JP2007121494A - Lens barrel and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a further miniaturized imaging apparatus by obtaining a smaller lens barrel configured such that a particular lens group of a bending optical system is moved by using a motor and a lead screw. <P>SOLUTION: The lens barrel includes: a plurality of lens groups for guiding subject light; a reflecting face disposed between the plurality of lens groups and used to bend an optical axis; a drive source used to move at least one of the plurality of lens groups. In the lens barrel, the drive source is disposed behind the reflecting face. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lens barrel configured to include a bent imaging optical system and to move a predetermined lens group, and an imaging apparatus including the lens barrel.

  Conventionally, cameras equipped with a zoom lens are commercially available. The zoom lens is configured to change the focal length (zooming) by moving a plurality of lens groups constituting the optical system to a desired position along the optical axis and changing the interval therebetween.

  There are roughly two types of methods for moving the lens group along the optical axis. The lens frame is engaged with the linear guide, and the lens frame is moved linearly by rotating the cam cylinder or helicoid. A shaft is arranged almost in parallel, and this shaft is used as a guide shaft for rectilinear guide. A sleeve through which the guide shaft passes is formed in the lens frame, and the lens frame is slid directly along the guide shaft using a motor and a lead screw. There is something that lets you move straight ahead. A DC motor or a stepping motor is generally used as a drive source for moving these lens groups.

  On the other hand, a camera having a so-called bending optical system in which a reflecting surface is disposed in an optical system and an optical axis is bent is known. A camera provided with this bending optical system has an advantage that the lens barrel does not protrude from the front of the camera at the time of shooting, and the form of the camera does not change even when zooming is performed. For the movement of the lens group in this bending optical system, the latter method using a motor and a lead screw is frequently used.

In such an imaging optical system using a bending optical system, a motor and a lead screw for moving the two lens groups after being bent by the reflecting surface are arranged on one side of the optical axis on the image plane side from the reflecting surface. There is known a lens barrel in which an iris drive motor is disposed on the other side (see, for example, Patent Document 1).
Japanese Patent Laying-Open No. 2005-121882 (FIGS. 6 to 16)

  Even in the camera provided with the above-described bending optical system, there is a great demand for reducing the size and thickness of the outer shape, and accordingly, the built-in imaging optical system is required to be further reduced in size and thickness.

  FIG. 5 shows an example of a motor layout of a lens barrel that includes an imaging optical system using a conventional bending optical system. OA shown in the figure is an optical axis of incident light, 11 is a first lens on the object side, and 6 is an image sensor. The optical axis OA is bent by a prism (not shown) disposed behind the first lens 11 and guided to the image sensor 6. When the two optical systems are moved inside the optical system having a short overall length as in this example, the motors 21 and 22 must be arranged on both sides of the prism, and the motor diameters on the prism and both sides are unavoidable. Thus, the size in the width direction is determined, which is an obstacle to miniaturization.

  In the arrangement of the lens barrel described in Patent Document 1, the thickness direction is the diameter of the optical system, the length direction is the total length of the lens, the width direction is the diameter of the optical system, the diameter of the lens drive motor, and the iris drive. It was determined by the sum of the motor diameters, and further downsizing in the width direction was difficult.

  In view of the above problems, the present invention provides a lens barrel having a configuration in which a predetermined lens group in a bending optical system is moved using a motor and a lead screw, thereby obtaining a smaller lens barrel, thereby further reducing the size. It is an object of the present invention to obtain an image pickup apparatus.

  The above problem is solved by the following configuration.

  1) A plurality of lens groups for guiding subject light, a reflecting surface arranged between the plurality of lens groups and bending an optical axis, and for moving at least one lens group among the plurality of lens groups A lens barrel having a driving source, wherein the driving source is disposed on the back side of the reflecting surface.

  2) The lens barrel according to 1), wherein the lens group moved by the driving source is a lens group located closer to the image plane than the reflecting surface.

  3) The drive axis of the drive source is disposed in a direction substantially orthogonal to a plane including the optical axis on the object side from the reflection surface and the optical axis on the image plane side from the reflection surface, and is closer to the image plane side than the reflection surface. The lens barrel according to 1) or 2), wherein a lens group is moved by driving a lead screw arranged substantially parallel to the optical axis.

