WO2008059712A1

WO2008059712A1 - Optical element, transfer mold, method for manufacturing transfer mold, and method for manufacturing optical element

Info

Publication number: WO2008059712A1
Application number: PCT/JP2007/071108
Authority: WO
Inventors: Renzaburo Miki; Kazuya Ikuta
Original assignee: Sharp Kabushiki Kaisha
Priority date: 2006-11-17
Filing date: 2007-10-30
Publication date: 2008-05-22
Also published as: JP4108722B2; JP2008129197A

Abstract

This invention provides an optical element. An optical element (1)in one embodiment is a synthetic resin, for example, plastic lens comprising an antireflection layer (12) provided on the surface of a basic resin part (11) formed by resin molding. The antireflection layer (12) is formed of an inorganic material and is divided into a plurality of parts by fine protrusions (13) projected from the surface of the basic resin part (11). Namely, the antireflection layer (12) is divided into appropriate regions on the surface of the optical element (1) so as to correspond to the arrangement of the fine protrusions (13).

Description

Specification

Optical element, transfer mold, transfer mold manufacturing method, and optical element manufacturing method

[0001] The present invention relates to an optical element made of synthetic resin on which an antireflection layer is formed, a transfer mold for manufacturing such an optical element, a transfer mold manufacturing method for manufacturing such a transfer mold, and The present invention relates to an optical element manufacturing method for manufacturing such an optical element.

Background art

Conventionally, in a synthetic resin optical lens formed of a synthetic resin such as a plastic lens, a thin film of silicon oxide (SiOx) is provided to prevent reflection on the surface of the optical lens. Alternatively, a thin film of a high refractive index material such as titanium oxide (TiO 2), zirconium oxide (ZrO 2), calcium oxide (CaO 2), tantalum oxide (Ta 2 O 3), or a thin film of a low refractive index material such as a silicon oxide (SiO 2). It has been proposed to provide a multilayer antireflection layer in which and are laminated alternately.

[0003] As Conventional Example 1, a quarter-wave film (hereinafter referred to as a λ / 4 film) made of SiO having a refractive index n of 1.55 or more and a thickness force of 9 nm or less is deposited on the surface of an acrylic lens. In addition, a two-layer antireflection layer is proposed in which a film of refractive index n of 1.38 // 4 film made of magnesium fluoride (MgF) is laminated thereon (see, for example, Patent Document 1). .

As a conventional example 2, a thin film having a refractive index n = l. 47, a film thickness d = 354 nm, an optical film thickness nd = 0 (design wavelength 0 = 520 nm) as a first layer is vacuumed as the first layer. It is formed by vapor deposition, on which a J jet, Ta O force, a refractive index of η = 2 · 05, an optical film thickness of nd = 0.057 λ θ, and Si

Thin film with refractive index n = l. 47 with optical force nd = 0.11 λ θ and thin film with refractive index n = 2.05 with optical force nd = 0.538 λ θ And an antireflection layer having a five-layer force in which thin films having a refractive index of n = l.47 and an optical film thickness of nd = 0.258 λθ are also proposed (for example, see Patent Document 2) .)

[0005] As Conventional Example 3, a refractive index η = 1.60 made of SiOx as a first layer on a methacrylic resin cast substrate, optical film thickness nd = (0/4) X 20% (d = 17-; 18 nm ) Is formed by vacuum deposition (design wavelength λ 0 = 550 to 570 nm), and on top of that, the refractive index η = 1 · 95, a thin film with an optical film thickness of nd = (0/4) X 20%, a thin film with a refractive index n = 1.45 consisting of S ^, and an optical film thickness of nd = (λ 0/4) X 40%, TiO force, refractive index η = 2.0, optical film thickness nd = (λ θ / 4) X 70% thin film, SiO force refractive index η = 1 45, optical film thickness nd = (0 / 4) An antireflection layer composed of a five-layer film in which thin films of X 95% are laminated has been proposed (for example, see Patent Document 3).

[0006] However, in Conventional Example 1 to Conventional Example 3, when used in a limited environment such as a residential space, there is no possibility that the performance will deteriorate significantly due to misalignment! / If the product is exposed to severe and temperature conditions, or used for a long period of time in an environment where the temperature or humidity varies greatly, the wear resistance or chemical resistance will deteriorate, or the synthetic resin material and inorganic antireflection layer Cracks (film cracks) may occur in the antireflection layer due to the thermal strain of the base material of the synthetic resin resulting from the difference in expansion coefficient, and in the worst case, the antireflection layer may peel off. Under such circumstances, an improved conventional example has been proposed to solve the problems of Conventional Example 1 to Conventional Example 3.

FIG. 9 is a cross-sectional view showing a state of an antireflection layer of an optical component according to an improved conventional example. In order to make the drawing easy to see, hatching is omitted in some cross sections.

[0008] In this improved conventional example, the synthetic resin lens 130, which is an optical component (optical element), has a high chemical resistance and high adhesion to the synthetic resin. SiOx (2) It is proposed to use a thin film composed mainly of x> l) as the undercoat 131 which does not participate in antireflection properties. This improves the wear resistance of the antireflection multilayer film 132 and improves the chemical resistance and adhesion to the synthetic resin lens 130 (see, for example, Patent Document 4).

[0009] This synthetic resin lens 130 has sufficiently improved wear resistance and chemical resistance by making the film thickness of the undercoat 131 not less than 200 nm and not more than 300 nm. It also improves durability in harsh environments, making it difficult for cracks and delamination of the antireflection multilayer film 132 to occur. The antireflection multilayer film 132 includes a first antireflection layer 132a made of a high refractive index material, a second antireflection layer 132b made of a low refractive index material, and a third antireflection layer made of a high refractive index material. 132c, and a fourth antireflection layer 1 32d made of a low refractive index material. [0010] On the other hand, an optical element using a synthetic resin optical material having heat resistance so as to be compatible with a batch reflow mounting process of a mopile apparatus for an optical element made of a synthetic resin used in the field of mopile equipment in recent years Is desired. However, the synthetic resin optical material with heat resistance has a larger linear expansion coefficient than the conventional synthetic resin optical material, and the environment for performing the material reflow mounting process. Since the temperature can be as high as 250 to 270 ° C, even if an undercoat (underlayer) based on the technique described in Patent Document 4 is provided, deformation of the antireflection layer (cracks, film peeling, etc.) will occur. There's a problem.

