Abstract:
A charger calibrating device and a calibrating method thereof. The device comprises a control module and a processing module. The control module controls a charger to be calibrated to perform a first stage charging and a second stage charging on an electronic device. The processing module performs an adjusting process according to the second stage charging time for adjusting the high level period of the PWM signal in the charging circuit of the charger. In the adjusting process, generating an updated high level period by adding or decreasing a preset adjusting amplitude, and decrease the preset adjusting amplitude by half to generate an updated adjusting amplitude. The processing module terminates the calibrating process after repeating the aforementioned calibrating loop a preset number of times.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of priority to Taiwan Patent Application No. 100135178, filed on Sep. 29, 2011, in the Taiwan Intellectual Property Office, the disclosure of which is incorporated in its entirety by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a charger calibrating device, in particular to a digital flash lamp charger calibrating device and a calibrating method thereof with a lower cost and a higher efficiency. 
     2. Description of the Related Art 
     In digitals camera and digital camcorders, a flash lamp module is a necessary component, and a flash lamp circuit requires a charging capacitor to store energy in order to trigger an inert gas inside a lamp tube of a flash lamp to emit light. Such capacitor generally has a charging voltage up to 300 volts. To achieve a high voltage of over 300 volts for the capacitor voltage, the flash lamp circuit generally comes with a charging circuit to convert and supply the electric energy of a battery into the capacitor. 
     During the production process of a camera, a maximum flash lamp charging time is set to comply with a specific technical specification for all produced cameras, such that each camera has substantially the same charging time under the condition of the same voltage. In general, a flyback converter is usually used as the charging circuit of a camera. 
     With reference to  FIG. 1  for a schematic circuit diagram of a charging circuit of a conventional flash lamp charger, the flyback converter  1  controls the ON/OFF of an n-type metal oxide semiconductor Q 1  by a pulse width modulation (PWM) circuit P 1  and charges a capacitor by an inductor in the circuit. If the PWM circuit P 1  is situated in a high level period, a gate of the semiconductor Q 1  is situated at a high level and an ON state for charging the inductor of a primary side n p  of a transformer T 1 . 
     On the contrary, it is an OFF sate if the gate of the semiconductor Q 1  is situated at a low level. At the same time, a secondary side n s  of the transformer T 1  will induce a current, and the current flows through a diode D 1  to charge a capacitor C 1 , and the inductance of the primary side n p  of the transformer will convert and transfer the energy stored at the gate of the semiconductor Q 1  during in the high level period to the capacitor C 1 . Therefore, the voltage of the capacitor C 1  can be charged to a level over 300 volts by continuous switching the semiconductor Q 1 . 
     However, hardware components have errors, such as the inductance of the primary side n p  may have an error of +/−20%. Since the semiconductor Q 1  is situated at the ON state, the current passing through the primary side n p  will increase with time. The smaller the inductance, the faster is the rising current. On the contrary, the larger the inductance, the slower is the rising current. Therefore, the error of the inductance will affect the charging time of the flyback converter. To avoid the aforementioned situation, related manufacturers generally install a resistor R 3  in the flyback converter, that monitoring and control the current passing through the primary side n p  by a comparator CP 1 . When the current rises to a certain level, the resistor R 3  will have a voltage value greater than threshold voltage value (Vth). Now, the PWM circuit P 1  turns off the semiconductor Q 1  and terminates the continual charging of the inductor of the primary side n p  to control the charging time of the capacitor C 1 . 
     This method requires additional resistor R 3  and comparator CP 1  installed in the circuit and incurs a higher cost. In addition, the resistor R 3  will generate heat and lower the efficiency of the charger. Therefore, it is a main subject for the present invention to design a flash lamp charger calibrating device capable of lowering the manufacturing cost of the flash lamp charger, improving the charging efficiency, and enhancing the production capacity and yield rate of camera or camcorder products. 
     SUMMARY OF THE INVENTION 
     Therefore, it is a primary objective of the present invention is to overcome the shortcomings of the prior art by providing a charger calibrating device and a calibrating method thereof to achieve the effects of lowering the manufacturing cost, improving the charging efficiency, and enhancing the production capacity, yield rate and manufacturing labor and time of camera or camcorder products. 
