JP3965755B2

JP3965755B2 - Zoom lens barrel

Info

Publication number: JP3965755B2
Application number: JP01203698A
Authority: JP
Inventors: 洋谷岡; 均今成
Original assignee: Nikon Corp
Current assignee: Nikon Corp
Priority date: 1998-01-06
Filing date: 1998-01-06
Publication date: 2007-08-29
Anticipated expiration: 2018-01-06
Also published as: JPH11194256A

Description

【０００１】
【発明の属する技術分野】
本発明は、カメラ等に装着されるズームレンズ鏡筒に係り、詳しくは、その複雑化や強度低下等を防止しながら、前部に位置した固定レンズ群を確実に支持する技術に関する。
【０００２】
【従来の技術】
カメラには、単焦点レンズやズームレンズを始めとして、種々の形式のレンズ鏡筒が装着される。レンズ鏡筒は、一枚あるいは複数枚の光学レンズからなるレンズ群を複数有しており、撮影者（あるいは、カメラ自体）が各レンズ群間の距離を適宜変動させることにより、フォーカシングやズーミングが行われる。そのため、レンズ鏡筒には、各レンズ群の保持に供される複数の筒状部品や、これら筒状部品を光軸に沿って前後動させるカム機構等が内蔵されている。また、レンズ鏡筒は、その外観が一般に円筒形状であるため、外殻やレンズ群を保持するレンズ群保持部材も円状部品あるは環状部品となることが多い。筒状部品や環状部品の素材としては、アルミニウム等の軽金属の他、種々の合成樹脂が用いられ、一般に、前者はダイカスト成形で製作され、後者は射出成形で製作される。
【０００３】
レンズ鏡筒では、被写体を正しく結像させるために各レンズ群を正立状態で保持することが重要となるが、光軸方向に移動するレンズ群（移動レンズ群）を保持するレンズ群保持部材を倒れなく移動させることは容易ではなかった。そこで、実開昭６１−９９８１２号公報には、固定筒の内周面にそれぞれの外周面を摺動自在に嵌合・摺接させることでレンズ群保持部材の倒れを防止し、固定筒の外側に配置されたズームカム環のカム溝に１本または２本のフォロアピンを係合させることでレンズ群保持部材の駆動を行うものが記載されている。また、レンズ群保持部材に３本のフォロアピンを植設し、これらフォロアピンをズームカム環のカム溝に係合させることで、固定筒とレンズ群保持部材とを摺接させることなくレンズ群保持部材を支持する方法も公知である。更に、特開平８−３３４６６５号公報には、レンズ群保持部材間に直進キーと直進溝とによるガイド機構を設け、このガイド機構によりレンズ群保持部材を支持するものが記載されている。
【０００４】
【発明が解決しようとする課題】
上述した従来のレンズ鏡筒では、光軸方向に移動しないレンズ群（固定レンズ群）を有する場合、その支持はいずれも固定筒に固着されたレンズ群保持部材によりなされる。そのため、固定レンズ群をレンズ鏡筒の前部に位置させようとすると、固定筒を鏡筒前部まで延設させなければならず、固定筒の長大化やそれに伴うレンズ鏡筒の重量増大が避けられなかった。また、固定筒を鏡筒前部まで延設させた場合、前部に位置した固定レンズ群と固定筒のマウント側との間には、移動レンズ群を保持するレンズ群保持部材の他、その駆動に供されるカム環やフォロアピン等が配設されるため、固定筒やカム環等に種々の切欠きや逃げ穴等を形成しなければならず、レンズ鏡筒の設計や強度確保が困難になる問題があった。
本発明は上記状況に鑑みなされたもので、その複雑化や強度低下等を防止しながら、前部に位置する固定レンズ群の確実な支持を図ったズームレンズ鏡筒を提供することを目的とする。
【０００５】
【課題を解決する手段】
上記課題を解決するために、請求項１の発明では、マウントに対して固定される固定筒と、この固定筒に対して回動自在に係合すると共に、該固定筒に対して光軸方向の移動が規制されるズーム環と、このズーム環と連動して回動すると共に、前記固定筒に対して光軸方向の移動が規制されるズームカム環と、前記固定筒に対して光軸方向に移動するレンズ群を保持する第１のレンズ群保持部材と、前記固定筒に対して光軸方向に移動しないレンズ群を保持する第２のレンズ群保持部材とを備えたズームレンズ鏡筒において、前記第１のレンズ群保持部材と前記第２のレンズ群保持部材とが光軸方向に相対移動自在に嵌合し、かつ、該第２のレンズ群保持部材と前記ズームカム環との間に回動のみ許容する係止手段を有し、前記固定筒が備えられた部分は、前記係止手段よりも前記マウント側であるものを提案する。この発明によれば、固定筒に対して進退しないズームカム環に第２のレンズ群保持部材が回動自在に支持されるため、固定筒を第２のレンズ群保持部材の近傍にまで延設する必要がなくなる。請求項２の発明では、マウントに対して固定される固定筒と、この固定筒に対して回動自在に係合すると共に、該固定筒に対して光軸方向の移動が規制されるズーム環と、このズーム環と連動して回動すると共に、前記固定筒に対して光軸方向の移動が規制されるズームカム環と、前記固定筒に対して光軸方向に移動するレンズ群を保持する第１のレンズ群保持部材と、前記固定筒に対して光軸方向に移動しないレンズ群を保持する第２のレンズ群保持部材とを備えたズームレンズ鏡筒において、前記第１のレンズ群保持部材と前記第２のレンズ群保持部材とが光軸方向に相対移動自在に嵌合し、かつ、該第２のレンズ群保持部材と前記ズームカム環との間に回動のみ許容する係止手段を有し、前記固定筒が備えられた部分は、前記第２のレンズ群保持部材に保持された前記レンズ群よりも前記マウント側であるものを提案する。請求項３の発明では、請求項１のズームレンズ鏡筒において、前記固定筒が備えられた部分は、前記第２のレンズ群保持部材に保持された前記レンズ群よりも前記マウント側であるものを提案する。
【０００６】
