Speaker diagnostics based upon driving-point impedance
View Patent ↗A speaker ( 100 ) having a diagnostic capability, as well as a circuit ( 101 ) and related methods ( 500 ) for performing speaker diagnostics based upon a driving-point impedance are provided. The speaker includes a flexible cone ( 104 ) and a voice coil ( 106 ) connected to the flexible cone for driving the flexible cone so as to convert electrical signals into sound. The speaker also includes a signal source ( 110 ) connected to the voice coil for supplying a test signal to the voice coil. The speaker further includes a signal sensor ( 112 ) electrically connected to the voice coil for sensing a response signal occurring in response to the test signal. Additionally, the speaker includes a condition determining module ( 114 ) for determining a driving-point impedance based upon the response signal and for comparing the driving-point impedance to a predetermined impedance to thereby determine a condition of the speaker.
1. A method of ascertaining a condition of a speaker contained in an audio device, the method comprising:
supplying a test signal to a voice coil that drives the speaker;
determining a driving-point impedance from the voice coil based upon the test signal; and
comparing the driving-point impedance to a predetermined impedance to thereby ascertain the condition of the speaker based upon the comparison.
2. The method of claim 1 , wherein the predetermined impedance comprises an impedance profile.
3. The method of claim 1 , wherein the predetermined impedance comprises at least one threshold to which the driving-point impedance is compared.
4. The method of claim 3 , wherein the at least one threshold comprises at least one of a resonance impedance phase zero-crossing, a resonance impedance magnitude, and a resonance infinite-impedance magnitude approximation.
5. The method of claim 1 , wherein supplying a test signal comprises supplying a plurality of test signals, each of the plurality of test signals having a different frequency selected from a range of frequencies.
6. The method of claim 1 , wherein supplying a test signal comprises supplying a low-power broadband signal.
7. The method of claim 1 , further comprising determining if at least one of a voice-coil open, a voice-coil short, and a voice-coil partial short condition exists based upon the comparison.
8. A circuit for determining a condition of a speaker having a voice coil and contained in an audio device, the circuit comprising:
a signal source connected to the voice coil for supplying a test signal to the voice coil;
a signal sensor electrically connected to the voice coil for sensing a response signal occurring in response to the test signal; and
a condition determining module for determining a driving-point impedance based upon the response signal and comparing the driving-point impedance to a predetermined impedance to thereby determine a condition of the speaker.
9. The circuit of claim 8 , wherein the predetermined impedance comprises an impedance profile.
10. The circuit of claim 8 , wherein the predetermined impedance comprises at least one threshold to which the driving-point impedance is compared.
11. The circuit of claim 10 , wherein the at least one threshold comprises at least one of a resonance impedance phase zero-crossing, a resonance impedance magnitude, and a resonance infinite-impedance magnitude approximation.
12. The circuit of claim 8 , wherein the test signal supplied by the signal source comprises a low-power broadband signal.
13. The circuit of claim 8 , wherein the signal supplied by the signal source comprises a plurality of test signals, each of the plurality of test signals having a different frequency selected from a range of frequencies.
14. The circuit of claim 13 , wherein the plurality of test signals are part of a frequency sweep performed by the signal source.
15. The circuit of claim 8 , wherein the signal sensor comprises a current sensor coupled to an analog-to-digital converter for supplying a digital signal to the condition determining module, and wherein the condition determining module is configured to process digital signals.
16. The circuit of claim 14 , wherein the condition determining module is configured to compute an inverse fast Fourier transform.
17. A self-diagnosing speaker for an audio device, the speaker comprising:
a flexible cone;
a voice coil connected to the flexible cone for driving the flexible cone to thereby convert electrical signals into sound;
a signal source connected to the voice coil for supplying a test signal to the voice coil;
a signal sensor electrically connected to the voice coil for sensing a response signal occurring in response to the test signal; and
a condition determining module for determining a driving-point impedance based upon the response signal and comparing the driving-point impedance to a predetermined impedance to thereby determine a condition of the speaker.
18. The self-diagnosing speaker of claim 17 , further comprising an output module in communication with the condition determining module for generating a user-observable output indicating to a user the condition of the speaker.
19. The self-diagnosing speaker of claim 18 , wherein the user-observable output comprises an audio output.
20. The self-diagnosing speaker of claim 17 , wherein the test signal comprises at least one of a plurality of test signals each having a different frequency selected from a range of frequencies and a low-power broadband signal.