Ink jet recording method and apparatus

Claim 2

In a method of printing on a document wherein ink is supplied to a nozzle under pressure and varicosities are produced in the ink stream to cause the stream to break up into uniformly sized and spaced drops in the region of a charging electrode which is energized to charge selected ones of said drops for causing them to deflect while passing through an electric field, the improvement which comprises; energizing said charging electrode with signal voltages of one polarity at spaced time intervals to charge spaced ink drops to deflect them onto said document in a predetermined pattern, and energizing said charging electrode at intervening time intervals with a base voltage of the opposite polarity and sufficient value to cause selected ones of said signal voltage charged drops to merge in flight before being deflected to print on said document.

Claim 3

The invention as defined in claim 1 characterized by every other ink drop being charged by a signal voltage and the intervening drops being charged by a uniform base voltage so that pairs of adjacent drops merge in flight to form larger drops with a resultant increase in the density of the printing.

Claim 4

The invention as defined in claim 1 characterized by every fourth drop being charged by a signal voltage, and the two drops on either side of each such fourth drop being charged with a base voltage of the opposite polarity so that three successive ink drops combine in flight and form a larger drop with a resultant increase in print density.

Claim 5

In an ink drop printer having a nozzle for producing a stream of ink drops, transducer means associated with said nozzle for producing varicosities in the ink stream to insure uniform drop formation, clock means for applying timed pulses to said transducer means, a charging electrode positioned in predetermined spaced relation with said nozzle for charging selected ones of said ink drops, deflection means providing a field beyond said charging electrode to deflect said charged ink drops, and means connecting said charging electrode to a source of data signals, the improvement comprising circuit means connected between said charging electrode and said source of data signals and said clock means for selectively charging selected spaced ink drops with predetermined data signals of one polarity and intervening drops with a uniform base voltage of the opposite polarity to cause selected ones of said data signal charged ink drops and said base voltage charged ink drops and said base voltage charged ink drops to combine in flight before being deflected by said deflecting field.

Claim 6

In an ink drop printer having a nozzle for producing a stream of ink drops, transducer means associated with said nozzle for producing varicosities in the ink stream to insure uniform drop formation, clock means for applying timed pulses to said transducer means, a charging electrode positioned in predetermined spaced relation with said nozzle for charging selected ones of said ink drops, deflection means providing a field beyond said charging electrode to deflect said charged ink drops, and means connecting said charging electrode to a source of data signals, the improvement comprising circuit means connected between said charging electrode and said source of data signals and said clock means for selectively charging selected spaced ink drops with predetermined data signals of one polarity and intervening drops with a uniform base voltage of the opposite polarity to cause selected ones of said data signal charged ink drops and said base voltage charged ink drops and said base voltage charged ink drops to combine in flight before being deflected by said deflecting field.

Claim 7

The invention as defined in claim 4 characterized by said circuit means including logic means and a differential amplifier connected between the charging electrode and the data source and said clock means operable to selectively gate inputs to said differential amplifier from said data source and said clock means.

Claim 8

The invention as defined in claim 5 characterized by said circuit means including gating means connecting said data source and a source of base voltage to said differential amplifier.

Claim 9

The invention as defined in claim 6 characterized by said logic means functioning in accordance with the following truth table: