WO2019049471A1

WO2019049471A1 - Lens

Info

Publication number: WO2019049471A1
Application number: PCT/JP2018/023981
Authority: WO
Inventors: 光恵吉田; 陽明江口
Original assignee: 日本電産株式会社
Priority date: 2017-09-06
Filing date: 2018-06-25
Publication date: 2019-03-14
Also published as: CN111133342A

Abstract

A lens according to one embodiment of the present invention is provided with: a lens main body that contains a polymer material; and an inorganic film that is formed on the surface of the lens main body. The polymer material has a water absorption rate of more than 0% by mass but 0.05% by mass or less. The inorganic film has a Vickers hardness of 600 HV or more.

Description

lens

The present invention relates to a lens.

As a material of an optical member such as a lens, a polymeric material having light transparency is known. When a polymer material is used, it is possible to mold a large amount of lenses by molding using a mold. Further, since the polymer material has a specific gravity lower than that of an inorganic material such as glass, it is possible to reduce the weight of the entire apparatus including the lens.

As such a lens (hereinafter sometimes referred to as "plastic lens") having a polymer material as a forming material, a configuration is known in which a dielectric multilayer film made of an inorganic material is provided on the surface to prevent reflection. There is. Further, as a plastic lens, there is known a configuration in which a hard coat film (inorganic film) is formed on the light transmission surface of the lens in order to suppress the damage of the lens surface.

In recent years, the application of the above-mentioned plastic lens is spreading. For example, when a plastic lens is applied to an in-vehicle imaging device, the weight of the device can be reduced, which is preferable. On the other hand, an on-vehicle imaging device is exposed to a high temperature environment when installed in a vehicle, and is exposed to a high humidity environment when installed outside a vehicle. Therefore, the plastic lens used for such a device is required to have a durability to withstand a severe use environment such as high temperature and high humidity.

However, there is a large difference in thermal expansion coefficient between the polymer material constituting the lens and the inorganic material constituting the dielectric multilayer film and the like. Therefore, with a plastic lens having an inorganic film on the surface, the inorganic film may be damaged by thermal stress.

Further, the polymer material constituting the lens has a large water absorption rate as compared with an inorganic material such as glass. Therefore, when the plastic lens absorbs water, stress is applied to the inorganic film due to volumetric expansion of the lens, and the inorganic film may be broken.

In order to solve such problems, there is known a lens having a configuration in which an intermediate layer for relieving stress is provided between a plastic lens and an inorganic film such as a dielectric multilayer film to suppress breakage of the inorganic film ( For example, refer to Patent Document 1).

Unexamined-Japanese-Patent No. 2010-72451

However, when the above configuration is adopted, equipment for forming the intermediate layer is required in the lens manufacturing process. In addition, the number of processes for forming the intermediate layer is increased, and the production efficiency is reduced. Therefore, the lens which can suppress the failure | damage of an inorganic membrane was provided without providing an intermediate | middle layer.

The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a lens exhibiting high durability in a high temperature and high humidity environment without forming an intermediate layer.

According to a first aspect of the present invention, a lens main body containing a polymer material, and an inorganic film formed on the surface of the lens main body, wherein the polymer material has a water absorption rate higher than 0% by mass The inorganic film provides a lens having a Vickers hardness of 600 HV or more.

According to a second aspect of the present invention, a lens main body containing a polymer material, and an inorganic film formed on the surface of the lens main body, wherein the polymer material has a water absorption rate of 0.05% by mass The inorganic film provides a lens having a Vickers hardness of 600 HV or more.

According to a third aspect of the present invention, a lens main body containing a polymer material and an inorganic film formed on the surface of the lens main body are provided, and the polymer material has a water absorption rate of 0.1 mass%. The inorganic film provides a lens having a Vickers hardness of 800 HV or more.

According to a fourth aspect of the present invention, a lens main body containing a polymer material, and an inorganic film formed on the surface of the lens main body, wherein the polymer material has a water absorption coefficient of 0.15% by mass The inorganic film provides a lens having a Vickers hardness of 850 HV or more.

According to the present invention, it is possible to provide a lens that exhibits high durability in a high temperature and high humidity environment.

