초록 ▼

Gas analyzers of the non-dispersive infrared radiation type which are designed to measure the concentration of one gas in a mixture of gases containing that gas. A novel, electrically modulated, stable, thick film infrared radiation emitter is employed to emit a beam of collimated, focused energy; a

Gas analyzers of the non-dispersive infrared radiation type which are designed to measure the concentration of one gas in a mixture of gases containing that gas. A novel, electrically modulated, stable, thick film infrared radiation emitter is employed to emit a beam of collimated, focused energy; and two electrically biased detectors are preferably used so that a ratioed, error eliminating output signal can be supplied to the failsafe, signal processing circuitry of the analyzer. The latter, and a conventional analog-to-digital convertor, supply information to a microcomputer which: (1) turns the infrared radiation emitter on and off; (2) controls a heater which keeps the infrared radiation detectors at a constant, precise temperature; and (3) controls displays of a variety of information concerning the gas being measured and the status of the gas analyzer. The microcomputer also accepts ambient temperature, barometric pressure, and other compensation factors. Typically, a disposable airway adapter will be included in the gas analyzer to confine the mixture of gases being analyzed to a path having a transverse dimension of precise and specific length and to provide an optical path across that stream of gases between the infrared radiation emitter and the infrared radiation detectors. The emitter and detectors are incorporated in a transducer head which can be detachably fixed to the airway adapter.

대표청구항 ▼

A device for emitting modulated infrared energy in a stable, repeatable manner, said device comprising: a non-metallic substrate fabricated of a material possessing low thermal conductivity; a layer of an emissive, electrically resistive material on said substrate; and means for applying pulses of e

A device for emitting modulated infrared energy in a stable, repeatable manner, said device comprising: a non-metallic substrate fabricated of a material possessing low thermal conductivity; a layer of an emissive, electrically resistive material on said substrate; and means for applying pulses of electrical energy across said layer of emissive, electrically resistive material to periodically produce the wanted emission of infrared energy therfrom, the means for applying said pulses across said emissive layer comprising an operatioonal amplifier, electronic switch means for so applying a signal to one input of said operational amplifier as to cause a signal to appear at the output of said operational amplifier, means responsive to the appearance of said output signal to connect said emissive layer across two power sources of equal magnitude but opposite polarity, and a differential resistor network for precisely controlling the voltage thus applied across said emissive layer, said differential resistor network comprising one pair of resistors connected in series between one side of said emissive layer and ground and a second pair of resistors connected in series between the other side of said emissive layer and a lead routing the input signal to said operational amplifier, the resistors in one of said pairs being matched to the resistors in the other of said pairs.