The invention describes a number of methods and apparatus for shortening the inter-message gap on a continuous inkjet printer. Included is a novel phase testing methodology.

The invention describes a number of methods and apparatus for shortening the inter-message gap on a continuous inkjet printer. Included is a novel phase testing methodology.

A first wiring supplies a first driving signal to one end of a first piezoelectric elements; a second wiring supplies a first voltage to the other end of the first piezoelectric element to allow the first voltage to maintain the other end of the first piezoelectric element to a common electric potential; a third wiring supplies a second driving signal to one end of a second piezoelectric elements; and a fourth wiring supplies a second signal to the other end of the second piezoelectric element to allow the second signal to maintain the other end of the second piezoelectric element to the common electric potential. The second wiring is arranged between the first wiring and the fourth wiring, the fourth wiring is arranged between the second wiring and the third wiring, and the second wiring and the fourth wiring are arranged between the first wiring and the third wiring.

An inkjet printhead includes two groups of interleaved nozzles. First and second sets of drop-formation waveforms are associated with the groups of nozzles to selectively cause portions of a liquid jet to break off into drops. A timing delay device time-shifts the second-group waveforms relative to those associated with the first-group waveforms. A charging-electrode waveform having portions with first and second potentials is provided to a charging electrode. The waveform energies of the second-group waveforms is larger than the waveform energies of the corresponding first-group waveforms so that printing drops break off from the liquid jets while the charging-electrode is at the first potential, and non-printing drops break off from the liquid jets while the charging-electrode is at the second potential.

An inkjet printhead includes two groups of interleaved nozzles. First and second sets of drop-formation waveforms are associated with the groups of nozzles to selectively cause portions of a liquid jet to break off into drops. A timing delay device time-shifts the second-group waveforms relative to those associated with the first-group waveforms. A charging-electrode waveform having portions with first and second potentials is provided to a charging electrode. The waveform energies of the second-group waveforms is larger than the waveform energies of the corresponding first-group waveforms so that printing drops break off from the liquid jets while the charging-electrode is at the first potential, and non-printing drops break off from the liquid jets while the charging-electrode is at the second potential.

An inkjet printhead includes two groups of interleaved nozzles. First and second sets of drop-formation waveforms are associated with the groups of nozzles to selectively cause portions of a liquid jet to break off into drops. A timing delay device time-shifts the second-group waveforms relative to those associated with the first-group waveforms. A charging-electrode waveform having portions with first and second potentials is provided to a charging electrode. The waveform energies of the second-group waveforms is larger than the waveform energies of the corresponding first-group waveforms so that printing drops break off from the liquid jets while the charging-electrode is at the first potential, and non-printing drops break off from the liquid jets while the charging-electrode is at the second potential.

A discharge waveform generating device includes a timing reference generation circuit, a timing adjustment circuit, a waveform pattern generation circuit, and a timing correction circuit. The timing reference generation circuit generates a discharge timing for generating, from image data, a discharge waveform of ink to print the image data, based on a line synchronization signal for synchronizing discharge operations of discharge nozzles to discharge ink. The timing adjustment circuit sets an adjustment value of the discharge timing. The waveform pattern generation circuit generates the waveform from the image data, based on outputs of the timing reference generation circuit and the timing adjustment circuit. The timing correction circuit causes the waveform pattern generation circuit to start generation of the waveform in a condition in which the waveform pattern generation circuit has not finished the generation of the waveform when the timing reference generation circuit receives the line synchronization signal.

A discharge waveform generating device includes a timing reference generation circuit, a timing adjustment circuit, a waveform pattern generation circuit, and a timing correction circuit. The timing reference generation circuit generates a discharge timing for generating, from image data, a discharge waveform of ink to print the image data, based on a line synchronization signal for synchronizing discharge operations of discharge nozzles to discharge ink. The timing adjustment circuit sets an adjustment value of the discharge timing. The waveform pattern generation circuit generates the waveform from the image data, based on outputs of the timing reference generation circuit and the timing adjustment circuit. The timing correction circuit causes the waveform pattern generation circuit to start generation of the waveform in a condition in which the waveform pattern generation circuit has not finished the generation of the waveform when the timing reference generation circuit receives the line synchronization signal.

A continuous inkjet printer (50) has an ink droplet generator (52) and a controller (58) that varies a modulating voltage applied to the ink droplet generator (52) and measures corresponding breakup times of a jet of ink into ink droplets to obtain a portion of a characteristic of breakup time against modulating voltage. The controller (58) obtains a variation range, varies the modulating voltage over the variation range to obtain the portion of the characteristic, calculates a gradient from the portion of the characteristic, compares the gradient with a predetermined gradient and, depending on whether the calculated gradient is less than or greater than the predetermined gradient, generates an adjusted variation range that is displaced in a first sense or a second, opposite sense, respectively, relative to the variation range.

A continuous inkjet printer (50) has an ink droplet generator (52) and a controller (58) that varies a modulating voltage applied to the ink droplet generator (52) and measures corresponding breakup times of a jet of ink into ink droplets to obtain a portion of a characteristic of breakup time against modulating voltage. The controller (58) obtains a variation range, varies the modulating voltage over the variation range to obtain the portion of the characteristic, calculates a gradient from the portion of the characteristic, compares the gradient with a predetermined gradient and, depending on whether the calculated gradient is less than or greater than the predetermined gradient, generates an adjusted variation range that is displaced in a first sense or a second, opposite sense, respectively, relative to the variation range.