FIG. 1 is a schematic view showing a lens of the embodiment. FIG. 2 is a schematic view of the lens 1 when the inorganic film 20 is a dielectric multilayer film. FIG. 3 is a scatter diagram showing the results of the example.

[Lens] Hereinafter, a lens according to a first embodiment of the present invention will be described with reference to FIGS. In addition, in all the following drawings, in order to make a drawing intelligible, the dimension, the ratio, etc. of each component are suitably varied.

FIG. 1 is a schematic view showing a lens of the present embodiment. As shown in the figure, the lens 1 of the present embodiment includes a lens body 10 and an inorganic film 20. The lens 1 shown in the figure is suitably used, for example, as the second and subsequent lenses counted from the object side in a lens optical system in which a plurality of lenses are combined.

(Lens Body) The lens body 10 is a molded body containing a polymer material. A thermoplastic resin can be used for the polymeric material which is the formation material of the lens main body 10. Specifically, as a polymer material which is a forming material of the lens body 10, thermoplastic resins such as polycarbonate (PC), cyclic olefin polymer (COP), cyclic olefin copolymer (COC) and the like can be used.

In addition, the polymer material may be used in combination with various additives such as a stabilizer, an antioxidant, a filler, and a refractive index regulator as long as the light transmittance of the lens body 10 is not impaired.

The lens body 10 has one surface S1 viewed along the optical axis L of the lens body 10, the other surface S2 opposite to the one surface S1, and one surface S1 extending in the circumferential direction of the lens body 10 And a circumferential surface S3 intersecting and intersecting with the other surface S2.

One surface S1 includes a concave surface Sa which is visible along the optical axis L and overlaps the optical axis L, and a flat surface Sb which is disposed around the concave surface Sa and is continuous with the concave surface Sa. The concave surface Sa is a light transmission surface. The concave surface Sa is formed in a circular shape centered on the position of the optical axis L in a field of view when viewing one surface S1 along the optical axis L of the lens body 10.

Further, in the lens body 10, the other surface S2 is a convex surface. The other surface S2 is a light transmitting surface.

The lens body 10 is a so-called meniscus lens. The lens main body 10 is designed to have a larger curvature of the concave surface Sa than the curvature of the other surface S2, and has negative power.

(Inorganic Film) The inorganic film 20 is provided on the entire surface of the other surface S2 of the lens body 10. In the lens 1 shown in the figure, examples of the inorganic film 20 include a dielectric multilayer film that functions as an antireflective film, and a hard coat film that functions as a film that prevents the lens body 10 from being scratched.

FIG. 2 is a schematic view of the lens 1 when the inorganic film 20 is a dielectric multilayer film. When the inorganic film 20 is a dielectric multilayer film, the inorganic film 20 can be obtained by depositing two inorganic materials having different refractive indexes alternately via a mask. Such an inorganic film 20 provides the lens 1 with an antireflection function.

The inorganic film 20 is, for example, a laminate in which a first film 21 containing SiO ₂ and a second film 22 having a higher refractive index than the first film 21 are alternately stacked. Specifically, the first film 21 contains SiO ₂ (refractive index: 1.46) and Al ₂ O ₃ (refractive index: 1.77). The compounding ratio of SiO ₂ and Al ₂ O ₃ in the vapor deposition source may be determined according to the design of the refractive index of the first film 21.

The second film 22 contains, for example, Ta ₂ O ₅ (refractive index: 2.16) and TiO ₂ (refractive index: 2.49). The compounding ratio of Ta ₂ O ₅ and TiO ₂ in the evaporation source may be determined according to the design of the refractive index of the second film 22.

The inorganic film 20 shown in the figure is shown as having a structure in which the first film 21 and the second film 22 are alternately laminated in a total of seven layers.

As a result of various investigations by the inventor of the lens having the above-mentioned configuration, it is high temperature as long as the water absorption of the polymer material constituting the lens main body 10 and the hardness of the inorganic film are respectively defined in predetermined ranges. The inventors have found that they exhibit high durability in a high humidity environment, and completed the invention.

