JP3970691B2 - Lens drive device - Google Patents

Description

【００８８】
表１の（ａ）から（ｄ）には、本実施形態における３つの態様がそれぞれ示されており、（ａ）には、第１実施形態と同様の手順でレンズ枠を移動させる態様が、（ｂ）には、第１実施形態に対して、高負荷の下でもレンズ枠の移動が可能な態様が、（ｃ）および（ｄ）には、第１実施形態に対し、レンズ枠の移動を高速で行なうことが可能な態様が示されている。
【００８９】
（ａ）から（ｄ）には、時間の経過に対する、上部駆動シャフト、上部圧電素子、下部駆動シャフト、下部圧電素子、およびレンズ枠の各状態が示されている。
【００９０】
最初に、（ａ）に示されている、この第２実施形態において第１実施形態と同様の方法でレンズ枠を移動させる態様について説明する。
【００９１】
この態様では、上部駆動シャフトに対するレンズ枠の結合状態を切り替える上部圧電素子と下部圧電素子のうち下部圧電素子は常に非駆動状態に置かれるため、上部および下部の各駆動シャフトのうち下部シャフトは移動しない。したがって、この（ａ）に示される態様は、駆動するシャフトの位置が上下逆になっているものの第１実施形態と同様の手順および構成となっているので、これについての説明は省略する。
【００９２】
次に、（ｂ）に示されている、第１実施形態に対して、移動の手順については同じではあるものの高負荷の下のレンズ枠の移動が可能な態様について説明する。
【００９３】
この態様では、第１実施形態では、下方に備えられている１本の駆動シャフトに対して行われていた、駆動シャフトに対するレンズ枠の結合状態の切り替えが、上下に備えられた駆動シャフトそれぞれに対し、同時に、そして、同じ手順で行われている。これにより、この態様では、レンズ枠が、上部および下部駆動シャフト双方に固定することができるため、移動の基となるレンズ鏡胴内での駆動シャフトとの移動を、レンズ枠にかかっている高負荷に抗して行なうことが可能である。尚、この態様の動作説明については、図３においてした説明と重複するので省略する。
【００９４】
最後に、（ｃ）に示されている、第１実施形態に対し、レンズ枠の移動を高速で行なうことが可能な態様について説明する。
【００９５】
この態様では、（ｃ）に示されるように、上部駆動シャフト用圧電素子と下部シャフト用圧電素子は、互いに逆方向に動作すると共に、上部圧電素子と下部圧電素子も、互いに逆の結合状態でそれぞれの駆動ロッドに結合される。
【００９６】
図１３は、表１の（ｃ）に示される態様によるレンズ枠の移動の様子を示す図である。
【００９７】
図１３には、上部駆動シャフト用圧電素子と上部駆動シャフト、および、下部駆動シャフト用圧電素子と下部駆動シャフトが、上下２段の４つの状態（Ｃ１、Ｃ２、Ｃ４、およびＣ６）で示されており、レンズ枠は、これら上部および下部駆動シャフト上をカメラ前方方向に移動している。
【００９８】
以下、図１３を参照しながら、表１の（ｃ）に示される態様について説明する。
【００９９】
まず、（ｃ）の下方に示されるＣ１において、上部圧電素子が上部駆動シャフトに対し固定状態にされ、下部圧電素子が下部駆動シャフトに対し非駆動状態にされる。それからＣ２において、上部駆動シャフト用圧電素子が伸長され、逆に、下部駆動シャフト用圧電素子が短縮される。レンズ枠は、Ｃ１と比べ、上部駆動シャフト用圧電素子が伸長した分だけカメラ前方方向に移動する。次に、Ｃ３において双方の駆動シャフトが停止している間に、上部圧電素子が上部駆動シャフトに対し固定状態から非駆動状態にされ、下部圧電素子が下部駆動シャフトに対し非駆動状態から固定状態にされる。この状態で、今度はＣ４において、上部駆動シャフト用圧電素子が短縮し下部駆動シャフト用圧電素子が伸長すると、レンズ枠は、Ｃ２と比べ、下部駆動シャフト用圧電素子が伸長した分だけカメラの前方方向に移動する。Ｃ６では、以上説明したサイクルが繰り返されて、レンズ枠は、Ｃ４と比べ、上部駆動シャフト用圧電素子の伸長分だけカメラの前方方向に移動する。
【０１００】
ここで、レンズ枠をカメラ前方方向ではなくカメラ背面方向に移動させる場合については（ｄ）に示されている。
【０１０１】
（ｄ）には、上部および下部駆動シャフト用圧電素子の伸縮については同じであるものの、それら駆動シャフトそれぞれに対する上部圧電素子および下部圧電素子の結合状態が（ｃ）とは逆になっている。
【０１０２】
図１４は、表１の（ｄ）に示されるように圧電素子が動作した場合のレンズ枠の駆動の様子を示す図である。
【０１０３】
図１４には、レンズ枠が図１３とは逆にカメラ背面方向に移動されている様子が示されている。尚、（ｄ）および図１４についての説明は、（ｃ）および図１３についてした説明と基本的に同じとなるので省略する。
【０１０４】
この第２実施形態の（ｃ）および（ｄ）に示される態様では、２本の駆動シャフトを互いに逆方向に移動させるとともに、これら駆動シャフトに対するレンズ枠の結合状態を上部と下部で逆の状態にすることで、（ａ）および（ｂ）においてはレンズ枠の移動を行うことができなかったタイミングにおいてもレンズ枠を移動させることができるため、第１実施形態よりも高速にレンズ枠の移動を行うことが可能である。
【０１０５】
図１５は、本実施形態の（ｃ）および（ｄ）に示される態様が採用されているカメラにおいて、予備撮影が行われた後に起動されるルーチンのフローチャートである。
【０１０６】
図１５に示されるステップＳ１では、レンズ枠の移動方向がカメラ前方方向であるか否かが判定される。
【０１０７】
ステップＳ１において移動方向がカメラ前方であると判定されると、ステップＳ２に進み、上部圧電素子は固定状態に、下部圧電素子は非駆動状態にされ、ステップＳ３では、上部駆動シャフト用圧電素子が伸長され、下部駆動シャフト用圧電素子が短縮される。その後、ステップＳ４において、レンズ枠が目標位置に到達したか否かが判定され、到達したと判定されるとステップＳ１４に進み、到達していないと判定されるとステップＳ５に進む。
【０１０８】
ステップＳ５では、上部圧電素子は非駆動状態に、下部圧電素子は固定状態にされ、ステップＳ６では、上部駆動シャフト用圧電素子が短縮され、下部駆動シャフト用圧電素子が伸長される。その後、ステップＳ７に進み、レンズ枠が目標位置に到達したか否かが判定され、到達した判定されるとステップＳ１４に進み、到達していないと判定されると、ステップＳ１に戻る。
【０１０９】
一方、ステップＳ１において、レンズ枠の移動方向がカメラ前方方向ではなく、カメラ背面方向であると判定されると、ステップＳ８に進み、上部圧電素子は非駆動状態に、下部圧電素子は固定状態にされ、ステップＳ９では、上部駆動シャフト用圧電素子が伸長され、下部駆動シャフト用圧電素子が短縮される。その後、ステップＳ１０では、レンズ枠が目標位置に到達したか否かが判定され、到達したと判定されるとステップＳ１４に進み、到達していないと判定されるとステップＳ１１に進む。
【０１１０】
