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Position and Synchronization Sensor for an Ink Jet Printer

IP.com Disclosure Number: IPCOM000078629D
Original Publication Date: 1973-Feb-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Ruddy, GA: AUTHOR

Abstract

A position sensor provides the necessary feedback loop for the exact placement of all drops printed on a document in an ink jet printer and determines if drops are being charged or not (drop synchronization).

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Position and Synchronization Sensor for an Ink Jet Printer

A position sensor provides the necessary feedback loop for the exact placement of all drops printed on a document in an ink jet printer and determines if drops are being charged or not (drop synchronization).

The basic physical structure is displayed in Figs. 1 and 2. Capacitive coupling occurs between charged ink drops 1 and the position sensors 2, placed along path 3 followed by the ink drops through opening 4 in shield 5. Sensors 2 are ends of pieces of fine wire and act as one plate of a capacitor. The ink drop acts as the other plate, negatively charged. As an individual ink drop passes in front of the sensing array, several sensors register outputs. The magnitude of the outputs is a function of both the charge on the drop and the proximity of the drop to any given sensor. The outputs are fed to control logic, not shown, and compared with reference data. The reference data would include information such as which sensor should have registered the peak response and what amplitude that peak response should have been. Automatic adjustments are then made to increase or decrease the voltage applied to succeeding drops.

Sensing of drop synchronization is done by sensing a very small charge on drops when they are being directed into a lower gutter, not shown.

Position sensing, as described, allows for extremely accurate placement of the drops on the output document, by providing a continuous feedback loop to the control and charging logic. Position sensors 2 are positioned for detection of drop charges after all voltage error and most dynamic...