JP5875804B2 - Lens barrel and imaging device - Google Patents

Description

  The present invention relates to a lens barrel and an imaging apparatus.

  In recent years, digital cameras that photograph a subject using an image sensor such as a CCD or a CMOS sensor have become widespread. There are various categories of digital cameras, from high-functional types for business use to compact popular types. In particular, a popular digital camera is required to be downsized so that it can be easily carried anywhere and anytime.

  Further, many of the popular digital cameras, as a lens barrel equipped with a zoom lens system, can be photographed in a form that extends in the optical axis direction and protrudes toward the front surface of the casing of the digital camera, A configuration in which the entire length is retractable is adopted between the retracted state in which the digital camera is shortened in the optical axis direction and stored in the housing of the digital camera. In order to reduce the size of the entire digital camera, it is necessary to reduce the size of the lens barrel.

  For this reason, in the lens barrel described in Patent Document 1, in the zoom lens system including the first group lens to the fourth group lens in order from the object side, the movement amount when the first group frame holding the first group lens extends in the optical axis direction is reduced. The size of each member in the direction along the optical axis is shortened by sharing the two members of the drive frame supported by the fixed frame and the cam frame supported by the drive frame. Thereby, the thickness of the lens barrel in the optical axis direction when retracted can be reduced.

JP 2008-185786 A

However, according to the configuration of the lens barrel disclosed in the cited document 1, the third lens group includes a first lens having a positive refractive power, a second lens having a positive refractive power, and a third lens having a negative refractive power. It is composed of three lenses. For this reason, the third lens is the only lens that corrects aberrations in the peripheral optical path away from the optical axis, and the axial light flux of the third lens group cannot be increased, resulting in an optical system with a dark F value. .

  In particular, in order to reduce the size of a digital camera, when the image sensor is made small without changing the number of pixels, it is necessary to reduce the pixel pitch. For this reason, in a downsized image sensor, the lack of sensitivity must be covered by the optical system, and thus an optical system with a bright F value is required.

  Therefore, in order to secure a sufficient lens ratio, the inventor of the present application sequentially starts from the object side with a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a fourth lens unit having a positive refractive power. It has a group lens and adopts a lens system that changes magnification from the wide-angle end (wide end) to the telephoto end (tele end) by changing the interval between each lens group. In order, a configuration is adopted in which a positive-end lens having positive refractive power, a first cemented lens component having a concave image side surface on the image side, and a second cemented lens having a concave object side surface on the object side are arranged. I examined that.

  According to this lens configuration, it is possible to reduce the curvature of each lens surface or the refractive power of each lens in the third lens group, thereby suppressing the occurrence of aberrations. In addition, the spherical aberration from the wide-angle end to the telephoto end is achieved by having the concave surface face the image side surface of the first cemented lens component and the object side surface of the second cemented lens component. Chromatic aberration and Petzval sum can be corrected well. In addition, it is advantageous for securing brightness, a field angle, and a zoom ratio.

  However, when the third lens group is composed of five lenses as described above, the thickness of the lens barrel in the retracted state increases due to an increase in the number of lenses housed in the lens barrel including the third lens group. Is concerned.

  Therefore, an object of the present invention made by paying attention to these points is to provide a small lens barrel and an image pickup apparatus including the same in a retracted state, in which a good aberration correction is possible in the third lens group. There is.

The invention according to the first aspect to achieve the above object is that in order from the object side to the image side, at least a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power In a lens barrel having
A fixed frame, a cam frame supported by the fixed frame and movable in the photographic optical axis direction while rotating between a front moving end and a rear moving end respectively defined in the photographic optical axis direction, and rotation restriction A guide frame that moves in the photographing optical axis direction together with the cam frame in a state; a shutter frame that moves in the photographing optical axis direction by rotation of the cam frame in a rotation restricted state; and a shutter frame that holds a shutter; A first group frame that fits on the inner periphery of the guide frame, moves in the photographing optical axis direction by rotation of the cam frame in a rotation restricted state, and holds the second group lens, and rotates in the rotation restricted state by the cam frame. When moving in the direction of the photographic optical axis and the cam frame is located at the rearward movement end, a second group frame in which at least a part of the image side is fitted on the inner peripheral side of the shutter frame and two negative lenses The three-group lens consisting of five lenses including Lifting, and a third group frame which is fixed in a state where at least a part is fitted on the object side to the inner peripheral side of the shutter frame,
Equipped with a,
Between the third group lens and the image surface, a fourth group lens having a positive refractive power is provided,
The third group lens, in order from the object side to the image side, a first lens that is a positive lens, a second lens that is a positive lens, a third lens that is a negative lens, and a fourth lens that is a negative lens; A fifth lens that is a positive lens, and the second lens and the third lens, and the fourth lens and the fifth lens each form a cemented lens,
On the image side of the third group lens, an ND filter is provided in the third group frame,
An ND filter frame that is disposed on the image side of the third group frame and holds the ND filter. The lens barrel is characterized in that at least a part of the lens surface on the image side of the five lenses enters the ND filter frame .

The invention according to a second aspect is the lens barrel according to the first aspect,
The diameter of the fourth lens is larger than the diameter of the fifth lens, the fourth lens is held by the third group frame, and the fifth lens is held by bonding to the fourth lens. To do.

The invention according to a third aspect is the lens barrel according to the first aspect,
A fourth group frame for holding the fourth group lens;
At least in a retracted state, the ND filter frame is characterized in that at least part of the ND filter frame enters the fourth group frame when viewed from a direction orthogonal to the photographing optical axis.

The invention according to a fourth aspect is the lens barrel according to the first aspect,
The ND filter frame is provided with a light aperture member.

The invention according to a fifth aspect is the lens barrel according to the first aspect,
The ND filter frame is provided with a plurality of light aperture members.

The invention according to a sixth aspect is the lens barrel according to the fifth aspect ,
One of the plurality of beam stop members is disposed in contact with the fifth lens of the third group lens.

The invention according to a seventh aspect is the lens barrel according to the fifth aspect,
The shutter frame is disposed on the object side of the third group frame, and the ND filter frame is disposed on the image side. At least one of the shutter frame and the ND filter frame is provided with a through hole in the third group frame. It is characterized by being fixed using.

