JPS60114806A - Liquid crystal antidazzling type reflector - Google Patents

Abstract

PURPOSE:To prevent the malfunction of antidazzling and to remove the lack of a reflected video by fitting a translucent mirror layer partially transmitting light to a liquid crystal element plate and detecting light transmitted through the layer by an optical sensor. CONSTITUTION:Roughly divided, a reflector consists of a fixture 1 fitting the reflector, a frame body 2 to which the fixture 1 is attached, a driving circuit 9 driving a liquid crystal element plate 50 arranged in the frame body, and the liquid crystal frame body 50 controlling the reflection factor. The liquid crystal element plate 50 is constituted by laminating a transparent glass substrate 3a, a transparent electrode layer 4a consisting of ITO, an orientation film 5a orientating liquid crystal in parallel, a liquid crystal layer 6 generating nematic liquid crystal and generating DSM, an orientation film 5b, a transparent electrode layer 4b, a transparent glass substrate 3b, and a translucent mirror layer 8 successively from the end side of the light incident side. A photodiode 10 which is an optical sensor detecting the light transmitted through the liquid crystal element plate 50 is arranged on the back part of the translucent mirror layer 8. When voltage is impressed, the liquid crystal element plate 50 generates dynamic scattering, so that the light reflection factor of the whole reflector can be electrically controlled by controlling the transmittivity of light at the liquid crystal layer by the scattering.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an anti-glare reflector whose light reflectance is electrically controlled by utilizing the electro-optical properties of liquid crystal.

INDUSTRIAL APPLICATION This invention can be utilized as a rearview mirror, such as a rearview mirror and a side mirror of a car.

When the headlights of a following vehicle or the sun's rays directly enter these reflecting mirrors, the reflectance of the light on the mirror surface is automatically reduced, thereby preventing the driver from being dazzled.

[Prior art]

Conventionally, in anti-glare anti-IA mirrors using liquid crystals, optical sensors have been installed around the outside of the reflector to detect strong light beams that enter the reflector from behind.

However, this method is against! In addition to the light that is directly incident on the J4 mirror, it also detects the light that is incident in the lateral direction, resulting in the inconvenience of providing an anti-glare effect when unnecessary. In order to improve this drawback, an optical sensor was installed inside the frame of the 64&JE to directly detect the light transmitted through the liquid crystal element, and the light was transmitted through a reflective layer provided on one end surface of the substrate of the liquid crystal element. One possible method is to use a sensor to detect the light that passes through the window. However, with this method, it is difficult to adjust the position for arranging the optical sensor, and because the reflective layer has a window, part of the reflected image may be missing, making it difficult to see the reflected image. This method requires a step of providing a light-transmitting window in the reflective layer, which increases the number of man-hours required for manufacturing.

Furthermore, the electronic circuits that drive these are generally attached to the outside, separate from the frame, making it inconvenient to handle the reflector.

[Purpose of the invention]

Therefore, the present invention has been made to improve the above-mentioned drawbacks, and provides an easy-to-handle liquid crystal anti-glare type that prevents anti-glare malfunctions, eliminates the loss of reflected images, and is integrated with a drive circuit. The purpose is to provide a calming effect without providing a reflective mirror.

[Structure of the invention]

That is, the present invention provides a liquid crystal element plate that has a semi-transparent mirror layer that transmits a portion of incident light and whose light transmittance changes by applying an electric field, and a frame that holds the liquid crystal element plate in front. a light sensor provided inside the frame body to detect light transmitted through the semi-transparent mirror layer; a light sensor provided inside the frame body to input an output signal from the light sensor; A liquid crystal anti-glare reflector comprising: a drive circuit for driving the liquid crystal element plate;

The liquid crystal element plate is a plate-shaped liquid crystal element.

As the liquid crystal element used in the present liquid crystal anti-glare reflector, any element can be used as long as it is an element whose light transmittance can be changed by application of an electric field. For example, DSM type liquid crystal elements generate dynamic scattering by applying an electric field and control the transmittance of light by scattering, and nematic liquid crystals and polarizers are used to utilize the optical rotation of light. Twisted nematic liquid crystal elements that control light transmittance, guest-host liquid crystal elements that mix liquid crystal with dichroic dye that absorbs only polarized light in one direction, and other devices that exhibit the electric field-controlled birefringence effect. Furthermore, liquid crystal elements that utilize the phase transition effect between cholesteric and nematic phases can be used.

These liquid crystal devices generally have a pair of parallel transparent glass substrates. A transparent electrode layer for applying an electric field is provided on each inner end surface of this glass substrate. This transparent electrode layer is made of indium tin oxide (ITO)
, tin dioxide ('5nO2), titanium dioxide (TiO2)
etc. can be used. On the other hand, on one end surface of the glass substrate opposite to the light incident end, there is a semi-transparent mirror layer that transmits some light and reflects most of the light. The mirror layer can be formed by depositing a metal or a non-metal to an arbitrary thickness to set an appropriate ratio of transmittance and reflectance.

For example, if the thickness of the layer to be vaporized is set to 1/4 wavelength,
Zinc sulfide (ZnS), cerium oxide (CeOz),
Titanium monide (TiO2) can be used. Also, aluminum, silver, chrome, gold, etc. are used.

In this way, a semitransparent i-layer is formed on one end surface of the glass substrate.

This semitransparent mirror layer may also serve as the transparent electrode layer provided on the inner end surface of the glass substrate described above.

The present invention further provides a frame body that holds a flat liquid crystal element plate on the front side, and a frame body that is provided inside the frame body at the rear of the semitransparent mirror layer and that transmits through the semitransparent mirror layer. It has an optical hinge that detects light.

For this optical sensor, a photoconductive element such as CdS and a photovoltaic element such as a photodiode can be used.

Further, inside the frame, a drive circuit is provided which inputs an output signal from the optical lens and drives the liquid crystal element by applying an electric field between both electrodes of the liquid crystal element in accordance with this signal. . This drive circuit is powered externally.

The seed crystal anti-glare reflector of the present invention has the above configuration 1p+.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on specific examples.

FIG. 1 is a sectional view showing the structure of a liquid crystal anti-glare reflector according to a specific embodiment of the present invention. The reflecting mirror of the non-embodiment has a mounting tool 1 that can remove the reflecting mirror, and
It consists of a frame 2 disposed on a fixture 1, a drive circuit 9 disposed inside the frame for driving a liquid crystal element plate, and a liquid crystal element plate 50 for controlling reflectance. The liquid crystal element plate 50 includes, in order from the end surface on the light incident side, a transparent glass substrate 3a1, a transparent electrode layer 4a1 made of ITO, and an alignment film 5a for aligning liquid crystals in parallel.
.

a liquid crystal layer 6 made of nematic liquid crystal that generates DSM;
It has an alignment film 5b, a transparent electrode layer 4b, a transparent glass substrate 3b, and a semi-transparent mirror layer 8. This liquid crystal element plate is configured to generate dynamic scattering by applying a voltage, and to control the transmittance of light in the liquid crystal layer by scattering, thereby electrically controlling the reflectance of light as a whole of the reflecting mirror. ing.

The thickness of the transparent electrode layers 4a and 4b used in this liquid crystal element plate was 1000 mm, and the thickness of the alignment films 5a and 5b was 1000 mm. Further, the thickness of the liquid crystal layer 6 is 10 μm. Furthermore, the translucent 11 layer 8 is made of aluminum and has a thickness of 200 mm. On the other hand, at the rear of the semi-transparent mirror layer 8, a photodiode 10, which is a light sensor that detects the light transmitted through the liquid crystal element plate 50, is installed.

This photodiode 10 is connected to a substrate 9 that holds a drive circuit 9.
It is located at 1. The drive circuit 9 is supplied with power from an on-vehicle battery via a power line 92.

FIG. 2 shows the relationship between the voltage applied to the liquid crystal element plate and the light transmittance by detecting the light transmitted through the semi-transparent mirror layer 8 in the liquid crystal anti-glare reflector of this example. It is a measurement diagram. According to this graph, when no voltage is applied, the transmittance of the liquid crystal is maximum, and the amount of light passing through the semi-transparent mirror layer 8 is about 6%. Also, when the voltage is 13V,
It can be seen that a dynamic scattering effect occurs, so that the intensity transmitted through the semi-transparent mirror layer 8 changes, and the transmittance decreases to 4%.

In this way, the intensity of light detected by the photodiode 10 differs between non-glare and anti-glare states. Since the intensity of the light detected when the glare is dimmed is lower than that when the glare is not dimmed, the drive circuit that drives the liquid crystal element plate needs to be devised.

FIG. 3 is an electrical circuit diagram that does not show the configuration of the drive circuit used in this embodiment.

The inverting input terminal of the comparator 18 receives the potential V1 at the connection point between the resistor 12 and the photodiode 10 as a detection voltage. Further, a voltage V2 divided by the resistor 13 and the resistor 14 of the battery voltage Vcc is inputted to the non-active input saw terminal of the comparator 18 as a reference voltage. On the other hand, a positive feedback resistor 17 is connected between the non-inverting input terminal and the output terminal of the comparator 18. This positive feedback resistor is provided to provide the comparator with a well-known hysteresis characteristic in its operation. Output V3 of comparator 18
is input to the 1-alternative OR circuit 19, and its output v5 is input to the transparent electrode 4a of the liquid crystal element plate 50. on the other hand,
The output v4 of the pulse oscillator 200 is input to the exclusive OR circuit 19. Further, the output V4 is also input to the transparent electrode 4b of the liquid crystal element plate 50. The pulse oscillator 200 includes CMOS inverters 23, 24, 25,
It consists of a resistor 21 and a capacitor 22 that determine the oscillation time constant.

FIG. 4 is a timing chart illustrating the operation of the drive circuit of FIG. 3. The reference potential v2 of the comparator 18 is set to Vt1 and Vt2, respectively. When the output potential V3 of the comparator 18 is at a low level, V2 is at a low potential V
At t2, when V3 is at a high level, v2 is at a high potential Vt
is set to l.

When the incident light intensity gradually increases as shown in FIG. 4(a), the potential v1 decreases as shown in FIG.
! do. Then, as shown in FIG. 4(C), the output potential V3 of the comparator 18 becomes high level at time t1. At the same time as it becomes a high level, the set value of the reference potential v2 becomes Vt1.

A voltage is applied to the liquid crystal element to cause dynamic scattering, and as a result, the incident intensity of light detected by the photodiode 10 decreases by Δl as shown in FIG. V1 increases accordingly [but,
It does not reach the reference potential Vt1.

Therefore, the output v3 of the comparator 18 remains at a high level until time t2.

On the other hand, the output \14 of the pulse oscillator 200 is shown in Fig. 4 (
As shown in d), a rectangular wave is output.

Therefore, due to the action of the exclusive OR circuit 19, the voltage V3
Only when is at a high level, the potentials v5 and 4 applied to the electrodes 4a and 4b at both ends of the liquid crystal element plate 50 have an opposite phase relationship, and the voltage applied to the liquid crystal element is
The result will be as shown in Figure (e).

That is, the liquid crystal element is driven between times t1 and t2.

Time t2 is the time when the intensity of the light incident on the reflecting mirror decreases and the voltage v1 detected by the photodiode reaches the reference potential Vt1. That is, it is the time to cancel the anti-glare effect.

In this manner, the device of this embodiment provides the comparator 18 with a history characteristic and directly detects the light transmitted through the liquid crystal element, thereby achieving an anti-glare effect that prevents anti-glare malfunctions and chattering.

〔Effect of the invention〕

In summary, the present invention provides an anti-glare reflector having a liquid crystal element plate whose light transmittance can be electrically changed, in which the liquid crystal element plate is provided with a semi-transparent mirror layer that partially transmits light. The light transmitted through this layer is detected by an optical sensor. Therefore, since the light incident on the reflecting mirror can be directly detected, accurate anti-glare can be performed. Furthermore, since the device of the present invention uses a semi-transparent mirror layer, unevenness in reflected images and missing images do not occur. Further, there is no need to adjust the position of the optical sensor and the liquid crystal element plate, and no extra steps such as providing a window on the specular reflection 19 are required. Therefore, manufacturing is easy. Further, an electronic circuit for driving the liquid crystal element plate is provided inside the frame of the reflecting mirror integrally with the optical sensor. Therefore, the reflector has the advantage of being easy to handle and attach.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of a liquid crystal anti-glare reflector according to a specific embodiment of the present invention. FIG. 2 is a graph showing the relationship between the transmittance of light passing through the semi-transparent #11 layer and the voltage applied to the liquid crystal layer in the liquid crystal anti-glare reflector of the same example. FIG. 3 is a circuit diagram showing a specific configuration of the drive circuit used in the liquid crystal anti-glare reflector of the same embodiment. FIG. 4 does not show its operation but is a timing chart. 3a, 3b...Transparent glass substrate 4a 14b...Transparent electrode layer 5a, 5b...Alignment film 6...Liquid crystal 8...Semitransparent mirror layer 9...Drive circuit 10...Photodiode 50 ...Liquid crystal element plate patent applicant Nippondenso Co., Ltd. agent Patent attorney Hirodo Okawa Patent attorney Raw materials Shudo Patent attorney Akio Maruyama

Claims (1)

[Scope of Claims] (1) A liquid crystal element plate having a semi-transparent mirror layer that transmits a portion of incident light and whose light transmittance can be changed by applying an electric field; a frame body sandwiched between the frame bodies; a photosensor provided inside the frame body to detect light transmitted through the semi-transparent mirror layer; and a photosensor provided inside the frame body to detect the output signal from the photosensor. a drive circuit for driving the liquid crystal element plate by inputting the following: