TOUCH SENSITIVE SWITCHES

摘要

A touch sensitive switch comprises a liquid crystal cell and means for measuring capacitive changes when the cell is deformed by touch. The cell comprises a layer of a liquid crystal material between slides bearing electrodes, Capacitive changes are detected for example by a comparator or by a bridge circuit which includes one or more cells. Touching one cell unbalances the bridge. The area of cell that is touched may be coincident with or separate from a display area. For some types of cell extra sensitivity is achieved by maintaining a voltage across the cell between a critical and saturation value.