Coulter Electronics, Inc.

Millard D Longman, Jr

Walter R Hogg

Wallace H Coulter

Edward N Doty

Stephen K Campbell

In multiple aperture electronic particle detecting apparatus, there are variations in the physical construction of the apertures intended to be identical, as a result of which the signals produced by the identical sized particle, if passed through all of the apertures, will not be identical. Each apparatus in which a multiple aperture arrangement is used requires many adjustments to be made in balancing the apparatus to compensate for the variations in the signals produced. A method and electronic circuit are disclosed which enable simplified balancing of the detecting means of the apparatus without the need for the many adjustments required heretofore. Particles of unknown size in suspension are passed through the apertures and the current supplied to all but one of the apertures is adjusted to render the signals produced of equal amplitude. The detecting means may be balanced by passing particles of a known suspension, which have a known size, through the apertures and adjusting the current supplied to all but one of the apertures to render the signals produced of equal amplitude. It is immaterial whether the particles are monosized or have a moderately broad size distribution.

Method and apparatus for balancing particle detecting signals generated

A method and apparatus for correcting a particle pulse count subject to coincidence error is disclosed wherein particle pulses, developed in response to passage of particles in a particulate system through a sensing zone, are counted for a predetermined period of time. The predetermined period of time is increased or extended in response to each pulse counted by a time increment that is related to a characteristic of the counted pulse, such as the pulse width, duration, or amplitude. The total additional time period allows the counting of additional particle pulses such that the total count at the end of the extended time period is an error corrected count for the number of particles detected in the predetermined time period.

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Hialeah, FL, United States of America

Millard D Longman, Jr