JP2018045203A - Infrared lens module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an infrared lens module in which a foreign substance adhering to a lens surface can be removed while suppressing increase in the manufacturing cost.SOLUTION: An infrared lens module 1 includes a lens 10 that transmits infrared rays and a lens barrel 50 holding the lens 10. The lens 10 includes: an incident surface 11 that is the surface where infrared rays are incident; and a back surface 12 as an opposite surface to the incident surface 11. The lens barrel 50 includes: a regulation surface 23 that is located on the incident surface 11 side of the lens 10 and regulates the incident range of light to the lens 10; and an end surface 25 that is connected to the regulation surface 23 and includes a region 27 where the height along an optical axis C of the lens 10 on the incident surface 11 side of the lens 10 is highest. In a cross-section including the optical axis C of the lens 10, an angle α formed by the plane along the end surface 25 and the optical axis C is an acute angle.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an infrared lens module.

  Infrared lens modules that include a lens that transmits infrared rays are used in infrared cameras for imaging with infrared rays. The infrared camera can be used as an in-vehicle camera, for example. In-vehicle cameras are often installed outside the vehicle, and foreign matters such as raindrops and dust may adhere to the front of the camera. When such a foreign substance adheres to the front surface of the camera, the foreign substance is reflected in the image taken by the in-vehicle camera, and a problem arises that a clear image cannot be obtained.

  On the other hand, a technique for removing a foreign object by installing a wiper device, a blower device, a cleaning device, or the like in a lens module has been proposed (for example, see Patent Documents 1 to 3).

JP2013-81097A JP 2012-168457 A JP 2012-35654 A

  However, in the countermeasures disclosed in Patent Documents 1 to 3, it is necessary to install a new device for removing foreign substances in the lens module. Therefore, the problem that the manufacturing cost of a lens module rises arises.

  Accordingly, an object of the present invention is to provide an infrared lens module capable of removing foreign substances adhering to the lens surface while suppressing an increase in manufacturing cost.

  An infrared lens module according to the present invention includes a lens that transmits infrared light and a lens barrel that holds the lens. The lens includes an incident surface that is a surface on which infrared rays are incident, and a rear surface that is a surface opposite to the incident surface. The lens barrel is located on the incident surface side of the lens and is connected to the defining surface that defines the light incident range on the lens and the defining surface, and the height along the optical axis of the lens on the lens incident surface side is the highest. And an end surface including a high region. In the cross section including the optical axis of the lens, the angle formed by the surface along the end surface and the optical axis is an acute angle.

  According to the infrared lens module, it is possible to provide an infrared lens module capable of removing foreign substances adhering to the lens surface while suppressing an increase in manufacturing cost.

2 is a schematic cross-sectional view showing a structure of an infrared lens module according to Embodiment 1. FIG. 2 is a schematic plan view showing the structure of an infrared lens module according to Embodiment 1. FIG. 6 is a schematic plan view showing a structure of an infrared lens module according to Embodiment 2. FIG. 6 is a schematic plan view showing a structure of an infrared lens module according to Embodiment 3. FIG.

[Description of Embodiment of Present Invention]
First, embodiments of the present invention will be listed and described. The infrared lens module of the present application includes a lens that transmits infrared light and a lens barrel that holds the lens. The lens includes an incident surface that is a surface on which infrared rays are incident, and a rear surface that is a surface opposite to the incident surface. The lens barrel is located on the incident surface side of the lens and is connected to the defining surface that defines the light incident range on the lens and the defining surface, and the height along the optical axis of the lens on the lens incident surface side is the highest. And an end surface including a high region. In the cross section including the optical axis of the lens, the angle formed by the surface along the end surface and the optical axis is an acute angle.

  The present inventor does not install a new device, but considers a method for removing foreign substances adhering to the lens surface by an airflow from the front obtained when used as a component of an in-vehicle camera, for example. It was. As a result, when a lens barrel including a defining surface that defines the light incident range on the lens and an end surface connected to the defining surface is employed, the angle formed by the surface along the end surface and the optical axis is an acute angle. By adopting a simple lens barrel shape, it has been found that the airflow from the front can be used effectively and foreign matters adhering to the lens surface can be removed.

  In the infrared lens module of the present application, in the cross section including the optical axis of the lens, the angle formed by the surface along the end surface and the optical axis is an acute angle. As a result, by effectively using the airflow from the front, it is possible to remove foreign substances adhering to the surface of the lens without installing a new device. Thus, according to the infrared lens module of the present application, it is possible to provide an infrared lens module capable of removing foreign substances adhering to the lens surface while suppressing an increase in manufacturing cost.

  In the infrared lens module, in a cross section including the optical axis of the lens, an angle formed between the surface along the end surface and the optical axis may be larger than an angle formed between the surface along the predetermined surface and the optical axis. By doing in this way, the foreign material adhering to the surface of a lens can be removed, without affecting the incident range of the light to a lens.

  In the infrared lens module, the material constituting the lens may be zinc sulfide (ZnS). A lens composed of ZnS has a small change in refractive index with respect to a temperature change. Therefore, an infrared lens module that is stable against changes in the external temperature can be obtained.

[Details of the embodiment of the present invention]
Next, an embodiment of an infrared lens module according to the present invention will be described below with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

(Embodiment 1)
1 is a schematic cross-sectional view showing a cross section including the optical axis of the lens module according to Embodiment 1. FIG. FIG. 2 is a schematic plan view showing a state in which the lens module according to Embodiment 1 is viewed from the incident surface side.

  With reference to FIGS. 1 and 2, the infrared lens module 1 according to the first embodiment includes a lens 10 and a lens barrel 50.

  The lens 10 is an infrared lens that transmits infrared light, more specifically, light having a wavelength of 8 μm to 14 μm. The material constituting the lens 10 is, for example, ZnS. The lens 10 includes a first lens surface 11 as an incident surface, a second lens surface 12 as a back surface, and an outer peripheral surface 13. The first lens surface 11 includes a central region 11A that is a convex surface that is located at the center and intersects the optical axis C, and an outer edge region 11B that is a plane surrounding the central region 11A. The second lens surface 12 includes a central region 12A that is a concave surface that is located at the center and intersects the optical axis C, and an outer edge region 12B that is a plane surrounding the central region 12A.

  The lens barrel 50 includes a cap 20 and a lens barrel body 30. The lens barrel body 30 has a hollow cylindrical shape. The lens barrel body 30 supports the lens 10 by contacting the outer edge region 12B and the outer peripheral surface 13 of the second lens surface 12 at the end. In the present embodiment, the lens barrel body 30 is made of a metal such as a resin or an aluminum alloy.

  The cap 20 has a cylindrical shape in which a protruding portion 29 that protrudes toward the inner peripheral side is formed at one end portion. The cap 20 is made of a metal such as an aluminum alloy. The outer peripheral surface 26 of the cap 20 has a cylindrical surface shape. The protruding portion 29 of the cap 20 and the outer edge region 11B of the first lens surface 11 are in contact with each other. Further, the cap 20 is fixed to the lens barrel main body 30 in a state where the end of the lens barrel main body 30 is fitted at the end opposite to the side on which the protruding portion 29 is formed. In this way, the lens 10 is held by the lens barrel 50.

  The inner peripheral surface of the cap 20 is in contact with the boundary portion between the central region 11A and the outer edge region 11B of the first lens surface 11, and the first tapered surface 21 has a smaller inner diameter as the distance from the outer edge region 11B increases. And a second tapered surface 23 that is connected to the surface 21 and has an inner diameter that increases with distance from the outer edge region 11B in the optical axis C direction. The first taper surface 21 and the second taper surface 23 are connected at an annular first connection portion 22. The first connecting portion 22 is a region having the smallest diameter on the inner peripheral surface of the cap 20. Each of the first tapered surface 21 and the second tapered surface 23 has a conical surface shape. The second tapered surface 23 is a defining surface that is located on the first lens surface 11 side of the lens 10 and that defines the incident range of light to the lens 10. The end surface 25 is connected to the second tapered surface 23 at the annular second connection portion 24. The end surface 25 includes a third connection portion 27 that is a connection portion between the outer peripheral surface 26 and the end surface 25, which is a region having the highest height along the optical axis C on the first lens surface 11 side of the lens 10.