The invention according to an eighth aspect is the lens barrel according to the seventh aspect ,
Either one of the shutter frame and the ND filter frame that is provided with a screw hole in the third group frame and is not fixed using the through hole is formed by using one screw that is screwed into the screw hole. It is fixed to the third group frame.

The invention according to a ninth aspect is the lens barrel according to the first aspect,
The first group frame, the second group frame, and the third group frame are directly engaged with the cam frame.

An invention according to a tenth aspect for achieving the above object is an optical device formed through the lens barrel according to the first aspect , the first group lens, the second group lens, the third group lens, and the fourth group lens. An image pickup apparatus comprising: an image pickup element that receives an image and generates image data; and an image shake correction apparatus that performs an image shake correction operation by displacing the image pickup element in a plane parallel to a light receiving surface of the image pickup element.

According to the present invention, the lens barrel includes, in order from the object side to the image side, five lenses including a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and two negative lenses. A positive-power three-group lens and a positive-power four-group lens,
When the cam frame is positioned at the rearward movement end, the second group frame that holds the second group lens is a third group frame that holds at least a part of the image side on the inner peripheral side of the shutter frame and holds the third group lens. Is fixed in a state where at least a part of the object side is fitted on the inner peripheral side of the shutter frame, so that it is possible to correct aberrations satisfactorily in the third lens group and to reduce the size in the retracted state. be able to.

It is a disassembled perspective view which shows the structure of the principal part of the imaging unit containing the lens-barrel and sensor unit which comprise the imaging device which concerns on one embodiment of this invention. It is sectional drawing in the retracted state of the imaging unit shown in FIG. It is sectional drawing in the wide position of the imaging unit shown in FIG. It is sectional drawing in the tele position of the imaging unit shown in FIG. It is a disassembled perspective view of the shutter / third group unit of FIG. It is a perspective view which shows the modification of the assembly form of a shutter / third group unit. FIG. 7 is an exploded perspective view of a third group frame and an ND filter frame portion of FIG. 6. It is a perspective view which shows the other modification of the assembly form of a shutter / third group unit. It is a figure which shows the shutter / 3 group unit seen from the image side with arrangement | positioning of ND filter. It is a figure which shows the relationship between the light ray which passes through the inside of an imaging device, and an aperture_diaphragm | restriction. 3 is an enlarged cross-sectional view of a shutter / third group unit 8. FIG. FIG. 2 is a lens cross-sectional view at a wide end (a), an intermediate state (b), and a tele end (c) of the imaging unit shown in FIG. 1. It is a rear view of the imaging unit shown in FIG.

  Hereinafter, an imaging apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  In the description of the present embodiment, the optical axis (imaging optical axis) of the imaging optical system in the lens barrel is represented by the symbol O. In the direction along the optical axis O (photographing optical axis direction), the subject side (object side) is defined as the front, and the direction in which each frame member in the lens barrel is directed forward is referred to as the feeding direction. On the other hand, in the direction along the optical axis O, the imaging side (image side) is the rear, and the direction in which each frame member heads backward is referred to as the retraction direction. Moreover, the rotation direction of each structural member in a lens barrel shall be represented by the rotation direction seen from the front side.

  The imaging apparatus according to the present embodiment uses a telescopic optical system, that is, a lens barrel. This lens barrel extends in a direction along the optical axis O, extends toward the front of the housing of the image pickup apparatus, and protrudes to perform a shooting operation, that is, in a use state in a mode waiting for the shooting operation. There are a shooting standby state (shooting enabled state) and a non-use state in which the lens barrel is not used for the shooting operation because it is stored in the housing of the imaging device by being shortened from the state of extending in the direction along the optical axis O. When the entire length of the lens barrel can be extended and retracted between the retracted state and it is in a shootable state, a plurality of frames are provided between the short focus position (wide end) and the long focus position (tele end). It has a telescopic mechanism that enables a zooming operation (zooming) by extending or retracting a member.

  First, the configuration of the lens barrel will be described with reference to FIGS.

  The lens barrel 1 is fixed to the base member 101 of the sensor unit 100 and is supported by the fixed frame 2 to be driven to rotate during zooming operation or retracting operation, and advances and retreats in the direction along the optical axis O. The cam frame 5 to be driven, the float key 6 that advances and retreats in the direction along the optical axis O together with the cam frame 5 in the rotation restricted state, and the guide frame 7 that advances and retracts along the optical axis O together with the cam frame 5 in the rotation restricted state. And a first group frame 12 holding the first group lens 21 that advances and retreats in the direction along the optical axis O by rotation of the cam frame 5 in the rotation restricted state, and a forward and backward movement in the direction along the optical axis O by rotation of the cam frame 5 in the rotation restricted state. The second group frame 11 that holds the second group lens 22, the third group frame 10 that holds the third group lens 23 that moves forward and backward in the direction along the optical axis O by the rotation of the cam frame 5 in a rotation-restricted state, and the shutter are supported. Shutter/ A group unit 8, which is retractable coupled in the direction along the optical axis O to the fixed frame 2, and a fourth group frame 13 which holds the fourth group lens 24.

  In this lens barrel 1, the cam frame 5 is positioned between the retracted state and the shootable state by rotation when the cam frame 5 moves between the rear moving end and the front moving end, and the optical axis O is in the shootable state. The first lens group 21, the second lens group 22, the third lens group 23, and the fourth lens group 24 are positioned in order from the object side to the image side, and further, the zooming effect is achieved by rotating the cam frame 5 at the front moving end. Is to be executed.

  The fixed frame 2 is formed in a cylindrical shape, and a plurality of inclined cam grooves formed in a direction inclined with respect to the optical axis O on the inner periphery thereof, and a circumferential groove formed in a direction along the circumference, Are connected to each other, and a plurality of rectilinear grooves 2b and 2c formed in the optical axis direction. A zoom drive unit 17 for performing a zooming operation of the photographing optical system is provided on the outer periphery of the fixed frame 2, and a focus for performing a focusing operation of the photographing optical system is provided inside the fixed frame 2. A drive unit 18 is disposed.

