Image pickup apparatus

An image pickup apparatus of the present invention includes: a fixed frame; a zoom lens holding frame; a focus lens holding frame; a focus driving unit and a zoom driving unit; an image pickup device; a base plate that is coupled to the fixed frame and displaceably supports the image pickup device; an X driving unit that drives the image pickup device in an X direction; and a Y driving unit that drives the image pickup device in a Y direction, wherein the focus driving unit is placed in an upper left portion of the fixed frame, the zoom driving unit is placed in a right side portion, and further the Y driving unit is placed in an upper right corner of the base plate and the X driving unit is placed in a lower right corner.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of Japanese Application No. 2009-117798 filed in Japan on May 14, 2009, the contents of which are incorporated herein by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image pickup apparatus having an image shake correction function.

2. Description of the Related Art

As a conventional image pickup apparatus including an image shake correction device that supports an image pickup device drivably in a two-dimensional direction (X and Y directions) perpendicular to a lens optical axis for image shake correction, an apparatus disclosed in Japanese Patent Application Laid-Open Publication No. 2008-48220 includes a base as a fixed plate member on which a lens barrel having an image pickup optical system and an image pickup device supported by an image shake correction device are mounted.

The conventional image pickup apparatus includes a first movable frame displaceable in a Y direction, and a second movable frame displaceable in an X direction with respect to the first movable frame, and an image pickup device is mounted on the second movable frame. Further, on the base, when viewed from front along the lens optical axis, a first driving section including a Y direction driving motor of the image shake correction device and a second driving section including an X direction driving motor are placed in upper and lower right positions. Further, in upper and lower left positions on a front surface of the base, a focus driving section including a focus motor and a gear driving mechanism, and a zoom driving section including a zoom motor and a gear driving mechanism are placed so as to be secured to a fixed frame of a lens barrel unit.

SUMMARY OF THE INVENTION

The present invention provides an image pickup apparatus including: a fixed frame; an image pickup optical system having a focus lens group and a zoom lens group; a focus lens holding frame holding the focus lens group; a zoom lens holding frame holding the zoom lens group; a focus driving unit provided on an outer peripheral portion of the fixed frame, and including a focus motor for focus driving of the focus lens group and a rotation transmitting mechanism of the focus motor; a zoom driving unit provided on the outer peripheral portion of the fixed frame and including a zoom motor for zoom driving of the zoom lens group and a rotation transmitting mechanism of the zoom motor; an image pickup device that receives an optical image formed via the image pickup optical system; a base member that is coupled to the fixed frame, and supports the image pickup device displaceably in a first direction and a second direction perpendicular to the first direction in a plane parallel to a light receiving surface of the image pickup device; a first driving section provided on the base member, and including a first motor that drives the image pickup device in the first direction; and a second driving section including a second motor that drives the image pickup device in the second direction, wherein the base member includes at least a first corner portion in which the first driving section is mounted, a second corner portion in which the second driving section is mounted, a third corner portion located on a side opposite to the first corner portion via an optical axis of the image pickup optical system, and having a notch that a protruding portion from the fixed frame of the focus driving unit enters, and a fourth corner portion located on a side opposite to the second corner portion via the optical axis of the image pickup optical system, the zoom driving unit is configured so that the zoom motor is placed between the first driving section and the second driving section in an optical axis direction of the image pickup optical system with respect to the fixed frame, and the rotation transmitting mechanism of the zoom motor is placed overlapping the first driving section or the second driving section on a side closer to a subject of the image pickup optical system than the first driving section or the second driving section, and a member placement escape portion is formed in the fourth corner portion of the base member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A lens barrel that constitutes an image pickup apparatus according to an embodiment of the present invention will be described with reference toFIGS. 1 to 18.

A lens barrel1of the present embodiment is a retractable lens barrel including an image pickup optical system constituted by a first group lens having positive refractive power, a second group lens having negative refractive power, a third group lens having positive refractive power, and a fourth group lens having positive refractive power, with each movable frame member being retracted in a non-photographing state, and can be further mounted in a digital camera as an image pickup apparatus having an image shake correction function with an image pickup device movable on an image forming plane of the optical system.

In the description below, a photographing lens optical axis of the image pickup optical system is denoted by “O”. In the optical axis O direction, a subject side direction is a front direction and an image forming side direction is a rear direction. Also, a direction perpendicular to the optical axis O, which is a lateral direction viewed from a front side, is an X direction as a first direction, and particularly a right direction is a +X side. A direction perpendicular to the optical axis O and the X direction (vertical direction) is a Y direction as a second direction, and particularly an upper direction is a +Y side. A plane perpendicular to the optical axis O is an XY plane.

When the lens barrel1is in a retracted state, as shown inFIG. 6, movable frame members are retracted to a fixed frame13described later and brought into substantially tight contact with each other, and an entire length of the barrel is reduced. On the other hand, when the lens barrel1is in a photographable zoom wide-angle state and a photographable zoom telephoto state, as shown inFIGS. 7 and 8, the movable frame members are advanced forward in the optical axis O direction, and a first group frame4, a cam frame5, a rotating frame11, and the like described later protrude. In the lens barrel1, an image pickup device96described later is supported movably on the XY plane perpendicular to the optical axis O, and the image pickup device96is controlled to be displaced on the XY plane so as to correct camera shake based on a camera shake detection signal detected by the digital camera in photographing.

