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CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation patent application which claims priority from U.S. Utility patent application Ser. No. 10/759,413, entitled “PADLOCK,” filed on Jan. 16, 2004, and now issued on Feb. 13, 2007, as U.S. Pat. No. 7,174,756, which in turn claims foreign priority from Taiwanese (ROC) Patent Application No. 092208756, filed May 14, 2003, both of which are herein incorporated by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to a padlock, particularly to a dual-operational padlock which can be operated by either a key or a combination. 
     2. Description of the Related Art 
     A padlock is a well known product and is applicable to a variety of articles which may be under an obvious or potential safety risk, to prevent them from being opened. For example, to prevent an unintended user from opening a luggage, a padlock can be used to lock the overlapped pull tabs of the zipper of the luggage such that the zipper cannot be separated. 
     Generally, based on the locking mechanism utilized, conventional padlocks can be divided into two groups, key-operated padlocks and combination-operated padlocks. These two groups of padlocks have their respective advantages: namely, the key-operated padlock avoids the risk that a combination is forgotten; and the combination-operated padlock does not need a key and thus avoids the risk of losing it. 
     Yang&#39;s U.S. Pat. No. 6,539,761, discloses a padlock combining the functions of a key padlock and a combination padlock. A user thus is able to use either a key or a combination to unlock the padlock. In this case, both locking operations are performed to lock a shackle, and both ends of the shackle are extended into a casing of the padlock and restricted therein. Accordingly, when the padlock is in a locked state, the article hooked by the shackle and restricted by the casing and the shackle cannot be taken off; and when the padlock is in an unlocked state, the shackle axially moves with respect to the casing, and one end of the shackle separates from the casing to form an opening to release the hooked article. 
     According to the disclosure of U.S. Pat. No. 6,539,761 as well as the related prior art, to lock the shackle, the shackle generally has a notch formed thereon for engaging with the locking mechanism associated with the shackle; that is, the notch plays a key role in letting the locking mechanism lock the shackle. The disadvantages resulted therefrom are that the forming of the notch on the shackle needs more machining processes and decreases the structure strength of the shackle. 
     BRIEF SUMMARY OF THE INVENTION 
     A main objective of the present invention is to provide a padlock which can be operated by either a key or a combination. 
     A further objective of the present invention is to provide a padlock which can lock the shackle without the requirement of a notch. 
     To achieve the above objective, the padlock in accordance with the present invention comprises: a casing; a shackle having a free first end and a second end, the second end being pivotally connected to the casing; a locking mechanism received within the casing and limiting the axial movement of the second end of the shackle; a latching tube received and operative to be moved within the casing; and a stop member driven by the latching tube so as to be moved between a first position where the first end of the shackle can be rotated by using the second end thereof as a center of rotation, and a second position where the stop member prevents the first end of the shackle from moving, and the shackle and the casing co-define a closed loop. 
     Other and further features, advantages and benefits of the invention will become apparent in the following description taken in conjunction with the following drawings. It is to be understood that the foregoing general description and following detailed description are exemplary and explanatory but are not to be restrictive of the invention. The accompanying drawings are incorporated in and constitute a part of this application and, together with the description, serve to explain the principles of the invention in general terms. Like numerals refer to like parts throughout the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The objectives, spirits and advantages of the preferred embodiments of the present invention will be readily understood by persons skilled in the art from the accompanying drawings and detailed descriptions, wherein: 
         FIG. 1  is a perspective view of a padlock in accordance with a first preferred embodiment of the present invention; 
         FIG. 2  is a partially exploded view of the padlock in accordance with the first preferred embodiment of the present invention; 
         FIG. 3A  and  FIG. 3B  are schematic views showing the operations of the latching tube shown in  FIG. 1  by inserting a key thereinto; 
         FIG. 4  is a schematic view showing both parts of the casing of the padlock in accordance with the first preferred embodiment of the present invention; 
         FIG. 5  is a perspective view showing a part of the casing of the padlock in accordance with the first preferred embodiment of the present invention; 
         FIG. 6  is a front view of the padlock in accordance with the first preferred embodiment of the present invention; 
         FIG. 7  is a sectional view taken alone Line  7 - 7  in  FIG. 6 ; 
         FIGS. 8A to 8C  are schematic views showing the operations of the padlock in accordance with the first preferred embodiment of the present invention, wherein a key is inserted into the latching tube so as to move the latching tube between a first position and a second position to unlock and lock the first end of the shackle; 
