Lens module

Abstract

To provide a lens module capable of achieving size reduction, improvement in optical performance and reliability, and cost reduction.SOLUTION: The lens module includes: lenses L1 and L2; a lens holder 21 for accommodating the lens L2; a barrel 11 in which the lens L1 is accommodated at one end and the lens holder 21 is inserted from the other end, the lens holder 21 accommodating the lens L2; an adjustment bolt 31 for moving the lens holder 21 in the direction of an optical axis O; and a disc spring 41 having an annular shape and serving as an elastic member interposed between the lenses L1 and L2 in the barrel 11 to apply a load to the lenses L1 and L2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a lens module. [Background technology]

[0002] Lens modules that combine multiple lenses or that combine a lens with an image sensor or the like are known to have a mechanism for adjusting the position of the lens in the optical axis direction to ensure optical performance. Because the optical performance of a lens module can be degraded by field curvature caused by the distance between the lenses or by defocus caused by the distance between the lens and the image sensor, various mechanisms have been proposed for measuring optical performance and adjusting the position of the lens in the optical axis direction to an optimal position.

[0003] In Patent Document 1, a lens holding member that holds a lens is held against a fixed lens barrel by an elastic disk, and the lens holding member is pressed in the optical axis direction by a pressing structure that has a cam member, cam follower, pin member, and operation ring. The position in the optical axis direction is adjusted by the pressing structure, and the lens holding member is biased by the elastic force of the elastic disk, thereby stabilizing the position and posture of the lens holding member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-43471 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in Patent Document 1, because the lens is housed and fixed inside the lens holding member, it is necessary to press the lens holding member with a pressing structure or to fix the lens to the lens holding member with an adhesive. If a pressing member is used, the lens movement mechanism and therefore the lens module will become larger due to the installation space required. If an adhesive is used, there is a concern that optical performance and reliability will be reduced due to outgassing. Furthermore, in either case, the increased number of parts will lead to higher costs.

[0006] The present disclosure has been made in view of the above, and aims to provide a lens module that can achieve miniaturization, improved optical performance and reliability, and reduced costs. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the objectives, the lens module of the present disclosure comprises a first lens and a second lens, a lens holder that houses the first lens, a lens barrel that houses the second lens at one end and into which the lens holder housing the first lens is inserted from the other end, a moving mechanism that moves the lens holder in the optical axis direction, and an elastic ring that is a circular-ring-shaped elastic body that is interposed between the first lens and the second lens in the lens barrel and applies a load to at least the first lens toward the other end. [Effects of the Invention]

[0008] The lens module of the present disclosure has the advantages of being able to reduce the size of the lens module, improve optical performance and reliability, and reduce costs. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing a configuration of a lens module according to a first embodiment; [Figure 2] FIG. 1 is a bottom view showing a configuration of a lens module according to a first embodiment; [Figure 3] FIG. 1 is an exploded cross-sectional view showing a configuration of a lens module according to a first embodiment. [Figure 4] FIG. 1 is a perspective view showing a configuration of a disc spring of a lens module according to a first embodiment; [Figure 5] FIG. 1 is a top view showing a configuration of a disc spring of a lens module according to a first embodiment; [Figure 6] FIG. 1 is a cross-sectional view showing a configuration of a disc spring of a lens module according to a first embodiment; [Figure 7] FIG. 1 is a schematic diagram illustrating deformation of a disc spring of a lens module according to a first embodiment when a load is applied thereto; [Figure 8] FIG. 1 is a diagram showing an example of specifications in a design example of a disc spring of a lens module according to a first embodiment; [Figure 9] FIG. 10 is a diagram showing the relationship between the deformation amount and the load of the disc spring of the lens module according to the first embodiment. [Figure 10] FIG. 10 is a cross-sectional view showing the configuration of a lens module according to a second embodiment. [Figure 11] FIG. 10 is a bottom view showing the configuration of the lens module according to the second embodiment. [Figure 12] FIG. 10 is an exploded cross-sectional view showing the configuration of a lens module according to a second embodiment. [Figure 13] FIG. 10 is a perspective view showing the configuration of a flat circular plate of a lens module according to a second embodiment; [Figure 14] FIG. 10 is a top view showing the configuration of the flat circular plate of the lens module according to the second embodiment; [Figure 15] FIG. 10 is a cross-sectional view showing the configuration of a flat circular plate of a lens module according to a second embodiment; [Figure 16] FIG. 10 is a schematic diagram showing deformation of a flat circular plate of a lens module according to a second embodiment when a load is applied; [Figure 17] FIG. 10 is a diagram showing an example of specifications in a design example of a flat circular plate of a lens module according to a second embodiment; [Figure 18] FIG. 10 is a diagram showing the relationship between the deformation amount and the load of the flat circular plate of the lens module according to the second embodiment. [Figure 19] FIG. 10 is a cross-sectional view showing a configuration of a modified example of the lens module according to the second embodiment. [Figure 20] FIG. 10 is a bottom view showing a configuration of a modified example of the lens module according to the second embodiment. [Figure 21] FIG. 10 is an exploded cross-sectional view showing a configuration of a modified example of the lens module according to the second embodiment. [Figure 22] FIG. 10 is a cross-sectional view showing the configuration of a lens module according to a third embodiment. [Figure 23] FIG. 10 is a bottom view showing the configuration of the lens module according to the third embodiment. [Figure 24] FIG. 10 is an exploded cross-sectional view showing the configuration of a lens module according to a third embodiment. [Figure 25] FIG. 11 is a perspective view showing a configuration of an O-ring of the lens module according to the third embodiment; [Figure 26] FIG. 10 is a top view showing a configuration of an O-ring of the lens module according to the third embodiment; [Figure 27] FIG. 10 is a cross-sectional view showing a configuration of an O-ring of the lens module according to the third embodiment. [Figure 28] FIG. 10 is a schematic diagram illustrating deformation of an O-ring of a lens module according to a third embodiment when a load is applied thereto; [Figure 29] FIG. 10 is a diagram showing an example of specifications in a design example of an O-ring of a lens module according to a third embodiment. [Figure 30] FIG. 10 is a diagram showing the relationship between the deformation amount of the O-ring and the load of the lens module according to the third embodiment. [Figure 31] FIG. 10 is a top view showing the configuration of a lens module according to a fourth embodiment. [Figure 32] FIG. 10 is a cross-sectional view showing the configuration of a lens module according to a fourth embodiment. [Figure 33] FIG. 10 is a bottom view showing the configuration of the lens module according to the fourth embodiment. [Figure 34] FIG. 10 is an exploded cross-sectional view showing the configuration of a lens module according to a fourth embodiment. [Figure 35] 10A to 10C are cross-sectional views showing a procedure for removing a micrometer head in the lens module according to the fourth embodiment. [Figure 36] FIG. 10 is a cross-sectional view showing the configuration of a lens module according to a fifth embodiment. [Figure 37] FIG. 13 is a bottom view showing the configuration of the lens module according to the fifth embodiment. [Figure 38] FIG. 10 is an exploded cross-sectional view showing the configuration of a lens module according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] A lens module according to an embodiment will be described in detail below with reference to the drawings.

[0011] Embodiment 1 FIG. 1 is a cross-sectional view showing the configuration of the lens module 1 according to the first embodiment. FIG. 2 is a bottom view showing the configuration of the lens module 1 according to the first embodiment. FIG. 1 is a cross-sectional view taken along line II in FIG. 2. FIG. 3 is an exploded cross-sectional view showing the configuration of the lens module 1 according to the first embodiment. FIG. 4 is a perspective view showing the configuration of a disc spring 41 of the lens module 1 according to the first embodiment. FIG. 5 is a top view showing the configuration of the disc spring 41 of the lens module 1 according to the first embodiment. FIG. 6 is a cross-sectional view showing the configuration of the disc spring 41 of the lens module 1 according to the first embodiment. For ease of explanation, coordinate axes X, Y, and Z are added to FIGS. 1 to 3. The Z-axis direction corresponds to the direction of the optical axis O of the lenses L1 and L2. The X-axis direction and the Y-axis direction are perpendicular to the Z-axis direction.

[0012] The lens module 1 includes a lens assembly L consisting of two lenses L1 and L2, a lens barrel 11, a lens holder 21, an adjustment bolt 31 as a movement mechanism, a disc spring 41 as an elastic ring that is an annular elastic body, and protective washers 51 and 52. The lens L1 corresponds to the second lens, and the lens L2 corresponds to the first lens. The lens L1 is housed at one end of the lens barrel 11, and the lens L2 is housed at the other end.

[0013] The lens barrel 11 has a two-stage cylindrical shape with a small-diameter cylindrical portion 11a and a large-diameter cylindrical portion 11b, and accommodates the entire lens assembly L. The lens L1 is accommodated on the inner peripheral surface of the small-diameter cylindrical portion 11a, which has a lens opening 11d. The lens L2 is accommodated in the large-diameter cylindrical portion 11b via a lens holder 21. The diameter of the lens opening 11d is smaller than the diameter of the lens L1. The bottom surface of the large-diameter cylindrical portion 11b is provided with a plurality of screw holes 11c into which a plurality of adjustment bolts 31 are inserted.

[0014] Lens holder 21 includes an annular portion 21b having lens opening 21a, and a cylindrical portion 21c protruding from annular portion 21b in the direction of optical axis O. Lens L2 is housed on the inner circumferential surface of cylindrical portion 21c of lens holder 21. Cylindrical portion 21c of lens holder 21 is inserted into large-diameter cylindrical portion 11b of lens barrel 11. Annular portion 21b is provided with a plurality of screw holes 21d into which a plurality of adjustment bolts 31 are inserted.

[0015] Lens L1 is stored in lens barrel 11, protective washer 51, disc spring 41, and protective washer 52 are stored in lens barrel 11, lens holder 21 storing lens L2 is inserted into lens barrel 11, and adjustment bolt 31 is inserted into screw holes 21d and 11c and turned, whereby adjustment bolt 31 is tightened and lens holder 21 can be moved in the direction of optical axis O relative to lens barrel 11.

[0016] The disc spring 41 is a spring shaped like a circular disc. The disc spring 41 is arranged at the step portion that is the boundary between the small-diameter cylindrical portion 11a and the large-diameter cylindrical portion 11b of the lens barrel 11. The disc spring 41 applies a load to the lens L2 in the direction of insertion into the lens holder 21 (+Z direction). The disc spring 41 applies a load to the lens L1 in the direction of insertion into the lens barrel 11 (-Z direction). The protective washer 51 is interposed between the disc spring 41 and the lens L1, and is arranged on the small-diameter cylindrical portion 11a of the lens barrel 11. The protective washer 52 is interposed between the disc spring 41 and the lens L2, and is arranged on the large-diameter cylindrical portion 11b of the lens barrel 11.

