JP7478599B2 - Lens unit, camera module, aperture member and manufacturing method thereof - Google Patents

Description

The present invention relates to a lens unit, camera module, aperture member, and manufacturing method thereof that constitute an in-vehicle camera mounted in a vehicle such as an automobile.

In recent years, automobiles have been equipped with on-board cameras to assist with parking and prevent collisions through image recognition, and there are also attempts to apply this to autonomous driving. Camera modules such as on-board cameras generally include a lens unit that has a lens group consisting of multiple lenses arranged along an optical axis, a barrel that houses and holds the lens group, and an aperture member that is placed between at least one of the lenses in the lens group (see, for example, Patent Document 1).

The aperture member of the lens unit adjusts (limits) the amount of light passing through, and by positioning the aperture member in an appropriate position, flare and ghosting can be appropriately suppressed, resulting in the desired optical performance.

JP 2013-231993 A

The diaphragm members that limit the amount of transmitted light include the "aperture diaphragm" that determines the F-number, which is an index of brightness, and the "light blocking diaphragm" (flare cutter) that blocks light rays that cause ghosts and light rays that cause aberrations. In all cases, however, these diaphragm members are annular, and depending on the shape of their inner periphery, they may adversely affect the optical performance of the lens unit.

For example, if the inner surface of an aperture member made of resin, SUS, or the like has defects or rough surfaces, light may be reflected and diffused at those areas. Such diffused light (stray light) may cause shower-like ghosts and deteriorate optical performance. In particular, when the aperture member is molded from resin, it may be difficult to finish the inner surface of the aperture member into the desired shape without diffused light due to burrs and other issues that arise as a result. Even under such circumstances, suppressing light reflection caused by the shape of the inner surface of the aperture member is an urgent issue in recent years, when high imaging performance that reliably eliminates stray light is required.

The present invention was made in consideration of the above circumstances, and aims to provide a lens unit, a camera module, an aperture member, and a manufacturing method thereof that can suppress light reflection caused by the inner peripheral shape of the aperture member.

In order to solve the above problems, the present invention provides a lens unit including a lens group formed by arranging a plurality of lenses along an optical axis, an annular diaphragm member for adjusting the amount of light passing through the lens group, and a cylindrical lens barrel having an inner storage space for storing and holding the lens group including the diaphragm member,
The optical absorbing resin is provided on the inner peripheral surface or the inner peripheral end of the aperture member.

According to the above-mentioned configuration of the present invention, since a light-absorbing resin is provided on the inner peripheral surface or inner peripheral end of the aperture member, light is absorbed on the inner peripheral surface or inner peripheral end of the aperture member, and therefore, the reflection and diffusion of light caused by the inner peripheral shape of the aperture member can be suppressed. As a result, the occurrence of shower-like ghosts associated with diffused light (stray light) can be suppressed, and the desired optical performance can be ensured.

In the above configuration, if there are irregularly shaped areas such as defects or rough surfaces that cause light reflection on the inner circumferential surface or inner end of the aperture member, the light absorbing resin may be partially provided on the inner circumferential surface or inner end of the aperture member so as to cover only the irregularly shaped areas, but it is preferable that the light absorbing resin is provided over the entire circumference of the inner circumferential surface or inner end of the aperture member in order to reliably suppress light reflection on the inner circumferential surface or inner end of the aperture member and eliminate stray light. In this case, it is even more preferable that the light absorbing resin is provided so as to cover the entire inner circumferential surface or inner end of the aperture member in order to reliably prevent exposure of the irregularly shaped areas.

In this way, the light absorbing resin not only suppresses the reflection and diffusion of light by covering and eliminating irregularly shaped areas on the inner circumferential surface or inner end of the aperture member that cause light reflection, but also absorbs light itself, thereby ensuring the prevention of light reflection and diffusion. However, by having a smoothly curved outer surface, it is possible to further prevent the reflection and diffusion of light and ensure the elimination of stray light.

In the above configuration, the "light-absorbing resin" refers to a resin that has the property of absorbing light, and examples of such resins include ultraviolet-curing resins and thermosetting resins. In particular, an example of a suitable ultraviolet-curing resin is Chemiseal U-2077 provided by Chemitech Co., Ltd. In addition, the light-absorbing resin preferably has a viscosity of 2000 mPa·s or more in order to increase its retention force on the inner peripheral surface or inner peripheral end of the aperture member. In the above configuration, the aperture member can be formed of, for example, resin or SUS, and includes an "aperture diaphragm" that determines the F-number, which is an index of brightness, and a "light-shielding diaphragm" (flare cutter) that blocks light rays that cause ghosts and light rays that cause aberrations.

