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CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Patent Application No. 61/208,680, filed Feb. 25, 2009. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates generally to electronically or electronically controlled locks, such as door locks. More particularly, it concerns improvements in control mechanisms located between handle input, and latch or bolt outputs of such devices. 
     There is need for simplicity, reliability, and effectiveness of such control mechanisms, including improvements in structure, functioning and results associated with operation of such mechanisms. 
     SUMMARY OF THE INVENTION 
     It is a major object of the invention to provide improvements meeting the above needs. Basically, the invention is embodied in the following, in combination: 
     a) an elongated housing having input code selectors on the housing, to enable the door locking and/or unlocking via a locking element, 
     b) a locking handle protruding from the housing, 
     c) a coupling in the housing having parts that interfit to enable force transmission between said handle and element, 
     d) and first means responsive to code selection to control coupling of said parts. 
     As will be seen, said means include an electronic motor in the housing to effect controlled displacement of one or more of said parts. 
     Another object include provision of second means to compensate for interfit misalignment of said parts and to automatically overcome said misalignment. 
     That second means may advantageously include a spring or springs biasing at least one of said parts to interfit another of said parts in response to relative rotation of said parts. 
     Another object is to provide means to resist handle turning at selected handle turn angles, and also allow handle turning in response to override force transmitted via handle turning, for handle re-positioning relative to the housing. 
     A further object include provision of handle force resisting structure that includes a rotor, an elongated spring, and at least one set of interengaged balls that transmit spring force to the rotor with mechanical advantage. 
     Yet another object is to provide coupling parts, and a spring or springs biasing at least one of said parts to interfit another of said parts in response to relative rotation of said parts. One of such springs may be compliant fork-shaped leaf spring urging the coupling against tips of the pins. 
     A further object is to provide means to compensate and overcome misalignment of coupling pins and slots in a coupler. 
     An additional object is to provide means to allow release of a battery cover, including a one-piece elongated shifter basically movable in response to key input turning of a control rotor. 
     Also, the housing may include a battery compartment lid, there being a retention fastener, an override bracket blocking access to the fastener from the exterior, and having a position in which such access is unblocked, there being means blocking movement of the bracket to said position in response to unauthorized such access. 
     An additional object is to provide apparatus multiple improvements as disclosed herein. 
     These and other objects and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following specification and drawings, in which: 
    
    
     
       DRAWING DESCRIPTION 
         FIG. 1  is a perspective view of lock apparatus incorporating the invention; 
         FIG. 2  is a diagram showing a system of elements carried within the apparatus housing, to effect operation of the lock in response to handle turning; 
         FIG. 3  is a perspective view of a handle re-positioning clutch mechanism; 
         FIG. 4  is an axial section taken through  FIG. 3 ; 
         FIG. 5  is a view like  FIG. 1 , but with the handle turned to show length direction, the same as housing length; 
         FIGS. 6-8  show coupling mechanisms; 
         FIG. 9  shows a configuration of motion translation elements between the coupling and a dead latch; 
         FIG. 10  is a view like  FIG. 9 , but showing shifted position of elements; 
         FIG. 11  is a side view showing installation of an override bracket for blocking access to a fastener that secures a battery compartment cover plate; 
         FIG. 11A  is a side view of the mechanism shown in  FIG. 11  with the cover plate fastener unblocked; 
         FIG. 12  is a frontal view of  FIG. 11  elements showing the cover plate fastener blocked; 
         FIG. 13  is a perspective view of the override bracket; 
         FIG. 14  is a perspective view of the battery compartment cover plate; 
         FIG. 15  is a perspective view of a crank cover; 
         FIG. 16  shows Hall Effect mechanism; and 
         FIG. 17  is a schematic view of override bracket and key cylinder cam. 
     
    
    
     DETAILED DESCRIPTION 
     Referring first to  FIGS. 1 and 5 , it shows the lock assembly in the form of an elongated housing  100  with a key pad  101  including multiple coding selectors at  102  on the housing outer side  103 . A handle  104  is carried for turning as between  FIG. 1  and  FIG. 5  positions. Batteries within the housing are accessible after removal of lid or cover plate  105 , in response to insertion of a key into the housing via slot  106  and turning of the key, which permits the removal of the cover plate. 
