Infrared source modulation and system using same

• US 20050285055A1
• Filed: 06/10/2005
• Published: 12/29/2005
• Est. Priority Date: 06/29/2004
• Status: Active Grant

• Current Assignee: Philips RS North America LLC (Koninklijke Philips N.V.)
• Original Assignee: RIC INVESTMENTS LLC (Respironics Incorporated)
• Inventors: Perry, Anthony T., DelFavero, John R.
• Granted Patent: US 7,291,851 B2
• Time in Patent Office: Days
• US Class Current: 250/504.00R
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 5/0896 using a light source, e.g. for illuminating a surface
• 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 2201/0692 Regulated sources; stabilised supply

Abstract

A method of modulating an infrared radiation (IR) source that includes applying a time-varying, periodic voltage signal to the IR source, measuring a parameter of the voltage signal, and adjusting the voltage signal to maintain a substantially constant delivered power to the IR source. Adjusting the voltage signal is done based on the measured parameter and a predetermined relationship between the measured parameter of the voltage pulse and a resistance of such an infrared radiation source. Alternatively, the method includes applying a the voltage pulse, measuring a first parameter of the voltage pulse and a second parameter of a current passing through the infrared radiation source resulting from the applying step, and adjusting the voltage pulse to maintain a substantially constant delivered power to the infrared radiation source based on the first parameter and the second parameter.

Claims

1. A method of regulating infrared radiation output from an infrared radiation source comprising:

applying a time-varying, periodic voltage signal to an infrared radiation source;

measuring a parameter of the voltage signal; and

adjusting the voltage signal to maintain a substantially constant delivered power to such an infrared radiation source, wherein adjusting the voltage signal is accomplished based on the measured parameter and a predetermined relationship between the measured parameter of the voltage signal and a resistance of such an infrared radiation source.

2. The method of claim 1, wherein the voltage signal is a uni-polar or a bi-polar voltage pulse.

3. The method of claim 1, wherein the parameter of the voltage signal is amplitude.

4. The method of claim 2, wherein adjusting the voltage signal includes adjusting a width of a voltage pulse in the voltage signal.

5. A method of regulating infrared radiation output from an infrared radiation source comprising:

applying a voltage pulse to an infrared radiation source, wherein the voltage pulse has a duty cycle less than 100%;

measuring a first parameter of the voltage pulse;

measuring a second parameter of a current passing through the infrared radiation source resulting from the applying step; and

adjusting the voltage pulse to maintain a substantially constant delivered power to the infrared radiation source based on the first parameter and the second parameter.

6. The method of claim 5, wherein the voltage pulse is a uni-polar or a bi-polar voltage.

7. The method of claim 5, wherein the parameter of the voltage pulse is amplitude.

8. The method of claim 5, wherein adjusting the voltage pulse includes adjusting a width of the voltage pulse.

9. A system for generating pulses of infrared radiation comprising:

an infrared radiation source;

a current sensor operatively coupled to the infrared radiation source so as to measure an electrical current passing through the infrared radiation source;

a voltage sensor coupled to the infrared radiation source so as to measure an electrical voltage applied to the infrared radiation source; and

means for applying electrical pulses to the infrared radiation source such that a substantially constant power is delivered to the infrared radiation source.

10. The system of claim 9, wherein the infrared radiation source comprises an emissive, electrically resistive material.

11. The system of claim 9, wherein the means for applying electrical pulses includes a uni-polar supply voltage.

12. The system of claim 11, wherein the voltage sensor measures the uni-polar supply voltage.

13. The system of claim 9, wherein the means for applying electrical pulses includes a bi-polar supply voltage.

14. The system of claim 13, where the voltage sensor measures the bi-polar supply voltage.

15. The system of claim 9, wherein the current sensor comprises a sense resistor and a measurement circuit to measure the voltage across the sense resistor.