GB1495391A - Electromedical apparatus - Google Patents

Abstract

1495391 Electromedical apparatus MEDTRONIC INC 6 Dec 1974 [7 Dec 1973 (2)] 52869/74 Heading A5R [Also in Division H4] An electromedical apparatus for the stimulation of a biological system in a living body, comprises a transmitter, Fig. 1, including a pulse-generating circuit for producing at least two pulse trains (3C), (3D), Fig. 3 (not shown), and a body implantable receiver, Fig. 2, including two electrodes 80, 83 and a receiver circuit for applying each of said pulse trains to a respective one of said electrodes. The pulses applied to the electrodes may be non- simultaneous, and their amplitudes are independently adjustable. Square pulses from a pulse generator 10, Fig. 1, at twice the desired stimulation rate are fed to gates 20, 22, a D-flip-flop 26 which alternates high and low at its output terminals q, q for every other input pulse, and a monostable multivibrator 42 triggering either at the leading or trailing edge of the input pulse, the width of the alternate output pulses of the multivibrator being dependent upon the state of the output q for channel identification. The gates 20, 22 let the input pulses through when there is a signal on line 28 or 29 respectively, and the amplitudes of the pulses on lines 31, 32 are varied independently using potentiometers 15, 17. A receiver block 86, Fig. 2, is tuned to receive the pulse trains modulated at a carrier frequency of 455 KHZ whereas a section comprising an inductor 56 and a capacitor 57 develops a 1.5 MHZ signal, the latter being the operating frequency of an oscillator 45. The two pulse trains of different widths on a line 66 operate a latch 88 comprising a comparatively low threshold gate 90, and a gate 91 through the charging of a capacitor 69, to apply each of the pulse trains on a line 70 to its respective electrode 80 or 83. In another embodiment of the transmitter, Fig. 4 (not shown), both the pulse trains are modulated at different carrier frequencies (460 KHZ arid 200 KHZ) and are transmitted through a common antenna 35. In a modification, Fig. 5 (not shown), of the transmitter of Fig. 4, instead of potentiometers 12, 15, 17, a circuit comprising analog switches and potentiometers provides for adjustment of the minimum and the maximum amplitude levels of the pulse trains. In a modified receiver, Fig. 6 (not shown) for use with the transmitters of Fig. 4 or 5, one of two capacitorinductor voltage dividers is resonating with the receiver antenna at a carrier frequency of 460 KHZ and the other at a frequency of 200 KHZ, and each is connected to the respective electrode through blocking diodes. Instead of a RF. link the transmitter and the receiver may be connected directly. The pulse power level may also be controlled by independently regulating the pulse width or pulse shape. When the pulse trains are transmitted on different frequencies, their pulse repetition rates may be controlled independently of each other.