Electricity: battery or capacitor charging or discharging – Cell or battery charger structure
Reexamination Certificate
2002-10-22
2004-11-23
Tso, Edward H. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Cell or battery charger structure
Reexamination Certificate
active
06822420
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a rechargeable battery storing a power generating element in an outer case made of a laminated sheet, and having positive and negative electrodes extended as a metallic foil lead. The invention also relates to a battery power source device such as a battery pack including such a rechargeable battery and a circuit board having a battery protection circuit or the like.
BACKGROUND ART
More lightweight, compact and thinner mobile information equipment and audio equipment such as a mobile phone and a mobile computer are in demand so that they can more comfortably be carried around. It should be no exaggeration to say that battery power source devices such as a battery pack hold the key to these improvements. There are demands in particular for more lightweight and thinner power source devices using rechargeable batteries.
Consequently, rechargeable batteries must be reduced in weight and thickness, and there are commercially available rechargeable batteries having a power generating element enclosed in a packaging material of a laminated sheet made by coating both sides of a metal layer with a resin layer. Such a rechargeable battery is surely more lightweight and thinner than the conventional rechargeable battery with a metallic case, while it has less mechanical strength or less heat resistance. Since the positive and negative electrodes are extended as a metallic foil lead, the rechargeable batteries must be handled with considerable care particularly when they are connected in parallel to obtain large battery capacity or when they are connected in series to obtain high voltage. A battery power source device using rechargeable batteries, especially lithium-based rechargeable batteries must have a battery protection device to protect the rechargeable batteries from being overcharged/overdischarged, and therefore how to connect the rechargeable batteries and the battery protection device must be considered as well.
FIG. 35
is a view of a conventional battery pack including a parallel-connection of three lithium polymer rechargeable batteries
401
having an outer case of a laminated sheet, and the batteries are connected to a circuit board
415
having a battery protection circuit. The battery pack is stored in a pack case to complete the battery pack.
As described above, the positive and negative electrodes of the rechargeable battery
401
are both formed as a metallic foil lead having a thickness of at most 0.1 mm. For example, the positive electrode lead
411
is of aluminum and the negative electrode lead
412
is of copper. It is difficult to wire the leads or connect them with a wiring lead. Consequently, in the conventional arrangement, a positive electrode metal plate
416
and a negative electrode metal plate
417
are provided on the sides of an insulating material
418
, and the positive electrode leads
411
of the rechargeable batteries
401
are connected to the positive electrode metal plate
416
, while the negative electrode leads
412
are connected to the negative electrode metal plate
417
. The positive and negative electrode metal-plates
416
and
417
are connected to the circuit board
415
having the battery protection circuit, so that the rechargeable batteries
401
are connected in parallel and power is input/output through the battery protection circuit.
In this arrangement, however, the positive and negative electrode leads
411
and
412
extended from the rechargeable batteries
401
cannot be connected on the same plane, therefore the workability is low and the positive and negative electrode leads
411
and
412
could be damaged during the working. The connection of the positive electrode leads
411
to the positive electrode metal plate
416
and the connection of the negative electrode leads
412
to the negative electrode metal plate
417
are in the front-back relation, the positive electrode leads
411
and the negative electrode leads
412
could be in contact with the negative electrode metal plate
417
and the positive electrode metal plate
416
, respectively. Thus, the insulation between the positive electrodes and the negative electrodes must be enhanced. Moreover, when the metal plates
416
and
417
for the positive and negative electrodes are contacted with the rechargeable batteries
401
because of impact or vibration, the outer case made of a laminated sheet could be damaged. Thus, the rechargeable batteries
401
and the positive and negative electrode metal plates
416
and
417
must be secured. For the purpose, an insulating member or a securing member must be provided at the pack case, which increases the number of necessary members and the number of steps.
What is worse, when a battery power source device includes rechargeable batteries having an outer case made of a soft laminated sheet and is subjected to impact or vibration, the rechargeable batteries could be moved by the weight of the power generating element, which could break off or bend the foil lead extended to the outside from the outer case or the outer case could be damaged. It is therefore a common practice to secure the rechargeable battery to the inner surface of the pack case with a double-faced adhesive tape. Meanwhile, in the rechargeable battery using the soft laminated sheet for the outer case, the strength of securing the power generating element by the outer case is lower than a rechargeable battery storing a power generating element in a metallic case. Thus, if the outer case does not move, the power generating element stored inside could move, which could cause the leads extended from the positive and negative electrode plates to break off or bend in the outer case. The double-faced adhesive tape used to secure the rechargeable battery at the mounting position often damages or scars the outer case when a lining sheet is removed from the tape, and the appearance or reliability of the rechargeable battery could be degraded. In addition, the work of removing the lining sheet lowers the workability.
When the electrode plate is expanded because of repeated charge/discharge or changes with time, the rechargeable battery becomes thicker because the outer case is made of a soft material. As a result, the pack case storing the rechargeable battery could deform or the device provided with the battery pack could adversely be affected.
When the positive and negative electrode leads of a rechargeable battery are connected with a circuit board, the aluminum of the positive electrode lead in particular cannot be soldered to a soldering land on the circuit board. Thus, a plate member of nickel for example is joined to the tip ends of the positive and negative electrode leads by ultrasonic joining, and the plate member is joined to the soldering land on the circuit board by soldering. This method however requires a step of joining the plate member to the positive and negative electrode leads of the rechargeable battery, which increases the number of steps. When a rechargeable battery is handled as a plate member is joined to the tip ends of the positive and negative electrode leads that are made of a low strength foil, an increased weight upon the tip ends tends to cause damages such as breaks and bends to the positive and negative electrode leads.
The soft outer body tends to be scarred or deformed. When a battery power source device is constituted with a plurality of rechargeable batteries, the rechargeable batteries and a circuit board having a battery protection circuit and the like must be integrated, and the elements therefor must be stored in a pack case, which impedes further reduction in the thickness and weight of the battery power source device. In addition, the positive and negative electrode leads are made of a metal foil, and therefore the leads could be disconnected by vibration in ultrasonic welding to join them to the circuit board.
When the rechargeable batteries are combined with a circuit board and formed into a battery pack, the added thickness of the circuit board reduces the advantage that
Aoki Shigeo
Fujiwara Junji
Koyanagi Yoshinori
Kozu Katsumi
Masui Motohide
Jordan and Hamburg LLP
Tso Edward H.
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