Abstract:
An active noise cancellation system is provided in a head support to cancel noise for a supine user, lying on a bed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present case is the utility conversion of U.S. Provisional Patent Application 61/696,484 filed Sep. 4, 2012, entitled “Active Quiet Pillow” which incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Active Noise Cancellation (ANC) is an acoustic technology that relies on the measurement of extraneous noise and creating a control signal that can cancel the extraneous noise at a particular point in space. These systems though complex are well understood and widely applied. 
         [0003]    For example U.S. patent application Ser. No. 11/952,250 filed Dec. 7, 2008 discloses an electronic pillow that can abate the sounds of snoring. See also U.S. Pat. No. 5,884,996 that integrates ANC into the headboard of a bed. 
         [0004]    In spite of theses developments there is a continuing need to develop devices with larger “sweet spots” for noise cancelation and improved comfort for users. 
       SUMMARY OF THE INVENTION 
       [0005]    In contrast to prior art designs the device of the invention incorporates both active ANC technology as well as passive sound absorption technologies that are applied to a unique “pillow” geometry. Together all of these disparate elements provide wide band noise suppression and cancelation in a portable unit that can be used in either a hospital or home setting. In general the active quiet pillow device will be used with a conventional bed. The user will lie down supine with the users head cradled in the active quiet pillow device. The device incorporates a soft comfortable foam liner covering the interior surfaces. The device contains several active speaker components under the foam that cooperate with an ANC controller to cancel sound at the users ears. The soft cushion material or “foam” supports the head with comfort and acts to attenuate noise as well. The active components are largely placed under the foam in experimentally determined locations that greatly improve the observed performance in contrast to prior devices. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0006]    Throughout the figures of the drawing, like reference numerals indicate identical structure wherein: 
           [0007]      FIG. 1  is a schematic cross-section of the device, and 
           [0008]      FIG. 2  is a perspective view of the device. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0009]      FIG. 1  shows a cross section on the device in schematic form. The active quiet pillow device  10  cradles the user&#39;s  28  head, while the user  28  is supine on bed  40 . The exterior of the device is generally rectilinear comprising exterior side-wall  20  and exterior side-wall  22 . Theses exterior side-walls are coupled to the exterior bottom wall  11  and the generally U-shaped top surface  17 , as well as the exterior back surface  15 . Together these surfaces serve to define an acoustic chamber having an acoustic volume  44  with outside dimensions of height (H) length (L) and width (W). The head rests on foam surfaces generally designated  24  in the figures, and the height dimension is tall enough to place the ears at a mid-side-wall position. However this position must be balanced with a height (H) that is not so tall as to put the side-walls into the peripheral vision of the user&#39;s eyes. It has been determined that this consideration improves comfort for many users. 
         [0010]    The interior volume is large enough to carry a subwoofer active speaker  42  which is coupled to the ANC controller  32  output directly below the user&#39;s head, and two mid-range active speakers  34  and  46  located proximate the user&#39;s ears on the two inclined side walls. Typically the ANC control module  32  and associated wiring will be positioned within this volume  44  as well however remote location is acceptable, for example the controller may be attached to the bed  40 . It is anticipated that the controller and its associated audio amplifiers will be line powered and a cord and switch will be found on the exterior surface, although not all of the wiring is shown to simplify the figures and improve clarity. 
         [0011]      FIG. 2  shows a perspective view of the visible surfaces of the active quiet pillow device  10 . By way of overview the exterior surfaces are generally rectilinear and the interior surfaces have two tapered sidewalls  19  and  21  facing the users ears. A back wall is near the crown of the user&#39;s head. The interior surfaces are covered with a soft conformal acoustic foam. The height “H” of the sidewalls is sufficient to cover the level of the ears but not so high as to be visible in the visual field of the user. Experiment has suggested that this feature reduces the sensation of claustrophobia that may otherwise be present in some users. The space between the exterior walls namely; first exterior side-wall  20 , second exterior side-wall  22 , exterior bottom wall  11 , exterior back wall  15  and the interior walls, namely first interior side-wall  19 , second interior side-wall  21 , interior bottom wall  12 , interior back wall  14  together define an enclosed acoustic volume generally designated  44 . 
         [0012]    An active subwoofer speaker  42  is positioned proximate the back of the user&#39;s head in the lower bottom wall of the acoustic volume. Separate first and second mid range speakers typified by speaker  34  and  46  are located in the side walls proximate the user&#39;s ears. One or more error microphones  30  maybe mounted proximate the ears as well as typified in the figure by microphone  30  and  31 . The ANC controller  32  may be mounted in either the acoustic volume or exterior of the acoustic volume. A remote reference microphone designated  26  in the figure is coupled to he ANC controller. Wires  48  connect the ANC controller  32  to the various speakers and microphones. In use the ambient noise is sampled and the speakers driven to cancel the ambient sound as measured near the user&#39;s ears by microphones  30  and  31 . In use the ANC system is used actively suppress noise have a characteristic frequency below about 400 Hz. Attenuation above 400 Hz is managed with the acoustic foam liner and interior geometry of the device. Together this active and passive system provides a quiet environment at the ears of the user.