Condenser microphone, microphone unit, and blood pressure gauge
First Claim
1. A condenser microphone in which a diaphragm and a backplate are disposed as two opposing electrodes inside a housing having an opening for admitting sound waves in a front surface, whereinan aeration hole is formed in a wall portion that blocks off a back surface of said housing;
- anda sound-absorbing filter having sound absorption characteristics with respect to a frequency band targeted for detection is disposed so as to entirely cover said opening or aeration hole in one of the front surface or back surface of said housingwhen the sound waves are admitted on a front surface and back surface of the housing, air vibrations of the frequency band targeted for detection are being cut on a surface of the diaphragm on a side that the sound-absorbing filter is disposed, while the air vibrations of the frequency band targeted for detection are not being cut on a surface of the diaphragm on a side that the sound-absorbing filter is not disposed; and
air vibrations on the surfaces of the diaphragm other than air vibrations of the frequency band targeted for detection are canceled out, to thereby detect the air vibrations of the frequency band targeted for detection.
1 Assignment
0 Petitions
Accused Products
Abstract
The present invention provides a condenser microphone capable of detecting small sounds (e.g., Korotkoff sounds) with high sensitivity even in environments with variations in pressure, such as cuff pressure. A condenser microphone (10) is disposed as an acoustic sensor for detecting Korotkoff sounds in a communication space reachable by the internal pressure of the cuff of a blood pressure gauge. In the condenser microphone, a diaphragm (13) and a backplate 14) are disposed in the interior of a housing (11), an aeration hole (30) is formed in a wall (11B) that blocks off the housing back surface, and a sound-absorbing element (20) having sound absorption characteristics with respect to a frequency band targeted for detection is disposed on the front surface of a housing (11).
-
Citations
13 Claims
-
1. A condenser microphone in which a diaphragm and a backplate are disposed as two opposing electrodes inside a housing having an opening for admitting sound waves in a front surface, wherein
an aeration hole is formed in a wall portion that blocks off a back surface of said housing; - and
a sound-absorbing filter having sound absorption characteristics with respect to a frequency band targeted for detection is disposed so as to entirely cover said opening or aeration hole in one of the front surface or back surface of said housing when the sound waves are admitted on a front surface and back surface of the housing, air vibrations of the frequency band targeted for detection are being cut on a surface of the diaphragm on a side that the sound-absorbing filter is disposed, while the air vibrations of the frequency band targeted for detection are not being cut on a surface of the diaphragm on a side that the sound-absorbing filter is not disposed; and air vibrations on the surfaces of the diaphragm other than air vibrations of the frequency band targeted for detection are canceled out, to thereby detect the air vibrations of the frequency band targeted for detection. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
- and
Specification