Graphic communication apparatus

DETAILED DESCRIPTION What is claimed is: 1.
Graphic communication apparatus, comprising, in combination: a writing surface; pen means movable on the writing surface for graphically portraying information on the writing surface; input signal means for providing an input signal to the pen means; pen coil means, including a plurality of pen coils, disposed in the pen means for producing a magnetic field in response to the input signal as the pen moves on the writing surface; sense coil means for sensing the magnetic field produced by the pen coil means and for producing output signals in response thereto, including X direction sense coil means for sensing the magnetic field produced by the pen coil means in an X direction, and Y direction sense coil means for sensing the magnetic field produced by the pen coil means in a Y direction; and circuitry means connected to the sense coil means for receiving the output signal from the sense coil means and for producing an output signal representative of the location of the pen means on the writing surface.
2.
The apparatus of claim 1 in which the X direction sense coil means comprises a first X direction coil, and a second X direction coil spaced apart from and aligned generally parallel to the first X direction coil.
3.
The apparatus of claim 1 in which the X direction sense coil means includes a plurality of X direction coils spaced apart from and disposed substantially parallel to each other.
4.
The apparatus of claim 3 in which each coil of the plurality of X direction coils includes the same number of turns.
5.
The apparatus of claim 4 in which each coil of the plurality of X direction coils of the X direction sense coil means includes a first conductor for providing a first output signal and a second conductor for providing a second output signal.
6.
The apparatus of claim 5 in which the plurality of X direction coils of the X direction sense coil means includes a first plurality of resistors connected to the first conductor and a second plurality of resistors connected to the second conductor, and each resistor of the first and second pluralities of resistors is selected to provide a different output signal on the first and second conductors from each coil of the plurality of X direction coils in response to the location of the pen means relative to any one coil of the plurality of X direction coils