[0017] Lens L2 is a movable lens, and lens L1 is a stationary lens. Lens L2 presses and deforms disc spring 41, causing disc spring 41 to apply a load to lens L2 and, at the same time, to lens L1 in the direction of insertion into lens barrel 11. The threaded portion of adjustment bolt 31 engages with threaded hole 11c of lens barrel 11, and the seating surface of adjustment bolt 31 abuts against annular portion 21b of lens holder 21, so that lens holder 21 can be moved in the direction of optical axis O relative to lens barrel 11 by tightening or loosening adjustment bolt 31.

[0018] The effect of the disc spring 41 will now be described. The optical performance of the lens module 1 can be ensured by using the lens holder 21 to move the lens L2 in the direction of the optical axis O and adjust it to an optimal position. The optimal position of the lens in the direction of the optical axis O is simply referred to as the optimal lens position. The lens holder 21 is pressed in the -Z direction by the adjustment bolt 31 to position it, but positional deviation occurs due to play in the threaded portion of the adjustment bolt 31 and floating from the seating surface. In the first embodiment, the disc spring 41 presses and urges the lens holder 21 in the +Z direction, thereby preventing such positional deviation.

[0019] Although lens L2 is fitted into lens holder 21, there is a concern that vibration or the like may cause lens L2 to float in the -Z direction from the receiving surface of lens holder 21. In embodiment 1, disc spring 41 applies a load to lens L2 in the +Z direction, thereby preventing such floating and fixing lens L2 in lens holder 21. In other words, fixing lens L2 with a separate pressing member or adhesive is no longer necessary, making it possible to reduce the size of lens module 1, improve optical performance and reliability, and reduce costs.

[0020] Similarly, by having disc spring 41 apply a load in the -Z direction to lens L1, it is possible to prevent lens L1 from falling out of lens barrel 11 and fix lens L1 within lens barrel 11. This eliminates the need to fix lens L1 with a separate pressing member or adhesive, and enables further miniaturization and cost reduction of lens module 1.

[0021] Furthermore, the disc spring 41 has the advantage of being able to suppress fluctuations in load when the deformation amount deviates from the design value. This advantage will be explained below. The optimal value of the deformation amount δ of the disc spring 41 when the lens L2 is in the optimal position will be referred to as the optimal deformation amount δopt. Furthermore, the optimal deformation amount δopt of the disc spring 41 when the dimensions of each component such as the lens barrel 11, the refractive index of the lens, the surface shape, and so on are as designed will be referred to as the designed deformation amount δdsg. Due to factors such as the dimensional tolerances of the components, the optimal deformation amount δopt of the disc spring 41 fluctuates from the designed deformation amount δdsg. When the deformation amount δ of the disc spring 41 fluctuates from the designed deformation amount δdsg, the load P of the disc spring 41, i.e., the repulsive force that the disc spring 41 exerts on the lenses L1 and L2, fluctuates from the design load Pdsg, which is the design value of the load.

[0022] If the load P is too small, the aforementioned positioning bias and lens fixing effects will be insufficient. On the other hand, if the load P is too large, strong stress and distortion will be applied to the lens, degrading the optical characteristics of the lens. Therefore, it is desirable that the fluctuation of the load P relative to the fluctuation of the deformation amount δ be small.

[0023] 7 is a schematic diagram showing deformation of the disc spring 41 of the lens module 1 according to the first embodiment when a load is applied. As shown in FIG. 7, when a load P is applied to the disc spring 41, the disc spring 41 elastically deforms from the pre-deformation state indicated by the dashed line to the post-deformation state indicated by the solid line. The specifications of the disc spring 41 include the outer diameter Do, inner diameter Di, plate thickness t, and depth h shown in FIG. 6, as well as the Young's modulus E of the material and the Poisson's ratio ν of the material. The relationship between the deformation amount δ of the disc spring 41 and the load P is approximated by the following Almen-Laszlo equation, Equation (1).

[0024]

number

[0025] By appropriately designing the specifications of the disc spring 41 based on this formula (1) and under various design constraints of the lens module 1, it is possible to reduce the fluctuation of the load P relative to the fluctuation of the deformation amount δ.

[0026] Fig. 8 is a diagram showing an example of specifications in a design example of the disc spring 41 of the lens module 1 according to the first embodiment. In the design example shown in Fig. 8, the Young's modulus E of the material is set to 193 GPa, the Poisson's ratio ν of the material is set to 0.3, the outer diameter Do is set to 106 mm, the inner diameter Di is set to 93 mm, the plate thickness t is set to 0.5 mm, the depth h is set to 0.8 mm, and the design deformation amount δdsg is set to 0.5 mm.

[0027] FIG. 9 is a diagram showing the relationship between the deformation δ and the load P of the disc spring 41 of the lens module 1 according to the first embodiment. FIG. 9 shows the relationship between the deformation δ and the load P of a design example having the specifications shown in FIG. 8. The horizontal axis shows the deformation δ, and the vertical axis shows the load P. For comparison, the broken line in FIG. 9 shows the relationship between the deformation δ and the load P of a linear spring that follows Hooke's law. The solid line shows the relationship between the deformation δ and the load P of the design example of the disc spring 41. Unlike a linear spring, the load P of the disc spring 41 is expressed by a cubic equation of the deformation δ and is asymmetric with respect to the origin. Therefore, as in this design example, it is possible to design the disc spring 41 so that the variation in the load P relative to the variation in the deformation δ is small, thereby suppressing the effects of tolerances.

