JPH09230493A - Camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent dew condensations to be generated on the surface of a lens and on the inside surface of a front glass by forming the surface layer singly constituted by optical catalystic grains or the surface layer including the optical catalystic grains on the outside surface of a cover case or the inside surface of it and or the surface of the lens. SOLUTION: A surface layer 4 exhibiting hydrophilic nature by being irradiated with UV is formed on the outside surface of a glass plate 3. The surface layer 4 may be singly made of optical catalystic grains, but may be made together with silica and silicone resin or oxide supertough acid. The surface layer 4 may be formed not only on the outside surface of the glass plate 3 but also on the inside surface of the glass plate 3 and on the surface of the lens of a camera body 2 or on all areas ranging over the outer surface and the inner surface of the cover case 1. Moreover, a light source 6 is arranged on the tip of an arm 5 so as to perform an irradiation from the light source 6 to the surface layers 4. Thus, even though humudity in the cover case 1 becomes high, thin water screens are formed on the inside surface of the case 1 and the surface of the lens and the cloudings and dew condensations become to be hardly produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera having a camera body housed in a cover case of a surveillance camera or the like.

[0002]

2. Description of the Related Art Cameras used for in-store monitoring, building intruder monitoring, road congestion and vehicle speed monitoring, and tunnel condition monitoring have been installed for a long time without any change. Often used. Therefore, in order to prevent the camera body from being scratched, for example, the camera body is housed in a cover case whose entire surface is tempered glass. Also,
Not only surveillance cameras but also ordinary cameras include those having a protective cover made of tempered glass in front of the lens.

[0003]

Since surveillance cameras are generally installed in high places, narrow places, etc., they are difficult to clean and remain exposed to rainfall. As a result, the outer surface of the front glass becomes dirty and hard to see, and in the humid season, vapor is accumulated inside, and dew condensation occurs on the lens surface and the inner surface of the front glass. Further, even in a camera provided with a protective cover in front of the lens, when used in a humid place, dew condensation may occur on the surface of the protective cover.

[0004]

The present inventors have made the present invention based on the finding that photocatalyst particles such as titanium oxide have a function of hydrophilizing (superhydrophilizing) the surface of an article. .

The hydrophilizing action of the photocatalyst particles has not been known until now, but it has recently been newly discovered by the experiments of the present inventors. The rationale for this is not completely understood, but when light is applied to the photocatalyst particles, the electrons in the valence band of the photocatalyst particles are excited to generate conduction electrons and holes, and either or Both actions probably polarize the surface and collect polar components such as water and hydroxyl groups. Then, by the cooperative action of either or both of conduction electrons and holes and the polar component, the chemical bond between the adsorbed surface and the pollutant chemically adsorbed on the surface is cut, and chemisorbed water is formed on the surface. It is considered that the water is adsorbed and a physically adsorbed water layer is further formed thereon.

As a specific example, a case where the surface layer is made of a silicone resin having a Si--O bond will be described. Before the photocatalyst particles are irradiated with light, as shown in FIG.
Since the alkyl group (R) is bonded to the atom, the surface layer shows hydrophobicity. However, when light having an energy higher than the band gap energy of the photocatalyst particles is irradiated, first, as shown in FIG. alkyl group (R) by the photocatalytic effects hydroxyl - is substituted (chemisorption), further the hydroxyl ^(OH) - exhibit hydrophilic water molecules in the air are physically adsorbed ^(OH).

In addition, titanium oxide (Ti
O ₂ ) will be described. The state shown in FIG. 2A before the light irradiation is changed to the state shown in FIG. 2A when the light is irradiated, as shown in FIG. 2B. hydroxyl group constituting the (OH ^-) is a Ti atom, a hydrogen atom (H ⁺⁾ is chemically adsorbed to the oxygen atom (O), further the hydroxyl - water molecules and in the air a hydrogen atom (H ^{+) (OH)} Exerts hydrophilicity by physical adsorption.

