Abstract:
A damping mechanism for use with a housing having a body and a cover pivotably attached to the body, the cover being movable between an open position and a closed position. The damping mechanism includes a body engagement surface located on the body and a cover engagement surface located on the cover. One of the body engagement surface or the cover engagement surface includes a generally planar damping pad and the other of the body engagement surface or the cover engagement surface includes a cam having a generally curved cam surface. The cam surface is shaped and positioned to engage the damping pad such that the damping pad and the cam cooperate to damp the movement of the cover when the cover pivots between the open and closed positions.

Description:
BACKGROUND OF INVENTION 
     The present invention is directed to damping mechanisms, and more particularly, to damping mechanisms for use with hinged covers of housings and other enclosures. 
     Electronic devices, such as printers, copiers, facsimile machines, scanners, CD players and the like typically include a body that provides structural integrity to the device. In order to provide access to the internal components of the device, the body typically includes an access opening that is protected by a movable cover. The cover is movable between an open position and a closed position such that the internal components of the device can be accessed through the access opening. The cover may be biased in either the open or closed position, and a detent mechanism may be used to maintain the cover in its non-biased position. Various mechanisms, such as springs, air/hydraulic piston assemblies, or gravity may be used to bias the cover in the open or closed positions. However, the biasing mechanisms may not provide for a smooth, controlled opening or closing motion of the access cover. Accordingly, there is a need for a damping mechanism that damps the motion of the cover of an electronic device. 
     SUMMARY OF THE INVENTION 
     The present invention is a damping mechanism which can be used to damp the movement of a cover of a housing, such an electronic device. The damping mechanism includes a cam having a generally curved cam surface that is shaped to engage a generally planar damping surface. The damping pad and cam cooperate to slow the opening or closing motion of the cover. 
     In a preferred embodiment, the invention is a damping mechanism for use with a housing having a body and a cover pivotably attached to the body, the cover being movable between an open position and a closed position. The damping mechanism includes a body engagement surface located on the body and a cover engagement surface located on the cover. One of the body engagement surface or the cover engagement surface includes a generally planar damping pad and the other of the body engagement surface or the cover engagement surface includes a cam having a generally curved cam surface. The cam surface is shaped and positioned to engage the damping pad such that the damping pad and the cam cooperate to damp the movement of the cover when the cover pivots between the open and closed positions. 
     Accordingly, it is an object of the present invention to provide a damping mechanism for a cover of an electronic device that is robust and durable. Other objects and advantages of the present invention will be apparent from the following description and the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an upper perspective view of a printer including one embodiment of the damping mechanism of the present invention, with the cover in the closed position; 
     FIG. 2 is an upper perspective view of the printer of FIG. 1, with the cover in the open position; 
     FIG. 3 is a lower perspective view of the damping mechanism of the printer of FIGS. 1 and 2; 
     FIG. 4 is an upper perspective view of the cover of the printer of FIG. 1; 
     FIG. 5 is an upper perspective view of the cover of FIG. 4, with the outer shell removed; 
     FIG. 6 is a side view the latch mechanism of the printer of FIG. 1, with the outer shell removed, the latch shown in the engaged position; 
     FIG. 7 is a side view of the latch mechanism of the printer of FIG. 1 with the outer shell removed and the latch shown in the disengaged position; 
     FIG. 8 is an detail perspective view showing an alternative mounting arrangement for the damping pad of the damping mechanism of the present invention; and 
     FIG. 9 is a side view of an embodiment of the damping mechanism of the present invention. 
    
    
     DETAILED DESCRIPTION 
     As shown in FIGS. 1 and 2, the damping mechanism  11  of the present invention may be used in a business machine, such as a printer or housing  10  having a body  12 . The body  12  includes an access opening  14  that is selectively covered by a cover  16 . The cover  16  is pivotably coupled to the body  12  by a hinge mechanism  18 . In this manner, the cover  16  is moveable between a closed position (FIG. 1) and an open position FIG.  2 ). 
     As best shown in FIG. 3, the cover  16  includes a cover engagement surface  70 . In the illustrated embodiment the cover engagement surface  70  is a cam  72  having a cam surface  74  that is generally curved in side view. The cam  72  can be made from a variety of materials, preferably plastics, such as high impact polystyrene. In the illustrated embodiment the cam  72  is integral with the cover  16 , and is generally shaped as a portion of a circle in top view. The body  12  includes a body engagement surface  76  that is shaped and located to engage the cover engagement surface  70 . Although FIG. 3 does not illustrate the body engagement surface  76  as being coupled to the body  12 , various mechanisms (such as adhesives, clamps, fasteners, interference fits, etc.) known to those of ordinary skill may be used, although a preferred manner for mounting the body engagement surface  76  to the body is illustrated and discussed below. In the illustrated embodiment the body engagement surface  76  is generally planar damping pad  78 , although other shapes of damping pads may be used. For example, the damping pad may be curved to match the curvature of the cover engagement surface. The damping pad  78  may be made from a variety of materials, but is preferably made of a resilient compressible material which provide high friction forces when the damping pad  78  engages the cam  72 . The damping pad  78  is preferably made of a thermal plastic elastomer, such as SANTOPRENE 101-55. 
     As shown in FIG. 4, the cover  16  includes an outer shell  46  and an inner shell  48 . A latch assembly  50  (FIG. 5) is located between the outer shell  46  and the inner shell  48 . The latch assembly  50  includes a handle  52 , an arm  54  and a catch  56 . The arm  54  is pivotably mounted to the inner shell  48  at pivot point  49 , and the catch  56  is aligned with an opening  58  in the inner shell. The upper end of the arm  54  is coupled to a latch spring  60  that extends between the inner shell  48  and the arm  54 . As shown in FIG. 4, the outer shell  46  of the cover  16  substantially covers the latch assembly  50 , and includes a indentation  63  to receive the handle  52 . 
     In order to lock the cover  16  in its closed position, the catch  56  extends through the opening  58  in the inner shell  48  and is received in a notch  64  in the front cover  66  of the body  12  (FIG.  6 ). When the catch  56  is received in the notch  64  (i.e., the latch assembly  50  is in its engaged position), the catch engages the top surface of notch  64  to maintain the cover  16  in its closed position. The latch assembly  50  is biased into its engaged position by the latch spring  60 . When it is desired to move the cover  16  to its open position, the handle  52  is pulled to move the latch assembly  50  to its release position (shown in FIG.  7 ), compressing the latch spring  60 . When the catch  56  is rotated clear of the notch  64 , the cover  16  moves to its open position and as biased by the torsion spring  42 . 
     As best shown in FIG. 3, the cover  16  includes a cover engagement surface  70 . In the illustrated embodiment the cover engagement surface  70  is a cam  72  having a cam surface  74  that is generally curved in side view. The cam  72  can be made from a variety of materials, preferably plastics, such as high impact polystyrene. In the illustrated embodiment the cam  72  is integral with the cover  16 , and is generally shaped as a portion of a circle in top view. The body  12  includes a body engagement surface  76  that is shaped and located to engage the cover engagement surface  70 . Although FIG. 3 does not illustrate the body engagement surface  76  as being coupled to the body  12 , various mechanisms (such as adhesives, clamps, fasteners, interference fits, etc.) known to those of ordinary skill may be used, although a preferred manner for mounting the body engagement surface  76  to the body is illustrated and discussed below. In the illustrated embodiment the body engagement surface  76  is generally planar damping pad  78 , although other shapes of damping pads may be used. For example, the damping pad may be curved to match the curvature of the cover engagement surface. The damping pad  78  may be made from a variety of materials, but is preferably made of a resilient compressible material which provide high friction forces when the damping pad  78  engages the cam  72 . The damping pad  78  is preferably made of a thermal plastic elastomer, such as Santoprene 101-55. 
