Toner concentration detector for a two-component developer
AssigneeTDK Corporation
InventorsShiro Nakagawa, Taisuke Domon, Takehiro Imai, Eiji Takahishi
Life of this patent
Estimating the term…
Abstract
A toner concentration detecting device for detecting a toner concentration of a two component developer including a differential transformer which is connected with a phase detecting circuit. A variable capacitance diode is connected between the primary coil and the secondary coil and a variable resistor is provided to supply the variable capacitance diode with a DC voltage to vary the capacitance of the diode. The variable resistor and DC voltage are located at a remote location from the transformer.
Claims5
In a toner concentration detector including a differential transformer means having primary and secondary coils having a coupling coefficient therebetween for producing a differential output from the secondary coil and capacitive circuit means for adjusting the coupling coefficient between said primary and secondary coils, the improvement residing in said capacitive circuit means including means for reducing high frequency noise resulting from current conducted through extension wiring means and a variable capacitive diode capacitively coupled between said primary and secondary coils, and separate adjustable means for applying a voltage for varying the capacitance of said variable capacitive diode to control the coupling coefficient between said primary and secondary coil, the extension wiring means interconnecting the primary and secondary coils with the separate adjustable means to be located at an accessible location remote from the transformer means.
Dependencies are inferred from the claim text.