阅读说明：本技术 防尘透镜及其制造方法 (Dust-proof lens and manufacturing method thereof ) 是由 川岸秀一朗 白石幸一郎 于 2018-04-27 设计创作，主要内容包括：本发明的目的在于提供透明性不会受损且防尘性能得以提高的防尘透镜及其制造方法。防尘透镜的特征在于,在玻璃透镜的表面上至少形成有导电性膜,所述导电性膜通过由TiO<Sub>2</Sub>以及Ti<Sub>3</Sub>O<Sub>5</Sub>中的至少一个形成的氧化钛的单层或者含有50％以上的所述氧化钛的混合层形成,所述导电性膜的膜厚为1nm以上,所述导电性膜的面内方向的结晶粒径为200nm以上。(The invention aims to provide a dustproof lens and a manufacturing method thereof, wherein the transparency of the dustproof lens is not damaged and the dustproof performance is improved. The dustproof lens is characterized in that at least a conductive film is formed on the surface of the glass lens, and the conductive film is formed by TiO 2 And Ti 3 O 5 At least one layer of titanium oxide or a mixed layer containing 50% or more of the titanium oxide, wherein the thickness of the conductive film is 1nm or more, and the conductive filmHas a crystal grain diameter of 200nm or more in the in-plane direction.)

1. A dust-proof lens is characterized in that,

at least a conductive film is formed on the surface of the glass lens,

the conductive film is made of TiO₂And Ti₃O₅A single layer of titanium oxide or a mixed layer containing 50% or more of the titanium oxide,

the thickness of the conductive film is 1nm or more,

the crystalline grain diameter of the in-plane direction of the conductive film is 200nm or more.

2. The dust-proof lens according to claim 1, wherein a single-layer film of the conductive film is formed on a surface of the glass lens.

3. The dust-proof lens according to claim 1,

an antireflection film including the conductive film is formed on a surface of the glass lens,

the outermost layer of the antireflection film is formed of a low refractive index film having a lower refractive index than the glass lens.

4. The dust-proof lens according to any one of claims 1 to 3, wherein a surface resistance of a film formed on the surface of the glass lens is 10¹³(omega/port) or less.

5. A method for manufacturing a dustproof lens is characterized in that,

comprises a step of forming at least a conductive film on the surface of a glass lens,

in the step of forming the conductive film, TiO is formed so that the film thickness is 1nm or more and the crystal grain size in the in-plane direction is 200nm or more₂And Ti₃O₅A single layer of titanium oxide or a mixed layer containing 50% or more of the titanium oxide.

6. The method of manufacturing a dust-proof lens according to claim 5, wherein a substrate heating temperature at which the conductive film is formed by a vapor deposition method is 250 ℃ or higher.

7. The method for manufacturing a dust-proof lens according to claim 5 or 6, wherein the thickness is 5.0 x 10^{- 3}Introducing oxygen gas at a pressure of Pa or higher when the conductive film is formed.

Technical Field

The invention relates to a dustproof lens and a manufacturing method thereof.

Background

In general, optical glass is easily charged due to its high resistivity. Therefore, there are problems as follows: dust is easily attached to the surface of the lens using the optical glass. Charged dust is difficult to remove when adhering to the lens surface, and adversely affects an image formed by an optical system using the lens.

The following patent documents disclose an optical member having antistatic performance, which is formed by forming a titanium oxide film having an insufficient equivalent on the surface of a substrate.

Disclosure of Invention

Technical problem to be solved by the invention

However, as shown in patent document 1, if titanium oxide is deficient in oxygen, the titanium oxide film is close to metal. Therefore, there is a problem that the light transmittance of the film is lowered and the transparency is impaired.

The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a dust-proof lens having improved dust-proof performance without impairing transparency, and a method for manufacturing the same.

Technical solution for solving technical problem

The dustproof lens of the present invention is characterized in that at least a conductive film is formed on the surface of the glass lens, and the conductive film is formed of TiO₂And Ti₃O₅A single layer of titanium oxide or a mixed layer containing 50% or more of the titanium oxide, and the conductive filmThe film thickness is 1nm or more, and the crystal grain size of the conductive film in the in-plane direction is 200nm or more.

In the present invention, a single layer film of the conductive film may be formed on the surface of the glass lens.

