GB2355830A - Vehicle alarm system - Google Patents

Abstract

A system for warning of impact, collision, sudden braking or attempted break-in uses a G-sensor 2 to detect acceleration of a vehicle in both fore-and-aft and side-to-side directions. A switch 3 selects the use of signals corresponding to both directions when the vehicle is stationary, but only the fore-and-aft direction when the vehicle is moving. The sensitivity of the system is adjustable, and timers 5 allow setting of delay and duration of a warning signal. The alarm may be the vehicle hazard lights, the horn, or other flashing lights. There may be compensation when the vehicle is parked on a slope.

Description

2355830 Warning sVstems This invention is concerned with warning systems,

and relates in particular to such systems that can be used with motor vehicles to indicate either that the vehicle, when in motion, is braking rapidly or that, when stationary, it is being interfered with.

Motor vehicles - and especially motor cars - are very much a part of modern life, and considerable efforts are made to keep them and their occupants safe. One major area of safety concern - for a car's occupants, at least - is when the driver brakes hard and unexpectedly, as when effecting an emergency stop; all too often this can result in a following vehicle running into the car, with possibly disastrous and far-reaching consequences. Another area that gives cause for concern is that of theft, either of the car itself or of its contents. In some areas of the world a vehicle is stolen, or at the very least broken into, every minute of every day.

It would be useful were there to be some sort of alarm/warning system that could help prevent either of these occurrences, and it would be highly desirable if the same system could assist with both. The present invention proposes just such a warning and/or alarm system. More specifically, the invention suggests such a system - and particularly one that involves the vehicle's hazard warning light system (HWL-system) that both relates tothe vehicle's rapid deceleration (such as by the sudden, hard application of the vehicle's brakes) and also relates to the detection and 2 notification of the vandalism of the (stationary, parked) vehicle. By hard application of the brakes is meant the so-called panic braking involving the hard and sustained application of vehicle brakes in an emergency, which braking causes a rapid deceleration which entails a hazard for the traffic behind. By vandalism is meant collisions with, blows to and impacts on a parked vehicle. These cases are now further discussed.

Rear-end collisions During driving in dense urban traffic, and otherwise where driving is performed at high speeds, there is a greater than normal need for drivers to be able to react rapidly. However, many drivers are inattentive in precisely such situations because that sort of driving is often monotonous, and normally presents few challenges. Statistics show that accidents more often occur in such conditions, and in this connection rear-end collisions have become an increasing problem (pile-ups on motorways, in particular, often have fatal consequences). In this respect, it seems to be one part of the problem that drivers are too accustomed to seeing normal brake lights, and do not therefore react with sufficient speed, firmness and strength when confronted with panic braking ahead.

Another part of the problem is that the existing brake signals do not attract the attention of drivers behind. Possible. explanations may be that the brake lights/signals are not sufficiently visible, or that they are not powerful enough, or are not sufficiently distinguished from the other rear lights fitted to the vehicle. Although new types of brake lights may have 3 greater luminous power than previously, and are often placed in an elevated position, for example in the back window of the vehicle, in many cases this is insufficient to prevent rear-end collisions. One reason for this may be that ordinary brake lights are a warning notice of all kinds of braking, and that hazardous, hard and sustained panic braking is not shown in a way that distinguishes it from normal or gradual braking. For these reasons it has become the fashion, especially on the motorways in Europe, for drivers to use the manual switch to activate the vehicle's flashing warning lights as soon as they feel that there is the possibility of a rear-end collision - as, for instance, when they have been braking hard to avoid running into a hazard, such as a stationary car, on the road ahead, and wish to warn any vehicles behind them. The invention proposes a warning system that will do this automatically - that will sense sudden, severe deceleration and will then activate some warning, typically the vehicle's normal hazard warning lights.

Theft and vandalism A parked vehicle can be all too easily be subjected to an accidental collision or, and worse, to deliberate vandalism, such as a blow to the bodywork or the smashing of windows with the aim of breaking into the vehicle and stealing either it or any articles of value which are fitted to or lying loose inside it. In order to prevent theft from vehicles, as well as the theft of vehicles, new vehicles often come with alarm systems installed to monitor doors, bonnet and windows. The alarm systems may be an integrated part of the vehicle's overall electrical system, or may be sold as equipment 4 packages for subsequent installation by the vehicle owner. The systems usually activate both light and sound signals when the alarm is triggered, and either the alarm must be switched off manually or - and as is now often a legal requirement - it switches itself off after a pre-set time following its activation.

Whether an integral part or a retro-fit package, a vehicle alarm system is usually equipped with either contacts (switches) which are activated wen a door or the bonnet is opened, or with sensors, normally a microphone, which trigger the alarm signals when window glass is broken or when mechanical tools are used to break into the vehicle. Unfortunately, with alarm systems of this kind a car thief or burglar will usually be well into the criminal act before the alarm is triggered, and there is little likelihood that the theft can be prevented. In addition to having an ordinary alarm system, vehicles would therefore benefit from being fitted with a device which would warn of forced entry at the earliest possible stage (and with a brief alarm signal which is deactivated after a short period of time). The invention proposes a warning system that will do this.

More particularly, the invention proposes a warning system that will do both these jobs - that will, when the vehicle is moving, sense sudden, severe deceleration and will then activate some warning, typically the vehicle's normal hazard warning lights, and that will, when the vehicle is stationary, warn at the earliest possible stage of a blow such as might be involved in a forced entry. With such a warning system fitted - and it is envisaged in all types of engine-propelled vehicle as a supplement to the existing activation of signal and light systems with the aim of reducing or eliminating the risk of rear-end collisions and vandalism of, or theft fromf parked vehicles - drivers in vehicles following on behind one using the system receive an early warning of the panic braking of that one, while the owner of the vehicle so fitted is given notification of vandalism at an early stage.

In order to achieve the stated desiderata, it is proposed, in accordance with the present invention, that there be mounted on/in the vehicle a Gsensor operative to detect such G-forces as might be occasioned by a rearend collision, or by the impact of a brick or a metal bar (as someone tries to break into the vehicle) in two orthogonal directions (fore and aft, and side to side) and in response thereto to output a signal, and that there be provided a switch to select between the G-sensor's singleor dual-direction output and connect it to an adjustable alarm unit which in response triggers the operation of some appropriate alarm device (such as the vehicle's hazard warning lights and/or its horn). And, naturally, the arrangement's sensitivity may be adjusted to select an appropriate input level at which such triggering takes place, to select an appropriate delay after which such triggering takes place, and to select an appropriate duration of the warning actuation signal and thus of the initiated alarm.

In one aspect, therefore, the invention provides warning apparatus for indicating whether a vehicle is undergoing significant acceleration (or, of course, deceleration), as would be the case when the vehicle is subjected to sudden -braking or a severe shock as from an impact or blow, which apparatus comprises:

6 a G-sensor operative to detect such acceleration in two orthogonal directions (fore and aft, and side to side) and in response thereto to output a signal; a switch operative to select for onwards transmission between the G- sensor's single- or dual-direction output; and an adjustable alarm unit operative.to receive the G-sensor's output via the switch and in response thereto to trigger the output of a warning actuation signal to some appropriate alarm device (such as flashing lights, horns, etc), which unit may be adjusted to select an appropriate input sensitivity level at which such triggering takes place, to select an appropriate delay after which such triggering takes place, and to select an appropriate duration of the warning actuation signal and thus of the initiated alarm.

The invention provides warning apparatus for indicating whether a vehicle is being subjected to significant G-forces, as would be the case when suddenly braking or when receiving an impact or blow. The vehicles can be any sort of vehicle, though generally the apparatus is intended for a motor car or lorry (truck), and the apparatus can be an integral part of the vehicle or it can be added afterwards as part of a retro-fit. The "sudden braking" is primarily that sort of emergency, "panic" braking effected when the driver is desperately trying to avoid a collision, while the impact or blow is generally the sort of relatively small "shock" given the vehicle by someone trying to smash a window to break in.

7 The apparatus of the invention utilises a G-sensor operative to detect the relevant acceleration in two orthogonal directions (fore and aft, and side to side) and in response thereto to output a signal. This G-sensor may be of any type suitably sensitive and robust, and one such is that sold under the name LA02 Sensor by Pewatron AG of Zarich. A suitable sensitivity corresponds in general to a deceleration range of up to 20 M/S2, corresponding to a braking effect of up to 2G, but it may also be appropriate to use the invention with other values outside these ranges. In practice, it has been found that a preferred suitable value is up to about 8M/S2, corresponding to 0.8G.

Since a G-sensor is sensitive to its orientation and thus to the tilt of the vehicle in relation to the horizontal plane - a signal will be generated as a result of the gravitational force when the vehicle is driven on an incline or when it is in a non-horizontal parking place. Depending on the exact type of G-sensor, and upon how it has been installed, this may mean that the system is more sensitive when the vehicle is driven downhill and when it is parked on a downward slope. And similarly, in the opposite case, when the vehicle is driven uphill or is parked on an upward slope, the circuit may be less sensitive than when the vehicle is being driven or is parked on a horizontal plane. As the Gsensor is of the four-way type, the variation in the effect of the gravitational force, as described above, can be eliminated if, as is preferred in the invention, the device therefore measures both deceleration and acceleration at the same time. By using a differential amplifier the acceleration signal is subtracted from the deceleration signal; this'ensures that the gravitational 8 force, as represented by the signal, is always eliminated.

The invention's warning system employs a switch operative to select for onwards transmission between the G-sensor's single- or dual-direction output. The idea is that, when moving, only for-and-aft G-forces need be monitored (and indeed lateral G-forces, experienced when cornering hard, for example) may actually need to be ignored). The switch may be of any variety, and may either be manual - to be set or re-set by the driver depending on whether he is parked or driving - or (and preferably) automatic, determining by some test (such as whether the ignition is on, or the engine is running) that the vehicle is parked or not.

The warning system of the invention utilises an adjustable alarm unit operative to receive the G-sensor's output via the switch and in response thereto to trigger the output of a warning actuation signal to some appropriate alarm device. This alarm unit may be adjusted to select an appropriate input sensitivity level at which such triggering takes place, to select an appropriate delay after which such triggering takes place, and to select an appropriate duration of the warning actuation signal and thus of the initiated alarm. Each of these is now discussed in more detail.

Sensitivit An important aspect of the invention's system is that it is reliable and credible. Where false alarms occur frequently their warning effect is weakened, since the alarm effect may degenerate and be easily misinterpreted to mean, for example, that a driver has pressed the manual hazard warning light switch by mistake, or that, if the -vehicle is parked, the vehicle's light system is defective. The signal is only 9 activated if the vehicle suffers a significant G-force effect - for instance, if it decelerates so sharply that there is a risk of a rear-end collision. For this reason the level at which the signal is activated, the trigger level, is set at such a level that it only responds appropriately. Thus, where the vehicle is moving, it is set to a level appropriate to a sharp deceleration. Of course, obviously the trigger level should not be set at a higher level than the level which would apply for all vehicles with brakes of normal strength in such a deceleration situation. In practice, the limit would be in the range from O.S to 0.9G.

Where, however, the vehicle is parked, and the system is to detect vandalism, the sensitivity should be set at a lower trigger level (at the same time, of course, the G-sensor is re-coupled to provide a fourway, bidirectional response instead of a two-way, unidirectional response, so that the alarm signal is triggered whether the vehicle is vandalised from the front, the back or the sides). The four-way G-sens6r generates the same signal for each direction. The signal is proportional to the force on the G-sensor.

Timing - delay and duration In order to avoid situations where the brief application of brakes, or a momentary, single blow to a parked vehicle, triggers the relays and activates the associated warning, the alarm unit is fitted with a time delay, Tl, of up to about half a second (generally in the range O.OOS-O.S seconds). At the moment when sufficient deceleration or a blow due to vandalism is measured over a defined period, the signal is activated. Since, in such a situation, the vehicle may represent a hazard to the traffic beh.in d, or may be stolen, the signal should continue for a certain period of. time even - 10 if the deceleration or blows due to vandalism again fall below the trigger level. This second period of time, T2, should be one of a few seconds, usually less than ten (and typically in the range 3-8 seconds). At the end of the T2 period, the invention's system is (after a re-set) again ready to measure a new deceleration or act of vandalism, and again activate a new signal if the same conditions recur.

The adjustable alarm unit employed in the invention's warning system is operative to receive the G-sensor's output via the switch and in response thereto to trigger the output of a warning actuation signal to some appropriate alarm device which actually outputs an alarm. The alarm device is most preferably the vehicle's normal hazard warning lights system, as already installed in the vehicle. However, depending on the vehicle's electronic control system, among other things for controlling the light intermittency rate, the warning of hard braking or forced entry can be given with a higher light-intermittency rate. In practice, where vehicles have an electronic intermittent light circuit installed on the vehicle assembly line, this is done by connecting the signal from the invention to a special input (alarm input) on the vehicle's electronic intermittent light circuit.

In another version, the invention can also be connected to the motor horn to give a combined light and sound signal. Moreover, the invention can be used in vehicles without using the hazard or intermittent lights. In this case, separate light sources are fitted with special prominence - for example, in the form of a flashlight, strobe or pulsating light mounted to project the light backwards from the vehicle and/or on the roof of the vehicle. Here, the light may be orange/yellow or red, or a combination of these colours.

In yet another version, the alarm device could involve the establishment of a general radio link or other form of communication between vehicles. When using the invention it would then be possible to give a warning signal to vehicles at the back, and that signal could be used to trigger an alarm in those vehicles, the alarm being in the form of a light or sound, or in some other way, or in a combination of such ways. At the same time, it would also be possible to trigger the automatic braking of those vehicles.

Very preferably the warning system of the invention incorporates switch means by which its operation - and specifically its causing of a visible or audible alarm to be generated - can be overridden. Thus, if, for example, the system malfunctions, it can be manually shut off.

The warning system of the invention is most conveniently powered from the vehicle's own battery/ power system, although it could of course have its own, independent power supply.

One practical version of the invention consists of an electrical circuit with relay contacts which can withstand the effect of activation and deactivation of warning and flashing lights on a vehicle. The electrical circuit is powered by voltage from the vehicle's battery. The main components of the circuit are the relays and a- G-sensor which determines when the relays are to be activated. The electronic unit which controls the circuit is equipped to permit adjustment of the trigger levels, making it possible to activate the signal in response to varying degrees of force. The adjustments that can be made make it possible to set different levels, depending on how great the braking force is to be, or how much force may be applied to the vehicle under acts of vandalism, bef ore the relays are activated and the hazard warning lights and flashing lights start to operate. The electronic unit is also fitted with an adjustable time delay, so that braking or vandalism must take place for a certain period of time before the signal is activated. The duration of the signal can also be adjusted.

The invention can be supplied both as an easily installed accessory and as standard equipment fitted to new vehicles during factory assembly. One version of the invention is effective within the deceleration range 0-20 m/s2, corresponding to a braking effect of 0-2G, but it may also be appropriate to use the invention with other values outside these ranges. In practice, it has been found that a suitable value for the trigger level is up to about 8M/S2, corresponding to 0.8G.

The main, and preferred, features of the warning system of the invention may conveniently be summarised as follows:- 1. The system utilises a G-sensor fitted within the vehicle to detect hard acceleration or the impact of sudden blows.

2. The G-sensor is a four-way sensor, detecting both fore-and-aft and side-to-side acceleration.

3. The G-sensor is 'connected to a differential amplifier to eliminate the effects of normal gravitational force.

4. The system activates the vehicle's own hazard warning lights, possibly at a higher-than-normal intermittency rate, overriding their own system to do so.

5. The hazard warning signal is activated only after the G-sensor's output signal has exceeded the pre-set minimum level for a pre-set minimum period of time.

i - 14 An embodiment of the invention is now described, though by way of illustration only, with reference to the accompanying diagrammatic Drawings in which:

Figure 1 shows a block diagram of a warning system according to the invention; Figure 2 shows a timing diagram for the warning system of Figure 1; and; Figure 3 shows a circuit diagram for the warning system of Figure 1.

Figure 1 is a block diagram of one embodiment of the warning system of the invention, with its associated related power source (the battery of the vehicle in which the system is employed) and signal light (the vehicle's hazard warning light system).

Briefly, a G-sensor (2) outputs to a trigger (4) which passes a trigger signal through a timer (5), output buffer (6) and override switch (7) to the vehicle's own hazard warning lights system.

A voltage transformer (1) converts the vehicle's battery voltage to the operating voltage used by the invention, and which in this embodiment is 5 volts. The G-sensor 2 is used to give the signal to measure the deceleration rate of the vehicle when moving, and the kinetic forces to which the vehicle when parked may be exposed. The sensor has a measurement range of 2G, corresponding to 20M/S2. The G-sensor 2 is of the so- called four-way type, which registers the acceleration force in four directions on the same plane.

The switch 3 is used when the vehicle is to be parked. In this position that is, when so parked the G-sensor 2 is activated such that it registers the acceleration forces on all four sides of the vehicle, while at the same time the sensitivity of the trigger circuit 4 is increased.

The trigger circuit 4 - for example, one of the so-called Schmidt trigger type - compares the output voltage from the G-sensor 2 with a given reference voltage, where the latter defines the limit before signal activation.

The timer circuit 5 consists of two circuits for time-setting. Timer I sets the time delay TI which prevents very brief braking or blows to the vehicle from giving hazard warning signals. TI should be in the range between 0.005 and 0.5 seconds. Timer 1 can be constructed using an oscillator, a counting circuit and some logic circuits.

Timer 2 deals with duration, T2. At the moment a sufficiently-powerful deceleration has been measured over a desired period, the hazard warning signal is activated. This signal is a warning that there is a risk of a rear-end collision or vandalism, and it should therefore continue for certain period of time. Timer 2 determines the length of this period, and can be constructed applying the same principles as those used for Timer 1.

The output buffer 6 operates different signal sources, both internal and external. The output signals, marked B, are signals that can set a higher intermittency rate for the hazard warning and - 16 intermittent lights, or may be connected to other alarm systems.

The override switch 7 consists of one or more relay which overrides the controls of, and so activate, the vehicle's hazard warning lights and intermittent lights. The relay's contacts should be able to withstand 2030 A and be connected as voltage-free contacts.

Figure 2 shows a signal timing diagram for an alarm cycle where VH is the so-called panic voltage, VT is the trigger voltage, and Vs is the Gsensor's output voltage. The hazard warning signal has been drawn in a separate coordinate system, and dotted lines have been drawn to mark the events which entail a changed alarm state. It is important to note that TI starts when Vs crosses VT + 12VH, and that this time continues by itself, even if Vs falls below VT, but not below VT-12VH. The hazard warning signal continues until T2 has expired.

Figure 3 shows a more detailed, component- level, circuit diagram for a warning system of the invention as shown in block form in Figure 1. It needs no additional comment at this time.

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Claims (12)

Claims

1. Warning apparatus for indicating whether a vehicle is undergoing significant acceleration (or, of course, deceleration), as would be the case when the vehicle is subjected to sudden braking or a severe shock as from an impact or blow, which apparatus comprises:

a G-sensor operative to detect such acceleration in two orthogonal directions (fore and aft, and side to side) and in response thereto to output a signal; a switch operative to select for onwards transmission between the G- sensor's single- or dual-direction output; and an adjustable alarm unit operative to receive the G-sensor's output via the switch and in response thereto to trigger the output of a warning actuation signal to some appropriate alarm device (such as flashing lights, horns, etc), which unit may be adjusted to select an appropriate input sensitivity level at which such triggering takes place, to select an appropriate delay after which such triggering takes place, and to select an appropriate duration of the warning actuation signal and thus of the initiated alarm.

2. Apparatus as claimed in Claim 1, wherein the G-sensor is of a sensitivity corresponding to a deceleration range of up to 20 M/S2, corresponding to a braking effect of up to 2G.

3. Apparatus as claimed in either of the preceding Claims, wherein, the Gsensor being sensitive to its orientation, the variation in the effect of gravitational force is eliminated by the device measuring both deceleration and acceleration at the same time, and incorporating a differential amplifier to subtract the acceleration signal from the deceleration signal.

4.- Apparatus as claimed in any of the preceding Claims, wherein the switch operative to select for onwards transmission between the Gsensor's single- or dual-direction output is automatically set and re-set in dependence of the vehicle's status.

5. Apparatus as claimed in any of the preceding Claims, wherein the adjustable alarm unit, operative to receive the G-sensor I s output via the switch and in response thereto to trigger the output of a warning actuation signal to some appropriate alarm device, is when the vehicle is moving - adjusted to operate when experiencing an acceleration in the range from 0.5 to 0.9G.

6. Apparatus as claimed in any of the preceding Claims, wherein the adjustable alarm unit is - when the I vehicle is stationary - adjusted to operate when experiencing an acceleration of less than 0.5G.

7. Apparatus as claimed in any of the preceding Claims, wherein the adjustable alarm unit is fitted with a first time delay, Tl, of up to half a second, and upon activation the signal persists for a second period of time, T2, of up to 10 seconds ten, whereupon the system is, after a re-set, again ready.

8. Apparatus as claimed in any of the preceding Claims, wherein the alarm device is the vehicle's horn and/or the vehicle's normal hazard warning lights system.

9. Apparatus as claimed in Claim 8, wherein when used with a vehicle having an electronic intermittent light circuit this is connected to and driven by the alarm system's signal at a higher than normal rate.

10. Apparatus as claimed in any of the preceding Claims, wherein there is incorporated switch means by which its operation - and specifically its causing of a visible or audible alarm to be generated - can be overridden.

1I.Apparatus as claimed in any of the preceding Claims which is powered from the vehicle's own battery/power system.

12.Apparatus as claimed in any of the preceding Claims and substantially as described hereinbefore.