Patent Publication Number: US-2023147055-A1

Title: Method for identifying coin

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2021-0153331, filed on Nov. 9, 2021, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Field of the Invention 
     The present disclosure relates to a method for identifying a coin, and more particularly, to a coin identifying method capable of simultaneously identifying a type of coin and whether the coin is defective. 
     2. Discussion of Related Art 
     Generally, as means for payment for public transport, contactless cards, coupon ticket, bills, coins, or the like are used. In a case in which coins are used among the above means for payment, since various types of coins are input, there is great difficulty in counting the coins. 
     In particular, in a case in which a transportation fee is paid with coins, there are problems that it is not easy to check whether the paid transportation fee is a correct fee, and when a driver checks whether the paid transportation fee is a correct fee, the driver cannot concentrate on driving, and the risk of accidents increases. 
     Korean Unexamined Patent Application Publication No. 10-2008-0102511 discloses a coin sorting device. The coin sorting device includes a sorting housing in which a circular accommodating portion is formed and coin holes corresponding to different sizes of coins are each perforated in a bottom surface thereof along an inner sidewall of the accommodating portion and a separating rotary plate which is rotatably mounted on the accommodating portion to transfer coins input to the accommodating portion along the inner sidewall of the accommodating portion and separate and discharge the coins through the coin holes according to different types of coins. 
     Also, Korean Unexamined Patent Application Publication No. 10-2007-0106208 discloses a coin counting device. The disclosed coin counting device includes a rotary plate configured to withdraw coins by a centrifugal force, a high-speed transfer roller configured to withdraw the withdrawn coins again by a rotary force thereof to transfer the withdrawn coins at a high speed, and a transfer path configured to guide the withdrawn coins toward a counting detector, wherein the transfer path has a curved portion provided on a distal end thereof, and an impact absorbing member is disposed on the curved portion to, when the withdrawn coins reach the curved portion from the high-speed transfer roller, reduce an impact thereof and transfer the coins along one sidewall. 
     Korean Patent Registration No. 10-0663636 discloses a coin counting device, and Korean Patent Registration No. 10-0910963 discloses a coin counting device using a camera and a method of controlling the same. 
     In the conventional coin counting devices configured as described above, according to different materials of coins, some coins passing through a coin transfer path tend to not be detected in a coin sorting process, and thus reliability of detecting and counting coins cannot be improved. Also, counting input coins and dispensing change are difficult. 
     Japanese Patent Publication No. 13060277 discloses a coin counting sorting device, and Korean Unexamined Patent Application Publication No. 10-2008-0102520 discloses a recovering device of a teller machine for a coin counter. 
     The conventional coin counting devices mentioned above have problems that it is not possible to suppress an occurrence of jamming during sorting and counting of coins and it is not possible to discharge defective coins. In a case in which defective coins are not able to be discharged, there is a problem that change cannot be smoothly dispensed. 
     RELATED ART DOCUMENTS 
     Patent Documents 
     Korean Unexamined Patent Application Publication No. 10-2008-0102511: coin sorting device of teller machine for coin counter 
     Korean Patent Registration No. 10-0663636: coin counting device 
     Korean Patent Registration No. 10-0910963: coin counting device using camera and method of controlling the same 
     SUMMARY OF THE INVENTION 
     The present disclosure is directed to providing a coin identifying method capable of simultaneously identifying a type of input coin and whether the input coin is defective. 
     A coin identifying method of the present disclosure includes: a reference data obtaining operation in which different types of normal coins are input to a coin counting device, in which a coin guider forming a coin movement path is provided, to store each of a maximum or minimum frequency value output while the normal coins pass a first inductor of a coin identifier installed on the coin guider, a maximum or minimum frequency value output while the normal coins pass a second inductor, and width values of linear graphs of changes in frequencies from a point in time at which a frequency changes while the normal coins pass the second inductor until the frequency returns to a reference frequency and obtain identification reference value data for each type of the normal coins; and a coin type and defect identifying operation in which a maximum or minimum frequency value output while a coin to be identified, which is input to the coin counting device, passes the first inductor, a maximum or minimum frequency value output while the coin to be identified passes the second inductor, and a width value of a linear graph of changes in frequencies from a point in time at which a frequency changes while the coin to be identified passes the second inductor until the frequency returns to a reference frequency are compared with the identification reference value data to simultaneously determine a type of the coin to be identified and whether the coin to be identified is defective. 
