阅读说明：本技术 树脂制品、制造树脂制品的方法、可更换镜头和光学装置 (Resin article, method of manufacturing resin article, interchangeable lens, and optical apparatus ) 是由 名古屋利光 小岛诚 及川圭 榎田弓贵也 远藤隆史 森崎修 于 2019-07-25 设计创作，主要内容包括：本公开涉及一种包括抗反射表面的树脂制品,该树脂制品包括多个第一凹入部分、多个第二凹入部分和部件表面。第一凹入部分的开口宽度等于或大于1μm且等于或小于300μm。第二凹入部分形成在多个第一凹入部分中的每个第一凹入部分上,并且开口宽度等于或大于10nm且等于或小于1μm。部件表面构造成围绕多个第一凹入部分中的每个第一凹入部分。本公开还涉及一种制备树脂制品的方法、可更换镜头、光学装置。(The present disclosure relates to a resin article including an antireflection surface, the resin article including a plurality of first concave portions, a plurality of second concave portions, and a component surface. The opening width of the first concave portion is equal to or greater than 1 μm and equal to or less than 300 μm. The second concave portion is formed on each of the plurality of first concave portions, and the opening width is equal to or greater than 10nm and equal to or less than 1 μm. The component surface is configured to surround each of the plurality of first recessed portions. The present disclosure also relates to a method of producing a resin article, an interchangeable lens, and an optical apparatus.)

1. A resin article comprising an antireflective surface, the antireflective surface comprising:

a plurality of first concave portions having an opening width equal to or greater than 1 μm and equal to or less than 300 μm;

a plurality of second concave portions which are formed on each of the plurality of first concave portions and have an opening width of 10nm or more and 1 μm or less, an

A component surface configured to surround each of the plurality of first recessed portions.

2. The resin article according to claim 1, wherein a ratio of an area of the first concave portion to an area of the antireflection surface is equal to or greater than 10% and equal to or less than 95%.

3. The resin article according to claim 1 or 2, wherein a shortest distance among distances each measured between two adjacent first concave portions of the plurality of first concave portions is equal to or less than 100 μm.

4. The resin article according to claim 1 or 2, wherein a ratio of any one of the opening widths of the plurality of first concave portions to a corresponding one of depths of the first concave portions is equal to or greater than 0.4.

5. The resin article of claim 1 or 2, wherein the component surface comprises a free surface, and

wherein the free surface is formed so that the free surface does not contact a mold for molding the resin article.

6. The resin article according to claim 5, wherein the component surface has a curved convex surface.

7. The resin article according to claim 1 or 2, wherein the antireflection surface is made of a resin material, and

wherein the resin material contains a filler.

8. The resin article according to claim 7, wherein a ratio of the content of the filler to the resin material is equal to or more than 5 mass% and equal to or less than 45 mass%.

9. The resin article according to claim 7, wherein a diameter of each particle of the filler is equal to or greater than 20 μm and equal to or less than 80 μm, and a length of each particle of the filler is equal to or greater than 70 μm and equal to or less than 100 μm.

10. The resin article according to claim 1 or 2, wherein the surface roughness of the component surface is represented by an Spc value, and

wherein the Spc value of the surface of the part is equal to or greater than 1500 and equal to or less than 9000.

11. A method of making a resin article comprising an antireflective surface, the method comprising:

preparing a mold, a molding surface of which includes a plurality of first convex portions and a plurality of second convex portions, the plurality of second convex portions being formed on surfaces of the plurality of first convex portions, a diameter of the plurality of first convex portions being equal to or larger than 1 μm, a diameter of the plurality of second convex portions being equal to or larger than 10nm and equal to or smaller than 1 μm; and

forming a plurality of first concave portions on a resin material by bringing the resin material into contact with the mold, the plurality of first concave portions having opening widths equal to or greater than 1 μm and equal to or less than 300 μm, and forming a plurality of second concave portions having opening widths equal to or greater than 10nm and equal to or less than 1 μm on inner surfaces of the plurality of first concave portions.

12. The method according to claim 11, wherein the forming of the plurality of first concave portions and the plurality of second concave portions includes controlling a transfer pressure so that a ratio of an area of the plurality of first concave portions to an area of the antireflection surface is equal to or greater than 10% and equal to or less than 95%.

13. The method according to claim 11 or 12, wherein the forming of the plurality of first concave portions and the plurality of second concave portions includes controlling transfer pressure so that a shortest distance among distances each measured between two adjacent first concave portions of the plurality of first concave portions is equal to or smaller than 100 μm.

14. The method according to claim 11 or 12, wherein the forming of the plurality of first concave portions and the plurality of second concave portions includes controlling a transfer pressure so that a ratio of any one of the opening widths of the plurality of first concave portions to a corresponding one of depths of the first concave portions is equal to or greater than 0.4.

15. The method of claim 11 or 12, wherein the forming of the plurality of first concave portions and the plurality of second concave portions comprises controlling a transfer pressure such that a space is formed between the plurality of first convex portions and the molding surface, and

wherein the space prevents the molding surface and the resin material from contacting each other.

16. The method of claim 11 or 12, wherein the forming of the plurality of first recessed portions and the plurality of second recessed portions comprises using a resin material including a filler.

17. The method of claim 11 or 12, wherein the preparing of the mold comprises attaching the mold to an injection molding apparatus.

18. The method of claim 11 or 12, wherein the preparing of the mold comprises attaching the mold to a roll-molding apparatus.

19. An interchangeable lens, comprising:

a support member comprising the resin article according to claim 1, and

an optical element supported on an optical axis by the support member.

20. An optical device, the optical device comprising:

a container comprising the resin article of claim 1, an

An optical system housed by the container.

Technical Field

The present invention relates to a resin article including an antireflection surface, a method of producing the resin article, an interchangeable lens, and an optical apparatus.

Background

Various optical devices include a light shielding member to reduce stray light. Stray light is scattered light generated near the optical path of the optical device and affects the performance of the optical device. Therefore, the light shielding member is provided to absorb or reduce stray light. For example, stray light generated in an imaging device such as a camera may cause image degradation including degraded contrast, ghosting, and flashing. In addition, in a measuring device such as a reflectometer, stray light may cause measurement errors, thereby impairing the reliability of the measured value. Therefore, it is desirable to reduce stray light in the optical device as much as possible. Preferably, the light shielding member has an antireflection property to absorb stray light from its surface and reduce the scattered light to almost zero.

Conventionally, a technique of reducing stray light by forming an antireflection surface on a light shielding member is known. For example, in one technique, a black material is used for the inner surface of a lens barrel of a projector or a camera, or the inner surface is coated with a black paint. In addition, since the black material or black coating may not sufficiently reduce scattered light generated from incident light having a large incident angle, the surface of the light shielding member may be roughened as necessary by using a method such as sand blasting to reduce the scattered light.

In another technique, a low refractive layer and a high refractive layer are laminated on a light shielding member to reduce surface reflection by light interference. In addition, an antireflection surface having a moth-eye structure is attracting attention recently because the structure reduces surface reflection more sufficiently than using light interference. In the moth-eye structure, the refractive index of the light-shielding member is smoothly distributed by forming a fine rough surface on the light-shielding member. On the fine rough surface, fine concave-convex portions each smaller than the wavelength of visible light are formed.

In the antireflective fine rough surface having a moth-eye structure, fine concave and convex portions are regularly arranged with a pitch preferably equal to or smaller than the wavelength of incident light. For example, each of the fine projecting portions of the fine rough surface stands vertically on the base, and the cross-sectional area of each of the fine projecting portions gradually decreases as each of the projecting portions extends toward the front end portion thereof. Therefore, since the refractive index of each convex portion changes gently at the interface of each convex portion, reflection on the antireflection surface is reduced, thereby achieving low reflectance of the antireflection surface.

Moth-eye structures are very effective in reducing surface reflection, and therefore the structures are used in components of various optical devices, such as displays, imaging devices, illumination devices, and projectors. Japanese patent application laid-open No.2015-184428 describes a technique that achieves higher antireflection performance and better antireflection effect for obliquely incident light. In this technique, fine protrusions are formed on the wavy portion. The waves are large and smooth and have a pitch of about 100 to 600 μm. The fine protrusions are formed at a pitch equal to or smaller than the wavelength of visible light.

Japanese patent application laid-open No.2009-128538 describes a technique of forming a special surface shape by using a dry etching method. In this surface shape, a plurality of fine concave-convex portions are formed on the rough surface. The rough surface has a surface roughness larger than a predetermined wavelength, and the plurality of fine concave-convex portions have an average pitch equal to or smaller than the predetermined wavelength.

However, in the structure described in japanese patent application laid-open No.2015-184428, when the antireflection surface is wiped for cleaning, fine protrusions on the antireflection surface may be damaged, thereby reducing the antireflection effect. Therefore, the antireflection surface has a problem in durability. In particular, in a design intended to obtain high antireflection performance, concave portions or convex portions of a fine rough surface tend to have sharp edges or become finer. This design makes the corresponding article fragile and brittle and is prone to dust generation in fine rough surfaces. Therefore, there is a problem that the antireflection fine rough surface having a moth-eye structure is difficult to be used in an interior of an optical device where dust is not desired to be generated, for example, on a lens barrel or a body of a camera. Another problem is that it is difficult to achieve both the antireflection performance and the durability because the antireflection performance becomes insufficient if the durability is improved.

In the treatment method described in japanese patent application laid-open No.2009-128538, the complicated treatment makes the production time and cost unacceptable. In addition, not only the method of japanese patent application laid-open No.2009-128538 but also other methods of forming a special surface shape for realizing a high-performance light shielding member also tend to increase production time and cost. In contrast, if the surface of the light-shielding member is formed by using a method involving a short production time and low cost (e.g., sandblasting), the light-shielding performance may become insufficient.

