Abstract:
A battery charger is disclosed to includes a power supply unit for converting AC power supply into DC power supply, and a charging unit, which is detachably connected to the power supply unit and adjustable through a rotary knob to change the length of the battery chambers thereof to fit different sizes of battery cells to be charged by the charging unit.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to battery chargers and more particularly, to such a battery charger that is adjustable to fit different sizes of battery cells. 
         [0003]    2. Description of the Related Art 
         [0004]    A conventional battery charger comprises a power circuit unit for converting AC power supply into DC power supply, and a charging circuit unit for charging inserted battery with output DC power supply from the power circuit unit. This design of battery charger does not provide any added function. Further, this design of battery charger can only charge a specific size of battery cells. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention has been accomplished under the circumstances in view. It is therefore the main object of the present invention to provide a battery charger, which is adjustable to fit different sizes of battery cells. It is another object of the present invention to provide a battery charger, which provides an added illumination function. According to one aspect of the present invention, the battery charger comprises a power supply unit for converting AC power supply into DC power supply, and a charging unit, which is detachably connected to the power supply unit and adjustable through a rotary knob to change the length of the battery chambers thereof to fit different sizes of battery cells to be charged by the charging unit. According to another aspect of the present invention, the power supply unit has a plurality of light emitting diodes for giving off light for illumination, and a lens through which the light of the light emitting diodes passes to the outside for illumination. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is an exploded view of a battery charger according to the present invention. 
           [0007]      FIG. 2  shows the power supply unit and the charging unit respectively assembled before insertion of the charging unit into the top accommodation open chamber of the power supply unit according to the present invention. 
           [0008]      FIG. 3  corresponds to  FIG. 2 , showing the charging unit inserted into the top accommodation open chamber of the power supply unit. 
           [0009]      FIG. 4  is a side view in section of the battery charger according to the present invention. 
           [0010]      FIG. 5  is similar to  FIG. 4  but showing the pitch between the metal contact members of the locating plate and the metal contact members of the slide adjusted. 
           [0011]      FIG. 6  is a circuit diagram of the circuit board of the charging unit. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0012]    Referring to  FIGS. 1˜5 , a battery charger in accordance with the present invention is shown comprised of a power supply unit  100 , and a charging unit  200 . 
         [0013]    The power supply unit  100  comprises a casing  10 , a circuit board  14  mounted inside the casing  10 , and a cover shell  11  covering the casing  10 . The circuit board  14  has metal blades  15  extending out of the casing  10  for insertion into an AC outlet to receive city power supply for conversion into DC power supply by the circuit board  14 , an electric output connector  16  for DC output, a switch  17  for switching on/off the electric output connector  16 , and a plurality of LEDs (light emitting diodes)  18 . The cover shell  11  has a lens  13  through which the light of the LEDs  18  pass to the outside of the power supply unit  100  for illumination, and a top accommodation open chamber  12  adapted to accommodate the charging unit  200 . 
         [0014]    The charging unit  200  comprises a battery holder  20 , which has a plurality of battery chambers  21  for holding battery cells V and a sliding hole  22  axially disposed in one end, a locating plate  30 , which is fastened to one end of the battery holder  20  opposite to the sliding hole  22  and has a plurality of metal contact members  31  respectively disposed in contact with one terminal of each battery cell V installed in the battery chambers  21 , a circuit board  32 , which is mounted on the locating plate  30  and has an electric output connector  33  for DC output and a selector switch  34  for switching on/off the electric output connector  33  between a first position to provide power supply to an external electric apparatus and a second position to charge the battery cells V; when switching on the electric output connector  33 , the charging unit  200  works to provide power supply to an external electric apparatus), a cap  35  capped on one end of the battery holder  20  and covered over the locating plate  30  and the circuit board  32 , a spring member  23  mounted inside the sliding hole  22  of the battery holder  20 , a slide  24  axially slidably coupled to the battery holder  20 , an actuating member  27 , a cover shell  28 , and a rotary knob  29 . The slide  24  has a plurality of metal contact members  25  for contacting the other terminal of each battery cell V installed in the battery chambers  21 , a projecting guide bar  26 , which has a beveled guide face  260 , and a coupling rod  240  and slidably inserted into the sliding hole  22  of the battery holder  20  and stopped against the spring member  23 . The cover shell  28  is capped on one end of the battery holder  20  opposite to the cap  35  to hold the actuating member  27  in place. The actuating member  27  is inserted through the cover shell  28  and affixed to the rotary knob  29 , having two beveled guide faces  270  selectively disposed in contact with the beveled guide face  260  of the projecting guide bar  26 . When rotating the rotary knob  29 , the actuating member  27  is rotated with the rotary knob  29  to move the associating beveled guide face  270  against the beveled guide face  260  of the projecting guide bar  26 , thereby adjusting the pitch between the metal contact members  31  of the locating plate  30  and the metal contact members  25  of the slide  24  subject to the size (length) of the battery cells V that are installed in the battery chambers  21 . 
         [0015]    When the charging unit  200  is inserted into the top accommodation open chamber  12  of the cover shell  11  of the power supply unit  100 , the circuit board  32  is electrically connected to the electric output connector  16  of the circuit board  14 . 
         [0016]    Referring to  FIG. 6 , the circuit board  32  of the charging unit  200  comprises a voltage dropping circuit  1 , adapted to drop the voltage of the output power supply of the power supply unit  100  into a predetermined charging voltage for charging the battery cells V that are mounted in the battery chambers  21  of the battery holder  20 , a protection circuit  2  comprised of a transistor Q 2  and electrically connected to the output end of the voltage dropping circuit  1  for cutting off the circuit when the voltage passing out of the voltage dropping circuit  1  into the protection circuit  2  is abnormal (surpassed a predetermined voltage level), a booster circuit  3  electrically connected to the output end of the protection circuit  2  to boost the voltage of output power outputted from the protection circuit  2  for supply to an external electric apparatus through the electric output connector  33  of the circuit board  30  of the charging unit  200  when the switch  34  is switched to the first position (switched on the electric output connector  33 ), and a charging indicator circuit  4  comprised of a transistor Q 3  and a LED D. During a charging operation of the battery charger, the transistor Q 3  is electrically connected to turn on the LED D, giving a signal indicative of the charging operation. 
         [0017]    Referring to  FIGS. 3 and 4  again, when the switch  34  is switched to the second position (switched off the electric output connector  33 ) after connection of the metal blades  15  to an electric outlet, the circuit board  14  of the power supply unit  100  converts AC power supply into DC power supply for the circuit board  32  of the charging unit  200  to charge the battery cells V that are inserted into the battery chambers  21  of the battery holder  20 . 
         [0018]    Referring to  FIGS. 4 and 5  again, the user can rotate the rotary knob  29  to force the actuating member  27  to move the slide  24 , thereby adjusting the pitch between the metal contact members  31  of the locating plate  30  and the metal contact members  25  of the slide  24  subject to the size (length) of the battery cells V that are installed in the battery chambers  21 . 
         [0019]    A prototype of battery charger has been constructed with the features of  FIGS. 1˜6 . The battery charger functions smoothly to provide all of the features discussed earlier. 
         [0020]    Although a particular embodiment of the inventions has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.