U.S. patent application number 12/837407 was filed with the patent office on 2011-01-20 for sensor module.
Invention is credited to PETER VAN GASTEL, IKO LINDIC.
Application Number | 20110012624 12/837407 |
Document ID | / |
Family ID | 43127261 |
Filed Date | 2011-01-20 |
United States Patent
Application |
20110012624 |
Kind Code |
A1 |
GASTEL; PETER VAN ; et
al. |
January 20, 2011 |
SENSOR MODULE
Abstract
A capacitive sensor module with a sensor electrode which is used
to detect the entry of an object into a space ahead of the sensor
electrode, wherein the sensor electrode is formed from a wire.
Parallel to the sensor electrode, auxiliary electrodes extend
within a plastic carrier that possesses recesses to receive the
sensor electrode and the auxiliary electrodes and partially
surrounds them along their circumference. The sensor electrodes can
be pressed into the plastic carrier by overcoming an elastic
forming force and are held within their recesses by the elastic
reshaping process.
Inventors: |
GASTEL; PETER VAN;
(SOLINGEN, DE) ; LINDIC; IKO; (ESSEN, DE) |
Correspondence
Address: |
BLAKELY SOKOLOFF TAYLOR & ZAFMAN LLP
1279 OAKMEAD PARKWAY
SUNNYVALE
CA
94085-4040
US
|
Family ID: |
43127261 |
Appl. No.: |
12/837407 |
Filed: |
July 15, 2010 |
Current U.S.
Class: |
324/686 |
Current CPC
Class: |
B60R 19/48 20130101;
H03K 17/955 20130101 |
Class at
Publication: |
324/686 |
International
Class: |
G01R 27/26 20060101
G01R027/26 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 20, 2009 |
DE |
10 2009 027 851.6 |
Dec 17, 2009 |
DE |
10 2009 059 202.4 |
Claims
1. Capacitive sensor module with a sensor electrode which is used
to detect the entry of an object into a space ahead of the sensor
electrode, wherein the sensor electrode is formed from a segment of
a first cable or wire, at least one auxiliary electrode which
extends parallel to the sensor electrode, wherein the auxiliary
electrode is formed from a segment of a second cable or wire, a
plastic carrier which has recesses to receive and guide the sensor
electrode and auxiliary electrodes, wherein the recesses are formed
so that they at least partially surround the electrodes along their
circumference and hold them within the recess, wherein the plastic
carrier and the sensor electrode as well as the auxiliary
electrodes are matched to each other in their dimensions and
materials so that the electrodes can be pressed into the applicable
recesses by overcoming an elastic forming force and are held in
their recesses by the elastic reshaping process.
2. Capacitive sensor module in accordance with claim 1, also with a
second auxiliary electrode extending parallel to the first
auxiliary electrode and sensor electrode, wherein the sensor
electrode, first auxiliary electrode and second auxiliary electrode
are arranged in this order and in a straight line.
3. Capacitive sensor module in accordance with claim 2, wherein the
first, outer recess is provided to receive the sensor electrode and
this has a distance to the adjacent recess for the first auxiliary
electrode which is greater than the distance between the recess for
the first auxiliary electrode and the recess for the second
auxiliary electrode.
4. Capacitive sensor module in accordance with claim 1, wherein at
least one of the electrodes is formed from a mantled cable, wherein
the mantle is formed from an elastic soft plastic.
5. Capacitive sensor module in accordance with claim 1, wherein the
carrier possesses a holding segment and an integrally connected
fastening segment, wherein the recesses for the electrodes are
arrayed in the holding segment.
6. Capacitive sensor module in accordance with claim 5, wherein a
clamp that is provided for fastening grasps around the fastening
segment, wherein the fastening segment can be detachably clipped
into the clamp.
7. Capacitive sensor module in accordance with claim 1, wherein the
carrier is integrally formed with a component of a bumper for a
motor vehicle.
8. Capacitive sensor module in accordance with claim 1, wherein a
control and evaluation circuit is linked to the sensor electrode
and detects a capacity change in the capacity of the sensor
electrode as compared to a reference potential by periodically
charging and discharging the sensor electrode with a predetermined
frequency and evaluating at least one parameter of a current or
voltage progression that is dependent on the periodic charging and
discharging of the sensor electrode in order to detect the capacity
change.
9. Capacitive sensor module in accordance with claim 8, wherein the
first auxiliary electrode is connected to the sensor electrode via
the control and evaluation circuit so that its potential largely
follows the potential of the sensor electrode.
Description
BACKGROUND OF THE INVENTION
[0001] The invention involves a sensor module for use in or on
motor vehicles.
[0002] The invention particularly involves a sensor module with a
sensor electrode which will be used in order to prevent the entry
of an object into a space ahead of the sensor electrode. At least
one auxiliary electrode extends parallel to the sensor
electrode.
[0003] Such sensor arrays are used in vehicles within various
fields.
[0004] A capacitive sensor array with a sensor electrode with whose
aid the approach of an object is to be detected, and with a control
and evaluation circuit that is linked to the sensor electrode and
detects a capacity change of the sensor electrode as compared to
mass by periodically linking the sensor electrode with an operating
voltage at a predetermined frequency and evaluating at least one
parameter of a current or voltage progression that is dependent on
the periodic charging and discharging of the sensor electrode in
order to detect the capacity change is, for example, known in the
U.S. Pat. No. 5,730,165 as well as the corresponding patent
document DE 196 81 725 B4. The parameter of a current or voltage
progression that is dependent on the periodic charging and
discharging of the sensor electrode herein consists of a voltage
that can be measured over a condenser and depends on a charge that
is accumulated in the condenser, wherein this charge is accumulated
by periodically charging the sensor electrode by linking it to the
operating voltage and subsequently discharging it again by
connecting it to the condenser. Another such capacitive sensor is
known from the patent document EP 1 339 025 B1.
[0005] A capacitive sensor array with a sensor electrode, with a
mass background electrode that is mounted with a gap behind the
sensor electrode, and with a shielding electrode that is arrayed
between the sensor electrode and the mass background electrode and
is linked to the sensor electrode via a control and evaluation
circuit in such a manner that its potential follows the potential
of the sensor electrode is, for example, known from the
publications EP 0 518 836 A1, U.S. Pat. No. 6,825,752 52, DE 101 31
243 C1 and DE 10 2006 044 778 A1. The provision of an shielding
electrode between the sensor electrode and the background electrode
that is on mass potential as known from these printed documents has
the advantage that the sensitivity of the capacitive sensor that is
formed in this manner towards changes in the space ahead of the
sensor electrode, e.g. by the introduction of objects, is
heightened. This is particularly due to the fact that the field
which spreads out from the sensor electrode ranges more strongly
into the space ahead of the sensor electrode (detection range)
because a large part of the field is no longer short circuited to
the background electrode that is connected to mass potential, as
would be the case if there were no shielding electrode. Due to the
circumstance that the shielding electrode is connected to the
sensor electrode in such a manner that it follows its potential, a
strong electrical field is formed between the shielding electrode
and the background electrode; specifically, however, practically no
field is formed between the sensor electrode and the shielding
electrode whose potential follows.
[0006] The known arrangement of a sensor electrode, shielding
electrode and background electrode is commonly surrounded with an
electrical insulator, such as a plastic layer, so that an
insulating layer, such as a plastic layer, is present on the sensor
electrode and therefore between the sensor electrode and the space
to be monitored ahead of the sensor electrode, namely the detection
zone.
[0007] The production and maintenance of such sensor arrays is
difficult and costly. Particularly the orientation of the
electrodes towards each other and the permanent fixation of the
orientation throughout their entire length, even during operation,
are critical factors.
SUMMARY OF THE INVENTION
[0008] The invention is therefore based upon the task of enabling a
more cost effective and more robust structure in a sensor array of
the initially described variety.
