Magnetism detection device and magnetism detection method
AssigneeAsahi Kasei Microdevices Corporation
InventorTakeo Yamamoto
Life of this patent
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Abstract
The present invention relates to a magnetism detection device. First and second switch units switch a direction of a current flown from a bias generating unit across two opposite terminals of four terminals of a hall sensor, and switch a direction of a voltage to be available in remaining two opposite terminals in the direction orthogonal to the direction of the current, respectively, so that in a first period, a polarity of a hall electromotive force is a first polarity and a polarity of the hall offset voltage alternates four times, and in a second period, the polarity of the hall electromotive force is a second polarity opposite to the first polarity and the polarity of the hall offset voltage alternates four times.
Claims6
A magnetism detection device comprising:
- a hall sensor that detects magnetism;
- a bias generating unit that drives the hall sensor;
- a switch unit that is connected to the hall sensor, that carries out a switch operation of switching a direction of current flown from the bias generating unit across two opposite terminals of four terminals of the hall sensor, and switching the direction of a voltage to be available in remaining two opposite terminals in a direction orthogonal to the direction of the current, so that in a first period, a polarity of a hall electromotive force of the hall sensor is a first polarity and a polarity of the hall offset voltage of the hall sensor alternates four times, and in a second period, the polarity of the hall electromotive force of the hall sensor is a second polarity opposite to the first polarity and the polarity of the hall offset voltage of the hall sensor alternates four times;
- an amplifier that amplifies the voltage made available by the switch operation of the switch unit;
- and
- a reversing unit that reverses the polarity of the voltage from the amplifier in synchronization with the switching operation between the first period and the second period out of switching operations of the current and the voltage switched by the switch unit.
A magnetism detection device comprising:
- a hall sensor that detects magnetism;
- a bias generating unit that drives the hall sensor;
- a switch unit that carries out a switch operation of switching a direction of a current flown from the bias generating unit across two opposite terminals of four terminals of the hall sensor, and that carries out a switch operation of switching a direction of a voltage to be available in remaining two opposite terminals in a direction orthogonal to the direction of the current, respectively;
- an amplifier that amplifies the voltage made available by the switch operation of the switch unit;
- and
- a reversing unit that reverses a polarity of voltage from the amplifier,
- wherein an operation frequency when a polarity of a hall offset voltage of the hall sensor alternates is 2n times the operation frequency when a polarity of a hall electromotive force of the hall sensor alternates, where n is an integer equal to or greater than 1.
A magnetism detection method in a magnetism detection device comprising a hall sensor that detects magnetism and a bias generating unit that drives the hall sensor, the magnetism detection method comprising:
- carrying out, by a switch unit connected to the hall sensor, a switch operation of switching a direction of a current flown across two opposite terminals of four terminals of the hall sensor, and switching a direction of a voltage to be available in remaining two opposite terminals in a direction orthogonal to the direction of the current, respectively, so that in a first period, a polarity of a hall electromotive force of the hall sensor is a first polarity and a polarity of a hall offset voltage of the hall sensor alternates four times;
- carrying out, by the switch unit connected to the hall sensor, a switch operation of switching the direction of the current flown across the two opposite terminals of the four terminals of the hall sensor, and switching the direction of the voltage to be available in the remaining two opposite terminals in the direction orthogonal to the direction of the current, so that in a second period, the polarity of the hall electromotive force of the hall sensor is a second polarity opposite to the first polarity and the polarity of the hall offset voltage alternates four times;
- amplifying, by an amplifier, the voltage made available by the switch operation of the switch unit;
- and
- reversing, by a reversing unit, a polarity of the amplified voltage in synchronization with the switch operation between the first period and the second period out of the switch operations of switching the current and the voltage by the switch unit.
Dependencies are inferred from the claim text.