| 摘要 |
<p>PROBLEM TO BE SOLVED: To solve such a problem that discomfort may be given to a user when size of an original cannot be accurately detected because of influences of an ambient environment such as humidity, or in accordance with a detection system.SOLUTION: An image reading apparatus is provided in which an original placed on original platen glass and pressed by an openable and closable original pressing plate is irradiated with light from a light source, and reading means reads an image of the original on the basis of light reflected by the original. The image reading apparatus performs following processing, namely, detects a change in electrostatic capacitances to be detected by sensors provided at a plurality of predetermined places in the original pressing plate and a reference sensor when the original is placed on the original platen glass and the original pressing plate is closed, and detects a change in an electrostatic capacitance to be detected by the sensors and the reference sensor when the original is not placed. On the basis of a difference between the change in the electrostatic capacitances of the sensors to be detected and a change in an electrostatic capacitance of the reference sensor, the image reading apparatus determines whether the original is present at positions where the sensors are installed or in the vicinity of the positions. On the basis of the determination, the image reading apparatus establishes a size of the original.</p> |
