Patent Publication Number: US-7219935-B2

Title: Latch apparatus and method

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This patent application claims priority to U.S. Provisional Patent Application No. 60/260,420 filed on Jan. 9, 2001, the entirety of which is incorporated herein by reference. 
   FIELD OF THE INVENTION 
   The present invention relates to latches and latching methods, and more particularly to devices and methods for controlling a latch in its locked and unlocked states and for switching a latch between such states. 
   BACKGROUND OF THE INVENTION 
   Conventional latches are used to restrain the movement of one member or element with respect to another. For example, conventional door latches restrain the movement of a door with respect to a surrounding door frame. The function of such latches is to hold the door secure within the door frame until the latch is released and the door is free to open. Existing latches typically have mechanical connections linking the latch to actuation elements such as handles which can be actuated by a user to release the latch. Movement of the actuation elements is transferred through the mechanical connections and (if not locked) can cause the latch to release. The mechanical connections can be one or more rods, cables, or other suitable elements or devices. Although the following discussion is with reference to door latches (e.g., especially for vehicle doors) for purposes of example and discussion only, the background information and the disclosure of the present invention provided applies equally to a wide variety of latches used in other applications. 
   Most current vehicle door latches contain a restraint mechanism for preventing the release of the latch without proper authorization. When in a locked state, the restraint mechanism blocks or impedes the mechanical connection between a user-operable handle (or other door opening device) and a latch release mechanism, thereby locking the door. Many conventional door latches also have two or more lock states, such as unlocked, locked, child locked, and dead locked states. Inputs to the latch for controlling the lock states of the latch can be mechanical, electrical, or parallel mechanical and electrical inputs. For example, by the turn of a user&#39;s key, a cylinder lock can mechanically move the restraint mechanism, thereby unlocking the latch. As another example, cable or rod elements connecting a door lock to the restraint mechanism can be controlled by one or more electrical power actuators. These actuators, sometimes called “power locks” can use electrical motors or solenoids as the force generator to change between locked and unlocked states. 
   An important issue with regard to the design of latch assemblies is the desirability of a latch assembly to operate smoothly. Unless friction is employed to retain one or more elements in desired positions in the latch assembly, low-friction contact (such as contact between rotatably-connected elements) is preferred. In addition, latch assembly designs in which part wear is reduced or eliminated is highly desirable. These latch assembly design considerations significantly limit the number of viable solutions for a number of latch assembly design problems described below. 
   In most conventional latch designs, one or more elements are moved to release a retaining element holding the latch in a latched position. For example, a pawl can be movable to release a ratchet holding the striker of the latch. The pawl (or other movable element used to hold the ratchet in a latched position) can be moved in many different manners, such as by being rotated, pushed, pulled, shifted, and the like. Typically, one or more elements such as levers are movable by actuation of a handle or other latch assembly input to move the pawl. These pawl-moving elements can be connected directly to the pawl or can otherwise be moved to exert motive force upon the pawl. In either case, preventing inadvertent movement of the pawl by these pawl-moving elements is another important design consideration, and can be accomplished by controlling the position and mobility of the pawl-moving elements in the latch assembly. Such inadvertent movement can be caused in some conventional latch assemblies by employing pawl-moving elements that have a mass close to the pawl and that can react to shock or severe vibration to impart force upon the pawl, by severe impact upon the latch (such as experienced in a vehicle collision or rollover), and by other manners. 
   Because many pawl-moving elements have locked and unlocked states as described above, such elements must often be moved or movable in different manners corresponding to the locked and unlocked states. Such movement can limit the ability to fully secure and control the pawl-moving element within the latch assembly (both highly desirable features of pawl-moving elements). Therefore, the possible manners in which pawl-moving elements can be connected and move within latch assemblies is often significantly limited. 
   It is possible to add structure and elements to conventional door latch designs in order to address the above-noted problems and to take into account the latch assembly design considerations described above. However, such additional structure and elements are likely to increase latch complexity. Increased latch complexity also increases assembly and repair cost. Accordingly, the reasonable door latch design alternatives available to address the above-noted problems and design considerations of conventional door latches are significantly limited. 
   Problems of latch weight and size are related to the problem of latch complexity. The inclusion of more elements and more complex mechanisms within the latch generally undesirably increases the size and weight of the latch. In virtually all vehicle applications, weight and size of any component is a concern. Therefore, many latch designs employing additional structure and elements to address the above-noted problems and to take into account the design considerations described above do so at an unacceptable cost of increased latch weight and size. 
   Regardless of the mechanism employed to change the locked state of a latch assembly (to disable or enable a mechanical or electrical input to the latch assembly), another problem common to the vast majority of conventional door latches relates to the inability of such door latches to properly respond to multiple inputs at a given time. A well-recognized example of this problem is the inability of most conventional door latches to properly respond to a user unlocking the door latch while the door handle is partially or fully actuated. While this problem can exist for door latches that are not powered, it is particularly problematic in powered latches. For example, a user of a keyless entry system can push a button on a key fob, enter an access code on a door keypad, or otherwise transmit a signal (by wire or wirelessly) to a controller in the vehicle that in turn sends a signal to power unlock a handle input to the latch. In conventional power latches, an amount of time is required for this process to take place. During this time, a user may attempt to unlatch the latch by actuating the handle input. Because the latch has not yet been unlocked, such actuation does nothing—even after the latch has been powered to its unlocked state while the handle input is in a partially or fully actuated position. The user must release the handle, transmit another unlocking signal to power unlock the handle, and then re-actuate the handle to unlatch the latch. In other words, to unlatch a conventional latch, actuation of the handle input must occur after the handle input has been placed in its unlocked state. Partial or full actuation of the handle input before this time will not unlatch the latch and will require the user to release and re-actuate the handle input. 
   This shortcoming of conventional door latches exists for powered and fully manual door latches alike. In addition to requiring the user to re-actuate an input to unlatch the unlocked latch, this problem can even prevent the latch from changing between its locked and unlocked states. In such a case, the user is required to unlock the latch assembly again (re-transmit a signal to the latch assembly or manually unlock the latch assembly again as described above) after the handle input has been released. Any of the results just described represent an annoying attribute of conventional latch assembly designs. In this and other examples, a conventional latch assembly is unable to respond to actuation of more than one input at a time, or is only responsive to one of two inputs actuated simultaneously or closely in time. 
   In light of the problems and limitations of the prior art described above, a need exists for a latch assembly that is relatively simple in construction, lightweight, reliable, and easy to assemble and maintain, operates smoothly and efficiently with minimal friction and wear, has pawl-moving elements having improved control and stability, is preferably able to properly respond to an unlocking/locking input and to an latching/unlatching input received simultaneously or closely in time, and does so with minimal to no additional latch assembly elements and structure. Each preferred embodiment of the present invention achieves one or more of these results. 
   SUMMARY OF THE INVENTION 
   Some preferred embodiments of the present invention employ a pawl releasably engagable with a ratchet latching the door in place, a user-manipulatable handle, a lever movable between an unlocked position in which actuation of the lever by the handle generates sufficient pawl movement to release the ratchet and a locked position in which actuation of the lever by the handle does not generate sufficient pawl movement to release the ratchet, and a locking and unlocking mechanism coupled to the lever for moving the lever between its unlocked and locked positions. In some highly preferred embodiments, the locking and unlocking mechanism is an over-center device capable of moving the lever between its unlocked and locked positions. Also, the lever in some highly preferred embodiments is pivotable about the same or substantially the same location with respect to the lever in the locked and unlocked positions of the lever. In either case and in still other embodiments, the lever can be moved (e.g., by the locking and unlocking mechanism) between a locked position in which the mass of the lever or portion thereof is removed a distance from the pawl and an unlocked position in which the mass of the lever or portion thereof is moved closer to the pawl. 
   A significant amount of control over the lever is possible when the lever is pivotable in the locked and unlocked positions about the same or substantially the same location with respect to the lever. This location can be (and in some embodiments is) a location where the locking and unlocking mechanism is attached to the lever. By moving this point about which the lever pivots in its various states, the lever can be reliably moved to different locations with respect to the pawl while maintaining a degree of control over lever orientation and action. The pivot point of the lever can be in the same place or substantially the same place with respect to the lever in all positions of the lever in the latch assembly or in only a locked position and an unlocked position of the lever in the latch assembly. Also, the lever can be moved between its locked and unlocked positions by translating and/or rotating the lever or by moving the lever in any other manner desired. 
   In some embodiments of the present invention, additional control over the lever used to move the pawl is achieved by use of an over-center locking and unlocking mechanism. Specifically, an over-center device can be used to move the lever between its locked and unlocked positions. The over-center device has at least two stable positions separated by an unstable “center” position. Therefore, when the over-center device is actuated to one side of the center position, the lever connected thereto remains on that side until the over-center device is actuated to the opposite side of the center position. In this manner, the lever can be placed by the over-center device in a locked state in which the lever is in one position with respect to the pawl and in an unlocked state in which the lever is in another position with respect to the pawl. In some embodiments, the over-center device is biased away from the center position in either or both directions, thereby further retaining the lever in its locked or unlocked state until the over-center device is actuated again. In other embodiments, the over-center device is not biased away from the center position in one or both directions. In such embodiments, actuation of the lever can draw the over-center device further away from the center position, thereby ensuring that the lever stays in the locked or unlocked state to which it has already been moved. 
   The over-center device can take a number of different forms. For example, the over-center device can be or include two elements that are rotatably coupled together at a first pivot point. One of the two elements can be mounted for pivotal movement about a second pivot point and the other element can be pivotably connected at a third pivot point to the lever used to move the pawl. By rotating either element of the over-center device, the other element also rotates and causes the lever to move with respect to the pawl. In some embodiments, the center position of such an over-center device is defined by a line passing through the second and third pivot points, whereby the position of the first pivot with respect to either side of the line determines whether the lever is in a locked or unlocked state. 
   The two elements in the over-center device just described can take a number of different forms, such as an elongated bar pivotably coupled at one end to the lever and at another end to an edge of a disc that is rotatable about its axis, two links connected in a similar manner, and the like. Other types of over-center devices can be employed, such as an over-center device having a first element connected to or capable of moving the pawl and biased against an inclined surface of a second element. The two stable positions of the over-center device are defined by the first element located at the “top” and “bottom” of the inclined surfaces of the second element, respectively (whereby the first element can be retained in a recess, at plateau, on a step, or by another feature located at the top of the inclined surface of the second element). In yet another type of over-center device, a first element is connected to or is otherwise capable of moving the pawl and is biased against the surface of a rotatable second element. The surface is preferably eccentric with respect to the rotational axis of the second element. Therefore, the two stable positions of the over-center device are defined by the first element located at two different rotational positions of the second element (e.g., rotated toward the first element and rotated away from the first element). Still other types of over-center devices can be used as desired. 
   Although some embodiments of the present invention employ an over-center device with a lever that is pivotable about substantially the same position with respect to the lever in the locked and unlocked states thereof, it should be noted that any other locking and unlocking mechanism can be employed to move the lever as described above. For example, the locking and unlocking mechanism can be a solenoid, hydraulic or pneumatic cylinder, or any other type of actuator. Also, the over-center device can be employed to position a lever that is pivotable about different points with respect to the lever in the locked and unlocked states thereof. 
   It is desirable in some applications to remove the lever (used to move the pawl) a distance away from the pawl when the lever is in a locked state. More specifically, the mass of the lever that is located nearest to the pawl when the lever is in its unlocked state is preferably removed a distance from the pawl when the lever is in its locked state. In this manner, the opportunity for the lever to be forced toward and against the pawl when the lever is in its locked state is further reduced. For example, protection is increased against lever movement against the pawl causing pawl release as a result of shock, impact, or severe vibration of the latch assembly, such as from a vehicle collision or rollover. Preferably, an over-center device coupled to the lever can be used to move the mass of the lever toward and away from the pawl in the unlocked and locked states of the lever, respectively. However, any locking and unlocking mechanism can be employed to move the lever for this purpose. 
