JP3384239B2 - Three eccentric lens holding structure and three eccentric lens positioning method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure and method for positioning and holding three decentering lenses in a lens barrel when using the decentering lenses in an optical device.

[0002]

2. Description of the Related Art Generally, when a lens is held in a lens barrel, the lens barrel is shaped so that the axis of the lens barrel is aligned with the centering axis of the objective lens. Given. Therefore, in the case of a lens barrel holding a plurality of lenses, it cannot be held in a single lens barrel unless the centering axes of all the lenses held therein match. Normally, if the lens has a so-called axially symmetric shape where two spherical lens surfaces are given with one common axis, the centering axes of all the lenses are It is possible to fit on one common axis and thus keep the lenses in one barrel.

By the way, when an optical system is constructed by incorporating a decentering lens into a plurality of lenses held in a lens barrel, in particular, the centering axis of the decentering lens with respect to the axis of the lens barrel is used. No convenient technique has yet been established for holding this decentered lens when attempting to tilt and hold.

The present invention has been made in view of the above-mentioned technical problems so as to effectively solve them. That is, the present invention provides a decentering lens holding structure in which the decentering axis of one decentering lens of the three lenses held in the lens barrel can be tilted with respect to the common centering axis of another decentering lens, and A positioning method is provided.

[0005]

A three decentering lens holding structure according to the present invention holds and holds three decentering lenses each having two lens surfaces provided with mutually different axes of symmetry in a lens barrel. Therefore, in the decentering lens holding structure, the lens barrel includes a first lens barrel that directly holds two first and second decentering lenses arbitrarily selected from the decentering lens, and another third decentering lens. The second lens barrel holds the lens and is housed in the first lens barrel to indirectly and fixedly hold the third decentering lens in the first lens barrel. In the decentering lens, the centering axes determined by using any one of the lens surfaces as a reference lens surface are matched, and the matched common centering axis is further matched with the axis of the first lens barrel. It is arranged to. The first and second decentering lenses have first and second annular flat surfaces that are stepped with respect to the lens surfaces opposite to the reference lens surfaces, respectively.
The annular flat surface and the second annular flat surface are orthogonal to the common centering axis, and the first lens barrel has the first
And a second decentering lens so as to support the first and second decentering lenses, respectively. The first decentering lens has a reference lens surface. Alternatively, either the first annular flat surface or the first annular flat surface
The second decentering lens is supported by the lens receiving portion and abuts against the first fixing means on the other surface so as to be sandwiched between the first lens receiving portion and the first fixing means, and the second decentering lens is the reference lens thereof. The second surface on either the surface or the second annular flat surface.
The third decentering lens is supported by the lens receiving portion, and is held between the second lens receiving portion and the second fixing means by being brought into contact with the second fixing means on the other surface, and the third decentering lens is any one of them. The centering axis determined by using one lens surface as a reference lens surface is arranged so as to coincide with the axis of the second barrel, and the third decentering lens is provided on the lens surface opposite to the reference lens surface. On the other hand, there is provided a third annular flat surface having a step, the third annular flat surface is orthogonal to the centering axis of the third decentering lens, and the second lens barrel is the first lens barrel. The third decentering lens is provided with a third lens receiving portion projecting radially inward from the inner peripheral surface of the decentering lens so as to support the decentering lens. One of them is supported by the third lens receiving portion, and the other surface is fixed to the third fixing means. By being contact preferably it is sandwiched between the third lens receiving portion and the third fixing means. Further, it is preferable that the axis of the second lens barrel be tilted at a predetermined angle with respect to the axis of the first lens barrel.

Further, the three decentering lens positioning method of the present invention is a three decentering lens for positioning three decentering lenses each having two lens surfaces having different axes of symmetry. The method of positioning the
Holds the 1st and 2nd decentering lenses directly on the 1st lens barrel
And hold other third decentering lens directly fixed
Holding the second lens barrel inside the first lens barrel,
Among the centers of curvature of the four lens surfaces in the second decentering lens, a straight line connecting the centers of curvature arbitrarily selected from the decentering lenses is used as the common centering axis of these two decentering lenses, and The common centering axis is the first
These two decentering lenses are arranged so as to be aligned with the axis of the lens barrel, and the remaining third decentering lens is arranged in the second lens barrel so that its centering axis is aligned with the axis of the second lens barrel. To place. Further, the second lens barrel is housed in the first lens barrel so that their respective axial centers are tilted by a predetermined angle, so that the centering axes of the third decentering lens have the first and second decentering axes. It is preferably tilted by said predetermined angle with respect to the common centering axis of the lenses.

In the decentering lens, as shown in FIG. 2, two non-axisymmetric lens surfaces A and B are provided.
For example, the centering axis when the lens surface A is the reference lens surface is determined as follows. When the center of curvature of the lens surface A is C _A , the effective optical path area on the lens surface A is D _A , and the effective optical path area on the lens surface B is D _B , any area on the lens surface A including the area D _A inside the center of the circle P (see FIG. 3) and C _S, a circle a line L connecting the C _a and C _S as the axis P
If the region D _B is also included inside the cylinder S including, the straight line L can be used as the centering axis. That is, considering a cylinder that includes the effective optical path regions of both lens surfaces, and setting the cylinder so that the axis of the cylinder passes through the center of curvature of one lens surface, the axis of the cylinder that satisfies such conditions Can all be centering axes. Therefore, although the centering axes can be set innumerably, one of them is actually selected so that the positional relationship with other lenses is optimized in consideration of the configuration of the entire optical system including the decentering lens. It is set as the centering axis.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of three decentering lens holder structures according to the present invention. In the figure, 10 is a first decentering lens, 20 is a second decentering lens, 30 is a third decentering lens, 40 is a first lens barrel, and 50 is a second lens barrel.

The first decentering lens 10 has a first lens surface 11 and a second lens surface 12 which are respectively provided as convex curved surfaces. The centers of curvature of the first lens surface 11 and the second lens surface 12 are points C ₁₁ and C ₁₂ . The subscript numbers correspond to the reference numerals of the respective lens surfaces. The centering axis of the first decentering lens 10 is determined with the first lens surface 11 as a reference lens surface, that is, the first lens surface 1
The centering axis L ₁₁ is given by a straight line connecting the center point P _{11 of} 1 and the center of curvature C ₁₁ .

The first decentering lens 10 has a second lens surface 12
The peripheral portion is annularly removed from the side in the direction along the centering axis L ₁₁ , and by the removal, the radially flat first annular surface 14 forms a step with respect to the second lens surface 12. Is formed in. And this first annular flat surface 14
Lies in a plane orthogonal to the centering axis L ₁₁ . Therefore, the first annular flat surface 14 has an axially symmetric shape with respect to the centering axis L ₁₁ . Further, the first lens surface 11 is
Since the center of curvature C ₁₁ exists on the centering axis L ₁₁ ,
It is axisymmetric with respect to this centering axis L ₁₁ . in this way,
The lens 10 is an eccentric lens, but faces the opposite directions because the lens is sandwiched in the thickness direction by its peripheral portion, as in the case where an axially symmetric lens is normally held in the lens barrel. It has two axisymmetric surfaces. The removed portion may be obtained by processing such as polishing,
The lens may be molded from the beginning during molding.

The second decentering lens 20 has a third lens surface 21 provided by a convex curved surface and a fourth lens surface 22 provided by a concave curved surface. Third lens surface 21 and fourth
The centers of curvature of the lens surface 22 are points C ₂₁ and C ₂₂ . The centering axis of the second decentering lens 20 is determined with the third lens surface 21 as a reference lens surface, that is, the centering axis is a straight line connecting the center point P ₂₁ of the third lens surface 21 and the center of curvature C _21. L ₂₁ is given. The second decentering lens 20 is also the first
Similar to the decentering lens 10, the peripheral portion is annularly removed from the fourth lens surface 22 side in the direction along the centering axis L ₂₁ , and the removal eliminates the radial second flat annular surface 24.
Are formed so as to form a step with respect to the fourth lens surface 22. The second annular flat surface 24 lies in a plane orthogonal to the centering axis L ₂₁ . That is, the second annular flat surface 24 also has an axially symmetric shape with respect to the centering axis L ₂₁ , and the center of curvature C _{21 of} the third lens surface 21 also lies on the centering axis L _21. It is axisymmetric with respect to the centering axis L ₂₁ . As described above, the second decentering lens 20 is also sandwiched in the thickness direction by the peripheral edge portion of the second decentering lens 20, as in the case where the lens having the axially symmetrical shape is normally held in the lens barrel, and thus the second decentering lens 20 is moved in the opposite direction. It has two axisymmetric faces facing each other.

First decentering lens 10 and second decentering lens 2
0 is, as shown in the drawing, the respective centering axes L ₁₁ and L _21.
Are aligned with each other (hereinafter referred to as the common centering axis L _C ), and the common centering axis L _C is aligned with the axis of the first lens barrel 40. As a result, the center of curvature C ₁₂ of the second lens surface 12 which is not the reference lens surface in the first decentering lens 10 and the center of curvature C ₂₂ of the fourth lens surface 22 which is not the reference lens surface in the second decentering lens 20 are , Is located at a position off the common centering axis L _C.

The first lens barrel 40 has a ring-shaped first lens receiving portion 41 and a second lens receiving portion 41 which project radially inward from the inner peripheral surface thereof.
The lens receiving portion 42 is formed. In this embodiment, the peripheral edge portion of the first lens surface 11 of the first decentering lens 10 is the first lens receiving portion 41, and the peripheral edge portion of the third lens surface 21 of the second decentering lens 20 is the second lens receiving portion 41. Four
It is supported by 2. Further, the first fixing washer 61 is provided on the first annular flat surface 14 of the first decentering lens 10, and the second fixing washer 62 is provided on the second annular flat surface 24 of the second decentering lens 20. Abut. Washers 61,62
Contacts the annular flat surfaces 14 and 24 so as to press the decentering lenses 10 and 20 against the lens receiving portions 41 and 42, and is fixed to the lens barrel 40. As a result, the first and second The decentering lenses 10 and 20 are fixedly held by being sandwiched between the lens receiving portions 41 and 42 of the lens barrel 40 and the washers 61 and 62. These washers 61,
As the lens fixing means instead of 62, for example, a ring-shaped member having an outer screw threaded to the inner peripheral surface of the lens barrel can be used.

Generally, in a decentered lens, the lens thickness is not constant over the surroundings, so it is impossible to hold such a lens in the lens barrel by the conventional method of holding an axisymmetric lens. By setting the reference lens surface to determine the centering axis and forming an annular flat surface orthogonal to this centering axis, any decentered lens can be easily inserted into the lens barrel in the axial direction. Can be held to regulate movement to.

The third decentering lens 30 has a fifth lens surface 31 provided with a convex curved surface and a sixth lens surface 32 provided with a concave curved surface. Fifth lens surface 31 and sixth
The centers of curvature of the lens surface 32 are points C ₃₁ and C ₃₂ . The centering axis of the third decentering lens 30 is determined with the fifth lens surface 31 as a reference lens surface, that is, the centering axis is a straight line connecting the center point P ₃₁ of the fifth lens surface 31 and the center of curvature C _31. L ₃₁ is given. Similarly to the first decentering lens 10 and the second decentering lens 20, the third decentering lens 30 has a peripheral portion removed from the sixth lens surface 32 side in an annular shape in the direction along the centering axis L ₃₁ , and A third annular surface 34 that is flat in the radial direction due to the removal is formed so as to form a step with respect to the sixth lens surface 32. The third annular flat surface 34 lies in a plane orthogonal to the centering axis L ₃₁ . That is, the third annular flat surface 34 also has an axially symmetric shape with respect to the centering axis L ₃₁ , and the fifth lens surface 31 has its center of curvature C _{31 on the} centering axis L _31. It is axisymmetric with respect to the centering axis L ₃₁ . in this way,
The third decentering lens 30 also has two axially symmetrical lenses, which are oriented in opposite directions to each other because the lens is sandwiched in the thickness direction by the peripheral edge thereof, as in the case where the lens is normally held in the lens barrel. It has an axisymmetric surface.

The third decentering lens 30 is the first decentering lens 1.
0 and the second decentering lens 20 are fixedly held in the first lens barrel 40, the centering axis L ₃₁ thereof is made to coincide with the axis of the second lens barrel 50, and the second lens barrel 50 is made. It is fixedly held inside. In the figure, 51 is a third lens receiving portion, and 63
Is a third fixing washer.

As shown, the third decentering lens 30 has a second
It is held in the first lens barrel 40 while being held in the lens barrel 50.

In the second lens barrel 50, the end faces 52, 53 at the peripheral edges of the openings at both ends in the axial direction are inclined with respect to the axis of the second lens barrel 50 itself (the same as the centering axis L _{31 in the} drawing). Has been. Reference numeral 43 in the drawing denotes an annular protrusion that supports the first decentering lens 10 by the first lens receiving portion 41 and also supports the second lens barrel 50 by abutting against the end surface 52 thereof, and 64 is the second mirror. The end face 5 is pressed so that the cylinder 50 is pressed against the annular protrusion 43.
3 is an annular fixing plate that is in contact with 3. The annular fixing plate 64 is fixed to the inner peripheral surface of the first barrel 40. End face 52
Since the abutting surface of the annular protruding portion 43 that abuts with is given so as to be orthogonal to the axis of the first lens barrel 40, the second surface is inclined by the inclination angle of the end surface 52 of the second lens barrel 50. The axis of the lens barrel 50 is tilted with respect to the axis of the first lens barrel 40. The tilt angle in this embodiment is given by θ. Therefore, the centering axis L ₃₁ of the third decentering lens 30 is inclined by the angle θ with respect to the common centering axis L _{C of} the first decentering lens 10 and the second decentering lens 20. The tilt angle θ is an angle that is preset based on the design of the entire optical system including the first to third decentering lenses 10, 20, and 30, and both end surfaces 52 of the second lens barrel 50 corresponding to the angle. , 53 are given.

With the above construction, the assembly of the second lens barrel 50 to the first lens barrel 40 is as easy as an ordinary lens, and only a specific decentering lens has its centering axis set to another decentering lens. It is easy to configure the optical system so that it is tilted with respect to the centering axis.

In the above example, the centering axis of the decentering lens arranged in the center among the three decentering lenses is tilted with respect to the common centering axis of the decentering lenses at both ends. The position of the decentered lens to be tilted can be arbitrarily selected depending on the position where the second lens barrel is stored. In the present invention, the structure for holding the three decentering lenses has been described in detail, but in the case of holding more decentering lenses,
It can be configured with the same technical idea.

[0021]

According to the three decentering lens holding structure of the present invention, each of the four centers of curvature of a total of four lens surfaces in any two first and second decentering lenses of the three decentering lenses, respectively. A straight line connecting the centers of curvature selected one by one from the decentering lens is used as the common centering axis of these two decentering lenses, and this common centering axis is
These two decentering lenses are arranged so as to coincide with the axial center of the first lens barrel, and the remaining third decentering lens is arranged so that its centering axis coincides with the axial center of the second lens barrel. And the second lens barrel is housed in the first lens barrel so that their axial centers are tilted by a predetermined angle, the centering axes of the third decentering lens are The three decentering lenses can function as an accurate optical system because they can be positioned so as to be tilted by the predetermined angle with respect to the common centering axis of the decentering lens and fixedly held in the lens barrel. it can.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a lens holding barrel according to the present invention.

FIG. 2 is a diagram for explaining how to set a centering axis of a decentering lens.

FIG. 3 is a diagram illustrating a method of setting a centering axis of a decentering lens.

[Explanation of symbols]

10 1st decentering lens 11 1st lens surface 12 2nd lens surface C ₁₁ 1st lens surface curvature center C ₁₂ 2nd lens surface curvature center P ₁₁ 1st lens surface center point L ₁₁ 1st decentering lens center Shaft 14 First annular flat surface 20 Second eccentric lens 21 Third lens surface 22 Fourth lens surface C ₂₁ Center of curvature of third lens surface C ₂₂ Center of curvature of fourth lens surface P ₂₁ Center point of third lens surface L ₂₁ Centering axis of second eccentric lens L _C Common centering axis of first eccentric lens and second eccentric lens 24 Second annular flat surface 30 Third eccentric lens 31 Fifth lens surface 32 Sixth lens surface C ₃₁ 5 Center of curvature of lens surface C ₃₂ Center of curvature of sixth lens surface P ₃₁ Center point of fifth lens surface L ₃₁ Centering axis of third eccentric lens 34 Third annular flat surface 40 First lens barrel 41 First lens receiver Portion 42 Second lens receiving portion 43 Annular protrusion 50 Second lens barrel 51 Third 'S receiving unit 52 second opening peripheral end surface 61 the washer of the opening peripheral end face 53 second barrel of the lens barrel 62 Washer 63 Washer 64 annular fixing plate

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Claims (5)

(57) [Claims] The method according to claim 1] Three eccentric lens having two lens surface symmetry axis is given different from each other, respectively, a decentered lens holding structure for fixing and holding in a lens barrel, the barrel, the eccentric first holding directly fixing the two first and second eccentric lenses that are selected arbitrarily from the lens
A lens barrel, by being housed in the first lens barrel which holds the other third eccentric lens, the third eccentric lenses first
Consists of a second barrel indirectly fixed and held in a lens barrel, the first and second eccentric lens is heart-up shaft that is determined each one lens surface either as reference lens surface
As but consistent, and common cardiac-up shaft that its matching <br/> are arranged so as to further match the axis of the first lens barrel
Holding structure of the three eccentric lenses, characterized in that there. 2. The first and second decentering lenses are respectively
There is a step on the lens surface opposite to the reference lens surface.
A first and a second annular flat surface attached to the first annular surface
-Shaped flat surface and second annular flat surface with respect to the common centering axis
Are orthogonal to each other, The first lens barrel includes the first and second decentering lenses.
Protruding radially inward from its inner peripheral surface so that each supports
And a first and second lens receiving portion for The first decentering lens is the reference lens surface or the first annular surface.
Supported on the first lens receiving part on one of the flat surfaces
And is brought into contact with the first fixing means on the other surface,
Sandwiched between the first lens receiving portion and the first fixing means, The second decentering lens is the reference lens surface or the second annular surface.
Supported on the second lens receiving part on one of the flat surfaces
And by contacting the second fixing means on the other surface,
Sandwiched between the second lens receiving portion and the second fixing means, In the third decentering lens, one of the lens surfaces is
The centering axis determined as the reference lens surface is the second lens barrel.
Is arranged so as to match the axis of The third decentering lens is a lens on the side opposite to the reference lens surface.
Has a third annular flat surface that is stepped with respect to
And the third annular flat surface is the centering of the third decentering lens. On the axis
Are orthogonal to each other, The second lens barrel supports the third decentering lens.
And a third lens protruding radially inward from the inner peripheral surface thereof.
It has a receiving part, The third decentering lens is the reference lens surface or the third annular surface.
Supported on the third lens receiving part on one of the flat surfaces
By contacting the third fixing means on the other surface,
Sandwiched between the third lens receiving portion and the third fixing means
The three decentering lens holding structure according to claim 1. 3. The second lens barrel has an axis centered on the first mirror.
2. A tilt angle of a predetermined angle with respect to the axis of the cylinder.
Alternatively, the three decentering lens holding structure described in 2. The 4. Three eccentric lenses having two lens surface symmetry axis is given different from each other, respectively, a positioning method of the three eccentric lenses for positioning in the lens barrel, and any of the eccentric lens Two first and one chosen for
If the second decentering lens is directly fixed and held on the first lens barrel,
Secondly, the other third decentering lens is directly fixed and held.
The lens barrel is held in the first lens barrel, and among the curvature centers of the four lens surfaces in the first and second decentering lenses, one curvature center is arbitrarily selected from each decentering lens. A straight line is set as a common centering axis of these two decentering lenses, and these two decentering lenses are arranged so that the common centering axis is aligned with the axis of the first lens barrel. Positioning method for eccentric lens. 5. The centering axis of the third decentering lens
Inside the second lens barrel so as to match the axis of the second lens barrel.
Place and The second lens barrel is placed in the first lens barrel, and the axes of the second lens barrel and
By storing so that it can be tilted at an angle,
The centering axis of the core lens is the same as that of the first and second decentering lenses.
The contract is tilted by the predetermined angle with respect to the common centering axis.
The method for positioning three decentering lenses according to claim 4.