Lens barrel

A lens barrel includes an optical imaging system having an optical axis and forming an optical image of an object. The lens barrel further includes a frame including a wall extending in the optical axis direction; an electronic component provided in the frame; and a flexible cable electrically connected to the electronic component. An opening is formed in the wall. The flexible cable covers at least a part of the opening to block a light passage through the opening.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2010-134770 filed on Jun. 14, 2010, , the entire disclosure of which is incorporated by reference herein. In addition, this application is related to Japanese Patent Publication No. 2011-128462 filed on Jun. 8, 2011, the entire disclosure of which is incorporated by reference herein.

BACKGROUND

The present disclosure relates to a lens barrel.

An imaging device such as a digital still camera etc. includes a lens barrel. The lens barrel includes an optical system, and an optical image of an object is formed on an imaging device through the optical system. In the lens barrel, when unnecessary light beams enter the imaging device, quality of an image is degraded. Thus, it is necessary to reduce the entrance of the unnecessary light beams into the imaging device.

For example, in a lens barrel of Japanese Patent Publication No. 2006-215421, a cylindrical wall extending toward an imaging device side in an optical axis direction is provided in a first group frame, thereby reducing an entrance of unnecessary light beams into the imaging device.

SUMMARY

As in the foregoing case, a cylindrical wall provided in a lens holding frame reduces reflection of unnecessary light beams inside a lens barrel. However, in a case where an electronic component such as an actuator etc. is mounted in the lens holding frame, it is necessary to provide a cable through which power is supplied to the electronic component. In such a case, it is necessary to provide an opening in a wall of the lens holding frame in order to attach the cable to the lens holding frame or improve workability of the cable attachment. If the opening is provided in the wall of the lens holding frame, unnecessary light beams may pass through the opening. As a result, there is a possibility that the unnecessary light beams enter an imaging device. In particular, if a flexible cable is used as the cable, the opening is large, and therefore the problem relating to unnecessary light beams is exacerbated.

A technique disclosed herein has been made in view of the foregoing, and it is an objective of the technique to reduce a light leakage in a configuration in which an opening for a cable attachment is provided in a frame.

The technique disclosed herein is intended for a lens barrel including an optical imaging system having an optical axis and forming an optical image of an object; a frame including a wall extending in a direction of the optical axis of the optical imaging system; an electronic component provided in the frame; and a flexible cable electrically connected to the electronic component. An opening is formed in the wall, and the flexible cable covers at least a part of the opening to block a light passage through the opening.

According to the lens barrel, the light leakage can be reduced in the configuration in which the opening for the cable attachment is provided in the frame.

DETAILED DESCRIPTION

Example embodiments will be described below in detail with reference to the drawings.FIG. 1is an exploded perspective view of a lens barrel100of the embodiments.FIG. 2is a front view of the lens barrel100.FIG. 3is an III-III cross-sectional view of the lens barrel100ofFIG. 2.

[1. Configuration of Lens Barrel100]

A lens barrel100of a first embodiment is mounted in a digital still camera. The lens barrel100includes a master flange190, various frames which will be described below, an optical imaging system formed by lenses held by the frames, and an imaging device101configured to convert light entering the imaging device101through the optical imaging system into an electrical signal and output the electrical signal. The lens barrel100is one example, and can be mounted not only in the digital still camera but also in a camcorder, a camera-equipped cell-phone, etc. The optical imaging system includes a first lens group301, a second lens group302, and a focus lens group303. The first lens group301is positioned closest to an object side. Each of the first lens group301, the second lens group302, and the focus lens group303includes one or more lenses. The optical imaging system forms an optical image of an object on an imaging surface101a of the imaging device101.

As the various frames, the lens barrel100includes a first group frame110holding the first lens group301, a second group frame120holding the second lens group302, a cam slot frame130, a translational frame140, a cam frame150, a drive frame160, a fixed frame170, and a third group frame180holding the focus lens group303. The first group frame110, the second group frame120, the cam slot frame130, the translational frame140, the cam frame150, the drive frame160, the fixed frame170, and the third group frame180are concentrically arranged about an optical axis X.

