JPH1062559A - Raindrop detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine the size of a raindrop efficiently by differentiating the variation of output from a light receiving element during passage of a raindrop and setting a threshold for validating the data of a raindrop having diameter larger than a predetermined value thereby increasing the recognition probability of raindrop. SOLUTION: A raindrop detecting section 10 comprises light emitting elements 1a, 1b emitting infrared rays, and a light receiving element 2. The light emitting element 1a emits the same quantity of light as the light emitting element 1b and it is located remotely from the light emitting element 1a. Blockinq of a light beam B has smaller effect on the light receiving element 2 than blocking of a light beam A and the sensitivity to raindrop is differentiated. The quantity of light to be received by the light receiving element 2 when a raindrop having a specified diameter or larger traverses the light beam is measured previously and set as a threshold value in an ROM 5. A CPU 3 fetches an obtained data from an RAM 4, compares the data with the threshold value and validates a data exceeding the threshold value. Consequently, raindrops 7a, 7b can be differentiated based on the diameter and the recognition rate of large raindrop can increased.

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 technique effective when applied to a so-called passing object recognition type raindrop detecting device used in an automatic wiper system for a vehicle.

[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 automatic wiper system, a raindrop detecting device for detecting raindrops is provided on a radiator grill, a front bumper, and the like on a front surface of, for example, an automobile in order to detect a rainfall condition.

Here, as such a raindrop detecting device,
There is a raindrop detecting device of a type in which a light receiving element and a light emitting element are installed facing each other to detect the number of raindrops passing between them, and it has been widely used as a kind of passing object recognition type raindrop detecting device. In this type of raindrop detector, the change in the amount of received light caused by the interception of the light beam by the raindrop is converted into an electric signal to detect the number of raindrops, and FIG. 6 schematically shows an example of this. Here, the light emitting element 51 and the light receiving element 52 are arranged to face each other, and an airflow (arrow) generated as the vehicle travels flows through a space 53 therebetween.
Then, the number of raindrops is detected by a change in the amount of light received by the light-receiving element 52 caused by the raindrops 54 carried along with the airflow, and the operation of the wiper is controlled based on the detected value.

[0004]

However, in such a raindrop detecting device, a raindrop is measured as the same one drop regardless of the size of the raindrop. When it rains here,
Small raindrops tend to fall evenly, and large raindrops tend to fall sparsely. According to the measurement by the inventor, when a raindrop having a diameter of 1 mm or less falls, 65% of the total amount of rainfall exceeds 1 mm and exceeds 2 mm.
22.5% for those less than 2 mm, 7.5% for more than 2 mm and less than 3 mm, and 2.5% for more than 3 mm and less than 4 mm
% Was more than 4 mm and 5 mm or less was 2.5%.
As described above, there are various sizes of raindrops. However, as the detection sensitivity of raindrops is increased, it becomes more difficult to distinguish between large and small raindrops. On the other hand, the greater the size of the raindrop, the greater the effect of one raindrop on the field of view. Therefore, there is a problem that the actual visibility situation cannot be reflected if raindrops are determined with the same weight.

For this reason, a method has been proposed in which the size of a raindrop is regarded as an analog fluctuation of the output voltage of the light receiving element, and the raindrop is classified based on the relationship between the amount of voltage change and the size of the raindrop. However, such a method has a problem that the processing is complicated and cannot cope with a rapid change.

Further, as disclosed in Japanese Patent Application Laid-Open No. 3-25054, a plurality of sensors are provided, and irregularities in the attenuation of the light beam between the sensors are detected to determine the size of raindrops. Has also been proposed. However, also in this case, there is a problem that equipment and processing are complicated, such as modulating each sensor to a different frequency to determine the optical path of each beam, and comparing the obtained data individually.

An object of the present invention is to provide a raindrop detecting device which can efficiently determine the size of raindrops with a simple configuration.

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 and the light-receiving element are provided so as to be spaced apart from each other, and the output of the light-receiving element caused by the raindrop passing between them intercepting the light beam from the light-emitting element to the light-receiving element A raindrop detection device for a vehicle that detects the presence of a raindrop based on a change, wherein a first light beam connected between a light emitting element and a light receiving element, and the first light ray between the light emitting element and the light receiving element. Separately, the output change of the light receiving element caused when the raindrop passes has a second light ray different from the output change of the first light ray. Also, by enabling only an output change equal to or greater than a predetermined value, only the output change when a raindrop having a predetermined diameter or more blocks the light beam is enabled, and the raindrop diameter at which the output change becomes effective is defined as a first light beam. And a threshold value that is different from the second light beam. As a result, even if the diameter of the raindrop is the same, the change in the output is effective for a certain light beam but is not effective for another light beam depending on the raindrop diameter. Therefore, the raindrop is differentiated by the raindrop diameter.

[0011]

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

(Embodiment 1) FIG. 1 is an explanatory diagram showing an outline of a configuration of a raindrop detecting device according to Embodiment 1 of the present invention. The raindrop detecting device according to the present invention sets a plurality of light beams having different light amounts using the directional sensitivity characteristics of the light receiving element and the directional characteristics of the light emitting element, and based on the difference in the light receiving output when the raindrop traverses each light beam. The size of the raindrop.

As shown in FIG. 1, the raindrop detecting device comprises two light emitting elements 1a and 1b emitting infrared light and one light receiving element 2, and the light emitting element 1a and the light receiving element 2 are connected to each other. The configuration includes a raindrop detector 10 having a light beam A (first light beam) connected between the light emitting device 1b and a light beam B (second light beam) connected between the light emitting element 1b and the light receiving element 2. in this case,
The light-emitting elements 1a and 1b and the light-receiving element 2
The output signal of the light receiving element 2 is input to the central controller 3 and stored in the RAM 4. Then, the operation control of the wiper driving motor 6 is performed based on the detection result and the control pattern and the threshold value stored in the ROM 5, and the operation and the operation speed of the wiper are controlled.

Here, in the raindrop detecting device, as shown in FIG. 1, two light emitting elements 1a, 1b
Are disposed facing each other, and the light emitting element 1 a is disposed right in front of the light receiving element 2. That is, the light receiving element 2 is provided at a position where the light beam A emitted from the light emitting element 1a is most strongly received.

On the other hand, the light emitting element 1b has a light emission amount similar to that of the light emitting element 1a, but is disposed slightly away from the light emitting element 1b. In this case, the directional sensitivity characteristic of the light receiving element 2 and the directional characteristic of the light emitting element 1b become larger toward the front and become smaller as the distance from the front increases. Therefore, the light receiving element 2
The light receiving amount of the light beam B from the light emitting element 1b is smaller than that of the light beam A. That is, the effect on the light receiving element 2 when the light beam B is blocked is smaller than that when the light beam A is blocked, and the light beam A and the light beam B have different sensitivities to raindrops. For example, when the light emitting element 1b is arranged so that the light receiving amount of the light beam B becomes 50% of the light receiving amount of the light beam A, the output fluctuation of the light receiving element 2 when a certain raindrop interrupts the light ray B is the same. Is 50% of the case where is shut off.

As a means for weakening the light beam B than the light beam A, a light emitting element 1b which emits less light than the light emitting element 1a is used, and the light emitting element 1b is arranged directly in the direction of the light receiving element 2. May be. Further, a difference in sensitivity can be realized by a combination of a non-directional light emitting element and a direct light receiving element, or a combination of a direct light emitting element and a non-directional light receiving element. However, in order to obtain a configuration in which a plurality of light receiving and emitting elements as described later are combined, the configuration as shown in FIG. 1 is appropriate.

In the raindrop detecting device having such a configuration, the size of the raindrop is identified as follows.

In FIG. 1, it is assumed that, for example, when the large raindrop 7a crosses the light beam A, the light receiving element 2 changes the output by "10". The value “10” is a temporary value set for comparison with other cases to explain the operation of the present apparatus, and is not a limited value having a specific unit. Next, when the raindrop 7a crosses the light beam B, the output change in the light receiving element 2 becomes "5" because the light amount ratio is set to 50% as described above. These values are stored in the RAM 4.

On the other hand, it is assumed that when the small raindrop 7b crosses the light beam A, "6" is obtained as the output change of the light receiving element 2. In this case, when the raindrop 7b crosses the light beam B, the output change becomes "3". These values are also stored in the RAM 4.

Here, the amount of light received by the light receiving element 2 when a raindrop having a predetermined diameter or more crosses the light beam is measured in advance,
This is set in the ROM 5 as a threshold. Then, the central processing unit 3 calls the obtained data from the RAM 4 and compares it with the threshold value, and makes the data that is equal to or more than that value valid. As a result, data of a raindrop having a diameter equal to or less than a predetermined diameter is ignored, and a difference in output change data in the light receiving element 2 occurs depending on the size of the raindrop. In other words, it is possible to differentiate raindrops by raindrop diameter, and it is possible to increase the recognition probability of large raindrops. In this differentiation, it goes without saying that finer discrimination can be performed in consideration of the magnitude of the absolute value of the output change. Further, such a comparison process is executed by a comparator, a logic circuit, or the like provided in the central processing unit 3.

Looking at such processing in the above example, if the threshold value is set to "4", for example, the output change of both the light beams A and B is effective for the large raindrop 7a, but the small change is small. In the raindrop 7b, the output change in the light beam B is smaller than the threshold value “4” and is ignored, and only the output change in the light beam A is valid. For this reason, there is a difference in the data obtained between the raindrops 7a and 7b, and it is possible to count the number of raindrops while judging the size of the raindrop based on the difference. That is, it is possible to perform weighting on the data for the large raindrop. Therefore, it is possible to appropriately change the operation speed of the wiper driving motor 6 by judging the condition of the field of view from the size of the raindrops and the number of the raindrops, and to control the operation of the wiper according to the condition of the field of view. The control data such as the relationship between the raindrop and the visibility condition and the optimum value of the wiper speed under the condition are stored in the ROM 5, and the central control device 3 performs the above-described processing in accordance therewith.

When such a threshold value is set, raindrops whose output change when crossing the light beam A is equal to or smaller than the threshold value ("4" in the above example) are not counted. However, a large amount of even fine raindrops may affect visibility. Therefore, the data obtained by the raindrops is also stored in the RAM 4 and the number thereof is counted. When the number of the data exceeds a certain number, it is determined that the visibility is deteriorated by the fine raindrops and the wiper is activated. It can also be done.

In this embodiment, two light-emitting elements 1a and 1b have been described as a basic configuration for one light-receiving element 2. However, this is a configuration of two light-receiving elements and one light-emitting element. Can of course achieve the same function. In this case, the threshold value is set so that the output change of both light receiving elements is made effective for a large raindrop, and only the output change of one light receiving element is made effective for a small raindrop.

(Embodiment 2) FIG. 2 is an explanatory diagram showing a configuration of a raindrop detector of a raindrop detector according to Embodiment 2 of the present invention. In the second embodiment, a plurality of light-emitting elements and light-receiving elements are alternately arranged to form a raindrop detecting section 10 in order to enlarge an area in which raindrops can be detected. It has become.

In the raindrop detecting device, as shown in FIG. 2, the light emitting elements 11a to 11f and the light receiving elements 12a to 12f
Are alternately arranged. in this case,
The light receiving element 12a has a strong light C from the light emitting element 11a.
(First light beam) and a weak light beam D (second light beam) from the light emitting element 11c.
Light). In addition, the light receiving element 12c is connected to the strong light E (first light) from the light emitting element 11c and the light emitting element 11c.
Weak rays F (second ray) and G from a and 11e
(Second light beam). Similarly, as shown in FIG. 2, the other light receiving elements 11b receive a strong light beam from the opposing light emitting element and a weak light ray from the adjacent light emitting element. The circuit configuration relating to the raindrop detection process is shown in FIG.
Is the same as

In the raindrop detecting device having such a configuration, as described above, the output change in the light receiving element 12a and the like differs depending on which light beam the raindrop 13 traverses.
For example, in the light receiving element 12c, the output change when the raindrop 13 crosses the light rays F and G is smaller than the change when the raindrop 13 crosses the light ray E. Therefore, the size of the raindrop can be identified by appropriately setting the threshold so that the output change when the small raindrop crosses the light beams F and G is ignored.

As described above, in the raindrop detecting device according to the present invention, the number of the first light beam and the number of the second light beam are not limited to one, and a plurality of sets of the first light beam and the second light beam are combined. You may. Furthermore, it is also possible to set each light beam to a different light amount in the first light beam and the second light beam, for example, by setting the light amounts of the light beam F and the light beam G to be different.

[0028]

Next, an outline and results of an experiment conducted by the inventor for confirming the effect of the raindrop detecting device having the above configuration will be described. FIG. 3 is an explanatory diagram showing the configuration of the raindrop detector 10 of the device used in the experiment.

In this apparatus, as the raindrop detecting unit 10, light emitting elements 21a to 21d and light receiving elements 22a to 22d are alternately arranged in the form shown in FIG. 3, and a bar 23 passes between them instead of raindrops. I let it. As the rod 23, a rod having a diameter of 0.89 mm was used as a substitute for a large raindrop, and a rod having a diameter of 0.12 mm was used as a substitute for a small raindrop. FIGS. 4 and 5 show output changes of the light receiving elements 22d, 22c, and 22b when the rod 23 passes through the apparatus and binarized output data obtained by integrating them.

(Embodiment 1) FIG. 4 shows the apparatus of FIG.
It is a graph which shows the output signal at the time of passing a 89 mm bar. In the figure, (a) is the total output data, (b) is the output of the light receiving element 22d, (c) is the output of the light receiving element 22c,
(D) is the output of the light receiving element 22b.

Here, as shown in FIG. 3, each light beam and the point through which the bar 23 passes are respectively referred to as light beams P,
Let Q, R (first ray), X, Y, Z (second ray) and points p, q, r, x, y, z. The output change at this time is displayed in the figure. According to this, for example, in the light receiving element 22d, a small output change is seen when the rod 23 passes the point x crossing the light ray X, and a large output change is seen when the rod 23 passes the point r crossing the light ray R. A similar change is also seen in the light receiving elements 22c and 22b, and six output changes are seen in the total output data.

(Embodiment 2) FIG. 5 is a graph showing an output signal when a rod having a diameter of 0.12 mm is passed through the apparatus shown in FIG. The configuration in the figure is the same as that in FIG.

Here, in the light receiving element 22d, for example, an output change is seen when passing the point r, and almost a slight change is seen when passing the point x. Further, in the light receiving elements 22c and 22b, only the changes at the points q and p are respectively seen, and only three output changes are seen in the total output data. In the case of FIG. 5, since the diameter of the rod 23 is small, the peak of the output change at the points p, q, and r is smaller than that of FIG.

As can be seen from the comparison between FIGS. 4 and 5, when the diameter of the rod is large, the output of the light receiving element changes even with a weak light beam. Can no longer be seen. Therefore, according to the apparatus as shown in FIG. 3, different total output data can be obtained depending on the diameter of the rod. If the diameter of the rod is replaced with the diameter of the raindrop, a difference occurs in the data obtained between the large raindrop and the small raindrop, and the differentiation can be achieved. Further, in this case, the number of output changes differs depending on the size of the raindrop (six large and three small), so that it is also possible to digitally grasp the difference in raindrop diameter.

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

For example, the positional relationship and the number of light emitting elements and light receiving elements may be any as long as the outputs of the light receiving elements are different. For example, a combination of two light emitting elements and two light receiving elements having different light emission amounts may be determined to be large if both outputs are valid and small if only one output is valid. Further, two light emitting elements having different light emission amounts may be arranged close to each other so as to face one light receiving element, so that a difference in the light reception amount occurs depending on the diameter of the raindrop. However, in this case, the diameter of the raindrop is identified based on the amount of received light.
In addition, two or more light emitting elements are arranged for one light receiving element, or conversely, one light receiving element is arranged for two or more light emitting elements, so that raindrops of two sizes are used. Not only that, the diameter of the raindrop can be further subdivided and identified.

Further, the present invention is not limited to the above example, and the raindrop detection area can be further expanded by using more elements. In addition, the configuration of the elements is not limited to a planar one as shown in FIGS. 1 and 2, and each element can be arranged three-dimensionally. Note that the light beam used for raindrop detection is not limited to infrared light, but may be visible light or ultraviolet light.

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.

[0039]

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

That is, the output change of the light receiving element when the raindrop passes is made different by utilizing the directional characteristic of the light emitting element and the directional sensitivity characteristic of the light receiving element, and a threshold value is provided for validating data of a raindrop having a predetermined diameter or more. Thereby, the recognition probability of a large raindrop can be increased, and the raindrop can be differentiated by the raindrop diameter. Therefore, weighting can be performed on the data with respect to the large raindrop, and the operation control of the wiper according to the condition of the field of view can be performed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of a raindrop detecting device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a configuration of a raindrop detector of a raindrop detector according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a configuration of a raindrop detector of an experimental example used for measuring the effect of the raindrop detector according to the present invention.

FIG. 4 is a graph showing an output signal when a rod having a diameter of 0.89 mm is passed through the apparatus having the configuration shown in FIG. 3;

5 is a graph showing an output signal when a device having the configuration of FIG. 3 is passed through a rod having a diameter of 0.12 mm.

FIG. 6 is an explanatory view schematically showing a configuration of a conventional raindrop detecting device.

[Explanation of symbols]

 Reference Signs List 1a light emitting element 1b light emitting element 2 light receiving element 3 central control device 4 RAM 5 ROM 6 wiper driving motor 7 raindrop 7a raindrop 7b raindrop 10 raindrop detector 11a light emitting element 11b light emitting element 11c light emitting element 11d light emitting element 11e light emitting element 11f light emitting element 12a light receiving element 12b light receiving element 12c light receiving element 12d light receiving element 12e light receiving element 12f light receiving element 21a light emitting element 21b light emitting element 21c light emitting element 21d light emitting element 22a light receiving element 22b light receiving element 22c light receiving element 22d light receiving element 23 rod light emitting element 52 light receiving element 53 space 54 raindrop A ray (first ray) B ray (second ray) C ray (first ray) D ray (second ray) E ray (first ray) F ray (second ray) G ray (first ray) 2 rays) P ray (first ray) Q ray (first ray) ) R rays (first light beam) X rays (second light beam) Y beam (second light beam) Z beam (second light beam) p point q point r point x point y location z point

Claims (1)

[Claims] 1. A light-emitting element and a light-receiving element are provided facing each other at a distance, and a raindrop passing between them intercepts a light beam traveling from the light-emitting element to the light-receiving element. A raindrop detection device for a vehicle that detects the presence of a first light beam coupled between the light emitting element and the light receiving element, and a first light ray between the light emitting element and the light receiving element. The output change of the light receiving element generated when passing through the raindrops is different from the output change of the first light ray, and only the output change of a predetermined value or more is enabled. A raindrop detecting device having a threshold value that makes the raindrop diameter different between the first light beam and the second light beam.