Patent Publication Number: US-2006006307-A1

Title: System and method for attenuating mechanical vibrations

Description:
PRIOR APPLICATION  
      This application claims the benefit of U.S. Provisional Application Ser. No. 60/585,573, filed Jul. 7, 2004 entitled “SYSTEM AND METHOD FOR ATTENUATING MECHANICAL VIBRATIONS”. 
    
    
     FIELD OF THE INVENTION  
      This invention relates to systems for attenuating mechanical vibrations.  
     BACKGROUND OF THE INVENTION  
      Many types of devices produce or affected by unwanted mechanical vibrations. For example, audio/video equipment can vibrate when sound is produced. These vibrations distort the acoustical output, resulting in inferior sound reproduction. These vibrations may also transmit to the floor supporting the device. In a situation where tenants are nearby, the unwanted noise is a nuisance. This is particularly the case in apartment buildings when audio/video equipment is operated at times likely to inconvenience other tenants.  
      Unwanted vibrations can arise in a device from a number of sources. The preeminent source is the device itself. Loudspeakers cause components coupled thereto, such as speaker cabinets, to vibrate. Also, the sound produced by loudspeakers when incident on other components of an audio/video system cause these components to vibrate. Other sources of vibration are external to the audio/video system and arise from other electrical devices, such as appliances like refrigerators, furnaces and air conditioners. Likewise, vehicular traffic (e.g., automobiles, trains, airplanes) can cause unwanted vibrations. All these sources of external vibrations can rattle audio/video equipment producing deleterious effects in sound reproduction. These unwanted vibrations are often at resonant frequencies that can lead to large amplitude vibrations.  
      Unwanted vibrations can distort sound in a number of ways. Low-level detail may be blurred or concealed. Bass, which is typically difficult to reproduce, is compromised. Fidelity and musicality can be adulterated. Oftentimes, manufacturers spend a lot of time an energy producing equipment that has superior musical output without giving much thought to how unwanted vibrations can reduce the quality of the sound experience. It is not uncommon for high-end equipment to cost tens of thousands of dollars without being able to perform to its potential because of extraneous mechanical vibrations.  
      While audio/video equipment has been emphasized above, there are many other types of devices where unwanted mechanical vibrations are a problem. A few of these include, operating theaters, where vibrations can have serious consequences when performing microsurgery, and laser systems where the precise application of a laser to a particular area is of paramount importance.  
      Therefore, a system that can reduce or eliminate unwanted mechanical vibrations by effectively dampening these vibrations would be most welcome.  
     SUMMARY OF THE INVENTION  
      Described herein is a system for reducing mechanical vibrations in a device. The system includes a base for resting on a surface, such as a floor, and a platform for resting the device thereon. Compressible spokes connect the platform to the base. Mechanical vibrations of the device are attenuated by the base, platform and spokes when the device is resting on the platform. The spokes are composed of a dampening material such as polyurethane. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       FIG. 1  shows a block diagram of an attenuating system  10  for attenuating mechanical vibrations in a device  12 . In a typical application, the device  12  includes audio/video equipment, such as CD players, DVD players, pre-amplifiers and amplifiers. By reducing vibrations, the system  10  helps improve the sound quality and fidelity of the audio/video equipment. In another application, the device can be an operating table at a hospital.  
      The system  10  includes a base  14 , a platform  16  and compressible spokes  18  connecting the platform  16  to the base  14 .  
      The base  14  rests on a surface, such as a floor, desk or cabinet. The device  12  rests on the platform  16 . Compressible spokes  18  connect the platform  16  to the base  14 . Mechanical vibrations of the device  12  are attenuated as vibrational energy travels from the device  12 , to the platform  16 , to the spokes  18  and then finally to the base  14 . Most of the vibrational energy is absorbed before reaching the base  14 . Consequently, the surface on which the base  14  rests, such as a floor, does not vibrate, which is particularly helpful where such vibrations would inconvenience others, such as would be the case in a high-rise apartment building.  
      The system  10  also finds use in many other areas where a reduction of mechanical vibrations is desired, such as in operating theaters, where the elimination of vibrations are important for surgery, especially microsurgery, and in research environments where precise measurements require the diminution of unwanted vibrations.  
      The compressible spokes  18  may be composed of self-skinned polyurethane molded foam. In such case, the whole system  10  may be conveniently composed of polyurethane using a single mold. Other cured or porous materials may also be used.  
      To support a device  12 , any number of systems  10  can be used. Typically, four systems  10  can be placed at the corners of a box-shaped device  12 . However, more or less than four systems  10  may be placed under the device  12 , as appropriate.  
       FIGS. 2A and 2B  show in side and plan views, respectively, an attenuating system  30  for attenuating mechanical vibrations in a device  32 , such as audio/video equipment, consistent with the principles of the present invention. The system  30  includes a ring-shaped base  34  of diameter d 1 , and a disk-shaped platform  36  of diameter d 2 &lt;d 1 , the platform  36  being co-axial with the base  34  and disposed above the base  34 . Compressible spokes  38  connect the platform  36  to the base  34 .  
