JPH10268107A - Synthetic resin lens with antireflection film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the deformation of a synthetic resin lens substrate having an antireflection film and widen a low reflection wavelength range. SOLUTION: This lens has a QHQ type antireflection film with an intermediate refraction factor layer, a high refraction factor layer and a low refraction factor layer respectively stacked in order on a lens substrate made of synthetic resin. In this case, the high refraction factor layer is formed to have the refraction factor changed in a thicknesswise direction, so that the factor at wavelength as the center of the design becomes lower by a value between 0.01 and 0.20 on surface side than on the lens substrate side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a synthetic resin lens provided with an antireflection film.

[0002]

2. Description of the Related Art In synthetic resin lenses such as spectacle lenses and camera lenses, in order to prevent flicker and ghost due to reflection on the surface of the synthetic resin lens, an anti-reflection film is applied to the surface of the synthetic resin lens as much as possible. There is a need to reduce surface reflections. Therefore, conventionally, in order to obtain an effective anti-reflection effect in the visible light region,
At a wavelength λc, which is the center of the design, a QHQ film configuration in which the optical film thickness is λc / 4, λc / 2, λc / 4 from the substrate side,
Alternatively, the optical film thickness is set to λc / 4, λc / 4, λc / 4 from the substrate side.
An antireflection film having a QQQ film configuration described above is often used. As the material constituting the film, a material having an appropriate refractive index is selected so that a sufficient antireflection effect can be obtained. Particularly, as an antireflection film capable of obtaining a low reflectance in a wide wavelength region, a low refractive index layer having a thickness of λc / 4 as an outermost layer and an inner side thereof as disclosed in US Pat. A reflection layer having a high refractive index layer having a thickness of λc / 2 as a layer and an intermediate layer having an intermediate refractive index layer having a thickness of λc / 4 or an equivalent layer composed of an equivalent film equivalent to the intermediate layer having a thickness of λc / 4. There is a protective film. In practice, there is often no suitable material for a good intermediate refractive index layer, and US Pat. No. 3,565,509 and US Pat.
As disclosed in Japanese Patent No. 225, the intermediate refractive index layer is replaced with a two-layer or three-layer equivalent film in which a low-refractive-index substance and a high-refractive-index substance are alternately laminated, and is composed of four to five layers in total. An anti-reflection film is often used.

As a method for forming such an antireflection film, a vacuum deposition method is generally and often used. When the substrate is a synthetic resin, the substrate temperature during film formation must be low (120 ° C. or lower) in order to avoid deformation of the substrate. Therefore, SiO ₂ , TiO ₂ , ZrO ₂ , Ta ₂
O ₅ , Al ₂ O _{3 and the} like are used alone or as a mixture.

Further, in order to increase the strength and the refractive index of the film, during the vapor deposition, ion beam assist vapor deposition is performed by simultaneously irradiating an ion beam of a gas such as oxygen or argon accelerated by an ion gun provided in the chamber. Is also effective. Irradiation with an ion beam has the effect of increasing the density of the film and making the crystal denser. Above all, JP 55
As disclosed in JP-A-65239 and the like, this method is extremely effective in forming a film mainly composed of an oxidized substance of Ti. By adjusting the acceleration voltage of the ion beam, the current density of the ions, and the type and amount of the gas to be introduced, a film having a high intensity and a high refractive index can be produced with good reproducibility.

In recent years, a lens made of synthetic resin, n = 1.50, which has been conventionally used in order to reduce the thickness and weight, has been used.
N = 1.55, 1.60,
Materials having a high refractive index such as 1.66 have been used.

[0006]

In order to form a low-reflection and high-performance antireflection film on these high-refractive-index synthetic resin lenses, a high-refractive-index layer having a refractive index of 2.0 or more is required. You need a rate. However, when such a high-refractive-index layer is formed by ion beam assisted vapor deposition, the temperature of 50 ° C.
Even if film formation is started at a low temperature, the temperature rises due to heating by ion beam irradiation in addition to radiant heat from the evaporation source. Therefore, there has been a problem that the substrate is likely to be deformed by heat during the formation of the high refractive index layer. In addition, a rise in the temperature during the film formation causes a rise in the refractive index in the high refractive index layer from the substrate side to the surface side, that is, a so-called positive inhomogeneity of the refractive index occurs. At this time, there is also a problem that the wavelength region of low reflection becomes narrow and the spectral characteristics deteriorate.

