Abstract:
A battery charger for charging at least two storage batteries, comprises: a first charging pocket for receiving a first storage battery; a second charging pocket for receiving a second storage battery; a main controller for generating a power supply control signal, charging voltage setting control signal according to the voltage types of the batteries inserted in the first and second charging pockets, and charging current setting control signal according to the current capacities of the batteries; a voltage adjustment circuit for adjusting the charging voltage to the levels respectively fit for the voltage types of the batteries according to the charging voltage setting control signal; a current adjustment circuit for adjusting the charging current to the levels respectively fit for the current capacities of the batteries according to the charging current setting control signal; and a power supply control circuit for supplying or blocking the charging voltages to the batteries according to the power supply control signal.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a battery charger for simultaneously charging multiple storage batteries, and more particularly to an apparatus and method for simultaneously charging the multiple storage batteries loaded in the multiple charging pockets of the apparatus by controlling the charging voltage and current according to the voltage types and current capacities of the batteries. 
     2. Description of the Related Art 
     The conventional battery charger for charging the storage batteries such as a Li-Ion battery used in a mobile phone must be provided with multiple DC power sources in order to simultaneously charge multiple batteries. Referring to FIG. 1, the conventional battery charger includes an input terminal  10  for connecting with a power source of AC 110V to 220V, and a full-wave rectifier  12  consisting of bridge diodes D 91 -D 94  and a capacitor C 2  for full-wave rectifying the AC power from the input terminal  10  to produce a smoothed DC voltage. A Zener diode ZD 1 , resistor R 1  and diode D 2  serve to block a higher voltage exceeding a prescribed voltage. The DC voltage from the full-wave rectifier  12  causes a primary coil L 1  of a transformer  14  to induce a secondary voltage in secondary coils L 2 , L 3  and L 4 . A power switch  16  is switched on/off to control the level of the secondary voltage induced in the secondary coils L 2 , L 3  and L 4  according to a switching control signal. 
     The secondary voltage induced in the secondary coil L 2  is rectified by a first rectifying circuit  18  consisting of a resistor R 3 , diode D 3  and capacitor C 3  to stabilize the DC voltage supplied to the power switch  16 . The secondary voltage induced in the secondary coil L 3  is rectified by a second rectifying circuit  20  consisting of a diode D 31  and capacitor C 31 . The rectified voltage from the second rectifying circuit  20  is smoothed by a smoothing circuit  24  consisting of a choke coil L 31 , capacitor C 32  and resistor R 31 , charging the storage batteries. The secondary voltage induced in the secondary coil L 4  is rectified by a third rectifying circuit  22  consisting of a diode D 21  and capacitor C 21 , supplied to a chopper circuit  26 , which consists of a first regulator U 22 , capacitor C 22 , coil L 21  and diode D 22 , to adjust the rectified voltage of the third rectifying circuit  22  to a prescribed level. 
     A first charging voltage control circuit  40  consists of resistors R 30 , R 71 , capacitor C 26 , transistor Q 24 , and field effect transistor FET Q 23  to supply or block the charging voltage to a first battery loaded in a pocket ‘A’ according to a charging on/off control signal generated by a microprocessor  46 . A second charging voltage control circuit  42  consists of resistors R 44 , R 72 , capacitor C 35 , transistor Q 34 , and field effect transistor FET Q 25  to supply or block the charging voltage to a second battery loaded in a pocket ‘B’ according to a charging on/off control signal generated by the microprocessor  46 . 
     A first charging voltage selection circuit  36  consists of resistors R 27 , R 28 , R 29 , variable resistor VR 1 , diode D 23 , capacitor C 50 , and transistor Q 22 , to set a first charging voltage fit for the voltage type of the battery loaded in the pocket ‘A’ according to a charging voltage selection control signal generated by the microprocessor  46 . A second charging voltage selection circuit  38  consists of resistors R 41 , R 42 , R 47 , variable resistor VR 2 , diode D 32 , and transistor Q 33 , to set a second charging voltage fit for the voltage type of the battery loaded in the pocket ‘B’ according to a charging voltage selection control signal generated by the microprocessor  46 . 
     A first charging current control circuit  32  consists of resistors R 34 , R 36 , R 37 , R 38 , R 88 , R 99 , operational amplifier U 23 A, and transistors Q 31 , Q 88 , Q 99 , to regulate the DC current from the smoothing circuit  24 , and to control the charging current according to first and second current control signals generated by the microprocessor  46  detecting the voltage type of the battery. The microprocessor  46  recognizes the voltage types of the first and second batteries loaded in the respective pockets ‘A’ and ‘B’ by detecting the different resistance values of both batteries across resistors R 62  and R 63  respectively connected between the source voltage VCC and the C/F terminals of both batteries, to generate the first and second charging voltage selection control signals according to the voltage types of the batteries, and the switching control signals for supplying the charging voltages to the pockets ‘A’ and ‘B’. It also generates first, second, third, and fourth current control signals according to the current capacities of the batteries, charging on/off control signal by detecting the value of the voltage corresponding to the current detected from the first charging current control circuit  32 , and display control signal to indicate the charged state of the first and second batteries. 
     A charging current/voltage control circuit  34  consists of resistors R 32 , R 40 , R 69 , R 70 , operational amplifiers U 24 A, U 24 B, transistor Q 37 , capacitors C 39 , C 44 , C 45 , C 46 , C 47 , and photo-coupler PC 1 , to compare the charging voltage set by the second charging voltage selection circuit  38  with a prescribed reference voltage to generate a switching control signal for regulating the charging voltage corresponding to the voltage type of the battery, and a switching control signal for controlling the power switch  16  according to the charging current detected from the first charging current control circuit  32 . A charging voltage control circuit  30  consists of a resistor R 25 , operational amplifier U 26 A, diode D 24 , and capacitor C 24 , to compare the charging voltage selected by the first charging voltage selection circuit  36  with a prescribed reference voltage so as to regulate the charging voltage supplied to the battery. 
     A second charging current control circuit  28  consists of resistors R 20 , R 21 , R 22 , R 23 , R 24 , R 80 , capacitor C 23 , operational amplifier U 23 B, and transistor Q 21  to regulate the DC current from the chopper circuit  26 , and to control the charging current according to the fourth current control signal generated by the microprocessor  46  detecting the current capacity of the battery. 
     First and second LED devices  48  and  50  each consist of a pair of green LED for signaling the battery fully charged and red LED for the battery not fully charged. In addition, simultaneously charging both batteries of the pockets ‘A’ and ‘B’, both red and green LEDs are turned on to indicate that the second charging voltage is lower than the first charging voltage. A first regulator  44  adjusts the rectified voltage of the first rectifying circuit  22  to a predetermined level to generate a source voltage Vcc supplied to the charging apparatus. 
     Such a conventional battery charger requires multiple current sources, and thus, separate chopper circuits and voltage and current control circuits for controlling the current sources, so that its circuit is complicated to increase the size together with the cost. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a battery charger for simultaneously charging multiple storage batteries, which employs a single source voltage to alternately charge the multiple storage batteries at different time intervals alternately predetermined according to their current capacities, thus reducing the size and cost of the battery charger. 
     According to an aspect of the present invention, a battery charger for charging at least two storage batteries, comprises: a first charging pocket for receiving a first storage battery; a second charging pocket for receiving a second storage battery; a main controller for generating a power supply control signal, a charging voltage setting control signal according to the voltage types of the batteries inserted in the first and second charging pockets, and a charging current setting control signal according to the current capacities of the batteries; a voltage adjustment circuit for adjusting the charging voltage to the levels respectively fit for the voltage types of the batteries according to the charging voltage setting control signal; a current adjustment circuit for adjusting the charging current to the levels respectively fit for the current capacities of the batteries according to the charging current setting control signal; and a power supply control circuit for supplying or blocking the charging voltages to the batteries according to the power supply control signal. 
     The present invention will now be described more specifically with reference to the drawings attached only by way of example. 
    
