Acoustic apparatus for preventing howling
AssigneeAlps Electric Co., Ltd.
InventorShinichi Higuchi
Life of this patent
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Abstract
When a sound signal is received, a sound wave generated on an upper surface of a vibration plate is transmitted to a sound collection portion through a first air passage, and a sound wave generated on a lower surface of the vibration plate is transmitted to the sound collection portion through a second air passage. The sound waves generated above and below the upper and lower surfaces of the vibration plate are about 180 degrees out of phase from each other and substantially cancel each other which minimize or prevent howling.
Claims10
An acoustic apparatus comprising a sound generation portion comprising a vibration plate and a vibration generation portion that drives said vibration plate, and a sound collection portion responsive to an external sound pressure, comprising:
- a first sound pressure transmission portion that transmits a sound pressure generated from a first side of said vibration plate to said sound collection portion when said vibration plate generates sound;
- and
- a second sound pressure transmission portion that transmits a sound pressure generated from a second side of said vibration plate to said sound collection portion when said vibration plate generates sound.
An acoustic apparatus comprising:
- a support;
- a sound generation portion comprising a first vibration plate for generating sound, a driving coil for vibrating said first vibration plate, and a magnetic circuit for generating a magnetic field crossing said driving coil;
- a sound collection portion coupled to said support comprising a second vibration plate for collecting sound, a detection coil operating with said second vibration plate, and a magnetic circuit for generating a magnetic field crossing said detection coil;
- and
- an auxiliary coil coupled to said support that vibrates with said first vibration plate during a sound generation caused by vibration of said first vibration plate, and a current circuit including said detection coil and said auxiliary coil;
- wherein said current circuit is configured to receive an induced current in said auxiliary coil when the sound generation operation of said first vibration plate vibrates and which said second vibration plate substantially cancels said induced current generated in said auxiliary coil.
Dependencies are inferred from the claim text.