Patent ID: 7242473

Claim:
A particle size distribution analyzer comprising: a sample housing which stores a sample powder; a vibration actuator which vibrates the sample housing to thereby drop the sample powder from the sample housing; a light source which irradiates the dropping sample powder with light; a light detector which detects intensity of scattered light and/or transmitted light generated by the irradiation of the sample powder with the light and then outputs the intensity as a light intensity signal; and a data processing system which, based on the light intensity, controls the vibration actuator and also calculates particle size distribution of the sample powder, wherein the data processing system comprises: an integral part which integrates the light intensity indicating the light intensity signal by two mutually different times and outputs each of the integrated values; an actuator control part which generates and outputs a control signal for the vibration actuator so that one of the integrated values of light intensity outputted from the integral part becomes closer to a set value previously defined; and a particle size distribution calculation part which calculates the particle size distribution of the sample powder based on another of the integrated values of light intensity outputted from the integral part.