Non-impact printer apparatus with improved current mirror driver

In a non-impact printer apparatus such as an LED printhead a current mirror driver is used to control current to the recording elements, e.g., LED's. The current mirror driver is incorporated in an integrated circuit driver chip and a plurality of these chips are provided on the printhead. Each...

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Bibliographic Details
Main Authors SMALL; JEFFREY A, HADLEY; MARY A
Format Patent
LanguageEnglish
Published 23.11.1993
Edition5
Subjects
CORRECTION OF TYPOGRAPHICAL ERRORS
i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME
LINING MACHINES
PERFORMING OPERATIONS
PRINTING
SELECTIVE PRINTING MECHANISMS
STAMPS
TRANSPORTING
TYPEWRITERS
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Summary:In a non-impact printer apparatus such as an LED printhead a current mirror driver is used to control current to the recording elements, e.g., LED's. The current mirror driver is incorporated in an integrated circuit driver chip and a plurality of these chips are provided on the printhead. Each chip includes two sets of digitally addressable transistors. This allows for individual chip control of current to the respective LED's to correct for nonuniformity of light output from chip to chip due to temperature gradients as well as controlling for light output due to aging of the printhead. A continuously conducting transistor is associated with each set of addressable transistors to provide a minimum offset bias current level and selective activation of the addressable transistors provides for selective increase of a bias current over the minimum level. The bias current is mirrored in those LED's selected for activation.
Bibliography:Application Number: US19920825459