     To achieve the aforementioned objective, the present invention provides a charger calibrating device, the charger calibrating device comprises a control module and a processing module. The control module is arranged for controlling a charger to be calibrated to execute a first stage charging and a second stage charging to an electronic device, and then controlling the electronic device to execute a discharging process. The processing module is arranged for executing an adjusting process to add or subtract a preset adjusting amplitude in a predetermined high level period of a switch in a charging circuit of the charger to be calibrated to generate an updated high level period if a second stage charging time is greater than or smaller than a typical charging time, and then producing an updated adjusting amplitude after the updated high level period is generated. The predetermined high level period and the preset adjusting amplitude are substituted by the updated high level period and the updated adjusting amplitude respectively, and terminate the calibrating process until the aforementioned calibrating loop is repeated for a predetermined number of times. 
     To achieve the aforementioned objective, the present invention further provides a charger calibrating method, comprising the steps of: using a control module to control a charger to be calibrated to execute a first stage charging and a second stage charging to an electronic device; using the control module to control the electronic device to execute a discharging process; Executing an adjusting process by the processing module if a second stage charging time is greater than or smaller than a typical charging time, and adding or subtracting the predetermined high level period from a preset adjusting amplitude in a predetermined high level period of a switch in a charging circuit of the charger to be calibrated to generate an updated high level period, and then reducing the preset adjusting amplitude by half to generate an updated adjusting amplitude; using the processing module to substitute the predetermined high level period and the preset adjusting amplitude by the updated high level period and the updated adjusting amplitude respectively, and terminating the calibrating process when the aforementioned calibrating loop is repeated for a predetermined number of times. 
     In an embodiment, a determination module may be provided for terminating the calibrating process when an error condition or a termination condition occurs. 
     In an embodiment, a fine-tune module may be provided for determining whether the second stage charging time is matched with a fine-tune condition when the first calibrating loop is executed; executing a fine-tune procedure if the second stage charging time is matched with a fine-tune condition, and performing an adjusting process; executing a table lookup analysis procedure if the second stage charging time is not matched with a fine-tune condition, and performing an adjusting process. 
     In an embodiment, the fine-tune procedure may reduce the preset adjusting amplitude to generate a fine-tune adjustment amplitude to substitute the preset adjusting amplitude. 
     In an embodiment, the table lookup analysis procedure may be looking up an inductance of a transformer in a charging circuit and an estimated high level period by a table lookup according to the second stage charging time, and when entering into the adjusting process of a next calibrating loop, substitutes the updated high level period by the estimated high level period, and reducing the adjustment amplitude to substitute the updated adjusting amplitude at the same time. 
     In an embodiment, the discharging process may perform a full discharge or a partial discharge to an electronic device, wherein the voltage after the discharge is smaller than a first stage saturation voltage. 
     In an embodiment, the processing module may decrease the preset adjusting amplitude by half to generate an updated adjusting amplitude. 
     To achieve the objective, the present invention further provides a charger calibrating device, the charger calibrating device comprises a control means, an adjustment means and a repeated substitution means. The control means is arranged for controlling a charger to be calibrated to execute a first stage charging and a second stage charging to an electronic device, and controlling the electronic device to execute a discharging process. The adjustment means is arranged for adding or subtracting a preset adjusting amplitude in a predetermined high level period of a switch in a charging circuit of the charger to be calibrated to generate an updated high level period if a second stage charging time is greater or smaller than a typical charging time, and reducing the preset adjusting amplitude by half to generate an updated adjusting amplitude. The repeated substitution means is arranged for substituting the predetermined high level period and the preset adjusting amplitude by the updated high level period and the updated adjusting amplitude respectively, and terminating the calibrating process when the aforementioned calibrating loop is repeated for a predetermined number of times. 
     In an embodiment, a determination means may be provided for terminating the calibrating process when an error condition or a termination condition occurs. 
     In an embodiment, a fine-tune means may be provided for determining whether the second stage charging time is matched with a fine-tune condition when the first calibrating loop is executed; Executing a fine-tune procedure if the second stage charging time is matched with a fine-tune condition, and performing an adjusting process; executing a table lookup analysis procedure if the second stage charging time is not matched with a fine-tune condition, and performing an adjusting process. 