  The zoom drive unit 17 includes a zoom motor 17a that is a zoom drive source, a gear train (rotation transmission mechanism) 17b that transmits the driving force of the zoom motor 17a, a position sensor (not shown) that detects the position of the cam frame 5, and A long gear 17c and the like are included. Then, the zoom motor 17a drives the zoom optical system (the first lens group 21, the second lens group 22, and the third lens group 23) that contributes to the zooming operation in the photographing optical system of the lens barrel 1 in the direction along the optical axis O. In addition to performing a zooming operation, a retracting operation for driving the lens barrel 1 from the photographing enabled state to the retracted state is also performed. The long gear 17c of the zoom drive unit 17 is disposed in the gear housing portion 2d of the fixed frame 2 so that the rotation axis is parallel to the optical axis O, and rotates while being exposed to the inner peripheral portion of the fixed frame 2. It is supported freely.

  The focus drive unit 18 includes a focus motor 18a that is a focus drive source having a motor shaft arranged in parallel to the optical axis O, a gear train (not shown) that transmits the drive force of the focus motor 18a, a feed screw 18b, a guide shaft. 18c, and a position sensor (not shown) including a photo interrupter that detects the origin position of the focusing optical system (fourth group lens 24) that contributes to the focusing operation of the photographing optical system of the lens barrel 1 and the like. . Then, the focus motor 18a drives the fourth group lens 24 in a direction along the optical axis O.

  The cam frame 5 is formed in a cylindrical shape, and is fitted in the inner peripheral portion of the fixed frame 2 in a state where the cam frame 5 can rotate and advance and retract. A plurality of cam followers 5 a that are slidably fitted into a plurality of cam grooves 2 a of the fixed frame 2 and a gear portion 5 b that meshes with the long gear 17 c of the zoom drive unit 17 are formed at the rear peripheral portion of the cam frame 5. ing.

  As described above, the cam follower 5a of the cam frame 5 is slidably fitted into the cam groove 2a of the fixed frame 2, and the gear portion 5b is engaged with the long gear 17c. Therefore, when the zoom motor 17a of the zoom drive unit 17 is driven and the long gear 17c is rotationally driven, the driving force is transmitted to the cam frame 5 via the gear portion 5b so that the cam frame 5 is rotated. It has become. When the cam frame 5 rotates in this manner, the cam follower 5a of the cam frame 5 moves along the inclined cam groove portion of the inclined cam groove 2a of the fixed frame 2, so that the cam frame 5 is in a retracted position while rotating. From the (rear moving end), it is advanced forward to the wide end (forward moving end) which is the short focal position in the photographing enabled state. When the lens barrel 1 is in a photographing enabled state, the cam frame 5 has a cam follower 5a and a cam groove during a zooming operation from the wide end that is the short focus position to the tele end that is the long focus position. The circumferential groove 2a is driven only in the rotational direction at the forward moving end without moving forward and backward in the direction along the optical axis O.

  Further, a first group cam groove 5c is formed in the outer peripheral portion of the cam frame 5 in a direction inclined with respect to the optical axis O, and two groups in the inner peripheral portion in a direction inclined with respect to the optical axis O A cam groove 5d and a third group cam groove 5e are formed.

  The float key 6 is formed in a cylindrical shape, and is fitted in the inner peripheral portion of the cam frame 5 so as to be relatively rotatable. A guide protrusion 6 a that fits into the rectilinear groove 2 b of the fixed frame 2 projects outwardly from the outer peripheral portion of the rear end of the float key 6. As a result, the float key 6 can move forward and backward in the direction along the optical axis O together with the cam frame 5 in a state in which the rotation is restricted by the fixed frame 2.

  The float key 6 is disposed so as to be fitted into the inner peripheral portion of the cam frame 5 in a state where the bayonet protrusion 6b is fitted into the outer peripheral groove 5g of the circular recess provided in the flange portion 5f of the cam frame 5. Yes. As a result, the float key 6 can be rotated relative to the cam frame 5 and is bayonet-coupled so as not to move forward and backward relative to the cam frame 5 in the direction along the optical axis O. .

  In addition, the float key 6 has a second group rectilinear groove 6c and a third group rectilinear groove 6d formed so as to penetrate the inner and outer peripheries in the direction along the optical axis O.

  Further, the guide projection 11a of the second group frame 11 is fitted in the second group straight advance groove 6c of the float key 6, and the guide projection 10b of the third group unit 10 is fitted in the third group straight advance groove 6d. Thereby, the float key 6 supports the second group frame 11 and the shutter / third group unit 8 so as to be able to advance and retreat, and restricts the rotation.

  The guide frame 7 is formed in a cylindrical shape, and has a bayonet protrusion (not shown) that fits into a coupling groove (not shown) of the cam frame 5 on the inner periphery of the rear end. In addition, a rectilinear groove 7 b in which a cam follower 12 a formed on the rear outer peripheral portion of the group frame 12 is fitted is formed in the inner peripheral portion of the guide frame 7 in a direction along the optical axis O.

  The guide frame 7 is disposed in a bayonet connection with the cam frame 5 in a state where the guide frame 7 is fitted into the inner peripheral portion of the fixed frame 2. At this time, the guide protrusion 7 a of the guide frame 7 is fitted into the rectilinear groove 2 c of the fixed frame 2. As a result, the guide frame 7 moves integrally with the cam frame 5 in the direction along the optical axis O in a state where the rotation is restricted with respect to the fixed frame 2, as with the float key 6. ing.

  The second group frame 11 is formed in a cylindrical shape and is arranged in a state of being fitted into the inner peripheral portion of the float key 6. A second group lens 22 is held at a substantially central portion of the second group frame 11, a guide projection 11a projecting outward on the outer peripheral portion, and projecting outward on the guide projection 11a. Cam follower 11b.

  The guide projection 11a is fitted into the second group straight advance groove 6c of the float key 6, and the cam follower 11b is inserted through the second group straight advance groove 6c, and the second group cam groove of the cam frame 5 provided outside thereof. 5d is slidably fitted. As a result, the second group frame 11 is driven to advance and retract by the rotation of the cam frame 5 while being restricted in rotation by the float key 6.