   In some preferred embodiments of the present invention, the latch assembly is capable of properly responding to unlatching and unlocking inputs received at the same time or closely in time. In other words, when the lever used to move the pawl is actuated before or while a locking and unlocking mechanism is placed in its unlocked state, the latch assembly properly responds by unlatching the latch upon movement of the locking and unlocking mechanism to the unlocked state. In one preferred application involving a car door latch capable of being unlocked via a remote keyless entry system, the user can partially or fully actuate the door handle prior to unlocking the door or while the door is being unlocked (e.g., while the keyless entry system is still processing the request to unlock the latch assembly, during movement of the locking and unlocking mechanism to its unlocked state, and the like). The latch assembly responds by unlatching the latch when the latch assembly is finally unlocked, and does so without requiring the user to release and re-actuate the door handle. Although the other embodiments of the present invention described above can operate without this feature, such latch assembly embodiments preferably have this capability. 
   More information and a better understanding of the present invention can be achieved by reference to the following drawings and detailed description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention is further described with reference to the accompanying drawings, which show preferred embodiments of the present invention. However, it should be noted that the invention as disclosed in the accompanying drawings is illustrated by way of example only. The various elements and combinations of elements described below and illustrated in the drawings can be arranged and organized differently to result in embodiments which are still within the spirit and scope of the present invention. 
     In the drawings, wherein like reference numerals indicate like parts: 
       FIG. 1  is a perspective view of a latch assembly according to a preferred embodiment of the present invention, shown with an outside door handle mechanism of the latch assembly in a locked state and in an actuated position; 
       FIG. 2  is an elevational view of the ratchet and pawl mechanism in the latch assembly of  FIG. 1 ; 
       FIG. 3  is an elevational detail view of the latch assembly illustrated in  FIG. 1 , shown with the outside door handle mechanism in an unlocked and unactuated state; 
       FIG. 4  is an elevational detail view of the latch assembly illustrated in  FIG. 1 , shown with the outside door handle mechanism in an unlocked and actuated state; 
       FIG. 5  is an elevational detail view of the latch assembly illustrated in  FIG. 1 , shown with the outside door handle mechanism in a locked and unactuated state; 
       FIG. 6  is an elevational detail view of the latch assembly illustrated in  FIG. 1 , shown with the outside door handle mechanism in a locked and actuated state; 
       FIG. 7  is an elevational detail view of the latch assembly illustrated in  FIG. 1 , shown with the outside door handle mechanism in a center position; 
       FIG. 8  is an elevational view of a door handle mechanism according to a second preferred embodiment of the present invention; 
       FIG. 9  is an elevational view of a door handle mechanism according to a third preferred embodiment of the present invention; 
       FIG. 10  is an elevational view of a door handle mechanism according to a fourth preferred embodiment of the present invention; 
       FIG. 11  is an elevational view of a door handle mechanism according to a fifth preferred embodiment of the present invention, shown with the door handle mechanism in an unlocked and unactuated state; 
       FIG. 12  is an elevational view of the door handle mechanism illustrated in  FIG. 11 , shown with the door handle mechanism in an unlocked and actuated state; 
       FIG. 13  is an elevational view of the door handle mechanism illustrated in  FIG. 11 , shown with the door handle mechanism in a locked and unactuated state; 
       FIG. 14  is an elevational view of the door handle mechanism illustrated in  FIG. 11 , shown with the door handle mechanism in a locked and actuated state; 
       FIG. 15  is an elevational view of a door handle mechanism according to a sixth preferred embodiment of the present invention; 
       FIG. 16  is an elevational view of a door handle mechanism according to a seventh preferred embodiment of the present invention, shown with the door handle mechanism in a locked and unactuated state; 
       FIG. 17  is an elevational view of the door handle mechanism illustrated in  FIG. 16 , shown with the door handle mechanism in a locked and actuated state; 
       FIG. 18  is an elevational view of the door handle mechanism illustrated in  FIG. 16 , shown with the door handle mechanism in an unlocked and unactuated state; and 
       FIG. 19  is an elevational view of the door handle mechanism illustrated in  FIG. 16 , shown with the door handle mechanism in an unlocked and actuated state; 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   An example of a latch assembly according to a preferred embodiment of the present invention is illustrated in  FIG. 1 . Only that portion of the latch assembly necessary for an understanding of the present invention is shown in  FIG. 1 . Accordingly, a number of latch assembly elements are not shown in  FIG. 1  for purposes of clarity. The latch assembly of the present invention (indicated generally at  10  in  FIG. 1 ) is described hereinafter with reference to use in a vehicle door application. However, it should be noted that the latch assembly  10  can instead be used in many other applications. The present invention can be used in any application in which it is desirable to releasably secure one body to another. Such applications can be non-automotive and need not involve doors. 
   In most vehicle door latch applications, a latch will have a connection to an inside door handle, an outside door handle, an inside lock, and possibly an outside lock (e.g., usually for front doors of a vehicle). Each of these connections represents an input to the latch. Typically, latch inputs are operable either to generate latch release or to enable or disable such an input. Inputs for generating latch release usually run from a user-manipulatable device such as a lever located inside or outside of the vehicle. Inputs for enabling and disabling these latch release inputs can also run from a user-manipulatable device inside or outside of the vehicle, such as a lock cylinder, a sill button, an electrical controller or user-operable electronic device such as a keypad or remote access electronic system connected to the latch assembly, and the like. Regardless of what mechanical or electrical controls are employed to control and trigger latching, unlatching, and latch input enabling and disabling, virtually every vehicle latch has a mechanism for ultimately performing these functions. 
   The latch assembly in the illustrated preferred embodiment has two latch inputs for generating latch release (i.e., “latch release inputs”) and two latch inputs for enabling and disabling these latch release inputs (i.e., “locking and unlocking inputs”). Other latch assemblies embodying the present invention can have fewer or greater numbers of latch release inputs and locking and unlocking inputs. With particular reference to  FIG. 1 , one of the latch release assemblies  24  is at least partially defined by a control lever  12  pivotably mounted within the latch assembly housing  14  and an actuating lever (not shown) pivotably mounted to actuate the control lever  12  about a pivot  18 . Another latch release assembly  26  includes another control lever  20  and an actuating lever (also not shown) pivotably mounted to actuate the control lever  20 . As will be described in greater detail below, actuation of an actuating lever when the corresponding control lever  12 ,  20  is in its unlocked state will unlatch the latch assembly  10 . Actuation of an actuating lever when the corresponding control lever  12 ,  20  is in its locked state will not unlatch the latch assembly  10 . 
   With reference to  FIG. 2 , the latch assembly  10  preferably has a ratchet and pawl mechanism to latch a door in its closed position. In this mechanism, the ratchet  30  and striker (not shown) releasably engage one another, and can be mounted in any conventional manner on the door and its respective door jam for movement relative to one another. For example, the striker can be mounted upon a door jam, while the latch assembly  10  and ratchet  30  can be mounted on a vehicle door movable to a closed position in which the striker enters an aperture  32  in the ratchet  30  and is trapped therein upon resulting movement of the ratchet  30 . Alternatively, the striker can be mounted upon the vehicle door, while the latch assembly  10  and ratchet  30  are mounted upon the door jam. In either case, the ratchet  30  is preferably movable between a latched position in which a striker is trapped in the ratchet aperture  32  and an unlatched position in which the striker is free to exit the ratchet aperture  32 . This ratchet movement can be (and preferably is) rotational, whereby the ratchet  30  is mounted to rotate about a pivot. However, other forms of ratchet movement are possible. To capture the striker, the ratchet  30  usually cooperates with the latch assembly housing  14  so that the striker is captured by the walls of the ratchet aperture  32  and by a wall or other portion of the latch assembly housing  14  when the ratchet  30  is in its latched position. It should be noted that other forms of striker capture are also possible, and need not necessarily employ purely rotational ratchet movement or any type of rotational ratchet movement. Also, the shape of the ratchet and striker can vary significantly while still performing the function of releasably capturing the striker via movement of the ratchet  30  when engaged therewith. One having ordinary skill in the art will recognize that many different striker and ratchet designs and arrangements are possible. 
   Regardless of how the ratchet  30  moves and how it captures a striker, the pawl  28  preferably cooperates with the ratchet  30  to hold the ratchet  30  in a particular position or state. The ratchet  30  is most preferably releasably engagable by the pawl  28  to hold the ratchet  30  in its latched state. Although such an arrangement is described hereinafter, it should be noted that the pawl  28  can be releasably engagable with the ratchet  30  to hold the ratchet  30  in its unlatched state in other latch embodiments. One pawl design is shown in  FIG. 2  by way of example only. The pawl  28  shown in  FIGS. 1 and 2  can take a number of different shapes. In addition, one having ordinary skill in the art will appreciate that numerous mechanisms for releasably capturing a striker exist in the art and can be employed in conjunction with the present invention as described in greater detail below. 
   With continued reference to  FIG. 2 , the pawl  28  is pivotable into and out of engagement with the ratchet  30 , and has an engagement portion  34  that obstructs movement of the ratchet  30  to its unlatched position by engagement with a step  36  on the ratchet  30 . In another example, the pawl  28  is pivotable into and out of engagement with a lip, ledge, peg, abutment, boss, tooth, or other element or feature of the ratchet  30 . Because the ratchet  30  is preferably spring-loaded toward its unlatched position, disengagement of the pawl  28  from the ratchet  30  permits the ratchet  30  to move and to thereby release a striker (not shown). Rotation of the pawl  28  therefore generates striker release. Like the ratchet  30 , the pawl  28  can take any form capable of releasably engaging with the ratchet  30  to selectively limit ratchet movement. 
   Although other conventional forms of pawl movement (e.g., translation or a combination of translation and rotation) to engage and disengage the ratchet  30  are possible and fall within the spirit and scope of the present invention, a rotatable pawl  28  is most preferred. Accordingly, and with reference to the illustrated preferred embodiments of the present invention, rotation of the pawl  28  is preferably performed to disengage the ratchet  30  and thereby to unlatch the latch assembly  10 . 
   Because the pawl  28  functions to retain the ratchet  30  in a latched state until the pawl  28  is actuated to its unlatched position, the latch assembly  10  is preferably controlled by control of pawl movement and position in the latch assembly  10 . To this end, the control levers  12 ,  20  can be actuated to move the pawl  28 . Any number of control levers  12 ,  20  can be employed for this purpose, each control lever  12 ,  20  being connected to one or more latch release inputs (not shown). In some highly preferred embodiments, each control lever  12 ,  20  is movable in at least two different manners. In at least one manner, the control lever  12 ,  20  can move the pawl  28  to release the ratchet  30  (thereby unlatching the latch  10 ). A control lever  12 ,  20  movable in this manner is therefore in an unlocked state. In at least one other manner, the control lever  12 ,  20  cannot move the pawl  28  to release the ratchet  30 , or at least cannot move the pawl  28  sufficiently to release the ratchet  30 . A control lever  12 ,  20  movable in this manner is therefore in a locked state. 
   In the preferred embodiment illustrated in  FIG. 1 , the control levers  12 ,  20  are moved by actuation of respective actuating levers (not shown). The actuating levers can be translatable or rotatable in any manner to exert actuating force against the control levers  12 ,  20  in order to move the control levers  12 ,  20  when a corresponding door handle (or other latch release input) is actuated. Also, the actuating levers can be any shape desired. By way of example only, the actuating levers can be elongated, L or V-shaped, polygonal, round, or can have any other shape that can be connected to pivot or shift when actuated to exert actuating force upon a corresponding control lever  12 ,  20 . The actuating levers can be connected to the control levers  12 ,  20 , such as by a pinned connection, a ball joint, a hinge, a spring, and the like, or can interact with the control levers  12 ,  20  through a camming, pushing, or other motion. 
