Lexmark International, Inc.

Philip Michael Cullen

Louann Behymer Samuels

Dell T Rosa

Edwin T Coleman, Iii

Mary L VanArsdall

The present invention relates to chromogenic material that may respond and shift in color due to environmental conditions such as heat, light or humidity. The light may include both visible and non-visible light, such as ultraviolet light. The chromogenic material may therefore provide a method to independently develop a latent image on a given substrate, and in particular, to a substrate that includes conventional thermosensitive image forming media.

Chromogenic media responsive to environmental conditions

First and second membranes carrying contacts located on opposing faces are separated by a third or spacer membrane having holes therein so that a circuit may be completed between the contacts when a force is applied to the first membrane. The first and second membranes and the peripheries of the holes define substantially enclosed switch regions. The first, second and third membrane layers are mechanically held together, without the use of adhesives, in the regions other than the switch regions. Spacer elements are provided between the spacer membrane and one of the first and second membranes. The spacer elements form air pockets such that air may flow between the switch region and the air pockets as the first membrane is depressed and then released. The arrangement provides two advantages. First, it reduces pressure buildup, such as would occur if the membranes were sealed together, when force is applied to the first layer. Secondly, it reduces pressure variations in the switch region where a vacuum would otherwise be created as the first membrane returns to its undepressed position. The contacts thus open more quickly thereby reducing the possibility of contact bounce. The spacer elements might be either conductive or dielectric. If they are conductive they may be applied during the same screening pass that places conductors and contacts on the first or second layer. If they are non-conductive they may be applied during the same screening pass that places a dielectric on the flextail portion of a membrane.

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Lexington, KY, United States of America

Philip Michael Cullen