| 摘要 |
PURPOSE: To detect the abnormality of a paper sensor while the device stands by without necessitating a complicated circuit by detecting whether or not the output level of the paper sensor is changed. CONSTITUTION: The output of the light receiving element 24b of the paper sensor 24 is inputted in the input port X of a CPU 31 through an inverter 32. When the paper P exists between a light emitting element 24a and the light receiving element 24b, an L level signal is inputted in the input port X. When a device main body cover is opened, an interlock switch 33 is in an open state and the L level signal is inputted in the input port Y of the CPU 31 through the inverter 34. When the interlock switch 33 is closed in a copying standby state after a power source is turned on, the CPU 31 judges whether or not the output level of the sensor 24 is changed. In the case of judging that the output level is changed specified number of times for a specified time, a warning that the abnormality of the paper sensor 24 is detected is displayed on a display panel 35. |