    
     BRIEF DESCRIPTION OF THE ATTACHED DRAWINGS 
     FIGS. 1A and 1B are a circuit diagram for illustrating the structure of a conventional battery charger; 
     FIGS. 2A and 2B are a circuit diagram for illustrating the structure of a battery charger according to an embodiment of the present invention; 
     FIG. 3 is a flow chart for illustrating the process of charging a single storage battery loaded in one of the pockets provided in the inventive battery charger; 
     FIGS. 4A and 4B are a flow chart for illustrating the process of charging multiple storage batteries loaded in the multiple pockets provided in the inventive battery charger; 
     FIGS. 5A and 5B show a flow chart for illustrating the process of charging multiple storage batteries loaded in the multiple pockets provided in the inventive battery charger according to another embodiment; and 
     FIG. 6 illustrates the timing pulses for alternately charging the multiple batteries according to another embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, in which like reference numerals describe similar or identical elements, and with particular reference to FIGS. 2A and 2B, the circuit of the present invention includes an input terminal  10  for connecting with a power source of AC 110V to 220V, and a full-wave rectifier  12  consisting of bridge diodes D 91 -D 94  and a capacitor C 2  for full-wave rectifying the AC power from the input terminal  10  are used to produce a smoothed DC voltage. A Zener diode ZD 1 , resistor R 1  and diode D 2  serve to block a higher voltage exceeding a prescribed voltage. The DC voltage form the full-wave rectifier  12  causes a primary coil L 1  of a transformer  14  to induce a secondary voltage in the secondary coils L 2 , L 3  and L 4 . A power switch  16  is switched on/off to control the level of the secondary voltage induced in secondary coils L 2 , L 3  and L 4  according to a switching control signal. 
     The secondary voltage induced in the secondary coil L 2  is rectified by a first rectifying circuit  18  consisting of a resistor R 3 , diode D 3  and capacitor C 3  to stabilize the DC voltage supplied to the power switch  16 . The secondary voltage induced in the secondary coil L 3  is rectified by a second rectifying circuit  20  consisting of a diode D 31  and capacitor C 31 . The rectified voltage from the second rectifying circuit  20  is smoothed by a smoothing circuit  24  consisting of a choke coil L 31 , capacitor C 32  and resistor R 31 , charging the storage batteries. The secondary voltage induced in the secondary coil L 4  is rectified by a third rectifying circuit  22  consisting of a diode D 21  and capacitor C 21 , supplied to a DC/DC converter  44 . 
     A first charging voltage supply control circuit  40  comprises an FET Q 23  to supply or block the charging voltage to a first battery loaded in pocket ‘B’ in response to a charging on/off control signal generated by the a microprocessor  46 . As an example the Samsung Electronics Co. KS 86P40045 microprocessor can be used. A second charging voltage supply control circuit  42  comprises an FET Q 24  to supply or block the charging voltage to a second battery loaded in pocket ‘A’ in response to a charging on/off control signal generated by the microprocessor  46 . A charging voltage selection circuit  36  consists of resistors R 40 , R 41 , R 42 , R 43 , variable resistor VR 1 , and diode D 32 , to set the first charging voltage in response to a charging voltage selection signal generated by the microprocessor  46  detecting the voltage type of the battery loaded in the pocket ‘A’. A charging current control circuit  32  consists of resistors R 33 , R 34 , R 35 , R 36 , R 54 , R 55 , R 56 , R 57 , operational amplifier U 23 , and transistor Q 31 , to regulate the DC current from the smoothing circuit  24 , and to control the charging current according to first, second, and third current control signal generated by the microprocessor  46  detecting the current capacities of the batteries. 
     The microprocessor  46  detects the voltage types of the first and second batteries loaded in the first and second pockets ‘A’ and ‘B’ based on the values of their internal resistances detected across resistors R 64  and R 65  respectively connected with the C/F terminals of the batteries in order to generate first and second charging voltage selection control signals according to the detected voltage types of the batteries. The microprocessor  46  also generates a switching control signal to supply the charging voltages to the pockets ‘A’ and ‘B’, and first, second, and third current control signals according to the detected current capacities of the batteries, a charging on/off control signal based on the detection of the charged states of the batteries according to the value of the current detected from the charging current control circuit  32 , and a display control signal to indicate the charged states of the first and second batteries. The charging current and voltage control circuit  34  consists of resistors R 32 , R 37 , R 38 , R 39 , operational amplifiers U 32 A, U 32 B, transistor Q 37 , capacitors C 39 , C 44 , C 45 , C 46 , C 47 , and photo-coupler PC 1 , to compare the charging voltage set by the charging voltage selection circuit  36  with a prescribed reference voltage so as to generate a switching control signal for supplying the charging voltage fit for the voltage type of the battery, and a switching control signal according to the amount of the charging current detected from the charging current control circuit  32  to control the power switch  16 . 
     First and second LED devices  48  and  50  each consist of a pair of red and green LEDs to indicate the charged states of the batteries under the control of the microprocessor  46 . The green LED indicates the fully charged state, and the red LED indicates the state under charging. When simultaneously charging both batteries of the pockets ‘A’ and ‘B’, both red and green LEDs are all turned on to indicate the state of the second battery being charged by yellow, thus representing that the second charging voltage is lower than the first charging voltage. The DC/DC converter  44  adjusts the rectified voltage from the third rectifying circuit  22  to a predetermined level supplied as a source voltage Vcc for the charger. 
     Describing the process for charging a single battery inserted in one of the pockets of the charger in connection with FIG. 3, the microprocessor  46  proceeds to step  103  upon detecting a storage battery inserted in the pocket ‘A’ in step  101 . In step  103 , it detects the voltage type and current capacity of the battery cell inserted in the pocket ‘A’ based on the voltage levels inputted through ports ‘J’ and ‘L’. As an example, the voltage type is detected to be 4.1V or 4.2V through the port ‘J’, and, also as an example, the current capacity to be small (400 mA), medium (800 mA), or large (1200 mA) through the port ‘L’. The voltage type of the battery inserted in the pocket ‘A’ is detected based on the divided voltage between the resistor R 64  and the resistance R 90  provided in the battery applied through the port ‘J’ of the microprocessor  46 . 
     If the battery inserted in the pocket ‘A’ is detected not as 4.1V but as 4.2V in step  104 , the microprocessor  46  proceeds to step  105  to generate through port ‘T’ logically low signal for the charging voltage selection signal of the battery of the pocket ‘A’, so that the divided voltage produced by the resistors R 40  and R 41  and variable resistor VR 1  of the charging voltage setting circuit  36  is applied to the inverting input (−) of the comparator U 32 A, used as the voltage for setting the charging voltage fit for the voltage type of the storage battery of the pocket ‘A’. Then, the comparator U 32 A compares the set voltage with a prescribed reference voltage applied to the non-inverting input (+), in order to generate logically low or high signal according as the set voltage is higher or lower than the reference voltage. If the output signal of the comparator U 32 A is low, the transistor Q 37  is turned on so as to cause the light emitting diode PCa of the photo-coupler PC 1  to generate a light ray received by the light-sensitive transistor PCb, which is turned on to control the power switch  16 . On the contrary, if the output signal of the comparator U 32 A is high, the transistor Q 37  is turned off, and so the light emitting diode PCa, so that the light-sensitive transistor PCb is also turned off. This operation of turning on and off is rapidly repeated to maintain the charging voltage as 4.2V. 
     On the other hand, if the microprocessor  46  generates high signal through ports ‘S’ and ‘T’ in step  106 , the divided voltage produced by the resistors R 40  and R 41  and variable resistor VR 1  is applied to the inverting input of the comparator U 32 A used as the voltage for setting the charging voltage of the battery of the pocket ‘A’ to 4.1V. Then, the comparator U 32 A compares the set voltage with the reference voltage applied to the non-inverting input (+), in order to generate logically low or high signal according as the set voltage is higher or lower than the reference voltage. If the output signal of the comparator U 32 A is low, the transistor Q 37  is turned on so as to cause the light emitting diode PCa of the photo-coupler PC 1  to generate a light ray received by the light-sensitive transistor PCb, which is turned on to control the power switch  16 . On the contrary, if the output signal of the comparator U 32 A is high, the transistor Q 37  is turned off, and so the light emitting diode PCa, so that the light-sensitive transistor PCb is also turned off This operation of turning on and off is rapidly repeated to maintain the charging voltage as 4.1V. 
