JP2023007511A - Optical member and its manufacturing method - Google Patents

Abstract

To provide an optical member that has salt water resistance and a photocatalyst effect and has a reflection prevention film for reducing spectral reflectance in a visible light region, and to provide its manufacturing method.SOLUTION: An optical member has a dielectric multilayer film on a board, the dielectric multilayer film has at least a low refractive index layer L(1), a high refractive index layer H(2), and a reflection prevention layer AR, a refractive index to helium d rays of the low refractive index layer L(1) is less than 1.7, a refractive index to the helium d rays of the high refractive index layer H(2) is equal to or more than 1.7, at least the low refractive index layer L(1) contains yttrium fluoride (YF3), the high refractive index layer H(2) contains a metal oxide having photocatalyst properties, and the thickness of the high refractive index layer H(2) is within a range of 200 to 550 nm.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to an optical member and a method for producing the same, and more particularly to an optical member having an antireflection film having salt water resistance and a photocatalytic effect and having a reduced spectral reflectance in the visible light region, and a method for producing the same.

2. Description of the Related Art A camera is mounted on a vehicle for driving assistance of the vehicle. More specifically, a camera that captures the rear and sides of the vehicle is mounted on the car body, and the image captured by the camera is displayed in a position where the driver can see it, thereby reducing blind spots and improving the driving experience. This assistance contributes to safe driving.

By the way, in-vehicle cameras are often installed outside the vehicle, and there are strict requirements for guaranteeing the environmental resistance of the lenses used. For example, in a salt water spray test on a lens, when SiO ₂ or MgF ₂ , which is a component of the antireflection film on the lens surface, dissolves in salt water and changes the spectral reflectance, it causes the generation of ghost and flare.

Further, in Patent Document 1, there is a need for an antireflection film having self-cleaning properties (photocatalytic effect) for optical lenses used outdoors. It is disclosed that _two membranes are required. However, in a TiO ₂ film in which a plurality of TiO ₂ films are formed in a thick film, the average spectral reflectance in the visible light region exceeds 10%, and the spectral reflectance is not sufficiently reduced.

Therefore, in the salt spray test, the lens surface exhibited no change in spectral reflectance due to dissolution and exfoliation of the main component, no ghost or flare, and an optical member having self-cleaning properties and reduced spectral reflectance. Emergence is awaited.

Japanese Patent Application Laid-Open No. 2003-287601

The present invention has been made in view of the above problems and circumstances, and the problem to be solved is an optical member having an antireflection film having salt water resistance and a photocatalytic effect and having a reduced spectral reflectance in the visible light range; It is to provide a manufacturing method thereof.

In order to solve the above problems, the inventors of the present invention, in the process of studying the causes of the above problems, have found an optical member having a dielectric multilayer film on a substrate, the dielectric multilayer film being the top layer of the dielectric multilayer film. The refractive index layer contains a specific compound, the high refractive index layer immediately below the top layer contains a photocatalytic metal oxide, and the thickness of the high refractive index layer is within a specific range. It has been found that an optical member having an antireflection film having salt water resistance and a photocatalytic effect and having a reduced spectral reflectance in the visible light region and a method for producing the same can be obtained.

That is, the above problems related to the present invention are solved by the following means.

1. An optical member having a dielectric multilayer film on a substrate,
The dielectric multilayer film has a low refractive index layer L (1), a high refractive index layer H (2), and an antireflection layer AR from at least the surface,
The low refractive index layer L (1) has a refractive index of less than 1.7 for the helium d-line, and the high refractive index layer H (2) has a refractive index of 1.7 or more for the helium d-line,
At least the low refractive index layer L(1) contains yttrium fluoride (YF ₃ ),
The high refractive index layer H(2) contains a photocatalytic metal oxide, and the thickness of the high refractive index layer H(2) is in the range of 200 to 550 nm. optical components.
2. An optical member having a dielectric multilayer film on a substrate,
The dielectric multilayer film includes, from at least the surface, a low refractive index layer L(1), a high refractive index layer H(2), a low refractive index layer L(3), a high refractive index layer H(4), and an antireflection layer. is the configuration of the AR,
The low refractive index layers L(1) and L(3) have a refractive index of less than 1.7 for the helium d-line, and the high refractive index layers H(2) and H(4) have a refractive index for the helium d-line. ratio is 1.7 or more,
The low refractive index layers L(1) and L(3) contain yttrium fluoride (YF ₃ ),
The high refractive index layers H(2) and H(4) contain photocatalytic metal oxides, and the sum of the thicknesses of the high refractive index layers H(2) and H(4) is 200. An optical member characterized in that it is within the range of ~550 nm.
3. 3. The optical member according to item 1 or 2, wherein the metal oxide is titanium oxide (TiO ₂ ).
4. 4. The optical member according to any one of items 1 to 3, wherein the thickness of the low refractive index layer L(1) is in the range of 60 to 120 nm.
5. 5. The optical member according to any one of items 2 to 4, wherein the thickness of the low refractive index layer L(3) is in the range of 3 to 23 nm.
6. 6. The optical member according to any one of items 1 to 5, wherein the antireflection layer AR has a layer containing at least silicon oxide ( _SiO2 ).
7. 7. The method according to any one of items 1 to 6, wherein the average spectral reflectance for light incident from the normal direction is 1.5% or less in the light wavelength range of 420 to 680 nm. optical member.
8. A method for manufacturing an optical member according to any one of items 1 to 7, comprising:
A method for producing an optical member, wherein the layer containing TiO ₂ and the layer containing SiO ₂ are formed using an ion-assisted deposition method.

