Abstract:
A color changing apparatus adapted to be installed between the reflector assembly and front barrel assembly of a theatrical ellipsoidal spotlight. The color changing apparatus includes a housing for connecting to the spotlight components. Contained within the housing are a plurality of color filters, preferably dichroic color filters, serially arranged perpendicular to the light path. The color filters may include constant or variable density patterns of any desirable color and are transported into the light path to effect a change in lighting conditions. The color changing apparatus is also preferably equipped with a control system enabling remote actuation and control of the system.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     The embodiments of the present invention generally relate to theatrical lighting systems that are digitally controlled and to the theatrical ellipsoidal spotlights used therein. More specifically, the embodiments of the present invention relate to color changing apparatus for theatrical ellipsoidal spotlights. 
     Lighting systems are typically formed by interconnecting, via a communications system, a plurality of lighting fixtures and providing for operator control of the plurality of lighting fixtures from a central controller. Such lighting systems may contain theatrical ellipsoidal spotlights. Applications and events in which theatrical ellipsoidal spotlights are used to great advantage include showrooms, television lighting, stage lighting, architectural lighting, live concerts, and theme parks. 
     Prior to the advent of relatively small commercial digital computers, remote control of light fixtures from a central controller was done with either a high voltage or low voltage current; see, e.g., U.S. Pat. No. 3,706,914, issued Dec. 19, 1972 to Van Buren, and U.S. Pat. No. 3,898,643, issued Aug. 5, 1975 to Ettlinger, both of which are incorporated by reference herein for all purposes. With the widespread use of computers, digital serial communication was widely adopted as a way to achieve remote control; see, e.g., U.S. Pat. No. 4,095,139, issued Jun. 13, 1978 to Symonds et al., and U.S. Pat. No. 4,697,227, issued Sept. 29, 1987 to Callahan, both of which are incorporated by reference herein for all purposes. In 1986, the United States Institute of Theatre Technology (“USITT”) developed a digital communications system protocol for theatrical lighting known as DMX. 
     A theatrical lighting system may include a central controller that uses the DMX protocol to communicate over a communication system to a plurality of dimming units. Each dimming unit may have a plurality of controlled outputs with each output being electrically connected to the lamp of an ellipsoidal spotlight. A single dimming unit may control the intensity of 4 or more of the ellipsoidal spotlights. For some shows, as many as 100 ellipsoidal spotlights connected to 25 dimming units may have their intensity individually controlled by an operator of the central controller. The operator of the central controller inputs address and command information that is sent over the communications system to individually control the intensity of each of the plurality of ellipsoidal spotlights. 
     For many theatrical shows, colored lighting is required to provide a dynamic effect on the stage. Most ellipsoidal spotlights have a mounting location for a color filter located in front of the final lens. The mounting location is commonly referred to as a gel holder. The term gel comes from the gelatin substrate sometimes used to manufacture color filters. Gels today may be constructed of polycarbonate flexible sheeting to help resist the high temperatures associated with the light energy projected from the ellipsoidal spotlight. A sheet of colored gel may be held in a frame, which may be located or fixed relative to the gel holder of the ellipsoidal spotlight. Even though the gels may be constructed of polycarbonate, the light energy from the colors not transmitted by the gels is absorbed by the gels, thus elevating the temperature of the gel. Therefore, the gels must be changed frequently by show maintenance personnel because the gel color fades or the sheeting distorts due to the high heat absorbed by the gel. The labor costs to change the gels frequently for large shows can be quite high. 
     Color scrolling devices have been manufactured in order to allow remote controlled selection of a desired gel color for a particular spotlight by an operator of the central controller. The color scroller device often includes one or more scrolling rolls of gel sheeting, where each of the rolls of gel can be remotely controlled to scroll through the length of gel sheeting. One exemplary gel scrolling system using multiple scrolls or variable saturation is disclosed in U.S. Pat. No. 5,126,886 to Richardson, et al and is incorporated by reference herein for all purposes. 
     The gel scrolling system disclosed by Richardson is an improvement over the prior art color changing gel scrollers because it uses multiple gel scrolls each of a different color and each with variable saturation. Thus, the operator of the central controller may gradually change a first color to a second color by varying the saturation of the multiple gel scrolls in front of the ellipsoidal spotlight. The gel used in the Richardson gel scroller still has the disadvantage of fading and distorting over time and maintenance is again required to apply new gel material to the scrolls. 