  4) The lens barrel according to any one of 1) to 3), wherein a plurality of the driving sources are arranged on the back surface of the reflecting surface, and the lead screw is arranged so as to sandwich the optical axis on the image surface side from the reflecting surface.

  5) An imaging apparatus comprising the lens barrel according to any one of 1) to 4).

  According to the present invention, it is possible to obtain a small lens barrel having a shortened width direction by moving a predetermined lens group of a bending optical system using a motor and a lead screw. By providing, a smaller imaging device can be obtained.

  Hereinafter, the present invention will be described in detail with reference to embodiments, but the present invention is not limited thereto.

  FIG. 1 is a diagram illustrating an example of an internal arrangement of main constituent units of a camera 100 that is an imaging apparatus including a lens barrel according to the present invention. FIG. 3 is a perspective view of the camera 100 as viewed from the subject side.

  As shown in the figure, in the camera 100, a lens barrel 50 according to the present invention including a foldable imaging optical system capable of zooming is arranged along the front surface as shown in the figure, and the opening 51 captures a subject light flux. Has been placed. Although not shown, a lens barrier that opens and closes the opening 51 is disposed.

  Reference numeral 52 denotes a flash light emission window. Reference numeral 53 denotes a flash unit including a reflector, a xenon tube, other main capacitors, a circuit board, and the like disposed behind the flash light emission window. Reference numeral 54 denotes a card-type image recording memory. A battery 55 supplies power to each part of the camera 100. The image recording memory 54 and the battery 55 can be inserted and removed from a lid (not shown).

  A release button 56 is arranged on the upper surface of the camera 100, and a shooting preparation operation, that is, a focusing operation and a photometric operation are performed by pushing the first button, and a shooting exposure operation is performed by pushing the second button. Reference numeral 57 denotes a main switch that switches the camera 100 between an operating state and a non-operating state. When switched to the operating state by the main switch 57, when a lens barrier is provided, the lens barrier is opened and the operation of each unit is started. When the main switch 57 is switched to the non-operating state, the lens barrier is closed and the operation of each unit is ended.

  On the back surface of the camera 100, an image display unit 58 that is configured by a display element such as an LCD or an organic EL and displays images and other character information is disposed. Although not shown, a zoom button for zooming up and down, a playback button for playing back a captured image, a menu button for displaying various menus on the image display unit 58, and a desired function are selected from the display. An operation member such as a selection button is arranged.

  Although not shown, each part is connected between these main constituent units and a circuit board on which various electronic components are mounted is arranged to drive and control each main constituent unit. Yes. Furthermore, it is provided with an external input / output terminal, a strap attaching portion, a tripod seat and the like.

  FIG. 2 is a cross-sectional view showing a foldable imaging optical system capable of zooming, which is included in the lens barrel 50 according to the present embodiment. This figure shows a state at the time of widening, which is cut along a plane including two optical axes before and after bending.

  As shown in the figure, OA is the optical axis before bending, and OB is the optical axis after bending. The outside of the lens barrel 50 is composed of a main body 10A and a main body 10B.

  Reference numeral 1 denotes a first lens group. The first lens group 1 is a prism that is a reflecting member having a reflecting surface that bends the optical axis OA in a substantially right angle direction with a lens 11 that is disposed toward the subject with an optical axis of OA. 12 and a lens 13 arranged with the optical axis OB bent by the prism 12 as an optical axis. The first lens group 1 is a lens group fixed to the main body 10A.

  Reference numeral 2 denotes a second lens group, which is incorporated in the second lens group frame 2k. The second lens group is a lens group that moves together with the second lens group frame 2k during zooming (hereinafter also referred to as zooming).

  Reference numeral 3 denotes a third lens group. The third lens group 3 is a lens group that is incorporated in the main body 10B and does not move.

  Reference numeral 4 denotes a fourth lens group, which is incorporated in the fourth lens group frame 4k. The fourth lens group is a lens group that moves integrally with the fourth lens group lens frame 4k during zooming and during focus adjustment (hereinafter also referred to as focusing).

