JP2005053468A - Glare preventive mirror for automobile using photochromic compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photochromic mirror structured so that a glass subjected to insulation coating is coated with a photochromic polymeride matrix to a specified thickness, capable of adjusting the transmittance or reflectance. <P>SOLUTION: The mirror consists in a multi-layer structure formed so that zirconium oxide (ZrO<SB>2</SB>) and silica (SiO<SB>2</SB>) are repetitively evaporated alternately on the glass having a high ultraviolet transmittance, and its oversurface is coated with a high-polymer substance containing the photochromic organic compound. A cold cathode-ray tube type fluorescent lamp is installed on the rear of the mirror in order to activate the photochromic coating layer, and the reflectance of the photochromic mirror can be changed by irradiating the photo-discoloring substance coating surface uniformly. When the intensity of the light applied externally is sensed by a photo-sensor and signal is given, a voltage control circuit acknowledges the signal, and the ultraviolet ray emission amount is adjusted by supplying the required voltage thereto to the lamp, and it is possible to change the reflectance of the mirror. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an anti-glare mirror for automobiles that can protect a driver from visual interference caused by strong light of a car or sunlight.

  Conventionally, various methods and apparatuses for giving light discoloration to a vehicle rearview mirror and a side mirror and preventing glare due to reflection of light reaching the mirror from the back are known. A device using a liquid crystal compound is widely known (see Patent Documents 1 to 4, etc.).

  However, such a mirror using a liquid crystal compound is fast and stable, but has a high manufacturing cost and a small number of companies monopolize the technology. Was requested.

  As an alternative method, a method of coating a glass or mirror with a photochromic organic compound has been proposed. The photochromic organic compound is a substance having a characteristic of changing to a specific hue by ultraviolet rays contained in light and returning to the original hue when the light is blocked. A problem of the photochromic device using such a compound is that the photochromic organic compound is not discolored at night without sunlight.

  Recently, in order to solve such problems, compounds and devices that change hue even at night without sunlight have been disclosed (Patent Documents 5 to 8).

  In these patents, an ultraviolet transmissive mirror is proposed that can further activate a photochromic organic compound by coating an insulating thin film on glass. This mirror is formed by repeatedly depositing a material having a high refractive index and a low refractive index in a multilayer structure using an insulating thin film coating that is generally used for optical purposes. The light wavelength band is reflected to prevent glare from visible light.

  Various materials can be used for insulating thin film coating, but the range of UV wavelength range that can be transmitted, the degree of transmittance, and the thickness of the thin film will also vary depending on the type of material used and the process conditions during thin film deposition. Become.

US Pat. No. 6,175,479 US Pat. No. 6,175,441 US Pat. No. 6,193,912 US Pat. No. 6,193,378 US Pat. No. 5,373,392 British Patent Publication No. 2115573 European Patent Publication No. 0568210 JP-A-6-51352

  Important characteristics of anti-glare devices that use photochromic organic compounds include changes in reaction speed, uniformity, and reflectance during discoloration, as well as important matters regarding the life and durability of UV lamps. become.

  Titanium used as a high refractive index layer material in the above-mentioned US Pat. No. 5,373,392 has the advantage of blocking the visible light region with a small number of layers due to the characteristics of the material, but the ultraviolet wavelength region of 365 nm However, there is a disadvantage that the transmittance is relatively low. If the ultraviolet ray transmittance is low, the reaction rate of the photochromic organic compound becomes slow and the color change property of the photochromic material becomes poor, such as a thin hue.

  Further, in the case of the above-mentioned patent using a low-pressure mercury lamp used as an ultraviolet ray supply source, it is in the form of a filament electrode, and there is a problem that the filament is easily short-circuited in an environment where external vibration is severe such as an automobile. Furthermore, if the heat generated by the electrical resistance of the filament is sustained, the high heat interferes with the reaction of the photochromic organic compound, and the original hue remains.

In order to solve such a problem, the present inventor selected zirconium oxide (ZrO ₂ ) and silica (SiO ₂ ) as a conventional problem, and formed a high-UV-transmissive barrier thin film coating on the glass, In addition, these are repeatedly deposited by a unique optical design to induce rapid discoloration of the photochromic coating layer by forming a multilayer structure, which can be completely eliminated by changing the reflectivity and vibration. The present invention has been completed on the basis of the discovery that it can be completely eliminated by applying such a lamp having excellent durability against the external environment.

