Patent Publication Number: US-8973418-B2

Title: Mechanical combination lock

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of U.S. Provisional Patent Application 61/644,380, filed May 8, 2012, which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention generally relates to mechanical combination locks, and more particularly, but not exclusively, to mechanical permutation locks. 
     BACKGROUND 
     Conventional mechanical combination locks suffer from a variety of limitations and disadvantages. For example, many conventional mechanical keypad locks can distinguish either multiple presses of a single button, or the sequence in which the buttons were pressed, but not both. Accordingly, there remains a need for further contributions in this area of technology. 
     SUMMARY 
     One embodiment of the present invention is a unique mechanical combination lock. Further embodiments, forms, features, aspects, benefits, and advantages of the present application shall become apparent from the description and figures provided herewith. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is an illustration of a locking system according to a first embodiment of the invention. 
         FIG. 2  is an exploded view of the locking column illustrated in  FIG. 1 . 
         FIG. 3  is a perspective view of a gearing unit used in the column of  FIG. 2   
         FIG. 4  is a perspective view of a cam used in the column of  FIG. 2 . 
         FIG. 5  illustrates an example interference device. 
         FIG. 6  is a perspective view of a carriage. 
         FIG. 7  is a schematic illustration of a reset mechanism. 
         FIG. 8  is an illustration of a subassembly of the system of  FIG. 1 . 
         FIG. 9  illustrates various interface states of example units. 
         FIG. 10   a  is an illustration of an example code input system. 
         FIG. 10   b  illustrates positional changes caused by the code input system of  FIG. 10   a.    
         FIG. 11  is an illustration of a locking system with an example input system according to a second embodiment of the invention. 
         FIG. 12   a  illustrates the operation of the locking system  FIG. 11  during entry of a first code. 
         FIG. 12   b  illustrates the operation of the locking system  FIG. 11  during entry of a second code. 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates. 
       FIG. 1  illustrates an exemplary locking system  100 . System  100  can be employed in any fashion known in the art, such as, for example, as a door lock, bike lock, or padlock. System  100  includes a housing  192 , which houses a reset device  170 , columns  200 , a carriage  600 , and a fence (not labeled in  FIG. 1 ). Each column  200  comprises a plurality of gear units  300  and cams  400 . Each unit  300  is coaxially associated with a cam  400 , defining a unit-cam pair. In the illustrated embodiment, system  100  includes two columns  200 , each having three units  300  and three cams  400 . It is also contemplated that system  100  may include any number of columns  200 , each column  200  including at least two unit-cam pairs. In some embodiments, the teeth of units  300  can engage a detent mechanism that captures the unit after each input and resists movement of the unit until the next input. The detent may be spring-biased. 
       FIG. 2  is an exploded view of column  200  having units  300  and cams  400 . Each unit  300  has a top portion  310 , a bottom portion  320 , and an axial passage  302 . As used herein, the axial direction of columns  200  define the vertical direction (as well as related terms such as top/bottom and upper/lower), such that columns  200  rotate about a horizontal plane. These terms are used for ease of convenience and description, and are without regard to the orientation of system  100  with respect to the environment. For example, descriptions that reference a vertical direction is equally applicable when the system is in a horizontal orientation or off-axis orientation. Therefore the terms are not to be construed as limiting the scope of the subject matter herein. 
     Axial passages  302  are configured to receive an axle  210  such that each cam  400  is rotatable with respect to axle  210 . Each cam  400  has an axial passage  402  configured to receive top portion  310 . In column  200 , each cam  400  is coaxially associated with a unit  300 . Top portion  310  is positioned at least partially in an axial passage  402 , thus forming a unit-cam pair, and axle  210  passes through each axial passage  302 . 
     With reference now to  FIG. 3 , an illustrative unit  300  includes an axial passage  302 , a top portion  310 , and a bottom portion  320 . Bottom portion  320  defines a plurality of teeth  322 , the centerline of each tooth being offset from the centerline of each adjacent tooth by a tooth angle. In certain embodiments, a unit is operable between a plurality of incremental angular positions. In such embodiments, the number of incremental positions may be equal to the number of teeth. Each incremental position is offset from the previous incremental position by an increment angle which is defined as the tooth angle. For example, in system  100 , each unit  300  is operable between eight incremental positions P 1 -P 8 , each incremental position being offset from the previous by 45°. For example, at position P 4 , each tooth  322  occupies a space which is occupied by an adjacent tooth in either the adjacent incremental position P 3  or the adjacent incremental position P 5 . 
