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CROSSTALK CORRECTION FOR IONOGRAPHIC HEAD HAVING SLIT APERTURES

IP.com Disclosure Number: IPCOM000026333D
Original Publication Date: 1991-Jun-30
Included in the Prior Art Database: 2004-Apr-05
Document File: 4 page(s) / 148K

Publishing Venue

Xerox Disclosure Journal

Abstract

Ionographic heads generally incorporate slits or holes for the ion exit aperture. The modulation elements in slit designs are placed close together, and as a consequence, the output ion current from each element suffers from signal crosstalk from neighboring elements. This is because the fields of each modulating element, or nib, partially extend into the space over their neighbors and influences their output. The degree of crosstalk can be reduced, for example, by reducing the exit slit width but at the cost of lowering net ion throughput. Individual exit ion holes do not suffer from this problem, but have other architectural and fabrication disadvantages and generally require higher modulation voltages. One solution is to predistort the applied nib modulating voltages to compensate for the crosstalk field. It has been shown that if the crosstalk coupling can be considered linear and the coupling only extends to a few nearest neighbors, the predistorted nib potentials that are required turn out to be a simple weighted sum of the straight input nib potentials, and only the nearest neighboring potentials are involved in the

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XEROX DISCLOSURE JOURNAL

CROSSTALK CORRECTION FOR IONOGRAPHIC HEAD HAVING SLIT APERTURES
Frank C. Genovese
Tracy E. Thieret

Proposed Classification US. C1.346/159
Int. C1. Gold 15/06

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/ ONE CYCLE / DELAY

/

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I FIG. i-

XEROX DISCLOSURE JOURNAL - Vol. 16, No. 3 May/June 1991 161

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CROSSTALK CORRECTION FOR IONOGRAPHIC HEAD HAVING SLIT APERTURES(Cont'd)

Ionographic heads generally incorporate slits or holes for the ion exit aperture. The modulation elements in slit designs are placed close together, and as a consequence, the output ion current from each element suffers from signal crosstalk from neighboring elements. This is because the fields of each modulating element, or nib, partially extend into the space over their neighbors and influences their output. The degree of crosstalk can be reduced, for example, by reducing the exit slit width but at the cost of lowering net ion throughput. Individual exit ion holes do not suffer from this problem, but have other architectural and fabrication disadvantages and generally require higher modulation voltages. One solution is to predistort the applied nib modulating voltages to compensate for the crosstalk field. It has been shown that if the crosstalk coupling can be considered linear and the coupling only extends to a few nearest neighbors, the predistorted nib potentials that are required turn out to be a simple weighted sum of the straight input nib potentials, and only the nearest neighboring potentials are involved in the

SUm.

The weighted summation of potentials can be easily accomplished in principal by synthesizing a resistor network such that each output nib is tied to its nominal input potential plus neighboring input potentials through resistors providing the different weighting factors. The problem is that some of the coefficients are negative. The negative coefficients can be supplied by providing an inverter for each input potential to which the negative terms (resistors) connect. This is impractical at the nib level since each nib would need an inverter as well as the weighting resistor.

In multiplex head designs all the nibs are fed by a common data bus with a relatively small number of elements. It is proposed that each busline drive circuit include an inverter and weighted resistor network so that t...