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You are an expert at summarizing long articles. Proceed to summarize the following text: 
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. application Ser. No. 13/698,458, filed Nov. 12, 2012, which claims the benefit of International Application No. PCT/SG2010/000194, filed May 25, 2010, each of which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Typical conventional locking devices, such as padlocks and luggage locks, require user to manually enter a sequence of numbers by adjusting multi-rotating dials inscribed with numeric digits to open a lock. This type of locking devices is commonly known as Combination Locks and they usually do not require a mechanical key. Instead users need to preset a combination digit code and remember this code when unlocking such locks. In contrast, existing electronic locks are usually designed with a bulky and relatively large numeric keypad for entering access codes. These keypads are not suitable for used in small size electronic combination locks. 
     The invention is concerned with small size electronic combination locks. In particular, the invention relates to miniaturization and an easy-to-use electronic identification method for setting locking and unlocking combination access code of electronic combination locks such as padlocks, chain locks, luggage locks, wire locks and bicycle locks. 
     The method of adjusting mechanical combination codes to unlock conventional locking devices is cumbersome and time consuming. The problems of using such combination locks are as follows: (1) reading and adjusting small size of inscribed digits on the rotating dials become tedious and time consuming (2) limited numeric digits from 0 to 9 resulted little choices of access code that can be formed by user (3) memorizing multiple numeric digits of access codes can be difficult to some users. 
     In addition to above shortcomings of conventional combination locks, there has been a need for a small electronic lock operated by an electronic identification device with characteristics as follows: easy to use due to its simplicity, increased variety of choices of combination codes, very low battery power consumption, and relatively inexpensive construction. 
     U.S. Pat. No. 4,495,540, describes an electronic combination lock for luggage. The electronic combination lock described in this patent comprises several buttons which emulate the mechanical adjustable rings in conventional combination locks. It is a replicate of multi-digit mechanical adjustable rings to several electronic push buttons. These multiple buttons method of entering access code is not suitable for application in small electronic combination locks. The patent is incorporated here for reference. 
     The followings additional patents are believed to have relevance to the invention: U.S. Pat. No. 3,754,164, U.S. Pat. No. 4,931,789, U.S. Pat. No. 5,021,776, U.S. Pat. No. 5,153,561, U.S. Pat. No. 5,373,718, 
     To address the weaknesses and the needs described above, the inventor proposed an alternative electronic combination lock which provides the public with a useful choice. 
     SUMMARY OF INVENTION 
     The invention provides an electronic combination lock comprising an electronic system unit, a mechanical housing, a miniaturized latch and a set of switches or sensor to manually and automatically turn on/off the electronic system. The electronic system consist of a visual display unit, a small Joystick switch or a set of switches or a touch sensor or a plurality of optical sensor, to provide a means of entering and setting access code, a microcontroller programmed with software in combination with electronic circuitry to drive a miniaturized toggle solenoid or a micro motor to perform locking and unlocking functions. The compact electronic system unit fit to the mechanical housing to form a unitary embodiment of electronic locking device. 
     Using a set of mechanical switches or a sensor and software protocol, an automatic device “waking-up” method is derived to prevent unnecessary turning on its electronic system when not in used to conserve battery power. The electronic system is normally programmed to automatically power off and can be manually turned off using a press button. The electronic system can be activated by the following actions: 1). manually press an on/off button, 2). automatically triggered by a displacement sensor (e.g. acceleration sensor, vibration sensor, movement sensor) when an appropriate movement or combination of movements of the lock detected. The movement or combination of movements may be a preset pattern or combination of movements such as a press on the shackle bar followed by an immediate release against the body of the lock. This pattern or combination of movements may be predefined in the electronic system for the purpose of activating the electronic system or executing some other function. 
     The combination of electronic display, a 5-way switch Joystick or a touch sensor and the software in conjunction with an electronic controller, enable a vast variety and choices of access codes are constructed by an user. Access codes can be stored in memory of the electronic system. Alphanumeric characters, colors graphics, shapes, symbols, patterns and other language characters, and their combinations to form words, names, and others combination to produce a vast variety of high security access codes that are meaningful, user-friendly, and easy for user to remember. More than one access code can be set to enable several users to use one electronic combination lock with different access code set for the convenient of each particular user. 
     When using a touch sensor for access code entry, user can touch and scroll to search for the alphanumeric characters or patterns displayed on screen and click the choice for performing access code entry actions. The display unit (e.g. LCD display) can be illuminated to ease reading of access code in a less illuminated environment. 
     A separate battery operated electronic key unit, which contents a programmed access code and electronic circuitry, can be used in conjunction with the electronic combination lock. The electronic key can serve as: (1) a proximity controller to perform locking and unlocking actions (2) an alternative power source to boot up the electronic combination lock with a flatten battery. (3) Backup access code storage. 
