| 摘要 |
<p>PURPOSE:To prevent erroneous detection while there is no paper by detecting the absent state of the paper when a phototransistor TR detects reflected light or external light and detecting the paper when the light is shielded by the paper. CONSTITUTION:The light from a light emitting diode of a reflection type photosensor 10 is reflected to the bottom surface of an upper guide plate 2 and the light reflected therefrom is detected by the phototransistor TR. The paper advances consequently in the state of having no space at all between a lower guide plate 3 and the paper A and therefore the light from the light emitting diode is shielded and the reflected light is not detected by the TR10. The off state of the phototransistor TR is detected as the presence of the paper A.</p> |
