Functions operation When a document is placed on the glass and the ADF unit is closed or at an angle of less than 30 degrees, the SCB begins to detect the presence and size of the document. The SCB monitors outputs from the flatbed document detection sensor (SCNSIZE1S) and the flatbed document size detection sensors (SCNSIZE2S, SCNSIZE3S, and SCNSIZE4S). The SCB passes the signals from the sensors to the CPB. The reflecting sensor detects the presence and size information of the document based on whether the photoreceptor can receive the emitted light from the luminous body of the sensor.
When a document is on the glass, the document reflects the emitted light and the photoreceptor can receive the reflected light. When there is not a document on the glass, the emitted light passes through the glass and the photoreceptor cannot receive the emitted light. Figure 52. Functions operation C8523-90921 Flatbed operation 85