     Thereafter, if the microprocessor  46  detects the current capacity of the battery of the pocket ‘A’ to be small (400 mA) in step  107 , it proceeds to step  108  to generate through port ‘N’ low signal supplied through the resistor R 57  to the inverting input (−) of the comparator U 32 B. The comparator U 32 B generate low or high signal in step  108  according as the voltage applied to the inverting input (−) is higher or lower than the reference voltage applied to the non-inverting input (+). If the output signal of the comparator U 32 B is low, the transistor Q 37  is turned on so as to cause the light emitting diode PCa of the photo-coupler PC 1  to generate a light ray received by the light-sensitive transistor PCb, which is turned on to control the power switch  16 . On the contrary, if the output signal of the comparator U 32 B is high, the transistor Q 37  is turned off, and so the light emitting diode PCa, so that the light-sensitive transistor PCb is also turned off. This operation of turning on and off is rapidly repeated to control the charging voltage. When the smoothing circuit  24  supplies the charging voltage, the current flowing through the resistors R 34  and R 35  is amplified through the operational amplifier U 23 , supplied to the base of the transistor Q 31 , whose output is linearly varied according to the output of the operational amplifier U 23  to result in linear variation of the voltage applied to the port ‘R’ of the microprocessor  46 . Thus, the microprocessor  46  may convert the voltage variation into the value of the current flowing through the resistors R 35  and R 34 . Subsequently, the microprocessor  46  supplies the first charging voltage supply control signal through the port ‘I’ to the gate of the FET Q 24  to charge the battery of the pocket ‘A’. 
     However, if the current capacity of the battery is not detected small in step  107 , the microprocessor  46  proceeds to step  109  to detect it to be medium (800 mA). Then, in step  110 , the microprocessor  46  generates a low signal through the port ‘O’ to the resistor R 56 . In step  113 , the microprocessor  46  supplies the first charging voltage supply control signal through the port ‘I’ to the gate of the FET Q 24  to charge the battery of the pocket ‘A’. On the other hand, if the current capacity of the battery is not detected medium in step  109 , the microprocessor  46  proceeds to step  111  to detect it to be large (1200 mA). Then, in step  112 , the microprocessor  46  generates a low signal through the port ‘P’ to the resistor R 55 . In step  113 , the microprocessor  46  supplies the first charging voltage supply control signal through the port ‘I’ to the gate of the FET Q 24  to charge the battery of the pocket ‘A’. Meanwhile, the microprocessor  46  checks the charging state of the battery of the pocket ‘A’ through the port ‘S’. For example, it periodically detects whether the current flowing from the battery is 120 mA, 90 mA or 70 mA respectively for the large, medium or small current capacity. Detecting the same value  19  times and the fully charged voltage of 3.9V maintained for a predetermined time, the battery inserted in the pocket ‘A’ is determined to be in the fully charged state. The battery being fully charged, the microprocessor  46  applies the first charging voltage cut-off signal to the gate of the FET Q 24  to stop the charging. However, reverting to step  101 , if the battery is not inserted in the pocket ‘A’, it proceeds to step  102  to check the battery to be inserted in the pocket ‘B’. The battery being inserted in the pocket ‘B’, the steps of  103  to  113  are likewise performed to charge the battery. 
     Describing the process for charging the batteries simultaneously inserted in the two pockets in connection with FIG. 4, if a battery is inserted in the pocket ‘A’ and under charging in step  201 , as described with reference to FIG. 3, the microprocessor  46  proceeds to step  202  to check the pocket ‘B’ to have a battery. Not detecting the battery in the pocket ‘B’, the step  203  is carried out to keep on charging of the battery in the pocket ‘A’. On the contrary, a battery being inserted in the pocket ‘B’ in step  202 , the step  204  is performed to detect the voltage type and current capacity of the battery of the pocket ‘B’. In this case, the microprocessor  46  detects the current capacity through the port ‘M’ and the voltage type through the port ‘K’. Then, in step  205 , the microprocessor  46  makes the voltage and current setting according to the voltage type and current capacities of the batteries in both pockets ‘A’ and ‘B’, as shown in the following Table 1. 
     