Patent Document 1: JP-A-60-98401

Patent Document 2: JP-A-60-225101

Patent Document 3: Japanese Patent Laid-Open No. 3-116101

Patent Document 4: JP-A-6-273601

Disclosure of the invention

Problems to be solved by the invention

The present invention has been made in view of such a situation, and has a highly reliable optical technology that can suppress deformation of the antireflection layer by providing an antireflection layer divided on the surface of the basic resin portion. An object is to provide an element.

In addition, the present invention includes a basic resin portion and a fine protrusion by providing a basic transfer portion that resin-molds the basic resin portion and a projection transfer groove that resin-molds the fine protrusion that divides the antireflection layer. It is an object of the present invention to provide a transfer mold that can be molded simultaneously with resin and can manufacture high-precision optical elements with high productivity and low cost.

[0013] Further, the present invention provides a basic transfer portion forming step for forming a basic transfer portion for resin-molding the basic resin portion, and forming a protrusion transfer groove for resin-molding a fine protrusion portion by patterning the surface of the basic transfer portion. The present invention has an object to provide a transfer mold manufacturing method capable of easily and inexpensively manufacturing a high-precision transfer mold by forming a protrusion transfer groove easily and with high accuracy. To do.

[0014] The present invention further includes a resin molding step of resin-molding the basic resin portion and the fine protrusions, and an antireflection layer laminating step of laminating an antireflection layer on the surface of the basic resin portion. The antireflection layer can be accurately laminated by forming the part and the fine protrusion at the same time, An object of the present invention is to provide an optical element manufacturing method capable of manufacturing an optical element having excellent optical characteristics with high accuracy and high productivity.

Means for solving the problem

The optical element according to the present invention is an optical element made of a synthetic resin in which an antireflection layer is formed on the surface of a basic resin portion formed by resin molding, and the antireflection layer is formed of an inorganic substance. And is divided.

With this configuration, a highly reliable optical element capable of relieving internal stress generated due to a difference in linear expansion coefficient between the optical element and the antireflection layer and suppressing deformation of the antireflection layer, Become.

[0017] Further, in the optical element according to the present invention, the antireflection layer is divided by fine protrusions protruding from the surface of the basic resin part.

[0018] With this configuration, the expansion direction of the fine protrusions faces the expansion in the in-plane direction of the antireflection layer in a high-temperature environment, so that a compressive force is generated in the in-plane direction of the antireflection layer. It becomes possible to suppress deformation of the antireflection layer.

[0019] In the optical element according to the present invention, the cross-sectional shape of the fine protrusion in the direction intersecting the length direction of the fine protrusion is any of a semicircle, a triangle, and a trapezoid. It is characterized by being.

[0020] With this configuration, it is possible to secure the releasability from the transfer mold in resin molding and form the fine protrusions with high accuracy.

[0021] Further, in the optical element according to the present invention, the bottom width of the cross section is smaller than 2 ^ 111, and the height of the cross section is smaller than 2 m.

[0022] With this configuration, it is possible to prevent the scattering by the fine protrusions from affecting the optical characteristics of the optical element.

[0023] Further, in the optical element according to the present invention, the fine protrusions are arranged symmetrically with respect to the optical axis of the basic resin part.

[0024] With this configuration, the dividing lines can be arranged symmetrically with respect to the optical axis, so that it is possible to evenly relieve internal stress and to suppress deformation of the antireflection layer evenly and reliably. It becomes possible. In the optical element according to the present invention, the fine protrusions are arranged concentrically and radially with respect to the optical axis of the basic resin part.

[0026] With this configuration, the internal stress relaxation can be evenly distributed with axial symmetry.

In addition, since it is possible to realize axial symmetry with a simple structure, it is possible to easily manufacture an optical element with little deformation.

[0027] Further, in the optical element according to the present invention, the fine protrusions are arranged in an outer peripheral region of the basic resin part away from the optical axis.

[0028] With this configuration, it is possible to prevent a decrease in optical characteristics in the central region around the optical axis of the optical element.

In the optical element according to the present invention, the antireflection layer is a low refractive index layer made of a material having a refractive index lower than that of the basic resin portion.

[0030] With this configuration, it is possible to suppress deformation of the antireflection layer in a higher temperature environment. Also, by using a single-layer structure, an increase in internal stress is prevented, and a process for manufacturing the antireflection layer The manufacturing cost can be reduced by simplifying the above.

[0031] In the optical element according to the present invention, the antireflection layer includes a low refractive index layer made of a material having a refractive index lower than that of the basic resin portion, and a refractive index of the basic resin portion. Further, it is characterized by a laminated structure in which high refractive index layers made of a material having a high refractive index are laminated.

With this configuration, an optical element having an excellent antireflection characteristic with an extremely low reflectance is obtained, and the force S can be obtained.

[0033] Further, in the optical element according to the present invention, an underlayer mainly composed of a key oxide is formed between the antireflection layer and the surface of the basic resin portion. .

[0034] With this configuration, the adhesion of the antireflection layer to the basic resin portion can be improved, and the chemical resistance and abrasion resistance of the optical element can be improved, so that the optical characteristics do not deteriorate. The optical element can be made high.

[0035] In addition, the transfer mold according to the present invention resin-molds an optical element including an antireflection layer separated by fine protrusions formed on the surface of a basic resin portion formed by resin molding. A transfer mold, comprising: a basic transfer portion for resin-molding the basic resin portion; and a protrusion transfer groove for resin-molding the fine protrusion portion.

