Device for reverse polarization protection for a battery

Details Device for reverse polarization protection for a battery Device for reverse polarization protection for a battery

2000-08-10

2001-09-18

Tso, Edward H. (Department: 2838)

Electricity: battery or capacitor charging or discharging

Cell or battery charger structure

For battery pack

C320S165000, C429S001000

Reexamination Certificate

active

06291970

ABSTRACT:

FIELD OF THE INVENTION
The present disclosure relates generally to protection of electrical batteries and more particularly to preventing such batteries from making electrical connection when installed in the reversed polarity condition.
BACKGROUND
The standard rectangular shaped 9 volt “transistor radio” battery is used in a wide variety of products (e.g., portable radios, smoke detectors, cameras). In this battery type, the positive and negative terminals are at one end of the battery. To prevent damage to the product, it is often necessary to prevent the battery terminals from improperly electrically connecting with the electrical contacts of the product in which the battery is installed. The battery terminals themselves are configured to facilitate this, in that one terminal is adapted to be a “male” connector and the other terminal is adapted to be a “female” connector, each also having a different diameter. When the device is electrically connected to the battery via a mating cable connector, proper battery polarization is automatically achieved, because per its description, it has two connectors, each of which “mate”, or mechanically cooperate, only with one of the male and female connectors on the battery.
However, because product manufacturer may find it more convenient to install batteries in a product without the use of a mating cable connector, and because it is often easier and less expensive to manufacture a product without a mating cable connector, in many applications it is preferable to make a pressure contact against the terminals of the battery with a spring mechanism of some type, rather than using a mating cable connector. In these applications, protecting the product from reverse polarization when incorrectly installed requires some form of mechanical interference. However, due to variation in the lengths of different brands of batteries and tolerance variations within a brand, there is a need for a reverse polarization protection method that compensates for different battery lengths.
SUMMARY
A device providing reverse polarization protection for a battery having both positive and negative terminals disposed at one end of the battery (e.g., a 9 volt “transistor radio” battery) is described. The device is adapted for insertion between the terminals of such a battery and conventional battery spring contacts in a battery housing. The device is mostly planar and made from an insulating material (e.g., plastic), and has two openings of unequal size defined through it. The first opening has a diameter to accommodate a negative terminal of the battery, while the second opening has a diameter slightly larger than that of a positive terminal of the battery. The second opening is sized such that the (larger) negative terminal of the battery cannot pass through it, thus providing the mechanical interference for reverse polarity protection.
The device in one embodiment moves freely in conjunction with spring contact compression/decompression, while being retained within the battery housing of the product. Since the device is able to move, or “float”, it is possible for the product's battery spring contacts, which are present anyway, to be the only compliant components in the design.
The present device is especially useful in low-cost applications where the battery housing is made from plastic, since the device can be fabricated from the same mold as the battery housing at little additional cost. The device is also useful in applications where use of a mating cable connector for providing battery reverse polarization protection is not desirable. The device is not limited to use with the standard 9 volt type batteries.


REFERENCES:
patent: 4084037 (1978-04-01), Morton
patent: 4595641 (1986-06-01), Giurtino
patent: 4972135 (1990-11-01), Bates et al.
patent: 5229220 (1993-07-01), Stanton et al.
patent: 5376476 (1994-12-01), Eylon
patent: 5906505 (1999-05-01), McCurdy, Jr. et al.

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