Therefore, an object of the present invention is to solve such a problem.

[0008]

In order to solve such a problem, a synthetic resin lens having an antireflection film according to the present invention has a λc /
The temperature is increased by adopting a thin film layer having a negative non-homogeneous refractive index distribution as the high refractive index layer of the (QHQ type) antireflection film having a thickness of 4, λc / 2, λc / 4. The rise is suppressed and the spectral characteristics are also improved.

(1) That is, in the synthetic resin lens with an antireflection film of the present invention, an intermediate refractive index layer, a high refractive index layer, and a low refractive index layer are formed on a lens substrate made of a synthetic resin. In a synthetic resin lens with an anti-reflection film provided with a QHQ-type anti-reflection film laminated in this order, the high refractive index layer is refracted at a wavelength (hereinafter, referred to as “λc”) which is the center of design. The ratio changes along the film thickness direction such that the ratio becomes lower by 0.01 to 0.20 on the surface side than on the lens substrate side.

Therefore, according to the present invention, it is possible to suppress the deformation of the substrate of the synthetic resin lens provided with the antireflection film and to widen the low reflection wavelength range. here,
.lambda.c is a wavelength which is the center of the design, and is selected from the range of about 480-550 nm when an antireflection effect is obtained in the entire visible light region. The QHQ type antireflection film has a structure in which an intermediate refractive index layer, a high refractive index layer, and a low refractive index layer are laminated in this order from the lens substrate side, and has a low reflectance in a wide wavelength region. And an antireflection film as disclosed in US Pat. No. 3,185,020. Q is the quarter, ie λc / 4,
H is half, that is, λc / 2. That is, a QHQ type antireflection film is a film in which an intermediate refractive index layer, a high refractive index layer and a low refractive index layer are λc / 4, λc / 2 and λc, respectively.
An antireflection film having an optical film thickness of c / 4. However, in the QHQ type antireflection film of the present invention, the optical thicknesses of the intermediate refractive index layer, the high refractive index layer, and the low refractive index layer are not necessarily exactly λc / 4, λc / 2, λc, respectively. It is not necessary to be / 4, and it can be selected from a range in which the antireflection characteristics as a QHQ type antireflection film can be sufficiently exhibited.

(2) The synthetic resin lens with an anti-reflection film according to claim 2 is the synthetic resin lens with an anti-reflection film according to claim 1, wherein the high refractive index layer is made of TiO ₂ or T
It is characterized in that iO ₂ is at least 20 wt% and the balance is made of ZrO ₂ , Ta ₂ O ₅ or an oxide of a rare earth element. It is desirable that the refractive index is 2.15 or more.

(3) The synthetic resin lens with an antireflection film according to claim 3 is the synthetic resin lens with an antireflection film according to claim 2, wherein the high refractive index layer is formed by oxygen ion beam assisted deposition. A high-refractive-index layer having a film formed, and a refractive-index change in a film thickness direction caused by changing an output of an ion beam or an amount of a gas to be introduced during a film-forming process; It is characterized by.

[0013] TiO ₂ is not subjected to vacuum deposition with the composition as it is, and TiO ₂ , which is less degassed and easy to evaporate,
A film of Ti ₂ O ₃ , Ti ₃ O ₅ , or a mixture of a plurality of Ti ₄ O ₇ , formed on a substrate by ion beam assisted vapor deposition containing oxygen as a main component so as to have a TiO ₂ composition, The output of the ion beam or the amount of gas to be introduced is changed during film formation to cause a change in the refractive index in the film thickness direction. When the acceleration voltage of the ions is increased, the energy of the ion beam is increased, and the density and the refractive index of the film are increased.
At this time, the temperature rise also increases. Similarly, the increase in the acceleration current increases the ion current density, increases the film density and refractive index, and increases the temperature rise. As the gas introduced into the ion source and the vacuum chamber, pure oxygen or a mixed gas containing oxygen as a main component is used, and the flow rate is adjusted within a range necessary for causing a sufficient oxidation reaction of Ti. The minimum flow rate at which light is not absorbed by the film due to insufficient oxidation varies depending on the evacuation capacity of the vapor deposition apparatus and the film formation rate. Excessive introduction of oxygen lowers the degree of vacuum and lowers the film density and the refractive index. The accelerating voltage, accelerating current and gas introduction amount of these ions can be easily controlled from outside even during film formation,
It is possible to change the physical properties of the film with good reproducibility.