According to the above means of the present invention, it is possible to provide an optical member having an antireflection film having saltwater resistance, a photocatalytic effect, and reduced spectral reflectance in the visible light region, and a method for producing the same.

The expression mechanism or action mechanism of the effect of the present invention is as follows.

An optical member of the present invention is an optical member having a plurality of antireflection layers on a substrate, and is characterized by containing yttrium fluoride (YF ₃ ), which is a low refractive index material, in the uppermost layer. .

The _{SiO2 -} containing layer that forms the top layer of a conventional dielectric multilayer film has a problem with salt water resistance. 20 nm, the spectral reflectance of the sample at a light wavelength of 550 nm changes significantly from 0.5% to 3.0%. Due to such changes, for example, when the uppermost layer of the antireflection layer (dielectric multilayer film) on the lens is dissolved and peeled off by the external environment (salt water), flare and ghost are generated, and the performance deteriorates from the initial manufacturing performance. it is conceivable that.

This is because, in the salt spray test of the SiO ₂ -containing layer, the pH of the salt water at 25° C. is about 7 (weakly alkaline), so the Si—O bonds are easily broken, and the containing layer gradually dissolves in the salt water and peels off. It is presumed that Therefore, by containing yttrium as an element whose activity of oxides and hydroxides is larger than that of ions in the pH range, and further containing fluorine atoms, the water contact angle on the surface is large and water repellency is expressed. Therefore, yttrium fluoride (YF ₃ ), which is a metal fluoride, is calculated to be about 1.3 from the solubility and density in salt water when the layer thickness is the same as that of the SiO ₂ -containing layer in the salt spray test. It is presumed to have excellent resistance to salt water (solubility).

In addition, yttrium fluoride (YF ₃ ) has a filling factor in the film when formed, which is about the same as that of SiO ₂ , and therefore has excellent photocatalyst permeability from the lower layer.
As another low refractive index material, MgF ₂ (refractive index 1.385) has a high filling rate in the film, so that the photocatalyst permeability from the lower layer is poor. Also, Al ₂ O ₃ (refractive index 1.620) is similarly inferior in salt water resistance and photocatalyst permeability from the lower layer. against them. YF ₃ is considered to be an excellent material that satisfies the properties required for the top layer in terms of saltwater resistance, photocatalytic permeability, and refractive index (reduction of spectral reflectance).

In the present invention, the high refractive index layer H(2) or the high refractive index layers H(2) and H(4) contain a photocatalytic metal oxide, and the high refractive index layer H(2) ), or the total thickness of the high refractive index layers H(2) and H(4) is in the range of 200 to 550 nm.

It is known that if the optical film thickness (refractive index nd/wavelength λ) is 1/4 (0.25) or 1/2 (0.5), interference occurs and the antireflection film becomes an antireflection film. ing.

Therefore, if the layer constituting the antireflection film has a layer thickness greater than 1/2λ, interference occurs in the reflected light, and the spectral reflection characteristic deteriorates due to poor phase matching.

On the other hand, it is effective to increase the thickness of the layer containing the metal oxide having photocatalytic properties in order to enhance the photocatalytic properties, but if the layer is too thick, the spectral reflectance cannot be reduced. Therefore, in order to reduce the spectral reflectance and effectively exhibit photocatalytic properties, the high refractive index layer H(2) containing a metal oxide having photocatalytic properties, or the high refractive index layer H(2) The sum of the thicknesses of H(4) is preferably within the range of 200 to 550 nm, and the sum of the thicknesses of the high refractive index layers H(2) and H(4) is preferably within the range of 200 to 550 nm. As noted, the latter method of dividing into two layers to reduce the thickness of each layer is more effective.

Schematic diagram showing the configuration of the optical member of the present invention Schematic diagram showing an example of an IAD vapor deposition apparatus Graph of measured spectral reflectance of an optical member sample Graph of measured spectral reflectance of an optical member sample Graph of measured spectral reflectance of an optical member sample Graph of measured spectral reflectance of an optical member sample Schematic diagram showing the photocatalytic effect evaluation method

The optical member of the present invention is an optical member having a dielectric multilayer film on a substrate, wherein the dielectric multilayer film comprises a low refractive index layer L (1) and a high refractive index layer H (2) from at least the surface. , and an antireflection layer AR, wherein the low refractive index layer L (1) has a refractive index of less than 1.7 for the helium d-line, and the high refractive index layer H (2) the helium d-line is 1.7 or more, at least the low refractive index layer L (1) contains yttrium fluoride (YF ₃ ), and the high refractive index layer H (2) is a photocatalytic metal The high refractive index layer H(2) contains an oxide, and the thickness of the high refractive index layer H(2) is in the range of 200 to 550 nm. This feature is a technical feature common to or corresponding to the following embodiments.

Further, the optical member of the present invention is an optical member having a dielectric multilayer film on a substrate, wherein the dielectric multilayer film comprises a low refractive index layer L (1) and a high refractive index layer H (from at least the surface thereof). 2), a structure of a refractive index layer L (3), a high refractive index layer H (4), and an antireflection layer AR; is less than 1.7, the high refractive index layers H(2) and H(4) have a refractive index of 1.7 or more for the helium d-line, and the low refractive index layers L(1) and L (3) contains yttrium fluoride (YF ₃ ), the high refractive index layers H(2) and H(4) contain metal oxides having photocatalytic properties, and the high refractive index layers It is characterized in that the sum of the thicknesses of H(2) and H(4) is in the range of 200-550 nm.