     Clockwise rotation generally increases the position number (which may be abbreviated as P+), and counter-clockwise rotation generally decreases position number (which may be abbreviated as P−). It is of course understood that “increasing” and “decreasing” the position number includes the transition between the first position and the last position. That is to say, in the illustrated embodiment, an incremental increase from position  8  results in position  1 , and an incremental decrease from position  1  results in position  8 . 
     In the illustrated embodiment, unit  300  has eight teeth, such that the tooth angle is 45°. In other embodiments, a unit may include more or fewer teeth. One of teeth  322  includes a missing portion, shown in  FIG. 3  as blank  325 . In the illustrated embodiment, blank  325  is positioned at the lower end of bottom portion  320 , though in other embodiments, blank  325  may be positioned at another location. The function of blank  325  is described below with respect to  FIG. 7 . 
     Top portion  310  is a hollow generally cylindrical body, and includes protrusions  312 . In the illustrated embodiment, the number of protrusions  312  is the same as the number of teeth  322 , and the centerline of each protrusion is offset from the centerline of each adjacent protrusion by the increment angle. In other embodiments, fewer protrusions may be used, such that the centerline of each protrusion is offset from the centerline of each adjacent protrusion by an integer multiple of the increment angle. Other configurations are also contemplated. 
     Top portion  310  defines top fly  314 , and bottom portion  320  defines bottom fly  324 . Top fly  314  is defined by a first arcuate segment of top portion  310  having an axial length greater than that of a second arcuate segment of the top portion  310 . Bottom fly  324  is substantially similar to top fly  314 , and is formed on bottom portion  320 . In the illustrated embodiment, flies  314 ,  324  each span three increments, or about 135°, and are positioned on opposite sides of the passage  302 . It is also contemplated that flies  314 ,  324  may be positioned at other locations, and may be of different configurations, as will be described below. 
     With reference now to  FIG. 4 , an illustrative cam  400  includes an axial passage  402  and a notch  422 . Axial protrusions  410  protrude from opposing sides of cam  400 , and are sized such that when cam  400  is positioned between two units  300  as shown in  FIG. 1 , the top fly  314  of the lower unit  300  is selectively engageable with the bottom fly  324  of the upper unit  300 . An example of the selective engagability of the flies is described below with reference to  FIG. 9 . 
     One of axial protrusions  410  has formed therein a plurality of recesses  412 , each configured to receive a protrusion  312 . In certain embodiments, axial protrusions  410  may not be positioned on cam  400 , and recesses  412  may be formed in the cam. The number of recesses  412  corresponds to the number of incremental positions, and a centerline of each recess  412  is offset from the centerlines of adjacent recesses by the incremental angle, although other configurations are also contemplated. When protrusions  312  are positioned in recesses  412 , cam  400  is rotationally coupled to unit  300 . When protrusions  312  are not positioned in recesses  412 , cam  400  is rotatable with respect to unit  300 . 
     With reference to  FIG. 5 , an illustrative fence  500  includes two prongs  520  coupled by a connecting portion  510 . Each prong  520  defines a plurality of protrusions  522  and recesses  524 . Protrusions  522  are configured to be received in a notch  422 , and recesses  524  are configured to receive a cam  400 . When all protrusions aligned with a notch, the fence is movable with respect to housing  192 . When the notch of at least one cam is not so aligned, fence  500  is not movable with respect to the housing. This interface of the notches with the locking fence provides a level of security that is not easily bypassed using non-invasive methods such as magnetic attraction or vibration. 
     In the illustrated embodiment, fence  500  is a vertically movable fence, configured to be movable in the vertical direction of columns  200  when all notches  422  are aligned with protrusions  522 . In other embodiments, a fence may be a radially movable fence, operable to move in the radial direction of cams  400  when all notches  422  are aligned with protrusions  522 . A horizontal fence may or may not include recesses  524 . 
     Fence  500  also includes interference portions, here illustrated as rods  521 . The interference portions are configured to engage any locking system known in the art. In an unlocked formation of columns  200 , the interference portions are movable with respect to housing  192 , such that a user is able to lock or unlock the locking system. In the illustrated embodiment, fence  500  includes two prongs  520  and two rods  521 , corresponding to the two columns  200 . In embodiments which include a different number of columns  200 , fence  500  may include a corresponding number of prongs  520 . 
