Angular displacement measuring apparatus

Apparatus for providing dual pivotal balance support comprising:

• a hub having a central chamber having generally cylindrical sidewalls extending thereinto from one external surface of said hub with said chamber terminating in a conical surface,
• a generally cylindrical shaped column having a point at one end thereof cooperating with said conical surface for providing a needle bearing support for said hub when the axis of said column is oriented substantially vertically, said chamber sidewall including a raised shoulder portion having an inner surface in spaced circumferentially surrounding relation to said column, and
• means retaining at least the portion of said column including said point within said chamber while permitting sufficient axial movement of said column with respect to said hub for disengaging said column point from said conical surface, said retaining means including a first O-ring attached to said chamber sidewall in spaced relation to said shoulder and a second O-ring attached to said column, said first and second O-rings cooperating for preventing said column point from escaping from within said chamber while permitting sufficient axial movement of said column for disengaging said column point from said conical surface so that said column is rotatably supported relative to the circumference thereof by said inner surface of said chamber sidewall shoulder and the inner circumferential surface of said O-ring.

Apparatus for selectably indicating angular relation with respect to an external magnetic field or with respect to a horizontal reference comprising:

• a substantially cylindrical column having a point at one end,
• a pivotal assembly including a hub having a bistable balance, a disc, and a magnetic field source all rigidly attached to said hub as a unit, said hub having an inwardly extending cylindrical chamber terminating in a conical depression for balancing said assembly on said column point when the axis of said column is oriented substantially vertically and for retainably supporting the circumference of said column by the sidewalls of said chamber when the axis of said column is oriented substantially horizontally, said bistable balance having a mass movable between first and second positions with said first position providing a balanced relation relative to said column axis when said axis is oriented substantially vertically and with said second position providing an offset weight relative to said column axis when said axis is oriented substantially horizontally thereby defining a vertical reference for said assembly, said disc having a plurality of circular tracks each arrayed as a series of binary indicia containing cells with the said indicia for each radial sequence of said cells representing the angular orientation of said disc,
• means radially arrayed relative to the axis of said disc and mounted in a fixed position relative to said column for sensing said indicia from said tracks for producing multi-bit characters determined by said indicia in accordance with the rotary position of said disc with respect to the axis of said column,
• utilization circuit means responsive to multi-bit characters for providing an electronic output operation, and
• gating circuit means for controlling the transfer of said multi-bit characters from at least some of said sensing means to said utilization circuit means whenever said sensing means are positioned relative to said tracks at locations away from the radial boundaries of said cells, whereby said multi-bit characters represent angular relation to an external magnetic field when said column axis is oriented substantially vertically an angular relation to horizontal when said column axis is oriented substantially horizontally.