As an embodiment of the present invention, from the viewpoint of exhibiting the effects of the present invention, the metal oxide is TiO ₂ from the viewpoint of having high photocatalytic properties and imparting excellent self-cleaning properties to optical members. This is a preferred embodiment.

The thickness of the low refractive index layer L(1) is preferably in the range of 60 to 120 nm from the viewpoint of reducing salt water resistance and spectral transmittance.

It is preferable that the thickness of the low refractive index layer L (3) is in the range of 3 to 23 nm from the viewpoint of further improving salt water resistance by providing two YF ₃ -containing layers as intermediate layers. be.

From the viewpoint of antireflection properties, it is preferable that the low refractive index material has a layer containing at least SiO ₂ as an antireflection film inside the optical member.

Regarding the spectral reflectance of the optical member of the present invention, the average spectral reflectance for light incident from the normal direction in the light wavelength range of 420 to 680 nm is preferably 1.5% or less, and more preferably 0.5% on average. The following is more preferable from the viewpoint of improving the visibility of the image captured by the vehicle-mounted lens.

In the optical member manufacturing method for manufacturing the optical member of the present invention, the layer containing TiO ₂ and the layer containing SiO ₂ are formed by an ion-assisted deposition method (IAD vacuum deposition method or simply called IAD method). ) is a preferable method for producing an optical member from the viewpoint of forming a denser film and further improving salt water resistance.

DETAILED DESCRIPTION OF THE INVENTION The present invention, its constituent elements, and embodiments and modes for carrying out the present invention will be described in detail below. In the present application, "-" is used to mean that the numerical values before and after it are included as the lower limit and the upper limit.

<<Outline of the optical member of the present invention>>
The optical member of the present invention is an optical member having a dielectric multilayer film on a substrate, wherein the dielectric multilayer film comprises a low refractive index layer L (1) and a high refractive index layer H (2) from at least the surface. , and an antireflection layer AR, wherein the low refractive index layer L (1) has a refractive index of less than 1.7 for the helium d-line, and the high refractive index layer H (2) the helium d-line is 1.7 or more, at least the low refractive index layer L (1) contains yttrium fluoride (hereinafter sometimes referred to as YF ₃ ), and the high refractive index layer H ( 2) contains a photocatalytic metal oxide, and the thickness of the high refractive index layer H(2) is in the range of 200 to 550 nm.

Further, the optical member of the present invention is an optical member having a dielectric multilayer film on a substrate, wherein the dielectric multilayer film comprises a low refractive index layer L (1) and a high refractive index layer H (from at least the surface thereof). 2), a structure of a refractive index layer L (3), a high refractive index layer H (4), and an antireflection layer AR; is less than 1.7, the high refractive index layers H(2) and H(4) have a refractive index of 1.7 or more for the helium d-line, and the low refractive index layers L(1) and L (3) contains yttrium fluoride (YF ₃ ), the high refractive index layers H(2) and H(4) contain metal oxides having photocatalytic properties, and the high refractive index layers It is characterized in that the sum of the thicknesses of H(2) and H(4) is in the range of 200-550 nm.
In particular, the sum of the thicknesses of the high refractive index layers H(2) and H(4) is preferably within the range of 200 to 290 nm from the viewpoint of developing photocatalytic properties and reducing spectral reflectance.

FIG. 1 is a schematic diagram showing the configuration of the optical member of the present invention.

FIG. 1(a) is a schematic diagram showing an optical member 100 according to the first embodiment.

The dielectric multilayer film 115 having an antireflection function includes, for example, high refractive index layers 103 and 105 having a higher refractive index than the glass substrate 101 constituting the lens, and a lower refractive index layer than the high refractive index layer. An antireflection layer AR107 composed of low refractive index layers 102, 104, and 106 having a refractive index, and a high refractive index layer H(2) 108 and YF3 _, which is a layer containing a metal oxide having photocatalytic properties. It has a low refractive index layer L(1) which is the uppermost layer. The antireflection layer AR according to the present invention preferably has a multilayer structure in which the high refractive index layers and the low refractive index layers are alternately laminated. The optical member of the present invention preferably has an average spectral reflectance of 1.5% or less for light incident from the normal direction in the light wavelength range of 420 to 680 nm. This is preferable from the viewpoint of improving the visibility of the imaged image. Furthermore, the average spectral reflectance is more preferably 0.5% or less. The average spectral reflectance is, for example, in a light wavelength range of 380 to 780 nm, using an Olympus microspectrometer USPM-RU III, to measure the spectral reflectance for light incident from the normal direction, The average spectral reflectance can be obtained by appropriately extracting and averaging the spectral reflectance values in the light wavelength range of 420 to 680 nm, which is the visible light region.

The top layer 109 according to the present invention is a metal fluoride layer containing _YF3 as its main component. A refractive index of less than 1.7 for the helium d-line (optical wavelength of 587.56 nm) of the uppermost layer is a preferable refractive index range from the viewpoint of reducing the spectral reflectance.

The layer immediately below the uppermost layer according to the present invention refers to the high refractive index layer H(2) 108, which is a layer containing a photocatalytic metal oxide in FIG. 1(a). The refractive index of the high refractive index layer H(2) 108 with respect to the helium d-line (optical wavelength 587.56 nm) is preferably 1.7 or more from the viewpoint of reducing the spectral reflectance. .

FIG. 1B is a schematic diagram showing an optical member 100 according to the second embodiment.

The dielectric multilayer film 115 having an antireflection function includes, for example, high refractive index layers 103 and 105 having a higher refractive index than the glass substrate 101 constituting the lens, and a lower refractive index layer than the high refractive index layer. An antireflection layer AR107 composed of low refractive index layers 102, 104, and 106 having a refractive index, and high refractive index layers H(2) 108 and H(4), which are layers containing metal oxides having photocatalytic properties. 110, a low refractive index layer L(1) as a top layer containing YF ₃ , and L(3) 111 as an intermediate layer. The low refractive index layer L(3) may be hereinafter referred to as an "intermediate layer".

As described above, if the layer constituting the antireflection film has a layer thickness much larger than 1/2λ, interference occurs in the reflected light, and the phases do not match well, thereby degrading the spectral reflection characteristics. On the other hand, it is effective to increase the thickness of the layer containing the metal oxide having photocatalytic properties in order to enhance the photocatalytic properties, but if the thickness is increased, the spectral reflectance cannot be reduced. Therefore, in order to reduce the spectral reflectance and effectively exhibit photocatalytic properties, the high refractive index layer H(2) containing a metal oxide having photocatalytic properties and It is effective to divide into two layers like H(4) and design so that the total layer thickness is within the range of 200 to 550 nm.

In the optical member of the present invention shown in FIG. 1, a low refractive index layer, a high refractive index layer, an uppermost layer 109 according to the present invention, and a layer directly thereunder 108 are laminated on a substrate 101 to form a dielectric multilayer film. However, on both sides of the substrate 101, the top layer according to the present invention and the layer directly thereunder may be formed. That is, although it is a preferred embodiment that the top layer and the layer immediately below it according to the present invention are on the side exposed to the external environment, they are not on the exposed side, for example, the inner side opposite to the exposed side Also, in order to prevent the influence of the internal environment, the uppermost layer according to the present invention and the layer immediately below it may be formed. In addition to lenses, the optical member of the present invention can be applied to optical members such as antireflection members and heat shield members.

[1] Structure and manufacturing method of dielectric multilayer film [1.1] Structure and manufacturing method of low refractive index layers L(1) and L(3) Low refractive index layers L(1) and L according to the present invention (3) is a layer containing YF ₃ as the main component, and the “main component” means that YF ₃ contained in the layer is preferably 90% by mass or more, and is 95% by mass or more. More preferably, the content is particularly preferably 98% by mass or more.

The refractive index of the low refractive index layer L(1) for light having a wavelength of 587.56 nm (d-line) is preferably less than 1.7 from the viewpoint of reducing the spectral reflectance. A more preferable refractive index is in the range of 1.45 to 1.55.
The thickness of the low refractive index layer L (1) is preferably in the range of 60 to 120 nm from the viewpoint of salt water resistance and reduction in spectral reflectance. The thickness of (3) is preferably in the range of 3 to 23 nm.

In order to ensure high productivity, the preferred method for forming the low refractive index layers L(1) and L(3) of the present invention includes a vacuum deposition method in the vapor deposition system, and a sputtering method and a magnetron sputtering method in the sputtering system. Utilization is preferable. Note that it is preferable not to use the IAD method or the like for forming the metal fluoride film because the metal fluoride is decomposed by ion irradiation.

When a vacuum deposition method is employed as film forming conditions, the degree of pressure reduction in the chamber is usually 1×10 ⁻⁴ to 1×10 ⁻¹ Pa, preferably 1×10 ⁻³ to 1×10 ⁻² Pa. Then, the film formation rate is in the range of 1 to 10 Å / sec, specifically, for example, using Synchron BES-1300, heating temperature: 340 ° C., starting vacuum degree 1.33 × 10 ^-3 Pa and growth It is preferable to form the film at a film rate of 7 Å/sec. Also, the SiO ₂ -containing layer and the MgF ₂ -containing layer are formed in the same manner as above even when they are formed without using the IAD method.

[1.2] Structure and Manufacturing Method of Antireflection Layer AR and High Refractive Index Layers H(2) and H[4] It has a high refractive index layer having a refractive index and a low refractive index layer having a lower refractive index than the high refractive index layer. It is preferable to have a multilayer structure in which these high refractive index layers and low refractive index layers are alternately laminated. Although the number of layers is not particularly limited, it is preferably 12 layers or less from the viewpoint of obtaining an antireflection layer while maintaining high productivity. That is, the number of layers depends on the required optical performance, but by laminating about 3 to 8 layers, the reflectance of the entire visible light region can be reduced, and the upper limit is 12 layers or less. This is preferable in that it can prevent peeling of the film due to an increase in the stress of the film.

The refractive index of the high refractive index layer for a light wavelength of 587.56 nm is within the range of 1.9 to 2.45, and the refractive index of the low refractive index layer for a light wavelength of 587.56 nm is 1.3 to 1.5. is preferably within the range of

Materials used for the antireflection layer AR of the dielectric multilayer film (high refractive index layer, low refractive index layer) according to the present invention are preferably Ti, Ta, Nb, Zr, Ce, La, Al, Oxides such as Si and Hf, or a combination of oxide compounds and _MgF2 are suitable. Also, by stacking a plurality of layers of different dielectric materials, it is possible to add a function of reducing the reflectance of the entire visible light range.

