Patent US3265286A successfully refreshed from Google Patents.
Patent EP0293255A2 successfully refreshed from Google Patents.
EP0293255A2
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EP
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Gas sensing instrument
Assignee: American Intell-Sensors Corp
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Filing: 1988-05-27
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Granted: —
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Expires: 2008-05-27
Abstract
Abstract A gas sensing instrument provides programmable control of the operating temperatures of an array of gas sensors for the detection of target gases in air. The control facilitates precise temperature setpoint resolution. The gas sensors in the array have an improved construction density with reduction in size and an extended operating life provided by reduced power consumption. A programmable circuit functions as a programmable-resistor temperature controller in a Wheatstone bridge configuration. A multiplying digital to analog converter circuit controls the ratio of voltage to current that functions as a resistance equivalent. The programmable circuit is interfaced with a computer to provide selectable temperature control for at least 256 setpoints.
Inventors
- 👤 Richard Grace
- 👤 Alberto M. Guzman
- 👤 Marc A. Portnoff
- 👤 Paul D. Runco
- 👤 Lymperios N. Yannopoulos
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 11:09
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/12; G01N27/122; G01N27/123; G01N33/00; G01N33/0004; G01N33/0009; G01N33/0027; G01N33/0031
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
168 words
An instrument for simultaneously determining the concentrations of a plurality of gases present in air comprising, a microcomputer a plurality of semiconductor gas sensing elements at least equal in number to the number of gases to be detected, said gas sensing elements each having a predetermined response characteristic differing from the response characteristic of the other of said gas sensing elements in response to at least one of the gases to be detected, temperature control means, responsive to said microcomputer, for maintaining each of said gas sensing elements at a selected one of a plurality of operating temperatures, measurement means connected to each of said gas sensing elements for generating a plurality of electrical signals representing the response of each of said respective gas sensing elements to the gases to be detected, said measurement means being electrically connected to said microcomputer, and said microcomputer including means for converting the signals from said measurement means to a digital representation of the concentration of the gases detected in the air.
Claim 2
Dependent Claim
168 words
An instrument for simultaneously determining the concentrations of a plurality of gases present in air comprising, a microcomputer a plurality of semiconductor gas sensing elements at least equal in number to the number of gases to be detected, said gas sensing elements each having a predetermined response characteristic differing from the response characteristic of the other of said gas sensing elements in response to at least one of the gases to be detected, temperature control means, responsive to said microcomputer, for maintaining each of said gas sensing elements at a selected one of a plurality of operating temperatures, measurement means connected to each of said gas sensing elements for generating a plurality of electrical signals representing the response of each of said respective gas sensing elements to the gases to be detected, said measurement means being electrically connected to said microcomputer, and said microcomputer including means for converting the signals from said measurement means to a digital representation of the concentration of the gases detected in the air.
Claim 3
Dependent Claim
49 words
An instrument according to claim 1 which includes, voltage control means for selecting the operating voltage maintained across each gas sensing element, said voltage control means being electrically connected to said microcomputer, and said microcomputer having means for measuring the electrical current through each of said gas sensing elements.
Claim 4
Dependent Claim
60 words
An instrument according to either of claims 1 and 2 in which, said temperature control means includes a Wheatstone bridge, said Wheatstone including a plurality of resistors, and one of said resistors having a resistance value which is selectable corresponding to a selected operating temperature of each of said gas sensing elements in a range from ambient temperature to 600°C.
Claim 5
Independent Claim
114 words
A method for controlling the temperature of a gas sensing element comprising the steps of, supporting a gas sensing element on a substrate, positioning a platinum film element on the substrate, passing current through the platinum film element to heat the substrate and raise the gas sensing element to a preselected temperature for detecting the concentration of a selected gas in air, setting the resistance of the platinum film element at a preselected set-point value, and controlling the current through the platinum film element to adjust the rate of heat generation in the platinum film element to maintain the resistance of the platinum film element at a preselected setpoint value independent of ambient conditions.
Claim 6
Independent Claim
114 words
A method for controlling the temperature of a gas sensing element comprising the steps of, supporting a gas sensing element on a substrate, positioning a platinum film element on the substrate, passing current through the platinum film element to heat the substrate and raise the gas sensing element to a preselected temperature for detecting the concentration of a selected gas in air, setting the resistance of the platinum film element at a preselected set-point value, and controlling the current through the platinum film element to adjust the rate of heat generation in the platinum film element to maintain the resistance of the platinum film element at a preselected setpoint value independent of ambient conditions.
Claim 7
Dependent Claim
35 words
A method according to claim 4 which includes, maintaining the resistance of the platinum film element at a preselected magnitude to maintain the temperature of the substrate at a preselected magnitude independent of ambient conditions.
Claim 8
Independent Claim
189 words
A method according to either of claims 4 and 5 which includes, controlling the resistance of the platinum film element by a Wheatstone bridge circuit connected thereto, and providing as one of a plurality of resistors in the Wheatstone bridge a digital to analog converter having a resistance value selectable to maintain the temperature of the platinum film heater and substrate at a selected one of a plurality of discrete temperatures in the range from ambient temperature to 600°C. means for supplying a voltage to said electrodes to apply a voltage to said gas sensing material, a resistance measuring device connected to said electrodes, said resistance measuring device being operable to convert the values of the electrical resistances of said electrodes to a plurality of digital output signals, signal processing means for receiving said digital output signals from said resistance measuring device, means for transmitting the value of said electrical resistances in the form of said digital output signals to said signal processing means, and said signal processing means converting said digital output signals to a quantitative measurement of the concentrations of the plurality of target gases in air.
Claim 9
Independent Claim
108 words
A method according to any one of claims 4 to 6 which includes, measuring the concentration of a selected gas in air by heating the gas sensing element to a preselected temperature on the substrate, varying the resistance of the platinum film element to change the temperature of the substrate and set the temperature of the gas sensing element at selected discrete magnitude in the range from ambient temperature to 600°c, and individually measuring the concentration of a plurality of discrete gases in air by setting the temperature of the gas sensing element to a preselected temperature in said range corresponding to the desired gas to be detected.
Claim 10
Independent Claim
54 words
A system for simultaneous detection of a plurality of target gases in air comprising, a plurality of gas sensors, each of said gas sensors including a layer of gas sensing material, means for supporting each layer of gas sensing material, a pair of metallic electrodes in contact with each layer of gas sensing material,
Claim 11
Independent Claim
54 words
A system for simultaneous detection of a plurality of target gases in air comprising, a plurality of gas sensors, each of said gas sensors including a layer of gas sensing material, means for supporting each layer of gas sensing material, a pair of metallic electrodes in contact with each layer of gas sensing material,
Claim 12
Dependent Claim
53 words
A system according to claim 8 which includes, voltage reference means for maintaining a fixed voltage reference across said electrodes, means for supplying digital input to said signal processing means for determining the resistance of said electrodes and setting a desired reference voltage by transmitting a digital signal to said voltage reference means.
Claim 13
Independent Claim
61 words
A system according to either of claims 8 and 9 in which, each layer of gas sensing material includes a semiconductor metal oxide material, said means for supporting said layers of gas sensing material including a substrate in contact with said electrodes, and a platinum film heater positioned on said substrate oppositely of each of said layers of gas sensing material.
Claim 14
Dependent Claim
149 words
A gas detecting instrument comprising, a plurality of electrically insulating substrates, at least a single pair of electrodes positioned on each of said substrates, a layer of gas sensing material in contact with said electrodes on each of said substrates, a voltage source connected to said electrodes, means for controlling the temperature of each of said gas sensing materials at preselected values, means for measuring the electrical resistance of said gas sensing material in response to a plurality of gases to be detected in air, an analog to digital converter connected to said means for measuring the electrical resistance for converting the value of the measured electrical resistance to a digital representation, and a signal processor connected to said analog to digital converter for receiving the measurement of the electrical resistance in said digital representations and computing the value of the gas concentrations detected from the electrical resistance measurements.
Claim 15
Dependent Claim
149 words
A gas detecting instrument comprising, a plurality of electrically insulating substrates, at least a single pair of electrodes positioned on each of said substrates, a layer of gas sensing material in contact with said electrodes on each of said substrates, a voltage source connected to said electrodes, means for controlling the temperature of each of said gas sensing materials at preselected values, means for measuring the electrical resistance of said gas sensing material in response to a plurality of gases to be detected in air, an analog to digital converter connected to said means for measuring the electrical resistance for converting the value of the measured electrical resistance to a digital representation, and a signal processor connected to said analog to digital converter for receiving the measurement of the electrical resistance in said digital representations and computing the value of the gas concentrations detected from the electrical resistance measurements.
Claim 16
Dependent Claim
39 words
A gas detecting instrument according to claim 11 which includes, means for controlling the voltage applied across each layer of said gas sensing material, and means for adjusting the temperature of each of said substrates to discrete selectable temperatures.
Claim 17
Dependent Claim
97 words
A gas detecting instrument according to either of claims 11 and 12 in which, said means for controlling temperature includes a Wheatstone bridge circuit, a platinum film heater electrically connected to each substrate and to said circuit, said circuit including a resistor element being selectively adjustable to a preselected resistance to maintain said substrate at a preselected temperature, and a digital to analog converter electrically connected to said signal processor for selecting the resistance of said resistor element corresponding to a preselected temperature at which each of said layers of gas sensing material are to be maintained.
Claim 18
Dependent Claim
56 words
A gas detecting instrument according to any one of claims 11 to 13 which includes, means for maintaining a selected voltage to said electrodes and applied to each of said layers of gas sensing material, and said signal processing means being operable to measure the current flowing through each of said layers of gas sensing material.
Claim 19
Dependent Claim
76 words
A gas detecting instrument according to any one of claims 11 to 14 in which said means for controlling the temperature includes, a platinum film heater connected to each of said insulating substrates for heating said gas sensing material thereon, and said means for selectively controlling the temperature of said respective platinum film heaters and accordingly said layers of gas sensing material by maintaining the electrical resistance of said platinum film heaters at preselected fixed values.
References Cited (Backward Citations)
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