Main components of the lens barrel1are sequentially placed from the front in the optical axis O direction as shown inFIGS. 1 and 2. The lens barrel1includes a barrier unit3for opening/closing a front surface of a first group lens21described later, a first group frame4as a zoom lens holding frame holding the first group lens21, a second group frame6as a zoom lens holding frame holding a second group lens22, a cam frame5for driving the first group frame4and the second group frame6forward and backward, a third group frame7as a zoom lens holding frame holding a third group lens23, which includes a shutter/diaphragm unit8on a rear side, a float key9as a frame member for controlling rotation of the first and second group frames, a movable frame10for driving the cam frame5forward and backward and controlling rotation of the third group frame7and the float key9, a rotating frame11for rotationally driving the cam frame5and driving the third group frame7forward and backward, a fourth group frame12as a focus lens holding frame holding a fourth group lens24, a fixed frame13that is a fixed frame member for supporting the rotating frame11so as to be rotationally movable forward and backward and controlling rotation of the frame10, and is fixedly supported by a camera body, a zoom driving unit50that rotationally drives the rotating frame11, a focus driving unit60that drives the fourth group frame12forward and backward, and a shake correction image pickup unit90that is assembled to a base plate14as a base member, holds the image pickup device96, and drives the image pickup device96to be displaced on the plane perpendicular to the optical axis O direction.

The fixed frame13has a cylindrical portion, houses the frame members in an inner peripheral portion, and has a back surface to which the base plate14of the shake correction image pickup unit90is secured. The fixed frame13has a rotating frame cam groove13adiagonal to the optical axis O direction along the cylinder inner peripheral portion, a movable frame straight guide groove13cand a fourth group frame straight guide groove13bin the optical axis O direction, and a gear housing recess13dthat houses a long gear54described later. The zoom driving unit50is placed along a right side of a cylinder outer peripheral portion, and the focus driving unit60is placed in an upper left position of the cylinder outer peripheral portion. A light shielding ring35is secured to a front surface.

The rotating frame11is a cylindrical frame member, and a rear end outer periphery thereof fits in the inner peripheral portion of the fixed frame13so as to be rotationally movable forward and backward. A cam follower11bis placed on the rear end outer periphery, and slidably fits in the cam groove13ain the fixed frame13. A gear portion11athat meshes with the long gear54is provided in a predetermined range of the rear end outer periphery. A third group frame cam groove11cdiagonal to the optical axis O direction, and a cam frame straight groove11dare provided in an inner peripheral portion of the rotating frame11.

The rotating frame11is rotationally driven by rotation of the long gear driven by the zoom driving unit50, and then driven forward and backward in the optical axis O direction while being rotated along the cam groove13a. To a front surface outer peripheral portion of the rotating frame11, the light shielding ring34and a decorative ring33are mounted.

The movable frame10is a cylindrical frame member, has a rear end bayonet-connected to the rotating frame11, and is moved forward and backward together with the rotating frame11in the optical axis O direction and supported rotatably with respect to the rotating frame11. A guide pin10bprotruding from the rear end outer periphery engages the straight guide groove13cin the fixed frame13. Thus, the movable frame10is moved forward and backward together with the rotating frame11in a rotation-restricted state.

In a circumferential portion of the movable frame10, a cam frame cam groove10cpassing through inner and outer peripheries and diagonal to the optical axis O, a third group frame straight guide groove10epassing through the inner and outer peripheries, and a float key straight guide groove10fin an inner peripheral portion are provided.

The float key9is a cylindrical frame member, has a rear end bayonet-connected to the cam frame5, and is moved forward and backward together with the cam frame5in the optical axis O direction and supported rotatably with respect to the cam frame5. The float key9has a guide protrusion9aprotruding from a rear end outer periphery, a first group frame straight guide groove9cin an outer peripheral portion, and a second group frame straight guide groove9bpassing through inner and outer peripheries.

The guide protrusion9aon the float key9slidably fits in the straight guide groove10fin the movable frame10. Thus, the float key9is supported movably forward and backward in the optical axis O direction together with the cam frame5in the rotation-restricted state by the movable frame10.

The cam frame5is a cylindrical frame member, fits in and is integrated into the inner peripheral portion of the movable frame10so as to be rotationally movable forward and backward. A cam follower5dprotruding from a rear outer peripheral portion is placed on the cam frame5, and a straight guide pin38protruding outward is fitted in and secured to a center of the cam follower5d. In the inner peripheral portion of the cam frame5, as shown inFIG. 18, three pairs of first group frame cam grooves5aand sub-cam grooves5bhaving the same cam curve (cam groove central locus) and three second group frame cam grooves5care provided. In a developed view of the cam frame inFIG. 18, θ denotes a rotation angle with respect to the first group frame4and the second group frame6of the cam frame5, a (+) direction denotes an advance rotational direction from the retracted state, and a (−) direction denotes a retraction rotational direction to the retracted state.

