Film confined to a frame having relative anisotropic expansion characteristics

DETAILED DESCRIPTION The following terms should be understood in the description of the present invention according to the meanings ascribed below: "x-y plane" refers to any of a set of parallel planes indicating the general orientation of the planar bounded material and planar bounding material of the present invention.
In the case of a display assembly, the x-y plane is a plane perpendicular to the net direction of light output.
The horizontal direction will be understood as the x-direction in the x-y plane and the vertical direction will be understood as the y-direction in the x-y plane.
"z-direction" refers to the direction perpendicular to the x-y plane and generally corresponds to the thickness direction of the planar bounded material of the present invention.
"frame" refers to an object having internal bounding edges enclosing a substantially planar area in the x-y plane.
"anisotropic film" refers to a substantially planar film or sheet of material having anisotropic expansion characteristics in the plane of the film or sheet.
"clearance" refers to an area located between the film and the internal bounding edges of the frame.
"play" refers to the amount of film movement in the frame allowed by clearance.
"slippage" refers to movement of the film resulting in edges of the film lying outside of a desired region in the frame.
"warping" refers to buckling of the film in the thickness direction due to compressive stresses in the plane of the film resulting from contact between the film edges and the internal bounding edges of the frame.
"free floating" and "loosely secured" refer to the mounting of a film in a frame such that the film has at least some freedom of motion in at least one direction.
"planar" is used to refers to an object having dimensions in two orthogonal directions substantially greater than its dimension in a third orthogonal direction, the third orthogonal direction usually called the thickness.
"reference temperature" refers to a temperature condition selected for its significance in a given application