Patent ID: 7036899

Claim:
A printing apparatus for performing printing using a printhead having a plurality of printing elements, comprising: means for inputting print data; converting means for converting print data to drive data corresponding to the printing elements; transfer means for transferring the drive data to the printhead in a serial format in units of N bits at a time; driving means for driving the printing elements based upon the drive data; counting means for counting M-bits of data transferred first among the drive data in synchronism with transfer of the drive data by said transfer means, where N>M; detecting means for detecting an increase in the value of a count obtained by said counting means; and voltage generating means for outputting a voltage that drives the printing elements; wherein if said detecting means has detected an increase in the value of the count, said voltage generating means raises the output voltage before said driving means performs drive based upon drive data transferred next, wherein said voltage generating means comprises an error amplifier for outputting a control signal in accordance with an error between a reference voltage and an input voltage, and if said detecting means has detected an increase in the value of the count, the value of the reference voltage is changed, and wherein said voltage generating means differentiates a signal that is output in accordance with detection by said detection means and adds a voltage, which has been obtained via a time-constant circuit and a current adding circuit, to the reference voltage.