  The second group frame 11 is configured such that when the cam frame 5 is positioned at the rearward movement end, a part of the image side is fitted into the inner peripheral side of the shutter frame 30 together with a part of the lens on the image side. Yes.

  The first group frame 12 is formed in a cylindrical shape, and is arranged in a state of being fitted between the cam frame 5 and the guide frame 7. A first group lens 21 is held on the object side of the first group frame 12. In addition, a plurality (for example, three inward) of the inner peripheral portion of the first group frame 12 is formed at equal intervals in the inner peripheral direction so as to fit into the first group cam grooves 5c formed on the outer peripheral portion of the cam frame 5. Cam followers (not shown).

  Further, as described above, the cam follower 12 a formed on the outer peripheral portion of the rear end of the first group frame 12 is fitted into the rectilinear groove 7 b formed on the inner peripheral portion of the guide frame 7, and is formed on the inner peripheral portion of the first group frame 12. The formed cam follower is fitted into a group cam groove 5 c formed on the outer periphery of the cam frame 5. As a result, the group frame 12 is driven to advance and retract by the rotation of the cam frame 5 while being restricted in rotation by the guide frame 7.

  FIG. 5 is an exploded perspective view of the shutter / third group unit 8 of FIG. In FIG. 5, the left side is the image side and the right side is the object side. The shutter / third group unit 8 includes a shutter frame 30 that holds a shutter mechanism, a third group frame 10 that holds a third group lens 23 on the rear side of the shutter frame 30, and a neutral density filter (ND) on the rear side of the third group frame 10. And an ND filter frame 41 holding the filter 40.

  The shutter frame 30 is a substantially circular member having an opening 30a at a substantially central portion, a shutter mechanism including a shutter blade that opens and closes the central opening, a shutter actuator that rotationally drives the shutter blade, and the like (not shown). It is comprised with the form which hold | maintained.

  The third group frame 10 has a cylindrical holding portion 10 a (see FIGS. 2 to 4) that holds the third group lens 23, and the holding portion 10 a is fitted into the shutter frame 30 from behind the shutter frame 30. Thus, the shutter frame 30 is fixed. Further, the third group frame 10 is provided with a plurality of (for example, three) guide protrusions 10b outwardly at equal intervals in the outer peripheral direction on the front outer periphery, and the guide protrusions 10b further include Cam followers 10c are provided so as to project outward.

  Moreover, as shown in FIGS. 1-4, the 3rd group frame 10 is arrange | positioned in the state inserted by the inside of the float key 6, and the guide protrusion part 10b is inserted by 6d of 3rd group straight advance groove | channels of the float key 6, The cam follower 10 c is inserted into the third group cam groove 5 e of the cam frame 5. Accordingly, the third group rectilinear frame 30 is driven to advance and retract by the cam frame 5 in a state in which the rotation is restricted by the float key 6.

  A coil spring 35 is disposed between the second group frame 11 and the shutter / third group unit 8 as shown in FIGS. As a result, the second group frame 11 and the shutter / third group unit 8 are biased in a direction away from each other. The coil spring 35 is inserted so that one end thereof is fitted to the inner peripheral portion of the shutter frame 30 of the shutter / third group unit 8, and the other end is fitted to the outer peripheral portion of the lens holder portion of the second group frame 11. Has been inserted.

  Further, as described above, the neutral density filter (ND filter) 40 is attached to the image side of the third lens group 23. This configuration is advantageous in that the arrangement of the device is easy because the shutter and the ND filter 40 do not concentrate in a narrow area, compared to the case where the ND filter 40 is arranged in the shutter frame 30. Further, as will be described later, a diaphragm member that restricts peripheral light rays is provided in the ND filter frame 41 behind the third group lens 23. In addition, by disposing the ND filter 40 on the image side of the third group lens 23 close to the shutter frame 30, it is possible to use a smaller ND filter 40 as compared with the case where it is disposed in other portions.

  A screw hole 30 b is cut in the direction along the optical axis on the image side near the outer periphery of the shutter frame 30. Further, at positions corresponding to the screw holes 30b of the third group frame 10 and the ND filter frame 41, through holes 10d and through holes 41b that are not screwed are cut. As shown in FIG. 5, the ND filter frame 41 and the third group frame 10 are screwed into the screw holes 30b of the shutter frame 30 through the screws 42 through the through holes 41b and the through holes 10d. Thus, the shutter / third group unit 8 is fixed so that the third group frame 10 is sandwiched between the shutter frame 30 and the ND filter frame 41. At this time, since the torsional stress due to screwing is not applied to the third group frame 10, undesired distortion or deflection does not occur in the third group lens.

  In addition, in the fixed state as described above, as shown in FIGS. 2 to 4, when viewed from the direction orthogonal to the photographing optical axis, the image of the fifth lens that is cemented and held by the fourth lens in the third lens group 23. At least a part of the lens surface on the side enters the ND filter frame 41. As a result, the space occupied by the third group frame 10 and the ND filter frame 41 can be reduced. Further, as shown in FIG. 2, in the retracted state, the ND filter frame 41 is configured such that at least a part of the ND filter frame 41 enters the fourth group frame 24 when viewed from a direction orthogonal to the photographing optical axis. Thereby, the lens barrel 1 in the retracted state can be further reduced in size in the optical axis direction.

  FIG. 6 is a perspective view showing a modified example of the assembled form of the shutter / third group unit 8. In this figure, the shutter / third group unit 8 is a screw hole of the shutter frame 30 through a screw 42a through a through hole 10f provided in the third group frame 10 in a state where the third group frame 10 and the ND filter frame 41 are assembled. Assemble by screwing to 30b. Here, the ND filter frame 41 has a shape having a notch so as not to interfere when the screw 42a is passed through the through hole 10f from the image side.

  FIG. 7 is an exploded perspective view of the third group frame 10 and the ND filter frame 41 in FIG. In FIG. 7, the left side is the object side, and the right side is the image side. The ND filter frame 41 is provided with a screw hole 41b, and the third group frame 10 is provided with a through hole 10e that is not screwed. The third group frame 10 and the ND filter frame are fixed by screwing the screws 42 from the object side to the screw holes 41 through the through holes 10e. In this case, when the shutter / third group unit 8 connects the third group frame 10, the shutter frame 30, and the ND filter frame 41, screw holes for screwing are provided only in the shutter frame 30 and the ND filter frame. . At this time, similarly to the assembled form of FIG. 5, the third group frame 10 is not subjected to torsional stress due to screwing, and therefore, undesired distortion or deflection does not occur in the third group lens 23.

