Abstract:
An upper piggybacked unit of a tandem unit is provided with a hinge unit and at least one motion lock to prevent the upper unit from falling away from the lower unit when it is tandemly coupled to the lower unit and the lower unit is pivoted to a non-horizontal position. The motion lock may inhibit rotation and/or translation of the upper unit. The motion lock may also be self-actuating, such as a gravity dependent lock mechanism. A lock override mechanism may be provided to allow the lock to yield to excessive force without causing damage. The lock enable condition may be automatically reset after the override condition so that no special knowledge or action on the part of the user is required to return the hinge to normal operation. The motion locks are particularly useful when provided on a reprographic device, such as a copier, facsimile, printer or malfunction device having an upper unit that forms a sheet feeder unit, a lower unit that forms a scan housing, and a fixed base below the lower unit that may contain a marking engine.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The invention relates to a hinge assembly for use in a tandem pivot structure that has one or more tandem motion locks and a lock override. The hinge assembly is particularly suited for use in a reprographic device having two separately rotatable units provided in a piggyback fashion. 
     2. Description of Related Art 
     Printers, copiers, facsimiles and other reprographic products typically have a cover or structural housing that has to be pivoted open to gain access to internal components, such as for ink or toner replenishment, media jams, etc. Copiers and multifunctional printers and devices with printing, scanning and/or copying functions have additional requirements for pivoting covers. Such multifunction devices besides having printing mechanisms may also include scanning mechanisms and may have a feed unit with automatic document feeding mechanisms. The feed unit is normally oriented in a nearly horizontal position. Such feed units must be pivoted open to access a scanner platen glass for document copying or media jam recovery. 
     The feed unit may be tandemly coupled in piggyback fashion to a lower structure, which incorporates the scanner and also pivots. This lower scanner unit is also normally oriented in a nearly horizontal position. An example of this is shown in simplistic form in  FIGS. 1-2 . Printer device  100  includes an upper rotatable feed unit  110  coupled to a rotatable lower scanner unit  130  through a first coupling hinge  120 . The rotatable lower scanner unit  130  is rotatable relative to the lower base of printer  100  through a second coupling hinge  140 . Thus, two tandem hinges are provided that can each be independently rotated. However, when the lower scanner unit  130  is pivoted fully open to provide access to the interior of the printer device  100 , a problem may arise as shown in  FIG. 2 . That is, the upper feeder unit  110  may want to pivot further, possibly falling behind the device due to the influence of gravity and/or inertial motion caused by the opening of the lower scanner unit. 
     If the lower scanner unit is intended to accommodate books with the upper feeder unit closed, a vertical slide or elevating range can be provided to accommodate the thickness of the book on the scanner unit. Such an elevating capability can create additional problems when the scanner unit is opened fully because now the feeder unit, if not restrained, can extend in translation backwards with undesired force and consequences, due to gravity and momentum. 
     When an unrestrained feeder unit  110  falls backwards due to pivot motion allowed by the first coupling hinge  120  or by unrestrained translation of an elevating slide, the feeder unit  110  can strike a wall behind the printer device  100 , or a person walking behind it. Moreover, when the feeder unit  110  freely falls backwards, the feeder unit  110 , first connecting hinge  120  and/or hinge mounting components can be bent or damaged. 
     All of these problems are brought about due to integration of functions added to printers when they require multipurpose functionality. User interface unpredictability can also be part of the problem. Users of the device may ignore motion tendencies of the various cover mechanisms they are opening. The propensity to be casual and inattentive when opening and handling of the various device units being pivoted can lead to yet another problem. The hinge may not be opened far enough to optimally accomplish the desired task, such as jam removal or ink replenishment. 
     Accordingly, structures for accommodating tandem pivoting units may suffer from various problems. 
     SUMMARY OF THE INVENTION 
     In accordance with a first aspect of the invention, at least one motion lock is provided on the upper piggybacked unit of a tandem unit to prevent the upper unit from falling away from the lower unit when it is tandemly coupled to the lower unit and the lower unit is pivoted to a non-horizontal position. 
     In various exemplary embodiments, this aspect is achieved using a gravity dependent lock mechanism. Moreover, in a preferred embodiment, the lock is self-actuating and self-releasing upon sufficient pivoting of the upper and lower units. 
     In various exemplary embodiments, the motion lock prevents rotational movement of the upper unit relative to the lower unit. In other various exemplary embodiments, the motion lock prevents translatory motion of the upper unit relative to the lower unit. In a preferred embodiment, motion locks are provided that prevent both rotational and translatory movement of the upper unit relative to the lower unit. In a more preferred embodiment, the motion locks are automatically enabled or disabled so that no special knowledge or action on the part of the user is required to return the hinge to normal operation. 
     In various exemplary embodiments a hinge pivot motion lock for a hinge that tandemly couples an upper unit to a lower unit will automatically inhibit pivot motion of the upper unit as the lower unit is pivoted into an intermediate range of positions between a first position (e.g., a closed position) and a second position. Moreover, the motion lock will automatically disengage and allow the upper unit to pivot freely when the lower unit is oriented at or near the first position, such as a closed substantially horizontal position. 
     This motion lock solution, however, may lead to another problem. When the large geometry of the typical media feed mechanism forming the upper unit is grasped by a user, the leverage advantage and torque that can be applied in opposition to a locking position that is near a pivot center of the hinge can be tremendous. Users are not very likely to intentionally open the unit with excessive force. However, because of this leverage, the unit could inadvertently be opened with force that would otherwise damage or break the lock mechanism locking the hinge to a vertical position. This may break the hinge mount or other components of the device. 
     In accordance with a second aspect of the invention, a lock override mechanism is provided to reduce or prevent the above problem. Such a lock override mechanism allows the lock to yield to excessive force without causing damage. In a preferred embodiment, the lock enable condition is automatically reset after the override condition so that no special knowledge or action on the part of the user is required to return the hinge to normal operation. 
     In exemplary embodiments, the motion locks are provided on a reprographic device, such as a copier, facsimile, printer or multifunction device having an upper unit that forms a sheet feeder unit, a lower unit that forms a scan housing, and a fixed base below the lower unit that may contain a marking engine. 
     In accordance with a further aspect of the invention, the various motion locks and/or override mechanisms are provided inside an exterior housing of the hinge assembly so that, with a cursory glance, the hinge assembly has the outward visual appearance of an ordinary hinge. Besides improved aesthetics, this elimination of external linkages, release catches, etc. can remove sources of potential interference that would otherwise impede proper operation of the device, and can improve product safety. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various exemplary embodiments will be described in detail, with reference to the following figures, wherein: 
         FIG. 1  illustrates a conventional reprographic device comprising a tandem pivot structure in which two separate pivoting units are tandemly coupled and independently rotatable; 
         FIG. 2  illustrates the conventional reprographic device of  FIG. 1  when the lowermost pivotable unit has been fully raised to a substantially vertical position and the uppermost unit is indirectly moved to an undesirable position as a result of movement of the lowermost pivotable unit; 
         FIG. 3  illustrates an exemplary reprographic device according to an embodiment of the invention comprising a tandem pivot structure in which two separate pivoting units are tandemly coupled and rotatable, in which an upper hinge is provided with at least one motion lock that is dependent on the orientation of the lower unit for actuation; 
         FIG. 4  illustrates the exemplary reprographic device of  FIG. 3  when the lowermost pivotable unit remains closed and the upper most pivotable unit is independently positioned in an open position; 
         FIG. 5  illustrates the reprographic device of  FIG. 3  when the lowermost pivotable unit has been fully raised to a substantially vertical position and the uppermost unit is constrained against inadvertent pivotal and/or translational motion by the at least one motion lock; 
         FIG. 6  illustrates an exemplary reprographic device according to an embodiment of the invention comprising a tandem pivot structure in which two separate pivoting units are tandemly coupled and rotatable, in which an upper unit is capable of vertical translatory movement and provided with at least one motion lock, which is dependent on the orientation of the lower unit; 
         FIG. 7  illustrates the reprographic device of  FIG. 6  when the lowermost pivotable unit is being raised to a pivoted non-horizontal position and the uppermost unit is constrained against inadvertent translational motion by the at least one motion lock; 
         FIG. 8  illustrates an exemplary reprographic device according to an embodiment of the invention in which the tandem pivot structure is further provided with an override feature that overrides the motion lock to allow the upper unit to pivotably break away from the lower unit upon receiving a sufficient force; 
         FIG. 9  illustrates an exemplary embodiment of a preferred upper hinge assembly in a closed position; 
         FIG. 10  illustrates an exemplary embodiment of the upper hinge assembly of  FIG. 9  in a fully open position; 
         FIG. 11  illustrates an exploded view of the hinge assembly of  FIGS. 9-10 ; 
         FIG. 12  illustrates a partial cut-away view of an upper hinge assembly according to a preferred embodiment in a raised position and the lower unit of the reprographic device being in a substantially horizontal position; 
         FIG. 13  illustrates a partial cut-away view of an upper hinge assembly according to a preferred embodiment in a closed, horizontal position and an elevated slide unrestrained from vertical movement but restrained from unintended removal; 
         FIG. 14  illustrates a partial cut-away view of the upper hinge assembly according to a preferred embodiment in a non-raised position relative to the lower unit and the lower unit of the reproduction device being in a raised, non-horizontal position in which a first motion lock mechanism prevents rotation of the upper unit relative to the lower unit and a second motion lock mechanism prevents translational movement of the upper unit relative to the lower unit; 
         FIG. 15  illustrates a partial cut-away view of the upper hinge assembly of  FIG. 14  with an override mechanism activated upon receipt of a sufficient leverage force acting on the upper unit that overrides the first motion lock mechanism and allows rotation of the upper unit relative to the lower unit; and 
         FIG. 16  illustrates major hinge cam positions achieved by an exemplary hinge assembly. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIGS. 3-5  illustrate an exemplary tandem pivoting device  200  useable with various exemplary embodiments of the systems and methods described. In an exemplary embodiment, device  200  may be a reprographic device, such as a copier, printer, facsimile, or other similar device, and is preferably a multifunction device capable of scanning, as well as providing copying, printing, and/or facsimile transmission functionality. Reprographic device  200  includes an upper pivoting unit  210 , a lower pivoting unit  220 , a first coupling hinge assembly  300  that pivotally couples the upper pivoting unit  210  to the lower pivoting unit  220 , and a second coupling hinge assembly  400  that pivotally couples the lower unit  220  relative to a base  230  of the device. 
     The upper pivoting unit  210  may form an upper feeder unit having an auto feeding module that advances a recording media, such as paper, past a scanning head or scan platen. In an exemplary embodiment, the lower pivoting unit  220  forms a lower scan unit that contains the scanner platen. The scanned images can be reproduced by a marking engine provided in, for example, base  230 . 
     First coupling hinge assembly  300  allows rotational movement of upper pivot unit  210  between a substantially horizontal closed position ( FIG. 3 ) and a substantially vertical fully open position ( FIG. 4 ). However, unit  210  may also be positioned at one or more intermediate positions. Second coupling hinge assembly  400  likewise allows rotation of lower pivoting unit  220  between a closed substantially horizontal position ( FIG. 3 ) and an open position ( FIG. 5 ), which could be a fully open substantially vertical position, but preferably is a position less than vertical but sufficient to enable access to lower base device  230 . Unit  220  may also be opened to one or more intermediate positions. Although second coupling hinge assembly  400  can operate independent of operation of the first coupling hinge assembly  300 , first coupling hinge assembly  300  has movement operations that are at least partially dependent on the orientation or operation of the lower pivoting unit  220 . 
     One important feature of this is shown in  FIG. 5  where during opening of the lower pivoting unit  220  to a non-horizontal position, the first coupling hinge assembly  300  has its motion constrained by a first motion lock  500 , to be described later in more detail with reference to  FIGS. 12 and 14 . This first motion lock  500  in an exemplary embodiment constrains further rotation of the upper feeder unit  210  relative to lower scan unit  220  and is preferably a gravity-actuated lock. Accordingly, when the lower scan unit  220  is opened, the upper feeder unit will not inadvertently fall away from the scan unit. 
     With reference to  FIGS. 6-7 , the exemplary tandem pivoting reprographic device  200  may further include an elevator slide mechanism  600  capable of freely translating the upper unit  210  substantially perpendicular to the lower unit  220  in the direction of the arrow. In this example, movement is substantially vertical. In the context of a reprographic device  200 , the upper unit  210  may be a cover or feeder unit that covers a scanning platen provided on the lower scan unit  220 . When copying individual sheets, upper unit  210  can be located very near lower scan unit  220 . However, to accommodate copying of a book or other thick document, it is necessary for the upper unit  210  to be extendible to accommodate the book while the upper unit  210  remains closed. 
     A problem arises that during the opening of the lower unit (i.e., movement to a non-horizontal position), the elevator slide mechanism  600  may be inadvertently translated due to gravity, inertia and the like. To prevent this from occurring, another aspect of the invention provides a second motion lock  700  that constrains translational movement of the elevator slide  600  (i.e., substantially limits or prevents unconstrained movement in the direction of the arrow) when the lower scan unit  220  is moved to a non-horizontal position. Second motion lock may also allow some limited degree of motion to occur before engagement. The second motion lock  700  will be described later in more detail with reference to  FIGS. 13 and 14  and also is preferably a gravity-dependent lock. 
     With reference to  FIG. 8 , another aspect of the hinge is the provision of an override mechanism  800  that overrides the constraint acting on the first coupling hinge assembly  300  by at least the first motion lock  500 . For example, when no or little force F is directly applied to the upper unit  210  during opening of the lower unit, the device operates as illustrated in  FIG. 5 . However, when an urging force F of sufficient strength acts on the upper unit  210  itself in a direction opposing constraint by the first motion lock  500 , it is possible that such force may break or damage one or more hinge assembly components or the upper unit  210  itself. This is particularly the case when the upper unit  210  has a large geometry, as in a typical media feed mechanism. With such a large geometry, the leverage advantage and torque that can be applied in opposition to the locking function, which is provided near the pivot center, is very large and it is quite possible that a sufficiently large force would be inadvertently applied. To reduce the possibility for such damage, the override mechanism  800  allows for movement of the upper unit  210  relative to the second unit  220  and a release of the first motion lock  500 . Preferably, upon reduction or elimination of the urging force F, the override mechanism  800  will automatically release, enabling the first motion lock  500  to again constrain movement as desired. 
     With reference to the preceding Figures, the first coupling hinge assembly  300  and/or hinge assembly  400  may be a counter balance style spring loaded hinge that is capable of retaining the unit open in intermediate positions by a designed counterbalance of spring force relative to weight and geometry. Either unit  210  or  220  may be capable of self-bias towards the open position (auto-open) when the unit is positioned sufficiently close to the open position. Additional features will be described with reference to  FIG. 16 . 
       FIGS. 9-11  illustrate an exemplary coupling hinge assembly  300  according to an embodiment of the invention. Hinge  300  includes a lower hinge housing  305  and upper hinge housing  310 . Upper housing  310  includes an upper housing cam follower tension spring  315  and a cam follower plunger  320 . Upper housing  310  is connected to lower housing  305  through a gear assembly that includes gear sectors  325  mounted on gear sector shaft  330  and triple gear  335  mounted on triple gear shaft  340 . 
     Lower housing  305  includes an upper surface that forms a cam profile  350  with a suitable cam contour to guide cam follower  320  and control the movement of the upper housing  310  of hinge assembly  300  relative to the lower housing  305 . Additional details of the cam profile will be described later with respect to  FIG. 16 . 
     Lower housing  305  is preferably hollow and contains a first motion lock  500  substantially within its interior confines. First motion lock  500  includes a motion lock housing  510  that is pivotally mounted within lower housing  305  by pivot shaft  550  provided in the lower half of lock housing  510 . First motion lock  500  is designed to be oriented in a first position remote from the gear assembly when the lower housing  305  is substantially vertically oriented. However, when the lower housing is tilted in a first direction, the motion lock assembly pivots into a second position in which it engages one or more components of the gear assembly  335  to lock the upper housing  310  from rotation relative to the lower housing  305 , as will be described in further detail below. 
     A second motion lock  700  is also provided in lower housing  305  and includes a body element comprised of a lower body portion  710  and an upper body portion  730  pivotally mounted on a pivot shaft  720 . The lower body is shaped, weighted or otherwise configured to be heavier than the upper body. 
     A more detailed explanation of the hinge assembly  300  will be described with reference to  FIGS. 12-15 . In  FIG. 12 , the hinge assembly  300  is shown in a standard operating position in which the lower unit  220  is closed (e.g., in a substantially horizontal position), the lower housing  305  is in a substantially vertical position, and the upper housing  310  attached to upper unit  210  is free to pivot upward in the direction of the arrow, or return to a closed position. When in this shown orientation, the first motion lock  500  becomes positioned by virtue of its center of gravity in a normal position where pivot lock  540  is disengaged from the gear assembly, and in particular displaced relative to gear  335  (i.e., displaced laterally as shown). Thus, the gear assembly (gear  335  and gear segments  325 ) is free to rotate when a force is applied to the upper unit  210 . Also, the lock function is inhibited automatically when the lower unit is closed. 
     A preferred embodiment uses gear  335  provided on hinge pivot shaft  340  that is engaged by a pivot lock  540  of the spring-loaded pivot arm  520  when the hinge is pivoted at an elevated angle best viewed in  FIG. 14 . When the pivot lock  540  engages gear  335 , pivot motion is inhibited, accomplishing the intended lock function. Other structures are possible, such as the use of compound or tandem gears to achieve a desired force ratio or strength. Alternatively, gear-like teeth may be provided over only a functional segment of a rotating component. 
     The upper unit is rotatable between closed and fully opened positions, which may be defined by the configuration of cam profile  350  and associated cam follower  320 , which may include a cam follower surface  322 . Additionally, by selection of a suitable spring force range for spring  315 , the hinge assembly can be of the counter balance type that can retain the assembly positioned in an intermediate position, such as the position shown in  FIG. 12 . Of course, the spring size and force will depend on the weight and leverage applied by the upper unit  210 . 
     As also shown in  FIG. 12 , elevator slide mechanism  600  is positioned in a first substantially vertical orientation. Slide mechanism  600  includes vertical side walls  610 , of which at least one wall includes a series of teeth or latch elements  620 . In this normal orientation, second motion lock  700  is naturally oriented by gravitational force and lock shape to a first position out of engagement with teeth elements  620 . In this position, the elevator slide mechanism  600  is capable of at least limited vertical movement as shown in  FIG. 13  to accommodate the positioning of books or the like on the platen surface of the lower scan unit  220 . However, it may be desirable to provide a releasable mating latch element  630  that at least engages with an uppermost one of the latches  620  or other upper catch feature so that the upper unit is not inadvertently removable during normal operation. However, such a latch element  630  may be manually releasable to enable full removal, for maintenance or replacement purposes. Thus, when the lower unit  220  is closed, the upper unit  210  is freely movable in rotation and translation. 
     When the lower unit  220  is positioned in a non-horizontal orientation, however, as shown in  FIG. 14 , the first and second motion locks  500 ,  700  engage. That is, in this orientation, gravity rotates second motion lock  700  to a position in engagement with one of the teeth  620 . This temporarily locks the elevator slide mechanism  600  from further translation. Then, upon return of the lower scan unit  220  to the closed (i.e., substantially horizontal) position, gravity will return the second motion lock  700  to the non-engaged position automatically. 
     Thus, the upper feeder unit  210  can be prevented from sliding outwardly or extending when the lower scan unit  220  is raised through use of a pivoting weighted pawl serving as second motion lock  700 . However, to retain elevator operation when the lower scan unit  220  is closed using a gravity-actuated pivot, the pivot lock is inhibited merely by return of the lower scan unit  220  to the closed position. Multiple catches or teeth  620  are preferably provided to prevent further elevation motion should the feeder unit  210  be partially elevated when the scanner unit  220  is lifted. 
     Additionally, while the lower scan unit  220  is in a non-horizontal orientation, the first motion lock  500  automatically engages. Again, actuation may be gravity fed, with the center of gravity of the pivot automatically moving the first motion lock into engagement with gear  335  when the lower scan unit  220  is rotated. In a preferred embodiment, pivot lock  540  is shaped so as to be received between adjacent teeth of gear  335 . This will lock the gear  335  from further rotation, which locks the upper feeder unit  210  from rotation as well. Spring  560  provides a sufficient force on the pivot arm  520  to restrain the pivot lock  540  in engagement with gear  335  against gravitational and casual user induced rotational forces on the upper pivoting unit  210 . 
     Thus, whenever the lower scan unit  220  is rotated, the upper feeder unit  210  can be automatically locked from independent rotation. Accordingly, the upper unit is at least partially dependent on the orientation of the lower unit. 
     An additional feature will be described with reference to  FIG. 15 . As mentioned previously, because of the typical large geometry of the feeder unit, a large leverage advantage and torque can be applied to the upper unit  210 . This may inadvertently damage or break the lock, hinge or other related components. To overcome this, a lock override function is provided that yields to excessive force without causing any damage. The yield condition is enabled by spring  560 , which initially provides a preload force to hinder gear tooth cam out between pivot lock  540  and gear  335 . In particular, when excessive force F is applied to  210  when  220  is in the non-horizontal position, the gears  325  and  335  try to rotate against the restraining force applied by the interference of  540  with  335 . At some force level, the spring  560  will yield and allow the rotation lock  540  to disengage and then reengage the next tooth. Thus, during overriding there will be a noise of teeth skipping that may alert the user to desist in application of excessive force. Furthermore, exemplary overrides are automatically reset upon removal of the damaging force. Additionally, it is preferable that the override be inhibited when the lower scan unit  220  is in the substantially horizontal position. This ensures free pivoting of the upper device  210 . 
     A number of methods of accomplishing the lock and override can be used. One solution is to use opposing plates with a series of radial beveled “teeth” that are held in contact by spring loading one plate against the other. When sufficient rotation force is applied to the pivotal plate, it cams out of contact with the stationary plate, resulting in a desired override. However, this requires a linkage between a stationary frame and the pivoting structure of the hinge such that the plate engagement does not occur until the lower scan housing  220  is pivoted an elevated distance for actuation. 
     Another method eliminates the need for connections outside the hinge by using a pivoting mass internal to the hinge assembly  300  that gravitationally actuates the mechanism as the structure pivots upward. This is shown in  FIG. 15 . One way to create a lock and the gravity actuator is to use a wrap spring that grabs a centrally pivoting shaft but then allows an override function by slipping against the high friction as greater force is applied. The pivoting weight releases a slight wrap tension change necessary to allow free pivot motion of the feeder unit when the scanner unit is closed. This solution requires very tight tolerance control. 
     Another solution is to use a toggle and slide friction lock that similarly yields to sufficiently high force loads to accomplish the override. The toggle is brought into contact or held away from contact with the slider by the pivoting weight to engage or release the lock. This can be further refined by inclusion of a high force spring loading back up plate that limits slide force to provide a specific force window for the override slippage. 
     Ideally, the various locks and override structure are incorporated into the hinge itself, so that external linkages, manual release latches and catches that would otherwise interfere with operation of the device, such as copying or “original” document placement, can occur without obstruction. Thus, it is preferable that the various motion locks are internal to the hinge and neatly incorporated into an “envelope” formed from the various hinge component housings. 
     An exemplary hinge assembly  300  is of the detent and counterbalance type that provides detent, counterbalancing and motion/mass control functions as better shown in  FIG. 16 . Similar functionality can be provided in lower hinge assembly  400 . This functionality can be provided in many ways. In the illustrated embodiment using hinge assembly  300  from the  FIG. 11  embodiment, spring loading plunger  320  using spring  315  against profiled cam surface  350  provides the necessary detent and counterbalance functionality. Cam profile  350  may include a closed position  352 , a transition range  354 , a counterbalance range  356 , an auto open range  358 , and an open position  360  as shown. Detent positions  352  and  360  can be set at predetermined angular locations and have an overtravel profile contour  351  that requires a noticeably higher force to remove the hinge assembly from these first and second end positions. These detent positions  352 ,  360  thus cause a condition where additional motion or overtravel can occur only by supplying a noticeably higher force. Overtravel force and travel range are intentionally incorporated and are exclusive of system flexure against a “hard” stop. Moreover, the profile preferably tightly constrains the hinge assembly in these positions. This may be achieved, for example, by providing a cam profile with a detent, a condition where additional motion or overtravel can occur only by supplying a noticeably higher force. 
     The intermediate position defined as the counterbalance range  356  is preferably provided with a cam profile and spring force that counterbalances the weight and leverage of the upper unit so that the unit can be left at an intermediate position without requiring a user force for retention. That is, the hinge assembly is designed at this position to approximately neutralize the force of gravity so the unit will remain stationary if there are no external stabilizing or motion forces. 
     It is further preferable to provide the auto open range  358  with a cam profile complementary to the spring force that provides an urging force to bias the upper pivoting unit toward the fully open position  360 . This provides an operator with tactile feedback that assists in positioning of the pivoting unit to the full intended open position  360 . The urging force does not have to be so strong that it achieves full open functionality without further user assistance, but results in at least a lessening of the urging force needed by the operator to open the unit. 
     The numeric range for the various positions can be determined based on user preference and device-specific constraints. All functions or any number of combinations of functions described may be employed in the hinge or omitted depending on the mass and desired function of the units involved. 
     While aspects of the invention have been described in conjunction with the exemplary embodiments outlined above, various alternatives, modifications, variations, and/or improvements, whether known or that are, or may be, presently unforeseen, may become apparent. Accordingly, the exemplary embodiments of the invention as set forth above are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention. Therefore, the systems and methods described are intended to embrace all known, or later-developed, alternatives, modifications, variations, and/or improvements.