Speaker unit with active leak compensation

• US 20040184623A1
• Filed: 03/05/2004
• Published: 09/23/2004
• Est. Priority Date: 03/07/2003
• Status: Abandoned Application

• Current Assignee: Sonion Horsens A/S
• Original Assignee: Sonion Horsens A/S
• Inventors: Andersen, Morten Kjeldsen, Johannsen, Leif
• Application Number:
  US10/793,010
• Publication Number:
  US 20040184623A1
• Time in Patent Office: Days
• US Class Current: 381/117
• CPC Class Codes: H04R 2499/11 Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's
• CPC Class Codes: H04R 3/002 Damping circuit arrangements for transducers, e.g. motional feedback circuits

Abstract

The present invention relates to an electro dynamic speaker unit comprising an electro dynamic motor adapted for receiving a first electrical signal and to drive a diaphragm in accordance with the received first electrical signal. The speaker unit further comprises sensing means adapted for generating a second electrical signal in accordance with a movement of the diaphragm, and determining means adapted for receiving the first and the second electrical signals so as to determine an acoustical load of the speaker unit from the first and the second electrical signals. The determining means further generates a third electrical signal in accordance with the determined acoustical load of the speaker unit. The present invention further relates to a method for active leak compensation of an electro dynamic speaker unit.

Claims

1. An electro dynamic speaker unit comprising

an electro dynamic motor adapted for receiving a first electrical signal and to drive a diaphragm in accordance with the received first electrical signal, the diaphragm being adapted to emit an acoustical output signal,

sensing means adapted for generating a second electrical signal in accordance with a movement of the diaphragm, and

determining means adapted for receiving the first and the second electrical signals so as to determine an acoustical load of the speaker unit from the first and the second electrical signals, and to generate a third electrical signal in accordance with the determined acoustical load of the speaker unit.

2. An electro dynamic speaker unit according to claim 1, further comprising compensation means adapted to

receive the first and the third electrical signal,

modify the received first electrical signal in accordance with the received third electrical signal so as to compensate for the determined acoustical load of the speaker unit, and

provide the modified first electrical signal to the electro dynamic motor in order to emit a modified acoustical output signal.

3. An electro dynamic speaker unit according to claim 1, wherein the determining means is adapted to detect movements of the diaphragm in at least a first and a second frequency band, the first frequency band being lower than the second frequency band, the determining means further being adapted to detect corresponding levels of the first electrical signal within the first and within the second frequency band.

4. An electro dynamic speaker unit according to claim 3, wherein the determining means is adapted to determine the acoustical load of the speaker unit from

a difference in sensed diaphragm movements at least at one frequency within the first and the second frequency band, and

a difference in the level of the first electrical signal at least at one frequency within the first and second frequency band.

5. An electro dynamic speaker unit according to claim 4, wherein the first frequency band has an upper frequency limit below or equal to 1 kHz, and wherein the second frequency band has a lower frequency limit higher than 1 kHz.

6. An electro dynamic speaker unit according to claim 3, wherein the first and the second frequency bands have bandwidths of less than ⅓

of an octave relative to a centre frequency of the first and second frequency bands respectively.

7. An electro dynamic speaker unit according to claim 1, wherein the sensing means comprises a capacitive sensor where a first plate of the capacitive sensor is formed by an electrically conductive front plate of a housing of the speaker unit, and wherein a second plate of the capacitive sensor is formed by a conductive layer on the diaphragm.

8. An electro dynamic speaker unit according to claim 1, wherein the sensing means comprises a microphone.

9. An electro dynamic speaker unit according to claim 8, wherein the speaker unit further comprises a housing, wherein the microphone is positioned so as to sense the sound pressure within the housing.

10. An electro dynamic speaker unit according to claim 8, wherein the microphone is positioned so as to sense the sound pressure on a front side of the diaphragm.

11. An electro dynamic speaker unit according to claim 8, wherein the microphone is attached to the diaphragm.

12. An electro dynamic speaker unit according to claim 8, wherein the microphone is a silicon based microphone.

13. An electro dynamic speaker unit according to claim 1, wherein the determining means is implemented in an ASIC.

14. An electro dynamic speaker unit according to claim 1, wherein the compensation means is implemented in an ASIC.

15. An electro dynamic speaker unit according to claims 1, wherein the determining means and the compensation means are implemented in a single ASIC.

16. An electro dynamic speaker unit according to claim 12, wherein the silicon microphone is integrated into the single ASIC.

17. An electro dynamic speaker unit according to claim 13, wherein the ASIC is attached to the diaphragm.

18. An electro dynamic speaker unit according to claim 17, wherein the ASIC is attached to a back side of the diaphragm.

19. An electro dynamic speaker unit according to claim 1, wherein the sensing means comprises a coil for detecting changes in a magnetic field generated by the electro dynamic motor driving the diaphragm.

31. A mobile phone comprising an electro dynamic speaker unit according to claim 1.

32. A telephone handset comprising an electro dynamic speaker unit according to claim 1.

33. A telephone headset comprising an electro dynamic speaker unit according to claim 1.

20. A method for active leak compensation of an electro dynamic speaker unit, the method comprising the steps of:

driving a diaphragm by means of an electro dynamic motor adapted to receive a first electrical signal, the diaphragm being adapted to emit an acoustical signal,

sensing a movement of the diaphragm of the speaker unit, and generating a second electrical signal in accordance with the sensed movement of the diaphragm,

determining an acoustical load of the speaker unit from the first and the second electrical signals, and

generating a third electrical signal in accordance with the determined acoustical load of the speaker unit.

21. A method according to claim 20, further comprising the steps of:

modifying the first electrical signal in accordance with the received third electrical signal so as to compensate for the determined acoustical load of the speaker unit, and

providing the modified first electrical signal to the electro dynamic motor so as to emit a modified acoustical output signal.

22. A method according to claim 20, wherein the determination of the acoustical load comprises detection of movements of the diaphragm in at least a first and a second frequency band, the first frequency band being lower than the second frequency band, and detection of corresponding levels of the first electrical signal within the first and within the second frequency band.

23. A method according to claim 22, wherein the determination of the acoustical load of the speaker unit comprises the steps of

determining a difference in sensed diaphragm movements within the first and within the second frequency band, and

determining a difference in the levels of the first electrical signal within the first and within the second frequency band.

24. A method according to claim 23, wherein the first frequency band has an upper frequency limit below or equal to 1 kHz, and the second frequency band has a lower frequency limit higher than 1 kHz.

25. A method according to claim 22, wherein the first and the second frequency bands have bandwidths of less than ⅓

of an octave relative to a centre frequency of the first and second frequency bands respectively.

26. A method according to claim 20, wherein the sensing comprises capacitive sensing, wherein a first plate of a capacitive sensor is formed by an electrically conducting front plate of a housing of the speaker unit, and wherein a second plate of the capacitive sensor is formed by a conductive layer on the diaphragm.

27. A method according to claim 20, wherein a sound pressure corresponding to movements of the diaphragm is measured using a microphone.

28. A method according to claim 27, wherein the sound pressure is measured within a housing of the speaker unit.

29. A method according to claim 27, wherein the sound pressure is measured in front of the diaphragm.

30. A method according to claim 20, wherein the sensing of diaphragm movements is provided using a coil adapted to detect changes in a magnetic field generated by the electro dynamic motor driving the diaphragm.

34. The use of active leak compensation according to claim 20 in a mobile phone.

35. The use of active leak compensation according to claim 20 in a telephone handset.

36. The use of active leak compensation according to claim 20 in a telephone headset.