US 12,216,049 B2
Gas sensors
Håkon Sagberg, Oslo (NO); Britta Grennberg Fismen, Oslo (NO); Kari Anne Hestnes Bakke, Hvittingfoss (NO); Jon Tschudi, Oslo (NO); Ib-Rune Johansen, Oslo (NO); and Knut Baeroe Sandven, Oslo (NO)
Assigned to DRÄGER SAFETY AG & CO. KGaA, Lübeck (DE)
Filed by DRÄGER SAFETY AG & CO. KGaA, Lübeck (DE)
Filed on Feb. 24, 2022, as Appl. No. 17/679,650.
Application 17/679,650 is a continuation in part of application No. 17/119,472, filed on Dec. 11, 2020, abandoned.
Application 17/119,472 is a continuation of application No. 14/362,944, abandoned, previously published as PCT/GB2012/053021, filed on Dec. 5, 2012.
Claims priority of application No. 1120871 (GB), filed on Dec. 5, 2011.
Prior Publication US 2022/0276159 A1, Sep. 1, 2022
Int. Cl. G01N 21/3504 (2014.01); G01N 21/31 (2006.01); G01R 27/26 (2006.01)
CPC G01N 21/3504 (2013.01) [G01N 21/314 (2013.01); G01R 27/2605 (2013.01); G01N 2021/317 (2013.01); G01N 2021/3513 (2013.01); G01N 2201/061 (2013.01); G01N 2201/0693 (2013.01); G01N 2201/0696 (2013.01); G01N 2201/12761 (2013.01); G01N 2201/12784 (2013.01); G01N 2201/128 (2013.01)] 22 Claims
OG exemplary drawing
 
1. A gas sensor for measuring a concentration of a gas, the gas sensor comprising:
a light source configured to be switched on to emit light and to be switched off;
a measurement volume;
a detector configured to receive light that has passed through the measurement volume to output a photo detector signal;
an adaptable filter disposed between the light source and the detector and having a measurement state in which the adaptable filter passes at least one wavelength band which is absorbed by the gas and a reference state in which said at least one wavelength band is attenuated relative to the measurement state; and
a controller connected to each of the light source, the detector and the adaptable filter, the controller being configured:
to switch the adaptable filter between the measurement state and the reference state;
to switch on the light source at a start of a gas sensor operation period and to control power to the light source such that the light source emits a pulse of light above a predetermined threshold during said gas sensor operation period;
to switch off the light source at an end of the gas sensor operation period so as to enter a low power or shutdown mode, wherein the light source is switched off during the low power or shutdown mode, and wherein:
the control of power to the light source during said gas sensor operation period includes initiating an initial powering of the light source as a part of the light source emitting the pulse of light;
the control of power to the light source during said gas sensor operation period includes controlling power to the light source during a measurement stage of the gas sensor operation period as a part of the light source emitting the pulse of light based on controlling the light source to a desired source temperature followed by the light source falling below the desired source temperature;
the control of power to the light source during said gas sensor operation period includes controlling power to the light source during a dark signal stage, following the initial powering and prior to the measurement stage, of the gas sensor operation period as a part of the light source emitting the pulse of light;
the control of power to the light source during said gas sensor operation period includes controlling power to the light source during a ramp-up time, after the dark signal stage and prior to the measurement stage, of the gas sensor operation period as a part of the light source emitting the pulse of light, based on controlling the light source to step-wise or continuously increase the source temperature to surpass the desired source temperature and thereafter to control the light source at the correct source temperature; and
the switching of the adaptable filter comprises changing the adaptable filter between one said measurement state and one said reference state during the measurement stage of said gas sensor operation period and subsequent to the light source reaching the desired source temperature and prior to the light source falling below the desired source temperature;
to sample the photo detector signal during the dark signal stage, subsequent to the initiating the initial powering of the light source and prior to the ramp-up time;
to sample the photo detector signal with the adaptable filter in the measurement state during said gas sensor operation period, subsequent to the light source reaching the desired source temperature and prior to the light source falling below the desired source temperature; and
to sample the photo detector signal with the adaptable filter in the reference state during said gas sensor operation period, subsequent to the light source reaching the desired source temperature and prior to the light source falling below the desired source temperature.