| 摘要 |
PURPOSE:To prevent trouble of high voltage power supply due to breakdown of corotron wires or the like, by integrating output current from the high voltage power supply, actuating a protective circuit when this integrated value exceeds a specified value, and stopping this power supply. CONSTITUTION:Low resistor 4 is inserted into the line of high voltage power supply 1 for the corotron, control current i1 is detected as a resistance across both the terminals of resistor 4, and this detected voltage is applied to integrating circuit 5. Clearance signals (e) are produced from controller 6 of the copier to reset the integrated values in integrating circuit 5 at start of copying and at intervals of a constant time length from the start. Integrated values (b) are compared to reference voltage V1 in comparator 7, and compared to reference voltage V2 lower than voltage V1 in comparator 9. When value (b) exceeds voltage V1, a signal is generated from comparator 7 to stop high voltage power supply 1. When value becomes smaller than V1 but greater than V2, necessary indication is made by warning output (d) from comparator 9. |
