| 摘要 |
A monitoring circuit (10) for monitoring the state of the capacitive proximity switches (14, 42) used in a two hand industrial machine control station (13) is disclosed. Each proximity switch (14, 42) has a monitoring circuit (18, 46) for monitoring the length of time that the proximity switch remains activated. The monitoring circuits (18, 46) are connected together via relays (26, 54) such that both switches must be activated within a set time window in order to activate the machine control circuit (13). The circuit also reduces the chance of unintended operation of the machine (13) as a result of emitted or conducted radio frequency interference by the use of a grounded metallic enclosure (135) and switches (14, 42) that have different radio frequency sensitivity characteristics. |
