阅读说明：本技术 微细凹凸图案薄膜和平视显示器装置 (Fine concave-convex pattern film and flat display device ) 是由 高桥朋宏 夏目崇 唐井贤 于 2020-03-25 设计创作，主要内容包括：本发明提供一种即使在车载用途等中假定的高温使用环境下也可以抑制防反射膜的裂纹发生的微细凹凸图案薄膜。本发明的微细凹凸图案薄膜具备：在至少一部分表面具有微细凹凸图案(P)的基材薄膜(10)、和形成于微细凹凸图案(P)的至少一部分表面上且由无机膜形成的防反射膜(3)。(The invention provides a fine uneven pattern film which can restrain the crack of an anti-reflection film even under the high temperature using environment assumed in the vehicle-mounted application. The fine uneven pattern film of the present invention comprises: the antireflection film comprises a base material film (10) having a fine uneven pattern (P) on at least a part of the surface thereof, and an antireflection film (3) formed on at least a part of the surface of the fine uneven pattern (P) and formed of an inorganic film.)

1. A fine uneven pattern film, comprising:

a base material film having a fine uneven pattern on at least a part of the surface thereof, and

and an antireflection film formed on at least a part of the surface of the fine uneven pattern and made of an inorganic film.

2. The fine concave-convex pattern film according to claim 1,

the fine uneven pattern is formed on a part of the surface of the base material film,

a flat portion on which the fine uneven pattern is not formed is provided around the fine uneven pattern forming region on the surface of the base material film,

the antireflection film is formed on at least a part of the surface of the fine uneven pattern and is not formed on the flat portion.

3. The fine uneven pattern film according to claim 1 or 2, wherein the fine uneven pattern is a pattern in which a plurality of fine convex portions or concave portions are arranged, a distance between centers of the convex portions or concave portions adjacent to each other is 5 to 500 μm, and a height of the convex portions or a depth of the concave portions is 1 to 100 μm.

4. The fine uneven pattern film as set forth in claim 3, wherein the fine uneven pattern is a microlens array pattern in which boundary portions of the convex portions adjacent to each other or boundary portions of the concave portions adjacent to each other are uneven.

5. The fine uneven pattern film according to any one of claims 1 to 4, wherein the antireflection film is a single-layer structure or a laminated structure of a metal oxide film.

6. The fine uneven pattern film according to any one of claims 1 to 5, which is used for a screen of an image display device.

7. A head-up display device comprising the fine uneven pattern film according to claim 6 as an intermediate screen.

Technical Field

The present invention relates to a fine uneven pattern film having an antireflection film on the surface thereof, and a head-up display device using the same.

Background

In recent years, in optical apparatuses used in various fields, plastics have been increasingly used as materials for optical components such as lenses in view of demands for cost reduction, weight reduction, and downsizing. Accordingly, the characteristics required of an antireflection film provided on a plastic optical member have become more and more severe.

Generally, as an antireflection film provided on the surface of an optical member, an inorganic oxide film having a single-layer structure or a laminated structure is used, and the film formation is performed by a vacuum deposition technique or a sputtering technique. The most common configuration of the antireflection film is a configuration in which a high refractive index material and a low refractive index material are alternately stacked. In order to reduce the number of stacked layers, a material having a refractive index is also used in some cases. TiO can be used as the high refractive index material₂、ZrO₂And Nb₂O₅Etc., the low refractive index material may use SiO₂And MgF₂And the like. The medium refractive index material can be Al₂O₃And Y₂O₃And the like.

An antireflection film formed on the surface of a plastic optical member is excellent in antireflection characteristics, and in addition, reliability such as strength, adhesiveness, and heat resistance is important. In particular, plastics are not heat-resistant and tend to cause thermal expansion or thermal deformation, and therefore deterioration in quality due to these properties may be problematic. Since the coefficient of thermal expansion of an antireflection film using an inorganic oxide film formed by a vacuum film formation technique or the like is extremely small as compared with plastic, cracks in the antireflection film tend to easily occur due to thermal expansion deformation of the base plastic. In particular, in applications such as automobiles, even if the antireflection film is used in a high-temperature environment, the antireflection film is required to have higher heat resistance.

As a conventional technique for solving the above-described problems, patent documents 1 and 2 are cited.

