Coordinate sensing device
First Claim
Patent Images
1. A coordinate sensing device comprising:
- a fine meshed fabric screen having electrical conductive properties and defining a major surface;
first current source means for selectively establishing a first electrical current between a first injection point and first sink point on said major surface, said first injection and sink points defining a first electrical field across the said major surface;
second current source means for selectively establishing a second electrical current between a second injectionand a second sink point on said major surface, said second injection point and sink points defining a second electric field across the said major surface, the two electric fields related so that the position of the equipotential lines from each field intersect at unique points;
probe means for selectively sensing a first electrical potential on the first electric field at a physical point on the surface between the first injection and sink points and a second electrical potential on the second electric field at the same physical point on the surface between the second injection and sink points;
means for converting said sensed first or second potentials to an intelligent signal representing the coordinates of the physical point indicated in any chosen coordinate system.
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Abstract
A coordinate sensing device uses electric currents to energize a conducting member which has a major surface and preferably is made of mesh material. Electrical currents are sequentially applied to create alternate noncoincident electrical fields so that when a probe is applied to the surface, the obtained electrical potentials can be compared to a reference potential. The resulting potential differences may then be conveniently converted to appropriate signals. The conducting member is not limited as to shape or construction; hence, it may also act as an anti-glare device for a cathode-ray tube. The fields created by the electrical currents need not be uniform.
58 Citations
22 Claims
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1. A coordinate sensing device comprising:
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a fine meshed fabric screen having electrical conductive properties and defining a major surface; first current source means for selectively establishing a first electrical current between a first injection point and first sink point on said major surface, said first injection and sink points defining a first electrical field across the said major surface; second current source means for selectively establishing a second electrical current between a second injectionand a second sink point on said major surface, said second injection point and sink points defining a second electric field across the said major surface, the two electric fields related so that the position of the equipotential lines from each field intersect at unique points; probe means for selectively sensing a first electrical potential on the first electric field at a physical point on the surface between the first injection and sink points and a second electrical potential on the second electric field at the same physical point on the surface between the second injection and sink points; means for converting said sensed first or second potentials to an intelligent signal representing the coordinates of the physical point indicated in any chosen coordinate system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A coordinate sensing device comprising:
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an electrical conducting member formed of fine mesh material defining a major surface; first current source means for selectively establishing a first electrical current between at least one injection point and at least one sink point on said major surface, said injection and sink points defining a first electrical field across the said major surface; second current source means for selectively establishing a second electrical current between at least one second injection point and at least one second sink point on said major surface, said second injection and sink points defining a second electric field across the said major surface, the two electrical fields related so that the position of the equipotential lines from each field intersect at unique points; probe means for selectively sensing a first electrical potential on the first electrical field at a physical point on the surface and a second electrical potential on the second field at the same physical point; means for converting said sensed first or second potentials to an intelligent signal representing the coordinates of the physical point indicated in any chosen coordinate system. - View Dependent Claims (16)
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17. A coordinate sensing device in combination with a video display device comprising:
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a fine meshed fabric screen having electrical conductive properties and defining a major surface, said fine meshed fabric screen fixable to the picture-generating surface of the video display device; first current source means for selectivity establishing a first electrical current between a first injection point and a first sink point on said major surface, said first injection and sink points defining a first electrical field across said major surface; second current source means for selectivity establishing a second electrical current between a second injection point and a second sink point on said major surface, said second injection and sink points defining a second electrical field, the two electric fields related so that the position of the equipotential lines from each field intersect at unique points; switching means for alternately energizing said first and second current source means; probe means for selectively sensing a first electrical potential on the first electrical field at a physical point on the major surface and a second electrical potential on the second electrical field at the same physical point; means for converting said sensed first or second potential to an intelligent signal; computer means for imposing the intelligent signal on the surface of the video display device at the point selected by the probe means. - View Dependent Claims (18, 19, 20, 21)
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22. A relatively flexibe electrical conducting member for a curved video display screen comprising:
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a thin portable frame of a flexible material; a microweave mesh of black filaments stretched across the inner surface of said frame, said frame having electrical conductive properties, at least some of said black filaments capable of conducting electrical current, and affixed to said frame; said frame sufficiently wide enough that it resists bending in all directions in the plane of the mesh but being flexible in all directions transverse thereto so that said frame and stretched mesh will conform to the curvature of a video display device to which the frame is attached; means for attaching said frame to a terminal display scope so that said mesh conforms to contact said scope over the surface thereof.
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Specification