Membrane switches are switches which are covered with a protective membrane which keeps out harmful contaminants. One contact of the switch is generally attached to the membrane and separated from the lower contact by a dome, which allows the switch to "pop back" after being pressed. Membrane switches are used in low-voltage, momentary closure applications.
Because membrane swiches are sealed, they look and work in a manner that is unique to their design. For example, they can be designed so that they have custom graphics printed on them. Their "feel" or tactile behaviour, depends on their construction. There are several options when purchasing switches, including the use of metal domes, formed tactile domes and formed graphic tactile domes.
Another option when specifying or purchasing your membrane keypads is backlighting. If used in low-light environments, backlighting can improve switch usability. Backlighting can be provided using fiber optics (for low noise applications) or electroluminescent (EL) methods.
In additional to the traditional switches, custom sensors may also be embedded within the membrane. For example, a continuously variable membrane potentiometer may be used. Also possible is the use of an X-Y sensor, which works like a laptop computer's touchpad, and may be used to detect the position of the operator's finger on the membrane for control purposes.