Cam followers36and37described later of the first group frame4fit in the pair of the first group frame cam groove5aand the sub-cam groove5b, the cam groove5afunctions to drive the first group frame4forward and backward, while the sub-cam groove5bfunctions to prevent removal of the cam follower when an external force in a thrust direction is applied to the first group frame4by an impact or the like.

The second group frame cam grooves5care constituted by cam grooves with different groove widths. When the lens barrel1is in the photographable wide-angle state to the photographable telephoto state, a cam follower39described later of the second group frame6fits in a cam groove without a gap among the cam grooves5c, and when the lens barrel1is in the retracted state, the cam follower39fits in a cam groove with a gap among the cam grooves5c. This prevents a jam between the first group frame4and the second group frame5when the lens barrel1is in the retracted state.

The cam follower5dslidably fits in the cam groove10cin the movable frame10, the straight guide pin38passes through the cam groove10cand then slidably fits in the straight groove11din the rotating frame11(FIG. 9). Thus, the cam frame5is rotated together with the rotating frame11and supported movably forward and backward in the optical axis O direction along the cam groove10cin the movable frame10.

When the cam frame5is advanced together with the rotating frame11in the photographable telephoto state as shown inFIG. 8, the cam follower5dis moved close to a thin part10don the front side of the cam groove10cin the movable frame10(FIG. 1). If a forward external force (tensile force) is applied to the first group frame4or the cam frame5exposed to the outside in this state, the external force may be applied to the thin part10don the front side of the movable frame10via the cam follower5dto damage the thin part10d. However, the present embodiment adopts a structure in which a front end surface of the movable frame10abuts against an inner side step11e(FIG. 8) in the rotating frame11, thereby preventing the external force from damaging the thin part10dof the movable frame10.

The barrier unit3includes four barrier blades3a, and is covered with the decorative ring2and mounted to the front surface of the first group frame4. The barrier blade3ais retracted with an advancing operation of the first group frame4from the retraction position to open the front surface of the first group lens21. Also, the barrier blade3ais brought into a closed position with retraction of the first group frame4from the photographing position to close the front surface of the first group lens21.

The first group frame4is a cylindrical frame member, and fits in the inner peripheral portion of the cam frame5movably forward and backward in the rotation-restricted state. The first group frame4holds the first group lens21as a zoom lens group, and three pairs of cam followers36and37are secured to an outer peripheral portion of the first group frame4. A guide protrusion (not shown) that slidably fits in the straight guide groove9cin the float key9is provided in an inner peripheral portion of the first group frame4.

The cam followers36and37of the first group frame4slidably fit in the cam groove5aand the sub-cam groove5b, respectively, of the cam frame5, and the first group frame4is moved forward and backward with rotation and forward and backward movement of the cam frame5with rotation of the first group frame4being controlled by the straight guide groove9cin the float key9. The cam follower37and the sub-cam groove5bare provided to prevent removal of the cam follower when the external force is applied to the first group frame4due to a fall or the like as described above.

The second group frame6is a cylindrical frame member, fits in the inner peripheral portion of the float key9movably forward and backward in the rotation-restricted state, and is integrated into the rear side of the first group frame4. The second group frame6holds the second group lens22as a zoom lens group, and to an outer peripheral portion, three guide protrusions6aare secured and the cam follower39is secured so as to protrude outward from the center of the guide protrusion6a.

The guide protrusion6afits in and passes through the straight guide groove9bin the float key9, and fits the cam follower39in the cam groove5cin the cam frame5. Thus, the second group frame6is moved forward and backward by rotation and forward and backward movement of the cam frame5in the rotation-restricted state.

The third group frame7is a cylindrical frame member, fits in the inner peripheral portion of the float key9, and is integrated into the rear side of the second group frame6movably forward and backward in the rotation-restricted state. The third group frame7holds the third group lens23as a zoom lens group, and supports the shutter/diaphragm unit8on a back side inner peripheral portion relatively movably in the optical axis O direction. A third group lens retainer plate7ais secured to a front side of the third group frame7. A guide protrusion7bis provided on an arm portion protruding outward of the third group frame7, and a cam follower41is secured to the guide protrusion (FIG. 3).

The third group frame7fits the guide protrusion7bin the straight guide groove10ein the movable frame10, and after the guide protrusion7bpasses through the straight guide groove10e, the cam follower41is fitted in and assembled to the cam groove11cin the rotating frame11. Thus, the third group frame7is moved forward and backward in the optical axis O direction in the rotation-restricted state with rotation of the rotating frame11.

A shutter blade25for opening/closing a photographing optical path and a diaphragm blade26for adjusting an amount of photographing light are incorporated into the shutter/diaphragm unit8. A compression spring42is inserted between the shutter/diaphragm unit8and the third group frame7, and the shutter/diaphragm unit8and the third group frame7are urged in directions apart from each other.

In the photographable state of the lens barrel1, the shutter/diaphragm unit8and the third group frame7are a predetermined distance apart from each other, while in the retracted state, the third group frame7is brought close to the base plate14described later to compress the compression spring42, and the shutter/diaphragm unit8and the third group frame7are brought into substantially tight contact with each other. In the retracted state, the shutter blade25and the diaphragm blade26are driven to open positions, and a rear portion of the third group lens23enters opened apertures. This further brings the shutter/diaphragm unit8and the third group frame7into substantially tight contact with each other. Further, the shutter/diaphragm unit8and the third group frame7are brought extremely close to the fourth group lens24.

