Panasonic Intellectual Property Management Co., Ltd.

Panasonic Corporation

Takuya Tomida

Takeshi Uemura

Hideaki Fujiura

Ryo Osabe

Tadata Hatanaka

Shigeo Masai

A magnetic sensor includes a magneto-resistive element configured to output a signal and a detection circuit configured to receive the signal. The detection circuit includes a regulator configured to supply a potential to the magneto-resistive element, a first current path configured to electrically connect the magneto-resistive element to the regulator, a second current path, a switch, and a diagnostic circuit connected to the second current path. The second current path includes, and is configured to electrically connect the magneto-resistive element to the regulator via the resistor. The switch is configured to select one of the first current path and the second current path, and electrically connect the magneto-resistive element to the regulator via the selected one of the first current path and the second current path.

Rotation detecting device

A rotation detecting device includes first and second magnetic detection elements that output first and second signals and a detection circuit having the first and second signals input thereto. The detection circuit includes an automatic correction circuit that performs generating and updating of a correction value for correcting the and second signals. The automatic correction circuit is configured to stop the generating or the updating of the correction value in at least one of a case where a rotation direction of an object is changed to a reverse rotation direction from a normal rotation direction and a case where a rotation direction of the object is changed to the normal rotation direction from the reverse rotation direction.

Rotation detecting device and correction method therefor

A rotation detecting device is configured to be used with a switch and detect rotation of a rotation shaft having a magnetic body attached thereto. The rotation detecting device includes a magneto-resistive element facing the magnetic body and outputting a first signal related to displacement of the magnetic body, a Hall element facing the magnetic body and outputting a second signal related to displacement of the magnetic body, and a detection circuit having the first and second signals input thereto. The detection circuit is configured to: output the first signal while the switch is turned on; detect rotation-number information corresponding to the number of rotations of the rotation shaft based on the second signal at a first time point at which the switch is turned off; store the rotation-number information; and output the stored rotation-number information at a second time point when the switch is turned on after the first time point.

A rotation detecting device includes first to fourth magneto-resistive elements that are provided on a first substrate to constitute a bridge circuit, a detection circuit provided on a second substrate, first to fourth wirings each connecting between the detection circuit and respective one of ends of the first to fourth magneto-resistive elements, first to fourth nodes provided on the second substrate, and first and second amplifiers provided on the second substrate. The first node combines signals on the first and second wirings. The second node combines signals on the third and fourth wirings. The first and second amplifiers amplify signals at the first and second nodes, respectively.

The magnetic field detecting apparatus is provided with: a magnetic field detecting unit for outputting one of two signals having different potential levels from each other in response to a perpheral magnetic field; an energizing control unit for producing a periodic energizing control signal indicative of timing at which the magnetic field detecting unit is energized by employing a clock signal and another signal obtained by frequency-dividing, or frequency-multiplying the clock signal, and for supplying the produced energizing control signal to the magnetic field detecting unit; a first inverting unit for inverting the potential level of the output signal of the magnetic field detecting unit; and an energizing time period control unit for supplying a time period control signal to the energizing control unit, the time period control signal controlling the time period of the energizing control signal in response to the potential level of the output signal of the magnetic field detecting unit, and the potential level of the signal obtained by inverting the potential level of the output signal by the first inverting unit. The energizing time period control unit supplies any one of two pieces of the energizing control signals whose durations and time periods are different from each other, during which the magnetic field detecting unit is not energized, in response to the potential level of the time period control signal supplied from the energizing time period control unit.

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Kanagawa, Japan

Takuya Tomida