     Referring to the system schematic diagram seen in  FIG. 2 , it shows handle input displacement, such as turning, at  107 , to a slip clutch assembly  108 . The assembly shown includes a shaft  1 , the slip-mechanism  110  allowing handle slip, and output pins  5 . Referring to the  FIGS. 3 and 4 , slip clutch assembly  108  includes a clutch plate  2 , two compression springs  3 , four steel balls  4 , two output pins  5 , an override set screw  6   a , and pins  3   d  securing springs  3  in vertical holes  3   a . Handle  104  connects to the top of output shaft  1 . A coupling mechanism  111  (see  FIG. 2 ) couples the output pins  5  to the drive mechanism  126  that finally drives the deadbolt or dead latch device. A latch device is shown at  112  in  FIG. 2 . The slip clutch assembly  108  seen in  FIG. 2  is designed to allow slippage of the handle  104  relative to the drive mechanism  126  at a torque lower than would be required to destroy or damage the drive mechanism but a torque significantly higher than normally required to operate a dead latch or deadbolt device through drive mechanism  126 . In such capacity, the slip mechanism  110  acts as a mechanical “fuse” if for instance the deadbolt is “jammed” or misaligned with its mating strike plate. As shown in  FIG. 4 , the clutch plate  2  may have ball detent pockets  113  disposed radially every 45 degrees, about the axis of plate rotation. The output shaft  1  has a plurality (two, as shown) of vertical holes  3   a  drilled to house long compression springs  3 . These holes are intersected by holes  3   b  at the bottom of the output shaft  1  radiating out from output shaft  1  centerline or axis  1   a . The compression springs push downwards against steel balls oriented to push outwards against a second set of steel balls at a shallow pressure angle  3   c . The second set of steel balls protrude out of the holes in the output shaft  1  and engage detent pockets  113  in the clutch plate  2 . In this way, the orientation of the balls relative to their mating balls allow the springs to be located in perpendicular relation to the necessary direction of final force application for the clutch and situated in an orientation where more space is available. Note that the direction of spring elongation is parallel to the length direction of axis  1   a . Furthermore, the shallow pressure angle  3   c  and friction between the ball pairs creates a mechanical advantage that allows a lower spring force to create a higher clutching torque. This allows the slip clutch assembly to be more compact and lower cost than would otherwise be feasible.  FIG. 4  shows a section view of the slip clutch assembly  108 . 
     Besides acting as a mechanical fuse, the slip clutch assembly  108  provides other benefits. For example, downward extending tail section  104   a  ( FIGS. 1 and 11 ) may be added at the end of handle  104 . With the battery cover plate  105  removed, clearance is provided between tail section  104   a  and housing  100  and the slip clutch assembly allows the handle to be rotated, past where the cover plate was, to a detent position 90 degrees from the normal operating position of the handle as shown in  FIG. 5 . This allows the unit to be shipped in a compact configuration with the handle already attached. This in turn minimizes packaging size/cost and freight charges. With cover plate  105  in place, tail extended section  104   a  prevents unwanted repositioning of handle  104 . 
     Furthermore, the slip clutch assembly  108  allows the unit to be “rehanded” in the field, quickly and easily. For instance, some applications require the handle to point right and others require that it point left. When the unit is removed from packaging, the handle can be rotated two detent positions clockwise (45 degrees plus 45 degrees) if the handle needs to point left or two detent positions counter-clockwise (45 degrees plus 45 degrees) to point right. Thus, the unit can be “rehanded” any time in the field if there is a desire to remount the unit for re-handling. 
     In another aspect of the invention, a coupling mechanism is provided to couple the handle to drive mechanism  126 , as via the slip clutch assembly  108 . See for example in  FIG. 2 , coupler  13  receiving input via pins  5  of the slip clutch assembly  108 , and transmitting rotary drive at  125  to drive mechanism  126 . Such mechanism effects such coupling in response to operation of an electrical motor  6  controlled by the selectors  102  of the keypad  101 . In this regard, means is provided to compensate for input misalignment of the coupling parts (typically pins  5  and slots  5   a  in coupler  13 , such misalignment typically being rotary), and to automatically overcome such misalignment to enable effective coupling, for operation of the latch device  112  by the handle. 
