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Charge Electrode Driver for Ink Jet Printer

IP.com Disclosure Number: IPCOM000048111D
Original Publication Date: 1981-Dec-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Mathews, HP: AUTHOR [+2]

Abstract

The driving circuit shown above provides a drop charge voltage at the output node 10. A charge electrode places the charge on ink drops in an ink jet printer. Unwanted drops are charged enough so that an electric field deflects them to a gutter. Print drops are charge correct their flight path for aerodynamic effects and charge interaction effects. In the above circuit, the gutter voltage and print compensation voltages are referenced to each other but are independently adjusted. In addition, additive factors to the print compensation voltage may be combined with that voltage without requiring a separate adjustment.

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Charge Electrode Driver for Ink Jet Printer

The driving circuit shown above provides a drop charge voltage at the output node 10. A charge electrode places the charge on ink drops in an ink jet printer. Unwanted drops are charged enough so that an electric field deflects them to a gutter. Print drops are charge correct their flight path for aerodynamic effects and charge interaction effects. In the above circuit, the gutter voltage and print compensation voltages are referenced to each other but are independently adjusted. In addition, additive factors to the print compensation voltage may be combined with that voltage without requiring a separate adjustment.

In operation, a transimpedance amplifier 12 converts input current signals at its negative input into voltage signals for application to the charge electrode through resistor R12. The current signal for a gutter voltage comes through gutter voltage switch 14. The current used to generate the gutter voltage is supplied by a precision current mirror circuit made up of operational amplifier 16, transistors T1 and T2, and resistors R6 and R7. This current mirror circuit utilizes the reference current for the gutter voltage generated from operational amplifier 18 through resistor R13. Operational amplifier 18 is adjustable in its output by adjusting the 2 Potassium potentiometer R1.

In order to reference the gutter voltage to the print voltage adjust, the output of amplifier 18 also provides the voltage drop acro...