Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Patent
1995-09-25
1997-04-01
Bradley, P. Austin
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
439 55, 439 97, 361794, H05K 714
Patent
active
056172990
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a connecting rear wall having plug-and-socket devices arranged on a connecting board for making mutual contact between electronic and/or electromechanical plug-in modules in subracks, and having the potential leads of at least one power supply unit.
Modules assembled using plug-in design and operated with one another in a subrack are in general use, in particular for equipment in data systems technology. High demands are placed on this equipment with regard to the suppression of high-frequency interfering radiation. Since the production of such interference on the modules cannot be avoided, the latter and/or the subrack are generally designed as a screening cage.
A problem arising in this case is the connecting rear wall, which on the one hand leaves the rear of the subrack open, and on the other hand carries connecting lines which act as transmitting antennas for the interfering radiation. It is difficult to screen them, in particular in the case of subracks into which modules can be plugged from two opposites sides and in the case of which, therefore, the connecting rear wall is situated in the middle of the subrack. Such a subrack is disclosed, for example, in DE 36 08 046 A1. It is already known from U.S. Pat. No. 3,992,686 to construct the connecting rear wall as a multi-layer printed circuit board, and in this case to use one layer to carry the zero potential and thus as a large-area high-frequency screen (ground plane). A further layer carries a supply voltage.
It is disadvantageous in this arrangement that the screen has as small cross-sectional area, and is thus generally--although mostly at zero potential--suitable only conditionally as a current-carrying conductor for the power supply. The same holds for the layer carrying the supply voltage. Consequently, use is made in addition of conductors of relatively large cross-section to carry the current. However, from the point of view of electronic engineering, the latter form with the screen potential loops which can often be mastered only with difficulty.
It is an object of the invention to provide a connecting rear wall of the type mentioned at the beginning which has an improved screening effect against high-frequency interfering radiation, and is simple to disassemble for the purpose of enabling ease of recycling.
SUMMARY OF THE INVENTION
The present invention achieves the aforementioned objects by providing an improved connecting rear wall. According to an embodiment of the invention, at least one connecting board is provided, each having receptacles for receiving plug-in modules. At least two metal plates are provided and arranged in a spaced parallel, stacked manner relative to the connecting boards. For example, in an embodiment including two connecting boards, the metal plates are arranged between the connecting boards. Each metal plate is connected to a respective voltage source. At least one metal plate carries a ground potential, and another carries a supply voltage. A plurality of contact areas are disposed on each connecting board, which are operably connected to the plug-in receptacles. The metal plates have lugs, each of which is essentially a Z-shaped bend forming an offset end face positioned to contact an associated one of the contact areas. The Z-shaped lugs pass through cutouts or through-openings in the other plates at a predetermined clearance distance.
In a preferred embodiment, the metal plate carrying ground potential is larger than the supply voltage plate. The larger plate has bent ends to partially surround the smaller plate for improved shielding and interference reduction.
In an embodiment, more than two metal plates can be provided. In such an embodiment, two or more supply voltage levels can be provided to the connecting boards.
The metal plates serve in this arrangement simultaneously as a screen and as a single conductor in each case for the supply currents and their return. Since, by contrast with the printed conductor tracks, they can be provided with a sub
REFERENCES:
patent: 3992686 (1976-11-01), Canning
patent: 5023754 (1991-06-01), Aug et al.
Gockel Ludger
Knoop Franz-Josef
Bradley P. Austin
Patel T. C.
Siemens Nixdorf Informationssysteme Aktiengesellschaft
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