A conical coil spring18as an urging member for urging the second and third group frames is inserted between the second group frame6and the third group frame7, and the second group frame6and the third group frame7are urged to be apart from each other in the optical axis O direction (FIGS. 6 to 8). As described above, the second group frame6and the third group frame7are urged to be apart from each other, and when the lens barrel1is in the photographable state including the retracted state, fitting backlashes between the cam follower39of the second group frame6and the cam groove5cin the cam frame5, and the cam follower41of the third group frame7and the cam groove11cin the rotating frame11are eliminated, thereby allowing the second group frame6and the third group frame7to be driven forward and backward in the optical axis O direction without backlash.

The conical coil spring18has a bent portion18abent toward an inner diameter side at a large diameter side end turn portion. When the conical coil spring18is integrated between the second group frame6and the third group frame7, the large diameter side end turn portion is abutted against an end surface of the second group frame6. When the lens barrel1is retracted to the retracted state, as shown inFIG. 6, the conical coil spring18is compressed and brought into substantially tight contact, but the bent portion18aprevents an adjacent winding from fitting in the large diameter side end turn portion and avoids an unrestored state of the spring18.

The fourth group frame12is placed behind the shutter/diaphragm unit8movably forward and backward in the rotation-restricted state. The fourth group frame12holds the fourth group lens24as a focus lens group in a middle aperture, and has two arm portions extending outward. A guide protrusion12cis provided on one arm portion, and a guide shaft hole12a, a feed screw insertion hole12b, and a sensor shielding piece12dare provided on the other arm portion.

A guide shaft65supported by the fixed frame13slidably fits in the guide shaft hole12a. The guide protrusion12cincludes two minute cylindrical portions formed to protrude on opposite sides (circumferential direction) around the optical axis O and extending in parallel with the optical axis O, and slidably fits in the straight guide groove13bin the fixed frame13. Thus, the fourth group frame12is supported movably forward and backward in the optical axis O direction along the guide shaft65and the straight guide groove13bvia a feed screw66by a driving force of a focus driving unit60described later.

The guide protrusion12cincludes the two minute cylindrical portions in a width direction as described above. Thus, even if there is a slight displacement around the optical axis O due to dimensional accuracy of the fourth group frame12, both the cylindrical portions of the guide protrusion12cabut against the straight guide groove13bin the fixed frame13, thereby allowing a satisfactory fitting state without uneven contact to be maintained.

When an alignment mechanism of the fourth group lens24is applied to the fourth group12, for example, when an eccentricity adjusting mechanism is incorporated into the guide shaft65, the guide protrusion12cis constituted by the minute cylindrical portion as described above, and thus the satisfactory fitting state between the straight guide groove13band the guide protrusion12ccan be maintained even with changes of the position of the fourth group frame12due to alignment. The guide protrusion12cmay include two minute spherical portions protruding in a width direction rather than the minute cylindrical portion.

As shown inFIGS. 2 and 12, the zoom driving unit50is placed on a right side (left side inFIG. 12) of a cylinder outer peripheral portion of the fixed frame13, and includes a zoom motor51constituted by a DC motor, a gear case lid52, and a gear train53and a long gear54athat constitute a rotation transmitting mechanism.

The gear case lid52is secured to the right side of the fixed frame13from the back side, and has shaft holes that support shaft portions of the gear train53and the long gear54.

The zoom motor51is supported by the fixed frame13, and positioned between an X driving motor71and a Y driving motor81described later mounted to the base plate14, and a worm gear is secured to an output shaft in the Y direction.

The gear train53includes a worm wheel that meshes with a worm gear of the zoom motor51, and a reduction gear train that meshes with the worm wheel and the long gear54.

The long gear54is housed in the gear housing recess13din the fixed frame13in a direction parallel to the optical axis O, and meshes with the gear portion11aof the rotating frame11.

In the zoom driving unit50, when the zoom motor51is rotationally driven in retraction driving and zoom driving of the lens barrel1, the rotating frame11is rotationally driven via the long gear54to advance or retract the lens barrel1.

The focus driving unit60is placed in the upper left position on the cylinder outer peripheral portion as described above, and includes, as shown inFIGS. 4,12and17, a focus motor61constituted by a step motor, a gear case lid62, a guide shaft65that constitutes a rotation transmitting mechanism, a feed screw66, a gear train63, a nut64, a fourth group frame biasing spring67, and a focus origin detecting PI68as an origin detector constituted by a photo interrupter.

The gear case lid62is secured to the upper left position of the fixed frame13from the back side, and supports shaft ends of the guide shaft65and the feed screw66parallel to the optical axis O.

The focus motor61is supported by the fixed frame13, and a pinion that meshes with the gear train63is mounted to an output shaft in the direction parallel to the optical axis O.

The guide shaft65is placed in parallel with the optical axis O, and slidably fits in the guide shaft hole12ain the fourth group frame12, and the shaft end is supported by the fixed frame13and the gear case lid62.

The feed screw66is driven by the focus motor61via the gear train63. A nut64is threaded on the feed screw66, and an end surface of the feed screw insertion hole12bof the fourth group frame12abuts against a rear surface of the nut64. The nut64has a rotation-restricting protrusion guided by the fixed frame13in the rotation-restricted state.

