JPH0961686A - Plastic lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily hold a plastic lens without providing a lens chamber by providing an engaging member for directly engaging with the inner periphery part of a lens barrel on the peripheries of respective incident and emitting surfaces, and causing the engaging part to covert the relative rotational force of the lens barrel and the plastic lens to driving force in the optical axis direction of the plastic lens. SOLUTION: The plastic lens L is assembled in the lens barrel 4 so that the optical axis of the lens L may be aligned with the optical axis AX of an optical system. Therefore, the engaging part of the lens L is directly engaged with the inner periphery part of the lens barrel 4, whereby the lens L is held by the lens barrel 4. As a lever 6 is rotated by a driving motor 7, the lens L is rotated around the optical axis AX with reference to the lens barrel 4. As a result, the spiral recessed and projected part 5 of the inner periphery part of the lens barrel 4 is meshed with the recessed and projecting part of the engaging part of the lens L, so that the lens L is moved along the optical axis AX while rotating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic lens, and more particularly to a plastic lens that can be easily held and driven.

[0002]

2. Description of the Related Art A conventional plastic lens is fixed in a lens chamber and is held by a lens barrel through this lens chamber. Therefore, when the plastic lens is driven along the optical axis, by rotating the lens barrel, the lens chamber is moved in the optical axis direction by the guidance of the helicoid (spiral uneven portion) provided in the lens barrel. . The plastic lens is usually moved in the optical axis direction along with the movement of the lens chamber in the optical axis direction.

[0003]

As described above, the conventional plastic lens is held in the lens barrel while being fixed in the lens chamber. Therefore, the required diameter of the entire lens barrel increases, and the weight tends to increase. As a result, the manufacturing cost becomes high, and the workload in driving the lens is large, which causes a load on the drive mechanism.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a plastic lens which is easy to hold and drive a lens without providing a lens chamber.

[0005]

In order to solve the above-mentioned problems, in the present invention, in a plastic lens to be incorporated in a lens barrel, the lens barrel is provided on the periphery of the entrance surface and the exit surface. An engaging portion for directly engaging with the inner peripheral portion of the plastic lens is provided, and the engaging portion converts a relative rotational force between the lens barrel and the plastic lens into a driving force in the optical axis direction of the plastic lens. A plastic lens characterized by being formed as described above.

According to a preferred aspect of the present invention, the engaging portion has an uneven portion formed so as to mesh with a spiral uneven portion formed on the inner peripheral portion of the lens barrel. Further, it is preferable that the engaging portion is formed substantially symmetrically with respect to a lens optical axis defined by the entrance surface and the exit surface.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION For example, JP-A-61-2155.
Japanese Patent Publication No. 10 discloses a plastic lens having an outer peripheral portion on the periphery of the entrance surface and the exit surface. This publication proposes a structure in which a space ring and a lens chamber are omitted by fixing a plastic lens to a lens barrel through its outer peripheral portion.

In this case, if the plastic lens is fixed to the lens barrel and it is not necessary to drive the lens,
Certainly, the lens chamber can be omitted, which is advantageous. However, the lens chamber cannot be omitted when the plastic lens has to be driven in the optical axis direction with respect to the lens barrel. That is, it is necessary to fix the plastic lens in the lens chamber and drive the lens chamber integrally with the plastic lens in the optical axis direction with respect to the lens barrel.

As described above, in the plastic lens of the present invention, the engaging portions for directly engaging with the inner peripheral portion of the lens barrel are provided on the peripheral edges of the entrance surface and the exit surface.
The engaging portion is formed so as to convert the relative rotational force between the lens barrel and the plastic lens into a driving force in the optical axis direction of the plastic lens. Therefore, the plastic lens can be directly held by the lens barrel without providing the lens chamber, and the plastic lens can be driven in the optical axis direction by relatively rotating the lens barrel and the plastic lens.

As described above, in the structure of the present invention, since the lens chamber is not required, the lens can be easily held and the diameter and weight of the entire lens barrel can be reduced.
As a result, the work amount (= weight × driving amount) in driving the lens becomes small, and the lens can be easily driven without applying an excessive load to the driving mechanism.

As a concrete structure of the engaging portion, an outer helicoid (spiral uneven portion) formed on the inner peripheral portion of the lens barrel and an inner helicoid (spiral uneven portion) formed on the engaging portion. It is conceivable that the plastic lens is driven in the optical axis direction in accordance with the relative rotation between the lens barrel and the plastic lens by engaging with the concave and convex portions formed so as to mesh with the portion. In this case, if the engaging portion of the plastic lens is formed substantially symmetrical with respect to the lens optical axis, the configuration can be further simplified.

Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a sectional view schematically showing the structure of a plastic lens according to the first embodiment of the present invention. Also,
FIG. 2 is a sectional view showing a state in which the plastic lens of FIG. 1 is incorporated in a lens barrel.

In the plastic lens L of FIG. 1, an engaging portion 3 is formed on the periphery of an entrance surface 1 on which a light beam enters and an exit surface 2 on which a light beam exits. On the other hand, in FIG.
The plastic lens L is incorporated in the lens barrel so that the lens optical axis ax of the plastic lens L of (1) coincides with the optical axis AX of the optical system. In this state, the engaging portion 3 of the plastic lens L is directly engaged with the inner peripheral portion of the lens holding portion 4, so that the plastic lens L is held by the lens barrel.

