Remote indicating solid state magnetic sensor

• US 4,030,204 A
• Filed: 03/18/1974
• Issued: 06/21/1977
• Est. Priority Date: 03/18/1974
• Status: Expired due to Term

• Current Assignee: Robert A. Edwards
• Original Assignee: Robert A. Edwards
• Inventors: Edwards, Robert A.
• Primary Examiner(s): Martin, Jr., William D.
• Application Number:
  US05/452,430
• Time in Patent Office: 1,191 Days
• Field of Search: 33/355, 33/357, 33/558, 33/361, 33/363, 324/45, 324/44
• US Class Current: 33/361
• CPC Class Codes: G01C 17/28 Electromagnetic compasses with north seeking magnetic elements and having electric pick-offs G01C17/26
• CPC Class Codes: G01C 17/36 Repeaters for remote indication of readings of a master compass

Abstract

A solid state magnetic sensor system for indicating the direction of an applied magnetic field and more specifically as a compass system for use with automobiles or the like. The system consists of a dashboard mounted readout unit which receives signals provided thereto from a remotely located solid state magnetic bearing sensor, the latter being responsive to the earth'"'"'s magnetic field. The solid state magnetic bearing sensor described herein, includes a pair of Hall effect semiconductors and ancillary electronic circuits. Two ancillary circuit types are described. One circuit is designed to output digital codes indicative of magnetic heading; the other circuit is designed to output two currents which are indicative of sine and cosine components of magnetic heading. The circuit designed to output digital codes includes sinusoidal waveform generators, a binary counter, a differential comparator amplifier and digital latch and decoding circuits. The circuit designed to output currents indicative of sine and cosine components of magnetic heading are comprised of a pair of linear differential buffer amplifiers. The dashboard mounted readout unit designed to accept digital codes may be defined by a plurality of discrete indicators, such as light emitting diodes, or segmented alpha indicators or so forth may be employed. The dashboard mounted readout unit designed to accept two currents which are indicative of sine and cosine components of magnetic heading may be characterized as a pointer which is pivoted about an axle by the influence of the magnetic field induced by a surrounding stator whose windings receive the aforementioned two currents. The solid state sensor unit is preferably located at a point on the vehicle distant from large bodies of iron or steel and where the earth'"'"'s field is strong relative to fields associated with permanently magnetized auto parts.

Claims

1. A low-inertia remote-indicating magnetic compass utilizing a solid-state magnetic sensor and providing a continuous 360°

read-out meter movement for use in automobiles or the like and comprising;

a magnetic sensor consisting of a pair of Hall generators mounted to a vehicle in vertical planes, at right angles to one another, with one of two corresponding pairs of each generator'"'"'s parallel edges connected across a source of d-c voltage, and with the remaining two parallel pairs of edges connected to the inputs of linear amplifiers to amplify Hall voltages, proportional to sine and cosine components of the earth'"'"'s magnetic field, and with adjustable compensation magnets in the vicinity of said generators to cancel spurious magnetic fields of said automobile;

an indicator consisting of a stator with quadrature windings connected to outputs of said linear amplifiers, a magnetized rotor-pointer which pivots about the stator'"'"'s principal axis in response to currents in stator windings, and a circular compass scale, centered with respect to the rotor'"'"'s pivot axis, rotor position ranging through 360° and

determined by relative magnitudes of quadrature winding currents, pointer-position relative to map scale indicative of vehicle heading.