Optical system and imaging apparatus

An optical system includes two imaging optical systems disposed symmetrically with each other; two holders to hold the imaging optical systems; and two shaft members including a first shaft member and a second shaft member. The first shaft member is held by the first hole of the one holder, and the second shaft member is held by the second hole of the one holder. The first shaft member is disposed in the second hole of the other holder with a movement of the first shaft member restricted in each direction perpendicular to a direction in which the first holes are opposed to the second holes. The second shaft member is disposed in the first hold of the other holder with the second shaft member movable in only a certain direction within a plane perpendicular to the direction in which the first holes are opposed to the second holes.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is based on and claims priority pursuant to 35 U.S.C. § 119(a) to Japanese Patent Application No. 2018-053348, filed on Mar. 20, 2018, in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein.

BACKGROUND

Technical Field

Embodiments of the present disclosure relate to an optical system and an imaging apparatus incorporating the optical system.

Background Art

Spherical imaging systems are known that generate an image within a solid angle of 4π steradian by combining images captured by two image sensors. Such spherical imaging systems include two imaging optical systems having the same configuration in which a wide-angle lens with a wide angle of view of 180 degrees or more and an image sensor that captures an image formed by the wide-angle lens are arranged.

Such an imaging system equipped with a plurality of optical systems as described above has the following difficulties when mounted on an imaging apparatus. First, when a plurality of optical systems is incorporated into a single lens barrel, the lens barrel tends to be of a complicated structure and be difficult to manufacture. Further, it is also difficult to incorporate optical elements constituting the optical system into the lens barrel. Further, when a plurality of optical systems is incorporated into the lens barrels each having a different structure before combining the lens barrels, such lens barrels each having a different structure and peripheral components need to be preliminarily prepared, which adversely increases the number of kinds of components, time and costs to manufacture the components. By contrast, when a plurality of optical systems is incorporated into each of the lens barrels having the same structure before mounting the lens barrels onto a base, the number of components increases and results in higher cost. What is worse is that an additional component needs to be disposed between the lens barrels, which is disadvantageous from the viewpoint of the assembly accuracy between lens barrels.

When a plurality of optical systems is combined to constitute an optical system, there are demands for proper orientations and relative positions of the optical systems to be easily set and also for sufficient strength to be obtained so as to prevent displacement of the positioned optical systems.

SUMMARY

In one aspect of this disclosure, there is provided an improved optical system including two imaging optical systems disposed symmetrically with each other; two holders including one holder to hold one imaging optical system, and other holder to hold the other one imaging optical system; and two shaft members including a first shaft member and a second shaft member. The two shaft members are disposed between the two holders. Each holder has a first hole and a second hole. The two holders are disposed such that first holes are opposed to second holes. The first shaft member is held by the first hole of the one holder, and the second shaft member is held by the second hole of the one holder. The first shaft member is disposed in the second hole of the other holder with a movement of the first shaft member restricted in each direction perpendicular to a direction in which the first holes are opposed to the second holes. The second shaft member is disposed in the first hold of the other holder with the second shaft member movable in only a certain direction within a plane perpendicular to the direction in which the first holes are opposed to the second holes.

In another aspect of this disclosure there is provided an improved imaging apparatus including the above-described optical system and two image sensors to form images captured by the two imaging optical systems, so as to combine the formed images to generate one image.

DETAILED DESCRIPTION

The present disclosure is not limited to the following embodiments, and the constituent elements of the embodiments includes those which can be easily conceived by those skilled in the art, substantially the same ones, and those in the following embodiments include those which can be easily conceived by those skilled in the art, substantially the same, and within equivalent ranges. Furthermore, various omissions, substitutions, changes and combinations of constituent elements can be made without departing from the gist of the following embodiments.

An optical system and an imaging apparatus according to embodiments of the present disclosure are described with reference to the drawings. The imaging apparatus according to the embodiments of the present disclosure includes a composite lens barrel10(FIGS. 4 to 7) incorporating an imaging system1(an optical system inFIGS. 1 to 3), and is configured by attaching, for example, an exterior member to the composite lens barrel10. The composite lens barrel10is formed by symmetrically combining a lens barrel11A and a lens barrel11B each has the same structure. First, the outline of the imaging system1is briefly described, and then the composite lens barrel10is described. As illustrated inFIG. 3, front-to-back direction is parallel to the optical axis of the front lens of the optical axis between the first lens and the third lens of a front group AF or BF. Right-to-left directions is vertical orthogonal to the front-to-back direction. As illustrated inFIG. 2, the up-to-down directions is parallel to a virtual line between the top and the bottom of a casing10.

The imaging system1includes two wide-angle lens systems (imaging optical systems) A and B arranged symmetrical to each other and two image sensors AI and BI each to form an image captured by the corresponding wide-angle lens A/B. Each set of the two wide-angle lens systems A and B and the image sensors AI and BI may have the same specification. Each of the wide-angle lens systems A and B has an angle of view greater than 180 degrees. The imaging system1may be configured as a spherical imaging system that combines two images formed by the image sensors AI and BI to obtain an image with a solid angle of47csteradian.

The wide-angle lens system A includes a negative front group AF, a first prism AP1, a variable aperture stop AS, a second prism AP2, a positive rear group AR, and a third prism AP3, which are arranged in that order from the object side to the image side. The wide-angle lens system B includes a negative front group BF, a first prism BP1, a variable aperture stop BS, a second prism BP2, a positive rear group BR, and a third prism BP3, which are arranged in that order from the object side to the image side. The front group AF/BF is capable of capturing light rays with wide angles of view of 180 degrees or more, and the rear group AR/BR is capable of correcting aberrations of an image formed by the lens system A/B. The variable aperture stop AS is illustrated inFIG. 2.

The front group AF diverges light rays of an object that have entered the front group AF from the front side (the front group AF side as illustrated inFIG. 1) while causing the diverging light rays to travel backward (to the front group BF side as illustrated inFIG. 1). The first prism AP1reflects the light rays traveling from the front group AF to the left by 90 degrees. The variable aperture stop AS adjusts the amount (amount of light) of transmission of the light reflected by the first prism APT The second prism AP2reflects the light, whose amount has been adjusted by the variable aperture stop AS, downward by 90 degrees. The rear group AR converges the light rays reflected by the second prism AP2while causing the converging light rays to travel downward. The third prism AP3reflects the light rays traveling from the rear group AR to the right by 90 degrees, and the reflected light rays forms an image on an imaging plane of the image sensor AI. Each of the front group AF and the rear group AR includes a plurality of lenses.

The front lens group BF diverges light from an object that has entered the front group BF from the back side (the front group BF side as illustrated inFIG. 1) while causing the diverging light to travel forward (to the front group AF side as illustrated inFIG. 1). The first prism BP1reflects the light traveling from the front group BF to the right (as illustrated inFIG. 2) by 90 degrees. The second prism BP2reflects the light whose amount has been adjusted by the variable aperture stop BS, downward by 90 degrees. The rear group BR converges the light reflected by the second prism BP2while causing the converging light rays to travel downward. The third prism BP3reflects the light traveling from the rear group BR to the right by 90 degrees, and the reflected light forms an image on an imaging plane of the image sensor BI. Each of the negative front group BF and the positive rear group BR includes a plurality of lenses.

The slanted surface of the first prism AP1and the slanted surface of the first prism BP1are in close contact with each other so that the first prism AP1and the first prism BP1face directions opposite to each other. In the wide-angle lens system A, the imaging plane of the image sensor AI faces the left. In the wide-angle lens system B, the imaging plane of the image sensor BI faces the right. The back faces (the opposite plane of each imaging plane) of image sensors AI and BI face in opposite directions.

In each of the wide angle lens system A and the wide angle lens system B, the optical axes of the front groups AF and BF are defined as the optical axis X1(optical axis of incident light). The optical axis of the optical path from the reflecting surface of the first prism AP1/BP1to the reflecting surface of the second prism AP2/BP2is defined as the optical axis X2. The optical axes of the rear groups AR and BR are defined as the optical axis X3. The optical axis of the optical path from the reflecting surface of the third prism AP3/BP3to the image sensor AI/BI is defined as the optical axis X4. The wide-angle lens system A and the wide-angle lens system B are arranged such that the optical axes X1are coaxially positioned and oriented in the front-to-back direction. Further, the front group AF and the front group BF are arranged to be symmetrical about a predetermined plane (a virtual plane between opposed lenses (the front lenses AF and BF of the wide-angle lens systems A and B)) perpendicular to the optical axis X1along the front-to-back direction.

The optical axes X2, X3and X4of the wide-angle lens system A and the optical axes X2, X3, and X4of the wide-angle lens system B are located within the plane between opposed lenses. More specifically, the optical axis X2of the wide-angle lens system A and the optical axis X2of the wide-angle lens system B are coaxially positioned and oriented in the right-to-left direction. Further, the optical axis X4of the wide-angle lens system A and the optical axis X4are coaxially positioned and oriented in the right-to-left direction. Further, the optical axis X3of the rear group AR and the optical axis X3of the rear group BR are spaced apart in the right-to-left direction in parallel to each other.

As described above, by bending the optical path in different directions multiple times within the plane between opposed lenses of the wide-angle lens systems A and B, a long optical path length of the wide-angle lens systems A and B can be obtained. Further, such a configuration can reduce the distance (the distance between maximum angle-of-view points) between the positions at which the light rays forming a maximum angle of view enter the lenses closest to the object side (the first lenses L1of the front groups AF and BF) in the wide-angle lens systems A and B. The distance between maximum angle-of-view points is illustrated inFIG. 1. As a result, the image sensors AI and BI can be increased in size and the imaging system1can be reduced in size. Further, the disparity that corresponds to an overlapping area of two images to be joined by calibration is reduced, thus obtaining high-quality images.

The composite lens barrel10is configured by combining a lens barrel11A supporting the wide-angle lens system A and the image sensor AI, and the lens barrel11B supporting the wide-angle lens system B and the image sensor BI. The lens barrel11A and the lens barrel11B have the same shape (structure) and are symmetrical along the front-to-back direction to be combinable. With reference to the figures followingFIG. 4, the lens barrels11A and11B are described in detail. Identical constituent elements of the lens barrel11A and the lens barrel11B are denoted by the same reference numerals. In each of the lens barrels11A and11B, the object side is the front side, and the opposite side of the object side is the back side of the front-to-back direction along the optical axis X1(of the imaging system1). The front (object side) of the lens barrel11A faces the front side and the back of the lens barrel11A faces the back side of the front-to-back direction of the imaging system1. The front (object side) of the lens barrel11B faces the back side and the back of the lens barrel11B faces the front side of the front-to-back direction of the imaging system1.

Each of the lens barrel11A and the lens barrel11B according to the embodiments of the present disclosure is an imaging unit that includes an image-forming optical system (wide-angle lens system A/B) and image sensor (AI/BI) and is capable of independently capturing an image of an object. In each of the lens barrels11A and11B, the image-forming optical system (wide-angle lens system A/B) and the members (for example, a base frame12, a front group frame13(an adhesive fixing member), a rear group frame14, a third prism frame15to be described below) directly or indirectly supporting (holding) the image-forming optical system constitute the optical system.

Each of the lens barrels11A and11B has a base frame12, a front group frame13, a rear group frame14, a third prism frame15, and an image sensor unit16. Each of the base frame12, the front group frame13, the rear group frame14, and the third prism frame15is formed as a molded product made of, for example, plastic.

In the lens barrel11A, the base frame12supports the first prism AP1, the variable aperture stop AS, and the second prism AP2. The front group frame13holds the front group AF. The rear group frame14holds the rear group AR. The third prism frame15holds the third prism AP3. The image sensor unit16is formed by combining, for example, the image sensor AI and the substrate17.

In the lens barrel11B, the base frame12supports the first prism BP1, the variable aperture stop BS, and the second prism BP2. The front group frame13holds the front group BF. The rear group frame14holds the rear group BR. The third prism frame15holds the third prism BP3. The image sensor unit16is formed by combining, for example, the image sensor BI and the substrate17.

As illustrated inFIGS. 15 to 19, the base frame12includes a front wall20, an upper wall21positioned at the upper portion of the front wall20, and side walls22and23respectively positioned at the left and right edges of the front wall20. The corner wall24is provided near the boundary of the upper wall21and the side wall22and the corner wall25is provided near the boundary of the upper wall21and the side wall23.

The front wall20has a front opening20apenetrating the front wall20in the front-to-back direction and substantially faces an object. The optical axis X1passes through substantially the center of the front opening20a. As illustrated inFIG. 15, the front wall20further has a plurality of front group frame contacts26(three in the present embodiment) positioned around the front opening20aon the front side of the front wall20. Each of the front group frame contacts26is a protrusion provided with a plane perpendicular to the optical axis X1, protruding forward in the front-to-back direction.

The front wall20further has a plurality of bonding holes27(four in the present embodiment) around the front opening20a. Each of the bonding holes27is an elongated hole whose long direction is oriented in the circumferential direction around the optical axis X1, penetrating the front wall20in the front-to-back direction. A joint face28facing forward is formed around each of the bonding holes27. A plurality of bonding recessed portions is formed on the outer edge of the front opening20a.

As illustrated inFIGS. 1 and 3, each of the front group AF and the front group BF includes a first lens L1, a second lens L3, and a third lens L3. As illustrated inFIGS. 30 and 31, the front group frame13includes an annular first lens holder13athat supports (holds) the first lens L1, an annular second lens holder13bthat holds the second lens L2, and an annular third lens holder13cthat holds the third lens L3.