[0008] In the above description, it is apparent that the decomposition and hydrophilization effect of a substance is completely different, if Shimese concrete examples, TiO ₂ anatase even TiO ₂ oxidation-reduction reaction However, rutile-type TiO ₂ shows almost no decomposition action of the substance based on the redox reaction. Also, among the photocatalysts, tin oxide does not show a decomposition effect of a substance based on a redox reaction. In these photocatalyst particles, the energy level of the conduction band is not sufficiently high, so that the reduction reaction does not proceed. As a result, the electrons excited by the photoexcitation in the conduction band become excessive, and the electron-hole pairs generated by the photoexcitation are oxidized and reduced. It is believed that they recombine without participating in the reaction. However, both rutile TiO ₂ and tin oxide exhibit a hydrophilizing action.

Further, the thickness of the photocatalyst layer needs to be at least 100 nm or more in order to exert the decomposing action of the substance, but it may be several nm or more in order to exert the hydrophilizing action. From these facts, it can be said that the decomposition action of the substance by the photocatalyst and the hydrophilization action are completely different.

The present invention has been made to solve the conventional problems based on the above knowledge, and a camera according to the first invention of the present application is a camera in which a camera body is housed in a cover case. A surface layer consisting of photocatalyst particles alone or a surface layer containing photocatalyst particles was formed on the outer surface or inner surface of the cover case or the surface of the lens.

In the camera according to the second aspect of the present invention, a surface layer made of only photocatalyst particles or a surface layer containing photocatalyst particles is provided on the outer or inner surface of the protective cover provided in front of the lens or the surface of the lens. Formed.

The surface layer consisting of the photocatalyst particles alone or the surface layer containing the photocatalyst particles exhibits hydrophilicity by being irradiated with ultraviolet rays and exhibits a self-cleaning effect, an antifogging effect and the like. In order to effectively exhibit these effects, it is preferable that the hydrophilicity of the surface be 10 ° or less in terms of the contact angle with water. When the surface is made hydrophilic so that the contact angle with water is 10 ° or less, the water droplets attached to the surface of the member instantaneously spread over the entire surface.

The photocatalyst particles are anatase type,
Rutile-type crystalline titanium oxide is preferable, but other photocatalyst particles include ZnO, SnO ₂ , SrTiO ₃ , and
Examples thereof include metal oxides such as WO ₃ , Bi ₂ O ₃ and Fe ₂ O ₃ . Further, when the surface layer is not composed of the photocatalyst particles alone, it is preferable to contain silica or silicone in addition to the photocatalyst particles. Silicone exhibits hydrophilicity by substituting at least a part of organic groups bonded to silicon atoms with hydroxyl groups.

Titania (titanium oxide) will be described as an example of a method of forming a hydrophilic surface layer containing photocatalyst particles. The formation of amorphous titania, the application of silica-containing titania, the application of tin oxide-containing titania, the application of titania-containing Application of a silicone paint and the like can be mentioned.

The formation of amorphous titania is a method in which a surface to be coated is first coated with amorphous titania, which is baked to change the phase to crystalline titania, and any of the following methods can be employed. . (1) Hydrolysis and dehydration condensation polymerization of an organic titanium compound An alkoxide of titanium, for example, tetraethoxytitanium, tetraisopropoxytitanium, tetra-n-propoxytitanium, tetrabutoxytitanium, tetramethoxytitanium, or a hydrochloride such as hydrochloric acid or ethylamine After adding a decomposition inhibitor and diluting with an alcohol such as ethanol or propanol, the mixture is applied after partially or completely promoting the hydrolysis, and then the mixture is applied, and the temperature is from room temperature to 200 ° C. And dry. By drying, the hydrolysis of the alkoxide of titanium is completed to form titanium hydroxide, and a layer of amorphous titania is formed by dehydration-condensation polymerization of titanium hydroxide. Instead of titanium alkoxide,
Other organic titanium compounds such as titanium chelates or titanium acetate may be used. (2) Formation of amorphous titania by inorganic titanium compound Inorganic titanium compound such as TiCl ₄ or Ti (S
Hydrolysis and dehydration polycondensation are performed by applying an acidic aqueous solution of O ₄ ) ₂ and drying at a temperature of 100 to 200 ° C.
Form a layer of amorphous titania. Or it may form a layer of amorphous titania on the surface to be coated by chemical vapor deposition of TiCl _4. (3) Formation of amorphous titania by sputtering A target of metal titanium is irradiated with an electron beam in an oxidizing atmosphere to form a layer of amorphous titania on the surface to be coated.

