| 摘要 |
PURPOSE:To detect the edge of a flat plate body at a high speed without converting a photosensor output from analog to digital by controlling the light intensity of a light source by binary-coded data and processing the photosensor output through an analog comparator. CONSTITUTION:When a body 3 is absent, a light source 11 and a photosensor 12 enter scanning operation through a light source switching circuit 5 and a photosensor switching circuit 6. The output Sx of the sensor 12 passed through an amplifier 7 is compared by the analog comparator 14 with three-level reference values SL1-SL2, the output current of a photoelectric driving power source 12 is adjusted by a control signal passed through a D/A converter 13 so that the output Sx is equal to one reference value SL, and this control signal is stored in a memory for correction data on the quantity of the light source. The output of the sensor 21 when the flat plate body 3 is inserted in a reference state based upon said data is processed by the comparator 14 to generate a binary output corresponding to whether the body 3 is present or not without converting the output of the sensor 21 from analog to digital. Therefore, the scanning speed is not influenced by the fast A/D converter and the edge part of the flat plate body is detected at a high speed. |