As illustrated inFIGS. 30 and 31, the first lens L1held by the first lens holder13aof the front group frame13is a negative meniscus lens having a convex surface facing the object side. An annular plane L1ais formed on the periphery of a concave surface, which outputs light, of the first lens L1and is perpendicular to the optical axis X1. The first lens holder13ahas an annular lens supporting surface30on the front side, to support the plane L1a. The lens supporting surface30includes, on the back, a joint face31facing the front face (including the joint face28) of the front wall20of the base frame12and a plurality of contacts32(three in the present embodiment) positioned around the periphery of the joint face31. Each of the contacts32is a protrusion provided with a plane perpendicular to the optical axis X1, protruding backward from the joint face31in the front-to-back direction. Each of the contacts32is positioned to face the front group frame contact26of the base frame12.

A plurality of bonding holes33(four in the present embodiment) is further formed in the first lens holder13aof the front group frame13. Each of the bonding holes33is an elongated hole whose long direction is oriented in the circumferential direction around the optical axis X1, penetrating the first lens holder3ain the front-to-back direction. The lens supporting surface30side of the bonding holes33is covered with the plane L1aof the first lens L1, and the joint face31side of the bonding holes33is open.

As illustrated inFIGS. 30 to 32, each contact32of the front group frame13comes into contact with each front group frame contact26of the base frame12so that the front group frame13is positioned relative to the base frame12in the front-to-back direction. The second lens holder13band the third lens holder13chave a smaller diameter than the first lens holder13adoes and are configured to enter the front opening20a. In such a state, there is space in the radial direction about the optical axis X1between the front opening20aand the second and third lens holders13band13c, which enables the position of the front group frame13to be adjustable (optical adjustment) relative to the base frame12along the direction perpendicular to the optical axis X1. After positional adjustment, the front group frame13is bonded by adhesive to the base frame12. The following describes an adhesive structure.

As illustrated inFIG. 29, when the contact32of the front group frame13is in contact with the front group frame contact26of the base frame12and viewed from the back side of the front group frame13, four bonding holes27and bonding holes33are communicated with each other. Further, the back surface of the third lens holder13cof the front group frame13is exposed through the bonding recessed portion29. The bonding holes27, the bonding holes33, and the bonding recessed portions29are filled with adhesive, and the adhesive is cured. Thus, the front group frame13is fixed to the base frame12. For example, when the front group frame13is positioned after the positional adjustment, the bonding recessed portion29is filled with an ultraviolet curing adhesive that is then irradiated with ultraviolet rays to temporarily fix the front group frame13thereto. Subsequently, the bonding holes27and the bonding holes33are filled with adhesive having a strong adhesive force, and the final fixation is performed.

The sectional structure in the vicinity of the bonding hole27and the bonding hole33is enlarged and illustrated inFIG. 32. The bonding hole27has a narrow portion (first portion)27a, a wide portion (second portion)27b, and a width-gradual change portion (third portion)27c. The first portion27aopens toward the front side (the joint face28side). The second portion27bopens toward the back side. The third portion27cis disposed between the first portion27aand the second portion27b. The second portion27bhas longer lengths in the radial direction and circumferential direction with the optical axis X1as the center than the first portion27adoes. That is, the second portion27bhas a larger cross-sectional area than the first portion27adoes. The third portion27chas lengths in the radial direction and circumferential direction that gradually increase in a direction from the first portion27ato the second portion27b. That is, the third portion27chas a cross-sectional area that gradually increase in a direction from the first portion27ato the second portion27b. With such a configuration, when the bonding hole27is viewed in cross section along the direction of the optical axis X1as illustrated inFIG. 32, the inner surfaces of the first portion27aand the second portion27bare parallel to the optical axis X1, whereas the third portion27chas an inner surface that forms an adhesive fitting face27dof a tapered shape whose width increases toward the back side.

The bonding hole33includes a narrow portion (first portion)33a, a wide portion (second portion)33b, and a width-gradual change portion (third portion)33c. The first portion33aopens toward the back side (the joint face31side). The second portion33bopens toward the front side (the lens supporting surface30side). The third portion33cis disposed between the first portion33aand the second portion33b. The second portion33bhas longer lengths in the radial direction and circumferential direction with the optical axis X1as the center than the first portion33adoes. That is, the second portion33bhas a larger cross-sectional area than the first portion33adoes. In the width gradually changing portion33c, the width in the radial direction and the length in the circumferential direction gradually increase (the sectional area increases) gradually from the narrow portion33ato the wide portion33b. In such a configuration, when the bonding hole33is viewed in cross-section along the direction of the optical axis X1as illustrated inFIG. 32, the inner surfaces of the first portion33aand the second portion33bare parallel to the optical axis X1, whereas the third portion33chas an inner surface that forms an adhesive fitting face33dof a tapered shape whose width increases toward the front side.

Each bonding hole27is larger than a corresponding bonding hole33(communicable along the front-to-back direction). When the bonding hole27is viewed from the back side, the joint face31of the front group frame13is visually recognized around the bonding hole33(seeFIG. 29). More specifically, the first portion27aof the bonding hole27has the same width in the radial direction (the width in the vertical direction inFIG. 32) around the optical axis X1, as that of the second portion33bof the bonding hole33. The first portion33ahas the smallest width, and the second width27bhas the largest width among the portions of the bonding hole27and the bonding hole33. Further, each bonding hole27is longer in the circumferential direction around the optical axis X1than each corresponding bonding hole33(seeFIG. 29). With such a difference in size between the bonding hole27and the bonding hole33, the bonding hole33of the front group frame13is communicable with the bonding hole27of the base frame12without being blocked when the position of the front group frame13is adjusted relative to the base frame12within a predetermined range. Accordingly, adhesive can be smoothly injected (applied) from the bonding hole27side to the bonding hole33side. Further, in the configuration that bonds the bonding hole27and the bonding hole33(the bonding target is the bonding hole27and the bonding hole33), even if the amount of adjustment is greater than a predetermined value and a part of the first portion33aexceeds the range of the first portion27a, the adhesive can be applied from the bonding hole27side to the bonding hole33. With such a configuration, the amount of adjustment is more flexible than a configuration that inserts a projection into a hole to bond the projection and the hole does. As illustrated inFIG. 32, with the contact32in contact with the front frame contact26, there is a slight gap between the joint face28and the joint face31along the front-to-back direction. The bonding hole27and the bonding hole33are communicated with the gap.

As indicated by arrow TinFIG. 32, the adhesive injected from the second portion27bside of the bonding hole27flows to the bonding hole33through the third portion27cand the first portion27a. A thin sheet is sandwiched between the lens supporting surface30and the plane L1aof the first lens L1. This sheet prevents the adhesive from leaking from the bonding hole33so that the bonding hole33and the bonding hole27are filled with the adhesive. Depending on the viscosity of the adhesive, a part of the adhesive spreads to the gap between the joint face28and the joint face31. The adhesive filling in the bonding hole33and the bonding hole27is hardened to a solid state from the fluid state as time lapses or with application of energy (for example, heating), so that the base frame12and the front group frame13are fixed to each other. The adhesive U injected into the bonding hole27and bonding hole33and cured is virtually indicated by a two-dot chain line inFIG. 32.

The adhesive U is injected into both the bonding hole27and the bonding hole33, which provides a strong fixing force. With such a strong fixing force, when a load is applied in the radial direction around the optical axis X1or in the circumferential direction around the optical axis X1, relative movement between the base frame12and the front group frame13can be reliably prevented.

Further, when a load is applied in the front-to-back direction so as to separate the joint face28of the base frame12from the joint face31of the front group frame13, the cured adhesive U fit into both the bonding hole27and bonding hole33prevents the separation of the joint face28of the base frame12from the joint face31of the front group frame13. More specifically, the bonding hole27and the bonding hole33are formed such that the opening widths of the joint face28side and the joint face31side of the bonding hole27and the bonding hole33(the widths of the first portion27aand the first portion33a) facing each other are small. Further, a cross-sectional area is substantially formed such that the tip portions of two wedges facing in opposite directions are joined. Accordingly, the adhesive U injected in the bonding hole27and the bonding hole33also has the same shape as that of the cross-sectional area.

In such a configuration, when a load is applied to the front group frame13in a direction away from the base frame12(to the front side), a load in the same direction acts on the cured adhesive U through the adhesive fitting face33d. Accordingly, the adhesive U acts like a wedge against the adhesive fitting face27dthat faces the opposite direction (the back side) of the direction in which the adhesive fitting face33dfaces. This action prevents the front group frame13from separating from the base frame12. Same as in the case of the opposite direction, when a load is applied to the base frame12in a direction away from the front group frame13(to the back side), a load in the same direction acts on the cured adhesive U through the adhesive fitting face27d. Accordingly, the adhesive U acts like a wedge against the adhesive fitting face33dthat faces the opposite direction (the front side) of the direction in which the adhesive fitting face27dfaces. This action prevents the front group frame13from separating from the base frame12.

The adhesive structure according to an embodiment of the present disclosure exhibits the wedge effect using the adhesive U, the adhesive fitting face27d, and the adhesive fitting face33dof the bonding hole27and the bonding hole33that are tilted in opposite directions along the front-to-back direction. Hence, such a configuration increases the strength of adhesion between the base frame12and the front group frame13as compared to a configuration that relies on the adhesive U fixed to the first portions27aand33aand the second portions27band33bwhose inner surfaces extend along the front-to-back direction. With such a configuration that provides a superior adhesive strength between each bonding hole27and each corresponding bonding hole33, the number of bonding locations and a bonding area can be reduced so as to provide the fixation of the components. Thus, the lens barrel1A and the lens barrel11B are disposed compactly and a latitude for designing the lens barrels is increased. Particularly in the composite lens barrel10according to the embodiments of the present disclosure, the space of the front group frame13is reduced more successfully and fixed with adhesive more firmly as the first prisms AP1and BP1and the second prisms AP2and BP2are densely packed onto the back side of the base frame12to be described later.

The adhesive structure used for bonding the base frame12and the front group frame13is not limited to the above-described structure.FIGS. 33 and 34are illustrations of variations of the adhesive structure.FIG. 33is an illustration of a configuration in which the bonding hole127of the base frame12and the bonding hole133of the front group frame13have the adhesive fitting face27eand the adhesive fitting face33eof tapered shapes as a whole whose widths decrease in directions to the joint face28and the joint face31, respectively.FIG. 34is an illustration of a configuration in which the bonding hole227of the base frame12and the bonding hole233of the front group frame13has a plane adhesive fitting face27fand a plane adhesive fitting face33fperpendicular to the optical axis X1, respectively, instead of the above-described adhesive fitting face27dand adhesive fitting face33d. In these configurations ofFIGS. 33 and 34, the adhesive fitting face27eand the adhesive fitting face33eface in opposite directions and form a pair of fitting faces to fit the adhesive U, and the adhesive fitting face27fand the adhesive fitting face33fface in opposite directions and form a pair of fitting faces to fit the adhesive U. Accordingly, these configurations exhibit the same advantageous effect as that of the above-described configuration.

Alternatively, a combination of the bonding hole27(FIG. 32), the bonding hole127(FIG. 33), or the bonding hole227(FIG. 34), which is disposed on the base frame12side, and the bonding hole33(FIG. 32), the bonding hole133(FIG. 33), or the bonding hole233(FIG. 34), which are disposed on the front group frame13side, may be changed as appropriate so as to obtain a pair of fitting faces that form an asymmetrical shape in the front-to-back direction.

Any of the bonding holes27,127, and227of the base frame12and the bonding holes33,133, and233of the front group frame13has a shape easily manufactured by a mold that releases in the front-rear direction. Accordingly, the base frame12and the front group frame13can be easily obtained without an increase in manufacturing cost.

The following further describes the configuration of the base frame12. As illustrated inFIGS. 16 to 19, the upper wall21extends from the upper edge of the front wall to the back side of the composite lens barrel10, and has a top portion21a(top portions of the lens barrels11A and11B and a pair of side portions21band21cthat extend from right and left edges of the top portion21ato the down side of the composite lens barrel10. The upper wall21forms a U shape defined by the top portion21ain the upper side and the side portions21band21cin the right and left sides of the upper wall21in which the down side is open.

The side wall23and the side wall22are disposed below the upper wall21and extend from the right and left side edges to the back side of the composite lens barrel10, respectively. Each of the area that ranges from the front wall20to the side wall22and the area that ranges from the front wall20to the side wall23forms a curve shape that outlines the rear group frame14to be described later.

Each of the corner wall24and the corner wall25faces opposite directions in substantially the front-to-back direction, and is displaced to the back side relative to the front wall20. The corner wall24projects laterally from the side portion21bof the upper wall21, and the lower end of the corner wall24is connected to the upper portion of the side wall22. The corner wall25projects laterally from the side portion21cof the upper wall21, and the lower end of the corner wall25is connected to the upper portion of the side wall23. The corner wall24and the corner wall25are connected to a plurality of walls that extend in different directions, which increases the supporting strength so as to prevent deformation of the corner walls24and25.

The base frame12further includes a first prism holder35(reflective optical element holder) and a second prism holder36(reflective optical element holder) on the back surface of the front wall20. The first prism holder35serves to hold the first prism AP1or the first prism BP1on the back of the front opening20a. The second prism holder36serves to hold the second prism AP2or the second prism BP2.

The first prism holder35has an upper wall35aon the upper edge side of the front opening20aand a lower wall35bon the lower edge side of the front opening20a. On one end of the upper wall35ain the right-to-left direction, a vertical wall35cis formed to project downward. On the other end of the lower wall35bin the right-to-left direction, a vertical wall35dis formed to project upward.

The first prisms AP1and BP1are disposed between the upper wall35a, the lower wall35b, the vertical wall35c, and the vertical wall35d. There is a clearance between each of the walls35a,35b,35c,35dand the first prism AP1/BP1, and the first prism AP1/BP1is positioned using the positioning tool before bonding the first prism AP1/BP1to the first prism holder35with adhesive.