  The angle α formed by the surface along the end face 25 and the optical axis C is an acute angle (less than 90 °). That is, the end face 25 becomes smaller in the optical axis C direction as it approaches the optical axis C. If it demonstrates from another viewpoint, the end surface 25 has the conical surface shape which inclines toward the inner peripheral side.

  By adopting such a shape of the cap 20, when an air flow from the direction of the optical axis C is applied to the first lens surface 11, the wind speed in the vicinity of the first lens surface 11, particularly in the vicinity of the first connection portion 22, is increased. growing. As a result, it is possible to remove foreign matter adhering to the surface of the lens 10 without using a new device by effectively using the airflow from the front. As described above, the infrared lens module 1 according to the present embodiment is an infrared lens module capable of removing foreign substances adhering to the lens surface while suppressing an increase in manufacturing cost.

  In the present embodiment, the angle α formed by the surface along the end face 25 and the optical axis C is larger than the angle β formed by the surface along the second tapered surface 23 and the optical axis C. By adopting such a structure, foreign matter adhering to the surface of the lens 10 can be removed without affecting the light incident range on the lens 10.

(Embodiment 2)
Next, a second embodiment which is another embodiment will be described. FIG. 3 is a schematic plan view of the lens module according to the second embodiment and corresponds to FIG. 2 of the first embodiment.

  Referring to FIG. 3, infrared lens module 1 in the second embodiment has basically the same structure as in the first embodiment, and has the same effects. However, the infrared lens module 1 according to the second embodiment is different from the first embodiment in that the groove portion 31 is formed in the cap 20.

  Specifically, in the infrared lens module 1 according to the second embodiment, a groove 31 that penetrates the end surface 25 and the second tapered surface 23 in the radial direction is formed. A plurality of groove portions 31 (four in the present embodiment) are formed at equal intervals in the circumferential direction. Each of the groove portions 31 extends linearly when viewed in plan from the optical axis C direction. By forming such a groove portion 31, in the infrared lens module 1 of Embodiment 2, the wind speed in the vicinity of the first lens surface 11 is further increased.

(Embodiment 3)
Next, Embodiment 3 which is still another embodiment will be described. FIG. 4 is a schematic plan view of the lens module according to the third embodiment and corresponds to FIGS. 2 and 3 of the first and second embodiments.

  Referring to FIG. 4, infrared lens module 1 in the fourth embodiment basically has the same structure as that in the second embodiment, and has the same effects. However, the infrared lens module 1 according to the third embodiment is different from the second embodiment in the shape of the groove 31.

  Specifically, in the infrared lens module 1 according to the third embodiment, the groove portion 31 extends in a curved shape (arc shape) when viewed in plan from the optical axis C direction. By adopting such a groove shape, it is possible to prevent light from entering the lens 10 through the groove portion 31.

  As in Embodiments 2 and 3, by making α an acute angle and forming the groove 31, the airflow from the front can be used effectively, but the formation of the groove 31 is possible even when α is 90 °. It is valid. The groove part 31 may be formed by cutting, for example, or may be formed by a forging molding or a casting mold. Further, a member in which the groove portion 31 is formed may be separately manufactured, and the member may be attached to the cap 20. Such a member can be produced, for example, by injection molding a resin material.

In the cap 20 having the same structure as the above-described embodiment, the height h ₂ of the first tapered surface 21 in the direction along the optical axis C _(unit: mm), the height of the second tapered surface 23 h _{1 (unit:} mm), and a simulation experiment for estimating the wind speed in the vicinity of the lens surface (in the vicinity of the first connecting portion 22) when the angle θ (unit: °) formed by the surface perpendicular to the optical axis C and the surface along the end surface 25 is changed. went. The wind speed was derived under the condition that an air flow of 13.8 m / s (corresponding to 50 km / h) was applied to the first lens surface 11 from the direction along the optical axis C. In addition, the wind speed was estimated in the same manner when the same groove 31 as in the second embodiment was formed. The experimental results are shown in Table 1.

表１において、第１テーパ面２１および第２テーパ面２３の高さは、レンズ１０の有効径で除して規格化した値を示している。また、θについては、次の式（１）の関係が成立する。
α＝９０°−θ・・・（１）
また、ｈ_２／Ｄが０である場合とは、第１テーパ面２１が存在せず、第２テーパ面２３において最も直径の小さい領域が第１レンズ面１１に接触する場合を意味する。Ｎｏ．１０および１１は、実施の形態２と同様の溝部３１を形成した場合に対応する。

In Table 1, the heights of the first taper surface 21 and the second taper surface 23 indicate values normalized by dividing by the effective diameter of the lens 10. For θ, the relationship of the following formula (1) is established.
α = 90 ° −θ (1)
Further, the case where h ₂ / D is 0 means that the first tapered surface 21 does not exist and the region having the smallest diameter in the second tapered surface 23 contacts the first lens surface 11. No. 10 and 11 correspond to the case where the same groove 31 as in the second embodiment is formed.

Referring to Table 1, no. 1 and No. 4 and no. 2 and No. 5, no. 7 and no. From the comparison with FIG. 8, it is confirmed that by setting θ to a positive value, that is, by setting α to an acute angle, the wind speed near the lens increases. From this, it is confirmed that according to the infrared lens module of the present application in which α is an acute angle, the airflow from the front can be used effectively. No. 3, no. 4 and no. From the comparison of 5, it is confirmed that the wind speed in the vicinity of the lens increases by decreasing h ₁ / D. No. 2, No. 5, no. 6, no. 7, no. 8 and no. From the comparison of 9, it can be confirmed that the wind speed in the vicinity of the lens increases by making α an acute angle regardless of the magnitude of h ₂ / D. No. 10 and no. 11, even when the groove 31 is formed, it is confirmed that the wind speed is increased by setting α to an acute angle.

  It should be understood that the embodiments and examples disclosed herein are illustrative in all respects and are not restrictive in any respect. The scope of the present invention is defined by the scope of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the scope of the claims.

  The infrared lens module of the present application can be particularly advantageously applied to an infrared lens module that is used in an environment where foreign matter may adhere to the lens.

DESCRIPTION OF SYMBOLS 1 Infrared lens module 10 Lens 11 1st lens surface 11A Central area | region 11B Outer edge area | region 12 2nd lens surface 12A Central area 12B Outer edge area | region 13 Outer peripheral surface 20 Cap 21 1st taper surface 22 1st connection part 23 2nd taper surface 24 1st 2 connecting portion 25 end face 26 outer peripheral surface 27 third connecting portion 29 projecting portion 30 lens barrel body 31 groove portion 50 lens barrel

Claims (3)

A lens that transmits infrared rays;
A lens barrel that holds the lens,
The lens is
An incident surface which is a surface on which infrared rays are incident;
A back surface that is a surface opposite to the incident surface,
The lens barrel is
A defining surface that is located on the incident surface side of the lens and defines a light incident range on the lens;
An end surface that is connected to the defining surface and includes a region having the highest height along the optical axis of the lens on the incident surface side of the lens, and
An infrared lens module, wherein an angle formed by a surface along the end surface and the optical axis is an acute angle in a cross section including the optical axis of the lens.   2. The infrared ray according to claim 1, wherein, in a cross section including the optical axis of the lens, an angle formed by a surface along the end surface and the optical axis is larger than an angle formed by a surface along the prescribed surface and the optical axis. Lens module.   The infrared lens module according to claim 1 or 2, wherein a material constituting the lens is zinc sulfide.

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