Patent Description:
A lens barrel includes lens groups respectively attached to a plurality of lens frames in an optical axis direction.

For example, PTL <NUM> discloses a lens adjusting mechanism facilitating adjustment of the optical axes (eccentricity adjustment) of lenses between two lens holding members (lens frames) coupled with each other.

Further prior art can be found in <CIT> and <CIT>.

The above conventional lens barrel has a problem as described below.

The lens barrel disclosed in PTL <NUM> is capable of eccentricity adjustment between two lens holding members, but is not applicable as it is to eccentricity adjustment of inner lens frames among a plurality of lens frames.

An object of the present disclosure is to provide a lens barrel and a method for optical axis adjustment capable of facilitating eccentricity adjustment of lenses attached to inner lens frames among a plurality of lens frames disposed in the lens barrel in an optical axis direction.

A lens barrel according to the present invention as defined in claim <NUM> includes a plurality of lenses disposed in an optical axis direction, and includes a cylindrical first lens frame, a second lens frame, a third lens frame, an insertion hole, and a joint. The cylindrical first lens frame holds a first lens disposed on a subject side. The second lens frame holds a second lens disposed on a side opposite to the subject side in the first lens frame in the optical axis direction. The third lens frame is disposed between the first lens frame and the second lens frame and on an inner circumference side of the first lens frame through a radial clearance, and holds a third lens. The insertion hole is at least one through hole provided on an outer peripheral surface of the first lens frame, and a jig for eccentricity adjustment of the third lens frame is inserted into the insertion hole. The joint is provided at a position accessible from an outside in a state where the first to third lens frames are assembled, and fixes the third lens frame to the first lens frame. The joint is provided on at least one of the first lens frame and the third lens frame.

A method for optical axis adjustment according to the present invention as defined in claim <NUM> is to adjust an optical axis of a lens barrel including a first lens, a second lens, and a third lens disposed in an optical axis direction, a first lens frame having a cylindrical shape and holding the first lens, a second lens frame holding the second lens, and a third lens frame holding the third lens. The method includes a step of assembling the first to third lens frames in such a manner that the third lens frame is disposed between the first lens frame and the second lens frame and on an inner circumference side of the first lens frame through a radial clearance. The method further includes, after the assembling step, a step of inserting a jig from at least one insertion hole provided on an outer peripheral surface of the first lens frame to perform eccentricity adjustment of the third lens frame. The method further includes, after the step of the eccentricity adjustment, a step of fixing the third lens frame to the first lens frame with the joint that is provided on at least one of the first lens frame and the third lens frame and is accessible from an outside of the first lens frame in a state where the first to the third lens frames are assembled.

The lens barrel and the method for optical axis adjustment according to the present disclosure enable facilitating eccentricity adjustment of the lenses attached to inner lens frames among the plurality of lens frames in a lens barrel in which the plurality of lens frames are disposed in the optical axis direction.

An exemplary embodiment will be described below with reference to the drawings, as appropriate. A description may not be given in more detail than necessary. For example, matters that have been already well known may not be described in detail or the description of substantially the same configuration may not be repeated. This is to avoid unnecessary redundancy of the following description and facilitate the understanding of one skilled in the art.

Here, the applicant provides the attached drawings and the following description such that one skilled in the art can sufficiently understand the present disclosure, and therefore, they do not intend to restrict the subject matters of claims.

Lens barrel <NUM> according to one exemplary embodiment of the present disclosure is described below with reference to <FIG>.

Referring to <FIG>, lens barrel <NUM> according to this exemplary embodiment is a lens unit detachable from a camera body (not shown). Referring to <FIG>, lens barrel <NUM> includes six lens frames (first group lens frame unit <NUM> to fifth group lens frame unit <NUM> and lens frame <NUM>) holding an optical system including ten lenses L1 to L10 in optical axis X direction, cam frame <NUM>, fixing frame <NUM>, and aperture unit <NUM>.

Ten lenses L1 to L10 are disposed in this order from a subject side in an optical axis direction as shown in <FIG>, and guide a subject image to an image sensor (not shown) mounted on the camera body.