[0036] With this configuration, the basic resin portion and the fine protrusion can be molded simultaneously, and a highly accurate optical element can be manufactured with high productivity and low cost.

[0037] The transfer mold manufacturing method according to the present invention also includes a transfer molding of an optical element having an antireflection layer separated by fine protrusions formed on the surface of a basic resin portion formed by resin molding. A transfer mold manufacturing method for manufacturing a mold, comprising: a basic transfer portion forming step for forming a basic transfer portion corresponding to the basic resin portion; and a protruding transfer groove corresponding to the fine protrusion portion. And a protrusion transfer groove forming step formed by patterning the surface of the substrate.

With this configuration, the protrusion transfer groove can be formed easily and with high accuracy, and a high-precision transfer mold can be manufactured easily and inexpensively.

[0039] Further, the optical element manufacturing method according to the present invention is an optical element manufacturing method for manufacturing an optical element including an antireflection layer separated by a fine protrusion formed on the surface of a basic resin portion formed by resin molding. A method comprising: a resin molding step of resin-molding the basic resin portion and the fine protrusions; and an antireflection layer laminating step of laminating an antireflection layer on the surface of the basic resin portion. .

[0040] With this configuration, the basic resin portion and the fine protrusions can be simultaneously formed and the antireflection layer can be accurately laminated, so that an optical element having high accuracy and excellent optical characteristics can be manufactured with high productivity. It becomes possible.

[0041] In the optical element manufacturing method according to the present invention, the antireflection layer is laminated by vapor deposition.

With this configuration, the film thickness of the antireflection layer can be accurately controlled, and an optical element having high-precision optical characteristics can be obtained.

The invention's effect

[0043] According to the optical element of the present invention, since the antireflection layer divided on the surface of the basic resin portion is provided, deformation (cracking, peeling, etc.) of the antireflection layer can be suppressed, and reliability is improved. When it becomes possible, it has a repulsive effect. [0044] Further, according to the transfer mold according to the present invention, since the basic transfer portion includes a basic transfer portion that resin-molds the basic resin portion, and a protrusion transfer groove that resin-molds a fine protrusion portion that divides the antireflection layer, It is possible to mold the basic resin portion and the fine protrusion at the same time, and it is possible to produce a high-precision optical element with high productivity and low cost.

[0045] Further, according to the transfer mold manufacturing method of the present invention, the basic transfer portion forming step for forming the basic transfer portion for resin-molding the basic resin portion and the protrusion transfer groove for resin-molding the fine protrusion portion are basically used. A projection transfer groove forming step that forms the surface of the transfer portion by patterning, so that the projection transfer groove can be formed easily and with high precision, and a high-precision transfer mold can be easily and inexpensively manufactured. It has a good effect.

[0046] Further, according to the optical element manufacturing method of the present invention, the resin molding step of resin-molding the basic resin portion and the fine protrusions, and the antireflection layer lamination in which the antireflection layer is laminated on the surface of the basic resin portion. Process, the basic resin portion and the fine protrusions can be formed at the same time, and the antireflection layer can be accurately laminated, and an optical element having high accuracy and excellent optical characteristics can be produced with high productivity. .

Brief Description of Drawings

1 is an explanatory view schematically showing the shape of an optical element according to Embodiment 1 of the present invention, FIG. 1 (A) is a perspective view, and FIG. 1 (B) is an optical axis of the optical element. It is sectional drawing which shows the state which cut | disconnected the fine projection part (circular projection part) in the plane containing γ.

FIG. 2 is a cross-sectional view schematically showing a cross section of a fine protrusion of the optical element according to Embodiment 1 of the present invention. FIG. 2 (A) is a semicircular cross section, and FIG. 2 (B) is a cross section. Fig. 2 (C) shows the case where the cross section is trapezoidal.

FIG. 3 is a perspective view schematically showing a modification of the shape of the optical element according to Embodiment 1 of the present invention.

FIG. 4 is a sectional view showing an example of the structure of an antireflection layer in an optical element according to Embodiment 2 of the present invention.

FIG. 5 is a cross-sectional view showing another structural example of the antireflection layer in the optical element according to Embodiment 2 of the present invention.

FIG. 6 is a perspective view schematically showing the shape of a transfer mold according to a third embodiment of the present invention. FIG. 7 is a cross-sectional view schematically showing the shape of the transfer mold in each step of the transfer mold manufacturing method according to Embodiment 4 of the present invention, and FIG. 7B shows a state in which the photoresist for forming the protrusion transfer groove is exposed, and FIG. 7C shows a state in which the resist mask is formed. Fig. 7 (D) shows the completed transfer mold, with the mold material etched to form protrusion transfer grooves.

FIG. 8A is a cross-sectional view showing a state where a transfer mold applied in the optical element manufacturing method according to Embodiment 5 of the present invention is opened.

FIG. 8B is a cross-sectional view showing a state in which a transfer mold applied in the optical element manufacturing method according to Embodiment 5 of the present invention is clamped and a synthetic resin is injected.

FIG. 8C is a cross-sectional view showing a state in which resin molding by a transfer mold applied in the optical element manufacturing method according to Embodiment 5 of the present invention is completed and the optical element is released.

FIG. 8D is a cross-sectional view showing a state in which an antireflection layer is formed on an optical element resin-molded by the optical element manufacturing method according to Embodiment 5 of the present invention.

FIG. 8E is a cross-sectional view showing a state in which the fine antireflection layer adhering to the fine protrusion is removed by the optical element manufacturing method according to Embodiment 5 of the present invention.

FIG. 8F is a cross-sectional view showing the state of the optical element completed by the optical element manufacturing method according to Embodiment 5 of the present invention.

