JP3731551B2 - Piezoelectric oscillator inspection system and inspection method thereof - Google Patents

Description

【００５２】
上記の式（１）で示された周波数偏差ｆ（ｎ）の傾きｆ′（ｎ）は、隣接する２つの測定点間の周波数偏差ｆ（ｎ＋１）及びｆ（ｎ）の差並びに温度ｔ（ｎ＋１）及びｔ（ｎ）の温度差との比で表わされる。即ち、単位温度当たりの周波数偏差の変化量を表わしている。
【００５３】
又、複数の上記した傾きに基づいた周波数偏差ｄｉｐ値［ｐｐｍ／℃］は、以下の式（２）で算出される。
【００５４】
【数２】

【００５５】
上記の式（２）は、図６に示すように、隣接する３つの傾きｆ′（ｎ），ｆ′（ｎ＋１），ｆ′（ｎ＋２）により表わされ、第１の周波数偏差の傾きｆ′（ｎ）と第３の周波数偏差の傾きｆ′（ｎ＋２）の平均値と第２の周波数偏差の傾きｆ′（ｎ＋１）との差の絶対値で表わされた周波数偏差である。又、図６に示すように、第１の傾きｆ′（ｎ）と第３の傾きｆ′（ｎ＋２）は、第２の傾きｆ′（ｎ＋１）の前後に位置する周波数偏差の傾きである。又、この式（２）から得られた周波数偏差ｄｉｐ値は、温度を可変し周波数偏差の変化を表した周波数温度特性の連続性を保証するもので、この値が小さければ連続性を、大きければ不連続であることを表わしている。
【００５６】
上記の式（１）の計算結果を１つ又はこれを２つ用いてその差により製品の良否を判定することもできる。一方、上記の式（２）は上記の式（１）の計算結果を３つ用いているが、これは、以下の理由によるものである。式（１）の計算結果を２つ用いた場合は、周波数偏差の変化が急激に変化する温度範囲において、その２つの傾きの差が大きくなりＤＩＰ現象と誤判定してしまうのを防止するためである。従って、上記の式（１）の計算結果を３つ用いることにより、周波数偏差の変化量が大きい温度範囲において、ＤＩＰ現象と誤判定してしまうことを防止することができる。
【００５７】
ここで、周波数測定に際して、前述した測定温度ステップをどの程度の間隔に定めるのが適切か、ＤＩＰ現象の検出の可能性との関係でその限界値（適性値）について言及する。図７は、その測定温度ステップとＤＩＰ現象の発生温度範囲で式（２）より得たｄｉｐ値との関係を示した図であり、実験データに基づいたグラフである。図７において、実際のＤＩＰ現象の発生温度範囲で一定の測定温度ステップ、即ち、１℃ステップから１℃毎に５℃ステップまでの条件で上記の式（２）で求めた周波数偏差ｄｉｐ値のうち、「◆」は最小値を、又「●」は最大値をプロットしたものである。尚、取り扱ったサンプルデータは、ＤＩＰ現象が発生し始める変化点からのピーク値が０．３ｐｐｍで、その温度幅が３℃のＤＩＰ現象を有する水晶発振器により得たものである。
【００５８】
図７によれば、２℃の測定温度ステップまでは、その最小値と最大値はほとんど変わらないが、それ以上の測定温度ステップになると急激にその差が拡大しているのが認められる。そして、今、製品の判定基準を０．１ｐｐｍ／℃とすれば測定温度ステップは３℃が限界であり、それ以上になるとＤＩＰ現象の検出が困難と判断できる。
【００５９】
引き続いて、図５を参照して、周波数偏差ｆ（ｎ）の傾きｆ′（ｎ）に基づいた周波数偏差ｄｉｐ値［ｐｐｍ／℃］を算出し、水晶発振器の良否を判定する手順（判定工程）について説明する。
【００６０】
図３に示す制御部２０内のマイクロプロセッサ２１は、図５の（Ａ）に示す計算開始を表わす計算番号ｎ＝０を指定し（ステップＳＴ７）、データ処理部２２を制御して、計算番号ｎ＝０に該当する周波数偏差ｆ（ｎ）の傾きｆ′（０）を、メモリ２３に格納されている周波数偏差ｆ（０），ｆ（１）及び測定温度ｔ（０），ｔ（１）を用いて上記した式（１）より算出し（ステップＳＴ８）、この値ｆ′（０）をメモリ２３に格納する。
【００６１】
そして、最後の周波数偏差ｆ（ｎ）の傾きｆ′（ｎ０−２）を算出したかどうか、即ち、計算番号ｎが最終番号（ｎ０−２）に達しているかどうかの判定を行う（ステップＳＴ９）。最終番号（ｎ０−２）に達していない場合（ステップＳＴ９ Ｎｏ）は、計算番号ｎを１だけ加算し（ステップＳＴ１０）周波数偏差の傾きを計算する工程（スッテプＳＴ８）に戻り、次の設定温度における周波数偏差ｆ（ｎ）の傾きｆ′（ｎ）を式（１）により算出する上述した手順を繰り返す（ステップＳＴ８〜ＳＴ１０）。最終番号（ｎ０−２）に達している場合（ステップＳＴ９ Ｙｅｓ）は、マイクロプロセッサ２１は周波数偏差ｆ（ｎ）の傾きｆ′（ｎ）の計算を終了する。
【００６２】
次に、図３に示すデータ処理部２２において、メモリ２３に格納されている３点の傾きｆ′（ｎ），ｆ′（ｎ＋１），ｆ′（ｎ＋２）に基づいた周波数偏差ｄｉｐ値［ｐｐｍ／℃］を計算番号ｎ＝０から１ステップ毎にｎ＝ｎ０−２までの値を用いて算出し（ステップＳＴ１１：第１及び第２の算出工程）、メモリ２３に格納する。マイクロプロセッサ２１は、算出したこれらすべてのｄｉｐ値［ｐｐｍ／℃］について所定の周波数偏差の規格値（判定基準）と比較し（比較工程）、この条件を満足しているかどうかを判定する（ステップＳＴ１２）。
【００６３】
マイクロプロセッサ２１は、所定の規格値と比較したすべての結果について満足していると判断した場合（ステップＳＴ１２ Ｙｅｓ）は、ＤＩＰ現象無しと判定し（ステップＳＴ１３）、その水晶発振器を良品とする。満足していない値が１つでも存在すると判断した場合（ステップＳＴ１２ Ｎｏ）はＤＩＰ現象有りと判定（ステップＳＴ１４）し、不良品とする。そして、次の水晶発振器を検査するため、図４に示す実測開始に戻り、上記した手順が繰り返される（ステップＳＴ１〜ステップＳＴ１４）。
【００６４】
（１−４） 第１の実施形態から得られる効果
以上説明した圧電発振器の検査システム及び検査方法によるＤＩＰ判定手順を用いた場合に得られる効果について説明する。
【００６５】
図８は、第１の実施形態によるＤＩＰ判定手順において、実測した周波数から得られた周波数偏差ｆ（ｎ）及び式（２）から算出した周波数偏差ｄｉｐ値を表わしたグラフである。
図８において、実線は周波数を実測して得られた周波数偏差ｆ（ｎ）を、又、点線は上記で示した式（２）で算出した周波数偏差ｄｉｐ値をプロットしたものである。このグラフは、ＡＴカット型水晶振動子を搭載した温度補償型水晶発振器の周波数温度特性を表わし、その実測値：実線が示すようにその曲線には凹凸がいくつか存在するのが見られる。
【００６６】
図８によれば、室温が３０℃〜４０℃の間でＤＩＰ現象と思われる現象が見られる。周波数温度特性の緩やかな温度範囲では、従来用いていた周波数温度特性を近似する近似式との差が０．１ｐｐｍ／℃程度のＤＩＰ現象の場合、近似計算誤差によるＤＩＰ現象の判別が困難である。しかしながら、図８に示す周波数偏差が緩やかな温度範囲において、本発明の式（２）による周波数偏差ｄｉｐ値は大きな不連続現象として表わされ、ＤＩＰ現象の有無の判断が微妙なＡＴカット型水晶振動子を搭載した温度補償型水晶発振器であっても、ＤＩＰ現象有りと明確に判定することができる。
【００６７】
一方、温度が７０℃〜１００℃の範囲で、周波数温度特性の変化量が大きくても、この式（２）から算出した周波数偏差ｄｉｐ値は±０．０５ｐｐｍ／℃以内にあり、周波数温度特性の連続性が保証されることになるので、この温度範囲ではＤＩＰ現象はないと明確に判定することができる。
【００６８】
以上、説明したように、第１の実施形態によれば、周波数偏差ｆ（ｎ）の傾きｆ′（ｎ）、そして、その測定点が隣接する３つの傾きｆ′（ｎ），ｆ′（ｎ＋１），ｆ′（ｎ＋２）を用いて、ｆ′（ｎ）とｆ′（ｎ＋２）の平均値とｆ′（ｎ＋１）との差、即ち、式（２）で算出した周波数偏差ｄｉｐ値を求め周波数温度特性の連続性からＤＩＰ現象の有無を判定するようにしたので、従来許容していた水晶発振器もＤＩＰ現象ありと容易にかつ正しく判定でき、その結果、ＤＩＰ現象の検出率をさらに高めることができるという効果が得られる。
【００６９】
又、第１の実施形態によれば、式（２）で算出した周波数偏差ｄｉｐ値を求め、周波数温度特性の連続性からＤＩＰ現象の有無を判断するようにしたので、数学上の２次，３次曲線等に近似できる周波数温度特性であっても、従来の判定基準としてきたこれらの近似式を求める必要がなくなる。
【００７０】
又、前述した数学上の曲線に近似できないような凹凸のある複雑な周波数温度特性、例えばＡＴカット型水晶振動子を搭載した温度補償型水晶発振器のような周波数温度特性において、ＤＩＰ現象なのかあるいは連続的に周波数偏差が変化しているのかを容易に判定できる。
【００７１】
又、従来の正確な周波数温度特性の測定のために温度を一定時間安定させる必要がなくなり、周波数温度特性の測定時間の大幅な短縮を図ることができるという効果が得られる。
【００７２】
さらに、第１の実施形態によれば、周波数偏差ｆ（ｎ）の傾きｆ′（ｎ）：式（１）及びこれを用いた周波数偏差ｄｉｐ値：式（２）は非常に簡単な計算式であり、それらを算出する時間が少なくてすむので、全体の測定時間にはほとんど影響を与えないという効果が得られる。
【００７３】
（２） 第２の実施形態
次に、本発明に係る第２の実施形態について説明する。
（２−１） 第２の実施形態における構成
まず、第２の実施形態における構成について説明する。
【００７４】
図９は、本発明の第２の実施形態による圧電発振器の検査システムの機能構成を示すブロック図である。図２と異なる点は、温度検出部７を除いた点にあり、他の機能ブロックについては同一であるのでその説明は省略する。又、第１の実施形態と同様に、圧電発振器としてＡＴカット型水晶振動子を搭載した水晶発振器を実施例として取り上げる。
【００７５】
（２−２） 第２の実施形態の原理
次に、第２の実施形態に係る原理について説明する。
【００７６】
本発明による第２の実施形態は、第１の実施形態における温度測定に代えて指定（又は、測定）時刻（所定の時点）と周波数偏差の変化量から式（２）により周波数偏差ｄｉｐ値を求めて、ＤＩＰ現象の有無を判定するというものである。この場合、測定時間の計時は図２に示すマイクロプロセッサ２１が行い、計時手段の役割を負う。
【００７７】
時間変化に対して温度変化が一定の関係を有していること、例えば直線的に、いわゆる正比例の関係で変化するように制御された気体により被測定物収納箱内の温度を設定する。この時間と温度の一定の関係（この場合、正比例の関係）があることを利用して、測定すべき温度範囲に相当する所定の測定時間範囲内で、設定した時間間隔で周波数を測定し、水晶発振器の周波数温度特性曲線を求める。この周波数温度特性曲線が第１の実施形態におけるものと異なる点は、温度に代えて時間軸で周波数偏差を表わした点にある。そして、求めたこの周波数温度特性を用い、式（１）から周波数偏差の傾きを得て、式（２）に基づく周波数偏差ｄｉｐ値を求めることでＤＩＰ現象の有無を判定するというものである。
【００７８】
尚、式（２）は、式（１）において温度ｔ（ｎ）を時刻Ｔ（ｎ）に置き換えることで、第１の実施形態と同様に扱うことができる。
【００７９】
（２−３） 第２の実施形態における動作
次に、動作について説明する。
【００８０】
図１０は、本発明の第２の実施形態における圧電発振器の検査システム１ｂにおいて、水晶発振器の検査手順（ＤＩＰ判定手順）を示すフローチャート図である。尚、既に説明した図５のローチャート図は、この第２の実施形態において、式（２）の周波数偏差ｄｉｐ値を求める場合にも使用される。
【００８１】
