Function unit for electronic equipment

Abstract: The present invention relates to a function unit for electronic equipment, comprising a centre plane with contact pins mounted thereon, distribution boards which can be inserted at right angles to the centre plane, from both sides thereof, and circuit boards capable of being connected in plane-parallel with the distribution boards. In accordance with the invention, the centre plane (1) is provided with groups of contact pins (2) disposed in rows and columns, the pins being isolated electrically from the centre plane and extending therethrough. The contact pins (2) are disposed along one whole edge margin of the centre plane in a terminal field (8A) which can be reached from one side of the centre plane. The distribution boards (3A, 3B) along the edge margin which faces towards the centre plane are provided with a contact device (4) adapted to the contact pins, whereas the opposing edge margin is provided with one or more contact devices (5) for connection of a coinciding number of circuit boards (6A, 6B). The distribution boards (3A, 3B) on the same side as the terminal field (8A) are inserted parallel with the field and on the opposite side of the centre plane are inserted perpen­ dicularly to the terminal field.

Description: TECHNICAL FIELD The present invention relates to a function unit for electronic equipment, and in particular for telecommunication equipment, comprising a centre plane which has electrical contact pins disposed thereon; distribution boards which can be fitted to the centre plane perpendicularly from both sides thereof, and circuit boards which can be connected to said distribution boards in plane-parallel therewith. PRIOR ART Normally, function units for electronic equipment and telecommunication equipment are designed so that related functions, such as selection functions and subscriber functions, are mounted on a plurality of circuit boards which are mutually connected electrically by means of a back plane mounted in a magazine and common to said circuit boards, and the requisite electrical connections are effected through the medium of conductor paths provided in the back plane. The connection between function units of mutually the same kind or of mutually different kinds is effected through the medium of conductors, such as coaxial cables and optolinks which are connected to the functional units at the front edge of the circuit boards or to separate terminal fields or panels on the back plane. An arrangement of multiple electrical circuits is disclosed in US-A-4 472 765. Since a telephone exchange of even relatively small capacity requires a large number of mutually different function units, the equipment seen as a whole has become highly space consuming and because of the numbers of cables or wires required between the various function units, it is difficult to obtain an overall view of the eqipment. This makes it difficult to carry out repair work and maintenance. The necessary peripheral equipment, such as cooling equipment and the like, has resulted in additional space requirements with accompanying limitations to the space available for the telecommunication equipment. As before mentioned, the various circuit boards mounted in a magazine intended herefor have been mutually connected by conductor paths in the back plane. The progressively increasing miniaturization of components with the subsequent possibility of densely packing the circuit boards has, to some extent, alleviated the aforesaid drawbacks relating to space requirements. At the same time, however, the need of conductor paths in the back plane for making the necessary connections has increased. It has not been possible, however, to fulfil this requirement completely, since the space available in the back plane between the requisite contact pins has not been sufficiently large for the purpose. DESCRIPTION OF THE INVENTION The object of the present invention is to provide a function unit for electronic equipment, particularly telecommunication equipment, which will avoid the aforementioned drawbacks. This object is achieved by replacing the conventional back plane with a centre plane having disposed thereon in rows and columns groups of through-passing electrical contact pins to which a plurality of circuit boards can be connected from both sides of the plane. The circuit boards, however, are not connected directly to the centre plane, but through the intermediary of intermediate distribution boards, each of which distribution boards extends across the whole of the centre plane and is common to several mutually adjacent circuit boards. The requisite connections between the circuit boards are effected with the aid of conductor paths in the distribution boards. Furthermore, the distribution boards, and thus also associated circuit boards, on one side of the centre plane are fitted perpendicularly to the distribution boards on the other side of said centre plane, thereby enabling all circuit boards to be connected to one another without requiring the provision of additional conductor paths. Finally, a terminal field is arranged along at least one edge of the centre plane so as to be accessible from one side of the plane for incoming and outgoing signal lines to other function units, current supply cables and the like. A second terminal field is preferably arranged along a second edge on the centre plane, perpendicularly to the first mentioned edge on said plane, this second terminal field being accessible from the opposite side of the centre plane. Preferably, electrically conductive plates are attached to the centre plane in parallel with and externally of the distribution boards and associated