In the present invention, it is preferable that an antireflection film including the conductive film is formed on a surface of the glass lens, and an outermost layer of the antireflection film is formed of a low refractive index film having a lower refractive index than the glass lens.

In the present invention, it is preferable that the surface resistance of the film formed on the surface of the glass lens is 10¹³(omega/port) or less.

The method for manufacturing a dust-proof lens of the present invention includes a step of forming at least a conductive film on a surface of a glass lens, and in the step of forming the conductive film, TiO is formed so that a film thickness of 1nm or more and a crystal grain size in an in-plane direction is 200nm or more₂And Ti₃O₅A single layer of titanium oxide or a mixed layer containing 50% or more of the titanium oxide.

In the present invention, it is preferable that the substrate heating temperature at the time of forming the conductive film by the vapor deposition method is 250 ℃.

In the present invention, it is preferable that the concentration is 5.0X 10^-3Introducing oxygen gas at a pressure of Pa or higher when the conductive film is formed.

(Effect of the invention)

According to the present invention, a dust-proof lens and a method for manufacturing the same, in which the transparency is not impaired and the dust-proof performance is improved, can be provided.

Drawings

Fig. 1 is a schematic view of the dust-proof lens of the present embodiment.

Fig. 2 is a partially enlarged schematic view of the dust-proof lens of the first embodiment.

Fig. 3 is a partially enlarged schematic view of a dust-proof lens of the second embodiment.

Fig. 4 is an SEM picture of example 1.

Fig. 5 is a partial schematic view of fig. 4.

Fig. 6 is an SEM picture of comparative example 1.

Fig. 7 is a partial schematic view of fig. 6.

Detailed Description

Hereinafter, a mode for carrying out the present invention (hereinafter, simply referred to as "the present embodiment") will be described in detail.

In the related art, a technique for improving the antistatic performance by making a titanium oxide film formed on the surface of a substrate lack oxygen is known. However, the lack of oxygen makes the film close to metal, impairing its transparency, and unsuitable for use as an optical film.

Under such a background, the present inventors have developed a film having excellent conductivity without impairing transparency (transmission performance). That is, the dust-proof glass in the present embodiment has the following characteristic portions.

(1) At least a conductive film is formed on the surface of the glass lens.

(2) The conductive film is made of TiO₂And Ti₃O₅A single layer of titanium oxide or a mixed layer containing 50% or more of the titanium oxide.

(3) The thickness of the conductive film is 1nm or more.

(4) The crystalline grain diameter of the conductive film in the in-plane direction is 200nm or more.

Fig. 1 is a schematic view of the dust-proof lens of the present embodiment. The dust-proof lens 1 shown in fig. 1 is constituted with: a glass lens 2 as a substrate, and a conductive film 3 formed on the surface of the glass lens 2 on the light incident side.

The glass lens 2 is not particularly limited, and is, for example, a glass lens for a monitoring camera, a vehicle-mounted camera, or a projector. The surface of the glass lens 2 on which the conductive film 3 is formed is, for example, aspherical. The glass lens 2 in fig. 1 is, for example, a meniscus lens having negative refractive power, but may be a meniscus lens having positive refractive power, or two convex lenses, two concave lenses, or the like. The surface of the glass lens 2 may be a shape other than an aspherical surface.

The conductive film 3 and the antireflection film 4 formed on the surface of the glass lens 2 will be described in detail below.

< first embodiment >

In the first embodiment shown in fig. 2, a single-layer film of the conductive film 3 is formed on the surface of the glass lens 2. In fig. 2, the conductive film 3 is formed directly on the surface of the glass lens 2, and is composed of only the glass lens 2 and the conductive film 3. However, the first embodiment also includes a configuration in which an undercoat layer (not shown) for improving the adhesion or crystallinity of the conductive film 3 is interposed between the conductive film 3 and the glass lens 2.

As described in (2) above, the conductive film 3 is made of TiO₂(titanium dioxide) and Ti₃O₅A single layer of titanium oxide formed of at least one of (titanium pentoxide) or a mixed layer containing 50% or more of the titanium oxide.

