GB2237146A - A steering column switch - Google Patents

Abstract

A switch for a steering column comprises a plastics moulded circuit board body 11 (also Fig 3) in a housing 10 and provided with notches 12, 13, 14, 15 into one of which a spring biassed electrically conducting plunger 18 (also Fig 2) located at the end of a movable arm 17, is selectively moved. Circuit board body 11 has two electrically conducting layers (20, 21) exposed at the surfaces of notches 12, 13, 14, 15 so that plunger 18 provides electrical contact between layers (20, 21) when held in a notch. The layers associated with each notch are connected via tracks (22) in the printed circuit board 11 to connection terminals (22) for electrically operated ancillaries such as a windscreen wiper or washer, or trafficators. A tiltable pivotting fixing may be provided, as may further conducting layers above/below layers (20, 21). A strap 16 may be secured to housing 10 for gripping a steering column. <IMAGE>

Description

SWITCH The invention relates to switches.

The invention relates particularly although not exclusively to vehicle steering column selector switches having manually movable arms which are normally movable in two planes to operate different ancillaries. For example, such a switch can be arranged to control a windscreen washer by movement in one plane and a wiper motor at different selected speeds by stepped movement in another plane. Conventionally, the movement is suitably spring biassed and selected stepped locations held by using a spring loaded plunger or ball bearing urged into a notch, recess or the like. Electrical circuits are completed by contacts closed directly or indirectly by intermediate parts of the arm touching or urging switchable electrical contacts to open and to close according to the position of the arm relative to the steering column.By way of illustration an indexing bolt is pressed against a locking cam 50 in USA Patent Specification 4678875 and a catch ball 23 is resilient held in one of three catch recesses 24, 25 or 26 in UK Patent Specification 2084805.

The object of the present invention is to provide a simpler form of such switches.

According to the present invention a steering column selector switch or the like comprises a movable arm supporting a biassed electrically conductive plunger for location in a number of selected generally side-by-side notches, and a plastics moulded circuit board body formed to provide the notches and incorporating two or more discrete conductive layers and/or tracks of conductive material in the body leading to respective connection terminals and which are exposed at the notch surfaces for contacting by the plunger.

The connection terminals may be contacted by respective leads which extend to the outer surface of a shell for connection to external wires by soldering or otherwise which shell at least partically surrounds the circuit board body.

A steering column selector switch according to the invention will now be described by way of example with reference to the accompanying schematic drawings in which: Fig. 1 is a plan view of the switch; Fig. 2 is a sectional side view of a part of the switch; and Fig. 3 is an isometric view of another part of the switch.

Referring to the drawings, in Figure 1 a steering column switch has a housing 10 in which is mounted a moulded plastics circuit board body 11 providing four notches 12 to 15. A strap 16 is secured to the end of the housing 10 which in use surrounds and grips a steering column (not shown). A manually operable arm 17 is pivotably mounted in the housing 10 and carries a spring biassed electrically conductive plunger 18 (seen in more detail in Fig. 2) which is urged by a spring towards the body 11 and fits selectively into the notches 12 to 15.

In Figure 3, the body 17 which consists of a three-dimensional moulded circuit body has two discrete conductive layers 20 and 21 formed within the body. Connecting tracks 22 are provided which are effectively let into the outer surface of the body leading via a printed circuit arrangement to six connections 23. As the arm 17 moves about its pivot, the plunger 18 moves to lie and be held in the respective of the notches 12 to 15 where the plunger completes different connections between the upper and the lower layers 20 and 21 to effectively electrically connect between one or more pairs of the connections 23. As a result in practice, for example, relays electrically connected to the connections cause the ancillaries to be energised, such as the windscreen wiper motor, washer, trafficators and so on.

The described selector switch has the advantage over similar prior art switches in that mechanical selector mechanisms or the so-called "locking cams" or "catch recesses" are provided together with the electrical contacts in the form of a single printed body. In the prior art, the mechanical selector mechanism is one part of the switch and the electrical switching is provided by extra contacts and levers or by separately mounted micro-switches contacted intermediate the length of the arm.

Embodiments of the invention include selector switches for other applications but where otherwise normally a mechanical selector mechanism was formerly used in combination with separate electrical switching parts. The embodiments of the invention combine the mechanical notches, recesses and the like with electrical conductive layers and tracks formed in a composite plastics body so that the electrical switching can be carried out as well as and while the plunger lodges in selected ones of the notches. In this manner, although the described switch is movable in only one plane about its pivot, it will be appreciated that a tiltable pivoting fixing could be readily provided and further suitable contact discrete conductive layers situated in the notches 12 to 15 above and/or below the layers 20 and 21. In that case a more complex switching arrangement is provided while retaining the inventive combination of the notches providing both the respective mechanical interconnection and electrical selection at the same time.

Claims (10)

CLAIMS:

1. A steering column selector switch comprising a movable arm supporting a biassed electrically conductive plunger for location in a number of selected generally side-by-side notches, and a plastics moulded circuit board body formed to provide the notches and incorporating two or more discrete conductive layers and/or tracks of conductive material in the body leading to respective connection terminals and which are exposed at the notch surfaces for contacting by the plunger.

2. A switch as claimed in claim 1 wherein the connection terminals are contacted by respective leads provided for connection to external wires.

3. A switch as claimed in claim 1 or claim 2 wherein the circuit board body incorporates two conductive layers, exposed at the.notch surfaces so that when the plunger is held in any one notch said plunger will provide electrical connection between the two conductive layers.

4. A switch as claimed in claim 3 wherein each of the two conductive layers, exposed in any one notch, has within the circuit board a respective connecting track to form terminal pairs associated with each notch for connection to the external wires of electrically operated device(s) controlled by the switch.

5. A switch as claimed in any of the preceding claims wherein the plunger is biassed by a spring.

6. A switch as claimed in any of the preceding claims wherein the circuit board is a printed circuit board.

7. A switch as claimed in any of the preceding claims wherein the arm is manually movable about a pivot to fit in a selected notch.

8. A switch as claimed in any of the preceding claims wherein a housing is is provided which at least partly surrounds the circuit board body.

9. A switch as claimed in claim 8 wherein the housing is provided with a strap for gripping the steering column.

10. A steering column selector switch substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.