The imaging device101is fixed to the master flange190so that the imaging surface101a of the imaging device101faces the object side. In addition, the fixed frame170is fixed to the master flange190. A fixed cam groove171extending in a predetermined pattern and having a bottom, and a translational groove extending in an optical axis direction (or along a direction of the optical axis X) and having a bottom are formed in an inner circumferential surface of the fixed frame170. A zoom motor unit173is attached to the fixed frame170. In the present specification, unless otherwise described, a “groove” includes a groove having a bottom and a groove not having a bottom. In addition, unless otherwise described, a “slot” means a groove not having a bottom.

A drive cam follower161and a gear portion are provided on an outer circumferential surface of the drive frame160. The drive frame160is housed in the fixed frame170. In such a state, the drive cam follower161of the drive frame160is engaged with the fixed cam groove171of the fixed frame170, and the gear portion of the drive frame160is engaged with the zoom motor unit173. The drive frame160is rotatably driven about the optical axis by the zoom motor unit173. The drive frame160relatively moves in the optical axis direction while rotating about the optical axis with respect to the fixed frame170according to the fixed cam groove171. A circumferential groove extending in a circumferential direction and having a bottom, and a translational groove162extending in the optical axis direction and having a bottom are formed in an inner circumferential surface of the drive frame160. When a term “rotate” is simply used below, it means a rotation about the optical axis.

A first engagement protrusion133to be engaged with the translational groove of the fixed frame170, and a second engagement protrusion to be engaged with the circumferential groove of the drive frame160are provided on an outer circumferential surface of the cam slot frame130. The cam slot frame130is housed in the drive frame160. In such a state, the second engagement protrusion of the cam slot frame130is engaged with the circumferential groove of the drive frame160. This allows the cam slot frame130to relatively rotate with respect to the drive frame160, and not to relatively move in the optical axis direction with respect to the drive frame160. That is, the cam slot frame130moves together with the drive frame160in the optical axis direction. The cam slot frame130housed in the drive frame160is further housed in the fixed frame170. In such a state, the first engagement protrusion133is engaged with the translational groove of the fixed frame170. Since the translational groove of the fixed frame170extends in the optical axis direction, the cam slot frame130is supported so as to move in the optical axis direction in a state in which the cam slot frame130cannot relatively rotate with respect to the fixed frame170. A cam slot131extending in a predetermined pattern is formed in the cam slot frame130. In addition, a translational groove132extending in the optical axis direction and having a bottom is formed in an inner circumferential surface of the cam slot frame130.

Cam followers151are provided on an outer circumferential surface of the cam frame150. The cam frame150is housed in the cam slot frame130. In such a state, the cam followers151of the cam frame150penetrate the cam slot131of the cam slot frame130, and are engaged with the translational groove162of the drive frame160. In this manner, the cam frame150is held so as to rotate together with the drive frame160and translationally and relatively move in the optical axis direction with respect to the drive frame160. In addition, the cam followers151are also engaged with the cam slot131of the cam slot frame130. Thus, when the drive frame160is rotatably driven, the cam frame150relatively moves in the optical axis direction while relatively rotating with respect to the cam slot frame130according to a shape of the cam slot131. First group cam grooves152each having a bottom and second group cam grooves153each having a bottom are provided in an inner circumferential surface of the cam frame150. In addition, engagement protrusions are provided on the inner circumferential surface of the cam frame150.

The translational frame140is housed in the cam frame150. A circumferential groove extending in the circumferential direction and having a bottom is formed in an outer circumferential surface of the translational frame140. The engagement protrusions of the cam frame150are engaged with the circumferential groove. The engagement of the engagement protrusions with the circumferential groove allows the translational frame140to relatively rotate with respect to the cam frame150, and not to relatively move in the optical axis direction with respect to the cam frame150. That is, when the cam frame150moves in the optical axis direction and rotates, the translational frame140moves together with the cam frame150in the optical axis direction. The translational frame140includes engagement protrusions141outwardly protruding from a rear end portion of the translational frame140. The rear end portion of the translational frame140protrudes beyond the cam frame150, and the engagement protrusion141is engaged with the translational groove132of the cam slot frame130. The engagement of the engagement protrusion141with the translational groove132allows the translational frame140not to relatively rotate with respect to the cam slot frame130. In addition, translational slots142,143are formed in the translational frame140.