     The first inductor may be mounted on the coin guider so that, according to a diameter of the normal coin or the coin to be identified moving while in contact with one side portion of the coin guider, an area covered by the normal coin or the coin to be identified changes, and the second inductor may be spaced apart from the first inductor in a direction in which the coin guider extends and may be installed on the coin guider to be more adjacent to the one side portion of the coin guider than the first inductor so that the second inductor is always entirely covered by the normal coin or the coin to be identified. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present disclosure will become more apparent to those of ordinary skill in the art by describing exemplary embodiments thereof in detail with reference to the accompanying drawings, in which: 
         FIG.  1    is a perspective view of a coin counting device to which a coin identifying method according to one embodiment of the present disclosure is applied; 
         FIG.  2    is a perspective view of a portion of the coin counting device of  FIG.  1   ; 
         FIG.  3    is a partially cut-out plan view of the coin counting device of  FIG.  1   ; 
         FIG.  4    is an exploded perspective view of the coin counting device of  FIG.  1   ; 
         FIG.  5    is a block diagram of a coin identifying method according to an embodiment of the present disclosure; 
         FIG.  6    is a view illustrating a state in which a coin passes a first inductor; 
         FIG.  7    is a view illustrating a state in which a coin passes a second inductor; 
         FIG.  8    is a view relating to changes in frequencies when a coin made of a nonferrous material passes the first inductor; 
         FIG.  9    is a view relating to changes in frequencies when a coin made of a nonferrous material passes the second inductor; and 
         FIG.  10    is a block diagram of a coin identifying method according to another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Hereinafter, a coin identifying method according to an exemplary embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. 
     Prior to describing the coin identifying method according to an embodiment of the present disclosure, a coin counting device  10  to which the coin identifying method according to an embodiment of the present disclosure is applied will be briefly described with reference to  FIGS.  1  to  4   . 
     The coin counting device  10  having a defective coin sorter according to the present disclosure includes: a coin separation unit  20 ; a defective coin discharge unit  30 ; a coin supply unit  50 ; a coin transfer unit  70 ; a coin loading and change discharge unit  100 ; and a controller (not illustrated). 
     The coin separation unit  20  is installed on an upper portion of a support frame  11  and includes a coin sorter  25  in which a plurality of coin sorting holes  21  for sorting coins  300  according to sizes of the coins  300  are formed in a circumferential direction and a coin separation plate  28  on which a coin guider  26  for guiding coins to the coin sorter  25  is formed. 
     The defective coin discharge unit  30  is installed on the coin guider  26  of the coin separation unit  20  to detect whether a coin moving to be sorted is defective and sort a defective coin (not illustrated). 
     The coin supply unit  50  is installed on a central portion of the coin separation plate  28  to supply coins to be sorted so that the coins to be sorted move along the coin guider  26 . 
     The coin transfer unit  70  elastically comes in close contact with the coin separation plate  28 , causes the coins  300  input from the coin supply unit  50  to come in close contact with the coin separation plate  28 , and in this state, moves the coins  300  to the coin guider  26  and the coin sorting holes  21 . 
     The coin loading and change discharge unit  100  is installed on the support frame  11  and is installed on a lower surface of the coin separation plate  28  that corresponds to the coin sorting holes  21  of the coin sorter  25  in order to load the sorted coins  300  in coin recovery containers  101  and count the coins  300  and to dispense change using the loaded coins  300 . 
     The coin separation unit  20  includes the coin separation plate  28  in which the plurality of coin sorting holes  21  for sorting the coins  300  according to the sizes of the coins  300  are arranged and formed in the circumferential direction. The coin guider  26  configured to guide the coins  300  so that the coins  300  move along the coin sorting holes  21  arranged in the circumferential direction is formed on an upper portion of the coin separation plate  28 . 
     The coin separation plate  28  is fixed to an upper surface of the support frame  11  and fixed to an upper portion of the support frame  11 , but the present disclosure is not limited thereto, and the coin separation plate  28  may be integrally formed with the support frame  11 . Also, a rotary disc installation portion  22  on which a rotary disc  51  of the coin supply unit  50  that will be described below is positioned is formed on a central portion of the coin separation plate  28 . 
     The coin sorting holes  21  formed in the coin separation plate  28  are arranged and installed in the circumferential direction, and in order to allow coins with a smaller diameter to be discharged first, the coin sorting holes  21  are formed to have sizes that gradually increase in a counterclockwise direction. The coin sorting holes  21  are formed as many as the number that corresponds to the number of types (number of different values) of coins used in a country where the coin counting device will be installed. 
