U.S. patent application number 12/025955 was filed with the patent office on 2008-05-29 for sensor assembly and method of forming the same.
This patent application is currently assigned to 3M Innovative Properties Company. Invention is credited to Charles MITCHELL, Sywong Ngin.
Application Number | 20080120837 12/025955 |
Document ID | / |
Family ID | 36778177 |
Filed Date | 2008-05-29 |
United States Patent
Application |
20080120837 |
Kind Code |
A1 |
MITCHELL; Charles ; et
al. |
May 29, 2008 |
SENSOR ASSEMBLY AND METHOD OF FORMING THE SAME
Abstract
A sensor assembly includes a sensing element electrically
connected to a conductor of a flexible multiconductor cable using a
conductive patch, which is electrically connected to the conductor.
A method of forming a sensor assembly includes electrically
connecting an electrically conductive patch to a sensing element
and electrically connecting a conductor of a multiconductor cable
to the electrically conductive patch.
Inventors: |
MITCHELL; Charles; (Austin,
TX) ; Ngin; Sywong; (Austin, TX) |
Correspondence
Address: |
3M INNOVATIVE PROPERTIES COMPANY
PO BOX 33427
ST. PAUL
MN
55133-3427
US
|
Assignee: |
3M Innovative Properties
Company
|
Family ID: |
36778177 |
Appl. No.: |
12/025955 |
Filed: |
February 5, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11098322 |
Apr 4, 2005 |
7352191 |
|
|
12025955 |
|
|
|
|
Current U.S.
Class: |
29/857 ;
29/854 |
Current CPC
Class: |
Y10T 29/49174 20150115;
B60N 2/002 20130101; H05K 1/189 20130101; Y10T 29/49169 20150115;
H05K 3/326 20130101 |
Class at
Publication: |
29/857 ;
29/854 |
International
Class: |
H01R 43/00 20060101
H01R043/00 |
Claims
1. A method of forming a sensor assembly, the method comprising:
electrically connecting an electrically conductive patch to a
sensing element; and electrically connecting a
longitudinally-extending conductor of a multiconductor cable to the
electrically conductive patch, thereby forming an electrical
connection between the conductor and the sensing element.
2. The method of claim 1, and further comprising securing a pad
material to at least part of the multiconductor cable.
3. The method of claim 2, wherein the pad material is a foam
material.
4. The method of claim 2, wherein the pad material is secured to at
least part of the multiconductor cable using a means selected from
a group consisting of an adhesive, thermal bonding, or a mechanical
attachment.
5. The method of claim 2, and further comprising: placing a
substantially liquid impervious, vapor permeable material over at
least a portion of the pad material.
6. The method of claim 2, and further comprising: aligning the pad
material in a recess in a vehicle seat assembly; and placing an
outer cover over at least part of the vehicle seat assembly.
7. The method of claim 1, wherein electrically connecting the
longitudinally-extending conductor of the multiconductor cable to
the electrically conductive patch comprises: cutting at least part
of the conductor in a substantially lateral direction; cutting at
least part of the multiconductor cable adjacent the conductor in a
substantially longitudinal direction to form a tab having three
sides which are not connected to the cable, wherein the lateral and
longitudinal directions are substantially perpendicular to each
other, and wherein the tab is capable of protruding from the cable;
and removing an insulating layer from at least part of the tab.
8. The method of claim 7, wherein the insulating layer is removed
from the tab using a means selected from a group consisting of a
laser, heat, and mechanical abrasion.
9. The method of claim 7, and further comprising: securing at least
part of the tab to the electrically conductive patch.
10. The method of claim 1, wherein the cable and the sensing
element are positioned on opposing sides of a pad material, and
wherein at least part of the tab projects through the pad
material.
11. The method of claim 1, wherein the electrically conductive
patch includes a metallized nonwoven material.
12. A method of forming a sensor mat assembly, the method
comprising: providing a first sensing element; electrically
connecting a first electrically conductive patch to the first
sensing element; electrically connecting a first conductor of a
multiconductor cable to the first electrically conductive patch;
securing at least part of a first side of a pad material to the
cable; securing a second sensing element to a second side of the
pad material, wherein the first side of the pad material opposes
the second side; electrically connecting a second electrically
conductive patch to the second sensing element; and electrically
connecting a second conductor of the multiconductor cable to the
second electrically conductive patch.
13. The method of claim 12, wherein electrically connecting the
first conductor to the first conductive patch comprises: cutting at
least part of the first conductor in a substantially lateral
direction; cutting at least part of the multiconductor cable
adjacent the first conductor in a substantially longitudinal
direction to form a tab having three sides which are not connected
to the cable, wherein the lateral and longitudinal directions are
substantially perpendicular to each other, and wherein the tab is
capable of protruding from the cable; and removing an insulating
layer from at least part of the tab.
14. The method of claim 12, wherein electrically connecting the
second conductor to the second conductive patch comprises: cutting
at least part of the second conductor in a substantially lateral
direction; cutting at least part of the multiconductor cable
adjacent the second conductor in a substantially longitudinal
direction to form a tab having three sides which are not connected
to the cable, wherein the lateral and longitudinal directions are
substantially perpendicular to each other, and wherein the tab is
capable of protruding from the cable; and removing an insulating
layer from at least part of the tab.
15. The method of claim 12, wherein the first and second
electrically conductive patches each include a metallized nonwoven
material.
16. The method of claim 12, and further comprising securing a
second side of the pad material to the cable.
