GB2193939A - Vehicle protection apparatus - Google Patents

Abstract

The apparatus comprises an ultrasonic sensing system having tamper-proof sensitivity for the separate transmission/reception 12 and control apparatus 14, and likewise with the manual control key switch 16. Provision is made for encoded infra-red remote control and weatherproofing of the key switch 16. <IMAGE>

Description

SPECIFICATION Vehicle protection apparatus This invention relates to vehicle protection apparatus. Such apparatus is applicable to, for example, protecting cars against theft. The apparatus is also applicable to lorries, vans and most other kinds of vehicle.

Currently available vehicle protection apparatus falls short of requirements in several respects including the requirement for sensitivity to a range of unauthorised actions, and the need to provide means for countering attempts to inactivate the protection apparatus by a thief or intruder. There are other requirements also.

An object of the present invention is to provide improvements in one or more of these respects, or generally.

According to the invention there is provided vehicle protection apparatus comprising sensing means to sense an unauthorised action with respect to the vehicle, and manual control means to activate/inactivate the apparatus as required, the apparatus being arranged to actuate protection response means upon detection of an unauthorised action in relation to the vehicle, characterised in that the sensing means comprises ultrasonic signal transmission and reception means to be located, in use, in a first part of the vehicle such as the passenger or driver compartment or the goods compartment, the sensing means being responsive to changes caused by actions of an intruder such as opening a door or window or effecting a blow thereon, the apparatus further comprising control apparatus connected by electrical conductors to said sensing means and responsive to a signal therefrom to actuate said protection response means, the control apparatus being adapted to be located, in use, in a second part of the vehicle separate from said sensing means, for example in the engine compartment of the vehicle, said control apparatus comprising means to actuate said protection response means upon the occurrence of any electrical discontinuity in the electrical conductors connecting the control apparatus to the sensing means.

The manual control means may comprise switch means, for example actuated by a key or other means limiting actuation only to authorised persons, whereby the system is switched on and off. Associated with the manual control means there may be provided delay means whereby the apparatus permits a time delay to occur before actuting said protection response means. Preferably, provision is made for two distinct types of time delay, namely an exit time delay and an entry time delay. These time delays are to permit an authorised user of the vehicle to activate and inactivate the apparatus without the incovenience of actuating the protection response means. The exit time delay preferably operates to cause the control apparatus to ignore alarm signals generated by the sensing means for a predetermined time delay period after the system has been first activated by, for example, the key switch.In this way, the key switch can be located within the vehicle and the apparatus switched on before the user leaves the vehicle, the time delay covering the period while the vehicle doors are opened and closed etc.. A time delay of about ten seconds may be suitable for this purpose. However, a longer interval may be provided without seriously compromising vehicle safety since it is unlikely that this aspect of the operation of the system will affect any person other than authorised users of the vehicle.

The entry time delay is more critical. This time delay operates to provide a mere delay between detection, of an unauthorised action and actuation of the protection response means. Again, this is to permit the authorised user to enter the vehicle without actuating the response means. The authorised user enters the vehicle, thereby generates a signal by means of the sensing means which would otherwise cause the control apparatus to actuate the protection response means, but, before the end of the entry time delay period, the user inactivates the apparatus by means of the key switch or other manual control means. The apparatus does not ignore signals generated during the entry time delay period.

The length of that period is preferably between five seconds and thirty seconds. Probably, five seconds to fifteen seconds is about the optimum, with eight to twelve seconds for choice. This period determines the interval before, for example, an alarm sounds, and is of significance in relation to relatively casual thefts of articles from within a vehicle, rather than theft of the vehicle itself.

The protection response means may comprise a siren, means to cause the vehicle lights such as headlights to flash, means to disable the ignition system or other electrical systems of the vehicle required for propulsion, or indeed other apparatus providing a response suitable for vehicle protection. A siren may be built into the control apparatus in the engine compartment of the vehicle. Likewise, an external siren may be connected to the apparatus.

According to another aspect of the invention there is provided vehicle protection apparatus characterised by sensing means comprising ultrasonic signal transmission and reception means.

