High-frequency electrosurgical unit with timed safety shut down interlock

High-frequency electrosurgical unit for cutting and coagulating biological tissues, including at least one high-frequency generator capable of being individually put into and taken out of operation by control of an enabling circuit thereof including a main power on-off switch, said at least one high-frequency generator having a high-frequency transformer, said unit also comprising:

• a rectifier circuit individual to said high-frequency transformer of said at least one high-frequency generator for providing a first electrical output signal (u.sub.1) when and so long as said at least one high-frequency generator is in an activated state;
• a first delay circuit (13), to which said first output signal (u.sub.1) is provided as an input, for producing a second output signal (u.sub.2) when said first output signal (u.sub.1) has persisted without interruption for more than a first time interval (t.sub.13), said first delay circuit having means for adjusting the duration of said first time interval;
• means (14) connected to said first delay circuit (13) for producing an audible signal for so long as said second output signal (u.sub.2) of said first delay circuit (13) persists;
• a second delay circuit (15) having said second output signal (u.sub.2) of said first delay circuit (13) as an input, for producing a third output signal (u.sub.3) when said second output signal (u.sub.2) has persisted without interruption for more than a second time interval (t.sub.15), said second delay circuit (15) having means for adjusting the duration of said second time interval;
• cut-off relay means (16,17) having a switching path interposed in said enabling circuit and connected to allow completion of said enabling circuit when said at least one one high-frequency generator is put into operation and to interrupt said enabling circuit immediately at the end of said second time interval (t.sub.15) in response to said third output signal (u.sub.3) of said second delay circuit (15), and
• means for restoring enablement of said at least one high-frequency generator and restarting said second delay circuit (15) after interruption of said enabling circuit by said cut-off relay means in response to turning off said main power switch and quickly thereafter turning said main power switch back on.