Abstract:
The device dampens vibrations between objects, especially for preventing the transfer of vibrations from a primary object subjected to vibrations, to a vibration-sensitive secondary object. The secondary object is non-rigidly supported by a damping body, which has the same or essentially the same size of mass as the secondary object, and which in turn is non-rigidly supported on the primary object.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a device for the damping of vibrations between objects, especially for preventing the transfer of vibrations from a primary object, subjected to vibrations, to a secondary object which is sensitive to vibrations. 
     In, for example, playback apparatus for audio and video discs with optical reading of rotating information-carrying discs and also in analogue record players, the functions of the respective optical laser pickup units, stylus pickups, gear drives and turntable details are extremely sensitive to vibrations from the surroundings. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to suggest an improved device for preventing undesired vibrations being transferred to vibration-sensitive objects, i.e. to damp away or extinguish such vibrations. According to a first aspect of the invention, this function is solved in a device of the type mentioned in the introduction through the secondary vibration-sensitive object being non-rigidly supported by a damping body itself non-rigidly supported on the primary object, the damping body having the same or essentially the same size mass as the secondary object. It has been shown that placing a non-rigidly supported damping body between on the one side a supported object, which is to be protected from vibrations, and on the other side a vibrating object, wherein the mass of the damping body is the same or essentially the same as the mass of the supported object, provides an effective interruption in the transfer of vibrations to the supported object. Through such adjustment of the mass of the damping body to the mass of the supported object, they will dynamically be in an antiphase relationship to each other in such a way that the vibrations from below are extinguished by the damping body so that the supported object is not influenced by the vibrating body below it. 
     This principle for damping away vibrations is also applicable in the opposite case, where the supported object is a producer of vibrations, e.g. a compressor, washing-machine of the like and where the underlayer, e.g. a support or floor, is to be protected against vibrations. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is described in more detail below with reference to a plurality of embodiments in the accompanying drawings, in which: 
     FIG. 1 is a schematic perspective view of a embodiment showing the principle of a device according to the invention; 
     FIGS. 1 a - 1   g  show different types of resilient means between the damping body and the supported object; 
     FIG. 2 shows schematically an application of the invention on a gear drive and laser pickup unit of a CD-player; 
     FIG. 3 shows an embodiment where a complete vibration-sensitive apparatus is enclosed and supported in a casing over a damping arrangement according to the invention; 
     FIG. 4 shows schematically an analogue record player, where the damping arrangement according to the invention is applied on the one hand to the turntable, on the other hand to the stylus pickup supported on the tone arm; 
     FIGS. 5 &amp; 6 show schematically a damping arrangement according to the invention applied to loudspeakers; and 
     FIGS. 7-9 show further application examples of the damping arrangement according to the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows a general example of an embodiment of the vibration-damping device according to the present invention.  10  relates to an object, which is sensitive to vibrations and which it is desired to hold completely free from vibrations which can occur in the underlayer  12  upon which the object  10  is supported. Two parts  14  and  16  between which no vibrations are allowed to occur, are shown symbolically on the object  10 . In order to prevent vibrations in the underlayer  12  being transferred to the object  10 , it is suggested according to the invention that the object be supported non-rigidly on the damping body  18 , which has the same or substantially the same mass as the object  10  and which in its turn is non-rigidly supported on the underlayer  12 . By a suitable selecting and balancing of the resilient elements  20  between the object  10  and the damping body  18 , and the resilient elements  22  between the damping body  18  and the underlayer  12 , it is possible to effectively prevent vibrations being transferred from the underlayer  12  to the object sensitive to vibrations  10 . In this way the damping body  18  will work in an antiphase relationship to the vibrations in the underlayer so that these are damped out or extinguished. 
