Noise canceling solid state electronic stethoscope with adapted acoustic impedance
OwnerRodolfo Jose Miccinoinventor
Life of this patent
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Abstract
A solid-state electronic stethoscope with ambient noise cancellation and active noise cancellation technique. In a first embodiment, the improved signal-to-noise ratio is obtained by applying an acoustic impedance matching technique. In a second embodiment, the stethoscope further comprises an arrangement of additional sensors for active noise cancellation based on a differential acoustic signal technique.
Claims20
A solid state stethoscope, comprising an outer membrane (1a) for contacting the skin of a patient, an upper inner conductive cover (7b) located below said outer membrane (1a), a lower conductive cover (2), an acoustic coupler (3), a sensor sheet (4), a rear plate (5) located below the sensor sheet (4) and resting on a cylindrical backrest (6), a printed circuit board PCB (16) located under said cylindrical backrest (6),
- wherein said outer membrane (1a) is made of TPU (thermoplastic polyurethane) or silicone and comprises a lower spherical central member (1b), said sheet sensor (4) is made of Piezo PVDF (polyvinylidene fluoride or vinylidene polyfluoride) with silver micrometallic electrodes and has a rectangular perimeter shape with a curved central zone (4a) and flat sides, and
- wherein the stethoscope comprises the acoustic coupler (3), the acoustic coupler (3) being made of flexible polyurethane and having a flat upper face (3a) in contact with the lower spherical central member (1b) and a curved lower face (3b) resting on the sensor sheet (4),
- wherein a path of an acoustic signal formed by said outer membrane (1a), said lower spherical central member (1b), said acoustic coupler (3) and said sensor sheet (4) has an acoustic impedance similar to that of the skin of said patient, thus being capable of generating an acoustic impedance adaptation between said skin and said sensor sheet (4), achieving optimal sensitivity and maximum rejection of environmental noise.
A solid state stethoscope, comprising an outer membrane (8b) in a central area of a cylindrical cap (8) for contacting the skin of a patient, an upper inner conductive cover (9) located below said outer r membrane (8b), a lower conductive cover (15), a central sensor sheet (11) for capturing auscultated signal and two lateral sensor sheets (11a, 11b) for capturing unwanted noise, a rear plate (12) located below the two lateral sensor sheets (11a, 11b) and resting on a cylindrical backrest (13), a printed circuit board PCB (14) comprising electronic circuits located below said cylindrical backrest (13),
- wherein said outer membrane (8b) is made of TPU (thermoplastic polyurethane) or silicone and comprises a central spherical lower member (8c), said central sensor sheet (11) and said lateral sensor sheets (11a, 11b) each have a rectangular perimeter shape with a curved central area (11c) and flat sides, and wherein the stethoscope also comprises a central acoustic coupler (10) placed on said central sensor sheet (11) and in close contact therewith, and also comprises two lateral acoustic couplers (10a, 10b) each placed on a corresponding lateral sensor sheet (11a, 11b), in close contact therewith and fixed by said upper inner conductive cover (9), and
- wherein the central acoustic coupler (10) and the lateral acoustic couplers (10a, 10b) are made of flexible polyurethane and each have a flat upper face, and wherein the flat upper face of the central acoustic coupler (10) is in contact with the central spherical lower member (8c) of the outer membrane (8b), and the flat upper face of each of the lateral acoustic couplers (10a, 10b) is in contact with a corresponding lateral spherical lower member (8a) of a lateral area of the cylindrical cap (8), and
- wherein the central acoustic coupler (10) has a curved lower face resting on the central sensor sheet (11) and each of the lateral acoustic couplers (10a, 10b) has a curved lower face resting on a corresponding lateral sensor sheet (11a, 11b), where said central sensor sheet (11) and said lateral sensor sheets (11a, 11b) are made of Piezo PVDF (polyvinylidene fluoride or vinylidene polyfluoride) with silver micrometallic electrodes,
- whereby a path of an acoustic signal formed by said outer membrane (8b), said central spherical lower members (8c), said central acoustic coupler (10) and said central sensor sheet (11), and the path of the acoustic signal formed by said outer membrane (8b), said lateral spherical lower members (8a), said lateral acoustic couplers (10, 10b) and said lateral sensor sheets (11a, 11b), have an acoustic impedance similar to that of the skin of said patient, thus capable of generating an acoustic impedance adaptation between said skin and said central sensor sheet (11) and an acoustic impedance match between said skin and said lateral sensor sheets (11a, 11b);
- and
- wherein, in the electronic circuits an amplified signal from the central sensor (11) is added to an inverted polarity signal from both lateral sensor sheets (11a, 11b) to obtain a differential acoustic signal, by which the stethoscope is capable of canceling unwanted noise signals captured by said lateral sensors (11a, 11b) and leaving only desired signals coming from an auscultated area taken by the central sensor sheet (11).
Dependencies are inferred from the claim text.