Traveling wave actuated segmented charging electrode for an ink jet printer

Claim 3

A method as set forth in claim 1 wherein the steps of forming said traveling wave comprises supplying an appropriate signal to a commutating delay circuit means and applying the output of said commutating circuit means to a spaced series of charging electrodes located adjacent to the ink jet stream in an electrostatic charging relationship therewith.

Claim 4

In an ink jet recording system including an ink supply, a nozzle, means for projecting a high pressure ink stream from said nozzle at a predetermined velocity which breaks up into droplets downstream therefrom at a fixed predetermined rate, means for applying an electrical charge to individual droplets as they break off from said stream, means for deflecting said droplets and a recording medium on which said droplets impinge to produce a visible record, the improvement in said charge application means which comprises: a multi-segment charging electrode, said segments being spaced along the axis of said stream beginning at a point prior to earliest expected droplet break-off and extending to a point beyond latest expected droplet break-off; a tapped delay circuit having a signal input end; one of said charging segments connected to each tap; means for introducing charging pulses into one end of said delay circuit whereby a traveling wave charging signal appears on the segments of said charging electron; said delay circuit having an inter-tap delay equal to the transit time of a droplet making up said stream to move from one segment to the next segment whereby a traveling charging wave is produced on said charging electrode traveling at substantially the same velocity as the ink stream.

Claim 5

In an ink jet recording system including an ink supply, a nozzle, means for projecting a high pressure ink stream from said nozzle at a predetermined velocity which breaks up into droplets downstream therefrom at a fixed predetermined rate, means for applying an electrical charge to individual droplets as they break off from said stream, means for deflecting said droplets and a recording medium on which said droplets impinge to produce a visible record, the improvement in said charge application means which comprises: a multi-segment charging electrode, said segments being spaced along the axis of said stream beginning at a point prior to earliest expected droplet break-off and extending to a point beyond latest expected droplet break-off; a tapped delay circuit having a signal input end; one of said charging segments connected to each tap; means for introducing charging pulses into one end of said delay circuit whereby a traveling wave charging signal appears on the segments of said charging electron; said delay circuit having an inter-tap delay equal to the transit time of a droplet making up said stream to move from one segment to the next segment whereby a traveling charging wave is produced on said charging electrode traveling at substantially the same velocity as the ink stream.

Claim 6

An ink jet recording system as set forth in claim 3 wherein said tapped delay circuit comprises a passive lumped parameter delay line having a signal input means at one end and a signal terminating means at the other, said tap points being equally spaced in time wherein the tap closest to the signal input end is connected to the charging electrode segment closest to said nozzle and wherein adjacent tap points are connected to subsequent charging electrode signals downstream from said first segment.

Claim 7

An improved ink jet recording system as set forth in claim 3 wherein said delay circuitry comprises an active multi-stage shift register having as many stages as there are segments of said charging electrode, each stage having an output line connected to one of said charging electrode segments, clock means for advancing an input signal applied to the input of said delay circuitry between said stages, the frequency of said clock being chosen to advance an input signal applied at one end of said delay circuit through said delay circuit at the same velocity as an ink droplet in said stream passing through said charging electrode structure.

Claim 8

An improved ink jet recording system as set forth in claim 5 wherein each stage of said shift register comprises a single binary storage element which may store a binary 1 or a 0 and including means for serially applying binary input data to said delay circuitry in binary form.

Claim 9

An improved ink jet recording system as set forth in claim 5 wherein each stage of said shift register comprises a bucket-brigade analog storage element for storing an analog signal and means for supplying a serial string of analog pulses to the input of said delay circuit.

Claim 10

An improved ink jet recording system as set forth in claim 5 wherein each stage of said shift register comprises plural bit storage means for storing a digitally encoded bit group, representing an analog deflection signal to be applied to said charging electrode structure, digital-to-analog converter means for converting said digital bit group to an anaLog charging signal on said elements of the charging electrode, means for supplying a series of digitally encoded analog values to the input of said shift register representing analog signals to be applied to sequential ink droplets in said system.

Claim 11

An ink jet recording system as set forth in claim 8 wherein said digital-to-analog converter means comprises an electronic circuit directly connected to the output of each multi-bit shift register stage and which decodes the digital information into an analog charging signal.

Claim 12

An ink jet recording system as set forth in claim 8 wherein said digital-to-analog converter means comprises a capacitor connected between each bit storage element of the shift register stage and the associated charging electrode segment the size of each capacitor being such that it passes a signal representative of the digital weighting of the digit stored by its associated shift register element and wherein any binary 1 or 0 in any shift register element is represented by a signal of a predetermined magnitude.

Claim 13

An ink jet recording system as set forth in claim 8 wherein said digital-to-analog converter means comprises said each segment of said charging electrode being divided into arcuate sections having different capacitance with respect to the ink stream and being of different size, each section connected to each bit storage element of said shift register the size of each section being such that if a uniform signal is placed on each section the charging effect will be proportional to the digital weighting of the digit element of the shift register stage to which it is connected.