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US 9,794,687 B2Granted
Loudspeaker protection circuitry and methods
AssigneeCirrus Logic, Inc.
InventorsRoberto Napoli, Jason William Lawrence
Life of this patent
Estimating the term…
Abstract
This application relates to methods and apparatus for thermal protection of a loudspeaker (102). A controller (106) is configured to generate a control signal (Gmod) for modulating the gain of a signal processing chain (101) that drives the loudspeaker. The controller is configured such that the control signal is generated as a function of each of: an indication of voice coil temperature of the loudspeaker (TVC); an indication of power dissipation in the voice coil of the loudspeaker (PVC); and an indication of a reservoir temperature (Tres) of a thermal reservoir for heat flow from the voice coil. The reservoir temperature may be an ambient temperature of the environment or a temperature of a component of the loudspeaker or apparatus that acts as a heat sink.
Claims27
A system for thermal protection of a loudspeaker comprising:
- a controller configured to generate a control signal for modulating the gain of a signal processing chain driving said loudspeaker,
- wherein said controller is configured such that the control signal is generated as a function of each of:
- an indication of voice coil temperature of the loudspeaker;
- an indication of power dissipation in the voice coil of the loudspeaker;
- and
- an indication of a reservoir temperature of a thermal reservoir for heat flow from the voice coil, and
- wherein the controller is configured to receive a signal obtained by monitoring a voltage applied to the loudspeaker and a signal obtained by monitoring a current in the loudspeaker,
- wherein the controller is configured to use said received signals to obtain at least one of the indication of voice coil temperature of the loudspeaker, the indication of power dissipation in the voice coil of the loudspeaker, and the indication of a reservoir temperature of a thermal reservoir for heat flow from the voice coil, and
- wherein the controller comprises:
- a power limit module configured to determine an allowed power function of an allowed power dissipation with voice coil temperature based on said indication of a reservoir temperature;
- and
- a gain calculation module configured to determine a gain setting based on the indication of power dissipation in the voice coil and the allowed power function, and
- wherein said control signal is based on said gain setting.
10 more elements
A system for thermal protection of a loudspeaker comprising:
- a controller configured to generate a control signal for modulating the gain of a signal processing chain driving said loudspeaker,
- wherein said controller is configured such that the control signal is generated as a function of each of:
- an indication of voice coil temperature of the loudspeaker;
- an indication of power dissipation in the voice coil of the loudspeaker;
- and
- an indication of a reservoir temperature of a thermal reservoir for heat flow from the voice coil,
- wherein the controller comprises:
- a power limit module configured to determine an allowed power function of an allowed power dissipation with voice coil temperature based on said indication of a reservoir temperature;
- and
- a gain calculation module configured to determine a gain setting based on the indication of power dissipation in the voice coil and the allowed power function,
- wherein said control signal is based on said gain setting.
8 more elements
A system for thermal protection of a loudspeaker comprising:
- a controller configured to generate a control signal for modulating the gain of a signal processing chain driving said loudspeaker,
- wherein said controller is configured such that the control signal is generated as a function of each of:
- an indication of voice coil temperature of the loudspeaker;
- an indication of power dissipation in the voice coil of the loudspeaker;
- and
- an indication of a reservoir temperature of a thermal reservoir for heat flow from the voice coil,
- further comprising an estimation module configured to determine said indication of reservoir temperature based on said indication of power dissipation of the voice coil,
- wherein the estimation module comprises:
- a temperature rise module configured to determine an estimated temperature rise based on the indication of power dissipation of the voice coil and a thermal impedance model of a thermal path between the voice coil and the thermal reservoir;
- and
- a reservoir temperature estimation module configured to determine the indication of reservoir temperature based on the indication of voice coil temperature and the estimated temperature rise.
8 more elements
A system for thermal protection of a loudspeaker comprising:
- a controller configured to generate a control signal for modulating the gain of a signal processing chain driving said loudspeaker,
- wherein said controller is configured such that the control signal is generated as a function of each of:
- an indication of voice coil temperature of the loudspeaker;
- an indication of power dissipation in the voice coil of the loudspeaker;
- and
- an indication of a reservoir temperature of a thermal reservoir for heat flow from the voice coil;
- further comprising an estimation module configured to determine said indication of reservoir temperature based on said indication of power dissipation of the voice coil,
- wherein the estimation module comprises at least one input for receiving a first signal indicative of voltage applied to the voice coil of said loudspeaker and a second signal indicative of current flowing in said voice coil and is configured to determine said indication of temperature of the voice coil and said indication of power dissipation in the voice coil based on said first and second signals;
- wherein at least said indication of voice coil temperature of the loudspeaker is based on an estimate of resistance of said voice coil which is determined based on said first and second signals.
6 more elements
A thermal protection system for a loudspeaker comprising:
- at least one input for receiving a first signal indicative of voltage applied to the voice coil of said loudspeaker and a second signal indicative of current flowing in said voice coil;
- a temperature and power estimation module configured to determine:
- an estimate of temperature of the voice coil based on an estimate of resistance of said voice coil which is determined based on said first and second signals;
- an estimate of power dissipation in the voice coil based on said first signal, second signals and/or said estimate of resistance of said voice coil;
- and
- an estimate of temperature of a thermal reservoir for heat produced in the voice coil based on a comparison of said estimate of temperature of the voice coil the voice coil and an estimate of rise of coil temperature based on a thermal speaker model and said estimate of power dissipation in the voice coil;
- a gain controller configured to generate a gain control signal for modulating the gain of a signal processing chain driving said loudspeaker, wherein said gain control signal is generated as a function of each of said estimate of temperature of said voice coil, said estimate of power dissipation in the voice coil and said estimate of temperature of a thermal reservoir.
4 more elements
Dependencies are inferred from the claim text.