JP3736000B2

JP3736000B2 - Linear actuator

Info

Publication number: JP3736000B2
Application number: JP03750597A
Authority: JP
Inventors: 雅之上山
Original assignee: Konica Minolta Inc
Current assignee: Konica Minolta Inc
Priority date: 1997-02-21
Filing date: 1997-02-21
Publication date: 2006-01-18
Anticipated expiration: 2017-02-21
Also published as: JPH10232337A

Description

【０００１】
【発明の属する技術分野】
本発明は、リニアアクチュエータに関し、詳しくは、電気機械変換素子を用いたリニアアクチュエータに関し、特に精密機器用駆動装置の駆動源として好適なリニアアクチュエータに関する。
【０００２】
【従来の技術】
従来、ビデオカメラ等の精密機器の駆動装置としてリニアアクチュエータが提供されている。
【０００３】
たとえば、特開平４−６９０７０号公報は、図１１に示したように、複数の圧電素子要素が積層されてなる積層型厚電素子２０２、すなわち所定の電気信号を与えることによってその電気信号に応じた変位を発生する電気機械変換素子２０２の積層方向すなわち変位方向の一方の端面２０４に棒状の係合部材２０８が固定されてなるリニアアクチュエータ２００を開示している。この電気機械変換素子２０２の変位方向の他方の端面２０６は、固定部材２０９に固定されるようになっている。被駆動部材２１０は、係合部材２０８と、この係合部材２０８と平行に固定された案内バー２１４とによって摺動可能に支持されている。すなわち、係合部材２０８は、被駆動部材２１０の摺接穴２１２に挿通され、被駆動部材２１０にねじ止めされた板ばね２１６の弾発力によって被駆動部材２１０の摺接穴２１２が係合部材２０８に圧接され、係合部材２０８と被駆動部材２１０とが摩擦係合するようになっている。
【０００４】
この電気機械変換素子２０２の各圧電素子要素は電圧印加によって伸びるので、電気機械変換素子２０２に周期的な電圧を印加して電気機械変換素子２０２を変位方向に伸縮させ、係合部材２０８を軸方向に往復移動させることによって、リニアアクチュエータ２００は被駆動部材２１０を移動させることができる。たとえば電気機械変換素子２０２の伸び速度と縮み速度とが異なり、伸縮時に係合部材２０８と被駆動部材２１０との摩擦係合部において送りと滑りとが交互に生じるように電圧を印加することによって、被駆動部材２１０を間欠的に微少送りすることができる。
【０００５】
すなわち、原理的に説明すると、係合部材２０８がゆっくり移動するときには、被駆動部材２１０は、摩擦係合部における摩擦力によって係合部材２０８とともに移動する。一方、係合部材２０８がある程度以上速く移動して慣性力が摩擦係合部の摩擦力より大きくなったときには、摩擦係合部において滑りが生じ、被駆動部材２１０は静止または略静止したまま、係合部材２０８だけが移動する。したがって、係合部材２０８の一方向の移動時には、被駆動部材２１０を係合部材２０８とともに一体的に移動して送る一方、係合部材２０８の他方向の移動時には、滑りによって被駆動部材２１０を静止または略静止させたまま係合部材２０８を移動させ、これを繰り返すことによって、被駆動部材２１０を一方向に間欠的に移動させることができる。
【０００６】
しかし、このリニアアクチュエータ２００は、電気機械変換素子２０２の端面２０４に長い係合部材２０８が固定されているので、全長が長くなってスペース効率が悪い上に、振動系が長くなって共振点が低下する等のため、リニアアクチュエータ２００の駆動可能周波数が低い範囲に限定され、駆動特性の向上が困難である。
【０００７】
【発明が解決しようとする課題】
したがって、本発明の解決すべき技術的課題は、全長を短くしてスペース効率および駆動特性の向上を図ることができるリニアアクチュエータを提供することである。
【０００８】
【課題を解決するための手段および作用・効果】
上記の技術的課題を解決するため、本発明によれば、以下の構成のリニアアクチュエータが提供される。
【０００９】
リニアアクチュエータは、所定の電気信号を与えることによってその電気信号に応じた変位を発生する電気機械変換素子と、この電気機械変換素子の変位方向の一端面に固定された係合部材とを有する。リニアアクチュエータは、上記係合部材が被駆動部材に摩擦係合する一方、上記電気機械変換素子の変位方向の他の端面が固定部材に支持される。リニアアクチュエータは、上記電気機械変換素子に電圧を印加してこの電気機械変換素子を伸縮させ、上記係合部材と被駆動部材との間の摩擦係合部分における滑りと送りとによって上記被駆動部材を移動させる。上記係合部材は、上記電気機械変換素子の上記一端面に固定される固定壁部と、この固定壁部の周縁に接続され、大略、上記電気機械変換素子の側面に沿って延在する支持壁部と、この支持壁部によって上記電気機械変換素子の側方、すなわち電気機械変換素子の変位方向両端面間において変位方向に対して直角方向外側に支持された摩擦係合部とを有する。
【００１０】
上記構成において、係合部材の固定壁部は電気機械変換素子の一端面に固定され、係合部材の支持壁部は電気機械変換素子の側面に大略沿って延在するので、このリニアアクチュエータの全長を電気機械変換素子の長さ程度にまで短くすることができる。
【００１１】
したがって、全長を短くしてスペース効率および駆動特性の向上を図ることができるリニアアクチュエータを提供することができる。
【００１２】
上記構成のリニアアクチュエータは、種々の態様で具体化される。
【００１３】
好ましくは、上記係合部材は、一体的に形成された上記固定壁部と上記支持壁部と上記摩擦係合部とを有する。上記支持壁部は、第１片と、一対の第２片と、一対の第３片とを有する。上記第１片は、上記固定壁部の上記周縁の一辺から略直角方向に、上記電気機械変換素子の側面に沿って延在する。上記一対の第２片は、上記固定壁部の上記周縁の上記一辺に対して略直角にそれぞれ延在する上記第１片の一対の側辺から略直角に、上記電気機械変換素子を挟んで上記第１片とは反対側まで、上記電気機械変換素子の側面に沿ってそれぞれ延在する。上記一対の第３片は、上記電気機械変換素子を挟んで上記第１片とは反対側の上記一対の第２片の各端辺から、上記電気機械変換素子に対して上記第１片とは反対側方向に互いに略平行に突出して、上記摩擦係合部として、被駆動部材を挟持する。
【００１４】
上記構成において、係合部材の第１片および一対の第２片は、上記電気機械変換素子を包むように電気機械変換素子の周囲に延在し、固定壁部から摩擦係合部である第３片までの距離がある程度長くなっている。したがって、摩擦係合部が所定のばね定数で被駆動部材を挟持するように容易に構成することができる。また、係合部材の第３片を電気機械変換素子に接近して配置し、摩擦係合部と電気機械変換素子との間の距離を短くすることができる。
【００１５】
したがって、係合部材が被駆動部材を挟持し、摩擦係合により電気機械変換素子に作用するモーメントを小さくした簡単な構成のリニアアクチュエータを提供することができる。
【００１６】
好ましくは、上記係合部材は、一体的に形成された上記固定壁部と上記支持壁部と上記摩擦係合部とを有する。上記支持壁部は、第１片と第２片とを有する。上記第１片は、上記固定壁部の上記周縁の一辺から略直角に、上記電気機械変換素子の側面に沿って延在する。上記第２片は、上記第１片の上記固定壁部の上記周縁の上記一辺に対して略直角にそれぞれ延在する上記第１片の一対の側辺の一方から上記電気機械変換素子とは反対側に略直角に延在する。この第２片の両面は、上記摩擦係合部として、被駆動部材に設けられた挾持部に挾持される。
【００１７】
上記構成によれば、被駆動部材の挾持部が挾持する係合部材の第２片の摩擦係合部を、電気機械変換素子に接近して配置することができる。
【００１８】
したがって、係合部材が被駆動部材に挟持され、摩擦係合により電気機械変換素子に作用するモーメントを小さくした簡単な構成のリニアアクチュエータを提供することができる。
【００１９】
好ましくは、上記係合部材は、一体的に形成された上記固定壁部と上記支持壁部と上記摩擦係合部とを有する。上記支持壁部は、上記固定壁部の上記周縁の対向する一対の辺から上記電気機械変換素子の側面に沿ってそれぞれ略直角に延在する一対の係合片からなる。この一対の係合片の上記電気機械変換素子とは反対側の各外面は、上記摩擦係合部として、被駆動部材に設けられた挾持部に挾持される。
【００２０】
上記構成によれば、係合部材は、固定壁部の両側に一対の係合片が大略断面コ字状に結合されてなる。一対の係合片は、電気機械変換素子の両側で被駆動部材の挾持部と摩擦係合する。そして、一方の係合片と挾持部との摩擦係合により電気機械変換素子に作用するモーメントと、他方の係合片と挾持部との摩擦係合により電気機械変換素子に作用するモーメントとは、大きさが略同じで、向きが互いに逆となる。そのため、両モーメントが互いに打ち消し合い、電気機械変換素子にモーメントが作用しないようにすることができる。
【００２１】
したがって、係合部材が被駆動部材に挟持され、摩擦係合によるモーメントの影響をできるだけ小さくした簡単な構成のリニアアクチュエータを提供することができる。
【００２２】
好ましくは、上記係合部材は、一体的に形成された上記固定壁部と上記支持壁部と上記摩擦係合部とを有する。上記支持壁部は、上記固定壁部の上記周縁の対向する一対の辺から上記電気機械変換素子の側面に沿ってそれぞれ直角に延在し、上記固定壁部の上記周縁の上記一対の辺の延在方向に上記電気機械変換素子の側面を越えて両側に互いに略平行に突出する一対の係合片からなる。この一対の係合片は、上記摩擦係合部として、被駆動部材を挟持する。
【００２３】
上記構成において、被駆動部材は、一対の係合片の各突出部の間、すなわち電気機械変換素子の両側において挟持される。つまり、摩擦係合部は、電気機械変換素子の両側に配置される。そのため、摩擦係合により電気機械変換素子に作用するモーメントが互いに打ち消し合い、電気機械変換素子にモーメントが作用しないようにすることができる。
【００２４】
したがって、係合部材が被駆動部材を挟持し、摩擦係合によるモーメントの影響をできるだけ小さくした簡単な構成のリニアアクチュエータを提供することができる。
【００２５】
なお、上記係合部材は、典型的には一枚の板材の曲げ加工により一体的に形成されるが、たとえば、削り出し、溶接、射出成形等によって形成しもよい。
【００２６】
【発明の実施の形態】
以下、本発明を図１の外観図に示したデジタルカメラ１に適用した各実施形態について、図１〜図１０を参照しながら詳細に説明する。
【００２７】
まず、第１実施形態について説明する。本発明を適用したデジタルカメラ１は、薄い直方体形状のハウジング２を有する。ハウジング２の細長い一方の側面２aには、撮影窓３と、露光調整レバー５と、シャッタ釦８２とが配置され、他方の側面２bには、外部電源端子８８と、シリアル出力端子８９とが配置され、上面２cには、撮影映像が表示される液晶モニタ６と、メインスイッチ８０と、ズームスイッチ８１とが配置されている。ハウジング２の内部には、撮影窓３に対向して反対側にＣＣＤ素子９０を有する光学ユニット４と、演算制御回路やフラッシュメモリ等を含む回路基板８と、充電電池９とが収納されている。ＣＣＤ素子９０の受光量は、露光調整レバー５を撮影窓３側にスライドし、光学ユニット４の前に不図示の露光調整用ＮＤフィルタを挿入することによって、調整できるようになっている。
【００２８】
光学ユニット４は、４群のズームレンズ機構を含み、それぞれ１枚または２枚以上のレンズからなる第１〜第４レンズ群１２,２２,３２,４２が、図３に模式的に示したズーム曲線１１,２１,３１,４１を有するようになっている。光学ユニット４は、図２の斜視図に示すように、第１レンズ群１２を含む第１ユニット１０と、第２レンズ群２２を含む第２ユニット２０と、第３レンズ群３２を含む第３ユニット３０と、第４レンズ群４２を含む第４ユニット４０と、ローパスフィルタ５２およびＣＣＤ素子９０を含むベースユニット５０とを備える。第１〜第４ユニット１０,２０,３０,４０は、平板状の移動板１６,２６,３６,４６の上端にレンズ支持部１５,２５,３５,４５が突設されてなる第１〜第４レンズ支持部材１４,２４,３４,４４をそれぞれ含む。各レンズ支持部１５,２５,３５,４５は、第１〜第４レンズ群１２,２２,３２,４２をそれぞれ支持する。ベースユニット５０は、平板状の固定板５６の上端にローパスフィルタ支持部５５およびＣＣＤ素子支持部９２が突設されてなるベース部材５４を含む。ローパスフィルタ支持部５５は、ローパスフィルタ５２を支持し、ＣＣＤ素子支持部９２は、ＣＣＤ素子９０を支持する。ベース部材５４の固定板５６には、図２に示すように、積層された第１〜第４レンズ支持部材１４,２４,３４,４４の移動板１６,２６,３６,４６が載せられ、押さえバネ６４で付勢されるようになっている。
【００２９】
ベース部材５４の固定板５６は、図４(a)に示すように、カム穴５７と、板面に垂直に突設された一対の直進案内ピン５８,５９とを有する。第１〜第４レンズ支持部材１４,２４,３４,４４の移動板１６,２６,３６,４６は、図４(e),(d),(c),(b)に示すように貫通する３つの穴、すなわち、逃げ穴１７およびカム穴２７,３７,４７と、光軸方向に延在する長穴である一対の直進案内穴１８,１９;２８,２９;３８,２９;４８,４９とをそれぞれ有する。各移動板１６,２６,３６,４６の一対の直進案内穴１８,１９;２８,２９;３８,３９;４８,４９には、ベース部材５４の固定板５６の一対の直進案内ピン５８,５９がそれぞれ挿通されて摺接し、第１〜第４レンズ支持部材１４,２４,３４,４４の移動板１６,２３６,３６,４６が、光軸方向に直進案内されながらベース部材５４の固定板５６に支持されている。また、第１レンズ支持部材１４の移動板１６は、図２および図５(e)に示すように、その一端６１が移動板１６に回転自在に固定された連動バー６０を有する。この連動バー６０の他端には、連動ピン６２が突設されている。この連動ピン６２は、第１レンズ支持部材１４の移動板１６の逃げ穴１７を貫通し、第２〜第４レンズ支持部材２４,３４,４４の移動板２６,３６,４６のカム穴２７,３７,４７およびベース部材５４の固定板５６のカム穴５７に挿通されて摺接している。そして、第１レンズ支持部材１４の移動板１６の光軸方向移動に伴って、第２〜第４レンズ支持部材２４,３４,４４の移動板２６,３６,４６は、重なり合った状態のまま光軸方向に移動し、第１〜第４レンズ群１２,２２,３２,４２は、図３に示した所定のズーム移動を行うようになっている。
【００３０】
第１レンズ支持部材１４の移動板１６は、ベース部材５４の固定板５６に固定された駆動部材７０によって、光軸方向に移動させられるようになっている。
【００３１】
駆動部材７０は、図２および図５の斜視図に示すように、積層型圧電素子７４の積層方向の一方の端面に係合部材７６が固定されてなるリニアアクチュエータである。積層型圧電素子７２の他方の端面は、固定部７２に固定される。固定部７２は、ベース部材５４の固定板５６に固定されている。駆動部材７０、すなわち積層型圧電素子７４および係合部材７６は、固定部７２に片持ち支持され、固定板５６から離れた状態で光軸方向に延在している。積層型圧電素子７４は、複数の圧電素子要素が積層されたものであり、積層方向は光軸方向に一致している。積層型圧電素子７４は、電気機械変換素子であって、電圧印加により積層方向に伸縮するようになっている。係合部材７６は、積層型圧電素子７４の端面に固定された固定壁部７７と、この固定壁部７７から積層型圧電素子７４の側面を包むように延在する支持壁部７８とを有する。支持壁部７８は、図５および図６の光軸直角断面図に示すように、固定壁部７７の一辺から積層型圧電素子７４側に略直角に折り曲げられて積層型圧電素子７４の底面７４aを覆う底片７８aと、底片７８aの両側辺から略直角に折り曲げられて積層型圧電素子７４の両側面７４bを覆う一対の側片７８bと、側片７８bの上辺から内側に略直角に折り曲げられて積層型圧電素子７４の上面７４cを覆う２つの上片７８cと、積層型圧電素子７４の上面７４cの略中央部分から上向きに両上片７８cから折り曲げられた２つの立片７８dとからなる。２つ立片７８dは、互いに略平行に延在し、各先端部分には、互いに内側に突出した突出部７８eをそれぞれ有する。両突出部７８eの間には、図２および図６に示すように、第１レンズ支持部材１４の移動部１６の下縁部１６aが弾力的に圧接され、下縁部１６aと突出部７８eとが摩擦係合するようになっている。つまり、この突出部７８eは、摩擦係合部である。
【００３２】
突出部７８eにおける移動板１６との摩擦係合によって、駆動部材７０は、第１レンズ支持部材１４を移動させることができる。すなわち、駆動部材７０の係合部材７６の突出部７８eがゆっくり移動するときには、第１レンズ支持部材１４の移動板１６の下縁部１６aは、突出部７８eと下縁部１６aとの間の摩擦力によって突出部７８eとともに一体的に移動する。一方、突出部７８eが急激に速度を変化しながら移動すると、慣性力が突出部７８eと下縁部１６aとの間の摩擦力より大きくなって両者の間で滑りが起こり、突出部７８eは、下縁部１６aに対して相対的に移動する。したがって、不図示の圧電アクチュエータ駆動手段である電圧発生装置によって、突出部７８eの速度が急激に変化するように急激な電圧変化を含む周期的な電圧、たとえば鋸歯状や全波整流状に変化する電圧を積層型圧電素子７４に印加して、積層型圧電素子７４を伸縮させ、突出部７８eを光軸方向に往復移動させ、たとえば、突出部７８eの往から復への反転時、または、復から往への反転時のいずれか一方において、突出部７８eと下縁部１６aとの間に滑りが起こって両者の間に相対移動が生じ、それ以外のときには、両者の間に相対移動が生じないようにして、第１レンズ支持部材１４を、往方向または復方向のいずれか一方に間欠的に微少送りすることができる。あるいは、突出部７８eの往復移動の往と復との両方において、突出部７８eと下縁部１６aとの間で滑りが生じるが、往と復とで相対滑りの向きと長さとが異なるようにして、第１レンズ支持部材１４を振動させつついずれか一方向に移動させることも可能である。積層型圧電素子７４に印加する電圧パターンを変えることによって、第１レンズ支持部材１４の移動方向を変えることができる。
【００３３】
また、支持壁部７８は、積層型圧電素子７４のまわりを包むように延在するので、固定壁部７７から突出部７８eまでの距離をある程度長くして、所望のばね定数を得るとともに、摩擦係合部を積層型圧電素子７４に接近して配置して、摩擦係合部から積層型圧電素子７４に作用するモーメントをできるだけ小さくすることができる。
【００３４】
上記のように、駆動部材７０によって第１レンズ支持部材１４が光軸方向に移動されると、デジタルカメラ１の光学ユニット４は、連動バー６０の連動ピン６２と各カム穴２７,３７,４７,５７との係合によって、その第２〜第４レンズ支持部材２４,３４,４４が連動して移動される。このとき、第１〜第４レンズ支持部材１４,２４,３４,４４は、押さえバネ６４によって固定板５６に付勢されているので、固定板５６に沿って移動し、また、固定板５６に突設された一対の直進案内ピン５８,５９と各一対の直進案内穴１８,１９;２８,２９;３８,３９;４８,４９との係合によって、光軸方向に直進案内される。したがって、各レンズ支持部１５,２５,３５,４５に固定された各レンズ群１２,２２,３２,４２は、傾くことなく光軸に沿って精度良くズーム移動する。
【００３５】
上記構成において、各レンズ群１２,２２,３２,４２を駆動する各レンズ支持部材１４,２４,３４,４４およびべース部材５４等は、各レンズ群１２,２２,３２,４２の径方向一側に積層されてまとめて配置されるので、その積層厚さを各レンズ群１２,２２,３２,４２の直径と同程度の寸法、またはそれより小さい寸法とすることができる。したがって、一方向の径寸法をできるだけ小さくして薄くしたズームレンズ機構を含む光学ユニット４を構成することができる。
【００３６】
このデジタルカメラ１では、ＣＣＤ素子９０の受光面が小さいため、各レンズ群１２,２２,３２,４２の偏心誤差の許容値が小さい。そのため、各レンズ群１２,２２,３２,４２は、各レンズ支持部材１４,２４,３４,４４およびベース部材５４等の部品精度だけで光軸に対する所定の位置精度を達成するのが困難である。そこで、各レンズ群１２,２２,３２,４２は、各レンズ群１２,２２,３２,４２の取り付けを除いてレンズ支持機構を組み立てた後に、以下のようにして各レンズ支持部材１４,２４,３４,４４のレンズ支持部１５,２５,３５,４５に一つずつ順に調芯しながら固定する。
【００３７】
すなわち、図７の斜視図に示すように、各レンズ群１２,２２,３２,４２の取り付けを除いて組み立てが完了したレンズ支持機構の光軸１０６に沿って前後の所定位置に、投光器１０２と受光器１０３とを固定する。このとき、各レンズ支持部１５,２５,３５,４５は、光軸に沿って配置されている。
【００３８】
次に、適宜に選択したひとつのレンズ群、たとえば第２レンズ群２２の外周面をレンズ把持具１００を用いて把持し、光軸１０６の側方から所定のレンズ支持部２５、すなわちレンズ枠２５に載せ、受光器１０３からの出力を観察しながら、レンズ群２２の中心が光軸１０６に一致するように位置決めする。具体的には、たとえば投光器１０２から光軸に平行な平行光を照射し、焦点距離に応じた位置に受光器１０３を配置し、レンズ群２２を径方向移動して、受光器１０３から観察される結像位置を見ながら、レンズ群２２を位置決めする。そして、レンズ群２２を位置決めした状態で保持したまま、レンズ群２２の周囲に接着剤注入器１０４を用いて接着剤を塗布して、レンズ群２２をレンズ支持部２５に接着する。このとき、接着剤が硬化するまでレンズ群２２を保持することによって、接着中にレンズ群２２の位置ずれを防止できる。なお、レンズ群２２を載せる前にレンズ支持部２５に予め接着剤を塗布しておいてもよい。
【００３９】
以上の作業を、各レンズ群１２,２２,３２,４２について適宜の順序で繰り返すことによって、各レンズ群１２,２２,３２,４２を光軸１０６に沿って高精度に取り付けることができる。
【００４０】
したがって、ズームレンズ機構の前後端に配置されたレンズ群１２,４２のみならず、中間位置に配置されたレンズ群２２,３２についても、調芯を行うことができる。
【００４１】
上記構成において、光学ユニット４は、各レンズ支持部１５,２５,３５,４５の略全周に渡って開放されているので、各レンズ群１２,２２,３２,４２を各レンズ支持部１５,２５,３５,４５まで持って来ることが容易である。もっとも、少なくとも各レンズ群１２,２２,３２,４２の直径に等しい寸法の開口があれば、各レンズ群１２,２２,３２,４２を各レンズ支持部１５,２５,３５,４５まで持って来ることが可能である。
【００４２】
以上説明した第１実施形態では、駆動部材７０の突出部７８eが第１レンズ支持部材１６の下縁部１６aを挾持していたが、逆に、図８および図９の要部斜視図に示した第２および第３実施形態のように、駆動部材７０x,７０yが挾持されるように構成することもできる。以下、第２および第３実施形態について、第１実施形態との相違点を中心に説明する。
【００４３】
すなわち、図８に示した第２実施形態では、駆動部材７０xの係合部材７６xは、積層型圧電素子７４の端部に固定された固定壁部７７と、この固定壁部７７から積層型圧電素子７４の片側に延在する支持壁部７８xとを有する。支持壁部７８xは、固定壁部７７の一辺から積層型圧電素子７４側に略直角に折り曲げられて積層型圧電素子７４の一側面を覆う第１片、すなわち側片７８sと、側片７８sの上辺から積層型圧電素子７４とは反対側に略直角に折り曲げられた第２片、すなわち翼片７８tとからなる。翼片７８tは、光軸方向移動自在に固定された移動板１６xと、移動板１６xに固定された押さえ板１６sとの間に挾持され、摩擦係合されるようになっている。したがって、第１実施形態と同様に積層型圧電素子７４を所定のパターンで伸縮させ、移動板１６xおよび押さえ板１６sと駆動部材７０xの翼片７８tとの間における滑りと送りとによって、移動板１６xおよび押さえ板１６sと駆動部材７０xの翼片７８tとの相対移動を間欠的に生じさせて、移動板１６xを移動させることができる。翼片７８tは積層型圧電素子７４に接近して配置されてているので、簡単な構成で、摩擦係合部から積層型圧電素子７４に作用するモーメントをできるだけ小さくなるようにすることができる。
【００４４】
また、図９に示した第３実施形態では、駆動部材７０yの係合部材７６yは、積層型圧電素子７４の端部に固定された固定壁部７７と、この固定壁部７７の上辺および下辺から略直角に折り曲げられて積層型圧電素子７４の上下両側に沿って延在する一対の支持壁部７８yとを有する。一対の支持壁部７８y、すなわち係合片は、光軸方向移動自在に固定された移動板１６yと、移動板１６yに固定された押さえ板１６tとの間に挾持され、積層型圧電素子７４を挟んで両側で摩擦係合するようになっている。したがって、摩擦係合部から積層型圧電素子７４に作用するモーメントが打ち消し合うようにすれば、簡単な構成で、積層型圧電素子７４に全体としてモーメントが作用しないようにすることができる。
【００４５】
なお、上記第２および第３実施形態において、移動板１６x,１６yの一端の突起１６bは、第１実施形態の第１レンズ支持部材１４と略同様に構成された不図示の第１レンズ支持部材に固定または係合され、移動板１６xと一体的に、不図示の第１レンズ支持部材が光軸方向両方向に移動されるようになっている。
【００４６】
次に、第３実施形態と同様に、駆動部材７０zが積層型圧電素子７４の両側に摩擦係合部を有する第４実施形態について、図１０の要部斜視図を参照しながら説明する。
【００４７】
すなわち、移動板１６zには、光軸方向に延在する切欠き１６cが形成され、この切欠き１６c内に駆動部材７０zが配置される。駆動部材７０zの係合部材７６zは、積層型圧電素子７４の端面に固定された固定壁部７７と、この固定壁部７７の上辺および下辺から略直角に折り曲げられて積層型圧電素子７４の上下両側に沿って延在する一対の支持壁部７８zとを有する。一対の支持壁部７８zは、積層型圧電素子７４の上面および下面から左右両側にそれぞれ突出する。この支持壁部７８Zの左右両端部には、互いに内側に向いて突出する突出部７８vがそれぞれ形成されている。この対向する突出部７８v間の間隔が狭くなっている部分７８wは、移動板１６zの切欠き１６cの両側の周囲１６dを挟持して摩擦係合するようになっている。この駆動部材７０は、摩擦係合部が積層型圧電素子７４を挟んで両側に配置されているため、左右の各摩擦係合部から積層型圧電素子７４に作用するモーメントが打ち消し合って、積層型圧電素子７４にはモーメントが作用しないようにすることができる。
【００４８】