In an embodiment of the invention described below vehicle protection apparatus comprises two units. The first unit is a detection or sensing device to be located inside the vehicle, such as in the passenger compartment. This unit operates by sending and receiving an ultrasonic signal around the interior of the vehicle, and any break in the signal caused by movement such as doors opening, windows broken or struck will be sensed by the detection device which, after a ten second delay, will activate the rest of the syetm. The ten second delay is to enable an authorised person to switch off the system via a key switch installed in the vehicle. The detection units indicates an "on" condition by means of a flashing red light emitting diode (LED) on the front of the unit.

In the embodiment, the sensing or detection unit and the key switch are connected via cables to a control unit or interface unit located in the engine compartment of the vehicle. This latter unit is the second part of the system and is the part which controls the functions of the alarm system. Ten seconds after the detection unit sends an alarm condition signal to the interface unit the system will sound an electronic siren which is built into the interface unit and/or flash the headlamps of the vehicle, andor disconnect the ignition of the vehicle.

In addition to the cables joining the detection unit to the interface unit, there are four cables extending from the interface unit itself.

Two of these cables are connected to the battery, one to positive, one to negative. The remaining two are joined, one to the low tension lead from the coil and the other to one of the headlamp wires, both using a simple clip-on method.

Any attempt to interfere with, or damage the detection unit, or key switch, or the cable leading from them, for example by cutting or pulling, automatically activates the system. On the other hand, any rocking or motion of the vehicle caused by passing traffic or weather conditions will not activate the system since the detection unit is only concerned with the environment within the vehicle itself. Striking or breakage of doors or windows however constitutes a change of environment and will therefore activate the system.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows, diagrammatically, the sensing apparatus and control apparatus and key switch, together with electrical connections to the vehicle battery and other electrical systems of the vehicle; Figure 2 shows a circuit diagram of the sensing apparatus of Fig. 1; and Figure 3 shows a circuit diagram of the control apparatus of Fig. 1.

As shown in the drawings, vehicle protection apparatus (10) comprises sensing apparatus 12 to sense unauthorised action with respect to the vehicle, and control apparatus 14 connected by electrical conductors to the sensing apparatus 12 and responsive to a signal therefrom to actuate protection response means, for example a siren located in the control apparatus 14.

Manual control means 16 in the form of a key switch is provided to activate/inactivate the apparatus by means of a key 18.

Electrical conductors or cables 20, 22, 24, and 26 connect the control apparatus 14 respectively to the battery plus and minus terminals, the vehicle headlamps and the ignition coil of the vehicle.

Cable 28 interconnects sensing apparatus 12 and control apparatus 14, the former being located within the vehicle passenger compartment and the latter in the engine compartment.

In Fig. 3, the electrical output connections numbered 6, 7 and 8 of the control unit are jointly identified by reference numeral 28 as being connected by that cable to the sensing unit 12. Likewise, the output connections, numbered 3 and 4, to the key switch are jointly indicated by reference numeral 30 and there is an external connection through connectors numbered 1,2 for an external siren through a cable 32. The internal siren connections are indicated by numeral 34.

In Fig. 3 the connections 20, 22, 24 and 26 to the vehicle battery, headlamps and coil are identified by the same reference numerals as in Fig. 1.

In Fig. 2, output connections identified in parentheses by numeral 6, 7 and 8 are indicated jointly by the numeral 28 of the connecting cable between the sensing unit and the control unit.

Ultrasonic transmitter 38 driven by exciter circuit 39 emits an ultrasonic wave which circulates within the vehicle and is received by receiver 40 which detects and processes the signal by means of circuit 42, the output signal generated by the sensing apparatus being applied to output connection (7) and thence transmitted to the control apparatus 14.

The circuit shown in Fig. 3 of the control apparatus includes the function that the connections numbered 6, 7 and 8 are sensitive, after activation of the circuit, to any discontinuity in the connection via cable 28 to the sensing unit, such as would result from tampering with the system or wire cutting by an intruder.

The detector circuit can be considered as several individual elements namely.

1). Xtal oscillator and transmitter drive cct.

2). Reciever and H.F. amplifier stage.

3). Phase change demodulator.

4). Tailored L.F. amplifier.

5). Output buffer.

6). Flashing LED and zenner limiter.

The X-tal runs at a frequency of 32768Hz, and drives, via a pair of inverter stages, the Tx transducer at twice supply rail voltage. The transducer is resonant at this frequency and propogates a wave pattern which is sinusoidal at a viewing angle of 40 .

Reflected waves are detected by the Rx transducer and amplified by the H.F. amplifier, having a gain in excess of 51dB. The TL072 amplifier is of the low noise type with high input impedence and bandwidth.

The demodulator section, unique because the familiar analogue switch is replaced by a diode bridge, supplies the L.F. amplifier with the 'beat' frequency. It samples the H.F. amplifier output 32768 times each second. The demodulators output is integrated, removing any H.F. components. L.F. components are unfiltered by the integrator.

The L.F. amplifier is tailored to respond to any movement within the range 18cm sq. to 1.8m sq. Maximum gain between this range exceeds 30dB.

The L.F. amplifier output is diferentiated and buffered with an inverter. Drift of the amplifier output will not cause an alarm signal. The detector output is active low (alarm state).

A flashing LED is provided to indicate 'ON' status and behaves as a deterent. A zenner diode limits the voltage applied to this indicator.

No sensitivity control is provided. Any movement of > 18 cm sq. and < 1.8 sq.

within a 7m range from the detector will generate an alarm condition.

Fig. 4 shows a modification of the sensing apparatus of Fig. 2.

X1, IC2a and associated components form a free running oscillator, running at a frequency of 32.768 KHz. IC2b and c form a buffer/inverter stage to drive the transmitter (Tx) at twice supply rail.

Reflected signals are received by Rx and amplified by amplifier ICla, which has a maximum gain in excess of 53dB. RV1 is used to set the desired sensitivity.

D1-D4 form a phase detector which is continually comparing transmitted and received signals. Any movement within the surveillance area will shift the phase and this At component appears at the input of IClb. C2 and R4 form a simple integrator to elliminate high frequency components at 1Clb input.

R5, R6, C3 and C4 tailor the response of IClb, allowing intruder movement between 18 cm/s and 1.8 m/s to be detected.

IC2d and e generate two complementary 15tus wide pulses which drive the analogue switch phase detector. The output from ICla is sampled during this period and occurs 32768 times each second.

Differentiator C5 and R7 pass positive going edges at iClb output to buffer IC2f. The output from this gate is sensed by the interface unit and is active low (high in non-alarm state).

R11, C8, C9 and C10 and C11 provide decoupling to the entire circuit while C1, R2 and R3 provide a stable reference for ICla.

D6 is a flushing Red LED, current being limited by zenner diode D5.

D8 is a photo diode and conducts when it detects I.R. pulses from the Ultrascan transmitter. D8 is omitted on keyswitch operated version.

Attention is directed to the use of bridge rectifier D1-D4 as an analogous switch for demodulating the signal. This feature of the circuit has benefits in relation to lowering the component count of the apparatus.

Fig. 5 shows a modification of the control apparatus of Fig. 3.

With the keyswitch in the 'off' position, terminals 5 and 6 of the terminal blocks are held at the same potential, causing T1 to be held off. When the keyswitch is on (open circuit), T1 is held on via R4 and the circuit is powered up.

Alarm signals (active low) from the detector unit trigger IC1 via terminal 2. The output (IC1 pin 3) goes high for a duration of 2 minutes (or longer if intruder persists). Switch S1 selects delayed or instant operation by switching R8 out or in circuit respectively.

Transistor T2 drives the internal siren (and any other external devices) via lC2b, IC2c and R1 1. Relay RL1 is energised at the same instant and interupts current to the vehicles ignition coil via green connections.

IC2d is enabled to oscillate via D3, and R12 during the alarm on period, driving T3 on and off at a frequency of =0.5c/s. T3 turns T4 and T5 on and off at the same rate to flash left and right hand indicators via yellow connections.

An exit delay of 25 seconds is generated via IC2a, C3 and R10. lC1 is reset during this period and cannot be triggered via the detector or door switches. Door switches are connected to terminal 4, if required, and activates the system via D1.

With remote systems, direction indicators can be activated via terminal 9 (active low) to differentiate between armjng and disarming the system.

Decoupiing is achieved via R5, C5 and C6.

Attention is particularly directed to the tamper-proofing features of this circuit based around T1. The key switch connected to connectors 5 and 6 is protected against tampering by virtue of earth leakage via R4 due to the 12 volt positive potential on connector 8.

Likewise, the connections numbered 1 and 2 and 3 to the detector unit are also tamperproofed by virtue of R6 effectively grounding pin number 2 of IC1 whereby tampering with these connections leads to generation of an alarm response.

The key switch may be mounted in an exterior position on the vehicle. In this latter case, the switch itself may be provided with weather-proof cap which serves to inhibit the ingress of moisture which otherwise tends to cause malfunctions and a reduction in service life.

In Fig. 5 the connections of the control apparatus are analogous to those of Fig. 3, the numbering of the connections to the siren, key switch and detector unit being in fact reversed with respect to Fig. 3.

Figs. 6 and 7 show receiver or decoder apparatus of an infra-red remote control system for the apparatus of Figs. 1 to 5.

Terminal 8 is the positive supply to the decoder: REG1 generates the 5v supply for the remaining circuitry.

Pulses received by the photo-diode (within the detector) enter the decoder via terminal 4.

Due to the effect of ambient light, small currents flow through the photo-diode: this is rejected by the 'active load' circuit consisting of T3, R3, R4 and C3. Any fast transitions occuring (due to valid l.R. pulses being received by the photo-diode) are sensed by ICla, connected as a reference comparator.

Positive transitions at ICla output clock IC2, a 10 bit Johnson counter, which generates a high at Q8 after 8 pulses have been received.

This prevents further counting of input pulses via CKE input and enables PCB2 via the encode data line. The eight pulses represents the identification code being Ofof. R8, C7 and lClb cause a reset to be generated when the decoder is first powered up and 2 seconds after the first pulse has been received.

PCB2 analyses the data frame once encode data has gone high. If two successive valid data frames have been received, the VAL line is sent high.

IC3, a D-type, switches state on reception to a 'VAL' pulse from PCB2. Either state change causes iC4a output to go high for -1s due to timing components C9/R12 or C10/R13. This high enables, for the same duration, gates IC4b and c. A 'lock' output occurs on terminal 3 (active low) when the system is being armed. Conversely, an 'unlock' output occurs on terminal 2 (again, active low) when the system is being disarmed.

Terminal 6 provides an interface to drive the indicators via the interface unit. One single flash indicates the system is being armed.

Three flashes indicates the system is being disarmed.

Transistor T1 provides drive to the interface unit, turning the system on and off, depending on the output state of IC3.

IClb and associated circuitry form the system clock, running at 560KHz (in sympathy with the transmitter). IC2, a high speed 12 bit counter is prevented from counting until the 'Encode data' line goes low-this occurs after 8 pulses have been received by PCB1-IC2 (PCB2 is then taken out of RESET state). Syncronisation has now occured, and IC4 is sequentially scanned to compare incomeing data with its own program.

Output D3 from the EPROM (IC4) generates the 'window' periods, which coincide with pulses entering IC3b (assuming a valid code).

If an incoming pulse exsists without a 'window' being generated, the error latch (IC3a) is set. This situation also occurs if a 'window' is generated, there being no incoming pulse.

The error latch is interrogated, after two date frames have been received, via R5 and C6. If the error latch is still in clear state, a valid signal is sent to PCB1 via ICla. This occurs after two repetative data fames have been received.

Attention is particularly directed to the coding facilities of the above apparatus, namely the EPROM derived pulse position modulated code. As a result, in this embodiment more than 35,000 permutations of the code can be provided without repetition and considerable user security is provided against actuation by possessors of other infra-red control systems.

Fig. 8 shows remote control transmitter apparatus for controlling the apparatus of Figs.

6 and 7.

Push button S1 applies power to all three l.C's: C5 remains charged at all times via R5.

Whilst powered up, X1 runs at a frequency of 560KHz, supported by R1, C1 and C2.

lC2, a high speed 12-bit binary counter, generates the address scan for lC3, a low power 2K EPROM. Once the first 1K of EP ROM has been addressed, IC2 Q11 goes high which latches IC3 A8 high. The second 1K of EPROM is now continuously scanned, giving rise to repeated data frames. R2 and C3 ensure the latch (IC1) is reset on power up, setting IC3 A8 low at first. Therefore, only a single identification frame is sent, followed by repeated data. The first block of the identification frame is always zero, allowing the resonator (X1) to start up and settle at its correct frequency.

One bit (Q3) of the EPROM is used to pulse the Infra red LED via buffer (inc1) and a current magnification circuit consisting of R5, R6, C5 and FET1. When a pulse is to be generated, 03 goes low for=4s (two EPROM locations) and turns on FET1 for the same duration. C5 is partially discharged as a current of 2 amps (limited by R6) passes through D1, C5 is allowed to fully charge via R5 once Q3 returns high.

C4 provides the necessary decoupling and R4 ensures C3 and C4 fully discharge once S1 is released.

Attention is directed to the features of the above infra-red control system whereby it is capable of remotely disarming the alarm system and providing pre-arranged signals, executed for example by the indicator or light systems of the vehicle, confirming disarming or arming of the vehicle, and/or locking of same. In this way, on leaving the vehicle, it can be locked and windows closed and aerial retracted together with arming of the alarm system. Corresponding disarming and unlocking being likewise provided. In both situations an appropriate visual response from a lighting system of the vehicle can provide confirmation of properly coded instructions.

Claims (9)

1. Vehicle protection apparatus comprising sensing means to sense an unauthorised action with respect to the vehicle, and control means to activate/inactivate the apparatus as required, the apparatus being arranged to actuate protection response means upon detection of an unauthorised action in relation to the vehicle, characterised in that the sensing means comprises ultrasonic signal transmission and reception means located, in use, in a first part of the vehicle such as the passenger or driver compartment or the goods compartment, the sensing means being responsive to changes caused by actions of an intruder such as opening a door or window or effecting a blow thereon, the apparatus further comprising control apparatus connected by electrical conductors to said sensing means and responsive to a signal therefrom to actuate said protection response means, said control apparatus comprising means to actuate said protection response means upon the occurrence of any electrical discontinuity in the electrical conducts connecting the control apparatus to the sensing means.

2. Apparatus according to claim 1 wherein the control apparatus is located, in use, in a second part of the vehicle separate from said sensing means, for example in the engine compartment of the vehicle.

3. Apparatus according to claim 1 or claim 2 wherein said control means is adapted to be located inside a vehicle and is provided with time delay means whereby after activation of the apparatus a time delay occurs before it becomes responsive to signals sensed, whereby the user may leave and close the vehicle.

4. Apparatus according to any one of the preceding claims wherein said control apparatus is arranged to actuate said protection response means upon the occurrence of any electrical discontinuity in the electrical connection to said manual control means, or other tampering therewith.

5. Apparatus according to any one of the preceding claims wherein said control apparatus comprises a bridge rectifier acting as demodulator of signals received from said sensing means.

6. Apparatus according to any one of the preceding claims wherein said manual control means comprises switch means adapted to be mounted in an exterior location on a vehicle and having an openable cap to inhibit the ingress of moisture.

7. Apparatus according to any one of the preceding claims in combination with infra-red remote control means therefor, said infra-red control means being adapted to transmit an EPROM derived coded signal.

8. Vehicle protection apparatus substantially as described herein with reference to the accompanying drawings.

9. Vehicle protection apparatus characterised by sensing means comprising ultrasonic signal transmission and reception means.