You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION 
     This invention is concerned with security of lockers, safes, desks, file cabinets or other storage devices assigned for temporary or long-term use, especially lockers. In particular, the invention relates to an electronic lock for a locker having a standard three-hole locker door prep layout, to replace a standard key or combination lock fitting the same locker door. The lock of the invention is compact, manually operated (although embodiments could be automatically operated) to release a locker door latch when the electronic access control is properly accessed. 
     Electronic locks are well known. For example, hotel safes for temporary use by guests have included digital locks with keypads for use by the guest. In some cases, the guest was able to select his own combination for the digital lock. In other cases, a combination sequence has been pre-assigned to electronic locks, with the combination sequence not under the control of the user. 
     U.S. Pat. Nos. 5,886,644 and 5,894,277, owned by the assignee of the present invention, describe electronic locker locks to fit a standard three-hole door prep layout as well as other doors. The electronic locks described in those patents are comprised of two housings, mounted at front and back of the door and electronically connected through the center hole of the three-hole door prep layout, and they included an electromagnetically-driven latch, retracted automatically by the lock device when the proper code was entered by a user, either via a keypad or an electronic ID device such as an iButton. Both patents are incorporated herein by reference. 
     The following additional U.S. patents are believed to have some relevance to this invention: U.S. Pat. Nos. 5,373,718, 5,321,963, 5,223,829, 5,153,561, 5,033,282, 5,021,776, 5,020,345, 4,967,305, 4,931,789, 4,887,445, 4,665,397, 4,568,998, 4,495,540, 4,243,256, 3,878,511, 3,831,065, 3,754,213, 3,754,164 and 3,753,164. 
     There has been a need for an electronic lock operated by an electronic identification device of relatively inexpensive construction, particularly for lockers but with more versatility as to use on various standard designs, modularity as to assembly and opposite-hand use, easy programmability and convenience and simplicity to the user. These are the goals of the present invention described below. 
     SUMMARY OF THE INVENTION 
     The invention addresses these goals with a low profile and compact electronic unit that, in a preferred application, fits the standard three-hole locker door prep layout of a locker door. The compact electronic locking device fits on the front side of the door and in one embodiment has a knob or handle that can rotate a latch at the back side of the door when such manual rotation is permitted by the lock electronics. The electronic lock comprises a single electronic lock housing which is positioned on the outside of the door; at the back side of the door, i.e. the opposite side of the three-hole door prep, is either a latch driven directly by a driver extending back from the electronic unit, or a mechanical unit with a latch, sometimes known as a built-in lock for lockers, and this unit is driven by the driver extending back from the handle in the electronics housing. It is important that all electronics are contained in a single electronics housing at the front side of the locker door, with mechanical features, e.g. the latch or a built-in deadbolt lock device, behind the door and connected to the driver. 
     In one preferred embodiment particularly adapted for a locker with a latch, the electronic lock of the invention includes a single compact electronic lock housing with a keypad for entry of codes by a user, the housing adapted to be positioned on the front panel of the locker door having a standard three-hole locker door prep arrangement. The lock driver extends from the back side of the electronics housing and is adapted to engage with and operate a locker latch device on the inside of the locker door, and with a knob or handle on the outside housing for operating the lock manually to rotate the driver and retract the latch device when permitted by the electronics. The latch device may also be operated by an electromagnetic or motorized mechanism in the outside housing, rather than manually. The driver extends through the middle hole of the three-hole lock receiving pattern on the door, with provision for fasteners extending through the upper and lower holes of the three-hole pattern to secure the electronics housing to the door. A battery compartment preferably is included in the housing to operate the electronics and in a preferred embodiment is accessible from the exterior when the housing is secured against a locker door. 
     The invention thus provides a compact, easily used electronic lock requiring low power in the case where unlatching is done manually, easily fitted to a locker door with standard three-hole pattern and advantageously used to replaced a keyed or combination lock. These and other objects, advantages and features of the invention will be apparent from the following description of a preferred embodiment, considered along with the accompanying drawings. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 and 2  are side and front elevation views showing one embodiment of an electronic lock device, with keypad, adapted particularly for lockers. 
         FIG. 3  shows in perspective a variation of  FIGS. 1 and 2 . 
         FIGS. 4 and 5  are front elevation views showing another variation of the electronic lock of  FIGS. 1 and 2 , showing locked and unlocked positions, respectively. 
         FIG. 6  is a side elevation view showing an electronic lock housing similar to that of  FIGS. 1 and 2 , with a driver extending back from a handle of the housing, to operate a latch mechanism at the back side of a locker door. 
         FIG. 7  is a perspective view showing a rear latch-operating mechanical unit which can be installed at the back side of a door having the electronic lock unit of  FIG. 6 . Such a latch unit is known in the industry as a built-in lock. 
         FIGS. 8 and 9  are front elevation views showing locker locks similar to  FIGS. 1 and 2  but with an electronic code reader rather than a keypad. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1  shows a lock  10  particularly adapted for locker doors having a standard three-hole locker door prep layout. As is well known, the three holes are aligned vertically, with fastener holes at top and bottom and a larger center hole for a key cylinder or a combination lock or an appropriate form of lock with a handle to release a latch. In the case of U.S. Pat. No. 5,886,644 referenced above, the center hole was used for electrical connection between a front housing and a rear housing. In the lock device of  FIG. 1  herein the center hole can accommodate a rotating latch  12 , which can be attached to the remainder of the lock via a spindle or driver (not shown in  FIG. 1 , see  FIG. 6 ) after a lock housing  14  is installed on the front side of the door. As indicated, machine screw studs  16  can be provided extending back from the back side  18  of the housing  14 , for securing the lock to the door using nuts (or threaded holes can be provided,  FIG. 3  below, to receive machine screws through the door).  FIGS. 1 and 2  show a manually operated handle  20  of desired form, which can be a lever as shown, at the front of the lock to rotate the latch. The lock  10  has internal electronics, supported by batteries carried in the housing, and functions internally similarly to the lock described copending application Ser. No. 11/809,172, incorporated by reference. Like the lock of the copending application, the lock  10  has a terminal  22 , i.e. a set of contacts  22  for engagement by an electronic key device, for both supplying jump power to the lock when its internal batteries are low, and entering a master code to access (unlock) the lock. Such a terminal and manager or master key device are also described in application Ser. No. 12/072,557, filed Feb. 26, 2008 and in U.S. Pat. No. 7,336,150. The disclosures of the application and the issued patent are also incorporated herein by reference. As described in the referenced patent and applications, the manager&#39;s key device allows a manager or supervisor to apply the key device to simultaneously jump power to the lock  10  and enter a master code to open the lock. 
     A keypad  24  preferably is provided on the lock device  10 . Other electronic code input devices, such as a contact for an iButton key such as shown in U.S. Pat. No. 7,336,150, could be provided, as discussed below, or proximity or other wireless input or Weigand or mag stripe card readers. 
     The electronic locker lock  10  of the invention preferably operates in a manner generally similar to that described in the above-referenced U.S. Pat. Nos. 5,886,644 and 5,894,277, both describing locker locks, except that here the locker lock is moved from locked to unlocked position and vice versa by operating the handle  20 . As explained in those prior patents, the user of the locker lock, usually for temporary use, approaches the locker in an unlocked condition. The user enters a code, which may be selected by the user in the case of a keypad  24  as shown, after placing his valuables in the locker and closing the door. This has the effect of retracting an internal blocking device which has been engaged against a ridge or in a notch on the rotatable member or driver within the lock. The retraction of the blocking device allows the user to turn the knob or handle to extend a bolt and put the lock in the locked condition. When moved to the locked position, the internal member or driver is retained in this position by the blocking device again engaging with the driver, preferably in a notch dedicated to the locked position. Later, when the user again approaches the locker to retrieve his valuables, the access code is again entered, again causing the blocking device to be retracted and enabling the user to rotate the knob to put the lock in the unlocked condition. Again, the blocking device engages in the unlocking notch. The engagement in the notch can be via a spring, with retraction being only momentary (by a miniature motor or solenoid), or both retraction and engagement of the blocking device can be performed by a solenoid or miniature motor. 