The fourth group frame biasing spring67is constituted by a tensile spring, is provided between the fixed frame13and the fourth group frame12, urges the fourth group frame12forward, and abuts the end surface of the feed screw insertion hole12bin the fourth group frame12against the nut64.

The PI68is secured to the fixed frame13, and the sensor shielding piece12dof the fourth group frame12can pass through the inside of the PI68. When the camera is turned on, the PI68detects passage of the sensor shielding piece12dof the fourth group frame12, and focus origin position information of the fourth group frame12is captured by a camera control section (not shown).

A rear end of the focus driving unit60including the gear case lid62protrudes rearward from the back surface of the fixed frame13, and the protruding portion enters a notch provided in the third corner portion14dat a left upper corner of the base plate14of the shake correction image pickup unit90described later.

In the focus driving unit60, when the focus motor61is rotationally driven in focus driving of the lens barrel1, the feed screw66is rotationally driven and the nut64is moved forward and backward. The fourth group frame12is moved forward and backward in the optical axis O direction with the end surface of the feed screw insertion hole12babutting against the nut64.

Now, first, second, third and fourth group lenses that constitute the image pickup optical system of the lens barrel1will be described. The first group lens21is constituted by a cemented lens of a negative meniscus lens21awith a convex surface on a subject side and a biconvex positive lens21bin order from the subject side, and moved toward the subject side from a wide-angle end to a telephoto end. The first group lens21is applied to advantageously reduce a thickness and a diameter, lens aberrations are cancelled each other to advantageously correct aberrations of the first group lens21, and prevent aberration changes in obtaining a wider angle or a higher zooming ratio.

The second group lens22is constituted by a second group lens front group22aand second group lens rear groups22band22cin order from the subject side. The second group lens front group22ais constituted by a negative meniscus lens with a convex surface on the subject side, and the second group lens rear groups22band22care constituted by a biconcave negative lens and a positive meniscus lens with a convex surface on the subject side.

The second group lens22is moved toward an image surface side from the wide-angle end to an intermediate state while increasing a distance from the first group lens21and reducing a distance from the third group lens23, and moved toward the subject side from the intermediate state to the telephoto end while increasing a distance from the first group lens21and reducing a distance from the third group lens23. At the telephoto end, the second group lens22is located closer to the subject side than at the wide-angle end.

The third group lens23includes a third group lens front group23aand a third group lens rear group23bin order from the subject side. The third group lens23ais constituted by a biconvex positive lens, and the third group lens rear group23bis constituted by a negative meniscus lens with a convex surface on the subject side. The third group lens23is moved toward the subject side from the wide-angle end to the telephoto end.

The fourth group lens24is constituted by one positive meniscus lens with a convex surface on the subject side. The fourth group lens24is driven forward and backward in focusing, further moved toward the subject side while increasing a distance from the group lens23from the wide-angle end to the intermediate state, and slightly moved toward the image surface side while increasing a distance from the third group lens23from the intermediate state to the telephoto end. At the telephoto end, the fourth group lens24is located closer to the subject side than at the wide-angle end.

The image pickup optical system is configured as described above, and thus a synthesized system of the first group lens21and the second group lens22brought close to each other at around the wide-angle end has a symmetric power arrangement including positive refractive power (first group lens21), negative refractive power (second group lens front group22a), and positive refractive power (second group lens rear groups22band22c) in order from the subject side.

A synthesized system of the third group lens23and the fourth group lens24also has a symmetric power arrangement including positive refractive power (third group lens front group23a), negative refractive power (third group lens rear group23b), and positive refractive power (fourth group lens24) in order from the subject side.

A synthesized system of the second group lens22and the third group lens23brought close to each other at around the telephoto end has symmetric arrangement including negative refractive power (second group lens front group22a), positive refractive power (second group lens rear groups22band22c), positive refractive power (third group lens front group23a), and negative refractive power (third group lens rear group23b) in order from the subject side.

This facilitates correction of Petzval sum, coma aberration, magnification chromatic aberration, and spherical aberration at around the wide-angle end, and correction of Petzval sum, coma aberration, and magnification chromatic aberration at around the telephoto end, thereby easily obtaining a wider angle and a higher zooming ratio. A principal point of the third lens group is easily set closer to the subject, thereby easily ensuring a zooming ratio.

Further, the fourth group lens24is constituted by one positive lens component to advantageously reduce the thickness in retraction. The fourth group lens24has a main function of separating an exit pupil from the image surface, and thus can reduce positive refractive power. Thus, the above-described configuration is advantageous for reducing the size and cost.

The shake correction image pickup unit90is constituted by a movable image pickup unit mounted to the back surface of the fixed frame13, and includes the base plate14as a base member, a Y frame15supported on the base plate14movably in the Y direction on the XY plane, an X frame16supported on the Y frame15movably in the X direction on the XY plane, an image pickup device unit95fixedly supported on the X frame16, an X driving unit70as a first driving section, and a Y driving unit80as a second driving section.

