Telemetering capsule for physiological measurements

摘要

999, 858. Measuring electrically. NIPPON ELECTRIC CO. Ltd. Aug. 7, 1962, [Oct. 6, 1961], No.30243/62. Heading G1N. [Also in Division H4] An endo-radio sonde, which has no built-in power supply, but has a tank circuit for receiving an external h.f. signal, a storage capacitor for storing the rectified signal and which operates as a power source for the initiation of oscillation in the tank circuit after interruption of the external signal is characterized in that the oscillation initiation time is controlled by the tank circuit capacitance or inductance which is made dependent on the physical parameter to be measured. Fig. 2 shows a Hartley oscillator circuit containing a transistor 4 and a tank circuit with coils 11 and 2SP1/SP and capacitor 3. On reception by the tank circuit of an external h.f. signal, the rectifying action of transistor 4 charges base storage capacitor 5 and collector capacitor 6. The charging voltage of capacitor 5 is suppressed to a constant value by a Zener diode 7 connected across it while the voltage across capacitor 6 also attains a constant value which is dependent on the inductance ratio of coils 1SP1/SP and 2SP1/SP. On interruption of the h.f. signal, storage capacitor 5 discharges, transistor 4 is shifted from cut-off position and the tank circuit begins to oscillate. Since capacitors 5 and 6 are connected by resistor 9, the oscillation initiation time is dependent on the voltage across capacitor 6 and hence on the inductance ratio of coils 1SP1/SP and 2SP1/SP. By causing the iron core of one of these coils to change position with pressure, telemetering of gastrointestinal pressures can be implemented. An alternative circuit embodying a Colpitts oscillator is described in which the pressure sensitive component is a capacitor. Reference has been directed by the Comptroller to Specification 906,006.