U.S. patent application number 09/813336 was filed with the patent office on 2001-08-09 for strain gage with integral amplifier.
Invention is credited to Blakesley, Patrick B., Newcomer, James M., Nonnenmacher, Ronald C..
Application Number | 20010011481 09/813336 |
Document ID | / |
Family ID | 23478537 |
Filed Date | 2001-08-09 |
United States Patent
Application |
20010011481 |
Kind Code |
A1 |
Nonnenmacher, Ronald C. ; et
al. |
August 9, 2001 |
Strain gage with integral amplifier
Abstract
A weight sensor for measuring a weight applied to the sensor.
The sensor includes a substrate that has a center section that is
adapted to flex in response to the applied weight and a step
section that is attached to the center section. The step section
concentrates the weight onto to the center section. Strain gage
resistors are mounted on the center section of the substrate for
generating an electrical signal in response to the substrate being
flexed. A wing section is attached to the center section. The wing
section is out of the weight path and does not flex. The wing
section contains signal conditioning electronics operative to
condition the electrical signal.
Inventors: |
Nonnenmacher, Ronald C.;
(Elkhart, IN) ; Blakesley, Patrick B.; (Goshen,
IN) ; Newcomer, James M.; (Elkhart, IN) |
Correspondence
Address: |
Mark P. Bourgeois
CTS Corporation
905 West Boulevard North
Elkhart
IN
46514
US
|
Family ID: |
23478537 |
Appl. No.: |
09/813336 |
Filed: |
March 20, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09813336 |
Mar 20, 2001 |
|
|
|
09374874 |
Aug 16, 1999 |
|
|
|
6244116 |
|
|
|
|
Current U.S.
Class: |
73/862.044 |
Current CPC
Class: |
B60N 2/002 20130101;
G01G 19/4142 20130101; B60N 2/7094 20130101; G01G 3/1402
20130101 |
Class at
Publication: |
73/862.044 |
International
Class: |
G01L 001/22 |
Claims
What is claimed is:
1. A weight sensor for measuring a weight applied to the sensor,
comprising: a) a substrate including: 1) a center section that is
adapted to flex in response to the applied weight; 2) at least one
step section attached to the center section, the center section
located adjacent the step section, the step section adapted to
concentrate the weight applied thereon onto to the center section;
and 3) at least one outer section attached to the step section; b)
at least one strain gage resistor, mounted on the center section of
the substrate, for generating an electrical signal in response to
the substrate being stressed; and c) at least one wing section
attached to the center section, the wing section adapted to be out
of the path of the weight and not to flex, the wing section
containing signal conditioning electronics operative to condition
the electrical signal.
2. The weight sensor according to claim 1, wherein at least one
circuit line electrically connects the strain gage resistor to the
signal conditioning electronics.
3. The weight sensor according to claim 1, wherein the wing section
is connected to the center section by a bridge.
4. The weight sensor according to claim 1, wherein a wiring harness
is electrically connected to the signal conditioning
electronics.
5. The weight sensor according to claim 1, wherein the signal
conditioning electronics converts the electrical signal to a
digital electrical signal.
6. The weight sensor according to claim 5, wherein the signal
conditioning electronics includes at least one amplifier and an
analog to digital converter.
7. The weight sensor according to claim 5, wherein the outer
section has an aperture passing therethrough.
8. A weight sensor for measuring a weight applied to the sensor,
comprising: a) a gull wing shaped substrate having a center section
that is adapted to flex in response to the applied weight and a
pair of outer sections attached to the center section; b) at least
one strain gage resistor, mounted on the center section of the
substrate, for generating an electrical signal in response to the
substrate being stressed; and c) at least one wing section attached
to the center section, the wing section adapted to be out of the
path of the weight and not to flex, the wing section containing
signal conditioning electronics operative to condition the
electrical signal.
9. The weight sensor according to claim 8, wherein a step section
is attached between the center section and the outer sections, the
step sections adapted to concentrate the weight applied thereon
onto to the center section.
10. The weight sensor according to claim 9, wherein at least one
circuit line electrically connects the strain gage resistor to the
signal conditioning electronics.
11. The weight sensor according to claim 8, wherein the wing
section is connected to the center section by a bridge.
12. The weight sensor according to claim 8, wherein a wiring
harness is electrically connected to the signal conditioning
electronics.
13. The weight sensor according to claim 8, wherein the signal
conditioning electronics converts the electrical signal to a
digital electrical signal.
14. The weight sensor according to claim 8, wherein the signal
conditioning electronics includes at least one amplifier and an
analog to digital converter.
15. The weight sensor according to claim 8, wherein the outer
section has an aperture passing therethrough.
Description
CROSS REFERENCE TO RELATED AND CO-PENDING APPLICATIONS
[0001] This application is a continuation in part of U.S. patent
application Ser. No. 09/374,874, filed Aug. 16, 1999 and titled,
"Automobile seat weight Sensor".