     A sorting guide member  29  for guiding the coins that have passed through the coin sorting holes  21  is installed on a lower surface of the coin separation plate  28 . In the sorting guide member  29 , holes  29   a  identical to the coin sorting holes  21  and corresponding thereto are formed, and a guide rib  29   b  which extends downward to guide coins to a coin recovery container which will be described below is formed on an edge of the hole  29   a.    
     Also, a first guide member  127  configured to allow an edge of the coin  300  moving along the coin guider  26  and an edge of the coin sorting hole  21  to match each other is installed on an inner side of the coin guider  26  of the coin separation plate  28 , and a second guide member  128  which is spaced apart from the first guide member  127  and has a length extending in the circumferential direction so that the coin  300  moving in the circumferential direction along the coin guider  26  comes in contact therewith is installed on the coin guider  26  in which a coupling hole  34  is formed. 
     The coin  300  moving along the coin guider  26  is guided by the first guide member  127  and the second guide member  128  and moves to the coin sorter  25 . 
     Meanwhile, a portion of an inner side surface of the first guide member  127  has a trajectory that matches an edge of the rotary disc installation portion  22 , and a portion of the first guide member  127  expands outward to form a discharge guider  127   a  for guiding the coin  300  to the coin guider  26 . 
     The coin supply unit  50  includes the rotary disc  51  installed on the rotary disc installation portion  22  to push a coin outward by a centrifugal force. Also, a rotary disc driving motor  55  for rotating the rotary disc  51  is installed on a lower surface of the coin separation plate  28  or the support frame  11 , and a driving shaft of the rotary disc driving motor  55  passes through the rotary disc installation portion  22  to be coupled to the rotary disc  51 . Also, a coin input hopper member  57  which surrounds the rotary disc and has a coin inlet  56  formed in an upper portion to allow coins to be input is installed on the support frame  11  or the coin separation plate  28 . A lower surface of the coin input hopper member  57  is supported by the first guide member  127  so that a coin outlet  26   a  is partitioned by the first guide member  127  and the coin input hopper member  57 . 
     The defective coin discharge unit  30  is installed between the coin outlet  26   a  and the coin sorter  25  and includes a coin identifier  33  which is installed on the coin guider  26  and includes first and second inductors  31  and  32  and a discharge door  42  which is configured to discharge a defective coin detected from the coin identifier  33  from the coin guider  26  before the defective coin enters the coin sorter  25 . 
     The coin identifier  33  is coupled to the coupling hole  34 , which is formed in the coin guider  26  of the coin separation plate  28 , to form a portion of the coin guider  26  and has a coin guide plate member  35  on which the first and second inductors  31  and  32  are installed provided on a lower portion thereof. A circuit board  36  connected to the first and second inductors  31  and  32  is installed on a lower surface of the coin guide plate member  35 . 
     The coin identifier  33  uses a RLC resonance circuit and is formed of a structure that detects a change in a frequency band. 
     The coin identifier  33  may include: a RLC resonance circuit which includes an AC power supply, a resistor, a capacitor, and the inductors  31  and  32 ; and a detector which includes a signal measurer configured to measure an analog signal output from the RLC resonance circuit and a signal processor configured to convert the analog signal measured in the signal measurer into a frequency band. 
     Although not illustrated, the RLC resonance circuit may consist of: a first circuit in which one side is linked to the AC power supply and connected to a first resistor and a first capacitor and the other end is connected to the first inductor  31 ; and a second circuit in which one side is linked to the AC power supply and connected to a second resistor and a second capacitor and the other end is connected to the second inductor  32 . 
     The detector may be provided as a plurality of detectors, and the plurality of detectors may be respectively connected to the first circuit and the second circuit and may convert an analog signal, each measured while a coin passes the first inductor  31  or the second inductor  32 , into a frequency band and transmit frequency change information to the controller. 
     Referring to  FIGS.  3 ,  6 , and  7   , the first inductor  31  and the second inductor  32  are disposed on a path along which a coin passes. The first inductor  31  is installed at a position more adjacent to the first guide member  127  than to the second guide member  128  between the coin outlet  26   a  and the second inductor  32 . Also, the second inductor  32  is installed at a position more adjacent to the second guide member  128  than to the first guide member  127  between the first inductor  31  and the coin sorter  25 . 
     Due to the position of the first inductor  31 , as a coin passes along the coin guider  26  while in contact with the second guide member  128 , an area in which the coin overlaps the first inductor  31 , that is, an area of the first inductor  31  covered by the coin, always changes according to the type (diameter size) of coin or whether the coin is bent. 
     Also, a coin moving along the coin guider  26  while in contact with the second guide member  128  always covers the entire second inductor  32  while passing during a predetermined amount of time regardless of the type of coin or whether the coin is defective, but the time during which the coin overlaps the second inductor  32  may vary according to whether the coin is defective. Here, a defective state of a coin may include a bent state, a crushed state, and a broken state. 
     Meanwhile, as an area in which a coin overlaps the first inductor  31  or the second inductor  32  increases and then decreases while the coin moves along the coin guider  26 , a frequency output from the coin identifier  33  may be changed. 
       FIGS.  8  and  9    are linear graphs showing changes in output frequencies according to an area in which a coin made of a nonferrous material overlaps the first and second inductors  31  and  32  while the coin passes the first and second inductors  31  and  32 . 
     In a case in which a coin is made of a nonferrous material, while the coin passes the first and second inductors  31  and  32 , a frequency increases and then decreases as illustrated. In a case in which a coin is made of a ferrous material, although not illustrated, a frequency decreases and then increases. Also, in a case in which a coin is made of a material in which ferrous and nonferrous materials are mixed, a frequency may repeat increasing and decreasing or may repeat decreasing and increasing. 
     Among the frequency change information transmitted from the detector, the controller may derive a maximum or minimum frequency value f 1  output while a coin passes the first inductor and a maximum or minimum frequency value f 2  output while the coin passes the second inductor. That is, the maximum frequency value f 1  or the minimum frequency value f 2  is a frequency shown when the coin maximally covers the first inductor  31  or the second inductor  32  while passing the first and second inductors  31  and  32 . 
     Specifically, the controller may be set to derive the maximum frequency value in a case in which a frequency gradually increases and then decreases while a coin passes the first and second inductors  31  and  32  and may be set to derive the minimum frequency value in a case in which a frequency gradually decreases and then increases while the coin passes the first and second inductors  31  and  32 . Also, the controller may be set to derive the maximum frequency value in a case in which a frequency repeats increasing and decreasing. That is, in a case in which a coin passing the first and second inductors  31  and  32  is made of a nonferrous material, the controller derives the maximum frequency value, in a case in which the coin is made of a ferrous material, the controller derives the minimum frequency value, and in a case in which the coin is made of a material in which ferrous and nonferrous materials are mixed, the controller derives the maximum frequency value. 
     Also, the controller may measure an amount of time w from a point in time at which a frequency increases when a coin passes the second inductor  32  until the frequency returns to a reference frequency. Here, the reference frequency is a frequency output from the detector connected to the second inductor  32  before a coin overlaps the second inductor  32 . Referring to  FIG.  9   , the amount of time w corresponds to a width from a point in time at which a frequency increases until the frequency returns to the reference frequency in the linear graph of changes in frequencies with time. 
     The maximum or minimum frequency value f 1  generated when a coin passes the first inductor  31  may be classified into a maximum or minimum frequency value output while a normal coin passes the first inductor  31  in a reference data obtaining operation of a coin identifying method which will be described below and a maximum or minimum frequency value f 1  output while a coin to be identified passes the first inductor  31  in a coin type and defect identifying operation of the coin identifying method which will be described below. 
     Also, the maximum or minimum frequency value f 2  generated when a coin passes the second inductor  32  may be classified into a maximum or minimum frequency value f 2 ′ output while a normal coin passes the second inductor  32  in the reference data obtaining operation and a maximum or minimum frequency value f 2 ″ output while a coin to be identified passes the second inductor  32  in the coin type and defect identifying operation of the coin identifying method which will be described below. 
     Also, a width value w from a point in time at which a frequency increases until the frequency returns to the reference frequency may be classified into a width value w′ when a normal coin passes the second inductor  32  in the reference data obtaining operation and a width value w when a coin to be identified passes the second inductor  32  in the coin type and defect identifying operation. 
     In the controller, the maximum or minimum frequency value f 1 ′ output while each normal coin passes the first inductor  31  is set as a first reference value, the maximum or minimum frequency value f 1 ″ output while each normal coin passes the second inductor  32  is set as a second reference value, and the width value w′ from a point in time at which a frequency increases when each normal coin passes the second inductor  32  until the frequency returns to the reference frequency is set as a third reference value. 
     In the controller, the first to third reference values transmitted and derived as the same type of normal coin is repeatedly input 20 times or more to the coin counting device  1  may be repeatedly stored, and ranges of the first to third reference values may be learned for each type of normal coin. 
     Also, in the controller, through the frequency change information transmitted from the detector, comparison target value data is obtained in which the maximum or minimum frequency value f 2 ′ output while a coin to be identified passes the first inductor  31  is set as a first measurement value, the maximum or minimum frequency value f 2 ″ output while a coin to be identified passes the second inductor  32  is set as a second measurement value, and the width value w″ from a point in time at which a frequency increases when a coin to be identified passes the second inductor  32  until the frequency returns to the reference frequency is set as a third measurement value. 
     The controller compares the first measurement value with the first reference value or the range of the first reference value for each type of normal coin, compares the second measurement value with the second reference value or the range of the second reference value for each type of normal coin, compares the third measurement value with the third reference value or the range of the third reference value for each type of normal coin, simultaneously determines the type of coin to be identified and whether the coin to be identified is defective, and controls opening and closing of the discharge door  42 . Detailed description thereof will be given below in description of a method of identifying a defective coin according to the present disclosure. 
     Meanwhile, the discharge door  42  forms a defective coin outlet  41  in the coin guider  26 . The discharge door  42  forms a portion of the coin guider  26  and is configured to, when a defective coin moves, open the defective coin outlet  41  to allow the defective coin to be discharged and, when a normal coin moves, close the defective coin outlet  41  so that the coin  300  moves to the coin sorter  25 . 
     The opening and closing of the discharge door  42  are performed by a door opening/closing driver  45 . Although not illustrated in detail, the door opening/closing driver  45  may be driven by a link operated by a solenoid connected to the controller. 
     Meanwhile, the coin transfer unit  70  includes a ring gear  72  rotatably installed by being guided to an inner circumferential surface of a guide ring  71  forming the support frame  11  on an upper portion of the coin separation plate  28  supported by the support frame  11 , a driving motor  74  installed on the support frame  11  and the coin separation plate  28 , and a driving gear  75  installed on a driving shaft of the driving motor  74  and engaged with the ring gear  72 . 
     Also, the coin loading and change discharge unit  100  has a structure in which coins  300  sorted by the coin separation unit  20  are loaded in the coin recovery containers  101  and the coins loaded in the coin recovery containers  101  are discharged to dispense change. 
     As structures of the door opening/closing driver  45 , the coin transfer unit  70 , and the coin loading and change discharge unit  100 , structures disclosed in Korean Patent Registration No. 10-2203230 (coin counting device) filed by the present applicant may be applied, and detailed descriptions thereof will be omitted. 
     Hereinafter, a coin identifying method according to an embodiment of the present disclosure that uses the coin counting device  1  having the structure described above will be described. 
     Referring to  FIGS.  5  to  9   , the coin identifying method according to an embodiment of the present disclosure includes a reference data obtaining operation (S 001 ) and a coin type and defect identifying operation (S 003 ). 
     The reference data obtaining operation (S 001 ) is an operation in which different types of normal coins are input to the coin counting device  1  to store the maximum or minimum frequency value f 1 ′, which is output while a normal coin passes the first inductor  31  of the coin identifier  33  installed on the coin guider  26  extending in the circumferential direction, as a first reference value, store the maximum or minimum frequency value f 2 ′, which is output while a normal coin passes the second inductor  32 , as a second reference value, and store the width value w′ of a linear graph of changes in frequencies from a point in time at which a frequency changes when a normal coin passes the second inductor  32  until the frequency returns to the reference frequency as a third reference value, thus obtaining identification reference value data for each type of normal coin. 
     In the reference data obtaining operation (S 001 ), first to third reference values derived by inputting the same type of normal coin 20 times or more to the coin counting device may be repeatedly stored to obtain identification reference value data for each type of normal coin. That is, the identification reference value data includes information on a first reference value range, a second reference value range, and a third reference value range for each type of normal coin. 
     The coin type and defect identifying operation (S 003 ) is an operation in which the maximum or minimum frequency value f 1 ″ output while a coin to be identified, which is input to the coin counting device  1 , passes the first inductor  31 , the maximum or minimum frequency value f 2 ″ output while the coin to be identified passes the second inductor  32 , and the width value w″ of a linear graph of changes in frequencies from a point in time at which a frequency changes while the coin to be identified passes the second inductor  32  until the frequency returns to the reference frequency are compared with the identification reference value data to simultaneously determine a type of the coin to be identified and whether the coin to be identified is defective. 
     The coin type and defect identifying operation (S 003 ) may include: a comparison data obtaining operation in which the maximum or minimum frequency value f 1 ″ output while a coin to be identified passes the first inductor  31  is stored as a first measurement value, the maximum or minimum frequency value f 2 ″ output while the coin to be identified passes the second inductor  32  is stored as a second measurement value, and the width value w″ of a linear graph of changes in frequencies from a point in time at which a frequency changes while the coin to be identified passes the second inductor  32  until the frequency returns to the reference frequency is stored as a third measurement value in order to obtain comparison target value data; and a determining operation in which the first measurement value is compared with the first reference value or the range of the first reference value for each type of normal coin, the second measurement value is compared with the second reference value or the range of the second reference value for each type of normal coin, the third measurement value is compared with the third reference value or the range of the third reference value for each type of normal coin, and whether a value corresponding to the ranges which include the first to third measurement values or a value corresponding to the first to third measurement values is present in the identification reference value data is determined to simultaneously determines the type of coin to be identified and whether the coin to be identified is defective. 
     The determining operation may include a first determining operation in which the first measurement value and the second measurement value are compared with the first and second reference values or the ranges of the first and second reference values of the identification reference value data to primarily determine the type of coin to be identified and a second determining operation in which the third reference value of the normal coin, which corresponds to the type of coin to be identified determined in the first determining operation, is compared with the third measurement value or the range of the third measurement value to finally determine the type of coin to be identified and whether the coin to be identified is defective. 
     Meanwhile, diameters and materials differ for each type of normal coin. For example, among the Korean coins, the ten-won coin has a diameter of 18 mm and is made up of 48% copper and 52% aluminum, a fifty-won coin has a diameter of 21.6 mm and is made up of 70% copper, 18% zinc, and 12% nickel, a hundred-won coin has a diameter of 24 mm and is made up of 75% copper and 25% nickel, and a five-hundred-won coin has a diameter of 26.5 mm and is made up of 75% copper and 25% nickel. 
     Accordingly, for each type of normal coin, an area overlapping the first inductor  31  is different, and even among the same type of coins, an area overlapping the first inductor  31  is different according to whether a coin is defective, e.g., bent. Also, the time during which a coin to be identified passes the second inductor  32  may vary according to whether the coin is defective, e.g., bent. 
     Therefore, according to the type and material of a coin to be identified and whether the coin to be identified is defective, the maximum or minimum frequency value f 1 ″ output while the coin to be identified passes the first inductor  31 , the maximum or minimum frequency value f 2 ″ output while the coin to be identified passes the second inductor  32 , and the width value w″ of a linear graph of changes in frequencies from a point in time at which a frequency changes while the coin to be identified passes the second inductor  32  until the frequency returns to the reference frequency are each derived differently. 
     The diameter of the coin to be identified may be determined through the maximum or minimum frequency value f 1 ″ output while the coin to be identified passes the first inductor  31 , and the type of the coin to be identified may be determined by determining the material of the coin to be identified through the maximum or minimum frequency value f 2 ″ output while the coin to be identified passes the second inductor  32 . 
     Also, whether the coin to be identified is defective may be determined through the width value w″ of the linear graph of changes in frequencies from a point in time at which a frequency changes while the coin to be identified passes the second inductor  32  until the frequency returns to the reference frequency. 
     The tables below are examples. Table 1 shows ranges of the first to third reference values derived by each type of normal coin repeatedly passing the first and second inductors  31  and  32 , and Table 2 shows a summary of results of simultaneously determining the type of coin and whether the coin is defective through the first to third measurement values while coins to be identified pass the first and second inductors  31  and  32 . 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 f 1 ′ 
                 f 2 ′ 
                 w′ 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 Normal coin 1 
                 2.89-3.12 
                 4.95-5.12 
                 3.95-4.15 
               
