Electronic azimuth meter, correcting mechanism for electronic azimuth meter, and electronic timepiece having electronic azimuth meter

• US 6,768,957 B2
• Filed: 04/18/2001
• Issued: 07/27/2004
• Est. Priority Date: 05/12/2000
• Status: Active Grant

• Current Assignee: Seiko Instruments Incorporated (Seiko Group)
• Original Assignee: Seiko Instruments Incorporated (Seiko Group)
• Inventors: Kato, Kazuo
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): Cherry, Stephen J.
• Application Number:
  US09/837,840
• Publication Number:
  US 20010042314A1
• Time in Patent Office: 1,196 Days
• Field of Search: 702/92, 333/56, 333/55.R, 73/17.6
• US Class Current: 702/92
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses

Abstract

A correcting mechanism for an electronic azimuth meter has an X-direction magnetic sensor and a Y-direction magnetic sensor for detecting a magnetic field in two orthogonal directions X and Y and for calculating an azimuth of a main body of an electronic azimuth meter. An azimuth change inducing unit provides a display of an induction mark to induce a continuous change of the azimuth of the electronic azimuth meter main body over a range of rotation of at least 360 degrees.

Claims

1. A correcting mechanism for an electronic azimuth meter, the correcting mechanism comprising:

an X-direction magnetic sensor and a Y-direction magnetic sensor for detecting intensities of a magnetic field in two orthogonal directions X and Y and for calculating an azimuth of a main body of an electronic azimuth meter in accordance with magnetic field intensity values from the X- and the Y-direction magnetic sensors;

storing means for storing a maximum value and a minimum value of the magnetic field detected by each of the X-direction and the Y-direction magnetic sensors;

updating means for updating the maximum value or the minimum value of the magnetic field when the value of the magnetic field detected by each of the X-direction and the Y-direction magnetic sensors is larger than the maximum value stored in the storing means or smaller than the minimum value stored in the storing means;

azimuth changing means for providing a display of an induction mark to induce a continuous change of the azimuth of the electronic azimuth meter main body over a range of rotation larger than 360 degrees;

predicting means for predicting that the maximum value or the minimum value of the magnetic field in the X- or Y-direction is a true value when each of the maximum values and the minimum values of the magnetic field values in the X-direction and the Y-direction is not updated during a predetermined time period in accordance with rotation of the electronic azimuth meter main body and in accordance with a display of the induction mark by the azimuth changing means, and for canceling a prediction indicating the true value when the maximum value or the minimum value predicted to be the true value is updated by the updating means; and

stop control means for controlling the updating means to stop updating when all of the maximum values and the minimum values in the X-direction and the Y-direction are predicted to be the true values and when the change of the azimuth of the electronic azimuth main body reaches 360 degree or more.

2. A correcting mechanism according to claim 1;

wherein the stop control means includes means for stopping the display of the induction mark when the updating means stops updating.

3. An electronic azimuth meter having the correcting mechanism according to claim 2.

4. An electronic timepiece having the electronic azimuth meter according to claim 3.

5. An electronic azimuth meter having the correcting mechanism according to claim 1.

6. An electronic timepiece having the electronic azimuth meter according to claim 5.

7. A correcting mechanism for an electronic azimuth meter, the correcting mechanism comprising:

an X-direction magnetic sensor and a Y-direction magnetic sensor for detecting a magnetic field in two orthogonal directions X and Y and for calculating an azimuth of a main body of an electronic azimuth meter; and

azimuth changing means for providing a display of an induction mark to induce a continuous change of the azimuth of the electronic azimuth meter main body over a range of rotation larger than 360 degrees.

8. A correcting mechanism according to claim 7, further comprising updating means for updating a maximum value or a minimum value of the magnetic field detected by the X-direction and the Y-direction sensors to a newly detected magnetic field value when the newly detected magnetic field value is larger than the maximum value or smaller than the minimum value of the magnetic field;

predicting means for predicting that the maximum value or the minimum value of the magnetic field in the X- or Y-direction is a true value when the maximum value or the minimum value of the magnetic field in each of the X-direction and the Y-direction is not updated during a predetermined time period in accordance with rotation of the electronic azimuth meter main body and in accordance with a display of the induction mark by the azimuth changing means, and for canceling a prediction indicating the true value when the maximum value or the minimum value predicted to be the true value is updated; and

stop control means for controlling the updating means to stop updating when all of the maximum values and the minimum values in the X-direction and the Y-direction are predicted to be the true values and when the azimuth change is displayed over a range of 360 degrees or more.

9. A correcting mechanism according to claim 8;

wherein the stop control means includes means for stopping the display of the induction mark when the updating means stops updating.

10. An electronic azimuth meter having the correcting mechanism according to claim 9.

11. An electronic timepiece having the electronic azimuth meter according to claim 10.

12. An electronic azimuth meter having the correcting mechanism according to claim 8.

13. An electronic timepiece having the electronic azimuth meter according to claim 12.

14. An electronic azimuth meter having the correcting mechanism according to claim 7.

15. An electronic timepiece having the electronic azimuth meter according to claim 14.

16. A correcting mechanism for an electronic azimuth meter, the correcting mechanism comprising:

detecting means for detecting intensities of a magnetic field in two orthogonal directions;

calculating means for calculating an azimuth of a main body of an electronic azimuth meter in accordance with a value of the magnetic field detected by the detecting means;

updating means for updating a maximum value or a minimum value of the magnetic field to a newly detected magnetic field value when the newly detected magnetic field value is larger than a given maximum value or smaller than a given minimum value;

azimuth changing means for providing a rotational display of an induction mark to induce a continuous change of the azimuth of the electronic azimuth meter main body over a range of rotation of at least 360 degrees;

determining means for determining whether the electronic azimuth meter main body has been rotated by at least 360 degrees in accordance with the rotational display of the induction mark; and

stop control means for controlling the updating means to stop updating the maximum or minimum value of the magnetic field when the determining means determines that the electronic azimuth meter main body has been rotated by at least 360 degrees.

17. An electronic azimuth meter having the correcting mechanism according to claim 16.

18. An electronic timepiece having the electronic azimuth meter according to claim 17.