JP7779658B2 - Film-coated lens, lens unit and camera module - Google Patents

Description

The present invention relates to a film-equipped lens, lens unit, and camera module that are particularly used in vehicle cameras mounted on vehicles such as automobiles.

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

Anti-reflection coatings (AR coatings) are typically applied to the surfaces of the lenses that make up such lens units, for example by vapor deposition, to increase their transmittance. Furthermore, when the anti-reflection coating has a multi-layer structure, it is generally possible to achieve the desired low reflectance conditions over a wide wavelength range by alternately stacking films made of low-refractive index material and films made of high-refractive index material.

JP 2013-231993 A

However, when an anti-reflection coating is deposited by vapor deposition, depending on the deposition method, the thickness of the anti-reflection coating in the radially outer region may be thinner than the thickness of the radially inner region (resulting in non-uniform deposition), due in part to the curvature of the lens surface on which the coating is to be deposited. In particular, in a multilayer structure, such a non-uniformly thinly deposited anti-reflection coating region results in high reflectivity in the visible range (resulting in poor anti-reflection characteristics in the visible range). Specifically, for example, for the same incident light angle, the spectral characteristic curve shown in a spectral characteristic diagram illustrating the relationship between the reflectivity (%) of the anti-reflection coating and the wavelength (nm) of incident light is shifted toward shorter wavelengths in the radially outer region of the anti-reflection coating compared to the radially inner region of the anti-reflection coating that is uniformly deposited and has the desired anti-reflection characteristics. As a result, the reflectivity does not fall completely below the specified value within the specified incident wavelength range (e.g., the visible light range from 450 nm to 650 nm) (the visible light reflectance becomes high). As a result, such anti-reflection coatings have poor peripheral light intensity ratios and do not achieve the desired optical characteristics (anti-reflection characteristics).

Thus, even if the radially inner region of the anti-reflection coating is deposited in the desired layered state, if the radially outer region of the anti-reflection coating is deposited unevenly and thinly relative to the radially inner region, the anti-reflection characteristics will differ between the radially inner and radially outer regions at the same light incidence angle (the desired anti-reflection characteristics will not be obtained in the radially outer region), making it difficult to achieve the desired overall optical performance. Of course, this problem can be resolved, for example, by depositing the anti-reflection coating so that it satisfies the anti-reflection characteristics of both the radially inner and radially outer regions, i.e., so that it meets the desired low reflectivity conditions over a wide wavelength range. However, this requires the use of a multilayer structure in which films of low-refractive index material and films of high-refractive index material are alternately layered, as described above, resulting in a significant increase in film thickness. If the film thickness increases significantly, the anti-reflection coating may be unable to withstand deformation when the lens expands due to exposure to a high-temperature environment, such as during high-temperature testing, and cracks may form on the film surface. These cracks can then cause ghosting and adversely affect the optical characteristics.

The present invention was made in consideration of the above circumstances, and aims to provide a coated lens, lens unit, and camera module with an anti-reflection coating that can provide the desired anti-reflection characteristics within a specified incident wavelength range across the entire inner and outer radial regions without significantly increasing the film thickness over the entire area.

In order to solve the above-mentioned problems, the present invention provides a film-coated lens that is provided in a lens barrel and has an anti-reflection film formed on its surface,
the anti-reflection film has a first anti-reflection film portion on the inner side in the radial direction and a second anti-reflection film portion on the outer side in the radial direction, the first anti-reflection film portion having different anti-reflection properties from the second anti-reflection film portion,
The second anti-reflection film portion is characterized by having anti-reflection properties in which, at a predetermined first light incident angle, the reflectance is higher than that of the first anti-reflection film portion within a specified incident wavelength range, and, at a second light incident angle larger than the first light incident angle, the reflectance is lower than that of the first anti-reflection film portion within a specified incident wavelength range.

According to the above configuration, the anti-reflection film is composed of a first anti-reflection film portion on the radially inner side and a second anti-reflection film portion on the radially outer side, which have different anti-reflection properties, and the anti-reflection properties of the second anti-reflection film portion are set so that at a predetermined first light incident angle, the reflectance is higher than that of the first anti-reflection film portion within a specified incident wavelength range, and at a second light incident angle larger than the first light incident angle, the reflectance is lower than that of the first anti-reflection film portion within a specified incident wavelength range (in other words, at a predetermined first light incident angle, the second anti-reflection film portion has a higher reflectance than the first anti-reflection film portion within a specified incident wavelength range). The antireflection characteristics of the first antireflection coating portion are set so that the reflectance of the first antireflection coating portion is lower than that of the antireflection coating portion and is higher than that of the second antireflection coating portion within a specified incident wavelength range at a second light incident angle larger than the first light incident angle; alternatively, the reflectance of the first antireflection coating portion is lower than that of the second antireflection coating portion within a specified incident wavelength range at a specified first light incident angle, and the reflectance of the second antireflection coating portion is lower than that of the first antireflection coating portion within a specified incident wavelength range at a second light incident angle larger than the first light incident angle. Specifically, the anti-reflection film is divided into the inner and outer radial regions by forming separate anti-reflection film sections appropriate for each region so that the anti-reflection characteristics required for each region of the lens are met. Specifically, the outer radial region, which generally has a relatively large light incidence angle (particularly applicable to lenses such as camera lenses with concave-convex spherical lens configurations), exhibits high transmittance at large light incidence angles, while the inner radial region, which has a relatively small light incidence angle, exhibits high transmittance at small light incidence angles. This allows the desired anti-reflection characteristics to be achieved within a specified incident wavelength range throughout the entire inner and outer radial regions. This avoids the problem of the anti-reflection characteristics of the outer radial region being degraded due to the thin film state of the outer radial region, which occurs when the anti-reflection film has the same film layer configuration throughout the entire inner and outer radial regions. Furthermore, it is not necessary to employ a thick multilayer structure for the anti-reflection film to achieve the desired low reflectance requirement over a wide wavelength band, thereby satisfying the anti-reflection characteristics of both the inner and outer radial regions.

In addition, in this type of anti-reflection coating, the second anti-reflection coating portion generally has a greater thickness than the first anti-reflection coating portion. In this case, the first anti-reflection coating portion and the second anti-reflection coating portion may have the same film layer configuration but different film thicknesses in the multilayer structure, or may have different film layer configurations. In the above configuration, the extent of each of the radially outer and inner regions of the anti-reflection coating is determined by the curvature and effective diameter of the lens; the greater the lens curvature, the smaller the extent of the radially inner region. Here, the effective diameter of the lens refers to the diameter of a circle whose radius is the distance from the optical axis of the light ray passing through the lens surface at the position farthest from the optical axis.

It is also preferable that the first anti-reflection film portion and the second anti-reflection film portion do not overlap each other. In this case, the boundary between the first anti-reflection film portion and the second anti-reflection film portion may form a gap or a step, or may form a transition portion that gradually transitions from the first anti-reflection film portion to the second anti-reflection film portion. However, the present invention does not exclude the first anti-reflection film portion and the second anti-reflection film portion overlapping each other. If they overlap each other, the lower layer of the second anti-reflection film portion in the multilayer structure may be constituted by the first anti-reflection film portion.

In the above configuration, the anti-reflection coating is applied, for example, by vapor deposition, within at least the optically effective range (effective diameter) of the lens. In the above configuration, the coated lens with the anti-reflection coating may be made of glass or resin. In the above configuration, the anti-reflection coating may be applied not only to the surface of the lens facing the object side, but also to the back surface of the lens facing the image side. In the above configuration, the "specified incident wavelength range" is preferably the wavelength range of visible light, particularly 450 nm to 650 nm. The first light incident angle may be, for example, 0°, and the second light incident angle may be, for example, 45°.

