GB1399496A - Particle analyzing system - Google Patents

Abstract

1399496 Particle analysis COULTER ELECTRONICS Ltd 25 Aug 1972 [30 Aug 1971] 39709/72 Heading G1N [Also in Division G4] Pulses from a particle analysing device are detected, an analogue parameter of each being converted to a digital computer-acceptable code and fed to a digital computer, detection of further pulses being inhibited for a period after each pulse. Pulses (one per particle) from a Coulter particle analyzing device are, in one embodiment, passed via a gate (optionally preceded by noise exclusion circuits) to a sample-and-hold circuit feeding an A/D converter, both being enabled by a peak-detector also converted to the gate output. The converter output causes one of a number of counts stored in the computer to be incremented, the count being selected by the interface according to the size range. A total count can also be kept e.g. in response to a threshold circuit responsive to the output of the particle analyzing device. The computer can control a printer and/ or graph recorder. The gate mentioned is inhibited after each input pulse by an inhibit device controlled by the peak detector, the particle analyzing device and the interface. A second embodiment replaces the sample-and-hold circuit by a linearity improvement circuit, the peak detector being eliminated, the A/D converter replacing the peak detector in its control of the inhibit device and also serving to reset the linearity improvement circuit. This latter circuit integrates each pulse and compares the integral with the instantaneous value, equality stopping the integration, the resulting value representing the volume of the particle and being supplied to the A/D converter.