The low refractive index layer is made of a material having a lower refractive index than the substrate, and in the present invention, it is preferably SiO ₂ or a mixture of SiO ₂ and Al ₂ O ₃ . In particular, a layer containing SiO ₂ is preferable from the viewpoint of reducing the spectral reflectance.

The high refractive index layer is made of a material having a higher refractive index than the substrate. and a mixture of oxides of Ti and the like. In the present invention, Ta ₂ O ₅ and TiO ₂ are preferred, and Ta ₂ O ₅ is more preferred.

In the optical member of the present invention, a layer containing TiO ₂ is used as a photocatalyst layer having a self-cleaning function in the high refractive index layer H(2) or the high refractive index layers H(2) and H(4). use. The self-cleaning function of TiO ₂ refers to the effect of decomposing organic matter by a photocatalyst. This is because when TiO ₂ is irradiated with ultraviolet light, OH radicals are generated after electrons are emitted, and organic substances are decomposed by the strong oxidizing power of the OH radicals. By adding the TiO ₂ -containing layer to the optical member of the present invention, it is possible to prevent organic matter adhering to the optical member from contaminating the optical system. In this case, the upper YF ₃ -containing layer preferably has a slightly rough film quality because OH radicals can easily move and the antifouling property of the surface of the optical member can be improved.

As described above, the high refractive index layer H(2) or the sum of the thicknesses of the high refractive index layers H(2) and H(4) is preferably within the range of 200 to 550 nm. The latter method is to divide into two layers to reduce the metal oxide content per layer such that the sum of the thicknesses of the layers H(2) and H(4) is within the range of 200-550 nm. more effective.
In particular, the sum of the thicknesses of the high refractive index layers H(2) and H(4) is preferably within the range of 200 to 290 nm from the viewpoint of developing photocatalytic properties and reducing spectral reflectance.

The thickness of the dielectric multilayer film (total thickness when multiple layers are laminated) is preferably within the range of 50 nm to 5 μm. If the thickness is 50 nm or more, antireflection optical properties can be exhibited, and if the thickness is 5 μm or less, surface deformation due to the film stress of the multilayer film itself can be prevented. Preferably, it is in the range of 100 nm to 1 μm.

As a method for forming a thin film such as a metal oxide on a substrate, an inorganic material is subjected to a sputtering method (for example, a reactive sputtering method such as magnetron cathode sputtering, flat plate magnetron sputtering, bipolar AC flat plate magnetron sputtering, bipolar AC rotating magnetron sputtering, etc.). ), vapor deposition (e.g., resistance heating vapor deposition, electron beam vapor deposition, ion beam vapor deposition, plasma assisted vapor deposition, and vacuum vapor deposition using IAD method), thermal CVD method, catalytic chemical vapor deposition method (Cat-CVD ), capacitively-coupled plasma CVD (CCP-CVD), optical CVD, plasma CVD (PE-CVD), epitaxial growth, atomic layer deposition, and other chemical vapor deposition methods.
In the present invention, the vacuum deposition method (IAD method) using the IAD method is preferred.

The IAD method is a method in which high kinetic energy of ions is applied during film formation to form a dense film or to enhance adhesion of the film. In this method, a deposition material is accelerated by gas molecules to form a film on the substrate surface. The IAD method is also called an “ion beam assist method”.

FIG. 2 is a schematic diagram showing an example of a vacuum deposition apparatus using the IAD method.

A vacuum vapor deposition apparatus 1 using the IAD method (hereinafter also referred to as an IAD vapor deposition apparatus in the present invention) has a dome 3 inside a chamber 2 along which a substrate 4 is arranged. The vapor deposition source 5 is provided with an electron gun or a resistance heating device for evaporating the vapor deposition material. At that time, an ion beam 8 is irradiated from an IAD ion source 7 toward the substrate, and the high kinetic energy of the ions is applied during the film formation to form a dense film or increase the adhesion of the film.

An example of the substrate 4 is glass.

A plurality of deposition sources 5 may be arranged at the bottom of the chamber 2 . Although one vapor deposition source is shown as the vapor deposition source 5 here, the number of vapor deposition sources 5 may be plural. A deposition material 6 is generated from the deposition material (evaporation material) of the deposition source 5 by an electron gun, and the deposition material is scattered and adhered to a substrate 4 (for example, a glass plate) installed in the chamber 2 to form a film. A layer made of a material (for example, a SiO _{2 ,} MgF ₂ or Al ₂ O ₃ layer that is a low refractive index material of the antireflection layer AR, or a high refractive index material such as Ta ₂ O ₅ or TiO ₂ ). A film is formed on the substrate 4 . Further, it is preferable to use a vacuum deposition method using the same IAD method for the high refractive index layers H(2) and H(4) according to the present invention.

In addition, the chamber 2 is provided with an evacuation system (not shown), which evacuates the inside of the chamber 2 . The degree of pressure reduction in the chamber is usually 1×10 ⁻⁴ to 1×10 ⁻¹ Pa, preferably 1×10 ⁻³ to 1×10 ⁻² Pa.

The dome 3 holds at least one holder (not shown) that holds the substrate 4, and is also called a vapor deposition umbrella. The dome 3 has an arcuate cross section, and has a rotationally symmetrical shape that passes through the center of a chord connecting both ends of the arc and rotates about an axis perpendicular to the chord. When the dome 3 rotates around the axis at a constant speed, for example, the substrate 4 held by the dome 3 via the holder revolves around the axis at a constant speed.