     In an embodiment, the adjustment means may decrease the preset adjusting amplitude by half to generate an updated adjusting amplitude. 
     In summary, the charger calibrating device and the calibrating method in accordance with the present invention have one or more of the following advantages: 
     (1) The charger calibrating device and calibrating method can execute the charger calibrating process efficiently without the need of installing any electronic device in the charger, so as to save the manufacturing cost of the charger. 
     (2) The charger calibrating device and calibrating method can execute the charger calibrating process quickly to reduce the production time of the electronic product effectively. 
     (3) The charger calibrating device and calibrating method can check any defect produced quickly during the production process of the electronic products, and calibrate the charger effectively, so as to improve the production capacity and the yield rate of the electronic products effectively. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic circuit diagram of a charging circuit of a conventional flash lamp charger; 
         FIG. 2  is a block diagram of a charger calibrating device in accordance with a preferred embodiment of the present invention; 
         FIG. 3  is a flowchart of a charger calibrating device in accordance with a preferred embodiment of the present invention; 
         FIG. 4  is a block diagram of a charger calibrating device in accordance with a second preferred embodiment of the present invention; 
         FIGS. 5A and 5B  show a flow chart of a charger calibrating device in accordance with a second preferred embodiment of the present invention; 
         FIG. 6  is a table lookup of a charger calibrating device in accordance with a preferred embodiment of the present invention; 
         FIGS. 7A and 7B  show a time comparison flowchart of a calibrating process of a charger calibrating device in accordance with a preferred embodiment of the present invention; and 
         FIG. 8  is a flowchart of a charger calibrating method in accordance with a preferred embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The technical characteristics of the charger calibrating device and calibrating method of the present invention become apparent with the detailed description of preferred embodiments and the illustration of related drawings as follows. It is noteworthy to point out that same symbols are used in the following preferred embodiments to represent respective elements. 
     The charger calibrating device and calibrating method of the present invention are applicable to various electronic devices such as digital cameras and digital camcorders. To make it easier to understand the technical characteristics of the present invention, a digital camera is used as an embodiment for illustrating the present invention, but the invention is not limited to digital cameras only. 
     With reference to  FIG. 2  for the block diagram of the charger calibrating device in accordance with the first preferred embodiment of the present invention, the flash lamp charger calibrating device  2  comprises the processing module  21  and the control module  22 . Firstly, the processing module  21  executes an initial setup. Now, the flash lamp  24  has been discharged with the maximum amplitude, and the control module  22  will control the flash lamp charger  23  to charge the flash lamp  24 . Wherein, the charging is performed by two stages. In the first stage charging, a voltage of approximately 60V for a full flash of the flash lamp is charged to a voltage of 100V. In the second stage charging, the voltage of 100V is charged to 320V. After the second stage charging is finished, the control module  22  will control the flash lamp  24  to execute a full-flash discharge, such that the voltage of the flash lamp  24  returns to a level of approximately 60V. 
     In an embodiment, it is noteworthy to point out that manufacturers will list the flash lamp charging time as one of the technical specifications during the production process of the cameras, and thus the defined charging time is the time required for charging a voltage (approximately equal to 60V) of a flash lamp after the discharge of a full flash to a saturation voltage of 320V. The saturation voltage is the voltage (300V) of flash lamp sufficient for a full flash plus a safety range (20V). However, the required voltage varies with different cameras, so that a charging range required by the first stage charging and the second stage charging may cover the voltage for a full flash of the flash lamp to the saturation voltage of a normal rated flash. Therefore, the overall charging time calibrating process may perform a calibration within a complete voltage range as required by the technical specifications. 
     In an embodiment, after the flash lamp  24  is discharged, the processing module  21  will start executing the adjusting process to compare the calculated second stage charging time  232  with the typical charging time. If the second stage charging time  232  is greater than typical charging time, it may show that the inductance of a primary side winding of a transformer in a charging circuit of the flash lamp charger  23  is greater than a standard value, and a longer time is required for storing energy, so that it is necessary to increase the high level period of the switch in the charging circuit, wherein the switch can be a pulse width modulation (PWM) circuit. Now, the processing module  21  adds a preset adjusting amplitude (Ton Offset) to a predetermined high level period (Old Ton) to generate an updated high level period (New Ton). On the contrary, if the second stage charging time  232  is smaller than the typical charging time, the processing module  21  will subtract the preset adjusting amplitude from the predetermined high level period to generate an updated high level period. However, the processing module  21  will reduce the preset adjusting amplitude by half to generate an updated adjusting amplitude. In the general situation, the processing module  21  will repeat the aforementioned calibrating loop for a predetermined number of times which can be generally six or seven times. 
     In an embodiment, the flash lamp charger calibrating device  2  of the present invention no longer needs additional resistor and comparator installed in the charging circuit to achieve the calibrating effect, so as to lower the manufacturing cost of the camera. 
     With reference to  FIG. 3  for a flow chart of a charger calibrating device in accordance with the first preferred embodiment of the present invention, the operation comprises the following steps: 
     Step S 31 : Execute an initialize setup. 
     Step S 32 : Determine whether the number of times of executing a calibrating loop is equal to a predetermined number of times; if yes, then go to Step S 36  and terminate the calibrating process, or else go to Step S 33 . 
     Step S 33 : Execute a first stage charging and a second stage charging, and then discharge for a full flash. 
     Step S 34 : Determine whether the second stage charging time is greater than a typical charging time; if yes, then go to Step S 341 , or else go to Step S 342 . 
     Step S 341 : Calculate an updated high level period, wherein the updated high level period=a predetermined high level period+a preset adjusting amplitude. 
     Step S 342 : Calculate an updated high level period, wherein the updated high level period=a predetermined high level period−a preset adjusting amplitude. 
     Step S 35 : Calculate an updated adjusting amplitude, wherein the updated adjusting amplitude=a preset adjusting amplitude/2, and then return to Step S 32 . 
     With reference to  FIG. 4  for a block diagram of a charger calibrating device in accordance with a second preferred embodiment of the present invention, the flash lamp charger calibrating device  4  of the present invention comprises a processing module  41 , a control module  42 , a fine-tune module  45  and a determination module  46 . Similarly, the processing module  41  will execute an initial setup. The control module  42  will control a flash lamp charger  43  to perform a first stage charging and a second stage charging to a flash lamp  44  and control the flash lamp  44  to perform a partial discharge. 
     In an embodiment, it is noteworthy to point out that the discharge of the maximum amplitude no longer uses the full-flash for a flash lamp  44  in this preferred embodiment to achieve a higher efficiency of the flash lamp charger calibrating device  4 . In the calibrating process of the first preferred embodiment, the range of calibrating the charging time is a second stage charging, which means need a voltage of 220V to charged in the voltage range of 100V˜320V, so that it may take several seconds. In this preferred embodiment, the difference between the second stage saturation voltage and the first stage saturation voltage is maintained greater than 30V during the initial condition in order to reduce the charging time. In other words, approximately a voltage of 30V is charged in the second stage charging, and thus may improve the efficiency significantly. 
     In general, a digital camera requires a voltage of 250V for a normal flash, so that the second stage saturation voltage must be greater than 250V plus a safety range of 20V. Therefore, the second stage saturation voltage may be set to 270V, and the first stage saturation voltage may be set to 240V. 
     In an embodiment, it is noteworthy to point out that the full-flash may not use for discharge of the flash lamp  44  by calibrating the first and second stage saturation voltage. As long as the voltage is lower than the first stage saturation voltage after the flash lamp  44  is flashed, the first stage charging time  431  can be minimized as much as possible (which is the time required to charge the voltage after the flash lamp is flashed to the first stage saturation voltage). To avoid triggering an error condition (such as the first stage charging time  431  is smaller than the minimum first stage charging time), the first stage charging time  431  must be greater than the minimum first stage charging time plus some safety time to prevent errors of the charging time in the calibrating loop. On the other hand, the difference between the second stage saturation voltage and the first stage saturation voltage is preferably not smaller than 30V. If the difference is smaller than 30V, then the second stage charging time will have a too-small change, and a larger error may occur easily in the calibrating process. 
