Classifications

• • G—PHYSICS
  • G08—SIGNALLING
  • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
  • G08B25/00—Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems
  • G08B25/008—Alarm setting and unsetting, i.e. arming or disarming of the security system

Definitions

• This invention relates to locks and more particularly to an electro-magnetic lock.
• the invention will be described in relation to an electronic lock for setting and releasing vehicle burglar alarms, but, it is to be understood that the invention is not limited thereto so it may be employed in any situation where a lock is required.
• Radio frequency operated electronic locks suffer from a number of disadvantages not the least of which is that the code carried by the radio frequency signal could be recorded by an unauthorised third party, stationed some distance from the car, who could re-transmit the coded signal when the vehicle was unattended to de-activate the alarm.
• the receiver within the vehicle could be jammed by a signal from another transmitter operating at or near the same frequency.
• an electro ⁇ magnetic locking system having a digitally derived encoder transmitter and a decoder receiver, said encoder transmitter having circuit means adapted to generate a predetermined coded magnetic field and said decoder receiver having circuit means adapted to respond to the coded magnetic field radiated by the encoder receiver.
• the encoder transmitter (which constitutes an electronic key) includes a tuned circuit having an inductive portion adapted to radiate the alternating magnetic field, means for energising the tuned circuit and coder means adapted to trigger the energising means in accordance with pre-set data rates and codes.
• the decoder receiver (which constitutes an electronic lock) preferably includes means for coupling to and receiving the alternating magnetic signal, means to identify the correctness of that signal and means for processing the / correct magnetic signal.
• the electronic key or transmitter includes a digitally derived code pulse modulated circuit to activate an inductive transducer which is adapted to radiate the magnetic field.
• the electronic lock or receiver includes means for coupling to and receiving the pulse modulated magnetic signal, circuit means for demodulating the received signal and circuit means for identifying the correctness of the digitally derived code.
• an electronic switch is activated to control power to an application lock, an application locking mechanism or an application circuit.
• the decoder receiver may include time delay means adapted to render the signal processing means inoperative for ⁇ a pre-deterrained time whilst the identified-as-correct signal is being recieved.
• the electro-magnetic locking system of the invention may incorporate means for identifying valid key users so as to control access to authorised users and to restrict user
• the decoder receiver may incorporate an additional time delay to permit input signal processing to be rendered inactive for a pre-determined time upon receipt of an invalid input code or invalid user identification.
• Fig 1 is a schematic diagram of an encoder transmitter of an electro-magnetic lock according to one embodiment of the invention.
• Fig 2 is a schematic diagram of a decoder receiver for an electro-magnetic lock according to one embodiment of the invention.
• Fig 3 is a schematic diagram of an encoder transmitter, the electronic key, of an electro-magnetic lock, according to a second embodiment of the invention, and.
• Fig 4 is a schematic diagram of a decoder receiver, the electronic lock, for an electro ⁇ magnetic lock, according to a second embodiment of the invention.
• the encoder transmitter of the first embodiment includes a coder unit integrated circuit 10 to which is applied pre ⁇ determined data rates and codes 16.
• a light emitting diode 11 indicates that the encoder transmitter is ready for use.
• the coder unit 10 is coupled to an oscillator unit 12 which in turn is connected to a tuned circuit 13 having capacitive component 14 and inductive component 15.
• the oscillator unit 12 is triggered to energise the tuned circuit 13 so that the series of pulses radiated by the inductive component 15 is in accord with the data rate and code rate set by the coder unit 10.
• the pulsing alternating magnetic field radiated by the encoder transmitter is coupled magnetically to a tuned circuit 20 of the decoder receiver set to resonate on the same frequency.
• the tuned circuit 20 has capacitive component 21 and inductive component 22 which form a tank circuit that responds to the narrow band of the alternating magnetic field signal.
• the frequency of the incoming signal If the frequency of the incoming signal is correct, it will be amplified by the integrated unit 23 and the original data code will be recovered through the network formed by diode 24, resistance 25 and capacitor 26.
• the coded data is then fed to the decoder 27 which, if the code is correct and in accordance with its input 50, produces a signal at its output 28. When this occurs, a positive voltage is applied to an input of the integrated circuit 29 so rendering integrated circuit 29 inoperative.
• capacitor 30 changes to a pre ⁇ set voltage through diode 31. When this voltage has been -
• the utput 34 goes low to cause an alarm output signal to indicate that an attempted code break has occurred.
• Diode 32 is now forward biased and grounds the tuning circuit 20
• the time constant of the network formed by resistor 25 and capacitor 26 sets the number of corrupt codes prior to
• Capacitance 36 may be reduced or removed to reduce the period of valid transmission at output 37.
• the transmission time is set for 5 seconds and the lock-out time
• the magnetically coupled alternating field does not require an aerial and as no radio frequency carrier wave is used, a user licence is not required.
• Zup the range of the system is small, say, of the order of 5 centimetres..
• the coded signal will penetrate any non-ferrous solid such as the glass of a car window and the power requirements of the device are minimal.
• the preferred frequency band is in the range of 1 to 15 kilohertz but higher frequencies may be used.
• an identical word code may be used in another similar device. each of them will be immune from activation by the other. Furthermore, the invention discriminates against casual tampering to reduce the nuisance value of false alarms from other users.
• the alarm section of the lock will only respond for a predetermined period and only when the precise frequency is received. If, during this period, the correct code is received the alarm section will not respond and the lock will open. Thus, three components are required to operate the
• the encoder transmitter includes a digital encoding unit integrated circuit 110, to which is applied a predetermined digital code 116.
• the digital encoder unit 110 is coupled to a pulse n oscillator unit 112, which in turn is connected to an inductive load circuit 113.
• the pulse oscillator 112 is activated to energise the load circuit 113, so that the series of pulses radiated by the inductive component 113, is J- in accord with the data rate and data code as set by the digital coder unit 110.
• the pulsing magnetic field radiated by the encoder transmitter is coupled magnetically to the circuit component
• the incoming pulse modulated magnetic signal is amplified by the integrated circuit unit
• the coded data is then fed to the decoder unit 120, which if the code is correct in accordance with its own preset input code 121, produces a signal at its output 122.
• the time constant of the network formed by resistor 123 and capacitor 124 will determine the number of corrupt codes prior to raising the invalid operator alarm, whilst the time
• the coded signal will penetrate any non-ferrous solid such as glass, brick, cement, acrylic, and aluminium, but _ Q with reduced sensitivity.
• the pulse modulating frequency of the encoder transmitter is approximately 1.0 kHz, higher frequencies may be employed, but it is dependant upon the component values of output transducer 113 and input transducer 114.
• The-high j j frequencies may be employed however at the sacrifice of sensitivity.
• This electronic locking system may be applied to any system to which power may be applied either via mains l ⁇ - ⁇ operation or by battery power, where a key and a lock are required. Further, this electronic locking system may be applied to any application which requires operation by an identified and/or authorised user of another electronic or electrical circuit. 2 ⁇ Various modifications may be made to design and construction without departing from the scope and ambit of the invention.

Landscapes

• Engineering & Computer Science (AREA)
• Computer Security & Cryptography (AREA)
• Business, Economics & Management (AREA)
• Emergency Management (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Lock And Its Accessories (AREA)
• Burglar Alarm Systems (AREA)

Applications Claiming Priority (2)

Publications (2)

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• 1986
  • 1986-11-21 JP JP61506196A patent/JPS63501452A/ja active Pending
  • 1986-11-21 EP EP19860906732 patent/EP0245385A4/de not_active Withdrawn
  • 1986-11-21 WO PCT/AU1986/000358 patent/WO1987003403A1/en not_active Application Discontinuation
  • 1986-11-21 AU AU67308/87A patent/AU603782B2/en not_active Ceased

Non-Patent Citations (2)

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