ステップＳ１１では、上部圧電素子は固定状態に、下部圧電素子は非駆動状態にされ、ステップＳ１２では、上部駆動シャフト用圧電素子が短縮され、下部駆動シャフト用圧電素子が伸長される。その後、ステップＳ１３に進み、目標位置に到達したか否かが判定され、到達したと判定されるとステップＳ１４に進み、到達していないと判定されるとステップＳ１に戻る。
【０１１１】
ステップＳ１４では、上部圧電素子および下部圧電素子が共に非駆動状態にされ、その後、このルーチンは終了される。
【０１１２】
以上に説明した第２実施形態であるレンズ駆動装置３００においても、レンズ枠の移動時には、駆動シャフトとレンズ枠とが互いに接触する部分に運動摩擦力はほとんど発生しないため、レンズ枠と駆動ロッドとが互いに接触する部分の摩擦係数の経年変化を抑制することができる。また、この第２実施形態では、１つのレンズ枠を光軸方向に移動させる例を挙げて説明したが、これに限らず、複数のレンズ枠それぞれが駆動シャフトに対し、ほとんど離間状態である非駆動状態と固定された固定状態との間で切替可能なクラッチ機構を備えているものであれば複数のレンズ群を有するものであってよい。
【０１１３】
尚、第１および第２実施形態では、駆動シャフト用圧電素子への印加電圧の電圧波形は、駆動方向によらず一定であり、駆動方向は、レンズ枠用圧電素子への印加タイミングによって決まる。その印加電圧も２値などの不連続でかまわないため、従来のように連続的に電圧値を変化させなければならない場合と比べ回路を単純にすることができる。また、デジタルカメラに採用された場合を例に挙げて説明したが、これに限らず、ロール状の写真フィルムに写真撮影を行なう通常のカメラ、あるいはビデオカメラに採用されるものであってよく、また、駆動シャフトに対するレンズ保持枠の結合状態を切り替えるクラッチ機構に圧電素子が採用されている例を挙げて説明したが、これに限らず、レンズ保持枠に電磁石を備え、この電磁石により引きつけたものによって駆動シャフトに対する摩擦力を制御するものであってよく、あるいは、その電磁石の磁力によって駆動シャフトとの結合状態を制御するものであってもよい。
【０１１４】
【発明の効果】
以上説明したように、本発明のレンズ駆動装置によれば、レンズ保持枠と駆動ロッドとが互いに接触する部分の摩擦係数の経年変化が抑制することができる。
【図面の簡単な説明】
【図１】本発明のレンズ駆動装置の第１実施形態を採用するカメラの正面図である。
【図２】図１に示されるカメラの背面図である。
【図３】図１および図２に示されるカメラの内部構成図である。
【図４】カメラの前方側から第１駆動部を見た場合を示す図である。
【図５】カメラ前方側への駆動原理を示す図である。
【図６】駆動シャフト用圧電素子に印加する電圧の変化を示す図である。
【図７】カメラ背面側への駆動原理を示す図である。
【図８】駆動部をカメラ背面側に移動させる場合の、駆動シャフト用圧電素子に印加される電圧の変化を表すグラフ図である。
【図９】駆動シャフト用圧電素子に対する印加電圧の一例を示す図である。
【図１０】予備撮影が終了すると起動されるルーチンのフローチャートである。
【図１１】本発明のレンズ駆動装置の第２実施形態の一部を示す図である。
【図１２】カメラの前方側から図７に示されるレンズ駆動部を見た場合を示す図である。
【図１３】表１の（ｃ）に示される態様によるレンズ枠の移動の様子を示す図である。
【図１４】表１の（ｄ）に示されるように圧電素子が動作した場合のレンズ枠の移動の様子を示す図である。
【図１５】本実施形態において（ｃ）および（ｄ）に示される態様が採用されているカメラにおいて、予備撮影が行われた後に起動されるルーチンのフローチャートである。
【符号の説明】
１ カメラ
１０ 後面レンズ
１１ 前面レンズ
１２ レンズ鏡胴
１３ａ ファインダ対物窓
１３ｂ ファインダ接眼窓
１４ レリーズボタン
１５ フラッシュ発光窓
１６ マイクロフォン
１７ａ 機能スイッチ
１７ｂ モードスイッチ
１８ 液晶パネル
１９ ズームスイッチ
２０ スピーカ
１００、３００ レンズ駆動装置
１１０ 第１駆動部
１１１ ズームレンズ保持枠
１１１ａ 凹部
１１１ｂ 可動部
１１２ 第１圧電素子
１１２ａ 第１圧電素子ドライバ
１１３ ズームレンズ
１２０ 第２駆動部
１２１ フォーカスレンズ保持枠
１２１ａ 凹部
１２１ｂ 可動部
１２２ 第２圧電素子
１２２ａ 第２圧電素子ドライバ
１２３ フォーカスレンズ
１３０ 駆動シャフト用圧電素子
１３０ａ 駆動シャフト用圧電素子ドライバ
１４０ 駆動シャフト
１５０ 案内シャフト
２１０ ＣＣＤ撮像素子
２１１ Ａ／Ｄ変換回路
２１２ 画像信号処理回路
２１３ バッファメモリ
２１４ 画像入力コントローラ
２１５ ＡＦ／ＡＥ演算回路
２１６ ＣＰＵ
２１７ バス
２１８ メモリ
２１９ キーコントローラ
２２０ 圧縮処理回路
２２１ メディアコントローラ
２２２ 画像表示制御回路
２２３ 外部記憶装置
３１０ 駆動部
３１１ レンズ保持枠
３１２ 上部圧電素子
３１１２ａ、３１１３ａ 凹部
３１１２ｂ、３１１３ｂ 可動部
３１２ａ 上部圧電素子ドライバ
３１３ 下部圧電素子
３１３ａ 下部圧電素子ドライバ
３１４ レンズ群
３２０ 下部駆動シャフト
３３０ 下部駆動シャフト用圧電素子
３４０ 上部駆動シャフト
３５０ 上部駆動シャフト用圧電素子[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lens driving device that employs an electro-mechanical conversion element for moving a lens group.
[0002]
[Prior art]
Conventionally, in a camera or video camera equipped with an autofocus function and a power zoom function, distance information indicating the distance to the subject, contrast information of the subject image formed on the solid-state image sensor, and an operation amount with respect to the zoom lever Based on this, the focus lens and zoom lens are moved to the target position on the optical axis.
[0003]
Among these, the movement of the focus lens and the zoom lens in the optical axis direction is performed by rotating a lead screw screwed into a screw hole provided in a lens holding frame for holding each of these lenses with a separate motor. There is something to do.
[0004]
However, the lens driving device using a motor as described above has a problem that the structure is complicated and it is difficult to reduce the size.
[0005]
Japanese Patent Application Laid-Open No. 9-191676 discloses a lens driving device in which an electro-mechanical conversion element that expands and contracts in a predetermined direction according to a change in applied voltage is applied to each of a focus lens and a zoom lens. Proposed in the gazette.
[0006]
In the lens driving device proposed in the above publication, the lens holding frame that holds the focus lens and the zoom lens is a driving rod that reciprocates in the optical axis direction along with the electromechanical conversion element that expands and contracts in the optical axis direction. Are coupled with a predetermined friction force. Therefore, in this lens driving device, these lens holding frames are moved relative to the driving rod only when the driving rod is operated with an acceleration of a predetermined level or more that causes an inertial force exceeding the predetermined frictional force. Thus, the focus lens and the zoom lens are moved in the optical axis direction.
[0007]
[Problems to be solved by the invention]
However, when the lens holding frame is moved by operating the driving rod with a predetermined acceleration or more, a kinetic frictional force is generated at the contact portion between each lens holding frame and the driving rod. The contact surface with the drive rod and the surface of the drive rod are stressed, and the friction coefficient of the portion may change over time.
[0008]
For example, when the friction coefficient increases due to this stress, there arises a problem that in order to move the lens frame, the electromechanical conversion element has to be expanded and contracted so that the drive rod operates at a higher acceleration.
[0009]
In view of the above circumstances, the present invention adopts an electro-mechanical conversion element for moving the lens group in the optical axis direction, in which the secular change of the friction coefficient of the portion where each lens holding frame and the drive rod contact each other is suppressed. It is an object of the present invention to provide a lens driving device.
[0010]
[Means for Solving the Problems]
  To achieve the above object, the present inventionThe first of the lens driving devicesThe lens driving device
  Extends in the optical axis directionsingleA drive rod;
  While holding the lens groupInserted in the drive rod, The coupling state with the drive rod,Each independentlyProvided with a clutch mechanism that can be switched between a fixed state fixed to the drive rod and a non-drive state that avoids driving by the drive rod.pluralA lens holding frame;
  The drive rod is reciprocated in the extending direction of the drive rod.With electro-mechanical transducer,
  In cooperation with the operation of the clutch mechanism,pluralThe lens holding frameSelectivelyMove along the optical axisOr stopMakeConfigured asIt is characterized by that.
[0011]
In the lens driving device of the present invention, with the above-described configuration, the lens holding frame is coupled to the driving rod in a fixed state in which the lens holding frame is fixed to the driving rod and a non-driving state in which the driving rod is almost separated from the driving rod. Can be switched between. In other words, in the conventional case where the lens frame is coupled to the drive rod with a predetermined frictional force, a kinetic frictional force is generated between the lens frame and the drive rod. In the lens driving device of the present invention, the movement of the lens holding frame with respect to the driving rod is performed with little contact with the driving rod, so that little kinetic frictional force is generated. Thereby, the stress to the contact surface with the drive rod of each lens holding frame and the surface of the drive rod can be reduced. Therefore, according to the lens driving device of the present invention, it is possible to suppress the secular change of the friction coefficient of the portion where the lens holding frame and the driving rod are in contact with each other.
[0012]
In order to achieve the above object, a second lens driving device of the lens driving device of the present invention includes two driving rods extending in the optical axis direction,
The lens group is held, and is inserted into the drive rod, and the coupling state with the drive rod is divided into a fixed state that is independently fixed to the drive rod and a non-drive state that avoids driving by the drive rod. A plurality of lens holding frames with a clutch mechanism that can be switched between;
An electro-mechanical conversion element for reciprocating the drive rod in the extending direction of the drive rod;
The plurality of lens holding frames are configured to move in different directions along the optical axis in cooperation with the operation of the clutch mechanism..
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0014]
FIG. 1 is a front view of a camera that employs a first embodiment of the lens driving device of the present invention.
[0015]
The camera 1 is a digital camera equipped with a lens barrel and having an autofocus and power zoom function. However, the length of the lens barrel is unchanged even during focusing and zooming.
[0016]
On the front surface of the camera 1 shown in FIG. 1, a lens barrel 12 containing a front lens 11 is near the center, a flash emission window 15 is above the lens barrel 12, and a finder objective window 13 a is the flash emission window 15. On the left (right in FIG. 1), a microphone 16 is provided between the finder objective window 13a and the lens barrel 12, and a release button 14 is provided on the upper right end (upper left end in FIG. 1).
[0017]
FIG. 2 is a rear view of the camera shown in FIG.
[0018]
On the back side of the camera 1 shown in FIG. 2, the liquid crystal panel 18 is slightly near the center, the speaker 20 is on the right side of the liquid crystal panel, the zoom switch 19 is above the speaker 20, the function switch 17a and the shooting mode switch 17b. Above the liquid crystal panel 18, a viewfinder eyepiece window 13b is provided at the upper left corner.
[0019]
The camera 1 has two functions of a “photographing and recording” function and an “image data reproduction” function, and one of the functions is selected by the function switch 17a. Furthermore, the 'shooting and recording' function includes a 'portrait shooting' mode, a 'sport shooting' mode, and a 'landscape shooting' mode, and any one of these modes is selected by the shooting mode switch 17b. The zoom switch 19 is zoomed to the telephoto side by operating the upward triangular portion, and is zoomed to the wide angle side by operating the downward triangular portion.
[0020]
FIG. 3 is an internal configuration diagram of the camera shown in FIGS. 1 and 2.
[0021]
FIG. 3 shows a lens driving mechanism 100 according to the present embodiment. The lens driving mechanism 100 is joined to a driving shaft piezoelectric element 130 that expands and contracts in a predetermined direction and the driving shaft piezoelectric element 130. A drive shaft 140, a drive shaft piezoelectric element driver 130a, a first drive unit 110 including a zoom lens group located on the left side in the lens barrel shown in FIG. 1, and a focus lens on the right side of the first drive unit The second drive unit 120 includes a group, and a guide shaft 150 that assists the stable movement of the first and second drive units in the lens barrel.
[0022]
The first drive unit 110 further includes a zoom lens holding frame 111, a zoom lens group 113, a first piezoelectric element 112, and a first piezoelectric element driver 112a, and the second drive unit 120 includes a focus lens. The lens holding frame 121, the focus lens group 123, a second piezoelectric element 122, and a second piezoelectric element driver 122a are included.
[0023]
FIG. 3 shows a state in which the guide shaft 150 is fixed above the inside of the lens barrel and one end of the drive shaft piezoelectric element 130 is fixed below the inside of the lens barrel. The drive shaft piezoelectric element 130 expands and contracts in the optical axis direction of the camera, that is, in the left direction in FIG.
[0024]
In the lens barrel shown in FIG. 3, a zoom lens holding frame 111 that is a component of the first drive unit 110 and a focus lens holding frame 121 that is a component of the second drive unit 120 sandwich the drive shaft 140. On the other hand, a state of being penetrated by the guide shaft 150 is shown.
[0025]
Further, the front lens 11 shown in FIG. 1 is fitted on the front side of the lens barrel 12 shown in FIG. 3, and the rear lens 10 is provided on the rear side of the lens barrel shown in FIG. It is inserted.
[0026]
FIG. 4 is a diagram illustrating a case where the first drive unit is viewed from the front side of the camera.
[0027]
FIG. 4 shows a zoom lens holding frame 111 that holds the zoom lens group 113 so as to surround the zoom lens group 113, and shows that the zoom lens holding frame 111 further has a movable portion 111b. In the zoom lens holding frame 111, a concave portion 111a for sandwiching the drive shaft 140 is formed by the movable portion 111b and other portions excluding the movable portion 111b. In FIG. The first piezoelectric element 112 is arranged so as to expand and contract in the vertical direction of the zoom lens holding frame 111, and the drive shaft 140 is sandwiched. Note that the above description is the same for the second drive unit 120, and although not shown, the focus lens holding frame 121 of the second drive unit also includes the movable unit 121b and other parts excluding the movable unit 121b. Thus, a recess 121a for sandwiching the drive shaft 140 is formed. As described above, in the lens driving mechanism 100, the coupling to the driving shaft 140 is determined by the expansion and contraction of the first piezoelectric element 112 of the first driving unit 110 and the second piezoelectric element 122 of the second driving unit 120.
[0028]
3 further shows a CCD image pickup device 210 provided on the right side of the lens barrel 12, an A / D conversion circuit 211 that converts an analog image signal obtained from the image pickup device into a digital signal, and this camera. 1, a CPU 216 that controls the whole, a buffer memory 213 that is also used as a work area, an image input controller 214 that stores digital image data in the buffer memory 213, and a digital image data stored in the buffer memory so that it can be compressed An image signal processing circuit 212 for processing, a compression processing circuit 220 for compressing digital image data processed to be compressible, and a media controller 221 for recording the compressed digital image data converted into a file format by the CPU 216 in the external storage device 223. , Transferred from the buffer memory 213 A memory 218 for storing the uncompressed digital image data, a video signal is created by adding a synchronization signal to the uncompressed digital image data stored in the memory 218, and the video signal is converted from a digital signal to an analog signal. Also shown is an image display control circuit 222 that amplifies. An image is displayed on the liquid crystal panel 18 by the control of the image display control circuit 222.
[0029]
FIG. 3 also shows an AF / AE arithmetic circuit 215 that detects contrast information and luminance information from an image based on an image signal output from the CCD image sensor 210, a zoom switch 19, a function switch 17a, and a shooting mode switch. 17b, a release switch 14, a key controller 219 for detecting an operation on these switches, and a bus 217 to which the circuits described above are connected.
[0030]
Here, focusing and zooming operations in photographing with the camera 1 will be described.
[0031]
In this camera 1, when a main switch (not shown) is turned on and “shooting recording” is selected by the function switch 17a, preliminary shooting before the main shooting is performed.
[0032]
In the preliminary photographing, the image signal output from the CCD image pickup device 210 is sent to the A / D conversion circuit 211 and converted into a digital signal, and then sent to the image input controller 214, and the AF / AE is sent from the image input controller 214. It is sent to the arithmetic circuit.
[0033]
The AF / AE calculation circuit 215 measures the contrast of the image signal and calculates distance measurement information up to the subject. This distance measurement information is sent to the CPU 31. The AF / AE arithmetic circuit 215 assumes digital processing, but the AF / AE arithmetic circuit 215 may process an analog signal.
[0034]
On the other hand, the zoom level set by the zoom switch 19 is also sent to the CPU 31.
[0035]
In this way, the CPU 31 calculates the in-focus position from the sent distance measurement information and the focal length from the zoom level.
[0036]
In this camera 1, the drive shaft piezoelectric element driver 130a, the first piezoelectric element driver 122a, and the second piezoelectric element driver 112a are controlled by the CPU 216, and the CPU 216 corresponds to the calculated in-focus position and focal length. The driver is instructed so that the zoom lens group and the focus lens group are arranged at the positions. Thereafter, the actual photographing is performed after the lens groups are moved to the target position.
[0037]
Here, a piezoelectric element that is an electro-mechanical conversion element will be described.
[0038]
The piezoelectric element expands in a predetermined direction as the voltage increases, and the degree of expansion is proportional to the degree of increase in voltage. When the voltage starts to decrease, the piezoelectric element starts to decrease. It is proportional to the degree. Accordingly, when the voltage is slowly increased or decreased, the piezoelectric element slowly expands or shortens, and when the voltage is rapidly increased or decreased, the piezoelectric element rapidly expands or shortens.
[0039]
Furthermore, a conventional lens movement using the piezoelectric element will be briefly described.
[0040]
First, the case where the drive part 110 is moved to the camera front side is demonstrated. In the following, the principle proposed in Japanese Patent Laid-Open No. 9-191676 will be described.
[0041]
FIG. 5 is a diagram illustrating the principle of driving the camera forward.
[0042]
FIG. 6 is a diagram showing a change in voltage applied to the drive shaft piezoelectric element in this case.
[0043]
FIG. 6 shows a change in the applied voltage that gradually increases and rapidly decreases after a predetermined voltage is reached.
[0044]
When a voltage that changes as shown in FIG. 6 is applied to the drive shaft piezoelectric element 130, the thickness of the drive shaft piezoelectric element 130 from the state shown in FIG. The thickness gradually increases and the state shown in FIG. For this reason, the drive shaft 140 is pushed by the piezoelectric element 130 and moves in the forward direction of the camera (left side in FIG. 5). Then, as shown in FIG. 5B, the drive unit 110 placed in a driven state with respect to the drive shaft moves the drive shaft 140 in the forward direction of the camera (the left direction in FIG. 5) at a considerably slow speed. Therefore, it moves in the forward direction of the camera without slipping with respect to the drive shaft 140.
[0045]
However, after this applied voltage reaches the value V1, it suddenly decreases to a value of 0 after a while, so that the thickness of the piezoelectric element 130 is rapidly reduced. Then, the drive shaft 140 also moves rightward in FIG. 5 as shown in FIG. Due to this sudden movement of the drive shaft 140, the drive unit 110 remains at the position shown in FIG. 5B before the drive shaft 140 moves suddenly. This means that the camera has advanced in the front direction of the camera by the indicated distance x.
[0046]
Next, the case where this drive part 110 is moved to the camera back side is demonstrated.
[0047]
FIG. 7 is a diagram showing the principle of driving to the rear side of the camera.
[0048]
In this case, the applied voltage to the drive shaft piezoelectric element 130 may have a change as shown in FIG.
[0049]
FIG. 8 is a graph showing a change in voltage applied to the drive shaft piezoelectric element when the drive unit is moved to the back side of the camera.
[0050]
FIG. 8 shows a state in which the applied voltage increases rapidly and then decreases gently.
