MAGNETIC SENSOR

• Main Author: OMI TETSUYA
• Format: Patent
• Language: English; Japanese
• Published: 11.12.2014
• Subjects: ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVEREDIN A SINGLE OTHER SUBCLASS; MEASURING; MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES; MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR; PHYSICS; TARIFF METERING APPARATUS; TESTING

PROBLEM TO BE SOLVED: To provide a magnetic sensor capable of correcting an offset value of a waveform signal before rotation of a rotational element.SOLUTION: First, switches 21 and 22 are changed over so that a current flows from a power supply 40 to a ground 50 by way of a first ladder resistance circuit portion 25, a pair of magnetoresistive elements 23 and 24, and a second ladder resistance circuit portion 26 in this order, before rotation of a rotational element, thereby acquiring a first output value of a sensing unit 20 (Step 31). Next, the switches 21 and 22 are changed over so that a current flows from the power supply 40 to the ground 50 by way of the second ladder resistance portion 26, the pair of magnetoresistive elements 23 and 24, and the first ladder resistance circuit portion 25, thereby acquiring a second output value of the sensing unit 20 (Step 32). A differential value between the first output value and the second output value is acquired (Step 33). Thereafter, resistance values of the respective ladder resistance circuit portions 25 and 26 are changed so that the differential value is equal to an element sensitivity (Step 34). 【課題】回転体の回転前に波形信号のオフセット値を補正することができる磁気センサを提供する。【解決手段】まず、回転体の回転前に、電流が電源４０から第１ラダー抵抗回路部２５、一対の磁気抵抗素子２３、２４、及び第２ラダー抵抗回路部２６の順にグランド５０に流れるよう各スイッチ２１、２２を切り替え、センシング部２０の第１出力値を取得する（ステップ３１）。次に、電流が電源４０から第２ラダー抵抗回路部２６、一対の磁気抵抗素子２３、２４、及び第１ラダー抵抗回路部２５の順にグランド５０に流れるように各スイッチ２１、２２を切り替え、センシング部２０の第２出力値を取得する（ステップ３２）。続いて、第１出力値と第２出力値との差分値を取得する（ステップ３３）。この後、差分値が素子感度と等しくなるように、各ラダー抵抗回路部２５、２６の抵抗値をそれぞれ増減させる（ステップ３４）。【選択図】図１