This invention relates generally to an anti-theft device for a bicycle and, more particularly, to a removable bicycle accessory comprising and/or incorporating an anti-theft device.

Anti-theft devices for vehicles such as bicycles are known. One such device comprises a housing containing the electronic elements of an alarm, some means for clamping, or otherwise removably attaching, the device to a bicycle, and means for selectively arming and disarming the device. For example, UK Patent No. GB 1409923 describes such a device, in which a sound transducer, oscillator, pendulum switch and battery are arranged within a housing, and the housing can be clamped to a bicycle. A wing nut secures the clamp, and a padlock shackle is passed through an aperture adjacent the nut to prevent it from being loosened. The padlock serves two purposes, namely to prevent unauthorised removal of the device from the bicycle and also to prevent unauthorised arming and disarming of the device, since this can only be achieved when the padlock has been removed from the above-mentioned aperture.

However, such devices must be armed and disarmed by some form of mechanical key pad, FOB or mobile app. Furthermore, an alarm device of this type is required to be removed from the bicycle in order for the battery to be recharged. Still further, such devices cannot assist in preventing the theft of removable bicycle accessories, such as a bicycle light, and bicycle light theft is a growing problem which is not addressed by conventional anti-theft devices for bicycles. Furthermore, the use of a mechanical anti- tamper means, namely the above-mentioned padlock, provides limited security as it can be relatively easily forcibly removed, using bolt cutters or similar cutting implements. Whilst the alarm may, if armed, sound initially when the padlock is being removed, it can subsequently be quickly disarmed and thus silenced. Still further, there is an ongoing desire to minimise the weight of, and/or carried by, a bicycle frame. In respect of the above- described types of anti-theft device, the user must either remove the anti-theft device entirely from the bicycle frame when not required for use, and carry it separately, which is clearly inconvenient, or they may leave the anti-theft device clamped to the bicycle frame when it is not required for use (i.e. during normal use of the bicycle) and accept the resultant undesirable additional weight carried on the bicycle frame.

Aspects of the present invention seek to address at least some of these issues and, in accordance with a first aspect of the present invention, there is provided a portable accessory device for a vehicle, the device comprising a first unit comprising a module configured to be removably mounted in or on said vehicle, wherein a vehicle accessory unit and an audible sounder unit are provided at an outer surface of said module, the device further comprising one or more electronics modules within said module and communicably coupled to said sounder unit for selective operation thereof, wherein said one or more electronics modules include(s):

- an alarm circuit configured to be selectively armed or disarmed and which, when armed, causes said sounder unit to be operated in response to unauthorized movement of said vehicle; and

- a vehicle accessory operation circuit, configured to enable a user to selectively operate said vehicle accessory.

According to an exemplary embodiment of the present invention, the module may comprise an alarm unit and the vehicle accessory unit may be removably physically and communicably coupled to the alarm unit. The alarm circuit may optionally be provided in the alarm unit and configured to be selectively armed or disarmed, and an alarm arming/disarming circuit may be provided in the vehicle accessory unit and configured for communication with the alarm circuit when the vehicle accessory unit is physically coupled to the alarm unit.

In one exemplary embodiment of the present invention, the alarm circuit and arming/ disarming circuits may be configured such that physically coupling the vehicle accessory unit to said alarm unit may cause the alarm circuit to be disarmed, and removing the vehicle accessory unit may cause said alarm circuit to be armed.

According to a second aspect of the present invention there is provided, a portable accessory device comprising a first unit comprising a module configured to be removably mounted in or on said vehicle, said module comprising an alarm unit, wherein a vehicle accessory unit and an audible sounder unit are provided at an outer surface of said module, the vehicle accessory unit being removably physically and communicably coupled to said alarm unit, the device further comprising one or more electronics modules within said module and communicably coupled to said sounder unit for selective operation thereof, wherein said one or more electronics modules include(s):

- an alarm circuit provided in said alarm unit and configured to be selectively armed or disarmed and which, when armed, causes said sounder unit to be operated in response to unauthorized movement of said vehicle;

- an arming/disarming circuit provided in said vehicle accessory unit configured for communications with said alarm circuit when said vehicle accessory unit is physically coupled to said alarm unit; and - a vehicle accessory operation circuit, configured to enable a user to selectively operate said vehicle accessory; wherein said alarm circuit and arming/disarming circuits are configured such that physically coupling said vehicle accessory unit to said alarm unit causes said alarm circuit to be disarmed, and removing said vehicle accessory unit causes said alarm circuit to be armed. Optionally the vehicle accessory unit may be a lamp unit.

