JP3459677B2 - Optical system with aperture - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a fixed member and a movable member which are disposed between lenses on the optical axis and sandwich at least two or more diaphragm blades from front and rear in the optical axis direction. is advanced and retracted from the optical path of the diaphragm blades of the relative movement relates an optical system having a stop for performing the opening area adjusting of the optical path.

[0002]

2. Description of the Related Art Conventionally, an iris diaphragm is provided in an optical system.
It is only necessary to have a function of adjusting the aperture diameter of the stop and controlling the amount of light. Therefore, the aperture blades, the fixed member, and the movable member, which are the components of the iris diaphragm, are configured in a shape suitable for only the above functions.

On the other hand, as lens holding means of an optical system,
It is common to screw the holding ring into the lens barrel in the case of a metal lens barrel. In the case of a large cost and space constraint, a so-called C-ring fastening or caulking technique is used.
In the case of a plastic lens barrel in recent years, thermal caulking and plastic caulking are frequently used.

FIG. 5 is a cross-sectional view of a main part showing an optical system having a conventional iris diaphragm. In FIG. 5, 1 and 2 are lenses,
Reference numerals 3 and 4 denote plastic lens barrels as lens holding means.
All the caulked portions 3-1 and 4-1 are plastically deformed, and the chamfered portions 1-1 and 2-1 of the lenses 1 and 2 are pressed to hold the lenses.

[0005] 5-9 is one component of the iris diaphragm unit, 5 fixed honeycomb (fixing member) having a cam stop (not shown) into a concave shape, 6 rotatable windmill (movable portion
And 7 are aperture blades having dowels (not shown) on both surfaces. The dowels on one surface are supported by cams of the Hachinos 5, and the dowels on the other surface are supported by shaft holes (not shown) of the wind turbine 6. This is a general configuration in which the opening diameter is variable by the rotation of the wind turbine. Reference numeral 8 denotes a main plate, on which the above-mentioned Hachinos 5 is fixed, the position of the windmill 6 in the optical axis direction is regulated, and an actuator 9 is mounted.

The above-mentioned Hachinos 5 and wind turbine 6 have edge portions 5-1 and 6-1 on the inner diameter, respectively, and have an effective light beam diameter (optical aperture).
Caliber) . The grain of each edge 5-1 and 6-1
Ri chamfering a for operation hooking prevent the blade 7 side, b is made large than that of the opposite vane end aperture such that less visible from hard or image plane is illuminated in incident light to prevent internal reflection Chamfers c and d have been processed. As a result, the edge portions 5-1 and 6-1 are located in the middle part of the wall thickness near the inner diameter of both the honey nose 5 and the wind turbine 6 for the sake of operation and reduction of internal reflection.

In the above arrangement, the lens barrels 3 and 4 have the lenses 1 and 2 attached thereto.
When the inside of the lens barrel is fixed and assembled, since the space between the lenses 1 and 2 is near the stop position, it is inevitably easily illuminated by incident light, and the edge portions 5 of the Hachinos 5 and the windmill 6 -1,6-1, produce internal reflection at the edge 3-2 and the like are effective light flux diameter proximate <br/> portion position of the body with side of the lens barrel 3, the secondary light sources (the so-called mechanical reflection ghost source) Become. Therefore, when observed from the emission side, a high-luminance portion is visually observed in a three-row halo shape.

Further, each crimping chamfered portion 1 of the lenses 1 and 2 is used.
1,2-1, if the chamfer is completely covered,
The innermost portion of the caulking margin is likely to be slightly wavy or jagged, and it is difficult to manage the shape beautifully and circularly.

Furthermore, the amount of crimping deformation tends to fluctuate due to variations in the wall thickness dimensions and lens barrel dimensions of the lenses 1 and 2, and the chamfers 1-1 and 2-1 of the lenses 1 and 2 cannot be covered. There is. In this case, since the chamfered portion 1-1 and 2-1 of the lenses 1 and 2 is a ground-glass diffusion surface, covered it becomes diffusion light source shows through have not portions, when viewed lens barrel, halo And it is inferior in quality. At the same time, this is a factor that lowers the contrast of the image on the image plane.

[0010]

[0009] In addition to the conventional example shown in FIG.
Because of the use of a lens holding means such as a press ring, there are the following problems.

1) Caulking: This is the most advantageous in terms of cost. In the case of the lens assembled last in the lens unit, it fits in a small space due to the product shape. It is difficult to disassemble the lens and the serviceability such as cleaning is poor.

B. Edge shape after crimping is not smooth, also difficult to manage the uniform diameter, the lens barrel
Poor quality and edge reflections when viewed .

C. Caulking tools (spin rollers, heated pieces,
When a space for applying an ultrasonic vibration horn is required, and when a plurality of lenses are continuously caulked from one direction, the “diameter difference” for sequentially increasing the diameters must be increased.

