JP2013113986A - Lens unit and assembling method for lens unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove the eccentricity of a lens due to an assembly error with respect to a lens holding frame and to facilitate assembly in a lens unit and an assembling method for a lens unit.SOLUTION: A lens unit 1 comprises a first lens 2, a second lens 3, and a lens holding frame 7. The lens holding frame 7 comprises: a mirror frame 4 provided with a tapering face 4b that has a fixed taper angle θ; and collars 5, each of which has a lens holding surface 5b that holds a tapering face 5a having the taper angle θ on the outer circumference side, and holds lens side surfaces 2f and 3f on the inner circumferential side. The mirror frame 4 is provided with a lens receiving part 4c that receives one end side of the first lens 2 in the direction of an optical axis. Between the mirror frame 4 and the lens side surfaces 2f and 3f whose one end sides are received by the lens receiving part 4c, the collar 5 is fitted such that the tapering face 5a follows the tapering face 4b, and the lens holding face 5b follows the lens side surfaces 2f and 3f.

Description

  The present invention relates to a lens unit and a method for assembling the lens unit.

Conventionally, when a lens is used in an optical device, a lens unit in which the lens is held is configured in a lens holding frame having an attachment reference, and this lens unit is attached in the apparatus of the optical device.
In such a lens unit, a holding hole for inserting a lens is provided in the lens holding frame, and the lens is inserted into the holding hole, and then the position in the optical axis direction is positioned. The position of is fixed.
In order to smoothly perform this assembling operation, it is necessary to provide a radial gap between the lens and the holding hole, and therefore, there is a possibility that an eccentricity equal to the gap amount at maximum occurs. When a plurality of lenses are used, the same eccentricity may occur in each lens.
Therefore, when there is a possibility that eccentricity that affects the imaging performance may occur, the eccentricity adjustment work is performed before the lens is fixed.
On the other hand, various lens units in which the eccentricity adjustment is not adjusted have been proposed.
For example, Patent Document 1 discloses a lens unit that secures a predetermined air interval by directly adhering side surfaces of peripheral portions that do not affect the imaging action of a plurality of lenses, either directly or indirectly via an interposition member. A lens unit is described in which the lenses or the lens and the interposition member are cured with a fluid or a semi-fluid, and an outer peripheral surface is wrapped with an elastic material.
The material having elasticity described in Patent Document 1 is an elastic film, and specifically, adhesives and paints are mentioned.
Further, in Patent Document 2, an arcuate tapered surface inclined with respect to the optical axis is provided on the outer peripheral side of the lens region of one lens, and one lens is provided on the outer peripheral side of the lens region of the other lens. There is described a lens unit that is fixedly connected in a state where a raised protrusion-shaped portion that abuts on the tapered surface is provided, and eccentricity is removed by bringing the arcuate tapered surface and the raised protrusion-shaped portion into contact with each other.
In the lens unit of Patent Document 1, only the first lens contacts the lens barrel (lens holding frame).

Japanese Utility Model Publication No. 62-118213 JP 2009-163120 A

However, the above conventional lens unit has the following problems.
When fixing the lens to the lens holding frame without adjusting the eccentricity, the gap between the holding hole and the lens side surface must be less than the allowable eccentricity limit, so the lens holding frame and the lens side surface are processed with high accuracy. There is a need. Further, since the gap is reduced, it takes time to insert the lens, and the assembly time is increased. For this reason, there exists a problem that manufacturing cost will increase.
The technique described in Patent Document 1 is a technique in which lenses are brought into contact with each other, an air interval is set, and an outer shape is aligned and bonded and fixed, and a lens holding frame is not used. Since the lens unit of Patent Document 1 is held by an elastic member formed of an adhesive or the like on the outer peripheral portion, a lens unit that can be positioned with high accuracy with respect to an optical device as in the case of including a lens holding frame is provided. There is a problem that it cannot be obtained.
Although it is possible to assemble the lens joined body, which is the lens unit of Patent Document 1, in the lens holding frame, there is a problem that the eccentricity due to the gap between the lens holding frame and the lens joined body cannot be removed.
Further, although the technique described in Patent Document 2 eliminates the decentration between lenses within the range of processing accuracy of the lens, the first lens and the lens are used when assembling the fixedly connected lens assembly to the lens holding frame. There is a problem that the eccentricity due to the gap between the holding frame and the holding frame cannot be removed.
Further, in order to remove the eccentricity between the lenses, the arc-shaped tapered surface and the raised protrusion shape portion are essential, so that the shape becomes complicated, for example, a shape that cannot be formed by a glass polishing lens. is there.
In addition, since the arcuate tapered surface and the raised protrusion-shaped portion need to be provided on the outer peripheral side of the lens region, the outer diameter of the lens is increased compared to the case where these are not provided, the component cost is increased, and the size is reduced. There is a problem that it is not suitable.

  The present invention has been made in view of the above problems, and provides a lens unit and a lens unit assembling method that can be easily assembled while removing the eccentricity of the lens due to an assembling error with respect to the lens holding frame. With the goal.

  In order to solve the above problems, a lens unit of the present invention includes a lens and a lens holding frame that holds the lens inside, and the lens holding frame has a tapered hole portion having a certain taper angle. An outer holding member provided; an inner holding member having a tapered surface portion having a taper angle equal to the taper angle on the outer peripheral side and a cylindrical surface portion for holding the lens side surface of the lens on the inner peripheral side; The holding member or the inner holding member is provided with a lens receiving portion that receives one end side of the lens in the optical axis direction, and one end side in the optical axis direction is received by the lens receiving portion and the lens side surface and the outer side Between the holding member, the inner holding member is fitted so that the tapered surface portion follows the tapered hole portion and the cylindrical surface portion follows the lens side surface. To.

  In the lens unit of the present invention, the inner holding member may have a cut that penetrates between both end portions in the axial direction, and the inner peripheral length of the cylindrical surface portion may be equal to or less than the outer peripheral length of the lens. is there.

  In the lens unit according to the aspect of the invention, the lens may include a lens group including one or more lens pairs in contact with each other in the optical axis direction.

  In the lens unit of the present invention, the lens may include a plurality of lenses having different outer diameters, and a plurality of the cylindrical surface portions may be provided corresponding to the outer diameters of the plurality of lenses. is there.

  The lens unit assembling method of the present invention is an assembling method of a lens unit for holding a lens inside a lens holding frame, and the lens holding frame is held outside provided with a tapered hole portion having a certain taper angle. A member, and an inner holding member having a taper surface portion having a taper angle equal to the taper angle on the outer peripheral side and a cylindrical surface portion holding the lens side surface of the lens on the inner peripheral side, and the outer holding member or the inner inner member The holding member is provided with a lens receiving portion that receives one end side of the lens in the optical axis direction, and the lens unit is assembled by arranging the lens receiving portion at one end side in the optical axis direction of the lens. A front side of the outer holding member such that the inner holding member is positioned between a lens side surface of the lens disposed in the lens receiving portion and the outer holding member. An insertion step of inserting the inner holding member along the tapered surface portion along the tapered hole portion, and pushing the inner holding member so that the tapered surface portion follows the tapered hole portion and the cylindrical surface portion follows the lens side surface. A fitting step of fitting the inner holding member into the outer holding member; and a position fixing step of fixing a relative positional relationship between the inner holding member, the outer holding member, and the lens after the fitting step. And

  Further, in the lens unit assembling method of the present invention, the inner holding member has a cut that penetrates between both end portions in the axial direction, and in the inserting step, the inner diameter of the cylindrical surface portion of the inner holding member is The cut is spaced apart in the circumferential direction so as to be larger than the outer diameter of the lens, and in the fitting step, when the inner holding member is pushed in, the taper surface portion follows the taper hole portion, thereby causing the cut. It is possible to reduce the interval in the circumferential direction so that the cylindrical surface portion follows the lens side surface.

  According to the lens unit and the lens unit assembly method of the present invention, the inner holding member is inserted into the tapered hole portion of the outer holding member in the axial direction, and the inner holding member is fitted so that the tapered surface portion follows the tapered hole portion. By forming the holding frame, the cylindrical surface portion of the inner holding member follows the lens side surface, so that the lens can be easily assembled while removing the eccentricity of the lens due to an assembly error with respect to the lens holding frame.

