Chair mat

Claim 1

A chair mat for reducing the generation of static electricity from castered furniture rolling across the mat, and/or an individual walking across the mat and for dissipating the static electricity from a charged individual stepping onto the mat, the mat having an external edge and comprising: (1) a substantially transparent top layer having an outer surface and an inner surface and a bulk resistivity of less than 10 11 ohm-cm, (2) a transparent conductive layer comprising an interconnected grid work pattern and having first and second outer surface areas, the second surface secured to the inner surface of the top layer, the conductive layer having a resistivity ranging from 1/2 to 10 9 ohm-cm, the grid work pattern having lines with widths of at least 0.005 inches and a repetitive geometric conductive grid work pattern providing a small fraction of the surface area of the layer compared to the total surface area of the mat. (3) a transparent base layer having an outer surface and an inner surface, the inner surface secured to the first surface of the conductive layer, all layers forming a sandwich laminate structure such that the outer surface of the top layer of the mat has a surface resistivity of less than 2×10 10 ohms, the mat is at least 50% transparent so that the color of an underlying carpet can be easily seen through the whole mat and substantially preventing the generation of static electricity when castered furniture rolls a cross the outer surface; and (4) ground means connected to the outer surface of the top layer and the outer surface of the transparent base layer and isolated electrically from the gridwork pattern.