Importance

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Abstract

An improved touch overlay for the viewing surface of a display for detecting both finger touch and stylus location is disclosed. An upper and a lower set of transparent conductors are disposed on at least one transparent flexible insulating substrate and are oriented orthogonally with respect to each other. Depending on the orientation of the transparent conductors, top and bottom cover layers may be added to the overlay. The separation between the upper and lower conductors and a separation from the user's finger on the top surface of the overlay from the upper conductors is optimized. To speed finger touch sensing, the ambient capacitance of the overlay is reduced by increasing the separation between the upper and lower conductors layers. For improved operation, the present invention features a separation of at least 3 mils between upper and lower conductors. The separation between the top surface and the upper conductors is held to a minimum consistent with the preservation of integrity of the upper conductors when stylus pressure is applied. Means are also included in the overlay to improve the durability of the overlay with respect to repeated stylus pressure on top surface.

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First Claim