Patent ID: 6454377
Filing Date: 2002-09-24
Classification: B41J

Abstract:
A driving circuit for ink jet printing head which comprises at least one nozzle and at least one pressure producing chamber and which, when printing, applies a driving waveform signal to at least one piezoelectric actuator provided at a position corresponding to said pressure producing chamber to rapidly change a volume of said pressure producing chamber filled with ink, thereby ejecting ink droplets from said nozzle, further comprising:storage means for storing driving waveform information for each diameter of said ink droplets; a plurality of waveform control means which is provided for each diameter of said ink droplets and which reads out and then sequentially outputs corresponding said driving waveform information; a plurality of waveform generating means which is provided for each diameter of said ink droplets, for generating respectively corresponding driving waveform signals, each of which has a trapezoidal waveform or a triangular waveform, by converting driving waveform information provided sequentially from said waveform control means into analog information and then by conducting an integration operation on said converted analog information; driving means which selects one driving waveform signal of a plurality of driving waveform signals output from said plurality of waveform generating means and applies said one driving waveform signal to said piezoelectric actuator; and wherein each waveform generating means comprises a digital/analog converter which converts said voltage information or said current information into an analog signal, an integrator which comprises an operational amplifier and an integrating capacitor to perform integration operations on said analog signal, a negative feed-back unit which gives a negative feed-back to said operational amplifier so as to hold an output voltage of said waveform generating means to a zero potential before stating of and after termination of printing and to a prescribed bias potential which provides a reference of contraction and expansion of said piezoelectric actuator at a time point of not printing during printing operations, and a negative feed-back cut-off unit which cuts off said negative feed-back to ground a positive input terminal of said operational amplifier.