JPH0285044A - Water drop sensing device for front wind shield of vehicle - Google Patents

Abstract

PURPOSE:To prevent missensing certainly by equipping a stay base of a room mirror in its inside with a water drop sensor of light reflecting type, which senses eventual existence of water drops on the outer surface of a wind shield. CONSTITUTION:A room mirror 2 furnished in the upper part of a wind shield inside is secured to the bottom of a mirror stay 3, and a stay base 4 at the top of this mirror stay 3 is adhered in the position within the wiper working range (surrounded by two-dotted chain line) in the upper part of the wind shield inside 1. Therein a water drop sensor 5 is installed inside of the stay base 4. This sensor 5 shall be of light reflecting type, and the variation (increment) of the light incident rate to its light receiving element is sensed by a control circuit via a bandpass filter and an envelope sensor circuit, and thereby eventual existence of water drops can be sensed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is directed to a windshield system that detects water droplets adhering to the windshield of a vehicle in order to automatically turn on and off wipers as necessary. The present invention relates to a water droplet detection device.

(Prior Art) Conventionally, a light-reflecting type light-reflecting device is provided which is provided spaced apart from each other inside the front windshield of a vehicle to detect the presence or absence of water droplets on the inner and outer surfaces of the windshield. A water droplet detection device for a front windshield equipped with a water droplet detection sensor is known (for example, JP-A-60
-252044, Japanese Utility Model Application No. 61-36471, and Japanese Utility Model Application Publication No. 62-90244).

(Problems to be Solved by the Invention) In such a conventional device, a water droplet detection sensor is provided at the upper end of the center portion of the front windshield. Therefore, normally the light emitting element → front windshield →
Detection is performed along the path of water droplets → front windshield → light-receiving element, but due to cigarette smoke, the path of light-emitting element → reflective object → light-receiving element is changed. →If each light-receiving element has its own path, it will falsely detect that there are water droplets, even though there are actually no water droplets. In other words, when there is cigarette smoke, infrared light is reflected by the molecules of the smoke and enters the light-receiving element.Furthermore, when the windshield fogs up, diffused reflection occurs on the inside of the windshield. The infrared light is generated and enters the light receiving element. There is a problem in that when the amount of light (overflow) is outside the detection range of the water droplet detection sensor due to fogging of the front windshield, subsequent detection becomes impossible.

The present invention was made in view of the above circumstances, and the light emitting element →
To provide a water droplet detection device for a front windshield that does not create a path other than the path of front windshield -> water drop -> front windshield -> light-receiving element, and that reliably prevents erroneous detection.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a mirror stay base of a rearview mirror that is bonded to the upper inner surface of the front windshield of a vehicle within the wiper wiping range.
The present invention is characterized in that a light reflection type water droplet detection sensor is arranged to detect the presence or absence of water droplets on the outer surface of the front windshield (function). Since the front windshield at the position is not fogged, this detection does not occur. In addition, the water droplet detection sensor does not obstruct the view, and the appearance is good because the water droplet detection sensor is inconspicuous.

(Example) Hereinafter, one example of the present invention will be described based on the drawings. 1st
The figure is a front view of the front windshield of a vehicle equipped with the water droplet detection device of the present invention. In the figure, 1 is the front windshield, and a rearview mirror 2 is provided at the upper inner side of the windshield as shown in FIG. There is. The room mirror 2 is attached to the lower end of the mirror stay 3, and the mirror stay base 4 at the upper end of the mirror stay 3 is connected to the wiper wiping area (encircled by the dotted line in Fig. 1) on the inside upper part of the front windshield 1. The room mirror 2 is attached to the front windshield l via the mirror stay 3 by adhering the mirror stay 3 to the front window glass l. A water droplet detection sensor 5 is arranged inside the mirror stay base 4. The water droplet detection sensor 5 is a light reflection type sensor, and is composed of a light emitting element 5a and a light receiving element 5b as shown in FIG.

As shown in FIG. 5, the light emitting element 5a is electrically connected to an oscillation circuit 6, and the oscillation circuit 6 switches on the light emitting element 5a at a high frequency (5 KHz) to emit high frequency light (infrared light). ), which causes
It can be distinguished from natural light. Light receiving element 5
b is the one that receives the light emitted from the light emitting element 5a;
It is a photodiode or phototransistor that corresponds to the same wavelength as the wavelength of the light emitting element 5a, and performs photoelectric conversion to electrically process the signal. This light receiving element 5b has
A bandpass filter 7, an envelope detection circuit 8, and a control circuit 9 are electrically connected in series in this order. The presence or absence of water droplets can be detected by detecting a change (increase) in the rate at which light enters the light receiving element 5b by the control circuit 9 via the bandpass filter 7° envelope detection circuit 8. . That is, if water droplets adhere to the front windshield 1, the water droplets cause the light emitting element 5a to
Since the emitted light is diffusely reflected, the amount of light entering the light receiving element 5b increases. The light emitted from the light emitting element 5a as shown by the solid line in FIG. 3 is reflected by the front windshield 1 and returns as shown by the broken line.
Since the surface of the window glass l is not a completely smooth surface,
Alternatively, since the light reflected from the light emitting element 5a has directionality but is emitted in all directions, some light directly enters the light receiving element 5b. Therefore, in order to reduce the amount of light that directly enters the light receiving element 5b, as shown in FIG. intersection angle α
is set at a predetermined angle (for example, about 45 degrees), and the intersection angle β between the axis of the light emitting element 5a and the axis perpendicular to the surface of the front windshield l is set at a predetermined angle (as shown in FIG. 4 in side view). For example, each angle is set to approximately 20 degrees. As a result, the light emitted from the light emitting element 5a as shown by the solid line in FIG. The amount of light passing through the path 5a→front window glass l→light receiving element 5b decreases. Note that a wiper driving means (not shown) is electrically connected to the control circuit 9. And the front windshield 1
When water droplets are detected on the outer surface of the line, the wiper is activated.

Next, the operation of the water droplet detection device having the above configuration will be explained.

When water droplets adhere to the outer surface of the front windshield l, light emitted from the light emitting element 5a is diffusely reflected by the water droplets and enters the light receiving element 5b.

The amount of light entering the light receiving element 5b increases compared to the case where there are no water droplets. Therefore, when a change in the amount of light entering the light receiving element 5b, that is, an increase in the amount of light is detected, the wiper is operated by a control signal output from the control circuit 9. Then, when a decrease in the amount of light entering the light receiving element 5b is detected due to the disappearance of water droplets on the front windshield 1, the operation of the wiper is stopped by a control signal output from the control circuit 9.

(Effects of the Invention) As described above, the present invention provides water droplets on the outer surface of the front windshield inside the mirror stay base of a room mirror that is bonded to the upper inner surface of the front windshield of a vehicle within the wiper wiping range. This feature is characterized by the arrangement of a light reflection type water droplet detection sensor that detects the presence or absence of water droplets.

Therefore, even though the water drop detection sensor is located at the top of the front windshield, there is no possibility of cigarette smoke getting into the water drop detection sensor or fogging of the part of the front windshield where the water drop detection sensor is placed. No detection occurs.

In addition, since the water drop detection sensor is integrated inside the mirror stay base, the water drop detection sensor is not noticeable and has a good appearance.Also, since the water drop detection sensor is installed at the top, it can be installed at the bottom. There is no problem with the 4° problem, that is, when driving at high speed, light water droplets such as light rain, light snow, and water droplets cannot be detected because they do not hit the front windshield and obstruct visibility. Furthermore, since the mirror stay base also serves as a mounting member for the water droplet detection sensor, there is no need to provide a dedicated mounting member for the water droplet detection sensor, and the configuration is simple. Furthermore,
Since the water droplet detection sensor is located within the wiper wiping range, changes in the amount of light can be reliably detected.

[BRIEF DESCRIPTION OF THE DRAWINGS] The drawings show one embodiment of the present invention, and FIG. 1 is a front view of the front windshield of a vehicle equipped with the device of the present invention, and FIG. 2 is a view along the line ■-■ in FIG. A cross-sectional view along the line, Figure 3 is I of Figure 2.
4 is a sectional view taken along the line -III of FIG. 3 [V-IV
5 is a block circuit diagram of a water droplet detection sensor used in the apparatus of the present invention. vinegar.

Claims (1)

[Claims] 1. A light-reflecting water droplet is installed inside the mirror stay base of the room mirror, which is attached to the upper inner surface of the vehicle's front windshield within the wiper wiping range, to detect the presence or absence of water droplets on the outer surface of the front windshield. A water droplet detection device for a vehicle windshield, characterized in that a detection sensor is arranged.