JPH04166904A - Lens holding barrel - Google Patents

Abstract

PURPOSE:To eliminate decentering or inclination of a lens, to increase mounting accuracy and to facilitate assembly by holding the lens with projection parts in which the center of the inscribed circle conforms with the optical axis and a receiver whose holding surface crosses the optical axis of the lens. CONSTITUTION:A holding barrel 1 has a cylinder part 2 with the center axis conforming with the optical axis of a lens at its almost center. Projections 3 formed at the positions where the circumference of the cylinder part 2 is divided into three parts are brought into contact with the outer circumferential surface of the lens inserted into the cylinder part 2 and are plane projections in the chord state. As so formed that the center of the inscribed circle of these projections 3 is positioned on the optical axis of the lens, even though the center of the cylinder part 2 is decentered from the optical axis of the lens, the lens is not decentered. Also, a butt part 2 formed in the ring state on the inner surface of the cylinder part 2 positions the lens in the optical axis direction. Receivers 5 as receiving surfaces of the lens in the optical axis direction are formed at the positions where the circumference of this butt part 4 is divided into three parts. A holding surface of a top part 5a of the receiver 5 crosses the optical axis of the lens.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lens holding lens barrel that can hold a lens in alignment with the optical axis of the lens.

[Prior Art] In recent years, plastic molded products are increasingly being used for lens holding barrels. FIG. 17 shows a conventional lens holding lens barrel 100 molded by Plus Deck, which has a cylindrical portion 101 into which a lens L is inserted, and an abutment portion 102 formed inside the cylindrical portion 101. .

The cylindrical portion 101 contacts the outer circumferential surface of the lens L to position the lens L in the radial direction, and the abutting portion 102 positions the lens L in the optical axis direction by contacting the lens L inserted into the cylindrical portion 101. This is what we do. The lens L inserted into the cylindrical portion 101 is held within the lens holding barrel 100 by means such as adhesion or caulking.

The molding die for molding such a lens holding barrel 100 is assembled by inserting a mold into a mother mold.While the mold molds the outer part of the lens holding lens barrel 1.00, The inner part of the lens holding barrel lOO is molded. The inner surface of the cylindrical portion 101 and the abutting portion 102 are molded by nesting. When molding with this mold, the shape of the mold parts must be adjusted to prevent deformation of the lens holding barrel, that is, to prevent eccentricity or tilting of the lens when mounted.
When molding, it is necessary to pay close attention to the wall thickness, the position of the resin injection gate, etc.

[Problems to be Solved by the Invention] However, even if the utmost care is taken during molding, and even if the precision of the molding die such as the insert is increased, deformation of the molded lens holding lens barrel cannot be completely eliminated. When a lens that requires high centering accuracy is mounted on such a lens barrel, the mounting accuracy deteriorates due to the deformation. This specific factor was based on the following two items.

- Eccentricity of the lens The inner surface of the cylindrical portion 101 (lens fitting portion) into which the outer peripheral surface of the lens L fits is deformed, and the center of the inscribed circle of the lens fitting portion is deviated from the optical axis of the lens L. . This causes an eccentricity of a distance of 1tliδ as shown in FIG. 17 fal.

(2) Inclination of the Lens Since the surface of the abutting portion 102 in the optical axis direction is deformed and is not perpendicular to the optical axis of the lens, the angle ε1 shown in FIG. 17(b). The lens is in a tilted state as shown by ε2.

In order to deal with these two factors, conventionally, the diameter of the lens fitting part, that is, the outer diameter of the insert, was set large in consideration of the eccentricity of the lens fitting part, and the diameter of the lens fitting part was set large, and the outer diameter of the insert was set large. The receiver of this part required complicated assembly such as adjusting the state of contact with the surface, and required skill.

The present invention has been made in view of these problems, and it is an object of the present invention to provide a lens holding lens barrel that has high mounting accuracy without eccentricity or inclination of the lens, and is easy to assemble.