2) C-ring stopper: A space-saving configuration is possible compared to the case of caulking using a caulking tool. Since the retaining ring has a C-shape, unnecessary light rays can pass through a cut portion larger than the inner diameter of the ring, thereby increasing internal reflection and deteriorating the optical performance and the quality of the lens interior.

B. Since the C-ring itself has a circular cross section, it is difficult to prevent reflection.

3) Pressing ring: A true circular opening shape is obtained.
Good service, but A. B. Since it is a separate part, the cost inevitably increases, and space is also required. In the case of screwing, machining is required for the lens barrel and holding ring,
The cost increases. When a screw portion is formed during molding, the use of a slide mold increases the mold manufacturing cost. In the case of rotational punching, the mold release time is long and the molding cost is increased.

An object of the present invention is to provide an optical system having a stop that solves the above problems.

[0018]

An optical system having an aperture according to the present invention is provided between a lens on an optical axis and has a fixed member and a movable member which sandwich at least two or more aperture blades from front and rear in the optical axis direction. in by forward and backward movement of the diaphragm blades into the optical path by the relative movement between the fixed member and the movable member has an optical system having a stop for performing the opening area adjusting of the optical path, the fixing member, at least one of the effective movable member By forming the light beam diameter proximity part close to the stop-side surface of the lens at the nearest position and defining the optical aperture diameter at the lens surface, light shielding caused by the lens adjacent to the stop,
The problems relating to internal reflection, internal quality, and optical performance could be reduced without adding new members. Further, it is possible to obtain an optical system of the same quality as holding the lens using a holding ring which is advantageous in cost, and to expand the degree of freedom in design.

[0019]

[Embodiment 1] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a main cross-sectional view of an optical element arrangement showing a wide state of a short zoom type optical system according to a first embodiment of the present invention.
In FIG. 1, I is a first lens barrel, II is a second lens barrel, III
Indicates only the third lens unit. A is the optical axis, B is the focal plane,
C is an optical path corresponding to a photographing light flux among rays back-projected from the outermost diameter portion F of the image circle of the present optical system, and D is an optical path reaching the vicinity of the iris diaphragm in the same manner. Members on this optical path are as follows. This indicates that it can be seen from the focus side.

FIG. 2 is an enlarged view of a main part of FIG.
Have the same reference numerals are given to the conventional optical system the same parts as shown in
You. That is, in FIG. 2, 1 and 2 are lenses. 3 and 4
A plastic barrel caulking as a lens holding means
Parts 3-1 and 4-1 are plastically deformed,
Press the chamfers 1-1 and 2-1 to hold the lenses 1 and 2.
ing. 5 to 9 are constituent members of the iris diaphragm, and 5 is a fixed member.
Fixed Hachinos (fixed member), 6 is a rotatable windmill (movable
), 7 are aperture blades , and 8 is a main plate. Example 1
Means that the configuration of the lens 1 is the same as that of the conventional example,
This prevents harmful light and improves the appearance of the holding portion.

Edge portion of wind turbine 6 (effective beam diameter proximity member)
6-1 on the aperture-side surface 2a of the lens 2 at the closest position.
Close to define the optical aperture diameter on the lens surface 2a
Like that. That is, even if the dimension of the edge portion 6-1 varies with respect to the arc surface of the lens 2,
To define an effective optical path on the range next and optical design values it does not abut in the effective light beam, are arranged close to the lens 2.

The lens 2 side of the wind turbine 6 is an optical axis.WhenVertical plane
6-4And the tapered surface on the diaphragm blade 7 side6-5
Is the back projection optical path D (the tapered surface is the most visible in the entire zoom range).
(The light path at the wide end is cheaper.)
And focus surfaceBIn the image cycle
It is provided at the minimum required angle.

The lens 2 is the same as the conventional example in that it is assembled from the diaphragm blade 7 side. In the first embodiment, however, the lenses 10 and 11 are assembled first in the same direction, and both are caulked before the lens 2 is caulked. ( Part 4-3 of the lens barrel 4 in the figure is shown in a shape before plastic deformation).

Since the fitting diameters of the lenses 2, 10 and 11 are close to each other, it is difficult to provide a deformed portion on the entire circumference. Therefore, in the first embodiment, the lens barrel 4 is formed in such a shape that the hatched portion 4-2 is equally removed at three locations of 60 ° in the entire circumference, and caulking of the two locations 4-1 and 4-3 is performed. I have both. Accordingly, since there is no member that covers the chamfer 2-1 of the lens 2 in the range of the removal portion, the shape of the wind turbine 6 prevents the illumination from being illuminated from the incident side.

Embodiment 2 FIG. FIG. 3 is a main cross-sectional view of an optical system showing a second embodiment of the present invention.
The harmful light is reduced for both of the two holding lens barrels 3 and 4, and the same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

The edge portion 6-1 of the windmill 6 is provided so as to coincide with the effective optical path (envelope surface) G and close to the lens 1, and the edge portion 3-2 of the lens barrel 3 is positioned on the focus plane. It is not visible from inside the circle.