Patent document 1 discloses a lens having an antireflection film, in which a crack trigger line formed by fine convex portions or concave portions having a height or depth that does not adversely affect optical performance is formed on a lens surface, and the antireflection film is formed on the lens surface including the crack trigger line (claim 1).

Patent document 2 discloses a method of irradiating a vaporized material for forming an antireflection film with an electron beam in a step of forming an antireflection film on a microlens by vapor deposition (claim 1).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2011-002627

Patent document 2: japanese patent laid-open publication No. 2000-156486

Disclosure of Invention

Problems to be solved by the invention

In the technique described in patent document 1, since the size of the crack trigger line is about 200nm in period and 100nm in height, if the area of the optical member is large, it takes time to form the crack trigger line.

In the technique described in patent document 2, since the vapor deposition material is activated, the adhesion of the antireflection film is improved, the stress remaining in the antireflection film is relaxed, and the occurrence of cracks is suppressed. However, a dedicated facility needs to be prepared, and therefore, the cost increases.

An object of the present invention is to provide: a fine uneven pattern thin film which can suppress the occurrence of cracks in an antireflection film even in a high-temperature use environment assumed for vehicle-mounted applications or the like.

Means for solving the problems

The fine uneven pattern film of the present invention comprises:

a substrate thin film having a fine uneven pattern on at least a part of the surface thereof, and an antireflection film formed on at least a part of the surface of the fine uneven pattern and made of an inorganic film.

The fine uneven pattern may be formed on a part of the surface of the base material film, and a flat portion on which the fine uneven pattern is not formed may be formed around a region of the surface of the base material film where the fine uneven pattern is formed. In this case, the antireflection film is preferably formed on at least a part of the surface of the fine uneven pattern and is not formed on the flat portion.

Preferably, the fine uneven pattern is a pattern in which a plurality of fine convex portions or concave portions are arranged, the distance between centers of the convex portions or concave portions adjacent to each other is 5 to 500 μm, and the height of the convex portions or the depth of the concave portions is 1 to 100 μm.

Further, the fine uneven pattern is preferably a microlens array pattern in which the boundary portions of the convex portions adjacent to each other or the boundary portions of the concave portions adjacent to each other are uneven.

The antireflection film is preferably a single-layer structure or a laminated structure of a metal oxide film.

The fine uneven pattern film of the present invention is suitably used for a screen of an image display device.

The head-up display device of the present invention includes the fine uneven pattern film as an intermediate screen.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, there can be provided: a fine uneven pattern thin film which can suppress the occurrence of cracks in an antireflection film even in a high-temperature use environment assumed for vehicle-mounted applications or the like.

Drawings

Fig. 1 is a schematic cross-sectional view of a fine uneven pattern thin film according to an embodiment of the present invention.

Fig. 2A is a schematic plan view of the fine uneven pattern thin film produced in example 1.

Fig. 2B is a schematic plan view of the fine uneven pattern thin film produced in example 2.

Fig. 2C is a schematic plan view of the fine uneven pattern thin film produced in example 3.

Fig. 3 is a schematic plan view of the fine uneven pattern thin film produced in comparative example 1.

Fig. 4 is an optical micrograph of the fine uneven pattern film produced in comparative example 1 after the heat resistance test.

Detailed Description

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

The fine uneven pattern film of the present invention is a laminated film, and has: the antireflection film includes a base material thin film having a fine uneven pattern on a surface thereof, and an antireflection film formed of an inorganic film on at least a part of the surface of the fine uneven pattern of the base material thin film. Fig. 1 is a schematic cross-sectional view of a fine uneven pattern thin film according to an embodiment of the present invention. In the figure, reference numeral 10 denotes a base film, and reference numeral 3 denotes an antireflection film.

The base film 10 may be any transparent plastic film having a fine uneven pattern on the surface, and may have a single-layer structure or a laminated structure.

In the example shown in fig. 1, the base film 10 is a laminated film in which a resin layer 2 having a fine uneven pattern P on the surface is formed on a flat film body 1.

The base film 10 may be a single-layer film having a fine uneven pattern P on the surface. In this case, reference numeral 1 and reference numeral 2 in fig. 1 are integrated.

