Patent Description:
<CIT> describes a spectacle lens that reduces a burden on the eye due to infrared rays contained in sunlight ([<NUM>] of <CIT>). This document describes that a reflectance of a multilayer film formed on a surface of a lens substrate is set in consideration of the strength of sunlight infrared rays in each wavelength region ([<NUM>] of <CIT>).

<CIT> describes that by inclusion of a near-infrared ray cut function filter in a lens portion, spectacle that prevent invasion of near-infrared rays into the eyeball as much as possible and are soft on the eye are provided ([<NUM>] of <CIT>).

The near-infrared ray cut function filter described in <CIT> blocks near infrared rays in a short wavelength region among near infrared rays having a wavelength range of <NUM>-<NUM> with a first multilayer film formed on one surface of a transparent substrate (lens substrate). In addition, the near-infrared ray cut function filter blocks near-infrared rays in a long wavelength region with a second multilayer film formed on the other surface ([<NUM>] of <CIT>).

That is, in <CIT>, light blocking is shared by both surfaces with a near-infrared wavelength of <NUM> as a boundary ([<NUM>] of <CIT>).

Another document disclosing a spectacle lens that reduces the amount of infrared rays reaching the eye is <CIT>.

There is a demand for imparting, to an eyeball-side surface of a spectacle lens, not only a near-infrared reduction function (hereinafter also referred to as IR cut function) but also a function of suppressing reflection of ultraviolet light on the eyeball-side surface (hereinafter also referred to as low UV reflection) such that ultraviolet light incident from the eyeball-side surface side does not enter the eye of a wearer by reflection.

An object of the present invention is to ensure IR cut function and low UV reflection on an eyeball-side surface.

The present inventor made intensive studies to solve the above problems. As a result, the present inventor has found that while IR cut function is imparted to multilayer films on both surfaces, the height of IR cut function is intentionally reduced by one step in a multilayer film on an eyeball-side surface, and low UV reflection is imparted to the multilayer film on the eyeball-side surface. The present inventor has found that the above problems can be solved by the above configuration.

The present invention has been found based on the above findings. The present invention thus provides a lens, which is a spectacle lens comprising multilayer films on an object-side surface and an eyeball-side surface of a lens substrate, wherein.

Preferred embodiments of the present invention are as defined in the appended dependent claims and/or in the following detailed description.

According to the present invention, IR cut function and low UV reflection on the eyeball-side surface can be ensured.

Herein, a mean reflectance means an arithmetic mean value of normal incidence reflectances measured for each arbitrary wavelength (with an arbitrary pitch) in a wavelength range to be measured at the optical center of a surface to be measured. For the measurement, a measurement wavelength interval (pitch) can be arbitrarily set in a range of, for example, <NUM>-<NUM>. Also, herein, a reflection spectral characteristic such as a reflectance means a normal incidence reflection spectral characteristic. "Luminous reflectance" is measured in accordance with JIS T <NUM>:<NUM>.

Herein, "eyeball-side surface" means a surface disposed on an eyeball side and "object-side surface" means a surface disposed on an object side when a wearer wears spectacles including a spectacle lens.

Herein, "to" refers to a predetermined value or more and a predetermined value or less.

Hereinafter, the spectacle lens of the present invention (also referred to as "the present spectsacle lens" hereinafter) will be described.

The present spectacle lens is a spectacle lens comprising multilayer films on an object-side surface and an eyeball-side surface of a lens substrate, wherein.

First, it is assumed that a reduction ratio of light in a wavelength band of <NUM>-<NUM> is set to ≥ <NUM>% when light passes through both surfaces of the spectacle lens, that is, the spectacle lens as a whole has a sufficient IR cut function. The reduction ratio (%) is (<NUM> - transmittance value) (%).

Meanwhile, in the wavelength band of <NUM>-<NUM>, a ratio of the mean reflectance on the eyeball-side surface of the spectacle lens to the mean reflectance on the object-side surface of the spectacle lens is set to <NUM>-<NUM> (preferably <NUM> (more preferably > <NUM>), more preferably <NUM> (more preferably > <NUM>) as a lower limit, and set to preferably < <NUM> as an upper limit). That is, while IR cut function is imparted to the multilayer films on both surfaces, the height of IR cut function is intentionally reduced by one step in the multilayer film on the eyeball-side surface. The above ratio indicates this reduction by one-step.

