JP2001330559A - Foreign matter detecting device and automatic wiper control device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foreign matter detecting device which can detect foreign matter 8 and an automatic wiper control device 1 using it, and automatically jet washing liquid by controlling the automatic wiper when the foreign materials (soil particles in muddy water) adhere. SOLUTION: When an incident light 9 from a light emitting means 2 comes incident on a back surface 11b of a surface 11a on which the foreign matter adhere at an angle the incident light 9 is subjected to total internal reflection, an evanescent wave electromagnetic field is generated. Light quantity of a reflection light 10, which reflects from the back surface 11b of the surface 11a, decreases, as the evanescent wave electromagnetic field is disturbed according to adhering degree of the foreign matter 8 which adhere on the surface 11a. In this foreign matter detecting device, the foreign matter 8 is detected by receiving decreased light quantity of the reflection light 10 by a light receiving means 3. When the foreign matter detecting device is applied to the automatic wiper control device for a vehicle or the like, excellent visibility is automatically available at all times by detecting dirt of the foreign matter on a surface of a window and by automatically wiping in cooperation with a washer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foreign matter detecting device for detecting that foreign matter has adhered to a foreign matter attaching surface using an evanescent wave electromagnetic field, and an automatic wiper control device using the same.

[0002]

2. Description of the Related Art Conventionally, an optical system (Japanese Unexamined Patent Publication No.
No. 0-93333), or a detection device functioning as a moisture detector of a capacitance type (Japanese Patent Application Laid-Open No. 62-178449) is used.

In the case of an optical raindrop detection device, a raindrop detection sensor is mounted on the interior side of the window glass, and the difference in the amount of reflected light depending on the presence or absence of raindrops on the surface of the window glass The amount of raindrop is detected by utilizing the fact that when there is raindrop on the reflection surface, light is transmitted and scattered due to the difference in the refractive index, so that the amount of reflected light decreases.

[0004]

However, a conventional raindrop detector functioning as a moisture detector can detect even water or muddy water (mud as foreign matter is mixed in water). When the concentration of the water is high, or when the water is frequently attached even when the concentration of the muddy water is low, mud gradually remains on the surface of the window glass and becomes dirty on the surface of the window glass, thereby obstructing the view.

[0005] As described above, once the glass is contaminated with mud, it is impossible to wipe the mud with only the wiper, and it is necessary to wipe the wiper while spraying a cleaning liquid. However, conventional raindrop detectors cannot distinguish between rain or water and mud,
It was difficult to automatically perform the wiper operation in conjunction with the washer when muddy water was applied or the glass became dirty with mud.

In view of the above, the present invention and the like have studied a method for making it possible to distinguish between rain or water and mud. If the angle of incidence of the light from the means is reflected so that it is totally reflected even when water adheres to the surface of the object to be detected, the evanescent wave electromagnetic field generated at the boundary surface of the surface of the object to be detected will be a foreign substance. Disturbed by foreign matter adhering to the adhering surface. Then, they discovered that foreign matter can be detected by capturing that the amount of reflected light reflected on the back surface of the surface of the detection target decreases due to the disturbance of the evanescent wave electromagnetic field.

[0007] An object of the present invention is to make it possible to detect the adhesion of foreign matter based on the above idea, separately from rain or water, and to control the wiper wiping while spraying a cleaning liquid automatically when muddy water is applied. An object of the present invention is to provide a detection device and an automatic wiper control device using the same.

[0008]

According to a first aspect of the present invention, there is provided a foreign matter detecting apparatus for detecting the incident angle of light from a light emitting means to an object to be detected. An angle is set so that even when water adheres to the surface, the angle is set so that the light is totally reflected, and the light receiving means receives the reflected light to detect the adhesion of the foreign matter to the detection target. If foreign matter different from rain and water adheres to the surface of the detection target, the foreign matter disturbs the evanescent wave electromagnetic field generated on the surface reflecting the light from the light emitting means, and the amount of reflected light decreases. Is detected by the light receiving means, a foreign substance detecting device capable of detecting foreign substances attached to the surface of the detection target object separately from rain or water can be detected.

According to the foreign matter detecting device of the present invention, the incident angle from the light emitting element has an angle greater than the critical angle so that the particulate matter adhering to the foreign matter adhering surface is totally reflected. In this case, only the particulate matter adhered to the foreign matter-adhering surface disturbs the evanescent wave electromagnetic field, so that the foreign matter detection device can detect the particulate matter as the foreign matter.