     With reference now to  FIG. 6 , an illustrative carriage  600  includes fence channels  620 , cavities  630 , seats  640 , and reset channels  670 . Each fence channel  620  is configured to receive a prong  520  of fence  500 , such that fence  500  is substantially restricted to movement in a vertical direction. In embodiments which utilize a radially movable fence, fence channels  620  may be instead configured to restrict such a fence to movement in the radial direction. 
     Cavities  630  and seats  640  are each defined by upper walls  641  and lower walls  642 . Cavities  630  are configured to receive units  300 , and seats  640  are configured to receive cams  400 . Walls  641 ,  642  are positioned on carriage  600  such that cavities  630  have a height which is greater than the combined height of teeth  322  and protrusions  312 , and such that seats  640  have a height that is greater than the height of cam  400 . 
     Each seat  640  is configured to receive a cam  400 , such that cam  400  is at least partially positioned between an upper wall  641  and a lower wall  642 . Walls  641 ,  642  include arcuate segments configured to receive axial protrusions  410  extending from axial sides of cam  400 . In the illustrated embodiment, walls  641 ,  642  are each contiguous and arcuate, such that seat  640  is a single contiguous channel. In other embodiments, walls  641 ,  643  could be replaced by one or more protrusions, in which case seat  640  would be defined as a volume between a plane defined by one side of the cam and a plane defined by another side of the cam. 
     Reset channel  670  is configured to receive rod  172  of reset mechanism  170 . As previously noted, reset mechanism  170  includes a plurality of reset gears  700  corresponding to the plurality of units  300 , the operation of which will now be described. With reference to  FIG. 7 , as well as reference to  FIG. 1 , an example reset gear  700  is fixedly coupled to reset rod  172 . Reset gear  700  includes toothed portions defining teeth  722 , and untoothed portions, defined as portions having missing teeth  725 . 
     Reset gear  700  is positioned between units  300  which occupy the same horizontal plane such that each unit  300  can be engaged by reset gear  700  in a first set of incremental positions of the unit, and cannot be engaged by reset gear  700  in a second set of incremental positions of the unit. In the illustrated embodiment, each unit  300  can be engaged by reset gear  700  across seven incremental positions of the unit, and is not engaged by reset gear  700  in a single incremental position of the unit. The incremental position of each unit  300  in which it cannot be engaged by reset gear  700  is the home position of the unit, and is determined by the position of blank  325 . That is to say, when a unit  300  is not in a home position, teeth  722  engage teeth  322 , and when a unit is in a home position, teeth  722  pass through blanks  325 . 
     To reset each unit  300  to its respective home position, a user engages a rotating mechanism (not shown) configured to rotate rod  172 . Rotation of rod  172  also rotates each reset gear  700 , which in turn engages each unit  300  which is not in a home position. The rotating mechanism may be a knob, lever, wheel, or any other device configured to impart rotation. Once a sufficient number of rotations have been performed by reset gears  700 , each unit  300  is in a home position. At this point, each reset gear is rotated to a reset home position, defined as a position in which missing tooth  725  is aligned with blank  325 , such that units  300  cannot engage reset gears  700 . 
     In certain embodiments, reset gears  700  may be rotated to a reset home position manually by the user. For example, the rotating mechanism may have a first indicator which, when aligned with a second indicator, indicates that each reset gear  700  is in a reset home position. In other embodiments, reset gears  700  may be rotated to their home position automatically by the configuration of the rotating mechanism or another component of system  100 . For example, the rotating mechanism may bias reset gears toward the home position, such that once the rotating mechanism is not being operated by the user, the reset gears return to the home position. In certain embodiments, this may be achieved by a rotating mechanism having a lever operable across an angular range, and a gearing system configured translate the rotation of the lever across the angular range to a predetermined number of rotations of reset gears  700 . The lever may be biased to a lever home position, such that once a force is no longer being applied, the lever returns to the lever home position, which in turn returns reset gears  700  to a reset home position. 
