GAS-CONCENTRATION DETECTOR SYSTEM

Abstract

A gas-concentration detector system incorporates a temperature sensor, a humidity sensor, and a gas-concentration detector the accuracy of which deviates as a function of temperature and humidity. Contemporaneous, real-time values of temperature, humidity, and gas concentration of a gas of interest are registered and communicated to a data processing system including a computer memory and a computer processor. Value-deviation data reflective of the degree to which the accuracy of the gas-concentration sensor deviates as a function of temperature and humidity are predetermined and stored in the computer memory. Provided with real-time gas-concentration, temperature, and humidity values, the computer processor executes a value-reconciling algorithm which, based on consultation with the stored value-deviation data, calculates and outputs a refined gas-concentration value more is accurately representative of the actual gas-concentration value within the selected environment in which gas-concentration detection and reporting is desired.

Claims

1. A gas-concentration detector system for sensing and reporting concentrations of at least one predetermined gas of interest in a selected environment in which temperature and humidity vary over time, the detector system comprising: a gas-concentration sensor responsive to changes in actual gas-concentration values within the selected environment of the at least one gas of interest, the gas-concentration sensor being configured to generate and communicate raw gas-concentration values that correspond to actual gas-concentration values but reflect projected deviations in gas-concentration sensor responsiveness such that, relative to each predetermined actual gas-concentration value, corresponding raw gas-concentration values deviate from that predetermined actual gas-concentration value as a function of at least one of (i) temperature and (ii) humidity within the selected environment; at least one of a (a) temperature sensor and (b) a humidity sensor configured for registering and communicating, respectively, temperature values and humidity values within the selected environment; a central computer processor communicatively linked to the gas-concentration sensor and the at least one of the at least one temperature sensor and humidity sensor, and configured for receiving, storing, and processing raw gas-concentration values communicated from the gas-concentration sensor and at least one of a temperature value communicated from the temperature sensor and a humidity value communicated from the humidity sensor; and a computer memory within which is stored value-deviation data reflective of amounts by which raw gas-concentration values generated by the gas-concentration sensor deviate from actual gas-concentration values with the selected environment as a function of at least one of temperature values and humidity values within the selected environment; wherein the computer processor is programmed to run a value-reconciling algorithm that receives a raw gas-concentration value corresponding to an actual gas-concentration value, consults the stored value-deviation data, calculates a refined gas-concentration value more accurately representative of the actual gas-concentration value within the selected environment than is the raw gas-concentration value corresponding to the that actual gas-concentration value, and output the refined gas-concentration value.

2. The gas-concentration detector system of claim 1 wherein, relative to each predetermined actual gas-concentration value, corresponding raw gas-concentration values deviate from that predetermined actual gas-concentration value as a function of both temperature and humidity within the selected environment.

3. The gas-concentration detector system of claim 2 wherein the deviation of raw gas-concentration values from the corresponding actual gas-concentration value as a function of at least one of temperature and humidity is non-linear.

4. The gas-concentration detector system of claim 3 wherein the deviation of raw gas-concentration values from the corresponding actual gas-concentration value as a function of both temperature and humidity is non-linear.

5. The gas-concentration detector system of claim 4 wherein the refined gas-concentration value caused to be outputted by the computer processor is further communicated least one of (i) to a programmed machine other than the gas-concentration detector system and (ii) in a human-comprehensible format though a machine-to-human interface associated with the gas-concentration detector system.

6. The gas-concentration detector system of claim 2 wherein the refined gas-concentration value caused to be outputted by the computer processor is further communicated least one of (i) to a programmed machine other than the gas-concentration detector system and (ii) in a human-comprehensible format though a machine-to-human interface associated with the gas-concentration detector system.

7. The gas-concentration detector system of claim 1 wherein the refined gas-concentration value caused to be outputted by the computer processor is further communicated least one of (i) to a programmed machine other than the gas-concentration detector system and (ii) in a human-comprehensible format though a machine-to-human output interface associated with the gas-concentration detector system.

8. The gas-concentration detector system of claim 7 wherein the communicative link between at least two of (i) the gas-concentration sensor, (ii) the temperature sensor, (iii) the humidity sensor, (iv) the central computer processor, (v) the computer memory, (vi) the programmed machine other than the gas-concentration detector system, and (vii) the machine-to-human output interface is wireless.

9. The gas-concentration detector system of claim 1 wherein the communicative link between at least two of (i) the gas-concentration sensor, (ii) the temperature sensor, (iii) the humidity sensor, (iv) the central computer processor, and (v) the computer memory is wireless.

10. The gas-concentration detector system of claim 1 wherein the gas-concentration sensor is a metal oxide semiconductor sensor.

11. The gas-concentration detector system of claim 10 wherein, relative to each predetermined actual gas-concentration value, corresponding raw gas-concentration values deviate from that predetermined actual gas-concentration value as a function of both temperature and humidity within the selected environment.

