Direction detection apparatus

• US 4,429,469 A
• Filed: 11/12/1981
• Issued: 02/07/1984
• Est. Priority Date: 11/13/1980
• Status: Expired due to Term

• Current Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Tsushima, Noboru, Tomoyori, Makoto, Harumatsu, Masatoshi
• Primary Examiner(s): HAROIAN, HARRY
• Application Number:
  US06/320,523
• Time in Patent Office: 817 Days
• Field of Search: 33/361, 33/356, 33/357
• US Class Current: 33/361
• CPC Class Codes: G01C 17/30 Earth-inductor compasses

Abstract

A direction detection apparatus comprising a magnetic sensor which senses a geomagnetic azimuth, a turning-angle sensor which senses a turning angle dynamically, a magnetic-disturbance detector which detects a magnetic disturbance on the basis of the output of the magnetic sensor, and a signal switching device which transmits either the magnetic sensor output or the turning-angle sensor output to a display device in accordance with a signal from the magnetic-disturbance detector. The traveling direction of a moving object can be detected as a precise geographic azimuth even when the moving object lies in a place subject to the magnetic disturbance.

Claims

1. A direction detection apparatus for an automobile which includes a display means to show the direction of movement of the automobile, the direction apparatus further comprising a magnetic sensor means for sensing a geomagnetic azimuth and for producing an output signal in accordance with said azimuth, a turning-angle sensor means for dynamically sensing the turning angle of said automobile and producing an output signal in accordance with said turning angle, a magnetic-disturbance detector means for detecting a magnetic disturbance on the basis of the signal output of the said magnetic sensor means and producing a disturbance output signal upon said disturbance, and an automatic signal switching means for applying either the magnetic sensor means output signal or the turning-angle sensor means output signal to the said display device in accordance with said disturbance output signal from said magnetic-disturbance detector means.

2. A direction detection apparatus according to claim 1, and further comprising:

(a) means for comparing, at a sequence of fixed times, a resultant vector which is the product of a geomagnetism vector and a disturbing magnetism vector, with the immediately preceding resultant vector; and

, when said magnetic disturbance has been detected by the said comparing means,

(b) means for calculating the output of said turning-angle sensor to obtain a correct geographic azimuth by reference to the correct azimuth information which existed immediately before the magnetic disturbance detected by said magnetic sensor.

3. A direction detection apparatus according to claim 2, wherein when the absence of the magnetic disturbance has been detected by said comparing means in obtaining a geographic information based on the output of said turning-angle sensor means, the input azimuth information to said azimuth display device is again obtained from said magnetic sensor.

4. A direction detection apparatus according to claim 1, including means to correct a magnetic deviation so as to correct the azimuth information from said magnetic sensor means and thereby provide a correct geographic azimuth.

5. A direction detection apparatus according to claim 1, wherein said magnetic sensor means includes a flux-gate magnetic sensor head employing a toroidal core.