SE509341C2 - Telephone switch-adapted line circuit connection - Google Patents

Abstract

The invention relates to a telephone exchange adapted line circuit connection that includes a predetermined number of line circuits (10a) each capable of being allocated to a telephone exchange subscriber, wherein the line circuits are coordinated on a printed circuit board (10'), wherein the circuit board has mounted thereon discrete components in the form of subscriber-conductor resistances (70) for each of the line circuits, and wherein the resistances are dimensioned for high heat dissipation. Each of the resistances (70) is comprised of a conductor, having an adapted resistivity and resistance, being mounted to a foil (71), and the foils are related to one or more heat-absorbing surfaces for effective heat transfer to the surfaces. Said conductors (70) in said foils (71) are connected to one or more contact devices (72) adapted for coaction with corresponding contact devices on the printed circuit board (73).

Description

f- u .. 509 341 '"“ "¿å It is also previously known that each of these must be dimensioned to be able to offer a high heat dissipation and for this purpose it is required that the resistance body or unit be placed at an adapted large distance. from the surface of the circuit board and preferably in the vicinity of a housing surrounding the circuit board, so that a heat dissipation can take place via a narrow air gap to the housing.

It is also known that the line circuit resistors can have a resistance value of 2 x 250, 2 3 400 or 2 x 800 ohms depending on the selected circuit solution.

Considering the measures taken with the present invention, it can be mentioned that it is known to form a resistance body as a foil with a resistance conductor oriented as a loop. The foil can be provided with an adhesive layer for application to a heat-conducting material.

As an example of foils of this kind, reference is made to the foil that is manufactured and sold through Calesco Foil AB in Kolbäck.

The prior art also includes the contents of the following patent publications; Hs-a_5 35] 3QQ A balancing resistor and thermistor circuit for telephone circuits is shown and described here.

The said publication describes a system in which utilized line circuits must be able to withstand high transient voltages from thunder, overheating of the circuit arrangement and / or lower transient voltages from mains circuits.

The means that the said patent publication directs in order to be able to meet the specified conditions, are i.a. using a thin substrate with the front and back sides parallel in parallel, applying via a screen printing method first and second thick films, in the form of a resistive property having film, on one side of the substrate, apply via a screen-printing method third and fourth thick films, in the form of a resistive properties exhibiting film on the other side of the substrate, create conditions so that a gap is formed between the first and second and third and fourth thick film sections, as well as a very special further orientation of the thick-film sections and an interconnection thereof, with the resistance values balancing each other and a thermistor-film screen-printed in said gap and a relay arrangement, which is influenced by the heat generation.

Here, however, it is indicated that eight connection pins 14-21 are arranged to the lower part of the resistance unit 10 and that these are insertable into holes in a circuit board.

Here, a resistance-indicating device for controlling a fan, included in an air-conditioning car belonging to the system, is shown and described, by regulating the electric current to be supplied to the fan motor, in order thereby adjusting the capacity of the fan.

The device shown here comprises a plurality of resistors, with mutually different resistance values, which are connected downstream of the fan in order to be able to be cooled by the air flow forced therefrom.

The resistance device (5) comprises an air-cooling block (8), a resistance circuit (9), a support means (22) for the block (8) and a support plate (12) for the connection terminals.

The block (8) comprises a flat base part (13) and a plurality of cooling flanges (7a, 7b), integrally formed to the upper surface of the base part (13). Some heat sinks (7a) extend vertically while other heat sinks (7b) extend horizontally. 509 341 The resistance circuit (9) comprises a continuous resistor (9a) extending in zig-zag form and insulating paper (16) covering exposed surfaces of the circuit (9).

The resistance circuit (9) is kept in contact with the cooling block (8) via an insulating paper (16) and is formed via etching of a copper-nickel plate. nS-a-5 452 319 A battery-feeding resistor of film tape is shown and described here. unu IEKHISKI_2BQBLEM Taking into account the previous state of the art, as described above, it should appear as a technical problem to be able with simple means and within a specified arrangement to create such conditions that a heat dissipation from subscriber line-associated resistances shall, without any appreciable air gap, can be transferred directly to a well-adapted heat-absorbing surface, for efficient heat transfer and heat transport from the circuit board.

