Abstract:
A safety ring binder mechanism helps prevent finger pinching by requiring simultaneous opposite movement of sliding actuators at both ends of the mechanism in order to open and close the rings. When the actuators are outermost, dimples on the actuators press the blades of the device against the housing, holding the rings open. When the actuators are pushed in, inclined tongues cam the ends of the blades downward, forcing the rings to close and holding them in a closed position.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates to a ring binder mechanism for securing loose-leaf papers. 
   A typical ring binder mechanism has a sheet metal housing which is longitudinally stiff, but laterally flexible, and contains a pair of blades which are hinged along mating edges. Each blade supports a number of ring halves. The blades have a combined width slightly greater than the width of the housing, so that they toggle between two extreme positions, in one of which the tips of the ring halves meet, forming closed rings, and in another of which the ring halves are open, allowing one to insert or remove loose-leaf papers. 
   As ring binder users know, the rings can pinch a finger painfully when they snap shut. Prior constructions do not keep one from accidentally getting a finger between the ring ends when closing the ring binder mechanism. 
   SUMMARY OF THE INVENTION 
   An object of the invention is to prevent people from pinching their fingers between the rings when closing a ring binder mechanism. A related goal is to provide a construction which requires one to use two hands, away from the ring ends, both to close and to open the rings. 
   Another object of the invention is to prevent people from opening or closing the ring binder mechanism by manipulating the rings directly, that is, to force the user to use two sliding actuators at the ends of the ring binder mechanism to close and open the rings. 
   These and other objects are attained by a safety ring binder mechanism having sliding actuators, as described below. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings, 
       FIG. 1  is an isometric view, from above of a safety ring binder mechanism having two sliding actuators; 
       FIG. 2  is an isometric view of the binder mechanism from below; 
       FIG. 3  is a detailed view of one of the sliding actuators; 
       FIG. 4  is an isometric view of the binder mechanism, with the housing removed to show the underlying detail, in the rings-closed configuration; 
       FIG. 5  is an isometric view of the binder mechanism, with the housing removed to show the underlying detail, in the rings-open configuration; and 
       FIG. 6  is a sectional view, on a transverse plane, showing the interaction between the sliding actuators and the blades when the rings are open. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   A ring binder mechanism embodying the invention, illustrated in  FIGS. 1 and 2 , includes a metal housing  10  which supports opposed sliding actuators  12 ,  14  at either end. Rivets  16 ,  18 , whose upper ends are secured in holes in the housing, extend downward, for connecting the housing to the spine of a loose leaf ring binder. The rings  20 ,  21 ,  22  each comprises two half-rings which are secured to the respective blades  24 ,  26 , by crimping, swaging or staking the lower ends  28  of the rings, where they protrude through holes in the blades. 
   In  FIG. 2 , one can see the two blades  24 ,  26 , their inner edges abutting, and being retained in alignment by alternating tab-like deformations  30  formed along the inner edges. In  FIGS. 1 ,  2  and  4 , the rings are closed, the inner edges of the blades being below an imaginary plane containing the outer edges of the blades. When the rings are opened (FIGS.  5  and  6 ), the inner edges move above that plane. The extreme of upward movement is determined by small dimples  32  ( FIG. 1 ) on the top of the housing, against which the inner edges of the blades come to rest. 
   The rings are open and closed by moving the sliding actuators  12 ,  14  at both ends of the ring binder mechanism simultaneously, in opposite directions. To open the ring binder mechanism, the sliding actuators are pulled away from one another; to close it, they are pushed toward one another. It does not work, as will be described below, to move just one sliding actuator at a time, so both hands must be involved at once, which keeps them away from the ring tips. 
   Each sliding actuator  12 ,  14  includes a generally L-shaped member ( FIG. 3 ) having a long horizontal leg  42  and a short vertical leg  44 . A plastic handle  46  is molded around the vertical leg. The horizontal leg has a slight positive dihedral angle defining two wings  48 , 50 ; this construction contributes to the bending stiffness of the leg. Near the free end  52 , there is a large dimple  54  projecting upward from the leg. The dimple  54  presses upward on the bottoms of the blades  24 ,  26  when the sliding actuator is pulled out, as illustrated in  FIGS. 5 and 6 . When the sliding actuator is pushed in (FIG.  4 ), the dimple rests, disengaged, in an almond-shaped opening  55  formed by opposed cutouts  56  on the inner edges of the blades. 
   The wings of the sliding actuator are at times flush against the blades; the narrow slots  58  in the sliding actuator are provided to clear the lower ends  28  of the rings. A rivet  16  or  18  passes through the larger slot  60 . 
   The pentagonal aperture  62 , seen in  FIGS. 2 and 3 , is created when a tongue  64  is punched upward from the lower leg. The tongue extends, stepwise, obliquely upward from the end  66  which remains connected to the lower leg. The top of the tip  68  of the tongue has about the same elevation as the inside surface of the housing, and is received within a slightly raised region  70  at the end of the housing. 
   The lower leg of each actuator is retained within the housing, below the blades, when the device is assembled. The housing is deformed by indentations  72  ( FIGS. 2 and 6 ) which extend lengthwise along each side of the housing in the region of the sliding actuators. The indentations increase the interior height of the housing at its edges sufficiently to accept both the sliding actuator and the blades, so that the sliding actuator can freely reciprocate within the housing. The stroke of the sliding actuator is determined by the length of the slot  60  and the outer diameter of the rivets. When the sliding actuator is in its outermost position, as mentioned above, the dimple  54  presses the blades upward against the housing (FIGS.  5  and  6 ), locking the rings open, and prevents them from being closed manually. When the sliding actuators are pushed in, the dimples disengage the blades as they become aligned with the opening  55 , allowing the rings to close (FIG.  4 ). Simultaneously, the tongues  64  engage the blades  24 ,  26  from above, forcing them to the rings-closed position. The tongues thus function as sliding cams which bear against the inner end corners of the blades and push them downward during closing. 
   It may be appreciated that the rings cannot be closed when either dimple  54  is not within the corresponding opening  55 , so it is not sufficient to push in just one sliding actuator to close the ring binder mechanism. Both must be moved. 
   Similarly, because the tongues indirectly hold the rings closed when the sliding actuators are in (by pressing down on the ends of the blades), it does not do to pull out just one sliding actuator when trying to open the ring binder mechanism: both must be pulled. Therefore, one cannot easily get a finger in a position when it might be pinched, when opening or closing the ring binder mechanism. 
   Since the invention is subject to modifications and variations, it is intended that the foregoing description and the accompanying drawings shall be interpreted as only illustrative of the invention defined by the following claims.