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, the latch shown in the engaged position; Fig. 7 is a side view of the latch mechanism of Fig. 6 shown in the disengaged position; Fig. 8 is an detail perspective view showing a mounting arrangement for the damping pad of the damping mechanism of the present invention; and Fig. 9 is a side view of a preferred 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 shown in Fig. 3, the hinge mechanism 18 includes a pair of opposed brackets 20,22 coupled to the cover 16, each bracket having a notch 24,26. The hinge mechanism 18 also includes an arm assembly 28 that has a pair of opposed arms 30,32, with each arm having an opening 34,36. The arm assembly 28 has a set of downwardly- extending barbed arms 38 which couple the arm assembly to the body 12 (see Fig. 2). A pivot rod 40 is received through the notches 24,26 in the brackets 20,22 and the holes 34,36 in the arms 30,32 to rotatably couple the cover 16 to the body 12. The hinge mechanism 18 may include a torsion spring 42 mounted about the pivot rod 40 which engages the cover 16 to bias the cover in its open position. Of course, various hinges may be used to couple the cover 16 to the body 12, and the hinge mechanism 18 shown herein is illustrative of only one of many types of hinges that may be used without departing from the scope of the present invention.

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 the access cover 16.

A wide variety of shapes, materials and mounting orientations may be used for 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.

What is claimed is: