Patent ID: 8777349

Claim:
An image forming apparatus comprising: a recording head having a nozzle to eject a droplet of a liquid, a liquid chamber communicating with the nozzle, and a pressure generator to generate a pressure to pressurize the liquid in the liquid chamber; and a driving waveform generator connected to the pressure generator to generate and output a driving waveform including a plurality of driving pulses per driving cycle to eject the droplet from the nozzle, a last one of the plurality of driving pulses including a first expansion waveform element to expand the liquid chamber, a first retaining waveform element to retain a first expanded state of the liquid chamber created by the first expansion waveform element, a first contraction waveform element to contract the liquid chamber from the first expanded state of the liquid chamber retained by the first contraction waveform element to eject the droplet from the nozzle, a second retaining waveform element to retain a first contracted state of the liquid chamber created by the first contraction waveform element, a second contraction waveform element to further contract the liquid chamber from the first contracted state of the liquid chamber retained by the second retaining waveform element, a third retaining waveform element to retain a second contracted state of the liquid chamber created by the second contraction waveform element, and a second expansion waveform element to expand the liquid chamber from the second contracted state retained by the third retaining waveform element to a state prior to application of the first expansion waveform element, the first contraction waveform element having a potential difference greater than a potential difference of the first expansion waveform element, the second contraction waveform element having a time period longer than a time period of the first contraction waveform element.