WO2018186103A1

WO2018186103A1 - Lens unit

Info

Publication number: WO2018186103A1
Application number: PCT/JP2018/009031
Authority: WO
Inventors: 大樹吉田
Original assignee: 富士フイルム株式会社
Priority date: 2017-04-05
Filing date: 2018-03-08
Publication date: 2018-10-11
Also published as: CN110520775A; JP6739629B2; JPWO2018186103A1; CN110520775B

Abstract

This lens unit has: a cylindrical lens barrel formed from a resin material which contains inorganic fibers; and contained components including a plurality of lenses contained in the lens barrel while being arranged side by side in the optical axis direction, at least one of the lenses being formed from a resin material. The amount of thermal expansion of the lens barrel in the optical axis direction is set equal to the sum of the amounts of thermal expansion of the contained components in the optical axis direction, or the amount of thermal expansion of the lens barrel in the direction perpendicular to the optical axis direction is set equal to the amount of the thermal expansion, in the direction perpendicular to the optical axis direction, of the lens formed from the resin material.

Description

Lens unit

This disclosure relates to a lens unit.

In recent years, attempts have been made to construct the lens barrel or lens of a lens unit from a resin material from the viewpoint of cost reduction and moldability. For example, Japanese Unexamined Patent Application Publication No. 2016-184081 discloses a lens unit having a lens barrel made of a resin material reinforced with glass fibers (inorganic fibers).

However, a lens barrel made of a resin material generally has a larger coefficient of thermal expansion than a lens barrel made of a metal such as aluminum, and particularly when the lens barrel is made of a resin material containing inorganic fibers, Anisotropy occurs in the coefficient of thermal expansion between the direction in which the resin material flows and the direction perpendicular thereto. For this reason, when the housing part such as the lens and the lens housed in the lens barrel is thermally expanded due to a rise in external temperature, for example, when the thermal expansion amount of the lens barrel is larger than the thermal expansion amount of the housing component, There is a possibility that the position of the lens may be shifted due to an increase in the distance between the lenses.

On the other hand, for example, when the thermal expansion amount of the housing component is larger than the thermal expansion amount of the lens barrel, a compression stress is generated in the lens, so that the lens is easily plastically deformed, and the interval between the lenses is reduced when the external temperature returns to room temperature. There is a possibility that the position of the lens is shifted due to the clearance. In particular, when the lens that is the housing component is made of a resin material, the lens is easily subjected to compressive stress due to the thermal expansion of the lens being restrained by the lens barrel due to the difference in thermal expansion between the lens barrel and the lens.

The present disclosure is intended to provide a lens unit that can suppress the occurrence of compressive stress in the lens when the external temperature rises in consideration of the above facts.

A lens unit according to a first aspect of the present disclosure includes a cylindrical lens barrel made of a resin material containing an inorganic fiber, and a plurality of lenses housed in the lens barrel side by side in the optical axis direction. The lens has a housing component made of a resin material, and the thermal expansion amount of the lens barrel in the optical axis direction is equal to the sum of the thermal expansion amounts of the housing component in the optical axis direction.

In particular, when the lens barrel is made of a resin material containing inorganic fibers, anisotropy occurs in the thermal expansion coefficient of the lens barrel, so that the position of the lens as the housing component is shifted, or the thermal expansion of the lens is restricted by the lens barrel. This tends to cause compressive stress on the lens.

Here, according to the above configuration, by making the thermal expansion amount in the optical axis direction of the lens barrel equal to the sum of the thermal expansion amounts in the optical axis direction of the housing components, there is a space between the lenses or compression stress on the lenses. Can be prevented from occurring. Note that “the amount of thermal expansion in the optical axis direction is equal” means that the difference in the amount of thermal expansion is within ± 15 μm. The amount of thermal expansion is calculated by multiplying the length of the member by the coefficient of thermal expansion of the member.

A lens unit according to a second aspect of the present disclosure includes a cylindrical lens barrel made of a resin material containing inorganic fibers, and a plurality of lenses accommodated in the optical axis direction in the lens barrel, and includes at least one lens The lens is made of a resin material, and the amount of thermal expansion in the optical axis direction of the barrel is equal to the sum of the amounts of thermal expansion in the optical axis direction of the barrel, and the optical axis direction of the barrel The amount of thermal expansion in the direction perpendicular to is equal to the amount of thermal expansion in the direction perpendicular to the optical axis direction of the lens made of a resin material.

According to the above configuration, the thermal expansion amount in the optical axis direction of the lens barrel is equal to the sum of the thermal expansion amounts in the optical axis direction of the housing component, and the thermal expansion amount in the direction perpendicular to the optical axis direction of the lens barrel is The amount of thermal expansion in the direction perpendicular to the optical axis direction of the lens made of a resin material is made equal. For this reason, lens displacement can be further suppressed and compression stress applied to the lens compared to a configuration in which only one of the thermal expansion amount in the optical axis direction and the thermal expansion amount in the direction perpendicular to the optical axis is made equal. Can be further suppressed.

The lens unit according to the third aspect of the present disclosure is the lens unit according to the first aspect or the second aspect, wherein the thermal expansion amount in the optical axis direction of the lens barrel is subtracted from the total thermal expansion amount in the optical axis direction of the housing component. The difference in thermal expansion amount is set to 0 μm or more and 10 μm or less.

According to the above configuration, the difference in thermal expansion amount obtained by subtracting the thermal expansion amount in the optical axis direction of the lens barrel from the total thermal expansion amount in the optical axis direction of the housing component is set to 0 μm or more and 10 μm or less. For this reason, the positional deviation of the lens can be suppressed as compared with the case where the difference in thermal expansion is smaller than 0 μm, and the occurrence of compressive stress in the lens is suppressed as compared with the case where the difference in thermal expansion is larger than 10 μm. be able to.