     The determination module  46  is provided for processing errors and terminating the calibrating process when the error condition  461  occurs, wherein the error condition  461  may comprise the following: 
     (1) The first stage charging time  431  is smaller than the minimum first stage charging time. Since the capacitor is discharged by the flash lamp  44 , the voltage of the capacitor may not be able to discharge electricity due to an abnormal circuit of the flash lamp  44  or a damaged lamp tube, so that the first stage charging time  431  becomes very short. A product with problems can be found by setting a minimum first stage time, and the calibrating process is terminated immediately. 
     (2) The second stage charging time  432  is smaller than the minimum second stage charging time. Errors may occur in the components such as a transformer, an inductor, a capacitor and a resistor in the charging circuit, but such errors still fall within the manufacturer&#39;s specification. By assembling the component with the largest error in advance, the minimum second stage charging time is set, and the calibrating process is terminated immediately to avoid wasting too much time on the cameras with problems when the second stage charging time  432  is smaller than the minimum second stage charging time. 
     (3) The second stage charging time  432  is greater than the maximum second stage charging time for the same reason as given above. 
     (4) After the calibrating process is finished, the first stage charging time  431  plus the second stage charging time  432  is still greater than the maximum total charging time. In the calibrating process, the charging time cannot reach the typical charging time +/−5% due to the charging time error, or a minor hardware problem (such as a leaked capacitor), but the process has not exceeded the maximum and minimum of the second stage charging time. After the calibrating process is finished, the calibration is considered to be failed if the first stage charging time  431  plus the second stage charging time  432  is still greater than the maximum total charging time. 
     (5) A hardware charging protection error occurs during the first stage charging and second stage charging processes. The design of the digital flash lamp charger provides several hardware protection mechanisms. As long as the hardware protection mechanism is triggered during the first stage charging and second stage charging process, the calibrating process will be terminated immediately to avoid meaningless calibration on a camera with problems, so as to pick the camera with problems quickly. 
     (6) A software charging protection error occurs during the first stage charging or second stage charging process. The design of the digital flash lamp charger will enable the software charging protection for the charging during the calibrating process, so as to enhance the protection mechanism. As long as the charging protection mechanism is trigger during the charging process, the calibrating process will be terminated immediately to avoid continuous calibration of the camera with problems, so as to pick the camera with problems quickly. 
     In an embodiment, the determination module  46  may terminate the calibrating process when a termination condition  462  occurs, and such termination condition  462  may include the following: 
     (1) The second stage charging time  432  falls in a range of the typical charging time +/−5%, and the first stage charging time  431  plus the second stage charging time  432  is smaller than the maximum total charging time. Since there is an error of the charging time, the second stage charging time  432  falls within the range of the typical charging time +/−5% is acceptable. This condition may be used to make a camera with a charging time very close to the typical charging time and capable of finishing the calibrating process within the shortest time. 
     (2) After the calibrating process is finished, the first stage charging time  431  plus the second stage charging time  432  is smaller than the maximum total charging time. In the calibrating process, the second stage charging time  432  cannot falls within the typical charging time +/−5% due to the charging time error, but the process has not exceeded the maximum and minimum of the second stage charging time. To let this camera pass the calibrating process and considered as a camera that can finish the calibrating process successfully, as long as the final first stage charging time  431  plus the second stage charging time  432  is maintained smaller than the maximum total charging time. 
     In an embodiment, when the fine-tune module  45  executes the first calibrating loop, the adjusting process is accelerated, and a determination can be made to check whether or not the second stage charging time  432  is matched with a fine-tune condition, wherein the fine-tune condition may be set freely according to the actual situation. In this preferred embodiment, the fine-tune condition occurs, when the second stage charging time  432  reaches the typical charging time +/−(5%˜8%). It shows that the second stage charging time  432  is very close to the typical charging time if the second stage charging time  432  is matched with the fine-tune condition, and the fine-tune procedure  451  is executed, and the preset adjusting amplitude is reduced (to 70 clocks in this preferred embodiment) to generate a fine-tune adjustment amplitude (which is one half of the preset adjusting amplitude in this preferred embodiment) to avoid a too-large adjustment, such that the calibrating loop has to be repeated for many times in order to calibrate too many errors at the first time. In other words, if the second stage charging time  432  falls within the typical charging time +/−(5%˜8%), a smaller adjustment amplitude is used for performing the fine-tune directly without performing any coarse adjustment, so as to finish the calibrating process more quickly. After the fine-tune procedure  451  is finished, the table lookup analysis procedure  452  is performed. 
