Evaluating Validity (Obviousness) over Prior Art Capacitive Microphone in Stethoscope (‘849 patent, filed 1992) Capacitive Touch Sensor (‘389 patent, filed 1997) Prior Art 1Prior Art 2 +
Patented Technology (‘854) 4 Movable, Flexible Diaphragm Electrically Conductive Surface of Diaphragm Electric Field Electrically Conductive Plate Attachment Means to Mount to Housing
Claim 13 An electronic stethoscope including an acoustic-to-electrical transducer for detecting body sounds, the transducer comprising: -a stethoscope diaphragm having an electrically conductive surface, the diaphragm being mounted in a stethoscope chestpiece such that the diaphragm can contact the body for body sound detection and vibrate in response to body sounds; -a fixed conductive plate substantially parallel to the diaphragm, mounted within the chestpiece, the conductive plate being positioned at a distance about or exceeding 0.5 mm from the diaphragm, the diaphragm conductive surface and fixed conductive plate forming two plates of a capacitor and connected in the form of an electrical capacitance to electrical circuitry; -a capacitance-to-electrical signal conversion means to convert diaphragm-plate capacitance changes due to body sound vibrations to electrical signals; -the stethoscope further comprising signal amplification means and at least one electrical-to-acoustic transducer connected to signal amplification means, to reproduce body sounds as detected by said transducer.
What is a capacitive sensing? + + + + - - - - Mechanical Signal Electrical Signal
Prior Art 1 – Microphone inside Stethoscope Capacitive Microphone in Stethoscope (‘849 patent, filed 1992) Prior Art 1
Brief History of Stethoscopes 1816 Monaural 1851 Binaural 1926 Bell/Diaphragm Modes 1962 Electronic Stethoscope with Piezo-electric Sensor 1986 Electronic Stethoscope with Hydrophone Sensor 1992 Electronic Stethoscope with Microphone 1999 ‘854 Patent Filed (Time-line NOT drawn to scale)