JPH0534641B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plastic lens, and more particularly to a structure for fixing a plastic lens in a lens group including the plastic lens.

A photographing lens of a camera, an eyepiece of a viewfinder, etc. are constructed by combining two or more lenses, and each lens is arranged at a predetermined distance apart. Conventionally, each of these lenses
Glass lenses are often used, but recently plastic lenses have been adopted.

Conventionally, as shown in Fig. 1a, a lens group made up of three plastic lenses 1, 2, and 3 is used to form the eyepiece of a finder optical system using plastic lenses, for example. A convex lens 1 is arranged, a convex lens 3 is arranged on the right side, and a concave lens 2 is arranged between biconvex lenses 1 and 3, respectively. In order to fix the lenses 1, 2, and 3 adjacent to each other so as to maintain a predetermined distance from each other, on the outer periphery of both sides of the concave lens 2,
While the flat surface parts 2a and 2b perpendicular to the lens optical axis are provided, a short cylindrical part extending parallel to the optical axis is provided on the outer peripheral edge of the surface of the left convex lens 1 facing the concave lens 2. The separation distance holding part 1a is integrally formed, and the concave lens 2 of the right convex lens 3 is
A short cylindrical distance holding part 3a extending parallel to the optical axis is integrally formed on the outer peripheral edge of the side surface facing the .
The respective tip surfaces of the concave lens 2 are connected to the flat surface portion 2a of the concave lens 2,
2b, each lens 1, 2, 3
into the fixing cylinder 5. In this state, the outer peripheral surface of each lens 1, 2, and 3 is tightly fitted into the inner peripheral surface of the fixing tube 5, and the peripheral edge of the outer surface of the convex lens 1 is in contact with the lens holding portion 5a of the fixing tube 5. The peripheral edge of the outer surface of the convex lens 3 is in contact with the fixing cylinder 5.
By being pressed by the lens holding frame 6 screwed onto the lens, the optical axes of each lens are aligned, and
A predetermined separation distance is maintained.

In another known configuration, the lens group shown in FIG. 1b includes a glass lens 12 and a plastic lens 1.
It is a three-element finder lens that combines lenses 1 and 13, and the three lenses 11, 12, and 13 are
From the left in the figure, plastic convex lens 1
1. A concave lens 12 made of glass and a convex lens 13 made of plastic are arranged in this order, and are fixed with a fixing cylinder 15 and a lens holding frame 16.

In FIG. 1b, plastic lens 1
1 and 13, the outer peripheral edge portions thereof each extend parallel to the optical axis of the lens, and the tip surfaces 11b and 11b of the extension portions 11a and 13a respectively extend to the glass lens 12.
It is formed in exactly the same curved shape as the outer circumferential edges 12a, 12b of the curved surface of the glass lens 12, and completely matches the outer circumferential edges 12a, 12b which are part of the curved surface of the glass lens 12,
They are now in face-to-face contact with each other.

Furthermore, FIGS. 2a and 2b show a conventional example different from those shown in FIGS. 1a and 1b, and the conventional example shown in FIG. Plastic lens located at 17,1
9 is provided with protrusions 17d and 19d, respectively,
The end face 1 of the lens support part of the plastic lens 18 has these protrusions 17d and 19d arranged in the middle.
It is in contact with 8c and 18c.

Figure 2b also shows one plastic lens 1.
Only the plastic lens 9 is provided with a protrusion 19d, and this protrusion 19d is in contact with the end surface 18c of the lens support portion of another plastic lens 18 arranged adjacently.

Note that the other fixing cylinder 15 and presser frame 16 are
It has the same configuration as in Figure b, and 17b, 18b and 19b are the plastic lenses 17, 18, 19
This figure shows the lens support part of the figure.

Now, in the above conventional technology, when the lens is inserted into the lens frame, the distance between the lenses is determined by a flange-like ring integrally formed on the plastic lens or a rod-like foot formed in the thrust direction. This is a lens holding device that is more efficient than the drop-in method.

However, it has the following drawbacks.

Plastic lenses are molded using various methods, but the surface that fits into the lens frame (the outer peripheral surface of the lens) is prone to burrs and other irregularities due to gate processing. Moreover, it is very difficult to make the shape perfectly circular. Therefore, when the lenses are inserted and held in the lens frame, the relative positions between the lenses are determined by the fitting state with the lens frame, which causes optical axes to shift in the lens group. This optical axis misalignment of the lens group is a cause of significant deterioration in the performance of the lens system, and usually requires a deburring process and peripheral processing after molding for a single lens.

Furthermore, in the above-mentioned conventional technology, even if a mistake occurs during assembly of the lens group, such as inserting the lenses into the lens frame in the wrong order, or holding the lenses in the wrong order, the lens group is assembled as is. . If the wrong lens group is inserted, the performance will not only deteriorate, but the lens will not function as a lens at all. Therefore, post-assembly inspection is required,
The disadvantage was that defective products were often produced and workability was extremely poor.

