Background A major problem for urban cyclists is having someone in a stationary car suddenly open a car door in their path. This is referred to as being "doored". The bicycle rider may collide with the car door or swerve out further onto the road to be hit by another vehicle, often with serious consequences. This leads to many serious injuries and fatalities.

Modern vehicles with tinted windows are hard to see into, so it is difficult for a cyclist to anticipate when a door may be opened in front of them. Headrests in the vehicles exacerbate this problem. To avoid this, bicycle commuters need to keep a watchful eye on parked cars as well as the flow of traffic and preferably keep at least a door's distance between the cyclist and parked cars. However this often requires occupying a traffic lane which would otherwise be available for passing motor vehicles. Although this is legal, it can lead to frustration from motorists, and even aggressive behavior, because they do not understand why the cyclist is not riding closer to the parked vehicles.

While there have been campaigns to educate motorists to check behind before they open their door, this has had very little effect. While systems have been proposed to alert a cyclist when a car door in front of them starts to open, that is often too late for the cyclist to take effective avoidance action. What is required is a means by which an approaching cyclist can be alerted that a car door in front of them is about to be opened before the door is actually opened.

An aim of the present invention is to provide a warning system which addresses this need.

Summary of Invention

Accordingly, in one aspect the invention provides a method of providing a warning that a door on a side of a motor vehicle may be about to swing open, said method comprising:

- detecting a change in status of a component of said vehicle which indicates an increased likelihood of said door being swung open;

- in response to said detection, initiating the flashing of a warning light external of the vehicle on said side of the vehicle;

- causing said light to flash in a different manner to that which turn indicators on the vehicle flash in normal use; and

- maintaining said flashing for a period in the range 2 to 15 seconds and then stopping said flashing.

Preferably said detection of a change in status comprises detecting when a seat belt buckle is being released for an occupant of said vehicle adjacent said door.

Said detection of a change in status may comprise detecting when a latch on said door is being released from inside said vehicle.

Said detection of a change in status may comprise detecting when an ignition key is being removed from its respective lock in the vehicle. Said detection of a change in status may comprise detecting when a parking brake is being activated on said vehicle. Said detection of a change in status may comprise detecting when a parking lock is being engaged in the transmission of the vehicle.

Preferably said warning light is positioned on or adjacent said door.

Preferably said warning light is caused to flash at a frequency at least twice that at which turn indicators on said vehicle flash in normal use.

Said warning light may be caused to flash in a different colour to that which said turn indicators flash in normal use.

Preferably said warning light is incorporated within a housing for an external rear view mirror. Preferably said warning light comprises at least part of a turn indicator luminaire. Brief Description of Drawings

In order that the invention may be more fully understood there will now be described, by way of example only, preferred embodiments and other elements of the invention with reference to the accompanying drawings where:

Figure 1 is a view of an automobile being a motor vehicle incorporating or facilitating the present invention;

Figure 2 is a view from within the automobile shown in Figure 1 ; and

Figure 3 is a view of the driver's seat of the vehicle in Figure 1 with the driver rendered invisible.

Description of Embodiments of the Present Invention The motor vehicle 10 shown in the Figures has a cabin portion 12 containing a driver's seat 14, a steering wheel 16, an instrument panel 18, a lock 19 for an ignition key, an automatic transmission selector handle 20, a handbrake lever 22 and a seatbelt assembly for the driver's seat 14. The seatbelt assembly comprises a webbing belt 26, onto which is threaded a tongue portion 24, and a housing portion 30 which is securely attached to the vehicle's floor and into which the tongue portion 24 slides where it locks in order to restrain the driver in the event of a collision. The tongue 24 and housing 30 together form the seat belt buckle 31.

The driver's door 32 has an internal door latch release lever 34 and an external rear view mirror assembly 36 attached adjacent the leading edge 38 of the door. The mirror assembly 36 comprises an adjustable mirror portion 40 mounted within a contoured housing 42. The housing 42 also incorporates on its distal end a turn indicator luminaire 44 which flashes in unison with the respective front turn indicator 46 and rear turn indicator 48. The passenger door has an external rear view mirror assembly (not visible in the Figures) similar to the mirror assembly 36. Although the motor vehicle 10 illustrated is left hand drive, it will be understood that a mirror image arrangement is applicable for a right hand drive vehicle.

There are five actions which a driver of a motor vehicle usually performs after parking but before swinging open the vehicle door to alight from the vehicle. These are, in their commonly performed sequence:

1. If the vehicle has an automatic gearbox, move the transmission selector 20 into the "Park" position.

2. Apply the parking brake by pulling the lever 22.

3. Release the seat belt buckle 31.

4. Remove the ignition key from the lock 19

5. Release the door latch 34.

The order of these actions may vary from person to person and from vehicle to vehicle, and some of the actions may not occur in some vehicles. However releasing the seat belt buckle and releasing the door latch are probably the most universal. Releasing the door latch is usually the last of these actions before swinging the door open and the time between releasing the door latch and swinging the door open is usually very short. Although triggering a warning to a cyclist when the door latch is released could provide a brief warning period, a longer warning would be preferable.

Commonly one of the last acts a driver or passenger does before opening a door is to release their seat belt. Many seat belt buckle assemblies on modern motor vehicles have some sort of electrical switch or connection whereby the buckle's status may be determined and used by a controller which signals the vehicle's information display system to indicate a warning to the vehicle's occupant(s) when a seat belt is not buckled up. As shown in Figure 2 the instrument panel 18 in the vehicle 10 carries a multi-seat alerting light array 21 which indicates such a warning if any seat is occupied while the respective seat belt is not fastened. In the vehicle 10 that electrical switch or connection in each seat belt buckle 31 is utilized in order to detect that the seat belt buckle is being released and thus the adjacent door is likely to be opened soon after.

Thus when a seat occupant unclips their seat belt assembly 24, this is detected by a switch or sensor in the seat belt buckle housing 30. The detection signal is sent to the electronic controller within the vehicle's electronic management system which in turn activates a sequence of warning light flashes to warn any cyclist approaching the vehicle. The flashes are emitted from the mirror-mounted luminaire 44, the front turn indicator 46 and the rear turn indicator 48 on the relevant side of the vehicle. The flashing continues for a set period of between 2 to 15 seconds, and preferably for about 9 seconds. Preferably the flashes are at a frequency of about 4 or 5 per second. In this way the flashing is faster and thus clearly distinguishable from the conventional flashing of turn indicators, the frequency of which typically falls within the range of 1 to 2 flashes per second. It typically takes a person 2 to 4 seconds from releasing their seat belt until they commence pushing their door open. Whilst this may not give a cyclist who is very close to the vehicle much warning time before potential impact, it is better than no warning at all and provides some time for the cyclist to take evasive or protective action. Cyclists who are further back could use the additional 2 to 4 seconds to avoid a collision. It is now common for external rear view mirror housings on each side of the vehicle to incorporate a turn indicator luminaire. The preferred embodiment of the present invention uses those luminaires as a means by which the flashing light is provided to warn the cyclist. It is also envisaged that the front and rear turn indicator lights on the respective side at the front and rear corners of the vehicle are also flashed in unison with the warning light on the respective rear view mirror assembly.

Alternatively only the light in the mirror housing may be activated. In this situation the warning light in the mirror housing would be flashed independently of the indicator lights on the front and rear corners of the vehicle. Such flashing of only the light in the mirror housing would provide an additional visual indication that a door may be opening rather than the whole vehicle turning/pulling out.

Sometimes before alighting from the vehicle, a person may remain seated in the vehicle for longer than the 9 seconds that the warning light flashes. To allow for this a detection signal is sent to the controller when the ignition key is removed from its lock within the vehicle and this triggers commencement or a re-initiation of the 9 second duration that the warning light flashes.

As a third means for detecting a change of status, a detector in the door latch mechanism detects when the door latch lever 34 is released and this triggers commencement or a re-initiation of the 9 second period of flashing. By having the detector in the latch mechanism the resultant signal to the controller occurs before the door starts to swing open, so providing a little additional warning time than a situation where outward movement of the door is required in order to activate the status detector. As an additional optional feature, the door locking mechanism in the vehicle 10 includes a time delay feature whereby each door is restrained from being swing outwards until a predetermined period of flashing has occurred. A preferred such period would be 1 to 3 seconds. This would cause a relatively short delay to the person alighting but would provide a significant warning period for a cyclist.

As a fourth means of detecting a relevant change of status, a switch in the gearbox transmission selector 20 is activated to signal to the controller when the selector is moved into the "Park" position. This would also trigger commencement or a re- initiation of the 9 second period of flashing.

As a firth means of detecting a change of status, a switch in the parking brake activation mechanism (such as the lever 22 in Figure 2) is activated to signal to the controller that the parking brake has been applied. This would also trigger commencement or a re-initiation of the 9 second period of flashing.

The signals sent to the controller by the seat belt housing, the ignition system, the door latch assembly, the transmission selector and the parking brake mechanism are all independent of each other.

Whichever of the change of status detectors first signals the controller that a change of status has occurred, that triggers commencement of the 9 second duration for which the warning lights flash. Any subsequent detection of a change of status by any of the other detectors triggers a re-initiation of the 9 second duration.

In addition to alerting a cyclist that a door is about to open, the flashing light serves to remind the person alighting from the vehicle to check whether a cyclist is approaching. While most "dooring" incidents occur when a driver's door is opened, there are also incidents when a door on the passenger side, or a rear side door behind the driver is opened into a cycle lane. Accordingly, the present invention is preferably provided for the front passenger side door as well as for the driver's door, and more preferably for all side doors in the vehicle.

It will be understood that within this specification a description of a warning light being on the same side of the vehicle as the door being opened does not restrict the light to being on a side panel of the vehicle. The light may be on the front or rear of the vehicle and mounted towards the side concerned, much as front and rear turn indicators may be positioned. Whilst the above description includes the preferred embodiments of the invention, it is to be understood that many variations, alterations, modifications and/or additions may be introduced into the constructions and arrangements of parts previously described without departing from the essential features or the spirit or ambit of the invention.

For example the flashing warning lights could use different light emitters than those used for turn indication, although they may be housed in the same housing. This would permit the warning lights to be a different colour to those of the turn indicators. It will be also understood that where the word "comprise", and variations such as "comprises" and "comprising", are used in this specification, unless the context requires otherwise such use is intended to imply the inclusion of a stated feature or features but is not to be taken as excluding the presence of other feature or features. The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that such prior art forms part of the common general knowledge in Australia.