       FIG. 8  illustrates a subassembly of system  100 , including a column  200 , fence  500 , and carriage  600 . Each prong  520  of fence  500  is inserted into a corresponding channel  650  such that rods  521  protrude vertically beyond a top surface of carriage  600 , and may also protrude from housing  192  (as can be seen in  FIG. 1 ). Fence  500  is positioned such that recesses  524  are substantially aligned with seats  640 . Column  200  is positioned in carriage  600 , such that units  300  and cams  400  are coaxially aligned, and such that each cam  400  is positioned in a seat  640 . 
     In a locked formation of column  200  wherein at least one notch  422  is not aligned with protrusions  522 , cam  400  prevents movement of fence  500  with respect to column  200 . In an unlocked formation of column  200 , wherein each notch  422  is aligned with protrusions  524 , fence  500  is movable with respect to column  200 , such that rods  521  can be removed from the disengaged from the corresponding locking system. In the unlocked formation, carriage  600  is also movable in the axial direction of columns  200 . A lifting mechanism (not shown) may have a first portion coupled to carriage  600 , and a second portion outside housing  192 . Operating the lifting mechanism moves carriage  600  in the axial direction of columns  200 . This in turn moves protrusions  522  into notches  422 , and separates each cam  400  from its respective unit  300 . The separation distance is greater than the height of protrusions  312 , such that protrusions  312  are no longer positioned in recesses  412 , and unit  300  is rotatable with respect to cam  400 . 
     With reference to  FIG. 9 , an example of selective engagement between units such as units  300  will now be described. Bottom unit  910  coaxial with and positioned below top unit  920 , such that the top fly  914  of bottom unit  910  selectively engages the bottom fly  924  of upper unit  920  at a fly interface  950 . Fly  914  includes engagement surfaces  915 ,  916 ; fly  924  includes engagement surfaces  925 ,  926 . 
     In the illustrated embodiment, there are eight incremental positions of units  910 ,  920 , and each fly  914 ,  924  has an angular span of three increments such that there is a two-increment play between fly  914  and fly  924 . As a result, units  910  and  920  are free to rotate with respect to one another across a free-rotation angle corresponding to two increments. 
       FIG. 9  illustrates three states of fly interface  950 , including a leading state (+), an in sync state (0), and a lagging state (−). In the illustrated embodiment, the play is two increments, such that interface  950  is operable between three states (+), (0), (−). It is also contemplated that the play may be only one increment such that the units are operable between two states, or the play may be three or more increments such that the units are operable between four or more states. 
     In leading state (+), top unit  920  leads bottom unit  910  by one increment. For example, if bottom unit  910  is in position P 5 , top unit is in position P 6 . In leading state (+), surface  915  of fly  914  is in contact with surface  925  of fly  924 . Thus, a one-increment counter-clockwise rotation of bottom unit  910  or a one-increment clockwise rotation of top unit  920  also causes a one-increment position change of the other unit. That is to say that in leading state (+), P+ of top unit  920  results in P+ of bottom unit  910 , and P− of bottom unit  910  results in P− of top unit  920 . A one-increment counter-clockwise rotation of top unit  920  or a one-increment clockwise rotation of bottom unit  910  results in a one-increment decrease in the state (which may be abbreviated as S−) of fly interface  950  to in sync state (0). That is to say that in leading state (+), P− of top unit  920  (or P+ of bottom unit  910 ) results in S− of fly interface  950 . 
     In lagging state (−), top unit  920  lags bottom unit  910  by one increment. For example, if bottom unit  910  is in position P 5 , top unit  920  is in position P 4 . In lagging state (−), surface  916  of fly  914  is in contact with surface  926  of fly  924 . Thus, a one-increment clockwise rotation of bottom unit  910  or a one-increment counter-clockwise rotation of top unit  920  also causes a one-increment position change of the other unit. That is to say that in lagging state (−), P− of top unit  920  results in P− of bottom unit  910 , and P+ of bottom unit  910  results in P+ of top unit  920 . A one-increment clockwise rotation of top unit  920  or a one-increment counter-clockwise rotation of bottom unit  910  results in a one-increment increase in the state (which may be abbreviated as S+) of fly interface  950  to in sync state (0). That is to say that in lagging state (−), P+ of top unit  920  (or P− of bottom unit  910 ) results in S+ of fly interface  950 . 
     In in sync state (0) top unit  920  is in sync with bottom unit  910 . For example, if bottom unit  910  is in position P 5 , top unit  920  is also in position P 5 . In in sync state (0), neither surface  915 ,  916  of fly  914  is in contact with the corresponding surface  925 ,  926  of fly  924 . A one-increment rotation in either direction of one unit  910 ,  920  results in a change in the state of fly interface  950 , but does not cause the other unit  910 ,  920  to rotate. The change in state corresponds to the direction of relative rotation of top fly  920  with respect to bottom fly  910 . That is to say that in in sync state (0), P+ of top unit  920  (or P− of bottom unit  910 ) results in S+ of fly interface  950  to leading state (+), and P− of top unit  920  (or P+ of bottom unit  910 ) results in S− of fly interface  950  to lagging state (−). 
       FIGS. 10   a  and  10   b  illustrate an example input system  1000  for causing rotation of units  300 . Input system  1000  includes a plurality of push-buttons  1010 ,  1020 ,  1030 , each operable to rotate units  1311 ,  1321 . Each push-button  1010 ,  1020 ,  1030  is independently slidingly mounted—for example through a hole formed in a faceplate—such that it can be forced into contact with a tooth of each unit  1311 ,  1321 , thereby rotating at least one unit by one increment. 
     Each pushbutton includes a first leg operable to engage a tooth of unit  1311  and a second leg operable to engage a tooth of unit  1321 . For example, pushbutton  1010  has a first leg  1011  operable to engage a tooth on the left side of gear  1311  and a second leg  1012  operable to engage a tooth on the left side of gear  1321 . Each pushbutton is operable between a home position and a thrown position, the positions being separated by a throwing distance. The throwing distance is such that operating the pushbutton rotates the corresponding units by an angle corresponding to one increment. Each pushbutton  1010 ,  1020 ,  1030  is provided with a biasing member configured to urge the pushbutton from the thrown position to the home position. 
     When pushbutton  1010  is forced into the thrown position, legs  1011 ,  1012  force the teeth in the throwing direction, thereby rotating units  1311 ,  1321 . Pushbutton  1010  is thus configured to rotate units  1311 ,  1321  by one increment in a clockwise direction. That is to say, pushing pushbutton  1010  causes P+ of units  1311 ,  1321 . When pushbutton  1010  is no longer being pushed inward, a biasing member (not shown) urges pushbutton  1010  outward to home position. Pushbuttons  1020  and  1030  operate in a similar manner, with the exception of the directions in which they are operable to rotate units  1311 ,  1321 . 
     Pushbutton  1020  is operable to engage a tooth on the right side of unit  1311  and a tooth on the left side of unit  1321 , such that pushing pushbutton  1020  rotates unit  1311  by one increment in a counter-clockwise direction and unit  1321  by one increment in a clockwise direction. That is to say, pushing pushbutton  1020  causes P− of unit  1311 , and P+ of unit  1321 . Pushbutton  1030  is operable to engage a tooth on the right side of unit  1311  and a tooth on the right side of unit  1321 , such that pushing pushbutton  1030  rotates units  1311 ,  1321  by one increment in a counter-clockwise direction. That is to say, pushing pushbutton  1030  causes P− of units  1311 ,  1321 . 
     In the illustrated embodiment, input system  1000  includes three pushbuttons, each configured to rotate both units  1311 ,  1321 . It is also contemplated that an input system may include additional, fewer, or alternative pushbuttons, which may be configured to operate one or more unit. For example, in a locking system having three columns, a pushbutton may be operable to rotate a unit in only one column, a pushbutton may be operable to rotate a unit in the outer columns, and a pushbutton may be configured to rotate a unit in each column. 
     While input system  1000  is shown as comprising a plurality of pushbuttons, certain embodiments utilize different input systems. For example, the input system could include one or more of sliders, levers, dials, knobs, joysticks or any other input system capable of adjusting the angular position of one or more unit. 
       FIG. 11  illustrates an example locking system  1100  having a reset mechanism  1124 , two columns  1210 ,  1220 , a pushbutton input system  1001 . Reset mechanism  1124  includes reset gears (not shown) similar to reset gear  700 . In the illustrated embodiment, a single reset gear is operable to reset both units in the row. For example, a single reset gear is operable to reset units  1311 ,  1321 . In other embodiments, one or more reset gear may be operable to reset a single unit. Reset mechanism  1124  is operable to set each column  1210 ,  1220  to a home position in which the missing tooth portions  1325  are axially aligned. 