12. The gas-concentration detector system of claim 11 wherein the deviation of raw gas-concentration values from the corresponding actual gas-concentration value as a function of at least one of temperature and humidity is non-linear.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 is a schematic representation of an illustrative gas-concentration detection system; and

[0019] FIG. 2 is a graphical representation modeling RS/Ro vs. temperature curves at various relative humidities.

DETAILED DESCRIPTION

[0020] The following description of apparatus for and methods of sensing and reporting concentrations of at least one predetermined gas of interest in a selected environment in which temperature and humidity vary over time is illustrative in nature and is therefore not intended to limit the scope of the invention or its application of uses. Accordingly, the various implementations, aspects, versions and embodiments described in the summary and detailed description are in the nature of non-limiting examples falling within the scope of the appended claims and do not serve to restrict the maximum scope of the claims.

[0021] Referring to FIG. 1, the architecture of an illustrative gas-concentration detector system 100 is schematically represented and includes (i) a data processing system 200 including a computer processor 210 and a computer memory 220; (ii) a gas-concentration sensor 300, (iii) a temperature sensor 400, and (iv) a humidity sensor 500. Each of the gas-concentration sensor 300, the temperature sensor 400, and the humidity sensor 500 is communicatively linked to the data processing system 200, either directly or through intermediate data-relaying components (not shown). Moreover, the communicative link(s) between the data-processing system 200 and each of the gas-concentration sensor 300, temperature sensor 400, and humidity sensor 500 may be hardwired or wireless, which is indicated in the schematic by showing the communicative links as both unbroken connecting lines and a plurality of concentric arcs indicative of wave fronts ubiquitously understood as an indication of a wireless link.

[0022] The gas-concentration sensor 300 is configured to register, generate, and communicate raw gas-concentration values V.sub.GCR that correspond to actual gas-concentration values V.sub.GCA but reflect projected deviations in gas-concentration sensor responsiveness such that, relative to each predetermined actual gas-concentration value V.sub.GCA, corresponding raw gas-concentration values V.sub.GCR deviate from that predetermined actual gas-concentration value V.sub.GCA as a function of at least one of (i) temperature and (ii) humidity (e.g., actual moisture content or relative humidity, as described in the summary) within the selected environment.

[0023] In each of various implementations, including the one depicted in FIG. 1, the gas-concentration sensor 300 is an MOS-based sensor in which the electrical resistance across the MOS material varies with changes in temperature and/or humidity. Because disparate actual gas-concentration values V.sub.GCA within the environment in which the gas-concentration sensor 300 is situated correlate to disparate resistance values Ω across the MOS material, constant measurement of resistance values across the MOS material functions “as registration, generation, and communication of raw gas-concentration values V.sub.GCR that correspond to actual gas-concentration values V.sub.GCA.” Moreover, because the precision and accuracy of the MOS sensor deviates as a function of either or both of temperature and humidity, these resistance measurements function as “raw gas-concentration values V.sub.GCR that correspond to actual gas-concentration values V.sub.GCA but reflect projected deviations in gas-concentration sensor responsiveness such that, relative to each predetermined actual gas-concentration value V.sub.GCA, corresponding raw gas-concentration values V.sub.GCR deviate from that predetermined actual gas-concentration value V.sub.GCA as a function of at least one of (i) temperature and (ii) humidity within the selected environment.”

[0024] In order for the gas-concentration detector system 100 to output meaningful gas-concentration information, the degree of deviation between a raw gas-concentration value V.sub.GCR communicated by the gas-concentration sensor 300 and the actual gas-concentration value V.sub.GCA in the relevant environment to which that raw gas-concentration value V.sub.GCA corresponds must be determined. As previously noted, this deviation is most frequently a function of both temperature and humidity within the selected environment at the time a raw gas-concentration value V.sub.GCR is registered by the gas-concentration sensor 300 (i.e., in “real time). Accordingly, the illustrative embodiment of FIG. 1 includes both a (a) temperature sensor 400 configured for registering and communicating to the data processing system 200 real-time temperature values T.sub.RT and (b) a humidity sensor 500 configured for registering and communicating to the data processing system 200 real-time humidity values H.sub.RT within the selected environment.

[0025] The computer processor 210 is configured for receiving, storing, and processing is raw gas-concentration values V.sub.GCR communicated from the gas-concentration sensor 300 as well as temperature values T.sub.RT communicated from the temperature sensor 400 and humidity values H.sub.RT communicated from the humidity sensor 500. More specifically, the computer processor 210 receives and synthesizes raw gas-concentration values V.sub.GCR, temperature values T.sub.RT, and humidity values H.sub.RT, and, by running a value-reconciling algorithm 250, generates and outputs corresponding refined gas-concentration values V.sub.GCRef. There are various methods by which raw gas-concentration values V.sub.GCR can be algorithmically correlated to refined gas-concentration values V.sub.GCRef based on real-time temperature and humidity values T.sub.RT and H.sub.RT, illustrative, non-limiting examples of which are briefly described below.

[0026] In each of various implementations, there is stored in the computer memory 220 value-deviation data 260 reflective of amounts by which raw gas-concentration values V.sub.GCR generated and communicated by the gas-concentration sensor 300 deviate from actual gas-concentration values V.sub.GCA as a function of real-time temperature and humidity values T.sub.RT and H.sub.RT. In one version, pre-correlated, experimentally-determined value-deviation data 260 specific to the gas-concentration sensor 300 embodied in the detector system 100 may by stored in computer memory 220 to serve functionally as a look-up table 265. As described in the summary, the gas-concentration sensor 300 ultimately incorporated into the overall gas-concentration detector system 100 may first be situated in a test environment under which humidity and temperature are experimentally varied and raw-gas concentration values V.sub.GCA are determined relative to that gas-concentration sensor 300, and other gas-concentration sensors fabricated to identical specifications. These raw gas-concentration values V.sub.GCR would then be associated with actual gas-concentration values V.sub.GCA under the various experimental temperature and humidity conditions as determined by other pre-calibrated instruments within the lab environment. That is, the raw gas-concentration values V.sub.GCR would be pre-associated with actual gas-concentration values V.sub.GCA and corresponding, is experimentally set real-time temperature and humidity values T.sub.RT and H.sub.RT in order to construct the value-deviation data 260 (e.g., the lookup table 265).

[0027] Regardless of how the value-deviation data 260 is created, the value-reconciling algorithm 250 receives a real-time temperature value T.sub.RT, a real-time humidity value H.sub.RT, and a raw gas-concentration value V.sub.GCR corresponding to an actual gas-concentration value V.sub.GCA; consults the stored value-deviation data 260; generates a refined gas-concentration value V.sub.GCRef more accurately representative of the actual gas-concentration value V.sub.GCA within the selected environment than is the raw gas-concentration value V.sub.GCR corresponding to that actual gas-concentration value V.sub.GCA; and outputs the refined gas-concentration value V.sub.GCRef.

[0028] In alternative implementations, function lines or curves may be mathematically determined from fewer experimentally determined value-deviation data points in order to create value-deviation data 260. These fewer value-deviation data points could then be mathematically fitted to linear or non-linear functions to extrapolate or interpolate where along these functions other raw versus actual gas-concentration values would reside.

[0029] FIG. 2 is a graphical representation of various experimentally determined “correlation curves” plotted in response to varying, experimentally-controlled environmental conditions. More specifically, sensitivity curves are plotted for three disparate real-time humidity values H.sub.RT in the control environment. For the example shown, the illustrative real-time humidity values H.sub.RT are relative humidities (R.H.) of 35%, 65%, and 95%. Each “humidity curve” relates a resistance ratio of an MOS-based gas-concentration sensor 300 (y-axis) to disparate real-time temperature values T.sub.RT (x-axis) in the control/calibration environment. The resistance ratio is expressed as R.sub.S/R.sub.o, where the value R.sub.S represents the variable resistance of the gas-concentration sensor 300 at a particular real-time humidity value H.sub.RT at various temperature values T.sub.RT in “fresh air” and R.sub.o is the resistance of the gas-concentration sensor 300 at a predetermined set of reference/calibration values (e.g. sensor resistance in “fresh air” at 20° C. and 65% relative humidity). By “fresh air” is meant air as it naturally occurs in an environmental totally devoid of pollutants and/or abnormal concentrations of gases the gas-concentration sensor 300 is designed to detect. The experimental data collected under test conditions at various fixed real-time humidity values H.sub.RT is used to create value-deviation data 260 in a gas-concentration detector system 100 such as that schematically depicted in FIG. 1.

[0030] Out in the field, where real-time gas-concentration detection is to occur, the computer processor 210 accesses raw gas-concentration values V.sub.GCR and real-time temperature and humidity values T.sub.RT and H.sub.RT as they are communicated to the data processing system 200 by the gas-concentration sensor 300, the temperature sensor 400, and the humidity sensor 500. Employing power regression, a new correlation curve is drawn by “squeezing” for the measured real-time humidity value H.sub.RT. The ambient real-time temperature value T.sub.RT is plugged into the approximation equation to yield the corresponding sensitivity ratio for the exact real-time conditions present in the environment. The MOS sensor resistance in fresh air at test conditions is divided by the newly acquired ratio to render a corrected actual sensor resistance which accounts for temperature and humidity changes across time.

[0031] The foregoing is considered to be illustrative of the principles of the invention. Furthermore, since modifications and changes to various aspects and implementations will occur to those skilled in the art without departing from the scope and spirit of the invention, it is to be understood that the foregoing does not limit the invention as expressed in the appended claims to the exact constructions, implementations and versions shown and described.