また、請求項４の発明では、請求項１〜３のズームレンズ鏡筒において、前記係止手段は、前記ズームカム環に形成された環状溝と、前記第２のレンズ群保持部材に形成されて該環状溝に係合するフォロアであるものを提案する。この発明によれば、ズームカム環および第２のレンズ群保持部材の加工が比較的容易に行える他、ズームカム環による第２のレンズ群保持部材の支持が確実に行われる。
【０００７】
また、請求項５の発明では、請求項４のズームレンズ鏡筒において、前記ズームカム環には、前記第２のレンズ群保持部材に形成されたフォロアを前記環状溝に導く導入溝が形成されたものを提案する。この発明によれば、例えば、フォロアをズームカム環の通常の回動範囲外で導入溝と一致するように配置すれば、ズームカム環と第２のレンズ群保持部材との組立が容易に行える。
【０００８】
また、請求項６の発明では、請求項１〜５のズームレンズ鏡筒において、前記第１のレンズ群保持部材と前記第２のレンズ群保持部材とは、どちらか一方に形成された直進キーが他方に形成された直進溝に摺動自在に嵌合しているものを提案する。この発明によれば、第１のレンズ群保持部材と前記第２のレンズ群保持部材とが互いに倒れることなく支持しあうため、移動レンズ群と固定レンズ群とが正立しやすくなる。請求項７の発明では、請求項１〜６のいずれか一項に記載のズームレンズ鏡筒において、前記固定筒が備えられた部分は、前記ズームカム環の少なくとも一部よりも前記マウント側であるものを提案する。請求項８の発明では、請求項１〜７のいずれか一項に記載のズームレンズ鏡筒において、前記第１のレンズ群保持部材に保持された前記レンズ群は、前記第２のレンズ群保持部材に保持された前記レンズ群よりも前記マウント側であるものを提案する。
【０００９】
【発明の実施の形態】
以下、本発明の一実施形態を図面に基づき説明する。図１は、本発明の一実施形態に係るズームレンズ鏡筒の縦断面図であり、図２は図１中のＡ−Ａ要部断面図であり、図３は図１中のＢ−Ｂ要部断面図であり、図４は実施形態に係る主要部品の展開図である。図５は実施形態の作用を示す説明図である。
図１において、符号１で示された部材は、カメラ（図示せず）に装着される段付円筒形状の固定マウントであり、その外周面には複数個のバヨネットラグ２が形成されている。固定マウント１の前面には、円筒形状の固定筒３がねじ締結により固着・一体化されている。また、固定マウント１には、その前端にズーム環５が回動自在に支持されており、固定マウント１の内周面の一部に形成された案内突起７がズーム環５の外周面に形成された案内溝９に係合することで、ズーム環５が所定の角度範囲で回動可能となっている。図中、符号Ｌは被写体からの光の進行中心となる光軸であり、ズーム環５等の回動部品は光軸Ｌを中心として回動する。
【００１０】
固定筒３の内側には円筒形状のズームカム環１１が配設されており、ズーム環５に形成された連結溝１３にズームカム環１１に植設された連動ピン１５が係合することで、ズーム環５とズームカム環１１とが一体に回動する。また、ズームカム環１１の後端外周面には環状突起１７が形成されており、この環状突起１７が固定筒３の内周面に形成された前後部係止環１９，２１により挟まれることで、ズームカム環１１の光軸Ｌ方向への移動が防止される。尚、環状突起１７と前部係止環１９とには、それぞれに分解組立用の切欠が形成されているが、煩雑になるため詳細な説明を省略する。
【００１１】
鏡筒内には、前方から後方に向けて、第１レンズ群３０を保持する第１レンズ群保持部材３１と、第２レンズ群３２を保持する第２レンズ群保持部材３３と、第３レンズ群３４を保持する第３レンズ群保持部材３５と、第４レンズ群３６を保持する第４レンズ群保持部材３７と、第５レンズ群３８を保持する第５レンズ群保持部材３９とが配設されている。本実施形態の場合、各レンズ群３０，３２，３４，３６，３８のうち、第２レンズ群３２のみが固定レンズ群であり、他は移動レンズ群である。
【００１２】
図２〜図４に示したように、第５レンズ群保持部材３９はズームカム環１１の内周側に遊嵌し、第４レンズ群保持部材３７は第５レンズ群保持部材３９の内周側に遊嵌し、更に、第３レンズ群保持部材３５は第４レンズ群保持部材３７の内周側に遊嵌している。第５レンズ群保持部材３９は、その外周面に１８０゜間隔で２本のフォロアピン４１が植設されており、これらフォロアピン４１がズームカム環１１に形成された第１カム溝４３に係合している。また、第４レンズ群保持部材３７も、その外周面に１８０゜間隔で２本のフォロアピン４５が植設されており、これらフォロアピン４５がズームカム環１１に形成された第２カム溝４７に係合している。更に、第３レンズ群保持部材３５は、その外周面に１８０゜間隔で２本のフォロアピン４９が植設されており、これらフォロアピン４９がズームカム環１１に形成された第３カム溝５１に係合している。
【００１３】
第５レンズ群保持部材３９は、外周面のフォロアピン４１が固定筒３に形成された直進案内溝５２に係合しているため、固定筒３との相対回動が規制される。また、第４レンズ群保持部材３７は、その外周面に９０゜間隔で２組４本の直進キー５３，５５が形成されており、これら直進キー５３，５５が第５レンズ群保持部材３９の内周面に形成された２組４本の直進溝５７，５９に摺動自在に嵌合しているため、第５レンズ群保持部材３９との相対回動が規制される。更に、第３レンズ群保持部材３５は、その外周面に９０゜間隔で２組４本の直進キー６１，６３が形成されており、これら直進キー６１，６３が第４レンズ群保持部材３７の内周面に形成された２組４本の直進溝６５，６７に摺動自在に嵌合しているため、第４レンズ群保持部材３７との相対回動が規制される。したがって、第３〜第５レンズ群保持部材３５，３７，３９は、いずれも、固定筒３との相対回動が規制され、光軸Ｌに沿ってのみ移動する。尚、第４レンズ群保持部材３７では、外周面側の直進キー５３，５５と内周面側の直進溝６５，６７とが同位置に形成されており、該部の肉厚が他の部位と略同等となっている。
【００１４】
さて、第２レンズ群保持部材３３は、その先端部に放射状に３本のフォロアピン６９が植設されており、これらフォロアピン６９がズームカム環１１の先端側内周面に形成された環状溝７１に係合している。また、第２レンズ群保持部材３３は、その外周面に９０゜間隔で２組４本の直進キー７３，７５が形成されており、第３レンズ群保持部材３５と同様に、これら直進キー７３，７５が第４レンズ群保持部材３７の直進溝６５，６７に摺動自在に嵌合しているため、第４レンズ群保持部材３７との相対回動が規制される。したがって、第２レンズ群保持部材３３は、ズームカム環１１が回動しても、第４レンズ群保持部材３７（すなわち、固定筒３）と相対回動せず、かつ光軸Ｌ方向にも移動しない。尚、ズームカム環１１には、環状溝７１に連続するかたちで前方が開口した３本の導入溝７７が形成されており、組立時においては環状溝７１にフォロアピン６９を導入可能であるが、フォロアピン６９と導入溝７７との位相はズームカム環１１の通常回動範囲内では一致しない。
【００１５】
一方、第５レンズ群保持部材３９の先端部外周面には雄ヘリコイドねじ８１が形成される一方、第１レンズ群保持部材３１の内周面には雌ヘリコイドねじ８３が形成されており、これら雄ヘリコイドねじ８１と雌ヘリコイドねじ８３とが螺合している。ズーム環５と第１レンズ群保持部材３１との間にはフォーカス駆動環８５が介装されており、フォーカス駆動環８５の内周面に形成された直進溝８７に第１レンズ群保持部材３１の外周面に形成された直進キー８９が係合することにより、フォーカス駆動環８５と第１レンズ群保持部材３１とが同時に回転する。フォーカス駆動環８５には、その先端部にマニュアル操作に供されるフォーカス環９１が外嵌すると共に、後端部外周面に図示しない駆動ギヤと噛み合うセクタギヤ９３が形成されている。図中、符号９５はフォーカス駆動環８５の後端部内周面に形成された環状突起であり、この環状突起９５が固定筒３の内周面に形成された前後部係止環９７，９９により挟まれることで、フォーカス駆動環８５の光軸Ｌ方向への移動が防止される。
【００１６】
以下、本実施形態の作用を述べる。
被写体に対してズーミングを行う場合、撮影者は、ズーム環５を適宜回動させる。すると、ズーム環５と一体にズームカム環１１が回動し、ズームカム環１１の第１〜第３カム溝４３，４７，５１にフォロアピン４１，４５，４９が係合していることにより、第３〜第５レンズ群保持部材３５，３７，３９が光軸Ｌに沿って進退する。また、第１レンズ群保持部材３１も、ヘリコイドねじ８１，８３を介して連結されているため、第５レンズ群保持部材３９と一体に進退する。
【００１７】
ところがこの際、第２レンズ群保持部材３３は、フォロアピン６９がズームカム環１１の環状溝７１に係合していることにより、前述したように、固定筒３と相対回動せず、かつ光軸Ｌ方向にも移動しない。すなわち、本実施形態では、第２レンズ群保持部材３３は、固定筒３より前方に位置しながら固定筒３との間に相対移動がなく、第２レンズ群保持部材３３に保持された第２レンズ群３２が固定レンズ群となるのである。尚、フォロアピン６９の外径に対する環状溝７１の幅の余裕を小さくすれば、第２レンズ群保持部材３３のがたつきが少なくなり、第２レンズ群３２の確実な支持が可能となる。
【００１８】
被写体に対してマニュアルフォーカシングを行う場合、撮影者は、フォーカス環９１を介してフォーカス駆動環８５を適宜回動させる。すると、第１レンズ群保持部材３１は、直進溝８７および直進キー８９を介してフォーカス駆動環８５と同角度回動し、その雄ヘリコイドねじ８１が第５レンズ群保持部材３９の雌ヘリコイドねじ８３に対して螺進する。これにより、第１レンズ群保持部材３１は、光軸Ｌに沿って雄ヘリコイドねじ８１の螺進した分だけ進退し、マニュアルフォーカシングが実現される。また、オートフォーカシング時には、カメラ側の駆動源に連結した駆動ギヤが回転すると、フォーカス駆動環８５のセクタギヤ９３が駆動ギヤに噛み合っていることから、フォーカス駆動環８５が正逆いずれかの方向に回転する。これにより、マニュアルフォーカシング時と同様に、第１レンズ群保持部材３１が光軸Ｌに沿って進退し、オートフォーカシングが実現される。
【００１９】
次に、第２〜第５レンズ群保持部材３３，３５，３７，３９間における支持形態とその作用について述べる。
本実施形態では、これらレンズ群保持部材３３，３５，３７，３９間の支持は、内側のレンズ群保持部材の外周面に形成された直進キー（例えば、第４レンズ群保持部材３７側の直進キー５３，５５）と、外側のレンズ群保持部材の内周面に形成された直進溝（例えば、第５レンズ群保持部材３９側の直進溝５７，５９）とが摺動自在に嵌合することでなされ、他の部位においては各レンズ群保持部材どうしが遊嵌している。したがって、各レンズ群保持部材の支持状態は、直進キーと直進溝との嵌合状態（両者間の間隙）のみに依存することになり、比較的容易に高い支持精度を得ることが可能になる他、支持精度を向上させるべく行う金型の修正等も比較的容易になる。
【００２０】
一方、各レンズ群保持部材３３，３５，３７，３９は必ずしも同一の素材から製造されないため、例えば、合成樹脂射出成型品のレンズ群保持部材（ここでは、第３レンズ群保持部材３５とする）がアルミ合金ダイカスト成型品のレンズ群保持部材（ここでは、第４レンズ群保持部材３７とする）の内側に位置することもあり、素材の熱膨張率の相違により、外気温の上昇する夏期等においては、第３レンズ群保持部材３５の外径増大量が第４レンズ群保持部材３７の内径増大量より大きくなる。そのため、レンズ群保持部材どうしを摺動自在に嵌合させた従来装置では、嵌合寸法に相対摺動を阻害しないだけのマージンを設ける必要があり、これが支持精度を低下させる要因となっていた。
【００２１】
ところが、本実施形態では、このような状況に至っても、両レンズ群保持部材３５，３７が遊嵌しているため、第３レンズ群保持部材３５の外周面と第４レンズ群保持部材３７の内周面とは当接しない。この場合、図５に示したように、第３レンズ群保持部材３５側の直進キー６１，６３が第４レンズ群保持部材３７側の直進溝６５，６７内に若干侵入することになるが、直進溝６５，６７の深さ寸法に所定のマージンがとられているため、両レンズ群保持部材３５，３７間の相対摺動には影響がない。
【００２２】
