JP2006317686A - Imaging optical system barrier and imaging unit equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging optical system barrier capable of substantially perfectly preventing the reflection of unwanted light on a surface, where an aperture part is formed, and to provide an imaging unit equipped therewith. <P>SOLUTION: In the imaging optical system barrier 2, at least a part of the surface 4a or 5b, where the aperture part through which light is made to pass when it is at an opening position is formed has a anti-reflection structural body, where structural units having prescribed shape are cyclically arranged in an array state with a pitch smaller than the wavelength of the light that contributes to imaging. At least either the anti-reflection structural body itself or the part of an optical member, where the reflection preventing structural body is provided, comprises a material which can absorb the light that contributes to the imaging. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an imaging optical system barrier and an imaging unit including the same.

  The imaging unit is usually provided with an imaging optical system barrier for protecting the surface of a lens or mirror incorporated in the imaging unit.

  In general, the imaging optical system barrier is often configured in a plate shape, and can be opened and closed between a closed position that blocks the optical path of light traveling inside the imaging unit and an open position that opens the optical path. Move to slide. The imaging optical system barrier forms an opening when in the open position, and the light that has passed through the opening reaches the lens or the mirror.

  However, in the conventional imaging unit incorporating the imaging optical system barrier, there is a gap for interposing the imaging optical system barrier between the opening portion of the front cover for makeup and the imaging lens, so it is unnecessary to enter the imaging unit. There is a problem that flare may be formed by reflection of light within the imaging unit.

  In order to solve this problem, for example, Patent Document 1 describes an imaging unit having an uneven pattern for preventing flare on the outer surface of an imaging optical system barrier. The concavo-convex pattern is a large number of concentric concavo-convex concavo-convex patterns, mosaic shapes, or satin-like shapes, and shields unnecessary light that reaches the concavo-convex pattern from incident light incident from the opening formed by the front cover for makeup, Flare formation can be effectively prevented by the hood effect.

  Further, in the conventional imaging unit described in Patent Document 1, the opening formed by the imaging optical system barrier has a tapered shape whose inner peripheral surface has a larger diameter toward the inside. As a result, it is possible to prevent light incident obliquely from entering the imaging lens by being reflected by the opening, and more effectively to prevent flare formation.

As described above, the conventional imaging unit described in Patent Document 1 effectively prevents the formation of flare by providing an uneven pattern on the outer surface of the imaging optical system barrier or by inclining the opening. be able to.
Japanese Patent Laid-Open No. 9-43678

  However, the conventional imaging optical system barrier described in Patent Document 1 can effectively prevent the formation of flare by reducing the reflection of unnecessary light, but substantially completely absorbs the unnecessary light that arrives. Can not do it. For this reason, the problem that the image quality is deteriorated due to the generation of stray light and the formation of flare and ghost still remains.

  Therefore, an object of the present invention is to provide an imaging optical system barrier that can substantially completely prevent reflection of unnecessary light on a surface that forms an opening, and an imaging unit including the same.

  The present invention provides an imaging optical system barrier that is provided in an imaging unit and moves between an open position and a closed position, and in the open position, a surface that forms an opening for allowing light to pass through, and an opening An antireflection structure provided on at least a part of the surface to be formed, in which structural units having a predetermined shape are periodically arranged in an array at a pitch smaller than the wavelength of light contributing to imaging At least one of the structure itself and the portion provided with the antireflection structure of the optical member is made of a material that can absorb light contributing to imaging.

  Moreover, the antireflection structure is formed on the sheet, and the sheet may be attached to at least a part of the surface forming the opening. As an example, the sheet is made of a material that can absorb light contributing to imaging. As another example, the sheet is made of a transparent material, and the imaging optical system barrier to which the sheet is attached is made of a material that can absorb light contributing to imaging.

  Preferably, the difference between the refractive index of the sheet and the refractive index of the base material constituting the imaging optical system barrier is 0.1 or less. Further, the difference between the refractive index of the adhesive for bonding the sheet and the base material constituting the imaging optical system barrier and the refractive index of the sheet is 0.1 or less, and the refractive index of the adhesive, The difference from the refractive index of the substrate may be 0.1 or less.