As described above, in the composite lens barrel10completely assembled, the slanted surfaces of the first prism AP1and the first prism BP1are in close contact with each other, facing opposite directions. With such an arrangement, the first prism holder35is formed to leave uncovered the back sides of the slanted surfaces of the first prism AP1and the first prism BP1so that the back sides of the slanted surfaces of the first prism AP1and the first prism BP1are exposed to the outside of the composite lens barrel10.

The second prism holder36is disposed below the side portion21bof the upper wall21and the corner wall24, and includes a support seat36afacing the back side of the composite lens barrel10and a support wall36bthat projects from the support seat36ato the back side of the composite lens barrel10. The side surfaces of the second prism AP2and BP2contact the support seat36a. The slanted surfaces of the second prism AP2and BP2contact the support wall36b. The second prisms AP2and BP2are positioned in the direction of slant using the positioning tool. Then, the positioned second prisms AP2and BP2are bonded (fixed) to the second prism holder36with adhesive.

FIG. 13is an illustration of the rear group frame14alone without the base frame12attached to. As illustrated inFIGS. 9, 13, and 14, the rear group frame14has a cylindrical portion14ahaving a substantially cylindrical shape with the optical axis X3extending in the vertical direction as the center. Further, a plurality of lenses constituting the rear group AR or BR is fixedly held within the cylindrical portion14a. The rear group frame14further includes a prism cover14bon the upper portion of the cylindrical portion14a. A support tab14cprojects laterally from the cylindrical portion14a, and a support tab14dprojects upward from the prism cover14b. A joining flange14eis formed at the lower end of the cylindrical portion14a.

As illustrated inFIGS. 16 to 19, on the back side of the base frame12, a rear group frame holder37(lens positioner) is formed below the corner wall24and the second prism holder36. The rear group frame holder37is a concave portion surrounded by the front wall and the side wall22and has a shape that enables substantially half (portion positioned on the front side) of the cylindrical portion14aof the rear group frame14to be accommodated within the rear group frame holder37. The prism cover14bcovers a part of the second prisms AP2and BP2held by the second prism holder36of the base frame12with the cylindrical portion14aaccommodated in the rear group frame holder37.

A support seat38(the lens positioner) is formed on the side of the rear group frame holder37(below the lower wall35bof the first prism holder35), and a support seat39(the lens positioner) is formed above the second prism holder36. Each of the support seat38and the support seat39has an annular plane perpendicular to the optical axis X1, and a screw hole is formed in the center of the annular plane. With the cylindrical portion14aof the rear group frame14accommodated in the rear group frame holder37, the support tab14ccontacts the support seat38, and the support tab14dcontacts the support seat39. Through-holes are formed respectively in the support tab14cand the support tab14d. The fixing screw40is screwed into the screw hole of the support seat38through the through-hole of the support tab14c, and the fixing screw41is screwed into the screw hole of the support seat39through the through-hole of the support tab14d. By tightening the fixing screw40and the fixing screw41, the rear group frame14is fixed to the base frame12with the position of the rear group frame14determined (seeFIG. 14).

On the back side of the base frame12, a rear group frame accommodating section42(a lens accommodating section) is formed below the corner wall25. The rear group frame accommodating section42is a recessed portion surrounded by the front wall20and the side wall23and has a shape that enables substantially half (portion positioned on the back side) of the cylindrical portion14aof the rear group frame14to be accommodated within the rear group frame accommodating section42. Prior to combining the lens barrel11A and the lens barrel11B, the rear group frame accommodating section42is an empty space (seeFIGS. 9 and 14). When the lens barrel11A and the lens barrel11B are combined, the rear group frame holder37of one base frame12and the rear group frame accommodating section42of the other base frame12face each other in the front-to-back direction, so as to form space to accommodate the cylindrical14aof the rear group frame14inside the combination of the lens barrel11A and the lens barrel11B.

The third prism frame15includes a prism support wall15athat supports the slanted surfaces and side surfaces of the third prisms AP3and BP3. Each of the third prisms AP3and BP3is bonded (fixed) to the third prism frame15with adhesive. On the upper portion of the third prism frame15, a joining flange15bis provided. The joining flange15bcan be fitted into the joining flange14eof the rear group frame14from below. With the joining flange15bfitted to the joining flange14e, the third prism frame15is positioned and fixed to the rear group frame14with adhesive.

The image sensor unit16is provided with a pair of fitting pieces43at the edge in the front-to-back direction. The pair of fitting pieces43are fitted into the recesses formed in the prism support wall15aof the third prism frame15, which positions the image sensor unit16relative to the third prism frame15. The image sensor unit16is fixed to the third prism frame15with adhesion. With such a state, the imaging planes of the imaging sensors AI and BI face in a direction perpendicular to the optical axis X4. Further, the imaging plane of the image sensor AI faces the exit surface of the third prism AP3, and the imaging plane of the image sensor BI faces the exit surface of the prism BP3.

The image sensor unit16includes a substrate17having image sensors AI and BI on one side. The substrate17is substantially rectangular. With the image sensor unit16bonded to the third prism frame15, the long direction of the substrate17is along the up-and-down directions, and the lateral direction of the substrate17is along the front-to-back direction of the imaging apparatus80. Further, the direction of thickness of the substrate17is along right-to-left direction. In the vicinity of the lower end of the substrate17, a connector17ato be connected to the control circuit of the imaging apparatus80is disposed. The connector17ais disposed on the side of the substrate17on which the image sensors AI and BI are provided.

By combining the above-described constituent elements, each of the lens barrel11A and the lens barrel11B is completely assembled.FIGS. 9 to 12are illustrations of the lens barrel11A and the lens barrel11B, which are separated from each other.FIGS. 13 and 14are illustrations of one of the lens barrel11A and the lens barrel11B. As can be seen from these drawings, the lens barrel11A and the lens barrel11B have the same structures.

As illustrated inFIG. 10, each of the lens barrel11A and the lens barrel11B has a size in the front-to-back direction accommodated within the width in the lateral direction (the front-to-back direction) of the substrate17, except for a portion where each of the front groups AF and BF and a part of the front group frame13are exposed to the outside of the imaging apparatus80. Each of the wide-angle lens system A and B is configured to be a folded optical system in which the optical path is bent multiple times using a plurality of prisms (the light is reflected (redirected) by a prism multiples times (a plurality of prisms are disposed to reflect the light multiple times)) within a plane (plane between the lenses closest to the object side in the wide-angle lens systems A and B) perpendicular to the optical axis X1. This configuration enables the lens barrel11A and the lens barrel11B to be thin in the front-to-back direction.

The lens barrel11A and the lens barrel11B having the same structure are combined to be together and opposed to each other along the front-to-back direction (seeFIGS. 9 and 12), which provides the composite lens barrel10in a complete state as illustrated inFIGS. 4 to 8. As illustrated inFIGS. 9 to 12, the lens barrel11A and the lens barrel11B have a structure in which the protrusions and recesses of the lens barrel11A and the lens barrel11B are combined by bringing the lens barrels11A and11B together. This configuration enables the lens barrel11A and the lens barrel11B to be coupled to each other compactly.

InFIG. 5, a virtual plane Q1and a virtual plane Q2are indicated. The virtual plane Q1includes the optical axis X1and extends along the up-to-down direction. The virtual plane Q2is perpendicular to the virtual plane Q1and passes through the lower end of the base frame12. In the lens barrel11A, the optical path from the second prism AP2to the image sensor AI after being bent by the first prism AP1passes through the left area of the virtual plane Q1. In the lens barrel11B, the optical path from the second prism BP2to the image sensor BI after being bent by the first prism BP1passes through the right area of the virtual plane Q1. As illustrated inFIGS. 11 and 12, on the left side of the virtual plane Q1, the constituent elements of the lens barrel11A project beyond the base frame12to the back side of the imaging apparatus80, whereas the constituent elements of the lens barrel11B does not project beyond the base frame12to the front side of the imaging apparatus80. Similarly, on the right side of the virtual plane Q1, the constituent elements of the lens barrel11B project beyond the base frame12to the front side of the imaging apparatus80, whereas the constituent elements of the lens barrel11A do not project beyond the base frame12to the back side of the imaging apparatus80. Thus, when the lens barrel11A and the lens barrel11B are combined, the rear group frames14, the third prism frames15, and the image sensor units16on the lens barrel11A side and the lens barrel11B side are arranged side by side symmetrically without interfering with each other.

Further, in the wide-angle lens systems A and B, light beams from the object, which have been reflected by the first prisms AP1and BP1to the left and right, respectively, are reflected by the third prisms AP3and BP3to travel in a direction to the virtual plane Q1and reach the image sensors AI and BI, respectively. For this reason, the image sensor unit16on the lens barrel11A side is close to the image sensor unit16on the lens barrel11B side along right-to-left direction. Particularly, the substrate17on the lens barrel11A side is close to the substrate17on the lens barrel11B side across the virtual plane Q1. In the central portion of each of the lens barrels11A and11B along right-to-left direction, the first prism AP1/BP1is disposed above the virtual plane Q2, and the two image sensor units16are arranged with the back surfaces opposed to each other below the virtual plane Q2. The substrates17on the lens barrel11A side and the lens barrel11B side has a planar shape substantially parallel to the virtual plane Q1. Further, there is a clearance between the substrates17on the lens barrel11A side and the lens barrel11B side in the right-to-left direction. Such a configuration prevents these substrates17from interfering with each other when the lens barrel11A is brought close to the lens barrel11B.

Since the first prism AP1and the first prism BP1are arranged such that the slanted surfaces of the first prism AP1and the first prism BP1are in close contact with each other, the thickness of the composite lens barrel10in the front-to-back direction that is substantially occupied by the two prisms AP1and BP1merely corresponds to the space for one prism although the two prisms AP1and BP1are arranged side by side in the front-to-back direction (seeFIG. 3). Further, the image sensor unit16of the lens barrel11A and the image sensor unit16of the lens barrel11B are substantially at the same position in the front-to-back direction and are arranged side by side in the right-to-left direction. Accordingly, with a space in the front-to-back direction of the composite lens barrel10sufficient to accommodate the width of one substrate17in the lateral direction, the two image sensor units16are able to be accommodated below the first prisms AP1and BP1in the composite lens barrel10. With such a configuration, the thickness of the composite lens barrel10in the front-to-back direction can be reduced for the central portion of the composite lens barrel10in the right-to-left direction in which the constituent elements (the first prisms AP1and BP1and the image sensor units16) of the lens barrels11A and11B overlap and for the vicinity of the ends of the composite lens barrel10in the right-to-left direction in each of which the constituent elements (the rear group frame14and the third prism frame15) of one of the lens barrels11A and11B are disposed.

As described above, the constituent elements of the lens barrels11A and the lens barrel11B are disposed compactly in the composite lens barrel10in the front-to-back direction, the right-to-left direction, and the up-to-down direction. Thus, a compact structure is provided while including two lens barrels11A and11B.

As described above, the lens barrel11A and the lens barrel11B are disposed symmetrically along the front-to-back direction and brought together along the front-to-back direction so as to be combined with each other. Note that the lens barrel11A and the lens barrel11B are combined with a stable relative position such that the optical systems (the wide-angle lens systems A and B) of the lens barrels11A and11B face in the proper directions. Specifically, the lens barrel11A and the lens barrel11B are positioned in the front-front-to-back direction along the optical axis X1and positioned in a direction along the plane perpendicular to the optical axis X1(the up-to-down and right-to-left directions). Further, in order to make the imaging system1including the two optical systems (wide-angle lens systems A and B) work, after combining the lens barrel11A and the lens barrel11B (more specifically, after calibration of the imaging system1including the wide-angle lens systems A and B), a high bonding strength is needed to prevent a change in the relative positions between the lens barrels11A and the lens barrel11B due to, for example, external force.

A description is given of the structure that positions the lens barrel11A and the lens barrel11B in the front-to-back direction. On the base frame12, a contact surface50is disposed on the back surface of the corner wall24, and a contact surface51is disposed on the back surface of the corner wall25. The contact surface50is formed as an end surface of a cylindrical boss52projecting forward and backward beyond the corner wall24, and the contact surface51is formed as an end surface of a cylindrical boss53projecting forward and backward beyond the corner wall25. Both the contact surface50and the contact surface51are annular planes perpendicular to the optical axis X1and have a symmetrical shape in the front-to-back direction.

In the interior of the boss52, a screw hole54whose long axis line is oriented in the front-to-back direction is formed. The screw hole54is open at the end on the back side at the contact surface50, and the opposite front end is closed. Inside the boss53, screw insertion holes55penetrating in the front-to-back direction are formed.

FIGS. 9 to 12are illustrations of the lens barrel11A and the lens barrel11B with the contact surface50and the contact surface51of the lens barrel11A facing the contact surface51and the contact surface50of the lens barrel11B, respectively. When the lens barrel11A and the lens barrel11B are brought together in the front-to-back direction with this relative position, the contacts surface50of the lens barrels11A and11B come into contact (abut) with and the contacts surface51of the lens barrels11A and11B, respectively, which determines the relative positions of the lens barrels11A and11B in the front-to-back direction. With such a contact state, the positional accuracy of the lens barrel11A and lens barrel11B of the composite lens barrel10in the front-to-back direction is controlled.

A screw is used to fix the lens barrel11A to the lens barrel11B. Specifically, a fixing screw is inserted into the screw insertion hole55of the lens barrel11A from the front and screwed into the screw hole54of the lens barrel11B. Further, a fixing screw is inserted into the screw hole54of the lens barrel11B and screwed into the screw insertion hole55of the lens barrel11B. By tightening the fixing screws, the lens barrel11A and the lens barrel11B are fixed to each other.

