GB2368440A

GB2368440A - Car security alarm sensing battery voltage change

Info

Publication number: GB2368440A
Application number: GB0114683A
Authority: GB
Inventors: Jr Robert R Keller; Matthew C Stephan; Dilip Patel; Eric A Templeton
Original assignee: Chamberlain Group Inc
Current assignee: Chamberlain Group Inc
Priority date: 2000-06-16
Filing date: 2001-06-15
Publication date: 2002-05-01
Also published as: FR2811116A1; DE10128891A1; CA2350677A1; AU5197801A; GB0114683D0

Abstract

A vehicle security system can be armed or disarmed by an authorised user who is alerted if the alarm system is armed prior to the use of the vehicle. The warning that the alarm is armed is triggered by sensing a change in the vehicles' battery indicating entry to the vehicle. A piezoelectric vibrations sensor may be a part of the sensing system able to detect a running engine or able to generate warning sounds. The system preferably uses a comparator and capacitor to detect changes in the battery 121 voltage. The voltage comparator circuitry 111 or substantial parts of the alarm system may be contained within the battery housing 153.

Description

2368440 USER ALERTING METHOD AND APPARATUS FOR USE WITH SECURITY SYSTEMS

Background of the Invention

The present invention relates to electrical security systems and more particularly, to such systems which alert users to the armed state of the security system.

Security systems are in common use in many environments today Any property such as homes and automobiles may include a security system which, when placed in the ready or armed state, generates flashing lights, bells, sirens, silent calls to security personnel or other activity intended to stop the unauthorized use of the thing protected While such systems reduce unauthorized use, they may sometimes surprise an authorized user who has failed to take appropriate steps to show the authorized nature of his or her use by disarming the system before the security features become operative.

In the case of automobile security systems a user normally arms the security system when leaving the automobile so that the alarm conditions will occur should an intruder try to start or otherwise use the automobile When the user returns to the automobile, he or she disarms the security system by the use of apparatus and procedures known only to the user before attempting to make use of the vehicle Sometimes, however, the authorized user forgets to disarm the security system and is greeted with the alarm conditions when making use of the vehicle with an armed security system.

In order to reduce the "forgetfulness" of users, some systems include arrangements for alerting potential users to the armed state of a security system Prior such alerting systems in automobiles generally involve the wiring of seats with special switches or the attachment of sensors to existing switches to detect the presence of someone in the vehicle If a person is detected and the security system is armed, a special alerting activity is generated The alerting activity, which may be the playing of an alert tone, is intended to remind the authorized user to disarm the security system before trying to start the car On the other hand, a knowledgeable unauthorized user who cannot disarm the security system may be convinced by the alerting activity to leave the vehicle or face the consequences of the sirens and flashing lights of a triggered security system.

A problem exists with such alerting systems in that special switches and sensors must be mounted in the vehicle and connected to the security system This can add greatly to the complexity and expense of an installed security system Further, security systems are more and more being associated with small parts of an overall item being protected For exampie, a radio may include a security system for its protection 25 may the automobile's main battery When a person has an item such as a secured radio or battery installed in his or her car, that person does not want the added expense and potential for reliability failure, of additional sensors and switches being mounted in places other than the radio or battery Accordingly, a problem exists in the identification of users present in secured automobiles.

Summary of the Invention

The problem is solved and an advance is achieved in accordance with the present invention An alarm system having a source of electrical power which is also used by a user for other purposes includes a detector connected to the power source A use of power from the power source by the user is detected and a notifying apparatus generates an alerting signal to warn the user that the security system may need to be disarmed before further use is undertaken.

In the case of an automobile security system, the main starting or primary battery is the source of electrical power A voltage detector surveys the voltage output of the battery and when the voltage level drops, such as is caused when a potential driver opens the door and the overhead light turns on, a signal is sent to a controller of the security system The is controller responds to the signal by generating an alerting signal, such as a tone, to warn the potential driver that the security system may need to be disarmed.

In accordance with an embodiment, the security system has an armed and unarmed state and the controller causes the alerting signal in response to the detected voltage signal only when the security system is armed.

Additionally, the controller may comprise a microprocessor and the detected voltage signal is applied to an interrupt input of the microprocessor to immediately initiate a response.

In an advantageous embodiment, the entire security system may be incorporated into an automobile attachment such as a primary battery or a radio When the system is used with the primary battery of an automobile, the potential driver detector (the voltage sensor) remains inside the battery case and senses the terminal voltage of the battery In this way the security system and the potential driver alerting system requires no connections to the automobile other than the normal connection to the positive and negative battery terminals.

The voltage change to be detected to identify a user or potent-al driver may be very small, on the order of about 5 millivolts The detector employed to sense such a small voltage change may employ an integrated circuit comparator in which the primary battery voltage is compared to a reference voltage When the primary voltage falls below the referenced voltage, a voltage detection signal will be applied to the security system controller The security system of the embodiments uses a piezoelectric device to detect vibrations of the automobile in order to provide indication that the engine is running Advantageously, the controller 7 drives the same piezoelectric device to generate warning tones such as the potential drive alerting signal.

Brief Description of the Drawings

The invention will be more readily understood from the following description when read in accordance with the drawing in which:

FIG 1 is a block diagram of a security system including an arrangement for alerting a potential user of the armed state of the security system; FIG 2 is a block diagram of a security system embodied in an automobile battery; FIG 3 is a circuit diagram of a voltage change detector; and FIG 4 is a circuit diagram of an arrangement for sensing vibration and for producing an alerting tone.

Description

FIG 1 is a block diagram of an embodiment of the invention The embodiment includes an controller 101 which may comprise a programmed microprocessor or a custom application specific integrated circuit The exact nature of the controller which carries out the process described herein is not critical The controller 101 may represent a portion of the processing capability of apparatus which is providing other control functions The controller 101 receives various security system input signals and responds to them by generating control signals to be acted upon by various apparatus to perform the security function FIG 1 includes an antenna 107 for receiving security system controlling rf signals from a user operated transmitter 109 The rf signals are detected in a receiver 105 and the resulting detected signals are applied to controller 101 which interprets them Such rf transmitted signals include an arm signal to arm the security system and a disarm signal to disarm the security system The nature of rf transmission to convey signals and the detection of such signals are well known and not described herein In the present embodiment, the signals conveyed by the receiver to the controller 101 either place the security system in the armed or unarmed state.

In the unarmed state the controller need not be attentive to any of its input signals, except those from the receiver so that the armed state can be entered In the armed state the controller 101 receives input signals from alarm condition sensors 103 and person entry sensors 1; 1 and based on those input signals controls apparatus such as security functions 112 and alert signal source 115 When the security system of FIG 1 is being used with an automobile, the security sensors 103 may include an ignition pulsing electrical sensor, a battery charging voltage sensor and a vibration sensor, one or some combination of which may be used by controller 101 to identify whether the car has been started For example, if the system is armed and one or more of the sensors 103 indicate that the engine is running, controller 101 will, send a signal to security functions 113 to cause an alarm condition.

Security functions 113 may include apparatus to remove electrical power from the engine to stop it and noise producing and light flashing devices to ward off an intruder.

To protect an authorized user against starting the engine while the security system is armed, it is desirable to remind people who are in a position to start the car, i e, a potential driver, that the security system is armed The potential driver will then disarm the security system by sending the appropriate signal from transmitter 109 to the controller 101 via the antenna 107 and receiver 105.

The embodiment of FIG 1 includes a person entry sensor 111 which is used to detect a potential driver's entry into the automobile and provide a signal representing such to controller 101 When controller 101 receives a signal from person entry sensor 111 indicating a potential driver and the security system is in the armed state, controller 101 sends a signal to alert source 115 which generates a human detectable alert indication that the security system is armed and should be disarmed before the engine is started The potential driver will then respond to the alert indication and disarm the security system before starting the engine.

As shown in FIG 1, the person entry sensor 11, is connected to sense the voltage level of a voltage source 117, which source is also used to power other electrical equipment about the thing being protected It should be mentioned that other connections (not shown) may exist between the voltage source 117 and security equipment 101-115 to power the operation of the equipment In the automobile example, voltage source 117 may be the primary battery for powering starting, ignition and other functions such as lights, radio, blowers, etc.

FIG 1 includes a person activity device 119 which may be an automobile overhead light (dome light) and door switch combination as is well known When an automobile door is opened, a door switch completes a circuit from voltage source 117 to the dome light The on-rush of current to the dome light will cause a reduction in the voltage at the voltage source 117 The person entry sensor 111, by connection 118 to the voltage source 117, detects the reduction in voltage and transmits a signal to controller 101 Controller 101 responds to the signal from person entry sensor 111 by enabling the alert source 115 to notify the potential driver that the security system is armed when in fact it is If the:^- security system is disarmed, the controller 101 will not enable the alert source 115.

FIG 3 is a circuit diagram showing an embodiment of a person entry sensor 111 of the type shown in FIG.

1 The sensor 111 is used to detect changes in voltage output of an automobile battery 121 which represents the voltage source 117 of FIG 1 Such changes may be caused by an in-rush of current to a light bulb 123 via a door open switch 125 In the present embodiment, door open switch 125 and bulb 123 are the normal dome light equipment found in most automobiles today The positive voltage terminal of battery 121 is connected to a 5 volt voltage regulator 127 which provides voltage to a comparator 129 and to a reference circuit comprising resistors 131, 133, 135 and 137 The comparator 129 may, for example be created from a well known LM 2902 operational amplifier The positive input of comparator 129 is connected to the positive voltage of battery 121 by a capacitor 143 The 5 volt regulator 127 and resistors 131-137 cooperate to maintain the positive input of comparator 129 at approximately 2 38 V when the resistors are of the value shown and in the absence of changes of voltage input.

The negative input of the comparator 129 is maintained at aporoximately 2 36 V by operation of the resistors 131-137 and the 5 V regulator 127 A capacitor 141 is also connected between the negative comparator 129 input and ground Capacitor 141 retards changes in the voltage level at the negative input when the voltage output of battery 121 changes The exact values of the regulator 127 and resistors 131-137 are not critical, however, the biasing they provide should be such that, in the absence of changes in voltage at conductor 118, the positive input of comparator 129 is kept positive with respect to the negative input by an amount approximately equal to the minimum voltage charge which is to be detected In the present-example, reductions in voltage of 10 mv or more are readily detected.

Normally, comparator 129 exhibits a logic one output signal at conductor 145 When a potential driver opens the door of the automobile, door switch 125 closes causing current to flow through light bulb 123, reducing the voltage level on conductor 118 The reduction in voltage level is passed via capacitor 143 to the positive input of comparator 129 The voltage level of the negative input is maintained by capacitor 141 so that for a period of time, derived in part from the RC discharge of capacitor 141 and resistor 137, the voltage at the negative terminal exceeds the voltage at the positive terminal This reversal of voltage causes comparator 129 to generate a logic low output signal.

The reversal of output signal on conductor 145 from high to low is applied via resistor 147 to an interrupt input of controller 101 which responds immediately by checking the armed/disarmed state of the security system If the security system is disarmed no result signals are generated Alternatively, if the security system is armed when the interrupt input occurs, a signal is generated to alert the potential driver to disarm the security system.

FIG 2 represents an embodiment which is used within the sealed housing of the main battery source for an automobile The battery housing is represented by the rectangle 153 which includes a positive battery terminal 150 and a negative battery terminal 149 In common use, the negative terminal 149 will be connected to the automobile ground and the positive terminal is connected as the main power source The positive terminal will be connected to the starter motor via a starter switch (solenoid), to the alternator for charging the battery, and to the main power distribution block for powering the radio, fans, lights, etc.

As with the prior embodiments a security system is controlled by the controller 101 which can be armed and disarmed by rf signals received at an antenna 107 and receiver 105 The security functions 113 in the example of FIG 2 are connected between the positive terminal of the battery cells 121 and the positive terminal 150 of the battery The security functions include apparatus for opening the circuit between the battery cells 121 and the positive terminal 150 and for grounding the positive terminal 150 Thus, when the security functions are enabled, battery power is removed from the automobile and the grounding of the positive battery terminal shunts the alternator Without battery or alternator power, the engine (not shown) will not run.

The driver entry sensor 111 functions as above described with regard to FIG 3 to sense the voltage at conductor 118 which powers the positive terminal 150.

When the voltage on conductor 118 changes, as will happen with the on-rush of current to a dome light, a signal is sent from sensor 111 to controller 101 The controller 101 is interrupted by the signal from sensor 111 and, if the security system is armed, the controller - sends an output signal to the alert signaling apparatus to alert the potential driver that he or she must disarm the security system before starting the engine.

The embodiment shown in FIG 2 includes an alarm condition sensor 103 which, as previously discussed, detects vibrations, among other conditions, in order to signal the controller 101 that the engine has been started FIG 2 also includes an alert signal source which may emit one or more audible tones to alert a potential driver to disarm the security system FIG 4 represents an arrangement by which circuitry may be combined to both sense vibrations and to emit audible signals Such combination of functions is particularly advantageous when, as in FIG 2, the security system is confined to a small space such as an automobile battery.

FIG 4 includes a piezoelectric device 161 which is mounted inside battery 153 When the engine starts and mechanical vibration occurs, the voltage generated by the piezoelectric device 161 in response to the vibrations is conveyed to a vibration sensor 163 via a capacitor 165 and resistor 167 Vibration sensor 163 senses the received voltage and when it exceeds a predetermined amount, representing engine running vibrations, a signal is sent to controller 101 via conductor 169 to indicate that engine running vibrations have been sensed The signal-on conductor 169 is used by controller 101 along with other sensed signals, as discussed above, to identify whether security functions should be enabled.

Piezoelectric device 161 is also connected to one side of a transformer 171 via two reversed sense zener diodes 173 and 175 The second side of transformer 171 is connected in series with a positive voltage source 177 and the drain-source path of an FET driver 179 The gate of driver 179 is connected via a resistor 181 to the control 101 Whenever the control 101 determines that a potential driver should be alerted, a rapid series of signals is transmitted to the driver 179, resulting in a series of pulses being applied to piezoelectric device 161 via transformer 171 The piezoelectric device 161 responds to the series of pulses from transformer 171 by emitting an audible signal.

While there have been illustrated and described particular embodiments of the present invention, it will be appreciated that numerous changes and modifications will occur to those skilled in the art, and it is intended in the appended claims to cover all those changes and modifications which fall within the scope of the present invention.

Claims

CLAIMS:

1 An alarm system for use in an automobile having a battery comprising:

alarm apparatus having an armed state in which alarm conditions will be commenced in response to unauthorized use and an unarmed state; voltage detecting circuitry for detecting changes in a voltage output of the battery; and a controller responsive to the voltage detecting circuitry and the state of the alarm apparatus for generating an alerting signal when the alarm apparatus is in the armed state and a voltage change is detected by the voltage detecting circuitry.

2 An alarm system in accordance with claim 1 comprising apparatus for unarming the alarm apparatus.

3 An alarm system in accordance with claim lor 2, comprising a voltage regulator connected to a voltage source of the battery for providing electrical power to the voltage detecting circuit.

4 An alarm system in accordance with claim 1, 2 or 3 wherein the voltage detecting circuitry and the contr-ll-er are substantially sealed within a housing of the battery.

An alarm system in accordance with claim 4 wherein the alarm apparatus is substantially sealed within the housing of the battery.

6 An alarm system in accordance with claim 1 wherein the voltage detecting circuitry comprises a voltage comparator.

7 An alarm system in accordance with claim 6 wherein the voltage detecting circuit comprises a capacitor for temporarily maintaining a voltage level at an input to the comparator.

8 An alarm system in accordance with any preceding claim comprising a piezoelectric device connected to the alarm apparatus to sense vibration and connected to the controller for generation of the alerting signal.

9 An alarm system in accordance with any preceding claim wherein the voltage detecting circuit generates an output signal when the output voltage of the battery changes by an amount greater than about 5 millivolts.

An alarm system in accordance with any one of claims 1 to 8 wherein the voltage detecting circuitry generates an output signal in response to reductions in the voltage output of the battery.

11 An alarm system in accordance with claim 10 wherein the controller responds to the armed state of the alarm apparatus and the outpult signal for generating an alerting signal.

12 An alerting system for use in a security system comprising a source of electrical power for providing power in response to user interaction; detecting apparatus connected to the source of electrical power for producing a power usage signal indicative of the usage of electric power due to user interaction; and notifying apparatus responsive to the detecting apparatus for generating an alerting signal in response to the power usage signal.

14 - 13 An alarm system substantially as hereinbefore described with reference to the accompanying drawings.

14 An alerting system substantially as hereinbefore described with reference to the accompanying drawings.