Abstract: A heater power controller for an ink jet printer wherein the output of a comparator making a comparison between a detection signal of the temperature of an ink in a print head of the ink jet printer and a reference signal is chopped by a clock having a predetermined period so as to be converted into a chopper signal, by which the supply of the power to a heating means provided in the head is controlled. A regulating device for regulating the duty ratio of the chopper signal is provided. Each of pulses constituting the chopper signal is made out of phase with a pulse supplied to other pulse-driven load.

Abstract: In an on-demand type ink-jet recording apparatus, which includes an ink chamber and a polarized piezoelectric element coupled to the ink chamber, the piezoelectric element being polarized as a result of application of a voltage of given polarity thereacross, ink droplets are ejected by applying droplet-ejecting pulses of opposite polarity to that used in polarization of the piezoelectric element for ejecting ink droplets from the nozzle for recording on a recording medium. In order to prevent loss of polarization of the piezoelectric element due to the application of the droplet-ejecting pulses, additional polarization-loss-preventing pulses of opposite polarity (same polarity as that used in polarization treatment of the piezoelectric element) are applied at predetermined points of time to the piezoelectric element to prevent loss of polarization thereof.

Abstract: An on-demand-type ink jet recording apparatus and process wherein the droplet size is controlled to effect halftone-gradiation recording. A preceding pulse is applied to the electromechanical transducer prior to the main pulse so as to control the position of the ink meniscus in the nozzle and thereby control droplet size.