| 摘要 |
<p>PURPOSE:To ensure positive detection of recording paper at low sensitivity during a steady state by providing a sensitivity change-over means which reduces the recording paper detection sensitivity of a reflection-type sensor and a recording paper detection means according to a signal from a cover open/close detecting means that detects cover open/close state. CONSTITUTION:With an operation panel being closed, a panel switch 14 is ON and thus a transistor 40 is ON, resulting in a resistance 29 and a resistance 43 being connected in parallel with reference to a light receptor 28. For this reason, unless a current flowing in the light receptor 28 is of high value, a reference voltage will not be exceeded, as a result of which the sensitivity of a reflection-type sensor 24 is kept at low level. On the other hand, with the operation panel being opened, the panel switch 14 is OFF and thus the transistor 40 is OFF, resulting in a resistance 25 and the resistance 43 being connected in parallel with reference to the light receptor 28. As a result, even a slight change in a signal within the light receptor 28 is detected, and recording paper 15 is detected positively through an increased sensitivity of the sensor 24.</p> |
