APPARATUS AND METHOD FOR MEASUREMENT OF THE RATIO OF TONER PARTICLE ELECTROSTATIC CHARGE TO TONER PARTICLE MASS IN ELECTROSTATOGRAPHIC DEVICES

• Main Author: BERGMAN, NORMAN J
• Format: Patent
• Language: English; French
• Published: 02.12.1980
• Subjects: CINEMATOGRAPHY; ELECTROGRAPHY; ELECTROPHOTOGRAPHY; HOLOGRAPHY; MAGNETOGRAPHY; PHOTOGRAPHY; PHYSICS

APPARATUS AND METHOD FOR MEASUREMENT OF THE RATIO OF TONER PARTICLE ELECTROSTATIC CHARGE TO TONER PARTICLE MASS IN ELECTROSTATOGRAPHIC DEVICES Apparatus and method for measurement of the ratio of the triboelectric toner particle charge to the toner particle mass in electrostatographic apparatus. The ratio of the toner particle charge to the toner particle mass is determined by combining a measurement of the difference between the electrostatic photoreceptor potential in the presence and in the absence of charged toner particles with a measurement of a difference in optical reflectance in the presence and in the absence of charged toner particles. The measurement of the difference in the electrostatic potential of the photoreceptor provides a quantity proportional to the toner particle charge per unit area. The measurement of the difference in optical reflectance provides a quantity related to the toner mass per unit area, a quantity that is linear for low particle densities. Combining the two difference measurements provides a quantity proportional to the toner charge per toner mass. The ratio of toner particle electrostatic charge to toner particle mass can be utilized to preserve the quality of an electrostatographically reproduced image. Apparatus is disclosed for deriving a signal related to the toner charge to toner mass during electrostatographic processing. The derived signal can provide a feed back control signal for maintaining the ratio of the toner particle charge to toner particle mass in an acceptable range, for example, by controlling the ratio of the toner particles and the carrier particles in the developer mixture.