Abstract:
A luminaire motorized shade or douser mechanism includes a lamp mounted within a reflector and a motorized shade unit that opens and closes in front of the lens of the reflector. The shade unit includes a motor, two rollers, two guide cables, a sheet of opaque flexible material or fabric, and an aluminum frame. The motor drives the roller to run the shade in front of the lens to cover it and also to uncover. The motorized shade or douser mechanism is used to effectively block the light emitting from the lamp and create a condition whereas no light leaves the lens of the luminaire.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a remotely operated, powered shade or douser device mounted to the face of a light fixture so it can be moved across a lens to cover it. 
     Lighting devices with incandescent or arc discharge lamps have been provided with reflectors for many years. It is often desired to have an electromagnetic radiation source (a lamp) that radiates electromagnetic radiation in the visible spectrum (light). This combination of the lamp and the reflector is used to provide the lighting for sports arenas, sports stadiums and other commercial and industrial application. 
     In many applications, the electromagnetic radiation is derived from a plasma arc formed within an electromagnetic transmissive envelope or arc tube. One form of such an arc discharge lamp is a metal halide lamp. In such lamps, the arc is ignited between two electrodes placed at opposite ends of the electromagnetic transmissive envelope. These electrodes define an envelope axis and are connected to a power supply, which supplies the proper voltage and current for starting and operating the lamp. When power is removed from an operating metal halide lamp, it requires approximately fifteen minutes to re-strike, using normal voltages, and an additional five minutes to reach a stable color temperature and light output. 
     In certain lighting venues, such as arenas or stadiums, it is desirable to have the entire lighted area go dark. Such instances are used for player introductions, half-time shows, and special events. Prior applications have used a special instant re-strike lamp and ignitor system, which hits the system with a large voltage pulse to re-ignite the lamp. Even though it is called an “instant” re-strike system, this system takes several minutes for the light to come back to a full luminous output and full color rendering. 
     Other prior applications have used a mechanical device consisting of motor driven metal louver blades or clam shell devices that are moved into position in front of the lamp and reflector system to effectively block the transmission of light. This type of application can interfere with the projected beam of light causing a depreciation in light output which requires a higher total connected load to provide effective lighting levels. This type of application may also require more clearance around the luminaire to effectively mount the luminaire and shutter device such that there is no interference with surrounding fixtures. 
     The present invention arises from the fact that the instant re-strike system is lacking in several areas and the realization that the motorized metal louver blades cause a depreciation in light levels and require more mounting space. 
     SUMMARY OF THE INVENTION 
     The present invention includes a reflector and typically an arc discharge lamp mounted in the reflector, a frame and a motorized shade or douser mechanism. The shade or douser material is rolled onto a top roller with a reversible motor to an open position, increasing the tension of a bottom spring loaded take-up roller via one or more cables. When the motor is reversed, the tension in the spring on the bottom roller causes the rolled or coiled shade or douser to unwind and thus, the bottom roller and cables pull the shade or douser material in front of the lens. The cable, preferably an aircraft cable, is rolled onto the bottom roller until the shade or douser is in the closed position. The bottom roller continues to provide tension on the shade or douser when it is in the closed position, to hold the material taut. 
     The design also includes a bottom to top or a side to side application. The fabric used is a heat resistent material with a bar sewn into the fabric to provide even distribution of the torque required to roll and unroll the material. The edge of the shade or douser material is attached to stainless steel aircraft cable at two separate locations to ensure that the material stays within its frame. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front view of a luminaire having a motorized shade or douser of the present invention thereon, in a half closed position; 
     FIG. 2 is a side view of the luminaire with the motorized shade or douser in place; 
     FIG. 3 is a top plan view of the motorized shade or douser with the luminaire housing shown in cross section; 
     FIG. 4 is an isometric view of the motorized shade or douser in a half closed position; 
     FIG. 5 is a sectional view taken on line  5 — 5  in FIG. 3; and 
     FIG. 6 is a sectional view taken on line  6 — 6  in FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings, FIG. 1 is a front view of a motorized shade or douser  10  made according to the present invention mounted onto a luminaire housing  12 . The luminaire housing includes a reflector  14 , and a light source  16  arranged in a desired manner to project light out through a front lens  20  shown partially in FIG.  1 . The motorized shade or douser device includes a frame  22  that is made to mount onto the housing  12  in a suitable manner, such as with screw fasteners. The frame  12  surrounds the lens  20  and opening  21  covered by the lens  20 . 
     Frame  22  includes upright channel frame members  24  on opposite sides thereof that have longitudinally extending brush strips  26  (see FIG. 6) on the interior. One or more strips can be used. A lower channel cross frame member  28  joins the upright frame members  24 . The upper ends of the upright frame members support a roller assembly  30 , which is rotatably mounted on downwardly depending frame legs  32  that join the upright frame members  24 . The legs  32  support suitable bearings  36  to mount a shade or douser roller  38 . The roller  38  has a central drive shaft  40  extending through a tubular shell  42  (see FIG.  5 ). The shaft  40  is held in position in the shell with suitable end caps  44 . The drive shaft  40  is driven by a reversibly controllable motor  46  mounted onto a motor bracket  48  on the frame member  24  on one side of the frame. 
     A flexible material of fabric or douser sheet  50  forms a shade and is rolled onto the roller shell or tube  42 . The sheet  50  has a free control edge  52  on which a reinforcing bar  54  is mounted (see FIG.  5 ). At the lower end of the frame  22 , which is the side opposite from the roller  38 , a spring loaded take-up roller  58  is mounted on end brackets  60  which connect to the upright frame members  24 . The spring loaded take-up roller  58  is made like a window shade roller, and has opposite end caps that are mounted in the brackets  60 ,  60  as can be seen in FIG.  4 . The end portion  62  is flattened to a rectangular shape to hold one end of a torsion spring shown at  66  in FIG.  6 . The torsion spring  66  is on the interior of the tube  68  forming part of the take-up roller and has one end anchored to the tube. The tube  66  is mounted so it will rotate relative to the end portion  62  to create load in the torsion spring. The take-up roller has a pair of control cables  70  anchored thereon, which are wound on the roller  58  and which will unwind from roller  68  as the roller  38  is rotated by the motor  46  which creates tension on the cables  70 ,  70 . As the cables  70 ,  70  unwind, the spring  66  is loaded to tend to rewind the roller  58 . The spring  66  will pull on the cables  70 ,  70  and thus, the cables wind up as the motor  46  is stepped in reverse, to permit the shade or douser  50  to unwind from roller  38 . 
     The cross-member  28  has holes  28 A for providing a path for the cable  70 ,  70 . 
     The brush strips  26  that are provided on the frame members  24 , as well as on the bar  54  are for light sealing along the edges of the shade or douser  50 . The shade or douser material is an opaque fabric, that is of sufficient length to cover the entire lens  20  in the opening of the frame when the shade or douser is in its lowered position. 
     There is a pre-load on the torsion spring  66  so that with the shade fully extended covering the lens, the spring  66  still exerts a force on the shade or douser to keep it taut and in place to completely cover the lens  20 . No light from the light source  16  will pass through the shade or douser fabric and with all luminaires in an arena covered with the shade or douser, the arena can be made totally dark. 
     The motor  46  can be connected suitably to the shaft  40  through a drive coupling, and when the motor is driven clockwise when viewed in FIG. 4, for example, it will wind the opaque flexible material shade or douser  50  onto the upper roller assembly  30  and the cables  70 ,  70  will extend, placing greater tension on the shade or douser through torsion spring  66  of the take-up roller assembly  58 . The motor  46  is connected through an anti-reverse gear box or else is made so it will hold the shade or douser in position and tension on the cables  70  will not extend the shade or douser unless the motor is driven in reverse. When the motor  46  is energized through the programmed controls  76 , and the motor is driven in reverse through steps (it is preferably a stepper motor) in counterclockwise direction as shown in FIG. 4, the cables  70 ,  70  will extend the shade or douser  50  a desired amount over the lens  20 . In FIG. 4, the shade is half open, to provide a selected amount of light through the remaining portion of the lens  20 . The shade can be moved to close the lens opening as much as desired, including totally covering the lens opening. The brush strips that have been mentioned will provide light sealing along the edges. 
     The shade or douser  50  will be in alignment overlying the luminaire lens  20  so that it can be moved to completely block any light. As mentioned, when total darkness in an arena is desired for particular portions of a program, the shade or douser is used to block all light and the luminaire can remain on and does not have to be restarted. 
     The shade or douser assembly can be mounted on to existing luminaires by making the frame as a separate unit, as shown in FIG. 4, and merely supporting it with suitable screws, channels or extra brackets to the existing housings of luminaires. Compressible gaskets can be used for sealing light leaks. The shade assembly takes less room than motorized louver blades, and does not block any light when fully retracted. 
     The program control, indicated at  76 , can be a computerized program control, or a manually selected program that would be timed, after initiation, to open or close the shade or douser  50  as desired for obtaining the correct amount of illumination from each of the luminaires used. 
     The program control  76  can have a central program that would control a number of luminaires, each having a shade or douser assembly made according to the present invention. 
     The motorized shade or douser assembly provides a light-dimming system, that is easily used and programmed, and relatively simple to make and install. Further, it is essentially fool-proof, having few moving parts. 
     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.