Referring to <FIG>, first group lens frame unit (first lens frame) <NUM> is a lens frame disposed nearest to the subject side and includes three lenses (first lenses) L1 to L3. First group lens frame unit <NUM> has body 11a, lens holding part 11b, insertion holes 11c, and openings 11d. First group lens frame unit <NUM> is moved back and forth integrally with lens frame <NUM> in optical axis X direction by operating and driving an actuator or a manual ring member (not shown).

Body 11a is a cylindrical member. Inner circumferential surface llaa of cylindrical body 11a includes lens holding part 11b, which holds three lenses L1 to L3, at an end on the subject side in the optical axis direction. Body 11a includes claws 11e on an inner circumferential surface thereof to hold lens frame <NUM> (described below) with the phase being adjusted.

Inner circumferential surface llaa includes depression (adhesive reservoir) 11ab at a position facing a depression (adhesive reservoir) 16ca disposed on an outer peripheral surface of lens frame <NUM> (described below).

Predetermined radial clearance G is provided, as shown in <FIG> and <FIG>, between inner circumferential surface llaa and outer peripheral protrusion 16c of lens frame <NUM> disposed to face inner circumferential surface 11aa.

With this configuration, lens frame <NUM> is held on the side of inner circumferential surface llaa of body 11a of first group lens frame unit <NUM> in a radially movable manner. Accordingly, radial clearance G enables eccentricity adjustment of lens L4 included in lens frame <NUM> with respect to lens group (lenses L1 to L3) included in first group lens frame unit <NUM> (described below).

Depression llab is joined with depression (adhesive reservoir) 16ca provided on the outer peripheral surface of lens frame <NUM> (described below) to form a space to be filled with adhesive <NUM> (see <FIG>).

Lens holding part 11b holds three lenses L1 to L3 in this order on the inner circumferential surface at an end of body 11a on the subject side.

Insertion hole 11c is a through hole penetrating from the outer peripheral surface to the inner circumferential surface of body 11a, and three insertion holes 11c are provided at substantially equal angular intervals (about <NUM> degrees). Jigs <NUM> for eccentricity adjustment described in the following passages (see <FIG>) are inserted in insertion holes 11c, respectively.

Since the plurality of insertion holes 11c are provided, eccentricity adjustment can be performed with high accuracy. In particular, three or more insertion holes 11c are provided, thereby further enhancing the accuracy of eccentricity adjustment in a plurality of directions orthogonal to optical axis X.

In lens barrel <NUM> according to this exemplary embodiment, insertion holes 11c are exposed outside in a state where all of the lens frames (first group lens frame unit <NUM> to fifth group lens frame unit <NUM> and lens frame <NUM>) shown in <FIG> are assembled.

Referring to <FIG> and <FIG>, three openings 11d are provided on a surface of cylindrical body 11a perpendicular to optical axis X at substantially equal angular intervals (about <NUM> degrees). Each of openings 11d exposes depressions 11ab, 16ca, to which adhesive <NUM> is applied, from the subject side of cylindrical body 11a in a state where all of the lens frames (first group lens frame unit <NUM> to fifth group lens frame unit <NUM> and lens frame <NUM>) shown in <FIG> are assembled.

Referring to <FIG>, three claws 11e are provided on the subject side of inner circumferential surface llaa of body 11a at substantially equal angular intervals (about <NUM> degrees). Each of claws 11e projects radially inwardly from inner circumferential surface 11aa. Claws 11e are engaged with outer peripheral protrusions 16c of lens frame <NUM> (described below). With this configuration, lens frame <NUM> is locked on inner circumferential surface llaa of body 11a of first group lens frame unit <NUM>.

Eccentricity adjustment of lens L4 included in lens frame <NUM> with respect to the lens group (lenses L1 to L3) included in first group lens frame unit <NUM> is detailed below.