In addition, in the above configuration, it is preferable that the inner peripheral surface or inner peripheral end of the aperture member has a locking portion for locking the light absorbing resin. This allows the light absorbing resin to be securely held on the inner peripheral surface or inner peripheral end of the aperture member by the locking portion (increasing the holding force of the light absorbing resin on the inner peripheral surface or inner peripheral end of the aperture member), making it possible to provide a permanent light reflection prevention effect. In this case, it is preferable that the locking portion includes an uneven step portion or an inclined surface.

Furthermore, when an aperture member having the above-mentioned characteristics is manufactured from resin, such a manufacturing method can include, for example, a molding step of pouring resin into a mold to form a ring-shaped molded body, a locking portion forming step of forming a locking portion including a concave-convex step or inclined surface on the inner surface or inner end portion of the molded body, a resin application step of applying a flowable light-absorbing resin to the inner surface or inner end portion of the molded body so as to lock it to the locking portion, and a resin hardening step of hardening the light-absorbing resin.
In this case, the thickness of the light absorbing resin is set to a thickness appropriate for performance, for example. The locking portion forming step can be realized by etching, machining, or the like.

The present invention also provides an aperture member and a camera module having the above-mentioned characteristics. This makes it possible to obtain the above-mentioned effects with the aperture member and the camera module.

According to the present invention, since a light-absorbing resin is provided on the inner peripheral surface or inner peripheral end of the aperture member, light is absorbed on the inner peripheral surface or inner peripheral end of the aperture member, and therefore, the reflection and diffusion of light caused by the inner peripheral shape of the aperture member can be suppressed.

1 is a schematic cross-sectional view of a lens unit according to an embodiment of the present invention. 2 is a cross-sectional view (cross-sectional view taken along line XX in FIG. 1) of a middle ring as a first aperture member provided in the lens unit in FIG. 1, taken along a direction perpendicular to the optical axis direction. FIG. 2 is an enlarged cross-sectional view of a main portion of a middle ring as a first diaphragm member provided in the lens unit of FIG. 1, and is a partial longitudinal cross-sectional view taken along the optical axis direction of part A indicated by a double-dashed line frame in FIG. 2 is an enlarged cross-sectional view of a main portion of an iris ring serving as a second diaphragm member provided in the lens unit of FIG. 1, and is a partial longitudinal cross-sectional view taken along the optical axis direction of part B indicated by a dashed double-dashed line frame in FIG. 4 is a flowchart illustrating an example of steps of a manufacturing method for manufacturing the aperture member. 2 is a schematic cross-sectional view of a camera module having the lens unit of FIG. 1.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The lens unit of the present embodiment described below is particularly intended for use as a camera module for an in-vehicle camera or the like, and is fixedly installed on the outer surface of an automobile, with wiring drawn into the automobile and connected to a display or other device. Hatching is omitted for multiple lenses in Figures 1 and 6.

Figure 1 shows a lens unit 11 according to one embodiment of the present invention. As shown in the figure, the lens unit 11 of this embodiment includes a cylindrical lens barrel 12 made of, for example, metal, and a plurality of lenses arranged in the inner storage space S of the lens barrel 12, for example, six lenses consisting of a first lens 13, a second lens 14, a third lens 15, a fourth lens 16, a fifth lens 17, and a sixth lens 18 from the object side. These lenses 13 to 18 are incorporated in the lens barrel 12 so as to be stacked with spacers 20A, 20B, 20C, and 20D between some of them. An in-vehicle camera equipped with such a lens unit 11 includes the lens unit 11, a substrate having an image sensor (not shown), and an installation member (not shown) for installing the substrate on a vehicle such as an automobile.

The lenses 13, 14, 15, 16, 17, and 18 are assembled and stored in the inner storage space S of the lens barrel 12, and are stacked and arranged with their optical axes aligned, and the lenses 13, 14, 15, 16, 17, and 18 are arranged along one optical axis O to form a group of lenses L used for imaging. In this case, the lenses 13, 14, 15, 16, 17, and 18 that make up the lens group L are all made of glass, but this is not necessary, and they may be partly made of glass and partly made of resin, or all made of resin. In this embodiment, the two fourth and fifth lenses 16 and 17 located on the image side are laminated lenses, but this is not necessary. In this embodiment, the lens barrel 12 is made of metal as described above, but it may be made of resin. In addition, the surfaces of these lenses 13, 14, 15, 16, 17, and 18 may be provided with anti-reflection films, hydrophilic films, water-repellent films, etc., as necessary.

