JPH0336180B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for detecting fogging caused by dew condensation on the inner surface of a windshield or rear window of a vehicle and automatically removing the fogging.

[Prior Art] Conventionally, when a vehicle's glass becomes foggy due to condensation due to temperature changes or increased humidity, visibility deteriorates and driving becomes difficult. For example, fogging is removed by operating a hot wire heater attached to the inner surface of the glass, a defroster fan motor, etc., but depending on the state of condensation, this operation becomes more frequent, making it difficult to concentrate on driving and reducing safety. This caused problems when driving, and the operation itself was extremely troublesome.

On the other hand, for example, in JP-A-56-87846,
In order to avoid being affected by ambient light, a fogging detection device has been proposed in which the light emitting part and the light receiving part are installed in a path that causes almost total reflection, and the surface condition of the reflective part is detected based on the amount of reflected light. There is a problem in that the mounting positions of the light receiving section and the light receiving section are extremely limited.

Furthermore, Japanese Utility Model Application Publication No. 49-32685 proposes a configuration in which the light emitting element and the light receiving element are integrated into a module so that the installation location of the detection section can be appropriately selected. However, although the purpose of defogging a vehicle's windshield or rear window is to ensure visibility, this proposal requires the detection module to be attached to the area from which fogging is to be removed, which obstructs visibility. There were problems and it was not desirable from a safety standpoint.

Furthermore, as another example, Japanese Utility Model Application No. 56-148954 discloses a configuration in which a light emitter and a light receiver are disposed inside glass.

[Problems to be Solved by the Invention] By the way, according to the laws of physics, the angle of incidence and the angle of reflection on the inner surface of the glass are equal. When arranging the emitter and receiver as separate bodies, this point must be fully taken into consideration when determining the mounting position.

Regarding this point, since there is no concrete example given as to what kind of arrangement is best, the inventors considered an arrangement as shown in FIG. 4 as an experiment.

In this system, a projector 2 is attached to the upper frame of the windshield 1, and a light receiver 6 is attached to the top of the dash board, so that infrared light is reflected at approximately the center part 15 of the windshield 1.

The device developed in this trial is excellent in that it can accurately detect fog without obstructing the driver's field of vision, but it was not until this configuration was adopted that the following additional problems were discovered: .

One of the problems is that there are cases where maps and accessories are placed on the dart board, but
The problem is that the detection light is blocked by these objects, making it impossible to detect fogging.

Another important problem is that, as mentioned above, the projector 2 and the receiver 6 must be arranged in a relationship with equal angles of incidence and reflection according to the laws of physics, but the windshield 1 has a complicated curve. The shape of the curvature is asymmetrical, especially in the vertical direction, so by just slightly changing the position on the center line of the windshield 1, the emitter 2 and receiver 6 had to be precisely determined by making precise drawings and complicated calculations, which caused the problem of troublesome installation.

[Object of the Invention] The present invention solves these problems and can accurately detect cloudy weather without obstructing the driver's field of vision. It was completed with the aim of providing a new configuration that does not hinder detection and allows easy installation of the device.

[Means for Solving the Problems] For this reason, the present invention includes a projector that emits infrared light so that it is reflected on the inner surface of the glass, and an electric signal that receives the reflected light from the inner surface of the glass and outputs an electric signal according to the amount of received light. A fogging system is equipped with a light receiver that detects dew, and a detection circuit that compares the output signal of the light receiver with a predetermined reference value and outputs a fogging detection signal, and detects dew condensation on the inner surface of a windshield or rear window of a vehicle. In the detection device, the light emitter is disposed on a pillar portion serving as a horizontal frame of the windshield or rear window, and is directed to a predetermined position on the center line of the windshield or rear window, and the light receiver is arranged so that the light receiver The projector is characterized in that it is disposed symmetrically with the floodlight on a pillar section that serves as the other horizontal frame of the installed windshield or rear window.

[Function] First, according to the present invention, the projector and the light receiver are disposed in the pillar section that forms the horizontal frame of the windshield or rear window, so that they do not obstruct visibility.

In addition, since the change in the curvature of the inner surface of a windshield or rear window is symmetrical on the left and right sides of the center line, no matter which position on the center line is selected as the infrared light irradiation position, with the above configuration, The emitter and receiver must be installed with the correct angle of incidence and angle of reflection. Therefore, even if the irradiation position is slightly changed in the vertical direction, it can be easily dealt with.
There is no need for any troublesome drawings or calculations. Also, the irradiation position may differ depending on the type of vehicle, but
Dealing with these various attitudes is also easy.

Furthermore, the structure provided in the pillar portion also provides the following remarkable effects.

If an attempt is made to accurately detect cloudy weather using a light projector and a light receiver that are arranged separately, a problem will arise in terms of the S/N ratio unless the amount of light received by the light receiver is large to some extent. Therefore, the amount of light reflected on the cloudy detection surface must be increased to some extent. However, there are restrictions on the amount of light emitted from the projector. To compensate for this, it is necessary to increase the reflectance.

For example, according to "Photophysics" published by Kyoritsu Shuppan Co., Ltd., the reflectance is given as Fresnel's formula as follows.

Reflectance R={sin(θ ₂ −θ ₁ )/sin(θ ₂ +θ ₁ )
} ² This is the formula for S-polarized light, and for P-polarized light it is as follows.

Reflectance R={tan(θ ₁ −θ ₂ )/tan(θ ₁ +θ ₂ )
} ² Note that θ ₁ is the incident angle and θ ₂ is the reflection angle.

In this way, the reflectance R increases as the incident angle θ ₁ increases.

For this reason, an angle of incidence of about 60° to 85° is suitable, and if the emitter and receiver are placed on the pillar next to the inner surface of the windshield, the angle of incidence of the detected light will be approximately 60° to 80°, and the reflected light will be The rate can be increased. On the other hand, since the emitter and receiver are sufficiently far apart, even with such a high reflectance, there is almost no direct light influence. As a result, it is possible to increase the reflectance and perform accurate cloudy detection.

This effect is difficult to achieve with a module in which the light emitting element and the light receiving element are integrated. In other words, in an integrated module, the distance between the light-emitting element and the light-receiving element is shortened, so when the angle of incidence on the detection surface is increased, part of the light from the light-emitting element is not reflected by the glass surface. This is because the light enters the light receiving element directly and the accuracy of cloudy detection deteriorates. In order to prevent this, it is conceivable to provide a light-shielding plate between the light-emitting element and the light-receiving element that are integrated into the module, but since the number of components increases and the device becomes larger, it is difficult to block the field of view. The problem that hinders this becomes even bigger.

Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings. 1 to 3 show an embodiment of the present invention, in which a floodlight 2 that emits infrared light is attached to a pillar section that forms the horizontal frame of a windshield 1 of a vehicle, and a projector 2 that emits infrared light is attached to a pillar section that forms a horizontal frame of a windshield 1 of a vehicle. A light receiver 6 is attached to a pillar portion serving as a horizontal frame of a windshield 1 at a position where infrared light 4 is irradiated onto the windshield 3 and can be reflected, and the reflected light 5 can be received.

As shown in FIG. 3, the floodlight 2 is composed of, for example, an infrared light emitting diode and a convex lens, and is connected to a drive circuit 7, which causes the drive circuit 7 to blink intermittently at a constant period, and to emit red light from the outside. A specific amplitude modulation is applied to distinguish it from external light, and the light receiver 6 is composed of, for example, a photodiode and a convex lens, and the output signal of the photodiode is sent to a comparison control circuit 10 via an amplifier 8 and a detection circuit 9. The comparison control circuit 10 drives the motor 11 of the defogging device. Here, the amplifier 8, the detection circuit 9, and the comparison control circuit 10 are components of the detection circuit 13.

Therefore, when there is no condensation on the inner surface of the glass, the irradiated light 4 from the projector 2 is directed to the central part 3 of the windshield 1.
The reflected light 5 is received by a light receiver 6, and the output signal of the light receiver 6 is amplified by an amplifier 8.
The detection circuit 9 detects the amplitude, inputs it as a voltage corresponding to the intensity of the reflected light to the comparison control circuit 10, and compares it with a preset reference value.

When dew condenses on the inner surface of the glass, the reflected light 5 is scattered, so the intensity of the light incident on the light receiver 6 decreases depending on the state of condensation, and when it decreases below the reference value of the comparison control circuit 10, a fogging detection signal is output. The motor 11 of the defogging device is driven to blow out air from the air outlet 12 of the dash board shown in FIG. 2, and blow it onto the windshield 1 to remove dew condensation. When the condensation is removed, the reflected light 5 becomes stronger again, so the voltage value input to the comparison control circuit 10 becomes higher, and the voltage value input to the comparison control circuit 10 increases.
Stop 1.

In the above embodiment, the motor 1 of the defogging device
1, a hot wire heater or an air conditioner may be operated in response to the fogging detection signal, and furthermore, it is also possible to notify the fogging of the windshield by voice or the like. In addition, by installing the emitter and receiver on the horizontal frame on the inside of the glass, the infrared light will not be blocked even if maps or small items are placed on the dart board or rear window tray, making it difficult to detect fogging on the glass surface. The advantage is that there are no problems.

As described above, there is a projector that emits infrared light so that it is reflected off the inner surface of the glass of a vehicle, a receiver that receives the light reflected by the inner surface of the glass and outputs an electrical signal according to the amount of received light, and a receiver that This fog detection device is equipped with a detection circuit that compares the output signal with a predetermined reference value and outputs a fog detection signal, and is designed to detect dew condensation on the inner surface of the glass. Since the fog removal device can be operated automatically, the driver of the vehicle is freed from the hassle of having to operate it manually each time, and when fog occurs, it is immediately removed to ensure visibility, which greatly contributes to safe driving. There is.

In addition, since infrared light is amplitude-modulated and used, it does not affect the driver in any way, and is not affected by infrared light incident from the outside, making it possible to stably detect cloudy weather. .

Although the above embodiment detects dew condensation on the inner surface of the windshield, dew condensation on the inner surface of the rear glass of the vehicle may also be detected.

[Effects of the Invention] As explained above, according to the present invention, by taking advantage of the geometric characteristics of the windshield and rear window,
It is possible to mount a projector and a light receiver in the correct relationship between the angle of incidence and the angle of reflection without performing troublesome drawings or calculations. Further, although the irradiation position may vary depending on the type of vehicle, it is easy to deal with such various situations.

Furthermore, the configuration provided in the pillar portion of the horizontal frame is suitable for increasing reflectance, and fogging can be detected with high accuracy even if a projector with a small amount of light emission is used.

In addition, unlike the case where the light emitting element and the light receiving element are integrated into a module, the driver's view is not obstructed.

[Brief explanation of drawings]

1 to 3 show a first embodiment of the present invention, FIG. 1 is a front view, FIG. 2 is a plan view, FIG. 3 is a block diagram, and FIG. 4 is a comparative example. It is a front view. 1... Windshield, 2... Floodlight, 4...
Irradiation light, 5... Reflected light, 6... Light receiver, 7... Drive circuit, 8... Amplifier, 9... Detection circuit, 11...
...Comparison control circuit, 13...Detection circuit.

Claims (1)

[Scope of Claims] 1. A projector that emits infrared light so that it is reflected on the inner surface of the glass, a light receiver that receives the light reflected by the inner surface of the glass and outputs an electrical signal according to the amount of received light, and a light receiver that outputs an electric signal according to the amount of received light. A fogging detection device is provided with a detection circuit that compares an output signal with a predetermined reference value and outputs a fogging detection signal, and detects dew condensation on the inner surface of a windshield or rear window of a vehicle, wherein the floodlight is connected to the front The light receiver is placed on a pillar that forms the horizontal frame of the windshield or rear window, and is directed to a predetermined position on the center line of the windshield or rear window, and the light receiver is placed on a pillar of the windshield or rear window on which the projector is installed. A fogging detection device characterized in that it is arranged symmetrically with the floodlight on a pillar portion serving as the other horizontal frame.