      The ring-shaped base  34  rests on a surface, such as a floor, desk or cabinet. The device  32  rests on the disk-shaped platform  36 . The compressible nature of the spokes  38  help to reduce mechanical vibrations of the device  32 , as vibrational energy travels from the disk-shaped platform  36  to the ring-shaped base  34  via the spokes  38 .  
      The compressible spokes  38  may be composed of self-skinned polyurethane molded foam. In such case, the whole system  30  may be conveniently composed of polyurethane using a single mold. If desired, the external polyurethane surface of the system  30  may be painted. Various colours that would be attractive alongside the audio/video equipment can be used.  
      The number of compressible spokes  38  is usually three or more. The precise number can depend on the weight of the device  32 . In particular, as the weight increases, a system  30  with more spokes  38  can be used to prevent the platform  36  from otherwise collapsing. In addition, the density of the polyurethane comprising the components of the system  30  can vary according to the weight of the device  32 , the lower the density of the polyurethane the smaller the weight of the device  32 .  
       FIGS. 3A and 3B  show in side and plan views, respectively, an attenuating system  50  for attenuating mechanical vibrations of a device  52 . The system  50  includes a disk-shaped base  54  of diameter d 1 , and a ring-shaped platform  56  of diameter d 2 &gt;d 1 , the platform  56  being co-axial with the base  54  and disposed above the base  54 . Compressible spokes  58  connect the platform  56  to the base  54 .  
      As will immediately be recognized, system  50  is the same as system  30  but inverted so that the device  52  rests on the wider ring-shaped platform  56  instead of the narrower disk shaped base  54 . The disk-shaped base  54  rests on a surface, such as a floor, desk or cabinet. The compressible nature of the spokes  58  help to reduce mechanical vibrations of the device  52 , as vibrational energy travels from the ring-shaped platform  56  to the disk-shaped base via the spokes  58 . As described above, the system  50  may be composed of polyurethane and derived from a single mold.  
       FIG. 4  shows a stack system  70  comprised of the systems  30  and  50  of  FIGS. 2 and 3 . Such a stack system  70  is formed by stacking systems  30  and  50  so that the disk-shaped platform  36  abuts the disk-shaped base  54 . The ring-shaped base  34  rests on a surface, such as a floor, and the device  52  rests on the ring-shaped platform  56 . The stack system  70  can be used to attenuate particularly large mechanical vibrations, where system  30  or system  50  alone might not be adequate. Another application of the stack formation arises when the height of device  32  resting thereon needs to be raised. It should be appreciated that a plurality of pairs of systems  30  and  50  may be stacked to form a stack system  70  that is arbitrarily tall.  
       FIG. 4  shows the system  50  of  FIG. 3  stacked on top of the system  30  of  FIG. 2 . It should be understood that in another embodiment, system  30  may be stacked on top of system  50 . In such case, the disc-shaped base rests on a surface, such as a floor or cabinet surface, while the device  32  rests on the disc-shaped platform  36 .  
       FIG. 5A  shows an attenuating system  90  exemplifying another embodiment for attenuating mechanical vibrations of a device  92 . The system  90  includes a three-walled, box-shaped base  94 , a rectangular-shaped platform  96  and compressible spokes  98  connecting the platform  96  to the base  94 . The spokes  98  are individually removably attached to the platform  96  and to the base  94 .  
      The base  94  rests on a surface, such as a floor, desk or cabinet. The device  92  rests on the platform  96 . Compressible spokes  98  connect the platform  96  to the base  94 . Mechanical vibrations of the device  92  are attenuated as vibrational energy travels from the device  92 , to the platform  96 , to the spokes  98  and then finally to the base  94 , with most of the vibrational energy being absorbed before reaching the base  94 .  
       FIG. 5B  shows an exploded view of a portion of  FIG. 5A  with the platform  96  omitted, and  FIG. 5C  shows an exploded view of the underside  100  of the platform  96  of  FIG. 5A  with the base  94  omitted. In  FIG. 5B , three base female receptors  102 ,  104  and  106  are shown on the base  94 . In  FIG. 5C , three complementary platform female receptors  108 ,  110  and  112  are shown on the underside  100  of the platform  96 .  
      Each of the female receptors  102 ,  104  and  106  can receive a single compressible spoke  98 . One compressible spoke  98  is shown, one portion  114  of which is manually inserted into the base female receptor  104 . An opposite portion  116  is inserted into the complementary platform female receptor  110  on the underside  100  of the platform  96 .  
