JPH1062336A - Raindrop detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a raindrop detector which has a large raindrop detection area so that the detection precision of raindrop is not reduced. SOLUTION: This device is a vehicle raindrop detector having a light emitting element 2 arranged toward a windshield 1 and a light receiving element 3 arranged toward the windshield 1 and receiving the light emitted from the light emitting element 2 and reflected by the windshield 1, which detects the presence of a raindrop 7 on the front glass on the basis of the change of the light receiving quantity in the light receiving element 3 caused by the raindrop 7 on the windshield 1. The light emitting element 2, the light receiving element 3 and the windshield 1 are set so as to be relatively movable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a raindrop detecting device, and more particularly to a so-called reflective raindrop detecting device for detecting raindrops attached to a windshield, etc., for an automatic wiper system of a vehicle. It is about.

[0002]

2. Description of the Related Art In recent years, as part of automation of on-vehicle equipment,
Detecting weather conditions and automatically activating the wiper,
The number of vehicles equipped with a so-called automatic wiper system that changes the operation speed is increasing. In this auto wiper system, for example, in a car, a windshield, a radiator grill,
A raindrop detector, such as a front bumper, is provided on the front side of the vehicle to detect the presence of raindrops.

Here, as a raindrop detecting device installed on a windshield, there is a so-called reflection type raindrop detecting device utilizing a difference in refractive index between the windshield and the atmosphere. As shown in FIG. 14, the reflection type raindrop detecting device includes a light emitting element 5 inside a windshield 51.
2 and a light receiving element 53 are arranged via prisms 54 and 55, respectively. In this case, the light emitting element 52
When the light is irradiated toward the windshield 51 from above, the light is totally reflected inside the windshield 51 due to the difference in the refractive index between the air and the glass, travels, and is guided to the light receiving element 53 by the prism 55.

On the other hand, as shown in FIG. 15, when water droplets 56 adhere to the windshield 51, the water droplets 56
Is smaller than that of the windshield 51, the light that reaches that portion leaks outward through the water droplet 56 without being totally reflected. Therefore, the amount of light received by the light receiving element 53 is reduced as compared with the case where there is no water droplet 56, and the light receiving element 53
Output changes. Conventionally, the reflection type raindrop detecting device detects the presence of the raindrop 56 by measuring the amount of light received by the light receiving element 53 using this principle.

[0005]

However, in such a reflection-type raindrop detecting device, when the distance between the light-emitting element 52 and the light-receiving element 53 is increased in order to enlarge the raindrop detection area, the light attenuation is reduced. As a result, there is a problem that the accuracy of raindrop detection is reduced.

Further, since the light receiving element 53 is disposed facing outward, there is another problem that the light receiving element 53 is easily affected by external light.
Further, there is a problem that the presence of raindrops cannot be accurately detected due to the influence of irregular reflection due to a scratch on the windshield or the like.

SUMMARY OF THE INVENTION An object of the present invention is to provide a raindrop detection device having a large raindrop detection area and the detection accuracy of raindrops is not reduced.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0009]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

That is, in the raindrop detecting device of the present invention, the light emitting element disposed toward the raindrop detecting target member, and the light emitting element disposed toward the raindrop detecting target member and emitted from the light emitting element and reflected by the raindrop detecting target member. A light-receiving element for receiving light, a raindrop detecting device for a vehicle that detects the presence of raindrops based on a change in the amount of light received by the light-receiving element caused by raindrops on the raindrop detection target member, and It is characterized in that the raindrop detection target member is installed so as to be relatively movable. In this case, the raindrop can be captured as a pulse signal due to the relative movement between the two.

The raindrop detection target member may be a windshield of a vehicle. At this time, the light-emitting element and the light-receiving element are housed in a detection unit movably disposed on the inner surface side of the windshield. The relative movement between the light emitting element and the light receiving element and the raindrop detection target member may be performed.

Further, a housing accommodating the light emitting element and the light receiving element is provided, and the raindrop detection target member is a turntable formed rotatably in the housing to receive raindrops entering from an opening of the housing. Accordingly, the relative movement between the light emitting element and the light receiving element and the raindrop detection target member may be performed.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) FIG. 1A is a sectional view showing a configuration of a raindrop detecting device according to Embodiment 1 of the present invention.
FIG. 1B is a time chart showing the output of the light receiving element when the raindrop detection is performed by the raindrop detector of FIG. 1A. As shown in FIG. 1A, the raindrop detecting device according to the first embodiment uses total reflection on a windshield (raindrop detection target member) 1 in principle, similarly to a conventional reflection-type raindrop detecting device. However, unlike the conventional raindrop detector, the detection unit 4 having the light emitting element 2 and the light receiving element 3 scans the front glass 1 to detect raindrops.

Here, the raindrop detecting device is shown in FIG.
As shown in FIG. 1, a detection unit 4 including a light-emitting element 2 for receiving and emitting infrared light and a light-receiving element 3 is arranged inside a windshield 1.
Is configured to move along the inner surface. That is,
The detection unit 4 is installed so as to be relatively movable with respect to the windshield 1. In this case, the detection unit 4 is installed within the wiping range of the wiper blade, for example, behind the front panel at the lower end of the windshield, and cannot be visually recognized from the outside by attaching a black film that allows infrared light to pass through the inside of the windshield. It is installed in the form.

Also in this detection unit 4, prisms 5 and 6 are provided between the light emitting element 2 and the light receiving element 3 and the windshield 1, similarly to the conventional reflection type raindrop detecting apparatus.
Is provided. Therefore, the light emitted from the light emitting element 2 enters the windshield 1 through the prism 5 and
After total reflection in the windshield 1, the light reaches the light receiving element 3 through the prism 6.

In this case, the distance between the light emitting element 2 and the light receiving element 3 is shown in FIG. 1A so that the light is received by one reflection, but the distance is such that the accuracy of detecting raindrops is not reduced. It suffices if the distance of one reflection is not limited. The prisms 5 and 6 are not always necessary if total reflection is performed in the windshield 1.

Further, a rail is provided on the inner surface side of the windshield 1, and the detection unit 4 is moved by being pressed against the rail by a spring or the like. Thereby, stable operation of the detection unit 4 and close contact with the windshield 1 are achieved, and raindrop detection accuracy is ensured. In the first embodiment, the movement of the detection unit 4 is assumed to be driven by a belt and a motor.
It can be performed by various methods such as rack and pinion. Since the raindrop detection needs to be performed before the wiper wipes the windshield 1, the detection unit 4
Operates before the windshield 1 is wiped while synchronizing with one reciprocating wiping operation of the wiper.

When the raindrop detecting device having such a configuration is operated when the raindrop 7 is attached to the windshield 1 as shown in FIG. 1A, the raindrop detection is performed as follows. Done. That is, when the motion detection unit 4 reaches the inside of the raindrop 7 as indicated by the dashed line, the light emitted from the light emitting element 2 just hits the portion where the raindrop 7 is attached. At this time, part of the light from the light emitting element 2 is related to the relationship between the raindrop 7 and the refractive index of the windshield 1,
It leaks out through the raindrop 7 without total reflection as before. Therefore, the light reaching the light receiving element 3 is smaller than before, and this appears as a change in the output of the light receiving element 3. FIG. 1B shows this state.
The state where the output of the light receiving element 3 changes at the portion of the raindrop 7 is shown. Then, by detecting this change, a raindrop on the windshield 1 is detected.

As described above, according to the raindrop detecting device,
By scanning the detection unit 4 on the front windshield 1, it is possible to widen the raindrop detection range without lowering the raindrop detection accuracy. In addition, the presence of raindrops is captured as a pulse signal, and as described later, it is possible to prevent false recognition due to scratches on the windshield, and to quantitatively measure the “invisible” of the windshield from the amount of raindrops. It becomes possible.

By the way, the windshield 1 is often scratched by various causes such as collision of pebbles, and often adheres dirt which cannot be wiped by a wiper such as paint. In this case, for example, as shown in FIG. 2A, when the windshield 1 has a flaw 8, the light from the light emitting element 2 is irregularly reflected by the flaw 8, and thereby the light receiving element 3
, The output of the light receiving element 3 may change. FIG. 2B shows this state.
It can be seen that a change similar to that of FIG. 1B appears in the output of the light receiving element 3. That is, if the windshield 1 has a flaw, the change in the amount of received light due to the flaw may be erroneously recognized as being caused by the presence of raindrops, and the wiper may malfunction.

Therefore, in the raindrop detecting device, an output change of the light receiving element 3 obtained when no raindrop is present is stored, and this is regarded as an output change due to a flaw, and is canceled from a later detection result to obtain an accurate raindrop. Detection is performed. That is, by moving the detection unit 4 at a constant speed, the position of the flaw on the windshield is specified, and the influence of the flaw is removed by ignoring the output change there.

For example, as shown in FIG. 3A, when raindrops 7 adhere to the windshield 1 having the scratches 8, the output of the light receiving element 3 is originally as shown in FIG. 3B. .
However, of the output changes A and B in FIG. 3B, the change B is caused by the flaw 8, and both are determined to be changes caused by raindrops unless a countermeasure is taken. However, in the raindrop detecting device, the output change B is stored in advance by the previously performed scanning, and the portion of the output change B is canceled by the signal processing. Therefore, the light receiving element 3
3C is recognized as shown in FIG. 3C, and the output change due to the flaw 8 is not recognized. Therefore, the windshield 1
It is possible to accurately detect raindrops without being affected by scratches.

The detection of flaws is performed by scanning the windshield twice without raindrops, and when an output change is detected at the same place, it is regarded as a flaw. In this case, the number of scans for flaw detection is not limited to this, and it is needless to say that the number of scans may be determined once, or may be determined by performing three or more scans.

On the other hand, at the time of specifying the flaw position, a pulse (position detection pulse) having a constant period along with the movement of the detection unit 4.
It is also possible to make the position of the detection unit 4 correspond to the change in the output from the light receiving element 3 based on this. FIG. 4 is a block diagram illustrating an example of a raindrop detection circuit that performs such processing. The circuit shown in FIG. 4 can be applied to the above-described raindrop detection and flaw detection. in this case,
5 by the transmitter 31 at the same time when the detection unit 4 is moved.
A position detection pulse as shown in FIG. The central processing unit 32 instructs the light emitting element 2 to emit light in synchronization with the position detection pulse, and instructs the detection unit driving motor 36 to operate the detection unit 4. On the other hand, the output from the light receiving element 3 is
And the value is stored in the RAM 33 in association with the position detection pulse. That is, the correspondence between the pulse number and the output change of the light receiving element 3 is stored.

Next, further scanning is performed to obtain the output of the light receiving element 3. The central processing unit 32 stores the result in the RAM 3
Compare with the previous result called from # 3. Then, in the case where an output change is obtained in both cases despite the absence of raindrops, it is determined that the pulse position is flawed.

For example, in FIG. 5A, an output change occurs at the position of the pulse 2 and if an output change occurs at the same position even in the second scan, the output change at the time of the pulse 2 will be damaged. It is assumed to be due to. Therefore, after that, FIG.
When the detection result as described above is obtained, the change at the time of the pulse 2 is considered to be caused by the flaw, and the central processing unit 32 determines only the change at the time of the pulses 4 and 6 as shown in FIG. Recognize that it is caused by raindrops. When a raindrop amount equal to or greater than the threshold value stored in the ROM 34 is detected, a command is issued to the wiper motor 35 to operate the wiper. As a result, the position of the flaw can be accurately specified, and the accuracy of raindrop detection can be further improved.

Using this pulse transmission, the ratio of the number of pulses for one scan of the detection unit 4 to the number of pulses during the period during which raindrops are recognized indicates how much raindrops adhere to the windshield surface. Can be calculated. Thus, for example, even when raindrops are swaying or flowing due to wind pressure when the vehicle is traveling, the area covered by the raindrops on the windshield can be obtained. In other words, the raindrop detecting device can quantitatively measure the “invisibility” of the windshield. Note that one scan here means one-way operation of the reciprocating operation of the detection unit 4.

For example, it is assumed that the output of the light receiving element 3 fluctuates due to the influence of the wind pressure, and the output as shown in FIG. 7A is obtained. In this case, when the output change is binarized as shown in FIG. 7B to determine the correspondence with the pulse, it is recognized that the output change occurs at the time of the pulses 5 and 6. That is,
At this time, two pulses (2/2 /
It is recognized as the raindrop amount of 8). These processes are also described in FIG.
Is performed by the central processing unit 32.

Here, the relationship between the amount of raindrop recognition (the ratio of the number of pulses for one scan to the number of pulses in the raindrop recognition period) and "invisibility" is measured in advance and stored in the ROM 34.
In other words, in the example of FIG. 7, it is determined how many pulses out of the eight pulses should be used to operate the wiper to secure the field of view when the recognition of the raindrop is obtained. And
For example, 4 pulses (4/8) out of 8 pulses are set as a threshold value in the ROM 34, and scanning is performed again, and when the amount of recognized raindrops exceeds the value, the central processing unit 32
An output of the wiper operation is issued to the wiper motor 35. In this case, it is possible to further associate the raindrop recognition amount with the wiper speed.
Control such as low speed operation for 6/8 and high speed operation for 8/8 is also possible.

(Embodiment 2) Next, a raindrop detecting apparatus according to Embodiment 2 of the present invention will be described. FIG. 8 is a perspective view showing the structure, and FIG. 9 is a sectional view thereof.

The raindrop detecting device according to the second embodiment is of a type in which the raindrop detecting device according to the first embodiment moves in parallel inside the windshield 1, whereas the detecting unit 4 is disposed inside the windshield 1. It is a type that rotates and moves. The raindrop detection device is installed with the windshield facing the rear of the room mirror, for example, within the wiping range of the wiper blade. The same members as those in the first embodiment are denoted by the same reference numerals, and the details are omitted.

As in the first embodiment, the raindrop detecting device also has a light emitting element 2 and a light receiving element 3 and a detecting unit 4 having prisms 5 and 6. However, in the raindrop detecting device according to the second embodiment, FIGS.
As shown in (1), the detection unit 4 is connected to a motor 9 via a shaft 10, and rotates around the shaft 10 inside the windshield 1. Also in this case, a change in the amount of light received by the light receiving element 3 is converted into an electric signal and captured by the raindrops 7 attached to the windshield 1, and the operation of the wiper and the operation speed are controlled based on the converted signal. The detection of raindrops and flaws is the same as described above. However, one scan in the first embodiment means an operation for one rotation of the detection unit 4 here.

(Embodiment 3) A raindrop detecting apparatus according to Embodiment 3 of the present invention will be described. FIG. 10 is a sectional view showing the configuration.

As shown in FIG. 10, the raindrop detecting device according to the third embodiment uses the light emitting element 2 and the light receiving element 2 to detect the raindrops 7 attached to the turntable (raindrop detection target member) 12 mounted in the housing 11. This is detected by the element 3.
The raindrop detection device is mounted on the front side of the vehicle such as a front grill of the vehicle such that raindrops blow into the opening 13 of the housing 11.

Here, a turntable 12 made of a light-transmitting member such as an acrylic resin is attached to the housing 11 of the raindrop detecting device so as to be rotatable about a rotation shaft 14. A bevel gear 1 is provided at the lower end of the rotating shaft 14.
5 is attached and meshes with a bevel gear 18 provided on a rotating shaft 17 of a motor 16. Therefore, the turntable 12 is rotated at a constant speed in the housing 11 by the motor 16.

A light emitting element 2 and a light receiving element 3 are provided in the housing 11.
The light emitting element 2 and the light receiving element 3 are installed so as to be relatively movable. In this case, turntable 1
When no raindrops exist on the light emitting element 2, the light emitted from the light emitting element 2 enters the turntable 12, where it is totally reflected and received by the light receiving element 3.

On the other hand, an opening 13 is formed in the housing 11, from which raindrops 7 enter the housing 11 and fall on the turntable 12. Then, the raindrops 7 reach the portion irradiated with the light from the light emitting element 2 as the turntable 12 rotates as it is. Then, the first embodiment,
As in 2, the total reflection state is hindered by the raindrops 7, and the amount of light received by the light receiving element 3 decreases. And that is the light receiving element 3
And the presence of raindrops is detected, and the operation and operating speed of the wiper are controlled based on this output change.

The raindrops 7 that have once passed through the place where the light receiving element 2 and the like are installed are dropped from the turntable 12 by the wiping rubber 19, and the raindrops 7
The turntable 12 in the state where there is no is exposed. As a result, the latest rainfall state can always be detected.

FIG. 11 shows a modification of the raindrop detecting device of FIG. 10, in which the light emitting element 2 and the light receiving element 3 are installed on the upper surface of the turntable 12. In this case, raindrop 7
Is detected by detecting a change in the amount of light received by the light receiving element 3 due to light reflected by the raindrops 7. That is, in the case of the configuration of the third embodiment, not only total reflection by the turntable 12 but also development to a reflection type raindrop detection device utilizing the influence of reflection by the raindrop 7 is possible.

(Embodiment 4) In addition, a raindrop detecting apparatus according to Embodiment 4 of the present invention will be described. FIG. 12 is a sectional view showing the configuration, and FIG. 13 is a plan view thereof. Although the fourth embodiment is not a so-called reflection type raindrop detecting device, the configuration of the third embodiment will be described as one of deployment examples that can be used for other types of raindrop detecting devices.

The raindrop detecting device according to the fourth embodiment is a reflection type raindrop detecting device that detects the presence of a raindrop by reflecting light, whereas the raindrop detecting device according to the third embodiment detects a raindrop by intercepting a light beam by the raindrop. Is a kind of so-called passing object recognition type raindrop detecting device.

In the raindrop detecting device, two light-emitting elements 21 and 23 and light-receiving elements 22 and 24 are provided in the housing 11 so as to face each other, and a turntable 12 on which the raindrop 7 is placed is provided between them. It is configured to pass. Note that the other configuration is the same as that of the third embodiment, so that the details are omitted.

Here, the raindrops 7 on the turntable 12 are
From the light emitting elements 21 and 23 to the light receiving elements 22 and 24
The presence of the raindrop 7 is detected by blocking the light beam toward. In other words, the amount of light received by the light receiving elements 22 and 24 is reduced due to the interruption of the light beam by the raindrops 7, and the change in the output signal from the light receiving elements 22 and 24 is detected to detect raindrops.

In the examples of FIGS. 12 and 13, raindrop detection is performed by using two sets of light receiving and emitting elements. However, the detection may be performed by one set of light receiving and emitting elements. A light-emitting element can be used. Furthermore, the light emitting and receiving elements do not necessarily have to be arranged in the same radial direction as shown in FIGS. 12 and 13, but may be arranged so as to be shifted in the circumferential direction.

Although the invention made by the present inventor has been specifically described based on the embodiment, the invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the invention. Needless to say,

For example, in the above-described embodiment, an example has been described in which the light-emitting element and the light-receiving element are those that receive and emit infrared light. Any wave may be used.

In the above description, the case where the invention made by the inventor is mainly applied to a raindrop detecting device for a vehicle, which is a field of use, has been described. However, the present invention is not limited to this. It can also be applied to the provision of weather information at hotels and the like.

[0049]

Advantageous effects obtained by typical ones of the inventions disclosed in the present application will be briefly described.
It is as follows.

(1) Since the light emitting element and the light receiving element are relatively movably mounted on a member for detecting raindrops such as a windshield and a turntable, a large raindrop detection area can be obtained without lowering detection accuracy. Can be.

(2) Since the presence of a raindrop is regarded as a pulse, by simultaneously outputting a position detection pulse,
It is possible to prevent erroneous recognition due to a scratch on the windshield, and to quantitatively measure the “invisibility” of the windshield from the amount of raindrops.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view illustrating a configuration of a raindrop detection device according to a first embodiment of the present invention, and FIG. 1B is a light reception when raindrop detection is performed by the raindrop detection device of FIG. 6 is a time chart showing an output of an element.

2A is a cross-sectional view showing a state in which a damaged windshield is scanned by the raindrop detector of FIG. 1, and FIG. 2B is a time chart showing an output of a light receiving element in that case. .

FIG. 3A is a cross-sectional view illustrating a state in which the raindrop detecting device of FIG. 1 scans a damaged windshield to which raindrops are attached, and FIG. 3B illustrates an output of a light receiving element in that case. FIG. 4C is a time chart showing a state in which an output change due to a flaw is canceled by signal processing.

FIG. 4 is a block diagram illustrating an example of a raindrop detection circuit used in the raindrop detection device of FIG. 1;

5A is a time chart showing an output of a light receiving element of the raindrop detecting device of FIG. 1, and FIG. 5B is a time chart showing a position detection pulse emitted simultaneously with the movement of the detection unit.

6A is a time chart showing an output of a light receiving element when a damaged windshield is scanned by the raindrop detector of FIG. 1, and FIG. 6B is a timing chart showing a position emitted simultaneously with the movement of the detection unit. 4 is a time chart showing a pulse, and FIG. 4C is a time chart showing a state in which an output change due to a flaw is canceled by the circuit of FIG.

7A is a time chart showing an output of a light receiving element when raindrops attached to a windshield are affected by wind pressure by the raindrop detector of FIG. 1, and FIG. 7B is an output value thereof. And (c) is a time chart showing a position detection pulse issued simultaneously with the movement of the detection unit.

FIG. 8 is a perspective view illustrating a configuration of a raindrop detecting device according to a second embodiment of the present invention.

FIG. 9 is a cross-sectional view of the raindrop detecting device of FIG.

FIG. 10 is a cross-sectional view illustrating a configuration of a raindrop detecting device according to a third embodiment of the present invention.

FIG. 11 is a sectional view showing a modified example of the raindrop detecting device of FIG. 10;

FIG. 12 is a cross-sectional view illustrating a configuration of a raindrop detecting device according to a fourth embodiment of the present invention.

FIG. 13 is a plan view of the raindrop detecting device of FIG. 12;

FIG. 14 is a cross-sectional view illustrating a configuration of a conventional raindrop detecting device.

FIG. 15 is a cross-sectional view illustrating how raindrops are detected by a conventional raindrop detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Windshield (raindrop detection target member) 2 Light emitting element 3 Light receiving element 4 Detector unit 5 Prism 6 Prism 7 Raindrop 8 Scratches 9 Motor 10 Axis 11 Housing 12 Turntable (Raindrop detection target member) 13 Opening 14 Rotation axis 15 Shade Gear 16 Motor 17 Rotating shaft 18 Bevel gear 19 Wiping rubber 21 Light emitting element 22 Light receiving element 23 Light emitting element 24 Light receiving element 31 Transmitter 32 Central processing unit 33 RAM 34 ROM 35 Wiper motor 36 Detection unit driving motor 51 Front glass 52 Light emitting element 53 Light receiving element 54 Prism 55 Prism 56 Water droplet

Claims (3)

[Claims] 1. A light-emitting element disposed toward a raindrop detection target member, and a light-receiving element disposed toward the raindrop detection target member and receiving light emitted from the light-emitting element and reflected by the raindrop detection target member. A raindrop detecting device for a vehicle, comprising: an element; and detecting the presence of a raindrop based on a change in the amount of light received by the light receiving element caused by the raindrop on the raindrop detection target member, wherein the light emitting element and the light receiving element A raindrop detecting device, wherein the raindrop detection target member is installed so as to be relatively movable. 2. The raindrop detecting device according to claim 1, wherein:
The raindrop detection target member is a windshield of a vehicle,
The raindrop detecting device, wherein the light-emitting element and the light-receiving element are housed in a detection unit movably arranged on the inner surface side of the windshield. 3. The raindrop detecting device according to claim 1, wherein:
It is a turntable having a housing that houses the light emitting element and the light receiving element, wherein a raindrop detection target member is rotatably formed in the housing and receives raindrops entering from an opening of the housing. Raindrop detector.