In addition, in the above-described configuration of the present invention, when the coated lens has, on the image side, a radially inner central surface that is spherically concave toward the object side and an annular outer peripheral surface that extends radially outward from the outer edge of this central surface, it is preferable that, within the lens effective diameter, a first anti-reflection coating portion is formed on the central surface and a second anti-reflection coating portion is formed from the radially outer region of the central surface to the radially inner region of the outer peripheral surface. In the above-described configuration of the present invention, it is preferable that the first anti-reflection coating portion has lower incidence angle dependence than the second anti-reflection coating portion within a predetermined first light incidence angle range, and that the second anti-reflection coating portion has lower incidence angle dependence than the first anti-reflection coating portion within a second light incidence angle range that is larger than the first light incidence angle range. Incident angle dependence is defined as the degree of change in reflectance (reflectance within a specified incident wavelength range) with respect to changes in light incidence angle. For example, low incidence angle dependence indicates a small degree of change in reflectance.

The present invention also provides a lens unit having the above-mentioned film-coated lens, and a camera module having this lens unit. Such lens units and camera modules can also achieve the same effects as the above-mentioned film-coated lens.

According to the present invention, the anti-reflection film is composed of a first anti-reflection film portion on the radially inner side and a second anti-reflection film portion on the radially outer side, which have different anti-reflection properties. The anti-reflection properties of the second anti-reflection film portion are set so that at a predetermined first light incident angle, the reflectance is higher than that of the first anti-reflection film portion within a specified incident wavelength range, and at a second light incident angle greater than the first light incident angle, the reflectance is lower than that of the first anti-reflection film portion within the specified incident wavelength range. This allows the desired anti-reflection properties to be achieved within the specified incident wavelength range throughout the entire radially inner and outer regions.

1 is a schematic cross-sectional view of a lens unit with a film-coated lens according to an embodiment of the present invention. 2 is a cross-sectional view showing a state in which an anti-reflection film is formed on a coated lens that constitutes a lens group of the lens unit of FIG. 1. FIG. FIG. 2 is a schematic cross-sectional view of a camera module including the lens unit of FIG. 1 . FIG. 3 is a table showing detailed data of the laminated structure of the anti-reflection film formed on the coated lens of FIG. 2 . 5 is a diagram showing the spectral characteristics of the first and second antireflection film portions that form the laminated structure of FIG. 4 when the light incident angle is 0°. FIG. 5 is a diagram showing the spectral characteristics of the first and second antireflection film portions that form the laminated structure of FIG. 4 when the light incident angle is 45°. FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, desired anti-reflection properties can be obtained within a specified incident wavelength range over the entire inner and outer radial regions, and this contributes to "9. Build resilient infrastructure, promote inclusive and sustainable industrialization, promote innovation and build resilient infrastructure" of the Sustainable Development Goals (SDGs) advocated by the United Nations.
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 exterior surface of a vehicle, with wiring leading into the vehicle and connected to a display or other device. Hatching of the lens is omitted in Figures 1 to 3.

Figure 1 shows a lens unit 11 according to one embodiment of the present invention. As shown, the lens unit 11 of this embodiment includes a cylindrical lens barrel 12, made of, for example, resin, and multiple lenses arranged within a stepped inner storage space S of the lens barrel 12, for example, five lenses consisting of, from the object side, a first lens 13, a second lens 14, a third lens 15, a fourth lens 16, and a fifth lens 17. An in-vehicle camera equipped with such a lens unit 11 includes the lens unit 11, a board having an image sensor (not shown), and an installation member (not shown) for installing the board on a vehicle such as an automobile.

The multiple lenses 13, 14, 15, 16, and 17 incorporated and housed within the internal housing space S of the lens barrel 12 are stacked and arranged with their optical axes aligned, and the lenses 13, 14, 15, 16, and 17 are arranged along a single optical axis O to form a group of lenses L used for imaging. In this case, the first lens 13, which is positioned closest to the object and comprises the lens group L, is a spherical glass lens with a convex surface facing the object side and a concave surface facing the image side, and the other lenses 14, 15, 16, and 17 are resin lenses, but are not limited to this. The lens barrel 12 may also be made of metal.

Furthermore, the present invention, including this embodiment, is characterized by a coated lens formed with an anti-reflection coating, and the number of lenses, the materials of the lenses and lens barrel, etc. can be set arbitrarily depending on the application, etc. Also, in this embodiment, the two fourth and fifth lenses 16 and 17 positioned on the image side are cemented lenses, but this does not have to be the case.

