Digital phase control for an ink jet recording system

Claim 2

In an ink jet printing system which comprises an ink supply means, nozzle means for forming an ink droplet stream as ink emanates therefrom, drop forming means associated with said nozzle causing said ink droplets to form at a substantially predetermined rate, charging means for selectively charging droplets emanating from said nozzle, sensing means for detecting the presence of a charge on said droplets, deflecting means for electrostatically deflecting said droplets, record receiving means for receiving said droplet stream, and synchronizing means for synchronizing the application of an electrostatic charge on individual ink droplets with the formation of said ink droplets, the improvement in said drop forming and charge application synchronization means which comprises: means for supplying at least one test pulse to the droplet charging means having a predetermined known phase relationship with respect to pulses supplied to the drop forming means, means for specifying the phase of at least one test pulse, said sensing means including means operable to determine if the test pulses result in full charging of the ink droplets, storage means for storing phase information related to the last generated at least one test pulse, and said specifying means including means for utilizing the phase information in said storage means for generating the next series of charging pulses during the next subsequent test cycle.

Claim 3

An ink jet printing system as set forth in claim 1 including means for accessing the stored phase relationship from said storage means and means utilizing said accessed information to control the phase of the pulses applied to said charging means during a subsequent printing cycle.

Claim 4

An ink jet printing system as set forth in claim 2 including means for altering the phase information contents of said storage means in a first manner in the case of a successful charging of individual ink droplets and means for altering the phase relationship information in said storage means in a different manner when said ink droplets are not successfully charged.

Claim 5

An ink jet printing system as set forth in claim 3 wherein said means for supplying a series of test pulses includes a system clock which produces a predetermined number of phased pulse output sequences including the pulses supplied to the drop forming means and means for selecting only a predetermined phase sequence of said pulses at any one time for supplying to said electrostatic drop charging means.

Claim 6

An ink jet printing system as set forth in claim 4 wherein said selecting means includes a digital decoder and gating circuit means controlled thereby, said digital decoder including means for gating the contents of said storage means in digital form thereto and means for storing said phase information in said storage means in digital form.

Claim 7

An ink jet recording system as set forth in claim 5 wherein said means for producing said at least one test pulse includes means for producing a series of test pulses to be supplied to said charging means whereby the signal-to-noise ratio in the sensing circuitry is improved.

Claim 8

An ink jet recording system as set forth in claim 5 including means associated with said synchronization circuitry for initiating further test cycles wherein, during each test cycle, test pulses are generated having different phase relationships until a Successful charging of said ink droplets is detected and means for activating a print cycle subsequent to said successful sensing operation.

Claim 9

An ink jet printing system as set forth in claim 5 including means for incrementing the phase relationship number in said storage means in the event that a given series of test pulses does not result in the successful sensing of a charge and means for decrementing said stored phase number in the event that successful charging of the pulses does occur.

Claim 10

An ink jet printing system as set forth in claim 2 including a decoder for controlling the application of the stored phase information during a print cycle and means causing an automatic and fixed decrement of said phase information number whereby the print cycle charging pulse is placed on the charging means at an earlier point in time than the test pulse derived from the same signal.

Claim 11

In an ink jet printing system which comprises an ink supply means, nozzle means for forming an ink droplet stream as ink emanates therefrom, drop forming means associated with said nozzle causing said ink droplets to form at a substantially predetermined rate, charging means for selectively charging droplets emanating from said nozzle, sensing means for detecting the presence of a charge on said droplets, deflecting means for deflecting said droplets, record receiving means for receiving said droplet stream, and synchronizing means for synchronizing the application of an electrostatic charge on individual ink droplets with the formation of said ink droplets, the improvement in said drop forming and charging synchronization means which comprises: means for supplying a plurality of test pulses to the droplet charging means having a predetermined known phase relationship with respect to pulses supplied to the drop forming means; said means including a system clock which produces a predetermined number of phased pulse output sequences including the pulses supplied to the drop forming means, means for selecting only a predetermined phase sequence of said clock pulses at any one time for supplying to said electrostatic drop charging means; said sensing means including means operable to determine if the test pulses result in full charging of the ink droplets, storage means for storing phase information related to the phase of the last generated test pulses; means for accessing the stored phase relationship from said storage means and means utilizing said accessed information to control the phase of the pulses applied to said charging means during a subsequent printing cycle, said last named means including means for controlling the application of the stored phase information during a print cycle, said means including a digital decoder for causing an automatic and fixed decrement of said phase information quantity whereby the print cycle charging pulse is placed on the charging means at an earlier point in time than the test pulse derived from the same signal; means for incrementing the phase relationship number in said storage means in the event that a given series of test pulses does not result in the successful sensing of a charge and means for decrementing said stored phase information quantity in the event that successful charging of the pulses does occur; and means for utilizing the phase information in said storage means for selecting the proper phased test pulse sequences as charging pulses during a test cycle.

Claim 12

In an ink jet printing system which comprises an ink supply means, nozzle means for forming an ink droplet stream as ink emanates therefrom, drop forming means associated with said nozzle causing said ink droplets to form at a substantially predetermined rate, charging means for selectively charging droplets emanating from said nozzle, sensing means for detecting the presence of a charge on said droplets, deflecting means for deflecting said droplets, record receiving means for receiving said droplet stream, and synchronizing means for synchronizing the application of an electrostatic charge on individual ink droplets with the formation of said ink droplets, the improvement in said drop forming and charging synchronization means which comprises: means for supplying a plurality of test pulses to the droplet charging means having a predetermined known phase relationship with respect to pulses supplied to the drop forming means; said means including a system clock which produces a predetermined number of phased pulse output sequences including the pulses supplied to the drop forming means, means for selecting only a predetermined phase sequence of said clock pulses at any one time for supplying to said electrostatic drop charging means; said sensing means including means operable to determine if the test pulses result in full charging of the ink droplets, storage means for storing phase information related to the phase of the last generated test pulses; means for accessing the stored phase relationship from said storage means and means utilizing said accessed information to control the phase of the pulses applied to said charging means during a subsequent printing cycle, said last named means including means for controlling the application of the stored phase information during a print cycle, said means including a digital decoder for causing an automatic and fixed decrement of said phase information quantity whereby the print cycle charging pulse is placed on the charging means at an earlier point in time than the test pulse derived from the same signal; means for incrementing the phase relationship number in said storage means in the event that a given series of test pulses does not result in the successful sensing of a charge and means for decrementing said stored phase information quantity in the event that successful charging of the pulses does occur; and means for utilizing the phase information in said storage means for selecting the proper phased test pulse sequences as charging pulses during a test cycle.

Claim 13

An ink jet printing system as set forth in claim 10 wherein storage means comprises means for storing said phase information in digital form, means for gating said digital phase information to said digital decoders in said selecting and controlling means, said storage means also including a digital counter having as many digits in its output as necessary to represent said predetermined number of phased pulse output sequences from said system clock.