STETHOSCOPE

• US 3,555,187 A
• Filed: 12/19/1966
• Issued: 01/12/1971
• Est. Priority Date: 12/19/1966
• Status: Expired due to Term

• Current Assignee: Donald G. Rowley
• Original Assignee: Donald G. Rowley
• Inventors: Rowley, Donald G.
• Application Number:
  US04/613,061
• Time in Patent Office: 1,485 Days
• US Class Current: 600/528
• CPC Class Codes: A61B 2562/0204 Acoustic sensors
• CPC Class Codes: A61B 7/04 Electric stethoscopes microphones, acoustic transducers therefor H04R
• CPC Class Codes: H04R 1/46 Special adaptations for use as contact microphones, e.g. on musical instrument, on stethoscope throat mountings H04R1/14
• CPC Class Codes: H04R 11/04 Microphones

Abstract

The stethoscope is characterized by a housing having an external body contact membrane. A pickup plate is mounted in the housing near the membrane. An electromagnetic coil and armature are mounted on a support plate in the housing. The armature is mounted on the side of support plate opposite to the pickup plate and is connected to the pickup plate so that vibrations detected by the pickup plate are transmitted to the armature. In this way, when the body contact membrane is pressed against the body of a person, with sufficient force to contact the skin clothing interface, the armature is forced away from the electromagnetic coil so it can vibrate freely. With this arrangement the maximum sensitivity of the transducer coincides with the optimum acoustical matching between the body and the transducer.

Claims

1. In a stethoscope of the class described, a housing, a body contact membrane mounted on said housing for engaging the body of a patient, a support plate in said housing, a transducer mounted on said support plate, said support plate connected to said housing through a compliant bearing to isolate the transducer from housing vibrations, said transducer including a vibratory part, a portion of said vibratory part positioned near said body contact membrane such that only when said body contact membrane is pressed against the body of a patient said body contact membrane engages said portion of said vibratory part and causes said transducer to generate electrical vibrations, compliant means interposed between said vibratory part and said support plate in such a way that when the body contact membrane is pressed against the body of a patient, the compliance of the compliant means varies in accordance with the pressure whereby the resonant frequency of the transducer may be varied so that the stethoscope will be more sensitive in the frequency range of interest.

2. In a stethoscope of the class described, a housing, a body contact membrane mounted on said housing for engaging the body of a patient, a compliant bearing mounted on said housing, a support plate mounted on said compliant bearing, a transducer including an electromagnetic coil mounted on said support plate whereby the transducer is isolated by said compliant bearing from housing vibrations, a compliant pressure block bonded at one surface to said support plate, a contact pressure pickup plate, the surface of said compliant pressure block opposite to said one surface bonded to said contact pressure pickup plate, the thickness of said compliant pressure block selected to position said pickup plate close to said body contact membrane such that when pressure is exerted on said body contact surface said body contact membrane is forced into engagement with said pickup plate, an armature associated with said electromagnetic coil, said pickup plate connected to said armature in such a way that sound detected by said pickup plate causes said pickup plate and said armature to vibrate, the compliance of said compliant bearing block varying in accordance with the pressure exerted on said pickup plate whereby the resonant frequency of the transducer may be varied so that the stethoscope will be more sensitive in the frequency range of interest.

3. An apparatus of the class described comprising a housing, a body contact membrane mounted on the housing for engaging the body of a patient, a compliant bearing mounted in said housing, a support plate mounted on said compliant bearing, a transducer including an electromagnetic coil and an armature, said electromagnetic coil mounted on said support plate, a compliant pressure block bonded at one surface to said support plate, a contact pressure pickup plate secured to the surface of said compliant pressure block opposite to said bonded surface, the thickness of said pressure block selected to position said pickup plate adjacent to said body contact membrane whereby when pressure is exerted on said body contact membrane, it is forced into contact with said pickup plate, said pickup plate connected to said armature and positioning said armature on the opposite side of said support plate with respect to said pickup plate, whereby the pressure on said body contact membrane is transmitted to said armature opposing the magnetic force actiNg on said armature, said armature positioned so it is not free to vibrate until the body contact membrane is pressed against the body of a patient with sufficient force to compact the flesh, and/or clothing transducer interface to achieve acoustical matching between the body and the transducer for more efficient reception of sound from the body or transmission of sound to the body, whereby the maximum sensitivity of the apparatus generally coincides with the optimum acoustical matching between the body and the transducer.

4. An apparatus of the class described, comprising a housing, a body contact membrane mounted on the housing for engaging the body of a patient, a compliant bearing mounted in said housing, a support plate mounted on said compliant bearing, a transducer including an electromagnetic coil mounted on said support plate, whereby the transducer is isolated by said compliant bearing from impact damage, a compliant pressure block, one surface of said pressure block secured to said support plate, a contact pressure pickup plate, the opposite surface of said pressure block engaging and secured to said pickup plate, the thickness of said compliant bearing selected to position said pickup plate close to said body contact membrane so that when pressure is exerted on said body contact membrane said body contact membrane is forced into the engagement with said pickup plate, an armature associated with said electromagnetic coil, said pickup plate connected to said armature in such a way that vibrations are transmitted between the pickup plate and the armature.

5. An apparatus of the class described comprising a housing, a body contact membrane mounted on the housing for engaging the body of a patient, a support plate mounted on the said body, a transducer mounted on said support plate, said transducer including an electromagnetic coil and an armature, said armature positioned on the opposite side of said support plate with respect to said body contact membrane, means connecting said body contact membrane with said armature in such a way that force exerted on said body contact membrane is transmitted to said armature opposing the magnetic force acting on said armature, said armature positioned so it is adjacent the electromagnetic coil whereby the armature is restricted from vibration due to the clamping effect of the magnetic force holding the armature against the coil until the body contact membrane is pressed against the body of a patient whereby the force of said contact transmitted through said connecting means to said armature opposes the magnetic force exerted on said electromagnetic coil permitting the armature to vibrate, said connecting means connected to said armature in such a way that said armature is not free to vibrate until the body contact membrane is pressed against the body of a patient with sufficient force to compact the flesh for more efficient reception of sound from the body or transmission of sound to the body whereby the maximum sensitivity of the apparatus generally coincides with the optimum acoustical matching between the body and the transducer.