[0051]
In this case, the piezoelectric element 130 in the state shown in FIG. 7 (a) is supplied with the suddenly rising drive voltage shown in FIG. 7, and suddenly moves in the forward direction of the camera (left side in FIG. 7). Elongate. As a result, the drive shaft 140 also suddenly moves in the forward direction of the camera, so that the drive unit 110 slides on the drive shaft 140 in the rear direction of the camera as shown in FIG. 7B. After that, as shown in FIG. 7C, the piezoelectric element 130 is gradually contracted in the rear direction of the camera (right side in FIG. 7) due to the supply of the driving voltage that gradually decreases. Move in the direction. Since the operation of the drive shaft 140 is slow, the drive unit 110 also moves to the rear side of the camera together with the drive shaft without sliding with respect to the drive shaft. As a result, the drive unit 110 has moved by the distance Y toward the back side of the camera.
[0052]
In this embodiment, when receiving an instruction from the CPU 216, the drive shaft piezoelectric element driver 130a changes the supply voltage to the drive shaft piezoelectric element 130 to control the speed of expansion and contraction. In addition, the first and second piezoelectric element drivers 112a and 122a also receive instructions from the CPU 216 and change the supply voltage to the first and second piezoelectric elements, so that the first and second piezoelectric elements 112 and 122 expand and contract. And the coupling state of the lens holding frame with respect to the drive shaft is set to one of a non-drive state in a substantially separated state and a fixed state in which the lens is fixed.
[0053]
The right end surface of the drive shaft piezoelectric element 130 shown in FIG. 3 is fixed in the lens barrel, so that when the voltage increases, it expands in the forward direction of the camera, and when the voltage decreases, it shortens in the rear direction of the camera. To do. Along with this, the drive shaft 140 reciprocates in the optical axis direction of the camera 1.
[0054]
In addition, how to move the first and second driving units will be briefly described below.
[0055]
First, a case will be described in which only the first drive unit including the zoom lens group is moved to the front side of the camera, and the second drive unit including the focus lens group is left at the same position.
[0056]
In this case, first, the expansion and contraction of the first and second piezoelectric elements is controlled so that the contact state of the zoom lens frame 111 and the focus lens frame 121 with respect to the drive shaft 140 is fixed.
[0057]
FIG. 9 is a diagram illustrating an example of a voltage applied to the drive shaft piezoelectric element.
[0058]
FIG. 9 shows the state of change in applied voltage that rapidly increases and enters a constant voltage state for a while when it reaches a predetermined voltage (V1) and then decreases rapidly. The lens frame with respect to the drive shaft is in a substantially separated state in the non-drive state, but is not completely in a float state due to its own weight, etc., so the drive shaft moves with a steep operation. Is done.
[0059]
When a voltage changing as shown in FIG. 9 is applied to the drive shaft piezoelectric element 130, the drive shaft rapidly moves in the forward direction of the camera in a portion where the voltage suddenly increases. On the other hand, the zoom lens frame 111 and the focus lens frame 121 placed in a fixed state move in the forward direction of the camera along with the rapidly moving drive shaft 140. Thereafter, when the applied voltage reaches the value V1, the constant voltage state is reached. While the applied voltage is in a constant voltage state, that is, while the drive shaft is moved and stopped at a predetermined position in the lens barrel, only the coupled state of the zoom lens frame 111 to the drive shaft 140 is not driven from the fixed state. Switch to state. Thereby, the zoom lens frame 111 is almost separated from the drive shaft. Thereafter, when the applied voltage suddenly decreases, the drive shaft 140 moves in the back direction of the camera. The zoom lens frame 111 that is substantially separated from the drive shaft 140 due to the rapid movement of the drive shaft 140 in the rear direction of the camera is located before the drive shaft 140 is moved in the rear direction. As a result, only the zoom lens frame 111 is moved in front of the camera.
[0060]
Assuming that the drive shaft 140 is moved back and stops again, the coupling state of the zoom lens frame 111 is switched from the non-driving state to the fixed state, and the above is repeated, so that only the zoom lens is left without changing the focus lens. It can be moved further forward.
[0061]
Next, a case where only the first drive unit is moved to the rear side of the camera and the second drive unit is left at the same position will be described.
[0062]
In this case, with respect to the drive shaft 140, the zoom lens frame 111 is in a non-driven state and the focus lens frame 121 is in a fixed state, and a voltage having a change shown in FIG. Due to the rapid movement of the drive shaft 140 in the forward direction of the camera due to the rapid rise of the applied voltage, the zoom lens frame 111 that is substantially separated from the drive shaft 140 is moved before the drive shaft 140 is moved in the forward direction. Thus, only the zoom lens frame 111 can be moved to the base side of the drive shaft 140. Thereafter, the coupling state of the zoom lens frame 111 is switched from the non-driving state to the fixed state in anticipation of when the applied voltage becomes a constant voltage state and the driving shaft 140 stops. Thereafter, when a rapidly decreasing voltage is applied and the drive shaft 140 is moved in the back direction of the camera, only the zoom lens is moved to the back side of the camera without changing the focus lens. Assuming that the drive shaft 140 is moved back and stopped again, the zoom lens frame 111 is switched from the fixed state to the non-driven state by repeating the above, and the focus lens remains as it is and only the zoom lens is switched to the camera. It can be moved further in the back direction.
[0063]
Further, the case where only the second drive unit including the focus lens group is moved to the front side or the back side of the camera and the first drive unit is left at the same position can be performed in the same way as described above. Is omitted. In this embodiment, it is only necessary to apply a voltage that changes to a pulse wave shape as shown in FIG. 9, so the control circuit that controls this voltage controls the applied voltage as shown in FIG. 6 or FIG. Compared to the case, a simple circuit can be used. The confirmation of the zoom lens and the focus lens reaching the target position is monitored by an encoder (not shown) attached to each lens frame and inside the lens barrel.
[0064]
FIG. 10 is a flowchart of a routine that is started when the preliminary shooting is completed.
[0065]
In step S1 shown in FIG. 10, it is determined whether or not the first drive unit 110 including the zoom lens group is to be moved.
[0066]
If it is determined in step S1 that the zoom lens group is to be moved, the process proceeds to step S2, and it is determined whether or not the direction of the movement is the front direction of the camera.
[0067]
If it is determined in step S2 that the direction of movement is the front direction of the camera, the process proceeds to step S3, and both the zoom lens frame and the focus lens frame are fixed to the drive shaft. Thereafter, in step S4, a rapidly increasing voltage shown in FIG. 9 is applied to the drive shaft piezoelectric element. As a result, the drive shaft suddenly moves to the front side of the camera. Thereafter, when the applied voltage becomes a constant voltage, the drive shaft stops while moving to the front side of the camera, and in step S5, the coupling state of the zoom lens frame to the drive shaft is switched from the fixed state to the non-driven state. Thereafter, in step S6, the voltage that rapidly decreases as shown in FIG. 9 is applied to the drive shaft piezoelectric element, whereby the drive shaft piezoelectric element is rapidly shortened, resulting in the zoom lens frame being a camera. Move forward. Then, it progresses to step S11.
