Switch actuator

Abstract

An automatic switch actuator is disclosed which may be used to test press-to-actuate type switches--for example, the key actuated switches of a computer keyboard. In the illustrated embodiment of the invention, a system of electrically operated valves are used to apply four different fluid pressures to selected pistons of an array of pneumatic cylinders. Each cylinder is mechanically connected to a plunger which is oriented so as to contact a selected key in an array of keys (i.e., a keyboard). The four fluid pressures applied are: (1) sub-ambient ('vacuum') which is used to retract the plungers thereby permitting easy loading and unloading of units under test; (2) 'atmospheric' which is used to rest the plungers directly on the keycaps thereby minimizing dynamic loading of keys during the test; (3) 'low pressure' which is selected to lower the plungers onto the keycaps and subsequently to apply a predetermined force which should not cause switch actuation; and, (4) 'high pressure' which is selected to provide the minimum acceptable force on the plunger required to cause key actuation. The key switches are monitored for actuation by a computer which computer may also be conveniently used to control the pneumatic cylinders.