Capacitive two dimensional tablet with single conductive layer
First Claim
1. A capacitive tablet having a single layer of electrodes in the active area of the tablet, comprising,a generally planar insulating member having a unitary surface forming a support,a plurality of electrode pairs formed on said support, each pair being shaped to establish a relatively thin line of equi-potential when the two electrodes of a pair are electrically energized at the same alternating voltage, said pairs being closely spaced to establish a parallel array of said lines on said support,each element of a pair being spaced apart to be differently energized and being complementarily shaped to establish a voltage gradient along each said line at the operating height of a pen above the tablet when the electrodes of a pair are differently energized, andmeans for energizing the electrodes for pen position determining operations.
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Abstract
A new capacitive tablet has a single layer in which electrodes provide capacitive coupling with a pen to produce signals that correspond to the X and Y dimensions of the position of the pen on the tablet. The electrodes in the single layer are in the form of pairs of complementary shaped, closely adjacent, conductive elements that extend in the Y dimension of the tablet. For sensing the pen position in the Y dimension, an alternating voltage is applied between the two elements of a pair and the pen receives a signal that is a function of the pen position in the Y dimension. The tablet includes a number of such pairs, each having a different X dimension position, and for sensing the pen position in the X dimension, the two electrodes of a pair are given an alternating voltage that differs progressively across the X dimension of the tablet.
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Citations
8 Claims
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1. A capacitive tablet having a single layer of electrodes in the active area of the tablet, comprising,
a generally planar insulating member having a unitary surface forming a support, a plurality of electrode pairs formed on said support, each pair being shaped to establish a relatively thin line of equi-potential when the two electrodes of a pair are electrically energized at the same alternating voltage, said pairs being closely spaced to establish a parallel array of said lines on said support, each element of a pair being spaced apart to be differently energized and being complementarily shaped to establish a voltage gradient along each said line at the operating height of a pen above the tablet when the electrodes of a pair are differently energized, and means for energizing the electrodes for pen position determining operations.
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8. A capacitive tablet comprising,
a generally flat support providing an active area that is generally rectangular and having sides arbitrarily designated top, bottom, right and left, means operable for a Y dimension pen position sensing operation providing an oscillatory voltage of a predetermined amplitude across the top of the tablet and a non-oscillatory potential across the bottom of the tablet, whereby a ramp voltage gradient exists across the tablet, rising from bottom to top, conductors formed in an array on said support in a common plane and conductively isolated from each other and from said oscillatory voltage means and said ground potential means for establishing the capacitive coupling of a pen to sense said ramp voltage, and means operable for a separate X dimension pen position sensing operation for establishing a voltage gradient rising from left to right across the tablet.
Specification