Random Corporation

Randam Electronics, Inc.

William J Dirr, Jr

Thomas E Kimble

William M Stevens

William E Atkinson

Optical components and methods for an I.V. flow detector providing complete coverage of a drip chamber through the use of a single emitter and receiver. The optical components take the light of a single emitter and spread it uniformly across the entire drip chamber. Furthermore, the light is collimated as it passes through the chamber. In addition, the optics collimates the light at some point in its path from the emitter to the drip chamber. Similarly, it collimates the beam of radiation at some point in its path from the drip chamber to the receiver. Further, the optics creates a plane of symmetry for the light path passing through the center of the drip chamber and lies perpendicular to the path of the light. The design specifically takes into account the optical characteristics of the drip chamber itself.

Optical components for an I.V. flow detector

A drop detector for intravenous systems in which an infrared emitter is pulsed at 10 kHz. The pulsed radiation passes through a drip chamber and then to a detector. The detector circuit determines the amplitude modulation of the 10 kHz. carrier frequency. This provides an indication of when the drop falling through the drip chamber has interrupted the light beam. An automatic gain control circuit maintains the output of the detector, on a long time constant basis, at a constant level to eliminate the vagaries of drip chambers with different optical characteristics and the like. When the AGC circuit lacks the ability to maintain the output of the detector circuitry at a constant level, a fault detector provides an alarm to indicate that the circuitry has exceeded its operational range.

Pulsed drop detector for intravenous systems

A method of calibrating a gamma counter that makes two separate measurements over the peak of the standard source of I.sup.129 and a computational technique to obtain the center of that peak. A microcomputer controlling the instrument's operation changes the high voltage on the instrument's photomultiplier (PM) tube to find the setting which generally brings the I.sup.129 peak into the range of the preset pulse height analyzer (PHA) window. Each measurement in the first pass takes a relatively short period of time and looks for the arbitrarily defined end points of the peak. The microcomputer temporarily defines the midpoint of this range as the location of the I.sup.129 peak. In the second pass, the instrument takes longer measurements, for greater accuracy, at six points on either side of the temporary peak. The microcomputer then curve-fits a first line to the logarithms of the counts obtained at the six points on one side of the temporary peak and a second line to the six points on the other side of the peak. The intersection of the two lines then represents the actual center of the I.sup.129 peak. To bring another peak within the PHA's window, the instrument alters the voltage on the PM tube from the I.sup.129 peak just determined.

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Cincinnati, OH, United States of America

William J Dirr, Jr