Internally gimballed compass

Claim 2

A magnetic compass comprising: a first housing; a compass card having indicia on a surface thereof representative of compass heading; a second housing affixed to said compass card and rotatably mounted in said first housing for rotation about the axis of said compass card; at least one magnet coupled to said compass card and having a magnetic axis orthogonal to one rotational axis thereof; and a gimbal assembly supported within said second housing and operative to suport said at least one magnet for independent rotation throughout 360* about orthogonal axes transverse to the axis of said compass card.

Claim 3

A magnetic compass according to claim 1 wherein said at least one magnet includes counterweight means affixed thereto and operative to maintain the magnetic axis thereof in substantially horizontal disposition during normal operation.

Claim 4

A magnetic compass according to claim 1 wherein said gimbal assembly includes a support frame having first and second mounting pins supported by said second housing and defining a first transverse axis about which said at least one magnet is moveable; and third and fourth support pins affixed to said frame and supporting said at least one magnet within said frame for rotation about a second transverse axis defined by said third and fourth pins, said second axis being orthogonal to said first axis.

Claim 5

A magnetic Compass according to claim 3 wherein said mounting means includes bearing means affixed to said housings and operative to support said compass card and said second housing for rotation about the axis of said card.

Claim 6

A magnetic compass comprising: a first cylindrical housing having a top and a bottom wall each having centrally disposed bearing support means; a second cylindrical housing coaxially disposed inside said first housing and having a top and a bottom wall each having centrally disposed bearing means cooperative with said first housing bearing support means to define upper and lower pivot bearings for pivotal support of said second housing for rotation about the axis of said first housing; a cup-shaped member disposed within said second housing; a gimbal frame attached to said cup-shaped member for 360* rotation about a first axis orthogonal to said housing axis; a cylindrical magnet attached to said gimbal frame for 360* rotation about a second axis orthogonal to said first axis; a compass card affixed to the top wall of said second housing for rotation therewith; code indicia on said compass card representative of compass headings; and code sensing means disposed in operative relation to said indicia and operative to provide electrical output signals in response to sensed indicia indicative of compass heading.

Claim 7

A magnetic compass comprising: a first cylindrical housing having a top and a bottom wall each having centrally disposed bearing support means; a second cylindrical housing coaxially disposed inside said first housing and having a top and a bottom wall each having centrally disposed bearing means cooperative with said first housing bearing support means to define upper and lower pivot bearings for pivotal support of said second housing for rotation about the axis of said first housing; a cup-shaped member disposed within said second housing; a gimbal frame attached to said cup-shaped member for 360* rotation about a first axis orthogonal to said housing axis; a cylindrical magnet attached to said gimbal frame for 360* rotation about a second axis orthogonal to said first axis; a compass card affixed to the top wall of said second housing for rotation therewith; code indicia on said compass card representative of compass headings; and code sensing means disposed in operative relation to said indicia and operative to provide electrical output signals in response to sensed indicia indicative of compass heading.

Claim 8

A digital compass according to claim 5 wherein said compass card includes; an optically sensible disk having a plurality of concentric tracks on a surface thereof each with a different number of alternately light transmissive and opaque segments defining a plurality of multiple bit coded values representative of compass headings; and wherein said code sensing means includes; a light source in said first housing for transmitting light through the plurality of tracks of said disk; a plurality of photosensors in said first housing and each operative to receive light from a respective track of said disk and to produce a corresponding digital signal; a circuit board supported on the top wall of said first housing and containing circuitry coupled to said plurality of photosensors and operative to provide in response to said digital signals an output signal representative of compass heading; and means for coupling said output signal to utilization means.

Claim 9

A magnetic compass according to claim 5 wherein said upper pivot bearing includes; a cylindrical fitting mounted in the top wall of said housing and aligned with the axis of said first housing; a pivot bearing element mounted in said fitting in alignment with said housing axis and having a downwardly disposed pivot bearing receptacle; a post mounted on the top wall of said second housing and aligned with the axis of said first housing and having a pivot bearing pin extending from its upper surface and cooperative with said pivot bearing receptacle to define an upper pivot bearing; and wherein said lower pivot bearing includes; a second post mounted in the bottom plate of said first housing and aligned with said axis of said first housing and having a second pivot bearing pin extending from its upper surface; and a second pivot bearing element mounted in the bottom plate of said second housing and aligned with said axis of said first housing and having a downwardly facing pivot bearing receptacle cooperative with said second pivot bearing pin to define a lower pivot bearing.