MAGNETIC IMAGE QUALITY CONTROL FOR MICR ELECTROPHOTOGRAPHIC PRINTERS
Original Publication Date: 1989-Apr-30
Included in the Prior Art Database: 2004-Apr-04
Xerox Disclosure Journal
Electrophotographic printing has been particularly useful in the commercial banking industry by reproducing checks or financial documents with magnetic ink. Each financial document has imprinted thereon encoded data in a magnetic ink character recognition (MICR) format. One important aspect is to verify that the images reproduced in the MICR format are magnetically acceptable to the established banking industry equipment that operates on these documents, e. g. readerskorters. This may be accomplished by using pre-printed MICR calibration forms. A portion of this form has a MICR test pattern that is known to produce acceptable magnetic signal characteristics. An electronically encoded form of the test pattern is stored in the printer's memory. When the user desires to check if the printer is producing magnetically acceptable images, the pre-printed calibration forms are loaded into the printer and the user energizes a test button. The printer will then produce the test pattern stored therein on. a portion of the calibration form. The form will pass under a magnetic head that will magnetize the images which than pass through a read head that will sense the reference image, store it, sense and store the experimental image, compare the two and generate an error signal. The error signal takes into account both amplitude and sign. This error signal is then used in a control algorithm that determines the adjustments in the processing parameters to be made, e. g. an adjustment in the developer roll bias of the magnetic brush development station. The differential rather than absolute method of measurement is of primary importance and facilitates implementation over a large population of mass produced MICR printers.