  Another object of the present invention is to induce uniform photochromicity over the entire area of the coating layer by uniformly dispersing ultraviolet rays emitted from the ultraviolet source in the photochromic coating layer.

  According to the configuration of the insulating thin film coating layer of the present invention, the transmittance in the ultraviolet wavelength band is increased, and the reflectance in the visible light wavelength band is decreased, so that it has an antiglare effect than the conventional technique. In addition, the diffuser plate whose surface has been roughened uniformly irradiates the entire area of the photochromic coating layer with ultraviolet rays, so that the photochromic coating layer can react sensitively and induce rapid and uniform photochromic coating. . In addition, by applying a cold cathode fluorescent lamp, the durability life corresponding to the vibration of the vehicle is extended and the heat generation of the lamp is suppressed to prevent the problem of deterioration of the discoloration reaction of the photochromic coating layer over time. can do. Therefore, the present invention enables anti-glare for a long time even at night.

  The present invention provides an automotive color changing mirror capable of adjusting transmittance or reflectance by coating a glass with a photochromic polymer matrix containing a photochromic organic compound at a certain thickness.

  In the present invention, the reflectance or transmittance of the mirror varies depending on the characteristics of the photochromic organic compound. A photochromic organic compound is a substance having a reversible hue change characteristic, i.e., when exposed to sunlight or ultraviolet rays, the molecular structure is activated to change to a specific hue, and when the light is blocked, It means a substance that returns (returns) to hue. Typical photochromic organic compounds that are generally known include spiropyran materials, spirooxazine materials, viologen materials, diarylethene materials, and the like.

  Generally, a photochromic organic compound such as spiropyran or spirooxazine is in the form of a solid powder. Since these cannot have a photochromic property in a solid state, in many cases, a photochromic organic compound is mixed with a polymer host, and a product is manufactured using this mixture as a coating material. These properties, for example, characteristics such as a color change speed, a color recovery speed, transmittance, reflectance, and durability, are determined by the affinity between the photochromic organic compound and the polymer matrix.

  The following materials are known as polymeric hosts for photochromic organic compounds: cellulose resins such as ethyl cellulose, acrylic resins such as polymethyl methacrylate, silicone resins, epoxy resins, polycarbonates, polystyrene, poly Vinyl alcohol, polyvinyl chloride, polyurethane, and their copolymer polymers.

  FIG. 1 shows the internal structure of a photochromic mirror for automobiles. FIG. 1a shows a state in which the ultraviolet lamp (6) is OFF, and FIG. 1b shows a case in which it is ON.

The schematic configuration of the mirror structure of the present invention is as follows: protective glass (1), UV blocking coating layer (2), polymer coating layer (3) containing a photochromic organic compound, insulating thin film coated mirror (4) ), A diffusion plate (5), an ultraviolet lamp (6), and an aluminum reflector (7), and a plastic housing (10) surrounds the outside for supporting such an internal structure.
The housing (10) is preferably made of a plastic material suitable for an automobile, and a rectangular product is generally used in many cases, but is not limited thereto.

  From FIG. 1a, it is apparent that almost all of the visible light flowing from the outside is reflected by the insulating thin film coating mirror (4). At this time, it goes without saying that the ultraviolet lamp (6) is in an OFF state, and the ultraviolet light contained in the external light is not allowed to flow into the housing (10) by the ultraviolet blocking coating layer (2). The discoloration coating layer (3) is not discolored.

  On the other hand, FIG. 1b shows that a considerable amount of visible light from the outside is absorbed by the photochromic coating layer (3) to reduce the amount of reflection, and an ultraviolet lamp (6) is used to discolor the photochromic coating layer (3). ) Indicates light emission.

  The insulating thin film coating mirror (4) is composed of an insulating thin film coating having a multilayer structure in which a material having a high refractive index and a material having a low refractive index are repeatedly deposited by a specific optical design. The insulating thin film coating reflects the visible light (380 to 700 nm) wavelength band by repeatedly depositing a low refractive index layer and a high refractive index layer, so that the ultraviolet lamp (6) installed therein cannot be seen from the outside. The ultraviolet wavelength band (340 to 380 nm) is an effective method for transmitting.

  For insulating thin film coating, oxides of various materials including titanium oxide are used as the material forming the high refractive index layer, and many high refractive index oxides including silica provide low refractive index. Used as a substance. At this time, the range of the ultraviolet wavelength band that can be transmitted, the degree of transmittance, and the thickness of the thin film also vary depending on the material to be taken and the optical design suitable for the material.