A lens unit according to a fourth aspect of the present disclosure includes a cylindrical lens barrel made of a resin material containing an inorganic fiber, and a plurality of lenses housed in the lens barrel side by side in the optical axis direction. The lens has a housing part made of a resin material, and the thermal expansion amount in the direction perpendicular to the optical axis direction of the lens barrel is equal to the thermal expansion amount in the direction perpendicular to the optical axis direction of the lens made of the resin material. Has been.

According to the above configuration, by making the thermal expansion amount in the direction perpendicular to the optical axis direction of the lens barrel equal to the thermal expansion amount in the direction perpendicular to the optical axis direction of the lens made of a resin material, the axes of the lenses are shifted. Or compressive stress is generated in the lens. Note that “the amount of thermal expansion in the direction perpendicular to the optical axis direction is equal” means that the difference in the amount of thermal expansion is within ± 10 μm.

A lens unit according to a fifth aspect of the present disclosure is the lens unit according to the fourth aspect. In the lens unit according to the fourth aspect, the amount of thermal expansion in the direction perpendicular to the optical axis direction of the lens made of a resin material in the direction perpendicular to the optical axis direction of the lens barrel. The difference in thermal expansion amount after subtracting the thermal expansion amount is set to 0 μm or more and 10 μm or less.

According to the above configuration, the difference in thermal expansion amount obtained by subtracting the thermal expansion amount in the direction perpendicular to the optical axis direction of the lens barrel from the thermal expansion amount in the direction perpendicular to the optical axis direction of the lens made of the resin material is 0 μm or more and 10 μm. It is as follows. For this reason, it is possible to suppress the deviation of the axes of the lenses compared to the case where the difference in thermal expansion is smaller than 0 μm, and the compression stress is generated in the lens compared to the case where the difference in thermal expansion is larger than 10 μm. Can be suppressed.

The lens unit according to the sixth aspect of the present disclosure is the lens unit according to any one of the first to third aspects, and the housing component includes a lens made of a glass material.

Generally, a lens made of a glass material has a smaller thermal expansion coefficient than a lens made of a resin material and a lens barrel. Here, since the housing component has a lens made of a glass material, the total thermal expansion amount of the housing component in the optical axis direction can be adjusted by the lens made of the glass material.

A lens unit according to a seventh aspect of the present disclosure is the lens unit according to the sixth aspect, wherein the thermal expansion coefficient in the optical axis direction of the lens barrel is smaller than the thermal expansion coefficient in the optical axis direction of the lens made of a resin material, and It is larger than the thermal expansion coefficient in the optical axis direction of a lens made of a glass material.

According to the above configuration, the thermal expansion coefficient in the optical axis direction of the lens barrel is smaller than the thermal expansion coefficient in the optical axis direction of the lens made of the resin material, and larger than the thermal expansion coefficient in the optical axis direction of the lens made of the glass material. For this reason, the total of the thermal expansion amount in the optical axis direction of the housing component relative to the thermal expansion amount of the lens barrel can be adjusted by the lens made of the glass material and the lens made of the resin material.

The lens unit according to an eighth aspect of the present disclosure is the lens unit according to any one of the first aspect to the third aspect, the sixth aspect, and the seventh aspect. The housing component is a resin material containing inorganic fibers. And an interval ring for defining an interval between the plurality of lenses.

According to the above configuration, the spacing ring made of a resin material containing inorganic fibers is provided between the lenses. For this reason, the sum total of the thermal expansion amount of the optical component in the optical axis direction of the housing component can be adjusted by adjusting the thermal expansion amount of the spacing ring.

The lens unit according to the ninth aspect of the present disclosure is the lens unit according to the eighth aspect. The lens or the spacing ring has a flat surface extending in a direction perpendicular to the optical axis direction, and the lens and the spacing ring, or The lenses are in contact with each other on a flat surface.

According to the above configuration, the lens and the spacing ring, or the lenses are in surface contact with each other on a flat surface extending in the direction perpendicular to the optical axis. For this reason, compared with the configuration in which the lens and the interval ring, or the lenses are in point contact with each other, it is possible to suppress stress concentration on one point of the lens or the interval ring at the time of thermal expansion of the lens or the interval ring. It can suppress that a lens or a space | interval ring inclines with respect to an optical axis.

The lens unit according to a tenth aspect of the present disclosure is the lens unit according to any one of the first to ninth aspects, wherein the thermal expansion coefficient in a direction perpendicular to the optical axis direction of the lens barrel is It is larger than the thermal expansion coefficient in the optical axis direction.

According to the above configuration, the thermal expansion coefficient in the vertical direction of the optical axis of the lens barrel is larger than the thermal expansion coefficient in the optical axis direction of the lens barrel. Can be tolerated.

The lens unit according to an eleventh aspect of the present disclosure is the lens unit according to any one of the first aspect to the tenth aspect. The thermal expansion coefficient of the lens barrel is the amount of inorganic fibers contained or the inorganic fibers. It is adjusted by changing the orientation.

According to the above configuration, the amount of thermal expansion of the lens barrel can be adjusted to the amount of thermal expansion of the housing component by adjusting the amount of inorganic fibers contained or the direction of the inorganic fibers.

The lens unit according to the twelfth aspect of the present disclosure is the lens unit according to any one of the first to tenth aspects, and the lens barrel is made of at least two kinds of resin materials.

When adjusting the thermal expansion coefficient of the lens barrel by adjusting the content of inorganic fibers, there is a limit to the adjustment range, and when adjusting the thermal expansion coefficient of the lens barrel by adjusting the orientation of inorganic fibers It takes time and effort to adjust the gate position. Here, according to the above configuration, since the lens barrel is made of two or more kinds of resin materials, the thermal expansion coefficient of the lens barrel can be adjusted by mixing a plurality of types of resin materials having different thermal expansion coefficients. . For this reason, compared with the case where the content of inorganic fiber and the orientation of inorganic fiber are adjusted, the thermal expansion coefficient can be easily adjusted.

The lens unit according to the thirteenth aspect of the present disclosure is a lens unit according to any one of the first to twelfth aspects and is mounted on a vehicle-mounted camera or a surveillance camera.

The lens unit of the present disclosure is installed in cameras that are exposed to high temperatures and difficult to maintain imaging performance, such as in-vehicle cameras installed in the car and surveillance cameras installed outdoors. Particularly useful as a lens unit.

According to the present disclosure, it is possible to suppress the occurrence of compressive stress in the lens when the external temperature increases.

It is an exploded sectional view showing the whole lens unit composition concerning an example of an embodiment. It is sectional drawing which shows the state before thermal expansion of the lens unit which concerns on an example of embodiment. It is sectional drawing which shows the state after the thermal expansion of the lens unit which concerns on an example of embodiment.

Hereinafter, an example of an embodiment of a lens unit according to the present disclosure will be described with reference to FIGS. 1, 2A, and 2B. In the figure, the Z direction indicates a direction horizontal to the optical axis, that is, the optical axis direction, and the Y direction indicates a direction perpendicular to the optical axis, that is, the optical axis vertical direction or radial direction.

The lens unit 10 according to this embodiment is exposed to high temperatures such as a surveillance camera installed outdoors or an in-vehicle camera installed inside a vehicle, and is difficult to maintain imaging performance. Mounted on the camera used. As shown in FIG. 1, the lens unit 10 includes a lens barrel 12, an accommodating component 14 accommodated in the lens barrel 12, and an imaging module 16 fixed to the lens barrel 12.

<Configuration of the lens barrel>
As an example, the lens barrel 12 is a cylinder having the optical axis direction (Z direction) as the central axis direction, and is configured by injection molding a resin material containing inorganic fibers (hereinafter referred to as “inorganic-containing resin”). Has been. Examples of the inorganic fiber include glass fiber, carbon fiber, inorganic filler, and the like, and the strength of the lens barrel 12 is increased by the inorganic fiber.

In the lens barrel 12 of the present embodiment, the orientation of the inorganic fibers is substantially the same as the optical axis direction. Generally, the resin material is less likely to expand in the direction horizontal to the fiber direction as compared to the direction perpendicular to the fiber direction of the inorganic fiber. For this reason, the lens barrel 12 has a thermal expansion coefficient in the direction perpendicular to the optical axis that is greater than the thermal expansion coefficient in the optical axis direction.

For example, when the lens barrel 12 is molded, a resin injection gate is formed on the imaging module 16 side (the other end side in the optical axis direction), and the resin material is allowed to flow along the optical axis direction, whereby the inorganic fibers are moved along the optical axis. Can be oriented in the direction. Specifically, for example, the thermal expansion coefficient in the optical axis direction of the lens barrel 12 is about 10 ppm to 30 ppm, and the thermal expansion coefficient in the direction perpendicular to the optical axis is about 50 ppm to 60 ppm.

As a resin material constituting the lens barrel 12, for example, polyamide, polyacetal, polycarbonate, polyphenylene ether, polybutylene terephthalate, polyethylene terephthalate, polyethylene, syndiotactic polystyrene, polysulfone, polyethersulfone, polyphenylene sulfide, polyarylate, polyamide It is possible to use at least one selected from the group consisting of imide, polyetherimide, polyetheretherketone, acrylonitrile butadiene distyrene, polyolefin, and each modified polymer, or a polymer alloy containing at least one selected from the group. it can.

The lens barrel 12 is more preferably made of at least two kinds of resin materials having different thermal expansion coefficients among the above resin materials. By constituting the lens barrel 12 with two or more kinds of resin materials mixed together, the thermal expansion coefficient of the lens barrel 12 can be adjusted.

Furthermore, since the lens barrel 12 is required to have high light shielding properties and light absorption properties, the resin material used is preferably black, and the resin material preferably contains a black pigment or a black dye. By configuring the lens barrel 12 with a resin material containing a black pigment or a black dye, the inner peripheral surface 12A of the lens barrel 12 can be made black, and more visible light can be reflected on the inner peripheral surface 12A of the lens barrel 12. It can be effectively suppressed.

The lens barrel 12 has a cylindrical portion 18 having an opening 18A on one end side (left end side in FIG. 1) in the optical axis direction that is the light incident side, and the other optical axis direction other end side that is the light emission side of the cylindrical portion 18. And a bottom wall portion 20 that covers (the right end side in FIG. 1).

A caulking portion 18B that is bent toward the inside in the radial direction of the lens barrel 12 by heat caulking is formed at the peripheral portion of the opening 18A of the tube portion 18 of the lens barrel 12, and the opening is opened in the state after the heat caulking. The portion 18A has a circular shape when viewed from the optical axis direction. On the other hand, an opening 20A having an inner diameter smaller than the opening 18A is formed through the bottom wall 20 of the lens barrel in the optical axis direction.

The inner peripheral surface 12A of the lens barrel 12 is circular when viewed from the optical axis direction, and the inner diameter gradually decreases from one end side of the lens barrel 12 in the optical axis direction toward the other end side in the optical axis direction. Yes. An accommodating portion 22 for accommodating the accommodating component 14 is formed between the opening 18A and the opening 20A in the lens barrel 12.

<Configuration of housing parts>
As illustrated in FIG. 1, the housing component 14 includes, as an example, a first lens 24, a second lens 26, a third lens 28, and a first lens disposed in order from one end side in the optical axis direction in the housing portion 22 of the lens barrel 12. 4 lenses 30 and a fifth lens 32 (hereinafter, the first lens 24 to the fifth lens 32 may be collectively referred to as “

lenses

24, 26, 28, 30, 32”).

In addition, between the first lens 24 and the second lens 26, the second lens 26 and the third lens 28, and the fourth lens 30 and the fifth lens 32 in the housing portion 22 of the lens barrel 12, a spacing ring 34, respectively. 36 and 38 are provided.

As an example, the first lens 24 and the second lens 26 are made of a glass material, and each has a circular shape when viewed from the optical axis direction. Note that the thermal expansion coefficient in the optical axis direction and the thermal expansion coefficient in the optical axis vertical direction of the first lens 24 and the second lens 26 made of a glass material are uniform, and the first lens 24 and the second lens 26 have a uniform thermal expansion coefficient. The thermal expansion coefficient is smaller than the thermal expansion coefficient in the optical axis direction of the lens barrel 12. Specifically, for example, the thermal expansion coefficients of the first lens 24 and the second lens 26 are about 7 ppm.