It is a typical section showing an example of a lens unit of a 1st embodiment of the present invention. FIG. 2 is a schematic front view of a first lens of the lens unit according to the first embodiment of the present invention and a side view of the A view thereof. FIG. 4 is a schematic front view of a second lens of the lens unit according to the first embodiment of the present invention and a side view of the second view thereof. It is a typical sectional view of the outside holding member of the lens unit of a 1st embodiment of the present invention, and the side view of the C view. It is typical sectional drawing of the inner side holding member of the lens unit of the 1st Embodiment of this invention, its side view of D view, and EE sectional drawing in the side view of D view. It is typical process explanatory drawing explaining the assembly process of the lens unit of the 1st Embodiment of this invention. It is typical sectional drawing of the inner side holding member used for the lens unit of the 1st modification of the 1st Embodiment of this invention, the side view of the E view, and operation | movement explanatory drawing. It is typical sectional drawing of the inner side holding member used for the lens unit of the 2nd modification of the 1st Embodiment of this invention, the side view of the F view, and operation | movement explanatory drawing. It is a typical fragmentary sectional view of the lens unit of the 3rd modification of the 1st Embodiment of the present invention. It is a typical section showing an example of a lens unit of a 2nd embodiment of the present invention. It is a typical sectional view of the inner side holding member used for the lens unit of a 2nd embodiment of the present invention, and its G side view. It is a typical sectional view of the outside holding member used for the lens unit of a 2nd embodiment of the present invention, and its H side view. It is a typical cross section which shows the modification (4th modification) of the lens unit of the 2nd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In all the drawings, even if the embodiments are different, the same or corresponding members are denoted by the same reference numerals, and common description is omitted.

[First Embodiment]
The lens unit according to the first embodiment of the present invention will be described.
FIG. 1 is a schematic cross-sectional view showing an example of a lens unit according to the first embodiment of the present invention. FIG. 2A is a schematic front view of the first lens of the lens unit according to the first embodiment of the present invention. FIG.2 (b) is a side view of the A view in Fig.2 (a). FIG. 3A is a schematic front view of the second lens of the lens unit according to the first embodiment of the present invention. FIG. 3B is a side view as viewed from B in FIG. FIG. 4A is a schematic cross-sectional view of the outer holding member of the lens unit according to the first embodiment of the present invention. FIG. 4B is a side view as seen from C in FIG. Fig.5 (a) is typical sectional drawing of the inner side holding member of the lens unit of the 1st Embodiment of this invention. FIG.5 (b) is a side view of the D view in Fig.5 (a). FIG.5 (c) is EE sectional drawing in FIG.5 (b).

  As shown in FIG. 1, the lens unit 1 of the present embodiment includes a first lens 2 (lens), a second lens 3 (lens), a lens frame 4 (outer holding member), and a collar 5 (inner holding member). Prepare.

The first lens 2 is one of a pair of lenses held by the lens unit 1. In the present embodiment, as shown in FIGS. 2A, 2 </ b> B, and 2 </ b> C, the first lens having a convex surface is used. This is a meniscus lens having a surface 2a and a second lens surface 2b made of a concave surface, and a flange portion 2c provided on the outer peripheral side.
The positive / negative of the refractive power of the first lens 2 can be appropriately set according to the design specifications based on the application of the lens unit 1.

The outer shape of the flange portion 2c is an optical axis O ₂ circular diameter D ₂ centered on, a lens side surface 2f, the first flange surface 2d, and a second flange surface 2e.
Lens side 2f is a cylindrical surface with a diameter D ₂ that is formed so as to be coaxial with the optical axis O _2, in the radial direction for positioning in a direction intersecting the first lens 2 to the optical axis O ₂ It constitutes the reference plane.
The first flange surface 2d is the first lens surface 2a side of the flange portion 2c, a plan that is provided so as to be perpendicular to the optical axis O _2, between the outer periphery of the first lens surface 2a to the lens side surface 2f Is formed. The first flange surface 2d is formed in the direction along the optical axis O ₂ spaced apart by a predetermined distance from the vertex of the first lens surface 2a located.
Therefore, the first flange surface 2d, the positioning of the optical axis O ₂ in along the first lens in the direction 2 constitutes a reference surface as possible.
The second flange surface 2e is the second lens surface 2b side of the flange portion 2c, a plan that is provided so as to be perpendicular to the optical axis O _2, between the outer periphery of the second lens surface 2b to the lens side surface 2f Is formed.
On the second flange surface 2e, as shown in FIG. 2B, the circumference of the diameter d ₂ (where d ₂ <D ₂ ) around the optical axis O ₂ is equally divided in the circumferential direction 3 Protrusions 2g are provided at the positions.
The tip of the projecting direction of the protrusions 2g is perpendicular to the optical axis O _2, are aligned in spaced apart virtual plane from a distance set in advance the first flange surface 2d. Hereinafter, the distance to the tip of the protrusions 2g referred flange width w ₂ from the first flange surface 2d.
For this reason, the virtual plane on which the protrusions 2g are aligned is separated from the surface top of the first lens surface 2a and the surface top of the second lens surface 2b by a predetermined distance.
Therefore, the protrusions 2g are positioned in the optical axis O ₂ in along the first lens in the direction 2 constitute a reference protrusion possible.

The second lens 3 is the other of the pair of lenses held by the lens unit 1. In the present embodiment, as shown in FIGS. 3A, 3 </ b> B, and 3 </ b> C, the first lens made of a concave surface is used. This is a meniscus lens having a surface 3a and a second lens surface 3b made of a convex surface, and a flange portion 3c provided on the outer peripheral side.
The positive / negative of the refractive power of the second lens 3 can be appropriately set according to the design specifications based on the application of the lens unit 1.

The outer shape of the flange portion 3c is circular with a diameter D ₃ around the optical axis O _3, and includes a lens side surface 3f, the first flange surface 3d, and a second flange surface 3e.
Lens side 3f is a cylindrical surface with a diameter D ₃ that is formed so as to be coaxial with the optical axis O _3, in the radial direction for positioning in a direction intersecting the second lens 3 to the optical axis O ₃ It constitutes the reference plane.
In the present embodiment, the diameter D ₃ of the lens side surface ₃ f matches the diameter D ₂ of the lens side surface 2 f of the first lens 2.

The first flange surface 3d is the first lens surface 3a side of the flange portion 3c, a plan that is provided so as to be perpendicular to the optical axis O _3, between the outer periphery of the first lens surface 3a to the lens side surface 3f Is formed. The first flange surface 3d is formed in the direction along the optical axis O ₃ spaced apart by a predetermined distance from the vertex of the first lens surface 3a position.
Therefore, the first flange surface 3d is positioned in the second lens 3 in the direction along the optical axis O ₃ constitutes a reference surface as possible.
In the present embodiment, the first flange surface 3d is in contact with each protrusion 2g of the first lens 2 in the assembled state shown in FIG. Thus, a first lens surface 3a of the second lens 3, with the inter-plane distance between the second lens surface 2b of the first lens 2 can be kept constant, the optical axis O ₃ of the optical axis O ₂ They can be kept parallel to each other.

The second flange surface 3e is the second lens surface 3b side of the flange portion 3c, a plan that is provided so as to be perpendicular to the optical axis O _3, between the outer periphery of the second lens surface 3b to the lens side surface 3f Is formed.
On the second flange surface 3e, as shown in FIG. 3B, the circumference of the diameter d ₃ (where d ₃ <D ₃ ) centered on the optical axis O ₃ is equally divided in the circumferential direction. Protrusions 3g are provided at the positions.
The tip of the projecting direction of the protrusions 3g is perpendicular to the optical axis O _3, are aligned in spaced apart virtual plane from a distance set in advance the first flange surface 3d. Hereinafter, a distance from the first flange surface 3d to the tip of the protrusions 3g referred flange width w _3.
For this reason, the plane on which the protrusions 3g are aligned is separated from the top of the first lens surface 3a and the top of the second lens surface 3b by a predetermined distance.
Therefore, the protrusions 3g are positioned in the second lens 3 in the direction along the optical axis O ₃ constitute a reference protrusion possible.

  In the present embodiment, both the first lens 2 and the second lens 3 having such a configuration are manufactured by molding a synthetic resin.

As shown in FIG. 1, the lens frame 4 is a substantially cylindrical member that accommodates the first lens 2, the second lens 3, and the collar 5 therein and covers at least the lens side surfaces 2f and 3f from the side. is there.
As shown in FIGS. 4A and 4B, the shape of the lens frame 4 is such that the outer diameter of the outer peripheral surface is a diameter D _4e centered on the central axis P, and the surface of the outer peripheral surface has a central axis P and A male screw portion 4e aligned coaxially is formed.
In the present embodiment, the lens frame 4 is a member constituting the outermost periphery of the lens unit 1. Therefore, by providing a female screw portion that is screwed into the male screw portion 4e in an optical device or the like to which the lens unit 1 is assembled, the male screw portion 4e is used to attach the lens unit 1 to the optical device, or the optical axis of the lens unit 1 It is possible to adjust the position of the direction.
At this time, the central axis P of the lens frame 4 constitutes the unit central axis of the lens unit 1.

On one end side in the axial direction of the lens frame 4 (on the left side in FIG. 4A), a lens receiving portion 4c that protrudes over the entire circumference toward the center portion is formed.
A circular opening 4f centering on the central axis P is formed at the tip of the lens receiving portion 4c in the protruding direction. The opening diameter D 4f of the opening _4f is larger than the outer diameter of the first lens surface 2a of the first lens 2, so that the first lens surface 2a can be inserted in the assembled state of the first lens 2. Yes (see FIG. 1).
The lens receiving portion 4c has a conical inclined surface 4g which is inclined toward the other end side in the axial direction from the outer peripheral side toward the central portion on one end side in the axial direction, and is centered on the other end side in the axial direction. It has an inner side surface 4h consisting of a plane orthogonal to the axis P.
Further, as shown in FIG. 4B, the lens receiver 4c has a diameter d ₁ (where D _4f <d ₁ <D ₂ ) around the central axis P on the inner surface 4h. Protrusions 4d are formed at three locations equally divided in the circumferential direction.
The tips in the protruding direction of the protrusions 4d are aligned with a virtual plane orthogonal to the central axis P. In the present embodiment, each protrusion 4 d constitutes a reference protrusion that positions the first lens 2 in the direction along the central axis P.

  As shown in FIG. 4A, the taper surface 4b (from the inner side surface 4h toward the other end in the axial direction is provided on the inner peripheral portion of the lens frame 4 on the other end side in the axial direction from the lens receiving portion 4c. A tapered hole portion) and an insertion guide surface 4a are formed in this order.

The tapered surface 4b has a conical shape centered on the central axis P, and is formed from the inner side surface 4h to the position of the intermediate portion in the axial direction of the lens frame 4.
The inner diameter of the tapered surface 4b has an inner diameter larger than the outer diameter of the first flange surface 2d of the first lens 2 at the position of the inner surface 4h, and has a constant taper angle θ toward the other end side in the axial direction. The diameter is expanded at a rate.
Length along the center axis P of the tapered surface 4b is set to be longer than the sum of the flange width w ₂ and the flange width w ₃ of the second lens 3 of the first lens 2 (w 2 _{+ w 3)} Yes.

The insertion guide surface 4a is a cylindrical surface centered on the central axis P, and has a diameter _D4a (where _D4a < _D4e ) larger than the inner diameter of the tapered surface 4b. The insertion guide surface 4 a forms a circular opening at the other end of the lens frame 4.
In this embodiment, the length of the insertion guide surface 4a in the axial direction is such that the top of the second lens surface 3b of the second lens 3 does not protrude outside the lens frame 4 in the assembled state, as shown in FIG. Set to dimensions.

  The material of the lens frame 4 is not particularly limited as long as the material has a strength that can withstand an external force generated when the collar 5 described later is pushed. For example, a metal such as aluminum or a synthetic resin having higher rigidity than the collar 5 described later can be used.

As shown in FIG. 1, the collar 5 is inserted into the first lens 2 and the second lens 3 and held in contact with the lens side surfaces 2 f and 3 f from the side. It is a substantially cylindrical member fitted inside the surface 4b.
The collar 5 is a member that is easily deformed when an external force is applied. The shape of the collar 5 is different between a natural state where the external force does not act and a state where the lens unit 1 is assembled and deformed (hereinafter referred to as an assembled state).

In the natural state, as shown in FIGS. 5A, 5B, and 5C, the collar 5 is an abbreviation in which the cross-sectional shape orthogonal to the central axis Q is a C shape lacking a part of the circumference. It is a cylindrical member. That is, the end face 5j penetrating in the axial direction and the thickness direction, 5k are opposed across a width t ₅ in the circumferential direction, these end faces 5j, slit 5h (cut) is formed by 5k on the sides.
Further, the inner peripheral portion of the collar 5 has a lens holding surface 5b (cylindrical surface portion) formed in a cylindrical surface shape, and the outer peripheral portion has a taper angle θ and one end side in the axial direction of the collar 5 (FIG. 5 ( a) It has a tapered surface 5a (tapered surface portion) whose diameter decreases toward the left side). A distal end surface 5 f made of a plane orthogonal to the central axis Q is formed at one end of the collar 5 in the axial direction.
Further, a flange portion 5c is provided at the other end in the axial direction of the collar 5 (the end portion on the right side of FIG. 5A) that protrudes toward the inner peripheral side of the lens holding surface 5b and the outer peripheral side of the tapered surface 5a. ing.
At the other end in the axial direction of the flange portion 5c, a rear end surface 5d made of a single plane orthogonal to the central axis Q is formed.
At one end in the axial direction of the flange portion 5c, a lens receiving surface 5i formed of a plane orthogonal to the central axis Q is formed inside the lens holding surface 5b.
Hereinafter, in the collar 5, one end in the axial direction (the front end surface 5 f side) is the front end of the collar 5, and the other end in the axial direction (the flange portion 5 c side) is the rear end of the collar 5. Called. Further, the wall-shaped portion sandwiched in the radial direction between the tapered surface 5 a and the lens holding surface 5 b is referred to as a fitting portion 5 m of the collar 5.

In the assembled state, as the opening width of the slit 5h is reduced, the outer diameter of the tapered surface 5a and the inner diameter of the lens holding surface 5b are reduced. For this reason, as shown in FIG. 1, the taper surface 5a is formed on the taper surface 4b in a state where the flange portions 2c and 3c are sandwiched between the projection 4d of the lens frame 4 and the lens receiving surface 5i. The lens holding surface 5b is deformed so as to follow the lens side surfaces 2f and 3f.
When the collar 5 is made of a material having lower rigidity and lower strength than the lens frame 4, the first lens 2, and the second lens 3, the collar 5 is elastically deformed or plastically deformed in the assembled state. It is also possible to do.

A flange outer peripheral surface 5e that is a cylindrical surface having a diameter D _5e (D _5e <D _4a ) is formed on the outer periphery of the flange portion 5c.
A flange inner peripheral surface 5g which is a cylindrical surface having a diameter D _5g (D _5g <D _5b ) is formed on the inner periphery of the flange portion 5c. The diameter D _5g of the flange inner peripheral surface 5g is larger than the outer diameter of the second lens surface 3b in the assembled state, and each protrusion 3g on the second flange surface 3e contacts the lens receiving surface 5i. Set the dimensions to allow contact.

Lens holding surface 5b has a diameter _{D 5b} around a central axis Q _{(however, D 2 <D 5b, D} 3 <D 5b) is a cylindrical surface of the formed in a range from the front end face 5f to the lens receiving surface 5i ing.
The axial length W _5b (see FIG. 5C) of the lens holding surface 5b is set to a dimension that satisfies the condition of w ₃ <W _5b <w ₂ + w ₃ . However, the length W _5b is preferably a value closer to w ₂ + w _{3 in} the above range.

Width t ₅ of the slit 5h, in addition to the above condition D _5b, the inner circumference of the lens holding surface 5b is a lens side surface 2f, are set to 3f a circumferential length less.
When the peripheral lengths of the lens side surfaces 2f and 3f are different due to a manufacturing error, the peripheral length is set to be shorter than the shorter one. This condition is always satisfied if the inner peripheral length of the lens holding surface 5b is set to be equal to or smaller than the minimum outer peripheral length of the permissible range of the peripheral lengths of the lens side surfaces 2f and 3f.

Tapered surface 5a, in the natural state, has a diameter _{D 5a} at a distal end face 5f.
Further, the length along the axial direction of the tapered surface 5 a is set to be longer than the length along the axial direction of the tapered surface 4 b of the lens frame 4.
The diameter _{D 5b} diameter _{D 5a} and lens holding surface 5b of the tapered surface 5a defines the thickness of the tip of the fitting portion 5 m. Therefore, the diameter D _5a of the tapered surface 5a, the thickness of the tip of the fitting portion 5m, and the axial cross-sectional shape of the fitting portion 5m determined by this and the taper angle theta (cross-sectional shape in a plane including the central axis line Q) is Decide from the shape to be filled.
As shown in FIG. 1, the cross-sectional shape in the axial direction to be filled by the fitting portion 5m is inserted between the lens side surfaces 2f and 3f of the first lens 2 and the second lens 3 and the tapered surface 4b, as shown in FIG. In a state where the first lens 2 and the second lens 3 are pressed and assembled in the optical axis direction by the lens receiving surface 5i of the collar 5, the tapered surface 5a follows the tapered surface 4b, and the lens holding surfaces on the lens side surfaces 2f and 3f. 5b is the shape to be copied.
Here, the taper surface 5a and the lens holding surface 5b "follow" the taper surface 4b and the lens side surfaces 2f and 3f, respectively, as a result of a change in the overall radial dimension due to a change in the interval between the slits 5h in the collar 5. The axial cross section formed between the lens side surfaces 2f and 3f and the tapered surface 4b is fitted in a wedge-shaped gap.
The tapered surface 4b and the tapered surface 5a, the lens side surfaces 2f and 3f, and the lens holding surface 5b are preferably in close contact with each other in the radial direction over the entire circumference. However, if the first lens 2 and the second lens 3 are positioned within the allowable limit of eccentricity with respect to the central axis P of the lens frame 4 by abutting in the radial direction without rattling, the first lens 2 and the second lens 3 are not necessarily fitted in close contact. There is no need to match. For example, due to error factors such as fine unevenness and roundness of each surface, a contact state in which a gap is generated partially can be allowed. In other words, it is only necessary to be able to fit in a substantially close contact state including the close contact state.
Further, when a material having rigidity and strength lower than that of the lens frame 4, the first lens 2, and the second lens 3 is used as the collar 5, the collar 5 is thicker than the wedge-shaped gap and elastic in the radial direction. You may make it fit in a press-fit state by deform | transforming or plastically deforming.