  For example, in US Pat. No. 5,373,392, titanium used as a high refractive index layer material has the advantage of blocking the visible light region with a small number of layers due to the characteristics of the material. There is a disadvantage that the transmittance in the wavelength region is relatively low. If the ultraviolet light transmittance is low, the color change characteristics of the photochromic material also become low, so that the reaction speed at the time of color change is slow and the hue becomes thin.

  On the other hand, in the present invention, the insulating thin film coating layer is formed so as to increase the transmittance in a desired wavelength band by the optical design of adopting zirconium oxide as the high refractive index layer material. As a result, it was possible to maintain the transmission efficiency of 90% or more in the ultraviolet wavelength band of 365 nm as shown in FIG.

  FIG. 3 shows a reflection spectrum of a multiple insulating thin film coating structure in which zirconium oxide is selected as the high refractive index layer, silica is selected as the low refractive index layer, and these are repeatedly deposited. Here, the high refractive index layer and the low refractive index layer were measured in a state where 35 layers were repeatedly deposited. The number of such repetitive layers is not particularly limited, but about 25 to 40 layers are desirable in order to efficiently achieve the object of the present invention, and the coating method is vapor deposition using an ion beam, sputtering, etc. The usual method can be used.

  By the way, the polymer coating layer (3) in which the photochromic organic compound is blended is formed on the insulating thin film coating mirror (4), and a transparent high polymer containing an ultraviolet absorber is added to the outside of the photochromic coating layer (3). An ultraviolet blocking coating layer (2) made of molecules is installed. As a result, it was possible to completely block leakage of ultraviolet rays transmitted without being partially absorbed by the photochromic coating layer (3), and to prevent contamination and damage of the photochromic coating layer.

  As the ultraviolet lamp (6) for activating the photochromic substance, a cold cathode fluorescent lamp (CCFL for ultraviolet rays) is used, and is arranged behind the insulating thin film coating mirror (4). In the case of the low-pressure mercury lamp used in the conventional patent, the electrode is a filament type, and there is a problem that the filament breaks due to external vibration or the like, or the discoloration reaction of the photochromic coating layer is prevented by heat generation due to electric resistance.

  That is, in the case of a low-pressure mercury lamp, if the duration of light emission of the lamp is increased, the temperature inside the housing increases due to the temperature rise due to the electrical resistance of the filament, and the discoloration reaction of the photochromic polymer coating layer is disturbed. Therefore, there arises a problem that the discoloration becomes light or returns.

  However, since the ultraviolet lamp (6) of the present invention uses a cold cathode fluorescent lamp, the photochromic coating layer is maintained in a discolored state as it is even after a long light emission duration. Become. Therefore, in the present invention, when the lamp having a diameter of 2 mm is applied, the lamp can be miniaturized and the housing can be designed to be thin, as well as improving the lamp life and the color change duration. As a result of measuring the reflection of visible light through experiments, the results shown in Table 1 below were obtained.

  That is, the conventional low-pressure mercury lamp and the cold cathode fluorescent lamp of the present invention (diameter 2 mm) were installed in the same housing. In the housing where the low-pressure mercury lamp is mounted, a photochromic coating layer mainly composed of titanium oxide is formed on the high refractive index layer, and in the housing where the cold cathode fluorescent lamp is mounted, the high refractive index After forming a photochromic coating layer containing zirconium oxide as a main material, a power source was applied to each ultraviolet light source, and the reflectance of visible light was measured at intervals of 20 minutes.

  From the results of Table 1 above, it can be seen that when a low-pressure mercury lamp is used, the discoloration of the photochromic coating layer becomes thinner with the passage of time, and the reflectance of visible light also increases with the passage of time. However, when a cold cathode fluorescent lamp is used, it is clear that the visible light absorption rate is excellent even after 3 hours.

  However, since the diameter and the number of installed ultraviolet lamps (6) according to the present invention vary depending on conditions such as the area of the photochromic coating layer (3) to be discolored and the improvement in the uniformity of discoloration, the above-mentioned standard of the experimental values It is not limited to.