[0028] The effect of the protective washers 51 and 52 will now be described. When assembling the lens module 1 or moving the lens holder 21 in the direction of the optical axis O to adjust it to an optimal position, the disc spring 41 slides between the components that it abuts above and below in response to its deformation. If the protective washers 51 and 52 were not present and the disc spring 41 abutted against the lenses L1 and L2, there is a concern that the lenses L1 and L2 would be scratched by the sliding of the disc spring 41. In contrast, by interposing the protective washers 52 and 51 between the disc spring 41 and the lens L2 and between the disc spring 41 and the lens L1, respectively, it is possible to prevent the lenses L1 and L2 from being scratched by the sliding of the disc spring 41.

[0029] The following describes the effect of adjustment bolt 31. Adjustment bolt 31 serves both to assemble and fix lens holder 21 to lens barrel 11 and to move lens holder 21 in the optical axis direction, thereby reducing the number of parts.

[0030] Although a method or mechanism for regulating or adjusting misalignment in a direction perpendicular to the optical axis is not shown, lens module 1 may include such a mechanism. Examples of methods for regulating misalignment include designing the fit clearance between lens barrel 11 and lens holder 21 to be sufficiently narrow, or using a ball bearing or ball roller screw. Examples of methods for adjusting misalignment include using a micrometer head to position lens holder 21 in a direction perpendicular to optical axis O.

[0031] As described above, according to embodiment 1, the disc spring 41 as an elastic ring biases the adjustment bolt 31 as a moving mechanism and fixes the lens within the lens holder 21, eliminating the need for a separate retaining member or fixation with adhesive, thereby enabling the lens module to be made smaller, with improved optical performance and reliability, and at a reduced cost.

[0032] Embodiment 2 FIG. 10 is a cross-sectional view showing the configuration of the lens module 2 according to the second embodiment. FIG. 11 is a bottom view showing the configuration of the lens module 2 according to the second embodiment. FIG. 10 is a cross-sectional view taken along line XX in FIG. 11. FIG. 12 is an exploded cross-sectional view showing the configuration of the lens module 2 according to the second embodiment. FIG. 13 is a perspective view showing the configuration of the flat circular ring 42 of the lens module 2 according to the second embodiment. FIG. 14 is a top view showing the configuration of the flat circular ring 42 of the lens module 2 according to the second embodiment. FIG. 15 is a cross-sectional view showing the configuration of the flat circular ring 42 of the lens module 2 according to the second embodiment.

[0033] In the second embodiment, the disc spring 41 of the first embodiment is replaced with a flat ring 42. This is the main difference between the second embodiment and the first embodiment. In the second embodiment, components having the same functions as those in the first embodiment are given the same reference numerals, and redundant explanations will be omitted.

[0034] The lens module 2 includes a lens assembly L consisting of two lenses L1 and L2, a lens barrel 12, a lens holder 21, an adjustment bolt 31, a flat ring 42 serving as an elastic ring, and a cap screw 62. The cap screw is a ring-shaped member with a male thread formed on its outer periphery.

[0035] Lens barrel 12 has a two-stage cylindrical shape with a small-diameter cylindrical portion 12a and a large-diameter cylindrical portion 12b, and entirely houses lens assembly L. Lens L1 is housed on the inner circumferential surface of small-diameter cylindrical portion 12a, which has lens opening 12d. Lens L2 is housed in large-diameter cylindrical portion 12b via lens holder 21. A plurality of threaded holes 12c are provided in the bottom surface of large-diameter cylindrical portion 12b, into which a plurality of adjustment bolts 31 are inserted. An internal thread is formed in the inner circumferential portion of lens barrel 12, into which cap screw 62 is inserted.

[0036] Lens holder 21 includes an annular portion 21b having a lens opening 21a, and a cylindrical portion 21c protruding from annular portion 21b in the direction of optical axis O. Lens L2 is housed on the inner circumferential surface of cylindrical portion 21c of lens holder 21. Cylindrical portion 21c of lens holder 21 is inserted into large-diameter cylindrical portion 12b of lens barrel 12. Annular portion 21b is provided with a plurality of screw holes 21d into which a plurality of adjustment bolts 31 are inserted.

[0037] Lens L1 is stored in lens barrel 12, and lens L1 is fixed to lens barrel 12 by rotating cap screw 62. Thereafter, flat ring 42 and lens holder 21 storing lens L2 are inserted into lens barrel 12, and adjustment bolt 31 is inserted into threaded holes 21d and 12c and rotated to tighten adjustment bolt 31, and lens holder 21 can be moved in the direction of optical axis O relative to lens barrel 12.

[0038] The flat ring 42 is an annular elastic body. The flat ring 42 is disposed at a step portion that is the boundary between the small-diameter cylindrical portion 12a and the large-diameter cylindrical portion 12b of the lens barrel 12. The flat ring 42 applies a load to the lens L2 in the direction of insertion into the lens holder 21 (the +Z direction).

[0039] Lens L2 presses against flat ring 42, deforming flat ring 42 into a disc spring shape, causing flat ring 42 to apply a load to lens L2. Flat ring 42 does not apply a load to lens L1, so lens L1 inserted in lens barrel 12 is fixed to lens barrel 12 with cap screws 62. By using flat ring 42 as the elastic ring, the function of applying a load to lens L2 can be achieved more cheaply than with disc springs 41.

[0040] 16 is a schematic diagram showing deformation of the flat ring 42 of the lens module 2 according to the second embodiment when a load is applied. As shown in FIG. 16, when a load P is applied to the flat ring 42, the flat ring 42 elastically deforms from the pre-deformation state indicated by the dashed line to the post-deformation state indicated by the solid line. Specifications of the flat ring 42 include the outer diameter Do, inner diameter Di, and plate thickness t shown in FIG. 15, as well as the Young's modulus E and Poisson's ratio ν of the material. The relationship between the deformation amount δ of the flat ring 42 and the load P is approximated as equation (2) in which h=0 in equation (1).