In the deposition of the high refractive index layer of the present invention, a high accelerating voltage and a high accelerating current are set at the start of film formation so as to have a high refractive index, and the introduced gas is set to a minimum flow rate at which absorption does not occur. During the film formation, the acceleration voltage and / or the acceleration current are gradually decreased according to the value of the film thickness meter or the film formation time. It is also possible to gradually increase the introduced gas amount as needed. The refractive index may increase during the process, but conditions are set so that the refractive index is lower at the end of film formation than at the start and the film strength is secured. In this method, the change in the refractive index is approximately 0.1.
It can be set to decrease by about 1, and can be reduced to about 0.2 if the strength of the film is sacrificed to some extent. Spectral reflectance is good with a wide range of low reflection wavelengths compared to the case where there is positive inhomogeneity or no inhomogeneity, and the temperature rise of the substrate is small because heating by the ion beam during film formation is suppressed. can do. In addition, since the intensity of ion beam irradiation at the start of film formation is high, there is an effect that the initial crystal growth of the deposition material is fine and anisotropy is suppressed.

(4) The synthetic resin lens with an antireflection film according to claim 4 is the synthetic resin lens with an antireflection film according to any one of claims 1 to 3, wherein the lens substrate is
The refractive index at λc is 1.50 or more, and the intermediate refractive index layer has an equivalent refractive index at λc of 1.60 to 1.
90, the optical thickness of which is 0.22λc to 0.32λc, and the high refractive index layer has an equivalent refractive index at λc of 2.00 to 2.30 and an optical thickness of 0.45λc to
0.55λc, and the low refractive index layer has an equivalent refractive index of 1.43 to 1.47 at λc and an optical thickness of 0.22λc to 0.28λc.

In this range, sufficient antireflection characteristics can be exhibited as a QHQ type antireflection film.

Although various synthetic resins can be selected as the lens substrate, when the refractive index is 1.50 or less, the refractive index of the low refractive index substance becomes close to that of SiO _2. Does not provide a good antireflection effect. When the refractive index of the substrate is 1.80 or more, the wavelength band of low reflection becomes narrow, and it becomes difficult to obtain a good antireflection effect.

(5) The synthetic resin lens with an anti-reflection film according to claim 5 is the synthetic resin lens with an anti-reflection film according to any one of claims 1 to 4, wherein the intermediate refractive index layer is at λc. A low refractive index material layer having a refractive index of 1.43 to 1.47 and an optical thickness of 0.08 λc to 0.13 λc, a refractive index at λc of 2.00 to 2.30, and an optical thickness of 0 A high-refractive-index material layer having a refractive index of 0.06λc to 0.11λc and a low-refractive-index material layer having a refractive index of 1.43 to 1.47 at λc and an optical film thickness of 0.08λc to 0.13λc. It is characterized by being a three-layer laminated film.

By adopting such a structure, the intermediate refractive index layer is made of the same two kinds of materials as the material of the high refractive index layer and the material of the low refractive index, and is applicable to a synthetic resin substrate having a wide refractive index range. can do.

(6) The synthetic resin lens with an antireflection film according to claim 6 is the synthetic resin lens with an antireflection film according to any one of claims 1 to 5, wherein the low refractive index layer is made of SiO ₂ . There is a feature.