Referring to <FIG>, second group lens frame unit (second lens frame) <NUM> is disposed on inner circumferential surface llaa side of body 11a of first group lens frame unit <NUM> in such a manner that lens frame <NUM> is sandwiched between first group lens frame unit <NUM> and second group lens frame unit (second lens frame) <NUM> in optical axis X direction. Second group lens frame unit <NUM> as shown in <FIG>, includes body 12a, lens holding part 12b, and lens L5.

Body 12a is a substantially disc-shaped member, and includes lens holding part 12b around a center opening thereof.

Lens holding part 12b has a substantially circular opening and holds lens (second lens) L5 therein.

Referring to <FIG>, lens L5 has a convex shape on the subject side, and is disposed downstream of lens L4 included in lens frame <NUM> as viewed from the subject side in optical axis X direction.

Referring to <FIG>, third group lens frame unit <NUM> is disposed on an inner circumference side of body 14a of cylindrical fourth group lens frame unit <NUM> in a movable manner in optical axis X direction. Third group lens frame unit <NUM> includes body 13a, lens holding part 13b, and lenses L6, L7. Third group lens frame unit <NUM> is moved back and forth in optical axis X direction by operating the actuator (not shown).

Body 13a is a substantially disc-shaped member and is disposed downstream of aperture unit <NUM> as viewed from the subject side in optical axis X direction (see <FIG>). Body 13a includes lens holding part 13b around a center opening thereof.

Lens holding part 13b has a substantially circular opening and holds lenses L6, L7 therein.

Lens L6 has a convex shape on the camera body (not shown) side, and is disposed downstream of aperture unit <NUM> as viewed from the subject side in optical axis X direction.

Lens L7 has a concave shape to mate with the convex shape of lens L6, and is fixed to lens holding part 13b in contact with L6,.

Fourth group lens frame unit (second lens frame) <NUM> has a substantially cylindrical shape, and is disposed downstream of third group lens frame unit <NUM> as viewed from the subject side in optical axis X direction (see <FIG>). Fourth group lens frame unit <NUM> includes body 14a, lens holding part 14b, and lenses (second lenses) L8, L9.

Body 14a is a cylindrical member. Lens holding part 14b to hold two lenses L8, L9 is provided on the inner circumference side of cylindrical body 14a.

Lens holding part 14b holds two lenses L8, L9 in this order at a position a little closer to the subject on the inner circumferential surface of body 14a.

Lens L8 is concave on both of the subject side and the camera body side.

Lens L9 is disposed downstream of lens L8, and has a convex shape to mate with the concave shape of lens L8.

Referring to <FIG>, fifth group lens frame unit <NUM> is disposed on the inner circumference side of body 14a of cylindrical fourth group lens frame unit <NUM> in a movable manner in optical axis X direction. Fifth group lens frame unit <NUM> includes body 15a, lens holding part 15b, and lens L10. Fifth group lens frame unit <NUM> is moved back and forth in optical axis X direction by operating the actuator (not shown).

Body 15a is a substantially disc-shaped member and is disposed downstream of lens L9 included in fourth group lens frame unit <NUM> as viewed from the subject side in optical axis X direction (see <FIG>). Body 15a includes lens holding part 15b around a center opening thereof.

Lens holding part 15b has a substantially circular opening and holds lens L10 therein.

Lens L10 has a convex shape on the camera body (not shown) side, and is disposed downstream of lens L9 as viewed from the subject side in optical axis X direction. Lens L10 is disposed most downstream side (camera body side) in the optical system included in lens barrel <NUM> as viewed in optical axis X direction.

Referring to <FIG>, lens frame (third lens frame) <NUM> is disposed on inner circumferential surface llaa side of body 11a of first group lens frame unit <NUM> so as to be sandwiched between the lens group included in first group lens frame unit <NUM> and second group lens frame unit <NUM> in optical axis X direction. Lens frame <NUM> includes body 16a, lens holding part 16b, outer peripheral protrusion 16c, depression (adhesive reservoir) 16ca, stopper 16d, and lens L4 (see <FIG>).

Referring to <FIG>, body 16a has a generally conical tubular shape having a generally trapezoidal shape in a sectional view, and includes lens holding part 16b around a center opening thereof. Outer peripheral protrusion 16c projecting radially outwardly is provided at an outermost part of the outer peripheral surface of body 16a.

