Vehicle accessory microphone

• US 20020110256A1
• Filed: 02/14/2002
• Published: 08/15/2002
• Est. Priority Date: 02/14/2001
• Status: Active Grant

• Current Assignee: Gentex Corporation
• Original Assignee: Gentex Corporation
• Inventors: Watson, Alan R., Bryson, Michael A., Spence, William R.
• Granted Patent: US 6,882,734 B2
• Time in Patent Office: Days
• US Class Current: 381/389
• CPC Class Codes: B60R 1/12 Mirror assemblies combined with other articles, e.g. clocks
• CPC Class Codes: B60R 11/0247 for microphones or earphones
• CPC Class Codes: B60R 11/0252 for personal computers, e.g. laptops, notebooks
• CPC Class Codes: B60R 2001/1284 with communication systems other than radio-receivers, e.g. keyless entry systems, navigation systems; with anti-collision systems
• CPC Class Codes: B60R 2011/0033 Rear-view mirrors
• CPC Class Codes: H04R 1/083 Special constructions of mouthpieces
• CPC Class Codes: H04R 1/38 in which sound waves act upon both sides of a diaphragm and incorporating acoustic phase-shifting means, e.g. pressure-gradient microphone
• CPC Class Codes: H04R 1/406 microphones
• CPC Class Codes: H04R 2410/07 Mechanical or electrical reduction of wind noise generated by wind passing a microphone
• CPC Class Codes: H04R 2499/13 Acoustic transducers and sound field adaptation in vehicles
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407
• CPC Class Codes: H04R 3/04 for correcting frequency response

Abstract

A microphone assembly includes one or more transducers positioned in one or more housings. A processing circuit is coupled to the transducer for outputting an electrical signal such that the microphone in combination with the processing circuit very effectively cancels noise. The microphone assembly can be employed in a vehicle accessory.

Claims

1. A microphone system comprising:

a microphone assembly comprising a first transducer generating a first audio signal and a second transducer generating a second audio signal;

a remote processing circuit located remote from said microphone assembly; and

a microphone interface circuit electrically coupled between said transducers and said remote processing circuit, said microphone interface circuit comprising;

a first electrical signal path extending between said first transducer and said remote processing circuit, and

a second electrical signal path extending between said second transducer and said remote processing circuit, said second electrical signal path including a phase inverter circuit provided proximate said second transducer for inverting the phase of the second audio signal,

wherein said remote processing circuit is configured to recognize that the phase of the second audio signal has been inverted and process the second audio signal accordingly, said remote processing circuit will also recognize common signals on both said first and second electrical signal paths as being line-induced noise.

2. The microphone system of claim 1, wherein said remote processing circuit recognizes common signals as being line-induced noise when such common signals are in-phase with one another.

3. The microphone system of claim 1, wherein said remote processing circuit re-inverts the phase of the second audio signal and recognizes common signals as being line-induced noise when such common signals are out of phase with one another.

4. The microphone system of claim 1, wherein said remote processing circuit is a digital processing circuit.

5. The microphone system of claim 1, wherein the audio signals generated by said transducers are high-gain audio signals.

6. A vehicle accessory comprising:

a housing for attaching to a vehicle;

a microphone assembly carried by said housing and comprising a first transducer generating a first audio signal and a second transducer generating a second audio signal;

a microphone interface circuit electrically coupled between said transducers and a remote processing circuit located remote from said microphone assembly, said microphone interface circuit comprising;

a first electrical signal path extending between said first transducer and the remote processing circuit, and

a second electrical signal path extending between said second transducer and the remote processing circuit, said second electrical signal path including a phase inverter circuit provided proximate said second transducer for inverting the phase of the second audio signal.

7. The vehicle accessory of claim 6, wherein said housing is a mirror housing.

8. The vehicle accessory of claim 6, wherein the audio signals generated by said transducers are high-gain audio signals.

9. The vehicle accessory of claim 6, wherein said microphone assembly further comprises a microphone housing having a plurality of ports with windscreens provided across said ports, said first and second transducers positioned in said microphone housing, the front of said second transducer facing a different direction from the front of said first transducer, wherein said ports, windscreens and transducers are configured such that said microphone assembly exhibits a first polar pattern with null aimed at a driver of the vehicle, and a second polar pattern with a null aimed at a front passenger area of the vehicle.

10. The vehicle accessory of claim 6 and further comprising a high frequency boost circuit coupled to said transducers for receiving the audio signal and for boosting the frequency response at high frequencies to compensate for the effect of the vehicle on the frequency response of the microphone assembly.

11. A vehicle accessory comprising:

a housing for attaching to a vehicle;

a microphone assembly carried by said housing and comprising at least one transducer, the microphone assembly generating an audio signal;

a microphone interface circuit electrically coupled between said transducer and a remote processing circuit located remote from said microphone assembly, said microphone interface circuit comprising;

a first electrical signal path extending between said transducer and the remote processing circuit,

an impedance matching circuit for providing an electrical connection to ground having an impedance matching that of said transducer, and

a second electrical signal path extending between said impedance matching circuit and the remote processing circuit adjacent said first electrical signal path, the second electrical signal path providing the remote processing circuit with a reference of the line-induced noise present on said first signal path such that the remote processing circuit may cancel the line-induced noise from the first electrical signal path by subtracting the noise signal received from the second electrical signal path from the signal received from the first electrical signal path.

12. The vehicle accessory of claim 11, wherein the audio signal generated by said microphone assembly is a high-gain audio signal.

13. The vehicle accessory of claim 11, wherein said microphone assembly further comprises:

a microphone housing having a plurality of ports with windscreens provided across said ports;

a first transducer positioned in said microphone housing and generating a first audio signal; and

a second transducer positioned in said microphone housing and generating a second audio signal, the front of said second transducer facing a different direction from the front of said first transducer,

wherein said ports, windscreens and transducers are configured such that said microphone assembly exhibits a first polar pattern with null aimed at a driver of the vehicle, and a second polar pattern with a null aimed at a front passenger area of the vehicle.

14. The vehicle accessory of claim 11 and further comprising a high frequency boost circuit coupled to said transducer for receiving the audio signal and for boosting the frequency response at high frequencies to compensate for the effect of the vehicle on the frequency response of the microphone assembly.

16. The vehicle accessory of claim 15, wherein said first and second transducers are positioned facing one another with their central axes being co-linear.

17. The vehicle accessory of claim 16, wherein said ports are configured nonsymmetrically.

18. The vehicle accessory of claim 17, wherein said windscreen has an acoustic resistivity of at least about 8 acoustic ohms per cm².

19. The vehicle accessory of claim 16, wherein said windscreen has an acoustic resistivity of at least about 8 acoustic ohms per cm².

20. The vehicle accessory of claim 15, wherein said ports are configured nonsymmetrically.

21. The vehicle accessory of claim 15, wherein said windscreen has an acoustic resistivity of at least about 8 acoustic ohms per cm².

22. The vehicle accessory of claim 15, wherein said first transducer is positioned with its rear surface aimed at the driver and the second transducer is positioned with its rear surface aimed at the front passenger area.

23. The vehicle accessory of claim 15, wherein said second transducer is positioned with its front surface aimed at the driver.

24. The vehicle accessory of claim 15, wherein said microphone housing is a separate housing from said accessory housing and is secured to an exterior of said accessory housing.

25. The vehicle accessory of claim 15 and further comprising a microphone interface circuit electrically coupled between said transducers and a remote processing circuit located remote from said microphone assembly, said microphone interface circuit comprising:

a first electrical signal path extending between said first transducer and the remote processing circuit, and

a second electrical signal path extending between said second transducer and the remote processing circuit, said second electrical signal path including a phase inverter circuit provided proximate said second transducer for inverting the phase of the second audio signal.

26. The vehicle accessory of claim 15 and further comprising a high frequency boost circuit coupled to said transducers for receiving the audio signal and for boosting the frequency response at high frequencies to compensate for the effect of the vehicle on the frequency response of the microphone assembly.

28. The vehicle accessory of claim 27, wherein said high frequency boost circuit boosts the frequency response such that the frequency response curve associated with the microphone assembly independent of the effect of the vehicle is substantially not flat.

29. The vehicle accessory of claim 27, wherein said high frequency boost circuit boosts the frequency response between about 3.5 and 5 kHz.

30. The vehicle accessory of claim 27, wherein the accessory housing is a rearview mirror assembly housing.

15. A vehicle accessory comprising:

an accessory housing for attaching to a vehicle; and

a microphone assembly carried by said accessory housing and comprising;

a microphone housing having a plurality of ports with windscreens provided across said ports;

a first transducer positioned in said microphone housing and generating a first audio signal; and

a second transducer positioned in said microphone housing and generating a second audio signal, the front of said second transducer facing a different direction from the front of said first transducer,

wherein said ports, windscreens and transducers are configured such that said microphone assembly exhibits a first polar pattern with null aimed at a driver of the vehicle, and a second polar pattern with a null aimed at a front passenger area of the vehicle.

27. A vehicle accessory comprising:

an accessory housing for attaching to a vehicle;

a microphone assembly carried by said accessory housing and including at least one transducer supplying an audio signal; and

a high frequency boost circuit coupled to said transducer for receiving the audio signal and for boosting the frequency response at high frequencies to compensate for the effect of the vehicle on the frequency response of the microphone assembly.

31. A vehicle accessory comprising:

an accessory housing for attaching to a vehicle;

a first microphone assembly supported by said accessory housing; and

a second microphone assembly supported by said accessory housing at a location laterally spaced from said first microphone assembly,

wherein said first and second microphone assemblies have a “

D”

of at least about 3.5 mm.

32. The vehicle accessory of claim 31, wherein said microphone assemblies have a “

D”

of about 10 mm.

