2358427 AUTOMATIC LOCKING SYSTEM The present invention relates to an
automatic locking system and may be conveniently employed for automatically locking vehicle doors, but is not limited thereto.
A remote control device is often used for both locking a vehicle's doors and for activating the vehicle's alarm system. This remote control device is often located in a key fob. A problem with any locking system is to ensure that the system is operated at the appropriate time. For example when the driver leaves the vehicle it is possible to leave the vehicle unlocked because the driver has to remember to activate the locking system. Therefore it would be advantageous to provide a system whereby the locking system is operated automatically without the need for positive driver intervention.
According to the present invention there is provided an automatic locking system comprising first means located in the apparatus to be locked, and second means arranged to be portable enabling said second means to be transported away from said first means, characterised in that said second means is arranged to be activated when transported away from said first means, said second means including means for generating and transmitting a signal upon activation back to said first means which upon reception of said signal causes a locking mechanism within said first means to be operated.
According to an aspect of the invention, the apparatus may be a vehicle.
The first means may be located m the vehicle.
The second means may be located in a remote control device of t -ie vehicle's ignition.
The first means may comprise a receive antenna, a receiver circuit i qd processing means for generating an output signal to operate said locking mechanism.
The second means may comprise a transmit antenna, a transmitter cir4 it, and processing means for generating the signal.
In one embodiment of the invention a modified remote control dei -e transmitter in the 433MHz band could be integrated with the ignition key itsAlf so that as the driver removes the key from the lock the remote control devi e would start to transmit a series of messages intermittently. As the driver wl ks away from the vehicle, the vehicle based remote control device receiver fit would monitor the signal level. When the driver reaches a certain distance aw iy from the vehicle and the signal had dropped by a certain proportion, the d(rs would automatically be locked. Unlocking would be manually achieved, l 1 Or example, by pressing a button on the remote control device.
The intermittent signals may. be transmitted for a time penod long enou yh to account for the amount of time a typical driver takes to leave the vehilc.e.
This time may be minimised to conserve battery life.
In an alternative embodiment, the messages could be continually sent once the driver removes the ignition key. This would cope with delays in driver leaving vehicle. The remote control device could be recharged whilst in the ignition key slot. Once the internal battery voltage has dropped to a predetermined limit, the remote control device may transmit a battery low message to the vehicle a number of times, after which the vehicle would not lock but the vehicle may indicate to the driver by flashing the car lights, for example, that auto-locking will not happen.
In another embodiment the remote control device could also include an ultrasonic receiver. In this case, the vehicle would transmit ultrasonic messages at regular intervals which are received by the remote control device. When the remote control device ceased to receive the ultrasonic messages, for example when the vehicle doors close, it would respond by sending a lock signal to the vehicle. The vehicle would turn on the ultrasonic pulses when the driver removes the key from the ignition.
In yet another embodiment the vehicle could be equipped with a magnetic loop transmitter such as those found in door access systems. Energy is absorbed by a remote control device and used to send a radio or magnetic signal back to the vehicle to make known its presence. As the remote control device is removed from the vehicle, the energy received by the remote control device collapses, and therefore it cannot respond. The vehicle locking system would automatically lock when it stops detecting the received messages. Unlock ng would be by means of a standard radio technique. The most effiplient implementation for autolocking would be to have a remote control device with a magnetic receiver to absorb energy and a radio transmitter which usesAhat 5 energy to respond.
All the above remote control devices could include a switch to inh bit auto-locking by the driver. This would allow the vehicle to be left op!t if required.
Various embodiments of the present invention will now be describox in detail with reference to the accompanying drawings, in which:
Figure I shows the block diagram of the receiver processing equiptr ent located in for example, a vehicle, Figure 2 shows the processing circuitry which would be located in remote control device relating to the vehicle.
Referring to Figure 1, there is shown a receiver unit 2 to whiol. is connected a receive antenna 4. The output 3 of receiver unit 2 is connected o a processing circuit 6, which has an output 8. Output 8 is connected to the immobiliser and/or door lock circuitry of the vehicle. The receiver unit Ls a further output line 10, over which a received signal strength indicator (R.' SI) signal is passed to the processing circuit 6.
Referring to Figure 2, the remote control device incorporates a charging circuitry 20 having an input line 22. The input line 22 receives a charging current. An output line 24 of the charging circuit 20, is connected to one side of a memory storage capacitor or battery 26, the other side of which is connected to earth. The output line 24 of the charging circuitry 20 is also connected to an input of a voltage low detector 28 and to an input of a supply changeover switch 30. The output of the voltage low detector 28 is connected to an input of a processing circuit 32, the output of which is connected to an input of a transmitter circuit 34. The output the transmitter circuit 34 is connected to a transmit antenna 36. The supply changeover switch is connected to a remote control device battery 38, the other side of which is connected to earth. The input of the supply changeover switch is also connected to one side of a manually operated switch 40, the other side of which is connected to an output of the supply changeover switch 30.
The embodiment shown in Figures I and 2 involves minimal cost and uses radio means for communication. In Figure 2, as mentioned above, the rechargeable battery 26 could be replaced by a memory storage capacitor which typically could be one Farad in ca pacitance. The recharging mechanism in the form of circuitry 20 can charge the capacitor 26 by either by direct wired twelve volt connection made as the key is pushed into the ignition switch or via a magnetic coupling. The magnetic coupling may comprise two halves of a transformer. One of the halves could be in the remote control device and he other in side the ignition slot assembly of the vehicle.
To enable the apparatus to work under circumstances when: he rechargeable battery or memory storage capacitor 26 falls below a predetermined level, a voltage low detector 28 is provided which indicates to the user via an audible or visible signal that the memory storage capacitor or battery 26 is low. Under normal circumstances the processor is powered y a supply changeover switch 3 0 from the memory storage capacitor or battery:, ' 6. However, when the voltage low indicator is active, this indicates to the user by for example, causing the vehicle's horn to sound or lights to flash, that, he manual switch 40 should be operated so that the remote control device stand battery 38 is used to supply the processor 32. The processor 32 is arranged to provide the necessary series of signals which are transmitted via the transruiilter circuit 34 and the antenna 36.
The transmitted signals are received by the antenna 4 in the vehicle. Ae received signals are passed to the receiver 2 which in turn passes those signals to a processing circuit 6 which generates the required signals on output line 8 to activate the vehicle immobiliser and/or door locking circuitry.
The typical supply current for a 433MHz remote control device is 2p-A.
The range from such a device is no more than about 5 metres. The no ge requirement would need to be higher in order to provide reliable communications. Therefore, a current requirement of 1OmA plus an additional processor (assuming 5mA continuous for a processor), and assuming one message takes 85ms to send (similar to an existing remote control device), and assuming, one message is transmitted every 2 seconds then the average current which is required is:
Processor current + TX currentduty cycle =5 + 100.0425=5.5mA Assun-fing the use of a 0. IF capacitor and that it is charged to 5.5V before transmit and that the lowest operating voltage is 3.3V then the operating time will be:
dVC = 2.20. 1/5.5E-3=40 seconds, If a 1 F capacitor were used, the operating time would extended to over six minutes.
By making the locking logic dependent on the measurement of signal level reaching the vehicle receiver, it will be possible to ensure that the vehicle keys cannot be locked in the vehicle. If the key is left on the vehicle seat, the received signal level will not drop as the driver leaves the vehicle and the vehicle will remain unlocked.
The present invention is not lirnited to vehicles. It could also be used on personalised furniture, for example, desks which lock when the user leaves them, computer passwords whereby the computer logs out as the user leaves or switch in a screensaver password.