| 摘要 |
PROBLEM TO BE SOLVED: To adjust effective toner density or an effective toner amount (a toner amount in the case of a differential output from a differential transformer equaling a target value) just by adjusting a variable resistor with minimal influence to differential sensitivity.SOLUTION: A toner sensor includes: an oscillation circuit; a differential transformer that is constituted by a drive coil whose one end and the other end are both connected to the oscillation circuit and by reference and detection coils connected magnetically to the drive coil, of which an output voltage of the detection coil is changed on the basis of a change in inductance due to influence of a developer consisting of toner and outputs, as a differential output, a difference between the reference coil and detection coil in output voltage; a resistance voltage-division circuit whose one end is connected to the other end of the drive coil via the oscillation circuit and whose other end is connected to the ground, and that is constituted by a variable resistor; and a capacitor whose one end is connected to the resistance voltage-division circuit and whose other end is connected to the detection coil on its ground side. Further, a voltage divided by the resistance voltage-division circuit is added to a voltage of the detection coil on the ground side via the capacitor. |
