JP7172926B2 - Shades, camera units, and electronic equipment - Google Patents

Description

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

A camera unit included in an electronic device such as a smartphone includes a light shielding plate that functions as a diaphragm for external light. A light shielding plate made of resin is often used because it is easy to mold a light shielding plate having a predetermined shape (see, for example, Patent Document 1). However, the light shielding plate made of resin allows the outside light to pass through not only the holes for passing the outside light but also the portions defining the holes due to the light transmittance of the light shielding plate. In this way, since the light shielding plate made of resin does not provide sufficient light shielding, a metal light shielding plate having a higher light shielding property is beginning to be used (see, for example, Patent Document 2).

JP-A-2010-8786 WO2016/060198

By the way, since the difficulty of processing is low and it is possible to manufacture a large number of products per unit time, when manufacturing a metal light shielding plate, a punching process of punching out a metal plate with a die is used. used. In the processing of metal plates using punching, the surface of the metal plate is treated with a It is required to punch the metal plate along the direction perpendicular to the As a result, holes having side surfaces extending perpendicularly to the surface of the metal plate are formed in 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 in a camera unit, external light entering the light-shielding plate from a direction forming an acute angle with the surface of the light-shielding plate is reflected on the side surfaces defining the holes, resulting in It can pass through holes. The light that has passed through the hole is received by the imaging section provided in the camera unit, and ghosts and flares may occur in the image captured by the imaging section. As described above, the metal light shielding plate has a new problem because the light shielding plate is made of metal.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a light shielding plate, a camera unit, and an electronic device capable of reducing the amount of light reflected by the side surfaces defining the holes so as to pass through the holes.

A light shielding plate for solving the above problem is a metal light shielding plate. It has a front surface positioned on the light incident side, a rear surface opposite to the front surface, and a hole penetrating between the front surface and the rear surface. The holes have a rear surface opening on the rear surface, a first hole having a shape tapered from the rear surface to the front surface, and a front surface opening larger than the rear surface opening on the front surface. a second hole tapered toward the back surface and connected to the first hole; Of the openings of the first hole, the opening on the side opposite to the back opening is the central opening. A ratio of the distance between the front surface and the edge of the central opening to the distance between the back surface and the edge of the central opening in the thickness direction of the light shielding plate is 2.5 or more.

A camera unit for solving the above problem includes the above light shielding plate.
An electronic device for solving the above problems includes the above camera unit.

According to each of the above configurations, since the second hole has a shape that tapers from the front surface to the back surface, compared to the case where the second hole has substantially the same width from the front surface to the back surface, the The light incident on the hole is likely to be reflected toward the surface of the light shielding plate on the side surface defining the second hole. Moreover, since the ratio of the distance between the front surface and the central opening to the distance between the back surface and the central opening is 2.5 or more, the size of the second hole is tapered from the front surface toward the back surface. It is possible to maintain a size that can be This makes it possible to reduce the amount of light reflected by the side surfaces defining the holes so as to pass through the holes.

In the light shielding plate, the surface opening has a circular shape when viewed from the direction facing the surface, and the side surface defining the second hole is positioned at the center of the surface opening when viewed from the direction facing the surface. When the surface opening is divided into 5 equal parts in the radial direction by circles concentric to the edge of the surface opening among the side surfaces that partition the second hole in a cross section along a plane perpendicular to the surface may be greater than the inclination with respect to the surface in other areas of the side surface defining the second hole.

According to the above configuration, the diameter of the second hole becomes excessively large by making the inclination of the area including the edge of the surface opening larger than the inclination of the other area of the side surfaces defining the second hole. In addition, it is possible to make it easier to reflect light toward the surface of the light shielding plate in a region other than the region including the edge of the surface opening.

In the light shielding plate, in a cross section along a plane perpendicular to the surface, the inclination of the side surface defining the second hole with respect to the surface in the region including the edge of the surface opening is 50° or more and 60° or less. may be According to this configuration, it is possible to increase the reliability of reflecting light toward the surface of the light shielding plate in the area including the edge of the surface opening among the side surfaces defining the second hole.

In the light shielding plate, in a cross section along a plane orthogonal to the surface, the inclination of a region including an edge of the central opening of the side surfaces defining the second hole with respect to the surface is a region adjacent to the region. may be greater than the inclination with respect to said surface at .

According to the above configuration, the diameter of the second hole can be expanded compared to the case where the inclination with respect to the surface in the area including the edge of the central opening is smaller than the inclination with respect to the surface in the area adjacent to the area. suppressed.

In the light shielding plate, when viewed from the direction facing the surface, the side surface defining the second hole is divided into a first area and a second area along the direction from the edge of the surface opening to the edge of the central opening. A portion of the side surface defining the second hole from the first region toward the fourth region, the portion being included in each region. may be less inclined with respect to the surface at .

According to the above configuration, compared to the case where the inclination of the side surfaces defining the second hole is the same from the first region to the fourth region, the closer to the central opening, the more the light incident on the second hole is blocked by the light shielding plate. Makes it easier to reflect towards the surface.

In the light shielding plate, in a cross section along a plane orthogonal to the surface, the side surface defining the second hole is arcuate, and the center of curvature of the side surface defining the second hole is located outside the light shielding plate. may be located in

According to the above configuration, the light incident on the second hole from obliquely above the surface is reflected by the arcuate side surface. Therefore, the specularly reflected light, which has the highest brightness among the reflected lights, is reflected along the direction toward the surface of the light shielding plate from the arc-shaped side surface. Therefore, the amount of light reflected by the side surfaces defining the hole to pass through the hole is lower.

In the light shielding plate, in a cross section along a plane orthogonal to the surface, the side surface defining the first hole is arcuate, and the center of curvature of the side surface defining the first hole is located outside the light shielding plate. may be located in

According to the above configuration, the side surface defining the first hole has an arc shape with the center of curvature positioned outside the light shielding plate. It is possible to reduce the amount of light reflected by the side surfaces defining the hole in the vicinity of the back opening, among the light incident on the hole from obliquely above. As a result, the amount of light reflected by the side surfaces defining the holes so as to pass through the holes can be further reduced.

In the light shielding plate, the light shielding plate may have a thickness of 10 μm or more and 100 μm or less. According to this configuration, since the thickness of the light shielding plate is 10 μm or more, the warping of the metal foil for forming the light shielding plate can be suppressed from affecting the shape of the light shielding plate. When the thickness is 100 μm or less, deterioration in accuracy of etching for forming holes can be suppressed.

In the light shielding plate, the light shielding plate may be made of an iron-nickel alloy or an iron-nickel-cobalt alloy.
In the light shielding plate, the light shielding plate may be made of Invar or Super Invar.

According to each of the above configurations, it is possible to suppress deformation of the light shielding plate due to changes in the outside air temperature, thereby suppressing changes in the incident amount of outside light due to changes in the outside air temperature. Therefore, it is possible to suppress the occurrence of ghosts and flares due to changes in the incident amount of external light.

According to the present invention, it is possible to reduce the amount of light reflected by the side surfaces defining the holes so as to pass through the holes.

FIG. 2 is a plan view showing the structure of a light shielding plate in one embodiment; FIG. 2 is a cross-sectional view showing the structure of the light shielding plate shown in FIG. 1; FIG. 3 is a partially enlarged cross-sectional view showing an enlarged part of the cross-sectional view shown in FIG. 2; FIG. 4 is an operation diagram for explaining the operation of the light shielding plate; FIG. 4 is an operation diagram for explaining the operation of the light shielding plate; Process drawing for demonstrating the manufacturing method of a light-shielding plate. Process drawing for demonstrating the manufacturing method of a light-shielding plate. Process drawing for demonstrating the manufacturing method of a light-shielding plate. Process drawing for demonstrating the manufacturing method of a light-shielding plate.

An embodiment of a light blocking plate, a camera unit, and an electronic device will be described with reference to FIGS. 1 to 9. FIG. Hereinafter, the configuration of the light shielding plate, the method for manufacturing the light shielding plate, and the examples will be described in order.

[Construction of light shielding plate]
The configuration of the light shielding plate will be described with reference to FIGS. 1 to 5. FIG.
As shown in FIG. 1, the metal light shielding plate 10 has a front surface 10F, a rear surface 10R, and holes 10H. The surface 10F is a surface located on the light incident side. The back surface 10R is the surface opposite to the front surface 10F. The hole 10H penetrates between the front surface 10F and the rear surface 10R. The light shielding plate 10 is made of stainless steel, for example, but may be made of metal other than stainless steel. The light shielding plate 10 is covered with an antireflection film (not shown) on the front surface 10F, the rear surface 10R, and the side surfaces defining the holes 10H. The antireflection film has a reflectance lower than that of the metal forming the light shielding plate 10, and has a function of absorbing part of the light irradiated onto 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 that the hole 10H faces.

FIG. 2 shows the structure of the light shielding plate 10 in a cross section perpendicular to the surface 10F of the light shielding plate 10. As shown in FIG.
As shown in FIG. 2, the hole 10H has a first hole 10H1 and a second hole 10H2. The first hole 10H1 has a rear surface opening H1R on the rear surface 10R and has a tapered shape from the rear surface 10R toward the front surface 10F. The second hole 10H2 has a front opening H2F larger than the rear opening H1R on the front surface 10F. The second hole 10H2 has a tapered shape from the front surface 10F toward the rear surface 10R and is connected to the first hole 10H1.

In the present embodiment, in a cross section along a plane perpendicular to the surface 10F, the side surfaces defining the second holes 10H2 are arcuate, and the center of curvature of the side surfaces defining the second holes 10H2 is outside the light shielding plate 10. positioned. Further, in a cross section along a plane perpendicular to the surface 10F, the side surfaces defining the first holes 10H1 are arcuate, and the center of curvature of the side surfaces defining the first holes 10H1 is located outside the light shielding plate 10.

In the light shielding plate 10, the diameter of the first hole 10H1 is the first diameter DH1, and the diameter of the second hole 10H2 is the second diameter DH2. The first diameter DH1 is set according to the camera unit in which the light blocking 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 in, for example, a camera unit of a smartphone. 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, a vehicle-mounted camera.

A percentage (DH1/DH2×100) of the first diameter DH1 to the second diameter DH2 may be, for example, 80% or more and 99% or less. When the light shielding plate 10 is installed in a camera unit installed in front of a smartphone, a tablet personal computer, or a notebook personal computer, the camera unit often photographs a subject at a short distance. Therefore, the angle of view is increased, but the light shielding plate 10 does not need to have a large inner diameter in order for the lens to focus on the subject. In addition, it is difficult to increase the outer diameter of the light shielding plate 10 due to restrictions on the space in which the camera unit is arranged. Therefore, the percentage of the first diameter DH1 to the second diameter DH2 may be 80% or more and 90% or less.

On the other hand, when the light shielding plate 10 is mounted on an in-vehicle camera, the in-vehicle camera often photographs the subject at a medium to long distance. As a result, the angle of view becomes smaller, but the diameter of the lens included in the camera unit becomes larger because the space in which the camera unit is arranged is less restricted. Accordingly, the ratio of the first diameter DH1 to the second diameter DH2 in the light blocking plate 10 may be 90% or more and 99% or less, in order to collect a wide range of light onto the lens.

Moreover, when the light shielding plate 10 is mounted on a camera unit installed on the back of a smartphone, the camera unit often photographs a subject from a short distance to a long distance. Therefore, when the angle of view becomes large, the ratio of the first diameter DH1 to the second diameter DH2 may be 80% or more and 90% or less. A 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 of the light shielding plate 10 is 10 μm or more, it is possible to suppress the warp of the metal foil from affecting the shape of the light shielding plate 10 . Further, when the thickness of the light shielding plate 10 is 100 μm or less, it is possible to suppress the deterioration of etching precision 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, among the openings of the first hole 10H1, the opening on the side opposite to the back surface opening H1R is 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 D1. 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 D2. In the light shielding plate 10, the ratio (D2/D1) of the second distance D2 to the first distance D1 is 2.5 or more.

As the ratio (D2/D1) of the second distance D2 to the first distance D1 increases, the central opening HC relatively approaches the rear opening H1R. As a result, the side surface area of the first hole 10H1 can be reduced. Therefore, part of the light that enters the hole 10H from obliquely above the light shielding plate 10 is reflected on the surface of the lens, enters the first hole 10H1, and is reflected from the first hole 10H1 toward the lens LN. is suppressed.

In addition, it is preferable that the ratio (D2/D1) of the second distance D2 to the first distance D1 approaches infinity. However, in actuality, during the etching for forming the holes 10H, the etchant penetrates into the gap between the metal foil for forming the light shielding plate 10 and the mask formed on the metal foil. , that is, a first hole 10H1 having a first distance D1. Therefore, for example, when the metal foil has a thickness of 100 μm, the lower limit of the first distance D1 is approximately 0.1 μm. Therefore, the upper limit of the ratio (D2/D1) of the second distance D2 to the first distance D1 is about 1,000.

The surface opening H2F has a circular shape when viewed from the direction facing the surface 10F. When viewed from the direction facing the surface 10F, the side surface defining the second hole 10H2 is divided into 5 equal parts in the radial direction of the surface opening H2F by planes concentric with the center of the surface opening. In this case, when viewed from the direction facing the surface 10F, the side surfaces defining the second hole 10H2 are divided into a first region R1 and a second region R1 along the direction from the edge of the surface opening H2F to the edge of the central opening HC. It has R2, a third region R3, a fourth region R4, and a fifth region R5. In addition, the first region R1 is a region including the edge of the surface opening H2F among the side surfaces defining the second hole 10H2. The fifth region R5 is a region including the edge of the central opening HC among the side surfaces defining the second hole 10H2.

In a cross section along a plane perpendicular to the surface 10F, in each region, the inclination of a straight line connecting one end and the other end of a portion of the side surface defining the second hole 10H2 with respect to the surface 10F is is the tilt angle at the included part. In the first region R1, the angle formed by the first straight line L1 and the surface 10F is the first tilt angle θ1, and in the second region R2, the angle formed by the second straight line L2 and the surface 10F is the second tilt angle. θ2. In the third region R3, the angle formed by the third straight line L3 and the surface 10F is the third tilt angle θ3, and in the fourth region R4, the angle formed by the fourth straight line L4 and the surface 10F is the fourth tilt angle. θ4, and in the fifth region R5, the angle formed by the fifth straight line L5 and the surface 10F is the fifth tilt angle θ5.

In a cross section along a plane orthogonal to the surface 10F, the first inclination angle θ1 of the first region R1 is larger than the inclination angles of the other regions among the side surfaces defining the second hole 10H2. The first tilt angle θ1 is greater than each of the second tilt angle θ2, the third tilt angle θ3, the fourth tilt angle θ4, and the fifth tilt angle θ5. Also, the first tilt angle θ1 is 50° or more and 60° or less.

In a cross section along a plane perpendicular to the surface 10F, the fifth region R5 has a fifth inclination angle θ5 larger than the fourth inclination angle θ4 among the side surfaces defining the second hole 10H2. In addition, the inclination angles of the portions included in each of the side surfaces defining the second hole 10H2 decrease from the first region R1 toward the fourth region R4. That is, on the side surfaces defining the second hole 10H2, the inclination angles decrease in the order of the first inclination angle θ1, the second inclination angle θ2, the third inclination angle θ3, and the fourth inclination angle θ4.

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 surfaces defining the holes extend along the direction perpendicular to the surface in the cross section perpendicular to the surface. 4 and 5, for convenience of illustration, the first diameter is reduced with respect to the thickness of the light shielding plate.

As shown in FIG. 4, light incident on the light blocking 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 passing through the hole 10H reaches the lens LN by going out from the rear surface opening H1R formed in the rear surface 10R. On the other hand, in the light shielding plate 10, the second hole 10H2 has a tapered shape from the front surface 10F toward the rear surface 10R. is likely to be reflected toward the front surface 10F of the light shielding plate 10 at .

Moreover, the ratio (D1/D2) of the first distance D1 between the front surface 10F and the central opening HC to the second distance D2 between the rear surface 10R and the central opening HC is 2.5 or more. It is possible to maintain the size of the hole 10H2 at a size that allows the shape to taper from the front surface 10F toward the back surface 10R. As a result, it is possible to reduce the amount of light reflected by the side surfaces defining the hole 10H so as to pass through the hole 10H. As a result, unintended incidence of light on the lens LN facing the light shielding plate 10 is suppressed.

In this embodiment, the first tilt angle θ1 in the first region R1 is larger than the tilt angles in each of the second region R2 to the fifth region R5. Therefore, while preventing the diameter of the second hole 10H2 from becoming excessively large, it is possible to make it easier to reflect light toward the surface 10F of the light shielding plate 10 in regions other than the first region R1. Since the first inclination angle θ1 is 50° or more and 60° or less, light is directed toward the surface 10F of the light shielding plate 10 in the first region R1 including the surface opening H2F among the side surfaces defining the second hole 10H2. can be enhanced.

In the present embodiment, the fifth tilt angle θ5 of the fifth region R5 is larger than the fourth tilt angle θ4 of the fourth region R4, so the fifth tilt angle θ5 of the fifth region R5 is the fourth tilt angle θ5 of the fourth region R4. Expansion of the diameter of the second hole 10H2 is suppressed as compared with the case where the inclination angle is smaller than 4 tilt angles θ4. In addition, since the inclination angle in each area decreases from the first area R1 to the fourth area R4, the inclination of the side surfaces defining the second hole 10H2 is the same from the first area R1 to the fourth area R4. Compared to a certain case, the closer to the central opening HC, the easier it is to reflect the light that has entered the second hole 10H2 toward the surface 10F of the light shielding plate 10 .

Also, the light incident on the second hole 10H2 from obliquely above the surface 10F is reflected by the arcuate side surface of which the center of curvature is positioned outside the light shielding plate 10. FIG. Therefore, the specularly reflected light having the highest brightness among the reflected lights is reflected along the direction toward the surface 10F of the light shielding plate 10 from the arc-shaped side surface. Therefore, the amount of light reflected by the side surfaces defining the hole 10H so as to pass through the hole 10H is further suppressed.

The light shielding plate 10 has an arcuate side surface defining the first hole 10H1 with the center of curvature located outside the light shielding plate 10 . Therefore, compared to the case where the side surfaces defining the first hole 10H1 are linear, the light incident on the hole from obliquely above the front surface 10F is reflected by the side surfaces defining the hole 10H in the vicinity of the back opening H1R. It is possible to reduce the amount of light that is emitted. As a result, the amount of light reflected by the side surfaces defining 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 perpendicular to the surface 100F is formed on the surface 100F in the same manner as the light incident on the light shielding plate 10 from the direction perpendicular to the surface 10F. It enters the hole 100H through the opening. Then, the light passing through the hole 100H reaches the lens LN by going out from the opening formed in the rear surface 100R. On the other hand, part of the light incident on the surface 100F from obliquely above the surface 100F enters the hole 100H through the opening formed in the surface 100F and is reflected by the side surfaces defining the hole 100H. Since most of the light that has entered the side surface is reflected in the direction of regular reflection, the light that has entered the side surface is reflected from the side surface toward the lens LN. As a result, unintended light enters the imaging section through the lens LN.

One or more light shielding plates 10 described above are provided in the camera unit described above. A camera unit including the light shielding plate 10 is mounted on various electronic devices. An electronic device including a camera unit may be, for example, a smart phone, a tablet personal computer, a notebook personal computer, or the like.

[Method for manufacturing light shielding plate]
A method of manufacturing the light shielding plate 10 will be described with reference to FIGS. Each of FIGS. 6 to 9 shows the cross-sectional structure of the metal foil at a specific step in the manufacturing process of the light shielding plate 10. FIG. 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 shield plate, and the ratio of the first diameter DH1 to the thickness of the metal foil is It is smaller than the actual light shielding plate. Also, 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. 6 to 9 show only the steps related to the formation of the holes 10H of the light shielding plate 10 among the steps of manufacturing the light shielding plate 10 for convenience of explanation.

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 may be a metal foil made of a metal other than stainless steel, as described above. 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, the influence of the warp of the metal foil 10M on the shape of the light shielding plate 10 is suppressed. In addition, when the thickness of the metal foil 10M is 100 μm or less, it is possible to suppress a decrease in accuracy of etching 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 rear 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 rear surface 10MR of the metal foil 10M corresponds to the rear surface 10R of the light shielding plate 10. A front resist layer RF is arranged on the front surface 10MF of the metal foil 10M, and a rear resist layer RR is arranged on the rear surface 10MR of the metal foil 10M. A dry film resist may be applied as the resist layers RF and RR to both the front surface 10MF and the rear surface 10MR. Alternatively, resist layers RF and RR may be formed on both front surface 10MF and back surface 10MR using a coating liquid for forming resist layers RF and RR. The resist layers RF and RR may be formed of a negative resist or a positive resist.

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

As shown in FIG. 8, a rear surface mask RMR formed on the rear surface 10MR is used to form a first hole MH1 having a rear surface opening on the rear surface 10MR and a tapered shape from the rear surface 10MR toward the front surface 10MF. A metal foil 10M is formed. The first hole MH1 corresponds to the first hole 10H1 that the light shielding plate 10 has. At this time, the metal foil 10M is etched using an etchant capable of etching the metal foil 10M. Before etching the metal foil 10M, the surface mask RMF is covered with a surface protective film PMF that is resistant to the etchant. 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, the front surface 10MF of the metal foil 10M is prevented from being etched simultaneously with the back surface 10MR of the metal foil 10M.

When the first hole MH1 is formed by etching the rear surface 10MR, the first hole MH1 having a depth greater than the distance between the rear surface 10R and the central opening HC of the light shielding plate 10 is formed. be done.

As shown in FIG. 9, after forming the first hole MH1, a surface mask RMF formed on the surface 10MF is used to have a surface opening on the surface 10MF and taper from the surface 10MF to the back surface 10MR. A shaped second hole MH2 is formed in the metal foil 10M so as to be connected to the first hole MH1. The second hole MH2 corresponds to the second hole 10H2 that the light shielding plate 10 has. At this time, similarly to when forming the first holes MH1, the metal foil 10M is etched using an etchant capable of etching the metal foil 10M. Before etching the metal foil 10M, the back surface mask RMR is removed from the back surface 10MR of the metal foil 10M.

In addition, before etching the metal foil 10M, the back surface protective film PMR having resistance to the etchant covers the back surface 10MR of the metal foil 10M and fills the first holes MH1. By covering the back surface 10MR of the metal foil 10M with the back surface protective film PMR, the back surface 10MR of the metal foil 10M is prevented from being etched simultaneously with the front surface 10MF of the metal foil 10M.

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

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

The antireflection coating is, for example, a black coating. The antireflection film may be formed on the metal foil 10M using a film forming method such as a sputtering method or a vapor deposition method. Alternatively, the antireflection coating may be formed on the metal foil 10M by exposing the metal foil 10M to a liquid for forming the antireflection coating.

With this method of manufacturing the light shielding plate 10, one hole 10H is provided, and the distance between the front surface 10F and the edge of the central opening HC relative to the distance between the back surface 10R and the edge of the central opening HC in the thickness direction of the light shielding plate 10 is reduced. A light shielding plate 10 having a ratio of distances between them of 2.5 or more is manufactured.

In the above-described method for manufacturing the light shielding plate 10, the back surface mask RMR does not need to be removed before forming the back surface protective film PMR. In this case, a back surface protective film PMR that covers the back surface mask RMR and fills the first holes MH1 may be formed. Also, the back surface protective film PMR may be removed from the back surface 10MR together with the back surface mask RMR after the second holes MH2 are formed by etching the front surface 10MF.

