JP2009192581A - Lens-barrel and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens-barrel allowing thinning, without interfering with a guide shaft when an object side lens group is retracted during non-imaging. <P>SOLUTION: The lens-barrel holds an imaging optical system having the object side lens group getting incident with a light beam from an object, and advanced and retracted along the first optical axis, a reflection optical element for reflecting the light beam emitted from the object side lens group along the second optical axis substantially orthogonal to the first optical axis, and an image face side lens group arranged on the second optical axis and for image-focusing, on an image face, the light beam reflected by the reflection optical element, the reflection optical element is guided, during non-imaging, by the guide shaft arranged in substantial parallel to the second optical axis, to be evacuated in a position different from a position in an imaging time, the object side lens group is evacuated in a space positioned with the reflection optical element in the imaging time, and the guide shaft is arranged in a position more separated with respect to the object than an end positioned most separatedly from the object in the reflection optical element. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lens barrel configured to hold an imaging optical system having a reflective optical element that reflects a light beam from an object in a direction substantially orthogonal to an incident optical axis, and to be thin when not photographing, and the lens mirror The present invention relates to an imaging apparatus having a trunk.

  2. Description of the Related Art Conventionally, there has been known a lens barrel in which a prism having a reflecting surface is arranged in an imaging optical system, and an incident light beam from an object is reflected at a right angle and guided to an imaging surface. According to this lens barrel, it is not necessary to use a complicated collapsible mechanism, and the imaging device is thin both when photographing and when not photographing.

On the other hand, in recent image pickup apparatuses, it is desired to mount an image pickup optical system with a higher zoom ratio, and a structure in which an object side lens group located on the object side of the prism is advanced and retracted in the optical axis direction has been proposed. . Such an object-side lens group moves forward away from the prism at the time of photographing, and retracts toward the prism when not photographing. However, when the object-side lens group is retracted during non-photographing, if the prism is positioned behind the object-side lens group, it cannot be sufficiently retracted. Therefore, in order to further reduce the object-side lens group during non-photographing and thin the imaging device, the prism is retracted laterally only during non-photographing, and the object-side lens group is retracted into the space where the prism was located. A lens barrel has been proposed (see Patent Documents 1 and 2).
JP 2003-169236 A JP 2006-259665A

  In Patent Document 1, the prism is retracted along two guide axes provided orthogonal to the optical axis of the object-side lens group located on the object side of the prism, and the object-side lens is interlocked with the retracting operation. The group is retracted in the direction of the optical axis. However, when the imaging optical system is a lens having a small F number, that is, a bright lens, the aperture of the object side lens group is formed larger than the apertures of the other lens groups. The group is not so large. For this reason, even if the object side lens unit moves backward, it does not interfere with the guide shaft.

  Also in Patent Document 2, the prism is retracted along two guide axes provided orthogonal to the optical axis of the object side lens group, and the object side lens group is retracted in the optical axis direction in conjunction with the retracting operation. I am letting. Although this object side lens group is formed with a large aperture, it is a diagram that interferes with the guide shaft located on the object side when retracted, and about the configuration to avoid such interference Not listed.

  However, when the imaging optical system is highly zoomed, if the optical system has a brightness that does not interfere with shooting, the object-side lens group must have a large aperture to some extent. In order to move the object-side lens unit forward by a considerable amount during zooming and to move it back as much as possible during non-shooting, the lens barrel that holds the object-side lens unit is composed of a plurality of lens barrels. The lens barrel is engaged with the cam groove and the cam pin, and a part of the lens barrel is rotated to move the object side lens group forward and backward.

  Further, when the imaging optical system is highly variable in magnification, the object side lens group may be composed of a plurality of lenses, and the distance between the lenses may be changed with the magnification. In this case, it is particularly necessary to configure the lens barrel that holds the object side lens group with a plurality of lens barrels.

  In this regard, in Patent Document 1, since the object side lens unit is configured to simply go straight with a small aperture, it is difficult to achieve high zooming of the imaging optical system as described above.

  On the other hand, in Patent Document 2, the lens interval of the object side lens unit does not change due to zooming, but the object side lens unit and the prism approach at the wide angle end, and the object side lens unit and prism at the telephoto end. Are far apart. In addition, the lens barrel of the object side lens unit is retracted into the image pickup apparatus when not photographing. In order to increase the amount of movement of the object side lens group in this way, it is essential that the lens barrel that holds the object side lens group is composed of a plurality of lens barrels. The lens barrel is composed of three lens barrels. And although not described, in order to pay out three lens barrels, a rotating lens barrel is essential.

