JPH06102541A - Antidazzle mirror for vehicle - Google Patents

Abstract

PURPOSE:To provide the mirror for vehicles with which light reflectivity can be adjusted by impression of a shearing stress thereto by clamping an elastic film contg. light absorptive particulates arranged in the specified direction with substrates between a pair of the substrates. CONSTITUTION:The viscoelastic material 9 contg. the light absorptive particulates or particulate assemblage 10 arranged with the specified direction with the transparent substrate 7 is disposed between the transparent substrate 7 and the counter substrate 5. The viscoelastic material 9 is preferably constituted of an org. or inorg. crosslinked polymer having a shearing modulus G' in a 1X10<2=G'<=1X10<7>dyncm<-2> range at ordinary temp. The particulates to be incorporated therein absorb the greater part of incident light and the rate of decrease in the reflectivity at the time of impressing the shearing stress increases if the light absorbance of the particulates is high. Since the control of the reflectivity of light in a wide range is possible, the particulates having the high light absorbance are preferable. The shape anisotropic particulates of graphite, etc., are more particularly preferable. An electrode 12 for driving a piezoelectric element is used as the device for impressing the shearing stress.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle antiglare mirror using an elastic film containing light-absorbing fine particles or fine particle chains used as a rearview mirror for automobiles and the like.

[0002]

2. Description of the Related Art Conventionally, when driving a car at night,
There was a safety problem that the light rays from the headlamps of the following vehicles were reflected by the rearview mirror and dazzled the driving vehicle.

Therefore, in order to solve such a problem, a light transmittance control element such as a liquid crystal element, a photochromic element, an electrochromic element or the like is applied to a rearview mirror so that a light beam from a headlamp of a following vehicle can be emitted. It has been carried out to control the reflectance to give an antiglare effect (see, for example, JP-A-60-104921 and 63-).
289536).

[0004]

However, the liquid crystal element is not only deteriorated by ultraviolet rays, but also has a drawback that the liquid crystal is scattered when it is broken. Further, the photochromic device has a slow response speed and is difficult to be actively controlled. Further, the electrochromic device is usually composed of tungsten oxide and iridium oxide and is very expensive.

The present invention has been made in view of the above problems of the prior art, and sandwiches an elastic film containing light absorbing fine particles or fine particle aggregates arranged in a substantially constant direction with respect to a substrate. An object of the present invention is to provide an antiglare mirror for a vehicle that can adjust the light reflectance by exerting a shear stress between a pair of substrates.

[0006]

That is, according to the present invention, a light-absorbing fine particle is provided between a reflective substrate on the rear surface and a transparent substrate on the front surface, and interposed between the both substrates, and arranged in a substantially constant direction with respect to the transparent substrate. Alternatively, it is an antiglare mirror for a vehicle, which comprises a viscoelastic body containing a fine particle aggregate and a device for exerting a shear stress on the viscoelastic body.

The antiglare mirror of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a diagram showing an example of the antiglare mirror of the present invention in a state where no shear stress is applied (high reflectance state), and FIG. 2 is a state in which a shear stress is applied by applying a voltage. It is a figure which shows an example of the anti-glare mirror of this invention in a (low reflectance state). Hereinafter, the antiglare mirror of the present invention will be described with reference to FIGS. 1 and 2.

In FIGS. 1 and 2, 1 is a fixture for mounting a reflecting mirror, 2 is a link extending from the fixture 1, 3 is a light-reflecting substrate, 4 is a metallic reflection film, and 5 are the above 3 and 4 A reflecting mirror substrate, 6 a reflecting mirror frame, 7 a transparent substrate, 8 a drive power source, 9 a viscoelastic body, 10 fine particles or fine particle aggregates, 11 an intermediate film for alignment, and 12 a piezoelectric element. Driving electrodes, and 13 are driving piezoelectric elements.

As the transparent substrate 7, in addition to a glass substrate such as soda lime glass, a light transmissive member, for example, a polymer such as polycarbonate or polyethylene terephthalate can be applied. Further, the shape, size, etc. of the substrate 6 are appropriately determined according to the design of the mirror.

When the suspension in which the fine particles 10 are dispersed is an electrorheological fluid, the fine particles 10 are electrically polarized when an electric field is applied to the suspension, and a + portion and a − portion are formed to form a dipole. . The particles that have become dipoles move so as to bring the + side and the − side into contact with each other and bond to each other, forming a chain of particles in the electric field direction.

When the suspension is such an electrorheological fluid, it is effective to apply an electric field in order to arrange the fine particles or the fine particle aggregates 10 perpendicularly to the substrate as shown in FIG. . Therefore, it is desirable that the transparent conductive film is provided inside the front transparent substrate 7 and the reflective film 4. As the transparent conductive film, any one can be used as long as it has been conventionally used for a solar cell, a liquid crystal element or the like, and is not particularly limited. Specific examples thereof include SnO ₂ film and ITO film. Further, the film thickness is not particularly limited.

A reflective metal film can be used as the counter electrode. Aluminum, chromium, nickel, stainless steel, silver and the like can be applied as the metal film material.

When the fine particles are a conductor, it is effective to coat the fine particles and / or the transparent electrode with an insulating film.

As the fine particles or the fine particle aggregate 10,
Any material can be applied as long as it is a material that is polarized or magnetized by an electric field and exhibits an electrorheological effect or a magnetic viscous effect in which when dispersed in a liquid, the particles or particle aggregates 10 are arranged in the electric field or magnetic field direction. Although possible, in order to obtain excellent antiglare performance, it is preferable that the absorbance of visible light is as high as possible.

The fine particles having high absorbance in the visible region preferably have an extinction coefficient of 1 × 10 ⁴ cm ^-1 or more. The shape of the fine particles is preferably one having shape anisotropy, and the minor axis thereof is preferably 0.1 μm or less and the aspect ratio is 3 or more.

When the absorbance of the fine particles is high, most of the incident light is absorbed to increase the amount of decrease in reflectance when shear stress is applied. As a result, the reflectance of light can be controlled in a wide range. . Thereby, an excellent antiglare effect is realized. Further, when the fine particles have a shape anisotropy, the attractive force between the fine particles when an external field is applied becomes large, so that chain formation of particles becomes easy. Furthermore, the smaller the minor axis size, the higher the transmittance when no shear stress is applied (high reflectance state). Thus, the shape anisotropy of the fine particles and the miniaturization of the minor axis size also play a major role in improving the reflectance control performance.

Examples of such shape anisotropic fine particles include graphite, TiO _x , TiO _x N _y , titanium oxide coated mica, TiO _x coated mica, TiO _x N _y coated mica, titanium oxide coated glass flake and TiO _x. Coated glass flakes, TiO _x N _y coated glass flakes, γ-iron oxide, metal titanates, iron, cobalt, magnetite, barium ferrite, chromium (IV), various metal-coated mica, various metal-coated glass flakes and the like. To be

These fine particles are not necessarily required to have a shape anisotropy, and if their anisotropy is small, or if their suspension exhibits an electrorheological effect or a magnetic viscous effect, it is used. can do.

The range of x in the TiO _x is 1 ≦
x ≦ 2 is preferable, but it is 1.4 when the absorption coefficient is taken into consideration.
It is more desirable that the range of 0 ≦ x ≦ 1.80.
If expressed in terms of absorption coefficient, it is preferably 5 × 10 ³ cm ⁻¹ , more preferably 1 × 10 ⁴ cm ⁻¹ or more.

The range of x + _y in TiO _x N _y is 1.37 ≦ x + y ≦ 1.95, and the range of y is 0.15.
It is preferable that ≦ y ≦ 0.92 from the viewpoint of extinction coefficient.
In this composition range, the extinction coefficient reaches 5 × 10 ³ cm ⁻¹ or more.

As the viscoelastic body 9, when a shear stress is exerted, a shear deformation of submicron to several tens of microns occurs with a force that does not break the substrate, and when the force is released, fine particles or a fine particle aggregate 10 is released. Any viscoelastic body can be used as long as it can maintain the original arrangement of
For that purpose, the shear modulus (G ′) of the viscoelastic body 9 is 1 × 10 ² ≦ G ′ ≦ 1 × 10 ⁷ dyncm ^{−2 at} room temperature, and further 1 × 10 ³ ≦ G ′ ≦ 1 × 10 ⁵ It is preferably composed of a crosslinked organic and / or inorganic polymer in the range of dyncm ⁻² (measurement frequency = 1 Hz).

The shear modulus is 1 × 10 ² dyncm
When it is smaller than ^-2 , the viscoelastic body 9 is too soft to maintain the arrangement of the fine particles or the fine particle aggregates 10. Further, when it is larger than 1 × 10 ⁷ dyncm ⁻² , it takes a very large force to displace the reflective substrate 5,
It is practically difficult to use.

As the viscoelastic body 9, a thermosetting polymer, a photocurable polymer, an electron beam curable polymer, a radiation curable polymer, a plasma curable polymer or a hydrogen bond, a three-dimensional network by electrostatic bond or coordinate bond. Those having a structure can be applied.

Specifically, various vinyl monomers and divinyl compounds, acrylic acid, methacrylic acid, acrylamide, polymers having a hydroxyl group and aldehydes, N-methylol compounds, dicarboxylic acids, polyvinyl alcohol and 2
-Mixture of oxazolines, polyethylene, α-substituted polymer, polyvinylidene fluoride, polytetrafluoroethylene, nylon, polyvinyl fluoride, polyvinyl alcohol interpolymer complex, polyvinyl alcohol
-Cu ²⁺ , acrylic acid-Fe ³⁺ , acrylic acid-Cu ²⁺ , polymer complex, polyorganosiloxane and the like can be used.

Since the antiglare mirror of the present invention is used in a vehicle, a viscoelastic body having a small temperature dependence of viscoelastic modulus is used from the viewpoint of driving although the required operating temperature range is relatively narrow. Is desirable. From this perspective,
Among the viscoelastic materials, polyorganosiloxane is particularly preferable. Further, polyorganosiloxane is a material excellent in heat resistance and light resistance, and is an optimum material as a viscoelastic body for an antiglare mirror.

When such a viscoelastic body is subjected to shear stress as described above, it is deformed according to the stress,
The state of returning to the original state when the stress is removed can be repeated with good reproducibility, and the repeatability of the antiglare mirror is improved.

Various methods are conceivable as a device for exerting a shear stress, and the device is not particularly limited.
A piezoelectric element that converts an electric signal into a mechanical signal can be given.
By using the driving piezoelectric element 13 as described above, the reflective substrate 5 can be displaced by an arbitrary distance by controlling the voltage. That is, it is possible to obtain an arbitrary relative displacement amount between the substrates. As the material of the driving piezoelectric element 13,
A barium titanate crystal or the like can be applied.

The viscoelastic body 9 is made into a viscoelastic body in a state where an electric field or a magnetic field is applied, and the fine particles or the fine particle aggregates 10 therein are oriented substantially perpendicular to the front transparent substrate 7, The aggregates are formed in the aligned state.

In order to efficiently control the light reflectance when a shear stress is exerted, the content of fine particles is 0.07 to 7.0.
The volume of the viscoelastic body 9 is preferably 5 to 100 μm, more preferably 30 to 70 μm, and further preferably 0.7 to 2.3% by volume.

The size of one fine particle or fine particle aggregate 10 is preferably 10 μm or less, and more preferably 4 μm or less. Further, the number density in the plane of the fine particles or the fine particle aggregate 10 is 2.0 × 10 ⁵ particles / cm ² , and further 7.0 × 10.
^It is preferably ⁵ pieces / cm ² .

The antiglare mirror of the present invention uses a semi-solid dispersion medium that does not scatter upon leakage or damage as a fine particle dispersion medium, and reflects in multiple stages by adjusting the shear stress exerted on the dispersion medium. The reflectance can be controlled, and the reflectance control performance is extremely high.

Next, regarding the method of manufacturing the antiglare mirror of the present invention, there are two methods for arranging the particles or the particle aggregates in the direction perpendicular to the substrate: a method of applying a voltage and a method of applying a magnetic field. There is a way.

First, as a method for producing an antiglare mirror by applying a voltage, a suspension containing fine particles polarized by an electric field is sandwiched between a pair of substrates having electrodes formed inside, and then the substrate is prepared. A method may be mentioned in which the suspension is made into a viscoelastic body while applying a voltage in between. Of course, one of these two electrodes is a transparent electrode coated on the transparent substrate 7, and the reflective film 4 coated on the light reflective substrate 3 can be used as the counter electrode. .

In this method, first, one kind or two or more kinds of fine particles are mixed with the raw material liquid of the viscoelastic body, and if necessary, a catalyst or the like is added to form a suspension, and the suspension is placed on a substrate. For example, it is applied by a method such as screen printing or a doctor blade, and is set so as to have a constant space between a pair of substrates. Next, operations such as heating and light irradiation are performed while applying a voltage, and the suspension is made into a viscoelastic body while the fine particles are oriented in an aggregate form. In this case, the thickness of the viscoelastic body is determined by the distance between the set substrates.

As an example of the method of setting the substrates, it is possible to keep the distance between the substrates constant by adding, for example, spherical fine particles having a uniform particle size to the suspension as spacers. In this case, the distance between the substrates is determined by the diameter of the spacer. Further, in the case of the room mirror, since the area thereof is relatively small, it is possible to provide a spacer having a constant thickness around the substrate.

The applied voltage varies depending on the viscosity of the dispersion and the chain forming ability of fine particles, but is usually 10 ⁴ Vcm ^-1.
The above electric field is sufficient.

The viscoelasticity of the suspension is obtained by allowing a suspension containing fine particles sandwiched between a pair of substrates to be left standing while heating while applying voltage with an electrode formed on the surface of the substrates, heating, light irradiation, and electron beam irradiation. Irradiation, radiation irradiation, plasma irradiation, or the like is performed to make the suspension viscoelastic.

In this case, in order to obtain good adhesion between the final viscoelastic body and the substrate, viscoelasticization of the suspension described above
It is desirable to carry out the process while sandwiching between the substrates, and it is particularly preferable to use a thermosetting or photocurable polymer as the dispersion liquid of the fine particles. Further, from the viewpoints of the weather resistance and the temperature dependency of the elastic modulus, the thermosetting polyorganosiloxane or the photocuring polyorganosiloxane is particularly preferable.

In order to further improve productivity,
A viscoelastic body containing fine particle chains is prepared by inserting a reflection substrate coated with a fine particle dispersion liquid dispersed in a viscoelastic body material liquid between external parallel plate electrodes and heating while applying a high electric field. A reflective substrate coated with a film can be obtained.

Further, in order to obtain a sufficient adhesive force between the viscoelastic film and the front transparent substrate, dumilan (Takeda Pharmaceutical Co., Ltd.
An anti-glare mirror can be produced by combining it with a front transparent substrate through an intermediate film (made by, for example). According to this method, the transparent electrode on the front transparent substrate becomes unnecessary,
Cost reduction is possible.

Next, in the method of manufacturing an antiglare mirror by applying a magnetic field, a suspension containing magnetic fine particles is sandwiched between a pair of substrates and then the suspension is applied while applying a magnetic field between the substrates. Is a viscoelastic body, and is exactly the same as the method for producing the antiglare mirror by the method of applying the voltage described above except that a magnetic field is applied to the suspension.

As a method of applying a magnetic field, for example, two solenoids connected in series may be installed in parallel and a parallel magnetic field generated between them may be used.

The strength of the magnetic field varies depending on the type of magnetic particles used, but for example, in the case of γ-iron oxide, a magnetic field of 5 kOe or more is used in order to obtain a good arrangement of fine particles. is necessary.

Further, an antiglare method using the antiglare mirror of the present invention will be described. In the antiglare method, the antiglare mirror having the above-mentioned configuration is used, and shearing stress is exerted on the viscoelastic body by an apparatus for exerting shearing stress.

In the case of FIG. 1, the fine particles are arranged substantially perpendicular to the substrate. In this case, since the light-shielding area of the fine particles is small, most of the incident light from the headlamp of the following vehicle is transmitted and reflected by the metallic reflection film 4. Except for driving in a tunnel, etc., it is mainly used in this state during daytime driving.

On the other hand, the piezoelectric element driving electrode 12,
When a voltage is applied between 12 to control the displacement amount of the driving piezoelectric element 13 and a shear stress is applied to the viscoelastic body 9 containing the fine particles or fine particle aggregates 10, the fine particles or fine particle aggregates 10 are As shown in 2, the long axes are arranged parallel to each other with the major axes inclined in the shear stress direction.

In the anti-glare mirror in this state, since the light-shielding cross-sectional area of the fine particles is increased, most of the incident light from the following vehicle is absorbed, and a good anti-glare action is obtained. By setting the mirror in this state when driving in a tunnel as well as during nighttime driving, it is possible to prevent glare due to the headlights of the following vehicles and improve safety.

The relative displacement amount between the substrates for exerting the shear stress in this case varies depending on the physical properties and thickness of the viscoelastic body, but is 10 when the substrate thickness is about 50 μm.
The transmittance is considerably reduced when the displacement is more than μm. Further, when the extinction coefficient is sufficiently large, the transmittance change width increases almost in proportion to the displacement amount.

When the voltage application between the piezoelectric element driving electrodes 12 and 12 is stopped and the shearing force is released, the fine particles or the fine particle aggregate 10 returns to the initial state as shown in FIG. Further, when the viscoelastic body 9 is not completely returned to the initial state due to the stress relaxation, the actuator can be forcibly returned by using an actuator or the like not shown. This point is important in that the switching performance of this device is not affected by the stress relaxation of the viscoelastic body.

Since such an antiglare method is used, the reflectance can be controlled in multiple stages by changing the displacement amount of the substrate.

[0052]

The antiglare mirror for a vehicle of the present invention has a large antiglare effect and response speed, and is excellent in weather resistance because it is made of an inorganic material. Moreover, since it is an all-solid type, safety at the time of breakage is secured. Further, since the structure is simple, there is an advantage that the cost can be reduced.

[0053]

Example: The extinction coefficient is about 10 ⁵ cm ^-1 , and the major axis length is about 0.
Needle-like TiO _x N _y fine particles coated with a silica insulating film having a thickness of 5 μm and an aspect ratio of about 10 were used together with a trace amount of spherical spacers having a diameter of 24 μm, using a silica gel raw material solution (KE1052 manufactured by Shin-Etsu Chemical Co., Ltd.). Consists of two liquids, liquid A and liquid B, with a mixing ratio of liquid A and liquid B of 1: 1 (weight ratio)
Used in the above) to prepare a suspension having a fine particle content of about 3 wt%. This was dropped onto a glass substrate with an ITO film having a thickness of 30 ± 10 nm (50 mm × 100 mm, thickness 1.1 mm) coated with silica having a thickness of about 500 nm, sandwiched between opposing glass substrates, and a voltage of 60 V was applied. The gelling reaction was allowed to proceed by heating at about 50 ° C. for 1.5 hours while applying the voltage.

When the transmittance variable element (cell) thus obtained was observed with an optical microscope, it was found that the acicular fine particles were oriented and aggregated to form a columnar aggregate perpendicular to the glass substrate. Was observed. It was found that the columnar particle aggregate had a width of about 2 to 6 μm and a length of about 20 μm, which was almost equal to the distance between the glass substrates.

One of the cell substrates was fixed and the other was connected to the probe of the actuator, and a transmittance varying device capable of controlling the displacement amount by the voltage was manufactured.

FIG. 3 shows the relationship between the relative displacement between the substrates (the displacement between the two substrates) and the visible light transmittance change width. As shown in the graph of the figure, the range of change in transmittance increases almost in proportion to the amount of relative displacement between the substrates. From this graph, when the substrate was shifted by about 35 μm, a transmittance change of about 35% was obtained. Therefore, it was confirmed that the visible light reflectance can be controlled in a wide range by forming the light reflecting film on the inner end surface of the light reflecting substrate provided on the back surface side and controlling the relative displacement between the substrates.

Further, the spectrum change was measured with the substrate shifted by about 35 μm. The result is shown in FIG. As is clear from the graph in the figure, the transmittance greatly changed over the entire visible region, and it was confirmed that this device can be used as a vehicle rearview mirror.

[0058]

As described above, the vehicle antiglare mirror of the present invention is capable of controlling the light reflectance in multiple stages by changing the relative displacement between the substrates.

Further, since the viscoelastic body, which is a dispersion medium of fine particles, is solid or semi-solid, the operation is stabilized, and the dispersion medium can be prevented from leaking and scattering at the time of breakage, and thus can be suitably used as an antiglare mirror. At the same time, its reliability and safety can be improved.

From the above, the antiglare mirror of the present invention can be suitably used as a room mirror for automobiles.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a high reflectance state of light in the case where shear stress does not exist in the antiglare mirror of the present invention.

FIG. 2 is an explanatory diagram showing a low light reflectance state when shear stress is present in the antiglare mirror of the present invention.

FIG. 3 is an explanatory diagram showing the relationship between the relative displacement amount between substrates and the transmittance change width in an elastic film containing fine particle aggregates on the front surface of the antiglare mirror of the present invention.

FIG. 4 is an explanatory view showing a change in visible transmittance of an elastic film containing fine particle aggregates on the front surface of the antiglare mirror of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixture 2 Link 3 Light-reflecting substrate 4 Reflective film 5 Reflective substrate 6 Reflecting mirror frame 7 Transparent substrate 8 Driving power source 9 Viscoelastic body 10 Fine particle aggregate 11 Intermediate film 12 Piezoelectric element driving electrode 13 Piezoelectric element

Claims (4)

[Claims] 1. A viscoelastic body including a transparent substrate, a reflective substrate, and fine particles or fine particle aggregates interposed between the both substrates and arranged in a substantially constant direction with respect to the transparent substrate, and shearing the viscoelastic body. An anti-glare mirror for a vehicle, which comprises a device exerting stress. 2. The antiglare mirror for vehicles according to claim 1, wherein the fine particles are light-absorbing fine particles. 3. The fine particles are graphite or TiO.
_x (1 ≦ x ≦ 2), TiO _x N _y (1.37 ≦ x + y ≦
1.95, 0.15 ≦ y ≦ 0.92), TiO _x coated mica (1 ≦ x ≦ 2), TiO _x N _y coated mica (1.37)
≦ x + y ≦ 1.95, 0.15 ≦ y ≦ 0.92), Ti
O _x coated glass flakes (1 ≦ x ≦ 2), TiO _x N _y coated glass flakes (1.37 ≦ x + y ≦ 1.95, 0.9.
15 ≦ y ≦ 0.92), γ-iron oxide, metal titanate,
The vehicle antiglare mirror according to claim 1 or 2, which is one or more kinds of fine particles selected from the group consisting of iron, cobalt, magnetite, barium ferrite and chromium (IV) dioxide. 4. The organic and / or inorganic material having a shear modulus (G ′) of the viscoelastic body in the range of 1 × 10 ² ≦ G ′ ≦ 1 × 10 ⁷ dyn / cm ² (measurement frequency = 1 Hz) at room temperature. The antiglare mirror for vehicles according to claim 1, which is composed of the polymer cross-linked body.