Patent ID: 6260955
Filing Date: 2001-07-17
Classification: B41J,G03G

Abstract:
A printing apparatus comprising:heat treatment means;a rotatable feeder roll chargeable to a predetermined first potential;a support roll chargeable to a predetermined second potential; anda matrix in the form of a printing circuit, said matrix having supply apertures, each supply aperture having a first inner diameter and being surrounded by an electrically conducting control ring configured to be charged to a predetermined third potential and having a second inner diameter, said third potential being selected to control corresponding supply apertures between an open and closed state, said open state being achieved when said third potential is higher than said first potential and lower than said second potential, and said closed state being achieved when said third potential is lower than said first potential, said second inner diameter of the control ring being at least equal to the first inner diameter of the supply aperture, said matrix and said electrically conducting control rings being covered on upper surfaces and aperture edges with an electrically insulating layer;wherein said feeder roll, said support roll and said matrix are configured to transfer a dry powder from said feeder roll through said supply apertures of the matrix to an object to be printed which is conveyed over said support roll, said powder deposited on the object being fixed by said heat treatment means.