1. Field of the Invention
The present invention relates to a stamper used as a mold in manufacturing a molding, a stamper manufacturing method, and a molding manufacturing method.
2. Description of the Related Art
In the past, there has been proposed an optical device such as a lens including an antireflective structure on a surface thereof. In an antireflective structure, conical, convex-concave shaped bodies are arranged in array at intervals equal to or lower than a wavelength of incident light (at submicron intervals in a case of visible light, for example) (see, for example, Japanese Patent Application Laid-open No. 2006-130841 (hereinafter, referred to as Patent Document 1)).
In a method of manufacturing an antireflective structure shown in
In the optical device disclosed in Patent Document 1, the acicular crystal is pointed only in one direction due to constraints of principles of an etching process. Therefore, the reflection of light that has entered the optical device mainly in an optical axis direction can be reduced, but the reflection of incident light having an angle with respect to the optical axis cannot be reduced.
On the other hand, Japanese Patent Application Laid-open No. 2008-37089 (hereinafter, referred to as Patent Document 2) discloses an optical device on a convex surface of which a convex-concave structure for antireflection is formed (
However, Patent Document 2 discloses that the molds having the convex-concave structures are formed by sputtering and etching processes. It is not realistic to perform an exposure and an etching so that the convex-concave structures are each formed on a curved surface of the mold for manufacturing the optical device shown in
In view of the above-mentioned circumstances, it is desirable to provide a stamper, a stamper manufacturing method, and a molding manufacturing method capable of realizing a product in which a predetermined pattern structure is formed on a nonplanar surface and improving the productivity of the product.
According to an embodiment of the present invention, there is provided a method of manufacturing a stamper. The method includes setting a straight plate member to a die, the plate member having a formation surface on which a predetermined pattern structure is formed and an opposite surface thereof, so as to cause the opposite surface to face a cavity of the die.
The method includes feeding a continuous body into the cavity from a side of the formation surface of the plate member and pressurizing the plate member with the continuous body, to deform an entire shape of the formation surface of the plate member set to the die into a shape corresponding to the cavity.
That is, the formation surface of the plate member, on which the pattern structure is formed, is formed into a shape corresponding to the cavity with the continuous body being as a core. With this structure, for example in a case where the inner surface of the cavity has a nonplanar shape, the entire shape of the formation surface is formed into a curved surface shape, with the result that a stamper having a predetermined pattern structure formed on the nonplanar surface can be manufactured. As a result, by forming a molding target object by using the stamper, it is possible to manufacture a product (molding) on a surface of which the pattern structure corresponding to the pattern structure of the stamper formed. Therefore, it is possible to manufacture products in a large quantity at a low cost and in a short time, which can improve the productivity.
The nonplanar surface includes a curved surface and a surface in combination with two or more planes. The curved surface includes a spherical surface, a non-spherical surface, and the like.
The continuous body may be a resin.
The method of manufacturing a stamper may further include modifying a shape of an inner surface of the cavity of the die after the plate member is pressurized. In this case, the stamper formed by the pressurization is set to the die having the modified shape of the inner surface of the cavity. In addition, in order that the entire shape of the formation surface of the stamper is deformed into a shape corresponding to the modified cavity of the die, the stamper is pressurized by the continuous body fed into the cavity.
That is, the molding target object is formed by using the stamper formed first. If it is necessary to modify the shape of the molding, the shape of the stamper formed first is modified. In this case, the inner surface of the cavity is modified, and the stamper is formed with the die again, thereby making it possible to modify the shape of the stamper. As a result, the manufacturing cost of the stamper can be cut.
The stamper may be a stamper used for forming an optical device having an optical pattern structure corresponding to the pattern structure. For example, as the optical pattern structure, a structure that exerts an antireflection function, such as a convex-concave structure, may be used.
The die may be a direct gate type. That is, a die in which a sprue is directly connected to a gate without a runner may be used. With this structure, it is possible to improve a uniformity of the pressure that is applied to the plate member in the cavity by the continuous body as the core.
According to another embodiment of the present invention, there is provided a stamper manufactured by the manufacturing method described above.
According to another embodiment of the present invention, there is provided a method of manufacturing a molding. The method includes preparing a stamper formed by setting a straight plate member to a die, the plate member having a formation surface on which a predetermined pattern structure is formed and an opposite surface thereof, so as to cause the opposite surface to face a cavity of the die and pressurizing the plate member with a continuous body fed into the cavity of the die from a side of the opposite surface of the plate member, to deform an entire shape of the formation surface of the plate member into a shape corresponding to the cavity of the die.
