In situ ionographic uniformity correction

The In Situ Ionographic Uniformity Correction is a method and apparatus which solves the problem of non-uniform density of ion current projected from an ionographic print head (10) caused chiefly by variations in the dimensions of the modulation channel (24). During calibration, the present inventio...

Full description

Saved in:
Bibliographic Details
Main Author STEARNS, RICHARD G
Format Patent
LanguageEnglish
French
German
Published 24.04.1996
Edition6
Subjects
CINEMATOGRAPHY
CORRECTION OF TYPOGRAPHICAL ERRORS
ELECTRIC COMMUNICATION TECHNIQUE
ELECTRICITY
ELECTROGRAPHY
ELECTROPHOTOGRAPHY
HOLOGRAPHY
i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME
LINING MACHINES
MAGNETOGRAPHY
PERFORMING OPERATIONS
PHOTOGRAPHY
PHYSICS
PICTORIAL COMMUNICATION, e.g. TELEVISION
PRINTING
SELECTIVE PRINTING MECHANISMS
STAMPS
TRANSPORTING
TYPEWRITERS
Online AccessGet full text

Cover

More Information
Summary:The In Situ Ionographic Uniformity Correction is a method and apparatus which solves the problem of non-uniform density of ion current projected from an ionographic print head (10) caused chiefly by variations in the dimensions of the modulation channel (24). During calibration, the present invention senses ion current (20) using a simplified ion sensor (36) which has an electrode (32), very large in proportion to the width of several modulation electrodes (22). Groups (60), (61) of modulation electrodes (22) are electronically addressed in steps of one modulation electrode (22) each, across the width of the print array (16). To prevent cross-talk from rendering the sensed ion current (20) values unusable, the modulation voltage (Vm(i)) is adjusted by a feedback circuit (42) to achieve a fixed value of ion current (20) for each group (60), (61). Values of this modulation voltage (Vm(i)) are stored in an electronic data file (44). Computation of corrected modulation voltage (Vm(i)') to produce uniform ion current (20), based on average modulation voltage and a print head (10) characteristic constant, is made in a data processor (46) by a programmed algorithm which accesses the data file (44). Corrected values of modulation voltage (Vm(i)') are applied to each correlated modulation electrode (22) through a switching circuit (52). Corrected values of modulation voltage (Vm(i)'), when applied to the correlated modulation electrodes (22), produce ion currents (20) of uniform density and result in uniformity of density in large, grey printed areas.
Bibliography:Application Number: EP19910311924