US3943376A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Occupancy detector apparatus for automotive safety systems
Assignee: Fairchild Semiconductor Corp
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Filing: 1975-01-27
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Granted: 1976-03-09
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Expires: 1995-01-27
Abstract
Abstract Occupancy detector apparatus including a metallic electrode disposed to cooperate with the body of an automobile to form an occupant sensing capacitor, a reference capacitor, and an IC capacitance detecting and logic generating circuit. The IC includes a current source for continuously supplying charging current to the sensing capacitor and the reference capacitor, a first charge detecting circuit for detecting the charge on the sensing capacitor, a second charge detecting circuit for detecting the charge on the reference capacitor, and a comparator circuit for comparing the output signals developed by the first and second charge detecting circuits and for developing a logic output commensurate with the relationship between the capacitances of the sensing capacitor and the reference capacitor.
Inventors
- 👤 David K. Long
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:50
CPC Classifications
B; B60; B60R; B60R22/00; B60R22/48; B60R2022/4808; B60R2022/4816; B60R2022/4858
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
168 words
Occupant presence detecting means comprising: means forming an occupant sensing capacitor having a first capacitance in the presence of an occupant and a second capacitance in the absence of an occupant; means forming a reference capacitor having a capacitance independent of the presence or absence of an occupant; means for supplying charging current to said sensing capacitor and said reference capacitor; first, second and third terminals; charge detecting means responsive to a first signal applied to said first terminal and operative to simultaneously develop second signal at said second terminal which is commensurate with the capacitance of said occupant sensing capacitor and a third signal at said third terminal which is commensurate with the capacitance of said reference capacitor; and comparator means responsive to said second and third signals and operative to develop an output signal having a first state when the capacitances of said sensing capacitor and said reference capacitor have a first predetermined relationship, and a second state when said capacitors have a second predetermined relationship.
Claim 2
Dependent Claim
168 words
Occupant presence detecting means comprising: means forming an occupant sensing capacitor having a first capacitance in the presence of an occupant and a second capacitance in the absence of an occupant; means forming a reference capacitor having a capacitance independent of the presence or absence of an occupant; means for supplying charging current to said sensing capacitor and said reference capacitor; first, second and third terminals; charge detecting means responsive to a first signal applied to said first terminal and operative to simultaneously develop second signal at said second terminal which is commensurate with the capacitance of said occupant sensing capacitor and a third signal at said third terminal which is commensurate with the capacitance of said reference capacitor; and comparator means responsive to said second and third signals and operative to develop an output signal having a first state when the capacitances of said sensing capacitor and said reference capacitor have a first predetermined relationship, and a second state when said capacitors have a second predetermined relationship.
Claim 3
Dependent Claim
75 words
Occupant presence detecting means as recited in claim 1 wherein said charge detecting means includes a first transistor having a first electrode coupled to said occupant sensing capacitor, a second electrode coupled to said first terminal and a third electrode coupled to said second terminal, and a second transistor having a fourth electrode coupled to said reference capacitor, a fifth electrode coupled to said first terminal and a sixth electrode coupled to said third terminal.
Claim 4
Dependent Claim
59 words
Occupant presence detecting means as recited in claim 2 wherein said charge detecting means further includes a first impedance means coupled between said second terminal and circuit ground, and a second impedance means coupled between said third terminal and circuit ground, and biasing means for continuously causing biasing current to flow through and said first and second impedance means.
Claim 5
Dependent Claim
44 words
Occupant presence detecting means as rated in claim 7 wherein said occupant sensing capacitor includes a metallic electrode positioned so as to be separated from a ground plane by a volume of space in which the presence of an occupant is to be detected.
Claim 6
Dependent Claim
31 words
Occupant presence detecting means as recited in claim 4 wherein said metallic electrode and said reference capacitor are coupled to said charge detecting means by electrical conductors of substantially equal length.
References Cited (Backward Citations)
US3751674A
Cited
US3864668A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-03-09 | 1979-09-08 | 1980-03-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-03-09 | 1983-09-08 | 1984-03-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-03-09 | 1987-09-08 | 1988-03-09 | $7700.00 | Window Closed / Lapsed |