17. The method of claim 12, wherein at least part of the first side
of the pad material is secured to the cable using a means selected
from a group consisting of an adhesive, thermal bonding, or a
mechanical attachment.
18. The method of claim 12, and further comprising: placing a
substantially liquid impervious, vapor permeable material over at
least a portion of the pad material.
19. The method of claim 12, and further comprising: aligning the
pad material in a recess in a vehicle seat assembly; and placing an
outer cover over at least part of the vehicle seat assembly.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. Ser. No.
11/098,322, filed Apr. 4, 2005, now allowed, the disclosure of
which is incorporated by reference in its entirety herein.
BACKGROUND
[0002] The present invention relates to a sensor assembly. More
particularly, the present invention relates to a sensor assembly
including a sensing element connected to a conductor of a
multiconductor cable using a conductive patch. In addition, the
present invention relates to a method of forming a sensor
assembly.
[0003] Sensor assemblies may be used to monitor the position,
orientation, presence, or size of a person or object within a
defined space. The position, orientation, presence, or size of a
person or object in the defined space may affect the impedance
around a sensing element of a sensor assembly. A current may be
applied to one or more sensors, and an electronic control unit
("ECU") may measure the impedance changes in an electric field
around each sensing element in order to gather information about
the position, orientation, presence, or size of a person. For
example, a sensor assembly may be used in a vehicle seat to help
regulate the deployment of air bags.
[0004] A sensor assembly generally includes an array of electrode
sensors (or other suitable sensing elements) arranged about the
defined space, where each sensor is electrically connected to the
ECU. Each sensor is typically connected to the ECU using a
conductive wire which is electrically connected to the sensor using
an eyelet and rivet securing means or by "crimping" the sensor and
wire together. Typically, there is one discrete conductive wire per
sensor, and so each sensor assembly has multiple, but separate,
conductive wires. When used in a vehicle seat, the sensors may be
attached to a flexible pad material, such as a polyurethane foam
mat, which may then be used to form part of the vehicle seat.
BRIEF SUMMARY
[0005] In a first aspect, the present invention is a sensor
assembly including a sensing element, an electrically conductive
patch electrically connected to the sensing element, and a cable
including a plurality of conductors. The electrically conductive
patch is positioned between the cable and the sensing element. A
conductor of the cable is electrically connected to the
electrically conductive patch.
[0006] In a second aspect, the present invention is a sensor mat
assembly including a pad material, a first sensing element
electrically connected to a first electrically conductive patch on
a first side of the pad material, a second sensing element
electrically connected to a second electrically conductive patch on
a second side of the pad material, and a flat cable. The first and
second sides of the pad material oppose one another. The flat cable
includes a first conductor and a second conductor. The first
conductor is electrically connected to the first electrically
conductive patch and the second conductor is electrically connected
to the second electrically conductive patch.
[0007] In a third aspect, the present invention is a method of
forming a sensor assembly. The method includes electrically
connecting an electrically conductive patch to a sensing element
and electrically connecting a longitudinally-extending conductor of
a multiconductor cable to the electrically conductive patch,
thereby forming an electrical connection between the conductor and
the sensing element.
[0008] In a fourth aspect, the present invention is a method of
forming a sensor mat assembly. The method includes providing a
first sensing element, electrically connecting a first electrically
conductive patch to the first sensing element, electrically
connecting a first conductor of a multiconductor cable to the first
electrically conductive patch, securing at least part of a first
side of a pad material to the cable, securing a second sensing
element to a second side of the pad material, where the first side
of the pad material opposes the second side, electrically
connecting a second electrically conductive patch to the second
sensing element, and electrically connecting a second conductor of
the multiconductor cable to the second electrically conductive
patch.
[0009] The above summary is not intended to describe each disclosed
embodiment or every implementation of the present invention. The
figures and the detailed description which follow more particularly
exemplify illustrative embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The present invention will be further explained with
reference to the drawing figures listed below, where like structure
is referenced by like numerals throughout the several views.
[0011] FIG. 1 is a perspective view of a sensor mat assembly in
accordance with the present invention, where a sensor array is
arranged on opposing sides of a foam mat and a flat cable
positioned between layers of foam.
[0012] FIG. 2 is an exploded perspective view of a first exemplary
embodiment of a sensor mat assembly in accordance with the present
invention, where a foam mat is positioned between a flat cable and
a sensing element.
[0013] FIG. 3A is a schematic sectional view of the sensor mat
assembly of FIG. 2, as assembled and taken along lines 3-3.
[0014] FIG. 3B is a schematic sectional view of the sensor mat
assembly of FIG. 2, as assembled and taken along lines 3-3, where
an opening in the foam mat has an inclined wall.
[0015] FIG. 4 is an exploded perspective view of a second exemplary
embodiment of a sensor mat assembly in accordance with the present
invention, where a flat cable and a sensing element are positioned
on the same side of a foam mat.
[0016] FIG. 5 is a schematic sectional view of the sensor mat
assembly of FIG. 4, as assembled and taken along lines 5-5.
[0017] FIG. 6 is a bottom view of the sensor mat assembly of FIG. 4
as assembled, from the view shown in FIG. 4, where a plurality of
sensing elements are arranged on the foam mat.
[0018] FIG. 7 is an exploded perspective view of a third exemplary
embodiment of a sensor mat assembly in accordance with the present
invention, which combines aspects of the first and second exemplary
embodiments.
[0019] FIG. 8 is a perspective view of an alternate embodiment of a
flat cable that may be used in accordance with the present
invention, where the unused portions of each conductor are removed
from the flat cable.