In one exemplary embodiment the vehicle accessory unit may comprise a first rechargeable power source. A charging port may optionally be provided in the vehicle accessory unit for recharging the first rechargeable power source. In an exemplary embodiment, the alarm unit may comprise a second rechargeable power source, and the device may be configured such that the second rechargeable power source may be recharged by the first rechargeable power source when the vehicle accessory unit is physically and communicable coupled to the alarm unit.

According to an exemplary embodiment of the present invention, the device may further comprise a light operation circuit, which may be configured to enable a user to selectively switch the light unit on when required to illuminate the route of the vehicle, in use.

Optionally, the alarm unit and the vehicle accessory unit may be configured to be slidably engagable to enable them to be removably physically coupled together. One of the alarm unit and the vehicle accessory unit may optionally include a pair of rails and the other of the alarm unit and the vehicle accessory unit may optionally comprise a pair of grooves, the rails and grooves may be slidably interengagable to enable the alarm unit and vehicle accessory unit to be removably physically coupled together.

In an exemplary embodiment of the present invention the alarm unit and the vehicle accessory unit may comprise a unique electronic identifier, and the alarm unit may optionally be configured to communicate only with the vehicle accessory unit carrying the unique electronic identifier.

Optionally, the sounder unit may be provided externally of a first side of the alarm unit and the lamp unit may be provided externally on an opposing side of the vehicle accessory unit, wherein, in use, when the device may optionally be mounted in or on the vehicle and the vehicle accessory unit may be mounted in or on of the alarm unit, the lamp unit may face a direction of forward travel of the vehicle, and the sounder unit may face an opposite direction.

The electronics module may optionally further include a motion sensor for detecting movement of the vehicle. The alarm circuit may be selectively actuated when the movement detected by the motion sensor exceeds a predetermined dynamic threshold.

In an exemplary embodiment of the present invention, the housing may comprise at least two housing parts that may be selectively moveable relative to each other between an open configuration in which said device may be applied to or removed from the vehicle, and a closed configuration in which the device may be fixed in or on the vehicle.

According to one exemplary embodiment of the invention, the device may comprise an attachment mechanism arranged and configured to enable a user to optionally manually fix the housing parts together in a closed configuration, or optionally manually release the housing parts to enable them to be moved to the open configuration.

The device may optionally comprise a preventative device for preventing unauthorized manual release of the attachment mechanism.

In an exemplary embodiment the device may comprise a wireless communications module. According to one exemplary embodiment of the invention, the attachment mechanism comprises an electronic latching mechanism. The electronic latching mechanism may optionally be a solenoid latching mechanism. The electronic latching mechanism may comprise a motor and gear system. In an exemplary embodiment, the electronic latching mechanism may optionally be configured to be moved from an unlocked configuration to a locked configuration when the alarm circuit is armed.

These and other aspects of the present invention will be apparent from the following specific description, in which embodiments of the present invention are described, by way of examples only, and with reference to the accompanying drawings, in which:

Figures 1A and IB are schematic front and rear perspective illustrations respectively of a device according to a third exemplary embodiment of the present invention;

Figure 2A and 2B are schematic perspective illustrations of the alarm unit of the device of Figures 1A and IB;

Figure 3 is schematic bottom perspective view of the lamp unit of the device of Figures 1A and IB;

Figure 4 is a schematic perspective view of the device of Figures 1A and IB with the housing removed;

Figure 5 is a schematic diagram of a device according to an exemplary embodiment of the present invention, when in a closed configuration;

Figure 6 is a schematic illustration of the device of Figure 5 in an open configuration;

Figure 7 is a schematic cross-sectional side illustration of a device according to another exemplary embodiment of the invention, when in a closed configuration;

Figure 8 is a schematic illustration of the device of Figure 7, as seen from the back, with the lower portion of the device shown in cross-section; and

Figure 9 is a schematic illustration of a close up of the clip of the device of Figure 7.

