Passive acoustical radiating
An audio device has passive radiators that are driven by acoustic drivers. The passive radiators are arranged so that the net mechanical vibration is minimized.
1. An acoustic device, comprising,
an acoustic enclosure bounded by a three dimensional bounding figure said enclosure having walls defining an enclosure interior volume,
an acoustic driver having a first surface and a second surface, first and second surfaces radiating along a first axis,
wherein said acoustic driver is mounted in said acoustic enclosure so that said first surface faces said enclosure interior volume,
a cavity in said acoustic enclosure lying substantially within said bounding figure and comprising a cavity opening to an external environment,
a first passive radiator having a first surface and a second surface and an intended direction of motion along a second axis, mounted in said acoustic enclosure so that said first passive radiator first surface faces said cavity and said passive radiator second surface faces said enclosure interior volume and,
a second passive radiator having a first surface and a second surface and an intended direction of motion along a third axis, said second passive radiator mounted so that second passive radiator first surface faces said cavity and said second passive radiator second surface faces said enclosure interior volume,
wherein said acoustic enclosure is constructed and arranged so that all acoustic paths between said acoustic driver first surface and said cavity includes at least one of first passive radiator and said second passive radiator.
2. An acoustic device in accordance with claim 1 ,
wherein said second passive radiator is further mounted so that said first passive radiator intended direction of motion and said second passive radiator intended direction of motion are substantially parallel.
3. An acoustic device in accordance with claim 2 constructed and arranged so that operation of said acoustic driver causes vibration of said first passive radiator and said second passive radiator,
said vibration of said first passive radiator and said second passive radiator radiating acoustic energy in phase into said cavity,
said vibration resulting in inertial forces of said first passive radiator and said second passive radiator,
wherein said first passive radiator and said second passive radiator are positioned so that a vector sum of said inertial forces of the first passive radiator and said second passive radiator is less than either of said inertial forces of said first passive radiator and said second passive radiator.
4. An acoustic device in accordance with claim 3 wherein said first and second passive radiators are constructed and arranged so that said vibration of said first passive radiator and said vibration of said second passive radiator are mechanically out of phase.
5. An acoustic device in accordance with claim 2 ,
said acoustic driver having an intended direction of motion wherein said acoustic driver intended direction of motion is substantially parallel with at least one of said first passive radiator intended direction of motion and said second passive radiator intended direction of motion.
6. An acoustic device in accordance with claim 1 and further comprising an acoustic driver mounted in said acoustic enclosure so that said acoustic driver radiates acoustic energy into said interior volume,
a plurality of passive radiators acoustically coupling said interior volume and said cavity,
and wherein all acoustic paths from said acoustic driver through said interior volume to said cavity include at least one of said plurality of passive radiators.
7. An acoustic device comprising,
an acoustic enclosure bounded by a three dimensional bounding figure,
the enclosure having walls defining an enclosure interior volume,
a cavity in the acoustic enclosure lying substantially within the bounding figure and separated from the interior volume, and comprising a cavity opening to an external environment,
an acoustical driver mounted in the acoustic enclosure,
the acoustic driver having a vibratile diaphragm for vibrating along a first axis to radiate acoustic energy,
the diaphragm having a first radiating surface facing the exterior of the acoustic enclosure for radiating acoustic energy to the exterior and a second radiating surface constructed and arranged so that substantially all of the second radiating surface faces the interior volume for radiating acoustic energy into the acoustic volume,
a first passive radiator acoustically coupling the interior volume and the cavity, the first passive radiator comprising a first vibratile diaphragm, and
a second passive radiator acoustically coupling the interior volume and the cavity, the first passive radiator comprising a second vibratile diaphragm,
the first and second vibratile diaphragms constructed and arranged to vibrate along a second axis responsive to the acoustic energy radiated into the interior volume to radiate acoustic energy into the cavity.
8. An acoustic device in accordance with claim 7 wherein the first axis and the second axis are parallel.
9. An acoustic device in accordance with claim 2 , wherein said acoustic device is constructed and arranged so that said first passive radiator and said second passive radiator vibrate mechanically out of phase responsive to said acoustic energy radiated into said interior volume by said acoustic driver.
10. An acoustic device in accordance with claim 9 , wherein said second axis and said third axis are coincident.
11. An acoustic device in accordance with claim 10 wherein said coincident second and third axes are parallel with said first axis.
12. An acoustic device in accordance with claim 2 wherein said second axis and said third axis are parallel with said first axis.