| 摘要 |
1,241,924. Electro-medical apparatus. PHILLIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. Dec.1, 1969 [Dec.4, 1968], No.58513/69. Heading G1N. [Also in Division A5] In apparatus for monitoring the strength of electro-physiological signal, e.g. as shown E. C. G. signals, an audio-frequency carrier wave from an oscillator 5 is frequency-modulated by the signal voltage from an E.C.G. amplifier 4, the tone strength of the frequency-modulated carrier wave being varied in accordance with the strength of the signal voltage, from amplifier 4 and a rectifier 8, by an amplitude modulator 9 whose output is applied to a sound reproducer 11 via variable gain amplifier 10. The modulation level may be adjusted so that with no input signal the output sound is below the limit of audibility. The circuitry is contained in a casing 12 having input electrodes 13, 14, and 15 (corresponding to electrodes 1, 2, 3, in Fig.1), a button 16 for operating the switch 6 in Fig.1, and a dial 17 for varying the gain of amplifier 10. Slots 18 provide a sound outlet. |