以上述べたように、本実施形態のズームレンズ鏡筒では、ズームカム環１１を介して第２レンズ群保持部材３３を保持するようにしたため、第２レンズ群３２を鏡筒の前方に配置しながら、固定筒３を徒に延設する必要がなくなると共に、固定筒３や他のレンズ群保持部材３５，３７，３９等の形状を簡素なものとすることができた。また、レンズ群保持部材３３，３５，３７，３９間の支持を、内側のレンズ群保持部材の外周面に形成された直進キーと、外側のレンズ群保持部材の内周面に形成された直進溝とを嵌合させることにより行わせるようにしたため、レンズ群保持部材の製造が容易になると同時に、各レンズ群保持部材３５，３７，３９の支持精度も向上させることができた。
【００２３】
以上で具体的実施形態の説明を終えるが、本発明の態様はこの実施形態に限られるものではない。例えば、上記実施形態では、固定側レンズ群保持部材（第２レンズ群保持部材）に植設したフォロアピンをズームカム環に形成した環状溝に係合させるようにしたが、固定側レンズ群保持部材の外周面に環状溝を形成し、この環状溝にズームカム環の内周に突設した係合突起を係合させるようにしてもよい。また、上記実施形態では、各レンズ群保持部材３３，３５，３７，３９間の支持に供される直進キーと直進溝とを各々４本としたが、３本あるいは５本以上としてもよい。また、上記実施形態は、本発明を５群のレンズ群から構成されたズームレンズ鏡筒に適用したものであるが、４群以下あるいは６群以上のレンズ群から構成されるズームレンズ鏡筒に適用してもよい。更に、ズーム機構やフォーカス機構の具体的構成等についても、上記実施形態での例示に限られるものではなく、設計上の都合等により適宜変更可能である。
【００２４】
【発明の効果】
本発明によれば、マウントに対して固定される固定筒と、この固定筒に対して回動自在に係合すると共に、該固定筒に対して光軸方向の移動が規制されるズーム環と、このズーム環と連動して回動すると共に、前記固定筒に対して光軸方向の移動が規制されるズームカム環と、前記固定筒に対して光軸方向に移動するレンズ群を保持する第１のレンズ群保持部材と、前記固定筒に対して光軸方向に移動しないレンズ群を保持する第２のレンズ群保持部材とを備えたズームレンズ鏡筒において、前記第１のレンズ群保持部材と前記第２のレンズ群保持部材とが光軸方向に相対移動自在に嵌合し、かつ、該第２のレンズ群保持部材と前記ズームカム環との間に回動のみ許容する係止手段が形成されたものとしたため、固定筒に対して進退しないズームカム環に第２のレンズ群保持部材が回動自在に支持されるため、固定筒を第２のレンズ群保持部材の近傍にまで延設する必要がなくなると共に、固定筒や各レンズ群保持部材の形状の簡素化により製造が容易になる。
【図面の簡単な説明】
【図１】本発明の一実施形態に係るズームレンズ鏡筒の縦断面図である。
【図２】図１中のＡ−Ａ断面図である。
【図３】図１中のＢ−Ｂ断面図である。
【図４】実施形態に係る主要部品の展開図である。
【図５】実施形態の作用を示す説明図である。
【符号の説明】
３‥‥固定筒
５‥‥ズーム環
１１‥‥ズームカム環
３１‥‥第１レンズ群保持部材
３３‥‥第２レンズ群保持部材
３５‥‥第３レンズ群保持部材
３７‥‥第４レンズ群保持部材
３９‥‥第５レンズ群保持部材
４１‥‥フォロアピン
４３‥‥第１カム溝４３
４５‥‥フォロアピン
４７‥‥第２カム溝
４９‥‥フォロアピン
５１‥‥第３カム溝５１
５２‥‥直進案内溝
５３，５５‥‥直進キー
５７，５９‥‥直進溝
６１，６３‥‥直進キー
６５，６７‥‥直進溝
６９‥‥フォロアピン
７１‥‥環状溝
７３，７５‥‥直進溝
Ｌ‥‥光軸[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a zoom lens barrel mounted on a camera or the like, and more particularly to a technique for reliably supporting a fixed lens group positioned at the front while preventing complication and strength reduction.
[0002]
[Prior art]
Various types of lens barrels such as a single focus lens and a zoom lens are mounted on the camera. The lens barrel has a plurality of lens groups including one or a plurality of optical lenses, and focusing and zooming can be performed by the photographer (or the camera itself) appropriately changing the distance between the lens groups. Done. For this reason, the lens barrel incorporates a plurality of cylindrical parts used for holding each lens group, a cam mechanism for moving these cylindrical parts back and forth along the optical axis, and the like. Further, since the lens barrel is generally cylindrical in appearance, the lens group holding member for holding the outer shell and the lens group is often a circular part or an annular part. As a material for the cylindrical part and the annular part, various synthetic resins are used in addition to a light metal such as aluminum. Generally, the former is manufactured by die casting and the latter is manufactured by injection molding.
[0003]
In a lens barrel, it is important to hold each lens group in an upright state in order to correctly form an object, but a lens group holding member that holds a lens group (moving lens group) that moves in the optical axis direction. It wasn't easy to move it without falling down. Therefore, Japanese Utility Model Laid-Open No. 61-99812 discloses that the outer peripheral surface of the fixed cylinder is slidably fitted and slidably contacted with the inner peripheral surface of the fixed cylinder to prevent the lens group holding member from falling down. A lens unit holding member is driven by engaging one or two follower pins with a cam groove of a zoom cam ring arranged outside. In addition, three follower pins are implanted in the lens group holding member, and these follower pins are engaged with the cam grooves of the zoom cam ring, so that the lens group holding member can be mounted without sliding the fixed tube and the lens group holding member. Supporting methods are also known. Further, Japanese Patent Application Laid-Open No. 8-334665 discloses a structure in which a guide mechanism using a straight key and a straight groove is provided between lens group holding members, and the lens group holding member is supported by this guide mechanism.
[0004]
[Problems to be solved by the invention]
When the conventional lens barrel described above has a lens group (fixed lens group) that does not move in the optical axis direction, the support is made by a lens group holding member fixed to the fixed cylinder. Therefore, if the fixed lens group is positioned at the front part of the lens barrel, the fixed cylinder must be extended to the front part of the lens barrel, which increases the length of the fixed cylinder and the accompanying increase in the weight of the lens barrel. It was inevitable. In addition, when the fixed tube is extended to the front of the lens barrel, in addition to the lens group holding member for holding the moving lens group, the fixed lens group positioned at the front and the mount side of the fixed tube Since cam rings and follower pins are provided for driving, various notches and relief holes must be formed in the fixed cylinder and cam ring, etc., making it difficult to design and secure the strength of the lens barrel. There was a problem to become.
The present invention has been made in view of the above situation, and an object of the present invention is to provide a zoom lens barrel that reliably supports a fixed lens group located in the front portion while preventing its complication and strength reduction. To do.
[0005]
[Means for solving the problems]
In order to solve the above-mentioned problem, in the invention of claim 1, a fixed cylinder fixed to the mount, and rotatably engaged with the fixed cylinder, the optical axis direction with respect to the fixed cylinder A zoom ring that restricts movement of the zoom ring, a zoom cam ring that rotates in conjunction with the zoom ring, and that restricts movement in the optical axis direction relative to the fixed cylinder, and an optical axis direction relative to the fixed cylinder In a zoom lens barrel, comprising: a first lens group holding member that holds a lens group that moves in a moving direction; and a second lens group holding member that holds a lens group that does not move in the optical axis direction with respect to the fixed cylinder. The first lens group holding member and the second lens group holding member are fitted so as to be relatively movable in the optical axis direction, and between the second lens group holding member and the zoom cam ring. has a locking means for permitting only rotation, the fixed cylinder is provided Portion proposes what is the mounting side of the locking means. According to the present invention, since the second lens group holding member is rotatably supported by the zoom cam ring that does not advance and retreat with respect to the fixed cylinder, the fixed cylinder is extended to the vicinity of the second lens group holding member. There is no need. According to a second aspect of the present invention, a fixed cylinder fixed to the mount, and a zoom ring that is rotatably engaged with the fixed cylinder and is restricted from moving in the optical axis direction with respect to the fixed cylinder. And a zoom cam ring that rotates in conjunction with the zoom ring and is restricted from moving in the optical axis direction relative to the fixed cylinder, and a lens group that moves in the optical axis direction relative to the fixed cylinder. A zoom lens barrel comprising: a first lens group holding member; and a second lens group holding member that holds a lens group that does not move in the optical axis direction with respect to the fixed cylinder. A locking means for fitting a member and the second lens group holding member so as to be relatively movable in the optical axis direction, and allowing only rotation between the second lens group holding member and the zoom cam ring. The portion provided with the fixed cylinder has the second label. Than the lens group held in's group holding member proposes what is the mounting side. According to a third aspect of the present invention, in the zoom lens barrel according to the first aspect, the portion provided with the fixed barrel is closer to the mount than the lens group held by the second lens group holding member. Propose.
[0006]
According to a fourth aspect of the present invention, in the zoom lens barrel according to the first to third aspects, the locking means is formed in an annular groove formed in the zoom cam ring and in the second lens group holding member. A follower that engages with the annular groove is proposed. According to the present invention, the zoom cam ring and the second lens group holding member can be processed relatively easily, and the second lens group holding member is reliably supported by the zoom cam ring.
[0007]
According to a fifth aspect of the present invention, in the zoom lens barrel of the fourth aspect , the zoom cam ring is formed with an introduction groove that guides a follower formed in the second lens group holding member to the annular groove. Suggest a thing. According to the present invention, for example, if the follower is disposed so as to coincide with the introduction groove outside the normal rotation range of the zoom cam ring, the zoom cam ring and the second lens group holding member can be easily assembled.
[0008]
Further, in the invention of claim 6, in the zoom lens barrel according to claim 5, wherein the first lens group holding member and the second lens group holding member, linear key formed to either Is proposed to be slidably fitted in a straight groove formed on the other side. According to this invention, since the first lens group holding member and the second lens group holding member support each other without falling down, the movable lens group and the fixed lens group are easily erected. According to a seventh aspect of the present invention, in the zoom lens barrel according to any one of the first to sixth aspects, the portion provided with the fixed barrel is closer to the mount than at least a portion of the zoom cam ring. Suggest a thing. The zoom lens barrel according to any one of claims 1 to 7, wherein the lens group held by the first lens group holding member is held by the second lens group. A lens that is closer to the mount than the lens group held by a member is proposed.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a zoom lens barrel according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the line AA in FIG. 1, and FIG. 3 is a sectional view taken along line BB in FIG. FIG. 4 is a development view of main components according to the embodiment. FIG. 5 is an explanatory diagram showing the operation of the embodiment.