[0041]

number

[0042] Based on this formula (2), the specifications of the flat circular plate 42 are appropriately designed under various design constraints of the lens module 2.

[0043] Fig. 17 is a diagram showing an example of specifications in a design example of the flat annular ring 42 of the lens module 2 according to the second embodiment. In the design example shown in Fig. 17, the Young's modulus E of the material is set to 193 GPa, the Poisson's ratio ν of the material is set to 0.3, the outer diameter Do is set to 106 mm, the inner diameter Di is set to 93 mm, the plate thickness t is set to 0.5 mm, and the design deformation amount δdsg is set to 0.5 mm.

[0044] Fig. 18 is a diagram showing the relationship between the deformation amount δ and the load P of the flat circular ring 42 of the lens module 2 according to the second embodiment. Fig. 18 shows the relationship between the deformation amount δ and the load P for a design example having the specifications shown in Fig. 17. The horizontal axis shows the deformation amount δ, and the vertical axis shows the load P. In the method of the second embodiment in which the flat circular ring 42 is deformed into the shape of a disc spring, the load P increases at an accelerated rate with respect to the deformation amount δ, and therefore, as shown in Fig. 18, this method is disadvantageous compared to the disc spring 41 in the first embodiment in terms of suppressing fluctuations in the load P in response to fluctuations in the deformation amount δ.

[0045] Fig. 19 is a cross-sectional view showing the configuration of a modified example of the lens module 2a according to the second embodiment. Fig. 20 is a bottom view showing the configuration of a modified example of the lens module 2a according to the second embodiment. Fig. 19 is a cross-sectional view taken along line XIX-XIX in Fig. 20. Fig. 21 is an exploded cross-sectional view showing the configuration of a modified example of the lens module 2a according to the second embodiment.

[0046] Lens module 2a includes a lens assembly L consisting of two lenses L1 and L2, a lens barrel 12, a lens holder 21, an adjustment bolt 31, a flat ring 42 serving as an elastic ring, and protective washers 51 and 52. In the modified example shown in Figures 19 to 21, cap screw 62 is eliminated, and protective washers 51 and 52 are provided on both sides of flat ring 42. The rest of the configuration of lens module 2a is the same as that of lens module 2, and redundant explanations will be omitted.

[0047] Lens L1 is stored in lens barrel 12, protective washer 51, flat ring 42, and protective washer 52 are stored in lens barrel 12, lens holder 21 storing lens L2 is inserted into lens barrel 12, and adjustment bolt 31 is inserted into screw holes 21d and 11c and turned, whereby adjustment bolt 31 is tightened and lens holder 21 can be moved in the direction of optical axis O relative to lens barrel 12.

[0048] The flat ring 42 applies a load to the lens L2 in the direction of insertion into the lens holder 21 (+Z direction) via the protective washer 52, and similarly applies a load to the lens L1 in the direction of insertion into the lens barrel 12 (-Z direction) via the protective washer 51.

[0049] As described above, according to the second embodiment, the flat ring 42 as an elastic ring biases the adjustment bolt 31 as a moving mechanism and fixes the lens in the lens holder 21, eliminating the need for a separate pressing member or fixation with an adhesive, thereby realizing miniaturization of the lens module, improvement of optical performance and reliability, and cost reduction.

[0050] Embodiment 3 FIG. 22 is a cross-sectional view showing the configuration of lens module 3 according to the third embodiment. FIG. 23 is a bottom view showing the configuration of lens module 3 according to the third embodiment. FIG. 22 is a cross-sectional view taken along line XXII-XXII in FIG. 23. FIG. 24 is an exploded cross-sectional view showing the configuration of lens module 3 according to the third embodiment. FIG. 25 is a perspective view showing the configuration of O-ring 43 of lens module 3 according to the third embodiment. FIG. 26 is a top view showing the configuration of O-ring 43 of lens module 3 according to the third embodiment. FIG. 27 is a cross-sectional view showing the configuration of O-ring 43 of lens module 3 according to the third embodiment.

[0051] In the third embodiment, the disc spring 41 of the first embodiment is replaced with an O-ring 43. This is the main difference between the third embodiment and the first embodiment. In the third embodiment, the components having the same functions as those in the first embodiment are given the same reference numerals, and redundant explanations will be omitted.

[0052] The lens module 3 includes a lens assembly L consisting of two lenses L1 and L2, a lens barrel 11, a lens holder 21, an adjustment bolt 31, and an O-ring 43 as an elastic ring.

[0053] Lens barrel 11 has a two-stage cylindrical shape with a small-diameter cylindrical portion 11a and a large-diameter cylindrical portion 11b, and entirely houses lens assembly L. Lens L1 is housed on the inner circumferential surface of small-diameter cylindrical portion 11a, which has lens opening 11d. Lens L2 is housed in large-diameter cylindrical portion 11b via lens holder 21. A plurality of threaded holes 11c are provided in the bottom surface of large-diameter cylindrical portion 11b, into which a plurality of adjustment bolts 31 are inserted.

[0054] Lens holder 21 includes an annular portion 21b having a lens opening 21a, and a cylindrical portion 21c protruding from annular portion 21b in the direction of optical axis O. Lens L2 is housed on the inner circumferential surface of cylindrical portion 21c of lens holder 21. Cylindrical portion 21c of lens holder 21 is inserted into large-diameter cylindrical portion 12b of lens barrel 11. Annular portion 21b is provided with a plurality of screw holes 21d into which a plurality of adjustment bolts 31 are inserted.

