| 摘要 |
PURPOSE:The titled apparatus which is allowed to detect the presence of an ink drop jet at a high accuracy with a high S/N ratio by checking an induced current generated when a charged ink drop is flying toward an ink drop attaching body. CONSTITUTION:A charged voltage Vc is applied between a nozzle 1 and a charging electrode 15 to fly a conductive ink in a charged ink drop and a charge in the opposite polarity is induced in an ink drop attaching body 16. The induced current flows through a resistance 20 of a detection circuit 18 to generate a negative voltage in a parallel circut comprising the resistance 20 and a capacitor causing a gradual drop in the voltage. Then, the negative voltage is inputted into a voltage amplification circuit 23 through a buffer circuit 22 to amplify and compared with a reference voltage 19 by a comparator 24 and when it exceeds the reference voltage, a detection signal is outputted to an upper equipment. |
