Electricity: conductors and insulators – Anti-inductive structures
Reexamination Certificate
1999-03-03
2001-07-24
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Anti-inductive structures
C174S033000
Reexamination Certificate
active
06265655
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a signaling connection of the type formed by at least two electric conductors by; means of which different components and/or subassemblies can be connected.
2. Description of the Prior Art
A signaling connection of the above general type can serve to connect a TTL-IC to an opto-coupler via at least two electrical conductors, for example. Of the at least electrical conductors, one serves as a reference potential line, and the other electrical conductor or conductors serve as signal lines.
In a highly magnetically disturbed environment, e.g. given a proximate magnetic resonance device or proximate power transistors, such high voltages can be induced in the electrical conductors such that functional disturbances may arise which render a reliable signal transmission impossible.
In order to prevent this kind of magnetic interference, it is known to utilize coaxial cable for signal transmission. Coaxial cable, as is well-known, has concentrically arranged electrical conductors in which voltages arising from electrical interference fields are discharged as long as the electrical conductors do not form a closed loop (loop area equals zero). Thus, magnetic interference fields do not influence the signal-carrying electrical conductors.
It is also known to twist electrical conductors in pairs. This technique does not work as well as a coaxial line, however, and must therefore often be applied in combination with a precisely defined laying (i.e., path selection) of the twisted pair, which can result in corresponding added costs.
It is also known to provide filters in electrical cables and conductors, with not insignificant extra costs. The insertion of filters is often not possible, however, since the filters unavoidable influence, and may thus cause a falsification, of the transmitted signals.
German OS 31 45 039 teaches an integrated semiconductor circuit which is arranged on a substrate and which has a number of signal-carrying conductors runs on this substrate. In order to reduce the reciprocal electrical influence of a first signal-carrying conductors run, which transmits a first signal, and a second signal-carrying conductors run, which transmits a second signal, a third signal-carrying conductors run is arranged on the substrate. The third signal-carrying conductors run transmits a third signal whose phase is opposite the phase of the first signal. On the basis of the oppositely phased feeding of a signal into the third signal-carrying conductors run, electrical interference fields between the first and the second signal-carrying conductors runs are compensated by opposite electrical interference fields between the second and third signal-carrying conductors runs.
The layouts depicted in FIG. 3 and FIG. 5 of German OS 31 45 039 represent an expensive realization of twisted-pair conductors on the semiconductor level. The electrical influence of the second signal-carrying conductors run is reduced by the twisting of the third signal-carrying conductors run with the first signal-carrying conductors run. Outer magnetic disturbances are also compensated in small measure by the twisting.
In the variants depicted in FIG. 2 and FIG. 4 of German OS 31 45 039, the electrical fields of the first and second signal-carrying conductors runs are compensated, however, the magnetic interference is twice that in a layout according to
FIG. 1
with only first and second signal-carrying conductors runs.
The compensation measures described in German OS 31 45 039 always presume that both the aforementioned first and second conductors runs conduct signals. If only one of these two conductors runs conducts a signal, then this compensation measure is not suitable.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a signaling connection of the above-described type wherein a reliable and cost-effective signal transmission is insured, even in the presence of strong magnetic interference, and which is independent of the arrangement of the components subassemblies connected by the signaling connection.
The object is achieved in a signaling connection of the above type according to the invention wherein at least one additional electrical conductor is connected at both ends to one of the aforementioned two electrical conductors, such that voltages induced by magnetic interference fields are compensated.
The inventive connection of a third conductor to one of the other two conductors also achieves the object because any magnetic interference field which is emitted between the first two electrical conductors is compensated by a magnetic interference field which is emitted between one of these electrical conductors and the third electrical conductor.
At least two electrical conductors connect different components and/or subassemblies. The one additional electrical conductor is arranged such that voltages that are induced by magnetic interference fields are compensated.
The additional conductor or conductors is/are exposed to the same magnetic interference field as that which affects the electrical conductor or conductors which conduct a signal. The voltages induced by the magnetic interference field are thus cancelled out vectorially, thereby compensating the induced voltages (known as distant field compensation).
In the case of an external source of interference, the at least one additional conductor functions to suppress interference to the at least one electrical conductor which conducts a signal, rather than shielding against magnetic interference fields or a discharging a voltage arising from an electrical interference field. The inventive solution thus offers considerable cost advantages. Also, the signaling connection itself is not subjected to any limitations with respect to the laying of its electrical conductors.
In the case of a magnetic interference field produced within one of the components ir subassemblies which are connected by the signaling connection, any magnetic interference field which is emitted between the electrical conductors is inventively compensated by a magnetic interference field which is emitted between one of the electrical conductors and the additional electrical conductor.
Such interference sources in the connected components or subassemblies are, for example, components of power electronic circuits which are arranged on a neighboring motherboard and which interfere intensely, via their electrical conductors, with the signal transmission between the TTL-ICs and the opto-couplers, which are arranged together on another motherboard.
The inventive principle can be realized in nearly all types of signaling connections, for example, connections produced by ribbon cables, plug connectors or printed boards.
As used herein, “component” means electronic, electric and electromechanical components. Analogously, the term “subassembly” means electronic, electric, and electro-mechanical subassemblies. The term “electronically operating device” generally encompasses “components” and “subassemblies”.
REFERENCES:
patent: 4734696 (1988-03-01), Rogers
patent: 4754102 (1988-06-01), Dzurak
patent: 4764939 (1988-08-01), Rogers
patent: 4837405 (1989-06-01), Bonjour et al.
patent: 4945189 (1990-07-01), Palmer
patent: 5033091 (1991-07-01), Bond
patent: 5523528 (1996-06-01), Bese et al.
patent: 5831210 (1998-11-01), Nugent
patent: 5965956 (1999-10-01), Bochme et al.
patent: 31 45039 (1982-10-01), None
Mayo III William H.
Reichard Dean A.
Schiff & Hardin & Waite
Siemens Aktiengesellschaft
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