The base plate14is a substantially rectangular frame member having a middle aperture14a, and an outline projection shape viewed from front having a first corner portion14bat a lower right position (lower left position inFIG. 11) around the optical axis O, a second corner portion14cat an upper right position (upper left position inFIG. 11), a third corner portion14dat an upper left position (upper right position inFIG. 11), and a fourth corner portion14eat a lower left position (lower right position inFIG. 11), and is fixed to the back surface of the fixed frame13. When the base plate14is secured to the fixed frame13, the shake correction image pickup unit90needs to be precisely positioned on the XY plane with respect to the optical axis O of the lens barrel, and thus the base plate14is secured to the fixed frame13with positioning holes14fand14g(FIG. 11) in the base plate14fitted on positioning pins on the fixed frame13.

The third corner portion14dhas a notch, and the rear end of the focus driving unit60including the gear case lid62enters the notch as described above. The fourth corner portion14eis a member placement escape portion along the outer periphery of the fixed frame13. The escape portion is for placing a tripod female screw portion of the digital camera to which the lens barrel1is mounted.

The Y frame15is constituted by a frame member having an aperture15a, placed in the middle aperture14ain the base plate14, and supported slidably in the Y direction by two guide shafts91and92while being urged by biasing springs.

The X frame16is constituted by a frame member having an aperture16a, placed in the aperture15ain the Y frame15, and supported slidably in the X direction by two guide shafts93and94while being urged by biasing springs.

An image pickup device unit95includes an image pickup device support plate98, an image pickup device96mounted to an FPC (flexible printed circuit board)103and secured to the image pickup device support plate98, and constituted by a CCD or a CMOS, and an optical filter97such as an optical low-pass filter or an infrared ray cutting and absorbing filter provided on a front side of the image pickup device96. A surface of the optical low-pass filter may be directly coated with a near-infrared sharp cut coat.

The image pickup device unit95is mounted to the X frame16with the image pickup device support plate98secured to the back surface of the X frame16by a screw, and the image pickup device96and the optical filter97placed in the aperture16ain the X frame16.

An X driving unit70is assembled to the front side of the first corner portion14bat the upper right position of the base plate14, and placed overlapping a rear position of the gear train53of the zoom driving unit50on the outer peripheral portion of the fixed frame13(FIG. 10). The X driving unit70includes an X driving unit support plate72, an X driving motor71as a first motor constituted by a step motor, an intermediate gear73that meshes with a pinion of an output shaft of the X driving motor71, a feed screw74in the X direction to which the intermediate gear73is secured, a nut75, and a PI (photo interrupter)76as an X frame initial position detecting sensor. Instead of the position detector of the PI76, a position detector may be placed that detects an initial position with a combination of a photoreflector or a hall element and a flat permanent magnet.

The nut75is threaded on the feed screw74in the rotation-restricted state of the X frame16, supported slidably in the X direction, and receives a biasing force of a biasing spring and abuts against a U-shaped notch16bin the X frame16. Thus, when the X driving motor71is rotationally driven in the shake correction operation, the feed screw74drives the nut75and the X frame16to be displaced in the direction.

A Y driving unit80is assembled to a front side of the second corner portion14cof the base plate14, and placed in an upper position of the zoom motor51on the outer peripheral portion of the fixed frame13. The Y driving unit80includes a Y driving unit support plate82, a Y driving motor81as a second motor constituted by a step motor, an intermediate gear83that meshes with a pinion of an output shaft of the Y driving motor81, a feed screw84in the Y direction to which the intermediate gear83is secured, a nut85, and a PI (photo interrupter)86as a Y frame initial position detecting sensor.

The nut85is threaded on the feed screw84in the rotation-restricted state of the Y frame15, supported slidably in the Y direction, and receives a biasing force of a biasing spring and abuts against a U-shaped notch15bin the Y frame15. Thus, when the Y driving motor81is rotationally driven in the shake correction operation, the feed screw84drives the nut85and the Y frame15to be displaced in the Y direction.

In the shake correction image pickup unit90, the Y frame15and the X frame16are driven to be displaced on the XY plane with camera shake in an image pickup device exposure operation by camera shake correction, and after the camera shake correction operation is finished, or immediately after a power switch of the digital camera is turned on, the Y frame15and the X frame16are returned to respective initial intermediate positions based on output signals of the PI86and the PI76. When the Y frame15and the X frame16are in the initial intermediate positions, a central position of a light receiving surface of the image pickup device96matches the optical axis O.

In the shake correction image pickup unit90, the X driving unit70and the Y driving unit80may be placed on the base plate14in a vertically inverse manner to the placement described above such that the X driving unit70is placed in the first corner portion14band the Y driving unit80is placed in the second corner portion14c.

In the above-described lens barrel1, an exterior color of the zoom motor51, the focus motor61, the Y driving motor81, and the X driving motor71is black, or for example, silver other than black, and an exterior color of the fixed frame13and the base plate14is a color other than black, for example, silver, or black. The components and the motors thus have different exterior colors, and thus an assembling state in an assembling process is checked, for example, the zoom motor51, the focus motor61, the Y driving motor81, and the X driving motor71being mounted to the above-described predetermined positions on the fixed frame13and the base plate14is checked, and the base plate14can be secured to the fixed frame13.