[0009] The invention solves this task with a sensor array
possessing the attributes of claim 1.
[0010] The capacitive sensor array in accordance with the invention
possesses a sensor electrode which can be used to detect the entry
of an object into a space ahead of the sensor electrode. The sensor
electrode is formed from a segment of a first cable or wire. At
least one auxiliary electrode extends parallel to the sensor
electrode, wherein the first auxiliary electrode is formed from a
segment of the second cable or wire.
[0011] A plastic carrier has recesses to receive and guide the
sensor electrode, wherein at least one longitudinally shaped recess
is formed to receive one sensor electrode. Within the recesses, the
sensor electrodes are at least partly surrounded by the plastic
carrier along their circumference and thereby held within the
recess. The plastic carrier and the limits of the recesses are
formed and matched to the sensor electrodes in terms of their
shaping and material selection so that the sensor electrodes can be
pressed into the recesses by application of an elastic or plastic
forming force and are held within their recesses by the elastic
reshaping processes.
[0012] Depending on whether the sensor electrodes are mantled
cables or wires, part or the entire forming process may take place
within the cables, or both the plastic carrier material and the
cable, or only the plastic carrier material, may be formed.
[0013] The invention therefore provides a sensor module which
allows the formation of a sensitive capacitive proximity sensor in
a simple manner and from separate components. The sensor electrodes
are pressed into the carrier material as cables or wires and kept
at a defined distance from each other within it. Stable intervening
spaces and orientation are ensured throughout the entire mounting
distance with the carrier material in accordance with the
invention. Due to the carrier forming process, it is possible to
guide the sensor electrodes reproducibly and precisely within a
desired arrangement and orientation towards each other.
[0014] The embodiment with separate components for the sensor
electrodes on the one hand and the carrier material on the other
hand allows very effective production. The carrier can be commonly
produced by extrusion from a suitable plastic material, while the
cables or wires are available mass wares. The individual components
are easily combined with each other and also easily separated from
each other again, which simplifies repair in case of defects.
[0015] Depending on requirements, the recesses can be formed so as
to be safeguarded against confusion, e.g. with differing sizes for
different wire or cable diameters. In this manner, the sensor
electrode and auxiliary electrodes may be formed from differing
cable types. Due to the specified mount recess, the possibility of
switching cables during assembly is largely excluded.
[0016] In accordance with the invention, the carrier may be formed
as a straight lined body with parallel straight lined wiring
segments. However it is also possible to form the carrier with a
bend or arch, for example if the sensor module is to be used in
correspondingly formed parts of a motor vehicle.
[0017] In accordance with a preferred embodiment, not only a sensor
electrode and a first auxiliary electrode are built into the
carrier, but an additional auxiliary electrode is also intended to
be mounted. In this manner, an initially explained array with a
sensor electrode, shielding electrode (first auxiliary electrode)
and background electrode (second auxiliary electrode can be built.
Herein the electrodes are commonly held in corresponding recesses
in a straight lined arrangement.
[0018] The three electrodes which lie beside each other or behind
each other preferably have varying gaps, wherein the sensor
electrode is farther away from the two auxiliary electrodes than
the two auxiliary electrodes from each other. In other words, there
is a larger distance between the sensor electrode and the shielding
electrode than between the shielding electrode and the background
electrode.
[0019] In a further embodiment, at least one of the electrodes is
formed from a mantled cable. It is fundamentally possible to form
one or more of the electrodes from wires in order to influence the
spread and detection of electrical fields to the lowest possible
degree. However mantled cables are preferably used, due to the
simplicity of handling, robustness and their insensitivity to
environmental influences.
[0020] In a preferred embodiment, the carrier possesses a holding
segment and a fastening segment, wherein the holding segment is
intended to hold the various electrodes and has the corresponding
recesses. The fastening segment is used to position and fasten the
sensor module in its intended location, for example on the inside
of a bumper in a motor vehicle. The fastening segment may have
fastening elements for this purpose. Alternatively the fastening
segment may be glued in at its intended location.