First, in the lens of the first aspect, the water absorption rate of the polymer material constituting the lens body 10 is higher than 0% by mass and 0.05% by mass or less. In such a lens, the Vickers hardness of the inorganic film 20 is 600 HV or more.

In the lens of the second aspect, the water absorption rate of the polymer material constituting the lens body 10 is higher than 0.05% by mass and 0.1% by mass or less. In such a lens, the Vickers hardness of the inorganic film 20 is 600 HV or more.

In the lens of the second aspect, the Vickers hardness of the inorganic film 20 is preferably 800 HV or more.

In the lens of the third aspect, the water absorption rate of the polymer material constituting the lens body 10 is higher than 0.11% by mass and 0.15% by mass or less. In such a lens, the Vickers hardness of the inorganic film 20 is 800 HV or more.

In the lens of the third aspect, the Vickers hardness of the inorganic film 20 is preferably 900 HV or more.

In the lens of the fourth aspect, the water absorption rate of the polymer material constituting the lens body 10 is higher than 0.15 mass% and 0.2 mass% or less. In such a lens, a lens in which the Vickers hardness of the inorganic film 20 is 850 HV or more can be mentioned.

In the present specification, the water absorption rate of the polymer material is a value measured according to the method defined in JIS K7209.

Moreover, in this specification, according to the nanoindentation method prescribed | regulated to ISO14577, the Vickers hardness uses the value which converted the measurement result measured on the following test conditions into Vickers hardness. (Test conditions) Test force: 0.4 mN Test force arrival time: 10 seconds Test force holding time: 0 seconds Test force unloading time: 10 seconds Working indenter: Vickers indenter

The water absorption rate of the polymer material depends on the physical properties of the polymer material used. Further, the Vickers hardness of the inorganic film 20 depends on the composition of the inorganic film 20 and the film forming conditions at the time of forming the inorganic film 20.

For example, when the inorganic film 20 is a deposited film obtained by ion-assisted vapor deposition of an inorganic material, the Vickers hardness of the inorganic film 20 can be adjusted as follows.

First, when the inorganic material used as a deposition source is changed to an inorganic material having a relatively high hardness as compared with the original inorganic material, the Vickers hardness of the obtained inorganic film becomes high. In addition, when the deposition temperature is relatively lowered compared to the time of manufacturing the above-mentioned inorganic film, the Vickers hardness of the obtained inorganic film tends to be high. In addition, when the assist conditions (ion acceleration voltage, ion acceleration current) are relatively increased as compared with the production of the inorganic film, the Vickers hardness of the obtained inorganic film tends to be high.

In the present embodiment, by appropriately changing the type of the polymer material that is the forming material of the lens main body 10 as described above, the type of the inorganic material that is the forming material of the inorganic film 20, and the film forming conditions of the inorganic film 20 The lens according to any one of the first to fourth aspects can be used.

According to the lens having the above configuration, a lens exhibiting high durability in a high temperature and high humidity environment without providing an intermediate layer for buffering stress between the lens body 10 and the inorganic film 20 is provided. can do.

Although the preferred embodiments according to the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such examples. The shapes, combinations, and the like of the constituent members shown in the above-described example are merely examples, and various changes can be made based on design requirements and the like without departing from the spirit of the present invention.

EXAMPLES The present invention will be described by way of examples, but the present invention is not limited to these examples.

In this example, a dielectric multilayer film (inorganic film) is formed on the surface of a substrate (φ3 cm × 0.1 cm) made of a polymer material to form a test piece, and the obtained test piece The durability under high temperature and high humidity environment was evaluated. The obtained test piece is a model sample of a lens in which an inorganic film is formed on a plastic lens.

The polymeric materials used for the test pieces were as follows. Polymeric material 1: COP1 (Tg: 138 ° C., water absorption: <0.01% by mass) Polymeric material 2: COP2 (Tg: 164 ° C., water absorption: 0.17% by mass) Polymeric material 3: COC (COC) Tg: 153 ° C., water absorption: 0.01% by mass Polymer material 4: PC 1 (Tg: 145 ° C., water absorption: 0.07% by mass) Polymer material 5: PC 2 (Tg: 156 ° C., water absorption: 0.12 mass%)

COP shows a cyclic olefin polymer, COC shows a cyclic olefin copolymer, PC shows a polycarbonate, respectively.

