Apparatus for the development of electrostatic images

Claim 1

APPARATUS FOR DEVELOPING A VISUAL IMAGE FROM A LATENT ELECTROSTATIC IMAGE ON THE SURFACE OF AN IMAGE CARRYING MEMBER BY DISTRIBUTING ELECTROSCOPIC POWDER THEREON IN A DENSITY PATTERN CORRESPONDING TO THE CHARGED DISTRIBUTION IN SAID IMAGE COMPRISING A FIRST ROLLER MEMBER HAVING A DEVELOPER SURFACE, SAID DEVELOPER SURFACE BEING UNIFORMLY ELECTRISTATICALLY SATURABLE BY A PREDETERMINED QUANTITY OF SAID ELECTROSCOPIC POWDER, SAID FIRST ROLLER MEMBER BEING POSITIONED WITH SAID DEVELOPER SURFACE BEARING AGAINST SAID IMAGE BEARING SURFACE OF SAID CARRIER, A SECOND ROLLER MEMBER HAVING A TRANSFER SURFACE CAPABLE OF RETAINING OVER SUBSTANTIALLY THE ENTIRE SURFACE THEREOF BY TRIBOELECTRIC ATTRACTION AT LEAST SAID PREDETERMINED QUANTITY OF ELECTROSCOPIC POWDER, SAID SECOND ROLLER BEING POSITIONED WITH SAID TRANSFER SURFACE THEREOF BEARING AGAINST SAID DEVELOPER SURFACE, SAID DEVELOPER SURFACE, SAID TRANSFER SURFACE AND SAID ELECTROSCOPIC POWDER BEING DIFFERENTIALLY TRIBOELETRICALLY RELATED WHEREBY SAID POWER TRANSFERS TO SAID DEVELOPER SURFACE ON CONTACT THEREWITH WHEN SAID DEVELOPER SURFACE IS ELECTROSTATICALLY UNSATURATED AND IS RETAINED ON SAID TRANSFER SURFACE WHEN SAID DEVELOPER SURFACE IS ELECTROSTATICALLY SATURATED, MEANS FOR DISTRIBUTING ELECTROSCOPIC POWDER OVER THE ENTIRE AREA OF SAID TRANSFER SURFACE IN AN AMOUNT OF AT LEST SAID PREDETERMINED QUANTITY, MEANS FOR MOVING SAID IMAGE BEARING MEMBER, SAID DEVELOPER MEMBER AND SAID TRANSFER MEMBER AT MUTUALLY INTERRELATED SPEEDS WHEREBY THE RELATIVE VELOCITIES OF SAID IMAGE BEARIGN SURFACE, SAID TRANSFER SURFACE AND SAID DEVELOPER SURFACE ARE ZERO DURING CONTACT.