METHOD OF CORRECTING OPTICAL CONVERSION EFFICIENCY OF LED PICTURE ELEMENT IN DIGITAL PRINTER AND LED PRINT BAR

摘要

PURPOSE: To provide a control architecture that enables multi-exposure levels and multiple gray levels for a LED printer. CONSTITUTION: A plurality of LED chips are arranged in a row to form print bars sufficient for exposing the width of a recording medium and driver chips 22A corresponding to respective LED chips are provided in order to control the on/off time and the current being applied to each LED. The on/off time is controlled by one or a plurality of gray level strobe signal of 2 or 4 bits being decoded by a system logic 38. Characteristics of the LED are previously measured and the difference of gain thereof is stored at 42 as a correction signal which is down loaded to a LED drive circuit at the end of a record line.