For this reason, an article comprising an antireflection surface that can be simply manufactured at low cost, has good durability, generates less dust, and has good antireflection performance is desired.

Disclosure of Invention

According to a first aspect of the present invention, a resin article includes an antireflection surface including a plurality of first concave portions having an opening width of equal to or more than 1 μm and equal to or less than 300 μm, a plurality of second concave portions formed on each of the plurality of first concave portions and having an opening width of equal to or more than 10nm and equal to or less than 1 μm, and a member surface configured to surround each of the plurality of first concave portions.

According to a second aspect of the present invention, a method of making a resin article comprising an antireflective surface comprises: preparing a mold having a molding surface including a plurality of first convex portions having a diameter of 1 μm or more and a plurality of second convex portions having a diameter of 10nm or more and 1 μm or less formed on a surface of the plurality of first convex portions; and forming a plurality of first concave portions on the resin material and a plurality of second concave portions on inner surfaces of the plurality of first concave portions by bringing the resin material into contact with the mold, the plurality of first concave portions having opening widths equal to or greater than 1 μm and equal to or less than 300 μm, the plurality of second concave portions having opening widths equal to or greater than 10nm and equal to or less than 1 μm.

Other features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

Drawings

Fig. 1A is a perspective view schematically showing an antireflection portion of one embodiment of the present invention.

Fig. 1B is a cross-sectional view schematically illustrating an antireflection portion of one embodiment of the present invention.

Fig. 2 is a sectional view in which a portion of fig. 1B is enlarged.

Fig. 3 is a perspective view in which a portion of fig. 1A is enlarged.

Fig. 4 is a plan view of a resin member of an embodiment of the present invention.

Fig. 5 is a plan view in which a portion of fig. 4 is enlarged.

Fig. 6 is a perspective view showing one example of the overall structure of the resin member of one embodiment of the present invention.

Fig. 7 is a plan view of a resin member of an embodiment of the present invention.

Fig. 8 is a view showing a process of roughening the mold surface.

Fig. 9A is a view showing an injection molding apparatus for producing a resin component of one embodiment of the present invention.

Fig. 9B is a diagram illustrating a process in which a cavity is formed in an injection molding apparatus.

Fig. 9C is a diagram illustrating a process in which resin is injected into a cavity of an injection molding apparatus.

Fig. 9D is a diagram showing a process in which the resin is cooled under a constant pressure after being injected into the cavity.

Fig. 9E is a diagram showing a process in which the mold is opened to take out the resin member.

Fig. 10 is a flowchart showing a procedure of evaluating an antireflection surface of a resin member of one embodiment of the present invention.

Fig. 11 is a photograph of a resin member according to an embodiment of the present invention observed by an electron microscope.

Fig. 12 is a histogram showing an example of the luminance distribution of the resin member of an embodiment of the present invention.

Fig. 13A is a plan view of an exemplary resin member of the present invention.

Fig. 13B is a plan view of a resin member of another example of the present invention.

Fig. 14 is a photograph of a resin member according to an example of the present invention observed with an electron microscope.

Fig. 15 is a diagram illustrating a method of measuring specular reflectance.

Fig. 16 is a graph showing the average reflectance of the antireflection surface of the resin member of one example of the present invention.

Fig. 17 is a table showing characteristics of samples of resin members of examples of the present invention.

Fig. 18 is a diagram showing a rough surface of a mold according to an embodiment of the present invention.

Fig. 19A is a diagram showing a state in which the mold surface of one embodiment of the present invention has not been irradiated with a pulsed laser.

Fig. 19B is a diagram showing a state in which the mold surface has been irradiated with several pulses of a pulsed laser.

Fig. 19C is a diagram showing a state in which the mold surface has been irradiated with several tens of pulses of a pulsed laser.

Fig. 19D is a diagram showing a state in which the mold surface has been irradiated with hundreds of pulses of the pulsed laser.

Fig. 20A is a view showing a state where a molten resin is injected into a mold and kept under low pressure.

Fig. 20B is a view showing a state where a molten resin is injected into a mold and held at an increased pressure.

Fig. 20C is a view showing a state where the molten resin is injected into the mold and is held at a further increased pressure.

Fig. 20D is a view showing a state where the molten resin is injected into the mold and is held under a further increased pressure.

Fig. 21A is a perspective view of a resin member having a large free surface.

Fig. 21B is a perspective view of a resin member having a medium-sized free surface.

Fig. 21C is a perspective view of a resin member having a small free surface.

Fig. 22A is a sectional view of a resin member having a large free surface.

Fig. 22B is a sectional view of a resin member having a medium-sized free surface.

Fig. 22C is a sectional view of a resin member having a small free surface.

Fig. 23 is a view showing a process of roughening the surface of the rolling die of one embodiment of the present invention.

Fig. 24 is a view showing a process of roll-molding a resin member using the mold prepared by the process of fig. 23.

Fig. 25A is a sectional view of a molding process for forming a resin member having a large free surface.

Fig. 25B is a sectional view of a molding process for forming a resin member having a medium-sized free surface.

Fig. 25C is a sectional view of a molding process for forming a resin member having a small free surface.

Fig. 26 is a graph showing the average reflectance of the antireflective surface of the resin member of another example of the present invention.

Fig. 27 is a view schematically showing an optical article including a resin member of the present invention.

Fig. 28 is a view schematically showing a filler added to the resin member of the present invention.

Fig. 29 is a diagram showing the effect of the filler added to the resin member of the present invention.

Fig. 30 is a table showing characteristics of samples of resin members of examples of the present invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Here, since the configuration described below is merely an example, a person skilled in the art may appropriately change the detailed configuration without departing from the spirit of the present invention. In addition, the numerical values described in the present embodiment are examples and are not intended to limit the present invention.

The resin article of the present embodiment is a resin member. Fig. 1A and 1B schematically show the antireflection surface of the resin member of the present embodiment. Fig. 1A is a perspective view schematically showing a resin member. Fig. 1B shows a cross section of the resin member taken along line a-a' of fig. 1A. In fig. 1A and 1B, the antireflection surface of the resin member includes a free surface 11 and a first concave portion 12.

Here, the term "free surface" is used herein for convenience to mean the free surface 11 formed on the antireflective surface of the resin article. Specifically, when a resin article is injection-molded by using a mold, some of the molten resin injected into the cavity does not contact the mold surface, and is solidified in a state where its free surface shape does not form the mold surface shape in the cavity. Thus, the free surface is the surface of the cured resin that retains its free surface shape. That is, the free surface herein is a portion of the outer surface of the resin member, and the portion has been cured, without the shape of the mold being transferred thereto.

When the resin member of the present embodiment is molded, the shape of the mold is transferred onto the resin material to form the antireflection surface. The shape of the mold may be transferred onto the resin material by using any method, such as injection molding or roll forming described in a second example described later. By using any one of these molding methods, and by setting molding conditions (for example, a pressure value applied to the resin material) required for transferring the mold shape, molding can be controlled so that the free surface is formed so that a part of the resin material does not contact the mold surface.

For example, in the case of forming the shape of the antireflection surface by injection molding, when the shape of the mold is to be transferred to a resin material, the resin material is injected into the mold under conditions that allow some of the resin material not to contact the mold surface to form a free surface. Injection molding is performed by appropriately selecting a resin material and adjusting the temperature and injection pressure of the resin material. Here, the free surface 11 may not be flat, and may be convex, concave, or wavy. If the free surface 11 is wavy, the wavy free surface may comprise concave-convex portions. The height of the portion of the free surface 11 may be different from the average height of the antireflection surface of the resin member and different from the height of the bottom surface of the first concave portion 12. Preferably, the free surface 11 includes convex portions each formed like a saddle to improve durability of the antireflection surface and promote light scattering performance on the antireflection surface to improve antireflection performance of the antireflection surface.

In fig. 1A, the first concave portions 12 are regularly arranged so as to form a honeycomb structure or a staggered arrangement. However, since fig. 1A is intended only to simplify the structure of the first concave portion 12 or to facilitate understanding of the first concave portion 12, the first concave portion 12 may be irregularly provided. For example, the first concave portions 12 may be randomly or irregularly arranged as shown in an electron microscope image described later. Preferably, the first concave portions 12 are randomly or irregularly arranged to increase light scattering performance on the anti-reflection surface, thereby improving anti-reflection performance.

Fig. 2 is an enlarged sectional view of a part of the first concave portion 12 of fig. 1B. On each of the first concave portions 12, a second concave portion 31 is formed. The second concave portion 31 forms the fine rough surface 23. In fig. 2, the outline of the cross section of each of the first concave portions 12 is indicated by a broken line. The broken line may be obtained by image processing (e.g., low-pass filtering) the cross-sectional image and plotting the average value of the fine rough surface 23. Each of the first concave portions 12 has a contour indicated by a dotted line, and has a concave shape having an opening width 21 and a depth 22. In the present embodiment, the ratio of the opening width 21 to the depth 22 is defined as the aspect ratio of the first concave portion 12.

In fig. 1B and 2, each of the first concave portions 12 has a tapered cross-sectional shape in which a diameter of a cross section of each of the first concave portions 12 decreases as each of the first concave portions 12 extends downward. However, the first concave portions 12 may have any cross-sectional shape, and the cross-sectional shapes of the first concave portions 12 may be different from each other and irregularly formed. For example, the first concave portion 12 may have a rectangular cross-sectional shape, or may have a teardrop-shaped cross-sectional shape. The teardrop-shaped cross-sectional shape is a shape that begins to widen toward the bottom at a predetermined depth. When the cross-sectional shapes of the first concave portions 12 are different from each other, the opening width 21 of each of the first concave portions 12 can be measured and evaluated by using a method described later with reference to fig. 4. The same is true for the depth 22 of the first recessed portion 12.

The surface of each of the first concave portions 12 of the resin member is not actually a smooth surface as shown by the broken line in fig. 2, but a fine rough surface 23 including a plurality of fine concave portions (second concave portions 31).