[0002] This application is related to the following U.S. patent
applications: U.S. patent application Ser. No. 09/374,870, filed
Aug. 16, 1999 and titled, "Vehicle Occupant Position Detector and
Airbag Control System".
[0003] U.S. Pat. No. 6,161,891 issued Dec. 19, 2000 and titled,
"Vehicle Seat Weight Sensor".
[0004] The foregoing patents have the same assignee as the instant
application and are herein incorporated by reference in their
entirety for related and supportive teachings.
BACKGROUND OF THE INVENTION
[0005] 1. Field of the Invention
[0006] This invention relates to an automobile weight sensor for
detecting the presence of a person having a weight in a car seat,
and in particular to a sensor that can detect the presence of an
occupant using strain sensitive resistors and provide an electrical
signal to control activation of an airbag.
[0007] 2. Description of the Related Art
[0008] Various devices are well known for their ability to measure
force, pressure, acceleration, temperature, position, etc. by using
a sensing structure combined with signal processing electronics.
One general type of sensor or transducer for such applications is a
resistive strain gauge sensor in which force or pressure is sensed
or measured based on strain placed on the resistors. Resistive
strain gauges function by exhibiting changes in resistance
proportional to force which causes dimensional changes of the
resistor. An electrical signal changes voltage level as the
resistance changes.
[0009] Many types of strain gauge sensors have been designed and
made commercially available. Various strain gauge sensors have
proven to be generally satisfactory. Prior art sensors, however,
have tended to be rather expensive and not suitable in certain
applications such as sensing the presence of an occupant in an
automobile seat. A sensor suitable for such an application must be
compact, robust, impervious to shock and vibration and yet
inexpensive.
[0010] Automobile seats can use sensors to activate air bags, which
would be deployed during an accident. Injury to infants or small
children from air bag deployment with excessive force is a current
industry problem. A weight sensor in the seat can be used to
control the deployment force during air bag activation. If a heavy
person is in the seat, the airbag is deployed at full force. If a
light person is in the seat, such as a child, the airbag is
deployed at a slower, less forceful rate or not at all.
[0011] The generated electrical signal does not vary greatly with
the weight. As a result the typical electrical signal to be sensed
is in the order of millilvolts. When this electrical signal is
connected by a wiring harness to an airbag controller, it is
sussepetible to noise from cross-talk and coupled electromagnetic
interference. This noise can result in an inaccurate weight
reading.
[0012] A current unmet need exists for a reliable, low cost, simple
and robust automobile seat weight sensor that is not affected by
noise from cross-talk and coupled electromagnetic interference.
[0013] 3. Related Art
[0014] Examples of patents that are related to the present
invention are as follows, and each patent is herein incorporated by
reference for the supporting teachings:
[0015] U.S. Pat. No. 5,573,269 is an apparatus for sensing and
restraining an occupant of a vehicle seat.
[0016] U.S. Pat. No. 4,556,598 is a porcelain tape for producing
porcelainized metal substrates.
SUMMARY OF THE INVENTION
[0017] It is a feature of the invention to provide a reliable and
cost-effective weight sensor and strain gage for detecting
weight.
[0018] An additional feature of the invention is to provide a
weight sensor for measuring a weight applied to the sensor. The
sensor includes a substrate having a center section that is adapted
to flex in response to the applied weight, at least one step
section that is attached to the center section, the center section
located adjacent the step section, the step section adapted to
concentrate the weight applied thereon onto to the center section
and at least one outer section that is attached to the step
section. At least one strain gage resistor is mounted on the center
section of the substrate for generating an electrical signal in
response to the substrate being stressed. At least one wing section
is attached to the center section. The wing section is adapted to
be out of the path of the weight and not to flex. The wing section
contains signal conditioning electronics operative to condition the
electrical signal.
[0019] The invention resides not in any one of these features per
se, but rather in the particular combination of all of them herein
disclosed and claimed and it is distinguished from the prior art in
this particular combination of all of its structures for the
functions specified. Other features of the present invention will
become more clear from the following detailed description of the
invention, taken in conjunction with the accompanying drawings and
claims, or may be learned by the practice of the invention.
[0020] There has thus been outlined, rather broadly, the more
important features of the invention in order that the detailed
description thereof that follows may be better understood, and in
order that the present contribution to the art may be better
appreciated. There are, of course, additional features of the
invention that will be described hereinafter and which will form
the subject matter of the claims appended hereto. Those skilled in
the art will appreciate that the conception, upon which this
disclosure is based, may readily be utilized as a basis for the
designing of other structures, methods and systems for carrying out
the several purposes of the present invention. It is important,
therefore, that the claims be regarded as including such equivalent
constructions insofar as they do not depart from the spirit and
scope of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a perspective view of the preferred embodiment of
a strain gage having an integral amplifier.