According to the foreign matter detecting device of the third aspect of the present invention, when the foreign matter is a mixture with water, the incident angle of the incident light from the light emitting element is set to the water on the surface of the detection target. If the angle of total reflection is not less than 62 degrees and less than 90 degrees, only foreign substances in the water that have not responded to water and adhere to the foreign substance adhered surface will disturb the evanescent wave electromagnetic field, and the particle A foreign substance detection device capable of detecting a substance can be provided.

According to the foreign matter detecting device of the present invention, the foreign matter detecting device according to the first aspect is provided on the indoor side of the window glass to be detected, and the foreign matter detecting device detects foreign matter on the surface of the window glass. The automatic wiper control device performs a wiper wiping operation in conjunction with a washer when dirt due to adhesion is detected.

With this, the foreign object detecting device detects the foreign object attached to the surface of the object to be detected from rain or water and detects the foreign object, and automatically performs the wiper wiping in conjunction with the washer.

According to the foreign matter detecting device of the present invention, the control means for controlling the washer and wiper wiping operation based on the output from the light receiving means according to the degree of the foreign matter adhering to the surface of the window glass is provided. Provided. This control means controls the washer and wiper wiping operations optimally in accordance with the degree of contamination due to the attachment of foreign matter to the surface of the window glass.

Thus, it is possible to provide an automatic wiper control device capable of automatically ensuring a good view of the surface of the window glass.

[0015]

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

The foreign object detecting device and the automatic wiper control device using the same according to the present invention detect that a foreign object has adhered to the foreign object adhering surface using an evanescent wave electromagnetic field.
It can distinguish rain or water from foreign matter (in the case of muddy water, soil particles in water), and can detect only foreign matter without responding to water. If the present invention is applied to, for example, a wiper system for a vehicle, a ship, an aircraft, or the like, it becomes possible to automatically secure a good view of the surface of a window glass, which is a surface on which foreign matter adheres, by a foreign matter detection device.

In the following embodiment, an example in which the present invention is applied to an automatic wiper control device of an automobile and a good view of the surface of a window glass is automatically secured by a foreign object detection device will be described.
This will be described below.

FIG. 1 shows an automatic wiper control device 1 for an automobile.
FIG. As shown in FIG. 1, the automatic wiper control device 1 includes a foreign object detection device, a wiper drive device, and a washer drive device.

The foreign substance detecting device includes an LED (light emitting element) 2, a photodiode (light receiving element) 3, and an LED driving circuit as a foreign substance detecting section for optically detecting the state (presence and amount of raindrops) of the foreign substance on the window glass 11. 31, a detection / amplification circuit 32, a CPU 30, and the like. Here, the control unit 30c inside the CPU 30 controls the detection of foreign matter.

The CPU 30 includes a washer control unit 30a for controlling the supply of the cleaning liquid toward the surface of the window glass 11, a wiper control unit 30b for controlling a wiper wiping operation for wiping the surface of the window glass 11, and a foreign matter detecting device. When the control unit 30 detects dirt due to foreign matter adhering to the surface of the window glass 11, the control unit 30 instructs the washer control unit 30a and the wiper control unit 30b to operate and performs wiper wiping in conjunction with the washer.
c.

When a foreign object is detected, the control unit 30c supplies a predetermined current to the LED drive circuit 31 to cause the LED 2 to emit light.
A detection / amplification circuit 3 detects a detection signal from the photodiode 3
In step 2, the signal is detected, amplified, and input to the control unit 30c.

The wiper driving device comprises a wiper driving circuit 25,
The wiper motor 22 is configured to drive the wiper 20 that wipes off foreign matter attached to the window glass 11 in response to an operation command from the wiper control unit 30b.

The washer driving device comprises a washer driving circuit 26 and a washer motor 23. The washer driving device is directed toward the window glass 11 in order to wipe off foreign substances adhering to the window glass 11 in response to an operation command from the washer control unit 30a. The washing liquid is injected from the washer nozzle 21.

The automatic wiper control device 1 having the above-described configuration.
Transmits a signal indicating that a foreign object is detected by the foreign object detection device to the control unit 30c.
The washer control unit 30a and the wiper control unit 30b
Send to Then, the washer control unit 30a and the wiper control unit 30b operate the wiper drive circuit 25 in accordance with the transmitted signal (the presence or absence of foreign matter and the degree thereof).
And instruct the washer drive circuit 26 to wipe the wiper,
Then, the cleaning liquid is sprayed.

Next, the details of the foreign matter detecting device of the present invention are shown in FIG.
This will be described with reference to FIG. FIG. 2 is a cross-sectional view of the foreign matter detection device. The foreign object detection device includes a prism 4 and an LED in a case 6.
(Light emitting element) 2, photodiode (light receiving element) 3, LED drive circuit 31 shown in FIG. 1, detection / amplification circuit 3
2, a circuit (printed circuit board) 5 or the like in which the CPU 30 and the like are integrated, and is attached using a transparent adhesive 7 that transmits light upward, for example, a portion that does not obstruct the driver's view of the window glass 11 on the vehicle cabin side. .

At the time of operation of the foreign matter detection device, the LED 2 emits incident light 9 composed of infrared light, passes through the prism 4 and the layer of the transparent adhesive 7, is totally reflected by the reflection surface 11b of the window glass 11, and then again. Window glass 1
1. The photodiode 3 receives the reflected light 10 transmitted through the layer of the transparent adhesive 7 and the prism 4 and reflected. The photodiode 3 sends a signal corresponding to the amount of the received reflected light 10 to the circuit board 5, and the signal is processed by the circuit board 5 to obtain a foreign object detection signal. Although not shown, power is supplied from a battery through an ignition key, and is distributed to the circuit board 5. Reference numeral 8 denotes muddy water that has adhered to the surface 11a of the window glass 11.

Next, the principle of detecting a foreign substance by the configuration of the above-described foreign substance detection device will be described. The configuration of the foreign matter detection device is very similar to the optical raindrop detection device described in JP-A-10-332575 and the like, and the incident light 9 from the LED 2 is reflected by the reflection surface 11b which is the back surface of the window glass 11, and The same applies to the case where the reflected light 10 is received by the photodiode 3 and the change in the amount of reflected light received by the photodiode 3 is detected. However, the raindrop detection principle of the raindrop detection device and the foreign matter detection principle of the foreign matter detection device of the present invention are completely different. This is because the incident angles of light from the LED 2 to the reflection surface 11b of the window glass 11 are completely different. Here, the incident angle of light is defined as 0 degree in the case of incidence in a direction perpendicular to the reflection surface 11b of the incident light (directly above in FIG. 2).

The difference between the incident angle of the incident light of the raindrop detecting device and the incident angle of the incident light 9 of the foreign matter detecting device of the present invention will be described. The incident angle of the incident light in the case of the raindrop detecting device must be 41 degrees or more and less than 62 degrees. This is because raindrops are detected by utilizing the difference in the refractive index of the medium that is in contact with the front surface 11a of the window glass 11 that is integral with the reflection surface 11b of the incident light. That is, when there is no rain on the surface 11a of the window glass 11, which becomes the reflection surface 11b of the incident light, that is, an incident angle of 41 degrees or more is required to totally reflect the incident light with respect to the air, and the rain, ie, the water is reflected When coming into contact with the surface 11a of the window glass 11, which becomes the surface 11b, the incident angle must be less than 62 degrees so that the incident light is transmitted without being reflected. In the raindrop detecting device, when there is rain on the surface 11a of the window glass 11 serving as the reflection surface 11b, incident light is transmitted at that portion and the amount of reflected light is reduced by that amount to detect raindrops. Is going.

On the other hand, in the foreign matter detecting device of the present invention,
The incident angle of the incident light 9 from 2 must be in the range of 62 degrees or more and less than 90 degrees (65 degrees in the example of FIG. 2). The reason for making the angle less than 90 degrees is that the incident light 9 is
This is a limit angle at which the reflected light 10 can be received by the photodiode 3. When the incident angle of the incident light 9 is increased, the amount of the reflected light 10 tends to decrease.

The incident angle of the incident light 9 from the LED 2 is 62
The reason is to eliminate the influence of water. By the way, if the incident angle is smaller than 62 degrees, it responds to water and functions as a so-called rain sensor itself. When the incident angle of the incident light 9 is set to 62 degrees or more, the foreign matter (in the case of muddy water, the water is not affected by water such as rain) when the scattering principle of the evanescent wave electromagnetic field generated on the reflecting surface 11b is detected. Soil particles) can be detected, and the concentration of mud can be detected in accordance with the amount of foreign matter.

Further, referring to FIG. 3, the foreign matter detecting device detects the mud concentration when mud adheres to the surface 11a of the window glass 11 as foreign matter, that is, the window glass 11 serving as the reflection surface 11b of the incident light 9. Surface 11a
The reason why the amount of reflected light 10 decreases when muddy water 8 adheres to the surface will be described below. FIG. 3 is an image diagram showing a state of scattering of the evanescent wave electromagnetic field 12.