   One example of the manner in which the control levers  12 ,  20  can be connected to actuating levers is illustrated in FIGS.  1  and  3 – 7 . Specifically, the control lever  12  illustrated on the bottom of  FIG. 1  is preferably rotatably connected to an actuating lever (not shown) by a pin-and-aperture connection. The actuating lever preferably has a pin, post, or other extension received within an aperture  40  in the control lever  12 . The locations of the pin and aperture  40  can be reversed in alternative embodiments. 
   In the illustrated preferred embodiment, the control lever  12  is connected to an outside door handle by the actuating lever (not shown). Force from the outside door handle can be transmitted to the actuating lever and thereby to the control lever  12  by any number of different elements and connections. For example, one or more rods, cables, wires, levers, or other elements can extend from the door handle to the actuating lever for this purpose. Alternatively, the actuating lever itself can be connected directly to the door handle for actuation thereby. 
   The inside and outside door handles connected to the latch assembly  10  can preferably be locked and unlocked by placing the latch release assemblies  24 ,  26  in their locked and unlocked states, respectively. In other latch assembly embodiments, not all of the latch release inputs to the latch assembly  10  have this capability of being locked and unlocked. 
   For purposes of describing the present invention, the latch release assembly  24  for the outside door handle of the illustrated preferred embodiment in  FIG. 1  will be described in greater detail below. However, the following description applies equally to latch release assemblies directly or indirectly connected to other manual and automatic actuation devices (i.e., to devices other than door handles) and even to latch assemblies not associated with a door. In addition, although in the illustrated preferred embodiment the present invention is employed only for the outside door handle latch release assembly  24 , any different or additional latch release assembly can employ the principles of the present invention (e.g., a latch release assembly for an inside door handle, latch release assemblies for both inside and outside door handles, and the like). Reference below to the outside door handle and the connection of the latch release assembly  24  thereto is therefore made by way of example only. In addition, each of the embodiments illustrated and described herein can have any number of latch release assemblies  24  for connection to any number of handles or other latch release inputs. 
   A number of elements which are likely to be found in a latch in conjunction with the latch assembly of the present invention are not essential for the present invention and are not therefore described further herein or shown in  FIGS. 1–7 . For example, although not necessary for the present invention, the latch assemblies of the present invention can be at least partially enclosed within a cover or outer housing (not shown). As another example, in some embodiments, the latch release assemblies  24 ,  26 , pawl  28 , and ratchet  30  are biased by springs (also not shown) in any conventional manner toward respective positions within the latch assembly  10  and have one or more stops, walls, or surfaces (also not shown) limiting the range of motion of these elements. 
   In the embodiment of the present invention illustrated in  FIGS. 1–7 , the pawl  28  is mounted for pivotal movement about a pawl pivot  42 . The pawl pivot  42  can be an extension of the pawl  28 , a pivot attached to the pawl  28  in any conventional manner (e.g., by a threaded fastener, by welding, brazing, adhesive, and the like), or can extend from or be otherwise connected to the housing  14  of the latch assembly  10 . Therefore, by rotating the pawl  28  about the pawl pivot  42 , the pawl  28  can be rotated to engage or disengage the ratchet  30  as described above. 
   The pawl  28  can be rotated by the control lever  12  in a number of different manners, such as by camming contact between surfaces of the pawl  28  and control lever  12 , by an articulated joint between the pawl  28  and the control lever  12 , by a pin on the pawl  28  or lever  12  received within an aperture in the lever  12  or pawl  28 , respectively, and the like. By way of example only, the pawl  28  in the illustrated preferred embodiment has a post  44  against which the control lever  12  can push to rotate the pawl  28  about its pivot  42 . In other embodiments, the control lever  12  can act against the pawl post  44  to move the pawl  28  in other manners (e.g., translation or a combination of translation and rotation) depending at least partially upon the manner in which the pawl  28  is mounted in the latch assembly  10 . Also, one having ordinary skill in the art will appreciate that the control lever  12  can push or pull against other surfaces of the pawl  28  to generate movement thereof, such as against one or more edge surfaces of the pawl  28 , interior surfaces of an aperture in the pawl  28 , and the like. 
   Depending at least partially upon whether the control lever  12  is connected to the pawl  28  and upon which portion of the control lever  12  acts upon the pawl  28 , motive force (i.e., force generating motion of an element) can be imparted to the pawl  28  by any interior or exterior surface of the control lever  12 . For example, the outside handle control lever  12  in the latch assembly  10  illustrated in  FIGS. 1–7  is connected to the pawl  28  by the pawl post  44  extending through an aperture  46  in the outside handle control lever  12  (see  FIGS. 3–7 ). Therefore, actuation of the outside handle control lever  12  in its unlocked state (described below) causes an interior surface of the control lever aperture  46  to push against the pawl post  44  and to move the pawl  28 . In some preferred embodiments of the present invention, the control lever aperture  46  is elongated or is otherwise shaped to permit lost motion of the pawl post  44  therein in at least one of the positions of the control lever  12 . 
   Other control lever surfaces can push or pull the pawl post  44  or any other portion of the pawl  28  for generating motion of the pawl  28 . By way of example only, the pawl post  44  can be pushed by an outer peripheral surface of the control lever  12 . As another example, a pin, boss, or other extension of the control lever  12  can extend to a position adjacent to an edge of the pawl  28  for pushing the pawl  28  when the control lever  12  is actuated. This edge of the pawl  28  can be an outer peripheral edge or can be an edge of an aperture in the pawl  28 . As yet another example, the pawl  28  and control lever  12  can be located in substantially the same plane so that when the control lever  12  is actuated in its unlocked state, a peripheral edge of the control lever  12  is brought into contact with a peripheral edge of the pawl  28  to move the pawl  28 . Still other manners of transferring motive force from the control lever  12  to the pawl  28  are possible, each of which falls within the spirit and scope of the present invention. 
   As mentioned above, the control lever  12  has locked and unlocked states. In its locked state, the control lever  12  is incapable of moving the pawl  28  or is at least incapable of moving the pawl  28  sufficiently to release the ratchet  30  and to thereby unlatch the latch  10 . In its unlocked state, the control lever  12  can move the pawl  28  to release the ratchet  30  and thereby unlatch the latch  10 . A significant advantage of the latch assembly  10  illustrated in  FIGS. 1–7  is that the control lever  12  is well controlled within the latch assembly  10  despite the fact that the control lever  12  can be moved through different ranges of positions in different locked and unlocked states. This is due at least in part to the manner in which the control lever  12  pivots in both states. In particular, the control lever  12  preferably has a pivot point that is the same in both the locked and unlocked states of the control lever  12 . This pivot point can be located on or off of the control lever, but is preferably located in the same or substantially the same position with respect to the control lever  12  in both states of the control lever  12 . 
   In other words, even though the control lever  12  can be moved to different positions in the latch assembly  10 , the control lever  12  preferably pivots about the same or substantially the same point with respect to the control lever  12 . The control provided by such control lever movement is superior to other latch assembly designs in which the control lever pivots about different points with respect to the control lever in its locked and unlocked states. In many preferred embodiments of the present invention, the control lever  12  pivots about the point at which a locking and unlocking mechanism is connected to the control lever  12 . The locking and unlocking mechanism can be configured to orient the control lever  12  in its locked and unlocked states. This provides a significant amount of control over the control lever  12  regardless of whether the control lever  12  is in its locked or unlocked state and regardless of the position of the control lever  12 . 
   The locking and unlocking mechanism in the various embodiments of present invention is an actuator or defines part of an actuator capable of moving the control lever  12  with respect to the pawl  28 . A number of different locking and unlocking mechanisms can be employed to move the control lever  12  to different positions in the latch assembly  10  while still enabling the control lever  12  to pivot about the same or substantially the same pivot point with respect to the control lever  12 . One such locking and unlocking mechanism is illustrated in FIGS.  1  and  3 – 7 , and is indicated generally at  48 . The locking and unlocking mechanism  48  can define or be part of an actuator capable of moving the control lever  12 . The locking and unlocking mechanism  48  preferably has a first element  50  connected to a second element  52  which is mounted for rotation about an axis  54 . In some preferred embodiments, the first element  50  is movable by the second element  52  between locked and unlocked positions with respect to the control lever  12 . 
   The first element  50  is preferably a lever having an elongated shape as best shown in  FIGS. 3–7 , but can take any other shape desired. The first element  50  can be connected to the control lever  12  by the control lever pivot  18 , which in one embodiment is a pin  56  received within apertures  58 ,  60  in the first element  50  and control lever  12 , respectively. The control lever pivot  18  preferably permits relative rotation of the first element  50  with respect to the control lever  12 . The control lever pivot  18  can be integral with the first element  50  or the control lever  12  or can be attached to the first element  50  or the control lever  12  in any conventional manner (such as by being press-fit, welded, brazed, glued, and the like). Alternatively, the control lever pivot  18  can be retained in apertures in the first element  50  and in the control lever  12  by one or more cotter pins, by a nut received on a threaded end of a pin  56 , or by one or more other conventional fasteners. Other manners of pivotably connecting the first element  50  to the control lever  12  are possible, such as by a ball-and-socket joint, a hinge connection, and the like, each one of which falls within the spirit and scope of the present invention. 
   Either or both apertures  58 ,  60  in the first element  50  and control lever  12  of the illustrated preferred embodiment can be larger than the pin  56  to permit lost motion of the first element  50  with respect to the control lever  12 . More preferably however, the pin  56  is similar in shape and size to both apertures  58 ,  60 . 
   The first element  50  is preferably connected to the second element  52  at a distance from the axis of rotation  54  of the second element  52 . Although not required, the first element  50  is rotatably connected to the second element  52  in any conventional manner, such as by a pivot on the first or second element  50 ,  52  received within an aperture in the second or first element  52 ,  50 , respectively. For example, the first element  50  of the embodiment shown in  FIGS. 1–7  preferably has an elongated aperture  62  in which a pivot post  64  is rotatably received. Still other manners of rotatable connection are possible and would be recognized by those of ordinary skill in the art. 
   The second element  52  can also take any shape desired, and is shown as a generally round, disc-shaped element in FIGS.  1  and  2 – 7  only by way of example and illustration. The second element  52  is preferably rotatable in one direction to a position or range of positions corresponding to an unlocked state of the locking and unlocking mechanism  48  and in another direction to a position or range of positions corresponding to a locked state of the locking and unlocking mechanism  48 . In the illustrated preferred embodiment of  FIGS. 1–7 , the second element  52  is capable of only partial rotation in both directions. 
   With reference to  FIGS. 3–7 , the locking and unlocking mechanism  48  can be operated to move the control lever  12  between different positions in the latch assembly  10 . These different positions define the locked and unlocked states of the control lever  12 . Although any element or mechanism capable of moving the control lever  12  between different positions can be employed, an over-center device is most preferred. As will now be described, the locking and unlocking mechanism  48  illustrated in FIGS.  1  and  2 – 7  is an over-center device. 
   The “center” of the “over-center” locking and unlocking mechanism  48  is a rotational position of the second element  52 . Specifically, this center is preferably the rotational position at which the axis of rotation  54  of the second element  52  is co-linear with the connection points of the first element  50  to the control lever  12  and second element  52  as shown in  FIG. 7 . This rotational position of the second element  52  is represented by the dotted line  66  on  FIGS. 3–7 . When the second element  52  is rotated in one direction away from this dotted line  66  (e.g., in the counter-clockwise direction with reference to  FIGS. 3–7 ), the locking and unlocking mechanism  48  is in a locked state. When the second element  52  is rotated in an opposite direction away from this dotted line  66  (e.g., in the clockwise direction with reference to  FIGS. 3–7 ), the locking and unlocking mechanism  48  is in an unlocked state. 
