Electronic coordinate position digitizing system

Apparatus for measuring the position of a cursor relative to a set of coordinate axes on a reference surface comprising an X-axis polyphase grid winding with each phase winding disposed in a plane parallel to said surface and having conductors spaced in the direction of the X-axis, a Y-axis polyphase grid winding with each phase winding disposed in a plane parallel to said surface and having conductors spaced in the direction of said Y-axis, X-axis switching means connected with said X-axis grid winding, Y-axis switching means connected with said Y-axis grid winding, a clock pulse generator, control means connected with said generator and having a first output and a second output connected respectively with said X-axis switching means and said Y-axis switching means, and producing X-axis and Y-axis enable pulses alternately on said first and second outputs, said cursor including a sensing coil inductively coupled with the X-axis and the Y-axis polyphase grid windings, said enable pulses alternately enabling said X-axis switching means and said Y-axis switching means whereby said X-axis and Y-axis grid windings are alternately excited and whereby said cursor alternately produces an X-axis position signal and a Y-axis position signal, and phase angle measuring means connected with the cursor for measuring the respective phase angles of the position signals.

Apparatus for measuring the position of a cursor along a coordinate axis on a reference surface comprising, a measurement grid including multiple parallel conductors spaced in the direction of the coordinate axis, grid excitation means connected with said conductors for sequentially applying current pulses thereto, a counter connected with said excitation means for counting the pulses, means for clearing the counter before the application of a pulse to the first conductor, said cursor including a sensing means coupled with the conductors for producing a cursor signal, stop pulse means connected with the sensing means for producing a stop pulse in response to a cursor signal caused by the excitation pulse applied to the conductor nearest the position of the cursor, said stop pulse means being connected with said counter to stop the counter at a count indicative of the position of the cursor.

An apparatus for measuring the position of a cursor along a coordinate axis on a reference surface, said apparatus being of the type comprising a polyphase grid winding disposed in a plane parallel to said surface with each phase winding having multiple parallel conductors spaced in the direction of said axis and forming multiple pairs of poles in said grid winding, said cursor including a winding in coupled relation to said grid winding, excitation means connected with one of said windings, and phase angle measuring means connected with the others of said windings, the improvement comprising plural conductors per pole in each phase winding, the conductors of each pole being spaced apart within the pole length to produce an approximately sinusoidal distribution of magnetic flux.