Abstract:
A ring binder mechanism that retains loose-leaf pages and has ring members that readily lock together, preventing accidental loss of pages. The mechanism comprises a housing that supports two hinge plates for pivoting motion, bringing the ring members to either an open position or a closed position. The mechanism further comprises a control structure, which includes an actuator moveable relative to the housing for controlling pivoting movement of the hinge plates. The actuator is connected to a travel bar that is moveable by the actuator into position for blocking pivoting motion of the hinge plates when the ring members are closed. The connection of the travel bar to the actuator permits the actuator to move in a range without actuating corresponding movement of the travel bar.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a Divisional of U.S. patent application Ser. No. 10/870,801 filed Jun. 17, 2004, which is a Continuation-In-Part of U.S. patent application Ser. No. 10/323,052, filed Dec. 18, 2002 (now U.S. Pat. No. 7,296,946), and a non-provisional application of U.S. patent application Ser. No. 60/553,154, filed Mar. 15, 2004, the entire texts of which are hereby incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   This invention relates to a ring binder mechanism for retaining loose-leaf pages, and in particular to an improved mechanism for opening and closing ring members and for readily and securely locking ring members together. 
   As is known in the art, a typical ring binder mechanism retains loose-leaf pages, such as hole-punched papers, in a file or notebook. It generally features multiple rings each including two half ring members capable of selectively opening to add or remove pages, or selectively closing to retain pages and allow them to move along the ring members. The ring members mount on two adjacent hinge plates that join together about a pivot axis for pivoting movement within an elongated housing. The housing loosely holds the hinge plates so they may pivot relative to the housing. The undeformed housing is slightly narrower than the joined hinge plates when the hinge plates are in a coplanar position (180°). So as the hinge plates pivot through this position, they deform the resilient housing and cause a spring force in the housing urging the hinge plates to pivot away from the coplanar position either opening or closing the ring members. Thus, when the ring members are closed the spring force resists hinge plate movement and clamps the ring members together. Similarly, when the ring members are open, the spring force holds them apart. An operator may typically overcome this force by manually pulling the ring members apart or pushing them together. In addition, in some mechanisms the operator may move a lever located at one or both ends of the mechanism for moving the hinge plates through the coplanar position to open or close the ring members (in addition to manually pulling the ring members apart or pushing them together). 
   One drawback to these typical ring binder mechanisms is that when the ring members close, the housing&#39;s spring force snaps them together rapidly and with a force that might cause fingers to be pinched between the ring members. The substantial spring force required to keep the ring members closed also makes pivoting the hinge plates through the coplanar position (180°) difficult so that it is hard to both open and close the ring members. Another drawback is that when the ring members are closed, they do not positively lock together. So if the mechanism is accidentally dropped, the ring members may unintentionally open. Still another drawback is that over time the housing may begin to permanently deform, reducing its ability to uniformly clamp the ring members together and possibly causing uneven movements or gaps between closed ring members. 
   To address these concerns, some ring binder mechanisms include a control slide attached directly to the lever. These control slides have inclined cam surfaces that project through openings in the hinge plates for rigidly controlling the hinge plates&#39; pivoting motion both when opening and closing the ring members. Examples of these types of mechanisms are shown in U.S. Pat. Nos. 4,566,817, 4,571,108, and 6,276,862 and in U.K. Pat. No. 2,292,343. Some of these cam surfaces have a stop for blocking the hinge plates&#39; pivoting motion when the ring members are closed and for locking the closed ring members together. An operator may open or close these mechanisms by either manipulating the ring members or moving the lever. But to lock the mechanisms, the operator must move the lever and the control slide to position the stops to block the hinge plates from pivoting. 
   These mechanisms still have several drawbacks. When the ring members close, the housing&#39;s spring force may still snap them together. The spring force may also still make both opening and closing the ring members difficult. In addition, when the mechanisms close they do not readily lock. Instead, an operator must directly move the lever and control slide to lock the mechanisms. Furthermore, the control slides in these mechanisms, specifically their inclined cam surfaces and stops, are complexly shaped and can be difficult and time consuming to fabricate. Moreover, since the control slides directly bias the hinge plates, they are usually relatively wide and may need to be constructed of a large gauge metal to withstand forces associated with repeated use (i.e., repeatedly driving the hinge plates to pivot). Therefore, the openings in the hinge plates receiving these control slides may also be relatively wide, possibly weakening the hinge plates so that they too must be made of a large gauge metal. This may make mass production more costly. 
   Consequently, there is a need for a ring binder mechanism that readily locks when ring members close for retaining loose-leaf pages, but has ring members that easily open and close and do not snap together. The present invention is directed to such a ring binder mechanism. 
   SUMMARY OF THE INVENTION 
   In one aspect of the present invention, a ring binder mechanism generally comprises a housing and hinge plates supported by the housing for pivoting motion about a pivot axis relative to the housing. The mechanism has rings for holding loose-leaf pages. Each ring includes a first ring member mounted on a first hinge plate and moveable with the pivoting motion of the first hinge plate. Each ring further includes a second ring member. The first ring member is movable relative to the second ring member so that in a closed position the two ring members form a substantially continuous, closed loop for allowing loose-leaf pages retained by the rings to be moved along the rings from one ring member to the other. In an open position the two ring members form a discontinuous, open loop for adding or removing loose-leaf pages from the rings. An actuator is pivotally mounted on the housing and movable relative to the housing for controlling the pivoting motion of the hinge plates opening and closing the ring members. A travel bar has a connection to the actuator for being moved by the actuator into position for blocking the pivoting motion of the hinge plates when the ring members are closed. The connection of the travel bar to the actuator permits the actuator to move in a range without actuating corresponding movement of the travel bar. 