   In the illustrated preferred embodiment, the second element  52  has a limited rotational range in both directions defined by stops upon the pivot (not shown) about which the second element  52  rotates. In other preferred embodiments, rotation of the second element  52  is limited in either or both directions by one or more stops on the second element  52 , the pivot (not shown) upon which the second element  52  is mounted for rotation, and/or a wall of the latch assembly  10 . In any case, the first element  50  is movable to either side of a center orientation with respect to the second element  52  to result in different positions with respect to the control lever  12  (thereby resulting in different interaction with the control lever  12  when actuated). Rotational stops and their manner of operation are well known to those skilled in the art and are not therefore described further herein. 
   As alternatives to the use of stops on the second element pivot or stops contacting the second element pivot as described above, one having ordinary skill in the art will appreciate that rotation of the second element  52  can be limited in either or both directions in a number of different manners. By way of example only, one or more walls, posts, or other protrusions can extend from the second element  52  and can abut against and be stopped by one or more walls, posts, or other protrusions located adjacent to the second element  52 , movement of the first element  50  can be limited by stops extending from the latch assembly housing  14  (see  FIG. 1 ), a stop extending from the first or second elements  50 ,  52  can be received within and stopped by one or more ends of an aperture in the latch assembly housing  14 , an extension or other peripheral portion of the second element  52  can abut one or more stops on a wall of the latch assembly housing  14  or other adjacent latch assembly structure, or a stop extending from the first element  50  can be received within and stopped by an aperture in the second element  52  (and vice versa) or can abut against an edge, side, wall, or other portion of the second element  52  (and vice versa). In still other embodiments, biasing members such as conventional springs can be connected to either or both of the first and second elements  50 ,  52  and to the latch assembly housing  14  or other assembly structure to limit second element rotation. 
   The stops described above can take any shape and form desired, including without limitation walls, posts, pins, fingers, ribs, bumps, flanges, bosses, or other protrusions or extensions, and can be integral with or connected to the associated element in any manner. 
   In operation, the second element  52  can be rotated to either side of the center position  66 . Because the control lever  12  is connected to the second element  52  via the first element  50 , rotation of the second element  52  changes the position of the control lever  12  with respect to the pawl  28 . The control lever  12  can be moved in any direction or manner desired, depending at least partially on the manner in which the first element  50  is connected to the control lever  12  and where this connection is located on the control lever  12 . In the illustrated preferred embodiment for example, the control lever  12  is movable generally vertically when the second element  52  is rotated. More specifically, rotation of the second element  52  causes the control lever  12  to pivot about or near its right end as shown in FIGS.  1  and  3 – 7 . In this manner, the position of the control lever  12  is changed with respect to the pawl  28  as will now be described in greater detail. 
   When the second element  52  is rotated in a first direction past the center position  66  of the locking and unlocking mechanism  48  as shown in  FIG. 3  of the illustrated preferred embodiment, the second element  52  is stopped by a stop as described above. Preferably, the second element  52  is spring-biased in this direction toward a stable position as also described above. When the control lever  12  is actuated in this position (rotated counter-clockwise as viewed in  FIG. 4 ) the control lever  12  pivots about or near the control lever pivot  18  while the control lever  12  moves the pawl post  44  to release the pawl  28 . Therefore, rotation of the pivot post  64  to the right of the center position  66  in  FIGS. 3–7  defines the unlocked state of the control lever  12 . 
   When the second element  52  is rotated in a second direction opposite to the first direction and past the center position  66  of the locking and unlocking mechanism  48  as shown in  FIG. 5  of the illustrated preferred embodiment, the second element  52  is preferably again stopped by a stop as described above. The second element  52  can be spring-biased in this direction as also described above. Rotation of the second element  52  in this direction is preferably limited so that the control lever pivot  18  is located at a lower elevation (as viewed in  FIGS. 1–7 ) than when the second element  52  is fully rotated to its unlocked position described above. Therefore, when the control lever  12  is actuated in this position (rotated counter-clockwise as viewed in  FIG. 6 ) the control lever  12  pivots about or near the control lever pivot  18 . However, because the control lever  12  has been moved with respect to the pawl  28  by rotation of the second element  52 , the aperture  46  in the control lever  12  is not positioned to move the pawl post  44  to release the pawl  28 . Therefore, rotation of the pivot post  64  to the left of the center position  66  in  FIGS. 3–7  defines the locked state of the control lever  12 . 
   In some highly preferred embodiments, the first and second elements  50 ,  52  do not move or do not move significantly when the control lever  12  is actuated in either the locked state or the unlocked state of the locking and unlocking mechanism  48 . However, in other embodiments, both elements are free to move in their locked state and/or in their unlocked state when the control lever  12  is actuated. Therefore, in such alternative embodiments, rotation of the control lever  12  about the control lever pivot  18  in the locked or unlocked state is not necessarily exclusive (the control lever  12  can also pivot about a second point located a distance from the control lever pivot  18 ). 
   One having ordinary skill in the art will appreciate that the locked and unlocked positions described above can be reversed in other embodiments by changing the amount of second element rotation permitted in each direction past the center position  66 . 
   The second element  52  is therefore operable to move the first element  50  into and out of a position in which the control lever  12  is incapable of exerting motive force or exerts insufficient motive force to trigger pawl release. The locking and unlocking mechanism  48  preferably has at least one stable position on either side of the center position  66  and at least one unstable position therebetween (at the center position  66 ). In some preferred embodiments such as the illustrated preferred embodiment, the locking and unlocking mechanism  48  has a range of stable positions on either or both sides of the center position  66  and an unstable position therebetween. The ranges of positions to either side of the center position  66  are stable because actuation of the control lever  12  urges the second element  52  to rotate away from the unstable position  66 . In some highly preferred embodiments, these ranges of positions to either side of the center position  66  are also stable because the second element  52  is spring-biased toward stable positions on either side (and more preferably, both sides) of the center position  66 . 
   The unstable positions are preferably divided by the “over center” position coinciding with line  66  described above so that actuation of the control lever  12  draws the locking and unlocking mechanism  48  toward one or the other stable position if not already there (e.g., biased under spring force). Specifically, and with reference to  FIGS. 3–7 , tension placed upon the first element  50  by actuation of the control lever  12  exerts force upon the rotatable second element  52  in one rotational direction or the other away from the center position  66 . 
   It will be appreciated by one having ordinary skill in the art that the range of rotation of the second element  52  can vary significantly in different embodiments of the present invention. The amount of second element rotation in each direction past the center position of line  66  can also vary significantly. For example, the range of second element rotation in one direction past the line  66  can be any fraction of the range of second element rotation in an opposite direction past the line  66 , depending at least partially upon the relative positions of the first element  50 , second element  52 , and the control lever  12 . In the preferred embodiment illustrated in  FIGS. 1–7  for example, the second element  52  is preferably free to rotate clockwise from the center position  66  to the stable unlocked position shown in  FIGS. 3 and 4  until the pivot (not shown) upon which the second element  52  rotates is stopped as described above, and is preferably free to rotate through a larger range counter-clockwise from the center position  66  to the stable locked position shown in  FIGS. 5 and 6 . 
   As mentioned above, the locking and unlocking mechanism  48  illustrated in  FIGS. 1–7  is preferably biased toward one of two stable positions on either side of the center position  66  indicated by dotted line  66 . The locking and unlocking mechanism  48  can be biased toward a stable position in either direction, and more preferably is biased in both directions toward the stable end positions of the locking and unlocking mechanism  48 . To achieve this over-center biasing, the second element  52  is preferably provided with a conventional over-center spring (not shown) which can be connected to the second element  52  in any conventional manner, such as by being connected directly to a face of the second element  52  or to the pivot upon which the second element  52  is rotatably mounted. The over-center spring can be a torsion spring operable and connected in a conventional manner, although other types of springs directly or indirectly connected to bias rotation of the second element  52  can be used to perform the same function, such as leaf springs, coil springs, and the like. Over-center springs and their manner of connection and operation are well known to those skilled in the art and are not therefore described further herein. In other embodiments, two or more over-center springs can be used (such as one over-center spring for biasing the locking and unlocking mechanism  48  toward a stable position in one direction and another over-center spring for biasing the locking and unlocking mechanism  48  toward a stable position in an opposite direction). Such alternatives for a single over-center spring are well known to those skilled in the art for application in any of the embodiments of the present invention described herein. 
   A number of alternative biasing elements and devices can be used to bias the locking and unlocking mechanism  48  into the stable position(s) as described above. Specifically, one or more elastic bands can be coupled to the locking and unlocking mechanism  48  and to the latch assembly housing  14  or other structure adjacent to the locking and unlocking mechanism  48  for biasing the locking and unlocking mechanism  48  as described above. Alternatively, biasing force can be supplied by one or more sets of electro-magnets on the locking and unlocking mechanism  48  and on the latch assembly housing  14  or other structure adjacent to the locking and unlocking mechanism  48 . Any other type of biasing element or device can be employed in still other embodiments of the present invention, including without limitation frictionally engagable and disengagable elements, one or more air springs, and the like. 
   In the embodiment illustrated in  FIGS. 1–7 , the orientation of the first and second elements  50 ,  52  with respect to one another at least partially defines the location of the center position for the locking and unlocking mechanism  48 . The center position can also be defined by one or more biasing elements biasing the first and second elements toward either or both stable positions of the locking and unlocking mechanism  48  as described above. However, it should be noted that the rotational position of the second element  52  at which the biasing element(s) begin to exert force upon the locking and unlocking mechanism  48  toward the stable position(s) need not coincide with the center position  66  of the locking and unlocking mechanism  48 . In other words, the “center” position of the biasing elements need not coincide with the center position  66  of the locking and unlocking mechanism  48 . This is true not only of the first preferred embodiment illustrated in  FIGS. 1–7 , but also in the other embodiments of the present invention described in greater detail below. 
   By way of example only, and with reference to FIGS.  1  and  3 – 7  of the first preferred embodiment, a first spring can be coupled to the locking and unlocking mechanism  48  for urging rotation of the second element  52  in a clockwise direction to the stable position shown in  FIGS. 3 and 4 , and a second spring can be coupled to the locking and unlocking mechanism  48  for urging rotation of the second element  52  in a counter-clockwise direction to the stable position shown in  FIGS. 5 and 6 . These springs need not begin to exert force in their respective directions at the center line  66 . Instead, the first spring can begin to exert a clockwise force when the pivot post  64  is located a distance to the left of the center line  66  as viewed in  FIGS. 3–7 . Alternatively or in addition, the second spring can begin to exert a counter-clockwise force when the pivot post  64  is located a distance to the right of the center line  66  as viewed in  FIGS. 3–7 . These forces are preferably not sufficient to move the locking and unlocking mechanism  48  over the center line  66 , but can be desirable for smooth operation of the locking and unlocking mechanism  48 . It should also be noted that the biasing element(s) coupled to the locking and unlocking mechanism  48  need not exert force through the entire range of mechanism motion from the center line  66  to the respective stable positions. Instead, the biasing element(s) can exert such forces in any part of these ranges of motion as desired. 
   With combined reference to  FIGS. 3–7 , it can be seen that the control lever  12  is pivotable about the same (or substantially the same) point with respect to the control lever  12  in both locked and unlocked positions of the control lever  12 . In combination with the connection between the control lever  12  and the locking and unlocking mechanism  48 , this feature facilitates a significant amount of control over the control lever  12 , allowing the control lever  12  to be quickly, precisely, and repeatably positioned in a desired location with respect to the pawl  28 . Also, by moving the control lever  12  and its associated pivot point with respect to the pawl  28 , the control lever  12  can be removed from the pawl post  44  or other portion of the pawl  28  acted upon by the control lever  12  when the control lever  12  is in its locked state. Because the control lever  12  triggers pawl release, it is desirable in some applications to remove the control lever  12  or at least a part thereof a distance away from the pawl post  44 . Specifically, all or part of the control lever  12  can be removed from the pawl post  44  so that the pawl post  44  is less likely to be subject to forces from the control lever  12  as a result of shock, impact, extreme vibration (such as by impact to the latch assembly  10 , vehicle rollover, and the like), or tampering. It is therefore desirable in some embodiments of the present invention to remove the mass of the control lever  12  (or at least that portion of the control lever  12  that can act upon the pawl post  44 ) a distance from the pawl post  44 . A clearance between the control lever  12  and the pawl post  44  when the control lever  12  is in an unlocked state is therefore preferred in some embodiments of the present invention. 
   The pivot point about which the control lever  12  can pivot is located at an end of the control lever  12  in the illustrated preferred embodiment of  FIGS. 1–7 . However, the pivot point of the control lever  12  can be located anywhere along the control lever  12  or can even be located at a point off of the control lever  12 . 
   The locking and unlocking mechanism  48  illustrated in FIGS.  1  and  3 – 7  is only one of a number of devices and mechanisms that can be employed to move the control lever  12  with respect to the pawl  28 . For example, the preferred embodiment illustrated in  FIGS. 1–7  employs a locking and unlocking mechanism  48  that responds to tension (exerted by the control lever  12  upon the first element  50 ) in different ways depending upon the relative positions of the locking and unlocking mechanism  48 . Other embodiments of the present invention employ locking and unlocking mechanisms that are subject to compression rather than tension when the control lever  12  is actuated. Three such mechanisms are illustrated in  FIGS. 8–10 . The three locking and unlocking mechanisms illustrated in  FIGS. 8–10  represent alternatives to the locking and unlocking mechanism  48  illustrated in FIGS.  1  and  2 – 6 . Each of the locking and unlocking mechanisms illustrated in  FIGS. 8–10  is an over-center device. As mentioned above, the locking and unlocking mechanism need not necessarily be an over-center device, although such devices are preferred. 
   With reference first to  FIG. 8 , the locking and unlocking mechanism  148  illustrated therein is another over-center device. The locking and unlocking mechanism  148  preferably has a first link  150  and a second link  152  articulated together by a common pivot  164 . Each of the links  150 ,  152  is preferably pivotable about another respective pivot  118 ,  154  located a distance from the common pivot  164 . The first link  150  is preferably pivotably connected to the control lever  112  while the second link  152  is pivotably connected to a wall  114  of the latch assembly  110 . 
   Like the other embodiments of the present invention described herein, the first and second links  150 ,  152  of the embodiment shown in  FIG. 8  can instead take any shape or form desired. Likewise, the relative sizes and dimensions of the links  150 ,  152  can be in any proportion desired and suitable for a particular application. 
   In the preferred embodiment illustrated in  FIG. 8 , the first link  150  and the control lever  112  each have a respective aperture  158 ,  160  through which extends a pivot pin  154 . The first link  150  and the control lever  112  can be connected in any of the manners described above with reference to the first preferred embodiment of the present invention. 
   One having ordinary skill in the art will appreciate that the first link  150  can be pivotably connected to the control lever  112  in a number of different manners permitting relative rotation between the first link  150  and the control lever  112 , each one of which falls within the spirit and scope of the present invention. Similarly, one having ordinary skill in the art will appreciate that the second link  152  can be mounted for pivotal movement within the latch assembly  110  in a number of different manners each also falling within the spirit and scope of the present invention. 
   By virtue of the common pivot  164  and the pivotable connection of the links  150 ,  152  to the outside handle control lever  112  and the latch assembly wall  114 , the links  150 ,  152  can assume a number of different rotational positions relative to one another. The locking and unlocking mechanism  148  therefore at least has a locked position and an unlocked position. In the unlocked position (shown in solid lines in  FIG. 8 ), the links  150 ,  152  are positioned at a slight angle with respect to one another and to one side of a line  166  passing through the dedicated linkage pivots  118 ,  154 . In the locked position (shown in dotted lines in  FIG. 8 ), the links  150 ,  152  are positioned at an angle with respect to one another and to another side of the line  166  passing through the dedicated linkage pivots  118 ,  154 . 
   In their unlocked position to one side of the line  166 , the links  150 ,  152  are capable of resisting force exerted by the control lever  112 , and transmit such force from the first link  150  through the common pivot  164  and second link  152  and to the pivot  154  of the second link  152  (or to an element connected to the second link  152  if the linkage pivot  154  of the second link  152  is attached to such an element). When the links  150 ,  152  are in their locked position to the other side of the line  166 , the links  150 ,  152  are incapable of resisting such force from the control lever  112 . 
   When the control lever  112  is pivoted by an actuation force as described above, the control lever  112  pivots about or near the pivot  118  which is preferably held substantially in place by the links  150 ,  152  in their unlocked position shown in solid lines in  FIG. 8 . Force transmitted by actuation of the control lever  112  (a lifting direction at the right-hand end of the control lever  112  in  FIG. 8 ) is transmitted from the pivot  118  in an upward direction to the links  150 ,  152 . In their unlocked positions, the links  150 ,  152  are preferably prevented from pivoting farther away from the line  166  running through the dedicated linkage pivots  118 ,  154  by one or more stops  168  on the latch assembly wall  114 . The stops  168  limit the amount of movement of the locking and unlocking mechanism  148  in one direction away from the line  166 . The stops  168  are preferably posts, blocks, walls, or other protrusions extending from the latch assembly wall  114 , but can instead be elements connected to the latch assembly wall  114  or other stationary structure of the latch assembly  110  adjacent to the locking and unlocking mechanism  148 . 
   One having ordinary skill in the art will appreciate that the links  150 ,  152  can be prevented from over-rotating in their unlocked positions (i.e., in a direction farther away from the line  166 ) in any number of different manners. By way of example only, the stops  168  can be located in a number of other positions adjacent to either link  150 ,  152  to still prevent linkage over-rotation away from the line  166  in the unlocked position. As another example, any of the three pivots  164 ,  118 ,  154  can have a limited rotational range which prevents further rotation of the connected links  150 ,  152  once an unlocked position has been reached such as that shown in solid lines in  FIG. 8 . Pivots having a limited rotational range and for limiting the rotational range of connected elements are conventional in structure and operation and are not therefore described further herein. As another example, the common pivot  164  can be received within a groove, slot, or other aperture in an adjacent wall  114  of the latch assembly housing (not shown) which defines a limit to which the common pivot  164  (and therefore the links  150 ,  152 ) can move away from the line  166  in the unlocked position. As yet another example, either or both links  150 ,  152  can have one or more posts, fingers, walls, or other elements extending therefrom into recesses, slots, grooves, holes, or other apertures in a wall  114  of the latch assembly housing. The aperture(s) can thereby limit the range of linkage motion past the line  166  in much the same way as the common pivot  164  and aperture embodiment just described. Alternatively, an element can extend from a wall  114  of the latch assembly housing to an aperture in either link  150 ,  152  to perform the same function. Still other manners of limiting linkage motion past the line  166  in the unlocked position are possible and fall within the spirit and scope of the present invention. 
   As described above, when the links  150 ,  152  are in the unlocked position to one side of the line  166  running through the dedicated linkage pivots  118 ,  154 , the links  150 ,  152  can resist motion of the control lever  112  by resisting movement of the pivot  118 . Therefore, actuation of one end  170  of the control lever  112  (when the links  150 ,  152  are in their unlocked position) causes the control lever  112  to pivot about or near the pivot  118 , which acts as a fulcrum so that the opposite end  172  of the control lever  112  acts upon the pawl post  144  and releases the pawl  128 . 
   When the links  150 ,  152  are moved to the locked position on the opposite side of the line  166  through the dedicated linkage pivots  118 ,  154 , the control lever  112  is moved away from the pawl  128 . Although not required, the control lever  112  preferably remains pivotable about the same point with respect to the control lever  112  (i.e., the control lever pivot  118  in the embodiment shown in  FIG. 8 ). In the locked position of the links  150 ,  152 , actuation of the control lever  112  preferably causes the control lever  112  to pivot about the control lever pivot  118 . Therefore, actuation of one end  170  of the control lever  112  (when the links  150 ,  152  are in their locked position) causes the control lever  112  to pivot about or near the control lever pivot  118  without exerting any force or sufficient force upon the pawl post  144  to move and release the pawl  128 . The locked position of the links  150 ,  152  is shown in dotted lines in  FIG. 8 . 
   In some highly preferred embodiments, the first and second links  150 ,  152  do not move or do not move significantly when the control lever  112  is actuated in either the locked state or the unlocked state of the locking and unlocking mechanism  148 . However, in other embodiments, both links  150 ,  152  are free to move in their locked or unlocked state when the control lever  112  is actuated. Therefore, in such alternative embodiments, rotation of the control lever  112  about the control lever pivot  118  in the locked state is not exclusive (the control lever  112  also pivots about a second point located a distance from the control lever pivot  118 ). 
   Although the present invention can operate without any bias placed upon the outside handle locking and unlocking mechanism  148 , this mechanism  148  is more preferably biased into either of its locked and unlocked positions and is most preferably biased into both positions as will be described below. Specifically, when the links  150 ,  152  have been rotated so that the common pivot  164  is on one side of the line  166  running through the dedicated linkage pivots  118 ,  154 , actuation of the control lever  112  will preferably only force the links  150 ,  152  in a direction away from the line  166 . Therefore, the locking and unlocking mechanism  148  is operable to lock and unlock the control lever  112  without being biased by any additional elements or structure. However, some preferred embodiments of the present invention have one or more biasing elements directly or indirectly coupled to the links  150 ,  152  to bias them into either or both locked and unlocked positions. 
   The biasing elements can be torsion springs  174  connected to the dedicated linkage pivots  118 ,  154  and/or to the common pivot  164  in any conventional manner to exert a rotational force upon the links  150 ,  152  toward the stable positions on either side of the center position of the locking and unlocking mechanism  148 . Alternatively, the links  150 ,  152  can be biased toward either or both stable positions by one or more springs connected to a wall  114  of the latch assembly housing (not shown) and to either or both links  150 ,  152 , by one or more magnet sets connected to the links  150 ,  152  and to the latch assembly wall  114  (e.g., opposed magnets on the links  150 ,  152  and on the latch assembly wall  114  at the line  166  running through the dedicated linkage pivots  118 ,  154 , attracting magnets on the links  150 ,  152  and on either side of the line  166 , etc.), and the like. In any case, where the locking and unlocking mechanism  148  employs a biasing element or mechanism biasing the links  150 ,  152  into locked and/or unlocked positions, the biasing element or mechanism biases the links  150 ,  152  in a direction toward the stable positions of the locking and unlocking mechanism  148 . In the illustrated preferred embodiment for example, the links  150 ,  152  can be biased toward the unlocked position shown in solid lines in  FIG. 8  when the common pivot  164  has crossed the line  166  in a direction toward the unlocked position (although the biasing force can be applied before or after crossing the line  166  as described in greater detail above with regard to the first preferred embodiment). Similarly, the links  150 ,  152  can be biased toward the locked position shown in dotted lines in  FIG. 8  after, before, or as the common pivot  164  has crossed the line  166  in a direction toward the locked position. 
   In some alternative embodiments of the present invention, the links  150 ,  152  are not biased into both locked and unlocked positions, but are instead biased into one of these positions. In such cases, the links  150 ,  152  are preferably rotated toward the biased direction until acted upon by the biasing element(s), after which time the links  150 ,  152  preferably continue their rotation to a desired position under biasing force. When the links  150 ,  152  have been rotated sufficiently in an opposite direction, the links  150 ,  152  can remain in their position until actuated and are preferably not biased back toward and across the line  166 . 
   The unlocked and locked positions of the locking and unlocking mechanism  148  described above and illustrated in the figures is to the left and right of the line  166  passing through the dedicated linkage pivots  150 ,  152 . However, the operational principles of the locking and unlocking mechanism  148  according to the present invention are not limited to or defined by the particular orientation of the locking and unlocking mechanism  148 . This mechanism can be oriented in any manner desired based at least in part upon the particular latch application at hand and the positions and orientations of control levers in the latch assembly. Also, the angle between the links  150 ,  152  in their locked and unlocked positions can be different than those shown in  FIG. 8 . The angle between the links  150 ,  152  facing the line  166  in each position is at least less than 180 degrees when the control lever  112  is not actuated. 
   In operation, one or both links  150 ,  152  of the locking and unlocking mechanism  148  are preferably actuated to pivot about the common pivot  164  and to move the common pivot  164  across the line  166  running through the dedicated linkage pivots  118 ,  154 . For example, when the common pivot  164  in the illustrated preferred embodiment of  FIG. 8  is moved to the right across the center line  166 , the locking and unlocking mechanism  148  is placed in its locked state. Specifically, when the control lever  112  is actuated as described above (rotated counter-clockwise as shown by the arrow in  FIG. 8 ), the control lever  112  pivots about the control lever pivot  118  without imparting force or sufficient force to the pawl post  144  to release the pawl  128 . Because the links  150 ,  152  are preferably biased into the locked position, forces from vibration, shock, repeated control lever actuation, and other sources will not cause the locking and unlocking mechanism  148  to slip from its locked position. 
   When the common pivot  164  in the illustrated preferred embodiment of  FIG. 8  is moved to the left across the center line  166 , the locking and unlocking mechanism  148  is placed in its unlocked state. Specifically, when the control lever  112  is actuated as described above (rotated counter-clockwise as shown by the arrow in  FIG. 8 ), the links  150 ,  152  preferably abut the stops  168  and are prevented from pivoting further about the common pivot  164 . The links  150 ,  152  therefore hold the control lever pivot  118  in place or at least from substantial movement. The control lever  112  pivots about or near this pivot  118  and forces the pawl post  144  to move sufficiently to release the pawl  128 . Because the links  150 ,  152  are preferably biased into the unlocked position, forces from vibration, shock, repeated control lever actuation, and other sources will not cause the locking and unlocking mechanism  148  to slip from its unlocked position. 
   It will be appreciated by one having ordinary skill in the art that the latch inputs for moving the links  150 ,  152  between their locked and unlocked states can take any number of different forms. For example, either link  150 ,  152  can be directly or indirectly connected to an output shaft of a motor, a plunger rod, a cable, a link, or any other element or mechanism connected to a locking and unlocking input (such as a cylinder lock, a sill button, a locking lever, electronic lock controls, and the like). 
   The locking and unlocking mechanism  148  illustrated in  FIG. 8  is another example of a mechanism that can be used to move the control lever  112  with respect to the pawl  128 . As mentioned above, in some preferred embodiments the control lever  112  is pivotable about the same point with respect to the control lever  112  (e.g., control lever pivot  18  in the first preferred embodiment and control lever pivot  118  in the second preferred embodiment) in both locked and unlocked states. It should be noted that in each embodiment of the present invention employing such a control lever, the control lever can pivot about the same point with respect to the control lever in any state of the locking and unlocking mechanism. Specifically, the control lever in some embodiments is always pivotable about the same location with respect to the control lever regardless of the position and orientation of the locking and unlocking mechanism. In other embodiments, the control lever is pivotable about the same location with respect to the control lever only in fully locked and unlocked states of the locking and unlocking mechanism. When in transition between these states, the control lever can be pivotable about one or more other pivot locations with respect to the control lever. 
   In those embodiments of the present invention in which the control lever is pivotable about the same point with respect to the control lever in both locked and unlocked states, the control lever need not rotate exclusively about the subject point. In some embodiments, the control lever can also pivot simultaneously about another point in either state. 
   Still other elements and mechanisms exist for moving the control lever  12 ,  112  with respect to the pawl  28 ,  128  while (in some preferred embodiments) keeping the pivot point of the control lever  12 ,  112  in the same location with respect to the control lever  12 ,  112 . Although not required in some embodiments of the present invention, over-center devices are preferred. Two additional examples of such mechanisms are illustrated in  FIGS. 9 and 10 . Like the locking and unlocking mechanisms of the first and second preferred embodiments described above, these alternative mechanisms preferably have a stable locked position and a stable unlocked position from which the mechanism will not shift even under significant vibration, repeated input actuation, and harsh operating conditions. Also like the earlier-described locking and unlocking mechanisms, each of these alternative mechanisms are preferably biased into these stable positions by one or more biasing elements (such as springs, magnets, and the like). 
   With reference first to the locking and unlocking mechanism of  FIG. 9 , a first element  250  is positioned relative to a second element  252  for engagement therewith. The second element  252  of the locking and unlocking mechanism  248  has a ramped surface  276  and is movable with respect to the first element  250  of the locking and unlocking mechanism  248 . The second element  252  can take any shape having a ramped surface  276 , such as a wedge shape as shown in  FIG. 9 . The first element  250  is preferably biased in a direction toward the second element  252  by one or more springs (not shown) connected to or otherwise positioned to exert force against the first element  250  or the control lever  212 . Alternatively, the first element  250  can be biased toward the second element by one or more electro-magnet sets (on the first and second elements  250 ,  252 , on the first element  250  and in a position adjacent to the second element  252 , and the like. 
   When the first and second elements  250 ,  252  are relatively positioned so that the first element  250  is biased against the ramped surface  276  of the second element  252 , the second element  252  preferably moves to the right as shown in  FIG. 9  under biasing force from the first element  250  against the ramped surface  276 . The first and second elements  250 ,  252  therefore have a stable position in which the first element  250  is at the “bottom” of the ramped surface  276 . The second element  252  also preferably has a recess  278  at the “top” of the ramped surface  276  for receiving the first element  250  when the second element  252  has been actuated until the recess  278  is aligned with the first element  250 . When thus aligned, the first element  250  preferably engages with the second element  252  and thereby secures the second element  252  in place with respect to the first element  250 . This defines a second stable position of the elements  250 ,  252 . Although a recess  278  in the second element  252  is preferred, a number of other surface features also provide a stable position of the second element  252  relative to the first element  250  at the “top” of the ramped surface  276 , including without limitation a slot, dimple, aperture, step, plateau, groove, and the like in the second element  252 . 
   As with the locking and unlocking mechanisms  48 ,  148  of the two illustrated preferred embodiments described above, the two stable positions of the elements  250 ,  252  are separated by at least one intermediate unstable position. The first element  250  can be connected to the control lever  212  to move the control lever  212  with respect to the pawl post  244  and to thereby place the control lever  212  in locked and unlocked states (wherein actuation such as rotation of the control lever  212  as shown by the arrows in  FIG. 9  is incapable and capable of sufficiently moving the pawl post  244  to release the ratchet, respectively). 
   The third preferred embodiment of the present invention illustrated in  FIG. 9  also provides an example of how the control lever  212  can be moved by the locking and unlocking mechanism  248  in different manners with respect to the pawl  228 . In the third preferred embodiment, the control lever  212  is translatable with respect to the pawl  228  between a position adjacent to the pawl post  244  and a position removed from the pawl post  244 . In the first two embodiments described above and illustrated in  FIGS. 1–8 , the control lever  12 ,  112  is rotatable between such positions or is movable between such positions by a combination of rotation and translation. It should be noted that the control lever of the present invention can move with respect to the pawl in any manner desired. Any type of movement capable of positioning the control lever in an unlocked position (in which the control lever can be actuated to move the pawl and release the ratchet) and in a locked position (in which the control lever is incapable of moving or sufficiently moving the pawl to release the ratchet) can be employed. 
   The alternative embodiment of the present invention illustrated in  FIG. 10  functions in a similar manner to the  FIG. 9  embodiment described above. Rather than employ an element having a ramped surface such as that of the second element  252 , the locking and unlocking mechanism  348  preferably includes a second element  352  mounted to rotate about an axis  354  adjacent to the first element  350 . The second element  352  is preferably eccentric with respect to the axis  354 , is lobed, or is otherwise shaped so that all or a portion of the second element  352  moves toward and away from the first element  350  when the second element  352  is rotated about the axis  354 . The rotating second element  352  can have a first stable position in which the second element  352  is rotated away from the first element  350  and can be biased into another stable position (e.g., rotated toward the first element  350 ) by one or more biasing elements. For example, the second element  352  can be mounted upon a pivot  380  having a conventional spring thereon biasing the second element  352  toward the first element  350 . 
   Therefore, the second element  352  is normally biased into a stable position rotated toward the first element  350 , but has another stable position rotated away from the first element  350  and preferably retained therein under biasing force from the second element  352 . As another example, the second element  352  can have a recess or other surface feature (similar to that described above with reference to the second element  252  in the  FIG. 9  embodiment) preferably aligned with the first element  350  when the second element  352  is rotated toward the first element  350 . The first element  350  engages with the recess of the second element  352  to define a second stable position of the locking and unlocking mechanism  348 . 
   As with the locking and unlocking mechanisms  48 ,  148 ,  248  of the illustrated preferred embodiments described above, the two stable positions of the elements  350 ,  352  are separated by at least one intermediate unstable position. The first element  350  can be connected to the control lever  312  to move the control lever  312  with respect to the pawl post  344  and to thereby place the control lever  312  in locked and unlocked states (wherein actuation such as rotation of the control lever  212  as shown by the arrows in  FIG. 9  is incapable and capable of sufficiently moving the pawl post  244  to release the ratchet, respectively). 
   It should be noted that the particular type of locking and unlocking mechanism employed (whether an over-center device or not) is independent of the type(s) of force exerted by and upon the locking and unlocking mechanism and its elements when the control lever  12 ,  112 ,  212 ,  312  is actuated. For example, the locking and unlocking mechanism  348  of the fourth preferred embodiment illustrated in  FIG. 10  could potentially be placed in a state where actuation of the control lever  312  places the elements  350 ,  352  in almost complete compression. In contrast, the locking and unlocking mechanism  148  of the second preferred embodiment illustrated in  FIG. 8  can experience a combination of forces when in the unlocked state. These forces can include rotational and compressive forces with little to no tensile forces. In yet another example as shown in  FIGS. 1–7 , the first element  50  of the locking and unlocking mechanism  48  can experience forces that are mostly or all tensile. Other types of locking and unlocking mechanisms fall within the spirit and scope of the present invention, and can experience any combination of tensile, compressive, and moment forces in reaction to control lever actuation in either or both locked and unlocked states of such mechanisms. 
   Each of the illustrated preferred embodiments described above has a control lever  12 ,  112 ,  212 ,  312  which is pivotable about the same location with respect to the control lever  12 ,  112 ,  212 ,  312  in both locked and unlocked states of the control lever  12 ,  112 ,  212 ,  312 . Although this feature is preferred in the various illustrated embodiments, it is not a required feature for other embodiments of the present invention. For example, some embodiments of the present invention employ the over-center locking and unlocking mechanisms, yet have a control lever that pivots about different locations with respect to the control lever when in a locked state and in an unlocked state. In other words, the over-center locking and unlocking mechanism of the present invention can be employed with control levers that are movable in any manner. 
   By way of example only, an alternative embodiment of the locking and unlocking mechanism  48  of  FIGS. 1–7  is illustrated in  FIGS. 11–14  (elements and features of the embodiment shown in  FIGS. 11–14  corresponding to those of the embodiment shown in  FIGS. 1–7  have corresponding reference numerals in the 400 series). In this embodiment, the locking and unlocking mechanism  448  is an over-center device, but is not biased by a spring or other biasing device into fully-rotated locked and unlocked positions as described above. Instead, actuation of the control lever  412  draws the first element  450  and the pivot post  464  to the side of the center line  466  on which the pivot post  464  is already located. Further actuation of the control lever  412  preferably draws the pivot post  464  and the second element  452  around the axis  454 . Therefore, the control lever  412  can be placed in its locked and unlocked states by directly or indirectly rotating the pivot post  464  to one side or the other of center line  466  (without necessarily rotating or biasing the pivot post  464  to any particular position past the center line  466 ). If not already rotated to a stopped position as described above, subsequent actuation of the control lever  412  will rotate the second element  452  further in the same direction. 
   With reference to  FIG. 11 , when the second element  452  is rotated to the right side of the center line  466 , the control lever  412  is in its unlocked position as described above. However, subsequent actuation of the control lever  412  as shown in  FIG. 12  causes the first element  450  to rotate the second element  452  clockwise. Preferably, rotation of the second element  452  is limited in this direction as described in greater detail with reference to the first preferred embodiment illustrated in  FIGS. 1–7 . Therefore, the control lever  412  preferably pivots about the pawl post  444  rather than about the control lever pivot  418  until the second element  452  is stopped. Further actuation of the control lever  412  rotates the control lever  412  about the control lever pivot  418  while the control lever  412  moves the pawl post  44  to release the pawl  428  (see  FIG. 12 ). With reference to  FIG. 13 , when the second element  452  is rotated to the left side of the center line  466 , the control lever  412  is in its locked position as described above. However, subsequent actuation of the control lever  412  as shown in  FIG. 14  causes the first element  450  to rotate the second element  452  counter-clockwise. Preferably, rotation of the second element  452  is not limited in this direction (such as by one or more stops). Therefore, the control lever  412  preferably pivots about the pawl post  444  rather than about the control lever pivot  418  as shown in  FIG. 14 . This motion imparts no motive force to the pawl  428 , or at least insufficient motion to trigger pawl release. 
   By operating in the manner just described, the control lever  412  pivots about different points in the locked and unlocked states of the control lever  412  (i.e., about the control lever pivot  418  in the locked state and about the pawl post  444  and control lever pivot  418  in the unlocked state). The embodiment of the present invention illustrated in  FIGS. 11–14  is an example of the manner in which the over-center locking and unlocking mechanism of the present invention can be employed to control the motion of control levers in different latch assembly arrangements. 
   As another example, an alternative embodiment of the locking and unlocking mechanism  48  of  FIG. 8  is illustrated in  FIG. 15  (elements and features of the  FIG. 8  embodiment corresponding to those of the embodiment shown in  FIG. 15  have corresponding reference numerals in the  500  series). In the  FIG. 15  embodiment, the locking and unlocking mechanism  548  is an over-center device, but is not biased by a spring or other biasing device into fully-rotated locked and unlocked position as described above. Instead, actuation of the control lever  512  draws the common pivot  564  to the side of the center line  566  on which the common pivot  564  is already located. Further actuation of the control lever  512  preferably draws the common pivot  564  and the links  550 ,  552  into the same direction away from the center line  566 . Therefore, the control lever  512  can be placed in its locked and unlocked states by directly or indirectly moving the common pivot  564  to one side or the other of center line  566  (without necessarily moving or biasing the pivot post  464  and links  550 ,  552  to any particular positions past the center line  566 ). If not already rotated to a stopped position as described above, subsequent actuation of the control lever  512  will rotate the first and second links  550 ,  552  further in the same direction. 
   With continued reference to  FIG. 15 , when the common pivot  564  is moved to the right side of the center line  566 , the control lever  512  is in its locked position as described above. Subsequent actuation of the control lever  512  causes the first and second links  550 ,  552  to continue pivoting away from the center line  566 . Preferably, rotation of the first and second links  550 ,  552  is not limited in this direction (such as by one or more stops). Therefore, the control lever  512  preferably pivots about a location closer to or adjacent to the pawl post  544  rather than about the control lever pivot  518 . This motion imparts no motive force to the pawl  528 , or at least insufficient motion to trigger pawl release. When the common pivot  564  is moved to the left side of the center line  566 , the control lever  512  is in its unlocked position as described above. Subsequent actuation of the control lever  512  causes the first and second links  550 ,  552  to continue pivoting away from the center line  566 . Preferably, rotation of the first and second links  550 ,  552  is limited in this direction as described in greater detail with reference to the second preferred embodiment illustrated in  FIG. 8 . Therefore, the control lever  512  preferably pivots closer to or near the pawl post  544  rather than about the control lever pivot  518  until the first and second links  550 ,  552  are stopped. Further actuation of the control lever  512  rotates the control lever  512  about the control lever pivot  518  while the control lever  512  moves the pawl post  544  to release the pawl  528 . 
   By operating in the manner just described, the control lever  512  pivots about different points in the locked and unlocked states of the control lever  512 . The  FIG. 15  embodiment is another example of the manner in which the over-center locking and unlocking mechanism of the present invention can be employed to control the motion of control levers in different latch assembly arrangements. It should be noted that the control levers  412 ,  512  of the embodiments illustrated in  FIGS. 11–15  need not necessarily pivot about one point in any given range of motion of the control levers  412 ,  512 . One having ordinary skill in the art will appreciate that the control levers  412 ,  512  in these and other embodiments can simultaneously pivot about two different points and/or can pivot about a point that moves with respect to the control lever  412 ,  512  or with respect to the pawl  428 ,  528  as the control lever  412 ,  512  is actuated. The over-center device of the present invention can be employed to control the motion of control levers moving in any of these manners. 
   In some applications of the present invention, it may be desirable or necessary to locate the control lever of the latch assembly a distance from the pawl. In such applications, the control lever can be connected to the pawl by one or more links, rods, or other elements capable of transmitting force from the control lever to the pawl. Such embodiments preferably operate in a manner similar to the latch assemblies illustrated in  FIGS. 1–15 . An example of such an embodiment is illustrated in  FIGS. 16–19 . The latch assembly  610  in  FIGS. 16–19  is similar in a number of manners to that of  FIGS. 1–7 . Elements and features of the embodiment shown in  FIGS. 16–19  corresponding to those of the embodiment shown in  FIGS. 1–7  have corresponding reference numerals in the 600 series. 
   In this embodiment, the control lever  612  is not directly connected to the pawl  628 , but is instead connected thereto by a link  682 . Although illustrated as an elongated member connected at opposite ends to the control lever  612  and pawl  628 , respectively, the link  682  can have any shape desired. Preferably, the link  682  is rotatably connected to the control lever  612  and to the pawl  628 , with at least one of these connections being a lost-motion connection. The link  682  can be rotatably connected to the control lever  612  by a pivot  684 , and can be rotatably connected to a pawl post  644  received within an elongated aperture  646  in the link  682 . The connection between the link  682  and the pawl  628  is preferably similar in nature to the connection between the control lever  12  and pawl  28  described above, and can take other forms as described in greater detail with reference to the first preferred embodiment illustrated in  FIGS. 1–7 . 
     FIGS. 16–19  illustrates another example of a locking an unlocking mechanism according to the present invention. The locking and unlocking mechanism (indicated generally at  648 ) is preferably similar to that of the first preferred embodiment illustrated in  FIGS. 1–7 , and has first and second elements  650 ,  652 , a pivot post  664  connecting the first and second element  650 ,  652 , a control lever pivot  618 , and a center position  666  as described above with reference to the first preferred embodiment. Preferably, neither of the connections between the first and second elements  650 ,  652  and between the first element  650  and the control lever  612  are lost-motion connections, although either or both connections can be lost-motion connections if desired. 
   The locking and unlocking mechanism  648  is another example of an over-center device used to position the control lever  612  with respect to the pawl  628 . In contrast to some of the over-center devices  48 ,  448  described above, the locking and unlocking mechanism is placed generally in compression when the control lever  612  is actuated. However, other locking and unlocking mechanisms (whether over-center or otherwise) as described herein can be employed. 
   With the exceptions described below, the locking and unlocking mechanism  648  preferably operates in a manner similar to the locking and unlocking mechanism illustrated in  FIGS. 1–7 . With reference to  FIG. 16 , the second element  652  can be rotated in one direction (counter-clockwise as viewed in  FIGS. 16–19 ) to move the pivot post  664  to one side of the center position  666  of the second element  652 . The second element  652  preferably rotates until stopped by one or more stops (not shown). As shown in  FIG. 17 , the control lever  612  in this position is incapable of moving the pawl  628  due to the lost-motion connection with the pawl  628  as described above. Specifically, subsequent actuation of the control lever  612  causes the control lever  612  to pivot about the control lever pivot  612 , whereby force is transferred through the first element  650  to the stopped second element  652  while the link  682  moves with respect to the pawl  628 . Therefore, the control lever  612  is locked in this state. 
   With reference next to  FIG. 18 , the second element  652  can instead be rotated in an opposite direction (clockwise as viewed in  FIGS. 16–19 ) to move the pivot post  664  to an opposite side of the center position  666  of the second element  652 . The second element  652  preferably rotates until stopped by one or more stops (also not shown). As shown in  FIG. 19 , the control lever  612  in this position can move the pawl  644  due to the position of the pawl post  644  in the link aperture  646 . Specifically, subsequent actuation of the control lever  612  causes the control lever  612  to pivot about the control lever pivot  618 , whereby force is transferred through the first element  650  to the stopped second element while the link  682  pushes the pawl post  644  to move the pawl  628 . Therefore, the control lever  612  is unlocked in this state. 
   Although the locking and unlocking mechanisms  48 ,  148 ,  248 ,  348 ,  448 ,  548 ,  648  described above and illustrated in the figures are each an over-center device, any other element, device, or mechanism capable of moving the control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612  to different positions with respect to the pawl  28 ,  128 ,  228 ,  328 ,  428 ,  528 ,  628  can instead be employed. By way of example only, the control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612  can be connected in any conventional manner to a solenoid, hydraulic or pneumatic cylinder, motor, or any other driving device capable of moving the control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612 . In other embodiments, the control lever can be driven by an electro-magnet set on the control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612  and on a latch assembly housing wall  14 ,  114 ,  214 ,  314 ,  414 ,  514 ,  614  or other structure adjacent to the control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612 , can be cammed against or otherwise moved directly or indirectly by one or more rotating elements driven by an electric motor, and the like. Any element, device, or mechanism that can be employed to move the control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612  to different positions in the latch assembly  10 ,  110 ,  210 ,  310 ,  410 ,  510 ,  610  is considered to fall within the spirit and scope of the present invention. 
   In this regard, it should be noted that an element, device, or mechanism can be used to move the control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612  to one position and a second element, device, or mechanism can be used to move the control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612  to another position. For example, an actuator can push a peripheral edge of the control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612  to move the control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612  to an unlocked position with respect to the pawl  28 ,  128 ,  228 ,  328 ,  428 ,  528 ,  628 , while one or more springs or other biasing elements connected to the control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612  can push or pull the control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612  back to a locked position when the actuator is released. 
   In some embodiments of the present invention described above, the elements defining the locking and unlocking mechanism do not move or are relatively stationary in both their locked and unlocked states. For example, the locking and unlocking mechanisms  48 ,  148  in the first and second preferred embodiments illustrated in  FIGS. 1–7  and  8 , respectively, are biased into their locked and unlocked positions as described above. When the control levers  12 ,  112  in such embodiments are actuated while the locking and unlocking mechanisms  48 ,  148  are in their locked states, the locking and unlocking mechanisms  48 ,  148  remain stationary or substantially stationary. Alternatively however, either or both components  50 ,  52 ,  150 ,  152  of these mechanisms can move to some degree in either or both states, such as through an amount of rotation, shifting, or other movement responsive to control handle actuation. 
   In other embodiments of the present invention described above, the elements defining the locking and unlocking mechanism do not move or are relatively stationary when the control lever is actuated in one state (e.g., locked or unlocked) but can and do move when the control lever is actuated in another state (e.g., unlocked or locked, respectively). The illustrated preferred embodiments of  FIGS. 9 and 10  provide examples of such locking and unlocking mechanisms. 
   In still other embodiments, the locking and unlocking mechanism is movable in both states: a locked state in which the elements defining the locking and unlocking mechanism are movable but incapable of transmitting sufficient motive force to the pawl to unlatch the latch, and an unlocked state in which these elements are movable and capable of transmitting sufficient motive force to the pawl to unlatch the latch. 
   Latch assemblies employing over-center locking and unlocking mechanisms (used to lock and unlock a control lever) have a number of significant advantages over latch assemblies with conventional locking and unlocking mechanisms. Unlike conventional mechanisms, a number of embodiments of the over-center locking and unlocking mechanism can hold themselves in locked or unlocked positions against forces applied by the control lever without power supplied to the locking and unlocking mechanisms. Also, over-center locking and unlocking mechanisms can help to retain the control lever in its locked or unlocked state against forces that can be generated upon release of the user-manipulatable device (e.g., door handle or lever) connected to the control lever. In addition, the present invention can employ one or more pivot joints for moving the locking and unlocking mechanism between its locked and unlocked states. 
   In order for a number of conventional latch assemblies to properly respond to an unlatching input to the latch assembly, at least one linkage, mechanism, or element must engage with at least one other linkage, mechanism, or element. In contrast, the use of an over-center locking and unlocking mechanism as described above can eliminate the need for such engagement and disengagement operations and can thereby result in smoother latch operation. Also, an over-center locking and unlocking mechanism can be well-suited for exerting force against a partially or fully-actuated control lever so that movement of the mechanism to an unlocked position generates pawl release (as will be described in greater detail below). 
   Unlike many conventional locking and unlocking mechanisms, the locking and unlocking mechanism in some embodiments of the present invention can be connected to the control lever (see, for example, the embodiments of the present invention shown in  FIGS. 1–19 ). Such connection to the control lever can stabilize control lever movement and can provide additional control over the control lever. In addition, because the elements of the locking and unlocking mechanism  48 ,  148 ,  248 ,  348 ,  448 ,  548 ,  648  can be of any length and shape, the latch input(s) (solenoids or other actuators, mechanical connections to cables, rods, or other elements, and the like) to the locking and unlocking mechanism can be located a distance from the subject control lever, thereby permitting the locking and unlocking mechanism to be readily adapted to a number of different latch assemblies. Also, the relative lengths of the elements in the locking and unlocking mechanism can be adjusted to provide for different mechanical advantages of the locking and unlocking mechanism  48 ,  148 ,  248 ,  348 ,  448 ,  548 ,  648  without requiring a change in the location of the input(s) connected to the locking and unlocking mechanism  48 ,  148 ,  248 ,  348 ,  448 ,  548 ,  648 . 
   In each embodiment of the present invention described above, the locking and unlocking mechanism  48 ,  148 ,  248 ,  348 ,  448 ,  548 ,  648  is connected to a control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612 . However, it should be noted that the locking and unlocking mechanism of the present invention need not necessarily be connected to the control lever in order to perform the functions described above. 
   For example, the first element or link  50 ,  150 ,  250 ,  350 ,  450 ,  550 ,  650  can be positioned to move and hold the control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612  in a desired position in a number of different manners, such as by one or more external surfaces of the first element or link  50 ,  150 ,  250 ,  350 ,  450 ,  550 ,  650  blocking movement of the outside handle control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612  in one or more directions. By way of example only, and with reference to the embodiment of the present invention illustrated in  FIG. 8 , the first link  150  need not necessarily be connected to the control lever  112  by the pivot  118 . An end of the first link  150  can instead press against an edge, side, or other surface of the control lever  112  to move the control lever  112  with respect to the pawl  128 . For improved engagement of the first link  150  with the control lever  112  in such a case, the control lever  112  can be shaped (with a recess, elbow, groove, and the like) to urge the end of the first link  150  into a desired contact area of the control lever  112 . Therefore, in some preferred embodiments of the present invention, the locking and unlocking mechanism need not necessarily be connected to a control lever to place the control lever in its locked and unlocked states. A linkage of the locking and unlocking mechanism should at least be movable into and out of a position whereby a surface of the linkage blocks, retains, or otherwise limits motion of the control lever. It should be noted that motion of the control lever in this state can be limited to rotation about or near the point at which the linkage blocks, retains, or otherwise limits motion of the control lever (as is the case in the preferred embodiments illustrated in  FIGS. 1–19 ), or can be limited to sliding, translation, or other types of movement in other embodiments of the present invention. 
   In the preferred embodiments of the present invention illustrated in  FIGS. 1–19 , the control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612  moves in one manner when blocked, retained, or otherwise limited by a locking and unlocking mechanism  48 ,  148 ,  248 ,  348 ,  448 ,  548 ,  648  and in another manner when not so blocked, retained, or otherwise limited by the locking and unlocking mechanism  48 ,  148 ,  248 ,  348 ,  448 ,  548 ,  648 . These manners of motion do not necessarily have to correspond to the unlocked and locked states of the control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612  as is the case in the illustrated preferred embodiments. One having ordinary skill in the art will appreciate that the locked and unlocked states can be reversed in other embodiments of the present invention, given readily identifiable changes in control lever and unlocking and locking element positions, connections, and relative orientations. Examples of such changes include relocation of the pawl post  44 ,  144 ,  244 ,  344 ,  444 ,  544 ,  644  to a different position with respect to the control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612  and/or changing the location of the locking and unlocking mechanism to block, retain, or otherwise limit another portion of the control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612 , and the like. One aspect of the present invention resides not in the manner in which a control lever triggers release of the pawl, but in how the control lever is placed in its locked and unlocked positions (incapable and capable of moving to trigger pawl release) based upon the position of the locking and unlocking mechanism relative to the control lever. 
   As described above, the control lever can be blocked, retained, or otherwise limited in motion by the locking and unlocking mechanism in either or both of its locked and unlocked states. Therefore, it should be noted that the control lever need not necessarily be free to move without limitation from the locking and unlocking mechanism in the unlocked state. In different embodiments of the present invention, movement of the control lever can be partially or fully defined by the locking and unlocking mechanism in either or both states. 
   A number of preferred embodiments of the present invention have a significant advantage based upon the ability of the control lever to be moved a distance from the pawl when the control lever is in its locked state. Specifically, it is desirable in some applications to remove the control lever a distance from the pawl in the unlocked state. This distance reduces the ability of the control lever to exert force against the pawl due to severe impact, shock, or vibration of the latch assembly because the mass of the control lever is removed from the pawl. For example, in some embodiments such as the those illustrated in  FIGS. 8–10  and  15 , the control lever  112 ,  212 ,  312 ,  512  is moved so that it is located a distance from the pawl when the control lever  112 ,  212 ,  312 ,  512  is in its unlocked state. 
   Another significant advantage offered by some preferred embodiments of the present invention is the ability to unlatch the latch assembly after the control lever has been partially or fully actuated. This feature will be now be described with reference to the first embodiment of the present invention, although any of the illustrated preferred embodiments of  FIGS. 1–19  can have this capability as will be described in greater detail below. 
   With reference to  FIG. 6  of the first preferred embodiment, the latch assembly  10  is shown in its locked and actuated state. For example, the handle or other user-manipulatable device connected to the control lever  12  has been actuated but has not generated release of the pawl  28  because the control lever  12  is not in position with respect to the pawl  28  to move the pawl post  44 . However, if the locking and unlocking mechanism  48  is moved to its unlocked position while the control lever  12  is partially or completely actuated, the control lever  12  can preferably be driven to an unlocked position to release the pawl  28  without re-actuating the control lever  12 . This is in contrast to many conventional latch assemblies in which the control lever  12  must be re-actuated to release the pawl  28  in such a case. 
   With continued reference to  FIG. 6 , the locking and unlocking mechanism  48  can be moved to its unlocked state by clockwise rotation of the second element  52  about its axis  54 . By this rotation, the pivot post  64  is moved across the center position  66 , pulling the first element  50  in the same direction. Because the control lever  12  is connected to the first element  50 , the control lever  12  is thereby moved with respect to the pawl  28 . This motion of the control lever  12  causes the aperture  46  in the control lever  12  to move with respect to the pawl post  44 , eventually pushing the pawl post  44  and moving the pawl  28 . If the control lever  12  has been actuated sufficiently, the pawl  28  is released from the ratchet  30 . Therefore, movement of the locking and unlocking mechanism  48  from the unlocked state shown in  FIGS. 3 and 4  to the locked state shown in  FIGS. 5 and 6  when the control lever  12  has been actuated sufficiently generates release of the latch without re-actuation of the control lever  12 . 
   Although each of the illustrated embodiments of the present invention has the latch releasing capability just described, it should be noted that some embodiments do not. The other inventive aspects of the present invention described herein do not require this type of latch releasing capability. 
   As just mentioned, each of the illustrated preferred embodiments of  FIGS. 1–19  is capable of pawl release upon movement of the locking and unlocking mechanism  48 ,  148 ,  248 ,  348 ,  448 ,  548 ,  648  to an unlocked position without re-actuation of the control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612 . For example, movement of the locking and unlocking mechanism  148  of the second embodiment illustrated in  FIG. 8  to the left across the center position  66  after the control lever  112  has been actuated preferably causes the control lever  112  to move the pawl post  144  to release the pawl  128 . Movement of second element  252  in the locking and unlocking mechanism  248  of the third preferred embodiment to the left after the control lever  212  has been actuated preferably causes the control lever  212  to move the pawl post  244  and release the pawl  228 . As another example, rotation of the second element  352  in the locking and unlocking mechanism  348  of the fourth preferred embodiment to its unlocked position (shown in solid lines in  FIG. 10 ) after the control lever  312  has been actuated preferably causes the control lever  312  to move the pawl post  344  and release the pawl  328 . 
   Depending upon the relative positions of the elements defining the locking and unlocking mechanism  48 ,  148 ,  248 ,  348 ,  448 ,  548 ,  648  and the control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612  and depending upon the manner in which the locking and unlocking mechanism  48 ,  148 ,  248 ,  348 ,  448 ,  548 ,  648  is connected or otherwise acts upon the control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612 , the control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612  may need to be fully actuated to release the pawl  28 ,  128 ,  228 ,  328 ,  428 ,  528 ,  628  when the locking and unlocking mechanism  48 ,  148 ,  248 ,  348 ,  448 ,  548 ,  648  is moved to its unlocked state as described above. In other embodiments of the present invention, only partial actuation of the control lever  12 ,  112 ,  212 ,  312 ,  412 ,  512 ,  612  is required to generate pawl release in such a case. 
   The embodiments described above and illustrated in the figures are presented by way of example only and are not intended as a limitation upon the concepts and principles of the present invention. As such, it will be appreciated by one having ordinary skill in the art that various changes in the elements and their configuration and arrangement are possible without departing from the spirit and scope of the present invention as set forth in the appended claims. For example, each of the preferred embodiments illustrated in  FIGS. 1–19  employs an over-center biasing mechanism to retain a control lever in its locked and unlocked positions with respect to a pawl. Also, in the embodiments illustrated in  FIGS. 1–10  and  16 – 19 , the locking and unlocking mechanism causes the control lever to pivot about the same point with respect to the control lever in the locked and unlocked states of the control lever. While both of these latch features are highly desirable, it should be noted that latch assemblies according to the present invention can have either one of these features (rather than both) as desired. Specifically, a latch assembly according to the present invention can have a control lever that pivots about different points when locked and unlocked using an over-center locking and unlocking mechanism. Alternatively, a latch assembly according to the present invention can have a control lever that pivots about the same point with respect to the control lever using an element, actuator, or device that is not an “over-center” element, actuator, or device. 
   Throughout the specification and claims herein, when one element is said to be “coupled” to another, this does not necessarily mean that one element is fastened, secured, or otherwise attached to another element. Instead, the term “coupled” means that one element is either connected directly or indirectly to another element or is in mechanical communication with another element. Examples include directly securing one element to another (e.g., via welding, bolting, gluing, frictionally engaging, mating, etc.), elements which can act upon one another (e.g., via camming, pushing, or other interaction) and one element imparting motion directly or through one or more other elements to another element.