極６を介して電気光学結晶５に印加するための外部接続線、１０は光が通過する領域を示し、２０は電気光学結晶５に透明電極６と金属電極８及び外部接続線９を取付けた電気光学素子である。
【０００４】
次に、動作について説明する。
図６において、信号処理部の発光ダイオードから出射された光は光ファイバー１ａを通り、コリメータレンズ２ａを通過して偏光子３に入射し、図のＸ，Ｙ方向に対して４５度のＺ方向の直線偏光だけが透過する。直線偏光は１／４波長板で円偏光に変換され、透明電極６を介して電気光学結晶５に入射する。入射された円偏光は電気光学結晶５の両面に設けられた透明電極６を介して電界が印加されることにより生じる複屈折を利用して、光位相変調を受ける。その後、この光を検光子７を通過させることによりアナログ変調を行い、コリメータレンズ２ｂで集光し、光ファイバー１ｂを介して信号処理部に入力し、アナログ変調の度合に応じた電圧を検出している。
【０００５】
【発明が解決しようとする課題】
光電圧センサーはＧＩＳ等で用いられるため、変調感度が良く、且つ昼夜及び四季の温度変化に影響されることなく安定に動作することが要求されている。このため、製品検査として光電圧センサーを恒温槽に設置し、光電圧センサーに一定電圧を印加した状態で恒温槽内温度を−２０度〜＋６０度まで段階的に変化させて、信号処理部での検出値が許容値内にあることを確認する温度特性試験が不可欠である。前記温度特性の劣化は偏光子や１／４波長板、及び検光子等の光学部品を光電圧センサーに組立る際にも生じるが、主として電気光学結晶自体の良否、透明電極の良否、電気光学結晶５と透明電極６との密着性、透明電極６と金属電極８との密着性、金属電極８と外部接続線９との密着性などに依存している。従来は光電圧センサーに組立て、信号処理部と組合せて、前記温度特性試験を行わなければ電気光学素子２０の良否が判別できないという問題があった。
【０００６】
この発明は、上記のような問題点を解決するためになされたもので、電気光学素子を使用して電圧を測定するように構成された光電圧センサーの温度特性試験を行い、良品の光電圧センサーを選別し、選別された良品の光電圧センサーに使われている電気光学素子の回路素子成分の周波数特性、例えば静電容量の周波数特性を予め測定し、被検査電気光学素子の静電容量の周波数特性を測定し、測定結果が予め測定しておいた周波数特性と略同一であれば、被検査電気光学素子は良品であると判別することにより、光電圧センサーの組立工程や温度特性試験の時間をかけることなく、電気光学素子単体で良否の判別を行うことを可能にした電気光学素子の良否判別方法及び装置を得ることを目的とする。
【０００７】
【課題を解決するための手段】
この発明に係る電気光学素子の良否判別方法は、電気光学素子を使用して電圧を測定するように構成された光電圧センサーの温度特性試験を行い、良品の光電圧センサーを選別する第１の工程、第１の工程で選別された良品の光電圧センサーに使われている電気光学素子の静電容量の周波数特性から求まる静電容量の最大値と共振周波数とを良否判別の基準値として測定する第２の工程、及び被検査電気光学素子の静電容量の周波数特性を測定し、測定結果から求まる静電容量の最大値と共振周波数が第２の工程で得られた静電容量の最大値と共振周波数の基準値近傍の値であれば、被検査電気光学素子は良品であると判別する第３の工程を含むものである。
【０００８】
また、基準値近傍は、静電容量の最大値が基準値±５０％以内、共振周波数が基準値±１％以内に設定されているものである。
【０００９】
さらに、この発明に係る電気光学素子の良否判別装置は、電気光学素子を使用して電圧を測定するように構成された光電圧センサーの温度特性試験を行って良品の光電圧センサーを選別し、良品の光電圧センサーに使われている電気光学素子の静電容量の周波数特性を測定し、得られた静電容量の周波数特性から求まる静電容量の最大値と共振周波数とを基準値として、予め記憶させておく良否判別基準データ記憶部と、被検査電気光学素子の静電容量の周波数特性を測定し、測定結果から求まる静電容量の最大値と共振周波数とが、良否判別基準データ記憶部から読み出された基準値近傍の値であれば、被検査電気光学素子は良品であると判別する良否判別部とを備えたものである。
【００１０】
さらに、基準値近傍は、静電容量の最大値が基準値±５０％以内、共振周波数が基準値±１％以内に設定されているものである。
また、電気光学素子の良否判別装置は、電気光学素子の静電容量の周波数特性の測定を行うインピーダンスアナライザと、良否判別基準データ記憶部及び良否判別部を有するパーソナルコンピュータとで構成されているものである。
さらに、この発明に係る光電圧センサーの製造方法は、電気光学素子を使用して電圧を測定するように構成された光電圧センサーの温度特性試験を行い、良品の光電圧センサーを選別する第１の工程、第１の工程で選別された良品の光電圧センサーに使われている電気光学素子の静電容量の周波数特性から求まる静電容量の最大値と共振周波数とを良否判別の基準値として測定する第２の工程、及び被検査電気光学素子の静電容量の周波数特性を測定し、測定結果から求まる静電容量の最大値と共振周波数が第２の工程で得られた静電容量の最大値と共振周波数の基準値近傍の値であれば、被検査電気光学素子は良品であると判別する第３の工程を含み、第３の工程で良品であると判別された電気光学素子を用いることを特徴とするものである。
【００１１】
【発明の実施の形態】
実施の形態１．
この実施の形態１は、光電圧センサーの温度特性試験を行い、良品の光電圧センサーを選別し、選別された良品の光電圧センサーに使われている電気光学素子の静電容量の周波数特性を予め測定し、被検査電気光学素子の静電容量の周波数特性を測定し、測定結果が予め測定しておいた周波数特性と略同一であれば、被検査電気光学素子は良品であると判別するものである。
以下、図に基づいて詳細に説明する。
図１はこの発明の実施の形態１において電気光学素子の静電容量の周波数特性を測定する測定系の構成を示すブロック図である。図１において、３０は電気光学素子２０の静電容量の周波数特性を測定するインピーダンスアナライザ、３１はインピーダンスアナライザ３０の測定端子である。４０はインピーダンスアナライザ３０の測定値を処理するパーソナルコンピュータ、４５は後述する良否判別基準データ記憶部である。５０はインピーダンスアナライザ３０とパーソナルコンピュータ４０を接続する通信ケーブルである。なお、インピーダンスアナライザ３０とパーソナルコンピュータ４０とはＧＰ−ＩＢで接続されている。
【００１２】
次に、電気光学素子の静電容量の周波数特性を測定する動作を説明する。
先ず、被測定電気光学素子２０の外部接続線をインピーダンスアナライザ３０の測定端子３１に接続する。次に、パーソナルコンピュータ４０はインピーダンスアナライザ３０に測定条件を送信し、インピーダンスアナライザ３０から電気光学素子２０に印加する電圧の周波数を２１０ｋＨｚから２３０ｋＨｚまで５Ｈｚ間隔で変化させると共に、インピーダンスアナライザ３０から周波数とその時の静電容量とを受信する。上記周波数範囲における測定が終わると、パーソナルコンピュータ４０のみで解析処理が行われる。処理内容はグラフ表示と共振周波数及びその静電容量の算出，表示である。
【００１３】
上記周波数範囲が設定されている理由は、使用されている電気光学素子の実測値から機械的共振周波数が２２０ｋＨｚ近傍にあるためで、振動理論（素子寸法，密度，弾性係数等から求まる）による共振周波数ともよく一致している。また、機械的共振点付近では電気共振回路と等価である。
なお、インピーダンスアナライザ３０は、静電容量の周波数特性を直列共振回路として測定しており、直列共振回路は電気光学素子が持っているＬ成分，Ｃ成分，Ｒ成分（これらをまとめて回路素子成分と呼ぶ）によって形成される。この回路素子成分は電気光学素子の物質定数（結晶の密度，誘電率，弾性係数，素子寸法等）で決まる。
【００１４】
次に、電気光学素子の良否判定基準の設定及び良否判別方法についての説明する。
図２は光電圧センサーの温度特性試験結果の良品例を説明する説明図、図３は光電圧センサーの温度特性試験結果の不良品例を説明する説明図である。
温度特性試験の温度変化のパターンは図２または図３に示す通りであり、光電圧センサーは恒温槽内で＋２０°Ｃから＋７０°Ｃに昇温して約２４０時間保持した後＋２０°Ｃに降温し、さらに−２０°Ｃ〜＋６０°Ｃを段階的に変化させるサイクルを３サイクル行った後、＋２０°Ｃで約８時間保持される。光電圧センサーの良否判定は前記温度特性試験において、信号処理部での検出値の偏差が±０．５％以下を良品、他を不良品としている。図２は前記温度特性試験の信号処理部での検出値の偏差の最大値が＋０．２％なので良品であり、図３は前記偏差の最小値が−１．９％なので不良品である。
【００１５】
図４は前記温度特性試験において良品と判別された光電圧センサーの電気光学素子２０の静電容量の周波数特性の一例を示したものである。図に示す通り、共振周波数が２２１．５ｋＨｚ近傍で静電容量が１３０ｐＦになることが分かった。一方、図５は不良と判断された光電圧センサーの電気光学素子２０の静電容量の周波数特性の一例を示したものであり、共振周波数が２２１．６ｋＨｚでの静電容量は３６ｐＦしかないことが分かった。また、表１に光電圧センサーの良品５個と不良品５個について、各電気光学素子２０の静電容量測定の最大値と共振周波数を示す。
【００１６】
【表１】

【００１７】
静電容量の絶対値や共振周波数は電気光学素子の外形寸法等に依存する。そこで、光電圧センサーの温度特性試験で良品と判別された電気光学素子２０の静電容量と共振周波数を基準値とし、その電気光学素子２０と同一外形寸法の電気光学素子２０に対して表１の結果から、電気光学素子２０の良品判定は静電容量の最大値が基準値の±５０％以内、且つ共振周波数が基準値の±１％以内とした。なお、静電容量の最大値の基準値は、良品５個の平均１２１．４ｐＦとし、共振周波数の基準値は、良品５個の平均２２１．５ｋＨｚとしている。
上記のようにして設定された静電容量の最大値の基準値及び共振周波数の基準値は、予めパーソナルコンピューター４０内の良否判別基準データ記憶部４５に記憶させておく。
【００１８】
被検査電気光学素子の良否判別は以下のように行われる。インピーダンスアナライザ３０は、前述と同様の方法で被検査電気光学素子の静電容量の周波数特性の測定を行う。そしてパーソナルコンピュータ４０は、インピーダンスアナライザ３０から取り込んだデータ、即ち周波数とその時の静電容量とに基づいて、検査対象の電気光学素子の静電容量の最大値及び共振周波数を求める。また、良否判別基準データ記憶部４５から基準値を読み出し、検査対象の電気光学素子の静電容量の最大値及び共振周波数が、基準値近傍の値であれば、良品と判定すると共に良品である旨の表示を行う。
なお、基準値近傍の値は、前述のように、静電容量の最大値が基準値の±５０％以内、共振周波数が基準値の±１％以内である。
通常、電気光学素子２０の外形寸法は設計時に決定すれば、変更されることは無いので、一度良品判別基準値が得られれば、以降は対象となる電気光学素子２０単体で良否判別ができる。
【００１９】
なお、実施の形態１は、静電容量の周波数特性から静電容量の最大値と共振周波数とを求め、良否判別の基準値にしているが、予め測定しておいた静電容量の周波数特性をそのまま基準データとして記憶させ、即ち図４に示すグラフの各点のデータを基準データとして記憶させ、被検査電気光学素子の静電容量の周波数特性のデータを各点で基準データと比較して、略同じであれば良品と判別することもできる。