     One popular theatrical ellipsoidal spotlight model is the Source Four™ as manufactured by Electronic Theatre Controls of Middleton, Wis. The Source Four™ ellipsoidal spotlight has a modular construction so that various lens systems can easily be applied to suit the application of a particular show. The Source Four™ ellipsoidal spotlight is constructed of a reflector housing assembly and front barrel assembly that may include a lens tube assembly. These assemblies are easily disassembled and reassembled in that the reflector assembly can be disconnected from the front barrel assembly and the lens tube assembly can be removed from the front barrel assembly. 
     Therefore, it is possible to produce a modular, housing-based optical system that can be designed to mate with the reflector assembly and the front barrel assembly of the Source Four™ spotlight. At least one company has built a modular optical apparatus that mates the reflector assembly with the front barrel assembly of an ellipsoidal spotlight. The Great American Market Company of Hollywood, Calif. has produced a product called an SX4© that may be used to automatically change or scroll patterns in the light path and is installed between the reflector assembly and the front barrel assembly of a Source Four™ ellipsoidal spotlight. 
     There is need for an improved color changing apparatus to be used in conjunction with a conventional theatrical ellipsoidal spotlight and that does not possess the drawback of incorporating gel color filters that fade or distort and yet can produce a broad range of varying color. 
     SUMMARY OF THE PREFERRED EMBODIMENTS 
     The embodiments of the present invention include a color changing apparatus adapted to be installed between the reflector assembly and front barrel assembly of a theatrical ellipsoidal spotlight. The color changing apparatus includes a housing for connecting to the spotlight components. Contained within the housing are a plurality of color filters, preferably dichroic color filters, serially arranged perpendicular to the light path. The color filters may include constant or variable density patterns of any desirable color and are transported into the light path to effect a change in lighting conditions. The color changing apparatus is also preferably equipped with a control system enabling remote actuation and control of the system. 
     One embodiment includes a color changing apparatus for a theatrical ellipsoidal spotlight having a reflector housing and a front barrel housing. The color changing apparatus has a housing with first and second sides, a first fastening system, for releasably joining the first side of the housing to the reflector housing, and a second fastening system, for releasably joining the second side of the housing to the front barrel housing. A plurality of color filters, preferably dichroic color filters, is contained at least in part within the housing. In certain embodiments, the color filters are serially arranged, include filters that are cyan, magenta, and yellow, and may be transported by an actuator to be into or out of a light path that is created by the reflector of the ellipsoidal spotlight. 
     In another embodiment, the color changing apparatus for a theatrical ellipsoidal spotlight includes a housing joining a reflector housing and a front barrel housing of the theatrical ellipsoidal spotlight. Light is projected along a path from the reflector, through said housing and through the front barrel. A plurality of dichroic color filters are disposed within the housing and at least one of said plurality of dichroic filters has a variable density pattern. The apparatus also has a control system including a plurality of actuators and a communications port, wherein the control system is adapted to adjust the position of the plurality of dichroic filters. The communications port receives a command and the control system acts on the command to control the actuators so as to transport selected dichroic filters into the light path. The communications port may be connected to at least one external connector adapted to relay both power and communications. 
     In another alternative embodiment, a theatrical lighting system includes two theatrical ellipsoidal spotlights, each containing a pattern gate, a color changing apparatus, a reflector housing, and a front barrel housing. The color changing apparatus are conjoined with reflector housings and the front barrel housings of the ellipsoidal spotlights. The color changing apparatus comprise a plurality of dichroic filters serially arranged between the reflector housing and the front barrel housing. Each color changing apparatus includes a control system connected to the first color changing apparatus by a communications port adapted to receive a command signal to cause the plurality of dichroic filters to be transported into a light path created by the reflector housing of the theatrical spotlight. 
     Another embodiment includes a method for projecting light on a surface by providing a plurality of color filters disposed within a housing, installing the housing in a theatrical ellipsoidal spotlight comprising a pattern gate, between a reflector housing and a front barrel housing, to form a light path that runs from the reflector, through the housing, and into the front barrel, and projecting light from the reflector along the light path and onto the surface. 
