JP4095321B2 - Lens barrel, camera and optical equipment - Google Patents

Description

【００４９】
一方、モーターコントロール回路１１１は、ロジックコントロール回路１１６からの起動信号を受けることによりモーター１０８を正転させて、第１差動カム筒１４２を光軸回りに回転させる。これにより、第１レンズ群および第２レンズ群が、後述するように光軸方向に移動する。
【００５０】
第１差動カム筒１４２の回転は、パルス板１０９によりパルス化されてパルス検出回路１１０に出力されるとともに、パルス検出回路１１０でパルスの検出が行われて、コンパレータ１１２ａに送られる。
【００５１】
モーター１０８の正転により第１差動カム筒１４２が回転し続けている間は、パルス検出回路１１０においてパルスの検出が行われており、パルス数が１１パルス（第１差動カム筒回転演算回路１１３において演算されたコンパレータ１１２ａの基準値）となると、コンパレータ１１２ａが反転することによりモーター１０８の正転を終了させるための信号をモーターコントロール回路１１１に発し、モーターコントロール回路１１１はモーター１０８の両端をショートさせることによりモーター１０８に電気ブレーキをかけてモーター１０８の正転を停止させる。
【００５２】
上述した回路動作により、第１差動カム筒１４２は、固定筒１４１とのヘリコイド係合により光軸回りに回転しながら光軸方向に繰り出す。このとき、第２差動カム筒１４４の駆動ピン１５１は、第１カム溝１４３ｂに案内されて位置１４３ｂ３（∞位置）から位置１４３ｂ４（至近位置）までの間のうちモーター１０８の回転量（第１差動カム筒１４２の回転量）に応じた位置まで移動し、第２差動カム筒１４４を光軸方向に繰り出す。
【００５３】
この第２差動カム筒１４４の繰り出しにより、１群レンズ鏡筒１４５の１群カムピン１４５ａは第２カム溝１４４ｂに案内されて、位置１４４ｂ３（∞位置）から位置１４４ｂ４（至近位置）までの間のうち第２差動カム１４４の繰り出し量に応じた位置まで移動する。これにより、１群レンズ鏡筒１４５が光軸方向に繰り出す。また、２群レンズホルダー１４８の２群カムピン１４８ａは、第３カム溝１４４ｃに案内されて、位置１４４ｃ３（∞位置）から位置１４４ｃ４（至近位置）のうち第２差動カム筒１４４の繰り出し量に応じた位置まで移動する。これにより、２群レンズホルダー１４８が光軸方向に繰り出す。
【００５４】
上述した動作により、１群レンズ鏡筒１４５に保持されている第１レンズ群および２群レンズホルダー１４８に保持されている第２レンズ群がそれぞれ、光軸方向に移動して焦点調節が行われる。
【００５５】
この後、撮影者がレリーズボタンを第２ストロークまで押し込むと、公知の露光動作が行われる。レリーズボタンの押し込みが解除されてレリーズボタンが元の位置に復帰すると、モーターコントロール回路１１１はロジックコントロール回路１１６からの起動信号を受けて、モーター１０８を回転（逆転）させる。これにより、第１差動カム筒１４２が光軸回りに回転して、レンズ鏡筒がＷＩＤＥ待機状態に戻るとともに、レンズ鏡筒がＷＩＤＥ待機状態となった後にスイッチＳＷがオフとなることでコンパレータ１１２ｂが反転して、モーター１０８の回転が停止する。そして、フィルムが一駒分巻き上げられることにより、カメラは撮影前の状態にもどる。
【００５６】
なお、本実施形態においては、ズーム位置をＷＩＤＥ、Ｍ１、Ｍ２、Ｍ３、ＴＥＬＥの５点として倍率切換を行っているが、ズーム位置の数を５点より多くしたり少なくしたりして倍率切換を行うようにしてもよい。
【００５７】
また、本実施形態においては、パルス板１０９およびパルス検出回路１１０を設けて、第１差動カム筒１４２の回転角（第１レンズ群および第２レンズ群の光軸方向における位置関係）を検出することにより、モーター１０８の回転停止時期を決定しているが、これに限るものではなく、モーター１０８にパルスモーターを使用し、第１差動カム筒回転演算回路１１３からの出力パルス数に応じてパルスモーターを回転させて第１差動カム筒１４２を所定の回転角の位置まで回転させるとともに、モーター１０８の回転停止時期を決定してもよい。このようにすれば、第１差動カム筒回転演算回路１１３からの信号を直接モーターコントロール回路１１１に入力すればよいため、カメラ本体１５９内にパルス板１０９、パルス検出回路１１０およびコンパレータ１１２ａを設ける必要がなくなり、カメラの小型化を図ることができる。
【００５８】
次に、レンズ鏡筒が沈胴状態からＴＥＬＥ状態（図４）まで繰り出す際の動作を説明する。
【００５９】
撮影者がズーミング操作部材１１８を操作して、ズーム位置をＴＥＬＥに設定すると、モーター１０８が回転（正転）して、このモーター１０８の回転力が減速ギヤ列（ギヤ１２１を含む）および長軸ギヤ１２０を介して第１差動カム筒１４２に伝達される。これにより、第１差動カム筒１４２は、固定筒１４１とのヘリコイド係合により、光軸回りに回転しながら光軸方向に繰り出す。このとき、第２差動カム筒１４４の駆動ピン１５１は、第１カム溝１４３ｂに案内されて位置１４３ｂ１から位置１４３ｂ１８まで移動する。これにより、第２差動カム筒１４４は第１直進ガイド筒１４３（第１差動カム筒１４２）に対して、光軸回りに回転しながら繰り出す。ここで、第２差動カム筒１４４の繰り出し量は、位置１４３ｂ１から位置４３ｂ１８の間における駆動ピン１５１の光軸方向移動量に相当する。
【００６０】
第２差動カム筒１４４が繰り出されることにより、１群レンズ鏡筒１４５の１群カムピン１４５ａは、第２カム溝１４４ｂに案内されて位置１４４ｂ１から位置１４４ｂ１８まで移動する。これにより、１群レンズ鏡筒１４５は第２差動カム筒１４４に対して、位置１４４ｂ１から位置１４４ｂ１８の間における１群カムピン１４５ａの光軸方向移動量分だけ繰り出される。また、２群レンズホルダー１４８の２群カムピン１４８ａは、第３カム溝１４４ｃに案内されて位置１４４ｃ１から位置１４４ｃ１８まで移動する。これにより、２群レンズホルダー１４８は第２差動カム筒１４４に対して、位置１４４ｃ１から位置１４４ｃ１８の間における２群カムピン１４８ａの光軸方向移動量分だけ繰り出される。上述した動作により、レンズ鏡筒がＴＥＬＥ待機状態となる（図４）。
【００６１】
ＴＥＬＥ待機状態において、撮影者がレリーズボタンを第１ストロークまで押し込むと、ロジックコントロール回路１１６からの出力信号をうけた測距モジュール１１７において測距動作が行われ、測距モジュール１１７により測定された被写体距離に基づいて焦点調節が行われる。焦点調節を行う場合、まずモーター１０８の回転力が第１差動カム筒１４２に伝達され、第１差動カム筒１４２は固定筒１４１とのヘリコイド係合により光軸回りに回転しながら光軸方向に繰り出す。このとき、第２差動カム筒１４４の駆動ピン１５１は第１カム溝１４３ｂに案内されて位置１４３ｂ１９（∞位置）から位置１４３ｂ２０（至近位置）までの間のうちモーター１０８の回転量（第１差動カム筒１４２の回転量）に応じた位置まで移動し、第２差動カム筒１４４を光軸方向に繰り出す。
【００６２】
この第２差動カム筒１４４の繰り出しにより、１群レンズ鏡筒１４５の１群カムピン１４５ａは第２カム溝１４４に案内されて、位置１４４ｂ１９から位置１４４ｂ２０までの間のうち第２差動カム１４４の繰り出し量に応じた位置まで移動する。これにより、１群レンズ鏡筒１４５が光軸方向に繰り出す。また、２群レンズホルダー１４８の２群カムピン１４８ａは、第３カム溝１４４ｃに案内されて、位置１４４ｃ１９（∞位置）から位置１４４ｃ２０（至近位置）までの間のうち第２差動カム筒１４４の繰り出し量に応じた位置まで移動する。これにより、２群レンズホルダー１４８が繰り込む。
【００６３】
上述した動作により、１群レンズ鏡筒１４５に保持されている第１レンズ群および２群レンズホルダー１４８に保持されている第２レンズ群がそれぞれ、光軸方向に移動して焦点調節が行われる。そして、撮影者がレリーズボタンを第２ストロークまで押し込むと、公知の露光動作が行われる。露光終了後、モーター１０８を駆動させることにより、第１差動カム筒１４２を光軸回りに回転させてレンズ鏡筒をＴＥＬＥ待機位置まで繰り込ませるとともに、フィルムの巻き上げが行われる。これにより、フィルムの１駒撮影が完了してカメラが撮影開始前の状態に戻る。
【００６４】
一方、ズーム位置をＭ１、Ｍ２、Ｍ３に切り換えた場合にも、レンズ鏡筒は上述したような倍率切換および焦点調節の動作を行う。
【００６５】
ここで、図６に示すように、ズーム位置がＷＩＤＥからＭ１に切り換わる際、第１カム溝１４３ｂにおけるＷＩＤＥ〜Ｍ１までの領域のリフト量は、他のズーム位置切換領域（Ｍ１〜Ｍ２までの領域、Ｍ２〜Ｍ３までの領域、Ｍ３〜ＴＥＬＥまでの領域）におけるリフト量よりも小さくなっている。つまり、ＷＩＤＥ〜Ｍ１における第２差動カム筒１４４の駆動速度を他のズーム位置切換領域における第２差動カム筒１４４の駆動速度よりも小さくしている。ここで、図８に示すように、第２差動カム筒１４４において、ＷＩＤＥ〜Ｍ１間のレンズ群（第１レンズ群および第２レンズ群）の駆動速度は、他のズーム位置間（Ｍ１〜Ｍ２、Ｍ２〜Ｍ３、Ｍ３〜ＴＥＬＥ）のレンズ群の駆動速度よりも大きくなっているため、ＷＩＤＥ〜Ｍ１間での第２差動カム筒１４４の駆動速度を小さくすることにより、レンズ鏡筒におけるＷＩＤＥ〜Ｍ１間での焦点距離変化速度を小さくしている。これにより、撮影者がファインダーを覗いてＷＩＤＥ〜Ｍ１間で倍率切換を行う場合、違和感を感じることなく倍率切換を行うことができる。
【００６６】
本実施形態のレンズ鏡筒は、連続的なズーミングが不可能であり、５〜６つの焦点距離へとびとびにしかズーミングができない。また、焦点距離を知るセンサの関係上、隣接する焦点距離間でのカム筒の回転角は等しくなっている。ここで、一般的な光学設計を行い、第１群をリニアに繰り出すメカ構造にすると、従来技術のようにＷＩＤＥにおける焦点距離と次のズーム位置における焦点距離との値が大きく離れる。
【００６７】
このため、ＷＩＤＥからＴＥＬＥ側にズーム操作しただけで大きく画角変化し、ファインダを覗いている撮影者に違和感を与えてしまう。しかも、ＷＩＤＥと所定のミドル段との間で停止させることもできない。
【００６８】
そこで、本実施形態のようにＷＩＤＥに隣接するズーム位置（Ｍ１）における焦点距離をＷＩＤＥにおける焦点距離に近づけるようにすることで、視覚的および感覚的に等間隔に近いズーミングが可能となり、撮影者に違和感を与えるのを防止することができる。
【００６９】
また、ＷＩＤＥおよびＴＥＬＥにおける焦点距離は、従来（図１６）のＷＩＤＥおよびＴＥＬＥにおける焦点距離と同じになるように設定しており、ズーム位置がＭ１、Ｍ２、Ｍ３と切り換わるにつれて焦点距離が従来のズーム位置における焦点距離に近づいていく。
【００７０】
（第２実施形態）
次に本発明の第２実施形態であるレンズ鏡筒について図９から図１５を用いて説明する。本実施形態においては、レンズ鏡筒をカメラに備え付けているが、他の光学機器に備え付けてもよい。
【００７１】
図９は本実施形態におけるレンズ鏡筒の分解斜視図である。本実施形態におけるレンズ鏡筒も第１実施形態のレンズ鏡筒と同様に、いわゆる差動カム筒を２つ備えた３段沈胴式レンズ鏡筒である。
【００７２】
２４１はカメラ本体に固定される固定筒であり、この固定筒２４１の内周にはメスヘリコイドが形成されている。
【００７３】
２４２は第１差動カム筒（本願請求項に記載の第１のカム部材）で、第１差動カム筒２４２の内周に光軸方向に延びる直進溝が形成されているとともに、第１差動カム筒２４２の外周後端部２４２ａにオスヘリコイドが形成されている。このオスヘリコイドは固定筒２４１に形成されたメスヘリコイドと係合する。第１差動カム筒２４２は減速ギア列を介してモーター（不図示）と連動しており、第１差動カム筒２４２がモーターの回転力を受けると、固定筒２４１とのヘリコイド係合により光軸回りに回転しながら光軸方向に移動する。
【００７４】
２４３は第１直進ガイド筒であり、第１差動カム筒２４２の内部に、第１差動カム筒２４２の回転に対して摺動可能な状態で保持される。第１直進ガイド筒２４３には第１カム溝が形成されている。また、第１直進ガイド筒２４３の外周後端部には凸部が形成されており、この凸部は固定筒２４１の内周に形成された光軸方向に延びる溝部に係合する。ここで、第１差動カム筒２４２が光軸回りに回転しながら光軸方向に移動すると、第１直進ガイド筒２４３は、凸部が固定筒２４１の溝部に係合しているため、第１差動カム筒２４２と一体となって回転せずに光軸方向にだけ移動する。
【００７５】
２４４は第１直進ガイド筒２４３の内部に組み込まれる第２差動カム筒（本願請求項に記載の第２のカム部材）で、この第２差動カム筒の外周には駆動ピン２５１がはめ込まれる凹部２４４ａが形成されている。凹部２４４ａにはめ込まれた駆動ピン２５１は、第１直進ガイド筒２４３に形成された第１カム溝を貫通して、第１差動カム筒２４２の直進溝に係合する。
【００７６】
２４５は第１レンズ群を保持する１群レンズ鏡筒であり、第２直進ガイド筒２４７の内部に組み込まれる。１群レンズ鏡筒２４５の周方向には３つの１群カムピン２４５ａが形成されており、これらの１群カムピン２４５ａは第２直進ガイド筒２４７に形成された光軸方向に延びる溝部を貫通して、第２差動カム筒２４４の内周に形成された第２カム溝に係合する。
【００７７】
２４６はナットリングであり、第２直進ガイド筒２４７の爪部２４７ａと後端フランジ部２４７ｂとの間に光軸回りに回転可能な状態で取り付けられる。ナットリング２４６の外周には、光軸方向に延びる２つのナット部２４６ａが形成されている。ここで、駆動ピン２５１は、ナット部２４６ａを貫通した状態で第２差動カム筒２４４の凹部２４４ａにはめ込まれる。これにより、第２差動カム筒２４４と第２直進ガイド筒２４７は相対的に回転しながら第１直進ガイド筒２４３（第１差動カム筒２４２）に対して光軸方向に移動する。
【００７８】
２４８は第２レンズ群を保持する２群レンズホルダーであり、第２直進ガイド筒２４７の内部に組み込まれる。ここで、第２レンズ群は、周方向に板バネ２５３を配置した状態で２群レンズホルダー２４８に組み込まれるとともに、固定リング２５４により２群レンズホルダー２４８側に押しつけられて固定される。２群レンズホルダー２４８の周方向には３つの２群カムピン２４８ａがはめ込まれ、これらの２群カムピン２４８ａは第２直進ガイド筒２４７に形成された光軸方向に延びる溝部を貫通して、第２差動カム筒２４４の内周に形成された第３カム溝に係合する。
【００７９】
２４９は撮影光路外の有害光をカットするための第１フレアカット板である。この第１フレアカット板２４９の中央部には撮影光束を通過させるための開口部２４９ａが形成されている。また、第１フレアカット板２４９の周方向には、光軸方向に凸状に形成された係合部２４９ｂが形成されており、この係合部２４９は第１直進ガイド筒２４３の後端フランジ部２４３ａに形成された被係合部（不図示）に係止する。これにより、第１フレアカット板２４９は第１直進ガイド筒２４３と一体となって光軸方向に移動する。
【００８０】
２５０は撮影光路外の有害光をカットするための第２フレアカット板である。この第２フレアカット板２５０の中央部には撮影光束を通過させるための開口部２５０ａが形成されている。また、第２フレアカット板２５０の周方向には被係合部２５０ｂが形成されており、この被係合部２５０ｂには第２直進ガイド筒２４７の後端フランジ部２４７ｂに形成された爪部２４７ｃが係止する。これにより、第２フレアカット板２５０は第２直進ガイド筒２４７と一体となって光軸方向に移動する。
【００８１】
上述した構成において、本実施形態のレンズ鏡筒を備えたカメラの倍率切換および焦点調節の動作を図１０から図１５を用いて説明する。ここで、図１０は沈胴状態におけるレンズ鏡筒の断面図であり、図１１はＷＩＤＥ待機状態におけるレンズ鏡筒の断面図であり、図１２はＴＥＬＥ待機状態におけるレンズ鏡筒の断面図である。また、図１３は第１直進ガイド筒２４３の展開図であり、図１４は第２差動カム筒２４４の展開図であり、図１５は第２差動カム筒２４４の部分展開図である。
【００８２】
まず、レンズ鏡筒の沈胴状態について説明する。レンズ鏡筒が沈胴状態（図１０）にあるとき、固定筒２４１とヘリコイド係合している第１差動カム筒２４２は、固定筒２４１の前面から繰り出していない。第２差動カム筒２４４の駆動ピン２５１は、第１直進ガイド筒２４３に形成された第１カム溝２４３ｂに係合しており、第１カム溝２４３ｂの位置２４３ｂ１にある。
【００８３】
第１レンズ群を保持する１群レンズ鏡筒２４５に形成された１群カムピン２４５ａは、第２差動カム筒２４４に形成された第２カム溝２４４ｂに係合しており、第２カム溝２４４ｂの位置２４４ｂ１にある。このとき、１群レンズ鏡筒２４５は第２差動カム筒２４４に対して繰り出していない。
【００８４】
第２レンズ群を保持する２群レンズホルダー２４８の２群カムピン２４８ａは、第２差動カム筒２４４の内周に形成された第３カム溝２４４ｃに係合しており、第３カム溝２４４ｃの位置２４４ｃ１にある。
【００８５】
次に、レンズ鏡筒が沈胴状態（図１０）からＷＩＤＥ待機状態（図１１）まで繰り出す際の動作を説明する。
【００８６】
撮影者がカメラ本体２５９の電源をオンにするとともに、カメラ本体２５９に備え付けられたズームスイッチ（不図示）を操作してズーム位置をＷＩＤＥに設定すると、モーターが回転し、このモーターの回転力が第１差動カム筒２４２に伝達される。これにより、第１差動カム筒２４２は、固定筒２４１とのヘリコイド係合により、光軸回りに回転しながら光軸方向に繰り出す。このとき、第２差動カム筒２４４に取り付けられた駆動ピン２５１は、第１カム溝２４３ｂに案内されて位置２４３ｂ１から位置２４３ｂ２まで移動する。これにより、第２差動カム筒２４４は第１直進ガイド筒２４３に対して、位置２４３ｂ１から位置２４３ｂ２の間における駆動ピン２５１の光軸方向移動量分だけ繰り出される。
【００８７】
第２差動カム筒２４４が繰り出されることにより、１群レンズ鏡筒２４５の１群カムピン２４５ａは、第２カム溝２４４ｂに案内されて位置２４４ｂ１から位置２４４ｂ２まで移動する。これにより、１群レンズ鏡筒２４５は第２差動カム筒２４４に対して、位置２４４ｂ１から位置２４４ｂ２の間における１群カムピン２４５ａの光軸方向移動量分だけ繰り出される。また、２群レンズホルダー２４８に取り付けられた２群カムピン２４８ａは、第３カム溝２４４ｃに案内されて位置２４４ｃ１から位置２４４ｃ２まで移動する。これにより、２群レンズホルダー２４８は第２差動カム筒２４４に対して、位置２４４ｃ１から位置２４４ｃ２の間における２群カムピン２４８ａの光軸方向移動量分だけ繰り込まれる。上述した動作により、レンズ鏡筒がＷＩＤＥ待機状態となる（図１１）。
【００８８】
ＷＩＤＥ待機状態において、撮影者がレリーズボタンを第１ストロークまで押し込むことにより、カメラ本体２５９内部に備えられた測距部（不図示）により被写体距離が測定され、この被写体距離情報に基づいて焦点調節が行われる。
【００８９】
焦点調節を行う場合、まず、モーターの回転力が第１差動カム筒２４２に伝達され、第１差動カム筒２４２が固定筒２４１とのヘリコイド係合により光軸回りに回転しながら光軸方向に繰り出す。このとき、第２差動カム筒２４４の駆動ピン２５１が、第１カム溝２４３ｂに案内されて位置２４３ｂ３（∞位置）から位置２４３ｂ４（至近位置）までの間のうちモーターの回転量（第１差動カム筒２４２の回転量）に応じた位置まで移動することにより、第２差動カム筒２４４を光軸方向に繰り出す。
【００９０】
この第２差動カム筒２４４の繰り出しにより、１群レンズ鏡筒２４５の１群カムピン２４５ａは第２カム溝２４４ｂに案内されて、位置２４４ｂ３（∞位置）から位置２４４ｂ４（至近位置）までの間のうち第２差動カム２４４の繰り出し量に応じた位置まで移動する。これにより、１群レンズ鏡筒２４５が光軸方向に繰り出す。また、２群レンズホルダー２４８の２群カムピン２４８ａは、第３カム溝２４４ｃに案内されて、位置２４４ｃ３（∞位置）から位置２４４ｃ４（至近位置）のうち第２差動カム筒２４４の繰り出し量に応じた位置まで移動する。これにより、２群レンズホルダー２４８が光軸方向に繰り出す。
【００９１】
ここで、図１３に示すように、第１カム溝２４３ｂのうち位置２４３ｂ１’から位置２４３ｂ５までの領域を第１実施形態における第１カム溝１４３ｂに比べてフィルム側に０．４ｍｍ移動させている。また、図１５に示すように、第２カム溝２４４ｂのうち位置２４４ｂ２から位置２４４ｂ５までの領域を第１実施形態における第２カム溝１４４ｂに比べて被写体側に０．４ｍｍ移動させている。さらに、図１５に示すように、第３カム溝２４４ｃのうち位置２４４ｃ２から位置２４４ｃ５までの領域を第１実施形態における第３カム溝１４４ｃに比べて被写体側に０．４ｍｍ移動させている。
【００９２】
これにより、ＷＩＤＥにおける第１レンズ群および第２レンズ群の光軸方向における位置関係は第１実施形態と変わらないが、第２差動カム筒２４４がフィルム側に０．４ｍｍ移動したことになる。この第２差動カム筒２４４の移動に伴って、第２差動カム筒２４４と一体に移動する第２直進ガイド筒２４７に係止されている第２フレアカット板２５０もフィルム側に０．４ｍｍ移動することとなるため、第２フレアカット板２５０が第２レンズ群と干渉することはなくなる。
【００９３】
このように、第１カム溝２４３ｂの形状を変更するとともに、この第１カム溝２４３ｂの形状の変更に対応して、レンズ群（第１レンズ群および第２レンズ群）の光軸上の位置関係を維持するように第２カム溝２４４ｂおよび第３カム溝２４４ｃの形状を変更すれば、レンズ群の光軸上の位置関係を変えることなく第２差動カム筒２４４と第２直進ガイド筒２４７の繰り出し量を適宜変えることができる。そして、第２差動カム筒２４４および第２直進ガイド筒２４７の繰り出し量を適宜変えることができれば、鏡筒内に余分なスペースを設けなくても、第２レンズ群が第２フレアカット板２５０に干渉するを防止することができる。なお、本実施形態においては、第２差動カム筒２４４を０．４ｍｍフィルム側に移動させているが、第２差動カム筒２４４をフィルム側に移動させる距離は適宜設定することができる。
【００９４】
一方、上述したように１群レンズ鏡筒２４５および２群レンズホルダー２４８がそれぞれ光軸方向に移動することにより、１群レンズ鏡筒２４５に保持されている第１レンズ群および２群レンズホルダー２４８に保持されている第２レンズ群がそれぞれ、光軸方向に移動して焦点調節が行われる。この後、撮影者がレリーズボタンを第２ストロークまで押し込むと、公知の露光動作が行われる。
【００９５】
次に、レンズ鏡筒が沈胴状態（図１０）からＴＥＬＥ待機状態（図１２）まで繰り出す際の動作を説明する。
【００９６】
撮影者がカメラ本体２５９に備え付けられたズームスイッチ（不図示）を操作して、ズーム位置をＴＥＬＥに設定すると、モーターの回転力が第１差動カム筒２４２に伝達される。これにより、第１差動カム筒２４２は、固定筒２４１とのヘリコイド係合により、光軸回りに回転しながら光軸方向に繰り出す。このとき、第２差動カム筒２４４の駆動ピン２５１は、第１カム溝２４３ｂに案内されて位置２４３ｂ１から位置２４３ｂ１８まで移動する。これにより、第２差動カム筒２４４は第１直進ガイド筒２４３に対して、光軸回りに回転しながら繰り出す。ここで、第２差動カム筒２４４の繰り出し量は、位置２４３ｂ１から位置２４３ｂ１８の間における駆動ピン２５１の光軸方向移動量に相当する。
【００９７】
第２差動カム筒２４４が繰り出されることにより、１群レンズ鏡筒２４５の１群カムピン２４５ａは、第２カム溝２４４ｂに案内されて位置２４４ｂ１から位置２４４ｂ１８まで移動する。これにより、１群レンズ鏡筒２４５は第２差動カム筒２４４に対して、位置２４４ｂ１から位置２４４ｂ１８の間における１群カムピン２４５ａの光軸方向移動量分だけ繰り出される。また、２群レンズホルダー２４８の２群カムピン２４８ａは、第３カム溝２４４ｃに案内されて位置２４４ｃ１から位置２４４ｃ１８まで移動する。これにより、２群レンズホルダー２４８は第２差動カム筒２４４に対して、位置２４４ｃ１から位置２４４ｃ１８の間における２群カムピン２４８ａの光軸方向移動量分だけ繰り出される。上述した動作により、レンズ鏡筒がＴＥＬＥ待機状態となる（図１２）。
【００９８】
ＴＥＬＥ待機状態において、撮影者がレリーズボタンを第２ストロークまで押し込むことにより、カメラ本体２５９内部に備えられた測距部（不図示）により被写体距離が測定され、この被写体距離情報に基づいて焦点調節が行われる。
【００９９】
焦点調節を行う場合、まず、モーターの回転力が第１差動カム筒２４２に伝達され、第１差動カム筒２４２が固定筒２４１とのヘリコイド係合により光軸回りに回転しながら光軸方向に繰り出す。このとき、第２差動カム筒２４４の駆動ピン２５１が、第１カム溝２４３ｂに案内されて位置２４３ｂ１９（∞位置）から位置２４３ｂ２０（至近位置）までの間のうちモーターの回転量（第１差動カム筒２４２の回転量）に応じた位置まで移動することにより、第２差動カム筒２４４を光軸方向に繰り出す。
【０１００】
この第２差動カム筒２４４の繰り出しにより、１群レンズ鏡筒２４５の１群カムピン２４５ａは第２カム溝２４４ｂに案内されて、位置２４４ｂ１９（∞位置）から位置２４４ｂ２０（至近位置）までの間のうち第２差動カム２４４の繰り出し量に応じた位置まで移動する。これにより、１群レンズ鏡筒２４５が光軸方向に繰り出す。また、２群レンズホルダー２４８の２群カムピン２４８ａは、第３カム溝２４４ｃに案内されて、位置２４４ｃ１９（∞位置）から位置２４４ｃ２０（至近位置）のうち第２差動カム筒２４４の繰り出し量に応じた位置まで移動する。これにより、２群レンズホルダー２４８が繰り込む。
【０１０１】
上述した動作により、１群レンズ鏡筒２４５に保持されている第１レンズ群および第２レンズホルダー２４８に保持されている第２レンズ群がそれぞれ、光軸方向に移動して焦点調節が行われる。この後、撮影者がレリーズボタンを第２ストロークまで押し込むと、公知の露光動作が行われる。
【０１０２】
一方、ズーム位置をＭ１、Ｍ２、Ｍ３に切り換えた場合にも、レンズ鏡筒は上述したような倍率切換および焦点調節の動作を行う。ここで、図１３に示すように、ズーム位置がＷＩＤＥからＭ１に切り換わる際、第１カム溝２４３ｂにおけるＷＩＤＥ〜Ｍ１までの領域のリフト量は、他のズーム位置切換領域（Ｍ１〜Ｍ２までの領域、Ｍ２〜Ｍ３までの領域、Ｍ３〜ＴＥＬＥまでの領域）におけるリフト量よりも小さくなっている。つまり、ＷＩＤＥ〜Ｍ１における第２差動カム筒２４４の駆動速度を他のズーム位置切換領域における第２差動カム筒２４４の駆動速度よりも小さくしている。ここで、図１５に示すように、第２差動カム筒２４４において、ＷＩＤＥ〜Ｍ１間のレンズ群（第１レンズ群および第２レンズ群）の駆動速度は、他のズーム位置間（Ｍ１〜Ｍ２、Ｍ２〜Ｍ３、Ｍ３〜ＴＥＬＥ）のレンズ群の駆動速度よりも大きくなっているため、ＷＩＤＥ〜Ｍ１間での第２差動カム筒２４４の駆動速度を小さくすることにより、レンズ鏡筒におけるＷＩＤＥ〜Ｍ１間での焦点距離変化速度を小さくしている。これにより、撮影者がファインダーを覗いてＷＩＤＥ〜Ｍ１間での倍率切換を行う場合、違和感を感じることなく倍率切換を行うことができる。
【０１０３】
また、ＴＥＬＥにおける焦点距離は、従来（図１６）のＴＥＬＥにおける焦点距離と同じになるように設定しており、ズーム位置がＭ１、Ｍ２、Ｍ３と切り換わるにつれて焦点距離が従来のズーム位置における焦点距離に近づいていく。
【０１０４】
【発明の効果】
本発明のレンズ鏡筒では、ワイド位置及びワイド位置と隣り合うミドル位置の間での焦点距離変化速度を遅くすることができ、ワイド位置からミドル位置の間での倍率切換の際にファインダーを覗く撮影者に違和感を感じさせることのないきめ細かい倍率切換を行うことができる。また、鏡筒内部での可動部品同士の干渉を防止することもできる。
【図面の簡単な説明】
【図１】本発明の第１実施形態であるレンズ鏡筒の分解斜視図。
【図２】第１実施形態であるレンズ鏡筒の断面図およびこのレンズ鏡筒を備えたカメラ内部のブロック図。
【図３】第１実施形態であるレンズ鏡筒の断面図（ＷＩＤＥ）。
【図４】第１実施形態であるレンズ鏡筒の断面図（ＴＥＬＥ）。
【図５】固定筒１４１の展開図。
【図６】第１直進ガイド筒１４３の展開図。
【図７】第２差動カム筒１４４の展開図。
【図８】第２差動カム筒１４４の部分展開図。
【図９】本発明の第２実施形態であるレンズ鏡筒の分解斜視図。
【図１０】第２実施形態であるレンズ鏡筒の断面図（沈胴）。
【図１１】第２実施形態であるレンズ鏡筒の断面図（ＷＩＤＥ）。
【図１２】第２実施形態であるレンズ鏡筒の断面図（ＴＥＬＥ）。
【図１３】第１直進ガイド筒２４３の展開図。
【図１４】第２差動カム筒２４４の展開図。
【図１５】第２差動カム筒２４４の部分展開図。
【図１６】従来技術における第１直進ガイド筒３４３の展開図。
【図１７】ズームリングの回転角と撮影レンズ群の光軸方向移動量との関係図。
【図１８】ズームリングの回転角と撮影レンズ群の光軸方向移動量との関係図。
【符号の説明】
１４１・２４１ 固定筒
１４２・２４２ 第１差動カム筒
１４３・２４３ 第１直進ガイド筒
１４４・２４４ 第２差動カム筒
１４５・２４５ １群レンズ鏡筒
１４６・２４６ ナットリング
１４７・２４７ 第２直進ガイド筒
１４８・２４８ ２群レンズホルダー
１４９・２４９ 第１フレアカット板
１５０・２５０ 第２フレアカット板
１５１・２５１ 駆動ピン
１５３・２５３ 板バネ
１５４・２５４ 固定リング
１５９・２５９ カメラ本体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lens barrel, and in particular, the lens group is moved in the optical axis direction by rotating the zoom ring to stop at a plurality of zoom positions, and focus adjustment (focus adjustment) is performed from infinity to the close range. The present invention relates to a lens barrel that can be used. The lens barrel of the present invention can be applied to optical devices such as 35 mm film cameras and digital video cameras.