  The material of the collar 5 is not particularly limited as long as the material can be easily deformed by an external force received from the tapered surface 4b when the tapered surface 5a is pushed into the tapered surface 4b of the lens frame 4. For example, a metal such as aluminum or a synthetic resin having lower rigidity than the lens frame 4 can be used.

As will be described later, the bonding portion 6 is for fixing the collar 5 and the lens frame 4 after assembling the first lens 2, the second lens 3 and the collar 5 inside the lens frame 4. As shown in FIG. 1, the adhesive applied across the outer peripheral portion of the rear end surface 5d of the collar 5 and the insertion guide surface 4a of the lens frame 4 is cured.
The bonding portion 6 may be formed in an arc shape continuously between the outer peripheral portion of the rear end surface 5d and the insertion guide surface 4a in the circumferential direction, or is formed in a dotted state separated in the circumferential direction. May be.
As the adhesive forming the bonding portion 6, a type capable of obtaining a good bonding strength can be appropriately selected according to the materials of the collar 5 and the lens frame 4.
Examples of the adhesive suitable for the bonding portion 6 include an adhesive such as a UV curable adhesive, a two-component adhesive, and a thermosetting adhesive.

Next, the positional relationship among the first lens 2, the second lens 3, the lens frame 4, and the collar 5 in the lens unit 1 will be described with reference to FIG.
The first lens 2 is inserted in the taper surface 4b in the axial direction with the first lens surface 2a facing the opening 4f, and the first flange surface 2d contacts the projections 4d of the lens frame 4. It is touched.
The second lens 3 is inserted in the taper surface 4b and the insertion guide surface 4a in the axial direction with the first lens surface 3a facing the first lens 2, and the first flange surface 3d is each protrusion of the first lens 2. 3g is contacted.
A collar 5 is inserted between the lens side surface 2f of the first lens 2 and the lens side surface 3f of the second lens 3 and the insertion guide surface 4a of the lens frame 4 in the axial direction from the front end surface 5f side. 3 projections 3 g are in contact with the lens receiving surface 5 i of the collar 5.
Due to this positional relationship, the inter-surface distance between the second lens surface 2b and the first lens surface 3a is set to a preset inter-surface interval.

The tapered surface 5a of the collar 5 is in contact with the tapered surface 4b of the lens frame 4 without rattling in the radial direction. In the present embodiment, the taper surface 5a and the taper surface 4b are in close contact with each other, so that they are not rattling.
Further, the lens holding surface 5b of the collar 5 is in contact with the lens side surfaces 2f and 3f without rattling in the radial direction. In the present embodiment, the lens holding surface 5b is brought into close contact with the lens side surfaces 2f and 3f so as not to rattle.
Due to such a positional relationship, the optical axes O ₂ and O _{3 of} the first lens 2 and the second lens 3 and the central axis Q of the collar 5 are within the range of the eccentric error caused by the respective component processing errors, It is aligned with the central axis P of the frame 4.

  In such an assembled state, the bonding portion 6 fixes the collar 5 and the lens frame 4 to each other so that the first lens 2, the second lens 3, the lens frame 4, and the collar 5 can be positioned relative to each other. The relationship is fixed.

With such a configuration, the lens frame 4 constitutes an outer holding member provided with a tapered surface 4b which is a tapered hole portion having a constant taper angle θ.
The collar 5 is a cylindrical surface portion that holds a tapered surface 5a that is a tapered surface portion having a taper angle θ on the outer peripheral side and holds the lens side surfaces 2f and 3f of the first lens 2 and the second lens 3 on the inner peripheral side. The inner holding members each having the lens holding surface 5b are configured.
The assembly of the lens frame 4 and the collar 5 constitutes a lens holding frame 7 that holds the lens inside.
Further, in the present embodiment, the first lens surface 2 that is a pair of lenses constituting the lens and the first flange surface 2 d that is one end side of the second lens 3 are received by the lens receiving portion 4 c provided in the lens frame 4. ing.

Next, a method for assembling the lens unit 1 will be described.
FIGS. 6A and 6B are schematic process explanatory views illustrating the assembly process of the lens unit according to the first embodiment of the present invention.

  The lens unit 1 can be assembled by performing the lens placement process, the insertion process, the fitting process, and the position fixing process in this order.

First, a lens arrangement process is performed. In this step, the first lens 2 and the second lens 3 are overlapped so that the first flange surface 2d of the first lens 2 abuts on the protrusion 4d that is a lens receiving portion of the lens frame 4, and the lens frame It is a process of arrange | positioning in 4 taper surfaces 4b.
First, the first flange surface 2d of the first lens 2 is opposed to the protrusion 4d, the first lens 2 is inserted into the insertion guide surface 4a and the tapered surface 4b, and the first flange surface 2d is in contact with the protrusion 4d. Make contact. At this time, the center position of the first lens 2 may be deviated from the central axis Q, but there is a gap between the lens side surface 2f and the tapered surface 4b so that the tip of the collar 5 can be inserted over the entire circumference. Arrange to form.
Next, the second lens 3 is inserted into the insertion guide surface 4a and the tapered surface 4b with the first flange surface 3d of the second lens 3 opposed to the projection 2g of the first lens 2, and the first flange surface 3d. Is brought into contact with the protrusion 2g, and the second lens 3 is superimposed on the first lens 2. At this time, the center position of the second lens 3 may be deviated from the center axis Q, but there is a gap between the lens side surface 3f and the tapered surface 4b so that the tip of the collar 5 can be inserted over the entire circumference. Arrange to form.
This completes the lens placement process.

Next, an insertion process is performed. In this step, the collar 5b is placed along the tapered surface 4b so that the tip of the collar 5 is positioned between the lens side surfaces 2f and 3f disposed in the tapered surface 4b and the tapered surface 4b. 5 is a step of inserting 5.
In the present embodiment, the outer diameter D _5e of the flange outer peripheral surface 5e of the collar 5 in the natural state is smaller than the inner diameter D _4a of the insertion guide surface 4a that is an opening on the other end side of the lens frame 4, so that the collar 5 is natural. Even in this state, the outer peripheral surface 5e of the flange does not contact the entire insertion guide surface 4a.
The tapered surface 5a can be inserted without contacting the tapered surface 4b at the start of insertion, but when the tip of the collar 5 is inserted into the tapered surface 4b to some extent, FIG. 6 (a). As shown, the entire circumference of the tapered surface 5a is in contact with the tapered surface 4b.
At this time, color 5, so still a natural state, the inner diameter D ₅ is a second lens 3 of the lens holding surface 5b, it is larger than the outer diameter D _2, D ₃ of the first lens 2, the radial clearance It has (refer Fig.6 (a)). For this reason, however, the optical axes O ₂ and O ₃ are not necessarily aligned with the central axis Q of the collar 5.
This is the end of the lens insertion process.

Next, a fitting process is performed. This step is a step of pressing the collar 5 and fitting the collar 5 into the lens frame 4 so that the tapered surface 4a follows the tapered surface 4b and the lens holding surface 5b follows the lens side surfaces 2f and 3f.
That is, from the state shown in FIG. 6A, the collar 5 is pushed in by applying a pressing force to the rear end surface 5 d of the collar 5. At this time, since the tapered surface 4b is reduced in diameter in accordance with the taper angle θ on the front end side in the pushing direction, a radial external force acts on the tapered surface 5a of the collar 5 to reduce the width of the slit 5h. For this reason, the diameter of the collar 5 is reduced as a whole.
At this time, since the collar 5 is a curved body having a C-shaped cross section as a whole, the tapered surface 5a of the collar 5 is deformed in an arc shape in which the cross section is coaxial with the central axis Q, following the shape of the tapered surface 4b. To do. For this reason, the lens holding surface 5b is also reduced in diameter while maintaining an arc shape whose cross section is coaxial with the central axis Q. Thereby, as the collar 5 is pushed in, the gap between the lens holding surface 5b and the lens side surfaces 2f and 3f is narrowed, and the first lens 2 and the second lens 3 are aligned with respect to the central axis Q.
As shown in FIG. 6B, when the lens receiving surface 5i of the collar 5 comes into contact with the protrusion 3g of the second lens 3, the pushing is stopped.
This is the end of the fitting process.

In this step, when the fitting portion 5m of the collar 5 is fitted in the gap between the lens side surfaces 2f and 3f and the tapered surface 4b, in the axial direction, each projection 4d, the first flange surface 2d, and each projection 2g and the first flange surface 3d, the projections 3g and the lens receiving surface 5i are in contact with each other, and the first lens 2, the second lens 3, and the collar 5 are axially positioned with respect to the lens frame 4. The
In the radial direction, the tapered surface 4b and the tapered surface 5a, and the lens holding surface 5b and the lens side surfaces 2f and 3f are substantially in close contact (including the case where they are in close contact with each other).

Next, a position fixing process is performed. This step is a step of fixing the relative positional relationship between the collar 5, the lens frame 4, the first lens 2, and the second lens 3 after the fitting step.
In the present embodiment, as shown in FIG. 1, an adhesive is applied between the outer peripheral portion of the rear end surface 5 d and the insertion guide surface 4 a and cured to form the adhesive portion 6. The adhesive may be applied in an arc shape or in a dotted state.
Thereby, since the collar 5 and the lens frame 4 are fixed, the relative positional relationship between the collar 5, the lens frame 4, the first lens 2, and the second lens 3 at the end of the fitting process is fixed.
Thus, the position fixing process is finished, and the assembly of the lens unit 1 as shown in FIG. 1 is finished.

  According to the lens unit 1 and the assembly method of the lens unit 1 of the present embodiment, the collar 5 that holds the lens side surfaces 2f and 3f with the lens holding surface 5b is pushed into and fitted into the tapered surface 4b of the lens frame 4, thereby A lens holding frame 7 is formed. For this reason, the diameter of the collar 5 is reduced during the fitting process so that the lens side surfaces 2f and 3f and the lens holding surface 5b are in close contact with each other, and the first lens 2 and the second lens 3 are aligned with the lens frame 4. Can be assembled into a finished state. As a result, it is possible to remove the decentering of the first lens 2 and the second lens 3 due to an assembly error with respect to the lens holding frame 7 and easily assemble.

[First Modification]
Next, a first modification of the present embodiment will be described.
Fig.7 (a) is typical sectional drawing of the inner side holding member used for the lens unit of the 1st modification of the 1st Embodiment of this invention. FIG.7 (b) is a side view of E view in Fig.7 (a). FIG. 7C is an explanatory view of the operation of the internal holding member of the present modification.

As shown in FIGS. 7A and 7B, the collar 45 (inner holding member) of this modification is a modification of the collar 5 in the lens unit 1 of the first embodiment. The color 5 can be used instead.
The collar 45 is obtained by adding an elastic deformation portion 45a that connects the facing distances of the end faces 5j and 5k so as to be reduced between the end faces 5j and 5k of the slit 5h of the collar 5.
The collar 45 is formed by integral molding with a low-rigidity synthetic resin that is easily elastically deformed.
The following description will focus on the differences from the collar 5 of the first embodiment.

The shape of the elastic deformation portion 45a in a natural state is a thin plate shape that extends along the circumferential direction between the end faces 5j and 5k. The axial position may be provided between the rear end surface 5d and the front end surface 5f, but in this modification, as an example, the axial position is provided near the rear end surface 5d.
For this reason, in the assembled state, when an external force that causes deformation that narrows the facing distance between the end faces 5j and 5k acts on the collar 45, the elastic deformation portion 45a undergoes buckling deformation in the circumferential direction as shown in FIG. As a result, the facing distance between the end faces 5j and 5k is reduced.
When such an external force disappears, the spacing between the end faces 5j and 5k increases due to the elastic restoring force of the collar 45 itself, and the shape of the elastic deformation portion 45a is restored to the natural state.
The thickness of the elastic deformation portion 45a in the radial direction is such that the circumferential length of the flange inner peripheral surface 5g is the first lens 2 and the second lens 3 when the opposing distance between the end surfaces 5j and 5k is minimized due to buckling deformation. It is set to be shorter than the outer circumference of the outer diameter.

With such a configuration, the collar 45 of the present modified example is reduced in diameter in the same manner as the collar 5 when inserted into the insertion gap between the first lens 2 and the second lens 3 and the tapered surface 4b. Therefore, it can be used for assembling the lens unit 1 in the same manner as in the first embodiment.
In the present modification, the end surfaces 5j and 5k are connected in the circumferential direction by the elastic deformation portion 45a. Therefore, when the diameter is reduced following the tapered surface 4b, the end surfaces 5j and 5k are restrained from moving in the axial direction. Therefore, for example, it is possible to prevent movement in the opposite directions in the axial direction. For this reason, since the shape at the time of pushing in can be stabilized more, pushing operation becomes easier.

[Second Modification]
Next, a second modification of the present embodiment will be described.
Fig.8 (a) is typical sectional drawing of the inner side holding member used for the lens unit of the 2nd modification of the 1st Embodiment of this invention. FIG. 8B is a side view as seen from F in FIG. FIG. 8C is an operation explanatory view of the internal holding member of the present modification.

As shown in FIGS. 8A and 8B, the collar 55 (inner holding member) of the present modification is a modification of the collar 5 in the lens unit 1 of the first embodiment. The color 5 can be used instead.
The collar 55 is a cylindrical member from which the slit 5 h of the collar 5 is deleted, and the cross section including the central axis Q of the collar 45 has the same shape as the cross section including the central axis Q of the collar 5.
The following description will focus on the differences from the collar 5 of the first embodiment.

The collar 55 corresponds to the tapered surface 5a of the collar 5, the lens holding surface 5b, the flange portion 5c, the flange outer peripheral surface 5e, the flange inner peripheral surface 5g, the lens receiving surface 5i, the front end surface 5f, and the rear end surface 5d, respectively. , A taper surface 55a, a lens holding surface 55b, a flange portion 55c, a flange outer peripheral surface 55e, a flange inner peripheral surface 55g, a lens receiving surface 55i, a front end surface 55f, and a rear end surface 55d. In the collar 55, a wall-shaped portion sandwiched in the radial direction between the tapered surface 55a and the lens holding surface 55b constitutes a fitting portion 55m.
The collar 55 is made of a low-rigidity synthetic resin that is easily elastically deformed or a low-strength metal that is easily plastically deformed.

The shape of the natural state of the collar 55, the outer diameter of the flange outer peripheral surface 55e, the inner diameter of the flange inner peripheral surface 55g is, the outer diameter _{D 5e} of each flange outer circumferential surface 5e, equal to the inner diameter _{D 5 g} of the flange inner circumferential surface 5g.
The axial length of the lens holding surface 55b, that is, the distance from the front end surface 55f to the lens receiving surface 55i is equal to the length W _5b of the lens holding surface 5b of the collar 5.
The inner diameter D ₅₅ of the natural state of the lens holding surface 55b, the first lens 2, than the outer diameter of the second lens 3 a large diameter, by elastic deformation or plastic deformation in the assembled state, the first lens 2, the It is set according to the rigidity and strength of the collar 55 so that it can be deformed to an inner diameter D ₅₅ ′ (see FIG. 8C) equal to the outer diameter of the two lenses 3.

  With such a configuration, the collar 55 of the present modification is reduced in diameter in the same manner as the collar 5 when it is pushed into the insertion gap between the first lens 2 and the second lens 3 and the tapered surface 4b. Therefore, it can be used for assembling the lens unit 1 in the same manner as in the first embodiment.

[Third Modification]
Next, a lens unit according to a third modification of the present embodiment will be described.
FIG. 9 is a schematic partial cross-sectional view of a lens unit of a third modified example of the first embodiment of the present invention.

As shown in FIG. 9, the lens unit 31 of the present modification includes a second lens 33 (lens) and a collar 35 (inner holding member) instead of the second lens 3 and the collar 5 of the first embodiment. Prepare.
Hereinafter, a description will be given centering on differences from the first embodiment.

The second lens 33 is obtained by reducing the outer diameter of the lens side surface 3f of the second lens 3 of the first embodiment with respect to the first lens 2, and the diameter D ₃₃ instead of the lens side surface 3f. (However, a lens side surface 33f made of a cylindrical surface of D ₃₃ <D ₂ ) is provided.

The collar 35 includes a first lens holding surface 35A (cylindrical surface portion) and a second lens holding surface 35B (cylindrical surface portion) instead of the lens holding surface 5b of the color 5. In the collar 35, a wall-like portion sandwiched in the radial direction by the tapered surface 5a, the first lens holding surface 35A, and the second lens holding surface 35B constitutes a fitting portion 35m.
The first lens holding surface 35A is different from the lens holding surface 5b only in that the length of the lens holding surface 5b in the axial direction is reduced to a length that covers the lens side surface 2f of the first lens 2 in the assembled state. Different. Accordingly, the inner diameter of the first lens holding surface 35A in the natural state is the same as the inner diameter D _5b of the lens holding surface 5b.
The second lens holding surface 35B is formed on the inner peripheral portion of the collar 35 between the end of the first lens holding surface 35A on the flange 5c side and the lens receiving surface 5i. It is a cylindrical surface concentric with the first lens holding surface 35A provided in a range covering the lens side surface 33f.
The inner diameter of the second lens holding surface 35B is set to a size obtained by subtracting the difference between the outer diameter of the first lens 2 and the outer diameter of the second lens 33 from the natural inner diameter D _{5b of} the first lens holding surface 35A. Has been.

The lens unit 31 configured as described above is assembled in substantially the same manner as in the first embodiment, except that the second lens 3 and the collar 5 in the first embodiment are replaced with the second lens 33 and the collar 35. be able to.
That is, in the lens arrangement process of this modification, when the second lens 33 is overlapped with the first lens 2, the lens side surface 33f is arranged so as to be substantially coaxial with the lens side surface 2f. The other insertion process, fitting process, and position fixing process are the same processes as in the first embodiment.
In this modification, in the insertion step, the first lens holding surface 35A is inserted in a state of surrounding the outer peripheral side of the lens side surface 2f and surrounding the outer peripheral side of the second lens holding surface 35B. In the fitting step, the first lens holding surface 35A is inserted into the tapered surface 4b. Similarly, as the diameter of the collar 35 is reduced, the first lens holding surface 35A and the second lens holding surface 35B are reduced in diameter, and are fitted in states that follow the lens side surface 2f and the lens side surface 33f, respectively.
Thus, this modification is an example in which the lens unit assembling method of the first embodiment can be applied even when the outer diameters are different from each other.
Such a lens unit 31 has the same effect as the lens unit 1.

[Second Embodiment]
A lens unit according to a second embodiment of the present invention will be described.
FIG. 10 is a schematic cross section showing an example of a lens unit according to the second embodiment of the present invention. Fig.11 (a) is typical sectional drawing of the inner side holding member used for the lens unit of the 2nd Embodiment of this invention. FIG.11 (b) is a side view of the G view in Fig.11 (a). FIG. 12A is a schematic cross-sectional view of an outer holding member used in the lens unit according to the second embodiment of the present invention. FIG.11 (b) is a side view of H view in Fig.11 (a).

As shown in FIG. 10, the lens unit 11 of the present embodiment replaces the lens frame 4, the collar 5, and the bonding portion 6 of the first embodiment with a collar 15 (outer holding member) and a lens frame 14, respectively. (Inner holding member) and adhesive portions 16a and 16b.
The second lens 3 will be described by using an example in which the same lens as that in the first embodiment is used. However, in the present embodiment, a configuration in which the protruding portion 3g is omitted is also possible.
Hereinafter, a description will be given centering on differences from the first embodiment.

The collar 15 is a substantially cylindrical member that accommodates the first lens 2, the second lens 3, and the lens frame 14 therein and covers at least the lens side surfaces 2f and 3f from the side.
As shown in FIGS. 11A and 11B, the collar 15 has an outer peripheral surface 15a having a diameter D _15b centered on the central axis R and coaxial with the central axis R on the inner peripheral side of the outer peripheral surface 15a. A conical tapered surface 15b (tapered hole portion) formed from one end side in the axial direction (left side in FIG. 11A) to the other end with a taper angle θ, and one axial end of the tapered surface 15b. And a stopper portion 15c protruding toward the inner peripheral side.
Diameter of the tapered surface 15b of the natural state in a position in contact with the stopper portion 15c has a diameter _{D 15b (although, D 2 <D 15b <D} 15a). Further, the inner peripheral surface 15f of the stopper portion 15c is a cylindrical surface having a diameter _D15f provided coaxially with the central axis R. The diameter D _15f is not particularly limited as long as it is smaller than D _15b and is outside the effective light beam diameter range of the optical system constituted by the first lens 2 and the second lens 3.

  In the present embodiment, the length along the central axis R of the tapered surface 15b is set to be longer than the axial length of the lens frame 14 described later.

In the present embodiment, the collar 15 is a member constituting the outermost periphery of the lens unit 11. Therefore, it is possible to attach the lens unit 11 to the optical device or adjust the position of the lens unit 11 using the outer peripheral surface 15a as a reference surface perpendicular to the optical axis in an optical device or the like to which the lens unit 1 is assembled. It is.
At this time, the central axis R of the collar 15 constitutes the unit central axis of the lens unit 11.
The material of the collar 15 can be the same material as that of the lens frame 4 of the first embodiment.

As shown in FIG. 10, the lens frame 14 is inserted into the first lens 2 and the second lens 3 and held in contact with the side surfaces 2 f and 3 f of the lens 15 from the side. It is a substantially cylindrical member fitted inside the surface 15b.
The lens frame 14 has a configuration in which the flange portion 5c of the collar 5 of the first embodiment is deleted and a structure substantially similar to the lens receiving portion 4c of the lens frame 4 is provided on the distal end surface 5f side. For this reason, like the collar 5 of the first embodiment, it is a member that is easily deformed when an external force is applied, and a natural state in which no external force is applied and a state in which the lens unit 11 is assembled and deformed (hereinafter referred to as the lens unit 11). , Referred to as an assembled state).

In the natural state, as shown in FIGS. 12 (a) and 12 (b), the lens frame 14 has a substantially cylindrical shape in which the cross-sectional shape orthogonal to the central axis S is a C shape lacking a part of the circumference. It is a member. That is, the end face extending in the axial direction and the thickness direction 14j, 14k are opposed across a width _{t 14} in the circumferential direction, these end faces 14j, slits 14h (cut) is formed by 14k on the side surface.

A lens receiving portion 14c is formed at one end of the lens frame 14 in the axial direction so as to protrude over the entire circumference toward the center.
A circular opening 14f centered on the central axis S is formed at the tip of the lens receiving portion 14c in the protruding direction. The opening diameter D 14f of the opening _14f is equal to the opening diameter of the opening 4f of the first embodiment.
A locking groove 14m is provided on the outer periphery of the lens receiving portion 14c so as to be locked with the stopper portion 15c of the collar 15 in the axial direction.
The lens receiving portion 14c has a conical inclined surface 14g which is inclined toward the other end side in the axial direction from the outer peripheral side toward the central portion on one end side in the axial direction, and is centered on the other end side in the axial direction. It has an inner side surface 14i made of a plane orthogonal to the axis S.
The lens receiving portion 14c, as shown in FIG. 12 (b), the same as the protrusion 4d of the first embodiment, on the inner side surface 14i, the circumference of diameter d ₁ with respect to the central axis S Projections 14d are formed at three locations that equally divide.
The tips of the protrusions 14d in the protruding direction are aligned with a virtual plane orthogonal to the central axis S. In the present embodiment, each protrusion 14 d constitutes a reference protrusion that positions the first lens 2 in the direction along the central axis P.

The lens frame 14 has a lens holding surface 14b (cylindrical surface portion) formed in a cylindrical shape from at least the protrusion 14d to the rear end surface 14e, which is the other end surface of the lens frame 14, on the inner peripheral portion of the lens frame 14.
The sum of the length _{W 14b} along the center axis S from the projecting portion 14d to the rear end surface 14e has a flange width _{w 2} and the flange width _{w 3} of the second lens 3 of the first lens 2 in the lens holding surface 14b _{(w 2} + W ₃ ).
Further, the outer peripheral portion of the lens frame 14 has a taper surface 14a (taper surface portion) whose diameter is reduced toward one end side (left side in FIG. 12A) of the lens frame 14 at a taper angle θ.
Hereinafter, in the lens frame 14, one end in the axial direction (the lens receiving portion 14 c side) is the tip of the lens frame 14, and the other end in the axial direction (the rear end surface 14 e side) is the end of the lens frame 14. This is called the rear end. Further, the wall-shaped portion sandwiched in the radial direction between the tapered surface 14 a and the lens holding surface 14 b is referred to as a fitting portion 14 m of the lens frame 14.

In the assembled state, as the opening width of the slit 14h is reduced, the outer diameter of the tapered surface 14a and the inner diameter of the lens holding surface 14b are reduced. For this reason, as shown in FIG. 10, the tapered surface 14a follows the tapered surface 15b of the collar 15 in a state where the flange portion 2c of the first lens 2 is received by the projecting portion 14d and the flange portions 2c and 3c are overlapped. The holding surface 14b is deformed so as to follow the lens side surfaces 2f and 3f.
When the lens frame 14 is made of a material having lower rigidity and lower strength than the collar 15, the first lens 2, and the second lens 3, the lens frame 14 is elastically deformed or plastically deformed in the assembled state. It is also possible to do.

Width _{t 14} of the slit 14h is set in the same manner as the width _{t 5} of the slit 5h of the first embodiment.
Lens holding surface 14b, the diameter _{D 14b} around the center axis S _{(however, D 2 <D 14b, D} 3 <D 14b) is a cylindrical surface. The diameter D _14b is equal to the diameter D _5b of the lens holding surface 5b of the first embodiment.
In the natural state, the tapered surface 14a has a diameter _D14a at a position in contact with the locking groove 14m.
The length of the tapered surface 14a along the axial direction is set to be longer than the length of the tapered surface 15b of the collar 15 along the axial direction.
The diameter _{D 14a} of the tapered surface 14a is in assembled state, so that it can accommodate the lens frame 14 on the tapered surface 15b on the collar 15, set as appropriate.

