Ink jet recording apparatus and ink jet recording method

An ink jet recording apparatus comprising:

• an ink jet head which forms an image on a recording medium in response to a drive signal applied to multiple piezoelectric elements, the drive signal causing multiple pressure chambers corresponding to the multiple piezoelectric elements to expand or to contract in volume and causing ink in the multiple pressure chambers to be discharged from multiple nozzles;
• and
• a drive circuit which generates a drive signal for discharging multiple liquid droplets to one pixel for combining the multiple liquid droplets together and applies the drive signal to each of the multiple piezoelectric elements of the ink jet head,
• wherein the drive signal includes multiple discharge pulses which make velocities of tips of respective liquid columns substantially same after a predetermined time from starting of ink discharge from the nozzles,
• wherein, in the drive signal, a last discharge pulse of the multiple discharge pulses is included in a satellite reducing pulse,
• wherein, the drive signal includes the multiple discharge pulses and the satellite reducing pulse,
• wherein a pulse width of the respective multiple discharge pulses is 1.0 to 1.3 times of AL,
• wherein a standby time between one of the multiple discharge pulses and another of the multiple discharge pulses is 0.3 to 0.5 times of AL,
• wherein a standby time is longer than or has a same length as a preceding standby time, and
• wherein a last discharge pulse of the multiple discharge pulses includes a satellite reducing pulse.

An ink jet recording method comprising:

• forming an image on a recording medium in response to a drive signal applied to multiple piezoelectric elements, causing multiple pressure chambers corresponding to the multiple piezoelectric elements to expand or to contract in volume and causing ink in the multiple pressure chambers to be discharged from multiple nozzles;
• and generating a drive signal for discharging multiple liquid droplets to one pixel for combining the multiple liquid droplets together and applying the drive signal to each of the multiple piezoelectric elements of the ink jet head,
• wherein the drive signal includes multiple discharge pulses which make velocities of tips of respective liquid columns substantially same after a predetermined time from starting of ink discharge from the nozzles;
• wherein, in the drive signal, a last discharge pulse of the multiple discharge pulses is included in a satellite reducing pulse;
• wherein, the satellite reducing pulse sequentially includes:
• a first expansion pulse which starts from a reference voltage and causes the multiple pressure chambers to expand in volume;
• a first contraction pulse which causes the multiple pressure chambers to contract in volume to discharge ink from the multiple nozzles;
• a second expansion pulse which causes the multiple pressure chambers to expand in volume;
• and
• a second contraction pulse which causes the multiple pressure chambers to contract in volume,
• wherein a top voltage of the first contraction pulse is higher than the reference voltage,
• wherein the second expansion pulse is applied within 1 AL from starting of the first contraction pulse, and
• wherein the second contraction pulse is applied within 1 AL from starting of the second expansion pulse.

An ink jet recording method comprising:

• forming an image on a recording medium in response to a drive signal applied to multiple piezoelectric elements, causing multiple pressure chambers corresponding to the multiple piezoelectric elements to expand or to contract in volume and causing ink in the multiple pressure chambers to be discharged from multiple nozzles;
• and generating a drive signal for discharging multiple liquid droplets to one pixel for combining the multiple liquid droplets together and applying the drive signal to each of the multiple piezoelectric elements of the ink jet head,
• wherein the drive signal includes multiple discharge pulses which make velocities of tips of respective liquid columns substantially same after a predetermined time from starting of ink discharge from the nozzles,
• wherein, in the drive signal, a last discharge pulse of the multiple discharge pulses is included in a satellite reducing pulse,
• wherein, the drive signal includes the multiple discharge pulses and the satellite reducing pulse,
• wherein a pulse width of the respective multiple discharge pulses is 1.0 to 1.3 times of AL,
• wherein a standby time between one of the multiple discharge pulses and another of the multiple discharge pulses is 0.3 to 0.5 times of AL,
• wherein a standby time is longer than or has a same length as a preceding standby time, and
• wherein a last discharge pulse of the multiple discharge pulses includes a satellite reducing pulse.