Therefore, the present invention has been developed to eliminate the various drawbacks of the prior art.

Embodiments of the holding device of the present invention will be described in detail below with reference to the drawings.

First, FIGS. 3 to 5 show three plastic lenses A, B, and C to be held in the lens holding device of the present invention.

Thus, in the plastic lenses A, B, and C, the lens bodies 20, 40 made of convex lenses and the lens body 30 made of concave lenses are provided with outer peripheral portions 20a, 30a, and 40a, respectively, and each outer peripheral portion 20a, 30a, and 40a is provided with outer peripheral portions 20a, 30a, and 40a, respectively. Fan-shaped lens support pieces 21 and 3 whose center point is the optical axis of each lens body 20, 30, and 40 in the thrust direction.
By arranging a plurality of numbers 1, 32, and 41, they are integrally molded from an optical resin material.

Furthermore, the plastic lens A is placed adjacent to the left side of the plastic lens B, and the plastic lens C is placed adjacent to the plastic lens B.
The plastic lenses A, B, and C constitute a lens system adjacent to the right side of the plastic lenses A, B, and C.
The lens support pieces 21, 31, 32, and 41 are arranged in a mutual relationship corresponding to the order in which the plastic lenses A, B, and C are held.

That is, each lens support piece 21 of plastic lens A corresponds to each lens support piece 31 on the left side of plastic lens B, and each lens support piece 41 of plastic lens C corresponds to each lens support piece 32 on the right side of plastic lens B. The correspondence relationship with each lens support piece 21, 31, 32, 41 will be explained in detail with reference to FIGS. 3 to 5.

First, each lens support piece 21 of the plastic lens A consists of three lens support pieces 21a, 21b, 2
1c, and each lens support piece 21a,
21b, 21c are protrudingly provided with notches 22 spaced apart from each other at a constant interval α1 when viewed from the lens plane as shown in FIG.
1c consists of a fan-shaped piece with a fan-shaped angle β1 with the optical axis as the center point 0, and its both end surfaces 23 are connected to the other lens support piece 21.
Together with the end surface 23 of the lens support piece 31 on the left side of the plastic lens B, the inner dimension (α1 ) are formed to correspond to the outer dimensions (fan-shaped angle β2) of each lens support piece 31 on the left side of the plastic lens B, which will be described later.

Further, the diameter of the inner circumferential surface 25 of each lens support piece 21a, 21b, 21c of the plastic lens A is larger than the effective diameter of the lens system, and the length of each lens support piece 21a, 21b, 21c in the thrust direction is larger than the effective diameter of the lens system. The lens is formed to have a length necessary for a predetermined lens spacing required when configuring a lens system together with other plastic lenses B and C, and further,
The distal end surface of each lens support piece 21 forms a joint surface 24 with another lens B.

On the other hand, regarding Plastic Cleanse B, the fourth
As shown in figures a to d, each lens support piece 31 on the left side
are three lens support pieces 31a, 31b, 31c
is the fan-shaped angle β2 (the fourth
A notch 33 with an interval angle α2 is formed between each lens support piece 31a, 3b, 31c, and an outer dimension (β1 )
It is formed to correspond to

In addition, the other configurations, ie, the lengths of each lens support piece 31a, 31b, 31c, the configuration of the inner circumferential surface 34, and both end surfaces 35, are the same as those of the plastic lens A.
The lens supporting pieces 21 and notches 22 are formed to correspond to each other. 39 is each lens support piece 3
1 and 32, which are the joint surfaces with plastic lenses A and C.

Furthermore, each lens support piece 41 of the plastic lens C has four lens support pieces 41a, 41b, 4
1c and 41d, and protrudingly provided with notches 42 at a constant interval α3 when viewed from the lens plane,
And each lens support piece 41a, 41b, 41c,
41d consists of a sector-shaped piece having a sector angle β3 with the optical axis as the center point 0, and both end faces 43 of the sector-shaped piece fit into each lens support piece 32 on the right side of the plastic lens B, which will be described later, together with the end faces 43 of other lens support pieces 41. It will be a meeting.

In addition, the outer dimension of each lens support piece 41 (fan angle β3)
The inner dimension (α3) of the notch 42 between the lens supporting pieces 41 and the inner dimension (α4) of each notch 36 between the right lens supporting pieces 32 of the plastic lens B (described later)
and the outer dimensions (fan-shaped angle β4) of each lens support piece.

Therefore, each lens support piece 32 on the right side of the plastic lens B with respect to each lens support piece 41 of the plastic lens C has four lens support pieces 32a,
32b, 32c, and 32d, and each lens support piece 32a, 32b, 32c, and 32d is also made of a fan-shaped piece having a sector angle β4 with the optical axis as the center point 0, and is arranged with cutouts 36 at a constant interval α4. has been done.

In addition, other configurations, that is, each lens support piece 3
The lengths of lenses 2 and 41 are set to the length required between both lenses B and C, and the inner circumferential surfaces 37 and 44 are formed to have a larger diameter than the effective diameter of the lens system. 45
is a lens B consisting of the tip surface of each lens support piece 41
It is the joint surface with.

Reference numeral 38 indicates both end surfaces of each lens support piece 32 of the plastic lens B.

As is clear from the above description, regarding the plastic lenses A and C that are adjacent to and connected to both the left and right sides of the plastic lens B, the number of lens support pieces 21 and 31 on the former and left side is three, whereas By changing the number of lens support pieces 41 and 32 on the latter and the right side to four, each plastic lens A, B, and C can be accurately combined according to the combination required for the combination of the lens system at all times. It is configured so that it can be done.

That is, when assembling each of the plastic lenses A, B, and C having the above configuration, as shown in FIG. Each lens support piece 21 of A is attached to plastic lens B.
After aligning with each notch 33 between each lens support piece 31 on the left side (this alignment allows each lens support piece 31 to be aligned with the notch 22 conversely), 21 and 31 can be fitted to each other while fitting into the notches 33 and 22 between the gaps, and at the same time, the plastic lenses A can be attached at intervals corresponding to the length of each lens support piece 21 and 31. can be bonded to the left side of the plastic lens B.

In the same manner, by fitting the plastic lens C to the right side of the plastic lens B while fitting the lens support pieces 32 and 41 into the notches 36 and 42, the length of each lens support piece 32 and 41 is adjusted. They can be joined at corresponding intervals and three plastic lenses A, B, C can be joined together to form a predetermined lens group.

Figure 7 a and b are plastic lenses A, B, and C.
It is an explanatory diagram regarding the misalignment of the lens group consisting of the fitting surfaces 23, 35, 43, 38 between the lens support pieces 21, 31, 32, 41 between the cemented surfaces of the lenses A, B, and C. There must be a certain amount of clearance δ between the lenses, and due to this clearance δ, each lens A, B, and C is shifted in the radial direction, and the amount of shift is the amount of deviation of the optical axis of the lens group. δ′. In other words, the optical axis deviation δ' is the fitting surface 23 of the lens support piece 21, 31, 32, 41 of each lens A, B, C.
This is determined by the clearance δ between 35, 43, and 38.

Incidentally, in the above explanation, an example in which three plastic lenses A, B, and C are connected to each other has been described, but it is of course possible to form a lens group by connecting two or four or more lenses. The lens supporting piece protruding from the outer periphery of the plastic lens may be protruded from only one side, as in plastic lenses A and C, or on both left and right sides (both front and back), as in plastic lens B. may be set up and configured.

Moreover, it goes without saying that the shape, number, etc. of each lens support piece of each plastic lens can be modified as required.

Now, regarding the case of constructing a lens holding device using the plastic lens mentioned above,
To explain this with reference to FIG. 8, first, the lens frame 50 has an inner diameter corresponding to the outer diameter of the plastic lens A and an inner peripheral surface 5 into which the plastic lenses B and C can be inserted.
1, and one open end 51a of the inner peripheral surface 51 has plastic lenses A, B,
The effective diameter of the lens group consisting of C is ensured at its inner diameter, and an abutting surface 52 that abuts the outer peripheral part 20a of the plastic lens A is provided protrudingly, and a presser ring 53 is screwed onto the outer periphery of the other open end 51b. Threaded part 5
4 is screwed on.

Therefore, the plastic lens A is inserted into this lens frame 50 and stored while the outer peripheral part 20a of the lens body 20 is butted against the abutting surface 52, so that the outer peripheral part 20a of the lens A is brought into contact with the inner peripheral surface 51 of the lens frame 50. Centering is achieved by fitting.

Next, attach the plastic lenses B and C to the lens frame 5.
0, and insert the lens support pieces 3 of each lens B and C into
1 and 42 are fitted with the lens support pieces 21 and 32 and dropped into the
can be connected to lens A and stored while centering. In this case, as shown in Figure 8,
The outer periphery of plastic lenses B and C is the lens frame 5.
A clearance is formed between the inner circumferential surface 51 of 0 and
It can be shifted in the radial direction.
That is, the outer circumferential portion of one lens fits into the inner circumferential surface of the lens frame, and the other lenses have smaller outer diameters than the fitting lenses so that they can be shifted in the radial direction.

Thereafter, by screwing an annular retaining ring 53 with an opening 55 having an effective lens diameter on the inner diameter to the threaded portion 54 of the lens frame 50, the plastic lenses A, B, and C can be attached to the lens abutment surface 52 within the lens frame 50. It is held fixed while being pressed in the thrust direction.