      Although  FIGS. 5B and 5B  each only display three female receptors  102 ,  104  and  106 , and  108 ,  110  and  112 , it should be understood that more receptors are present around the periphery of both the base  94  and platform  96 . For a particular application, however, not all receptors need contain a spoke  98 . The number of spokes  98  present in the system  90  depends on the amplitude of the mechanical vibrations that are to be attenuated and on the weight of the device, the greater the amplitude or weight, the larger the number of spokes  98  that can be used. By adding enough spokes  98 , collapse of the platform  96  due a heavy device  92  resting thereon is avoided. The spokes  98  are individually removable by hand and fit into the female receptors  102 ,  104  and  106 , and  108 ,  110  and  112 . Because the spokes  98  are compressible, they may be made to fit snugly, perhaps by having to squeeze the spokes  98  before insertion into the receptors. Each spoke  98  is bone-shaped with two “knobs” on either side. The knobs prevent the spokes from sliding out of the receptors  102 ,  104  and  106 , and  108 ,  110  and  112  under the weight of the device  92 . That is, although the spokes  98  are designed to stretch when a device  92  is placed on the platform, the knobs do not stretch to the point where the spoke  98  can slip out of the receptor. It should be understood that the density and the size of the spokes  98  (and the size of the corresponding receptors) may vary. For example, a heavier device load might require the use of denser or larger receptors.  
      The embodiment that is the system  90  of  FIG. 5  may be modified in a number of ways. First, the rear vertical wall of the base  94  and the rear edge of the platform  96  may also include receptors. By inserting spokes  98  therein, the base  94  and the platform  96  may be further connected at the rear. In addition, the base  94  may be constructed to include a front fourth wall, whose height may be different than the heights of the other three walls of the base  94 . For example, the front fourth wall may be shorter than the other three walls with the top of the front wall substantially flush with the platform  96 . Making the front fourth wall shorter in this manner allows devices to be easily inserted into a stack arrangement of systems  90  (see  FIG. 6 , described below).  
      It should also be understood that the “linear density” of spokes  98  (i.e., the number of spokes per unit length) and/or receptors need not be uniform along the various walls of the base  94 . If the system  90  is designed for a device that has a non-uniform weight distribution, then more receptors and spokes can be added to whichever side bears the greater amount of weight of the device.  
      The base  94  and platform  96  can be composed of any one of number of materials including wood, plywood, Masonite™, acrylic and medium density fiberboard (MDF). The spokes  98  can be composed of any compressible material, such as polyurethane.  
       FIG. 6  shows a system  130  for attenuating mechanical vibrations that is comprised of a plurality of the attenuating systems  90  stacked one on top of each other. The back wall of the base  94  can have a gap at the bottom to allow electrical wires from the device  92  to exit the back. The system can accommodate several devices  92 ,  132  and  134 . For example, the devices  92 ,  132  and  134  can be components of an audio/video system, such as a CD player, amplifier and DVD player.  
       FIGS. 7A and 7B  show a plan view and cross section of a system  150  for attenuating mechanical vibrations of a device  152 , especially designed for devices such as speaker systems but which may also be used for other devices that produce unwanted vibrations. The system  150  includes a compressible component  154  and a dense component  156 . The compressible component  154  can be composed of polyurethane, for example. The dense component  156  has a covered portion  158  and an uncovered portion  160 . The covered portion  158  is covered and in contact with the compressible component  154 .  
      The dense component  156  need not be monolithic, but can instead be made from a number of subparts. In one embodiment, for example, a center core of the dense component  156  may be hollow. Later in the manufacturing process, a complementary piece of dense component can be removably or, preferably, permanently inserted into the hollow center core.  
      The device  152  rests on a part of the uncovered portion  160 , vibrational energy from the device  152  being attenuated by the compressible component  154 .  
      In the embodiment of the system  150  shown in  FIG. 7 , the system  150  is disk-shaped. The disk has an external surface the largest fraction of which is composed of the compressible component  154 . A smaller fraction of the external surface, near the center of the disk on either side thereof, is composed of the dense component  156 . At the center of the disk, on either side, is a notch  162  that can be used with speaker systems, and other audio/video equipment, having spikes  163  at the base. Each spike  163  of the speaker system can be inserted into a notch  162 .  
      Because the dense component  156  is designed to sustain the pressure below the notch  162  due to the weight of the device  152 , it is desirable that the dense component  156  be composed of a dense material, such as acrylic, nylon, plastic, polyvinylchloride or any other material that can be injected and which dries to form a dense solid.  
      A component of an audio/video system typically contains four spikes  163  at the base, and under each such spike  163 , a system  150  can be placed to attenuate vibrations.  
      Vibrational energy is received from the device  152  by the dense component  156 . In turn, the dense component  156  transmits the vibrational energy to the compressible component  154 , where the vibrations are dampened.  
      In other applications, the system  150  can be used for devices having no spikes. For example, spikeless speakers can rest directly on the compressible component  154 . Likewise, the legs of an operating table can rest directly on the compressible component to reduce vibrations of the table during an operation.  
      It should be understood that various modifications could be made to the embodiments described and illustrated herein, without departing from the present invention. For example, although emphasis has been placed on a system for attenuating mechanical vibrations in audio/video equipment, the present system and method can be also applied to other devices where unwanted vibrations exist, such as medical equipment, and manufacturing equipment. The scope of the invention is defined in the appended claims.