US 4,451,698 A · Coordinate digitizing device

Abstract

Coordinate digitizers comprise a data tablet having perpendicular X and Y axes grids, which cross each other to define a data surface. Each grid has a plurality of parallel evenly-spaced-apart grid wires having their ends connected by end busses. An inductor connected to an alternating electrical input signal is movable on the data surface, and induces current flow in loops comprised of individual grid wires and end busses, with the strength of the current strongest in the grid wires near the inductor. Each grid has a receptor loop into which signals from the grid are induced, and the receptor loop is preferably deployed in a receptor area off the data surface. The receptor loops are configured such that signals induced therein correlate to inductor position on the data surface. The receptor loops are preferably composite loops providing complimentary signals to compensate for variations in the input signal or an induction-to-grid coupling. The data tablet may be translucent and backlighted to form a light-box digitizer. A microprocessor calculates inductor position from the receptor loop signals. A self-contained cursor comprising an inductor coil, signal generator means and a battery power supply in a housing for use on the data tablet eliminates input leads.

Claims37

Dependent claims

A coordinate digitizer comprising:

(A) a first grid including a first plurality of conductive grid wires deployed spaced-apart on a data surface and end busses connecting the respective ends of the first grid wires;
(B) an inductor adapted for movement to positions of interest on said data surface and for inducing electrical signals into said first grid;
and
(C) a first conductive receptor loop deployed proximate said first grid and configured to have induced therein from said first grid electrical signals which vary according to the position of the inductor on the data surface;
wherein, upon application of an alternating electrical input signal to said inductor, the inductor induces alternating electrical signals into said first grid, said electrical signals being distributed in the first grid wires according to the position of the inductor on the data surface, and the alternating electrical signals in the first grid induce an electrical output signal in the first receptor loop which varies according to the position of the inductor on the data surface, whereby the position of the inductor can be determined from the output signal in the first receptor loop.

2 more elements

An improved data tablet for use in a coordinate digitizing system of the type generally comprising an inductor connected to an alternating input signal source, a data tablet on which the inductor is movable, and calculating means for receiving the output of the data tablet and determining the position of the inductor thereon, the improved data tablet comprising:

(A) an X-axis grid including a first plurality of conductive grid wires deployed parallel, spaced-apart and coplanar, and end busses connecting the respective ends of the grid wires;
(B) Y-axis grid including a second plurality of conductive grid wires deployed parallel, spaced-apart, coplanar with respect to each other, and perpendicular to the grid wires of the X-axis grid, and end busses connecting the respective ends of the Y-axis grid wires, the crossing grid wire areas of said X-axis and Y-axis grids defining the data surface of the data tablet;
(C) means supporting said X-axis and Y-axis grids and forming a smooth surface overlying the crossing areas of said X-axis and Y-axis grids, for receiving drawings and the like and for receiving the inductor;
(D) each of said X-axis and Y-axis grids further comprising a receptor area comprising a portion of the grid wires and one end bus extending from the data surface;
and
(E) an X-axis receptor loop and a Y-axis receptor loop respectively deployed in the receptor areas of the X-axis and Y-axis grids, each receptor loop configured to have induced therein from its respective grid electrical signals which vary according to the position of the inductor on the data surface of the data tablet, said electrical signals in said receptor loops comprising the output of the data tablet.

3 more elements

Dependencies are inferred from the claim text.

Coordinate digitizing device

Life of this patent

Coordinate digitizing device

Life of this patent

Abstract

Claims37