APPARATUS AND METHOD FOR CALIBRATING A PRINTER TO PRINT DATA AT A SPECIFIED DISTANCE FROM THE REFERENCE EDGE OF A DOCUMENT

摘要

of The Disclosure A method for calibrating a printer to print data beginning at a specified distance from the reference edge of a document. Several test documents are moved through a print station and a test symbol is printed on each of them with a preselected set of heating elements from a dot matrix thermal printer. The test documents are then processed through the same print station whereupon a sensor detects the reference edge of the document and the test symbol. A master controller then determines a test symbol distance between the reference edge and the midpoint of the test symbol for each test document. A plurality of test documents is processed in this manner, and the master controller determines an average test symbol distance for the plurality of test documents. Using an average test symbol distance, the master controller determines the distance between the sensor and a given heating element of the thermal printer. The master controller then calculates a calibration distance which is based on a comparison of actual distance between the reference edge and the preselected heating elements versus average test symbol distance. In order to calibrate the printer to account for the calibration distance so that the printer prints data beginning at substantially the specified distance from the reference edge of the document, the master controller utilizes a stepping motor to make coarse calibration adjustments by advancing the document in full and/or half steps. Fine calibration adjustments are made by selectively energizing heating elements of the thermal printer at the print station. An apparatus is also provided which will print data starting at the specified distance from the reference edge of the document.