JP4026756B2 - camera - Google Patents

Description

【００３３】
表１はマトリクス表になっており、カムピンが外れずにポテンショメータが働いてカムピンの停止位置によりレンズの絶対位置が検出される場合１通り、および二つのカムピンのいずれの導体部側外れた場合４通り、あるいはカムピン双方がいずれかの導体側に外れた場合４通り、合わせて９通りの状態がそれぞれ示されている。表１の各欄は行番号と列番号によって区別されており、行番号（１〜３）のうちいずれかと列番号（１〜３）のうちいずれかが指定されると９つあるうちのいずれかの欄が指定される。たとえば行番号と列番号とを１×１で表わせばマトリクス表の左上の欄が示され、２×２と表わせば中央の欄が示される。以降の説明でマトリクス表の中の欄を指定する場合にはたとえば１×１の欄といった記載をして表１のいずれかの欄を表わす。
【００３４】
なお、マトリクス表の列側を指定する項目の欄にはカムピン１２１ａが、行側の項目の欄にはカムピン１２１ｂと記されている。表中の項目カムピン１２１ａと項目カムピン１２１ｂにはそれぞれ副題としてカム溝１と端子ＴＥ１と端子ＴＥ２という項目、カム溝２と端子ＴＥ３と端子ＴＥ４という項目がそれぞれ記されており、その項目のいずれにあたるかによりカムピン１２１ａ，１２１ｂそれぞれがカム溝１１２，１１２にあるか、あるいはいずれかの端子を備える導体上にあるかが分かる。たとえば２×２の欄であれば、双方のカムピン１２１ａ，１２１ｂがカム溝から外れ、カムピン１２１ｂの方が端子ＴＥ１を有する導体部１１３ａ側に乗り上げ、カムピン１２１ｂの方が端子ＴＥ３を有する導体部１１４ａ側に乗り上げたことが示されている。つまり、カムピン１２１ｂがカム溝１ １１１に嵌入されている場合にはカム溝１という表記で、あるいはカムピン１２１ｂが外れて導体１１３ａ側に乗り上げている場合には端子ＴＥ１という表記で、同じく導体１１３ｂ側に乗り上げている場合には端子ＴＥ２という表記でそれぞれ示されている。
【００３５】
同様にカムピン１２１ａがカム溝２に嵌入されている場合にはカム溝２という表記で、あるいはカムピン１２１ａが外れて導体１１４ａ側に乗り上げている場合には端子ＴＥ３という表記で、導体１１４ｂ側に乗り上げている場合には端子ＴＥ４という表記でそれぞれ示されている。
【００３６】
表１の１×１の欄に示すようにカム溝１ １１１、カム溝２ １１２双方ともカムピン１２１ａ，１２１ｂが嵌入されていれば、可変抵抗器ＶＲ１の最小抵抗値１Ωと可変抵抗器ＶＲ２の最小抵抗値１Ωとが加算された２Ωから可変抵抗器ＶＲ１の最大抵抗値１０ＫΩと可変抵抗器ＶＲ２の最大抵抗値１０ＫΩとが加算された２０ＫΩまでの範囲の抵抗値が示され、図３のポテンショメータ１１００ａの出力端子ＯＵＴには下式１で示される電圧０．３１Ｖ〜２Ｖが出力電圧として出力される。
【００３７】
出力電圧＝Ｒａｄｄ／（３０＋Ｒａｄｄ）×５ 式１
図３中の符合Ｒａｄｄは、カムピン１２１ａ側が可変抵抗ＶＲ１、端子ＴＥ１、端子ＴＥ２のいずれかに接続されて、カムピン１２１ｂ側が可変抵抗ＶＲ２、端子ＴＥ３、端子ＴＥ４のいずれかに接続されて、ＶＲ１、Ｒ１、Ｒ２のいずれかとＶＲ２、Ｒ３、Ｒ４のいずれかが直列に接続されたときの合成抵抗値を示している。
【００３８】
双方のカムピン１２１ａ，１２１ｂがカム溝１ １１１およびカム溝２ １１２にそれぞれ嵌入され、正常に動作している場合には表１の１×１の欄に示された抵抗値がポテンショメータ１１００ａで検出され、（）内に示した電圧がポテンショメータの出力端子ＯＵＴから出力される。表１に示されたマトリクス表のうち、表１の１×１欄以外の欄には二つのカムピンのうち、いずれかあるいは双方が外れた状態が示されている。表１の１×１の欄以外で示される状態を説明する。
【００３９】
まず表１の１×２の欄について説明する。この欄ではカムピン１２１ｂが導体部１１３ａに乗り上げ、カムピン１２１ａがそのままカム溝２ １１１に嵌入された状態が示されている。このときには導体１１３ａ側の端子ＴＥ１にカムピン１２１ｂが接続され固定抵抗Ｒ１の抵抗値７０ＫΩとカムピン１２１ａにより検出される１Ωから１０ＫΩまでのいずれかの抵抗値とが加算された値がＲａｄｄとして示される。したがって、抵抗値７０〜８０ＫΩがＲａｄｄとして示される。このときには式１で算出される出力電圧３．５Ｖ〜３．６ＶがＯＵＴ端子から出力される。
【００４０】
次に表１の１×３の欄について説明する。この欄ではカムピン１２１ｂが導体部１１３ｂに乗り上げ、カムピン１２１ａがそのままカム溝１１１に嵌入されている状態が示されている。このときには導体部１１３ｂの端子ＴＥ２にカムピン１２１ａが接続されてカムピン１２１ａが可変抵抗ＶＲ２に接続される。したがって固定抵抗Ｒ２の抵抗値１３０ＫΩと、カム溝２ １１１の抵抗体１１１ａで示される可変抵抗値１Ωから１０ＫΩまでのいずれかの抵抗値とが加算された抵抗値１３０〜１４０ＫΩがＲａｄｄとして示される。このときには式１で算出される出力電圧４．０６Ｖ〜４．１ＶがＯＵＴ端子から出力される。
【００４１】
次に２×１の欄について説明する。この欄ではカムピン１２１ａ側が導体部１１４ａに乗り上げ、カムピン１２１ａがそのままカム溝１１１に嵌入されている状態が示されている。
【００４２】
このときにはカムピン１２１ｂが可変抵抗器ＶＲ１側に接続されてカムピン１２１ａが導体部１１４ａの端子ＴＥ３に接続される。したがって固定抵抗Ｒ３の抵抗値３０ＫΩと、カム溝の抵抗体で示される１Ωから１０ＫΩまでのいずれかの抵抗値とが加算された抵抗値３０〜４０ＫΩがＲａｄｄとして示される。このときには式１で算出される出力電圧２．５Ｖ〜２．９ＶがＯＵＴ端子から出力される。
【００４３】
次に３×１の欄について説明する。この欄ではカムピン１２１ａが導体部１１４ｂに乗り上げ、カムピン１２１ｂ側がそのままカム溝１１１に嵌入されている状態が示されている。
【００４４】
このときにはカムピン１２１ｂが可変抵抗器ＶＲ１に接続されてカムピン１２１ａが導体部１１４ｂの端子ＴＥ４に接続される。したがって固定抵抗Ｒ４の抵抗値５０ＫΩと、カム溝１ １１２側の抵抗体１１２ｂで示される１Ωから１０ＫΩまでのいずれかの抵抗値とが加算された抵抗値５０〜６０ＫΩがＲａｄｄとして示される。このときには式１で算出される出力電圧３．１Ｖ〜３．３ＶがＯＵＴ端子から出力される。