Fig. 3 is an enlarged perspective view of a part of the first concave portion 12. Fig. 3 shows the second concave portion 31. The second concave portions 31 each have an opening width of 1 μm or less, and are formed on the first concave portions 12 along the contour of the first concave portions 12. Here, although the second concave portions 31 are discretely formed in fig. 1A and 3, the second concave portions 31 may not necessarily be discretely formed. For example, the second concave portions 31 may be densely formed as shown in fig. 2, or adjacent second concave portions of the second concave portions 31 may partially overlap each other.

The fine rough surface 23 has only concave portions and convex portions formed on the contour of the surface of the first concave portion 12, as shown in fig. 2. In other cases, the concave portion may be formed only on the surface (indicated by outline) of the first concave portion 12, or only the convex portion may protrude from the surface (indicated by outline) of the first concave portion 12. When the protruding portion protrudes from the surface (indicated by the outline) of the first concave portion 12, the surface (indicated by the outline) of the first concave portion 12 will serve as a concave portion with respect to the protruding portion. As can be seen from fig. 2 and 3, the opening width of the second concave portion 31 is smaller than the opening width 21 of the first concave portion 12. The opening width of the second concave portion 31 is evaluated by using an observation image magnified by about 10,000 times by an electron microscope or the like.

Fig. 4 schematically shows a binarized enlarged image obtained by enlarging an image of the antireflective surface of the resin member and binarizing the enlarged image. A method of obtaining such a binarized image will be described later. In fig. 4, the unshaded portion 41 is a free surface corresponding to the free surface 11 of fig. 1. In addition, the hatched portion 42 corresponds to the first concave portion 12 shown in fig. 1A to 3. The free surface 41 is formed at a position higher than the concave portion 42. As described later, the free surface 41 is a surface of the resin material that does not contact the mold when the resin material is injected into the cavity in transfer (injection) molding using the mold.

The first concave portion 42 corresponding to the first concave portion 12 is concave with respect to the free surface 41. Preferably, the opening width 43 of the first concave portion 42(12) is equal to or more than 1 μm and equal to or less than 300 μm. In addition, the opening width of the second concave portion 31 (fig. 3) formed on the (hatched) first concave portion 42(12) is smaller than the opening width 43, and is preferably equal to or larger than 10nm and equal to or smaller than 1.5 μm. If the opening width of the second concave portion 31 is within this range, the antireflection surface can effectively suppress reflection of light having a wavelength smaller than that of near-infrared light.

Generally, the first concave portions 12 are formed to have random shapes and sizes, respectively. Therefore, a representative value of the opening width 43 of each of the first concave portions 42(12) can be measured and evaluated by using the following method. That is, a circle 43 '(shown in fig. 4) associated with the corresponding one of the first concave portions 42(12) and having the smallest area difference between the circle 43' and the corresponding concave portion is determined by image processing the electron microscope image, and the diameter of the circle is determined as a representative value of the opening width 43 of the corresponding one of the first concave portions 43 (12).

In the experiment conducted by the present inventors, if the opening width 43 of each of the first concave portions 42(12) is larger than 300 μm, the reflected light tends to become conspicuous in macroscopic observation and causes flickering of the light because each of the first concave portions 42(12) has a relatively large area from which the light is reflected. Therefore, the opening width 43 of the first concave portion 42(12) is preferably equal to or less than 300 μm.

Fig. 5 is a diagram in which a part of the binarized enlarged image of the antireflection surface of fig. 4 is further enlarged. In fig. 5, there is a distance 53 between adjacent two of the first concave portions 51(12), and the shortest distance among the distances 53 is denoted by reference numeral 52.

Therefore, one of the first concave portions 51(12) has only one shortest distance 52 between the one of the first concave portions 51(12) and the other concave portions surrounding the one of the first concave portions 51 (12). The shortest distance 52 can be measured and evaluated by the following process. For example, by processing an image (e.g., an electron microscope image), lines from the target concave portion to other concave portions surrounding the target concave portion are drawn so that each line becomes the shortest line. The minimum length of the line is then defined as the shortest distance 52 between the target recessed portion and the other recessed portions surrounding the target recessed portion.

In the present embodiment, the shortest distance 52 of the first concave portion 51(12) is preferably equal to or less than 100 μm. If the shortest distance 52 is greater than 100 μm, the antireflection performance may not be sufficiently exerted because the concave portions are too far from each other. More preferably, the shortest distance 52 of the first concave portion 51(12) is equal to or less than 15 μm.

As described above, the antireflection surface of the present embodiment includes the first concave portion 12 having the first opening width 43, and the second concave portion 31 (fig. 3), the second concave portion 31 being formed on the first concave portion 12 and having the second opening width smaller than the first opening width 43. In this configuration, since the second concave portion 31 is formed, the ratio of the area of the molded article to the area of the cross section of air is gently changed at a pitch smaller than the wavelength of near-infrared light. As a result, the refractive index of the antireflection surface is gently changed, thereby improving the antireflection performance.

In addition, since the first concave portion 12 having an opening width of at least 1 μm is formed on the anti-reflection surface, incident light having an oblique incident angle will be reflected from the first concave portion 12 a plurality of times and thus attenuated, which increases the anti-reflection performance of the anti-reflection surface. Here, since the light attenuates more as the number of reflections in the concave portion increases, it is more preferable that the depth from the free surface 41 to the bottom of the first concave portion 12 is made deeper.

In addition, when the aspect ratio (fig. 2) of the first concave portion 12 is large, light having a wide incident angle range ranging from an acute angle to an obtuse angle can be reflected multiple times. Therefore, as the aspect ratio increases, a stronger antireflection effect will be produced for oblique incident light. In order to increase the antireflection effect of obliquely incident light, the aspect ratio is preferably equal to or greater than 0.4. In addition, it is more preferable that the shape of the first concave portions 12 is formed such that the cross section of each of the first concave portions 12 becomes wider toward the bottom of each of the first concave portions 12, because the shape formed in this way increases the light shielding performance. As the aspect ratio of the first concave portion 12 increases, the light shielding performance will be further improved for the oblique incident light.

Each of the first concave portions 12 formed on the antireflection surface is surrounded by the other first concave portions 12 via a free surface 41, the free surface 41 being located higher than the inner surface of the first concave portion 12. This configuration can protect the second concave portion 31 (fig. 3) which is formed on the inner surface of the first concave portion 12 and forms a fine rough surface when, for example, contacting the antireflection surface.

In contrast, as in the conventional configuration described in japanese patent application laid-open No.2015-184428, although a fine rough surface is formed on the wavy antireflection surface, the free surface 41 is not formed at a position higher than the first concave portion 12. As a result, the fine rough surface will be easily damaged. Therefore, in the conventional configuration, when the anti-reflection surface is wiped for cleaning, the convex portion of the fine rough surface may be broken to generate dust, and the dust may enter the concave portion of the fine rough surface to deteriorate the anti-reflection performance of the anti-reflection surface.

However, in the present embodiment, since the second concave portion 31 forming the fine rough surface is formed on the inner surface of the first concave portion 12 surrounded by the higher free surface 41, the fine rough surface is hardly damaged even at the time of wiping, and thus the deterioration of the antireflection performance of the antireflection surface can be prevented.

Fig. 6 is a perspective view of a resin member 61 having the antireflection surface 62 of the above-described embodiment. The resin member 61 of fig. 6, specifically, the antireflection surface 62 can be formed by transferring the shape of the mold surface to the resin material. The molding in which the surface shape of the mold is transferred can be performed by using any transfer method, such as injection molding, roll forming, or press forming.

The resin member 61 may be formed in any shape, such as a thin flat shape or a curved shape of a sheet or a film or the like. In fig. 6, for ease of understanding, the resin member 61 is a rectangular flat member as an example. However, the resin part 61 may be formed in any shape to serve as a support member or a case member depending on the shape of the mold. Here, the support member or the case member may be a lens holder or a lens barrel that accommodates the optical element, and it requires light shielding performance and antireflection characteristics for the optical apparatus, as described below.

The resin material of the resin member 61 may be a thermoplastic material such as polyethylene, polystyrene, polypropylene, polyvinyl chloride, polyester, polyamide, or polycarbonate. In addition, the resin material of the resin member 61 may be transparent or colored, and may be a high-strength resin material containing a glass filler or carbon fibers.

When the filler is added to the resin material for injection molding, the antireflection effect can be further increased. Fig. 28 shows an enlarged cross section of the antireflection surface 62 of the resin member 61 to which a filler is added. In fig. 28, a resin 2800 and filler particles 2801 are shown. When the filler particles 2801 are added, the filler particles 2801 move close to the outer surface of the resin member, that is, to a position close to the free surface. Therefore, the filler particles 2801 undulate the free surface at a high frequency, thereby improving the scattering effect of light.

The filler content in the resin material of the resin member is preferably equal to or more than 5 mass% and equal to or less than 45 mass%. If the content of the filler is less than 5 mass%, the free surface fluctuation is small, and thus an insufficient scattering effect may be generated. On the other hand, if the content of the filler is more than 45 mass%, moldability may be lowered. For example, when moldability in injection molding is lowered, fluidity of the resin is lowered, thereby possibly causing deterioration in appearance such as shortening or sink marks.

The shape of the filler particles may be long and cylindrical. In this case, it is preferable that the particle diameter of the filler is equal to or more than 20 μm and equal to or less than 80 μm, and the particle length of the filler is equal to or more than 70 μm and equal to or less than 100 μm. If the particle diameter of the filler is less than 20 μm or the particle length of the filler is less than 70 μm, the filler may protrude from the free surface when pressurized to move the filler toward the free surface, thereby possibly deteriorating the appearance. On the other hand, if the particle diameter of the filler is larger than 80 μm or the particle length of the filler is larger than 100 μm, the free surface may not be sufficiently fluctuated because the filler is not pressurized to be movably close to the free surface.

Preferably, the free surface undulates such that the arithmetic mean curvature Spc is equal to or greater than 1500[1/mm ] and equal to or less than 9000[1/mm ], the arithmetic mean curvature being a two-dimensional evaluation of the peaks of the wave-shaped portion of the free surface. When the arithmetic mean curvature Spc of the peak of the waveform portion is within the above range, the resin member 61 can have better antireflection performance.

Here, the arithmetic mean curvature Spc of the peak of the wave-shaped portion of the free surface will be described. The arithmetic mean curvature Spc of the peak is the mean of the main curvatures of the peaks of the wave-shaped portion of the free surface. Fig. 29 is a sectional view of a concave-convex portion of the free surface for describing an arithmetic mean curvature Spc of a peak of a waveform portion 2900 of the free surface. The measurement area shown in fig. 29 has a size of about 1000 × 1000 μm. The following equation represents an equation for calculating the arithmetic mean curvature Spc of the peak. In this equation, a parameter z represents a height component obtained at a position coordinate (x, y), and a parameter n represents the number of peaks. Therefore, the arithmetic mean curvature Spc of the peak is the mean of the reciprocal of the radius of the approximate circle 2901 of the peak of the waveform portion of fig. 29. Therefore, when the arithmetic mean curvature Spc is small, the peak is rounded and wide; when the arithmetic mean curvature Spc is large, the peak is sharp and narrow.

Here, when the arithmetic mean curvature Spc of the peak is larger than 9000[1/mm ], the convex portion of the wavy portion of the free surface is sharp and narrow. The convex portion allows incident light on the molded article to be easily reflected and scattered, thereby making it possible to improve the anti-reflection performance. However, as the convex portion of the wavy portion of the free surface becomes sharper, the durability against wiping tends to be more deteriorated.

On the other hand, when the arithmetic mean curvature Spc of the peak is less than 1500[1/mm ], more light is reflected from the wavy portion of the free surface, so that the effect of the filler contained in the resin material may be impaired. Therefore, the convex portion of the wavy portion of the free surface is preferably formed such that the arithmetic mean curvature Spc is equal to or greater than 1500[1/mm ] and equal to or less than 9000[1/mm ].

The mold for molding the resin member 61 can be produced by roughening the mold surface by irradiating the mold surface with a short pulse laser having a pulse width of 10 ^-12Seconds or less. When the pulse width of the laser light for processing is 10 ^-12The laser causes self-organization of the mold surface in seconds or less, and thus the surface of the mold can be effectively roughened. By such laser processing, fine protrusions can be formed on the surface of the mold. Then, the shape of the fine protrusions of the mold is transferred onto the resin material to form a fine rough surface 23 having second concave portions 31 formed on the inner surfaces of the first concave portions 12, as shown in fig. 3.

Fig. 7 shows a binarized image of the antireflection surface 62 of the resin member 61 of fig. 6 photographed by an electron microscope. In fig. 7, the first concave portion 71(12) and the free surface 72 are shown. The free surface 72 surrounds each of the first concave portions 71 (12). When the ratio of the area of the first concave portion 71(12) to the area of the entire antireflection surface 62 is small, that is, when the free surface is large, the reflectance is increased while the durability is improved. On the other hand, when the ratio of the area of the first concave portion 71(12) to the area of the entire antireflection surface 62 is large, the reflectance is reduced while the durability is reduced. The ratio of the area of the first concave portion 71(12) to the area of the entire antireflection surface 62 is preferably equal to or more than 10% and equal to or less than 95%, because when the ratio is less than 10%, the antireflection performance is significantly reduced. More preferably, the ratio of the area of the first concave portion 71(12) to the area of the entire antireflection surface 62 is equal to or more than 50% and equal to or less than 80% because the durability and the antireflection performance are well balanced in this range. Hereinafter, specific examples of the configuration, use, and manufacturing method of the resin member used in the present embodiment will be described.

First example

In a first example, a manufacturing process of a mold for molding a resin part and a method for evaluating the molded resin part will be described. First, as shown in fig. 8, by irradiating the mold surface 82 with the above-described short pulse laser, the mold surface 82 whose shape is to be transferred to the antireflection surface of the resin member is roughened. The mold 81 shown in fig. 8 may be made of any material, such as stainless steel, copper, or aluminum, which is suitable for the molding process performed after the roughening process.

Short-pulse laser light different from the laser light performing continuous irradiation is repeated for a short time. A short pulse laser that irradiates for a period of several picoseconds to several hundred picoseconds is called a picosecond laser. A short pulse laser that irradiates for a period of several femtoseconds (shorter than one picosecond) to several hundred femtoseconds is called a femtosecond laser. In the first example, a picosecond laser or a femtosecond laser may be suitably used. In laser processing described later, it is preferable to use a pulse width of 10 ^-12The surface of the mold is irradiated with a pulsed laser for a second or less (subpicosecond) to roughen the surface of the mold. In the first example, the laser processing apparatus used is an apparatus whose settings such as laser irradiation intensity, pulse length, and pulse interval can be freely selected.

The laser processing apparatus may be an ultra-short pulse laser oscillator manufactured by AMPLITUDE SYSTEMS. The ultra-short pulse laser oscillator generates laser light 83 for processing. The wavelength of the laser 83 is 1030nm, and the pulse width of the laser 83 is 500 femtoseconds (fs). The pulse energy produced by each pulse of laser 83 is 40 muj and the focal length of lens 84 is about 170 mm. By adjusting the distance between the lens 84 and the mold surface, the spot diameter of the irradiation region 85 can be adjusted to 40 μm.

With these parameters, the area of the irradiated region 85 is about (1.3 × 10) ^-3mm) ²And the energy density of one pulse of laser light at the irradiation region 85 is about 30kJ/m ². The area of the mold surface 82 to be roughened is scanned by the laser by moving the mold using a scanning stage (not shown).

Arrow 86 of fig. 8 represents the trace along which laser 83 scans mold surface 82 for machining. Wherein the speed at which the laser 83 scans the mold surface 82 is 30mm/s, the scanning interval is 20 μm, and the irradiation frequency of the short pulse laser is 500 kHz. One irradiation area was irradiated with about 1,000 pulses of a pulsed laser.

The number of pulses N of the pulsed laser light irradiating one irradiation region can be determined by the following equation. In this equation, the parameter V [ mm/s ]]Is the speed of the laser scanning the mold surface 82, parameter L mm]Is the scan interval, parameter S [ mm ] ²]Is the surface of the irradiation region 85Product, and parameter f [ times/s ]]The irradiation frequency of the short pulse laser is set.

N＝f·S/(V·L)

Here, the scanning interval L is smaller than the spot diameter of the irradiation region 85, and is generally close to half the spot diameter. In addition to the number of irradiation pulses, other irradiation conditions of the laser light may be controlled, which include the pulse width of the laser light and the energy density at the irradiation region. Therefore, by appropriately selecting these irradiation conditions, it is possible to form a special rough surface on the surface of the mold which is difficult to achieve by the cutting process.

When the mold surface 82 of the mold 81 on which laser processing was performed using the above conditions was observed by an electron microscope, a fine rough surface having a concave-convex structure was obtained as shown in an electron microscope image. Fig. 18 is a perspective view schematically showing the concave-convex structure of the mold surface 82. With the above-described conditions regarding laser processing, the pitch P between adjacent two projecting portions 1007 (fig. 18) of the concavo-convex structure is equal to or greater than 20 μm and equal to or less than 40 μm, and the height H of the projecting portion 1007 of the concavo-convex structure is equal to or greater than 50 μm and equal to or less than 80 μm. Here, the top portion of the convex portion 1007 according to the concave-convex structure of the mold surface 82 forms the shape of the bottom portion of the first concave portion 12 of the resin member. In the concave-convex structure constituted by the plurality of convex portions 1007, the convex portions 1007 are formed at a pitch larger than the wavelength of visible light. The pitch P may vary in the range of 10 to 100 μm and the height H may vary in the range of 10 to 100 μm according to the irradiation condition of the short pulse laser. In addition, a steep concave-convex structure in which the pitch P is almost equal to the height H may be used according to the intended use.

In the fine rough surface shown in fig. 18, fine concave-convex portions are formed on the concave-convex structure of the mold surface 82 (particularly on the convex portion 1007), so as to cover the surface of the convex portion 1007. The pitch of the fine concave-convex portions is equal to or more than 40nm and equal to or less than 80nm, and the height of the fine concave-convex portions is equal to or more than 40nm and equal to or less than 80 nm. The second concave portion 31 on the inner surface of the first concave portion 12 of the resin member is formed in accordance with the minute concave-convex portion covering the surface of the convex portion 1007 of the mold surface 82. Therefore, according to the conditions of laser processing, a concave-convex structure including a plurality of convex portions 1007 and fine concave-convex portions covering the surface of the convex portions 1007 is formed on the mold surface 82. That is, the mold surface 82 is given a special shape in which a large concave-convex structure and a small concave-convex portion are combined. The large concave-convex structure is used to form the first concave portion 12 of the resin member, and the small concave-convex structure is used to form the second concave portion 31 of the resin member.

In this way, it is possible to form the first projecting portion having a diameter of 1 μm or more and the second projecting portion having a diameter of 10nm or more and 1 μm or less on the molding surface of the mold.

Although the mechanism of development of the particular shape of the mold surface 82 in which the concavo-convex structure and the fine protrusions are combined as shown in fig. 18 is not completely known, the general process of development will be described below.

Fig. 19A shows a cross section of the mold 1901 that has not yet been irradiated with the pulsed laser. At this stage, since the mold surface has been processed into a flat surface or a mirror surface by the preparatory treatment, there is no significant uneven portion on the mold surface.

Fig. 19B shows a cross-section of a mold 1902 that has been irradiated with several pulses of a pulsed laser. At this stage, since some of the metal of the mold has evaporated from the mold surface and some of the metal has accumulated on the mold surface, the concave-convex portion 1905 is formed. At this stage, the depth of the concave-convex portion is several tens of nanometers.

Fig. 19C shows a cross section of a mold 1903 that has been irradiated with several tens of pulses of a pulsed laser. In this process, more metal evaporates from the more concave portions of the mold surface. As a result, the concave-convex structure shown in fig. 19C is formed. In this process, some of the metal collects on the surface of the relief structure and forms small lumps, and the lumps become protrusions. At this stage, the depth of the concave-convex portion is several micrometers.

Fig. 19D shows a cross-section of a mold 1904 that has been irradiated with hundreds of pulses of a pulsed laser. Also, in this process, more metal evaporates from the more concave portions of the mold surface. As a result, the lower projecting portions disappear, and only the higher projecting portions remain. As this phenomenon continues, the number of convex portions and concave portions decreases, and the height between the convex portions and concave portions increases, as shown in fig. 19D. The surface of the relief structure is covered with small agglomerated masses.

In the above manner, a special shape in which the concavo-convex structure and the small concavo-convex portion are combined as shown in fig. 18 is formed on the mold surface. At this stage, the grown relief structure has a pitch of about several tens of micrometers and a height of about several tens of micrometers. As described above, by roughening the mold surface using a short pulse laser, the mold can be processed in a short time and at low cost. If the same shape is formed by cutting a die or using photolithography, it will take several times longer than the time taken by the method using a short pulse laser.

As described above, a mold surface formed by a short pulse laser and having a special shape generates only a small amount of reflected light with respect to incident light having various incident angles. In addition, as a result of the studies by the present inventors, a resin member obtained by transferring the shape of the mold surface to a resin material can also be used as a light-shielding member, which suppresses reflection of light. Therefore, if a special shape is formed on the surface of a mold by using a short pulse laser, and then a resin part (molded article) is manufactured by using the mold, a light shielding member that suppresses light reflection and has high performance can be manufactured in a short time and at low cost.

Fig. 9A to 9E illustrate a process of injection molding a resin part by using the mold 91 manufactured in the above-described manner. Here, a resin part was made by using an injection molding machine J180EL III (product name) manufactured by THE he JAPAN stem WORKS, ltd. The injection molding machine shown in fig. 9A to 9E includes a pressure device 911 communicating with the cylinder 99 and a hopper 910 supplying a resin material.

The cylinder 99 includes a screw (not shown) that is rotated by a driving source (not shown) such as a motor. As the screw rotates, the resin material in the hopper 910 is sent to the front end portion of the cylinder 99. In addition, the cylinder 99 is provided with a heater (not shown). Therefore, when the resin material is supplied from the hopper 910, the resin material is heated in the cylinder 99 until reaching a temperature equal to or greater than the glass transition temperature on the way to the front end portion of the cylinder 99, and is melted into a liquid. The molten resin material is stored in a space at the front end portion of the cylinder 99.

The mold 91 shown in fig. 9A to 9E corresponds to the mold shown in fig. 18 and has a rough mold surface. In fig. 9A to 9E, the opposing mold 98 is used to close the mold 91.

The resin material supplied from the hopper 910 may be polycarbonate G3430H with glass filler, which is manufactured by TEIJIN LIMITED. In addition, the resin material may be colored black by using a colorant.

First, as a mold preparation process, a mold is attached to an injection molding machine, as shown in fig. 9A. Then, as shown in fig. 9B, the mold 91 is closed by a driving mechanism (not shown) using the opposing mold 98. The mold 91 and the opposing mold 98 are heated by a heater (not shown) before or while the mold 91 is closed. The temperature at which the mold 91 and the opposing mold 98 are heated in this process is referred to as the mold temperature.

After this process, the injection process of fig. 9C and the pressure holding process and the cooling process of fig. 9D are performed. In the injection process of fig. 9C, molten resin 912 is injected from a cylinder 99 into a cavity formed by the mold 91 and the opposing mold 98 by a pressure device 911. The pressure device 911 may comprise a hydraulic cylinder. In the pressure holding process and the cooling (solidifying) process of fig. 9D, the molten resin 912 of the cavity is pressurized by the pressure device 911 at a predetermined pressure allowing the free surface 41 to be formed, and the pressure is held for a predetermined time (pressure holding process). Therefore, the pressure applied to the molten resin 912 in the cavity formed by the mold 91 and the opposing mold 98 is maintained at a constant pressure described later.

Here, the control of the transfer pressure or the constant pressure of the present example will be described. In the usual injection molding, the transfer pressure or constant pressure is set so that the cavity formed by the mold 91 and the opposing mold 98 is filled with the molten resin 912. In contrast, in the present example, the constant pressure is set so that the cavity is not filled with the molten resin 912. The constant pressure is set in this way to form the free surface 41 for surrounding the first concave portion 12, and the ratio (area ratio) of the area of the first concave portion 12 or the free surface 41 to the area of the entire antireflection surface is controlled. Hereinafter, control of the holding pressure in the injection molding of the present example will be described with reference to fig. 20A to 20D.

Fig. 20A to 20D schematically show changes in the shape of the interface between the mold 91 and the molten resin 912 caused when the constant pressure is changed in the process of fig. 9D. In fig. 20A to 20D, a cross section 2014 of the surface of the mold 91 of fig. 9 has a shape in which the concave-convex structure and the small concave-convex portion are combined by the laser processing of the above mold. The molten resin 2012 corresponds to the molten resin 912 of fig. 9.

Fig. 20A shows a state under a certain constant pressure. In fig. 20A, molten resin 2012 contacts the top portion of the convex portion of mold 2014, but does not contact the concave portion of mold 2014. As a result, a space 2015 is formed between the molten resin 2012 and the mold 2014, particularly between the molten resin 2012 and the concave portion of the mold 2014. Fig. 20B shows a state in which the constant pressure is higher than that of fig. 20A. As shown in fig. 20B, the molten resin 2012 contacts the convex portion of the mold 2014, but does not contact the concave portion of the mold 2014. As a result, a space 2015 is formed. However, the space 2015 is smaller than that of fig. 20A.

Fig. 20C shows a state in which the constant pressure is higher than that of fig. 20B. As shown in fig. 20C, the molten resin 2012 contacts the convex portion of the mold 2014, but does not contact the concave portion of the mold 2014. As a result, a space 2015 is formed. However, the space 2015 is smaller than that of fig. 20A and 20B. Therefore, in the pressure holding process of the present example, the constant pressure is set so that a space 2015 not filled with the molten resin 2012 is formed as shown in fig. 20A to 20C. When the molten resin 2012 does not contact the concave portion of the mold 2014 and forms the space 2015 as shown in fig. 20A to 20C, the surface of the molten resin 2012 facing the space 2015 is not affected by the shape of the mold surface and becomes a free surface. When the molten resin 2012 is cooled and solidified in this state, a free surface 41 surrounding the first concave portion 12 is formed, which has an irregular height and is shaped like a saddle. That is, in the present example, the constant pressure is set so that a space 2015 is formed between the molten resin 2012 and the mold 2014, particularly between the molten resin 2012 and the concave portion of the mold 2014, and that the surface of the molten resin 2012 facing the space 2015 becomes a free surface.

Here, when the constant pressure is further increased, the state shown in fig. 20D is produced. In fig. 20D, since the molten resin 2012 contacts not only the convex portion of the mold 2014 but also the concave portion of the mold 2014, a space 2015 as shown in fig. 20A to 20C is not formed. In the conventional injection molding, the constant pressure is set so that the state of fig. 20D is produced. However, this state is not generated in this example.

Referring again to fig. 9D, after the molten resin 912 is pressurized at a constant pressure for a predetermined time, the mold 91 and the opposing mold 98 are cooled, thereby cooling the molten resin 912 to a temperature equal to or less than the glass transition temperature, thereby changing the state of the molten resin 912 from a liquid state to a solid state. Here, the mold 91 and the opposing mold 98 may be cooled by a mechanism (not shown) that circulates a coolant around the mold 91 and the opposing mold 98. Then, as shown in fig. 9E, the mold 91 is opened and separated from the opposing mold 98. The separation may be performed by protruding an ejector pin passing through the mold 91 into the cavity. Accordingly, many resin parts 913 can be manufactured by repeating the above-described process.

In the first example, in the injection process of fig. 9C, the mold temperature was set to 125 ℃, and the resin temperature was set to 320 ℃. In the pressure holding process of fig. 9D, the pressure device 911 is used, and thereby a pressure that allows the concave portion of the mold surface 82 to be not filled with the molten resin 2012 is applied to the molten resin 2012 of the cavity. In the pressure holding process of fig. 9D, the pressure value is set so that the free surface 41 is formed. Specifically, the pressure value is set so that a free surface is formed without the molten resin 2012 contacting the concave portion of the mold surface 82. As an example, injection molding is performed under two pressure conditions of 60MPa and 90 MPa. Through the above-described process, the resin part 913 that includes the corresponding antireflection surface and can function as the light shielding member is obtained.

Fig. 21A to 21C and fig. 22A to 22C schematically show an antireflection surface of a resin member suitably manufactured in the present example. FIG. 22A is a cross-sectional view of the antireflective surface of FIG. 21A taken along line A-A' of FIG. 21A. FIG. 22B is a cross-sectional view of the antireflective surface of FIG. 21B taken along line B-B' of FIG. 21B. FIG. 22C is a cross-sectional view of the antireflective surface of FIG. 21C taken along line C-C' of FIG. 21C.

The antireflection surface of the resin member shown in fig. 21A to 21C and fig. 22A to 22C is characterized by combining the free surface 11 smoother than the first concave portion 12 and the first concave portion 12 surrounded by the free surface 11. As described above, the small second concave portion 31 is formed on the inner surface of the first concave portion 12, and therefore the inner surface of the first concave portion 12 is rougher than the free surface 11. Here, in fig. 21A to 21C, the first concave portions 12 are regularly provided for easy understanding. However, as shown in fig. 11, in an actual antireflection surface, the shape, position, and size of the first concave portion 12 are formed randomly.

