Mitsubishi Denki Kabushiki Kaisha

Naohiro Mishiro

Masahiro Yokotani

Izuru Shinjo

Naoki Hiraoka

A magnetic detection apparatus can accurately detect the rotational position of a magnetic moving member even when intervals between adjacent teeth formed thereon and the circumferential width of each tooth itself are both small and when an opposing distance between the magnetic moving member and first and second magnetoresistive segments is large. A processing circuit is arranged apart from the magnetic moving member on a plane thereof, which is formed on its periphery with the teeth. The processing circuit has a bridge circuit including the first magnetoresistive segment and the second magnetoresistive segment. A magnet applies a magnetic field to the first and second magnetoresistive segments, and to the magnetic moving member in a direction of an axis of rotation thereof. The second magnetoelectric conversion element is arranged substantially on a center line passing through the center of the magnet on a line in opposition to the magnetic moving member when viewed along the direction of the axis of rotation of the magnetic moving member, so that a differential output can be obtained from the outputs of the first magnetoelectric conversion element and the second magnetoelectric conversion element.

Magnetic detection apparatus

In a rotation angle detecting device, a circuit scale thereof is reduced and a manufacturing cost thereof is lowered. The rotation angle detecting device is arranged by comprising: a bridge circuit for converting a magnetic field change of an MR element into a voltage change; a 1st differential amplifying circuit for amplifying the signal outputted from the bridge circuit; an AC coupling circuit for removing a DC component from the output signal of the 1st differential amplifying circuit; a 2nd differential amplifying circuit for amplifying the signal output from the AC coupling circuit; a comparing circuit for comparing the signal outputted from the 2nd differential amplifying circuit with a reference value to thereby output any one of a signal of &ldquo;0&rdquo; and a signal of &ldquo;1&rdquo;; an output circuit for waveform-shaping the signal outputted from the comparing circuit; and an initiating circuit including a 1st to a 3rd transistors, and a differentiating circuit for driving the 1st to 3rd transistors; in which both the 1st and the 2nd transistors are connected to the AC coupling circuit so as to converge the output signal of the AC coupling circuit into a reference voltage immediately after a power supply is turned ON; and in which the 3rd transistor is connected to the comparing circuit so as to also converge the input signal of the comparing circuit into an AC coupling reference level.

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Tokyo, Japan

Naohiro Mishiro