Information
-
Patent Grant
-
6626046
-
Patent Number
6,626,046
-
Date Filed
Wednesday, September 26, 200123 years ago
-
Date Issued
Tuesday, September 30, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Lefkowitz; Edward
- Ellington; Alandra N.
Agents
-
CPC
-
US Classifications
Field of Search
US
- 073 754
- 073 727
- 073 706
- 073 721
- 338 42
-
International Classifications
-
Abstract
It is the objective of this invention to reduce deviation in contact resistance variation between electrodes among pressure-sensitive resistor sensors. The sensor is composed of a pair of films. One film has a plurality of electrode portions extending in a certain direction and the other film has at least one electrode portion that is arranged in a transverse relation with a plural of the electrode portions on the other film. Contact points generated by applied pressure are limited to crossing points between the electrode portions of the pair of films. As a result, variation in contact resistance due to applied pressure shift becomes more constant. Thus, it is possible to reduce deviation of contact resistance between the electrodes among sensors.
Description
CROSS REFERENCE TO RELATED APPLICATION
This application is based on and incorporates herein by reference Japanese Patent Application No. 2000-329895 filed on October 30, 2000.
BACKGROUND OF THE INVENTION
The present invention relates to a pressure-sensitive resistor sensor for detecting pressure applied thereto.
Pressure-sensitive resistor sensors are proposed as shown in
FIGS. 19
,
20
A and
20
B. These types of sensors have a bottom side film
110
formed with a bottom side electrode
100
and a top side film
210
formed with a top side electrode
200
. The bottom side film
110
and the top side film
210
facing each other are spaced apart from each other by a predetermined distance by a spacer film
300
interposed between the bottom side film
110
and the top side film
210
. When pressure is applied to the top side film
210
, the central part of the top side film
210
is deformed downwardly as shown in
FIG. 3
so that the top side electrode
200
contacts the bottom side electrode
100
. As the applied pressure increases, the number of contact points and total contact area between the electrodes
100
and
200
increase, thereby changing a contact resistance between the electrodes
100
and
200
.
The electrodes
100
and
200
of a proposed pressure-sensitive resistor sensor are both shaped in a planar disk as shown in FIG.
19
. Alternatively, the electrodes
100
and
200
are shaped in comb teeth and a planar disk, respectively, as shown in
FIGS. 20A and 20B
. With this structure, the contact points between the electrodes
100
and
200
depend on the surface roughness of the electrodes
100
and
200
. It is therefore difficult to control the number of contact points and total contact area uniformly among sensors. As a result, sensor output characteristics vary from sensor to sensor.
SUMMARY OF THE INVENTION
It is an object of the present invention to reduce deviation in contact resistance variation between electrodes among pressure-sensitive resistor sensors.
According to the present invention, one of a pair of films has a plurality of electrode portions and the other of the pair has at least one electrode portion that crosses the plurality of electrode portions on the one of the pair. Contact points generated by applied pressure are limited to crossing points between the electrode portions of the pair of films. Thus, the number of contact points and total contact area increase uniformly among sensors as the applied pressure increases.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:
FIG. 1A
is a plan view showing a first embodiment of a pressure-sensitive resistor sensor of the present invention, and
FIG. 1B
is a cross-sectional view of an electrode portion of the first embodiment taken along line IB—IB in
FIG. 1A
;
FIGS. 2A and 2B
are cross-sectional views of the first embodiment taken along lines IIA—IIA and IIB—IIB in
FIG. 1A
, respectively;
FIG. 3
is a cross-sectional view showing operation of the first embodiment;
FIG. 4
is a plan view showing a seat sensor using the first embodiment;
FIG. 5
is a plan view showing a first modification of the first embodiment;
FIG. 6
is a plan view showing a second modification of the first embodiment;
FIG. 7A
