Electric lamp and discharge devices: systems – With signal – indicator – or alarm
Patent
1989-11-24
1992-04-14
LaRoche, Eugene R.
Electric lamp and discharge devices: systems
With signal, indicator, or alarm
315134, 315 89, H01J 160
Patent
active
051051249
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a device for detecting the failure or disconnection of any of a plurality of electric lamps connected in series and has particular reference to such a device which is suitably used for detecting the failure of any of a large number of taxiway or guide lamps illuminating the runway of an airfield.
BACKGROUND ART
There are known certain devices designed to detect the failure in any one of guide lamps simply by the occurence of a breakage of the circuit to which such numerous lamps are connected in series. Such known devices have a drawback in that failure of one lamp results in extinction of all of the remaining lamps.
Improvements have been made in which a switch is provided, as illustrated in FIG. 6 of the accompanying drawings, to give a short circuit to the terminals of each of serially connected lamps so that failure of any one lamp does not affect all the other lamps. However, this circuit device has the disadvantage that it is difficult to know which of so many remotely located lamps has failed and therefore to monitor all the lamps centrally from one place.
With the foregoing difficulties of the prior art in view, the present invention seeks to provide a device for detecting lamp failure which is capable of performing accurate detection and remote central monitoring of a large number of electric lamps.
DISCLOSURE OF THE INVENTION
The above stated object of the invention is achieved by the provision of a lamp failure detecting device which essentially comprises a transformer for extracting power from a lamp power line, said transformer being operable in response to the existence of current flowing through a corresponding lamp, a signal generator operable by an output voltage of the transformer, and a means of superimposing an output signal from the signal generator onto the lamp power line as an induced current. The transformer comprises a core disposed on the lamp power line, the lamp power line is wound on the core as a first winding, and a second winding on the core for detecting the output of the first winding. The signal generator which may be structured to use a current extracted from the output voltage of the second winding, has an oscillator adapted to generate a frequency corresponding to a frequency specified for each of the serially connected lamps. An output signal having this frequency is fed back as an output current signal via a third winding and superimposed on the lamp power line. Thus, in the event of failure of any one lamp, this can be confirmed by detecting the existence of such feedback signal in that particular lamp circuit.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic circuit diagram illustrating a lamp failure detecting device according to one embodiment of the invention;
FIG. 2 is a schematic circuit diagram showing a plurality of lamps connected in series;
FIG. 3 schematically illustrates the terminals being short-circuited upon failure of a lamp filament;
FIG. 4 is a schematic circuit diagram illustrating a lamp failure detecting device according to another embodiment of the invention and associated with a central monitoring arrangement;
FIG. 5 shows a modified circuit in part of FIG. 4; and
FIG. 6 is a schematic circuit diagram showing a typical prior art lamp circuit.
BEST MODE OF CARRYING OUT THE INVENTION
Referring now to the drawings and FIGS. 1 and 2 in particular, there is shown a lamp failure detecting device according to one embodiment of the invention for detecting the failure of any of a number of lamps L.sub.1 -L.sub.n connected in series (FIG. 2) which are powered by a supply source E having a commercial frequency. FIG. 1 is a circuit diagram on enlarged scale of a lamp L.sub.1 having a filament 10. A short-circuitng circuit 11 is provided for giving a short circuit between the opposite terminals of the lamp filament 10. The circuit 11 is conventional, including a switch SW.sub.1 which operates to close the circuit 11 in the event of lamp failure. The circuit 11 is connected to a power line P.sub
REFERENCES:
patent: 3417310 (1968-12-01), Hill
patent: 3898913 (1975-08-01), Kopernik
patent: 3964040 (1976-06-01), Behl
patent: 3995262 (1976-11-01), France
patent: 4376910 (1983-03-01), Peslier
patent: 4527095 (1985-07-01), Herring
Disconnection Indicating Method, Toshio Kasahara, Document No. 62-16000, Japan, published Apr./10/87.
Futsuhara Koichi
Kato Masakazu
Adams Bruce L.
LaRoche Eugene R.
Nippon Signal Co., Ltd.
Wilks Van C.
Zarabian A.
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