Abstract:
An improved flush-mount emergency light fixture ( 10 ) is provided having a housing ( 12 ) adapted for placement in a wall or ceiling aperture ( 20 ), an internal illumination assembly ( 16 ) and a selectively movable cover ( 14 ), in order to provide illumination during an emergency condition. The fixture ( 10 ) includes a servo-motor ( 74 ) and an operator ( 78 ) for controlled movement of the cover ( 14 ) between a closed position and a deployed illumination position. A floating hinge ( 54 ) couples the cover ( 14 ) to housing ( 12 ) and allows the cover to both pivot and translate relative to the housing ( 12 ) during cover movement.

Description:
RELATED APPLICATION 
     This Application claims benefit from the Provisional Patent application Ser. No. 60/159,256, filed Oct. 13, 1999, and entitled SERVO-CONTROLLED CONCEALED EMERGENCY LIGHT FIXTURE, the teachings of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is broadly concerned with an improved emergency light fixture which is designed for essential flush mounting in a wall or ceiling but which is automatically deployed to provide illumination in the event of an emergency. More particularly, the invention pertains to such an emergency light fixture which includes a housing for an illumination assembly with a selectively openable cover; the cover is movable through a servo-motor and crank, thereby completely eliminating the need for limit switches in the fixture. A special cover hinge also causes the cover to both pivot and translate during movement thereof. 
     2. Description of the Prior Art 
     Office buildings and other similar structures are universally provided with emergency lighting fixtures designed to illuminate in the event of a fire or other emergency. For example, battery-operated fixtures are located in stairwells and are often surface-mounted. While these units do serve an important purpose, they are considered unsightly and many designers hesitate to use them in formal offices or other settings where aesthetics are a consideration. 
     It has also been known to provide flush-mounted emergency light fixtures having a pivotal cover. In such units, an illumination assembly is located in a recessed housing or the like and when an emergency occurs, the cover is pivoted open and the recessed lamps are illuminated. Deployment of these prior flush-mounted emergency lighting fixtures is typically achieved by means of an electric motor and various limit switches to stop the operation of the cover in both the open and close directions. However, upon failure of the limit switches, these units tend to self-destruct and become unusable. An additional problem with these prior units is that it is difficult to provide a cover opening mechanism which will assure that the cover opens in a smooth, reliable and controlled way even after extended periods of non-use. 
     There is accordingly a need in the art for an improved emergency lighting fixture which eliminates all potentially troublesome limit switches and gives accurate and reliable cover movement at all times. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the problems outlined above, and provides an improved emergency light fixture of the flush-mounted variety. Broadly speaking, the fixture of the invention includes a housing adapted for placement in a wall or ceiling aperture and presenting an opening, with a shiftable cover movable between a closed position and an open position; an illumination lamp is located within the housing when the cover is in its closed position, but preferably is moved at least partially out of the housing when the cover is open. The overall fixture further includes an operating assembly coupled with the cover and lamp in order to selectively move the cover and operate the lamp. The assembly includes a servo-motor having an output, with an operator connected between the output and the cover for moving the cover towards its open and closed positions. A control circuit is also provided which is coupled with an emergency power source and connected with the servo-motor and lamp respectively. 
     In preferred forms, a pair of illumination lamps are provided, and these are connected to the cover in order to provide a gravity assist during cover opening and to insure that the full illumination power of the lamps is utilized. The cover is secured to the housing by means of a special hinge which causes the cover to both pivot and translate relative to the housing during cover movement. This special hinge comprises first and second hinge parts respectively connected to the housing and cover, with a hinge pin interconnecting the hinge parts; the first hinge part is connected with the housing in a floating manner and translates during cover movement by virtue of a slot/connector arrangement between the hinge part and housing. 
     Use of a servo-motor and appropriate control circuitry permits the cover to be accurately moved between its open and close positions without the need for limit switches, and the preferred floating hinge arrangement facilitates reliable cover control. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the preferred emergency light fixture of the invention, shown with the cover thereof in its closed position; 
     FIG. 2 is a perspective view similar to that of FIG. 1, but illustrating the cover in its open position during emergency use of the light fixture; 
     FIG. 3 is a vertical sectional view of the preferred light fixture of the invention, shown mounted in a ceiling and during deployment and use of the fixture; 
     FIG. 4 is a vertical sectional view similar to that of FIG. 1, but showing the fixture in its normal closed and inactive position; and 
     FIG. 5 is a vertical sectional view illustrating the fixture in its open and deployed position, and illustrating details of construction of the preferred cover hinge. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning now to the drawings, and particularly FIGS. 1-3, an emergency light fixture  10  in accordance with the invention broadly includes a housing  12 , shiftable cover  14 , an illumination lamp assembly  16 , and an operating assembly  18 . The fixture  10  is designed to be located in an opening  20  provided in a wall or ceiling  22 , so that the fixture is essentially flush-mounted to the wall or ceiling. The fixture  10  is normally in the position depicted in FIGS. 3 and 4 with cover  14  closed; however, in an emergency situation the cover  14  is opened and the lamp assembly  16  is activated to illuminate the lamps, thereby providing illumination to facilitate escape from a building or the like. 
