MEASUREMENT OF PARTICLE-SIZE AND ELECTROSTATIC CHARGE-DISTRIBUTIONS ON TONERS USING E-SPART ANALYZER

Electrostatic properties and particle-size distribution of toner particles play an important role in electrophotography. Performance characteristics of a laser-based instrument called the electrical-single particle aerodynamic relaxation time (E-SPART) analyzer for measuring aerodynamic size and electrostatic charge distribution of particles in real time and on a single-particle basis are described. Applications of this analyzer along with experimental data of the characterization of different toners for their size and charge distributions are presented, including operational principles and methods of data acquisition. Size distribution ranged from 2.0 to 20.0-mu-m in aerodynamic diameter, and the charge-to-mass distribution ranged from 0 to +/- 20-mu-C/g. The method is noncontact and provides both magnitude and polarity of electrostatic charge on an individual particle basis. The aerodynamic diameter and charge are measured simultaneously at an average count rate of approximately 100 particles/s.