Active noise control with planar transducers
Active noise control (ANC), including active and adaptive noise cancellation (ANC) with non-voice-coil transducers having highly linear transfer functions, such as planar transducers, planar magnetic transducers, electro-static transducers, and piezo-electric transducers. This active and adaptive noise cancellation (ANC) may be used with: planar transducer headphones and earphones; open-backed and closed-back headphones and earphones; in-ear earphones, and phase plugs.
1. An audio device comprising:
an active noise control (ANC) system including an input for receiving an audio source signal, at least one microphone input for receiving microphone signals, and an output for providing a corrected audio signal;
at least one microphone connected to the at least one microphone input; and
a transducer including an input for receiving the corrected audio signal from the ANC system and an output for providing output sound waves, such that the transducer is a non-voice-coil transducer, and wherein the transducer further comprises
a diaphragm including an electro-mechanical system for converting the input into the output for providing sound waves, and
a mechano-electrical system coupled to the diaphragm having a mechano-electrical output such that motion of sound waves impacting the diaphragm generates a proportionate mechano-electrical output signal, wherein the mechano-electrical system acts as the at least one microphone connected to the at least one microphone input.
2. The audio device of claim 1 wherein the transducer is a non-cone transducer.
3. The audio device of claim 1 wherein the transducer is a planar transducer.
4. The audio device of claim 1 wherein the transducer is a planar magnetic transducer.
5. The audio device of claim 1 wherein the diaphragm comprises a single diaphragm having a trace pattern with two separate circuits, the diaphragm being disposed in a magnetic field, where the two separate circuits comprise
an input circuit disposed on the diaphragm being operative for an input signal from an audio amplifier such that the amplifier current flows through the input circuit trace pattern in the magnetic field which causes the diaphragm to vibrate at audio frequencies in accordance with the input signal, and
an output circuit for an output signal generated from the vibrations of the output traces disposed on the diaphragm in the same magnetic field.
6. The audio device of claim 1 wherein the audio device is a hybrid feedforward-feedback audio device, such that
the at least one microphone is a feed forward microphone, and
the at least one microphone input is a feed forward microphone input.
7. The audio device of claim 1 wherein the active noise control system includes an adaptive noise cancellation system.
8. The audio device of claim 1 wherein the active noise control system includes an analog or digital control system.
9. An audio device comprising:
an active noise control (ANC) system including an input for receiving an audio source signal, at least one microphone input for receiving microphone signals, and an output for providing a corrected audio signal;
at least one microphone connected to the at least one microphone input;
a transducer including an input for receiving the corrected audio signal from the ANC system and an output for providing output sound waves,
such that the transducer is a non-voice-coil transducer; and
a housing having:
a proximal acoustic opening configured for positioning proximal to an ear, and
a distal surface located distally from the proximal acoustic opening,
wherein the non-voice-coil transducer is disposed in the housing such that the non-voice-coil transducer divides the housing into
a proximal cavity between the non-voice-coil transducer and the proximal acoustic opening, and
a distal cavity between the non-voice-coil transducer and the distal surface, and
at least one microphone disposed in the housing.
10. The audio device of claim 9 such that the proximal cavity includes at least one feedback microphone.
11. The audio device of claim 9 such that the distal cavity includes at least one feed-forward microphone.
12. The audio device of claim 9 such that the distal surface is configured with at least two acoustically transparent openings.
13. The audio device of claim 9 such that the distal cavity contains acoustically absorbent material.
14. The audio device of claim 9 such that the non-voice-coil transducer comprises a planar magnetic transducer.
15. The audio device of claim 9 such that the non-voice-coil transducer comprises an electro-static transducer.
16. The audio device of claim 9 such that the non-voice-coil transducer comprises a piezo-electric transducer.
17. An audio device comprising:
an active noise control (ANC) system including an input for receiving an audio source signal, at least one microphone input for receiving microphone signals, and an output for providing a corrected audio signal;
at least one microphone connected to the at least one microphone input,
a transducer including an input for receiving the corrected audio signal from the ANC system and an output for providing output sound waves,
such that the transducer is a planar transducer;
a housing having
a proximal acoustic opening configured for positioning in an ear canal, and
a distal surface located distally from the proximal acoustic opening,
the planar transducer disposed in the housing such that the planar transducer divides the housing into
a proximal cavity between the planar transducer and the proximal acoustic opening, and
a distal cavity between the planar transducer and the distal surface; and
at least one microphone disposed in the housing.
18. The audio device of claim 17 such that the proximal cavity includes at least one feedback microphone.
19. The audio device of claim 17 such that the proximal cavity includes a phase plug.
20. The audio device of claim 19 such that the phase plug includes the at least one feedback microphone.
21. The audio device of claim 20 such that the at least one feedback microphone included in the phase plug has an internal microphone opening leading toward the proximal acoustic opening.
22. The audio device of claim 21 such that the internal microphone opening acts as a waveguide toward the proximal acoustic opening.
23. The audio device of claim 17 such that the distal cavity includes at least one feed-forward microphone.
24. The audio device of claim 17 such that the distal surface is configured with at least one acoustically transparent opening.
25. The audio device of claim 17 such that the planar transducer includes a planar magnetic transducer.
26. The audio device of claim 17 such that the planar transducer includes an electro-static transducer.
27. The audio device of claim 17 such that the planar transducer includes a piezo-electric transducer.