Patent ID: 11869470
Assignee: FUJIFILM CORPORATION
Field: Thermal processes and apparatus (Mechanical engineering)
Classification: CPC G  F | IPC F  G

Claim 21:
22. An acoustic system comprising:
a duct that has a function of causing a fluid to flow therein and has a tubular shape;
an internal sound source that is disposed inside the duct or at an outer peripheral portion of the duct, which communicates with an inside of the duct, or an external sound source that is on an outside from an end portion of the duct; and
a membrane-shaped member that is formed as a part of a wall of the duct and vibrates in response to sound,
wherein a structure including the membrane-shaped member and a rear surface thereof causes acoustic resonance to occur, transmits the acoustic resonance from the sound source into the duct, and suppresses sound radiated from the other end portion of the duct,
the external sound source is at a distance within a wavelength at a frequency of the acoustic resonance on the outside from the end portion of the duct,
a rear surface space of the membrane-shaped member is formed by a substantially closed space,
the structure including the membrane-shaped member and the rear surface is a membrane-type resonance structure in which a resonant frequency is determined by the membrane-shaped member and the rear surface space, and
in a case where a Young's modulus of the membrane-shaped member is denoted by E (Pa), a thickness is denoted by t (m), a thickness of the rear surface space is denoted by d (m), and a circle equivalent diameter of a region where the membrane-shaped member vibrates is denoted by Φ (m), hardness E×t3 (Pa×m3) of the membrane-shaped member is 21.6×d−1.25×Φ4.15 or less.