Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2000-03-17
2001-12-11
Wu, Daniel J. (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S552000, C340S649000, C340S600000, C340S661000, C340S662000, C340S628000, 36
Reexamination Certificate
active
06329924
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to electromagnetic radiation monitors of the type which may be worn by persons who may be exposed to potentially harmful levels of electromagnetic energy. The invention has particular application to monitors for electric fields, specifically the
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w-frequency fields of the type which surround high-voltage conductors, such as power transmission and distribution lines.
Transmission lines route high-voltage (e.g., 2,000 volts and higher) electrical power from power plants to main regional stations and local substations. Distribution lines route high-voltage electrical power from substations to end users. Many such lines are above ground and exposed to the elements, requiring frequent inspection and/or repair or maintenance. Contact with such high-voltage power lines can be lethal for workers and, therefore, there have heretofore been provided various types of monitors or detectors to sense the proximity to dangerous high-voltage power lines to warn workers before they reach a dangerous proximity. One such type of detector senses the electrical field surrounding a high-voltage conductor, the strength and extent of such fields being proportional to the voltage level. Such detectors typically provide an audible and/or visible indication of the detected field to warn the user.
Prior detectors of the personal or wearable type are battery-powered and have on/off switches. One difficulty, particularly with detectors having audible alarm signals, is that when a worker has to work for an extended period of time in a sensed electric field, the continuous audible alarm can become annoying. Thus, workers will frequently turn off the detector, which can be dangerous. Also, a worker must remember to turn the device on each time he wears it, and failure to remember this is also dangerous.
SUMMARY OF THE INVENTION
It is a general object of the invention to provide an improved electric field detector of the wearable type, which avoids the disadvantages of prior detectors while affording additional structural and operating advantages.
An important feature of the invention is the provision of a wearable electric field detector which prevents dangerous user deactivation.
In connection with the foregoing feature, another feature of the invention is the provision of a detector of the type set forth with an audible alarm device which can be selectively muted by the user in a safe manner.
In connection with the foregoing feature, another feature of the invention is the provision of a detector of the type set forth with an automatically time-limited muting function.
Still another feature of the invention is the provision of a shielded carrying case for a detector of the type set forth, so that the detector need not have an on-off switch.
Certain ones of these and other features of the invention may be attained by providing a wearable electric field detector comprising: a housing adapted to be mounted on a user's person, a sensing circuit disposed in the housing and responsive to an electric field for generating a sense signal which varies in proportion to the strength of the sensed field; an alarm circuit coupled to the sensing circuit for producing an indication of the sensed field, the alarm circuit including an audio annunciator for producing an intermittent audible alarm signal with a repetition rate which varies in proportion to the sense signal; and a mute circuit selectively operable when the audio annunciator is active for deactivating the audio annunciator.
Other features of the invention may be attained by providing in combination: a wearable electric field detector, the detector including a housing adapted to be mounted on a user's person, a sensing circuit disposed in the housing and responsive to an electric field for generating a sense signal which varies in proportion to the strength of the sensed field, and an alarm circuit coupled to the sensing circuit for producing an indication of the sensed field; and a carrying case adapted to receive the housing and including shield material for shielding the sensing circuit from electric fields when the detector is disposed in the carrying case.
The invention consists of certain novel features and a combination of parts hereinafter fully described, illustrated in the accompanying drawings, and particularly pointed out in the appended claims, it being understood that various changes in the details may be made without departing from the spirit, or sacrificing any of the advantages of the present invention.
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AVO International Flyer for LA500 Series Alarms-1997.
HD Electric Company
Nguyen Tai T.
Shaw Seyfarth
Wu Daniel J.
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