       
         
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Voltage Setting 
                 Current Selection 
               
             
          
           
               
                   
                   
                 Voltage Selection 
                   
                   
                 Current Selection 
               
               
                 Pocket A 
                 Pocket B 
                 Signal 
                 Pocket A 
                 Pocket B 
                 Signal 
               
               
                   
               
             
          
           
               
                 4.1 V 
                 4.1 V 
                 High Signal through 
                 Small 
                 Small 
                 High Signal 
               
               
                   
                   
                 Ports ‘S’ &amp; ‘T’ 
                   
                   
                 through Port ‘N’ 
               
               
                 4.2 V 
                 4.1 V 
                 Low Signal through 
                 Small 
                 Medium 
                 High Signal 
               
               
                   
                   
                 Port ‘S’ 
                   
                   
                 through Port ‘O’ 
               
               
                 4.1 V 
                 4.2 V 
                 Low Signal through 
                 Medium 
                 Large 
                 High Signal 
               
               
                   
                   
                 Port ‘S’ 
                   
                   
                 through Port ‘P’ 
               
               
                 4.2 V 
                 4.2 V 
                 Low Signal through 
                 Large 
                 Large 
                 High Signal 
               
               
                   
                   
                 Port ‘T’ 
                   
                   
                 through Port ‘V’ 
               
               
                   
               
             
          
         
       
     
