Patent ID: 7377062

Claim:
In an illuminated airport guidance sign for the type that includes a pair of curved translucent or transparent legend panels formed of a sheet of a sturdy plastic material the legend panels being bowed out in respect to a generally horizontal axis; a sign frame supporting the legend panels in a symmetric oppositely facing orientation, the frame having edge channels that extend straight along a lower portion of the frame to support a lower edge of an associated legend panel, and side channels that extend along a curve to support curved side edges of the associated legend panel; a base closing off the bottom of the sign; a top cover that closes off a top of the sign; one or more lamps supported within the sign between said pair of legend panels; electrical power means for providing current to said lamps so as to produce even illumination from said lamps; support legs supporting the base of said sign upon a support surface alongside a runway or taxiway, each of said support legs including a frangible coupling designed to break at a predetermined stress; the improvement in which each of said curved legend panels is formed of a sheet of translucent or transparent plastic material that has a thickness on the order of about ⅜ inches between its edges, said thickness being sufficient to resist deflection of said legend panels under forces less than the predetermined design stress of said frangible couplings, and edge portions along each edge of a smaller thickness to fit into said frame edge channels.