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Title:
EMERGENCY SAFETY SWITCH AND SYSTEM
Document Type and Number:
WIPO Patent Application WO/2004/048844
Kind Code:
A1
Abstract:
An emergency safety switch system for moving machinery or vehicles has activation means carried or worn by an operator, whether in a control room or having alighted from a vehicle, etc. The activation means communicates (eg via a radio link) with control means on the machinery or vehicle that can override its normal operation. In the event of an emergency, the operator presses a button or voices a command or shout to activate the system. The system stops the machinery or vehicle, sounds an alarm, and may partially reverse its operation. Senses may be provided to determine if an operator has entered a higher risk area, in which case only a lower level of activation is required to deactivate the vehicle, etc.

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Inventors:
HARRIS BERNARD JAMES (AU)
Application Number:
PCT/AU2003/001577
Publication Date:
June 10, 2004
Filing Date:
November 25, 2003
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
HARRIS BERNARD JAMES (AU)
International Classes:
A01D75/20; B60K28/00; F16P3/14; (IPC1-7): F16P3/00; B60K28/14; A01D75/20
Foreign References:
DE10026263A12001-03-08
GB2198614A1988-06-15
FR2745418A11997-08-29
Other References:
PATENT ABSTRACTS OF JAPAN
Attorney, Agent or Firm:
Earley, Martin (PO Box 453 Collins Street West Melbourne, VIC 3007, AU)
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Claims:
CLAIMS
1. An emergency safety switch system for use by an operator of moving, rotating or reciprocating machinery or vehicles the safety switch system including: an activation means having an emergency activation mechanism that is attachable to the operator and readily activated by the operator in the case of emergency; an emergency control means in operative connection with the moving, rotating or reciprocating machinery or vehicle being controlled by the operator and which can override the normal operation to instigate an emergency control action; a communication means for communicating between the activation means and the emergency control means; wherein in the case of an emergency the operator at any position in or around the moving, rotating or reciprocating machinery or vehicle being operated, the operator can issue an emergency signal by activating the emergency activation mechanism attachable to the operator and the emergency signal is received by the emergency control means to instigate the emergency control action.
2. An emergency safety switch for use by an operator of moving, rotating or reciprocating machinery or vehicles including: an activation means having an emergency activation mechanism that is attachable to the operator and readily activated by the operator in the case of emergency; and a communication means for transmitting an activated emergency signal from the activation means to an emergency control means which can be in operative connection with the moving, rotating or reciprocating machinery or vehicle being controlled by the operator and which can override the normal operation to instigate an emergency control action; wherein in the case of an emergency the operator at any position in or around the moving, rotating or reciprocating machinery or vehicle being operated, the operator can issue an emergency signal by activating the emergency activation mechanism attachable to the operator and the emergency signal is received by the emergency control means to instigate the emergency control action.
3. An emergency safety switch system according to claim 1 or 2 wherein the activation is a portable unit able to be with the operator at all times whether in a control room or alighting the vehicle or checking part of the machinery or vehicle.
4. An emergency safety switch system according to any one of the preceding claims wherein the activation means having an emergency activation mechanism is a voice activated means that is attachable to the operator.
5. An emergency safety switch system according to claim 4 wherein the loudness of the voice is the instructing signal received by the activation means such that a shout or scream above a certain decibel rating will be identified and acted upon.
6. An emergency safety switch system according to claim 4 wherein the activation means receives and acts upon a word structure that is not usually used so as to avoid accidental activation of the emergency means.
7. An emergency safety switch system according to any one of the preceding claims wherein the activation means operates on various audio cues and includes voice interpretation software for interpretation of the audio cues.
8. An emergency safety switch system according to any one of the preceding claims wherein the activation means is mountable on the operator in a position close to the mouth to allow ready receipt of emergency voice activating initiation.
