WO2021015131A1

WO2021015131A1 - Light-shielding plate, camera unit, and electronic device

Info

Publication number: WO2021015131A1
Application number: PCT/JP2020/027893
Authority: WO
Inventors: 清明西辻; 槙一島村
Original assignee: 凸版印刷株式会社
Priority date: 2019-07-19
Filing date: 2020-07-17
Publication date: 2021-01-28
Also published as: WO2021015132A1; WO2021015130A1

Abstract

The present invention comprises an obverse surface positioned on a side at which light impinges, a reverse surface that is on the side opposite from the obverse surface, and a hole passing through between the obverse surface and the reverse surface. The hole comprises a first hole portion and a second hole portion that is connected to the first hole portion at a central opening. The first hole portion extends from a reverse-surface opening in the reverse surface to the central opening, and has a shape that tapers from the reverse surface toward the obverse surface. The second hole portion extends from an obverse-surface opening in the obverse surface to the central opening, and has a shape that tapers from the obverse surface toward the reverse surface. The size of the obverse-surface opening is greater than that of the reverse-surface opening. When an edge of the central opening is imaged along the radial direction of the central opening in a state in which a focal point overlaps the edge of the central opening under imaging conditions such that the depth of field is 0.4 µm, the maximum width of a light-shielding plate overlapped by the focal point in the thickness direction of the light-shielding plate is 7.0 µm or less.

Description

Shading plate, camera unit, and electronic devices

The present invention relates to a light-shielding plate, a camera unit including a light-shielding plate, and an electronic device including the camera unit.

The camera unit of electronic devices such as smartphones is equipped with a light-shielding plate that functions as an aperture for external light. Since a light-shielding plate having a predetermined shape can be easily molded, a resin-made light-shielding plate is often used (see, for example, Patent Document 1). However, since the light-shielding plate made of resin has light transmittance, it allows external light to pass not only through the holes for passing external light but also in the portion that partitions the holes. As described above, since the light shielding by the resin light-shielding plate is not sufficient, a metal light-shielding plate having a higher light-shielding property has begun to be used (see, for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 2010-8786 International Publication No. 2016/060198

By the way, since the difficulty of processing is low and it is possible to manufacture many products per unit time, when manufacturing a metal light-shielding plate, the punching process of punching the metal plate with a die is performed. It is used. In the processing of a metal plate using punching, the surface of the metal plate is prevented from being deformed or distorted when the metal plate is punched by a die, thereby ensuring accuracy in the dimensions of the product. It is required to punch a metal plate along a direction orthogonal to. As a result, the metal plate is formed with a hole having a side surface extending perpendicularly to the surface of the metal plate in a cross section orthogonal to the surface of the metal plate.

When a light-shielding plate having such holes is mounted on the camera unit, external light incident on the light-shielding plate from the direction of forming an acute angle with the surface of the light-shielding plate is reflected on the side surface that partitions the holes, and as a result. It may pass through the hole. The light that has passed through the hole is received by the imaging unit included in the camera unit, and at least one of ghost and flare may occur in the image captured by the imaging unit. As described above, the metal light-shielding plate has a new problem because the light-shielding plate is made of metal.

An object of the present invention is to provide a shading plate, a camera unit, and an electronic device capable of reducing the amount of light reflected by a side surface that partitions a hole so as to pass through the hole.

The light-shielding plate for solving the above-mentioned problems is a metal light-shielding plate, which is a front surface located on the incident side of light, a back surface which is a surface opposite to the front surface, and the front surface and the back surface. It is provided with a hole penetrating between them. The hole includes a first hole portion and a second hole portion connected to the first hole portion at the central opening, and the first hole portion extends from the back surface opening on the back surface to the central opening. The second hole portion has a shape that tapers from the back surface toward the front surface, extends from the surface opening on the front surface to the central opening, and has a shape that tapers from the front surface toward the back surface. The size of the front surface opening is larger than the size of the back surface opening. Under imaging conditions where the depth of field is 0.4 μm, when the edge of the central aperture is imaged along the radial direction of the central aperture with the edge of the central aperture in focus, the focus is achieved. The maximum width of the light-shielding plate in the thickness direction of the light-shielding plate is 7.0 μm or less.

The camera unit for solving the above problems includes the above-mentioned light-shielding plate.
An electronic device for solving the above problems includes the above camera unit.

According to each of the above configurations, the maximum width of the light-shielding plate to be focused is 7.0 μm or less, so that the area of the side surface that partitions the hole in the vicinity of the central opening is reduced, whereby the hole is formed in the vicinity of the central opening. It is possible to reduce the amount of light reflected on the side surface of the partition. As a result, the amount of light reflected by the side surface that partitions the hole so as to pass through the hole can be reduced.

The light-shielding plate for solving the above-mentioned problems is a metal light-shielding plate, which is a front surface located on the incident side of light, a back surface which is a surface opposite to the front surface, and the front surface and the back surface. It is provided with a hole penetrating between them. The hole includes a first hole portion and a second hole portion connected to the first hole portion at the central opening, and the first hole portion extends from the back surface opening on the back surface to the central opening. The second hole portion has a shape that tapers from the back surface toward the front surface, extends from the surface opening on the front surface to the central opening, and has a shape that tapers from the front surface toward the back surface. The size of the front surface opening is larger than the size of the back surface opening. Under imaging conditions where the depth of field is 0.4 μm, when the edge of the central aperture is imaged along the radial direction of the central aperture with the edge of the central aperture in focus, the focus is achieved. The maximum width of the light-shielding plate in the thickness direction of the light-shielding plate is 30% or less of the thickness of the light-shielding plate.

According to the above configuration, the maximum width of the light-shielding plate in focus is 30% or less of the thickness of the light-shielding plate, so that the area of the side surface that partitions the hole in the vicinity of the central opening is reduced, thereby reducing the central opening. It is possible to reduce the amount of light reflected on the side surface that partitions the hole in the vicinity of. As a result, the amount of light reflected by the side surface that partitions the hole so as to pass through the hole can be reduced.

The plan view which shows the structure of the light-shielding plate in 1st Embodiment. FIG. 5 is a cross-sectional view showing the structure of the light shielding plate shown in FIG. A partially enlarged cross-sectional view showing a part of the cross-sectional view shown in FIG. 2 in an enlarged manner. The operation diagram for demonstrating the operation of the light-shielding plate of 1st Embodiment. The operation diagram for demonstrating the operation of the light-shielding plate of 1st Embodiment. The process drawing for demonstrating the manufacturing method of the light-shielding plate of 1st Embodiment. The process drawing for demonstrating the manufacturing method of the light-shielding plate of 1st Embodiment. The process drawing for demonstrating the manufacturing method of the light-shielding plate of 1st Embodiment. The process drawing for demonstrating the manufacturing method of the light-shielding plate of 1st Embodiment. A partially enlarged cross-sectional view showing a part of the cross-sectional view of the light-shielding plate according to the second embodiment. An image of the cross-sectional structure of the light-shielding plate of Example 2-1. A partially enlarged cross-sectional view showing a part of the cross-sectional view of the light-shielding plate according to the third embodiment. An image of the cross-sectional structure of the light-shielding plate of Example 3-1.

[First Embodiment]
A first embodiment of a shading plate, a camera unit, and an electronic device will be described with reference to FIGS. 1 to 9. Hereinafter, a light-shielding plate, a method for manufacturing the light-shielding plate, and an embodiment will be described in order.

[Shading plate]
The light-shielding plate will be described with reference to FIGS. 1 to 5.
As shown in FIG. 1, the metal shading plate 10 includes a front surface 10F, a back surface 10R, and a hole 10H. The surface 10F is a surface located on the incident side of light. The back surface 10R is a surface opposite to the front surface 10F. The hole 10H penetrates between the front surface 10F and the back surface 10R. The light-shielding plate 10 is made of stainless steel, for example, but may be made of a metal other than stainless steel. In the light-shielding plate 10, the front surface 10F, the back surface 10R, and the side surface for partitioning the hole 10H are covered with an antireflection film (not shown). The antireflection film has a lower reflectance than the metal forming the light-shielding plate 10, and has a function of absorbing a part of the light irradiated to the antireflection film. Further, even if the light-shielding plate 10 is covered with an antireflection film, the reflection of light on the light-shielding plate 10 cannot be completely eliminated.

The light-shielding plate 10 has a circular shape corresponding to the shape of the lens covered by the light-shielding plate 10. The hole 10H has a circular shape corresponding to the shape of the lens with which the hole 10H faces.

FIG. 2 shows the structure of the light-shielding plate 10 in a cross section orthogonal to the surface 10F of the light-shielding plate 10.
As shown in FIG. 2, the hole 10H includes a first hole portion 10H1 and a second hole portion 10H2. The first hole portion 10H1 extends from the back surface opening H1R on the back surface 10R to the central opening HC (see FIG. 3). The first hole portion 10H1 has a shape that tapers from the back surface 10R toward the front surface 10F. The second hole portion 10H2 extends from the surface opening H2F on the surface 10F to the central opening HC. The second hole portion 10H2 has a shape that tapers from the front surface 10F to the back surface 10R. The size of the front opening H2F is larger than the size of the back opening H1R. The second hole portion 10H2 is connected to the first hole portion 10H1 in the central opening HC. That is, the central opening HC is located on the way from the front surface 10F to the back surface 10R in the thickness direction of the light-shielding plate 10.

In the present embodiment, in a cross section along a plane orthogonal to the surface 10F, the side surface for partitioning the second hole portion 10H2 is arcuate, and the center of curvature of the side surface for partitioning the second hole portion 10H2 is the light-shielding plate 10. Located outside. Further, in a cross section along a plane orthogonal to the surface 10F, the side surface for partitioning the first hole portion 10H1 is arcuate, and the center of curvature of the side surface for partitioning the first hole portion 10H1 is located outside the shading plate 10. There is.

In the light shielding plate 10, the diameter of the first hole portion 10H1 is the first diameter DH1, and the diameter of the second hole portion 10H2 is the second diameter DH2. The first diameter DH1 is set according to the camera unit on which the shading plate 10 is mounted. The first diameter DH1 may be 0.4 mm or more and 1.0 mm or less when the light-shielding plate 10 is mounted on a camera unit of a smartphone, for example. Further, the first diameter DH1 may be 2.0 mm or more and 7.0 mm or less when the light-shielding plate 10 is mounted on, for example, an in-vehicle camera.

The percentage (DH1 / DH2 × 100) of the first diameter DH1 with respect to the second diameter DH2 may be, for example, 80% or more and 99% or less. When the shading plate 10 is mounted on a smartphone, a tablet-type personal computer, or a camera unit installed in front of a notebook-type personal computer, the camera unit often shoots a subject at a short distance. Therefore, although the angle of view is large, the light-shielding plate 10 does not require a large inner diameter for the lens to focus on the subject. Further, it is difficult to increase the outer diameter of the light-shielding plate 10 due to the limitation of the space in which the camera unit is arranged. Therefore, the percentage of the first diameter DH1 with respect to the second diameter DH2 may be 80% or more and 90% or less.

On the other hand, when the shading plate 10 is mounted on the in-vehicle camera, the in-vehicle camera often shoots the subject from a medium distance to a long distance. Therefore, although the angle of view is small, the limitation of the space in which the camera unit is arranged is small, so that the diameter of the lens provided in the camera unit is large. Thereby, in order to collect light in a wide range with respect to the lens, the ratio of the first diameter DH1 to the second diameter DH2 in the light shielding plate 10 may be 90% or more and 99% or less.

Further, when the shading plate 10 is mounted on a camera unit installed on the back of a smartphone, the camera unit often shoots a subject from a short distance to a long distance. Therefore, the ratio of the first diameter DH1 to the second diameter DH2 may be 80% or more and 90% or less in dealing with the case where the angle of view becomes large, and in dealing with the case where the angle of view becomes small. The ratio of the first diameter DH1 to the second diameter DH2 may be 90% or more and 99% or less.

The thickness T of the light-shielding plate 10 may be, for example, 10 μm or more and 100 μm or less. When the thickness T of the light-shielding plate 10 is 10 μm or more, it is possible to prevent the warp of the metal foil for forming the light-shielding plate 10 from affecting the shape of the light-shielding plate 10. Further, when the thickness T of the light-shielding plate 10 is 100 μm or less, it is possible to suppress a decrease in etching accuracy when forming the holes 10H.

FIG. 3 shows an enlarged part of the cross-sectional structure of the light-shielding plate 10 shown in FIG.
As shown in FIG. 3, the back surface 10R of the light-shielding plate 10 partitions the back surface opening H1R, and the first hole portion 10H1 is connected to the second hole portion 10H2 in the central opening HC. In the thickness direction of the light-shielding plate 10, the distance between the back surface 10R and the edge of the central opening HC is the first distance D11. The distance between the surface 10F and the edge of the central opening HC in the thickness direction of the light-shielding plate 10 is the second distance D12. In the light-shielding plate 10, the ratio (D12 / D11) of the second distance D12 to the first distance D11 is 2.5 or more.

As the ratio of the second distance D12 to the first distance D11 (D12 / D11) increases, the central opening HC relatively approaches the back opening H1R. As a result, the area on the side surface of the first hole portion 10H1 can be reduced. Therefore, a part of the light incident on the hole 10H from diagonally above the light-shielding plate 10 is reflected on the surface of the lens and then incident on the first hole portion 10H1 to enter the lens LN from the first hole portion 10H1 (FIG. 4). Reflection towards (see) is suppressed.

The ratio of the second distance D12 to the first distance D11 (D12 / D11) preferably approaches infinity. However, in reality, in the etching for forming the holes 10H, the etching solution soaks into the gap between the metal foil for forming the light-shielding plate 10 and the mask formed on the metal foil, and thereby, about submicrons. A first hole portion 10H1 having a depth of, i.e., a first distance D11 is formed. Therefore, for example, when the metal foil has a thickness of 100 μm, the lower limit of the first distance D11 is about 0.1 μm. Therefore, the upper limit of the ratio (D12 / D11) of the second distance D12 to the first distance D11 is about 1000.

The surface opening H2F has a circular shape when viewed from the viewpoint facing the surface 10F. The side surface that partitions the second hole portion 10H2 when viewed from the viewpoint facing the surface 10F is divided into five equal parts in the radial direction of the surface opening H2F by a surface concentric with respect to the center of the surface opening H2F. In this case, when viewed from the viewpoint facing the surface 10F, the side surfaces that partition the second hole portion 10H2 are the first regions R1 and the second along the direction from the edge of the surface opening H2F to the edge of the central opening HC. It has a region R2, a third region R3, a fourth region R4, and a fifth region R5. The first region R1 is a region including the edge of the surface opening H2F among the side surfaces for partitioning the second hole portion 10H2. The fifth region R5 is a region including the edge of the central opening HC among the side surfaces for partitioning the second hole portion 10H2.

In the cross section along the plane orthogonal to the surface 10F, that is, the cross section along the plane passing through the center described above, in each region, one end and the other end of a part of the side surface partitioning the second hole portion 10H2 with respect to the surface 10F are connected. The straight line, that is, the inclination of the line segment, is the inclination angle at the portion included in each region in the side surface. In the first region R1, the angle formed by the first straight line L11 and the surface 10F is the first inclination angle θ11, and in the second region R2, the angle formed by the second straight line L12 and the surface 10F is the second inclination angle. It is θ12. In the third region R3, the angle formed by the third straight line L13 and the surface 10F is the third inclination angle θ13, and in the fourth region R4, the angle formed by the fourth straight line L14 and the surface 10F is the fourth inclination angle. It is θ14, and the angle formed by the fifth straight line L15 and the surface 10F in the fifth region R5 is the fifth inclination angle θ15.

In the cross section along the plane orthogonal to the surface 10F, the first inclination angle θ11 of the first region R1 is larger than the inclination angle in the other regions among the side surfaces that partition the second hole portion 10H2. That is, the first inclination angle θ11 of the first region R1 among the five regions has the maximum size. The first inclination angle θ11 is larger than each of the second inclination angle θ12, the third inclination angle θ13, the fourth inclination angle θ14, and the fifth inclination angle θ15. The first inclination angle θ11 is 50 ° or more and 60 ° or less.

In the cross section along the plane orthogonal to the surface 10F, the fifth inclination angle θ15 of the fifth region R5 is larger than the fourth inclination angle θ14 among the side surfaces that partition the second hole portion 10H2. Further, from the first region R1 to the fourth region R4, the inclination angle in the portion included in each region among the side surfaces for partitioning the second hole portion 10H2 becomes smaller. That is, on the side surface that partitions the second hole portion 10H2, the inclination angle becomes smaller in the order of the first inclination angle θ11, the second inclination angle θ12, the third inclination angle θ13, and the fourth inclination angle θ14.

FIG. 4 shows the cross-sectional structure of the light-shielding plate 10 in this embodiment. On the other hand, FIG. 5 shows a cross-sectional structure in an example in which the side surface for partitioning the hole extends along the direction orthogonal to the surface in the cross section orthogonal to the surface. In FIGS. 4 and 5, for convenience of illustration, the first diameter with respect to the thickness of the light-shielding plate is reduced.

As shown in FIG. 4, light incident on the light-shielding plate 10 from a direction orthogonal to the surface 10F enters the hole 10H through the surface opening H2F formed on the surface 10F. Then, the light that has passed through the hole 10H reaches the lens LN by exiting from the back surface opening H1R formed on the back surface 10R. On the other hand, in the light-shielding plate 10, since the second hole portion 10H2 has a shape that tapers from the front surface 10F toward the back surface 10R, the light incident on the hole 10H from diagonally above the front surface 10F partitions the second hole portion 10H2. It is easy to be reflected toward the surface 10F of the light-shielding plate 10 on the side surface.

Moreover, since the ratio (D11 / D12) of the first distance D11 between the front surface 10F and the central opening HC to the second distance D12 between the back surface 10R and the central opening HC is 2.5 or more, the second. It is possible to maintain the size of the hole portion 10H2 to a size that can be tapered from the front surface 10F to the back surface 10R. This makes it possible to reduce the amount of light reflected on the side surface that partitions the hole 10H so as to pass through the hole 10H. As a result, it is possible to prevent unintended light from entering the lens LN facing the light-shielding plate 10.

In the present embodiment, the first inclination angle θ11 in the first region R1 is larger than the inclination angle in each of the second region R2 to the fifth region R5. Therefore, it is possible to prevent the diameter of the second hole portion 10H2 from becoming excessively large, and to make it easier for light to be reflected toward the surface 10F of the light-shielding plate 10 in a region other than the first region R1. Since the first inclination angle θ11 is 50 ° or more and 60 ° or less, in the first region R1 including the surface opening H2F among the side surfaces for partitioning the second hole portion 10H2, toward the surface 10F of the light shielding plate 10. The certainty of reflecting light can be increased.

In the present embodiment, the fifth inclination angle θ15 of the fifth region R5 is larger than the fourth inclination angle θ14 of the fourth region R4, so that the fifth inclination angle θ15 of the fifth region R5 is the fourth of the fourth region R4. 4 It is possible to suppress the expansion of the diameter of the second hole portion 10H2 as compared with the case where it is smaller than the inclination angle θ14. Further, since the inclination angle in each region becomes smaller from the first region R1 to the fourth region R4, the inclination of the side surface for partitioning the second hole portion 10H2 is the same from the first region R1 to the fourth region R4. The closer to the central opening HC, the easier it is for the light incident on the second hole portion 10H2 to be reflected toward the surface 10F of the light-shielding plate 10.

Further, the light incident on the second hole portion 10H2 from diagonally above the surface 10F is reflected on the side surface having an arc shape such that the center of curvature is located outside the light shielding plate 10. Therefore, the specularly reflected light having the highest brightness among the reflected light is reflected along the direction from the arc-shaped side surface toward the surface 10F of the light-shielding plate 10. Therefore, the amount of light reflected by the side surface that partitions the hole 10H so as to pass through the hole 10H is further suppressed.

In the light-shielding plate 10, the side surface that partitions the first hole portion 10H1 has an arc shape such that the center of curvature is located outside the light-shielding plate 10. Therefore, as compared with the case where the side surface for partitioning the first hole portion 10H1 has a linear shape, the light incident on the hole from diagonally above the front surface 10F is reflected by the side surface for partitioning the hole 10H in the vicinity of the back surface opening H1R. The amount of light produced can be reduced. As a result, the amount of light reflected on the side surface that partitions the hole 10H so as to pass through the hole can be further reduced.

As shown in FIG. 5, the light incident on the light-shielding plate 100 from the direction orthogonal to the surface 100F was formed on the surface 100F in the same manner as the light incident on the light-shielding plate 10 from the direction orthogonal to the surface 10F. Enter the hole 100H through the opening. Then, the light that has passed through the hole 100H reaches the lens LN by exiting from the opening formed in the back surface 100R. On the other hand, a part of the light incident on the surface 100F from diagonally above the surface 100F is incident on the hole 100H from the opening formed on the surface 100F and is reflected on the side surface for partitioning the hole 100H. Since most of the light incident on the side surface is reflected in the direction of specular reflection, the light incident on the side surface is reflected from the side surface toward the lens LN. As a result, unintended light enters the image pickup unit through the lens LN.

One or more of the light-shielding plates 10 described above are provided in the above-mentioned camera unit. Further, the camera unit provided with the light-shielding plate 10 is mounted on various electronic devices. The electronic device including the camera unit may be, for example, a smartphone, a tablet-type personal computer, a notebook-type personal computer, or the like.

[Manufacturing method of shading plate]
A method for manufacturing the light-shielding plate 10 will be described with reference to FIGS. 6 to 9. Each of FIGS. 6 to 9 shows the cross-sectional structure of the metal leaf in a specific step in the manufacturing process of the light-shielding plate 10. In FIGS. 6 to 9, for convenience of illustration, the ratio of the second diameter DH2 to the thickness of the metal foil is smaller than that of the actual light-shielding plate, and the ratio of the first diameter DH1 to the thickness of the metal foil is It is smaller than the actual shading plate. Further, in FIGS. 6 to 9, for convenience of illustration, the ratio of the first diameter DH1 to the second diameter DH2 is smaller than that of the actual light-shielding plate. Further, in FIGS. 6 to 9, for convenience of explanation, only the steps related to the formation of the holes 10H of the light-shielding plate 10 are shown in the steps of manufacturing the light-shielding plate 10.

As shown in FIG. 6, when forming the light-shielding plate 10, first, a metal foil 10M for forming the light-shielding plate 10 is prepared. The metal foil 10M is, for example, a stainless steel foil, but as described above, it may be a metal foil formed of a metal other than stainless steel. The thickness of the metal foil 10M is 10 μm or more and 100 μm or less. When the thickness of the metal foil 10M is 10 μm or more, it is possible to prevent the warp of the metal foil 10M from affecting the shape of the light-shielding plate 10. Further, when the thickness of the metal foil 10M is 100 μm or less, it is possible to suppress a decrease in etching accuracy when forming the holes 10H. The thickness of the metal foil 10M is substantially the same as the thickness of the light-shielding plate 10 manufactured from the metal foil 10M.

Then, a resist layer is arranged on the front surface 10MF and the back surface 10MR of the metal foil 10M. The front surface 10MF of the metal foil 10M corresponds to the front surface 10F of the light-shielding plate 10, and the back surface 10MR of the metal foil 10M corresponds to the back surface 10R of the light-shielding plate 10. The front surface resist layer RF is arranged on the front surface 10MF of the metal foil 10M, and the back surface resist layer RR is arranged on the back surface 10MR of the metal foil 10M. A dry film resist may be attached as resist layers RF and RR on both the front surface 10 MF and the back surface 10 MR. Alternatively, the resist layers RF and RR may be formed on both the front surface 10MF and the back surface 10 MR by using a coating liquid for forming the resist layers RF and RR. The resist layers RF and RR may be formed by a negative type resist or a positive type resist.

As shown in FIG. 7, a resist mask is formed from the resist layer by exposure and development of the resist layers RF and RR. More specifically, exposure and development of the surface resist layer RF forms a surface mask RMF from the surface resist layer RF. Further, the back surface mask RMR is formed from the back surface resist layer RR by exposure and development of the back surface resist layer RR. The surface mask RMF has mask holes RMFh for forming a second hole portion in the metal foil 10M. The back surface mask RMR has a mask hole RMRh for forming the first hole portion in the metal foil 10M.

As shown in FIG. 8, using the back surface mask RMR formed on the back surface 10 MR, the first hole portion MH1 having a back surface opening on the back surface 10 MR and having a shape tapering from the back surface 10 MR toward the front surface 10 MF. Is formed on the metal foil 10M. The first hole portion MH1 corresponds to the first hole portion 10H1 of the light shielding plate 10. At this time, the metal leaf 10M is etched using an etching solution capable of etching the metal leaf 10M. Before etching the metal foil 10M, the surface mask RMF is covered with a surface protective film PMF having resistance to an etching solution. The surface protective film PMF may fill or cover the mask holes RMFh of the surface mask RMF. By covering the surface mask RMF with the surface protective film PMF, it is possible to prevent the front surface 10MF of the metal foil 10M from being etched at the same time as the back surface 10MR of the metal foil 10M.

When the first hole portion MH1 is formed by etching the back surface 10MR, the first hole portion MH1 having a depth larger than the distance between the back surface 10R and the central opening HC of the light shielding plate 10 described above. Is formed.

As shown in FIG. 9, after forming the first hole portion MH1, the surface mask RMF formed on the front surface 10MF is used to have a surface opening on the front surface 10MF and taper from the front surface 10MF to the back surface 10MR. The second hole portion MH2 having the same shape is formed on the metal foil 10M so as to be connected to the first hole portion MH1. The second hole portion MH2 corresponds to the second hole portion 10H2 of the light shielding plate 10. At this time, the metal foil 10M is etched using an etching solution capable of etching the metal foil 10M, as in the case of forming the first hole portion MH1. Before etching the metal foil 10M, the back surface mask RMR is removed from the back surface 10MR of the metal foil 10M.

Further, before etching the metal foil 10M, the back surface 10MR of the metal foil 10M is covered with the back surface protective film PMR having resistance to the etching solution, and the inside of the first hole portion MH1 is filled. By covering the back surface 10MR of the metal foil 10M with the back surface protective film PMR, it is possible to prevent the back surface 10MR of the metal foil 10M from being etched at the same time as the front surface 10MF of the metal foil 10M.

In the etching of the second hole portion MH2, the surface 10MF of the metal foil 10M is etched with the first hole portion MH1 filled with the back surface protective film PMR. Therefore, after the etching of the front surface 10MF reaches the back surface protective film PMR, the supply of the etching solution to the metal foil 10M is controlled by the back surface protective film PMR. Thereby, even when the thickness of the metal foil 10M covers a wide range of 10 μm or more and 100 μm or less, the accuracy of the cross-sectional shape in the cross-sectional shape of the second hole portion MH2 can be improved. On the other hand, when the inside of the first hole portion MH1 is not filled with the back surface protective film PMR, when the metal foil 10M is penetrated by connecting the first hole portion MH1 and the second hole portion MH2, The etching solution leaks toward the back surface 10MR of the metal foil 10M through the connection portion between the first hole portion MH1 and the second hole portion MH2. As a result, the accuracy of the shape of the first hole portion MH1 and the shape of the second hole portion MH2 is lowered.

After forming the first hole portion MH1 and the second hole portion MH2, the front surface mask RMF is removed from the front surface 10 MF, and the back surface protective film PMR is removed from the back surface 10 MR. Further, after the front surface mask RMF and the back surface protective film PMR are removed from the metal foil 10M, an antireflection film covering the front surface 10MF, the back surface 10MR, and the side surface for partitioning the first hole portion MH1 and the second hole portion MH2 is formed. Will be done. As described above, the antireflection film has a reflectance lower than that of the metal foil 10M, and has a function of absorbing a part of the light incident on the antireflection film.

The antireflection film is, for example, a film having a black color. The antireflection film may be formed on the metal foil 10M by using a film forming method such as a sputtering method or a vapor deposition method. Alternatively, the antireflection film may be formed on the metal foil 10M by bringing the metal foil 10M into contact with the liquid for forming the antireflection film.

By such a method of manufacturing the light-shielding plate 10, one hole 10H is provided, and in the thickness direction of the light-shielding plate 10, the front surface 10F and the edge of the central opening HC with respect to the distance between the back surface 10R and the edge of the central opening HC A light-shielding plate 10 having a distance ratio of 2.5 or more is manufactured.

In the method for manufacturing the light-shielding plate 10 described above, it is not necessary to remove the back surface mask RMR before forming the back surface protective film PMR. In this case, the back surface mask RMR may be covered and the back surface protective film PMR may be formed in the first hole portion MH1. Further, the back surface protective film PMR may be removed from the back surface 10 MR together with the back surface mask RMR after the second hole portion MH2 is formed by etching the front surface 10 MF.

[Example]
Examples and comparative examples will be described.
[Example 1-1]
A stainless steel foil having a thickness of 30 μm was prepared. Then, after the first hole portion was formed by etching the stainless steel foil from the back surface of the stainless steel foil, the second hole portion was formed by etching the stainless steel foil from the front surface of the stainless steel foil. As a result, it has a first hole portion and a second hole portion, and has a central opening having a major axis diameter of 270 μm, a minor axis diameter of 75 μm, and an elliptical shape at the central opening. A light-shielding plate having a hole was obtained.

[Example 1-2]
A light-shielding plate of Example 1-2 was obtained by the same method as in Example 1-1, except that the central opening was changed to a circular shape having a diameter of 850 μm in Example 1-1.

[Example 1-3]
A light-shielding plate of Example 1-3 was obtained by the same method as in Example 1-1, except that the central opening was changed to a circular shape having a diameter of 490 μm in Example 1-1.

[Example 1-4]
A light-shielding plate of Example 1-4 was obtained by the same method as in Example 1-1 except that the central opening was changed to a circular shape having a diameter of 6600 μm in Example 1-1.

[Example 1-5]
A light-shielding plate of Example 1-5 was obtained by the same method as in Example 1-1 except that the central opening was changed to a circular shape having a diameter of 2510 μm in Example 1-1.

[Example 1-6]
A light-shielding plate of Example 1-6 was obtained by the same method as in Example 1-3 except that the thickness of the stainless steel foil was changed to 25 μm in Example 1-3.

[Comparative Example 1-1]
In Example 1-2, the light-shielding of Comparative Example 1-1 was performed by the same method as in Example 1-1, except that the stainless steel foil was punched out with a die to form a circular hole penetrating the stainless steel foil. I got a board. In the light-shielding plate of Comparative Example 1-1, the diameter of the front surface opening and the diameter of the back surface opening were the same, and were the same as the second diameter of Example 1-2.

[Evaluation results]
A confocal laser scanning microscope (VK-X1000Series, manufactured by KEYENCE CORPORATION) was used for each of the light-shielding plates of Examples 1-1 to 1-6 and Comparative Example 1-1 from the direction facing the surface. The profile of the second hole portion was measured. In addition, the profile of the second hole portion was measured from the direction facing the back surface using a confocal laser scanning microscope (same as above). Then, the ratio of the second distance D12 to the first distance D11 (D12 / D11) was calculated based on the profile of the first hole portion and the profile of the second hole portion. The ratio of the second distance D12 to the first distance D11 is as shown in Table 1 below. As described above, the light-shielding plate of Comparative Example 1 does not have a hole having a first hole portion and a second hole portion. Therefore, Table 1 shows the second distance with respect to the first distance D11 in Comparative Example 1. The ratio of D12 is not stated.

As shown in Table 1, the ratio of the second distance D12 to the first distance D11 is 3.84 in Example 1-1, 3.35 in Example 1-2, and in Example 1-3. It was found to be 2.61. The ratio of the second distance D12 to the first distance D11 is 2.90 in Examples 1-4, 2.57 in Examples 1-5, and 84.65 in Examples 1-6. Was recognized. As described above, in each of the examples, it was confirmed that the ratio of the second distance D12 to the first distance D11 was 2.5 or more.

Further, based on the profile of the second hole portion, in the imaging result of each shading plate, the side surface of the second hole portion was divided into five equal parts along the radial direction of the surface opening, and the inclination angle in each region was calculated. The calculation results are as shown in Tables 2 and 3 below. In Tables 2 and 3, the horizontal distance is the length of each region along the radial direction of the surface opening. Further, in Tables 2 and 3, the height difference is the difference between the position of one end and the position of the other end of each region in the thickness direction of the light-shielding plate.

As shown in Tables 2 and 3, in Example 1-1, by setting the horizontal distance in each region to 6.5 μm or 6.7 μm, the side surface for partitioning the second hole portion is set in the radial direction of the surface opening. Divided into 5 equal parts. In Example 1-2, the side surface partitioning the second hole portion was divided into five equal parts in the radial direction of the surface opening by setting the horizontal distance in each region to 9.5 μm or 9.6 μm. In Example 1-3, the horizontal distance in each region is set to 8.1 μm, and in Example 1-4, the horizontal distance in each region is set to 7.2 μm to partition the second hole portion. The side surface to be used was divided into 5 equal parts in the radial direction of the surface opening. In Examples 1-5, the side surface partitioning the second hole portion was divided into five equal parts in the radial direction of the surface opening by setting the horizontal distance in each region to 6.9 μm or 7.1 μm. In Examples 1-6, the side surface partitioning the second hole portion was divided into five equal parts in the radial direction of the surface opening by setting the horizontal distance in each region to 7.7 μm or 7.6 μm.

Further, as shown in Tables 2 and 3, in all of Examples 1-1 to 1-6, among the first to fifth regions, the first inclination angle θ11 in the first region is It was found that it was the largest and the first inclination angle θ11 was 50 ° or more and 60 ° or less. Further, in any of Examples 1-1 to 1-6, the inclination angle becomes smaller in order from the first inclination angle θ11 to the fourth inclination angle θ14, and the fifth inclination angle θ15 becomes the fifth. 4 It was found that the inclination angle was larger than θ14.

The same object was photographed in the same environment by the camera unit equipped with each shading plate. Almost no ghosts and flares were observed in the images taken by using the camera units having the respective shading plates of Examples 1-1 to 1-6. As described above, it was confirmed that the ghost and flare were suppressed when the ratio (D12 / D11) of the second distance D12 to the first distance D11 was 2.5 or more. In particular, in Examples 1-6, it was found that ghosts and flares were more suppressed as compared with Examples 1-1 to 1-5. In Examples 1-6, the area on the side surface of the first hole portion is very small as compared with Examples 1-1 to 1-5, so that a part of the light incident on the lens is a part of the lens. It is considered that ghosts and flares are further suppressed because the reflection from the surface and incident on the first hole portion and further reflected from the first hole portion toward the lens can be remarkably suppressed. On the other hand, it was found that ghosts and flares occurred in the images taken by the camera unit having the light-shielding plate of Comparative Example 1-1.

As described above, according to the first embodiment of the shading plate, the camera unit, and the electronic device, the effects described below can be obtained.
(1-1) In the light-shielding plate 10, since the second hole portion 10H2 has a shape that tapers from the front surface 10F toward the back surface 10R, the light incident on the hole 10H from diagonally above the front surface 10F is the first hole portion 10H1. Is easily reflected toward the surface 10F of the light-shielding plate 10 on the side surface for partitioning.

(1-2) Since the ratio (D12 / D11) of the second distance D12 between the front surface 10F and the central opening HC to the first distance D11 between the back surface 10R and the central opening HC is 2.5 or more. It is possible to maintain the size of the second hole portion 10H2 to a size that can be tapered from the front surface 10F to the back surface 10R. This makes it possible to reduce the amount of light reflected on the side surface that partitions the hole 10H so as to pass through the hole 10H.

(1-3) When the first inclination angle θ11 in the first region R1 is larger than the inclination angle in each of the second region R2 to the fifth region R5, the diameter of the second hole portion 10H2 becomes excessively large. While suppressing this, it is possible to make it easier for light to be reflected toward the surface 10F of the light-shielding plate 10 in a region other than the first region R1.

(1-4) When the first inclination angle θ11 is 50 ° or more and 60 ° or less, the light-shielding plate 10 is formed in the first region R1 including the surface opening H2F among the side surfaces for partitioning the second hole portion 10H2. It is possible to increase the certainty of reflecting light toward the surface 10F.

(1-5) When the fifth inclination angle θ15 of the fifth region R5 is larger than the fourth inclination angle θ14 of the fourth region R4, the fifth inclination angle θ15 of the fifth region R5 becomes the fourth region R4. The diameter of the second hole portion 10H2 is suppressed from being expanded as compared with the case where the angle is smaller than the fourth inclination angle θ14.

(1-6) When the inclination angle in each region becomes smaller from the first region R1 to the fourth region R4, the closer to the central opening HC, the light incident on the second hole portion 10H2 is blocked by the light shielding plate. It becomes easy to reflect toward the surface 10F of 10.

(1-7) When the side surface partitioning the second hole portion 10H2 has an arc shape such that the center of curvature is located outside the shading plate 10, the specular reflected light having the highest brightness among the reflected light. Is reflected along the direction from the arc-shaped side surface toward the surface 10F of the light-shielding plate 10.

(1-8) When the side surface partitioning the first hole portion 10H1 has an arc shape such that the center of curvature is located outside the light-shielding plate 10, the light incident on the hole from diagonally above the surface 10F The amount of light reflected by the side surface that partitions the hole 10H in the vicinity of the back surface opening H1R can be reduced.

The above-mentioned first embodiment can be modified and implemented as follows.
[1st hole part]
The side surface that partitions the first hole portion 10H1 may have a linear shape in a cross section along a plane orthogonal to the surface 10F. Even in this case, the first hole portion 10H1 has a shape that tapers from the back surface 10R to the front surface 10F, and the second hole portion 10H2 has a shape that tapers from the front surface 10F to the back surface 10R. If the ratio of the second distance D12 to the one distance D11 is 2.5 or more, the effect according to (1-1) described above can be obtained.

[Second hole part]
The side surface that partitions the second hole portion 10H2 may have a linear shape in a cross section along a plane orthogonal to the surface 10F. Even in this case, the first hole portion 10H1 has a shape that tapers from the back surface 10R to the front surface 10F, and the second hole portion 10H2 has a shape that tapers from the front surface 10F to the back surface 10R. If the ratio of the second distance D12 to the one distance D11 is 2.5 or more, the effect according to (1-1) described above can be obtained.

[Side surface for partitioning the second hole]
-The inclination angle in each region may gradually decrease from the first region R1 to the fifth region R5. Even in this case, if the ratio of the second distance D12 to the first distance D11 is 2.5 or more, the effect according to (1-1) described above can be obtained.

-The inclination angle in each region does not have to decrease in order from the first region R1 to the fourth region R4. For example, in the first region R1 to the fourth region R4, the inclination angle in each region may be equal to the inclination angle in the other regions. Even in this case, if the ratio of the second distance D12 to the first distance D11 is 2.5 or more, the effect according to (1-1) described above can be obtained.

The fifth inclination angle θ15 of the fifth region R5 may be smaller than the fourth inclination angle θ14 of the fourth region R4. Even in this case, if the ratio of the second distance D12 to the first distance D11 is 2.5 or more, the effect according to (1-1) described above can be obtained.

The first inclination angle θ11 of the first region R1 may be smaller than 50 ° or larger than 60 °. Even in this case, if the ratio of the second distance D12 to the first distance D11 is 2.5 or more, the effect according to (1-1) described above can be obtained.

The first inclination angle θ11 of the first region R1 may be smaller than the inclination angle in at least one region from the second region R2 to the fifth region R5. Even in this case, if the ratio of the second distance D12 to the first distance D11 is 2.5 or more, the effect according to (1-1) described above can be obtained.

[Shading plate]
-As described above, the light-shielding plate 10 may be formed of a metal other than stainless steel. The light-shielding plate 10 may be made of, for example, an iron-nickel alloy or an iron-nickel-cobalt alloy.

The coefficient of thermal expansion of iron-nickel alloys is smaller than the coefficient of thermal expansion of stainless steel. Therefore, the light-shielding plate made of an iron-nickel alloy has a small deformation due to a change in the outside air temperature, and as a result, the change in the outside air temperature due to the deformation of the inner diameter due to the warp of the light-shielding plate itself and the thermal expansion and contraction. It is possible to suppress the change in the incident amount of external light due to the above. The incident amount of external light is the incident amount of external light incident on the lens through the light-shielding plate 10. Therefore, the fact that the light-shielding plate 10 is formed of an iron-nickel alloy is effective in suppressing ghosts and flares caused by changes in the amount of incident light.

The iron-nickel alloy is an alloy containing iron and nickel as main components, and for example, 30% by mass or more of nickel and iron as a residual. Among the iron-nickel alloys, an alloy containing 36% by mass of nickel, that is, Invar, is preferable as a material for forming the light-shielding plate 10. In Invar, the residue for 36% by weight nickel may contain additives other than iron, which is the main component. Additives include, for example, chromium, manganese, carbon, and cobalt. The maximum amount of additives contained in the iron-nickel alloy is 1% by mass or less.

The coefficient of thermal expansion of the iron-nickel-cobalt alloy is smaller than the coefficient of thermal expansion of the iron-nickel alloy. Therefore, the light-shielding plate made of iron-nickel-cobalt alloy has less deformation due to changes in the outside air temperature, which causes the outer diameter to be deformed due to the warp of the light-shielding plate itself and the deformation of the inner diameter due to thermal expansion and contraction. It is possible to further suppress the change in the incident amount of external light due to the change in air temperature. Therefore, the formation of the light-shielding plate 10 by the iron-nickel-cobalt alloy is more effective in suppressing ghosts and flares caused by changes in the amount of incident light.

The iron-nickel-cobalt alloy contains iron, nickel, and cobalt as main components, and contains, for example, 30% by mass or more of nickel, 3% by mass or more of cobalt, and iron as a residue. It is an alloy. Among the iron-nickel-cobalt alloys, an alloy containing 32% by mass of nickel and 4% by mass or more and 5% by mass or less of cobalt, that is, Super Invar is preferable as a material for forming the light-shielding plate 10. In Super Invar, the residue for 32% by mass nickel and 4% by mass or more and 5% by mass or less of cobalt may contain additives other than iron as a main component. Additives are, for example, chromium, manganese, and carbon. The maximum amount of additives contained in the iron-nickel-cobalt alloy is 0.5% by mass or less.

As described above, when the light-shielding plate 10 is made of an iron-nickel alloy or an iron-nickel-cobalt alloy, the following effects can be obtained.

(1-9) Deformation of the light-shielding plate 10 due to a change in the outside air temperature can be suppressed, and thus a change in the incident amount of outside light due to a change in the outside air temperature can be suppressed. Therefore, it is possible to suppress the occurrence of ghosts and flares due to changes in the incident amount of external light.

[Second Embodiment]
A second embodiment of the shading plate, the camera unit, and the electronic device will be described with reference to FIGS. 10 and 11. In the second embodiment, the shape of the light-shielding plate is different from that in the first embodiment described above. Therefore, while these differences will be described in detail below, other explanations will be omitted. Hereinafter, the light-shielding plate and the examples will be described in order.

[Shading plate]
The shading plate will be described with reference to FIG.

FIG. 10 shows an enlarged part of the cross-sectional structure of the light-shielding plate 10 shown in FIG.
As shown in FIG. 10, under the imaging condition where the depth of field is 0.4 μm, the edge of the central aperture HC is imaged along the radial direction of the central aperture HC while focusing on the edge of the central aperture HC. The maximum width of the light-shielding plate 10 in the thickness direction of the light-shielding plate 10 in focus is the maximum width WM. That is, the maximum width WM is the thickness of the light-shielding plate 10 at a position separated from the edge of the central opening HC by the same distance as the depth of field DF along the direction orthogonal to the thickness direction of the light-shielding plate 10. ..

The maximum width WM is 7.0 μm or less. Further, the maximum width WM is 30% or less of the thickness T of the light-shielding plate 10. The maximum width WM may be 3.0 μm or less. Further, the maximum width WM may be 1.0 μm or more. The maximum width WM may satisfy only either 7.0 μm or less and 30% or less of the thickness T of the light-shielding plate 10, but may not satisfy the other.

The distance between the back surface 10R and the edge of the central opening HC in the thickness direction of the shading plate 10 is the opening distance D21. The opening distance D21 may be larger than 0 μm and 3 μm or less. Alternatively, the opening distance D21 may be 30% or less of the thickness of the shading plate 10. The opening distance D21 does not have to satisfy that it is 30% or less of the thickness of the light-shielding plate 10 but that it is 3 μm or less. The opening distance D21 may be smaller than the maximum width WM or may be substantially equal to the maximum width WM.

Light incident on the light-shielding plate 10 from a direction orthogonal to the surface 10F enters the hole 10H through the surface opening H2F formed on the surface 10F. Then, the light that has passed through the hole 10H reaches the lens LN by exiting from the back surface opening H1R formed on the back surface 10R. On the other hand, in the light-shielding plate 10, since the second hole portion 10H2 has a shape that tapers from the front surface 10F toward the back surface 10R, the light incident on the hole 10H from diagonally above the front surface 10F partitions the second hole portion 10H2. It is easy to be reflected toward the surface 10F of the light-shielding plate 10 on the side surface.

Further, since the maximum width WM is 7.0 μm or less, or because the maximum width WM is 30% or less of the thickness T of the light-shielding plate 10, the area of the side surface for partitioning the hole 10H in the vicinity of the central opening HC is set. By making it smaller, it is possible to reduce the amount of light reflected on the side surface that partitions the hole 10H in the vicinity of the central opening HC. As a result, the amount of light reflected by the side surface that partitions the hole 10H so as to pass through the hole 10H can be reduced. When the maximum width WM is 3.0 μm or less, the area of the side surface that partitions the hole in the vicinity of the central opening HC is further reduced, so that the light is reflected on the side surface that partitions the hole 10H in the vicinity of the central opening HC. The amount of light emitted can be further reduced.

Further, when the maximum width WM is 1.0 μm or more, the thickness of the portion of the light-shielding plate 10 including the central opening HC is 1.0 μm or more, so that deformation in the vicinity of the central opening HC can be suppressed. Is. As a result, the amount of light transmitted through the light-shielding plate 10 through the central opening HC is suppressed from fluctuating due to the deformation of the light-shielding plate 10.

Further, when the opening distance D21 is larger than 0 μm and 3 μm or less, or 30% or less of the thickness of the light-shielding plate 10, the area of the side surface for partitioning the first hole portion 10H1 is reduced, whereby the first hole portion 10H1 is divided. The amount of light reflected on the side surface that partitions the hole portion 10H1 can be reduced. As a result, the amount of light reflected by the side surface that partitions the hole 10H so as to pass through the hole 10H can be reduced.

[Example]
Examples and comparative examples will be described with reference to FIG.
[Example 2-1]
A stainless steel foil having a thickness of 25 μm was prepared. Then, after the first hole portion was formed by etching the stainless steel foil from the back surface of the stainless steel foil, the second hole portion was formed by etching the stainless steel foil from the front surface of the stainless steel foil. As a result, a light-shielding plate having a hole formed from the first hole portion and the second hole portion was obtained.

[Example 2-2]
A light-shielding plate of Example 2-2 was obtained by the same method as in Example 2-1 except that the second diameter of the surface opening of the second hole portion was increased in Example 2-1.

[Example 2-3]
A light-shielding plate of Example 2-3 was obtained by the same method as in Example 2-2 except that the second diameter of the surface opening of the second hole portion was reduced in Example 2-2.

[Comparative Example 2-1]
In Example 2-1 the light-shielding plate of Comparative Example 1 was formed by the same method as in Example 2-1 except that the stainless steel foil was punched out with a die to form a circular hole penetrating the stainless steel foil. Obtained. In the light-shielding plate of Comparative Example 1, the diameter of the front surface opening and the diameter of the back surface opening were the same, and were the same as the second diameter of Example 2-1.

[Evaluation results]
The maximum width WM was measured using a confocal laser scanning microscope (VK-X1000Series, manufactured by KEYENCE CORPORATION) for each of the light-shielding plates of Examples 2-1 to 2-3 and Comparative Example 2-1. did. At this time, a 50x objective lens was attached to the confocal laser scanning microscope. In addition, the maximum width WM was measured by observing the side surface with a confocal laser microscope in a state where the edge of the central opening was in focus from the direction facing the side surface that partitions the hole. In a confocal laser microscope, the range of focus, that is, the depth of field differs depending on the magnification of the objective lens. Further, since the focus is set within the depth of field, the maximum width of the light-shielding plate in the thickness direction differs depending on the position from the edge of the central opening. Therefore, the thickness of the light-shielding plate at the position where it is actually in focus has a predetermined width. The depth of field of the 50x objective lens is 0.4 μm. Therefore, when the depth of field is 0.4 μm and the edge of the central opening is in focus, the maximum value of the width of the light-shielding plate in the thickness direction of the light-shielding plate is defined as the maximum width. That is, the thickness of the light-shielding plate at a position separated by the depth of field from the edge of the central opening is the maximum width WM of the light-shielding plate. The measurement results of the maximum width WM are as shown in Table 4.

Each of Example 2-1 to Example 2-3 and Comparative Example 2-1 was cut along a plane orthogonal to the surface to prepare a measurement target. Of these, the results of photographing the measurement target of Example 2-1 with a scanning electron microscope were as shown in FIG. In addition, the results of measuring the opening distance for each of Examples 2-1 to 2-3 and Comparative Example 2-1 are as shown in Table 4. Since the holes of the light-shielding plate of Comparative Example 2-1 do not have the first hole portion, the second hole portion, and the central opening, the maximum width and the opening distance are shown for Comparative Example 2-1. Not.

As shown in Table 1, the maximum width WM of Example 2-1 is 2.3 μm, the maximum width WM of Example 2-2 is 0.6 μm, and the maximum width WM of Example 2-3 is 6. It was found to be .96 μm. As described above, it was confirmed that the maximum width WM was 7.0 μm or less in each of Examples 2-1 to 2-3. As shown in Table 4, the opening distance D21 of Example 2-1 is 0.27 μm, the opening distance D21 of Example 2-2 is 0.10 μm, and the opening distance D21 of Example 2-3 is 7. It was found to be 0.05 μm.

Further, as shown in FIG. 11, in the light-shielding plate of Example 2-1 it was found that the first hole portion had a back surface opening H1R and a central opening HC. It was found that the light-shielding plate of Example 2-2 and the light-shielding plate of Example 2-3 also had holes having a shape similar to the shape of the holes of the light-shielding plate of Example 2-1.

Before forming the measurement target from each shading plate, the same object was photographed in the same environment by the camera unit equipped with each shading plate. Images taken by the camera unit were evaluated according to the following levels.

◎ No ghosts and almost no flare ○ No ghosts and flare that does not significantly reduce the contrast of the image △ Ghosts occur only in a part of the image and the contrast of the image is increased. Flare that does not reduce occurs × Ghost that spreads over a wide area of the image and flare that greatly reduces the contrast of the image occur

As shown in Table 4, the evaluation result when the light-shielding plate of Example 2-1 was used was "◎", and the evaluation result when the light-shielding plate of Example 2-2 was used was "○". , It was confirmed that the evaluation result when the light-shielding plate of Example 2-3 was used was "Δ". Further, as shown in Table 4, it was confirmed that the evaluation result when the light-shielding plate of Comparative Example 1 was used was “x”.

As described above, according to Examples 2-1 to 2-3, it was recognized that ghosts and flares were reduced as compared with Comparative Example 2-1. Therefore, according to Examples 2-1 to 2-3, it can be said that it is possible to reduce the amount of light reflected on the side surface that partitions the holes so as to pass through the holes of the light-shielding plate. According to Example 2-3, it is possible to reduce the amount of light reflected on the side surface that partitions the holes so as to pass through the holes of the light-shielding plate as compared with Comparative Example 2-1. Ghosts and flares are confirmed. Therefore, it can be said that the maximum width WM is preferably 7.0 μm or less. Further, according to Example 2-2, it is possible to reduce the amount of light reflected on the side surface that partitions the holes so as to pass through the holes of the light-shielding plate as compared with Comparative Example 2-1. Compared with Example 2-1 it is considered that the amount of light reflected on the side surface that partitions the hole so as to pass through the hole of the light-shielding plate is high. Since it is considered that such a difference in the amount of light is caused by the deformation of the light-shielding plate due to the decrease in strength, it can be said that the maximum width WM is preferably 1.0 μm or more in order to suppress the deformation of the light-shielding plate.