     An alternative embodiment includes a method for controlling light projected onto a surface by providing a plurality of color filters disposed within a housing that is installed between a reflector housing and a front barrel housing of a theatrical ellipsoidal spotlight establishing a light path that runs from the reflector, through the housing, and into the front barrel, connecting a plurality of actuators to the plurality of color filters, wherein the plurality of actuators are adapted to transport each of said plurality of color filters into and out of the light path, and transmitting a command to the control system causing one of the plurality of actuators to transport one of the plurality of color filters into the light path. 
     Thus, the present invention comprises a combination of features and advantages that enable it to overcome various problems of prior art theatrical ellipsoidal spotlights. The various characteristics described above, as well as other features, objects, and advantages, will be readily apparent to those skilled in the art upon reading the following detailed description of the preferred embodiments of the invention, and by referring to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more detailed understanding of the preferred embodiments, reference is made to the accompanying Figures, wherein: 
     FIGS. 1A-1C are schematic representations of a prior art theatrical ellipsoidal spotlight; 
     FIG. 1D is a schematic representation of the spotlight of FIGS. 1A-1C equipped with a prior art color changing apparatus; 
     FIG. 2 is a schematic representation of one embodiment of a color changing apparatus constructed in accordance with the present invention conjoined with the ellipsoidal spotlight components of FIGS. 1A-1C; 
     FIG. 3A is a front external schematic view of the color changing apparatus of FIG. 2; 
     FIG. 3B is a side external schematic view of the color changing apparatus of FIG. 2; 
     FIG. 3C is a rear external schematic view of the color changing apparatus of FIG. 2; 
     FIG. 4A is an internal schematic view of the color changing apparatus of FIG. 2, shown in a first state; 
     FIG. 4B is an internal schematic view of the color changing apparatus of FIG. 2, shown in a second state; 
     FIG. 5 is a front internal schematic view of the color changing apparatus of FIG. 2; 
     FIG. 6 is a block diagram of one embodiment of an electrical system for operating a color changing apparatus; and 
     FIG. 7 is a schematic view of a theatrical lighting system incorporating two color changing apparatus. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the description that follows, like parts are marked throughout the specification and drawings with the same reference numerals, respectively. The drawing figures are not necessarily to scale. Certain features of the invention may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in the interest of clarity and conciseness. The present invention is susceptible to embodiments of different forms. There are shown in the drawings, and herein will be described in detail, specific embodiments of the present invention with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to that illustrated and described herein. It is to be fully recognized that the different teachings of the embodiments discussed below may be employed separately or in any suitable combination to produce the desired results. 
     FIGS. 1A-1C show the construction of a prior art theatrical ellipsoidal spotlight  10 . Referring first to FIG. 1C, The ellipsoidal spotlight  10  is comprised of two separate housings shown as the reflector assembly housing  50  and the front barrel assembly housing  70 . The reflector assembly housing  50  will be referred to herein as the reflector housing for simplification. The front barrel assembly housing  70  will be referred to herein as the front barrel housing for simplification. 
     Referring now to FIG. 1A, the reflector housing  50  is comprised of the housing  15 , the reflector  18 , the lamp  16 , and mating flanges  20   a  and  20   b . The lamp  16  may also be contained in part within a lamp assembly that is fixed to the reflector housing but not shown for simplification. Referring now to FIG. 1B, the front barrel housing  70  is comprised of the housing  25 , the mating flanges  28   a  and  28   b , and the pattern gate  26 . The lens barrel assembly  40  may also be installed as part of the front barrel housing  70 . The lens barrel assembly  40  consists of input lens  42 , output lens  44 , and a gel frame holder flanges  46   a  and  46   b . As shown in FIG. 1C, the ellipsoidal spotlight  10  shows that the flanges  20   a  and  20   b  of the reflector housing  50  are conjoined with flanges  28   a  and  28   b  of the front barrel housing  70  to form the assembled prior art ellipsoidal spotlight  10 . 
