Coulter Electronics, Inc.

Steven N Kolber

Wallace H Coulter

Ernesto Bello

Robert L Kreiselman

Anthony Marino

Rodolfo R Rodriquez

A level sensor of a fluid transfer mechanism for determining when the bottom tip of a fluid aspirating probe touches or contacts the top surface of a sample fluid. The level sensor senses the contact capacitively by grounding one plate of a capacitor through the sample fluid and fluid aspirating probe. One capacitor plate is formed of an electrode biased against the bottom of a rotatable supply tray and positioned under a sample containing cavity in the tray. The other capacitor plate is formed by the bottom surface of the sample fluid in the supply cavity, and the dielectric of the capacitor is formed of the supply tray material. An AC signal is applied to the electrode and the probe is grounded. The change in voltage occurring in the AC signal at the electrode when the probe touches the top surface of the sample fluid it is sensed to provide the touch signal.

Level sensor apparatus and method

An optical timing and A/D conversion method and apparatus for converting analog signals obtained by movement of a plurality of reaction vessels relative to one or more beams of light from analog to digital signals. The sample signals are obtained each time a reaction vessel passes through a beam of light. The converted digital signals indicate the absorbance of the respective vessels and their contents. Each of the reaction vessels or cuvettes has translucent wall portions providing a radiation path therethrough for the light beams which may be monitored by photometer means in a chemical reaction analyzer. The vessels are repeatedly passed through the light beams of the photometer means as chemical reactions take place therein, the purpose being to monitor the changes in the reaction of the fluids therein by measuring the changes in the absorbance of the vessel and fluids. The sample interval of the analog signal is repeatable for each vessel for each light beam and may be shifted to select the best portion of the analog signal generated as the vessel passes through the particular light beam. The A/D conversion also may eliminate the dark sample or noise error between the light beams and the reaction vessels and may eliminate the variations in the sample signals caused by changes in the rate of relative movement between the beams and vessels and changes in the velocity of the rotating beam.

Optical timing and A/D conversion method and apparatus

The characteristics of a sample body fluid are determined in a chemical analyzer by sensing the transmittance of light by the sample fluid and reagents during a reaction period. A beam of light is directed onto a cuvette containing the sample body fluid and reagent. A portion of the light is absorbed by the cuvette, the sample fluid and reagent. The remainder of the light is transmitted to a sensor which provides an analog electrical transmittance signal proportional thereto. The analog signal is logarithmically amplified, and is applied to a peak detector. A structure adjacent the cuvette provides a strobe signal such that the analog signal always has a peak amplitude during the strobe signal. The peak detector senses the peak amplitude of the analog signal during the strobe signal and the peak amplitude is converted to a digital value representing absorbance.

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North Miami Beach, FL, United States of America

Steven N Kolber