     Once the latch assembly  50  is moved to its disengaged position, the cover  16  moves from its closed to its open position, as biased by the spring  42 . As the cover  16  moves from its closed to its open position, the cam surface  74  engages the damping pad  78 , and the frictional forces between the cam surface  74  and the pad  78  slow the opening movement of the cover  16 . As shown in FIGS. 8-9, the damping pad  78  is preferably mounted onto a leaf spring  81  formed by cantilevered arm  84 . In this manner, the leaf spring  81  biases the damping pad  78  against the cam  72  when the cam surface  74  first engages the damping pad  78 . Thus, when the cam surface  74  first engages the damping pad, there is a relatively high amount of friction between the cam surface and the damping pad  78 . However, as the cam  72  and damping pad  78  “compresses” the damping pad spring  81  (i.e., moves the cantilevered arm  84  radially outwardly), frictional forces between the cam  72  and the damping pad  78  are decreased. Thus, the damping forces of the damping mechanism  11  are highest when the cam  72  first engages the damping pad  78 . This is desirable because the torsion spring  42  exert its highest opening forces during the initial opening movement of the cover  16 , and therefore the strongest damping of the damping mechanism  11  corresponds to the strongest forces exerted by the torsion spring  42 . After the damping pad spring  81  is “compressed,” the friction forces between the damping pad  78  and the cam surface  74  result in a smooth, controlled opening motion of he access cover  16 . 
     A wide variety of shapes, materials and mounting orientations may be used or the cam  72  and the damping pad  78  without departing from the scope of the invention. Furthermore, a variety of biasing mechanisms, such as a standard coil spring, may be used in place of the leaf spring  81  to bias the damping pad  78  against the cam surface. Further alternately, the cam surface  74  may be spring biased against the damping pad  78 . In yet another alternate embodiment, the damping pad  72  is located on the cover  16  and the cam  72  is located on the body  12 . In this case the cam  72  is stationary as the damping pad  72  moves with the cover  16  during its opening or closing motion. 
     When the cover  16  is moved from its open position to the closed position, the cam surface  74  and damping pad  78  may frictionally engage each other to oppose the closing motion of the cover  16 . However, the frictional forces generated between the cam surface  74  and the damping pad  78  are relatively low compared to the biasing force of the torsion spring that must also be overcome to close the cover. 
     In a preferred embodiment, the damping mechanism  11  selectively damps the opening or closing motion of the cover  16 . As shown in FIG. 9, the cam  72  may include a protrusion portion  80  that extends radially outwardly from a recessed portion  82  of the cam. In this case, the cam surface  74  is located on the outer surface of the protrusion portion  80 . For example, the cam  72  may be generally shaped as a section of a circle in top view (such as a section extending for about 110° of a full circle). The protrusion portion  80  may protrude radially outwardly for about 30° of the full 110° of the cam  72 , and be located about 10° from a lower edge  83  of the cam. Thus, for example, if the cover  16  moves about 110° when it moves from its closed position to its open position, the cam surface  74  engages the damping pad  78  for about 30° of the total 110° of travel. In the illustrated embodiment, the first 10° of rotational travel of the cam  72  (indicated by section A of FIG. 9) is undamped, the next 30° of travel (indicated by section B) is damped by the cooperation between the damping pad  78  and the cam surface  74 , and the remaining 70° of travel (indicated by section C) is undamped. 
     The initial, undamped 10° of opening motion allows the cover  16  to quickly “spring” open to ensure that the catch  56  quickly clears the notch  64  when the latch mechanism  50  is moved to its disengaged position. The next 30° of opening motion of the cover  16  is damped, to provide a smooth, controlled opening motion of the cover  16 . Of course, as noted above, relatively high damping forces are applied when the cam  72  first engages the damping pad  78 . Finally, the remaining 60° of travel of the cover  16  is undamped because the force exerted by the torsion spring  42  at this portion of travel of the cover is relatively weak. In this manner, the cam  72  shown in FIG. 9 is shaped to provide different levels of damping as the cover  16  moves from the open position and the closed position to provide a smooth opening motion. Of course, the size and shape of the cam  72  or damping pad  78  may be varied to provide for a variety of damping profiles, as desired. 
     Having described the invention in detail and by reference to the preferred embodiments, it will be apparent that modifications and variations thereof are possible without departing from the scope of the invention.