Method and apparatus for controlling the electrical charging of drops in an ink jet recording apparatus

Claim 3

The method of claim 1, wherein the timing of said electrical pulses and of said drop formation process is controlled by a common signal and said varying is effected by varying the time relationship between said common signal and said electrical pulses.

Claim 4

The method of claim 1 wherein said relative motion causes said ink jet to aim at that record medium during at least one first interval and at a record medium free location during at least one second interval, and wherein said electrical pulses are applied during said at least one second interval.

Claim 9

In an ink jet apparatus which comprises means (21) for supporting a record medium (20), means including a nozzle (12) and an ink conduit (14) for producing at least one ink jet (16) which propagates along a path directed to said supporting means (21) and, and in the course of a drop formation process, disintegrates into a train of drops (18) and a point of drop formation, an electrode system (22) including control electrode means (24) positioned at said point of drop formation, and deflection electrode means (28) extending along said path between said point of drop formation and said supporting means (21), means affecting said drop formation process, said means being responsive to a first control signal, means (34) for generating said first control signal, an ink electrode (30) positioned in said ink conduit, (14), means for producing relative motion between said supporting means (21) and said ink jet, means (40) responsive to said relative motion to produce a position signal (PIXEL) indicating the relative position between said ink jet producing means (12, 14) and said supporting means (21), first means (44, 54) for producing first electrical pulses (PRINT), said means being responsive to a recording control data signal, said position signal and said first control signal, first coupling means (53) for coupling said first electrical pulses to said control electrode means (24), means including delay means (50) for coupling said first electrical pulses across said ink electrode (30) and said control electrode (24), said pulses selectively applying electrical charges to said drops which charges determine the amount of deflection of the drops by said deflection electrode such that the drops are either allowed to proceed to said record medium or are intercepted, a circuit (FIG. 8) for controlling the relative timing of said electrical pulses and said drop formation process, said circuit comprising second means (151) for generating second electrical pulses in response to said first control signal; means (50, 101) for coupling said first control signal (from oscillator 34) t said second pulse generating means (151) second coupling means (152) for coupling said second electrical pulses from said second pulse generating means (151) across said ink electrode (30) and said control electrode (24) means (130, 131) for sensing a current comprised of the electrical charges which are applied to said drops by said second electrical pulses to produce a current signal, means for varying the time relationship between said first and second electrical pulses and said drop formation process in response to a second control signal, means (149) for producing and varying said second control signal and applying said variable second control signal to said time relationship varying means to vary said time relationship, means (132) responsive to said current signal to produce a third control signal (STOP) when said current signal exceeds a predetermined level, means for applying said third control signal to said means for generating and varying said second control signal to maintain said time relationship in the state existing at the time of occurrence of said third control signal.

Claim 10

In an ink jet apparatus which comprises means (21) for supporting a record medium (20), means including a nozzle (12) and an ink conduit (14) for producing at least one ink jet (16) which propagates along a path directed to said supporting means (21) and, and in the course of a drop formation process, disintegrates into a train of drops (18) and a point of drop formation, an electrode system (22) including control electrode means (24) positioned at said point of drop formation, and deflection electrode means (28) extending along said path between said point of drop formation and said supporting means (21), means affecting said drop formation process, said means being responsive to a first control signal, means (34) for generating said first control signal, an ink electrode (30) positioned in said ink conduit, (14), means for producing relative motion between said supporting means (21) and said ink jet, means (40) responsive to said relative motion to produce a position signal (PIXEL) indicating the relative position between said ink jet producing means (12, 14) and said supporting means (21), first means (44, 54) for producing first electrical pulses (PRINT), said means being responsive to a recording control data signal, said position signal and said first control signal, first coupling means (53) for coupling said first electrical pulses to said control electrode means (24), means including delay means (50) for coupling said first electrical pulses across said ink electrode (30) and said control electrode (24), said pulses selectively applying electrical charges to said drops which charges determine the amount of deflection of the drops by said deflection electrode such that the drops are either allowed to proceed to said record medium or are intercepted, a circuit (FIG. 8) for controlling the relative timing of said electrical pulses and said drop formation process, said circuit comprising second means (151) for generating second electrical pulses in response to said first control signal; means (50, 101) for coupling said first control signal (from oscillator 34) t said second pulse generating means (151) second coupling means (152) for coupling said second electrical pulses from said second pulse generating means (151) across said ink electrode (30) and said control electrode (24) means (130, 131) for sensing a current comprised of the electrical charges which are applied to said drops by said second electrical pulses to produce a current signal, means for varying the time relationship between said first and second electrical pulses and said drop formation process in response to a second control signal, means (149) for producing and varying said second control signal and applying said variable second control signal to said time relationship varying means to vary said time relationship, means (132) responsive to said current signal to produce a third control signal (STOP) when said current signal exceeds a predetermined level, means for applying said third control signal to said means for generating and varying said second control signal to maintain said time relationship in the state existing at the time of occurrence of said third control signal.

Claim 11

The circuit of claim 6 wherein said means for varying the time relationship comprises said delay means (50), the delay of which be variable in response to said second control signal.

Claim 12

The circuit of claim 6 wherein said means for producing and varying said second control signal comprises a saw-tooth generator (149) which is started by a start signal from an external source and is stopped by said third control signal.

Claim 13

The circuit of claim 6 wherein said means (132) responsive to said current signal comprises a comparator having a first input coupled to receive said current signal and a second input coupled to receive a reference signal.

Claim 14

The circuit of claim 6 wherein said second pulse generating means comprises a circuit (210, 212, 214, 216, 218, 220, 222, 224) to produce pulses (FIG. 6) which comprise a positive going portion and a negative going portion.

Claim 15

The circuit of claim 10 wherein said positive and negative portions are spaced.

Claim 16

The circuit of claim 6 wherein said means for coupling said first electrical pulses and said means for coupling said second electrical pulses comprise switch means (101) for selectively coupling said first control signal to said first and second pulse generating means.