GB2212343A

GB2212343A - Electrical junction

Info

Publication number: GB2212343A
Application number: GB8726469A
Authority: GB
Inventors: Peter Elliott
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-11-12
Filing date: 1987-11-12
Publication date: 1989-07-19
Also published as: GB8726469D0

Abstract

An electrical junction, for use in an alarm system or other applications requiring interconnection of multi-core cables, comprises a printed circuit board (1), having a plurality of terminal strips (2, 3, 4) mounted thereon. The required interconnection of the individual terminals (21-26, 31-36, 41-46) of the strips (2, 3, 4) are established by conductive paths printed on the reverse side of the board (1). In the embodiment illustrated an anti-tamper micro-switch (5) is included, which is also electrically connected to the terminal strips (2, 3, 4) and which would normally be maintained closed by the lid of a casing enclosing the junction. <IMAGE>

Description

"Electrical Junctions The present invention relates to electrical junction boxes and is particularly, but not exclusively, concerned with junction boxes for the interconnection of multi-core conductors in alarm systems or the like.

A typical burglar or fire alarm system includes a number of sensors connected via a junction box to a central control board, the sensors and control board being connected to the junction box by, for example, a six core cable (two cores for the power supply, two for the alarm sensor circuit and two for an anti-tamper circuit). Conventionally, the junction box used for the interconnection of the system simply includes a number of discrete post terminals, and possibly an anti-tamper micro-switch, requiring a number of conductors to be connected to each post and hard wiring of the various parallel and serial connections between posts at the time of installation. The casing for such a box is relatively bulky and the connections are generally untidy, causing confusion and thus making errors more likely and fault-finding difficult.

It is an object of the present invention to obviate or mitigate the aforesaid disadvantages.

According to the invention, an improved electrical junction includes a printed circuit board having a plurality of connection terminals affixed thereto and having the terminals interconnected in a predetermined manner by means of conductive paths formed on the printed circuit board.

Preferably, said terminals are provided by one or more terminal strips each including a plurality of separate terminals.

One embodiment herein described, which is particularly suitable for use in alarm systems, includes a plurality of terminal strips, each having two power supply terminals and two alarm circuit terminals.

Preferably, there are also two anti-tamper terminals in each strip and an anti-tamper switch affixed to the printed circuit board.

The conductive paths on the board preferably connect the power supply terminals in parallel, the alarm circuit terminals in series (for a normally closed circuit) or in parallel (for a normally open circuit) and the anti-tamper terminals and switch in either series (normally closed) or parallel (normally open).

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a top view of an electrical junction embodying the invention; Fig. 2 is a bottom view of the conductive paths of a printed circuit board forming part of the junction of Fig. 1; and Fig. 3 is a schematic diagram illustrating the connection of a number of the junctions of Figs 1 and 2 with sensors and a control board.

Referring now to the drawings, Fig. 1 shows an electrical junction comprising a printed circuit board (PCB) 1, having three terminal strips 2, 3 and 4 and an antitamper micro-switch 5 attached thereto, the strips 2, 3 ,4 being arranged adjacent three sides of the PCB 1 and the micro-switch 5 in the centre thereof. The board 1 (which in this example might typically be 1.8"/4.6 cm square) may be provided with apertures 6 whereby it may be mounted in a casing or the like (not shown).

In this example, each of the terminal strips 2, 3 and 4 has six screw-clamp type terminals 21 to 26, 31 to 36 and 41 to 46 respectively, which, in a typical alarm system, would comprise positive and negative power supply terminals 21, 22; 31, 32; 41, 42; first and second anti-tamper terminals 23, 24; 33, 34; 43, 44; and first and second alarm circuit terminals 25, 26; 35, 36; 45; 46. Fig. 2 shows the layout of conductive paths 7 formed on the reverse side of the PCB 1 to interconnect the various terminals 21 to 26, 31 to 36 and 41 to 46 and the micro-switch terminals 51 and 52. In this case the power supply terminals 21, 22 etc. are connected in parallel and the anti-tamper and alarm circuit terminals 23, 24; 25, 26 etc. in series (for "normally closed" operation). The latter may be in parallel if the circuits are to be normally open.As seen in Fig. 1, the PCB 1 may be marked adjacent each of the terminals 21 to 26, 31 to 36 and 41 to 46 to indicate their functions (positive, negative, A/T, N/C). In use, the junction may be enclosed in a casing (not shown) having a lid (not shown) which maintains micro-switch 5 closed.

Obviously, the PCB 1 may be expanded to accommodate more terminal strips if required. Alternatively, a number of junctions (which might normally be connected to two sensors and to a control board) may be connected together, as shown in Fig. 3, to suit a particular application. In the example of Fig. 3 a first junction 8 is connected to a control board 9, to a first sensor 10 and to a second junction 11, which is in turn connected to a second sensor 12. The remaining terminal strip 13 of the second junction 11 may be connected to a further sensor or junction, or, if not required, its terminals may simply be shorted or open circuited as necessary.

The example herein described is particularly suited to alarm system applications, however it will be appreciated that the invention may be advantageously applied in other situations requiring complex interconnection of multi-core cables, allowing such connections to be made neater and less bulky, and facilitating fault-finding.

Claims

1. An electrical junction including a printed circuit board having a plurality of connection terminals affixed thereto and having the terminals electrically interconnected in a predetermined manner by means of conductive paths formed on the printed circuit board.

2. An electrical junction as claimed in claim 1, wherein said terminals are provided by one or more terminal strips each including a plurality of separate terminals.

3. An electrical junction as claimed in claim 2, adapted for use in an alarm system and including a plurality of terminal strips, each having two power supply terminals and two alarm circuit terminals.

4. An electrical junction as claimed in claim 3, further including two anti-tamper terminals in each strip, and an anti-tamper switch affixed to the printed circuit board and electrically connected to the anti-tamper terminals of each strip by means of further conductive paths formed on the printed circuit board.

5. An electrical junction as claimed in claim 3 or claim 4 wherein the alarm circuit terminals of each strip are connected to one another in series, for use in a normally closed alarm circuit.

6. An electrical junction as claimed in claim 3 or claim 4 wherein the alarm circuit terminals of each strip are connected together in parallel, for use in a normally open alarm circuit.

7. An electrical junction as claimed in claim 5 or claim 6 when dependent on claim 4, wherein the anti-tamper switch and the anti-tamper terminals are connected together in series.

8. An electrical junction as claimed in claim 5 or claim 6, when dependent on claim 4, wherein the anti-tamper switch and the anti-tamper terminals are connected together in parallel.

9. An electrical junction substantially as hereinbefore described with reference to the accompanying drawings.