Abstract: An X-axis sensor, a Y-axis sensor, and a Z-axis sensor that detect a geomagnetic vector are provided, and the direction of the geomagnetic vector is sought on a spherical coordinate from the detection output of each sensor. A reference axis is determined in the spherical coordinate, a hypothetical central point is sought on the reference axis depending on data of two coordinate detection points, a perpendicular line to a plane that includes vectors from the hypothetical central point to the respective data is sought from the cross product of the vectors, an axis that is parallel to the perpendicular line and passes through an origin is set to be a calculated rotational axis, and movement centered around the calculated rotational axis is specified.

Abstract: An azimuth calculation program is a computer-executable program that performs an azimuth calculation using output of a magnetic sensor. The azimuth calculation program includes a first step of generating one triangle in three-dimensional space using three output values of a magnetic sensor unit, a second step of determining a circumcircle of the triangle, and a third step of performing an azimuth calculation using center coordinates of the circumcircle and output values of the magnetic sensor.

Abstract: A constant-voltage circuit includes a first reference voltage generation unit which generates a reference voltage using a bandgap voltage of a bipolar transistor, a second reference voltage generation unit which generates a reference voltage using a field effect transistor, a constant voltage generation unit which generates a constant voltage with reference to either an output voltage of the first reference voltage generation unit or an output voltage of the second reference voltage generation unit, and a control unit which controls the first reference voltage generation unit, the second reference voltage generation unit, and the constant voltage generation unit. During an initial activation period, the first reference voltage generation unit and the second reference voltage generation unit are operated, and during a subsequent operation period, the first reference voltage generation unit is stopped.

Abstract: A constant-voltage circuit includes a first reference voltage generation unit which generates a reference voltage using a bandgap voltage of a bipolar transistor, a second reference voltage generation unit which generates a reference voltage using a field effect transistor, a constant voltage generation unit which generates a constant voltage with reference to either an output voltage of the first reference voltage generation unit or an output voltage of the second reference voltage generation unit, and a control unit which controls the first reference voltage generation unit, the second reference voltage generation unit, and the constant voltage generation unit. During an initial activation period, the first reference voltage generation unit and the second reference voltage generation unit are operated, and during a subsequent operation period, the first reference voltage generation unit is stopped.

Abstract: An X-axis sensor, a Y-axis sensor, and a Z-axis sensor that detect a geomagnetic vector are provided, and the direction of the geomagnetic vector is sought on a spherical coordinate from the detection output of each sensor. A reference axis is determined in the spherical coordinate, a hypothetical central point is sought on the reference axis depending on data of two coordinate detection points, a perpendicular line to a plane that includes vectors from the hypothetical central point to the respective data is sought from the cross product of the vectors, an axis that is parallel to the perpendicular line and passes through an origin is set to be a calculated rotational axis, and movement centered around the calculated rotational axis is specified.

Abstract: A controller includes a calibration unit, an offset error correcting unit, an operation unit, and the like. The calibration unit obtains a reference point of an output of a magnetic sensor, and performs offset correction. The offset error correcting unit is capable of performing operation processing for both the correction of a major offset error and the correction of a minor offset error by using a radius (the magnitude of a geomagnetic vector) of a virtual circle or a virtual sphere, appropriately and easily correcting the offset error with a small amount of operation, and reducing the burden to the controller.

Abstract: A motion sensing program for executing a motion sensing based on at least a biaxial output of a magnetic sensor, which includes the steps of determining with respect to execution of the motion sensing based on the output of the specific biaxial output of the magnetic sensor upon its rotation in a predetermined direction, and identifying the rotating direction when execution of the motion sensing is determined.

Abstract: A geomagnetic sensor control device includes an analog circuit unit that outputs a plurality of magnetic field measurement values corresponding to sensor output signals of a plurality of magnetic sensors, and a digital circuit unit that receives three-axis magnetic field measurement values from the analog circuit unit and that performs digital processing. In the analog circuit unit, offset correction is performed in an analog manner on an offset included in a sensor output signal. In the digital circuit unit, sensitivity correction is performed in a digital manner on a magnetic field measurement value corresponding to the sensor output signal on which the offset correction has been performed.

Abstract: An azimuth computing device includes an azimuth computing unit for computing azimuth data by using an output from a magnetic sensor; a buffer unit for storing the azimuth data; a control unit for outputting azimuth data if the azimuth data stored in the buffer unit by a predetermined number of pieces is within a predetermined range; and a storage unit for storing the output azimuth data as a reference azimuth. The control unit outputs azimuth data if the azimuth data stored in the buffer unit is within a predetermined angle from the reference azimuth, and discards at least part of the azimuth data stored in the buffer unit if the azimuth data stored in the buffer unit is not within the predetermined range.

Abstract: The object of the present invention is to provide a calibration program and an electronic compass that make it possible to calibrate the output of a magnetic sensor with a small amount of computation while a user does not notice the execution of calibration. A calibration program according to an aspect of the invention includes: a step of forming at least two triangles 21 and 22 with the use of at least four outputs of a magnetic sensor in a three-dimensional space; a step of finding circles 23 and 24 circumscribed about the triangle 21 and 22, respectively; and a step of finding the intersection of normal vectors 25 and 26 each of which passes through the center of the corresponding circumscribed circle so as to find a reference point.

Abstract: An azimuth calculation program is a computer-executable program that performs an azimuth calculation using output of a magnetic sensor. The azimuth calculation program includes a first step of generating one triangle in three-dimensional space using three output values of a magnetic sensor unit, a second step of determining a circumcircle of the triangle, and a third step of performing an azimuth calculation using center coordinates of the circumcircle and output values of the magnetic sensor.

Abstract: A motion sensing program for executing a motion sensing based on at least a biaxial output of a magnetic sensor, which includes the steps of determining with respect to execution of the motion sensing based on the output of the specific biaxial output of the magnetic sensor upon its rotation in a predetermined direction, and identifying the rotating direction when execution of the motion sensing is determined.

Abstract: The object of the present invention is to provide a calibration program and an electronic compass that make it possible to calibrate the output of a magnetic sensor with a small amount of computation while a user does not notice the execution of calibration. A calibration program according to an aspect of the invention includes: a step of forming at least two triangles 21 and 22 with the use of at least four outputs of a magnetic sensor in a three-dimensional space; a step of finding circles 23 and 24 circumscribed about the triangle 21 and 22, respectively; and a step of finding the intersection of normal vectors 25 and 26 each of which passes through the center of the corresponding circumscribed circle so as to find a reference point.

Abstract: When an external magnetic field is applied to a sensor unit 12 for various causes, a characteristics curve does not pass through an intersection point of resistance (voltage) and a magnetic field and is offset. That is, an offset voltage (Roff) occurs. In the present invention, in order to determine a correction value for canceling the offset voltage, a difference between output voltages is determined from two stages in which a bias magnetic field is inverted, and the bias magnetic field is controlled until the difference becomes approximately zero. Then, the corresponding bias magnetic field (the electrical current value) when the difference between the output voltages becomes approximately zero is set as a correction value (correction bias). As a result, since correction can be performed even if an offset voltage is applied, it is possible to accurately perform magnetic detection.