However, if the plastic lenses A, B, and C are housed in the wrong order of combination with respect to the lens frame 50, each of the lens support pieces 2 protruding from each other will be damaged.
1, 31, 32, and 41 cannot be fitted into each other, and the distances between the plastic lenses A, B, and C are different from the distance required for a given lens group, as shown in FIG. , the lens B assembled in the rear part protrudes from the frontage 51b of the lens frame 50, and cannot be held by the presser ring 53.

Figures 10 to 12 show a second embodiment of the present invention, and this embodiment uses three plastic lenses A, B, and C, similar to the first embodiment shown in Figures 3 to 5. In particular, when the lenses A, B, and C are bonded together, the number of lens support pieces 21, 31, 32, and 41 is all four, and the fan angle (β) is In other words, the fan angle (β1) of the lens support piece 21 is maximized, and then the fan angle (β2) of the lens support piece 32 is decreased (β1).
>β2), and in response to this, the lens support piece 3
1,41 was formed.

The other configurations are the same as those in the first embodiment, so the same numbers are given to each part and the explanation thereof will be omitted.

Further, the structure of the lens holding device can be constructed in the same manner as shown in FIG. 8, and detailed illustration and explanation thereof will be omitted.

Generally, plastic lenses are made by putting resin into a mold cavity under high pressure and high temperature to solidify and form a lens, so there is a resin entrance (gate) on the outer periphery.
or burrs remain. In the conventional structure, the relative position of the lens group is determined by the fit between the outer peripheral surface of the lens and the frame, so variations in gates and burrs can cause misalignment of the optical axis, which greatly reduces lens performance. A deburring process and peripheral machining were required.

In the present invention, the lens support piece provided integrally with the plastic lens and the notch part fit together, and the optical axis shift of the lens group is determined by the clearance between the lenses. A lens group can be assembled very easily while maintaining the performance of a predetermined lens system without secondary processing of individual items.

With conventional lens holding devices, when inserting and holding a lens in a frame, there are many defects such as incorrectly inserting the lens during assembly, and it is necessary to inspect each lens in the assembly process, but in the present invention, By changing the lens support piece and notch formed on the plastic lens between adjacent lenses, it is possible to prevent incorrect insertion of lenses, maintain the performance of a given lens group, and eliminate defects during assembly. , a lens holding device consisting of a plurality of lens groups can be assembled very accurately and easily.

[Brief explanation of drawings]

1a, b and 2 a, b are longitudinal sectional side views and partially omitted longitudinal sectional views showing a conventionally known lens holding device, and FIGS. 3 to 5 show a first embodiment of the present invention. Plastic lenses are shown for explanation, and FIGS. 3a, 4a, and 5a are perspective views of each lens, and FIGS. 3b, 4b, and 5b are longitudinal cross-sectional views of the lenses, 3c, 4c, d, and 5c are the same plan views, FIG. 6 is a perspective view showing the combined state, and FIGS. 7a and b are plan views showing the misalignment of each lens. FIG. 8 is a longitudinal cross-sectional side view of the lens holding device of the present invention;
The figure is a vertical sectional side view showing a state in which the order of assembly of each lens into the lens frame is incorrect, Figures 10 to 12 show plastic lenses for explaining the second embodiment of the present invention, and Figures 10a and 11 Figure a, 1st
Figure 2a is a vertical sectional view of each lens, Figure 10b is the first
Figures 1b and 1c and Figure 12b are the same plan views. A, B, C...Plastic cleanse, 20,3
0, 40...Lens body, 20a, 30a, 40
a...Outer peripheral part, 21, 31, 32, 41... Lens support piece, 22, 33, 36, 42... Notch part,
23, 35, 38, 43...both end surfaces (fitting surfaces),
24, 39, 45...Joint surface, 50...Mirror frame, 5
DESCRIPTION OF SYMBOLS 1... Inner peripheral surface, 52... Abutment surface, 53... Presser ring, 54... Threaded part, 55... Opening.

Claims (1)

[Claims] 1. In a lens holding device for storing and fixing a plurality of plastic lenses in a lens frame at predetermined lens intervals, an outer periphery is formed in the shape of a flange on the outer periphery of the lens body of each adjacent plastic lens, and the outer periphery of each adjacent plastic lens is formed on the outer periphery of the lens body. A plurality of fan-shaped pieces having a fan-shaped cross section centered on the optical axis are provided in the section with cutouts at regular intervals and protrude toward each of the adjacent outer peripheries, and the fan-shaped pieces of the adjacent outer periphery The notches are fitted into each other, and the lenses are aligned in the radial direction by the clearance, and a predetermined lens interval is obtained, and the sector angle or number of the sector-shaped pieces is changed between adjacent lenses, and the lenses are fitted into each other's notches. A lens holding device characterized by a combination of: