US 4,402,142 AGranted

Electronic compass for automotive vehicles

OwnerRobert C. Dinsmoreinventor

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Abstract

An electronic compass for vehicles such as automobiles comprising a float mechanism including a permanent magnet for following the earth's magnetic field and four Hall effect sensors for detecting magnet orientation at points corresponding to the cardinal compass points. The Hall effect sensors are connected to triggering circuits having overlapping thresholds so that two circumferentially adjacent sensors and sensor trigger circuits cooperate to indicate not only the corresponding cardinal compass points but also the secondary compass point intermediate the cardinal points. The sensor trigger circuitry is connected to a two-character multiple-segment display for indicating vehicle orientation at either one of the four cardinal compass points or one of the four secondary compass points intermediate successive cardinal points. Circuitry for compensating for variations in the earth's magnetic field caused by the vehicle comprises a pair of electromagnetic coils having perpendicular axes which perpendicularly intersect the axis of float rotation and variable resistors coupled to the coils for varying the magnetic compensation field generated by each coil independently of the other.

A compass for vehicles such as automobiles and the like comprising first means adapted for fixed disposition with respect to said vehicle and second means adapted for movement with respect to said first means for following the earth's magnetic field, sensing means responsive to relative positions of said first and second means for indicating orientation of said vehicle with respect to the earth's magnetic field, and means responsive to said sensing means for displaying said orientation including two-character display means for displaying said orientation as one of the characters "N", "E", "S" and "W" indicative of the cardinal compass points and as two-character combinations of said characters indicative of secondary compass points intermediate successive ones of said cardinal compass points,

said two character display means comprising a multiple-aperture light pipe in which the first display character is a multiple-segment character defined by six linear segment apertures disposed in a first rectangular pattern having two segment apertures on each side and one segment aperture on each end, a seventh segment aperture extending across said first rectangular pattern between said two segment apertures on each side of said first rectangular pattern, and eighth and ninth segment apertures extending diagonally across said first rectangular pattern, and the second character is a multiple-segment character defined by six linear segment apertures disposed in a second rectangular pattern laterally adjacent to said first rectangular pattern and having two segment apertures on each side and one segment aperture on each end, a seventh segment aperture extending across said second rectangular pattern between said two segment apertures on each side of said second rectangular pattern, eighth and ninth segment apertures extending in an inverted V-shaped pattern between lower corners of said second rectangular pattern,
said first through said seventh segments of said first display character being identical to said first through said seventh segments of said second display character,
said two character display means further comprising eighteen individually selectable light emitting means disposed one in association with each said aperture for selectively and alternately indicating at said first display character the letters "N" and "S" and for selectively and alternately indicating at said second display character the letters "E" and "W".

Abstract

Claims7