  However, in Patent Document 2, when the object side lens unit is retracted, the drawing is such that it interferes with the guide shaft located on the object side, and at least one lens barrel needs to rotate. If the tube is not cut out considerably, the guide shaft cannot escape and is difficult to realize.

  The present invention has been made in view of such problems, and retracts a reflecting optical element such as a prism along a guide axis provided substantially orthogonal to the optical axis of the object-side lens group during non-photographing. Related to the lens barrel that retracts the object side lens group in the optical axis direction, and when the object side lens group retracts during non-photographing, it does not interfere with the guide shaft and achieves a reduction in thickness An object of the present invention is to propose a lens barrel that can be used, and an image pickup apparatus including the lens barrel.

The object is achieved by the invention described below.
1. An object-side lens group that allows a light beam from the object to enter and advance and retreat along the first optical axis, and a second optical axis that substantially reflects the light beam emitted from the object-side lens group to the first optical axis. An imaging optical system comprising: a reflective optical element that reflects in the direction of the optical axis; and an image plane side lens group that is disposed on the second optical axis and forms an image on the image plane of the light beam reflected by the reflective optical element. Hold and
At the time of non-photographing, the reflective optical element is guided by a guide shaft arranged substantially parallel to the second optical axis and retracted to a position different from the position at the time of photographing, and the reflective optical element is located at the time of photographing. A lens barrel configured so that the object-side lens group moves back into the space,
The lens barrel, wherein the guide shaft is disposed at a position further away from the object than an end portion of the reflective optical element that is farthest from the object.
2. 2. The lens barrel according to 1, wherein the lens barrel that holds the object side lens group includes a plurality of cylindrical members, and at least one cylindrical member moves forward and backward while rotating.
3. 3. The lens mirror according to claim 1 or 2, wherein the object side lens group moves forward toward the object side during photographing, and the reflective optical element moves to a space where the object side lens group was located during non-photographing. Torso.
4). The imaging optical system is a variable magnification optical system, the plurality of lenses constituting the object side lens group move along the first optical axis, and the plurality of lenses constituting the image side lens group is the second optical axis. The lens barrel according to any one of 1 to 3, wherein the lens barrel moves along the lens.
5. A stop member is provided to stop the movement of the reflective optical element when the reflective optical element is moved from the retracted position to the photographing position, and a click mechanism is provided to prevent the reflective optical element from retreating from the photographing position. 5. The lens barrel according to any one of 1 to 4, characterized in that:
An imaging apparatus comprising the lens barrel according to any one of 6.1 to 5.

  The lens barrel of the present invention and an image pickup apparatus including the lens barrel retract a reflecting optical element such as a prism along a guide axis provided substantially orthogonal to the optical axis of the object side lens group when not photographing. The object side lens group is retracted in the optical axis direction in conjunction with the retracting operation. The guide shaft is disposed at a position further away from the object than the end of the reflective optical element that is farthest away from the object, so that the object-side lens group is held. There is no interference with the guide shaft when the tube member is retracted. Therefore, the cylindrical member can be sufficiently retracted, and a thin lens barrel as a whole is achieved.

  First, an embodiment of a camera as an example of an imaging apparatus provided with a lens barrel according to the present invention will be described.

  FIG. 1 is a perspective view showing an example of an internal arrangement of main constituent units of a camera.

  In this camera, a lens barrel 1 holding an imaging optical system capable of zooming and having a reflective optical element is arranged horizontally as shown in the figure. The first lens L1 disposed closest to the object (subject) side in the imaging optical system is located in front of the camera. In addition, you may provide the lens barrier made into the open state which exposes the 1st lens L1, and the closed state which coat | covers the 1st lens L1.

  A flash light emission window 3 is disposed on the front surface, and a flash unit 4 including a reflector, a xenon tube, a main capacitor, a circuit board, and the like is disposed behind the flash light emission window 3.

  A battery 5 supplies power to each part of the camera. The battery 5 and the image recording memory (not shown) can be inserted and removed from a lid (not shown).

  A release button 6 is arranged on the upper surface of the camera, and the photometric operation and the distance measuring operation of the camera are performed by depressing the first step, and the exposure operation is performed by depressing the second step. Reference numeral 7 denotes a main switch button, which switches the camera between an operating state and a non-operating state.

