Patent US5809019A successfully refreshed from Google Patents.
US4001802A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Solid state thermistor switch
Assignee: Motors Liquidation Co
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Filing: 1975-08-04
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Granted: 1977-01-04
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Expires: 1995-08-04
Abstract
Abstract A switch includes a self-heating thermistor which has a certain resistance value when exposed to a medium of low thermal conductivity and a thermally conductive solid for movement into contact with the thermistor to lower its temperature and change its resistance. The solid is moved relative to the thermistor in response to any mechanical movement such as a float responding to liquid level or the closure of a door.
Inventors
- 👤 Douglas I. Fales
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 16:14
CPC Classifications
G; G01; G01F; G01F23/00; G01F23/30; G01F23/56; G01F23/60; G01F23/22; G01F23/24; G01F23/246; G01F23/247; G01F23/64; G01F23/68; G01F23/70; H; H03; H03K; H03K17/00; H03K17/94
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
150 words
A condition responsive switch coupled with a current supply comprising a thermistor means connected to the current supply to develop a relatively high temperature and one resistance value when exposed to a medium of low thermal conductivity and a lower temperature and a substantially different resistance value when exposed to a medium of relatively high thermal conductivity, a solid state medium of high thermal conductivity having a first position in thermal contact with the thermistor means to effect cooling thereof and a second position out of thermal contact with the thermistor means to allow heating thereof, means responsive to a condition for moving the solid state medium between said first position and said second position, and, means responsive to the resistance value of the thermistor means to thereby indicate whether the solid state medium is in said first position or said second position thereby providing an indication of the condition.
Claim 2
Dependent Claim
150 words
A condition responsive switch coupled with a current supply comprising a thermistor means connected to the current supply to develop a relatively high temperature and one resistance value when exposed to a medium of low thermal conductivity and a lower temperature and a substantially different resistance value when exposed to a medium of relatively high thermal conductivity, a solid state medium of high thermal conductivity having a first position in thermal contact with the thermistor means to effect cooling thereof and a second position out of thermal contact with the thermistor means to allow heating thereof, means responsive to a condition for moving the solid state medium between said first position and said second position, and, means responsive to the resistance value of the thermistor means to thereby indicate whether the solid state medium is in said first position or said second position thereby providing an indication of the condition.
Claim 3
Dependent Claim
145 words
A liquid level switch coupled with a current supply comprising a thermistor means connected to the current supply to develop a relatively high temperature and one resistance value when exposed to a medium of low thermal conductivity and a lower temperature and a substantially different resistance value when exposed to a medium of relatively high thermal conductivity, a float in the liquid assuming a position according to the liquid level, a metallic member of high thermal conductivity selectively moved by the float according to changes of the liquid level into thermal contact with the thermistor means to effect cooling thereof and out of thermal contact with the thermistor means to allow heating thereof, and means responsive to the resistance value of the thermistor means to indicate whether the metallic member is in contact with the thermistor means thereby providing an indication of the liquid level.
Claim 4
Dependent Claim
145 words
A liquid level switch coupled with a current supply comprising a thermistor means connected to the current supply to develop a relatively high temperature and one resistance value when exposed to a medium of low thermal conductivity and a lower temperature and a substantially different resistance value when exposed to a medium of relatively high thermal conductivity, a float in the liquid assuming a position according to the liquid level, a metallic member of high thermal conductivity selectively moved by the float according to changes of the liquid level into thermal contact with the thermistor means to effect cooling thereof and out of thermal contact with the thermistor means to allow heating thereof, and means responsive to the resistance value of the thermistor means to indicate whether the metallic member is in contact with the thermistor means thereby providing an indication of the liquid level.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-01-04 | 1980-07-05 | 1981-01-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-01-04 | 1984-07-05 | 1985-01-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-01-04 | 1988-07-05 | 1989-01-04 | $7700.00 | Window Closed / Lapsed |