The flat film body 1 of the laminated film and the single-layer film having the fine uneven pattern P on the surface are preferably made of materials having a thermal expansion coefficient of 1 × 10^-5～20×10^-5The plastic of/° c is desirably Polycarbonate (PC), polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), or the like.

Examples of the resin layer 2 of the laminated film include a cured resin layer formed of a thermosetting resin or an ultraviolet curable resin.

The fine concave-convex pattern P can form an optical element such as a microlens array, a diffraction element, and a prism.

The fine uneven pattern P is a pattern in which a plurality of fine convex portions or concave portions are arranged. The distance between the centers of the adjacent projections or recesses is not particularly limited, but is preferably 5 to 500 μm, for example. The height of the projection and the depth of the recess are not particularly limited, but are preferably 1 to 100 μm, for example.

When the fine uneven pattern film of the present invention is used for an intermediate screen of an image display device such as a head-up display, the fine uneven pattern P is desirably a microlens array pattern in which the distance between the centers of adjacent convex portions or concave portions is 10 to 200 μm, and the height of the convex portions or the depth of the concave portions is 5 to 50 μm.

The fine uneven pattern P is preferably a microlens array pattern in which the boundary portions of the convex portions adjacent to each other or the boundary portions of the concave portions adjacent to each other are uneven.

The antireflection film 3 is an inorganic film having a single-layer structure or a laminated structure formed of a metal oxide.

The antireflection film 3 may be made of 1 material having a refractive index lower than that of the fine uneven pattern P. When the antireflection film 3 is formed of a plurality of materials, it is preferable to stack a material having a higher refractive index than the fine uneven pattern P (high refractive index material) and a material having a lower refractive index than the fine uneven pattern P (low refractive index material), and it is preferable to alternately stack a high refractive index material and a low refractive index material. In order to reduce the number of stacked layers, a material having a refractive index is sometimes used.

TiO can be used as the high refractive index material₂、ZrO₂And NB₂O₅Etc., the low refractive index material may use SiO₂And MgF₂And the like. The medium refractive index material can be Al₂O₃And Y₂O₃And the like.

The inorganic film having a single-layer structure or a laminated structure can be produced by a known technique such as a vacuum evaporation technique or a sputtering technique.

The region in which the fine uneven pattern P is provided (also referred to as "fine uneven pattern formation region") may be the entire surface of the base material film 10 or may be a part of the surface of the base material film 10. The antireflection film 3 may be formed on all or a part of the surface of the fine uneven pattern P.

When the fine uneven pattern P is formed on a part of the surface of the base material film 10 and a flat portion where the fine uneven pattern is not formed exists around the fine uneven pattern forming region on the surface of the base material film 10, the antireflection film 3 cannot be formed on the flat portion. For example, as in example 3 (fig. 2C) described later, the antireflection film is not formed on the flat portion, but as in comparative example 1 (fig. 3) described later, the antireflection film is not formed on the flat portion. In fig. 2C and 3, reference numeral 4 denotes a fine uneven pattern formation region, reference numeral 5 denotes an antireflection film formation region, and reference numeral 6 denotes a flat portion.

When the antireflection film 3 is provided on the flat portion of the base film 10, the following problems occur. When the fine uneven pattern film is exposed to a high temperature environment, the base material film 10 thermally expands in the in-plane direction. In this case, the antireflection film 3 formed on the flat portion of the base film 10 is thermally expanded in the same manner, but the antireflection film 3 formed of an inorganic film generally has a smaller linear expansion coefficient than the base film 10, and therefore cannot follow the thermal expansion of the base film 10, and there is a possibility that cracks are generated in the antireflection film 3 formed on the flat portion of the base film 10. Further, the crack may be propagated to the antireflection film 3 formed on the fine uneven pattern P with the crack as a starting point. For this reason, the antireflection film 3 is not formed on the flat portion of the base film 10.

When the antireflection film 3 is formed only on the fine uneven pattern P, the cracking of the antireflection film 3 can be effectively suppressed even in a high-temperature use environment assumed for in-vehicle use or the like.

The reason why the starting point of the crack is not formed in the antireflection film 3 formed on the fine uneven pattern P is not clear at present, but is considered as follows.

The deformation on the fine uneven surface becomes three-dimensional deformation in the thickness direction rather than two-dimensional deformation only in the in-plane direction, and therefore, as a result, the amount of deformation becomes small.

Since the fine uneven surface has a three-dimensionally complicated shape, when the fine uneven pattern thin film is exposed to a high-temperature environment, not only tensile stress but also bending stress or compressive stress occurs, and thus stress as large as crack generation is less likely to occur.

In order to facilitate the formation of the antireflection film 3, when the antireflection film 3 must be formed on the flat portion of the base film 10, the flat portion of the base film 10 may be removed by performing additional processing such as outline processing after the formation of the antireflection film 3.

In the case where the flat portion cannot be removed, a pseudo fine uneven pattern (for example, a fine uneven pattern having optical characteristics different from the required characteristics of the product) may be formed on the flat portion, and the antireflection film 3 may be formed thereon.

As described above, according to the present invention, there can be provided: a fine uneven pattern thin film which can suppress the occurrence of cracks in an antireflection film even in a high-temperature use environment assumed for vehicle-mounted applications or the like.

The use of the fine uneven pattern film of the present invention is not particularly limited. The fine uneven pattern film of the present invention is suitably used for a screen of an image display device such as a head-up display device, for example. According to the present invention, with the performance required as the screen of the image display apparatus, it is possible to provide: a fine uneven pattern thin film which can suppress the occurrence of cracks in an antireflection film even in a high-temperature use environment assumed for vehicle-mounted applications or the like.

According to the present invention, there can be provided: the head-up display device comprises the fine uneven pattern film of the present invention as an intermediate screen and can suppress the occurrence of cracks in the intermediate screen even in a high-temperature use environment assumed in an in-vehicle application or the like.

The present invention is not limited to the above-described embodiments, and design changes can be made as appropriate without departing from the spirit of the present invention.

Examples

The present invention will be described in further detail below with reference to examples, but the present invention is not limited to the following examples.

Examples 1 to 3 and comparative example 1

In each of examples 1 to 3 and comparative example 1, a fine uneven pattern thin film was produced as follows. In these examples, the conditions of the range of the fine uneven pattern formation region and the range of the antireflection film formation region are changed, and the other conditions are set as common conditions.

(production of base film)

A commercially available Polycarbonate (PC) film having a thickness of 300 μm was prepared, and the film was cut to obtain a film body having a length of 110mm × a width of 47 mm. A commercially available acrylic ultraviolet-curable resin was used to form a resin layer having a microlens array pattern having a period of 30 μm and arranged in a square lattice on the surface as a fine uneven pattern on the film body, thereby obtaining a base film. When the longitudinal direction (110mm direction) of the film body is defined as the X direction and the width direction (47mm direction) is defined as the Y direction, each microlens is an image-deforming lens having a spherical shape with a curvature radius of 73 μm in the X direction and a spherical shape with a curvature radius of 47 μm in the Y direction.

(formation of antireflection film)

By vapor deposition, SiO₂And TiO₂Alternately formed on the surface of the microlens array pattern to form an antireflection film having a 5-layer structure. The material and film thickness of each layer are as follows. Note that the layer closest to the microlens array pattern is referred to as the 1 st layer.

Layer 1: SiO 2₂10.9nm thick,

Layer 2: TiO 2₂13.6nm thick,

Layer 3: SiO 2₂34.3nm thick,

Layer 4: TiO 2₂113.8nm thick,

Layer 5: SiO 2₂87.0nm thick.

(Heat resistance test)

The fine uneven pattern film obtained after the formation of the antireflection film was put into an oven at 125 ℃, taken out after the lapse of 200 hours, and subjected to appearance observation using a microscope made by Keyence as an optical microscope. In comparative example 1, after the appearance observation, the fine uneven pattern film was again put into an oven at 125 ℃, taken out after the lapse of 200 hours, and subjected to appearance observation again using a microscope made by Keyence.

The temperature of 125 ℃ is a temperature condition severer than the temperature of a high-temperature use environment assumed in an in-vehicle application or the like.