9. An emergency safety switch system according to claim 8 wherein the activation means is an extension of a head mounted structure.
10. An emergency safety switch system according to claim 8 wherein the activation means is a unit mounted on the front of the operator's top torso clothing such as on a collar or between opposing collars.
11. An emergency safety switch system according to claim 8 wherein the activation means is a necklace type structure but having a length which does not dangle as such would cause injuries if close to machinery.
12. An emergency safety switch system according to claim 1 or 2 wherein activation means includes a physical means located on the operator for initiating activation.
13. An emergency safety switch system according to claim 8 wherein the activation means includes a button system on the wrist of the operator or a belt or otherwise located on the operator.
14. An emergency safety switch system according to claim 12 or 13 wherein the activation is a portable unit able to be with the operator at all times whether in a control room or alighting the vehicle or checking part of the machinery or vehicle.
15. An emergency safety switch system on a tractor allowing movability of the driver away from the driver location while the tractor is still operative, the safety switch system including: the tractor having a drive control and an emergency control means in operative connection with the drive control and which can override the normal operation of the drive control when an emergency activation occurs; a portable activation means having an emergency activation mechanism that is attachable to or carried by the operator and readily activated hands free by the operator for providing the emergency activation in the case of emergency; a communication means for communicating between the activation means and the emergency control means; wherein in the case of an emergency the operator at any position in or around the tractor being operated, the operator can issue an emergency signal by activating the emergency activation mechanism attachable to the operator and the emergency signal is received by the emergency control means to instigate the emergency control action.
16. An emergency safety switch system according to any one of the preceding claims wherein the activation means includes a higher risk input assessor, with the assessor receiving signal from one or more sensors to determine that the operator is entering a higher risk area such as leaving the control cabin and the activation means having more than one level of activation whereby in a normal operation a first level of activation is required however when assessor has determined operator is in a higher risk area a lower level of activation is required.
17. An emergency safety switch system according to claim 16 wherein the first level of activation could be that a double signal such as when in the cabin two instructing words for a voice activation system or two depressions of the button if a mechanical switch activation system, however when determined to be in a higher risk area only a single word or single depression of the button is required for activation, wherein by receipt of a first signal from a locator sensor and upon the receipt of a second signal from the activation means worn by the operator who is now away from the normal controls will immediately instigate emergency action.
18. An emergency safety switch system according to any one of the preceding claims wherein the emergency control action results in stopping the progress of the machine or vehicle or a.
19. An emergency safety switch system according to any one of the preceding claims wherein the emergency control action results in stopping the progress of the machine or vehicle and partially reversing the normal action of any connected cutting mechanisms or reciprocating mechanisms the emergency control action stops the machine to prevent the cutting of a limb of the operator accidentally in the mechanism while further partially reversing the normal operation so the operator releases the limb from the machinery.
20. An emergency safety switch system according to any one of the preceding claims wherein the emergency control action also instigates an alarm signal to be sent to a siren for communicating audibly the emergency condition.
21. An emergency safety switch system according to any one of the preceding claims wherein the emergency control action results in an alarm signal being transmitted by radio transmission or otherwise to a control base for instigating follow up emergency actions.
22. An emergency safety switch system substantially as hereinbefore described with reference to the drawings.
Description:
EMERGENCY SAFETY SWITCH AND SYSTEM BACKGROUND ART This invention relates to an emergency safety switch and system for use by operators of moving, rotating or reciprocating machinery or vehicles. It is particularly related to an emergency safety switch and system for use by operators of tractors in farms and the like where the operator is often acting alone in a large area.

