|THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:
1. An illumination device for illuminating a target object, the device including:
a mount for maintaining the body between the target object and a predetermined detection zone;
a sensor for providing a signal in response to the detection of a foreign object within the detection zone; and
a light source mounted to the body, the light source being responsive to the signal for selectively directing light toward at least a portion of the target object that faces the foreign object.
2. An illumination device according to claim 1 wherein the signal is indicative of the position of the foreign object within the predetermined detection zone.
3. An illumination device according to claim 2 wherein the signal is indicative of the distance between the sensor and the foreign object.
4. An illumination device according to claim 3 wherein at least one characteristic of the light emitted from the light source varies depending on the signal received.
5. An illumination device according to claim 4 wherein the periodicity of the light emitted from the light source increases as the distance between the sensor and the foreign object decreases.
6. An illumination device according to claim 4 or claim 5 wherein the intensity of the light emitted by the light source increases as the distance between the sensor and the foreign object decreases.
7. An illumination device according to any one of claims 3 to 6 further including
feedback means responsive to the signal to communicate to a user the distance between the sensor and the foreign object.
8. An illumination device according to claim 7 wherein the feedback means displays visual and/or audio information to the user.
9. An illumination device according to any one of the preceding claims wherein the sensor is an ultrasonic sensor.
10. An illumination device according to any one of the preceding claims wherein the light source is at least one Light Emitting Diode (LED).
11. An illumination system according to any one of the preceding claims wherein the device is at least partly powered by a battery.
12. An illumination device according to any one of the preceding claims wherein the device is adapted for mounting to a vehicle and the target object is carried by the vehicle.
13. An illumination device according to claim 12 wherein the vehicle has a forward direction of travel and the detection zone extends rearwardly and away from the vehicle.
14. An illumination device according to claim 12 or claim 13 wherein the vehicle is a bicycle having a frame, and the mount is releasably engaged with the frame.
15. An illumination device according to claim 14 wherein the mount includes a rigid arm that is releasably engagable with a portion of the bicycle adjacent the seat and which extends rearward of the rider and the target object is the rider.
16. An illumination device according to any one of claims 14 to 15 further including a second light source responsive to the signal for selectively directing light at an area underneath a rider of the bicycle or motorcycle.
17. An illumination device according to any one of claims 14 to 16 wherein the device is at least partly powered by the dynamic motion of the bicycle when the bicycle is in motion.
18. An illumination device according to claim 12 wherein the vehicle is a boat having a hull, and the mount is releasably mounted to the hull.
19. An illumination device according to claim 12 wherein the vehicle is an ultra light aircraft having a tail, and the mount is releasably mounted to the tail.
20. An illumination device according to any one of the preceding claims wherein the illumination device is adapted to project a predefined image on the target object.
21. An illumination device according to any one of the preceding claims that is portable.
22. An illumination device substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings.
FIELD OF THE INVENTION
 The present invention relates to an illumination device and in particular to an illumination device for illuminating a target object.
 Embodiments of the invention have been particularly developed as a bicycle safety light for more clearly revealing a rider of the bicycle to an approaching vehicle. While some embodiments will be described herein with particular reference to that application, it will be appreciated that the invention is not limited to such a field of use, and is applicable in broader contexts.
 Any discussion of the background art throughout the specification should in no way be considered as an admission that such art is widely known or forms part of common general knowledge in the field.
 As the use of bicycles increases, and in particular the use of bicycles on public roads, there is a heightened risk of the associated cyclists being struck by larger and/or faster vehicles that are also using those roads. This risk is exacerbated during periods of low light, such as at night time or at dawn or dusk. The risk of being struck by a vehicle also extends somewhat to motorcycles and the associated motorcyclists.
 A partial solution to the above problem is to equip a bicycle with one or more continuously illuminated or flashing lights to alert drivers of the vehicles to the presence of the bicycle. However, these lights generally do not provide an approaching driver with a good indication of the location, size, speed and direction of travel of the bicycle. Accordingly, to further reduce the risk, cyclists have also been known to make use of clothing with mounted light sources and/or reflective strips and/or high- visibility colours and/or contrasting colours. Even so, all these types of clothing at night still have a relatively subdued effect. Further, high-visibility and/or contrasting coloured clothing requires an external source of light to have any effect. Moreover, clothing having a mounted light source also requires an external power supply. SUMMARY OF THE INVENTION
 It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.
 According to the invention there is provided an illumination device for illuminating a target object, the device including:
a mount for maintaining the body between the target object and a
predetermined detection zone;
a sensor for providing a signal in response to the detection of a foreign object within the detection zone; and
a light source mounted to the body, the light source being responsive to the signal for selectively directing light toward at least a portion of the target object that faces the foreign object.