is a plan view showing a second embodiment of a pressure-sensitive resistor sensor of the present invention, and
FIG. 7B
is a cross-sectional view of an electrode portion of the second embodiment taken along line VIIB—VIIB in
FIG. 7A
;
FIG. 8
is a plan view showing a first modification of the second embodiment;
FIG. 9
is a plan view showing a second modification of the second embodiment;
FIG. 10
is a plan view showing a third modification of the second embodiment;
FIG. 11
is a plan view showing a fourth modification of the second embodiment;
FIG. 12
is a plan view showing a fifth modification of the second embodiment;
FIG. 13A
is a plan view showing a sixth modification of the second embodiment, and
FIG. 13B
is a cross-sectional view of an electrode portion of the sixth modification of the second embodiment taken along line XIIIB—XIIIB in
FIG. 13A
;
FIG. 14
is a plan view showing a seventh modification of the second embodiment;
FIG. 15
is a plan view showing a third embodiment of a pressure-sensitive resistor sensor of the present invention;
FIGS. 16A and 16B
are cross-sectional views of the third embodiment taken along lines XVIA—XVIA and XVIB—XVIB in
FIG. 15
, respectively;
FIG. 17
is a plan view showing a fourth embodiment of a pressure-sensitive resistor sensor of the present invention;
FIGS. 18A and 18B
are cross-sectional views of the fourth embodiment taken along lines XVIIIA—XVIIIA and XVIIIB—XVIIIB in
FIG. 17
, respectively;
FIG. 19
is a cross-sectional view showing a pressure-sensitive resistor sensor according to a related art; and
FIG. 20A
is a plan view showing a pressure-sensitive resistor sensor according to another related art, and
FIG. 20B
is a cross-sectional view of the related art taken along line XXB—XXB in FIG.
20
A.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention will be described in detail with reference to various embodiments and modifications.
(First Embodiment)
A pressure-sensitive resistor sensor according to a first embodiment is shown in
FIGS. 1A
,
1
B to FIG.
6
and indicated with reference numeral
1
. A plurality of sensors
1
may be connected to each other and provided in a vehicle seat
2
as shown in
FIG. 4
to operate as a seat sensor that detects the size of a passenger (adult or child) on the seat
2
.
As shown in
FIGS. 2A and 2B
, each sensor
1
has a bottom side film
3
and a top side film
4
(for instance PEN films). The films
3
and
4
are attached to each other by an adhesive
6
with a spacer film
5
interposed between the films
3
and
4
to provide a predetermined clearance. The films
3
and
4
have bottom side and top side electrode layers, respectively, that face each other and are spaced apart from each other in the central part of the films
3
and
4
.
As shown in
FIG. 1A
, the bottom side electrode layer comprises a plurality of linear (straight) electrodes
7
and arc-shaped electric leads
8
that are connected to the electrodes
7
. The electrodes
7
comprise two positive side electrodes
7
A and two negative side electrodes
7
B that are both in a comb teeth shape. The number of positive side electrodes
7
A and negative side electrodes
7
B may be one, three or more. The electric leads
8
comprise positive side lead
8
A and negative side lead
8
B that face each other on the same circumference of a circle. The positive side electrodes
7
A and the negative side electrodes
7
B are aligned in parallel with each other with a predetermined clearance.
The electrodes
7
and the electric leads
8
are formed by means of forming base layers
7
a
and
8
a
on the bottom side film
3
and forming thereon resistive layers
7
b
and
8
b
. A method to form the base layers
7
a
and
8
a
is screen-printing with Ag paste onto the surface of the bottom side film
3
. A method to form the resistive layers
7
b
and
8
b
is screen-printing with a compound of conductive particles and resin or resistive resin on the top of the base layers
7
a
and
8
a
. As shown in
FIG. 1A
, The positive side lead
8
A and negative side lead
8
B are connected to each other with a resistive layer
9
comprising the resistive layer
8
b
(
7
b
) to provide a function to detect an open circuit. As shown in
FIG. 1B
, the cross-sectional structure of the electrodes
7
and
10
is a twin-peak-mountain shape in the case that both electrodes
7
and
10
are formed with screen-printing and the widths of the electrode
7
and
10
are 1.5 mm, respectively.
The top side electrode layer shown in
FIG. 1A
comprises three linear (straight) electrodes
10
. The electrodes
10
shown in FIG.
2
A and
FIG. 2B
comprise base layers
10
a
on the top side film
4
and resistive layers
10
b
on the top of the base layers
10
a
to provide the same line width, e.g., 1.5 mm, as that of the bottom side electrodes
7
. The base layer
10
a
and the resistive layer
10
b
are formed in the same way to form the bottom side electrode layer, i.e., a method to form the base layer
10
a
is screen-printing with Ag paste onto the surface of the top side film
4
. A method to form the resistive layer
10
b
is screen-printing with a compound of conductive particles and resin or resistive resin on the top of the base layer
10
a.
The electrodes
10
are aligned in parallel with each other in a predetermined clearance. Each end of the electrodes
10
is connected to other ends of adjacent electrodes in an arc shape to provide a closed circuit. The number of the electrodes
10
may be one, two, four or more. In modifications shown in FIG.
5
and
FIG. 6
, electrodes
10
have two and four electrodes, respectively. As shown in
FIG. 1A
, the bottom side and the top side electrode layers face each other in such way that each of the bottom side electrodes
7
A and
7
B is arranged in a transverse relation with the top side electrodes
10
.
The operation and the advantage of the pressure-sensitive resistor sensor
1
are described as follows. As shown in
FIG. 3
, the central part of the top side film
4
is distorted downward and the top side electrodes
10
contact the bottom side electrodes
7
when the top side film
4
is pressed by pressure P. As shown in
FIG. 1A
, contact points between the bottom side electrodes
7
and the top side electrodes
10
are limited to a plurality of crossing points
11
between the electrodes
7
and
10
.
Therefore, the number of contact points and total contact area in crossing points
11
increases as applied pressure increases. Applied pressure is measured by contact resistance shift due to changes in both the number of contact points and total contact area. In the case that this sensor structure is employed, contact points between the bottom side electrodes
7
and the top side electrodes
10
are limited to a plurality of crossing points
11
between the electrodes
7
and
10
so that variation in contact resistance due to applied pressure shift becomes more constant. As a result, it is possible to reduce deviation of contact resistance between the electrodes
7
and
10
among sensors and allow stable detection of applied pressure.
(Second Embodiment)
In this embodiment of pressure-sensitive resistor sensor
1
, each of the electrodes
7
and
10
have a different width from that in the first embodiment. In
FIGS. 7
to
12
, each of the electrodes
7
and
10
have 0.9 mm width. With this width, the cross-sectional structure of the electrodes
7
and
10
becomes a single-peak-mountain shape as shown in FIG.
7
B. In a modification shown in
FIG. 12
, the top side electrode layer has a plurality of circular electrodes
10
that are different from each other in diameter and arranged in a concentric shape. In this modification, contact points between the bottom side electrodes
7
and the top side electrodes
10
also are limited to a plurality of crossing points
11
between the electrodes
7
and
10
so that the same effect as that in the first embodiment is provided.
In a modification shown in
FIGS. 13A
,
13
B and
14
, at the positive side electrodes
7
A and the negative side electrodes
7
B of the bottom electrode layer, a common resistive layer
7
b
is formed to cover a plurality of base layer
7
a
in the case that the width of the electrodes
7
becomes narrower, e.g., 0.5 mm. With this width, the cross-sectional structure of the electrodes
7
A and
7
B becomes a quintuple-peak-mountain shape as shown in FIG.
13
B.
