Successively electromagnetically scanned x-y grid conductors with a

Abstract

A position digitizing device in which a cursor, moveable within a field generated by successively activated grid wires, developes a voltage from the field and, in conjunction with conditioning circuits, yields the electrical intelligence required to indicate its position with a high degree of precision. Currents are successively passed through parallel grid lines at discretely separate distances, the resultant successively positioned fields successively inducing voltages at the cursor coil output dependent upon the position of the cursor in relation to the actuated grid line. Conditioning equipment to which the cursor output is coupled mixes the cursor output with a reference and introduces circuitry responsive to the rate at which the grid currents are successively stepped to translate the cursor output to a time variant wave form. A reference point developed from that wave form is then used to permit a precision clock to relate the distance of the cursor from a grid line to the time needed to reach the reference point. Cursor position then becomes a function of precisely generated pulses accumulated in a counter.