 The signal is preferably indicative of the position of the foreign object within the predetermined detection zone. More preferably the signal is indicative of the distance between the sensor and the foreign object.
 Preferably at least one characteristic of the light emitted from the light source varies depending on the signal received. In particular, the periodicity of the light emitted from the light source preferably increases as the distance between the sensor and the foreign object decreases. Further, the intensity of the light emitted by the light source preferably increases as the distance between the sensor and the foreign object decreases.
 The illumination device preferably further includes feedback means responsive to the signal to communicate to a user the distance between the sensor and the foreign object. This feedback means preferably displays visual and/or audio information to the user.
 The sensor is preferably includes an ultrasonicsensor. The light source is preferably at least one Light Emitting Diode (LED). The device is preferably at least partly powered by a battery. In other embodiments the sensor includes more than one sensing device. For example, in one such embodiment, the sensor includes two spaced apart sensor devices having respective detection zones that overlap. In other embodiments, the respective detection zones do not overlap, while in further embodiments the detection zones overlie one another. In some embodiments, the different sensing devices are responsive to different types of inputs. For example, in one embodiment, one sensor device is an ultrasonic sensor, and another sensor is a passive infra-red sensor.
 The device is preferably adapted for mounting to a vehicle and the target object is carried by the vehicle. The vehicle preferably has a forward direction of travel and the detection zone preferably extends rearwardly and away from the vehicle. The vehicle is preferably a bicycle having a frame, and the mount is preferably releasably engaged with the frame.
 The mount preferably includes a rigid arm that is releasably engagable with a portion of the bicycle adjacent the seat and which extends rearward of the rider and the target object is the rider.
 The illumination device preferably further includes a second light source responsive to the signal for selectively directing light at an area underneath a rider of the bicycle or motorcycle.
 The illumination device is preferably portable.
 In an alternative embodiment, the illumination device is preferably at least partly powered by the dynamic motion of the bicycle when the bicycle is in motion.
 In an alternative embodiment the vehicle is preferably a boat having a hull, and the mount is preferably releasably mounted to the hull.
 In another alternative embodiment the vehicle is preferably an ultra light aircraft having a tail, and the mount is preferably releasably mounted to the tail.
 In a further alternative embodiment, the illumination device is preferably adapted to project a predefined image on the target object.
 Reference throughout this specification to "one embodiment", "some embodiments" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment", "in some embodiments" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.
 As used herein, unless otherwise specified the use of the ordinal adjectives "first", "second", "third", etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.
 In the claims below and the description herein, any one of the terms comprising, comprised of or which comprises is an open term that means including at least the elements/features that follow, but not excluding others. Thus, the term comprising, when used in the claims, should not be interpreted as being limitative to the means or elements or steps listed thereafter. For example, the scope of the expression a device comprising A and B should not be limited to devices consisting only of elements A and B. Any one of the terms including or which includes or that includes as used herein is also an open term that also means including at least the elements/features that follow the term, but not excluding others. Thus, including is synonymous with and means comprising.
BRIEF DESCRIPTION OF THE DRAWINGS
 Preferred embodiments 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 the bicycle light according to the invention showing the light-sensor unit in the storage configuration;
FIG. 2 is a right side view of the bicycle light of FIG. 1;
FIG. 3 is a bottom view of the bicycle light; FIG. 4 is an inverted left side view of the bicycle light;
FIG. 5 is a top view of the bicycle light with the lid removed revealing the battery cavity;
FIG. 6 is a longitudinal cross- sectional view taken along plane B-B in FIG. 1;
FIG. 7 is a top view of the bicycle light showing the light-sensor unit in the operative configuration;
FIG. 8 is a right side view of the bicycle light of FIG. 7; FIG. 9 is a rear view of the bicycle light;
FIG. 10 is a side view of a bicycle having a bicycle light according to the invention attached to its seat post;
FIG. 11 is a top view of the bicycle of Figure 10;
FIG. 12 is a top view of the LED and sensor housing unit of the bicycle light; FIG. 13 is a front view of the housing unit of FIG. 12; FIG. 14 is right side view of the light-sensor unit; FIG. 15 is a rear view of the light-sensor unit;
FIG. 16 is a sectional view of the light-sensor unit taken along plane A-A of FIG. 12;
FIG. 17 is a top view of the lid covering the battery cavity in the body of the bicycle light;
FIG. 18 is a right side view of the lid of FIG. 17; FIG. 19 is a top view of the mounting unit of the bicycle light; FIG. 20 is a front view of the mounting unit of FIG. 19; FIG. 21 is a right side view of the mounting unit;
FIG. 22 is a top view of the detaching mechanism for detaching the mounting unit from the body; FIG. 23 is a front view of the body when the mounting unit is detached showing the aperture for receiving the protruding portion of the detaching mechanism;
FIG. 24 is a sectional side view of the detaching mechanism;
FIG. 25 is a front view of the detaching mechanism;
FIG. 26 is a bottom view of the printed circuit board (PCB) showing the primary LED array;
FIG. 27 is a side view of the PCB of FIG. 26 showing the positioning of the LED arrays and the sensor;
FIG. 28 is a front view the PCB;
FIG. 29 is top view of the PCB;
FIG. 30 is a schematic diagram showing the interconnection of the main electronics of the bicycle light;
FIG. 31 is flow chart outlining the operation of the bicycle light; and
FIG. 32 is a diagram showing the bicycle light in operation illuminating a cyclist's back.
