JPH07113682B2 - Lens that does not easily attach dirt - Google Patents

Description

TECHNICAL FIELD The present invention relates to a lens of a camera, glasses, or the like which is less likely to be stained.

[Conventional technology]

Lenses such as cameras and glasses are usually provided with a surface and / or an antireflection film.

[Problems to be solved by inventions / inventions]

For this antireflection film, a single layer or a multilayer structure of a thin film of an oxide such as TiO ₂ or SiO ₂ (for example, a thin film formed by vacuum deposition or sputtering) is often used. Since a hydrophilic surface is formed, the surface is contaminated. Therefore, there is a problem that, for example, water stains occur. Water bleeding is a phenomenon that marks like marks remain when water drops are dripped on the surface and dried.

[Means for solving problems]

In the present invention, in order to improve such a problem, the surface of the antireflection film is coated with a hard film mainly made of carbon.

[Action]

The carbonaceous hard film used in the present invention is formed by the plasma CVD method, the ion plating method, the ion beam method, and the sputtering method, and this film has the following properties.

When the thickness is 1 μm, Vickers hardness is 1000 or more. Mainly made of carbon and may contain hydrogen or fluorine. Amorphous or polycrystalline or a mixture of both (coated) The coated lens has a highly water repellent surface. Because
Drainage is prevented.

To obtain sufficient water and preventive effect, the contact angle between the surface and pure water should be
It was necessary to be at least 50 °.

If the carbon film becomes too thick, the antireflection effect of the antireflection film will be impaired, so the film thickness needs to be 200 Å or less, and preferably 100 Å or less.

The minimum required film thickness depends on the film forming conditions.
When the film thickness is gradually increased from 0 to make the hydrophilic surface water repellent, that is, the film thickness at which the contact angle with pure water is 50 ° or more is the minimum required film thickness.

〔Example〕

FIG. 1 is a conceptual diagram showing a vertical cross section of a spectacle lens according to this example. A CR-39 plastic lens 1, a hard polysiloxane hard coat layer 2 for covering the same, and an antireflection film formed thereon. A film 3 and a "hard thin film (carbonaceous film) 4 mainly composed of carbon" 4 formed thereon.

FIG. 2 shows a plasma CVD apparatus used to form the carbonaceous film 4.

An electrode 6 is attached to a chamber 5 that can be evacuated to a vacuum, and a "hard coat layer 2 and an antireflection film 3" are formed on the electrode 6.
The formed lens 7 "is placed. The electrode 6 is configured so that cooling water 8 can flow inside, and the side surface and the back surface are covered with an insulator 9. A reaction gas is introduced from the flow rate control valve 14 and electric power is supplied from the RF power source 11 to generate plasma and form a film.

The film forming conditions are shown in Table 1.

The carbonaceous film 4 thus formed had a thickness of about 50Å, and the contact angle with pure water after film formation was about 88 °.

The structure of the antireflection film 3 used is shown in FIG.

[Comparative example]

The carbonaceous film 4 is excluded from the lens of the above embodiment, and its vertical section is shown in FIG.

[Test example]

Water droplets were dropped on the lenses of the example and the comparative example to compare the degree of occurrence of water blush. In the comparative example, 90% of the lenses produced water blush, but in the example, it was 0%.

When the above film was analyzed by SIMS (secondary ion mass spectrometry), C, F, H, Si and O were detected. Also, of these,
Since Si and O use silicon oxide as the uppermost layer of the antireflection film, Si and O from the base were also detected.

〔The invention's effect〕

As described above, according to the present invention, since a water-repellent surface can be obtained, there is an effect of preventing water stain. Also, an antifogging effect can be expected.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a vertical cross section of a lens according to an example of the present invention. FIG. 2 is a conceptual diagram illustrating the configuration of the plasma CVD apparatus used to form the carbonaceous film 4 in the examples. FIG. 3 is a conceptual diagram showing a vertical sectional structure of the antireflection film 3 used in the lens of the example. FIG. 4 is a conceptual diagram showing a vertical section of a conventional lens. [Explanation of symbols of main parts] 1 ... CR-39 plastic lens 2 ... hard coat layer 3 ... antireflection film 4 ... hard film mainly made of carbon 5 ... vacuum chamber 6 ... electrode 7 ... lens 8 …… Cooling water 9 …… Insulator 10 …… Matching circuit 11 …… RF power supply (13.56MHz) 12 …… CH ₄ gas 13 …… CF ₄ gas 14 …… Flow control valve

Claims (1)

[Claims] 1. A lens having an antireflection film, comprising a water stain prevention layer on the antireflection film, wherein the water stain prevention layer is a hard carbon thin film containing hydrogen and fluorine. A lens whose surface has a contact angle with pure water of 50 degrees or more and is unlikely to adhere to dirt.