Patent ID: 7733487

Claim:
A particle counting method, comprising: a. radiating a fluid sample with a laser light; b. causing the laser light to hit a particle in the fluid sample to produce scattered light; c. detecting scattered light by a photoelectric conversion element; d. defining at least one particle size range; e. sequentially comparing a maximum value of the output of the photoelectric conversion element to a threshold preset for each particle size range to thereby count the number of particles for each particle size range; f. comparing a sample value of the output of the photoelectric conversion element to a threshold of the minimum particle size; g. starting a timer of a predetermined time when the magnitude relation between the sample value and the threshold of the minimum particle size changes in step (f); and h. incrementing by one the number of particles of a particle size range corresponding to the maximum sample value among the sample values collected up until the time that the timer is terminated and the sample value becomes smaller than the minimum particle size threshold.