FIG. 9 is a cross-sectional view showing a state of an antireflection layer of an optical component according to an improved conventional example. Explanation of symbols

1 Optical element

2 Transfer mold

2s transfer surface

11 Basic resin part

l lg gate mark

Hi center region

l is Peripheral area

12 Antireflection layer

12a Low refractive index layer 12b High refractive index layer

12c Low refractive index layer

13 Fine protrusion

13c Circular protrusion

13r Linear protrusion

15 Underlayer

20U upper mold

20L lower mold

23U upper body type

23L lower body type

27 Gate

21 Basic transfer section

22 Protrusion transfer groove

25 photoresist

25a Photoresist

25m resist mask

25w opening

30 Deposition chamber

40 High temperature chamber

Ect etching simultaneous IJ

Lax light car reason

Lex ife light

MC micro crack

RV Anti-reflective layer component vapor

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

An optical element according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is an explanatory view schematically showing the shape of the optical element according to Embodiment 1 of the present invention, in which FIG. 1 (A) is a perspective view and FIG. 1 (B) is the light of the optical element. It is sectional drawing which shows the state which cut | disconnected the fine protrusion part (circular protrusion part) in the plane containing an axis | shaft. Note that hatching indicating a cross section in FIG. 1B is omitted for easy viewing of the drawing.

In the optical element 1 according to the present embodiment, an antireflection layer 12 (not shown in FIG. 1 (A)) is formed on the surface of the basic resin portion 11 formed by resin molding. For example, it is configured as a plastic lens made of synthetic resin. The basic resin portion 11 is formed to have a structure (for example, a lens shape) that realizes the optical function of the optical element 1. In addition, as a synthetic resin constituting the basic resin portion 11, for example, an acrylic resin, a polycarbonate resin, a silicone resin having an alkyl group or a phenyl group, or an inorganic / organic hybrid silicone resin in which a carbon skeleton and a silicone skeleton are hybridized. Can be applied. The antireflection layer 12 is made of an inorganic material and divided.

[0053] With this configuration, when the optical element 1 is exposed to a high temperature environment, the internal stress generated over the entire optical element 1 due to the difference in linear expansion coefficient between the optical element 1 and the antireflection layer 12 is alleviated. It is possible to suppress the deformation of the antireflection layer 12 such as cracking and peeling.

The antireflection layer 12 is divided by fine protrusions 13 protruding from the surface of the basic resin part 11. That is, the fine protrusion 13 is formed with a height that is greater than the thickness of the antireflection layer 12. Therefore, the antireflection layer 12 is divided into appropriate regions on the surface of the optical element 1 corresponding to the arrangement of the fine protrusions 13.

[0055] Note that, under a high temperature environment, the antireflection layer 12 expands in the in-plane direction, but the fine protrusion 13 expands in a direction opposite to the expansion direction. Therefore, a compressive force is generated in the in-plane direction of the antireflection layer 12 and it is possible to suppress deformation of the antireflection layer 12.

[0056] Further, by arranging the fine protrusions 13 symmetrically with respect to the optical axis Lax of the optical element 1 (basic resin part 11) over the entire surface of the basic resin part 11, an antireflection layer due to thermal expansion is provided. It is possible to balance 12 deformations corresponding to the axial symmetry, and change them evenly and reliably. The shape can be suppressed.

[0057] In a high temperature environment, the optical element 1 expands toward the periphery of the optical element 1 around the optical axis Lax, but the fine protrusions 13 are arranged concentrically around the optical axis Lax. By adopting a configuration that has a circular protrusion 13c and linear protrusions 13r arranged radially about the optical axis Lax, the internal stress is evenly distributed with a simple structure and axial symmetry. (Hereinafter, when it is not necessary to distinguish between the circular protrusion 13c and the linear protrusion 13r, they are simply referred to as the fine protrusion 13).

That is, since the dividing lines (fine projections 13) can be arranged symmetrically about the optical axis Lax, the internal stress can be evenly distributed with axial symmetry, and the antireflection layer 12 It becomes possible to suppress deformation evenly and reliably.

In addition, by forming the fine protrusions 13 in a cylindrical shape and a radial shape, the fine protrusions 13 can be easily arranged with axial symmetry, and the antireflection layer 12 is less deformed and has high reliability. Element 1 can be manufactured easily.

[0060] It should be noted that the same action and effect can be obtained with respect to changes in humidity other than the force temperature described as the high temperature environment. Further, the optical characteristics of the optical element 1 do not deteriorate even in a high temperature environment in the process of mounting the optical element 1 on an electronic device or the like. For example, the batch reflow mounting process is not affected by the high-temperature environment, so that the optical element 1 with high productivity and reliability can be obtained.

FIG. 2 is a cross-sectional view schematically showing a cross section of the fine protrusion of the optical element according to Embodiment 1 of the present invention. FIG. 2 (A) is a semicircular cross section, and FIG. B) shows a triangular cross section, and Fig. 2 (C) shows a trapezoidal cross section. Note that hatching in the cross section is omitted.

The fine protrusion 13 preferably has a shape that gradually changes in order to reduce light scattering by the optical element 1 as much as possible. Further, since the fine protrusion 13 is resin-molded together with the resin molding of the basic resin portion 11 on the surface of the optical element 1 by a transfer mold 2 (see Embodiment 3 and below) described later, the transfer mold It is desirable that the shape does not affect the mold 2 releasability.

Therefore, it is desirable that the cross-sectional shape in the direction intersecting the length direction of the fine protrusions 13 is a semicircular shape, a triangular shape, or a trapezoidal shape (rectangular shape). With this configuration, it is possible to form the fine protrusion 13 with high accuracy while ensuring releasability from the transfer mold 2 in resin molding. It becomes.

[0064] Desirably, the dimensions (bottom width W and height H) of the cross-section of the fine protrusions 13 are such that they do not affect the optical characteristics of the optical element 1! /. In order to make the dimensions completely unaffected, the length of the shortest wavelength of the wavelength band in which the optical element 1 is used needs to be smaller. For example, when the wavelength band used is the visible light region (short wavelength side: 380 to 400 m, long wavelength side: 750 to 800 111), the base width W and height H are 400 nm or less. However, this numerical value is somewhat larger when the reduction in the amount of light in the lens system due to the fine protrusions 13 is taken into account.

[0065] For example, when the optical element 1 (lens) is applied to a camera module using an image sensor, the optical surface is positioned at a back focus of 300 m from the image plane with a lens with an aperture of about F3. 4 and a focal length of about 4 mm. If there is, there is almost no effect on the image from experience! /, The size of the base width W and height H that cause a light intensity decrease of about 2% is about 10 Hm.

[0066] Therefore, the numerical value of the base width W and height H of the cross section of the fine protrusion 13 has an upper limit of 2 μm, which is about 1/5, with a sufficient margin for 10 m. I hope that. That is, when the base width W is smaller than 2 H m and the height H is smaller than 2 H m, there is no possibility that the fine protrusion 13 affects the optical characteristics of the optical element 1. Further, the lower limit needs to be larger than the thickness of the antireflection layer 12 because the antireflection layer 12 needs to be divided.

[0067] The fine protrusion 13 may be formed anywhere as long as it has the shape and size described above, but internal stress generated in the antireflection layer 12 in a high-temperature environment is as efficient as possible. It is desirable to form it so that it can be relaxed well. Therefore, it is desirable to set appropriately using a simulation considering the shape of the optical element 1 (basic resin portion 11) (that is, the lens shape) and the shape of the antireflection layer 12.

[0068] In addition, as described above, the desired cross-sectional dimensions (base width W and height H) vary depending on the conditions (wavelength band to be applied) of using the optical element 1, but even in such a case, the cross-sectional dimensions With respect to the dimensions, when the base width W is smaller than 2 m and the height H is smaller than 2 m, scattering by the fine protrusion 13 does not affect the optical characteristics of the optical element 1 at all.

FIG. 3 is a perspective view schematically showing a modification of the shape of the optical element according to Embodiment 1 of the present invention. FIG.

[0070] As described above, it is sufficiently possible to eliminate the influence of the fine protrusions 13 on the optical characteristics of the optical element 1. However, depending on how the optical element 1 is used, the optical characteristics of the optical element 1 may be deteriorated due to the influence of scattering by the fine protrusions 13. For example, in the above-described camera module, scattering by the fine protrusion 13 affects the low-frequency component of the spatial frequency that the central part of the optical element 1 (the central region 1 li around the optical axis Lax) has, and as a result, There may be a case where the contrast of the image quality is lowered.

[0071] As a countermeasure in such a case, the fine protrusion 13 is arranged in the outer peripheral area l is (the area located outside the central area l li) of the basic resin part 11 away from the optical axis Lax. It is possible to prevent the degradation of the last (the effect of scattering on the low frequency component of the spatial frequency of optical information). Even in this case, it is desirable from the viewpoint of heat resistance to make the central region l li where the fine protrusions 13 are not provided as small as possible. Therefore, it is desirable that the shape and dimension setting of the optical element 1 be determined in consideration of the balance between the improvement in heat resistance and the influence on the optical characteristics.

An optical element according to Embodiment 2 of the present invention will be described with reference to FIG. 4 and FIG.

FIG. 4 is a cross-sectional view showing a structural example of the antireflection layer in the optical element according to Embodiment 2 of the present invention. Note that hatching in the cross section is omitted.

[0074] The antireflection layer 12 according to the present embodiment shown in FIG. 4 has a low refraction made of a material having a refractive index lower than that of the basic resin portion 11 (synthetic resin applied to resin molding). The refractive index layer 12a is used (if it is not necessary to distinguish the low refractive index layer 12a, it is simply referred to as the antireflection layer 12). As the material of the low refractive index layer 12a, magnesium fluoride (MgF) having a refractive index η = 1 · 38 was applied.

[0075] By making the antireflection layer 12 into a single layer structure with the low refractive index layer 12a, deformation (cracking, peeling, etc.) of the antireflection layer 12 in a higher temperature environment can be suppressed. In addition, the single-layer structure prevents internal stress from increasing, and also shortens the process time for film formation, simplifying the manufacturing process of the antireflection layer 12 and reducing manufacturing costs. It becomes.

[0076] In order to deposit magnesium fluoride, a deposition temperature of 200 ° C or higher is required. Therefore, the synthetic resin used for optical element 1 (basic resin portion 11) must withstand high temperatures. Heat-resistant resins such as, for example, silicone resins having an Si-O-Si silica bond, such as silicone resins having alkyl groups or phenyl groups, carbon skeletons and silicone skeletons, and hybridized inorganic / organic hybrid silicone resins It is desirable to apply.

[0077] The film thickness (optical film thickness nd) of the low-refractive index layer 12a is a force S that varies according to the optical characteristics and desired reflection characteristics of the optical element 1, and the material of the antireflection layer 12 as one guideline. It is desirable to set the refractive index n X optical film thickness nd to be 1/4 of the design wavelength.

In optical element 1 according to the present embodiment, base layer 15 is formed between antireflection layer 12 and the surface of basic resin portion 11. The underlayer 15 is not essential because it does not affect the antireflection characteristics. However, the base layer 15 made of an inorganic material having good adhesiveness to the material of the basic resin part 11 and excellent chemical resistance and wear resistance is composed of the antireflection layer 12 and the basic resin part 11. Since it is firmly bonded to improve the adhesiveness, it becomes a factor for suppressing peeling of the antireflection layer 12 due to thermal expansion.

[0079] The underlayer 15 has a refractive index n = l. 49 to 50 whose main component is a key oxide (SiOx (2> x> l)).

1. A thin film structure with a low refractive index material strength of 59 was adopted. This is because the refractive index of the low refractive index material is in the range of the refractive index of the material used as the optical element 1 made of synthetic resin, and the low refractive index material is excellent in chemical resistance and wear resistance. This is because it has good adhesion to the optical element 1 made of synthetic resin and has a small amount of light scattering and light absorption when used as the underlayer 15.

[0080] Further, even if the film thickness of the underlayer 15 is too thick or too thin, the heat resistance, adhesion, wear resistance, and chemical resistance cannot be satisfied, so it is empirically about 200 to 300 nm. Set. This makes it possible to obtain a highly reliable optical element 1 that has excellent wear resistance and chemical resistance and does not cause deterioration of optical characteristics. Note that the height H of the fine protrusions 13 needs to be slightly higher than the thickness in which the base layer 15 and the antireflection layer 12 are laminated.

FIG. 5 is a cross-sectional view showing another structural example of the antireflection layer in the optical element according to Embodiment 2 of the present invention. Note that hatching in the cross section is omitted. [0082] The antireflection layer 12 according to the present embodiment shown in FIG. 5 has a high refraction made of a material having a refractive index higher than that of the basic resin portion 11 (synthetic resin applied to resin molding). The refractive index layer 12b and the low refractive index layer 12c made of a material having a refractive index lower than the refractive index of the basic resin portion 11 are laminated (high refractive index layer 12b and low refractive index layer). If it is not necessary to distinguish 12c, simply use antireflection layer 12).

[0083] With this configuration, the antireflection characteristics can be further improved as compared with the structure example of Fig. 4 (single-layer structure of the antireflection layer 12). It is necessary to have a very low anti-reflection characteristic of less than%! /, And an excellent anti-reflection characteristic as a reflectance! /, And an excellent anti-reflection characteristic applicable in this case can be realized. In addition, the antireflection layer 12 can be further increased in the number of layers depending on the necessary antireflection characteristics shown as a two-layer laminated structure.

[0084] As the high refractive index layer 12b, a high refractive index material mainly composed of titanium oxide (TiO 2), zirconium oxide (ZrO 2), or a mixture thereof can be used.

[0085] The respective film thicknesses (optical film thickness nd) of the high refractive index layer 12b and the low refractive index layer 12c correspond to the optical characteristics and desired reflection characteristics of the optical element 1 as in the case of the low refractive index layer 12a. However, it is desirable to set the refractive index n X optical film thickness nd of the material of the antireflection layer 12 to be 1/4 of the design wavelength.

A transfer mold according to Embodiment 3 of the present invention will be described with reference to FIG.

FIG. 6 is a perspective view schematically showing the shape of the transfer mold according to the third embodiment of the present invention.

The transfer mold 2 according to the present embodiment includes a transfer surface 2s that forms the optical element 1 by transfer (resin molding). The transfer surface 2s includes a basic transfer portion 21 for resin-molding the basic resin portion 11 and a protrusion transfer groove 22 for resin-molding the fine protrusion portion 13. In other words, when the optical element 1 is an aspheric lens (basic resin portion 11), the transfer surface 2s is formed with a shape (basic transfer portion 21) that has a positive-negative relationship with the aspheric shape (basic resin portion 11). It has been done. Similarly, a projection transfer groove 22 having a positive / negative relationship with the fine projection 13 transferred to the optical element 1 is formed. [0089] With this configuration, when the optical element 1 is resin-molded by applying the transfer mold 2, the fine protrusions 13 can be transferred simultaneously with the resin molding of the basic resin part 11, so that both of them can be transferred separately. Compared with this, the production efficiency is improved, and the alignment between the two is not required, and the highly accurate optical element 1 can be manufactured with high productivity. In other words, since the shape (basic transfer portion 21 and protrusion transfer groove 22) for forming the basic resin portion 11 and the fine protrusion portion 13 is formed on the transfer surface 2s, the resin molding process is performed once. Since the optical element 1 including the basic resin portion 11 and the fine protrusions 13 can be manufactured, the highly accurate optical element 1 can be formed at low cost.

[0090] As the mold material of the transfer mold 2, a sintered material such as martensitic stainless steel, oxygen-free copper, or tungsten carbide can be applied.

In general, since the manufacture of molds requires very high precision and high definition technology, the transfer mold 2 according to Embodiment 3 is also required to be manufactured with high precision and high precision. . In addition, since the transfer mold 2 is provided with the fine protrusions 13, it is necessary to manufacture the transfer mold 2 with higher precision and higher precision, and there is a problem that manufacturing is difficult with normal technology. The transfer mold manufacturing method according to the present embodiment provides a method for easily manufacturing the transfer mold 2 by solving such problems.

A transfer mold manufacturing method according to Embodiment 4 of the present invention will be described with reference to FIG.

FIG. 7 is a cross-sectional view schematically showing the shape of the transfer mold in each step of the transfer mold manufacturing method according to Embodiment 4 of the present invention, and FIG. 7 (A) is a mold material. Fig. 7 (B) shows the state of exposing the photoresist for forming the protrusion transfer groove, and Fig. 7 (C) shows the state using the formed resist mask. Fig. 7 (D) shows the completed transfer mold, with the mold material etched and the protrusion transfer groove formed.

First, a mold material for forming the transfer mold 2 (note that the state before completion is also denoted as the transfer mold 2) is prepared (see the left side of FIG. 7 (A)). A basic transfer part 21 is formed on the transfer surface 2s by machining the mold material using an ultra-precision lathe, ultra-precision grinder, etc. (see right of Fig. 7 (A)) (in the basic resin part 11) Basic transfer to form the corresponding basic transfer part 21 Part forming step).

[0095] Photoresist 25 is applied to the transfer surface 2s on which the basic transfer portion 21 is formed, and pre-beta is performed at a temperature of about 100 ° C (see the left side of Fig. 7 (B)). Next, exposure light Lex is irradiated onto the transfer surface 2s to expose (expose) a portion of the photoresist 25 corresponding to the protruding transfer groove 22 to form a photosensitive resist portion 25a that can be removed to form an exposure mask pattern. (Refer to the right of Fig. 7 (B)). The photoresist 25 may be either a positive type or a negative type depending on the exposure method and the shape of the exposure mask pattern corresponding to the protrusion transfer groove 22. In this embodiment, it is described as a positive type.

[0096] After the exposure, the photoresist 25 (exposure mask pattern) is developed to remove the photosensitive resist portion 25a and form a resist mask 25m having an opening 25w corresponding to the protrusion transfer groove 22. (See Figure 7 (C) left). After development, rinse with pure water, etc., and post-beta at a temperature of 100-200 ° C to improve the corrosion resistance of the resist mask 25m (non-photosensitive resist part) (see left of Fig. 7 (C)).

[0097] Resist mask with improved corrosion resistance Transfer mold to etchant Ect using 25m as mask

2 is immersed to etch (pattern) the transfer surface 2s (the surface of the mold material) to form a protrusion transfer groove 22 (see the right in FIG. 7C) (the protrusion corresponding to the fine protrusion 13). A projection transfer groove forming step in which the transfer groove 22 is formed by patterning the surface of the basic transfer portion 21). Etching agent Ect can be applied with a force S that varies depending on the mold material used, and ferric chloride solution can be applied to stainless steel and oxygen-free copper.

[0098] The resist mask 25m is removed with acetone or the like to complete the transfer mold 2 (see FIG. 7D). Thereafter, a release film (such as gold, CrN, TiN, DLC (diamond-like carbon)) is used on the transfer surface 2s in order to improve releasability from the optical element 1 (molded product) molded by resin molding. (Omitted) It is desirable to form a film with a thickness of several nm to several tens of nm! /.

In the transfer mold manufacturing method according to the present embodiment, since the surface shape of the optical element 1 (basic resin portion 11) is a curved surface, even if the corresponding transfer surface 2s is a curved surface, the fine protrusion 13 It is possible to easily form the projection transfer groove 22 for resin molding by patterning, and since the machining is not used for forming the projection transfer groove 22, distortion caused by machining ( (Damage) etc. does not occur and does not affect the shape of the transfer surface 2s. It is possible to easily and inexpensively manufacture a transfer mold 2 of a certain degree.

[0100] <Embodiment 5>

An optical element manufacturing method according to Embodiment 5 of the present invention will be described with reference to FIGS. 8A to 8F.

[0102] The transfer mold 2 for resin-molding the optical element 1 includes an upper mold 20U, a lower mold 20L, an upper trunk mold 23U, and a lower trunk mold 23L. The upper mold 20U and the lower mold 20L include a basic transfer part 21 that transfers the basic resin part 11, and a protrusion transfer groove 22 that transfers the fine protrusions 13. On the outer periphery of the upper mold 20U and the lower mold 20L, an upper trunk mold 23U and a lower trunk mold 23L are arranged corresponding to each other. The upper body mold 23U and the lower body mold 23L define the outer peripheral shape of the basic resin portion 11. The upper trunk mold 23U and the lower trunk mold 23L have gates 27 for injecting synthetic resin during resin molding.

[0104] After the transfer mold 2 is clamped, the synthetic resin Res is injected from the gate 27. There are various methods for injecting synthetic resin, and it is desirable to use injection injection in consideration of the precision and mass productivity of force molding.

[0105] When the synthetic resin Res is thermoplastic, molten synthetic resin Res of about 150 ° C is poured into the transfer mold 2 whose temperature is adjusted to about 80 ° C. The injected synthetic resin Res in the molten state starts to cool and solidify when it comes into contact with the transfer mold 2 to form the basic resin portion 11.

When the synthetic resin Res is thermosetting, the synthetic resin Res in a liquid state of 80 ° C. or less is injected into the transfer mold 2 whose temperature is adjusted to 150 to 200 ° C. The injected liquid synthetic resin Res undergoes a polymerization reaction to form the basic resin portion 11.

[0107] Due to the structure of the transfer mold 2, the fine protrusion 13 is resin-molded simultaneously with the resin molding of the basic resin portion 11, and the optical element 1 in a state where the gate trace 1 lg is connected is formed (the basic resin portion 11). And a resin molding step of resin molding the fine protrusions 13).

FIG. 8C shows a transfer mold applied in the optical element manufacturing method according to Embodiment 5 of the present invention. It is sectional drawing which shows the state which complete | finishes the resin molding and releases an optical element.

The optical element 1 that has finished resin molding with the transfer mold 2 is released from the transfer mold 2.

Thereafter, the gate trace l lg is removed.

[0111] The optical element 1 whose gate outline l lg has been removed and whose external shape has been adjusted is placed in a vapor deposition chamber 30, and an antireflection layer 12 made of an inorganic material is formed by vapor deposition. By forming by vapor deposition, it is possible to control the film thickness of the antireflection layer 12 with high accuracy, and the optical element 1 having high-precision optical characteristics can be obtained.

[0112] deposition chamber one 30 after being evacuated, 1. is maintained in a vacuum state of about OX 10- ⁴ Torr while introducing O gas, magnesium fluoride as described above, titanium oxide, such as oxide zirconium Yuumu The antireflection layer component target 31 is appropriately heated by a resistance heating method or an electron beam heating method to evaporate the antireflection layer component, and the antireflection layer component vapor RV is applied to the optical element 1 to form the antireflection layer 12. Film (evaporation) is performed (an antireflection layer forming step in which the antireflection layer 12 is laminated on the surface of the basic resin portion 11). After the antireflection layer 12 is formed, the vapor deposition chamber 30 is pressurized to atmospheric pressure, opened, and the optical element 1 is taken out.

[0113] When the underlayer 15 is formed between the antireflection layer 12 and the basic resin part 11, the underlayer 15 is formed before the antireflection layer 12 is formed. In other words, a deposition chamber similar to the deposition chamber 30 is applied, and the underlying layer component target such as the above-described silicon oxide is heated to deposit the underlying layer component, and is applied to the optical element 1 to form the underlying layer 15. Film formation (evaporation) is performed (underlayer forming step of laminating underlayer 15 on the surface of basic resin portion 11). The vapor deposition chamber 1 for forming the underlayer 15 and the vapor deposition chamber 30 for forming the antireflection layer 12 are made the same vapor deposition chamber, and the formation of the underlayer 15 and the formation of the antireflection layer 12 are supported by switching the target. It is also possible to make it. Since the formation conditions of the underlayer 15 can be the same as the formation conditions of the antireflection layer 12, a detailed description thereof is omitted.