PREFERRED EMBODIMENTS OF THE INVENTION
4] Referring initially to Figures 1 to 12, there is provided an illumination device in the form of a portable bicycle light 100. The bicycle light is adapted for illuminating a target object in the form of a cyclist 101 who, in use, rides a bicycle 103. Light 100 includes a rigid elongate plastic body 105. A mount, in the form of a mounting unit 107, maintains the body between the cyclist and a predetermined detection zone 109. As best shown in Figures 13 to 17, light 100 includes a sensor, in the form of an ultrasonic sensor 111, for providing a signal in response to the detection of a foreign object, in the form of a vehicle (not shown), within zone 109. Further, light 100 includes a light source, in the form of an array of LEDs 113, that is indirectly mounted to body 105 and which is responsive to the signal for selectively directing light toward at least a portion of cyclist 101 that faces the vehicle.  Body 105 extends between a first end 115 and a second end 117. End 115 is releasably engagable with unit 107 by a detaching mechanism 119 and spring-loaded detaching switch 121, both of which will be described in more detail below. In an alternative embodiment, body 105 and unit 107 are integral with each other.
 Sensor 111 and LEDs 113 are contained within a common plastics housing 123 which is mounted by a friction hinge 125 between two transversely spaced apart coextensive and opposed arms 127 that extend longitudinally from end 117 of body 105. Hinge 125 allows for constrained rotation of housing 123 about an axis 129 relative to body 105.
 As mentioned above, body 105 is elongate and formed of plastic. In other embodiments, the body is formed of other materials such as steel, aluminium, rubber or an alloy. In further embodiments use is made of deformable materials such as medium density foams or softer plastics, but with reinforcing elements or struts to provide the desired structural integrity. These later embodiments are typically configured to deform, preferably resiliently, in the event of inadvertent contact with other objects, such as when dropped or during an accident involving the rider.
 Body 105 is unitary and ends 115 and 117 are longitudinally spaced apart by about 345 mm. This length provides for portability and allows light 100 to be carried in a backpack or the like when not in use. In alternative embodiments, ends 115 and 117 are longitudinally spaced apart by a distance in the range 200 mm to 500 mm. Body 105 is about 50 mm in transverse width at its widest point. However, in alternative embodiments the transverse width of body 105 is in the range 25 mm to 75 mm. In alternative embodiments, body 105 is adjustable in length, providing capability to select, within a predefined range, the distance that LEDs 113 extend from cyclist 101. For example, in some embodiments, body 105 includes a telescopic member for selectively telescopically extending light 100 into an operative configuration and retracting light 100 into a retracted configuration for storage or the like. This adjustability is advantageous in that a single common form is able to be used to efficiently illuminate cyclists of different size and body shape. It also has the advantage of allowing the cyclist with considerable options for placement on the bike to best affect the illumination.  Referring now to Figures 5 and 6, body 105 defines an internal storage cavity 131 for containing primarily a battery 133. This battery provides power to sensor 111 and LEDs 113 via a two-pin electrical connector 135 and intermediate electrical wiring 137. As shown in Figures 18 and 19, body 105 includes a semi- detachable protective lid 139 for extending across cavity 131 and for allowing selective manual access to battery 133. Lid 139 is formed of a flexible polymer and is snap sealingly engagable with body 105. Alternatively, lid 139 is formed of rubber or other materials, or a combination of these. Mounting pins 141 are integrally connected to body 105 and ensure lid 139 is not fully detached from body 105 when out of snap sealing engagement. In alternative embodiments, lid 139 is fully detachable from body 105, or all components are encased within the unit without user access via a lid.
