Patent Publication Number: US-6902302-B2

Title: Gel scroller assembly for a luminaire

Description:
FIELD OF THE INVENTION 
   The present invention relates to an improved gel scroller assembly for a luminaire. 
   DESCRIPTION OF THE PRIOR ART 
   Luminaires, or lighting fixtures, including a housing containing a light source and an optical system are used for creating lighting effects for entertainment and architectural applications such as stages, studios, buildings, themed parks, churches, museums, restaurants and the like. A colored beam or wash of light is one frequently desired lighting effect. One widely used way to provide colored light is to use a gel, i.e., a translucent colored film, in the light path of a luminaire to add color to the emitted light. 
   In some luminaire systems, a single gel is simply mounted in the light path to provide a single color. For example, the gel can be supported in a frame that is mounted in a holder provided at the light exit opening located at the front of the luminaire. Although this is a simple and inexpensive way to achieve color, it is time consuming and inconvenient to change colors because the gel has to be removed and replaced with a new gel of a different color. 
   In order to automate the color changing process, motor driven gel changers have been provided. In one such approach, a gel scroller assembly is mounted to the front of the luminaire. The assembly includes a movable gel medium in the form of a gel scroll having a sequence of different colors wound around spaced drums or reels. The assembly is self contained, and includes a drive system with a motor for moving the gel medium to a selected position to achieve a desired color. 
   Self contained gel changers provide the capability of automated color changing, but are subject to disadvantages. Because the assembly includes the gel drive system with a motor and drive components, and perhaps also a cooling fan, it is expensive and cumbersome. Because of the cost of a self contained motor driven gel changer, the normal way to change gel media is to remove the original medium and install a new medium into the gel changer. In addition, power and control cabling must be provided for the gel changer. Known gel changers are attached to the luminaire with fasteners requiring tools and the use of both hands to attach or replace the gel changer. 
   SUMMARY OF THE INVENTION 
   A primary object of the present invention is to provide an improved gel scroller assembly for a luminaire. Other objects are to provide a gel scroller assembly including a scroller cassette that is inexpensive and light in weight; to provide a gel scroller assembly including a scroller cassette that can easily be mounted onto or detached from a luminaire with one hand and without tools; to provide a gel scroller cassette of low cost that permits the user to exchange the entire gel scroller cassette in order to change color arrays rather than to change the gel scroll in a single cassette; to provide a changer assembly for a light modifying medium that does not require the weight, expense or cabling requirements of a self contained changer unit; and to provide a gel scroller assembly overcoming disadvantages of gel scrollers used in the past. 
   In brief, in accordance with the invention there is provided a gel scroller assembly for a luminaire having a housing with a light beam exit opening. The scroller assembly includes a motor drive assembly mounted in the housing of the luminaire. The motor drive assembly includes a motor and a driver element driven by the motor and positioned adjacent to the exit opening. A scroller cassette includes a light passage. A latching system releasably attaches the scroller cassette in an operating position on the luminaire housing with the light passage aligned with the exit opening. The scroller cassette includes a gel scroll drive system for moving a gel scroll across the light passage. The drive system includes a driven member engaged by the driver element in the operating position of the scroller cassette. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     The present invention together with the above and other objects and advantages may best be understood from the following detailed description of the preferred embodiment of the invention illustrated in the drawings, wherein: 
       FIG. 1  is a front, side and top isometric view of a theatrical luminaire having a gel scroller assembly constructed in accordance with the present invention; 
       FIG. 2  is a side, front and top isometric view of the theatrical luminaire with the gel scroller cassette removed from the housing of the luminaire; 
       FIG. 3  is an isometric view of a top hat accessory that can be mounted in the accessory holder at the front of the scroller cassette; 
       FIG. 4  is an enlarged top, side and rear isometric view of the scroller cassette; 
       FIG. 5  is a top, side and rear exploded isometric view of components of the scroller cassette; 
       FIG. 6  is a greatly enlarged isometric bottom view of the scroller cassette latch member; 