Next, arrangement on an FPC (flexible printed circuit board) for electrical connection between an electric control element of each component unit of the lens barrel1and a control section of the digital camera will be described with reference toFIGS. 2,12to16.

The electrical connection FPC included in the lens barrel1includes an FPC101for electrical connection between the zoom and focus driving units50and60and the shutter/diaphragm control unit8and the camera electrical control section, an FPC102for electrical connection between the X and Y driving units70and80and the camera electrical control section, and an FPC103for electrical connection between the image pickup device unit95and the camera electrical control section.

The FPC101includes a zoom motor connector portion101a, a focus motor connector portion101b, a focus position detecting PI connector portion101f, a connecting extending portion101cto the focus motor connector portion, a left extending portion101d, a camera electric control connector portion101g, a shutter/diaphragm control unit FPC connector portion101e, and further a zoom position detecting PI connector and a PR connector (FIG. 2).

In the FPC101, as shown inFIG. 10, the zoom motor connector portion101aplaced at one end is connected to a terminal portion of the zoom motor51. The left extending portion101dof the FPC101is extended to the left along the upper outer peripheral portion of the fixed frame13, and the focus motor connector portion101bbranching off at the connecting extending portion101cin the middle is connected to a terminal portion of the focus motor61. The left extending portion101dpasses through the upper outer periphery of the fixed frame13, and then the PI connector portion101fbranching off rearward is connected to the PI68. After passing through the upper outer periphery of the fixed frame13, the branching shutter/diaphragm control unit FPC connector portion101eis connected to a shutter/diaphragm control unit FPC (not shown). The FPC101passes leftward through the upper outer periphery of the fixed frame13, and then the camera electric control connector portion101gextending to the left is connected to the camera electric control section (not shown).

The FPC102includes an X motor connector portion102a, a Y motor connector portion102b, PI connector portions102cand102d, a laterally extending portion102e, a downward extending portion102f, and a camera electric control connector portion102g(FIG. 2).

In the FPC102, the Y motor connector portion102bis connected to the Y driving motor81, the PI connector portion102dis connected to the PI86, and further the PI connector portion102cis connected to the PI76, then the laterally extending portion102eis passed through along an outer periphery of a right side surface of the fixed frame13. Further, the X motor connector portion102ais connected to the X driving motor71, and then the downward extending portion102fis passed through along a lower outer periphery of the fixed frame. The camera electric control connector portion102gextending to the left is connected to the camera electrical control section (not shown).

The FPC103includes an image pickup device mounting connecting portion103a, a V-shaped bent portion103bhaving a middle slit for supporting the image pickup device96displaceably on the XY plane, and a camera electric control connector portion103c(FIG. 2).

In the FPC103, after the mounting connecting portion103ais connected to the image pickup device96, the back surface of the base plate14is passed through to the left via the V-shaped bent portion103bhoused in the FPC bent portion housing recess14f(FIG. 6) of the base plate14, and the camera electric control connector portion103cextending to the left is connected to the camera electrical control section (not shown).

The retraction operation, the advance operation, the shake correction operation, or the like of the lens barrel1of the present embodiment having the above-described configuration will be described.

The lens barrel1is set to the photographable wide-angle state or telephoto state shown inFIGS. 7 and 8by the advance operation from the retracted state shown inFIG. 6. Specifically, the zoom motor51is driven while being controlled by the camera control section, and the rotating frame11is rotated and driven to advance. With the rotation and advance of the rotating frame11, the barrier unit3is first opened, and the first group frame4, the second group frame6, the third group frame7, and the shutter/diaphragm unit8are moved to respective zoom positions based on distance measuring signals. The focus motor61is driven based on the distance measuring signals, the fourth group frame12is advanced to the focus position, and the lens barrel1enters a photographable state.

In shake correction photographing, when exposure of the image pickup device96is performed, the X driving motor71and the Y driving motor81are driven while being controlled by the control section of the digital camera based on a camera shake signal detected by a camera shake detecting sensor of the digital camera, this causes the Y frame15and the X frame16to be displaced, and the image pickup device96is driven in a direction for correcting the camera shake. The image pickup device96placed on the X frame16and driven in the camera shake correcting direction outputs an image pickup signal without camera shake.

When the lens barrel1is retracted from the photographable state to the retracted state, the zoom motor51and the focus motor61are driven to retract the movable frame members toward the fixed frame13to enter the retracted state. In the retracted state, the movable frame members are brought into tight or substantially tight contact with each other, and the first group lens22to the fourth group lens24are also brought into substantially tight contact with each other. This can reduce an entire length of the lens barrel1in the optical axis O direction in the retracted state.

Particularly, the first group frame4, the second group frame6, and the third group frame7are retracted so as to be brought close to each other. Specifically, as described above, the cam grooves5cin the cam frame5in which the cam follower39of the second group frame6fits are constituted by cam grooves with different groove widths, and when the lens barrel1is in the retracted state, the cam follower39fits in a cam groove with a large fitting gap.

Specifically, when the lens barrel1is in the retracted state, the cam follower39is movable by a fitting gap with respect to the cam groove5c. Thus, when the lens barrel1is in the retracted state, and for example, the first group frame4interferes with the second group frame6due to variations in shape size, the second group frame6is moved rearward against the biasing force of the conical coil spring18. Thus, when the first group frame4interferes with the second group frame6, the lens barrel1can be retracted without the retraction operation being interrupted.