  The material of the lens frame 14 is not particularly limited as long as the material can be easily deformed by an external force received from the tapered surface 15b when the tapered surface 14a is pushed into the tapered surface 15b of the collar 15. The same material as that of the collar 5 of the first embodiment can be used.

As will be described later, the bonding portions 16a and 16b are arranged in such a manner that the first lens 2 and the second lens 3 are arranged inside the lens frame 14, and the lens frame 14 is fitted into the collar 15 and assembled. The relative positional relationship of the first lens 2, the second lens 3, and the collar 15 with respect to 14 is fixed.
The adhesive portion 16a fixes the second lens 3 and the lens frame 14, and is applied across the outer peripheral portion of the second flange surface 3e and the lens holding surface 14b of the lens frame 4 as shown in FIG. The adhesive is cured.
The adhesive portion 16b fixes the lens frame 14 and the collar 15, and is obtained by curing the adhesive applied across the outer peripheral portion of the rear end surface 14e of the lens frame 14 and the tapered surface 15b of the collar 15. .
The adhesive portions 16a and 16b may be formed in an arc shape continuously in the circumferential direction as in the adhesive portion 6 of the first embodiment, or are formed in a dotted state separated in the circumferential direction. It may be.
As the adhesive for forming the adhesive portions 16a and 16b, a type that can provide good adhesive strength can be appropriately selected according to the materials of the second lens 3, the lens frame 14, and the collar 15.
Examples of the adhesive suitable for the bonding portions 16a and 16 include an adhesive such as a UV curable adhesive, a two-component adhesive, and a thermosetting adhesive.

Next, the positional relationship among the first lens 2, the second lens 3, the lens frame 14, and the collar 15 in the lens unit 11 will be described with reference to FIG.
The first lens 2 and the second lens 3 are overlapped in the same manner as in the first embodiment. The lens pair consisting of the first lens 2 and the second lens 3 is inserted into the lens holding surface 14 b, and the first flange surface 2 d on one end side is in contact with each protrusion 14 d of the lens frame 14. It is touched.
The lens frame 14 is pushed into the tapered surface 15b of the collar 5 to be deformed to be in an assembled state so that the tapered surface 14a follows the tapered surface 15b and the lens holding surface 14b follows the lens side surfaces 2f and 3f. The first lens 2 and the second lens 3 are fitted between the collar 15 and the position in the axial direction is fixed by the adhesive portion 16b.
The first lens 2 and the second lens 3 are pressed against the protrusion 14d side so that the inter-surface distance is a preset inter-surface distance, and the second lens 3 is pressed against the lens frame 14 by the adhesive portion 16b. By fixing, the position in the axial direction is fixed.

The taper surface 14a of the lens frame 14 is in contact with the taper surface 15b of the collar 15 without rattling in the radial direction. In the present embodiment, the taper surface 14a and the taper surface 15b are in close contact with each other, so that they are not rattling.
In addition, the lens holding surface 14b of the lens frame 14 is in contact with the lens side surfaces 2f and 3f without rattling in the radial direction. In the present embodiment, the lens holding surface 14b is in close contact with the lens side surfaces 2f and 3f so that the lens holding surface 14b does not rattle.
Due to such a positional relationship, the optical axes O ₂ and O _{3 of} the first lens 2 and the second lens 3 and the central axis S of the lens frame 14 are within the range of the eccentric error caused by the respective component processing errors, The collar 15 is aligned with the central axis R of the collar 15.

With such a configuration, the collar 15 constitutes an outer holding member provided with a tapered surface 15b which is a tapered hole portion having a constant taper angle θ.
The lens frame 14 has a tapered surface portion 14a that is a tapered surface portion having a taper angle θ on the outer peripheral side, and a cylindrical surface portion that holds the lens side surfaces 2f and 3f of the first lens 2 and the second lens 3 on the inner peripheral side. Inner holding members each having a lens holding surface 14b are configured.
The assembly of the collar 15 and the lens frame 14 constitutes a lens holding frame 17 that holds the lens inside.
In the present embodiment, the first lens 2 that is the lens pair constituting the lens and the first flange surface 2d that is one end of the second lens 3 are received by the lens receiving portion 14c provided on the lens frame 14. ing.

Next, a method for assembling the lens unit 11 will be described.
The lens unit 11 is substantially the same as the first embodiment except that the lens frame 4 and the collar 5 in the first embodiment are replaced with the collar 15 and the lens frame 14. It can assemble by performing a fitting process and a position fixing process.
Hereinafter, a description will be given centering on differences from the first embodiment.

In the lens placement step of the present embodiment, the first lens 2 is placed on the projection 14d of the lens frame 14, and the first flange surface 3d of the second lens 3 is overlaid on each projection 2g of the first lens 2. Are different. The position of the first lens 2 and the second lens 3 in the direction orthogonal to the optical axis is not particularly limited as long as it is within the lens holding surface 14b.
The insertion process of the present embodiment is different in that the lens frame 14 in which the first lens 2 and the second lens 3 are inserted is inserted into the tapered surface 15b of the collar 15 from the tip of the lens frame 14.
As a result, the fitting portion 14m of the lens frame 14 is positioned between the lens side surfaces 2f and 3f disposed in the lens holding surface 14b and the tapered surface 15b of the collar 15, and the tapered surface 14b is formed on the tapered surface 15b. In the fitting process of this embodiment, the lens frame 14 is pushed in from the rear end side, the tapered surface 14a follows the tapered surface 15b, and the lens side surfaces 2f and 3f hold the lens. The difference is that the lens frame 14 is fitted into the collar 15 so that the surface 14b follows.
At this time, in the present embodiment, although one end side of the lens pair is received by the lens receiving portion 14c, the second flange surface 3e which is the other end side of the lens pair may move in the axial direction. While the lens frame 14 is pushed in, the second flange surface 3e or each projection 3g is pressed toward the distal end side of the lens frame 14 using an appropriate pressing jig. Thereby, while pushing in the lens frame 14, the protrusion 14d and the first flange surface 2d, and the protrusion 2g and the first flange surface 3d can be kept in contact with each other in the axial direction.
In the position fixing process of the present embodiment, the adhesive portions 16a and 16b are formed, and the point that the adhesive is applied to each position and cured in a state where the second lens 3 is pressed by the pressing jig is different.
This completes the assembly of the lens unit 11 as shown in FIG.

  According to the lens unit 11 and the method of assembling the lens unit 11 of the present embodiment, the lens frame 14 holding the lens side surfaces 2f and 3f with the lens holding surface 14b is pushed into the tapered surface 15b of the collar 15 and fitted into the lens holding unit. A frame 17 is formed. For this reason, the lens frame 14 is reduced in diameter in the process of fitting, and the lens side surfaces 2 f and 3 f and the lens holding surface 14 b are substantially in close contact with each other, and the first lens 2 and the second lens 3 are aligned with the collar 15. Can be assembled into a finished state. As a result, the decentering of the first lens 2 and the second lens 3 due to the assembly error with respect to the lens holding frame 17 can be removed and the assembly can be easily performed.

[Fourth Modification]
Next, a lens unit of a modified example (fourth modified example) of the present embodiment will be described.
FIG. 13 is a schematic cross section showing a modification (fourth modification) of the lens unit according to the second embodiment of the present invention.

As shown in FIG. 13, the lens unit 11 of the present modification includes a second lens 34 (lens), a lens frame 24 (an inner holding member) instead of the second lens 3 and the lens frame 14 of the second embodiment. ). The lens frame 24 and the collar 15 constitute a lens holding frame 27.
Hereinafter, a description will be given centering on differences from the first embodiment.

The second lens 34 is obtained by increasing the outer diameter of the lens side surface 3f of the second lens 3 of the first embodiment with respect to the first lens 2, and has a diameter D instead of the lens side surface 3f. ₃₄ (provided that the lens side surface 34f is a cylindrical surface of D ₃₄ > D ₂ ).

The lens frame 24 includes a first lens holding surface 24A (cylindrical surface portion) and a second lens holding surface 24B (cylindrical surface portion) instead of the lens holding surface 14b of the lens frame 14. In the lens frame 24, a wall-like portion sandwiched in the radial direction by the tapered surface 14a, the first lens holding surface 25A and the second lens holding surface 25B constitutes a fitting portion 24m.
The first lens holding surface 24A differs from the lens holding surface 14b only in that the length of the lens holding surface 14b in the axial direction is shortened to a length that covers the lens side surface 2f of the first lens 2 in the assembled state. Different. Accordingly, the inner diameter of the first lens holding surface 24A in the natural state is similar to the inner diameter _{D 14b} of the lens holding surface 14b.
The second lens holding surface 24B is formed on the inner periphery of the lens frame 24 between the end on the rear end surface 14e side of the first lens holding surface 24A and the rear end surface 14e. It is a cylindrical surface concentric with the first lens holding surface 24A provided in a range covering the lens side surface 34f.
The inner diameter of the second lens holding surface 24B is set to a size obtained by adding the difference between the outer diameter of the first lens 2 and the outer diameter of the second lens 33 to the natural inner diameter D _14b of the first lens holding surface 24A. Has been.