  Preferably, the structural unit of the antireflection structure has at least a pitch or more, more preferably, a height or depth that is at least three times the pitch. Preferably, the structural unit of the antireflection structure has a substantially conical protruding shape and / or a substantially conical depressed structure. Preferably, the bottom shape of the antireflection structure is one selected from the group consisting of a substantially circular shape, a substantially rectangular shape, and a substantially regular hexagonal shape.

  The material capable of absorbing the light contributing to the imaging may contain, for example, a dye for absorbing the light contributing to the imaging, and the pigment for absorbing the light contributing to the imaging. It may be.

  Further, the material may be a black material. In that case, the black material may contain a dye or may contain a pigment.

  Preferably, the surface forming the opening has an inclination with a larger diameter toward the imaging surface.

  Moreover, this invention is an imaging unit provided with the imaging optical system barrier of Claim 1.

  ADVANTAGE OF THE INVENTION According to this invention, the imaging optical system barrier which can prevent reflection of the unnecessary light in the surface which forms an opening part substantially completely, and an imaging unit provided with the same can be provided.

(First embodiment)
FIG. 1 is a perspective view of an imaging unit 1 including an imaging optical system barrier according to the first embodiment of the present invention. The imaging unit may be, for example, an imaging device such as a digital still camera or a film camera, or may be used by being incorporated in a portable terminal having an imaging function.

  In FIG. 1, an imaging unit 1 includes an imaging optical system barrier 2 and an imaging lens (not shown). The imaging lens is disposed inside the imaging unit 1. The imaging optical system barrier 2 has a plate shape, for example, and is provided at a position that blocks light incident on the imaging lens.

  The imaging optical system barrier 2 includes an upper imaging optical system barrier 2a and a lower imaging optical system barrier 2b. The imaging optical system barriers 2a and 2b form an opening when in the open position. In the following description, when it is not necessary to distinguish between the imaging optical system barriers 2a and 2b, they are collectively referred to as the imaging optical system barrier 2.

  The imaging optical system barrier 2 is made of a material that can absorb light contributing to imaging. The light that contributes to imaging is light that the imaging member built in the imaging unit is exposed to. In this embodiment, the imaging optical system among the light in the visible band wavelength (hereinafter referred to as visible light). The light reflected by the surface forming the opening of the barrier 2 shall be said.

  2A is a partially enlarged view showing a cross section of the housing of the imaging unit 1 shown in FIG. 1, and shows a case where the imaging optical system barriers 2a and 2b are in the closed position. As illustrated in FIG. 2A, an imaging optical system barrier 2 a and an imaging optical system barrier 2 b are disposed inside the exterior member 3 that is a housing of the imaging unit 1. The imaging optical system barriers 2a and 2b are driven to slide by a predetermined mechanism (not shown), and open and close according to the imaging state and the storage state. Here, the imaging state means that the imaging optical system barrier 2 is in the open position and an opening is formed. One storage state means that the imaging optical system barrier 2 is in the closed position and no opening is formed.

  One of the major features of the present invention is that the imaging optical system barriers 2a and 2b have an antireflection structure having a specific structure on at least a part of the surfaces 4a and 4b forming the openings. Thus, unnecessary light in visible light is sufficiently prevented from being reflected, and incident unnecessary light can be absorbed substantially completely.

  2B is a partially enlarged view showing a cross section of the housing of the imaging unit 1 shown in FIG. 1, and is a diagram showing a case where the imaging optical system barriers 2a and 2b are in the open position. In FIG. 2B, the light 5 traveling into the imaging unit 1 is indicated by a solid arrow. Here, in the conventional imaging unit, when light reaches the surface 4a or 4b of the imaging optical system barrier 2 forming the opening, the light is reflected by the surface 4a or 4b and reaches the imaging lens (unnecessary light 6). ). In this case, since flare and ghost are formed, there is a problem that video quality is deteriorated.

  However, the imaging optical system barrier 2 according to the present embodiment is made of a material capable of absorbing visible light, and has an antireflection structure on at least a part of the surfaces 4a and 4b forming the openings. The unnecessary light in the visible light can be sufficiently prevented from being reflected, and the incident unnecessary light can be substantially completely absorbed. Therefore, the generation of stray light due to reflection can be reduced on the surfaces 4a and 4b.

  FIG. 3 is an enlarged view of the imaging optical system barrier 2b shown in FIGS. 2A and 2B. In FIG. 3, an antireflection structure 7 is formed on a base material 8 constituting the imaging optical system barrier 2b. In FIG. 3, the imaging optical system barrier 2 b is illustrated as an example, but the imaging optical system barrier 2 a is also anti-reflective on at least a part of the surface 4 a that forms the opening, similarly to the imaging optical system barrier 2 b. It has a structure.

  The antireflection structure is a wavelength (usually approximately about a wavelength of unnecessary light (light that is reflected by the imaging optical system barrier 2a or 2b and reaches the imaging lens) in the visible light in a structural unit having a predetermined shape. 400-700 nm) and periodically arranged in an array. Preferably, the structural units are periodically arranged in an array at a pitch smaller than the lower limit value of the wavelength of unnecessary light, that is, a pitch smaller than the shortest wavelength of visible light. By periodically arranging the structural units having a predetermined shape in an array, the apparent refractive index is continuously changed for visible light, and the transmission / reflection characteristics at the interface with the air layer It is possible to form an antireflection functional surface with little incidence angle dependency and wavelength dependency.

  In addition, the said pitch means the pitch in the densest arrangement direction, when the reflection preventing structure is comprised by the two-dimensional arrangement | sequence of many fine structure units.

  The antireflection structure means a member having a fine structure formed on the surface in order to prevent reflection of unnecessary light whose reflection should be reduced, and only an aspect that does not completely reflect unnecessary light whose reflection should be reduced. Rather, it includes an aspect having an effect of preventing reflection of unnecessary light that should reduce reflection at a predetermined wavelength.

  As an antireflection structure that can be used in the present embodiment, for example, conical protrusions having a height H1 as shown in the schematic enlarged view of FIG. 4A are used as structural units, and these conical protrusions have a pitch P1 and a period. In particular, there are structures arranged in an array.

  The pitch P1 of the structural unit is substantially constant in one arrangement direction in the antireflection structure and may be smaller than the shortest wavelength of visible light, but the incident angle dependence and wavelength of transmission / reflection characteristics at the interface From the viewpoint that the dependency can be further reduced, the pitch P1 is preferably ½ or less, more preferably ３ or less of the shortest wavelength of visible light. For example, considering the manufacturability of the antireflection structure as described later, it is desirable that the pitch P1 has a certain size, and is usually about 1/10 or more of the shortest wavelength of visible light.

  The height H1 of the structural unit is not particularly limited, and the height H1 of all the structural units in the antireflection structure does not necessarily have to be constant, but the higher the height H1, the more visible light is generated. There is an advantage that the antireflection function for unnecessary light is improved. Accordingly, the height H1 of the structural unit is at least the pitch P1 or more (the minimum structural unit height is at least the pitch), and at least three times the pitch P1 (the minimum structural unit height is three times the pitch). Or more). In view of the manufacturability of the antireflection structure as described later, for example, it is desirable that the height H1 is up to a certain size, and usually not more than about 5 times the pitch P1 (the maximum structural unit). The height is preferably about 5 times or less of the pitch.

  In the present embodiment, as described above, the antireflection structure 7 may be a structure having a structural unit of, for example, a conical shape (FIG. 4A). In this case, for example, an antireflection structure 7 having a pitch of 0.15 μm and a height of 0.15 μm may be formed. This corresponds to a structural unit having a pitch smaller than the visible band wavelength and a height equal to or higher than the pitch.

  However, the structural unit of the antireflection structure 7 is not necessarily limited to the conical structure shown in FIG. 4A. For example, the structure of a pyramid shape (FIG. 4B) such as a regular hexagonal pyramid shape or a quadrangular pyramid shape. It may be a body. Further, the shape of such a structural unit is not necessarily limited to a cone shape, and even if it is a bell shape (FIGS. 5A and 5B) with a rounded tip, a truncated cone shape (FIG. 6A) or a truncated pyramid shape A frustum shape such as (FIG. 6B) may be used. Moreover, each structural unit does not need to be a strict geometric shape, and may be substantially a cone shape, a bell shape, a frustum shape, or the like.

  Furthermore, in FIG. 4 to FIG. 6, the structural unit has a protruding shape as the antireflection structure, but in the present embodiment, the structure unit is not limited to such a protruding shape. It is also possible to use an antireflection structure in which concavities such as cones, bells, and frustums are arranged in an array periodically with a pitch smaller than the shortest wavelength of visible light. It is. When the structural unit of the antireflection structure has a depressed shape, the depth of the structural unit may be determined in the same manner as the height H1 of the protruding structural unit described above. Further, the projecting-shaped structural unit and the depressed-shaped structural unit may be simultaneously present in one antireflection structural body. In addition, in the case of an antireflection structure in which such a projecting shape structural unit and a depressed shape structural unit exist at the same time, the sum of the height of the projected portion and the depth of the depressed portion is within the range of the height H1. Is preferred. As described above, in the antireflection structure used in the present embodiment, each structural unit is periodically arranged in an array at a pitch smaller than the shortest wavelength of visible light, and can sufficiently prevent reflection of unnecessary light. If possible, the shape of the structural unit is not particularly limited.

  In the present embodiment, the refractive index of visible light continuously changes at the air interface, and reflection of unnecessary light can be more sufficiently prevented. Alternatively, it is preferable to use an antireflection structure having a substantially conical depression shape. When the substantially conical shape is a substantially regular hexagonal pyramid shape, the structural units are arranged with a high filling factor, and visible light is refracted at the air interface. This is particularly preferable from the viewpoint of further improving the visible light transmission characteristics such that the rate changes continuously.

  A material that can absorb visible light and that constitutes the imaging optical system barrier 2 is not particularly limited as long as it can absorb visible light having a wavelength of about 400 to 700 nm. For example, a black material is preferably used. Can be used. Such black materials include, for example, black dyes obtained by mixing pigments such as cyan, magenta, and yellow in resins such as polycarbonate resins and acrylic resins (for example, Plaster Black 8950, Plaster Black 8970 (both trade names, Arimoto Chemical Industry Co., Ltd.)) or a pigment such as carbon black.

  The imaging optical system barrier 2 used in the present embodiment has the antireflection structure 7 on at least a part of the surfaces 4a and 4b forming the openings. Of course, the entire surfaces of the surfaces 4a and 4b are formed. You may have an antireflection structure.

  The method for manufacturing the imaging optical system barrier 2 is not particularly limited, but as an example, for example, a pattern is drawn on a quartz glass substrate or the like by a method such as electron beam drawing, and dry etching or the like is performed, and an antireflection structure is previously provided. After forming a high-precision master mold that has been precisely machined to the same shape as No. 7, a glass mold for forming an antireflection structure is produced by press-molding a heat-softened glass material using the master mold. For example, there is a method in which a material capable of absorbing visible light such as the black material (black resin) is subjected to press molding using the antireflection structure molding die. When such a method is employed, the imaging optical system barrier 2 having the antireflection structure 7 on at least a part of the surfaces 4a and 4b can be manufactured at a low cost and in large quantities.

  In addition to the above, when manufacturing the imaging optical system barrier 2 used in this embodiment, for example, a metal such as aluminum, brass, stainless steel, copper, or other alloy is used as a material, and cutting or press molding is performed. It is also possible to manufacture by a method, or it is possible to manufacture by a method of appropriately combining etching, X-ray lithography, photolithography and the like.

  Further, in the imaging optical system barriers 2a and 2b, the surfaces 4a and 4b forming the opening have an inclination with a large diameter toward the imaging surface. Thereby, even if there is very little reflected light that is not absorbed by the surfaces 4a and 4b, it can be reflected in a direction that is difficult to enter the imaging lens, and stray light can be suppressed.

