Electrographic apparatus

Claim 2

Electrographic apparatus comprising: an electrically insulative support; a layer provided as an indium-tin-oxide grain deposition located upon said support having a thickness greater than about 400 angstrum units predetermined to avoid resistivity drift phenomena occasioned by environmental interaction with the outwardly exposed grains of said layer and having a given surface resistivity corresponding with said predetermined thickness; said layer defining an active area located within a given profile having a widthwise extent in an x-coordinate direction between first and second spaced apart edges which exhibits a first edge-to-edge resistance therebetween and a lengthwise extent in a y-coordinate direction between third and fourth spaced apart edges which exhibits a second edge-to-edge resistance therebetween; said layer within said active area having a pattern of discrete discontinuities; wherein said pattern of discontinuities is configured to provide an edge-to-edge resistance aspect ratio between 0.5 and 2.0; said first and said second edge-to-edge resistances being within a range of about 400 to 3,000 ohms; and access means for capacitively accessing said layer to derive position related signals.

Claim 3

The electrographic apparatus of claim 1 in which: each of said discrete discontinuities includes a width dimension which extends in the x-coordinate direction; each of said discrete discontinuities includes a height dimension which extends in the y-coordinate direction; adjacent ones of said discontinuities defining a first set of parallel tracks in which each track has the same widthwise dimension, T1, extending between said discontinuities in said x-coordinate direction; adjacent ones of said discontinuities defining a second set of parallel tracks in which each track has the same widthwise dimension T2 extending between said discontinuities in said y-coordinate direction; said first edge-to-edge resistance divided by said given surface resistivity has a value N1; said second edge-to-edge resistance divided by said given surface resistivity has a value N2; said width dimension being N1-1 times greater than the widthwise dimension T1 of a said track of said first set of tracks; and said height dimension being N2-1 times greater than the widthwise dimension T2 of a said track of said second set of tracks.

Claim 4

The electrographic apparatus of claim 2 in which: said widthwise dimension T1 of each one of said first set of tracks is equal to said widthwise dimension T2 of each one of said second set of tracks.

Claim 5

The electrographic apparatus of claim 2 in which: said active area is square; and said width dimension of said discontinuities is equal to said height dimension.

Claim 6

The electrographic apparatus of claim 2 in which: said active area is rectangular and non-square; and said width dimension of said discontinuities is unequal to said height dimension.

Claim 7

The electrographic apparatus of claim 1 in which: said layer extends from said given profile to an outer profile located outwardly of said given profile to define an enhanced conductivity band therebetween exhibiting a surface resistivity corresponding with said given surface resistivity; and said access means includes electrode means coupled in electrical association with said enhanced conductivity band.

Claim 8

The electrographic apparatus of claim 6 in which a second pattern of discontinuities is provided in said enhanced conductivity bands.

Claim 9

The electrographic system of claim 1 in which said given surface resistivity is less than about 400 ohms per square.

Claim 10

The electrographic system of claim 1 in which said edge-to-edge resistance aspect ratio is unity.

Claim 11

An electrographic system comprising: an electrically insulative support; a layer provided as an indium-tin-oxide grain deposition located upon said support having a thickness greater than about 400 angstrum units predetermined to avoid resistivity drift phenomena occasioned by environmental interaction with the outwardly exposed grains of said layer and having a given surface resistivity corresponding with said predetermined thickness; said layer defining an active area located within a given profile having a widthwise extent in an x-coordinate direction between first and second spaced-apart edges which exhibits a first edge-to-edge resistance therebetween and a lengthwise extent in a y-coordinate direction between third and fourth spaced-apart edges which exhibits a second edge-to-edge resistance therebetween; said layer within said active area having a pattern of discrete discontinuities; each of said discrete discontinuities includes a width dimension which extends in the x-coordinate direction; each of said discrete discontinuities includes a height dimension which extends in the y-coordinate direction; adjacent ones of said discontinuities defining a first set of parallel tracks in which each track has the same widthwise dimension, T1, extending between said discontinuities in said x-coordinate direction; adjacent ones of said discontinuities defining a second set of parallel tracks in which each track has the same widthwise dimension T2 extending between said discontinuities in said y-coordinate direction; said first edge-to-edge resistance divided by said given surface resistivity having the value N1; said second edge-to-edge resistance divided by said given surface resistivity having the value N2; said width dimension being N1-1 times greater than the widthwise dimension T1 of a said track of said first set of tracks; said height component being N2-1 times greater than the widthwise dimension T2 of a said track of said second set of tracks; said discontinuities being configured to provide an edge-to-edge resistance aspect ratio of unity; said first and said second edge-to-edge resistances being within a range of about 400 to 3,000 ohms; said layer extends from said given profile to an outer profile to define an enhanced conductivity band therebetween exhibiting a surface resistivity corresponding with said given surface resistivity; access means including electrode means coupled in electrical association with said enhanced conductivity band; locator means locatable adjacent said active area; a time varying a.c. excitation source having a frequency of less than about 250 KHz; a ground reference; control means for collecting a signal from said locator means; and means for selectively electrically communicating said excitation source and said ground reference with said electrode means.

Claim 12

An electrographic system comprising: an electrically insulative support; a layer provided as an indium-tin-oxide grain deposition located upon said support having a thickness greater than about 400 angstrum units predetermined to avoid resistivity drift phenomena occasioned by environmental interaction with the outwardly exposed grains of said layer and having a given surface resistivity corresponding with said predetermined thickness; said layer defining an active area located within a given profile having a widthwise extent in an x-coordinate direction between first and second spaced-apart edges which exhibits a first edge-to-edge resistance therebetween and a lengthwise extent in a y-coordinate direction between third and fourth spaced-apart edges which exhibits a second edge-to-edge resistance therebetween; said layer within said active area having a pattern of discrete discontinuities; each of said discrete discontinuities includes a width dimension which extends in the x-coordinate direction; each of said discrete discontinuities includes a height dimension which extends in the y-coordinate direction; adjacent ones of said discontinuities defining a first set of parallel tracks in which each track has the same widthwise dimension, T1, extending between said discontinuities in said x-coordinate direction; adjacent ones of said discontinuities defining a second set of parallel tracks in which each track has the same widthwise dimension T2 extending between said discontinuities in said y-coordinate direction; said first edge-to-edge resistance divided by said given surface resistivity having the value N1; said second edge-to-edge resistance divided by said given surface resistivity having the value N2; said width dimension being N1-1 times greater than the widthwise dimension T1 of a said track of said first set of tracks; said height component being N2-1 times greater than the widthwise dimension T2 of a said track of said second set of tracks; said discontinuities being configured to provide an edge-to-edge resistance aspect ratio of unity; said first and said second edge-to-edge resistances being within a range of about 400 to 3,000 ohms; said layer extends from said given profile to an outer profile to define an enhanced conductivity band therebetween exhibiting a surface resistivity corresponding with said given surface resistivity; access means including electrode means coupled in electrical association with said enhanced conductivity band; locator means locatable adjacent said active area; a time varying a.c. excitation source having a frequency of less than about 250 KHz; a ground reference; control means for collecting a signal from said locator means; and means for selectively electrically communicating said excitation source and said ground reference with said electrode means.