Communications: electrical – Condition responsive indicating system – Specified indicator structure
Reexamination Certificate
1999-11-02
2001-03-27
Hofsass, Jeffery (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specified indicator structure
C340S567000, C340S679000, C340S573300, C340S539230, C340S540000, C340S870030
Reexamination Certificate
active
06208260
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to personnel warning apparatus used for alerting workers in the path of traveling loads suspended from cranes or on moving vehicles, such as forklifts, and more particularly to a method and apparatus for selectively and personally warning only those workers in the immediate vicinity of a traveling load, especially loads passing over the worker's head.
2. General Background
Safety is a prime concern in the construction, manufacturing, and warehousing industries, especially for individuals working in the immediate vicinity of cranes or vehicles which are constantly moving various loads, often over the heads of the workers. Cranes and traveling vehicles, such as forklifts, generally sound an audible warning indicating that the crane or vehicle is traveling loaded or unloaded regardless of direction. Therefore, workers in the vicinity know the crane is moving but tend to disregard the warning since it is not specifically applicable to them most of the time. The workers simply become desensitized to the audible warnings and/or flashing lights as a result of their constant use, especially when few, if any, workers are in danger at any given time.
Ideally, only those workers who are in danger as a result of a traveling load passing in the near vicinity or overhead should be warned, giving them sufficient time to either move out of the path or at least be aware of the load's presence.
The same situation exists for back-up warning devices used on vehicles and the like. When a warning can be heard for long periods of time or seen and heard from long distances when no immediate danger exists, a certain degree of desensitivity develops. It is therefore becoming more imperative that only those workers who are being placed in immediate physical danger be warned. Some attempts has been made to automatically sence the presence of a worker who may be in harms way, as disclosed by U.S. Pat. No. 4,937,795. This system warns the vehicle operator of the presence of the worker, thereby placing full responsibility on the vehicle operator for avoiding the worker.
It is an object of the present invention to provide a system that alerts the worker only if the worker is in immediate danger and with sufficient time for the worker to take evasive action, thereby placing some responsibility on the worker for his own safety.
SUMMARY OF THE INVENTION
The present invention is based on the need to alert only those workers who are in immediate danger, thus increasing alertness and reducing the chance of desensitization of the workers to unnecessary alarms. In cases where loads are being moved in the vicinity of the workers by a crane, a directional signal transmitter, such as ultrasonic and/or infra-red is attached in a pendulum manner at the tip of the crane boom, thereby allowing the transmitter to align itself with the crane cable and its load regardless of the elevation of the crane boom. The transmitter further incorporates ultrasonic sensor and receiver for sensing and computing the distance from the crane boom tip to the ground or deck surface. Sensor computations are then fed into microprocessor which automatically adjusts an infra-red beam emanating from the transmitter in a conical beam configuration that encompasses the typical load generally transported, thereby forming a diametrical alert zone or field in the form of a field around the load. Therefore, the alert zone or field is always larger than the size of the load. Workers in the area below the overhead crane are provided with signal receivers for attachment to their hard hats which react to the signal being transmitted in the alert zone or field around the load being transported. The personal receiver is a miniature battery operated device combined with a visual and audible signal device, such as a flashing LED, and an audio device, such as a chirper or beeper. In any case, the visual indicator is attached to the worker's hat within the worker's peripheral vision, so as not to be distracting.
It is acknowledged that the load may potentially block a portion of the signal being directed toward and around the load. However, if the signal is detectable in a zone or field several feet in advance of the load, sufficient notice will have been received to gain the attention of the worker prior to the load being directly overhead. The zone or field directly under the load may also be covered by one or more portable signal generators attached to the load, generally at opposite corners or at the load's extreme ends. The load transmitters also produce a conical alert zone or field below the load, thus reinforcing the boom alert zone or field and covering some of the blind spots under the load. The portable signal generators have the same frequency as the crane boom transmitter but have a much smaller range. Therefore, only those workers within the zone or field around the load are alerted to the presence of a moving load.
It is also recognized that this technology can also be adapted to moving vehicles or vehicles carrying loads. In such cases, preferably an infra-red directional transmitter is located above the vehicle and directed towards the rear and downwards, thus producing an elliptical conical pattern for a limited distance behind the vehicle to warn workers of the vehicle when moving backwards. A second transmitter is mounted above the load and directionally aimed downward to form an elliptical conical pattern for a limited distance in front of the vehicle, thus alerting workers within the path of the approaching load or vehicle. Workers on either side and a considerable distance away are not being constantly bombarded with noise and light which could potentially be ignored.
A further use of the technology is to provide a fixed transmitter in known hazardous areas. i.e. areas, with dangerous levels of hydrogen sulfide, benzene, radon, radioactive materials, high voltages, or dangerous or sensitive equipment. Therefore, a worker entering such areas receives a personal audible and visual alert warning, while those outside the danger area are not exposed to a constant warning.
REFERENCES:
patent: 5005001 (1991-04-01), Cordery
patent: 5315289 (1994-05-01), Fuller et al.
patent: 5353011 (1994-10-01), Wheeler et al.
patent: 5440291 (1995-08-01), Foster, Jr. et al.
patent: 5677676 (1997-10-01), Bell, Jr.
patent: 5727758 (1998-03-01), Penza et al.
patent: 5949333 (1999-09-01), Lehmann et al.
Berjaoui Samir
Sperry David
West Jill
Hofsass Jeffery
Montgomery Robert N.
Nguyen Hung
West Jill
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