It must also be considered a technical problem to be able to realize the significance of and the advantages associated with allowing at least some of the abstinence-associated resistances to be physically separated from the circuit board or the circuit board.

It is also a technical problem to be able to find suitable places to apply the line circuit resistances, two for each line circuit, so that the heat transfer to heat sinks and the like is efficient, without therefore having to adversely affect the temperature of the used circuit board. .

There is also a technical problem in being able to realize the significance of allowing each of said resistors to be constituted by one or more resistance-exhibiting conductors, applied to and / or formed as a foil, and thereby in a simple manner be able to relate said foil directly to a heat-absorbing surface, separate from the pattern or circuit board.

There is then a technical problem in being able to realize the prerequisites required and the advantages associated with allowing said conductor in said set of foils to be connected to a connector, related to said heat absorbing surface, and where this connectors are adapted for collaboration with corresponding card-related connectors.

There is also a technical problem in being able to realize the advantages associated with allowing said card to be enclosed in a known manner in a divided, such as two- or three-part, metallic or metallized casing and to use a or several of the inner surfaces of the housing for attaching said foil thereto.

There is also a technical problem in being able to realize the significance of and the advantages associated with allowing a plurality of paired foils for a plurality of line circuits to be attached and related to said casing surface or surfaces and with the conductors of the foils connected to a set of contacts ballasts, where these connectors are advantageously oriented in a row, like a terminal block.

It is hereby required that the utilized printed circuit board must also be shown in a series of oriented connectors, such as a contact terminal and that the said connectors in resp. terminal block is in cooperation when said printed circuit board is placed to be covered by the housing.

There is also a technical problem in being able to realize the importance of, by means of line circuit-related resistances in the form of foils, creating an adapted heat distribution and leaving at least one surface, preferably the two opposite inner surfaces of the two parts in the housing, forming carriers. for said foils. 509 341 5 * ¿There is also a technical problem in allowing, as a complement, all or a selected proportion of said foils to be attached to one or more rack-like rails or the like, such as rails, intended to control the insertion and extension of a housing with enclosed circuit board.

There is also a technical problem in being able to dimension the surface spread of the foil in order to have an adapted resistance value and to be adapted to the number of line circuits on the printed circuit board and to provide an adapted heat transport to the housing and / or stand.

The present invention is based on a telephone exchange adapted line circuit connection, of the type indicated in the introduction, and indicates, in order to be able to solve one or more of the above-mentioned technical problems, that subscriber line associated resistors, included in said line circuit connection, should consist of one, an adapted resistance and / or resistivity, conductor, in a known manner applied to a foil, that said foil is related to and attached to a heat-absorbing surface for an efficient direct heat transfer and that said conductor in said foil is connected to a surface-related connector, adapted for a co-operation with corresponding card-related connectors.

The invention then proposes that said card should be enclosed in a divided casing, that selected foils are attached to the inner surface of the casing and / or opposite inner surfaces and that the other one or more foils may be attached to one or more rack-associated rails, intended to guide a insertion and extraction of a metallic housing with enclosed circuit board.

As proposed embodiments, it is contemplated that a plurality of foils are attached to said surface (s) and with the conductors connected to a set of connectors, oriented as a contact terminal or contact strip, wherein said connector and terminal may advantageously be oriented in a row .

It is further indicated that the printed circuit board should have a series of oriented connectors oriented as a terminal block and that said connectors are in an electrical and a mechanical interaction with each other when said printed circuit board is placed in and covered by the housing.

In addition, indicate that two opposite inner surfaces of the parts in the housing shall form carriers for said foils.

For a practical application of the present invention, each foil for a selected resistance value should be adapted with a surface spread having the dimensions 10-20 mm x 40-120 mm, with end-related exposed contact surfaces.

It is further indicated that the foil should advantageously be provided with an adhesive surface, intended for fixed interaction with said heat-absorbing surface.

