Improvements in and relating to apparatus for studying the physical properties of particles

摘要

980, 206. Counting and sizing particles. COULTER ELECTRONICS Ltd. Aug. 31, 1962 [Sept. 20, 1961], No. 33604/62. Heading G1N. In an arrangement for counting and sizing particles in a liquid suspension wherein a predetermined volume of the suspension is drawn through a metering aperture to effect, in the presence of particles, a change of impedance between two electrodes 66, 74 spaced one on each side of the aperture, and the predetermined volume is drawn through by a metering device 60 including an insulative conduit 88 through which a conductive fluid 84 flows between a pair of contacts 90, 91 arranged to start and stop the counter when contacted by the conductive fluid as described in Specifications 927,346 and 865,069, an additional contact 92 is included in the conduit, to be engaged by the conductive fluid shortly after contact with the second contact whereby the aperture is short circuited to prevent the flow of current therethrough. The stop contact connections are arranged so that the preamplifier and/or subsequent stages may be described. Earthing of contact 91 by the mercury, drops the potential at the junction of resistor R18 with diode V7 and cuts off valve section V8B. Subsequent contact with contact 92 short circuits the two electrodes 66, 74 and prevents the flow of current through the aperture. Specifications 722,418 and 865,070 also are referred to.