Speaker diagnostics based upon driving-point impedance

• US 7,106,865 B2
• Filed: 12/15/2004
• Issued: 09/12/2006
• Est. Priority Date: 12/15/2004
• Status: Expired due to Fees

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Yeager, David M., Pavlov, Peter M., McIntosh, Jason D.
• Primary Examiner(s): Chin, Vivian
• Assistant Examiner(s): KURR, JASON RICHARD
• Application Number:
  US11/012,576
• Publication Number:
  US 20060126857A1
• Time in Patent Office: 636 Days
• Field of Search: 381/59, 381/111, 381/96, 381/58
• US Class Current: 381/59
• CPC Class Codes: H04R 29/003 of the moving-coil type

Abstract

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.

Claims

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.