On the other hand, as described above, in retraction, the shutter blade25and the diaphragm blade26of the shutter/diaphragm control unit8are driven to a position with an opened aperture, and with retraction of the lens barrel1, the shutter/diaphragm control unit8is moved forward with respect to the third group frame7against the biasing force of the compression spring42.

Thus, in the retracted state, a rear portion of the third group lens23and a holding frame thereof enter the aperture in the shutter/diaphragm control unit8, the shutter/diaphragm control unit8and the third group frame7can be further brought into substantially tight contact with each other, and simultaneously brought extremely close to the fourth group lens24. Further, the shutter/diaphragm control unit8causes a part of the third group lens23having a smaller diameter than the fourth group lens24to enter the aperture in the shutter/diaphragm control unit8, thereby reducing sizes of the aperture and the unit itself, suitably reducing the length of the lens barrel1in the optical axis direction in the retracted state without increasing cost, and reducing a thickness of the camera unit. Further, the image pickup optical system includes the first group lens21constituted by two lenses and the fourth group lens24constituted by one positive lens, thereby further reducing the length in the optical axis O direction of the image pickup optical system in the tight contact state in retraction.

The image pickup apparatus according to the present invention can reduce the entire length of the lens barrel1in the optical axis O direction in the retracted state for the above-described reasons.

As described above, the zoom driving unit50for driving the lens barrel forward and backward is placed on the right side of the outer peripheral portion of the fixed frame13, and the focus driving unit60is placed in the upper left position on the outer peripheral portion of the fixed frame13. Further, the X driving unit70and the Y driving unit for shake correction are placed in upper and lower right corner portions of the base plate14so as not to create dead spaces in the upper and lower positions of the zoom motor51on the right side of the outer peripheral portion of the fixed frame13.

Further, the FPC101for connecting the zoom driving unit50, the focus driving unit60, the shutter/diaphragm unit8, and the camera control section, and the FPC102for connecting the X driving unit70, the Y driving unit, and the camera control section are placed to extend toward the camera control section along the upper and lower positions of the outer peripheral portion of the fixed frame13. With these placement structures, the lens barrel1including the shake correction image pickup unit90can reduce a projection area in the optical axis O direction, thereby reducing the size of the lens barrel1as the image pickup apparatus.

The image pickup apparatus of the present embodiment described above is a camera unit including a retractable lens barrel that holds a plurality of lens groups that have a fixed frame member and a movable frame member rotationally driven with respect to the fixed frame member and moved forward and backward, and constitute an image pickup optical system, and an aperture control member that has an aperture through which an image pickup light flux from the image pickup optical system passes, and controls to narrow or open/close the aperture, a base member fixedly supported by the fixed frame member, and an image pickup device that is supported by base member, and converts a subject image formed by the image pickup optical system into an electric signal, wherein a predetermined lens group located on a side closer to a subject than a lens group located immediately before the image pickup device among the plurality of lens groups, or the aperture control member are held by a frame member driven forward and backward by the movable frame member, the aperture control member or the predetermined lens group is supported displaceably via a biasing member so as to be apart from the frame member in the image pickup optical axis direction of the image pickup optical system on an image side of the frame member, the base member includes a stopper member that abuts against the aperture control member or a holding frame that holds the predetermined lens group in retraction of the movable frame member, in a rotation position where the movable frame member can pick up an image, rotation of the movable frame member causes the predetermined lens group and the aperture control member to be moved together in the image pickup optical axis direction with the biasing member holding a predetermined distance therebetween, and in retraction where the movable frame member cannot pick up an image, with the aperture of the aperture control member opened, the aperture control member or the holding frame of the predetermined lens group is abutted against the stopper member with retraction of the movable frame member, the aperture control member or the predetermined lens group is displaced to the subject side with respect to the frame member against the biasing force of the biasing member, and at least a part of the predetermined lens group or the holding frame enters the aperture.

The image pickup apparatus of the present embodiment having such a configuration can suitably reduce the length of the lens barrel in the optical axis direction in the retracted state without increasing cost, thereby reducing a thickness.

In the image pickup apparatus of the present embodiment, the predetermined lens group is supported by the frame member, and the aperture control member is supported on the image side of the frame member via the biasing member.

In the image pickup apparatus of the present embodiment, the movable frame member includes a rotating frame rotationally driven with respect to the fixed frame member and moved forward and backward, and a cam frame rotationally driven by rotation of the rotating frame and moved forward and backward, is supported by the cam frame relatively movably forward and backward with rotation of the first group lens and the second group lens being controlled from the subject side to the image side, the third group lens as the predetermined lens group and the aperture control member are supported by the rotating frame, and the focusing fourth group lens driven forward and backward in the image pickup optical axis direction is supported by the fixed frame member.

In the image pickup apparatus of the present embodiment, the first group lens is constituted by one negative refractive power lens and one positive refractive power lens, the second group lens is constituted by a negative refractive power lens group and a positive refractive power lens group, the third group lens is constituted by a positive refractive power lens group and a negative refractive power lens group, and the fourth group lens is constituted by one positive refractive power lens.