GB2028000A - Direction indicator switch for a road vehicle - Google Patents

Abstract

A direction indicator switch for a road vehicle includes switch means (13) for actuating a hazard warning circuit which in use will energise at the same time and independently of the vehicle ignition circuit both pairs of direction indicator lights associated with the vehicle, the direction indicator switch including printed circuit means (14) for supplying, when said switch means (13) is operated, electric current from a live terminal (15) to a terminal (18) for feeding electric current to both pairs of direction indicator lights. <IMAGE>

Description

SPECIFICATION Direction indicator switch for a road vehicle This invention relates to a direction indicator switch for a road vehicle and relates in particular to an improved form of the general type of direction indicator switch which operates other electrical circuits, commonly the headlamp circuits, as well as the direction indicating circuits. At present, it is usual in a road vehicle to provide a hazard warning lights switch which is separate from the direction indicator switch. The direction indicator switch is usually mounted on the steering column of the vehicle, whilst the hazard warning lights switch is often mounted in or adjacent the dashboard of the vehicle.

Although this arrangement is satisfactory as far as driver operation of the hazard warning lights switch is concerned, the fact that this switch is separate from the direction indicator switch does present difficulties with electrical wiring harnesses and also with mounting the hazard warning lights switch and indicator lamp on the vehicle at a position remote from the other switching functions, which as stated, are on the steering column.

One way of overcoming these difficulties is to incorporate the hazard warning lights switch into the direction indicator switch, thereby resuiting in generally simpler wiring and less corrosion probiems.

In order suitably to combine the two switch functions in this way, mechanical means could be used, such as linkages and/or levers, possibly in conjunction with electrical wires. However, it is believed that with such mechanical means there would be the difficulty of providing an additional switching/lever mechanism, etc., for adding the hazard warning operation, in a previously designed direction indicator switch. Assembly difficulties would be likely to occur and any resultant switch would most likely be quite bulky as well as complicated and costly to assemble.

Accordingly it is an object of the present invention to provide a direction indicator switch for a road vehicle which includes switch means for actuating a hazard warning circuit, in a relatively simple and inexpensive, yet convenient and effective form.

According to the present invention there is provided a direction indicator switch for a road vehicle including switch means for actuating a hazard warning circuit to allow, in use, all the direction indicators associated with the vehicle to operate together and independently of the vehicle ignition circuit, said direction indicator switch including printed circuit means for supplying, when said switch means is operated, electric current, in use, from a live terminal of the direction indicator switch to a terminal which feeds electric current to respective left and right hand pairs of direction indicator lights, so as to cause simultaneous actuation of all said lights.

The use of a printed circuit offers many advantages compared to the use of mechanical means referred to earlier.

Firstly a switch employing a printed circuit has no mechanical parts, such as linkages or levers, and in particular, no additional switching/lever mechanism as envisaged necessary with said mechanical means. Accordingly the switch is relatively less bulky and also more reliable in operation. Electrical wires are of course avoided.

Secondly, there are likely to be less assembly problems due to the use of a less complicated arrangement and a switch using a printed circuit is less costly to produce than one using said mechanical means.

Thirdly, in operation, there would be a reduced mechanical load and friction on the operating mechanism e.g. knob or button, of the hazard warning lights switch, than with said mechanical means.

Fourthly, as will be apparent from the description hereinafter of a particular embodiment of the invention, the only movement occurring in the direction indicator switch employing said printed circuit, is confined to the region of the hazard warning lights switch itself even though electrical contacts of the direction indicator switch are well spaced therefrom.

As will be explained, this is possible by the use of a particular thin and flexible version of a standard printed circuit board, which can easily adapt to a step between the direction indicating and hazard warning sections of the direction indicator switch.

This invention will now be described by way of example with reference to the accompanying drawings, in which Figure 1 is a plan view of a direction indicator switch constructed in accordance with the present invention, Figure2 is a view generally in the direction of arrow A of Figure 1, Figure 3 shows a printed circuit arrangement together with switch means for actuating hazard warning lights, for use in a direction indicator switch constructed in accordance with the present invention, and Figure 4 is a circuit diagram illustrating the operation of said direction indicator switch.

Although the description hereinafter will describe a particular direction indicator switch, it will be appreciated that the invention is applicable to most, if not all, types of column mounted direction indicator switches.

