| 摘要 |
PURPOSE:To detect precisely a charge quantity of ink particles without arranging detection means in an ink particle flying path, by changing the electric field between deflection electrodes during charge detection of ink particles so that the charge of the ink particles may be detected at a charge detection circuit. CONSTITUTION:An integral circuit 8 is composed of a field-effect transistor 8a, an operational amplifier 8b and a condenser 8c for integration, and an output of the integral circuit 8 is applied to one input end of a differential amplifier 8d to be compared with a reference voltage. The differential amplifier 8d produces an output of a high level [1] when the output voltage level has become more than the reference voltage. A phase retrieve control apparatus 23 issues a retrieve signal to cause a transistor 8e to be momentarily on by a timing signal 1 so that the condenser 8e may be discharged, and after a prescribed time issues a timing signal 2 so that when the output of the amplifier 8d is [1], the output of an AND gate AND1 may become [1] to be applied as a suitable charge detection signal to a charge control circuit 20. |
