| 摘要 |
PURPOSE:To accurately perform detection and to prevent erroneous detection caused by instantaneously generated noise, by comparing the signal obtained by integrating the output of a sensor and the signal corresponding to the output signal of the sensor and further integrating the compared output while comparing this integration signal with a reference signal to output the same. CONSTITUTION:A sensor 1 outputs the signal based on a light receiving element as V1 while this output V1 is outputted as an integration signal V2 through an integrating circuit 2. Further, the output V1 is divided to voltage V3 by a voltage divider circuit 3. These voltages V2, V3 are compared by a comparator circuit 4 and, if either one of them becomes higher, both outputs are reversed. In the next step, output VO outputted from the comparator circuit 4 is further integrated by an integrator circuit consisting of a resistor R13 and a condenser C2 to be supplied to a comparator 40 as voltage V6 while reference voltage V6 is supplied to the comparator 40. Therefore, even if the output VO of the comparator 4 comes to H by a noise signal, the output thereof is integrated and, therefore, the output VO comes to L before voltage V5 becomes higher than V6 and erroneous detection caused by noise can be prevented and the detection of paper can be performed with higher accuracy. |