【００４５】
ここまでは二つのカムピン１２１ａ，１２１ｂのいずれかかが導体に乗り上げた場合である。しかし二つのカムピン１２１ａ，１２１ｂが双方カム溝１１１，１１２から外れることもある。
【００４６】
表１の２×２、２×３、３×２、３×３の欄には双方のカムピン１２１ａ，１２１ｂが外れ、いずれかの導体部にそれぞれ外れたカムピンが乗り上げた状態が４通り示されている。
【００４７】
まず、表１の２×２の欄を説明する。カムピン１２１ｂ側が導体部１１４ａ側に外れ、カムピン１２１ａが導体部１１３ａ側に外れた状態が示されている。このときにはカムピンの一方が導体部の端子ＴＥ１に接続され、カムピンの他方が導体部の端子ＴＥ３に接続される。したがって固定抵抗Ｒ１の抵抗値７０ＫΩと、固定抵抗Ｒ３の抵抗値３０ＫΩとが加算された抵抗値１００ＫΩがＲａｄｄとして示される。このときには式１で算出される出力電圧３．８ＶがＯＵＴ端子から出力される。
【００４８】
次に表１の２×３の欄を説明する。カムピン１２１ｂ側が導体部１１４ａ側に外れ、カムピン１２１ａ側が導体部１１３ｂ側に外れた状態が示されている。このときにはカムピン１２１ａが導体部の端子ＴＥ２に接続され、カムピン１２１ｂが導体部１１４ａの端子ＴＥ３に接続される。したがって固定抵抗Ｒ２の抵抗値１３０ＫΩと、固定抵抗Ｒ３の抵抗値３０ＫΩとが加算された抵抗値１６０ＫΩがＲａｄｄとして示される。このときには式１で算出される出力電圧４．２ＶがＯＵＴ端子から出力される。
【００４９】
次に表１の３×２の欄を説明する。カムピン１２１ｂが導体部１１４ｂ側に外れ、カムピン１２１ａが導体部１１３ｂ側に外れた状態が示されている。このときにはカムピン１２１ｂが導体部の端子ＴＥ１に接続され、カムピン１２１ａが導体部の端子ＴＥ４に接続される。したがって固定抵抗Ｒ１の抵抗値７０ＫΩと、固定抵抗Ｒ４の抵抗値５０ＫΩとが加算された抵抗値１２０ＫΩがＲａｄｄとして示される。このときには式１で算出される出力電圧４．０ＶがＯＵＴ端子から出力される。
【００５０】
最後に表１の３×３の欄を説明する。カムピン１２１ｂ側が導体部１１４ａ側に外れ、カムピン１２１ａ側が導体部１１３ｂ側に外れた状態が示されている。このときにはカムピン１２１ｂが導体部の端子ＴＥ２に接続され、カムピン１２１ａが導体部１１４ｂの端子ＴＥ４に接続される。したがって固定抵抗Ｒ２の抵抗値１３０ＫΩと、固定抵抗Ｒ４の抵抗値５０ＫΩとが加算された抵抗値１８０ＫΩがＲａｄｄとして示される。このときには式１で算出される出力電圧４．３ＶがＯＵＴ端子から出力される。
【００５１】
このようにカムピンの状態に応じて区別された抵抗値により９通りの異なる電圧が出力され、どのようなカムピン外れであるかが特定される。このようにしてカムピンの状態が特定されたら、カム筒をカムピンがカム溝に嵌入される方向に回転させれば、カムピンがカム溝に嵌入される。
【００５２】
図４は図３のポテンショメータ１１００ａおよびカムピンはずれ検出回路１１０ａを備えた駆動部の構成ブロック図である。
【００５３】
カメラ内部にはＣＰＵ１３１が配備されており、そのＣＰＵ１３１によりカム筒１１０の駆動回路１３４が制御されている。そのＣＰＵ１３１には処理の手順を示すプログラムが格納されているＲＯＭ１３２と、処理中の変数が一時記憶されるＲＡＭ１３３とが備えられており、ＲＯＭ１３２に格納されているプログラムにしたがって処理が行なわれる。ズームレバー１０５の操作に応じた操作信号がＣＰＵ１３１に入力されると、ＣＰＵ１３１ではＲＯＭ１３２に格納されているプログラムにしたがってその入力された操作信号に基づき駆動回路１３４にカム筒１１０の駆動指示が発せられる。このＣＰＵ１３１からの駆動指示に応じて駆動回路１３４ではカム筒１１０が回転駆動される。カム筒１１０が回転駆動されると、カムピンがカム溝に沿って動き、カムピンの位置に応じてカムピンで検出される抵抗値が変化して、ポテンショメータおよびカムピン外れ検出回路１１０ａから出力される電圧が変化する。この変化する電圧がカムピンの絶対位置を示す信号としてＣＰＵ１３１に入力される。このＣＰＵ１３１にはアナログ入力部が備えられており、そのアナログ入力部でアナログ信号がデジタル信号に変換されて、デジタル信号になってＣＰＵ１３１に入力され、この入力された電圧に基づいてＣＰＵ１３１ではレンズの絶対位置すなわちズームポジションの検出が行なわれる。このときにはズームポジションに応じた電圧がＣＰＵに入力されているので、落下などによりズームポジションに変化があった場合には落とす前のレンズの位置と落とした後のレンズの位置とが電圧により検出可能である。このようにすると本実施形態のカメラに落下の衝撃が加えられ、レンズ鏡胴内のレンズの位置が変化したとしてもその位置がすぐに分かる。レンズの位置に変化があった場合にはズームレバー１０５の操作位置にあわせて、レンズ鏡胴内のレンズを動かすように駆動回路１３４でカム筒１１０が回転駆動され、所定のズームポジションにそのレンズが駆動される。
【００５４】
図５はズームレバー１０５の操作に応じてカム筒１１０が駆動されるときのフローチャートである。
【００５５】
ステップＳ５１ではズームレバー１０５が操作されていたら、駆動回路１３４にカム筒の駆動信号が供給される。駆動回路１３４ではこの駆動指令に基づいてカム筒１１０を回転駆動する。
【００５６】
そのときにはステップＳ５２でポテンショメータおよびカムピン外れ検出回路１１０ａのポテンショメータ１１００ａ側から出力される電圧に基づいてレンズの絶対位置（ズームポジション）がＣＰＵで検出される。ステップＳ５３でズームレバー１０５が操作中であるか否かが判定され、Ｙｅｓと判定されたら、ステップＳ５１へ戻され、カム筒が回転駆動され、そのカム筒の回転に応じてポテンショメータからの出力電圧が繰り返し検出され、レンズの絶対位置（ズームポジション）が検出される。
【００５７】
ステップＳ５３でＮｏと判定されたら、カム筒の回転駆動を停止してレンズ鏡胴内のレンズがズームレバー１０５の操作が終了した時点の位置に保持される。このときにはポテンショメータから出力された電圧の値がレンズの絶対位置（ズームポジション）を示す信号としてＣＰＵ内のたとえばＲＡＭに一旦記憶される。
【００５８】
本実施形態のカメラではカメラが落下して撮影光学系内のレンズの位置が変化しても、カメラが落下する前のレンズの位置にレンズを配置することができるように、ポテンショメータにより絶対位置が検出されている。カメラが落下する前にズームレバーが操作されてカム筒が駆動されているときのポテンショメータの出力電圧の値は前述したようにＲＡＭに保持されているのでカメラが落下してレンズの位置が変化した場合にはそのＲＡＭに保持された電圧と落下後のポテンショメータから出力される電圧とが比較されて、異なる電圧が検出された場合にはＲＡＭ１３３に保持されている電圧になるようにカム筒１１０を駆動回路１３４で回転駆動すれば、カムピン１２１ａ，１２１ｂの位置すなわちレンズの位置を修正することができる。このようにポテンショメータ１１００ａからその変化状態に応じた電圧がＣＰＵに入力されるのでカメラが落下した後でカムピンの位置が変化していてもすぐにその変化が検出される。
【００５９】
図６はそれぞれのズームポジションに応じたポテンショメータの出力電圧の変化を示した図である。図６の横軸には１から９までのズームポジションを、縦軸にはポテンショメータの出力電圧を示してある。
【００６０】
図６に示すように各ズームポジションに応じて異なる電圧が出力され、レンズの絶対位置が特定される。ズームポジション１であれば０．３１Ｖ、ズームポジション９であれば１，９Ｖの電圧がポテンショメータのＯＵＴ端子に出力される。ズームレバーが操作され、操作が終了した時点の電圧を記憶しておけば、落下したときにレンズの位置が変化したかどうかがすぐに分かる。
【００６１】
図７はカムピンをカム溝に復帰させるときのフローチャートである。
【００６２】
ステップＳ７１ではポテンショメータおよびカムピンはずれ検出回路１１０ａのＯＵＴ端子に出力される電圧が検出される。次のステップＳ７２でその検出された値が２Ｖ以下であるかどうかが判定される。このステップＳ７２でポテンショメータが正常に作動してＹｅｓと判定されたら、次のステップＳ７３で図５のフローチャートが実行される。ステップＳ７２ででＮｏと判定されたら、次のステップＳ７４で別表（表１）に示した１×１の欄以外の欄で示される８通りの状態のうち、いずれの状態であるか（カムピンがどの導体部に乗り上げたか）が検出される。表１に示したようにそれぞれの状態に応じて異なる電圧がポテンショメータおよびカムピンはずれ検出回路１１０ａから出力され、その電圧の値によってカムピンそれぞれがどの導体部に乗り上げているかがＣＰＵにより判別される。このフローチャート中ではカムピンそれぞれがどの導体部に乗り上げているかを判別することを乗り上げピン検出と記し、その乗り上げたカムピンを乗り上げピンと記してある。次のステップＳ７５ではカムピンをカム溝に復帰させるための回転筒の回転方向が定められる。
【００６３】
次のステップＳ７６ではＣＰＵから駆動回路に回転指示が発せられ、カム筒が所定の時間（ここでは５００ｍｓ）、回転駆動される。このステップＳ７６でカムピンをカム溝に嵌入する作業が行なわれている。
【００６４】
次のステップＳ７７でポテンショメータ１１００ａのＯＵＴ端子から出力される電圧が２Ｖ以下であるかどうかが判定され、このステップＳ７７でＹｅｓと判定されたら次のステップＳ７８でカムピンが正常復帰したとＣＰＵに認識される。
【００６５】
ステップＳ７７でＮｏと判定されたらステップＳ７９へ移行し、カムピンが嵌入されなかったとしてエラー処理たとえばズームエラーであることを表示することなどが行なわれる。
【００６６】
以上説明したようにレンズ鏡胴が繰出されたまま、落下してレンズ鏡胴に衝撃が加えられ、レンズ鏡胴内のレンズ位置が動いたとしても、ポテンショメータで絶対位置が検出されているので、ズームレバーの操作に応じた位置にレンズを復帰させることができる。さらにポテンショメータ（レンズ位置検出回路）とともにカムピンはずれ検出回路が備えられているので、カムピンが外れたとしてもカム筒が回転駆動され、カムピンをカム溝に復帰させることができるので、修理をわざわざ行なわなくてもこのカメラを正常に動作させることができる。またカム筒が回転駆動されても、カムピンがカム溝に復帰しなかった場合にはズームエラーが表示され、‘カムピンが外れている’という故障内容をユーザに示唆することができる。
【００６７】
なお、本実施形態ではカム溝が二つ備えられた例を説明したが本発明はこれによらず、カム溝およびカムピンが１つであっても良いし、カム溝が二つ以上あっても良い。
【００６８】
【発明の効果】
以上、説明したように、本発明のカメラによれば、簡単な機構でレンズ鏡胴内のレンズの絶対位置を精度良く検出することができ、かつ低廉なカメラを提供することができる。
【図面の簡単な説明】
【図１】本発明の一実施形態であるカメラの外観図である。
【図２】図１のレンズ鏡胴に配設されるカム筒とレンズ保持枠の構成を示す図である。
【図３】カムピンと、カム溝に設けられた抵抗体とで構成されたポテンショメータの等価回路を示す図である
【図４】カム筒を駆動する駆動部の構成ブロック図である。
【図５】ズームレバーが操作されたときの処理を示すフローチャートである。
【図６】ズームポジションとポテンショメータの出力電圧との関係を示す図である。
【図７】カムピン外れが起きたときの処理を示すフローチャートである。
【符号の説明】
１００ デジタルカメラ
１０１ レンズ鏡胴
１０５ ズームレバー
１１０ カム筒
１１０ａ ポテンショメータおよびカムピン外れ検出回路
１１００ａ ポテンショメータ
１１１ １１２ カム溝
１１１ａ １１２ａ 抵抗体
１１３ａ １１３ｂ 導体
１１４ａ １１４ｂ 導体
１２０ レンズ保持枠
１２１ａ カムピン
１２１ｂ カムピン
１３０ 駆動部
１３１ ＣＰＵ
１３２ ＲＯＭ
１３３ ＲＡＭ
１３４ 駆動回路[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a camera that includes a photographic optical system that includes a plurality of lenses and that has a variable focal length and that captures subject light that has passed through the photographic optical system.
[0002]
[Prior art]
In some cameras, a lens barrel with a built-in photographing optical system is extended when photographing is performed and retracted when photographing is not performed.
[0003]
In some cases, the focal length is adjusted by extending the lens barrel in response to a zooming operation such as a zoom lever. In such a camera, the rotation of the motor is received by the cam mechanism, and the focal length is adjusted by moving the lens barrel back and forth in the optical axis direction by the cam mechanism to move the lens position. When shooting with such a camera, the camera may be dropped while the lens barrel is extended due to carelessness of the user. Even if the camera body has sufficient strength so that it does not break even if dropped, the position of the lens in the lens barrel may move due to the impact of the drop. In such a case, a change in the position of the lens must be detected to correct the position (for example, Patent Document 1). Patent Document 1 introduces a technique for detecting the amount of rotation of a cam cylinder with an encoder and providing position detection means on the outer periphery of the cam cylinder to detect the absolute position of the photographic optical system according to both detection results. .
[0004]
[Patent Document 1]
JP-A-6-214282
[0005]
[Problems to be solved by the invention]
In Patent Document 1, in order to detect the absolute position of the lens in the lens barrel, a position detection means is required together with an encoder. If it does so, there will be a problem that the number of parts increases and it is expensive because it is complicated.
[0006]
In view of the above circumstances, an object of the present invention is to provide an inexpensive camera that can detect the absolute position of a lens with a simple mechanism.
[0007]
[Means for Solving the Problems]
The camera of the present invention that achieves the above object includes a photographing optical system with a variable focal length configured by a plurality of lenses, and a camera that performs photographing by capturing subject light that has passed through the photographing optical system.
A cam mechanism comprising a cam cylinder having a cam groove and a cam pin cam-engaged with the cam cylinder for moving at least one of the plurality of lenses for focal length adjustment;
A magnification changing operator for instructing adjustment of a focal length of the photographing optical system;
A drive source that rotationally drives the cam barrel in accordance with the operation of the magnification change instruction operator and adjusts the focal length of the photographing optical system,
The cam groove has a resistor whose resistance value is detected according to the insertion position of the cam pin through the cam pin,
The cam pin forms a sliding member that slides on the resistor to the cam groove, and includes a lens position detection circuit that detects a lens position based on a resistance value detected via the cam pin. It is characterized by.
[0008]
According to the camera of the present invention, a variable resistor is formed by a cam pin serving as a sliding member and a resistor provided in the cam groove, and based on a resistance value detected by the sliding member of the variable resistor. The absolute position of the lens in the lens barrel can be detected by the lens position detection circuit.
[0009]
Here, on both sides of the cam groove, a conductor or a resistor is provided at a position where the cam pin comes into contact when the cam pin is detached from the cam groove, and the cam groove is based on a resistance value detected through the cam pin. It is preferable that a cam pin misalignment detection circuit for detecting that the cam pin is disengaged is provided.
[0010]
Thus, when the cam pin detachment detection circuit detects that the cam pin that is the sliding member of the variable resistor has been removed, the cam pin detachment detection circuit indicates that the cam pin has been removed even if the cam pin is detached due to a drop impact. Can be detected.
[0011]
Furthermore, it is preferable that the cam pin misalignment detection circuit specifies a side where the cam pin is detached by detecting a different resistance value depending on the side of the cam groove on which the cam pin is detached.
[0012]
In this way, when a different resistance value is detected via the cam pin depending on which side of the cam groove is removed, it is determined to which side the cam pin is removed, and the cam cylinder is rotated to rotate the cam pin. It can be returned to the groove. Further, when the cam pin returns to the cam groove, the absolute position of the cam pin is detected by the lens position detection circuit as described above, so that the position of the lens is immediately known.
[0013]
The cam cylinder has a plurality of cam grooves and the cam mechanism has a plurality of cam pins fitted into the cam grooves, and the cam pin deviation detection circuit is in a state where the cam pins are fitted into the cam grooves. Even if it exists, even if it is in the state which removed in any one of the cam groove both sides in which the cam pin is inserted, the distinguished resistance value is detected.
[0014]
Even if this camera has a plurality of cam grooves and a plurality of cam pins, each of the plurality of cam pins is inserted into each of the plurality of cam grooves, or any one of the plurality of cam pins is detached from each cam groove. The state of the cam pin is detected by the resistance value distinguished by the cam pin detachment detection circuit, which state is the state, or each of the plurality of cam pins is out of the cam groove. Is specified. Then, even if at least one of the plurality of cam pins is removed from at least one of the plurality of cam grooves, the cam cylinder is rotated so that the removed cam pin is inserted into the cam groove. The cam pin can be returned to the original state.
[0015]
In other words, the drive source may be configured to rotate the cam cylinder in a direction in which the cam pin is reinserted into the cam groove based on the fact that the cam pin detachment detection circuit has specified the side from which the cam pin has been removed.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0017]
FIG. 1 is an external view of a camera showing an embodiment of the present invention. FIG. 1A is a front view, and FIG. 1B is a rear view.
[0018]
As shown in FIG. 1A, a lens barrel 101 is provided. The lens barrel 101 is retracted when shooting is not performed, and is extended when shooting is performed.
[0019]
FIG. 1 (a) shows a state in which it is fed out. A flash light emitting unit 102 is provided above the lens barrel 101, and flash light is emitted from the flash light emitting unit 102 in accordance with subject brightness. A release button 103 is provided on the upper surface of the camera body. When the release button 103 is pressed, shooting is performed. A finder objective window 104a is also provided, and the subject can be confirmed by looking through the eyepiece of the finder on the back.
