Emergency lighting unit having remote test capability

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BACKGROUND OF THE INVENTION

The present invention relates to emergency lighting systems, and more particularly to an emergency lighting unit having a remote test feature and improved circuitry for prolonging battery life.

Emergency lighting units have come into wide use for providing energency lighting to commercial and residential buildings in the event of AC line failure Typically, such units are mounted high on the wall of a hall or stairway, and are connected to the AC line supplying lighting in that hall or stairway so as to provide lighting to the area upon loss of power. Examples of such units in commercial use are shown in the model TC6L lead acid battery and model TC6N and A6N nickel cadmium emergency lighting units manufactured by Teledyne Big Beam of Crystal Lake, Ill. Such units are available with a variety of different lighting heads to accommodate different lighting requirements, as well as with a variety of different battery voltages and capacities to accommodate different lighting requirements.

To be certain that emergency lighting units are providing the desired degree of protection it is desirable that they be periodically tested, and in many installations such tests are established as a regular procedure. Unfortunately, to test prior emergency lighting units it was necessary for the user to individually actuate a test button on each unit housing to momentarily interrupt the AC line, and then observe after a short time delay the illumination of the unit flood lights. Since the housings of such units were often located in high relatively inaccessible locations, testing was often been an arduous, time-consuming task, particularly where a large number of emergency lighting units had to be tested.

Accordingly, the need has existed for an emergency lighting unit which can be quickly and economically tested, without the need to gain access to the unit housing. The present invention satisfies this requirement through the provision of a radio frequency test link, actuated by a small hand-held battery-operated radio transmitter.

A further requirement of emergency lighting units is that the unit provide a long shelf life prior to actual use, and a long period of illumination when called into use. The present invention meets this requirement through the provision of a variable-rate battery charging circuit which maintains the battery in an optimum state of charge, and a low-voltage cut-out circuit which prevents excessive discharge of the battery when the lighting unit is called into use.

SUMMARY OF THE INVENTION

An emergency lighting system operable upon loss of voltage on a monitored AC line includes an illumination head comprising at least one flood lamp, a rechargeable battery for powering the flood lamp, switch means for connecting the battery to the flood lamp upon loss of voltage on the monitored conductor, test circuit means including a receiver operable to activate the switch means, and remote transmitter means for actuating the receiver means to activate the test function.

The invention is further directed to an emergency lighting unit operable upon loss of voltage on monitored AC line, which includes at least one flood lamp, battery means for powering the flood lamp, and switch means for connecting the battery to the flood lamp upon loss of voltage on the monitored conductor. The unit further includes battery charging mean for supplying current to the battery, the charging means having a first operating mode wherein a generally constant current is supplied to the battery, and a second operating mode wherein a progressively decreasing charging current at a constant voltage is supplied to the battery, the charging means operating in the second mode upon the voltage across the battery reaching a predetermined threshold level.

The invention is further directed to an emergency lighting unit operable upon loss of voltage on a monitored AC line, which includes at least one flood lamp, battery means for powering the flood lamp, and switch means for connecting the batery means to the flood lamp upon loss of voltage on the monitored conductor. User-actuable head cut-off means are provided for interrupting the connection between the battery and the flood lamp upon the voltage across the battery falling below a predetermined minimum threshold level.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims The invention, together with the further objects and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings, in the several figures of which like reference numerals identify like elements, and in which:

FIG. 1 is a perspective view of an emergency lighting system constructed in accordance with the invention showing a wall-mounted emergency lighting unit and a hand-held transmitter for initiating testing of the system.

FIG. 2 is a perspective view of the hand-held transmitter utilized in the system of the FIG. 1.

FIG. 3 is a simplified functional block diagram of the emergency lighting unit shown in FIG. 1.

FIG. 4 is a simplified electrical schematic diagram of the emergency lighting unit of FIGS. 1-4.

FIG. 5 is a simplified electrical chematic diagram for an alternate remote test circuit for use in the emergency lighting unit of FIGS. 1-4.

FIG. 6 is a simplified electrical chematic diagram of another alternate circuit for use in the emergency lighting unit of FIGS. 1-4.

FIG. 7 is a plot of certain current and voltage parameters associated with the emergency lighting unit of FIGS. 1-4.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring the the figures, and particularly to FIG. 1, an emergency lighting system 10 incorporating the features of the present invention is seen to include a wall-mounted lighting unit 11 and, in accordance with one aspect of the invention, a remote hand-held battery-operated transmitter unit 12 by means of which the lighting unit can be tested from a remote location, without user access to the unit. As shown, the remote