33. The vehicle accessory of claim 31, wherein said microphone assemblies are spaced apart from one another by at least about 5 cm.

34. The vehicle accessory of claim 31, wherein said microphone assemblies are spaced apart from one another by at least about 18 cm.

35. The vehicle accessory of claim 31, wherein said first and second microphone assemblies each include a front port and a rear port, the front and rear ports being sealed by a high resistance windscreen.

36. The vehicle accessory of claim 35, wherein each microphone assembly includes a narrow channel extending between said front and rear ports and includes a transducer disposed in said channel with its front surface facing said front port and its rear surface facing said rear port.

37. The vehicle accessory of claim 36, wherein a rear cavity formed in said channel between the rear surface of said transducer and said high resistance windscreen at said rear port has a greater volume than a front cavity formed in said channel between the front surface of said transducer and said high resistance windscreen at said front port.

38. The vehicle accessory of claim 35, wherein said front port is flared.

39. The vehicle accessory of claim 31, wherein each of said first and second microphone assemblies include a transducer, the central axes of the transducers in said first and second microphone assemblies being angled with respect to one another.

40. The vehicle accessory of claim 39, wherein the central axes of the transducers in said first and second microphone assemblies are aimed at an angle upward relative to the position of a driver of the vehicle.

41. The vehicle accessory of claim 31, wherein each of said first and second microphone assemblies include an omni-directional transducer.

42. The vehicle accessory of claim 31, wherein the accessory housing is a rearview mirror assembly housing including a mirror having a front surface, and wherein said microphone assemblies are disposed at opposite ends of said mirror assembly housing.

43. The vehicle accessory of claim 42, wherein said microphone assemblies are disposed in the rear surface of said mirror housing.

44. The vehicle accessory of claim 43, wherein said first and second microphone assemblies each include a front port and a rear port, the front and rear ports being sealed by a high resistance windscreen, each microphone assembly includes a narrow channel extending between said front and rear ports and includes a transducer disposed in said channel with its front surface facing said front port and its rear surface facing said rear port.

45. The vehicle accessory of claim 44, wherein said channels are disposed at an angle relative to the front surface of said mirror.

46. The vehicle accessory of claim 45, wherein said front ports of said first and second microphone assemblies are disposed closer to said mirror than said rear ports.

47. The vehicle accessory of claim 45, wherein said channels are disposed at an angle relative to one another.

49. The vehicle accessory of claim 48, wherein said cloth is made of a polyester material.

50. The vehicle accessory of claim 48, wherein said housing includes a rigid deflector disposed proximate said microphone assembly to deflect airflow away from said microphone assembly, wherein said cloth deflector extends from said rigid deflector.

51. The vehicle accessory of claim 48, wherein said cloth deflector has an open area of about 35%.

48. A vehicle accessory comprising:

a housing for attaching to a vehicle;

a microphone assembly carried on said housing and including a windscreen; and

a cloth deflector disposed on said housing proximate said microphone assembly to deflect airflow away from said microphone assembly.

52. A vehicle accessory comprising:

a housing for attaching to a vehicle;

a first transducer supported by said housing;

a second transducer supported by said housing and laterally spaced from said first transducer; and

a separator disposed between said first and second transducers to physically deflect airflow coming from the side of said first transducer away from said second transducer and to physically deflect airflow coming from the side of said second transducer away from said first transducer.

53. The vehicle accessory of claim 52, wherein said housing is a rearview mirror assembly housing.

54. The vehicle accessory of claim 52, wherein said transducers are positioned with their central axes at an angle to one another.

55. The vehicle accessory of claim 52, and further comprising:

a first housing having at least one acoustic port, said first transducer disposed in said first housing and acoustically coupled to said acoustic port of said first housing;

a first windscreen disposed across said acoustic port of said first housing;

a second housing having at least one acoustic port, said second transducer disposed in said second housing and acoustically coupled to said acoustic port of said second housing; and

a second windscreen disposed across said acoustic port of said second housing.

57. The rearview mirror assembly of claim 56, wherein said second transducer exhibits an omni-directional polar sensitivity pattern.

58. The rearview mirror assembly of claim 57, wherein said fourth transducer exhibits a cardioid polar sensitivity pattern.

59. The rearview mirror assembly of claim 57, wherein said first transducer exhibits a cardioid polar sensitivity pattern.

56. A rearview mirror assembly for a vehicle comprising:

a mirror housing for attaching to the vehicle;

a mirror disposed in said mirror housing and having a front surface;

a first microphone housing supported by said mirror housing;

first and second transducers disposed in said first microphone housing;

a second microphone housing supported by said mirror housing; and

third and fourth transducers disposed in said second microphone housing,

wherein said first microphone housing is disposed closer to the front surface of said mirror than said second microphone housing, said second transducer and said fourth transducer being provided to respectively alter the polar pattern associated with said first and second microphone housings to compensate for frequency discrepancies caused by the proximity of said first microphone housing to the front surface of said mirror.