JPS60262132A - Antidazzle type reflection mirror for automobile - Google Patents

Abstract

PURPOSE:To generate the change in color in the stage of preventing dazzle and not preventing dazzle by forming a dielectric film having the refractive index higher than the refractive index of a guest/host (G/H) liquid crystal on the metallic reflecting surface of an antidazzle type reflection mirror provided with the G/H liquid crystal layer on the front surface of the metallic surface to be formed as a reflecting surface. CONSTITUTION:A metallic film 2 is formed on substrate glass 1 to provide a reflecting film. The high refractive-index transparent dielectric film 3 consisting of TiO2, etc. is formed thereon to a prescribed thickness. The low-refractive-index transparent dielectric film 4 consisting of SiO2, etc. is further provided thereon to a prescribed thickness. The film 4 acts to intensity coloration by the liquid crystal by the light interference with the oriented film. The phase transfer type positive display G/H liquid crystal phase 5 which is transparent when no electric field is applied thereto and induces the absorption by a dye when the electric field is applied thereto out of the G/H liquid cystals mixed with the liquid crystal and dichromatic dye is provided thereon and further an oriented layer 6, transparent electrode 7 for orienting the liquid crystal and glass 8 for holding the liquid crystal are provided thereon. Electric power for driving the liquid crystal from a power source 10 is switched 9 to the film 2 and the electrode 7. The color of the reflected light is thus changed in the stage of preventing dazzle and not preventing dazzle so that the reflection mirror is made easy for driving.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an anti-glare reflector for automobiles, including a rear-view mirror,
It can be applied to a reflecting mirror such as a Zide mirror.

(Prior Art) Most conventional automobile reflectors are made by vapor-depositing aluminum on a glass substrate, and have a high reflectance of 80 to 90% and flat spectral characteristics.

For this reason, at night, when illuminated by the lights of a following vehicle, the vehicle tends to be dazzled.

On the other hand, as shown in Japanese Patent Publication No. 48-35384 entitled "Automatically Dimming Rearview Mirror," there is a system that uses liquid crystal to provide antiglare. Various types of this type have been proposed in addition to the ones mentioned above, but all of them simply provide anti-glare, so they color the reflected light when anti-glare or when not anti-glare. It did not have a function to enhance fashionability.

(Problems to be Solved by the Invention) The present invention has been made in view of the above-mentioned problems, and provides an anti-glare reflector using a liquid crystal, in which reflected light is colored during anti-glare and non-anti-glare states, and The hue of the coloring is changed depending on whether it is dazzling or not.

(Structure of the Invention) The anti-glare reflector for automobiles of the present invention uses a guest host liquid crystal (hereinafter referred to as G/H liquid crystal) as a liquid crystal, and the G/H
It is characterized in that a high refractive index dielectric film having a higher refractive index than the G/H liquid crystal is formed between the liquid crystal and the metal film forming the reflective surface and on the metal film.

(Function) In the above anti-glare reflector for automobiles, G
/H Light from the front that has passed through the liquid crystal causes optical interference due to the action of the high refractive index dielectric film and the metal film, and the reflected light is colored. Furthermore, during anti-glare mode, the reflected light is colored in a different hue from that during non-glare mode due to the light absorption effect of the pigment of the G/H liquid crystal.

(Effect of the invention) Since the present invention is constructed and operates as described above,
While anti-glare is performed using liquid crystal, the reflected light is colored with different hues between non-anti-glare and anti-glare states, and has the excellent effect of improving the fashionability of the reflecting mirror.

(Example) Hereinafter, an example of the present invention shown in the drawings will be described. 1st
The figure is a sectional view showing a first embodiment of the present invention. A metal film 2 made of, for example, a nickel-chromium alloy is provided on one surface of the substrate glass 1, which serves both as a light reflecting surface and as an alignment electrode for liquid crystal. The thickness of the metal film 2 may be as long as it is thick enough not to transmit light (approximately 1000 Å or more). On the metal film 2, for example, T i O2
A high refractive index transparent dielectric film 3 consisting of is provided with a predetermined film thickness, and on top of that, a film that serves both as an alignment film for the liquid crystal and a role of intensifying coloring due to optical interference, for example,
A low refractive index transparent dielectric film 4 made of SiO2 is provided with a predetermined thickness. On top of that, there is a well-known phase transition in G/H liquid crystal, which is a mixture of liquid crystal and dichroic dye, in which light is transmitted when no electric field is applied, and absorption by the dye occurs when an electric field is applied. A type positive display G/H liquid crystal N5 is provided. Thereon, an alignment film 6 made of, for example, S i 02, a transparent electrode for liquid crystal alignment 7 made of [TO, and a liquid crystal holding glass 8 are provided in this order.

The metal film 2 and the transparent electrode 7 are connected to a power source 10 via a switch 9.
It is connected to the LCD and can supply the voltage necessary to drive the liquid crystal.

The operation of the above configuration will be explained. First, G/
When no voltage is applied to the H liquid crystal layer 5, the G/H liquid crystal layer 5 transmits light. Figure 1: The light coming from above is G/
The light passes through the H liquid crystal M5, is reflected by the metal film 2, and returns to the incident direction, but at this time, the presence of the transparent dielectric film 3 and the alignment film 4 causes optical interference, and the reflected light is colored.

The color tone of the reflected light is mainly determined by the thickness of the transparent dielectric film 3.

FIG. 2 shows the change in color tone when the thickness of the transparent dielectric film 3 is changed while the thickness of the alignment film 4 is kept constant at 850 people.

FIG. 2 shows the relationship between the thickness of the transparent dielectric thin film 3 and the color tone.
The color tone of the reflected light when the standard light C defined by C is perpendicularly incident is expressed by the chromaticity coordinates. In this figure 2, the chromaticity coordinates are X or red component, Y is green component, 1-(
Roughly speaking, the area G surrounded by the dotted line in Figure 2 is green, the area Y is yellow, the area R is red, the area ■ is purple, and the area B is blue'. , and the color between each area is the intermediate color. As is clear from FIG. 2, any color tone can be obtained by selecting an appropriate film thickness.

Since the light passes through the glass 8, the transparent dielectric film 7, and the alignment film 6 and enters the G/H liquid crystal layer 5, light interference in this area also has a reflective effect (although the glass 8, the transparent dielectric film 7, and the alignment film 6 Since the difference in the refractive index of the body film 7, the alignment film 6, and the G/H liquid crystal 5 is not so large, interference coloring in this part can be almost ignored.For example, the transparent dielectric film 7 is exposed to 750 people, Orientation film 6
The spectral transmittance when the number of people is 1900 is as shown in Fig. 3, and it can be said that the transmittance characteristics are almost flat. This transmission characteristic does not change significantly even if the film thickness changes.

Here, as an example, in FIG. 1, the transparent dielectric l1ll! FIG. 4 shows the reflection characteristics when the film thickness of No. 3 is 880 mm. The reflection maximum is in the blue region, and it can be said that it is a blue mirror when no voltage is applied to the G/H liquid crystal layer 5. Since human visibility reaches its maximum around 5,500 people,
The luminous reflectance at this time is about 44%.

At night, when you receive the lights of a following vehicle,
Turn switch 9 ONL and G when sunlight enters from the rear.
/H A voltage is applied to the liquid crystal layer 5.

Then, the nematic phase melts into a cholesteric phase, and absorption occurs due to the dichroic dye. For example, if an anthraquinone dye with a maximum absorption wavelength of 55 seconds, o is used as a dichroic dye, its absorption properties are not shown in Figure 5, so the reflection characteristics of the reflector are as shown in Figure 6. become that way. When compared with FIG. 4, which shows the reflection characteristics when no voltage is applied, the reflectance is low near 5550, where human visibility is the maximum, and the luminous reflectance is about 11%.

With this level of reflectance, you won't feel dazzled by the lights of cars behind you or the sun. It can also be seen that the reflection region has also moved to the shorter wavelength side, and the color tone has changed to a color closer to purple.

I mentioned one example above, but transparent dielectrics!・：゛ Various color tone combinations can be obtained by selecting the thickness of the film 3 and the type of dichroic dye.

The switch 9 may simply be a manual type, but it is more convenient to use an automatic type using an optical switch. FIG. 7 shows its block diagram. Reference numeral 11 is the reflecting mirror shown in FIG. 1, and 12 is a housing in which this is housed. The connection between the liquid crystal drive power source 10 and the reflecting mirror 11 is opened and closed by a switch circuit 13. The switch circuit 13 is operated by the output of a division circuit 14 that divides the outputs of the two light receivers 15a815b. Two light receivers 15a
, 15b is provided to detect glare felt by human eyes. Human eyes do not perceive a certain light source as being very dazzling when the surroundings are bright, but they perceive it as extremely dazzling when the surroundings are dark.

That is, one light receiver 15a detects the surrounding brightness, the other light receiver 15b detects the rear brightness, and the output ratio is above a certain level, that is, the rear brightness is detected with respect to the surrounding brightness. When the brightness of the screen reaches a certain level, the anti-glare function is activated. A detailed circuit of this device is shown in FIG. 16 is an analog computing unit (e.g. CR-BOX!
! JLXO31), 17a, 17b, and 17c are operational amplifiers (eg, μA74]), and 18 is a relay. If the output of the divider circuit 14 is higher than the reference voltage V, the operational amplifier 17
The output of a becomes the power supply voltage and drives the relay 18. Therefore, upon receiving power supply from the liquid crystal drive power source 10, the reflecting mirror 11 is turned on. On the other hand, if the output of the divider circuit 14 is lower than the reference voltage (2), that is, if the ambient brightness and the rear brightness are approximately the same, the output of the operational amplifier 17a will be approximately O, and the reflecting mirror 11 will be in the OFF state. The two light receivers 15a and 15b can be mounted anywhere as long as they can detect the rear light and the surrounding light other than the rear. It can be installed horizontally, and for detecting rear light, it can be installed backwards on a part of the mirror or rear window.

Note that the reflecting mirror according to the present invention is effective even when used as a fender mirror, a door mirror, or a room mirror.

Further, in this example, a nickel-chromium alloy was used as the metal film, TiO2 was used as the high refractive index transparent dielectric, and 5i02 was used as the low refractive index transparent dielectric, but the present invention is not limited thereto. Metals such as chromium, aluminum, nickel, and titanium that provide the necessary reflectance; high refractive index dielectrics that have a higher refractive index than G/H liquid crystals such as ZrO2 and Ce'02; and Mg
A low refractive index dielectric having a lower refractive index than the G/H liquid crystal such as F2 may be used.

Next, a second embodiment of the present invention will be described. FIG. 9 is a sectional view thereof. In the first embodiment, a low refractive index transparent dielectric film 4 was provided on the high refractive index transparent dielectric film 3 as an alignment film, but in this embodiment, this low refractive index transparent dielectric film 4 is omitted. Therefore, for example, the high refractive index transparent dielectric film 3 made of TiO2 has a function as an alignment film. FIG. 10 shows the change in hue of reflected light when the thickness of the high refractive index transparent dielectric body film 3 is changed.

Comparing this with Figure 2, the trajectory is smaller, and the first
It can be seen that only lighter colors can be expressed than in the case of the example. This is because the alignment film 4, which had the role of enhancing the interference effect, was removed, and the undulations of the spectral reflectance became smaller. Therefore, although the color becomes pale when no voltage is applied to the G/H liquid crystal, the same effects as the first embodiment are obtained in terms of anti-glare effect and color change when voltage is applied.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the first embodiment of the invention, and FIG. 2 is a cross-sectional view showing the first embodiment of the invention.
Characteristic diagrams showing the relationship between the film thickness and color tone of the high refractive index transparent dielectric film in Examples, Figures 3, 4, and 6 are characteristic diagrams of spectral transmittance used to explain the operation. A characteristic diagram showing the absorption characteristics of anthraquinone dyes, Fig. 7 is a block diagram of an anti-glare driving circuit for a reflecting mirror, Fig. 8 is a detailed circuit diagram of the circuit shown in Fig. 7, and Fig. 9 is a block diagram of an anti-glare driving circuit for a reflecting mirror. A sectional view showing the second embodiment, and FIG. 10 are characteristic diagrams showing the relationship between the film thickness and color tone of the high refractive index dielectric film in the second embodiment. 2... Metal film, 3... High refractive index transparent dielectric film, 5...
...G/H liquid crystal layer. Figure 1 ↓ Figure 2 Figure 3 Figure 5 100L xioo. Fig. 6 j A view (person, X100O Fig. 7 2 Fig. 8

Claims (1)

[Scope of Claims] An anti-glare reflector for an automobile, comprising a guest-host liquid crystal layer provided on the front surface of a metal film forming a reflective surface, wherein the metal film is provided between the metal film and the guest-host liquid crystal layer. An anti-glare reflector for an automobile, characterized in that a high refractive index dielectric film having a higher refractive index than the guest-host liquid crystal is formed.