H The advantages that can primarily be considered to be characteristic of a telephone exchange-adapted line circuit connection, in accordance with the present invention, are that in this way conditions have been created to be able to place subscriber line-associated resistances with high heat dissipation directly and without air gap against heat-absorbing surfaces , which consists of or is in good heat contact with heat sinks and thus offers efficient heat transport without excessive heating of the circuit arrangement of the line circuits otherwise related to a used printed circuit board with printed wiring or circuit board with discrete surface mounted components.

What can primarily be considered as characteristic of a telephone exchange-adapted line circuit connection, in accordance with the present invention, is stated in the characterizing part of the subsequent claim 1 509 341.

A presently proposed embodiment of a telephone exchange associated and adapted line circuit switching arrangement, in accordance with the present invention, will now be described in more detail with reference to the accompanying drawing, in which; figure 1 figure 2 figure 3 figure 4 figure 5 figure 6 shows in a first perspective view a cabinet adapted for a number of line circuit board-associated blocks, which exhibits the significant properties of the present invention, shows the cabinet according to figure 1 in another opposite perspective view, shows in plan view a block with a heat sink as surface magnification and where subscriber line-associated resistors are placed in a known manner on a circuit board enclosed in a housing, and enlarged side view known installation of a resistor, shows in perspective view opposite rails for receiving a block with the rails directly mounted to separate heat sinks, and with resistance-showing foils mounted to the rails, shows in exploded view a housing with enclosed circuit board and where subscriber-associated resistances are formed as foils and applied to the inner opposite surfaces of the housing, in a manner indicated for the invention and showing in perspective view a resistance-showing foil with an adhesive layer partially attached to one heat-absorbing surface. lgll 509 341 n H u With reference to Figures 1 and 2, a cabinet is thus shown there in two different perspective views, comprising e.g. a telephone exchange-associated cross-connection arrangement.

The cabinet has been assigned the reference numeral 1 and comprises a stand, with two parallel-oriented and opposite frame sides 1a, 1b and a cross-side associated side side 1c.

Furthermore, there is a further frame side 1d, from which side a number of blocks, such as the block 10, are slidable and extendable in a manner which will be described in more detail later.

Furthermore, the invention is based on the fact that each such block 10 could enclose a circuit board 10 'and such a circuit board could comprise a number, say thirty, of line circuit connections, adapted for a telephone exchange.

Figure 1 further illustrates that a number of subscriber-connected connection pins associated with the stand, coordinated to one or more connection terminals, the top of which is assigned the reference numeral 2a, are structured in rows and oriented over each other in a column 2 and that a number of telephone-related telephone exchanges line connection pins 3a, coordinated to one or more terminal blocks, are structured in rows and oriented in a column 3.

Figure 1 illustrates that each subscriber-associated terminal block 2a is oriented in a column 2 located outside said column 3 of line circuit-associated terminal blocks 3a.

The number of utilized cross-coupling conductors so-called jumpers are usually relatively large, as each connected subscriber must be in an electrical connection with its own line circuit with two physical conductors. A single such cross-coupling conductor or jumper 23 is shown in Figure 1 for simplification purposes and is attached to its pins in a manner further described in a patent application filed 9600358-7 filed today, with the same applicant, and which titled "Cross-Coupling Arrangement".

A predetermined number, illustrated in the exemplary embodiment by thirty telephone exchange-related line circuits, of a nature previously known per se, are coordinated into a block 10, which carries a printed circuit board 10 'with surface-mounted discrete components.

In a telephone exchange application, the invention requires access to a large number of subscriber-associated conductors, available to be able to be connected to a line circuit assigned to a subscriber, via a cross-connection arrangement and conductor 23.

In practical application, a utilized cross-coupling arrangement requires a plurality of such blocks, but since the other blocks can be considered identical to block 10, the following description will only cover this block.

Each block 10 has an outer divided, such as two- or three-part, casing 10c of a metal, such as aluminum, where the casing encloses a printed circuit board 10 ', whose electrical interaction with the environment, line circuit-associated connection pins and terminals 3, takes place via block-associated connection pins 10d .

The circuit board may have different functions, but the following description only covers circuit boards with line circuits.