図１０に基づいて、制御部２０が行う周波数測定と周波数偏差を求める手順・動作について説明する。ここで、温度可変範囲を−３０℃〜９５℃までとした場合、温度と時間の関係が正比例の関係にあることを利用すると、この測定時間を、例えば、測定時間Ｔ０（例えば、１２０秒）を設定することで、その温度範囲における、時間軸をパラメータとする周波数温度特性曲線が得られる。尚、この測定時間Ｔ０は予め実験において検証された時間である。又、検査開始前において、本来求めるべき水晶発振器の周波数温度特性と第２の実施形態による測定方法で求めた周波数温度特性とのずれについて、水晶発振器の複数のサンプルにより測定して予め把握しておくものとする。
【００８２】
第１の実施形態と同様に、測定準備が終了すると、測定条件を入力した制御部２０は、図１に示す連続温調器３を動作させ、周波数の測定を開始するに当たり、低温側で、例えば、−３０℃において周波数が安定した時点を時間軸上で０とし、所定の高温、この場合９５℃に相当する測定時間Ｔ０（１２０秒）の間で周波数の測定を行う。尚、測定開始温度−３０℃に設定する手順については、第１の実施形態と同様である。
【００８３】
この周波数を測定する手順について、以下に、具体的に説明する。
【００８４】
まず、入力した測定数Ｎを指定し（ステップＳＴ２０）時間間隔Ｔ０／Ｎを求め、開始時の測定番号ｎ＝０を設定した後（ステップＳＴ２１）、この時間間隔（Ｔ０／Ｎ）×ｎ後における周波数を実測し周波数偏差ｆ（ｎ）を求め（ステップＳＴ２２）、この周波数偏差ｆ（ｎ）に対応する時刻Ｔ（ｎ）＝（Ｔ０／Ｎ）×ｎを設定する（ステップＳＴ２３）。そして、この時刻Ｔ（ｎ）の値が測定時間Ｔ０を超えているかどうかを判定し（ステップＳＴ２４）、測定時間Ｔ０を超えていない場合（ステップＳＴ２４，Ｎｏ）は測定番号ｎを１だけ加算して（ステップＳＴ２５）、上述した手順を繰り返す（ステップ２２〜ステップ２５）。又、超えている場合（ステップＳＴ２４，Ｙｅｓ）には、図５に示す、式（２）の周波数偏差ｄｉｐ値を求めるフローチャートへ移行する。
【００８５】
この場合、式（１）において第１の実施形態での測定温度ｔ（ｎ）を設定時刻Ｔ（ｎ）に置き換えればよく、計算手順に差異がないので図５に関する詳細な説明は省略する。
【００８６】
ここで、本発明による第２の実施形態において、前述した温度と時間の関係が所定の関係を維持していれば、被測定物収納箱５内の大きさ、測定すべき複数の水晶発振器の配置状態、連続温調器３から送付された気体の攪拌状態などに起因して、水晶発振器近傍の温度に遅れが発生しても良い。この場合、これに合わせて測定時間を設定することにより、必要とする規定の温度範囲を確保することができる。
【００８７】
また、温度と時間に関して所定の関係、この場合、正比例の関係にあるという前提で説明したが、これに関わらず、非線形の関係が混在していても良い。この場合、時間領域に応じてＤＩＰ現象の有無の判定基準を変えることで同様の手順で判定を行うことができる。
【００８８】
さらに、この第２の実施形態において、設定時刻Ｔ（ｎ）は、測定数Ｎと測定時間Ｔ０を予め指定して求めたが、制御部２０におけるタイマ機能を利用して実測した測定時刻（所定の時点）Ｔ（ｎ）を用いても良い。
【００８９】
（２−４） 第２の実施形態から得られる効果
次に、第２の実施形態で得られる効果について説明する。
【００９０】
この第２の実施形態から得られる効果は、上記した第１の実施形態と同じであり、さらに、以下に記載した効果が得られる。
【００９１】
図１１は、本発明の実施形態による周波数偏差を求めて得られたグラフであり、（ａ）は第２の実施形態による場合で設定時刻を、（ｂ）は第１の実施形態による場合で測定温度（この場合の測定温度ステップは２．５℃である。）をパラメータとした場合のそれぞれのグラフである。実線は、測定周波数から求めた周波数偏差であり、破線は数式（２）で算出した周波数偏差ｄｉｐ値である。尚、破線は計算値をさらに１０倍したものをグラフで表わしたものである。
【００９２】
この図１１から、（ａ）と（ｂ）のそれぞれのグラフにほぼ同一性が認められる。数式（２）で算出した周波数偏差ｄｉｐ値の設定時刻をパラメータとして、即ち、時間変化に対して温度の変化が直線的に変化することを利用して得られる、図１１（ａ）の破線で示したグラフによりＤＩＰ現象の有無を判定できるという効果が得られる。
【００９３】
又、温度と時間との所定の関係、及び所定の温度範囲を確保する測定時間を予め把握しておくので、直接温度を測定する必要がない。即ち、従来のように、被測定物収納箱内の温度が安定するまで待機する必要がないので、ＤＩＰ現象の検査工数を短縮することができ、水晶発振器の低コスト化が図れるという効果が得られる。
【００９４】
又、温度を測定する必要がないので温度検出部が不要となり、本発明の第２の実施形態における圧電発振器の検査システムが簡略化されるという効果が得られる。
【００９５】
又、この第２の実施形態における圧電発振器の検査システムでは、被測定物収納箱内の温度を可変させる温度範囲に相当する測定時間とこの範囲での測定数は、任意に設定することができる。この結果、その測定範囲において測定数を多く採ることで、測定時間間隔を細かくとることができ測定精度の向上を図ることができるという効果が得られる。
【００９６】
さらに、ＤＩＰ検査のみならず、通常の周波数温度特性が規格範囲以内か否かの検査にも、一定の条件下、例えば、設定温度の応答時間の遅れを考慮して測定時間範囲を任意に設定して、規格範囲以内か否かを判定することに、応用することができるという効果が得られる。
【００９７】
（３）変形例
上述した実施形態においては、周波数を実測して得られた周波数偏差ｆ（ｎ）の傾きｆ′（ｎ）、これに基づいた周波数偏差ｄｉｐ値を求めるこれらの式（１）及び式（２）は、圧電振動子としてＡＴカット型水晶振動子を搭載した水晶発振器を本発明に適用する場合について説明したが、本発明はこれに限定されない。即ち、連続する周波数温度特性を有する振動子、例えば、水晶振動子で言えば弾性表面波素子を用いた発振器や圧電振動子で言えばセラミック振動子やリチウムタンタレート、これらの圧電振動子を搭載した発振器や他の電子部品における不連続な周波数温度特性を持つという不良モードの検出に適用しても、同様の効果を得ることができる。
【００９８】
尚、圧電振動子を搭載した発振器に適用して説明したが、圧電振動子単独で上記した検査システム及びその検査方法として適用しても上記と同様の効果を奏する。
【００９９】
【発明の効果】
以上述べたように、本発明によれば、周波数を実測して得られた周波数偏差ｆ（ｎ）の傾きｆ′（ｎ）、そして、この隣接する３つの周波数偏差の傾きを使用し、周波数温度特性の連続性を保証するか否かの目安となる周波数偏差ｄｉｐ値を算出し、ＤＩＰ現象の有無を判定しているので、従来小さなＤＩＰ現象と許容していた水晶発振器もＤＩＰ現象ありと正確に判定できＤＩＰ現象の高い検出率を得ることができる。又、周波数偏差の変化量が大きい温度領域においてはＤＩＰ現象として誤判定することを防止できる。
【０１００】
又、上記した測定温度に代えて指定時刻（又は測定時刻）を設定し、周波数温度特性の連続性を保証するか否かの目安となる周波数偏差ｄｉｐ値を求めて、ＤＩＰ現象の有無を判定することにより、上記と同様の効果が得られる。又、温度を測定する必要がないので温度検出部が不要となり、圧電発振器の検査システムが簡略化されとともに、温度を安定させるという時間を必要としないので検査工数が短縮され、水晶発振器の低コスト化を図ることができる。
【図面の簡単な説明】
【図１】 本発明の第１の実施形態による圧電発振器の検査システムの概観構成を示す概観図である。
【図２】 本発明の第１の実施形態による圧電発振器の検査システムの機能構成を示すブロック図である。
【図３】 本発明の第１の実施形態による制御部の機能構成を示すブロック図である。
【図４】 本発明の第１の実施形態による圧電発振器の検査システムにおいて制御部が行う水晶発振器の検査（測定）手順を示すフローチャート図である。
【図５】 本発明の第１の実施形態による圧電発振器の検査システムにおいて制御部が行う水晶発振器の判定手順を示すフローチャート図である。
【図６】 周波数偏差ｆ（ｎ）の傾きｆ′（ｎ）及びこの複数の傾きに基づいた周波数偏差ｄｉｐ値を説明する図である。
【図７】 測定温度の測定ステップとＤＩＰ検出の関係を示した図である。
【図８】 本発明の第１の実施形態による圧電発振器の検査方法による計算式から求めた周波数偏差ｄｉｐ値を表わしたグラフである。
【図９】 本発明の第２の実施形態による圧電発振器の検査システムの機能構成を示すブロック図である。
【図１０】 本発明の第２の実施形態による圧電発振器の検査システムにおいて制御部が行う水晶発振器の検査手順を示すフローチャート図である。
【図１１】 本発明の第２の実施形態により得られたグラフで、（ａ）は第２の実施形態による場合で設定時刻を、（ｂ）は第１の実施形態による場合で測定温度をパラメータとした場合の周波数偏差の傾きに基づくグラフである。
【図１２】 水晶発振器特有の現象であるＤＩＰ現象を説明する図である。
【符号の説明】
１ １ａ，１ｂ 圧電発振器の検査システム
２ パーソナルコンピューター
２０ 制御部、 ２１ マイクロプロセッサ
２２ データ処理部 ２３ メモリ ２４ 入出力部
３ 連続温調器
４ 気体送風器
５ 被測定物収納箱
６ 温度検出部
７ 周波数測定部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inspection system and an inspection method for a piezoelectric oscillator, and in particular, in a crystal oscillator equipped with a piezoelectric resonator typified by an AT-cut type crystal resonator, discontinuity in frequency temperature characteristics, which is a phenomenon peculiar to this crystal oscillator. The present invention relates to a piezoelectric oscillator inspection system for detecting a phenomenon and an inspection method thereof.
[0002]
[Prior art]
At present, among the many crystal oscillators, the most versatile oscillator is a crystal oscillator using an AT-cut type crystal resonator, which is used as an oscillation source of a clock signal in a consumer communication device. In recent years, in particular, mobile phones have become widespread as consumer devices, and are used in various environments, for example, in a wide range from cold regions to tropical regions. Under such a wide range of environmental conditions, it is important that the frequency temperature characteristics of the crystal oscillator used in the mobile phone are good.