     FIG. 1D shows ellipsoidal spotlight  10  including a scrolling color changing apparatus  101  of the prior art. Apparatus  101  is shown as a gel scroller fixed to the gel frame holder flanges  46   a  and  46   b  that are attached to the lens barrel assembly  40 . The gel scroller  101  is comprised of a housing  110 , a gel feed roller  106 , a linear roll of gel material  108  that is positioned, in part, across the output lens  44 , and a take up roller  104 . The gel scroller  101  also comprises the mating flanges  102   a  and  102   b  that are shown conjoined with gel frame holder flanges  46   a  and  46   b  so that the gel scroller  101  is fixed to the theatrical ellipsoidal spotlight  10 . 
     In operation, electrical power is applied to the lamp  16  and the lamp emits white light. The white light from the lamp  16  is collected by the reflector  18  and directed along a path towards the input lens  42  in the direction of arrow  206 . The white light is collected by input lens  42  and directed to output lens  44  where it is directed through the colored gel material  108 , thus producing colored light that is projected upon a stage (not shown). The pattern gate  26  is shown without a pattern installed for simplification but it is known within the prior art to insert stenciled images or slides into the pattern gate  26 . These slides are inserted from the exterior of the front barrel housing  70  and focused upon by the input lens  42  to be projected by the output lens  44  as an image onto the stage (not shown). The gel scroller  101  is electrically powered to cause the take-up roller  104  to take up the linear gel roll of material  108  from the feed roller  106  by a mechanical system of actuator motors (not shown). The linear gel material  108  may be comprised of different colored sections of gel or different saturations of color throughout the linear roll. The action of the rollers  104  and  106  may be remotely controlled from a central controller, as known in the prior art. 
     FIG. 2 shows one embodiment of a color changing apparatus  200  joined to the reflector housing  50  and the front barrel housing  70  from FIGS. 1A-1C to produce an improved ellipsoidal spotlight  250 . The components shown as  15 ,  16 ,  18 ,  22   a  and  22   b  comprising the reflector housing  50  are the same as those shown comprising the reflector housing  50  of FIG.  1 A. The components shown as  25 ,  28   a ,  28   b ,  26 ,  40 ,  42 ,  44 ,  46   a  and  46   b  of the front barrel housing  70  are the same as those shown comprising the front barrel housing  70  of FIG.  1 B. 
     The color changing apparatus  200  is comprised of a serially arranged plurality of color filters  202   c ,  204   c ,  202   m ,  204   m ,  202   y  and  204   y . The color filters  202   c ,  204   c ,  202   m ,  204   m ,  202   y  and  204   y  are preferably rectangular dichroic color filters. Dichroic color filters do not fade or distort like the gel filters used in conventional color scrollers. By way of example, the color filters  202   c  and  204   c  are a pair of cyan color filters, the color filters  202   m  and  204   m  are a pair of magenta color filters, and the color filters  202   y  and  204   y  are a pair of yellow color filters. The color filters  202   c ,  204   c ,  202   m ,  204   m ,  202   y  and  204   y  may preferably have a variable density pattern applied that allows for variable saturation of color as the color filters are translated to intercept the light path  206  that is created by the light from the lamp  16  cooperating with the reflector  18 . 
     The color changing apparatus  200  also comprises a housing  201  in which the color filters  202   c ,  204   c ,  202   m ,  204   m ,  202   y  and  204   y  are located. Housing  201  has a set of input mating flanges  220   a  and  220   b  that are disposed around the light input aperture  208 , the extremities of which are indicated by points  208   a  and  208   b . The input mating flanges  220   a  and  220   b  of the color changing apparatus  200 , are designed to mate with the mating flanges  22   a  and  22   b  of the reflector housing  50 . When the input mating flanges  220   a  and  220   b  are mated with mating flanges  22   a  and  22   b  of the reflector housing  50 , the color changing apparatus  200  is conjoined with the reflector housing  50 . While only two input mating flanges are shown fixed to the housing  201  of the color changing apparatus  200 , more than two mating flanges may be used. 