[0002]
[Prior art]
The magnification switching device proposed in Japanese Patent Publication No. 6-100707 and the zoom position switching device proposed in Japanese Patent Laid-Open No. 9-80291 perform zooming and focusing by rotating one zoom ring.
[0003]
FIGS. 17 and 18 are schematic views of the main part of the magnification switching device proposed in Japanese Patent Publication No. 6-100707, that is, the relationship between the rotation angle of the zoom ring and the amount of movement of the lens group in the optical axis direction. Is. This magnification switching device is composed of two lens groups, and is a device that can perform zoom position selection and focus adjustment by rotating the zoom ring.
[0004]
Reference numeral 101 denotes a convex lens unit, 102 denotes a shutter blade also serving as an aperture, 103 denotes a concave lens unit, and 104 denotes an imaging surface. Here, an arrow C indicates the amount of movement of the convex lens unit 101 in the optical axis direction with respect to the rotation angle of the zoom ring. Further, arrows M1 to M4 and arrows N1 to N3 indicate the amount of movement of the concave lens unit 103 in the optical axis direction with respect to the rotation angle of the zoom ring.
[0005]
When the rotation angle of the zoom ring is 0 °, the convex lens unit 101, the shutter blades 102, and the concave lens unit 103 are in the positional relationship shown in the drawing on the upper side in FIG. That is, the magnification switching device is in a short focal length (hereinafter referred to as WIDE) state, and the lens focus is set to infinity (hereinafter referred to as ∞).
[0006]
Further, when the rotation angle of the zoom ring is 240 °, the convex lens unit 101, the shutter blade 102, and the concave lens unit 103 are in the positional relationship shown in the lower side of FIG. That is, the magnification switching device is in a long focal length (hereinafter referred to as TELE) state and the lens focus is in close proximity.
[0007]
If the zoom ring (not shown) is rotated by 30 ° around the optical axis from the state where the lens focus is at infinity (hereinafter referred to as ∞) at the WIDE zoom position, the convex lens unit 101 moves according to the arrow C. The concave lens unit 103 moves according to the arrow M1. In other words, when the rotation angle of the zoom ring is in the range of 0 ° to 30 °, the convex lens unit 101 and the concave lens unit 103 are fed out while maintaining a constant interval in the optical axis direction. As a result, the zooming operation of the lens group is not performed, and only the focus adjustment in the close direction of the lens group is performed in the WIDE state. Here, when the zoom ring is rotated by 30 °, the lens focus is in close proximity.
[0008]
Further, when the zoom ring is further rotated around the optical axis, the convex lens unit 101 moves in accordance with the arrow C, and the concave lens unit 103 moves in accordance with the arrow N. When the rotation angle of the zoom ring reaches 60 °, the lens group. The magnification of is switched to high magnification.
[0009]
When the device user wants to increase the magnification of the lens group a little more and switches to the normal (NOR) mode, the zoom ring rotates to a position at a rotation angle of 120 °. Here, when the zoom ring is at a rotation angle of 120 °, the lens focus is set to ∞. When the zoom ring is further rotated from the position of the rotation angle of 120 °, the focus adjustment in the closest direction of the lens group is performed within the range of the rotation angle of 120 ° to 150 °, and the zoom ring is positioned at the position of the rotation angle of 150 °. The lens will be in close proximity when
[0010]
Further, when the zoom ring is rotated to a position where the rotation angle is 180 °, the TELE state is established, and the lens focus at this time is set to ∞. When the zoom ring is further rotated from the position of the rotation angle of 180 °, the convex lens unit 101 moves according to the arrow C and the concave lens unit 103 moves according to the arrow M4, and the focus adjustment in the closest direction of the lens group is performed. Here, when the zoom ring is at a rotation angle of 240 °, the lens focus is in close proximity.
[0011]
With the configuration described above, the magnification switching device performs magnification switching and focus adjustment only by rotating a single zoom ring.
[0012]
The lens barrel proposed in Japanese Patent Application Laid-Open No. 10-282393 has a magnification switching mechanism proposed in Japanese Patent Publication No. 6-100707 and Japanese Patent Application Laid-Open No. 9-80291, and a camera during photographing. It has a structure in which three stages of cylinders are drawn from the main body. Here, the first-stage cylinder is extended by helicoid engagement with the fixed cylinder, and the second-stage cylinder is extended by a linear cam having a single extension amount as shown in FIG. It is fed out by a cam having a stepped shape described in Japanese Patent Publication No. 6-100707 and Japanese Patent Laid-Open No. 9-80291. In addition, this lens barrel is capable of flare cutting without providing extra space in the lens barrel by elastically deforming the flare cut plate even if a movable member arranged in the lens barrel interferes with the flare cut plate. The plate prevents the movement of the movable member in the lens barrel from being hindered.
[0013]
[Problems to be solved by the invention]
However, in the apparatus proposed in Japanese Patent Publication No. 6-100707 and Japanese Patent Laid-Open No. 9-80291 and the lens barrel proposed in Japanese Patent Laid-Open No. 10-282393, the focal point on the next tele side from wide is used. When the magnification is switched to the distance position, the change speed of the focal length is large, so that the photographer looking through the viewfinder feels uncomfortable and cannot perform fine magnification switching. Further, in the lens barrel proposed in Japanese Patent Laid-Open No. 10-282393, the movable member is intentionally interfered with the flare cut plate in order to ensure the movement of the movable member in the barrel.
[0014]
Therefore, the present invention provides a lens barrel that enables fine magnification switching without a sense of incongruity when a photographer looks through the viewfinder and switches magnification, and without providing extra space in the barrel. An object of the present invention is to provide a lens barrel that can prevent the movable member from interfering with the flare-cut plate.
[0015]
[Means for Solving the Problems]
  In order to achieve the above object, according to the present invention, in a lens barrel that changes the focal length stepwise at a plurality of zoom positions, a first cam member and a first cam member between a retracted position and a tele position. And a second cam member provided with a lens driving cam for driving the lens group in the optical axis direction. The lens driving cam is driven in the same manner as the second cam member. The lens group is driven in such a way that the driving speed of the lens group between the wide position and the middle position adjacent to the wide position is greater than the driving speed of the lens group between other adjacent zoom positions, The cam of the first cam member is a second cam in which the driving speed of the second cam member between the wide position and the middle position adjacent to the wide position is between other adjacent zoom positions. As it is smaller than the driving speed of the timber, driving the second cam memberThe focal length change speed between the wide position and the middle position adjacent to the wide position can be changed by driving the lens group by the lens driving cam and driving the second cam member by the cam of the first cam member. Approximately equal to the focal length change speed between adjacent zoom positionsIt is characterized by that.
[0016]
  This makes it wideNext to position and wide positionMiddleBetween positionsThe focal length change speed atBetween other adjacent zoom positionsThis is almost the same as the focal length change speed at, so that the photographer does not feel uncomfortable when zooming from wide to tele. Further, it is possible to prevent interference between movable parts inside the lens barrel.
[0021]
The lens barrel of the present invention can be used for an optical device such as a camera.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
FIG. 1 is an exploded perspective view of a lens barrel that is the first embodiment of the present invention. The lens barrel in the present embodiment is a three-stage retractable lens barrel provided with two so-called differential cam barrels. In this embodiment, the lens barrel is provided in the camera, but may be provided in other optical devices.
[0023]
Reference numeral 141 denotes a fixed cylinder fixed to the camera body, and a female helicoid is formed on the inner periphery of the fixed cylinder 141.
[0024]
Reference numeral 142 denotes a first differential cam cylinder, and a rectilinear groove extending in the optical axis direction is formed on the inner circumference of the first differential cam cylinder 142, and a male is formed at the outer peripheral rear end 142a of the first differential cam cylinder 142. A helicoid is formed. This male helicoid is engaged with a female helicoid formed on the fixed cylinder 141. The first differential cam cylinder 142 is interlocked with a motor (not shown) via a reduction gear train, and when the first differential cam cylinder 142 receives the rotational force of the motor, the helicoid engagement with the fixed cylinder 141 is caused. It moves in the optical axis direction while rotating around the optical axis.
[0025]
Reference numeral 143 denotes a first rectilinear guide tube (first cam member described in the claims of the present application), which can slide inside the first differential cam tube 142 with respect to the rotation of the first differential cam tube 142. Held in a state. A first cam groove 143 b is formed in the first rectilinear guide tube 143. Further, a convex portion is formed on the flange portion 143 a of the first rectilinear guide tube 143, and this convex portion engages with a groove portion formed in the inner periphery of the fixed tube 141 and extending in the optical axis direction. Here, when the first differential cam cylinder 142 rotates around the optical axis and moves in the optical axis direction, the first rectilinear guide cylinder 143 has a convex portion engaged with the groove portion of the fixed cylinder 141, so It moves only in the direction of the optical axis without rotating together with the one differential cam cylinder 142.
[0026]
Reference numeral 144 denotes a second differential cam cylinder (second cam member described in the claims of the present application) incorporated in the first linear guide cylinder 143, and a drive pin 151 is fitted on the outer periphery of the second differential cam cylinder. A recessed portion 144a is formed. The drive pin 151 fitted in the recess 144 a passes through the first cam groove 143 b formed in the first rectilinear guide cylinder 143 and engages with the rectilinear groove of the first differential cam cylinder 142.
[0027]
Reference numeral 145 denotes a first group lens barrel that holds the first lens group, and is incorporated in the inner diameter portion of the second rectilinear guide tube 147. Three first group cam pins 145a are formed in the circumferential direction of the first group lens barrel 145, and these first group cam pins 145a pass through grooves formed in the second rectilinear guide tube 147 extending in the optical axis direction. The second differential cam cylinder 144 is engaged with a second cam groove formed on the inner periphery.
[0028]
A nut ring 146 is attached between the claw portion 147a and the rear end flange portion 147b of the second rectilinear guide tube 147 so as to be rotatable around the optical axis. Two nut portions 146 a extending in the optical axis direction are formed on the outer periphery of the nut ring 146. Here, the drive pin 151 is fitted into the recess 144a of the second differential cam cylinder 144 in a state of passing through the nut portion 146a. Thus, the second differential cam cylinder 144 and the second rectilinear guide cylinder 147 are integrated in the optical axis direction with respect to the first rectilinear guide cylinder 143 (first differential cam cylinder 142) while relatively rotating. Move.
[0029]
Reference numeral 148 denotes a second group lens holder that holds the second lens group, and is incorporated in the second straight guide tube 147. Here, the second lens group is incorporated in the second group lens holder 148 with the leaf springs 153 arranged in the circumferential direction, and is pressed and fixed to the second group lens holder 148 side by the fixing ring 154. Three second group cam pins 148a are fitted in the circumferential direction of the second group lens holder 148, and these second group cam pins 148a pass through a groove formed in the second rectilinear guide tube 147 and extending in the optical axis direction. It engages with a third cam groove formed on the inner periphery of the differential cam cylinder 144.
[0030]
Reference numeral 149 denotes a first flare cut plate for cutting harmful light outside the photographing optical path. An opening 149 a for allowing the photographing light beam to pass is formed in the center of the first flare cut plate 149. In addition, an engaging portion 149 b that is convex in the optical axis direction is formed in the circumferential direction of the first flare cut plate 149, and the engaging portion 149 is a rear end flange of the first rectilinear guide tube 143. Locks to an engaged portion (not shown) formed in the portion 143a. As a result, the first flare cut plate 149 moves in the optical axis direction together with the first rectilinear guide tube 143.
[0031]
Reference numeral 150 denotes a second flare cut plate for cutting harmful light outside the photographing optical path. An opening 150 a for allowing the photographing light beam to pass is formed at the center of the second flare cut plate 150. A spring plate portion 150b is formed in the circumferential direction of the second flare cut plate 150, and an engaged portion 150c is formed at the tip of the spring plate portion 150b. Here, the claw portion 147c formed on the rear end flange portion 147b of the second rectilinear guide tube 147 is engaged with the engaged portion 150c, whereby the second flare cut plate 150 is moved to the second rectilinear guide tube 147. And move in the optical axis direction.
[0032]
FIG. 2 shows a cross-sectional view and a circuit diagram of a camera provided with the lens barrel of the present embodiment.
[0033]
Reference numeral 108 denotes a motor, and the rotational force of the motor 108 is transmitted to the long shaft gear 120 via a reduction gear train including the gear 121. The long shaft gear 120 meshes with a helicoid formed at the outer peripheral rear end 142 a of the first differential cam cylinder 142, and the rotational force of the long shaft gear 120 is transmitted to the first differential cam cylinder 142.
[0034]
Reference numeral 109 denotes a pulse plate composed of four propellers, and reference numeral 122 denotes a PI (photo interrupter) that detects the passage of the propeller of the pulse plate 109. Reference numeral 110 denotes a pulse detection circuit which detects a pulse from the PI 122 and sends it to the comparator 112a.
[0035]
Reference numeral 111 denotes a motor control circuit, which is configured to form a motor normal rotation energization circuit based on the output of the comparator 112a, and is configured to form a motor reverse rotation energization circuit based on the output of the comparator 112b. The motor 108 is rotated forward or backward by receiving a motor start signal from a logic control circuit 116 described later.
[0036]
Reference numeral 113 denotes a first differential cam cylinder rotation calculation circuit which receives output signals from a subject distance detection circuit 114 and a zooming signal processing circuit 115, which will be described later, and performs calculations shown in Table 1 below. Reference numeral 114 denotes a subject distance detection circuit, which converts subject distance information obtained by a distance measuring module 117 described later into a digital signal and outputs the digital signal to the first differential cam cylinder rotation calculation circuit 113. A zooming signal processing circuit 115 digitizes a position signal of a zooming operation member 118 (to be described later) as shown in Table 1 below and outputs it to the first differential cam cylinder rotation calculation circuit 113.
[0037]
Reference numeral 116 denotes a logic control circuit. When the photographer pushes a release button (not shown) to the first stroke, the motor forward rotation energization circuit of the motor control circuit 111 is made ready for operation or the release button is not pushed. As a result, the motor reversal energization circuit of the motor control circuit 111 is made ready for operation. In addition, the logic control circuit 116 issues a start signal to the distance measuring module 117 when the photographer pushes the release button to the first stroke, and allows sufficient time until the distance measuring operation by the distance measuring module 117 is completed. After that, a motor start signal is issued to the motor control circuit 111.
[0038]
Reference numeral 117 denotes a distance measurement module, which measures the subject distance by receiving an activation signal from the logic control circuit 116 and sends this subject distance information to the subject distance detection circuit 114.
[0039]
Reference numeral 118 denotes a zooming operation member operated to switch the zoom position of the photographing lens (the first lens group and the second lens group), and zooms at five points (WIDE, M (middle) 1, M2, M3, TELE). The position can be switched continuously. By operating the zooming operation member 118, the position signal at each zoom position is digitized by the zooming signal processing circuit 115 as shown in Table 1 below, and output to the first differential cam cylinder rotation calculation circuit 113. Reference numeral 119 denotes a finder lens moving mechanism that moves a finder lens (not shown) in the optical axis direction in response to an operation of the zooming operation member 118.
[0040]
With the above-described configuration, the camera magnification switching and focus adjustment operations in this embodiment will be described with reference to FIGS. 3 is a cross-sectional view of the lens barrel in the WIDE standby state, and FIG. 4 is a cross-sectional view of the lens barrel in the TELE standby state. 5 is a development view of the fixed cylinder 141, and FIG. 6 is a development view of the first rectilinear guide cylinder 143. FIG. 7 is a development view of the second differential cam cylinder 144, and FIG. 8 is a partial development view of the second differential cam cylinder 144.
[0041]
First, the retracted state of the lens barrel will be described. When the lens barrel is in the retracted state, the first differential cam cylinder 142 that is in helicoid engagement with the fixed cylinder 141 is not extended from the front surface of the fixed cylinder 141. The drive pin 151 of the second differential cam cylinder 144 is engaged with a first cam groove 143b formed on the inner periphery of the first rectilinear guide cylinder 143, and is at a position 143b1 of the first cam groove 143b.
[0042]
The first group cam pin 145a formed on the first group lens barrel 145 holding the first lens group is engaged with the second cam groove 144b formed on the second differential cam cylinder 144, and the second cam groove 144b at position 144b1. At this time, the first group lens barrel 145 is not extended relative to the second differential cam barrel 144. A second group cam pin 148a fitted into the second group lens holder 148 that holds the second lens group is engaged with a third cam groove 144c formed on the inner periphery of the second differential cam cylinder 144, and the third cam At the position 144c1 of the groove 144c.
[0043]
Next, the operation when the lens barrel is extended from the retracted state to the WIDE standby state (FIG. 3) will be described.
[0044]
When the photographer turns on the power of the camera main body 159 and sets the zoom position to WIDE by operating the zooming operation member 118, the motor 108 rotates (forward rotation), and the rotational force of the motor 108 is reduced by a reduction gear train ( (Including the gear 121) and the long shaft gear 120 and the first differential cam cylinder 142. Thereby, the first differential cam cylinder 142 is extended in the optical axis direction while rotating around the optical axis by the helicoid engagement with the fixed cylinder 141. At this time, the drive pin 151 attached to the second differential cam cylinder 144 moves from the position 143b1 to the position 143b2 while being guided by the first cam groove 143b. As a result, the second differential cam cylinder 144 is extended from the first rectilinear guide cylinder 143 (first differential cam cylinder 142) by an amount of movement in the optical axis direction of the drive pin 151 between the position 143b1 and the position 143b2. It is.
[0045]
As the second differential cam barrel 144 is extended, the first group cam pin 145a of the first group lens barrel 145 is guided by the second cam groove 144b and moves from the position 144b1 to the position 144b2. Accordingly, the first group lens barrel 145 is extended with respect to the second differential cam cylinder 144 by the amount of movement of the first group cam pin 145a between the position 144b1 and the position 144b2. The second group cam pin 148a attached to the second group lens holder 148 is guided by the third cam groove 144c and moves from the position 144c1 to the position 144c2. As a result, the second group lens holder 148 is retracted into the second differential cam cylinder 144 by the amount of movement in the optical axis direction of the second group cam pin 148a between the position 144c1 and the position 144c2. With the above-described operation, the lens barrel enters the WIDE standby state (FIG. 3).
[0046]
When the lens barrel is in the WIDE standby state (FIG. 3), the second lens group pushes the second flare cut plate 150 toward the film side. Here, since the claw portion 147c of the second rectilinear guide tube 147 is engaged with the engaged portion 150c of the second flare cut plate 150, the second flare cut plate 150 is elastically deformed by the spring plate portion 150b. The opening 150a is inflated to the film side (image surface side).
[0047]
When the photographer pushes the release button to the first stroke in the WIDE standby state, the distance measuring module 117 that receives the output signal from the logic control circuit 116 performs the distance measuring operation. The subject distance information is sent to the subject distance detection circuit 114, converted into a digital signal by the subject distance detection circuit 114, and then output to the first differential cam cylinder rotation calculation circuit 113. A position signal when the zoom position is set to WIDE by operating the zooming operation member 118 is digitized by the zooming signal processing circuit 115 and then output to the first differential cam cylinder rotation calculation circuit 113. As a result, the first differential cam cylinder rotation calculation circuit 116 performs the calculations shown in Table 1 below according to the output signals of the subject distance detection circuit 114 and the zooming signal processing circuit 115. Specifically, when the photographer operates the zooming operation member 118 to set the zoom position to WIDE (focal length f = 35 mm), the distance measurement module 117 measures the subject distance to 4 m. In this case, the first differential cam barrel rotation calculation circuit 113 receives the output signals of the subject distance detection circuit 114 and the zooming signal processing circuit 115 and performs the calculation shown in Table 1 below. Stored as a reference value for the comparator 12a.
[0048]
[Table 1]

[0049]
On the other hand, the motor control circuit 111 receives the start signal from the logic control circuit 116 and rotates the motor 108 in the normal direction to rotate the first differential cam cylinder 142 around the optical axis. Accordingly, the first lens group and the second lens group move in the optical axis direction as will be described later.
[0050]
The rotation of the first differential cam cylinder 142 is pulsed by the pulse plate 109 and output to the pulse detection circuit 110, and the pulse is detected by the pulse detection circuit 110 and sent to the comparator 112a.
[0051]
While the first differential cam cylinder 142 continues to rotate due to normal rotation of the motor 108, the pulse detection circuit 110 detects pulses, and the number of pulses is 11 pulses (first differential cam cylinder rotation calculation). (The reference value of the comparator 112a calculated in the circuit 113), the comparator 112a inverts and outputs a signal for ending the normal rotation of the motor 108 to the motor control circuit 111. The motor control circuit 111 Is short-circuited to apply an electric brake to the motor 108 to stop the normal rotation of the motor 108.
[0052]
By the circuit operation described above, the first differential cam cylinder 142 is extended in the optical axis direction while rotating around the optical axis by the helicoid engagement with the fixed cylinder 141. At this time, the drive pin 151 of the second differential cam cylinder 144 is guided by the first cam groove 143b and rotates between the position 143b3 (∞ position) and the position 143b4 (closest position) of the motor 108 (first position). 1) and the second differential cam cylinder 144 is fed out in the optical axis direction.
[0053]
By the extension of the second differential cam barrel 144, the first group cam pin 145a of the first group lens barrel 145 is guided by the second cam groove 144b, and from the position 144b3 (∞ position) to the position 144b4 (closest position). The second differential cam 144 moves to a position corresponding to the amount of extension. Thereby, the first group lens barrel 145 is extended in the optical axis direction. Further, the second group cam pin 148a of the second group lens holder 148 is guided by the third cam groove 144c, and the amount of extension of the second differential cam cylinder 144 from the position 144c3 (∞ position) to the position 144c4 (closest position) is set. Move to the corresponding position. Thereby, the second group lens holder 148 is extended in the optical axis direction.
[0054]
Through the above-described operation, the first lens group held by the first group lens barrel 145 and the second lens group held by the second group lens holder 148 are moved in the optical axis direction to perform focus adjustment. .
[0055]
Thereafter, when the photographer pushes the release button to the second stroke, a known exposure operation is performed. When the release button is released and the release button returns to the original position, the motor control circuit 111 receives the start signal from the logic control circuit 116 and rotates (reverses) the motor 108. As a result, the first differential cam barrel 142 rotates around the optical axis, the lens barrel returns to the WIDE standby state, and the switch SW is turned off after the lens barrel enters the WIDE standby state. 112b reverses and the rotation of the motor 108 stops. Then, when the film is wound up by one frame, the camera returns to the state before photographing.
[0056]
In this embodiment, the zoom position is switched with five zoom positions WIDE, M1, M2, M3, and TELE, but the zoom ratio is switched by increasing or decreasing the number of zoom positions to five or more. May be performed.
[0057]
In this embodiment, the pulse plate 109 and the pulse detection circuit 110 are provided to detect the rotation angle of the first differential cam cylinder 142 (the positional relationship between the first lens group and the second lens group in the optical axis direction). Thus, the rotation stop timing of the motor 108 is determined. However, the present invention is not limited to this, and a pulse motor is used for the motor 108 and the number of output pulses from the first differential cam cylinder rotation calculation circuit 113 is determined. Then, the pulse motor may be rotated to rotate the first differential cam cylinder 142 to a position of a predetermined rotation angle, and the rotation stop timing of the motor 108 may be determined. In this way, since the signal from the first differential cam cylinder rotation calculation circuit 113 may be directly input to the motor control circuit 111, the pulse plate 109, the pulse detection circuit 110, and the comparator 112a are provided in the camera body 159. This eliminates the need for a smaller camera.
[0058]
Next, the operation when the lens barrel is extended from the retracted state to the TELE state (FIG. 4) will be described.
[0059]
When the photographer operates the zooming operation member 118 and sets the zoom position to TELE, the motor 108 rotates (forward rotation), and the rotational force of the motor 108 reduces the reduction gear train (including the gear 121) and the long axis. It is transmitted to the first differential cam cylinder 142 via the gear 120. Thereby, the first differential cam cylinder 142 is extended in the optical axis direction while rotating around the optical axis by the helicoid engagement with the fixed cylinder 141. At this time, the drive pin 151 of the second differential cam cylinder 144 moves from the position 143b1 to the position 143b18 while being guided by the first cam groove 143b. Thus, the second differential cam cylinder 144 is extended while rotating around the optical axis with respect to the first rectilinear guide cylinder 143 (first differential cam cylinder 142). Here, the amount of extension of the second differential cam cylinder 144 corresponds to the amount of movement of the drive pin 151 between the position 143b1 and the position 43b18 in the optical axis direction.
[0060]
As the second differential cam barrel 144 is extended, the first group cam pin 145a of the first group lens barrel 145 is guided by the second cam groove 144b and moved from the position 144b1 to the position 144b18. Accordingly, the first group lens barrel 145 is extended with respect to the second differential cam cylinder 144 by the amount of movement of the first group cam pin 145a in the optical axis direction between the position 144b1 and the position 144b18. The second group cam pin 148a of the second group lens holder 148 is guided by the third cam groove 144c and moves from the position 144c1 to the position 144c18. As a result, the second group lens holder 148 is extended with respect to the second differential cam cylinder 144 by the amount of movement of the second group cam pin 148a between the position 144c1 and the position 144c18 in the optical axis direction. With the above-described operation, the lens barrel enters the TELE standby state (FIG. 4).
[0061]
When the photographer pushes the release button to the first stroke in the TELE standby state, the distance measuring module 117 receives the output signal from the logic control circuit 116 and the distance measuring operation is performed, and the subject measured by the distance measuring module 117 is measured. Focus adjustment is performed based on the distance. When performing the focus adjustment, first, the rotational force of the motor 108 is transmitted to the first differential cam cylinder 142, and the first differential cam cylinder 142 rotates around the optical axis by the helicoid engagement with the fixed cylinder 141 while rotating the optical axis. Pull out in the direction. At this time, the drive pin 151 of the second differential cam cylinder 144 is guided by the first cam groove 143b and rotates between the position 143b19 (∞ position) and the position 143b20 (closest position) of the motor 108 (first The second differential cam cylinder 144 is moved out in the optical axis direction by moving to a position corresponding to the rotation amount of the differential cam cylinder 142).
[0062]
By the extension of the second differential cam barrel 144, the first group cam pin 145a of the first group lens barrel 145 is guided by the second cam groove 144, and the second differential cam 144 is between the positions 144b19 and 144b20. Move to a position corresponding to the amount of feed. Thereby, the first group lens barrel 145 is extended in the optical axis direction. Further, the second group cam pin 148a of the second group lens holder 148 is guided by the third cam groove 144c, and the second differential cam cylinder 144 is located between the position 144c19 (∞ position) and the position 144c20 (closest position). Move to the position corresponding to the feed amount. Thereby, the second group lens holder 148 is retracted.
[0063]
Through the above-described operation, the first lens group held by the first group lens barrel 145 and the second lens group held by the second group lens holder 148 are moved in the optical axis direction to perform focus adjustment. . When the photographer pushes the release button up to the second stroke, a known exposure operation is performed. After the exposure is completed, the motor 108 is driven to rotate the first differential cam cylinder 142 around the optical axis to retract the lens barrel to the TELE standby position and to wind the film. As a result, the single frame shooting of the film is completed and the camera returns to the state before the start of shooting.
[0064]
On the other hand, even when the zoom position is switched to M1, M2, or M3, the lens barrel performs the magnification switching and focus adjustment operations as described above.
[0065]
Here, as shown in FIG. 6, when the zoom position is switched from WIDE to M1, the lift amount of the area from WIDE to M1 in the first cam groove 143b is different from the other zoom position switching areas (M1 to M2). The lift amount in the region, the region from M2 to M3, and the region from M3 to TELE) is smaller. That is, the driving speed of the second differential cam cylinder 144 in WIDE to M1 is set to be lower than the driving speed of the second differential cam cylinder 144 in other zoom position switching regions. Here, as shown in FIG. 8, in the second differential cam cylinder 144, the driving speed of the lens group (the first lens group and the second lens group) between WIDE and M1 is between other zoom positions (M1 to M1). M2, M2 to M3, and M3 to TELE) are higher than the driving speed of the lens group. Therefore, by reducing the driving speed of the second differential cam cylinder 144 between WIDE and M1, The focal length change speed between WIDE and M1 is reduced. Thereby, when a photographer looks into a finder and performs magnification switching between WIDE-M1, magnification switching can be performed without feeling uncomfortable.
[0066]
The lens barrel of the present embodiment cannot be continuously zoomed, and can only zoom in increments of 5 to 6 focal lengths. Further, because of the sensor that knows the focal length, the rotation angles of the cam cylinders between adjacent focal lengths are equal. Here, when a general optical design is performed and the first lens group is linearly extended, the focal length at WIDE and the focal length at the next zoom position are greatly separated as in the prior art.
[0067]
For this reason, the angle of view changes greatly only by zooming from WIDE to TELE, and the photographer looking through the viewfinder feels uncomfortable. Moreover, it cannot be stopped between WIDE and a predetermined middle stage.
[0068]
Therefore, by making the focal length at the zoom position (M1) adjacent to WIDE close to the focal length in WIDE as in the present embodiment, zooming close to equal intervals can be realized visually and sensibly. It is possible to prevent the user from feeling uncomfortable.