  Reference numeral 5 denotes an optical filter in which an infrared light cut filter and an optical low-pass filter are stacked, and is assembled to the main body 10B. Reference numeral 6 denotes an image sensor, which uses a charge coupled device (CCD) type image sensor, a complementary metal-oxide semiconductor (CMOS) type image sensor, or the like. The imaging element 6 is assembled to the attachment member 8, and the attachment member 8 is assembled to the main body 10 </ b> B together with the imaging element 6. A flexible printed circuit board 7 is connected to the image sensor 6 and is connected to other circuits in the camera. A shutter unit 9 is fixed to the main body B10B.

  Further, a first motor 21 and a second motor 22 which are driving sources for moving the second lens group frame 2k and the fourth lens group 4k, respectively, are disposed behind and on the back side of the prism 12 having a reflecting surface. . The first motor 21 and the second motor 22 are, for example, stepping motors, and are connected to and driven by a flexible printed board (not shown).

  In addition, the drive shafts (rotation axes) of the first motor 21 and the second motor 22 are arranged in a direction substantially orthogonal to a plane including the optical axis OA on the object side from the reflection surface and the optical axis OB on the image plane side from the reflection surface. Has been.

  FIG. 3 schematically shows an example of a mechanism for driving a lead screw disposed substantially parallel to the optical axis OB on the image plane side from the reflection surface by the rotation of the drive shaft (rotation shaft) of the first motor 21. It is a perspective view.

  As shown in the figure, the rotation of the drive shaft OM of the first motor 21 arranged on the back surface of the reflecting surface of the prism 12 is transmitted to the orthogonal lead screw 33 by the staggered gears 31 and 32. ing.

  However, the present invention is not limited to this, and a configuration in which a pinion gear is disposed on the drive shaft OM of the first motor 21 and a crown gear is disposed on the rotation shaft OR of the lead screw 33, and the rotation of the drive shaft OM and the lead screw 33 of the first motor 21. A configuration in which bevel gears are arranged on both sides of the shaft OR may be employed.

  By decelerating at the direction changing portion of the drive shaft, the torque required for lens movement can be reduced, and even a motor with a small motor torque can be used, and the lens barrel can be further downsized.

  FIG. 4 is a schematic diagram showing the moving mechanism and the internal schematic structure of the second lens group 2 and the fourth lens group 4 of the lens barrel 50 according to the present embodiment. This figure shows the optical system after the prism 12, and shows a state in which the second lens group 2 and the fourth lens group 4 are in the wide position. In the following drawings, in order to avoid duplication of explanation, the same reference numerals are given to the same functional members.

  As shown in the figure, a guide shaft 15 is provided in a sleeve 2s formed integrally with the second lens group frame 2k and a rotation locking portion 4m formed integrally with the fourth lens group frame 4k. It has been. Further, a guide shaft 16 is provided on a rotation locking portion 2m formed integrally with the second lens group frame 2k and a sleeve 4s formed integrally with the fourth lens group frame 4k. Thereby, the second lens group lens frame 2k and the fourth lens group lens frame 4k are slidable along the guide shafts 15 and 16 in the direction of the optical axis OB.

  The driving force of the first motor 21 disposed on the back side of the prism 12 is transmitted to the lead screw 33 disposed substantially parallel to the optical axis OB by the staggered gears 31 and 32 described above.

  The second lens group lens frame 2k has a bifurcated projection 2t formed on the sleeve 2s, and this projection 2t is engaged with a drive member 33k that moves as the lead screw 33 rotates. Thereby, by the rotation of the first motor 21, the second lens group lens frame 2k engaged with the drive member 33k slides along the guide shafts 15 and 16 and moves in the direction of the optical axis OB. ing. Although not shown, the drive member 33k is rotationally locked.

  Similarly, the driving force of the second motor 22 disposed on the back side of the prism 12 is transmitted to the lead screw 36 disposed substantially parallel to the optical axis OB by the same staggered gears 34 and 35.

  The fourth lens group frame 4k has a bifurcated projection 4t formed on the sleeve 4s, and this projection 4t is engaged with a drive member 36k that moves as the lead screw 36 rotates. As a result, the rotation of the second motor 22 causes the fourth lens group lens frame 4k engaged with the drive member 36k to slide along the guide shafts 15 and 16 and move in the direction of the optical axis OB. ing. Although not shown, the drive member 36k is rotationally locked.

  As a result, the second lens group 2 and the fourth lens group 4 are moved by a set amount from the position in the illustrated wide state toward the third lens group 3 for zooming. Further, the fourth lens group 4 is focused by moving further from the position moved by zooming.

  Although not shown, a position sensor that detects the presence of the second lens group 2 and a position sensor that detects the presence of the fourth lens group 4 are arranged. For example, a photo interrupter is used as the position sensor. In this position sensor, the shielding portions formed on the second lens group lens frame 2k and the fourth lens group lens frame 4k are respectively shielded between the light projecting / receiving systems of the position sensors, or the light projecting / receiving system of the position sensor. The lens group controls the rotation direction and amount of rotation of the first motor 21 and the second motor 22 with reference to the switching position from the shield state to the non-shield state. Position control is performed.

  As described above, the motor that is the driving source is arranged on the back side of the reflecting surface, the driving direction of the motor is changed, transmitted to the lead screw, and the lens group is moved by the rotation of the lead screw. As a result, it is possible to reduce the dimension in the width direction due to the bulge of the side surface of the motor as compared with the case where the motor is coaxially arranged on the extension line of the lead screw. Furthermore, the lead screw can be placed at a position that could not be placed because the motor interferes with other parts in the conventional layout, and the lead screw is placed closer to the optical axis, that is, closer to the guide shaft. Thus, it is possible to obtain a lens barrel that can be further downsized in the width direction. Further, by providing this lens barrel, it is possible to obtain a further downsized imaging device.

  In the above embodiment, the motor shaft and the rotation axis of the lead screw are arranged substantially orthogonal to each other. However, the present invention is not limited to this, and it is of course possible to have an oblique configuration. is there.

  In addition, an example in which two motors are arranged on the back surface of the reflecting surface and applied to a zoom lens barrel that moves the two lens groups has been described. However, a single-focus lens is formed of a bending optical system, and the back surface of the reflecting surface is formed. Needless to say, the present invention can also be applied to a case where one motor is used for focusing.

It is a figure which shows an example of the internal arrangement | positioning of the main structural unit of the camera which is an imaging device provided with the lens barrel which concerns on this invention. 1 is a cross-sectional view illustrating a foldable imaging optical system that is variable in magnification and is contained in a lens barrel according to the present embodiment. It is the perspective view which showed typically an example of the mechanism which drives the lead screw arrange | positioned substantially parallel to the optical axis OB of the image surface side rather than a reflective surface by rotation of the drive shaft (rotating shaft) of a 1st motor. It is a schematic diagram which shows the moving mechanism of the 2nd lens group of a lens barrel and the 4th lens group which concern on this Embodiment, and an internal schematic structure. An example of a motor layout of a lens barrel including an imaging optical system using a conventional bending optical system is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st lens group 2 2nd lens group 2k 2nd lens group frame 3 3rd lens group 3k 3rd lens group frame 4 4th lens group 5 Optical filter 6 Imaging element 12 Prism 15, 16 Guide shaft 21 1st Motor 22 Second motor 33, 36 Lead screw 50 Lens barrel 100 Camera

Claims (5)

A plurality of lens groups for guiding subject light, a reflective surface arranged between the plurality of lens groups and bending an optical axis, and a drive source for moving at least one lens group among the plurality of lens groups In a lens barrel having
A lens barrel characterized in that the driving source is disposed on the back side of the reflecting surface. The lens barrel according to claim 1, wherein the lens group moved by the driving source is a lens group positioned on the image plane side with respect to the reflecting surface. The drive axis of the drive source is disposed in a direction substantially orthogonal to a surface including the optical axis on the object side from the reflection surface and the optical axis on the image plane side from the reflection surface, and the optical axis on the image plane side from the reflection surface The lens barrel according to claim 1, wherein the lens group is moved by driving a lead screw disposed substantially parallel to the lens barrel. 4. The drive device according to claim 1, wherein a plurality of the drive sources are disposed on the back surface of the reflection surface, and the lead screw is disposed so as to sandwich the optical axis on the image surface side with respect to the reflection surface. The lens barrel described. An imaging apparatus comprising the lens barrel according to claim 1.

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