A drive device for an ink jet type printing head which makes it possible to jet ink droplets having different sizes from the same nozzle, and with which the resultant image is high in picture quality and in gradation, and the printing operation is achieved at high speed. The drive device includes a drive...http://www.google.com.au/patents/US5980015?utm_source=gb-gplus-sharePatent US5980015 - Ink jet printing head embodiment with drive signal circuit outputting different drive signals each printing period and with selecting circuit applying one of the signals to piezoelectric elements that expand and contract pressure generating chambers
