US4520885A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Load sensing apparatus with capacitive and inductive sensors
Assignee: JF FOORD (HOLDINGS) Ltd A CORP OF GREAT BRITAIN
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Filing: 1982-08-05
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Granted: 1985-06-04
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Expires: 2002-08-05
Abstract
Abstract A load-sensing mat comprising a pair of superposed spaced capacitance plates held together in a mat by resilient material. The load-sensing mat also contains a conductive loop for inductance dependent load detection.
Inventors
- 👤 Peter Jeffrey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 18:12
CPC Classifications
G; G01; G01G; G01G3/00; G01G3/12
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
92 words
A load-sensing mat comprising: (a) at least one pair of superposed spaced, substantially planar conductive elements embeded in the mat by a flexible resilient material, said pair of conductive elements constituting capacitance plates operative to produce an electric signal in response to the spacing between said capacitance plates when the mat is loaded to compress said resilient material; and (b) a conductive loop embeded in the mat by said flexible resilient material for providing an inductance-dependent indication of the presence of a load, said conductive loop being disposed around said capacitance plates.
Claim 2
Dependent Claim
92 words
A load-sensing mat comprising: (a) at least one pair of superposed spaced, substantially planar conductive elements embeded in the mat by a flexible resilient material, said pair of conductive elements constituting capacitance plates operative to produce an electric signal in response to the spacing between said capacitance plates when the mat is loaded to compress said resilient material; and (b) a conductive loop embeded in the mat by said flexible resilient material for providing an inductance-dependent indication of the presence of a load, said conductive loop being disposed around said capacitance plates.
Claim 3
Dependent Claim
26 words
A load-sensing mat according to claim 1 said capacitance plates and said conductive loop being disposed in a lower half of the thickness of the mat.
Claim 4
Dependent Claim
19 words
A load-sensing mat according to claim 1, said capacitance plates and said conductive loop being embeded at different levels.
Claim 5
Dependent Claim
30 words
A load-sensing mat according to claim 1, two said pairs of said capacitance plates being disposed inside said conductive loop in spaced apart relation across the width of the mat.
Claim 6
Dependent Claim
16 words
A load-sensing mat according to claim 4, said two pairs of capacitance plates having different widths.
Claim 7
Dependent Claim
21 words
A load-sensing mat according to claim 1, said resilient material being impregnated at and near its upper surface with anti-skid material.
Claim 8
Dependent Claim
14 words
A load-sensing mat according to claim 6, said anti-skid material comprising a fine aggregate.
Claim 9
Dependent Claim
45 words
A load-sensing mat according to claim 1, said resilient material comprising natural rubber latex and having an intermediate portion disposed between said capacitance plates, said intermediate portion being filled therein conductive fillers of carbon-black and a non-conductive plastic mesh penetrated by said natural rubber latex.
Claim 10
Dependent Claim
25 words
A load-sensing mat according to claim 8, wherein the resilient material immediately adjacent to and bonding the capacitance plates is of reduced conductive filler content.
Claim 11
Dependent Claim
18 words
A load-sensing mat according to claim 8, said intermediate portion including 5% to 25% by weight carbon-black content.
Claim 12
Dependent Claim
26 words
A load-sensing mat according to claim 8, said plastic mesh having a strand diameter of 0.3 to 0.5 mm and apertures of 3 to 4 mm.
Claim 13
Dependent Claim
33 words
A load-sensing mat according to claim 8, said resilient material further having an upper portion disposed above an upper one of said pair of capacitance plates, said upper portion being substantially electrically non-conductive.
Claim 14
Dependent Claim
17 words
A load-sensing mat according to claim 12, wherein the encapsulating resilient material has an electrically inert filler.
Claim 15
Dependent Claim
13 words
A load-sensing mat according to claim 13, wherein the inert filler is clay.
Claim 16
Dependent Claim
20 words
A load-sensing mat according to claim 14 with claim 2, wherein the clay is present in about 40% by weight.
Claim 17
Dependent Claim
24 words
A load-sensing mat according to claim 1, wherein the capacitance plates comprise apertured or expanded metal penetrated by the resilient material for bonding purposes.
Claim 18
Dependent Claim
14 words
A load-sensing mat according to claim 16, wherein the capacitance plates comprise metal mesh.
Claim 19
Dependent Claim
15 words
A load-sensing mat according to claim 10, wherein the metal mesh is of woven construction.
Claim 20
Dependent Claim
13 words
A load-sensing mat according to claim 8, wherein the metal is stainless steel.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-06-03 | 1988-12-03 | 1989-06-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-06-03 | 1992-12-03 | 1993-06-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-06-03 | 1996-12-03 | 1997-06-04 | $7700.00 | Window Closed / Lapsed |