| 摘要 |
An ink jet printing head includes a plurality of pressure chambers having a natural period T2 for propagation of a wave, and a plurality of piezoelectric elements having a natural period T1 for oscillation. T1 and T2 are selected such that T1=nxT2 or T2=nxT1 wherein n is a natural number. The driving voltage for the piezoelectric elements has a rise time T3 selected at T3=mxT2 wherein m is a natural number not lower than two if T1=2xT2, or selected at T3=mxT2 wherein m is a natural number if T2=nxT1. The rise time T3 may be selected at T3=nxT1 in the latter case. Both the rise time T3 and the voltage level V of the driving voltage are selected in a single printing head so that V/T3 is a constant for attaining a gray scale level printing. The rise time T3 thus selected provides stable ink droplets without satellite ink droplets degrading the printing quality.
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