また、静電容量の周波数特性の測定にインピーダンスアナライザを用いているが、周波数特性の測定できる機能がある機種であれば、ＬＣＲメーターでもよい。
また、実施の形態１の電気光学素子はＢｉ₁₂ＧｅＯ₂₀からなるものであるが、Ｂｉ₁₂ＳｉＯ₂₀やＬｉＮｂＯ₃からなる電気光学素子でも、同様に良否が判定できると考えられる。ただし、結晶やその寸法により共振周波数や静電容量は異なる。
また、実施の形態１は、静電容量の周波数特性を測定しているが、他の回路素子成分、例えばインピーダンス（絶対値）の周波数特性やＤの周波数特性を測定しても、同様に電気光学素子の良否を判別することができる。
【００２０】
【発明の効果】
この発明は以上説明したとおり、電気光学素子を使用して電圧を測定するように構成された光電圧センサーの温度特性試験を行い、良品の光電圧センサーを選別する第１の工程、第１の工程で選別された良品の光電圧センサーに使われている電気光学素子の静電容量の周波数特性から求まる静電容量の最大値と共振周波数とを良否判別の基準値として測定する第２の工程、及び被検査電気光学素子の静電容量の周波数特性を測定し、測定結果から求まる静電容量の最大値と共振周波数が第２の工程で得られた静電容量の最大値と共振周波数の基準値近傍の値であれば、被検査電気光学素子は良品であると判別する第３の工程を含むものであるから、電気光学素子単体で光電圧センサーに適するか否かの判別、つまり良否の判別ができ、不良品を光電圧センサー組立工程に流すことを阻止できる。従って、製造時における歩留まりの向上が図れ、且つ３５０時間も要する温度特性試験回数の削減ができるため、生産性が大幅に改善できるという効果を有する。
【００２１】
また、電気光学素子を使用して電圧を測定するように構成された光電圧センサーの温度特性試験を行って良品の光電圧センサーを選別し、良品の光電圧センサーに使われている電気光学素子の静電容量の周波数特性を測定し、得られた静電容量の周波数特性から求まる静電容量の最大値と共振周波数とを基準値として、予め記憶させておく良否判別基準データ記憶部と、被検査電気光学素子の静電容量の周波数特性を測定し、測定結果から求まる静電容量の最大値と共振周波数とが、良否判別基準データ記憶部から読み出された基準値近傍の値であれば、被検査電気光学素子は良品であると判別する良否判別部とを備えたものであるから、電気光学素子単体で光電圧センサーに適するか否かの判別、つまり良否の判別ができ、不良品を光電圧センサー組立工程に流すことを阻止できる。従って、製造時における歩留まりの向上が図れ、且つ３５０時間も要する温度特性試験回数の削減ができるため、生産性が大幅に改善できるという効果を有する。
【図面の簡単な説明】
【図１】この発明の実施の形態１において電気光学素子の静電容量の周波数特性を測定する測定系の構成を示すブロック図である。
【図２】光電圧センサーの温度特性試験結果の良品例を説明する説明図である。
【図３】光電圧センサーの温度特性試験結果の不良品例を説明する説明図である。
【図４】温度特性試験において良品と判別された光電圧センサーの電気光学素子の静電容量の周波数特性の一例を説明する説明図である。
【図５】温度特性試験において不良品と判別された光電圧センサーの電気光学素子の静電容量の周波数特性の一例を説明する説明図である。
【図６】光電圧センサーの作用を説明する説明図である。
【図７】電気光学素子の正面図である。
【図８】電気光学素子の平面図である。
【符号の説明】
９外部接続線、２０電気光学素子、３０インピーダンスアナライザ、
３１測定端子、４０パーソナルコンピュータ、
４５良否判別基準データ記憶部、５０通信ケーブル。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for determining the quality of an electro-optical element such as a Pockels element used in an optical voltage sensor for measuring a voltage, and a method for manufacturing an optical voltage sensor , and in particular, to determine the quality of an electro-optical element alone. The present invention relates to a method and apparatus for determining whether or not an electro-optic element is good and a method for manufacturing a photovoltage sensor .
[0002]
[Prior art]
A voltage transformer is widely used to measure the voltage of the power system. However, the voltage transformer becomes larger as the system voltage to be measured becomes higher, and there is a problem that the cost and installation space increase. In particular, in a gas insulated switchgear using an inert gas called GIS, downsizing and space saving are strongly demanded, and it is difficult to mount such a voltage transformer.
For this reason, in recent years, an optical voltage sensor using an electro-optical element such as a Pockels element has been used. FIG. 6 is an explanatory diagram for explaining the operation of the optical voltage sensor disclosed in Japanese Patent Application Laid-Open No. 8-220149.
[0003]
In FIG. 6, 1a is an optical fiber that sends light from a light emitting diode (not shown) of the signal processing unit to the optical voltage sensor, 1b is an optical fiber that sends light that has passed through the optical voltage sensor to the signal processing unit, and 2a and 2b are optical fibers. A collimator lens for optically coupling the optical voltage sensor to the photovoltage sensor, 3 a polarizer, 4 a quarter wave plate, 5 an electro-optic crystal, 6 a transparent electrode deposited on the light passage surface of the electro-

optic crystal

5, 7 Is an analyzer. FIG. 7 shows a front view of the electro-optic crystal 5 of the photovoltage sensor, and FIG. 8 shows a plan view. 7 and 8, 8 is a metal electrode deposited on the transparent electrode 6, 9 is an external connection line for applying a measured voltage / electric field to the electro-optic crystal 5 through the metal electrode 8 and the transparent electrode 6, Reference numeral 10 denotes an area through which light passes, and 20 denotes an electro-optical element in which a transparent electrode 6, a metal electrode 8, and an external connection line 9 are attached to the electro-optical crystal 5.
[0004]
Next, the operation will be described.
In FIG. 6, the light emitted from the light emitting diode of the signal processing unit passes through the optical fiber 1a, passes through the collimator lens 2a, enters the polarizer 3, and is in the Z direction of 45 degrees with respect to the X and Y directions in the figure. Only linearly polarized light is transmitted. The linearly polarized light is converted into circularly polarized light by the quarter wavelength plate and enters the electro-optic crystal 5 through the transparent electrode 6. The incident circularly polarized light is subjected to optical phase modulation by utilizing birefringence generated by applying an electric field through transparent electrodes 6 provided on both surfaces of the electro-optic crystal 5. Thereafter, this light is passed through the analyzer 7 for analog modulation, collected by the collimator lens 2b, input to the signal processing unit via the optical fiber 1b, and a voltage corresponding to the degree of analog modulation is detected. Yes.
[0005]
[Problems to be solved by the invention]
Since the photovoltage sensor is used in GIS or the like, it is required to have a high modulation sensitivity and to operate stably without being affected by temperature changes during the day and night. For this reason, an optical voltage sensor is installed in a thermostatic chamber for product inspection, and the temperature in the thermostatic chamber is changed stepwise from −20 degrees to +60 degrees with a constant voltage applied to the optical voltage sensor. A temperature characteristic test to confirm that the detected value is within the allowable value is indispensable. The deterioration of the temperature characteristics also occurs when assembling optical components such as a polarizer, a quarter-wave plate, and an analyzer into an optical voltage sensor, but mainly the quality of the electro-optic crystal itself, the quality of the transparent electrode, electro-optics It depends on the adhesion between the crystal 5 and the transparent electrode 6, the adhesion between the transparent electrode 6 and the metal electrode 8, the adhesion between the metal electrode 8 and the external connection line 9, and the like. Conventionally, there has been a problem that whether the electro-optic element 20 is good or bad cannot be determined unless the temperature characteristic test is performed by assembling an optical voltage sensor and combining it with a signal processing unit.
[0006]
The present invention has been made to solve the above-described problems. A temperature characteristic test of an optical voltage sensor configured to measure a voltage using an electro-optic element is performed, and a non-defective optical voltage is obtained. Select the sensor, measure the frequency characteristics of the circuit element components of the electro-optic elements used in the selected non-defective photovoltage sensor, for example, the frequency characteristics of the capacitance, and measure the capacitance of the electro-optic element to be inspected. If the measured frequency characteristics are approximately the same as the frequency characteristics measured in advance, it is determined that the electro-optical element to be inspected is a non-defective product. It is an object of the present invention to provide an electro-optical element quality determination method and apparatus that can determine the quality of a single electro-optical element without taking a long time.
[0007]
[Means for Solving the Problems]
The electro-optical element quality determination method according to the present invention is a first method of selecting a non-defective optical voltage sensor by performing a temperature characteristic test of an optical voltage sensor configured to measure a voltage using the electro-optical element. Measure the capacitance maximum value and resonance frequency obtained from the frequency characteristics of the capacitance of the electro-optic element used in the non-defective photovoltage sensor selected in the process and the first process as the reference values for quality determination Measuring the frequency characteristics of the capacitance of the electro-optical element to be inspected, and determining the maximum capacitance value obtained from the measurement result and the resonance frequency to obtain the maximum capacitance obtained in the second step. If the value is close to the reference value of the resonance frequency, the third step of determining that the electro-optical element to be inspected is a non-defective product is included.
[0008]
In the vicinity of the reference value, the maximum value of the electrostatic capacitance is set within the reference value ± 50%, and the resonance frequency is set within the reference value ± 1%.
[0009]
Furthermore, the electro-optical element quality determination device according to the present invention performs a temperature characteristic test of an optical voltage sensor configured to measure a voltage using the electro-optical element, and selects a non-defective optical voltage sensor, Measure the frequency characteristics of the capacitance of the electro-optic elements used in non-defective photovoltage sensors, and use the maximum capacitance value and the resonance frequency obtained from the frequency characteristics of the obtained capacitance as reference values . A pass / fail judgment reference data storage unit that is stored in advance and a frequency characteristic of the capacitance of the electro-optical element to be inspected are measured, and the maximum capacitance value obtained from the measurement result and the resonance frequency are stored as pass / fail judgment reference data. If the value is in the vicinity of the reference value read from the unit, the electro-optical element to be inspected is provided with a pass / fail discriminating unit that discriminates that the electro-optical element to be inspected is a good product.
[0010]
Further , in the vicinity of the reference value, the maximum capacitance is set within the reference value ± 50% and the resonance frequency is set within the reference value ± 1%.
Further, the electro-optical element quality determination device is composed of an impedance analyzer that measures the frequency characteristics of the capacitance of the electro-optical element, and a personal computer having a quality determination reference data storage unit and a quality determination unit. It is.
Furthermore, the method of manufacturing an optical voltage sensor according to the present invention includes a first method of selecting a non-defective optical voltage sensor by performing a temperature characteristic test of an optical voltage sensor configured to measure a voltage using an electro-optic element. The maximum capacitance value obtained from the capacitance frequency characteristics of the electro-optic element used in the non-defective photovoltage sensor selected in the first step and the resonance frequency are used as reference values for quality determination. The second step of measuring, and the frequency characteristic of the capacitance of the electro-optical element to be inspected are measured, and the maximum value of the capacitance and the resonance frequency obtained from the measurement result are the values of the capacitance obtained in the second step. If the maximum value and a value in the vicinity of the reference value of the resonance frequency include the third step of determining that the electro-optical element to be inspected is non-defective, and the electro-optical element determined to be non-defective in the third step It is characterized by using .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
In the first embodiment, the temperature characteristic test of the photovoltage sensor is performed, the non-defective photovoltage sensor is selected, and the frequency characteristics of the capacitance of the electro-optical element used in the selected non-defective photovoltage sensor are obtained. Measure in advance and measure the frequency characteristics of the capacitance of the electro-optical element to be inspected. If the measurement result is substantially the same as the frequency characteristics measured in advance, it is determined that the electro-optical element to be inspected is a non-defective product. Is.
Hereinafter, it demonstrates in detail based on figures.
FIG. 1 is a block diagram showing the configuration of a measurement system for measuring the frequency characteristics of capacitance of an electro-optic element in Embodiment 1 of the present invention. In FIG. 1, 30 is an impedance analyzer that measures the frequency characteristics of the capacitance of the electro-

optic element

20, and 31 is a measurement terminal of the impedance analyzer 30. Reference numeral 40 denotes a personal computer that processes the measurement value of the impedance analyzer 30, and reference numeral 45 denotes a pass / fail judgment reference data storage unit to be described later. A communication cable 50 connects the impedance analyzer 30 and the personal computer 40. The impedance analyzer 30 and the personal computer 40 are connected by GP-IB.
[0012]
Next, an operation for measuring the frequency characteristics of the capacitance of the electro-optic element will be described.
First, the external connection line of the electro-optical element 20 to be measured is connected to the measurement terminal 31 of the impedance analyzer 30. Next, the personal computer 40 transmits measurement conditions to the impedance analyzer 30 and changes the frequency of the voltage applied from the impedance analyzer 30 to the electro-optic element 20 at intervals of 5 Hz from 210 kHz to 230 kHz. Receive the capacitance. When the measurement in the frequency range is finished, the analysis process is performed only by the personal computer 40. The processing contents are graph display, calculation and display of resonance frequency and its capacitance.
[0013]
The reason why the above frequency range is set is that the mechanical resonance frequency is in the vicinity of 220 kHz from the actual measurement value of the electro-optic element used, and the resonance is based on the vibration theory (determined from the element size, density, elastic coefficient, etc.). The frequency is also in good agreement. Further, it is equivalent to an electric resonance circuit near the mechanical resonance point.
The impedance analyzer 30 measures the frequency characteristics of the capacitance as a series resonance circuit, and the series resonance circuit includes an L component, a C component, and an R component that the electro-optic element has (collectively these circuit element components). Called). This circuit element component is determined by the material constant of the electro-optic element (crystal density, dielectric constant, elastic coefficient, element size, etc.).
[0014]
Next, the setting of the pass / fail judgment criteria for the electro-optic element and the pass / fail judgment method will be described.
FIG. 2 is an explanatory diagram illustrating an example of a non-defective product as a result of the temperature characteristic test of the optical voltage sensor, and FIG. 3 is an explanatory diagram illustrating an example of a defective product as a result of the temperature characteristic test of the optical voltage sensor.
The temperature change pattern of the temperature characteristic test is as shown in FIG. 2 or FIG. 3, and the photovoltage sensor is heated from + 20 ° C. to + 70 ° C. in a constant temperature bath and held for about 240 hours, and then to + 20 ° C. After the temperature is lowered and three cycles of changing from −20 ° C. to + 60 ° C. in stages are performed, the temperature is maintained at + 20 ° C. for about 8 hours. In the temperature characteristic test, the optical voltage sensor is judged to be good when the deviation of the detected value in the signal processing unit is ± 0.5% or less, and the other is defective. FIG. 2 is a non-defective product because the maximum deviation of the detected value in the signal processing section of the temperature characteristic test is + 0.2%, and FIG. 3 is a defective product because the minimum deviation is −1.9%.
[0015]
FIG. 4 shows an example of the frequency characteristics of the capacitance of the electro-optic element 20 of the optical voltage sensor that is determined to be non-defective in the temperature characteristic test. As shown in the figure, it was found that the capacitance was 130 pF when the resonance frequency was around 221.5 kHz. On the other hand, FIG. 5 shows an example of the frequency characteristics of the capacitance of the electro-optic element 20 of the photovoltage sensor determined to be defective, and the capacitance at the resonance frequency of 221.6 kHz is only 36 pF. I understood. Table 1 shows the maximum value of the capacitance measurement of each electro-optic element 20 and the resonance frequency for five non-defective products and five defective products of the optical voltage sensor.
[0016]
[Table 1]

[0017]
The absolute value of the capacitance and the resonance frequency depend on the outer dimensions of the electro-optic element. Therefore, the electrostatic capacity and resonance frequency of the electro-optical element 20 determined as non-defective in the temperature characteristic test of the optical voltage sensor are used as reference values, and Table 1 shows the electro-optical element 20 having the same outer dimensions as the electro-optical element 20. From these results, the non-defective product determination of the electro-optic element 20 was made such that the maximum capacitance was within ± 50% of the reference value and the resonance frequency was within ± 1% of the reference value. In addition, the reference value of the maximum value of the capacitance is 121.4 pF on the average of five good products, and the reference value of the resonance frequency is 221.5 kHz on the average of five good products.
The reference value for the maximum value of the capacitance and the reference value for the resonance frequency set as described above are stored in advance in the pass / fail judgment reference data storage unit 45 in the personal computer 40.
[0018]
The quality determination of the electro-optical element to be inspected is performed as follows. The impedance analyzer 30 measures the frequency characteristics of the capacitance of the electro-optical element to be inspected by the same method as described above. The personal computer 40 obtains the maximum value of the electrostatic capacity and the resonance frequency of the electro-optical element to be inspected based on the data taken from the impedance analyzer 30, that is, the frequency and the electrostatic capacity at that time. Further, the reference value is read from the pass / fail judgment reference data storage unit 45, and if the maximum value of the electrostatic capacitance and the resonance frequency of the electro-optical element to be inspected are values near the reference value, the product is determined to be non-defective and is non-defective. Display to the effect.
As described above, the value near the reference value is such that the maximum capacitance is within ± 50% of the reference value and the resonance frequency is within ± 1% of the reference value.
Normally, the external dimensions of the electro-optical element 20 are not changed once determined at the time of design. Therefore, once the non-defective product determination reference value is obtained, it is possible to determine whether the target electro-optical element 20 alone is acceptable.
[0019]
In the first embodiment, the maximum value of the capacitance and the resonance frequency are obtained from the frequency characteristics of the capacitance, and set as the reference values for pass / fail judgment. However, the frequency characteristics of the capacitance measured in advance. 4 is stored as reference data as it is, that is, the data of each point of the graph shown in FIG. 4 is stored as reference data, and the capacitance frequency characteristic data of the electro-optical element to be inspected is compared with the reference data at each point. If they are substantially the same, it can also be determined as a good product.
Moreover, although the impedance analyzer is used for the measurement of the frequency characteristic of the capacitance, an LCR meter may be used as long as it has a function capable of measuring the frequency characteristic.
Further, although the electro-optic element of the first embodiment is made of Bi ₁₂ GeO _20, it is considered that the quality can be similarly determined even with an electro-optic element made of Bi ₁₂ SiO ₂₀ or LiNbO ₃ . However, the resonance frequency and capacitance vary depending on the crystal and its dimensions.
In the first embodiment, the frequency characteristics of the capacitance are measured. However, even if other circuit element components, for example, the frequency characteristics of impedance (absolute value) and the frequency characteristics of D are measured, the electrical characteristics are similarly obtained. The quality of the optical element can be determined.
[0020]
【The invention's effect】
As described above, the present invention performs a temperature characteristic test of an optical voltage sensor configured to measure a voltage using an electro-optic element, and selects a non-defective optical voltage sensor. Second step of measuring the maximum value of the electrostatic capacitance obtained from the frequency characteristics of the electrostatic capacitance of the electro-optic element used in the non-defective photovoltage sensor selected in the step and the resonance frequency as a reference value for determining pass / fail , And the frequency characteristics of the capacitance of the electro-optical element to be inspected, and the maximum capacitance value and the resonance frequency obtained from the measurement result are the maximum capacitance value and the resonance frequency obtained in the second step . If the value is in the vicinity of the reference value, it includes the third step of determining that the electro-optical element to be inspected is a non-defective product. Therefore, it is determined whether the electro-optical element alone is suitable for the photovoltage sensor, that is, whether the electro-optical element is acceptable. Defective product It can prevent the flow to the photovoltage sensor assembly process. Accordingly, the yield during manufacturing can be improved, and the number of temperature characteristic tests that require 350 hours can be reduced, so that the productivity can be greatly improved.
[0021]
In addition, the electro-optic element used in the non-defective photovoltage sensor is selected by conducting a temperature characteristic test of the photovoltage sensor configured to measure the voltage using the electro-optic element. Measuring the frequency characteristics of the electrostatic capacity, pass / fail judgment reference data storage unit that stores in advance as a reference value the maximum value of the electrostatic capacity and the resonance frequency obtained from the frequency characteristics of the obtained capacitance , Measure the frequency characteristics of the capacitance of the electro-optical element to be inspected, and if the maximum value of the capacitance and the resonance frequency obtained from the measurement result are values near the reference value read from the pass / fail judgment reference data storage unit For example, since the electro-optical element to be inspected is provided with a pass / fail discriminating section that discriminates that the electro-optical element is a non-defective product, it can be determined whether the electro-optical element alone is suitable for the photovoltage sensor, that is, pass / fail determination. Good product with photovoltage It can prevent the flow to Nsa assembly process. Accordingly, the yield during manufacturing can be improved, and the number of temperature characteristic tests that require 350 hours can be reduced, so that the productivity can be greatly improved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a measurement system that measures frequency characteristics of capacitance of an electro-optic element in Embodiment 1 of the present invention.
FIG. 2 is an explanatory diagram for explaining a non-defective example of a temperature characteristic test result of an optical voltage sensor.
FIG. 3 is an explanatory diagram illustrating an example of a defective product as a result of a temperature characteristic test of an optical voltage sensor.
FIG. 4 is an explanatory diagram illustrating an example of frequency characteristics of capacitance of an electro-optical element of an optical voltage sensor that is determined to be non-defective in a temperature characteristic test.
FIG. 5 is an explanatory diagram illustrating an example of frequency characteristics of capacitance of an electro-optical element of an optical voltage sensor that is determined to be defective in a temperature characteristic test.
FIG. 6 is an explanatory diagram for explaining the operation of the optical voltage sensor.
FIG. 7 is a front view of an electro-optical element.
FIG. 8 is a plan view of an electro-optical element.
[Explanation of symbols]
9 External connection line, 20 Electro-optic element, 30 Impedance analyzer,
31 measuring terminals, 40 personal computers,
45 Pass / fail judgment reference data storage unit, 50 communication cable.

Claims

A first step of conducting a temperature characteristic test of an optical voltage sensor configured to measure a voltage using an electro-optical element and selecting a good optical voltage sensor;
The maximum value of the electrostatic capacity and the resonance frequency obtained from the frequency characteristics of the electrostatic capacity of the electro-optic element used in the non-defective photovoltage sensor selected in the first step are measured as the reference values for determining pass / fail. The second step,
And the frequency characteristics of the capacitance of the electro-optical element to be inspected, and the maximum capacitance value and the resonance frequency obtained from the measurement result are the maximum capacitance value and the resonance frequency obtained in the second step . A method for determining pass / fail of an electro-optical element, comprising a third step of determining that the electro-optical element to be inspected is a non-defective product if the value is near a reference value .

2. The electro-optical element pass / fail judgment method according to claim 1, wherein the maximum value of the electrostatic capacitance is set within a reference value ± 50% and the resonance frequency is set within a reference value ± 1% in the vicinity of the reference value. .

Performs temperature characteristic tests on photovoltage sensors configured to measure voltage using electro-optic elements, selects non-defective photovoltage sensors, and selects electro-optic elements used in the above-mentioned non-defective photovoltage sensors. A pass / fail judgment reference data storage unit that measures the frequency characteristics of the capacitance and stores the maximum value of the capacitance obtained from the obtained frequency characteristics of the capacitance and the resonance frequency as a reference value in advance,
The frequency characteristic of the capacitance of the electro-optical element to be inspected is measured, and the maximum capacitance value and the resonance frequency obtained from the measurement result are values in the vicinity of the reference value read from the pass / fail judgment reference data storage unit. An electro-optical element pass / fail discrimination apparatus, comprising: a pass / fail discrimination unit that discriminates that the electro-optical element to be inspected is a non-defective product.

4. The electro-optical element pass / fail discrimination apparatus according to claim 3, wherein the maximum value of the electrostatic capacitance is set within a reference value ± 50% and the resonance frequency is set within a reference value ± 1% in the vicinity of the reference value. .

An impedance analyzer to measure the frequency characteristic of the capacitance of the electro-optical element, according to claim 3 or claim 4, characterized in that it is composed of a personal computer having a quality decision reference data storage unit and a quality decision unit The electro-optical element quality determination device according to claim 1.

A first step of conducting a temperature characteristic test of an optical voltage sensor configured to measure a voltage using an electro-optical element and selecting a good optical voltage sensor;
The maximum value of the electrostatic capacity and the resonance frequency obtained from the frequency characteristics of the electrostatic capacity of the electro-optic element used in the non-defective optical voltage sensor selected in the first step are measured as the reference values for determining pass / fail. The second step,
And the frequency characteristic of the capacitance of the electro-optical element to be inspected, and the maximum capacitance value and the resonance frequency obtained from the measurement result are the maximum capacitance value and the resonance frequency obtained in the second step. If the value is in the vicinity of the reference value, the electro-optical element to be inspected includes a third step of determining that the electro-optical element is non-defective, and the electro-optical element determined to be non-defective in the third step is used. Manufacturing method of photovoltage sensor.

7. The method of manufacturing an optical voltage sensor according to claim 6, wherein, in the vicinity of the reference value, the maximum value of the electrostatic capacitance is set within a reference value ± 50% and the resonance frequency is set within a reference value ± 1%.