By setting a mean reflectance on the eyeball-side surface in a wavelength band of <NUM>-<NUM> to ≤ <NUM>% (preferably < <NUM>%, more preferably ≤ <NUM>%), low UV reflection is imparted to the multilayer film on the eyeball-side surface.

Hereinafter, a preferred example of the present invention will be described, and details of the configuration of the present spectacle lens will be described.

The reflectance on each surface of the spectacle lens preferably has at least one maximum value in a wavelength band of <NUM>-<NUM>. This maximum value (the largest maximum value when there is a plurality of maximum values) is also preferably a maximum value in the wavelength band of <NUM>-<NUM>. This requirement indicates that IR cut function having the same tendency in a relationship between wavelength and reflectance (for example, when the horizontal axis indicates wavelength (nm) and the vertical axis indicates reflectance (%), plots between wavelength and reflectance draw a convex shape upward when viewed macroscopically) is imparted to the multilayer films on both surfaces. By meeting this requirement, IR cut function is ensured because light in the wavelength band of <NUM>-<NUM> is effectively reflected on the multilayer films on both surfaces.

By the way, in order to specify that the plots between wavelength and reflectance macroscopically draw a convex shape upward, a requirement that smoothed plots in the wavelength band of <NUM>-<NUM> in the plots between wavelength and reflectance have at least one (for example, one) maximum value may be provided. This smoothing may be performed, for example, by taking a running mean of reflectances at <NUM> points before and after predetermined point a in the plots (that is, <NUM> points in total including point a), and using the running mean value as a new reflectance at point a. As a result, it is possible to exclude a case where there is a plurality of maximum values due to fine vibration in the plots, and to specify that the plots between wavelength and reflectance macroscopically draw a convex shape upward.

The reflectance on each surface of the spectacle lens preferably has at least one maximum value in a wavelength band of <NUM>-<NUM> in addition to the above wavelength band. This requirement indicates that characteristics of the same tendency are imparted to the multilayer films on both surfaces in that green (<NUM>-<NUM>) reflected light more specifically, interference light) is generated. By meeting this requirement, the accuracy of visual inspection of a spectacle lens can be improved.

More specifically, the visual inspection of a spectacle lens includes an inspection for examining the state of interference light by irradiating the spectacle lens with light. When red or blue interference light is generated instead of green interference light, these colors have a lower visual perception than green light, and therefore the accuracy of the visual inspection is lowered. Meanwhile, when green interference light in a wavelength band of <NUM>-<NUM> is generated as in the above example, such a risk can be eliminated.

Green reflected light is preferable to a wearer because the green reflected light has a higher psychological affinity than blue reflected light. Therefore, at least one maximum value (the largest maximum value when there is a plurality of maximum values) in the wavelength band of <NUM>-<NUM> is preferably more than <NUM>% (preferably ≥ <NUM>%).

The sum of the luminous reflectances on both surfaces of the spectacle lens is preferably ≤ <NUM>% (preferably < <NUM>%, more preferably ≤ <NUM>%, still more preferably ≤ <NUM>%). According to the above requirement, it is possible to suppress occurrence of glare due to reflected light in the spectacle lens. The luminous reflectance on each surface may be ≤ <NUM>%, or ≤ <NUM>%.

According to an aspect of the present invention, the sum of the luminous reflectances on both surfaces of the spectacle lens is ≤ <NUM>%, and one maximum value (largest maximum value) in the wavelength band of <NUM>-<NUM> may be > <NUM>%. That is, when the luminous reflectance on one surface is about <NUM>%, which is half of <NUM>%, even though the luminous reflectance on the one surface is <NUM>%, one maximum value (largest maximum value) in the green wavelength band of <NUM>-<NUM> may be > <NUM>%. This makes it possible to generate green interference light at a pinpoint while suppressing the luminous reflectance.

The mean reflectance in a wavelength band of <NUM>-<NUM> (UVA) on the eyeball-side surface of the spectacle lens may be ≤ <NUM>%. According to this requirement, the mean reflectance in UVA in UV can be suppressed, and therefore low UV reflection can be achieved more reliably. Generally, when high IR cut function is imparted to a multilayer film, UV reflectance (UVA) tends to be high. Meanwhile, in an aspect of the present invention, IR cut function on the eyeball-side surface is intentionally reduced by one step. Instead, low UV reflection (UVA) is achieved, and the luminous reflectance is suppressed to a low value.

The mean reflectance in a wavelength band of <NUM>-<NUM> (UVA) on the object-side surface of the spectacle lens may be ≥ <NUM>%.

The mean reflectance in a wavelength band of <NUM>-<NUM> (UVB) on the object-side surface of the spectacle lens may be ≥ <NUM>%.

A multilayer film on each surface of the spectacle lens includes one or more high refractive index layers and one or more low refractive index layers, and the total number of layers is ≤ <NUM> (preferably ≤ <NUM>).

Specific matters other than the above matters will be described below.

In the spectacle lens, the multilayer film formed on each of the eyeball-side surface and the object-side surface of the lens substrate can impart the above reflection spectral characteristic to the spectacle lens. The multilayer film is formed on a surface of the lens substrate directly or indirectly through one or more other layers. The lens substrate is not particularly limited, and examples thereof include glass, a styrene resin including a (meth)acrylic resin, a polycarbonate resin, an allyl resin, an allyl carbonate resin such as diethyleneglycol bis(allylcarbonate) resin (CR-<NUM>), a vinyl resin, a polyester resin, a polyether resin, a urethane resin obtained through reaction between an isocyanate compound and a hydroxy compound such as diethylene glycol, a thiourethane resin obtained through reaction between an isocyanate compound and a polythiol compound, and a transparent resin obtained by curing a polymerizable composition containing a (thio) epoxy compound having one or more intermolecular disulfide bonds. In addition, inorganic glass can also be used. Note that the lens substrate may be undyed (a colorless lens) or dyed (a dyed lens). The refractive index of the lens substrate is, for example, approximately <NUM>-<NUM>. Provided that the refractive index of the lens substrate is not limited thereto but may be within the above range or deviate therefrom.

The spectacle lens can be various lenses such as a monofocal lens, a multifocal lens, and a progressive addition lens. The type of the lens is determined depending on the shapes of both surfaces of the lens substrate. A surface of the lens substrate may be a convex surface, a concave surface, or a flat surface. In a general lens substrate and spectacle lens, the object-side surface is a convex surface, and the eyeball-side surface is a concave surface. However, the present invention is not limited thereto.

The multilayer film for imparting the above reflection spectral characteristic may be provided on a surface of the lens substrate directly or indirectly through one or more other layers. Examples of a layer which can be formed between the lens substrate and the multilayer film include a hard coat layer (hereinafter, also referred to as "hard coat"). By forming a hard coat layer, it is possible to impart flaw resistance (abrasion resistance) to the spectacle lens and to improve durability (strength) of the spectacle lens. For details of the hard coat layer, for example, paragraphs.

[<NUM>]-[<NUM>] and [<NUM>] of <CIT> can be referred to. A primer layer may be formed between the lens substrate and the coat in order to enhance adhesion. For details of the primer layer, for example, paragraphs [<NUM>]-[<NUM>] of <CIT> can be referred to.

The multilayer film formed on each of the eyeball-side surface and the object-side surface of the lens substrate is not particularly limited as long as the multilayer film can impart the above-described reflection spectral characteristic to the spectacle lens surfaces having the multilayer films. Such a multilayer film can be preferably formed by sequentially building up a high refractive index layer and a low refractive index layer. More specifically, the multilayer film can be formed by determining the film thickness of each layer through optical simulation by a known method based on a refractive index of a film material for forming the high refractive index layer and the low refractive index layer and the wavelength of light to be reflected and light the reflection of which is to be reduced, and then sequentially building up the high refractive index layer and the low refractive index layer under film formation conditions determined such that the determined film thickness is achieved. A film forming material may be an inorganic material, an organic material, or an organic-inorganic composite material, and is preferably an inorganic material from a viewpoint of film formation and ease of availability. By adjusting the type of the film forming material, a film thickness, building order, or the like, it is possible to control the reflection spectral characteristic to each of blue light, ultraviolet rays, green light, and red light.

Examples of a high refractive index material for forming the high refractive index layer include one type of oxide selected from the group consisting of zirconium oxide (for example, ZrO<NUM>), tantalum oxide (Ta<NUM>O<NUM>), titanium oxide (for example, TiO<NUM>), aluminum oxide (Al<NUM>O<NUM>), yttrium oxide (for example, Y<NUM>O<NUM>), hafnium oxide (for example, HfO<NUM>), and niobium oxide (for example, Nb<NUM>O<NUM>), and a mixture of two or more types of oxides selected therefrom. Meanwhile, examples of a low refractive index material for forming the low refractive index layer include one type of oxide or fluoride selected from the group consisting of silicon oxide (for example, SiO<NUM>), magnesium fluoride (for example, MgF<NUM>), and barium fluoride (for example, BaF<NUM>), and a mixture of two or more types of oxides and fluorides selected therefrom. Note that in the above examples, oxide and fluoride are expressed in a stoichiometric composition for convenience, but oxide or fluoride in which oxygen or fluorine is deficient or excessive as compared to the stoichiometric composition can also be used as the high refractive index material or the low refractive index material.

The film thickness of each layer included in the multilayer film can be determined through optical simulation as described above. Examples of a layer configuration of the multilayer film include:.

Each of the layers is preferably a coat including the above-described high refractive index material or low refractive index material as a principal component. Here, the principal component is a component which accounts for the largest part of the coat and generally accounts for approximately <NUM>-<NUM>% by mass, or furthermore <NUM>-<NUM>% by mass with respect to the total amount. Such a coat can be formed by film formation using a film forming material including the above material as a principal component (for example, a vapor deposition source). Note that the principal component of the film forming material is similar to the above. The coat and the film forming material may include a minute amount of impurities which are inevitably mixed, and may include another component such as another inorganic substance or a known additive component which supports film formation as long as the component does not impair the function of the principal component. The film formation can be performed by a known film formation method, and is preferably performed by vapor deposition from a viewpoint of ease of the film formation. The vapor deposition in the present invention includes a dry method such as a vacuum vapor deposition method, an ion plating method, or a sputtering method. In the vacuum vapor deposition method, an ion beam assist method for emitting an ion beam simultaneously with vapor deposition may be used.

The multilayer film can also include, in addition to the above-described high refractive index layer and low refractive index layer, a coat including a conductive oxide as a principal component, preferably one or more conductive oxide layers formed by vapor deposition using a vapor deposition source including a conductive oxide as a principal component at an arbitrary position in the multilayer film. As the conductive oxide, various conductive oxides generally known as transparent conductive oxides, such as indium oxide, tin oxide, zinc oxide, titanium oxide, or composite oxide thereof, are preferably used from a viewpoint of transparency of the spectacle lens. Particularly preferable examples of the conductive oxide include tin oxide and indium-tin oxide (ITO) from viewpoints of transparency and conductivity. By including the conductive oxide layer, it is possible to prevent adherence of dust to the charged spectacle lens.

A functional film can be further formed on the multilayer film. Examples of such a functional film include various functional films such as a water repellent or hydrophilic antifouling film, an anti-fogging film, a polarizing film, and a photochromic film. A known technique can be applied to any of these functional films without any restriction.

According to another aspect, it is possible to provide spectacles including the present spectacle lens and a frame equipped with the spectacle lens. The spectacle lens has been described above in detail. A known technique can be applied to other components of the spectacles without any restriction.

According to another aspect, it is also possible to provide a method for manufacturing the present spectacle lens.

The present invention will be further described with Examples below. In the following description, the refractive index is a refractive index at a wavelength of <NUM>.

On a hard coat surface on a convex surface side (object side) of a plastic lens substrate (trade name: EYAS manufactured by HOYA Corporation, refractive index: <NUM>, colorless lens) in which both surfaces had been optically finished and subjected to hard coating in advance, the object-side surface was a convex surface, and the eyeball-side surface was a concave surface, a multilayer vapor deposition film having eight layers in total was sequentially formed by ion assisted deposition using an oxygen gas (O<NUM>) and an argon gas (Ar) as assist gases.

On the hard coat surface on the concave surface side (eyeball side), a multilayer vapor deposition film having seven layers in total was also layered by the ion assisted deposition under similar conditions, and a spectacle lens was thus obtained.

In the present Example, the multilayer vapor deposition film was formed such that, on each side of the convex surface side and the concave surface side, a first layer, a second layer. were layered in this order from the lens substrate side (hard coat side) to the spectacle lens surface and the outermost layer on the spectacle lens surface side was to be an eighth layer using any of the vapor deposition sources illustrated in Table <NUM>. In the present Example, the vapor deposition sources formed of the following oxides were used except for impurities which may be inevitably mixed. In the present Example, the reflection spectral characteristic was controlled by changing the film thicknesses of the following one or more layers.

Table <NUM> below illustrates the physical film thickness and the optical film thickness of the multilayer film on each of the object-side surface and the eyeball-side surface in addition to the vapor deposition source.

In the optical center of each of the object-side surface (convex surface side) and the eyeball-side surface (concave surface side) of the spectacle lens of the present Example, a spectroscopic reflection spectrum and a transmission spectrum in a wavelength range of <NUM>-<NUM> were measured (measurement pitch: <NUM>) using a spectrophotometer F10-AR manufactured by Filmetrics and a Hitachi spectroaltimeter U-<NUM> in combination. In order to suppress reflection from a non-measurement surface, the non-measurement surface was painted with lusterless black as described in Section <NUM> of JIS T <NUM>.

<FIG> is a diagram illustrating spectral reflection spectra obtained by measurement on the object-side surface and the eyeball-side surface of the spectacle lens of Example <NUM>.

<FIG> is a diagram illustrating a transmission spectrum obtained by measuring the spectacle lens of Example <NUM>.

In the present Example, as illustrated in <FIG>, the condition that the reduction ratio of light in the wavelength band of <NUM>-<NUM> is ≥ <NUM>% in the spectacle lens according to an aspect of the present invention is clearly satisfied (accurate value is <NUM>%). In addition, as illustrated in <FIG>, the condition that the ratio of a mean reflectance on the eyeball-side surface of the spectacle lens to a mean reflectance on the object- side surface of the spectacle lens is <NUM>-<NUM> in the wavelength band of <NUM>-<NUM> in the spectacle lens according to an aspect of the present invention is satisfied.

In addition, the condition that a mean reflectance on the eyeball-side surface in a wavelength band of <NUM>-<NUM> is <NUM>% or less is also satisfied (accurate value is <NUM>%). Furthermore, the sum of luminous reflectances on both surfaces in the optical multilayer film at this time is <NUM>% (<NUM>% on the object-side surface and <NUM>% on the eyeball-side surface). This indicates that reflection is sufficiently suppressed on both surfaces, and a favorable wearing feeling is achieved as the spectacle lens.

In the present Example, the ratio of a mean reflectance on the eyeball-side surface of the spectacle lens to a mean reflectance on the object-side surface of the spectacle lens was set to <NUM> in a wavelength band of <NUM>-<NUM>. Reference Example <NUM> was performed in a similar manner to Example <NUM> except for this.

Table <NUM> below illustrates the physical film thickness and the optical film thickness of the multilayer film on each of the object-side surface and the eyeball-side surface in addition to the vapor deposition sources for the present Example and Reference Example <NUM> below.

In the present Example, the ratio of a mean reflectance on the eyeball-side surface of the spectacle lens to a mean reflectance on the object-side surface of the spectacle lens was set to <NUM> in a wavelength band of <NUM>-<NUM>. Example <NUM> was performed in a similar manner to Example <NUM> except for this.

<FIG> is a diagram illustrating spectral reflection spectra obtained by measurements on object-side surfaces and eyeball-side surfaces of spectacle lenses of Examples <NUM>-<NUM> and Reference Examples <NUM> and <NUM>.

In Reference Examples <NUM> and <NUM>, as illustrated in <FIG>, low UV reflection on the eyeball-side surface could not be ensured. Meanwhile, in Examples <NUM>-<NUM>, as illustrated in <FIG>, low UV reflection on the eyeball-side surface could be ensured, and favorable IR cut performance could be exhibited. Although Example <NUM> is not illustrated in <FIG>, the mean reflectance on the eyeball-side surface in a wavelength band of <NUM>-<NUM> was <NUM>%, and the mean reflectance in a wavelength band of <NUM>-<NUM> was <NUM>%. Therefore, low UV reflection on the eyeball-side surface could be ensured while favorable IR cut performance was exhibited.

Claim 1:
A lens, which is a spectacle lens comprising multilayer films on an object-side surface and an eyeball-side surface of a lens substrate, wherein
- the reduction ratio by reflection of light in a wavelength band of <NUM>-<NUM> in the lens is ≥ <NUM>%,
- the ratio of a mean reflectance on the eyeball-side surface of the lens to that on the object-side surface of the lens is <NUM>-<NUM> in the wavelength band, and
- the mean reflectance on the eyeball-side surface in a wavelength band of <NUM>-<NUM> is ≤ <NUM>%.