The titanium oxide is made of TiO₂And Ti₃O₅Is represented by the formula (II) TiO₂And Ti₃O₅In the present embodiment, titanium oxide having a stoichiometric composition free from oxygen is defined. The conductive film 3 preferably contains at least TiO₂。Ti₃O₅Can be used as film-forming TiO₂The starting material of (2), and Ti may be added₃O₅All converted to TiO₂The film may be formed (phase-changed) in a state where a part of Ti remains in the film₃O₅. The composition of titanium oxide can be analyzed by an existing method, and for example, it can be measured by a spectrophotometer. In addition, titanium oxide constituting the conductive film 3 is not limited to TiO₂Single phase, and TiO₂And Ti₃O₅In addition to the mixed phases of (3), may also be composed of Ti₃O₅The single phase composition of (3).

The conductive film 3 may be a mixed layer containing 50% or more and less than 100% of titanium oxide, or may be a single layer containing 100% of titanium oxide. The mixed layer may be a mixture of metal oxides other than titanium oxide, or may be a mixture of a semiconductor material, an electrically conductive material, and other materials other than titanium oxideAnd an insulating material. In addition, as for the material other than titanium oxide contained in the conductive film 3, a material capable of improving conductivity while maintaining transparency in a mixed layer with titanium oxide is required. As a material other than titanium oxide, SiO can be used₂、Ta₂O₅、Nb₂O₅、ZrO₂、Al₂O₃、MgF₂Etc. are generally used as vapor deposition materials.

When the conductive film 3 is formed of a mixed layer, it preferably contains 80% or more of titanium oxide.

In the present embodiment, "%" as a content is "% by mass".

As described in (3) above, the thickness of the conductive film 3 is 1nm or more. In the present embodiment, the upper limit of the film thickness of the conductive film 3 is not limited. However, the upper limit of the film thickness is preferably about 500nm or less. The film thickness can be measured, for example, by using a longitudinal cross-sectional TEM image (TEM image obtained by cutting along the film thickness direction and observing the cut surface). In the present embodiment, the film thickness of the conductive film 3 is controlled within the above range, and even when measurement errors or variations occur due to measurement conditions or the like, for example, by satisfying desired conductivity (surface resistance) while maintaining transparency, it is possible to estimate a configuration including the configuration of the present embodiment.

The thickness of the conductive film 3 is preferably 5nm or more, more preferably 10nm or more, and further preferably 30nm or more, from the viewpoint of crystal grain size. From the viewpoint of transparency, the thickness of the conductive film 3 is preferably 400nm or less, more preferably 300nm or less, and still more preferably 200nm or less.

As described in (4) above, the in-plane crystal grain size of the conductive film 3 is 200nm or more. In the present embodiment, the upper limit value of the crystal grain size of the conductive film 3 is not limited. However, the upper limit of the crystal grain size is preferably about 1000nm or less. The crystal grain size can be measured using an SEM image of the film surface or the cross section (a plane perpendicular to the film thickness direction). That is, the crystal grain size of the conductive film 3 is defined as the crystal grain size in the in-plane direction (the plane orthogonal to the film thickness direction). In the present embodiment, the crystal grain size of the conductive film 3 is controlled within the above range, and even when measurement errors or variations occur due to measurement conditions or the like, for example, by satisfying desired conductivity (surface resistance) while maintaining transparency, it is possible to estimate a configuration including the configuration of the present embodiment.

From the viewpoint of conductivity (surface resistance), the crystal grain size of the conductive film 3 is preferably 300nm or more, and more preferably 400nm or more. From the viewpoint of surface flatness and mechanical strength of the conductive film 3, the crystal grain size of the conductive film 3 is preferably 900nm or less, more preferably 800nm or less, still more preferably 700nm or less, and most preferably 600nm or less.

The surface resistance of the conductive film 3 is preferably 10¹³(omega/port) or less. The surface resistance is more preferably 5X 10¹²(omega/os) or less, and more preferably 5X 10¹¹(omega/os) or less, most preferably 10¹¹(omega/port) or less.

< second embodiment >

In the second embodiment shown in fig. 3, an antireflection film 4 including a conductive film 3 is formed on the surface of a glass lens 2. Each film constituting the antireflection film 4 is a material having excellent transparency.

The antireflection film 4 may be formed, for example, by alternately laminating a low refractive index film and a high refractive index film (having a higher refractive index than the low refractive index film). At this time, as shown in fig. 3, the outermost layer of the antireflection film 4 is formed of a low refractive index film 5 having a lower refractive index than the glass lens 2. Since the conductive film 3 generally has a higher refractive index than the glass lens 2, the conductive film 3 is preferably a high refractive index film located outside the outermost layer of the antireflection film 4.

In the second embodiment shown in fig. 3, the antireflection film 4 is laminated in the order of the low refractive index film 5, the conductive film 3 as a high refractive index film, and the low refractive index film 5 as an outermost layer from the glass lens 2 side. In fig. 3, the antireflection film 4 has a three-layer structure, but the number of layers is merely an example. Thus, the antireflection film 4 may have a two-layer structure of the conductive film 3 and the low refractive index film 5, or may be composed of four or more layers. In this case, the conductive film 3 of the present embodiment may be used for at least one layer of the high refractive index films, but it is preferable that all the high refractive index films are the conductive film 3 of the present embodiment. That is, for example, the antireflection film 4 is formed of a laminated structure of low refractive index film 5/conductive film 3/… … low refractive index film 5.

The upper limit of the number of layers of the antireflection film 4 is not limited, but is, for example, about fifteen layers or less, and preferably about ten layers or less. The number of layers and material of the antireflection film 4 can be variously selected based on the wavelength region in which the reflectance is suppressed.

In the present embodiment, although the material of the low refractive index film 5 constituting the antireflection film 4 is not limited, for example, the low refractive index film 5 is made of a material selected from SiO₂、Al₂O₃And MgF₂Or a mixed film containing two or more kinds of the films.

Although the thickness of the antireflection film 4 is not limited, the thickness (total thickness) of the antireflection film 4 is about 50nm to 500 nm.

The conductive film 3 of the second embodiment has all of the features (2) to (4) mentioned above. As described above, the thickness of the antireflection film 4 in the second embodiment is preferably about 50nm to 500nm, and therefore the thickness of each conductive film 3 is adjusted so as to fall within this range. The upper limit value of each film thickness of the conductive film 3 is adjusted to be lower as the number of stacked conductive films 3 increases. For example, in the second embodiment, when the number of conductive films 3 is about four or less, the film thickness of each conductive film 3 is preferably about 10nm to 100 nm.

The surface resistance of the antireflection film 4 in the second embodiment is preferably 10¹³(omega/port) or less. The surface resistance is more preferably 5X 10¹²(omega/os) or less, and more preferably 5X 10¹¹(omega/os) or less, most preferably 10¹¹(omega/port) or less.

As described above, in the first and second embodiments, the material, film thickness, and crystal grain size of the conductive film 3 are defined.

The relationship between the crystal grain size and the resistivity was examined. When the crystal grain size becomes large, the number of grain boundaries occupied per unit volume becomes small. Since the grain boundary becomes a factor that inhibits the movement of electrons, the grain boundary becomes small and the movement of electrons easily proceeds. In addition, electrons flow along the grain boundaries. When the crystal grain size is increased, the number of grain boundaries per unit volume is decreased, and as a result, the total length of grain boundaries per unit volume becomes shorter. Therefore, the larger the crystal particle size is, the shorter the distance over which electrons flow. Based on the above, it is considered that if the crystal grain size is increased, the resistivity is lowered. This can increase the crystal grain size, thereby improving the conductivity.

In the present embodiment, the titanium oxide used in the conductive film 3 is TiO₂And Ti₃O₅And oxygen deficiency did not occur. Therefore, the transparency of the film is not impaired. The conductive film 3 is formed to have a suitably small film thickness, and can promote the growth of crystal grain size and suitably maintain transparency.

As described above, the dust-proof lens 1 according to the first and second embodiments can obtain excellent conductivity without impairing its transparency, and can effectively improve its dust-proof performance. In addition, in the second embodiment, excellent antireflection effect can be obtained together with dust-proof performance.

< method for producing dustproof lens >

A description is given of a method of manufacturing the dust-proof lens of the first embodiment shown in fig. 2. In the dust-proof lens 1 shown in fig. 2, a conductive film 3 is formed on the surface of a glass lens 2. At this time, by using TiO₂And Ti₃O₅A single layer of titanium oxide or a mixed layer containing 50% or more of the titanium oxide, and the conductive film 3 is formed to have a film thickness of 1nm or more. In this case, the conductive film 3 is formed so that the crystal grain size in the in-plane direction is 200nm or more.

The film formation method is not limited, and the conductive film 3 may be formed by, for example, Ion-Beam assisted vapor deposition (IAD) or Electron Beam (Electron Beam: EB) method. In the ion beam assisted vapor deposition method, during vacuum vapor deposition, gas ions are irradiated to the surface of a glass lens as a substrate with an ion gun. In addition, in the electron beam method, an evaporation material is put into a crucible under a high vacuum environment, and an electron beam is irradiated to the crucible, thereby heating and evaporating the evaporation material in the crucible.

For example, in the present embodiment, Ti is used₃O₅As a vapor deposition material, Ti was evaporated by heating under reduced pressure in a film forming chamber₃O₅. Evaporated Ti₃O₅Facing the surface of the glass lens 2 as a substrate. At this time, with O₂Is bonded to Ti₃O₅To TiO₂And is deposited on the surface of the glass lens 2. Therefore, when the conductive film 3 is formed by the vapor deposition method, the conductive film 3 is easily formed with TiO₂Single phase or TiO₂And Ti₃O₅Mixed phases of (1).

In addition, in the present embodiment, when the conductive film 3 is formed by the vapor deposition method, the substrate heating temperature in the film forming chamber is preferably 250 ℃. The upper limit of the substrate heating temperature is not limited, and may be adjusted to 400 ℃ or lower, for example.

Further, it is preferably 5.0X 10^-3Oxygen gas is introduced into the conductive film under a pressure of Pa or more. Further, it is more preferable to adjust the pressure of oxygen to about 1.0X 10^-2Pa～3.0×10^-2Pa.

By adjusting the substrate heating temperature and the oxygen gas pressure in this manner, the crystal grain size of the conductive film 3 in the in-plane direction can be appropriately controlled to 200nm or more.

In the method for manufacturing a dustproof lens according to the second embodiment shown in fig. 3, an antireflection film 4 is formed on the surface of a glass lens 2. At this time, the low refractive index film 5 and the conductive film 3 are sequentially formed by the vapor deposition method in this state while maintaining the substrate heating temperature in the film formation chamber under a reduced pressure of 250 ℃. At this time, the lamination order or the number of laminations is adjusted so that the outermost layer of the antireflection film 4 is the low refractive index film 5.

In the case of forming the low refractive index film 5 and the conductive film 3 by vapor deposition, ion beam assisted vapor deposition is used, but it is preferable to use MgF for improving adhesion between the films₂In the case of the low refractive index film 5, the ion beam assisted vapor deposition method cannot be used. Thus, for example, MgF is used as the outermost layer₂And the other low refractive index film 5 is made of SiO₂In the case of the iso-oxide film, the low refractive index film 5 and the conductive film 3 are formed by ion beam assisted vapor deposition, except for the outermost layer. And, MgF is formed as an outermost layer by an electron beam method₂. In this way, the antireflection film 4 can be formed by two or more film formation methods depending on the material of the film formation.

In the method for manufacturing the dust-proof lens 1 according to the present embodiment, the conductive film 3 can be formed simply and appropriately, and the conductive film 3 is made of TiO₂And Ti₃O₅A single layer of titanium oxide or a mixed layer containing 50% or more of titanium oxide, having a film thickness of 1nm or more and having a crystal grain diameter in an in-plane direction of 200nm or more. Thus, unlike the conventional art, since titanium oxide is not formed in a film lacking oxygen, the transparency of the conductive film 3 can be maintained. In addition, when the conductive film 3 is formed, the crystal grain size of titanium oxide can be increased to 200nm or more, and thus the resistivity can be reduced. As a result, the conductivity of the conductive film 3 can be improved, and a film that is less likely to be charged can be formed. Therefore, by providing the conductive film 3 of the present embodiment on the surface of the glass lens 2, dustproof glass to which dust is less likely to adhere can be manufactured.

In the second embodiment, an antireflection film using a conductive film can be formed. That is, a dust-proof lens having an antireflection function can be manufactured.

In the above-described method for manufacturing a dustproof lens, the conductive film 3 is formed by a vapor deposition method, but the conductive film 3 may be formed by a sputtering method.