[0055] Lens L1 is stored in lens barrel 11, and O-ring 43 is housed in lens barrel 11. Thereafter, lens holder 21 storing lens L2 is inserted into lens barrel 11, and adjustment bolt 31 is inserted into threaded holes 21d and 11c and turned, thereby tightening adjustment bolt 31 and moving lens holder 21 in the direction of optical axis O relative to lens barrel 11.

[0056] The O-ring 43 is an annular elastic body. The O-ring 43 is placed at the step portion that is the boundary between the small-diameter cylindrical portion 11a and the large-diameter cylindrical portion 11b of the lens barrel 11. When the lens L2 presses and deforms the O-ring 43, the O-ring 43 applies a load to the lens L2 in the direction of insertion into the lens holder 21 (+Z direction). At this time, the O-ring 43 also applies a load to the lens L1 in the direction of insertion into the lens barrel 11 (-Z direction). The O-ring 43 is made of a resin such as rubber, and there is no risk of scratches on the lenses L1 and L2, so no protective washers are required between the O-ring 43 and the lenses L1 and L2.

[0057] By using the O-ring 43 as the elastic ring, the function of applying a load to the lenses L1 and L2 can be achieved more inexpensively than by using the disc spring 41 and the flat ring 42. In addition, protective washers for preventing scratches can be eliminated, thereby reducing costs.

[0058] 28 is a schematic diagram showing deformation of O-ring 43 of lens module 3 according to the third embodiment when a load is applied. As shown in FIG. 28, when a load P is applied to O-ring 43, O-ring 43 elastically deforms from the pre-deformation state indicated by the dashed line to the post-deformation state indicated by the solid line. The specifications of O-ring 43 include the average diameter D and wire diameter φ shown in FIG. 27, and the JIS durometer hardness A type H of the material. The relationship between the deformation amount δ of O-ring 43 and the load P is empirically approximated by the following equation (3):

[0059]

number

[0060] Based on this formula (3), the specifications of the O-ring 43 are appropriately designed under various design constraints of the lens module 3.

[0061] Fig. 29 is a diagram showing an example of specifications in a design example of O-ring 43 of lens module 3 according to embodiment 3. In the design example shown in Fig. 29, the JIS durometer hardness type A H of the material is set to 50, the average diameter D is set to 20 mm, the wire diameter φ is set to 4 mm, and the design deformation amount Δdsg is set to 0.5 mm.

[0062] Fig. 30 is a diagram showing the relationship between the deformation amount δ and the load P of the O-ring 43 of the lens module 3 according to the third embodiment. Fig. 30 shows the relationship between the deformation amount δ and the load P for a design example having the specifications shown in Fig. 29. The horizontal axis shows the deformation amount δ, and the vertical axis shows the load P. With the O-ring 43, the load P increases at an accelerated rate with respect to the deformation amount δ, and therefore, compared to the disc spring 41 according to the first embodiment, the O-ring 43 is at a disadvantage in terms of suppressing fluctuations in the load P relative to fluctuations in the deformation amount δ.

[0063] As described above, according to the third embodiment, O-ring 43 as an elastic ring is used to bias adjustment bolt 31 as a moving mechanism and to fix the lens within lens holder 21, eliminating the need for a separate retaining member or fixation with adhesive, thereby enabling the lens module to be made smaller, with improved optical performance and reliability, and at a reduced cost.

[0064] Embodiment 4 FIG. 31 is a top view showing the configuration of a lens module 4 according to the fourth embodiment. FIG. 32 is a cross-sectional view showing the configuration of a lens module 4 according to the fourth embodiment. FIG. 32 is a cross-sectional view taken along line XXXII-XXXII in FIG. 31. FIG. 33 is a bottom view showing the configuration of a lens module 4 according to the fourth embodiment. FIG. 34 is an exploded cross-sectional view showing the configuration of a lens module 4 according to the fourth embodiment. FIGS. 32, 33, and 34 show the lens module 4 in a state at the time of shipment. For ease of explanation, a micrometer head 34 has been added to FIG. 34.

[0065] The lens module 4 includes a lens assembly L consisting of two lenses L1 and L2, a lens barrel 14, a lens holder 24, a micrometer head holder 35, a disc spring 41 as an elastic ring, protective washers 51 and 52, a fixing bolt 18, and a fixing bolt 19. The micrometer head 34 and the micrometer head holder 35 form a movement mechanism.

[0066] Lens barrel 14 has a three-stage cylindrical shape with small-diameter cylindrical portion 14a, medium-diameter cylindrical portion 14b, and large-diameter cylindrical portion 14c, and accommodates entire lens assembly L. Lens L1 is accommodated on the inner circumferential surface of small-diameter cylindrical portion 14a, which has lens opening 14d. Lens L2 is accommodated in large-diameter cylindrical portion 14c via lens holder 24. Disc spring 41 is accommodated in medium-diameter cylindrical portion 14b. A plurality of screw holes 14e are provided in the bottom surface of large-diameter cylindrical portion 14c, into which a plurality of fixing bolts 19 are inserted. Furthermore, a plurality of screw holes 14f are provided in the top surface of medium-diameter cylindrical portion 14b, into which a plurality of temporary fixing bolts 17 are inserted to temporarily fix the position of lens holder 24.