(Second Embodiment)
The basic configuration of an imaging unit including an imaging optical system barrier according to this embodiment is the same as that of the first embodiment, but an antireflection structure having at least a part of a surface forming an opening of the imaging optical system barrier And the structure of the material which can absorb visible light is different from 1st Embodiment.

  FIG. 7 is an enlarged cross-sectional view of the imaging optical system barrier 2b according to the present embodiment. In FIG. 7, a sheet 19 having an antireflection structure 17 is stuck on a base material 18 constituting the imaging optical system barrier 4b. In FIG. 7, the imaging optical system barrier 2 b is illustrated as an example, but the imaging optical system barrier 2 a is also provided with an antireflection structure on at least a part of the surface 4 a forming the opening, similarly to the imaging optical system barrier 2 b. A sheet 19 having a body 17 is affixed.

  The base material 18 constituting the imaging optical system barrier 2 has a size including a desired light beam to be absorbed, a mechanical strength, and a thickness necessary for the configuration, and normally absorbs visible light having a wavelength of about 400 to 700 nm. If it is the material which can do, there will be no limitation in particular, For example, a black material can be used suitably. The antireflection structure 17 and the base material 18 correspond to the antireflection structure 7 and the base material 8 in the first embodiment, and thus detailed description thereof is omitted. Also in the present embodiment, as in the first embodiment, a case where the light contributing to imaging is visible light will be described as an example.

  As in the first embodiment, the black material is a black dye obtained by mixing a pigment such as cyan, magenta, or yellow in a base material such as polycarbonate resin or acrylic resin (for example, Plaster Black 8950, Plaster Black 8970). (All are trade names, manufactured by Arimoto Chemical Co., Ltd.)) and pigments such as carbon black.

  The sheet 19 is made of, for example, a transparent material such as an acrylic resin, and has an antireflection structure 7 formed on at least a part of the surface thereof at a pitch smaller than the wavelength of visible light. The thickness of the sheet 19 is not limited as long as it is easy to handle and sufficient mechanical strength can be obtained, but is preferably 10 μm or more.

  The height and pitch of the antireflection structure 17 may be determined in the same manner as in the first embodiment. For example, when using visible light, a pitch of 0. 0 is formed on the sheet 19 as shown in FIG. 4A, for example. A conical antireflection structure 17 having a size of 15 μm and a height of 0.15 μm may be formed on the sheet 19. This corresponds to a structural unit having a pitch smaller than the visible band wavelength and a height equal to or higher than the pitch.

  Although the manufacturing method of the sheet 19 having the antireflection structure 17 is not particularly limited, the sheet 19 can be manufactured as follows, for example. For example, a pattern is drawn on a quartz glass substrate or the like by a method such as electron beam drawing and processing such as dry etching is performed, and after forming a high-precision master mold that has been precisely processed into the same shape as the antireflection structure 17 in advance, The master mold is used to produce a glass antireflection structure molding die by press molding a heat-softened glass material, and the antireflection structure molding die is used, for example, for the acrylic resin or the like. For example, the material may be subjected to press molding. When such a method is adopted, the sheet 19 having the antireflection structure 7 at least in part can be manufactured at a low cost and in large quantities.

  The acrylic resin used for press molding preferably has a thickness of about 10 μm or more (the thickness of the sheet 19 +0.15 μm) from the viewpoint of ease of handling and mechanical strength. Thereby, the sheet | seat 19 which is easy to handle and has sufficient mechanical strength can be manufactured.

  As described above, according to the present embodiment, unnecessary visible light incident thereon can be obtained by attaching a sheet having the antireflection structure 17 to the surface of the base material 18 made of a material capable of absorbing visible light. Reflection at the interface with air can be sufficiently prevented, and incident unnecessary visible light can be absorbed substantially completely. Therefore, an antireflection function can be imparted to the target structure at low cost and easily.

  Further, in the present embodiment, the sheet material is described as being an acrylic resin, but the sheet material is not limited to this, for example. A polycarbonate resin, a polyethylene terephthalate resin, etc. can also be used.

