METHOD FOR MEASURING MEAN PARTICLE SIZE OF PARTICULATE MATERIAL AND METHOD FOR AUTOMATIC CONTROL OF PARTICLE SIZE

PURPOSE:To perform stable measurement of high accuracy by operating the mean particle size of an accumulated particulate material on the basis of the nth-order moment Mn (n=0, 1, 2...) of the power spectrum of the image of said particulate mate rial. CONSTITUTION:A raw material 1 is illuminated by one or more illumination apparatus es arranged at a diagonally upward part and the reflected image thereof is taken by a TV camera 3. Next, the image taken by the camera 3 is inputted to a mean particle size measuring apparatus 4 and the image signal thereof is stored in an image storage device 6. Subsequently, the stored image is sent to a particle extraction circuit 7 on the basis of the order of the operational control circuit 5 and is binary-coded therein in a floating manner to calculate a particle extracted image. Further, the particle extracted image is divided into (m) images in a lateral direction by a power spectrum operation means 8 and the power spectra of signals wherein image signals are averaged in a longitudinal direction are respectively calculated and the mean power spectrum P(u) thereof is operated and outputted. In a mean particle size opera tion circuit 9, two moments different in order are operated from the spectrum P(u) and a mean particle size is outputted.