Figure 1 shows one type of direction indicator switch intended to be mounted on the steering column of a road vehicle. The switch has an operating lever 10, which in use, is independently pivotable about two mutually transverse pivotal axes. The present invention is not concerned with the conventional operation of said lever to operate the direction indicators independently, or the headlamp circuits, and thus these operations will not be described any further.

The switch is made up of a body part 11 and cover 12, which are provided with respective extension portions which mate to form a location for an operating button of a switch 13 for actuating the hazard warning lights, as will be described. As will also be described, the switch 13 is in this embodiment spring loaded outwardly of the body part 11 and cover 12, and is shown in its 'off' position in full on Figure 1 and in its 'on' position in dashed lines.

The body part and cover may be made of glass filled nylon and may be ultrasonically welded together.

Turning now to Figure 3, there is shown the switch 13 in conjunction with a printed circuit arrangement 14, the foil or film wire circuits of which would have a 0.1 mm or other suitable thickness of high conductivity copper imprinted onto bonded insulated base material. The arrangement 14 would be disposed between the body part 11 and cover 12 and is thus shaped accordingly. The printed circuit board used is so called "flexi board" which is a thin and flexible form of a standard printed circuit board, and is of polyester material.

With the type of direction indicator switch described in this example, the horn is operable independently of the ignition and thus a horn terminal 15 which is provided is a live terminal.

Terminals 16, 17 respectively are for supplying electrical current to the right or left direction indicator lights of the road vehicle. In normal operation of these indicators, when the vehicle ignition is switched on, a terminal 18 is fed directly with electric current and operation of the lever 10 causes a spring biased, semi-circular shoe (not shown) to connect the printed circuit paths from the terminals 16 and 18, or alternatively 17 and 18, to operate the right hand or left hand indicators as required.

Further terminals 19,20 are provided in the arrangement and as will be described these are in electrical contact when the hazard warning switch 13 is in its 'off' position. This ensures a feed for normal direction indicators when the switch 13 is off. When the switch 13 is in its 'on' position the terminal 19 is electrically connected to the terminal 15.

The switch 13 is, as described, outwardly biased by a spring, not shown and in Figure 3 it is shown in its 'off' position. The switch 13 contains a bulb 21 with a pair of contacts 22,23 and the bulb 21 is provided with two spaced recess and projection arrangements to enable it to be firmly located in its associated channel shaped bulb holder. The contacts 22, 23 are in the form of respective trailing arms extending from the bulb holder at the bulb contact points. As can be seen from Figure 3, the contact 23 is, in the 'off' position of the switch, in electrical contact with the live terminal 15, by way of the metallic film of a printed electrical path 24. However in this position the other bulb contact 22, is out of electrical contact with any of the remaining films of the printed circuit arrangement.Each trailing arm contact 22, 23 is curved upwardly at its end, to provide fine contact with the films 28b, 24 respectively in the 'on' position of the switch 13, as will be described.

Electrical paths 25, 26, in the form of metallic films, extend in curved form from the terminals 19,20 respectively to terminate, as shown, under the region through which the switch 13 moves. Furthermore, the printed circuit board having the electrical paths 24, 25 and 26 has a second printed circuit board carrying further film paths 27,28,29 respectively overlying, but insulated from paths 24, 25 and 26 for a part of their extent. The path 27 extends from the terminal 17 to a position under said region of switch movement. Similarly the paths 28,29 extend from the terminals 18 and 16 respectively to terminate under the region of movement of the switch 13.

The path 28 is formed at its end remote from its terminal 18 with two arm-like extension portions 28a and 28b, as shown in Figure 3.

The switch 13 is provided in its body with three semi-circular contact shoes 30,31 and 32, directed towards said conducting paths 24, 25, 26, 27, 28 and 29. Each shoe is spring loaded so to engage with a different path or with different paths as the switch is moved between its 'off' and 'on' positions.

As can be seen from Figure 3, in the 'off' position of the switch 13, the shoe 30 is in contact with path 28a only. Shoe 31 contacts path 28 only and shoe 32 contacts paths 25 and 26 so as electrically to interconnect them. As stated, this electrical contact between the terminals 19 and 20 is required when the switch is off. The bulb terminal 22 is, as stated, out of contact with any of the paths.

If the switch 13 is now pressed and released, it will move to its 'on' position. As the body of the switch moves, in response to its spring biasing, more out of the body part 11 and cover 12, the bulb terminal 22 moves into electrical contact with the terminal 18 by means of its engagement with the paths 28 and 28b.

