Driving method of piezoelectric elements, ink-jet head, and ink-jet printer

An ink-jet head, comprising:

• a multiplicity of ink pressure chambers with partition walls, portion of the partition walls making up piezoelectric elements,
• said ink-jet head applying a driving voltage to the piezoelectric elements to cause the piezoelectric elements to deform, so as to eject ink that is stored in the ink pressure chambers,
• said ink-jet head setting at least one of Tr and Tf to be not less than {fraction (1/20)} of Ti, where Tr and Tf are a rise time and a fall time, respectively, of the driving voltage that is applied to the piezoelectric elements, and Ti is a period of natural oscillation of an oscillating system in the ink pressure chambers, and
• said ink-jet head setting at least one of the Tr and Tf to be not more than ⅓ of the Ti.

An ink-jet printer, comprising:

• an ink-jet head that includes a multiplicity of ink pressure chambers with partition walls, portions of the partition walls making up piezoelectric elements,
• said ink-jet head applying a driving voltage to the piezoelectric elements to cause the piezoelectric elements to deform, so as to eject ink that is stored in the ink pressure chambers,
• said ink-jet printer setting at least one of Tr and Tf to be not less than {fraction (1/20)} of Ti, where Tr and Tf are a rise time and a fall time, respectively, of the driving voltage that is applied to the piezoelectric elements, and Ti is a period of natural oscillation of an oscillating system in the ink pressure chambers, and
• said ink-jet printer setting at least one of the Tr and Tf to be not more than ⅓ of the Ti.

An ink-jet head, comprising:

• a multiplicity of ink pressure chambers with partition walls, portion of the partition walls making up piezoelectric elements,
• said ink-jet head applying a driving voltage to the piezoelectric elements to cause the piezoelectric elements to deform, so as to eject ink that is stored in the ink pressure chambers,
• said ink-jet head setting at least one of Tr and Tf to be not less than {fraction (1/20)} of Ti, where Tr and Tf are a rise time and a fall time, respectively, of the driving voltage that is applied to the piezoelectric elements, and Ti is a period of natural oscillation of an oscillating system in the ink pressure chambers, and
• said ink-jet head setting a sustained time Tv of the driving voltage to satisfy Tv≈(Ti−Tr)/2.

An ink-jet printer, comprising:

• an ink-jet head that includes a multiplicity of ink pressure chambers with partition walls, portions of the partition walls making up piezoelectric elements,
• said ink-jet head applying a driving voltage to the piezoelectric elements to cause the piezoelectric elements to deform, so as to eject ink that is stored in the ink pressure chambers,
• said ink-jet printer setting at least one of Tr and Tf to be not less than {fraction (1/20)} of Ti, where Tr and Tf are a rise time and a fall time, respectively, of the driving voltage that is applied to the piezoelectric elements, and Ti is a period of natural oscillation of an oscillating system in the ink pressure chambers, and
• said ink-jet printer setting a sustained time Tv of the driving voltage to satisfy Tv≈(Ti−Tr)/2.