MEANS FOR SENSING WHICH DETECTS SHORT-CIRCUITING IN INK WHICH IS NOT DESIRABLE

PROBLEM TO BE SOLVED: To detect short-circuiting on the charging plate of an inkjet print head. SOLUTION: Detecting means is the detecting means for detecting the short-circuiting by undesired ink charged on the charging plate 18 of the inkjet print head. The detecting means equips first cross section detecting means 40, and second cross section detecting means 42. The first cross section detecting means 40 and the second cross section detecting means 42 are positioned under a plurality of charging electrodes 38 with respect to the advancing direction of a droplet stream, and are positioned on the same plane as the charging plate 18 surface. The detecting means equips an ac detecting means for detecting the short-circuiting by the resistive coupling between the first cross section detecting electrode 40 and the second cross section detecting means 42 by excluding the capacitive coupling from the output signal by discriminating the resistive coupling and the capacitive coupling between the first cross section detecting electrode 40 and the second cross section detecting electrode 42. COPYRIGHT: (C)2009,JPO&INPIT