Gas analyzer and gas analyzing method
First Claim
1. A method for producing synchronizing pulses in a gas analyzer having a sample cell for containing a gas mixture to be analyzed, means for producing and directing infrared energy through the sample cell, means for detecting the infrared energy passing through the sample cell and producing an electrical signal representative thereof, means coupled to the detecting means for processing the electrical signal to produce an output indicating the concentration of the constituents of the gas in the sample cell, and a rotary filter wheel for successively and repetitively positioning at least one filter in the path of the infrared energy, said method comprising detecting a preselected rising or falling portion of said electrical signal representative of the infrared energy, and developing the synchronizing signals at a fixed time relationship to said rising or falling portion.
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Accused Products
Abstract
A gas analyzer and gas analyzing method are described of the non-dispersive infrared type wherein infrared energy is passed through a sample cell containing an unknown mixture of gas. The infrared energy passing through the cell is received by a detector and an electrical signal is produced representative thereof. A rotary filter wheel positions at least one filter in the path of the infrared energy, resulting in a pulsating detector output. The electrical signal is processed to produce an output indicating the concentration of the constituents of the gas mixture in the sample cell. Synchronization with the processed electrical signal is obtained by deriving synchronizing pulses directly from the electrical signal produced by the detector.
15 Citations
9 Claims
- 1. A method for producing synchronizing pulses in a gas analyzer having a sample cell for containing a gas mixture to be analyzed, means for producing and directing infrared energy through the sample cell, means for detecting the infrared energy passing through the sample cell and producing an electrical signal representative thereof, means coupled to the detecting means for processing the electrical signal to produce an output indicating the concentration of the constituents of the gas in the sample cell, and a rotary filter wheel for successively and repetitively positioning at least one filter in the path of the infrared energy, said method comprising detecting a preselected rising or falling portion of said electrical signal representative of the infrared energy, and developing the synchronizing signals at a fixed time relationship to said rising or falling portion.
- 4. In a gas analyzer comprising a sample cell for containing gas to be analyzed, means for producing and directing infrared energy through said sample cell, means for detecting the infrared energy passing through said sample cell and producing an electrical signal representative thereof, means coupled to said detecting means for processing the electrical signal to produce an output indicating the concentration of the constituents of the gas in said sample cell, and a rotary filter wheel for successively and repetitively positioning at least one filter in the path of the infrared energy, the improvement which comprises means for detecting a preselected rising or falling portion of said electrical signal representative of the infrared energy, and means for developing synchronizing signals at a fixed time relationship to said rising or falling portion and applying said synchronizing signals to said processing means.
- 7. A gas analyzer comprising, a sample cell for containing gas to be analyzed, means for producing and directing infrared energy through said sample cell, means for detecting the infrared energy passing through said sample cell and producing an electrical signal representative thereof, means coupled to said detecting means for processing the electrical signal to produce an output indicating the concentration of the constituents of the gas mixture in said sample cell, a rotary filter wheel for successively and repetitively positioning at least one filter in the path of the infrared energy, and synchronizing means connected to said electrical signal processing means for providing synchronizing pulses thereto, said synchronizing means being coupled to said detecting means and being responsive to the electrical signal produced thereby to produce the synchronizing pulses.
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9. A gas analyzer comprising, a sample cell for containing a gas mixture to be analyzed, means for producing and directing infrared energy through said sample cell, means for detecting the infrared energy passing through the sample cell and producing an electrical signal representative thereof, a rotary filter wheel for successively and repetitively positioning at least a pair of filters in the path of the infrared energy, gain controlled amplifier means coupled to the output of said detecting means, demodulator means coupled to the output of said gain controlled amplifier means for providing an output signal representing the concentration of the constituents of the gas in said sample cell, an automatic gain control servo-loop coupling the output of said gain controlled amplifier means back thereto for controlling the gain thereof, comparator means coupled to the output of said gain controlled amplifier means and operable to provide a controlling output when the amplitude of the output of said gain controlled amplifier means exceeds a predetermined level, switch control means connected to the output of said comparator means for providing switch control signals in a preselected time sequence, first switch means for controlling said automatic gain controlled servo-loop and operable by said switch control means, second switch means coupled to the output of said gain controlled amplifier means for clamping same to ground in response to signals applied thereto by said switch control means, and third switch means connected between the output of said gain controlled amplifier means and said demodulator means and responsive to signals applied thereto from said switch control means, whereby suitable sequencing of said first, second, and third switch means provides a span stabilized phase sensitive demodulated signal.
Specification