 When lid 139 is engaged with body 105, cavity 131 provides a substantially waterproof and shockproof housing for battery 133. In other embodiments additional components are also contained within cavity 131. For example, in one embodiment a control switch is contained within the cavity for allowing the user to select one or a plurality of modes for light 100 and/or to adjust the size and extent of the zone 109. In further embodiments, other electronic components are contained within cavity 131.
 Light 100 is activated by manually progressing a two position single throw single pole power switch 143 to an ON position. As shown in Figures 1, 7 and 18, switch 143 is located adjacent cavity 131 and is covered by lid 139 when engaged with body 105 to protect switch 143 from exposure to water and other elements. Switch 143 is actuatable by depressing a portion of lid 139 immediately adjacent the switch, the latter being marked by a standard IEC 5009 power indicium 145. In alternative embodiments, switch 143 is located at other positions on light 100.
 Body 105 also includes an external electrical port 147 for allowing external access to the terminals (not shown) of battery 133. In this embodiment, port 147 also allows external electrical access to the control circuitry in light 100, as is described in more detail below. Port 147 is also adapted for connecting with external accessories that are responsive to the control circuitry within light 100 to provide cyclist 101 with feedback about the condition, status or performance of light 100. This functionality will also be described below in more detail.  Battery 133 is a rechargeable 1.05 Amp/hour DC lithium-ion battery, which provides power for about 10 hours of runtime to a load of about 210 milli-Amps at 12 Volts. In alternative embodiments other types of batteries are used to power light 100. In a particular alternative embodiment, light 100 is powered in part by battery 133 and in part by the dynamic motion of the bicycle's wheels through the implementation of an electric dynamo mounted to one wheel and which is in electrical connection with light 100. In other alternative embodiments, battery 133 is located separate to body 101.
 Referring now to Figures 19 to 21, mounting unit 107 extends longitudinally between a first end 149 and a second end 151. At end 149, unit 107 includes a clamping head 153 and a pair of opposing clamping arms 155 and 157 that extend longitudinally from head 153 for clamping around a structural member, such as a seat post 159 of bicycle 103. Arm 155 is integrally formed with and fixed with respect to head 153, while arm 157 is rotatable with respect to head 153 about a hinge pin 161. Unit 107 includes a generally circular receiving aperture 163 that is collectively defined by head 153 and arms 155 and 157. Aperture 163 is intermediate ends 149 and 151 and is adapted to receive and hold seat post 159 thereby mounting light 100 to bicycle 103.
 Aperture 163 is substantially ringed by a resiliently deformable collar 165 formed of a compressible thermoplastic rubber for enhancing the abutting frictional engagement with post 159. Collar 165 absorbs movement of unit 107 relative to post 159 and reduces the damage to the seat post and mounting unit due to friction. When clamped against post 159, arms 155 and 157 are locked together by a locking screw 167.
 Referring to Figures 22 to 25, unit 107 is, at end 151, pivotably engagable with a detaching mechanism 119 for detaching unit 107 from body 105. Mechanism 119 is rotatable with respect to body 105 about an axis 168 centred on a hex bolt 169. Mechanism 119 includes a protruding structural formation 170 which is snap-lockingly engagable with a complementary locking aperture 171 in end 115 of body 105. Formation 170 is releasable from aperture 171 by depressing a spring-loaded detachment switch 121. That is, switch 121 provides a quick-release function for easy removal of body 105 from bicycle 103 without requiring the detachment of unit 107 from post 159.
 As mechanism 119 is hinged to body 105 it is possible to rotate body 105 with respect to unit 107 to vary the angle of incline of light 100 relative to bicycle 103. In an alternative embodiment a friction hinge is used to allow rotation of unit 107 with respect to body 105. In a further alternative embodiment, a pivot joint is implemented to allow relative rotation of mechanism 119 with respect to body 105 in both the horizontal and the vertical dimensions. For example, in some embodiments, a pivot ball and corresponding socket is implemented. Such pivotable rotation is advantageous in providing more flexibility in the placement of light on the back of cyclist 101. For example, if a cyclist is cycling on the left hand side of a road, body 105 of light 100 can be pivoted horizontally with respect to mechanism 119 to preferably illuminate the cyclist's rear right hand side. This can better define the profile of the cyclist's most vulnerable side. In further alternative embodiments, other hinge, pivot joints or other mechanical linkages are used.
 In alternative embodiments, it will be appreciated that mounting unit 107 takes other forms, including one or more Velcro straps, magnetic connectors or resilient attachment mechanisms.
