Electrical connectors – Interrelated connectors relatively movable during use – Movement about axis
Reexamination Certificate
2002-01-29
2003-05-13
Bradley, P. Austin (Department: 2833)
Electrical connectors
Interrelated connectors relatively movable during use
Movement about axis
C439S028000
Reexamination Certificate
active
06561813
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rotation connector adapted to the transmission of electrical signals from a first device to a second device, which second device is rotatable with respect to the first device. The rotation connector includes a substantially dielectric support member having a longitudinal direction and provided with a first end portion and a second end, wherein the support member comprises an electrically conductive track extending in the longitudinal direction as far as the region of the second end portion, a self-supporting contact ring having a substantially circular electrically conductive peripheral edge and an inner edge defining a recess around the center-line of the contact ring, said contact ring being fixed on the support member. The recess substantially encloses the support member in such a manner that the center-line of the contact ring is substantially parallel to the longitudinal direction of the support member. The peripheral edge of the contact ring is connected to the track via an electrically conductive path. The present invention also relates to a contact ring, an insulator element, and a support member for use in such a rotation connector. In addition, the invention relates to a method of making the rotation connector.
2. Related Art
A connector of this kind, which is also known as a slip ring, is known from the prior art.
FIG. 1
is a diagram of a rotation connector of this kind. This connector is made as follows: In a first step, an electrically conductive wire provided with an insulating coating is soldered or spot-welded to the inner edge of a (frequently) brass contact ring. As many contact rings as are necessary for the type of connector can be made in this way. A first contact ring is then placed in a jig. A second contact ring is then pushed over the wire fixed to the first contact ring and the second contact ring is placed close to the first contact ring so that they do not make contact with one another. A third contact ring is then pushed over the two wires of the first and second contact rings, and this third ring is pushed close to the second contact ring, again without making contact. A row of contact rings is built up in this way. The row is then embedded, possibly via an injection moulding process, in a dielectric plastic which after cooling and/or chemical hardening forms a rigid support member for the contact rings. As a result, the contact rings are permanently fixed and insulated from one another in the connector. In addition, the wires which serve as electrically conductive tracks from the respective contact rings to the second end of the rotation connector, are rigidly fixed in the plastic on the inside of the support member. The next step is to turn the injection moulding in a lathe so that the conductive cylindrical surface of the contact rings is exposed. Finally the connector is provided on the outside of the contact rings with a brush which includes a plurality of individual brush elements as there are contact rings in the connector. The brush provides the electrical contact between the contact rings and the surroundings of the connector. In this way conductive connections can be made between the brush and the wires which emerge at the second end of the rotation connector.
The connector is used by connecting the brush to a first device and by connecting the wires emerging from the connector near the second end portion to a second device which can rotate with respect to the first device. With this construction of the connector, the electrical contact between the two devices is maintained even when the second device rotates with respect to the first device.
The known rotation connector, however, has a number of significant disadvantages. Above all, the assembly of this known connector involves a very labor-intensive process. Thus placing the contact rings over the wires of the preceding rings cannot be automated, so that this operation requires considerable expensive working time. In addition, during the moulding of the plastic support member, there is a considerable risk that one or more of the wires on the inside of the contact rings will work loose, because the soldered or spot-welded connection is mechanically weak. Also, after the moulding of the plastic support member, each connector must be individually finished on a lathe. Not only is this also a labor-intensive operation, but it also increases the risk of defects, for example a complete breakage of the connector or breakage of the emerging wires, in the connector which has already been largely assembled. Such defects, e.g., the working loose of a soldered connection as described above, cannot be remedied after the support member has been moulded. This means that the production costs due to rejects of practically completely assembled connectors become even more expensive. Another significant disadvantage is that the wires extend substantially through the center of the support member. In this way it is difficult, particularly in the case of small connectors, to combine the same with other forms of signal transmission for which space is required in the connector. Thus, in modern communications technology, signal transmission is frequently effected by optical fibers, which can hardly be accommodated, if at all, in the support member, because there is practically no room for them, while on the other hand the support member is not sufficiently transparent for direct transmission of optical signals, due to the presence of the wires. Even for other more conventional signal transmission, such as capacitative and inductive transmission, the known connector is unsuitable because components would have to be accommodated in the core of the support member for this purpose. Although that is not completely impossible, it would result in connectors which are difficult to miniaturize, if they can be miniaturized at all.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a rotation connector which is simple to assemble and which is adapted to being combined with a second form of signal transmission. To this end, a rotation connector according to the preamble of claim 1 has been developed, wherein the track is disposed on the surface of the support member. The connector according to the present invention is made by providing the surface of the support member with at least one conductive tracks, for example in the form of a thin metal layer. The contact ring is then pushed over the support member in such manner that it makes electrically conductive contact with the track. A second contact ring can then be pushed over the support member in the direction of the first, and this contact ring makes contact with a second track. In this way, the connector can be constructed very simply and by automatically. Any defects, for example a non-functioning contact ring, can easily be remedied by removing such contact ring from the connector and replacing it by another. A defect in a track, for example a break, where no electrically conductive through the connection is achieved, can also easily be remedied by removing the contact ring or rings from the connector and repairing the track. Also, the construction of the connector according to the present invention enables the support member to be made hollow so that other components can be accommodated in the cavity, for example, a means for the optical transmission of data from the first device to the second device.
In one embodiment, the track is formed as a first profile in the surface of the support member and, the inner edge of the contact ring is provided with a second profile which is in operative connection with the first profile. This embodiment offers the advantage that the assembly of the connector is further simplified because it is then possible to form the contact ring in such a manner that it can be pushed on the support member in only one way with the conductive contact being, at all times, formed via the co-operating profiles. It also offers the possib
Rutten Hendrik Gerard Jozef
Verzijl Klaas
Bradley P. Austin
Gushi Ross
Oce--Technologies B.V.
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