なお、本発明は上記各実施形態に限定されるものではなく、その他種々の態様で実施可能である。たとえば、移動板１６,２６,３６,４６の両側に２組のズームレンズ光学系を配置する構成としてもよい。また、開示されたリニアアクチュエータ、すなわち駆動部材７０,７０ｘ,７０ｙ,７０ｚは、所定の電気信号を与えるとその電気信号に応じた変位を発生する電気機械変換素子として積層型圧電素子７４を用いているが、他の電気機械変換素子、たとえば、静電アクチュエータや電歪素子等を用いてもよい。また、開示されたリニアアクチュエータ７０,７０ｘ,７０ｙ,７０ｚは、ズームレンズ機構以外の種々の分野で利用可能である。
【図面の簡単な説明】
【図１】本発明の第１実施形態のデジタルカメラの外観図である。
【図２】図１のデジタルカメラの光学ユニットの斜視図である。
【図３】図２のズームレンズの説明図である。
【図４】図２の各レンズ支持部材の移動板およびベース部材の固定板の平面図である。
【図５】図２の駆動部材の斜視図である。
【図６】図５の線VI-VIに沿って切断した断面図である。
【図７】図２の光学ユニットのレンズ群の取り付け方法の説明図である。
【図８】本発明の第２実施形態の駆動部材の要部斜視図である。
【図９】本発明の第３実施形態の駆動部材の要部斜視図である。
【図１０】本発明の第４実施形態の駆動部材の要部斜視図である。
【図１１】従来のリニアアクチュエータを用いた駆動装置の要部斜視図である。
【符号の説明】
１デジタルカメラ
２ハウジング
２a,２b 側面
２c 上面
３撮影窓
４光学ユニット
５露光調整レバー
６液晶モニタ
８回路基板
９充電電池
１０第１ユニット
１１ズーム曲線
１２第１レンズ群
１４第１レンズ支持部材
１５レンズ支持部（レンズ枠）
１６移動板
１６a 下縁部
１６b 突出部
１６c 切欠き
１６d 周囲
１６s,１６t 押さえ板
１６x,１６y,１６z 移動板
１７逃げ穴
１８直進案内穴
１９直進案内穴
２０第２ユニット
２１ズーム曲線
２２第２レンズ群
２４第２レンズ支持部材
２５レンズ支持部（レンズ枠）
２６移動板
２７カム穴（第２駆動手段）
２８直進案内穴
２９直進案内穴
３０第３ユニット
３１ズーム曲線
３２第３レンズ群
３４第３レンズ支持部材
３５レンズ支持部（レンズ枠）
３６移動板
３７カム穴（第２駆動手段）
３８直進案内穴
３９直進案内穴
４０第４ユニット
４１ズーム曲線
４２第４レンズ群
４４第４レンズ支持部材
４５レンズ支持部（レンズ枠）
４６移動板
４７カム穴（第２駆動手段）
４８直進案内穴
４９直進案内穴
５０ベースユニット
５２ローパスフィルタ
５４ベース部材
５５ローパスフィルタ支持部
５６固定板
５７カム穴（第２駆動手段）
５８直進案内ピン
５９直進案内ピン
６０連動バー（第２駆動手段）
６１一端
６２連動ピン
６４押さえバネ
７０,７０x,７０y,７０z 駆動部材（駆動手段、第１駆動手段、リニアアクチュエータ）
７２固定部
７４積層型圧電素子（電気機械変換素子）
７４a 底面
７４b 側面
７４c 上面
７６,７６x,７６y,７６z 係合部材
７７固定壁部
７８支持壁部
７８a 底片（第１片）
７８b 側片（第２片）
７８c 上片（第２片）
７８d 立片（第３片）
７８e 突出部（摩擦係合部）
７８s 側片（第１片）
７８t 翼片（第２片）
７８v 突出部（摩擦係合部）
７８w 間隔の狭い部分
７８x 支持壁部
７８y,７８z 支持壁部（係合片）
８０メインスイッチ
８１ズームスイッチ
８２シャッタ釦
８８外部電源端子
８９シリアル出力端子
９０ＣＣＤ素子
９２ＣＣＤ支持部
１００レンズ把持具
１０２投光器
１０３受光器
１０４接着剤注入器
１０６光軸[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a linear actuator, and more particularly to a linear actuator using an electromechanical transducer, and more particularly to a linear actuator suitable as a drive source for a precision device drive device.
[0002]
[Prior art]
Conventionally, linear actuators have been provided as driving devices for precision equipment such as video cameras.
[0003]
For example, as shown in FIG. 11, Japanese Patent Laid-Open No. 4-69070 discloses a laminated thick electric element 202 in which a plurality of piezoelectric element elements are laminated, that is, according to an electric signal by giving a predetermined electric signal. A linear actuator 200 is disclosed in which a rod-like engagement member 208 is fixed to one end face 204 in the stacking direction of the electromechanical conversion element 202 that generates the displacement, that is, the displacement direction. The other end face 206 in the displacement direction of the electromechanical conversion element 202 is fixed to the fixing member 209. The driven member 210 is slidably supported by an engaging member 208 and a guide bar 214 fixed in parallel with the engaging member 208. That is, the engaging member 208 is inserted into the sliding contact hole 212 of the driven member 210, and the sliding contact hole 212 of the driven member 210 is engaged by the elastic force of the leaf spring 216 screwed to the driven member 210. The engagement member 208 and the driven member 210 are frictionally engaged with each other by being pressed against the member 208.
[0004]
Since each piezoelectric element element of the electromechanical transducer 202 is extended by applying a voltage, a periodic voltage is applied to the electromechanical transducer 202 to expand and contract the electromechanical transducer 202 in the displacement direction, and the engaging member 208 is pivoted. The linear actuator 200 can move the driven member 210 by reciprocating in the direction. For example, by applying a voltage so that the extension speed and the contraction speed of the electromechanical conversion element 202 are different, and feeding and slipping occur alternately in the friction engagement portion between the engagement member 208 and the driven member 210 during expansion and contraction. The driven member 210 can be intermittently finely fed.
