Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
1999-02-05
2001-03-13
Gandhi, Jayprakash N. (Department: 2841)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S752000, C361S801000, C174S051000, C439S095000, C024S563000
Reexamination Certificate
active
06201710
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a housing configuration for a printed circuit board equipped with components, including a housing with at least partially metallic housing walls as well as at least one metallic spring profile element, the spring profile element having a first and a second profile leg connected to one another forming an essentially V-shaped profile cross section, the first profile leg being electrically connected to a ground terminal of the printed circuit board, and the second profile leg exerting an elastic spreading force as it bears against the housing wall and makes electrical contact with the latter.
In many areas of technology, electrical equipment must satisfy increasingly more stringent requirements with regard to electromagnetic compatibility (EMC). A measure which is already known for that purpose is electrically connecting a ground terminal of a printed circuit board (EMC ground) to a metal housing that accommodates the printed circuit board, and achieving electromagnetic shielding as a result thereof.
European Patent Application 0 557 545 A1 describes a housing for equipment appertaining to electrical communications technology, which has a chamber-like structure created by inner housing walls. The electromagnetic shielding by the housing is achieved by virtue of the fact that contact strips are provided on the printed circuit board. Profiles of the contact strips correspond to contours of the chamber walls. The contact strips are provided with contact springs which project upward in an inclined manner and contact pins that are bent away perpendicularly downward. That solution is structurally complex and requires high dimensional stability for the fitting of the contact strips. Moreover, it is disadvantageous that the contact strips have to be attached to the printed circuit board before the latter is inserted into the housing.
German Utility Model G 91 09 072.5 describes a housing for a hand-held radio telephone, in which the electromagnetic shielding is effected by a metallic shielding plate which covers the printed circuit board. The shielding plate has feathered edges which make electrical contact with the housing shell when the latter is put in place.
A housing configuration which is constructed as set forth initially above is described in International Patent
Application WO 96/19098. In order to ground a circuit board, that document proposes the use of a U-shaped spring element which is fixed by one of its legs to the circuit board, bridges a gap between the circuit board, and at the same time bears against the housing wall with its other leg. A vertex of the U in that case is disposed above the circuit board.
A further metallic grounding spring is described in German Patent DE 37 90 062 C2.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a housing configuration for accommodating an electrical circuit having a printed circuit board equipped with components in a housing, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type, which enables a printed circuit board ground to make contact with the housing in a structurally simple and effective manner and which furthermore allows high flexibility in the course of carrying out an assembly sequence.
With the foregoing and other objects in view there is provided, in accordance with the invention, a housing configuration for a printed circuit board equipped with components and having an edge, end surfaces and a ground terminal, comprising a housing having an at least partially metallic housing wall defining a gap region between the housing wall and the edge of the printed circuit board, the housing having at least one metallic spring profile element inserted into the gap region; the spring profile element having a first profile leg and a second profile leg connected to one another forming a substantially V-shaped profile cross section; the first profile leg electrically connected to the ground terminal of the printed circuit board and bearing against one of the end surfaces of the printed circuit board; and the second profile leg exerting an elastic spreading force while bearing against and electrically contacting the housing wall.
The pressure force effected by the V-shaped cross section of the spring profile element ensures permanent and ample bearing of the second profile leg against the inner wall surface of the housing and, at the same time, ensures the required low-resistance contact-making between the printed circuit board ground and the housing. At the same time, the V-shaped profile cross section enables tolerance compensation of a gap dimension between the printed circuit board and the housing. That affords advantages in terms of production engineering, particularly when different printed circuit board or housing dimensions occur during production.
In accordance with another feature of the invention, the first profile leg has a bulge which engages behind the underside of the printed circuit board in the inserted state. The effect achieved by the bulge of the first profile leg engaging behind the underside of the printed circuit board is that the spring profile element latches in the gap region between the housing wall and the printed circuit board and a stop piece rests with a defined pressure on the ground terminal of the printed circuit board. A reliable mechanical fit and good electrical contact-making are ensured in this way.
A further advantage is the fact that the spring profile element can be fitted only after all of the functional tests have been carried out, at the end of the assembly sequence. Consequently, housing configurations without a spring profile element can be subsequently equipped in a simple manner with the element without necessitating the disassembly of the electrical circuit configuration with a printed circuit board for this purpose.
In principle, the first profile leg can be electrically connected to the printed circuit board ground in a variety of ways.
In accordance with a further feature of the invention, the first profile leg is provided, on its leg end, with a stop piece which protrudes essentially at right angles from the profile leg and is seated on the ground terminal provided on the surface of the printed circuit board. In terms of production engineering, it is then possible to solder the spring profile element to the ground terminal of the printed circuit board at the stop element before the printed circuit board is incorporated into the housing. In this case, the printed circuit board is inserted into the housing with the spring profile element which is already fixedly connected to the printed circuit board, and contact between the spring profile element and the housing wall is made automatically.
As already mentioned, however, the inventive spring profile element with the stop piece also enables a different assembly sequence, which is advantageous particularly when it is important for the housing configuration according to the invention to have high ease of repair and capability of reassembly. In this case, the spring profile element is not pressed into the gap region between the housing and the printed circuit board until after the assembly of the electrical circuit configuration. The stop piece in combination with the bulge of the first profile leg which engages under the circuit board as well as the spreading effect of the spring profile element ensures the correct end position of the spring profile element and simultaneously forms the electrical contact with the ground terminal.
In accordance with an added feature of the invention, the second profile leg is provided with transverse recesses, which are worked into the profile leg from the longitudinal edge of the leg. This increases the flexibility of the second profile leg in the longitudinal direction, thereby obtaining constant, and consequently low-resistance, bearing of the second profile leg along the housing wall even if the housing should have any slight wall curvat
Bagung Detlev
Ludwig Gunter
Gandhi Jayprakash N.
Greenberg Laurence A.
Lerner Herbert L.
Siemens Aktiengesellschaft
Stemer Werner H.
LandOfFree
Housing configuration for a printed circuit board equipped... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Housing configuration for a printed circuit board equipped..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Housing configuration for a printed circuit board equipped... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2459355