Electrical connectors – Coupling part having handle or means to move contact... – Expandable – prong receiving socket
Reexamination Certificate
1999-11-10
2001-07-10
Patel, Tulsidas (Department: 2839)
Electrical connectors
Coupling part having handle or means to move contact...
Expandable, prong receiving socket
Reexamination Certificate
active
06257911
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention is related in general to low insertion force electrical connectors, and, in particular, to a low insertion force electrical connector having a wipe feature when the connectors are mated.
BACKGROUND OF THE INVENTION
Prior art connectors have been provided for electrically connecting two electric circuits, such as those found on circuit boards. One example is a pin-type connector and another example is an edge connector of printed circuit boards. Typically, an interference fit between the contacts of mating connectors provides a scraping action which wipes clean the surfaces of the mating contacts. However, when a large number of contacts are mated between two connectors with wiping engagement, the forces required to mate the two connectors often becomes quite large. Another problem with connectors having a wipe feature is that a full-stroke contact wipe causes excessive wear to the mating surfaces of the contacts. Some connector contacts are typically rated for a limited number of wipes, such as some gold contacts which are rated for only a few cycles. Other prior art connectors have been provided with a low insertion force feature in which a cam member is spring biased to separate two spaced-apart contacts with a clearance for passing the contact of a mating connector. Insertion of the mating connector into the low insertion force connector pushes the cam member against the bias spring, allowing the spaced-apart contacts to move toward one another and to engage the contacts of the connector being mated. These prior art low insertion force connectors have only one contact per mating connector contact, and not two separately insulated contacts.
Another problem with prior art connectors occurs in those used for testing circuits using a high voltage potential, often called “High-Pot Testing.” The high potential voltages applied in such tests often result in a large driving current being applied across the mating surfaces of the contacts. In some circumstances, a Kelvin test configuration may be used in which pairs of contacts are used for each connection to a unit under test, wherein one contact is used for driving the test current, or as the high voltage contact, and a second contact is used to take test measurements. When Kelvin test configurations are used, the electrical connections between mating leads are typically maximized by using wiping engagements and high contact pressures when the test contact connections are mated in order to reduce the voltage potential drop across the interface of the test contacts. However, with increasing miniaturization of circuitry, Kelvin test configurations have become increasingly difficult to implement due to significant decreases in contact spacings. With decreased contact spacings and further reductions in sizes of the contacts to fit within such spacings, the wear ratings of such contacts are rated for even fewer cycles of mating and breaking connections, especially if a full length wipe is used for the contacts during connector mating.
SUMMARY OF THE INVENTION
A low insertion force connector has contact assemblies which provide a limited wipe during the insertion stroke of a mating contact, and two separate circuit paths with each of the contacts of the mating unit in a Kelvin test arrangement. The contact assemblies include a plunger which is moveably mounted within a housing and has an exterior periphery which defines a cam surface and a contact surface. The plunger is moveably disposed within the housing for engaging the mating unit and moving from an extended position to a retracted position. The contact assemblies further include a bias member which biases the plunger into the extended position, and a contact member having a biasing portion, a contact portion and a mating periphery which is mounted to the housing and moved by the plunger to a position which is spaced apart from a contact position located adjacent to an aperture in the housing. An insulator extends between the biasing portion of the contact member and the plunger for electrically isolating the contact member from the plunger when the plunger is disposed in the retracted position. Insertion of the mating unit into the aperture engages the mating unit with the plunger, moving the plunger from the extended position to the retracted position with the plunger electrically coupled to the contact of the mating unit in a first electrical connection providing a first circuit path, and the contact portion of the contact member also engaging the contact of the mating unit in a second electrical connection providing a second circuit path. In a production testing environment, the mating contacts may be cleaned by spraying with a solvent or a discharge of air when being inserted into a connector contact assembly.
REFERENCES:
patent: 3171183 (1965-03-01), Johnston
patent: 4334193 (1982-06-01), Gordy et al.
patent: 4542950 (1985-09-01), Gillett et al.
patent: 4591222 (1986-05-01), Shaffer
patent: 4655526 (1987-04-01), Shaffer
patent: 4684193 (1987-08-01), Havel
patent: 4773873 (1988-09-01), Hillis
patent: 4867697 (1989-09-01), Borges
patent: 5504435 (1996-04-01), Perego
patent: 5601443 (1997-02-01), Stinsky et al.
Goodman James B.
Shelby Frank S.
Fink David
Nasri Javaid
Patel Tulsidas
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