Wave transmission lines and networks – Coupling networks – Nonreciprocal gyromagnetic type
Reexamination Certificate
2002-05-30
2004-09-28
Pascal, Robert (Department: 2817)
Wave transmission lines and networks
Coupling networks
Nonreciprocal gyromagnetic type
C333S032000, C333S119000
Reexamination Certificate
active
06798309
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an arrangement for transmitting electrical signals and/or energy between moving parts that may be disposed along an optional trajectory and that are contacted with each other by galvanic or at least capacitive or inductive means.
PRIOR ART
Electrical signals or electrical energy must frequently be transmitted between parts mobile for rotation relative to each other. A common method to this end uses sliding paths and slip rings. There, the signal or the energy, respectively, which is supplied on a conductor in circular arrangement, is tapped by means of a mobile tapping means. The arrangement need not be inevitably coaxial but rather a certain eccentricity is permissible. Such tapping means may consist of contact springs or also carbon elements permitting an appropriate galvanic contact. It is equally possible to transmit signals or energy, respectively, by capacitive or inductive means, as is described in the German Patent Application P 28 45 438. In the statements presented below, only the term signal or signal transmission will be used instead of the terms “signals or energy, respectively” for the sake of clarity. Moreover, the term “channel” relates to a complete signal channel that is capable of transmitting information simultaneously and consists hence of at least one forward conductor and one return conductor. Several channels may well share a common return conductor. What is essential is the fact that a current flow is created between the signal source and the load or the signal sink, respectively.
A narrow-band signal transmission between parts mobile for rotation corresponds to prior art and involves only slight demands on the transmission system. A wide-band signal transmission, by contrast, involves additional demands on the transmission technology. Here, two fundamental problems must be solved. The first problem is the unwanted or stray radiation or the sensitivity to incident radiation whilst the second problem is a low-distortion signal transmission.
Various provisions have become known for improving the emitted stray radiation or sensitivity to incident radiation. For example, the U.S. Pat. No. 5,530,423 describes complex and expensive shielding provisions that can be manufactured only at unreasonably high costs. In such a case, symmetrical transmission means such as those described in the PCT application PCT/EP 95/01374, for example, are by far more economic. The solution presented in that publication is based on ideal strip-type transmission lines for signal transmission. In practical operation, particularly with application of mechanical sliding paths, additional provisions must be made. Moreover, in the arrangement described here high noise levels and substantial problems in transmission occur when the contact path (implemented here in the form of a strip-type transmission line) is designed as closed ring. Such a design in the form of a closed ring offers, however, substantial advantages in production because the work piece can be machined on lathes in rotational symmetry at acceptable costs. Moreover, a transmission system based on mechanical contacts can be realized exclusively with closed contact paths or else a high level of wear of the contact material would occur at the separation site (gap).
A solution presented in the U.S. Pat. No. 5,018,174 is entirely unsuitable here. In this case, the limit levels required in the advanced EMC standards such as CISPR-11 are exceeded by more than 30 dB, due to the sharp non-symmetry. The approach presented there, which includes a terminating element diametrically opposite to the transmitter, merely leads to an improvement of the signal quality by attenuation of undesirable reflections. The approach improved by the same inventor allows for a symmetrical transmission with enhanced noise-related property, even though this fact is not mentioned expressis verbis. The additional receiver termination requires, however, an unnecessary high expenditure, particularly when the signals are transmitted from the contact path towards a sliding contact because in that case an additional sliding contact is required for termination on the receiver side.
BRIEF DESCRIPTION OF THE INVENTION
The present invention is based on the problem of improving an arrangement for the transmission of electrical signals and/or energy between parts moved for rotation and a contact path closed along the rotating movement, which contact each other by galvanic or at least by capacitive or inductive means, to the effect that noise-free and low-distortion signal transmission can be ensured whilst the EMC limit levels are observed.
One solution to this problem is defined in Claim
1
. Expedient improvements are the subject matters of the dependent claims.
In accordance with the invention, a device according to the introductory clause of Claim
1
is so configured that at least one of the rotatable parts includes a transmitter for feeding the signal and that a terminating element is disposed in an invariable diametrically opposite position. The transmitter is so designed that it feeds a symmetrical signal into the pair of conductors. The terminating element is so designed that it terminates largely the pair of conductors in a reflection-free manner within the frequency range employed for data transmission. As a rule, this will be a termination with an ohmic resistance in correspondence with the natural impedance of the pair of conductors. In certain cases, termination with a combination of dummy elements and resistors may be sensible as well. A receiver is provided for receiving the signals, which evaluates the symmetrical signals of the transmitter. The receiver is disposed for movement relative to the transmitter. The input of the receiver must be designed in a highly resistant form such that it will not cause any noticeably reflections on the pair of conductors. The signal from the pair of conductors may be coupled in towards the receiver also via mechanical sliding contacts in correspondence with prior art, i.e. consist of silver graphite carbon elements or even gold wires, for example. A particularly expedient type of coupling is a capacitive tapping means. In such a case, a small fraction of the signal is coupled out into the receiver in a highly resistant manner and hence free of reflections, specifically via the low coupling capacity between the pair of conductors and a capacitive probe.
In a particularly expedient arrangement, a pair of conductors is provided at least on one of the rotating parts, on which the transmitter and its diametrically opposite termination are fixedly connected. The receiver is then disposed on the other rotatable part and is mobile at different positions relative to the transmitter. The signals are coupled in from the pair of conductors with the fixedly coupled transmitter to the receiver in correspondence with prior art, using mechanical sliding contacts or inductive or capacitive means.
In another expedient embodiment of the invention, a pair of conductors is provided at least on one of the two rotating parts, which is fixedly connected to the receiver. The transmitter and its diametrically opposite terminating element are here coupled via sliding contacts or by inductive or capacitive means in correspondence with prior art. In this case, too, the receiver must present a high input impedance so as to cause only slight reflections on the pair of conductors. The transmitter and its terminating element are expedient connected to each other via a common mechanical structure in such a way that the relative position will be maintained independently of the rotating movement.
In a particularly expedient embodiment of the invention, the terminating element, which is disposed diametrically opposite to the transmitter, is designed as ohmic resistor.
In correspondence with a further expedient embodiment of the invention, the resistance of the terminating element is so dimensioned that it corresponds to the natural impedance of the pair of conductors.
In a particularly expedient
Lohr Georg
Schilling Harry
Pascal Robert
Schleifring und Apparatebau GmbH
St. Onge Steward Johnston & Reens LLC.
Takaoka Dean
LandOfFree
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