Coded Overlay Sensing Mechanism
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-05
Various keyboards exist of membrane, mechanical or capacitive, electronic or magnetic technology in which changeable indicia overlay sheets are employed with coded elements on their edge to identify to a using system which overlay is in place to modify the interpretation given to the key strokes when they are decoded. In fast food and other similar industries, a contamination shield or permanent membrane must be in place over the key elements to avoid fouling due to spilled foodstuffs and the like. This disclosure provides a coded overlay indicia sheet with encoding tabs on its edge that actuate mechanical switches beneath the permanent contamination shield on such a keyboard to indicate to a using system which overlay is in place.