US5278513A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Continuous condition sensing system
Assignee: Drexelbrook Controls Inc
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Filing: 1991-08-22
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Granted: 1994-01-11
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Expires: 2011-08-22
Abstract
Abstract A probe developing an admittance with a material whose condition is to be continuously measured is capacitively coupled with a variable frequency oscillator, preferably one having a digital output stage, for generating a variable frequency signal having a period varying with the admittance developed at the probe. Both the oscillator input and output are capacitively coupled to the probe. In a preferred embodiment, a set point circuit including a plurality of resistors coupled in parallel with the oscillator output and a plurality of switches coupled in parallel with the probe conductor and each with a different one of the resistor, provides easy circuit adjustment for use of the system with a variety of materials. A preferred digital circuit employing a pair of flip flops, fixed timer and one shot generate a fixed period variable duration duty cycle digital voltage level signal for transmission, if desired, or for conversion into a variable current signal.
Inventors
- 👤 L. Jonathan Kramer
- 👤 Steven R. Petersen
- 👤 Herbert A. Shauger, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 01:18
CPC Classifications
G; G01; G01R; G01R27/00; G01R27/02; G01R27/26; G01R27/2605
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
203 words
Method for monitoring the condition of a material comprising: a) providing a plurality of different component values and a switch for selecting at least one of the component values; b) providing a first signal having a magnitude indicative of the condition of the material, the magnitude of the first signal varying with variations in the condition; c) converting the first signal to a second signal having a period that varies with variations in the magnitude of the first signal, a range of periods of the second signal being determined by a selected component value; d) selecting one of the component values via the switch depending upon an expected magnitude range of the first signal to maintain the period of the second signal within a selected range of periods for the expected magnitude range of the first signal; e) converting the second signal to a third, analog, signal having a magnitude that varies with variations of the period of the second signal, the third signal having a substantially fixed range of magnitudes for a wide magnitude range of the first signal as a result of selecting the component value in accordance with step (d); and, f) transmitting the third signal to a remote location.
Claim 2
Dependent Claim
203 words
Method for monitoring the condition of a material comprising: a) providing a plurality of different component values and a switch for selecting at least one of the component values; b) providing a first signal having a magnitude indicative of the condition of the material, the magnitude of the first signal varying with variations in the condition; c) converting the first signal to a second signal having a period that varies with variations in the magnitude of the first signal, a range of periods of the second signal being determined by a selected component value; d) selecting one of the component values via the switch depending upon an expected magnitude range of the first signal to maintain the period of the second signal within a selected range of periods for the expected magnitude range of the first signal; e) converting the second signal to a third, analog, signal having a magnitude that varies with variations of the period of the second signal, the third signal having a substantially fixed range of magnitudes for a wide magnitude range of the first signal as a result of selecting the component value in accordance with step (d); and, f) transmitting the third signal to a remote location.
Claim 3
Dependent Claim
235 words
Method for monitoring a condition of a material comprising: a) providing a plurality of different component values and a switch for selecting at least one of the component values; b) providing a first signal having a magnitude indicative of the condition of the material, the magnitude of the first signal varying with variations in the condition; c) converting the first signal to a second signal having a period that varies with variations in the magnitude of the first signal, a range of periods of the second signal being determined by a selected component value; d) selecting one of the component values via the switch depending upon an expected magnitude range of the first signal to maintain the period of the second signal within a selected range of periods for the expected magnitude range of the first signal; e) converting the second signal to a digital duty cycle signal having a duty cycle that varies with variations in the period of the second signal; f) concerting the duty cycle signal to a third, analog, signal having a magnitude that varies with variations of the period of the duty cycle of the duty cycle signal, the third signal having a substantially fixed range of magnitudes for a wide magnitude range of the first signal as a result of selecting the component value in accordance with step (d); and, g) transmitting the third signal to a remote location.
Claim 4
Dependent Claim
235 words
Method for monitoring a condition of a material comprising: a) providing a plurality of different component values and a switch for selecting at least one of the component values; b) providing a first signal having a magnitude indicative of the condition of the material, the magnitude of the first signal varying with variations in the condition; c) converting the first signal to a second signal having a period that varies with variations in the magnitude of the first signal, a range of periods of the second signal being determined by a selected component value; d) selecting one of the component values via the switch depending upon an expected magnitude range of the first signal to maintain the period of the second signal within a selected range of periods for the expected magnitude range of the first signal; e) converting the second signal to a digital duty cycle signal having a duty cycle that varies with variations in the period of the second signal; f) concerting the duty cycle signal to a third, analog, signal having a magnitude that varies with variations of the period of the duty cycle of the duty cycle signal, the third signal having a substantially fixed range of magnitudes for a wide magnitude range of the first signal as a result of selecting the component value in accordance with step (d); and, g) transmitting the third signal to a remote location.
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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) | 1997-01-10 | 1997-07-12 | 1998-01-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-01-10 | 2001-07-12 | 2002-01-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-01-10 | 2005-07-12 | 2006-01-11 | $7700.00 | Window Closed / Lapsed |