  In the present embodiment, a transparent material is used as the material of the sheet, but the material is not necessarily limited to the transparent material, and is colored black by a material that can absorb visible light, for example, a dye or a pigment. A black material may be used. By using a sheet made of a material that can absorb visible light, the light beam absorption efficiency can be further improved. When the sheet is made of a material that can absorb visible light, the imaging optical system barrier to which the sheet is attached does not necessarily need to be made of a material that can absorb visible light.

  In the present embodiment, the case where a structural unit having a conical shape (for example, FIG. 4A) is used as an example of the antireflection structure has been described as an example. However, as in the case of the first embodiment, the antireflection structure is used. The structural unit is not necessarily limited to such a structure. For example, the structural unit may be a structure having a regular hexagonal pyramid shape or a pyramid shape such as a quadrangular pyramid shape (FIG. 4B). Further, the shape of such a structural unit is not necessarily limited to a cone shape, and even if it is a bell shape (FIGS. 5A and 5B) with a rounded tip, a truncated cone shape (FIG. 6A) or a truncated pyramid shape A frustum shape such as (FIG. 6B) may be used. Moreover, each structural unit does not need to be a strict geometric shape, and may be substantially a cone shape, a bell shape, a frustum shape, or the like. As in the first embodiment, the structural unit of the antireflection structure may be a protruding shape, or may be a depressed shape.

  Note that the difference between the refractive index of the sheet and the refractive index of the base material constituting the imaging optical system barrier is preferably 0.1 or less. Thereby, the reflectance in the interface of the sheet | seat and the base material which comprises an imaging optical system barrier can be made into a preferable low value.

  In addition, when the sheet and the substrate are bonded using an adhesive, the difference between the refractive index of the sheet and the refractive index of the adhesive, and the difference between the refractive index of the substrate and the refractive index of the adhesive are both 0. It is preferable that it is 1 or less. Thereby, both the reflectance at the interface between the sheet and the adhesive and the reflectance at the interface between the adhesive and the base material can be set to preferable low values. If the sheet having an antireflection structure is made of a material that can absorb light contributing to imaging, such as a black material, and the sheet can absorb unnecessary light substantially completely, the sheet is refracted. The difference between the refractive index and the refractive index of the adhesive only needs to be 0.1 or less, and the difference between the refractive index of the substrate and the refractive index of the adhesive does not necessarily have to be 0.1 or less.

  In the first and second embodiments, light having a substantially visible band wavelength is described as an example of light contributing to imaging, but the present invention is not limited to this. In addition to visible light, ultraviolet light (ultraviolet band wavelength: 150 nm to 400 nm), near infrared light (near infrared band wavelength: 700 nm to 2 μm), and far infrared light (far infrared band wavelength: 2 μm to 13 μm) Can be used. Also in this case, the pitch P1 of the structural units in the antireflection structure is formed with a pitch smaller than the shortest wavelength of each light. Further, the height H1 of the structural unit is equal to or greater than the pitch P1 (the minimum structural unit height is equal to or greater than the pitch), and at least three times the pitch P1 (the minimum structural unit height is equal to or greater than three times the pitch). ) Is preferable.

  In the first and second embodiments, the case where the imaging optical system barrier moves up and down has been described as an example. However, the shape of the imaging optical system barrier is not limited to this, and the imaging optical system barrier may move left and right. Good. Furthermore, the imaging optical system barrier is not limited to one that moves linearly, and may be one that rotates relative to the center of rotation, for example.

  ADVANTAGE OF THE INVENTION According to this invention, the imaging optical system barrier which can prevent reflection of the unnecessary light in the surface which forms an opening part substantially completely, an imaging unit provided with the same, etc. are provided.