In addition, in this embodiment, an O-ring 26 serving as a seal is interposed between the first lens 13, which is positioned closest to the object, and the lens barrel 12 to prevent water and dust from entering the lens group L inside the lens barrel 12. In this case, a stepped reduced-diameter portion 13b, whose diameter is reduced at the image-side portion of the lens 13, is provided on the outer peripheral surface 13a of the first lens 13. An O-ring 26 is attached to this reduced-diameter portion 13b, and the O-ring 26 is compressed radially between the outer peripheral surface 13a of the first lens 13 and the inner peripheral surface 12c of the lens barrel 12, thereby sealing the object-side end of the lens barrel 12. Note that the seal interposed between the first lens 13 and the lens barrel 12 is not limited to an O-ring; any form of annular body capable of sealing between the first lens 13 and the lens barrel 12 may be used.

A cylindrical inner wall 12b is provided on the object side of the lens barrel 12. A groove 18 is formed between this inner wall 12b and the outer wall 12a. A ring-shaped body 27 is provided within the groove 18, and an O-ring 26 is in close contact with this ring-shaped body 27. The groove 18 is formed between the inner wall 12b and the outer wall 12a to prevent large sink marks and dimensional inaccuracies from occurring during molding and cooling of the resin lens barrel 12, which would otherwise be caused by the thick wall if the inner wall 12b and the outer wall 12a were integrated without a groove. The ring-shaped body 27 is made of a relatively soft, elastic material, such as Teflon. The ring-shaped body 27 functions to support the O-ring 26 in the optical axis direction. Because the ring-shaped body 27 is a separate component from the lens barrel 12, it can be changed to a ring-shaped body 27 of a different height depending on the size of the O-ring 26, ensuring that the O-ring 26 provides a seal with appropriate elasticity.

In addition, with the lens group L assembled and housed within the internal housing space S of the lens barrel 12, the crimping portion 23 at the object-side end (upper end in Figure 1) is thermally crimped radially inward, thereby fixing the first lens 13, which is positioned closest to the object in the lens group L, to the object-side end of the lens barrel 12 in the optical axis direction by this crimping portion 23. In this case, to ensure stable crimping, the portion of the glass lens 13 where the crimping portion 23 is pressed against is formed as a flat portion 13c, cut diagonally in a plane.

In addition, an inner flange portion 24 is provided at the image-side end (lower end in Figure 1) of the lens barrel 12, with an opening whose diameter is smaller than that of the fifth lens 17. This inner flange portion 24 and the crimped portion 23 hold and fix the multiple lenses 13, 14, 15, 16, and 17 that make up the lens group L within the lens barrel 12 in the optical axis direction.

The inner diameter of the lens barrel 12 gradually decreases from the object side to the image plane side. Correspondingly, the outer diameters of the lenses 13, 14, 15, 16, and 17 gradually decrease from the object side to the image plane side. Basically, the outer diameters of the lenses 13, 14, 15, 16, and 17 are approximately equal to the inner diameters of the portions of the lens barrel 12 where the lenses 13, 14, 15, 16, and 17 are supported. Furthermore, an outer flange 25 is provided on the outer peripheral surface of the lens barrel 12 in the shape of a brim, and is used when installing the lens barrel 12 in an in-vehicle camera.

In this embodiment, at least one of the lenses 13, 14, 15, 16, and 17 that make up the lens group L is configured as a coated lens having an anti-reflection coating on its surface. Below, we will explain in detail the coating configuration of the second lens 14, which is a coated lens having an anti-reflection coating formed on its surface, but it goes without saying that a similar coating configuration can be applied to the other lenses 13, 15, 16, and 17. For simplicity, the anti-reflection coatings formed on the other lenses 13, 15, 16, and 17 are not shown in Figures 1 and 3.

As clearly shown in the enlarged view in Figure 2, the second lens 14 (made of resin in this embodiment, but may also be made of glass) has an object-facing surface 14a consisting of a radially inner central surface 14aa that is slightly spherically concave toward the image side and an annular outer peripheral surface 14ab that extends (extends aspherically) outward in a substantially radial direction from the outer peripheral edge of this central surface 14aa, and an image-facing surface 14b consisting of a radially inner central surface 14ba that is spherically concave toward the object side (concave with a greater curvature than central surface 14aa) and an annular outer peripheral surface 14bb that extends (extends) outward in a substantially radial direction from the outer peripheral edge of this central surface 14aa.