As described previously, the free surface 11 is formed so that the surface of the resin material around the first concave portion 12 does not contact the mold for molding the resin member, and so that the surface of the resin material takes a free shape. On the other hand, the second concave portion 31 formed on the inner surface of the first concave portion 12 is in contact with the mold surface during the pressure holding process. Therefore, since the fine rough surface of the mold surface has been transferred to the resin material, the first concave portion 12 has a rough surface.

The resin member shown in fig. 21A and 22A is formed by using a low constant pressure, and therefore the total area of the free surface 11 is large, and the total area of the first concave portion 12 having the second concave portion 31 is small. When injection molding is performed under a condition of a constant pressure such that the molten resin of the mold is in a state as shown in fig. 20A, a shape as shown in fig. 21A and 22A can be obtained.

When injection molding is performed under a condition of constant pressure such that the molten resin of the mold is in a state as shown in fig. 20B, the shape as shown in fig. 21B and 22B can be obtained. In the resin member shown in fig. 21B and 22B, the ratio of the area of the free surface 11 to the area of the entire antireflection surface is almost equal to the ratio of the area of the first concave portion 12 having the second concave portion 31 to the area of the entire antireflection surface.

In the resin member shown in fig. 21C and 22C, the total area of the free surface 11 is small, and the total area of the first concave portion 12 having the second concave portion 31 is large. When injection molding is performed under a condition of a constant pressure such that the molten resin of the mold is in a state as shown in fig. 20C, a shape as shown in fig. 21C and 22C can be obtained.

As shown in the evaluation results described later (for example, fig. 17), it has been found that when the antireflection surface has a structure as shown in fig. 21A and 22A, fig. 21B and 22B, or fig. 21C and 22C, the antireflection surface has good antireflection performance and durability. That is, the structure having good antireflection performance and durability is formed such that the first concave portion 12 having the second concave portion 31 is surrounded by the free surface 11. The formation of the structure with the free surface 11 can be controlled according to the conditions of the (constant) pressure used when transferring the shape of the mould surface.

On the other hand, if the resin member is molded under a condition of a constant pressure that allows all the shapes of the mold surface to be transferred to the molten resin in the state of fig. 20D, it is difficult to form the free surface 11 on the resin member (for example, the resin member corresponds to sample 5 described later). In this case, as described later, although the resin member has good antireflection performance, the durability of the antireflection surface of the resin member is lowered because it is difficult to form the free surface 11 which is located higher than the first concave portion 12 and protects the first concave portion 12. In addition, releasability of the resin part from the mold is reduced in the mold separation process (fig. 9E), and thus a part of the resin part may be broken. Such problems may reduce the yield and impair stable injection molding. As described above, the transfer state as shown in fig. 20D is not preferable. That is, since the surface roughened by the short pulse laser has a steep concave-convex structure, if the resin material enters and reaches the bottom of the steep concave-convex structure in the transfer state as shown in fig. 20D, a large force will be required to separate the resin member from the mold. As a result, cracks may be generated in the resin material at positions where the stress exceeds the yield point.

In contrast, in the state shown in fig. 20A to 20C as in the present example, since the resin material does not reach the bottom of the steep uneven structure, the resin member can be separated from the mold with a small force. Therefore, in the present example, in addition to the fact that the free surface 11 can be formed so as to protect the first concave portion 12 as described above, when the resin member is separated from the mold, the stress hardly exceeds the yield point, and the resin member hardly causes cracking.

The light shielding performance or the antireflection performance of the molded resin part can be evaluated by the measurement of the specular reflectance described later. In this evaluation, it has been found that as the flatness of the free surface 11 is lowered, the reflected light tends to be reduced, thereby improving the light shielding performance.

Here, a method of calculating and evaluating the ratio (area ratio) of the area of the first concave portion manufactured in the above-described manner to the area of the entire antireflection surface of the resin member will be described. Fig. 10 is a flowchart showing a process of calculating a ratio of the area of the first concave portion to the area of the entire antireflection surface. Here, the area of the first concave portion and the area of the entire antireflection surface are areas in a plan view. In a first example, the data is analyzed by using electron microscope images. By using an electron microscope, the distribution of the free surfaces 41(11) and the distribution of the first concave portions 42(12) and the ratio of the area of the free surfaces 41(11) to the area of the first concave portions 42(12) of the resin member of fig. 4 can be determined by the difference in luminance values.

In step S1 of fig. 10, a secondary electron image observed by using an electron microscope is stored. In step S2, the image stored in step S1 is quantized with 256-gray (8-bit) luminance values to form a histogram. Since the free surface has a high luminance value and the first concave portion has a low luminance value, the distribution in the histogram is divided into two opposite portions. Then, a luminance value that is located between the two opposing portions and gives a minimum point is determined as a threshold value for dividing the distribution into a distribution on the free surface and a distribution on the first concave portion.

In step S3 of fig. 10, the image is binarized so that pixels whose luminance value is equal to or greater than the threshold value are determined to be white, and pixels whose luminance value is less than the threshold value are determined to be black. Then, the ratio of the number of binarized white pixels to the number of binarized black pixels is determined as the ratio of the area of the free surface to the area of the first recessed portion. Although the binarization is performed by using the observation image taken by the electron microscope in the present example, the binarization may be performed by using another method. For example, a histogram may be formed by using height data obtained by laser microscope measurement.

Fig. 11 shows a secondary electron image taken by the electron microscope in step S1 of fig. 10. In fig. 11, the portion having a high luminance value corresponds to the free surface 41, and the portion having a low luminance value corresponds to the first concave portion 12. In particular, the portion of the surface that is roughened has a low luminance value (that is, the portion is dark) as the inner portion of the first concave portion 12.

Fig. 12 is a histogram in which the luminance values of the image obtained in step S2 of fig. 10 are shown in 256 levels of gray. In fig. 12, the horizontal axis represents 256-level gray scale and the vertical axis represents the number of pixels. Reference numeral 121 denotes a peak in the gray scale, which corresponds to the first concave portion 12. Reference numeral 122 denotes another peak in the gradation, which corresponds to the free surface 41. In addition, reference numeral 123 denotes a minimum point located between a peak corresponding to the free surface 41 and a peak corresponding to the first concave portion 12. The gray point corresponding to the minimum point may be set as the threshold value for binarization.

Fig. 13A and 13B show results obtained by binarizing the histogram. Fig. 13A shows the result obtained by binarizing the histogram of the resin member molded by using a constant pressure of 60MPa in the pressure holding process of fig. 9D. Fig. 13B shows the result obtained by binarizing the histogram of the resin member molded by using a constant pressure of 90MPa in the pressure holding process of fig. 9D. In fig. 13A, the ratio of the area of the first concave portion to the area of the entire antireflection surface is 34%; in fig. 13B, the ratio of the area of the first concave portion to the area of the entire antireflection surface is 64%.

In fig. 13A and 13B, the first concave portion 131 corresponds to the first concave portion 12, and the free surface 132 corresponds to the free surface 11. In addition, reference numeral 133 denotes an opening width of the first concave portion 131, and reference numeral 134 denotes the shortest distance among distances each measured between two adjacent first concave portions of the first concave portion 131. The opening width 133 of the first concave portion 131 of fig. 13A is equal to or more than 20 μm and equal to or less than 30 μm. The opening width 133 of the first concave portion 131 of fig. 13B is equal to or more than 20 μm and equal to or less than 30 μm. The aspect ratio of the first concave portion of fig. 13A is in the range of 0.45 to 1.51, and the aspect ratio of the first concave portion of fig. 13B is in the range of 0.55 to 1.67. The shortest distance among distances each measured between two adjacent first concave portions of the first concave portions 131 of fig. 13A is 10 μm, and the shortest distance among distances each measured between two adjacent first concave portions of the first concave portions 131 of fig. 13B is 8 μm. Therefore, when a higher constant pressure of 90MPa is applied to the molten resin, the area of the first concave portion 131 increases, and the area of the free surface 132 decreases. This is because when a large pressure is applied to the molten resin 912, the molten resin 912 enters the bottom portion of the concave portion of the mold surface 82.

Fig. 14 is an image of the second concave portion 31 formed on the inner surface of the first concave portion 131 observed by an electron microscope. In fig. 14, reference numeral 141 denotes the maximum width of the second concave portion 31, and reference numeral 142 denotes the minimum width of the second concave portion 31. In the present example, the maximum width 141 of the second concave portion 31 is 200nm, and the minimum width 142 of the second concave portion 31 is 50 nm.

In addition, in order to evaluate the properties of the resin parts molded under two constant pressures of 60MPa and 90MPa, the specular reflectance of the resin parts was measured by using a reflectometer manufactured by JASCO Corporation. As shown in fig. 15, the specular reflectance is obtained by measuring the intensity of incident light 151 having a certain incident angle, then measuring the intensity of reflected light 152 reflected from the surface of the sample 153 and having a reflection angle equal to the incident angle, and then determining the ratio of the intensity of the reflected light to the intensity of the incident light.

The specular reflectance has a large value if the surface of the sample 153 resembles a specular surface. In contrast, if the surface of the sample 153 is roughened, the specular reflectance has a smaller value. Therefore, when the resin part of the present invention is used as a light shielding member for a part such as a mirror holder described later, the light shielding member requires light shielding performance or antireflection performance, and the performance of the resin part is better if the specular reflectance of the resin part has a lower value.

The specular reflectance of the resin member molded under two constant pressures of 60MPa and 90MPa was measured with an incident angle of 5 ° to 85 °. In addition, since the reflectance depends on the wavelength of incident light, the measured values of light having a wavelength of 500nm to 600nm are averaged, and the average value is determined as the average reflectance. Fig. 16 shows the measurement results regarding specular reflectance.