     As shown in  FIGS. 6-8 , a keypad operated gear motor  32  drives a cam  7  that pushes on a cam follower assembly  8 . The cam follower assembly  8  pivots around a mounting pin  9 . The cam follower assembly  8  consists of a body  10 , a cam follower pin  11 , and a fork shaped leaf spring  12 . Body  10  includes a first end and a second end, wherein cam follower pin  11  is disposed on the first end of body  10 , and wherein fork shaped leaf spring  12  is disposed on the second end of body  10 . The fork shaped leaf spring  12  pushes against a coupler  13  that is biased against the fork shaped leaf spring  12  with a light compression spring  12   a . The spring constant and preload of the leaf spring  12  is significantly higher than that of the compression spring. Referring to  FIGS. 6 and 16 , when the high side lobe  7   a  of the cam  7  pushes down against the cam follower pin  11 , the cam follower assembly  8  pivots around the pin  9 . The fork shaped leaf spring  12  pushes against the coupler  13  causing it to move upwards until the output pins  5  engage slots  5   a  in the coupler  13 . With the handle in its rest position 3 or 9 O&#39;clock, the coupler pins  5  are aligned with slots  5   a  in the coupler  13  and the fork shaped leaf spring  12  only has to deflect a minute amount to compress the compression spring which biases the coupler  13  downwards (as oriented in  FIG. 6 ). If for instance a user has the handle turned while operating the coupler and the coupler pins  5  do not align with the slots in the coupler  13 , the fork shaped leaf spring  12  bends more and pushes the coupler  13  against the tips of the coupler pins  5 . Once the handle has positioned to the 3 or 9 O&#39;clock position (as in  FIG. 1 ), the force from the fork shaped leaf spring  12  will push the coupler pins  5  into the coupler slots  5   a . Thus, the fork shaped leaf spring  12  provides enough rigidity to overcome the compression spring but enough compliance so the mechanism does not lock up or stall with the handle moved out of a 3 or 9 O&#39;clock position. 
     In the event that the unit&#39;s batteries die at a position where the lock is left in an unlocked position, the unit handle can be removed and the override set screw  6   a  tightened until the coupler  13  is no longer engaged to the coupler pins  5 . Thus the unit is returned to a locked position. The compliance of the fork shaped leaf spring  12  allows this to happen without permanent damage to the unit. When the dead batteries are replaced the override set screw  6   a  can be backed off to allow normal operation. 
     Referring to  FIGS. 6 ,  8  and  9 , the coupler  13  slides axially on a square shaped shaft  13   a  that keys either to an input gear  14  or to a butterfly shaped cam  15  depending on whether the unit will operate a deadbolt or dead latch, respectively. The square feature of the shaft  13   a  allows coupler  13  to translate up and down, as oriented in  FIG. 6 , and also to transmit torque to shaft  13   a  through its entire range of motion. 
     The alternative deadbolt mechanism ( FIG. 8 ) consists of three gears, an input gear  14 , an idler gear  16 , and an output gear  17 . The output gear  17  has a rectangular opening  17   a  that accepts a sheet metal “tailpiece”  17   b . The “tailpiece” couples the output gear  17  to the deadbolt device (not shown). A small magnet  18  holds the tailpiece in place while the unit is being assembled to the door. 
     Typically, deadbolts require two directions of output to operate the bolt. One direction of rotation of handle  104  locks the deadbolt while the opposite direction of rotation unlocks the deadbolt. The illustrated gear train mechanism in  FIG. 8  provides two directions of output rotation for two directions of handle rotation. 
     In a dead latch application as shown in  FIG. 9 , the required direction can be clockwise or counterclockwise depending on whether door lock is right or left handed. Therefore, the dead latch version needs to be able to rotate in either direction, but only in one direction at a time. 
     Referring to  FIG. 9 , the butterfly shaped cam  15  keys to the coupler  13 . The butterfly shaped cam  15  interacts with a slider crank  19 . As oriented in  FIG. 9 , the slider crank is biased upward by two compression springs  19   a . When the butterfly shaped cam  15  is coupled to the handle through the coupler  13 , either direction of handle rotation causes the slider crank  19  to be moved downward due to the butterfly shaped cam  15  dual lobe symmetry. The slider crank  19  has an elongated slot  20  that receives a pin  21  from an output shaft  22 . In  FIG. 9 , translation of the slider crank  19  in a downward direction causes clockwise rotation of the output shaft  22 . The output shaft  22  couples to a dead latch through a tailpiece  22   b  inserted into its inner cross shape  22   a . As with the dead bolt version, a small magnet  18  in the cross shape  22   a  helps hold the tailpiece in place during assembly. Furthermore, a user can insert a straight blade screwdriver into cross shape  22   a  and rotate output shaft  22  clockwise against the force of the two compression springs until the output shaft  22  goes “over center” and the pin  21  ends up on the opposite side of the slot  20  as shown in  FIG. 10 . 
     In this case, translation of the slider crank  19  downward in  FIG. 10  causes counterclockwise rotation of the output shaft  22 . In this way, the unit can be quickly and easily adjustably rehanded for right or left hand doors. This provides cost and logistics advantages to have one configuration work for either handling requirement. 
     As illustrated above, the deadbolt and dead latch versions share most parts and only differ in the last several parts in their respective mechanism chains. The relatively small differences are adapted to by the different output motion requirements. However, sharing of most components has a positive effect on keeping cost and complexity down. 
     As with all locks, security is of utmost concern. The present device has a battery cover plate  105  ( FIG. 1 ) that allows access to the battery compartment. With the batter cover plate off, this compartment also allows access to two mounting screws ( 109 ) at the bottom of elongate housing  100  ( FIG. 12 ) for mounting the housing to a door. With these screws removed, the elongate housing can be unclipped from a hook (not shown) that holds the top of the housing to the door. By using such method of securing the unit to a door, all fasteners are hidden. For many architects, this is an important feature. It is therefore of importance that access to the housing mounting screws ( 109 ) that are accessible via the battery compartment be controlled to maintain security. 
     Referring to  FIGS. 11 and 14 , the battery cover plate  105  has a sheet metal tang  23  that is screwed to the elongate housing  100  by a screw  23   a  for securing the cover plate to the housing. Access to screw  23   a  is provided by a small hole  24  in the top of the housing. Referring to  FIGS. 11 and 13 , override bracket  25  has a feature  26  that blocks access to the battery cover plate screw  23   a  through this small hole  24 . Referring to  FIG. 1 , the override bracket  25  interacts with a cam  106   a  of the key cylinder. Rotating the key to the unlocked position shown biases override bracket  25  downward against spring  29  and accomplishes two things: 1) a cam surface  27  on the back of the override bracket  25  pushes down on the cam follower pin  11  of the cam follower assembly  8  coupling the handle to output shaft  13   a , and 2) the override bracket  25  moves downward (arrow L in  FIG. 11 ) to a position where feature  26  no longer blocks the battery cover plate screw  23   a  and thus allows the battery cover plate to be removed (see  FIG. 11A ). 
     If a person were to insert a small sharp object such as a pick into hole  24 , he might use two picks to try and “walk” the override bracket  25  down in small increments eventually allowing access to the battery lid screw and compromising security. 
     The override bracket  25  is normally biased upward towards the top and towards the front of the unit by two compression springs  29  and  28 , respectively ( FIG. 11 ). Referring to  FIGS. 11 and 15 , a small protruding feature  30  on crank cover  31  normally (such as when someone is using a key) does not interact with the override bracket  25 . However, when someone necessarily pushes on the override bracket  25  against spring  28  through the cover plate access hole  24  to “pick” the unit, override bracket  25  moves away from the front of the unit slightly until its movement is blocked by protruding feature  30  on crank cover  31 . This prevents to override bracket from being “walked” down to allow access to the batter cover plate screw. 
     Accordingly, the apparatus is configured to include a battery compartment cover plate having a retention fastener, an override bracket that blocks access to the fastener from the exterior and having a position in which such access is unblocked; and a means for blocking movement of the override bracket in response to unauthorized access. 
     Hall Effect cam position sensing is also provided. See  FIG. 16 . Gear motor  6  drives cam  7 . The cam  7  has a “high” lobe  7   a  and a “low” lobe  7   b . Upon rotation of the cam by motor  6 , the high lobe pushes on cam follower assembly  8  as described above, which couples the handle to the output shaft. Upon further rotation of the cam by the motor, the cam “low” lobe  7   b  aligns with follower assembly  8 . At that point, the handle becomes uncoupled to the output. It is therefore important to control the position of the cam  7  such that either the “high” or “low” lobe is aligned with cam follower assembly  8  when the motor stops. For this purpose, the cam  7  includes a body portion  7   c  that extends axially from lobes  7   a ,  7   b , wherein the surface of body portion  7   c  houses south and north pole oriented magnets  34   a,b  that interact with a Hall Effect unit  35 . The Hall Effect unit senses the magnetic flux of the magnets and “communicates” with microprocessor  80  such that the cam&#39;s position can be correctly detected. 
     The Hall Effect unit is powered via an I/O port of the microprocessor.

Summary:
Door lock apparatus, comprising in combination an elongated housing having input code selectors on the housing, to enable door locking and/or unlocking via a locking element, a locking handle protruding from the housing, a coupling in the housing having parts that interfit to enable force transmission between the handle and element, and a coupling mechanism responsive to code selection to control coupling of the parts.