The first group frame110includes first group cam followers111. The first group frame110is housed in the translational frame140. The first group frame110is engaged with the translational slots142of the translational frame140. The first group frame110is translationally and relatively movable in the optical axis direction with respect to the translational frame140, and does not relatively rotate with respect to the translational frame140. The first group cam followers111are engaged with the first group cam grooves152of the cam frame150. When the cam frame150rotates, the first group frame110relatively moves in the optical axis direction with respect to the cam frame150and relatively rotates with respect to the cam frame150through a first cam mechanism formed by the first group cam follower111and the first group cam groove152.

The second group frame120includes second group cam followers121. The second group frame120is housed in the translational frame140. The second group frame120is engaged with the translational slot143of the translational frame140. The second group frame120is translationally and relatively movable in the optical axis direction with respect to the translational frame140, and does not relatively rotate with respect to the translational frame140. The second group cam followers121are engaged with the second group cam grooves153of the cam frame150. When the cam frame150rotates, the second group frame120relatively moves in the optical axis direction with respect to the cam frame150and relatively rotates with respect to the cam frame150through a second cam mechanism formed by the second group cam follower121and the second group cam groove153.

The third group frame180is slidably engaged with a guide pole provided in the master flange190. The third group frame180is driven separately from other frames in the optical axis direction by an actuator provided in the master flange190.

The cam groove171of the fixed frame170, the cam slot131of the cam slot frame130, and the first group cam groove152and the second group cam groove153of the cam frame150are set so as to have a proper shape corresponding to a rotational angle. Thus, the first lens group301and the second lens group302can be arranged in proper positions corresponding to a rotation amount of the drive frame160. In addition, the length of the lens barrel100in the optical axis direction when the lens barrel100is not in a shootable state (i.e., in a retracted state) can be shortened.

In the lens barrel100configured as described above, when the zoom motor unit173rotatably drives the drive frame160, the first group frame110and the second group frame120move in the optical axis direction. This adjusts a focal distance of the zoom optical system. In addition to the foregoing, the third group frame180is moved to a proper position based on a distance between the object and the lens barrel100. In such a manner, light enters the imaging device101to form an image on the imaging device101, and such an image is captured.

[2. Configuration of Second Group Frame120]

Subsequently, a configuration of the second group frame120will be described in detail.FIG. 4is a perspective view of the second group frame120to which a flexible cable400is attached.FIG. 5is a perspective view of the second group frame120as viewed from another angle.FIG. 6(A)is a plan view of the flexible cable400, andFIG. 6(B)is a bottom view of the flexible cable400.FIG. 7is a perspective view of the folded flexible cable400as viewed from the same angle as that ofFIG. 5.FIG. 8is a perspective view of the folded flexible cable400as viewed from another angle.FIG. 9is a perspective view of the second group frame120to which the flexible cable400is attached as viewed from the same angle as that ofFIG. 5.

The second group frame120is formed by molding resin such as polycarbonate etc. with a mold. The second group frame120includes a discoid portion122having an opening at the center, and a cylindrical circumferential wall123provided around the discoid portion122. A most part of the circumferential wall123extends from the discoid portion122to the object side in the optical axis direction, and the circumferential wall123also slightly extends to an imaging surface side in the optical axis direction. The circumferential wall123has a function to reduce or prevent a leakage of unnecessary light beams to an outside of the second group frame120. The second group frame120forms a frame.

In the discoid portion122, a diaphragm mechanism which is one of light amount adjusting units, a shutter mechanism which is one of the light amount adjusting units, and an OIS (optical image stabilizer) mechanism configured to reduce or prevent blurring are provided. In addition to the foregoing, in the discoid portion122, a diaphragm actuator210configured to drive the diaphragm mechanism, a shutter actuator220configured to drive the shutter mechanism, and an OIS actuator230configured to drive the OIS mechanism are further provided. The diaphragm actuator210, the shutter actuator220, and the OIS actuator230are arranged on an object-side surface of the discoid portion122inside the circumferential wall123. The diaphragm actuator210, the shutter actuator220, and the OIS actuator230form electronic components.

The diaphragm actuator210includes a motor. The diaphragm actuator210operates a turret (not shown in the figure) including a neutral density filter. The shutter actuator220includes a motor. The shutter actuator220operates a mechanical shutter (not shown in the figure). The OIS actuator230includes two pairs of a coil231and a magnet (not shown in the figure). The OIS actuator230operates an OIS lens (not shown in the figure) in two axis directions which are perpendicular to the optical axis and are perpendicular to each other.

In the second group frame120, the flexible cable400is further provided. The flexible cable400is electrically connected to each of the diaphragm actuator210, the shutter actuator220, and the OIS actuator230. The flexible cable400transmits power to each of the diaphragm actuator210, the shutter actuator220, and the OIS actuator230.

The flexible cable400has a three-layer structure in which copper foil which is a conductive layer is sandwiched between polyimide films. Specifically, the flexible cable400is configured as follows: copper foil having a thickness of about 25 μm is formed as a wiring pattern on a base film made of polyimide having a thickness of about 50 μm, and the copper foil is covered by a cover film made of polyimide having a thickness of about 50 μm. The copper foil is patterned into the wiring pattern. In the flexible cable400, a portion where the copper foil is not provided has a double-layer structure including only the polyimide films.

A first opening124and a second opening125for an attachment of the flexible cable400are formed in the circumferential wall123so that the first and second openings124,125are adjacent to each other. The first and second openings124,125are openings through the circumferential wall123in a radial direction about the optical axis X. The first opening124corresponds to an opening. The flexible cable400is pulled out from an inside of the circumferential wall123to an outside of the circumferential wall123through the first and second openings124,125. First to third support portions126-128by which the flexible cable400is fixed are provided in the circumferential wall123. Specifically, the second support portion127is provided in a portion of the circumferential wall123between the first opening124and the second opening125. The first support portion126extends in the circumferential direction from a portion of the circumferential wall123on an opposite side of the second support portion127relative to the first opening124, and covers a part of the first opening124. The third support portion128is provided in a portion of the circumferential wall123on an opposite side of the second support portion127relative to the second opening125.

The flexible cable400includes a first linear portion410, a most part of which linearly extends, a first turnback portion420which extends from an end of the first linear portion410so as to be turned back in a U-shape, a second linear portion430which extends from the first turnback portion420in parallel to the first linear portion410, a second turnback portion440which extends from an end of the second linear portion430so as to be turned back in the U-shape, a third linear portion450which is bent immediately after the turnback part in the second turnback portion440, and which linearly extends in a direction perpendicular to the second linear portion430, and first to fourth branched portions460-490which are branched from the third linear portion450. The first to fourth branched portions460-490are arranged in this order from a base end (end on the second turnback portion440side) to a tip end of the third linear portion450. The first branched portion460is branched from the third linear portion450toward the first turnback portion420, and its tip end portion is bent into a hook. The second branched portion470is branched from the third linear portion450toward the second turnback portion440. A first power supply portion471through which power is supplied to the diaphragm actuator210is provided at a tip end of the second branched portion470. The third branched portion480is branched from the third linear portion450toward the second turnback portion440. A second power supply portion481through which power is supplied to the shutter actuator220, and a third power supply portion482through which power is supplied to one of the coils231of the OIS actuator230are provided at a tip end of the third branched portion480. The fourth branched portion490is branched from the third linear portion450toward the second turnback portion440. A third power supply portion491through which power is supplied to the other coil231of the OIS actuator230is provided at a tip end of the fourth branched portion490.

An anti-reflection film is provided on a surface of the flexible cable400. Specifically, an anti-reflection film401is provided on the following portions of one of surfaces (surface illustrated inFIG. 6(A)) of the flexible cable400: a part of the first linear portion410, a part of the first turnback portion420closer to the first linear portion410, a part of the second turnback portion440closer to the third linear portion450, the third linear portion450, the first branched portion460, a base end portion of the second branched portion470, and a base end portion of the third branched portion480. On the other hand, the anti-reflection film401is provided on the following portions of the other surface (surface illustrated inFIG. 6(B)) of the flexible cable400: a part of the first turnback portion420closer to the second linear portion430, the second linear portion430, and a part of the second turnback portion440closer to the second linear portion430. The anti-reflection film401is formed of, e.g., a matte black coating.

The second turnback portion440of the flexible cable400is folded in two so that front and back portions of the second turnback portion440relative to the turn are overlapped with each other. In addition, the first branched portion460is folded in two in its base end portion so that the tip end portion of the first branched portion460is positioned on the same side as the second to fourth branched portions470-490. Further, the third linear portion450is folded in two in a position closer to the tip end of the third linear portion450than the portion where the third branched portion480is branched from the third linear portion450so that front and back portions of the third linear portion450relative to the foregoing position are overlapped with each other.

The flexible cable400folded as described above is attached to the second group frame120. Specifically, the second to fourth branched portions470-490are placed inside the circumferential wall123. The folded third linear portion450and the folded first branched portion460are positioned at the second opening125, and are sandwiched between each of the second and third support portions127,128and the circumferential wall123. The folded second turnback portion440is positioned at the first opening124, and is sandwiched between each of the first and second support portions126,127and the circumferential wall123. The second linear portion430is pulled out to the outside of the second group frame120through the first opening124, and extends toward the imaging surface side. The first linear portion410and the first turnback portion420are also positioned outside the second group frame120.

That is, the flexible cable400is pulled out from an inside of the second group frame120to the outside of the second group frame120through the first opening124. In such a state, the first opening124is covered by the second linear portion430and the second turnback portion440. In addition, the second opening125is covered by the third linear portion450and the first branched portion460.

More specifically, a portion of the folded second turnback portion440, which is closer to the second linear portion430is positioned on an outer side in the radial direction about the optical axis X relative to a portion of the second turnback portion440closer to the third linear portion450. In such a state, the anti-reflection film401provided on the second linear portion430, and the anti-reflection film401provided on the part of the second turnback portion440closer to the third linear portion450face the inside of the circumferential wall123, i.e., the actuators210-230. In addition, a base-end-side portion of the folded third linear portion450is positioned on the outer side in the radial direction about the optical axis X relative to a tip-end-side portion of the third linear portion450. In such a state, the anti-reflection film401provided on the base-end-side portion of the third linear portion450faces the inside of the circumferential wall123, i.e., the actuators210-230.

A portion of the flexible cable400, which is pulled out through the first opening124is attached to the master flange190via the translational frame140and the fixed frame170. Specifically, as illustrated inFIG. 3, the first turnback portion420is attached to the translational frame140. Subsequently, a first attachment portion411provided in the middle of the first linear portion410is attached to the fixed frame170. Then, a second attachment portion412of the first linear portion410, which is provided at an end of the first linear portion410on an opposite side of the first turnback portion420is attached to the master flange190.

[3. Advantages of the Embodiment]

The lens barrel100of the present embodiment includes the optical imaging system having the optical axis X and forming the optical image of the object; the second group frame120including the circumferential wall123extending in the optical axis direction; the diaphragm actuator210, the shutter actuator220, and the OIS actuator230provided in the second group frame120; and the flexible cable400electrically connected to the actuators210-230. The first and second openings124,125are formed in the circumferential wall123, and the flexible cable400covers at least a part of the first and second openings124,125to block the light passage through the first and second openings124,125. This allows the flexible cable400to cover a part of the first and second openings124,125even in the configuration in which the first and second openings124,125are formed in the circumferential wall123of the second group frame120, thereby reducing the light leakage through the first and second openings124,125.

The flexible cable400is pulled out from the inside of the circumferential wall123to the outside of the circumferential wall123through the first opening124. This allows the flexible cable400electrically connected to the actuators210-230to be easily pulled out to the outside of the second group frame120, thereby improving workability when the flexible cable400is attached to the second group frame120.

The anti-reflection film401is provided on at least the actuator210-230side surface of the flexible cable400in the portion of the flexible cable400, which covers the opening124. Specifically, the anti-reflection film401is provided on the actuator210-230side surface of the flexible cable400in the second turnback portion440. This allows the anti-reflection film401to absorb light from the inside of the second group frame120to the first opening124, thereby reducing generation of reflected light from the flexible cable400.