As described above, according to the second embodiment of the shading plate, the camera unit, and the electronic device, the effects described below can be obtained.
(2-1) When the maximum width WM is 7.0 μm or less, the area of the side surface for partitioning the hole 10H in the vicinity of the central opening HC is reduced, thereby partitioning the hole 10H in the vicinity of the central opening HC. The amount of light reflected on the side surface can be reduced. As a result, the amount of light reflected by the side surface that partitions the hole 10H so as to pass through the hole 10H can be reduced.

(2-2) When the maximum width WM is 3.0 μm or less, the amount of light reflected on the side surface that partitions the hole 10H in the vicinity of the central opening HC can be further reduced. As a result, the amount of light reflected by the side surface that partitions the hole so as to pass through the hole 10H can be further reduced.

(2-3) When the maximum width WM is 1.0 μm or more, it is possible to suppress deformation in the vicinity of the central opening HC. As a result, the amount of light transmitted through the light-shielding plate 10 through the central opening HC is suppressed from fluctuating due to the deformation of the light-shielding plate 10.

(2-4) When the opening distance D21 is 3.0 μm or less, the area of the side surface that partitions the first hole portion 10H1 is reduced, and thereby the light reflected on the side surface that partitions the first hole portion 10H1. The amount of light can be reduced. As a result, the amount of light reflected by the side surface that partitions the hole 10H so as to pass through the hole 10H can be reduced.

(2-5) When the opening distance D21 is 30% or less of the thickness of the light-shielding plate 10, the area of the side surface for partitioning the first hole portion 10H1 is reduced, thereby partitioning the first hole portion 10H1. The amount of light reflected on the side surface can be reduced. As a result, the amount of light reflected by the side surface that partitions the hole 10H so as to pass through the hole 10H can be reduced.

(2-6) Since the maximum width WM is 30% or less of the thickness of the light-shielding plate 10, the area of the side surface that partitions the hole 10H in the vicinity of the central opening HC is reduced, thereby reducing the area of the side surface in the vicinity of the central opening HC. The amount of light reflected on the side surface of the hole 10H can be reduced. As a result, the amount of light reflected by the side surface that partitions the hole 10H so as to pass through the hole 10H can be reduced.

The second embodiment described above can be modified and implemented as follows.
[Aperture distance]
The opening distance D21 may be larger than 3 μm. Even in this case, when the maximum width WM is 7.0 μm or less, the effect according to (2-1) described above can be obtained. Even in this case, if the maximum width WM is 30% or less of the thickness of the light-shielding plate 10, the effect according to (2-6) described above can be obtained.

The opening distance D21 may be larger than 30% of the thickness of the shading plate 10. Even in this case, when the maximum width WM is 7.0 μm or less, the effect according to (2-1) described above can be obtained. Even in this case, if the maximum width WM is 30% or less of the thickness of the light-shielding plate 10, the effect according to (2-6) described above can be obtained.

[Maximum width]
The maximum width WM may be greater than 0 μm and less than 1 μm. Even in this case, when the maximum width WM is 7.0 μm or less, the effect according to (2-1) described above can be obtained. Even in this case, if the maximum width WM is 30% or less of the thickness of the light-shielding plate 10, the effect according to (2-6) described above can be obtained.

-The maximum width WM may be larger than 3.0 μm and 7.0 μm or less. Even in this case, the effect according to (2-1) described above can be obtained.

[1st hole part]
If the first hole portion 10H1 has a shape that tapers from the back surface 10R toward the front surface 10F, the side surface that partitions the first hole portion 10H1 has a linear shape in a cross section along a plane orthogonal to the front surface 10F. You may have.

[Second hole part]
If the second hole portion 10H2 has a shape that tapers from the front surface 10F to the back surface 10R, the side surface that partitions the second hole portion 10H2 has a linear shape in a cross section along a plane orthogonal to the front surface 10F. You may have.

[Shading plate]
-As described above, the light-shielding plate 10 may be formed of a metal other than stainless steel. The shading plate 10 may be formed of any of the metals listed in the modified examples of the first embodiment.

The light-shielding plate 10 of the second embodiment can be implemented in combination with the structure of the light-shielding plate 10 of the first embodiment.

[Third Embodiment]
A third embodiment of the shading plate, the camera unit, and the electronic device will be described with reference to FIGS. 12 and 13. In the third embodiment, the shape of the light-shielding plate is different from that in the first embodiment described above. Therefore, while these differences will be described in detail below, other explanations will be omitted. Hereinafter, the light-shielding plate and the examples will be described in order.

[Shading plate]
The shading plate will be described with reference to FIG.

FIG. 12 shows an enlarged part of the cross-sectional structure of the light-shielding plate 10 shown in FIG.
As shown in FIG. 12, in a cross section along a plane orthogonal to the front surface 10F, a straight line passing through the edge of the central opening HC and the edge of the back surface opening H1R, that is, a line segment is the first straight line L31. The angle formed by the first straight line L31 and the back surface 10R is the first angle θ31. The first angle θ31 is larger than 90 °. The cross section along the plane orthogonal to the surface 10F passes through the center of the surface opening H2F. Further, in a cross section along a plane orthogonal to the front surface 10F, the first straight line L31 is an arc string connecting the central opening HC and the back opening H1R.

In the cross section along the plane orthogonal to the front surface 10F, the straight line passing through the edge of the central opening HC and parallel to the back surface 10R is the reference straight line LR. The straight line connecting the edge of the central opening HC and the edge of the surface opening H2F at the shortest distance is the second straight line L32. The angle formed by the reference straight line LR and the second straight line L32 may be 20 ° or more and 40 ° or less.

When the shading plate 10 is mounted on a smartphone, a tablet personal computer, or a camera unit installed in front of a notebook personal computer, the camera unit often shoots a subject at a short distance. Therefore, the angle formed by the reference straight line LR and the second straight line L32 may be any angle included in the range of 20 ° or more and 30 ° or less in response to the increase in the angle of view. Further, when the shading plate 10 is mounted on an in-vehicle camera, the camera unit often shoots a subject from a medium distance to a long distance. Therefore, it is preferable that the angle formed by the reference straight line LR and the second straight line L32 is included in the range of 30 ° or more and 40 ° or less in response to the decrease in the angle of view.

Further, when the shading plate 10 is mounted on a camera unit installed on the back of a smartphone, the camera unit often shoots a subject from a short distance to a long distance. Therefore, the angle formed by the reference straight line LR and the second straight line L32 may be 20 ° or more and 30 ° or less in order to cope with the case where the angle of view becomes large, and it corresponds to the case where the angle of view becomes small. Then, it may be 30 ° or more and 40 ° or less.

Light incident on the light-shielding plate 10 from a direction orthogonal to the surface 10F enters the hole 10H through the surface opening H2F formed on the surface 10F. Then, the light that has passed through the hole 10H reaches the lens LN by exiting from the back surface opening H1R formed on the back surface 10R. On the other hand, in the light-shielding plate 10, since the second hole portion 10H2 has a shape that tapers from the front surface 10F toward the back surface 10R, the light incident on the hole 10H from diagonally above the front surface 10F partitions the first hole portion 10H1. It is easy to be reflected toward the surface 10F of the light-shielding plate 10 on the side surface.

Further, as compared with the case where the angle formed by the first straight line L31 and the back surface 10R is 90 °, in the light incident on the light shielding plate 10 from diagonally above the front surface 10F, in the vicinity of the back surface opening H1R. The amount of light reflected by the side surface that partitions the hole 10H can be reduced. As a result, the amount of light reflected on the side surface that partitions the hole 10H so as to pass through the hole 10H can be reduced. As a result, it is possible to prevent unintended light from entering the lens LN facing the light-shielding plate 10.

Further, the light incident on the second hole portion 10H2 from diagonally above the surface 10F is reflected on the side surface having an arc shape. Therefore, the specularly reflected light having the highest brightness among the reflected light is reflected along the direction from the arc-shaped side surface toward the surface 10F of the light-shielding plate 10. Therefore, the amount of light reflected by the side surface that partitions the hole 10H so as to pass through the hole 10H is further suppressed.

Further, as compared with the case where the angle formed by the second straight line L32 and the reference straight line LR is larger than 40 °, the direction is diagonally above the surface 10F and the amount of deviation from the direction orthogonal to the surface 10F is small. When light is incident on the side surface that partitions the hole 10H, the light incident on the side surface is likely to be reflected toward the surface 10F of the light-shielding plate 10. Therefore, the amount of light reflected on the side surface that partitions the hole 10H so as to pass through the hole is further suppressed.

