Patent ID: 7121155

Claim:
A pressure indicating structure comprising: a translucent or transparent sheet having opposite first and second major surfaces, reflective structure defining at least a portion of said second surface for reflecting back through said first surface at an observation angle in a predetermined range of observation angles with respect to said first surface a visually significant amount of the light entering said sheet through said first surface, said reflective structure comprising a multiplicity of peak portions and recessed portions having recessed surface portions of said second surface defining recesses from said peak portions; and a deformable layer comprising pressure sensitive adhesive, said deformable layer having opposite major surfaces with one of said surfaces being defined by said pressure sensitive adhesive and being supported along said second surface of said sheet adjacent said peak portions of said reflective structure and spaced from said recessed surface portions of said second surface; the shape and size of the peak portions and recessed portions of the reflective structure and the deformability of the deformable layer are adapted so that a predetermined pressure is needed between the surface of the deformable layer opposite the reflective structure and the first surface of the sheet to deform the pressure sensitive adhesive defining the first surface of the deformable layer into the recesses to wet part or all of the recessed surface portions of the reflective structure, and said wetting of part or all of the recessed surface portions of said reflective structure causes light to pass through said second surface along the wetted recessed surface portions instead of being reflected, thereby causing significant visually observable changes in the reflectivity of said reflective structure at an observation angle in said predetermined range of observation angles to indicate that said predetermined pressure has been applied.