[0003]
Since the crystal resonators used in these crystal oscillators have a finite size, spurious vibrations exist in the vicinity of the frequency of the main vibration in addition to the vibration whose main vibration is the thickness-shear vibration. Therefore, when designing this crystal oscillator, the dimensions of the crystal resonator are taken into consideration within the size range in which the thickness shear vibration and its spurious vibration are not coupled, taking into account the size of the package that accommodates the crystal resonator. The machining accuracy range is determined.
[0004]
However, the main vibration and the spurious vibration are easily coupled due to processing variations of the AT-cut type crystal resonator and other factors, and a discontinuous phenomenon (hereinafter referred to as a DIP phenomenon) of the frequency temperature characteristic as shown in FIG. 12 occurs. . In addition, this DIP phenomenon has a different temperature depending on the AT-cut type crystal resonator produced, and adversely affects consumer communication equipment equipped with a crystal oscillator using the AT-cut type crystal resonator. For this reason, a DIP inspection for detecting the DIP phenomenon of this crystal oscillator is required.
[0005]
In this DIP inspection, a crystal oscillator is housed in a thermostat, a frequency temperature characteristic in a measurement temperature cycle is obtained, and the presence or absence of a DIP phenomenon is determined. As a method for determining the presence or absence of the DIP phenomenon, there has been a method of comparing with a mathematical formula that can be approximated to the actually measured frequency temperature characteristic (hereinafter referred to as an approximate formula). In this case, since it is necessary to obtain accurate frequency-temperature characteristics, frequency measurement was performed after the temperature in the thermostat was stabilized for a certain period of time. Then, it was determined that the DIP phenomenon exists when the difference between the value of the approximate expression described above and the value of the actually measured frequency temperature characteristic is 0.3 ppm / ° C. or more.
[0006]
[Problems to be solved by the invention]
As a standard of frequency temperature characteristics obtained by actually measuring this frequency, it is known that there is a standard of 0.3 ppm / ° C. as described above in an example of a mobile phone.
And even if a DIP phenomenon that satisfies this standard occurs, in the case of a crystal oscillator having a frequency temperature characteristic that is difficult to distinguish from the DIP phenomenon, for example, in a temperature region where the temperature change is large such as the high temperature side or the low temperature side, A small DIP phenomenon with a frequency deviation of about 0.1 ppm / ° C. expressed by the difference between an approximate expression value approximating the frequency temperature characteristic and an actual measurement value is allowed as an approximate calculation error and cannot be accurately determined as a DIP phenomenon. It was.
[0007]
In addition, in order to measure an accurate frequency temperature characteristic using an approximate expression approximating the frequency temperature characteristic, it is necessary to stabilize the temperature in the thermostat for a certain period of time, and this waiting time cannot be ignored. It was. In addition, in the case of a temperature compensated crystal oscillator using an AT-cut crystal resonator, the frequency temperature characteristic has many irregularities, so that it is difficult to obtain the approximate expression as described above, and the DIP phenomenon is accurately determined. There was a problem that it was not possible.
[0008]
The present invention has been made to solve the above-described problems, and a DIP having a small frequency deviation of about 0.1 ppm / ° C. expressed by a difference between an approximate expression value approximating a frequency temperature characteristic and an actual measurement value. It is an object of the present invention to obtain a piezoelectric oscillator inspection system and inspection method that can accurately detect even a phenomenon and can further improve quality as a high-precision product.
[0009]
Another object of the present invention is to obtain an inspection system and an inspection method for a piezoelectric oscillator that can eliminate a non-negligible waiting time for stabilizing the temperature in the thermostatic chamber for a certain time because of the necessity of comparing with the above-described approximate expression. Another object of the present invention is to provide a piezoelectric oscillator inspection system and inspection method that can accurately determine the DIP phenomenon in a temperature-compensated crystal oscillator having complicated frequency temperature characteristics and determine the quality.