     FIGS. 1 a - 1   g  show schematically different forms of resilient elements between the damping body  18  and the object  10 , where FIGS. 1 a - 1   c  show resilient elements  20 ,  22  of the helical spring type, which are complemented with damping means  21   a ,  21   b  in FIG. 1 b  resp.  1   c . The resilient elements  20 ,  22  in FIG. 1 d  are formed from solid hourglass-shaped rubber bodies, while those in FIGS. 1 e  and  1   f  are formed of hollow or ring-shaped rubber elements. FIG. 1 g  shows an embodiment where the object  10 , which is to have its vibrations damped, is suspended in the damping body  18  by resilient elements  20  in the shape of oval rubber rings. The damping body  18  in turn is suspended in a carrier  12   a  by means of similar oval rubber rings  22 . Naturally the resilient elements  22 , which support approximately twice as much load as the resilient elements  20 , must be more powerfully dimensioned in order to give similar spring characteristics to the object  10  and the damping body  18 . 
     This vibration-damping principle can be put into practice in many fields. Reference is made below to several conceivable suitable application examples. 
     FIG. 2 shows a CD-player  24  where both a laser pickup arm  26  and a gear drive unit  28  in the player are non-rigidly supported by means of elastic elements  30  resp.  32  on a respective damping body  34 ,  36 , which has the same mass as the arm  26  resp. the unit  28  and in turn is non-rigidly supported in the body or chassis of the CD-player  24  by way of elastic elements  38  resp.  40 . The elastic elements  30 ,  32  and  38 ,  40  suitably comprise elastic rubber elements shaped and adapted to give the supported parts  26 ,  28  the same spring characteristics as their respective damping bodies  34 ,  36 . By means of such a constructive solution, the vibration-sensitive bodies  26 ,  28  of the CD-player  24  can be completely isolated from vibrations of normal range and magnitude coming from below. By analogy with this embodiment the invention can naturally also be adapted to CD-ROM-players. 
     FIG. 3 shows an embodiment where a complete HiFi-apparatus  42 , e.g. a CD-player, is non-rigidly supported on a underlayer surface  44  acting as a damping body, which has the same mass as the apparatus  42  and which in its turn is non-rigidly supported in a casing  46  which surrounds the whole of the apparatus  42 . 
     FIG. 4 shows an analogue record player  48 , in which the present invention has been applied in three different places. Thus, the turntable  50  of the record player  48  is non-rigidly supported by a camping body disc  52  which can rotate together with the turntable  50  and which has the same or essentially the same mass as the turntable including a LP-record lying on it. The damping disc  52  in turn is non-rigidly supported by a drive disc  54  which can produce vibrations. The stylus pickup  55  can also be vibration-insulatingly supported in an analogue manner as well as also the bearing support  55   b  of the tone arm  55   a.    
     FIGS. 5 and 6 show the present invention adapted to loudspeakers where FIG. 5 shows a large multi-way loudspeaker  56 , non-rigidly supported on a, in turn non-rigidly supported, damping body  58  of the same or essentially the same mass as the loudspeaker  56 . FIG. 6 shows separate tweeter, mid-range and woofer units  60 ,  62  resp.  64 , which are non-rigidly supported on respective damping bodies  66 ,  68  and  70  according to the invention. 
     FIG. 7 shows both an instrument  72  with a vibration-insulating damping body  74  according to the invention and a drawingboard top  76  with a similar vibration-damping, elastically supported damping slab  78 . 
     Furthermore, FIG. 8 shows a vibration damper according to the present invention adapted for a laser measuring instrument  80 , which in non-rigidly supported on a stand  82  by means of an intermediate, non-rigidly supported damping body  84  of the same or essentially the same mass as the measuring instrument  80 . 
     The present invention is also adaptable in the cases where it is desirable to prevent vibrations from a supported object being transferred to an underlying support or floor. FIG. 9 shows an example where a vibration-producing compressor  86  is non-rigidly supported on a damping body  88  by way of elastic elements  90 , which damping body  88  has the same or essentially the same mass as the compressor  86  and is non-rigidly supported on an underlayer or support  92  via elastic elements  94 . 
     The vibration damping arrangement according to the present invention is fundamentally applicable in many other areas of use within the scope of the following claims.