     A set of output mating flanges  228   a  and  228   b  are shown fixed to housing  201  of the color changing apparatus  200  of FIG.  2 . The output mating flanges  228   a  and  228   b  are designed to mate with the mating flanges  28   a  and  28   b  of the housing  25  of the front barrel housing  70 . When the input mating flanges  228   a  and  228   b  are mated with mating flanges  28   a  and  28   b  of the front barrel housing  70 , the color changing apparatus  200  is conjoined with the front barrel housing  70 . While only two input mating flanges are shown fixed to the housing  201  of the color changing apparatus  200 , more than two mating flanges may be used. Although mating flanges are shown for conjoining the reflector housing  50  to the color changing apparatus  200  and conjoining the color changing apparatus  200  to the front barrel housing  70 , other types of fastening systems may be used. 
     The light generated by the reflector housing  50  along the light path  206  passes through the light input aperture  208  of the color changing apparatus  200  and passes without intersecting the color filters  202   c ,  204   c ,  202   m ,  204   m ,  202   y  and  204   y . Next, the light passes through the light output aperture  210  that has its extremities indicated by  210   a  and  210   b . The light exiting the output aperture  201  is gathered by the input lens  42  and next heads in the direction of output lens  44  where it is projected upon the stage (not shown). 
     FIG. 3A shows a front external view of the color changing apparatus  200  of FIG.  2 . The light input aperture  208  as indicated by the extremities  208   a  and  208   b  is shown. The light input aperture  208  is preferably a round aperture. Two input mating flanges  220   a  and  220   b  are shown. A power and communications input and output connectors are shown as  311  and  312  respectively. A digital display  324  and an input switch array  325  are shown. The digital display  324  and the input switch array  325  can be used to set an operating address for the color changing apparatus  200 . 
     FIG. 3B shows a side external view of the color changing apparatus  200  of FIG.  2 . The input mating flanges  220   a  and  220   b  fixed to the housing  201  are the same as those shown in FIG.  2 . The output mating flanges  228   a  and  228   b  fixed to the housing  201  are the same shown in FIG.  2 . 
     FIG. 3C shows a rear external view of the color changing apparatus  200  of FIG.  2 . The light output aperture  210  as indicated by the extremities  210   a  and  210   b  is shown. The light output aperture  210  is preferably a round aperture. Two output mating flanges  228   a  and  228   b  are shown and are the same as those shown in FIG.  2 . 
     FIG. 4A shows a more detailed side view of the color changing apparatus  200  of FIG. 2 in a first state. Components  202   c ,  204   c ,  202   m ,  204   m ,  202   y ,  204   y ,  220   a ,  220   b ,  208 ,  208   a ,  208   b ,  228   a ,  228   b ,  210 ,  210   a ,  210   b  and  201  are the same shown in FIG.  2 . An electronic control system  301  is shown. Components  311 ,  312 ,  324  and  325  are the same as those shown in FIG.  3 A. Three motor actuators  362 ,  364  and  366  are shown. The motor actuator  362  is arranged to transport the cyan color filter pair  202   c  and  204   c  gradually into and out of the light path as shown by arrow  206   a  that passes through the input aperture  208  to the output aperture  210 . The motor actuator  364  is arranged to transport the magenta color filter pair  202   m  and  204   m  gradually into and out of the light path that passes through the input aperture  208  to the output aperture  210 . The motor actuator  366  is arranged to transport the yellow color filter pair  202   y  and  204   y  gradually into and out of the light path that passes through the input aperture  208  to the output aperture  210 . The motor actuators  362 ,  364  and  366  are arranged to transport their pairs of color filters gradually into and out of the light by any suitable mechanical means such as belts or gears. The motors actuators may be DC servo motors, stepper motors or other electronic actuators. It is preferred that the actuators are stepper motors. 
     FIG. 4B shows a more detailed side view of the color changing apparatus  200  of FIG. 2 in a second state. Components  202   c ,  204   c ,  202   m ,  204   m ,  202   y ,  204   y ,  220   a ,  220   b ,  208 ,  208   a ,  208   b ,  228   a ,  228   b ,  210 ,  210   a ,  210   b  and  201  are the same shown in FIG.  2 . An electronic control system  301  is shown. Components  311 ,  312 ,  324  and  325  are the same as those shown in FIG.  3 A. Three motor actuators  362 ,  364  and  366  are shown. FIG. 4B shows that the motor actuator  362  has transported the cyan color filter pair  202   c  and  202   y  into the light path. The light path is shown by arrow  206   a.    