1. Means for Solving Problem 1] -2 In order to achieve the object, the inventor conducted intensive research and found that the direction of deformation of the molded product in the insert of the same diameter forming the inner surface of the cylindrical part of the lens holding barrel. We discovered that the amount of deformation is constant, and based on this, we modified the insert to correct the deformation of the molded product that occurs with inserts of the same diameter.
The present invention has been made in that it is possible to mold a lens holding lens barrel that does not cause eccentricity or inclination of the lens by molding while maintaining constant molding conditions when correcting the insert.

That is, the lens holding lens barrel of the present invention formed in this manner has a cylindrical portion for positioning the lens in the radial direction and an abutment portion for positioning the lens in the optical axis direction, and (1) the cylindrical portion. (1) Protrusions whose inscribed circle has the same diameter as the lens outer diameter and whose center coincides with the optical axis of the lens are provided at at least approximately three equal parts of the abutting portion; A receiver seat is provided at equal positions, the envelope surface of the top of which is perpendicular to the optical axis of the lens; (2) The lens is held in position by each projection of the cylindrical portion and each top of the abutting portion. It is characterized by:

[Effect 1] In the above configuration, the cylindrical portion of the lens holding barrel is aligned with the optical axis of the lens, and the surface of the lens holder is perpendicular to the optical axis of the lens, so the mounting accuracy of the assembled and held lens is extremely high. It will be expensive.

[Example] Hereinafter, the present invention will be specifically explained by referring to an illustrative example. In addition, in each embodiment, the same elements are given the same reference numerals and corresponded to each other, thereby omitting redundant explanation.

(First Embodiment) FIGS. 1 to 5 show a first embodiment of the present invention, and FIGS. 1 and 2 are a front view of the lens holding barrel 1 and its II.
-II line sectional view.

The lens holding barrel 1 has a cylindrical portion 2 approximately centered on an axis that coincides with the optical axis of the lens. A lens is inserted into the cylindrical portion 2 through its open end, and its inner diameter is formed to be somewhat larger (for example, about 0.5 mm larger in diameter) than the outer diameter of the lens. Protrusions 3 are formed at three equal positions on the circumference of the cylindrical portion 2. The protrusion 3 contacts the outer circumferential surface of the lens inserted into the cylindrical portion 2 at three equal parts (see Fig. 4(a)), and in this embodiment, it is an arcuate planar protrusion. ing. The protrusion 3 is dimensioned so that its inscribed circle has the same diameter as the outer diameter of the lens, and is shaped so that the center of the inscribed circle is located on the optical axis of the lens. In this case, the protrusion 3 may be formed under the above conditions, and even if the center of the cylindrical portion 2 is eccentric from the optical axis of the lens, the lens will not become eccentric.

Further, a ring-shaped abutting portion 4 is formed on the inner surface of the cylindrical portion 2. The abutting portion 4 is for positioning the lens in the optical axis direction, and a seat 5 is formed at three equal positions on the circumference of the abutting portion 4 to serve as a receiving surface for the lens in the optical axis direction. has been done. The seat 5 is formed such that the envelope surface of its top portion 5a is perpendicular to the optical axis of the lens. There are 43 people in this example,
Each seat 5 is formed at a position corresponding to the arc-shaped protrusion 3 of the cylindrical portion 2.

FIG. 3 shows an insert 10 for molding such a lens holding barrel 1. As shown in FIG. The insert 10 has a cylindrical large-diameter portion 11 that forms the inner surface of the cylindrical portion 2 of the lens holding barrel, and a small-diameter portion 12 that forms the inner surface of the abutment portion 4.

A flat portion 13 for forming the arc-shaped protrusion 3 of the lens holding barrel 1 is formed at three equal parts of the large diameter portion 11 . Further, a groove portion 14 for forming the seat 5 is formed at the end of the flat portion 3 on the small diameter portion 12 side.

Next, the procedure for creating this nest 10 will be explained.

First, a mark such as a mark is attached to a specified position of the insert 10 with respect to a matrix (not shown) for molding the outer peripheral surface of the tube portion 2 of the lens holding barrel 1, so that the combined position of the matrix and the insert is always constant. Make it so that At this time, the entire diameter of the large diameter portion 11 and small diameter portion 12 of the insert 10 is cylindrical, and the flat portion 13 and groove portion 14 are not formed.

Next, plane polishing is applied to the three equal parts of the large diameter part 1. At the initial stage of this surface polishing, the inscribed circle is made larger than the outer diameter of the lens, and each time the molding is repeated,
Find out the direction of deformation from molded products. Then, the amount of polishing of each plane is gradually changed according to the amount of deformation, and the plane portion 13 is corrected so that its inscribed circle has the same diameter as the outer diameter of the lens. Such correction can be easily carried out because the insert 10 is plane-polished from the outside and is simply polished in a direction that corrects the deformation caused by molding.

After forming the flat portion 13 in this manner, a groove portion 14 is formed at the end of the flat portion 13 on the small diameter portion 12 side. When forming this groove portion 14, the mold is gradually corrected by repeating trials, and finally the envelope surface of the top of the seat 5 is perpendicular to the optical axis of the lens. This mold modification can also be easily carried out because the amount of modification can be determined by finding the direction of deformation of the seat 5. Then, by using the insert 10 modified as described above and performing molding based on the molding conditions at the time of modification, the lens holding barrel 1 described above can be molded.

FIG. 4 shows a state in which the lens L is mounted on the lens holding barrel 1 formed in this manner. In the illustrated example, a meniscus lens is used as the lens L, and when this lens L is inserted into the cylindrical part 2, the outer peripheral part fits into the arcuate protrusion 3 at three places, and the flat part of the lens L It comes into contact with the catch 5 and is positioned and held within the cylindrical part 2 by the protrusion 3 and the catch 5. In this holding state, the center of the inscribed circle of the protrusion 3 is located on the optical axis of the lens L, so the lens L does not become eccentric, and the envelope surface of the top of the catch 5 is aligned with the lens L. Since it is perpendicular to the optical axis, the lens L will not be tilted. ゛In this holding state, since the protrusion 3 has an arc shape, the lens L and the protrusion will become closer as the protrusion 3 moves away from the contact area. In Figure 4 (al), the adhesive 6 is injected from both sides of the lens contacting part of the protrusion 3.The adhesive 6 has a low viscosity of about 200 poise. By using the silicone-based adhesive 1, it penetrates the contact surface of the lens L by capillary action at the same time as the adhesive, and also flows in the optical axis direction to reach the abutment part 4.Moreover, this adhesive Having elasticity after curing, the lens L can secure an adhesion area with its optical axis aligned with the axis of the lens holding barrel 1, and the lens L is firmly held without movement.

If the lens L is a glass lens, dimensional changes due to temperature changes are small, but deformation due to dimensional changes of the lens holding barrel, which is a plastic molded product, is large, and this deformation occurs at the three arc-shaped protrusions. However, since the adhesive 6 follows and deforms around the protrusion 3, the adhesive strength does not decrease and the optical axis of the lens does not shift. Therefore, it is possible to respond favorably to temperature changes.

Further, in the above embodiment, the outer diameter of the lens L and the diameter of the inscribed circle of the protrusion 3 are the same size, but the outer diameter of the lens is about 0.03 mm larger than the inscribed circle. However, since the lens holding lens barrel 1 is a plastic molded product, the diameter expands and deforms when the lens L is inserted, so no dimensional problems occur.

On the other hand, even when the outer diameter of the lens is as small as about 0.02 mm, the optical axis of the lens and the axis of the lens holding barrel coincide with each other due to the penetration of the adhesive 6. Furthermore, the projections 3 and seats 5 may be formed at three or more equal positions to hold the lens.

5 to 7 show modified examples of the bonding mode using the adhesive 6. FIG.

In the example shown in FIG. 5, the adhesive 6 is applied around the entire circumference of the lens L, thereby making it possible to provide a waterproof function while maintaining the mounting accuracy of the lens. In the example shown in FIG. 6, an adhesive 6 is applied between the inner circumferential surface of the cylindrical portion 2 and the outer circumferential surface of the lens L, and in this case, the adhesive 6 can be easily injected.

In the example shown in FIG. 7, an adhesive 6 is applied between the lens L and the seat 5.
This is convenient for preventing the adhesive 6 from flowing.

FIG. 8 shows an example in which a tapered guide surface 7 is formed at the opening of the cylindrical portion 2 into which the lens L is inserted. This facilitates the insertion of the lens. Further, FIG. 9 shows an example in which the opening end of the cylindrical portion 2 into which the lens L is inserted is heat caulked to form the caulked portion 8, and in this case, no adhesive is required.

Fig. 10 shows an actual example of the lens L, and there are cases where the lens L is thin as shown in the figure (al), or whose outer peripheral shape is misaligned with the optical axis as shown in the figure (bl, (cl). The advantage is that it can be maintained with high mounting accuracy even when
・There is.

(Second example) 11 and 12 show a second embodiment of the invention.

In this second embodiment, a convex portion 3 within the cylindrical portion 2 is formed into an arc shape. By doing so, the top of the catch seat 5 becomes even clearer, which has the advantage of making it easier to manage the dimensions of the inscribed circle.

Note that the protrusion 3 is not limited to an arcuate shape, but may also be triangular in shape as shown in FIG. 13 to obtain the same effect.

(Third Embodiment) FIGS. 14 and 15 show a third embodiment of the present invention,
The molding positions of the arc-shaped projection 3 of the cylindrical portion 2 and the seat 5 of the abutment portion 4 are different. Further, the catch seat 5 has a semicircular arc shape.

In this embodiment, since the three apexes of the seat 5 are clearly defined, the dimensions of the envelope surface and the optical axis of the lens can be easily controlled. FIG. 16 shows a modification of the catch 5, which has a trapezoidal shape. In this case as well, dimensional control becomes easier, but in addition, the area that comes into contact with the lens is wider, so
Mounting accuracy becomes even higher. Note that the shape of the seat 5 of the third embodiment can also be applied to the first and second embodiments.

[Effects of the Invention] As explained above, the present invention holds a lens using a protrusion whose inscribed circle center coincides with the optical axis of the lens and a seat whose envelope surface is perpendicular to the optical axis of the lens. , the lens can be positioned without eccentricity or tilting, and the mounting accuracy is increased.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 show the first part of the lens holding barrel of the present invention.
A front view and a sectional view taken along the line II-II of the embodiment,
FIG. 3 is a perspective view of the insert used for molding the lens holding barrel, FIG. ) is a front view and a sectional view showing the deformation of the adhesive, FIGS. 6 and 7 are a front view and a sectional view respectively showing the deformation of the adhesive, and FIGS. 8 and 9 are , sectional views showing modified examples of the cylindrical portion, FIGS. 10 (al to c) are side views showing modified examples of the lens, and FIG.
1 and 12 are a front view and a partial perspective view showing a second embodiment of the present invention, FIG. 13 is a partial perspective view showing a modification thereof, and FIGS. 14 and 15 are a front view and a partial perspective view showing a second embodiment of the present invention. A front view and a partial perspective view showing the third embodiment, FIG. 16 is a partial perspective view showing a modification thereof, and FIGS. 17(a) and (b)
These are a front view and a sectional view showing a conventional example. 1...Lens holding barrel 2...Cylinder part 3...Protrusion part 4...Abutting part 5...Socket L...Lens ■...Lens holding barrel 2... Cylindrical portion 3... Protrusion 4... Abutting portion 5... Receptacle 4 Figure (a') Figure 8 Figure 9 Figure 14 Figure 17 ('a) January 21, 1991 Day

Claims (1)

[Claims] (1) In a lens holding lens barrel having a cylindrical portion for positioning the lens in the radial direction, and an abutment portion provided within the cylindrical portion for positioning the lens in the optical axis direction, at least approximately three portions of the cylindrical portion Protrusions are provided at equally divided positions, the inscribed circle of which has the same diameter as the lens outer diameter, and the center of the inscribed circle coincides with the optical axis of the lens, and at least approximately three equal parts of the abutment part,
A lens holding lens barrel, characterized in that the lens is provided with a seat whose top envelope surface is orthogonal to the optical axis of the lens, and the lens is held in a positioned state by each projection of the cylindrical portion and each top of the abutting portion. .