Patent ID: 7583057

Claim:
A voltage detection circuit that detects a voltage between both polarities of each storage circuit of a plurality of storage circuits (B 1 , B 2 , B 3 ) connected to one another in series, comprising: a plurality of first capacitors ( 67 , 68 , 69 ); a plurality of first switches ( 62 , 64 , 66 ) each having one end connected to one electrode of said each storage circuit (B 1 , B 2 , B 3 ) and the other end connected to one electrode of said each first capacitor ( 67 , 68 , 69 ); a charging switch ( 71 ) having one end connected in common to the other electrodes of said plurality of first capacitors ( 67 , 68 , 69 ) and the other end connected to a node that sets a reference electric potential; a second capacitor ( 72 ) having one electrode connected to the other end of said charging switch ( 71 ); a plurality of second switches ( 61 , 63 , 65 ) each having one end connected to the other electrode of said each storage circuit (B 1 , B 2 , B 3 ) and the other end connected to said one electrode of said each first capacitor ( 67 , 68 , 69 ); a voltage applying switch ( 70 ) having one end connected in common to said other electrodes of said plurality of first capacitors ( 67 , 68 , 69 ) and the other end connected to the other electrode of said second capacitor ( 72 ); a pair of measuring terminals connected to both ends of said second capacitor ( 72 ); and a control section ( 39 ) that controls said plurality of first switches ( 62 , 64 , 66 ), said charging switch ( 71 ), said plurality of second switches ( 61 , 63 , 65 ) and said voltage applying switch ( 70 ), and show a voltage between both polarities of said selected storage circuit (B 1 , B 2 , B 3 ) for detection to said pair of measuring terminals as output, wherein the control section ( 39 ) selects one storage circuit (B 1 , B 2 , B 3 ) from said plurality of storage circuits (B 1 , B 2 , B 3 ), turn on said first switch ( 62 , 64 , 66 ) having one end connected to said selected storage circuit (B 1 , B 2 , B 3 ) and said charging switch ( 71 ) to charge said first capacitor ( 67 , 68 , 69 ) with the voltage of one electrode of said selected storage circuit (B 1 , B 2 , B 3 ), and turn off said plurality of first switches ( 62 , 64 , 66 ) and said charging switch ( 71 ), and turn on said second switch ( 61 , 63 , 65 ) and said voltage applying switch ( 70 ) to make said first capacitor ( 67 , 68 , 69 ) and said second capacitor ( 72 ) connected in series and apply the voltage of the other electrode of said selected storage circuit (B 1 , B 2 , B 3 ) to said first capacitor ( 67 , 68 , 69 ) and said second capacitor ( 72 ), and make the voltage applied to said second capacitor ( 72 ) outputted at said pair of measuring terminals as the voltage between both polarities of said selected storage circuit.