In FIG. 1, a member denoted by reference numeral 1 is a stepped cylindrical fixed mount attached to a camera (not shown), and a plurality of bayonet lugs 2 are formed on the outer peripheral surface thereof. On the front surface of the fixed mount 1, a cylindrical fixed cylinder 3 is fixed and integrated by screw fastening. A zoom ring 5 is rotatably supported at the front end of the fixed mount 1, and a guide projection 7 formed on a part of the inner peripheral surface of the fixed mount 1 is formed on the outer peripheral surface of the zoom ring 5. The zoom ring 5 can be rotated within a predetermined angular range by engaging with the guide groove 9 formed. In the figure, reference numeral L denotes an optical axis that is a traveling center of light from the subject, and rotating parts such as the zoom ring 5 rotate about the optical axis L.
[0010]
A cylindrical zoom cam ring 11 is disposed inside the fixed cylinder 3, and the interlocking pin 15 implanted in the zoom cam ring 11 is engaged with a connecting groove 13 formed in the zoom ring 5, thereby zooming in. The ring 5 and the zoom cam ring 11 rotate integrally. An annular protrusion 17 is formed on the outer peripheral surface of the rear end of the zoom cam ring 11, and the annular protrusion 17 is sandwiched between front and rear locking rings 19 and 21 formed on the inner peripheral surface of the fixed cylinder 3. The zoom cam ring 11 is prevented from moving in the direction of the optical axis L. Although the annular protrusion 17 and the front locking ring 19 are each provided with a notch for disassembly and assembly, detailed description thereof will be omitted because it becomes complicated.
[0011]
Inside the lens barrel, from the front to the rear, a first lens group holding member 31 that holds the first lens group 30, a second lens group holding member 33 that holds the second lens group 32, and a third lens. A third lens group holding member 35 that holds the group 34, a fourth lens group holding member 37 that holds the fourth lens group 36, and a fifth lens group holding member 39 that holds the fifth lens group 38 are disposed. Has been. In the present embodiment, among the lens groups 30, 32, 34, 36, and 38, only the second lens group 32 is a fixed lens group, and the others are moving lens groups.
[0012]
2 to 4, the fifth lens group holding member 39 is loosely fitted to the inner peripheral side of the zoom cam ring 11, and the fourth lens group holding member 37 is the inner peripheral side of the fifth lens group holding member 39. Furthermore, the third lens group holding member 35 is loosely fitted on the inner peripheral side of the fourth lens group holding member 37. The fifth lens group holding member 39 has two follower pins 41 implanted at 180 ° intervals on the outer peripheral surface thereof, and these follower pins 41 engage with a first cam groove 43 formed in the zoom cam ring 11. Yes. The fourth lens group holding member 37 also has two follower pins 45 implanted at 180 ° intervals on the outer peripheral surface thereof, and these follower pins 45 are engaged with second cam grooves 47 formed in the zoom cam ring 11. is doing. Further, the third lens group holding member 35 has two follower pins 49 planted on the outer peripheral surface thereof at an interval of 180 °, and these follower pins 49 engage with a third cam groove 51 formed in the zoom cam ring 11. is doing.
[0013]
In the fifth lens group holding member 39, the follower pin 41 on the outer peripheral surface is engaged with the rectilinear guide groove 52 formed in the fixed cylinder 3, so that the relative rotation with the fixed cylinder 3 is restricted. Further, the fourth lens group holding member 37 has two sets of four rectilinear keys 53 and 55 formed on the outer peripheral surface thereof at intervals of 90 °, and these rectilinear keys 53 and 55 correspond to the fifth lens group holding member 39. Since the two sets of four rectilinear grooves 57 and 59 formed on the inner peripheral surface are slidably fitted, relative rotation with the fifth lens group holding member 39 is restricted. Further, the third lens group holding member 35 is formed with two sets of four rectilinear keys 61, 63 at 90 ° intervals on the outer peripheral surface thereof, and these rectilinear keys 61, 63 serve as the fourth lens group holding member 37. Since the two sets of four rectilinear grooves 65 and 67 formed on the inner peripheral surface are slidably fitted, the relative rotation with the fourth lens group holding member 37 is restricted. Accordingly, the third to fifth lens group holding members 35, 37, 39 are all restricted only from rotating along the optical axis L with respect to the relative rotation with respect to the fixed cylinder 3. In the fourth lens group holding member 37, the straight advance keys 53, 55 on the outer peripheral surface side and the straight advance grooves 65, 67 on the inner peripheral surface side are formed at the same position. It is almost equivalent.
[0014]
The second lens group holding member 33 has three follower pins 69 radially arranged at the tip thereof, and these follower pins 69 are formed in an annular groove 71 formed on the inner peripheral surface of the zoom cam ring 11. Is engaged. The second lens group holding member 33 has two sets of four linear keys 73 and 75 formed at 90 ° intervals on the outer peripheral surface thereof. Like the third lens group holding member 35, these linear keys 73 are provided. , 75 are slidably fitted in the rectilinear grooves 65, 67 of the fourth lens group holding member 37, so that relative rotation with the fourth lens group holding member 37 is restricted. Therefore, even if the zoom cam ring 11 rotates, the second lens group holding member 33 does not rotate relative to the fourth lens group holding member 37 (that is, the fixed cylinder 3), and also moves in the optical axis L direction. do not do. The zoom cam ring 11 is formed with three introduction grooves 77 that open to the front so as to be continuous with the annular groove 71, and the follower pin 69 can be introduced into the annular groove 71 during assembly. 69 and the introduction groove 77 do not match in the normal rotation range of the zoom cam ring 11.
[0015]
On the other hand, a male helicoid screw 81 is formed on the outer peripheral surface of the tip of the fifth lens group holding member 39, while a female helicoid screw 83 is formed on the inner peripheral surface of the first lens group holding member 31. The male helicoid screw 81 and the female helicoid screw 83 are screwed together. A focus drive ring 85 is interposed between the zoom ring 5 and the first lens group holding member 31, and the first lens group holding member 31 is inserted into a rectilinear groove 87 formed on the inner peripheral surface of the focus drive ring 85. When the linearly-moving key 89 formed on the outer peripheral surface is engaged, the focus drive ring 85 and the first lens group holding member 31 rotate simultaneously. A focus ring 91 for manual operation is fitted on the front end portion of the focus drive ring 85, and a sector gear 93 that meshes with a drive gear (not shown) is formed on the outer peripheral surface of the rear end portion. In the figure, reference numeral 95 denotes an annular projection formed on the inner peripheral surface of the rear end portion of the focus drive ring 85, and this annular projection 95 is formed by front and rear portion locking rings 97 and 99 formed on the inner peripheral surface of the fixed cylinder 3. By being pinched, the movement of the focus drive ring 85 in the direction of the optical axis L is prevented.
[0016]
The operation of this embodiment will be described below.
When zooming the subject, the photographer rotates the zoom ring 5 appropriately. Then, the zoom cam ring 11 is rotated integrally with the zoom ring 5, and the follower pins 41, 45, 49 are engaged with the first to third cam grooves 43, 47, 51 of the zoom cam ring 11. The fifth lens group holding members 35, 37, and 39 advance and retract along the optical axis L. Further, since the first lens group holding member 31 is also connected via the helicoid screws 81 and 83, the first lens group holding member 31 advances and retreats integrally with the fifth lens group holding member 39.
[0017]
However, at this time, the second lens group holding member 33 does not rotate relative to the fixed barrel 3 and has an optical axis as described above because the follower pin 69 is engaged with the annular groove 71 of the zoom cam ring 11. It does not move in the L direction. In other words, in the present embodiment, the second lens group holding member 33 is positioned in front of the fixed cylinder 3 but does not move relative to the fixed cylinder 3, and the second lens group holding member 33 is held by the second lens group holding member 33. The lens group 32 becomes a fixed lens group. If the margin of the width of the annular groove 71 with respect to the outer diameter of the follower pin 69 is reduced, rattling of the second lens group holding member 33 is reduced, and the second lens group 32 can be reliably supported.
[0018]
When performing manual focusing on the subject, the photographer rotates the focus drive ring 85 as appropriate through the focus ring 91. Then, the first lens group holding member 31 is rotated at the same angle as the focus drive ring 85 via the rectilinear groove 87 and the rectilinear key 89, and the male helicoid screw 81 is the female helicoid screw 83 of the fifth lens group holding member 39. Screw against. Thereby, the first lens group holding member 31 moves back and forth along the optical axis L as much as the male helicoid screw 81 is screwed, and manual focusing is realized. During autofocusing, when the drive gear connected to the drive source on the camera side rotates, the sector gear 93 of the focus drive ring 85 meshes with the drive gear, so the focus drive ring 85 rotates in either the forward or reverse direction. To do. As a result, similarly to the manual focusing, the first lens group holding member 31 moves back and forth along the optical axis L, and autofocusing is realized.
[0019]
Next, a support form and its operation between the second to fifth lens group holding members 33, 35, 37 and 39 will be described.
In the present embodiment, the support between the lens group holding members 33, 35, 37, 39 is a linear key formed on the outer peripheral surface of the inner lens group holding member (for example, the straight movement on the fourth lens group holding member 37 side). Keys 53 and 55) and rectilinear grooves formed on the inner peripheral surface of the outer lens group holding member (for example, rectilinear grooves 57 and 59 on the fifth lens group holding member 39 side) are slidably fitted. Thus, the lens group holding members are loosely fitted in other parts. Therefore, the support state of each lens group holding member depends only on the fitting state (gap between both) of the straight key and the straight groove, so that high support accuracy can be obtained relatively easily. In addition, it is relatively easy to modify the mold to improve the support accuracy.
[0020]
On the other hand, since each lens group holding member 33, 35, 37, 39 is not necessarily manufactured from the same material, for example, a lens group holding member of a synthetic resin injection molded product (herein referred to as a third lens group holding member 35). May be located inside the lens group holding member (herein referred to as the fourth lens group holding member 37) of an aluminum alloy die-cast product, and in the summer when the outside temperature rises due to the difference in the coefficient of thermal expansion of the material. , The outer diameter increase amount of the third lens group holding member 35 is larger than the inner diameter increase amount of the fourth lens group holding member 37. Therefore, in the conventional device in which the lens group holding members are slidably fitted to each other, it is necessary to provide a margin that does not hinder the relative sliding in the fitting dimension, and this is a factor that reduces the support accuracy. .
[0021]
However, in this embodiment, even if such a situation is reached, the lens group holding members 35 and 37 are loosely fitted, so that the outer peripheral surface of the third lens group holding member 35 and the fourth lens group holding member 37 are It does not contact the inner peripheral surface. In this case, as shown in FIG. 5, the rectilinear keys 61 and 63 on the third lens group holding member 35 side slightly enter the rectilinear grooves 65 and 67 on the fourth lens group holding member 37 side. Since a predetermined margin is provided for the depth dimension of the rectilinear grooves 65 and 67, the relative sliding between the lens group holding members 35 and 37 is not affected.
[0022]
As described above, in the zoom lens barrel of the present embodiment, since the second lens group holding member 33 is held via the zoom cam ring 11, the second lens group 32 is disposed in front of the lens barrel. Further, it is not necessary to extend the fixed cylinder 3 and the shapes of the fixed cylinder 3 and the other lens group holding members 35, 37, 39 and the like can be simplified. Further, the support between the lens group holding members 33, 35, 37, and 39 is supported by a straight key formed on the outer peripheral surface of the inner lens group holding member and a straight drive formed on the inner peripheral surface of the outer lens group holding member. Since the lens group holding member can be easily manufactured, the support accuracy of the lens group holding members 35, 37, and 39 can be improved.
[0023]
Although description of specific embodiment is finished above, the aspect of the present invention is not limited to this embodiment. For example, in the above embodiment, the follower pin implanted in the fixed side lens group holding member (second lens group holding member) is engaged with the annular groove formed in the zoom cam ring. An annular groove may be formed on the outer peripheral surface, and an engaging protrusion projecting from the inner periphery of the zoom cam ring may be engaged with the annular groove. In the above embodiment, the number of the linearly-advancing keys and the linearly-advancing grooves provided for supporting the lens group holding members 33, 35, 37, and 39 is four, but the number may be three or five or more. In the above embodiment, the present invention is applied to a zoom lens barrel constituted by five lens groups. However, in the zoom lens barrel constituted by four or less lens groups or six or more lens groups. You may apply. Further, the specific configuration of the zoom mechanism and the focus mechanism is not limited to the examples in the above embodiment, and can be appropriately changed depending on the design convenience.
[0024]
【The invention's effect】
According to the present invention, a fixed cylinder fixed to the mount, and a zoom ring that engages with the fixed cylinder in a rotatable manner and is restricted from moving in the optical axis direction with respect to the fixed cylinder. A zoom cam ring that rotates in conjunction with the zoom ring and that is restricted from moving in the optical axis direction with respect to the fixed cylinder, and a lens group that moves in the optical axis direction with respect to the fixed cylinder. A zoom lens barrel comprising: a first lens group holding member; and a second lens group holding member that holds a lens group that does not move in the optical axis direction with respect to the fixed cylinder. And a second lens group holding member are fitted so as to be relatively movable in the optical axis direction, and a locking means that allows only rotation between the second lens group holding member and the zoom cam ring is provided. Because it is formed, it does not move forward and backward with respect to the fixed cylinder. Since the second lens group holding member is rotatably supported by the cam ring, it is not necessary to extend the fixed cylinder to the vicinity of the second lens group holding member, and the fixed cylinder and each lens group holding member The simplification of the shape facilitates manufacturing.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a zoom lens barrel according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
3 is a cross-sectional view taken along the line BB in FIG.
FIG. 4 is a development view of main components according to the embodiment.
FIG. 5 is an explanatory diagram showing the operation of the embodiment.
[Explanation of symbols]
3 ... fixed cylinder 5 ... zoom ring 11 ... zoom cam ring 31 ... first lens group holding member 33 ... second lens group holding member 35 ... third lens group holding member 37 ... fourth lens group holding Member 39 Fifth lens group holding member 41 Follower pin 43 First cam groove 43
45 ... Follower pin 47 ... Second cam groove 49 ... Follower pin 51 ... Third cam groove 51
52 Linear guide groove 53, 55 Linear key 57, 59 Linear groove 61, 63 Linear key 65, 67 Linear groove 69 Follower pin 71 Ring groove 73, 75 Linear groove L ... Optical axis

Claims

A fixed cylinder fixed to the mount;
A zoom ring that engages with the fixed cylinder so as to be rotatable, and is restricted from moving in the optical axis direction relative to the fixed cylinder
A zoom cam ring that rotates in conjunction with the zoom ring and is restricted from moving in the optical axis direction with respect to the fixed cylinder;
A first lens group holding member that holds a lens group that moves in the optical axis direction with respect to the fixed cylinder;
A zoom lens barrel including a second lens group holding member that holds a lens group that does not move in the optical axis direction with respect to the fixed cylinder;
The first lens group holding member and the second lens group holding member are fitted so as to be relatively movable in the optical axis direction, and are rotated between the second lens group holding member and the zoom cam ring. Having locking means that only allow movement ;
The zoom lens barrel characterized in that the portion provided with the fixed barrel is located closer to the mount than the locking means .

  A fixed cylinder fixed to the mount;
A zoom ring that engages with the fixed cylinder so as to be rotatable, and is restricted from moving in the optical axis direction with respect to the fixed cylinder;
  A zoom cam ring that rotates in conjunction with the zoom ring and is restricted from moving in the optical axis direction with respect to the fixed cylinder;
  A first lens group holding member that holds a lens group that moves in the optical axis direction with respect to the fixed cylinder;
  In a zoom lens barrel comprising: a second lens group holding member that holds a lens group that does not move in the optical axis direction with respect to the fixed cylinder;
  The first lens group holding member and the second lens group holding member are fitted so as to be relatively movable in the optical axis direction, and are rotated between the second lens group holding member and the zoom cam ring. Having locking means that only allow movement;
  The zoom lens barrel according to claim 1, wherein the portion provided with the fixed barrel is closer to the mount side than the lens group held by the second lens group holding member.

2. The zoom lens barrel according to claim 1, wherein the portion provided with the fixed cylinder is closer to the mount side than the lens group held by the second lens group holding member.

Said locking means is characterized by an annular groove formed in the zoom cam ring, is formed on the second lens group holding member is a follower that engages into the annular groove, claims 1 to 3 The zoom lens barrel according to any one of the above.

5. The zoom lens barrel according to claim 4 , wherein the zoom cam ring includes an introduction groove that guides a follower formed in the second lens group holding member to the annular groove. 6.

In the first lens group holding member and the second lens group holding member, a straight key formed on one of them is slidably fitted in a straight groove formed on the other. The zoom lens barrel according to any one of claims 1 to 5 .

The zoom lens barrel according to any one of claims 1 to 6, wherein the portion provided with the fixed barrel is closer to the mount than at least a portion of the zoom cam ring.

The lens group held by the first lens group holding member is the second lens group holding part. The zoom lens barrel according to claim 1, wherein the zoom lens barrel is located closer to the mount than the lens group held by a material.