Electrical audio signal processing systems and devices – Stethoscopes – electrical
Patent
1987-06-09
1989-04-11
Isen, Forester W.
Electrical audio signal processing systems and devices
Stethoscopes, electrical
A61B 704
Patent
active
048213276
DESCRIPTION:
BRIEF SUMMARY
SUMMARY OF THE INVENTION
Stethoscopes are largely used in medical applications, but they require a certain amount of skill. Thus, the measuring of the arterial pressure by auscultation can be made with precision. However, one has to take into account the impact of the operator, which is not negligible, on the results of the measurement, such as the auditive acuity, the environmental noise, reaction time etc.. The delicate point is, evidently, the determination of the diastolic pressure.
In certain devices designed for the purpose of a more or less automatic measurement of the arterial pressure, it is known to replace the regulate stethoscope by an electrical unit comprising a pick-up, at least one input filter, an amplifier and a threshold device for the purpose of supplying an electrical signal as soon as the level of the sounds perceived by the electrical pick-up, in a given frequency range, exceeds a predetermined threshold. There are also electrical stethoscopes based on the same principle, but which are not appreciated by the medical profession except for certain applications. In fact, doctors are used to the classical stethoscope and do not like to rely entirely on electrical stethoscopes. This compels them to use two different kinds of stethoscopes.
The aim of the present invention is to eliminate the waste of time resulting from the use of two different kinds of stethoscopes. The object of this invention is a stethoscope comprising an acoustical pick-up and an electrical pick-up, the latter being connected to an amplifier acting upon an electro-acoustical emitter transmitting sounds to the earpieces of the stethoscope, characterized in that the electrical receiver is connected to the emitter by way of a band pass filter, followed by a threshold device supplying a signal to drive the electro-acoustical emitter, the latter being connected to an audible frequency generator which supplies audible sounds as soon as the level of the sounds perceived by the electrical pick-up and included in the range of the passing frequencies of the filter exceeds a well-determined threshold.
The attached drawing represents schematically and by way of example an embodiment and some variants of the stethoscope which is the object of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exterior view of a stethoscope.
FIG. 2 is an synoptic electrical diagram of the electrical unit of this stethoscope.
FIGS. 3 to 5 represent different methods of connecting the electro-acoustic emitter to the conduit of the stethoscope.
DETAILED DESCRIPTION OF THE INVENTION
The stethoscope represented in FIG. 1, just like the regular stethoscopes, contains a capsule 1, covered by a flexible membrane 2 to form an acoustical pick-up. This capsule is connected to a flexible tube or conduit 3, which separates into two branches 4 and 5 ending in two bent tubes 6 and 7, whose upper ends are provided with butts 8 and 9 designed to fit into the auditive channels of the user.
This stethoscope further comprises an electrical unit enclosed in casing 10 which is connected to the acoustical conduit 3. This electrical unit is connected to a piezoelectrical pick-up 11 which is attached to membrane 2 by means of glue. The connection between the electrical unit in causing 10 and pick-up 11 is made by an armored or shielded cable 12 passing through conduit 3 and terminating in a contact plate 14 attached to the wall of capsule 1 and connected to the pick-up by two flexible conductors. Conduit 3 and armored cable 12 are connected to casing 10 by way of connector 13.
FIG. 2 shows the diagram of the electrical unit which is connected to pick-up 11. The signal received from the pick-up is applied to an amplifier 15, then to bandpass filter 16 which strongly attenuates the frequencies below 20 Hz and above 100 Hz. The signals passing through filter 16 are those corresponding to the "Korotkoff noises" and enter into a Schmitt trigger 17 which controls generator 18 designed to apply hythmic sounds reproduced by emitter 19. The power supply to this un
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patent: 3247324 (1966-04-01), Cefaly et al.
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patent: 3651798 (1972-03-01), Egli et al.
patent: 4254302 (1981-03-01), Walshe
patent: 4594731 (1986-06-01), Lewkowicz
Caron Charles
Furugard Erik G.
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