US4438772A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Differential stethoscope
Assignee: Advanced Medical Electronics Developments LP
•
Filing: 1982-04-08
•
Granted: 1984-03-27
•
Expires: 2002-04-08
Abstract
Abstract A portable differential stethoscope includes small microphone elements which are attached to the stethoscope heads to pick up acoustic signals from the body. The sounds picked up by the stethoscope heads include body noise signals as well as heartbeat signals. Each stethoscope head and microphone element provides an output which is amplified in an individual amplifier. The two amplified signals are inputted to separate terminals of a differential amplifier through a gain and balance control element. The differential amplifier outputs a difference signal which is amplified and inputted to an electrical headset or an electrical earphone element which is acoustically coupled to the conventional acoustic tube.
Inventors
- 👤 Martin J. Slavin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 14:01
CPC Classifications
A; A61; A61B; A61B7/00; A61B7/02; A61B7/04
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
135 words
A portable stethoscope for listening to internal sounds of a body comprising: first and second sensor means for selective application at two selectively and variably spaced portions of the external surface of said body and for detecting said internal sounds and outputting electrical signals in response to said sounds, said sound signals including a first signal desired for detection and a second undesired signal, said first signal being masked by said second signal; comparison means for receiving said electrical signals from said first and second sensor means and outputting a comparison signal, said comparison signal being the difference between concurrently received electrical signals from said first and second sensor means; output means receiving said comparison signal and outputting a sensible signal, said sensible signal corresponding to said difference comparison signal of said detected sound signals.
Claim 2
Dependent Claim
135 words
A portable stethoscope for listening to internal sounds of a body comprising: first and second sensor means for selective application at two selectively and variably spaced portions of the external surface of said body and for detecting said internal sounds and outputting electrical signals in response to said sounds, said sound signals including a first signal desired for detection and a second undesired signal, said first signal being masked by said second signal; comparison means for receiving said electrical signals from said first and second sensor means and outputting a comparison signal, said comparison signal being the difference between concurrently received electrical signals from said first and second sensor means; output means receiving said comparison signal and outputting a sensible signal, said sensible signal corresponding to said difference comparison signal of said detected sound signals.
Claim 3
Dependent Claim
24 words
A stethoscope as claimed in claim 1, wherein said first signal is a heartbeat signal and said second signal is derived from body noises.
Claim 4
Dependent Claim
36 words
A stethoscope as claimed in claim 2, and further comprising first and second amplifier means for receiving said electrical signals from said first and second sensor means respectively and inputting amplifier signals to said comparison means.
Claim 5
Dependent Claim
17 words
A stethoscope as claimed in claim 1 or 2, wherein said comparison means is a differential amplifier.
Claim 6
Dependent Claim
36 words
A stethoscope as claimed in claim 4, and further comprising first and second amplifier means for receiving said electrical signals from said first and second sensor means respectively and inputting amplified signals to said comparison means.
Claim 7
Dependent Claim
29 words
A stethescope as claimed in claim 5, and further comprising third amplifier means for amplifying said comparison signal, said amplified comparison signal being inputted to said sensible output means.
Claim 8
Dependent Claim
24 words
A stethoscope as claimed in claim 6, and further comprising control means for independently varying the gain of said first and second amplifier means.
Claim 9
Dependent Claim
28 words
A stethoscope as claimed in claim 7, wherein said first and second sensor means include acoustic heads and microphone means for converting acoustic signals to said electrical signals.
Claim 10
Dependent Claim
23 words
A stethoscope as claimed in claim 8, wherein said sensible output means produces at least one of an audible, visual and electrical output.
Claim 11
Dependent Claim
43 words
A stethoscope as claimed in claim 9, wherein said sensible output is audible and said output means includes one of an electrical headset and an acoustic tube with earpieces, said acoustic tube and headset being driven in response to said amplified comparison signal.
Claim 12
Dependent Claim
28 words
A stethoscope as claimed in claim 5, and further comprising band width filter means for passing said first signal and blocking at least in part said second signal.
Claim 13
Dependent Claim
35 words
A stethoscope as claimed in claim 11, wherein said second signal includes high frequencies than does said first signal, said first and second amplifier means being operational amplifiers having feedback loops including selectively variable capacitance.
Claim 14
Dependent Claim
23 words
A stethoscope as claimed in claim 12, wherein said variable capacitances of said first and second operational amplifiers are ganged for simultaneous adjustment.
Claim 15
Independent Claim
92 words
A method of separating heartbeat sounds from a signal dominated by noise, comprising the steps: (a) simultaneously sensing combined heartbeat and internal noise signals at a first and a second selectively variable external body location, said heartbeat signals being of different amplitude at said first and second locations; (b) subtracting, one from the other, said combined signals from said first and second body locations; (c) outputting the difference signal produced in step b, said difference signal being dominated by the difference in said heartbeat signals from said first and second body locations.
Claim 16
Independent Claim
92 words
A method of separating heartbeat sounds from a signal dominated by noise, comprising the steps: (a) simultaneously sensing combined heartbeat and internal noise signals at a first and a second selectively variable external body location, said heartbeat signals being of different amplitude at said first and second locations; (b) subtracting, one from the other, said combined signals from said first and second body locations; (c) outputting the difference signal produced in step b, said difference signal being dominated by the difference in said heartbeat signals from said first and second body locations.
Claim 17
Dependent Claim
34 words
A method as claimed in claim 14, and further comprising the steps: (1) independently amplifying said signals sensed in step (a); (2) prior to step (c), amplifying said difference signal produced in step (b).
Claim 18
Dependent Claim
37 words
A method as claimed in claim 15, and further comprising the step: (3) independently varying the amplified gain of said signals sensed in step (a) to maximize said heartbeat difference signal relative to said noise difference signal.
References Cited (Backward Citations)
US2902108A
Cited
US3020971A
Cited
US3124211A
Cited
US3126553A
Cited
US2748202A
Cited
US3103009A
Cited
US3109508A
Cited
US3547104A
Cited
US3605012A
Cited
US3821948A
Cited
US3848586A
Cited
US4195360A
Cited
US3978856A
Cited
US4005701A
Cited
US4065789A
Cited
US4220926A
Cited
US4194511A
Cited
US4200109A
Cited
US4261369A
Cited
US4250889A
Cited
DE3011770A1
Cited
US4263919A
Cited
US4304240A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-03-27 | 1987-09-26 | 1988-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-27 | 1991-09-26 | 1992-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-27 | 1995-09-26 | 1996-03-27 | $7700.00 | Window Closed / Lapsed |