Lens holding part 16b has a substantially circular opening and holds lens (third lens) L4 therein. Referring to <FIG> and <FIG>, lens holding part 16b is fixed to first group lens frame unit <NUM> so as to be positioned on the camera body side in optical axis X direction in a state where lens barrel <NUM> is assembled.

Lens L4 has a convex shape on the subject side as shown in <FIG>. Lens L4 is disposed downstream of lens L3 included in first group lens frame unit <NUM> as viewed from the subject side in optical axis X direction.

According to this exemplary embodiment, lens L4 has a high optical sensitivity, and requires further accuracy in the eccentricity adjustment.

Referring to <FIG>, three outer peripheral protrusions 16c, each of which is a flange-shaped member, are provided on the outer peripheral surface of body 16a on the subject side in optical axis X direction at substantially equal angular intervals (about <NUM> degrees). Depression 16ca depressed radially inwardly is provided at a substantially central part of each of outer peripheral protrusion 16c.

Depression (adhesive reservoir)16ca is disposed to face depression llab provided on inner circumferential surface llaa of body 11a of the above described first group lens frame unit <NUM> in a state where lens barrel <NUM> shown in <FIG> is assembled. A space(adhesive reservoir) to which an adhesive is applied is provided between depression 16ca and depression llab of first group lens frame unit <NUM>.

Stopper 16d projects from a surface of outer peripheral protrusion 16c perpendicular to optical axis X toward the camera body, and reinforces the strength of outer peripheral protrusion 16c. When lens frame <NUM> is fixed to the inner circumference side of first group lens frame unit <NUM>, stopper 16d positions lens frame <NUM> at the time of rotating on the inner circumference side of first group lens frame unit <NUM> (see <FIG>).

More specifically, to assemble lens barrel <NUM> according to this exemplary embodiment, lens frame <NUM> including lens L4 is firstly fixed to the inner circumference side of first group lens frame unit <NUM> (see <FIG>).

At this time, lens frame <NUM> is made contact with an innermost part of first group lens frame unit <NUM> as an initial state to secure lens frame <NUM> on the inner circumference side of first group lens frame unit <NUM> (see <FIG>).

In the state shown in <FIG>, each of three outer peripheral protrusions 16c on the outer peripheral surface of lens frame <NUM> is inserted between two of three claws 11e on first group lens frame unit <NUM> as viewed from the camera body side in optical axis X direction as shown in <FIG>.

Then, as shown in <FIG>, lens frame <NUM> is rotated counterclockwise around optical axis X with respect to first group lens frame unit <NUM> as viewed from the camera body side in optical axis X direction.

This allows three outer peripheral protrusions 16c inserted among three claws 11e to enter the subject side of claws 11e provided on first group lens frame unit <NUM> as viewed from the camera body side in optical axis X direction.

Accordingly, three outer peripheral protrusions 16c are respectively locked by three claws 11e, thereby limiting a movement of lens frame <NUM> with respect to first group lens frame unit <NUM> in optical axis X direction.

Three stoppers 16d provided on above-described lens frame <NUM> respectively come into contact with the side surfaces of claws 11e to limit the counterclockwise rotation of lens frame <NUM> on the inner circumference side of first group lens frame unit <NUM>.

With this configuration, lens frame <NUM> is locked on the inner circumference side of first group lens frame unit <NUM> so as not to fall in optical axis X direction.

At this time, lens frame <NUM> is in a provisionally fixed state on the inner circumference side of first group lens frame unit <NUM>.

In other words, movement of lens frame <NUM> with respect to first group lens frame unit <NUM> in optical axis X direction is limited through predetermined clearance d, since the engagement of claws 11e and outer peripheral protrusions 16c as described above.

Referring to <FIG>, predetermined radial clearance G is provided between each of outer peripheral protrusions 16c of lens frame <NUM> and inner circumferential surface llaa of first group lens frame unit <NUM>. Accordingly, movement of lens frame <NUM> with respect to first group lens frame unit <NUM> in a radial direction is not limited.

In the provisionally fixed state, the eccentricity of lens L4 included in lens frame <NUM> is adjusted by moving lens frame <NUM> in a radial direction while taking into consideration of the balance of all lenses L1 to L10 as a whole. In this manner, the eccentricity adjustment of lens L4 having a high optical sensitivity can be performed after assembling lens barrel <NUM> in view of the overall balance of L1 to L10, thereby enhancing the accuracy of optical axis adjustment of the lens barrel.

Referring to <FIG>, cam frame <NUM> is a cylindrical member and is disposed on the outer peripheral surface side of fourth group lens frame unit <NUM>. Cam frame <NUM> includes a cam groove (not shown) to be engaged with a cam pin (not shown) provided on the outer peripheral surface of fourth group lens frame unit <NUM>.

With this configuration, a rotation-driving power from a rotation-driving source (not shown) causes the cam pin to move along the cam groove, thereby allowing first group lens frame unit <NUM> to fifth group lens frame unit <NUM> and lens frame <NUM> to move back and forth in the optical axis direction. Accordingly, distances among lenses L1 to L10 included in first group lens frame unit <NUM> to fifth group lens frame unit <NUM> and lens frame <NUM> are adjusted, thereby enabling zoom photography, macro photography, and the like.

Referring to <FIG>, fixing frame <NUM> is a cylindrical member disposed on the outer peripheral side of first group lens frame unit <NUM> and fourth group lens frame unit <NUM> to cover the outer peripheral surfaces of first group lens frame unit <NUM> to fourth group lens frame unit <NUM>. Insertion hole 18a, which is similar to insertion hole 11c of first group lens frame unit <NUM>, is provided on fixing frame <NUM> at a position corresponding to insertion hole 11c.

Insertion hole 18a is a through hole penetrating from an outer peripheral surface to an inner circumferential surface of fixing frame <NUM>, and three insertion holes 18a are provided at substantially equal angular intervals (about <NUM> degrees) in the same manner as insertion holes 11c. Jig <NUM> (see <FIG>) for eccentricity adjustment (described below) is inserted to each of insertion hole 18a.

Aperture unit <NUM> includes a plurality of aperture blades driven by a driving source such as a stepping motor or the like (not shown). Aperture unit <NUM> opens/closes the plurality of aperture blades to change an area of an aperture, thereby changing an aperture value of the optical system of lens barrel <NUM> (lenses L1 to L10).

According to lens barrel <NUM> of this exemplary embodiment, eccentricity adjustment (optical axis adjustment) of lens frame <NUM> disposed between a plurality of lens frames is performed as described below.

A position of the optical axis of lens frame <NUM> is adjusted with jig <NUM> for eccentricity adjustment shown in <FIG> in the provisional fixed state in which lens frame <NUM> is immovable in optical axis X direction and movable in a radial direction at the inner circumference side of first group lens frame unit <NUM> as shown in <FIG>.

Specifically, jigs <NUM> for eccentricity adjustment are respectively inserted to three positions through three insertion holes 11c and three insertion holes 18a provided on the outer peripheral surface of lens barrel <NUM> at substantially equal angular intervals (about <NUM> degrees).

Insertion holes 11c, 18a are provided to communicate with the outside as described above to allow access to a part of outer peripheral side of lens frame <NUM> from the outside.

With this configuration, a radial position of lens frame <NUM> in the provisionally fixed state on the inner circumference side of first group lens frame unit <NUM> can be adjusted with tip ends of three jigs <NUM> respectively inserted in insertion holes 11c, 18a disposed at substantially equal angular intervals.

This makes it possible to align the optical axes of three lenses L1 to L3 included in first group lens frame unit <NUM> and the optical axis of lens L4 included in lens frame <NUM>.

In a state where the eccentricity is adjusted with three jigs <NUM>, adhesive <NUM> is then introduced from the subject side in optical axis X direction to fill the above described space formed by depression llab of first group lens frame unit <NUM> and depression 16ca on lens frame <NUM> as shown in <FIG>.

A UV (ultraviolet-curing resin is used as adhesive <NUM>.

Ultraviolet rays are emitted from the subject side in optical axis X direction to cure the adhesive in a state where the eccentricity is adjusted with three jigs <NUM>.

The step of filling the space formed by depression llab of first group lens frame unit <NUM> and depression 16ca on lens frame <NUM> with adhesive <NUM> and irradiating the space with ultraviolet rays may be performed one by one for three spaces disposed at substantially equal angular intervals. Alternatively, after filling all of the three spaces with adhesive <NUM>, the three spaces may be irradiated with ultraviolet rays at one time to cure the adhesive.

One exemplary embodiment of the present disclosure has been described above, but the present disclosure is not limited thereto, and various modifications may be made without departing from the scope of the present disclosure.

The above exemplary embodiment describes an example in which a lens barrel includes first group lens frame unit <NUM> to fifth group lens frame unit <NUM> including five lens groups disposed in an optical axis direction and lens frame <NUM> including lens L4. However, the present disclosure is not limited thereto.

It is only required that the lens barrel according to the present disclosure includes at least three lens frames. In the case where the lens barrel includes five lens frames for example, the configuration of the present disclosure may be applied to eccentricity adjustment of inner lens frames between the lens frames on both the sides in the optical axis direction.

The above exemplary embodiment describes an example in which a space formed by depression llab provided on inner circumferential surface llaa of body 11a of first group lens frame unit <NUM> and depression 16ca provided on outer peripheral protrusion 16c projecting radially outwardly from the outer peripheral surface of body 16a of lens frame <NUM> is used as an adhesive reservoir. However, the present disclosure is not limited thereto.

For example, either one of the depressions provided on inner circumferential surface llaa of first group lens frame unit <NUM> and on the outer peripheral surface of lens frame <NUM> may be used as an adhesive reservoir.

In other words, a depression used as an adhesive reservoir is not necessarily provided on both of inner circumferential surface llaa of first group lens frame unit <NUM> and the outer peripheral surface of lens frame <NUM>.

The above exemplary embodiment describes an example in which three claws 11e are provided on the inner circumferential surface of body 11a of first group lens frame unit <NUM> and three outer peripheral protrusions 16c are provided on the outer peripheral part of lens frame <NUM> to fix lens frame <NUM> on first group lens frame unit <NUM>. However, the present invention is not limited thereto.

For example, a number of a pair of claw 11e on the first group lens frame unit and outer peripheral protrusion 16c on lens frame <NUM> is not limited to three, and may be two or may be four or more.

Claim 1:
A lens barrel comprising:
a first lens (L1-L3), a second lens (L5, L8, L9), and a third lens (L4) disposed in an optical axis (X) direction;
a first lens frame (<NUM>) having a cylindrical shape and holding the first lens (L1-L3) disposed on a subject side;
a second lens frame (<NUM>, <NUM>) holding the second lens (L5, L8, L9); and
a third lens frame (<NUM>) disposed on an inner circumference side of the first lens frame (<NUM>) through a radial clearance (G) and between the first lens frame (<NUM>) and the second lens frame (<NUM>, <NUM>) and holding the third lens (L4),
wherein
an outer peripheral surface of the first lens frame (<NUM>) includes at least one insertion hole (11c) for inserting a jig (<NUM>) for eccentricity adjustment of the third lens frame (<NUM>), and
at least one of the first lens frame (<NUM>) and the third lens frame (<NUM>) includes a joint (11ab, 16ca) to fix the third lens frame (<NUM>) to the first lens frame (<NUM>) and at a position accessible from an outside of the first lens frame (<NUM>) in a state where the first to third lens frames (<NUM>, <NUM>, <NUM>, <NUM>) are assembled, and
characterized in that
the first lens frame (<NUM>) includes an opening (11d) different from the at least one insertion hole (11c), the opening (11d) exposes the joint (11ab, 16ca) to the outside of the first lens frame (<NUM>) from the subject side in a state where the first to third lens frames (<NUM>, <NUM>, <NUM>, <NUM>) are assembled.