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 
     The present invention relates to a lock used for the cabinets in public places, more particularly a lock, which takes the form of a combination lock, and of which the combination of numbers can be reset by the present user. 
     Storage cabinets are provided for customers to keep their personal objects in public places such as railway stations, swimming pools, shopping centers, and spas. The storage cabinets are usually equipped with a lock such that they can prevent the personal objects of the customers from being stolen when the customers keep the objects in them. The customers can lock those objects in the cabinets that are not needed while they are getting service in the public places, and only have to carry a key for the lock of the cabinets with them. Therefore, the storage cabinets are very convenient to use. 
     However, such cabinets are found to have a disadvantage because of the type of the locks that they are provided with; the customers might lose the key for the lock while they are getting service in the public places, causing themselves a lot of trouble; and, a thief can pretend to store his personal objects in the cabinets in order to get the key for the lock, and have the key reproduced such that he can open the lock with the reproduced key to steal other people&#39;s objects some other time. 
     SUMMARY OF THE INVENTION 
     Therefore, it is a main object of the present invention to provide a lock for a cabinet in public places, which takes the form of a combination lock, and of which the combination of numbers for opening it can be reset by the present user. 
     It is an other object of the present invention to provide the combination lock such that the cabinet can be opened by a spare key kept in the counter should the user forget the combination of numbers that he set, and that the forgotten combination of numbers can be found out by a probing needle. 
     The combination lock of the present invention includes a housing member, several control rings each separably engaged with a wheel, a lock rod, a control block and an operating rod. 
     The wheels are turnably disposed in the housing members, and are each marked with spaced numerals on the outer side. The control rings each has spaced projections on the outer side to engage spaced teeth on the inner side of the wheel. The control rings each has a through hole formed with both a central round portion and a square portion. 
     The lock rod is passed through the control rings from a rod part that has spaced projections, each of which sticks rearwards and has gap. A spring is disposed under a lowermost one of the control rings to bias same up. 
     The control block has a centrol hole formed lengthwise therein and several concavely curved portions lengthwise formed on the outer side that include a first one and a second one shallower than the first one. The control block is lengthwise passed through an upper portion of the housing member to abut a curved propping block placed on an uppermost one of the control rings. 
     The operating rod is passed through the control hole of the control block from a middle rod portion, and has a front knob sticking out from the front side of the housing, and is connected to locking plate at the rear end. The middle rod portion engages the control block, and can be disengaged from same when a spare key is inserted into the keyhole of the operating rod. 
     Thus, the control rings can be pressed down and disengaged from the wheels when the control block is turned together with the operating rod to abut the propping block at the shallow second curved portion thereof allowing the wheels to be turned relative to the control rings for resetting the unlocking combination of numbers. When the control rings are biased by the spring to engage the wheels, and the wheels are turned randomly with the control block abutting the propping block at the first deep curved portion, the lock is locked and the locking plate keeps the cabinet door closed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view of the combination lock of the present invention. 
     FIG. 2 is a perspective view of the housing member and the panel of the combination lock of the present invention. 
     FIG. 3 is a perspective view of the lock rod of the combination lock of the present invention. 
     FIG. 4 is a front view of the combination lock of the present invention in the unlocked position. 
     FIG. 5 is a side view of the combination lock of the present invention in the unlocked position. 
     FIG. 6 is a bottom view of the combination lock of the present invention in the unlocked position. 
     FIG. 7 is a view showing the orientation of the control rings in relation to the lock rod in the unlocked position according to the present invention. 
     FIG. 8 is a front view of the combination lock of the present invention in the locked position. 
     FIG. 9 is a side view of the combination lock of the present invention in the locked position. 
     FIG. 10 is a view showing the orientation of the control rings in relation to the lock rod in the locked position according to the present invention. 
     FIG. 11 is a view of the combination lock being opened by the spare key. 
     FIG. 12 another view of the combination lock being opened by the spare key. 