  A zoom button 8 for changing the magnification of the imaging optical system of the lens barrel 1 between the wide-angle end and the telephoto end is disposed on the back of the camera. In addition, an image display unit 9 configured by an LCD or the like and displaying an image and other information is disposed. Further, although not shown in the drawing, operation members such as a playback button for reproducing a photographed image, a menu button for displaying various menus on the image display unit 9, and a selection button for selecting a desired function from the display are arranged. .

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

  Next, the lens barrel 1 will be described with reference to FIG. 2A is a sectional view of the lens barrel in which the imaging optical system is moved to the telephoto end during photographing, and FIG. 2B is a sectional view of the lens barrel in which the imaging optical system is moved to the wide-angle end during photographing. FIG. 2 and FIG. 2C are cross-sectional views of the lens barrel when not photographing.

  The imaging optical system of the lens barrel includes a first lens L1, a second lens L2, a prism P (reflection optical element), a third lens L3, a fourth lens L4, and an optical filter F in order from the object (subject) side. An optical image of an object is formed on an image plane of an image sensor (not shown) disposed in the vicinity of the optical filter F by the imaging optical system.

  In addition, a light beam from an object is incident on the first lens L1, and the first lens L1 and the second lens L2 constitute an object-side lens group. The first lens L1 and the second lens L2 move forward along the first optical axis O1 during shooting, and move back along the first optical axis O1 when not shooting. Further, at the time of photographing, the first lens L1 advances and retreats along the first optical axis O1 with zooming, but the second lens L2 does not move.

  The prism P is located behind the second lens L2 at the time of photographing, and reflects the light beam emitted from the second lens L2 in the direction of the second optical axis O2 orthogonal to the first optical axis O1. The prism P retracts in the direction of the second optical axis O2 when not photographing.

  The third lens L3 and the fourth lens L4 move along the second optical axis O2 while changing the distance between the lenses along with zooming at the time of photographing, and constitute an image plane side lens group. Further, the fourth lens L4 moves in accordance with the change in the subject distance, and focuses the light image of the object on the image sensor.

  The optical filter F has an infrared cut filter and an optical low-pass filter laminated and fixed.

  The first lens L <b> 1 is held by the barrel 11, the barrel 11 is held by the cam barrel 13 via the rectilinear barrel 12, and the cam barrel 13 is further held by the housing 60. A cam pin (not shown) is erected from the outer peripheral surface of the lens barrel 11, passes through the rectilinear tube 12, and engages with a cam groove (not shown) provided on the inner peripheral surface of the cam tube 13. When the cam cylinder 13 is rotated with respect to the housing 60 by driving a motor (not shown), the lens barrel 11 is linearly moved by the action of the cam groove and the cam pin without being restricted by the linear movement cylinder 12 and rotating.

  Note that the number of tube members collectively referring to the lens barrel 11, the rectilinear tube 12, and the cam tube 13 is not limited to three, and may be any number. However, at least one of the cylindrical members is configured to advance and retract while rotating.

  The second lens unit L2 is held by the lens barrel 21, and the lens barrel 21 is driven by a motor (not shown) to move forward during shooting and to move backward when not shooting. However, it does not move back and forth with zooming during shooting.

  The prism P is held by a prism holding frame 31, and the prism holding frame 31 moves while being guided by two guide shafts 32 that are substantially parallel to the second optical axis O2 and overlapped in the direction perpendicular to the paper surface. Further, the guide shaft 32 is disposed at a position further away from the object than the end portion Pa of the prism P located farthest from the object. The method for driving the prism holding frame 31 will be described later.

  The third lens L3 and the fourth lens L4 are respectively held by the lens barrels 41 and 51, and are guided by two guide shafts 42 that are parallel to the second optical axis O2 and overlapped in the direction perpendicular to the paper surface. Moving. The interval between the two guide shafts 42 is larger than the length of the prism P and the prism holding frame 31 in the direction perpendicular to the paper surface, and the prism P and the prism holding frame 31 can move between the two guide shafts 42. .

  The barrel 41 and the barrel 51 are each screwed with a screw shaft (not shown) provided with a long male screw, and by driving two motors (not shown) to rotate the screw shafts, respectively. The lens barrel 41 and the lens barrel 51 move independently of each other.

