Digital gas detector and noise reduction techniques
OwnerMark Goldstein, Eric Gonzalesinventors
Life of this patent
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Abstract
A sensor apparatus incorporates a responding gas sensor to measure and display gas concentrations or other indications. Calculation of a gas concentration may be derived from an output signal of a light detector through the use of a linear equation. Through the use of digital processing an output signal may be sampled to calculate a gas concentration based on a rate of change of the output voltage.
Claims43
An apparatus for sensing the presence of a target gas, comprising:
- a light source;
- a sensor having an optical characteristic that varies in accordance with a concentration of a target gas;
- a light detector optically coupled with the sensor and the light source to detect light that passed from the light source through the sensor, the light detector configured to generate an output signal in accordance with the detected light;
- and
- a processor coupled to the light detector and adapted to calculate a concentration level of the target gas in accordance with a rate of change of the output signal and at least one predefined slope, the processor further adapted to provide at least one indication in accordance with the calculated concentration level.
A method of digitally determining a concentration of a target gas using an optical gas sensor system, comprising:
- measuring an output signal associated with an optical transmittance value of a sensor upon exposure to a target gas;
- subtracting the values of the output signal at a first time and an earlier second time to determine a rate of change of the output signal between the two times;
- calculating a concentration level of the target gas using the rate of change, the value of the output signal at the first time and at least one predefined slope;
- and
- providing a tangible output event in accordance with the calculated concentration level.
A method for sensing the presence of a target gas, comprising:
- providing a sensor having an optical characteristic that varies in accordance with a concentration of a target gas;
- making a plurality of initial readings of the sensor;
- making a plurality of subsequent readings of the sensor, each subsequent reading being made a predetermined time after an adjacent initial reading;
- subtracting the initial readings from adjacent subsequent readings to produce a plurality of differences;
- dividing the differences to produce a rate of change for an output signal;
- multiplying the rate of change by a predetermined slope to provide a product value;
- and
- adding a predetermined constant to the product value to provide a concentration level of the target gas.
A method for identifying an end-of-life condition of a sensor, comprising:
- providing a sensor having an optical characteristic that varies in accordance with a concentration of a target gas;
- detecting light that passed through the sensor;
- generating an output signal in accordance with the detected light;
- converting the output signal to a digital signal;
- and
- identifying an end-of-life condition for the sensor in accordance with a value of the digital signal.
An apparatus for sensing the presence of a target gas, comprising:
- a light source;
- a sensor having an optical characteristic that varies in accordance with a concentration of a target gas;
- a light detector optically coupled with the sensor and the light source to detect light that passed from the light source through the sensor, the light detector being configured to generate, in response to the detected light, an output signal within an operating range such that at least one substantially linear output signal range is provided within the operating range;
- an analog to digital converter coupled to the light detector for converting the output signal to a digital output signal;
- and
- a processor coupled to receive the digital output signal from the analog to digital converter, the processor adapted to calculate a concentration level of the target gas in accordance with the at least one substantially linear output signal range, the processor further adapted to provide at least one indication in accordance with the calculated concentration level.
A sensing device that reduces noise and interference from EMI by making the sensing elements conductive, the sensing device comprising a conductive plastic sensor housing about any sensor or a metal housing or a mixture of an inert layer being insulation and an outer layer being conductive.
A sensing device that reduces noise in the signal of an optical sensor that uses conductive plastic housing to surround the optical sensing components, the sensing device comprising an LED and a Photodiode and a sensing element located between the photon path of the LED and the Photodiode that change its optional transmission as a function of a gas to be measured.
Dependencies are inferred from the claim text.