Electrophotographic apparatus

Claim 1

Apparatus for use in electrostatically charging the surface of a dielectric element, comprising a corona discharge monofilament wire in the form of a continuous loop running over pulleys, the arc of contact of said wire with each said pulley not exceeding about 180°, means for advancing the wire in one direction along its loop-shaped path, means for connecting said wire to a corona-generating voltage source, and means for causing relative bodily movement between said corona wire and said dielectric element so that said element surface becomes swept by corona discharge from said wire, said loop being formed by knotting together the ends of at least one length of said monofilament wire and each such knot being embedded in an elastically deformable bead which extends onto wire sections on opposite sides of the knot, said bead having a resistance to elastic deformation such as to reduce the sharpness of the bending of the wire on said opposite sides of such knot during its passage around said pulleys, said bead tapering gradually continuously in thickness at both ends thereof, said wire loop advancing means comprising driving means for driving said wire loop via a pulley, said driving means having an energizing circuit causing smooth acceleration and deceleration of said loop at the commencement and termination of its advancement.