It is known to have voice operated control of vehicles or safety devices dependent on condition of vehicle or person. In US Patent No. 5,931, 254 there is disclosed a non- contact operator presence sensor in which a power machine includes a frame and a plurality of power actuators operable coupled to the frame. A power circuit is coupled to the power actuators and provides power to the power actuators. A cab is operably coupled to the frame and defines an operator compartment. The cab includes a seat supported in the operator compartment. A non-contact operator presence sensor is coupled proximate the cab and is configured to sense presence of an occupant in a predefined volume proximate the seat. The operator presence sensor provides a sensor output signal indicative of operator presence. A controller is coupled to the operator presence sensor and is configured to control operation of at least one of the plurality of power actuators based on the sensor output signal. This has the problem that the system clearly senses if the operator is present. Therefore there is an automatic override of the operator in that control cannot occur if not detected. The operator has no input or override capabilities and therefore such is not of use for emergency situations.

In US Patent No. 4,543, 957 there is disclosed a human response apparatus and method. Responses of a human subject may be by voice, hand or foot movement, or bodily secretions, as examples. A hiatus of such responses may be termed a lapse in the continuity of the response, including a hesitation pause in the voice, a movement of hand or foot on a monitored control of a motor vehicle or vehicle simulator, or pulsatile bodily secretions on a monitored control of an implantable insulin pump. In a

voice response, the hesitation pause may be more than about one second in the voice of a subject during a dialogue or monologue. The hiatus rate of such responses is indicated by the present apparatus, as is the average hiatus duration for two or more hiatus rates. The dominant hiatus rate is also determined and indicated. A microprocessor is utilized in such determination. The problem with this system is that it requires predetermined features to be defined and approximated of the intended user so that automatic operation occurs when those estimated features are detected. In essence therefore the machine is stating if you require an action and not the operator.

Although such is required in man fields it does not fulfil the need of emergency action.

US Patent No 5,450, 525 discloses a vehicle accessory control with manual and voice response. A voice controlled vehicle accessory system is responsive to voice commands and/or manual commands, wherein the manual commands are entered via a single pushbutton having multiple functions depending upon the instantaneous state of a system controller. The present invention provides an accessory control, which avoids false activation of the system by the voice recognition unit while improving accessibility of the accessory to a user, by providing manual control. The problem with this system is that it is only related to accessories on the vehicle while the operator is driving the vehicle. It is therefore only controlling non-essential equipment such as radios, air conditioners or the like. It does not provide an emergency structure.

Also in US Patent No. 4,940, 964 there is a vehicle control and theft deterrent with remote transmitter. There is disclosed a motor vehicle control system having a vehicle control unit located in the motor vehicle and a hand held portable control unit, which are in two-way communication. The vehicle control unit which is located in the motor vehicle includes a receiving antenna, a receiver, a decoder and a plurality of functional control circuits, with each control circuit for a respective functional operation of the motor vehicle such as ignition, starter activation, heater, air conditioner, door locks, etc. The control unit in the motor vehicle also includes a transmitter and a scanner unit which has a like plurality of sensors for sensing the condition of the various functional operations such as the ignition, engine operation,

air conditioner status, heater status, etc. The control unit transmits a radio frequency signal to the remote control unit, which indicates the condition of the sensed operations. The remote control unit has an antenna and receiver with an audio amplifier and speaker. The remote unit has a standard keypad in circuit to an encoder to produce a signal that is applied to the transmitter for transmission to the vehicle control unit. In a preferred embodiment, the motor vehicle control unit has a voice synthesizer to generate a voice signal that is transmitted to the remote control unit, and most preferably has a digital voice recorder, permitting the user to customize the unit to repeat any selected message. This is particularly of value to adapt the system for foreign language users. This system provides security for the vehicle when locked and unattended but does not control operation in any emergency sense.

Clearly assessments of emergencies by sensors generally occur after an injury or malfunction or accident. Therefore it is too late to prevent the injury or malfunction or accident. An operator while testing, checking or undertaking other tasks might be able to foresee the imminent occurrence but no opportunity is provided in known systems to take any action unless the operator is at the normal controls.

Therefore although parts of systems are known it is not known to form a combination portable unit enabling the user to selectively operate an emergency action of vehicle as required and not as detected to assessed to be required.

It is therefore an object of the invention to provide an emergency safety system and apparatus, which overcomes or at least ameliorates the problems of the prior art.

SUMMARY OF THE INVENTION In accordance with the invention there is provided an emergency safety switch system for use by an operator of moving, rotating or reciprocating machinery or vehicles including: an activation means having an emergency activation mechanism that is attachable to the operator and readily activated by the operator in the case of emergency; an emergency control means in operative connection with the moving, rotating or reciprocating machinery or vehicle being controlled by the operator and which can override the normal operation to instigate an emergency control action; a

communication means for communicating between the activation means and the emergency control means; wherein in the case of an emergency the operator at any position in or around the moving, rotating or reciprocating machinery or vehicle being operated, the operator can issue an emergency signal by activating the emergency activation mechanism attachable to the operator and the emergency signal is received by the emergency control means to instigate the emergency control action.

Also in accordance with the invention there is provided an emergency safety switch for use by an operator of moving, rotating or reciprocating machinery or vehicles including: an activation means having an emergency activation mechanism that is attachable to the operator and readily activated by the operator in the case of emergency; and a communication means for transmitting an activated emergency signal from the activation means to an emergency control means which can be in operative connection with the moving, rotating or reciprocating machinery or vehicle being controlled by the operator and which can override the normal operation to instigate an emergency control action; wherein in the case of an emergency the operator at any position in or around the moving, rotating or reciprocating machinery or vehicle being operated, the operator can issue an emergency signal by activating the emergency activation mechanism attachable to the operator and the emergency signal is received by the emergency control means to instigate the emergency control action.

The invention also provides An emergency safety switch system on a tractor allowing movability of the driver away from the driver location while the tractor is still operative, the safety switch system including: the tractor having a drive control and an emergency control means in operative connection with the drive control and which can override the normal operation of the drive control when an emergency activation occurs; a portable activation means having an emergency activation mechanism that is attachable to or carried by the operator and readily activated hands free by the operator for providing the emergency activation in the case of emergency; a communication means for communicating between the activation means and the emergency control means; wherein in the case of an emergency the operator at any position in or around the tractor being operated, the operator can issue an emergency

signal by activating the emergency activation mechanism attachable to the operator and the emergency signal is received by the emergency control means to instigate the emergency control action.

It can be seen that the invention provides a portable unit able to be with the operator at all times whether in the control room or alighting the vehicle or checking part of the machinery or vehicle. The device allows the emergency operation by the operator regardless of whether the vehicle or machinery or operator has been sensed to be in an emergency situation.

The activation means having an emergency activation mechanism can be a voice activated means that is attachable to the operator. This can be readily activated by the operator in the case of emergency by discerning a particular instructing word such as "STOP"or"HELP". The loudness of the voice could be the instructing signal such that a shout or scream above a certain decibel rating will be identified and acted upon.

It is also possible to incorporate a word structure that is not usually used so as to avoid accidental activation of the emergency means. In this way the words"STOP NOW" have a distinctive sound and distinctive rising of the voice and on the first word and lowering on the second. Various audio cues could therefore be used and interpreted through voice interpretation software.

Another means of activation is by a physical means located on the operator. In one form there can be a button system on the wrist of the operator or a belt or otherwise located on the operator. In the case of loud working environments the operator can readily instigate the emergency action by activating the button.

However for the voice form the activation means is mountable on the operator in a position close to the mouth. This can be an extension of a head mounted structure. In another form the activation means is a unit mounted on the front of the operator's top torso clothing such as on a collar or between opposing collars. Another form has a necklace type structure but having a length which does not dangle as such would cause injuries if close to machinery.

It can be seen that an important aspect is the location of the activation means on the operator. This is different to the usual operating means of the moving, rotating or reciprocating machinery or vehicle being operated where the controls will be in the control cabin or otherwise on the machinery or vehicle. In many circumstances the operator needs to move away from the machinery or vehicle and if something unexpected occurs, such as the operator falling over, there is no immediate access to the normal controls. Also it is often possible the moving, rotating or reciprocating machinery or vehicle malfunctions or enters a dangerous mode. This action itself might throw the operator away from the controls.

In the case of farm tractors where the operator often alights from the tractor to check the attached machinery or the resulting processing there is often a higher than usual likelihood of the operator falling over. There is also a high likelihood that tractors when traversing non flat terrain topple over and the operator is thrown out of the cabin or pinned under the tractor. Urgent action to prevent further injury is required.

The activation means can further include a higher risk input assessor. The assessor could determine that the operator is entering a higher risk area such as leaving the control cabin and thereby lessen the requirements for activation. This could be that a double signal is required when in the cabin such as two instructing words if it is a voice activation system or two depressions of the button if a mechanical switch activation system. In this way the accidental depression of the button or accidental use of the instructing word in the control cabin will not accidentally activate the emergency action. Instead a first signal is received from a locator sensor and upon the receipt of a second signal from the activation means worn by the operator who is now away from the normal controls will immediately instigate emergency action.

The emergency control means, which is in operative connection with the moving, rotating or reciprocating machinery or vehicle being controlled by the operator, can be a secondary switch in the normal controls to switch off the machine or vehicle.

Alternatively it could merely be a secondary input to the normal controls. However the receipt of the emergency signal must override the normal operation to instigate an emergency control action. Apart from the action of turning off the machinery or

vehicle the control action could include other actions or be a distinctly different operating action.

In one form the emergency control action could be to stop the progress of the machine or vehicle and to partially reverse the normal action. In this way if a vehicle such as a tractor with following harvesting mechanism has rolled onto the operator the emergency control action can be to stop the progress of the tractor so that the harvesting mechanism does not shred the operator while also performing a partial reversal of direction so that the tractor reverses off the operator. In cutting mechanisms or reciprocating mechanisms the emergency control action can be to stop the machine to prevent the cutting of a limb of the operator accidentally in the mechanism while further partially reversing the normal operation so the operator can remove the limb from the machinery.

The emergency control action can also instigate an alarm signal to be sent to a siren for communicating audibly the emergency condition. The alarm signal could instead of or as well be transmitted by radio transmission or otherwise to a control base for instigating follow up emergency actions.

The communication means for communicating between the activation means and the emergency control means can be a radio communication means with a transmitter incorporated in or associated with the activation means and a receiver means incorporated in or associated with the emergency control means. Other types of transmission apart from radio waves can be used particularly if the operating conditions include other radio signals that might cause interference.

Therefore in the case of an emergency the operator at any position in or around the moving, rotating or reciprocating machinery or vehicle being operated, the operator can issue an emergency signal by activating the emergency activation mechanism attachable to the operator and the emergency signal is received by the emergency control means to instigate the emergency control action.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the invention might be more readily understood an embodiment will be described by way of illustration only with reference to the drawings wherein: Figure 1 is a diagrammatic view of an emergency safety switch and system in accordance with a first embodiment of the invention with the safety switch being mounted on the chest of the user such as by necklace; Figure 2 is a schematic view of the transmitter of the emergency safety switch and system of Figure 1; and Figure 3 is a schematic view of the receiver of the emergency safety switch and system of Figure 1; and Figure 4 is a diagrammatic view of an emergency safety switch and system for a tractor in accordance with a second embodiment of the invention with the safety switch being mounted on the head of the user such as by ear muffs.

PREFERRED EMBODIMENT OF THE INVENTION Referring to the drawings there is shown an emergency safety switch system for use by an operator of moving, rotating or reciprocating machinery or vehicles. The system includes an activation means, an emergency control means and a communication means linking the two.

The activation means has an emergency activation mechanism that is attachable to the operator and readily activated by the operator in the case of emergency. The emergency control means is in operative connection with the moving, rotating or reciprocating machinery or vehicle being controlled by the operator and which can override the normal operation to instigate an emergency control action. The communication means for communicating between the activation means and the emergency control means. In the case of an emergency the operator, at any position in or around the moving, rotating or reciprocating machinery or vehicle being operated, can issue an emergency signal by activating the emergency activation mechanism attachable to the operator and the emergency signal is received by the emergency control means to instigate the emergency control action.

The emergency safety switch comprises an electronic device which allows the operator of moving, rotating or reciprocating machinery to immediately stop the machine by in one form the pressing of a button or in another form giving a loud audible command provided that the operator is within a required radius such as within 20 metres from the controls.

In the form shown in figure 1 the activation means is a necklace type structure but having a length which does not dangle as such would cause injuries if close to machinery. This form could be operative by pressing of a button or voice command.

In the form shown in figure 4 the activation means is a heads mounted structure such as integral with ear muffs that are required to be worn by operators of tractors or the like as a matter of health and safety. In this way the activation means is always with the operator. This form of activation means uses voice command and also has the benefit of maintaining a set distance from the operator's mouth to enable ready calibration of the voice signal type and strength.

The emergency safety switch and system consists of two separate parts as follows: Part 1 A transmitter unit is mounted on the operator's body and consists of a microphone and an electronic circuit that senses the operator's audible command and activates a coded radio transmitter, this circuit also includes a filter which filters out most of the mechanical noises picked up by the microphone during normal operation of the machinery. A mechanical switch is included which, when pressed, also activates the coded radio transmitter. When activated the radio transmitter emits a series of coded signals over a period of time. The transmitter unit is powered by dry cells and housed in a weatherproof casing which can be hung around the neck, worn on the wrist or attached to glasses or ear muffs or any other mounting point.

Part 2 A receiver unit is mounted on the machine or implement being controlled and consists of a radio receiver and an electronic circuit which, when it receives the coded radio signal (Alarm condition), immediately acts to close an operating switch so as to

disable the machine or implement being controlled and sound a loud audible alarm designed to alert humans and set dogs barking. The electronic circuit incorporates a decoder circuit to reject all transmissions except those with the exact code thus reducing the incidence of false alarms from other transmissions on the same frequency.

When installed, the switch is wired into the electrical circuit of the machine or implement such that if a contact closure or opening occurs the engine is immediately stopped and remains stopped until the ignition key or start switch on the implement or machinery is switched to the OFF position.

The receiver unit is powered by the battery supply in the machine or implement or other power supply and connected such that power is supplied at all times to the receiver unit. In addition the unit is wired to provide a fail safe condition to occur if the power to the receiver unit is interrupted at any time.

A typical embodiment of the emergency safety switch and system as shown in the drawings is as follows: PART 1 TRANSMITTER UNIT Referring to Figure 1 Transmitter Schematic, a transmitter PRESS BUTTON SWITCH is located on the transmitter housing and enables the operator to initiate the transmitter as required by a single press of the button. This action changes the state of one of the inputs of an"OR"gate which is biased to the zero state by RESISTOR R1 and activates a STANDBY SWITCH circuit which immediately switches on power to the Vss bus activating all other circuitry contained in the TRANSMITTER section.

The purpose of the STANDBY SWITCH is to conserve battery power when the Transmitter is not transmitting.

The MICROPHONE is continuously operating and is powered via resistor R2, it converts the audio sound pressure incident on its diaphragm to an electrical signal which is fed into the PRE AMPLIFIER which amplifies the electrical signal to a

suitable level for further processing. The output from the PRE AMPLIFIER is fed to the BAND PASS FILTER which filters out most of the background noise from the signal and passes the voice band frequencies through to the STANDBY SWITCH which monitors the level of sign from the BAND PASS FILTER and, when it exceeds a predetermined level immediately switches on power to the Vss bus activating all other circuitry contained in the Transmitter section. The output from the BAND PASS FILTER is also fed to the POST AMPLIFIER which amplifies the filtered signal up to a level suitable for the DURATION AND LEVEL SENSING circuit.

The DURATION AND LEVEL SENSING circuit tests the signal for a minimum duration and minimum signal level and if both are exceeded provides a signal to change the state of the second input of the"OR"gate.

If either or both of the inputs to the"OR"gate are changed from the normal state then the"OR"gate sends a pulse to the MONOSTABLE causing it to trigger its output for a period of time and initiate the ENCODER circuit for the duration of the pulse.

The ENCODER CIRCUIT produces a continuously encoded output which can be preset to a variety of digital code sequences by altering the on or off states of the 5 WAY DIP SWITCH. The ENCODER CIRCUIT output is fed to the TRANSMITTER SWITCH which switches the R. F. TRANSMITTER on and off to produce a series of bursts of R. F. energy at the antenna outpoint point in strict accordance with the encoded signal. The antenna output point is connected to the ANTENNA which radiates the energy as an electromagnetic field.

The duration of the output pulse from the MONOSTABLE circuit enables the encoder to generate a suitable number of coded sequences to ensure that PART 2 the RECEIVER UNIT can be sure that it has received the correct code thus reducing the possibility of false alarms.

The Transmitter unit circuitry is powered by the BATTERY built into the unit. The following components are permanently connected to the battery to ensure that the pressing of the switch or the loud voice command always initiates a coded transmission:

The following components: PRESS BUTTON SWITCH,"OR"GATE, MICROPHONE, PRE AMPLIFIER, RI, R2, BAND PASS FILTER and the STANDBY SWITCH are designed to ensure the minimum current drain is placed on the battery to achieve maximum battery life. In addition an ON/OFF SWITCH could be included so that the Transmitter unit can be switched off when the machine is not in use.

The BATTERY O. K. INDICATOR is connected to the PRESS BUTTON SWITCH circuit so that the LED will be switched on when the PRESS BUTTON SWITCH is pressed. When the Battery voltage falls to a point approaching minimum voltage required to reliably operate the Transmitter then the LED will not light.

PART 2 RECEIVER UNIT Referring to Figure 2 of the receiver schematic, an ANTENNA is tuned for optimum reception of electromagnetic radiation at the frequency radiated by the Transmitter unit and is connected to the antenna input of the R. F. RECEIVER. The R. F.

RECEIVER is tuned to receive the same frequency as that radiated by the Transmitter unit and processes the ANTENNA signal to provide a pulsed logic level output which in turn is connected to the DECODER. The DECODER continually interprets the incoming signal and compares it with a code sequence as selected by the 5 WAY DIP SWITCH. When a matching code is detected the output of the DECODER changes the logic state of its output for the duration that the incoming code exactly matches is own code sequence, this output is connected the DELAY TIMER which interprets the change of logic state as a start signal and likewise interprets the output reverting to its original state as the stop signal. If the elapsed time between the start signal and the stop signal exceeds the DELAY TIMER duration then the timer outputs a signal to the LATCH via its SET input causing the latch output to change state permanently until a signal is detected on the RESET input.

The Terminal 3 is connected via external wiring to the ignition circuit switch of the implement to which the Receiver unit is installed such that when the ignition key is returned to its OFF position the voltage to terminal 3 is switched off and the BUFFER

circuit changes the state of its output such that the RESET input on the LATCH circuit is activated to cause the latch to reset to its original state.

The output from the LATCH is connected to a RELAY DRIVER circuit which switches power to the RELAY coil and causes it to activate and change the state of its output contacts which are connected to RELAY OUTPUT terminals 4,5 and 6.

The RELAY OUTPUT is connected via external wiring to the electrical circuit of the machine or implement such that the change of state of the relay causes the immediate stopping of drive, mechanical, hydraulic, pneumatic or otherwise in as safe a manner as possible.

The output of the LATCH is also connected to another DELAY TIMER and when this output changes state the DELAY TIMER as initiated, if the LATCH output sustains the initiation the DELAY TIMER times out and activates its output thus energising the SIREN unit which produces a very loud sound sequence designed to be heard over long distances and also to cause Dogs to bark in response.

The Receiver unit is powered form the electrical circuit of the machine or implement to which it has been installed and input power is fed to terminals 1 and 2 which in turn are connected to a SUPPRESSOR circuit designed to eliminate all forms of electrical interference from the power source.

The electrical supply is then connected to the REGULATOR which regulates the supply voltage to a level most suitable to reliably operate the complete circuitry of the Receiver unit via the POWER TO ALL CIRCUITS +/-connections at the output form the regulator.

The principal aim of the above circuits is to obtain reliable operation of the complete SAFETY DEVICE and at the same time reduce the incidence of false activation or nuisance tripping to a minimum.

This may mean the addition of further circuitry as the design of the prototype units and their field testing progresses to the Production Design level.

The Transmitter unit could also include a word interpreter circuit that would limit the audible initiation to a specific word or words or phrases.

Additional interlocks could also be included such that the Transmitter unit PRESS BUTTON must be pressed before the machine could be started thus enforcing a system check each time the unit is operated. This would ensure that the operator had a functional emergency safety switch and system at the time of starting the machine.

Although this invention has been described in its preferred forms with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and numerous changes in the details of construction and combination and arrangement of parts can be resorted to without departing from the spirit and scope of the invention.

It should be understood that the above is a description of the preferred embodiments of the invention but the disclosure of the invention is not limited to those embodiments. Clearly other variations that would be understood by people skilled in the art without any inventiveness are included within the scope of the invention as defined in the following claims.