JPH0511606B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an anti-glare mirror device optimally used for automobile door mirrors, etc.

BACKGROUND ART When driving a car at night, it is often experienced that the light emitted from the headlights of a car following is reflected on the door mirrors and back mirrors, and the resulting glare becomes a hindrance to driving. In order to prevent this glare, which poses a problem for safe driving, door mirrors (side mirrors) and back mirrors with anti-glare devices are used.

FIG. 3 is a sectional view showing the structure of a typical prior art anti-glare mirror Mb.

An indium tin oxide (hereinafter referred to as ITO) transparent electrode 2a is formed on one glass substrate 1a by vacuum evaporation or sputtering, and a polyimide alignment film 3a is further formed thereon.
Do the same thing on the other glass substrate 1b.
An ITO transparent electrode 2b and an alignment film 3b are formed, both glass substrates 1a and 1b are bonded together with a sealing resin 5, and a guest-host liquid crystal is injected between them to form a liquid crystal element 4. Board 1b
A thin film of aluminum (Al) or silver (Ag) is deposited on the back surface of the mirror 6 by vacuum evaporation to form a reflecting mirror 6. In order to protect this reflecting mirror 6, a back coating film 7 is formed on the back surface of the reflecting mirror 6. The light enters the anti-glare mirror Mb from the direction indicated by the reference mark Li (from the top to the bottom in FIG. 3).

Figure 4 shows such a prior art anti-glare mirror Mb.
FIG. Light-receiving elements 21 and 22 realized by cadmium sulfide (CdS), phototransistors, photodiodes, etc.
Among them, the first light receiving element 21 detects the brightness of the light Li incident on the anti-glare mirror Mb, converts it into an electrical signal, and inputs the output to one input terminal of the light amount comparison circuit 12 via the line l1. do. The second light receiving element 22 detects the brightness on the side opposite to the first light receiving element 21 and inputs it to the other terminal of the light amount comparison circuit 12 via line l2. The light amount comparison circuit 12 compares the light amounts detected by the light receiving elements 21 and 22, and when the difference in light amount exceeds a preset value, it determines that the light is dazzling and sends the judgment output to the switching circuit 11 via the line l4. Derive.

ITO transparent electrode 2 formed on anti-glare mirror Mb
The output of a square wave generator 10 for driving the liquid crystal element 4 is applied between a and 2b during driving, so that during normal driving such as during the daytime, the liquid crystal element 4 is in a transparent state and is not protected. The glare mirror Mb functions as a general door mirror (side mirror). While driving at night or in a tunnel, if the difference in the amount of light received by the light receiving elements 21 and 22 exceeds a certain value as described above,
The switching circuit 11 stops the operation of the liquid crystal driving square wave generator 10 based on the judgment output of the light amount comparison circuit 12, and stops the driving of the liquid crystal element 4. As a result, the liquid crystal element 4 becomes inactive, and the direction of molecular alignment of the guest dye contained in the liquid crystal element 4 is angularly displaced, so that it becomes parallel to the mirror surface of the reflecting mirror 6, so that it is exposed to the anti-glare mirror Mb from behind. Approximately 1/3 of the incident light, which is reflected by the reflecting mirror 6 and exits the anti-glare mirror Mb, is absorbed by the guest dye molecules within the liquid crystal element 4, thereby achieving an anti-glare effect.

Problems to be Solved by the Invention However, such anti-glare mirrors according to the prior art are exposed to sunlight during the day and absorb light in the short wavelength region (ultraviolet rays) contained in the sunlight, causing liquid crystal and guest pigment characteristics to deteriorate. This causes undesirable results such as an increase in current consumption, a decrease in the ratio of reflectance in normal conditions to reflectance in anti-glare conditions, and fading of color, which impairs its value as an anti-glare mirror. Further, in such prior art, the two light receiving elements had to be installed separately from the anti-glare mirror, making installation and wiring work troublesome. Therefore, it is desirable to have an anti-glare mirror device that is not affected by short-wavelength light such as ultraviolet rays even when exposed to sunlight for a long period of time, and that does not cause property deterioration of the liquid crystal or guest dye even under strong light irradiation. It had been.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an anti-glare mirror device which eliminates the above-mentioned problems and which does not cause characteristic deterioration under an environment of strong light irradiation.

Means for Solving the Problems The present invention includes a reflecting mirror, a transmissive liquid crystal element disposed in front of the reflecting mirror,
A semiconductor thin film layer is placed in front of the liquid crystal element, has light shielding properties in the short wavelength region, and derives an electrical signal representing the amount of light received; a light receiving element detects ambient brightness; and an output from the semiconductor thin film layer. , when there is a large difference between the amount of light incident on the semiconductor thin film layer from the front in response to the output from the light receiving element and the amount of light received by the light receiving element, a voltage is applied to the liquid crystal element to reduce the amount of transmitted light. This is an anti-glare mirror device characterized by comprising: means for applying .

Function The anti-glare mirror device according to the present invention performs stable anti-glare operation without causing deterioration of the characteristics of the liquid crystal element even under irradiation with strong light such as sunlight.

Embodiment FIG. 1 is a sectional view showing the structure of an anti-glare mirror Ma according to an embodiment of the present invention, and FIG. 2 is a block diagram for explaining the operation of an embodiment of the present invention.

With reference to FIGS. 1 and 2, glass substrate 1
a, a first ITO transparent electrode 9, a semiconductor thin film layer 8, and a first ITO transparent electrode 9;
A 2ITO transparent electrode 2a and a polyimide alignment film 3a are formed in this order, and the alignment film 3a is in contact with the liquid crystal element 4. The structure of the semiconductor thin film layer formed on the glass substrates 1b, which are placed facing each other with the liquid crystal element 4 in between, will be described later.

What should be noted in the present invention is the glass substrate 1a
The first ITO transparent electrode 9 formed above and the semiconductor thin film layer 8 formed overlying the first ITO transparent electrode 9 serve the function of the first light receiving element 21 described in the prior art section, that is, as a glare detection sensor. It also has the function of a light blocking filter that absorbs light in the short wavelength range such as ultraviolet rays. Next, a method for manufacturing the anti-glare mirror Ma according to this embodiment will be explained.

A first ITO transparent electrode 9 is formed on the glass substrate 1a by vacuum evaporation or sputtering. This first ITO transparent electrode 9 is an electrode for applying a voltage to a glare sensing sensor described below and a semiconductor thin film layer 8 having a light shielding property against light in a short wavelength region such as ultraviolet rays.

A semiconductor thin film layer 8 such as CdS or amorphous silicon (hereinafter referred to as α-Si) is deposited on the first ITO transparent electrode 9 by a vacuum evaporation method or a plasma chemical vapor deposition (hereinafter referred to as CVD) method. form. These CdS or α-Si
The semiconductor thin film layer 8, such as It is a semiconductor thin film with a voltage of 2.5 to 2.8 eV. In addition to the method described above, the CdS thin film can also be formed by a printing method, but after printing, it can be formed at 300°C in a vacuum or in an argon gas flow.
An annealing process of about 30 minutes is required.

A second ITO transparent electrode 2a is formed on the semiconductor thin film layer 8 by vacuum evaporation or sputtering, and a polyimide alignment film 3a is further formed thereon by a printing method.

The third ITO transparent electrode 2b and polyimide alignment film 3b formed on the other glass substrate 1b are as described above.
It is formed in the same manner as the ITO transparent electrode 2a and the polyimide alignment film 3a. The thus formed glass substrates 1a and 1b are opposed to each other and bonded together with a sealing resin 5, and a guest-host liquid crystal is injected to form a liquid crystal element 4. Finally, to form the reflecting mirror 6, aluminum (Al) or silver (Ag) is deposited on the back surface of the glass substrate 1b by a vacuum deposition method.
After forming the reflecting mirror 6, a back coating film 7 for protecting the mirror surface is formed on the back surface of the reflecting mirror 6.

Next, the operation of this embodiment will be explained with reference to FIG. A DC power supply 14 is connected between the first ITO transparent electrode 9 and the second ITO transparent electrode 2a sandwiching the semiconductor thin film layer 8.
are connected via a resistor 15. When the headlight light of the following vehicle enters the anti-glare mirror Ma, the photoconductivity of the semiconductor thin film layer 8 increases, and the current flowing through the resistor 15 increases. This current increase is the output voltage
V ₁ increases, and the output voltage V ₁ is the light intensity comparison circuit 1.
It is input to one input terminal of 2. The other input terminal of the light amount comparison circuit 12 receives the output of a light receiving element 13 as a sensor that detects the amount of light surrounding the driving vehicle. The light receiving element 13 is arranged on the opposite side from the anti-glare mirror Ma, that is, toward the front of the vehicle. While the prior art requires at least two light receiving elements facing the front and rear of the vehicle, in this embodiment only one light receiving element is required.

The light intensity of the headlights of the rear car from a position about 5 m away from the anti-glare mirror Ma is about 5 mW/cm ² , and all of this light is absorbed by the CdS and α-Si forming the semiconductor thin film layer 8. Assuming that it is absorbed, the photoconductivity of the semiconductor thin film layer 8 at this time is from 10 ^-8 (Ω cm) ^-1 in the dark to 10 ^-4 to 10 ^-5
(Ω・cm) ^-1 and 10 It increases by more than ³ times. As mentioned above, since the optical absorption edge of the semiconductor thin film layer 8 is 2.5 to 2.8 eV, most of the light passes through the semiconductor thin film layer 8, but the amount of light that is captured and absorbed by the semiconductor thin film layer 8 is incident. Even if it is estimated to be 1/100 of light, the amount of absorbed light and the amount of increase in photoconductivity are almost proportional, so
It can be seen that the photoconductivity increases by about 10 to 100 times when irradiated with glare, indicating that it has the sensitivity required as a glare detection sensor. Referring again to FIG. 2, the light amount comparison circuit 12 sends a judgment output to the switching circuit 11 via line l4 when the amount of light irradiated from behind is greater than the amount of ambient light and exceeds a preset value. Derive. As a result, the switching circuit 11 stops the operation of the liquid crystal driving square wave generator 10, makes the liquid crystal element 4 inactive, and puts it into an anti-glare operating state.

In this embodiment, the door mirror (side mirror) is an anti-glare mirror, but it is not limited to the anti-glare mirror. Of course, the present invention can also be applied to fender mirrors. Since the light-receiving element 13 facing forward can be used for these door mirrors (side mirrors), back mirrors, or fender mirrors, only one light-receiving element 13 needs to be prepared, and the installation wiring is also simple.

Furthermore, although in this embodiment the anti-glare mirror Ma is set in only two states, the normal state and the anti-glare state, by the light amount comparison circuit, the anti-glare state can be changed sequentially by adjusting the waveform and voltage of the liquid crystal drive. You can do it like this.

Effects As described above, according to the present invention, a glare detection sensor and two functions for absorbing and blocking light in the short wavelength region such as ultraviolet rays are provided further in front of the liquid crystal element placed in front of the reflecting mirror. By providing a semiconductor thin film layer, only one light-receiving element is required to detect the brightness of the surrounding environment, and even if exposed to sunlight for a long period of time, light in the short wavelength region such as ultraviolet rays will not be transmitted. Since it is captured and absorbed by the semiconductor thin film layer, deterioration of the characteristics of the liquid crystal element and the guest dye contained therein is prevented.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an embodiment of the present invention, Fig. 2 is a block diagram for explaining the operation, Fig. 3 is a sectional view of the prior art, and Fig. 4 is a sectional view for explaining the operation of the prior art. FIG. 1a, 1b...Glass substrate, 2a, 2b, 9...
...ITO transparent electrode, 3a, 3b...polyimide alignment film, 4...liquid crystal element, 5...sealing resin, 6...
Reflector, 7... Back coating film, 8... Semiconductor thin film layer, 10... Square wave generator for driving liquid crystal, 11...
Switching circuit, 12...Light amount comparison circuit, 1
3, 21, 22... Light receiving element, Ma, Mb... Anti-glare mirror.

Claims (1)

[Claims] 1. A reflecting mirror, a transmissive liquid crystal element disposed in front of the reflecting mirror,
A semiconductor thin film layer is placed in front of the liquid crystal element, has light shielding properties in the short wavelength region, and derives an electrical signal representing the amount of light received; a light receiving element detects ambient brightness; and an output from the semiconductor thin film layer. In response to the output from the light receiving element, when there is a large difference between the amount of light incident on the semiconductor thin film layer from the front and the amount of light received by the light receiving element, a voltage is applied to the liquid crystal element to reduce the amount of transmitted light. An anti-glare mirror device comprising: means for applying voltage;