| 摘要 |
PURPOSE:To detect the presence or absence of powder at almost the same level without being influenced by the variation of a physical property of the powder, and to hold the same level by a signal ratio of each detecting means even if the variation occurs in using environment, by providing two developer detecting means having a different position. CONSTITUTION:Developer quantity detecting means 5a, 5b are placed at the upper and lower different positions to utilize the variation of magnetic permeability of the developer. The means 5a and 5b are connected to converters 6a, 6b for converting the variation of coil inductance to its corresponding voltage, and an operator 7. The operator 7 uses a detecting signal of the means 5b as a reference to operate a ratio with a detecting signal of the means 5a. Its operation result is inputted to a comparing circuit 8 to compare the operator outut with the reference (c) of the residual quantity limit set in advance, to binary-code it, and to decide the residual quantity of the developer. Its result is outputted to a display device 9 of the developer supply. |
