GB2257848A - Terminal block for dimmer switch - Google Patents

Abstract

An electrical terminal block (7) has a conductor lead retaining screw (11) and a connector pin (12) associated with each conductor-receiving bore (10A). The retaining screws (11) and pins (12) are parallel to one another transverse of the bores (10A) and extend on the same side of the block (7) with respect to the bores (10A). The terminal block (7) minimises the overall size of a dimmer switch module. The dimmer switch module includes a printed circuit board (5) having connected thereto a terminal block (7), a potentiometer (9) and a choke coil (6), the connection between the choke coil (6) and the printed circuit board (5) permitting positioning of the choke coil (6) either so as to be side-by-side with the circuit board (5) (fig. 6), or so that the circuit board (5) is superimposed on the choke coil (6) (fig. 7). The module shown in fig. 6 may be mounted in a British wall box. That of fig. 7 may be mounted in a continental wall box. <IMAGE>

Description

ELECTRICAL TERMINAL BLOCKS This invention relates to electrical terminal blocks, and is particularly concerned with the provision of electrical terminal blocks in dimmer switch modules.

A dimmer switch module comprises the electrical and mechanical components necessary for an electric light dimmer switch, mounted in a casing that is for installation in a wall box behind a decorative cover plate. It is necessary that the assembled module should be strong and remain electrically safe during installation, and that electrical connections to the module should be easy to make. There has to be provision for heat dissipation and yet the module has to be sufficiently small to fit into standard size wall boxes, which offer only restricted space for accommodating such components. A further problem is the significant difference in configuration between wall boxes used in the United Kingdom and those used in other European countries.

According to the present invention there is provided an electrical terminal block that is a unitary structure having parallel bores for receiving conductor leads, and a conductor lead retaining screw and a conductor pin associated with each bore, the retaining screws and pins all being parallel to one another transverse of the bores and extending on the same side of the block with respect to the bores. Such a terminal block provided in a dimmer switch module minimises the overall size of the module.

According to the present invention there is also provided, for forming a dimmer switch module, a printed circuit board having connected thereto a terminal block, a potentiometer and a choke coil, the connection between the choke coil and the printed circuit board permitting positioning of the choke coil either so as to be side-byside with the circuit board, or so that the circuit board is superimposed on the choke coil. Preferably the terminal block is a unitary structure as defined above.

The components mounted in a casing of configuration closely to envelope the components, form a dimmer switch module that is suited to wide, shallow United Kingdom rectangular wall boxes (casing enclosing printed circuit board and choke coil in side-by-side relationship) or to narrow, deep cylindrical wall boxes as used in other European countries (casing enclosing printed circuit board and choke coil in superimposed relationship).

Also the invention provides that a heat sink of the dimmer switch module is flush with the outer face of the casing of the module.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a diagrammatic perspective representation of a main body of a casing of a dimmer switch module, Figure 2 is a similar view of a heat sink of the module, Figure 3 is a similar view of a base of the casing body, Figure 4 is a side view on a considerably larger scale of a terminal block of the module, Figure 5 is an end view to the same scale as Figure 4 of the terminal block, Figure 6 is a diagrammatic sectional view of the assembled module in one configuration, and Figure 7 is a diagrammatic sectional view of the assembled module in another configuration.

Referring to the Figures, the casing main body 1 (Figure 1) and the casing base 2 (Figure 3) are moulded plastics components, the body 1 having lugs 3 that snap into cutouts 4 in the base 2 in order to assemble the casing. As so assembled the casing 1/2 contains, as shown in Figures 5 and 6, a printed circuit board 5, a choke coil 6, a terminal block 7, a heat sink 8 and a potentiometer 9, an operating knob 9A of which is outside the casing 1/2. As will be explained below, Figures 6 and 7 show the same components 5 to 10, but in two different arrangements.

As shown best in Figures 4 and 5, the terminal block 7 consists of a unitary structure that is a moulded plastics body 8 containing, in the particular form shown, three separate electrically conductive blocks 9 electrically insulated from one another by the material of the body 8. Through bores 10, one in each block 9, are parallel to one another and are all closed at common ends by the material of the body 8. At their common other ends the bores 10 are open for the reception of conductor leads. A conductor lead retaining screw 11 is screwed into a tapped hole in each block 9.

At right angles to the axis of the bore 10 in each block 9 a connector pin 12 extends from the block 9 out of the body 8. The pin 12 of each block is parallel to the lead retaining screw 11 of the block with these two components extending in the same direction from the block. Each pin 12 thus extends at right angles to the end of a conductor lead that is held in the associated block 9 by the screw 11 of the block.

The body 8 has two support posts 13 that extend, parallel to the pins 12, in the same direction as the pins 12 from the body 8.

The terminal block 7 is mounted on the printed circuit board 5 (Figures 6 and 7) with the pins 12 engaged in holes in the circuit board and soldered to connections on the board, the posts 13 abutting the circuit board 5 to locate the block 7 above the board 5. As the terminal block 7 is a unitary structure it is thus achieved that three electrical terminals are added to the printed circuit board 5 in one operation. With the printed circuit board 5 mounted in the casing 1/2 (or 1'/2') as shown in Figures 6 and 7, conductor leads can be passed through a cutout 14 in the side of the casing main body 1 (or 1') to be entered into the bores 10. Access can be gained to the heads of the screws 11, for securing the leads, via holes 15 in the casing base 2 and holes 16 in the printed circuit board 5.Having the connector pins 12 extending from the blocks 9 parallel to and in the same direction as the retaining screws 11, and at right angles to the bores 10, gives the terminal block 7 as a whole a compact configuration so as to minimise the space occupied thereby within the casing 1/2 (or 1'/2').

The heat sink 8, as shown best in Figure 2, is of aluminium or other good heat conducting material and consists of a plate portion17 of rectangular form with each corner cut away. Upright flanges 18 and 19 extend from two parallel edges of the plate portion 17, the cut away corners determining that at each end each flange has a portion 18A or 19A that projects beyond the edge of the plate portion.

The main body 1 (or 1') of the casing has a hexagonal aperture 20 (Figure 1) which receives the plate portion 17 of the heat sink 8 so that the outer face of the heat sink is flush with the outer face of the casing body, the heat sink being retained in the casing by the engagement of the projecting flange portions 18A and 19A under the wall of the casing body.

In the assembled module (Figure 6 or 7) the operating knob 9A of the potentiometer 9 extends through a hole 21 in the heat sink plate portion 17. The potentiometer 9 is of suitable construction to serve in a dimmer switch module, as are the printed circuit board 5 and the choke coil 6, and these components will not be further described, except to say that the leads (not shown) connecting the coil 6 to the printed circuit board 5 are of sufficient length to enable the coil 6 to be positioned either side-by-side with the printed circuit board 5 as shown in Figure 6, or so that the printed circuit board is superimposed on the choke coil so that the coil is behind the printed circuit board 5 with respect to the potentiometer 9, as shown in Figure 7.

The configuration shown in Figure 6 is suited to standard size wall boxes as used in the United Kingdom. In this configuration the casing 1/2 is of the configuration shown in Figures 1 and 2, that is it is shallow in the direction from front to back but elongated transversely of the front to back direction.

As compared with the wide but shallow rectangular wall boxes used in the United Kingdom, wall boxes used in other European countries are narrower and deeper cylindrical boxes and the configuration shown in Figure 7 is suited to such boxes. It is to be noted that the module of Figure 7 utilises the same components 5 to 10 as the module of Figure 6 in a casing 1'/2' of different configuration (but otherwise constructed as the casing 1/2 of Figure 6), the only other change being the positioning of the choke coil 6 behind the printed circuit board 5. The module thus produced is narrower but deeper than the module of Figure 6. Selection of the position of the choke coil 6 is easily achieved as (as indicated above) the coil is connected to the printed circuit board 5 by leads sufficiently long to permit movement of the coil from one position to the other.

In both configurations (Figures 6 and 7) the provision of the heat sink surface flush with the outer surface of the casing body enables the heat sink to be in contact with a cover plate of the wall box in which the module is fitted so that heat can be further dissipated via the cover plate.

Claims (11)

1. An electrical terminal block that is a unitary structure having parallel bores for receiving conductor leads, and a conductor lead retaining screw and a connector pin associated with each bore, the retaining screws and pins all being parallel to one another transverse of the bores and extending on the same side of the block with respect to the bores.

2. An electrical terminal block substantially as hereinbefore described with reference to Figures 4 and 5 of the accompanying drawings.

3. For forming a dimmer switch module, a printed circuit board having connected thereto a terminal block, a potentiometer and a choke coil, the connection between the choke coil and the printed circuit board permitting positioning of the choke coil either so as to be side-byside with the circuit board, or so that the circuit board is superimposed on the choke coil.

4. For forming a dimmer switch module, a printed circuit board and components connected thereto as claimed in claim 3, wherein the terminal block is as claimed in claim 1 or 2.

5. For forming a dimmer switch module, a printed circuit board having connected thereto a terminal block, a potentiometer and a choke coil, substantially as hereinbefore described with reference to the accompanying drawings.

6. A dimmer switch module comprising a casing closely enveloping the printed circuit board and components connected thereto as claimed in claim 3, 4 or 5.

7. A dimmer switch module as claimed in claim 5, where the casing comprises a casing main body and a casing base secured to one another by lugs carried by one and snapped into engagement with the other.

8. A dimmer switch module as claimed in claim 6 or 7 and further comprising a heat sink, a plate portion of which is received in an aperture in the casing main body flush with the outer surface of this main body.

9. A dimmer switch module as claimed in claim 6, 7 or 8, wherein the casing is shallow in the direction from front to back but elongated transversely of the front to back direction to suit shallow rectangular electrical fitment wall boxes, the coil being positioned side-byside with the printed circuit board in the casing.

10. A dimmer switch module as claimed in claim 6, 7 or 8, wherein the casing is deep in the direction from front to back but narrow transversely of the front to back direction to suit narrow, deep, cylindrical electrical fitment wall boxes, the coil being positioned behind the printed circuit board.

11. A dimmer switch module substantially as hereinbefore described with reference to Figure 6 or Figure 7 of the accompanying drawings.