The base frame12of each of the lens barrels11A and11B holds (supports) a plurality of prisms (the first prism AP1, the first prism BP1, the second prism AP2, and the second prism BP2). Further, the front group frame13and the rear group frame14are attached to the base frame12. That is, all the optical elements are supported by the base frame12as a support reference. Accordingly, as the assembly accuracy of the base frame12exerts a particularly great influence on the optical performance, the base frame12is provided with the contact surfaces50and51that serve as a relative position reference in the front-to-back direction of each of the lens barrels11A and11B.

The contact surface50and the contact surface51are disposed at the right and left ends of the base frame12along the right-to-left direction. The maximum distance between the contact surface50and the contact surface51in the right-to-left direction are provided under the dimensional restriction of the base frame12. With an increase in the distance between the contact surface50and the contact surface51serving as a position reference, the two base frames12effectively are prevented from being tilted, and thus the accuracy of positioning of the lens barrels11A and11B is increased. As illustrated inFIG. 14, the contact surface50is disposed in a space on the back of the slanted surfaces of the second prisms AP2and BP2. That is, the space is efficiently utilized. The contact surface50is disposed above the rear group frame holder37that holds the rear group frame14. The contact surface51is disposed above the rear group frame accommodating section42that covers the rear group frame14from the back side. With such an arrangement, the contact surfaces50and51are disposed so as not to overlap with the positions of the rear groups AR and BR, the first prisms AP1and BP1, and the second prisms AP2and BP2, which are held by the respective base frames12on the back side. Further, the contact surface50and the contact surface51are disposed with a wide distance between the contact surface50and the contact surface51.

The corner wall24includes the contact surface50, and the corner wall25includes the contact surface51. The corner wall24and the corner wall25are connected to the plurality of walls facing different directions in the vicinity of the upper wall21and the side walls22and23. Accordingly, the corner wall24and the corner wall25have a planar shape and still high rigidity. That is, the contact surface50and the contact surface51have a high surface accuracy, which prevents the corner walls24and25from being distorted and allows for highly accurate of positioning when the contact surface50contacts the contact surface51.

Further, as illustrated inFIG. 5, the boss52having the contact surface50and the boss53having the contact surface51are disposed substantially symmetrically relative to the optical axis X1along the right-to-left direction. Such an arrangement provides a positioning accuracy equal in the front-to-back direction on the right and left sides of the optical axis X1, and is particularly advantageous in obtaining the positional accuracy of front groups AF and BF and the first prisms AP1and BP1. Further, since the contact surfaces50and51provides high positioning accuracy and stability, the lens barrel11A and the lens barrel11B are combined without interfering with each other.

For example, when the lens barrel11A is combined with the lens barrel11B, the cylindrical portion14aof the rear group frame14of a corresponding lens barrel11A/11B comes into the rear group frame accommodating section42on the back side of each base frame12, so that the cylindrical portion14a(the rear group AR/BR) is positioned between the rear group frame holder37and the rear group frame accommodating section42, which are opposed to each other. At this time, the rear group frame14(the rear group frame14on the lens barrel11A side) that holds the rear group AR is covered from the back side (rear side) by the rear group frame accommodating section42provided on the base frame12of the lens barrel11B. However, the rear group frame accommodating section42on the lens barrel11B side is not in contact with the rear group frame14on the lens barrel11A side because there is a clearance therebetween in the front-to-back direction. Accordingly, the rear group frame14of the lens barrel11A side is maintained (held) at a proper position within the rear group frame holder37on the base frame of the lens barrel11A. Similarly, the rear group frame14(the rear group frame14on the lens barrel11B side) that holds the rear group BR is covered from the back side (front side) by the rear group frame accommodating section42provided on the base frame12of the lens barrel11A. However, the rear group frame accommodating section42on the lens barrel11A side is not in contact with the rear group frame14on the lens barrel11B side because there is a clearance therebetween in the front-to-back direction. Accordingly, the rear group frame14of the lens barrel11B side is maintained (held) at a proper position within the rear group frame holder37on the base frame of the lens barrel11B. In that manner, the base frames12are stably positioned with a high degree of accuracy using the contact surfaces50and51, and thus each rear group frame14can be accommodated at a proper position of the rear group frame accommodating section42of each base frame12without any interference.

Each of the contact surface50and the contact surface51is a plane perpendicular to the optical axis X1, and has a symmetrical shape along the front-to-back direction. With such a configuration, when the lens barrel11A is brought into contact with the lens barrel11B along the optical axis X1in the front-to-back direction so as to cause the contact surface50to contact the contact surface51, no excess force is generated and a reliable and accurate positioning is made along the front-to-back direction.

The boss52having the contact surface50and the boss53having the contact surface51are both easily formed by a mold that separates in the front-to-back direction. Thus, the base frame12can be easily manufactured without an increase in cost.

When the lens barrel11A is fixed to the lens barrel11B with the contact surfaces50and51contact each other, the upper walls21, the side walls22, and the side walls23of the base frames12are combined to form the outer wall of the composite lens barrel10that continuous in the front-to-back direction. More specifically, on the upper surface of the composite lens barrel10, the edge portions of the upper walls21(top portion21a) of the lens barrel11A and the lens barrel11B are in contact with each other. On the left side surface of the composite lens barrel10, the edge portion of the side wall22of the lens barrel11A is in contact with the edge portion of the side wall23of the lens barrel11B. On the right side surface of the composite lens barrel10, the edge portion of the side wall23of the lens barrel11A is in contact with the edge portion of the side wall22of the lens barrel11B. These edge portions are opposed to each other with a slight clearance therebetween when the contact surfaces50and51contact each other, which exerts no influence on the positioning accuracy in the front-to-back direction by the contact surface50contacting the contact surface51. A light shielding structure (a light shield: a rib21d, a rib21e, a rib22a, a rib23a) that prevents undesirable external light from entering the composite lens barrel10even with a clearance therebetween is provided at each edge portion of the upper wall21, the side wall22, and the side wall23.

Specifically, as illustrated inFIGS. 16 and 17, the ribs21dand21eare disposed at the end of the top portion21a. The ribs21dand21eof the lens barrel11A and the ribs21dand21eof the lens barrel11B have relative positions to overlap with each other along the up-to-down direction when the lens barrel11A and the lens barrel11B are combined. The ribs22aand23aare disposed at the ends of the side walls22and the side walls23of the lens barrel11A and the lens barrel11B, and have relative positions to overlap with each other along right-to-left direction when the lens barrel11A and the lens barrel11B are combined. With such an overlap, external light is blocked. As illustrated inFIGS. 7, 11, and 17, a rib21fis disposed on the side portion21cand projects backward from the top portion21a. When the lens barrel11A and the lens barrel11B are combined, the rib21foverlaps with a part of the side portion21bof the corresponding lens barrel in the right-to-left direction (seeFIG. 7). With such a configuration in which the rib21foverlaps with the side portion21b, external light is blocked.

As described above, the relative positions of the lens barrel11A and the lens barrel11B in the front-to-back direction are determined by the contact surface50contacting the contact surface51. Further, a predetermined clearance is provided along the front-to-back direction between the lens barrel11A and the lens barrel11B in an area except the areas of the contact surface50and the contact surface51.

Each of the upper wall35aand the lower wall35bof the first prism holder35is formed such that the edge facing the back side has a stepwise shape formed by continuous sets of a plane perpendicular to the optical axis X1and a plane parallel to the optical axis X1. When the lens barrel11A and the lens barrel11B are combined, the stepped edge of the upper wall35aof one of the lens barrel11A and the lens barrel11B is opposed to the stepped edge of the lower wall35bof the other lens barrel11A or11B in the front-to-back direction with a slight clearance. When an excessive load (an excessive load in a direction in which the lens barrel11A and the lens barrel11B are brought together) is applied to the lens barrel11A and the lens barrel11B in the front-to-back direction, the edge of the upper wall35a(the lower wall35b) of the lens barrel11A comes into contact with the edge of the upper wall35a(the lower wall35b) of the lens barrel11B, which receives the load. That is, the opposing portions of the upper wall35aand the lower wall35bare used as an auxiliary contact surface to distribute the load between the lens barrel11A and the lens barrel11B, which strengthens the composite lens barrel10as a whole. Since the edges of the upper wall35aand the lower wall35b, i.e., the planes perpendicular to the optical axis X1are opposed to each other, unnecessary component forces are not generated when the planes are brought into contact, so that the loads are reliably received by the planes. Particularly, the position at which the first prism holder35is provided is around the intermediate position between the contact surface50and the contact surface51which are significantly separated right-to-left direction, and a position at which the first prisms AP1and BP1are held having a significant influence on the optical performance. By receiving the load with the front and back load with the first prism holders35as an auxiliary tool, the strength of the composite lens barrel10as a whole is increased and the optical performance is obtained.

As described above, when the lens barrel11A and the lens barrel11B are combined, the cylindrical portion14aof the rear group frame14fits in the space between the rear group frame holder37and the rear group frame accommodating section42, which are opposed to each other in the front-to-back direction. On the back side of the base frame12, a rear group frame opposing part56is formed in the rear group frame holder37(seeFIGS. 16 to 19). The rear group frame opposing part56is a plane perpendicular to the optical axis X1. As illustrated inFIG. 13, the rear group frame14has an opposing convex portion14fon the front side facing the rear group frame holder37of the base frame12. The opposing convex portion14fis provided at a position facing the rear group frame opposing part56of the base frame12with the rear group frame14attached to the base frame12. In view of design, the opposing convex portion14fis configured to contact the rear group frame opposing part56. If there is a tolerance error that separates the opposing convex portion14ffrom the rear group frame opposing part56, a flexible member is inserted between the base frame12and the rear group frame14to give a biasing force to the rear group frame14so as to come into contact with the rear group frame opposing part, which provides a stable contact action. Specifically, when the opposing convex portion14fof the rear group frame14is separated from the rear group frame opposing part56on the lens barrel11A side, a flexible member is disposed on the inner surface of the rear group frame accommodating section42of the base frame12on the lens barrel11B side. Accordingly, the rear group frame14on the lens barrel11A is pressed forward to make the opposing convex portion14fcontact the rear group frame opposing part56. In such a manner, the position of the rear group frame14is controlled with high accuracy in each of the lens barrels11A and11B. Note that the positioning of the rear group frame14does not hamper the positioning of the lens barrels11A and11B using the contact surfaces50and51.

A description is given of a configuration that determines the positions of the lens barrel11A and the lens barrel11B in a direction perpendicular to the optical axis X1. In this configuration, the base frame12on the lens barrel11A side is a supporting holder (which is referred to simply as a holder) as a positioning reference, and the base frame12on the lens barrel11B is a supported lens barrel to be positioned. The base frame12of each of the lens barrel11A and lens barrel11B has a first hole60and a second hole61. A first hole60is formed inside a cylindrical boss62projecting forward and backward beyond the corner wall24, and a second hole61is formed inside a cylindrical boss63projecting forward and backward beyond the corner wall25. The boss62is positioned above the boss52having the contact surface50, and the boss63is positioned above the boss53having the contact surface51. Both the first hole60and the second hole61are through-holes penetrating the base frame12in the front-to-back direction. The first hole60and the second hole61are provided at substantially symmetrical positions (substantially equidistant from the virtual plane Q1in the right-right-to-left direction) with respect to the virtual plane Q1(FIG. 5) including the optical axis X1and extending in the up-to-down direction.

The first hole60has a circular hole60aand an elongated hole60bwhich are communicable with each other in the front-to-back direction. The circular hole60ais positioned on the back surface of the base frame12, and the elongated hole60bis positioned on the front surface of the base frame12. The circular hole60ais a circular hole having a cylindrical inner peripheral surface around an axis oriented in the front-to-back direction. The elongated hole60bis an elongated hole having a long direction along the right-to-left direction (the radial direction of the circular hole60a) perpendicular to the front-to-back direction (the axial direction of the first hole60), and has a pair of parallel planes60copposed to each other up-to-down direction inside. Each plane60cis a plane parallel to the optical axes X1, X2, and X4and perpendicular to the optical axis X3. The pair of planes60care formed at positions vertically symmetrical about the axis of the circular hole60a. As illustrated inFIGS. 22A, 22B, 26A, and 26B, the vertical dimension K2(the distance between the pair of planes60c) of the elongated hole60bis smaller than the inner diameter K1of the circular hole60a. Further, the length M2of the elongated hole60bin the front-to-back direction is longer than the length M1of the circular hole60ain the front-to-back direction.

The second hole61has a circular hole61aand a small diameter hole61bwhich are communicable with each other in the front-to-back direction. The circular hole61ais positioned on the back surface of the base frame12, and the small diameter hole61bis positioned on the front surface of the base frame12. Each of the circular hole61aand the small diameter hole61bis a circular hole having a cylindrical inner peripheral surface around an axis oriented in the front-to-back direction. The circular hole61aand the small diameter hole61bhave different inner diameters. As illustrated inFIGS. 22A, 22B, 26A, and 26B, the inner diameter K4of the small diameter hole61bis smaller than the inner diameter K3of the circular hole61aThe length M3of the circular hole61ain the front-to-back direction is longer than the length M4of the elongated hole60bin the front-to-back direction.

In the first hole60and the second hole61, the inner diameter K1of the circular hole60ais substantially equal to the inner diameter K3of the circular hole61a, and the vertical width K2of the elongated hole60bis substantially equal to the inner diameter K4of the small diameter hole61b. Regarding the length in the front-to-back direction is, the length M3of the circular hole61ais longer than the length M2of the elongated hole60b. The length M2of the elongated hole60bis longer than the length M1of the circular hole60a. The length M1of the circular hole60ais longer than the length M4of the small diameter hole61b.