< example 1 >

In example 1, a microlens array pattern as a fine uneven pattern was formed on the entire surface of a base film, and an antireflection film was formed on the entire surface thereof. Fig. 2A is a schematic plan view of the fine uneven pattern thin film produced in this example. In the figure, reference numeral 4 denotes a region for forming a fine uneven pattern, and reference numeral 5 denotes a region for forming an antireflection film. In this example, the entire surface of the base film, the region where the fine uneven pattern is formed, and the region where the antireflection film is formed are completely aligned with each other at the peripheral edge portion of the base film without a flat portion.

In this example, no crack was generated in the antireflection film even after the fine uneven pattern film was left at a temperature of 125 ℃ for 200 hours.

< example 2 >

In example 2, a microlens array pattern as a fine uneven pattern was formed on the entire surface of a base film, and an antireflection film was formed in a region 3mm inside from the outer peripheral end of the base film. In this example, the entire surface of the base film is completely aligned with the fine uneven pattern forming region without a flat portion at the peripheral edge of the base film, and the antireflection film is formed to have a size smaller than that of the flat portion, and the antireflection film is not formed at the peripheral edge of the fine uneven pattern. Fig. 2B is a schematic plan view of the fine uneven pattern thin film produced in this example. In the figure, reference numeral 4 denotes a region for forming a fine uneven pattern, and reference numeral 5 denotes a region for forming an antireflection film.

In this example, no crack was generated in the antireflection film even after the fine uneven pattern film was left at a temperature of 125 ℃ for 200 hours.

< example 3 >

In example 3, a flat portion having a width of 6mm was left on the peripheral edge portion of the surface of the base film, and a microlens array pattern was formed in a region inside of the flat portion. An antireflection film was formed in a region 10mm inside from the outer peripheral end of the material film. In this example, a flat portion is left in the peripheral edge portion of the base material film, and a fine uneven pattern is formed in a size smaller than that of the base material film, an antireflection film is formed in a size smaller than that of the fine uneven pattern, and the antireflection film is not formed in the peripheral edge portion of the fine uneven pattern. Fig. 2C is a schematic plan view of the fine uneven pattern thin film produced in this example. In the figure, reference numeral 4 denotes a fine uneven pattern formation region, reference numeral 5 denotes an antireflection film formation region, and reference numeral 6 denotes a flat portion.

In this example, no crack was generated in the antireflection film even after the fine uneven pattern film was left at a temperature of 125 ℃ for 200 hours.

< comparative example 1 >

A fine uneven pattern film was produced in the same manner as in example 3, except that an antireflection film was formed in a region 3mm inside from the outer peripheral end of the base film in comparative example 1. In this example, a flat portion is left on the peripheral edge portion of the base material film, a fine uneven pattern is formed in a size smaller than the base material film, an antireflection film is formed in a size smaller than the base material film and larger than the fine uneven pattern, and the antireflection film is formed on the fine uneven pattern and the flat portion. Fig. 3 is a schematic plan view of the fine uneven pattern thin film produced in this example. In the figure, reference numeral 4 denotes a fine uneven pattern formation region, reference numeral 5 denotes an antireflection film formation region, and reference numeral 6 denotes a flat portion.

In this example, after the fine uneven pattern film was left at a temperature of 125 ℃ for 200 hours, cracks were generated in the antireflection film formed on the flat portion of the base film. Further, when the fine uneven pattern film is left to stand at a temperature of 125 ℃ for 200 hours, cracks generated in the antireflection film on the flat portion propagate to the antireflection film on the microlens array.

Fig. 4 shows an optical micrograph of the sample after the heat resistance test for a total of 400 hours. In the figure, reference numeral 7 denotes a flat portion of a resin layer prepared using an ultraviolet curable resin, reference numeral 8 denotes a microlens array pattern, reference numeral 9 denotes a crack generated in the flat portion, and reference numeral 10 denotes a crack generated in a formation region of a microlens. The photograph shown in fig. 4 shows how cracks propagate from the antireflection film on the flat portion to the antireflection film on the microlens array pattern.

The present application claims priority based on Japanese application Japanese application Special application No. 2019-060207, applied on 3/27/2019, the entire disclosure of which is incorporated herein by reference.

Description of the reference numerals

1 film body, 2 resin layer, 3 antireflection film, 4 fine uneven pattern formation region, 5 antireflection film formation region, 6 flat portion, 10 base film, P fine uneven pattern.