Detecting a microcurrent and a microcurrent detecting circuit
First Claim
1. A battery circuit comprising:
- a capacitor selectively connectable to a secondary battery;
a current amplifier amplifying battery current received from the secondary battery and supplying output current to the capacitor; and
a monitor circuit coupled to the capacitor to detect a characteristic of the secondary battery indirectly by measuring a voltage of the capacitor or by measuring a capacitor discharge current from the capacitor.
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Accused Products
Abstract
Current flows from the secondary battery via the current mirror circuit to the regenerative capacitor. The current mirror circuit multiplies by a numerical constant the current flowing from the secondary battery and supplies the amplified current through the regenerative capacitor. When a voltage value of the regenerative capacitor reaches a predetermined maximum value, the current flows from the regenerative capacitor to the external load. The current flow from the regenerative capacitor continues until the voltage decreases to a predetermined minimum value. Immediately before the voltage of the regenerative capacitor reaches the predetermined minimum value, a terminal voltage of the secondary battery in an open state is measured. This structure enables a charging-and-discharging microcurrent from the secondary battery to be easily monitored, while simultaneously detecting a remaining capacity of the secondary battery.
49 Citations
24 Claims
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1. A battery circuit comprising:
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a capacitor selectively connectable to a secondary battery;
a current amplifier amplifying battery current received from the secondary battery and supplying output current to the capacitor; and
a monitor circuit coupled to the capacitor to detect a characteristic of the secondary battery indirectly by measuring a voltage of the capacitor or by measuring a capacitor discharge current from the capacitor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A battery circuit comprising:
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a secondary battery;
a current amplifier amplifying current from the secondary battery and supplying output current to a capacitor, a current path from the secondary battery to the capacitor selectively connected to charge the capacitor;
a monitor circuit coupled to the capacitor to detect a characteristic of the secondary battery indirectly by measuring a voltage of the capacitor with the capacitor disconnected from the secondary battery. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of measuring a microcurrent flowing from a secondary battery in a battery circuit, the method comprising:
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turning a first switch ON to connect the secondary battery to a capacitor in common with gate terminals of first and second transistors constituting a current amplifier and turning a second switch OFF to disconnect drain terminals of the first and second transistors, monitoring a terminal voltage of the capacitor with a capacitor voltage monitor to identify when the terminal voltage of the capacitor increases to a predetermined maximum voltage;
turning the first switch OFF and the second switch ON to connect the capacitor and an external load when the terminal voltage of the capacitor reaches the predetermined maximum voltage;
monitoring the terminal voltage of the capacitor with the capacitor voltage monitor to identify when the terminal voltage of the capacitor decreases to a predetermined minimum voltage; and
turning the first switch ON and turning the second switch OFF to repeat the same cycle. - View Dependent Claims (21, 22, 23, 24)
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Specification