The application of the silica-containing titania is to form a layer made of a mixture of titania and silica on the surface to be coated. The ratio of silica to the total of titania and silica is 5 to 90 mol%, preferably 10 to 70 mol%, more preferably 10 to 50 mol%. The following method can be employed for forming the surface layer made of silica-containing titania. (1) A suspension containing particles of anatase type or rutile type titania and particles of silica is applied to a surface to be coated, and fired at a temperature equal to or lower than the softening point of the substrate (object to be coated). (2) Based on a mixture of a precursor of amorphous silica (for example, tetraalkoxysilane such as tetraethoxytitanium, tetraisopropoxytitanium, tetran-propoxytitanium, tetrabutoxytitanium, tetramethoxytitanium, etc.) and crystalline titania sol After applying to the surface of the material and hydrolyzing it as necessary to form silanol, heating at a temperature of about 100 ° C. or more and subjecting the silanol to dehydration polycondensation, the titania is bound with amorphous silica. Obtained surface layer (photocatalytic coating). In particular, if the dehydration condensation polymerization of silanol is performed at a temperature of about 200 ° C. or higher, the degree of polymerization of silanol can be increased, and the alkali resistance performance of the photocatalytic coating can be improved. (3) Dispersing silica particles in a solution of amorphous titania precursor (organic titanium compound such as alkoxide, chelate or acetate of titanium, or inorganic titanium compound such as TiCl ₄ or Ti (SO ₄ ) ₂ ) Is applied to the surface of the base material, and the titanium compound is cooled to room temperature for 20 minutes.
By subjecting it to hydrolysis and dehydration polycondensation at a temperature of 0 ° C.,
A thin film of amorphous titania in which silica particles are dispersed is formed. Next, the amorphous titania is changed into crystalline titania by heating to a temperature higher than the crystallization temperature of titania and lower than the softening point of the substrate. (4) Amorphous titania precursor (organic titanium compound such as alkoxide, chelate or acetate of titanium, or inorganic titanium compound such as TiCl ₄ or Ti (SO ₄ ) ₂ ) in a solution of amorphous titania precursor (For example, tetraalkoxysilanes such as tetraethoxytitanium, tetraisopropoxytitanium, tetran-propoxytitanium, tetrabutoxytitanium, tetramethoxytitanium, etc., silanols which are hydrolysates thereof, or polysiloxanes having an average molecular weight of 3000 or less) And apply to the surface of the substrate. Next, these precursors are subjected to hydrolysis and dehydration condensation polymerization to form a thin film composed of a mixture of amorphous titania and amorphous silica. Next, the amorphous titania is changed into crystalline titania by heating to a temperature higher than the crystallization temperature of titania and lower than the softening point of the substrate.

The application of the tin oxide-containing titania is to form a layer made of a mixture of titania and tin oxide on the surface to be coated. The ratio of tin oxide to the total of titania and tin oxide is 1 to 95 mol%, preferably 1 to 50 mol%. The following method can be adopted as a method for forming a surface layer made of titania mixed with tin oxide. (1) A suspension containing particles of anatase type or rutile type titania and particles of tin oxide is applied to a surface to be coated, and fired at a temperature equal to or lower than the softening point of the substrate (object to be coated). (2) Dispersion of tin oxide particles in a solution of a precursor of amorphous titania (organic titanium compound such as titanium alkoxide, chelate or acetate, or inorganic titanium compound such as TiCl ₄ or Ti (SO ₄ ) ₂ ) The resulting suspension is applied to the surface of the substrate, and the titanium compound is heated to room temperature for 20 minutes.
By subjecting it to hydrolysis and dehydration polycondensation at a temperature of 0 ° C.,
A thin film of amorphous titania in which tin oxide particles are dispersed is formed. Next, the amorphous titania is changed into crystalline titania by heating to a temperature higher than the crystallization temperature of titania and lower than the softening point of the substrate.

