Control-safe capacitive switch

摘要

A palm-button control system provides for machinery control with minimized operator hand pressure by use of capacitive switches and reduced susceptibility to radio frequency interference. The system employs first and second capacitive palm-button switches, both of which must be contacted before machinery is activated. Each capacitive palm-button includes a radio frequency sensor which functions to disable machine activation in the presence of a sufficiently strong radio signal. Circuitry for periodically testing the radio frequency sensors provides periodic visual operator feedback indicative of operability of the system. All controls are synchronized or enabled in accordance with a series of digital pulses.