Chemistry: electrical current producing apparatus – product – and – With nonbattery electrical component electrically connected...
Reexamination Certificate
2000-11-30
2003-02-25
Ryan, Patrick (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
With nonbattery electrical component electrically connected...
C429S122000, C429S129000, C429S096000, C429S100000
Reexamination Certificate
active
06524732
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a rechargeable battery, such as a lithium ion rechargeable battery, particularly of a flat shape, which is integrated with a battery protection circuit so that the rechargeable battery itself has a function of protecting against overcharging, overdischarging, and so forth.
BACKGROUND ART
Rechargeable batteries are provided with a variety of protective functions for preventing damage to the battery caused by abnormal use such as overcharging, overdischarging, short-circuiting between the positive and negative electrodes, or short-circuiting of the battery peripheral circuitry of the device in which the battery is used. Examples of these functions include PTC (Positive Temperature Coefficient) elements that prevent excessive discharge current due to short-circuiting or the like, and safety vents that release internal pressure by cutting off the power circuit in the event of an abnormal rise in internal pressure caused by overcharging. These protective functions are known as functions incorporated into the rechargeable battery itself. A lithium ion rechargeable battery is normally provided with a battery protection circuit to prevent overcharging, overdischarging, and so forth. Such battery protection circuit is generally unitized with the battery as part of battery pack configuration, in which a circuit board that makes up the battery protection circuit is integrally contained in the pack case along with the lithium ion rechargeable battery. It is common knowledge that battery packs such as this, in which the rechargeable battery and the protection circuit are integrally housed in a case, are often used for battery-powered devices such as cellular telephones and laptop computers.
In addition to preventing overcharging and overdischarging as mentioned above, this battery protection circuit can also have such functions as cutting off excessive current or monitoring cell temperature, and if this circuit could be integrated with the rechargeable battery itself, it would be possible to create a rechargeable battery equipped with a battery protection circuit without constituting a battery pack, which would make the rechargeable battery more universally applicable.
When a battery protection circuit is integrated with a rechargeable battery, however, it is difficult to avoid making the external dimensions larger or losing the original configuration of the rechargeable battery. In particular, a flat-shaped rechargeable battery is made thin so that it can be used in small devices such as portable devices, and when a battery protection circuit is integrated with such a rechargeable battery it is difficult to find space for the circuit board that makes up the battery protection circuit, which means that it is difficult to integrate a battery protection circuit without increasing the external dimensions.
Also, with a small, flat-shaped rechargeable battery, there is little space in which to provide the above-mentioned PTC element or current cut-off vent, so the elements for electromotive force must be reduced in size in order to ensure this space, the problem with which is that the battery capacity is diminished. Therefore a PTC element must be provided as part of the battery protection circuit outside the rechargeable battery, and the battery protection circuit must take over the function of the current cut-off vent. However, if a PTC element is provided as part of the battery protection circuit, then an increase in volume is inevitable when the battery protection circuit is integrated with the rechargeable battery, which is contrary to the objective of minimizing the increase in external dimensions. Also, reliability suffers when an ordinary battery protection circuit is made to take on the function of a current cut-off vent, making it difficult to obtain a level of reliability at which the rechargeable battery will definitely be protected.
It is an object of the present invention to provide a battery equipped with a battery protection circuit, with which a compact construction that can be applied to a flat-shaped rechargeable battery minimizes the increase in the external dimensions of the rechargeable battery, and with which the battery can be protected by enhancing the function of the battery protection circuit and without providing a PTC element or a current cut-off vent, and which can be used by itself as a battery, without a battery pack configuration being required.
DISCLOSURE OF THE INVENTION
To achieve the above object, a first aspect of the present invention provides a rechargeable battery equipped with a battery protection circuit for protecting this rechargeable battery from overcharging and overdischarging, comprising:
a cell case made of a bottomed cylindrical container, containing therein elements for electromotive force;
a sealing plate for sealing an open end of said cell case;
a protruding terminal provided insulated from the cell case on said sealing plate, said cell case and said protruding terminal being respectively assigned as a positive electrode and a negative electrode of the rechargeable battery;
a connection piece joined to the protruding terminal, a circuit board which includes a plurality of input and output terminals and constitutes a battery protection circuit, and to which said connection piece is connected at a specific location, and a spacer that keeps the circuit board and the cell case apart, all of which are disposed at one end on the side of the sealing plate of the cell case; and
a cover cap disposed so as to envelop the circuit board, the spacer, and the connection piece in a state in which said plurality of input and output terminals on the circuit board are exposed to the outside, and at the same time to cover the peripheral part of the cell case, said cover cap being connected at a specific location of the circuit board.
With the above structure, the rechargeable battery and the circuit board are electrically connected by the cover cap and the connection piece through the positive and negative electrodes of the rechargeable battery, and are integrated by the cover cap. Because the input and output terminals provided on the circuit board are exposed on the outside, the rechargeable battery with its internally integrated battery protection circuit can be handled and used just the same as a rechargeable battery alone.
In the above structure, the cover cap can be provided so as to cover the entire surface of the peripheral part of the cell case, which securely maintains the integration of the rechargeable battery and the circuit board that makes up the battery protection circuit.
Also, if at least one inward cutout is formed in the peripheral part of the cover cap, this is bent inward to hit the top of the cell case, and at least one opening is formed in the peripheral part after it has been bent, the cover cap will be fixed more securely to the rechargeable battery, and at the same time an opening will be formed communicating with the sealing assembly of the rechargeable battery, thereby forming a gas escape hole for releasing any abnormally high pressure inside the rechargeable battery.
The plurality of input and output terminals provided on the circuit board can be disposed asymmetrically, which prevents the cell from being installed backwards.
The outside of the circuit board can be covered with a cover plate provided with windows that open over the input and output terminals, which protects the circuit board.
If the outer side of the mounting location of an IC disposed on the inner side of the circuit board is at least 0.1 mm away from the cover plate, then the electrical effect caused by the application of pressure from the outside to the IC can be prevented.
If the connection piece is disposed on the protruding terminal of the rechargeable battery, and the underside of the circuit board is supported by this connection piece alone or by both the connection piece and the spacer, then the input and output terminals, which are subjected to contact pressure from the device side, will be supported fr
Ishimaru Takeshi
Iwaizono Yoshinori
Kajiwara Shigeru
Kawabe Masaru
Konishi Shoji
Jordan and Hamburg LLP
Martin Angela J
Matsushita Electric - Industrial Co., Ltd.
Ryan Patrick
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