The entire length of the first hole60in the front-to-back direction is substantially the same as the entire length of the second hole61in the front-to-back direction. The first hole60has a tapered shape between the circular hole60aand the elongated hole60bwhose width gradually decreases in a direction from the circular hole60ato the elongated hole60b. The entire length of the first hole60includes the length of the tapered portion.

Shaft member65(a first shaft member) and the shaft member66(a second shaft member) are inserted into the first hole60and the second hole61of the base frame12, respectively in each of the lens barrels11A and11B. The shaft member65and the shaft member66are made of metal.FIGS. 22A, 22B, 26A, and 26Bare enlarged views of the shaft member65and the shaft member66, respectively.

The shaft member65has a shaft portion65a(a first insertion section) and a shaft (a second insertion section)65baligned in the front-to-back direction, and a flange65c(one restriction part) between the shaft portion65aand the shaft portion65b. The shaft portion65aand the shaft portion65bhave cylindrical outer surfaces around the same axial line oriented in the front-to-back direction, and the outer diameters of the shaft portion65aand the shaft portion65bare substantially equal. The flange65chas a larger diameter than the outer diameter of the shaft portion65aand the shaft portion65bdoes, and is an annular portion projecting from the outer surface of the shaft portion65aand the shaft portion65b.

The lengths of the shaft portion65aand the shaft portion65bin the front-to-back direction are equal to each other, and are slightly shorter than the length M1of the circular hole60a in the first hole60. The shaft portion65aand the shaft portion65bare symmetrical in the axial direction (the outer diameters and the lengths are the same) with respect to the flange65c. Accordingly, if the shaft member65is inverted back and forth so that the shaft portion65afaces the back side and the shaft portion65bfaces the front side, the same structure is obtained.

The outer diameter of the shaft portion65aand the shaft portion65bis substantially equal to the inner diameter K1of the circular hole60aand the inner diameter K3of the circular hole61a. More specifically, the outer diameter of the shaft portion65aand the shaft portion65bis slightly larger than the inner diameters K1and K3, and both the shaft portion65aand the shaft portion65bare inserted into the circular hole60aand the circular hole61awith a light press-in force.

The shaft member66includes a large diameter shaft66a(a first shaft) and a small diameter shaft66b(a second shaft) arranged in the front-to-back direction, and a flange66c(the other restricting part) between the large diameter shaft66aand the small diameter shaft66b. The large diameter shaft66aand the small diameter shaft66bhave cylindrical outer surfaces around the same axial line oriented in the front-to-back direction. The outer diameter of the large diameter shaft66ais larger than the outer diameter of the small diameter shaft66b. In addition, the length of the large diameter shaft66ain the front-to-back direction is larger than the small diameter shaft66bdoes.

The large diameter shaft66afurther includes a base end section66dclose to the flange66cand a tip section66efar from the flange66c. The base end section66dhas a larger outer diameter than the tip section66edoes. The entire length of the large diameter shaft66a(the sum of the lengths of the base end sections66dand the tip section66e) in the front-to-back direction is longer than the total length of the length M1of the circular hole60aand the length M4of the small diameter hole61b, and shorter than the total length of the length M2of the elongated hole60band the length M3of the circular hole61a. In addition, the length of the base end section66din the front-to-back direction is longer than the length of the tip section66e.

The small diameter shaft66bfurther includes a base end section66fclose to the flange66cand a tip section66gfar from the flange66c. The base end section66fhas a larger outer diameter than the tip section66gdoes. The entire length of the small diameter shaft66b(the sum of the lengths of the base end sections66fand the tip section66g) in the front-to-back direction is slightly longer than the total length of the circular hole60a, and is also slightly longer than the total length of the circular hole61a. In addition, the length of the base end section66fin the front-to-back direction is longer than the length of the tip section66g. The length of the base end sections66fis longer than each of the length M1of the circular hole60a, the length M2of the elongated hole60b, and the length M4of the small diameter hole61b. The length of the base end sections66fis slightly shorter than the length M3of the circular hole61a. The length of the tip section66gis slightly larger than the length M4of the small diameter hole61band slightly smaller than the length M1of the circular hole60a.

The outer diameter of the large diameter shaft66ais substantially equal to the inner diameter K1of the circular hole60aand the inner diameter K3of the circular hole61a. More specifically, the outer diameter of the base end section66dof the large diameter shaft66ais slightly larger than the inner diameters K1and K3, and the outer diameter of the tip section66eis slightly smaller than the inner diameters K1and K3. Accordingly, the large diameter shaft66ais inserted into the circular hole60aor the circular hole61awith the base end section66dlightly press-fit.

The outer diameter of the small diameter shaft66bis substantially equal to the vertical width K2of the elongated hole60band the inner diameter K4of the small diameter hole61b. More specifically, the outer diameter of the base end section66fof the small diameter shaft66bis slightly larger than the vertical width K2and the inner diameter K4, and the outer diameter of the tip section66gis slightly smaller than the vertical width K2and the inner diameter K4. Accordingly, the small diameter shaft66bis inserted into the elongated hole60bor the small diameter hole61bwith the base end section66flightly press-fit. However, actually, the insertion of the base end section66finto the small diameter hole61bis restricted by the flange66c(seeFIG. 28).

In the drawings of the present embodiments, cases in which the position of the lens barrel11B is adjusted with reference to the lens barrel11A are illustrated. That is, cases in which the lens barrel11A is a reference supporting lens barrel and the lens barrel11B is a supported lens barrel to be positioned are described.

First, as illustrated inFIGS. 20A and 20B, the shaft portion65aof the shaft member65is inserted into the first hole60on the lens barrel11A side from the back side. The insertion of the shaft member65is restricted at a position at which the flange65ccontact the end face on the back side of the boss62. Since the length of the shaft portion65ais smaller than the length M1of the circular hole60a, the shaft portion65ais inserted to the circular hole60awithout reaching the position of the elongated hole60b(seeFIGS. 22A and 22B). Since the outer diameter of the shaft portion65ais slightly larger than the inner diameter K1of the circular hole60a, the shaft portion65ais lightly press-fit by the circular hole60a, and the shaft member65is stably mounted onto the base frame12on the lens barrel11A side without rattling.

Further, as illustrated inFIGS. 24A and 24B, the large diameter shaft66aof the shaft member66is inserted into the second hole61on the lens barrel11A side from the back side. The insertion of the shaft member66is restricted at a position where the flange66ccomes into contact with the end face on the back side of the boss63. Since the length of the large diameter shaft66ais smaller than the length M3of the circular hole61a, the large diameter shaft66ais inserted to the circular hole61awithout reaching the position of the small diameter hole61b(seeFIGS. 26A and 26B). Since the outer diameter of the base end section66dis slightly larger than the inner diameter K3of the circular hole61a, the large diameter shaft66ais lightly press-fit by the circular hole61a, and the shaft member66is stably mounted onto the base frame12on the lens barrel11A side without rattling.

Since the outer diameter of the tip section66eof the large diameter shaft66ais slightly smaller than the inner diameter K3of the circular hole61a, the large diameter shaft66ais smoothly inserted into the circular hole61awithout being press-fit at the initial stage of insertion. In other words, the large diameter shaft66ais configured to be press-fit at the final stage of insertion at which a stable support is needed, which facilitates improves insertion.

FIG. 19is an illustration of the shaft member65and the shaft member66attached to the base frame12on the lens barrel11A side. As can be seen fromFIG. 19, the shaft portion65bof the shaft member65and the small diameter shaft66bof the shaft member66project backward (to the back side of the lens barrel11A).

The shaft member65and the shaft member66are attached to the lens barrel11A at any desired timing. For example, as illustrated inFIG. 19, the shaft member65and the shaft member66are attached to a simplex base frame12in advance, and subsequently other components (for example, the rear group frame14, the third prism frame15, and the image sensor unit16) are attached to the base frame12. Alternatively, the components other than the shaft member65and the shaft member66are first attached to the base frame12, and then the shaft member65and the shaft member66are attached to the base frame12. In either case, since the shaft member65and the shaft member66are press-fit by the base frame12, there is no possibility that the shaft member65and the shaft member66might fall accidentally after assembling. The first hole60and the second hole61, into which the shaft member65and the shaft member66are inserted, are positioned on an upper end of the base frame12, the upper end being away from the first prism holder35, the second prism holder36, the rear group frame holder37, and the rear group frame accommodating section42. With such an arrangement, after assembling the components other than the shaft members65and66to the base frame12, it is still easy to access the first hole60and the second hole61to assemble the shaft members65and66.

Subsequently, the lens barrel11B is attached to the lens barrel11A in which the shaft member65and the shaft member66are assembled. The second hole61(circular hole61a) on the lens barrel11B side is opposed to the shaft portion65bof the shaft member65, and the first hole60(circular hole60a) on the lens barrel11B side is opposed to the small diameter shaft66bof the shaft member66. That is, the circular hole60aon the lens barrel11A side and the circular hole61aon the lens barrel11B side are a pair of holes opposed to each other in the front-to-back direction, and the circular hole61aon the lens barrel11A side and the circular hole60aon the lens barrel11B is a pair of holes opposed to each other in the front-to-back direction. When the lens barrel11A and the lens barrel11B are brought together in the front-to-back direction, the shaft portion65bis inserted into the second hole61of the lens barrel11B (FIG. 21), and the small diameter shaft66bis inserted into the first hole60of the lens barrel11B (FIG. 25).

As described above, the contact surfaces50and51of the lens barrels11A and11B contact each other, which restricts further approach (the positions of the lens barrel11A and the lens barrel11B in the front-to-back direction is determined). As illustrated inFIGS. 22A, 22B, 26A, and 26B, when the contact surface50contacts the contact surface51, there is a gap N in the front-to-back direction between the opposing end faces of the boss62and63on the base frames12of the lens barrels11A and11B. The thickness of each of the flange65cof the shaft member65and the flange66cof the shaft member66is slightly smaller than the gap N. Accordingly, the shaft member65and the shaft member66do not hamper positioning of the lens barrels11A and11B in the front-to-back direction using the contact surfaces50and51.

As illustrated inFIGS. 22A and 22B, since the length of the shaft portion65bis shorter than the length M3of the circular hole61a, the shaft portion65bis inserted to the circular hole61awithout reaching the position of the small diameter hole61bin the second hole61on the lens barrel11B side. Since the circular hole61aof the cylindrical inner surface fits to the shaft portion65bof the cylindrical outer surface, the movement of the base frame12on the lens barrel11B side in the radial direction of the shaft portion65b(all the direction perpendicular to the direction in which the first hole60and the second hole61are opposed to each other (the optical axis X1)) is restricted. With such a configuration, the relative positions of the lens barrel11A and the lens barrel11B are determined within a plane perpendicular to the optical axis X1.

Since the outer diameter of the shaft portion65bis slightly larger than the inner diameter K3of the circular hole61a, the shaft portion65bis lightly press-fit by the circular hole61a. Accordingly, with the lens barrel11A and the lens barrel11B combined, the shaft member65might not rattle and generate abnormal noise.

As illustrated inFIGS. 26A and 26B, the small diameter shaft66bis inserted from the circular hole60aside to the elongated hole60bso as to be inserted into the first hole60on the lens barrel11B side. Since the outer diameters of the base end section66fand the tip section66gare both smaller than the inner diameter K1of the circular hole60a, the small diameter shaft66bdoes not contact the inner surface of the first hole60in the initial stage of insertion.

When the small diameter shaft66bmoves deeper inside of the first hole60, the tip section66gof the small diameter shaft66benters the elongated hole60b. Since the outer diameter of the tip section66gis smaller than the vertical width K2of the elongated hole60b, no load is generated between the shaft member66and the first hole60at this stage. When the small diameter shaft66bmoves still further inside of the first hole60, the base end section66fof the small diameter shaft66benters the elongated hole60b. Then, the base end section66fis sandwiched between a pair of up and down planes60cin the elongated hole60b, and accordingly a vertical movement of the base frame12on the lens barrel11B side is restricted with respect to the small diameter shaft66b. As a result, the rotation of the lens barrel11A relative to the lens barrel11B around the shaft member65is restricted.

Further, since the length of the elongated hole60bin the right-to-left direction is larger than the outer diameter of the base end section66f, the small diameter shaft66bdoes not restrict the position of the lens barrel11B in the right-to-left direction. That is, the elongated hole60bof the lens barrel11B is movable relative to the small diameter shaft66bonly in a certain direction (the right-to-left direction) within a plane perpendicular to the direction in which the first hole60and the second hole61are opposed to each other (the direction along the optical axis X1). With such a configuration, the small diameter shaft66band the first hole60work to cancel out the assembly tolerances between the lens barrel11A and the lens barrel11B.

Note that since the outer diameter of the base end section66fis slightly larger than the vertical width K 2 of the elongated hole60b, the small diameter shaft66bis lightly press-fitted into the elongated hole60b. Accordingly, with the lens barrel11A and the lens barrel11B combined, the shaft member66might not rattle and generate abnormal noise. As described above, since the tip section66gis provided at the tip end of the small diameter shaft66b, no press-fitting occurs until the small diameter shaft66bis advanced to some extent inside the elongated hole60b. With this configuration, the timing at which the small diameter shaft66b(base end section66f) of the shaft member66is press-fitted into the elongated hole60bof the first hole60becomes substantially the same as the timing at which the shaft portion65bof the shaft member65is press-fitted into the circular hole61aof the second hole61. Accordingly, the lens barrel11B is combined with the lens barrel11A without being tilted. Unlike the present embodiment, if the tip section66gis not provided in the small diameter shaft66band the small diameter shaft66bas a whole has the same diameter as that of the base end section66f, the timing at which the small diameter shaft66bis press-fit into the elongated hole60bof the first hole become significantly earlier than the timing at which the shaft portion65bis press-fit into the circular hole61aof the second hole61. Accordingly, the lens barrel11B is likely to be tilted relative to the lens barrel11A with the location of the shaft member66and the first hole60as a fulcrum.