The method includes forming a mold target object having a structure corresponding to the pattern structure by using the stamper.
As described above, according to the embodiments of the present invention, it is possible to realize the product in which the predetermined pattern structure is formed on the non-planar surface and improve the productivity of the product.
These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of best mode embodiments thereof, as illustrated in the accompanying drawings.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
(Stamper Manufacturing Method 1)
In the following embodiment, a description will be given on a manufacturing method of a stamper for manufacturing an optical device as a product (molding). As an example of an optical device, typically, a lens having a moth-eye structure as a minute convex-concave structure as a predetermined pattern structure is given.
(Manufacturing Method of Master)
As shown in
(Manufacturing Method of Stamper for Convex Lens)
Further, as shown in
In the process shown in
In the exposure process of
In the PTM technique, an optical pickup of an optical disc drive is used as an exposure system, for example. Specifically, for example, a quartz glass substrate is rotated, and a laser light source of the optical pickup emits laser light. In accordance with the modulation of the intensity of light, a resist on the quartz glass substrate rotated is subjected to a selective exposure, thereby forming a predetermined latent image pattern on the resist. By using the PTM technique, the latent pattern can be formed in a short time.
In the electroforming used in the process of
A stamper die 10 includes a movable plate 2 and a fixed plate 4. The movable plate 2 is equipped with a reception piece 6, and the fixed plate 4 is equipped with a sprue bush 8. The reception piece 6 is detachably attached to the movable plate 2 with a screw or another mounting fixture. The sprue bush 8 is also detachably attached to the fixed plate 4 with a screw or another mounting fixture. The plate member 5 is provided to the reception piece 6 so that the plate member is sandwiched between the reception piece 6 and the sprue bush 8, thereby setting the plate member 5 to the stamper die 10.
On the side of the sprue bush 8 of the reception piece 6, a cavity 7 for forming the plate member 5 into a desired shape is formed. The plate member 5 is disposed to face the cavity 7. The sprue bush 8 has a feed port 8a, a sprue 8b, a gate 8c, and a diffusion area 8d. From the feed port 8a, for example, a resin as a continuous body is fed as described later. The sprue 8b is communicated with the feed port 8a. The gate 8c is formed at an end portion of the sprue 8b. The diffusion area 8d diffuses the fed resin. The diffusion area 8d is larger than the diameter of a flow path of the sprue 8b. The plate member 5 is set so as to cause the formation surface 52 (see,
In this embodiment, as the stamper die 10, a direct-gate type is used. That is, a runner is not provided, and the sprue 8b is directly connected to the gate 8c, with the result that it is possible to improve the uniformity of a pressure that is applied to the plate member 5 in the cavity 7 by the resin as a core.
The diffusion area 8d of the sprue bush 8 is provided to be opposed to the cavity 7. The diffusion area 8d is an area used for pressurizing the plate member 5 by the resin fed therein. In the diffusion area 8d, the pressure applied by the resin is uniformly given to the entire area of the plate member 5 that is required to be deformed. Further, in the stamper die 10, the center axis of the cavity 7, the center axis of the diffusion area 8d, and the center of the gate 8c are substantially coincided with one another. As a result, the uniformity of the pressure applied to the plate member 5 by the resin discharged from the gate 8c is increased.
It is to be noted that the diffusion area 8d may not be provided. In this case, the diameter of an opening of the gate 8c can be designed to be an appropriate size so that the pressure of the resin is uniformly given to the plate member 5.
As shown in
In a state shown in
As described above, the formation surface 52 of the plate member 5, on which the moth-eye structure is formed, is formed into the spherical surface corresponding to the shape of the cavity 7 of the stamper die 10 with the resin 13 that is the continuous body used as the core. Because the entire shape of the formation surface 52 is formed into the spherical shape, the stamper 5′ having the moth-eye structure formed on the spherical surface can be manufactured. As a result, by forming an optical device by using the stamper 5′, it is possible to manufacture a lens product having a surface of a moth-eye structure corresponding to the moth-eye structure 51 of the stamper 5′. Thus, it is possible to manufacture products in large quantity at a low cost in a short time, with the result that the productivity can be increased.
In particular, by the manufacturing method of this embodiment, all the protrusions of the moth-eye structure 51 are substantially directed in a direction normal to the sphere of the formation surface 52. Thus, it is possible to increase a range of an incident angle of incident light, in which an antireflection effect can be exerted. As a result, in a case where a convex lens formed by the stamper 5′ is mounted on a camera or the like, it is possible to further reduce a flare or a ghost at the time of shooting by the camera as compared to a product in related art.