   Other objects and features of the present invention will be in part apparent and in part pointed out hereinafter. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective of a notebook incorporating a ring binder mechanism of the present invention according to a first embodiment; 
       FIG. 2A  is a perspective of the ring binder mechanism at a closed and locked position; 
       FIG. 2B  is a section taken on line  2 B- 2 B of  FIG. 2A ; 
       FIG. 3A  is a perspective similar to  FIG. 2A  with the mechanism at an open position; 
       FIG. 3B  is a section taken on line  3 B- 3 B of  FIG. 3A ; 
       FIG. 4  is an exploded perspective of the mechanism; 
       FIG. 5  is a perspective similar to  FIG. 2A  with a portion of a housing, a travel bar, and ring members broken away; 
       FIG. 6  is a bottom perspective of the travel bar of the first embodiment; 
       FIG. 7  is the perspective of  FIG. 5  with the mechanism at an intermediate transitional position between the open position and the closed and locked position; 
       FIG. 8  is the perspective of  FIG. 5  with the mechanism at the open position; 
       FIG. 9  is a bottom perspective of an alternative version of the travel bar with a portion of the travel bar and a portion of a locking element thereof broken away; 
       FIG. 10A  is a bottom perspective of a second embodiment of a ring binder mechanism of the present invention at a closed position; 
       FIG. 10B  is a section taken on line  10 B- 10 B of  FIG. 10A  and inverted to an upright orientation; 
       FIG. 11A  is the perspective of  FIG. 10A  with the mechanism at an open position; 
       FIG. 11B  is a section taken on line  11 B- 11 B of  FIG. 11A  and inverted to an upright orientation; 
       FIG. 12  is a perspective of a wire form spring of the second embodiment; 
       FIG. 13  is an exploded perspective of a ring binder mechanism of the present invention according to a third embodiment; 
       FIG. 14  is a fragmentary perspective of the mechanism of  FIG. 13  in a closed and locked position with a housing, a mounting post, and ring members removed; 
       FIG. 15A  is a perspective of the mechanism of  FIG. 13  at a closed and locked position with a portion of a housing, a travel bar, and ring members broken away; 
       FIG. 15B  is a bottom perspective of the travel bar; 
       FIG. 16  is an exploded perspective of a ring binder mechanism of the present invention according to a fourth embodiment; 
       FIG. 17A  is a perspective of the mechanism of  FIG. 16  at a closed and locked position with a portion of a housing and ring members broken away; 
       FIG. 17B  is a bottom perspective of a travel bar of the fourth embodiment; 
       FIG. 18  is an exploded perspective of a ring binder mechanism of the present invention according to a fifth embodiment; 
       FIG. 19  is a perspective of the mechanism of  FIG. 18  at a closed and locked position; 
       FIG. 20  is the perspective to  FIG. 19  inverted; 
       FIG. 21  is a perspective similar to  FIG. 20  with the mechanism at an open position; and 
       FIG. 22  is an exploded perspective of the ring binder mechanism of  FIG. 18  illustrating an alternative method for mounting an actuating lever on a housing. 
   

   Corresponding reference characters indicate corresponding parts throughout the views of the drawings. 
   DETAILED DESCRIPTION OF THE INVENTION 
   This application contains subject matter in common with co-assigned, co-pending patent applications Ser. No. 10/870,165 filed Jun. 17, 2004 for a Soft Close Ring Binder Mechanism and Ser. No. 10/870,168 filed Jun. 17, 2004 for a Positive Lock Ring Binder Mechanism, the entire texts of which are hereby incorporated by reference. 
   Referring now to the drawings of the present invention,  FIG. 1  shows a ring binder mechanism of the present invention according to a first embodiment capable of retaining loose-leaf pages (not shown). The mechanism is generally designated by reference numeral  1  and is shown mounted on a spine  3  of a notebook having a front cover  7  and a back cover  9  hingedly attached to the spine  3 . The front and back covers  7 ,  9  move to selectively cover or expose retained pages. Ring binder mechanisms mounted on surfaces other than a notebook, however, do not depart from the scope of this invention. The mechanism  1  generally includes a housing  11 , three rings (each generally indicated at  13 ), and a control structure (generally indicated at  15 ). The housing  11  supports both the rings  13  and the control structure  15  for either closing the mechanism  1  to retain pages on the rings  13  ( FIGS. 2A and 2B ) or opening it to load pages on the rings  13  ( FIGS. 3A and 3B ). As will be described hereinafter, the control structure  15  can either directly close and lock the mechanism  1  or it can allow a spring force of the housing  11  to open the mechanism  1 . Referring to  FIG. 4 , the mechanism  1  includes a pair of hinge plates  17 ,  19  that pivot relative to the housing  11  for opening and closing the rings  13 . The control structure  15  includes an actuating lever  39 , a travel bar  21 , and three locking elements  23 ,  25 ,  27  that interact with the hinge plates  17 ,  19  to either close and lock the rings  13  or allow them to open. In addition, the mechanism  1  includes a tension spring  29  located within the housing  11  for automatically moving the travel bar  21  and locking elements  23 ,  25 ,  27  to close and lock the rings  13 . 
   The housing  11  shown in  FIG. 4  is elongate and has a symmetrically, roughly arch-shaped cross section with a raised plateau  31  at its center. The housing  11  is made of metal, but may be also made of other suitable material that is sufficiently rigid to provide a stable mount for other components of the mechanism  1  while being sufficiently resilient to function as a spring. The housing  11  has a longitudinal axis, two transversely opposite longitudinally extending edge margins, and two longitudinal ends. A bent under rim  33  formed along both longitudinal edge margins of the housing  11  includes six total slots  35  (only three of which are visible) arranged in three transversely opposed pairs along the length of the housing for receiving the rings  13  ( FIG. 2A ). At one housing end, two tabs  37  project upward for attaching the actuating lever  39 . The opposite housing end does not have a lever, although it is understood that a mechanism with a lever at each end of the housing does not depart from the scope of this invention. The raised plateau  31  includes two openings  41 ,  43 , or eyelets, for receiving and attaching mounting posts  45 ,  47  capable of securing the mechanism  1  to the notebook  5 . Differently shaped housings, including asymmetrical ones, and housings with different numbers of openings or slots do not depart from the scope of this invention. 
   The housing  11  loosely supports the two hinge plates  17 ,  19  for pivoting motion to either close the rings  13  ( FIGS. 2A and 2B ) or open the rings  13  ( FIGS. 3A and 3B ). Each ring  13  includes two ring members  49  mounted on adjacent hinge plates  17 ,  19  and movable therewith between a closed position and an open position. The ring members  49  are generally circular in cross section and are formed of suitable material such as steel. When they are in the closed position, each ring member  49  forms a substantially continuous, closed, “D”-shaped ring or loop ( FIGS. 2A and 2B ) for retaining loose-leaf pages and for allowing those pages to move along the rings  13  from one ring member  49  to the other. And when they are in the open position, each forms a discontinuous, open loop ( FIGS. 3A and 3B ) suitable for adding or removing pages. Although in the illustrated embodiment both ring members  49  can move, a mechanism having one movable ring member and one fixed does not depart from the scope of this invention. Additionally, a mechanism with more or less than three rings, or with rings that form different shapes when closed, does not depart from the scope of this invention. 
   Still referring to  FIG. 4 , each hinge plate  17 ,  19  is a thin, elongate sheet having inner and outer longitudinal edge margins, and two longitudinal ends. Each hinge plate  17 ,  19  includes seven cutouts along its inner longitudinal edge margin so that when the hinge plates  17 ,  19  interconnect, corresponding cutouts in each plate  17 ,  19  align to form openings, as shown in  FIG. 5 . A first opening  51  is located near the housing end having the lever  39  and receives a first mounting post  45  through the hinge plates  17 ,  19 . Second and third openings  53 ,  55  receive first and second locking elements  23 ,  25  respectively, as will be further discussed hereinafter. A fourth opening  61  includes two notches  63 , with one notch  63  on each hinge plate  17 ,  19 . Both notches  63  are capable of receiving a second end  65  of the tension spring  29 . A fifth opening  67  accommodates a portion of a body  69  of the tension spring  29 . A sixth opening  71  receives a third locking element  27  in identical fashion to the second and third openings  53 ,  55 . A seventh opening  75  is located near the housing end not having the lever  39  and receives a second mounting post  47  through the hinge plates  17 ,  19 . 
   The interconnected hinge plates  17 ,  19  attach to one another in parallel arrangement along their adjoining inner longitudinal edge margins, forming a central hinge having a pivot axis. The housing  11  receives the attached plates  17 ,  19  such that each plates&#39; outer longitudinal edge margin loosely fits above the housing&#39;s corresponding bent under rim  33 . Accordingly, the hinge plates  17 ,  19  are retained on the housing  11  but the edge margins are free to move within the rims  33 , allowing the plates  17 ,  19  to freely pivot about their pivot axis. The pivot axis moves up (i.e., toward the housing&#39;s raised plateau  31  as shown in  FIG. 3B ) when the hinge plates  17 ,  19  pivot to open the rings  13  and it moves down (i.e., away from the housing&#39;s raised plateau  31 ) when the plates  17 ,  19  pivot to close the rings  13 . Moreover, the hinge plates  17 ,  19  are designed to pivot in the housing  11  so that an angle A ( FIGS. 2B and 3B ) between exterior surfaces of the plates (i.e., the surfaces facing away from the housing  11 ) is always less than 180° and the pivot axis never moves to or below a coplanar position of the plates  17 ,  19  (i.e., the position where the angle A is 180°). Accordingly, the housing&#39;s spring force biases the hinge plates  17 ,  19  to pivot only for opening the ring members  49 . It does not bias the plates  17 ,  19  to pivot for closing the ring members  49 . It is to be understood, however, that in some embodiments an angle between exterior surfaces could be greater than 180° so that a spring force of a housing biases hinge plates toward a closed position. Furthermore, certain embodiments of the present invention may have hinge plates arranged to pass through a coplanar position (180°) of the hinge plates. 
   As stated previously, the housing  11  supports the control structure  15  for moving relative to the housing  11  to controllably pivot the hinge plates  17 ,  19  and securely lock the ring members  49  closed. The actuating lever  39  of the control structure, shown in  FIGS. 4 and 5 , is formed from a suitable rigid material or combination of materials, such as a metal or a plastic. It includes an enlarged head  79  to facilitate gripping and applying force to the lever  39 . A first hinge pin  81  received through upper openings  83  in the lever  39  and through the housing&#39;s tabs  37  mounts the lever  39  on the housing  11  for pivoting relative to the housing  11 . A second hinge pin  85  received through lower openings  87  in the lever  39  and through openings  89  in an intermediate connector  91  attaches the lever  39  to the connector  91 . The intermediate connector  91  connects the lever  39  to the travel bar  21  for transforming the lever&#39;s pivoting movement into substantially linear travel bar movement. Although the travel bar&#39;s movement is not perfectly linear, it is still considered to be translational motion for purposes of the present invention. 
   Referring to  FIG. 4 , the intermediate connector  91  is generally an elongate beam with a flat web and two side flanges. It includes a first end that is generally wider than a second end. More specifically, at the narrower second end the intermediate connector  91  includes a projecting tab  93  with an enlarged end  95  that is received in a slot  99  in a first end of the travel bar  21 . This travel bar end is also bent down to form a shoulder  101  against one side of which the intermediate connector  91  can bear to push the travel bar  21 . The enlarged end  95  of the projecting tab  93  is engageable with the other side of the shoulder  101  to pull the travel bar  21  toward the lever  39 . The slot  99  in which the tab  93  is received is elongate in the lengthwise direction of the travel bar  21 . Thus, the intermediate connector  91  is able to freely pivot up and down with respect to the travel bar  21 . As a result, the connector  91  transmits a linear movement to the travel bar  21  from the pivoting lever  39 . Moreover, the travel bar  21  is allowed to move up and down without hindrance from the intermediate connector  91 . The illustrated connector  91  also includes an elongate opening  103  for receiving the first mounting post  45  through the connector  91  and allowing the connector  91  to move relative to the mounting post  45 . 
   As shown in  FIGS. 4-6 , the travel bar  21  is capable of receiving the lever&#39;s pivoting motion for movement generally lengthwise of the housing  11 . The travel bar  21  is a relatively flat, elongate sheet made of a metal or other sufficiently rigid material. It is disposed generally parallel to the longitudinal axis of the housing, under the raised plateau  31  and above the hinge plates  17 ,  19 . A detent  105  is located along the travel bar&#39;s longitudinal axis and toward a second end. The detent  105  is one piece with the travel bar  21  and is struck downward from the bar&#39;s surface, forming a hook for attaching a first end  107  of the tension spring. It is understood that differently shaped travel bars, or travel bars having a detent separately attached do not depart from the scope of this invention. 
   The travel bar  21  also includes the three integral locking elements  23 ,  25 ,  27  that can either (1) cause the hinge plates  17 ,  19  to pivot for closing the ring members  49  and block the hinge plates&#39; pivoting motion for locking the ring members  49  closed or (2) allow the hinge plates  17 ,  19  to pivot for opening the ring members  49  (i.e., they can register with respective hinge plate openings  53 ,  55 ,  71 , allowing the housing&#39;s spring force to pivot the hinge plates  17 ,  19  to open the ring members  49 ). The locking elements  23 ,  25 ,  27  of the illustrated embodiment each comprise two spaced apart flanges  109  formed as one piece with the travel bar  21  and folded downward 90° from a longitudinal edge margin of the travel bar ( FIG. 6 ). Accordingly, each flange&#39;s planar surface is substantially parallel to that of every other flange and is aligned with the travel bar&#39;s longitudinal axis. In addition, a lower edge portion of each flange is angled, forming a cam surface  113  capable of engaging the hinge plates  17 ,  19  and causing them to pivot. It will be understood that locking elements may be formed as a single piece or as more than two pieces, and that control structures using more or fewer than three locking elements, or differently shaped locking elements do not depart from the scope of this invention. 
   The travel bar  21  and three locking elements  23 ,  25 ,  27  are biased to a locking position blocking the hinge plates&#39; pivoting motion by the tension spring  29 . The tension spring  29  automatically pulls the travel bar  21  and locking elements  23 ,  25 ,  27  to the locking position when the locking elements  23 ,  25 ,  27  move out of registration with respective openings  53 ,  55 ,  71  in the hinge plates  17 ,  19 . The tension spring  29  is located generally between the travel bar  21  and the hinge plates  17 ,  19 , and is partially received in the hinge plates&#39; fifth opening  67 . A tension spring is desired for such biasing action because it offers a variety of placement options within a ring binder mechanism since its axis does not need to align with a travel bar&#39;s direction of movement to cause the travel bar and locking elements to move to a locking position. 
   Now referring to  FIGS. 5 ,  7 , and  8 , the control structure  15  can selectively move the mechanism  1  between a closed and locked position ( FIG. 5 ) and an open position ( FIG. 8 ). At the closed and locked position, the ring members  49  are together and cannot be pulled apart. The hinge plates  17 ,  19  are oriented so that the angle A between their exterior surfaces is at its greatest, but still less than 180° ( FIG. 2B ) and the actuating lever  39  is relatively vertical with the travel bar  21  positioned closer to the housing end having the lever  39 . Accordingly, the first, second, and third locking elements  23 ,  25 ,  27  are located between the hinge plates  17 ,  19  and the housing  11 , and are substantially out of registration with the respective hinge plate openings  53 ,  55 ,  71 . In this position, the locking elements  23 ,  25 ,  27  firmly oppose any force tending to open the ring members  49  because they are sized, along with the travel bar  21 , to fully occupy the area between the hinge plates  17 ,  19  and the housing&#39;s raised plateau  31 . So as the hinge plates  17 ,  19  push up on the locking elements  23 ,  25 ,  27  (i.e., such as when the hinge plates  17 ,  19  pivot to open the ring members  49 ) they immediately engage the locking elements  23 ,  25 ,  27  and tend to force both the locking elements  23 ,  25 ,  27  and the travel bar  21  up. Thus, the locking elements  23 ,  25 ,  27  and the housing  11  resist the opening movement, holding the ring members  49  together. 
   To open the mechanism  1 , an operator pivots the lever  39  outward and downward ( FIG. 7 ). This pushes the intermediate connector  91  and travel bar  21  away from the housing end having the lever  39 , and moves the travel bar  21  and locking elements  23 ,  25 ,  27  out of the locking position. As the travel bar  21  and locking elements  23 ,  25 ,  27  move, the tension spring  29  extends and begins to exert a steadily increasing force, urging them back toward the locking position. But as long as the operator continues pivoting the lever  39 , the travel bar  21  and locking elements  23 ,  25 ,  27  continue to move until the three locking elements  23 ,  25 ,  27  simultaneously move into registration with the respective second, third, and sixth openings  53 ,  55 ,  71  in the hinge plates. At this intermediate transitional position, the locking elements  23 ,  25 ,  27  no longer block the hinge plates&#39; pivoting motion and the housing&#39;s spring force automatically pivots the hinge plates  17 ,  19 . The three corresponding openings  53 ,  55 ,  71  of the hinge plates pass over the locking elements  23 ,  25 ,  27  and the ring members  49  open ( FIG. 8 ). Here, the angle A between the hinge plates&#39; exterior surfaces is at its smallest ( FIG. 3B ) and a substantially vertical portion  115  (see  FIG. 6 ) of each locking element&#39;s cam surface contacts an edge of the respective opening  53 ,  55 ,  71  in the hinge plates. This blocks the locking elements  23 ,  25 ,  27  and prevents contraction of the tension spring  29  that would move the travel bar  21  back to the locking position. Moreover, the housing&#39;s spring force holds the ring members  49  open so that the operator may let go of the lever  39  and load or remove pages from the mechanism  1 . 
   To return the mechanism  1  back to the closed and locked position, the operator pivots the lever  39  inward and upward, reversing the opening action and pulling the intermediate connector  91  and travel bar  21  back toward the housing end having the lever  39 . This causes the locking elements&#39; cam surfaces  113  to engage the edges of the respective openings in the hinge plates  17 ,  19  and overcome the forces (i.e., a friction force between the locking elements&#39; cam surfaces  113  and the hinge plates  17 ,  19  and the spring force of the housing  11 ) opposing the hinge plates&#39; opening motion. Thus, the hinge plates  17 ,  19  slowly slide down each cam surface  113  and gently move the ring members  49  together. Once the ring members  49  fully close and the angle A between the hinge plates&#39; exterior surfaces is again at its greatest ( FIG. 2B ), the cam surfaces  113  disengage the edges of the openings and the tension spring  29  contracts, automatically pulling the travel bar  21  and locking elements  23 ,  25 ,  27  back to the locking position. The locking elements  23 ,  25 ,  27  fully return to their position behind the hinge plates  17 ,  19 , blocking the plates&#39; pivoting motion. The mechanism  1  may alternatively be returned to the closed and locked position by simply pushing the ring members  49  together. This pivots the hinge plates  17 ,  19  and moves the openings  53 ,  55 ,  71  therein to a position below the locking elements  23 ,  25 ,  27 , allowing the tension spring  29  to contract and pull the travel bar  21  and locking elements  23 ,  25 ,  27  back to the locking position. 
   The ring binder mechanism of the present invention effectively retains loose-leaf pages when the ring members  49  are closed, and readily prevents the closed ring members  49  from unintentionally opening. This is because the tension spring  29  automatically positions the travel bar  21  and the locking elements  23 ,  25 ,  27  in the locking position when the ring members  49  close, eliminating additional manual movement of the lever to lock the mechanism  1 . This locking characteristic exists regardless of how the mechanism  1  is closed (i.e., regardless of whether the ring members  49  are directly pushed together or whether the lever  39  is pivoted). Moreover in this embodiment, the ring members  49  do not snap together when they close because the locking elements&#39; cam surfaces  113  controllably wedge the hinge plates  17 ,  19  and gently close the ring members  49 . Also, when the mechanism  1  is closed it distributes force generally uniformly to the ring members  49  because the three locking elements  23 ,  25 ,  27  are uniformly spaced along the length of the hinge plates  17 ,  19 . Additionally, the locking elements  23 ,  25 ,  27  and travel bar  21  generally completely occupy the area between the hinge plates  17 ,  19  and the housing&#39;s raised plateau  31 , fully resisting hinge plate movement that would open the ring members  49 . As a result, the ring members are positively locked together and gaps between the ring members  49  are minimized, if not eliminated. Furthermore, this mechanism  1  opens easier than prior art mechanisms because the operator need only stretch the tension spring  29  a short distance before the locking elements  23 ,  25 ,  27  register with respective openings  53 ,  55 ,  71  in the hinge plates  17 ,  19 , allowing the housing&#39;s spring force to automatically pivot the hinge plates  17 ,  19  to open the ring members  49 . Similarly, the lever&#39;s pivoting movement reduces the magnitude of force necessary to move the travel bar  21  and locking elements  23 ,  25 ,  27  to open (or close) the ring members  49  because of the mechanical advantage given by the lever  39 . Levers that directly push or pull a travel bar, such as those associated with prior art mechanisms, must overcome additional internal friction forces before ultimately opening or closing ring members. 
     FIG. 9  illustrates an alternative version of a travel bar, generally designated by reference numeral  119 . This travel bar includes three tabs  121  (only one of which is shown) formed as one piece with the travel bar  119 . Each tab  121  is struck downward 90° from the bar&#39;s surface and receives a locking element  123  formed separately from the travel bar  119  and secured to the tab. The locking element  123  is generally block-shaped and may be made of plastic or other suitable material capable of resisting the hinge plates&#39; pivoting motion and of wedging the hinge plates  17 ,  19  to move the ring members  49  together. The locking element  123  includes an angled cam surface  125  substantially similar to that of the locking element flanges  109  of the travel bar of the first embodiment. Consequently, each embodiment described herein may include this alternative travel bar  119 . 
     FIGS. 10A-12  show a second embodiment of a ring binder mechanism of the present invention, substantially as described above and shown in  FIGS. 1-8 . The mechanism is generally indicated at  201 , and parts of this mechanism corresponding to parts of the mechanism of the first embodiment are indicated by the same reference numerals, plus “200”. This embodiment is similar to the first embodiment, but includes two wire form springs  327  attached to an underside of interconnected hinge plates  217 ,  219 . The springs  327  urge the plates  217 ,  219  to pivot for opening ring members  249  when locking elements  223 ,  225 ,  227  register with respective openings  253 ,  255 ,  271  in the hinge plates  217 ,  219 . Also in this embodiment, the hinge plates&#39; pivot axis moves below a coplanar position (180°) of the hinge plates when the hinge plates  217 ,  219  pivot to close the ring members  249 . Accordingly, the angle A made by the exterior surfaces of the hinge plates  17 ,  19  is greater than 180° in this position ( FIG. 10B ). 
   To receive the wire form springs  327 , each hinge plate  217 ,  219  includes two notches  329  and one cutout  331  along its outer longitudinal edge margin (the notches  329  and cutout  331  are only visible on one hinge plate  219 ). The notches  329  are arranged in side-by-side fashion, defining a tab therebetween, and are located toward one end of the hinge plate; the cutout  331  is located toward the other end of the hinge plate. The tab and the cutout  331  are oriented in reverse order on the two hinge plates  217 ,  219  so that when the two plates  217 ,  219  interconnect, one plate&#39;s tab is across from the other plate&#39;s cutout  331 . 
   As shown in  FIGS. 10A ,  11 A, and  12 , the wire form spring  327  is a generally round wire formed roughly into an elongate octagon with an open end and a closed end (the open end forming one of the sides of the octagon). The closed end is bent upward 90° and fits over the tab and into the two notches  329  of one of the interconnected hinge plates  217 ,  219 . The free end of the tab is received behind a rim  233  of a housing so that the closed end of the spring  327  is held on the tab. The open end of the spring  327  includes two wire tips  335  that are each bent twice into a hook shape. A first bend is 90° upward and a second bend is 90° outward. The tips  335  releasably fit into the cutout  331  of a second interconnected hinge plate  217 ,  219  so that a body of the attached wire form spring is positioned substantially underneath the interconnected plates  217 ,  219 . In this attached position, the wire form springs  327  are relaxed when the hinge plates  217 ,  219  are oriented with the ring members  249  open. The body of the wire form spring  327  is bowed slightly upward (i.e., toward the interconnected plates  217 ,  219  ( FIG. 11B )) so that exterior surfaces of the interconnected hinge plates form an angle A that is less than 180° (i.e., the hinge plates&#39; pivot axis is above the coplanar position (180°) of the hinge plates  217 ,  219 ). When the locking elements  223 ,  225 ,  227  move the hinge plates  217 ,  219  down and through the coplanar position (180°) to close the ring members  249 , each bowed wire form spring  327  flattens and stresses ( FIG. 10B ). When the locking elements  223 ,  225 ,  227  move back into registration with corresponding openings  253 ,  255 ,  271  in the hinge plates, the stressed wire form springs  327  automatically act on the hinge plates  217 ,  219  and pivot them up and through the coplanar position (180°), opening the ring members  249 . Because the wire form springs  327  bias the hinge plates  217 ,  219  to open the ring members  249 , the housing&#39;s spring force in this embodiment may be somewhat smaller than in typical prior art mechanisms, making it easier to close this mechanism  201 . It is understood that while the illustrated mechanism  201  includes two wire form springs  327 , mechanisms having fewer than two or more than two wire form springs do not depart from the scope of this invention. 
   A third embodiment of the present invention is shown in  FIGS. 13-15  and is designated generally by reference numeral  401 . Parts of this embodiment that correspond to parts of the first embodiment are indicated by the same reference numerals, plus “400”. This embodiment is again similar to the first embodiment. As shown in  FIGS. 13 and 14 , it includes an actuating lever  439  similar to that of the mechanism  1  of the first embodiment, but that is capable of directly pivoting hinge plates  417 ,  419  for opening and closing ring members  449 . In this mechanism  401 , the lever  439  includes a closing arm  549  and an opening arm  551  for engaging the hinge plates  417 ,  419  to pivot them and move the ring members  449 . The two arms  549 ,  551  extend generally perpendicular from the lever  439  and are generally parallel to one another. They are separated by a channel that receives a finger  555  ( FIG. 13 ) of each hinge plate. Each finger  555  extends from an end of the hinge plate and is somewhat narrower than the rest of the hinge plate. When the hinge plates  417 ,  419  are positioned for pivoting motion in the housing  411 , the fingers  555  jut out from the housing  411  and position in the lever&#39;s channel, allowing the lever  439  to drive the hinge plates for pivoting movement. 
   This mechanism  401  also includes an alternative intermediate connector in the form of a wire link  541 . The wire link  541  is a thin wire having two ends that are both bent 90° in the same direction ( FIG. 13 ) for connecting the actuating lever  439  to a travel bar  421 . One end of the wire link is received in an aperture  547  in the closing arm  549  of the lever. The other end of the link is received in a slot  539  in one of two side flanges of the travel bar, where the side flanges  537  are formed by folding a section of both longitudinal edge margins of the travel bar downward 90°. As a result, the lever  439  can be moved a distance corresponding to the movement of the end of the link  541  through the length of the slot  539  without causing corresponding movement of the travel bar  421 . It is feasible that two wire links could be employed. But it is understood that when one wire link is used, it can be positioned in a slot of either side flange without departing from the scope of the present invention. Similarly, mechanisms having only one slot or only one side flange do not depart from the scope of this invention. 
   As in prior embodiments, the actuating lever  439  of this mechanism  401  pivotally attaches to one end of a housing  411 . The housing  411  includes two tabs  527  ( FIG. 13 ) projecting downward from one housing end for receiving a hinge pin  529  to attach the lever  439 . In addition, a raised plateau  431  of the housing  411  includes two openings  531  for receiving and attaching grooved rivets  533 . Now referring particularly to  FIG. 15A , the rivets  533  (only one of which is shown) slidably connect the travel bar  421  to the housing  411  through two slots  534  on the surface of the travel bar, permitting the travel bar  421  to move relative to the rivets  533  and generally lengthwise of the housing  411 . This minimizes vertical movement of the travel bar  421  and its associated locking elements  423 ,  425 ,  427  when the hinge plates  417 ,  419  pivot to open or close the ring members  449  (i.e., this beneficially prevents the locking elements  423 ,  425 ,  427  from engaging a notebook&#39;s spine  403  (not shown) when the mechanism  401  is at an open position). Furthermore in this embodiment, the openings in the hinge plates are ordered slightly differently than in the first and second embodiments, accommodating a tension spring  429  oriented in this embodiment to bias the travel bar  421  and locking elements  423 ,  425 ,  427  away from the housing end having the lever  439 . A first opening  557  is located near the housing end having the lever  439  and receives a first mounting post  445  through the hinge plates  417 ,  419 . A second opening  559  receives a first locking element  423 . A third opening  561  accommodates a body  469  of the tension spring. A fourth opening  563  includes notches  463  ( FIG. 13 ) for receiving a second end  465  of the tension spring. Fifth and sixth openings  565 ,  567  receive second and third locking elements  425 ,  427 , and a seventh opening  569 , located near the housing end not having the lever  439 , receives a second mounting post  447  through the hinge plates  417 ,  419 . 
   At a closed and locked position ( FIG. 15A ) in this embodiment, the hinge plates  417 ,  419  are oriented with a pivot axis below a coplanar position (180°), and the travel bar  421  and locking elements  423 ,  425 ,  427  are relatively away from the housing end having the lever  439  (as compared to their positions in the first and second embodiments). When the lever  439  pivots for opening the mechanism  401 , it pulls the wire link  541 , travel bar  421 , and locking elements  423 ,  425 ,  427  toward the housing end having the lever  439 . But when the locking elements  423 ,  425 ,  427  register with the respective second, fifth, and sixth openings  559 ,  563 ,  567  in the hinge plates, the plates  417 ,  419  do not automatically pivot. The housing&#39;s spring force prevents it. Instead, the lever&#39;s opening arm  551  engages the undersides of the hinge plate&#39;s fingers, forcing the hinge plates  417 ,  419  to pivot upward and through the coplanar position (180°). Openings  559 ,  563 ,  567  in the hinge plates move over the corresponding locking elements  423 ,  425 ,  427  and the ring members  449  open. When the mechanism  401  is closed, the lever&#39;s closing arm  549  engages a top sides of the hinge plates&#39; fingers, slowly pivoting the hinge plates  417 ,  419  downward and through the coplanar position (180°). The tension spring  429  contracts and pulls the travel bar  421  and locking elements  423 ,  425 ,  427  toward the housing end having the lever  439  (i.e., to the locking position). In this embodiment, the closing arm  549  alone pivots the hinge plates  417 ,  419  for closing the ring members  449 . The locking elements  423 ,  425 ,  427  do not cam the plates  417 ,  419  to pivot unlike their counterparts in the first and second embodiments. 
     FIGS. 16-17B  show a fourth embodiment of the present invention. The mechanism of this embodiment is generally described by reference numeral  601 . Parts of this embodiment corresponding to parts of the first embodiment are indicated by the same reference numerals, plus “600”. Parts corresponding to parts of the third embodiment, not included in the first embodiment, are indicated by the same reference numerals, plus “400”. This embodiment is substantially similar to the third embodiment. But in this embodiment a first end  707  of a tension spring attaches to a travel bar  621  while a second end  665  attaches to a detent  735  in a raised plateau  631  of a housing. 
   Also in this embodiment, the travel bar  621  is shaped as a rigid channel having a flat web and two side flanges. It includes three locking elements  747  that each include two locking flanges  749  integrally attached to side flanges of the travel bar. The locking flanges  749  project downward from the side flanges at uniformly spaced longitudinal intervals so that three locking flanges  749  are on each side of the travel bar. A first pair of locking flanges are located toward the housing end having the actuating lever  639  and include a slot  751  for receiving one end of a wire link  941 , which acts to connect the travel bar  621  to the actuating lever  639 . The travel bar  621  further includes two additional openings  731 ,  733  in the web to accommodate the tension spring&#39;s alternate connection to the travel bar  621  and the housing  611 . A first additional opening  731  is located near a longitudinal center of the travel bar and receives the tension spring&#39;s first end  707 . A second additional opening  733  is located between the first additional opening  731  and a travel bar slot  934 , and receives a portion of a tension spring body  669 . Because the tension spring  629  does not attach to hinge plates  617 ,  619 , the plates  617 ,  619  include only four openings (FIG.  17 A). A first opening  651  is located near the housing end having the lever  639  and receives a first mounting post  645  through the hinge plates  617 ,  619 , and second, third, and fourth openings  653 ,  655 ,  671  receive the three respective locking elements  747 . 
   Moreover in this embodiment, the actuating lever  639  is identical to that of the mechanism of the third embodiment, but mounts on a separate lever mount  741 . The lever mount  741  includes two downwardly projecting tabs  743  that receive a hinge pin  745  for mounting the lever  639  on the housing  611 . The lever mount  741  attaches to the housing  611  by a rivet passing through an opening  737  in the housing&#39;s raised plateau  631 . In all other aspects, this mechanism  601  operates identically to the mechanism  401  of the third embodiment. 
   In  FIGS. 18-22 , a fifth embodiment of a ring binder mechanism of the present invention is shown (designated generally by reference numeral  1001 ) substantially as described above and illustrated in the figures. In particular, the mechanism is substantially similar to the mechanism  601  of the fourth embodiment illustrated in  FIGS. 16 through 17B , but for the modifications described hereinafter. Parts of this mechanism corresponding to parts of the mechanism of the fourth embodiment are indicated by the same reference numerals, plus “400.” Referring now to  FIGS. 18 and 19 , this mechanism  1001  includes an actuating lever  1039  similar to the lever  639  described for the mechanism  601  of the fourth embodiment. It mounts on a separate lever mount  1141  at one longitudinal end of a housing and includes a closing arm  1349  and an opening arm  1351  for engaging fingers  1355  of hinge plates to open and close ring members  1049 . But in this mechanism  1001 , the lever  1039  is “T”-shaped with an elongate, enlarged head  1079  having a length oriented generally parallel to a longitudinal axis of the housing. The head  1079  is integral with the lever  1039  and ends of the head are bowed slightly upward to facilitate gripping and applying force to the lever  1039 . It is to be understood, however, that the actuating lever  1039  may be directly mounted on the housing  1011  (see  FIG. 22 ), as described for the mechanism  401  of the third embodiment and illustrated in  FIGS. 13 through 15 , without departing from the scope of the present invention. 
   As with the actuating lever  1039 , a travel bar  1021  of this mechanism is also similar to the travel bar  621  of the mechanism of the fourth embodiment. But in this mechanism  1001 , as shown in  FIGS. 18 and 21 , the travel bar  1021  includes three generally block-shaped locking elements  1147  that are integrally attached to a web of the travel bar and project downward therefrom at uniformly spaced longitudinal intervals. It is to be understood, however, that mechanisms with locking elements separately attached to a travel bar do not depart from the scope of the present invention. The locking elements  1147  include relatively flat side surfaces and a bottom surface that tapers to a narrow central area (see  FIG. 21 ). Locking elements of other configurations do not depart from the scope of the present invention. A first locking element  747  is located toward an end of the housing having the lever  1039  and includes a slot  1151  for receiving a hook-shaped end of a wire link  1341 , connecting the travel bar  1021  to the actuating lever  1039  in substantially similar fashion to the wire link  941  of the mechanism of the fourth embodiment. 
   As shown in  FIGS. 18 ,  20 , and  21 , the hinge plates  1017 ,  1019  of this mechanism are also substantially similar to those of the mechanism of the fourth embodiment, but include a bent tab  1163  in each cutout. The tabs  1163  substantially prevent formation of burrs along edges of the cutouts (burrs often form on the edges of the cutouts when the cutouts are made in the hinge plates  1017 ,  1019 ). When the hinge plates  1017 ,  1019  interconnect, the tabs  1163  of corresponding cutouts are adjacent and are positioned in second, third, and fourth openings  1053 ,  1055 ,  1071  of the hinge plates. In particular, the tabs are located on an edge of each opening over which the corresponding block-shaped locking element  1147  passes as it moves between a position in registration with the opening and a position out of registration. Thus, the tabs  1163  aid movement of the block-shaped locking elements  1147  into and out of registration with the second, third, and fourth openings  1053 ,  1055 ,  1071  of the hinge plates and prevent excessive wear of the locking elements  1147  as they repeatedly slide over the respective edges of those openings. It is to be understood that these tabs  1163  can be used generally with the hinge plates of each mechanism described herein, and are not limited to the hinge plates  1017 ,  1019  of the mechanism of this embodiment. 
   Some other differences between this mechanism  1001  and the mechanism  601  of the fourth embodiment include that in this mechanism  1001  the ring members  1049  extend from a top surface of each hinge plate for movement between a closed position and an open position. Also in this mechanism  1001 , in the closed position the ring members  1049  form a substantially continuous, closed, circular ring or loop (see  FIG. 19 ) for retaining loose-leaf pages and for allowing those pages to move along rings  1013  from one ring member  1049  to the other. Ring binder mechanisms having other ring member configurations do not depart from the scope of the present invention. 
   Referring now to  FIGS. 20 and 21 , operation of this mechanism is substantially similar to operation of the mechanism of the fourth embodiment. To open the ring members  1049 , an operator engages an end of the lever&#39;s elongate head furthest from the housing  1011 , causing the lever  1039  to pivot outward and downward. This pulls the wire link  1341  and travel bar  1021  toward the end of the housing having the lever  1039 , moving the locking elements  1147  into registration with the corresponding openings  1053 ,  1055 ,  1071  of the hinge plates. The opening arm  1351  of the lever engages the fingers  1355  of the hinge plates and causes the plates  1017 ,  1019  to pivot upward to open the ring members  1049 . To close the ring members  1049 , the operator engages an opposite end of the lever, causing the lever  1039  to pivot upward and inward. The closing arm  1349  engages the fingers  1355  of the hinge plates and pivots the plates  1017 ,  1019  downward and over the locking elements  1147 , closing the ring members  1049  and allowing a tension spring  1029  to pull the travel bar  1021  back to a locking position. 
   Components of the several embodiments of the ring binder mechanism of the present invention are made of a suitable rigid material, such as a metal (e.g. steel). But mechanisms having components made of a nonmetallic material, specifically including a plastic, do not depart from the scope of this invention. 
   When introducing elements of the present invention or the preferred embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Moreover, the use of “up” and “down” and variations of these terms is made for convenience, but does not require any particular orientation of the components. 
   As various changes could be made in the above without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.