The application of the titania-containing silicone paint uses a paint in which titania (photocatalyst particles) is dispersed in a film-forming element made of uncured or partially cured silicone (organopolysiloxane) or a silicone precursor. . Specifically, after the above coating material is applied to the surface of the base material, and after the film-forming element is cured, when the photocatalyst is photoexcited, the organic group bonded to the silicon atom of the silicone molecule is replaced with a hydroxyl group by the action of the photocatalyst. Then, the contact angle of the surface with water becomes close to 0 °, and the surface becomes hydrophilic (super-hydrophilic). This method can cure the film forming element at a relatively low temperature, and can be applied as many times as necessary,
In addition, there is an advantage that it can be easily made hydrophilic even by sunlight. The following resins can be used as the resin. Methyltrichlorosilane, methyltribromosilane, methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, methyltri-t-butoxysilane, ethyltrichlorosilane, ethyltribromosilane, ethyltrimethoxysilane, ethyltriethoxysilane, Ethyltriisopropoxysilane, ethyltri-t-butoxysilane, n-propyltrichlorosilane, n-propyltribromosilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltriisopropoxysilane, n-
Propyltri-t-butoxysilane, n-hexyltrichlorosilane, n-hexyltribromosilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-hexyltriisopropoxysilane, n-hexyltrit-butoxysilane, n-decyltrichlorosilane, n-decyltribromosilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, n-
Decyltriisopropoxysilane, n-decyltri-t-
Butoxysilane, n-octadecyltrichlorosilane,
n-octadecyltribromosilane, n-octadecyltrimethoxysilane, n-octadecyltriethoxysilane, n-octadecyltriisopropoxysilane, n
-Octadecyltri-t-butoxysilane, phenyltrichlorosilane, phenyltribromosilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriisopropoxysilane, phenyltri-t-butoxysilane, tetrachlorosilane, tetrabromosilane, tetramethoxy Silane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, dimethoxydiethoxysilane, dimethyldichlorosilane,
Dimethyldibromosilane, dimethyldimethoxysilane,
Dimethyldiethoxysilane, diphenyldichlorosilane, diphenyldibromosilane, diphenyldimethoxysilane, diphenyldiethoxysilane, phenylmethyldichlorosilane, phenylmethyldibromosilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, triethoxyhydrosilane , Tribromohydrosilane, trimethoxyhydrosilane, isopropoxyhydrosilane, tri-t-butoxyhydrosilane, vinyltrichlorosilane, vinyltribromosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltrit-butoxysilane, Trifluoropropyltrichlorosilane, trifluoropropyltribromosilane, trifluoropropyltrimethoxysilane , Trifluoropropyltriethoxysilane, trifluoropropyltriisopropoxysilane, trifluoropropyltri-t-butoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycid Xypropyltrimethoxysilane, γ
-Glycidoxypropyltriethoxysilane, γ-glycidoxypropyltriisopropoxysilane, γ-glycidoxypropyltri-t-butoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldi Ethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriisopropoxysilane, γ-
Methacryloxypropyltri-t-butoxysilane, γ
-Aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltriisopropoxysilane, γ-aminopropyltrit-butoxysilane , Γ-
Mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropyltriisopropoxysilane, γ-mercaptopropyltrit-
Butoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, and their partial hydrolysates or mixtures thereof can be used. .