When the incident light 9 is totally reflected by the reflection surface 11b of the window glass 11, the light field (electromagnetic field) slightly exudes (about the wavelength of light) from the boundary surfaces (11a and 11b) of the window glass 11. It has been known. This exuding light is the evanescent wave electromagnetic field 12. The thickness of the evanescent wave electromagnetic field 12 oozing from the boundary surface is equivalent to one wavelength of light (about 1 μm).

The muddy water 8 is a soil particle 8 as an insoluble component in water.
b is considered to be floating, so if the earth particles 8b are present in the evanescent wave electromagnetic field generation region 12a, the evanescent wave electromagnetic field 12 is disturbed, and the disturbed scattered wave 9c is not reflected toward the photodiode 3, and The light quantity of the divided reflected light 10 is reduced, and the reflected light 10b is reflected as the reduced reflected light 10b. If the soil particles 8b are not present and only water is used, the evanescent wave electromagnetic field 12 is not affected at all.
Non-response to water, incident light 9 is totally reflected reflected light 10a
Becomes Since the scattering of the evanescent wave electromagnetic field 12 becomes more remarkable as the mud concentration is higher, an output of detecting a foreign substance from the foreign substance detector according to the mud concentration (the number of particulate matter) is obtained as shown in FIG. FIG. 4 shows a change in the output of the foreign matter detection device for a mud sample prepared using eight types of JIS test powders (Kanto Rohm).

In addition, in terms of the material of the components of the above-described foreign substance detection device, the prism 4, the transparent adhesive 7, and the window glass 11 have a sufficient spectral transmittance with respect to the wavelength of the incident light 9 of the LED 2, and In order to prevent optical axis deviation and loss, consideration is given to the material so as to make the optical refractive indexes uniform. For example, if the prism 4 is made of glass (refractive index: 1.51) or acrylic resin (1.49), and the transparent adhesive 7 is made of acrylic, the evanescent wave electromagnetic field 12 due to foreign matter can be adjusted to match the material of the window glass 11. Can be accurately detected.

In the present invention, an example is described in which the foreign matter is detected in muddy water. However, any insoluble component (particulate matter) present in water can be detected, not only mud, but also foreign matter. It functions as a surface contamination detector on the surface to be adhered.

Next, a control example of the automatic wiper control device using the foreign matter detecting device capable of detecting the fine particulate matter in the muddy water will be described with reference to FIG. FIG. 5 is a flowchart showing the operation of the automatic wiper control device 1 shown in FIG.

When the switch is selected by the operator to perform the automatic wiper control, the CPU 30 enters the automatic wiper mode (step 100), and firstly makes the LED 2 emit light (step 101). A / D conversion is performed on the output signal obtained by detecting and amplifying the PD output of No. 3 to obtain a sensor signal level L (step 102).

The amount of decrease in the sensor signal level due to mud adhesion with respect to the sensor output level L0 when no mud adheres is obtained and compared with the determination reference value TH1 (step 10).
3).

If the sensor signal decrease amount (L0-L) is equal to or less than TH1, it is determined that mud does not adhere, and START
Return to 0.

If the sensor signal decrease amount (L0-L) is larger than the criterion value TH1, then it is compared with the criterion value TH2 (step 104).

The criterion values TH1 and TH2 satisfy TH1 <TH.
In particular, it is assumed that the determination reference value TH2 is set to a mud concentration at which the mud of the window glass cannot be removed only by the wiper operation and which needs to be washed away with the cleaning liquid.

When the sensor signal decrease amount (L0-L) is less than or equal to the judgment reference value TH2, the concentration of the attached mud is low, and it is judged that the cleaning liquid is unnecessary. Only the wiper motor is driven for about 3 seconds, and the wiper is operated twice. Drop the mud (Steps 108-11
0).

In general, the cycle of the wiper is slightly less than 2 seconds, and when the wiper is driven for about 3 seconds, the wiper operates for one cycle + α. However, once the wiper motor operates halfway, the wiper motor has a mechanism that continues to operate to the stop position. The wiper operates twice without stopping and stops at a predetermined stop position.

If the sensor signal decrease amount (L0-L) is larger than the determination reference value TH2, it is determined that the mud concentration is high enough to need to be flushed with the cleaning liquid, and the cleaning liquid is injected for about 2 seconds (steps 105 to 107). . Thereafter, the wiper is operated twice to remove mud (steps 108 to 110). Then, the process returns to START again (step 100), and thereafter, the above operation is repeated.

According to the automatic wiper control device 1 described above, by injecting the cleaning liquid only when necessary,
It is possible to both secure the visibility and save the cleaning liquid.

A control example different from the automatic wiper control device 1 will be described below. An automatic wiper control device using a conventional raindrop detecting device receives a signal indicating that there is a raindrop from a raindrop detecting unit, and performs control to automatically perform a wiper wiping operation. In the automatic wiper control device of this example, a control example in which the foreign object detection device of the present invention is provided in addition to the functions of the conventional automatic wiper control device will be described below. In particular,
When water is applied to the surface 11a of the window glass 11, only the wiper wiping operation is controlled to be performed automatically. When it is detected that the detection level is higher than a certain set value, the control is performed so that the washer and the wiper wiping operation are simultaneously performed automatically.

The surface 11a of the window glass 11
When a thin muddy water is applied, the foreign matter detection device detects that the foreign matter is present, and when the detection level is lower than a certain set value, only the wiper wiping operation is performed. If, after this wiper wiping operation, foreign matter remains on the surface 11a of the window glass 11, a raindrop detector (not shown) detects a rainfall state (the presence or absence of raindrops) and there is no rainfall. When the state is detected, and when the foreign matter detection device detects contamination by the foreign matter, control is performed so that the washer and the wiper wiping operation are performed simultaneously.

As described above, by applying the foreign object detection device to the automatic wiper control, it is possible to automatically control the wiper wiping in conjunction with the washer, and there is an effect that a good visual field can always be obtained automatically.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram illustrating an example in which a foreign object detection device according to the present invention is applied to an automatic wiper control device 1 of an automobile.

FIG. 2 is a cross-sectional view of the foreign matter detection device of the present invention.

FIG. 3 is an explanatory diagram showing a state of scattering of an evanescent wave electromagnetic field.

FIG. 4 is a characteristic diagram showing a change in output of a mud detection sensor for a mud sample prepared using eight types of JIS test powders (Kanto Rohm).

FIG. 5 is a flowchart showing an operation of the automatic wiper control device shown in FIG. 1;

[Explanation of symbols]

 Reference Signs List 1 auto wiper control device 2 LED (light emitting means) 3 photodiode (light receiving means) 8 muddy water (foreign matter) 9 incident light 10 reflected light 11a window glass surface (foreign matter attached surface) 11b reflecting surface (rear surface) 12 evanescent wave electromagnetic field 30a washer control Unit (washer unit) 30b Wiper control unit (wiper unit) 30c Control unit (control unit) 31 LED drive circuit 32 Detection and amplification circuit 2, 3, 30c, 31, 32 Foreign object detection device

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tsutomu Nakamura 14 Iwatani, Shimowakaku-cho, Nishio-shi, Aichi Prefecture Inside the Japan Automobile Parts Research Institute (72) Inventor Hirotsugu Ishino 1-1-1 Showa-cho, Kariya-shi, Aichi Prefecture F term in DENSO Corporation (reference) 2G051 AA85 AB01 BB01 2G059 AA05 BB08 EE02 GG02 JJ12 KK01 3D025 AA02 AB01 AB02 AC01 AC02 AD02 AD09 AE57 AG42 AG55

Claims (5)

[Claims] 1. A light-emitting unit that emits light toward the back of a detection target to which a foreign substance different from rain and water adheres to the surface, and a light-receiving unit that receives light reflected by the detection target, The incident angle of light from the light emitting means to the detection target,
The angle is set so that even if water adheres to the surface of the detection target, the angle is set so that the light is totally reflected, and the light receiving unit detects the adhesion of the foreign substance to the detection target by receiving the reflected light. Foreign matter detection device. 2. An incident angle of light from the light emitting element is larger than a critical angle so as to totally reflect a particulate matter attached to a surface of the detection target. 3. The foreign matter detection device according to 1. 3. The foreign matter detection device according to claim 1, wherein an incident angle of light from the light emitting element is not less than 62 degrees and less than 90 degrees when the foreign matter is a mixture with water. 4. The foreign matter detection device according to claim 1, provided on the indoor side of a window glass to be detected, a washer means for supplying a cleaning liquid toward the surface of the window glass, and wiping the surface of the window glass. When the foreign object detection device detects dirt due to foreign matter adhering to the surface of the window glass, the wiper unit and the wiper unit are operated to perform wiper wiping in conjunction with the washer. An automatic wiper control device comprising means. 5. The control means for controlling a washer and wiper wiping operation based on an output from the foreign matter detecting device according to a degree of foreign matter adhering to the surface of the window glass. The automatic wiper control device according to claim 4.