An RFI through-let for screening signals

Abstract: The present invention relates to an RFI through-let for screening signals transmitted between different components, for instance circuit boards, of which one component is arranged in a screened space. The through-let includes signal-transmission through-let capacitors which are counted in a screen plate intended to be positioned in a rectangular opening in the side-wall of the screened space. According to the invention, the screen plate (3) is comprised of a front part (3) which includes a rectangular, generally flat plate having tongues or tabs (7) disposed along the sides thereof and also having a central, rectangular hollow (9), and a holding part (5) which is soldered firmly in the vicinity of the hollow (9) of the front part (3). The holding part (5) includes a flat plate whose long sides are bent to form guide flanges (11) which extend perpendicularly downwards away from the front part (3), along a first line (A) corresponding to the long sides of the opening (6), and along a second line (B) downwardly of the first line are further bent inwardly towards one another. Parts (12) punched-out along the first line (A) cause shoulders (13) to be forced in the second bending operation, these shoulders projecting upwards and outwards towards the front part and are intended to grip-in behind the side-wall (4) of the space when fitting the screen plate (1) and therewith hold the screen plate firmly in the opening.

Description: TECHNICAL FIELD The present invention relates to a RFI through-let for screening signals transmitted between different components, for instance circuit boards, of which components one is mounted in a screened space, the RFI through-let comprising signal-transmission through-let capacitors which are mounted in a screening plate intended to be mounted in a rectangular opening in the side wall of the screened space. BACKGROUND ART Screened RFI-signal through-lets (RFI = Radio Frequency Interference) of the aforesaid kind are known to the art. These through-lets, however, are often of complicated construction and the work involved in fitting the actual through-let and in mounting the through-let in the associated equipment is time-consuming. As a result, difficulties arise in achieving a complete screen around the through-let, and also results in problems of keeping the through-let in position in the screen wall. DISCLOSURE OF THE INVENTION The object of the present invention is to provide a screened RFI through-let of the aforesaid kind which is of simple and reliable construction,which can be fitted without requiring time-consuming procedures, and which can be applied simply and quickly and which will remain seated in the opening, while nevertheless affording a fully safe screen. This is achieved with a through-let having the characteristic features set forth in the following Claims. Thus, the advantages afforded by the inventive through-let reside in a simple construction comprising only a few parts, reliable screening, and rapid fitting and application. Further objects of the invention and advantages afforded thereby will be apparent from the following description, in which the invention is described in more detail with reference to a preferred exemplifying embodiment thereof and also with reference to the accompanying drawing. BRIEF DESCRIPTION OF THE DRAWING Figure 1 is a top view of an inventive RFI through-let. Figure 2 illustrates the through-let in side view and partially in section, and shows the through-let mounted in a chassis. Figure 3 is another side view of the through-let. Figure 4 illustrates a detail of the through-let. BEST MODE OF CARRYING OUT THE INVENTION Figure 1 is a top view of the inventive RFI through-let. The through-let includes a screen plate 1 in which a number of signal-transmission through-let capacitors 2 are mounted. The capacitors 2 are connected to electronic components, such as circuit boards, in a suitable manner, of which components one is mounted in a screened space. The described and illustrated embodiment has eight capacitors, although it will be understood that this number can be varied in accordance with the requirement for necessary signal transmissions. The screen plate 1 is comprised of two parts, a front part 3 which lies against the side-wall 4 of the screened space, and a holding part 5 which holds the through-let in position in an opening 6 in the side-wall of the space, see Figures 2 and 3. The front part comprises a rectangular, generally flat plate having disposed along the sides thereof tabs or tongues 7 which lie in resilient, screening contact with the side-wall 4. Contact with the side-wall can be improved by providing the tongues 7 with projections or beads 8. The plate is provided with a central hollow 9 which has disposed in the flat bottom thereof a number of holes, the number corresponding to the number of signal transmission capacitors 2. The holding part 5 comprises a rectangular flat plate whose two opposing short-sides have been bent "up" at right angles against the front part 3 when the screen plate 1 is fitted, to form positioning flanges 10 which determine the position of the screen plate longitudinally in the opening 6, as illustrated in Figure 2. As will be seen from Figure 3, the long sides of the holding part 5 are first bent "down" at right angles along a line A corresponding to the long sides of the opening 6 away from the front part, and are thereafter further bent, slightly inwards towards one another along a line B to form guide flanges 11 which guide the screen plate 1 in the opening when fitting the through-let. Two U-shaped parts 12 punched-out along the line A on each long side cause shoulders 13 to be formed when bending along the line B, these shoulders projecting obliquely upwards and outwards in relation to the front part 3. The shoulders 13 are adapted to snap-in behind the side-wall 4 of the space when fitting the screen plate 1, and to hold the screen plate in position in the opening 6. The holding part 5 is also provided with a number of holes corresponding to the number of signal transmission capacitors 2. The screen plate 1 is assembled by soldering together the front part 3 and the holding part 5, with the holes in respective parts coinciding with one another, whereafter the signal transmission capacitors 2 are mounted in the holes and soldered therein. The screen plate is fitted by placing the screen plate in the opening 6, wherein the guide flanges 11 guide the screen plate laterally and the positioning flanges guide the plate longitudinally. The shoulders 13 snap-in behind the side-wall 4 and hold the screen plate firmly in position. It will be understood that the invention is not restricted to the aforedescribed and illustrated embodiment thereof, and that modifications can be made within the scope of the following Claims.

Claims: An RFI through-let for screening signals transmitted between different components, for instance circuit boards, of which one is arranged in a screened space, the RFI through-let comprising through-let capacitors (2) for signal transmission mounted in a screen plate (1) intended to be mounted in a rectangular opening (6) in the side-wall (4) of the screened space, characterized in that the screen plate (1) comprises a front part (3) which includes a rectangular, generally flat plate with tongues or tabs (7) disposed along the sides thereof and having a central, rectangular hollow (9), and further comprises a holding part (5) which is soldered firmly to the hollow (9) of the front part (3) and which includes a flat plate whose long sides are bent to form right-angled guide flanges (11) which extend down from the front part (3) along a first line (A) corresponding to the long sides of the opening (6) and along a second line (B) downwardly of the first line are bent further inwards towards one another, wherein parts (12) punched-out along the first line (A) result in the formation of shoulders (13) in the second bending operation, these shoulders projecting upwardly and outwardly towards said front part (3) and being adapted to grip-in behind the side-wall (4) of the space when fitting the screen plate (1), thereby holding the screen plate firmly in said opening (6). A through-let according to Claim 1, characterized in that the front part (3) and the holding part (5) are provided with mutually coinciding holes in which the signal transmission capacitors (2) are firmly soldered. A through-let according to Claim 1, characterized in that the tongues (7) are provided with beads (8) which face towards the side-wall (4) of the space. A through-let according to Claim 1, characterized in that the holding part (5) is bent upwards at its short sides towards the front part (3) to form positioning flanges (10) which determine the longitudinal position of the screen plate (1) in the opening (6).

Inventors: HANSSON KJELL OLOV, OVANFORS ERIK LENNART, HANSSON, KJELL OLOV, OVANFORS, ERIK LENNART
Applicants: ERICSSON TELEFON AB L M, TELEFONAKTIEBOLAGET L M ERICSSON
Application year: 1992
Main classification: G12B17
IPC codes: H01R13, H05K9