The dome 3 can hold a plurality of holders side by side in the rotation radial direction (revolution radial direction) and the rotation direction (revolution direction). As a result, it is possible to form films simultaneously on a plurality of substrates 4 held by a plurality of holders, thereby improving the manufacturing efficiency of the device.

The IAD ion source 7 is a device that introduces argon or oxygen gas into its main body, ionizes these gases, and irradiates the substrate 4 with the ionized gas molecules (ion beam 8 ). As the ion source, a Kaufmann type (filament), a hollow cathode type, an RF type, a bucket type, a duoplasmatron type, or the like can be applied. By irradiating the substrate 4 with the above gas molecules from the IAD ion source 7, the molecules of the film-forming material evaporated from, for example, a plurality of evaporation sources can be pressed against the substrate 4, and a film with high adhesion and high density can be formed on the substrate. 4 can be deposited. The IAD ion source 7 is installed at the bottom of the chamber 2 so as to face the substrate 4, but may be installed at a position shifted from the facing axis.

The ion beam used in the IAD method tends to be used in a lower degree of vacuum and at a lower acceleration voltage than the ion beam used in the ion beam sputtering method. For example, an ion beam with an acceleration voltage of 100-2000 V, an ion beam with a current density of 1-120 μA/cm ² , or an ion beam with an acceleration voltage of 500-1500 V and a current density of 1-120 μA/cm ² can be used. In the film forming process, the ion beam irradiation time can be, for example, 1 to 800 seconds, and the ion beam particle irradiation number can be, for example, 1×10 ¹³ to 5×10 ¹⁷ particles/cm ² . The ion beam used in the film formation process can be an oxygen ion beam, an argon ion beam, or an ion beam of a mixed gas of oxygen and argon. For example, it is preferable to set the amount of introduced oxygen to 30 to 60 sccm and the amount of argon to be introduced in the range of 0 to 10 sccm.

A monitor system (not shown) monitors the wavelength characteristics of the layers formed on the substrate 4 by monitoring the layers that evaporate from the vapor deposition sources 5 and adhere to themselves during vacuum film formation. . With this monitor system, it is possible to grasp the optical properties of the layers formed on the substrate 4 (for example, spectral transmittance, spectral reflectance, optical layer thickness, etc.). The monitoring system also includes a quartz layer thickness monitor to monitor the physical layer thickness of layers deposited on the substrate 4 . This monitor system also functions as a control unit that controls ON/OFF switching of the plurality of evaporation sources 5, ON/OFF switching of the IAD ion source 7, etc., according to the layer monitoring results.

[1.3] Substrate Specifically, as the substrate according to the present invention, it is preferable to apply glass, and it is preferable to use glass that is used for ordinary optical lenses.
As the glass, for example, glass such as quartz, borosilicate glass, or chemically strengthened glass is preferably used.

The thickness of the substrate according to the present invention (total thickness in the case of a laminated structure of two or more layers) is preferably 10 to 200 μm, more preferably 20 to 150 μm.

[2] Optical member for in-vehicle or outdoor use The optical member of the present invention includes an optical lens for in-vehicle or outdoor use, and in particular, a lens for an in-vehicle camera (a lens constituting a lens unit). preferable.

"On-board camera" means a camera installed on the outside of the vehicle body of an automobile, which is installed in the rear part of the vehicle body and used for checking the rear, or installed in the front part of the vehicle body and used for checking the front. Or it is used for checking the side or for checking the distance to the vehicle in front.

Such a lens unit for an in-vehicle camera is composed of a plurality of lenses. More specifically, it is composed of an object-side lens arranged on the object side and an image-side lens group arranged on the image side. The image-side lens group includes a plurality of lenses and an aperture provided between the lenses.

Among such a plurality of lenses, the object-side lens has an exposed surface exposed to the outside air, and the optical member of the present invention is used as the lens having this exposed surface.

Examples of applications of the optical member include outdoor surveillance cameras, and the optical member of the present invention is used as a lens having an exposed surface exposed to the outside air among the lenses constituting the surveillance camera. be done.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these. In the examples, "parts" or "%" are used, but "mass parts" or "mass%" are indicated unless otherwise specified.

<Preparation of optical member sample>
Vapor deposition by the IAD method was carried out under the following conditions using the IAD vapor deposition apparatus shown in FIG.

In addition, deposition film formation was performed using only the deposition source 5 in FIG. 2 without using the IAD. Table I summarizes the film formation conditions and the refractive indices for the d-line of the film formation materials.

The film-forming materials used in the examples are as follows.

<Deposition material>
YF ₃ : Product name YF ₃ manufactured by Merck
SiO ₂ : trade name SiO ₂ manufactured by Merck
OA600: Product name: OA600 Ta ₂ O ₅ , TiO, Ti ₂ O ₅ mixture manufactured by Canon Optron Co., Ltd. TiO ₂ : Product name: Ti ₃ O ₅ manufactured by Fuji Titanium Co., Ltd.
MgF ₂ : trade name MgF ₂ manufactured by Merck
<substrate>
TAF1: manufactured by HOYA <Formation of dielectric multilayer film>
(Conditions inside the chamber)
Heating temperature 340℃
Initial degree of vacuum 3.0×10 ⁻³ Pa
(Evaporation source of film-forming material)
electron gun

<Optical member No. Preparation of 1>
(Antireflection layer AR: Formation of low refractive index layer and high refractive index layer)
Film forming material for low refractive index layer: _SiO2
The above base material is placed in a vacuum deposition apparatus, the first evaporation source is loaded with the film forming material, the film is deposited at a film forming rate of 4 Å/sec, and a low refractive index film having a thickness of 36.7 nm is deposited on the base material. formed a layer.