[Example]
Examples and comparative examples will be described with reference to FIG.
[Example 3-1]
A stainless steel foil having a thickness of 25 μm was prepared. Then, after the first hole portion was formed by etching the stainless steel foil from the back surface of the stainless steel foil, the second hole portion was formed by etching the stainless steel foil from the front surface of the stainless steel foil. As a result, a light-shielding plate having a hole formed from the first hole portion and the second hole portion was obtained. The first diameter of the first hole portion was 490 μm, and the second diameter of the second hole portion was 571 μm.

[Comparative Example 3-1]
In Example 3-1 the light shielding of Comparative Example 3-1 by the same method as in Example 3-1 except that the stainless steel foil was punched out with a die to form a circular hole penetrating the stainless steel foil. I got a board. In the light-shielding plate of Comparative Example 3-1 the diameter of the front surface opening and the diameter of the back surface opening were the same, and were the same as the second diameter of Example 3-1.

[Comparative Example 3-2]
In Example 3-1 except that after the second hole portion was formed without forming the first hole portion, the space between the bottom portion and the back surface of the second hole portion was punched by irradiation with a laser beam. A light-shielding plate of Comparative Example 3-2 was obtained by the same method as in 1. In the light-shielding plate of Comparative Example 3-2, the diameter of the front surface opening is the same as the second diameter of Example 3-1 and the diameter of the back surface opening is the same as the first diameter of Example 3-1. there were.

[Evaluation results]
Each of the light-shielding plates of Example 3-1 and Comparative Example 3-1 and Comparative Example 3-2 was cut along a plane orthogonal to the surface to prepare a measurement target. The results of photographing the measurement target of Example 3-1 with a scanning electron microscope were as shown in FIG.

As shown in FIG. 13, in the measurement target of Example 3-1 it was found that the first angle θ31 formed by the first straight line L31 and the back surface 10R was 125 °, that is, larger than 90 °. It was. On the other hand, in the measurement target of Comparative Example 3-1 it was found that the angle formed by the side surface and the back surface was 90 ° on the entire side surface for partitioning the hole. Further, in the measurement target of Comparative Example 3-2, it was confirmed that the angle formed by the side surface and the back surface formed by the irradiation of the laser beam was 90 °.

Before forming the measurement target from each shading plate, the same object was photographed in the same environment by the camera unit equipped with each shading plate. No ghost or flare was observed in the image taken by using the camera unit having the light-shielding plate of Example 3-1. On the other hand, the images taken by the camera unit having the light-shielding plate of Comparative Example 3-1 and the images taken by the camera unit having the light-shielding plate of Comparative Example 3-2 have at least ghosts and flares. It was found that one occurred.

As described above, according to the third embodiment of the shading plate, the camera unit, and the electronic device, the effects described below can be obtained.
(3-1) The amount of light reflected by the side surface that partitions the hole 10H in the vicinity of the back surface opening H1R can be reduced. As a result, the amount of light reflected on the side surface that partitions the hole 10H so as to pass through the hole 10H can be reduced.

(3-2) Light incident on the second hole portion 10H2 from diagonally above the surface 10F is reflected on the side surface having an arc shape. Therefore, the specularly reflected light having the highest brightness among the reflected light is reflected along the direction from the arc-shaped side surface toward the surface 10F of the light-shielding plate 10. Therefore, the amount of light reflected by the side surface that partitions the hole 10H so as to pass through the hole 10H is further suppressed.

(3-3) In the light-shielding plate 10, the side surface that partitions the first hole portion 10H1 has an arc shape such that the center of curvature is located outside the light-shielding plate 10. Therefore, as compared with the case where the side surface for partitioning the first hole portion 10H1 has a linear shape, the light incident on the hole from diagonally above the front surface 10F is reflected by the side surface for partitioning the hole 10H in the vicinity of the back surface opening H1R. The amount of light produced can be reduced. As a result, the amount of light reflected by the side surface that partitions the hole 10H so as to pass through the hole 10H can be further reduced.

(3-4) Amount of deviation from the direction diagonally above the surface 10F and orthogonal to the surface 10F, as compared with the case where the angle formed by the second straight line L32 and the reference straight line LR is larger than 40 °. When light is incident on the side surface that partitions the hole 10H from a small direction, the light incident on the side surface is likely to be reflected toward the surface 10F of the light-shielding plate 10. Therefore, the amount of light reflected by the side surface that partitions the hole 10H so as to pass through the hole 10H is further suppressed.

The third embodiment described above can be modified and implemented as follows.
[Second angle]
The second angle θ32 formed by the second straight line L32 and the reference straight line LR may be larger than 40 °. Even in this case, the first hole portion 10H1 has a shape that tapers from the back surface 10R to the front surface 10F, and the second hole portion 10H2 has a shape that tapers from the front surface 10F to the back surface 10R. If the first angle θ31 is larger than 90 °, the effect according to (3-1) described above can be obtained.

[1st hole part]
The side surface that partitions the first hole portion 10H1 may have a linear shape in a cross section along a plane orthogonal to the surface 10F. Even in this case, the first hole portion 10H1 has a shape that tapers from the back surface 10R to the front surface 10F, and the second hole portion 10H2 has a shape that tapers from the front surface 10F to the back surface 10R. If the first angle θ31 is larger than 90 °, the effect according to (3-1) described above can be obtained.

[Second hole part]
The side surface that partitions the second hole portion 10H2 may have a linear shape in a cross section along a plane orthogonal to the surface 10F. Even in this case, the first hole portion 10H1 has a shape that tapers from the back surface 10R to the front surface 10F, and the second hole portion 10H2 has a shape that tapers from the front surface 10F to the back surface 10R. If the first angle θ31 is larger than 90 °, the effect according to (3-1) described above can be obtained.

[Shading plate]
-As described above, the light-shielding plate 10 may be formed of a metal other than stainless steel. The shading plate 10 may be formed of any of the metals listed in the modified examples of the first embodiment.
The light-shielding plate 10 of the third embodiment can be implemented in combination with at least one of the structure of the light-shielding plate 10 of the first embodiment and the structure of the light-shielding plate 10 of the second embodiment.

Claims

It ’s a metal shading plate,
The surface located on the incident side of light and
The back surface, which is the surface opposite to the front surface,
With a hole penetrating between the front surface and the back surface,
The hole includes a first hole portion and a second hole portion connected to the first hole portion at the central opening, and the first hole portion extends from the back surface opening on the back surface to the central opening. The second hole portion has a shape that tapers from the back surface toward the front surface, extends from the surface opening on the front surface to the central opening, and has a shape that tapers from the front surface toward the back surface. , The size of the front surface opening is larger than the size of the back surface opening,
Under imaging conditions where the depth of field is 0.4 μm, when the edge of the central aperture is imaged along the radial direction of the central aperture with the edge of the central aperture in focus, the focus is achieved. A light-shielding plate having a maximum width of 7.0 μm or less in the thickness direction of the light-shielding plate.
The light-shielding plate according to claim 1, wherein the maximum width of the light-shielding plate is 3.0 μm or less.
The light-shielding plate according to claim 1 or 2, wherein the maximum width of the light-shielding plate is 1.0 μm or more.
The light-shielding plate according to any one of claims 1 to 3, wherein the distance between the back surface and the edge of the central opening is greater than 0 μm and 3 μm or less in the thickness direction of the light-shielding plate.
The shading according to any one of claims 1 to 3, wherein the distance between the back surface and the edge of the central opening is 30% or less of the thickness of the shading plate in the thickness direction of the shading plate. Board.
It ’s a metal shading plate,
The surface located on the incident side of light and
The back surface, which is the surface opposite to the front surface,
With a hole penetrating between the front surface and the back surface,
The hole includes a first hole portion and a second hole portion connected to the first hole portion at the central opening, and the first hole portion extends from the back surface opening on the back surface to the central opening. The second hole portion has a shape that tapers from the back surface toward the front surface, extends from the surface opening on the front surface to the central opening, and has a shape that tapers from the front surface toward the back surface. , The size of the front surface opening is larger than the size of the back surface opening,
Under imaging conditions where the depth of field is 0.4 μm, when the edge of the central aperture is imaged along the radial direction of the central aperture with the edge of the central aperture in focus, the focus is achieved. A light-shielding plate in which the maximum width of the light-shielding plate in the thickness direction of the light-shielding plate is 30% or less of the thickness of the light-shielding plate.
The light-shielding plate according to any one of claims 1 to 6, wherein the light-shielding plate has a thickness of 10 μm or more and 100 μm or less.
The light-shielding plate according to any one of claims 1 to 7, wherein the light-shielding plate is made of an iron-nickel alloy or an iron-nickel-cobalt alloy.
The light-shielding plate according to claim 8, wherein the light-shielding plate is made of Invar or Super Invar.
A camera unit including the light-shielding plate according to any one of claims 1 to 9.
An electronic device including the camera unit according to claim 10.