[Example]
An example will be described.
[Example 1]
A stainless steel foil having a thickness of 30 μm was prepared. Then, after forming the first holes by etching the stainless steel foil from the back side of the stainless steel foil, the second holes were formed by etching the stainless steel foil from the front side. As a result, a light shielding plate having a first hole, a second hole, and an elliptical central opening was obtained.

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

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

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

[Example 5]
A light shielding plate of Example 4 was obtained in the same manner as in Example 1, except that the central opening was changed to a circular shape with a diameter of 2510 μm.

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

[Comparative Example 1]
A light-shielding plate of Comparative Example 1 was obtained in the same manner as in Example 1, except that circular holes were formed through the stainless steel foil by punching the stainless steel foil with a die. In addition, in the light shielding plate of Comparative Example 1, the diameter of the front opening and the diameter of the rear opening were the same, and were the same as the second diameter of the second embodiment.

[Evaluation results]
For each of the light shielding plates of Examples 1 to 6 and Comparative Example 1, from the direction facing the surface, using a confocal laser microscope (VK-X1000 Series, manufactured by Keyence Corporation), the second hole profile was measured. In addition, the profile of the second hole was measured from the direction facing the back surface using a confocal laser microscope (same as above). Then, based on the profile of the first hole and the profile of the second hole, the ratio (D2/D1) of the second distance D2 to the first distance D1 was calculated. The ratio of the second distance D2 to the first distance D1 was as shown in Table 1 below. As described above, the light shielding plate of Comparative Example 1 does not have a hole having the first hole and the second hole. No ratio is given.

As shown in Table 1, the ratio of the second distance D2 to the first distance D1 is 3.84 in Example 1, 3.35 in Example 2, and 2.61 in Example 3. was accepted. Also, the ratio of the second distance D2 to the first distance D1 was found to be 2.90 in Example 4, 2.57 in Example 5, and 84.65 in Example 6. Thus, it was confirmed that the ratio of the second distance D2 to the first distance D1 was 2.5 or more in any of the examples.

Further, based on the profile of the second hole, the side surface of the second hole was equally divided into 5 along the radial direction of the surface opening in the imaging result of each light shielding plate, and the inclination angle in each area was calculated. The calculation results were as shown in Tables 2 and 3 below. In Tables 2 and 3, the horizontal distance is the length of each area along the radial direction of the surface opening in the direction facing the surface. In Tables 2 and 3, the height difference is the difference between the positions of one end and 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, by setting the horizontal distance in each region to 6.5 μm or 6.7 μm, the side surface defining the second hole is 5 or so in the radial direction of the surface opening. divided. In Example 2, by setting the horizontal distance in each region to 9.5 μm or 9.6 μm, the side surfaces defining the second holes were equally divided into five in the radial direction of the surface opening. In Example 3, the horizontal distance in each region was set to 8.1 μm, and in Example 4, the horizontal distance in each region was set to 7.2 μm. was divided into 5 equal parts in the radial direction. In Example 5, by setting the horizontal distance in each region to 6.9 μm or 7.1 μm, the side surface defining the second hole was divided into 5 equal parts in the radial direction of the surface opening. In Example 6, by setting the horizontal distance in each area to 7.7 μm or 7.6 μm, the side surfaces defining the second holes were equally divided into five in the radial direction of the surface opening.

Further, as shown in Tables 2 and 3, in any of Examples 1 to 6, among the first to fifth regions, the first tilt angle θ1 in the first region is the largest, and , the first inclination angle θ1 was found to be 50° or more and 60° or less. Furthermore, in any one of the first to sixth embodiments, the inclination angle decreases in order from the first inclination angle θ1 to the fourth inclination angle θ4, and the fifth inclination angle θ5 becomes the fourth inclination angle θ4. was found to be greater than

The same object was photographed under the same environment using a camera unit equipped with each light shielding plate. Almost no ghost or flare was observed in the images taken using the camera units having the light shielding plates of Examples 1 to 6. Thus, it was confirmed that the ghost and flare were suppressed when the ratio (D2/D1) of the second distance D2 to the first distance D1 was 2.5 or more. In particular, in Example 6, compared with Examples 1 to 5, it was confirmed that ghost and flare were more suppressed. In Example 6, compared to Examples 1 to 5, the area of the side surface of the first hole is very small, so that part of the light incident on the lens is reflected from the surface of the lens to the first hole. It is believed that the ghost and flare are further suppressed because the light entering the hole and further being reflected from the first hole toward the lens can be remarkably suppressed. On the other hand, it was confirmed that ghost and flare occurred in the image taken by the camera unit having the light shielding plate of Comparative Example 1.

As described above, according to one embodiment of the light shielding plate, the effects described below can be obtained.
(1) In the light shielding plate 10, the second hole 10H2 has a tapered shape from the front surface 10F toward the rear surface 10R. is likely to be reflected toward the front surface 10F of the light shielding plate 10 at .

