Electrical connectors – Interrelated connectors relatively movable during use – Movement about axis
Reexamination Certificate
2003-01-10
2004-03-30
Luebke, Renee (Department: 2833)
Electrical connectors
Interrelated connectors relatively movable during use
Movement about axis
Reexamination Certificate
active
06712618
ABSTRACT:
FIELD OF THE INVENTION
This invention pertains to electrical connections, and more particularly relates to electrical rotary connectors.
BACKGROUND OF THE INVENTION
Slip rings are used in a variety of applications to transfer electrical signals, including power signals, between components where one component rotates in relation to another component. One application where slip rings are used is in magnetic chucks to transfer power from the stationary frame of the magnetic chuck to the magnetic chuck rotating assembly. The slip ring is typically composed of a metal ring upon which a graphite material brush (and the like) rubs and transfers the signal. The metal ring or the graphite material brush rotates.
FIG. 6
illustrates a typically slip ring assembly
10
. The brush
12
is placed in a sleeve of a brush holder
14
. The brush
10
is in electrical contact with brush connection
16
and a wire assembly
18
is connected to the brush connection
16
. During operation, the brush contacts a conductive metal ring
20
. A connection point
22
is attached to the ring
20
and wire leads
24
are connected to the connection point. As the ring
20
or brush
12
rotates, the brush
12
rubs against the ring
20
and signals are transferred across the brush/ring interface
26
. The ring
20
and/or the brush
12
is connected to a rotating member of a device (not shown).
The operation of the slip ring is technically simple. However, there are a number of problems with slip rings in magnetic chuck applications. The brush wears down over time, which leads to degradation in the efficiency of transferring power and degradation of signal quality. Additionally, the brush and metal ring typically have high resistance, which results in power loss due to I
2
R heating losses. The resistance varies due to oxidation and other factors, which increases power losses and the fluctuations causes electrical noise. Additionally, the slip rings may need high levels of maintenance to remove the debris causes by the wear of the brushes and to replace the brushes. Other problems include electrical arcs that are produced as the slip ring assembly rotates. The arc, in combination with other factors, can lead to demagnetization problems with the magnetic chuck.
BRIEF SUMMARY OF THE INVENTION
The invention provides brushless rotary connector for use in magnetic chuck applications and the like. The rotary connector uses a housing having a sealed metal fluid with sliding contacts capable of handling high current levels. During rotation, the fluid maintains the electrical connection between the contacts without any wear, and the use of the liquid metal as a conduction path offers an extremely low resistance connection that is constant.
The housing is mounted in a base that serves as a support for the housing and for connections to the stationary component. The rotating member of the rotary connector is connected to a ring that is attached to the rotating member of the magnetic chuck. This connector is a simple, low cost and highly reliable connector. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.
REFERENCES:
patent: 5342067 (1994-08-01), Adler et al.
patent: 6299453 (2001-10-01), Matsumoto
patent: 2001/0007799 (2001-07-01), Matsumoto
Figueroa Felix O.
Leydig Voit & Mayer LTD
Luebke Renee
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