[0020] While the above-identified figures set forth several
embodiments of the invention, other embodiments are also
contemplated, as noted in the discussion. In all cases, this
disclosure presents the invention by way of representation and not
limitation. It should be understood that numerous other
modifications and embodiments can be devised by those skilled in
the art, which fall within the scope and spirit of the principles
of the invention.
DETAILED DESCRIPTION
[0021] The present invention is a sensor assembly including a
sensing element, a flexible multiconductor cable, and an
electrically conductive patch, where the electrically conductive
patch electrically connects the sensing element and a conductor of
the cable. The electrically conductive patch is positioned between
the cable and the sensing element. The cable may be used to connect
the sensing element to an ECU. The present invention is also a
method of forming the inventive sensor assembly. Although the
present invention is described in reference to a vehicle seat,
other applications of the present invention in which it may be
desirable to gather information about the position, orientation,
presence, or size of a person within a defined space are also
contemplated.
[0022] A flexible multiconductor cable in accordance with the
present invention is preferably a flexible flat cable. A "flat
cable" is a cable including a plurality of mutually insulated
conductors, where the cable preferably has generally flat top and
bottom surfaces and a non-cylindrical cross-section. The conductors
are preferably aligned in a common plane than being grouped
together or around a common axis to form a circular cross-section.
The conductors are typically bound together (while being aligned in
a common plane), which may increase the structural integrity and
strain relief capabilities of the flat cable. The conductors may be
any suitable shape, such as round or flat. Although a cable having
a cylindrical cross-section may be used with the present invention,
a flat cable is preferred because such a cable may be a more
efficient use of space and a flat cable may be more comfortable to
a vehicle occupant sitting on the vehicle seat.
[0023] A flat cable may also be preferred because of the
substantially constant spacing between the conductors. That is, the
spacing between the conductors of the flat cable remains
substantially consistent because of the insulation material
separating the conductors. The substantially constant spacing may
increase the ability of an ECU, which is connected to the flat
cable, to detect minor changes in impedance around a sensing
element that is electrically connected to the flat cable. A
suitable flat cable may be, but is not limited to, what is commonly
referred to as a "ribbon" cable, which includes round conductors
aligned parallel in a plane. The present invention may also reduce
the number of individual wires required to connect the sensors to
the ECU and simplify the connection process because a single cable
having a plurality of mutually insulated conductors may be
used.
[0024] A sensing element is connected to a conductor of the cable
using a conductive patch, which is positioned between the cable and
sensing element. Preferably, each sensing element is electrically
connected to a separate conductive patch and a separate conductor
of the multiconductor cable so that the ECU is able to gather
information from individual sensing elements. Any suitable sensing
element may be used with the present invention. For example, the
sensing element may be formed of an electrode antenna, as described
in U.S. Pat. No. 6,683,583, entitled, "FLEXIBLE ELECTRODE ANTENNA",
and assigned to 3M Innovative Properties Company, St. Paul, Minn.
Typically, more than one sensing element is used in the sensor
assembly of the present invention (in a "sensor array"). If the
sensor array is used in conjunction with a pad material (e.g., a
foam mat), it may be desirable for sensors to be arranged on two
opposing sides of the pad material. The positioning of each sensing
element in the array may vary depending upon the type of vehicle
the sensor assembly is used in, or the particular application of
the sensor assembly (e.g., whether the sensor assembly is being
used to activate front air bags, side air bags, etc. . . . ).
[0025] As described below, the sensing element may be secured to a
conductive patch using a suitable means, such as an adhesive. In
embodiments where the sensing element is adjacent to the flat cable
of the sensor assembly, the sensing element and flat cable may be
secured together using a transfer adhesive (which is preferably
nonconductive). Other suitable means may also be used to connect
the flat cable and sensing element together. The adhesion of the
flat cable to the sensing element may provide more rigidity and
therefore, integrity, to the sensor assembly than if the flat cable
and sensing element were not adhered together, and the added
rigidity may be preferable it adds to the integrity to the sensor
assembly.
[0026] The conductive patch may be formed out of a conductive
material. The conductive patch may be electrically conductive in
either orthogonal x-y-z coordinate directions (see coordinates
shown in FIG. 1) or in the z-coordinate direction. Examples of
suitable materials for forming a conductive patch include, but are
not limited to, a metallized nonwoven material (e.g., Product No.
9713, which is made commercially available by 3M Company, St. Paul,
Minn.), a double-sided conductive tape (e.g., Product No. 1182,
which is made commercially available by 3M Company, St. Paul,
Minn.), a conductive transfer adhesive, and a conductive carbon
nonwoven material (Product No. 9712, which is made commercially
available by 3M Company, St. Paul, Minn.).
[0027] A conductive patch provides a range of electrical
connectivity points for the sensing element and conductor because
it provides a relatively large target conductive surface for the
conductor relative to the sensor. As a result, alignment of the
sensing element and conductor is not as critical as in known
connection methods. In this way, the conductive patch helps a
single manufacturing process be applicable to a broad range of
vehicle seats rather than being specific to a particular type of
vehicle seat. The conductive patch may also simplify the process
for connecting the sensing element to the conductor of the cable by
enlarging the range of connectivity points, and because a separate
eyelet and rivet connection step between a wire and sensor is no
longer required. The conductive patch may have an adhesive on one
side or both opposing sides in order to help secure the conductor
to the conductive patch, and/or to help secure the sensing element
to the conductive patch. For example, the conductive patch may be
die cut from a roll of conductive material lined with an adhesive,
such as a pressure sensitive adhesive. In one embodiment, the
adhesive may be conductive.
[0028] When used in conjunction with a pad material, such as a foam
mat or any other suitable cushioning material, the present
invention may be characterized as a "sensor mat assembly." The
sensor mat assemblies described below include a foam mat. However,
one skilled in the art may substitute a suitable pad material for
the foam mat (e.g., resiliently deformable), depending upon the
particular application of the sensor mat assembly. The foam mat may
be a formed out of a polyurethane foam, or it may be formed out of
one or more layers of foam having varying thicknesses and varying
densities. The different layers may then be adjusted to a desired
comfort level, or other vehicle-specific parameters. The foam mat
may be part of a vehicle seat assembly. A sensor assembly or a
sensor mat assembly in accordance with the present invention may
have a substantially liquid impervious, vapor permeable material
covering at least apart of the sensor assembly, as described in
U.S. patent application Ser. No. 10/196,997, entitled "BREATHABLE
MOISTURE BARRIER FOR AN OCCUPANT SENSING SYSTEM" and filed on Jul.
16, 2002.
[0029] In embodiments where the foam mat, or other pad material, is
adjacent to the flat cable of the sensor assembly, the foam mat and
flat cable may be secured together using an adhesive. For example,
a transfer adhesive may be applied to opposing sides of a cable,
where one side of the cable adheres to the foam mat, and the
opposing side of the cable may adhere to a substantially liquid
impervious, vapor permeable material. The rigidity and integrity of
the sensor assembly may increase when the flat cable is adhered (or
otherwise secured) to the foam mat and substantially liquid
impervious, vapor permeable material.
[0030] The figures are not drawn to scale. If drawn to scale, each
flat cable would be much thinner (i.e., have a smaller z-coordinate
dimension), because it is preferred that the flat cable have a
small thickness as compared to the thickness of a foam mat so that
the flat cable has a low profile relative to the foam mat and does
not itself protrude from the mat or cause the foam mat to protrude.
As used herein (see FIG. 2), a "length" runs along the x-coordinate
direction, a "width" runs along the y-coordinate direction, and a
"thickness" runs along the z-coordinate direction.
[0031] FIG. 1 is a perspective view of a sensor mat assembly 10 in
accordance with the present invention. Sensor mat assembly 10 shows
a general structure of a sensor mat assembly of the present
invention which may be incorporated into a vehicle seat. Sensor
array 12 is arranged on opposing sides of foam mat 14. Sensor array
12 is formed of a plurality of sensing elements, where a first set
of sensing elements 16 is arranged on one side of foam mat 14,
while a second set of sensing elements 18 (shown in phantom) is
arranged on an opposing side of foam mat 14. Sensing elements 18
may optionally include one or more sensors 181 which may be used to
determine a thickness of foam mat 14. Sensors 181 thereby act as
calibration sensors, which adjust an algorithm used by the ECU for
interpreting impedance changes in each sensor. The algorithm is
adjusted according to changes in the thickness of foam mat 14.
[0032] Each sensing element in first and second sets of sensing
elements 16 and 18 is electrically connected to an ECU (not shown
in FIG. 1) using flat cable 20. Flat cable 20 is formed of a
plurality of longitudinally-extending (i.e., extending in the
x-coordinate direction) conductors insulated from each other by an
insulating material. Preferably, each sensing element in sensor
array 12 is electrically connected to a separate conductor in flat
cable 20. Flat cable 20 is positioned between layers of foam, which
form foam mat 14. Foam mat 14 may be secured to at least part of
cable 20 using a suitable means, such as an adhesive, thermal
bonding, or a mechanical attachment.
[0033] As FIG. 1 shows, flat cable 20 does not protrude
significantly in the z-coordinate direction from foam mat 14,
thereby adding to occupant comfort (when the occupant is sitting on
a vehicle seat that includes sensor mat assembly 10). In current
methods of connecting a sensing element to a wire using an eyelet
and rivet connection, the sensing element does not typically run
the width of the foam mat because the eyelet and rivet connection
is typically connected to one end of sensing element, and that end
of the sensing element is then positioned off to one side of the
foam mat (so that it is no longer centered on the foam mat) so as
not to cause discomfort to a vehicle occupant. In the present
invention, the size of each sensing element may be increased
because each sensing element of flat cable 20 may be run between
foam mat 14 or be positioned underneath foam mat 14, and each
sensing element in first and second sets of sensing elements 16 and
18 (and optional calibration sensors 181) may run the width of foam
mat 14, and are able to be centered on foam mat 14 (if it is
desired). An increased sensing element size may increase the
sensitivity of sensor mat assembly 10.
[0034] Sensor mat assembly 10 is just one particular embodiment of
a sensor mat assembly of the present invention. In alternate
embodiments (discussed, for example, in reference to FIGS. 4 and
7), flat cable 20 may be positioned on the outside of foam mat 14,
rather than between layers of foam. Furthermore, flat cable 20 may
be positioned on a single side of foam mat 14 or may run along the
outer perimeter of foam mat 14.
[0035] FIG. 2 is an exploded perspective view of a first exemplary
embodiment of sensor mat assembly 22 in accordance with the present
invention. Sensor mat assembly 22 includes sensing element 24,
conductive patch 26, foam mat 28, and flat cable 30. Foam mat 28
may be secured to at least part of cable 30 using a suitable means,
such as an adhesive, thermal bonding, or a mechanical attachment.
Sensing element 24 and cable 30 may also be secured together using
an adhesive, or another suitable means, in order to increase the
rigidity of sensor mat assembly 90.