         FIG. 9  is a partially sectional view of the padlock in accordance with the first preferred embodiment of the present invention, wherein an elastic element is optionally provided for biasing the latching tube toward the first position; 
         FIG. 10  is a perspective view of the padlock in accordance with the first preferred embodiment of the present invention, showing the pivotal movement of the first end of the shackle unlocked by using a key; 
         FIGS. 11A and 11B  are schematic views showing the operations of the padlock in accordance with the first preferred embodiment of the present invention, wherein the dials of the combination locking mechanism are adjusted so as to unlock the first end of the shackle; 
         FIG. 12  is a perspective view of the padlock in accordance with the first preferred embodiment of the present invention, showing the pivotal movement of the first end of the shackle unlocked by operating the combination locking mechanism; 
         FIG. 13  is a partially sectional view of a padlock in accordance with a second preferred embodiment of the present invention; 
         FIGS. 14A and 14B  are schematic views showing the operations of a padlock in accordance with a third preferred embodiment of the present invention, wherein a key is inserted into the latching tube so as to move the latching tube between a first position and a second position to unlock and lock the shackle; 
         FIG. 15  is a top plan view of the padlock in accordance with the third preferred embodiment of the present invention; 
         FIGS. 16A and 16B  are perspective views showing the operations of a padlock in accordance with a fourth preferred embodiment of the present invention, wherein a key is inserted into the latching tube so as to move the latching tube between a first position and a second position to unlock and lock the shackle; 
         FIGS. 17A and 17B  are schematic views showing the operations of a padlock in accordance with a fifth preferred embodiment of the present invention, wherein the latching tube is moved between a first position and a second position to unlock and lock the shackle; 
         FIGS. 18A to 18B  are schematic views showing the operations of a padlock in accordance with a sixth preferred embodiment of the present invention, wherein the latching tube is moved between a first position and a second position to unlock and lock the shackle; and 
         FIGS. 19A to 19B  are schematic views showing the operations of a padlock in accordance with a seventh preferred embodiment of the present invention, wherein the latching tube is moved between a first position and a second position to unlock and lock the shackle. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in  FIGS. 1 and 2 , a padlock  1  in accordance with the first preferred embodiment substantially comprises a casing  11 , a shackle  12 , a latching tube  13 , a stop member  14  and a locking mechanism  16 . 
     The shackle  12  is in the shape of a U-shaped bar and has a free first end  121  and a second end  122  which is pivotally connected to the casing  11 . 
     The latching tube  13  is disposed within the casing  11 . In the current embodiment, the latching tube  13  is a disc tumbler cylinder, but can also be a pin tumbler cylinder or other mechanisms performing the similar functions. Further, as shown in  FIGS. 3A and 3B , the latching tube  13  is provided with a plurality of disks  131 , a key hole  132  and a block  133 . The disks  131  are received within the tube body with the peripheral edges thereof retractably extending from the circumferential surface of the tube body. The block  133  is mounted on the circumferential surface of the tube body and is located above the disks  131 . In addition, the key hole  132  is provided on the bottom of the tube body for controlling the movements of the disks  131  in a way that when a key K is inserted into the key hole  132 , the peripheral edges of the disks  131  are retracted to be received within the latching tube  13  (see  FIG. 3A ); and when the key K is withdrawn from the key hole  132 , the peripheral edges of the disks  131  extend out of the circumferential surface of the latching tube  13  (see  FIG. 3B ). Since the latching tube  13  is a conventional member, the detailed structure thereof is not further discussed hereinafter. 
     As shown in  FIGS. 2 ,  4  and  5 , the interior of the casing  11  defines a chamber  111  for receiving the latching tube  13  therein. The inner wall of the casing  11 , which surrounds the chamber  111 , is formed with a substantially L-shaped slot  113  and a recess  112  below the L-shaped slot  113 . In addition, as shown in  FIGS. 6 and 7 , the L-shaped slot  113  includes a transverse slot  114  and a longitudinal slot  115  to receive and restrict the block  133  of the latching tube  13  such that it can only move along the L-shaped slot  113 . The recess  112  is used to receive the peripheral edges of the disks  131  when they extend from the tube body of the latching tube  13 , so as to position the latching tube  13 . In other words, when the peripheral edges of the disks  131  are retracted to be received within the latching tube  13 , the latching tube  13  disengages with the recess  112  of the casing  11  and the block  133  of the latching tube  13  is allowed to move along the transverse slot  114  and the longitudinal slot  115 . 
     The stop member  14  is disposed on the top of the latching tube  13 . In the current embodiment, it is fommed integrally with the latching tube  13  but can also be separate from and be driven by the latching tube  13  in accordance with the other embodiments that will be described later. As shown in  FIGS. 2 ,  3 A and  3 B, the stop member  14  is in the shape of a cylindrical body with the top thereof formed with a hole  141  for receiving the first end  121  of the shackle  12 . 
