U.S. patent application number 09/881078 was filed with the patent office on 2001-11-15 for method for detecting and localizing diffuse reflecting coatings situated on a translucent pane.
This patent application is currently assigned to Leopold Kostal GmbH & Co.KG. Invention is credited to Blasing, Frank.
Application Number | 20010040677 09/881078 |
Document ID | / |
Family ID | 7891464 |
Filed Date | 2001-11-15 |
United States Patent
Application |
20010040677 |
Kind Code |
A1 |
Blasing, Frank |
November 15, 2001 |
Method for detecting and localizing diffuse reflecting coatings
situated on a translucent pane
Abstract
The invention relates to a method and device for detecting and
localizing diffuse-reflecting coatings situated on a translucent
pane and to a corresponding device. The aim of the invention is to
make it possible to detect any diffuse-reflecting coatings in a
non-contacting manner and to differentiate between coatings
situated on the surface facing the sensor and those situated on the
surface facing away from the sensor. To this end an image of an
object is captured by means of a recording unit forming part of the
device by positioning the pane in the optical path between the
object and recording unit, after which the image information
obtained is evaluated accordingly.
Inventors: |
Blasing, Frank; (Werl,
DE) |
Correspondence
Address: |
James N. Kallis
Brooks & Kushman P.C.
1000 Town Center, 22nd Floor
Southfield
MI
48075-1351
US
|
Assignee: |
Leopold Kostal GmbH &
Co.KG
Ludenscheid
DE
|
Family ID: |
7891464 |
Appl. No.: |
09/881078 |
Filed: |
June 13, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09881078 |
Jun 13, 2001 |
|
|
|
PCT/EP99/09944 |
Dec 15, 1999 |
|
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Current U.S.
Class: |
356/239.1 |
Current CPC
Class: |
B60S 1/0822 20130101;
G01N 21/4738 20130101; B60S 1/0844 20130101; B60S 1/0837
20130101 |
Class at
Publication: |
356/239.1 |
International
Class: |
G01N 021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 17, 1998 |
DE |
198 58 316.8 |
Claims
What is claimed is:
1. A method for detecting and localizing coatings on inner and
outer surfaces of a translucent pane using a light source and an
optical sensor array each positioned adjacent the inner side of the
translucent pane, the method comprising: transmitting a light beam
from the light source to the translucent pane; focusing a first
light beam part reflected from the inner surface of the translucent
pane to form a first image on the optical sensor array; focusing a
second light beam part reflected from the outer surface of the
translucent pane to form a second image on the optical sensor
array; comparing an intensity profile of the first image to a first
reference intensity profile indicative of the absence of coatings
on the inner surface of the translucent pane; comparing an
intensity profile of the second image to a second reference
intensity profile indicative of the absence of coatings on the
outer surface of the translucent pane; generating a first signal
indicative of the absence of coatings on the inner and outer
surfaces of the translucent pane if the intensity profile of the
first image matches the first reference intensity profile and the
intensity profile of the second image matches the second reference
intensity profile; generating a second signal indicative of the
absence of coatings on the inner surface of the translucent pane
and the presence of coatings on the outer surface of the
translucent pane if the intensity profile of the first image
matches the first reference intensity profile and the intensity
profile of the second image is different than the second reference
intensity profile; and generating a third signal indicative of the
presence of coatings on the inner surface of the translucent pane
if the intensity profile of the first image is different than the
first reference intensity profile.
2. The method of claim 1 wherein: comparing includes comparing
slopes of the intensity profiles of the first and second images to
slopes of the first and second reference intensities.
3. The method of claim 1 further comprising: performing an action
in response to generation of the second or third signal.
4. The method of claim 3 wherein: performing includes operating an
air-conditioning system arranged on the inner side of the
translucent pane in response to the second signal being
generated.
5. The method of claim 3 wherein: performing includes operating a
windshield wiper system arranged on the outer side of the
translucent pane in response to the third signal being
generated.
