APPARATUS AND METHOD FOR CONTROLLING RADIATION SOURCE VARIABILITY FOR OPTICAL GAS MEASUREMENT SYSTEMS

• US 20140052003A1
• Filed: 04/04/2012
• Published: 02/20/2014
• Est. Priority Date: 04/26/2011
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Pierry, Anthony, Jiang, Zhi-Xing
• Granted Patent: US 10,702,187 B2
• Time in Patent Office: Days
• US Class Current: 600/475
• CPC Class Codes: A61B 5/082 Evaluation by breath analysis, e.g. determination of the chemical composition of exhaled breath A61B5/083, A61B5/091 take precedence
• CPC Class Codes: G01J 3/108 for measurement in the infrared range
• CPC Class Codes: G01N 21/274 Calibration, base line adjustment, drift correction
• CPC Class Codes: G01N 21/3504 for analysing gases, e.g. multi-gas analysis
• CPC Class Codes: G01N 21/85 Investigating moving fluids or granular solids

Abstract

An infrared detector includes a radiation source configured to emit electromagnetic radiation. The detector includes a source monitoring apparatus configured to generate output signals (62) related to electrical resistance through the radiation source. The output signals are used to account for radiation source temperature in measurements by the detector. The output signals may be used (72) in the provision of power to the radiation source to maintain the temperature of the detector at a beneficial level. The detector is configured to monitor a level of a gaseous molecular species within a flow of breathable gas.

Claims

1. A detector configured to monitor a level of a gaseous molecular species within a flow of breathable gas, the detector comprising:

a source configured to emit electromagnetic radiation;

source optics configured to direct electromagnetic radiation emitted by the source across a flow path of a flow of breathable gas that communicates with an airway of a subject;

a radiation sensor assembly configured to receive electromagnetic radiation that has been emitted by the source and has passed through the flow path, the sensor assembly being further configured to generate output signals that convey information related to a parameter of the received electromagnetic radiation;

a source monitoring apparatus configured to generate output signals that convey information related to electrical resistance through the source; and

a processors configured to determine a level of a gaseous molecular species within the flow of breathable gas in the flow path (i) based on the output signals generated by the radiation sensor assembly and (ii) further based on the output signals generated by the source monitoring apparatus to account for the electrical resistance through the source, wherein the processor is further configured to estimate irradiance of the radiation source based on the output signals generated by the source monitoring apparatus, to determine measured irradiance received at the radiation sensor assembly based on the output signals generated by the radiation sensor assembly, and to compare the estimated irradiance with the measured irradiance to determine a difference, still further wherein responsive to a determination that the difference between the estimated irradiance and the measured irradiance breaches a threshold, the processor generates a notification to initiate a recalibration of the radiation sensor assembly.

2. The system of claim 1, wherein determining the level of the gaseous molecular species based on the output signals generated by the source monitoring apparatus effectively adjusts the level determination for the temperature of the source.

4. The system of claim 1, wherein the processor is further configured to control provision of power to the source dynamically based on the electrical resistance through the source.

5. The system of claim 1, wherein the processor is further configured to implement the estimated irradiance as a reference irradiance in determining the level of a gaseous molecular species.

3. (canceled)

6. A method of monitoring a level of a gaseous molecular species within a flow of breathable gas, the method comprising:

directing electromagnetic radiation emitted by a radiation source across a flow path of a flow of breathable gas that communicates with an airway of a subject;

receiving electromagnetic radiation that has been emitted and has passed through the flow path;

generating output signals that convey information related to a parameter of the received electromagnetic radiation;

generating output signals that convey information related to electrical resistance through the source; and

determining a level of a gaseous molecular species within the flow of breathable gas in the flow path (i) based on the output signals conveying information related to the parameter of the received electromagnetic radiation and (ii) further based on the output signals conveying information related to the electrical resistance through the source, further comprising estimating irradiance of the radiation source based on the output signals related to the electrical resistance through the source, determining measured irradiance received based on the output signals that convey information related to a parameter of the received electromagnetic radiation, and comparing the estimated irradiance with the measured irradiance to determine a difference, still further wherein responsive to a determination that the difference between the estimated irradiance and the measured irradiance breaches a threshold, generating a notification to initiate a recalibration of the radiation sensor assembly.

7. The method of claim 6, wherein determining the level of the gaseous molecular species based on the output signals conveying information related to the electrical resistance through the source effectively adjusts the level determination for the temperature of the source.

9. The method of claim 6, further comprising controlling the provision of power to the source dynamically based on the electrical resistance through the source.

10. The method of claim 6, wherein the determination of estimating irradiance of the radiation source based on the output signals conveying information related to electrical resistance implements the estimated irradiance as a reference irradiance.

8. (canceled)

11. A system for monitoring a level of a gaseous molecular species within a flow of breathable gas, the system comprising:

means for directing electromagnetic radiation emitted by a radiation source across a flow path of a flow of breathable gas that communicates with an airway of a subject;

means for receiving electromagnetic radiation that has been emitted and has passed through the flow path;

means for generating output signals that convey information related to a parameter of the received electromagnetic radiation;

means for generating output signals that convey information related to electrical resistance through the source; and

means for determining a level of a gaseous molecular species within the flow of breathable gas in the flow path based on the output signals conveying information related to the parameter of the received electromagnetic radiation, and (ii) further based on the output signals conveying information related to the electrical resistance through source to account for the electrical resistance through the source, further comprising means for estimating irradiance of the radiation source based on the output signals related to the electrical resistance through the source, means for determining measured irradiance received based on the output signals that convey information related to a parameter of the received electromagnetic radiation, and means for comparing the estimated irradiance with the measured irradiance to determine a difference, still further wherein responsive to a determination that the difference between the estimated irradiance and the measured irradiance breaches a threshold, generating a notification to initiate a recalibration of the radiation sensor assembly.

12. The system of claim 11, wherein the means for determining the level of the gaseous molecular species based on the output signals conveying information related to the electrical resistance through the source effectively adjusts the level determination for the temperature of the source.

14. The system of claim 11, further comprising means for controlling the provision of power to the source dynamically based on the electrical resistance through the source.

15. The system of claim 11, wherein the means for determining the level of gaseous molecular species implements the estimated irradiance as a reference irradiance in determining the level of the gaseous molecular species.

13. (canceled)