JP6272218B2 - Lens holding mechanism - Google Patents

Description

  The present invention relates to a lens holding mechanism that holds a lens. In particular, the present invention relates to a lens holding mechanism that is effective when it is required to satisfy high optical performance under severe temperatures and vibrations such as in an aircraft-mounted application.

  A technique for reducing stress generated in a lens by interposing an elastic body between the lens and the lens barrel is disclosed. This technology supports the lens with an elastic component that is softer than the lens and has a thickness that does not stress the lens, thereby absorbing the deformation of the lens due to changes in the ambient temperature and reducing the stress generated in the lens. (See Patent Document 1).

  In addition, by supporting the lens with a rubber layer provided in the radial gap between the lens and the lens barrel, and appropriately setting the dimensions and linear expansion coefficient of the lens, lens barrel and rubber layer, the stress generated in the lens can be reduced. A lens holding technique that theoretically makes it zero is disclosed (see Non-Patent Document 1).

JP-A-57-138606

Paul R Yonder, Jr. "Mounting optics in Optical Instruments" 2002, P66-75.

  However, in the technique of Patent Document 1, since the elastic part is a separate part from the lens and the lens barrel, there is a limit to the support with high rigidity due to the fitting gap generated between the parts. Therefore, there is a problem that it is difficult to satisfy the optical performance due to the relative displacement of the lens in a vibration environment.

  In addition, the technique of Non-Patent Document 1 does not disclose a technique for supporting the lens with high rigidity not only in the radial direction but also in the axial direction. There is a problem that it cannot be satisfied.

  The present invention supports a lens with high rigidity in multiple directions and reduces stress generated in the lens due to a difference in linear expansion. Accordingly, it is an object to reduce adverse effects on optical performance due to insufficient holding rigidity of the lens under severe temperature environments, and adverse effects on the optical performance and strength due to stress generated in the lens.

The lens holding mechanism according to the present invention is
A lens barrel having an annular convex portion protruding from the inner peripheral surface;
A lens barrel retainer inserted into the lens barrel;
A rotationally symmetric lens sandwiched between the convex portion and the lens barrel retainer;
A filler that fills a first gap formed by the side surface of the lens, the inner peripheral surface of the lens barrel, the lens barrel retainer, and the convex portion;
The first value, which is the ratio of the amount of change in volume of the first gap due to temperature change and the amount of change in volume of the filler due to temperature change, is 0.9 or more and 1.1 or less.

  According to the lens holding mechanism of the present invention, in the first first gap formed between the side surface of the lens and the inner peripheral surface of the lens barrel, the amount of change in the volume of the first gap due to temperature change and the temperature change. The first value, which is a ratio value with respect to the change in volume of the filler, is 0.9 or more and 1.1 or less. Therefore, according to the lens holding mechanism of the present invention, it is possible to hold the lens with high rigidity in multiple directions regardless of temperature changes, and to reduce the stress generated in the lens due to the difference in linear expansion coefficient. .

FIG. 3 is a cross-sectional view of the lens holding mechanism according to the first embodiment. FIG. 6 is a diagram for comparing the lens holding mechanism according to Embodiment 1 with a comparative example, where (a) is the width t1 of the comparative example gap, that is, the optimum value of the thickness of the comparative example filler, and (b) is the lens holding in the comparative example. Sectional view of the mechanism, (c) is the optimum value of the width t of the first gap, that is, the thickness of the filler 50. Sectional drawing of the lens holding mechanism 500a which concerns on Embodiment 2. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below. Moreover, in the following drawings, the relationship of the size of each component may be different from the actual one. Further, in the description of the embodiment, when directions and positions such as top, bottom, left, right, front, back, front and back are indicated, these notations are described as such for convenience of explanation. However, it does not limit the arrangement or orientation of devices, instruments, parts, and the like.