This is because the adhesiveness to the synthetic resin lens substrate is excellent, and sufficient strength can be obtained even when the film is formed at a low temperature. Si
Unless the use of O ₂ is particularly required for stability, it is preferable not to perform ion beam assisted vapor deposition in order to avoid overheating of the substrate. Even if ion beam assisted deposition is performed, irradiation with an ion beam having an extremely low output is sufficient.

The synthetic resin lens having an antireflection film of the present invention may be provided with a hard coating in which inorganic fine particles are dispersed in an organic material containing silicon in order to improve the abrasion resistance of the lens substrate. And an anti-reflection film can be laminated thereon.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

(Example 1) A lens made of sulfur-containing urethane resin having a refractive index of 1.66 was set in a vacuum chamber, and the temperature was set at 60 ° C.
While evacuating, evacuation is performed until the degree of vacuum reaches 8 × 10 ⁻⁶ Torr. After that, the accelerating voltage is 500 V and the ion current density is 2
An ion cleaning treatment was performed for 60 seconds by irradiating with an oxygen ion beam of 0 μA / cm ² . After the treatment, an antireflection film was formed with the following film configuration. The wavelength λc, which is the center of the design, is set to 520 nm, and the first layer SiO ₂ (refractive index: 1.46) is coated from the substrate side with an optical film thickness of 0.1.
00λc TiO ₂ (refractive index 2.30) to optical thickness 0.090λc SiO ₂ (refractive index 1.46) to optical thickness 0.100λc second layer TiO ₂ (refractive index 2.20 to 2.30) Optical thickness 0.510λc Third layer SiO ₂ (refractive index 1.46) is converted to optical thickness 0.2
The layers were laminated so as to have a thickness of 50λc. The second layer of TiO ₂ is Ti ₃ O ₅
Was formed by ion beam assisted vapor deposition in which an oxygen ion beam accelerated by an ion gun provided in the chamber was simultaneously irradiated while evaporating by electron beam heating. The initial ion current density during film formation is 30 μA /
cm ² , and the acceleration current was sequentially reduced to 10 μA / cm ² at the end. The acceleration voltage was constant at 500V. The temperature at the end of the deposition of the second layer was 71 ° C., and no deformation of the lens substrate was observed. The first layer, the second layer, and the third layer correspond to the intermediate refractive index layer, the high refractive index layer, and the low refractive index layer of the present invention, respectively. The spectral reflectance characteristics of the antireflection film of this embodiment
This is shown in the figure by a solid line. An excellent antireflection performance exhibiting a blue-violet interference color with a luminous reflectance on one side of 0.2% or less was obtained. The luminous reflectance referred to here is a ratio of the reflected light flux intensity to the incident light flux intensity in the entire visible region, and is weighted with the visibility.

(Example 2) An antireflection film was formed in the same manner as in Example 1 except that a lens made of a sulfur-containing urethane resin having a refractive index of 1.60 had the following film configuration. The wavelength λc, which is the center of the design, is set to 520 nm, and the first layer SiO ₂ (refractive index: 1.46) is coated from the substrate side with an optical film thickness of 0.1.
05λc TiO ₂ (refractive index 2.30) to optical thickness 0.080λc SiO ₂ (refractive index 1.46) to optical thickness 0.105λc second layer TiO ₂ (refractive index 2.20 to 2.30) Optical thickness 0.520λc Third layer SiO ₂ (refractive index 1.46) is converted to optical thickness 0.2
The layers were laminated so as to obtain 50λc. The temperature at the end of the deposition of the second layer is 7
The temperature was 2 ° C., and no deformation of the lens substrate was observed. An excellent antireflection performance exhibiting a blue-violet interference color with a luminous reflectance on one side of 0.2% or less was obtained.

(Embodiment 3) CR having a refractive index of 1.50
An anti-reflection film was formed in the same manner as in Example 1 except that the −39 resin lens had the following film configuration. The wavelength λc, which is the center of the design, is set to 520 nm, and the first layer SiO ₂ (refractive index: 1.46) is coated from the substrate side with an optical film thickness of 0.1.
30 λc TiO ₂ (refractive index 2.30) to optical thickness 0.070 λc SiO ₂ (refractive index 1.46) to optical thickness 0.100 λc second layer TiO ₂ (refractive index 2.20 to 2.30) Optical thickness 0.520λc Third layer SiO ₂ (refractive index 1.46) is converted to optical thickness 0.2
The layers were laminated so as to have a thickness of 50λc. The temperature at the end of the deposition of the second layer is 7
The temperature was 2 ° C., and no deformation of the lens substrate was observed. An excellent antireflection performance exhibiting a blue-violet interference color with a luminous reflectance on one side of 0.2% or less was obtained.

Example 4 A lens made of a sulfur-containing urethane resin having a refractive index of 1.66 was pretreated in the same manner as in Example 1,
An antireflection film was formed as a film configuration shown below. The wavelength λc, which is the center of the design, is set to 520 nm, and the first layer SiO ₂ (refractive index: 1.46) is coated from the substrate side with an optical film thickness of 0.1.
00λc TiO ₂ (refractive index 2.30) to optical thickness 0.090λc SiO ₂ (refractive index 1.46) to optical thickness 0.100λc second layer TiO ₂ (refractive index 2.18 to 2.35) Optical thickness 0.510λc Third layer SiO ₂ (refractive index 1.46) is converted to optical thickness 0.2
The layers were laminated so as to have a thickness of 50λc. The TiO _{2 of} the second layer is Ti ₃ O
₅ was prepared by ion beam assisted vapor deposition, in which the ₅ was vaporized by electron beam heating and simultaneously irradiated with an oxygen ion beam accelerated by an ion gun provided in the chamber. The ion accelerating voltage and the accelerating current during the film formation were set to 700 V and 30 μA / cm ² at the start, and ² V at the end.
The voltage was sequentially reduced to 00 V and 10 μA / cm ² . The temperature at the end of the deposition of the second layer was 69 ° C., and no deformation of the lens substrate was observed. An excellent antireflection performance exhibiting a blue-violet interference color with a luminous reflectance on one side of 0.2% or less was obtained.

Comparative Example 1 A lens made of a sulfur-containing urethane resin having a refractive index of 1.66 was treated in the same manner as in Example 1, and an antireflection film was formed in the following film configuration. The wavelength λc, which is the center of the design, is set to 520 nm, and the first layer SiO ₂ (refractive index: 1.46) is coated from the substrate side with an optical film thickness of 0.1.
00λc TiO ₂ (refractive index 2.30) to optical thickness 0.090λc SiO ₂ (refractive index 1.46) to optical thickness 0.100λc Second layer TiO ₂ (refractive index 2.30) to optical thickness 0 .5
20λc Third layer SiO ₂ (refractive index: 1.46) with an optical film thickness of 0.2
The layers were laminated so as to have a thickness of 50λc. The second layer of TiO ₂ is Ti ₃ O ₅
Was formed by ion beam assisted vapor deposition in which an oxygen ion beam accelerated by an ion gun provided in the chamber was simultaneously irradiated while evaporating by electron beam heating. Ion acceleration voltage and current density during film formation are 500
V was set constant at 30 μA / cm ² .

The temperature at the end of the deposition of the second layer was 81 ° C., and deformation of the lens substrate was observed. The spectral reflectance characteristics of the antireflection film of this comparative example are shown by broken lines in FIG. The luminous reflectance on one side was about 0.3%, the wavelength band of low reflection was narrower than that of Example 1, and the interference color was blue-purple with strong reddish color.

Comparative Example 2 A sulfur-containing urethane resin lens having a refractive index of 1.60 was treated in the same manner as in Example 1, and an antireflection film was formed in the following film configuration. The wavelength λc, which is the center of the design, is set to 520 nm, and the first layer SiO ₂ (refractive index: 1.46) is coated from the substrate side with an optical film thickness of 0.1.
05λc Second layer TiO ₂ (refractive index: 2.30) with an optical film thickness of 0.0
80λc Third layer SiO ₂ (refractive index: 1.46) with an optical film thickness of 0.1
05λc fourth layer TiO ₂ (refractive index: 2.30) with an optical film thickness of 0.5
20λc Fifth layer SiO ₂ (refractive index: 1.46) with an optical film thickness of 0.2
The layers were laminated so as to have a thickness of 50λc. The second layer was formed in the same manner as in Comparative Example 2. The temperature at the end of the deposition of the second layer is 81 ° C.,
Deformation of the lens substrate was observed. The luminous reflectance of one side was about 0.3%, the wavelength band of low reflection was narrower than that of Example 2, and the interference color was blue-purple with strong reddish color.

The antireflection films prepared in Examples 1, 2, 3, and 4 are excellent in adhesion to a substrate, weather resistance, moisture resistance, chemical resistance, and abrasion resistance. It was equivalent to 2.

[0032]

According to the present invention, it can be produced by vacuum deposition at a low temperature, and has a wide wavelength range in which the reflectance is low as compared with the case where the spectral reflectance has a positive inhomogeneity or the case where there is no inhomogeneity. In addition, since the heating by the ion beam during the film formation is suppressed, the temperature rise of the substrate is also reduced.
It is possible to easily apply a strong antireflection film to the synthetic resin lens.

The anti-reflection film has good adhesion to the substrate,
It has excellent weather resistance, moisture resistance, chemical resistance, and abrasion resistance, and is suitable for applications such as spectacle lenses and camera lenses.

[Brief description of the drawings]

FIG. 1 is a diagram showing spectral reflectance characteristics of antireflection films of Example 1 and Comparative Example 1.

FIG. 2 is a diagram showing a change in the refractive index in the thickness direction of a high refractive index layer of Example 1.

Claims (6)

[Claims] 1. A QHQ type antireflection film in which an intermediate refractive index layer, a high refractive index layer, and a low refractive index layer are laminated in this order on a lens substrate made of a synthetic resin. In the synthetic resin lens provided with an antireflection film, the high refractive index layer has a wavelength (hereinafter referred to as “λ
c ". Characterized in that the refractive index in (1) changes along the film thickness direction so as to be lower by 0.01 to 0.20 on the surface side than on the lens substrate side. lens. 2. The synthetic resin lens with an antireflection film according to claim 1, wherein the high refractive index layer is made of TiO ₂ or 20 wt% of TiO ₂ .
%, The balance being ZrO ₂ , Ta ₂ O ₅ or an oxide of a rare earth element. 3. The synthetic resin lens with an anti-reflection film according to claim 2, wherein the high refractive index layer is a high refractive index layer formed by oxygen ion beam assisted vapor deposition and outputs an ion beam. Alternatively, a synthetic resin lens provided with an antireflection film, wherein the high refractive index layer has a refractive index change in a film thickness direction by changing an amount of introduced gas during a film forming process. 4. The synthetic resin lens with an anti-reflection film according to claim 1, wherein the lens substrate has a refractive index at λc of 1.50 or more, and the intermediate refractive index layer is The equivalent refractive index at λc is 1.
60-1.90, the optical thickness of which is 0.22λc-0.3
2λc, and the high refractive index layer has an equivalent refractive index of 2.0 at λc.
0 to 2.30, and the optical film thickness is 0.45λc to 0.55
λc, and the low refractive index layer has an equivalent refractive index at λc of 1.43-1.47 and an optical thickness of 0.22.
λc to 0.28λc, wherein the synthetic resin lens is provided with an antireflection film. 5. The synthetic resin lens with an antireflection film according to claim 1, wherein the intermediate refractive index layer has a refractive index at λc of 1.43 to 1.47 and an optical thickness of the intermediate refractive index layer. A low-refractive-index material layer having a refractive index at 0.08λc to 0.13λc, a high-refractive-index material layer having a refractive index at λc of 2.00 to 2.30 and an optical thickness of 0.06λc to 0.11λc;
And a low-refractive-index material layer having a refractive index of 1.43 to 1.47 at λc and an optical thickness of 0.08 λc to 0.13 λc, which are sequentially laminated. Synthetic resin lens with anti-reflective coating. 6. The synthetic resin lens with an antireflection film according to claim 1, wherein the low refractive index layer is made of SiO ₂ .