6. The method of claim 1 wherein: the translucent pane is an
automobile windshield.
7. A device for detecting and localizing coatings on inner and
outer surfaces of a translucent pane, the device comprising: a
light source positioned adjacent the inner surface of the
translucent pane, the light source operable for transmitting a
light beam to the translucent pane; an optical sensor array
positioned adjacent the inner side of the translucent pane; and a
receiving unit for focusing a first light beam part reflected from
the inner surface of the translucent pane to form a first image on
the optical sensor array and for focusing a second light beam part
reflected from the outer surface of the translucent pane to form a
second image on the optical sensor array; wherein the receiving
unit compares an intensity profile of the first image to a first
reference intensity profile indicative of the absence of coatings
on the inner surface of the translucent pane and compares an
intensity profile of the second image to a second reference
intensity profile indicative of the absence of coatings on the
outer surface of the translucent pane; wherein the receiving unit
generates a first signal indicative of the absence of coatings on
the inner and outer surfaces of the translucent pane if the
intensity profile of the first image matches the first reference
intensity profile and the intensity profile of the second image
matches the second reference intensity profile; wherein the
receiving unit generates a second signal indicative of the absence
of coatings on the inner surface of the translucent pane and the
presence of coatings on the outer surface of the translucent pane
if the intensity profile of the first image matches the first
reference intensity profile and the intensity profile of the second
image is different than the second reference intensity profile;
wherein the receiving unit generates a third signal indicative of
the presence of coatings on the inner surface of the translucent
pane if the intensity profile of the first image is different than
the first reference intensity profile.
8. The device of claim 7 wherein: the light source includes a
light-emitting diode.
9. The device of claim 7 wherein: the light beam transmitted by the
light source is an infrared light beam.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation of International Application
PCT/EP99/09944, with an international filing date of Dec. 15,
1999.
TECHNICAL FIELD
[0002] The invention has as its object a method for detecting the
presence and the relative position of a diffuse reflecting coating,
such as a film of moisture, on the surface of a translucent medium
and a device for implementing the method.
[0003] Used, e.g., in vehicle windshields, such a method can be
seen as the central function of a system for determining the degree
of visibility.
BACKGROUND ART
[0004] The methods known until now for this purpose are based
primarily on sensors that detect a film of moisture on a surface by
means of a capacitive or resistive operating principle and that
must be thermally coupled to said surface in order to achieve the
same coating behavior as the surface being monitored.
[0005] Thus, e.g., a circuit arrangement for measuring moisture on
the windshield of a vehicle is disclosed in DE 44 28 111 A1, in
which the resistance between electrodes on the windshield which are
in thermal contact with it is measured.
[0006] Detection of other coatings than those caused by moisture
and detection of coatings on the surface opposite the sensor cannot
be realized with methods of this previously known type.
[0007] In addition, a device and a method for detecting the
presence and the relative position of coatings on a translucent
pane are known from U.S. Pat. No. 4,867,561. Here, an optical
sensor array with light from various light sources is applied,
wherein these lights sources are arranged in two rows in order to
be able to focus light reflected at various boundary surfaces of
the pane uniformly on the sensor array. The presence of coatings is
evaluated by means of the intensity of the light reflections caused
by the various light sources, wherein, in order to normalize the
absolute intensities, a region of sensor arrays is included that
are not assigned to any light source.
[0008] Because of the number of light sources used in this method,
both the device and the method are very expensive. Thus, the light
sources involve a significant component cost, not only because of
the number of light sources, but also because light sources must be
chosen that generate approximately equal light intensities under
equal power in order for the method based on intensity values to be
implemented. Otherwise, the method must provide for a balancing of
light sources of unequal intensity by individual adjustment of
power to the light sources.
SUMMARY OF THE INVENTION
[0009] Starting from the state of the art, the present invention is
based on the problem of providing a device and method with which,
despite its lower cost, is able to detect and localize any diffuse
reflecting coating without contact and thus avoid the problems
discussed above.