On the object-side surface 14a of the second lens 14, an anti-reflection coating 40 (which may be the same as the first anti-reflection coating portion 40A described below) is formed, for example, by vapor deposition, over the entire central surface 14aa and the radially inner region of the outer peripheral surface 14ab. Meanwhile, on the image-side surface 14b of the second lens 14, an anti-reflection coating 40' is also formed, for example, by vapor deposition. In this case, the anti-reflection coating 40' is composed of a first anti-reflection coating portion 40A on the radially inner side and a second anti-reflection coating portion 40B on the radially outer side, which have different anti-reflection properties. Specifically, within the effective diameter of the second lens 14, the first anti-reflection film portion 40A is formed as a multilayer structure over almost the entire area except for a portion of the radially outer region of the central surface 14ba, while the second anti-reflection film portion 40B is formed as a multilayer structure from the radially outer region of the central surface 14ba to the radially inner region of the outer surface 14bb so as not to overlap with the first anti-reflection film portion 40A. Here, the second anti-reflection film portion 40B has anti-reflection properties in which, at a predetermined first light incident angle, it has a higher reflectance than the first anti-reflection film portion 40A within a specified incident wavelength range, and, at a second light incident angle greater than the first light incident angle, it has a lower reflectance than the first anti-reflection film portion 40A within the specified incident wavelength range.

An example of the film layer configuration (film stack structure) of the first and second anti-reflection film portions 40A, 40B for achieving such anti-reflection characteristics is shown in Fig. 4. As shown in the figure, the first anti-reflection film portion 40A is formed on the material (e.g., ZEONEX (registered trademark) F52R having a refractive index of 1.54) that forms the second lens 14, and has a stack structure (here, a six-layer structure; from bottom to top, the thicknesses are 6.75 nm (ZrO2), 14.28 nm (SiO2 ₎ , 33.76 nm (ZrO2 ₎ , 9.52 nm ( _SiO2 ), 76.30 nm ( _ZrO2 ), and 85.69 nm ( _{SiO2 )} ) in which ZrO2 having a refractive index of 2.00 and _SiO2 having a refractive index of 1.42 are alternately stacked on top of a bottom SiO layer having a thickness of 26.33 nm and a refractive index of _1.54 . On the other hand, the second anti-reflection film portion 40B is formed on the material forming the second lens 14 (for example, ZEONEX (registered trademark) F52R having a refractive index of 1.54), and has a layered structure (here, a six-layer structure; from bottom to top, the thicknesses are 13.44 nm (ZrO 2 ), 51.68 nm (SiO _{2 )} , 48.07 nm (ZrO 2 ), 17.62 nm (SiO ₂ ), 85.27 nm (ZrO 2 ), and 112.93 nm (SiO ₂ )) in which ZrO ₂ having a refractive index of 2.00 and SiO ₂ having a refractive index of 1.42 are alternately layered on top of a bottom SiO layer having a thickness of 34.59 _nm and a refractive _index of _1.54 . As can be seen from these layered structures, the film thickness of the second antireflection film portion 40B (total film thickness 363.60 nm) is clearly greater than the film thickness of the first antireflection film portion 40A (total film thickness 252.63 nm). The first and second antireflection film portions 40A, 40B are formed, for example, by first masking the radially outer region of the image-side surface 14b of the lens 14 (the region where the second antireflection film portion 40B is to be formed) and forming the first antireflection film portion 40A by vapor deposition, and then masking the radially inner region of the surface 14b (the region where the first antireflection film portion 40A is formed) and forming the second antireflection film portion 40B by vapor deposition.