[0005]
That is, in principle, when the engagement member 208 moves slowly, the driven member 210 moves together with the engagement member 208 by the frictional force in the friction engagement portion. On the other hand, when the engagement member 208 moves faster than a certain degree and the inertial force becomes larger than the frictional force of the frictional engagement portion, slip occurs in the frictional engagement portion, and the driven member 210 remains stationary or substantially stationary. Only the engagement member 208 moves. Therefore, when the engaging member 208 moves in one direction, the driven member 210 is moved together with the engaging member 208 and sent, while when the engaging member 208 moves in the other direction, the driven member 210 is slipped. The driven member 210 can be intermittently moved in one direction by moving the engaging member 208 while being stationary or substantially stationary, and repeating this.
[0006]
However, since the long engagement member 208 is fixed to the end surface 204 of the electromechanical conversion element 202, the linear actuator 200 has a long overall length and poor space efficiency, and has a long vibration system and a resonance point. Due to a decrease, the driveable frequency of the linear actuator 200 is limited to a low range, and it is difficult to improve the drive characteristics.
[0007]
[Problems to be solved by the invention]
Therefore, the technical problem to be solved by the present invention is to provide a linear actuator capable of shortening the overall length and improving space efficiency and driving characteristics.
[0008]
[Means for solving the problems and actions / effects]
In order to solve the above technical problem, according to the present invention, a linear actuator having the following configuration is provided.
[0009]
The linear actuator includes an electromechanical conversion element that generates a displacement according to an electric signal by applying a predetermined electric signal, and an engagement member fixed to one end surface of the electromechanical conversion element in the displacement direction. In the linear actuator, the engaging member is frictionally engaged with the driven member, while the other end surface of the electromechanical conversion element in the displacement direction is supported by the fixing member. The linear actuator applies a voltage to the electromechanical conversion element to expand and contract the electromechanical conversion element, and the driven member is caused by sliding and feeding at a frictional engagement portion between the engaging member and the driven member. Move. The engaging member is fixed to the one end surface of the electromechanical conversion element, and a support connected to the periphery of the fixed wall and extending substantially along the side surface of the electromechanical conversion element. It has a wall part, and the friction engagement part supported by the support wall part to the side of the said electromechanical conversion element, ie, the outer side in the direction orthogonal to a displacement direction, between the displacement direction both ends of an electromechanical conversion element.
[0010]
In the above configuration, the fixed wall portion of the engagement member is fixed to one end surface of the electromechanical conversion element, and the support wall portion of the engagement member extends substantially along the side surface of the electromechanical conversion element. The total length can be shortened to the length of the electromechanical transducer.
[0011]
Therefore, it is possible to provide a linear actuator that can shorten the overall length and improve space efficiency and drive characteristics.
[0012]
The linear actuator having the above configuration is embodied in various modes.
[0013]
Preferably, the engagement member includes the fixed wall portion, the support wall portion, and the friction engagement portion that are integrally formed. The support wall portion includes a first piece, a pair of second pieces, and a pair of third pieces. The first piece extends along a side surface of the electromechanical transducer in a substantially right angle direction from one side of the peripheral edge of the fixed wall portion. The pair of second pieces sandwich the electromechanical conversion element at a substantially right angle from a pair of sides of the first piece that extend substantially perpendicular to the one side of the peripheral edge of the fixed wall portion. Each extends along the side surface of the electromechanical conversion element to the side opposite to the first piece. The pair of third pieces are connected to the electromechanical conversion element from the end sides of the pair of second pieces opposite to the first piece with the electromechanical conversion element interposed therebetween. Project substantially parallel to each other in the opposite direction, and sandwich the driven member as the friction engagement portion.
[0014]
In the above-described configuration, the first piece and the pair of second pieces of the engaging member extend around the electromechanical conversion element so as to wrap the electromechanical conversion element, and are third friction engagement portions from the fixed wall portion. The distance to the piece is longer. Therefore, the friction engagement portion can be easily configured so as to hold the driven member with a predetermined spring constant. In addition, the third piece of the engagement member can be disposed close to the electromechanical conversion element, and the distance between the friction engagement portion and the electromechanical conversion element can be shortened.
[0015]
Therefore, it is possible to provide a linear actuator having a simple configuration in which the engagement member sandwiches the driven member and the moment acting on the electromechanical conversion element by friction engagement is reduced.
[0016]
Preferably, the engagement member includes the fixed wall portion, the support wall portion, and the friction engagement portion that are integrally formed. The support wall portion includes a first piece and a second piece. The first piece extends along a side surface of the electromechanical conversion element at a substantially right angle from one side of the peripheral edge of the fixed wall portion. The second piece is the electromechanical conversion element from one of a pair of side sides of the first piece extending substantially perpendicular to the one side of the peripheral edge of the fixed wall portion of the first piece. It extends at a substantially right angle to the opposite side. Both surfaces of the second piece are held by the holding portions provided on the driven member as the friction engagement portions.
[0017]
According to the above configuration, the friction engagement portion of the second piece of the engagement member that is held by the holding portion of the driven member can be disposed close to the electromechanical conversion element.
[0018]
Therefore, it is possible to provide a linear actuator having a simple configuration in which the engaging member is sandwiched between the driven members and the moment acting on the electromechanical conversion element due to frictional engagement is reduced.
[0019]
Preferably, the engagement member includes the fixed wall portion, the support wall portion, and the friction engagement portion that are integrally formed. The support wall portion includes a pair of engaging pieces that extend substantially at right angles along a side surface of the electromechanical transducer from a pair of opposing sides of the peripheral edge of the fixed wall portion. The outer surfaces of the pair of engaging pieces on the opposite side to the electromechanical conversion element are held as gripping portions provided on the driven member as the friction engaging portions.
[0020]
According to the above configuration, the engagement member is formed by coupling a pair of engagement pieces on both sides of the fixed wall portion in a generally U-shaped cross section. The pair of engagement pieces are frictionally engaged with the holding portions of the driven member on both sides of the electromechanical conversion element. The moment acting on the electromechanical conversion element due to the frictional engagement between the one engagement piece and the holding portion and the moment acting on the electromechanical conversion element due to the frictional engagement between the other engagement piece and the holding portion are: The sizes are substantially the same and the directions are opposite to each other. Therefore, both moments cancel each other, and the moment can be prevented from acting on the electromechanical transducer.
[0021]
Therefore, it is possible to provide a linear actuator having a simple configuration in which the engaging member is held between the driven members and the influence of the moment due to the frictional engagement is made as small as possible.
[0022]
Preferably, the engagement member includes the fixed wall portion, the support wall portion, and the friction engagement portion that are integrally formed. The support wall portion extends at right angles along the side surface of the electromechanical conversion element from a pair of opposite sides of the peripheral edge of the fixed wall portion, and the pair of side edges of the fixed wall portion It consists of a pair of engaging pieces that project substantially parallel to each other on both sides of the electromechanical conversion element in the extending direction. The pair of engagement pieces sandwich the driven member as the friction engagement portion.
[0023]
In the above configuration, the driven member is sandwiched between the protrusions of the pair of engaging pieces, that is, on both sides of the electromechanical conversion element. That is, the friction engagement portions are disposed on both sides of the electromechanical conversion element. Therefore, the moments acting on the electromechanical transducer due to frictional engagement cancel each other, and the moment can be prevented from acting on the electromechanical transducer.
[0024]
Accordingly, it is possible to provide a linear actuator having a simple configuration in which the engagement member sandwiches the driven member and the influence of the moment due to the friction engagement is minimized.
[0025]
The engaging member is typically integrally formed by bending a single plate material, but may be formed by cutting, welding, injection molding, or the like.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments in which the present invention is applied to the digital camera 1 shown in the external view of FIG. 1 will be described in detail below with reference to FIGS.
[0027]
First, the first embodiment will be described. A digital camera 1 to which the present invention is applied has a thin rectangular parallelepiped housing 2. The photographing window 3, the exposure adjustment lever 5, and the shutter button 82 are arranged on one side surface 2a of the housing 2, and the external power terminal 88 and the serial output terminal 89 are arranged on the other side surface 2b. On the upper surface 2c, a liquid crystal monitor 6 on which a captured image is displayed, a main switch 80, and a zoom switch 81 are arranged. Housed in the housing 2 are an optical unit 4 having a CCD element 90 facing the imaging window 3 on the opposite side, a circuit board 8 including an arithmetic control circuit and a flash memory, and a rechargeable battery 9. . The amount of light received by the CCD element 90 can be adjusted by sliding the exposure adjustment lever 5 toward the photographing window 3 and inserting an exposure adjustment ND filter (not shown) in front of the optical unit 4.
