Head for electrically printing an image

Claim 1

A bar for printing an image on a sensitive paper by scanning the paper along successive lines, comprising a plurality of printing styli aligned along the length of the scan line, and comprising n square matrices for addressing the styli, the matrices being formed by a first network of electrically conductive tapes which are insulated from one another and are divided into n identical sets of conductors and each of which has one end connected to a respective stylus, and by a second network of electrically conductive tapes perpendicular to the first network and having as many tapes as there are conductive tapes in each set of the first network and selectively connected to the conductive tape of the first network to form the said n matrices, characterized in that the first network and the second network of conductive tapes (1, 7) are formed respectively on a first insulative plate (3,4) and on a second insulative plate (6), and are disposed on the interior faces of the plates when assembled together and are isolated from each other at the intersections between conductive tapes except for the selective connections for forming each of the said matrices and in that for each matrix (21): the conductive tapes of the first network (1), referred to as the columns of the said matrix, are fed from a first feed terminal (17) attributed to the said matrix, via respective resistances (R) each of which is formed by a layer of resistive material (12) deposited on one of the plates and connecting each of the columns of the matrix to a common conductive strip (13) formed on the other plate and insulated from the tapes of the said other plate and electrically connected to the said first terminal, the conductive tapes of the second network (7), referred to as the rows of each matrix, are individually controlled from respective second feed terminals (14) and are selectively connected to the columns via diodes (D) each formed by a pellet of semi-conductive material (11) which is mounted on one of the two plates defining the row and the column in question at their intersection.