     The invention thus provides a miniature, compact, easy for entering/setting vast choices of access code, user-friendly locking and unlocking features, low power consumption, easy to use electronic combination lock and can advantageously replace the use of conventional combination locks. 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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The details of the electronic combination lock and electronic key will be understood more clearly with reference made to the accompanying drawings, in which: 
         FIG. 1  is a front elevational view of one embodiment of the digital combination lock of the present invention; 
         FIG. 2  is a bottom elevational view of the present invention showing a battery compartment and a key way; 
         FIG. 3  is a back elevational view of the interior of the digital combination lock in closed position showing a solenoid locking into the shackle bar; 
         FIG. 4  is a back elevational view of the interior of the digital combination lock in opened position showing a solenoid releasing from the shackle bar; 
         FIG. 5  is a front perspective view of the overall view showing a touch screen as the controller for the input of access codes into the invention; 
         FIG. 6  is a front perspective view of the overall view showing a joystick as the controller for input of access code into invention; 
         FIG. 7  is the front perspective view of the overall view showing the electronic combination lock embedded on a luggage bag. 
         FIG. 8  is a top elevational of the electronic key showing a button extended the contact point out of the casing; 
         FIG. 9  is a top elevational of the electronic key showing the contact retracted into the casing; 
         FIG. 10  is a front elevational of the electronic key showing the contact and infra red; 
         FIG. 11  is a top elevational of the electronic key showing the interior of the lock with all the components 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     An embodiment of an electronic combination padlock can best be appreciated by referring to  FIGS. 1 and 2 . The electronic combination lock having a mixture of metal and plastic material to form a housing structure  1 , preferably elongated, consists of metal plates  2  on the top and bottom of the housing  1  to reinforce the structure. The lock has a shackle-type locking bar  3  that is held lock in position within the housing  1 . The front side of the housing  1  has a back-lighted touch screen Liquid Crystal Display (LCD)  4  either by color pixels or dot matrix which is capable of displaying combination of alphanumeric characters, symbols and patterns. It will be appreciated that LCD screen  4  includes both a touch sensor and an electronic display unit. The touch feature on the LCD screen  4  allows entering and controlling locking features. The LCD screen  4  is automatically turned off within a short duration to conserve battery power. In this preferred form described herein, the electronic combination lock uses six “digital dials” access code (a smaller or larger number of dials can also be used). An On/Off push button  5  is situated below the LCD screen  4  to turn on or off the lock electronic system. Alternative method of turning On the device is achieved by shaking the lock which will trigger the movement sensor  16  and thus activating the electronic system of the electronic combination lock  17 . The electronic system may be automatically activated, for example, by the movement sensor  16  (e.g. acceleration sensor, vibration sensor, displacement sensor), when an appropriate movement or combination of movements of the lock is detected. The movement or combination of movements may be a preset pattern or combination of movements such as a press on the shackle bar followed by an immediate release against the body of the lock. This pattern or combination of movements may be predefined in the electronic system for the purpose of activating the electronic system or executing some other function. As seen in  FIG. 5 , a receiver  6  for an infrared or radio frequency receiver system is situated to the right of the LCD screen  4  to receive signal from the electronic key  43  for performing locking and unlocking functions. The electronic key  43  may be in the form of a smartphone, tag, fob or some other smart device or the like that includes the necessary software and hardware to transmit infrared or radio frequency signals to the receiver  6  of the electronic system. 
     In embodiments, activating the electronic system of the electronic combination lock may also be achieved through a shaking of the electronic key  43  in an appropriate movement, pattern or combination of movements, which may be detected by a movement sensor within the electronic key  43 , such as an acceleration sensor, vibration sensor, displacement sensor or the like. As with the shaking of the lock itself, the movement or combination of movements may be a preset pattern or combination of movements that are predefined for the purpose of activating the electronic system or executing some other function. The pattern of shacking of the electronic key  43  may generate a dedicated external proximity wireless signal to energize an antenna sensor through the receiver  6  of the electronic combination lock thus activating part or the entirety of the electronic system of the lock. 
     The bottom of the housing  9  is the battery compartment, which is enclosed by the battery cap  7 . It permits two batteries  10  to be contained in the compartment. To the right of the battery cap  7  is the key hole  8  for the electronic key to be inserted in to unlock the electronic combination lock as an alternative method. When the electronic combination lock battery  10  has drained off completely, the battery source  22  from the electronic key can be used to power up the electronic combination lock. In an example embodiment, both the status of the electronic combination lock and a preprogrammed access code remain in an initial state as stored in a memory for the electronic system regardless of whether battery  10  is being removed or is completely discharged. 