[0036] Conductive patch 26 is used to electrically connect
conductor 32 of flat cable 30 to sensing element 24. The inventive
means of electrically (and in some embodiments, physically)
connecting conductor 32 of flat cable 30 to conductive patch 26
will be discussed in detail below. Conductive patch 26 is formed of
a conductive material which may be conductive in either orthogonal
x-y-z coordinate directions (see coordinates shown in FIG. 2), or
in the z-coordinate direction. In general, conductive patch 26
should be large enough to provide relatively small flat cable 30
with a large area for potential contact.
[0037] Conductive patch 26 is preferably small enough so that it
does not contact an adjacent conductive patch (not shown in FIG. 2)
or sensing element (not shown in FIG. 2), which could interfere
with the ECU's ability to gather information from each sensing
element separately. For example, conductive patch 26 may be formed
so that it is no longer than sensing element 24 (i.e., conductive
patch 26 preferably has an x-coordinate dimension less than or
equal to the x-coordinate dimension of sensing element 24) and so
that it has a smaller width (i.e., a y-coordinate dimension) than
sensing element 24. As FIG. 2 shows, rather than having to connect
to sensing element 24 at exactly one particular point (e.g., when
using an eyelet and rivet connection means), conductive patch 26
provides a large range or area of possible connectivity points for
a conductor (e.g., first conductor 32) to contact, thus requiring
less precision in the assembly process of sensing element 24 and
cable 30.
[0038] Sensing element 24 may be electrically connected and secured
to conductive patch 26 using an adhesive. However, any suitable
connection and securing means may also be used. Sensing element 24
and conductive patch 26 may then be secured to foam mat 28 using a
pressure sensitive adhesive, or any other suitable securing means.
For example, conductive patch 26 may comprise two opposed adhesive
sides 26A and 26B, where adhesive side 26A adheres conductive patch
26 to sensing element 24 and adhesive side 26B adheres conductive
patch 26 to tab 42.
[0039] Flat cable 30 preferably has a small thickness (measured in
the z-coordinate direction) so that foam mat 28 does not protrude
in the z-coordinate direction where flat cable 30 is located. Such
a protrusion may cause discomfort to an occupant who is sitting on
a vehicle seat that incorporates sensor mat assembly 22. As seen in
exemplary FIG. 2, flat cable 30 is formed of first conductor 32,
second conductor 34, and third conductor 36, where conductors 32,
34, and 36 are aligned parallel in the y-coordinate direction and
separated from one another by insulating material 40. Preferably,
cable 30 also has an insulating material 41 (shown FIGS. 3A and 3B)
on opposing sides A and B to electrically insulate cable 30, but
such portions of insulating material 40 have been removed from FIG.
2 for clarity of illustration. Each conductor 32, 34, and 36
extends in a longitudinal direction (i.e., the x-coordinate
direction). Tabs 42, 44, and 46 are a part of each of the
conductors 32, 34, and 36, respectively. Each tab 42, 44, and 46
preferably connects to a separate sensing element, so that the ECU
is able to determine the impedance changes of each sensing element
in the sensor array of sensor mat assembly 22.
[0040] Tab 42 may be formed by first cutting conductor 32 in a
substantially lateral direction (i.e., in the y-coordinate
direction) to a desired width of tab 42, where the desired width is
preferably no wider than the width of conductor 32, but the width
may also include a part of insulating material 40 which is adjacent
either side of conductor 32. Next, cable 30 may be cut adjacent
conductor 32 along a substantially longitudinal direction (i.e., in
the x-coordinate direction) to a desired length of tab 42.
Specifically, part of insulation material 40 which is adjacent
opposing sides 32A and 32B of conductor 32 may be cut
longitudinally so that tab 42 includes insulation material 40, or
cable 30 may be cut longitudinally at sides 32A and 32B, where
insulation material 40 and conductor 32 contact one another, so
that tab 42 has little to no insulation material 40 (however, that
tab 42 may still have some insulation material 41, as shown in
FIGS. 3A and 3B). Preferably, at least some insulation material 40
remains between conductor 34 and conductor 32 and tab 42 so that
conductor 34 remains electrically insulated therefrom. Tab 42 may
be cut using any suitable cutting means, such as a mechanical
cutting means or a laser cutting means. Tab 42 is then bent
relative to cable 30 to project (or "protrude") outwardly
therefrom.
[0041] In the first exemplary embodiment, tab 42 is of sufficient
length to extend through opening 48 in foam mat 28 to physically
contact conductive patch 26. Tab 42 is bent so that contact surface
50 of tab 42 contacts conductive patch 26. At least contact surface
50 of tab 42, which is to contact conductive patch 26, is stripped
of its insulating layers 41 (shown in FIGS. 3A and 3B), such as by
using a laser, heat, mechanical abrasion, or any other suitable
means. However, all of tab 42 may also be stripped of its
insulating layer. It may be preferred to leave some insulating
material 41 on tab 42 because tab 42 may be more rigid. In
addition, it may be preferred to leave some insulating material 41
on tab 42 from a manufacturing aspect, because then less insulating
material 41 needs to be removed.
[0042] Tabs 44 and 46 may be formed in the same way as tab 42. Just
as tab 42 extends through opening 48 in foam mat 28, tab 44 may
extend through opening 52 in foam mat 28 to physically contact a
conductive patch (similar to conductive patch 26 and not shown in
FIG. 2), where the conductive patch is connected to a sensing
element (similar to sensing element 24 and not shown in FIG. 2).