       FIG. 3  shows that the locker lock  10  can have threaded holes  25  to receive machine screws inserted from the back of the door, rather than the studs shown in  FIG. 1 . 
       FIGS. 4 and 5  show further variations. A lock  10   b  of  FIGS. 4 and 5  has a lever-type or toggle-type handle  20   b , limited in arc of movement and with a visual indication of whether the lock is in the locked or open position. The handle could be a longer lever, as for handicapped use. In  FIG. 4  the access handle is in the horizontal position, exposing a flat area  26  which may be red in color, for example, indicating locked status. In  FIG. 5  the handle has been shifted clockwise to the limit position, exposing a different area  28  under the handle&#39;s path, which may be green, for example, indicating unlocked status. The color areas  26  and  28  are revealed through a window in the handle device. 
       FIG. 6  shows a lock  10   a , which may be similar to the lock of  FIG. 3  or  FIGS. 1 and 2 , but having at its back side, extending from a midpoint between the studs  16  so as to pass through the center hole of a three-hole locker door prep pattern, a spindle or driver  30 . The driver  30 , which can be square, rectangular, triangular, splined or in other configurations, is engaged with a latch simply affixed to the driver  30  as in  FIG. 1 , or a latch mechanism of a suitable type such as shown in  FIG. 7 , the mechanism being secured to the back side of the door. 
       FIG. 7  shows, somewhat schematically, a mechanical latch or deadbolt unit  32 , essentially of the type called in the industry a built-in lock for lockers. This can be either a deadbolt unit or a spring latch unit, a deadbolt being shown here. The unit  32  is made with the standard three-hole pattern and can be secured using the same studs  16  extending from the lock unit  10  or  10   a , or with machine screws that are inserted from the back, first through holes  33  in the built-in unit  32  and then through the door panel and into threaded holes provided in the housing  14  of the lock  10  or  10   a , as disclosed above. At the center position of the built-in deadbolt lock or latch unit  32 , i.e. at the position of the large center hole of the three-hole pattern, is a rotation member  34  having a driver receiving hole  36  shaped according to the shape of the driver  30  extending back from electronic lock unit  10 ,  10   a.    
     The built-in deadbolt or latch unit  32  is strictly mechanical, and is a substitute for a simple rotational latch such as shown at  12  in  FIG. 1 , for a situation in which a spring latch or a sliding deadbolt is appropriate. 
       FIGS. 8 and 9  show another embodiment of a locker lock  40 ,  42  to fit the standard three-hole locker door pattern as in  FIGS. 1 and 2 . The lock is similar to the lock of those figures, except in not having a keypad. Instead, the locks  40  and  42  have an electronic code reader  44 ,  46 . The code reader  46  on the lock of  FIG. 9  is an iButton reader, which reads the code when an iButton “key” held by a user is touched to the reader  46 . This is similar to the locker door lock described in U.S. Pat. No. 5,886,644 referenced above, but the lock of that patent had an electric retraction for retracting the bolt or latch, rather than the manual retraction of the locks shown in  FIGS. 8 and 9 , and in addition that locker door lock had a two-housing construction, with the locker door sandwiched between the inner and outer housings. 
     In  FIG. 8  the reader  44  is an infrared or other wireless technology reader. Both locks  40  and  42  have a terminal  22 , as described above, for accessing the lock by a manager or attendant, and for providing power to the lock if the lock&#39;s battery is low. Also as in the previously described locks, the back of the lock can have a driver to operate a mechanical latch or bolt unit such as shown in  FIG. 7 , or it can have a swivel latch directly attached as in  FIG. 1 . 
     The above described preferred embodiments are intended to illustrate the principles of the invention, but not to limit its scope. Other embodiments and variations to these preferred embodiments will be apparent to those skilled in the art and may be made without departing from the spirit and scope of the invention as defined in the following claims.

Summary:
A locker lock fits a standard locker door three-hole door prep, with all electronics contained in a single housing mounted on the front of the locker door and a latch device behind the locker door. The locker lock preferably includes a keypad to allow rotation of a handle or knob, and also includes a manager&#39;s override and power jump terminal.