For example, the first lens 24 is a plano-convex lens in which one end surface in the optical axis direction is a convex surface and the other end surface in the optical axis direction is a flat surface 24C, and the outer peripheral surface is recessed inward in the radial direction of the first lens 24. A stepped portion 24A is formed. As shown in FIGS. 2A and 2B, a rubber seal material 40 is fitted over the entire circumference of the stepped portion 24A.

As shown in FIG. 1, the second lens 26 includes a lens portion 26A and a peripheral edge portion 26B projecting radially outward from the lens portion 26A. The lens portion 26A of the second lens 26 is, for example, an aspherical convex lens in which both end surfaces in the optical axis direction are aspherical convex surfaces. Further, both end surfaces in the optical axis direction of the peripheral edge portion 26B of the second lens 26 are flat surfaces 26C extending in a direction perpendicular to the optical axis direction.

As an example, the third lens 28, the fourth lens 30, and the fifth lens 32 are made of a resin material and each have a circular shape when viewed from the optical axis direction. The third lens 28, the fourth lens 30, and the fifth lens 32 made of a resin material have a uniform thermal expansion coefficient in the optical axis direction and a thermal expansion coefficient in the direction perpendicular to the optical axis. The thermal expansion coefficients of the fourth lens 30 and the fifth lens 32 are larger than the thermal expansion coefficient in the optical axis direction of the lens barrel 12. Specifically, for example, the thermal expansion coefficients of the third lens 28, the fourth lens 30, and the fifth lens 32 are about 70 ppm.

The third lens 28, the fourth lens 30, and the fifth lens 32 include

lens portions

28A, 30A, and 32A, and

peripheral portions

28B and 30B that protrude outward in the radial direction from the

lens portions

28A, 30A, and 32A. 32B.

As an example, the lens portion 28A of the third lens 28 and the lens portion 32A of the fifth lens 32 are planoconvex lenses in which one end surface in the optical axis direction is a convex surface and the other end surface in the optical axis direction is a horizontal surface. As an example, the lens portion 30A of the fourth lens 30 is a biconvex lens in which both end surfaces in the optical axis direction are convex surfaces.

In addition, both end surfaces in the optical axis direction of the

peripheral portions

28B, 30B, and 32B of the third lens 28, the fourth lens 30, and the fifth lens 32 are

flat surfaces

28C, 30C that extend in a direction perpendicular to the optical axis direction, respectively. The third lens 28 and the fourth lens 30 are in contact with each other at the

flat surfaces

28C and 30C.

The spacing rings 34, 36, and 38 are annular members as viewed from the optical axis direction, and are made of an inorganic-containing resin as an example. As the resin material and the inorganic fiber constituting the spacing rings 34, 36, and 38, the same material as the resin material and the inorganic fiber constituting the lens barrel 12 may be used, or different materials may be used.

Specifically, as in the case of the lens barrel 12, as a resin material constituting the spacing rings 34, 36, 38, polyamide, polyacetal, polycarbonate, polyphenylene ether, polybutylene terephthalate, polyethylene terephthalate, polyethylene, syndiotactic polystyrene, polysulfone , Polyethersulfone, polyphenylene sulfide, polyarylate, polyamide imide, polyether imide, polyether ether ketone, acrylonitrile budadiene styrene, polyolefin, and each modified polymer, or at least one selected from the group A polymer alloy containing at least one selected can be used.

The spacing rings 34, 36, 38 may be made of a metal material such as aluminum. In this case, the thermal expansion coefficient of the spacing rings 34, 36, 38 is, for example, about 23 ppm. Further, one or two of the spacing rings 34, 36, and 38 may be made of an inorganic-containing resin, and the other may be made of a metal material.

Both end surfaces in the optical axis direction of the spacing rings 34, 36, and 38 are

flat surfaces

34A, 36A, and 38A extending in a direction perpendicular to the optical axis direction, respectively. Thereby, the flat surface 34A of the spacing ring 34 abuts on the flat surface 24C of the first lens 24 and the flat surface 26C of the second lens 26, respectively, so that the first lens 24 and the second lens 26 in the optical axis direction are in contact with each other. The interval is specified.

Similarly, the flat surface 36A of the spacing ring 36 comes into contact with the flat surface 26C of the second lens 26 and the flat surface 28C of the third lens 28, so that the second lens 26 and the third lens 28 in the optical axis direction are in contact with each other. The interval is specified. Further, the flat surface 38A of the spacing ring 38 abuts on the flat surface 30C of the fourth lens 30 and the flat surface 32C of the fifth lens 32, respectively, so that the distance between the fourth lens 30 and the fifth lens 32 in the optical axis direction. Is stipulated.

Here, the sum of the thermal expansion amounts of the housing component 14 in the optical axis direction is equal to the thermal expansion amount of the lens barrel 12 in the optical axis direction. In addition, among the housing components 14, the thermal expansion amounts of the third lens 28, the fourth lens 30, and the fifth lens 32 made of a resin material having the largest thermal expansion amount in the direction perpendicular to the optical axis are the optical axes of the lens barrel 12. The amount of thermal expansion in the vertical direction is made equal.

Specifically, as shown in FIG. 2A, the length in the optical axis direction of the housing portion 22 of the lens barrel 12 when the external temperature of the lens unit 10 is room temperature (40 ° C. as an example) is P1, and the housing portion 22 (mirror The width in the direction perpendicular to the optical axis of the smallest inner diameter portion of the cylinder 12 is defined as Q1. Further, the total length of the housing component 14 in the optical axis direction, that is, the first lens 24, the second lens 26, the third lens 28, the fourth lens 30, the fifth lens 32, and the interval rings 34, 36, 38. The sum of the lengths R1, R2, R3, R4, R5, R6, R7, and R8 in the optical axis direction is S1, and the width of the fifth lens 32 in the optical axis vertical direction is T1.

On the other hand, as shown in FIG. 2B, the length in the optical axis direction of the housing portion 22 of the lens barrel 12 when the external temperature of the lens unit 10 is high (for example, 125 ° C.) is P2, and the housing portion 22 (of the lens barrel 12). The width in the direction perpendicular to the optical axis of the minimum inner diameter portion) is Q2. Further, the total sum of the lengths of the housing components 14 in the optical axis direction is S2, and the width of the fifth lens 32 in the optical axis vertical direction is T2.

At this time, the sum of the thermal expansion amounts of the housing component 14 in the optical axis direction, that is, the difference S2-S1 in the optical axis direction of the housing component 14 at high temperature and room temperature is the heat in the optical axis direction of the lens barrel 12. The amount of expansion, that is, the difference P2-P1 in length in the optical axis direction of the lens barrel 12 at high temperature and at room temperature is made equal.

In the present embodiment, “the amount of thermal expansion in the optical axis direction is equal” means that the thermal expansion amount in the optical axis direction of the barrel 12 from the sum S2-S1 of the thermal expansion amounts in the optical axis direction of the housing component 14. This means that the difference in thermal expansion (S2−S1) − (P2−P1) minus P2−P1 is within ± 15 μm.

Since the difference in thermal expansion in the optical axis direction is within ± 15 μm, the resolution of the lens unit 10 can be increased, and the lens unit 10 having a resolution compatible with the middle end model can be obtained. Here, the “middle end model” refers to a model having the performance of about 1.3M or more pixels.

Note that the difference in thermal expansion (S2-S1)-(P2-P1) obtained by subtracting the thermal expansion amount P2-P1 in the optical axis direction of the lens barrel 12 from the sum S2-S1 of the thermal expansion amounts in the optical axis direction of the housing component 14 ) Is more preferably 0 μm or more and 10 μm or less. By setting the difference in thermal expansion in the optical axis direction to 0 μm or more and 10 μm or less, the positional deviation of the

lenses

24, 26, 28, 30, and 32 in the lens barrel 12 compared to the case where the difference in thermal expansion is smaller than 0 μm. Can be suppressed.

Further, it is possible to suppress the occurrence of compressive stress in the

lenses

24, 26, 28, 30, and 32 as compared with the case where the difference in thermal expansion is larger than 10 μm. Thereby, the resolution of the lens unit 10 can be increased, and the lens unit 10 having a resolution compatible with a high-end model can be obtained. Here, the “high-end model” refers to a model having a performance of about 2.0M or more.

Further, the thermal expansion amount of the fifth lens 32 (and the third lens 28 and the fourth lens 30) in the direction perpendicular to the optical axis, that is, the fifth lens 32 (and the third lens 28 and the fourth lens 30 at high temperature and room temperature). ) In the vertical direction of the optical axis of the lens barrel 12 is a thermal expansion amount in the vertical direction of the optical axis of the lens barrel 12, that is, a difference in width Q2-Q1 in the vertical direction of the optical axis of the lens barrel 12 at high temperature and room temperature. Is equal to.

In the present embodiment, “the amount of thermal expansion in the direction perpendicular to the optical axis is equal” means that the lens made of a resin material, that is, the third lens 28, the fourth lens 30, and the fifth lens 32 in the direction perpendicular to the optical axis. The difference in thermal expansion (T2-T1)-(Q2-Q1) obtained by subtracting the thermal expansion amount Q2-Q1 in the direction perpendicular to the optical axis of the lens barrel 12 from the thermal expansion amount T2-T1 in FIG. Say that.

Since the difference in thermal expansion in the direction perpendicular to the optical axis is within ± 10 μm, the resolution of the lens unit 10 can be increased, and the lens unit 10 having a resolution compatible with the middle end model can be obtained.

Note that the difference in thermal expansion (T2-T1) − (Q2−) obtained by subtracting the thermal expansion amount Q2−Q1 in the optical axis vertical direction of the lens barrel 12 from the thermal expansion amount T2−T1 in the optical axis vertical direction of the fifth lens 32. More preferably, Q1) is 0 μm or more and 10 μm or less. By setting the difference in thermal expansion in the direction perpendicular to the optical axis to be 0 μm or more and 10 μm or less, the axes of the

lenses

24, 26, 28, 30, and 32 in the lens barrel 12 are compared with the case where the difference in thermal expansion is less than 0 μm. Can be prevented from shifting.

Further, it is possible to suppress the occurrence of compressive stress in the

lenses

24, 26, 28, 30, and 32 as compared with the case where the difference in thermal expansion is larger than 10 μm. Thereby, the resolution of the lens unit 10 can be increased, and the lens unit 10 having a resolution compatible with a high-end model can be obtained.

<Configuration of imaging module>
The imaging module 16 converts light (image of the object M shown in FIGS. 2A and 2B) that has reached through the housing component 14 into an electrical signal, and is a CMOS (Complementary Metal Oxide Semiconductor) image sensor or a CCD (Charge Coupled Device). ) It has an image sensor 16A such as an image sensor. The converted electrical signal is converted into analog data or digital data, which is image data.

The imaging module 16 is supported by a holder (not shown) and is fixed to the other end side (light emission side) in the optical axis direction from the bottom wall portion 20 of the barrel 12, and the imaging element 16 </ b> A is located inside the barrel 12. It is arranged at the imaging point of the optical system of the housing component 14.

<Assembly method>
When assembling the lens unit 10, as shown in FIG. 1, the fifth lens 32, the spacing ring 38, and the fourth in order from the bottom wall 20 side (the other end side in the optical axis direction) in the housing portion 22 of the barrel 12. The lens 30, the third lens 28, the spacing ring 36, the second lens 26, the spacing ring 34, and the first lens 24 fitted with the sealing material 40 are fitted. At this time, the gap between the first lens 24 and the inner peripheral surface 12A of the lens barrel 12 is sealed by compressing the sealing material 40 in the radial direction.

Thereafter, the caulking portion 18B is formed by heat caulking the peripheral portion of the opening 18A of the tube portion 18 of the barrel 12 with a jig (not shown). At this time, the housing component 14 is fixed in the housing portion 22 of the lens barrel 12 by the crimping portion 18B. Further, the imaging module 16 is fixed to the lens barrel 12 by a holder (not shown).

According to the present embodiment, the thermal expansion amount of the lens barrel 12 in the optical axis direction is made equal to the total thermal expansion amount of the housing component 14 in the optical axis direction. For this reason, it is possible to suppress the interval between the

lenses

24, 26, 28, 30, and 32 and the occurrence of compressive stress in the

lenses

24, 26, 28, 30, and 32.

Further, the thermal expansion amount in the direction perpendicular to the optical axis of the lens barrel 12 is made equal to the thermal expansion amount in the direction perpendicular to the optical axis of the third lens 28, the fourth lens 30, and the fifth lens 32 made of a resin material. For this reason, it can suppress that the axis | shaft of

lenses

24, 26, 28, 30, and 32 shift | deviates, and that a compressive stress arises in the

lenses

24, 26, 28, 30, and 32.

In the present embodiment, the thermal expansion amount in the optical axis direction of the lens barrel 12 and the sum of the thermal expansion amounts in the optical axis direction of the housing component 14 are equalized, and the thermal expansion amount in the direction perpendicular to the optical axis of the lens barrel 12 is The third lens 28, the fourth lens 30, and the fifth lens 32 have the same amount of thermal expansion in the direction perpendicular to the optical axis.

For this reason, as compared with the configuration in which only one of the thermal expansion amount in the optical axis direction and the thermal expansion amount in the vertical direction of the optical axis is equal, the positional deviation of the

lenses

24, 26, 28, 30, and 32 is further increased. It can suppress, and it can suppress more that compressive stress arises in

lenses

24, 26, 28, 30, and 32. Thereby, the fall of the resolution of the lens unit 10 can be suppressed, and it becomes useful especially as the lens unit 10 mounted in the vehicle-mounted camera, the surveillance camera installed outdoors, etc.

Further, according to the present embodiment, the thermal expansion coefficient of the lens barrel 12 in the direction perpendicular to the optical axis is set to be larger than the thermal expansion coefficient in the optical axis direction. For this reason, thermal expansion in the direction perpendicular to the optical axis can be allowed while suppressing thermal expansion in the optical axis direction of the lens barrel 12.

In addition, as a method of adjusting the thermal expansion coefficient (thermal expansion amount) of the lens barrel 12, for example, a method of changing the amount of inorganic fibers contained or the orientation of the inorganic fibers can be mentioned. Moreover, the method of changing the kind or mixing ratio of the resin material which comprises the lens-barrel 12 is mentioned.

When adjusting the thermal expansion coefficient of the lens barrel 12 by adjusting the content of inorganic fibers, there is a limit to the adjustment range, and when adjusting the thermal expansion coefficient of the lens barrel 12 by adjusting the orientation of the inorganic fibers It takes time and effort to adjust the position of the gate for resin material injection. Here, it is possible to easily adjust the thermal expansion coefficient by mixing two or more kinds of resin materials and configuring the lens barrel 12 as compared with the case of adjusting the content of inorganic fibers and the orientation of inorganic fibers. Can do.

Further, as a method of adjusting the thermal expansion amount of the housing component 14 in the optical axis direction, for example, the material and the number of the

lenses

24, 26, 28, 30, and 32 are changed, or between the

lenses

24, 26, 28, 30, and 32 And the like (the length of the spacing rings 34, 36, 38 in the optical axis direction).

Specifically, the thermal expansion coefficient in the optical axis direction of the lens barrel 12 is smaller than that of the third lens 28, the fourth lens 30, and the fifth lens 32 made of a resin material, and the first lens 24 made of a glass material, the first lens 24, and the like. 2 is larger than the lens 26.

For this reason, for example, by adjusting the number of

lenses

28, 30, 32 made of resin material and the number of

lenses

24, 26 made of glass material, the amount of thermal expansion of the

lenses

28, 30, 32 made of resin material can be made from glass material. The total amount of thermal expansion in the optical axis direction of the housing component 14 can be matched with the thermal expansion amount in the optical axis direction of the lens barrel 12 by canceling with the thermal expansion amounts of the

lenses

24 and 26.

Also, the spacing rings 34, 36, 38 made of an inorganic-containing resin are made of a metal material, the amount or orientation of the contained inorganic fibers is adjusted, or the types of resin materials that make up the spacing rings 34, 36, 38 Alternatively, by changing the mixing ratio, the amount of thermal expansion of the spacing rings 34, 36, 38 can be adjusted, and the total amount of thermal expansion in the optical axis direction of the housing component 14 can be adjusted.

In the present embodiment, the

lenses

24, 26, 28, 30, 32 and the spacing rings 34, 36, 38 are flat surfaces 24 </ b> C, 26 </ b> C, extending in the direction perpendicular to the optical axis in the housing portion 22 of the lens barrel 12. 28C, 30C, 32C, 34A, 36A, and 38A are in surface contact with each other.

Therefore, the

lenses

24, 26, 28, 30, 32 and the interval rings 34, 36, 38 are in point contact with each other, and the

lenses

24, 26, 28, 30, 32, or the intervals during thermal expansion. The concentration of stress at one point of the

rings

34, 36, 38 can be suppressed, and the

lenses

24, 26, 28, 30, 32 or the spacing rings 34, 36, 38 can be prevented from being inclined with respect to the optical axis. be able to.

(Other embodiments)
In addition, although an example of embodiment was demonstrated about this indication, this indication is not limited to this embodiment, Other various embodiment is possible within the scope of this indication.

For example, in the above embodiment, the housing component 14 has five

lenses

24, 26, 28, 30, and 32, but the number of lenses is not limited to five. The first lens 24 and the second lens 26 may be made of a resin material, and the third lens 28, the fourth lens 30, and the fifth lens 32 may be made of a glass material.

Further, the number of the spacing rings 34, 36, 38 and the number of sealing members 40 is not limited to the above embodiment, and a fixing (not shown) is provided between the

lenses

24, 26, 28, 30, 32 and the spacing rings 34, 36, 38. A member may be provided. The fixing member is, for example, a thin film made of black resin (polyethylene terephthalate) attached to the

flat surfaces

24C, 26C, 28C, 30C, and 32C of the

lenses

24, 26, 28, 30, and 32. In addition, a diaphragm member and a light shielding plate (not shown) may be provided.

Further, in the above embodiment, the thermal expansion amount in the optical axis direction of the lens barrel 12 and the sum of the thermal expansion amounts in the optical axis direction of the housing component 14 are equalized, and the thermal expansion in the vertical direction of the optical axis of the lens barrel 12 is made. The amount of thermal expansion of the third lens 28, the fourth lens 30, and the fifth lens 32 in the direction perpendicular to the optical axis was made equal.

However, one of the thermal expansion amount in the optical axis direction and the thermal expansion amount in the optical axis vertical direction may be equalized. By making either one equal, it is possible to suppress a decrease in resolution of the lens unit 10 as compared with a configuration in which the thermal expansion amount in the optical axis direction and the thermal expansion amount in the optical axis vertical direction are not equal.

In the above embodiment, the

lenses

24, 26, 28, 30, 32 and the spacing rings 34, 36, 38 are in surface contact with each other on the

flat surfaces

24C, 26C, 28C, 30C, 32C, 34A, 36A, 38A. It was. However, for example, a plurality of convex portions may be formed to protrude from the

flat surfaces

34A, 36A, 38A of the spacing rings 34, 36, 38, and the convex portions may be in contact with the

lenses

24, 26, 28, 30, 32.

By forming convex portions on the spacing rings 34, 36, 38 and making the

lenses

24, 26, 28, 30, 32 and the spacing rings 34, 36, 38 make point contact, the contact portion is compared with the configuration in which surface contact is made. That is, it becomes easy to increase the dimensional accuracy of the tip of the convex portion, and the compressive stress generated in the

lenses

24, 26, 28, 30, 32 can be reduced.

In the above embodiment, the inner peripheral surface 12A of the lens barrel 12 is circular as viewed from the optical axis direction. However, for example, the inner peripheral surface 12A of the lens barrel 12 is polygonal when viewed from the optical axis direction, and the inner peripheral surface 12A of the lens barrel 12 and the outer peripheral surfaces of the

lenses

24, 26, 28, 30, 32 are brought into multipoint contact. It is good also as a structure.

As a result, the thermal expansion in the direction perpendicular to the optical axis of the

lenses

24, 26, 28, 30, and 32 is greater than in the configuration in which the entire inner peripheral surface 12 A is in surface contact with the

lenses

24, 26, 28, 30, and 32. Restraining by the lens barrel 12 can suppress the occurrence of compressive stress in the

lenses

24, 26, 28, 30, and 32.

Hereinafter, an example of the embodiment of the present disclosure will be described in detail with reference to examples. An example of the embodiment of the present disclosure should not be construed as being limited by the following example.

[Comparative Example 1]
In Comparative Example 1, a lens unit in which the thermal expansion amount in the optical axis direction and the thermal expansion amount in the vertical direction of the optical axis are not equal is used. The lens unit includes a lens barrel made of a kind of inorganic-containing resin, a lens made of a resin material, a lens made of a glass material, and a housing part including a spacing ring made of a resin material.

[Example 1]
In Example 1, a lens unit in which only the amount of thermal expansion in the direction perpendicular to the optical axis was made equal was used. The lens barrel of the lens unit is made of two kinds of inorganic-containing resins, and the configuration other than the lens barrel is the same as that of the lens unit of Comparative Example 1. Specifically, the amount of thermal expansion in the direction perpendicular to the optical axis of the lens barrel was adjusted to the amount of thermal expansion in the direction perpendicular to the optical axis of the lens made of a resin material by adjusting the content of inorganic fibers in the lens barrel.

[Example 2]
In Example 2, a lens unit in which the thermal expansion amount in the optical axis direction and the thermal expansion amount in the optical axis vertical direction are both equal is used. The interval ring of the lens unit is made of an inorganic-containing resin, and the configuration other than the interval ring is the same as that of the lens unit of the first embodiment. Specifically, in addition to the conditions of Example 1, by adjusting the content of the inorganic fibers in the spacing ring, the thermal expansion amount in the optical axis direction of the housing component is matched with the thermal expansion amount in the optical axis direction of the lens barrel. It was.

[Example 3]
In Example 3, in addition to the conditions of Example 1, a lens unit in which the thermal expansion amount in the optical axis direction of the housing component is matched with the thermal expansion amount in the optical axis direction of the barrel by using an aluminum spacing ring. Using. The configuration other than the interval ring is the same as that of the lens units of the first and second embodiments.

Here, the thermal expansion amounts of the lens barrel, the interval ring, and the lens are calculated by multiplying the lengths of the lens barrel, the interval ring, and the lens by the thermal expansion coefficients of the lens barrel, the interval ring, and the lens, respectively. The coefficient of thermal expansion is the amount of dimensional change in the optical axis direction and the optical axis vertical direction when the external temperature is changed from 23 ° C. to 125 ° C. for the lens barrel, the spacing ring, and the lens that are actually molded. Is calculated by converting the dimensional change amount into a dimensional change rate per unit temperature.

<Evaluation method of resolution degradation by heat test>
The amount of resolution degradation before and after the heat resistance test of the lens unit was evaluated by the following procedure. First, the resolution of the lens unit before the heat resistance test is measured. Next, the lens unit is stored in a thermostatic apparatus at 105 ° C. or 125 ° C. for 1000 hours, further taken out to room temperature and allowed to stand for 2 hours, and then the resolution is measured. This is the resolution after the heat resistance test. For the 15 lens units, the amount of resolution deterioration after the heat resistance test is calculated before the heat resistance test, and the amount of deterioration of the lens unit with the largest amount of deterioration is adopted as the evaluation value of the resolution deterioration amount. The resolution in this evaluation was performed using an MTF (Modulation transfer function) measuring machine, and the MTF value measured at a spatial frequency of 60 lp / mm at the central field angle of the lens unit was used as the resolution evaluation value.