Tab 44 may also be bent like tab 42 in order to provide a surface
to contact the conductive patch. Although a corresponding opening
is not shown for tab 46, tab 46 may also extend through foam mat 28
to contact a conductive patch. In alternate embodiments, tabs 42,
44, and 46 may be formed to be a different shape than that shown in
FIG. 2, for example, by not cutting conductor 32 and cable 30 in
substantially lateral and longitudinal directions.
[0043] Openings 48 and 52 are formed in foam mat 28 using any
suitable method, such as a laser cutting method. Openings 48 and 52
are wide enough to accommodate tabs 42 and 44, respectively. In
alternate embodiments, foam mat 28 may not have any openings
because tabs 42 and 44 may be rigid enough to move through foam mat
28 without the assistance of a precut opening. A substantially
liquid impervious, vapor permeable material may be placed over at
least a part of sensor mat assembly 22. The substantially liquid
impervious, vapor permeable material may be applied in more than
one piece to sensor mat assembly 22, where the seams are secured
using a suitable means, such as heat sealing the pieces together or
adhering the edge of the pieces together using an adhesive.
[0044] FIG. 3A is a partial schematic sectional view of sensor mat
assembly 22 of FIG. 2 as assembled and taken along line 3-3. Tab 42
of conductor 32 extends through opening 48 in foam mat 28 to
contact conductive patch 26, thereby creating an electrical
connection between conductor 32 and sensing element 24. Insulating
material 41 is shown to be on sides A and B (as shown in FIG. 2) of
cable 30.
[0045] Conductors 44 and 46 (shown in FIG. 2) of flat cable 30 are
not shown in FIG. 3 because from the side view, conductors 34 and
36 are behind conductor 32 (when viewing the image). Flat cable 30,
and therefore conductor 32, is connected to an ECU (not shown in
FIG. 3). Conductor 32 has a gap 56 where tab 42 was cut out. Gap 56
does not necessarily need to be completely through cable 30 because
a part of insulating layer 41 may be left in gap 56. Portion 58 of
conductor 32 and insulating layer 41 that is cut off from conductor
32 is essentially "dead wire" because it is no longer connected to
the ECU and in one embodiment, portion 58 may be removed from flat
cable 30 (as shown in FIG. 8).
[0046] FIG. 3B is a partial schematic sectional view of sensor mat
assembly 22 as assembled and taken along lines 3-3, where opening
48 has inclined sidewall 48B rather than a cylindrical shape as in
FIGS. 2 and 3A. Tab 43 is bent in an opposite direction than tab 42
of FIGS. 2 and 3A so that contact surface 51 extends to the right
of tab 43. At least one sidewall 48B of opening 48 is inclined
while sidewall 48A (and other sidewall portions) may run along the
z-coordinate (straight up and down) as shown. Tab 42 may then be
positioned along inclined sidewall 48B so that tab 42 extends
through foam mat 28 at an obtuse angle (where the angle is measured
between tab 42 and the part of cable 30 to which tab 42 is still
connected). When sensor mat assembly 22 is used in a vehicle, a
load (e.g., a person sitting on a vehicle seat) may be applied to
the top surface of sensing element 24. An inclined sidewall and tab
may help to distribute the pressure of the load better than with a
sidewall and tab that run straight up and down in the z-coordinate
direction. The inclined sidewall of opening 48 in FIG. 3B may also
be implemented into any sensor mat assembly of the present
invention, including the exemplary embodiments discussed below.
[0047] In alternate embodiments, sidewall 48A and other sidewall
portions may also be angled. If sidewall 48A is angled, tab 42 may
be positioned along sidewall 48A such that there is an acute angle
between tab 42 and the part of cable 30 to which tab 42 is still
connected. However, in that particular embodiment, there may be
more stress on tab 42 (particularly where conductor 32 is bent to
form tab 42, where tab 42 and the rest of conductor 32 meet) from
an applied load than with the exemplary embodiment including tab 42
positioned along sidewall 48B at an obtuse angle.
[0048] FIG. 4 is an exploded perspective view of a second exemplary
embodiment of sensor mat assembly 60 in accordance with the present
invention. Sensor mat assembly 60 includes sensing element 62
(similar to sensing element 24 of FIG. 2), conductive patch 64
(similar to conductive patch 26 of FIG. 2), flat cable 66 (similar
to flat cable 30 of FIG. 2), and foam mat 68 (similar to foam mat
28 of FIG. 2). Just as with the first exemplary embodiment, flat
cable 66 and sensing element 62 may be secured together using an
adhesive, or another suitable means, in order to increase the
rigidity of sensor mat assembly 60. Sensing element 62 is secured
to foam mat 68 using any suitable means, such as, for example, a
pressure sensitive adhesive. As with conductive patch 26,
conductive patch 64 is preferably small enough to not contact an
adjacent sensing element and/or conductive patch, and in this
exemplary embodiment, an adjacent tab of an adjacent conductor.
Rather than extending through foam mat 68 as in the first exemplary
embodiment, flat cable 66 is positioned on the same side of foam
mat 68 as sensing element 62 and conductive patch 64.
[0049] Tab 72 is formed from conductor 70 of flat cable 66 using a
method similar to that described in reference to tab 42 of FIG. 2.
Rather than projecting outwardly from conductor 70 (as tab 42
projects from conductor 32 in FIG. 2), tab 72 is folded in the
x-coordinate direction so that it is bent back over conductor 70.
Folding tab 72 in this way may create a spring-like force because
tab 72 may naturally want to move away from flat cable 66 and
towards gap 76. An exposed contact surface 74 on tab 72 is thus
aligned to contact (physically and electrically) conductive patch
64. The spring-like force of tab 72 applies an opposing force on
conductive patch 64. If conductive patch 64 and tab 72 are
connected using an adhesive, the spring-like action may help
reinforce the adhesion between tab 72 and conductive patch 64.
Conductive patch 64 is secured to sensing element 62 using an
adhesive, or other suitable means. In this way, conductor 70 (and
therefore, the ECU electrically connected to flat cable 66) is
electrically connected to sensing element 62.
[0050] FIG. 5 is a partial schematic sectional view of sensor mat
assembly 60 of FIG. 4 as assembled and taken along line 5-5.
Sensing element 62 and conductive patch 64 are secured to foam mat
68 using any suitable means, such as a pressure sensitive adhesive.
Contact surface 74 of tab 72 of conductor 70 contacts conductive
patch 64, thereby creating an electrical connection between
conductor 70 and sensing element 62. Flat cable 66 is secured to
conductive patch 64 using a pressure sensitive adhesive. Any other
suitable securing means may also be used. Flat cable 66, and
therefore conductor 72, is connected to an ECU (not shown in FIG.
3). Conductor 70 of flat cable 66 is positioned between insulating
layers 78. As with conductor 32 of FIG. 4, gap 76 in flat cable 66
indicates where tab 72 was formed. In an alternative embodiment,
portion 80 of conductor 70 and insulating layers 78 that have been
separated from tab 72 may be removed from flat cable 66 (as shown
in FIG. 8).
[0051] FIG. 6 is a bottom view of sensor mat assembly 60 as
assembled, where the view is that of the underside of sensing
element 62, conductive patch 64, cable 66, and foam mat 68 (where
the topside of each are shown in FIG. 4). Sensor array 84 now
includes six sensing elements, which are each electrically
connected to flat cable 66, but any suitable number of sensing
elements may be used. Gap 76 in flat cable 66 where tab 72 (shown
in FIGS. 4 and 5) was cut out of conductor 70 and insulating layers
78 can be seen. The stippled portion shown in gap 76 represents
conductive patch 64, which is positioned between flat cable 66 and
sensing element 62. The conductor in flat cable 66 which is
connected to each sensing element in sensor array 84 has a
corresponding gap where a tab was formed to electrically connect
that conductor of flat cable 66 to its respective sensing element.
As FIG. 6 shows, each sensing element in sensor array 84 connects
to a different conductor in flat cable 66 (e.g., conductor 70 is
connected to sensing element 62, conductor 70a is connected to
sensing element 62a, conductor 70b is connected to sensing element
62b, and so forth).
[0052] When sensor mat assembly 60 is later incorporated into a
vehicle seat, foam mat 68 may be folded along line 82, so that flat
cable 66 is positioned between two layers of foam mat 68 (e.g.,
sensor mat assembly 10 shown in FIG. 1). Alternately, sensor mat
assembly 60 may be folded the opposite way along line 82 so that
flat cable 66 is on the outside of foam mat 68 and runs along part
of the outer perimeter of foam mat 68. Sensor mat assembly 60 may
then be die cut using a laser or other suitable means to a desired
size and shape. A substantially liquid impervious, vapor permeable
material may then be placed over at least a part of sensor mat
assembly 60, as described in reference to sensor mat assembly
22.
[0053] FIG. 7 is an exploded perspective view of a third exemplary
embodiment of sensor mat assembly 90, which combines aspects of the
first and second exemplary embodiments. In FIG. 7, sensing elements
92, 94, 96 are positioned on opposing sides of foam mat 98, but
flat cable 100 is only on one side of foam mat 98. The embodiment
shown in FIG. 7 allows sensing elements 92, 94, 96 to be positioned
on opposing sides of foam mat 98 without having to wrap flat cable
100 around foam mat 98, which is allows less flat cable 100 to be
used in sensor mat assembly 90.
[0054] Sensing elements 92 and 96 are electrically connected to
flat cable 100 using aspects of the first exemplary embodiment.
Tabs 102 and 104 from conductors 114 and 116, respectively, of
cable 100 project through openings 106 and 108, respectively, in
foam mat 98 in order to contact conductive patches 110 and 112,
respectively. An electrical connection is then formed between
conductor 114 and sensing element 92, and a separate electrical
connection is formed between conductor 116 and sensing element 96.
Conductive patch 110 has adhesive on opposed sides 110A and 110B in
order to secure conductive patch 110 to sensing element 92 and tab
102, respectively. Similarly, conductive patch 112 has adhesive on
opposed sides 112A and 112B in order to secure conductive patch 112
to sensing element 96 and tab 104, respectively. Other suitable
securing means may also be used. Conductive patches 110 and 112 are
preferably small enough so as not to contact each another and so as
not to contact adjacent sensing elements 96 and 92, respectively.
Openings 106 and 108 are formed in foam mat 98 using a suitable
method, such as a laser cutting method. Again, openings 106 and 108
may not be necessary and tabs 102 and 104 may extend directly
through foam mat 98 rather than through precut openings 106 and
108.