       FIG. 7  is a fragmentary, top, side and front isometric view of components of the gel scroller assembly in the luminaire housing, with the top cover of the housing and the scroller cassette, except for one drum assembly and one drive pulley, removed; 
       FIG. 8  is an enlarged rear, top and side isometric view of the gel drive, fan and control board unit of the gel scroller assembly; 
       FIG. 9  is an exploded isometric view of the gel drive, fan and control board unit; 
       FIG. 10  is an enlarged exploded isometric view of components of the gel drive system; and 
       FIG. 11  is an elevational view of the gel drums and gel scroll of the scroller cassette. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Having reference now to the drawing, and initially to  FIGS. 1 and 2 , there is illustrated a luminaire generally designated as  20  provided with a gel scroller assembly generally designated as  22  constructed in accordance with the principles of the present invention. Although the illustrated preferred embodiment of the invention incorporates the gel scroller assembly  22 , media other than gel may be used to modify light from the luminaire  20 , for example an array of gobos, translucent light diffusing material or a dichroic medium. At least some of the aspects of the invention are applicable to assemblies including light modifying media other than gel. In addition, at least some aspects of the invention may be applicable to gel changer assemblies other than gel scrollers. 
   The luminaire  20  is a theatrical luminaire, capable of creating theatrical or theatre-like lighting effects for a variety of entertainment and architectural applications. However, features of the invention are useful with other luminaires. The luminaire  20  has a housing  24  with a front portion  26  having a light exit opening  28 . The housing  24  is supported for pan and tilt movement by a yoke assembly  30  including a base  32  and support arms  34 . A light source such as a lamp is contained in a rear portion  36  of the housing  24 , and an optical system between the light source and the exit opening  28  provides an optically formed light beam. The housing  24  is moved to aim a beam of light emitted through the opening  28  at a target or an area, such as a part of a building or stage or the like. 
   The housing  24  includes a base member  38  that serves as an optical rail for supporting and positioning components of the luminaire  20  such as the light source and elements of the optical system. A cover  40  is attached to the base  36  and cooperates with the base  36  to form an enclosure for the internal components of the luminaire  20 . 
   In accordance with the present invention, the gel scroller assembly  22  includes a gel scroller cassette  42  that is releasably attached to the housing  24 . The gel scroller assembly  22  also includes a drive, fan and control board unit  44  that is mounted within the housing  24  near the light exit opening  28 . The drive, fan and control board unit  44  remains in place within the housing  24  when the gel scroller cassette  42  is removed from the housing  24  as shown in FIG.  2 . An interface coupling assembly  46  connects the drive, fan and control board unit  44  to the gel scroller cassette  42  when the cassette  42  is mounted upon the housing  24  as seen in  FIG. 1  in order to provide mechanical power and cooling air flow to the cassette  42 . 
   The scroller cassette  42 , best seen in  FIGS. 4 and 5 , includes a frame  48 , preferably a stamped and formed sheet metal part, and a cover  50 , preferable a molded plastic part. The frame  48  and cover  50  are held together by fasteners  52  (FIG.  4 ). Aligned openings  54  and  56  in the frame  48  and cover  50  respectively define a light passage  58  that is aligned with the light exit opening  28  of the housing  24  when the cassette  42  is in place on the housing  24 . A beam of light emitted from the housing  24  passes through the light passage  58 . 
   When the scroller cassette  42  is installed on the luminaire housing  24 , a tab  60  of housing  24  is located slightly in front of the cover  50  of the cassette  42  (FIG.  1 ). An opposed pair of flanges  62  at the upper front corners of the cover  50  are generally coplanar with the tab  60 , and cooperate with the tab  60  to define an accessory mounting nest  64 . An accessory, such as the top hat light shield  66  seen in  FIG. 3 , can be mounted in the nest  64 . Shield  66  includes a circular cylindrical light guide  68  and a flat planar base  70 . The base  70  can be inserted down between the flanges  62  and behind the tab  60  where it is retained by a latch member  72  described below. Other accessories such as louvers or other types of light guides can be placed in the accessory mounting nest  64 . If the cassette  42  does not contain a gel, or if it is desired to add an additional gel, a individual gel frame can be placed in the nest  64 . 
   A base wall  74  of the cassette frame  48  is spaced above a bottom wall  76  of the cassette cover  50  to define a lower chamber  78 . A pair of side chambers  80  are formed between the frame  48  and the cover  50  at opposite sides of the light passage  58 . A drum assembly  82  is mounted in each side chamber  80 . Each drum assembly  82  includes a rotatably mounted drum  84 , an axle  86  and a lower end cap  88  above the base wall  74 . A drum drive pulley  90  is located below the wall  74  within the lower chamber  78  and is attached to the corresponding lower end cap  88  by a fastener  92  ( FIG. 5 ) extending through an opening  94  in the wall  74 . A bearing  96  reduces friction between the wall  74  and the end cap  88 . 
   A drive belt  98  located within the lower chamber  78  engages both drive pulleys  90  for simultaneous rotation of the spaced drum assemblies  82 . A scroll  100  or elongated web of gel material (shown only in  FIG. 11 ) is wound onto the drums  84  of the assemblies  82  and is wound back and forth between the drums as the drums are rotated. The scroll  100  typically includes an array of segments of different colors and a selected color can be placed across the light passage  58  by controlled rotation of the drum assemblies  82 . A gel tension torsion spring  102  mounted within one of the drum assemblies  82  ( FIG. 5 ) accommodates the variations in the effective diameters of the drums resulting from winding the scroll  100  on the drums  84 . 
   A latching system generally designated as  104  releasably attaches the gel scroller cassette  42  to the front portion  26  of the luminaire housing  24  over the light exit opening  28 . The light exit opening  28  is defined in a front plate  106 , and the latching system  104  includes a pair of catches  108  at the outer edges of the plate  106  at opposite sides of the opening  28  (FIG.  2 ). Frame  48  of the cassette  42  includes a pair of slots  110  that mate with the catches  108  (FIGS.  4  and  5 ). 
   The drive, fan and control board unit  44  includes a housing  112  and a base  113  attached by fasteners  114  ( FIG. 8 ) to the luminaire housing base member  38  at the front portion  26  of the housing  24 . A pair of positioning pedestals  116  are carried by the frame  112 . When the catches  108  are received into the slots  110  and the cassette  42  is lowered in place, pins  118  on the pedestals  116  are received into holes  120  in the base wall  74  of the frame  48 . The cassette  42  is accurately positioned in the side-to-side (X) and the forward-and-back (Y) planes by engagement of the catches  108  in the slots  110  and by engagement of the pins  118  in the holes  120 . The base wall  74  rests on the upper surfaces of the pedestals  116  to accurately position the cassette  74  in the up-and-down (Z) plane. 
   The latch  72  releasably retains the scroller cassette  42  in the installed position of FIG.  1 . The latch  72  is slideably retained on a top wall  122  of the cassette frame  48  by a fastener  124  extending through a slot  126  in wall  122 . The latch  72  is normally held in a centered position by a pair of springs  128  seated in spring cavities  130  in the underside of the latch  72  (FIG.  6 ). The springs  128  bear against tabs  132  ( FIG. 5 ) extending up from the wall  122 . A button  134  on the top of the latch  72  is used to slide the latch forward or rearward against a return force provided by one of the springs  128 . A rear latch nose  136  normally engages a mating latch opening  138  in the front plate  106  to retain the scroller cassette  42  in the installed position. The latch  72  also includes a forward latch nose  140  that normally extends forward to retain an accessory in the accessory mounting nest  64 . 
   Loading or removing the scroller cassette  42  is a quick and easy one-hand operation. The user holds the cassette in the hand and places it at the front portion  28  of the luminaire housing  24  so that the catches  108  enter the slots  110 . The cassette is moved down so that the pins  118  are received into the holes  120 . A chamfer  142  on the rear latch nose  136  causes the latch  72  to slide forward from its normal centered position as the nose  136  engages the front plate  106  or the housing cover  40 . As the cassette  42  reaches its installed position. the rear latch nose  136  is aligned with the latch opening  138  and the latch is returned forward by one of the springs  128 . The nose  136  enters the opening  130  the retain the cassette in place. 
   To remove the cassette, the user moves the button  134  forward to withdraw the rear latch nose  136  from the latch opening  138 . Then the cassette  42  is simply lifted from the luminaire housing  24  and moved forward, as pins  118  withdraw from holes  120  and slots  110  move free of catches  108 . To install or remove an accessory such as the light shield  66  from the accessory nest  64 , the user slides the button  134  rearward so that the forward latch nose  140  moves clear of the region between the flanges  62 . An accessory can then be moved vertically into or out of the nest  64 . 
   When the cassette  42  is installed on the luminaire housing  24 , the drive, fan and control board unit  44  is interconnected with the scroller cassette  42  by the interface coupling assembly  46 . The drive, fan and control board unit  44  includes a drive motor  144  that rotates a drive gear  146  (FIGS.  8  and  9 ). A drive belt  148  engages the drive gear  146  and a driven hub gear  150 . A toothed position wheel  152  and a cassette drive hub  154  at opposite sides of a support plate  155  are connected for simultaneous rotation with the driven hub gear  150 . 
   A control circuit  156  for components including at least the drive motor  144  is mounted at least in part on a control circuit board  158  attached by fasteners  160  to the base  113  (FIG.  7 ). A cable harness  162  ( FIG. 7 ) is connected to the control circuit board  158  of the drive, fan and control board unit  44  Position feedback information is provided by a position sensor  163  that senses the position wheel  152  and is mounted on a gel position circuit board  165 . As seen in  FIG. 8 , the control circuit board  158  is mounted in a cooing air flow channel  167  defined between the housing  112  and the base  113 . 
   A cooling fan  164  is mounted to the base  113 . The fan  164  includes a flow port array  166 , preferably an outlet flow port, directed down into the luminaire housing  24 . A second port array, preferably an inlet flow port, is defined in a louvered flow grate  168  opening at the upper surface of the housing  112 . 
   The flow port  168 , the cassette drive hub  154  and one of the drum drive pulleys  90 , together with a cooling air flow opening  170  in the cassette base wall  74  are components of the interface coupling assembly  46 . The opening  170  includes an opening  170 A in the base wall of the cassette frame  48  and an opening  170 B in the in the  4  bottom wall of the cassette cover  50  (FIG.  5 ). 
   The flow port  168  and the cassette drive hub  154  are located upon the housing  112  in positions to register with the gel scroller cassette  42  when the cassette is installed. In the installed position, the cassette drive hub  154  is coupled in a drive relationship to one of the drum drive pulleys  90 . In the preferred embodiment, a pair of hook and loop fastener pads  172  and  174  provide a releasable drive connection between the cassette drive hub  154  and the drum drive pulley  90 . 
   As can be seen in  FIG. 10 , a pulley shoulder plate  90 A defines a flat bottom pulley surface at the underside of the pulley  90 . An annular hook fastener pad  172  is adhered to the plate  90 A. A mating annular loop fastener pad  174  is adhered to the top surface of the cassette drive hub  154 . For example, the mating pads  173  and  176  may be self adhesive pads of VELCO (registered trademark of Velcro Industries) brand hook and loop material. When the cassette  42  is installed, the pad  172  engages the pad  174 , establishing a mechanical drive connection between the drive, fan and control board unit  44  and the gel scroller cassette  42  to rotate the gel drum assemblies  82  in response to rotation of the gel; drive motor  144 . The hook and loop fastener pads  172  and  176  provide a reliable, releasable connection with a long service life. There is no need to locate the pulley  90  and the drive hub  154  in any particular angular relationship in order to make the connection. There is no free play in the connection and it operates quietly. 
   A cooling air path is provided by the interface coupling assembly  46  between the interior of the gel scroller cassette and the interior of the luminaire housing  24 . In the installed position of the scroller cassette  42 , the cooling air flow opening  170  of the cassette  42  is aligned with the flow port  168  of the drive, fan and control board unit  44 . Part of the cooling air flowing through the fan  164  travels downward through the outlet flow port  166  and directly into the luminaire housing  24 . Another portion of the cooling air flow travels radially outwardly over a wall  176  ( FIG. 9 ) an through the cooling air flow channel  167  to cool components of the control circuit  156  mounted on the circuit board  158 . 
   The gel scroll  100  is a continuous elongated web of gel material having one or more varying characteristics, such as color or translucency, along its length. To change the effect of the scroll upon a light beam in the light passage  58  of the cassette  42 , the drums  84  are rotated to transfer the scroll  100  in selected alternate directions from drum to drum. As seen in  FIG. 11 , the cassette  42  includes a simple and self aligning scroll mounting system generally designated as  178 . Each of the two ends  180  of the scroll  100  has a tapered section  182  terminating in an elongated narrow end segment  184  having a securing hole  186  at its end. The hole  186  engages a recessed attachment post  188  of the corresponding drum  84 . This provides a mechanical connection permitting the scroll  100  to be wound upon the drum  84 . The scroll end can pivot about the post  188  and moves into the properly aligned position as the scroll is wound upon the drum. There is no need for adhesive tape or other separate fastening devices. the narrow portion  184  can be positioned in the light path to minimize the presence of the gel in the light beam. 
   When the gel scroller cassette is installed as seen in  FIG. 1 , as a result of the interface coupling assembly  46 , the drive motor  144  can be operated by the control circuit  156  to move the gel scroll  100  between the drums  84 . Rotation of the drive motor  144  rotates the drive gear  146  so that the drive belt  148  rotates the driven hub gear  150  and the cassette drive hub  154  together with the position wheel  152 . The cassette drive hub  154  is mechanically engaged with the corresponding drum drive pulley  90 , and the drive belt  98  engaging both pulleys  90  causes both drums  84  to rotate in a selected direction in order to position a desired segment of the gel scroll  100  in the light passage  58 . 
   A cooling air flow path is also established by the interface coupling assembly  46  when the cassette  42  is installed. The cooling air flow opening  170  of the cassette  42  registers with the flow port  168 . When the cooling fan  164  operates, air flows along a path including the interior of the cassette  42  behind the plane of the gel scroll  100 , through the opening  170  and into the flow port  168  of the fan  164 . The service life of the gel scroll is extended by the reduced heat resulting from the cooling air flow. In the preferred arrangement, cooling air is drawn into the cassette  42  from the exterior of the luminaire housing  24  and flows through the interior of the cassette, cooling the gel scroll  100 , and into the interior of the housing  24  where it provides cooling of other components including the control circuit  156  located in the channel  167 . 
   Because the drive, fan and control board unit  44  including the drive motor  144 , circuit board  158  and cooling fan  164  are mounted in the luminaire housing  24  and not within the gel scroller cassette  42 , the cassette  42  is relative light in weight and low in cost. An advantage of this arrangement is that the cassette can be installed and removed easily and quickly. Due to its low cost, it is practical to have a number of scroller cassettes  42  at hand for a luminaire  20  and, for example, to change color scrolls by replacing one cassette  42  with another rather than by changing the scroll in a single cassette  42 . Because neither the drive motor  144  nor the fan  164  is in the scroller cassette  42 , they can receive power and control signals provided within the luminaire  20  and it is not necessary to extend electrical connections or to connect electrical cables or conductors to the cassette  42 . 
   While the present invention has been described with reference to the details of the embodiments of the invention shown in the drawing, these details are not intended to limit the scope of the invention as claimed in the appended claims.