[0021] A preferred mode of fastening the sensor module is by using
a clip provided at the intended location which is able to grasp
around the fastening segment on the sensor module, so that the
sensor module is held within the clip in a stable but detachable
manner. For this purpose, the clip may be formed e.g. from spring
steel or an elastic plastic material.
[0022] In a further embodiment, the carrier is integrally formed
with a corresponding component of a motor vehicle, such as a
bumper. A segment of the corresponding motor vehicle component then
has the recesses into which the sensor electrodes are embedded. In
this manner, it is possible to provide appropriate recesses within
all components of a series, but to provide the corresponding
electrodes and circuits only in those places where this function is
actually desired in the respective vehicle.
[0023] Advantageous and/or preferred embodiments are described in
the Sub-Claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The invention is now explained in further detail using the
included figures.
[0025] FIG. 1 shows the carrier of a sensor module in accordance
with the invention in a first embodiment;
[0026] FIG. 2 shows a frontal view of a sensor module in accordance
with the invention;
[0027] FIG. 3 shows the sensor module from FIG. 2 in a perspective
view;
[0028] FIG. 4 shows a schematic view of the connection of the
sensor module to a control and evaluation circuit.
DETAILED DESCRIPTION OF THE INVENTION
[0029] FIG. 1 shows a carrier 1 which possesses a fastening segment
2 and a mount segment 3. The mount segment 3 contains recesses 4A,
4B, 4C which serve to receive the electrodes. The carrier 1 is
formed as an extrusion body out of plastic. The recesses 4A, 4B, 4C
each possess circular empty spaces within their cross-sections,
which are opened along a circular segment. Cables or wires can be
pressed in through these openings to be held within the
recesses.
[0030] FIG. 2 shows the carrier with inserted electrodes 5A, 5B and
5C as well as a fastening clip 6.
[0031] The electrode 5A is placed in the recess 4A, the electrode
5B in the recess 4B, and the electrode 5C in the recess 4C.
[0032] The clip grasps around the fastening segment 2, fixing it
firmly in place. The clip 6 has suitable elasticity and angled
receiving edges in order to allow easy insertion of the fastening
segment 2 into the clip 6.
[0033] This view shows that the wires or cables 5A, 5B, 5C are held
in their respective inserted positions, since they are grasped
along their circumference to more than half of their circumference.
Even though the cables are equidistantly arranged in this example,
distribution with differing gaps can be implemented without
problems. Differing wire thicknesses can also be used without
difficulty.
[0034] FIG. 3 shows the arrangement from FIG. 2 in a perspective
view, wherein the cables or wires 5A, 5B, 5C are partly brought out
of the carrier. The control and evaluation electronics are
connected in this segment.
[0035] FIG. 4 shows a principle diagram of the corresponding
switching of the sensor module in accordance with the invention.
The electrode 5A as the second auxiliary electrode or background
electrode is connected to the control circuit 10 and lies on mass
potential. The electrode 5B is the active shielding electrode or
first auxiliary electrode and is likewise connected to the control
circuit 10. The sensor electrode 5C is arranged adjacent to the
fastening segment 2 and also connected to the control circuit
10.
[0036] In such a structure, the electrode would, during
installation into a vehicle, be oriented, for example, so that the
clip 6 is arranged on the inside of a bumper, so that the electrode
5A faces the vehicle. The sensor electrode 5C then faces the bumper
side and can, for example, detect the approach of a user's legs or
feet. In this manner, for example, it is possible to detect the
approach of feet in the area below a bumper to trigger automatic
opening of a rear hatch in the vehicle.
[0037] A corresponding arrangement of the exemplary embodiment
within a bumper is shown in FIGS. 5A and 5B. Two sensor modules are
arranged within the inside of a bumper that faces the road-side
covering.