     In more detail, the housing  12  is in the form of an open-bottom box, presenting front and rear walls  24 ,  26 , side panels  28 ,  30  and top wall  32 . The housing  12  thus defines a deployment opening  34  in opposed relationship with the top wall  32 . As best seen in FIG. 2, a generally U-shaped liner  36  is positioned within the housing  12  and includes front and rear segments  38 ,  40  respectively adjacent the housing walls  24 ,  26 , as well as a top segment  42  adjacent housing top wall  32 . The front and rear segments  38 ,  40  include laterally projecting flanges  44 ,  46  as best seen in FIG.  4 . Additional side flanges  48 ,  50  are connected to the liner flanges  44 ,  46 . Thus, the flanges  44 - 50  circumscribe opening  34  and abut the regions of wall or ceiling  22  adjacent opening  20 . Although not specifically depicted in the drawings, it may be preferable to incorporate a continuous flange in lieu of the flanges  44 - 50 , so as to permit the fixture to be mounted in essentially flush relationship to the wall or ceiling. 
     The cover  14  is a simple plate  52  which is of a size to abut the flanges  44 - 50  when the cover is in its closed position, and of course it also covers the opening  34  in this orientation. Cover  14  is secured to housing  12  via a specialized floating hinge  54 . In particular, the hinge  54  includes first and second hinge parts  56 ,  58  respectively coupled to the housing  12  and cover  14 . As best seen in FIG. 5, the hinge part  56  includes a pair of elongated slots  60 , with a bolt connector  62  extending through each slot  60  and coupled to liner segment  40 , in order to permit relative sliding movement of the hinge part  56  relative to the housing  12 . The hinge part  58  is fixed to the cover  14  by connectors  64 . The two hinge parts  56 ,  58  are interconnected by hinge pin  66  in the usual fashion. A pair of coil springs  67  are interconnected between the liner segment  40  and hinge part  56  (see FIG.  5 ), so as to bias the hinge  54  towards the cover-closed position. 
     The lamp assembly  16  includes a pair of adjacent lamp holders  68  each secured to the upper surface of cover plate  52  by mounts  70 . Each holder  68  receives a flood lamp  72 . 
     The operating assembly  18  is located within housing  12  and includes a conventional pulse proportional servo-motor  74  having a pivotal output  76 . As shown, the motor  74  is connected to liner segment  42  and depends therefrom. An operator  78 , comprising first and second pivotally interconnected crank arms  80 ,  82 , is connected between output  76  and cover  14 ; in particular, an upstanding attachment plate  84  is secured to the upper surface of cover plate  52  between the mounts  70  and pivotally receives the end of crank arm  82 . 
     The assembly  18  further includes a control circuitry  86  containing conventional circuit components which are operatively connected to the lamp holders  68  via leads  88 , and to motor  74  via lead  90 . Power source leads  92  from a battery or other emergency power source (not shown) extend through appropriate openings in the housing wall  24  and liner segment  32 , and form the power input to the control circuitry  86 . As will be readily understood by those skilled in the art, the control circuitry is designed, when the fixture  10  is in the normal inactive position shown in FIGS. 1 and 4, to illuminate the lamps  72  and activate servo-motor  74  when an emergency condition is sensed and the control circuitry is energized via the leads  92 . Moreover, when the fixture  10  is in the deployed condition depicted in FIGS. 2,  3  and  5 , the control circuitry is designed to extinguish the lamp  72  and activate motor  74  to close the cover  14  after an emergency condition is over. 
     The control circuit provides the motor  74  with operational signals generated by a dual timer IC. One timer output provides a repetitive pulse of preselected width to satisfy the servo when it is in the extreme cover open position, while the other timer output gives a repetitive pulse width proportional to the desired cover closed position. By this method, precise cover positioning is achieved without the need for costly and unreliable limit switches. 
     Power to the circuitry  86  is provided by two sources. An emergency power source or battery causes the fixture to open and illuminate when applied. A second power source provides the closure signal, which is applied for a period of not more than ten seconds, preferably 5±3 seconds. 
     In order for the fixture  10  to be used in insulated ceilings or walls, a normally closed resettable thermostat may be incorporated. The thermostat may be added to insure operation of the fixture when it would otherwise not deploy in the emergency mode. 
     Under normal or cover-closed conditions, the fixture  10  does not require power. Cover closure is maintained mechanically by virtue of the position of the operator  78 , which preferably stops at or beyond the point at which the cover  14  can be forced open, thus minimizing the possibility of inadvertent gravity opening of the cover  14 . 
     Upon activation via power applied to the emergency power input, the lamps  72  immediately illuminate and the circuitry  86  provides the “open” pulse, thereby causing the servo-motor output to rotate. As long as emergency power is applied, the circuitry  86  maintains the exact, cover full-open position of the servo-motor. The circuitry includes a potentiometer permitting setting of the servo to a desired cover full-open position. 
     Upon removal of emergency power and reapplication of normal power, the lamps  72  turn off and the servo control circuit  86  issues a pulse causing the servo-motor output  76  to rotate approximately 180° in the opposite direction, thereby causing the cover  14  to close. The cover close/normal power condition of the fixture  10  is preferably derived from the emergency source or battery using a time delay relay which provides a cover closure signal for a short period of time. Thus, when normal AC power is restored, the emergency power source is disconnected and the time delay relay times out to momentarily provide power to the fixture  10  so as to close cover  14 . At this point, the fixture  10  is back in its ready position and does not consume any power. 
     During deployment or closure of the fixture  12 , i.e., when the cover  14  is moved between its operative positions, the hinge  54  comes into play. In particular, the hinge  54  causes the cover to both pivot relative to the housing, and also to translate relative thereto. As can be appreciated, during cover movement between the closed and open positions, the cover translates away from the housing  12 , whereas during closure the cover translates towards the housing. Such translatory movement is afforded by virtue of the sliding and floating connection provided by the slots  60  and connectors  62  described previously.