Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2001-05-25
2003-11-18
Lee, Benjamin C. (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S425500, C340S539100, C340S902000
Reexamination Certificate
active
06650242
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to movement detection systems and particularly to movement detection systems in combination with warning devices that are activated by the movement detection systems. More particularly, the present invention relates to improvements in systems for detecting the proximity of movement within a hazard zone or area, particularly the movement of mobile plant and other moving vehicles or of the movement of people approaching a hazard, and then warning people of the presence of such vehicles in close proximity to them or of them approaching the hazards when detected by the detection systems in order to reduce the risk of accidents which could result in injury or death or damage. Even more particularly, the present invention relates to a fork-lift truck alert system to warn people in close proximity to the fork-lift of its presence so that people are aware that the fork-lift is close by so that they can take evasive action or remain out of harm's way until the fork-lift moves away or departs the hazard zone. Also, the present invention relates to a portable hazard warning system that alerts people that they are approaching a hazardous area or zone.
The present invention finds particular application as a safety system comprising the proximity detection system and warning system for use in a work place, such as for example, a factory, warehouse, transportation facility, such as an airport, or the like to alert workers to the proximity of a hazard.
Although the present invention will be described with particular reference to one form of the detection system and warning system activated by operation of the detection system for alerting people to the presence of a fork-lift truck or similar in a work environment, it is to be noted that the scope of the present invention is not limited to the described embodiment, but rather the present invention is more extensive in scope by including other forms and arrangements of both the movement detection system and the warning system and the uses of the forms of both systems in other applications including both fixed and portable systems.
Mobile plant, including fork-lift trucks, pallet carriers, road transport vehicles, tractors, cranes, excavators, vehicles generally and the like often present a significant injury hazard to personnel in the work environment such as for example in factories, warehouses, transportation facilities or the like, when these vehicles are operating in areas where pedestrians may also be present, particularly in confined areas where pedestrians and vehicles share a common path, roadway or similar. As the vehicles are often large and heavy, even when travelling at a slow speed, any pedestrian collision accidents are generally serious or fatal to the pedestrian, and often result in damage to surrounding structures. There have been some other systems in use for detecting and warning of the presence of mobile plant and vehicles. For example, one previously available technique employed one or more fixed linear infra-red beam detector or detectors which trigger an alarm when the linear beam impinging on the detector is broken or otherwise interrupted by passage of a vehicle across the beam which temporarily disrupts the beam allowing the alarm to be activated. Another previously available example is the use of a visible flashing hazard warning light mounted on the vehicle or mobile plant, particularly at or towards the top of the vehicle where it could be seen more readily, and the use of the vehicle's horn or reversing beeper to warn pedestrians of the proximity of the vehicle to the pedestrian in high risk areas, such as for example, in shared carriageways or similar. A further previously considered proposal is the use of radio frequency devices, such as for example, vehicle mounted transponders and associated fixed detection devices or readers to detect the presence of the vehicle or plant which activates a warning device such as either a visible or audible warning alarm.
However, all of these previously available methods and devices have not been entirely successful for a variety of reasons since they suffer from one or more various disadvantages and shortcomings. In the example in which a fixed linear infra-red beam sensor is used to generate a pedestrian warning alarm, the main disadvantages are that the alarm can be triggered by movement of pedestrians through the beam as well as by passage of vehicles through the beam, which produces many “false-alarms” or “false-triggerings” of the warning device which has a tendency to cause complacency in pedestrians and other nearby workers. Further, the coverage of an extended detection area providing reliable and sufficiently early warning in all instances is difficult, as well as expensive, to install and to maintain due to the linear nature of the beams of radiation.
The use of a flashing hazard lamp, horn, reversing beeper or similar devices fulfil a basic safety role, but have the disadvantages that the hazard lamp or other visible warning device may not be visible to a pedestrian at an obscured location, such as at a doorway, in a corridor or at a corner where the vehicle is unsighted by the person until it is almost too late to avoid a collision. This is particularly so when the vehicle and pedestrian simultaneously approach the same closed swinging door from either side. Further, ambient site noise may mask the audible horn warning because the horn may be sounded on the other side of a doorway or closed door or the operator may forget to operate the horn at all of the high hazard locations so that the pedestrian is unaware of the approaching vehicle. Radio frequency transponder-based systems have the typical disadvantages of high directionality, and/or of restricted range which is typically of up to a few meters only which does not provide sufficient coverage of the work area and which is often insufficient to provide adequate warning for the person, respectively. There is also the difficulty in defining and/or restricting the zone of coverage using these types of systems which in turn restricts their usefulness in such applications. As the radio frequency transponder-based systems are essentially linear it is difficult to comprehensibly cover a designated area of the workplace unless a complex array of components are used. Accordingly, there has not, at the time of developing the present invention, been any significant application of radio frequency-based technology to fork-lift or mobile plant safety warning systems, or to portable hazard warning systems despite radio-based technologies being available for many years.
Non-transponder based radio frequency systems have also been tried, however these typically suffer from difficulties in defining a stable triggering distance leading to false alarms being triggered and also difficulties in containing the triggering signal such that it does not trigger detectors in other zones by passing through walls.
Therefore, it is an aim of the present invention to provide a detection system for detecting the presence of a mobile plant, such as a fork-lift truck, in the vicinity of the detection system which activates a warning system to alert people in close proximity of the presence of the vehicle in response to detection of the presence of the vehicle in order to reduce or eliminate the risk or injury or damage caused by collision with the vehicle. It is also an aim of the present invention to provide a portable hazard detection and warning system for personal use.
BRIEF SUMMARY OF THE INVENTION
According to the present invention there is provided a movement detection and warning system comprising a transmitter means for transmitting a signal in association with an event or an object, the signal being adapted for triggering a detector means, said detector means being tuned to only detect the signal transmitted by the transmitter means when the detector is located within a predetermined distance from the transmitter means, said detector means activating an alar
Clerk Frederick George
Mahdavian Hossien
Embridge Lake Pty Ltd
Killworth, Gottman Hagan & Schaeff LLP
Lee Benjamin C.
Nguyen Phung
LandOfFree
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