circuit boards, these plates functioning as EMC-screens for the function unit. The corners of the plates distal from the centre plane are mutually connected by means of plate-connecting profiles. An advantage is afforded when guide bars are mounted between the centre plane and the connection profiles for guiding the distribution boards when fitting said boards to said plane, and when further guide bars are mounted on the distribution boards for guiding the circuit boards when fitting the same. The centre plane preferably consists of a sheet of electrically conductive material and the electrical contact pins passing through the centre plane are electrically isolated from the plate by means of insulating sleeves. Earth pins which are in electrically conductive contact with the centre plane may be disposed betwen the groups of contact pins. These earth pins extend from the centre plane and into the electrical contact device on corresponding distribution boards. A function unit constructed in accordance with the invention provides several advantages. One important advantage is that the mutually perpendicular distribution boards enable all circuit boards in the function unit to be connected together in a simple and purposeful manner, without requiring the provision of additional conductors. The conductors required for electrical supply and signal transmission can be connected readily to the function unit in the terminal field with a clear view of the equipment. Another advantage is that possible changes in the mutual connections between the circuit boards can be effected readily by an exchange of distribution board. Replacement of circuit boards which are found to be faulty or for other reasons is also made easier, since each distribution board is common to several circuit boards, and hence each of the circuit boards may be constructed for a particular purpose, i.e. given the form of a special duty board, more readily than has hitherto been possible, while at the same time being smaller in size and therefore more readily handled. The arrangement of a further terminal field on the side of the centre plane opposite to the first mentioned terminal field provides the advantage of enabling the function units to be connected more readily to other function units in an easily viewed manner, so that incoming signal lines can be connected on the front side and outgoing signal lines connected to the rear side, for instance. A further advantage is that the plates which function as EMC-screens function, together with the plate-connecting profiles, form a magazine for housing distribution boards and circuit boards. The guide bars therewith facilitate insertion of the boards into the magazine. When the centre plane is made of an electrically conductive material, the advantage is afforded that the centre plane will function as an EMC-screen between the distribution boards and the circuit boards on respective sides of the centre plane. One side of the centre plane can therefore be configured as a high voltage environment and the other side as a low voltage environment, in a purposeful manner. Earth pins can be readily disposed between the groups of electrical contact pins at the intersection points between the distribution boards and will function as additional screens between the mutually different environments. Further advantages afforded by the function unit will be evident from the following description of a preferred exemplifying embodiment of the invention described with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective, exploded view of the principle construction of an inventive function unit. Figure 2 illustrates in perspective part of the arrangement of electrical contact pins or connector pins in the centre plane and associated distribution board. BEST MODE OF CARRYING OUT THE INVENTION Figure 1 illustrates the principle construction of the function unit. The function unit includes a centre plane 1 which has mounted thereon a large number of electrical contact pins 2 which are isolated electrically from the centre plane and which extend through said plane. The contact pins 2 are distributed over substantially the whole surface area of the centre plane and are arranged groupwise in rows and columns, said groups of contact pins being located at the intersection points between distribution boards 3A and 3B on the front side and rear side of the centre plane respectively. The contact-pin arrangement will be described in more detail below with reference to Figure 2. As beforementioned, the contact pins 2 are arranged over substantially the whole of the surface area of said centre plane 1, and hence there is no room on the centre plane for conductor paths. Conductor paths, required to enable all conceivable electrical connections to be made between the various components of the function unit, are mounted on the aforesaid distribution boards 3A and 3B. The distribution boards 3A on one side of the centre plane 1, i.e. the front side as seen in Figure 1, are therewith fitted perpendicularly to the centre plane and extend along the whole of said centre plane in the vertical direction, as seen in Figure 1, where for the sake of clarity only one distribution board is shown. Similar distribution boards 3B are mounted on the opposite side of the centre plane 1, i.e. on the rear side of said plane as seen in the Figure. The distribution boards 3B also extend over the whole of the centre plane, but distinct to the distribution boards 3A, horizontally placed. Both the distribution boards 3A and the distribution boards 3B are provided with electrical contact devices 4 which extend along the whole of one side of the distribution boards and can be connected to contact pins on the centre plane 1. Each distribution board 3A can, in this way, be connected to one column of groupwise arranged contact pins 2, whereas each distribution board 3B can be connected to a row of groupwise arranged contact pins. The distribution boards 3A and 3B are provided with a plurality of electrical contact devices 5, for instance four devices, along the side thereof opposite to the side provided with the contact devices 4, as illustrated in the Figure. Circuit boards 6A on the front side of the centre plane and circuit boards 6B on the rear side of said plane can be connected to the distribution boards via these contact devices 5. Thus, in the case of the illustrated embodiment, four circuit boards 6A or 6B can be connected to each distribution board. Each circuit board is therewith provided with a contact device 7 which is adapted to the contact device 5. The arrangement is such that the circuit boards 6A and 6B can be connected in parallel planes to corresponding distribution boards 3A and 3B respectively. In order to enable the function unit to be connected to other function units or to other equipment, a terminal field 8A is provided on the front side of the centre plane 1, along one edge margin thereof. The terminal field 8A extends parallel with the distribution boards 3A on this side of the centre plane and is a field where no distribution board is connected to the centre plane. However, on the rear side of the centre plane distribution boards 3B also extend over the contact pins within this region. The terminal field 8A, which can thus be reached from the front side of the plane, is used for incoming and outgoing signal lines, current supply lines and the like. If necessary, a further terminal field 8B can be provided on the rear side of the centre plane 1, this terminal field 8B extending perpendicularly to the terminal field 8A. The terminal field 8B has been obtained in a manner similar to the terminal field 8A, i.e. by omitting a number of distribution boards 3B. Figure 1 also illustrates two pairs of electrically conductive plates 9A and 9B respectively, which function as EMC-screens for the distribution boards and circuit boards. The plates 9A on the front side of the centre plane therewith extend parallel to and externally of the distribution boards 3A and the circuit boards 6A and have the same geometric extension as said boards. Correspondingly, the plates 9B on the rear side of the central plane are arranged parallel with and externally of the distribution boards 3B and the circuit boards 6B and have the same extension as said boards. Both the plates 9A and the plates 9B are screwed firmly to the centre plane in some appropriate manner and the corners of the plates distal from the centre plane are joined together by means of plate-connecting profiles 10. Thus, it can be said that the plates 9A and 9B respectively, together with the centre plane 1, form two magazines for the distribution boards 3A and the circuit boards 6A and for the distribution boards 3B and the circuit boards 6B respectively. In order to facilitate insertion of the distribution boards 3A and 3B respectively, guide bars 11 are disposed between the centre plane 1 and the connecting profiles 10, said guide bars 11 thus functioning as guides when fitting respective distribution boards. The distribution boards are also provided with guide bars 12 between and externally of the contact devices 5 respectively, in order to guide insertion of the circuit boards in a corresponding manner. Illustrated in figure 2 is part of the centre plane 1 and its contact pins 2. For the sake of illustration, only a few contact pins 2 have been drawn in the figure. The figure also shows the manner in which a number of distribution boards 3A and 3B respectively are connected to the centre plane. The figure shows that the contact pins 2 extend through the centre plane 1 and that these pins can be connected to respective contact devices 4 on the distribution boards 3A and 3B. In the case of the illustrated embodiment, the centre plane 1 consists of a plate made of electrically conductive material, such as aluminium. In order to electrically isolate the contact pins 2 from the centre plane, the pins must be insulated therefrom, which is achieved with the aid of insulating sleeves 14 which embrace respective contact pins 2. When the centre plane is made of an electrically conductive material, earth pins 13 can be arranged between the contact pins 2. The earth pins 13 are anchored in the centre plane 1 in an appropriate manner and extend from said plane solely in one direction and are so arranged that the earth pins will extend in to corresponding contact devices 4 on opposite sides externally of the groups of contact pins 2. Only a few contact pins 2 have been shown in figure 2 for the sake of clarity. Furthermore, the various groups are shown to contain different numbers of pins. In reality, each group will however contain an equal number of contact pins 2, for instance three times three pins. In the case of the illustrated embodiment, the number of earth pins 13 will be three pins above and beneath each group of contact pins 2 on the front side of the centre plane and correspondingly three pins to the left and to the right of each group of contact pins 2 on the rear side of the plane. It will be understood, that the number of contact pins 2 and corresponding number of earth pins 13 within the groups may be different to that recited above. It will therefore be understood that the invention is not restricted to the aforedescribed and the illustrated embodiments, but that modifications can be made within the scope of the following claims.

Claims: A function unit for electronic equipment, particularly for telecommunication equipment, comprising a centre plane (1) with electrical contact pins (2) mounted thereon, distribution boards (3A; 3B) insertable at right angles to the centre plane from both sides thereof, and circuit boards connectable to the distribution boards in plane-parallel therewith, where the centre plane (1) is provided substantially over the whole of its surface area with electrical contact pins (2) which are arranged groupwise in rows and columns and which extend through said centre plane and are isolated electrically therefrom, so that said contact pins (2) are disposed along one edge of the centre plane (1) in a terminal field (8A) which extends along the whole of said edge and which is accessible from one side of the centre plane (1), said field (8A) being intended for the connection of incoming and outgoing signal lines, current supply lines and the like; each distribution board (3A, 3B) provided along the edge thereof which faces towards said centre plane (1) with an electrical contact device (4) connectable to said contact pins (2), and along the opposite edge with one or more electrical contact devices (5) for connection to a coinciding number of circuit boards (6A, 6B); each circuit board provided with a corresponding electrical contact device (7); the distribution boards (3A, 3B) extending transversely across the whole of the centre plane (1) and fitted on the same side as the terminal field (8A) parallel therewith and, on the opposite side of said centre plane (1), fitted perpendicularly to the terminal field (8A). A function unit according to Claim 1, wherein the contact pins (2) along one edge of the centre plane (1) perpendicularly to said first edge are arranged in a second terminal field (8B) which extends perpendicularly to said first terminal field (8A) along the whole of said edge and which is accessible from the opposite side of the centre plane (1). A function unit according to Claim 1 or 2, wherein plates (9A, 9B) made of electrically conductive material and functioning as EMC-screens are mounted on the centre plane (1) parallel with and externally of the distribution (3A, 3B) and circuit boards (6A, 6B) and have the same extension as said boards, the corners of said plates distal from the centre plane being connected to one another by means of plate-connecting profiles (10). A function unit according to Claim 3, wherein guide bars (11) are mounted between the centre plane (1) and the connecting profiles (10) and function as guide means when fitting said distribution boards (3A; 3B); and in that further guide bars (12) are mounted on and extend outwardly from the distribution boards (3A, 3B) between and externally of the contact devices (5) and function as guide means when fitting the circuit boards (6A, 6B). A function unit according to any one of Claims 1-4, wherein the centre plane (1) comprises a plate of electrically conductive material; and in that each of the contact pins (2) passing through the plate is isolated electrically from said plate by means of a respective surrounding, insulating sleeve (14). A function unit according to Claim 5, wherein earth pins (13) are mounted on the centre plane in electrically conductive contact with said plane between the groups of contact pins (2), said earth pins (13) extending out from the centre plane and into the contact device (4) on corresponding distribution boards (3A, 3B).

Inventors: ROOS STURE GOESTA, ROOS, STURE GOESTA, Roos, Sture Gösta
Applicants: ERICSSON TELEFON AB L M, TELEFONAKTIEBOLAGET L M ERICSSON
Application year: 1990
Main classification: H05K7
IPC codes: H04Q1, H05K1, H05K7