  By the way, as another method for making the discoloration action of the photochromic coating layer (3) uniform, a reflector (7) with aluminum deposited on the rear surface of the lamp can be installed. Between the ultraviolet lamp (6) and the insulating thin film coating mirror (4), a diffusing plate (5) that illuminates the surface and scatters and transmits light is arranged to diffuse the ultraviolet rays emitted from the lamp (6). The plate (5) can be uniformly diffused and dispersed to uniformly irradiate the entire area of the photochromic coating layer (3).

  The aluminum reflector (7) is a product coated with aluminum by a physical vapor deposition method, and has a reflectance of 96% or more and a diffuse reflectance of 50% or more.

  A voltage control circuit (8) for turning on / off the ultraviolet lamp (6) is installed behind the aluminum reflector (7), and this voltage control circuit (8) is installed in a predetermined part of the housing (10). By detecting and operating the signal of the optical sensor (9) that senses the amount of external light, it acts to supply or block an appropriate voltage to the ultraviolet lamp (6).

  Hereinafter, the present invention will be described in detail with reference to examples. However, these examples are illustrative of the invention and are not intended to limit the scope of the invention.

Example 1
The photochromic organic compound coating solution was prepared by dissolving 1 g of 1,3,3-trimethylindolinonaphthospirooxazine in 50 g of tetrahydrofuran, 10 g of polymethyl methacrylate and 0.1 g of UV-5411 (manufactured by Cyasorb) Was prepared.

  The prepared coating solution was coated on an insulating thin film coated mirror having a size of 5 cm × 25 cm to a thickness of 15 μm using a spin coater, and then dried in an oven at 60 ° C. for 1 hour to form a photochromic mirror. Manufactured.

  The reflectivity of the photochromic mirror was measured using a spectrophotometer (Minolta CM-3600D). As a result of measuring the change in reflectance at 610 nm, which is the visible light wavelength band before and after the color change, the reflectivity, which was 95% before the color change, decreased to 7% after the color change. Here, the above-mentioned measurement was measured in a discolored state after being exposed to a 365 nm ultraviolet ray cold cathode tube lamp for 1 minute.

Example 2
In order to confirm the discoloration characteristics depending on the type of the high refractive index material layer, a photochromic coating mirror using titanium oxide and zirconium oxide was prepared and compared.

  In the case of titanium, 25 titanium oxide layers and 25 silica layers were formed in order to block visible light. On the other hand, zirconium was able to block visible light by forming 35 layers each of zirconium oxide and silica. As a result of measuring the transmittance at 365 nm in the ultraviolet wavelength band of the deposited insulating thin film coating mirror, 48% of the mirror using titanium as the high refractive index layer material is transmitted, and 90% of the mirror using zirconium is transmitted. (See FIG. 2).

  Further, a photochromic coating layer was formed on each deposited mirror through the same procedure as in Example 1, and the reflectance during the color change was measured using a spectrophotometer. As a result of the measurement, the reflectance at 610 nm which is a visible light wavelength band was 23% reflected in the mirror using titanium, and only 7% was reflected in the mirror using zirconium (see FIG. 3). .

Sectional drawing showing the visible light reflection by the Example of this invention (a state with an ultraviolet lamp OFF). Sectional drawing showing the visible light reflection by the Example of this invention (a state with an ultraviolet lamp ON). The graph showing the transmittance | permeability according to the wavelength band of the insulating thin film coating mirror by the Example of this invention. The graph showing the reflectance according to wavelength band of the insulating thin film coating mirror in which the photochromic substance coating layer by the Example of this invention was formed.

Claims (3)

An ultraviolet blocking layer (2) from the outside, a photochromic coating layer (3) by ultraviolet rays, and an insulating thin film coating mirror (4) on which high refractive index and low refractive index materials are laminated are sequentially laminated inside a housing (10). In the anti-glare mirror structure for a vehicle in which an ultraviolet lamp (6) and a reflector (7) are mounted, and if necessary, a light quantity measurement sensor (7) is further attached to control the light emission of the lamp,
The high refractive index material and the low refractive index material are respectively composed of zirconium oxide (ZrO ₂ ) and silica (SiO ₂ ), and these are repeatedly laminated in a range of 25 to 40 layers, respectively. Used car anti-glare mirror.   The antiglare mirror for automobiles according to claim 1, wherein a photochromic compound is used, wherein a diffusion plate (5) is mounted on the inner surface of the insulating thin film coating mirror (4). The anti-glare mirror for automobiles according to claim 1, wherein the ultraviolet lamp is a cold cathode fluorescent lamp (Cold Cathode Fluorescent Lump).

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