  In the assembled form shown in FIGS. 5, 6, and 7, each is screwed at one place, but the shutter frame 30, the third group frame 10, and the ND filter frame 41 are each provided with a plurality of through holes or screw holes. It may be provided and screwed with a plurality of screws.

  FIG. 8 is a perspective view showing another modified example of the assembled form of the shutter / third group unit 8. A screw hole 30 c is cut in the direction along the optical axis on the image side near the outer periphery of the shutter frame 30. Further, a through hole 10g that is not screwed is cut at a position corresponding to the screw hole 30c of the third group frame 10. As shown in FIG. 8, in the third group frame 10, screws 42c are screwed into the screw holes 30c of the shutter frame 30 through the through holes 10g. As a result, the third group frame 10 and the shutter frame 30 are fixed. On the other hand, the third group frame 10 is provided with a screw hole 10h in addition to the through hole 10g. A through hole 41 c is provided at a position corresponding to the screw hole 10 h of the ND filter frame 41. The ND filter frame 41 is screwed to the screw hole 10h of the third group frame 10 at one location through the through hole 41c. By doing in this way, since the torsional stress by screwing is not applied between the third group frame 10 and the shutter frame 30, it is possible to prevent the third group lens 23 from being undesirably distorted or bent. On the other hand, with the ND filter frame 41, the torsional stress due to the screwing applied to the third group frame is limited to only one place by screwing at one place. Therefore, it is possible to minimize the occurrence of undesired distortion and deflection in the third group lens. Further, the fixing method of the third group frame, the shutter frame, and the ND filter frame may be as follows. That is, the third group frame may be screwed to the screw hole of the ND filter frame through the through hole, and the shutter frame may be screwed to the screw hole of the third group frame at one place through the through hole.

  FIG. 9 is a view showing the shutter / third group unit 8 together with the arrangement of the ND filter 40 as viewed from the image side. The ND filter 40 is configured to be driven back and forth between a use state and a retracted state by an electromagnetic drive mechanism (not shown) provided on the ND filter frame 41. Specifically, the ND filter 40 is moved by rotating the holder 43 that holds the ND filter 40 around the rotation shaft 44. In FIG. 9, 40 and 43 indicate the ND filter and holder in use, and 40 'and 43' indicate the retracted ND filter and holder, respectively. In FIG. 9, the holder 43 has a shape in which a portion 43 a is cut away so that vignetting of the light beam passing through the opening 41 a does not occur in the retracted state.

  10A and 10B are diagrams for explaining each aperture of the imaging apparatus 1. FIG. 10A is a diagram illustrating a relationship between a light beam passing through the imaging apparatus and a diaphragm, and FIG. 10B is an enlarged cross-sectional view of the shutter / third group unit 8. In FIG. 10A, the ND filter 40 is omitted. As shown in FIGS. 10A and 10B, the imaging apparatus 1 includes a brightness stop (aperture stop) 31 provided in front of the third lens group 10 of the shutter frame 30 and a light stop member provided in the ND filter frame 41. A flare stop A45 and a flare stop B46 are provided. The brightness stop 31 is a stop for limiting the light beam on the axis. The flare stop A45 is a stop that restricts the surrounding light rays. The flare stop A45 is configured by an edge portion of the image side end portion of the opening 41a of the ND filter frame 41. By narrowing the light beam by the flare stop A45 before the ND filter 40, the ND filter 40 can be reduced in size and can be arranged in a small space. Originally, the luminous flux is smaller at the position of the aperture stop 31 in front of the third lens group 23 than at the rear of the third lens group 23. In the present application, as shown in FIG. 10A, the flare stop A45 behind the third group lens 23 restricts a part of the peripheral rays within a range not restricting the axial rays. As a result, the flare stop A45 has the effect of improving the image quality performance at the periphery of the formed image and reducing the light flux behind the third lens group 23. For this reason, it is possible to prevent the entire diameter of the lens barrel 1 from increasing.

  Further, a flare stop B46, which is another beam stop member, is disposed on the object side surface of the ND filter frame 41. The flare stop B46 is a sheet-like member, and has a circular opening narrower than the object side end of the opening 41a of the ND filter frame 41. The flare stop B46 does not limit the effective light rays, and suppresses the occurrence of the flare or ghost caused by the incident reflected light entering the imaging element in the lens barrel 1, particularly in the cemented lens portion or the third group frame 10. It is an aperture to do.

  In addition, the flare stop B46 is disposed and held in contact with the image-side surface of the fifth lens of the third lens group 23. By doing so, it is possible to eliminate the gap between the flare stop B46 and the third lens group 23, thereby suppressing flare, ghost, etc. more efficiently.

  The fourth group frame 13 is a substantially disk-shaped frame member having a circular opening at the center for holding the fourth group lens 24. The fourth group frame 13 is coupled to the fixed frame 2 via the LD main body 19 which is a member for fixing the focus drive unit 18 attached to the rear end portion of the fixed frame 2, and the optical axis is formed inside the fixed frame 2. Supported to be movable in the direction. Further, a feed screw 18b screwed to the guide shaft 18c of the focus drive unit 18 is attached to the fourth group frame in a state where the rotation is restricted. The LD main body 19 is connected to an FPC board 117 including a drive signal line to the focus driving focus motor 18a and an origin position detection signal line to the control circuit of the imaging apparatus.

  Thereby, when the feed screw 18b is rotated via the gear train (not shown) by the driving force of the focus motor 18a of the focus drive unit 18, the fourth group frame 13 is in a direction along the guide shaft 18c, that is, It is driven back and forth in the direction along the optical axis O, and is positioned at an appropriate focusing position when it is in a photographing enabled state, and at a predetermined retracted position during a collapsing operation.

  Next, the lens configuration of the photographing optical system will be described.

  11 is a lens cross-sectional view of the imaging unit shown in FIG. 1 at the wide end (a), the intermediate state (b), and the tele end (c). As described above, the imaging apparatus according to the present embodiment includes the first group lens 21, the second group lens 22, the third group lens 23, and the fourth group lens 24 in order from the object side as a photographing optical system. Here, the first group lens 21 has a positive refractive power, the second group lens 22 has a negative refractive power, and the third group lens 23 and the fourth group lens 24 each have a positive refractive power. In FIG. 11, S, F, and C respectively indicate the aperture stop, the low-pass filter 118 that has been subjected to infrared cut coating, and the transparent cover member that is positioned in front of the imaging surface of the imaging device.

  As shown in detail in FIG. 11, for example, the lenses of each group are configured as follows. The first lens group 21 having a positive refractive power includes, in order from the object side, a negative meniscus lens 21a having a convex surface facing the object side and a cemented lens of a positive meniscus lens 21b having a convex surface facing the object side. The second group lens 22 having negative refractive power includes, in order from the object side, a negative meniscus lens 22a having a convex surface directed toward the object side, a biconcave negative lens 22b, and a biconvex positive lens 22c. The third lens unit 23 having positive refractive power includes, in order from the object side, a biconvex positive lens (first lens) 23a, a positive meniscus lens (second lens) 23b having a convex surface facing the object side, and a convex surface facing the object side. Is composed of a cemented lens with a negative meniscus lens (third lens) 23c facing and a cemented lens with a biconcave negative lens (fourth lens) 23d and a biconvex positive lens (fifth lens) 23e. Further, the fourth group lens 24 having a positive refractive power includes a positive meniscus lens 24a having a convex surface directed toward the object side.

  The aspherical surfaces include both sides of the biconcave negative lens 22b of the second group lens 22, both sides of the object side biconvex positive lens 23a of the third group lens 23, and the image side surface of the image side biconvex positive lens 23c. It is used for six surfaces on the object side of the positive meniscus lens 24a with the convex surface facing the object side of the group lens 24.

  When zooming from the wide end, which is the short focal position, to the tele end, which is the long focal position, the first lens group 21 first moves to the image side and reverses the direction of movement between the wide end and the intermediate focal length state. Move to the object side. The first group lens 21 is located closer to the object side at the tele end than at the wide end. The second group lens 22 first moves to the image side, and moves to the object side by inverting the moving direction between the telephoto end from the intermediate focal length state. The second group lens 22 is positioned closer to the image side at the tele end than at the wide end. The third group lens 23 moves only to the object side. The fourth group lens 24 first moves to the object side, and moves to the image side by reversing the moving direction from the intermediate focal length state to the telephoto end. The fourth group lens 24 is located closer to the object side at the tele end than at the wide end.

  These lens configurations are examples, and the first group lens 21 has a positive refractive power, the second group lens 22 has a negative refractive power, the third group lens 23 has a positive refractive power, and the fourth group lens 24 has a positive refractive power. Various lens configurations are possible. Therefore, for example, the second group lens 22 may be composed of two lenses, a second group object side lens and a second group image side lens. Moreover, it is good also as an achromatic lens structure which bonded the negative lens to the positive 4 group lens 24. FIG. Furthermore, a single negative lens between the positive third lens group and the positive fourth lens group (concave toward the image side, and the lens surface curvature radius is smaller than the object side lens curvature radius). The negative lens and the fourth group lens may be moved independently in the optical axis direction.

  The lens barrel 1 that holds the above-described photographic optical system is positioned and fixed to the base member 101 of the sensor unit 100 with the fixing frame 2 sandwiching the LD main body 19 therebetween. Thereby, an imaging unit in which the lens barrel 1 and the sensor unit 100 are combined is formed.

  Next, the configuration of the sensor unit 100 will be described with reference to FIG.

  The sensor unit 100 is a unit having an image blur correction device, and includes a base member 101, Y guide shafts 109 and 111 supported by the base member 101 extending in the Y direction (first direction), and a Y feed screw. 112 and an X feed screw 113 extending and supported in the X direction (second direction), a slider 114 supported by the Y guide shaft 111 and the Y feed screw 112 so as to be movable in the Y direction, and a slider 114 X guide shafts 115 and 116 which are extended and supported in the X direction, a sensor holding frame (not shown) which is supported by the X feed screw 113 and the X guide shafts 115 and 116 so as to be slidable in the X direction, An optical low-pass filter 118 (see FIGS. 2 to 4) and the image sensor 110 attached to the sensor holding frame, and a Y motor (first motor) 120 supported by the base member 101. And X motor and a (second motor) 130 (see FIG. 1).

  Note that the X direction and the Y direction are directions orthogonal to each other and orthogonal to the optical axis O, and are directions along the horizontal direction (X direction) and the vertical direction (Y direction) of the image sensor 110.

  The Y motor 120 rotates the Y feed screw 112 via the gear train 121 to drive the slider 114 in the Y direction. The X motor 130 rotates the X feed screw 113 through the gear train 131 to drive the sensor holding frame in the X direction. An FPC (not shown) connected to the base circuit board is connected to the Y motor 120 and the X motor 130 and driven. As a result, the sensor holding frame is driven along a plane parallel to the light receiving surface of the image sensor 110 by the Y motor 120 and the X motor 130, and an optical image formed on the image sensor 110 via the lens barrel 1. Image misalignment is corrected.

  Note that compression coil springs 122 and 132 are wound around the Y guide shaft 111 and the X guide shaft 116, respectively. Further, tension coil springs 123 and 133 are suspended between the base member 101, the slider 114, and the sensor holding frame. Thereby, the slider 114 and the sensor holding frame are each biased to the origin position.

  The image sensor 110 is connected to the FPC 141 and mounted on the sensor holding frame. A heat radiating plate 142 is attached to the sensor holding frame on the back side of the image sensor 110 so as to sandwich the FPC 141. For this reason, the sensor holding frame is not visible in FIG.

  Here, the base member 101 of the sensor unit 100 has a shape in which the approximate projection shape viewed from the lens barrel 1 side is a combination of a semicircle and a rectangle so that a straight portion of the semicircle and one side of the rectangle match. Have. Of the two corners of the rectangular portion, the first corner 151 includes the first drive unit 161 including the Y motor 120 and the gear train 121, and the second corner 152, which is the other corner, has an X A second drive unit 162 including a motor 130 and a gear train 131 is mounted.