Hereinafter, a description will be given on a result of a manufacturing test of the stamper 5′ conducted by the inventor of the present invention.
In
In the stripping process, the stamper 5′ receives a force in a direction in which the resin 13 is distanced from the stamper 5′. Because the stamper 5′ is thin, elastic deformation of the stamper 5′ occurs, and the stamper 5′ follows the movement of the resin 13. That is, even if each of the protrusions is directed in the normal direction as shown in
(Manufacturing Method of Convex Lens)
The stamper 5′ manufactured as described above is prepared and set to a lens mold 60 shown in
(Method of Modifying Shape of Stamper)
Next, a description will be given on an example of modifying the shape of the stamper 5′. The shape of the lens often requires to be partly modified in processes of designing and manufacturing the lens.
For example, a description will be given on a case where a part of a convex lens 24 formed as a molding, specifically, for example, a part A surrounded by the dash-dotted line in the figure is thickened, thereby modifying a curvature of the convex lens 24 as shown in
As shown in
According to this embodiment, there is no need to produce the stamper 5′ again from the beginning. By modifying the inner surface shape of the cavity 7 of the reception piece 6, the shape of the stamper 5′ can be repeatedly modified in a short time. As a result, the manufacturing cost of the stamper 5′ can be cut.
It is to be noted that, at the time of modifying the stamper 5′ as described above, the stamper 5′ is set to the lens mold 60 shown in
(Stamper Manufacturing Method 2)
(Manufacturing Method of Stamper for Concave Lens)
A stamper die 20 is provided with a movable plate 42 and a fixed plate 44. The movable plate 42 is provided with a reception piece 46, and the fixed plate 44 is provided with a sprue bush 48. The sprue bush 48 may be the same as the sprue bush 8 shown in
By forming a mold target by using the stamper 5″ manufactured as described above, the concave lens having the plurality of protrusions in the normal directions to the concave surface can be manufactured.
The embodiment of the present invention is not limited to that described above, and other various embodiments can be conceived.
In the stampers 5′ and 5″, the pattern structure such as the moth-eye structure is formed on the spherical surface. That is, for example, in
In the above embodiment, as the molding to be a product, the optical device having the moth-eye structure is used, but the structure is not limited to the moth-eye structure, and an optical device having various pattern structures formed on a nonplanar surface may be used as an example. In addition, as the product, the lens is used as an example in the above embodiment, but the stamper and the manufacturing method of the stamper according to the embodiment can be applied to another optical device such as an optical sheet having a nonplanar surface.
In the above embodiments, the example in which the lens as the resin product is formed by using the stamper 5 is described, but the lens is not limited to the resin product and may be a glass product.
In addition to the optical device, in a case where a petri dish or the like for cell culture that is used in a biotechnology field or the like is manufactured, the stamper 5″ according to the above embodiment can be applied. In this case, the entire shape of the surface is a nonplanar surface, and a petri dish having a minute convex-concave structure in which cells are contained is formed with the stamper 5″. Further, as an example of the pattern structure other than the moth-eye structure, a pattern of an electric circuit may be given.
In the above embodiment, the intervals of the protrusions of the moth-eye structure are set to several hundreds nanometers that is equal to the wavelength (or half the wavelength) of visible light, for example, 200 to 300 nm. However, in a case where the pattern structure other than the moth-eye structure, such as the electric circuit, is applied, the intervals in the pattern structure may be set so that the patterns can be visually confirmed, for example, set to be 0.1 mm or more, several millimeters or more, or less than 200 to 300 nm.
As the continuous body, the resin 13 that is a solid is used, but a fluid such as a liquid and a gas may instead be used. As an example of the liquid, oil or the like may be used. As an example of the gas, air, an inert gas, or the like may be used.
In the above embodiment, the description is given on the example in which one lens is formed. However, a form in which a plurality of lens are formed at the same time like a compound eye lens may be used. In this case, by the manufacturing method described with reference to
In the above embodiment, the stamper die 10 and the lens mold 60 differ from each other, but may be the same.
The present application contains subject matter related to that disclosed in Japanese Priority Patent Application JP 2009-113284 filed in the Japan Patent Office on May 8, 2009, the entire content of which is hereby incorporated by reference.
Number | Date | Country | Kind |
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2009-113284 | May 2009 | JP | national |