Loudspeaker with motional feedback
AssigneeVelodyne Acoustics, Inc.
InventorDavid S. Hall
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Abstract
Improvements in a moving-coil loudspeaker system of the type incorporating motional feedback. An accelerometer mounted on the loudspeaker coil to develop the feedback signal is enclosed within an air-tight shield can to avoid low-frequency instability. High-frequency stability is enhanced by various means including use of a "trumpet" shaped speaker cone, an inverted (concave) dust cap, and theta-dependent cone variations such as providing clusters of holes through the speaker cone to alter the propagation of sound waves radially in selected sectors of the cone. Also disclosed is the use of weights placed on the loudspeaker coil in selected locations circumferentially with respect to the accelerometer to minimize instability effects.
Claims23
In a loudspeaker of the moving-coil type, the combination of:
- a motional transducer element secured to the moving coil of said loudspeaker;
- negative feedback means coupled to said transducer to combine the transducer signal with a loudspeaker audio signal to form a closed feedback loop;
- an amplifier having its input coupled to the composite of transducer and audio signals, the output of said amplifier driving said moving coil;
- and
- air-tight housing means containing said motional transducer element to prevent external pressure variations from affecting the functioning of said transducer element.
In a loudspeaker of the moving-coil type, the combination of:
- a motional transducer element secured to the moving coil of said loudspeaker;
- negative feedback means coupled to said transducer to combine the transducer signal with a loudspeaker audio signal to form a closed feedback loop;
- an amplifier having its input coupled to the composite of transducer and audio signals, the output of said amplifier driving said moving coil;
- and
- a cone secured to the moving coil of said loudspeaker for converting coil movement into sound pressure signals, said cone having a configuration in longitudinal cross-section which is convexly curvilinear as viewed from the interior of the cone, thereby presenting a trumpet-shaped appearance.
In a loudspeaker of the moving-coil type, the combination of:
- a motional transducer element secured to the moving coil of said loudspeaker;
- negative feedback means coupled to said transducer to combine the transducer signal with a loudspeaker audio signal to form a closed feedback loop;
- an amplifier having its input coupled to the composite of transducer and audio signals, the output of said amplifier driving said moving coil;
- and
- a cone secured to the moving coil of said loudspeaker for converting coil movement into sound pressure signals, said cone comprising a plurality of radial sectors adjacent ones of which have different sound propagation properties.
In a loudspeaker of the moving-coil type, the combination of:
- a motional transducer element secured to the moving coil of said loudspeaker;
- negative feedback means coupled to said transducer to combine the transducer signal with a loudspeaker audio signal to form a closed feedback loop;
- an amplifier having its input coupled to the composite of transducer and audio signals, the output of said amplifier driving said moving coil;
- and
- a dust cap at the center of said cone, said dust cap having a concavely contoured configuration.
In a loudspeaker of the moving-coil type, the combination of:
- a motional transducer element secured to the moving coil of said loudspeaker;
- negative feedback means coupled to said transducer to combine the transducer signal with a loudspeaker audio signal to form a closed feedback loop;
- an amplifier having its input coupled to the composite of transducer and audio signals, the output of said amplifier driving said moving coil;
- and
- at least one weight positioned on said coil, circumferentially displaced from said transducer element, to reduce instability.
Dependencies are inferred from the claim text.