[0010]
[Means for Solving the Problems]
The inspection system for a piezoelectric oscillator according to claim 1 is a piezoelectric oscillator inspection system for inspecting a frequency temperature characteristic indicating a change in frequency deviation indicating a deviation of a measurement frequency from a predetermined frequency by changing a temperature. A gas generating means for generating and blowing a temperature gas; a measured object storage means for storing the piezoelectric oscillator placed in the gas environment at the predetermined temperature; and a temperature detecting means for measuring and outputting the temperature of the piezoelectric oscillator. A frequency measuring means for measuring and outputting the frequency of the piezoelectric oscillator; and a judging means for judging the quality of the piezoelectric oscillator using a plurality of slopes of the frequency deviation within a predetermined temperature range of the frequency deviation. The means provides four or more predetermined temperatures within a temperature range for determining the quality of the piezoelectric oscillator, and sets three consecutive temperature intervals at the four predetermined temperatures. A first calculating means for calculating an average value of the slope of the frequency deviation in the first temperature interval and the slope of the frequency deviation in the third temperature interval; and between the first and third temperature intervals. A second calculating means for calculating a slope of the frequency deviation in the second temperature interval located, and an absolute value of a difference between the average value and the slope obtained by the second calculating means is compared with a predetermined standard value; And a comparison unit, wherein the piezoelectric oscillator is determined to be non-defective when the absolute value is smaller than the predetermined standard value within the temperature range.
[0011]
According to the above configuration, the frequency deviation is within a predetermined temperature range. In Since the judgment means for judging the quality of the piezoelectric oscillator using a plurality of frequency deviation slopes is provided, the frequency deviation expressed by the difference between the approximate expression value approximating the frequency temperature characteristic and the actual measurement value of the frequency deviation is 0. Even a discontinuous phenomenon as small as 1 ppm / ° C. can be accurately and easily determined as a DIP phenomenon, and the detection rate can be increased.
[0013]
In addition, according to the above configuration, the first calculation unit that calculates an average value of the slope of the frequency deviation in the first temperature interval and the slope of the frequency deviation in the third temperature interval, and the first and third A second calculating means for calculating the slope of the frequency deviation in the second temperature interval located between the temperature intervals, the average value obtained by the first calculating means, and the slope obtained by the second calculating means Comparing means for comparing the absolute value of the difference with a predetermined standard value, and when the absolute value is smaller than the predetermined standard value, the piezoelectric oscillator is judged as a non-defective product. In addition, it is possible to determine the presence or absence of the DIP phenomenon of the piezoelectric oscillator and to prevent erroneous determination of the presence or absence of the DIP phenomenon in a region where the amount of change is large.
[0014]
The inspection system for a piezoelectric oscillator according to claim 2 is a piezoelectric oscillator inspection system for inspecting a frequency temperature characteristic representing a change in frequency deviation indicating a deviation of a measurement frequency from a predetermined frequency by varying a temperature. A gas generating means for generating and blowing a gas at a predetermined temperature at a predetermined time, an object storage means for storing the piezoelectric oscillator placed in the gas environment at the predetermined temperature, and measuring and outputting the frequency of the piezoelectric oscillator And measuring means for determining the quality of the piezoelectric oscillator using slopes of a plurality of frequency deviations within a predetermined time range of the frequency deviation, wherein the determining means determines the quality of the piezoelectric oscillator. Four or more predetermined time points are provided in a time range corresponding to a temperature range to be performed, and the first time is set at three consecutive time intervals at the four predetermined time points. A first calculating means for calculating an average value of the slope of the frequency deviation in the time interval and the slope of the frequency deviation in the third time interval; and a second position located between the first and third time intervals. Second calculating means for calculating the slope of the frequency deviation in the time interval, and comparing means for comparing the absolute value of the difference between the average value and the slope obtained by the second calculating means with a predetermined standard value. The piezoelectric oscillator is determined to be non-defective when the absolute value is smaller than the predetermined standard value within the time range.
[0015]
According to the above configuration, the piezoelectric oscillator measures the frequency of the piezoelectric oscillator in a gas environment of a predetermined temperature blown at a predetermined time, and uses the obtained frequency deviations within a predetermined time range, and the plurality of frequency deviation gradients are used. Therefore, even a discontinuous phenomenon with a frequency deviation of about 0.1 ppm / ° C. expressed by the difference between the approximate expression value approximating the frequency temperature characteristic and the actual measurement value of the frequency deviation can be accurately and easily performed. This can be determined as a DIP phenomenon, and the detection rate can be further increased, and the piezoelectric oscillator inspection system can be simplified because no temperature measurement means for measuring temperature is required.
[0017]
In addition, according to the above configuration, the first calculating means for calculating an average value of the slope of the frequency deviation in the first time interval and the slope of the frequency deviation in the third time interval, and the first and third times A second calculation means for calculating a slope of the frequency deviation in the second time interval located between the intervals, an average value obtained by the first calculation means, and a slope obtained by the second calculation means; Comparing means for comparing the absolute value of the difference with a predetermined standard value, and when the absolute value is smaller than the predetermined standard value, the piezoelectric oscillator is judged as a non-defective product. In addition to being able to determine the presence or absence of the DIP phenomenon of the oscillator, it is possible to prevent erroneous determination of the presence or absence of the DIP phenomenon in a region where the amount of change is large.
[0018]
According to a third aspect of the present invention, there is provided a piezoelectric oscillator inspection system according to the first or second aspect, wherein the piezoelectric oscillator is a temperature-compensated crystal oscillator equipped with an AT-cut crystal resonator.
[0019]
The system is preferably applied to a temperature-compensated crystal oscillator equipped with an AT-cut crystal resonator whose frequency temperature characteristic may have a discontinuous phenomenon called a DIP phenomenon.
[0020]
The method for inspecting a piezoelectric oscillator according to claim 4, wherein the temperature is varied to inspect a frequency temperature characteristic representing a change in frequency deviation indicating a deviation of a measurement frequency from a predetermined frequency. A blowing step for generating and blowing a gas of temperature, a temperature measuring step for measuring the temperature of the piezoelectric oscillator, a frequency measuring step for measuring the frequency of the piezoelectric oscillator, and a plurality of frequencies within a predetermined temperature range of the frequency deviation A determination step of determining pass / fail of the piezoelectric oscillator using an inclination of deviation, wherein the determination step provides four or more predetermined temperatures within a temperature range for determining pass / fail of the piezoelectric oscillator, Calculate the average value of the slope of the frequency deviation in the first temperature interval and the slope of the frequency deviation in the third temperature interval at three consecutive temperature intervals at the predetermined temperature. A first calculation step, a second calculation step of calculating a slope of a frequency deviation in a second temperature interval located between the first and third temperature intervals, the average value and the second A comparison step of comparing an absolute value of a difference from the slope obtained in the calculation step with a predetermined standard value, and the piezoelectric oscillator is less than the predetermined standard value within the temperature range. Is determined to be non-defective.
[0021]
According to the above configuration, the frequency deviation is within a predetermined temperature range. In Since there is a determination step for determining the quality of the piezoelectric oscillator by using a plurality of frequency deviation slopes in the frequency deviation, a frequency deviation of 0.1 ppm / expressed by a difference between an approximate expression value approximating a frequency temperature characteristic and an actual measurement value is provided. Even a discontinuous phenomenon as small as about 0 ° C. can be accurately and easily determined as a DIP phenomenon, and the detection rate can be further increased.
[0023]
According to the above configuration, the first calculation step of calculating an average value of the slope of the frequency deviation in the first temperature interval and the slope of the frequency deviation in the third temperature interval, and the first and third temperatures A second calculation step of calculating a slope of a frequency deviation in a second temperature interval located between the intervals, an average value obtained by the first calculation step, and a slope obtained by the second calculation step A comparison step of comparing the absolute value of the difference with a predetermined standard value. If this absolute value is smaller than the predetermined standard value, the piezoelectric oscillator is judged as a non-defective product. In addition to being able to determine the presence or absence of the DIP phenomenon of the oscillator, it is possible to prevent erroneous determination of the presence or absence of the DIP phenomenon in a region where the amount of change is large.
[0024]
The method for inspecting a piezoelectric oscillator according to claim 5 is a method for inspecting a piezoelectric temperature oscillator in which a temperature is varied to inspect a frequency temperature characteristic representing a change in frequency deviation indicating a deviation in measurement frequency from a predetermined frequency. The piezoelectric oscillator using a blowing process for generating and blowing a gas at a predetermined temperature at a time point, a frequency measuring process for measuring the frequency of the piezoelectric oscillator, and a plurality of frequency deviation slopes within a predetermined time range of the frequency deviation And determining the quality of the piezoelectric oscillator, wherein the determining step provides four or more predetermined time points within a time range corresponding to a temperature range for determining the quality of the piezoelectric oscillator, and the four predetermined time points The average value of the slope of the frequency deviation in the first time interval and the slope of the frequency deviation in the third time interval is calculated at three consecutive time intervals in FIG. A first calculation step, a second calculation step for calculating a slope of a frequency deviation in a second time interval located between the first and third time intervals, and the average value and the second calculation step. A comparison step of comparing the absolute value of the difference from the slope obtained in step 1 with a predetermined standard value, and the piezoelectric oscillator is a non-defective product if the absolute value is smaller than the predetermined standard value within the time range. It is characterized by determining.
[0025]
According to the above configuration, the frequency of the piezoelectric oscillator in a gas environment of a predetermined temperature blown at a predetermined time point is measured, and the piezoelectric oscillator is measured using a plurality of frequency deviation slopes within a predetermined time range of the obtained frequency deviation. Since the quality is judged, even a discontinuous phenomenon having a frequency deviation as small as 0.1 ppm / ° C. expressed by the difference between the approximate expression value approximating the frequency temperature characteristic and the actual measurement value of the frequency deviation can be accurately and easily performed. It can be determined as a phenomenon, and the detection rate can be further increased, and the piezoelectric oscillator inspection method can be simplified because it does not require a temperature measurement step for measuring temperature.
[0027]
Further, according to the above configuration, the first calculation step of calculating the average value of the slope of the frequency deviation in the first time interval and the slope of the frequency deviation in the third time interval, and the first and third times A second calculation step of calculating a slope of a frequency deviation in a second time interval located between the intervals, an average value obtained by the first calculation step, and a slope obtained by the second calculation step A comparison step of comparing the absolute value of the difference with a predetermined standard value. If this absolute value is smaller than the predetermined standard value, the piezoelectric oscillator is judged as a non-defective product. In addition to being able to determine the presence or absence of the DIP phenomenon of the oscillator, it is possible to prevent erroneous determination of the presence or absence of the DIP phenomenon in a region where the amount of change is large.
[0028]
According to a sixth aspect of the present invention, there is provided a method for inspecting a piezoelectric oscillator according to the fourth or fifth aspect, wherein the piezoelectric oscillator is a temperature compensated crystal oscillator on which an AT-cut crystal resonator is mounted.
[0029]
The inspection method is preferably applied to a temperature-compensated crystal oscillator equipped with an AT-cut crystal resonator whose frequency temperature characteristic may have a discontinuous phenomenon called a DIP phenomenon.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
(1) First embodiment
(1-1) Principle of the first embodiment
First, the principle according to the first embodiment will be described.
[0031]
According to the first embodiment of the present invention, the DIP phenomenon is based on the result obtained by comparing the frequency deviation calculated based on the slopes of a plurality of frequency deviations within a predetermined temperature range with the standard value of the predetermined frequency deviation. It is determined whether the crystal oscillator is good or bad. That is, when a frequency deviation based on a plurality of frequency deviations, specifically, a frequency deviation based on three consecutive inclinations is equal to or less than the above-mentioned standard value within a predetermined temperature range, the measured frequency temperature characteristic has continuity. This crystal oscillator is based on the fact that it can be determined that there is no DIP phenomenon.
[0032]
(1-2) Configuration of the first embodiment
FIG. 1 is a diagram illustrating an overview of a piezoelectric oscillator inspection system 1 according to the first embodiment, and FIG. 2 is a block diagram illustrating functions of the inspection system.
[0033]
In the first embodiment, a crystal oscillator on which an AT-cut type crystal resonator is mounted as a piezoelectric oscillator will be described as an example.
[0034]
In FIG. 1, a piezoelectric oscillator inspection system 1 according to the first embodiment of the present invention includes a personal computer 2, a continuous temperature controller 3, a gas blower 4, a measured object storage box 5, a temperature detector 6, a frequency. It consists of a measuring unit 7.
[0035]
FIG. 2 is a functional block diagram clarifying the connections and input / output signals between the components in FIG. 1 is the same as FIG. 1 except that the personal computer 2 of FIG. 1 is replaced with a control unit 20 that is a functional name.
[0036]
In FIG. 2, the piezoelectric oscillator inspection system 1 a according to the first embodiment includes a control unit 20 (determination means) that controls the entire piezoelectric oscillator inspection system 1 a, and a temperature cycle range specified by the control of the control unit 20. Continuous temperature controller 3 (gas generating means) for generating gas, gas blower 4 (gas generating means) for blowing the gas generated by continuous temperature controller 3, and environment blown by gas blower 4 A measurement object storage box 5 (measurement object storage means) that accommodates a plurality of crystal oscillators placed on the substrate, and controls the control unit 20 to measure the frequency of the crystal oscillator stored in the measurement object storage box 5. The frequency measuring unit 6 (frequency measuring means) that outputs the temperature, the temperature around the crystal oscillator housed in the measured object storage box 5 is measured by the temperature sensor, and the temperature detecting unit 7 (temperature detecting means) that outputs this measured value ), Nominal The deviation of the measured frequency of the wave number (a predetermined frequency) Representation The control unit 20 is configured to determine the quality of the crystal oscillator based on the slope of the frequency deviation.
[0037]
FIG. 3 is a block diagram illustrating a functional configuration of the control unit 20 typified by the personal computer 2.
[0038]
In FIG. 3, the control unit 20 obtains the gradient of the frequency deviation based on the microprocessor 21 that controls the entire functional block in the control unit 20, calculates the frequency deviation based on these three gradients, and calculates the calculated frequency deviation. And a data processing unit 22 (first and second calculation means, comparison means) for comparing the predetermined frequency deviation with a standard value of a predetermined frequency deviation, the frequency deviation of the crystal oscillator at the measured ambient temperature, and this frequency deviation And a memory 23 for storing a frequency deviation calculated by using a plurality of these inclinations, frequency measurement data from the frequency measurement unit 6, actual temperature data from the temperature detection unit 7, and control signals from the microprocessor 21 And the like, and a data bus 25 for connecting these blocks to each other.
[0039]
(1-3) Operation in the first embodiment
Next, the operation and inspection procedure of the piezoelectric oscillator inspection system according to the first embodiment will be described.
[0040]
4 and 5 are flowcharts showing a crystal oscillator inspection procedure (DIP determination procedure) performed by the control unit 20 in the piezoelectric oscillator inspection system 1a according to the first embodiment.
[0041]
Based on FIG. 2 thru | or FIG. 4, the operation | movement which calculates | requires the measurement of the frequency performed by control of the control part 20, and a frequency deviation first is demonstrated. Here, it is assumed that the inspection of the frequency deviation is performed from −35 ° C. to 100 ° C. In the description, the measurement temperature cycle range is assumed to be −35 ° C. to 100 ° C., but is not limited to this range and can be freely set.
[0042]
When measuring the frequency, a gas of −35 ° C. is generated and blown into the measured object storage box 5 to maintain and stabilize this temperature state for a certain period of time. In the step, a temperature environment to be measured in the measured object storage box 5 is created. Then, the frequency is measured at every predetermined temperature step from −35 ° C. For the sake of explanation, the measurement is dealt with when starting from the low temperature side, but it may be performed from either the low temperature side or the high temperature side. Moreover, although inert gas, such as air or nitrogen, can be used for gas, it must be stable gas in the measurement temperature range.
[0043]
Further, in order to accurately detect the DIP phenomenon, the predetermined temperature measurement step needs to be an appropriate value, and details thereof will be described later. The number of measurements n0 is set from the measurement temperature range and the temperature measurement step.
[0044]
At the start of measurement, the internal temperature of the measurement object storage box 5 is kept below the measurement start temperature. In this case, since the measurement start temperature is −35 ° C., it is desirable to set it to −40 ° C. or lower.
[0045]
Next, the mass production substrate on which the crystal oscillator is mounted is accommodated in the measurement object storage box 5, and measurement conditions such as a temperature cycle range are input to the personal computer 2. The control unit 20 that has input the measurement conditions sets the measurement start number n = 0 (step ST1) and sets the temperature in the object storage box 5 as the set temperature t (0) = in order to operate the continuous temperature controller 3. Specify -35 ° C. Then, the continuous temperature controller 3 sets the gas temperature, the air volume, and the like that become the temperature t (0) in the designated first object storage box 5 (Step ST2), and generates the gas at the designated temperature. Then, the gas is blown through the gas blower 4 to the measured object storage box 5 (blower process).
[0046]
The control unit 20 inputs the measured value of the ambient temperature of the crystal oscillator measured by the temperature sensor from the temperature detection unit 6 via the input / output unit 24 (temperature measurement process), and whether or not the set temperature t (0) has been reached. Determine (step ST3). When the set temperature t (0) has not been reached (No in step ST3), the control unit 20 controls the continuous temperature controller 3 again with respect to the gas temperature, air volume, etc. so as to reach the set temperature (return to step ST2). .
[0047]
When the set temperature t (0) is reached (step ST3 Yes), the control unit 20 inputs the actually measured frequency from the frequency measurement unit 7 via the input / output unit 24 shown in FIG. 3 (frequency measurement). Step), the frequency deviation f (0) is obtained and stored in the memory 23 together with the set temperature t (0) (step ST4). Further, it is determined whether the set temperature is the final measured temperature t (n) = 100 ° C. and the corresponding measurement number n = n0-1 (step ST5). When the final measurement number n is not n0-1 (No in step ST5), the control unit 20 adds 1 to the measurement number n (step ST6) and returns to the temperature setting t (n) (step ST2). The temperature t (n + 1) of the next measurement temperature is set at an appropriate measurement temperature step which will be described later and which is higher than the next temperature t (n) corresponding to the measurement number, and the above-described procedure is repeated (steps ST2 to ST2). ST6).
[0048]
When the final measurement number n = n0-1 (Yes in step ST5), the frequency measurement is finished, and the slope f ′ (n) of the frequency deviation f (n) obtained from the measured frequency and the plurality of these are measured. A frequency deviation dip value [ppm / ° C.] based on the slope is obtained by a calculation formula described later.
[0049]
Here, with reference to FIG. 6 and the formula, the calculation formula for obtaining the above-described slope f ′ (n) of the frequency deviation f (n) and the frequency deviation dip value [ppm / ° C.] based on the plurality of slopes will be described. To do.
[0050]
The slope f ′ (n) of the frequency deviation f (n) is calculated by the following equation (1).
[0051]
[Expression 1]

[0052]
The slope f ′ (n) of the frequency deviation f (n) shown in the above equation (1) is the difference between the frequency deviations f (n + 1) and f (n) between two adjacent measurement points and the temperature t ( n + 1) and the temperature difference between t (n). That is, it represents the amount of change in frequency deviation per unit temperature.
[0053]
Further, the frequency deviation dip value [ppm / ° C.] based on a plurality of the above-described inclinations is calculated by the following equation (2).
[0054]
[Expression 2]

[0055]
As shown in FIG. 6, the above equation (2) is represented by three adjacent gradients f ′ (n), f ′ (n + 1), f ′ (n + 2), and the first frequency deviation gradient f. '(N) is a frequency deviation represented by the absolute value of the difference between the average value of the slope f' (n + 2) of the third frequency deviation and the slope f '(n + 1) of the second frequency deviation. As shown in FIG. 6, the first gradient f ′ (n) and the third gradient f ′ (n + 2) are gradients of frequency deviations located before and after the second gradient f ′ (n + 1). . Also, the frequency deviation dip value obtained from this equation (2) guarantees the continuity of the frequency-temperature characteristic that represents the change in the frequency deviation by varying the temperature. If this value is small, the continuity can be increased. Is discontinuous.
[0056]
It is also possible to determine the quality of the product based on the difference between one or two calculation results of the above formula (1). On the other hand, the above equation (2) uses three calculation results of the above equation (1) for the following reason. When two calculation results of the formula (1) are used, in order to prevent the difference between the two slopes from becoming large in the temperature range where the change in the frequency deviation changes abruptly, it is erroneously determined as the DIP phenomenon. It is. Therefore, by using three calculation results of the above formula (1), it is possible to prevent erroneous determination as a DIP phenomenon in a temperature range in which the amount of change in frequency deviation is large.
[0057]
Here, in the frequency measurement, what is the appropriate interval between the above-described measurement temperature steps, the limit value (appropriate value) will be mentioned in relation to the possibility of detecting the DIP phenomenon. FIG. 7 is a graph showing the relationship between the measured temperature step and the dip value obtained from Equation (2) in the temperature range where the DIP phenomenon occurs, and is a graph based on experimental data. In FIG. 7, the frequency deviation dip value obtained by the above equation (2) under the condition of a constant measurement temperature step in the actual temperature range where the DIP phenomenon occurs, that is, from 1 ° C. step to 5 ° C. step every 1 ° C. Of these, “♦” is a minimum value, and “●” is a maximum value. The sample data handled was obtained by a crystal oscillator having a DIP phenomenon having a peak value of 0.3 ppm from a change point at which the DIP phenomenon starts to occur and a temperature range of 3 ° C.
[0058]
According to FIG. 7, the minimum value and the maximum value hardly change until the measurement temperature step of 2 ° C., but it is recognized that the difference rapidly increases when the measurement temperature step is higher than that. Now, if the product criterion is 0.1 ppm / ° C., the limit of the measurement temperature step is 3 ° C., and if it exceeds that, it can be judged that the DIP phenomenon is difficult to detect.
[0059]
Subsequently, referring to FIG. 5, a procedure for determining the quality of the crystal oscillator by calculating the frequency deviation dip value [ppm / ° C.] based on the slope f ′ (n) of the frequency deviation f (n) (determination step). ).
[0060]
The microprocessor 21 in the control unit 20 shown in FIG. 3 designates the calculation number n = 0 indicating the calculation start shown in FIG. 5A (step ST7), and controls the data processing unit 22 to calculate the calculation number. The gradient f ′ (0) of the frequency deviation f (n) corresponding to n = 0 is determined from the frequency deviations f (0) and f (1) stored in the memory 23 and the measured temperatures t (0) and t (1 ) Using the above equation (1) (step ST8), and this value f '(0) is stored in the memory 23.
[0061]
Then, it is determined whether or not the slope f ′ (n0-2) of the last frequency deviation f (n) has been calculated, that is, whether the calculation number n has reached the final number (n0-2) (step ST9). ). If the final number (n0-2) has not been reached (No in step ST9), the calculation number n is incremented by 1 (step ST10), and the process returns to the step of calculating the slope of the frequency deviation (step ST8). The above-described procedure for calculating the slope f ′ (n) of the frequency deviation f (n) at (1) is repeated (steps ST8 to ST10). When the final number (n0-2) has been reached (step ST9 Yes), the microprocessor 21 ends the calculation of the slope f ′ (n) of the frequency deviation f (n).
[0062]
Next, in the data processing unit 22 shown in FIG. 3, the frequency deviation dip value [ppm based on the gradients f ′ (n), f ′ (n + 1), f ′ (n + 2) at the three points stored in the memory 23. / ° C.] is calculated using the values from calculation number n = 0 to n = n0-2 for each step (step ST11: first and second calculation steps) and stored in the memory 23. The microprocessor 21 compares all the calculated dip values [ppm / ° C.] with a standard value (determination standard) of a predetermined frequency deviation (comparison step), and determines whether or not this condition is satisfied (step) ST12).
[0063]
When the microprocessor 21 determines that all the results compared with the predetermined standard value are satisfied (Yes in step ST12), it determines that there is no DIP phenomenon (step ST13), and makes the crystal oscillator non-defective. If it is determined that there is even one unsatisfied value (No in step ST12), it is determined that there is a DIP phenomenon (step ST14), and a defective product is determined. And in order to test | inspect the next crystal oscillator, it returns to the measurement start shown in FIG. 4, and the above-mentioned procedure is repeated (step ST1-step ST14).
[0064]
(1-4) Effects obtained from the first embodiment
The effects obtained when the DIP determination procedure using the piezoelectric oscillator inspection system and inspection method described above are described.
[0065]
FIG. 8 is a graph showing the frequency deviation dip value calculated from the frequency deviation f (n) obtained from the actually measured frequency and the equation (2) in the DIP determination procedure according to the first embodiment.
In FIG. 8, the solid line plots the frequency deviation f (n) obtained by actually measuring the frequency, and the dotted line plots the frequency deviation dip value calculated by the equation (2) shown above. This graph shows the frequency-temperature characteristics of a temperature compensated crystal oscillator equipped with an AT-cut crystal resonator. As shown by the actual measurement value: solid line, there are some irregularities in the curve.
[0066]
According to FIG. 8, a phenomenon that seems to be a DIP phenomenon is observed when the room temperature is between 30 ° C. and 40 ° C. In the temperature range where the frequency temperature characteristic is moderate, it is difficult to discriminate the DIP phenomenon due to the approximation calculation error in the case of the DIP phenomenon whose difference from the approximate expression approximating the frequency temperature characteristic used in the past is about 0.1 ppm / ° C. . However, in the temperature range where the frequency deviation is moderate as shown in FIG. 8, the frequency deviation dip value according to the equation (2) of the present invention is expressed as a large discontinuous phenomenon, and the presence or absence of the DIP phenomenon is delicately determined. Even with a temperature-compensated crystal oscillator equipped with a vibrator, it can be clearly determined that there is a DIP phenomenon.
[0067]
On the other hand, the frequency deviation dip value calculated from the equation (2) is within ± 0.05 ppm / ° C. even when the temperature is in the range of 70 ° C. to 100 ° C. and the change amount of the frequency temperature characteristic is large. Therefore, it can be clearly determined that there is no DIP phenomenon in this temperature range.
[0068]
As described above, according to the first embodiment, the slope f ′ (n) of the frequency deviation f (n) and the three slopes f ′ (n), f ′ ( n + 1) and f ′ (n + 2) are used to calculate the difference between the average value of f ′ (n) and f ′ (n + 2) and f ′ (n + 1), that is, the frequency deviation dip value calculated by equation (2). Since the presence or absence of the DIP phenomenon is determined from the continuity of the required frequency temperature characteristics, the crystal oscillator that has been allowed in the past can be easily and correctly determined as having the DIP phenomenon. As a result, the detection rate of the DIP phenomenon is further increased. The effect that it can be obtained.
[0069]
Further, according to the first embodiment, the frequency deviation dip value calculated by the equation (2) is obtained, and the presence or absence of the DIP phenomenon is determined from the continuity of the frequency temperature characteristic. Even if the frequency-temperature characteristic can be approximated to a cubic curve or the like, it is not necessary to obtain these approximate expressions that have been used as the conventional criterion.