[0010] According to the invention, the problem concerning the
method is solved by a process for the detection and localization of
diffuse reflecting coatings on a translucent pane through the use
of an optical sensor array that contains a receiving unit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Additional particularly advantageous embodiments of the
object according to the invention will be explained using the
embodiment example represented in the drawings.
[0012] Shown are:
[0013] FIG. 1, a schematic representation of a device according to
the invention to illustrate the relationships in a pane that is dry
and clean on both sides;
[0014] FIG. 2, a schematic representation of a device according to
the invention to illustrate the relationship when a coating is
present on the outer side of the pane or the side away from the
sensor; and
[0015] FIG. 3, a schematic representation of a device according to
the invention to illustrate the relationship when a coating is
present on the inner side of the pane or the side facing the
sensor.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0016] As can be seen from FIG. 1, a first part 2a of the beam 2
emitted from a light source 1, and reflected by the surface 3' of
the pane 3 called the inner surface below incident on the receiving
unit 4. Through this first part 2a of the beam, a first image 8 of
the light source 1 is formed at point 8' in the plane of the sensor
array 7 by means of display optics including a diaphragm 5 and a
collecting lens 6.
[0017] A second part 2b of the beam is refracted at the surface 3'
and penetrates into the pane 3. At the opposite surface 3" of the
pane 3, also called the outer surface below, a part 2c of the beam
is reflected, from where, in turn, a part 2d, after another
refraction at the first surface 3', arrives at the receiving unit 4
and generates there a second image 9 of the light source 1 at point
9' in the plane of the sensor array 7.
[0018] As shown by FIG. 2, with a coating 10 on the outer side 3",
a sharp image 8 of the light source 1 is received, in contrast,
only at point 8', which is generated on the inner side 3' by the
part 2a of the beam 2. On the outer side 3" of the pane, the beam
2b that penetrates into the pane is scattered back diffusely or
amplified and passes to the outside. The part 2d' of the beam 2c'
that is radiated back diffusely, which still reaches the receiving
unit 4 after another refraction at surface 3', is no longer able to
generate a sharp image of the light source 1 at point 9', but only
a blurred light spot 9a, which can be distinguished unambiguously
from the sharp image 9 by means of the intensity profile at its
edges, i.e., especially by means of the flat slope of this profile,
in the case shown in FIG. 1.
[0019] The behavior is similar in the situation shown in FIG. 3 of
a coating 11 on the inner surface 3', but in this case a diffuse
scattering of the beam 2 occurs at this surface 3'. The part 2a' of
the beam that goes from the inner side 3' of the pane to the
receiving unit 4 no longer generates a sharp image of the light
source 1 at point 8', but only a blurred light spot 8a, which, like
the situation described previously for the light spot 9a FIG. 2,
and can be distinguished from the sharp image 8 in the case shown
in FIG. 1 by means of the intensity profile at its edges. The part
2d' of the beam 2 that reaches the receiving unit 4 after
reflection at the outer side 3" of the pane and repeated diffuse
scattering at the inner side 3' has lost so much of its original
intensity and characteristic direction that no cohesive localizable
light spot is even formed at point 9' in the plane of the sensor
array 7.
[0020] The method according to the invention for evaluating the
status of a coating on a pane (3) evaluates the intensity profile
currently emitted by the sensor array (7), at which time it is
compared with the intensity profile expected at the known points
(8',9'), which has been stored as a reference for the state without
a coating in order to draw a conclusion about the status of the
coating described above from changes in the profile.
[0021] When the aforementioned method and device are used in a
vehicle, an action control connected after it can trigger various
actions on the basis of the existing status of the vehicle, such as
applying the air-conditioning system to remove the film of moisture
on the inside of the pane and/or the windshield wipers to remove
moisture from the exterior side of the pane.
* * * * *