Referring to Figures 1A and IB of the drawings, an exemplary embodiment of the invention comprises an alarm unit 40, configured to be mounted to a portion of a bicycle (e.g. the handlebar or stem) and a removable lamp unit 42.

Referring additionally to Figure 2A and 2B, the alarm unit 40 comprises a housing of generally rectangular cross-section and an attachment device 46 connected to a surface of the first unit 40, defining the bottom of the device when it is oriented for use. In practice, the device may be utilised in any orientation, however for optimal performance, the device is preferably oriented with the attachment device directed downwardly toward the ground. In the following description, directional indicators ("upwardly", "forward", "backward", etc.) describe the device when in the preferred orientation.

The attachment device 46 comprises a hose clamp, having a strip of flexible strong material (usually galvanized steel) curved into a circular band with equally spaced 'notches' or protuberances along its length. A worm drive 47 is fixed at a point around the circular band, and fused or otherwise fixedly attached to one end of the strip. The 'teeth' of the worm drive 47 engage with the notches or protuberances on the surface of the strip and, as the worm drive 47 is rotated, moves the strip in one direction or the other, depending on the rotational direction, thereby increasing or decreasing the diameter of the circular band to enable it to be respectively loosened or tightened around a bar or other part of a bicycle. Such hose clamps are known in the art and the invention is not necessarily intended to be limited in this regard, in that the suitable mechanical attachment devices are envisaged. Typically, such worm drives 47 have a screw-type head and are operable using a screwdriver or Allen key. They are generally known to be very secure. In the present embodiment the worm drive is housed within the body of the alarm unit 40 and accessible only through a closable opening 48. The closable opening 48 has a cover 50 which is removably fitted over the opening in order to hide or prevent access to the worm drive 47.

For added security, and referring in particular to Figure 2B of the drawings, a custom screw head 52 may be fitted over the screw head of the worm drive 47 having a custom shaped recess 54 within it. In use, the custom screw head 52 will be permanently fitted to the screw head of the worm drive 47. The user will be provided with a custom tool which fits in the custom screw head 52. This allows the device to be even more securely fitted to the bicycle, since removal thereof requires a custom tool only held by the user.

The upper surface of the alarm unit has an elongate, generally concave channel 56 running along its length. A generally concave cradle 58 is located generally centrally within the channel 56, the cradle 58 having a pair of elongate, parallel rails 60 which extend upwardly a short distance, not extending higher than the edges of the upper surface of the alarm unit 40. Three apertures 62 extend downwardly through the upper surface of the first unit. These apertures 62 provide connection access to the electronics module located within the first unit 40, as will be described in more detail hereinafter.

Referring now to Figure 3 of the drawings, the lamp unit 42 comprises a generally cylindrical body having a light unit 44 at one end. The unit is illustrated in Figure 3 of the drawings as it would be viewed from underneath. A pair of elongate formations 64 extend from opposing side 'edges' to form respective elongate guide channels that slidably engage, in use with the rails 60 on the alarm unit 40. The lamp unit 42 can therefore be slidably attached to the alarm unit 40 when the device is in a first configuration for use as a bicycle light. Three pins 66 are positioned to correspond with the three apertures 62 on the upper surface of the alarm unit 40. When the device is in the first configuration, pins 66 extend downwardly into the apertures 62 and provide electrical coupling between the alarm unit 40 and the lamp unit 42. The pins 66 are electrically coupled to an electronics module within the lamp unit 42, which includes the light unit 44, and other electrical components described in further detail hereinafter. When the lamp unit 42 is mounted on the alarm unit 40 in a first configuration, the light unit 44 defines the front of the device, thereby making it forward facing in use, to illuminate the direction of travel of the bicycle.

Referring to Figure 4 of the drawings, the electrical modules contained within the alarm and lamp units 40, 42 are illustrated. The attachment device 46 denotes the bottom of the device, whilst the light unit 44 denotes the front, when the device is in a preferred orientation for use. The first electronics module 68 is housed within the alarm unit 40, and a second electronics module 70 is housed within the lamp unit 42. The first electronics module 68 comprises a first PCB 72, a power source 74 and a sounder unit 76. The first PCB 72 comprises a motion sensor and an alarm system. The motion sensor detects movement of the bicycle, and then checks the movement against a dynamic threshold to determine if the movement is "authorized" or "unauthorized". "Authorized" movement may comprise small movements such as the bicycle (to which the device is attached) being accidentally nudged. 'Unauthorized' movement may indicate a theft or attempted tempering with the device. This ensures minimal "false" alarms. The alarm system is configured to emit an alarm when the device detects unauthorized movement with motion sensor, but only if the alarm system is armed. The second electronics module comprises a light unit 44, a power source 80, and a second PCB 82.

When the device is in the first configuration as illustrated in Figures 1A, IB and 4 (i.e. with the lamp unit 42 connected to the alarm unit 40 via the guide channels (on the lamp unit 42) and the rails 60 (on the alarm unit 40)), the alarm unit 40 is disarmed. The electrical coupling between the alarm unit 40 and the lamp unit 42 signals the microprocessor to disarm the alarm. In use, the user may be travelling on the bicycle, then, when they arrive at the destination, they remove the lamp unit 42 from the alarm unit 40, thus, breaking the electrical coupling between the alarm and lamp units 40, 42 and arming the alarm system is armed. Any unauthorized movement which occurs during the time when the alarm system is armed will automatically cause the sounder unit 76 to emit an alarm.

If a user wishes to remove the lamp unit 42 from the alarm unit 40, without arming the alarm system, they can manually disarm the device by pressing the power off button 84 on the side of the lamp unit 42. This must be done whilst the lamp unit 42 is still mounted in the alarm unit 40 in order to signal the microprocessor before the electrical coupling is broken. This advantageously provides the user with more flexibility. The power sources 74, 80, are preferably rechargeable battery cells. Referring back to Figure 3 of the drawings, the power source 80 in the lamp unit 42 can be charged as required, and in a conventional manner, via a USB port 83 on the bottom of the lamp unit 42. When the device is in the first configuration (i.e. the lamp unit 42 is mounted in, and electrically coupled to, the alarm unit 40), power from the lamp unit 42 can charge the power source 74 of the alarm unit 40. In use, the power source 74 of the alarm unit 42 may be capable of retaining sufficient power for up to 10 days or more. Thus, the user only needs to charges the lamp unit 42 to gain functionality of the lamp and alarm units 42, 40, and the longevity of the alarm unit power source is such that the alarm unit 40 will offer the user the protection of the alarm system, even when the lamp unit 42 is not mounted therein, for a considerable period of time. There is no need to remove the alarm unit 40 if the user regularly charges and replaced the lamp unit 42, thus providing a completer (permanent) security solution. This is in contrast to known alarm systems which usually require removal of the battery (or the entire alarm unit) for charging such that there is a period of time when the bicycle is unprotected.

The sounder unit is beneficially directed rearwardly, toward the driver of the bicycle, in order to discourage theft. It is envisaged that the sounder unit 76 may produce a sound level of around 140 dB and it is thought that if such an alarm is sounding directly at a rider, it would discourage a thief from continuing any attempt of theft of the bicycle and will, in any event, alert passers by and draw attention to the theft. The light unit 44, as described above, points in the direction of travel, when mounted for use. The user may selectively activate the light unit 44 by a switch 86 on the upper surface of the second unit 42. The light unit 44 may also be activated when the second unit 42 is not mounted for use as a bicycle light, and therefore may advantageously be used as a hand-held torch. Optionally, the user may mount a power unit (not shown) in place of the lamp unit 42 on the alarm unit 40, when they wish to leave their bicycle for a longer period of time. The power unit would provide power to the alarm unit for up to 6 months, or possibly longer, and would be configured such that it cannot be electrically coupled to the alarm system, and therefore cannot arm or disarm the alarm unit. The alarm unit 42 may optionally include a wireless communications module within it electronics module 68, which communicates wirelessly with other devices, for example a bicycle lock. The present embodiment of the invention provides the user with a simple-to-use security measure which can help prevent theft of the vehicle. The unique combination of features allows the user to quickly and simply arm the device without the need to reaching in a bag and activating a FOB or manually locking and arming a device. The user removes the lamp unit 42 (or other accessory) which they would do so when leaving the bicycle in any case, and so the routine of the user does not need to be changed. This act arms the bicycle, the user only needing to change his routine to not arm the device when removing the lamp unit 42 (or other accessory). This much reduces the chance of the user forgetting to set the alarm, as with the prior art solutions. Referring to Figure 5 of the drawings, there is illustrated a bicycle accessory according to a second exemplary embodiment of the present invention. The accessory comprises a housing 10 formed of two sections 12, 14. The profile of the outer periphery of the housing sections 12, 14 is a matter of design choice. In the illustrated embodiment, for example, the outer profile of the first housing section 12 is generally rectangular, and the outer profile of the second housing section is generally semi-circular. However, the respective profiles of the adjoining walls of the first and second housing sections are substantially identical, each comprising a flat portion extending from each of its outer edges to a generally central semi- circular recess, such that when the adjoining walls are abutted, as shown in Figure 5, the semi-circular recesses, together, form a central hole 16. The first and second housing sections 12, 14 are connected together at one edge by a hinge mechanism 18 such that the two housing sections can be moved relative to each other between a closed configuration as shown in Figure 5 of the drawings, in which they are fully abutted, and an open configuration as shown in Figure 6 of the drawings, in which the above-mentioned adjoining walls are separated, the hole 16 is open and the only connection between the housing sections is at the hinge mechanism 18. In the open configuration, the device can be mounted onto a tubular part of the bicycle frame, for example, the handlebar, head tube or stem. The tubular part of the bicycle frame is captured within the semi-circular recesses of the adjoining walls of the first and second housing sections 12, 14 and the housing sections 12, 14 can then be brought together into the closed configuration (Figure 5), such that the tubular bicycle frame part is encapsulated within the central hole 16.

Referring to Figures 7 to 9 of the drawings, in the exemplary embodiment illustrated, a mechanical mechanism, characterised by a lever 20, may be provided for manually latching the two housing sections 12, 14 in the closed configuration and selectively releasing them to allow the device to be moved into the open configuration. The mechanical mechanism comprises a lever 20, and a clip 36. The resiliency flexible clip 36 comprises two toothed prongs 36a, 36b, similar to that which may be found on a helmet chin strap fastener, for example. The prongs 36a, 36b extend from the adjoining wall of the second housing section 14. When the device is closed, as shown in Figures 6 and 7, the prongs 36a, 36b extend through a respective corresponding aperture on the adjoining wall of the first housing sectionl 2. Each aperture is shaped such that the respective prong 36a, 36b must be compressed in order for the widest point of its respective tooth to pass through the aperture. Once through, the prongs 36a, 36b can return to their original position and the teeth now hold the first and second housing sections 12, 14 in the closed configuration. Manual application of force to two side buttons 37 compress or 'squeeze' the prongs 36a, 36b so that the teeth may pass back through the aperture, and the device may be opened to the open configuration.

The lever 20 is generally 'L' -shaped and hingedly attached to the second housing section 14. The lever 20 is pivotable from a first closed position as shown in Figure 5 of the drawings, to a second released position as shown in Figure 6 and 7 of the drawings. The lever is communicably coupled to the prongs 36a, 36b. When the device is in the closed configuration and the lever 20 is in the released position, the short arm of the 'L' -shaped lever is pushed upwards on the prongs. The first and second housing portions 12, 14 are not tightly held together and the central hole diameter may be expanded by substantially 2mm, though this expansion may be anything in the range of 0.5mm - 5mm, and the invention is not intended to be limited in this regard. When the device is in a close configuration and the lever 20 is in a closed position, the short arm of the 'L' -shaped lever is pulling on the prongs 36a, 36b. The first and second housing portions 12, 14 are therefore held tightly together. In use, enlarging the diameter of the central hole 16 allows rotation of the device around a tubular part of a bicycle frame, while tightening the central hole 16 allows the device to be fixed in place.

It will be appreciated that manual latching mechanisms are known, and several suitable such mechanisms will be apparent to a person skilled in the art, and the present invention is not necessarily intended to be limited in this regard. For additional security and anti-tamper functionality, it is envisaged that an electronic latching mechanism may also be provided and completely concealed within the housing 10. In the exemplary embodiment illustrated in Figures 5 and 6 of the drawings, such an electronic latching mechanism is exemplified by a latching solenoid 22 mounted within the first housing section 12. Latching solenoids are known in the art and typically comprise a housing 24 within which a solenoid in the form of a coil is arranged at one end and a permanent magnet and stationary pole is mounted at the opposing end. A plunger including an armature 26 is mounted within the coil for longitudinal movement toward or away from the stationary pole, depending on the direction of current passing through the coil field. An extension spring may be provided to bias the plunger/armature away from the pole (i.e. toward the "locking" position). A locking member (not shown) including an aperture or recess for receiving/retaining the armature, when in the locking position, may be mounted in a suitable location relative to the armature 26. In an exemplary embodiment, for example, such a locking member may extend from a location near the outer edge of the second housing section (on the opening side of the device) into a cavity in the immediately opposing part of the first housing section 12, such that its distal end is located adjacent the armature 26 and, when the armature is in the locking position, it is received within an aperture or recess defined in the distal end of the locking member to retain the first and second housing sections in the closed configuration.

In use, and from the above-described locking position, current is caused to flow in a first direction, energising the coil field in the solenoid, which adds to the pull of the permanent magnet. This overcomes the spring bias and causes the plunger/armature to be attracted to the stationary pole within the housing and away from the locking member. Once the armature 26 has moved full travel and is in contact with the pole, it will be retained in this position, without further electrical power input, by the permanent magnet. To release the solenoid from this "unlocked" position, the magnet's attraction is cancelled by sending a current back through the coil field in the opposite direction, and the plunger/armature is moved, as a result, to the locked position by the biasing spring, and will remain there until a current in the above-mentioned first direction is once again passed through the coil field.

In a second exemplary embodiment of the invention, the electronic latching system comprises a motor and gearbox system. A motor concealed within the housing 10 can be manually or wirelessly switched on which pushes the armature 26 in a forward or reverse direction, depending on whether the device is being locked or unlocked, by means of a gear mechanism. In one exemplary embodiment the armature 26 may be located in the second housing section 14. To lock the device, the motor is switched on and the armature 26 is pushed into a corresponding cavity in the first housing section 12. Similarly, to unlock the motor is switched on and the motor rotates the gear in the opposing direction to pull the armature 26 out of the cavity. Alternatively, the armature 26 and cavity may be on the first and second housing sections 12, 14 respectively.

Either of the electronic securing means may also trigger a plate 38 to automatically be inserted between the two prongs 36a, 36b. The plate should be of a thickness such that manual application of force to the buttons 37 cannot compress the prongs 36a, 36b such that the teeth may pass back through the respective aperture. This provides a further security measure such that the device cannot easily be removed.

Referring back to Figures 5 and 6 of the drawings, each of the housing sections 12, 14 defines a separate cavity within which elements of the device are housed. Thus, in this particular exemplary embodiment, the second housing section 14 may house a rechargeable battery unit 28, and the electronics unit 30 for the alarm system, solenoid or motor operation and bicycle light operation may be housed in the first housing section 12. As illustrated, a bicycle light (e.g. LED) 32 is mounted in an opening on one side of the first housing section (hereinafter referred to as the "front" of the device), and an audible alarm unit 34, such as piezo siren or the like, is mounted on the opposing "rear" side of the first housing section 12.

Obviously, the device is configured such that the light 32 faces to the front to illuminate the route along which the bicycle is travelling. The alarm unit 34 is advantageously located toward the rear of the device, i.e. toward the rider. It is envisaged that the alarm unit may produce a sound level of around 140dB and it is thought that if such an alarm is sounding directly at a rider, it would discourage a thief from continuing any attempt of theft of the bicycle.

The electronics module 30 incorporates a motion sensor alarm circuit, including a wireless switch operable by a battery-powered fob or similar device using radio frequency at close range (e.g. <100m) to arm and disarm the alarm function. The fob (not shown), which may be battery powered, may include a panic button as well as an arm and disarm button. Thus, the motion sensor alarm circuitry may include a bypass element and a switch, in this case wireless, which, when closed, triggers the alarm unit 34 to sound, in the manner of a panic alarm. The electronics module 34 further includes the circuitry for operating the bicycle light 32 and may, for example, include a simple on/off switch (wireless or otherwise) to enable the user to selectively switch the light 32 on or off, as required. However, in some exemplary embodiments, the circuit may, alternatively or in addition, incorporate a light sensor configured to sense ambient light and switch the bicycle light 32 on automatically when the ambient light falls below a predetermined level.

The electronics module is provided with electrical power by the battery unit 28, which may be rechargeable via a USB connection or the like. The battery itself may be conventional Lithium ion battery. In use, the user may mount the device 10 onto a tubular part of a bicycle in the manner described above, and fix it there using the lever mechanism (20). During normal use (i.e. when the user is cycling), the device may be used as a bicycle light in the conventional manner. However, when it is required to utilise the device as an anti-theft device, the user presses the "arm" button on the fob. This activates the motion sensor alarm function, and also causes the solenoid latching mechanism to lock the two housing sections 12, 14 together. Thus, the device cannot be easily removed from the bicycle, and assists also in preventing theft of the unit itself. Whilst armed, any unauthorised movement of the bicycle will cause the siren to sound. If a thief is riding the bicycle, it is thought that the continuous sounding of the siren in their direction will discourage any further attempt to steal the bicycle and will, in any event, alert passers by and draw attention to the theft. When the authorised user returns to the bicycle, they can disarm the motion sensor alarm circuit, which additionally causes the solenoid latching mechanism to move to the "unlocked" position described above. Thus, the device can once again be used as a conventional bicycle light or, if the user wishes to, they can remove the device from the bicycle. As stated above, the fob may have an additional "panic button" which the authorised user can press, when they are within range of the device, to cause the siren to sound in the event that they feel threatened or otherwise wish to draw attention to themselves in the case of an emergency.

Thus, aspects of the invention provide a single device which serves two functions, thus as a front bicycle light to illuminate the road in the dark, with the additional security of an alarm system to reduce the risk of theft of either the bicycle or the light unit itself. It will be appreciated that, individually, the light circuit configuration and the alarm circuit configuration may take different forms, and the present invention is not necessarily intended to be limited in this regard. It is thought that a person skilled in the art will be able to design and realise a suitable electronics module to fulfil the desired functions according to specific design requirements.

The vehicle has been described above as a bicycle, however the invention can be easily adapted for use with other vehicles. Examples of such vehicles include, but are not limited to, strollers, scooters, wheelchairs and more. The light unit provides the bicycle with a common bicycle accessory often used by cyclists, however it will be understood by those skilled in the art that the device may be adapted such that the accessory attachable to the alarm unit may include other accessories, including, but not limited to, GPS devices and GPS device mounting devices, fitness monitors, drinks holders, and more.

It will be appreciated by a person skilled in the art, from the foregoing description, that modifications and variations can be made to the described embodiments without departing from the scope of the invention as defined by the appended claims.