[0069]
Further, the focal lengths in WIDE and TELE are set to be the same as those in the conventional (FIG. 16) WIDE and TELE, and the focal lengths change as the zoom position is switched to M1, M2, and M3. It approaches the focal length at the zoom position.
[0070]
(Second Embodiment)
Next, a lens barrel that is a second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the lens barrel is provided in the camera, but may be provided in another optical device.
[0071]
FIG. 9 is an exploded perspective view of the lens barrel in the present embodiment. Similarly to the lens barrel of the first embodiment, the lens barrel in the present embodiment is also a three-stage retractable lens barrel having two so-called differential cam barrels.
[0072]
Reference numeral 241 denotes a fixed cylinder fixed to the camera body. A female helicoid is formed on the inner periphery of the fixed cylinder 241.
[0073]
Reference numeral 242 denotes a first differential cam cylinder (first cam member described in the claims of the present application), and a rectilinear groove extending in the optical axis direction is formed on the inner periphery of the first differential cam cylinder 242, and A male helicoid is formed on the outer peripheral rear end 242 a of the differential cam cylinder 242. This male helicoid is engaged with a female helicoid formed in the fixed cylinder 241. The first differential cam cylinder 242 is interlocked with a motor (not shown) via a reduction gear train. When the first differential cam cylinder 242 receives the rotational force of the motor, the first differential cam cylinder 242 is engaged with a helicoid with the fixed cylinder 241. It moves in the optical axis direction while rotating around the optical axis.
[0074]
Reference numeral 243 denotes a first rectilinear guide cylinder, which is held inside the first differential cam cylinder 242 so as to be slidable with respect to the rotation of the first differential cam cylinder 242. A first cam groove is formed in the first rectilinear guide tube 243. Further, a convex portion is formed at the outer peripheral rear end portion of the first rectilinear guide tube 243, and this convex portion is engaged with a groove portion formed in the inner periphery of the fixed tube 241 and extending in the optical axis direction. Here, when the first differential cam cylinder 242 rotates around the optical axis and moves in the optical axis direction, the first rectilinear guide cylinder 243 has the convex portion engaged with the groove portion of the fixed cylinder 241. It moves only in the optical axis direction without rotating integrally with the one differential cam cylinder 242.
[0075]
Reference numeral 244 denotes a second differential cam cylinder (second cam member described in the claims of the present application) incorporated in the first linear guide cylinder 243, and a drive pin 251 is fitted on the outer periphery of the second differential cam cylinder. A recessed portion 244a is formed. The drive pin 251 fitted in the recess 244a passes through the first cam groove formed in the first rectilinear guide tube 243 and engages with the rectilinear groove of the first differential cam tube 242.
[0076]
Reference numeral 245 denotes a first lens barrel that holds the first lens group, and is incorporated in the second rectilinear guide tube 247. Three first group cam pins 245a are formed in the circumferential direction of the first group lens barrel 245, and these first group cam pins 245a pass through a groove formed in the second rectilinear guide tube 247 extending in the optical axis direction. , Engages with a second cam groove formed on the inner periphery of the second differential cam cylinder 244.
[0077]
A nut ring 246 is attached between the claw portion 247a and the rear end flange portion 247b of the second rectilinear guide tube 247 so as to be rotatable around the optical axis. Two nut portions 246 a extending in the optical axis direction are formed on the outer periphery of the nut ring 246. Here, the drive pin 251 is fitted into the recess 244a of the second differential cam cylinder 244 in a state of passing through the nut portion 246a. Accordingly, the second differential cam cylinder 244 and the second rectilinear guide cylinder 247 move in the optical axis direction with respect to the first rectilinear guide cylinder 243 (first differential cam cylinder 242) while rotating relatively.
[0078]
Reference numeral 248 denotes a second group lens holder that holds the second lens group, and is incorporated in the second linear guide tube 247. Here, the second lens group is incorporated in the second group lens holder 248 with the leaf springs 253 arranged in the circumferential direction, and is pressed and fixed to the second group lens holder 248 side by the fixing ring 254. Three second group cam pins 248a are fitted in the circumferential direction of the second group lens holder 248, and these second group cam pins 248a pass through a groove portion formed in the second rectilinear guide tube 247 extending in the optical axis direction to form the second group cam pin 248a. It engages with a third cam groove formed on the inner periphery of the differential cam cylinder 244.
[0079]
Reference numeral 249 denotes a first flare cut plate for cutting harmful light outside the photographing optical path. An opening 249 a for allowing the photographing light beam to pass is formed in the center of the first flare cut plate 249. In addition, an engagement portion 249 b that is convex in the optical axis direction is formed in the circumferential direction of the first flare cut plate 249, and this engagement portion 249 is a rear end flange of the first rectilinear guide tube 243. Locks to an engaged portion (not shown) formed in the portion 243a. As a result, the first flare cut plate 249 moves integrally with the first rectilinear guide tube 243 in the optical axis direction.
[0080]
Reference numeral 250 denotes a second flare cut plate for cutting harmful light outside the photographing optical path. An opening 250 a for allowing the photographing light beam to pass is formed at the center of the second flare cut plate 250. Further, an engaged portion 250b is formed in the circumferential direction of the second flare cut plate 250, and a claw portion formed in the rear end flange portion 247b of the second rectilinear guide tube 247 is formed in the engaged portion 250b. 247c is locked. Accordingly, the second flare cut plate 250 moves in the optical axis direction integrally with the second rectilinear guide tube 247.
[0081]
With the above-described configuration, operations of magnification switching and focus adjustment of a camera provided with the lens barrel of this embodiment will be described with reference to FIGS. 10 is a sectional view of the lens barrel in the retracted state, FIG. 11 is a sectional view of the lens barrel in the WIDE standby state, and FIG. 12 is a sectional view of the lens barrel in the TELE standby state. 13 is a development view of the first rectilinear guide cylinder 243, FIG. 14 is a development view of the second differential cam cylinder 244, and FIG. 15 is a partial development view of the second differential cam cylinder 244.
[0082]
First, the retracted state of the lens barrel will be described. When the lens barrel is in the retracted state (FIG. 10), the first differential cam cylinder 242 that is helicoidally engaged with the fixed cylinder 241 is not extended from the front surface of the fixed cylinder 241. The drive pin 251 of the second differential cam cylinder 244 is engaged with the first cam groove 243b formed in the first rectilinear guide cylinder 243, and is at the position 243b1 of the first cam groove 243b.
[0083]
The first group cam pin 245a formed on the first group lens barrel 245 holding the first lens group is engaged with the second cam groove 244b formed on the second differential cam cylinder 244, and the second cam groove It is at position 244b1 of 244b. At this time, the first group lens barrel 245 is not extended relative to the second differential cam barrel 244.
[0084]
The second group cam pin 248a of the second group lens holder 248 that holds the second lens group is engaged with a third cam groove 244c formed on the inner periphery of the second differential cam cylinder 244, and the third cam groove 244c. At position 244c1.
[0085]
Next, the operation when the lens barrel is extended from the retracted state (FIG. 10) to the WIDE standby state (FIG. 11) will be described.
[0086]
When the photographer turns on the power of the camera body 259 and operates a zoom switch (not shown) provided on the camera body 259 to set the zoom position to WIDE, the motor rotates and the rotational force of the motor is reduced. It is transmitted to the first differential cam cylinder 242. Thereby, the first differential cam cylinder 242 is extended in the optical axis direction while rotating around the optical axis by the helicoid engagement with the fixed cylinder 241. At this time, the drive pin 251 attached to the second differential cam cylinder 244 moves from the position 243b1 to the position 243b2 while being guided by the first cam groove 243b. As a result, the second differential cam cylinder 244 is extended relative to the first rectilinear guide cylinder 243 by the amount of movement of the drive pin 251 in the optical axis direction between the position 243b1 and the position 243b2.
[0087]
As the second differential cam barrel 244 is extended, the first group cam pin 245a of the first group lens barrel 245 is guided by the second cam groove 244b and moves from the position 244b1 to the position 244b2. Thus, the first group lens barrel 245 is extended with respect to the second differential cam cylinder 244 by the amount of movement of the first group cam pin 245a in the optical axis direction between the position 244b1 and the position 244b2. The second group cam pin 248a attached to the second group lens holder 248 is guided by the third cam groove 244c and moves from the position 244c1 to the position 244c2. As a result, the second group lens holder 248 is retracted with respect to the second differential cam cylinder 244 by the amount of movement of the second group cam pin 248a between the position 244c1 and the position 244c2. With the above-described operation, the lens barrel enters the WIDE standby state (FIG. 11).
[0088]
In the WIDE standby state, when the photographer pushes the release button to the first stroke, the subject distance is measured by a distance measuring unit (not shown) provided in the camera body 259, and focus adjustment is performed based on the subject distance information. Is done.
[0089]
When performing focus adjustment, first, the rotational force of the motor is transmitted to the first differential cam cylinder 242, and the first differential cam cylinder 242 rotates around the optical axis by the helicoid engagement with the fixed cylinder 241, while rotating the optical axis. Pull out in the direction. At this time, the drive pin 251 of the second differential cam cylinder 244 is guided by the first cam groove 243b and the amount of rotation of the motor (first position) from the position 243b3 (∞ position) to the position 243b4 (closest position). The second differential cam cylinder 244 is extended in the optical axis direction by moving to a position corresponding to the rotation amount of the differential cam cylinder 242).
[0090]
By the extension of the second differential cam barrel 244, the first group cam pin 245a of the first group lens barrel 245 is guided by the second cam groove 244b, and from the position 244b3 (∞ position) to the position 244b4 (closest position). Among them, the second differential cam 244 moves to a position corresponding to the feed amount. Thereby, the first group lens barrel 245 is extended in the optical axis direction. Further, the second group cam pin 248a of the second group lens holder 248 is guided by the third cam groove 244c so that the second differential cam cylinder 244 is extended from the position 244c3 (∞ position) to the position 244c4 (closest position). Move to the corresponding position. Thereby, the second group lens holder 248 is extended in the optical axis direction.
[0091]
Here, as shown in FIG. 13, the region from the position 243b1 ′ to the position 243b5 in the first cam groove 243b is moved 0.4 mm to the film side as compared with the first cam groove 143b in the first embodiment. . As shown in FIG. 15, the region from the position 244b2 to the position 244b5 in the second cam groove 244b is moved by 0.4 mm toward the subject as compared with the second cam groove 144b in the first embodiment. Further, as shown in FIG. 15, the region from the position 244c2 to the position 244c5 in the third cam groove 244c is moved by 0.4 mm toward the subject as compared with the third cam groove 144c in the first embodiment.
[0092]
Thus, the positional relationship in the optical axis direction between the first lens group and the second lens group in WIDE is the same as in the first embodiment, but the second differential cam cylinder 244 has moved 0.4 mm toward the film side. . Along with the movement of the second differential cam cylinder 244, the second flare cut plate 250 locked to the second rectilinear guide cylinder 247 that moves integrally with the second differential cam cylinder 244 is also moved to the film side. Since it moves by 4 mm, the second flare cut plate 250 does not interfere with the second lens group.
[0093]
As described above, the shape of the first cam groove 243b is changed, and the position of the lens group (the first lens group and the second lens group) on the optical axis corresponding to the change of the shape of the first cam groove 243b. If the shapes of the second cam groove 244b and the third cam groove 244c are changed so as to maintain the relationship, the second differential cam cylinder 244 and the second rectilinear guide cylinder are not changed without changing the positional relationship of the lens group on the optical axis. The feeding amount of 247 can be changed as appropriate. If the amount of extension of the second differential cam cylinder 244 and the second rectilinear guide cylinder 247 can be appropriately changed, the second lens group can be moved to the second flare cut plate 250 without providing an extra space in the lens barrel. It is possible to prevent interference. In the present embodiment, the second differential cam cylinder 244 is moved to the 0.4 mm film side, but the distance for moving the second differential cam cylinder 244 to the film side can be set as appropriate.
[0094]
On the other hand, as described above, the first group lens barrel 245 and the second group lens holder 248 move in the optical axis direction, so that the first lens group and the second group lens holder 248 held by the first group lens barrel 245 are provided. Each of the second lens groups held in the lens moves in the direction of the optical axis to perform focus adjustment. Thereafter, when the photographer pushes the release button to the second stroke, a known exposure operation is performed.
[0095]
Next, the operation when the lens barrel is extended from the retracted state (FIG. 10) to the TELE standby state (FIG. 12) will be described.
[0096]
When the photographer operates a zoom switch (not shown) provided in the camera body 259 to set the zoom position to TELE, the rotational force of the motor is transmitted to the first differential cam cylinder 242. Thereby, the first differential cam cylinder 242 is extended in the optical axis direction while rotating around the optical axis by the helicoid engagement with the fixed cylinder 241. At this time, the drive pin 251 of the second differential cam cylinder 244 is guided by the first cam groove 243b and moves from the position 243b1 to the position 243b18. As a result, the second differential cam cylinder 244 extends with respect to the first rectilinear guide cylinder 243 while rotating around the optical axis. Here, the amount of extension of the second differential cam cylinder 244 corresponds to the amount of movement of the drive pin 251 in the optical axis direction between the position 243b1 and the position 243b18.
[0097]
When the second differential cam barrel 244 is extended, the first group cam pin 245a of the first group lens barrel 245 is guided by the second cam groove 244b and moves from the position 244b1 to the position 244b18. Thus, the first group lens barrel 245 is extended with respect to the second differential cam cylinder 244 by the amount of movement of the first group cam pin 245a between the position 244b1 and the position 244b18 in the optical axis direction. Further, the second group cam pin 248a of the second group lens holder 248 moves from the position 244c1 to the position 244c18 while being guided by the third cam groove 244c. Accordingly, the second group lens holder 248 is extended with respect to the second differential cam cylinder 244 by the amount of movement of the second group cam pin 248a between the position 244c1 and the position 244c18 in the optical axis direction. With the above-described operation, the lens barrel enters the TELE standby state (FIG. 12).
[0098]
In the TELE standby state, when the photographer pushes the release button to the second stroke, the subject distance is measured by a distance measuring unit (not shown) provided in the camera body 259, and focus adjustment is performed based on the subject distance information. Is done.
[0099]
When performing focus adjustment, first, the rotational force of the motor is transmitted to the first differential cam cylinder 242, and the first differential cam cylinder 242 rotates around the optical axis by the helicoid engagement with the fixed cylinder 241, while rotating the optical axis. Pull out in the direction. At this time, the drive pin 251 of the second differential cam cylinder 244 is guided by the first cam groove 243b and rotates between the position 243b19 (∞ position) and the position 243b20 (closest position). The second differential cam cylinder 244 is extended in the optical axis direction by moving to a position corresponding to the rotation amount of the differential cam cylinder 242).
[0100]
By the extension of the second differential cam barrel 244, the first group cam pin 245a of the first group lens barrel 245 is guided by the second cam groove 244b and between the position 244b19 (∞ position) and the position 244b20 (closest position). Among them, the second differential cam 244 moves to a position corresponding to the feed amount. Thereby, the first group lens barrel 245 is extended in the optical axis direction. Further, the second group cam pin 248a of the second group lens holder 248 is guided by the third cam groove 244c so that the second differential cam cylinder 244 is extended from the position 244c19 (∞ position) to the position 244c20 (closest position). Move to the corresponding position. Thereby, the second group lens holder 248 is retracted.
[0101]
By the above-described operation, the first lens group held by the first group lens barrel 245 and the second lens group held by the second lens holder 248 are moved in the optical axis direction to perform focus adjustment. . Thereafter, when the photographer pushes the release button to the second stroke, a known exposure operation is performed.
[0102]
On the other hand, even when the zoom position is switched to M1, M2, or M3, the lens barrel performs the magnification switching and focus adjustment operations as described above. Here, as shown in FIG. 13, when the zoom position is switched from WIDE to M1, the lift amount of the area from WIDE to M1 in the first cam groove 243b is different from the other zoom position switching areas (M1 to M2). The lift amount in the region, the region from M2 to M3, and the region from M3 to TELE) is smaller. That is, the driving speed of the second differential cam cylinder 244 in WIDE to M1 is set to be lower than the driving speed of the second differential cam cylinder 244 in other zoom position switching regions. Here, as shown in FIG. 15, in the second differential cam cylinder 244, the driving speed of the lens group (the first lens group and the second lens group) between WIDE and M1 is between other zoom positions (M1 to M1). M2, M2 to M3, and M3 to TELE) are higher than the driving speed of the lens group. Therefore, by reducing the driving speed of the second differential cam cylinder 244 between WIDE to M1, The focal length change speed between WIDE and M1 is reduced. Thereby, when the photographer looks into the finder and switches the magnification between WIDE and M1, the magnification can be switched without feeling uncomfortable.
[0103]
Further, the focal length in TELE is set to be the same as the focal length in TELE in the prior art (FIG. 16), and the focal length becomes the focal point in the conventional zoom position as the zoom position is switched to M1, M2, and M3. Approaching the distance.
[0104]
【The invention's effect】
  The lens barrel of the present inventionsoIs, WaIdNext to position and wide positionMiddlePositionCan change the focal length change speed betweenpositionOrRamiDollarPositionIt is possible to perform detailed magnification switching without causing the photographer looking through the viewfinder to feel uncomfortable when switching magnification between the two.In addition, it is possible to prevent interference between movable parts inside the lens barrel.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a lens barrel according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of the lens barrel according to the first embodiment and a block diagram of the inside of the camera equipped with the lens barrel.
FIG. 3 is a cross-sectional view (WIDE) of a lens barrel according to the first embodiment.
FIG. 4 is a cross-sectional view (TELE) of a lens barrel according to the first embodiment.
FIG. 5 is a development view of the fixed cylinder 141. FIG.
FIG. 6 is a development view of the first rectilinear guide tube 143;
7 is a development view of the second differential cam cylinder 144. FIG.
8 is a partial development view of the second differential cam cylinder 144. FIG.
FIG. 9 is an exploded perspective view of a lens barrel that is a second embodiment of the present invention.
FIG. 10 is a cross-sectional view (collapsed) of a lens barrel according to a second embodiment.
FIG. 11 is a cross-sectional view (WIDE) of a lens barrel according to a second embodiment.
FIG. 12 is a cross-sectional view (TELE) of a lens barrel according to a second embodiment.
13 is a development view of the first straight guide tube 243. FIG.
14 is a development view of the second differential cam cylinder 244. FIG.
15 is a partial development view of the second differential cam cylinder 244. FIG.
FIG. 16 is a development view of a first straight guide tube 343 in the prior art.
FIG. 17 is a diagram showing the relationship between the rotation angle of the zoom ring and the amount of movement of the photographic lens group in the optical axis direction.
FIG. 18 is a diagram showing the relationship between the rotation angle of the zoom ring and the amount of movement of the taking lens group in the optical axis direction.
[Explanation of symbols]
141 ・ 241 fixed cylinder
142/242 1st differential cam cylinder
143/243 first straight guide tube
144/244 Second differential cam cylinder
145 ・ 245 1 group lens barrel
146 ・ 246 Nut Ring
147/247 Second straight guide tube
148/248 2-group lens holder
149/249 First flare cut plate
150 ・ 250 Second flare cut plate
151 ・ 251 Drive pin
153 ・ 253 leaf spring
154/254 fixing ring
159/259 Camera body

Claims (5)

In a lens barrel that changes the focal length step by step at multiple zoom positions,
A first cam member;
The first cam member is cam-driven in the optical axis direction between the retracted position and the telephoto position, and has a second cam member having a lens driving cam for driving the lens group in the optical axis direction. And
The lens driving cam has a driving speed of the lens group between a wide position and a middle position adjacent to the wide position at the same driving amount of the second cam member. Driving the lens group so as to be faster than the driving speed of the lens group,
The cam of the first cam member is the second cam member in which the driving speed of the second cam member between the wide position and the middle position adjacent to the wide position is between other adjacent zoom positions. so as to be smaller than the drive speed of the drives the second cam member,
The focal length change between the wide position and the middle position adjacent to the wide position by driving the lens group by the lens driving cam and driving the second cam member by the cam of the first cam member. A lens barrel characterized in that a speed is made substantially equal to a focal length change speed between other adjacent zoom positions . The first cam member moves in the optical axis direction, and the second cam member moves in the optical axis direction while rotating around the optical axis,
The driving amount in the optical axis direction of the second cam member between the wide position and the middle position adjacent to the wide position is set in the optical axis direction of the second cam member between other adjacent zoom positions. The lens barrel according to claim 1, wherein the lens barrel is smaller than a driving amount. Switching means for switching the zoom position by user operation, and focus adjustment signal output means for outputting a signal for performing focus adjustment,
By operating the switching means, the lens group is moved in the optical axis direction to set a predetermined zoom position, and the lens group is moved in the optical axis direction by the output of the focus adjustment signal output means to adjust the focus. The lens barrel according to claim 1, wherein the lens barrel is performed.   A camera having the lens barrel according to any one of claims 1 to 3.   An optical apparatus having the lens barrel according to any one of claims 1 to 3.

Images