Position indicator
First Claim
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1. Apparatus for generating a signal representative of a co-ordinate of a movable indicating member, the member being constructed to interact with magnetic flux, and the apparatus including:
- a plurality of sensing coils, positioned substantially in or adjacent to a real or imaginary surface in or adjacent to which the indicating member may be moved, the sensing coils overlapping in the direction of a required co-ordinate in the surface, and being positioned to divide an area of interest in the surface into regions, each coil encircling part of said area of interest having conductors in the said area substantially along region boundaries only, and each region being within an arrangement of the sensing coils particular to that region, a further coil, positioned substantially in or adjacent to the said surface and surrounding the entire area of interest, andmeans responsive to change in magnetic flux passing through the said area of interest by way of the indicating member for providing signals representative of the co-ordinate of the indicating member, by separately combining signals from said further coil with signals from each of said sensing coils to provide a group of binary signals indicative of said coordinate
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Abstract
A graphical input device for computer aided displays is described in which the area of interest is divided by the conductors of two orthogonal sets of coils. Each region of the of interest area is within a coil or combination of coils in each set unique to that region, so that when a change of the magnetic flux associated with a stylus indicating a point of interest occurs, currents induced in the coils represent the position of the point.
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Citations
21 Claims
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1. Apparatus for generating a signal representative of a co-ordinate of a movable indicating member, the member being constructed to interact with magnetic flux, and the apparatus including:
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a plurality of sensing coils, positioned substantially in or adjacent to a real or imaginary surface in or adjacent to which the indicating member may be moved, the sensing coils overlapping in the direction of a required co-ordinate in the surface, and being positioned to divide an area of interest in the surface into regions, each coil encircling part of said area of interest having conductors in the said area substantially along region boundaries only, and each region being within an arrangement of the sensing coils particular to that region, a further coil, positioned substantially in or adjacent to the said surface and surrounding the entire area of interest, and means responsive to change in magnetic flux passing through the said area of interest by way of the indicating member for providing signals representative of the co-ordinate of the indicating member, by separately combining signals from said further coil with signals from each of said sensing coils to provide a group of binary signals indicative of said coordinate - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. Apparatus for generating a signal representative of the position of a point on a surface including:
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a plurality of sensing coils in or immediately below a real or imaginary surface, the sensing coils being arranged to divide an area of interest in the surface into regions, each coil having conductors in the said area along region boundaries only, and each region being within an arrangement of sensing coils particular to that region, a further coil positioned in or immediately below the said surface and surrounding all the said regions, an indicating member movable over the surface for indicating a point, the position of which is required, the member being constructed to guide magnetic flux therethrough, means for changing the magnetic flux linking the sensing coils and the further coil by way of the indicating member, and means responsive to the said change in flux for providing a signal representative of the position of the indicating member, including means for interpreting signals induced in each sensing coil with the assistance of signals induced in the further coil when a change of flux occurs, in providing the signals representative of a coordinate.
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Specification