CA1320246C - Emergency lighting system having remote test capability - Google Patents

Abstract

Case 870223 EMERGENCY LIGHTING SYSTEM
HAVING REMOTE TEST CAPABILITY

Nikunj Shah Abstract of the Disclosure An emergency lighting system includes a lighting unit having a battery which is kept in a charged condition in the presence of voltage on a power line to which the unit in connected. Upon loss of voltage, the battery is caused to discharge into a pair of flood lamps to provide emergency illumination to an area surrounding the unit. To provide for periodic testing of the unit without requiring the user to actuate a switch on the unit the system includes a radio frequency receiver in the unit which responds to signals generated by a hand-held radio frequency transmitter actuated by the user. A two stage battery charging circuit and a low voltage lamp cut-off circuit are included in the lighting unit for improved battery life.

Description

SPECIFICATION i 3 ~ ~ 2 4 6 Back~round 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 emergency lighting to commercial and resi-dential buildings in the event of AC line failure. Typi-cally, such units are mounted high on the wall of a hall orstairway, and are connected to the AC line supplying light-ing 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 bat-tery and model TC6N and A6N nickel cadmium emergency light-ing units manufactured by Teledyne sig seam of Crystal ~ake, Illinois. Such units are available with a variety of different lighting heads to accommodate different lighting requirements, as well as with a variety of different bat-~0 tery voltages and capacities to accornrnodate differentlighting requirements.
To be certain that emergency lighting units are providing the desired degree of protection it is desirable that they be peri.odically tested, and in rnany installations such tests are established as a regular procedure. Unfor-tunately, to test prior ernergency lighting units it was ne-cessary for the user to individually actuate a test button '~

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- ~20~46 on each unit housing to momentarily interrupt the AC line, and then observe after a short time dela; the illumination of the unit flood lights. Since the housings of such units were often located in high relatively inzccessible locations, testing was often been an ard~ous, time-consuming task, particularly where a large number of emergency ligbting units had to ~e tested.
Accordingly, the need has existed for an emergency lighting unit which ca~ be quickly and ec,onomically tested, without the need to gain access to the unit housing. The present invention satisfies this reguire~ent through the provision of a radio frequency test lin~, actuated by a Rmall hand-held battery-operated radio transmitter.
A further requirement of emergency lighting units 5 i8 that tho unit provide a long shelf life prior to actual use, and a long period of illumination when called into use.
Th¢ pre~ent lnvention ~eets this requlre~ent through the provision of a variable-rate battery charging circuit which mal~tains the battery in an optimum state of charge, and a low-voltage cut-out cizcuit which prevents exces~ive discharge of the batte.y when the lighti~g unit is called into use.
SummarY of the ~nvention An emergency lighting system operable upon 10B8 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 1 3 ~ 3 h '1 0 battery to the flood lamp upon loss of voltage on the monitored conductor, test circuit means including a re-ceiver 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 emergen-cy lighting unit operable upon loss of voltage on a moni-tored AC line, which includes at least one flood lamp, bat-tery 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 means 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 pro-gressively decreasing charging current at a constant vol-tage is supplied to the battery, the charging means oper-ating in the second mode upon the voltage across the bat-tery reaching a predetermined threshold level.
The invention is further directed to an ernergency lighting unit operable upon loss of voltage on a monitored AC line, which includes at least one flood lamp, battery rneans for powering the flood lamp, and switch means for connecting the battery 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 ~32~2~6 across the battery falling below a predetermined minimum threshold level.
Brief Description of the Drawinqs 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:
Figure 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.
Figure 2 is a perspective view of the hand-held transmitter utilized in the system of the Figure 1.
Figure 3 is a simplified functional block diagram of the emergency lighting unit shown in Figure 1.
Figure 4 is a sirnplified electrical schernatic diagram of the emergency lighting unit of Figures 1-4.
Figure 5 is a simplified electrical schematic diagram for an alternate remote test circuit for use in the emergency lighting unit of Figures 1-4.
Figure 6 is a simplified electrical schematic diagram of another alternate circuit for use in the emergency lighting unit of Figures 1-4.

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132~2~6 Figure 7 is a plot of certain current and voltage parameters associated with the emergency lighting unit of Figures 1-4.
Descri~tion of the Preferred Embodiment Referring to the figures, and particularly to Figure 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 trans-mitter 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 transmitter unit 12 is intended for hand-held use and is operated by the user at a remote location some distance from the wall-mounted lighting unit 11.
In accordance with conventional practice, lighting unit 11 includes a lighting head assembly consisting of a pair of low-voltage flood lamp assernblies 13 and 14. The a qemblies, which may be conventional in construction, are pivotally and swivelably mounted on the top surface of a housing 15, and are adjustable so that the emergency lighting provided by these assernblies can be directed as required. Housing 15 includes on its front panel a control panel 16 containing various indicator lamps and switches associated with operation of the lightiny unit. In particular, control panel 16 may include an amber POWER ON
indicator lamp 20, a red FAST CHARGE indicator larnp 21 and a 13202~
green TRICKLE CHARGE indicator lamp 22. Panel 16 may further include a momentary contact test switch 23 and a head cut-off switch 24 for removing power to flood lamp assemblies 13 and 14 in the event that AC line power has failed and emergency illumination is no longer required.
Test switch 23 functions to initiate a test of the emergency lighting unit by simulating the interruption of AC line power to the unit. A volt meter 25 may be provided on control panel 16 to indicate battery condition to the user.
The emergency lighting unit 11 is connected to an AC line by a power cord 17, although in practice this connection may be established instead by hard-wiring of the unit directly to the AC line.
Referring to Figure 2, the hand-held test-initiating transmitter unit 12 is seen to include a slidable cover 25 which can be slided by the user to expose an actuator button 26 by which the user can initiate a radio frequency transmission to emeryency lighting unit 11.
Transmitter unit 12 may be entirely conventional in design and construction, and rnay employ conventional oscillator, amplifier and modulating circuitry to provide an encoded radio frequency signal to the emergency lighting unit.
Within the lighting unit, a radio frequency receiver 27 (Figure 1) of conventional design and construction and capable of receiving and responding to the signal trans-mitted by transmitter unit 12 is provided. For ease in 132~246 carrying tra~smitter 12, a key ring type chain dev.ce 28 may be provided in conjunction wit~ an inpact resistant plastic housing 29 of conventional construction. In practice, housing 29 ~ay be brightly colored to help preve~t los~ or inadvertent camage of the trans~itter unit, and svitch 26 may be a mo~entary contact type switch spring-biased to an off position 80 that the tran$nitter cannot be inadvertently left on.
Referring to the simplified functional block diagram of ~igure 3, the emergency lighting unit 11 is seen to include qenerally a power supply 30 operable fro~ the monitored AC line through the connecting power card 17. As shown, the AC line connection is completed through test swltch 23 and test receiver 27. Thus, the connection can be lnterrupted by user actuation of test switch 23 o~ control panel 16, or by user actuatlon of test receiver 27 by mean~
of the remot~ test lnitlating tsansmltter unit 12. Either action has t~e effect of removing AC llne power to power ~upply 30 and thereby initatlng a power 1088 condition within lighting unit 11. An antenna 31 may be provided in con~unction ~ith remote te~t re~eiver 27, eitber vithin or external to housing 15.
Pover supply 30 provi~es, in accordance vith another a~pect of the invention, both unregulated ~igh current and regulated low curre~t outputs. The regulated low current output is connected to a standby battery 32 through tbe ~ormally open contacts of a llghtlng control 132~2~6 relay 33 and an ammeter 25. The normally open contacts of relay 33 connect battery 32 to flood lamps 13 and 14 of the head assembly, so that upon energi~ation of relay 33 lamps 13 and 14 are illuminated by battery 32.
When relay 33 is deenergized charging current is supplied to battery 32 from the regulated low voltage output of power supply 30. To provide for a higher unregulated current to battery 32 when battery voltage is low, the bat-tery is connected to the high current unregulated output of power supply 30 through the normally-closed contacts of a charge control relay 34. The normally-open contacts of relay 34 are connected to a status indicating circuit 35 which causes an appropriate one of indicator lamps 20-22 on control panel 16 to be illuminated in accordance with the charging mode of the battery.
The operation of relay 33 is controlled by a loss of AC line detection circuit 36 which monitors a separate isolated output of power supply 30 and applies battery voltage to relay 33 upon loss of the isolated output. Relay 2~ 33 .is further controlled by a low battery voltage detectlon circuit 37 which monitors the terminal vo].tage of battery 32 by means of a voltage divider network 38 cmd interrupts the ground return of the relay upon the terrninal voltage of the battery falling below a predetermined minimum threshold level. Head cut-off switch 24 is provided in this circuit, in accordance with another aspect of the invention, to enable a user to interrupt operation of flood lamps 13 and -~ 1320246 14 if desired. Thus, relay 33 is energized and the flood lamps are illuminated by battery 32 upon loss of AC line voltage by detection circuit 36, and remain illuminated during such voltage loss until the terminal voltage of battery 32 as detected by detection circuit 37 results in relay 33 being deenergized.
The operation of the charge control relay 34 is controlled by a charge rate control circuit 40 which init-iates a low charge rate upon the battery terminal voltage as sensed by a voltage divider 41 rising above a predetermined maximum threshold level. At this time, the connection to the high current unregulated output of power supply 30 ls interrupted and charging continues at the relatively lower charging rate provided by the voltage regulated output of the power supply. A connection to the normally-open contact of relay 34 provides a hysteresis or latching function to the action of charge control circuit 40 so that the relay will remain in the low current regulated mode once battery voltage ha~ exceeded the predetermined maximum threshold, notwithstanding line voltage variations.
Referring to the simplified electrical schematic diagram of Pigure 4, power supply 30 may include a transformer 42 having a primary winding 43 and a pair of secondary windings 44 and 45. AC line power is supplied to primary winding 43 through normally-closed contacts 46 of a relay 47 within test receiver 27, which includes conventional receiver circuitry 48 powered by the AC line.

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1~202~6 A conventional fuse 49 is provided in series with the line connection to protect the system in the event of a malfunction, and the user-actuated te~t svitch 23 i6 provided in series with the line to faciliate user testing or simulation of a voltage loss as previously de~cribed.
With this arrangement, upon actuation of test sw.itch 23 or upon receipt of a test ~ignal by receiver circuitry 48, AC
line power is removed fro~ primary windiQg 43.
To provide a relatively high current unregulated source for charging battery 32 secondary Yinding 44 i8 connected to the input ter~inal~ of a conventional bridge rectifier network 50. The negative polarity output terminal of this network is grounded, and the positive polarity output ter~inal is connected by a filter capacitor Sl to ground to provide on an output line 52 a ~ource of unregulated charging curre~t. An additional i~olated positive polarity output i~ provided on ~ line 53 by a pair of dlode~ 54 and 55 connected back-to-bac~ across secondary wlndlng ~4.
A relatively lov voltage regulated output ~ 8 provided by a second full ~ave rectifier ~etwork 56 connected zcross secondary wlnding 45. She negative polarity output termlnal of this network i8 grounded and the positivo polarity output terminal 18 co~ected by a filter capacitor 57 to ground and to the input of a voltage rogulator 58. In accordance wlth conventional practlce, a voltage divlder comprising a fi~ed resi~tor 59 and a variable resistor 60 are connected between the output of the regulator and ground to provide a control voltage for opera-tion of the regulator. A capacitor 61 connected between the regulator output and ground provides additional filtering for the regulated direct current produced by the regulator, which is available on a line 62. An isolated negative pol-arity output is developed on a line-63 by a pair of diodes 64 and 65 connected back-to-back across secondary winding 45.
The regulated output of power supply 30 appearing on line 62 is supplied to battery 32 through ammeter 25, the normally-closed contacts of relay 33 and a fuse 66 provided to protect battery 32 in the event of a circuit malfunction.
In the event of loss cf AC line voltage relay 33 is actuated lS to cause battery 32 to be connected to the parallel-connected flood lamps 13 and 14. Actuation of relay 33 is accomplished in this event by application of a direct current rom battery 32 through NPN transistors 70 and 71 to the winding 72 of relay 33. In the presence of line voltage transistor 70 is biased into cut-off by the negative polarity voltage developed on line 63, which is applied to the base of the transistor through an isolation resistor 73.
Upon loss of AC line voltage the negative bias is removed, and a positive bias is applied to the base of the transistor from battery 32 through a voltage divider comprising resistors 74 and 75 to drive the transistor into saturation.
A capacitor 76 connected between and base and ground .q,~

132~246 provides a desirec time delay to the transition betveen cut-off and ~atur~ed ~tates of tr2nsistor 70 Tran~istor 71 is normally biased into saturation ty a positive pola-ity voltage developed by battery 32 In particular, this i provided by ~cltage divider 38 which i~
~een to comprise a zener dlode 77 and a pair of re~istor~ 78 and 79 connected ~etween the po~itive terminal of the ~attery and ground The voltage c~vi~ion pro~ided by voltage diYidor 38 i~ such that transistor 71 biased into ~aturatlon 80 lonç as sufficient voltage remains acro~s the battery to oporate flood l~mps 13 ~nd 14 w$thout harm to the ~attery An additional resistor 8~ connected between the flood lamps and the voltage div$des modlfies tb- inlmum thr-shold voltag- l-v-l required to malntain satur~tion in transl~tor 71 during operatlon of the flood l~ ps by r-du¢lng the ~ on factor of tk- voltago dl~lder, ~-sultlng ln tho a7pllcatlon of a ~reat-r voltag- for a given battery ter~nal voltage to transistor 71.
The heac cut-off svltch 24 provlded in series with the base of tran~i~tor 71 provlde~ an effectl~e lov-current point at which the oporatlon of relay 33 can be interruptod ~lthout swltchl*g ~ea~y curront lc~d~ Actuatlon of cut-off wltch 24 resultJ in relay 33 belc~ deenergized, allowlng the user to termi~ato operatlon of flood lamp~ 13 and 14 in 2S the event of an estended pow-r lo~ whore em-rg~ncy llghtlng i~ no ~onger required To thl~ ecd, head cut-off switch 24 ~ay be bl-6table ~ereby the swltc~ can be actuated by the ~32~2~6 user to remain in an open state for continued non-operation of the flood lamps.
When relay 34 is not energized the unregulated output of power supply 30 on line 52 is applied to battery 32 through the normally-closed contacts of the relay.
However, when the terminal voltage of battery 32 rises to a predetermined threshold voltage, as determined by voltage divider 41, an NPN transistor 81 is caused to conduct and the winding 82 of relay 34 is energized by the voltage regulated output of power supply 30 on line 62. To this end, the voltage divider 41 connected between the positive terminal of battery 32 and ground includes a zener diode 83, a fixed resistor 84 and a potentiometer 85. Depending on the setting of potentiometer 85, a portion of the battery voltage is applied to the base of transistor 81 such that conduction is established through the transistor when the battery voltage has risen above the threshold level. A
hysteresis or latching function is provided for this transition by a diode 86 and resistor 87 which apply battery voltaye present at the norrnally-open contact of relay 34 upon energization of the relay. A back-b:iased diode 88 and capacitor 89 provide transient suppression at relay winding 82, as does a diode 90 connected across winding 72 of relay 33, Thus, upon the voltage across 'oattery 32 rising to the predeterrnined threshold level, transistor 81 is biased into saturation and windiny 82 is eneryized to cause relay 34 to disconnect the unreyulated relatively hiyh voltaye hiyh ~132a246 eurrent output on line S2 from the battery An indication of the charging mode of the emergene~ lighting _ystem is provided by indicator lamps 20-22 In particular, the amber indicator lamp 20, S indicati~g the pre~ence of AC voltage, i8 oonnected between line 53 and ground and i~ lighted whenever ~upply 30 is powered m e operation of th- red indieator lamp 21, indieating a fast eharge, and the green indicator lamp 22, lndicating a trickle eharqe, is eontrolled by an NPN
transistor 91 having colleetor and emitter electrodes eonneete~ aeros~ indieator lamp 21 and its baee conneeted to the nor~ally open eont-cts of relay 34 by a resistor 92. In the event of a fast eharge oondition, when relay 34 is not nerglz-d, translator 91 ia non-¢onduetivo and lndicator laap 21 la lllu lnat-d through a series-eonneeted reslstor 93 by esrr-nt on llne 53. 81ne- the r-aiatanee of l~mp 21 la ueb higher than tb- r-al~tanee of resl~tor 93, rel-tlv-ly llttl~ voltag- la doveloped aeros~ the resla~or and lamp 22 do-~ not llght. Bowever, upon aetuatlon of r-lay 3~ eoneurr-nt with a triekle ehargo eondltion, tranalator 91 18 bla~ed into ~aturatlon to shunt lndie~tor lamp 21 Indieator lamp 22, whieh i8 eonn-eted aero~a realator 21, now ree-lves the voltage pre8ent on llne 53 and aeeordlngly 1~ eau~od to illumlnate Aa ahown ln ~lgur- 5, the remote test functlon may alte~natively be aeeompllahed by utlllzlng a bi-stable relay 94 enorgized by roeeiv-r cireuits 48. With thls arrange-`- 1320246 ment, power to the lighting unit is interrupted with al-ternate actuations of the radio receiver, so that the test function is initiated with a first momentary RF signal and terminated with a second momentary RF signal. In this way, the test function can be actuated as long as desired by the user. This is particularly useful where optional remote flood lamps 95 are used at a location distant from the lighting unit.
As shown in Figure 6, it is possible to have a test function of fixed duration following a momentary RF
signal by utilizing two relays 96 and 97 and a delay circuit 98. Upon receipt of a momentary RF signal receiver circuits 48 actuate relay 96, which thereafter remains actuated by reason of an additional pair of contacts connected in a holding circuit. After a predetermined time period, delay circuit 98 momentarily actuates relay 97, which opens the holding circuit of relay 96 and terminates the test period.
While a radio frequency test link has been shown for remote actuation of the emergency lighting system from a remote location, it will be appreciated that other types of wireless test links can be utilized. For example, it would be possible to substitute an infrared light transmitter unit for the radio freguency transmitter unit 12 and an infrared receiver for the radio fre~uency receiver 48 whereby the same test function could be performed by the user within line-of-sight of lighting unit 11. In this instance, it is contemplated that an infrared detector would be rnounted on X

housing 15, preferably on the front panel thereof, to provide for reception of the radiated infrared beam.
Also, it is contemplated that an ultrasonic transmitter could be substituted to transmit an ultrasonic sound beam which would be intercepted by a conventional ultrasonic receiver within housing 15 to accomplish the remote test function. In this case, an ultrasonic trans-ducer would be mounted on housing 15, preferably on the front panel thereof, to permit a performance of the test function within acoustic range of the emergency lighting unit 11.
The dual-mode charging function provided in of emergency lighting unit 11 provides optimum protection for nickel-cadmium and lead acid batteries, which are typically provided in a sealed configuration requiring minimal maintenance on the part of the user. By reason of the relatively high initial charging current such batteries are quickly brought up to a safe charge level following di~charge during a voltage loss. ~owever, as the battery terminal voltage reaches a predetermined threshold level at which such charging cannot be continued, a constant-voltage i~ maintained across the battery terminals whereby a progressively decreasing charge occurs as the battery continues to approach a fully charged condition. This is shown in Figure 7, wherein, in the high current mode, upon initial power up of the lighting unit the voltage 100 across the battery is seen to rise as the charging current 101 applied to the battery decreases. Eventually a vo~ta Q 4 6 level vl is reached at which relay 34 is actuated to condition the lighting unit to the low current constant voltage mode, and the battery voltage is thereafter main-tained at a constant voltage V2 by a variable charging current which gradually decreases to a low trickle level.
Thus, as a result of the constant voltage maintained on line 62 by power supply 30 the charging rate tapers off as bat-tery voltage increases with increasing charge state. This provides recovery for the battery in a minimal time without compromising battery longitivity.
In one commercial embodiment of the invention the flood lamps 13 and 14 of the illumination head and battery 32 are rated at 6 volts. Secondary winding 44 provides 7.5 volts AC, resulting in a voltage of approximately 7 volts on line 52 with a current ranging from 5 to 7 amperes. Secon-dary winding 45 provides 11 volts AC at 2 amps, resulting in a regulated voltage on line 62 of approximately 6.5 volts at up to 3 amperes. For a lead acid battery, battery capaci-tieS up to 100 amperes may be provided up to 12-1/2 hours of illumination in the event of aC power failure. For a nickel-cadmium battery, battery capacities of up to 60 amps may be provided to obtain an illumination period of up to 6-1/2 hours.
By reason of the low voltage head cut-off circuit operation of the lamps is interrupted in the event the charge state of the battery becomes so depleted during X

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operation as to risk permanent damage to the battery. This is done by monitoring the terminal voltage of the battery, and interrupting the connection to the flood lamps in the event of the voltage falling below a minimum level. The provision of a test switch in this circuit provides an ef-ficient means for interrupting operation of the flood lamps in the event of an extended loss of AC voltage when emerg-ency illumination is not required.
While a particular embodiment of the invention has been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made therein without departing from the invention in its broader aspects, and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.

Claims

The embodiments of the invention in which an ex-clusive property or privilege is claimed are defined as follows:

1. A stand-alone emergency lighting unit oper-able upon loss of voltage on a monitored AC line, and in conjunction with an external hand-held transmitter unit pro-viding consecutive user-initiated first and second momentary wireless test signals defining a desired test period, compri-sing:
a housing adapted for mounting on a supporting sur-face;
illumination means including at least one flood lamp for providing illumination in the vi-cinity of the housing;
rechargeable battery means in said housing for pow-ering said flood lamp;
rectifier means within said housing operable from the monitored AC line for recharging said battery means, said rectifier means including a supply circuit connected to the monitored AC line;
monitoring circuit means within said housing for monitoring the application of AC line current to said rectifier means and for producing a control effect in the absence thereof;
switch means within said housing responsive to said control effect connecting said battery means to said flood lamp to power said lamp upon loss of voltage on the monitored AC
line;

bistable circuit means including detector means within said housing responsive to said con-secutive first and second externally gener-ated momentary test signals for interrupting the application of line current to said recti-fier means upon receipt of said first momen-tary test signal whereby said battery is caused to supply current to said illumination means, and for restoring the application of line current to said rectifier means upon receipt of said second momentary test signal whereby the supply of battery current to said illumination means is discontinued, said mom-entary test signals thereby providing said desired test period; and said bistable circuit means in the absence of said second momentary test signal restoring the ap-plication of line current to said rectifier means following a predetermined period of time after said first test signal whereby the supply of battery current to said illumina-tion means is discontinued, said first test signal thereby automatically providing a de-fault test period of finite duration.