In fig. 16, a curve 161 represents a measured value of the specular reflectance of the antireflective surface of the resin member injection-molded under a constant pressure of 60 MPa. The antireflection surface has a larger ratio of the area of the free surface 41 to the area of the entire antireflection surface, and a smaller ratio of the area of the first concave portion 12 to the area of the entire antireflection surface. In general, as the incident angle increases, the average reflectance tends to increase. In the conventional light shielding member, the average reflectance at an incident angle of 85 ° is close to 10%. However, curve 161 of fig. 16 shows that the reflectance is less than 5% at an incident angle of 85 °. Therefore, it was found that the resin member had good antireflection performance.

In fig. 16, a curve 162 represents a measured value of the specular reflectance of the antireflective surface of the resin member injection-molded under a constant pressure of 90 MPa. The antireflection surface has a smaller ratio of the area of the free surface 41 to the area of the entire antireflection surface, and a larger ratio of the area of the first concave portion 12 to the area of the entire antireflection surface. The measurement of specular reflectance represented by curve 162 is better than the measurement represented by curve 161. That is, the average reflectance of the resin part injection-molded under the constant pressure of 90MPa is lower than the average reflectance of the resin part injection-molded under the constant pressure of 60MPa at all the incident angles of 5 ° to 85 °. Therefore, it was found that the resin part injection-molded at a constant pressure of 90MPa had better anti-reflection performance than that of the resin part injection-molded at a constant pressure of 60 MPa.

Fig. 26 shows the measurement results of the specular reflectance of the resin member injection-molded at a lower constant pressure of 40MPa in the same manner as that of fig. 16, except for the measurement results of the specular reflectance of the resin member injection-molded at constant pressures of 60MPa and 90 MPa.

In fig. 26, a curve 3029 is equal to the curve 161 of fig. 16, and represents a measured value of the specular reflectance of the antireflective surface of the resin part injection-molded under a constant pressure of 60 MPa. In addition, a curve 3030 of fig. 26 is equal to the curve 162 of fig. 16, and represents a measured value of the specular reflectance of the antireflective surface of the resin member injection-molded under a constant pressure of 90 MPa.

In fig. 26, a curve 3028 represents the measured value of the specular reflectance of the antireflective surface of the resin member injection-molded under a constant pressure of 40 MPa. The antireflection surface has a larger ratio of the area of the free surface 41 to the area of the entire antireflection surface, and a smaller ratio of the area of the first concave portion 12 to the area of the entire antireflection surface. It can be seen that even when a constant pressure of 40MPa, lower than 60MPa, is applied to the resin material, curve 3028 shows a mirror reflectivity of less than 5% at an incident angle of 85 °. Therefore, it was found that the resin member injection-molded under a constant pressure of 40MPa still had good anti-reflection properties.

Fig. 17 is a table showing the antireflective properties and durability of sample 1, sample 2, sample 3, sample 4, sample 5, and sample 6. The samples are various resin parts molded under various conditions including conditions related to a constant pressure in injection molding and conditions related to injection molding such as a molten resin temperature.

Sample 1 of fig. 17 was molded, in which the conditions of injection molding were adjusted so that the ratio of the area of the first concave portions to the area of the entire antireflection surface was 34%, and the shortest distance of the first concave portions was 10 μm. Sample 2 was molded in which the conditions of injection molding were adjusted so that the ratio of the area of the first concave portions to the area of the entire antireflection surface was 64%, and the shortest distance of the first concave portions was 8 μm. Sample 3 was molded in which the conditions of injection molding were adjusted so that the ratio of the area of the first concave portions to the area of the entire antireflection surface was 10%, and the shortest distance of the first concave portions was 100 μm. Sample 4 was molded in which the conditions of injection molding were adjusted so that the ratio of the area of the first concave portions to the area of the entire antireflection surface was 95%, and the shortest distance of the first concave portions was 5 μm.

In samples 1 to 4, the free surfaces 41 are distributed so that the first concave portion 12 is surrounded by the free surfaces 41 of the antireflection surface. Here, the ratio of the area of the free surface 41 to the area of the entire antireflection surface may be a value obtained by subtracting the ratio of the area of the first concave portion to the area of the entire antireflection surface from 100%.

Sample 5 was molded in which the conditions of injection molding were adjusted so that the ratio of the area of the first concave portions to the area of the entire antireflection surface was 96%, and the shortest distance of the first concave portions was 2 μm. Sample 6 was molded in which the conditions of injection molding were adjusted so that the ratio of the area of the first concave portions to the area of the entire antireflection surface was 9%, and the shortest distance of the first concave portions was 110 μm. In sample 5, the free surface 41 was hardly formed on the antireflection surface. In sample 6, most of the antireflection surface was the free surface 41, and the first concave portions 12 having small sizes were dispersed in the antireflection surface. Sample 5 is similar to the conventional structure in which only a simple fine rough surface is formed without the free surface 41. The sample 6 has a structure in which most of the antireflection surface is the free surface 41, and it is difficult to form the first concave portion 12 having the second concave portion 31 to reduce the reflection of stray light.

The antireflective properties of the samples were evaluated by measuring the specular reflectance of the antireflective surface of each sample. In fig. 17, the results of the antireflection performance are represented by letters a (excellent), B (good), and C (acceptable). Further, the results of the durability of the samples are expressed by letters a (excellent), B (good) and C (acceptable). The durability test is as follows: the silicon paper sheet was impregnated with ethanol, then the antireflective surface of each sample was wiped 50 times with a force of 250gw to generate friction on the antireflective surface, and then the specular reflectance was measured again to evaluate whether the antireflective properties had changed.

In the sample 5 in which only the fine rough surface was formed without the free surface 41, since most of the antireflection surface was the first concave portion 12, good antireflection performance was obtained. However, the antireflective performance of the sample 5 may deteriorate after wiping because the second concave portion 31 may be damaged or worn. In sample 6 in which most of the antireflection surface was the free surface 41, sufficient antireflection performance was not obtained. However, the antireflection performance hardly changes after the wiping because the free surface 41 well protects the first concave portion 12 located lower than the free surface 41 and having the second concave portion 31.

In samples 1 to 4, since the free surfaces 41 are distributed so that the first concave portion 12 is surrounded by the free surfaces 41 of the antireflection surface, the antireflection performance of these samples is excellent or good. In addition, after wiping the antireflective surface, the antireflective properties of these samples hardly changed, and thus exhibited sufficient durability. Of these samples, sample 4 exhibited excellent (a) antireflective properties, and sample 3 exhibited excellent (a) durability.

Fig. 30 is a table showing the antireflective properties and durability of samples 7, 8, 9, 10, 11, and 12. The samples were various resin parts molded with various values of fillers in mass percentage. In fig. 30, the evaluation results are represented by letters a (excellent), B (good), and C (acceptable) in the same manner as in fig. 17. In addition, the constant pressure condition in the injection molding and the injection molding condition such as the temperature of the molten resin are the same as the conditions described with reference to fig. 17.

Sample 7 of fig. 30 was molded, in which the resin material was prepared such that the ratio of the content of the filler to the entire resin material was 5 mass%, and the Spc value of the surface roughness of the free surface was 1500. Sample 8 was molded in which a resin material was prepared such that the ratio of the content of the filler to the entire resin material was 15 mass%, and the Spc value of the surface roughness of the free surface was 3000. Sample 9 was molded in which a resin material was prepared such that the ratio of the content of the filler to the entire resin material was 30 mass%, and the Spc value of the surface roughness of the free surface was 6500. A sample 10 was molded in which a resin material was prepared such that the ratio of the content of the filler to the entire resin material was 45 mass%, and the Spc value of the surface roughness of the free surface was 9000.

Sample 11 was molded in which a resin material was prepared such that the ratio of the content of the filler to the entire resin material was 4 mass%, and the Spc value of the surface roughness of the free surface was 1450. Sample 12 was molded in which the resin material was prepared such that the ratio of the content of the filler to the entire resin material was 46 mass%, and the Spc value of the surface roughness of the free surface was 9100. Sample 11 had a free surface 41 that was hardly rough. Sample 12 had a free surface 41 with an Spc value of 9100 or higher. In sample 12, since the surface roughness of the free surface is large, although reflection of stray light can be sufficiently suppressed, durability may be deteriorated. In addition, when the ratio of the content of the filler with respect to the entire resin material exceeds 46 mass%, the resin material of the mold will not sufficiently flow in the injection molding, so that the quality of the appearance may be deteriorated.

As described above, the antireflective surface of the resin member of the present example has a structure in which the fine rough surface 23 formed by the second concave portions 31 is formed on each of the first concave portions 12. With this structure, excellent shielding effect and antireflection performance for stray light can be achieved. In addition, in the antireflective surface of the resin member of the present example, since the free surfaces 41 are distributed such that the first concave portion 12 is surrounded by the free surfaces 41, the fine rough surface 23 formed on the inner surface of the first concave portion 12 can be effectively protected from the wiping. That is, the present example can provide a resin member having an antireflection surface that can be simply manufactured at low cost, has good durability, generates less dust, and has good antireflection performance.

Second example

In the first example, injection molding is performed to transfer the shape of the mold surface to the antireflective surface of the resin member. However, as described below, molding using a roll mold instead of injection molding may be used to transfer the shape of the mold surface to the antireflective surface of the resin member.

In fig. 23, a laser beam 3003 for processing is reduced in diameter of its cross section by a lens 3004, and an irradiation area 3005 of the surface of a cylindrical die (rolling die) 3018 is irradiated with the laser beam 3003. The die 3018 is rotated toward a direction indicated by an arrow R1 by a driving mechanism (not shown), and reciprocated along a direction 3019 so that the laser beam can scan the surface of the die 3018. Scanning of the mold surface in direction 3019 can be performed by galvanometer mirrors such that laser beam 3003 scans the mold surface. By this operation, the surface of the cylindrical die 3018 can be roughened in accordance with the same processing principle as described above.