A roughly cylindrical cap 23 is screwed onto the object-side end 12b (upper end in FIG. 1) of the lens barrel 12 as a fastening member, and the first lens 13, which is located closest to the object side, is fixed to the object-side end 12b of the lens barrel 12 by this cap 23. Specifically, the female thread 23a formed on the inner peripheral surface of the peripheral wall of the cap 23 is screwed into the male thread 12a formed on the outer peripheral surface of the object-side end 12b of the lens barrel 12, and the radially inner peripheral edge 23b of the flange-shaped upper end is abutted against the step 13b formed on the outer peripheral edge of the surface 13a facing the object side of the first lens 13. By tightening this cap 23, the first lens 13 is fixed to the object-side end 12b, and the lens group L is held in the lens barrel 12 in the optical axis direction.

The end of the lens barrel 12 on the image side (the lower end in FIG. 1) is provided with an inner flange portion 24 (which in this embodiment engages with a step provided on the image side surface of the sixth lens 18) that has an opening with an outer diameter smaller than that of the sixth lens 18. Between this inner flange portion 24 and the cap 23, the multiple lenses 13, 14, 15, 16, 17, 18 and spacers 20A, 20B, 20C, 20D that make up the lens group L are sandwiched and held in the optical axis direction.

Although not shown, an O-ring, for example, is attached as a seal member between the outer peripheral side of the first lens 13 and the lens barrel 12. This O-ring is compressed radially between the outer peripheral side of the first lens 13 and the inner peripheral surface of the object side end 12b of the lens barrel 12, thereby sealing between the object side end 12b of the lens barrel 12 and the first lens 13, thereby preventing water, dust, and other fine particles from entering the lens barrel 12 from the object side end of the lens unit 11. An outer flange portion 25 is provided in a brim shape on the outer peripheral surface of the image side of the lens barrel 12, which is used when installing the lens barrel 12 in an in-vehicle camera.

In addition, in this embodiment, some of the spacers 20A, 20B, 20C, and 20D described above also function as aperture members that adjust (limit) the amount of light passing through the lens group L. Specifically, in this embodiment, the first spacer 20A interposed between the second lens 14 and the third lens 15 is a middle ring with a pointed edge at its radially inner end that functions as a "light blocking aperture" (flare cutter) that blocks light rays that cause ghosts and light rays that cause aberrations (hence, hereinafter, the first spacer 20A will be referred to as the first aperture member 20A), and the second spacer 20B, which is positioned on the object side among the spacers interposed between the third lens 15 and the fourth lens 16, functions as a first aperture The radially inner end of the iris ring is a flat surface that functions as a "light blocking diaphragm" (flare cutter) that is thinner than the second spacer 20A (therefore, hereinafter, the second spacer 20B will be referred to as the second diaphragm member 20B), and the third spacer 20C, which is located on the image side of the spacers inserted between the third lens 15 and the fourth lens 16, functions as an "aperture diaphragm" that limits the amount of transmitted light and determines the F-number, which is an index of brightness (therefore, hereinafter, the third spacer 20C will be referred to as the third diaphragm member 20C).

Here, the first and second aperture members 20A, 20B that function as flare cutters are formed, for example, by molding resin into an annular shape (of course, they may also be formed from a metal such as SUS), and have unevenness on their inner peripheral ends or inner surfaces 20Aa, 20Ba that arise during molding (for example, irregularly shaped areas such as defective areas or rough surfaces that may cause light reflection) and/or unevenness that is intentionally formed after molding (for example, engagement portions 40, 42, described below) as shown in FIG. 2, which is a cross-sectional view taken along line X-X in FIG. 1; FIG. 3, which is a partially enlarged vertical cross-sectional view taken along the optical axis direction of portion A (the inner peripheral edge of the first aperture member 20A) shown in a dashed-dotted line frame in FIG. 1; and FIG. 4, which is a partially enlarged vertical cross-sectional view taken along the optical axis direction of portion B (the inner peripheral edge of the second aperture member 20B) shown in a dashed-dotted line frame in FIG. 1. The inner peripheral ends or inner peripheral surfaces 20Aa, 20Ba of the first and second aperture members 20A, 20B, which have such uneven portions, are provided with light-absorbing resin 30, which is a resin that absorbs light (of course, as long as the F-number can be accurately determined, light-absorbing resin 30 may also be provided on the inner peripheral surface of the third aperture member 20C).