[0067] Lens holder 24 includes an annular portion 24b having a lens opening 24a, and a cylindrical portion 24c protruding from annular portion 24b in the direction of optical axis O. Lens L2 is housed on the inner circumferential surface of cylindrical portion 24c of lens holder 24. Cylindrical portion 24c of lens holder 24 is inserted into large-diameter cylindrical portion 14c of lens barrel 14.

[0068] Similar to the first embodiment, the disc spring 41 applies a load to the lens L2 in the direction of insertion into the lens holder 24 (+Z direction). The disc spring 41 applies a load to the lens L1 in the direction of insertion into the lens barrel 14 (-Z direction). The protective washer 51 is interposed between the disc spring 41 and the lens L1, and is disposed on the small-diameter cylindrical portion 14a of the lens barrel 14. The protective washer 52 is interposed between the disc spring 41 and the lens L2, and is disposed on the medium-diameter cylindrical portion 14b of the lens barrel 14.

[0069] The micrometer head holder 35 is formed in a circular ring shape having a lens opening 35d. The micrometer head holder 35 is provided with a plurality of screw holes 35b into which a plurality of fixing bolts 19 are inserted, a plurality of holder holes 35a into which the tips of a plurality of micrometer heads 34 are inserted, and a plurality of screw holes 35c into which fixing bolts 18 for fixing the lens holder 24 are inserted.

[0070] Micrometer head 34 is an instrument that uses a screw mechanism to precisely measure length, and by rotating thimble 34a, lens holder 24, which is in contact with the measurement surface at the tip, can be moved in the direction of optical axis O. When lens holder 24 is moved in the direction of optical axis O, multiple micrometer heads 34 are inserted into and held in holder holes 35a of micrometer head holder 35.

[0071] Lens L1 is stored in lens barrel 14, protective washer 51, disc spring 41, and protective washer 52 are also stored in lens barrel 14, lens holder 24 storing lens L2 is inserted into lens barrel 14, and micrometer head holder 35 is fixed to lens barrel 14 with fixing bolt 19. Micrometer head 34 is set in holder hole 35a of micrometer head holder 35, and lens holder 24 can be moved in the direction of optical axis O by rotating thimble 34a of micrometer head 34, enabling highly accurate adjustment of the lens position.

[0072] In the case of the adjustment bolt 31 shown in the first embodiment, even the fine M2 thread has a pitch of 0.25 mm, making it difficult to manually tighten or loosen it to achieve high-precision position adjustment of 10 μm or less. On the other hand, some micrometer heads 34 have a scale formed in 1 μm increments, making it possible to perform high-precision position adjustment.

[0073] On the other hand, micrometer head 34 is generally more expensive and larger than adjustment bolt 31, which increases the cost and size of lens module 4. Therefore, in the fourth embodiment, after adjusting the position of lens holder 24 with micrometer head 34, the position of lens holder 24 is fixed with temporary fixing bolt 17 and fixing bolt 18, and micrometer head 34 is removed and reused.

[0074] FIG. 35 is a cross-sectional view showing the procedure for removing the micrometer head 34 from the lens module 4 according to the fourth embodiment. FIG. 35 includes an upper left view, an upper right view, a lower left view, and a lower right view, and the procedure progresses in the order of the upper left view, upper right view, lower left view, and lower right view as indicated by the arrows. First, as shown in the upper left view, the micrometer head 34 is used to adjust the position of the lens holder 24 in the direction of the optical axis O, and the position of the lens L2 is adjusted according to the procedure described above. Next, the temporary fixing bolt 17 is inserted into the threaded hole 14f of the lens barrel 14 from the opposite side of the micrometer head 34 to restrict movement of the lens holder 24 in the -Z direction. Next, the fixing bolt 18 is inserted into the threaded hole 35c of the micrometer head holder 35 from the same side as the micrometer head 34 to restrict movement of the lens holder 24 in the +Z direction. Next, the micrometer head 34 is removed. After this, the temporary fixing bolt 17 may be removed or may remain attached.

[0075] As described above, according to the fourth embodiment, the lens holder 24 is moved by the micrometer head 34, so that the lens holder 24 can be positioned with high precision. Furthermore, by removing, recovering, and reusing the micrometer head 34 without changing the position of the lens L2, it is possible to avoid an increase in the cost and size of the lens module 4.

[0076] In addition, the configuration of moving the lens holder 24 using the moving mechanism of embodiment 4 having the micrometer head 34 and the micrometer head holder 35 may also be applied to embodiment 2 having the flat circular ring 42 or embodiment 3 having the O-ring 43.

[0077] Embodiment 5 Fig. 36 is a cross-sectional view showing the configuration of lens module 5 according to embodiment 5. Fig. 37 is a bottom view showing the configuration of lens module 5 according to embodiment 5. Fig. 36 is a cross-sectional view taken along line XXXVI-XXXVI in Fig. 37. Fig. 38 is an exploded cross-sectional view showing the configuration of lens module 5 according to embodiment 5.

[0078] Lens module 5 includes lens assembly L consisting of two lenses L1 and L2, lens barrel 15, lens holder 25, disc spring 41 as an elastic ring, and protective washers 51 and 52. In embodiment 5, male threads 47a are formed on the outer peripheral surface of lens holder 25, and female threads 47b that engage with male threads 47a are formed on the inner peripheral surface of lens barrel 15, and lens holder 25 is moved in the direction of optical axis O and fixed in place by screw rotation of lens holder 25 relative to lens barrel 15. Male threads 47a formed on the outer peripheral surface of lens holder 25 and female threads 47b formed on the inner peripheral surface of lens barrel 15 correspond to a movement mechanism.

[0079] Lens barrel 15 has a two-stage cylindrical shape with small-diameter cylindrical portion 15a and large-diameter cylindrical portion 15b, and entirely houses lens assembly L. Lens L1 is housed on the inner circumferential surface of small-diameter cylindrical portion 15a, which has lens opening 15c. Lens L2 is housed in large-diameter cylindrical portion 15b via lens holder 25.

[0080] The lens holder 25 includes an annular portion 25b having a lens opening 25a, and a cylindrical portion 25c protruding from the annular portion 25b in the direction of the optical axis O. The cylindrical portion 25c of the lens holder 25 accommodates the lens L2 on its inner circumferential surface.

[0081] Similar to the first embodiment, the disc spring 41 applies a load to the lens L2 in the direction of insertion into the lens holder 25 (+Z direction). The disc spring 41 applies a load to the lens L1 in the direction of insertion into the lens barrel 15 (-Z direction). The protective washer 51 is interposed between the disc spring 41 and the lens L1, and is disposed on the small-diameter cylindrical portion 15a of the lens barrel 15. The protective washer 52 is interposed between the disc spring 41 and the lens L2, and is disposed on the large-diameter cylindrical portion 15b of the lens barrel 15.

[0082] Lens L1 is stored in lens barrel 15, and protective washer 51, disc spring 41, and protective washer 52 are also stored in lens barrel 15. Thereafter, lens holder 25 storing lens L2 is inserted into lens barrel 15 and screwed and rotated around optical axis O, thereby screwing it in or out toward lens barrel 15 and moving lens holder 25 in the direction of optical axis O.

[0083] As described above, according to embodiment 5, lens L2 is moved using male thread 47a formed on the outer peripheral surface of lens holder 25 and female thread 47b formed on the inner peripheral surface of lens barrel 15, making it easy to adjust the lens position and allowing the device to be realized at low cost.

[0084] In addition, the configuration of moving lens holder 25 using the moving mechanism of embodiment 5, which has a male thread 47a formed on the outer surface of lens holder 25 and a female thread 47b formed on the inner surface of barrel 15, may also be applied to embodiment 2, which has flat ring 42, or embodiment 3, which has O-ring 43.

[0085] The configurations shown in the above embodiments are examples of the contents of the present disclosure, and may be combined with other known technologies, the configurations of each embodiment may be combined as appropriate, and some of the configurations may be omitted or modified within the scope of the gist of the present disclosure. [Explanation of symbols]

[0086] 1, 2, 2a, 3, 4, 5 lens module, 11, 12, 14, 15 lens barrel, 11a, 11b, 12a, 12b, 14a, 14b, 14c, 15a, 15b, 21c, 24c, 25c cylindrical portion, 11c, 12c, 14e, 14f, 21d, 35b, 35c screw hole, 11d, 12d, 14d, 15c, 21a, 24a, 25a, 35d lens opening, 17 temporary fixing bolt, 18, 19 fixing bolt, 21, 24, 25 lens holder, 21b, 24b, 25b annular portion, 31 adjustment bolt, 34 micrometer head, 34a thimble, 35 micrometer head holder, 35a holder hole, 41 disc spring, 42 Flat ring, 43 O-ring, 47a male thread, 47b female thread, 51, 52 protective washers, 62 cap screw, L lens group, L1, L2 lenses, O optical axis.

Claims

1. a first lens and a second lens; a lens holder that accommodates the first lens; a lens barrel having one end side to house the second lens and into which the lens holder housing the first lens is inserted from the other end side; a moving mechanism that moves the lens holder in the optical axis direction; an elastic ring that is an annular elastic body interposed between the first lens and the second lens in the lens barrel and that applies a load to at least the first lens toward the other end; Equipped with A lens module characterized by:

2. The elastic ring is a disc spring. The lens module according to claim 1 .

3. The elastic ring is a flat ring. The lens module according to claim 1 .

4. The elastic ring is an O-ring. The lens module according to claim 1 .

5. The elastic ring is A load is applied to the second lens toward the one end.

5. The lens module according to claim 1, wherein the lens module is a lens module having a first surface and a second surface.

6. A protective washer is interposed between the elastic ring and the first lens, and between the elastic ring and the second lens.

4. The lens module according to claim 1, wherein the lens module is a lens module having a first surface and a second surface.

7. the moving mechanism is a bolt, The threaded portion of the bolt is engaged with the lens barrel, a bearing surface of the bolt abutting against the lens holder; The lens holder is moved in the optical axis direction by tightening or loosening the bolt.

5. The lens module according to claim 1, wherein the lens module is a lens module having a first surface and a second surface.

8. The moving mechanism includes: A micrometer head; a micrometer holder fixed to the lens barrel and holding the micrometer head; Equipped with The measurement surface of the micrometer head comes into contact with the lens holder, thereby moving the lens holder in the optical axis direction.

5. The lens module according to claim 1, wherein the lens module is a lens module having a first surface and a second surface.

9. After the lens holder is moved in the optical axis direction, the micrometer head is removed from the micrometer holder; The position of the lens holder in the optical axis direction is fixed by a bolt inserted into the micrometer holder.

9. The lens module according to claim 8.

10. the movement mechanism has a male thread formed on an outer periphery of the lens holder and a female thread formed on an inner periphery of the lens barrel, The lens holder is rotated around the optical axis to move the lens holder in the optical axis direction.

5. The lens module according to claim 1, wherein the lens module is a lens module having a first surface and a second surface.

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