Coulter Electronics, Inc.

Ermi Roos

Wallace H Coulter

Ian D Gilbert

Michael T Halloran

Robert L Talbert

A debris detector for a particle counter, such as a blood cell counter, of the COULTER (R) type. When a particle, or transient debris, passes through the sensing orifice of the particle detector, a voltage pulse occurs; whereas, when debris lodges in or against the orifice of the particle detector, a d.c. voltage shift occurs. The voltage at the orifice is capacitively coupled to an amplifier and the output of the amplifier is integrated. The capacitor coupling the orifice voltage to the amplifier causes an undershoot voltage at the trailing edge of each particle or transient debris pulse, such that a zero average voltage is applied to and, hence, from the amplifier for each voltage pulse. The integrated voltage is applied to a voltage comparator to provide an output signal therefrom whenever the integrated voltage exceeds a reference voltage. The comparator output signal is provided to a delay circuit having a delay related to the time required for a particle to pass through the COULTER detector orifice. If the comparator signal remains after the delay time, a debris alarm signal is provided. This occurs only if a d.c. voltage shift had occurred, since there is no trailing edge, and hence no undershoot to return the integrated voltage to zero prior to the delay time.

Lodged debris detector for a particle analyzer

An amplifier circuit having an input circuit of resistance and capacitance which is a.c. coupled to a source of pulses, and a feedback circuit of resistance and capacitance. The RC time constants of the input and the feedback circuits are made to be approximately equal at the time of pulse input in order to insure an output pulse flat base line without undershoot or overshoot.

Pulse amplifying system

A centrifugal feeder includes a cylindrical feeder disc having an upwardly inclined uniform surface which is designed to expel particles placed thereon in a predetermined fashion by centrifugal force. The upwardly inclined surface of the disc may be designed to have a first predetermined expulsion rate which is the initial speed at which the disc must be rotated to expel any of the particles from the surface thereof. The disc also may be designed to have a final expulsion rate at which all particles placed on the surface thereof are expelled. The disc is rotated at a controlled rate of speed and at a controlled rate of change of speed to expel the particles in the manner desired in a linear or non linear fashion. The feed or expulsion rate of the particles is determined by the design of the disc and the rotation speed of the disc and essentially is independent of the size and density of the particles and the viscosity of the surrounding fluid in which the disc is rotated.

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Hialeah, FL, United States of America

Ermi Roos