Abstract: A method and device for optically counting small particles, like grains of seed and fertilizer and other materials employed in agriculture. The particles to be counted travel past a test field, interrupting as they do so a beam of light between a light emitter and a light detector. To make it possible to detect even several particles in the test field at the same time and to make the counting generally more precise, individual points where the path of a beam of light is interrupted by particles passing through the grid are detected in sequential scanning cycles by beams of light that create an optical grid and are retained in the form of information describing one or more particles, information describing the particles and obtained in different scanning cycles are compared, and counting signals that correspond to the number of individual particles passing through are derived from the variations in the interrupting points determined during the comparison.

Abstract: Method of counting particles of seed, fertilizer, and other materials employed in agriculture acoustically. The particles to be counted are conveyed against an impact plate in such a way as to start it oscillating, generating electric signals that are processed to determine the number of particles. In order to count the exact number of individual particles passing a test point with relatively high precision and by acoustical means, at least one definite oscillation amplitude that is characteristic of the impact of one particle is determined and stored and a comparable actual oscillation amplitude is determined as the particles strike against the impact plate, is compared with the stored oscillation amplitude, and, if it is shorter than the characteristic amplitude, one particle counted, or, if it is higher than the characteristic amplitude, the inference made that another particle has struck the plate.