Browse Prior Art Database

Velocity Control System for Ink Jet Printer

IP.com Disclosure Number: IPCOM000087701D
Original Publication Date: 1977-Mar-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 5 page(s) / 145K

Publishing Venue

IBM

Related People

Arnold, RW: AUTHOR [+3]

Abstract

A magnetic ink jet printer system (Fig. 1) comprises a nozzle 10 through which a stream of ferromagnetic ink is ejected under pressure supplied by a pump 13. Drops 14 formed in the ink stream are projected toward a print medium 15. Drops not used for printing are deflected from the initial stream trajectory by a magnetic selector 16 into a gutter 17 located in advance of the record medium. A raster scan signal is applied to a deflector 18 which disperses the ink drops orthogonal to the initial trajectory to be deposited on the record medium in a data pattern.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 33% of the total text.

Page 1 of 5

Velocity Control System for Ink Jet Printer

A magnetic ink jet printer system (Fig. 1) comprises a nozzle 10 through which a stream of ferromagnetic ink is ejected under pressure supplied by a pump 13. Drops 14 formed in the ink stream are projected toward a print medium 15. Drops not used for printing are deflected from the initial stream trajectory by a magnetic selector 16 into a gutter 17 located in advance of the record medium. A raster scan signal is applied to a deflector 18 which disperses the ink drops orthogonal to the initial trajectory to be deposited on the record medium in a data pattern.

Ink drop detectors 20 and 21 located proximate the trajectory of the ink drops 14 are spaced one drop wavelength apart to generate pulses converted by a velocity variance circuit to indicate the direction of a velocity error to a magnitude compare store 23. The output of the compare store 23 is gated out by a sample control signal to either a coarse control loop or a fine control loop, which operates to make coarse or fine adjustments to pump 13 for rapidly correcting errors in the velocity of the ink drops 14.

The coarse control loop comprises a coarse converge circuit 24 having a 6- stage output connected to a coarse counter 25. The 6-bit output of the coarse counter is connected to a coarse digital/analog convertor (DAC) 26. The voltage output from coarse DAC 26 is applied to an operational amplifier 27 for regulating the amount of correction of pump 13.

The output of the coarse counter 25 is also connected to decodes 33 and 34, which provide feedback signals through NAND gate 35 to load latch 36, which, when cleared by a decode 63 or decode 0 from coarse decodes 33 and 34, respectively, loads the count condition from converge circuit 24 to the coarse counter 25.

The fine control loop comprises a fine convergence circuit 29 (Fig. 2) connected to the count-up and count-down outputs of comparator store 23. The convergence circuit 29 has a 6-bit output which is converted to a 5-bit output by NOR gate 30, which is connected to a fine counter 31. The 5-bit output of fine counter 31 is connected through fine DAC 32 to the operate amplifier 27.

The output from fine counter 31 is connected to fine decodes 37 and 38 which generate and transmit the fine decode 0 and fine decode 31 signals to NAND gate 39 and 40 (Fig. 1) connected to the up/down inputs, respectively, of coarse counter 25. The fine decode 31 signal from fine decode 38 is also applied to AND gate 41 for resetting the converge circuit 24. A mode latch 42 provides coarse and fine signals to control the loading of the coarse counter 25 (Fig. 1) and the fine counter 31 (Fig. 2).

A third velocity control loop comprises super-coarse counter 45 having a 4-bit output connected to super-coarse DAC 46, which in turn applies an output voltage to the operational amplifier 27 for driving pump 13. Super-coarse counter 45 and super-coarse DAC 46 provide a third level of adjustment greater t...