The polymeric material 1 and the polymeric material 3 are included in the range of “the water absorption coefficient is higher than 0% by mass and 0.05% by mass or less” defined in the present invention. The polymeric material 4 is included in the range of “the water absorption coefficient is higher than 0.05% by mass and 0.1% by mass or less” defined in the present invention. The polymeric material 5 is included in the range of “the water absorption coefficient is higher than 0.1% by mass and 0.15% by mass or less” defined in the present invention. The polymer material 2 is included in the range of “water absorption coefficient is higher than 0.15 mass% and 0.2 mass% or less” defined in the present invention.

Moreover, the inorganic material used for preparation of an inorganic membrane was as follows. (Low refractive index material) Inorganic material 1: SiO ₂ inorganic material 2: SiO ₂ + Al ₂ O ₃ (SiO ₂ : Al ₂ O ₃ = 97: 3) Inorganic material 3: SiO ₂ + Al ₂ O ₃ (SiO ₂ : Al) ₂ O ₃ = 93: 7)

(High refractive index material) Inorganic material 4: Ta ₂ O ₅ + TiO ₂ (Ta ₂ O ₅ : TiO ₂ = 4: 1)

The dielectric multilayer film is formed by depositing a film of a low refractive material (the first film described above) on a substrate, and depositing a film of the high refractive material (the second film described above) and the first film alternately in order It formed. In each test piece, a laminated film of 7 layers in total including 4 layers of the first film and 3 layers of the second film was produced as a dielectric multilayer film. Each film thickness and total film thickness of the first film and the second film of the manufactured dielectric multilayer film were made constant in each test piece by adjusting the film forming conditions. The total film thickness of the dielectric multilayer film was 300 nm.

In addition, when forming the dielectric multilayer film, the deposition temperature and the assist condition were changed to form dielectric multilayer films having different Vickers hardness. Condition 1: Deposition temperature-first set temperature, assist condition-first ion acceleration voltage Condition 2: deposition temperature-first set temperature, assist condition-second ion acceleration voltage Condition 3: deposition temperature-second Preset temperature, assist condition-first ion acceleration voltage condition 4: deposition temperature-second preset temperature, assist condition-second ion acceleration voltage ([first preset temperature] <[second preset temperature] And [first ion acceleration voltage] <[second ion acceleration voltage].) As described above, the first set temperature at which the deposition temperature is relatively lower is the second set temperature. The Vickers hardness of the resulting inorganic film tends to be higher than when the film is formed. In addition, the Vickers hardness of the obtained inorganic film tends to be higher in the case of the second ion acceleration voltage in which the assist condition is relatively stronger than in the case of forming the film at the first ion acceleration voltage.

(Evaluation) The prepared test piece was stored at a temperature of 85 ° C. and a humidity of 85%, and peeling of the inorganic film was observed every 1000 hours for up to 1000 hours. Each test piece was evaluated as follows according to the time to occurrence of peeling of the inorganic film. ◎: No film peeling after 1000 hours. ○: Confirming film peeling after 1000 hours. Fair: Peeling of film was confirmed after 500 hours. X: Confirming film peeling after 250 hours.

In the evaluation, “◎” is the best, and it is evaluated in the order of “o” and “Δ”, and “x” is the worst evaluation. In addition, “」 ”,“ ○ ”and“ Δ ”were respectively judged as non-defective products and“ x ”as defective products.

The evaluation results are shown in Tables 1 to 5 and FIG.

As a result of the evaluation, in the case of a substrate having the polymer material 1 or the polymer material 3 as a forming material, peeling of the inorganic film after storage under high temperature and high humidity conditions is suppressed by providing the inorganic film having a Vickers hardness of 600 HV or more. It was done.

Moreover, in the board | substrate which uses the polymeric material 4 as a forming material, peeling of the inorganic membrane after preserve | saving on high temperature and high humidity conditions was suppressed by providing the inorganic membrane which is 600 HV or more in Vickers hardness.

Furthermore, in the case of a substrate using the polymer material 4 as a forming material, peeling of the inorganic film after storage under high temperature and high humidity conditions can be more reliably suppressed by providing the inorganic film having a Vickers hardness of 800 HV or more. The

Moreover, in the board | substrate which uses the polymeric material 5 as a forming material, peeling of the inorganic membrane after preserve | saving on high temperature and high humidity conditions was suppressed by providing the inorganic membrane which is 800 HV or more in Vickers hardness.

Furthermore, in the case of a substrate using the polymer material 5 as a forming material, peeling of the inorganic film after storage under high temperature and high humidity conditions can be more reliably suppressed by providing the inorganic film having a Vickers hardness of 900 HV or more. The

Moreover, in the board | substrate which uses the polymeric material 2 as a forming material, peeling of the inorganic film after preserve | saved on high temperature and high humidity conditions was suppressed by providing the inorganic film which has Vickers hardness of 850 HV or more.

Based on the above results, even when the lens body is formed using each polymer material and the inorganic film produced in the present embodiment is formed on the surface of the lens body, durability under high temperature and high humidity conditions is obtained. The same tendency is considered for the sex.

From the above results, it was confirmed that the present invention is useful.

DESCRIPTION OF SYMBOLS 1 ... Lens, 10 ... Lens main body, 20 ... Inorganic film, 21 ... 1st film, 22 ... 2nd film, S1 ... One surface, S2 ... other surface

Claims

A lens main body including a polymer material, and an inorganic film formed on a surface of the lens main body, wherein the polymer material has a water absorption coefficient higher than 0% by mass and 0.05% by mass or less, The film is a lens having a Vickers hardness of 600 HV or more.
The inorganic film is a dielectric multilayer film, and in the dielectric multilayer film, a first film containing SiO 2 and a second film having a refractive index higher than that of the first film are alternately stacked. The lens according to claim 1, which is a laminate.
The lens according to claim 2 , wherein the first film contains SiO 2 and Al 2 O 3 .
The lens according to claim 2 , wherein the second film contains Ta 2 O 5 and TiO 2 .
A lens body containing a polymer material, and an inorganic film formed on the surface of the lens body, wherein the polymer material has a water absorption coefficient higher than 0.05% by mass and 0.1% by mass or less, The inorganic film is a lens having a Vickers hardness of 600 HV or more.
The lens according to claim 5, wherein the inorganic film has a Vickers hardness of 800 HV or more.
The inorganic film is a dielectric multilayer film, and in the dielectric multilayer film, a first film containing SiO 2 and a second film having a refractive index higher than that of the first film are alternately stacked. The lens according to claim 5, which is a laminate.
The lens according to claim 7, wherein the first film comprises SiO 2 and Al 2 O 3 .
The lens according to claim 7, wherein the second film contains Ta 2 O 5 and TiO 2 .
A lens body containing a polymer material, and an inorganic film formed on the surface of the lens body, wherein the polymer material has a water absorption coefficient higher than 0.1% by mass and 0.15% by mass or less, The inorganic film is a lens having a Vickers hardness of 800 HV or more.
The lens according to claim 10, wherein the inorganic film has a Vickers hardness of 900 HV or more.
The inorganic film is a dielectric multilayer film, and in the dielectric multilayer film, a first film containing SiO 2 and a second film having a refractive index higher than that of the first film are alternately stacked. The lens according to claim 10, which is a laminate.
The lens of claim 12, wherein the first film comprises SiO 2 and Al 2 O 3 .
The lens according to claim 12, wherein the second film contains Ta 2 O 5 and TiO 2 .
A lens body containing a polymer material, and an inorganic film formed on a surface of the lens body, wherein the polymer material has a water absorption coefficient higher than 0.15 mass% and 0.2 mass% or less, The inorganic film is a lens having a Vickers hardness of 850 HV or more.
The inorganic film is a dielectric multilayer film, and in the dielectric multilayer film, a first film containing SiO 2 and a second film having a refractive index higher than that of the first film are alternately stacked. The lens according to claim 15, which is a laminate.
The lens of claim 16, wherein the first film comprises SiO 2 and Al 2 O 3 .
The lens according to claim 16, wherein the second film contains Ta 2 O 5 and TiO 2 .