JPH10332575A - Detecting apparatus for raindrop - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a detecting apparatus in which the detecting sensitivity of a raindrop is made uniform inside a raindrop detecting area. SOLUTION: A plurality of cylindrical protrusion parts 32 are installed in respective reflecting areas A to C on an optical prism 20. The protrusion parts 32 are formed integrally with the optical prism 20 in this example. In an oval central part as a part corresponding to the light-emitting axis of the light of an LED out of the reflecting areas A to C, the luminance (the optical intensity) of the LED is most intense, and the luminance (the optical intensity) of the LED becomes weak toward the outside from the central position. Then, the scattering of the light of the LED is made much larger in the central part, and the scattering of the light is made small toward the outside, and the distribution density of incident light on a photodiode is made uniform. Concretely, the density (the number of pieces per unit area) of the protrusion parts 32 is made largest in the central part, and the density of the protrusion parts 32 is made small toward the outside from the central part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a raindrop detecting device, and more particularly to an optical raindrop detecting device.

[0002]

2. Description of the Related Art Conventionally, there is an optical raindrop detecting device described in Japanese Patent Application Laid-Open No. 61-116645. In this conventional apparatus, when a raindrop is present on a window glass of a vehicle, the wiper is automatically driven. And
This conventional device utilizes the fact that the reflectance of the glass is different when there is no raindrop on the windowpane, makes it incident on the raindrop detection area of the light windowpane of the light emitting element (light emitting diode), and reflects off the windowpane. The light amount is detected by the light receiving element. Since the detected raindrop detection signal differs depending on whether or not there is a raindrop, the presence or absence of the raindrop adhering to the raindrop detection area is detected by observing a change in the raindrop detection signal.

[0003]

However, in the above-mentioned conventional apparatus, there is a problem that the detection sensitivity of the raindrops is hardly uniform due to the unevenness of the brightness (luminous intensity) of the light emitting element itself. Specifically, the light intensity is highest at the light emission center (light emission axis) of the light emitting element, and the light intensity decreases as the distance from the light emission center increases. Therefore, in the raindrop detection area, when a raindrop adheres to a portion corresponding to the light emission center, the raindrop detection signal greatly changes, but when a raindrop adheres to a portion remote from the portion corresponding to the light emission center, The change of the raindrop detection signal is small. Thus, even if the size of the raindrops is the same, the sensitivity of raindrop detection significantly changes depending on where in the raindrop detection area they adhere.

Therefore, an object of the present invention is to make the raindrop detection sensitivity uniform within the raindrop detection area.

[0005]

Means for Solving the Problems In order to achieve the above object, the present inventor scatters light having a high light intensity among the light of the light emitting element, so that the light is incident from the light emitting element to the light receiving element. I imagined that the distribution of the light intensity of the incident light could be made uniform. With such an idea, according to the first to third aspects of the present invention, by scattering the light of the light emitting element (8), the light intensity of the incident light entering the light receiving element (9) from the light emitting element (8) is reduced. It is characterized by having a uniforming means (25, 32, 34) for making the distribution uniform.

Accordingly, the light of the light emitting element is scattered by the uniforming means, and the distribution of the light intensity of the incident light from the light emitting element to the light receiving element is made uniform. Regardless of where raindrops adhere, the sensitivity of raindrop detection can be made uniform, and the accuracy of raindrop detection can be improved. As specific means, there is provided a transmitting member (10, 30, 31) provided in the optical path between the light emitting element (8) and the light receiving element (9) as in the invention of claim 2, and a uniform means. (32)
Is preferably a concavo-convex portion (32) formed integrally with the transmission member (10, 30, 31).

[0007] Here, the concavo-convex portion is a concavo-convex portion even if the protruding portion is simply formed on the transmissive member, and a concavo-convex portion even if the concavity is simply formed on the transmissive member. In order to achieve the above object, the present inventor has proposed that, as another means, of the light emitted from the light emitting element, the light having a high light intensity is shielded so that the light intensity of the incident light entering the light receiving element from the light emitting element I thought that the distribution could be uniform.