In order to ensure good hardness and smoothness of the silicone resin film, it is preferable to contain 10 mol% or more of the three-dimensionally crosslinked siloxane. In order to provide sufficient flexibility of the resin film while securing good hardness and smoothness, it is preferable to contain 60 mol% or less of the two-dimensional crosslinked siloxane. In order to increase the rate at which the organic group bonded to the silicon atom of the silicone molecule is replaced with a hydroxyl group by photoexcitation, use is made of a silicone in which the organic group bonded to the silicon atom of the silicone molecule is an n-propyl group or a phenyl group. Is preferred. An organopolysilazane compound having a silazane bond can be used instead of the silicone having a siloxane bond.

The surface layer may contain an oxide superacid. As the oxide superacid, TiO ₂ / W
O ₃ , WO ₃ / ZrO ₂ , WO ₃ / SnO ₂ , Al ₂ O ₃ / SiO ₂
, Etc., and when these oxide superacids are contained in the surface layer, the polarity of the surface becomes extremely large regardless of the presence or absence of light, so that water molecules that are polar molecules are selectively selected over hydrophobic molecules. Adsorb to form a physically adsorbed water layer.

When the camera according to the present invention is installed indoors or in a tunnel, it is preferable to provide a light source for irradiating the surface layer with ultraviolet rays.

[0022]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 3 is an overall perspective view of a camera according to the present invention. This camera has a camera body 2 housed in a cover case 1, and a glass plate 3 is attached to the front surface of the cover case 1.

As shown in FIG. 4, the outer surface of the glass plate 3 has a surface layer 4 which exhibits hydrophilicity by being irradiated with ultraviolet rays.
Are formed. The surface layer 4 may be formed of photocatalyst particles alone, or may be formed together with silica, a silicone resin, or an oxide superacid. Then, in forming the surface layer 4 together with the oxide superacid or the like, they may be simply mixed with the photocatalyst particles, but one of them becomes the upper layer,
The other may be the lower layer. Furthermore, the surface layer 4 may be formed not on the outer surface of the glass plate 3 but on the entire inner surface of the glass plate 3, the surface of the lens of the camera body 2, or the outer surface or inner surface of the cover case 1. .

An arm 5 is provided on the cover case 1, and a light source 6 is attached to the tip of the arm 5 so that the surface layer 4 is irradiated with ultraviolet rays from the light source 6. The light source 6 may be arranged inside the cover case 1.

FIG. 5 is a diagram showing a camera according to another embodiment. In this embodiment, a protective cover 8 made of tempered glass is provided in front of the lens 7 of the camera body 2, and the outside of the protective cover 8 is provided. The surface layer 4 is formed on the side surface or the inner surface.

(Experimental Example) Tetraethoxysilane was coated on the above-mentioned front glass plate or the tempered glass used as a protective cover, and hydrolyzed and dehydrated by polycondensation to form a silica layer, and tetraethoxytitanium was further formed thereon. After coating, hydrolysis and dehydration polycondensation were performed to form an amorphous titania layer. Then, the amorphous titania was phase-changed to anatase type titania by firing at 500 ° C. After this,
A sample was obtained by using a BLB lamp and irradiating with ultraviolet rays at an intensity of 0.5 mW / cm ² for 1 hour.

The obtained sample and a normal tempered glass having no titania layer formed were examined for contact angle with water, antifogging property and antifouling property. Regarding the contact angle with water, the sample of the present invention is 0 °, whereas the ordinary tempered glass is 40 °.
Met. The anti-fog property was examined by blowing.
As a result, no haze was generated on the surface of the sample of the present invention,
Normal tempered glass became cloudy. For antifouling property,
The sample of the present invention and ordinary tempered glass were tilted at 45 °, and a suspension containing hydrophilic carbon black and hydrophobic carbon black at 1.05 g / l was poured into the sample, dried, and washed with water. After repeating the drying cycle 25 times, the change in color difference ΔE ^* before and after the test was measured with a color difference meter (manufactured by Tokyo Denshoku) (JIS H0201).
did. As a result, the sample of the present invention showed a good change in ΔE ^* of <1 and good antifouling property, whereas the ordinary tempered glass had a change of ΔE ^* of> 4.