The irradiation condition of the pulse laser 3003 can be determined by the method described with reference to fig. 8, and a fine rough surface and a large uneven structure can be formed on the surface of the cylindrical mold by the processes shown in fig. 19A to 19D.

Fig. 24 shows a mold (rolling mold) 3018 that transfers the shape of the mold surface formed in the above-described manner to the antireflection surface of the resin material 3022. Although only a part of the resin material 3022 is illustrated in fig. 24, the resin material 3022 is a sheet that is usually rolled continuously and without interruption.

The resin material 3022 is conveyed toward the direction indicated by an arrow 3023 by a conveying mechanism (not shown). At this time, the resin material 3022 passes through the space between the cylindrical die 3018 (the surface of which has been worked in the above-described manner) and the opposite cylindrical roll die 3024, the roll die 3024 being rotated in accordance with the rotation of the die 3018. The two cylindrical dies 3018 and 3024 are urged toward the pressure contact direction by urging means (not shown), and the cylindrical die 3018 is rotated in a direction opposite to the rotation direction in which the cylindrical die 3024 is rotated. The cylindrical dies 3018 and 3024 are rotated in their rotational direction in which the resin material 3022 is pulled into the space between the dies 3018 and 3024 and the resin material 3022 is sent out toward the side opposite to the side where the resin material 3022 has been conveyed. The mold surface 3021 of the cylindrical mold 3018 is roughened in the manner described above. Here, the surface of the cylindrical die 3024 is not roughened in fig. 24. However, the surface of the cylindrical mold 3024 may also be roughened to transfer the shape of the surface of the mold 3024 to the back surface of the resin material 3022. For example, the shape of the surface of mold 3024 may be different from the shape of the surface of mold 3018.

In addition, the gap between the two cylindrical dies 3018 and 3024 is smaller than the thickness of the resin material 3022 obtained before the resin material 3022 passes through the space between the two cylindrical dies 3018 and 3024. By setting the gap between the dies 3018 and 3024, the pressure applied when the shape of the die surface 3021 is transferred to the resin material 3022 can be set. Here, the pressure corresponds to a constant pressure applied in the above-described injection molding. As the gap between dies 3018 and 3024 decreases, the pressure with which the shape of die surface 3021 is transferred to resin material 3022 increases.

Preferably, the gap between the two cylindrical dies 3018 and 3024 is adjusted by an adjustment mechanism (not shown). Therefore, by adjusting the pressure at which the shape of the mold surface 3021 is transferred to the resin material 3022, the distribution of the free surface 41 and the first concave portion 12 can be determined. In addition, the shape of the mold surface is easily transferred to the resin material 3022 at high temperature. Therefore, the resin material 3022 and the cylindrical dies 3018 and 3024 can be heated by a heating mechanism (not shown) in accordance with the composition of the resin material 3022, and the shape of the die surface 3021 of the die 3018 can be transferred to the resin material 3022 at high temperature.

Fig. 25A to 25C schematically illustrate a transfer state obtained when the pressure of the shape of the transfer mold surface 3021 is changed by adjusting the gap between the molds 3018 and 3024. Fig. 25A to 25C correspond to fig. 20A to 20C, and fig. 20A to 20C illustrate the transfer state obtained in the above-described injection molding.

In fig. 25A, reference numeral 2514 denotes a cross section of the surface of the cylindrical mold, and the surface of the cylindrical mold is roughened by a short pulse laser so that the concave-convex structure and the small concave-convex portion are combined. Resin material 2512 corresponds to resin material 3022 of fig. 24. In fig. 25A, the resin material 2512 contacts the convex portion of the mold 2514, but does not contact the concave portion of the mold 2514. As a result, a space 2515 is formed between the resin material 2512 and the concave portion of the mold 2514.

In fig. 25B, since the gap between the two cylindrical dies 3018 and 3024 of fig. 24 is smaller than that of fig. 25A, the pressure of the shape of the transfer die surface 3021 increases. Similar to fig. 25A, resin material 2512 contacts the convex portions of mold 2514, but does not contact the concave portions of mold 2514. As a result, a space 2515 is formed. However, space 2515 is smaller than that of FIG. 25A because the pressure applied by dies 3018 and 3024 (FIG. 24) increases.

In fig. 25C, since the gap between the dies 3018 and 3024 (fig. 24) is smaller than that of fig. 25B, the pressure of transferring the shape of the die surface 3021 further increases. In fig. 25C, similar to fig. 25A and 25B, resin material 2512 contacts the convex portion of mold 2514, but does not contact the concave portion of mold 2514. As a result, a space 2515 is formed. However, space 2515 is smaller than that of fig. 25A and 25B because the pressure applied by dies 3018 and 3024 (fig. 24) is further increased.

As described above, when the shape of the mold surface is transferred to the antireflection surface by using the roll mold, the gap between the molds 3018 and 3024 can be controlled as in the method of controlling the constant pressure in the injection molding (fig. 24). For example, by controlling the gap between the molds 3018 and 3024 (fig. 24), the first concave portions 12 and the free surfaces 41 surrounding the first concave portions 12 can be formed on the antireflection surface with a desired distribution and area ratio as in injection molding.

Third example

In a third example, a lens barrel of an optical apparatus and a container of an optical system will be described. Examples of the container include a support member such as a mirror holder, and the lens barrel and the container are one example of the article of the present invention.

Fig. 27 shows a configuration of a digital single lens reflex camera which is an optical apparatus including a resin part as a light shielding member, the resin part having an antireflection surface of the present embodiment. In fig. 27, an imaging lens 601 is attached to a camera body 602. Light from a subject is captured via optical elements (e.g., lenses 603 and 605) disposed on the optical axis of the imaging optical system of the imaging lens 601. Specifically, the lens 605 is supported by the inner barrel 604 so that the lens 605 can move relative to the outer barrel of the imaging lens 601, thereby performing focusing or zooming.

When the user observes the subject before taking an image of the subject, a part of light from the subject is reflected from the main mirror 607, passes through the prism 611 and the finder lens 612, and reaches the user. The main mirror 607 is a half mirror, and light having passed through the main mirror 607 is reflected from the sub-mirror 608 toward an Auto Focus (AF) unit 613. The light reflected from the sub-mirror 608 is used to measure distance. When an image is captured, the main mirror 607 and the sub-mirror 608 are moved out of the optical path by a drive mechanism (not shown), the shutter 609 is opened, and light from the imaging lens 601 forms an image thereof on the imaging element 610. The diaphragm 606 can change the brightness and the depth of focus for capturing an image by changing the area of the hole of the diaphragm 606.

When a film-based camera is used, the imaging element 610 of the single-lens reflex camera of fig. 27 is replaced by an area through which a silver halide film is placed and moved. The imaging lens 601 may be fixed to the camera body 602, but in an optical apparatus such as a camera, the imaging lens may be an interchangeable lens that can be detachably attached to the camera body 602.

The main mirror 607 is attached to the main mirror holder 640 via an adhesive material and supported by the main mirror holder 640. When no image is captured, the main mirror 607 and the main mirror holder 640 of fig. 27 are positioned at a position where the main mirror 607 will reflect a part of light toward the finder lens 612. When an image is captured, the main mirror 607 and the main mirror holder 640 are simultaneously swung to the horizontal position shown in fig. 27 by a drive mechanism (not shown) at the time of opening the shutter 609, as indicated by an arrow. At this time, in synchronization with the swinging of the main mirror 607, the sub-mirror 608 is closed so as to be flush with the main mirror holder 640.

The main mirror holder 640 is swung to move the main mirror 607 out of the optical path for taking an image and to block the optical path between the finder lens 612 and the main mirror 607 to prevent ghost caused by light from the finder lens 612. When an image is captured, the imaging element 610 is exposed for a necessary time, and then the shutter 609 is closed. When the shutter 609 is closed, the main mirror holder 640 quickly returns the main mirror 607 to the position of fig. 27 to allow the user to see an image through the finder lens 612. Therefore, the main mirror 607 moved by the main mirror holder 640 is referred to as an instantaneous return mirror.

In such an optical device of fig. 27, the resin member having the antireflection surface of the present invention may be used for the lens barrel of the imaging lens 601, particularly for the inner barrel 604 and the outer barrel of the imaging lens 601 supporting the inner barrel 604. Here, the imaging lens 601 may be fixed to the camera body, or may be an interchangeable lens. When the resin member is used for the inner barrel 604 accommodating the lens 605 serving as an optical element, the antireflection surface of the resin member faces the optical axis of the optical system including the optical element.

The optical system for capturing an image includes, in addition to the imaging lens 601, a light shielding chamber of the camera body 602 through which light passes to capture an image, as described above. The light shielding chamber of the camera body 602 is a container that needs to be shielded from light, and therefore a resin member having an antireflection surface of the present invention can also be used for the container. Specifically, the resin member of the present invention may be used for the inner wall of the light shielding chamber of the camera body 602. In this case, the antireflection surface of the resin member faces the optical path of the optical system of the light shielding chamber.

The receptacle of the optical system of the optical device of fig. 27 may include a support member, such as a primary mirror support 640. For example, edge portions of the front surface and the rear surface of the main mirror holder 640 are portions on which the main mirror 607 and the sub-mirror 608 are not disposed. These parts need to have an anti-reflection surface and reflect as little light as possible. Therefore, the resin member of the present invention can also be used for a container of an optical system, particularly for a support member such as the main mirror holder 640. Specifically, the antireflection surface of the resin part may be formed on a portion of the support member on which the main mirror 607 and the sub-mirror 608 are not provided. For example, the antireflection surface may be formed on edge portions of the front surface and the rear surface of the support member.

OTHER EMBODIMENTS

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.