U.S. patent application number 14/757482 was filed with the patent office on 2016-04-28 for method and device for detecting rain on a windshield.
The applicant listed for this patent is Hella KGaA Hueck & Co.. Invention is credited to Cevin Czsich, Olaf Ludtke, Thomas Niemann, Jurgen Palloks, Almut Schlarmann, Jorg Sturmann.
Application Number | 20160114764 14/757482 |
Document ID | / |
Family ID | 48464610 |
Filed Date | 2016-04-28 |
United States Patent
Application |
20160114764 |
Kind Code |
A1 |
Niemann; Thomas ; et
al. |
April 28, 2016 |
Method and device for detecting rain on a windshield
Abstract
In a method for detecting rain on a windshield, whose degree of
wetting is determined with at least one sensor value, it is
provided that the sensor value is determined piezoelectrically,
wherein vibrations on the windshield are detected, which change
depending on the degree of wetting or raindrops hitting the
windshield. As a result, the entire windshield serves as a
detection surface, thereby yielding a high accuracy.
Inventors: |
Niemann; Thomas;
(Delmenhorst, DE) ; Ludtke; Olaf; (Vollersode,
DE) ; Schlarmann; Almut; (Bremen, DE) ;
Palloks; Jurgen; (Westerstede, DE) ; Czsich;
Cevin; (Bremen, DE) ; Sturmann; Jorg; (Bremen,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hella KGaA Hueck & Co. |
Lippstadt |
|
DE |
|
|
Family ID: |
48464610 |
Appl. No.: |
14/757482 |
Filed: |
December 23, 2015 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
13712058 |
Dec 12, 2012 |
|
|
|
14757482 |
|
|
|
|
Current U.S.
Class: |
73/658 |
Current CPC
Class: |
G01N 2291/02809
20130101; B60S 1/0859 20130101; G01N 29/2437 20130101; B60S 1/0491
20130101; G01W 1/14 20130101 |
International
Class: |
B60S 1/08 20060101
B60S001/08; G01N 29/24 20060101 G01N029/24 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 12, 2011 |
DE |
10 2011 120 867.8 |
Claims
1. A method for detecting rain on a windshield, comprising
detecting vibrations on the windshield, caused by rain, with a
piezoelectric sensor, the vibrations being detected via at least
one wiper blade of a windshield wiper system, and via a coupling
between the at least one wiper blade and the windshield,
determining a sensor value from the output of the piezoelectric
sensor, which depends on the degree of wetting or raindrops hitting
the windshield, comparing the sensor value with known vibration
profiles, and determining the environmental condition on the
windshield, caused by the rain, from said comparing.
2. The method according to claim 1, wherein a distribution profile
is established for the degree of wetting given at least two sensor
values detected at locations spaced apart from each other.
3. A device for detecting rain on a windshield, comprising: a
windshield wiper system of the windshield, at least one wiper blade
included in said windshield wiper system, at least one rain sensor
included in the windshield wiper system includes at least one piezo
element, the at least one wiper blade includes one of the at least
one rain sensors having the at least one piezo element, with the
piezo element being coupled to the windshield through the wiper
blade, and an output of the piezo element is compared to stored
vibration profiles to determine the environmental condition on the
windshield caused by rain.
4. The device according to claim 3, wherein the piezo element is
designed as a piezoelectric line, which is attached along a length
of the wiper blade, making the length of the wiper blade a rain
sensor.
5. A motor vehicle, including a device according to claim 3.
6. The device according to claim 3, wherein the piezo element is
heatable in cold weather.
7. The device according to claim 3, wherein the determination of
the environmental condition controls a headlight system.
8. The device according to claim 3, wherein wear on the wiper blade
is determined by the piezo element.
9. The device according to claim 3, wherein movement of the wiper
blade causes the at least one sensor to cover a large portion of
the windshield.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation of co-pending application
Ser. No. 13/712,058, filed Dec. 12, 2012, for which priority is
claimed under 35 U.S.C. .sctn.120, and this application claims
priority of Application No. 10 2011 120 867.8 filed in Germany on
Dec. 12, 2011 under 35 U.S.C. .sctn.119, the entire contents of all
of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a method for detecting rain on a
windshield, whose degree of wetting is determined with at least one
sensor value. In addition, the invention also relates to a device
for detecting rain on a windshield, with at least one rain sensor,
which is allocated to a windshield wiper system for the windshield,
and a motor vehicle with such a device.
[0004] 2. Brief Discussion of the Related Art
[0005] In motor vehicles, rain sensors are most often coupled with
an activation of the windshield wiper system, so that once rain
hitting the windshield has been registered or a predetermined
degree of windshield wetting has been detected, windshield wipers
are automatically activated. The most common rain sensors today are
those based on optoelectric measurement. These rain sensors most
often exhibit at least one light source and at least one detecting
photodiode, wherein the light source sends out an optical signal,
which is reflected in a predetermined detection range on the
windshield, and the reflected optical signal is detected by the
photodiode. A differential value is then derived from the
transmitted and detected optical signal, based upon which the
degree of wetting for the detection range of the windshield is
determined. However, the disadvantage is that the detection range
of the optoelectric rain sensors only detects a small section
usually measuring about 2 cm.sup.2 of the windshield. Therefore,
rain is inaccurately detected primarily at the beginning of
showers, since a larger amount of rain might already have hit the
windshield without the detection range having been sufficiently
wetted. In addition, the spray from oncoming traffic is only
inadequately detected, if at all.
BRIEF SUMMARY OF THE INVENTION
[0006] Therefore, the object of the invention is to develop a rain
sensor having a large surface as the detection range, and a higher
accuracy with respect to the degree of wetting to be detected.
[0007] In terms of the method, the degree of wetting is determined
with at least one sensor value. The sensor value is determined
piezoelectrically, and vibrations on the windshield are detected.
The change depends on the degree of wetting or raindrops hitting
the windshield, and the vibrations on the windshield are detected
via at least one wiper blade of a windshield wiper system and its
coupling to the windshield.
[0008] In terms of the device, the device includes at least one
rain sensor, which is allocated to the windshield wiper system of
the windshield. The rain sensor exhibits at least one piezo
element, and the windshield wiper system has at least one wiper
blade. The wiper blade has the piezo element of the rain
sensor.
[0009] Further scope of the applicability of the present invention
will become apparent from the detailed description given
hereinafter. However, it should be understood that the detailed
description and specific examples, while indicating preferred
embodiments of the invention, are given by way of illustration
only, since various changes and modifications within the spirit and
scope of the invention will become apparent to those skilled in the
art from this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The present invention will become more fully understood from
the detailed description given hereinbelow and the accompanying
drawings which are given by way of illustration only, and thus are
not limitative of the present invention, and wherein:
[0011] The sole figure illustrates a windshield wiper system, in
accordance with the present invention.
DETAILED DISCUSSION OF THE PREFERRED EMBODIMENTS
[0012] In the method for detecting rain on a windshield, whose
degree of wetting is detected with at least one sensor value, the
invention provides that the sensor value is determined
piezoelectrically, wherein vibrations on the windshield are
detected, which change depending on the degree of wetting or
raindrops hitting the windshield.
[0013] According to the invention, the vibrations on the windshield
are detected via at least one wiper blade of a windshield wiper
system and its coupling to the windshield. The detection takes
place by means of a piezoelectric element arranged in the wiper
blade.
[0014] In particular, a changing amplitude in windshield vibration
is detected and evaluated. The windshield typically vibrates at a
characteristic frequency. In a preferred embodiment of the
invention, amplitude patterns intended for different environmental
conditions are stored in a file. These stored amplitude patterns
are compared with the measured amplitude progressions. Based on the
deviations and in particular slight deviations from the stored
patterns, a conclusion can then be reached about a specific type of
environmental conditions, e.g., light rain, strong rain or spray. A
corresponding windshield wiper control action can be derived from
this. As a consequence, the detection range for recognizing rain
advantageously extends over the entire windshield, so that even a
few raindrops are recognized with a high degree of certainty,
regardless of where they hit the windshield, with the same even
holding true for spray that only hits a section of the windshield.
The degree of windshield wetting is here detected by way of the
windshield vibrations triggered by the rain or spray, wherein a
sensor value is piezoelectrically recorded, and used for comparison
to a stored vibration profile.
[0015] Therefore, the degree of wetting, for example when water
and/or similar liquids are present on the windshield, can be
determined regardless of any other dirt on the windshield, which
had previously often led to malfunctions while detecting the degree
of wetting.
[0016] Depending on the determined sensor value, a windshield wiper
system allocated to the windshield is then activated once a
predetermined sensor value has been reached. The windshield wiper
system can wipe the windshield at intervals or continuously,
depending on the intensity of the recognized degree of wetting or
incident raindrops. By contrast, spray hitting the windshield
generates a vibration profile to be differentiated from that
associated with raindrops, so that a single wipe of the windshield
could then take place, for example. The vibration profiles differ
primarily in terms of their amplitude progression and the strength
of the respective vibration amplitudes. The windshield vibrations
can be evaluated especially precisely by generating a distribution
profile for the degree of wetting given at least two sensor values
detected at locations spaced apart from each other. For example,
this makes it possible to localize spray that only hits a section
of the windshield.
[0017] It can also be provided that at least one additional sensor
value is detected, wherein an optical signal is sent out, the
optical signal is reflected on the windshield in a predetermined
detection range, the reflected optical signal is detected, and a
differential value is derived from the transmitted and detected
signal, based upon which the degree of wetting is determined for
the windshield. Rain can be recognized with a high degree of
certainty using the additional sensor value, since two varyingly
configured sensor systems detect the degree of windshield wetting.
The sensor values detected in different ways can also be linked
with a targeted control of the windshield wiper system. For
example, if rain is recognized only with the piezoelectrically
recorded sensor value based on corresponding vibrations, without
rain being recognized with the optoelectric sensor value, the
windshield can be wiped just once for the time being. When the
windshield wiper system is activated for the first time, it is here
advantageously provided that the area of the windshield in which
the optical signal is reflected be wiped especially slowly, and any
water located on the windshield be determined and quantified with
the optical signal in the wiping process. In this way, the
optoelectric sensor value enables a capacitive measurement of water
located on the pane. In combination with the vibrations determined
over a predetermined measuring period, various states or degrees of
wetting can be differentiated from each other, thereby always
ensuring optimal control in the wiping process, and hence an
optimal view through the windshield.
[0018] In another embodiment, the sensor value can also be used for
automatic headlight control, so as to account for visibility and
light conditions, which are often poor in the rain.
[0019] The invention further relates to a device for detecting rain
on a windshield with at least one rain sensor, which is allocated
to a windshield wiper system of the windshield, and distinguished
by the fact that the rain sensor exhibits at least one piezo
element. The piezo element detects windshield vibrations, wherein
steady rain, isolated raindrops or spray from oncoming traffic have
vibration profiles that vary from both one another and other
factors that cause vibrations. These vibrations or vibration
profiles then cause the respective piezo element to become
specifically coupled to the windshield. It is precisely this
coupling of the piezo element to the windshield which is here
detected by the piezo element. In a dry state, the piezo element
exhibits a higher acoustic coupling to the windshield, so that the
vibrations are intensely reflected. By contrast, the piezo element
exhibits a lower acoustic coupling to the windshield in a wet
state.
[0020] In order to detect the vibrations as directly as possible,
it is provided that the piezo element of the rain sensor be
arranged on the outside of the windshield. The arrangement
according to the invention for the piezo element stems from the
fact that the windshield wiper system has at least one wiper blade,
and the wiper blade has the piezo element of the rain sensor. The
piezo element can thus be allocated to the windshield without any
significant added structural outlay, thereby yielding a
particularly inexpensive arrangement. In addition, the rain sensor
is easy to install on a windshield after the fact.
[0021] Arranging the piezo element in a rubber section of the wiper
blade ensures that the piezo element abuts the pane as closely as
possible, wherein the piezo element is at the same time optimally
protected relative to the environment. This prevents any damage to
the piezo element. In addition, arranging the piezo element in the
wiper blade makes it possible to determine wear on the wiper blade,
since the coupling of the piezo element to the windshield also
changes as a function of wiper blade wear.
[0022] A preferred embodiment here provides that the piezo element
be designed as a piezoelectric line, which detects the wiper blade
over its entire longitudinal expansion. As a consequence, the piezo
element extends over as large an area or a large surface of the
windshield, making it possible to recognize and potentially also
localize vibrations with a high level of accuracy. For example,
vibrations exerting a different effect could be used at opposing
ends of the piezo element in order to establish a distribution
profile for the degree of windshield wetting. In particular, motor
vehicles most often have two wiper blades allocated to a
windshield, so that each wiper blade preferably exhibits a piezo
element, and the most uniform possible distribution of piezo
elements is achieved over the entire windshield area.
[0023] In order to help prevent the wiper blades from sticking or
freezing to the windshield during a frost, it is further provided
that the piezo element has a heatable design. Whether or even when
the piezo element is heated is here in turn determined by the
vibrations or specific coupling to the windshield. Heating also
makes it possible to minimize wear on the wiper blade.
[0024] The measuring behaviour of the rain sensor can be improved
by having it also exhibit at least one additional, optoelectric
sensor unit.
[0025] The invention further relates to a motor vehicle, which
exhibits the device described above.
[0026] The invention will be explained below based on an exemplary
embodiment depicted in the drawing.
[0027] The drawing presents a detailed view of a windshield 1 with
a wiper blade 2 of a windshield wiper system 3. This wiper blade 2
has a guide section 4 along with a rubber section 5 moveably held
on the guide section 4. The rubber section 5 is guided along the
windshield 1, pushing away any water 6 located on the windshield 1.
A piezo element is integrated into the rubber section 5 of the
wiper blade 2. The piezo element is used to determine the coupling
of the wiper blade 2 to the windshield 1, and the windshield wiper
system 3 is activated once a predetermined degree of wetting has
been detected.
[0028] The invention being thus described, it will be obvious that
the same may be varied in many ways. Such variations are not to be
regarded as a departure from the spirit and scope of the invention,
and all such modifications as would be obvious to one skilled in
the art are intended to be included within the scope of the
following claims.
* * * * *