[0070]
Also, in the complex frequency temperature characteristics with irregularities that cannot be approximated by the mathematical curve described above, for example, the frequency temperature characteristics of a temperature compensated crystal oscillator equipped with an AT cut type crystal resonator, the DIP phenomenon or It can be easily determined whether the frequency deviation continuously changes.
[0071]
Further, there is no need to stabilize the temperature for a certain period of time for the conventional accurate measurement of the frequency temperature characteristic, and the effect that the measurement time of the frequency temperature characteristic can be greatly shortened can be obtained.
[0072]
Furthermore, according to the first embodiment, the slope f ′ (n) of the frequency deviation f (n): Equation (1) and the frequency deviation dip value using the equation (1) are very simple calculation formulas. Since it takes less time to calculate them, there is an effect that the entire measurement time is hardly affected.
[0073]
(2) Second embodiment
Next, a second embodiment according to the present invention will be described.
(2-1) Configuration in the second embodiment
First, the configuration in the second embodiment will be described.
[0074]
FIG. 9 is a block diagram showing a functional configuration of a piezoelectric oscillator inspection system according to the second embodiment of the present invention. The difference from FIG. 2 is that the temperature detecting unit 7 is excluded, and the other functional blocks are the same, and the description thereof is omitted. Similarly to the first embodiment, a crystal oscillator equipped with an AT-cut crystal resonator as a piezoelectric oscillator will be taken as an example.
[0075]
(2-2) Principle of the second embodiment
Next, the principle according to the second embodiment will be described.
[0076]
In the second embodiment of the present invention, instead of the temperature measurement in the first embodiment, the frequency deviation dip value is calculated by the equation (2) from the designated (or measurement) time (predetermined time) and the amount of change in the frequency deviation. In other words, the presence or absence of the DIP phenomenon is determined. In this case, the measurement time is measured by the microprocessor 21 shown in FIG. 2 and serves as a time measuring means.
[0077]
The temperature in the measured object storage box is set by the gas controlled so that the temperature change has a certain relationship with respect to the time change, for example, linearly changes in a so-called direct proportional relationship. Using this constant relationship between time and temperature (in this case, a direct proportional relationship), the frequency is measured at a set time interval within a predetermined measurement time range corresponding to the temperature range to be measured. Obtain the frequency-temperature characteristic curve of the crystal oscillator. The frequency temperature characteristic curve is different from that in the first embodiment in that the frequency deviation is represented on the time axis instead of the temperature. Then, using this obtained frequency temperature characteristic, the slope of the frequency deviation is obtained from the equation (1), and the presence or absence of the DIP phenomenon is determined by obtaining the frequency deviation dip value based on the equation (2).
[0078]
Equation (2) can be handled in the same manner as in the first embodiment by replacing temperature t (n) with time T (n) in equation (1).
[0079]
(2-3) Operation in the second embodiment
Next, the operation will be described.
[0080]
FIG. 10 is a flowchart showing a crystal oscillator inspection procedure (DIP determination procedure) in the piezoelectric oscillator inspection system 1b according to the second embodiment of the present invention. The already described flowchart of FIG. 5 is also used when the frequency deviation dip value of equation (2) is obtained in the second embodiment.
[0081]
Based on FIG. 10, the procedure and operation | movement which calculates the frequency measurement and frequency deviation which the control part 20 performs are demonstrated. Here, when the temperature variable range is set to −30 ° C. to 95 ° C., using the fact that the relationship between the temperature and the time is directly proportional, this measurement time is, for example, the measurement time T0 (for example, 120 seconds). Is set, a frequency-temperature characteristic curve using the time axis as a parameter in the temperature range is obtained. The measurement time T0 is a time verified in advance in an experiment. In addition, before the start of the inspection, the deviation between the frequency temperature characteristic of the crystal oscillator that should originally be obtained and the frequency temperature characteristic obtained by the measurement method according to the second embodiment is measured and measured in advance using a plurality of samples of the crystal oscillator. I shall keep it.
[0082]
As in the first embodiment, when the measurement preparation is completed, the control unit 20 that has input the measurement conditions operates the continuous temperature controller 3 illustrated in FIG. 1 to start frequency measurement. For example, the time when the frequency is stabilized at −30 ° C. is set to 0 on the time axis, and the frequency is measured during a measurement time T0 (120 seconds) corresponding to a predetermined high temperature, in this case, 95 ° C. The procedure for setting the measurement start temperature to −30 ° C. is the same as in the first embodiment.
[0083]
The procedure for measuring this frequency will be specifically described below.
[0084]
First, the input number of measurements N is designated (step ST20), the time interval T0 / N is obtained, the measurement number n = 0 at the start is set (step ST21), and this time interval (T0 / N) × n later The frequency deviation f (n) is obtained by actually measuring the frequency at (step ST22), and time T (n) = (T0 / N) × n corresponding to the frequency deviation f (n) is set (step ST23). Then, it is determined whether or not the value of the time T (n) exceeds the measurement time T0 (step ST24). If the measurement time T0 is not exceeded (step ST24, No), the measurement number n is incremented by 1. (Step ST25), the above-described procedure is repeated (step 22 to step 25). On the other hand (step ST24, Yes), the process proceeds to the flowchart for obtaining the frequency deviation dip value of equation (2) shown in FIG.
[0085]
In this case, in the equation (1), the measured temperature t (n) in the first embodiment may be replaced with the set time T (n), and since there is no difference in the calculation procedure, detailed description regarding FIG. 5 is omitted.
[0086]
Here, in the second embodiment according to the present invention, if the relationship between the temperature and the time described above maintains a predetermined relationship, the size of the measured object storage box 5 and the plurality of crystal oscillators to be measured are measured. A delay may occur in the temperature in the vicinity of the crystal oscillator due to the arrangement state, the stirring state of the gas sent from the continuous temperature controller 3, and the like. In this case, the required temperature range can be secured by setting the measurement time according to this.
[0087]
Further, the description has been made on the assumption that there is a predetermined relationship with respect to temperature and time, in this case, a direct proportional relationship, but a non-linear relationship may be mixed regardless of this. In this case, the determination can be performed in the same procedure by changing the determination criterion of the presence or absence of the DIP phenomenon according to the time domain.
[0088]
Furthermore, in the second embodiment, the set time T (n) is obtained by designating the number of measurements N and the measurement time T0 in advance, but the measurement time (predetermined by using the timer function in the control unit 20). ) T (n) may be used.
[0089]
(2-4) Effects obtained from the second embodiment
Next, effects obtained in the second embodiment will be described.
[0090]
The effects obtained from the second embodiment are the same as those of the first embodiment described above, and further the effects described below can be obtained.
[0091]
FIG. 11 is a graph obtained by calculating the frequency deviation according to the embodiment of the present invention, where (a) is a case according to the second embodiment and (b) is a case according to the first embodiment. It is each graph at the time of using measurement temperature (measurement temperature step in this case is 2.5 degreeC) as a parameter. The solid line is the frequency deviation obtained from the measured frequency, and the broken line is the frequency deviation dip value calculated by Equation (2). The broken line represents a graph obtained by further multiplying the calculated value by 10.
[0092]
From FIG. 11, almost the same is recognized in the graphs of (a) and (b). A broken line in FIG. 11A is obtained using the set time of the frequency deviation dip value calculated by Equation (2) as a parameter, that is, using the fact that the temperature change linearly changes with time. The effect that the presence or absence of the DIP phenomenon can be determined from the graph shown is obtained.
[0093]
In addition, since the predetermined relationship between temperature and time and the measurement time for securing the predetermined temperature range are known in advance, it is not necessary to directly measure the temperature. In other words, unlike the conventional case, there is no need to wait until the temperature in the measured object storage box stabilizes, so that the number of inspection steps for the DIP phenomenon can be shortened and the cost of the crystal oscillator can be reduced. It is done.
[0094]
In addition, since there is no need to measure the temperature, the temperature detector is not required, and the piezoelectric oscillator inspection system according to the second embodiment of the present invention can be simplified.
[0095]
In the piezoelectric oscillator inspection system according to the second embodiment, the measurement time corresponding to the temperature range in which the temperature in the object storage box can be varied and the number of measurements in this range can be arbitrarily set. . As a result, by taking a large number of measurements in the measurement range, it is possible to obtain an effect that the measurement time interval can be made fine and the measurement accuracy can be improved.
[0096]
Furthermore, not only for DIP inspection but also for inspection of whether or not the normal frequency temperature characteristics are within the specified range, the measurement time range is arbitrarily set under certain conditions, for example, taking into account the delay of the set temperature response time Thus, it is possible to obtain an effect that it can be applied to determine whether or not it is within the standard range.
[0097]
(3) Modification
In the embodiment described above, the slope f ′ (n) of the frequency deviation f (n) obtained by actually measuring the frequency, and these formulas (1) and (2) for obtaining the frequency deviation dip value based on the slope f ′ (n). Has described the case where a crystal oscillator mounting an AT-cut type crystal resonator as a piezoelectric resonator is applied to the present invention, but the present invention is not limited to this. That is, a vibrator having continuous frequency temperature characteristics, for example, an oscillator using a surface acoustic wave element for a crystal vibrator or a ceramic vibrator or a lithium tantalate for a piezoelectric vibrator, and these piezoelectric vibrators are mounted. The same effect can be obtained even if it is applied to the detection of a defective mode having a discontinuous frequency temperature characteristic in the oscillator and other electronic components.
[0098]
Although the description has been made by applying the present invention to an oscillator equipped with a piezoelectric vibrator, the same effects as described above can be obtained even if the piezoelectric vibrator alone is applied as the inspection system and the inspection method thereof.
[0099]
【The invention's effect】
As described above, according to the present invention, the frequency f (n) slope f ′ (n) obtained by actually measuring the frequency and the slopes of the three adjacent frequency deviations are used to determine the frequency. Since the frequency deviation dip value, which is a measure of whether or not to guarantee the continuity of the temperature characteristics, is calculated and the presence or absence of the DIP phenomenon is determined, the crystal oscillator that has been allowed to be a small DIP phenomenon is also considered to have a DIP phenomenon. Accurate determination is possible, and a high detection rate of the DIP phenomenon can be obtained. Further, it is possible to prevent erroneous determination as a DIP phenomenon in a temperature region where the amount of change in frequency deviation is large.
[0100]
In addition, a specified time (or measurement time) is set instead of the above-described measurement temperature, and a frequency deviation dip value is obtained as a guideline for whether or not the continuity of the frequency temperature characteristic is guaranteed, and the presence or absence of the DIP phenomenon is determined. By doing so, the same effect as described above can be obtained. In addition, since there is no need to measure the temperature, the temperature detector is not required, the piezoelectric oscillator inspection system is simplified, and the time required to stabilize the temperature is not required, so the inspection man-hours are reduced and the cost of the crystal oscillator is reduced. Can be achieved.
[Brief description of the drawings]
FIG. 1 is an overview diagram showing an overview configuration of a piezoelectric oscillator inspection system according to a first embodiment of the present invention.
FIG. 2 is a block diagram showing a functional configuration of a piezoelectric oscillator inspection system according to the first embodiment of the present invention.
FIG. 3 is a block diagram showing a functional configuration of a control unit according to the first embodiment of the present invention.
FIG. 4 is a flowchart showing a crystal oscillator inspection (measurement) procedure performed by a control unit in the piezoelectric oscillator inspection system according to the first embodiment of the present invention;
FIG. 5 is a flowchart showing a crystal oscillator determination procedure performed by a control unit in the piezoelectric oscillator inspection system according to the first embodiment of the present invention.
FIG. 6 is a diagram for explaining a slope f ′ (n) of a frequency deviation f (n) and a frequency deviation dip value based on the plurality of slopes.
FIG. 7 is a diagram showing a relationship between a measurement step of measurement temperature and DIP detection.
FIG. 8 is a graph showing a frequency deviation dip value obtained from a calculation formula according to the piezoelectric oscillator inspection method according to the first embodiment of the present invention.
FIG. 9 is a block diagram showing a functional configuration of an inspection system for a piezoelectric oscillator according to a second embodiment of the present invention.
FIG. 10 is a flowchart showing a crystal oscillator inspection procedure performed by a control unit in the piezoelectric oscillator inspection system according to the second embodiment of the present invention.
11A and 11B are graphs obtained by the second embodiment of the present invention, in which FIG. 11A shows the set time in the case of the second embodiment, and FIG. 11B shows the measured temperature in the case of the first embodiment. It is a graph based on the inclination of the frequency deviation when it is used as a parameter.
FIG. 12 is a diagram illustrating a DIP phenomenon that is a phenomenon peculiar to a crystal oscillator.
[Explanation of symbols]
1 1a, 1b Piezoelectric oscillator inspection system
2 Personal computer
20 control unit, 21 microprocessor
22 Data processing unit 23 Memory 24 Input / output unit
3 continuous temperature controller
4 Gas blower
5 DUT storage box
6 Temperature detector
7 Frequency measurement section

Claims (6)

In an inspection system for a piezoelectric oscillator that changes a temperature and inspects a frequency temperature characteristic representing a change in frequency deviation indicating a deviation in measurement frequency from a predetermined frequency.
Gas generating means for generating and blowing a gas at a predetermined temperature;
A measured object storage means for storing the piezoelectric oscillator placed in a gas environment of the predetermined temperature;
Temperature detecting means for measuring and outputting the temperature of the piezoelectric oscillator;
Frequency measuring means for measuring and outputting the frequency of the piezoelectric oscillator;
Determination means for determining pass / fail of the piezoelectric oscillator using slopes of a plurality of frequency deviations within a predetermined temperature range of the frequency deviation,
The determination means includes
Four or more predetermined temperatures are provided within a temperature range for determining pass / fail of the piezoelectric oscillator, and in three consecutive temperature intervals at the four predetermined temperatures, the slope of the frequency deviation in the first temperature interval and the third First calculating means for calculating an average value of the slope of the frequency deviation in the temperature interval;
Second calculating means for calculating a slope of a frequency deviation in a second temperature interval located between the first and third temperature intervals;
Comparing means for comparing the absolute value of the difference between the average value and the slope obtained by the second calculating means with a predetermined standard value,
In the temperature range, when the absolute value is smaller than the predetermined standard value, the piezoelectric oscillator is determined as a non-defective product. In an inspection system for a piezoelectric oscillator that changes a temperature and inspects a frequency temperature characteristic representing a change in frequency deviation indicating a deviation in measurement frequency from a predetermined frequency.
Gas generating means for generating and blowing a gas at a predetermined temperature at a predetermined time;
A measured object storage means for storing the piezoelectric oscillator placed in a gas environment of the predetermined temperature;
Frequency measuring means for measuring and outputting the frequency of the piezoelectric oscillator;
Determination means for determining pass / fail of the piezoelectric oscillator using a plurality of frequency deviation slopes within a predetermined time range of the frequency deviation, and
The determination means includes
Four or more predetermined time points are provided in a time range corresponding to a temperature range in which the quality of the piezoelectric oscillator is judged, and the frequency in the first time interval in three consecutive time intervals at the four predetermined time points. First calculating means for calculating an average value of the slope of the deviation and the slope of the frequency deviation in the third time interval;
Second calculating means for calculating a slope of a frequency deviation in a second time interval located between the first and third time intervals;
Comparing means for comparing the absolute value of the difference between the average value and the slope obtained by the second calculating means with a predetermined standard value,
In the time range, when the absolute value is smaller than the predetermined standard value, the piezoelectric oscillator is determined as a non-defective product. The inspection system for a piezoelectric oscillator according to claim 1 or 2, wherein the piezoelectric oscillator is a temperature compensated crystal oscillator equipped with an AT-cut crystal resonator. In the inspection method of the piezoelectric oscillator in which the temperature is varied and the frequency temperature characteristic representing the change of the frequency deviation indicating the deviation of the measurement frequency from the predetermined frequency is inspected.
A blowing process for generating and blowing a gas at a predetermined temperature;
A temperature measuring step for measuring the temperature of the piezoelectric oscillator;
A frequency measurement step of measuring the frequency of the piezoelectric oscillator;
A determination step of determining pass / fail of the piezoelectric oscillator using slopes of a plurality of frequency deviations within a predetermined temperature range of the frequency deviation, and
The determination step includes
Four or more predetermined temperatures are provided within a temperature range for determining the quality of the piezoelectric oscillator, and in three consecutive temperature intervals at the four predetermined temperatures, the slope of the frequency deviation in the first temperature interval and the third A first calculation step of calculating an average value of the slope of the frequency deviation in the temperature interval;
A second calculation step of calculating a slope of a frequency deviation in a second temperature interval located between the first and third temperature intervals;
A comparison step of comparing an absolute value of a difference between the average value and the slope obtained in the second calculation step with a predetermined standard value,
In the temperature range, when the absolute value is smaller than the predetermined standard value, the piezoelectric oscillator is determined as a non-defective product. In the inspection method of the piezoelectric oscillator in which the temperature is varied and the frequency temperature characteristic representing the change of the frequency deviation indicating the deviation of the measurement frequency from the predetermined frequency is inspected.
A blowing process for generating and blowing a gas at a predetermined temperature at a predetermined time;
A frequency measurement step of measuring the frequency of the piezoelectric oscillator;
A determination step of determining pass / fail of the piezoelectric oscillator using slopes of a plurality of frequency deviations within a predetermined time range of the frequency deviation, and
The determination step includes
Four or more predetermined time points are provided in a time range corresponding to a temperature range in which the quality of the piezoelectric oscillator is judged, and the frequency in the first time interval in three consecutive time intervals at the four predetermined time points. A first calculation step of calculating an average value of the slope of the deviation and the slope of the frequency deviation in the third time interval;
A second calculating step of calculating a slope of a frequency deviation in a second time interval located between the first and third time intervals;
A comparison step of comparing an absolute value of a difference between the average value and the slope obtained in the second calculation step with a predetermined standard value,
In the time range, when the absolute value is smaller than the predetermined standard value, the piezoelectric oscillator is determined as a non-defective product. 6. The method for inspecting a piezoelectric oscillator according to claim 4, wherein the piezoelectric oscillator is a temperature-compensated crystal oscillator equipped with an AT-cut crystal resonator.

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