  The arc of the semicircular portion extends along the outer periphery of the rear end portion of the fixed frame 2, and is on the outer side of the base member 101 on the opposite side via the second corner 152 and the optical axis O, that is, on the outer side of the fixed frame 2. A zoom drive unit 17 is arranged. The zoom motor 17a of the zoom drive unit 17 is connected to a long gear 17c in the gear housing portion 2d of the fixed frame 2 via a gear train 17b.

  A focus drive unit 18 is provided inside the fixed frame 2 at a position where it does not interfere with the optical system, and the focus motor 18a is in a state in which the motor shaft is directed forward and the rear end portion protrudes into the sensor unit 100. The LD body 19 is fixed. The rear end portion of the guide shaft 18c is held by the LD main body 19 so as to be rotatable around the shaft. Note that the focus motor 18a and the guide shaft 18c are provided with cutout portions at corresponding positions of a heat sink 142 and a slider 114, which will be described later, in the sensor unit 100, and there is a gap between the focus motor 18a and the guide shaft 18c. . That is, when the heat sink 142 and the slider 114 move in the X and Y directions, they do not come into contact with each other. The focus motor 18a and the guide shaft 18 are partially exposed when viewed from the right side in the optical axis direction in the state shown in FIG. 2 (the state shown in FIG. 6). With such a structure, the outer shape of the fixed frame is reduced in size. Accordingly, the strobe and the tripod screw can be brought closer to the fixed frame, and the image pickup apparatus can be downsized.

  The FPC 141 to which the image sensor 110 is connected extends from the image sensor 110 in the X direction on the back side of the base member 101. The FPC 141 is connected to a base circuit board so that an image captured by the image sensor 110 is displayed on a display device such as a liquid crystal panel (not shown) and recorded on a recording medium.

  Hereinafter, the operation of the imaging apparatus according to the present embodiment configured as described above will be described.

  First, when the lens barrel 1 is moved from the retracted state to the state in which the cam frame 5 is rotated clockwise and can be photographed, that is, the cam frame 5 is positioned at the forward moving end and the wide end which is the short focus position. When it becomes, as shown in FIG. 3, each frame member moves in the direction along the optical axis O toward the front, and the lens barrel 1 is in an extended state as a whole. At the wide end, the second group frame 11 and the shutter / third group unit 8 are disposed at positions separated from each other.

  When the rotating frame 3 is further rotated clockwise from the wide end at the front moving end, the first lens group 21 moves to the image side after moving to the object side, and the second lens group 22 moves to the image side. After moving to the object side, the third group lens 23 moves to the object side, and the fourth group lens 24 moves to the object side and then moves to the image side to perform a zooming operation. Then, at the telephoto end, which is the long focal position where the lens barrel 1 is extended to the maximum, as shown in FIG. 4, the second group lens 22 and the third group lens 23 are close to each other.

  Further, when the rotary frame 3 is rotated counterclockwise from the state where the lens barrel 1 is at the wide end, each frame member moves rearward along the optical axis O as the rotary frame 3 rotates. As a result, the lens barrel 1 is in the retracted state as shown in FIG. In this retracted state, a part of the second group frame 11 is fitted into the shutter frame 30, and a part on the image side of the second group lens 22 is accommodated on the inner peripheral side in the shutter frame 30. On the other hand, the guide shaft 18 c of the focus driving unit 18 is located in a space inside the fixed frame 2 and outside the shutter frame 30.

  As described above, according to the present embodiment, the third lens group 23 includes five lenses including two negative lenses, and the third lens group 10 is arranged on the inner peripheral side of the shutter frame 30. Is fixed constantly to the shutter frame 30 so that at least a part of the object side of the second group frame 22 is disposed, and in the retracted state, a part of the image side of the second group frame 22 is fitted into the shutter frame 30, and the shutter frame Since at least a part of the image side of the second group lens 22 is accommodated on the inner peripheral side of the lens 30, good aberration correction can be performed in the third group lens 23, and the lens can be made compact in the retracted state.

  In addition, since the second lens 23b and the third lens 23c of the third group lens 23 and the fourth lens 23d and the fifth lens 23e form a cemented lens in which the opposing surfaces are cemented, a third group lens. 23 can be made thinner, and the entire lens barrel 1 can be made smaller.

  Furthermore, the diameter of the fourth lens 23d of the third group lens 23 is larger than the diameter of the fifth lens 23e, the fourth lens 23d is held by the third group frame 10, and the fifth lens 23e is joined by the fourth lens 23d. Since the third group frame 10 does not protrude toward the image side with respect to the fifth lens 23e, and thus does not interfere with the ND filter 40 on the image side of the third group frame 10, the lens barrel 1 is made smaller. can do.

  In addition, since the ND filter 40 is provided on the image side of the third group lens 23 having a narrow effective light flux, the ND filter and its driving mechanism are not densely arranged in the shutter frame, and the apparatus can be easily configured. Furthermore, compared with the case where it is arranged in other parts, it is close to the shutter frame, so that a small ND filter can be used, which contributes to downsizing of the lens barrel 1. Further, since the beam stop member is provided in the ND filter frame 41, the diameter of the ND filter can be further reduced.

  Furthermore, the lens barrel 1 has a guide frame 7 that slides along the inner periphery of the fixed frame 2 from the fixed frame 2, and a group frame that slides along the guide frame 7. Since the frame 11 and the third group frame 10 are all directly engaged with the cam frame 5 and are configured to move in the optical axis direction by the rotation of the cam frame 5, smooth movement without backlash is possible.

  Further, since the second group lens 22 and the third group lens 23 approach each other at the tele position, the entire length of the lens barrel 1 can be shortened, and the imaging apparatus can be made thinner. In addition, since the coil spring 35 is interposed between the second group frame 11 and the shutter / third group unit 8 so as to be urged away from each other, the second group lens 22 is moved toward the object side in zooming operation. Even if the second lens group 22 has an inflection point that moves to the image side after moving, the second group lens 22 can be smoothly advanced and retracted.

