Pick-up head for an electronic stethoscope

Details Pick-up head for an electronic stethoscope Pick-up head for an electronic stethoscope

1998-05-08

2001-11-27

Isen, Forester W. (Department: 2644)

Electrical audio signal processing systems and devices

Stethoscopes, electrical

C600S528000

Reexamination Certificate

active

06324289

ABSTRACT:

The present invention relates to electronic stethoscopes, and more particularly a pick-up head for an electronic stethoscope.
Stethoscopes are utilized within the industry, specially when listening for certain sounds which may indicate defects in machines, but are primarily used in the field of medicine for listening to sounds in connection with special body functions. Of particular interest are sounds in connection with important organs like lungs, heart and veins.
A doctor will often listen for particular sounds among a plurality of sounds received simultaneously. The various sounds often correspond to special frequency bands, and in this connection it is referred to the appended
FIG. 4
which shows sound frequency bands attached to special types of heart diseases. For example, a doctor who is interested in a symptom of the type mitral stenosis, achieves a substantial improvement if frequencies above about 80 Hz can be removed, since sounds having frequencies above 80 Hz in general can be attached to other phenomena than this type of heart constriction.
Various techniques can be utilized for processing the sound frequency ranges desired to be transmitted from the body to the doctor's ear or to a sound recording apparatus. E.g. in the present applicant's own Norwegian patent application no. 95.0495 there is disclosed an electronic apparatus having an adjustable bandpass filter for removing undesired frequencies, i.e. removing “noise” so as to transmit only sounds of interest for the particular diagnosis in question. However, it is also possible to attack the problem of frequency-shaping and adaptation of sound frequencies already in the microphone itself, or in the pick-up part of the stethoscope. Ordinary stethoscopes without electronic amplification have already been provided with special pick-up head designs for achieving attenuation/amplification of different frequency bands, e.g. GB 2,051,584A and U.S. Pat. No. 4,903,794, both of which disclose stethoscope pick-up heads having special chambers designed to provide resonance at certain frequencies. In both these publications, the sound pick-up head has a forward diaphragm shaped with a centrally situated, forward protruding tip for direct engagement against a body surface.
Stethoscopes of the electronic type, i.e. having acousto-electrical transducers, and of a type somewhat related to the present invention as to design, are previously known from DE 2,703,781, DE 2,453,926 and DE 932,268. DE 2,703,781 discloses a body sound pick-up device having a piezoelectric member. For transmission of vibrations to this member, there is arranged a central and protruding pin in a cylindrical opening. The purpose is to avoid receiving of sound via the air. No measure for shaping the frequency of picked up sound, can be found.
DE 2,453,926 shows an electronic stethoscope wherein the sound pick-up member has a forward diaphragm having a centrally situated, forward protruding “scull cap”. However, sound vibrations are transmitted further through an air space inside the diaphragm to an inside mounted microphone member. Special features for emphasizing/attenuating certain frequency bands are not mentioned.
DE 932,268 discloses a microphone for picking up body sounds, where a center peg transmits vibrations from a body surface to an acousto-electrical converter via a quasi-rigid mechanical connection. The center peg is surrounded by a forward projecting circular edge which has as its purpose to provide an approximately constant engagement force for the center peg against the skin. No means can be found for influencing the transmitted sound regarding removal of undesired sounds and undesired frequencies.
The object of the present invention is to provide a sound pick-up head for use as a part of an electronic stethoscope, where particularly interesting frequency ranges for special diagnosis purposes are emphasized by means of the pick-up head construction itself, at the sacrifice of other frequency ranges.
In accordance with the invention, the object is achieved by providing a sound pick-up head of the type which is defined precisely in the appended patent claims. Thus, the central feature of the invention is that at least one slender peg for conveying vibrations is arranged centrally inside a sound-affecting bell which delimits with its edge a reflection and/or absorption space surrounding the slender peg, in such a manner that certain frequencies are reflected in toward the peg, and other frequencies are prevented from such reflection, whereby the peg conveys frequency-shaped sound. The bell itself is acoustically decoupled from the slender peg, which in itself picks up sound only from a very small area of the body surface, while sound supplied to the peg secondarily after reflection inside the bell, in principle originates from the larger, bounded body surface area under the bell.


REFERENCES:
patent: 3790712 (1974-02-01), Andries
patent: 5812678 (1998-09-01), Scalise et al.
patent: 5931792 (1999-08-01), Packard et al.
patent: 6026170 (2000-02-01), Dieken et al.
patent: 932268 (1955-08-01), None
patent: 2703781 (1978-08-01), None
patent: 501819 (1939-03-01), None

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