US5034725A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Semiconductor gas sensor having linearized indications
Assignee: WEST ACQUISITION GROUP Inc
•
Filing: 1990-07-11
•
Granted: 1991-07-23
•
Expires: 2010-07-11
Abstract
Abstract Atmospheric concentrations of reducing gases are measured and indicated by a gas sensor whose conductivity varies in accordance with variations in the concentration of ambient reducing gases, a resistance in series with the gas sensor for establishing a reference voltage, a circuit interconnecting the resistance with a linearizing circuit including the non-inverting inputs of a plurality of voltage comparators and with the inverting input of a fault detecting comparator, an adjustable resistance of a magnitude substantially equal to the response of the sensor at its maximum value, a thermistor in parallel with a fixed resistance and in series with the adjustable resistance and with a voltage divider including a plurality of fixed resistors respectively connected with the inverting inputs of the plurality of voltage comparators together with a light emitting diode in series with the output of each voltage comparator, each light emitting diode indicating a concentration of an ambient reducing gas in terms of parts per million, and the non-inverting input of the fault detecting comparator is connected with a reference voltage to indicate an open circuit condition.
Inventors
- 👤 Thomas C. Sorensen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 04:27
CPC Classifications
G; G08; G08B; G08B17/00; G08B17/10; G08B17/117
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
144 words
A combination which includes semiconductor elements for measuring atmospheric concentrations of reducing gases comprising a gas sensor whose conductivity varies in accordance with variations in the concentration of ambient reducing gases, resistance means in series with said gas sensor for establishing a reference voltage, circuit means interconnecting said resistance means with the non-inverting inputs of a plurality of voltage comparators, an adjustable resistance means of a magnitude substantially equal to the response of said sensor at its maximum value, a thermistor in parallel with a fixed resistance and in series with said adjustable resistance means and with a voltage divider comprising a plurality of fixed resistors respectively connected with the inverting inputs of said plurality of voltage comparators, and a light emitting diode in series with the output of each of said comparators for selectively indicating a particular degree of ambient reducing gas concentrations.
Claim 2
Dependent Claim
144 words
A combination which includes semiconductor elements for measuring atmospheric concentrations of reducing gases comprising a gas sensor whose conductivity varies in accordance with variations in the concentration of ambient reducing gases, resistance means in series with said gas sensor for establishing a reference voltage, circuit means interconnecting said resistance means with the non-inverting inputs of a plurality of voltage comparators, an adjustable resistance means of a magnitude substantially equal to the response of said sensor at its maximum value, a thermistor in parallel with a fixed resistance and in series with said adjustable resistance means and with a voltage divider comprising a plurality of fixed resistors respectively connected with the inverting inputs of said plurality of voltage comparators, and a light emitting diode in series with the output of each of said comparators for selectively indicating a particular degree of ambient reducing gas concentrations.
Claim 3
Dependent Claim
42 words
A combination of semi conductor elements according to claim 1 wherein said gas sensor includes a heater and wherein the resistance of, said sensor is inversely proportional to the ambient reducing gas concentration when the voltage of said heater is held constant.
Claim 4
Dependent Claim
35 words
A combination of semiconductor elements according to claim 2 wherein the resistance of said sensor varies in a non linear fashion and wherein said thermistor compensates for changes in said sensor due to temperature changes.
Claim 5
Dependent Claim
26 words
A combination of semiconductor elements according to claim 1 wherein said voltage divider establishes a precision reference voltage to the inverting input of each said comparators.
Claim 6
Dependent Claim
25 words
A combination of semiconductor elements according to claim 4 wherein said precision reference voltages are determined in conjunction with empirical response data of said sensor.
Claim 7
Dependent Claim
33 words
A combination of semiconductor elements according to claim 5 wherein gas concentration in parts per million is indicated by sequential energization of said light emitting diodes in accordance with increasing concentration of gas.
Claim 8
Dependent Claim
49 words
A combination of semiconductor elements according to claim 6 wherein a particular comparator output goes high and its associated light emitting diode is turned on in coordination with the equalization of the sensor voltage and the voltage at the associated fixed resistor thereby to indicate parts per million visually.
Claim 9
Dependent Claim
56 words
A combination of semiconductor elements according to claim 1 wherein a summing network includes a plurality of equal fixed resistors to which the outputs of the comparators are respectively connected and the outputs of which are interconnected with each other and with an inverting amplifier to combine the outputs of said comparators to a scaled value.
Claim 10
Dependent Claim
39 words
A combination of semiconductor elements according to claim 8 wherein the scaled value of said combined output is supplied to an inverting amplifier to provide a positive output that is a linear representation of the percentage of gas concentration.
Claim 11
Dependent Claim
21 words
A combination of semiconductor elements according to claim 9 where said positive output is converted to an output of 4-20 mA.
Claim 12
Dependent Claim
51 words
A combination of semiconductor elements according to claim 1 wherein the outputs of said comparators are respectively connected with one terminal of a multiple position selector the other terminal of each of which is connected with the inverting input of an alarm device and to an alarm indicator and a relay.
Claim 13
Dependent Claim
41 words
A combination of semiconductor elements according to claim 1 wherein the inverting input of a fault detecting comparator is connected with said circuit means and the non-inverting input of said comparator is connected with a reference voltage indicating an open condition.
Claim 14
Dependent Claim
52 words
A combination of semiconductor elements according to claim 12 wherein the output of said fault detecting comparator is connected with a light emitting diode which is energized in response to failure of said sensor when the sensor output voltage is zero which results in a high output of said fault detecting comparator.
Claim 15
Dependent Claim
47 words
A combination of series conductor elements according to claim 13 wherein a pair of parallel connected diodes are connected in series with a resistor and with the base of a transistor the collector of which is connected with a reset diode to provide fault and reset indications.
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) | 1994-07-22 | 1995-01-21 | 1995-07-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-07-22 | 1999-01-21 | 1999-07-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-07-22 | 2003-01-21 | 2003-07-23 | $7700.00 | Window Closed / Lapsed |