  Note that the present invention is not limited to the above-described embodiment, and various modifications or changes can be made without departing from the spirit of the invention. For example, the lens barrel according to the present invention is not limited to a sensor unit having a CCD, but can be combined with a sensor unit having a CMOS to constitute an imaging device, or applied to a camera using a silver salt film. You can also.

  In addition, the number of lens barrel feed stages (number of stages of the lens barrel) is not limited to the two stages of the guide frame and the group frame, and may be a three-stage or four-stage configuration. For example, in the case of a three-stage lens barrel, the cam frame is extended in the optical axis direction together with the second-stage barrel from the object side, and the cam frame corresponds to each of the first group frame, the second group frame, and the third group frame. A cam groove is provided, and the first group frame, the second group frame, and the third group frame may be moved in the optical axis direction by rotation of the cam frame. Alternatively, instead of engaging all of the first group frame, second group frame, and third group frame with one cam frame, another cam frame that extends with the third stage barrel in the optical axis direction is provided, and the lens frame A part may be moved in the optical axis direction by rotation of the other cam frame.

  The diameter of the fourth lens of the third group lens is larger than the diameter of the fifth lens, the fourth lens is held by the third group frame, and the fifth lens is held by the joining with the fourth lens. As long as the thickness of the third group frame can be within a desired range, the fourth lens and the fifth lens may not be joined and held in this way.

The lens barrel of the present invention described above is the lens barrel that can achieve the object of the present invention as described below in addition to the claims.
(1) The three-group lens includes, in order from the object side to the image side, a first lens that is a biconvex positive lens, a second lens that is a positive lens having a convex surface facing the object side, and a convex surface facing the object side. A third lens that is a negative lens, a fourth lens that is a biconcave negative lens, and a fifth lens that is a biconvex positive lens, the second lens, the third lens, the fourth lens, The lens barrel according to claim 1, wherein each of the fifth lenses forms a cemented lens.

DESCRIPTION OF SYMBOLS 1 Lens barrel 2 Fixed frame 5 Cam frame 6 Float key 7 Guide frame 8 Shutter / third group unit 10 Third group frame 11 Second group frame 12 First group frame 13 Fourth group frame 17 Zoom drive unit 18 Focus drive unit 18a Focus motor 19 LD Main body 21 First group lens 22 Second group lens 23 Third group lens 24 Fourth group lens 30 Shutter frame 31 Brightness stop (aperture stop)
35 Coil spring 40 ND filter 41 ND filter frame 45, 46 Flare stop 100 Sensor unit 101 Base member 110 Image sensor 114 Slider 115 Sensor holding frame 117 FPC
119 Sensor holding frame 120 Y motor (first motor)
130 X motor (second motor)
161 First drive unit 162 Second drive unit O Optical axis

Claims (10)

In order from the object side to the image side, in a lens barrel having at least a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power,
A fixed frame, a cam frame supported by the fixed frame and movable in the photographic optical axis direction while rotating between a front moving end and a rear moving end respectively defined in the photographic optical axis direction, and rotation restriction A guide frame that moves in the photographing optical axis direction together with the cam frame in a state; a shutter frame that moves in the photographing optical axis direction by rotation of the cam frame in a rotation restricted state; and a shutter frame that holds a shutter; A first group frame that fits on the inner periphery of the guide frame, moves in the photographing optical axis direction by rotation of the cam frame in a rotation restricted state, and holds the second group lens, and rotates in the rotation restricted state by the cam frame. When moving in the direction of the photographic optical axis and the cam frame is located at the rearward movement end, a second group frame in which at least a part of the image side is fitted on the inner peripheral side of the shutter frame and two negative lenses The three-group lens consisting of five lenses including Lifting, and a third group frame which is fixed in a state where at least a part is fitted on the object side to the inner peripheral side of the shutter frame,
With
Between the third group lens and the image surface, a fourth group lens having a positive refractive power is provided,
The third group lens, in order from the object side to the image side, a first lens that is a positive lens, a second lens that is a positive lens, a third lens that is a negative lens, and a fourth lens that is a negative lens; A fifth lens that is a positive lens, and the second lens and the third lens, and the fourth lens and the fifth lens each form a cemented lens,
On the image side of the third group lens, an ND filter is provided in the third group frame,
An ND filter frame that is disposed on the image side of the third group frame and holds the ND filter, and is joined and held to a fourth lens in the third group lens when viewed from a direction orthogonal to the photographing optical axis. 5. A lens barrel characterized in that at least a part of the image side lens surface of the five lenses enters the ND filter frame.   The diameter of the fourth lens is larger than the diameter of the fifth lens, the fourth lens is held by the third group frame, and the fifth lens is held by bonding to the fourth lens. The lens barrel according to claim 1. A fourth group frame for holding the fourth group lens;
2. The lens barrel according to claim 1, wherein at least a part of the ND filter frame enters the fourth group frame when viewed from a direction orthogonal to a photographing optical axis at least in a retracted state.   The lens barrel according to claim 1, wherein a beam stop member is provided on the ND filter frame.   The lens barrel according to claim 1, wherein the ND filter frame is provided with a plurality of light aperture members.   The lens barrel according to claim 5, wherein one of the plurality of beam stop members is disposed in contact with the fifth lens of the third group lens. The shutter frame is disposed on the object side of the third group frame, and the ND filter frame is disposed on the image side. At least one of the shutter frame and the ND filter frame is provided with a through hole in the third group frame. The lens barrel according to claim 1, wherein the lens barrel is fixed using the lens barrel.   Either one of the shutter frame and the ND filter frame that is provided with a screw hole in the third group frame and is not fixed using the through hole is formed by using one screw that is screwed into the screw hole. The lens barrel according to claim 7, wherein the lens barrel is fixed to a third group frame.   The lens barrel according to claim 1, wherein the first group frame, the second group frame, and the third group frame are directly engaged with the cam frame.   The lens barrel according to claim 1, an imaging element that receives an optical image formed through the first group lens, the second group lens, the third group lens, and the fourth group lens and generates image data, and An image pickup apparatus comprising: an image blur correction device that performs an image blur correction operation by displacing the image sensor in a plane parallel to a light receiving surface of the image sensor.

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