1. Technical Field
The present invention relates to an image printing apparatus and a method for calibrating (i.e., correcting) the image printing apparatus.
2. Related Art
In the technical field to which the present invention pertains, an image printing apparatus that has a sensor that is capable of detecting the edges of a sheet of print target paper is known. An example of such an image printing apparatus having a paper-edge detection sensor known in the art is described in JP-A-2003-305888. In a manufacturing process of the related-art image printing apparatus disclosed in JP-A-2003-305888, “black” printing is performed in a print area inside a paper-margin area with a predetermined width of paper margin being left along each edge of a sheet of printing paper. Then, using the paper-edge detection sensor thereof, the related-art image printing apparatus disclosed therein measures a distance between each edge (i.e., border) of the print area and the corresponding edge of the sheet of printing paper. The related-art image printing apparatus disclosed therein stores a difference between the measured distance and a predetermined reference margin width as a calibration value (i.e., correction value). Using the stored calibration value, the related-art image printing apparatus disclosed in JP-A-2003-305888 performs the calibration (i.e., adjustment) of the paper-edge detection sensor thereof.
Disadvantageously, since the sensor-calibration measurement is conducted only once in the manufacturing process thereof, which means that it will not be conducted after the actual use thereof, it is practically impossible, or at best difficult, for the related-art image printing apparatus disclosed in JP-A-2003-305888 to prevent the detection accuracy of the paper-edge detection sensor thereof from decreasing as time elapses due to the aged deterioration of the paper-edge detection sensor thereof. Even if it is modified to conduct the sensor-calibration measurement after the actual use thereof, since it is necessary to perform black printing, the related-art image printing apparatus disclosed in JP-A-2003-305888 disadvantageously consumes considerable amount of a coloring matter such as ink for such a purpose.