JPH0588144A - Liquid crystal antidazzle mirror - Google Patents

Abstract

PURPOSE:To obtain the liquid crystal antidazzle mirror which is highly reliable and is economically excellent in terms of electric power consumption, etc., by providing a liquid crystal element which is made into a light scattering state when impressed with a voltage and into a light transparent state when not impressed with the voltage at least on the part of the surface of a mirror body. CONSTITUTION:This liquid crystal antidazzle mirror is constituted by laminating and integrating the liquid crystal element L having the structure holding a high-polymer liquid crystal composite film 1 by a pair of transparent base materials 3, 3 formed with transparent electrodes 2, 2 on one surface to the mirror body M via an adhesive layer 4. Namely, the liquid crystal element L which is made into the light scattering when impressed with the voltage and into the light transparent state when not impressed with the voltage is provided on the surface of the mirror body M. Such crystal L is produced by casting and applying a soln. prepd. by dissolving a matrix high polymer and a liquid crystal material into a suitable solvent on the surface of the one transparent base material 3 and drying the coating to form the high-polymer liquid crystal composite film 1, then superposing the other transparent base material 3 on this high-polymer liquid crystal composite film 1. Then, the mirror is prevented from being made hardly visible by a fluctuation in the impressed voltage or the stop thereof in the antidazzle state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antiglare mirror which is preferably used as a vehicle-mounted mirror such as a rearview mirror, and more particularly to a liquid crystal antiglare mirror which utilizes a dimming effect of a liquid crystal element. Is.

[0002]

2. Description of the Related Art As a conventional liquid crystal antiglare mirror, for example, a pair of transparent substrates provided with a transparent electrode having a liquid crystal layer in which a liquid crystal substance is dispersed and held in a solidified resin matrix. A liquid crystal element (light control material) having a structure sandwiched between the two is superposed on a mirror body (actually, it is 2-756
No. 01), low birefringence including a polychromatic dye,
A combination of a liquid crystal element in which a lump or a granular material of an operationally nematic liquid crystal is confined in a confinement medium composed of a transparent resin or the like in a state in which its natural structure is distorted, and a mirror body (JP-A-62-62 No. 283316).

The former liquid crystal anti-glare mirror utilizes the fact that the liquid crystal layer is in a light transmitting state when a voltage is applied and is in a light scattering state when no voltage is applied, which makes use of the light reflectance of the mirror body. To adjust. Further, the latter liquid crystal anti-glare mirror, when a voltage is applied to the lumps or particles of the liquid crystal, the liquid crystal changes from the distorted state as described above to a neatly aligned state, and in the distorted state of the liquid crystal. The polychromatic dye contained in the lumps or granules of liquid crystal absorbs a large amount of light, but the light absorption is minimal when the liquid crystal is neatly aligned, and the light reflectance of the mirror body is adjusted. To do.

However, in-vehicle mirrors and the like are often used continuously in a non-glare state (transparent state) during the day, and therefore, like the conventional liquid crystal glare mirrors described above, the light from the liquid crystal element is not used. There is a problem in that it is economically unfavorable from the viewpoint of power consumption that the liquid crystal element needs to be continuously applied with a voltage in order to maintain the transmission state and maintain the light reflectance of the mirror body at the maximum state. ..

Further, when the applied voltage fluctuates, the light transmission state of the liquid crystal element varies, and the mirror becomes difficult to see, and when the applied voltage is stopped due to some accident, the liquid crystal element becomes in a light scattering state. The conventional liquid crystal anti-glare mirror described above has a problem in terms of reliability, such as a risk that the mirror cannot be seen at all. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above technical problems and to provide a liquid crystal antiglare mirror which is excellent in reliability and economically excellent in terms of power consumption and the like.

[0006]

In order to solve the above-mentioned problems, the liquid crystal antiglare mirror of the present invention has a liquid crystal element which is in a light-scattering state when a voltage is applied and is in a light-transmitting state when no voltage is applied. It is characterized in that it is provided at least in part.
As the liquid crystal element, one provided with a composite film (hereinafter referred to as “polymer / liquid crystal composite film”) having a structure in which liquid crystal is filled in the pores of a matrix polymer having a sponge structure is preferably used. In this liquid crystal element, the liquid crystal molecules in the pores are in a random state when no voltage is applied, and when a voltage is applied, Δε> 0 [where Δε is a dielectric anisotropy,
formula:

[0007]

[Equation 1]

It is represented by (note that

[0009]

[Outer 1]

Is the dielectric constant in the molecular axis direction,

[0011]

[Outside 2]

Indicates the dielectric constant in the direction orthogonal to the molecular axis)], the liquid crystal molecules are aligned in the direction of the electric field by the electro-optical effect. Normally, when no voltage is applied and the liquid crystal molecules in the pores are in a random state, the incident light is scattered and the polymer / liquid crystal composite film is in an opaque state. When it is oriented to, it becomes a light transmitting state. However, according to the study by the present inventors, the refractive index of the liquid crystal material and the refractive index of the polymer are

[0013]

[Equation 2]

[Wherein η _P represents the refractive index of the polymer and η _LC represents the refractive index of the liquid crystal material], and when no voltage is applied,

[0015]

[Equation 3]

[Wherein η _P is the refractive index of the polymer as described above,

[0017]

[Outside 3]

Is the refractive index of the liquid crystal in the molecular axis direction,

[0019]

[Outside 4]

Is the refractive index in the direction orthogonal to the molecular axis of the liquid crystal], the polymer type and the liquid crystal type are selected and the composition is designed. Conversely, the polymer / liquid crystal composite film is formed. ,
It has been found that a light scattering state can be achieved when a voltage is applied, and a light transmission state can be achieved when no voltage is applied. That is, in such a liquid crystal element, when a voltage is applied, the refractive index of the matrix polymer and the liquid crystal become inconsistent, and light is diffusely reflected at the interface between the two, resulting in a light scattering state. The refractive indexes of the two coincide with each other, and the light is transmitted.

Therefore, the liquid crystal anti-glare mirror of the present invention equipped with the above liquid crystal element has high reliability and high reliability in the non-anti-glare state without the fear that the mirror becomes difficult to see due to fluctuations or stoppage of the applied voltage. High reflectance can be obtained in a dazzling state. Further, since the liquid crystal anti-glare mirror of the present invention maintains the non-anti-glare state when no voltage is applied as described above, it is continuously used in the non-anti-glare state (transparent state) during the day, for example. In this case, since it is not necessary to apply a voltage, it becomes economically superior in terms of power consumption and the like.

Moreover, since the polymer / liquid crystal composite film contains a matrix polymer, when it is filled between supports, it has a self-supporting property such that the cell spacing can be maintained without using a spacer or the like. There is also an advantage that it can be done.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings showing embodiments. FIG. 1 is a sectional view showing an embodiment of the liquid crystal antiglare mirror of the present invention. As shown in the figure, the liquid crystal antiglare mirror of this embodiment has a structure in which a polymer / liquid crystal composite film 1 is sandwiched between a pair of transparent base materials 3 and 3 having transparent electrodes 2 and 2 formed on one surface. The liquid crystal element L is laminated and integrated with the mirror body M via the adhesive layer 4.

As the polymer / liquid crystal composite film 1, the above-mentioned composite film composed of a matrix polymer and a liquid crystal material is used. As the matrix polymer, various polymer materials can be used as long as they are transparent. For example, acrylic resins such as polyacrylic acid ester and polymethacrylic acid ester, fumarate-based resins such as polydiisopropyl fumarate, and diallyl phthalate. Resin, etc.
Among these, those having a refractive index satisfying the above-mentioned conditions are appropriately selected and used.

As the liquid crystal material, nematic liquid crystal or the like used in ordinary liquid crystal display elements is preferably used, and among them, those having a refractive index satisfying the above-mentioned conditions are appropriately selected and used. It The nematic liquid crystal is not particularly limited, but it is preferable to use one having a large dielectric anisotropy Δε in order to obtain good characteristics.

Incidentally, an appropriate amount of dichroic dye may be added to the polymer / liquid crystal composite film 1 in order to make the antiglare effect in the light scattering state more effective. Further, since the polymer / liquid crystal composite film 1 contains a matrix polymer, as described above, it has self-supporting property without using a spacer or the like, but if necessary, glass beads,
Spacers such as resin particles can also be blended.

Examples of the transparent substrate 3 include transparent plastic films, plastic plates, glass plates and the like. As the transparent electrode 2 formed on the surface of the transparent base material 3, thin films made of various conventionally known transparent conductive materials such as ITO (indium tin oxide) film can be used. A drive device 5 including a power source 5a and a switch 5b is connected between the transparent electrodes 2 and 2. The driving device 5 is used when the polymer / liquid crystal composite film 1 is brought into a light-scattering state, and as the power source 5a, a device that can generate a DC voltage or an AC voltage is used.

The polymer / liquid crystal composite film 1, the transparent electrode 2,
The liquid crystal element L composed of the transparent base material 3 is formed by casting a solution of a matrix polymer and a liquid crystal material dissolved in a suitable solvent on the surface of one transparent base material 3 and drying it to form a polymer. / Liquid crystal composite film 1 is formed, and then the other transparent substrate 3 is laminated on the polymer / liquid crystal composite film.

As the mirror M, a transparent substrate M such as a glass plate is used.
An ordinary mirror having a light reflecting film (not shown) formed on the back surface of the No. 1 is used. As the adhesive layer 4 for adhering the liquid crystal element L and the mirror body M, an adhesive which is suitable for adhering the both and is transparent when cured or solidified so as not to prevent light transmission is used.

The liquid crystal anti-glare mirror having the above-described structure can be manufactured by using a normal mirror as the mirror body M and simply bonding the liquid crystal element L to the surface of the mirror M with an adhesive, which is advantageous in that the manufacturing is easy. is there. Next, a liquid crystal anti-glare mirror of another embodiment shown in FIG. 2 will be described. As shown in the figure,
In the liquid crystal antiglare mirror of this embodiment, the polymer / liquid crystal composite film 1 is sandwiched by a transparent substrate 3 having a transparent electrode 2 formed on one surface and a mirror body M having a metal electrode 6 formed on the surface thereof. By doing so, the liquid crystal element L integrated with the mirror body M is configured. The metal electrode 6 also serves as a light reflecting film of the mirror body M.

According to the above construction, the metal electrode 6 and the mirror M
Serves as one of the electrodes sandwiching the polymer / liquid crystal composite film 1 and the base material, and the metal electrode 6 serves as the light reflecting film of the mirror body M, so that the total number of layers can be reduced. The advantage is that the structure of the liquid crystal antiglare mirror can be simplified. Although the polymer / liquid crystal composite film 1 is a single layer in both of the above-mentioned examples, a plurality of layers may be laminated to increase the contrast.

In the embodiment shown in FIG. 2, the mirror M is provided with the metal electrode 6 also serving as a light reflection film on the surface thereof, but the mirror M has a light reflection film on the back surface. A transparent electrode may be formed on the surface of the formed ordinary mirror. In addition, various design changes can be made to the layer structure, the shape, and the like without departing from the scope of the invention.

Next, a specific example will be described in more detail. * Specific Example 1 40 parts by weight of diallyl phthalate resin (η _P = 1.5252, manufactured by NOF CORPORATION) as a matrix polymer,
Liquid crystal (Δη = 0.216,

[0034]

[Outside 5]

= 1.608,

[0036]

[Outside 6]

= 1.4867, M manufactured by Merck Japan Co., Ltd.
60902 parts by weight of J90217) was dissolved in dichloromethane to obtain a coating solution having a concentration of 20%. This coating solution was applied by a bar coating method on a transparent substrate having an ITO film as a transparent electrode on the surface and dried at room temperature for 30 minutes to form a polymer / liquid crystal composite film, and then the composite film A mirror body provided with a Cr electrode also serving as a light reflection film was superposed on the surface, and a liquid crystal anti-glare mirror having a layer structure shown in FIG. * Specific Example 2 The coating solution prepared in Specific Example 1 was applied by a bar coating method on a transparent substrate having an ITO film as a transparent electrode on its surface, and dried at room temperature for 30 minutes to form a polymer / liquid crystal composite. After forming the film, another transparent substrate with an ITO film was laminated on the surface of this composite film to form a liquid crystal element.

Next, the above liquid crystal element was adhered to the surface of the mirror body having the light reflection film on the back surface by using an optical adhesive (trade name "lens bond" manufactured by Applied Photonics Laboratory Co., Ltd.), A heat treatment was performed at 70 ° C. for 70 minutes to cure the adhesive, and a liquid crystal antiglare mirror having a layer structure shown in FIG. 1 in which the liquid crystal element L and the mirror body M were laminated and integrated by the adhesive layer 4 was produced. ..

As shown in FIG. 1 or FIG. 2, a power source 5 is provided between both electrodes of the liquid crystal antiglare mirror manufactured in the above-mentioned specific examples 1 and 2.
When the driving device 5 including the switch a and the switch 5b is connected and an AC voltage (60 V) is applied, each of them is about 10
The liquid crystal element became a light scattering state at 0 ms, and when the voltage application was stopped, the liquid crystal element became a light transmitting state at about 100 ms.

Therefore, the liquid crystal anti-glare mirrors of the above-mentioned specific examples 1 and 2 are irradiated with light from a He-Ne laser (wavelength 633 nm, emission light diameter 1 mmφ) as a light source, and the reflected light is received by a phototube (received light). The amount of light reflected from the liquid crystal anti-glare mirror was determined, and the light reflectance of the liquid crystal anti-glare mirror was calculated from the irradiation light amount and the reflected light amount. The results are shown in Table 1.

[0041]

[Table 1]

From the results in Table 1 above, the liquid crystal antiglare mirrors of Examples 1 and 2 are both in the antiglare state (light scattering state) when a voltage is applied and in the nonglare state (transparent state) when no voltage is applied. I knew that.

[0043]

As described in detail above, the liquid crystal antiglare mirror of the present invention is provided with a liquid crystal element that is in a light scattering state when a voltage is applied and in a light transmitting state when a voltage is not applied. In the above, there is no fear that the mirror becomes difficult to see due to fluctuations or stoppage of the applied voltage, the reliability is high, and the reflectance in the non-glare state is high and easy to see. Moreover, the liquid crystal antiglare mirror of the present invention does not need to be applied with a voltage during continuous use in a non-antiglare state (transparent state) during the day, and is economically excellent in terms of power consumption and the like. .. The liquid crystal antiglare mirror of the present invention can be suitably used particularly for vehicle-mounted mirrors such as rearview mirrors.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a liquid crystal antiglare mirror of the present invention.

FIG. 2 is a sectional view showing another embodiment of the liquid crystal antiglare mirror of the present invention.

[Explanation of symbols]

 L liquid crystal element M mirror body 1 polymer / liquid crystal composite film 2 transparent electrode 3 transparent substrate 6 metal electrode

Claims (3)

[Claims] 1. A liquid crystal antiglare mirror comprising a liquid crystal element that is in a light scattering state when a voltage is applied and is in a light transmitting state when a voltage is not applied, on at least a part of the mirror surface. 2. A liquid crystal antiglare mirror according to claim 1, wherein the liquid crystal element is constituted by sandwiching a composite film composed of a matrix polymer and liquid crystal between a pair of transparent base materials having transparent electrodes. 3. A liquid crystal device comprising a composite film composed of a matrix polymer and liquid crystal sandwiched between a mirror body having a metal electrode also serving as a light reflecting film and a transparent substrate having a transparent electrode. The liquid crystal antiglare mirror according to claim 1.