[0068]
On the other hand, if it is determined in step S2 that the moving direction is not the front direction of the camera, the moving direction is the back direction of the camera, and only the focus lens frame is fixed in step S7. In step S8, the rapidly increasing voltage shown in FIG. 9 is applied to the drive shaft piezoelectric element, whereby the drive shaft is suddenly moved in the forward direction of the camera, so that the zoom lens frame is located on the root side of the drive shaft. Move to. Thereafter, when the applied voltage becomes a constant voltage, the drive shaft stops while moving to the back side of the camera, and in step S9, the coupled state of the zoom lens frame to the drive shaft is switched from the non-driven state to the fixed state. Thereafter, in step S10, a voltage that rapidly decreases as shown in FIG. 9 is applied to the drive shaft piezoelectric element, whereby the drive shaft piezoelectric element is rapidly shortened. As a result, the zoom lens frame is Move to the back of the camera. Then, it progresses to step S11.
[0069]
In step S11, it is determined whether or not the zoom lens frame has reached the target position. If it is determined that the zoom lens frame has not yet reached the target position, the process returns to step S2, and if it is determined that the target position has been reached, step S22 is performed. Proceed to
[0070]
Here, when it is determined in step S1 that the movement is not with respect to the zoom lens frame but with respect to the focus lens frame, the description will be returned. In this case, the process proceeds to step S12, and it is determined whether or not the direction of movement is the front direction of the camera. If it is determined in step S12 that the movement is in the forward direction of the camera, the process proceeds to step S13, and the zoom lens frame and the focus lens frame are both fixed to the drive shaft. Thereafter, in step S14, the rapidly increasing voltage shown in FIG. 9 is applied to the drive shaft piezoelectric element. As a result, the piezoelectric element for the drive shaft is rapidly expanded, and the drive shaft is also rapidly moved to the front side of the camera. Thereafter, when the applied voltage becomes a constant voltage, the drive shaft stops while moving to the front side of the camera, and in step S15, the coupling state of the focus lens frame to the drive shaft is switched from the fixed state to the non-driven state. Thereafter, in step S16, the voltage that rapidly decreases as shown in FIG. 9 is applied to the drive shaft piezoelectric element, whereby the drive shaft piezoelectric element is rapidly shortened, and the focus lens frame is Move to the front of the camera. Then, it progresses to step S21.
[0071]
On the other hand, if it is determined in step S12 that the movement is in the rear direction of the camera, the process proceeds to step S17, where only the zoom lens frame is changed from the non-driven state to the fixed state, and in step S18, the piezoelectric element for the drive shaft increases rapidly. Voltage is applied. Thereafter, in step S19, the coupled state of the focus lens frame is changed from the non-driven state to the fixed state. In step S20, a voltage that rapidly decreases is applied to the drive shaft piezoelectric element. As a result, the focus lens frame eventually moves in the rear direction of the camera. Then, it progresses to step S21.
[0072]
In step S21, it is determined whether or not the focus lens frame has reached the target position. If it is determined that the focus lens frame has not yet reached the target position, the process returns to step S12 to determine that the focus lens frame has reached the target position. Then, it progresses to step S22.
[0073]
In step S22, the state of the zoom lens frame and the focus lens frame with respect to the drive rod is changed from the fixed state to the non-driven state. Thereafter, the process proceeds to step S23, where it is determined whether both the zoom lens frame and the focus lens frame have reached the target position. If it is determined in step S23 that both have not reached the target position, the process returns to step S1, and if it is determined that both have reached the target position, this routine is terminated.
[0074]
In the lens driving device according to the first embodiment described above, the non-driving state, which is a coupling state with respect to the driving rod when the lens frame is moved, is almost separated from the driving rod. When the frame moves on the drive rod, the kinetic frictional force of the portion where the drive rod and the lens frame are in contact with each other is reduced. Therefore, according to the lens driving device of the present embodiment, it is possible to suppress the secular change of the friction coefficient at the portion where the lens holding frame and the driving rod are in contact with each other.
[0075]
Hereinafter, a second embodiment of the lens driving device of the present invention will be described. The second embodiment will also be described as being used in the same type of camera as that shown in FIGS.
[0076]
FIG. 11 is a diagram showing a part of a second embodiment of the lens driving device of the present invention.
[0077]
FIG. 11 shows a part of the lens driving device 300 of the present embodiment, and the same reference numerals as those in FIG. 3 are assigned to the same types as those shown in FIG. Has been.
[0078]
A lens driving device 300 shown in FIG. 11 includes an upper drive shaft piezoelectric element 350 that is fixed inside the lens barrel 12 shown in FIG. 3 and expands and contracts in a predetermined direction, and the upper drive shaft piezoelectric element. 350, the upper drive shaft 340, the upper drive shaft piezoelectric element driver 350a, the lower drive shaft piezoelectric element 330 that is fixed below the lens barrel 12 and expands and contracts in a predetermined direction, and the lower drive shaft. It comprises a piezoelectric element driver 330a, a lower drive shaft 320 joined to the lower drive shaft piezoelectric element 330, and a drive unit 310 including a lens group.
[0079]
Further, the drive unit 310 includes a lens holding frame 311, a lens group 314, an upper piezoelectric element 312, an upper piezoelectric element driver 312 a, a lower piezoelectric element 313, and a lower piezoelectric element driver 313 a. The driver for controlling the expansion and contraction of the upper drive shaft piezoelectric element 350, the lower drive shaft piezoelectric element 330, the upper piezoelectric element 312 and the lower piezoelectric element 313 is not shown, and is actually provided. The guide shaft is not shown for guiding the lens driving unit 310.
[0080]
The ends of the upper drive shaft piezoelectric element 350 and the lower drive shaft piezoelectric element 330 shown in FIG. 11 are fixed above and below the lens barrel, respectively. Thus, the upper and lower drive shaft piezoelectric elements expand and contract in the optical axis direction of the camera.
[0081]
In the lens barrel shown in FIG. 11, the lens holding frame 311 shows the upper and lower drive shafts sandwiched between them.
[0082]
Further, the front lens 11 shown in FIG. 1 is fitted on the front side of the lens barrel shown in FIG. 11, and the rear lens 10 is fitted on the rear side of the lens barrel shown in FIG. It is.
[0083]
12 is a diagram illustrating a case where the lens driving unit illustrated in FIG. 11 is viewed from the front side of the camera.
[0084]
FIG. 12 shows a lens holding frame 311 that holds the lens group 314 so as to surround the lens group 314. The lens holding frame 311 has movable portions 3112b and 3113b at two upper and lower positions. Yes. The lens holding frame 311 is formed with recesses 3112a and 3113a for sandwiching the upper and lower drive shafts 340 and 320 by the movable portions 3112b and 3113b and other portions excluding these movable portions. 12, the upper piezoelectric element 312 and the lower piezoelectric element 313 are disposed in the recesses 3112a and 3113a so as to expand and contract in the vertical direction of the lens holding frame, and the upper drive shaft 340 and the lower drive shaft 320 are sandwiched therebetween. The situation is shown. In this lens driving mechanism 300, the coupling state with respect to the upper driving shaft 340 and the lower driving shaft 320 is determined by expansion and contraction of the upper piezoelectric element 312 and the lower piezoelectric element 313. As in the first embodiment, the coupled state is either a fixed state that is fixed to the drive rod or a non-driven state that is almost separated from the drive shaft.