The lens unit 21 having such a configuration is similar to the second embodiment, except that the second lens 3 and the lens frame 14 of the second embodiment are replaced with the second lens 34 and the lens frame 24. Can be assembled.
However, in the lens arrangement step of this modification, when the first lens 2 and the second lens 34 are arranged in an overlapped state, the first lens 2 is arranged in the first lens holding surface 24A, and the second lens 34 is Two lenses are disposed in the holding surface 24B.
For this reason, in the insertion step and the fitting step, the first lens holding surface 24A and the second lens holding surface 24B are reduced in diameter as the lens frame 24 is reduced in diameter following the tapered surface 15b. It is fitted in a state following the side surface 2f and the lens side surface 33f.
As described above, this modification is an example in which the lens unit assembling method of the second embodiment can be applied even when the outer diameters are different from each other.
Such a lens unit 21 has the same effect as the lens unit 21.

In the above description of each embodiment and each modification, as an example, the description has been given of an example in which the lens group includes a pair of lenses that are in contact with each other in the optical axis direction. The lens specifications such as lens surface configuration, refractive power, and positive / negative refractive power are not particularly limited. In addition, the lens may have a single lens configuration or three or more lenses.
Further, in the case of three or more lenses, a lens pair in which lenses adjacent in the optical axis direction are in contact with each other may be configured, or may be spaced apart via a spacing ring, for example.
In addition, a plurality of lens pairs in contact with each other may be positioned apart from each other through, for example, a spacing ring.

In the description of each of the embodiments and the modifications described above, the example in which the lens is manufactured by synthetic resin molding has been described. However, the lens may be manufactured by glass molding or by glass polishing. Good.
For example, when manufacturing by glass polishing or a glass mold, the flange part, the projection part provided in the flange part, etc. can be abbreviate | omitted suitably. In this case, the positioning in the optical axis direction can use a curved surface or a plane outside the effective lens area.

In the description of each of the embodiments and the modifications described above, the inner holding member has been described as an example in which the cylindrical surface portion of the inner holding member follows the lens side surface by reducing the diameter in the fitting process. When the member is provided so that the diameter can be increased, a configuration in which the cylindrical surface portion in a natural state is formed to have a smaller diameter than the outer diameter of the lens.
In this case, the lens is pushed into the cylindrical surface portion and is assembled so that the cylindrical surface portion follows the lens side surface, the inner cylindrical surface portion and the tapered surface portion are expanded, and then the inner holding member is moved to the outer holding member. It is possible to fit into the tapered hole.

In the description of each embodiment and each modification described above, the cylindrical surface portion, the tapered surface portion, and the tapered hole portion have been described as having smooth surfaces such as a cylindrical surface and a conical surface, respectively. When the holding position of the lens by the cylindrical surface portion can be aligned with the central axis of the outer holding member with the diameter, it may not have a smooth surface.
For example, the cylindrical surface portion may be provided with a convex portion that contacts a part of the lens side surface, or may be provided with a concave portion that does not contact the lens side surface.
Moreover, the taper surface part and the taper hole part may protrude from the conical surface and can be easily deformed, or a concave groove may be formed on the surface of the conical surface.
Further, the cylindrical surface portion, the tapered surface portion, and the tapered hole portion may be formed of a rough surface.

In the second modified example, the inner holding member is a cylindrical member that does not have a cut, and has been described as an example in which the inner holding member is fitted by being elastically deformed or plastically deformed as a whole. Even if it is a shape-like member, the structure by which a part is elastically deformed or plastically deformed and diameter-reduced is also possible by setting it as the structure from which rigidity and intensity | strength differ in the circumferential direction.
For example, the slit 5h of the collar 5 of the first embodiment is filled with an elastic member having rigidity lower than that of the collar 5 to form an elastic deformation portion, and this elastic deformation portion is compressed and deformed in the circumferential direction. By doing so, the diameter can be reduced.

  Moreover, in the said 2nd Embodiment, although the example in the case of fixing the 2nd lens 3 and the lens frame 14 with the adhesion part 16a was demonstrated, in the state which pressed the 2nd lens 3 from the 2nd flange surface 3e side. A fixing member that engages with the lens frame 14 or is bonded and fixed may be provided.

In addition, the components described in the above embodiments and modifications can be implemented by appropriately combining or deleting them within the scope of the technical idea of the present invention.
For example, the male screw part 4e of the lens frame 4 of the first embodiment may be deleted to form a cylindrical surface.
Further, for example, a configuration in which the elastic deformation portion 45a of the first modified example is added to the lens frame 14 of the second embodiment may be adopted. Further, the lens frame 14 may be replaced with a cylindrical member capable of reducing the diameter as in the second modified example.

1, 11, 21, 31 Lens unit 2 First lens (lens)
2d, 3d 1st flange surface 2e, 3e 2nd flange surface 2f, 3f, 33f, 34f Lens side surface 2g, 3g Protrusion part 3, 33, 34 2nd lens (lens)
4 Mirror frame (outside holding member)
4b, 15b Tapered surface (taper hole)
4c Lens receiving part 4d, 14d Projection part 5, 35, 45, 55 Color (inner holding member)
5a, 14a, 55a Tapered surface (tapered surface)
5b, 14b, 55b Lens holding surface (cylindrical surface portion)
5h, 14h Slit (cut)
5i, 55i Lens receiving surfaces 6, 16a, 16b Adhesive portions 7, 17, 27 Lens holding frames 14, 24 Mirror frame (inner holding member)
14d Protrusion 15 Collar (outside holding member)
24A, 35A First lens holding surface (cylindrical surface portion)
24B, 35B Second lens holding surface (cylindrical surface portion)
45a Elastic deformation parts O ₂ and O ₃ Optical axes P, Q, R, S Center axis

Claims (6)

A lens,
A lens holding frame for holding the lens inside,
The lens holding frame is
An outer holding member provided with a tapered hole portion having a constant taper angle;
An inner holding member having a taper surface portion having a taper angle equal to the taper angle on the outer peripheral side and a cylindrical surface portion holding the lens side surface of the lens on the inner peripheral side;
With
The outer holding member or the inner holding member is provided with a lens receiving portion that receives one end side of the lens in the optical axis direction,
The tapered surface portion follows the tapered hole portion and the cylindrical surface portion follows the lens side surface between the lens side surface of the lens received by the lens receiving portion on one end side in the optical axis direction and the outer holding member. The lens unit, wherein the inner holding member is fitted into the lens unit. The inner holding member is
Having a cut that penetrates between both axial ends,
The lens unit according to claim 1, wherein an inner peripheral length of the cylindrical surface portion is equal to or less than an outer peripheral length of the lens. The lens is
The lens unit according to claim 1 or 2, comprising a lens group including at least one pair of lenses that are in contact with each other in the optical axis direction. The lens is
Including multiple lenses with different outer diameters,
The cylindrical surface portion is
The lens unit according to any one of claims 1 to 3, wherein a plurality of lenses are provided corresponding to the outer diameters of the plurality of lenses. A method of assembling a lens unit for holding a lens inside a lens holding frame,
The lens holding frame holds an outer holding member having a tapered hole portion having a constant taper angle, a taper surface portion having a taper angle equal to the taper angle on the outer peripheral side, and a lens side surface of the lens on the inner peripheral side. An inner holding member each having a cylindrical surface portion, and the outer holding member or the inner holding member is provided with a lens receiving portion that receives one end side of the lens in the optical axis direction,
Assembling method of the lens unit,
A lens placement step of placing one end side of the lens in the optical axis direction on the lens receiving portion;
The tapered surface portion is arranged along the tapered hole portion of the outer holding member such that the inner holding member is positioned between a lens side surface of the lens disposed in the lens receiving portion and the outer holding member. An insertion step of inserting the inner holding member;
A step of fitting the inner holding member into the outer holding member so that the inner holding member is pushed, and the tapered surface portion follows the tapered hole portion and the cylindrical surface portion follows the lens side surface;
A position fixing step for fixing a relative positional relationship between the inner holding member, the outer holding member, and the lens after the fitting step;
A method of assembling a lens unit, comprising: The inner holding member has a cut that penetrates between both axial ends.
In the insertion step,
The cut is spaced apart in the circumferential direction so that the inner diameter of the cylindrical surface portion of the inner holding member is larger than the outer diameter of the lens,
In the fitting step,
When the inner holding member is pushed in, the tapered surface portion follows the tapered hole portion, thereby reducing a circumferential interval of the cut, and the cylindrical surface portion follows the lens side surface. The method for assembling the lens unit according to claim 5.

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