     In step  206 , the microprocessor  46  generates high signal through the ports ‘H’ and ‘I’ to turn on the FETs Q 23  and Q 24  to charge the batteries of the pockets ‘A’ and ‘B’. The values of the resistors R 54 , R 55 , R 56 , and R 57  should be determined according to the current capacities of the batteries. 
     However, if the battery of the pocket ‘A’ is not under charging in step  201 , the battery of the pocket ‘B’ is checked to be under charging in step  207 . If the battery of the pocket ‘B’ is under charging, the step  208  is performed to check a battery inserted in the pocket ‘A’. The process goes to step  209  or step  201  depending on whether a battery is inserted in pocket ‘A’ or not. In step  209 , the microprocessor detects the current capacity of the battery in the pocket ‘A’ through the port ‘L’, and its voltage type through the port ‘J’. In step  210 , the microprocessor  46  sets the voltages and currents according to the voltage types and current capacities of the batteries of the pockets ‘A’ and ‘B’, as shown in Table 1, and proceeds to step  211  to generate a high signal through ports ‘H’ and ‘I’ to turn on the FETs Q 23  and Q 24  to charge the batteries of the pockets ‘A’ and ‘B’. 
     Meanwhile, if the microprocessor  46  detects the fully charged state of the battery of pocket ‘B’ in step  212 , it proceed to step  213  to control the second LED device  50  to turn on the green LED indicating the fully charged state. Then, the microprocessor  46  generates a low signal through the port ‘H’ to turn off the FET Q 23  to stop the charging. In addition, the microprocessor  46  detects in step  215  through the ports ‘J’ and ‘L’ whether the battery of pocket ‘A’ is fully charged. If the battery of pocket ‘A’ is not fully charged, it proceeds to step  216  to keep on charging the battery. However, detecting the fully charged state of the battery in pocket ‘A’, the microprocessor  46  proceeds to step  217  to control the first LED device  48  to turn on the green LED indicating the fully charged state. Then, the microprocessor  46  generates in step  218  a low signal through the port ‘I’ to turn off the FET Q 24  to stop the charging. 
     However, if the battery of pocket ‘B’ is not fully charged in step  212 , the microprocessor detects in step  219  through the ports ‘J’ and ‘L’ whether the battery of pocket ‘A’ is fully charged. Not detecting the fully charged state of the battery of pocket ‘A’, step  220  is performed to keep on charging the batteries of pockets ‘A’ and ‘B’. On the contrary, if the battery of pocket ‘A’ is fully charged, the microprocessor  46  proceeds to step  221  to control the first LED device  48  to turn on the green LED indicating the fully charged state. Then, the microprocessor  46  generates in step  222  a low signal through the port ‘I’ to turn off the FET Q 24  to stop the charging. Subsequently, the microprocessor detects in step  223  through the ports ‘M’ and ‘K’ whether the battery of pocket ‘B’ is fully charged. Not detecting the fully charged state of the battery of pocket ‘B’, step  224  is performed to keep on charging the battery of pocket ‘B’. On the contrary, if the battery of pocket ‘B’ is fully charged, the microprocessor  46  proceeds to step  225  to control the second LED device  50  to turn on the green LED indicating the fully charged state. Then, the microprocessor  46  generates in step  226  a low signal through the port ‘H’ to turn off the FET Q 23  to stop the charging. 
     Describing another embodiment of the inventive process for charging the multiple batteries inserted in the multiple pockets of the charger in connection with FIGS. 5A,  5 B and  6 , the microprocessor  46  checks to see if it detects a battery inserted in pocket ‘A’ in step  301 . If no battery is detected in pocket ‘A’ the process proceeds to step  301   a  to check pocket ‘B’. This process continues until a battery is detected in one of the pockets. If a battery is detected in pocket ‘B’ then the process proceeds as depicted in FIGS. 5A and 5B with the labels ‘A’ and ‘B’ substituted for each other. If a battery is detected in pocket ‘A’ the process proceeds to step  302  to detect the voltage type and current capacity of the battery of pocket ‘A’ based on the voltage level inputted through the ports ‘J’ and ‘L’. Namely, through the port ‘J’ is detected whether the voltage type is 4.1V or 4.2V, and through the port ‘L’ whether the current capacity is small (400 mA), medium (800 mA), or large (1200 mA). The voltage type of the battery inserted in pocket ‘A’ is detected based on the divided voltage between the resistor R 64  and the resistance R 90  provided in the battery applied through the port ‘J’ of the microprocessor  46 . 
     If the battery inserted in pocket ‘A’ is detected not as 4.1V but as 4.2V, the microprocessor  46  proceeds to step  304  to generate through port ‘T’ low signal for the charging voltage selection signal of the battery of pocket ‘A’, so that the divided voltage produced by the resistors R 40  and R 41  and variable resistor VR 1  of the charging voltage setting circuit  36  is applied to the inverting input of the comparator U 32 A, used as the voltage for setting the charging voltage fit for the voltage type of the storage battery of the pocket ‘A’. Then, the comparator U 32 A compares the set voltage with a prescribed reference voltage applied to the non-inverting input (+), in order to generate a logically low or high signal depending on whether the set voltage is higher or lower than the reference voltage. If the output signal of the comparator U 32 A is low, the transistor Q 37  is turned on so as to cause the light emitting diode PCa of the photo-coupler PC 1  to generate a light ray received by the light-sensitive transistor PCb, which is turned on to control the power switch  16 . On the contrary, if the output signal of the comparator U 32 A is high, the transistor Q 37  is turned off, and so the light emitting diode PCa, so that the light-sensitive transistor PCb is also turned off, This operation of turning on and off is rapidly repeated to maintain the charging voltage as 4.2V. 
     On the other hand, if the microprocessor  46  generates a high signal through ports ‘S’ and ‘T’ for the voltage type of 4.1V in step  305 , the divided voltage produced by the registers R 40  and R 41  and variable resistor VR 1  is applied to the inverting input of the comparator U 32 A used as the voltage for setting the charging voltage of the battery of pocket ‘A’ to 4.1V. Then, the comparator U 32 A compares the set voltage with the reference voltage applied to the non-inverting input (+), in order to generate a logically low or high signal depending on whether the set voltage is higher or lower than the reference voltage. If the output signal of the comparator U 32 A is low, the transistor Q 37  is turned on so as to cause the light emitting diode PCa of the photo-coupler PC 1  to generate a light ray received by the light-sensitive transistor PCb, which is turned on to control the power switch  16 . On the contrary, if the output signal of the comparator U 32 A is high, the transistor Q 37  is turned off, and so the light emitting diode PCa, so that the light-sensitive transistor PCb is also turned off. This operation of turning on and off is rapidly repeated to maintain the charging voltage as 4.1V. 
     Thereafter, if the microprocessor  46  detects the current capacity of the battery of pocket ‘A’ to be small (400 mA) in step  306 , it proceeds to step  307  to generate through port ‘N’ a low signal supplied through the resistor R 57 . In this case, When the smoothing circuit  24  supplies the charging voltage, the current flowing through the resistors R 34  and R 35  is amplified through the operational amplifier U 23 , supplied to the base of the transistor Q 31 , whose output is linearly varied according to the output of the operational amplifier U 23  to result in linear variation of the voltage applied to the port ‘R’ of the microprocessor  46 . Thus, the microprocessor  46  may convert the voltage variation into the value of the current flowing through the resistors R 35  and R 34 . 
     However, if the current capacity of the battery is not detected small in step  306 , the microprocessor  46  proceeds to step  308  to detect it to be medium (800 mA). Detecting medium, the microprocessor  46  generates in step  309  a low signal through the port ‘O’ to the resistor R 56 . On the other hand, if not detecting medium in step  308 , the microprocessor  46  proceeds to step  310  to check whether the current capacity of the battery is large (1200 mA). If so, the microprocessor  46  generates in step  311  a low signal through the port ‘P’ to the resistor R 55 . Thus, selecting the current and voltage fit for the current capacity and voltage type of the battery of pocket ‘A’, the microprocessor  46  supplies in step  311  the first charging voltage supply control signal through the port ‘I’ to the gate of the FET Q 24  to charge the battery of pocket ‘A’. 
     Meanwhile, the microprocessor  46  detects in step  313  whether a battery is inserted in pocket ‘B’. If not detecting the battery, it returns to step  312 . But, if detecting it, it proceeds to step  314  to generate through port ‘I’ a low signal applied to the gate of the FET  24 , which then is turned off to stop the charging of the battery in pocket ‘A’. In step  315 , the microprocessor  46  detects the voltage type and current capacity of the battery in pocket ‘B’ based on the voltage levels input through the ports ‘K’ and ‘M’. Namely, through the port ‘K’ is detected the voltage type, 4.1V or 4.2V, and through the port ‘M’ the current capacity, 400 mA, 800 mA or 1200 mA. In step  316 , the microprocessor  46  detects the charging state of the battery in pocket ‘A’ based on the voltage level input through the port ‘L’, proceeding to step  317  to set the voltages and currents according to the voltage types and current capacities of the batteries inserted in pockets ‘A’ and ‘B’, as described in Table 1. 
     In step  318 , the microprocessor  46  alternately provide the gates of the FETs Q 23  and Q 24  with charging voltage supplying control signals according to the voltage types and current capacities of the batteries in pockets ‘A’ and ‘B’. Of course, the time intervals for alternately charging the batteries in pockets ‘A’ and ‘B’ are determined according to the voltage types and current capacities. For example, setting the time difference as 1 minute for the charging voltage difference of 0.1V and as 1 minute for the current capacity difference between the two batteries, the microprocessor  46  applies a control signal as shown by B 1  of FIG. 6 to the FET Q 24 , and a control signal as shown by B 2  of FIG. 6 to the FET Q 23 , respectively for the battery with the charging voltage of 2.8V and the small current capacity in the pocket ‘A’ and the battery with the charging voltage of 3.0V and the medium current capacity in the pocket ‘B’. Thus, the batteries in the pockets ‘A’ and ‘B’ are alternately charged respectively for 3 minutes and 6 minutes until fully charged. 
     Thereafter, detecting the fully charged state of the battery in pocket ‘A’, the microprocessor  46  proceeds to step  320  to turn on the green LED of the first LED device  48  indicating the fully charged state as well as to generate low signal through the port ‘I’ to turn off the FET Q 24  stopping the charging. Meanwhile, the microprocessor  46  checks the charged state of the battery in pocket ‘B’ through the ports ‘K’ and ‘M’ in step  322 . If not detecting the fully charged state, it supplies in step  323  the charging voltage supplying control signal to the gate of the FET Q 23  to keep on charging of the battery in pocket ‘B’. However, detecting the fully charged state, it proceeds to step  324  to turn on the green LED of the second LED device  50  indicating the fully charged state of the battery in pocket ‘B’ as well as to generate a low signal through the port ‘H’ to turn off the FET Q 23  stopping the charging of the battery in pocket ‘B’. 
     However, reverting to step  319 , if the battery in pocket ‘A’ is not fully charged, the microprocessor  46  proceeds to step  326  to detect through the ports ‘M’ and ‘K’ whether the battery of the pocket ‘B’ is fully charged. If not detecting the fully charged state of the battery of pocket ‘B’, the process returns to step  318 . Or otherwise, it proceeds to step  327  to turn on the green LED of the second LED device  50  indicating the full charged state of the battery of pocket ‘B’, and generates a low signal through the port ‘H’ to turn off the FET Q 23 , proceeding to step  329  to detect through the ports ‘L’ and ‘J’ whether the battery of the pocket ‘A’ is fully charged. If not detecting the fully charged state of the battery in the pocket ‘A’, it proceeds to step  330  to keep on charging it. However, detecting the fully charged state, it proceeds to step  331  to turn on the green LED of the first LED device  48  indicating the fully charged state of the battery in pocket ‘A’, and generates in step  332  a low signal through the port ‘I’ to turn off the FET Q 24  stopping the charging. Of course, the method of detecting the fully charged state is achieved as shown in FIG.  3 . 
     Thus, the multiple batteries inserted in the multiple pockets of the battery charger may be charged simultaneously by using a single voltage source, thereby reducing its size and cost. 
     While the present invention has been described in connection with specific embodiments accompanied by the attached drawings, it will be readily apparent to those skilled in the art that various changes and modifications may be made thereto without departing the gist of the present invention.