Portable electronic apparatus with azimuth measuring function, magnetic sensor suitable for the apparatus, and azimuth measuring method for the apparatus

• US 20070111765A1
• Filed: 01/05/2007
• Published: 05/17/2007
• Est. Priority Date: 07/10/2001
• Status: Abandoned Application

• Current Assignee: Yamaha Corporation
• Original Assignee: Yamaha Corporation
• Inventors: Sato, Hideki
• Application Number:
  US11/649,778
• Publication Number:
  US 20070111765A1
• Time in Patent Office: Days
• US Class Current: 455/575.100
• CPC Class Codes: G01C 17/28 Electromagnetic compasses with north seeking magnetic elements and having electric pick-offs G01C17/26
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses
• CPC Class Codes: H04M 1/21 Combinations with auxiliary equipment, e.g. with clocks or memoranda pads
• CPC Class Codes: H04M 1/72403 with means for local support of applications that increase the functionality
• CPC Class Codes: H04M 2250/12 including a sensor for measuring a physical value, e.g. temperature or motion telephones including GPS signal receivers H04M2250/10

Abstract

A portable phone has a CPU and a magnetic sensor unit including an X-axis magnetic sensor, a Y-axis magnetic sensor, and a temperature sensor. CPU measures at first and second temperatures the influence of a magnetic field of permanent magnets upon an output Sx of the X-axis magnetic sensor and an output Sy of the Y-axis magnetic sensor, and stores the influence data together with the first and second temperature data. CPU estimates at the present temperature the influence upon the output Sx of the X-axis magnetic sensor and the output Sy of the Y-axis magnetic sensor, from the present temperature detected with the temperature sensor and the stored influence data. CPU corrects the outputs Sx and Sy in accordance with the estimated influence and determines the direction of the portable phone from the corrected outputs Sx and Sy.

Claims

1. A portable electronic apparatus comprising:

a casing;

a communication device accommodated in said casing and having permanent magnets; and

a direction measuring device accommodated in said casing for measuring a direction by utilizing geomagnetism, wherein said direction measuring device comprises;

magnetic sensors for outputting signals corresponding to an external magnetic field,

a temperature sensor for detecting a temperature,

a corrector for estimating influence of the magnetic field of the permanent magnets upon the signals output from said magnetic sensors in accordance with the detected temperature, and correcting the signals output from said magnetic sensors in accordance with the estimated influence, wherein said corrector;

measures at a first temperature the influence of the magnetic field of the permanent magnets contained in the signals output from said magnetic sensors,

measures at a second temperature different from the first temperature the influence of the magnetic field of the permanent magnets contained in the signals output from said magnetic sensors, and

estimates the influence of the magnetic field of the permanent magnets from the influence at the first temperature the influence at the second temperature, and a present temperature detected with said temperature sensor; and

a direction determining device for determining a direction in accordance with the corrected signals.

2. The portable electronic apparatus according to claim 1, wherein said casing has a first plane, and the portable electronic apparatus further comprises an input device formed on the first plane for inputting an operation signal.

3. The portable electronic apparatus according to claim 1, wherein said communication device includes a speaker.

4. The portable electronic apparatus according to claim 1, wherein said communication device includes a microphone.

8. The portable electronic apparatus according to claim 1, wherein the corrector performs linear interpolation using the first temperature, the second temperature, and the present temperature of the permanent magnets.

9. The portable electronic apparatus according to claim 1, wherein the difference between the first temperature and the second temperature is 5°

C. to 25°

C.

10. The portable electronic apparatus according to claim 1, wherein the magnetic sensors and the temperature sensor are on a single chip.

11. The portable electronic apparatus according to claim 1, wherein the magnetic sensors and the temperature sensor are connected to one analog to digital converter.

5. (canceled)

6. A direction measuring method comprising:

preparing a portable electronic apparatus comprising a casing having a first plane, a communication device accommodated in the casing and having permanent magnets, magnetic sensors accommodated in the casing and outputting signals corresponding to an external magnetic field, and an input device formed on the first plane for inputting an operation signal;

measuring signals output from the magnetic sensors as first values when the operation signal is input, in a state that the first plane of the portable electronic apparatus is turned upside;

measuring signals output from the magnetic sensors as second values when the operation signal is input, in a state that the first plane of the portable electronic apparatus is turned upside and the portable electronic apparatus is rotated by 180°

after the first values are measured;

estimating offset amounts that indicate an influence of a magnetic field by the permanent magnets upon the signals output from the magnetic sensors in accordance with the first and second values, wherein said estimating also considers a temperature of the permanent magnets;

correcting the signals output from the magnetic sensors in accordance with the estimated offset amounts of the influence of the magnetic field by the permanent magnets; and

determining a direction in accordance with the corrected signals of the magnetic sensors.

12. A direction measuring method according to claim 6, wherein said correcting comprises:

measuring at a first temperature the influence of the magnetic field of the permanent magnets contained in the signals output from said magnetic sensors,

measuring at a second temperature different from the first temperature the influence of the magnetic field of the permanent magnets contained in the signals output from said magnetic sensors, and

estimating the influence of the magnetic field of the permanent magnets from the influence at the first temperature, the influence at the second temperature, and a present temperature detected with said temperature sensor.

13. The direction measuring method according to claim 12, further comprising:

performing linear interpolation using the first temperature, the second temperature, and the present temperature of the permanent magnets.

14. The direction measuring method according to claim 13, wherein the differences between the first temperature and the second temperature is 5°

C. to 25°

C.

7. (canceled)

15. An azimuth measuring apparatus comprising:

a casing;

a permanent magnetic component contained in said casing; and

an azimuth measuring device accommodated in said casing for measuring a direction by utilizing geomagnetism, wherein said azimuth measuring device comprises;

magnetic sensors for outputting signals corresponding to an external magnetic field,

a temperature sensor for detecting a temperature,

a corrector for estimating influence of the magnetic field of the permanent magnets upon the signals output from said magnetic sensors in accordance with the detected temperature, and correcting the signals output from said magnetic sensors in accordance with the estimated influence, wherein said corrector;

measures at a first temperature the influence of the magnetic field of the permanent magnets contained in the signals output from said magnetic sensors,

measures at a second temperature different from the first temperature the influence of the magnetic field of the permanent magnets contained in the signals output from said magnetic sensors, and

estimates the influence of the magnetic field of the permanent magnets from the influence at the first temperature, the influence at the second temperature, and a present temperature detected with said temperature sensor; and

an azimuth determining device for determining a direction in accordance with the corrected signals.