<Comparison of resolution degradation amount>
First, using the lens units of Example 1 and Comparative Example 1, the amount of resolution degradation in a heat resistance test at 105 ° C. was compared. When the resolution degradation amount is 0% to -5%, evaluation A, when the resolution degradation amount is -5% to -30%, evaluation B, and when the resolution degradation amount is -30% to -60% Evaluation C was designated. The evaluation A has the same performance as when all the lenses of the housing component are made of a glass material. The comparison results are shown in Table 1.

From Table 1, the lens unit in which only the thermal expansion amount in the optical axis vertical direction is equal is compared with the lens unit in which both the thermal expansion amount in the optical axis direction and the thermal expansion amount in the optical axis vertical direction are not equal. It can be seen that a decrease (degradation) in resolution is suppressed.

Next, using the lens units of Examples 1 to 3, the resolution degradation amount in the heat resistance test at 125 ° C. was compared. When the resolution degradation amount is 0% to -10%, evaluation A, when the resolution degradation amount is -10% to -40%, evaluation B, and when the resolution degradation amount is -40% to -60% Evaluation C was designated. The evaluation A has the same performance as when all the lenses of the housing component are made of a glass material. The comparison results are shown in Table 2.

From Table 2, the lens unit in which the thermal expansion amount in the optical axis direction in addition to the thermal expansion amount in the optical axis vertical direction is equal is compared with the lens unit in which only the thermal expansion amount in the optical axis vertical direction is equal, It can be seen that the reduction (degradation) of the resolution is further suppressed.

The disclosure of Japanese Patent Application No. 2017-0775493 filed on Apr. 5, 2017 is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference, Incorporated herein by reference.

DESCRIPTION OF SYMBOLS 10 Lens unit 12 Lens barrel 12A Inner peripheral surface 14 Accommodating part 16 Imaging module 16A Imaging element 18 Cylinder part

18A Opening part

18B Caulking part 20 Bottom wall part 20A Opening part 22 Receiving part 24 First lens 24A Step part 24C Flat surface 26 First 2 lens 26A lens part 26B peripheral part 26C flat surface 28 third lens 28A lens part 28B peripheral part 28C flat surface 30 fourth lens 30A lens part 30B peripheral part 30C flat surface 32 fifth lens 32A lens part 32B peripheral part 32C flat surface 34 Space ring 34A Flat surface 36 Space ring 36A Flat surface 38 Space ring 38A Flat surface 40 Sealing material

Claims

A cylindrical lens barrel made of a resin material containing inorganic fibers;
A plurality of lenses housed in the optical axis direction in the lens barrel, and at least one lens housing part made of a resin material;
Have
The amount of thermal expansion in the optical axis direction of the lens barrel is equal to the total amount of thermal expansion in the optical axis direction of the housing component.
Lens unit.
A cylindrical lens barrel made of a resin material containing inorganic fibers;
A plurality of lenses housed in the optical axis direction in the lens barrel, and at least one lens housing part made of a resin material;
Have
The thermal expansion amount in the optical axis direction of the lens barrel is equal to the sum of the thermal expansion amounts in the optical axis direction of the housing component, and the thermal expansion amount in the direction perpendicular to the optical axis direction of the lens barrel is a resin material. The amount of thermal expansion in the direction perpendicular to the optical axis direction of the lens consisting of
Lens unit.
The thermal expansion amount difference obtained by subtracting the thermal expansion amount in the optical axis direction of the lens barrel from the total thermal expansion amount in the optical axis direction of the housing component is set to 0 μm or more and 10 μm or less. Lens unit.
A cylindrical lens barrel made of a resin material containing inorganic fibers;
A plurality of lenses housed in the optical axis direction in the lens barrel, and at least one lens housing part made of a resin material;
Have
The amount of thermal expansion in the direction perpendicular to the optical axis direction of the lens barrel is equal to the amount of thermal expansion in the direction perpendicular to the optical axis direction of the lens made of a resin material.
Lens unit.
The difference in thermal expansion amount obtained by subtracting the thermal expansion amount in the direction perpendicular to the optical axis direction of the lens barrel from the thermal expansion amount in the direction perpendicular to the optical axis direction of the lens made of a resin material is 0 μm or more and 10 μm or less. The lens unit according to claim 4.
The lens unit according to any one of claims 1 to 3, wherein the housing component includes a lens made of a glass material.
The thermal expansion coefficient in the optical axis direction of the lens barrel is smaller than the thermal expansion coefficient in the optical axis direction of the lens made of a resin material and larger than the thermal expansion coefficient in the optical axis direction of the lens made of a glass material. 6. The lens unit according to 6.
8. The housing part according to claim 1, wherein the housing part is made of a resin material containing inorganic fibers, and has a spacing ring that defines a spacing between the plurality of lenses. Lens unit.
The lens or the spacing ring has a flat surface extending in a direction perpendicular to the optical axis direction,
The lens unit according to claim 8, wherein the lens and the interval ring, or the lenses are in contact with each other on the flat surface.
10. The lens unit according to claim 1, wherein a thermal expansion coefficient in a direction perpendicular to the optical axis direction of the lens barrel is larger than a thermal expansion coefficient in the optical axis direction of the lens barrel.
The lens unit according to any one of claims 1 to 10, wherein a thermal expansion coefficient of the lens barrel is adjusted by changing an amount of inorganic fibers contained or an orientation of inorganic fibers.
The lens unit according to any one of claims 1 to 10, wherein the lens barrel is made of at least two kinds of resin materials.
The lens unit according to any one of claims 1 to 12, which is mounted on a vehicle-mounted camera or a surveillance camera.