[0028]

As described above, according to the present invention, a surface layer composed of photocatalyst particles such as titanium oxide alone is formed on the inner surface of a cover case of a surveillance camera or the surface of a lens housed in the cover case. Alternatively, since the surface layer containing the photocatalyst particles is formed, a thin water film is formed on the inner surface of the cover case and the surface of the lens even if the humidity in the cover case is high, so that fogging and dew condensation hardly occur.

Further, according to the present invention, since the surface layer composed of the photocatalyst particles alone or the surface layer containing the photocatalyst particles is formed on the outer surface of the cover case of the surveillance camera or the like, the cover case is self-cleaning during rain. Since the adhered dirt can be removed, it can be used without maintenance for a long time. Furthermore, even a camera installed in a place where there is no rainfall, such as in a tunnel, can be easily washed by watering it with a hose. If a light source that irradiates ultraviolet rays is provided in the cover case or the like, the self-cleaning effect of steam can be exhibited even if the light source is installed in a place where sunlight is not irradiated.

Further, silica is added to the surface layer containing photocatalyst particles,
Or, by including silicone in which some of the organic groups to be bonded are substituted with hydroxyl groups, it is possible to maintain hydrophilicity for a relatively long time without irradiating ultraviolet rays, so use it for a certain period even in the dark. be able to.

Further, the surface layer containing the photocatalyst particles contains TiO ₂ /
WO ₃ , WO ₃ / ZrO ₂ , WO ₃ / SnO ₂ , Al ₂ O ₃ / Si
By including an oxide super strong acid such as O ₂ , the polarity of the surface becomes extremely large regardless of the presence or absence of light. Therefore, water molecules, which are polar molecules, are selectively adsorbed over the hydrophobic molecules to physically A hydrophilic water layer is formed, and the hydrophilicity can be maintained for a certain period even in a dark place.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a process of imparting hydrophilicity to the surface of a silicone resin containing photocatalyst particles.

FIG. 2 is a diagram illustrating a process of imparting hydrophilicity to a surface layer made of photocatalytic particles.

FIG. 3 is a perspective view of a camera according to the present invention.

FIG. 4 is a sectional view of a cover case having a surface layer formed thereon.

FIG. 5 is a diagram showing a camera according to another embodiment.

[Explanation of symbols]

1 ... Cover case, 2 ... Camera body, 3 ... Glass plate, 4
... surface layer, 5 ... arm, 6 ... light source.

Claims (8)

[Claims] 1. In a camera having a camera body housed in a cover case, a surface layer comprising photocatalyst particles alone or a surface layer containing photocatalyst particles is formed on an outer surface or an inner surface of the cover case or a surface of a lens. A camera that is characterized by being. 2. A camera having a protective cover in front of a lens, wherein a surface layer comprising photocatalyst particles alone or a surface layer containing photocatalyst particles is formed on an outer surface or an inner surface of the protection cover or a surface of the lens. A camera characterized by being. 3. The camera according to claim 1 or 2, wherein the photocatalytic particles are crystalline titanium oxide. 4. The camera according to claim 1, wherein the surface layer containing the photocatalyst particles contains silica. 5. The camera according to claim 1, wherein the surface layer containing the photocatalyst particles contains a silicone to which an organic group is bonded, and at least a part of the organic group is substituted with a hydroxyl group. A camera characterized by being. 6. The camera according to claim 1, wherein the surface layer containing the photocatalyst particles contains a superoxide oxide. 7. The camera according to claim 1, wherein the camera is a surveillance camera installed in a building, a vehicle, a road or a tunnel. 8. The camera according to claim 1, further comprising a light source for irradiating the surface layer made of the photocatalyst particles alone or the surface layer containing the photocatalyst particles with ultraviolet rays.