 Unit 107 is formed of plastic and is about 105 mm in longitudinal length and about 38 mm in transverse width. In alternative embodiments the longitudinal length of unit 107 is in the range of about 75 mm to 150 mm and the transverse width of unit 107 is in the range about 25 mm to 50 mm. Further, in alternative embodiments unit 107 is made of aluminium, an alloy or deformable materials such as medium density foams or softer plastics, but with reinforcing elements or struts to provide the desired structural integrity. These later embodiments are typically configured to deform, preferably resiliently, in the event of inadvertent contact such as when dropped or during an accident involving the rider.
 Referring again to Figures 13 to 17, housing 123 is an elongate assembly extending longitudinally between a first end 173 and a second end 175. Housing 123 is defined by a pair of at least partially transparent lenses 177 and 179 formed of a rigid plastics material and releasably sealed together by a waterproof gasket 181. In other embodiments, lenses 177 and 179 are formed of a deformable material such as medium density foams or softer plastics, but with reinforcing elements or struts to provide the desired structural integrity. Lenses 177 and 179 act as both a protective casing for LEDs 113 and sensor 111, and as optical elements for directing the light emitted from the LEDs 113. As shown in Figure 12, lenses 177 and 179 have predefined patterns 183 engraved in one or more of their respective surfaces for guiding and diffracting emitted light in the desired direction.
 Housing 123 is about 90 mm in longitudinal length and about 30 mm in transverse width. However, in alternative embodiments, the longitudinal length of unit 107 is in the range of about 50 mm to 150 mm and the transverse width of unit 107 is in the range of about 10 mm to 50 mm.
 Referring to Figures 27 to 30, a two-sided printed circuit board (PCB) 185 is located within housing 123 and extends between a first end 173 and a second end 175. Mounted on PCB 185 are various electronic components which will be described below. PCB 185 is electrically connected to battery 133 by electrical wiring 137 for supplying power to the electronic components.
 Referring now to Figures 17 and 28, sensor 111 is located on a first face 187 of PCB 185 intermediate ends 173 and 175 of housing 123. The LED array includes a plurality of sub-arrays. A primary LED sub-array 113a is located at end 175 of a second face 189 of PCB 185. Mounted at end 173 of face 187 is a rear facing LED sub-array 113b for directing light rearward of bicycle 103. A ground illumination LED sub-array 113c is located at end 175 of face 187 of PCB 185 for illuminating the ground beneath bicycle 103. In alternative embodiments other light sources such as halogen lamps, lasers and high intensity discharge lamps are included instead of or in addition to the LED sub-arrays mentioned above. Further, in other embodiments, the electronic components are positioned in different arrangements on PCB 185 and at different locations within light 100.
 LED sub-arrays 113a, 113b and 113c include respective high powered LEDs for efficiently illuminating cyclist 101 and the ground beneath bicycle 103. Referring to Figure 27, sub-array 113a includes four 5 mm white LEDs having a wide beam width of about 80° and being arranged in a diamond pattern. Referring to Figure 30, sub-array 113c includes four 5 mm white LEDs having a wide beam width of about 80° and being arranged in a square pattern.
 Sub-array 113b includes three red SMD (surface mounted diode) type LEDs having a beam width of 120°. One of the red LEDs in sub-array 113b is operatively disposed within a curved reflector unit 191 as shown in Figures 28 to 30. Unit 191 confines and directs light emitted from LED 113b in a specified direction defined by the cone angle of the reflector unit. In alternative embodiments, different numbers and spatial arrangements of LED sub-arrays 113a, 113b and 113c are used. Further, in alternative embodiments LEDs having different beam widths and output light colours are implemented.
 Housing 123 is selectively rotatable between a storage configuration, as shown in Figures 1 to 6, and an operative configuration, as shown in Figure 7 to 9. As mentioned above, rotation occurs about axis 129 by way of friction hinge 125 located between arms 127. Hinge 125 extends through housing 123 adjacent to end 175. In alternative embodiments, hinge 125 extends through housing 123 at other locations. In further alternative embodiments, housing 123 is fixedly mounted to body 105.
 In the storage configuration of Figures 1 to 6, housing 123 is retracted and stored between arms 127 such that housing 123 extends coaxially with body 105. In the operative configuration of Figures 7 to 9, housing 123 extends upward and outward beyond arms 127, as best shown in Figure 8. Referring to Figures 10 and 11, in the operative configuration, sensor 111 is directed rearward of bicycle 103 defining detection zone 109 to detect the presence of vehicles approaching the bicycle from the rear. The spatial characteristics of the detection zone are specified by the particular sensor used.
