Patent ID: 8005409

Claim:
A development device that develops an electrostatic latent image recorded on a photoconductive surface, the development device comprising: an open-ended housing to accommodate toner for application to the photoconductive surface through an end opening thereof; a rotatable developer roller having an outer circumferential surface thereof partially accommodated within the housing and partially facing the photoconductive surface through the end opening to deliver the toner from within the housing to a development zone defined between the roller surface and the photoconductive surface; an array of multiple primary electrodes aligned parallel with each other on and extending longitudinally along the roller surface; a voltage source to apply a periodic pulse voltage to at least a subset of the primary electrodes to generate an oscillating primary electric field under which the toner moves back and forth between neighboring primary electrodes and consequently jumps across the development zone to adhere to the electrostatic latent image; a sealing member to seal clearance between the roller surface and an edge of the end opening; and a secondary electrode facing at least a portion of the roller surface closest to the sealing member to generate, when energized, a secondary electric field to force the toner toward the roller surface to counteract an electrostatic force of the primary electric field repelling the toner from the roller surface.