Each of the blocks 10 is then slidably and extendably arranged along parallel rails 11, 12, which in a known manner are attached to said frame, and in particular the frame sides 1a and 1b, which are formed by cooling flanges 13, 14.

The front portion of the block 10, in the insertion direction, shows line circuit-assigned block-associated connection pins 10d, coordinated to a terminal block 10e, which pins in a fully inserted position of the block 10 are in an electrical and mechanical interaction with said telephone exchange-related connection pins, terminal block, such as terminal block 3a.

It is important that block-associated connection pins l0d must be in direct or indirect electrical contact with the connection pins for the terminal block 3 and thereby be accessible from the outside for connection to subscriber lines via jumpers 23.

Said block 10 and said rails 11, 12 are in such mechanical interaction that within the block, of components constituted therein, heat generated will be conducted over to the sides 1a, 1b of the frame and further to the cooling fins 13, 14 of the sides.

Heat-generating discrete components 10a, 10b, such as transformers, diodes, transistors, should be oriented on said printed circuit board 10 'and depending on the power development adjacent to the areas facing the rails 11, 12.

The material thickness and the thickness distribution within the housing or block are adapted for a satisfactory heat transport via the rails 11 and 12.

In this case, it is possible to select different thicknesses of the housing 10c and different lengths and widths of the rails 11, 12.

The casing thickness etc. should be chosen here so that even under a high load for shorter times, say shorter than 30 minutes, the temperature increase will be within the specified limit values.

The cover 10c is also completely closed, in order to offer effective EMC protection.

The block can also be provided with one or more surface enlargements 509 341 Vi; ¿”rings.

Such a surface enlargement could be that the edge 10 of the block 10, facing the connection terminal 10d, is provided with cooling flanges 10g 'in the manner shown in Figure 1.

Furthermore, it appears that a line 10 belonging to said block 10, connected circuit terminal 10e, must be able to cooperate with a corresponding connection terminal 10h in a further block 15, which in turn has a connection terminal 15a which is in electrical co-operation with said line circuit associated terminal 3a.

The additional block 15 may consist of a simple connection between the connecting pins in the terminals 10e and 15a or contain circuit connections and / or circuit arrangements, such as overvoltage protection.

Opposite rails 11, 12 are in a known manner directly attached to the adjacent heat sink and the legs 11a, 11b of the rail are assigned a length (300 mm) and a width (150 mm) which provides the desired heat transfer.

The vertical distance between adjacent legs 11a, 11b shall be adapted to exceed only slightly the thickness of the block 10.

Figure 1 is intended to illustrate that within a space 51 subscriber-associated cables shall be arranged and existing conductors therein shall be attached in a known manner to the rear side of the connection terminal 2a in order to thereby leave the front sides free of the required jumpers.

In the practical embodiment, adjacent blocks are oriented closer to each other than that shown in the figure.

The invention thus comprises a telephone exchange adapted line circuit connection with a predetermined number of line circuits, each of which can be assigned to a subscriber belonging to a telephone exchange, said line circuits being coordinated to a card with printed wiring 10 'or the like, to which cards are attached a number, resp. line circuit associated with discrete components 10a, 10b, each of said line circuits comprising as discrete components subscriber line associated resistors 31, 31 ', each of which is dimensioned for a high heat dissipation.

The enlarged view in Figure 3 illustrates a prior art method of applying such resistors 31, by allowing the resistance body to be located in close proximity to the housing part 10c and at an adapted large distance from the circuit board 10 'in order thereby to be able to transfer heat via a small air layer to the housing or block 10.

The present invention 31 'is based on the fact that each of said resistors 31, is to be constituted (according to Fig. 6) by a, an adapted resistivity and resistance exhibiting conductor 70, applied to a foil 71.

Said foil 71 is related directly and without air gap to a heat-absorbing surface 80, for an efficient heat transfer.

Said conductors 70 in said foil 71 are connected to a connector 72, adapted for a co-operation with corresponding card-related connectors 73.

The circuit board 10 'is, as shown in Figure 5, enclosed in a two-part metallic housing 60 and with the parts 61, 62 located on each side of the card 10' and where each of said foil 71 is attached to the interior of the parts 61 and 63. surfaces 61a, 62a.

In particular, it is indicated that a plurality of foil portions are attached to said surface and with the conductors 70 connected to a central set of connectors 72, which are oriented in a row. The card 10 'has in a centered row oriented connectors 73 and said connectors 72, 72', 73, 73 'cooperate when said card 10' is placed inside the housing 60.

Figure 5 also shows the possibility of allowing one or the two opposite inner surfaces 61a, 62a of the two parts 61, 62 in the housing to form carriers for said foils 70, 71, 70 ', 71'.

Referring to Figure 4, it is shown that one or more of said foils 71 is attachable to one or more rack-associated rails 11, 12 intended to guide a housing 10 with enclosed circuit board 10 '.

It is shown here that utilized foils are inserted in grooves 11a ', 11b' in the rail portions 11a, 11b and with a connector 72 "placed in one end portion of the rail 11 and intended to cooperate with a corresponding connector 73" attached to the printed circuit board.

A foil for an adapted resistance value should advantageously have a surface extension with the dimensions 10-20 mm x 40-120 mm with end-related contact surfaces 74, 75, where these contact surfaces 74, 75 are connected in a known manner to contact elements in the contact terminal 72.

Furthermore, the foil 71 should be provided with an adhesive surface 7la intended for a fixed interaction with said heat-absorbing surface 80.

Since the present invention provides a possibility to place heat-generating line circuit resistances quite arbitrarily, an attempt is made to place them close to the rails 11, 12 and / or the cooling fins 12, 13.

In particular, it is proposed that the resistors be placed in the rail portion 11b and here one or more foils 71 can be placed one above the other and with an adapted air gap to the housing 10 to reduce the heat transport to the housing 10 and increase towards the heat sinks 12, 13. @ 5 509 341 2 x 30 resistance films, of which only a few are shown in the figures.

Figure 4 is intended to illustrate that double foils are placed on top of each other in the rails 21a with a suitable depth for the groove 11a '.

The invention is of course not limited to the above-mentioned exemplary embodiment, but may undergo modifications within the scope of the inventive concept illustrated in the appended claims.

Claims (10)

509 341? , 6 A telephone exchange adapted line circuitry having a predetermined number of line circuits (10a), each assignable to a telephone exchange associated subscriber, said line circuits being coordinated to a card (10 ') with printed wiring or the like, to which cards a number are attached , resp. line circuit associated with discrete components, each of said line circuits comprising as discrete components formed subscriber line associated resistors (70), each of which is dimensioned for a high heat dissipation, characterized in that each of said resistors are constituted by a conductor (70) having an adapted resistivity and resistance, applied to a foil (71), said foil being related and / or attached to one or more heat-absorbing surfaces for an efficient heat transfer to said surfaces, that said conductors (70) in said foil are connected to one or more connectors (72), adapted for co-operation with corresponding card-related connectors (73), that said card (10 ') is enclosed in a split housing, to select foils are attached to the inner surface of the housing and that other selected foils are attached to one or more rack-associated U-shaped rails, intended to guide a housing with enclosed circuit board. Coupling according to claim 1, characterized in that a plurality of foils are attached to said surface and with the conductors of each foil connected to a set of connectors. Coupling according to claim 2, characterized in that the connectors are oriented in a row. Coupling according to claim 3, characterized in that the card has a series of oriented connectors and that said connectors are in interaction with each other when said Q, 509 541 card is placed in and covered by the housing. Coupling according to claim 1, characterized in that opposite inner surfaces of the parts in the housing form a carrier for said foils. Coupling according to claim 1, characterized in that resp. foil is provided with an adhesive surface, intended for a fixed interaction with said heat-absorbing surface. Coupling according to claim 1, characterized in that a number of foils are placed on a rail located above the housing. Coupling according to claim 1, characterized in that an air gap is arranged between the surface of the rail and the upper surface of the housing. Coupling according to claim 1, characterized in that a number of foils are placed on a rail located under the housing. Coupling according to claim 1, characterized in that among said foils a number are placed on top of each other.