Embodiment 1 FIG.
*** Explanation of configuration ***
A lens holding mechanism 500 according to the present embodiment will be described with reference to FIG.
The right view toward FIG. 1 is a partially enlarged view of a portion surrounded by a solid line in the left view toward FIG.
The lens holding mechanism 500 includes a lens barrel 20 that holds the lens 10 and a lens barrel retainer 30 that fixes the lens 10 so as not to move.

The lens barrel 20 includes an annular convex portion 23 protruding from the inner peripheral surface 22.
The lens barrel 20 has a cylindrical shape having a peripheral wall 21. The convex portion 23 protrudes in an annular shape from the inner peripheral surface 22 of the peripheral wall 21 and contacts the rear surface of the lens 10.

The lens barrel retainer 30 is inserted into the lens barrel 20 and restrains the lens 10 in the axial direction. As shown in FIG. 1, screws are provided on the outer peripheral surface of the lens barrel retainer 30 and the inner peripheral surface of the lens barrel 20. When the lens barrel retainer 30 is screwed into the lens barrel 20, the lens barrel retainer 30 is The lens 10 is restrained. That is, the lens barrel retainer 30 is inserted and screwed in from the front surface side of the lens barrel 20 while the screw provided on the outer peripheral surface and the screw provided on the inner peripheral surface of the lens barrel 20 are screwed together. The lens barrel retainer 30 contacts the front surface of the lens 10.
The lens barrel retainer 30 and the lens barrel 20 are screwed together if the lens 10 can be restrained in the axial direction by inserting the lens barrel retainer 30 into the lens barrel 20 and fitting with the lens barrel 20. It may not be the composition to do.

The lens 10 has a rotationally symmetric shape sandwiched between the convex portion 23 and the lens barrel retainer 30. The lens 10 has, for example, a rotationally symmetric shape such as a double-sided concave lens or a convex lens, or an axially symmetric shape. The lens 10 may be substantially cylindrical.
As shown in FIG. 1, the lens 10 is inserted into the lens barrel 20 from the front side, and held between the convex portion 23 of the lens barrel 20 and the lens barrel retainer 30.

A plurality of filler injection holes 40 penetrating the peripheral wall 21 are formed in the lens barrel 20. The filler injection holes 40 are provided radially so as to penetrate the peripheral wall 21.
The filler 50 is an elastic body having a Poisson's ratio between 0.4 and 0.5.
The filler 50 is filled in a first gap 80 formed by the side surface 11 of the lens 10, the inner peripheral surface 22 of the lens barrel 20, the lens barrel retainer 30, and the convex portion 23. The filler 50 is injected into the first gap 80 through the filler injection hole 40. The radial direction of the first gap 80 is assumed to be a width t. The lens 10 is held with high rigidity as the filler 50 injected into the first gap 80 is cured.

*** Description of functions ***
The filler 50 is preferably a material having a high fluidity so that the Poisson's ratio is close to 0.5 and the first gap 80 between the lens 10 and the lens barrel 20 can be easily filled and cured. In particular, as the filler 50, a two-component curable liquid silicone rubber is suitable. When the Poisson's ratio is close to 0.5, the filler 50 whose volume change is limited by filling the first gap 80 is obtained by the volume modulus K = Young's modulus / {3 × (1-2 × Poisson's ratio)}. The holding rigidity of the lens 10 can be increased.

The width t of the first gap 80 is calculated based on the amount of change in volume of the first gap 80 due to temperature change and the amount of change in volume of the filler 50 due to temperature change. The first value F1, which is the ratio of the amount of change in the volume of the first gap 80 due to temperature change and the amount of change in the volume of the filler 50 due to temperature change, is 0.9 or more and 1.1 or less. Specifically, the width t of the first gap 80 is a first value that is a ratio value of the amount of change in the volume of the first gap 80 due to temperature change and the amount of change in the volume of the filler 50 due to temperature change. F1 is calculated to be 0.9 or more and 1.1 or less. In the present embodiment, the first value F1 is 1. That is, the amount of change in the volume of the first gap 80 due to temperature change is equal to the amount of change in the volume of the filler 50 due to temperature change.
The width t of the first gap 80 is the thickness of the filler 50. The width t of the first gap 80 may be referred to as the thickness of the filler 50.

The axial direction of the lens barrel 20 is the front-rear direction of the lens barrel 20 and is also referred to as the longitudinal direction of the lens barrel 20. Hereinafter, the axial direction of the lens barrel 20 may be simply referred to as the axial direction. In the lens barrel 20, the cross section orthogonal to the axial direction is a substantially circular ring or ring.
The radial direction of the lens barrel 20 is a direction from the center line 1 of the lens barrel 20 toward the peripheral wall 21. Alternatively, the direction is from the center of the lens 10 toward the side surface 11 of the lens 10. Hereinafter, the radial direction of the lens barrel 20 or the lens 10 may be simply referred to as a radial direction.
The circumferential direction of the lens barrel 20 is a tangential direction in a circle that is a cross section of the lens barrel 20. Alternatively, it is a tangential direction orthogonal to the axial direction on the side surface of the lens 10. Hereinafter, the circumferential direction of the lens barrel 20 may be simply referred to as a circumferential direction.
That is, the width t of the first gap 80 is the length in the radial direction between the side surface 11 of the lens 10 and the inner peripheral surface 22 of the lens barrel 20.

Next, a method for calculating the width t of the first gap 80 according to the present embodiment will be described using Equations 1 to 3.
The width t of the first gap 80 includes the linear expansion coefficient α _M of the lens barrel 20, the linear expansion coefficient α _G of the lens 10, the linear expansion coefficient α _E of the filler 50, the radius R of the lens 10, and the temperature change. It is calculated by the following formula 1 using ΔT.

  In Expression 1, the radius R of the lens 10 is R = D / 2 where D is the diameter of the lens 10. The temperature change ΔT is a temperature difference with respect to normal temperature.

A formula obtained by multiplying both sides of Formula 1 by the width W of the lens is defined as Formula 3 below.

The left side of Equation 3 represents the amount of change in the volume of the first gap 80 in the case of the temperature change ΔT.
The right side of Equation 3 represents the amount of change in the volume of the first filler gap 80 when the temperature change ΔT.
Therefore, Expression 1 and Expression 3 indicate that the amount of change in the volume of the first gap 80 in the case of the temperature change ΔT is equal to the amount of change in the volume of the filler 50 in the case of the temperature change ΔT.

  Note that the amount of change in the volume of the first gap 80 in the case of the temperature change ΔT and the amount of change in the volume of the filler 50 in the case of the temperature change ΔT need only be approximately equal, and may not be completely equal. The first value F1, which is the ratio value of the change amount of the volume of the first gap 80 in the case of the temperature change ΔT and the change amount of the volume of the filler 50 in the case of the temperature change ΔT, is 0.9 or more and 1 .1 or less is sufficient. In particular, the first value F1 is more preferably 0.95 or more and 1.05 or less, and is 1 in the present embodiment.

When ΔT × linear expansion coefficient is sufficiently smaller than 1, the width t of the first gap 80 is expressed by the following equation 2 which is an approximate expression in which a term equal to or larger than the square of ΔT × linear expansion coefficient is omitted. Is calculated. The width t of the first gap 80 is calculated by Equation 2 using the linear expansion coefficient α _M of the lens barrel, the linear expansion coefficient α _G of the lens, the linear expansion coefficient α _E of the filler, and the radius R of the lens. Is done.

  By setting the width t of the first gap 80 to satisfy Expressions 1 to 3, the amount of change in the volume of the first gap 80 when the temperature environment changes and the filler 50 filled in the first gap 80. Is substantially equal to the amount of change in volume. Therefore, even when the temperature environment changes, the radial, axial, and circumferential stresses generated in the lens 10 due to the difference in the linear expansion coefficient of each component can be minimized. Further, the lens 10 can be held with high rigidity in the radial direction, the axial direction, and the circumferential direction.

With reference to FIG. 2, the width t of the first gap 80 according to the present embodiment, that is, the optimum value of the thickness of the filler 50, and the width t1 of the comparative gap 801 in the comparative example, that is, the thickness of the comparative filler 501 are compared. The difference from the optimum value will be described.
(A) of FIG. 2 shows the optimum value of the width t1 of the comparative example gap 801 in the comparative example, that is, the thickness of the comparative example filler 501. FIG. 2B is a sectional view of the lens holding mechanism of the comparative example of FIG. (C) of FIG. 2 shows the optimum value of the width t of the first gap 80 according to the present embodiment, that is, the thickness of the filler 50, calculated using the above-described formula 2.

As shown in FIG. 2B, the width t1 of the comparative example gap 801 in the lens holding mechanism of the comparative example of FIG. 2A, that is, the thickness of the comparative filler 501 is calculated by the following equation 4. It is a thing.

Expression 5 is an expression that makes the amount of change in the radial direction of the comparative example filler 501 only substantially equal to the amount of change in the radial direction of the comparative example gap 801 only.
2 (a) and FIG. 2 (c) are compared, the width t of the first gap 80 according to the present embodiment calculated using Equation 2, that is, the thickness of the filler 50, is a comparative example. It can be seen that the width t <b> 1 of the gap 801, that is, about 1/3 of the thickness of the comparative example filler 501.

*** Explanation of effects ***
The lens holding mechanism 500 according to the present embodiment includes an optical lens, a lens barrel that holds the lens, and a filler such as rubber having a Poisson's ratio close to 0.5. While fastening with no gap in the axial direction between the lens and the lens barrel, a first gap is provided in the radial direction, and the first gap in the radial direction is filled with a filler. The lens holding mechanism sets the first gap in the radial direction to an optimum value obtained from the dimensions of each part and the linear expansion coefficients in the radial direction, axial direction, and circumferential direction of each member. With such a structure, in order to satisfy high optical performance under severe temperature and vibration environment such as on-board applications, the lens can be supported with high rigidity not only in the radial direction but also in multiple directions such as the axial direction and the circumferential direction. .

  In the lens holding mechanism according to the present embodiment, the amount of change in the volume of the first gap due to temperature change is substantially equal to the amount of change in the volume of the filler due to temperature change. Therefore, when the temperature environment changes, multidirectional stresses such as a radial direction, an axial direction, and a circumferential direction that are generated in the lens due to a difference in linear expansion coefficient of each component can be minimized.

  The width t of the first gap 80 according to the present embodiment, that is, the thickness of the filler 50 is about ３ compared with the width t1 of the comparative gap 801, that is, the thickness of the comparative example filler 501. Therefore, the filler can be thinned and can be supported with high rigidity in the axial direction. Accordingly, it is possible to increase the support rigidity while reducing the stress applied to the lens, and it is possible to reduce a necessary mounting area in an application that requires severe miniaturization such as an aircraft-mounted product.

Embodiment 2. FIG.
In the present embodiment, differences from the first embodiment will be mainly described.
In the present embodiment, the same reference numerals are given to the same components as those described in the first embodiment, and the description thereof is omitted.

*** Explanation of configuration ***
The configuration of the lens holding mechanism 500a in the present embodiment will be described with reference to FIG.
The lens holding mechanism 500a includes spacers 60a and 60b in addition to the configuration of the first embodiment.
The spacer 60 a is disposed in the second gap 82 formed between the lens 10 and the lens barrel retainer 30.
The spacer 60 b is disposed in the third gap 83 formed between the lens 10 and the convex portion 23.
Here, the width of the second gap 82 and the width of the third gap 83 are substantially equal. The width of the second gap 82 and the width of the third gap 83 are h. In addition, the spacer 60a and the spacer 60b are made of the same material and have substantially the same shape. When the spacer 60 is referred to, it means either one or both of the spacer 60a and the spacer 60b.

  In FIG. 3, the lens 10 is inserted into the lens barrel 20 from the front side, and is fixed between the lens barrel 20 and the lens barrel retainer 30 via spacers 60a and 60b, respectively.

*** Description of functions ***
The width h of the second gap 82 is calculated based on the amount of change in the width of the second gap 82 due to temperature change and the amount of change in the thickness of the spacer 60a due to temperature change. The second value F2, which is the ratio of the amount of change in the width of the second gap 82 due to temperature change and the amount of change in the thickness of the spacer 60a due to temperature change, is 0.9 or more and 1.1 or less. Specifically, the width h of the second gap 82 is a second value F2 that is a ratio value of the amount of change in the width of the second gap 82 due to temperature change and the amount of change in the thickness of the spacer 60a due to temperature change. Is calculated to be 0.9 or more and 1.1 or less.

Here, the second gap 82 and the third gap 83 are equal, and the spacer 60a and the spacer 60b are equal. Accordingly, the width h of the third gap 83 is also obtained in the same manner as the width h of the second gap. That is, the width h of the third gap is calculated based on the change amount of the width of the third gap 83 due to the temperature change and the change amount of the thickness of the spacer 60b due to the temperature change. The third value F3, which is the ratio of the amount of change in the width of the third gap 83 due to temperature change and the amount of change in the thickness of the spacer 60b due to temperature change, is 0.9 or more and 1.1 or less. Specifically, the width h of the third gap 83 is a third value F3 that is a value of the ratio between the amount of change in the width of the third gap 83 due to temperature change and the amount of change in the thickness of the spacer 60b due to temperature change. Is calculated to be 0.9 or more and 1.1 or less.
Hereinafter, the width h and the second value F2 of the second gap 82 will be described, but the same applies to the width h and the third value F3 of the third gap 83.

In the present embodiment, the second value F2 is 1. That is, the amount of change in the width of the second gap 82 is equal to the amount of change in the thickness of the spacer 60a due to temperature change.
Note that the amount of change in the width of the second gap 82 in the case of the temperature change ΔT and the amount of change in the thickness of the spacer 60a in the case of the temperature change ΔT need only be approximately equal, and may not be completely equal. A second value F2 which is a ratio value of the change amount of the width of the second gap 82 in the case of the temperature change ΔT and the change amount of the thickness of the spacer 60a in the case of the temperature change ΔT is 0.9 or more and 1. It may be 1 or less. In particular, the second value F2 is more preferably 0.95 or more and 1.05 or less, and is 1 in the present embodiment.

The width h of the second gap 82 is determined by the following equation from the linear expansion coefficient α _M of the lens barrel 20, the linear expansion coefficient α _G of the lens 10, the linear expansion coefficient α _S of the spacer 60 a, and the width W of the lens 10. Calculated by Equation 5.

  In addition, unlike the filler 50, the spacers 60a and 60b are preferably resin molded products having a linear expansion coefficient larger than that of the lens barrel 20. By interposing the spacers 60a and 60b between the metal lens barrel 20 and the lens 10, damage at the contact portion between the lens 10 and the lens barrel 20 can be prevented in a vibration environment, and the filler 50 before curing can be prevented. This is because the outflow can be prevented.

*** Explanation of effects ***
The lens holding mechanism 500a according to the present embodiment includes an optical lens, a lens barrel that holds the lens, a filler such as rubber having a Poisson's ratio close to 0.5, and a resin having a linear expansion coefficient larger than that of the lens barrel. It consists of spacers. In the axial direction between the lens and the lens barrel, spacers are sandwiched on both sides of the lens and fastened without gaps. A first gap is provided in the radial direction of the lens, a filler is filled in the first radial gap, and the first radial gap is set to an optimum value obtained from the dimensions of each part and the linear expansion coefficient of each member. Is the optimum value determined from the dimensions of each part and the linear expansion coefficient of each member. With such a configuration, when the temperature environment changes, the radial and axial stresses generated in the lens due to the difference in coefficient of linear expansion of each component can be minimized, and the contact portion between the lens and the barrel in a vibration environment In addition to preventing breakage, it is possible to prevent the filler from flowing out before curing.

  In the first and second embodiments, the case where the lens holding mechanism 500, 500a is used for holding the lens has been described. However, the lens holding mechanism 500, 500a can also be used for a holding structure for a component that is liable to be stressed and damaged due to a temperature change. It is.

  As mentioned above, although embodiment of this invention was described, you may implement combining some of these embodiment. Alternatively, any one or some of these embodiments may be partially implemented. For example, only one of those described as “parts” in the description of these embodiments may be employed, or some arbitrary combinations may be employed. In addition, this invention is not limited to these embodiment, A various change is possible as needed.

  10 lens, 11 side surface, 20 lens barrel, 21 peripheral wall, 22 inner peripheral surface, 23 convex portion, 30 lens barrel retainer, 40 filler injection hole, 50 filler, 60, 60a, 60b spacer, 80 first gap, 82 Second clearance, 83 Third clearance, 500, 500a Lens holding mechanism, 501 Comparative filler, 801 Comparative clearance, F1 first value, F2 second value, F3 third value, h, t width, l Centerline.

Claims (7)

A lens barrel having an annular convex portion protruding from the inner peripheral surface;
A lens barrel retainer inserted into the lens barrel;
A rotationally symmetric lens sandwiched between the convex portion and the lens barrel retainer;
A filler that fills a first gap formed by the side surface of the lens, the inner peripheral surface of the lens barrel, the lens barrel retainer, and the convex portion;
First value 0.9 to 1.1 der less the value of the ratio of the volume change amount of the filler according to the first clearance volume variation and the temperature change due to the temperature change is,
The width t of the first gap includes a linear expansion coefficient α _M of the lens barrel, a linear expansion coefficient α _{G of the} lens, a linear expansion coefficient α _{E of the} filler , a radius R of the lens, and the temperature. lens holding mechanism that will be calculated by the equation 1 by using the ΔT is the change.

  A lens barrel having an annular convex portion protruding from the inner peripheral surface;
  A lens barrel retainer inserted into the lens barrel;
  A rotationally symmetric lens sandwiched between the convex portion and the lens barrel retainer;
  A filler filled in a first gap formed by a side surface of the lens, an inner peripheral surface of the lens barrel, the lens barrel retainer, and the convex portion;
With
  A first value which is a value of a ratio between a change amount of the volume of the first gap due to a temperature change and a change amount of the volume of the filler due to the temperature change is 0.9 or more and 1.1 or less;
  The width t of the first gap is the linear expansion coefficient α of the lens barrel. _M And the linear expansion coefficient α of the lens _G And the linear expansion coefficient α of the filler _E And a lens holding mechanism calculated by Equation 2 using the radius R of the lens.

The first value is a lens holding mechanism according to claim 1 or 2 is 1. A spacer disposed in each of a second gap formed between the lens and the lens barrel retainer and a third gap formed between the lens and the convex portion;
The width of the second gap is equal to the width of the third gap,
2. A second value that is a ratio value of a change amount of the width of the second gap due to the temperature change and a change amount of the thickness of the spacer due to the temperature change is 0.9 or more and 1.1 or less. The lens holding mechanism according to any one of 1 to 3 . The lens holding mechanism according to claim 4 , wherein the width of the second gap is calculated based on a change amount of the width of the second gap due to the temperature change and a change amount of the thickness of the spacer due to the temperature change. . The width h of the second gap is given by Equation 5 from the linear expansion coefficient α _M of the lens barrel, the linear expansion coefficient α _{G of the} lens, the linear expansion coefficient α _{S of the} spacer, and the width W of the lens. The lens holding mechanism according to claim 5 , wherein the lens holding mechanism is calculated.

The lens holding mechanism according to any one of claims 1 to 6 , wherein the filler is an elastic body having a Poisson's ratio of 0.4 or more and 0.5 or less.

Images