[0022] FIG. 2 is a perspective view of an alternative embodiment of
a strain gage having an integral amplifier.
[0023] It is noted that the drawings of the invention are not to
scale. The drawings are intended to depict only typical embodiments
of the invention, and therefore should not be considered as
limiting the scope of the invention. The invention will be
described with additional specificity and detail through the use of
the accompanying drawings. In the drawings like numbering
represents like elements between the drawings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] Referring to FIG. 1, a strain gage or sensor with integral
amplifier 10 is shown. Sensor 10 has a metal substrate 12 with an
upper surface 12A and a bottom surface 12B. Metal substrate 12 is
preferably formed from steel. Substrate 12 has step sections 16
that extends downwardly generally perpendicularly on both sides of
a center section 14. A pair of outer flat sections 18 connect with
and extend away from step sections 16. Apertures 20 are located in
outer sections 18. Fasteners (not shown) would be used to attach
strain gage 10 to a structure that supports a weight or force to be
measured. The step sections concentrate the force of the weight to
be measured onto the center section causing the center section to
slightly flex.
[0025] A pair of wing sections 22 are attached by bridges 24 to
center section 14. The wing sections 22 are also formed from steel
and are preferably stamped at the same time as the rest of
substrate 12. The wing sections 22 are located out of the strain or
flexing path that affects center section 14. The weight applied to
strain gage 10 does not cause the wing sections to flex or have
strain therein.
[0026] Several strain gauge resistors 30 are arranged on surface
12A in center section 14. Details of the manufacture and operation
of resistors 30 are contained in the parent application U.S. patent
application Ser. No. 09/374,874, filed Aug. 16, 1999 and titled,
"Automobile seat weight Sensor", which is herein incorporated by
reference. Resistors 30 are strain sensitive and will change
resistance based on the amount of strain in center section 14. A
voltage source (not shown) applies a voltage source to resistors
30. The voltage level across the resistors changes in proportion to
the applied strain and produces an electrical output signal.
Resistors 30 are connected to an electronic signal processing
component 34 by a circuit line 32. Signal processing component can
include amplifiers to amplify the signal and filters to filter the
signal and an analog to digital converter to convert the signal to
a digital signal. In a typical configuration, Resistors 30 are
connected to form a full bridge circuit (not shown) that is well
known in the art.
[0027] Another circuit line 32 connects to electronic component 34
and to an output pad 36. The output pads 36 are used to solder to
individual wires in a wiring harness 38. Wiring harness 38 would
typically connect with an airbag controller through a connector
(not shown).
[0028] Resistors 30 can also be formed from a ceramic green tape.
Such methods of forming resistors on metal substrates are detailed
in U.S. Pat. No. 4,556,598 titled, "A porcelain tape for producing
porcelainized metal substrates", the contents of which are
specifically herein incorporated by reference.
[0029] Prior art strain gages produce an output voltage in the
millivolt range. With the present invention, strain gage with
integral amplifier 10 of the present invention can produce an
output signal of several volts. This makes the strain gage more
compatible with low cost computer systems such as those used in
automotive applications. The dimensions of the substrate can be
varied to sense various weight ranges. For example, one design
could have a full scale load of 10 pounds while another design
might have a full scale load of 400 pounds.
[0030] Electronic component 34 amplifies the electrical signal.
Electronic component 34 can be a OPA-2241 available from Texas
Instruments of Dallas, Tex. Various amplifier type circuits can be
used. The electronic components are located on the wing 22 which is
formed on the same substrate 12 as the strain gage, but is in an
area of very low to zero stress. The reduced stress promotes long
component life for the electronic components by not subjecting the
solder joints to excess mechanical stress. Having the electronics
directly adjacent the strain gage resistors 30 provides a
physically short signal path from the strain gage to the signal
processing electronics. This reduces the overall size of the sensor
and makes the sensor less susceptible to interference from
noise.
[0031] The use of bridge 24 to mount wing 22 significantly reduces
stress on the electronics components from the applied load and
carries conductor traces to connect the electronics to the
resistors.
[0032] Referring to FIG. 2, an alternative embodiment of a strain
gage or sensor with integral amplifier 50 is shown. Sensor 50 is
similar to sensor 10 of FIG. 1 except that the step sections have
been eliminated. In sensor 50 the center section 14 is connected
directly to the outer flat sections 18.
[0033] While the invention has been taught with specific reference
to these embodiments, someone skilled in the art will recognize
that changes can be made in form and detail without departing from
the spirit and the scope of the invention. The invention should
therefore be limited only by the scope of the human imagination.
The described embodiments are to be considered in all respects only
as illustrative and not restrictive. The scope of the invention is,
therefore, indicated by the appended claims rather than by the
foregoing description. All changes which come within the meaning
and range of equivalency of the claims are to be embraced within
their scope.
* * * * *