[0055] Sensing element 94 is electrically connected to flat cable
100 using aspects of the second exemplary embodiment, since sensing
element 94 and conductive patch 118 are located on the same side of
foam mat 98 as cable 100. Thus, tab 120 does not need to project
through foam mat 98. Rather, tab 120 is bent backwards (in the
x-coordinate direction) in order to form a contact surface 124,
which contacts conductive patch 118, thereby creating an electrical
connection between conductor 122 and sensing element 94 (which is
electrically connected to conducive patch 118). Conductive patch
118 has adhesive on opposed sides 118A and 118B in order to
securably connect to sensing element 94 and contact surface 124 of
tab 120, respectively. Other suitable means of securing conductive
patch 118 to sensing element 94 and contact surface 124 of tab 120
may also be used. When tab 120 is folded onto conductor 122 as
shown in FIG. 7, it creates a spring-like action, where tab 120
applies an opposing force on conductive patch 118. This may help
form a secure connection between tab 120 and conductive patch
118.
[0056] Sensing elements 92, 94, and 96 may each be secured to flat
cable 100 using an adhesive, or another suitable means, in order to
increase the rigidity of sensor mat assembly 90. As with the
previous exemplary embodiments, a substantially liquid impervious,
vapor permeable material may be placed over at least a part of
sensor mat assembly 90.
[0057] As discussed earlier, that portion of a conductor of a cable
which is not connected to an electronic control unit and is
essentially "dead wire" may be removed after a tab is formed in the
conductor. The removal of such conductor portions results in a flat
cable 126 as shown in FIG. 8. Flat cable 126 is shown to have first
insulating layer 128 and second insulating layer 130 positioned on
opposing sides of flat cable 126. Positioned between first and
second insulating layers 128 and 130, respectively, are conductors
132, 134, 136, 138, and 140, which are separated by insulating
material 142, 144, 146, 148, 150, and 152. In this way, conductors
132, 134, 136, 138, and 140 are mutually insulated from one another
and from exterior contacts.
[0058] Tab 154 is formed in conductor 132. As discussed earlier,
tab 154 may be formed by first cutting conductor 132 in a
substantially lateral direction (i.e., in the y-coordinate
direction) to a desired width of tab 154, where the desired width
is preferably no wider than the width of conductor 132, but may
include a part of adjacent insulating material 142 and 144. A part
of cable 100 may be cut along the longitudinal direction (i.e., in
the x-coordinate direction) to a desired length of tab 154, such
that tab 154 is able to protrude from cable 100.
[0059] Tab 154 may then be used to electrically connect conductor
132 to a conductive patch (e.g., conductive patch 26 of FIG. 2),
which is electrically connected to a sensing element (e.g., sensing
element 24 of FIG. 2). In order to accomplish this, the portions of
tab 154 which will contact the conductive patch must be exposed
(i.e., insulating material must be removed). As FIG. 8 shows, the
portions of first and second insulating layer 128 and 130,
respectively, which contact tab 154 have been removed using a
laser, heat, mechanical abrasion, or any other suitable means. It
may not be necessary to remove both first and second insulating
layers 128 and 130, because only one side of tab 154 may be
contacting the conductive patch. Insulating material 142 and 144
has also been removed from tab 154, but it may not be necessary to
remove insulating material 142 and 144.
[0060] Rather than protruding (or "projecting") from conductor 132
(e.g., like tab 42 protrudes from conductor 32 in FIG. 2), tab 154
is at an end of conductor 132. The portion of conductor 132 to the
left of tab 156 (when viewing FIG. 8) is removed because it is
essentially "dead wire" since it is no longer connected to an
ECU.
[0061] Tabs 156, 158, 160, and 162 may be formed at the end of
conductors 134, 136, 138, and 140, respectively, using a similar
method as that used to form tab 154. The "dead wire" portions of
each conductor 134, 136, 138, and 140 are also removed. As a
result, each conductor 132, 134, 136, 138, and 140 has a different
length and the width of flat cable 126 becomes progressively
smaller as each conductor 134, 136, 138, and 140 is terminated by
connection to its respective sensing element. Preferably, each tab
154, 156, 158, 160, and 162 electrically and physically contacts a
separate conductive patch (and therefore, a separate sensing
element) so that an ECU (which is connected to flat cable 126) may
gather information from each sensing element separately. Forming
flat cable 126 as shown in FIG. 8 may be a more efficient use of
flat cable material than using a flat cable structure like flat
cable 30 of FIG. 2 because a single length of full-width flat cable
may be used to form two flat cables similar to flat cable 126.
[0062] With each of the three exemplary embodiments described
above, each sensor assembly (or sensor mat assembly) may be
incorporated into a vehicle seat assembly. Specifically, the sensor
assembly may be aligned in a recess of the vehicle seat assembly.
An outer covering (such as an aesthetic covering) may then be
fitted over at least part of the vehicle seat assembly, in which
the sensor assembly has been placed.
[0063] In addition to being included in a bottom seat portion of a
vehicle seat, a sensor assembly in accordance with the present
invention may be incorporated into other portions of the vehicle
seat. For example, the sensor assembly may be incorporated into a
back portion of a vehicle seat or into a side portion of a vehicle
seat in order to control the deployment of side air bags. A sensor
assembly of the present invention may also be used in any
application which may require the monitoring of the position,
orientation, presence, or size of a person or object within a
defined space.
[0064] The present invention also includes a method of forming the
inventive sensor assembly and inventive sensor mat assembly. The
sequence of the present invention's method steps is not limited to
the sequence recited in the claims, unless a previously recited
step is a prerequisite to completing a subsequent step. Rather, the
method steps recited in the claims may be completed in any suitable
order.
[0065] Although the present invention has been described with
reference to preferred embodiments, workers skilled in the art will
recognize that changes may be made in form and detail without
departing from the spirit and scope of the invention.
* * * * *