Electrophotographic printer having transferring device with control mode switching control

摘要

A sensor detects the leading edge of the print medium. A position counter counts a time length required for the print medium to advance from where the print medium is detected by the sensor to the photosensitive drum. The position counter also counts a time length for the print medium to advance past the photosensitive drum. The distance of the toner image from the leading edge of the print medium is determined on the basis of the image data of print data. A row counter counts the number of dots in a direction in which the print medium is transported and a column counter counts the number of dots in a direction perpendicular to the direction the print medium is transported. The distance between the first line of an image data and the line in which a first dot to be printed in the image data is determined on the basis of the contents of the column counter and the row counter. The controller switches the transferring device from the constant current control mode to the constant voltage control mode immediately before the first line is printed on the print medium, thereby allowing transferring of the toner image in accordance with the distance of the toner image from the leading edge of the print medium.