Electrical audio signal processing systems and devices – Audio transducer protection circuitry
Reexamination Certificate
2001-09-07
2008-11-04
Chin, Vivian (Department: 2615)
Electrical audio signal processing systems and devices
Audio transducer protection circuitry
C381S056000, C381S059000, C381S397000, C381S096000, C381S116000, C381S058000
Reexamination Certificate
active
07447318
ABSTRACT:
This invention provides a compensation system capable of compensating for power loss due to the power compression effects of the voice coil as the temperature of the voice coil increases. To compensate for the power compression effect, the invention predicts or estimates the temperature of the voice coil using a thermal-model, and adjusts the estimated temperature according to the cooling effect as the voice coil moves back and forth in the air gap. The thermal-model may be an equivalent electrical circuit that models the thermal circuit of a loudspeaker. With the input signal equating to the voltage delivered to the loudspeaker, the thermal-model estimates a temperature of the voice coil. The estimated temperature is then used to modify equalization parameters. To account for the cooling effect of the moving voice coil, the thermal resistance values may be modified dynamically, but since this cooling effect changes with frequency, a cooling equalization filter may be used to spectrally shape the cooling signal, whose RMS level may be used to modify the thermal resistance values. The invention may include a thermal limiter that determines whether the estimated voice coil temperature is below a predetermined maximum temperature to prevent overheating and possible destruction of the voice coil.
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Hsu, T.S. et al. Temperature prediction of the voice coil of a moving coil loudspeaker by computer simulation. Journal of Acoustical Society of Japan, vol. 21, pp. 57-62, Mar. 2000.
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Button Douglas J.
Williams Paul Robert
Chin Vivian
Faulk Devona E.
Harman International Industries Incorporated
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