Further, the tapered surface 6-2 starting from the edge portion 6-1 of the wind turbine 6 is formed so as to be far from the effective optical path G toward the diaphragm blade 7 in order to make it difficult to receive the illumination surface from the incident side. . The edge portion 5-1 of the Hachinos 5 has a configuration similar to that of the wind turbine 6 in the first embodiment, and the caulked portion 4 of the lens barrel 4 is used.
-1 and the incident light on the chamfer 2-1 of the lens 2 are prevented from being illuminated (that is , shadowed on the edge portion 5-1 ), and harmful light and a reduced appearance of the inner periphery of the caulked portion (jagged) (Easy) part is prevented.

Embodiment 3 FIG. FIG. 4 is a main cross-sectional view showing the third embodiment, in which lenses 2, 10, and 11 in the first embodiment are so-called C-rings 12, 1.
3, the C-ring 12 is placed in the shadow of the edge 6-1 of the windmill 6, and the second edge 6-3 is also provided on the diaphragm blade 7 side.

[0029]

As described above, according to the present invention, at least one of the effective light flux diameters of the fixed member and the movable member is brought into close proximity to the diaphragm-side surface of the lens located closest to the lens surface. Is formed so as to define the optical aperture diameter of the lens. Therefore, of the losses caused by the lens holding means with respect to the lens adjacent to the stop, 1) -B, 2) -A,
The problem described in B can be reduced without increasing the manufacturing cost (without additional components).

Thus, the optical system having the same light-shielding, inner-surface reflection, in-view quality, and optical performance as the case of holding the lens using the holding ring is used. Etc. can be achieved, cost,
There is an effect that the degree of freedom in design can be increased with respect to space restrictions and the like.

Also, between the lenses sandwiching the aperture blade,
Each of the lens barrels and the windmill, the Hachinos, and the diaphragm blades have a total of five effective diameter proximity parts, and even if they are edged to reduce internal reflection, they are observed in five halo shapes. Although it was general, for each one place on the lens barrel side,
The effect of removing the halo-shaped harmful light source and reducing and improving the effective diameter adjacent portion observed in five halo locations to three locations can be obtained.

[Brief description of the drawings]

FIG. 1 is a main sectional view of an optical element arrangement diagram showing a wide state of a short zoom type optical system to which a first embodiment of the present invention is applied.

FIG. 2 is an enlarged view of a main part of FIG. 1;

FIG. 3 is an enlarged view of a main part showing a second embodiment of the present invention.

FIG. 4 is an enlarged view of a main part showing a third embodiment of the present invention.

FIG. 5 is a main sectional view showing a conventional optical system.

[Explanation of symbols]

1,2,10,11 lens 3,4 lens barrel 5 Hachinos 5-1 Edge part 6 windmill 6-1 Edge part 7 Aperture blade G Effective optical path on optics

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03B 9/00-9/70 G02B 7/02

Claims (10)

(57) [Claims] 1. A fixed member and a movable member which are arranged between lenses on the optical axis and sandwich at least two or more blades from front and rear in the optical axis direction, the blades being moved by relative movement between the fixed member and the movable member. In an optical system having an aperture for adjusting the opening area of the optical path by moving the optical path into and out of the optical path, at least one of the effective light flux diameter adjacent portions of the fixed member and the movable member is provided on the aperture-side surface of the lens at the nearest position. An optical system having a stop formed so as to define an optical aperture diameter in the lens surface in close proximity to the lens. 2. An optical system having an aperture according to claim 1, wherein the lens at the nearest position is held at a constant distance from the aperture on the optical axis. 3. A lens in which the aperture diameter of the stop is brought close to the lens is incorporated into the lens barrel from the stop side, leaving an opening shape in which at least a part is larger than the effective diameter of the lens surface on the stop side. 3. An optical system having a diaphragm according to claim 1, wherein said optical system is fixed by lens holding means. 4. The optical system according to claim 3, wherein said lens holding means is a C-ring. 5. The optical system according to claim 3, wherein said lens holding means is caulked by plastic deformation of a lens barrel. 6. The optical system having an aperture according to claim 5, wherein said crimping is thermal crimping or ultrasonic crimping for a plastic lens barrel. 7. The optical system according to claim 6, wherein the caulking is partial caulking. 8. The effective light beam diameter proximity portion provided on the side closer to the aperture blade in addition to the effective light beam diameter proximity portion near the lens. An optical system having the stop according to the item. 9. An effective means provided on a side close to said diaphragm blade.
The light flux diameter proximity part is provided on the movable member side
An optical system having a stop according to claim 8, wherein: 10. An optical system having a stop according to claim 1, wherein an iris stop is used as said stop.