[0028]
The optical unit 4 includes four groups of zoom lens mechanisms, and the first to fourth lens groups 12, 22, 32, and 42 each including one lens or two or more lenses are schematically illustrated in FIG. It has curves 11, 21, 31, 41. As shown in the perspective view of FIG. 2, the optical unit 4 includes a first unit 10 including the first lens group 12, a second unit 20 including the second lens group 22, and a third unit including the third lens group 32. The unit 30 includes a fourth unit 40 including a fourth lens group 42, and a base unit 50 including a low-pass filter 52 and a CCD element 90. The first to fourth units 10, 20, 30, and 40 have first to first lens support portions 15, 25, 35, and 45 that protrude from upper ends of flat plate-shaped moving plates 16, 26, 36, and 46. Four lens support members 14, 24, 34, 44 are included, respectively. The lens support portions 15, 25, 35, and 45 support the first to fourth lens groups 12, 22, 32, and 42, respectively. The base unit 50 includes a base member 54 in which a low-pass filter support portion 55 and a CCD element support portion 92 are projected from the upper end of a flat fixed plate 56. The low-pass filter support unit 55 supports the low-pass filter 52, and the CCD element support unit 92 supports the CCD element 90. As shown in FIG. 2, the movable plates 16, 26, 36, 46 of the laminated first to fourth lens support members 14, 24, 34, 44 are placed on the fixed plate 56 of the base member 54 and pressed. The spring 64 is biased.
[0029]
As shown in FIG. 4A, the fixing plate 56 of the base member 54 includes a cam hole 57 and a pair of straight guide pins 58 and 59 projecting perpendicularly to the plate surface. The moving plates 16, 26, 36, 46 of the first to fourth lens support members 14, 24, 34, 44 penetrate as shown in FIGS. 4 (e), (d), (c), (b). Three holes, that is, the escape hole 17 and the cam holes 27, 37, 47, and a pair of straight guide holes 18, 19; 28, 29; 38, 29; 48, 49 that are elongated holes extending in the optical axis direction Respectively. A pair of rectilinear guide holes 18, 19; 28, 29; 38, 39; 48, 49 of each moving plate 16, 26, 36, 46 are inserted into a pair of rectilinear guide pins 58, 59 of the fixed plate 56 of the base member 54. Are inserted and slidably contacted with each other, and the moving plates 16, 236, 36, 46 of the first to fourth lens support members 14, 24, 34, 44 are linearly guided in the optical axis direction while being fixedly guided to the fixing plate 56 of the base member 54. It is supported by. Further, the moving plate 16 of the first lens support member 14 has an interlocking bar 60 whose one end 61 is rotatably fixed to the moving plate 16 as shown in FIG. 2 and FIG. An interlocking pin 62 projects from the other end of the interlocking bar 60. The interlocking pin 62 passes through the escape hole 17 of the moving plate 16 of the first lens support member 14, and the cam holes 27, 36, 46 of the moving plates 26, 36, 46 of the second to fourth lens support members 24, 34, 44. 37 and 47 and the cam hole 57 of the fixing plate 56 of the base member 54 are inserted and slidably contacted. As the moving plate 16 of the first lens support member 14 moves in the optical axis direction, the moving plates 26, 36, 46 of the second to fourth lens support members 24, 34, 44 remain in an overlapping state. Moving in the axial direction, the first to fourth lens groups 12, 22, 32, 42 perform the predetermined zoom movement shown in FIG.
[0030]
The moving plate 16 of the first lens support member 14 is moved in the optical axis direction by a driving member 70 fixed to the fixed plate 56 of the base member 54.
[0031]
As shown in the perspective views of FIGS. 2 and 5, the drive member 70 is a linear actuator in which an engagement member 76 is fixed to one end surface in the stacking direction of the stacked piezoelectric element 74. The other end face of the multilayer piezoelectric element 72 is fixed to the fixing portion 72. The fixing portion 72 is fixed to the fixing plate 56 of the base member 54. The drive member 70, that is, the laminated piezoelectric element 74 and the engagement member 76 are cantilevered by the fixing portion 72 and extend in the optical axis direction while being separated from the fixing plate 56. The stacked piezoelectric element 74 is formed by stacking a plurality of piezoelectric element elements, and the stacking direction coincides with the optical axis direction. The laminated piezoelectric element 74 is an electromechanical conversion element, and expands and contracts in the laminating direction when a voltage is applied. The engaging member 76 has a fixed wall portion 77 fixed to the end face of the multilayer piezoelectric element 74 and a support wall portion 78 extending from the fixed wall portion 77 so as to wrap the side surface of the multilayer piezoelectric element 74. As shown in the cross-sectional views perpendicular to the optical axis in FIGS. 5 and 6, the support wall portion 78 is bent at a substantially right angle from one side of the fixed wall portion 77 toward the multilayer piezoelectric element 74 side, and the bottom surface 74 a of the multilayer piezoelectric element 74. A bottom piece 78a covering the side piece, a pair of side pieces 78b which are bent at substantially right angles from both sides of the bottom piece 78a and covering both side faces 74b of the multilayer piezoelectric element 74, and are bent at substantially right angles from the upper sides of the side pieces 78b. It consists of two upper pieces 78c covering the upper surface 74c of the laminated piezoelectric element 74 and two standing pieces 78d bent upward from both upper pieces 78c upward from a substantially central portion of the upper surface 74c of the laminated piezoelectric element 74. The two upright pieces 78d extend substantially parallel to each other, and each tip portion has a protruding portion 78e protruding inward from each other. As shown in FIGS. 2 and 6, the lower edge portion 16a of the moving portion 16 of the first lens support member 14 is elastically pressed between the protruding portions 78e, and the lower edge portion 16a and the protruding portion 78e Are in frictional engagement. That is, the protrusion 78e is a friction engagement portion.
[0032]
The drive member 70 can move the first lens support member 14 by frictional engagement with the moving plate 16 at the protrusion 78e. That is, when the projecting portion 78e of the engaging member 76 of the driving member 70 moves slowly, the lower edge portion 16a of the moving plate 16 of the first lens support member 14 is subjected to friction between the projecting portion 78e and the lower edge portion 16a. It moves together with the protrusion 78e by force. On the other hand, when the protruding portion 78e moves while changing its speed rapidly, the inertial force becomes larger than the frictional force between the protruding portion 78e and the lower edge portion 16a, causing slippage between the two, and the protruding portion 78e It moves relative to the lower edge portion 16a. Therefore, a voltage generator, which is a piezoelectric actuator driving means (not shown), changes to a periodic voltage including a rapid voltage change, for example, a sawtooth shape or a full-wave rectified shape, so that the speed of the protrusion 78e changes rapidly. A voltage is applied to the multilayer piezoelectric element 74 to expand and contract the multilayer piezoelectric element 74 and to reciprocate the protrusion 78e in the optical axis direction. For example, when the protrusion 78e is reversed from forward to backward, or In any one of the reversals from forward to backward, slip occurs between the projecting portion 78e and the lower edge portion 16a and relative movement occurs between them. In other cases, relative movement occurs between the two. In this manner, the first lens support member 14 can be minutely fed intermittently in either the forward direction or the backward direction. Alternatively, in both the forward and backward movements of the protrusion 78e, slip occurs between the protrusion 78e and the lower edge 16a, but the relative slip direction and length are different between the forward and backward. Thus, the first lens support member 14 can be moved in any one direction while vibrating. By changing the voltage pattern applied to the multilayer piezoelectric element 74, the moving direction of the first lens support member 14 can be changed.
[0033]
Further, since the support wall 78 extends so as to wrap around the multilayer piezoelectric element 74, the distance from the fixed wall 77 to the protrusion 78e is increased to some extent to obtain a desired spring constant, and the frictional engagement By arranging the joint portion close to the multilayer piezoelectric element 74, the moment acting on the multilayer piezoelectric element 74 from the friction engagement portion can be made as small as possible.
[0034]
As described above, when the first lens support member 14 is moved in the optical axis direction by the drive member 70, the optical unit 4 of the digital camera 1 has the interlocking pin 62 of the interlocking bar 60 and the cam holes 27, 37, 47. , 57, the second to fourth lens support members 24, 34, 44 are moved in conjunction with each other. At this time, since the first to fourth lens support members 14, 24, 34, 44 are urged against the fixing plate 56 by the pressing spring 64, the first to fourth lens supporting members 14, 24, 34, 44 move along the fixing plate 56. By engaging the pair of projecting guide pins 58 and 59 and the pair of rectilinear guide holes 18, 19; 28, 29; 38, 39; Accordingly, the lens groups 12, 22, 32, and 42 fixed to the lens support portions 15, 25, 35, and 45 zoom with high precision along the optical axis without tilting.
[0035]
In the above-described configuration, the lens support members 14, 24, 34, 44 and the base member 54 that drive the lens groups 12, 22, 32, 42 are arranged in the radial direction of the lens groups 12, 22, 32, 42. Since they are laminated on one side and arranged together, the thickness of the lamination can be made to be the same size as the diameter of each lens group 12, 22, 32, 42 or smaller. Therefore, it is possible to configure the optical unit 4 including the zoom lens mechanism in which the diameter dimension in one direction is made as small as possible.
[0036]
In this digital camera 1, since the light receiving surface of the CCD element 90 is small, the tolerance value of the eccentric error of each lens group 12, 22, 32, 42 is small. Therefore, it is difficult for the lens groups 12, 22, 32, and 42 to achieve a predetermined positional accuracy with respect to the optical axis only with the accuracy of the components of the lens support members 14, 24, 34, and 44, the base member 54, and the like. . Therefore, each lens group 12, 22, 32, 42 is assembled with the lens support mechanism except for the attachment of each lens group 12, 22, 32, 42, and then each lens support member 14, 24, It fixes to the lens support parts 15,25,35,45 of 34,44, aligning one by one in order.
[0037]
That is, as shown in the perspective view of FIG. 7, the projector 102 and the projector 102 are arranged at predetermined positions along the optical axis 106 of the lens support mechanism that has been assembled except for the attachment of the lens groups 12, 22, 32, 42. The light receiver 103 is fixed. At this time, the lens support portions 15, 25, 35, and 45 are arranged along the optical axis.
[0038]
Next, one lens group selected appropriately, for example, the outer peripheral surface of the second lens group 22 is gripped by using the lens gripper 100, and a predetermined lens support portion 25, that is, the lens frame 25, from the side of the optical axis 106. The lens group 22 is positioned so that the center of the lens group 22 coincides with the optical axis 106 while observing the output from the light receiver 103. Specifically, for example, parallel light parallel to the optical axis is irradiated from the projector 102, the light receiver 103 is disposed at a position corresponding to the focal length, the lens group 22 is moved in the radial direction, and the light is observed from the light receiver 103. The lens group 22 is positioned while looking at the imaging position. Then, with the lens group 22 held in a positioned state, an adhesive is applied around the lens group 22 using an adhesive injector 104 to adhere the lens group 22 to the lens support portion 25. At this time, by holding the lens group 22 until the adhesive is cured, the positional deviation of the lens group 22 can be prevented during bonding. Note that an adhesive may be applied to the lens support portion 25 in advance before mounting the lens group 22.
[0039]
The lens groups 12, 22, 32, and 42 can be attached with high accuracy along the optical axis 106 by repeating the above operations for the lens groups 12, 22, 32, and 42 in an appropriate order.
[0040]
Therefore, not only the lens groups 12 and 42 arranged at the front and rear ends of the zoom lens mechanism, but also the lens groups 22 and 32 arranged at the intermediate positions can be aligned.
[0041]
In the above configuration, the optical unit 4 is opened over substantially the entire circumference of each lens support portion 15, 25, 35, 45, so that each lens group 12, 22, 32, 42 is connected to each lens support portion 15, It is easy to bring up to 25, 35, 45. However, if there is an opening having a size at least equal to the diameter of each lens group 12, 22, 32, 42, each lens group 12, 22, 32, 42 is brought to each lens support 15, 25, 35, 45. It is possible.
[0042]
In the first embodiment described above, the protruding portion 78e of the driving member 70 holds the lower edge portion 16a of the first lens support member 16, but conversely, it is shown in the perspective view of the main part in FIGS. As in the second and third embodiments, the drive members 70x and 70y can be held. Hereinafter, the second and third embodiments will be described focusing on differences from the first embodiment.
[0043]
That is, in the second embodiment shown in FIG. 8, the engaging member 76 x of the drive member 70 x includes the fixed wall 77 fixed to the end of the multilayer piezoelectric element 74, and the multilayer piezoelectric from the fixed wall 77. And a support wall portion 78x extending to one side of the element 74. The support wall portion 78x is bent at a substantially right angle from one side of the fixed wall portion 77 to the multilayer piezoelectric element 74 side, and covers a side surface of the multilayer piezoelectric element 74, that is, a side piece 78s and a side piece 78s. It consists of a second piece, that is, a wing piece 78t, which is bent at a substantially right angle on the opposite side of the multilayer piezoelectric element 74 from the upper side. The wing piece 78t is sandwiched and frictionally engaged between a moving plate 16x fixed so as to be movable in the optical axis direction and a holding plate 16s fixed to the moving plate 16x. Accordingly, as in the first embodiment, the laminated piezoelectric element 74 is expanded and contracted in a predetermined pattern, and the moving plate 16x is moved and slipped between the moving plate 16x and the holding plate 16s and the blade piece 78t of the driving member 70x. Further, the moving plate 16x can be moved by intermittently causing relative movement between the pressing plate 16s and the blade piece 78t of the driving member 70x. Since the blade piece 78t is disposed close to the multilayer piezoelectric element 74, the moment acting on the multilayer piezoelectric element 74 from the friction engagement portion can be made as small as possible with a simple configuration.
[0044]
In the third embodiment shown in FIG. 9, the engaging member 76y of the driving member 70y includes a fixed wall 77 fixed to the end of the multilayer piezoelectric element 74, and the upper and lower sides of the fixed wall 77. And a pair of support wall portions 78y that are bent substantially at right angles and extend along the upper and lower sides of the multilayer piezoelectric element 74. The pair of support wall portions 78y, that is, the engagement pieces, are sandwiched between a moving plate 16y fixed so as to be movable in the optical axis direction and a pressing plate 16t fixed to the moving plate 16y. It is designed to be frictionally engaged on both sides. Therefore, if the moments acting on the multilayer piezoelectric element 74 from the friction engagement portion cancel each other, the moment can be prevented from acting on the multilayer piezoelectric element 74 as a whole with a simple configuration.
[0045]
In the second and third embodiments, the projection 16b at one end of the movable plates 16x and 16y has a first lens support member (not shown) configured substantially the same as the first lens support member 14 of the first embodiment. The first lens support member (not shown) is moved in both directions in the optical axis direction integrally with the moving plate 16x.
[0046]
Next, as in the third embodiment, a fourth embodiment in which the drive member 70z has friction engagement portions on both sides of the multilayer piezoelectric element 74 will be described with reference to a perspective view of a main part in FIG.
[0047]
That is, the moving plate 16z is formed with a notch 16c extending in the optical axis direction, and the drive member 70z is disposed in the notch 16c. The engaging member 76z of the drive member 70z is fixed to the end face of the multilayer piezoelectric element 74, and is bent at a substantially right angle from the upper and lower sides of the fixed wall 77 to And a pair of support wall portions 78z extending along both sides. The pair of support wall portions 78z protrude from the upper surface and the lower surface of the multilayer piezoelectric element 74 to the left and right sides, respectively. Projecting portions 78v projecting inward from each other are formed on the left and right ends of the support wall portion 78Z. The portion 78w in which the interval between the opposing projecting portions 78v is narrow is configured to be frictionally engaged by sandwiching the periphery 16d on both sides of the notch 16c of the moving plate 16z. In this drive member 70, the frictional engagement portions are arranged on both sides of the laminated piezoelectric element 74, so that moments acting on the laminated piezoelectric element 74 from the left and right frictional engagement portions cancel each other out. The moment can be prevented from acting on the piezoelectric element 74.
[0048]
In addition, this invention is not limited to said each embodiment, It can implement in another various aspect. For example, two sets of zoom lens optical systems may be arranged on both sides of the moving plates 16, 26, 36 and 46. Further, the disclosed linear actuators, that is, the drive members 70, 70x, 70y, and 70z use the multilayer piezoelectric element 74 as an electromechanical conversion element that generates a displacement according to the predetermined electric signal. However, other electromechanical conversion elements such as an electrostatic actuator and an electrostrictive element may be used. The disclosed linear actuators 70, 70x, 70y, and 70z can be used in various fields other than the zoom lens mechanism.
[Brief description of the drawings]
FIG. 1 is an external view of a digital camera according to a first embodiment of the present invention.
2 is a perspective view of an optical unit of the digital camera in FIG. 1. FIG.
FIG. 3 is an explanatory diagram of the zoom lens of FIG. 2;
4 is a plan view of a moving plate of each lens support member and a fixed plate of a base member in FIG. 2. FIG.
FIG. 5 is a perspective view of the drive member of FIG. 2;
6 is a cross-sectional view taken along line VI-VI in FIG.
7 is an explanatory diagram of a method for attaching a lens group of the optical unit in FIG. 2. FIG.
FIG. 8 is a perspective view of a main part of a driving member according to a second embodiment of the present invention.
FIG. 9 is a perspective view of a main part of a driving member according to a third embodiment of the present invention.
FIG. 10 is a perspective view of main parts of a drive member according to a fourth embodiment of the present invention.
FIG. 11 is a perspective view of a main part of a driving device using a conventional linear actuator.
[Explanation of symbols]
1 Digital camera
2 Housing
2a, 2b side
2c top surface
3 Shooting window
4 Optical unit
5 Exposure adjustment lever
6 LCD monitor
8 Circuit board
9 Rechargeable battery
10 First unit
11 Zoom curve
12 First lens group
14 First lens support member
15 Lens support (lens frame)
16 Moving board
16a lower edge
16b protrusion
16c cutout
16d surrounding
16s, 16t holding plate
16x, 16y, 16z moving plate
17 Escape hole
18 Straight guide hole
19 Straight guide hole
20 Second unit
21 Zoom curve
22 Second lens group
24 Second lens support member
25 Lens support (lens frame)
26 Moving board
27 Cam hole (second drive means)
28 Straight guide hole
29 Straight guide hole
30 3rd unit
31 Zoom curve
32 Third lens group
34 Third lens support member
35 Lens support (lens frame)
36 Moving board
37 Cam hole (second drive means)
38 Straight guide hole
39 Straight guide hole
40 4th unit
41 Zoom curve
42 Fourth lens group
44 Fourth lens support member
45 Lens support (lens frame)
46 Moving board
47 Cam hole (second drive means)
48 Straight guide hole
49 Straight guide hole
50 base unit
52 Low-pass filter
54 Base member
55 Low-pass filter support
56 Fixing plate
57 Cam hole (second drive means)
58 Straight guide pin
59 Straight guide pin
60 Interlocking bar (second drive means)
61 One end
62 Interlocking pin
64 Retaining spring
70, 70x, 70y, 70z Drive member (drive means, first drive means, linear actuator)
72 fixed part
74 Multilayer piezoelectric element (electromechanical transducer)
74a Bottom
74b side view
74c top view
76,76x, 76y, 76z engaging member
77 Fixed wall
78 Support wall
78a Bottom piece (first piece)
78b Side piece (second piece)
78c Upper piece (second piece)
78d Standing piece (third piece)
78e Protruding part (friction engaging part)
78s side piece (first piece)
78t wing piece (second piece)
78v Protrusion (friction engagement part)
78w Narrow space
78x support wall
78y, 78z Support wall (engagement piece)
80 Main switch
81 Zoom switch
82 Shutter button
88 External power supply terminal
89 Serial output terminal
90 CCD elements
92 CCD support
100 Lens gripper
102 Floodlight
103 Receiver
104 Adhesive injector
106 Optical axis

Claims

An electromechanical transducer that generates a displacement corresponding to the electrical signal by giving a predetermined electrical signal; and an engagement member fixed to one end surface of the electromechanical transducer in the displacement direction. While the member frictionally engages the driven member, the other end surface in the displacement direction of the electromechanical conversion element is supported by the fixed member, and a voltage is applied to the electromechanical conversion element to expand and contract the electromechanical conversion element. In a linear actuator that moves the driven member by sliding and feeding in a friction engagement portion between the engaging member and the driven member,
The engaging member is
A fixed wall portion fixed to the one end surface of the electromechanical conversion element, and a support wall portion integrally formed and connected to the periphery of the fixed wall portion and extending substantially along the side surface of the electromechanical conversion element And a friction engagement portion supported on the side of the electromechanical transducer by the support wall,
The support wall portion includes a first piece extending along a side surface of the electromechanical transducer in a substantially right-angle direction from one side of the peripheral edge of the fixed wall portion, and one side of the peripheral edge of the fixed wall portion. Along the side surface of the electromechanical transducer element, from a pair of sides of the first piece extending substantially at right angles to the opposite side of the first piece, with the electromechanical transducer element sandwiched between the pair of sides. A pair of second pieces extending from each end of the pair of second pieces opposite to the first piece across the electromechanical conversion element, with respect to the electromechanical conversion element. the first piece to be substantially parallel to protrude from one another in the opposite direction, as the frictional engagement portion, and a pair of third piece for holding the driven member, characterized in that, Linear actuator.

An electromechanical transducer that generates a displacement corresponding to the electrical signal by giving a predetermined electrical signal; and an engagement member fixed to one end surface of the electromechanical transducer in the displacement direction. While the member frictionally engages the driven member, the other end surface in the displacement direction of the electromechanical conversion element is supported by the fixed member, and a voltage is applied to the electromechanical conversion element to expand and contract the electromechanical conversion element. In a linear actuator that moves the driven member by sliding and feeding in a friction engagement portion between the engaging member and the driven member,
The engaging member is
A fixed wall portion fixed to the one end surface of the electromechanical transducer, a support wall portion integrally formed on the periphery of the fixed wall portion and extending substantially along the side surface of the electromechanical transducer; A friction engagement portion integrally formed so as to be supported to the side of the electromechanical conversion element by a support wall portion,
The support wall portion is substantially at right angles from one side of the peripheral edge of the upper Symbol fixed wall portion, a first strip extending along a side surface of the electro-mechanical conversion element, into the one side of the peripheral edge of the fixed wall portion A second piece extending substantially at a right angle from one of a pair of sides of the first piece extending substantially at right angles to the electromechanical conversion element, both sides, as the frictional engagement portion, characterized in that it is sandwiched clamping portion provided in the driven member, Linear actuator.

An electromechanical transducer that generates a displacement corresponding to the electrical signal by giving a predetermined electrical signal; and an engagement member fixed to one end surface of the electromechanical transducer in the displacement direction. While the member frictionally engages the driven member, the other end surface in the displacement direction of the electromechanical conversion element is supported by the fixed member, and a voltage is applied to the electromechanical conversion element to expand and contract the electromechanical conversion element. In a linear actuator that moves the driven member by sliding and feeding in a friction engagement portion between the engaging member and the driven member,
The engaging member is
A fixed wall portion fixed to the one end surface of the electromechanical transducer, a support wall portion integrally formed on the periphery of the fixed wall portion and extending substantially along the side surface of the electromechanical transducer; A friction engagement portion integrally formed so as to be supported to the side of the electromechanical conversion element by a support wall portion,
The support wall portion is composed of a pair of engagement pieces extending substantially perpendicularly along a side surface of the electromechanical transducer from a pair of opposite sides of the peripheral edge of the fixed wall portion. the aforementioned electromechanical transducer pieces each outer surface of the opposite side, as the frictional engagement portion, characterized in that it is sandwiched clamping portion provided in the driven member, Linear actuator.

An electromechanical transducer that generates a displacement corresponding to the electrical signal by giving a predetermined electrical signal; and an engagement member fixed to one end surface of the electromechanical transducer in the displacement direction. While the member frictionally engages the driven member, the other end surface in the displacement direction of the electromechanical conversion element is supported by the fixed member, and a voltage is applied to the electromechanical conversion element to expand and contract the electromechanical conversion element. In a linear actuator that moves the driven member by sliding and feeding in a friction engagement portion between the engaging member and the driven member,
The engaging member is
A fixed wall portion fixed to the one end surface of the electromechanical transducer, a support wall portion integrally formed on the periphery of the fixed wall portion and extending substantially along the side surface of the electromechanical transducer; A friction engagement portion integrally formed so as to be supported to the side of the electromechanical conversion element by a support wall portion,
The support wall portion extends at right angles along the side surface of the electromechanical conversion element from a pair of opposite sides of the peripheral edge of the fixed wall portion, and the pair of side edges of the fixed wall portion and substantially parallel to protrude to one another on both sides beyond the side surface of the electro-mechanical conversion element in the extending direction, as the frictional engagement portion, characterized in that it comprises a pair of engaging pieces for holding the driven member, Li Near actuator.