As shown in FIG. 2, the lens barrel 4
A spiral concave-convex portion 5 centered on the optical axis AX is formed on the inner peripheral portion (shown by the hatched portion in the drawing). Further, the engaging portion 3 of the plastic lens L is formed with an uneven portion 3a adapted to mesh with the spiral uneven portion 5 of the lens barrel 4. Further, the plastic lens L is configured to be rotationally driven about the optical axis AX by the rotating action of the lever 6 driven by the drive motor 7 about the optical axis AX.

Thus, the plastic lens L rotates with respect to the lens barrel 4 about the optical axis AX as the lever 6 is rotated by the drive motor 7. As a result, due to the meshing of the spiral concave-convex portion 5 formed on the inner peripheral portion of the lens barrel 4 and the concave-convex portion 3a formed on the engaging portion 3 of the plastic lens L, the plastic lens L moves along the optical axis AX. While rotating about the center, the spiral concave-convex portion 5 guides and moves along the optical axis AX.

FIG. 3 is a diagram schematically showing the construction of a plastic lens according to the second embodiment of the present invention,
(A) is a front view of a plastic lens, (b) is sectional drawing which followed the line ABC of (a). In the plastic lens L of FIG. 3, the edges 8 of the lens effective surface, the pair of engaging portions 9, and the lever 10 are formed on the periphery of the entrance surface 1 and the exit surface 2. The pair of engaging portions 9
Are formed at positions symmetrical with respect to the lens optical axis ax.

FIG. 4 is a diagram showing a state in which the plastic lens L of FIG. 3 is incorporated as an eyepiece lens in the real image type finder optical system of the camera. FIG. 5 is a diagram schematically showing the configuration of the real image type finder optical system of FIG. The real image type finder optical system in FIG. 5 is composed of an objective lens system 11 and an eyepiece lens 13 in order from the object side.

Therefore, in the real image type finder optical system of FIG. 5, the light from the subject forms an intermediate image of the subject on the image forming surface 12 via the objective lens system 11. The intermediate image of the subject is visually observed by the eyepiece lens 13 including the plastic lens L shown in FIG. At this time,
Diopter adjustment is performed by appropriately moving the eyepiece lens 13 back and forth along the optical axis AX as indicated by arrow F1 in the figure.

Referring to FIG. 4, the plastic lens L
Is the optical axis A of the real image type finder optical system.
A plastic lens L is incorporated in the real image type finder optical system so as to coincide with X. In the real image finder optical system, the plastic lens L is held by the lens barrel 15. A spiral concave-convex portion (not shown) is formed on the inner peripheral portion of the lens barrel 15, and the concave-convex portion 9a of the engaging portion 9 meshes with the spiral concave-convex portion.

The tip of the lever 10 projects outward from the opening of the finder frame 14. Therefore,
By rotating the lever 10 as shown by an arrow F2 in the figure, the plastic lens L can be rotated about the optical axis AX. As a result, the lens barrel 1
The spiral concave and convex portions formed on the inner peripheral portion of 5 and the concave and convex portions 9a formed on the engaging portion 9 of the plastic lens L cause the plastic lens L to rotate while rotating around the optical axis AX. Axis AX
Move along.

In each of the above-described embodiments, the spiral concave and convex portions formed on the lens barrel and the concave and convex portions formed on the engaging portion of the plastic lens are engaged with each other.
However, the configuration of the engaging portion of the plastic lens is
The present invention is not limited to the above embodiments. Therefore, for example, a follower pin may be formed in the engaging portion of the plastic lens, and the plastic lens may be guided in the optical axis direction according to the rotation of the cam in accordance with the straight-ahead key inside the lens barrel.

[0022]

As described above, according to the present invention, it is possible to realize a plastic lens that is easy to hold and drive the lens without providing a lens chamber.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing a configuration of a plastic lens according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state in which the plastic lens of FIG. 1 is incorporated in a lens barrel.

FIG. 3 is a diagram schematically showing a configuration of a plastic lens according to a second embodiment of the present invention, (a) is a front view of the plastic lens, and (b) is a line A- of (a). B
It is sectional drawing along -C.

FIG. 4 is a diagram showing a state in which the plastic lens L of FIG. 3 is incorporated as an eyepiece lens in a real image type finder optical system of a camera.

5 is a diagram schematically showing a configuration of a real image type finder optical system in FIG.

[Explanation of symbols]

 1 Entrance Surface 2 Exit Surface 3,9 Engagement Part 4,15 Lens Barrel 5 Spiral Concavo-convex Part 6,10 Lever 7 Drive Motor 8 Edge Part 11 Objective Lens System 12 Image Forming Surface 13 Eyepiece 14 Viewfinder Frame L Plastic Lens AX optical axis ax lens optical axis

Claims (3)

[Claims] 1. A plastic lens adapted to be incorporated in a lens barrel, wherein an engaging portion for directly engaging with an inner peripheral portion of the lens barrel is provided on the periphery of an entrance surface and an exit surface. The plastic lens, wherein the engaging portion is formed so as to convert a relative rotational force between the lens barrel and the plastic lens into a driving force in the optical axis direction of the plastic lens. 2. The engaging portion has an uneven portion formed so as to mesh with a spiral uneven portion formed on an inner peripheral portion of the lens barrel. Plastic lens. 3. The plastic lens according to claim 1, wherein the engaging portion is formed substantially symmetrically with respect to a lens optical axis defined by the entrance surface and the exit surface.