With this idea, the invention according to claim 4 is provided in the optical path between the light emitting element (8) and the light receiving element (9), and has a light intensity of the incident light incident on the light receiving element (9). A light shielding member (25) for making the distribution uniform is provided. Thereby, the distribution density of the incident light incident on the light receiving element is made uniform by the light shielding member, and thus the same effect as the first aspect of the present invention is obtained.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) Hereinafter, an embodiment of the present invention will be described. In this embodiment, the raindrop detecting device of the present invention is applied to an automatic wiper control device of a vehicle. FIG.
1 shows a schematic block diagram of the automatic wiper control device.

As shown in FIG. 1, the automatic wiper control device includes a wiper blade 2 for wiping raindrops attached to a window glass 1 (a raindrop target) of a vehicle, a wiper control device 3 for controlling the operation of the wiper blade 2, and It comprises a raindrop detector 6. The wiper control device 3 includes a wiper motor 4 that is an electric drive unit that drives the wiper blade 2, a wiper motor drive circuit 5, and a wiper switch 7 that is a switch unit that sets start and stop of automatic control of the wiper blade 2. And

The position of the wiper switch 7 can be set in five steps by an occupant. Specifically, the wiper switch 7 includes an OFF for stopping the wiping of raindrops by the wiper blade 2, an automatic for automatically controlling the wiping by the wiper blade 2, an Int for setting the operation (cycle) of the wiper blade 2 to an intermittent operation. Lo, in which the operation (cycle) of the wiper blade 2 is operated at low speed, and Hi, in which the operation (cycle) of the wiper blade 2 is operated at high speed.
There are two installation positions.

That is, in the present embodiment, when the wiper switch 7 is set to auto, the wiper wiping mode is determined based on the raindrop signal detection value detected by the raindrop detector 6, and the wiper control signal corresponding to this is determined. Is output to the wiper motor drive circuit 5 so that the wiper blade 2 is automatically controlled. As shown in FIG. 1, the raindrop detecting device 6 is connected to a heater circuit 21 that controls a heater 20, which is a heating unit that heats the prism 10 described later, when the CPU 14 is powered on. .

In the present embodiment, when the wiper switch 7 is set to the automatic mode, power is supplied from the vehicle power supply 30 to the wiper control device 3 and the raindrop detection device 6. Next, the raindrop detecting device 6
Will be described with reference to FIGS. Note that the structure of the raindrop detecting device 6 is almost the same as that of Japanese Patent Application Laid-Open No. 61-37560, and therefore the description is simplified.

As shown in FIG. 1, a CPU 14 which is an arithmetic processing unit of the raindrop detecting device 6 is turned on, so that a heater 20 which controls a heater 20 which is a heating means for heating an optical prism 10 to be described later is provided. Circuit 21 is connected. Further, when the wiper switch 7 is set to the automatic mode, power is supplied to the raindrop detecting device 6 from the vehicle-mounted power supply 30.

As shown in FIG. 2, the raindrop detector 6 is mounted on the inner surface of the window glass 1. The raindrop detecting device 6 according to the present embodiment includes an LED 8 (a light emitting element, a light emitting diode that emits infrared light, hereinafter, an LED).
(Infrared light) is incident on the window glass 1, the light is reflected by the window glass 1, the reflected light is received by a light receiving element (hereinafter, referred to as a photodiode) 9, and the reflected light is reflected by the photodiode 9. The amount of raindrops attached to the window glass 1 is detected based on the amount of light.

That is, the raindrop detecting device 6 detects that when the raindrops adhere to the window glass 1, the reflectance at the window glass 1 changes (decreases), and the amount of light received by the photodiode 9 decreases. The amount of raindrops is detected using this. The LED 8 is connected to a CPU as shown in FIG.
The light emission timing (the timing of turning on and off the power from the vehicle-mounted power supply 30) is controlled by the LED drive circuit 15 through the LED drive circuit 15. The output value of the photodiode 9 is subjected to light-to-voltage conversion by a detection amplification circuit 16 as shown in FIG.

The raindrop detecting device 6 is installed on the inner surface of the window glass 1 in the interior of the vehicle, as shown in FIG. As shown in FIG.
As shown in the figure, on the inner surface side of the window glass 1, the light from the LED 8 is surely incident on the photodiode 9.
An optical prism 10 that is a transmission member that refracts the light of the LED 8 is provided. The optical prism 10 is made of polycarbonate acrylic or the like, and is attached to the window glass 1 with a transparent adhesive 17.

The prism 10 is provided in the window glass 1.
The reflected light from the vehicle is reflected and received by the photodiode 9, and the solar radiation from outside the vehicle cabin
To block incident light. That is, for example, when no raindrops adhere to the window glass 1, the light from the LED 8 passes through the optical prism 10 and is totally reflected on the inner surface of the window glass 1 as shown in FIG. Thereafter, the totally reflected infrared light is totally reflected by the reflecting portion 19 of the optical prism 10 as shown in FIG. 1, is totally reflected again on the inner surface of the window glass 1, and enters the photodiode 9.

On the other hand, for example, when raindrops adhere to the window glass 1, the light from the LED 8 as shown in FIG.
The amount of light entering the photodiode 9 from the LED 8 is reduced without being totally reflected on the inner surface of the window glass 1 after passing through the optical prism 10. Thereby, the wind glass 1
Since the raindrop detection signal of the photodiode 9 is different between when the raindrop is present and when it is not present, the presence or absence of the raindrop can be detected by observing the change in the raindrop detection signal, and the wiper blade 2 is automatically turned on accordingly. Activate.

In FIG. 2, reference numeral 11 denotes a base for holding the LED 8 and the photodiode 9, and 12 denotes an electric circuit having the LED drive circuit and the detection and amplification circuit 16. Also, such an LED 8, a photodiode 9, a base unit 11, and an electric circuit unit 12
Are housed and integrated in the cover cases 13a and 13b. The raindrop detector 6 integrated in this manner is fixed to the inner surface of the window glass 1 with an adhesive 17 or the like.

Here, the optical prism 10 according to the present embodiment has a plate-shaped reflecting portion 19 whose central portion in FIG. 2 is depressed. A heat transfer plate 22 made of a metal having excellent heat transfer properties is arranged on the back surface (inside of the vehicle compartment) of the reflection portion 19. The heater 20 is disposed at a position corresponding to the reflecting portion 19 on the back surface of the heat transfer plate 22.

Further, since the optical prism 10 is disposed near the window glass 1 as shown in FIG. 2, for example, in winter when the outside air temperature is low, the temperature tends to be low due to running of the vehicle or the like. As shown in FIG. 2, the reflection portion 19 has an intermediate portion in the optical path and has a considerably smaller thickness than other portions. Therefore, particularly, the temperature of the reflection portion 19 tends to be low, and dew condensation tends to occur. The reason why the thickness of the reflecting portion 19 is made smaller than that of the other portions is that the physical size of the raindrop detecting device 6 in the vertical direction in FIG. 2 can be reduced.

For this reason, in the present embodiment, by disposing the heater 20 on the back of the reflector 19,
The dew condensation of the reflection part 19 is prevented beforehand. The heater 20 is made of a heating wire such as a nichrome wire, and is housed in a plate-like cover case 23 made of rubber as shown in FIG. Therefore, the heater 20 is not actually shown in FIG. In addition, in the cover case 23, in addition to the heating wire, a temperature sensor 24 (see FIG. 1) serving as a means for detecting the temperature of the heating wire (the cover case 23, the optical prism 10) is built. The heater control circuit 21 controls the temperature of the optical prism 10 to a predetermined temperature (for example, 40 ° C.) based on the temperature detected by the temperature sensor 24.

The heat transfer plate 22 is arranged with a slight space 35 separated from the back surface of the reflection section 19. this is,
This is because the reflectance of the optical prism 10 is set such that the infrared light from the LED 8 is totally reflected to the air. Further, the heat transfer plate 22 is for efficiently transmitting the heat generated by the heater 20 to the entire optical prism 10. Therefore, the heat transfer plate 22 in the present embodiment is arranged so as to extend not only to the rear surface of the reflection unit 22 but also to both ends of the optical prism 10 in the figure as shown in FIG.

In FIG. 2, reference numeral 25 denotes a visible light cut filter for blocking the incidence of visible light on the photodiode 9, and is formed of, for example, acrylic resin. Here, the solar radiation of course enters the window glass 1. The optical prism 10 prevents this solar radiation from entering the photodiode 9. However, even if the optical prism 10 is used, it is difficult to completely block sunlight from the photodiode 9. Therefore, the visible light cut filter 25 is provided to cancel the influence of the solar radiation on the photodiode 9.

In the drawing, reference numeral 30 denotes a lens which converts the light from the LED 8 into parallel light and then transmits the light through the optical prism 10, and reference numeral 31 denotes a light which has passed through the optical prism 10 and further converted into parallel light. It is a lens that converts the light and makes it incident on the photodiode 9. Next, details of the optical prism 10, which is a main part of the present invention, will be described with reference to FIG. FIG. 3A is a single view of the optical prism 10 and corresponds to FIG. FIG. 3B is a top view of FIG. 3A viewed from above to below.

As shown in FIG. 3B, in this example, three lenses 30 and 31 are provided respectively. Therefore, in this example, the light of the LED 8 is emitted toward three raindrop detection areas in the windshield 1. Then, as shown in FIG.
1, three reflection areas A to C
Exists. These reflection areas A to C are shown by ellipses for easy understanding in the drawing.

Each of the reflection areas A to C has the structure shown in FIG.
(A) As shown in (b), a plurality of columnar projections 32
(A hemisphere having a diameter of 0.5 mm). In the present example, these convex portions 32 are formed integrally with the optical prism 10 and are formed so as to protrude into a space 35 between the electric heating plate 22 and the reflecting portion 19. And the convex part 32
Further, the light from the LED 8 is scattered to make the distribution of the light intensity of the light incident on the photodiode 9 uniform. In the present example, among the reflection areas A to C, as shown in FIG. 3B, the elliptical central portion, which is the portion corresponding to the light emission axis of the light of the LED 8, has the highest luminance (light intensity) of the LED 8. It becomes a strong place, and the brightness (light intensity) of the LED 8 becomes weaker toward the outside from this central part.

Therefore, in this embodiment, the distribution of the light incident on the photodiode 9 is made uniform by increasing the scattering of the light from the LED 8 at the center portion and decreasing the scattering of the light toward the outside. Is becoming Specifically, FIG.
As shown in (b), the density (the number per area) of the convex portions 32 was maximized at the central portion, and the density of the convex portions 32 was reduced toward the outside from the central portion.
This has the following effects.

FIG. 4 shows the test results studied by the present inventors. However, this test condition is based on the condition that there is no raindrop on the windshield 1, and the output change of the photodiode 9 when a raindrop having a raindrop diameter of 1 mm adheres to a different part in the raindrop detection area indicated by 33 in FIG. It is what saw.
As can be seen from this, in the conventional product, for example, if raindrops adhere to different positions in the X-axis direction in the raindrop detection area, the output changes greatly even if the raindrop diameter is the same.
Accordingly, the accuracy of raindrop detection greatly differs depending on where in the raindrop detection area raindrops adhere. As a result, the amount of raindrops adhering to the windshield 1 cannot be accurately detected, and it becomes difficult to automatically control the wiper according to the amount of raindrops.

However, in the present invention, since the brightness of the light of the LED 8 incident on the photodiode 9 is corrected by the convex portion 32 to be uniform, as shown in FIG.
The output change has a flat characteristic in the axial direction. Therefore, no matter where the raindrops are attached in the raindrop detection area, the raindrop detection sensitivity can be made uniform, and the raindrop detection accuracy can be improved. As a result, raindrops adhering to the windshield 1 can be accurately detected, and automatic control of the wiper according to the raindrops can be accurately performed.

(Second Embodiment) In the first embodiment,
By forming the convex portion 32 on the reflecting portion 19, the distribution of the light intensity of the incident light incident on the photodiode 9 is made uniform, but instead of the LED 8 and the photodiode 9 in this example, A light shielding plate was provided in the optical path. In this example, as this light shielding plate, as shown in FIG. 5, a light shielding material 34 (for example,
Epoxy, acrylic resin) is applied. Also,
As shown in FIG. 5, the light-shielding member 34 has a large application area per area at a part corresponding to the light emission axis of the light of the LED 8 among the parts where the light passes through the visible light cut filter 25, as shown in FIG. 5. As shown in FIG.
The further outward from the portion corresponding to the light emission axis of D8 light,
The application area per area is small.

Thus, in this example, the same effect as that of the first embodiment can be obtained only by applying the light shielding material 34 to the visible light cut filter 25 and without providing a separate light shielding member. (Other Embodiments) In the first embodiment, the projections 32 are formed on the optical prism 10.
The convex portions 32 may be formed on 0 and 31.

In each of the above embodiments, the convex portion 32 is formed so that the distribution of the light intensity of the incident light incident on the photodiode 9 becomes uniform. However, the concave portion may be formed in reverse. In the second embodiment, the visible light cut filter 25 is used as a light-shielding plate. However, a separate light-shielding plate may be provided, or a light-shielding plate may be applied to the outer surface of the reflection unit 19 and the lenses 30 and 31. Is also good.

In the above embodiments, the light shielding material 34 is applied to the visible light cut filter 25. However, the light shielding material 34 may be formed by vapor deposition, printing, or the like. Further, in each of the above embodiments, a mesh-like plate member may be used as the light shielding plate. In each of the above embodiments, the present invention is applied to a wiper automatic control device that automatically controls the wiper blade 2 of the vehicle according to the detection result of the raindrop detection device. The present invention may be applied to a ship or an aircraft, and may be applied to any device that detects raindrops.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a wiper automatic control device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a raindrop detection device in the embodiment.

FIG. 3A is a detailed view of an optical prism in the embodiment, and FIG. 3B is a top view of FIG. 3A as viewed from above in the figure.

FIG. 4 is an output characteristic diagram of the raindrop detecting device in the embodiment.

FIG. 5 is a detailed view of a visible light cut filter according to a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... windshield, 8 ... LED, 9 ... photodiode, 10 ... optical prism, 25 ... visible light cut filter, 31 ... lens, 32 ... convex part.

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // G01W 1/14 G01V 9/04 G (72) Inventor Shinji Wakabayashi 1-1-1, Showa-cho, Kariya-shi, Aichi Pref.

Claims (5)

[Claims] 1. A light emitting element (8) that emits light toward a raindrop object (1) to which a raindrop adheres, and receives light reflected by the raindrop object (1) from the light emitting element (8). A light-receiving element (9), wherein the light-receiving element (9) detects raindrops attached to the raindrop object (1) based on the amount of reflected light received by the light-receiving element (9); Uniform means (25, 32, 3) for scattering the light of the element (8) to uniform the distribution of the light intensity of the incident light incident on the light receiving element (9) from the light emitting element (8).
4) A raindrop detecting device, comprising: 2. A transmitting member (10, 30,...) Provided in an optical path between the light emitting element (8) and the light receiving element (9).
31), wherein the uniforming means (32) includes the transmitting member (10, 30,
2. The raindrop detecting device according to claim 1, wherein the unevenness portion is formed integrally with the raindrop portion. 3. An optical prism (10) for blocking light other than the light emitting element (8) from entering the light receiving element (9).
The light from the light emitting element (8) emits light from the optical prism (1).
After passing through 0), the light is reflected by the raindrop object (1),
Thereafter, the light is reflected by the reflecting portion (19) of the optical prism (10), is reflected again by the raindrop object (1), and is incident on the light receiving element (9). 3. The raindrop detection device according to claim 2, wherein the optical prism is the optical prism. 4. A light emitting element (8) that emits light toward a raindrop object (1) to which a raindrop is attached, and receives light reflected by the raindrop object (1) from the light emitting element (8). A light-receiving element (9), wherein the light-receiving element (9) detects raindrops attached to the raindrop object (1) based on the amount of reflected light received by the light-receiving element (9); The light receiving element (9) is provided in an optical path between the element (8) and the light receiving element (9);
A raindrop detecting device, comprising: a light-blocking member (25) for equalizing the distribution of the light intensity of incident light incident on the device. 5. The raindrop detecting device according to claim 3, wherein the light shielding member (25) is formed of a visible light cut filter that blocks incident visible light to the light receiving element (9). apparatus.