Since the bulb terminal 23 is still in contact with the path 24, and thus with the live terminal 15, current is supplied to the bulb 21 causing itto light. The top of the switch 13 is transparent and so the light is externally visible to indicate that the hazard warning lights are on.

As the switch 13 moves to its 'on' position, the shoe 30 moves so as to contact paths 28a and 29, thereby electrically connecting terminals 16 and 18, as shown for the shoe in dashed lines at 30a.

Similariy, shoe 31 moves to the position indicated by dashed lines for the shoe 31a, so as electrically to interconnect the paths 27 and 28, thereby electrically connecting terminals 17 and 18.

Lastly, shoe 32 moves to the position indicated in dashed lines as 32a, to break the connection between terminals 19 and 20, and to connect paths 24 and 25, and thus terminals 15 and 19, as required.

Terminal 19 is connected to terminals 16,17 at the right hand side of their bulbs, as viewed in Figure 4.

Thus all the indicator lights are then operating together to give the hazard warning condition, which is indicated by the bulb 21 being lit. The hazard warning system will, as described, operate independently of the vehicle ignition, since it is fed by a live terminal, in this example, the horn terminal.

The arrangement described can thus be easily incorporated into the direction indicator switch and since all the shoes 30,31 and 32, the bulb terminals 22, 23 and the push 'on' push 'off' mechanism of the switch 13 are all housed in the switch moulding, minimum complication is added to the direction indicator section of the switch.

To accommodate the switch 13, there can be a step in the body part 11 between the region in which the switch 13 moves and the remainder of the body part. As stated, the printed circuit boards can easily adapt to this step because of its flexible nature.

With the printed circuit means described, two printed circuits in the form of two layers of foil or film will generally be required. These layers can be provided, as above-described, on two flexible boards but alternatively they can be disposed in opposite faces of a single flexible board. The foils or films 24-29 can be increased in thickness under the switching region, if required, to provide more mechanical strength.

Although three slots plus three contacts are required in the hazard switch, it is believed that this disadvantage is far outweighed by not having any mechanical linkages or levers.

For effective operation good contacts are necessary. These can be obtained by forming appropriate parts of the body 11 with pressure points in the form of domes or tips. When foil is laid overthese body parts, it will touch the tops of the pressure points if pressure is applied to the foil e.g. by a rivet forming a terminal.

Further, in order to ensure that foil is not ripped off the board when contact is made therewith, all foil contacting members should have a shaped contacting portion, as described for the ends of the bulb contacts 22, 23 which are curved upwardly. Good bonding and rigidity is also necessary for the foils or films.

Claims (7)

1. A direction indicator switch for a road vehicle including switch means for actuating a hazard warning circuit to allow, in use, all the direction indicators associated with the vehicle to operate together and independently of the vehicle ignition circuit, said direction indicator switch including printed circuit means for supplying, when said switch means is operated, electric current, in use, from a live terminal of the direction indicator switch to a terminal which feeds electric current to respective left and right hand pairs of direction indicator lights, so as to cause simultaneous actuation of all said lights.

2. A direction indicator switch as claimed in Claim 1 wherein said printed circuit means is arranged in use also to supply, when said switch means is operated, electric current to a bulb which is provided in said switch means whereby said bulb will be energised to provide a signal to indicate actuation of the hazard warning lights.

3. A direction indicator switch as claimed in either of the preceding claims wherein said printed circuit means incorporates flexible printed circuit board means which extend over a step formed in a body which houses said switch, said step separating the region in which said switch means for actuating the hazard warning circuit is disposed and the remainder of the body.

4. A direction indicator switch as claimed in Claim 3 wherein said printed circuit means comprises two printed circuits which overlie each other and which are disposed on opposite faces of one flexible board comprising said flexible printed circuit board means.

5. A direction indicator switch as claimed in Claim 3 wherein said printed circuit means comprises two printed circuits which overlie each other and which are disposed on two flexible boards comprising said flexible printed circuit board means.

6. A direction indicator switch as claimed in Claim 2 wherein said bulb is provided with contacts in the form of a pair of trailing arms.

7. A direction indicator switch for a road vehicle including switch means for actuating a hazard warning circuit substantially as hereinbefore described with reference to and as shown in the accompanying drawings.