The formation of the low refractive index layer is performed by the IAD method, with an acceleration voltage of 1000 V, an acceleration current of 1000 mA, and a neutralization (bias) current of 1200 mA. Using. The amount of gas introduced during vapor deposition was 2×10 ⁻² PA, and the IAD introduced gas was O ₂ 50 sccm, Ar gas 0 sccm, and neutral gas O ₂ 50 sccm.

Film forming material for high refractive index layer: A600
The base material was placed in a vacuum deposition apparatus, the film-forming material was loaded into the second evaporation source, and the film-forming material was deposited at a film-forming rate of 2.0 Å/sec. A high refractive index layer of 0 nm was formed. The formation of the high refractive index layer was similarly performed by the IAD method.

On the high refractive index layer formed above, a low refractive index layer and a high refractive index layer were laminated under the layer thickness conditions shown in Table I to prepare a total of 5 dielectric multilayer films.

(Photocatalytic Layer: Formation of High Refractive Index Layer H(2) or High Refractive Index Layers H(2) and H(4))
Photocatalyst layer deposition material: _TiO2
A third evaporation source is loaded with the film-forming material on the base material on which up to the five layers have been formed, and vapor deposition is performed at a film-forming rate of 2.0 Å/sec to form a film having a thickness of 129.3 nm on the low refractive index layer. A photocatalyst layer H(4) was formed. The photocatalyst layer was similarly formed by the IAD method at an acceleration voltage of 500 V, an acceleration current of 500 mA, and a neutralization (bias) current of 750 mA.

Similarly, a high refractive index layer H(2) having a photocatalytic property of 121.0 nm was formed.

(Top Layer: Formation of Low Refractive Index Layer L(1) and Intermediate Layer L(3))
Deposition material for top and middle layers: _YF3
On the substrate on which the lower layer has been formed, the film-forming material is loaded in the fourth evaporation source, vapor-deposited at a film-forming rate of 4.0 Å / sec, and a top layer with a thickness of 80.6 nm on the photocatalyst layer The intermediate layer L(3) with a thickness of 121.0 nm was formed in the same manner.

<Optical member sample No. 2 to No. Preparation of 16>
Optical member sample no. A dielectric multilayer film having the layer structure and layer thickness shown in Tables II and III was formed in the same manner as in the preparation of optical member sample No. 1. 2 to No. 16 was made.

The optical members using SiO ₂ and MgF ₂ as low refractive index materials were vapor-deposited using an electron gun at deposition rates of 2.2 Å/sec and 4.0 Å/sec, respectively.

≪Evaluation≫
The obtained optical member sample No. 1 to No. 16 was used to perform the following evaluations.

(1) Measurement of spectral reflectance In the light wavelength range of 380 to 780 nm, the spectral reflectance for light incident from the normal direction is measured using an Olympus microspectrometer USPM-RU III, and the visible Spectral reflectance values for each 10 nm in the light region (420 to 680 nm) were extracted and averaged to obtain an average spectral reflectance.

The measurement results are shown in FIGS. 3 to 6. FIG. Ranking was carried out from the shape of the spectral reflectance. A grade of △ or higher was considered acceptable, but a grade of ◯ to ◎ is desirable.
◎: The average spectral reflectance in the visible light range is 0.5% or less, which is excellent: Fig. 3
○: Although the spectral reflectance in the visible light region is slightly disturbed, the average spectral reflectance is 1.0% or less and there is no problem: Fig. 4
Δ: Although the spectral reflectance in the visible light region is disturbed, the average spectral reflectance is 1.5% or less, and there is no practical problem: FIG.
×: The spectral reflectance in the visible light region is greatly disturbed, the average spectral reflectance exceeds 1.5%, and there is a problem in practical use: FIG.

(2) Salt spray test The following evaluation was performed using the obtained optical member sample.

<Salt spray test>
The following (a) to (c) were regarded as one cycle, and 8 cycles were carried out.
(a) At a spray layer temperature of 35±2° C., a solvent of 25±2° C. is sprayed onto the uppermost layer side of the optical member sample for 2 hours.
(b) After spraying, leave at 40±2° C. and 95% RH for 22 hours.
(c) After repeating (a) and (b) four times, it is left at 25° C. and 55% RH for 72 hours.
<solvent>
Solutes used: NaCl, _MgCl2 , _CaCl2
Solute concentration: 5 ± 1 mass%

<Measurement of spectral reflectance>
The spectral reflectance of the optical member sample was measured before and after the salt spray test, and if the average value of the spectral reflectance in the light wavelength range of 420 to 680 nm varied within 0.1%, it was evaluated as a pass, and 0. When the variation was more than 0.1% and within 0.15%, it was rated as Δ, and when the variation exceeded 0.15%, it was rated as x. △ or more was set as the pass.

(3) Photocatalyst effect evaluation method The following evaluation was performed using the obtained optical member sample.

(a) Illumination Arrangement FIG. 7 shows a schematic diagram of an illumination device 200 for evaluation.

A UV light 202 is installed in the black housing 201 .

The uppermost marker surface 205 of the manufactured optical member sample 204 is placed on the flat plate 203 with the UV light 202 side.

The height is adjusted so that the distance between the UV light 202 and the optical member sample 204 is 30 mm.

(b) How to paint with pen A line is drawn on the photocatalyst surface with The Visualiser pen of Ink intelligent.

Rather than drawing a line, do it with the image of dropping ink in dots.

Ink is applied in about 5 points x 2 stages in 1 stage.

(c) UV Light Irradiation When a UV light (BL20 manufactured by YAZAWA) is plugged in, the lamp lights up.

At a height of 30 mm, UV light is irradiated with an integrated light amount of 10 J for 1 h.

Check the color change after 1 hour and 2 hours.

(d) Color evaluation Since the color is not stable immediately after taking out, the color change at each time is evaluated after 30 minutes or more have passed after taking out. When there is a photocatalytic effect, the color change is from blue to transparent (photocatalytic effect "Yes").
The evaluation rank is as follows, and 〇 or higher is a pass.
◎: Color change 5 in Fig. 7(c) and the photocatalyst effect is particularly excellent ○: Color change 4 in Fig. 7(c) and the photocatalyst effect is excellent △: Color change 3 in Fig. 7(c) and the photocatalyst effect is slightly inferior ×: Color change 2 in FIG. 7(c), and the photocatalyst effect is inferior

(4) Measurement of contact angle with water Using the obtained optical member sample, the contact angle with water of the uppermost layer was determined.

The contact angle of water was measured by a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., product Using a DropMaster DM100), the pure water contact angle was measured one minute after 1 μl of pure water was dropped. In addition, it is the value which measured seven times and averaged five measured values except the maximum value and minimum value of a measured value.
In order for the uppermost layer to exhibit hydrophilicity, the contact angle is preferably 30° or less.

(5) Comprehensive Evaluation As a comprehensive evaluation of spectral reflectance, salt spray test, and photocatalytic effect, optical members having at least one failure level x performance and optical members having two or more evaluation levels Δ were taken as comparative examples.

An optical member having one evaluation level of Δ is within the scope of the present invention, but the overall evaluation is Δ.

Tables II and III below show the configuration, production method, and evaluation results of the optical member samples.

From Tables II and III, it can be seen that optical member samples No. 1, 2, 6, 7, 9 to 13, and 15 are superior to the comparative examples in spectral reflectance and salt water resistance, and furthermore, a TiO ₂ -containing layer is provided in the optical member as a photocatalyst layer. It can be seen that the photocatalytic effect is exhibited and the self-cleaning property is also excellent.

On the other hand, the optical member 4 having SiO ₂ as the uppermost layer was inferior in resistance to salt water, and the optical member 5 using MgF ₂ as the intermediate layer L(3) was inferior in photocatalytic properties.

1 IAD deposition apparatus 2 chamber 3 dome 4 substrate 5 deposition source 6 deposition material 7 IAD ion source 8 ion beam 100 optical member dielectric multilayer film 101 substrate 102 low refractive index layer 103 high refractive index layer 104 low refractive index layer 105 high refractive index index layer 106 low refractive index layer 107 antireflection layer AR
108 High refractive index layer H (2)
109 Low refractive index layer L (1)
110 High refractive index layer H (4)
111 Low refractive index layer L (3)
115 Dielectric multilayer film 200 Photocatalyst evaluation device 201 Black housing 202 UV lamp 203 Flat plate 204 Optical member sample 205 Marker surface 206 Ink

Claims (8)

An optical member having a dielectric multilayer film on a substrate,
The dielectric multilayer film has a low refractive index layer L (1), a high refractive index layer H (2), and an antireflection layer AR from at least the surface,
The low refractive index layer L (1) has a refractive index of less than 1.7 for the helium d-line, and the high refractive index layer H (2) has a refractive index of 1.7 or more for the helium d-line,
At least the low refractive index layer L(1) contains yttrium fluoride (YF ₃ ),
The high refractive index layer H(2) contains a photocatalytic metal oxide, and the thickness of the high refractive index layer H(2) is in the range of 200 to 550 nm. optical components. An optical member having a dielectric multilayer film on a substrate,
The dielectric multilayer film includes, from at least the surface, a low refractive index layer L(1), a high refractive index layer H(2), a low refractive index layer L(3), a high refractive index layer H(4), and an antireflection layer. is the configuration of the AR,
The low refractive index layers L(1) and L(3) have a refractive index of less than 1.7 for the helium d-line, and the high refractive index layers H(2) and H(4) have a refractive index for the helium d-line. ratio is 1.7 or more,
The low refractive index layers L(1) and L(3) contain yttrium fluoride (YF ₃ ),
The high refractive index layers H(2) and H(4) contain photocatalytic metal oxides, and the sum of the thicknesses of the high refractive index layers H(2) and H(4) is 200. An optical member characterized in that it is within the range of ~550 nm. 3. The optical member according to claim 1, wherein the metal oxide is titanium oxide ( _TiO2 ). 4. The optical member according to any one of claims 1 to 3, wherein the thickness of the low refractive index layer L(1) is within the range of 60 to 120 nm. 5. The optical member according to any one of claims 2 to 4, wherein the thickness of the low refractive index layer L(3) is within the range of 3 to 23 nm. 6. The optical member according to any one of claims 1 to 5, wherein the antireflection AR has a layer containing at least silicon oxide ( _SiO2 ). 7. The method according to any one of claims 1 to 6, wherein the average spectral reflectance for light incident from the normal direction is 1.5% or less in the light wavelength range of 420 to 680 nm. optical member. An optical member manufacturing method for manufacturing the optical member according to any one of claims 1 to 7,
A method for producing an optical member, wherein the layer containing TiO ₂ and the layer containing SiO ₂ are formed using an ion-assisted deposition method.

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