[0020]
As shown in FIG. 1B, a zoom lever 105 and a display screen 106 are provided on the back surface. The display screen 106 displays a subject image in a direction in which the tip of the lens barrel 101 in which the photographing optical system is built is directed. When the zoom lever 105 is operated, the lens barrel 101 is further extended from a predetermined position, and some lenses in the photographing optical system built in the lens barrel 101 move together with the lens barrel 101. Adjust the focal length. A viewfinder eyepiece 104 b is also provided on the side of the display screen 106.
[0021]
FIG. 2 is a diagram showing the configuration of the cam barrel and the lens holding frame disposed in the lens barrel 101. As shown in FIG. FIG. 2A shows a cam cylinder, a cam groove provided in the cam cylinder, a resistor provided in the cam groove, a wiring state between the resistor, a power source, and a ground, and both sides of the cam groove. FIG. 2B is a diagram illustrating a state in which the lens holding frame and the cam pins included in the lens holding frame are connected by a conductor and are short-circuited.
[0022]
As shown in FIG. 2A, the cam cylinder 110 is provided with two cam grooves 111 and 112, and the cam grooves 111 and 112 are provided with resistors 111a and 112a, respectively. Since the resistors 111a and 112a are provided in the two cam grooves 111 and 112, respectively, in the following description, one will be described as the cam groove 1112 and the other as the cam groove 2 111. Each of the resistors 112a and 111a provided in both the cam groove 1 112 and the cam groove 2 111 detects a resistance value of 1Ω to 10KΩ depending on the position of the cam pins 121a and 121b. The detected resistance value changes depending on the position and the wiring state of the resistor 111.
[0023]
Here, one end side (upper end side in FIG. 2A) of the resistor 111a provided in the cam groove 211 is connected to the ground, and the other end side (lower end side in FIG. 2A) of the resistor 111a. The other end side (not shown) of the resistor 112a is connected to the power source 5V by connecting one end side (the lower end side in FIG. 2A) of the resistor 112a provided in the cam groove 1112. Is open. Therefore, a current flows from the power source side to the ground side via the resistor 112a provided in the cam groove 2112 and further through the resistor 111a provided in the cam groove 2111.
[0024]
The resistance value from the ground side of the resistor 111a on the cam groove 2 111 side to the cam pin 121a is the same as the resistance value from the power supply side on the cam groove 1112 side to the cam pin 121b. For example, as shown in FIG. 2, when the position of the cam pin 121b is at the end on the power supply side on the cam groove 1 side and the end on the ground side on the cam groove 2 side, resistance values of 1Ω and 1Ω are shown, When the cam pins 121a and 121b are at opposite ends of the cam grooves 111 and 112, respectively, a resistance value of 10 KΩ and 10 KΩ is shown.
[0025]
In addition, conductor portions 113a and 113b are provided on both sides of the cam groove 1112, and similarly, conductor portions 114a and 114b are provided on both sides of the cam groove 2111, respectively. When the cam pin 121b on the cam groove 1112 side comes off and rides on either of the conductor portions 113a and 113b, a current flows from the power source via the resistor R1 or R2 connected to each conductor, and the cam pin 121a side comes off. When riding on one of the conductor portions 114a and 114b, a current flows into the ground via the resistor R3 or R4. The terminals TE1 and TE2 are provided on the conductor portions 113a and 113b on both sides of the cam groove 1112, respectively, and the terminals TE3 and TE4 are provided on the conductor portions 114a and 114b on both sides of the cam groove 2111, respectively. Among these terminals, the terminal TE1 and the terminal TE2 are connected to the power supply 5V via the resistors R1 and R2, respectively, and the terminals TE3 and TE4 are connected to the ground via the resistors R3 and R4, respectively.
[0026]
Further, the cam pins 121a and 121b provided on the lens holding frame 120 are short-circuited by a conductor 122 provided along the outer periphery of the lens holding frame 120. These cam pins 121a and 121b are shown in FIG. Are inserted into the cam grooves 111 and 112, respectively. When the cam pins 121a and 121b are stopped at any position of the resistors 111a and 112a provided in the cam grooves 111 and 112, resistance values corresponding to those positions are detected. Each of the shorted cam pins 121a and 121b functions as a sliding member, and when the resistors 111a and 112a provided in the cam groove 1 111 and the cam groove 2 112 are slid, the resistance value at the position where the cam pin stops is detected. Is done. That is, each resistor provided in the cam groove and the cam pin each function as a variable resistor.
[0027]
FIG. 3 is a diagram showing an equivalent circuit of the potentiometer and cam pin misalignment detection circuit 110a composed of these variable resistors and fixed resistors. Thus, when the cam pin acts as a sliding member and the cam pin slides along the resistor provided in the cam groove, the resistance value detected by the cam pin changes and the resistance value according to the position of the cam pin Is detected by the cam pin. That is, the cam groove portion and the cam pin function as a potentiometer whose absolute position is determined by a resistance value detected by the cam pin.
[0028]
This potentiometer includes a fixed resistor having a resistance value of 30 KΩ, a variable resistor VR1 in which the cam pin 121a serves as a sliding member, a variable resistor VR2 in which the cam pin 121b serves as a sliding member, and an output terminal OUT. As shown in FIG. 3, one end of a fixed resistor of 30 KΩ is connected to the power source, here 5 V, and one end of a variable resistor VR2 formed on the cam groove 2 side is connected to the ground.
[0029]
Since the resistance values of the resistors in the cam groove 1 and the cam groove 2 change depending on the stop positions of the cam pins 121a and 121b, the value of the voltage output to the OUT terminal changes. If this voltage value is input to an A / D converter of the CPU, which will be described later, the voltage output from the output terminal OUT changes depending on the resistance value indicated by the potentiometer, and the position of the cam pin can be known according to the voltage. That is, the portion surrounded by the dotted line in FIG. 3 functions as a potentiometer 1100a. This potentiometer 1100a corresponds to the lens position detection circuit according to the present invention.
[0030]
This equivalent circuit also shows a cam pin deviation detection circuit that can detect the direction in which the cam pins are disengaged when the cam pins 121a and 121b are disengaged from the cam grooves.
[0031]
The cam pin detachment detection circuit shown in the equivalent circuit can detect eight types of cam pin detachment states in addition to the functioning of the potentiometer without the cam pin detaching.