[0085]
Here, the movement of the lens group in the present embodiment will be described.
[0086]
In the lens driving device 300 of the present embodiment, the lens group can be moved in the following three modes.
[0087]
[Table 1]

[0088]
(A) to (d) of Table 1 show three aspects in the present embodiment, respectively, and (a) shows an aspect in which the lens frame is moved in the same procedure as in the first embodiment. (B) shows a mode in which the lens frame can be moved even under a high load with respect to the first embodiment, and (c) and (d) show a movement of the lens frame with respect to the first embodiment. The mode which can be performed at high speed is shown.
[0089]
(A) to (d) show the states of the upper drive shaft, the upper piezoelectric element, the lower drive shaft, the lower piezoelectric element, and the lens frame over time.
[0090]
First, a mode in which the lens frame is moved in the second embodiment shown in (a) by the same method as in the first embodiment will be described.
[0091]
In this aspect, the lower piezoelectric element of the upper and lower piezoelectric elements that switches the coupling state of the lens frame to the upper drive shaft is always in the non-driven state, so the lower shaft of the upper and lower drive shafts moves. do not do. Therefore, the mode shown in (a) has the same procedure and configuration as the first embodiment although the position of the driving shaft is upside down, and the description thereof will be omitted.
[0092]
Next, a mode in which the lens frame can be moved under a high load, although the movement procedure is the same as in the first embodiment shown in FIG.
[0093]
In this aspect, in the first embodiment, the switching of the coupling state of the lens frame to the drive shaft, which has been performed for one drive shaft provided below, is performed on each of the drive shafts provided above and below. On the other hand, at the same time and in the same procedure. Thereby, in this aspect, since the lens frame can be fixed to both the upper and lower drive shafts, the movement of the drive shaft in the lens barrel that is the basis of the movement is applied to the lens frame. It can be done against the load. Note that the description of the operation of this aspect is omitted because it overlaps with the description in FIG.
[0094]
Finally, a mode in which the lens frame can be moved at high speed with respect to the first embodiment shown in (c) will be described.
[0095]
In this aspect, as shown in (c), the piezoelectric element for the upper drive shaft and the piezoelectric element for the lower shaft operate in opposite directions to each other, and the upper piezoelectric element and the lower piezoelectric element are also coupled in the opposite directions. Coupled to each drive rod.
[0096]
FIG. 13 is a diagram showing the movement of the lens frame according to the mode shown in (c) of Table 1.
[0097]
In FIG. 13, the piezoelectric element for the upper drive shaft and the upper drive shaft, and the piezoelectric element for the lower drive shaft and the lower drive shaft are shown in four states (C1, C2, C4, and C6) in two upper and lower stages. The lens frame moves on the upper and lower drive shafts in the forward direction of the camera.
[0098]
Hereinafter, the aspect shown in (c) of Table 1 will be described with reference to FIG.
[0099]
First, in C1 shown below (c), the upper piezoelectric element is fixed to the upper drive shaft, and the lower piezoelectric element is not driven to the lower drive shaft. Then, at C2, the piezoelectric element for the upper drive shaft is extended, and conversely, the piezoelectric element for the lower drive shaft is shortened. The lens frame moves in the forward direction of the camera by an amount corresponding to the extension of the piezoelectric element for the upper drive shaft, as compared with C1. Next, while both drive shafts are stopped at C3, the upper piezoelectric element is changed from the fixed state to the upper drive shaft, and the lower piezoelectric element is fixed from the non-drive state to the lower drive shaft. To be. In this state, when the upper drive shaft piezoelectric element is shortened and the lower drive shaft piezoelectric element is expanded at C4 this time, the lens frame is in front of the camera by an amount corresponding to the extension of the lower drive shaft piezoelectric element compared to C2. Move in the direction. In C6, the cycle described above is repeated, and the lens frame moves in the forward direction of the camera by the extension of the piezoelectric element for the upper drive shaft, compared to C4.
[0100]
Here, the case where the lens frame is moved not in the front direction of the camera but in the rear direction of the camera is shown in (d).
[0101]
In (d), the expansion and contraction of the piezoelectric elements for the upper and lower drive shafts is the same, but the coupling state of the upper piezoelectric element and the lower piezoelectric element to each of these drive shafts is opposite to (c).
[0102]
FIG. 14 is a diagram showing how the lens frame is driven when the piezoelectric element is operated as shown in (d) of Table 1.
[0103]
FIG. 14 shows a state in which the lens frame is moved in the camera rear direction, contrary to FIG. The description of (d) and FIG. 14 is basically the same as the description of (c) and FIG.
[0104]
In the mode shown in (c) and (d) of the second embodiment, the two drive shafts are moved in opposite directions, and the coupling state of the lens frame to these drive shafts is reversed between the upper part and the lower part. Therefore, in (a) and (b), the lens frame can be moved even at a timing when the lens frame could not be moved, so that the lens frame can be moved faster than in the first embodiment. Can be done.
[0105]
FIG. 15 is a flowchart of a routine that is started after preliminary shooting is performed in a camera that adopts the modes shown in (c) and (d) of the present embodiment.
[0106]
In step S1 shown in FIG. 15, it is determined whether or not the moving direction of the lens frame is the front direction of the camera.
[0107]
If it is determined in step S1 that the moving direction is in front of the camera, the process proceeds to step S2, where the upper piezoelectric element is fixed and the lower piezoelectric element is not driven. In step S3, the upper drive shaft piezoelectric element is moved. The piezoelectric element for the lower drive shaft is shortened by being extended. Thereafter, in step S4, it is determined whether or not the lens frame has reached the target position. If it is determined that the lens frame has reached, the process proceeds to step S14. If it is determined that the lens frame has not reached, the process proceeds to step S5.
[0108]
In step S5, the upper piezoelectric element is set in a non-driven state and the lower piezoelectric element is set in a fixed state. In step S6, the upper drive shaft piezoelectric element is shortened and the lower drive shaft piezoelectric element is extended. Thereafter, the process proceeds to step S7, where it is determined whether or not the lens frame has reached the target position. If it is determined that the lens frame has reached, the process proceeds to step S14. If it is determined that the lens frame has not reached, the process returns to step S1.
[0109]
On the other hand, if it is determined in step S1 that the moving direction of the lens frame is not the camera front direction but the camera back direction, the process proceeds to step S8, where the upper piezoelectric element is in the non-driven state and the lower piezoelectric element is in the fixed state. In step S9, the piezoelectric element for the upper drive shaft is extended and the piezoelectric element for the lower drive shaft is shortened. Thereafter, in step S10, it is determined whether or not the lens frame has reached the target position. If it is determined that the lens frame has reached, the process proceeds to step S14. If it is determined that the lens frame has not reached, the process proceeds to step S11.
[0110]
In step S11, the upper piezoelectric element is fixed and the lower piezoelectric element is not driven. In step S12, the upper drive shaft piezoelectric element is shortened and the lower drive shaft piezoelectric element is extended. Thereafter, the process proceeds to step S13, where it is determined whether or not the target position has been reached. If it is determined that the target position has been reached, the process proceeds to step S14, and if it has not been reached, the process returns to step S1.
[0111]
In step S14, the upper piezoelectric element and the lower piezoelectric element are both brought into a non-driven state, and then this routine is ended.
[0112]
Also in the lens driving device 300 according to the second embodiment described above, when the lens frame is moved, the frictional force is hardly generated at the portion where the driving shaft and the lens frame are in contact with each other. It is possible to suppress the secular change of the coefficient of friction of the portions that are in contact with each other. In the second embodiment, an example in which one lens frame is moved in the optical axis direction has been described. However, the present invention is not limited to this, and each of the plurality of lens frames is almost separated from the drive shaft. As long as it has a clutch mechanism that can be switched between a driving state and a fixed state, it may have a plurality of lens groups.
[0113]
In the first and second embodiments, the voltage waveform of the voltage applied to the drive shaft piezoelectric element is constant regardless of the drive direction, and the drive direction is determined by the application timing to the lens frame piezoelectric element. Since the applied voltage may be discontinuous such as binary, the circuit can be simplified as compared with the case where the voltage value must be continuously changed as in the prior art. Moreover, although the case where it was employ | adopted as the example was demonstrated and demonstrated to a digital camera, it may be employ | adopted not only in this but the normal camera which takes a photograph on a roll-shaped photographic film, or a video camera, In addition, although an example in which a piezoelectric element is employed in the clutch mechanism that switches the coupling state of the lens holding frame to the drive shaft has been described, the present invention is not limited thereto, and the lens holding frame includes an electromagnet and is attracted by the electromagnet. The frictional force with respect to the drive shaft may be controlled by the above, or the coupling state with the drive shaft may be controlled by the magnetic force of the electromagnet.
[0114]
【The invention's effect】
As described above, according to the lens driving device of the present invention, it is possible to suppress the secular change of the friction coefficient of the portion where the lens holding frame and the driving rod are in contact with each other.
[Brief description of the drawings]
FIG. 1 is a front view of a camera that employs a first embodiment of a lens driving device of the present invention.
FIG. 2 is a rear view of the camera shown in FIG.
3 is an internal configuration diagram of the camera shown in FIGS. 1 and 2. FIG.
FIG. 4 is a diagram illustrating a case where the first drive unit is viewed from the front side of the camera.
FIG. 5 is a diagram illustrating a driving principle toward the front side of a camera.
FIG. 6 is a diagram showing a change in voltage applied to a piezoelectric element for a drive shaft.
FIG. 7 is a diagram showing the principle of driving to the back side of the camera.
FIG. 8 is a graph showing a change in voltage applied to the drive shaft piezoelectric element when the drive unit is moved to the back side of the camera.
FIG. 9 is a diagram illustrating an example of a voltage applied to a piezoelectric element for a drive shaft.
FIG. 10 is a flowchart of a routine that is started when preliminary shooting ends.
FIG. 11 is a diagram showing a part of a second embodiment of the lens driving device of the present invention.
12 is a diagram illustrating a case where the lens driving unit illustrated in FIG. 7 is viewed from the front side of the camera.
FIG. 13 is a diagram showing a state of movement of the lens frame according to the aspect shown in (c) of Table 1.
FIG. 14 is a diagram showing how the lens frame moves when the piezoelectric element is operated as shown in (d) of Table 1.
FIG. 15 is a flowchart of a routine that is started after preliminary shooting is performed in a camera that adopts the modes shown in (c) and (d) in the present embodiment.
[Explanation of symbols]
1 Camera
10 Rear lens
11 Front lens
12 Lens barrel
13a Viewfinder objective window
13b Viewfinder eyepiece
14 Release button
15 Flash emission window
16 microphone
17a Function switch
17b Mode switch
18 LCD panel
19 Zoom switch
20 Speaker
100, 300 Lens driving device
110 1st drive part
111 Zoom lens holding frame
111a recess
111b Movable part
112 First piezoelectric element
112a First piezoelectric element driver
113 Zoom lens
120 Second drive unit
121 Focus lens holding frame
121a recess
121b Movable part
122 Second piezoelectric element
122a Second piezoelectric element driver
123 Focus lens
130 Piezoelectric element for drive shaft
130a Piezoelectric element driver for drive shaft
140 Drive shaft
150 Guide shaft
210 CCD image sensor
211 A / D conversion circuit
212 Image signal processing circuit
213 Buffer memory
214 Image Input Controller
215 AF / AE arithmetic circuit
216 CPU
217 Bus
218 memory
219 Key controller
220 Compression processing circuit
221 Media controller
222 Image display control circuit
223 External storage device
310 Drive unit
311 Lens holding frame
312 Upper piezoelectric element
3112a, 3113a recess
3112b, 3113b Movable part
312a Upper piezoelectric element driver
313 Lower piezoelectric element
313a Lower piezoelectric element driver
314 lens group
320 Lower drive shaft
330 Piezoelectric element for lower drive shaft
340 Upper drive shaft
350 Piezoelectric element for upper drive shaft

Claims (2)

Non spared a single drive rod extending in the direction of an optical axis, together when holding the lens group, the coupling state between the driving rod, the driving by the fixed state and the driving rods secured before SL drive rod A plurality of lens holding frames having a clutch mechanism that can be switched between a driving state and the lens holding in cooperation with the operation of the clutch mechanism by reciprocating the driving rod in a direction in which the driving rod extends. In the lens driving device including the first electro-mechanical conversion element that moves the frame in the optical axis direction ,
The lens holding frame has a movable portion, and a concave portion that sandwiches the drive rod is formed between the movable portion and other portions excluding the movable portion, and the movable portion and the movable portion are excluded in the concave portion. A lens driving device characterized in that a second electro-mechanical conversion element for changing a distance from another portion is provided to constitute the clutch mechanism . Non spared and two drive rods extending in the optical axis direction, holds the lens group, the coupling state between the front SL drive rod, the drive by the fixed state and the driving rods secured before SL drive rod A lens driving device comprising: a plurality of lens holding frames having a clutch mechanism that can be switched between driving states; and a first electro-mechanical conversion element that reciprocates the driving rod in a direction in which the driving rod extends . ,
The lens holding frame has two movable portions, and two concave portions are formed in which the two drive rods are sandwiched separately by the other portions excluding the two movable portions and the two movable portions. Each of the two recesses is provided with a second electro-mechanical conversion element for changing the distance between the movable part and the other part excluding the movable part, thereby constituting the clutch mechanism. And
A lens drive characterized in that each of the plurality of lens holding frames is independently moved along an optical axis in cooperation with the first electro-mechanical conversion element and the second electro-mechanical conversion element. apparatus.

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