In this state, the optical element 1 is temporarily completed as a product, but the antireflection layer 12 formed in the antireflection layer forming step is also formed on the surface of the fine protrusion 13 and the fine antireflection layer 12a (see FIG. 8 Refer to E.). The fine antireflection layer 12a adheres to the surface of the fine protrusion 13 In addition, since the slant surface of the fine protrusion 13 is thin and the adhesion is weak, it may be peeled off during use of the optical element 1 to become dust and affect the optical system. Therefore, it is desirable to remove the fine antireflection layer 12a.

FIG. 8E is a cross-sectional view showing a state in which the fine antireflection layer attached to the fine protrusion is removed by the optical element manufacturing method according to Embodiment 5 of the present invention.

[0116] The optical element 1 with the fine antireflection layer 12a attached thereto is placed in the high temperature chamber 40 and heated at a high temperature, whereby the fine antireflection layer 12a attached to the fine protrusions 13 is thinned. Microcrack MC is generated at the place where Next, the optical element 1 is taken out from the high temperature chamber 40 and subjected to ultrasonic cleaning (not shown), so that the fine antireflection layer 12a can be removed.

[0118] By removing the fine antireflection layer 12a, the optical element 1 has the divided antireflection layer 12 on the surface. Further, the antireflection layer 12 is divided by the fine protrusions 13 protruding from the surface of the basic resin part 11.

[0119] According to the optical element manufacturing method according to the present embodiment, the basic resin part 11 and the fine protrusion part 13 are formed at the same time, and the antireflection layer 12 is laminated on the surface of the basic resin part 11. This makes it possible to manufacture optical elements 1 with excellent optical properties with high productivity.

[0120] Since the optical element 1 is manufactured using the transfer mold 2, it is possible to manufacture the optical element 1 in large quantities with high productivity, and to reduce the manufacturing cost and to provide the optical element 1 at low cost. Is possible.

[0121] The present invention can be implemented in various other forms without departing from the spirit or main features thereof. For this reason, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the scope of claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

[0122] Note that this application (or Japanese Patent Application No. 2006-312001 filed in November, 2006, 17-17 Claim priority based on issue. The contents of which are incorporated herein by reference. In addition, the references cited in this specification are specifically incorporated in their entirety by reference thereto.

Industrial applicability

The present invention can be suitably used for an optical element on which an antireflection layer is formed, a transfer mold for transferring such an optical element, a transfer mold manufacturing method for manufacturing the transfer mold, It can be suitably used for an optical element manufacturing method for manufacturing such an optical element.

Claims

The scope of the claims

[1] An optical element made of synthetic resin in which an antireflection layer is formed on the surface of a basic resin portion formed by resin molding,

The optical element, wherein the antireflection layer is formed of an inorganic material and divided.

[2] The optical element according to claim 1,

The optical element is characterized in that the antireflection layer is divided by fine protrusions protruding from the surface of the basic resin part! /.

[3] The optical element according to claim 2,

The optical element characterized in that the shape of the cross section of the fine protrusion in the direction intersecting the length direction of the fine protrusion is any one of a semicircle, a triangle, and a trapezoid.

[4] The optical element according to claim 3,

An optical element characterized in that the bottom width of the cross section of the fine protrusion is smaller than 2 m, and the height of the cross section of the fine protrusion is smaller than 2 m.

[5] The optical element according to claim 2,

The optical element, wherein the fine protrusions are arranged symmetrically with respect to the optical axis of the basic resin part.

[6] The optical element according to claim 5,

The optical element, wherein the fine protrusions are arranged concentrically and radially with respect to the optical axis of the basic resin part.

[7] The optical element according to claim 5,

The optical element, wherein the fine protrusion is disposed in an outer peripheral region of the basic resin portion that is separated from the optical axis of the basic resin portion.

[8] The optical element according to claim 1,

An optical element, wherein an underlayer mainly composed of a silicon oxide is formed between the antireflection layer and the surface of the basic resin portion.

[9] Claim; In the optical element according to any one of claims 8 to 8,

The optical element, wherein the antireflection layer is a low refractive index layer composed of a material having a refractive index lower than that of the basic resin portion.

[10] The optical element according to any one of claims 8 to 8, wherein the antireflection layer is formed of a material having a refractive index lower than that of the basic resin portion. 8. The deviation of! / In claim 1, wherein the refractive index layer and a high refractive index layer made of a material having a refractive index higher than that of the basic resin portion are laminated. The optical element as described in any one.

[11] A transfer mold for resin-molding an optical element including an antireflection layer separated by fine protrusions formed on the surface of a basic resin portion formed by resin molding,

A transfer mold comprising: a basic transfer portion for resin-molding the basic resin portion; and a projection transfer groove for resin-molding the fine protrusion.

[12] A transfer mold manufacturing method for manufacturing a transfer mold for resin-molding an optical element including an antireflection layer separated by fine protrusions formed on the surface of a basic resin part formed by resin molding. ,

A basic transfer portion forming step for forming a basic transfer portion corresponding to the basic resin portion; and a protrusion transfer groove forming step for forming a protrusion transfer groove corresponding to the fine protrusion portion by patterning the surface of the basic transfer portion;

A transfer mold manufacturing method comprising:

[13] An optical element manufacturing method for manufacturing an optical element comprising an antireflection layer separated by fine protrusions formed on the surface of a basic resin part formed by resin molding,

An optical element manufacturing method comprising: a resin molding step of resin-molding the basic resin portion and the fine protrusions; and an antireflection layer laminating step of laminating an antireflection layer on the surface of the basic resin portion.

[14] In the optical element manufacturing method according to claim 13,

The method of manufacturing an optical element, wherein the antireflection layer is laminated by vapor deposition.