     FIG. 13 is a view showing a probing needle being passed up through the passage for finding out the opening of the combination of numbers for the lock. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIGS. 1 and 2, a lock used for the depository cabinet in public places of the present invention includes a housing member  1 , a panel  2 , a lock rod  3 , a spring  4 , several wheels  5 , control rings  6 , a propping block  7 , a control block  8 , an operating rod  9  and a back board  10 . 
     The housing member  1  has connecting holes  11  at the corners, a round holding room  12  at the upper portion, a gap  13  formed at the bottom of the holding room  12 , an inner wall  19 , an outer wall  18 , several separating boards  15  spaced out from under the holding room  12  to the lower end thereof a bottom hole  17  at the bottom, and elastic tenons  181  provided on the outer walls  18 ; a through passage hole  121  is formed on the center of the rear wall of the holding room  12 ; a restricting trench  122  is formed on the upper side of the holding room  12 ; the separating boards  15  are shaped to have gaps (not numbered) such that the lock rod  3  can be passed therethrough, and the control rings  6  can be received in the gaps when moved down in operation of the lock; a space  100  (FIG. 2) is provided between the inner and the outer walls  19  and  18 ; two engaging trenches  172  are formed at the lower end portion of the housing member to oppose each other beside the bottom hole  17 ; a curved trench  171  is formed on the lower end portion of housing member  1  behind the bottom hole  17 ; a lateral connecting hole  182  is formed on the outer wall  18 . The housing member  1  further has flexible legs  14 , each of which sticks out from the lateral sides into between two adjacent ones of the separating boards  15 , and each of which has a convexly curved blocks  141  at the inward end. Many elongated holes  16  are formed on the rear side of the housing member  1  due to the separating board  15  as shown in FIG.  2 . 
     The back board  10  is folded to have a recess  101  at the upper portion, and has a locating pole  103 , an insertion protrusion  104 , and a connecting hook  102 , which all stick out from the lower portion thereof. The back board  10  is fitted to the housing member  1  with the locating pole  103  being passed into the uppermost one of the elongated holes  16 , the insertion protrusion  104  being passed through the lowermost one of the elongated holes  16  to engage the lowermost one of the separating board  15 , and with the connecting hook  102  being passed into the space  100  to engage the lateral connecting hole  182  of the outer wall  18 . 
     The housing member  1  is secured to the door of a depository cabinet by means of fitting the elastic tenons  181  thereof into mortises provided on the depository cabinet door. 
     The panel  2  has connecting poles  21  on the rear side, a round hole  23  on the upper portion, an inspection hole  24  above the round hole  23 , and several slots  25  spaced out from below the round hole  23  to the lower end portion thereof; the connecting poles  21  each as a screw hole on the rear end. The panel  2  is, after the wheels  5  have been disposed in the housing member  1 , secured to the front side of the housing member  1  with the connecting poles  21  being passed into a respective one of the connecting holes  11  of the housing member, and with the round hole  23  opposing the holding room  12  and the slots  25  facing a corresponding one of the spaces between the separating boards  15 ; screws  22  are screwed into the screw holes of the connecting poles  21  from the rear side of the housing member  1  to prevent the panel  2  from falling off. 
     The lock rod  3  has an insertion plate  31  on the bottom, a root part  34  on the insertion plate  31 , and a rod part  32  sticking up from the root part  34 . Referring to FIG. 3, the lock rod  3  is formed with several projections  33  spaced out on the rear side of the rod part  32 , each of which has a gap  331  extending from the top to the bottom. A gap  341  is formed on the rear side of the root part  34  and the insertion plate  31  to be aligned with the gaps  331  such that an upright passage is formed on the rear side of the lock rod  3 . The rod part  32  of the lock rod  3  is passed through the gaps of the separating boards  15  with the projections  33  being opposite the rear side of the housing member  1 , and the insertion plate  31  is inserted into the engaging trenches  172  from two ends. 
     The spring  4  is passed around the lock rod  3  to be disposed at the lower portion of the same. 
     The wheels  5  each has engaging teeth  53  spaced out on the inner side, and is marked with spaced out numerals ( 0  to  9 )  51  on the outer side; curved recesses  52  are formed on both the upper and the lower portions of the spaces between the numerals  51 . 
     The control rings  6  are each separably fitted into a respective one of the wheels  6 , and each has a through hole  61  and engaging projections  62  spaced out on the outer side; the through hole  61  includes a round portion on the center of the ring  6  and a square portion next to the round portion; the engaging projections  62  engage the teeth  53  of the corresponding wheel  5  such that each of the control rings  6  can be turned together with the corresponding wheel  5  when it is fitted into the same. 
     The wheels  5  are disposed in the gaps of the separating boards  15 , and kept separate from each other by the separating boards  15  such that the front portions of the wheels  5  stick out through the slots  25  of the panel  2  for allowing a user to turn the wheels in operation of the lock. The rod part  32  is passed through the wheels  5  and the through holes  61  of the control rings  6  such that the control rings  6  are biased up by the spring  4  to be received in the respective wheels  5 ; when the control rings  6  are pressed downwards to become separate from the wheels, the engaging projections  62  no longer engage the teeth  53  of the wheels  5 , following the orientation of the square portions of the through holes  61  of the same in relation to the wheels  5  to be changed by turning the wheels  5  about the lock rod  3  relative to the same. 
     The propping block  7  has a propping top  71  having a convexly curved surface, and an engaging hole  72  on the lower side that also has a round portion and a square portion next to the round portion. The propping block  7  is disposed on the uppermost one of the control rings  6 , and fitted around the top end of the lock rod  3  from the engaging hole  72 ; thus, the uppermost rearward projection  33  of the lock rod  3  is received in the square portion of the hole  72 . 
     The control block  8  is substantially shaped like a hollow cylinder that has a central hole  84 , and several concavely curved portions lengthwise formed on the outer side thereof, the concavely curved portions include a first one  81  and a second one  82  that is shallower than the first one  81 . The angle defined by both the normal to the bottom of the first concavely curved portion  81  and the normal to the bottom of the second one  82  is  90 . The control block  8  further has a pair of opposing trenches  85  on the inner side, one of which is on the opposite side of the second concavely curved portion  82 , and has a restricted projection  83  on the outer side. The control block  8  is turnably passed into the holding room  12  of the housing member  1  with the outer side coming into contact with the propping top  71  of the propping block  7 ; when the first concavely curved portion  81  faces the propping top  71 , the propping block  7  is not moved down by the control block  8 , and the control rings  6  are engaged with the wheels  5 ; when the second concavely curved portion  82  that is shallower than the first one  81  faces the propping top  71 , the propping block  7  is moved down, making the control rings separate from the wheels  5 . In addition, the restricted projection  83  will be confined in the restricting trench  122  of the holding room  12  of the housing member such that the turning movement of the control block  8  is limited. 
     The operating rod  9  includes a knob portion  91  at the front end, a rod-shaped portion  92  at the middle, and a connecting portion  93  at the rear end. The middle portion  92  has a slot (not numbered), which has several insertion trenches  921  on one lateral side and round trenches  922  opposing the insertion trenches on the other side as shown in FIGS. 1,  4  and  9 ; the insertion trenches  921  are formed in such a manner as to communicate with each other, while the round trenches  922  don&#39;t communicate with each other. The knob portion  91  has a keyhole  98  communicating with the slot of the middle rod-shaped portion  92 . Referring to FIG. 4, the insertion trenches  921  and the opposing round trenches  922  have insertion plates  97  fitted thereonto; the insertion plates  97  each has an elongated hole  971 , a stopping portion  972  received in the corresponding round trench  922 , and a tooth  973  received in the corresponding insertion trench  921 ; springs  96  are disposed in the round trenches  922  to contact the stopping portion  972  so as to bias the insertion plates  97  outwardly of the slot of the middle portion  92 ; the teeth  973  will be blocked by the ends of the insertion trenches  921  when the springs  96  bias the plates  97  outwards such that the plates  97  can&#39;t fall off. The connecting portion  93  is shaped like a cylinder with two opposite straight sides, and has threads  931  on the curved sides. 
     The operating rod  9  is passed through the round hole  23  of the panel  2 , and the central hole  84  of the control block  8  from the middle portion  92  thereof such that the insertion plates  97  will be biased by the springs  96  to engage the inner trenches  85  of the block  8  when the ends thereof oppose the inner trenches  85 . The rear connecting portion  93  sticks out from the control block  8 , and is passed through a rectangular hole of a locking plate  94 , which is disposed in the recess  101  of the back board  10 ; a nut is screwed onto the connecting portion  93  to prevent the locking plate  94  from moving relative to the same. 
     When a user wants to use a depository cabinet with the lock of the present invention, he should find out whether the cabinet is in use or not by means of looking through the inspecting hole  24  of the front panel  2  to find the position of the locking plate  94 ; if the cabinet is not in use, the locking plate  94  will be upright, i.e. it can be seen by the user. Referring to FIGS. 4 to  7 , when the combination lock is opened, i.e. the square portions of all of the control rings  6  are aligned with the projections  33  of the lock rod  3 , the user can turn the operating rod  9  such that the second concavely curved portion  82  of the control block  8  is mounted on the propping block  7  to press the block  7  downwards; thus, the control rings  6  are separate from the wheels  5 , allowing the orientation of the control rings  6  in relation to the wheels  5  to be changed when the wheels  5  are turned by the user. Thus, the combination of numbers capable of opening the lock can be reset by the present user. The user then turns the operating rod  9  such that the locking plate  94  is moved to a laid down position and the first concavely curved portion  81  is mounted on the propping block  7 ; because of the depth of the first portion  81 , the control rings  6  plus the propping block  7  are biased up by the spring  4 , and the control rings  6  engage the wheels  5  again from the spaced engaging projections  62 . The lock plate  94  prevents the cabinet door from being opened that is in the laid down position, and the projections  33  of the lock rod  3  stop the control rings  6  from being moved down after the wheels  5  have been turned away from the combination of numbers capable of opening the lock. Therefore, the propping block  7  is fixed in position to engage the first concavely curved portion  81 , preventing the control block  8  from being turned; in other words, the locking plate  94  can&#39;t be turned back to the upright unlocked position. 
     When the present user wants to open the lock to withdraw the things deposited in the cabinet, he only has to turn the wheels  5  to the unlocking position according to the combination of numbers that he set, and turn the operating rod  9  to make the locking plate  94  move to the upright position such that the cabinet door becomes openable. 
     If the user forgets the unlocking combination of numbers, the user has to have the lock opened by a spare key  30  kept in the counter, when the spare key is inserted into the keyhole  98  and the elongated holes  971  of the insertion plates  97  received in the middle portion  92 , the insertion plates  97  will be moved so as to disengage the inner trenches  85  of the control block  8 , allowing the operating rod  9  and the locking plate  94  to be turned with the control block  8  being still fixed in position for opening the cabinet door. 
     After the cabinet door is opened, the counter staff has to pass a probing needle  20  into the upright passage  331  in order to find out the forgotten opening combination of numbers that is set by the last user, if the upper end of the probing needle  20  is blocked by the control rings  6 , he has to turns the wheels  5  connected to the control rings  6  to such a position that the probing needle  20  can be moved through the passage  331 . Thus, the combination lock is opened again so that the next user can make the control block  8  turn to press the control rings  6  down for resetting his opening combination of numbers by means of the wheels  5 . 
     Furthermore, the convexly curved blocks  141  provided at the ends of the flexible legs  14  can be fitted onto the curved recesses  52  of the wheels  5  such that the user can exactly turn the wheels  5  to the positions where the lock can be opened. 
     From the above description, it can be easily understood that the lock of the present invention has advantages as followings: 
     1. Every user can set a combination of numbers that only he knows so that his belongings can be safely deposited in the cabinet. There is no risk of losing a key or possibility of early users opening the lock with old unlocking combination of numbers. 
     2. Should the present user forget the combination of numbers that he set, the cabinet door still can be opened with the spare key in the counter. 
     3. After the cabinet door is opened with the spare key, the forgotten combination of numbers can be found out with the probing needle such that the lock still can be used with reset combination of numbers by other users.

Summary:
The present invention relates to a lock used for the cabinets in public places, in which the number of lock can be reset when used to secure the items of users.