Patent ID: 6652057
Filing Date: 2003-11-25
Classification: B41J

Abstract:
A printing apparatus forming an image on a print medium by supplying an electric energy necessary for printing to a plurality of heating resistances of a printhead,said printhead comprising: a switching device for controlling each of the plurality of heating resistances; and a detection resistance for detecting a property corresponding to a resistance property of the heating resistances; said apparatus comprising: a voltage variable circuit for adjusting a power source voltage, applied to the heating resistances, in accordance with the resistance value of the detection resistance so as to apply energy appropriate for printing; and a head driving power source circuit for comparing a first voltage value, generated by dividing a reference voltage by the detection resistance and a resistance provided outside the printhead, with a second voltage value, generated by dividing an output voltage of the head driving power source driving the printhead by a resistance, and controlling an output voltage so as to cancel a difference between the first voltage value and the second voltage value, wherein the GND-side end of the detection resistance provided inside the printhead is connected as a common wiring with a GND wiring transmitting a driving current of the printhead.