     The locking mechanism  16  is a conventional combination locking mechanism and is used to limit the axial movement of the second end  122  of the shackle  12  (see  FIG. 2 ). As shown in  FIGS. 11A and 11B , the locking mechanism  16  is received in the casing  11 , at the side opposite to the latching tube  13 , and comprises a plurality of hollow dials  161  with each having an axial groove  162  formed on the inner wall thereof. The second end  122  of the shackle  12  passes through the dials  161  and has a row of axial teeth  123  formed thereon. Each tooth  123  corresponds to an axial groove  162  of the dial  161  such that unless all axial grooves  162  of the dials  161  are rotated to align with the axial teeth  123 , the axial movement of the second end  122  of the shackle  12  will be confined by the dials  161 . Further, to avoid the condition that when all axial grooves  162  of the dials  161  align with the axial teeth  123 , the entire shackle  12  falls out of the casing  11 , a neck portion  117  is formed within the casing  11  such that the second end  122  of the shackle  12  can axially move for a certain distance which should be large enough for releasing the first end  121  of the shackle  12  from the stop member  14 . 
     Based on the above structures, the padlock  1  in accordance with the first preferred embodiment of the present invention is constructed (see  FIGS. 6 and 7 ). 
     The operation of the padlock  1  by means of a key K is described with reference to  FIGS. 6 ,  7 ,  8 A to  8 C, wherein the locking mechanism  16  is adjusted to limit the axial movement of the second end  122  of the shackle  12 . As shown in  FIGS. 6 and 7 , when the padlock  1  is in a locked state, where the latching tube  13  is at a second position and the shackle  12  and the casing  11  co-define a closed loop, the block  133  of the latching tube  13  is located at a first end of the transverse slot  114 , the peripheral edges of the disks  131  engage with the recess  112 , and the first end  121  of the shackle  12  is received within the hole  141  formed on the stop member  14 . 
     By inserting the key K into the key hole  132  of the latching tube  13 , the peripheral edges of the disks  131  are retracted to be received within the latching tube  13  and are disengaged with the recess  112  of the casing  11  (see  FIG. 8A ). Next, the key K is turned clockwise to move the block  133  to a second end of the transverse slot  114 , namely, the intersection between the transverse slot  114  and the longitudinal slot  115  (see  FIG. 8B ). Last, the key K is pulled downward to move the latching tube  13  to the lower end of the longitudinal slot  115 , wherein the latching tube  13  is moved to a first position, the stop member  14 , associated with the latching tube  13 , is separate from the first end  121  of the shackle  12 , and the padlock  1  is in an unlocked state (see  FIG. 8C ). 
     In addition, as shown in  FIG. 9 , to facilitate the downward movement of the latching tube  13  toward the first position, an elastic element, e.g., a spring  15 , is provided within the casing  11 , between the inner upper wall of the casing  11  and the top of the latching tube  13  to bias the latching tube  13  downward. 
       FIG. 10  shows a perspective view of the padlock  1  unlocked by the key K. Since the axial movement of the second end  122  of the shackle  12  is limited, the first end  121  of the shackle  12  can only be rotated by using the second end  122  thereof as a center of rotation and an opening is thus formed between the shackle  12  and the casing  11  so as to hook the desired portions of the article to be locked. 
     To move the padlock  1  back to the locked state, the user first rotates the first end  121  of the shackle  12  to align with the stop member  14 . Further, the key K is pushed upward to move the latching tube  13  upward, until the block  133  of the latching tube  13  presses against the upper end of the longitudinal slot  115 , namely, the intersection between the transverse slot  114  and the longitudinal slot  115 . At this moment, the hole  141  of the stop member  14  engages with the first end  121  of the shackle  12 . The key K is then turned counterclockwise to move the block  133  of the latching tube  13  until it reaches the first end of the transverse slot  114 . Last, the key is withdrawn from the key hole  132  of the latching tube  13  and the peripheral edges of the disks  131  extend out of the circumferential surface of the latching tube  13  to engage with the recess  112  of the casing  11 . Accordingly, the latching tube  13  is moved back to the second position and the padlock  1  is again in a locked state. 
     The operation of the padlock  1  by means of a combination is described with reference to  FIGS. 11A and 11B . As shown in  FIG. 11A , when the padlock  1  is in a locked state, the hole  141  of the stop member  14  engages with the first end  121  of the shackle  12 , the axial movement of the second end  122  of the shackle  12  is limited by the locking mechanism  16 , and the shackle  12  and the casing  11  co-define a closed loop. 
     As shown in  FIG. 4B , by adjusting the dials  161  of the locking mechanism  16  to align the axial teeth  123  formed along the second end  122  of the shackle  12  with the axial grooves  162  of the dials  161 , the second end  122  of the shackle  12  can be moved axially until the first end  121  of the shackle  12  is separate from the stop member  14 . Accordingly, the padlock  1  is in an unlocked state. 
       FIG. 12  shows a perspective view of the padlock  1  unlocked by the combination, wherein the first end  121  of the shackle  12  can be rotated by using the second end  122  thereof as a center of rotation and an opening is thus formed between the shackle  12  and the casing  11  so as to hook the desired portions of the article to be locked. 
     To move the padlock  1  back to the locked state, the user first rotates the first end  121  of the shackle  12  to engage it with the hole  141  of the stop member  14  and the axial teeth  123  of the second end  122  of the shackle  12  simultaneously pass through the axial grooves  162  of the dials  161 . By adjusting the dials  161 , the axial teeth  123  are not allowed to pass through the axial grooves  162  and the padlock  1  is again in a locked state. 
     Based on the above descriptions, the padlock in accordance with the first preferred embodiment of the present invention is disclosed. It can be operated by either a key or a combination. In addition, it can be observed that the stop member  14  and the locking member  16  respectively limits the rotational movement of the first end  121  of the shackle  12  and the axial movement of the second end  122  of the shackle  12  to perform the desired locking function. Further, since there is no notch formed on the shackle  12 , the cost for the additional machining process can be avoided and the structure strength of the shackle is superior to that of the conventional shackle. 
       FIG. 13  shows a partially sectional view of a padlock in accordance with a second embodiment of the present invention. In the current embodiment, a hole  116  is formed within the casing  11 ′. In addition, the locking mechanism  16 ′ comprises a shoulder  124  which protrudes from the second end  122  of the shackle  12  and is pivotally received within the hole  116  of the casing  11 ′ such that the axial movement of the second end  122  of the shackle  12  is limited. However, since there is no combination locking mechanism provided, the padlock in the current embodiment can only function as a key-operated padlock. 
     Nevertheless, by installing the combinational locking mechanism disclosed in the first preferred embodiment into the casing of a currently existing key-operated padlock or the padlock disclosed in the second preferred embodiment disclosed above, it can be modified into a dual-operational padlock. 
     The following descriptions will focus on different arrangements among the first end of the shackle, the stop member and the latching tube of the padlocks in accordance with the different embodiments of the present invention. For the purpose of simplification, an element performing the same function as that does in the first preferred embodiment is denoted by the same reference numeral as that denoted in the first preferred embodiment. 
       FIGS. 14A and 14B  disclose different spatial relationships among a first end  121  of the shackle  12 , a stop member  14  and a latching tube  13  for a padlock  1  in accordance with a third preferred embodiment of the present invention.  FIG. 15  is further directed to the top view of the padlock  1 . 
     As shown in  FIGS. 14A ,  14 B and  15 , in the current embodiment, instead of a hole formed within the stop member  14 , the top of the stop member  14  and the top of the casing  11  are in the same plane, and two opposite stop blocks or arms  142  are protruded upward from the top of the stop member  14  with a space formed between arms  142 . When the padlock  1  is at the unlocked state, the latching tube  13  is at a first position (see  FIG. 14B ) and the first end  121  of the shackle  12  can pass through the space between two arms  142  and can be freely rotated. When the key K is turned 90.degree. clockwise to turn the latching tube  13  to a second position, the stop member  14  rotates together with the rotation of the latching tube  13  such that the arms  142  are located on the path of rotation and secure the first end  121  of the shackle  12  (see  FIGS. 14A and 15 ) therebetween. The padlock  1  is thus in a locked state. 
     In addition, according to the disclosure of the present invention, there is no longitudinal slot required, since the movement of the block  133  along the transverse slot  114  can achieve the desired locking and unlocking operations for the padlock  1 . 
       FIGS. 16A and 16B  disclose different spatial relationships among a first end  121  of the shackle  12 , a stop member  14  and a latching tube  13  for a padlock  1  in accordance with a fourth preferred embodiment of the present invention. 
     The structure and operation of the padlock  1  according to the current embodiment are substantially the same as those of the padlock shown in  FIGS. 14A ,  14 B and  15 , except that the top of the stop member  14  is modified to be a cylindrical body formed with a groove  143  which opens to the periphery of the cylindrical body and defines a bottom aligned with the top of the casing  11 . 
     When the padlock  1  is at the unlocked state, the latching tube  13  is at a first position (see  FIG. 16A ) and the first end  121  of the shackle  12  can be freely rotated into and out of the groove  143 . When the key K is turned 90.degree. clockwise to turn the latching tube  13  to a second position, the stop member  14  rotates together with the rotation of the latching tube  13  such that the groove  143  is oriented 90.degree. to limit the movement of the first end  121  of the shackle  12  (see  FIG. 16B ). The padlock  1  is thus in a locked state. 
       FIGS. 17A and 17B  disclose a spatial relationship among a first end  121  of the shackle  12 , a stop member  14  and a latching tube  13  for a padlock  1  in accordance with a fifth preferred embodiment of the present invention. 
     In the current embodiment, the stop member  14  is indirectly driven by the latching tube  13  by mean of teeth engagement therebetween. As shown in  FIG. 17A , the stop member  14  comprises a gear  173  with a bar  144  laterally attached to the center of the gear  173  at an end thereof. The other end of the bar  144  is provided with a stop plate  145  for holding the first end  121  of the shackle  12  (see  FIG. 17A ), wherein the latching tube  13  is at a second position and the padlock is in a locked state. 
     Moreover, the latching tube  13  is oriented to be movable horizontally. A toothed rack  174  further extends from the top of the latching tube  13  and engages with the teeth of the gear  173 . As the latching tube  13  moves in a direction denoted by Arrow A to a first position, the toothed rack  174  drives the gear  173  to rotate counterclockwise such that the bar  144  is also rotated counterclockwise and the stop plate  145  releases the first end  121  of the shackle  12  (see  FIG. 17B ). In this position, the padlock  1  is in an unlocked state. 
       FIGS. 18A and 18B  disclose a spatial relationship among a first end  121  of the shackle  12 , a stop member  14  and a latching tube  13  for a padlock  1  in accordance with a sixth preferred embodiment of the present invention. 
     In the current embodiment, the stop member  14  is directly driven by the latching tube  13  by means of their respective inclined surfaces. As shown in  FIG. 18A , a corner of the top of the latching tube  13  is formed with an inclined surface  171 . Further, a corner of the bottom of the stop member  14  is formed with an inclined surface  172  corresponding to the inclined surface  171  and the top of the stop member  14  is also formed with a hole  141  for holding the first end  121  of the shackle  12 .  FIG. 18A  shows the latching tube  13  in a second position and the padlock  1  is in a locked state. 
     The latching tube  13  is oriented to be movable horizontally. As the latching tube  13  moves in a direction denoted by Arrow B toward a first position, the stop member  14  moves downward with the inclined surface  172  thereof sliding along the inclined surface  171  of the latching tube  13 . When the latching tube  13  moves to the first position, the stop member  14  releases the first end  121  of the shackle  12  and the padlock  1  is in an unlocked state. 
       FIGS. 19A and 19B  disclose a spatial relationship among a first end  121  of the shackle  12 , a stop member  14  and a latching tube  13  for a padlock  1  in accordance with a seventh preferred embodiment of the present invention. 
     In the current embodiment, the stop member  14  is also directly driven by the latching tube  13  by means of their respective inclined surfaces. As shown in  FIG. 19A , the top of the latching tube  13  is formed with an inclined surface  171 . Further, the bottom of the stop member  14  is formed with an inclined surface  172  corresponding to the inclined surface  171  and the top of the stop member  14  is also formed with a hole  141  for holding the first end  121  of the shackle  12 .  FIG. 19A  shows the latching tube  13  in a first position and the padlock  1  is in an unlocked state. 
     The latching tube  13  is rotatable along a vertical axis of rotation C. As the latching tube  13  rotates 180.degree. to a second position, the inclined surface  171  of the latching tube  13  pushes the inclined surface  172  of the stop member  14  to move upward such that the first end  121  of the shackle  12  is held by the hole of the stop member  14  and the padlock  1  is in a locked state. 
     In conclusion, the present invention provides a padlock having a shackle without a notch, and a padlock is able to position the shackle. Further, the current existing key-operated padlock in the market can be applicable to the present invention to become a dual-operational padlock. 
     Although this invention has been disclosed and illustrated with reference to particular embodiments, the principles involved are susceptible for use in numerous other embodiments that will be apparent to persons skilled in the art. This invention is, therefore, to be limited only as indicated by the scope of the appended claims.

Summary:
A multiple function lock, which has dual, independently operated, locking mechanisms. In one embodiment, the multiple function lock is further comprised of a combination locking mechanism and a keyed locking mechanism. In one embodiment, the multiple function lock is further comprised of a gate mechanism for selectively securing and releasing a shackle of the lock.