The perspective view of the imaging unit 1 provided with the imaging optical system barrier which concerns on the 1st Embodiment of this invention. It is the elements on larger scale which show the section of the case of image pick-up unit 1 shown in Drawing 1, and shows the case where image pick-up optical system barriers 2a and 2b are in a closed position. It is the elements on larger scale which show the section of the case of imaging unit 1 shown in Drawing 1, and shows the case where imaging optical system barriers 2a and 2b are in an open position. Enlarged view of the imaging optical system barrier 2b shown in FIGS. 2A and 2B It is a schematic enlarged view which shows an example of this antireflection structure 7, and is a figure of a structure whose structural unit is a cone shape FIG. 4 is a schematic enlarged view showing an example of the antireflection structure 7 and is a diagram of a structure in which the structural unit is a pyramid shape. It is a schematic enlarged view showing an example of the antireflection structure 7, and is a diagram of a structure in which the structural unit is a bell-shaped structure It is a schematic enlarged view showing an example of the antireflection structure 7, and is a diagram of a structure in which the structural unit is a bell-shaped structure FIG. 5 is a schematic enlarged view showing an example of the antireflection structure 7, and is a diagram of a structure in which the structural unit is a truncated cone shape. FIG. 4 is a schematic enlarged view showing an example of the antireflection structure 7, and is a diagram of a structure in which the structural unit is a truncated pyramid shape. The expanded sectional view of the imaging optical system barrier 2b which concerns on the 2nd Embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Imaging unit 2 Imaging optical system barrier 3 Exterior member 4 Surface 5 Light 6 Unnecessary light 7, 17 Antireflection structure 8, 18 Base material 19 Sheet

Claims (17)

An imaging optical system barrier provided in the imaging unit and moving between an open position and a closed position,
A surface forming an opening for passing light in an open position;
An antireflection structure provided on at least a part of a surface forming the opening and having a structural unit having a predetermined shape periodically arranged in an array at a pitch smaller than the wavelength of light contributing to imaging. Prepared,
At least one of the antireflection structure itself and a portion of the optical member provided with the antireflection structure is made of a material capable of absorbing light that contributes to the imaging. System barrier. The antireflection structure is formed on a sheet;
The imaging optical system barrier according to claim 1, wherein the sheet is attached to at least a part of a surface forming the opening.   The imaging optical system barrier according to claim 2, wherein the sheet is made of a material capable of absorbing light contributing to the imaging.   The imaging optical system according to claim 2, wherein the sheet is made of a transparent material, and the imaging optical system barrier to which the sheet is attached is made of a material capable of absorbing light contributing to the imaging. barrier.   The imaging optical system barrier according to claim 2, wherein a difference between a refractive index of the sheet and a refractive index of a base material constituting the imaging optical system barrier is 0.1 or less.   The difference between the refractive index of the adhesive for bonding the sheet and the base material constituting the imaging optical system barrier and the refractive index of the sheet is 0.1 or less, and the refractive index of the adhesive, The imaging optical system barrier according to claim 2, wherein a difference from the refractive index of the substrate is 0.1 or less.   The imaging optical system barrier according to claim 1, wherein the structural unit of the antireflection structure has a height or depth of at least a pitch or more.   The imaging optical system barrier according to claim 1, wherein the structural unit of the antireflection structure has a height or a depth that is at least three times the pitch.   The imaging optical system barrier according to claim 1, wherein the structural unit of the antireflection structure has a substantially conical protruding shape and / or a substantially conical depressed structure.   The imaging optical system barrier according to claim 1, wherein the bottom surface shape of the antireflection structure is one selected from the group consisting of a substantially circular shape, a substantially rectangular shape, and a substantially regular hexagonal shape.   The imaging optical system barrier according to claim 1, wherein the material capable of absorbing light contributing to imaging includes a dye for absorbing light contributing to imaging.   The imaging optical system barrier according to claim 1, wherein the material capable of absorbing light contributing to imaging includes a pigment for absorbing light contributing to imaging.   The imaging optical system barrier according to claim 1, wherein the material is a black material.   The imaging optical system barrier according to claim 13, wherein the black material contains a dye.   The imaging optical system barrier according to claim 13, wherein the black material contains a pigment.   2. The imaging optical system barrier according to claim 1, wherein a surface forming the opening has an inclination with a larger diameter toward the imaging surface. An imaging unit comprising the imaging optical system barrier according to claim 1.

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