METHODS AND APPARATUS RELATED TO PROTECTION OF A SPEAKER

• US 20140126730A1
• Filed: 11/07/2013
• Published: 05/08/2014
• Est. Priority Date: 11/07/2012
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Fairchild Semiconductor Corporation (ON Semiconductor Corporation)
• Inventors: CRAWLEY, Philip, LLEWELLYN, William D., SHUSHTARIAN, Majid, SCHREYER, Earl D.
• Granted Patent: US 9,729,986 B2
• Time in Patent Office: Days
• US Class Current: 381/59
• CPC Class Codes: H04R 29/001 for loudspeakers H04R29/007 takes precedence

Abstract

In one general aspect, a method can include calculating, at a calibration temperature of a speaker, a calibration parameter through a coil of the speaker in response to a first test signal, and can include sending a second test signal through the coil of the speaker. The method can also include measuring a parameter through the coil of the speaker based on the second test signal, and calculating a temperature change of the coil of the speaker based on the parameter and based on the calibration parameter at the calibration temperature.

Claims

1. An apparatus, comprising:

a temperature sensor configured to measure a calibration temperature of a speaker coil;

a test signal generator configured to generate a first test signal through the speaker coil;

a current detector configured to measure a calibration current at the calibration temperature of the speaker coil based on the first test signal through the speaker coil;

an audio signal generator configured to generate an audio signal; and

a controller configured to trigger sending of a second test signal from the test signal generator through the speaker coil in combination with the audio signal, the current detector configured to calculate a temperature change of the speaker coil during normal operation using a temperature relationship based on the calibration current at the calibration temperature and a temperature coefficient of the speaker coil.

2. The apparatus of claim 1, wherein the first test signal is a first portion of a test signal produced starting at a first time and the second test signal is a second portion of the test signal produced starting at a second time.

3. The apparatus of claim 1, wherein the first test signal and the second test signal are produced using a same oscillator.

4. A method, comprising:

calculating, at a calibration temperature of a speaker, a calibration parameter through a coil of the speaker in response to a first test signal;

sending a second test signal through the coil of the speaker;

measuring a parameter through the coil of the speaker based on the second test signal; and

calculating a temperature change of the coil of the speaker based on the parameter and based on the calibration parameter at the calibration temperature.

5. The method of claim 4, wherein the first test signal has a frequency that is a same as a frequency of the second test signal.

6. The method of claim 4, wherein the first test signal has a triangle waveform.

7. The method of claim 4, wherein the first test signal has a frequency of approximately 4 Hz.

8. The method of claim 4, wherein the calculating includes calculating based on a temperature relationship.

9. The method of claim 4, wherein the calculating includes adding the temperature change of the coil of the speaker to the calibration temperature.

10. The method of claim 4, wherein the calculating includes calculating based on a serialized process.

11. The method of claim 4, wherein the measuring is performed during a portion of a measurement cycle.

12. The method of claim 4, wherein the measuring is performed via a current sense MOSFET device.

13. The method of claim 4, wherein the parameter is at least one of a current, a resistance, or a voltage.

14. A method, comprising:

receiving an indicator of an amplitude of an audio signal associated with a speaker;

determining that the amplitude exceeds a threshold amplitude value;

modifying, for a time period, a time constant of an input filter from a first value to a second value in response to the determining; and

modifying the time constant from the second value to a third value in response to the time period expiring.

15. The method of claim 14, wherein the time constant is a resistor-capacitor (RC) time constant, and the first value is different from the third value.

16. The method of claim 14, wherein the filter is a high-pass filter and is an analog filter, the time constant is decreased from the first value to the second value such that a range of low-end frequencies eliminated by the input filter is increased.

17. The method of claim 14, wherein the modifying includes modifying at a release rate.