| 摘要 |
PURPOSE:To surely prevent a printing action from being continuously executed if no toner is existing in a developing device. CONSTITUTION:By a magnetic sensor 26, the magnetic flux density of the toner T in a toner case 9 is detected and a detection signal Va having a level corresponding to the magnetic flux density is outputted to a CPU 28. By the CPU 28 alphano toner 1' is judged when the amplitude of the signal Va becomes equal to or under the prescribed amplitude H1. Then, when the number of printing sheets at and after the judgement arrives at 50 sheets, prescribed display is executed on a liquid crystal display part 32. Besides, when the number of printing sheets at and after the display arrives at 50 sheets, the printing action of an image forming part 31 is stopped by the CPU 28. When the amplitude of the signal Va becomes equal to or under the prescribed amplitude H2 being smaller than the amplitude H1 and the minimum value of the signal Va becomes equal to or under the prescribed minimum value Vmin, 'no toner 2' is judged by the CPU 28. Then, the printing action of the image forming part 31 is stopped by the CPU 28 when 'no toner 2' is judged before the number of printing sheets at and after the display arrives at 50 sheets. |