 Referring specifically to Figure 10, primary LED array 113a, directs a light beam 193 upwardly towards the back of cyclist 101. Also in the operative configuration, rear facing LED array 113b is directed rearward of bicycle 103 thereby transmitting a light beam 195 towards approaching vehicles in the manner of conventional bicycle lights. In the operative configuration, ground illumination LED array 113c directs a light beam 197 downward to illuminate a region of the ground beneath and behind bicycle 103.  Sensor 111 is an ultrasonic sensor that detects vehicles at a distance of up to 200 metres. However, in other embodiments, sensors such as passive infrared sensors and radar/microwave or sonar sensors are used. In one alternative embodiment, a camera is used to capture video of a region behind bicycle 103 and onboard image recognition software is used to process the video and identify nearby vehicles.
 Referring to Figure 30, PCB 185 also includes control logic in the form of an integrated circuit 199 (not shown on PCB) for controlling light 100. Circuit 199 includes a processor 201 for executing instructions and a database 203 for storing and retrieving data such as lookup table information. Sensor 111 sends detection signals to processor 201, which retrieves information from database 203 to selectively transmit illumination signals to one or more of sub-arrays 113a, 113b and 113c. Information is transmitted to various accessories through port 147. Battery 133 provides electrical power to all of the electronics of light 100.
 Circuit 199, processor 201 and database 203 are hereinafter collectively referred to as a control unit 205. As previously mentioned, circuit 199 is located on PCB 185 inside housing 123. However, in alternative embodiments circuit 199 is located elsewhere within light 100, such as in or adjacent cavity 131.
 Referring again to Figures 10 and 11, light 100 further includes feedback means, in the form of an LCD (liquid crystal display) unit 207, which is responsive to the detection signal to communicate to cyclist 101 the presence and proximity of a detected vehicle. Unit 207 is electrically coupled to a processor for controlling functions of light 100. In alternative embodiments, feedback is provided to cyclist 113 by other means such as a flashing LED. In some embodiments, an LED or LCD displayis provided and configured to flash with an intensity and/or frequency that is dependent upon the proximity of the approaching vehicle. Further, in other embodiments, simply the presence of a detected nearby vehicle, and not proximity information, is communicated to cyclist 101. LCD 207 is mounted on the handlebars 209 of bicycle 103, and is in electrical communication with battery 133 and circuit 199 through port 147. In alternative embodiments, unit 207 is mounted elsewhere on bicycle 103 or to cyclist 101. In alternative embodiments, light 100 further includes speaker output for providing audio feedback to cyclist 101 when a nearby vehicle is detected. In further alternative embodiments, speaker output is provided through unit 207.
 It will be appreciated that another aspect of the invention relates to interfacing light 100 with an on-board computer of bicycle 103. In one embodiment, light 100 is configured to interface directly with that system through electrical port 147 on body 105. In some embodiments, installable software is able to update the on-board computer system to efficiently receive and display information from light 100. Electrical port 147 is also capable of communicating information to cyclist 101 regarding the performance of light 100 and for also sending control instructions to light 100 through control circuitry on PCB 185. For example, in one embodiment, battery life of battery 133 is displayed to cyclist 101 through unit 207. Cyclist 101 also has the option, by appropriate operation of the on-board computer system, to reduce the intensity of LEDs 113 to preserve battery life or increase the intensity, say if the cyclist is in conditions of particularly bad visibility. Other control options include changing the intermittent flashing frequency or colour of the light transmitted from LEDs 113.
 To mount light 100 to post 159, arm 157 is first rotated so that it is disengaged from arm 155. This allows post 159 to be easily passed between open arms 155 and 157 and received in aperture 163. Arm 157 is then rotated back toward arm 155 and locked with respect to arm 155 by screw 167. With light 100 mounted to bicycle 103, end 117 of body 105 extends substantially rearward of the bicycle's forward direction such that sub-array 113a directs light beam 193 onto the back of cyclist 101.
 The operation of the bicycle light will now be described with reference to the flowchart of Figure 31. With light 100 mounted to bicycle 103, the light is activated by progressing power switch 143 to the ON position. At step 300 sensor 111 scans for vehicles present in detection zone 109. At step 302 sensor 111 detects a vehicle within the detection zone and subsequently, at step 304, sends a detection signal to unit 205. This signal includes data indicative of the distance of the vehicle from sensor 111. Based on the detection signal information, at step 306, unit 205 extracts instructions from a data look up table stored in database 203 and, at step 308, sends an illumination signal to sub-array 113a. At step 310, this illumination signal selectively actuates sub- array 113a to illuminate cyclist 101. Sub-arrays 113b and 113c provide constant illumination. However, in alternative embodiments, sub-arrays 113b and 113c are also selectively actuated based on the detection of a vehicle.
 Referring to Figure 32, in the operative configuration beam 193 is directed upward towards cyclist 101 to thereby illuminate at least a portion of the cyclist's back. More particularly, beam 193 is directed such that it is diffusely reflected off the back of cyclist 101 in a range of angles. As the cyclist's back is facing generally rearward, a significant percentage of beam 193 is reflected in the direction of the nearby vehicle. This reveals the cyclist to the driver of the vehicle. In alternative embodiments the light is directed to other portions of bicycle 103 or cyclist 101.
 The information extracted from a lookup table in database 203 includes frequency and brightness information for sub-array 113a. As the proximity of the vehicle becomes closer, the frequency and brightness of sub-array 113a increases, thereby making the presence of cyclist 101 more apparent to the driver of the vehicle.
 An example lookup table is set out below.
 In an alternative embodiment, one or more of LED sub-arrays 113a, 113b and 113c are adapted to change the colour of beam 193 in response to the proximity of an approaching vehicle.
 In a further alternative embodiment, light 100 includes additional LED arrays which selectively direct beam 193 or additional beams onto cyclist 101 or bicycle 103 from one or more sides. These additional LED arrays are actuated in response to the position of a vehicle being detected within detection zone 109. In this way, when a vehicle is detected as approaching bicycle 103 from the rear on the right, cyclist 101 is selectively illuminated both on the rear and right sides. Similarly, when a vehicle is detected as approaching bicycle 103 from the rear on the left, cyclist 101 is selectively illuminated both on the rear and left sides.
 Light 100 is adapted to provide further electronics functionality including battery life and charge information, and GPS connectivity. In alternative embodiments, light 100 is capable of communicating with external devices via Bluetooth™ for transferring data.
 In an alternative embodiment, light 100 is adapted to project a predefined image on the back of cyclist 101. This is achieved by passing the emitted light through a predefined mask to produce a predetermined image. This presents an opportunity for businesses to advertise using light 100.
 While the invention is intended for use with a bicycle, it will be appreciated that light 100 can also be applied to other vehicles and in other situations. For example, in one alternative embodiment, light 100 is used to selectively illuminate a broken down vehicle or vehicle parked on a roadside to reveal a portion of the vehicle to passing cars. In this embodiment, light 100 is situated on or adjacent the broken down vehicle with sensor 111 directed towards oncoming traffic. LEDs 113 are directed towards one or more faces of the broken down vehicle such that, when another vehicle enters detection zone 109 LEDs 113 illuminate the one or more faces of the broken down vehicle. This increases the likelihood of the driver of the oncoming vehicle becoming aware of the broken down vehicle and thereby providing more time to take evasive action to avoid a collision.
 It will be appreciated that, in other embodiments, body 105 is shaped differently to facilitate mounting directly on the road adjacent to the broken down vehicle, or on the broken down vehicle itself. Alternatively, light 100 is able to be provided with a separate and releasably engageable stand for allowing placement of light 100 at a desired location.
 In another alternative embodiment, light 100 is adapted to be releasably or fixedly mounted to a motorcycle (not shown). In this embodiment, light 100 operates in a similar manner to that disclosed in relation to a bicycle to selectively illuminate the motorcyclist and optionally other areas on or around the motorcycle. In one alternative embodiment, light 100 is integrated into the tail-light cluster of the motorcycle and wired into the motorcycle's existing power supply. In a further alternative embodiment, light 100 is adapted to actuate in conjunction with the motorcycle's hazard light system. As a motorcycle is a more substantive object than a bicycle, it offers a wider variety of mounting points. Moreover, as use is made of an existing power supply, the battery in light 100 is able to be eliminated. In one embodiment, light 100 is adapted to selectively illuminate one or more sides of the motorcycle in response to the detection of a vehicle in a direction from the motorcycle. In this way, the motorcycle is selectively made more visible to those vehicles that are approaching the motorcycle, for example, from adjacent lanes, to increase the chances of the driver of the relevant vehicles being made aware of the presence of the motorcycle.
 In another alternative embodiment, light 100 is adapted to be releasably mounted to the hull of a boat. In this embodiment sensor 111 detects nearby watercraft and, in response, selectively illuminates one or more passengers in the boat and/or a portion of the boat itself.
 In a further alternative embodiment, light 100 is adapted to be releasably mounted to an ultra light aircraft. In this embodiment light 100 is mounted to the tail of the ultra light and the sensor detects the presence of nearby aircraft. In response, one or more portions of the ultra light aircraft are selectively illuminated thereby revealing the ultra light to the nearby aircraft.
 In another embodiment, light 100 is adapted to be releasably mounted to an advertising billboard placed near a road or footpath/sidewalk. In this embodiment, sensor 111 is directed to detect vehicles or people approaching the billboard and selectively illuminate the billboard upon detection. In this manner, the lighting of an advertising billboard is left switched off until detection is made of a nearby vehicle or person who is within a zone that is determined as suitable for viewing the billboard.
 It will be appreciated that the described bicycle light 100 is able to operate independently or in conjunction with other bicycle lights. For example, a bicycle is able to be equipped with both conventional bicycle lights and the above described bicycle light.  It will be appreciated that the above-disclosed bicycle light 100 detects vehicles in the proximity of cyclist 101 riding bicycle 103 and, in response, selectively illuminates the cyclist's back to make nearby vehicles more aware of the cyclist. When compared to the prior art, this provides at least the following advantages:
> ■ The cyclist's back provides a large solid object for better reflecting light towards nearby vehicles. · As the cyclist's back is predominantly directed rearward toward approaching vehicles, a large portion of the light directed at the cyclist's back will be reflected towards an approaching vehicle and detected by the driver of that vehicle. Being the target of the light, the cyclist's back displays human characteristics to the driver of a nearby vehicle. In contrast, typical bicycle lights represent a disembodied light source that can easily be dismissed or mistaken for other light sources not deemed to be of immediate concern. For example, a motorist may mistake a bicycle having a typical light as a background street or house light. A driver is more likely to notice and subsequently avoid a human target than an inanimate object such as a bicycle frame or point light source.
 Ground illumination sub-array 113c illuminates the ground beneath bicycle 103. This further helps motorists identify the target as a person riding a bicycle rather than a generic light source. This further helps motorists perceive the depth of the bicycle as a target, allowing them to gain a better feel for the proximity and speed of the bicycle.
 In many accidents involving cyclists and motor vehicles, the cyclist is struck from the side by the vehicle. This problem is not overcome by typical bicycle lights, which generally only include forward and rear facing lamps. In contrast, bicycle light 100 of the present invention illuminates the cyclist's back which reflects light at a range of angles both behind and beside cyclist 101. Further, ground illumination sub- array 113c also scatters light over a range of angles, thereby illuminating bicycle 103 and cyclist 101 from the sides. In this way, motorists driving behind and beside the bicycle are more cognisant of the bicycle's presence, position and speed.  An advantage of implementing an ultrasonic sensor is that specific programming ensures only vehicles approaching a cyclist are detected. Similarly, use of a passive infrared sensor in light 100 ensures that only objects emitting infrared radiation or heat will be detected by sensor 111. In either case, , sensor 111 will easily detect approaching vehicles, which have motion and which radiate heat, but will not detect sign posts or other passing objects that are generally not a danger to cyclist 101.
 Due to the nature of light 100, the need for additional safety vests and apparel, which are considered unfashionable by some, is made redundant. Therefore, the amount of additional equipment and apparel required by cyclist 101 is reduced.
 The size and releasable nature of light 100 makes it portable. In this way cyclist 101 can quickly and easily detach light 100 from bicycle 103 and store the light in a backpack when it is not needed.
 Thus, while there has been described what are believed to be the preferred embodiments of the invention, those skilled in the art will recognize that other and further modifications may be made thereto without departing from the spirit of the invention, and it is intended to claim all such changes and modifications as fall within the scope of the invention. For example, any formulas given above are merely representative of procedures that may be used. Functionality may be added or deleted from the drawings and features may be interchanged. Steps may be added or deleted to methods described within the scope of the present invention.
 Unless specifically stated otherwise, as apparent from the following discussions, it is appreciated that throughout the specification discussions utilizing terms such as "processing," "computing," "calculating," "determining", analysing" or the like, refer to the action and/or processes of a computer or computing system, or similar electronic computing device, that manipulate and/or transform data represented as physical, such as electronic, quantities into other data similarly represented as physical quantities.
 In a similar manner, the term "processor" may refer to any device or portion of a device that processes electronic data, e.g., from registers and/or memory to transform that electronic data into other electronic data that, e.g., may be stored in registers and/or memory. A "computer" or a "computing machine" or a "computing platform" may include one or more processors.
 It should be appreciated that in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of this invention.
 Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.
 In the description provided herein, numerous specific details are set forth.
However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.