     FIG. 5 shows a more detailed front view of the color changing apparatus  200  of FIG. 2 in a first state. Components  202   c ,  204   c ,  210  and  201  are the same as those shown in FIG.  2 . An electronic control system  301  is shown. Components  311 ,  312 ,  324  and  325  are the same as those shown in FIG.  3 A. Three motor actuators  362 ,  364  and  366  are shown. The color filters  202   c  and  204   c  are shown with a variable density color pattern  505  applied to both filters  202   c  and  204   c . The color pattern  505  is applied to the other color filters  202   m ,  204   m ,  202   y  and  204   y  (not shown in FIG. 5 for simplification) that comprise the color changing apparatus  200 . The variable density color pattern  505  may be any color pattern applied to the color filters  202   c ,  204   c ,  202   m ,  204   m ,  202   y  and  204   y  that allows for variable saturation of the light path as the color filters are gradually inserted into the light path. The variable density color pattern  505  may be applied to the color filters by silk screen, laser ablation or chemical etching. The creation of variable density color patterns is known in the prior art. The color pattern  505  may be the same pattern applied to the color filters  202   c ,  204   c ,  202   m ,  204   m ,  202   y , and  204   y  or the pattern may be different for each color in order to optimize how much of the color is applied to the light path by the actuators  362 ,  362  or  366 . 
     FIG. 6 shows the color changing apparatus of FIG. 2 but with detail applied to the electronic control system  301 . The housing  201  houses the electronic control system  301  and the motor actuators  362 ,  364  and  366 . Components  311 ,  312 ,  324  and  325  are the same as those shown in FIG.  3 A. Power and communications input and output connectors shown as  311  and  312  may connect to a power and communications interface shown as  728  in FIG.  7 . The power and input connectors  311  and  312  may be connected in parallel and either may be used as an input or output power and communications connector. The power and input connectors  311  and  312  when connected to the power and communications interface  728  of FIG. 7 can supply power and communications to the communications port  611 . Power for the motor actuators  362 ,  362  and  366  as well as the processor  616 , the memory  615  and the motor control interface  618  may also be provided from the power and communications interface  728  of FIG.  7  through the power and communications input and output connectors  311  and  312 . 
     The communications port  611  may be a part of the processor  616 . The memory  615  may also be a part of the processor  616 . For example, an integrated processor that contains the communications port  611  and the memory  615  may be used as a component of the electronic control system  301 . The memory  615  may contain an operating address that can be entered by a theatrical technician by using the input switch array  325 . Alternatively, the operating address can be stored as a value setting of the input switch array itself. In either case, the color changing apparatus  200  should have an operating address that is unique so that a plurality of color changing apparatus similar to  200  can receive commands separately and each color changing apparatus can act on commands that are unique to a particular color changing apparatus. 
     FIG. 7 shows a theatrical lighting system  700  incorporating the color changing apparatus  200 . Improved theatrical spotlight  250  is the same as theatrical spotlight  250  of FIG.  2  and has the color changing apparatus  200  conjoined with the reflector housing  50  and the front barrel housing  70 . Improved theatrical spotlight  750  of FIG. 7 has the color changing apparatus  740  conjoined with the reflector housing  50  and the front barrel housing  70 . The color changing apparatus  740  is the same as color changing apparatus  200 . The improved theatrical ellipsoidal spotlights  250  and  750  have a pattern gate  26  that is the same as the pattern gate  26  of FIG.  1 . The pattern gate allows a theatrical lighting designer to install stenciled images or slides into the pattern gate  26  from the exterior of the front barrel housing to be focused upon by the input lens  42  and then projected by the output lens  44  as an image onto the stage. 
     Theatrical spotlight  250  of FIG. 7 has the lamp  16  contained at least in part of the reflector housing  50  connected to a dimmer cable  722  so that power to the lamp can be controlled. Theatrical spotlight  750  has its lamp contained within the lamp housing  50  and connected to an additional dimmer cable  724  so that power to the lamp can be controlled. The dimmer cables  722  and  724  supply variable power to the lamps located in the reflector housing  50  of theatrical spotlights  250  and  750  from a theatrical dimmer pack  720 . Theatrical dimmer packs are known in the prior art for supplying variable power to the lamps of theatrical ellipsoidal spotlights based upon commands received by the theatrical dimmer pack  720  over a communications system from a central controller such as central controller  150 . 