[0032]
[Table 1]

[0033]
Table 1 is a matrix table. When the potentiometer operates without the cam pin being detached and the absolute position of the lens is detected based on the stop position of the cam pin, one is used, and when either of the two cam pins is detached from the conductor part side. Nine or nine states are shown, respectively, in the case of four or when both cam pins are disengaged on either conductor side. Each column in Table 1 is distinguished by a row number and a column number, and if any one of the row numbers (1 to 3) and any one of the column numbers (1 to 3) is designated, any of the nine These fields are specified. For example, if the row number and the column number are represented by 1 × 1, the upper left column of the matrix table is shown, and if it is represented by 2 × 2, the middle column is shown. In the following description, when a column in the matrix table is designated, for example, a column of 1 × 1 is described to indicate any column in Table 1.
[0034]
It should be noted that the cam pin 121a is described in the item column for designating the column side of the matrix table, and the cam pin 121b is described in the column for the item on the row side. In the table, the item cam pin 121a and the item cam pin 121b are respectively subtitled items of cam groove 1, terminal TE1, and terminal TE2, and item of cam groove 2, terminal TE3, and terminal TE4, respectively. Thus, it can be seen whether the cam pins 121a and 121b are in the cam grooves 112 and 112 or on a conductor having one of the terminals. For example, in the 2 × 2 column, both cam pins 121a and 121b are disengaged from the cam groove, and the cam pin 121b rides on the conductor portion 113a having the terminal TE1, and the cam pin 121b has a conductor portion 114a having the terminal TE3. It is shown that it has ridden on the side. That is, when the cam pin 121b is fitted in the cam groove 1111, it is expressed as a cam groove 1, or when the cam pin 121b is detached and rides on the conductor 113a side, it is expressed as a terminal TE1. When the vehicle is on board, it is indicated by the notation of terminal TE2.
[0035]
Similarly, when the cam pin 121a is fitted into the cam groove 2, the cam groove 2 is indicated, or when the cam pin 121a is disengaged and rides on the conductor 114a side, the terminal TE3 is indicated on the conductor 114b side. Are indicated by the notation of terminal TE4.
[0036]
As shown in the 1 × 1 column of Table 1, if both cam groove 1 111 and cam groove 2 112 are fitted with cam pins 121a and 121b, the minimum resistance value 1Ω of variable resistor VR1 and the minimum value of variable resistor VR2 The potentiometer 1100a shown in FIG. 3 shows a resistance value ranging from 2Ω obtained by adding the resistance value 1Ω to 20 KΩ obtained by adding the maximum resistance value 10KΩ of the variable resistor VR1 and 10KΩ of the variable resistor VR2. A voltage of 0.31 V to 2 V represented by the following expression 1 is output as an output voltage to the output terminal OUT of the output terminal OUT.
[0037]
Output voltage = Radd / (30 + Radd) × 5 Equation 1
The sign Radd in FIG. 3 is such that the cam pin 121a side is connected to any one of the variable resistor VR1, the terminal TE1, and the terminal TE2, and the cam pin 121b side is connected to any one of the variable resistor VR2, the terminal TE3, and the terminal TE4. The combined resistance value when any of R1, R2 and any of VR2, R3, R4 are connected in series is shown.
[0038]
When both cam pins 121a and 121b are inserted into the cam groove 1 111 and the cam groove 2 112 and are operating normally, the resistance value shown in the 1 × 1 column of Table 1 is detected by the potentiometer 1100a. The voltage shown in parentheses is output from the output terminal OUT of the potentiometer. Of the matrix table shown in Table 1, columns other than the 1 × 1 column in Table 1 show a state in which one or both of the two cam pins are disconnected. The states shown in Table 1 other than the 1 × 1 column will be described.
[0039]
First, the 1 × 2 column in Table 1 will be described. In this column, the cam pin 121b rides on the conductor 113a, and the cam pin 121a is inserted into the cam groove 2111 as it is. At this time, the cam pin 121b is connected to the terminal TE1 on the conductor 113a side, and a value obtained by adding the resistance value 70KΩ of the fixed resistor R1 and any resistance value from 1Ω to 10KΩ detected by the cam pin 121a is indicated as Radd. Therefore, a resistance value of 70 to 80 KΩ is indicated as Radd. At this time, the output voltage 3.5V to 3.6V calculated by Expression 1 is output from the OUT terminal.
[0040]
Next, the 1 × 3 column in Table 1 will be described. In this column, a state where the cam pin 121b rides on the conductor portion 113b and the cam pin 121a is inserted into the cam groove 111 as it is is shown. At this time, the cam pin 121a is connected to the terminal TE2 of the conductor portion 113b, and the cam pin 121a is connected to the variable resistor VR2. Therefore, the resistance value 130 to 140 KΩ obtained by adding the resistance value 130 KΩ of the fixed resistor R2 and any one of the variable resistance values 1Ω to 10 KΩ indicated by the resistor 111a of the cam groove 2111 is indicated as Radd. At this time, the output voltage of 4.06V to 4.1V calculated by Expression 1 is output from the OUT terminal.
[0041]
Next, the 2 × 1 column will be described. In this column, the cam pin 121a side rides on the conductor portion 114a, and the cam pin 121a is inserted into the cam groove 111 as it is.
[0042]
At this time, the cam pin 121b is connected to the variable resistor VR1 side, and the cam pin 121a is connected to the terminal TE3 of the conductor portion 114a. Therefore, the resistance value 30 to 40 KΩ obtained by adding the resistance value 30 KΩ of the fixed resistor R3 and any one of the resistance values 1 to 10 KΩ indicated by the cam groove resistor is indicated as Radd. At this time, an output voltage of 2.5 V to 2.9 V calculated by Expression 1 is output from the OUT terminal.
[0043]
Next, the 3 × 1 column will be described. In this column, a state in which the cam pin 121a rides on the conductor portion 114b and the cam pin 121b side is directly inserted into the cam groove 111 is shown.
[0044]
At this time, the cam pin 121b is connected to the variable resistor VR1, and the cam pin 121a is connected to the terminal TE4 of the conductor portion 114b. Therefore, the resistance value 50-60 KΩ obtained by adding the resistance value 50 KΩ of the fixed resistor R4 and any one of the resistance values from 1Ω to 10 KΩ indicated by the resistor 112b on the cam groove 1112 side is indicated as Radd. At this time, the output voltage 3.1V to 3.3V calculated by Expression 1 is output from the OUT terminal.
[0045]
This is the case where one of the two cam pins 121a and 121b rides on the conductor. However, the two cam pins 121a and 121b may be disengaged from the cam grooves 111 and 112.
[0046]
In the column of 2 × 2, 2 × 3, 3 × 2, and 3 × 3 in Table 1, the four cam pins 121a and 121b are disengaged, and the disengaged cam pins are mounted on any of the conductor portions. ing.
[0047]
First, the 2 × 2 column in Table 1 will be described. The state where the cam pin 121b side is disengaged toward the conductor portion 114a and the cam pin 121a is disengaged toward the conductor portion 113a is shown. At this time, one of the cam pins is connected to the terminal TE1 of the conductor portion, and the other of the cam pins is connected to the terminal TE3 of the conductor portion. Therefore, the resistance value 100 KΩ obtained by adding the resistance value 70 KΩ of the fixed resistor R1 and the resistance value 30 KΩ of the fixed resistor R3 is indicated as Radd. At this time, the output voltage 3.8 V calculated by Expression 1 is output from the OUT terminal.
[0048]
Next, the 2 × 3 column in Table 1 will be described. A state where the cam pin 121b side is disengaged toward the conductor portion 114a and the cam pin 121a side is disengaged toward the conductor portion 113b is shown. At this time, the cam pin 121a is connected to the terminal TE2 of the conductor portion, and the cam pin 121b is connected to the terminal TE3 of the conductor portion 114a. Therefore, a resistance value 160KΩ obtained by adding the resistance value 130KΩ of the fixed resistor R2 and the resistance value 30KΩ of the fixed resistor R3 is indicated as Radd. At this time, the output voltage of 4.2 V calculated by Expression 1 is output from the OUT terminal.
[0049]
Next, the 3 × 2 column in Table 1 will be described. A state in which the cam pin 121b is disengaged toward the conductor portion 114b and the cam pin 121a is disengaged toward the conductor portion 113b is shown. At this time, the cam pin 121b is connected to the terminal TE1 of the conductor portion, and the cam pin 121a is connected to the terminal TE4 of the conductor portion. Therefore, the resistance value 120 KΩ obtained by adding the resistance value 70 KΩ of the fixed resistor R1 and the resistance value 50 KΩ of the fixed resistor R4 is indicated as Radd. At this time, the output voltage of 4.0 V calculated by Expression 1 is output from the OUT terminal.
[0050]
Finally, the 3 × 3 column in Table 1 will be described. A state where the cam pin 121b side is disengaged toward the conductor portion 114a and the cam pin 121a side is disengaged toward the conductor portion 113b is shown. At this time, the cam pin 121b is connected to the terminal TE2 of the conductor portion, and the cam pin 121a is connected to the terminal TE4 of the conductor portion 114b. Therefore, the resistance value 180 KΩ obtained by adding the resistance value 130 KΩ of the fixed resistor R2 and the resistance value 50 KΩ of the fixed resistor R4 is indicated as Radd. At this time, the output voltage 4.3 V calculated by Expression 1 is output from the OUT terminal.
[0051]
In this way, nine different voltages are output based on the resistance values distinguished according to the state of the cam pin, and what kind of cam pin disconnection is specified. When the state of the cam pin is specified in this way, the cam pin is inserted into the cam groove by rotating the cam cylinder in the direction in which the cam pin is inserted into the cam groove.
[0052]
FIG. 4 is a block diagram showing the configuration of a drive unit including the potentiometer 1100a and the cam pin deviation detection circuit 110a shown in FIG.
[0053]
A CPU 131 is provided inside the camera, and the drive circuit 134 of the cam cylinder 110 is controlled by the CPU 131. The CPU 131 is provided with a ROM 132 that stores a program indicating a processing procedure, and a RAM 133 that temporarily stores a variable being processed. Processing is performed according to the program stored in the ROM 132. When an operation signal corresponding to the operation of the zoom lever 105 is input to the CPU 131, the CPU 131 issues a drive instruction for driving the cam cylinder 110 to the drive circuit 134 based on the input operation signal in accordance with a program stored in the ROM 132. . In response to the drive instruction from the CPU 131, the drive cylinder 134 rotates the cam cylinder 110. When the cam cylinder 110 is driven to rotate, the cam pin moves along the cam groove, the resistance value detected by the cam pin changes according to the position of the cam pin, and the voltage output from the potentiometer and the cam pin disconnection detection circuit 110a is changed. Change. This changing voltage is input to the CPU 131 as a signal indicating the absolute position of the cam pin. The CPU 131 is provided with an analog input unit. An analog signal is converted into a digital signal by the analog input unit, and the digital signal is input to the CPU 131. Based on the input voltage, the CPU 131 detects the lens. The absolute position, that is, the zoom position is detected. At this time, since the voltage corresponding to the zoom position is input to the CPU, if there is a change in the zoom position due to a drop or the like, the position of the lens before dropping and the position of the lens after dropping can be detected by the voltage. It is. In this way, a drop impact is applied to the camera of the present embodiment, and even if the position of the lens in the lens barrel changes, the position can be immediately known. When the position of the lens changes, the cam cylinder 110 is rotationally driven by the drive circuit 134 so as to move the lens in the lens barrel in accordance with the operation position of the zoom lever 105, and the lens is moved to a predetermined zoom position. Is driven.
[0054]
FIG. 5 is a flowchart when the cam cylinder 110 is driven in accordance with the operation of the zoom lever 105.
[0055]
In step S51, if the zoom lever 105 is operated, a drive signal for the cam barrel is supplied to the drive circuit 134. The drive circuit 134 rotationally drives the cam cylinder 110 based on this drive command.
[0056]
At that time, in step S52, the absolute position (zoom position) of the lens is detected by the CPU based on the voltage output from the potentiometer 1100a side of the potentiometer and cam pin detachment detection circuit 110a. In step S53, it is determined whether or not the zoom lever 105 is being operated. If the determination is Yes, the process returns to step S51, the cam cylinder is driven to rotate, and the output voltage from the potentiometer according to the rotation of the cam cylinder. Are repeatedly detected, and the absolute position (zoom position) of the lens is detected.
[0057]
If it is determined No in step S53, the rotation of the cam barrel is stopped and the lens in the lens barrel is held at the position when the operation of the zoom lever 105 is completed. At this time, the value of the voltage output from the potentiometer is temporarily stored in, for example, a RAM in the CPU as a signal indicating the absolute position (zoom position) of the lens.
[0058]
In the camera of this embodiment, even if the camera falls and the position of the lens in the photographing optical system changes, the absolute position is adjusted by a potentiometer so that the lens can be arranged at the position of the lens before the camera falls. Has been detected. As described above, the output voltage value of the potentiometer when the zoom lever is operated and the cam cylinder is driven before the camera is dropped is held in the RAM, so the camera is dropped and the lens position is changed. In this case, the voltage held in the RAM and the voltage output from the potentiometer after the fall are compared, and if a different voltage is detected, the cam cylinder 110 is adjusted so that the voltage held in the RAM 133 is obtained. If the drive circuit 134 is rotationally driven, the positions of the cam pins 121a and 121b, that is, the positions of the lenses can be corrected. Thus, since the voltage according to the change state is input from the potentiometer 1100a to the CPU, even if the position of the cam pin is changed after the camera is dropped, the change is detected immediately.
[0059]
FIG. 6 is a diagram showing a change in the output voltage of the potentiometer according to each zoom position. In FIG. 6, the horizontal axis indicates the zoom position from 1 to 9, and the vertical axis indicates the output voltage of the potentiometer.
[0060]
As shown in FIG. 6, a different voltage is output according to each zoom position, and the absolute position of the lens is specified. A voltage of 0.31 V is output to the OUT terminal of the potentiometer when the zoom position is 1, and a voltage of 1,9 V is output when the zoom position is 9. If the voltage at the time when the zoom lever is operated and the operation is completed is stored, it can be immediately determined whether or not the lens position has changed when the zoom lever is dropped.
[0061]
FIG. 7 is a flowchart for returning the cam pin to the cam groove.
[0062]
In step S71, the voltage output to the OUT terminal of the potentiometer and cam pin deviation detection circuit 110a is detected. In the next step S72, it is determined whether or not the detected value is 2V or less. If the potentiometer operates normally in this step S72 and it is determined Yes, the flowchart of FIG. 5 is executed in the next step S73. If it is determined No in step S72, which of the eight states shown in the columns other than the 1 × 1 column shown in the separate table (Table 1) in the next step S74 (the cam pin is in the state). It is detected which conductor part). As shown in Table 1, different voltages are output from the potentiometer and the cam pin misalignment detection circuit 110a according to the respective states, and the CPU determines which conductor portion each cam pin rides on based on the voltage value. In this flowchart, determining which conductor portion each cam pin rides on is referred to as a ride-on pin detection, and the cam pin that has been run-up is described as a ride-on pin. In the next step S75, the rotation direction of the rotating cylinder for returning the cam pin to the cam groove is determined.
[0063]
In the next step S76, the CPU issues a rotation instruction to the drive circuit, and the cam cylinder is driven to rotate for a predetermined time (here, 500 ms). In step S76, an operation for fitting the cam pin into the cam groove is performed.
[0064]
In the next step S77, it is determined whether or not the voltage output from the OUT terminal of the potentiometer 1100a is 2V or less. If it is determined Yes in step S77, the CPU recognizes that the cam pin has returned to normal in the next step S78. The
[0065]
If it is determined No in step S77, the process proceeds to step S79, and error processing such as displaying a zoom error is performed on the assumption that the cam pin is not inserted.
[0066]
As described above, even if the lens barrel is dropped while being dropped and an impact is applied to the lens barrel, and the lens position in the lens barrel is moved, the absolute position is detected by the potentiometer. The lens can be returned to a position corresponding to the operation of the zoom lever. In addition, a cam pin detachment detection circuit is provided along with a potentiometer (lens position detection circuit), so that even if the cam pin is removed, the cam cylinder can be driven to rotate, and the cam pin can be returned to the cam groove. However, this camera can be operated normally. In addition, if the cam pin does not return to the cam groove even if the cam cylinder is driven to rotate, a zoom error is displayed, and the user can be informed of the failure content that “the cam pin is disconnected”.
[0067]
In this embodiment, an example in which two cam grooves are provided has been described. However, the present invention is not limited to this, and there may be one cam groove and one cam pin, or two or more cam grooves. good.
[0068]
【The invention's effect】
As described above, according to the camera of the present invention, the absolute position of the lens in the lens barrel can be accurately detected with a simple mechanism, and an inexpensive camera can be provided.
[Brief description of the drawings]
FIG. 1 is an external view of a camera according to an embodiment of the present invention.
2 is a diagram showing a configuration of a cam cylinder and a lens holding frame disposed in the lens barrel of FIG. 1. FIG.
FIG. 3 is a diagram showing an equivalent circuit of a potentiometer including a cam pin and a resistor provided in the cam groove.
FIG. 4 is a configuration block diagram of a drive unit that drives a cam cylinder.
FIG. 5 is a flowchart showing processing when a zoom lever is operated.
FIG. 6 is a diagram illustrating a relationship between a zoom position and an output voltage of a potentiometer.
FIG. 7 is a flowchart showing processing when cam pin disconnection occurs.
[Explanation of symbols]
100 digital camera
101 Lens barrel
105 Zoom lever
110 Cam cylinder
110a Potentiometer and cam pin disconnection detection circuit
1100a Potentiometer
111 112 Cam groove
111a 112a resistor
113a 113b conductor
114a 114b conductor
120 Lens holding frame
121a Cam pin
121b Cam pin
130 Drive unit
131 CPU
132 ROM
133 RAM
134 Drive circuit

Claims (4)

In a camera that includes a photographing optical system with a variable focal length composed of a plurality of lenses, and performs photographing by capturing subject light that has passed through the photographing optical system,
A cam mechanism comprising a cam cylinder having a cam groove and a cam pin cam-engaged with the cam cylinder for moving at least one of the plurality of lenses for adjusting the focal length;
A magnification changing operator for instructing adjustment of a focal length of the photographing optical system;
A drive source that rotates the cam barrel in response to an operation of the magnification change instruction operator and adjusts a focal length of the photographing optical system;
The cam groove has a resistor whose resistance value is detected according to the insertion position of the cam pin through the cam pin, and the cam pin constitutes a sliding member that slides on the resistor to the cam groove. And
A lens position detection circuit for detecting a lens position based on a resistance value detected via the cam pin ;
A conductor or resistor is provided at a position on both sides of the cam groove where the cam pin comes into contact with the cam pin when the cam pin is removed from the cam groove, and the cam groove is separated from the cam groove based on a resistance value detected via the cam pin. A camera comprising a cam pin misalignment detection circuit for detecting that a cam pin is detached . 2. The cam pin disengagement detection circuit is configured to identify a side where the cam pin is detached by detecting a different resistance value depending on a side of the cam groove on which the cam pin is detached. camera. The cam cylinder has a plurality of cam grooves and the cam mechanism has a plurality of cam pins fitted into the plurality of cam grooves, and the cam pin detachment detection circuit is in a state where the cam pins are fitted into the cam grooves. 3. The camera according to claim 2 , wherein the detected resistance value is detected even if the cam pin is disengaged on either side of the cam groove . Wherein the driving source is characterized in that in which rotates the cam barrel in a direction to fit the cam pin based on the side outside of the cam pin through the cam pin out detection circuit is identified again with the cam groove Item 2. The camera according to Item 2 .

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