Trailing edge dust control

A non-impact, electrostatic printing system comprising:

• an image member to which toner having a first polarity is applied;
• a conductive impression cylinder having an outer periphery;
• means for rotating said impression cylinder about an axis;
• said image member and impression cylinder being positioned with respect to each other to provide a nip, and so that a web of imagable material passes between said image member and said outer periphery of said impression cylinder so that toner from said image member is transferred to the web of material by pressure fixing of the toner at the nip;
• and
• means for applying an electrical potential of said first polarity to said impression cylinder of sufficient intensity so as to substantially prevent back scatter of toner as a result of aerodynamic forces acting between said image member and impression cylinder.

A method of transferring charged toner from an image member to a web of imagable material using an impression cylinder with a nip between the image member and impression cylinder, comprising the steps of:

• (a) applying toner having a first polarity to the image member;
• (b) moving the web of imagable material at a linear speed in excess of about 150 fpm into contact with the image member to effect toner transfer;
• (c) effecting pressure transfer of the toned image from the image member to the paper using the nip between the image member and impression cylinder;
• and
• (d) substantially preventing toner back scatter by applying an electrical bias of said first polarity in the vicinity of the area of contact between the image member and the web so as to impose an electric force field on the toner particles of sufficient intensity to overcome aerodynamic drag forces which would separate the particles from the image member before application to the web.