| 摘要 |
<p>A reference medium is scanned with a beam from a medium sensor (44) for detecting a printing medium of relatively low transmittance at high accuracy and a beam from a medium sensor (45) for detecting even a medium of high transmittance at low accuracy so as to determine edge positions Ry0, Ry1 of the reference medium. The difference Diff0 between the edge positions are calculated as a correction and stored. If a printing medium is hard to detect by means of the medium sensor (44), the medium sensor (45) is used to detect the medium, and the edge positions determined by the detection are corrected using the correction Diff0. A first drive level for driving a light source at which the output of the sensor (44) when it senses a printing medium is of a predetermined level and a second drive level for driving the light source at which the output of the sensor (45) when it senses the printing medium is of a predetermined level are determined so as to identify the type of the printing medium on the basis of the difference between the drive levels. Thus, any of a wider variety of types of printing medium can be read at high accuracy.</p> |
