JPH0332494B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to an anti-glare mirror device, and more specifically, it has an anti-glare function by discriminating the incident light from the rear and the brightness of the surroundings at night etc. and automatically switching the mirror reflectance. This invention relates to an anti-glare mirror device. [Background of the Invention] Anti-glare mirrors for vehicles, such as rear-view mirrors, are designed to "dark" by changing the reflective surface of the mirror using a lever or switch, since the light emitted from a following vehicle dazzles the driver's eyes at night. This type of anti-glare mirror is intended to protect the driver's eyes, and there are prism-type and liquid-crystal type mirrors. For example, "Electromagnetic automatic dimming mirror"
As proposed in Publication No. 18264), the light emitted from the headlights of the following vehicle is detected, an electromagnetic circuit is driven according to the amount of detected light, and a prism mirror with two types of reflective surfaces is switched to prevent glare. A so-called prismatic type mirror that functions as an anti-glare mirror for automobiles (Japanese Patent Application Laid-Open No. 14119-1983)
As disclosed in the Japanese Patent Publication (Japanese), it detects the light emitted from the headlights of the following vehicle, drives a liquid crystal drive circuit according to the amount of detected light, and is built into the mirror surface to electrically darken the reflective surface of the mirror. There is a so-called liquid crystal type that achieves an anti-glare effect by applying power to a liquid crystal that can be used. However, in this type of conventional anti-glare mirror device, the light detection unit that detects the irradiation light from the following vehicle is composed of a light-receiving element unit or an amplifier different from the light-receiving element. The structure was such that it reacts to all types of light, outputs a detection signal to a subsequent control circuit, determines that dazzling light has been detected, and switches to an anti-glare state. Therefore, even if the light from a street light, neon light, etc. that is turned on by an AC power source is detected, the mirror will be switched to an anti-glare state with low reflectance, which will worsen the reflection conditions. Ta. [Object of the Invention] The present invention has been made in view of the problems in the prior art described above, and it is an object of the present invention to reduce the mirror reflectance of light emitted from all surrounding lights when the surroundings are dark, such as at night. To provide an anti-glare mirror device which can change mirror reflectance only when detecting light emitted from a headlight of a following vehicle. [Summary of the Invention] The anti-glare mirror device according to the present invention, when the surroundings are dark such as at night, uses the irradiation light from surrounding street lights and neon lights that are turned on by an AC power source, and the illumination light from the surrounding street lights and neon lights that are turned on by a DC power source. The mirror is equipped with a filter circuit that distinguishes it from the light emitted from the headlights of the following vehicle, and reduces the reflectance of the mirror only when it receives light emitted from the headlights of the following vehicle, thereby achieving an anti-glare effect. do. [Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a specific circuit diagram of a liquid crystal anti-glare mirror device as an example.
In the figure, 1 is a switch circuit consisting of switches SW ₁ , SW ₂ , SW ₃ and a display (light emitting element LED).
2 has a light receiving element PS ₁ that detects the surrounding brightness, an amplifier IC ₃ , and has a certain width of hysteresis, and outputs an "L" level when the received light intensity is high and exceeds a certain brightness. This is a second light detection unit for detecting ambient brightness, which is composed of a light sensor IC ₄ and a light sensor IC 4. Reference numeral 3 denotes a first light detection unit that detects the light emitted from the headlight of the following vehicle, which includes an amplifier IC ₁ that amplifies the signal detected by the light receiving element PS ₂ that detects only the light emitted from the headlight of the following vehicle; It is provided at the output section of amplifier IC ₁ , and consists of capacitors C ₆ to _{C 8} and resistors R ₂₁ to R _22. It identifies whether the received light power waveform is an AC power waveform or a DC power waveform, and detects and outputs only the DC power waveform. Filter circuit 3-1
With a certain width of hysteresis, the photodetector PS ₂
It consists of a comparison circuit IC ₂ that compares the output signal detected by the sensor with a reference signal, and is designed to detect only the light emitted from the headlight of the following vehicle. 4 is an AND circuit; 5 is a delay circuit consisting of a hazard absorption circuit, a one-shot circuit, and an OR circuit; 6 is a liquid crystal drive circuit consisting of a square wave oscillator, a T-type flip-flop circuit, and an EXOR circuit; 7
is a constant voltage circuit to keep the power supply voltage fluctuation constant,
8 is a power supply reverse connection protection circuit (diode) that protects the circuit from reverse connection of power supply polarity. In addition, in the figure,
IC ₅ is an AND circuit element, IC ₇ and IC ₉ are OR circuit elements,
IC ₆ and IC ₈ are buffer circuit elements, IC ₁₀ to _{IC 13} are inverter circuit elements, IC ₁₄ is a T-type flip-flop,
IC ₁₅ is EXOR circuit element, BT is battery, LCD
is a liquid crystal that constitutes a mirror, and R ₁ to R ₂₀ are resistors. The switch modes of the switches SW to _SW3 are as shown in Table 1.

〔Effect of the invention〕

As is clear from the above-described embodiments, according to the present invention, when the surroundings are dark such as at night, the irradiation light from lamps such as street lights and neon lights that are lit using an AC power source and the lamps that are lit using a DC power source can be used. The mirror reflectance is reduced only when it detects the light emitted from the headlights of the following vehicle, so it does not directly dazzle the driver. The reflectance of the mirror does not decrease even with light that does not give any negative effects, and the reflectance of the mirror can be changed under favorable conditions even at night, contributing to safe driving.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram for explaining an embodiment of an anti-glare mirror device according to the present invention, FIG. 2 is a characteristic diagram of the light receiving element of FIG. 1, and FIG. 3 is a lighting waveform diagram of a lamp.
FIG. 4 is a low-pass filter characteristic diagram. 1...Switch circuit, 2...Ambient brightness detector, 3...Light detection section that detects incident light from the rear, 3-1...Filter circuit, 4...AND circuit, 5...Delay circuit , 6...Liquid crystal drive circuit,
7... Constant voltage circuit, 8... Power supply reverse connection protection circuit.

Claims (1)

[Claims] 1 A first light detection unit that receives and detects the light irradiated from the rear of the vehicle, a second light detection unit that receives and detects the surrounding brightness, and a DC power supply provided in the second light detection unit to turn on the light. An anti-glare mirror device comprising: a filter circuit that selects and identifies only the irradiated light that is illuminated by the DC power source; and a drive circuit that reduces mirror reflectance only when the irradiated light that is lit by the DC power source is detected. .