Electronic azimuth meter and timepiece

Geometrical instruments – Indicator of direction of force traversing natural media – Magnetic field responsive

Reexamination Certificate

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Details

C033S357000

Reexamination Certificate

active

06662459

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electronic azimuth meter (hereinafter, referred to also as “electronic compass”) having a magnetic detector including a magnetic sensor, further particularly to a method of adjusting (hereinafter, referred to also as “calibration” or “correction”) of an electronic azimuth meter and an apparatus used for carrying out the method.
2. Description of the Prior Art
According to a magnetic detector comprising a magnetic sensor (typically comprising a bridge circuit of an MR element) and an A/D converter, sensitivity (span of output) and offset of the detector differs for each detector and therefore, it is necessary to individually adjust an electronic azimuth meter having the magnetic detector under a magnetic field produced by a magnetic field generating apparatus.
In adjusting thereof, in order to synchronize the magnetic field generating apparatus with the magnetic detector of the electronic azimuth meter, a control unit of the magnetic field generating apparatus is electrically connected to the electronic azimuth meter by a wiring and a case back or a battery of the electronic azimuth meter is detached for the electric connection.
However, according to the electronic azimuth meter, there is a concern of changing an effective magnetic field applied to the magnetic sensor of the electronic azimuth meter by presence or absence of a battery or the case back and there is a concern that it is difficult to properly adjust the electronic azimuth meter.
SUMMARY OF THE INVENTION
The invention has been carried out in view of the above-described point and it is an object thereof to provide an adjusting method of an electronic azimuth meter capable of properly adjusting the electronic azimuth meter and an apparatus used for carrying out the method, that is, an electronic azimuth meter adjusting system, a magnetic field generating apparatus for the adjusting system and an electronic azimuth meter adjusted by the adjusting method.
In order to achieve the object, according to an aspect of the invention, there is provided a method of adjusting an electronic azimuth meter which is a method of adjusting an electronic azimuth meter having a magnetic detector, the method comprising the steps of generating magnetic fields including a magnetic field for starting to adjust the electronic azimuth meter at magnetic field generating means capable of generating a magnetic field stronger than the geomagnetism by an adjusting magnetic field generating sequence, arranging the electronic azimuth meter for acquiring output data of magnetic sensors by a data acquisition sequence for adjusting the electronic azimuth meter in correspondence with the magnetic field generating sequence in a magnetic field region produced by the magnetic field generating means by the magnetic field generating sequence, and starting the adjusting data acquisition sequence of the electronic azimuth meter by sensing the strong magnetic field for starting to adjust the electronic azimuth meter by the magnetic detector.
According to the method of adjusting an electronic azimuth meter of the invention, since “the strong magnetic field for starting to adjust the electronic azimuth meter is generated by the magnetic field generating means and the sequence of acquiring data for adjusting the electronic azimuth meter is started by the strong magnetic field for starting to adjust the electronic azimuth meter”, by only generating the strong magnetic field for starting to adjust the electronic azimuth meter by the magnetic field generating means, the sequence of acquiring data for adjusting the electronic azimuth meter can be started. Further, according to the method of adjusting an electronic azimuth meter of the invention, since “the magnetic field generating means generates the magnetic field by the sequence of generating the magnetic field for adjusting the electronic azimuth meter and the electronic azimuth meter for acquiring output data of the magnetic detector by the sequence of acquiring data for adjusting the electronic azimuth meter in correspondence with the sequence of generating the magnetic field, is arranged in the magnetic field region produced by the magnetic field generating means by the magnetic field generating sequence”, after starting the adjusting data acquisition sequence of the electronic azimuth meter, the electronic azimuth meter can acquire, as adjusting data, output data of the magnetic detector by the adjusting data acquisition sequence in correspondence with the magnetic field generating sequence under the magnetic field produced by the adjusting magnetic field generating sequence by the magnetic field generating means. That is, the magnetic field generating means generates the magnetic field for adjustment by itself by the adjusting magnetic field generating sequence and the electronic azimuth meter acquires output data (data for adjustment) of the magnetic detector by itself by the adjusting data acquiring sequence. The adjusting data acquiring sequence is previously adjusted to progress in correspondence with the adjusting magnetic field generating sequence and the two sequences are started actually simultaneously by generating the magnetic field for starting the adjustment and detecting the subject magnetic field. Therefore, even when a control unit of the magnetic field generating means and the electronic azimuth meter are not electrically connected by a wiring, the two sequences can be progressed at actually the same or corresponding timing with the magnetic field as a medium. As a result, the electronic azimuth meter can be adjusted by progressing the two sequences actually similar to the case of adjusting the electronic azimuth meter by exchanging synchronizing signals between the control unit of the magnetic field generating means and the electronic azimuth meter. Further, electric wiring connection is dispensed with between the control unit of the magnetic field generating means and the electronic azimuth meter and therefore, it is not necessary to detach a battery or a case back in the adjustment, the electronic azimuth meter can be adjusted while maintaining the electronic azimuth meter in a mode of a finished product actually used and therefore, the electronic azimuth meter can properly be adjusted by avoiding a concern of causing error derived from presence or absence of the battery or the case back in the adjustment.
In the specification, a technical term of “magnetic field” is used to define “magnetic flux density” unless specified otherwise and a case of designating inherently “magnetic flux density” is referred to as “magnetic field”. In designation thereof, not H but B is used. Further, in the specification, strong magnetic field signifies a magnetic field stronger than a magnetic field by the geomagnetism (about several &mgr;T (micro tesla) and “strong” designates a magnetic field which can be differentiated from the magnetic field by the geomagnetism owing to the intensity of the magnetic field. Therefore, for example, the strong magnetic field designates a magnetic field several times as much as or more than the geomagnetism, preferably, about ten times or more thereof, typically about 100 &mgr;T. Naturally, further stronger magnetic field may be used, however, in order to minimize a concern of strongly magnetizing a magnetic part of an electronic azimuth meter, it is preferable that the magnetic field is not strong excessively. Further, in the specification, unless specified otherwise, azimuth or azimuth angle is represented by notation &phgr;, north is represented by 0 degree, east is represented by 90 degree, south is represented by 180 degree and west is represented by 270 degree. The geographical azimuth angle is represented by notation &thgr; and is described as display azimuth angle. Further, &phgr;+&thgr;=360°.
The adjusting magnetic field generating sequence typically includes four azimuth magnetic fields generating steps for successively generating magnetic fields of four azimuths. B

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