In particular, in this embodiment, the first and second aperture members 20A and 20B are formed with locking portions 40 and 42 at their inner circumferential ends or inner circumferential surfaces 20Aa and 20Ba for locking the light absorbing resin 30 after molding, and the light absorbing resin 30 is provided on the inner circumferential ends or inner circumferential surfaces 20Aa and 20Ba so as to be locked to these locking portions 40 and 42. Specifically, in this embodiment, the first aperture member 20A has a locking portion 40 formed as an uneven step portion (for example, a step portion formed by a surface extending in the radial direction and a surface extending in the optical axis direction) at its inner circumferential end (inner circumferential edge) 20Aa as shown in FIG. 3, and the light absorbing resin 30 is locked to this locking portion 40. On the other hand, as shown in FIG. 4, the second aperture member 20B has a locking portion 42 on its inner peripheral surface 20Ba that is formed as a concave-convex inclined surface (for example, a wavy inclined surface that extends radially inward from the object side toward the image side (or in the opposite direction)), and the light-absorbing resin 30 is locked to the locking portion 42.

In this embodiment, as shown in FIG. 2 for the first aperture member 20A, the light absorbing resin 30 is provided over the entire circumference of the inner end or inner surface 20Aa, 20Ba of the aperture member 20A, 20B. As shown clearly in FIG. 3 and FIG. 4, the light absorbing resin 30 is provided so as to cover the entire inner end or inner surface 20Aa, 20Ba of the aperture member 20A, 20B, and the surface is formed into a smooth curved shape. In addition, as shown in FIG. 2, for example, it is preferable that the most protruding part (the part that performs the aperture function) of the first aperture member 20A is made of the light absorbing resin 30 over the entire circumference. This is because if the aperture member is exposed, reflections and the like will occur at that part.

In addition, when the diaphragm members 20A, 20B are formed from resin as in this embodiment, the diaphragm members 20A, 20B can be manufactured, for example, by the following manufacturing method. Specifically, for example, as shown in FIG. 5, first, resin is poured into a mold to form an annular molded body 20AA (20BA) (see FIGS. 2 to 4) (molding step S1). Then, a locking portion 40 (42) including an uneven step portion or an uneven inclined surface is formed on the inner peripheral surface or inner peripheral end of the molded body 20AA (20BA) by etching, machining, or the like (locking portion forming step S2). After the locking portion 40 (42) is formed in this way, a flowable light absorbing resin 30, for example, an ultraviolet curing resin having a viscosity of 2000 mPa·s or more, is applied to the inner peripheral end or inner peripheral surface 20Aa, 20Ba of the molded body 20AA (20BA) so as to lock it to the locking portion 40 (42) (resin application step S3). At this time, the coating thickness of the light absorbing resin 30 is set to, for example, 100 to 500 μm. If the upper limit of this setting is exceeded, sink marks will occur and the shape will become unstable, while if the lower limit of this setting is exceeded, production control will become difficult, leading to increased costs. Finally, the light absorbing resin 30 is cured to stably adhere to the inner peripheral end or inner peripheral surface 20Aa, 20Ba of the molded body 20AA (20BA) (resin curing step S4). As described above, when an ultraviolet curing resin is used as the light absorbing resin 30, ultraviolet rays are irradiated onto the ultraviolet curing resin in the resin curing step S4.

Figure 6 is a schematic cross-sectional view of a camera module 300 of this embodiment having a lens unit 11 configured as described above. As shown in the figure, this camera module 300 is configured to include the lens unit 11 of Figure 1 to which a filter 99 is attached.

The camera module 300 includes an upper case (camera case) 301, which is an exterior component, and a mount (base) 302 that holds the lens unit 11. The camera module 300 also includes a sealing member 303 and a package sensor (imaging element) 304.

The upper case 301 is a member that exposes the object side end of the lens unit 11 and covers the other parts. The mount 302 is disposed inside the upper case 301 and has a female thread 302a that screws into the male thread 11a of the lens unit 11. The seal member 303 is a member that is interposed between the inner surface 301a of the upper case 301 and the outer peripheral surface 12c of the lens barrel 12 of the lens unit 11, and is a member that maintains airtightness inside the upper case 301.

The package sensor 304 is disposed inside the mount 302, and is positioned to receive the image of the object formed by the lens unit 11. The package sensor 304 also includes a CCD, CMOS, or the like, and converts the light that is collected and reaches the package sensor 304 through the lens unit 11 into an electrical signal. The electrical signal is then converted into analog data or digital data, which is a component of the image data captured by the camera.

As described above, according to this embodiment, the light absorbing resin 30 is provided on the inner peripheral end or inner peripheral surface 20Aa, 20Ba of the aperture members 20A, 20B, so that light is absorbed by the inner peripheral end or inner peripheral surface 20Aa, 20Ba of the aperture members 20A, 20B, and therefore the reflection and diffusion of light caused by the inner peripheral shape of the aperture members 20A, 20B can be suppressed. As a result, the occurrence of shower-like ghosts associated with diffused light (stray light) can be suppressed, and the desired optical performance can be ensured.

The present invention is not limited to the above-described embodiments, and can be modified in various ways without departing from the scope of the present invention. For example, the shapes of the lenses, lens barrels, etc., in the present invention are not limited to those in the above-described embodiments. The number and shape of the aperture members in the lens unit are not limited to those in the above-described embodiments. The arrangement of the light-absorbing resin on the inner surface or inner end of the aperture member is not limited to those in the above-described embodiments. Furthermore, the above-described embodiments may be combined in part or in whole, or part of the configuration may be omitted from one of the above-described embodiments, without departing from the scope of the present invention.

11 Lens unit 12 Lens barrel 13, 14, 15, 16, 17, 18 Lens 20A, 20B, 20C Spacer (aperture member)
20Aa: Inner peripheral end portion 20Ba: Inner peripheral surface 30: Light absorbing resin 40, 42: Locking portion 300: Camera module O: Optical axis S: Inner storage space

Claims (14)

A lens unit comprising a lens group formed by arranging a plurality of lenses along an optical axis, an annular aperture member for adjusting the amount of light passing through the lens group, and a cylindrical lens barrel having an inner accommodation space for accommodating and holding the lens group including the aperture member,
a light absorbing resin is provided on an inner peripheral surface or an inner peripheral end portion of the aperture member;
A lens unit characterized in that an inner peripheral surface or an inner peripheral end portion of the diaphragm member has a locking portion for locking the light absorbing resin . 2. The lens unit according to claim 1 , wherein the locking portion is a stepped portion or an inclined surface having a concave-convex shape. 3. The lens unit according to claim 1, wherein the light absorbing resin is provided over the entire circumference of an inner peripheral surface or an inner peripheral end portion of the diaphragm member. 4. The lens unit according to claim 3 , wherein the light absorbing resin is provided so as to cover the entire inner peripheral surface or the entire inner peripheral end portion of the diaphragm member. 5. The lens unit according to claim 1, wherein the surface of the light absorbing resin is formed into a smoothly curved shape. 6. The lens unit according to claim 1, wherein the diaphragm member has a most protruding portion with respect to the optical axis, which performs a diaphragm function, and the most protruding portion is made of the light absorbing resin over the entire circumference. A camera module comprising the lens unit according to any one of claims 1 to 6 . An annular aperture member that is provided in an optical system and adjusts the amount of light passing through, the annular aperture member having an inner peripheral surface or an inner peripheral end portion provided with a light absorbing resin ;
A diaphragm member , characterized in that the inner peripheral surface or the inner peripheral end has a locking portion for locking the light absorbing resin . 9. The aperture member according to claim 8 , wherein the engaging portion is a stepped portion or an inclined surface having a concave-convex shape. 10. The aperture member according to claim 8, wherein the light absorbing resin is provided over the entire circumference of an inner peripheral surface or an inner peripheral end portion of the aperture member. 11. The aperture member according to claim 10 , wherein the light absorbing resin is provided so as to cover the entire inner peripheral surface or the entire inner peripheral end portion of the aperture member. 12. The aperture member according to claim 8, wherein the surface of the light absorbing resin is formed into a smoothly curved shape. 13. The diaphragm member according to claim 8, wherein the most protruding portion with respect to the optical axis, which performs the diaphragm function, is made of the light absorbing resin over the entire periphery. A method for manufacturing a diaphragm member that is provided in an optical system and adjusts the amount of light passing therethrough, comprising the steps of:
A molding step of pouring resin into a mold to form an annular molded body;
a locking portion forming step of forming a locking portion including a concave-convex step portion or an inclined surface on an inner peripheral surface or an inner peripheral end portion of the molded body;
a resin application step of applying a flowable light absorbing resin to an inner peripheral surface or an inner peripheral end portion of the molded body so as to lock the resin to the locking portion;
a resin curing step of curing the light absorbing resin;
A manufacturing method comprising the steps of:

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