| 摘要 |
1,187,314. Muscle stimulators. DYNATONE ELECTRONICS CORP. 31 May, 1968 [9 June, 1967], No. 26162/68. Heading A5R. [Also in Division H3] In a battery powered muscle stimulator control means 20 provides control signals to an electrical switch means 25 coupled to a blocking oscillator 44 so as alternatively to render the switch means in one state in which the switch means inhibits pulse generation by the blocking oscillator and another state in which the switch means causes repetitive pulse generation by the blocking oscillator and an output circuit 60 is provided for amplifying and steepening the leading edges of the output pulses from the blocking oscillator 44, and the output circuit 60 includes a self biassing amplifier 64 which is only rendered capable of amplifying on receipt of a pulse signal from the blocking oscillator. The control signals are obtained from a transistor multivibrator 21 operating at 30 c/s. This turns gating transistor 26 ON and OFF cyclically. When the transistor 26 is ON this allows the blocking oscillator transistor 46 to become conductive and start to oscillate at 60 c/s. The transistor 46 normally being non-conductive due to the biassing network 52, 63 and 56 and OFF state of transistor 26. The output from the blocking oscillator is passed by voltage stepdown transformer 62 to turn ON normally non- conductive transistors 64, 68. The output from these transistors is passed via a voltage step up transformer 72 to output electrodes 73a, 73b which may be of brass. The output circuit amplifies and shapes the output pulses, the derivative action of the transformer inductances providing steep wavefronts. The output voltage may be varied from 60 volts down to allow for individual differences in the sensitivity of facial muscles by a variable resistor associated with the ON-OFF switch 74. A resistor 75 acts as a safety measure when the resistance associated with switch 74 is shorted.
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