The anti-reflection film401is provided on the actuator210-230side surface of the flexible cable400in the base-end-side portion of the third linear portion450covering the second opening125. Further, the anti-reflection film401is also provided in the tip-end-side portion of the third linear portion450, which is positioned on the inner side in the radial direction about the optical axis X relative to the base-end-side portion of the third linear portion450although the surface on which the anti-reflection film401is provided faces the base-end-side portion of the third linear portion450. This allows the anti-reflection film401to absorb light from the inside of the second group frame120to the second opening125, thereby reducing the generation of reflected light from the flexible cable400.

The wiring pattern is formed in the portion of the flexible cable400, which covers the first and second openings124,125, thereby further reducing the light leakage through the first and second openings124,125by the wiring pattern.

The portion of the flexible cable400, which covers the first opening124is the second turnback portion440. Thus, in a state in which the flexible cable400extends to the object side in the optical axis direction so as to cover the first opening124and is turned back, the flexible cable400can be pulled out to the imaging surface side in the optical axis direction. This allows the flexible cable400to be pulled out to an opposite side of a direction in which the circumferential wall123extends in the optical axis direction. For example, in a state in which the flexible cable400extends in the direction in which the circumferential wall123extends from the discoid portion122so as to cover the first opening124, the flexible cable400can be pulled out to the object side in the optical axis direction. That is, depending on whether or not the second turnback portion440is provided, the flexible cable400can extend to both sides in the optical axis directions regardless of the direction in which the circumferential wall123extends. In other words, the circumferential wall123can be provided independently of the flexible cable400, thereby improving a degree of freedom of design of the circumferential wall123.

The portion of the flexible cable400, which covers the first opening124is folded at least in two. In addition, the portion of the flexible cable400, which covers the second opening125is folded at least in two (folded in four in some locations). Such folded portions further reduces the light leakage through the first and second openings124,125.

The flexible cable400is sandwiched between each of the first to third support portions126-128and the circumferential wall123at the first and second openings124,125, and the flexible cable400is not leant toward the inside of the second group frame120. As a result, a contact of the flexible cable400with the actuators210-230can be reduced or prevented.

The foregoing embodiment may have the following configurations.

In the foregoing embodiment, the flexible cable400is provided in the second group frame120, but the present disclosure is not limited to such a configuration. The similar configuration may be employed even in a case where the flexible cable400is provided in a frame other than the second group frame120.

A configuration of the lens barrel100is not limited to the foregoing configuration. For example, in the configuration of the lens barrel100, some frames may be omitted, or further frames may be added.

The circumferential wall123provided in the second group frame120is in the cylindrical shape, but the shape of the wall is not limited to such a shape. The wall provided in the second group frame120is not necessarily in a shape having a closed cross section, such as the cylindrical shape.

The electronic component electrically connected to the flexible cable400is not limited to the diaphragm actuator210, the shutter actuator220, and the OIS actuator230, but other electronic components may be electrically connected to the flexible cable400.

The flexible cable400is pulled out from the inside of the circumferential wall123to the outside of the circumferential wall123through the first opening124, but may be pulled out to the outside of the circumferential wall123through the second opening125. Alternatively, the flexible cable400may be pulled out to the outside of the circumferential wall123through both of the first and second openings124,125.

The first and second openings124,125are formed in the circumferential wall123. However, either one of such openings may be formed, or additional openings may be formed.

The flexible cable400is pulled out from the second group frame120to the imaging surface side through the first opening124, but may be pulled out to the object side.

A shape of the flexible cable400is not limited to the shape employed in the foregoing configuration. Any shapes may be employed as long as the flexible cable400is electrically connected to the actuators210-230, and the flexible cable400is pulled out to the outside of the second group frame120through the opening formed in the circumferential wall123while covering at least a part of the opening.

The flexible cable400may cover at least a part of the opening of the circumferential wall123. The anti-reflection film401is not necessarily provided on the portion of the flexible cable400, which covers the opening, and the wiring pattern is not necessarily formed in such a portion. In addition, the portion of the flexible cable400, which covers the opening is not necessarily folded in two.

The copper foil is used for the wiring in the flexible cable400, but metal foil other than the copper foil may be used.

As described above, the present disclosure is useful for the lens barrel.