(2) Since the ratio (D2/D1) of the second distance D2 between the front surface 10F and the central opening HC to the first distance D1 between the rear surface 10R and the central opening HC is 2.5 or more, It is possible to maintain the size of the two holes 10H2 at a size that allows a tapered shape from the front surface 10F toward the back surface 10R. As a result, it is possible to reduce the amount of light reflected by the side surfaces defining the hole 10H so as to pass through the hole 10H.

(3) When the first inclination angle θ1 in the first region R1 is larger than the inclination angles in each of the second region R2 to the fifth region R5, the diameter of the second hole 10H2 is prevented from becoming excessively large. At the same time, it is possible to make it easier to reflect light toward the surface 10F of the light shielding plate 10 in regions other than the first region R1.

(4) When the first tilt angle θ1 is 50° or more and 60° or less, the surface 10F of the light shielding plate 10 has a It is possible to increase the certainty of reflecting the light towards.

(5) When the fifth tilt angle θ5 of the fifth region R5 is larger than the fourth tilt angle θ4 of the fourth region R4, the fifth tilt angle θ5 of the fifth region R5 is the fourth tilt angle θ5 of the fourth region R4. Expansion of the diameter of the second hole 10H2 is suppressed as compared with the case where the inclination angle is smaller than 4 tilt angles θ4.

(6) From the first region R1 to the fourth region R4, when the inclination angle in each region becomes smaller, the closer to the central opening HC, the more the light incident on the second hole 10H2 becomes It becomes easier to reflect toward 10F.

(7) When the side surface defining the second hole 10H2 has an arcuate shape with the center of curvature positioned outside the light shielding plate 10, the specularly reflected light having the highest brightness among the reflected lights is arcuately shaped. is reflected along the direction toward the surface 10F of the light shielding plate 10 from the side surface having the .

(8) If the side surface defining the first hole 10H1 has an arc shape with the center of curvature positioned outside the light shielding plate 10, the light that enters the hole from obliquely above the front surface 10F It is possible to reduce the amount of light reflected by the side surfaces defining the hole 10H in the vicinity of H1R.

In addition, the embodiment described above can be changed as follows and implemented.
[First hole]
- The side surface defining the first hole 10H1 may have a linear shape in a cross section along a plane perpendicular to the surface 10F. Even in this case, the first hole 10H1 has a shape that tapers from the back surface 10R toward the front surface 10F, the second hole 10H2 has a shape that tapers from the surface 10F toward the back surface 10R, and the first distance If the ratio of the second distance D2 to D1 is 2.5 or more, the effect according to (1) described above can be obtained.

[Second hole]
- The side surface defining the second hole 10H2 may have a linear shape in a cross section along a plane perpendicular to the surface 10F. Even in this case, the first hole 10H1 has a shape that tapers from the back surface 10R toward the front surface 10F, the second hole 10H2 has a shape that tapers from the surface 10F toward the back surface 10R, and the first distance If the ratio of the second distance D2 to D1 is 2.5 or more, the effect according to (1) described above can be obtained.

[Side defining the second hole]
- The inclination angle in each region may decrease in order from the first region R1 toward the fifth region R5. Even in this case, if the ratio of the second distance D2 to the first distance D1 is 2.5 or more, the effect according to (1) described above can be obtained.

- The inclination angle in each region does not have to decrease sequentially from the first region R1 to the fourth region R4. For example, in the first region R1 to the fourth region R4, the tilt angle in each region may be the same as the tilt angle in the other regions. Even in this case, if the ratio of the second distance D2 to the first distance D1 is 2.5 or more, the effect according to (1) described above can be obtained.

- The fifth tilt angle θ5 of the fifth region R5 may be smaller than the fourth tilt angle θ4 of the fourth region R4. Even in this case, if the ratio of the second distance D2 to the first distance D1 is 2.5 or more, the effect according to (1) described above can be obtained.

- The first inclination angle θ1 of the first region R1 may be smaller than 50° or may be larger than 60°. Even in this case, if the ratio of the second distance D2 to the first distance D1 is 2.5 or more, the effect according to (1) described above can be obtained.

- The first tilt angle θ1 of the first region R1 may be smaller than the tilt angle of at least one of the second region R2 to the fifth region R5. Even in this case, if the ratio of the second distance D2 to the first distance D1 is 2.5 or more, the effect according to (1) described above can be obtained.

[Light shielding plate]
- The light shielding plate 10 may be formed from metals other than stainless steel as described above. 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 based alloys is smaller than that of stainless steel. Therefore, the light-shielding plate made of iron-nickel alloy undergoes little deformation due to changes in the outside temperature. It is possible to suppress a change in the incident amount of external light due to a change in . The incident amount of external light is the incident amount of external light that enters the lens through the light shielding plate 10 . Therefore, forming the light shielding plate 10 from an iron-nickel alloy is effective in suppressing ghosts and flares caused by changes in the incident amount of external light.

Note that the iron-nickel alloy is an alloy containing iron and nickel as main components, and containing, for example, 30% by mass or more of nickel and iron as a balance. Among 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 balance of 36% by mass of 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 additive contained in the iron-nickel alloy is 1% by mass or less.

The coefficient of thermal expansion of iron-nickel-cobalt based alloys is smaller than that of iron-nickel based alloys. Therefore, the iron-nickel-cobalt-based alloy light-shielding plate deforms less with changes in the outside temperature, which causes warping of the light-shielding plate itself and deformation of the inner diameter due to thermal expansion and contraction. A change in the incident amount of outside light due to a change in outside air temperature can be further suppressed. Therefore, forming the light shielding plate 10 from an iron-nickel-cobalt alloy is more effective in suppressing ghosts and flares caused by changes in the incident amount of external 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 the balance. alloy. Among the iron-nickel-cobalt alloys, an alloy containing 32% by mass of nickel and 4% by mass to 5% by mass of cobalt, ie, Super Invar, is preferable as a material for forming the light shielding plate 10 . In Super Invar, 32% by mass of nickel and the balance of 4% to 5% by mass of cobalt may contain additives other than iron, which is the main component. Additives are, for example, chromium, manganese, and carbon. The maximum amount of additive contained in the iron-nickel-cobalt alloy is 0.5% by mass or less.

Thus, 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.

(9) It is possible to suppress deformation of the light shielding plate 10 due to changes in the outside temperature, thereby suppressing changes in the incident amount of outside light due to changes in the outside temperature. Therefore, it is possible to suppress the occurrence of ghosts and flares due to changes in the incident amount of external light.

10, 100... light shielding plate, 10F, 10MF, 100F... front side, 10H, 100H... hole, 10H1... first hole, 10H2... second hole, 10M... metal foil, 10MR, 10R, 100R... back side, H1R... back side opening , H2F... Surface opening, HC... Central opening, LN... Lens, MH1... First hole, MH2... Second hole, PMF... Surface protective film, PMR... Back protective film, RF... Surface resist layer, RMF... Surface mask, RMFh, RMRh... Mask hole, RMR... Backside mask, RR... Backside resist layer.

Claims (11)

A metal light shielding plate,
a surface located on the light incident side;
a back surface, which is the surface opposite to the front surface;
a hole penetrating between the front surface and the back surface,
The holes have a rear surface opening on the rear surface, a first hole having a shape tapered from the rear surface to the front surface, and a front surface opening larger than the rear surface opening on the front surface. a second hole having a shape tapered toward the back surface and connected to the first hole;
Among the openings of the first hole, the opening opposite to the back opening is a central opening,
A ratio of the distance between the front surface and the edge of the central opening to the distance between the back surface and the edge of the central opening in the thickness direction of the light shielding plate is 2.5 or more,
In a cross section along a plane orthogonal to the surface, the side surface defining the first hole is arcuate, and the center of curvature of the side surface defining the first hole is positioned outside the light shielding plate.
shading plate. When viewed from the direction facing the surface, the surface opening has a circular shape,
When the side surface defining the second hole is divided into 5 equal parts in the radial direction of the surface opening by circles concentric with respect to the center of the surface opening, when viewed from the direction facing the surface,
In a cross-section along a plane perpendicular to the surface, among the areas obtained by dividing the side surface that divides the second hole into five equal parts , the inclination with respect to the surface in the area including the edge of the surface opening is the same as in other areas 2. The light shielding plate according to claim 1, wherein the inclination of the angle to the surface is larger. In a cross section along a plane perpendicular to the surface, among the areas obtained by dividing the side surface that defines the second hole into five equal parts , the area including the edge of the surface opening has an inclination with respect to the surface of 50° or more and 60°. ° or less. In a cross-section along a plane perpendicular to the surface, among the areas obtained by dividing the side surface that divides the second hole into five equal parts , the inclination with respect to the surface in the area including the edge of the central opening is adjacent to the area. 4. A douser according to claim 2 or 3, which is larger than the inclination with respect to the surface in the mating area. When viewed from the direction facing the surface, the side surface partitioning the second hole is divided into five equal regions . a second region, a third region, a fourth region, and a fifth region;
5. The inclination with respect to the surface of a portion included in each region of the side surfaces defining the second hole decreases from the first region toward the fourth region. The light shielding plate described in . In a cross section along a plane orthogonal to the surface, the side surface defining the second hole is arcuate, and the center of curvature of the side surface defining the second hole is located outside the light shielding plate. 6. The light shielding plate according to any one of 1 to 5. 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 comprising the light shielding plate according to any one of claims 1 to 9 . An electronic device comprising the camera unit according to claim 10 .

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