Ebara Corporation

Atsushi Abe

Taro Takahashi

Hiroaki Shibue

Shinpei Tokunaga

Katsuhide Watanabe

Hiroto Yamada

An eddy current sensor has an exciting coil and a detection coil. A holding circuit holds reference data indicating a characteristic of an output signal output from the detection coil at a reference state and outputs the reference data at a state other than the reference state. A pseudo signal generating circuit generates and outputs a balance coil pseudo signal corresponding to the output signal output from the detection coil at the reference state from the reference data output from the holding circuit. A bridge circuit, at the state other than the reference state, receives the output signal output from the detection coil and the balance coil pseudo signal and outputs a bridge output signal corresponding to a difference between the output signal and the balance coil pseudo signal as a bridge output signal.

Output signal processing apparatus for eddy current sensor

An eddy current sensor assembly includes an eddy current sensor and an output signal processing circuit that processes an output signal from the eddy current sensor. The output signal processing circuit includes a mixer circuit that accepts the output signal and a signal of the predetermined frequency as input, multiplies the two signals received as input, and outputs an output signal obtained by the multiplication, and a low-pass filter that accepts the output signal output by the mixer circuit as input, cuts a high-frequency signal included in the output signal received as input, and outputs at least a direct-current (DC) signal.

Output signal processing circuit for eddy current sensor and output signal processing method for eddy current sensor

The eddy current sensor for measuring the film thickness of a conductive film formed on a substrate includes a core made of a magnetic material that has a base portion, and outer legs provided to the base portion at both end portions in a first direction of the base portion respectively, an excitation coil that is arranged on the core and forms an eddy current in the conductive film, and a detection coil that is arranged on the core and detects the eddy current formed in the conductive film. The length of the base portion in the first direction is not less than the length of the base portion in a second direction that is substantially orthogonal to the first direction.

Growing community of inventors

Tokyo, Japan

Atsushi Abe