     Each column  1210 ,  1220  includes three rows of unit-cam pairs. That is to say, column  1210  is rotatably mounted on an axle  1212  and includes units  1311 ,  1312 ,  1313  and cams  1411 ,  1412 ,  1413 ; column  1220  is rotatably mounted on an axle  1222  and includes units  1321 ,  1322 ,  1323  and cams  1421 ,  1422 ,  1423 . A plurality of fly interfaces define a location at which the bottom fly of an upper unit is selectively engageable with the top fly of a lower unit. For example, the bottom fly of unit  1311  is selectively engageable with the top fly of unit  1312  at fly interface  1214 . 
     In operation of system  1100 , each column  1210 ,  1220  is operable between a plurality of formations. The number of formations is a function of the number of unit-cam pairs in the column, the number of incremental positions of each unit, and the number of states of each fly interface. In the illustrated embodiment, these factors correspond to the number of rows, the number of gear teeth, and the amount of play available between adjacent units. In column  1210 , unit  1311  is operable between eight incremental positions, and fly interfaces  1214 ,  1216  are each operable between three states. As in the above-described embodiments, unit  1311  is operable between incremental positions P 1 -P 8 , and the fly interfaces  1214 ,  1216  are operable between leading state (+), in sync state (0), and lagging state (−). A formation of column  1210  can thus be succinctly described as (position of unit  1311 /state of fly interface  1214 /state of fly interface  1216 ), for example (1/+/+). 
     Columns  1210 ,  1220  are shown after having been reset to a home formation by reset mechanism  1124 . Missing tooth portions  1325  are positioned on each unit such that, in the home position of a column, the topmost unit is at a predetermined position, and either each fly interface is in leading state (+), or each fly interface is in lagging state (−). The home formation of column  1210  is defined as formation (1/+/+), wherein unit  1311  is at incremental position  1 , and fly interfaces  1214 ,  1216  are each in leading state (+). The home formation of column  1220  is defined as formation (1/−/−), wherein unit  1321  is at incremental position  1 , and fly interfaces  1224 ,  1226  are each in lagging state (−). While the home formation of system  1100  is system formation (1/+/+) (1/−/−), it is also contemplated that in other embodiments, the system home formation may be different. The home formation is defined by the relative positions of the blanks  1325 . 
     Input system  1001  comprises three rows, each of which is a substantial duplicate of input system  1000 . Although not shown in  FIG. 11 , each pushbutton includes two legs configured similarly to the legs of the corresponding pushbutton of input system  1000 . That is to say, pushbuttons  1040 ,  1070  are substantially similar to pushbutton  1010 ; pushbuttons  1050 ,  1080  are substantially similar to pushbutton  1020 ; pushbuttons  1060 ,  1090  are substantially similar to pushbutton  1030 . 
     In the illustrated embodiment, locking system  1100  includes two columns  1210 ,  1220 , each having three rows of unit-cam pairs. In certain embodiments, a locking system may have as few as one column of two rows. In other embodiments, a locking system includes at least two columns and at least two rows. In some embodiments, not all columns include the same number of rows. 
     With respect to  FIGS. 11 ,  12   a , and  12   b , the operation of system  1100  during code entry will now be described. Each of  FIGS. 12   a  and  12   b  illustrate from left to right: the home formations of columns  1210 ,  1220 ; changes to the formations caused by a first pushbutton press; the formations of columns  1210 ,  1220  after the first pushbutton press; changes to the formations caused by a second pushbutton press; the formations of columns  1210 ,  1220  after the second pushbutton press. 
     In  FIG. 12   a , column  1210  begins in home formation (1/+/+), and column  1220  begins in home formation (1/−/−). The code to be entered in  FIG. 12   a  is a first code “1-2”. The first digit of the first code is entered by pressing pushbutton  1010 . As described above, pressing pushbutton  1010  rotates units  1311 ,  1321  one increment in the clockwise direction such that the position of each unit  1311 ,  1321  is increased from P 1  to P 2 . Fly interfaces  1214 ,  1216  each begin in leading state (+), and P+ of unit  1311  therefore causes P+ of units  1312 ,  1313 . Fly interfaces  1224 ,  1226  each begin in lagging state (−), and P+ of unit  1321  therefore causes S+ of fly interface  1224 . After the first pushbutton press, the system formation is (2/+/+) (2/0/−). 
     After pushbutton  1010  has been pressed, the second digit of the first code is entered by pressing pushbutton  1020 . Pressing pushbutton  1020  results in P− of unit  1311  and P+ of unit  1321 . Fly interface  1214  begins in leading state (+); P− of unit  1311  therefore only causes S− of fly interface  1214 . Fly interface  1224  begins in in sync state (0); P+ of unit  1321  therefore causes S+ of fly interface  1224 . Entry of the first code thus results in a system formation of (1/0/+) (3/+/−). 
     In  FIG. 12   b , column  1210  begins in home formation (1/+/+), and column  1220  begins in home formation (1/−/−). The code to be entered in  FIG. 12   a  is a second code “2-1”. The first digit of the first code is entered by pressing pushbutton  1020 . Pressing pushbutton  1020  causes P− of unit  1311  and P+ of unit  1312 . Fly interface  1214  begins in leading state (+); P− of unit  1311  therefore causes S− of fly interface  1214 . Fly interface  1224  begins in lagging state (−); P+ of unit  1321  therefore causes S+ of fly interface  1224 . After the first pushbutton press, the system formation is (8/0/+) (2/0/−). 
     After pushbutton  1020  has been pressed, pushbutton  1010  is pressed. Pressing pushbutton  1010  causes P+ of units  1311 ,  1321 . Fly interface  1214  begins in in sync state (0); P+ of unit  1311  therefore causes S+ of fly interface  1214 . Fly interface  1224  begins in in sync state (0); P+ of unit  1321  therefore causes S+ of fly interface  1224 . Entry of the second code thus results in a system formation of (1/+/+) (3/+/−). System  1100  is therefore sequence-dependent, as a combination 1-2 is can be differentiated from a combination 2-1. Furthermore, pressing the same button (or entering the same input in other types of user input mechanisms) more than once also changes the column formation. As will be appreciated, this means that system  1100  can allow a user to utilize multiple throws of a single button while still creating a unique code. For example, the system is able to differentiate between a combination of 1-2 versus 1-1-2 or 1-2-2. In the illustrated embodiment, system  1100  is capable of differentiating at least eight consecutive presses of the same button, due to the eight incremental positions of units  300 . 
     Because system  1100  is both sequence-dependent and capable of distinguishing between duplicate entries, the number of unique codes available to the user is greatly increased. By selecting the proper number of columns and rows, codes of any length can be provided for. 
     Additionally, system  1100  is capable of being recoded without disassembly. An illustrative recoding operation will now be described with reference to  FIGS. 1 and 8 . The recoding operation begins with resetting columns  200  to the home position by operation of reset mechanism  170 . The current code is then entered, such that columns  200  are in the unlocked formation, and cams  400  are vertically movable with respect to fence  500 . 
     The carriage is then lifted by the user, for example by way of a lifting member (not shown) which is coupled to carriage  600  and extends out of housing  192 . If the proper code has not been entered, protrusions  522  prevent vertical movement of cams  400 , which in turn prevents vertical movement of carriage  600 . If the proper code has been entered such that notches  422  are aligned with protrusions  522 , carriage  600  is free to be lifted. Lifting carriage  600  moves protrusions  522  into notches  422 , and separates each cam  400  from its respective unit  300 . The separation distance is greater than the height of protrusions  312 , such that protrusions  312  are no longer positioned in recesses  412 , and unit  300  is rotatable with respect to cam  400 . 
     Columns  200  are again reset to home formations by operation of reset mechanism  170 . Notches  422  remain engaged with protrusions  522 , such that cams  400  remain aligned with the protrusions. 
     Once columns  200  have been reset, a new code is entered, such that columns  200  are moved into a new unlocking formation. Carriage  600  is lowered, protrusions  312  are received in recesses  412 , and the system has been recoded. Subsequent entry of the new code (after resetting columns to home formations) causes notches  422  to again become aligned with protrusions  522  such that the system is unlocked. 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the inventions are desired to be protected. It should be understood that while the use of words such as preferable, preferably, preferred or more preferred utilized in the description above indicate that the feature so described may be more desirable, it nonetheless may not be necessary and embodiments lacking the same may be contemplated as within the scope of the invention, the scope being defined by the claims that follow. In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary. 
     Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.