               
                   
                 Normal coin 2 
                 1.88-2.14 
                 4.95-5.12 
                 1.95-2.15 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                   
                   
                   
                 Results of 
               
               
                   
                 f 1 ″ 
                 f 2 ″ 
                 w″ 
                 determining 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 Coin to be 
                 3.05 
                 5.00 
                 3.98 
                 Normal coin 1 
               
               
                   
                 identified 1 
               
               
                   
                 Coin to be 
                 3.10 
                 5.05 
                 3.40 
                 Defective 
               
               
                   
                 identified 2 
               
               
                   
                 Coin to be 
                 2.08 
                 4.96 
                 3.01 
                 Defective 
               
               
                   
                 identified 3 
               
               
                   
                   
               
            
           
         
       
     
     Since the first to third measurement values of the coin to be identified  1  respectively fall within the ranges of the first to third reference values of the normal coin  1 , the coin to be identified  1  is determined as the normal coin  1 . 
     The coin to be identified  2  may be primarily determined as the same type of the normal coin  1  when, in the first determining operation, only the first measurement value, which is the maximum or minimum frequency value f 1 ″ output while the coin passes the first inductor  31 , and the second measurement value, which is the maximum or minimum frequency value f 2 ″ output while the coin passes the second inductor  32 , are compared. However, since, in the second determining operation, the third measurement value of the coin to be identified  2  deviates from the range of the third reference value of the normal coin  1 , the coin to be identified  2  is determined as a defective coin and may be a different type of coin from the normal coin  1 . 
     The coin to be identified  3  may be primarily determined as the same type of the normal coin  2  due to the first and second measurement values each falling within the ranges of the first and second reference values of the normal coin  2 . However, since the third measurement value of the coin to be identified  3  deviates from the range of the third reference value of the normal coin  2 , the coin to be identified  3  is determined as a defective coin and may be a different type of coin from the normal coin  2 . 
     In this way, in a case in which a coin to be identified is a defective coin which is bent, the maximum or minimum frequency value f 1 ″, that is, the first measurement value, differs when the coin moves along the coin guider while a bent portion of the coin overlaps the first inductor  31  and when the coin moves along the coin guider while a normal portion of the coin overlaps the first inductor  31 . 
     Therefore, the type of coin to be identified may be erroneously determined when just the maximum or minimum frequency value f 1 ″ output while the coin to be identified passes the first inductor  31  and the maximum or minimum frequency value f 2 ″ output while the coin to be identified passes the second inductor  32  are used. 
     Accordingly, the type of coin to be identified and whether the coin to be identified is defective may be finally determined by comparing the identification reference value data with the maximum or minimum frequency value f 1 ″ output while the coin to be identified passes the first inductor  31 , the maximum or minimum frequency value f 2 ″ output while the coin to be identified passes the second inductor  32 , and the width value w″ of the linear graph of changes in frequencies from a point in time at which a frequency changes until the frequency returns to the reference frequency. 
     In a case in which a decimal part is present in the first to third measurement values, the controller may round off the numbers to certain decimal places in the decimal part of the first to third measurement values to compare the first to third measurement values with the ranges of the first to third reference values. For example, the controller may round off the numbers to three decimal places or four decimal places in the decimal part of the first to third measurement values to compare the first to third measurement values with the ranges of the first to third reference values. 
     In this way, in the coin identifying method according to an embodiment of the present disclosure, the first to third measurement values of the coin to be identified are compared with the first to third reference values of each normal coin, and when the coin to be identified passes the first and second inductors  31  and  32 , whether a normal coin whose ranges of the first to third reference values include the first to third measurement values of the coin to be identified is present is determined, and when a normal coin satisfying all the conditions is not present, the coin to be identified is determined as a defective coin. 
     Meanwhile, different from the example presented above, average values of first reference values, second reference values, and third reference values which are derived by inputting the same normal coin 20 times or more to the coin counting device  1  may be compared with the first to third measurement values. In this case, the controller may calculate an average value of first reference values, an average value of second reference values, and an average value of third reference values for each type of normal coin and may set error ranges for the average values of the first to third reference values for each type of normal coin to determine whether the measured first to third measurement values are within the set error ranges, thus simultaneously determining the type of coin to be identified and whether the coin to be identified is defective. 
     In the coin identifying method according to an embodiment of the present disclosure which has been described above, since the maximum or minimum frequency value f 1 ″ output while the coin to be identified passes the first inductor  31 , the maximum or minimum frequency value f 2 ″ output while the coin to be identified passes the second inductor  32 , and the width value w″ of the linear graph of changes in frequencies from a point in time at which a frequency changes while the coin to be identified passes the second inductor until the frequency returns to the reference frequency are compared with the first to third reference values set for each type of normal coin to simultaneously determine the type of coin and whether the coin is defective, there is an advantage that efficiency and reliability of identification can be improved. 
     Meanwhile,  FIG.  10    illustrates a block diagram of a coin identifying method according to another embodiment of the present disclosure. 
     In order to improve reliability of identifying a coin and determining whether the coin is defective, the coin identifying method according to another embodiment of the present disclosure further includes a coin type and defect reidentifying operation (S 005 ) and a checking operation (S 007 ). 
     A coin counting device of the coin identifying method according to another embodiment of the present disclosure further includes an auxiliary coin identifier. The auxiliary coin identifier has the same configuration as the above-described coin identifier  33  and includes a third inductor (not illustrated) positioned on the same circumferential trajectory line as the first inductor  31  between the coin identifier and the discharge door  42  and a fourth inductor (not illustrated) positioned on the same circumferential trajectory line as the second inductor  32 . Detailed descriptions thereof will be omitted. 
     The coin type and defect reidentifying operation (S 005 ) may include an auxiliary comparison data obtaining operation in which first to third auxiliary measurement values derived while a coin to be identified, which has passed the coin identifier  33 , passes the auxiliary coin identifier (not illustrated) are obtained, and an auxiliary determining operation in which first to third reference values for each type of normal coin are compared with the first to third auxiliary measurement values to simultaneously redetermine the type of coin to be identified and whether the coin to be identified is defective. 
     The controller compares a first auxiliary measurement value, which is a maximum or minimum frequency value output while the coin to be identified passes the third inductor of the auxiliary coin identifier, a second auxiliary measurement value, which is a maximum or minimum frequency value output while the coin to be identified passes the fourth inductor of the auxiliary coin identifier, and a third auxiliary measurement value, which is a width value of a linear graph of changes in frequencies from a point in time at which a frequency changes while the coin to be identified passes the fourth inductor until the frequency returns to the reference frequency, with the first to third reference values for each type of normal coin to simultaneously redetermine the type of coin to be identified and whether the coin to be identified is defective. 
     The auxiliary determining operation may include a third determining operation in which the first auxiliary measurement value and the second auxiliary measurement value are compared with the range of the first reference value and the range of the second reference value for each normal coin to redetermine the type of coin to be identified and a fourth determining operation in which the range of the third reference value of the normal coin, which corresponds to the type of coin to be identified determined in the third determining operation, is compared with the third auxiliary measurement value to finally determine the type of coin to be identified and whether the coin to be identified is defective. 
     The checking operation (S 007 ) is an operation in which the coin to be identified is finally determined as a defective coin when any one of a primary identification result and a secondary identification result indicates that the coin to be identified is determined as a defective coin. That is, the controller of the coin counting device controls opening and closing of the discharge door  42  so that the defective coin outlet  41  is opened when any one of the primary identification result and the secondary identification result indicates that the coin to be identified is determined as a defective coin. 
     In the coin identifying method according to another embodiment of the present disclosure, since a coin to be identified is identified primarily and secondarily to determine the type of coin and whether the coin is defective, reliability can be further improved. 
     According to a coin identifying method of the present disclosure, since a maximum or minimum frequency value output while a coin to be identified passes a first inductor, a maximum or minimum frequency value output while the coin to be identified passes a second inductor, and a width value of a linear graph of changes in frequencies from a point in time at which a frequency changes while the coin to be identified passes the second inductor until the frequency returns to a reference frequency are compared with reference values set for different types of normal coins in order to simultaneously determine a type of the coin to be identified and whether the coin to be identified is defective, there is an advantage in that efficiency and reliability of identification can be improved. 
     A coin identifying method of the present disclosure has been described above with reference to embodiments illustrated in the drawings, but the above embodiments are merely illustrative, and those of ordinary skill in the art should understand that various modifications and other equivalent embodiments are possible from the above embodiments. Therefore, the true technical scope of the present disclosure should be defined by the technical spirit of the appended claims.