     In an embodiment, if f the second stage charging time  432  is not matched with the fine-tune condition, it shows that the second charging time  432  is very different from the typical charging time, and the table lookup analysis procedure  452  will be executed. The table lookup analysis procedure  452  uses the previously created table lookup to find the corresponding inductance and the estimated high level period according to the second stage charging time  432 . In the next calibrating loop, when the processing module  41  executes the adjusting process  411 , the estimated high level period is used directly, while using the reduced adjustment amplitude (which is equal to 15 clocks in this preferred embodiment) to make adjustments, and calibrate the errors of other circuit components to shorten the calibrating process. 
     In an embodiment, the processing module  41  executes the adjusting process  411 . If the second stage charging time  432  is greater than the typical charging time and the fine-tune condition is matched, then the updated high level period=a predetermined high level period+a fine-tune adjustment amplitude. If the second stage charging time  432  is smaller than the typical charging time, and the fine-tune condition is matched, then the updated high level period=a predetermined high level period−a fine-tune adjustment amplitude. Finally, the processing module uses the reduced adjustment amplitude as the updated adjusting amplitude in the next calibrating loop according to the result of the table lookup analysis procedure  452  and repeats the aforementioned calibrating loop for a predetermined number of times or a termination condition is satisfied. 
     In an embodiment, if the second stage charging time  432  is greater than the typical charging time but the fine-tune condition is not matched, then the updated high level period=a predetermined high level period+a preset adjusting amplitude. If the second stage charging time  432  is smaller than the typical charging time and the fine-tune condition is not matched, the updated high level period=a predetermined high level period−a preset adjusting amplitude. In other words, if the second stage charging time  432  is not matched with the fine-tune condition, and then a coarse adjustment will still be executed in the first calibrating loop. Similarly, the processing module  41  uses the reduced adjustment amplitude as the updated adjusting amplitude for the next calibrating loop, and the aforementioned calibrating loop is repeated until a predetermined number of times or until a termination condition is satisfied. 
     In an embodiment, it is noteworthy to point out that regardless of whether the second stage charging time  432  is matched with the fine-tune condition, the results obtained from the table lookup analysis procedure  452  are used for the calculation when entering into the adjusting process  411  of the second calibrating loop, that the estimated high level period and the reduced adjustment amplitude to accelerating the calibrating process. 
     On the other hand, those ordinarily skilled in the art can combine each functional module into an integrated device, or separate each functional module into finer devices, or use different measures to achieve the same function and the same effect without departing from the spirit and the scope of the present invention. 
     With reference to  FIGS. 5A and 5B  for a flowchart of a charger calibrating device in accordance with the second preferred embodiment of the present invention, the charger calibrating device executes a procedure comprising the following steps: 
     Step S 51 : Execute an initial setup. 
     Step S 52 : Determine whether the number of times of executing a calibrating loop is equal to a predetermined number of times; if yes, then go to Step S 60  and terminate the calibrating process, or else go to Step S 53 . 
     Step S 53 : Execute a first stage charging, a second stage charging and a partial discharge. 
     Step S 54 : Determine whether an error condition or a termination condition occurs; if yes, then go to Step S 60 , or else go to Step S 55 . 
     Step S 55 : Determine whether it is the first time to execute the calibrating loop; if yes, then go to Step S 56 , or else go to Step S 58 . 
     Step S 56 : Execute an accelerated adjusting process. 
     Step S 57 : Determine whether the second charging time falls within a range of typical charging time +/−(5%˜8%); if yes, then go to Step S 571  and decrease the preset adjusting amplitude by half to generate a fine-tune adjustment amplitude and go to Step S 572 , or else go to Step S 572  directly. 
     Step S  572 : Find a corresponding inductance and an estimated high level period according to table lookup, and decrease the adjustment amplitude to 15 clocks, and go to Step S 58 . 
     Step S 58 : Determine whether the second charging time is greater than a typical charging time; if yes, then go to Step S 581 , or else go to Step S 582 . 
     Step S 581 : Calculate an updated high level period, wherein the updated high level period=a predetermined high level period+a fine-tune adjustment amplitude (or a preset adjusting amplitude). 
     Step S 582 : Calculate an updated high level period, wherein the updated high level period=a predetermined high level period−a fine-tune adjustment amplitude (or preset adjusting amplitude). 
     Step S 59 : Calculate an updated adjusting amplitude, wherein the updated adjusting amplitude=the reduced adjustment amplitude (15 clock), and return to Step S 52 . 
     With reference to  FIG. 6  for an example of a table lookup of a preferred embodiment of the present invention, the table lookup can be created by different methods. For example, a manufacturer provides each of all inductors within an error range for every 0.5 uH, and then observes a second stage charging time with the same voltage and the same high level period charging, and finally creates a timetable according to the calculated charging time of inductance of each inductor. For the inductance of each inductors with a difference of inductance of 0.5 uH (which is also smaller than 0.5 uH), an estimated high level period is calibrated, such that the second stage charging time is the closest to a designed typical charging time, and generated the estimated high level period of inductance of each inductors to create an estimated high level period table. Therefore, the high level period of a specific inductance of a inductor most suitable for a transformer can be found quickly without going through the calibrating loop for many times. 
     For example, the inductance of the transformer falls within a range of 10.5 uH˜11.0 uH as shown in the figure of the measurement of the charging time of a transformer with unknown inductance (xx.xuH). If the typical charging time is equal to 850000 us, the table lookup shows that such transformer requires a high level period of 425 to achieve the charging time of approximately 850000 us. 
     With reference to  FIGS. 7A and 7B  for a time comparison flowchart of a calibrating process of a charger calibrating device in accordance with a preferred embodiment of the present invention, the method of this preferred embodiment is called Method 1 and the method of the second preferred embodiment is called Method 2 for the convenience of describing the invention. In Method 1, the second stage charging falls within a range from 100V to 320V. In Method 2, the second stage charging falls within a range from 240V to 270V, and this voltage can be adjusted to improve the calibrating efficiency significantly. 
     With reference to  FIG. 7A , data shown in the figure are experiment results obtained from the same initial conditions such as the same camera model, the same inductance and the same power supply. The second stage charging time is equal to the set typical charging time, and the average second stage charging time is equal to the average measurement of the actual tests. In  FIG. 7B , the predetermined high level period is equal to the updated high level period. In other words, both methods can finish the calibrating process in the first calibrating loop. Results of the figure obviously show that the time spent by Method 2 is only one-third of the time spent by Method 1. Therefore, the second stage charging time of Method 2 can be reduced and a partial discharging method can be adopted to improve the calibrating efficiency significantly. 
     Even though the concept of the charger calibrating method of the present invention has been described in the section of the charger calibrating device of the present invention, a flow chart is provided for the detailed description as follows. 
     With reference to  FIG. 8  for a flow chart of a charger calibrating method of the present invention, the charger calibrating method comprises the following steps: 
     Step S 81 : Use a control module to control a charger to be calibrated to execute a first stage charging and a second stage charging to an electronic device. 
     Step S 82 : Use the control module to control an electronic device to execute a discharging process. 
     Step S 83 : If the second stage charging time is greater than or smaller than a typical charging time, using a processing module to execute an adjusting process to add or subtract a predetermined high level period from a preset adjusting amplitude of a switch in a charging circuit of the charger to be calibrated to generate an updated high level period, and decrease the preset adjusting amplitude by half to generate an updated adjusting amplitude. 
     Step S 84 : Use the processing module to repeat the aforementioned calibrating loop, and terminate the calibrating process when the aforementioned calibrating loop is repeated for a predetermined number of times. 
     The detailed description and implementation of the calibrating method of the charger calibrating device in accordance with the present invention have been described above, and will not be described again. 
     In summary, the charger calibrating device and calibrating method of the present invention no longer needs any additional electronic device in the charging circuit to improve the calibrating efficiency and effect, so as to save the manufacturing cost of the charger. In addition, the charger calibrating device and calibrating method of the present invention can execute the charger calibrating process quickly to reduce the production time of the electronic product effectively and find any defect during the production process of the electronic product quickly to calibrate the charger effectively, so as to improve the production capacity and yield rate of the electronic product significantly. Obviously, the present invention can overcome the shortcomings of the prior art.