  Next, a driving method and the like of the prism holding frame 31 will be described with reference to FIG. FIG. 3 is a perspective view of the prism holding frame 31 and the like.

  In FIG. 3, the prism holding frame 31 holds the prism P. Further, the prism holding frame 31 moves while being guided by two guide shafts 32 arranged substantially parallel to the second optical axis O2.

  A motor holding portion 31a projects in the lateral direction of the prism holding frame 31, and a prism driving motor 33 is fixed. The rotation shaft 33a of the prism driving motor 33 penetrates the motor holding portion 31a and projects downward, and the first gear 34 is fixed to the rotation shaft 33a. A second gear 35 that meshes with the first gear 34 is rotatably supported by the motor holding portion 31a. Further, the long rack plate 36 is fixed to the housing 60 in parallel with the guide shaft 32, and the second gear 35 meshes with the rack plate 36.

  When the prism holding frame 31 is moved, the prism driving motor 33 is rotated. Then, the first gear 34 rotates and the second gear 35 also rotates. Since the second gear 35 meshes with the fixed rack plate 36, the second gear 35 moves along the rack plate 36. That is, the prism holding frame 31 moves while being guided by the two guide shafts 32.

  Next, the operation of the imaging optical system will be described with reference to FIGS.

  When moving from the telephoto end as shown in FIG. 2A to the wide-angle end as shown in FIG. 2B or when moving from the wide-angle end to the telephoto end during shooting, the zoom button 18 shown in FIG. 1 is pressed. Then, each of the lens barrels 11, 41, 51 is driven by a dedicated motor and moves independently, so that the distance between the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 changes, Scaling to the desired zoom magnification.

  Next, when switching from the shooting state to the non-shooting state, the main switch button shown in FIG. 1 is pressed. Then, the lens barrels 41 and 51 are moved to positions close to the optical filter F by the dedicated motor. Subsequently, the prism driving motor 33 is rotated to retract the prism holding frame 31 near the lens barrel 41. Next, as shown in FIG. 2C, the lens barrel 21, the cam barrel 13, the rectilinear barrel 12 and the lens barrel 11 are moved by a dedicated motor and retracted to the space where the prism holding frame 31 was located. When the cam cylinder 13 or the like is retracted, the prism holding frame 31 is retracted to a position where it does not interfere, and the two guide shafts 42 are disposed so as not to interfere.

  Further, since the two guide shafts 32 are disposed at a position further away from the object than the end portion Pa of the prism P at the position farthest from the object, the object side lens group There is no interference with the guide shaft 32 when the cam cylinder 13 or the like to be held is retracted. Accordingly, the cam barrel 13 and the like can be sufficiently retracted, and a thin lens barrel as a whole can be achieved by projecting only the space for arranging the two guide shafts 32 from the rear portion of the housing 60. .

  In order to retract the prism holding frame 31, it is necessary to cut out the rear portions of the cam barrel 13, the rectilinear barrel 12, and the lens barrel 11 on the third lens L3 side. However, since the prism holding frame 31 is retracted in a state where the cam cylinder 13, the rectilinear cylinder 12 and the lens barrel 11 in FIG. 2 (B) are stationary, it is sufficient to provide a partial notch 14, which is functionally problematic. Nothing to become.

  On the other hand, when switching from the non-photographing state to the photographing state, the zoom button 18 shown in FIG. 1 is pressed. Then, the lens barrel 11 and the lens barrel 21 are moved forward by the dedicated motor and moved to the wide-angle end position. Next, the prism driving motor 33 is rotated, and the prism holding frame 31 is set at a photographing position where the prism P can reflect the light beams from the first lens L1 and the second lens L2 to the third lens L3 and the fourth lens L4. Move. Subsequently, the lens barrels 41 and 51 are moved to the wide-angle end position by the dedicated motor.

  If the moved prism P does not stop at a normal position at the time of shooting, the light beam emitted from the object side lens group along the first optical axis O1 is not reflected by the prism P to the position of the second optical axis O2. , Optical performance decreases. For this purpose, it is conceivable to provide a stopper so that when the prism holding frame 31 moves from the retracted position to the photographing position, it does not move further than the photographing position. However, as described above, since the prism holding frame 31 is moved by the first gear 34, the second gear 35, and the rack plate 36, the prism holding frame 31 may be slightly retracted from the photographing position due to backlash between the gears. .

  Therefore, as shown in FIG. 4, a click mechanism is provided so that the prism holding frame 31 does not move backward due to backlash. 4A is a cross-sectional view in which the upper and lower centers of the prism holding frame 31 are cut horizontally, and FIG. 4B is a rear view of the click spring.

  As shown in FIG. 4A, the housing 60 is provided with a stopper 60a (stop member) with which the end 31b of the prism holding frame 31 comes into contact. Thereby, the prism holding frame 31 does not move further than the normal photographing position.

  A concave portion 31 b is provided on the back surface of the prism holding frame 31. A click spring 60b is formed integrally with the housing 60, and a tip end portion 60c of the click spring 60b is urged toward the prism holding frame 31 and presses against the recess 31b. When the prism holding frame 31 is moved to the normal photographing position and the end 31c of the prism holding frame 31 comes into contact with the stopper 60a, the tip 60c of the click spring 60b is inserted into the recess 31b. In (A), the left end of the tip 60c abuts on the left wall of the recess 31b. Therefore, the prism holding frame 31 does not move backward due to the backlash of each gear.

  Note that when the prism holding frame 31 is retracted to the right during non-photographing, the tip 60c of the click spring 60b comes out of the recess 31b.

  In the above embodiment, the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 may be composed of a single lens, or may be composed of a plurality of lenses. Good.

  In addition, a reflecting mirror may be used as the reflecting optical element instead of the prism P.

  Furthermore, the first optical axis O1 and the second optical axis O2 do not necessarily have to be orthogonal to each other, either of which may be slightly inclined.

  Further, the two guide shafts 32 may not necessarily be parallel to the second optical axis O2, and may be slightly inclined.

  The lens configuration of the imaging optical system is not limited at all.

  In the imaging optical system shown in FIG. 2, the second lens L2 does not advance or retract during zooming, but may be configured to advance or retract.

It is a perspective view which shows an example of the internal arrangement | positioning of the main structural unit of a camera. It is sectional drawing of the lens barrel at the time of moving the imaging optical system to the telephoto end and the wide-angle end at the time of imaging, and at the time of non-imaging. It is a perspective view, such as a prism holding frame. It is sectional drawing and a rear view which show a click mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens barrel 7 Main switch button 8 Zoom button 11 Lens barrel 12 Straight advance barrel 13 Cam barrel 31 Prism holding frame 32, 42 Guide shaft 33 Prism drive motor 60b Click spring L1 First lens L2 Second lens L3 Third lens L4 Fourth lens P Prism F Optical filter O1 First optical axis O2 Second optical axis

Claims (6)

An object-side lens group that allows a light beam from the object to enter and advance and retreat along the first optical axis, and a second optical axis that substantially reflects the light beam emitted from the object-side lens group to the first optical axis. An imaging optical system comprising: a reflective optical element that reflects in the direction of the optical axis; and an image plane side lens group that is disposed on the second optical axis and forms an image on the image plane of the light beam reflected by the reflective optical element. Hold and
At the time of non-photographing, the reflective optical element is guided by a guide shaft arranged substantially parallel to the second optical axis and retracted to a position different from the position at the time of photographing, and the reflective optical element is located at the time of photographing. A lens barrel configured so that the object-side lens group moves back into the space,
The lens barrel, wherein the guide shaft is disposed at a position further away from the object than an end portion of the reflective optical element that is farthest from the object. The lens barrel according to claim 1, wherein the lens barrel that holds the object side lens group includes a plurality of cylindrical members, and at least one cylindrical member moves forward and backward while rotating. 3. The imaging apparatus according to claim 1, wherein the object-side lens group moves forward toward the object side during photographing, and the reflective optical element moves to a space where the object-side lens group was located during non-photographing. The lens barrel described. The imaging optical system is a variable magnification optical system, the plurality of lenses constituting the object side lens group move along the first optical axis, and the plurality of lenses constituting the image side lens group is the second optical axis. The lens barrel according to any one of claims 1 to 3, wherein the lens barrel moves along the lens. A stop member is provided to stop the movement of the reflective optical element when the reflective optical element is moved from the retracted position to the photographing position, and a click mechanism is provided to prevent the reflective optical element from retreating from the photographing position. The lens barrel according to any one of claims 1 to 4, wherein the lens barrel is provided. An imaging apparatus comprising the lens barrel according to claim 1.

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