Electricity: battery or capacitor charging or discharging – Battery or cell discharging – With charging
Reexamination Certificate
2002-06-14
2003-10-28
Tso, Edward H. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell discharging
With charging
C320S136000
Reexamination Certificate
active
06639387
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a battery pack which includes a battery, and a battery protection circuit for protecting the battery from overcharge and overdischarge, and has a reduced number of inspection terminal for inspecting the operation of the battery protection circuit. The invention also relates to an inspection device for a battery pack for inspecting the operation of the battery protection circuit.
BACKGROUND ART
A battery pack using a rechargeable battery having a high energy density such as a lithium ion rechargeable battery is provided with a battery protection circuit for protecting the rechargeable battery from overcharge and overdischarge.
FIG. 3
shows a constitution of a battery pack
20
provided with a battery protection circuit
21
, and a device for inspecting the operation of the battery protection circuit
21
.
As shown in
FIG. 3
, the battery pack
20
includes a rechargeable battery
28
, and the battery protection circuit
21
. A control circuit
29
constituting this battery protection circuit
21
monitors the voltage of the rechargeable battery
28
. The circuit
29
controls to set a first FET
26
serially connected with an input/output circuit of the rechargeable battery
28
to a cutoff state when a voltage in an overcharged state is detected, and stops charging the rechargeable battery
28
. The control circuit
29
controls to set a second FET
27
serially connected with the input/output circuit of the rechargeable battery
28
to a cutoff state when a voltage in an overdischarged state is detected, and stops discharging the rechargeable battery
28
. This operation of the control circuit
29
protects the rechargeable battery
28
from overcharge and overdischarge.
The battery pack
20
is provided with inspection terminals
24
and
25
which are connected with the control circuit
29
, and are used for inspecting the operation of the battery protection circuit
21
in addition to a positive electrode input/output terminal
22
and a negative electrode input/output terminal
23
.
When an overcharge protection operation is inspected, a charging power supply
30
and an ammeter
31
are connected between the positive electrode input/output terminal
22
and the negative electrode input/output terminal
23
, and a constant voltage power supply
32
is connected with the inspection terminals
24
and
25
as shown in FIG.
3
. The charging power supply
30
supplies a charging power for setting the battery pack
20
to a charging state, and the constant voltage power supply
32
impresses an overcharge inspection voltage, which sets the rechargeable battery
28
to an overcharged state, between the inspection terminals
24
and
25
. The control circuit
29
detects this overcharge inspection voltage, and controls the first FET
26
to cut off the input/output circuit, and the ammeter
31
detects the cutoff of the input/output circuit. Thus, it is determined whether the overcharge protection operation of the battery protection circuit
21
is normal or not based on whether the read of the ammeter
31
is zero or not when the overcharge inspection voltage is impressed by the constant voltage power supply
32
.
When an overdischarge protection operation is inspected, a discharging load
33
and the ammeter
31
are connected between the positive electrode input/output terminal
22
and the negative electrode input/output terminal
23
, and the constant voltage power supply
32
is connected with the inspection terminals
24
and
25
. Connecting the discharging load
33
sets the battery pack
20
to a discharging state, and the constant voltage power supply
32
impresses an overdischarge inspection voltage, which sets the rechargeable battery
28
to an overdischarged state, between the inspection terminals
24
and
25
. The control circuit
29
detects this overdischarge inspection voltage, and controls the second FET
27
to cut off the input/output circuit, and the ammeter
31
detects the cutoff of the input/output circuit. Thus, it is determined whether the overdischarge protection operation of the battery protection circuit
21
is normal or not based on whether the read of the ammeter
31
is zero or not when the overdischarge inspection voltage is impressed by the constant voltage power supply
32
.
However, since the battery pack
20
having the conventional constitution requires the two inspection terminals
24
and
25
for inspecting the battery protection circuit
21
, there is such a problem as the area of a circuit board and the volume of a pack case increase. As the size and the thickness of portable devices on which the battery pack
20
is mounted reduce, reducing the size and the thickness of the battery pack
20
becomes necessary, and reducing the space for providing the inspection terminals
24
and
25
becomes desired.
Since wiring connected with the individual inspection terminals
24
and
25
may receive electromagnetic radiation from outside, or may generate unnecessary electromagnetic radiation to outside, the wiring may influence a device on which the battery pack
20
is mounted, or may cause a malfunction of the battery protection circuit
21
.
An object of the present invention is to provide a battery pack using one inspection terminal to inspect the operation of the battery protection circuit, and an inspection device for the inspection.
DISCLOSURE OF THE INVENTION
A first aspect of the present invention is a battery pack which includes a rechargeable battery, a positive electrode input/output terminal connected with a positive electrode of the rechargeable battery, a negative electrode input/output terminal connected with a negative electrode of the battery, switching elements serially connected with an input/output circuit extending from the rechargeable battery to the positive electrode input/output terminal and the negative electrode input/output terminal, and a control circuit for monitoring a voltage between the positive and negative electrodes of the rechargeable battery, and setting the switching element to a cutoff state when an overcharge voltage in an overcharged state, or an overdischarge voltage in an overdischarged state is detected. The battery pack further includes an inspection terminal for outward extending a positive electrode voltage input terminal of the control circuit used for receiving the positive electrode voltage of the rechargeable battery, and a part between the inspection terminal and the negative electrode input/output terminal is constituted as an input unit for an inspection voltage for inspecting an overcharge protection operation and an overdischarge protection operation by the control circuit.
A second aspect of the invention is an inspection device for a battery pack which includes a rechargeable battery, a positive electrode input/output terminal connected with a positive electrode of the rechargeable battery, a negative electrode input/output terminal connected with a negative electrode of the battery, switching elements serially connected with an input/output circuit extending from the rechargeable battery to the positive electrode input/output terminal and the negative electrode input/output terminal, a control circuit for monitoring a voltage between the positive and negative electrodes of the rechargeable battery, and setting the switching element to a cutoff state when an overcharge voltage in an overcharged state, or an overdischarge voltage in an overdischarged state is detected, and an inspection terminal for outward extending a positive electrode voltage input terminal of the control circuit used for receiving the positive electrode voltage of the rechargeable battery. The inspection device detects an overcharge protection operation or an overdischarge protection operation of the battery pack by current detection means installed in a charging circuit or a discharging circuit while a charging power supply or a discharging load is connected between the positive electrode input/output terminal and the negative electrode input/output terminal
Kitagawa Katsunori
Nagahisa Tetsuo
Jordan and Hamburg LLP
Matsushita Electric - Industrial Co., Ltd.
Tso Edward H.
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