Tdk Corporation

Takehiro Imai

Shiro Nakagawa

Taisuke Domon

Atsuko Tsuchida

Eiji Takahishi

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.

Toner concentration detector for a two-component developer

A humidity meter includes a humidity-frequency converter which is essentially a pulse oscillator, the frequency of which depends upon the impedance of a humidity sensor, a pulse width modulator for adjusting pulse width of an output pulse of the converter for assuring a linear relationship between humidity and the output signal, and an integrator for integrating the output of the pulse width modulator to provide an output signal as a DC level. A feedback path is provided to apply the output signal to the pulse width modulator for assuring a linear output irrespective of the exponential characteristics of the humidity sensor.

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Chiba, Japan

Takehiro Imai