Automatic control of electrotherapeutic apparatus

Abstract

Abstract 1,201,586. Electrotherapeutic apparatus. DY NAPOWER SYSTEMS CORP OF CALIFORNIA. 22 Jan., 1969 [15 Feb., 1968], No. 3560/69. Heading A5R. Electrotherapeutic apparatus includes a power radiating head 10 having means for the transmission of high frequency radiation including coupled primary and secondary coils, 12 and 13, and a capacitor 14 connected to the secondary coil to form a tank circuit tuned to a predetermined high frequency, input means 18 to supply pulses of said frequency, a network 25 and transmission line coupled between the input means 18 and primary coil 12, the network having a variable impedance element and means including a servo loop apparently responsive to patient induced detuning of the circuit to vary the impedance of the element. The apparatus is generally similar to that described in Specification 1,150,524, except that the variable condenser 27 is not adjusted manually, but by an electric motor 73 controlled by the feed-back from an inductance 71 in the head 10 through a servo-loop 70. The loop 70 comprises a pair of band-pass filters 76, 77 feeding a differential amplifier of which the output is fed to the motor 73. The filters are each tuned to a band one on either side of the predetermined frequency of the main circuit so that de-tuning caused by the presence of the patient is picked up by the inductance 71 and the motor 73 is energised to adjust the condenser 27 in such a direction as to restore the system to its original tuning.

Inventors

No inventors recorded.

Bibliographic Details