[0038] The control and evaluation circuit 10 detects a capacity
change in the capacity of the sensor electrode 5C as compared to a
reference potential by periodically charging and discharging the
sensor electrode with a predetermined frequency and evaluating at
least one parameter of a current or voltage progression that is
dependent on the periodic charging and discharging of the sensor
electrode in order to detect the capacity change. The periodic
charging and discharging is, for example, implemented by
periodically connecting the sensor electrode 5C at the
predetermined frequency to a specified potential, such as the
operating voltage potential. The voltage progression may, for
example, consist of the voltage progression at the connection of
the sensor electrode. The parameter may, for example, consist of a
voltage that is measured over a condenser that accumulates a
charge, or a specific number of periods of charging and discharging
until a switching threshold is exceeded by a voltage measured at
the sensor electrode. The shielding electrode 5B is connected to
the sensor electrode via the control and evaluation circuit in such
a manner that its potential largely follows the potential of the
sensor electrode. The connection takes place so that the shielding
electrode 5B has no influence on the capacity change in the sensor
electrode that is measured in comparison to the reference
potential. The term of "following" herein aims to describe that the
potential of the shielding electrode 5B must not necessarily be
equal to the potential of the sensor electrode 5C, and that there
may be a time delay between the progression of the potential of the
sensor electrode and the potential of the shielding electrode. The
word "largely" furthermore intends to express that the shielding
electrode does not have to follow the potential of the sensor
electrode throughout the full periods of charging and discharging
the sensor electrode; it is sufficient for it to follow this
potential at least in partial segments of the periods, for example
that it follows the potential of the sensor electrode while the
sensor electrode charges, and drops to mass potential while the
sensor electrode discharges, while the potential of the sensor
electrode still remains at a potential that differs from mass.
[0039] The background electrode is, for example, set to a constant
potential such as mass or operating voltage. Alternatively, the
background electrode may be periodically placed on mass and another
potential, such as the operating voltage, at the specified
frequency, wherein this should preferably occur in a complementary
relation to the sensor electrode, as it is, for example, described
in the parallel pending patent application by the Applicant with
the title "Capacitive sensor array with a sensor electrode, a
shielding electrode and a background electrode". The detection area
of the sensor array, originating from the sensor electrode 4C,
extends into an angle area which faces away from the shielding
electrode 5B.
[0040] The entire array or individual electrodes may be surrounded
by insulator materials. A plastic layer that surrounds the sensor
electrode may be provided particularly between the sensor electrode
and the detection area. It is particularly advantageous if this
layer is surrounded by a first thickness and an outer plastic layer
of a second thickness that is arranged at a specified distance,
wherein the insulator materials are arranged so that the relative
dielectricity constant initially assumes a relatively high value of
the surrounding plastic layer as the distance from the sensor
electrode increases, then drops to a value that approaches the
value of 1 (for example, the value of air) and then rises again to
a relatively high value of the outer plastic layer.
[0041] It was shown that when a space was specifically created
between the plastic layer that forms the outer surface which may be
contaminated by environmental influences and the plastic layer that
surrounds the sensor electrode with a dielectricity constant that
approximates the value of 1, it was possible to reduce or avoid the
interfering influences of moisture contamination. Corresponding
additional layers can be applied e.g. using common coating
procedures in the completion of assembly.
[0042] Numerous variations are possible within the scope of the
invention. In particular, the plastic carrier can be designed as
desired, e.g. with further fastening segments, with mechanical
stabilization braces or thickened areas, or from a variety of
materials. It is significant that the carrier has recesses into
which the wires or cables can be placed to form sensor or auxiliary
electrodes, and in which they are held.
[0043] In principle, it is also possible to form carriers whose
number of recesses exceeds the number of electrodes which will be
used in an application. For instance, it would then be possible to
form universal carriers in which sensor cables are placed at
differing intervals as needed, or sensor cables with differing
cross-sections are placed. The same carrier can then be used to
form different sensor arrays.
* * * * *