AU721307B2 - Home security system for detecting an intrusion into a monitored area by an infrared detector - Google Patents

Description

1- P/00/0011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant: Actual Inventor: Address for service in Australia: DEVAN DOCKERY As Above CARTER SMITH BEADLE 2 Railway Parade Camberwell Victoria 3124 Australia Invention Title: HOME SECURITY SYSTEM FOR DETECTING AN INTRUSION INTO A MONITORED AREA BY AN INFRARED DETECTOR The following statement is a full description of this invention, including the best method of performing it known to us 1A HOME SECURITY SYSTEM FOR DETECTING AN INTRUSION INTO A MONITORED AREA BY AN INFRARED DETECTOR Field of the Invention The present invention relates to a home security system and in particular a home security system which detects an intrusion in a monitored area with an infrared detector and includes a transmitter which transmits a time related radio signal to a portable receiver in the possession of the homeowner.

Description of the Prior Art A simple method of sensing an intrusion electronically is via infrared detection. Varying levels of infrared radiation are monitored either actively, by first emitting IR and then evaluating the reflected signal, or passively, by only receiving the infrared frequencies radiating in the monitored area. Once a variation has been detected, the system must communicate the state of alarm.

see Several security systems employ telephone lines as a means to alert authorities, 15 while other methods rely on door or window switches to trigger an alarm.

These systems are both costly and difficult to install. Furthermore, if the homeowner is neither accessible by phone nor within sight of his home, he cannot be prevented from encountering the intruder while the intruder is still on the premises. If the homeowner could be made aware of the intrusion and how long ago the intrusion occurred, he could decide whether or not he should enter his home.

The present invention provides means for passively sensing an intrusion, and transmitting the signal to a portable receiver in the homeowner's possession.

2 The signal transmitted to the portable receiver being coded to reference the time of intrusion to the present time.

Although prior art alludes to these aspects of a security system, the three have not been effectively combined to warm the homeowner that an intrusion has occurred within a certain time frame, independent of external circuitry or phone lines.

An infrared intrusion detector which transmits to a portable receiver alerting a security officer and triggering a visual alarm is disclosed in U.S.

Patent No. 4,797,657 issued January 10, 1989 to Vorzimmer et al. Unlike the present invention, the device taught by Vorzimmer et al. contains no mechanism which provides a reference as to when the intrusion took place. Although the theory of transmitting a radio signal to a remote portable receiver is also used in the present invention, the purpose of transmission in the system taught by S.Vorzimmer et al. is to notify security personnel as soon as possible that an 15 intrusion is currently in progress. It is not necessarily desirable for security personnel to be aware than an intrusion occurred at least thirty minutes ago.

The invention discussed in U.S. Patent No. 4,868,543 to Binkley, S• however, does implement a timer to control the power supply to an infrared mail oo..oi sensing device. The timer is actuated by a closed switch physically connected 00 20 to the mailbox door and by the detection of reflected IR waves. The timer of the present invention is not activated by either of these means. Whereas the Binkley device relies on the generation, reflection and reception of IR waves, 3 the present invention merely receives changes in the temperature resulting from body heat caused by movement of a person into the view of the detector lens.

No external wiring for door or window switches is necessary to activate the present device.

SUMMARY OF THE INVENTION The invention senses an intrusion by the reception of abrupt changes in IR levels as sensed by an IR receiving diode. Once the intrusion has been detected, an SCR triggered by the IR receiving diode supplies electrical energy activating a transmitter and a timer. The transmitter remains activated until the SCR is manually reset. The timer, in turn, supplies electrical power to a blinker circuit which modulates the RF (radio) signal being generated by the transmitter for a pre-set time. After this time has elapsed, the output of the blinker circuit ceases terminating the modulation of the RF signal while the SCR continues to power the transmitter. The output of the transmitter modulated by the blinker 15 is displayed for the pre-set time on a portable receiver device. This signal indicates that the system detected an intrusion within a fixed period of time, o: such as within the last thirty minutes. Subsequently, a steady signal is displayed on the portable receiver device. This steady signal indicates that an intrusion was detected at least thirty minutes ago. The system also provides means for 20 coding the transmitted radio signal for exclusive reception by the portable receiving device. In addition, a timer delay circuit is incorporated into the 4 security system which allows a homeowner enough time to activate the system and exit the area without triggering an alarm.

BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of the present invention will be had upon reference to the following detailed description when read in conjunction with the accompanying drawing which is a block diagram view illustrating a preferred embodiment of the present invention.

Figure 1 is a block diagram of the intrusion detector device.

Figure 2 is a block diagram of the portable receiver device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE PRESENT INVENTION With reference to the Figures 1 and 2, a preferred embodiment of the present invention is illustrated and comprises an intrusion detector device 10 and V a portable receiving device 50. Furthermore, as shown in Figure 1 each S• 15 intrusion detector device 10 includes an intrusion sensor 12 which is adapted to sense a variation in the emissions of infrared radiation in a monitored area. The i: intrusion sensor 12 is electrically connected to an SCR 16 through a delay timer,

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14. Upon setting the intrusion detector device 10 to monitor the area, the delay timer 14 delays the activation of the intrusion detector device 10 by the intrusion 20 detector 12 for a preset time.

9 o• Electrical power may be received from a conventional household electrical outletby means of electrical wall plug 30, transformer 32 and voltage control circuit 34. The output of the voltage control circuit 34 is applied 5 directly to the intrusion detector 12, delay timer 14 and SCR 16. Alternately the electrical power may be received from a battery 36. The intrusion sensor 12 generates an intrusion signal in response to a variation in infrared emissions in the monitored area after the delay timer 14 times out. The intrusion signal latches the SCR 16 to a conductive state. The SCR 16 remains in the conductive state until it receives a reset signal from the SCR/timer reset circuit Furthermore, when the SCR 16 is latched on, a timer 18, electrically connected to a modulation or blinker circuit 22 is started. The timer 18 activates the blinker circuit 22 for a predetermined period of time after being activated.

The output signal of the blinker circuit 22 is connected as a modulation input signal to the transmitter 24 which generates a radio signal transmitted via antenna 26. The output of the blinker circuit 22 is a time dependant intermittent signal which modulates the radio signals generated by the transmitter 24. The SCR 16 provides electrical power to the transmitter 24 which continues to 15 transmit steadily until physically reset via the SCR/timer reset circuit The SCR/timer reset circuit 20 can be activated by manually latching on an external switch (not shown) on the intrusion detector device 10. The SCR/timer reset circuit 20 resets the SCR 16, the timer 18, and the timer delay 14.

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o ~20 Furthermore, the transmitter 24 is connected to a transmitter code selection 28 circuit which digitally codes the signal for reception by the receiver antenna 56.

6 The hand-held receiving device 50 shown in Figure 2 has a receiver 54, a receiver antenna 56, a receiver code selection 52 circuit, and an alarm indicator display 58. It operates remote from the transmitting device 10 on its own power supply. Typically, this power supply would be a battery 60. The receiver code selection 52 circuit is programmed to selectively receive the coded signal from the transmitter 24 of the intrusion device 10. The alarm indicator display 58, is electrically connected to the receiver circuit 54 generates a visual display in response to the signals received from the receiver 54 in response to the radio signals transmitted by transmitter 24.

When the transmitted radio signal is being modulated by the output of the blinker circuit 22 the alarm indicator 58 displays an intermittent or blinking visual signal, produced by a blinking light source such as a light emitting diode.

9o* This intermittent or blinking visual signal informs the homeowner that an 9** intrusion has occurred within the time which was preset into the timer 18. If the So: 15 transmitted signal is not modulated by the blinker circuit 22, then the alarm Sindicator 58 displays a constant visual signal preferably, in the form of a S: constantly lighted light emitting diode. This constant visual signal notifies the homeowner that an intrusion had occurred at a time prior to the time duration 9..

which is preset into the timer. The period of time the blinker circuit 22 is activated by the timer 18 enables an approximation of the time relative to the current time when the intrusion occurred so as to warm the homeowner of the possibility that the intruder may still be in the home. For example, if the visual 7 display is blinking, less than 30 minutes have elapsed since an intrusion was detected.

From the foregoing, it can be seen that the present invention provides a simple, inexpensive, and yet wholly effective system for detecting an intrusion as well as providing a warning to the homeowner of a potential encounter with an intruder if the visual signal displayed by the portable receiver is a blinking signal.

Having described my invention, however, many modifications thereto will become apparent to those skilled in the art to which it pertains without deviation from the spirit of the invention as defined by the scope of the appended claims.

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Claims (3)

13. The security system of claim 12 further comprising a reset means 2 for manually resetting said means for modulating, said time delay means and °3 said SCR after the occurrence of an intrusion. *oSo

14. A home security system comprising 11 2 a free-standing intrusion detector to be set in an area to be protected 3 which when activated will initiate an alarm sequence, said intrusion detector 4 having intrusion detector means for detecting an intrusion, transmitter means for transmitting a radio signal in response to said intrusion detection, and timing 6 means activated by said intrusion detector means, said timing means including 7 means for modulating said radio signal transmitted by said transmitter means to 8 produce a modulated radio signal for a preselected period of time after said 9 intrusion detector detects an intrusion; and a portable receiver adapted to be hand carried by a home owner, said 11 portable receiver responsive to said modulated radio signal to generate a first 12 visual signal and responsive to said transmitter means transmitting after said 13 preselected period of time to generate a second visual signal. 00 1 15. The home security system of claim 14 wherein said means for S• 2 modulating is a blinker circuit producing an intermittent signal and said 3 modulated radio signal is a time dependent intermittent radio signal. 0 0: *i 1 16. The home security system of claim 15 wherein said first visual 2 signal is a blinking visual signal and said second visual signal is a continuous 3 signal. 12 1 17. The home security system of claim 14 wherein said intrusion 2 detector further includes a battery connected to said intrusion detector means and 3 a switch responsive to said intrusion detector means detecting an intrusion to 4 connect said battery to said transmitter means and said timing means. 1 18. The home security system of claim 17 wherein said intrusion 2 detector means is an infrared detector. 1 19. The home security system of claim 17 wherein said intrusion 2 detector includes delay means for delaying the activation of said intrusion 3 detector for a predetermined time after setting said intrusion detector to detect 4 an intrusion to allow the home owner sufficient to exit said area to be *o 5 monitored. ooo o

20. A security system substantially as hereinbefore described with reference to the accompanying drawings incorporating any one or more of the novel features herein disclosed. 08 DATED: 20 September 1996 CARTER SMITH BEADLE Patent Attorneys for the Applicant: DEVAN DOCKERY