As illustrated inFIGS. 26A and 26B, since the length of the small diameter shaft66bis slightly longer than the entire length of the first hole60, the small diameter shaft66bpasses through the first hole60on the lens barrel11B side so that the tip section66gprojects to the back side of the lens barrel11A beyond the boss63. With such a configuration, although the lens barrel11A and the lens barrel11B have the same symmetrical shape along the front-to-back direction, it is easier to identify the front side of the lens barrel11B at which the shaft member66projects beyond the boss63, which improves the workability.

As described above, the shaft member65and the shaft member66are press-fit into the first hole60and the second hole61, respectively. However, if the load of press-fitting is too large, workability deteriorates or distortion occurs on the base frame12side, which might affect positioning accuracy. In order to avoid such a situation, the relative diameters of the first hole60, the second hole61, and the shaft members65and66are set so as to be slightly press fit without impairing the positioning accuracy.

The positions at which the shaft member65and the shaft member66are positioned are close to the positions at which positioning is made by the contact surface50and the contact surface51along the front-to-back direction. The shaft member65and the shaft member66are disposed substantially symmetrically with respect to the virtual plane Q1(FIG. 5) that includes the optical axis X1and extends along the up-to-down direction. With such a configuration in which the distance between the shaft member65and the shaft member66along the right-to-left direction is increased, and in which the shaft member65and the shaft member66are disposed symmetrically in positions relative to the front group AF and BF and the first prisms AP1and BP1, the accuracy of positioning is increased.

The first hole60and the second hole61into which the shaft member65and the shaft member66are inserted are arranged in the corner wall24and the corner wall25, respectively of the base frame12, which enables space to be efficiently utilized without interfering with the other components constituting the lens barrel11A and lens barrel11B. In addition to the rigidity of the corner walls24and25, the thickness of the boss62having the first hole60and the boss63having the second hole61also provide reinforcement. Accordingly, the first hole60and the second hole61are not likely to be displaced by using the shaft member65and the shaft member66.

The first hole60and the second hole61are also used to attach an exterior member attaching an exterior member constituting the outer surface of the imaging apparatus80thereto. The front cover70inFIGS. 23 and 27is an exterior member that covers the front side of the imaging apparatus80. The front cover70has a support protrusion71(FIG. 23) projecting backward and a support protrusion72(FIG. 27) on the inner surface side. The support protrusion71and the support protrusion72are provided to correspond to the first hole60and the second hole61in the base frame12, respectively. The support protrusion71has a cylindrical outer surface portion having a constant outer diameter around the tip of the support protrusion71. The outer diameter of the cylindrical outer surface is substantially the same as the vertical width K2of the elongated hole60bin the first hole60. The support protrusion72has a cylindrical outer surface portion having a constant outer diameter around the tip portion of the support protrusion72. The outer diameter of the cylindrical outer surface portion is substantially the same as the vertical width K4of the small diameter hole61bin the second hole61.

In attaching the front cover70to the composite lens barrel10, the tip portion (cylindrical outer surface portion) of the support protrusion71is inserted from the front side into the elongated hole60bof the first hole60on the lens barrel11A side. Further, the tip portion (cylindrical outer surface portion) of the support protrusion72is inserted from the front side into the small diameter hole61bof the second hole61on the lens barrel11A side. On the lens barrel11A, the shaft portion65aof the shaft member65has not entered the elongated hole60byet, and the large diameter shaft66aof the shaft member66has not entered the small diameter hole61byet either. Accordingly, the support protrusion71and the support protrusion72are successfully inserted into the first hole60and the second hole61, respectively without interfering with the shaft member65and the shaft member66.

The support protrusion72of the cylindrical outer surface fits the small diameter hole61bof the cylindrical inner surface, so that the front cover70is positioned within a plane perpendicular to the optical axis X1. Further, the support protrusion71is sandwiched between the pair of planes60cof the elongated hole60b, which restrict the rotation of the front cover70around the support protrusion72. The length of the elongated hole60bin the right-to-left direction is longer than the outer diameter of the support protrusion71, and the position of the support protrusion71in the right-to-left direction is not restricted by the elongated hole60b. With such a configuration, the support protrusion71and the first hole60work to cancel out assembly tolerances of assemble of the front cover70and the composite lens barrel10. In that manner, the first hole60and the second hole61are used to position the shaft member65and the shaft member66and also used to assemble and position the front cover70.

In the lens barrel11B side, the small diameter shaft66bof the shaft member66passes through the first hole60as a whole (seeFIGS. 26A and 26B), whereas the shaft member65has not entered the small diameter hole61bof the second hole61yet (FIGS. 22A and 22B). Accordingly, a protrusion of another member (for example, a back cover constituting an exterior component of the imaging apparatus80together with the front cover70) is inserted from the back side into the small diameter hole61bof the lens barrel11B so as to position the another member.

As the shaft member65has a symmetrical shape in the axial direction, the orientations of the shaft portion65aand the shaft portion65bmay be reversed. However, as the shaft member66has an asymmetrical shape along the axial direction, the large diameter shaft66aand the small diameter shaft66b, whose orientations are reversed, fail in assembly and malfunction. The imaging apparatus80according to the present embodiment has a structure that prevents the shaft member66from being assembled in an opposite direction.

FIG. 28is an illustration of a case in which the shaft member66is assembled in the opposite direction. The small diameter shaft66bis inserted into the second hole61on the lens barrel11A. The outer diameter of the base end section66fof the small diameter shaft66bis shorter than the inner diameter K3of the circular hole61a, and the outer diameter of the tip section66gis shorter than the inner diameter K4of the small diameter hole61b. With such a configuration, the small diameter shaft66bcan be advanced inside the second hole61to reach the position at which the flange66ccontacts the back-side end face of the boss63.

The length of the large diameter shaft66ais longer than the length M1of the circular hole60aof the first hole60. Accordingly, when the large diameter shaft66ais inserted into the first hole60of the lens barrel11B side, the tip of the large diameter shaft66aabuts against the step in the boundary between the circular hole60aand the elongated hole60bearlier than the contact surfaces50and51contact each other. Thus, further insertion is restricted. In this state, there is a large gap in the front-to-back direction between the flange66cand the boss63, which allows for recognition that the lens barrel11A and the lens barrel11B are prevented from being close to each other due to the assembly failure of the shaft member66.

In assembling the front cover70(FIG. 23andFIG. 27) to the composite lens barrel in the state ofFIG. 28, the support protrusion72abuts against the small diameter shaft66b, so that the support protrusion72fails to be inserted into the second hole61(the small diameter hole61b). Accordingly, the front cover70is not fit into the front-side composite lens barrel10, which also allows for recognition that the shaft member66fails in assembly.

In the present embodiment, the case in which the lens barrel11B is positioned with reference to the lens barrel11A side is described. However, in some embodiments, the lens barrel11A may be positioned with reference to the lens barrel11B because the lens barrel11A and the lens barrel11B have the same shape. In other words, it is also possible to reverse the supporting lens barrel as the reference for positioning (the base frame12as the supporting holder (a holder)) and the supported lens barrel (the base frame12as the supported holder (another holder)) to be positioned by the support barrel. Specifically, the shaft member65(which may be either of the shaft portion65aand the shaft portion65b) is inserted into the first hole60(the circular hole60a) on the lens barrel11B, and the large diameter shaft66aof the shaft member66is inserted into the second hole61(the circular hole61a) on the lens barrel11B side. Subsequently, the shaft member65(one of the shaft portion65aand the shaft portion65bthat is not inserted into the first hole60of the lens barrel11B) is inserted into the second hole61(the circular hole61a) on the lens barrel11A side, and the small diameter shaft66bof the shaft member66is inserted into the first hole60(the elongated hole60b) on the lens barrel11A side.

In the present embodiment as described above, the lens barrel11A including the wide-angle lens system A and the image sensor AI is combined with the lens barrel11B including the wide-angle lens system B and the image sensor BI to constitute the composite lens barrel10. Each imaging system is housed in a corresponding lens barrel11A/11B, which facilitates assembling the optical components in each of the lens barrels11A and11B, and thus increases the productivity. Further, two lens barrels whose imaging performances are similar are selected as the lens barrel11A and the lens barrel11B to be combined. Accordingly, it is easy to control the performance of the imaging system1as a whole. In a mode that assembles a plurality of optical systems in one lens barrel, when any failure is found in one optical system after the assembly of the lens barrel is completed (in particular, after the parts are fixed by, for example, adhesion), the entire system including the other optical systems with no failure has to be discarded, resulting in waste. However, the configuration according to the embodiments of the present disclosure that combines the lens barrel11A and the lens barrel11B is advantageous to an increase in productivity and a reduction in cost without any waste.

In such a configuration according to the embodiments of the present disclosure, the two lens barrels11A and11B are positioned in the direction perpendicular to the optical axis X1using the shaft member65and the shaft member66such that the lens barrel11A and the lens barrel11B are opposed to each other. The shaft member65serves as a main-reference positioning mechanism that restricts the movement of the first hole60and the second hole61of each of the lens barrels11A and11B along the all the direction perpendicular to the optical axis X1. The shaft member66serves as a sub-reference positioning mechanism that allows the first hole60to move along a certain direction perpendicular to the optical axis X1and restricts movement in the other directions. With this configuration, an error between the lens barrels11A and11B is cancelled out and a high accuracy of positioning is achieved while the lens barrel members constituting the lens barrel11A and the lens barrel11B (in particular, the base frame12to be positioned) have the same shape.

Each of the first hole60and the second hole61has a simple shape in which the opening area inside consists of two phases, and is easily manufactured when the base frame12is formed. The first hole60and the second hole61in the lens barrel11A and the second hole61and the first hole60in the lens barrel11B are opposed to each other, respectively. The shaft members65and66are inserted into these holes so that the lens barrel11A and the lens barrel11B are positioned. That is, the lens barrel11A and the lens barrel11B are easily assembled without complicated work.

As described above, either one of the lens barrel11A and the lens barrel11B may be selected as the reference supporting lens barrel. Further, the imaging apparatus81has the structure that allows the worker to easily recognize a proper manner to assemble the shaft member66having an asymmetrical shape along the axial direction in the lens barrels11A and11B (seeFIG. 28). Accordingly, wrong installation of the components in combining the lens barrels11A and11B can be avoided.

As the lens barrel11A and the lens barrel11B have the same shape as a whole including the first hole60and the second hole61, it is possible to reduce the number of parts, manufacturing cost, and time as compared with a configuration in which a plurality of lens barrels having different structures are combined. Further, in this configuration, the shaft members65and66are directly inserted into the first holes60and the second holes61of the base frames12constituting the lens barrel11A and the lens barrel11B so as to position the lens barrel11A and lens barrel11B. This configuration provides a low-cost and simple structure of the lens barrel and facilitates accuracy control between the lens barrels, as compared to a configuration that includes another large member on which two lens barrels are mounted.

With reference toFIGS. 35 and 36, a description is given of the overall configuration of a full-view spherical imaging apparatus to which the imaging system1and the composite lens barrel10according to an embodiment of the present disclosure are applied.FIGS. 35and36are illustrations of a typical configuration of a spherical imaging system although the wide-angle lens systems A and B and the image sensors AI and BI are differently arranged from the above-described composite lens barrel10. The characteristic configurations of the imaging optical system (the optical system), the imaging system, and the imaging apparatus are as described above (FIGS. 1 to 34).

As illustrated inFIG. 35, the imaging apparatus80includes an imaging body81, a casing82that holds components such as the imaging body81, a controller, and a battery inside, and a shutter button83provided on the outer surface of the casing82. The casing82includes an exterior component that corresponds the front cover70according to the above-described embodiment. InFIG. 35, although only the image-forming optical systems84A and84B and the solid-state image sensors85A and85B are illustrated within the casing82of the imaging apparatus80, the structure that corresponds to the composite lens barrel10according to the above-described embodiments (FIGS. 1 to 34) is actually mounted within the casing82.

The imaging body81inFIG. 35corresponds to the imaging system1of the composite lens barrel10. The imaging body81includes two image-forming optical systems84A and84B and two solid-state image sensors85A and85B. Examples of the two solid-state image sensors85A and85B include charge-coupled devices (CCDs) and complementary metal oxide semiconductors (CMOSs). A combination of one image-forming optical system84A/84B and one solid-state image sensor85A/85B constitutes the imaging system. Each of the image-forming optical systems84A and84B is configured as a fish-eye lens consisting of, for example, seven lenses in six groups. In the embodiment illustrated inFIG. 35, the fish-eye lens has an wide angle of view of 180 (360/n, n is 2) degrees or more, preferably 185 degrees or more, and more preferably 190 degrees or more.

The positions of the optical elements (the lens, the prism, the filter, and the aperture stop) of the two image-forming optical systems84A and84B are defined relative to the solid-state image sensor85A and85B. Such positions are defined such that the optical axes of the optical elements of the image-forming optical systems84A and84B are orthogonal to the central portion of the light-receiving areas of the corresponding solid-state image sensors85A and85B, and such that each light-receiving area serves as an image-forming plane of the corresponding fish-eye lens. Each of the solid-state image sensors85A and85B is a two-dimensional solid-state image sensor defines a light-receiving area. The solid-state image sensors85A and85B convert light focused by the image-forming optical systems84A and84B into electrical signals, respectively.

In the imaging apparatus80illustrated inFIG. 35, the image-forming optical systems84A and84B have the same specification, and are combined to face in opposite directions from each other with the optical axes matching with each other. Each of the solid-state image sensors85A and85B converts a received light distribution into an image signal and outputs the signal to an image processing unit on the controller. The image processing unit joins partial-view images transmitted from the solid-state image sensors85A and85B to obtain an image with a solid angle of 4π steradian (referred to as “spherical image” below). The omnidirectional image is an image of all the directions that can be seen from an image capturing point. In the embodiment illustrated inFIG. 35, the imaging optical system generates a spherical image. However, in some other embodiments, the imaging optical system may generate a panoramic image by capturing 360 degrees in a horizontal plane.

In the imaging optical system, the scan direction of the solid-state image sensor85A is identical with the scan direction of the solid-state image sensor85B, which enables images captured by the solid-state image sensors85A and85B to be joined easier. That is, the scan directions and scan sequences of the solid-state image sensors85A and85B are identical with each other at portions to be joined together. This configuration is advantageous to joining images of an object, particularly a moving object on the boundary between two capturing ranges of the camera. For example, when an upper-left portion of the image captured by the solid-state image sensor85A matches a lower-left portion of the image captured by the solid-state image sensor85B to join the images, the solid-state image sensor85A scans the image from right to left while scanning from top to bottom of the solid-state image sensor85A. The solid-state image sensor85B scans from bottom to top while scanning from the right to the left of the solid-state image sensor85B. That is, the scan directions of the respective solid-state image sensors85A and85B are caused to match each other based on the portions of the images to be joined, which facilitates the joining of the images.

As described above, since the fish-eye lens has a full angle of view exceeding 180 degrees, the images captured by the respective imaging optical systems A and B partly overlap with each other. Accordingly, the captured images are joined with each other based on the overlapping portions of the images as reference data representing the identical image, so as to generate a full-view spherical image. The generated spherical image is transmitted to a display device provided on or connected to the imaging body81, a printing device, and an external memory such as an SD (registered trademark) card and a compact flash (registered trademark).

FIG. 10is a block diagram of an example of a hardware configuration of the imaging apparatus80. The imaging apparatus80includes a digital still camera processor (hereinafter, simply referred to as a processor)500, a barrel unit502, and various components connected to the processor500. The barrel unit502includes the two image-forming optical systems84A and84B and the solid-state image sensors85A and85B. The solid-state image sensors85A and85B are controlled by commands from the CPU530in the processor500, which will be described later.

The processor500includes image signal processors (ISPs)508A and508B, a direct memory access controller (DMAC)510, an arbiter (ARBMEMC)512for arbitrating memory access, a memory controller (MEMC)514for controlling memory access, and a distortion correction/image composite block518. The ISPs508A and508B apply white balance correction and gamma correction to the image signals processed by the solid-state image sensors85A and85B. The MEMC514is coupled to a synchronous dynamic random access memory (SDRAM)516. The SDRAM516temporarily stores data when the ISPs508A and508B and the distortion correction/image composite block518perform processing. The distortion correction/image composite block518applies distortion correction and top-bottom correction to the partial images captured by the imaging optical systems, using data from a triaxial accelerometer520, so as to composite the images.

The processor500further includes a DMAC522, an image processing block524, the CPU530, an image data transferring unit526, a synchronous dynamic random access memory (SDRAM)528, a memory card controlling block540, a universal serial bus (USB) block546, a peripheral block550, a sound unit552, a serial block558, a liquid crystal display (LCD) driver562, and a bridge568.

The CPU530controls operations of respective elements in the imaging apparatus80. The image processing block524performs various types of image processes on image data using a resize block532, a joint photographic experts group (JPEG) block534, and H. 264 block536. The resize block532enlarges or reduces the size of the image data by interpolation processing. The JPEG block534is a codec block that performs JPEG compression and decompression. The H.264 block536is a codec block that compresses and decompresses a moving image such as H.264. The image data transferring unit526transfers the image on which the image processing has been performed by the image processing block524. The SDRAMC528controls an SDRAM538coupled to the processor500, and the SDRAM538temporarily stores image data when various processing is performed on the image data in the processor500.

The memory card controlling block540controls reading and writing from/to a memory card and a flash read only memory (ROM)544inserted into the memory card slot542. The memory card slot542is a slot to detachably attach a memory card to the imaging apparatus80. The USB block546controls USB communication to an external device such as a personal computer coupled via the USB connector548. The peripheral block550is coupled to a power switch566. The sound unit552is coupled to a microphone556that receives an audio signal from a user and a speaker554that outputs the recorded audio signal and controls sound input and output. The serial block558controls serial communication with an external device such as a personal computer and is coupled to a wireless Network Interface Card (NIC)560. The Liquid Crystal Display (LCD) driver562is a driver circuit that drives an LCD monitor564and performs conversion to a signal used to display various states on the LCD monitor564.

The flash ROM544stores a control program written in a code that can be decoded by the CPU530and various parameters. When the power is turned on by the operation of a power switch566, the control program mentioned above is loaded into the main memory. The CPU530controls operation of each part in the imaging system1according to the program loaded into the main memory, while temporarily saving data necessary for control on the SDRAM538and a local static random access memory (SRAM).

In the above-described embodiment, the circular holes (the circular holes60aand61a) and the shafts (the shafts65aand65b) having the circular cross-sectional area constitute the main-reference positioning mechanism positioning mechanism. Unlike this configuration, other types of holes and shafts having other cross-sectional shape other than the circle may constitute the main-reference positioning mechanism.FIGS. 37 to 44are illustrations of variations in which the internal shapes of the hole are different. In each of the following variations, the same elements as those of the above-described embodiments are indicated with the same reference numerals, and description thereof is omitted. The shaft member65and the shaft member66are the same as those of the above embodiments.

FIGS. 37 and 38are illustrations of a positioning mechanism according to a first variation of an embodiment of the present disclosure. In the first variation, a first hole160has an opposing hole portion90as a substitute for the circular hole60aof the above-described embodiment, and a second hole161has an opposing hole portion91as a substitute for the circular hole61aof the above-described embodiment.

The opposing hole portion90of the first hole160includes a cylindrical portion90ahaving a cylindrical inner surface and four protrusions90bprojecting inward from the inner surface of the cylindrical portion90a. Each protrusion90bhas a curved surface that is convex toward the inner diameter direction, and this curved surface has a uniform cross-sectional shape continuing in the axial direction (the front-to-back direction) of the first hole160. The four protrusions90bare disposed at substantially equal angular intervals (90° intervals) in the circumferential direction around the axis of the first hole160, and the respective protrusion amounts are equal. Two of the protrusions90bare spaced apart and opposed to each other in a long direction (the right-to-left direction) of the elongated hole60b. The remaining two protrusions90bare spaced apart and opposed to each other in the width direction (the up-to-down direction) of the elongated hole60b. The width between the opposed protrusions90bin the up-to-down direction and the width between the opposed protrusions90bin the right-to-left direction (the distance between peaks of the convex surfaces of the opposed protrusions90b). The distance between the two protrusions90bopposed to each other in the width direction (the up-to-down direction) of the elongated hole60bis longer than the distance between the pair of planes60cin the elongated hole60b.

On the lens barrel11A side, the shaft portion65aof the shaft member65is inserted into the opposing hole portion90of the first hole160. The virtual circle indicated by a two-dot chain inFIG. 37is an incircle that internally contacts the four protrusions90bof the opposing hole portion90. That is, the shaft portion65aof the shaft member65has a diameter of the circle. In this contact state, the shaft portion65ais lightly press-fitted into the opposing hole portion90. That is, the distance between the opposed protrusions90bis slightly smaller than the diameter of the shaft portion65aat the initial state. The shaft portion65acontacts each of the protrusions90bin a linear region along the axial direction of the first hole160. The shaft portion65adoes not contact each of the cylindrical portion90a. Accordingly, the contact area between the shaft portion65aand the opposing hole portion90is reduced, and thus a load imposed by insertion of the shaft portion65ais reduced as compared to the configuration in which substantially the entire outer surface of the shaft portion65acontacts the inner surface of the hole. Further, such a configuration according to the present embodiment reduces or prevents tilting of the shaft portion65a, and also advantageously advances the shaft portion65ainside the first hole160in the axial direction.

On the lens barrel11B side, the small diameter shaft66bof the shaft member66is inserted into the first hole160. In the opposing hole portion90, each of the distance between the two protrusions90bopposed to each other right-to-left direction and the distance between the two protrusions90bopposed to each other in the up-to-down direction is shorter than the diameter of the small diameter shaft66b(the base end section66fand the tip section66g). Accordingly, each protrusion90bdoes not hamper the insertion of the small diameter shaft66binto the first hole160.

Similarly to the opposing hole portion90of the first hole160, the opposing hole portion91of the second hole161has a cylindrical portion91ahaving a cylindrical inner surface and four protrusions91bprojecting inward from the inner surface of the cylindrical portion90a. The shape (inner diameter) of the cylindrical portion91aand the arrangement and shape of each protrusion91bare the same as those of the cylindrical portion90aand each protrusion90bof the opposing hole portion90. The four protrusions91bare disposed at substantially equal angular intervals (90° intervals) in the circumferential direction around the axis of the second hole161. Two of the protrusions91bare spaced apart and opposed to each other up-to-down direction, and the remaining two protrusions91bare spaced apart and opposed to each other along the right-to-left direction. Each distance between the two opposed protrusions91bis greater than the diameter of the small diameter hole61bof the second hole161.

On the lens barrel11A side, the large diameter shaft66aof the shaft member66is inserted into the opposing hole portion91of the second hole161. On the lens barrel11B side, the shaft portion65bof the shaft member65is inserted into the opposing hole portion91of the second hole161. The virtual circle indicated by a two-dot chain inFIG. 37is an incircle that internally contacts the four protrusions90bof the opposing hole portion90. That is, each of the shaft portion65band the large diameter shaft66a(the base end section66d) of the shaft member65has a diameter of the circle. In this contact state, each of the shaft portion65band the large diameter shaft66a(the base end section66d) is lightly press-fitted into the opposing hole portion90. In other words, the distance between the opposed protrusions91bis slightly smaller than the diameter of each of the shaft portion65band the base end section66dat the first stage of insertion. The shaft portion65band the large diameter shaft66a(the base end section66d) contact each of the protrusions90bin a linear region along the axial direction of the second hole161. Neither the shaft portion65bnor the large diameter shaft66acontacts the cylindrical portion91a. Accordingly, the contact area of the opposing hole portion91contacting the shaft portion65band the large diameter shaft66a(the base end section66d) is reduced, and thus a load imposed by insertion of the shaft portion65band the large diameter shaft66a(the base end section66d) is reduced. Further, such a configuration that includes the plurality of protrusions91breduces or prevents tilting of the shaft portion65a, and also advantageously advances the shaft portion65band the large diameter shaft66ainside the first hole160in the axial direction.

With the reduction in the contact area between the opposing hole portions90and91and the shaft members65and66, the assembly tolerances at the insertion location are more easily handled. In a configuration that provides a surface contact between the shaft members65,66and the entire cylindrical inner surface of the circular holes60aand61a, the resistance generated by press fitting of the shaft members65and66tends to change significantly due to a variation in the tolerances between the shaft members65and66and the holes60aand61a. By contrast, in the configuration according to the first variation of an embodiment of the present disclosure in which the shaft members65and66contact a part of the inner surface of the hole, the change in the resistance of the shaft members65and66to the hole is reduced even with the variation in the same degree of tolerances between the hole and the shaft members65and66. The same advantageous effects are obtained from the following configurations according to a second variation to a fourth variation.

FIGS. 39 and 40are illustrations of a positioning mechanism according to the second variation of an embodiment of the present disclosure. In the second variation of the embodiment, the first hole260has an opposing hole portion92as a substitute for the circular hole60aaccording to the above-described embodiment, and the second hole261has an opposing hole portion93as a substitute for the circular hole61aaccording to the above-described embodiment.

The opposing hole portion92of the first hole260includes a cylindrical portion92ahaving a cylindrical inner surface, and four planes92beach of which partially short-circuits the inner surface of the cylindrical portion92a. Each plane92bhas a planar shape that extends along the axial direction of the first hole260. The four planes92bare disposed at substantially equal angular intervals (90° intervals) in the circumferential direction around the axis of the first hole260. Two of the planes92bare spaced apart and opposed to each other in the long direction (the right-to-left direction) of the elongated hole60b. The remaining two planes92bare spaced apart and opposed to each other in the width direction (the up-to-down direction) of the elongated hole60b, being substantially parallel to the plane60cof the elongated hole60b. The width between the opposed planes92bin the up-to-down direction is equal to the width between the opposed protrusions90bin the right-to-left direction. The distance between the two planes92bopposed to each other in the width direction (the up-to-down direction) of the elongated hole60bis longer than the distance between the pair of planes60cin the elongated hole60b.

On the lens barrel11A side, the shaft portion65aof the shaft member65is inserted into the opposing hole portion92of the first hole260. The virtual circle indicated by a two-dot chain inFIG. 39is an incircle that internally contacts the four projections92bof the opposing hole portion92. That is, the shaft portion65aof the shaft member65has a diameter of the circle. In this contact state, the shaft portion65ais lightly press-fitted into the opposing hole portion92. That is, the distance between the opposed planes92bis slightly smaller than the diameter of the shaft portion65aat the initial state. The shaft portion65acontacts each of the planes92bin a linear region along the axial direction of the first hole260. The shaft portion65adoes not contact each of the cylindrical portion92a. Accordingly, the contact area between the shaft portion65aand the opposing hole portion92is reduced, and thus a load imposed by insertion of the shaft portion65ais reduced as compared to the configuration in which substantially the entire outer surface of the shaft portion65acontacts the inner surface of the hole. Further, such a configuration that includes the plurality of planes92breduces or prevents tilting of the shaft portion65a, and also advantageously advances the shaft portion65ainside the first hole260in the axial direction.

On the lens barrel11B side, the small diameter shaft66bof the shaft member66is inserted into the first hole260. In the opposing hole portion92, each of the distance between the two planes92bopposed to each other in the right-to-left direction and the distance between the two planes92bopposed to each other in the up-to-down direction is shorter than the diameter of the small diameter shaft66b(the base end section66fand the tip section66g). Accordingly, each plane92bdoes not hamper the insertion of the small diameter shaft66binto the first hole260.

Same as the opposing hole portion92of the first hole260, the opposing hole portion93of the second hole261includes a cylindrical portion93ahaving a cylindrical inner surface, and four planes92beach of which partially short-circuits the inner surface of the cylindrical portion92a. The shape (inner diameter) of the cylindrical portion93aand the arrangement and shape of each plane93bare the same as those of the cylindrical portion92aand each plane92bof the opposing hole portion92. The four planes93bare disposed at substantially equal angular intervals (90° intervals) in the circumferential direction around the axis of the second hole261. Two of the planes93bare spaced apart and opposed to each other up-to-down direction, and the remaining two planes93bare spaced apart and opposed to each other along the right-to-left direction. Each distance between the two opposed planes93bis greater than the diameter of the small diameter hole61bof the second hole261.

On the lens barrel11A side, the large diameter shaft66aof the shaft member66is inserted into the opposing hole portion93of the second hole261. On the lens barrel11B side, the shaft portion65bof the shaft member65is inserted into the opposing hole portion93of the second hole261. The virtual circle indicated by a two-dot chain inFIG. 39is an incircle that internally contacts the four projections93bof the opposing hole portion93. That is, each of the shaft portion65band the large diameter shaft66a(the base end section66d) of the shaft member65has a diameter of the circle. In this contact state, each of the shaft portion65band the large diameter shaft66a(the base end section66d) is lightly press-fitted into the opposing hole portion93. That is, the distance between the opposed planes93bis slightly smaller than the diameter of the shaft portion65band the base end section66dat the initial state. The shaft portion65band the large diameter shaft66a(the base end section66d) contact each of the planes93bin a linear region along the axial direction of the second hole261. Neither the shaft portion65bnor the large diameter shaft66acontacts the cylindrical portion93a. Accordingly, the contact area of the opposing hole portion93contacting the shaft portion65band the large diameter shaft66a(the base end section66d) is reduced, and thus a load imposed by insertion of the shaft portion65band the large diameter shaft66a(the base end section66d) is reduced. Further, such a configuration that includes the plurality of planes93breduces or prevents tilting of the shaft portion65a, and also advantageously advances the shaft portion65band the large diameter shaft66ainside the second hole261in the axial direction.

FIGS. 41 and 42are illustrations of a positioning mechanism according to the third variation of an embodiment of the present disclosure. In the third variation of the embodiment, the first hole360has an opposing hole portion94as a substitute for the circular hole60aaccording to the above-described embodiment, and the second hole361has an opposing hole portion95as a substitute for the circular hole61aaccording to the above-described embodiment.

The opposing hole portion94of the second hole360has four planes94a. The four planes94aare provided at substantially the same positions as those of the four planes92bof the opposing hole portion92according to the second variation, and also formed in the same directions as those of the planes92baccording to the second variation. The third variation differs from the second variation (the opposing hole portions92) in that the corner portion (including a gentle chamfered shape) is formed between two adjacent planes94ain the third variation. In other words, the opposing hole portion92according to the second variation and the opposing hole portion94according to the third variation are common in terms of a rectangular hole shape defined by four planes.

As illustrated inFIG. 41, on the lens barrel HA side, the shaft portion65aof the shaft member65is press-fitted into the opposing hole portion94of the first hole360and internally contacts the four planes94b. Accordingly, a stable insertion of the shaft member is performed with a less load on the holes. Further, on the lens barrel11B side, each plane94bof the opposing hole portion94does not hamper the insertion of the small diameter shaft66binto the first hole360.

The opposing hole portion95of the second hole361has four planes95a. The four planes95aare provided at substantially the same positions as those of the four planes93bof the opposing hole portion93according to the second variation, and also formed in the same directions as those of the planes93baccording to the second variation. The third variation differs from the second variation (the opposing hole portions92) in that the corner portion (including a gentle chamfered shape) is formed between two adjacent planes95ain the third variation. In other words, the opposing hole portion93according to the second variation and the opposing hole portion95according to the third variation are common in terms of a rectangular hole shape defined by four planes.

As illustrated inFIG. 41, on the lens barrel11A side, the large diameter shaft66a(the base end section66d) of the shaft member65is press-fitted into the opposing hole portion95of the second hole361and internally contacts the four planes95a. On the lens barrel11B side, the shaft portion65bof the shaft member65is is press-fitted into the opposing hole portion95of the second hole361and internally contacts the four planes95a. Each of the shaft portion65band the large diameter shaft66acan be stably inserted into the opposing hole portion95with a less load.

FIGS. 43 and 44are illustrations of a positioning mechanism according to the fourth variation of an embodiment of the present disclosure. In the fourth variation of the embodiment, the first hole460has an opposing hole portion96as a substitute for the circular hole60aaccording to the above-described embodiment, and the second hole461has an opposing hole portion97as a substitute for the circular hole61aaccording to the above-described embodiment.

The opposing hole portion96of the first hole460includes a cylindrical portion96ahaving a cylindrical inner surface, and three planes96beach of which partially short-circuits the inner surface of the cylindrical portion96a. Each plane96bhas a planar shape that extends along the axial direction of the first hole460. The three planes96bare disposed at substantially equal angular intervals (120° intervals) in the circumferential direction around the axis of the first hole460. In other words, the opposing hole portion96has a substantially triangle shape inside defined by three surrounding planes96b. One of the three planes96b, which is disposed at the upper part along the up-to-down direction, is substantially parallel to the plane60cof the elongated hole60b, and is disposed farther (on the outer diameter side) from the center of the first hole460than the elongated hole60bdoes. The remaining two planes96bare slanted at the same angle in opposite directions relative to the plane60cof the elongated hole60b.

On the lens barrel11A side, the shaft portion65aof the shaft member65is inserted into the opposing hole portion96of the first hole460. The virtual circle indicated by a two-dot chain inFIG. 43is an incircle that internally contacts the three planes96bof the opposing hole portion96. That is, the shaft portion65aof the shaft member65has a diameter of the circle. In this contact state, the shaft portion65ais lightly press-fitted into the opposing hole portion96. The shaft portion65acontacts each of the planes962bin a linear region along the axial direction of the first hole460. The shaft portion65adoes not contact each of the cylindrical portion96a. Accordingly, the contact area between the shaft portion65aand the opposing hole portion96is reduced, and thus a load imposed by insertion of the shaft portion65ais reduced as compared to the configuration in which substantially the entire outer surface of the shaft portion65acontacts the inner surface of the hole. Further, such a configuration that includes the plurality of planes96breduces or prevents tilting of the shaft portion65a, and also advantageously advances the shaft portion65ainside the first hole460in the axial direction.

On the side of the lens barrel11B side, the small diameter shaft66bof the shaft member66is inserted into the first hole460. In the opposing hole portion96, the space surrounded by three planes96bhas a larger diameter than the small diameter shaft66b(the base end section66fand the tip section66g) does, which prevents each plane96bfrom hampering insertion of the small diameter shaft66binto the first hole460.

Same as the opposing hole portion96of the first hole460, the opposing hole portion97of the second hole461includes a cylindrical portion97ahaving a cylindrical inner surface, and three planes97beach of which partially short-circuits the inner surface of the cylindrical portion97a. The shape (inner diameter) of the cylindrical portion97aand the arrangement and shape of each plane97bare the same as those of the cylindrical portion96aand each plane96bof the opposing hole portion96. The three planes97bare disposed at substantially equal angular intervals (120° intervals) in the circumferential direction around the axis of the second hole461. When viewed along the axis of the second hole461, all of the cylindrical portion97aand the three planes97bare located outside the small diameter hole61bof the second hole461(seeFIG. 43).

On the lens barrel11A side, the large diameter shaft66aof the shaft member66is inserted into the opposing hole portion97of the second hole461. On the lens barrel11B side, the shaft portion65bof the shaft member65is inserted into the opposing hole portion97of the second hole461. The virtual circle indicated by a two-dot chain inFIG. 43is an incircle that internally contacts the three planes97bof the opposing hole portion97. That is, each of the shaft portion65band the large diameter shaft66a(the base end section66d) of the shaft member65has a diameter of the circle. In this contact state, each of the shaft portion65band the large diameter shaft66a(the base end section66d) is lightly press-fitted into the opposing hole portion97. The shaft portion65band the large diameter shaft66a(the base end section66d) contact each of the planes97bin a linear region along the axial direction of the second hole461. Neither the shaft portion65bnor the large diameter shaft66acontacts the cylindrical portion97a. Accordingly, the contact area of the opposing hole portion97contacting the shaft portion65band the large diameter shaft66a(the base end section66d) is reduced, and thus a load imposed by insertion of the shaft portion65band the large diameter shaft66a(the base end section66d) is reduced. Further, such a configuration that includes the plurality of planes93breduces or prevents tilting of the shaft67b, and also advantageously advances the shaft portion65band the large diameter shaft66ainside the second hole461in the axial direction.

In the first to fourth variations (FIGS. 37 to 44), each of the opposing hole portions (90,91,92,93,94,95,96,97) provided in the first holes (160,260,360,460) and the second holes (161,261,361,461) is a non-circular hole having inside a plurality of contacts (the protrusions90band91b, and planes92b,93b,94a,95a,96b, and97b) on the same virtual circle (the outer periphery of the shafts65aand65band the base end section66dof the large diameter shaft66a, indicated by two-dotted chain lines inFIG. 37). The shafts65aand65bof the shaft member65and the base end section66dof the large diameter shaft66aof the shaft member66are supported in contact with the plurality of contacts of each non-circular hole. As can be understood from these variations, the main-reference positioning mechanism according to the embodiments of the present disclosure may have a configuration in which each contact of the hole and the shaft has a non-cylindrical surface.

In the above-described embodiments and variations, the shapes of the opposing hole portions of the first hole and the second hole are the same, but the internal shapes of the opposing hole portion of the first hole and the opposing hole portion of the second hole may be different from each other. For example, the circular hole60aof the above-described embodiment may be used as the opposing hole portion of the first hole, and one of the opposing hole portions91,93,95, and97of the above-described variations may be used as the opposing hole portion of the second hole. In this case, the shaft member65and the shaft member66of the above-described embodiments may be used as is as long as the diameter of the virtual circle inscribed in the inner surface of the hole is set to be the same between the circular hole60aand the opposing hole portions91,93,95, and97.

The present disclosure is not limited to the above-described embodiments and variations, and numerous additional and variations are possible in light of the above teachings. For example, in the above-described embodiments, the large diameter shaft66aand the small diameter shaft66b, which constitute the sub-reference positioning mechanism, are partially different in diameter from each other (the large diameter shaft66aincludes the base end section66dand the tip section66e, and the small diameter shaft66bincludes the base end section66fand the tip section66g). It is also possible to provide a similar structure to the shaft member65constituting the positioning mechanism on the main reference side. The configurations according to the above-described embodiments causes the shaft members65and66to be press-fitted into the first hole60(160,260,360,460) and the second hole61(161,261,361,461), which achieves a stable support for the lens barrels11A and11B and prevents rattling of the lens barrels11A and11B. Particularly, the flange65cof the shaft member65and the flange66cof the shaft member66are not disposed between the lens barrel11A and the lens barrel11B, so as not to hamper the positioning in the front-to-back direction using the contact surfaces50and51. Accordingly, the shaft members65and66can be press-fitted into the first hole60(160,260,360,460) and the second hole61(161,261,361,461). Further, in addition to the press-fitting, the shaft members65and66may be fixed to the first hole60(160,260,360,460) and the second hole61(161,261,361,461) by a fixing member such as adhesive.

In the above-described embodiments and variations (FIGS. 37 to 44), a plurality of configurations of the first hole and the second hole into which the shaft member65and the shaft member66are inserted are described. In some other embodiments, the first hole and the second hole may have other different shapes. For example, the first hole and the second hole may have a polygonal shape (hexagonal or the like) whose internal shape is other than triangle or square.

The embodiments of the present disclosure are particularly effective in an imaging apparatus in which two imaging units to be combined have the identical shape. In the above-described embodiments, the lens barrel11A and the lens barrel11B have the identical shape, and the base frames12of the lens barrel11A and the lens barrel11B also has the identical shape. However, the embodiments of the present disclosure are applicable in optical systems in which two holders (the base frames12) holding two optical systems have different shapes and configurations.

In the composite lens barrel10according to an embodiment of the present disclosure, the optical axis X1of the lens barrel11A and the optical axis X1of the lens barrel11B are arranged coaxially. The configuration according to an embodiment of the present disclosure may be applied to an optical system in which the optical axes of incident light from an object in the optical systems are not coaxially arranged as long as the two optical systems are disposed symmetrically.

In the above-described embodiments and variations, cases in which two lens barrels11A and11B including the wide-angle lens systems A and B and the image sensors AI and BI (two imaging units) are combined are described. The optical system according to the embodiments of the present disclosure may be applied to a configuration that positions two holders by using the contact surfaces without the image sensors AI and BI disposed in the lens barrels11A and11B (that is, the image sensors AI and BI are separate from the optical system).

In the above-described embodiments, the composite lens barrel10or the imaging apparatus80generate a spherical image. However, no limitation is intended thereby, and an image obtained by the optical systems may be an image other than a spherical image, such as a panoramic image obtained by photographing 360 degrees only in a horizontal plane.