When this film stack structure of the first and second anti-reflection film sections 40A and 40B was optimized by a predetermined simulation at a predetermined light incidence angle, the spectral characteristic curves shown in the spectral characteristic diagrams of Figures 5 and 6 (spectral characteristic diagrams showing the relationship between the reflectance (%) of the anti-reflection film and the wavelength (nm) of incident light) were obtained (spectral characteristic curve L1 represents the first anti-reflection film section 40A, and spectral characteristic curve L2 represents the second anti-reflection film section 40B). Specifically, Figure 5 shows the case where optimization was performed by a predetermined simulation at a light incidence angle of 0°, while Figure 6 shows the case where optimization was performed by a predetermined simulation at a light incidence angle of 45°. 5, at the small first light incident angle of 0°, the second anti-reflection coating portion 40B (spectral characteristic curve L2) has a higher reflectance than the first anti-reflection coating portion 40A (spectral characteristic curve L1) within a specified incident wavelength range, in this case, at least within the incident wavelength range of 450 nm to 600 nm or more. In other words, the first anti-reflection coating portion 40A has a lower reflectance than the second anti-reflection coating portion 40B within the incident wavelength range of 450 nm to 600 nm or more. That is, the reflectance of the first anti-reflection coating portion 40A is lower than the reflectance of the second anti-reflection coating portion 40B within the incident wavelength range of 450 nm to 600 nm or more. Of course, the specified incident wavelength range that satisfies these anti-reflection properties can be varied by adjusting the film layer configuration and the thickness of each layer, but at a light incident angle of 0°, it is preferable that the reflectance of the first anti-reflection film portion 40A be lower than the reflectance of the second anti-reflection film portion 40B, at least within the incident wavelength range of 450 nm to 650 nm.

On the other hand, as can be seen from Figure 6, at the larger second light incident angle of 45°, the second anti-reflection coating portion 40B (spectral characteristic curve L2) has a lower reflectance than the first anti-reflection coating portion 40A (spectral characteristic curve L1) within the specified incident wavelength range, in this case, within the incident wavelength range of 450 nm or more (exhibiting characteristics such as maintaining a minimum reflectance over a wide wavelength range (approximately 450 nm to approximately 650 nm in the figure)). In other words, the first anti-reflection coating portion 40A has a higher reflectance than the second anti-reflection coating portion 40B within the incident wavelength range of 450 nm or more. That is, within the incident wavelength range of 450 nm or more, the reflectance of the second anti-reflection coating portion 40B is lower than the reflectance of the first anti-reflection coating portion 40A. In this case, as before, the specified incident wavelength range that satisfies these anti-reflection properties can be varied by adjusting the film layer configuration and the thickness of each layer, but at a light incident angle of 45°, it is preferable that the reflectance of the second anti-reflection film portion 40B be lower than the reflectance of the first anti-reflection film portion 40A, at least within the incident wavelength range of 450 nm to 650 nm.

Note that while the light incidence angles shown here are 0° and 45°, it is preferable that the above anti-reflection characteristics be satisfied for other light incidence angle relationships. Furthermore, in this embodiment, in addition to the above, it is preferable that the first anti-reflection film portion 40A has lower incidence angle dependency than the second anti-reflection film portion 40B within a predetermined first light incidence angle range, and it is also preferable that the second anti-reflection film portion 40B has lower incidence angle dependency than the first anti-reflection film portion 40A within a second light incidence angle range that is larger than the first incident angle range.

Also, Figure 3 is a schematic cross-sectional view of a camera module 300 of this embodiment that has the lens unit 11 of Figure 1. As shown in the figure, the camera module 300 is configured to include the lens unit 11 to which the filter 100 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 (image sensor) 304 as an imaging element.

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 sealing member 303 is a member that is interposed between the inner surface of the upper case 301 and the outer peripheral surface 12d 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 located inside the mount 302 and is positioned to receive the image of the object formed by the lens unit 11. The package sensor 304 is equipped with a CCD, CMOS, or other device, and converts the light that is collected and reaches it through the lens unit 11 into an electrical signal. The converted electrical signal is then converted into analog data or digital data, which are components of the image data captured by the camera.

As described above, in the coated lens 14 of this embodiment, the anti-reflection coating 40' is composed of a first anti-reflection coating portion 40A on the radially inner side and a second anti-reflection coating portion 40B on the radially outer side, which have different anti-reflection properties. The anti-reflection properties of the second anti-reflection coating portion 40B are set so that it has a higher reflectance than the first anti-reflection coating portion 40A within a specified incident wavelength range at a predetermined first light incident angle, and a lower reflectance than the first anti-reflection coating portion 40A within a specified incident wavelength range at a second light incident angle larger than the first light incident angle. This allows the desired anti-reflection properties to be maintained within the specified incident wavelength range throughout the entire radially inner and outer regions.

While one embodiment of the present invention has been described above, the present invention can be modified in various ways without departing from the spirit of the invention. For example, the shapes of the lenses, lens barrels, etc. in the present invention are not limited to those in the embodiment described above. Furthermore, the anti-reflection coating on the lens may take any form as long as it has the function described above. Furthermore, some or all of the embodiments described above may be combined, or part of the configuration may be omitted from one of the embodiments described above, without departing from the spirit of the present invention.

11 Lens unit 12 Lens barrel 14 Lens (lens with film)
14ba: central surface; 14bb: outer peripheral surface; 40, 40': anti-reflection coating; 40A: first anti-reflection coating portion; 40B: second anti-reflection coating portion; 300: camera module; L: lens group;

Claims (8)

A film-coated lens provided in a lens barrel and having an anti-reflection film formed on its surface,
a surface facing the image side that is a combination of a radially inner central surface that is spherically recessed toward the object side and an annular outer peripheral surface that extends outward in a substantially radial direction from an outer peripheral edge of the central surface,
the anti-reflection film has a first anti-reflection film portion on the inner side in the radial direction and a second anti-reflection film portion on the outer side in the radial direction, the first anti-reflection film portion having different anti-reflection properties from the second anti-reflection film portion,
Within the lens effective diameter, the first anti-reflection film portion is formed in a multilayer structure over the entire area except for a portion of the radially outer area of the central surface, and the second anti-reflection film portion is formed in a multilayer structure separate from the first anti-reflection film portion over the area from the radially outer area of the central surface to the radially inner area of the outer peripheral surface so as not to overlap with the first anti-reflection film portion , thereby dividing the anti-reflection film into an inner area and an outer area in the radial direction,
a first anti-reflection film portion having a thickness greater than that of the first anti-reflection film portion within a specified incident wavelength range at a predetermined first light incident angle, and a second anti-reflection film portion having a thickness greater than that of the first anti-reflection film portion within a specified incident wavelength range at a second light incident angle greater than the first light incident angle, the second anti-reflection film portion having a thickness greater than that of the first anti-reflection film portion within a specified incident wavelength range at a predetermined first light incident angle, and a thickness greater than that of the first anti-reflection film portion within a specified incident wavelength range at a second light incident angle greater than the first light incident angle, the second anti-reflection film portion having a thickness greater than that of the first anti-reflection film portion within a specified incident wavelength range at a predetermined ... The lens with a film as described in claim 1 further has a surface facing the object side which is a combination of a radially inner central surface which is spherically concave toward the image side and an annular outer peripheral surface which extends aspherically from the outer peripheral edge of this central surface to the outside in an approximately radial direction, and the first anti-reflection film portion is formed on this surface facing the object side over the entire central surface and the radially inner region of the outer peripheral surface. A lens with a film according to claim 2, characterized in that the central surface of the surface facing the image side is concave with a greater curvature than the central surface of the surface facing the object side. The coated lens described in claim 1, characterized in that the thickness of the second anti-reflection coating portion is greater than the thickness of the first anti-reflection coating portion. A lens with a film described in any one of claims 1 to 4, characterized in that the specified incident wavelength range is 450 nm to 650 nm. A lens with a film according to any one of claims 1 to 5, characterized in that the first light incident angle is 0° and the second light incident angle is 45°. A lens unit comprising a lens group in which a plurality of lenses are arranged along the optical axis of the lenses, and a lens barrel in which the lens group is housed,
A lens unit, wherein at least one of the lenses constituting the lens group is the film-coated lens according to any one of claims 1 to 6. A camera module comprising the lens unit described in claim 7.