Touch screen having reduced visibility transparent conductor pattern

A transparent touch screen construction, comprising:

• a substrate;
• a plurality of layer stacks disposed on the substrate leaving areas of the substrate exposed and areas of the substrate covered by the stacks, each layer stack comprising a transparent conductor layer and an intermediate layer, the intermediate layer having a first major surface in contact with the substrate and a second major surface in contact with the transparent conductor layer, the intermediate layer having an index of refraction that is less than that of the transparent conductor layer and less than that of the substrate, each stack further comprising an overlayer in contact with the transparent conductor layer so that the transparent conductor layer resides between the intermediate layer and the overlayer, the overlayer also being disposed on the substrate in the areas exposed by the stacks, the overlayer having an index of refraction that is less than that of the transparent conductor layer;
• a plurality of lead lines electrically connected to the transparent conductor layers and configured for connecting to controller electronics adapted to determine touch input information based on signals received when a touch input is coupled to the transparent conductors;
• an adhesive layer disposed on the transparent conductor layer disposed on the overlayer of each layer stack in the areas covered by the stacks, the adhesive layer also being disposed on the substrate in the areas exposed by the stacks, the adhesive layer having a different material composition than the intermediate layer;
• wherein a thickness of the transparent conductor layer and a thickness of the intermediate layer are tailored to provide a difference in visible light transmission through the areas covered by the stacks and the areas exposed by the stacks that has a maximum over a range from 400 to 700 nm of about 1% or less and an average over the 400 to 700 nm range of about 0.5% or less.

A method for reducing the visibility of a patterned transparent conductor in a touch screen, comprising:

• providing a substrate covered with a transparent conductor layer and an intermediate layer, the intermediate layer having a first major surface in contact with the substrate and a second major surface in contact with the transparent conductor layer, the intermediate layer having an index of refraction that is less than that of the transparent conductor layer and less than that of the substrate;
• patterning the transparent conductor layer;
• and
• patterning the intermediate layer to coincide with the patterned transparent conductor layer to provide a plurality of layer stacks on the substrate leaving areas of the substrate exposed by the stacks and areas of the substrate covered by the stacks;
• and
• disposing an adhesive material over the plurality of layer stacks such that the adhesive material covers both the areas of the substrate covered by the stacks and the areas of the substrate exposed by the stacks, the adhesive material having an index of refraction that is less than that of the patterned transparent conductor layer, the adhesive material also having a different material composition than the intermediate layer;
• wherein the patterning is carried out and thicknesses of the intermediate layer and the patterned transparent conductor are tailored such that a difference in visible light transmission through the areas covered by the stacks and the areas exposed by the stacks has a maximum over a range from 400 to 700 nm of about 1% or less and an average over the 400 to 700 nm range of about 0.5% or less.

A touch input system, comprising:

• a touch screen overlay comprising a substrate on which is formed a plurality of layer stacks, the plurality of layer stacks being arranged so as to leave areas of the substrate exposed by the stacks and areas of the substrate covered by the stacks, the plurality of layer stacks including a transparent conductor sensing element pattern disposed on the substrate in an active area of the touch screen, and an intermediate layer pattern coincident with the transparent conductor sensing element pattern and having a first major surface in contact with the substrate and a second major surface in contact with the transparent conductor sensing element pattern, the intermediate layer having an index of refraction that is less than that of the transparent conductor and less than that of the substrate, the touch screen overlay also including an adhesive material that covers both the areas of the substrate covered by the stacks and the areas of the substrate exposed by the stacks, the adhesive material having an index of refraction that is less than that of the transparent conductor sensing element pattern, the adhesive material also having a different material composition than the intermediate layer;
• controller electronics coupled to the transparent conductor sensing element pattern and configured to receive signals from the touch screen overlay due to a touch input in the active area and to determine information related to the touch input from the received signals;
• and
• a display device viewable through the touch screen overlay;
• wherein a thickness of the transparent conductor sensing element pattern and a thickness of the intermediate layer pattern are tailored to provide a difference in visible light transmission of the touch screen overlay through the areas covered by the stacks and the areas exposed by the stacks that has a maximum over a range from 400 to 700 nm of about 1% or less and an average over the 400 to 700 nm range of about 0.5% or less.