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Patent US3581204A successfully refreshed from Google Patents.
US3581204A
Expired / Lapsed
US
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Electromechanical recorder automatic zero apparatus
Assignee: Dow Chemical Co
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Filing: 1969-04-14
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Granted: 1971-05-25
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Expires: 1989-04-14
Abstract
Abstract This invention relates to means for providing an automatic zero to correct periodically for instrument drift to precisely the same point each time after such drift occurred. The automatic zero means of this invention senses the position of a recorder pen and corrects the incoming signal to move the pen to a definite position. Variations that may be encountered in an electronic zero or signal condition feeding the recorder are zeroed out with the signal drift in order to position the recorder pen at a specified point.
Inventors
- 👤 Fred D Martin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 06:35
CPC Classifications
G; G01; G01R; G01R17/00; G05; G05D; G05D3/00; G05D3/12; G05D3/14
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
175 words
Electromechanical recorder zeroing apparatus for correcting recorder pen position to compensate for instrument drift, comprising a recorder having inputs, a pen whose position is coupled to a movable contact on a slide wire resistance element, said slide wire resistance element having a constant potential applied across it, a source of reference zeroing potential, a differential amplifier having a pair of inputs and an output, said reference zeroing potential being coupled to one input of said differential amplifier, switching means for coupling said movable contact to the other input of said differential amplifier at predetermined intervals, a storage capacitor, said storage capacitor being coupled between the output and the input of said differential amplifier to which said movable contact is coupled at predetermined intervals, a signal generating element having output terminals one of which is at ground potential, a zero correction signal resistance element connected between the output of the differential amplifier and ground potential, said signal generating element and said zero correction signal resistance element being connected in series across the inputs of said recorder.
Claim 2
Dependent Claim
175 words
Electromechanical recorder zeroing apparatus for correcting recorder pen position to compensate for instrument drift, comprising a recorder having inputs, a pen whose position is coupled to a movable contact on a slide wire resistance element, said slide wire resistance element having a constant potential applied across it, a source of reference zeroing potential, a differential amplifier having a pair of inputs and an output, said reference zeroing potential being coupled to one input of said differential amplifier, switching means for coupling said movable contact to the other input of said differential amplifier at predetermined intervals, a storage capacitor, said storage capacitor being coupled between the output and the input of said differential amplifier to which said movable contact is coupled at predetermined intervals, a signal generating element having output terminals one of which is at ground potential, a zero correction signal resistance element connected between the output of the differential amplifier and ground potential, said signal generating element and said zero correction signal resistance element being connected in series across the inputs of said recorder.
Claim 3
Dependent Claim
19 words
Apparatus in accordance with claim 1, wherein said slide wire resistance element is an integral part of said recorder.
Claim 4
Dependent Claim
18 words
Apparatus in accordance with claim 1, wherein said signal generating element is a bridge type thermal conductivity detector.
Claim 5
Dependent Claim
28 words
Apparatus in accordance with claim 1, wherein a power source is coupled to said differential amplifier, to said slide wire resistance element and said source of zeroing potential.
Claim 6
Dependent Claim
26 words
Apparatus in accordance with claim 1, wherein said source of zeroing potential is a voltage developed across a resistor in series with a signal generating element.
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) | 1974-05-24 | 1974-11-23 | 1975-05-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-24 | 1978-11-23 | 1979-05-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-24 | 1982-11-23 | 1983-05-25 | $7700.00 | Window Closed / Lapsed |