(Third Embodiment)
In a third embodiment of the pressure-sensitive resistor sensor shown in
FIGS. 15
,
16
A and
16
B, the base layer
10
a
of the top side electrodes
10
in both the first embodiment and the second embodiment is removed and the top side electrodes
10
comprise only the resistive layer
10
b
. In this embodiment, surface roughness of the top side electrodes
10
(the resistive layer
10
b
) is homogenized so that contact resistance with the bottom side electrodes
7
becomes more stable. As a result, the deviation of contact resistance between the electrodes
7
and the electrodes
10
among sensors can be more reduced.
(Fourth Embodiment)
In a fourth embodiment shown in
FIGS. 17
,
18
A and
18
B, both the base layer
10
a
of the top side electrodes
10
and the base layer
7
a
of the bottom side electrodes
7
in both the first embodiment and the second embodiment are removed and both the topside electrodes
10
and the bottom side electrodes
7
comprise only resistive layer
7
b
and
10
b
, respectively. In this embodiment, surface roughness of both the top side electrodes
10
(the resistive layer
10
b
) and the bottom side electrodes
7
(the resistive layer
7
b
) is homogenized so that contact resistance between both the electrodes
7
and
10
becomes furthermore stable. As a result, the deviation of contact resistance between the electrodes
7
and
10
among sensors can be furthermore reduced.
Claims
- 1. A pressure-sensitive resistor sensor comprising:a first film having a first electrode layer; and a second film having a second electrode layer, the second electrode layer being spaced apart from the first electrode layer by a predetermined distance and facing the first electrode layer, wherein the first electrode layer is formed with a plurality of first electrode portions including a plurality of positive side electrode portions arranged in parallel with each other in a comb-shaped configuration and a plurality of negative side electrode portions arranged in parallel with each other in a comb-shaped configuration, the positive side electrode portions and the negative side electrode portions being interleaved with one another with a predetermined clearance defined therebetween; the second electrode layer being formed with a plurality of concentrically arranged second electrode portions; each of the positive side electrode portions and each of the negative side electrode portions respectively cross over any one of the plurality of second electrode portions to form a plurality of crossing points; and the second electrode portions are arranged to electrically contact the positive side electrode portions and the negative side electrode portions upon application of pressure thereto to short the positive side electrode portions and negative side electrode portions.
- 2. The pressure-sensitive resistor sensor as in claim 1, wherein each of the first and second electrode portions comprises a single-peak electrode portion.
- 3. A pressure-sensitive resistor sensor comprising:a first film having a first electrode layer; and a second film having a second electrode layer spaced apart from the first electrode layer by a predetermined distance and facing the first electrode layer, wherein the first electrode layer is formed with first electrode portions each arranged in a first direction, and the second electrode layer is formed with second electrode portions arranged in a second direction transverse to the first direction of the first electrode portions, the first electrode portions each including a positive side base, a negative side base, a positive side electrode portion connected to the positive side base and a negative side electrode portion connected to the negative side base; and the second electrode portions being arranged to electrically contact the positive side electrode portion and the negative side electrode portion of the first electrode portions upon application of pressure thereto to short the positive side base and the negative side base.
- 4. The pressure-sensitive resistor sensor as in claim 3, wherein:the second electrode portions of the second electrode layer each include a base and a resistive part formed on the base.
- 5. The pressure-sensitive resistor sensor as in claim 3, wherein:the second electrode portion is of the second electrode layer each include a resistive part without a base.
- 6. The pressure-sensitive resistor sensor as in claim 3, wherein:one of the first electrode portions includes a base and a resistive part located on the base, wherein the base extends from the positive side base and the negative side base.
- 7. The pressure-sensitive resistor sensor as in claim 3, wherein:each of the first electrode portions of the first electrode layer includes a resistive part without a base.
- 8. The pressure-sensitive resistor sensor as in claim 3, wherein at least the first electrode portions comprise double-peak electrode portions.
- 9. The pressure-sensitive resistor sensor as in claim 3, wherein at least the first electrode portions comprise single-peak electrode portions.
- 10. The pressure-sensitive resistor sensor as in claim 3, wherein at least the first electrode portions comprise multiple-peak electrode portions.
- 11. A pressure-sensitive resistor sensor comprising:a first film having a first electrode layer formed with first electrode portions extending in a first direction; a second film having a second electrode layer spaced apart from the first electrode layer by a predetermined distance and facing the first electrode layer, wherein the first electrode layer is formed with a plurality of first electrode portions; the first electrode portions include a plurality of positive side electrode portions arranged in parallel with each other in a comb-shaped configuration and a plurality of negative side electrode portions arranged in parallel with each other in a comb-shaped configuration; the positive side electrode portions and the negative side electrode portions interleave with each other with a predetermined clearance therebetween; the second electrode layer is formed with a plurality of second electrode portions arranged in a second direction transverse to the first direction; each of the positive side electrode portions and each of the negative side electrode portions cross over any one of the second electrode portions at to form a plurality of crossing points; and the second electrode portions are arranged to electrically contact the positive side electrode portions and the negative side electrode portions upon application of pressure thereto to short the positive side electrode portions and negative side electrode portions.
- 12. The pressure-sensitive resistor sensor as in claim 11, wherein each of the first and second electrode portions comprises a double-peak electrode portion.
- 13. The pressure-sensitive resistor sensor as in claim 11, wherein each of the first and second electrode portions comprises a single-peak electrode portion.
- 14. The pressure-sensitive resistor sensor as in claim 11, wherein each of the first and second electrode portions comprises a multiple-peak electrode portion.
- 15. A pressure-sensitive resistor sensor comprising:a first film having a first electrode layer; and a second film having a second electrode layer spaced apart from the first electrode layer by a predetermined distance and facing the first electrode layer, wherein the first electrode layer is formed with first electrode portions each arranged in a direction, the second electrode layer is formed with a plurality of concentrically arranged electrode portions, each of the first electrode portions includes a positive side base, a negative side base, a positive side electrode portion connected to the positive side base, and a negative side electrode portion connected to the negative side base, and the second electrode portions are arranged to electrically contact the positive side electrode portion and the negative side electrode portion of the first electrode portions upon application of pressure thereto to short the positive side base and the negative side base.
- 16. The pressure-sensitive resistor sensor as in claim 2, wherein the single-peak electrode portion is formed by screen-printing such that a cross-sectional shape of the single-peak electrode portion has a single peak.
- 17. The pressure-sensitive resistor sensor as in claim 13, wherein the single-peak electrode portion is formed by screen-printing such that a cross-sectional shape of the single-peak electrode portion has a single peak.
- 18. A pressure-sensitive resistor sensor comprising:a first film having a first electrode layer formed with first electrode portions extending in a first direction; a second film having a second electrode layer spaced apart from the first electrode layer by a predetermined distance and facing the first electrode layer, wherein the second electrode layer is formed with second electrode portions arranged in a comb-shaped configuration in a second direction transverse to the first direction, each of the first electrode portions cross over each of the second electrode portions at a plurality of respective crossing points, and each of the first and second electrode portions comprises a double-peak electrode portion.
- 19. A pressure-sensitive resistor sensor comprising:a first film having a first electrode layer formed with first electrode portions extending in a first direction; a second film having a second electrode layer spaced apart from the first electrode layer by a predetermined distance and facing the first electrode layer, wherein the second electrode layer is formed with second electrode portions arranged in a comb-shaped configuration in a second direction transverse to the first direction, each of the first electrode portions cross over each of the second electrode portions at a plurality of respective crossing points, and each of the first and second electrode portions comprises a multiple-peak electrode portion.
Priority Claims (1)
| Number |
Date |
Country |
Kind |
| 2000-329895 |
Oct 2000 |
JP |
|
US Referenced Citations (6)
Foreign Referenced Citations (3)
| Number |
Date |
Country |
| A-60-35427 |
Feb 1985 |
JP |
| B2-2576571 |
Nov 1996 |
JP |
| A-2000-88670 |
Mar 2000 |
JP |
