Electricity: battery or capacitor charging or discharging – Battery or cell charging – Pulsed
Reexamination Certificate
2001-01-09
2001-11-06
Tso, Edward H. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell charging
Pulsed
Reexamination Certificate
active
06313612
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to electronic units, electronic units to be charged, and control methods for electronic units. More particularly, the present invention relates to an electronic unit which charges a portable electronic unit, an electronic unit to be charged which is a portable electronic unit to be charged, and a control method for an electronic unit which charges a portable electronic unit.
2. Background Art
Compact, portable electronic units (electronic units to be charged), such as portable communication terminals and electronic timepieces, which are placed in a charging unit called a station and charged have recently become known. Some compact, portable electronic units which can be charged have lithium-ion secondary batteries as accumulators for accumulating electric energy. Since lithium-ion secondary batteries have advantages of a high energy density and relatively low self-discharging, they are widely used especially for compact, portable electronic units which require a high energy density such as portable telephones, camcorders, and notebook personal computers.
If a voltage equal to or higher than a so-called limit voltage is applied to a lithium-ion secondary battery, dendrite (treelike crystal) is formed, an internal short-circuit occurs, and the life of the battery is reduced. Therefore, in a general charging method, constant-current charging is applied to a lithium-ion secondary battery until the charged voltage (voltage to which the battery is charged) reaches the limit voltage, and then constant-voltage charging is applied after the charged voltage reaches the limit voltage. Details of this charging method are described, for example, in Japanese Unexamined Patent Application Publication No. Hei-5-111184.
In this charging method, however, after the charged voltage reaches the limit voltage, although the consumed current hardly changes, since the charging current is drastically reduced, wasteful power consumption occurs. Since the temperature of the battery continues to rise due to a leakage current and due to the heat of the compact, portable electronic unit caused by the operation of a charging control circuit, the compact, portable electronic unit and the lithium-ion secondary battery may deteriorate.
DISCLOSURE OF THE INVENTION
Accordingly, it is an object of the present invention to provide an electronic unit, an electronic unit to be charged, and a control method for an electronic unit which reduce wasteful current consumed during charging.
According to one mode of the present invention, an electronic unit for charging a unit to be charged having an accumulator section which can be repeatedly charged may include a charging section for charging the accumulator section according to a charging control signal; and with a first effective charging time T
1
serving as an effective charging time per unit time used when charging is achieved if the accumulated voltage of the accumulator section is lower than a reference voltage specified in advance and a second effective charging time T
2
serving as an effective charging time per unit time used when charging is achieved if the accumulated voltage is equal to or higher than the reference voltage, which are specified in advance so as to satisfy an expression (1), a charging control section for outputting the charging control signal according to the first effective charging time T
1
, the second effective charging time T
2
, and the comparison result of the accumulated voltage of the accumulator section and the reference voltage.
T
1
>T
2
(1)
According to another mode of the present invention, an electronic unit for charging a unit to be charged having an accumulator section which can be repeatedly charged may include a charging section for applying pulse charging to the accumulator section according to a charging control signal; and with a first pulse count P
1
used in the pulse charging per unit time in charging achieved if the accumulated voltage is lower than a reference voltage specified in advance and a second pulse count P
2
used in the pulse charging per unit time in charging achieved if the accumulated voltage is equal to or higher than the reference voltage, which are specified in advance so as to satisfy an expression (2), a charging control section or outputting the charging control signal according to the first pulse count P
1
, the second pulse count P
2
, and the comparison result of the accumulated voltage of the accumulator section and the reference voltage.
P
1
>P
2
(2)
According to another mode of the present invention, an electronic unit for charging a unit to be charged having an accumulator section which can be repeatedly charged may include a charging section for charging the accumulator section according to a charging control signal; and with a first effective charging time T
1
serving as an effective charging time per unit time used when charging is achieved if the charging current of the accumulator section is equal to or higher than a reference current specified in advance and a second effective charging time T
2
serving as an effective charging time per unit time used when charging is achieved if the accumulation current is lower than the reference current, which are specified in advance so as to satisfy an expression (1), a charging control section for outputting the charging control signal according to the first effective charging time T
1
, the second effective charging time T
2
, and the comparison result of the accumulation current of the accumulator section and the reference current.
T
1
>T
2
(1)
According to another mode of the present invention, an electronic unit for charging a unit to be charged having an accumulator section which can be repeatedly charged may include a charging section for applying pulse charging to the accumulator section according to a charging control signal; and with a first pulse count P
1
per unit time in charging achieved if the charging current of the accumulator section is equal to or higher than a reference current specified in advance and a second pulse count P
2
per unit time in charging achieved if the accumulation current is lower than the reference current, which are specified in advance so as to satisfy an expression (2), a charging control section for outputting the charging control signal according to the first pulse count P
1
, the second pulse count P
2
, and the comparison result of the accumulation current of the accumulator section and the reference current.
P
1
>P
2
(2)
According to another mode of the present invention, an electronic unit to be charged which is charged by any of the foregoing electronic units may include an accumulator section which can be repeatedly charged; and an accumulated-voltage detecting and outputting section for detecting the accumulated voltage of the accumulator section and for outputting an accumulated-voltage detection result.
According to another mode of the present invention, an electronic unit to be charged which is charged by any of the foregoing electronic units may include an accumulator section which can be repeatedly charged; an accumulated-voltage detecting section for detecting the accumulated voltage of the accumulator section; and a comparison-result outputting section for comparing the accumulated voltage detected by the accumulated-voltage detecting section with a reference voltage specified in advance and for outputting the result of comparison.
According to another viewpoint of the present invention, a control method for an electronic device for charging an apparatus to be charged having an accumulator unit which can be repeatedly charged may include the steps of charging the accumulator unit; and with a first effective charging time T
1
serving as an effective charging time per unit time used when charging is achieved if the accumulated voltage of the accumulator unit is lower than a reference voltage specified in advance and a second effective charging time T
2
se
Hayakawa Motomu
Honda Katsuyuki
Kosuda Tsukasa
Seiko Epson Corporation
Tso Edward H.
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