     Referring to  FIGS. 3 and 4 , the inner section of the housing  1  is preferably made from metal and the components are secured to the housing. The shackled bar  3  is held within the inner section by a solenoid  11  actuated bar  12  or a miniature motor. The shackled bar  3  is spring loaded  21  at one end. The shackle bar  3  is held by an actuated bar  12  secured into the groove  13  of the shackle bar  3 . When an access code is entered by user to perform locking action, a signal is sent to the microcontroller  23  held on the circuit board, it drives the solenoid  11 . The solenoid  11  will in turn actuate the actuated bar  12  to move forward. Upon actuation, actuated bar  12  will move into the groove  13  of the shackle bar  3  thereafter a second spring loaded bar  14  will move into the hole  15  of the actuated bar  12 . The spring bar  14  acted as safety barrier to prevent the actuated bar  12  from unintentionally release from the latched position. A spring load ball bearing  18  is used to assist holding the shackle bar  3  in position for the actuated bar  12  to insert in and move out to accommodate latching and unlatching actions. 
     When an access code is entered on the electronic combination lock or a pre-programmed electronic key with access code is inserted into connector  8 , a signal is sent to the microcontroller  23  to release the shackle bar to trigger the toggle solenoid  19  which in turn retracts the bar  14 . Upon retraction, solenoid  11  will actuate to move the actuated bar  12  backward. Shackle bar  3  will spring out of the holding position into unlock position. After a certain duration solenoid  19  will release bar  14  into latching hole  20  to keep the actuated bar  12  from moving during unlocking state. 
     The electronic combination lock may also include a battery compartment lock  42  that secures the battery  10  in its battery compartment within the lock housing  1 , shown in  FIG. 1 , by engaging and disengaging the battery cap  7  when the shackle bar  3  is in the locked position and unlocked position, respectively so that the battery  10  is inaccessible when the electronic combination lock is in the locked position. 
     Referring to  FIG. 6 , it shows another preferred embodiment using the joystick mechanism  34  as the input device. Access code  33  displayed on LCD screen can be in the forms of alphanumeric characters, symbols and patterns. On the right of the joystick mechanism is the mode button  32  to select a particular feature required. On the left is the On/Off button  31  to power On or Off the electronic system within the electronic combination lock. 
       FIG. 7  illustrates another preferred embodiment of the electronic combination lock embedded in a luggage bag  40 . The pull tabs  41  of the luggage are to be inserted into the metal hooks  37  of the mechanical housing  38 . In this embodiment, the shackle bar  3 , shown in  FIG. 1 , may be in the form of one or more luggage zipper hooks or cylinder lock latches within the mechanical housing  38  that may be actuated to engage and disengage the pull tabs  41  to lock and unlock, respectively, the luggage bag  40  in substantially the same manner discussed above. Numerical  35  is the mode button to select a specific feature of the electronic luggage lock. On the right side of the mode button  35  is the On/Off button  36  to power on or off the electronic system. A LCD screen  39  is available for displaying access code and other features such as displaying lock status, wrong access code, selected type of code etc. 
     Referring to  FIGS. 8 to 10 , the electronic key module comprises a plastic housing  24 , unlock push buttons  25 , lock push button a retractable connector  27  and infra red transmitter  28 . The electronic key has two ways to open the electronic combination lock. Referring to  FIG. 7 , connector  27  is pushed out and inserted into the key hole  8  of the housing. The pre-programmed unlocking access code for the electronic lock is stored in memory of the integrated circuit  29 . Upon insertion into the key hole  8 , it sends a signal to the microcontroller  23  once the access code validated, the unlocking sequences is activated. This method of unlocking the electronic combination lock can be performed regardless the presence of battery source  10 . For instance, the preprogrammed access code may be read by the electronic system of the lock to provide power to a dedicated electronic sub-system for triggering by-pass unlocking function of the said lock when the connector  27  is inserted in the key hole  8  in the housing. Alternative method of unlocking the electronic combination lock is to use the infra red transmitter  30 . Within a proximity range of the circuit, with a press on the unlock button  26 , a signal from the transmitter  30  sends to the receiver of the electronic combination lock  6  which then triggers the microcontroller to perform locking and unlocking sequences.

Summary:
Disclosed herein is an electronic combination lock mainly characterized by miniature size and easy-to-use electronic identification access-gaining method that enables a vast variety and type of access codes for user setting and choice. Another battery operated electronic key unit, incorporated with programmed access code to provide as an alternative choice for locking, unlocking and backup power, can be used in conjunction with the electronic combination lock.