Patent ID: 7272018

Claim:
A power supply device characterized by comprising: a charging section ( 20 , 50 ) which is activated to charge a charging element ( 24 , 54 ); a direct-current voltage generation section ( 30 , 60 ) which generates a second direct-current voltage based on a first direct-current voltage of said charging element ( 24 , 54 ), and applies the generated second direct-current voltage to a load (L); and an operation control section ( 40 , 41 , 42 , 70 , 71 , 72 , 80 , 90 , 100 ) which actuates said charging section ( 20 , 50 ), determines whether a state of said load (L) to which said direct-current voltage generation section ( 30 , 60 ) applies the second direct-current voltage is a lightly loaded state or not, and in a case where determining that said load (L) enters a lightly loaded state, starts detection of elapsed time, and controls said charging section ( 20 , 50 ) to stop operation of charging said charging element ( 24 , 54 ) when detecting a preset time period elapses after it determines that said load (L) enters the lightly loaded state.