     Commands and address signals are sent from the central controller  150  to the theatrical dimmer pack  720  over communications cable  718 . The command and address signals from the central controller  150  are then passed on by the theatrical dimmer pack  720  to the power and communications interface  728  by communications cable  726 . The power and communications interface  728  receives address and command signals from the central controller  150  over cable  726 . The power and communications interface  728  may process the command and address signals and sends power, command and address signals to the color changing apparatus  200  and  740  over power and communications cables  730 . The power and communications cable  730  is connected to connector  312  of the color changing apparatus  200 . 
     A power and communications cable  732  is connected to connector  312  of color changing apparatus  200  and is routed to connector  311  color changing apparatus  740  so that power and communication can be received. The power and communications interface  728  is connected to an exterior source of power not shown. The central controller  150  may contain a visual display  152  that may be a video monitor, a keyboard entry system  154  and input devices  156 . 
     During operation of the theatrical lighting system  700 , an operator of the central controller  150  may wish to adjust the color of light projected by a particular ellipsoidal spotlight. The operator may first enter the operating address of the color changing apparatus of the particular ellipsoidal the operator wishes to control. If the operator wishes to control the color of the light projected by the ellipsoidal spotlight  250 , the operator first enters the operating address of the color changing apparatus  200  by inputting the appropriate operating address into the keyboard entry system  154 . The operating address of the color changing apparatus  200  associated with ellipsoidal spotlight  250  is received by the power and communications interface  728  and is routed to the color changing apparatus  200 . The color changing apparatus  200  receives the operating address at the communications port  611 . The communications port  611  of FIG. 6 passes the received operating address to the processor  616  where it is compared to the stored operating address. 
     If the received operating address and the stored operating address match, then the color changing apparatus  200  is ready to act on a command sent from the central controller  150 . Next, the operator sends a color changing command from the central controller  150  to the color changing apparatus  200 . The color changing command is received by the communications port  611  of FIG.  6  and acted upon by the processor  616  in accordance with operational code stored in the memory  615 . The processor  616  acting in accordance with the memory  615  sends control signals to the motor control interface  618  to control the motor actuators  362 ,  364  or  366  to incrementally transport the color filters  202   c ,  204   c ,  202   m ,  204   m ,  202   y  and  204   y  into the light path. 
     A color changing command for the cyan color may cause the cyan color filters  202   c  and  204   c  to be transported by the motor actuator  362  to intersect the light path at a point where the light path is 50 percent saturated with cyan color. Another example of a color changing command might affect the magenta color filters  202   m  and  204   m  to be transported by the motor actuator  364  into the light path at a point where the light path is 100% saturated with magenta color. Various color changing command values allow the operator of the central controller  150  to vary the saturation of the cyan, magenta and yellow colors of the light projected incrementally upon the stage by the ellipsoidal spotlight  250 . 
     The operator of the central controller  150  may next wish to adjust the color of the improved ellipsoidal spotlight  750 . By entering the proper operating address of the color changing apparatus  740  into the central controller  150 , the operator may next send color changing commands to the color changing apparatus  740  to incrementally vary the saturation of the cyan, magenta, and yellow colors of the light projected by the ellipsoidal spotlight  750 . A single command may be sent from the central controller  150  to be received by the communications port  611  of FIG. 6 of color changing apparatus  740  that causes the transport of all color filters out of the light path and insures that white light is projected upon the stage (not shown). 
     An improved color changing apparatus has been disclosed that conjoins with a lamp housing of a theatrical ellipsoidal spotlight. The improved color changing apparatus also conjoins with a front barrel housing of a theatrical ellipsoidal spotlight. The improved color changing apparatus can easily be retrofitted to theatrical ellipsoidal already used in theatre shows. The improved color changing apparatus allows remote controlled varying of the color of light projected by the ellipsoidal spotlight. Dichroic filters are used instead of gels so that the color filters do not fade or distort. 
     While a preferred embodiment of the invention has been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit or teaching of this invention. The embodiments described herein are exemplary only and are not limiting. Many variations and modifications of the system and apparatus are possible and are within the scope of the invention. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims.